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IINDING  LIST  FEB  1  5  1923 


El 


{THE 

Electric  Journal 


VOL.  XVIII 

JANUARY-DECEMBER 

1921 


Copyright,  1922  by  The  Electric  Journal 


Publication  Office 

TWELFTH  FLOOR,  KEENAN  BUILDING 
PITTSBURGH.  PA. 


THE  ELECTRIC  JOURNAL 

PITTSBURGH,  PA. 


B.  G.  Lam  ME 


Publication  Committee 
A.  H.  McIntire 


Chas.  Robbins 


A.  H.  McIntire 
Editor  &  Matiager 


Chas.  R.  Riker 
Technical  Editor 


M.  M.  Bries 
Assist.  Editor 


Chas.  F.  Scott 
B.  A.  Beiirend 


Associate  Editors 
E.  H.  S.xiFFiN  H.  P.  D.wis 

F.  D.  Newbury 


N.  W.  Storer 
C.  E.  Skinxer 


TABLE  OF  CONTENTS 
1921 


JANUARY 

Public      Utility      Economics — G.      E. 

Tnijp     ; 

A  Perspective  View — E.  H.  Sniffin.... 
The    Problem    of    the    Electric    Rail- 
ways— M.   B.  Lambert 

Present  Trend  of   Electrical  Develop- 
ment— J.    J.    Gibson 

The     Electrification     of     Industry — J. 

M.    Curtin    

Enameling  in  the  Automobile  Industry — 

M.   R.    Armstrong 

The  Electrical  Characteristics  of  Trans- 
mission  Conductors  with   Steel    Cores — 

H.    B.    Dwight 

Efficiency    of    Adjustable    Speed   Motors— 

R.   W.  Owens - U  C 

Phase  Transformation  with  Autotrans- 
formers  —  ThreoPhase     to     Two-Phase 

Three-Wire— E.  P.   Wimmer 

Application    of     Steam     Condensers — II — 

Selection  of  Size — F.  A.   Burg 

Power-Factor    in    Polyphase    Circuits — A. 

Nyman    

Three-Phase  Current  Limiting  Reactors — 

M.   E.    Skinner -... 

Mechanical  Construction  of  Water  Wheel 

Driven   Alternators — E.  Mattman 

Typical  Relay  Connections — L.  A.  Terven 
Voltage   Relations  in   Direct-Current  Ma- 
chines—R.    E.    Ferris 

The  Liquid  Slip  Regulator— Guy  F.  Scott 

Snow  Fighting  Methods  on  the  Electrified 

Section    of    the    Chicago,    Milwaukee    & 

St.    Paul   Railroad— E.    Sears 

Reminiscences  of  the   Erie  Electrification 

at  Rochester — W.   Nelson  Smith 

Question    Box.    Nos.    1946-1961 - 

Railway  Operating  Data — Types  of  Tran- 
sition Used  to  Obtain  Series-Parallel 
Operation — H.  R.  Meyer 


Typical  Relay  Connections — II. — Lewis  A. 

Terven     

A    New    Form    of    Standard    Cell— C.    J. 

Rodman  and  T.   Spooner 

High-Speed   Circuit   Breakers — Air   Brake 

Type — G.  G.  Grissingcr 

Portable  Electrical  Equipment  for  Motion 

Picture   Photography — J.   A.   White. 

Question    Box,    Nos.    1962-1974 

Railway    Operating    Data — The   Handling 

of  Copper — J.  V.  Dobson 


FEBRUARY 

Regulation   by   Synchronous   Convert- 
ers— F.    D.    Newbury 

Railway    Utilities    Approaching    Sta- 
bility -A.  H.  McIntire 

The     Dual     Drive     Units — Ivan     Stewart 

Forde     

Commutator     Brushes     for     Synchronous 

Converters — R.   H.    Newton 

Voltage     Regulating     Systems     of     Syn- 
chronous   Converters — F.   T.   Hague 

Adjustable     Laboratory     Rheostats — Thos. 

Spooner    _ 

A  Vector  Diagram  for  Salient-Pole  Alter- 
nators— E.   B.    Shand 


MARCH 

Electrical   Paper  Machine   Drive — W. 

H.  Artz  77 

)  Automatic  Speed  Control  for  Sectional 
Paper  Machine  Drive — Stephen  A. 
Staege  78 

Automatic  Electric  Enameling  Oven  In- 
stalled at  Forderer  Cornice  Works, 
San    Francisco— Elbert   Kramer 82 

Renewal  of  the  Catenary  Construction  in 
the   Hoosac   Tunnel— L.    C.    Winship 84 

Principles  and  Characteristics  of  Syn- 
chronous Motors— E.   B.  Shand _ 87 

Experience  in  Drying  Out  Large  Trans- 
formers—S.  H.  Abbott 92 

The  Development  of  Magnetic  Materials 
— T.  D.  Yensen _ 93 

Arc  Welding  Equipment  in  the  Foundry — 
W.   W.   Reddle 96 

Typical  Relay  Connections — lU — Lewis 
A.   Terven   99 

Some  Labor  Conditions  in  Foreign  Coun- 
tries—W.   G.  McConnon 102 

Operating  Data  —  Commutator  Mainte- 
nance of  Synchronous  Converters — R. 
H.   Newton    _ 105 

Question  Box,  Nos.  1975-1981 106 

Railway  Operating  Data  —  Armature 
Record   Tags — John   S.   Dean „ 108 

APRIL 

Radio — Its  Future — H.  P.  Davis 109 

Radio — Its  Relation  to  the  Electrical 

Industry— W.  S.  Rugg 109 

An    Early    High    Frequency    Alterna- 
tor— B.    G.    Lamme .«. 110 

Epoch   Making   Radio    Inventions   of  Fes- 

senden — S.   M.   Kintner Ill 

The    Lafayette   Radio    Station— Comm.    S. 

C.  Hooper,  U.  S.  N 112 

Descriiition  of  a  Uni-Wave  Signaling 
System     for     Arc     Transmitters — Lieut. 

W.  A.  Eaton.  U.  S.  N 114 

The  Heterodyne  Receiver — John  V.  L. 
Hogan     _ 116 


The  Foundations  of  Modern  Radio— L.  W. 

Chubb  and  C.  T.  Allcutt , 120 

Static  Frequency  Doublcrs — J.  F.  Peters..     122 
Continuous  Wave  Radio  Communication — 

D.    G.    Little — 124 

Why  High   Frequency  for  Radiation? — J. 

Slepian 129 

Data  and  Tests  on  10,000  Cycle  per  Sec- 
ond  Alternator — B.   G.   Lamme 182 

Continuous  Wave  Radio  Receivers — M.  C. 

Batsel    1S6 

Radio   Arc   Transmitters— Q.   A.    Brackctt     142 
Remote  Control  by  Radio — A.  L.  Wilson..     146 
Education  of  Radio  Engineers — Communi- 
cation    Engineering    at     Yale — H.     M. 

Turner    _ 149 

Westinghouse    Technical    Night    School — 

W.   W.   Reddie 150 

The      Regenerative      Circuit — Edwin      H. 

Armstrong  - 163 

Question    Box,  Nos.    1982-1985 _ 156 

Railway    Operating   Data — First    Aid   for 
Electrical    Injury — John    S.    Dean 156 


MAY 

The  National  Electric  Light  Associa- 
tion— Martin  J.  Insull _ 167 

Constructive    Suggestions    by   a   Past 

President— R.  H.  Ballard...r. 168 

The     Utilities'     Situation— Milan     R. 

Bump    - 169 

'The  Manufacturer  and  the  N.   E.   L. 

A.— Frank  W.  Smith 160 

The  Technical  Work  of  the  National 
Electric    Light    Association — I.    E. 

Moultrop    161 

Some   Thoughts    in    Connection    with 
the   Sale   of   Stock    to   Customers — 

John    F.   Gilchrist 161 

Conserving   Capital    and   Natural   Re- 
sources—Edwin D.  Dreyfus 163 

The    Use    of    Central    Station    Power 

by   Industrial    Plants — Brent   Wiley     164 
The    Pittsburgh    Power    Zone — A.    H. 

McIntire  . ..- 165 

An   80  Mile  Central   Station   Bus — C. 

S.    Cook   166 

The    Central    Station    Company    as    a 

Community   Asset— A.   M.   LoTin 167 

Now    for    the    N.    E.    L.    A.    Conven- 
tion—E.  H.  Sniffin 168 

The  Transmission  System  of  the  West 
Penn  Power  Company — Geo.  S.  Hum- 
phrey      169 

The  Generating  System  of  the  West  Penn 

Power  Company— G.  G.  Bell 175 

The  Industrial  Field  of  the  West  Penn 
Power  Company — G.   H.   Gadsby 189 


The     Power     Stations    of     the    Duquesne 

Light   Company-J.   M.   Graves^. 193 

The  Transmission   Ring  of   the  Duquesne 

Light  Company— E.  C.  Stone.^. -i" 

Power    Requirements    in    the    Pittsburgh 

District— Joseph  McKinley  .        .......^...-...     ■!" 

The    Power    System    of    the    U.    S.    bteel 

Corporation  in  Pittsburgh-S.  S.  Wales  222 
Water    Power    Developments — Daniel    W. 

Mead   - ; •;     ''-' 

The    70.800    Kv-a    Transformer    Bank    ot 

the    Colfax    Generating    Station    of    the 

Duquesne      Light      Company  —  M.      B.     ^^^ 

Heat    Balance    Systems— F.    C.   Chambers 
and  J.  M.  Drabelle ''*>•» 


JUNE 

Electrical   Propulsion   for   Battleships 

—Wilfred    Sykes   ■...; •;•■•.• ■>' 

The   Battleship  is  a  Fighting   Ship— 

W     S     RucE  ""*     ^'*" 

Electric   Drive  and"  the  U."  S.   S.  Tennes- 

see— H.   M.   Southgate ■-•■.•     ^'^ 

Motion— $30,000,000      Worth— Commander 

R.  A.  Bachman.  M.  C.  U.  S.  N. — ...     't'^ 

General  Arrangement  of  Propelling  Ma- 
chinery   of    the    U.    S.    S.    Tennessee- 

W.    E.    Thau....^._.. .-......-........■..„••     ^45 

The    Propelling    Motors   of    the   U.    b.    b. 

Tennessee — H.    L.    Barnholdt ^ ^=>'^ 

The  Control  Room  Circuit  Breaker  Equip- 
ment of  the  U.  S.  S.  Tennessee-E.  K.     ^^^ 

The  ControfEquipment  for  the  Propell- 
ing Machinery  of  the  U.  S.  S.  Ten- 
nessee--M.    Cornelius    ;.-■■■. '=•'•' 

Lighting  Sets  on  the  U.  S.   S.  Tennessee 
—J.     A.     MacMurchy     and     Albert     O.     ^^^ 
Loomis    ;"■■;;■.', ■'7,""'"v'"« 

Condensing  Equipment  and  Oil  Cooling 
System  for  the  U.  S.  S.  Tennessee— 
John  H.  Smith  and  Albert  O.  Loomis....     iii 

The  Control  of  the  Secondaries  of  the 
Main  Propulsion  Motors  of  the  U.  i). 
S.    Tennessee-W.    C.    Goodwin. 278 

The  Stability  Indicator— R.  T.  Pierce  280 

Main   Turbines   and   Turbine   Speed    Con- 
trol for  the  U.  S.  S.  Tennessee-W.  B.     ^^^ 
Flanders     ...■■•■■■ "^ ^  --A- 

The  Main  Generators  of  the  U.  b.  a. 
Tennessee — R.    E.    Gilman '»'» 

The  Nerve  Center  of  the  Battleship  Ten- 
nesse.^C.    B.    Mills ,. Vir^T 

Operating  Data-Installation  and  Mainte- 
nance of  Automatic  Substations— C.  A. 
Butcher     -■-••- oQrt 

Question  Box.  Nos.  1986-1987 290 


JULY 

Stray    Losses    in    Converters— F.    D. 

Newbury    .;;   v;    Vr"  i mi 

Power  Transmission— F.  C.  Hanker.-,     iai 
Stray     Losses     in     60-Cycle     Synchronous 
Booster  Converters— F.  T.  Hague...    ......     292 

The  Automatic  Electric  Bake  Oven— John 
M.   Strait  and  J.   C.  Woodson..................     -Jat" 

Electrically   Operated   Grain  Car   Unload- 

ers— R.  T.  Kintzing : - ••     ^"' 

Some   Features    of   the    Cottiell    Plant   at 

the  Hayden  Smelter-C.  G.  Hershey....^     304 
Transmission  Line  Circuit  Constants  and 
Resonance— R.    D.    Evans    and    H.     K.. 

Sels    " ^'"' 

Starting    Characteristics    of    Synchronous 

Motors— E.    B.    Shand  ^^^rry^- 

Cleaning     Surface     Condenser     Tnbes— U. 

W.  R.  Morgan •— <*" 

Methods    of    Magnetic    Testing— Thomas     ^^^ 

Spooner    v;'"'«""Vi"'"*j lo'i 

Voltage  Transformers— E.G.   Reed............     i-i 

Operating  Data— Installation  of  Switch- 
ing Equipment  for  Synchronous  Con- 
verter    Substations- A.    J.    A.    Peterson     329 

Question  Box.  Nos.  1988-1999 .■;...     331 

Railway  Operating  Data— Stopping  a  Car 
by    Braking    with    the    Motors— H.    K.     ^^^ 
Meyer    


The  Gyro  Stabilizer  for  Ships 
Sperry    - 


Question  Box  Service  —  Chas.  R. 
Riker .....^..     336 

The  Gyroscopic  Stabilizer  on  the  S.  i. 
Lyndonia— Alexander    E.    Schein 336 

The  Construction  of  the  Lyndonia  Sta- 
bilizer— W.  T.   Manning ■. - 34^ 

The  Electrical  Equipment  for  the  Lyn- 
donia Stabilizer— T.  P.  Kirkpatrick  and 
H    C    Coleman = 344 

The' Comparison  of  Small  Capacities  by  a 
Beat   Note  Method— P.  Thomas...- 34» 

Methods  of  Magnetic  Testing  (Cent.)  — 
Thomas   Spooner   ^o^ 

Transmission  Line  and  Transformers— 
R    D.  Evans  and  H.  K.  Sels 356 

Excavating  with  Electric  Power  in  the 
Miami  Conservancy  District— L.  C.  Mc- 
Lure — ;; J 

The  Manufacture  of  Copper  Wire  and 
Strand— R.    Kennard   .-. ;•.-     361 

Electrical  Characteristics  of  Transmis- 
sion Circuits— XV — Synchronous  Motors 
and  Condensers  for  Power-Factor  Im- 
provement—Wm.  Nesbit  - 365 

Question  Box.  Nos.  2000-2031  v;".;- 

Railway  Operating  Data— Tinning  Malic- 
able  Iron  Bearing  Shells— J.  S.  Dean....     380 


SEPTEMBER 

The    Association    of    Iron    and    Steel 
Electrical     Engineers  —  Ernest     J. 

Jefleries    ; •..■■••■•     ^81 

The  Function  and  Limitations  ot  In- 
sulation—B.  G.  Lamme ■■ 382 

Electrical    Developments    in    the   Iron 

and  Steel  Industry— R.  B.  Gerhardt     383 
Dependable     Driving     Equipment— G. 

E.    Stoltz .-•■:     384 

Mechanical      Maintenance      of      Mill 

Equipment— G.  M.  Eaton....... -..     384 

Variable  Speed  Induction  Motor  Sets— O. 

W.  Kincaid   i;.;,—,;,  ■; 

Substations   for   Reversing  Mill   Motors— 

G.   P.   Wilson ••••     O"' 

Electric     Furnace     Gray     Iron— J  as.      L. 

Cawthon,   Jr „-■;:; *^* 

First  Reversing  Mill  Drive  m  This  Coun- 

try— W.    S.    Hall ■■■■■- ^<"' 

Electrical    Transmission    vs.    Coal    Trans- 

portation— Harold    W.    Smith...- 402 

Insulation    for   Steel    Mill    Motors— J.    L. 

Rylander     ^vi-    •,■. -^ii 

Reducing     Mechanical     Difficulties     with 
Motor-Driven       Applications  —  R  a  o  u  I 

Pruger  and  Louis  A.   Deesz -..     40o 

Effect  of   Connecting  a   Generator  to   the 

Line   Out  of  Phase-D.   Goodfellow 413 

Motor  Driven  Plate  Mills-F    D    Egan         414 
Power-Factor  Correction  m   Steel  Mills— 

Hollis    K.    Sels .-... ■•■■"     419 

Railway    Operating    Data— The    Assembly 
ot   Complete  Sets  of  Commutator  Seg- 

ments— John   S.   Dean 4^? 

Question  Box.  Nos.  2032-2041 425 


OCTOBER 

Drive  Home   the   Facts— P.  H.   Gads- 

den     Vi-UV.-:-; ■■- 

The      Necessity      for      Publicity      in 

Business— G.    E.    Tripp •.-     428 

Public     Utility     Financing     for     the 

Future— Allen    B.    Forbes -     4ZS 

The       Transportation      Business —  A 

World  Fundamental— M.  C.  Brush..     430 
The  Problems  of  the  Street  Railways 

—John  H.  Pardee •...■.•     432 

The  Problem  of  Mass  Transportation 

—Edward  Dana  .-; .■•. 434 

The  Outlook  for  the  Next  Five  Years 

Philip  J.   Kealy .-■....■; -..■     435 

The    Development    of    Rapid    Transit 

Lines— Britton  1.  Budd ^JJ' 

Futures— Calvert  Townley   4»B 

The  Trackless  Trolley  or  Trolley  Bus 

— Thos.   S.  ^Vheelwright -..■     439 

Outlook  for  the  Electric  Railway  In- 

dustry-Henry   A.    Blair 440 

Dealing    with    the    Public    and    Em- 

ployes— Harry   Reid    ......•"•.■ 44.! 

The  Relation  of  the  Electric  Railway 
to     the     Community  —  Arthur     W. 

Thompson     ^■.-... -■,■•■     '■'•* 

Illinois    Pioneering    in    Public    Rela- 
tions— Bernard   J.   Mullaney ■'•'= 


The    Standard   Tyi>e3   of    City   Cars—      _^' 
The  Country  Really  Needs  to  Meet 
Traffic   Requirements- W.   H.   Hen- 

lings.  Jr ..•-     447 

Wasting   Capital   in   Bus  CompeUUon 

— Mwin   D.   Dreyfus 448 

(Encourage  Young  Engineers  to  Enter 
-^       Railway       Organizations  —  H.       H. 

Johnson    — — 449 

The  Electric  Railway  and  the  Jitney 

F.  G.    BufTe - -.-     450 

An     Appeal     to     Manufacturers     and 

Dealers— Barron   G.   Collier 462 

Electric    Railway    and    Welfare    Work— 

Joseph  H.  Alexander 463 

The     Problem     ot     Street     Congestion— 

Thomas  Fitzgerald   ....-.--...     457 

Use  and  Abuse  of  Electric  Motors— J.  M. 

Hippie     •.■■■     462 

Shop  Facilities  for  Maintenance  of  Rail- 

way  Equipment— H.   A.  Leonhauscr 464 

Construction     of     Semi-Steel.     Front-En- 

trance  Side-Exit  Cars— M.   O'Brien -     468 

Side  Wear  of   Carbon   Brushes  on  Venti- 

lated  Railway  Motors — J.  S.  Dean _-.     470 

Freight  Service  on  Electric  Railways — T. 

H.  Stoffel  ■• -.—.--     474 

Safety     Car     Operating     Results — C.     L,. 

Doub -■■-••    477 

The  Value  of  Association  of  the  Me- 
chanical Departments  ot  Electric  Rail- 
ways—F.   G.   Hickling 480 

Some  Mechanical   Causes  of  Flashing  on 
Railway  Motors— J.   K.  Stotz  ...........  .....     481 

Railway  Operating  Data— Electric  Weld- 
ing as   a  Factor  in  Reclamation— John 

S    Dean        — 

Question   Box.'Nos.    2042-2046 484 


NOVEMBER 

Electricity   in   the  Textile   Industry— 

J.   R.   Olnhausen - 485 

Electrification  of   New   England  Tex- 
tile  Mills-G.   D.   Bowne^  ■'''.V  v;.-,i     *^^ 
The  Central  Station  and  the  Textile  Mill 

— F.    S.    Root -■     487 

Modernized  Plant  of  Prudential  Worsted 

Company— J.   B.   Parks 488 

The  Textile  Industry  in  the  South— John 

Qelzer    

The     Design     of     Induction     Motors     for 

Textile  Service— O.   C.   Schoenfeld 494 

Individual  Motor  Drive  for  Spinning  and 

Twister  Frames— George  Wrigley 601 

Motors    for    Textile    Finishing     Plants— 

Warren   B.    Lewis ■■"' 

Central  Station   Power   for  Textile  Mills 

—John  W.   Fox •-....■     607 

Adjustable   Speed  Motors   and  Control   in 

Finishing  Plants-C.  W.  Babcock 509 

Silk  Throwing  and  Electric  Drive— C.  T. 

Guilford °" 

Day  and  Night  Lighting  in  Textile  Mills 

—Samuel    G.   Hibben S'* 

Operating    Data— Transformers    for    Syn- 

chronous  Converters— E.  R.   Sampson...     518 
Question  Box.  Nos.  2047-2061 619 


DECEMBER 

The     Development      ot     Our     Water 

Powers— A.   L.  Schieber 5-J 

Hydraulic  pcaction   Turbines— D.   J.   Mc- 

Cormack     "• 

Circle    Diagrams    for    TransmUsion    Sys- 

terns— R.  D.  Evans  and  H.  K.  Sels 530 

The  Dry  Cell  Radio  Vacuum  Tube— Harry 

M.  Ryder *^® 

Changing    Railway    Substations    from    25 

to  60  Cycles— G.  C.  Hccker...- 639 

Electrical  Characteristics  of  Transmission 
Circuits— XVI  —  Phase      Modifiers     for 

Voltage   Control— Wm.    Nesbit o4- 

Methods  ot  Magnetic  Testing    (Concl.)— 

T.    Spooner   

Commutator    Insulation     Failures— J.     L. 

Rylander    - "" 

Railway   Operating   Data— General   Infor- 
mation  on  Grid   Resistance  Design   for 
the  Operating  Man-Haro'  R.  Meyer..-     556 
Question  Box.  Nos.  2062-2075 - 657 


THREE  YEAR  TOPICAL  INDEX 


OF 


The  Electric  Journal 


WITH 


INDEX   TO  AUTHORS 


FOR 


VOL.  XVI  -  1919 
VOL.  XVII  -  1920 
VOL.  XVIII  -     1921 


PUBLISHED  BY 

THE  ELECTRIC  JOURNAL 

PITTSBURGH.  PA. 


OUTLINE  KEY  TO  TOPICAL  INDEX 

VOLUMES  XVI,   XVII  and  XVIII 

THIS  Index,  as  well  as  the  previous  indexes,  is  arranged  according  to  the  topical  classification  of  subjects. 
The  original  scheme  for  this  method  of  indexing  was  published  in  the  Journal  for  February,  1906.  All 
articles  which  have  appeared  in  the  Journal  since  its  initial  issue  can  be  located  quickly  by  the  use  of 
the  Ten-Year  Index,  (1904-1913),  the  Five- Year  Index,  (1914-1918),  and  the  present  Index,  which  covers  the 
first  three  years  of  the  fourth  pentad.  (^. 

Abbreviations:  T — Number  of  Tables;  C — Number  of  Curves;  D — Number  of  Diagrams;  / — Number  of  Illustrations;  W — 
Number  of  Words;  QB — Question  Box;  EN — Engineering  Notes;  EH — Industrial  Applications  of  Electric  Heaters; 
OD — Operating  Data  for  Converting  Substations ;  ROD — Railway  Operating  Data.  (The  numerals  following  EN, 
EH,  OD  and  ROD  are  volume  and  page  numbers.)     The  main  headings  and  sub-divisions  are  as  follows: — 


Steam 


MECHANICAL  ENGINEERING 

3       Brakes    3      General     . 


ELECTRICAL  ENGINEERING 


GENERAL 


Materials — Insulation    3 

Measurements — Meters — Relays    3 

Theory    4 

GENERATION 

Power   Plants — Substations 4 

Dynamos  and  Motors — Armatures — 
Bearings  —  Commutators  —  Field 
Windings    4 

Direct  Current — Shunt  and  Com- 
pound— Series — Commutating    Pole.  4 

Alternating  Current — Alternators — 
Synchronous  Motor  s — Induction 
Motors  —  Series       Motors  —  Fan 


Motors    5 

n.\TTERIES    5 

TRANSFORMATION 

Rectifiers  6 

Rotary  Converters  6 

Storage  Batteries  6 

Transformers — Windings  —  Connec- 
tions —  Performance — Series — Auto- 
transformers — Reactance  Coils — Oils  6 
Condensers    6 

TRANSMISSION,  CONDUCTORS 

AND  CONTROL 

General  — Systems   7 


Lines  —  Overhead  —  Underground — 
Conductors 7 

Switchboards — Interrupting     Devices 
— Protective    7 

Regulation  and  Control — Regulators 
— Controllers — Rheostats    7 

UTILIZATION 

General — Electrochemistry     S 

Lighting  8 


Power — Motors  and  Applications — 
Heating  Apparatus — Welding — Mag- 
nets     8 

Intelligence  Transmission  9 


RAILWAY  ENGINEERING 


General   9 


Motive    Power— Locomotives — Cars —         Mining 
Maintenance  and  Repairs 10 


MISCELLANEOUS 

General — Works   Management 11       The  Engineer — Education 11      The  Journal, 


INDEX    TO    AUTHORS 

(pp.  12-16) 


THE  JOURNAL  QUESTION  BOX 

References  in  the  Index  to  the  Journal  Question   Box  are  given  by  numbers.     The  questions  and  answers 
during  1919,  1920  and  1921  appeared  as  follows : 

1919  1920                   1921                                                                                 1919                    1920  1921 

JANUARY                                                    1686-1695         1840-1848         1946-1961        JULY     - .'-    1899-1903  1988-1999 

FEBRU4RY                                                 1696-1710         1S49-1851         1962-1974        AUGUST    1773-1782  1904-1911  2000-2031 

MABCH                .                                  .      1711-1723         1852-1862         1975-1981        SEPTEMBER 1783-1806  1912-1915  2032-2041 

APRIL                                                     .      a724-1740         1863-1874         1982-1985       OCTOBER    1807-1814  1916-1917-1923  2042-2046 

MAY                                                                 1741-1748         1875-1876          NOVEMBER    1815-1826  1918-1920  2047-2061 

JUNE                                          _  .               1749-1772         1877-1898         1986-1987        DECEMBER     1827-1839  1921-1945  2062-2075 


MECHANICAL    ENGINEERING 


Hydraulic  Reaction  Turbines— D.  J.  Mc- 
Cormack.  C-2.  1-15,  W-3150.  Vol.  XVIII.  p. 
524,  Dec,  '21. 

Methods  of  Computing  Machinery  Founda- 
tions—W.  H.  Gilleland  and  A.  H.  CunninK- 
ham.  T-1,  C-2,  D-13,  1-8,  W-3830.  Vol. 
XVII,   p.    387,   Sept.,   '20. 

Computing  Machinery  Foundations  —  QB, 
1921. 

Manufacture  of  Six-Inch  High-Explosive 
Shells- T.  D.  Lynch.  1-23.  W-3600.  Vol. 
XVI.   p.   17.  Jan.,  '19. 

(E)  H.  P.  Davis.     W-390,  p.  7. 

Bakelite  Micarla  Airplane  Propellers— N.  S. 
Clay.  C-1,  1-6,  W-2400.  Vol.  XVI,  p.  482, 
Nov..  '19. 

(E)   R.   P.  Jackson.     W-270.  p.  469. 

Water   Wheel    Governor— QB.    1807. 

Capacity   of  Air  Pump — QB.  1974. 

GEARS 

Decreased  Operating  Costs  With  Helical 
Gears— G.  M.  Eaton.  1-2,  W-3000.  Vol.  XVI. 
p.   430.   Oct..   '19. 

BRAKES 

Air  Brakes  in  Electric  Traction— S.  W.  Dud- 
ley. C-7.  D-1.  1-24.  W-7425.  Vol.  XVII.  p. 
540.   Dec,    '20. 


Klectric  Braking  of  Direct-Current  Vehicles 
— W.  M.  Hutchison.  D-5,  W-160U.  Vol.  XVII. 
p.   471,  Oct.,   '20. 

Dynamic  Braking  of  a  Single-Phase  Motor— 
QB,  1941. 

Magnetic  Brakes— QB,  2029. 

STEAM 

Heat  Balance  Systems  F.  C.  Chambers  and 
J.  M.  Drabellc.  D-2.  1-3.  W-2680.  Vol.  XVIII, 
p.  233.  May.   '21. 

Fuel  Burning  Kquipment  of  Modern  Power 
Stations— J.  G.  Worker.  C-1.  1-13.  W-2030. 
Vol.  XVT.  p.  ."-iS.  Feb..  "ID. 

Size  of  Exhaust  Pipe— QB.   1769. 

Wire    Drawing     QB.    1777. 

Boiler   Gaskets— QB.   1785. 


Turbines 

Large  Steam  Turbine  Design— J.  F.  Johnson. 
T-1.  C-1.  D-1.  L2.  W-6I20.  Vol.  XVI,  p.  33. 
Jan..   '19. 

Turbine  Gear  Drive  for  Torpedo  Boat  Dc- 
stroyers— W.  B.  Flanders.  T-2.  C-1.  1-5, 
W-Iino.      Vol.    XVI.    p.   474.   Nov..    '19. 

Steam   Turbines   for  Mechanical  Drive     Ivan 


S.  Fordo.  1-6,  W-2700.  Vol.  XVII,  p.  13«. 
Apr..  '20. 

(E)   Chas.   R.  Riker.     W-260,  p.   127. 

Main  Turbines  and  Turbine  Speed  Conlrol 
for  the  U.  S.  S.  Tennessee- -W.  B.  Flanders. 
1-7.  W-2060.     Vol.  XVIII.  p.  281.  June.  '21. 

Lighting  Sets  on  the  V.  S.  S.  Tennessee— J. 
A.  MacMurchy  and  Albert  O.  Loomis.  1-2. 
W-1890.      Vol.    XVIII.    p.    271.   June.   '21. 

Lubrication  of  Steam  Turbine  Bearings— H. 
V.  Schoepnin.  I-l.  W-350.  Vol.  XVII.  p.  90, 
March,   '20. 

Erosion  of  Turbine  Blades- QB.  2041. 

Condensers 

Application  of  Steam  Condensers — Selection 
of  Type— F.  A.  Burg.  D-2.  1-4,  W-3876.  Vol. 
XVll.  p.   683.   Dec.   '20. 

Selection  of  Size  of  Sleam  Condensers— F. 
A.  Buri;.  T-3.  C-3.  W-1950.  Vol.  XVIII.  p. 
17.  Jan..  '21. 

Cleaning  Surface  Condenser  Tubes  -  D.  W. 
R.  Mor>:on.  T-1.  C-3.  1-4.  W-1200.  Vol.  XVIII. 
p.   313.   July.   '21. 

Condensing  Equipment  and  Oil  Cooling  Sys- 
tem for  the  U.  S.  S.  Tennessee  John  H. 
Smith  and  Albert  O.  Loomis.  T-1.  1-8. 
W-3480.     Vol.  XVIII,  p.  273.  June,  '21. 


ELECTRICAL    ENGINEERING 

GENERAL 


Post-War  Engineering  Problems— C.  E.  Skin- 
ner.      (E)    W-470.      Vol.    XVI,   p.    1,   Jan.,    '19. 

What  the  Utilities  Have  Gained— E.  H. 
Sniffin.     (E)  W-300.     Vol.  XVI,  p.  1,  Jan.,  '19. 

Post-War  Industrial  Reconversion- J.  M. 
Curtin.     (E)   W-1050.  Vol.  XVI.  p.  2.  Jan.,  '19. 

A  Central  Station  Opportunity— Guy  E. 
Tripp.  (E)  W-1300.  Vol.  XVI,  p.  46, 
Feb.,   '19. 

Pooling  Our  Resources— A.  H.  Mclntire. 
(E)    W-600.     Vol.   XVI,  p.    113,  Apr.,   '19. 

Immediate  Economic  Aspects  of  the  Electric 
Supply  Industry— J.  D.  Mortimer.  (E)  W-670. 
Vol.   XVI.   p.    163.   May.   '19. 

Water  Powers— F.  Darlington.  (E)  W-1620. 
Vol.   XVI.   p.   164.   May.  '19. 

The  Significance  and  the  Opportunities  of 
the  Central  Station  Industry— R.  F.  Schu- 
chardt.  (E)  W-1860.  Vol.  XVI,  p.  166, 
May,  '19. 

The  Primaries  of  Today  the  Secondaries  of 
Tomorrow— W.   S.  Murray.      (E)    W-24S0.    Vol. 

XVI.  p.   168.  May.  '19. 

Central  Station  Profit  Sharing— Wm.  C.  L. 
Eglin.      (E)    W-520.     Vol.  XVI,  p.  170,  May.  '19. 

The  Engineer  and  the  Community — E.  H. 
Sniffin.     W-2520.     Vol.  XVI.  p.  249.  June.  '19. 

Research  and  Manufacturing — P.  G.  Nut- 
ting.    (E)      W-650.     Vol.  XVII.  p.  127.  Apr..  '20. 

EUeet  of  Electrical  Removal  of  Limitations — 
Guy  E.  Tripp.  (E)  W-1150.  Vol.  XVII.  p. 
174.  May.  '20. 

The  Greatest  Development  in  Electrical  His- 
tory—Milan    R.     Bump.       (E)      W-1050.       Vol. 

XVII.  p.    175.   May.    '20. 

Sound  Central  Station  Policies— Joseph  B. 
McCall.  (E)  W-O.'iO.  Vol.  XVII.  p.  170. 
May.  '20. 

The  Water  Power  Situation— Franklin  T. 
Griffith.  IE)  W-650.  Vol.  XVII.  p.  177. 
May,   '20. 

Some  Figures  Electrical- A.  H.  Mclntire. 
(E)   W-1000.     Vol.  XVII,   p.   233,  June.  "20. 

International  Standardization— C.  E.  Skin- 
ner. (E)  W-450.  Vol.  XVII.  p.  277.  July.  '20. 
July.  '20. 

The  Water  Power  Bill— E.  H.  Sniffin.  (E) 
W-500.      Vol.   XVII.   p.   319.   Aug..   1920. 

Public  Utility  Eeonomics-G.  E.  Tripp.  (E) 
W-1300.     Vol.   XVIII.  p.   1.  Jan..  '21. 

A  Perspective  View— E.  H.  Sniffin.  (E) 
W-1000.     Vol.   XVIII.   p.  2.  Jan.,  '21. 

Present  Trend  of  Electrical  Development — 
John  J.  Gibson.  (E)  W-950.  Vol.  XVIII.  p. 
4.  Jan.,  '21. 

The  Electrification  of  Industry- J.  M.  Cur- 
tin. (E)  W-480.  Vol.  XVIII,  p.  5, 
Jan..  '21 . 

The  Utilities  Situation— Milan  R.  Bump. 
(E)   W-7S0.     Vol.   XVIII.  p.  159,  May,   '21. 

Some  Thoughts  in  Connection  with  the  Sale 
of  Stock  to  Customers— John  F.  Gilchrist.  (E) 
W-1400.      Vol.    XVIII,   p.    161.   May.    '21. 

Conserving  Capital  and  Natural  Resources- 
Edwin  D.  Dreyfus.  IE)  W-1020.  Vol.  XVIII, 
p.    163,  May,    '21. 

The  Use  of  Central  Station  Power  by  In- 
dustrial Plants -Brent  Wiley.  (E)  W-850. 
Vol.   XVIII.  p.   164,   May,  '21. 

The  Central  Station  Company  as  a  Com- 
munity Asset— A.  M.   Lynn.      (E)  W-780.    Vol. 

XVIII.  p.   167,   May.   '21. 


An  80-Mile  Central  Station  Bus- C.  S.  Cook. 
(E)   W-600.     Vol.  XVIII.  II.   166.  May.   '21. 

The  Pittsburgh  Power  Zone  A.  H.  Mclntire. 
(E)   W-1750.     Vol.   XVIII.  p.   165.  May.   '21. 

Water  Power  Developments- Daniel  W. 
Mead.      W-5100.     Vol.   XVIII.  p.  224.   May.   "21. 

The  Development  of  Our  Water  Powers— A. 
L.  Schieber.  (E)  W-850.  Vol.  XVIII.  p.  623. 
Dec.   '21. 

Public  Utility  Financing  for  the  Future — 
Allen  B.  Forbes.  (E)  W-1900.  Vol.  XVIII. 
p.  428.  Oct.,   '21. 

The  Necessity  for  Publicity  in  Business  G. 
E.  Tripp.  (E)  W-700.  Vol.  XVIII,  p.  428, 
Oct..   '21. 

Illinois  Pioneering  in  Public  Relations- 
Bernard  J.  Mullnnoy.  (E)  W-1600.  Vol. 
XVIII.  p.  445.  Oct..  '21. 

Some  Labor  Conditions  in  Foreign  Countries 
— W.  G.  McConnon.  W-2750.  Vol.  XVIII.  p. 
102.  Mar..  '21. 

MATERIALS 

Methods  of  Testing  for  Hardness — Dean  Har- 
vey. T-1.  1-2.  W-1900.  Vol.  XVI.  p.  264. 
June.  '19. 

Laminated  Iron  in  Electric  Motors — M.  S. 
Hancock.  W-1720.  Vol.  XVI.  p.  338. 
Aue..    '19. 

The  Relation  Between  Gases  and  Steel— H. 
M.  Ryder.  C-6.  1-3,  W-2700.  Vol.  XVII.  p. 
161.  Apr..  '20. 

The  Protection  of  Iron  from  Corrosion — 
Leon  McCullouch.  W-4100.  Vol.  XVII.  p. 
288.  July.  '20. 

Copper — A  Delicate  Material — N.  B.  Pilling. 
C-2.  1-8.  W-1400.  Vol.  XVII,  p.  320. 
Aug..   '20. 

The  Handling  of  Copper— ROD.  XVIII.  76. 

The  Development  of  Magnetic  Materials— T. 
D.  Yenscn.  W-2700.  Vol.  XVIII,  p.  93. 
Mar..   '21. 

The  Manufacture  of  Copper  Wire  and 
Strand— R.  Kennard.  I-IO.  W-2500.  Vol. 
XVIII,  p.   361,  Aug.,   '21. 

Insulation 

The  Story  of  the  Insulations- C.  E.  Skinner. 
W-6200.     Vol.  XVII,  p.  139,  Apr.,  '20. 

The  Function  and  Limitations  of  Insulation 
— B.  G.  Lamme.  IE)  W-1150.  Vol.  XVIII.  p. 
882.   Sept..   '21. 

Electrical  Insulating  Materials-  R.  P.  Jack- 
son.    W-7500.     Vol.  XVI.  p.  326.  Aug..  '19. 

Insulation  for  Steel  Mill  Motors  J.  L.  Ry- 
landcr.  1-2.  W-2nOO.  Vol.  XVIII.  p.  405, 
Sept.,  '21. 

Use  of  Mica  Insulation  for  Alternating- 
Current  Generators  H.  D.  Stephens.  1-7. 
W-2260.     Vol.    XVI,   p.  91.   Mar.,   '19. 

Safe  Operating  Temperatures  for  Mica  Insu- 
lation -11.  D.  .Stephens.  T-1,  1-2,  W-1750.  Vol. 
XVI.  p.  131,   Apr.,  '19.  . 

The  Thermal  Conductivity  of  Insulating  and 
Other  Materials  T.  S.  Taylor.  T-6,  r-4,  1-2. 
W-4300.     Vol.  XVI.  p.  526.  Doc.  '19. 

Conduction  in  Liquid  Dielectrics — J.  E. 
Shrader.  C-8.  D-1.  I-l.  W-2500.  Vol.  XVI.  p. 
834.   Aug..  '19. 


Moulded  Insulation- W.  H.  Kempton.  Se- 
lection and  Application.  W-32a0.  Vol.  XVI. 
p.   84.  Mar..   '19. 

Designing  Moulded  Insulation- W.  H.  Kem|v 
ton.  1-19.  W-2970.  Vol.  XVI.  p.  152. 
Apr..  '19. 

The  Insulation  of  Distribution  Transformers 
—A.  C.  Farmer.  1-15.  W-3000.  Vol.  XVI.  p. 
223.   May.   '19. 

Vacuum  and  Heat  Treatment  of  InioUlIng 
Materials- J.  E.  Shrnder.  T-1.  C-6.  1-2. 
W-2300.      Vol.   XVII.   p.    157.   Apr..   '20. 

For   Generator  Terminals     QB.    1767. 

For  Magnetism- QB.    1797. 

Transparent  Noninflammable  Sheet  ln«ul>- 
tor— QB,  1848. 

Insulating   Varnishes     QB,   1S63. 

Insulation  of  ^urbo-Alternator  Field-QB. 
18S6.  -• 

Effects  of  Teiniieralure  on  Insulation- QB. 
1900. 

Burning  Insulation  from  Motor  Windings— 
QH.    1909. 

Insulation  Resistance —QB.  1963. 

Shellac— QH.  2005. 

Cementing    Flexible    Insulation— QB.    2024. 

Special  Motor  Insulation  for  Tropical 
Countries— QH.  2069. 

INSULATORS 

The  Design  of  Transmission   Line  Insulators 

— G.  I.  Gilchrist  and  T.  A.  Klinefelter.  Theo- 
retical considerations.  Practical  applications. 
T-4.  1-27.  W-5000.     Vol.  XVI.  p.  8.  Jan..   'IS. 

(E)   Chas.  R.  Riker.     W-190.  p.  7. 

Testing  Insulators  in  Factory  and  Field— 
I-eslie  N.  Crichton.  T-1.  C-1.  1-9.  W-1600.  Vol. 
XVII.  p.  506.  Nov..  '20. 

Healing  of  Insulators  -QB.   1844. 

MEASUREMENT 

The  Power  Indicating  and  Limiting  Appa- 
ratus— For  the  Chicago.  Milwaukee  &  St.  Paul 
Railroad— B.    H.    Smith.      I-IO.    W-2700.      Vol. 

XVII.  p.  42.  Feb..  '20. 

Methods  of  Magnetic  Testing— Thof. 
Spooner.      T-3.    C-12.    D-0.   I-S.   W-13760.      Vol. 

XVIII.  II.  316.  July.  '21  ;  p.  351.  Aug..  '21  ;  p. 
548.   Doc.    '21. 

The  Comjiarison  of  Small  Capacities  by  a 
Beat  Note  Method -P.  Thomas.  T-2.  W-12S0. 
Vol.   XVIII.  p.  349.   Aug..  '21. 

3-Ph.  Current  with  2  Current  Traniform«ri 
-QH.    1698. 

Testing   Power-Factor  Meter-  QB.   1745. 

Relative  Merits  of  Slop  Watches     QB.   1947. 

Potentiometer  Leads  -QB.   1999. 

Meters 

Switchboard  Meter  Connections  for  Alter- 
nating-Current Circuits— J.  C.  Group. 

I General— Single-phase.  Thrw-Wirc  Cir- 
cuits. T-1.  C-3.  D-9.  W-3760.  Vol.  XVII.  p. 
25.   Jan..   '20. 

(E)  A.  H.  Mclntire.     W-600,  p.  2. 

II.— Two-Phase  Circuits.  D-13,  W-3700.  Vol. 
XVII.  p.   61.   Feb..  '20. 

III.—Thrcc-Phase.  Three-Wire  Circuits.  D-17. 
W-S400.    Vol.  XVII.  p.  99.  Mar..  '20. 


THE  ELECTRIC  JOURNAL 


IV.— Single-Phase  Wattmeters  on  Three- 
Phase,  Three-Wire  Circuits— C-2,  D-16.  W- 
2650.     Vol.   XVII.  p.  131,   Apr..    '20. 

V— Three-Phase.  Four-Wire  Circuits.  D-8. 
W-3000.     Vol.  XVII,  p.   219,  May,  '20. 

VI. — Six-Phase  Circuits — Measurements  of 
Reactive  Volt  Amperes  in  Two-Phase  rircuits. 
D-6,  W-1660.     Vol.  XVII,  p.   251,  June,  '20. 

VII.  and  VIII.— Measurins  Reactive  Vol» 
Amperes  in  a  Three-Phase.  Three-Wire  Cir- 
cuit. D-16.  W-3100.  Vol.  XVII,  p.  281.  July  ; 
p.  355,  Aug.,  '20. 

IX Synchronizing:    with     Lamps — D-2,     1-4, 

W-1S50.     Vol.   XVII.  p.  536,  Nov.,   '20. 

X. — Synchronizinp:  with  Synchronoscopes — J. 
C.  Group.  D-13,  W-2650.  Vol.  XVII.  p.  667. 
Dec.  '20. 

The  New  Portable  Oscillograph  as  Applied 
to  Commercial  Work — J.  W.  Legff.  C-4,  1-5, 
W-3375.     Vol.  XVII,  p.  663,  Dec,  '20. 

(E)    R.   P.   Jackson.     W-450,  p.   639. 

Standardization  of  Electric  Indication  In- 
struments for  Use  with  Radio  Apparatus — G. 
Y.  Allen.  T-1,  C-1,  1-13,  W-4000.  Vol.  XVI, 
p.  494,  Nov.,  '19. 

The  Stability  Indicator  for  the  U.  S.  S. 
Tennessee — R.  T.  Pierce.  D-1.  W-790.  Vol. 
XVIII.  p.  280,  June,  '21. 

The  Electrostatic  Glow  Meter — R.  J.  We»- 
sley.  1-4,  W-400.     Vol.  XVI.  p.  228,  May,  '19. 

Metering  Low  Power-Factor  Load — QB,  1881. 


Electrostatic  Ground  Detector — QB,   1940. 

Metering  Load  on  Secondary  of  Taylor  Con- 
nections— QB,    1952. 

Connections  of  Reactive  Meter- QB,  1967. 

Calibrating  A.  C.  Meters  with  Potentio- 
meter— QB,   2035. 

Calibrating  Frequency  and  Power-Factor 
Meters— QB.  2044. 

Connections  for  Power-Factor  Meter — QB. 
2062. 

VOLTMETERS   AND  AMMETERS 

Measuring  Three-Phase  Voltage  with  One 
Meter— QB,  1866. 

Measuring  Three-Phase  Current  with  One 
Meter— QB,   1866. 

Amalgamation  of  Mercury  in  Ampere-Hoar 
Meters— QB,   2058. 

WATTMETERS 
The  Thermal   Storage   Demand  Wattmeter — 

Its  Characteristics  and  Applications — Paul  M. 
Lincoln.  C-1,  D-2,  1-3,  W-2850.  Vol.  XVII,  p. 
263,    June.    '20. 

Testing  Constant— QB.  1762. 

Transformer    Connections— QB.    1787. 

Measuring  Thrcc-Phasc  and  One-Phase— 
QB.  1791. 

Lightning    Protection    for    Meters— QH.    182.i. 

Frequency  Range  of  Induction  Type — QB, 
1919. 

For  Forward  and  Reverse  Power-    QB.   1928. 

Constant  with  Current  Transformer — QB, 
1932. 

Transformer  Connections — QB,  1934. 


Changing  Dial  Constants — QB,  2003. 

Reversal  at  Low  Power-Factor— QB.  2074. 
SYNCHRONOSCOPES 

Connections  for  Synchronoscope — QB,  2065. 
RELAYS 

Typical  Relay  Connections- Lewis  A.  Ter- 
ven.  D-11,  1-14.  W-7830.  Vol.  XVIII,  p.  29. 
Jan.,  21  ;  p.  61,  Feb..  '21  ;  p.   99,  Mar..   '21. 

Reverse  Power  Relay  Connections— QB,  1824. 

Overload  Alarm— QB,  1873. 

Differential  Relay  Around  a  Star-Delta 
Transformer— QB.    1943. 

Pitting  of  Contacts— QB.   1962. 

Z  Connection— QB,  2063. 

Cross   Connected    Relay  System — QB,   2072. 


THEORY 

The  Flow  of  Power  in  Electrical  Machines. 
J.  Slepian.  D-23,  W-7260.  Vol.  XVI,  p.  303, 
July,  '19. 

Why  High  Frequency  for  Radiation?  J. 
Slepian.  I-o.  W-2250.  Vol.  XVIII.  p.  129. 
Apr.,  '21. 

Resistance  in  Series  Multiple— QB.   1744. 

Insulation    of    Magnetism— QB,    1797. 

Pounds— Feet-Torque — QB.  1814. 

Static  Discharge  -QB.   1821. 

Difference  Between   Kw  and  Kv-a— QB.  1882. 

Changing  Frequency  by  Induction  Motor — 
QB.   1923. 

Capacity  Susceptance — QB,   2028. 

Voltage  Drop  Across  Reactance  and  Resist- 
ance— QB,  2068. 


POWER  PLANTS 


Heat  Balance  Systems — F.  C.  Chambers  and 
J.  M.  Drabelle.  D-2,  1-3,  W-2680.  Vol. 
XVIII.  p.  233,  May.  '21. 

DESCRIPTION 

Sixty  Thousand  Kw  Turbine-Generator  In- 
stallation- W.  S.  Finlay,  Jr.  At  the  74th 
Street  Station  of  the  Interborouprh  Rapid 
Transit  Company.  D-1,  1-23,  W-6260.  Vol. 
XVI.   p.   172.  May,   '19. 

(E)  E.  H.  SnifRn.     W-170,  p.  171. 

Generating  System  of  the  West  Pcnn  Power 
Company— G.  G.  Bell.  C-2.  1-16,  W-8660.  Vol. 
XVIII.   p.   176,   May,   '21. 

The  Power  Stations  of  the  Duqucsne  Light 
Company— J.  M.  Graves.  T-1,  C-2,  D-1.  1-14, 
W-10610.     Vol.   XVIII.  p.   193.  May.   '21. 

Load  Dispatching  System  of  The  Philadel- 
phia Electric  Company— George  P.  Rou.x.  C-1. 
1-7.   W-2650.      Vol.  XVI.    p.   470.    Nov.,    '19. 

(E)    E.  C.   Stone.     W-660,  p.  469. 

SUBSTATIONS 

Automatic  Substation  Equipment — R.  J. 
Wensley.  D-2,  1-8,  W-2350.  Vol.  XVL  p.  218, 
May,  '19. 

Value  of  Automatic  Railway  Substations  to 
Central  Stations— C.  F.  Llovd.  (E)  W-600. 
Vol.  XVI,  p.  171.  Mav    '19.  ■ 

Substation  Switching  Equipment  of  the  Chi- 
cago. Milwaukee  &  St.  Paul  Railroad— C.  M. 
McL,  Moss.  1-8,  W-1250.  Vol.  XVII.  p.  15, 
Jan..   '20. 

Changing  Railway  Substations  from  25  to 
60  Cycles— G.  C.  Hecker.  T-1.  W-27B0.  Vol. 
XVIII,  p.  539,  Dec,  '21. 

Installation  and  Maintenance  of  Automatic 
Substations— OD.  XVIII,  289. 

Substations  for  Reversing  Mill  Motors— G. 
P.  Wilson.  I-IO.  W-4860.  Vol.  XVIII.  p.  S89. 
Sept.,    '21. 


DYNAMOS  AND  MOTORS 
General 

Efficiency  of  Adjustable  Speed  Motors— R. 
W.  Owens.  D.  C.  motors  with  shunt  field 
armature  resistance  and  armature  voltage  con- 
trol. Induction  motors  with  secondary  resist- 
ance and  pole  change  control.  Small  steam 
turbines.  T-2,  C-6,  W-2600.  Vol.  XVIII.  p. 
11.  Jan..  '21. 

Reducing  Mechanical  Difficulties  with  Motor- 
Driven  Applications— R.  Pruger  and  L.  A. 
Deesz.  1-9.  W-4050.  Vol.  XVIII,  p.  408. 
Sept..   '21. 

(E)  G.  M.  Eaton.     W-400,  p.  384. 

Use  and  Abuse  of  Electric  Motors— J,  M. 
Hippie.  T-1.  W-1250.  Vol.  XVIII.  p.  462, 
Oct.,    '21. 

Windag<^QB.  1815. 

Burning   Off   Insulation— QB.   1909. 

Numbers  on  Armature  Shaft— QB,  2030. 


GENERATION 

(AND   ALL   PARTS   OF   ROTATING   MACHINES) 

ARMATURES 

(except  commutators) 

Armature  Wedges — V.  3.  Aimutis.  I-l. 
W-1900.     Vol.  XVI,  p.   524,   Dec.   "19. 

Winding  Railway  Motor  Armatures — J.  B. 
Stiefel.  1-6.  W-2300.  Vol.  XVII,  p.  486, 
Oct..  '20. 

Some  Points  on  Dipping  and  Baking  of 
Railway  Motors— J.  M.  Labberton.  C-1,  W-660. 
Vol.   XVII,   p.   491,    Oct..   '20. 

Armature  Testing     ROD,   XVI,  76. 

Locating  and  Repairing  Armature  Winding 
Troubles -ROD.   XVI.  230. 

Does  it  Pay  to  Dip  and  Bake  Armatures — 
ROD.  XVI.  p.  467. 

Broken  Armature  Leads— ROD,  XVII,  p.  81. 

Armature     Record     Tags— ROD.     XVIII,     p. 


Breaking    of    Commutator    Leads— QB.    1704, 

Armature  Winding  Diagrams  for  Railway 
Motors      ROD.  XVII.   p.   499. 

Testing    Transformers— QB,    1706,    1898. 

Fibre  Wedges— QB.  1737. 

Reconnecting  tor  Half  Voltage— QB.  1738. 
2042. 

Changing  Motor  to  Generator — QB,   1760. 

Coil  Shape— QB.   1803. 

Banding  Wire— QH.  1806. 

Reconnecting  500  Volt  for  125  Volt — QB, 
1808. 

Direction  of  Rotation  of  Progressive  end 
Retrogressive  Windings — QB.  1874. 

BEARINGS 

Railway  Motor  Bearings — J.  S.  Dean.  1-18, 
W-900.     Vol.  XVI,  p.  443.  Oct.,  '19. 

Mounting  and  Care  of  Small  Ball  Bearings 
for  Maximum  Service  George  U.  Bott.  W- 
1400.      Vol.   XVII.  p.   322.   Aug.,   '20. 

Expanding  Bronze  Bearings— C.  M.  Cross. 
I-l.  W-1170.     Vol.   XVll.  p.   4,';2.  Oct..   '20. 

Repairing  Loose  Housings  on  Split  Frame 
Motors— ROD.  XVII.  p.   36. 

Checking  Armature  and  Axle  Bearing  Wear 
ROD.  XVIII.  380. 

Tinning  Malleable  Iron  Bearing  Shells— 
ROD.  XVIII.  380. 

BRUSHES 

Commutator  Brushes  for  Synchronous  Con- 
verters—R.  H.  Newton.  1-2.  W-1050.  Vol. 
XVIII.   p.   61.    Feb.,   '21. 

Side  Wear  of  Carbon  Brushes  on  Ventilated 
Railway  Motors— J.  S.  Dean.  T-2.  1-16,  W- 
2650.      Vol.    XVIII,    p.    470,    Oct..    '21. 

Bronze  Deposited  on  Collector  Ring 
Brushes— QB.   2061. 

COMMUTATORS 

Commutator  Insulation  Failures  J.  L.  Ry- 
lander.     W-1750.     Vol.  XVIII.  p.  5.i4.  Dec.  '21. 

The  Assembly  of  Complete  Sets  of  Commu- 
tator Segments— ROD.  XVIII,  424. 

Blue   Commutator— QB.    1726. 

Undercutting  Mica — QB.   1754. 

Commutation  Trouble — QB,  1867. 


Commutation    of    Ridgeway    Generators — QB. 
1857. 
Equally  Divided  Burned  Spots— QB,  1912. 
Ring    Fire— QB.    1929. 
Use  of  Emery  Cloth— QB,  1933. 
Commutator  Troubles — QB.  2025. 

FIELD  WINDINGS 

Testing  Motor   Fields- ROD.   XVI,   110. 

Field  Winding  Diagrams  for  Railway  Motors 
—ROD.  XVII,  272.  358  and  428. 

Lightning  Arresters  to  Absorb  Inductive 
Kick— QB.    1772. 

Short  Circuited  Turns- QB,  1901. 

Insulation  of— QB.   1886. 

Testing  Polarity— QB,   1740. 

Changing  Scries  to  Shunt  Field- QB.  1922. 

SHAFTS 

Removing  and  Replacing  Railway  Armature 
Shafts— ROD.   XVI,   811. 

Shaft    Currents— QB.    1798. 

Design  of  Shafts— QB,  1894. 

Bent  Shaft— QB,  2016. 


Direct  Current 

Effect  of  Voltage  Variations  on  the  Charac- 
teristics of  Direct-Current  Motors— M.  S.  Han- 
cock. T-1,  (-2,  W-2676.  Vol.  XVII.  p.  572, 
Dec,   "20. 

(E)    Chas.   R.   Riker.     W-450,   p.   639. 

Voltage  Fluctuations  Cause  Trouble — QB, 
1960. 

Voltage  Relations  in  Direct-Current  Ma- 
chines—R.  E.  Ferris.  C-1.  1-19,  W-8160.  Vol. 
XVIII.  p.   32.  Jan.,   '21. 

Reversal  of  Voltage— QB,    1722. 

Reversal  of  Polarity— QB.    1748,    1768. 

SHUNT  AND  COMPOUND 

Performance  of  Motor-Generator  Sets  for  the 
Chicago.  Milwaukee  &  St.  Paul  Ry.— F.  T. 
Hague.  T-1.  C-5.  1-6.  W-3580.  Vol.  XVI,  p. 
47.  Feb.,  '19. 

3000  Volt  Motor-Generator  Sets— For  the 
Chicago.  Milwaukee  &  St.  Paul  Railroad- 
David  Hall.  T-2.  C-6.  1-3.  W-1660.  Vol. 
XVII.  p.  12.  Jan..  '20. 

Ratio  of  Shunt  to  Series  Ampere  Turns — 
QB.    1724. 

Parallel  Operation- QB,   1761.   1782.   1866. 

Shifting  Brushes  with   Load— QB,    1778. 

Unstable  Speed  of  Compensated  Motors — 
QB.  1972. 

Duplex  Windings— QB.  1983. 

Ratio  of  Field  Turns  and  Armature  Turns — 
QB.    1986. 

Motor   Specifications— QB,    2019. 

Overcompounding— QB.   2023. 

Three-Wire  Generator— QB,   2048. 

Accumulative  vs.  DitTerential  Compounding 
— QB,    2049. 

EjrcHers 

The  Dual  Drive  Units — Ivan  Stewart  Forde. 
Steam  turbine  and  induction  motor  driven  ex- 


THE  ELECTRIC  JOURNAL 


citers.  1-4.  \V-2350.  Vol.  XVIII.  p.  48. 
Feb..    '21. 

Reversal  of  Exciter  Voltage— QB.  1712,  IT:;". 
1746. 

Parallel  Operation  of  Compound  Exciters — 
— QB.  1731. 

Rotary  Converter  as  Self-Excited  Alternator 
— QB.   1856. 

Compound  Versus  Shunt  Exciters— QB.   1905. 

Reversed  Field  Current— QB.  1966. 

SERIES 

Preventing  the  Breakage  of  Armature  Leads 
on  Railway  Motors— A.  L.  Broomall.  I-l. 
W-24S0.      Vol.   XVI,   p.   440,   Oct.,   '19. 

Armature  Trouble  Resulting  from  Broken 
Motor   Leads- ROD,   XVII.  p.   81  ;  231. 

Overloads  in  Railway  Motors— F.  W.  Mc- 
Closkey.     W-2000.     Vol.  XVI.  p.  457.  Oct..  '19. 

Effect  of  Short-Time  Overloads  on  Railway 
Motor  Armatures— J.  K.  Stotz.  C-2.  W-1300. 
Vol.  XVII.  p.  473.  Oct..  '20. 

Some  Mechanical  Causes  of  Flashing  on 
Railwav  Motors— J.  K.  Stotz.  W-1400.  Vol. 
XVIII,    p.    481.    Oct.,    '21. 

Main  Driving  Motors  for  the  Chicago.  Mil- 
waukee &  St.  Paul  Passenger  Locomotives — 
G.  F.  Smith.  T-1.  C-1.  D-1.  1-9,  W-1900.  Vol. 
XVII,   p.   284,  July,  '20. 

Railway  Motor  Testing— ROD.  XVI.  40. 

Testing     Assembled     Railway     Motors — ROD. 

XVI.  168. 

Blasting  Battery— QB.   1707. 
COMMUTATING  POLE 

Testing  Polarity— QB,  1740. 
Operation  at   Low   Voltage— QB.   1979. 
Inductive  Shunt— QB.  2006. 

Alternating  Current 

ALTERNATORS 

Ventilation  and  Temperature  Problems  in 
Large  Turbogenerators — B.  G.  Larame.  1-17. 
VV-7300.  Vol.  XVII.  p.  312.  July;  p.  346. 
AuK..    '20. 

A  Record  of  Large  Turbogenerator  Arma- 
ture Breakdowns— F.  D.  Newbury.  W-1100. 
Vol.   XVII.   p.   353.  Aug.,   '20. 

Embedded  Temperature  Detectors  in  Large 
Generators- F.  D.  Newbury  and  C.  J.  Fech- 
heimer.  T-4,  I-ll.  W-6800.  Vol.  XVII.  p.  410, 
Sept..    '20. 

(E)   B.  A.  Behrend.     W-600.  p.  362. 

Eddv  Current  Losses  and  Temperatures  of 
Stator  Coils  in  Alternating-Current  Generators 
— S.    L.    Henderson.      C-7,    1-7.    W-2460.      Vol. 

XVII.  p.   418.   Sept.,   '20. 

Use  of  Mica  Insulation  for  Alternating- 
Current  Generators— H.  D.  Stephens.  1-7, 
W-2260.     Vol.   XVI,   p.  91,  Mar..   '19. 

A  Vector  Diagram  for  Salient-Pole  Alterna- 
tors—E.    B.    Shand.      D-2.    1-2.    \V-1180.      Vol. 

XVIII.  p.    59.   Feb..   '21. 

Temperature  Indicators  for  Alternators — S. 
L.    Henderson.       C-2.    D-5.    1-4.    W-2300.       Vol. 

XVI.  p.   193.  May.    '19. 

Grounded  Neutral  on  Alternating-Current 
Generators— S.  L.  Henderson.  D-10.  W-2400. 
Vol.   XVI.  p.  340,  Aug..  '19. 

Steam  for  Extinguishing  Fires  in  Turbo- 
Generators  -J.  J.  Dougherty.    1-2.  W-950.    Vol. 

XVII.  p.  202.   May.    '20. 

Mechanical  Construction  of  Water  Wheel 
Driven  Alternators— E.  Mattman.  D-1.  1-13. 
W-2I)00.      Vol.  XVIII.  p.  25.  Jan..  '21. 

Data  and  Tests  on  10000  Cycle  Per  Second 
Alternator— B.  G.  Lamme.  &6.  1-6.  W-25C0. 
Vol.    XVIII.   p.   132.   Apr..   '21. 

The  Main  Generators  of  the  U.  S.  S.  Ten- 
nessee—R.  E.  Oilman.     C-3.  1-5.  W-2040.     Vol. 

XVIII.  p.  284.  June.  '21. 

Effect  of  Connecting  an  Alternator  to  the 
Line  Out  of  Phase— D.  Goodfellow.  I-l.  W-35. 
Vol.  XVIII,  p.  413,  Sept.,  '21. 

Changing  Threc-Phase  to  One-Phase— QB, 
1691. 

Amount  of  Ventilation— QB.  1717. 

Magnetic   Center— QB.    1733. 

Efficiency  of  Water  Wheel  Generator— QB. 
1743. 

Terminal  Insulation— QB.   1767. 

Wave  Form— QB.  1789. 

Reactance  Coils  to  Protect  Coupling— QB. 
1822. 

Compensator  for  Revolving  Armature  Altcr- 
nator— QB.   1828. 

Insulation    of   Field   Coils— QB.    1886. 

Unbalanced   Load— QB.  1890. 

Air-Gaps— QB.    1903. 

Rotor  Design  of  Vertical  Alternator— QB. 
1908. 


Oiling  System   of   Vertical    Units     QB.    1914. 

Eiliciency  of  Water  Wheel  Alternator — QB. 
1918. 

Reconnecting  Threc-Phasc  to  Two-Phase — 
QB.  1960. 

Heating  of  Iron— QB.  1969. 

Damping  Windings— QB.   1977. 

Cutting   Out   Coils— QB.   2002. 

Selecting    Turbogenerator    Units— QB.    2007. 

Heating  of  Stator  Core — QB,  2010. 

Testing  Stator  Coils— QB,  2013. 

Starling  Frequency  Changer  Sets— QB.  2031. 

Unequal  Coil  Grouping — QB.   2054. 

Effect  of  Unbalanced  Load— QB.  2039. 

I'aidllrl  Operation 

Parallel  Operation  of  Gas  Engine  Driven 
Generators— A.  W.  Copley.  T-1,  1-4.  W-1220. 
Vol.   XVII.   p.   385.  Sept..  '20. 

Phasing  Out— QB.   1699. 

Effect  of  Excitation— QB.  1706. 

Division  of  Load— QB,   1770. 

Synchronizing— QB.   1860. 

Parallel  Operation  of  Shaft-Driven  Alterna- 
tors—QB.  1860. 

Eticct  of  Field  Polarity  on  Parallel  Opera- 
tion— QB.   2057. 

SYNCHRONOUS  MOTORS 

The  Relation  of  Flywheel  Effect  to  Hunting 
in  Synchronous  Motors  — Q.  Graham.  C-1. 
W-2300.     Vol.   XVII.  p.   18.  Jan..  '20. 

Principles  and  Characteristics  of  Syn- 
chronous Motors — E.  B.  Shand.  C-4,  1-3, 
W-3400.     Vol.  XVIII.  p.  87.  Mar..   '21. 

Starting  Characteristics  of  Synchronous 
Motors— E.  B.  Shand.  T-1.  C-6.  W-2850.  Vol. 
XVIII.  p.  309.  July,  '21. 

Parallel  Operation— QB.  1701. 

Starting  Trouble— QB.   1760. 

Pull   Out  Torque— QB.   1766. 

Condenser  Operation- QB,   1793. 

Starting— QB.    1794. 

Self  Starting— QB.   1806. 

Self   Starting   Induction    Type— QB.    1847. 

Starting  with  Alternators— QB.   1851. 

For   Power-Factor  Correction— QB.  1859. 

240    and   120    Volt   Excitation— QB.    1887. 


Starting 
Starting 


induction  Motor— QB.  1964. 
•ith     Full     Field     Excitation— QB. 


1996 


rting 


Oper 


m  Half   Voltage— QB.   2021. 
Over  Excited— QB.  2047. 

Relation  of  Excitation  to  Kv-a  -QB.  2051. 

Phasing  Out— QB.  2056. 
INDUCTION    MOTORS 

The  Design  of  Large  Induction  Motors  for 
Steel  Mill  Work— H.  L.  Barnholdt.  C-1.  1-8. 
W-2450.      Vol.  XVI,  p.  251,  June.   '19. 

Interchangcability  of  Squirrel-Cage  Rotors-— 
B.  B.  Ramey  .  T-1.  W-1200.  Vol.  XVI.  p.  481. 
Nov..  '19. 

The  Induction-Typo  Frequency  Changer — 
Harry  S.  Smith.  1-6.  W-1890.  Vol.  XVII,  p. 
342.  Aug..  '20. 

The  Propelling   Motors   of   the   U.   S.  S. 
nessei^-H.      L.      Barnholdt.      T-1. 
W-3820.     Vol.  XVIII.  p.   261,  June.   '21. 

Variable  Speed  Induction  Motor  Sets-  C.  W. 
Kincaid  Kramer.  Scherbius.  freciuency  con- 
verter systems.  D-2.  1-6.  W-3350.  Vol. 
XVIII.  p.   386.  Sept..   '21. 

The  Design  of  Induction  Motors  for  Textile 
Service— O.  C.  Schoenfeld.  1-6.  W-6400.  Vol. 
XVIII.  p.  494.  Nov..  '21. 

Partially  Closed  Slots- QB.  1804. 

Windings 

Reversing  Single  Phase  Rotation  —  EN. 
XVI.   82. 

Secondary  Data-  QB.  1686. 

Secondary  Changes— QB.   1G90. 

Round   vs.  Square  Wires-QB.    1693. 

Coil    Pitch— QB.   1695. 

Number  of  Rotor  Bars— QB.  1715. 

20    H.P.    Rotor    in    a    30    H.P.    Stator     QB. 


D-1.      1-13. 


ni'6 


Short-Circuitcd   Wound  Rotor— QB,   1718. 
Delta   vs.   Star  Connection— QB.  1720. 
Repulsion  Winding-  QB.  1726. 
Reconnecting   Rotor — QB.   1729. 
Grounded  Squirrel  Cage- QB.  1767. 


Rotor  Connections— QB.  1768. 

(hanging  10  Pole  to  6  Pole— QB.  1771. 

Changing  Two-Phase  to  Threc-Phase— QB. 
1771. 

Phase  Splitter— QB.    1780. 

Insulation  of   Squirrel-Cage— QB.   1816. 

Singlc-Phnso   Windings— QB.   1826. 

Motor  Diagrams     IJB,   1861. 

.Mullispeed   .Motor      QB,    1862. 

Open   Delta    Conntctmn— QB,    1895. 

Different  Windings  in  Same  Size  Motor— 
QB,    1899. 

Design  of  Winding  to  Fit  a  Given  Core— 
QB.  1902. 

Overlapping  of   Phase  Groups— QB.   1911. 

Welded  Laminnlions— QB.  1913. 

Pole   Pilch    -QH.    r.i30. 

Unequal    Grouping-  (JB.    1933. 

Changing  to  a  Single-Phase  Generator-  QB. 
1944. 

Grounding  of  Staler  Coils- QB.   1970. 

Chorded   Winding- QB.    1976. 

Threc-Phase    to    Iwo-Phase-  QB.    1982. 

Changing  133  Cycle.  One-Phase  Motor  to  60 
Cycle— QB.    1992. 

Design  of  Rotor  Winding— QB.  2011. 

Drying  Out— QB.  2016 

Effective   Core  Area— QB.   2027. 

Distribution  Factor- QB.  2062. 

Two   Speed   Motor— QB.   2066. 

Special  Insulation  for  Tropical  Countries — 
QB.   2069. 

Short  Circuited  Coil— QB.  2067. 
I'crformaiice 

The  Fifty  Degree  Rise  Method  of  Motor 
Rating— J.  M.  Hippie.  W-2150.  Vol.  XVII.  p. 
203.  May.  '20. 

Thrce-Phasc  Motors  on  One-Phase  Circuits— 
QB.    1696. 

Magnetic  Noise — QB.  1710. 

30  vs.  60  Cycles— QB.   1719. 

Regenerative  Braking — QB.    1721. 

No- Load   Oiieration     QB.   1730. 

With  Open  Secondary     QU,   1766,  1830. 

Horse-Power   Rating     QB.    1779. 

Single-Phase    Rotor    Current— QB.    1788. 

No-I.oad  Current-  QB.   1813. 

Dynamic  Braking     QB.   1846. 

Effect  of  Secondary  Resistance  on  Primary 
Current— QB.   1891. 

Calculating  Starting  Resistance-   QB.  1893. 

Parallel  Operation— QB.   1896. 

Changing  Frequency  of  Line  by  Indurllon 
Motor— QB.   1923. 

Starling  with  Generator — QB.  200ii. 

Secondary  Current  of  Induction  Motor  QB. 
2015. 

Einciency  of  Motor  Rebuilt  After  •  Fire — 
QB.  2017. 

Flash  Over  of  Slip  Ring  Motor     QB.  2022. 

Magnetizing   Current— QB.    2033. 

Starting  Current— QB.  203S. 

Speed  of  25  Cycle  Motor  on  30  Cycles  QB. 
2045. 

Starting  on  eo^i  Voltage— QB.  2064. 

Testing 

Stroboscopic  Slip  Determination  M.  M. 
Bries.  T-1.  1-3,  W-1900.  Vol.  XVII.  p.  105. 
Apr..  '20. 

Reversal  by  Jamming— QB.  1833. 

Low  Torque  Starling  Points — QB.   1835. 

Parallel  Operation— QB.  183:1. 

Performance  Calculations     QB.  1763. 

Apparatus  for  Testing— QB.  1820. 

Determining  Faults— QB.   1S37. 

Temperature   Exploring   Coils     QB.    1845. 

Locating  Trouble— QB.   1849. 

Location  of  Ground— QB.   1897. 

Insulation  Testing  of  Stator— QB,  1915. 

Ammeter   as   Slip    Indicator-  QB.    1939. 

Transformer  for  Testing  Staler- QB.  1994. 
SERIES  MOTORS 

Winding  of   Universal  Motor- QB.   1734. 

Dynamic  Braking  of  a  Single-Phase  Motor — 
QB.    1941. 

FAN  MOTORS 

The  Development   of   Fan   Motor  Windings — 

E.    W.    Penman.     C-1.  D-8.   I-l.   W-2B50.      Vol. 
XVI.    p.    257,   June.    '19. 
D.  C.  on  A.   C— QB.   1700. 


BATTERIES 


A  New  Form  of  Standard  Cell— C.  J.  Rod- 
man and  T.  Spooner.  T-1.  C-1.  1-4.  W-2950. 
Vol.   XVIII.   p.   66.   Feb..   '21. 

Recharging  Dry  Cells— QB.  1832. 


THE  ELECTRIC  JOURNAL 


TRANSFORMATION 


RECTIFIERS 
Mercury  Arc 

Reduction  of  Chargins  Current— QB.  1958. 

Electrolytic 


ROTARY  CONVERTERS 


The  Technical  Story  of  the  Synchronous  Con- 
verter—B.  G.  Lamme.  1-2.  W-14000.  Vol. 
XVII.  p.   55,   Feb.  ;   p.  91.  Mar..   '20. 

Voltage  Regulating  Systems  of  Syn- 
chronous Converters— F.  T.  Haeue.  T-2,  C-2, 
1-2.  W-4000.     Vol.  XVIII,  p.  52.  Feb.,   '21. 

(E)    F.   D.  Newbury.     W-650,   p.  47. 

Determination  of  Stray  Losses  in  60  Cycle 
Synchronous  Booster  Converters  by  Input- 
Output  Tests— F  .T.  Hague.  T-4,  C-5.  1-2, 
W-2450.      Vol.  XVIII,  p.   292,  July,   '21. 

(E)    F.   D.   Newbury.      W-1890.   p.    291. 

Three-Wire  Distribution  from  Rotary  Con- 
verters— L.  Dorfman.  Methods  of  bringing 
out  neutral.  D-3.  W-1100.  Vol.  XVI,  p.  500. 
Nov..   '19. 

Commutator  Maintenance  of  Synchronous 
Converters— OD.  XVIII,  106. 

Fluctuating  Load — QB,  1736. 

Reversing  Direction  of  Six-Phase  Converter 
— QB,    1742. 

Performance  Partly  Loaded — QB,    1764. 

Division  of  Current  in  Booster— QB,  1776. 

Direction   of  Rotation— QB,    1795. 

Windage- QB,  1800. 

Power-Factor   Correction — QB,    1811. 

Starting   Conditions — QB,   1812. 

Operations  on   Open   Delta— QB,   1945. 

Reversed  Rotation — QB,  1965. 


STORAGE  BATTERIES 

Characteristics  of  Starting  and  Lighting  Bat- 
teries of  the  Lead  Acid  Type— O.  W.  A.  Get- 
ting. With  reference  to  low  temperature.  T-2, 
C-14,  I-l,  W-3360.     Vol.  XVI.  p.  134.  Apr.,  'ig. 

(E)   A.  M.  Dudley.     W-610.  p.   112. 

Effect  of  Fluctuating  Current — QB.    1801. 

Effect  of  Freezing — QB.    1838. 

M.  G.  Set  vs.  Rectifier  for  Charging— QB. 
2032. 


TRANSFORMERS 


General 


XVIII— Phase  Transfoi-mation.  D-9,  W-1300. 
Vol.  XVI.  p.  31.  Jan..  '19. 

XIX— Operating  Conditions.  I-l,  W-3030. 
Vol.  XVI.  p.  66.  Feb..  '19. 

XX — Three-Phase  to  Two-Phase  Transforma- 
tion with  Single-Phase  Transformers  Scott 
Connected.  D-7,  W-2000.  Vol.  XVI.  p.  99. 
Mar.,  '19. 

XXI — Voltage  Transformations  with  Auto- 
transformers.  T-1,  C-1,  D-6,  W-1870.  Vol. 
XVI,  p.  145,  Apr..  '19. 

XXII — Phase  Transformation  with  Auto- 
transformers.  C-1.  D-4.  W-1600.  Vol.  XVI.  p. 
216.  May.  '19. 

XXIII— Parallel  Operation.  C-1,  D-2.  W-1500. 
Vol.  XVI.  p.  267.  June,  '19. 

XXIV— Polarity.  D-8,  W-1410.  Vol.  XVI, 
p.   301.  July,   '19. 

XXV— Voltage  Transformers.  T-1.  0-7.  1-6, 
W-4650.     Vol.  XVIII,  p.  323,  July.  '21. 

The  70,800  Kv-a  Transformer  Bank  of  the 
Colfax  Generating  Station  of  the  Duquesne 
Light  Company — M.  E.  Skinner.  T-1,  D-2, 
I-IO,  W-2200.     Vol.  XVIII,  p.  229,  May,  '21. 

The  Insulation  of  Distribution  Transformers 
—A.  C.  Farmer.  1-15,  W-3000.  Vol.  XVI,  p. 
223,  May,   '19. 

Transformers  and  Connections  to  Electric 
Furnaces — J.  F.  Peters.  C-2,  D-1,  1-4, 
W-1250.     Vol.  XVI,  p.  397,  Sept..  '19. 


Transformer  Equipment  for  the  Chicago, 
Milwaukee  &  St.  Paul  Locomotives— W.  M. 
Dann.     1-6.  W-1350.     Vol.  XVII,  p.  9.  Jan.,  '20. 

Steel  Clad  Distribution  Transformers— E.  G. 
Reed.  1-22,  W-1900.  Vol.  XVII,  p.  213, 
May,  '20. 

Static  Frequency  Doublcrs — J.  F.  Peters. 
C-2,  1-2,  W-1100.  Vol.  XVIII,  p.  122, 
Apr.,    '21. 

Experience  in  Drying  Out  Large  Transform- 
ers— S.  H.  Abbott.  I-l,  W-950.  Vol.  XVIII, 
p.  92,  Mar.,  '21. 

Transformers  for  Synchronous  Converters — 
OD,   XVIII,  618. 

For  Testing  Armature  Short-Circuits- QB, 
1705. 

High  Voltage  Transformers  for  Crookes 
Tubes— QB,    1732. 

Draining  Water  Cooled— QB,  1853. 

Noise  Due  to  Charging  Arresters— QB,  1888. 

Secondary   Equivalent    Resistance — QB,   2040. 

Cleaning   Water   Coils— QB,   2043. 

Windings 

Tertiary    Windings    in    Transformers — J.    F. 

Peters.  Their  effect  on  short-circuit  currents. 
T-1,  C-3,  D-5,  W-2800.  Vol.  XVI,  p.  477. 
Nov.,    '19. 

Changing  Frequency — QB,   1688. 

Testing  for  Reversed  Coil— QB,  1987. 

Rewinding  Small  Transformers— QB,  2034. 


Connections 

Grounding  Delta— QB,    1692. 

Connections  for  Various  Voltages— QB,  1689. 

Reversing  Direction  of  Six-Phase  Converter 
— QB,    1742. 

Star  and  Delta  Voltages— QB,   1747. 

Unsymmetrical    Delta— QB,    1773. 

Half  Voltage  Taps  on  Delta— QB,  1829,  1948, 
1980,    2071. 

Booster- QB,  1783. 

Interconnected  Star — QB,  1817. 

Reversed  Phase  in  Delta— QB,  1875. 

Three-phase   Booster— QB,    2050. 

Delta  Transformers  Connected  Star — QB, 
2063. 

POLYPHASE  TO  ONE-PHASE 

One-Phase  from  Threc-Phasc  for  Welding— 
QB,  1937. 

THREE-PHASE  TO  TWO-PHASE 

The  Development  of  the  Two-Phase,  Three- 
Phase  Transformation — Chas.  F.  Scott.  D-6, 
W-2400  .  Vol.  XVI.  p.   28.  Jan..  '19. 

Phase  Transformation— E.  G.  Reed.  D-9, 
W-1300.     Vol.    XVI.  p.    31,   Jan..   '19. 

Three-Phase  to  Two-Phase  Transformation 
with  Single-Phase  Transformers  Scott  Con- 
nectcd— E.  G.  Rccd.  D-7.  W-2000.  Vol.  XVI, 
p.    96,    Mar.,    '19. 

Three-Phase  to  Two-Phase  Transformation — 
J.  B.  Gibbs.  T-2,  D-17,  W-2220.  Vol.  XVI.  p. 
103,  Mar.,   '19. 

(E)    Chas.  R.  Riker.     W-S70.  p.  83. 

Phase  Transformation  with  Autotrans- 
formers— E.  G.  Reed.  C-1,  D-4,  W-1600.  Vol. 
XVI,  p.  216,  May.  '19. 

Three-Phase  to  Two-Phase  Three-Wire  Trans- 
formation with  Autotransformers — E.  P.  Wim- 
mer.  T-1,  C-1,  D-6.  W-1300.  Vol.  XVIII,  p. 
15,  Jan.,  '21. 

Phase  Transformation- QB,  1741,   1988. 

Calculation  of  Currents  with  Unsymmetrical 
Loads— QB,   1864. 

Poor  Regulation— QB,  1870. 

Metering  Load  on  Secondary  of  Taylor  Con- 
nections— QB,   1952. 

OPEN  DELTA 

Motor  Capacity  of  Open  Delta  Connection — 
QB.   1904. 

Open  Delta— QB.  1827. 

PARALLEL 

Parallel    Operation    of    Transformers — E.    G. 

Reed.      C-1.    D-2.    W-1500.      Vol.    XVI,    p.    267. 
June.    '19. 

Paralleling  Transformers — QB,   1946,  2001. 


Transformer    Polarity— E.     G.     Reed.        D-S. 
W-1410.      Vol.   XVI,    p.   301.   July,    '19. 


Performance 

Changing   Frequency — QB,    1688,   1926. 
Phase  Relations— QB,   1753. 
Switching    Loaded    Transformers— QB,    1756, 
955. 
Effect  of  Harmonics — QB,    1907. 
Charging  Current— QB,   1931. 
Operating  60  Cycle  on  50  Cycle— QB,  2036. 


Testing 

Safety-First  Testing  of  Small   Transformers 

—A.  Heckman.  D-2.  1-2.  W-1700.  Vol.  XVII. 
p.   338.   Aug.,   '20. 

(E)    Chas.   R.   Riker.      W-350,   p.   319. 

Testing  Transformer — QB,  1898. 

Transformer  for  Testing  Induction  Motor 
Stators— QB.    1994. 

Transformer  for  Testing  Dielectric— QB. 
2073. 


Instrument 

The  Choice  of  Instrument  Transformers — L. 
Dorfman.  W-1050.  Vol.  XVII.  p.  341. 
Aug.,  '20. 

Grounding — QB.   1868. 

SERIES 

(For   Connections,   sec   also   "Meters") 

For   Constant   Current   Systems- QB.    1796. 

Measuring  Three-Phase  Current  with  Two 
Transformers     QB.   1C98.    1978. 

Connections  for  Tirrill  Regulator— QB.  1818. 

Reversed  Power  Relay  Connections — QB. 
1824. 

Split    Core    Type— QB.    1872.    1876. 

Inverted- QB.  1884. 

Meter  Connections- QB.   1934. 

Operation  in  Scries- QB.  2004. 

Cross  Connections— QB.   205S. 

Z  Connection-  QB.   2063. 

POTENTIAL 

Voltage  Transformers — E.  G.  Reed.  T-1. 
C-7.  1-6,  W-46o0.     Vol.  XVIII,  p.  323.  July.  '21. 


Autotransformers 

(See    also    Three-Phase   to    Two-Phase    Trans- 
formers) 

Voltage  Transformations  with  Autotrans- 
formers—E.  G.  Reed.  T-1,  G-1.  D-6,  W-1870. 
Vol.  XVI.  p.   145.  Apr..  '19. 

Scott  Connection— QB,  1702. 


Thr 


Reactance  Coils 

>-Phase   Current    Limiting   Reactors — M. 

1-8.   W-1650.     Vol.   XVIII,  p.   23, 


E.   Skin 
Jan.,   '21. 

Current  Limiting  Reactors  Commonly  Pro- 
tect both  Service  and  Equipment— K.  G.  Ran- 
dall.    Vol.  XVII,  p.   248,  June,  '20. 

To  Protect  Turbo-Generator  Coupling — 
QB.  1822. 

Rating  of— QB,   1910. 


Oil 

Some  Characteristics  of  Transformer  Oils — 
O.  H.  Eschholz.  T-1,  C-1,  I-l,  W-1800.  Vol. 
XVI,  p.  74,  Feb.,  '19. 


CONDENSERS 


THE  ELECTRIC  JOURNAL 


TRANSMISSION 

CONDUCTORS    and    CONTROL 


GENERAL 

(See  also  Theory,   p.  5) 

Electrical  Characteristics  of  Transmission 
Circuits — Wni.  Nesbit. 

I— Resistance— Inductance.  T-5.  C-1.  1-5. 
W-5000.     Vol.  XVI.  p.  279,  July.  '19. 

(E)    Chas.    F.   Scott.      W-1000,   p.   275. 

II— Reactance.  T-9.  C-2,  D-2.  W-3300.  Vol. 
XVI.  p.   314.   Aut'..  '19. 

Ill— Quick  Estimatine  Tables.  T-10.  C-1. 
W-1700.      Vol.  XVI,   p.   385,  Sept.,   '19. 

IV— Corona  Effect.  T-3.  W-2900.  Vol  XVI, 
p.  485.  Nov.,  '19. 

V — Electric  Propaeation— Paralleling— Heat- 
ing of  Conductors.    T-1,  C-1,  I-l,  W-3000.    Vol. 

XVI.  p.  616,  Dec,   '19. 

VI — Frequency  and  Voltage  Determinations. 
T-4.  W-3050.     Vol.  XVII,  p.  21.  Jan.,   '20. 

VII — Performance  of  Short  Transmission 
Lines  (Capacitance  not  Taken  into  Account). 
T-3.  D-2,  I-l,  W-800U.  Vol.  XVII,  p.  66, 
Feb..  '20. 

VIII — Graphical  Solution  of  Long  Lines. 
T-1,  C-4,  D-U,  I-l,  W-7000.  Vol.  XVII,  p. 
104,  Mar.,  '20. 

(E)    Chas.  R.   Riker.      W-1000,   p.  83. 

IX — Convergent  Series  Solution  of  Long 
Lines.  T-6.  D-9.  W-6700.  Vol.  XVII,  p.  14B. 
Apr.,  '20. 

X — Review  of  Hyperbolic  Trigonometry.  C-2. 
D-9.  W-4000.     Vol.  XVII,  p.  267,  June,  '20. 

XI — Solution  of  Long  Lines  by  Hyperbolic 
Functions.  T-2.  D-1,  1-9,  W-5460.  Vol.  XVII, 
p.    299.    July,    '20. 

(E)    Chas.   R.   Riker.      W-210.  p.  277. 

XII  and  XIII — Comparison  of  Methods  of 
Solving  Long   Lines.     T-2,  D-4.   W-6000.      Vol. 

XVII.  p.   360,   Aug.:   p.   627.   Nov.,    '20. 
XIV— Heating   Limits  tor  Cables.      T-5,   C-1, 

1-2.   W-2900.      Vol.   XVII,  p.  675.  Dec,   '20. 

XV — Synchronous  Motors  and  Condensers  for 
Power-Factor  Improvement.  T-4,  C-3,  1-3, 
W-5730.      Vol.  XVIII,  p.   366,  Aug.,   '21. 

XVI— Phase  Modifiers  for  Voltage  Control. 
T-2.  D-1.  W-3350.     Vol.  XVIII.p.  542.  Dec.  '21. 

Transmission  Line  Circuit  Constants  and 
Resonance — R.  D.  Evans  and  H.  K.  Sels.  T-4. 
C-2.  1-4,  W-2250.    Vol.  XVIII,  p.  306.  July,  '21. 

(E)    F.  C.  Hanker.     W-400,  p.   291. 

Transmission  Line  and  Transformers  R.  D. 
Evans  and  H.  K.  Sels      T-4,  1-2.  W-1900.     Vol. 

XVIII.  p.   365.   Aug..  '21. 

Circle  Diagrams  for  Transmission  Systems — 
R.  D.  Evans  and  H.  K.  Sels.  T-1,  Ol,  D-6. 
W-5060.     Vol.  XVIII.  p.  530.  Dec.  '21. 

Testing  for  Short-Circuit  Currents  in  Net- 
works— W.  R.  Woodward.  With  Miniature 
Net-works.  D-1,  1-2,  W-1280.  Vol.  XVI,  p. 
344,  Aug.,  '19. 

(E)   A.   W.   Copley.     W-800.   p.  314. 

Analytical  Solution  of  Short-Circuit  Currents 
in  Networks— Robert  D.  Evans.  D-21,  W-3100. 
Vol.   XVI.   p.  345.  Aug..   '19. 

Development  of  Analytical  Solutions  in  Net- 
works--Chas.  Fortescue.  W-2800.  Vol.  XVI. 
p.  350.  Aug..  '19. 

Substation  Short-Circuits — R.  F.  Gooding. 
T-6.  D-6.  W-3030  .  Vol.  XVI.  p.  61.  Feb.,  '19. 

Electrical  Transmission  vs.  Coal  Transporta- 
tion—Harold W.  Smith.  T-4,  C-3,  W-1780.  Vol. 
XVIII,  p.  402,  Sept.,  '21.  ~ 

Short-Circuit    Calculations— QB.    1786. 

Capacitance  Measurements — QB,  1823. 

Performance  of  Transmission  Line,  Interfer- 
ence—QB,   2018. 

Power-Factor 

Power-Factor      in      Polyphase      Circuits — A. 

Nyman.  D-3,  W-2400.  Vol.  XVIII,  p.  20, 
Jan.,   '21. 

Power-Factor  Correction  in  Siecl  Mills — 
Hollis  K.  Sels.  T-2,  C-4,  1-3,  W-2860.  Vol. 
XVIII,  p.  419.  Sept.,  '21. 

Average  Power-Factor — QB,  1852. 

Synchronous  Motors  for  Power-Factor  Cor- 
rection—QB.   1859. 

Transmission  Power-Factor— QB.  1906. 

SYSTEMS 

The  Electric  Power  Supply  for  the  Puget 
Sound  Lines  of  the  Chicago,  Milwaukee  &  St. 
Paul  Railroad— A.  W.  Copley.  D-4,  1-12, 
W-1950.     Vol.  XVII,  p.  3.  Jan.,  '20. 

Switching  and  Protection  of  Transmission 
Circuits— S.  Q.  Hayes.  C-1,  D-9,  1-66,  W-17500 
Vol.  XVII,  p.  178,  May;  p.  263.  June:  p.  621, 
Nov. :  p.  655,  Dec,  '20. 

Interconnection  of  Power  Systems — Harold 
W.  Smith.  1-6,  W-3060.  Vol.  XVII,  p.  515, 
Nov.,  '20. 


The  Transmission  System  of  the  West  Penn 
Power  Company — Geo.  S.  Humphrey.  1-6. 
W-4280.     Vol.  XVIII,  p.   169,  May,  '21. 

(E)    A.  H.  Mclntire.     W-1750,  p.   166. 

The  Transmission  Ring  of  the  Duqucsne 
Light  Company — E.  C.  Stone.  C-l,  D-7,  1-7. 
W-4750.     Vol.  XVIII.  p.  211,  May,  '21. 

(E)   C.  S.   Cook.     W-COO.   p.   166. 

The  Power  System  of  the  U.  S.  Steel  Cor- 
poration in  Pittsburgh — S.  S.  Wales.  I-l. 
W-980.     Vol.  XVIII,  p.  222.  May.  '21. 

Kcgulation  and  Inductive  Effects  in  Single- 
Phase  Railway  Circuits— A.  W.  Copley.  T-l, 
C-1.  D-23.  W-10650.  Vol.  -XVII.  p.  326. 
Aug..  '20. 

Three-Phasc,  Four-Wire  Distribution— Geo. 
E.    Wagner.      D-7,   W-3350.     Vol.    XVI,   p.    99. 


Mai 


'19. 


Monocyclic-  QB.   1697. 

Voltage  Between  Phases — QB,  1714. 

Arrangement  of  Cables  in  Conduit — QB. 
HI25.   1927. 

Three-Wire  vs.  Four-Wire,  Two-Phase  Dis- 
tribution—QB.  1935. 


LINES 

Nicholson  Arc  Suppressor — QB.  1956. 

Underground 

Allowable  Working  Stresses  in  High-Voltage 
Electric  Cables— Chas.  W.  Davis  and  Donald 
M.  Simons.  T-1,  C-2,  W-5400.  Vol.  XVII,  p. 
292.  July,   '20. 

Heating  Limits  for  Cables — Wm.  Nesbit. 
T-5,  C-1,  1-2,  W-2900.  Vol.  XVII,  p.  675. 
Dec.  '20. 

Disposition  of  Conductors— QB,  1694. 

Cahle  Insulation- QB.   1784. 

Choke  Coil  Effect  of  Armored  Cable— QB. 
1967. 

Overhead 

Farm  Line  Business  at  a  Profit  to  the  Cen- 
tral Station— H.  W.  Young.  I-l,  W-1350.  Vol. 
XVII.    p.    79.    Feb.,    '20. 

Renewal  of  the  Catenary  Construction  in  the 
Hoosac  Tunnel— L.  C.  Winship.  1-4,  W-2760. 
Vol.  XVIII.   p.   84.  Mar..  '21. 

Transposition   of   Conductors— QB.    1723. 

Conductor  Insulation— QB.  1781. 

Spacing  of  Poles— QB,  1880. 

Transmission   Power-Factor- QB,    1906. 

Equivalent  Spacing— QB.   1989. 

Division  of  Current  in  Parallel  Conductori 
— QB.  2070. 

GROUNDING 

Resistance  of  Ground  Connections — EN. 
XVI,  157. 

Arcing  Ground     QB.  1831. 

Grounding  Delta— QB.    1692. 

Grounding  Coal   Rig— QB.  1792. 

Grounding  High  Tension   Lines     QB.   1871. 

Position  of  Overhead  Ground  Wire— QB. 
1865. 

Static    Wires   of   Transmission    Circuits— QB. 

Effect   of  Ground— QB.    1961. 

Conductors 

The  Electrical  Characteristics  of  Transmis- 
sion Conductors  with  Steel  Cores— H.  B. 
Dwight.  T-1,  l-l,  W-1200.  Vol.  XVIII,  p.  9. 
Jan..  '21. 

Resistance  and  Reactance  of  Commercial 
Steel  Conductors— H.  B.  Dwight.  T-1.  C-16, 
W-980.     Vol.  XVI.  p.  26.  Jan.,  '19. 

Steel  Conductors — QB.   1953. 

Reactance  Values  for  Rectangular  Conduc- 
tors—H.  B.  Dwight.  C-1,  I-l,  W-1200.  Vol. 
.WI.   p.    255.   June,   '19. 

Heavy  Alternating-Current  Conductors — EN. 
XVI.   343. 

Carrying  Capacity  of  Iron  Pipes — QB.   1711. 

Capacity  of  Copper  Wires— QB,  1713. 

Fusing  Current  -QB,  1759. 

Conductor  Having  a  High  Negative  Coeffi- 
cient of  Resistance— QB.   1959. 

Heating  of  Iron  Surrounding  a  Conductor — 
QH.    2000. 

Soldered  Joint— QB.  2020. 

SWITCHBOARDS 
General 

Switchboard  Meter  Connections  for  Alter- 
nating-Current Circuits — J.  C.  Group.  Sec 
"Meters." 


InHtallation  of  Switchinf  Equipment  for 
Synchronous  (inverter  Substations  OD. 
XVlll.   329. 

Division  of   Load   in    lling  Bus— QB,   1869. 

Generator    Wiring     Ql!.    1H>.5. 

Hus-Bar    ArrnnKtinenl      QH,    1920. 

Eleclroilalic   Ground    Dcleclor- QB.   1940. 

Switching   Lariic   Traniformcrs— <QB,    1965. 

Potentiometer   Leads— QB,   1999. 

Interrupting  Devices 


European  Iligh-Vollage  Swilchgear  W.  A. 
Coates.  1-13.  W-3730.  Vol.  XVI,  d.  243. 
June.  '19. 

(E)    (has.  R.   Riker.     W-660.   p.   234. 

Large  Capacity  Circuit  Breakers— H.  G. 
MacDonnld.  1-2,  W-1320.  Vol.  XVI.  n.  261, 
June.   '19. 

Inverted  Contact  Circuit  Breakers — II.  G. 
MacDonald.  1-3.  W-800.  Vol.  -Wll.  p.  78. 
Feb..   '20. 

Oil  Circuit-Breaker  Arrangements  and 
Switching  Schemes  for  Steel  MiUi  G.  P. 
Wilson.  Ol.  D.14,  W-6250.  Vol.  XVII.  n. 
402.   Sept..    '20. 

High-Speed  Air-Brake  Circuit  Breakers- G. 
G.  Grissingor.  C-1,  1-3.  W-1200.  Vol.  XVIII. 
p.   69.    Feb.,    "21. 

The  Control  Room  Circuit  Breaker  Equip- 
ment of  the  U.  S.  S.  Tennessee  E.  K.  Read. 
I-IO.   W-3200.      V..1.    XVIII.   p.   258.  June.    '21. 

Short-Circuit   Calculations — QB.    17S6. 

Calculation  of  Circuit  Breaker  Capacity- 
QB.    1917. 

Air  Break  Types— QB.  1936. 

Selection   of— QB.    1942. 

Current  Rating     QB.   1990. 


FUSES 

Maintenance  of  Fuse  Boxes  for  Kail*  ay 
Service     ROD.   XVI.   p.   399. 

Current  to  Fuse  Heavy  Copper  Wire  QB. 
1769. 

Expulsion  Fuses — QB.  1790. 

Temperature  Indicator— QB,   1867. 

(kneralor   Fuses     QB,  1883. 

Carbon-Tetrachloridc — QB,  2008. 

Protective 

Impulse-Gap  Lightning  Arresters— Q.  A. 
Brackctt.  C-1.  D-1.  1-2.  W-1690.  Vol.  XVI. 
p.    52.    Feb..   '19. 

Lightning  Arresters  to  Absorb  Indaetive 
Kick— QB.    1772. 

Choke  Coils-  QB.   1809. 

Lightning    Protection   for    Meters— QB.    1825. 

Testing  Electrolyte  for  Impurities— QB.  1836. 

Noise  in  Transformers  Due  to  Charging— 
QB.   1888. 


Choke   Coil— QB.   1976. 

Lightning    Arrester    Connections — 2075. 

Synchronizing  Schemes 

Synchronizing  with  Lamps — J.  C.  Group. 
D.2.  1-4.  W-185II.      Vol.  XVII.  p.  536.  Nov.,  "20. 

Synchronizing  with  Synchronoscopea — J.  C. 
Group.  D-13.  W-26.-,0.  Vol.  XVII.  p.  667, 
Dec,   '20. 

Synchronizing   Alternators — QB.    1850. 

Synchronizing  Two-Phase  to  Three-Phase 
Lines— QB,   1951. 


RKGUL.\TION   AND   CONTROL 
Regulators 

The  Step  Induction  Regulator— E.  E.  Lchr. 
C-1,  D.4,  1-7,  W-2600.  Vol.  XVII.  p.  610. 
Nov..  '20. 

Tie  Line  Application  for  Induction  Feeder 
Regulators— C.  R.  Gilchi-est.  D-1.  1-6,  W-1000. 
Vol.   XVII.  p.   518.  Nov.,    20. 

The  Liquid  Slip  Regulator—Guy  F.  Scott. 
C-2.  1-3.   W-1250.     Vol.  XVIII.  p.  87.  Jan..  '21. 

Transformer  Connection.s— QB,  1703. 

Connection  of  Tirrill  Regulator- QB.  1818. 

Induction    Regulator-    QB.   1840. 


THE  ELECTRIC  JOURNAL 


Controllers 

INDUSTRIAL 

Improvements  in  Contactor  Types  of  Indus- 
trial Controllers— H.  D.  James.  C-2,  D-2,  1-8. 
W-2600.      Vol.    XVI,  p.    489.   Nov..    '19. 

Manual  Starters  for  Small  Squirrel-Cage  In- 
duction Motors — C.  K.  Applegarth  and  H.  D. 
James.  C-3.  1-9.  W-1850.  Vol.  XVI.  p.  632. 
Dec.   '19. 

(E)   J.  M.  Curtin.     W-350.  p.  607. 

Autotransformer  Motor  Starters  —  H.  D. 
James  and  R.  E.  DeCamp.  T-2.  C-1.  D-7.  1-3. 
W-35C0.     Vol.   XVII.  p.  30.  Jan..   '20. 

Current  Limit  Acceleration  for  Electric 
Motors— H.  D.  James.  C-1.  D-4.  1-3.  W-2350. 
Vol.   XVII.  p.   51.  Feb..  '20. 

Starting  Compensator— Q.  B,  1799. 

Specific  Aptt'caiions 

Direct-Current  CKANE  Controllers— H.  D. 
James.  C-1.  D-1.  1-9.  W-2820.  Vol.  XVII,  p. 
380.  Sept..  '20. 

ELEVATOR  Operation— QB.  1843. 

Electric  Controllers  for  Mine  HOISTS— W. 
C.  Goodwin.  D-1.  1-6.  W-2200.  Vol.  XVII.  p. 
119.  March,  '20. 

The  Control  Equipment  of  the  Propelling 
Machinery  of  the  U.  S.  S.  Tennessee — M.  Cor- 


nelius,    D-1.  1-4,  W-6600.     Vol.  XVIII,  p.   263, 
June,  '21. 

The  Control  of  the  Secondaries  of  the  Main 
Propulsion  Motors  of  the  U.  S.  S.  Tennessee— 
W.  C.  Goodwin.  1-3,  W-1300.  Vol.  XVIII,  p. 
278,   June,    '21. 

RAILWAY 

Automatic  HL  Control  for  Boston  Surface 
Cars— A.  D.  Webster.  T-1,  D-1,  1-9,  W-3600. 
Vol.  XVI,  p.  459,  Oct.,  '19. 

Testing  Railway  Control  Equipment — W.  H. 
Ponsonby.  D-2,  1-6,  W-2100.  Vol.  XVI,  p.  87, 
Mar.,    '19. 

Maintenance  of  Magnet  Valves — ROD,  XVI, 
p.    353. 

Lubrication     of     Control     Apparatus — ROD, 

XVI.  p.    468. 

The  Electrical  Equipment  and  Control  of  the 
Chicago,  Milwaukee  &  St.  Paul  Locomotives — 
P.  L.  Mardis.  T-1.  D-4,  1-14,  W-5000.  Vol. 
XVir,   p.  235,  June,   '20. 

The  Auxiliary  and  Lighting  Control  Equip- 
ment of  the  Chicago,  Milwaukee  &  St.  Paul 
Locomotives — John  A.  CInrKe.  Jr.  D-2,  1-8, 
W-2500.      Vol.   XVII.   p.    244.   June.   '20. 

Methods  of  Protecting  Electrical  Equip- 
ments—Lynn   G.    Riley.       1-12,    W-1800.      Vol. 

XVII,  p.  453,   Oct.,   '20. 


Multiple-Unit      Train      Operation — S.      B. 

Schenck.  D-1,  1-6,  W-2300.  Vol.  XVII,  p. 
457.  Oct.,  '20. 

Multiple-Unit  Control  Equipments  for  th« 
Cleveland  Interurban  Railway  Company — H.  R. 
Meyer.  D-2,  1-12,  W-3000.  Vol.  XVII.  p.  464, 
Oct.,    '20. 

Foot  Control  of  Safety  Cars  as  Exemplified 
by  the  Third  Avenue  Safety  Cars  in  New  York 
— B.  O.  Austin.  D-1,  1-5,  W-1700.  Vol.  XVII, 
p.    488,    Oct.,    '20. 

Voltage  'Testing  of  Control  Equipment — 
ROD.   XVII,  p.  318. 

Types  of  Transition  Used  to  Obtain  Series — 
Parallel   Operation — ROD,  XVIII,   46. 


Rheostats 

The  New  Liquid  Rheostats  for  the  Norfolk 
&  Western  Railway— D.  C.  West.  1-1,  W-1600. 
Vol.   XVII.  p.  483.  Oct.,  '20. 

Adjustable  Laboratory  Rheostats — Thomas 
Spooner.  T-1,  1-6.  W-1470.  Vol.  XVIII.  p. 
57.  Feb..  '21. 

Mounting  and  Maintenance  of  Car  Resistors 
—ROD.   XVI.  269. 

Grid  Resistance  Design— ROD.  XVIII.  556. 

Calculating  Starting  Resistance  for  Induc- 
tion Motors — QB.  1893. 


GENERAL 

Merchandising     Electrical     Appliances — Wm. 

T.  Reace.  1-2.  W-1450.  Vol.  XVII.  p.  229. 
May.   '20. 

Appliance  Outlets— Chas.  R.  Riker.  (E) 
W-210.     Vol.  XVII,  p.  277,  July,  '20. 

Diversity  Factor— QB,  1964. 


ELECTROCHEMISTRY 

Developing  Our  Electrochemical    Resources — 

C.  G.  Schluederberg.  (E)  W-2300.  Vol.  XVI. 
p.  3.  Jan..  '19. 

Electric  Furnaces  for  Steel  Foundries — W. 
E.  Moore.  With  Historical  Introduction.  T-3. 
1-3.  W-4760.     Vol.  XVI.  p.  360.  Sept..  '19. 

Electric  Furnaces  for  Refining  Steel— QB. 
2060. 

The  Manufacture  of  Ferro-AUoys  in  Electric 
Furnaces— C.  B.  Gibson.     T-1.  1-3.  W-6500.  Vol. 

XVI,  p.   366.   Sept..   '19. 

Electric  Brass  Meltine- Its  Process  and 
Present  Importance— H.  M.  St.  John.  W-8000. 
Vol.  XVI.  p.  373.  Sept..  '19. 

Transformers  and  Connections  to  Electric 
Furnaces— J.  F.  Peters.  C-2.  D-1.  1-4.  W-1250. 
Vol.  XVI.  p.  397.  Sept..  '19. 

The  Electric  Furnace  as  a  Central  Station 
Load  with  Particular  Reference  to  Phase- 
Balancing  Systems— R.  D.  Evans.  D-17.  1-2. 
W-5200.     Vol.   XVII.   p.  373,   Sept.,  '20. 

(E)  C.  B.  Gibson.     W-640.  p.  361. 

Automatic  Regulation  of  Electric  Arc  Fur- 
naces—G.  Y.  Allen.  C-2,  D-4,  1-4,  W-3500. 
Vol.  XVII,  p.  397,  Sept.,   '20. 

Secondary  Conductors  for  Electric  Furnaces 
—Edward  T.   Moore.     D-1,   I-ll.   W-2380.     Vol. 

XVII.  p.  422.  Sept..  '20. 

Electric  Furnace  Gray  Iron — Jas.  L.  Caw- 
thon.  Jr.  1-4.  W-2950.  Vol.  XVIII.  p.  396, 
Sept.,  '21. 

Manufacture  of  Oxygen— QB,  1728. 

Electrolysis— QB,   1765. 

Electrolytic  Corrosion— QB,   1854. 

Electric    Furnace   tor   Glass  Mfg.— QB,    1802. 

Photo  Electric  CeU— QB,  1995. 

LIGHTING 

Lighting  without  Hanging  Ceiling  Fixtures — 

J.  L.  Stair.  Indirect,  cove,  column  and  wall 
boxes  and  pedestal  lighting.  1-14,  W-2860. 
Vol.  XVI,  p.  183,  May,  '19. 

Improved  Industrial  Lighting  —  Wm.  T. 
Reace.  I-l.  W-1000.  Vol.  XVI.  p.  197. 
May.  '19. 

Notes  on  Industrial  Lighting — Otis  L.  John- 
son. C-3.  1-6.  W-2360.  Vol.  XVII.  p.  198. 
May.  '20. 

Increasing  the  Load  with  Portable  Lamps — 
Arthur  E.  Frankenberg.  W-llDO.  Vol.  XVI, 
p.  215,  May,   '19. 

Day  and  Night  Lighting  in  Textile  Mills — 
S.  G.  Hibben.  C-2.  1-5,  W-1T50.  Vol.  XVIII, 
p.   615,  Nov.,   '21. 

Ornament  Street  Lighting — L.  A.  S.  Wood. 
I-IO,  W-1350.     Vol.  XVU.  p.  195.  May.  '20. 

Chemistry  and  Chemical  Control  in  the 
Lamp  Industry — Albert  Brann  and  A.  M. 
Hageman.  I-l.  W-3100.  Vol.  XVI.  p.  198. 
May.  '19. 


UTILIZATION 

Mazda  C  Lamps  for  Motion  Picture  Projec- 
tion—A.  R.  Dennington.  D-1.  1-5.  W-2420. 
Vol.  XVI.  p.   201.  May.  '19. 

Lamp   Resistance — QB.    1842. 

Cementing  Base  of  Incandescent  Lamp — QB, 


Violet  Ray— QB.   2014. 
Microlarabert— QB.  2039. 


POWER 
General 

The  Industrial  Field  of  the  West  Pcnn 
Power  Company— G.  H.  Gadsby.  W-3700.  Vol. 
XVIII,  p.  219.  May.   '21. 

Power  Requirements  in  the  Pittsburgh  Dis- 
trict—Joseph McKinley.  C-1,  1-3,  W-2500.  Vol. 
XVIII,   p.   219.  M^iv.    '21. 

(E)    A.  H.  Mclntire.     W-1760,   p.   165. 

Motors  and  Their  Application 

(See   also    "Controllers") 
Protection  from  Dirl — QB,   1687. 
Motors  in  Parallel— QB,   1896. 
Advantages  of  Electric  Drive — QB,  1949. 
Diversity  Factor— QB.   1964. 

SPECIFIC  APPLICATIONS 

(Arranged    Alphabetically) 

Electrically  Operated  Grain  CAR  UN- 
LOADERS— R.  T.  Kintzing.  1-7,  W-1860.  Vol. 
XVIII,  p.  301,  July.  '21. 

Direct-Current  Motors  for  CRANE  and 
Hoist  Work— F.  L.  Moon.  C-4,  1-3.  W-2370. 
Vol.   XVII.   p.  532.  Nov..  '20. 

(E)  L.  C.  McClurc.     W-300.  p.  601. 

Electric  DREDGING  on  the  Yukon — Allen  E. 
Ransom.  T-3,  1-13.  W-1800.  Vol.  XVII.  p. 
86.  March.  '20. 

Automatic  Push  Button  ELEVATORS— H. 
L.  Keith.  1-5,  W-1500.  Vol.  XVI,  p.  512, 
Dec,   '19. 

ELEVATOR  Load— QB,  1736. 

ELEVATOR  Operation— QB,   1843. 

EXCAVATING  with  Electric  Power  in  the 
Miami  Conservancy  District — L.  C.  McLure. 
T-1,  1-2,  W-1050.  Vol.  XVIII,  p.  359, 
Aug.,  '21. 

HOIST  Motor— QB,   1708. 

Induction  Motor  Drive  for  Skip  HOIST— F. 
R.  Burt.  C-2,  D-1,  I-l,  W-1260.  Vol.  XVI,  p. 
381,    Sept.,   "19. 

Electricity  in  the  HOTEL  Pennsylvania— W. 
H.  Easton.  T-1.  1-18.  W-3220.  Vol.  XVI,  p. 
288,  July,   '19. 

The  IRRIGATION  of  the  Desert— E.  B. 
Criddle.  1-2.  W-ISOO.  Vol.  XVII.  p.  193. 
May,  '20. 

Electricity  in  METALLURGICAL  Processes 
—Robert  M.  Kcency.  T-3,  W-6250.  Vol. 
XVII,  p.  206,  May,  '20. 

Electricity  in  MOTION  PICTURE  Studios— 
H.  F.  O'Brien.  1-5.  W-1500.  Vol.  XVII.  p. 
223,  May,  '20. 

Portable  Electrical  Equipment  for  MOTION 
PICTURE  Photography— J.  A.  White.  1-5. 
W-1260.     Vol.  XVIII,   p.  71,  Feb.,   '21. 


Automatic  Speed  Control  for  Sectional 
PAPER  MACHINE  Drive— Stephen  A.  Staegc. 
1-5.    W-29no.      \ol.   XVIII.   p.   78,  Mar.,   '21. 

I  El   W.  H.  Artz.     W-750,  p.  77. 

Some  Features  of  the  Cottrell  PRECIPITA- 
TOR Plant  at  the  Hayden  Smelter  C.  G. 
Hcrshcy.  1-7,  W-1080.  Vol.  XVIII.  p.  304. 
July.   '21. 

Centrifugal  PUMPS -QB.  1819. 

Speed    of    Motor    Driven    PUMPS— QB.    1877. 

Electrical  REFRIGERATION— C.  J.  Carlson. 
T-2.  1-7,  W-2200.      Vol.  XVII.  I>.  502.  Nov.,  '20. 

(E)    Chan.   R.   Rikcr.      \V-5n0.   p.   501. 

REFRIGERATING   Machines— QB,   2046. 

The  Elictrically-Opcrated  Gyratory  RIDDLE 
— C.  A.  M.  Weber.  1-2,  W-750.  Vol.  XVI.  p. 
263.  June.  '19. 

Stcd  Mills 

First   Reversing   Mill   Drive  in   This   Country 

-  W.  S.  Hall.  South  Chicago  Plant.  Illinois 
Steel  Company.  1-3.  W-1050.  Vol.  XVIII.  p. 
400.  Sept..  '21. 


T-2.  C-1.  1-3.  W-3300.  Vol.  XVI.  p.  69. 
Feb..  '19. 

Electrically-Driven  Plate  Mills  of  the  Brier 
Hill  Steel  Company— G.  W.  Haney.  D-1,  1-13. 
W-2600.     Vol.   XVI,  p.   188,  May.  '19. 

Electrical  Equipment  for  60-Inch  Universal 
Plate  Mill— R.  B.  Gerhardt.  D-1,  1-8,  W-2060. 
Vol.  XVII.   p.   .-ies,  Sept..  '20. 

Motor-Driven  Plate  Mills— F.  D.  Egan.  C-3, 
D-2,  1-12,  W-3260.  Vol.  XVIII,  p.  414, 
Sept.,  '21. 

Post-War  Steel  Conditions— Brent  Wiley.  (E) 
W-1110.     Vol.   XVI.  p.  6.  Jan..  '19. 

Motor-Driven  Steel  Mills— Brent  Wiley.  (E) 
W-900.     Vol.   XVI,   p.  357,   Sept.,   '19. 

Electrical  Development  in  the  Iron  and  Steel 
Industry— J.  F.  Kelly.  (E)  W-400.  Vol.  XVI. 
p.   358.   Sept..   '19. 

Electric  Drives  for  Steel  Mills— Brent  Wiley. 
(E)   W-460.     Vol.  XVII.  p.  361.  Sept..  '20. 

Electrical  Developments  in  the  Iron  and  Steel 
Industry— R.  B.  Gerhardt.  (E)  W-750.  Vol. 
XVIII.  p.  383.  Sept..  '21. 

The  Application  of  Adjustable  Speed  Main 
Drives  in  the  Steel  Mill — Gordon  Fox  and 
Arthur  J.  Whitcomb.  C-1.  D-2,  1-8,  W-2820. 
Vol.   XVII.   i>.   367,   Sept..   '20. 

The  Cost  of  Interruptions  of  Power  to  Steel 
Mills— E.  S.  Jeffries.  T-1,  W-1400.  Vol.  XVII. 
p.  371,  Sept.,  '20. 

Oil  Circuit  Breaker  Arrangements  and 
Switching  Schemes  for  Steel  Mills— G.  P. 
Wilson.  C-1,  D-14.  W-5250.  Vol.  XVn,  p. 
402,  Sept.,  '20. 

The  Electric  Motor  in  the  Steel  Mill— G.  E. 
Stoltz.  (E)  W-560.  Vol.  XVII,  p.  360, 
Sept.,   '20. 

The  Design  of  Large  Induction  Motors  for 
Steel  Mill  Work— H.  L.  Barnholdt.  C-1.  1-8, 
W-2450.     Vol.   XVI.   p.   251,  June.   '19. 

Insulation  for  Steel  Mill  Motors— J.  L.  Ry- 
lander.  1-2.  W-2900.  Vol.  XVIII,  p.  405. 
Sept.,   '21. 

Power-Factor  Correction  in  Steel  Mills— H. 
K.  Sels.  T-2,  C-4,  1-3.  W-2850.  Vol.  XVIII. 
p.   419.   Sept.,  '21. 


THE  ELECTRIC  JOUR.WIL 


Reducing:  Mechanical  Difficulties  with  Motor- 
Driven  Applications — R.  Pruger  and  L.  A. 
Deesz.  1-9.  W-1050.  VdI.  XVIII.  p.  408. 
Sept.,    '21. 

(E)    G.  M.  Eaton.     W-100.  p.  384. 

Induction  Motor  Drive  for  Skip  Hoists— F.  R. 
Burt.  C-2.  D-1,  I-l.  W-1250.  Vol.  XVI,  p.  381. 
Sept.,  '19. 

Marine 

Electrical  Propulsion  for  Battleships— Wil- 
fred Sykes.  (E)  W-1050.  Vol.  XVIII.  p. 
237.  June,  '21. 

The  Battleship  is  a  Fighting  Ship— W.  S. 
RuKtr.         (E)       W-800.       Vol.    XVIII,    p.    238, 


Juii 


•21. 


Electric  Drive  and   the  U.  S.  S 

H.  M.  Southpate.  Illustrations  of  ship's  offi- 
cers. 1-9,  W-1660.  Vol.  XVlll.  p.  239. 
June.  '21. 

Motion — $30,000,000  Worth— Commander  n. 
A.  Bachmann.  M.  C.  U.  S.  N.  The  trial  trip 
of  the  Tennessee.  I-l.  W-2.'>00.  Vol.  XVIII, 
p.   245.  Ju 


'21. 


General  Arrangement  of  Propelling  Machin- 
ery of  the  U.  S.  S.  Tennessee— W.  E.  Thau. 
C-4,  1-6,  W-4100.  Vol,  XVIII.  p.  245.  June.  '21. 

The  Propelling  Motors  of  the  U.  S.  S.  Ten- 
ncssec— H.  L.  Barnholdt.  T-1.  D-1.  1-13. 
W-3820.     Vol.  XVIII.  p.  251.  June,  '21. 

The  Control  Room  Circuit  Breaker  Equip- 
ment of  the  U.  S.  S.  Tennessee- E.  K.  Read. 
I-IO.   W-3200.      Vol.    XVIII.   p.    258.   June,    '21. 

The  Control  Equipment  of  the  Propelling 
Machinery  of  the  U.  S.  S.  Tennessee— M.  Cor- 
ne'ius.  D-1,  1-4.  W-6600.  Vol.  XVIII.  p.  263. 
June.    '21. 

Lighting  Sets  on  the  U.  S.  S.  Tennessee— 
J.  A.  MacMurchy  and  Albert  O.  Loomis.  1-2, 
W-1890.     Vol.   XVIII.   p.   271.  June.   '21. 

Condensing  Equipment  and  Oil  Cooling  Sys- 
tem for  the  U.  S.  S.  Tennessee — John  H. 
Smith  and  Albert  O.  Loomis.  T-1.  1-8. 
W-3480.     Vol.  XVIII.  p.  273.  June,  '21. 

The  Control  of  the  Secondaries  of  the  Main 
Propulsion  Motors  of  the  V.  S.  S.  Tennessee — 
W.  C.  Goodwin.  1-3.  W-1300.  Vol.  XVIII.  p. 
278.  June.  '21. 

The  Stability  Indicator  tor  the  U.  S.  S.  Ten- 
nessee—R.  T.  Pierce.  D-1.  W-790.  Vol.  XVIII. 
p.  280.  June.  '21. 

Main  Turbine  and  Turbine  Speed  Control 
for  the  U.  S.  S.  Tennessee— W.  B.  Flanders. 
1-7,  W-2060.     Vol.  XVIII.  p.   281.  June,  '21. 

The  Main  Generators  of  the  U.  S.  S.  Ten- 
nessee—R.  E.  Oilman.  C-3.  1-5.  W-2040.  Vol. 
XVIII,  p.   284.  June,   '21. 

The  Nerve  Center  of  the  Tennessee — C.  B. 
Mills.  The  Gyroscopic  compasses  and  fire  con- 
trol system.  1-3,  W-840.  Vol.  XVIII,  p.  288. 
June.   '21. 

The  Gyro  Stabilizer  for  Ships — E.  A.  Sperry. 
(E)    W-700.      Vol.   XVIII,   p.   335.  Aug..   '21. 

The  Gyroscopic  Stabilizer  on  the  *'Lyn- 
donia" — Alexander  E.  Schein.  I-IO,  W-45G0. 
Vol.   XVIII.   p.   331),  Aut;.,   '21. 

The  Construction  of  the  "Lyndonia"  Sta- 
bilizer—W.  T.  Manning.  1-2,  W-1660.  Vol. 
XVIII,  p.  342,  Aug.,  '21. 

The  Electrical  Equipment  for  the  "Lyn- 
donia" Stabilizer— T.  P.  Kirkpatrick  and  H. 
C.  Coleman.  1-5,  C-5,  W-3450.  Vol.  XVIII,  p. 
344.    Aug..    '21. 

Electrical  Equipment  Used  on  Submarines — 
H.  C.  Coleman.  T-1.  1-9.  W-3120.  Vol.  XVI. 
p.  295.  July.  '19. 


Texlile 
Electricity    in    the    Textile    Indnitry— J.    R. 

Olnhausen.  (E)  W-1000.  Vol.  XVIII.  p.  486. 
Nov.,  '21. 

Electrification  of  New  England  Texlile  MilU 
— G.  D.  Bowne.  Jr.  (E)  W-900.  Vol.  XVIII. 
p.  486,  Nov..  '21. 

The  Central  Station  and  the  Textile  Mill— 
F.  S.  Root.  1-7.  W-1300.  Vol.  XVIII.  p.  487. 
Nov..  '21. 

Modernized  Plant  of  Prudential  Worsted  Co. 
-J.  B.  Parks.  1-4.  W-1050.  Vol.  XVIII.  p. 
489.   Nov..   '21. 

The  Textile  Industry  in  the  South— John 
Gelzer.  T-1.  C-6.  1-6.  W-1700.  Vol.  XVIII.  p. 
491.   Nov.,  '21. 

The  Design  of  Induction  Motors  for  Textile 
Service  O.  C.  Schocnfcld.  1-6.  W-5400.  Vol. 
XVIII.  p.   494.   Nov..   '21. 

Individual  Motor  Drive  for  Spinning  and 
Twister  Frames— George  Wrigley.  T-1.  1-2, 
1-3,   W-1900.     Vol.   XVIII,  p.   501.  Nov..  '21. 

Motors  for  Textile  Finishing  Plants— War- 
ren B.  Lewis.  W-3500.  Vol.  XVIII.  p.  604. 
Nov..  '21. 

Central  Station  Power  for  Textile  Mills — 
John  W.  Vox.  W-1520.  Vol.  XVIII.  p.  607, 
Nov..  '21. 

Adjustable  Speed  Motors  and  Control  in  Fin- 
ishing Plants— C.  W.  Babcock.  1-4,  W-1900. 
Vol.    XVIII,    p.   609.    Nov..    '21. 

Silk  Throwing  and  Electric  Drive- C.  T. 
Guilford.     I-ll.    W-1560.      Vol.    XVIII,    p.    612. 


No 


'21. 


I  \- hides 

Battery  Capacity— QB.  1739. 
(.ias  lingiiies 
(Electrical  Applications  to) 

Regulation  of  Automatic  Generators  W.  A. 
Dick.  C-4.  D-7.  W-2660.  Vol.  XVI,  p.  148, 
Ajir..  '19. 

Winding   Third   Brush   Generator— QB,    1924. 

Heating  Apparatus 

Enameling  in  the  Automobile  Industry— M. 
R.  Armstrong.  T-1,  C-1.  1-7.  W-1450.  Vol. 
XVlll.   p.  6,  Jan..   '21. 

The  Automatic  Electric  Bake  Oven — John  M. 
Strait  and  J.  C.  Woodson.  T-1,  C-2,  D-1,  1-9. 
W-2200.      Vol.  XVlll.  p.   296.  July.   '21. 

Electricity  in  Celluloid  Manufacture — E.  W. 
Manter.  1-6.  W-890.  Vol.  XVI.  p.  94. 
Mar..   '19. 

Automatic  Electric  Enameling  Oven — F.lbert 
Kramer.  At  Forderer  Cornice  Works.  San 
Francisco.  C-1.  1-3.  W-1060.  Vol.  XVIII.  p. 
82.  Mar..  '21. 

Electrically-Heated  Metal  Pattern  Plates  on 
Molding  Machines— EH.    XVI.  229. 

Industrial  Electric  Heating— Wirt  S.  Scott. 
1-13.  W-2000.     Vol.  XVII.  p.   188,  May,  '20. 

Electric  Dryer— QB,  1858. 

Energy    for    Heating   Buildings— QB.    1916. 


Welding 

Arc  Welding  Equipment  in  the  Foundry— 
W.  W.  Reddie.  1-10.  W-1860.  Vol.  XVlll.  p. 
90.  Mar..   '21. 

Electric  Welding  as  a  Factor  in  Reclamation 
-ROD,  XVIII,  483. 

Apparatus  for  Arc  Welding— QB,  1735. 

With  220  Volt  Direct-Current  Circuit— QB, 
1879. 

Generator  for— QB.  1997. 


Magnets 

Effect  of  Voltage  and  Frequency  Chanfei  en 
Number  of  Turns     QB.  1834. 

Demagnetizing    Tool.— QB.    1878. 

Detector  for  Iruii— QU.  1892. 

Flux  Density  of  Permanent  Magnets  -QB. 
1985. 

Magnetic  Brakes— QB.  2029. 

INTKLLir.KNCK  TRANS.MISSION 

Telegraphy 

A  Iligh-Frequcncy  tienerator  for  Alrplan» 
Wireless  Telegraph  Sets— A.  Nyman.  C-6. 
D-4,  1-7,  W-3000.     Vol.  XVI.  p.   140,  Apr..    19. 

Telephony 

Dynamotors  and  Wind-Driven  Generators 
for  Kadiotelephony- R.  li.  Thompson.  C-4. 
D-2.   1-6.   W-4200.      Vol.   XVI.   p.   211.  May.  '19 

Development  of  Airplane  Itadiolelephone  Sal 
—  H.  M.  Stollcr.  C-3.  D-2.  1-6.  W-;30O.  Vol. 
XVI.  p.   211.  May.  '19. 

Telephone  Interference— QB.  1723. 

Radio 

Radio— Its  Future  II.  P.  Davis.  (E)  W-800. 
Vol.  XVIII.  p.   109.  Apr..  '21. 

Radio — Its  Relation  to  the  Electrical  Indus- 
Iry— W.  S.  Rugg.  (E)  W-460.  Vol.  XVIII.  p 
109,  Apr..  '21. 

An  Early  High  Frequency  Alternator— D.  G. 
Lamme.  (E)  W-66U.  Vol.  XVIII,  p.  llo. 
Apr..  '21.  ,    ^ 

Epoch  Making  Radio  Inventions  of  Fessen- 
den— S.  M.  Kintner.  W-1360.  Vol.  XVIII.  p. 
111.   Apr..  '21.  ,      „ 

The  Lafayette  Radio  Station  Commanders. 
C.  Hooper.  U.  S.  N.  1-2.  W-1060.  Vol.  XVlll. 
p.  112,  Apr..  '21. 

Description  of  a  Unl-Wavc  Signaling  Sys- 
tem for  Arc  Transmitters— Lieut.  W.  A.  Eaton. 
U.  S.  N.  1-2.  W-1650.  Vol.  XVIII.  p.  114. 
Apr..  '21. 

The  Heterodyne  Receiver — John  V.  L. 
Hogan.       1-9.    W-2960.      Vol.    XVIII.    p.     116. 

The  Foundations  of  Modern  Radio  I.  W. 
Chubb  and  C.  T.  Allcutt.  W-2M0.  Vol. 
XVlll.  p.   120.  Apr..   '21. 

Static  Frequency  Doublers— J.  F.  Peters.  C-I. 
1-2.  W-1100.     Vol.  XVIII.  p.   122.  Apr..  '21. 

Continuous  Wave  Radio  Communication- D. 
G.    Little.      I-G.    W-3580.      Vol.    XVIII.    p.    124. 

Why     High     Frequency     for     Radiation? — J. 

Slepian.  1-6.  W-2260.  Vol.  XVIII.  p.  129. 
Apr..  '21.  ^       „  t 

Data  and  Tests  on  10,000  Cycle  Per  Second 
Alternator— B.  G.  Lamme.  C-6.  I-«.  W-2660. 
Vol.   XVIII.  p.  132.  Apr..  '21. 

Continuous  Wave  Radio  Receivers— M.  C. 
Batsel.  C-1.  1-9.  W-4170.  Vol.  XVIII.  p.  U«. 
Apr..  '21.  „ 

Radio  Arc  Transmitters— Q.  A.  Brackett. 
1-6.  W-2960.     Vol.  XVIII.  p.   142.  Apr..  '21. 

Remote  Control  by  Radio^A.  L.  Wilson. 
T-1.  D-3.  W-2160.  Vol.  XVIII.  p.  146. 
Apr..  '21. 

Standardization  of  Electric  Indicating  In- 
struments for  Use  with  Radio  Apparatus- d. 
Y.  Allen.  T-1,  C-1,  1-13.  W-4000.  Vol.  XVI. 
p.   494,  Nov..  '19. 

The  Regenerative  Circuit — Edwin  H.  Arm- 
strong- W-1780.  Vol.  XVIII.  p.  153. 
Apr..   '21. 

The  Dry  Cell  Radio  Vacuum  Tube— Harry 
M.    Ryder.     C-4.    1-4.   W-1360.     Vol.   XVIII.   p. 


D,- 


21. 


RAILWAY    ENGINEERING 

(SEE  ALSO  CONTROLLERS,  P.  8;  AND  SEKIKS   MOTORS.   P.   5) 


GENERAL 


Expansion  of  Railroad  Electrification — F.  H. 
Shepard.  (E)  W-670.  Vol.  XVI.  p.  2. 
Jan..   '19. 

The  Street  Railway  Situation— John  H.  Par- 
dee.     (E)   W-2000.      Vol.  XVI.  p.  405.  Oct..  '19. 

The  Stability  of  the  Electric  Street  Railway 
Industry— W.  S.  Rugs.  (E)  W-1400.  Vol. 
XVI.   p.  406.   Oct..   '13. 

Public  Understanding,  Consideration  and 
Appreciation  Necessary  for  a  Solution  of  the 
Electric  Railway  Problem — Lucius  S.  Storrs. 
(E)   W-800.     Vol.   XVI.   p.   408.  Oct..   '19    . 

City  Traction  Problems- A.  W.  Thompson. 
(E)    W-1200.     Vol.   XVI,   p.   409,  Oct..   '19. 

Inherent  Defects  and  Future  Sphere  of  Use- 
fulness of  Electric  Traction— Edwin  Gruhl.  (E) 
W-900.     Vol.  XVI.  p.  410.  Oct..  '19. 


The  Future  Outlook  for  Large  Urban  Elec- 
tric Railways— F.  G.  Buffe.  (E)  W-1000.  Vol. 
XVI.  p.  411.  Oct..   '19. 

Hold  Fast  to  the  Fundamentals— F.  W.  Hild. 
(E)    W-1120.      Vol.   XVI.   p.  412.  Oct..   '19. 

Utility  Credit  and  General  Prosperity— Theo- 
dore P.  Shonts.  (E)  W-860.  Vol.  XVI.  p.  413. 
Oct..   '19. 

Public  Utilities— A  Diagnosis— Thos.  S. 
Wheelwright.  (E)  W-850.  Vol.  XVI.  p.  414. 
Oct..  '19. 

Moderation  Must  Govern  Future  Municipal 
Action— A.  M.  Lynn.  (E)  W-1100.  Vol.  XVI. 
]..  415.  Oct..  '19. 

Service  at  Cost — Calvert  Townley.  (E) 
W-liir.O.     Vol.   XVI.  p.  416.  Oct..  '19. 

The  Graduated  Fare  System— N.  W.  Storer. 
(E)  W-1360.     Vol.  XVI,  p.  417,  Oct.,  '19. 


Mutuality  of  Interests  in  Practice— Benja- 
min E.  Tilton.  (E)  W-900.  Vol.  XVI.  p.  418. 
Oct..  "19.  „ 

Momentum  of  Custom— Edwin  D.  Dreyfus. 
(E)   W-1220.     Vol.   XVI,  p.  419,  Oct..  '19. 

Co-operation  Between  Operators,  Car  Build- 
ers and  Equipment  Manufacturers  J.  S. 
Tritle.     lE)   W-770.    Vol.  XVI,  p.  421.  Oct..    19. 

Electric  Railway  Passenger  and  freight 
Transportation- r.  E.  Morgan.  1-4.  W-3320. 
Vol.   XVI.   p.  422.  Oct..  '19. 

Municipal  Railway  Operation  at  Seattle — 
Thomas  F.  Morphine.  W-2100.  Vol.  XVI.  p. 
428,  Oct..  '19. 

Things  to  Consider  in  Handling  the  Public— 
W.    H.    Boycc.      W-2260.      Vol.    XVI.    p.    43S. 

The  Electric  Railway  Situation— John  H. 
Pardee.  (E)  I-l.  W-600.  Vol.  XVH.  p.  429. 
Oct..  '20. 


10 


THE  ELECTRIC  JOURNAL 


Specifications  of  a  Successfal  Street  Railw«T 
— W.  S.  Rugg.  (E)  W-700.  Vol.  XVII,  p.  ■ISO. 
Oct..  '20. 

The  Future  of  the  Autobus  as  it  Effects  the 
Electric  Railway— L.  H.  Palmer.  (E)  W-1250. 
Vol.  XVII.  p.  430.  Oct..  '20.  „     ,      „   , 

Constructive  Electric  Railway  Work — Myles 
B.  Lambert.  (E)  W-400.  Vol.  XVII.  p.  432. 
Oct..  '20.  „   .. 

The  Best  Plan  for  Operating  Street  Railways 
— C.  W.  Culkins.  (E)  W-1250.  Vol.  XVII,  p. 
432.  Oct.,  '20. 

Increased  Railroad  Bates  as  an  Accelerator 
of  Electrification  —  Calvert  Ton  niey.  (E) 
W-700.     Vol.  XVII.  p.  433,  Oct.,  '20. 

Service  Versus  Fares— How  Electric  Rail- 
way Companies  are  Making  Use  of  Operating 
Economies  and  Advancement  in  the  Art  to 
Offset  Rising  Costs— J.  W.  Welsh.  (E)  W-1350. 
Vol.   XVII.  p.  435.  Oct..   '20. 

Purchased  Power  for  Traction— H.  L.  Kirkcr. 
(E)    W-115U.      Vol.   XVII.   p.   436.  Oct..   '20. 

Severe  Winter  Operating  Conditions — Prac- 
tical Methods  for  Minimizing  Possible  Troublea 
--John  S.  Dean.  1-14,  W-3550.  Vol.  XVII. 
p.  438.  Oct..  '20. 

The  Bus,  the  Trackless  Trolley  or  the  Trolley 
Car  for  Light  Traction — Which?— L.  M.  As- 
pinwall.     W-2250.     Vol.  XVII.  p.  443.  Oct..  '20. 

Methods  of  Hiring  and  Training  Men  Used 
by  the  Mechanical  Department  of  the  Kansas 
City  Railways— Henry  S.  Day.  1-6,  W-2800. 
Vol.  XVII.  p.  447,  Oct.,  '20. 

Railway  Utilities  Approaching  Stability — A. 
H.  Mclntire.  (E)  W-250.  Vol.  XVIII  .p.  47. 
Feb..   -21. 

The  Problem  of  the  Electric  Railways — 
Myles  B.  Lambert.  (E)  W-1100.  Vol.  XVIII. 
p.    3.  Jan..   '21. 

Drive  Home  the  Facts— P.  H.  Gadsden.  (E) 
I-l.    W-560.      Vol.   XVIII,   p.   427.   Oct..    '21. 

The  Transportation  Business  —  A  World 
Fundamental— M.  C.  Brush.  (E)  W-1300.  Vol. 
XVIII.  p.  430.  Oct..   '21. 

The  Problems  of  the  Street  Railways — John 
H.  Pardee.  (E)  W-2000.  Vol.  XVIII.  p.  432. 
Oct..   '21. 

The  Problem  of  Mass  Transportation — Ed- 
ward Dana.  (E)  W-1700.  Vol.  XVIII.  p.  434. 
Oct..   '21. 

The  Outlook  for  the  Neit  Five  Years— Philip 
J.  Kealy.  (E)  W-1650.  Vol.  XVIII.  p.  435. 
Oct..   '21. 

The  Development  of  Rapid  Transit  Lines — 
Britton  I.  Budd.  (E)  W-1800.  Vol.  XVIII.  p. 
437.  Oct.,  '21. 

Futures— Calvert  Townley.  (E)  W-1000. 
Vol.  XVIII.  p.  438.  Oct..  '21. 

The  Trackless  Trolley  or  Trolley  Bus — Thos. 
S.   Wheelwright.      (E)    W-550.     Vol.   XVIII.   p. 

439.  Oct..   '21. 

Outlook  for  the  Electric  Railway  Industry — 
Henry  A.   Blair.      (E)   W-1950.     Vol.  XVIII.  p. 

440,  Oct..  "21. 

Dealing  with  the  Public  and  Employes — 
Harry  Reid.  (E)  W-1250.  Vol.  XVIII.  p. 
442,   Oct..   '21. 

The  Relation  of  the  Electric  Railway  to  the 
Community  —  Arthur  W.  Thompson.  (E) 
W-1500.     Vol.   XVIII.  p.   443.  Oct..   '21. 

The  Standard  Types  of  City  Cars  the  Coun- 
try Really  Needs  to  Meet  Traffic  Requirements 
— W.  H.  Heulings.  Jr.  (E)  W-1000.  Vol. 
XVIII.  p.  447.  Oct..   '21. 

Wasting  Capital  in  Bus  Competition — Edwin 
D.  Dreyfus.  (E)  W-850.  Vol.  XVIU,  p.  448. 
Oct..   '21. 

Encourage  Young  Engineers  to  Enter  Rail- 
way Organizations — H.  H.  Johnson.  (E) 
W-1420.     Vol.   XVIII,  p.  449.  Oct..   '21. 

The  Electric  Railway  and  the  Jitney — F.  G. 
Buffe.  (E)  W-2100.  Vol.  XVIII,  p.  460. 
Oct..   •21. 

An  Appeal  to  Manufacturers  and  Dealers — 
Barron  G.  Collier.     (E)  W-300.     Vol.  XVIII.  p. 

452.  Oct..   '21. 

Electric  Railway  and  Welfare  Work— Joseph 
H.    Ale.\andcr.      1-4,    W-3750.      Vol.    XVIII,    p. 

453,  Oct..    '21. 

The  Problem  of  Street  Congestion — Thomas 
Fitzgerald.  W-4600.  Vol.  XVIU,  p.  457. 
Oct.,   '21. 

The  Value  of  Association  of  ttie  Mechanical 
Departments  of  Electric  Railwavs — F.  G.  Hick- 
ling.     W-1100.     Vol.   XVni.   p.   480,   Oct.,    '21. 

SYSTEMS 
Direct  Current 


II — Transformer  Equipment — W.  M.  Dann. 
1-6.  W-1350.     Vol.  XVII.  p.  9,  Jan.,  "20. 

Ill— 3000  Volt  Motor-Generator  Sets— David 
Hall.  T-2.  06.  1-3.  W-1660.  Vol.  XVII,  p. 
12,    Jan..    '20. 

IV — Substation  Switching  Equipment — C.  M. 
McL.  Moss.  1-8.  W-1250.  Vol.  XVII.  p.  16. 
Jan..  '20. 

V — The  Power  Indicating  and  Limiting  Ap- 
paratus—B.  H.  Smith.  I-IO,  W-2700.  Vol. 
XVII.  p.  46.  Feb..  '20. 

VI — The  Axle-Generator  Regenerating  Sys- 
tem—R.  E.  Ferris.  C-3.  D-1.  W-1800.  Vol. 
-XVII.  p.  46,  Feb..  '20. 

(E)   W.  R.  Stinemetz.     W-450.  p.   39. 

VII — The  New  Passenger  Locomotives — N. 
W.  Storer.  I-l.  W-155a.  Vol.  XVII.  p.  84. 
Mar.,   '20. 

VIII — Auxiliary  Rotating  Apparatus — R.  E. 
Ferris.  C-2.  D-1.  I-IO.  W-1500.  Vol.  XVII.  p. 
128.  Apr..   '20. 

IX— The  Electrical  Equipment  and  Control- 
P.  L.  Mardis.  T-1.  D-4.  1-14,  W-5000.  Vol. 
XVII.   p.  235.  June.   '20. 

X — The  Auxiliary  and  Lighting  Control 
Equipment — John  A.  Clarke,  Jr.  D-2.  1-8. 
W-2600.     Vol.  XVII.   p.   244.  June.   '20. 

XI  -Layout  of  Apparatus  in  the  Cab — C.  C. 
Whittaker.  D-1,  1-2.  W-1200.  Vol.  XVII,  p. 
249.  June.  '20. 

XII— 3000  Volt  Current  Collectors  —  W. 
Schaake.  C-1.  D-1,  1-7,  W-1950.  Vol.  XVH, 
p.    278.   July,    '20. 

XIII  Main  Driving  Motors  —  Gerald  F. 
Smith.  T-1.  C-1.  D-1,  1-9,  W-1900.  Vol.  XVII, 
p.  284.  July.  '20. 

XIV — Heating  Passenger  Coaches — H.  G. 
Jungk.  D-1.  1-1.  W-1250.  Vol.  XVII,  p.  324, 
Aug..    '20. 

Snow  Fighting  Methods  on  the  Electrified 
Section  of  the  Chicago,  Milwaukee  &  St.  Paul 
Railroad— E.  Scars.  1-3.  W-1250.  Vol.  XVIII. 
p.  39.  Jan..  '21. 

Electric  Braking  of  Direct-Current  Vehicles 
— W.  M.  Hutchinson.  D-5.  W-1600.  Vol. 
XVII.  p.  471.  Oct..  '20. 

Electrification  of  the  Central  Limones,  Cuba 
—  O.  Wortman-  D.l,  1-4.  W-2200.  Vol.  XVII. 
p.  477.   Oct..  '20. 


Single  Phase 

Single-Phase  in  Thirteen  Years'  Successful 
Operation  on  the  Erie— Q.  W.  Hershcy.  1-3. 
W-2750.      Vol.   XVII.   p.   460,   Oct.,    '20. 

Reminiscences  of  the  Erie  Electrification  at 
Rochester— W.  N.  Smith.  W-1980.  Vol. 
XVIII,  p.  40,  Jan..  '21. 

Result  of  Twelve  Years'  Heavy  Haulage  on 
the  Single-Phase  Electrification  of  the  Grand 
Trunk  Railway  System  —  R.  L.  Hermann. 
W-1450.     Vol.   XVII.   p.   480.   Oct..  '20. 

Regulation  and  Inductive  Effects  in  Single- 
Phase  Railway  Circuits- A.  W.  Copley.  T-1. 
C-1.  D-23.  W-10550.  Vol.  XVII,  p.  326, 
Aug.,  '20. 

Renewal  of  the  Catenary  Construction  in 
the  Hoosae  Tunnel — L.  C.  Winship.  1-4. 
W-2750.     Vol.  XVIII.  p.  84.  Mar.,   '21. 


MOTIVE  POWER 

Electric    Railway    Freight    Haulage — A.     B. 

Cole.     1-6.  W-3250.     Vol.  XVI.  p.  463,  Oct..  '19. 

Freight  Service  on  Electric  Railways — T.  H. 
Stoffel.  1-3.  W-2470.  Vol.  XVIII.  p.  474, 
Oct.,   '21. 

Decreased  Operating  Costs  with  Helical  Gears 
— G.  M.  Eaton.  1-2.  W-30UU.  Vol.  XVI.  p. 
430.  Oct..  '19. 

Selection  of  Motors  for  Service  Conditions— 
F.  E.  Wynne.  (E)  W-600.  Vol.  XVII.  p. 
434.   Oct..   "20. 

Multiple  Unit  Train  Operation  —  S.  B. 
Schenck.  D-1.  1-6.  W-2300.  Vol.  XVII.  p.  457. 
Oct..   '20. 

Use  and  Abuse  of  Electric  Motors — J.  M. 
Hippie.  T-1.  W-1250.  Vol.  XVm,  p.  462. 
Oct..  •21. 


I — The  Electric  Power  Supply  for  the  Puget 
Sound  Lines— A.  W.  Copley.  D-4.  1-12.  W-1950. 
Vol.  XVII,  p.  3.  Jan.,  '20. 

(E)  F.  H.  Shepard.     W-600,  p.  1. 


Locomotives 

Comparison  of  Low-Speed  and  High-Speed 
Interurban  Freight  Locomotives — D.  C.  Hersh- 
berger.  C-3.  1-2,  W-3150.  Vol.  XVI.  p.  436. 
Oct.,  '19. 


Remotely  Controlled  Electric  Locomotives  in 
the  By-Product  Coke  Industry— H.  H.  John- 
ston. D-S.  I-l.  W-1750.  Vol.  XVII,  p.  49, 
Feb.,   '20. 

(E)    L.  G.   Riley.     W-350,  p.  39. 

The  New  Passenger  Locomotives  for  the  Chi- 
cago. Milwaukee  &  St.  Paul  Railroad— N.  W. 
Storer.  I-l.  W-1550.  Vol.  XVII,  p.  84. 
Mar..   '20. 

Industrial  Type  Electric  Locomotives  in 
Steel  Mill  Operations — H.  H.  Johnston.  1-9. 
W-3000.     Vol.  XVII,   p.. 392.   Sept..   '20. 

A  Slip  Arrester  for  Heavy  Electric  Locomo- 
tives—C.  C.  Whittaker.  1-5,  W-650.  Vol.  XVII. 
p.   446.  Oct..  '20. 

The  New  Liquid  Rheostats  for  the  Norfolk  & 
Western  Locomotives— D.  C.  West.  1-1. 
W-1600.     Vol.  XVII.  p.   483.   Oct..   '20. 

Haul  Freight  the  Electric  Way  by  Use  of 
Standard  Freight  Equipment — E.  D.  Lynch. 
W-1500.     Vol.   XVII.  p.   495.  Oct..   '20. 

Cars 

The  Safety  Car— N.  H.  Callard.  Jr.  C-3, 
1-3.  W-6000.     Vol.  XVI.  p.  447.  Oct..   '19. 

Service  with  the  Safety  Type  Car— E.  A. 
Palmer.  T-1.  I-l.  W-1700.  Vol.  XVI.  p.  426. 
Oct..  '19. 

The  Future  of  the  Birney  Safety  Car — Luke 
C.  Bradley.  (E)  W-400.  Vol.  XVI.  p.  419. 
Oct..  '19. 

Construction  of  Semisteel,  Front-Entrance. 
Side-Exit  Cars— M.  O'Brien.  T-1,  1-2.  W-1550. 
Vol.   XVIII.  p.   468.  Oct..   '21. 

Safety  Car  Operating  Results- C.  L.  Doub. 
C-2.  1-2.  W-2300.     Vol.  XVIII,  p.  477.  Oct..  '21. 

Failure  of  Electric  Car  Center  Plates  yB. 
1998. 

Stopping  a  Car  by  Braking  with  the  Molars 

ROD.   XVIII.  334. 

Shape  of  Car  Wheel- QB.   1984. 

Equipment 

3000  Volt  Current  Collectors  for  the  Chicago. 
Milwaukee     &      St.      Paul      Locomotives        W. 

Schaake.     C-l.  D-1.  1-7.  W-1950.     Vol.  XVII.  p. 
278.   July.   '20. 

Maintenance  and  Repair 

Tho  Logical  Unit  for  Comparing  Repair 
Costs  of  Electric  Locomotives  and  Cars — Hugh 
Pattison.  W-1850.  Vol.  XVII.  p.  476. 
Oct..  '20. 

Inspection  and  Overhauling  of  City  and  In- 
terurban Cars— W.  W.  Cook.  W-4700.  Vol. 
XVI.  p.  519.  Dec..  '19.  (E)  M.  B.  Lambert. 
W-1150.  p.  507. 

The  Maintenance  of  Railway  Equipment — F. 
W.  McCloskey.  W-1550.  Vol.  XVII,  p.  469. 
Oct..   '20. 

Shop  Facilities  for  Maintenance  of  Railway 
Equipment  H.  A.  Leoiihauser.  T-1.  I-l. 
W-3200.      Vol.   XVIII.  p.   464.   Oct..   '21. 

Inspection  and  Maintenance  of  Direct- 
Current  Car  Control- A.  H.  Candee.  W-3600. 
Vol.   XVII.  p.   492.  Oct..  '20. 

Expanding  Bronze  Bearings — C.  M.  Cross. 
I-l.  W-1170.     Vol.  XVII,  p.  462.  Oct.,  '20. 

Dad.    the    Inspector,    on    Co-operation — L.    J. 
Davis.      W-I080.     Vol.   XVI.  p.  39.  Jan..   '19. 
RAILWAY  OPERATING  DATA 

Railway  Motor  Testing— ROD,  XVI.  40. 

Armature  Testing— ROD.  XVI.  76. 

Testing  Motor  Fields— ROD.  XVI,   110. 

Testing  Assembled  Railway  Motors— ROD. 
XVI.   158. 

Locating  and  Repairing  Armature  Wind- 
ing Troubles — ROD.  XVI.  230. 

Mounting  and  Maintenance  of  Car  Resistors 
—ROD.    XVI.   269. 

Removing  and  Replacing  Railway  Motor  Ar- 
mature Shafts— ROD.   XVI.  311. 

Maintenance  of  Magnet  Valves — ROD.  XVI.  - 
p.    353. 

Maintenance  of  Fuse  Boxes  for  Railway 
Service— ROD.  XVI.  p.  399. 

Does  it  Pay  to  Dip  and  Bake  Armatures? — 
ROD.   XVI.   p.   467. 

Lubrication  of  Control  Apparatus — ROD. 
XVI.   p.   468. 

Shop    Organization— ROD.    XVI.   p.    606. 

Systematic  Inspection  of  Car  Equipments — 
ROD.  XVI.  p.  637. 

Repairing  Loose  Housings  on  Split  Frame 
Motors— ROD,  XVU,  p.  36. 


THE  ELECTRIC  JOURNAL 


Key  for  Railway  Equipment  Repairs — ROD, 
XVII,   p.   126. 

Method  of  Connecting  Car  Wiring  to  Motor 
Leads   and  Ground~ROD,   XVII,   p.   li;,s. 

Armature  Trouble  Resulting  from  Brol<en 
Motor    Leads— ROD,    XVII,   p.    231. 

Field  Winding  Diagrams  for  Railway  Motors 
—ROD,  XVII,  p.  272;  p.  358;  p.  428. 

Voltage  Testing  of  Control  Equipment— 
ROD.  XVII.  p.  318. 


Armature  Winding  Diagrams  for  Railway 
Motors— ROD,   X\  II,   p.   499. 

Checking  Armature   and  Axle  Bearing  Wear 

—ROD.  XVII,  p.  r>ss. 

Types  of  Transition  Used  to  Obtain  Series- 
Parallel   Operation      ROD,    XVIII,   40. 

The    Handling   of    Copper— ROD,    XVIII,    76. 

Armature  Record  Tags     ROD,  XVIII.  p,  108. 

First  Aid  for  Electrical  Injury— ROD, 
XVIII,  156. 

Stopping  a  Car  by  Braking  with  the  Motors 
—ROD.  XVIII.  :i34. 


Bearing    SheU>- 

.VVllI,    38U. 

The  Assembly  of  Complete  Sets  of  Commu- 
tator  Segments     ROD.    XVIII,   424. 

Electric  Welding  as  a  Factor  in  Keclamalion 
—  ROD,   XVIII,  483. 

Grid   Resistance  Design  -ROD.  XVIII.  5S6. 

.MINING 

Turning  Wheels— QB.   1709. 

Wrenches   for   Mine   Locomolires— QB.  1841. 


MISCELLANEOUS 


GENERAL 

The  Polar,  Multi-Exposure.  High-Speed 
Camera- J.  W.  Legg.  1-5,  W-1750.  Vol.  XVI. 
p.  509,  Dec.  "19. 

(E)    R.   P.   Jackson.     W-300.  p.   607. 

Proposed  Changes  in  the  American  Patent 
System- Wesley  G.  Carr.  W-1270.  Vol.  XVI, 
p.   299,  July,   -19. 

Preparation  of  Technical  Papers— B.  G. 
Lamme.     W-2000.     Vol.  XVI,  p.  383,  Sept.,  '19. 

First  Aid  for  Electrical  Injury— ROD,  XVIII, 
156. 

Relative  Merits  of  Stop   Watches— QB,    1947. 

Exploring  Coil  to  Locate  Underground  Iron 
Pipes— QB,  1973. 

Reclaiming  Waste  and  Rags— QB,  1991. 

Thermophone — QB,  2026. 


THE  ENGINEER 
Education 

Student  Army  Training  Corps — C.  R.  Dooley. 
(E)    W-680.     Vol.  XVI,   p.   46.  Feb..  '19. 

Education  of  Radio  Engineers— H.  M.  Tur- 
ner.     W-1100.      Vol.    XVIII.   p.    149,    Apr..    '21. 

Westinghouse  Technical  Night  School— W. 
W.  Reddie.  T-1,  C-1.  I-l,  W-1530.  Vol. 
XVIII,  p.  150,   Apr.,   '21. 

Personal 

Benjamin  G.  Lamme — E.  M.  Herr.  (E) 
W-700.     Vol.  XVI.  p.  233.  June.  '19. 

The  Edison  Medal— Calvert  Townley.  (E) 
W-550.     Vol.  XVI.  p.  233.  June.   '19. 

The  Achievements  of  Benjamin  G.  Lamme — 
B.  A.  Behrend.  Address  of  presentation  of  the 
Edison   Medal.     I-l,  W-3400,   p.   235.     Response 


to  address  of  presentation  —  Benjamin  G. 
Lamme.  I-l.  W-5260.  Vol.  XVI.  p.  238. 
June,  '19. 

Thirty  Years  of  Service  to  the  Electrical 
Industry— A.    H.    Mclntirc.      (E)    A   Tribute    to 

B.  G.  Lamme.  W-800.  Vol.  XVI.  i>.  359, 
Sept..   '19. 

Calvert  Townley,  President  American  Insti- 
tute of  Electrical  Engineers — Lewis  Buckley 
Stillwell.  I-l,  W-2700.  Vol.  XVI,  p.  276, 
July,  -19. 

A  Tribute  to  Albert  Schmid— C.  A.  Terry. 
I-l.  W-1750.     Vol.   XVII,  p.  40,   Feb.,  '20. 

Charles    Wood    Johnson— An    Appreciation — 

C.  F.  Scott.  I-l,  W-1000.  Vol.  XVII,  p.  234. 
June.    "20. 


WORKS  MANAGEMENT 

Engineers  Should  Study  Cost  Accounting — 
Samuel  E.  Duff.  (E)  W-700.  Vol.  XVII.  p. 
1,  Jan.,   '20. 

New  South  Philadelphia  Plant  of  Westing- 
house  Electric  &  Mfg.  Co.— H.  T.  Herr.  1-22, 
W-41:?(l.      Vol.   XVI,   p.    114,   Apr.,   '19. 

(E)    Calvert  Townley.     W-1660,   p.   HI. 

Manufacturing  Scheme  of  the  South  Phila- 
delphia Works— Oscar  Otto.  I-ll,  W-2250.  Vol. 
XVI,  p.  122.  Apr.,  '19. 

Power  System  of  the  South  Philadelphia 
Works— Graham  Bright.  1-13.  W-3200.  Vol. 
XVI.  p.  12G.  Apr.,  '19. 


ENGINEERING  SOCIETIES 

Local  Associations  for  Organization  Better- 
ment—W.  G.  Brooks.  W-800.  Vol.  XVI,  p. 
464,  Oct.,  '19. 


N.  E.  L.  A. 

The  National  Electric  Light  Association  for 
1919- W.  F.  Wells.  (E)  W-670.  Vol.  XVI.  p. 
163.    May,   '19. 

The  National  Electric  Light  Association  Con- 
vention at  Pasadena  K.  II.  Ballard.  (E) 
W-900.     Vol.  XVII.  p.  173.  May.  '20. 

Proposed  Reorganization  of  N.  E.  L.  A. — M. 
H.  Aylesworlh.  I-l.  W-2500.  Vol.  XVII.  p. 
227.  May,  '20. 

The  National  Electric  Light  Association- 
Martin  J.  Insull.  (E)  I-l,  W-900.  Vol.  XVIII, 
p.  157,  May,  '21. 

Constructive  Suggestions  by  a  Past  Presi- 
dent- R.  H.  Ballard.  (E)  W-850.  Vol.  XVIII. 
p.  158.  May.  '21. 

The  Manufacturer  and  the  N.  E.  L.  A.— 
Frank  W.  Smith.  (E)  W-950.  Vol.  XVIII.  p. 
160.  May.   '21. 

The  Technical  Work  of  the  National  Electric 
Light  Association-  -I.  E.  Mouitrop.  (E)  W-550. 
Vol.  XVIII.  p.  161.  May.  '21. 

Now  for  the  N.  E.   L.  A.  Convention- E.  H. 
Sniinn.        (E)      W-670.        Vol.     XVIU.     p.     168. 
May.  '21. 
A.  I.  S.   E.  E. 

The  Association  of  Iron  &  Steel  Electrical 
Engineers— D.  M.  Petty.  (E)  W-800.  Vol. 
XVI.  p.  357.  Sept..  '19. 

The    Growth    and    the    Accomplishments    of 

The   Assoc,    of    I.   &   S.    E.    E B.    W.   Gilson. 

(E)  W-IOGO.  I-I.     Vol.  XVII.  p.  359.  Sept..  '20. 

The  Association  of  Iron  and  Steel  Electrical 
Engineers— Ernest  S.  Jefterics.  (E)  1-1.  W-660. 
Vol.   XVIII.  p.  381,  Sept.,  '21. 

THE  JOURNAL 

The  Journal— A  Teit  Book  Chas.  R.  Riker. 
(E)   W-250.     Vol.  XVI.  p.   83.  Mar..  '19. 

Question  Box  Service— C.  R.  Riker.  (E) 
W-200.     Vol.  XVIII.  p.  335.  Aug..  '21. 


1^ 


THE  ELECTRIC  JOURNAL 


INDEX    TO    AUTHORS 


AIMUTIS.  F.  J.  ^,„    ^ 

Armature  Slot  Wedges XVI:  Dec, 

ABBOTT,  S.  H.  ,  o- 

Exnerience  in  Drying  Out  Large   Irans- 

foi-mers       XVIU  :   Mar.. 

ALEXANDER,  JOSEPH  H. 

Electric   Railway    and    Welfare   ^Vork 

XVIII:     Oct.. 

allen'.'g.'  Y.                     .    ,  ,  j-    .• 
Standardization  of   Electrical  Indicating 
Instruments— For  Use  With  Radio  Ap- 
paratus   XVI :   Nov.. 

Automatic    Regulation    of    Electric    Arc 

Furnaces  XVII :    Sept., 

ALLCUTT.  C.  T. 

The  Foundations  of  Modern  Radio 

_ XVIII :    Apr.. 

APPLEGARTH.  C.  K. 

Manual  Starters  for  Small  Squirrel-Cage 

Induction  Motors  XVI:  Dec.. 

ARMSTRONG,  EDWIN  H. 

The  Regenerative  Circuit XVIII:  Apr.. 

ARMSTRONG.  M.  R. 

Enameling  in  the  Automobile  Industry.... 

XVIII :     Jan.. 

ARTZ,   W.   H. 

Electric   Paper   Machine   Drive    (E) 

XVIU :    Mar., 

ASHWORTH,  E.  A. 

Removing  and  Replacing  Railway  Motor 

Armature   Shafts XVI:    July. 

ASPINWALL,   L.   M. 
The    Bus.    the   Trackless   Trolley   or   the 
Trolley      Car      for     Light     Traction— 

Which?   XVH:    Oct.. 

AUSTIN.   B.   O. 

Foot  Control  of  Safety  Cars  as  Exemph- 
fied  by  the  Third  Avenue  Cars  in  New 

York   - XVII:   Oct.. 

AY  LES WORTH.  M.  H. 

Proposed  Reorganization  of  N.  E.   L.  A. 

XVU :     May. 

BABCOCK.  C.  W. 
Adjustable  Speed  Motors  and  Control  in 

Finishing  Plants   XVIU:   Nov.. 

BACHMAN.   R.   A. 

Motion— $30,000,000  Worth..XVIH  :  June. 
BALLARD.   R.  H. 
The  National   Electric   Light  Association 

Convention  at  Pasadena  (E) 

XVII :    May. 

Constructive  Central  Station  Suggestions 

(E)    - XVIII:   May, 

BARNHOLDT.  H.  L. 
The  Design  of  Large  Induction  Motors... 

XVI:    June. 

The    Propelling   Motors  of   the    U.    S.    S. 

Tennessee    XVIII:    June, 

BATSEL.   M.   C. 

Continuous   Wave   Radio   Receivers 

XVIU :     Apr.. 

BEHREND.   B.   A. 

The      Achievements      of      Benjamin      G. 
Lamme — Address    of    Presentation    of 

the  Edison  Medal _XVI :  June. 

Internal  Heating  of  Generator  Coils   (E) 

.„ XVII :     Sept.. 

BELL.  G.  G. 
The    Generating    System    of    the    West 

Penn  Power  Company XVIII:  May. 

BLATR,   HENRY   A. 
Outlook    for    the    Electric    Railway    In- 
dustry   (E)    _ XVIII:   Oct.. 

BOL/.E.  R.  A. 

Electrically-Heated  Metal  Pattern  Plates 

on   Molding   Machines XVI :    May, 

BOTT,   GEO.   K. 

Mounting  and  Care  of  Small   Ball   Bear- 
ings for  Maximum  Service _ 

XVII :    Aug.. 

BOWNE.  JR..  G.  D. 

Electrification    of    New    England    Textile 

Mills  lE)  _ XVIII:  Nov.. 

BOYCE,   W.    H. 
Things     to     Consider     in     Handling    the 

Public    XVI :   Oct.. 

BRACKETT.  Q.  A. 

Impu-se-Gap  Lightning  Arresters 

- XVI :    Feb., 

Radio   Arc  Transmitters XVIII:    Apr.. 

BRADLEY.  LUKE  C. 
The  Future  of  the  Birney  Safety  Car  (E) 

XVI :     Oct.. 

BRANN. ALBERT 
Chemistry  and  Chemical  Control  in  the 

Lamp   Industry XVI:    May. 

BRIES,  M.  M. 

Stroboscopic  Slip  Determination 

- XVII :    Apr.. 

BRIGHT.  GRAHAM 

Power  System  of  the  South  Philadelphia 

Works   XVI:   Apr.. 

BROOKS.  W.  G. 
Local  Associations  for  Organization  Bet- 
terment   XVI:   Oct.. 


BROOMALL,  A.  L. 
624  Preventing    the    Breakage    of    Armature 

Leads  on  Railway  Motors - 

XVI :    Oct., 

9'J       BRUSH.  M.  C. 

The   Transportation    Business — A   World 

Fundamental    (E)    XVIII:   Oct.. 

453        BUDD.   BRITTON  I. 

The  Development  of  Rapid  Transit  Lines 

(E)    XVIII:    Oct., 

BUFFE.  F.  G. 
494  Th6    Future    Outlook    for    Large    Urban 

Electric    Railways    (E) XVI:    Oct., 

397  The  Electric  Railway  and  the  Jitney  (E) 

_ XVIII :    Oct.. 

BUMP.  MILAN  R. 
120  The   Greatest    Development   in    Electrical 

History  (E)   XVII:  May, 

The  Utilities  Situation  (E)..XVIII:  May, 
532        BURG.   F.  A. 

Application  of  Steam  Condensers — 

153  Selection  of  Type XVII:  Dec.. 

Selection  of  Size XVIII :   Jan., 

BURT.  F.  R. 
6  Induction   Motor   Drive   for  Skip  Hoists 

:XVI :     Sept., 

BUTCHER,  C.  A. 
77           Installation    and  Maintenance   of    Auto- 
matic  Substations   XVIII:   June. 

CALLARD,  JR..  N.  H. 

311  The  Safety  Car _ XVI:   Oct.. 

CANDEE.  A.  H. 

Inspection    and    Maintenance    of    Direct- 
Current  Car  Control XVII:  Oct., 

443       CARLSEN.  C.  J. 

Electrical    Refrigeration XVII:    Nov., 

CARR,  WESLEY  G. 
Proposed  Changes  in  the  American  Pat- 

488  ent  System  XVI:  July. 

CAWTHON.  JR.,  JAS.  L. 

Electric  Furnace  Gray  Iron 

227  JCVin:   Sept.. 

CHAMBERS.  F.  C. 

Heat    Balance   Systems XVIII:    May. 

609        CHUBB.  L.  W. 

The  Foundations  of  Modern  Radio 

242  _ XVIII :     Apr.. 

CLARKE.   JR..  JOHN   A. 

The     Auxiliary     and     Lighting     Control 
Equipment  of  the  Chicago.  Milwaukee 

173  &   St.   Paul  Locomotives 

XVII :   June, 

158       CLAY.  N.  S. 

Bakelite  Micarta  Airplane  Propellers 

XVI :   Nov.. 

251       COAXES,  W.  A. 

European    High-Voltage    Switch-Gear 

261  - XVI :     June. 

COLE.   A.   B. 

Electric  Railway  Freight  Haulage 

136 JCVI:    Oct., 

COLEMAN,  H.   C. 
Electrical     Equipment     Used     on     Sub- 
marines   XVI:  July. 

235  The  Electrical   Equipment  for  the  "Lyn- 

donia"  Stabilizer  XVIU:    Aug., 

362        COLLIER.  B.  G. 

An   Apiieal  to  Manufacturers  and  Deal- 
ers (E)  _ XVIII:  Oct.. 

175       COOK.  C.  S. 

An  8a-Mile  Central  Station  Bus  (E) 

XVm :     May. 

440       COOK.  W.  W. 

Inspection  and  Overhauling  of  City  and 

Interurban  Cars  _ XVI:  Dec.. 

229        COPLEY.  A.  W. 

Short-Circuit    Calculations    (E) 

XVI :    Aug.. 

The     Electric     Power     Supply     for     the 
322  Puget    Sound    Lines    of    the    Chicago. 

Milwaukee  &  St.  Paul   Railroad 

XVII :    Jan., 

486  Regulation     and     Inductive     Effects     in 

Single-Phase    Railway    Circuits _ 

XVII :   Aug., 

433  Parallel  Operation  of  Gas  Engine  Driven 

Generators    XVII:    Sept.. 

CORNELIUS.  M. 
52            The  Control   Equipment   for  the  Propell- 
142                ing    Machinery    of    the    U.    S.    S.    Ten- 
nessee     XVIII:    June. 

CRICHTON.  LESLIE  N. 
419  Testing  Insulators  in   Factory  and  Field 

XVn  :    Nov.. 

GRIDDLE.  E.  B. 

198  The  Irrigation  of  the  Desert 

XVII :    May. 

CROSS.  C.  M. 

165  Expanding   Bronze   Bearings 

XVII :     Oct., 

CULKINS.  C.  W. 
,.,,  The     Best     Plan     for     Operating     Street 

'-"  Railways    (E)    XVII:    Oct.. 

CUNNINGHAM.  A.  H. 
Methods  of  Computing  Ifachinery  Foan- 
464  dations  _ XVII:    Sept., 


CURTIN.  J.  M. 

Post-War  Industrial  Reconversion  (E).... 
_...XVI :    Jan.. 

Starters  for  Small  Induction  Motors  (E) 
_ _...XVI :   Dec. 

The  Electrification  of  Industry   (E) 

XVIII :     Jan.. 

DANA.  EDWARD 

The  Problem  of  Mass  Transportation  (E) 

—XVIII :     Oct.. 

DANN.  WALTER  M. 

Transformer  Equipment  for  the  Chicago. 

Milwaukee  &  St.  Paul  Railroad 

XVII :     Jan.. 

DARLINGTON.  F. 

Water    Powers    (E) XVI:    May. 

DAVIS.  CHAS.   W. 

Allowable  Working  Stresses  in  High- 
Voltage   Electric   Cables. _ 

„ XVn  :    July. 

DAVIS.  H.  P. 

Munition  Work  in  PitUburgh    (E) 

„_ XVI :    Jan.. 

Radio— Its  Future    (E) XVIII:    Apr.. 

DAVIS,  L.  J. 

Dad,  the  Inspector,  on  Co-operation 

XVI :    Jan.. 

DAY.  HENRY  S. 

Methods  of  Hiring  and  Training  Men 
Used    by    the    Mechanical    Department 

of   the  Kansas  City  Railways 

_...XVII :     Oct.. 

DEAN,  J.  S. 

Railway   Motor  Testing XVI:   Jan.. 

Armature  Testing  - XVI:   Feb.. 

Testing  Railway  Fields XVI:  Mar.. 

Testing  Assembled  Railway  Motors 

XVI :    Apr.. 

Railway   Motor  Bearings. XVI:    Oct.. 

Does  it  Pay  to  Dip  and  Bake  Arma- 
tures   XVI :  Oct.. 

Shop  Organization  .- XVI:   Nov.. 

Systematic  Insiiection  of  Car  Equip- 
ments   XVI:  Dec. 

Repairing  Loose  Housings  on  Split 
Frame  Motors   XVII:   Jan.. 

Broken  Leads  in  Armature  Windings... 
XVII :    Feb.. 

Key   for  Railway  Equipment  Repairs 

XVII:    Mar.. 

Armature  Troubles  Resulting  from 
Broken    Motor    Leads. XVII:    May. 

Field     Winding    Diagrams     for    Railway 

Motors     

XVII:  Juno.   272:  Aug..  358:  Sei>l.. 

Severe  Winter  Operating  Conditions — 
Practical  Methods  for  Minimizing  Pos- 
sible Troubles  XVII:   Oct., 

Armature  Winding  Diagrams  for  Rail- 
way Motors    - XVII:    Oct.. 

Checking  Armature  and  Axle  Bearing 
Wear XVII:   Dec, 

Armature  Record  Tags XVIII:  Mar.. 

First   Aid   for   Electrical   Injury 

XVIII :   Apr.. 

Tinning  Malleable  Iron  Bearing  Sheila... 
XVIII :    Aug.. 

The  Assembly  of  Complete  Sets  of  Com- 
mutator Segments  XVIII:  Sept.. 

Side  Wear  of  Carbon  Brushes  on  Venti- 
lated   Railway   Motors XVIII:    Oct.. 

Electric  Welding  as  a  Factor  in  Re- 
clamation     XVIII:    Oct., 

DeCAMP,  R.  E. 

Autotransformer  Motor  Starters 

JCVn :    Jan., 

DEESZ.  LOUIS  A. 

Reducing     Mechanical     Difficulties     with 

Motor-Driven     Applicationa 

XVIII :  'Sept.. 

DENMAN.  E.  W. 

The  Development  of  Fan  Motor  Wind- 
ings    XVI:    June. 

DENNINGTON.   A.   R. 

Mazda  C  Lamps  for  Motion  Picture  Pro- 
jection    XVI :    May. 

DICK.  W.  A. 

Regulation  of   Automotive    Generators... 

XVI :    Apr., 

DOBSON.  J.  V. 

The  Handling   of   Cooper XVIII:    Feb.. 

DOOLEY.  C.  R. 

The  Student  Army   Training  Corps   (E) 

XVII:    Feb.. 

DORFMAN.  L. 

A  Problem  in  Three-Wire  Distribution 
from  Rotary  Converters XVI:   Nov.. 

The  Choice  of  Instrument  Transformers 

_..JCVn :   Aug., 

DOUB.  C.  L. 

Safely   Car   Operating   Results 

xvni :    Oct.. 

DOUGHERTY.  J.  J. 
Steam  for  Extinguishing  Fires  in  Turbo- 
Generators  XVI :   May, 


THE  ELECTRIC  JOURNAL 


13 


May, 


nRABELLE.  J.  M. 

Heat  Balance   Systems XVIII 

^KJ^ttfrC^u^st?.   (E,^      XVI:  Oct     410 

^ru^;c;'r%f ''."''.^' ..-'  ...xviTp -^ 

Wasting  Capital  in  Bus  Competit: 


^  Thri^'d«"tr"l  Field  of  the  West  Perm 

Power  Company  XVlll' 

GADSDEN 


May,  189 


May.  163 
(E) 
XVIII:     Oct..  448 


A.  M. 


'DUDLEY,  rx.  ..i.  .  ,   „  .  ..        „f 

Eeversing   the  Direction  of   Rotation   of 

Sincle-Phase  Motors  .XVI :  Feb.. 

Storage  Batteries 

(E)    

DUDLEY.  S.  W.  .     ^      ,. 

Air  Brakes  in  Electric  Traction.......^^^.. 

DUFF.  SAMUEL  E. 
Enpineers  Should  Study  Cost  Accounting 

(El    

DWIGHT,  H.  B 


XVII:  Jan., 


Resistance  and  Reactance  of  Commercial 
Steel  Conductors  .......XVI:  Jan., 

Reactance  Values  for  RectanKular  Con- 
ductors       AVl:   June,  . 

The  Electrical  Characteristics  of  Trans- 
mission Conductors  -^'^^  ^'^^1^?°^^^'. 

eastonV  williaS  H. 

Electricity  in  the  World's  Largest  Hotel 


Home' the  Facts  (E)   XVHI:  Oct..  427 
GELZER.  JOHN  .        ^      o     .u 

'^'"  ■^'""'^.'."''"''.''.'..'."...XVin"     Nov::  491 
GERHARDT.'  R.   B.  ,       ,„  x     i,    ii„i 

Electrical    Equipment    for    GO-Inch    Uni- 

versal  Plate   Mill XVII:    Sept„  363 

ectrical  Developments  in  the  Iron  and 

Steel  Industry   (E) XVHI:   Sept..  383 

GIBBS.  J.   B.  „         , 

Three-Phase   to   Two-Phase  Transforma- 

tion   XVI:   Mar.,  lui 

GIBSON,  C.   B. 

The     Manufacture    of    Ferro-Alloys    in 

Electric  Furnaces  ^^.XVI :  Sept..  366 

The  Regulation  of  Electric  Furnace|^(E)   ^^^ 


Electri 


..XVI:    July,  288 


EATON,    G.    M.      , 

Decreased  Operating   (jost; 


■ith   Helical 
XVI:   Oct..  430 
M^cal^MaVntenance  rf   MiH^I^t.  ^^^ 

^^D™e?ip«on^of    a    Uni-Wave    Signaling 

System   for   Arc   Transmaters^......^.j..^..  ^^^ 

^*Motor-Dr°en  Plate  MiIls....XVIII :  Sept.,  414 
EGLIN.  WM.  0.  L.      ^     ^^     .         ,„. 

Central   Station   Profit    Sharmg^^CE)^.^^.   ^^^ 

'^l;'^r^har*'act"ristics     of     T^^nBtormer     ^^ 

EVANS.  ROBERT 'd. 

Analytical   Solution   of   Networks....^^.^..  ^^^ 

The  Electric  Furnace  as  a  Central  Sta- 
tion Load  with  Particular  Reference 
to  Phase-Balancing  Systems^.^.^....-^.^.^.^..  ^„^ 

Transmission  ■■'Line      Circuit     Constants 

and  Resonance  XVIII:  July.  J»b 

Transmission  Line  and  Tr^nsforme^s^^-.  ^^^ 

Circie  ■  Dra'ir'a:ms  "S'r  ■TransmUsion    Sys-  ^^^ 

terns   -^  ■ 

^^T^h^'^fnsutti^n    of    Distribution    Tr^ns- 

formers  Ji.vi.   Di»j. 

PBCHHEIMER.  C.  J.  ^  ,    ,     ,     i„ 

Embedded      Temperature      detectors      in 

Large  Generators  XVII.  Sept..  41" 

FERRIS.  R.  E.  ..         (3.^ 

The    Axle-Generator    Regenerating    bys- 

tem   Used  on  the  Chicago.  Milwaukee 

&   St.  Paul   Paisenger   Lacomotives.    .. 

XVII;    Feb..     4b 

Auxiliary    Rotating    Apparatus    for    the 
Chicag':,,  Milwaukee  &   St    Paul  Loc^  ^^^ 

motives    ;         ;k.     " '^   __.„7 

Voltage      Relations 


GIBSON.   JOHN  J.  .  „       , 

Present  Trend  of  Electrical  Development 

(E)    XVIII:  Jan.. 

GILCHREST.  C.  R.  ,         ,   ..   .t:  .„ 

Tie     Line     Application     for  „i?aHftion 

Feeder  Regulators XVII :  Nov., 

GILCHREST.  G.  I. 

Application  of  Theory  and  Practice  to 
the  Design  of  Transmission  Line  Insu- 
lators   XVI:   Jan.. 

GILCHRIST.  JOHN  F. 

The  Sale  of  Stock  to  Customer 


"fI;^;  R^e^r'sing  Mill  Drive  in^thi.  Coun-  ^^^ 

«s^'?;o!-i:Ei::t:icMou,rs^^^..,3, 

'iS-f:."'"55vi^sSs,2 

"Ele^trica'liySriven    Plato    Mill,    of    the 

Brier  Hill  Steel  Company.  XVI:  May.  188 

HANKER.  F.  C.  wirr.  T.ilv    "91 

Power  Transmission   (E)       XVIII:  July.  -Ji 

HARVEY,  DEAN  .      „     ,     „ 

Methods  of  Testing  for  H»rdne^«|-..j^^^-  ,j^ 

"swUching^and   Protection   of   Tra„smi»- 

sion   Circuits  ^,  XVII.  May. 

178;     June.     263:     Nov.,     621:     Dec, 

HECKER.  G.  C.  .  ,  oc 

Changing   Railway    Substations   from   26 

to  60  Cycle XVIII:  Dec. 

HECKMAN.  A.  ,     -      ii    t™„^ 

HENDERSON 
Temperature 


555 


539 


GILMAN.  R.   E.  ,    ,u      tt     «     '5 

The    Main    Generators    of    the    U.    h.    » 

Tennessee  XVIII:  June 

GILLELAND.  W.  H. 

Methods  of  Computing  Machinery  Foun- 
dati  " 

GILSON.   B.  W 


..XVII:   Sept.. 


Indicators    for    Alterniitors 

XVI:     May.  193 

Ground;;.!    Neutral    on    Alternatlng-Cur- 

rent  Generator.  y  w.X^^'   ^"f.;  ' 

Eddy   Current   Losses  and  Temperature. 

nf   Rtntor   Coils - XVII:    Sept..  418 

HERMANN.  R.  L.  ti     i     » 

Result  of  Twelve  Years'  Heavy  Haulage 
on   the   Single-Phase  Elcctrincalion   of 
the  Grand  Trunk  ^'^"^"^^{r'oci.  480 
(E) XVI:  June:  233 


The  Growth  and  the  Accomplishments  of 
the  Assoc,  of  I.  &  S.  E.  _K_(E).. 


..XVII:     Sept..  359 


Generator  to  the 

"but"  oT  Phale XVIII ;    Sept.. 

GOODING.  R.  F. 

Substation    Short-Circuits XVI ;    Feb., 

GOODWIN.  W.  C. 

Electric  Controllers  fo 


61 


le  Hoists 

XVII:    Mar..  119 

The  "Con'troi'o'f "  the  Secondaries  of  the 
Main  Propulsion  Motors  of  the  US- 
S.  Tennessee  XVIII:  June.  -78 

°  T'tfR^itL  of  Flywheel  Effect  to  Hunt- 
ing in  Synchronous  Motor^.^.^.^.  . .■■^•^-^-     ^^ 

^  nil^Poier^Stations    of    the    Duauesne 

Light  Company  XVIH :  May.  183 

GRIFFITH.  F.  T.  .         . 

The  Water  Power  Situation   W.- 


HERR.  E.  M. 

Benjamin  G.  Lan 

"n^w  SouTh  Philadelphia  Plant  of  The 
Westinghouse  Electric  &  Mfg.  Com- 
pany    .vvi.    «i»r.. 

HERSHBERGER.  D.  C. 

Comiinrison    of    Low-Speed     and    High- 
speed Interurban  Freight  '^07"°'^™'  435 

"lomrF^"atS«f  of  the  Cottrell  Plant   at 

the  Hayden   Smelter... XVIH :  July.  304 

HERSHEY.  Q.  W.  .0.0 „ 

Single-Phase  in  Thirteen  Year.  Success- 
ful Operation  on  the  Erie.. 


..XVII;  Oct..  460 


W.  H. 


..XVII;    May.  177 


GRISSINGER.   0.  G. 
High-Speed    Circuit   Breakers. 


XVIII:  Feb.. 


HEULINGS.  JR ■    „,^     „  „  ,„. 

The  Standard  Type,  of  Clty^Car.  (EK...  ^^^ 

HIBBEN.  SAMUEL  G.  „     .„    „.,. 

""^  ""''..''!'^''.V''.'.^"'.""...TVni!"Nov..  615 

The  Value  of  Association  of  the  Mechan- 

'"'''...°.':':".'".'"'.'..l.^!".'xvin^^ 

HILD.  F.  W.  ^     .  ,  ,     ,p. 

Hold  Fast  to  the  Fundamentals  <b) 


Machines 
FINLAY.  W, 


32 


S..  JR 


GROUP.  J.  C.  ,.         r  ,    Ai 

Switchboard   Meter   Connections   for   Al- 
ternating-Currents  Circuits: 

I-lntroduction    ., XVII;   Jan., 

II_Two-Phase   Circuits XVII :    Feb., 

Ill— Three-Phase.  Three-Wir|^^rcuits^... 

IV::^Siigie-Phas'e  Wattmeters  on  Three- 
Phase.    Three-Wire    Circuits 


HIPPLE.  J.  M. 


XVI:    Oct..  412 

of    Motor 


Sixty    Thousand    Kw    Turbine-Generator 
""installation  at  the  T4th  Street  Station 
of     the     Interborough     RaP'^^j^"^^"^'^*  17.^ 

FITZGERALD,  THOMAS 
The  Problem  of  Street  Con|estmn.. .......  ^^^ 

^^fleI^lri:e'.o:'To..doI^^^^ 

M°n 'Shie'  and  "Turtine-lpid    Con- 
trol for  the  U.  S.  S.  Tennessee....^_^..  ^^^ 

^^i';iii^?i^ncing^-the^f--,,3 


131 


XVII:    Apr 
V-Threelphase.   Four-Wire  ^C^rcuits^^^.  ^^^ 

VI^Sixlpi.ase""circuiti::Zxvn;    June,  261 
VII  and  VIII— Measuring  Reactive  Volt- 
'\mneres    in    Three-Phase.    Three-Wire 

^M™cuk3  XVII:  July.  281  Aug..  355 

IX— Synchronizing   with    Lamps. 


..XVII:    Nov. 
^^Synchronizing  with   Synchronoscopes 


536 


..XVII:    Dec.  567 


Steam'  Turbines  for  Mechanical  Drive 


GRUHL.  EDWIN  „  .  , 

Inherent   Defects   and   Future   Sphere  of 

Usefulness  of  Electric  Traction   (EK-- 

GUILFORD.  C.  T. 

Silk  Throwing  and  Electric  Dri%v~ 


^Rating""'"  .  XVn:M.y.  20s 

Use"«'nd  Abuse  of  E'^trlc  Mt^ors.......^..  ^^^ 

HOGAN.  JOHN  V.  L.  _  .^vttt.    Anr     116 

The  Heterodyne  Receiver...XVIII .   Apr.,  no 

HOOPER,  S.  C. 

The   Lafayette  Radio  Station^......-^^^--  jj^ 

HITMPIIREY.  GEO.  S. 

The    Transmission    System    of   the   West 

Penn  Power  Company XVIII.   May.  io» 

HUTCHINSON.  W.  M.  .       .  „  . 

^^hi^lef:'^^'."'^..°^.:^^^"'S^"-' 

'^^llf  Jjatro^fr&c  Llght^  Association 

JACKSON,  R.  P. 

Electrical   Insulating   Materiale. 


..XVin:  May.  167 


XVII:    Apr.. 

The  Dual  "Drive  Units XVIII:  Feb.. 

^TtXp^Sa'^tion     of     Adjustable    Speed 
Main   Drives  in 


XVnl:    Nov..  512 


48       HAGEMAN.  A.  M. 


^C^ntWtaJTon  Power  for^Te^^ile  Mills  ^^^ 

^Si^^^AJiS^tica.    solution    of 

Networks  ■*■'" 

FRANKENBERG,  ARTHUR  K 

Increasing     the      Load     witl 

Lamps   


wiei...=.i:r    ..iid   Chemical   Control   in  the 
"L:-;mp  industry  XVI;  May.  1 

"performance  of   Motor-Generator   Sets^ 
For    the    Chicago.    Milwaukee    &     bt. 

Paul  Railway  .-.^ XVI:  Feb., 

Voltage     Regulating     Systems     of     Syn- 
chronous  Converters   XVIII:  Jeb.. 

Stray    Losses    in    60-Cycle    Synchronous 

Converters    XVIU  .    July. 

Aug..  350       HALL.  DAVID  „  ^     ,       ,i,„ 

3000   Volt  Motor-Generator   Sets  for  the 

Chicago,  Milwaukee   &   St.^Paul  Ran- 


XVI:  Aug..  326 
Industrial  Adaptation  '" f^^y^'Vov.'.  469 
High-Si>eed  Photography   (E)--j;    p-'  507 

The  6sciiiogri;>h"(iB)::::::::::"xv"=  Dec.  539 


' Impfovement's  in  ConUctor  TVPe'.  ol:  In- 
dustrial  Controllers XVI-    Nov.. 

Manual     Starters     for     Small     Souirrel- 


1      Portable 
XVI:   May.  216 


"Cage  Induction  Motors  .XVI:  Dec 

Autotransformer  Motor  Starrer...........     3^ 

Current  "Limit"A'c'cSeratio'n  ^o^jElec^nc     ^^ 

Di"ect-clr,^nt-Cr«ne--Cont™^W^ 


14 


THE  ELECTRIC  JOURNAL 


JEFFRIES,  E.  S. 

the   Cost    of   Interruptions   of   Power   to 

Steel  Mills  ..._ XVII:  Sept.,  371 

The  Association  of  Iron  and  Steel  Elec- 
trical  Engineers    (E) XVIII:   Sept.,   381 

JOHNSON,   H.  H. 

Encourage    Young    Engineers    to    Enter 

Railway  Organizations  (E)  

,„   XVIII:  Oct.,  449 

JOHNSON,  J.  F. 

Notes  on   Large   Steam   Turbine  Design 

.      XVI :    Jan.,     S3 

JOHNSON,  OTIS  L. 

Notes  on  Industrial  Lighting 

,„•■■■" XVII :    May,  198 

JOHNSTON,  H.  H. 

Maintenance  of  Fuse  Boxes  for  Railway 

Service  XVI:  Sept.,  389 

Remotely     Controlled     Electric     Locomo- 
tives in  the  By-Product  Coke  Industry 

..........  XVn :     Feb.,     49 

Industrial     Type    Locomotives     in     Steel 

Mill  Operations  XVII:   Sept     392 

JUNGK,  H.  G.  ^ 

Heating  Passenger  Coaches   on  the  Chi- 
cago,  Milwaukee   &   St.   Paul   Railroad 

keal^Vphiup  j: ^^^^-  *"«'■•  ^-* 

The    Outloolt    for    the    Next    Five    Years 

(E)    XVIII-    Oct     43'; 

KEENEY,   ROBERT  M. 

Use  of  Electricity  in  Metallurgical   Pro- 

keith"h.-l; - ^^"=  M^^-  ^o" 

Automatic  Push   Button   Elevators 

kelly:j;f; ^"^^'  ^^'-^ "^ 

Electrical   Development   in   the  Iron  and 
fi'-?k^,"^Z''^   <E) '^Vl:   Sept.,  358 


KEMPTON.  W.  H. 

Moulded  Insulation XVI:  Mar.,     84 

Designing   Moulded   Insulation 

kennard;  R. ^^^-    -^P"^'  '5- 

The    Manufacture    of    Copper    Wire    and 

kinIa?S^c:  w. ^^''■-  A"«^-  ^" 

Variable  Speed  Induction  Motor  Sets. 


KINTNER.  S.  M; ^'^'"•'    ^^P'-  5»= 

Epoch  Making  Radio  Inventions  of  Fes- 

Ki^TlrmG.  r;t: - ^^"=  ^p-- '" 

Electrically  Operated  Grain  Car  Unload- 

KIRKER.  h:  i; XVin  July,  301 

Purchased  Power  for  Traction   (E).. 


KIRKPATRICK,  TrP.' 


■XVII:  Oct.,  436 


The  Electrical  Equipment  for  the  "Lyn- 

kline^lIerI't^a '''''"=  ^•"^-  '** 

Application  of  ■Hieory  and  Practice  to 
the  Design  of  Transmission  Line  Insu- 
lators      WT       T 

KRAMER.  ELBERT •''"'■•       ^ 

A"'°P;a«'<'  Electric  Enameling  Oven   In- 


Sa^n'Fr.^V  ^°^'^""'  Cornice     Works, 
LABBERTON,  J.  JS. ^VUZ  :  Mar.,     82 

^°nJ;i  ^°'"ii  ."^    D'PP'nE    and    Baking 
Railway    Motors    .  TVTT.    A-t      ..ci, 

LAMBERT,  M.  B.       a VII:   Oct..  491 

Maintenance' of  Railway  Equipment  (E) 
ConSi^cti^iltectric  Railv^a^^k"^)   '" 
The^  PrSiem    of -the    Eiectri^^i,^3  ''" 

LAMME.  BENJAMIN  G '^^'"'  ''*"'       ^ 

•^  ESrn  lEfedtf''--  °'^  ^--tation  of 
Preparation   of  Technical   Papers  ' 

Ventilat^n^  and-T?e;Jj  ,■  ^rjl^i     '' 
in   Large  Turbogenerators        """'^"'^ 

^^^^^im^^-d^  ^^l,^;  345 

Data  and  Tests  o^iooooljJJJI^^Apn.  Ho 

ond  Alternator  ^XVmVl^t.  132 

LEGG,  J.  w.     - ^^"'-  ^^^'-  3*- 

'"ca,^e°;r-    ^-'''-E-Posure,    High-Speed 

T,,       >.         „ XVI:    Dec..  509 

The   New  Portable   Oscillograph    as   An. 

LEHR    E.  E                ""'  ^-^  ^-^I  "Dt":  563 
The  Step   Induction   Regulator 

,       XVlii'Nov.,  510 

LEONHAUSER,  H.  A. 

Shop  Facilities  for  Maintenance  of  Rail- 
way Equipment  XVIII:  Oct.,  464 

LEWIS.  WARREN  B. 
Motors  for  Textile  Finishing  Plants 

XVIII :    Nov.,  504 


LINCOLN,  PAUL  M. 
The     Thermal     Storage     Demand     Watt- 
meter   XVII:  June,  253 

LITTLE.  D.  G. 
Continuous  Wave  Radio   Communication 

XVIII :    Apr.,  124 

LLOYD,  C.  F. 

Value  of  Automatic  Railway  Sub-sta- 
tions to   Central   Stations    (E) 

LodMIS;- ALBERT- a '''"  =    *'"''•  "' 

Lighting  Sets  on  the  U.  S.  S.  Tennessee 

^  ■  ■■•■ XVIII:    June,  271 

Condensing  Equipment  and  Oil  Cooling 
System  for  the  U.  S.  S.   Tennessee 

lynch:- tVd: ^^"^^  •'""^- "' 

Manufacture  of  Six  Inch  High  Explosive 

Shells  for  the  United  States  Army 

LYNC-h:  E.-JD. -.XVI:    Jan..     17 

Haul  Freight  the  Electric  Way  by  Use 
of   Standard   Freight  Equipment 

LYNN,  A.  M. 

Moderation  Must  Govern  Future  Munici- 
pal Action    (E) XVI:  Oct.,  416 

The  Central  Station  Company  as  a  Com- 
munity Asset  XVIII-  Mav    167 

MacDONALD,  H.   G. 

Large   Capacity   Circuit   Breakers 

,  ■;  -" XVI :   June,  261 

Inverted  Contact  Circuit  Breakers.  . 

XVII:  Feb.,     78 

MacMURCHY,  J.  A. 

Lighting  Sets  on  the  tJ.  S.  S.  Tennessee 

man-n-i-ng-.-w-.--t: "^"'^  ^""'-  "' 

The  Construction  of  the  "Lyndonia"  Sta- 

MANTeI":  E-.-W. ''^"'--   ^"^-  ''' 

Electricity   in   Celluloid  Manufacture 

MARbis:  p;-l: ^^'=  *•"•  «" 

The  Electric  Equipment  and  Control  of 
the  Chicago.  Milwaukee  &  St.  Paul 
Locomotives  YVTT  ■   Tnno    o^r, 

MATTMAN,  E. 

Mechanical  Construction  of  Water  Wheel 

Driven  Alternators  XVIII  ■  Jan       "5 

McCALL,  JOSEPH  B.  "'.Jan.,     .5 

Sound  Central  Station  Policies  (E) 

mccloskey;  f;-w: ''"'''■  '"''■  "' 

Overloads  in  Railway  Motors 

„-.  ■; ■■■-•■; XVI:    -Oct.-!  457 

Maintenance  of  Railway  Equipment 

McCLTOK-r-c; '''''■  °'='-  *'' 

Ventilated   Motors    for   Hoist  Work    (E) 

Mcc-6n-S6n-.-w.--g-. '''^-  ^°"-  '"' 

Some  Labor  Conditions  in  Foreign  Coun- 

McCORKLE.  jXMi-S -W.- ^^"'=  ""•  '"' 

Locating  and  Repairing  Armature  Wind- 
ing Troubles   _,  XVT  •  Mnv    •?1t\ 

McCORMACK.   D.  J.      '^^'  ^"' 

Hydraulic   Reaction   Turbines 

McC^idcS:  LEON - ^^-     '^■-  "" 

The   Protection   of  Iron   from    Corrosion 

mci>;™e;-a;-h; ^'"''-  ^"'^-  =«' 

Pooling  Our  Resources    (E) 

.....    xvi :     -Apr.-;  US' 

Ihirty  Years  of  Service  to  Electrical  In- 
dustry   (E)   .... XVI:   Sept.,  359 

Making    Electrical    Connections    (E) 

„ -.^v- -1 V XVII:    Jan.!       2' 

Some  Figures  Electrical   (E) 

„  • .; Vt;",-;v ^^''^  '■   J""^'  233 

Railway   Utilities   Approaching   Stability 

fE)    ..._ XVin:   Feb.,     47 

The  Pittsburgh    Power   Zone   (E) 

Mckinley;  JOSEPH  ^"'^  """•"' 

Power    Requirements    in    the    Pittsburgh 

McLure"l.-c; ^^™=  "»^'  ''' 

Excavating  with  Electric  Power  in  the 
Miami   Conservancy  District 

MEAD;-DAmiL-w; ^"^"^    ^''^■-  ''' 

Water   Power   Developments 

meyer: -s;-  r: ^^"^  ^"'^■^-  ^'* 

Mounting  and  Maintenance   of   Car  Re- 

..^i^'ors  XVI:  June,  269 

Maintenance  of  Magnet  Valves 

.  -•.—■: ■■■.;. Xvi:     Aug.-;  353 

Lubrication    of    Control    Apparatus.. 

„-:v-v ■:■- XVI :     Oct..  468 

Method    of    Connecting    Car    Wiring    to 

Motor   Leads    and   Ground 

„  V: ~ ; XVII:   -Apr!;  168 

Voltage    Testing    of    Control    Equii)ment 

XVII :     July.   318 

Multiple-Unit  Control  Equipment  for  the 
Cleveland  Interurban  Railwav  Com- 
pany   XVII:   Oct.,  464 


Types    of    Transition    Used    to    Obtain 

Series-Parallel  Operation.JCVIII :  Jan.,     46 
Stopping    a    Car    by    Braking    with    the 

Motors   XVIII:   July,  334 

General   Information  on  Grid  Resistance 

Design  for  the  Operating  Man 

XVIII :    Nov..  .i56 

MILLS.  C.  B. 
The  Nerve  Center  of  the  Battleship  Ten- 
nessee    XVIII:   June,  288 

MOON,   F.   L. 

Direct-Current    Motors     for    Crane    and 

Hoist   Work   XVII:    Nov.,   532 

MOORE.  EDWARD  T. 

Secondary  Conductors  for  Electric  Fur- 
naces     XVII :    Sept.,  422 

MOORE,  W.  E. 

Electric   Furnaces  for  Steel   Foundries — 

With   Historical   Introduction. 

XVI :     Sept.,  360 

MORGAN,  C.  E. 
Electric  Railway  Passenger  and  Freight 

Transportation    XVI:    Oct..  422 

MORGAN.   D.   W.  R. 

Cleaning   Surface   Condenser   Tubes 

XVIII :     July.  313 

MORTIMER.  J.  D. 

Immediate     Economic     Aspects     of     the 

Electric    Supply   Industry    (E) 

XVI :    May.  163 

MOSS,   C.   M.   McL. 

Substation  Switching  Equipment  of  the 
Chicago,  Milwaukee  &  St.  Paul  Rail- 
road   XVII:  Jan.,     15 

MOULTROP,  I.  E. 
The    Technical    Work    of    the    .Vational 

Electric  Light  Association    (E) 

XVIII :     May.  161 

MULLANEY.  BERNARD  J. 

Illinois    Pioneering    in    Public    Relations 

(E)    XVIII:   Oct..  445 

MURPHINE,  THOMAS  F. 

Municipal  Railway  Operation   at  Seattle 

XVI :     Oct.,  428 

MURRAY,  W.  S. 
The    Primaries    of    Today    the    Second- 
aries  of    Tomorrow    (E) 

XVI :    May,  168 

NESBIT.  WM. 

Electrical    Characteristics    of    Transmis- 
sion Circuits. 
I— Resistance     Inductance        XVI:    July,  279 

II— Reactance  XVI:  Aug.,  314 

III — Quick    Estimating   Tables 

XVI :     Sept.,  386 

IV— Corona  Effects  XVI:  Nov.,  486 

V— Speed  of  Electrical  Propagation — 
Paralleling   Circuits — Heating  of   Bare 

Conductors  XVI:   Dec,  615 

VI — Frequency  and  Voltage  Determina- 
tions   XVII:  Jan.,     21 

VII— Performance  of  Short  Transmis- 
sion   Lines    (Capacitance    Not    Taken 

Into  Account)   XVII:  Feb..     66 

VIII — Graphical   Solution  of  Long  Lines 

- XVII :    Mar.,  104 

IX — Convergent  Series  Solution  of  Long 

Lines  _.XVII :  Apr.,  146 

X — A  Review  of  Hyperbolic  Trigonom- 
etry    XVII:   June.  267 

XI — Solution  of  Long  Lines  by  Hyper- 
bolic  Functions   XVII:    July.  299 

XII    and    XIII— Comparison    of    Various 

Methods  of  Solving  Long  Lines 

XVII:  Aug.,  350:  Nov..  527 

XrV — Heating  Limits  for  Cables 

XVII :     Dec.  676 

XV — Synchronous      Motors      and      Con- 
densers     for      Power-factor      Improve- 
ment    XVIII:   Aug..  365 

XVI— Phase  Modifiers  for  Voltage  Con- 
trol  XVIII:   Dec.  642 

NEWBURY.  F.  D. 

A  Record  of  Large  Turbogenerator  Ar- 
mature   Bre.ikdowns XVII:     Aug..  362 

Embedded      Temperature      Detectors      in 

Large   Generators XVII:    Sept.,  410 

Regulation    by    Synchronous    Converters 

(E) XVIH:   Feb.,     47 

Stray  Losses  in  Converters   (E) 

XVIII :     July.  291 

>'EWTON.  R.  H. 

Commutator     Brushes     for    Synchronous 

Converters   XVIII:    Feb..     61 

Commutator    Maintenance    of     Synchro- 
nous Converters  XVIII:  Mar.,  106 

NUTTING,  P.  G. 

Research    and    Manufacturing    (E)  . 

■ XVII :    Apr..  127 

NYMAN.  A. 

A  High-Frequency  Generator  for  Air- 
plane Wireless  Telegraph    Sets 

„ - XVI:    Apr.,  140 

Power-Factor   m   Polyphase   Circuits 

XVIII:     Jan.,     20 

O'BRIEN.  H.  F. 

Electricity  in  Motion  Picture  Studios 

XVII:    May,   223 

O'BRIEN,  M. 

Construction  of  Semi-Steel.  Front-En- 
trance Side-Exit  Cars XVIII:  Oct..  468 


THE  ELECTRIC  JOURNAL 


15 


GETTING,  O.  W.  A. 

Characteristics  of  Startlnp:  and  LiRhtinff 

Batteries  of  the  Lead  Acid  Type 

XVI :    All!-..  134 

OLNHAUSEN.  J.  E. 

Electricity  in  the  Textile  Industry   (E).... 

XVtll :   Nov..  485 

OTTO.  OSCAR 

Manufacturing     Scheme     of     the     South 

Philadelphia  Works XVI:  Apr..  122 

OWENS.   E.   W. 

Efficiency  of  Adjustable  Speed  Motors... 

XVIII:     Jan..     11 

PALMER.  E.  A. 

Service  with  the  Safety  Type  Car 

_ XVI :     Oct..  426 

PALMER.  L.  H. 

The  Future  of  the  Autobus  as  it  Affects 

the   Electric   Railway    (E) 

XVII:   Oct..  430 

PARDEE.  JOHN  H. 

The  Street  Railway   Situation   (E) 

XVI :     Oct..  405 

The  Electric   Railway   Situation    (E) 

XVII :     Oct..  429 

The    Problems    of    the    Street    Railways 

(E)    XVIII:    Oct..  432 

PARKS.  J.  B. 
Modernized  Plant  of  Prudential  Worsted 

Co XVIII:    Nov..  489 

PATTISON.  HUGH 

The  Logical  Unit  for  Comparinij  Repair 
Costs     of     Electric     Locomotives     and 

Cars   XVII:    Oct..  475 

PETERS,  J.  P. 

Transformers  and  Connections  to  Elec- 
tric Furnaces  XVI:  Sept..  397 

Tertiary  Windings  in  Transformers — 
Their  Effects  on  Short-Circuit  Cur- 
rents    XVI:   Nov..  477 

Static  Frequency  Doublers..XVIII :   Apr..  122 
PETERSON.  A.  J.  A. 

Installation  of  Switching  Equipment  for 

Synchronous   Converter    Substations 

XVIII :     July.  329 

PETTY.  D.  M. 

The  Association  of  Iron  and  Steel  Elec- 
trical   Engineers    (E) XVI:    Sept..  357 

PIERCE.  R.  T. 

The  Stability  Indicator XVIII:  June.  280 

PILLING.  N.  B. 

Copper — A  Delicate  Material 

XVII:     Aug..  320 

PONSONBY.  W.  H. 

Testing  Railway  Control  Equipment 

XVI :    Mar..     87 

PRUGER.   RAOUL 

Reducing     Mechanical     Difficulties    with 

Motot^Driven    Applications 

XVIII:     Sept..  408 

RAMEY.  B.  B. 

Interchangeability    of    S  q  u  i  r  r  e  1-Cage 

Rotors  XVI:    Nov..  481 

RANDALL.  K.  C. 

Heavy  Alternating-Current  Conductors.... 

XVI :    Aug..  343 

Current  Limiting  Reactors  Commonly 
Protect    Both    Service   and    Equipment 

XVII :    June.  248 

RANSOM.   ALLEN  E. 

Electric  Dredging  on  the  Yukon 

XVI:     Mar..     86 

REACE.  WM.  T. 

Improved  Industrial  Lighting 

XVI :    May.  197 

Merchandising    Electrical    Appliances 

XVH:    May.  229 

READ.  E.  K. 

The  Control  Room  Circuit  Breaker 
Equipment  of  the  U.   S.   S.  Tennessee 

XVIII :    June,  258 

REDDIE,  W.  W. 

Arc  Welding  Equipment  in  the  FoundiT 

XVIII:    Mar.,     96 

Westinghouse  Technical  Night  School 

XVIII :    Apr..  1.50 

REED,  E.  G. 

The  Essentials  of  Transformer  Practice. 

XVIII — Phase  Transformation  

XVI:    Jan.,     31 

XIX — Operating  Conditions 

XVI :    Feb..     66 

XX — Three-Phase    to    Two-Phase    Trans- 
formation    with     Single-Phase    Trans- 
formers  Scott   Connected. .. .XVI :   Mar.,     96 
XXI— Voltage       Transformations       with 

Autotransformers   XVI:    Apr..  145 

XXn — Phase  Transformation  with  Auto- 
transformers    XVI:    May.  216 

XXIII— Parallel  Operation  ...XVI :  June.  267 

XXrV— Polarity   XVI:   July.  301 

XXV — Voltage  Transformers   

- XVIII:    July.  323 

Steel   Clad  Distribution   Transformers 

XVII:    May.  213 

REID.  HARRY 

Dealing  with  the  Public  and  Employees 
(E)    XVIII:   Oct..  442 


RIKER.  CHAS.  R. 

Insulator  Characteristics  (E)..XVI:  Jan..       7 

The  Journal— A  Text  Book   (E) 

XVI :    Mar..     83 

Three-Phase  to  Two-Phase  Transforma- 
tion  (E)  XVI:  Mar..     83 

European   Switchboard   Practice    (E) 

XVI :   June.  234 

Graphical  Solutions   (E) XVII:   Mar..     83 

Small  Turbine  Development   (E) 

- XVII :   Apr..  127 

Appliance  Outlets    (E) XVII:  July.  277 

The  Trail  of  the  Pioneer   (E) 

XVII:   July.  277 

Modern  Testing  Equipment    (E) 

XVII :    Aug..  319 

Electric  Power  for  Refrigeration   (E) 

XVII :    Nov..  501 

Abnormal   Motor  Voltages    (E) 

- XVII:    Dec.  539 

Question   Box  Service   (E).. XVIII:   Aug..  335 
RODMAN.  C.  J. 

A  New  Form  of  Standard  Cell 

XVIII:    Feb..     65 

ROOT.  F.  S. 

The  Central  Station  and  the  Textile  Mill 

XVIII:   Nov..  487 

ROUX.  GEORGE  P. 

Load   Dispatching   System   of   the   Phila- 
delphia Electric   Company.. XVI :    Nov..  470 
RUGG,  W.  S. 

The  Stability  of  the  Electric  Street  Rail- 
way Industry   (E)  XVI:  Oct..  406 

Specifications     of     a     Successful     Street 

Railway    XVll:    Octo..   430 

Radio— Its  Relation  to  the  Electrical  In- 
dustry   (E)    _ XVIII:    Apr..   109 

The    Battleship   is   a   Fighting  Ship    (E) 

XVIII:    June.  2S8 

RILEY.  L.  G. 

Enlarging  the  Field  for  Remote  Control 

XVII:    Feb..     39 

Methods  of  Protecting  Electrical  Equip- 
ments    XVII:    Oct..  453 

RYDER.  H.  M. 

The  Relations  Between  Gases  and  Steel. 

XVII :    Apr..  161 

The  Dry   Cell   Radio  Vacuum  Tube 

XVIII :  Dec.  536 

RY LANDER.  J.  L. 

Insulation  for  Steel  Mill  Motors 

XVIII :    Sept..  405 

Commutator  Insulation   Failures 

XVIII:    Dec.  654 

ST.  JOHN.  H.  M. 

Electric  Brass  Melting— Its  Progress  and 

Present  Importance XVI:   Sept.,  373 

SAMPSON.  E.  R. 

Transformers  for  Synchronous  Convert- 
ers    XVIII:    Nov..  518 

SCHAAKE.   W. 

3000  Volt  Current  Collectors  for  the  Chi- 
cago. Milwaukee  &  St.  Paul  Locomo- 
tives   XVII:   July.  278 

SCHEIN.  ALEXANDER  E. 

The  Gyroscopic  Stabilizer  on  the 

donia"  XVIII : 

SCHENCK.  S.  B. 

Multiple-Unit  Train  Operation 

XVII :  Oct..  457 

SCHIEBER.  A.  L. 

The  Development  of  Our  Water  Powers 

(E)    _.. XVIII:   Dec,  523 

SCHLUEDERBERG,   C.   G. 
Developing      Our      Electrochemical      Re- 
sources   (E)    XVI:  Jan..       3 

SCHOENFELD.  O.  C. 

The  Design  of  Induction  Motors  for  Tex- 
tile  Service   XVIII:   Nov..  494 

SCHOEPFLIN.  H.  V. 

Lubrication   of  Steam   Turbine   Bearings 

XVII :    Mar..     90 

SCHUCHARDT.   R.  F. 

The  Significance  and  the  Opportunities 
of   the   Central   Station   Industry    (E)  . 

XVI :    May,  166 

SCOTT,  CHAS.  F. 

The     Development     of     the     Two-Phase. 

Three-Phase    Transformation 

-..- XVI:    Jan..     28 

Finding  the  Size  of  Wire   (E) 

XVI :    July.  276 

Charles  Wood  Johnson — An  Apprecia- 
tion     XVII:   June.  234 

SCOTT.  GUY  F. 

The   Liquid  Slip   Regulator.. XVIII :  Jan..     37 
SCOTT.  WIRT  S. 

Industrial   Electric  Heating 

XVI :    May.  188 

SEARS.  E. 

Snow  Fighting  Methods  on  the  Electri- 
fied Section  of  the  Chicago,  Milwaukee 

&   St.  Paul  Railroad XVIII:  Jan.,     39 

SELS.  H.  K. 

Transmission      Line     Circuit     Constants 

and   Resonance   XVIII:   July,  306 

Transmission    Line    and    Transformers.... 

XVIII :    Aug.,   356 

Power-Factor  Correction   in  Steel  Mills.. 

XVIII :    Sept.,  419 

Circle  Diagrams  for  Transmission  Sys- 
tems    XVIII:    Dec,  530 


'*Lyn- 
Aug.. 


SHAND.  E.  B. 

A     Vector     Diagram     for     Salient-Pole 

Alternators  - XVIII:  Feb.. 

Principles  and  Characteristics  of  Syn- 
chronous Motors  XVIII:  Mar.. 

Starting  Characteristics  of   Synchronous 

Motors  XVIII:  July. 

SHEPARD.  F.  H. 

Expansion     of     Railroad     Electrification 

(E) XVI:  Jan.. 

Chicago.  Milwaukee  £  St.  Paul  Electri- 
fication   (B)   XVII:  Jan., 

SHONTS.  THEODORE  P. 

Utility    Credit    and    General    Prosperity 

(E)    XVI:  Oct.. 

SHRADER.  J.  E. 

Conduction   in   Liquid   Dielectrics 

-..- XVI:   Aug.. 

Vacuum  and  Heat  Treatment  of  Insulat- 
ing Materials  _ XVII:   Apr.. 

SIMONS.  DONALD  M. 

Allowable  Working  Stresses  in  High- 
Voltage  Electric  Cables XVII:  July.  : 

SKINNER.  C.  E. 

Post-War  Engineering  Problems   (E) 

XVI :    Jan., 

The  Story  of  the  Insulations. 

....- XVII:    Apr..  : 

International    Standardization    (E) 

XVII:  July,  i 

SKINNER.  M.  E. 

Three-Phase   Current    Limiting   Reactors 

XVIII:    Jan.. 

The  70.800  Kv-a  Transformer  Bank  of 
the  Colfax   Generating   Station   of   the 

Duquesne   Light   Co XVIII:   May.  : 

SLEPIAN.  J. 

The  Flow  of  Power  in  Electrical  Ma- 
chines     _ XVI:    July.  ! 

Why  High   Frequency  for  Radiation  7 

XVIII:    Apr..  1 

SMITH.  B.  H. 

The  Power  Indicating  and  Limiting  Aiv 
paratus  for  the  Chicago.  Milwaukee  & 

St.  Paul  Railroad XVIII:  Feb., 

SMITH,  FRANK  W. 

The  Manufacturer  and  the  N.  E.  L.   A. 

(E)    -....- XVIII:   May.  ] 

SMITH.  GERALD  F. 

Main  Driving  Motors  for  the  Chicago. 
Milwaukee  &  St.  Paul  Passenger  Loco- 
motives  XVII:    July.  : 

SMITH.  HAROLD  W. 

Interconnection    of   Power   Systems 

- XVII:    Nov..  I 

Electrical  Transmission  vs.  Coal  Trans- 
portation     XVIII:    Sept..  ' 

SMITH.  HARRY  S. 
The  Induction-Type  Frequency  Changer,. 

XVII:    Aug.,  ; 

SMITH,  JOHN  H. 

Condensing   Equipment   and  Oil    Cooling 

System  for  the  U.   S.  S.  Tennessee 

— XVIII:    June,  ! 

SMITH,  W.  NELSON 

Reminiscences  of  the  Erie  Electrification 

at  Rochester  XVIH :  Jan.. 

SNIFFIN.  E.  H. 

What  the   Utilities  Have  Gained    (E) 

XVI :    Jan.. 

Power  House  Economics   (E) 

XVI:    May.  : 

The  Engineer  and  the  Community 

XVI :  June.  ! 

The  Water  Power  Bill   (E) 

XVII:    Aug..  ; 

A  Perspective  View   (E) XVIH:  Jan.. 

Now  for  the  N.  E.  L.  A.  Convention  (E) 

XVIII:  May,  1 

SOUTHGATE.  H.  M. 

Electric  Drive  and  the  U.  S.  S.  Ten- 
nessee    - XVIII:    June.  ', 

SPERRY.  E.  A. 

The  Gyro  Stabilizer  for  Ships    (E) 

XVIII:    Aug.. 

SPOONER.   THOS. 

Adjustable    Laboratory   Rheostats 

XVIII :     Feb.. 

A  New  Form  of  Standard  Cell _. 

XVIII :  Feb.. 

Methods  of   Magnetic  Testing 

XVIII:  July.  316:  Aug..  351;  Dec.  i 

STAEGE.   STEPHEN  A. 

Automatic    Speed    Control    for   Sectional 

Paper  Machine  Drive XVIII:  Mar.. 

STAIR.  J.    L. 

Lighting  without  Hanging  Ceiling  Fix- 
tures— A  Tendency  in  Modern  Light- 
ing Methods  XVI:  May. 

STEPHENS.  H.  D. 

Use  of  Mica  Insulation  for  Alternating- 
Current  Generators  XVI:  Mar.. 

What  Are  Safe  Operating  Tempera- 
tures  for  Mica  Insulation  ? 

XVI:    Apr.. 

STIEFEL.  J.   B. 

Winding   Railway   Motor   Armatures 

XVII :     Oct.. 

STILLWELL.  LEWIS   BUCKLEY 

Calvert     Townley.     President     American 

Institute  of   Electrical   Engineers 

XVI :    July. 


THE  ELECTRIC  JOURNAL 


STINEMETZ,  W.  E. 

The  Function  of  Regeneration   (E) 

XVII:    Feb.,     39 

3T0FFEL,  T.  H. 

Freight  Service  on  Electric  Railways 

XVIII :    Oct.,  474 

STOLLER.  H.  M. 
Development     of     Airplane     Radio-Tele- 
phone Set  XVI:   May,  211 

STOLTZ,  G.  E. 

Electrically-Driven    Plate    Mills 

XVI :     Feb.,     69 

The  Electric  Motor  in  the  Steel  Mill   (E) 

XVII:     Sept.,  360 

Dependable  Driving  Equipment    (E) 

_ JCVIII :    Sept.,  384 

STONE,  E.  C. 

The    Function    of    the    Load    Dispatcher 

(E)    XVI:    Nov.,  469 

The     Transmission     Ring     of     the     Du- 

quesne  Light  Company XVIII:  May,  211 

STORER,  N.  W. 

The  Graduated  Fare  System    (E) 

- XVI :     Oct.,  417 

The  New  Passenger  Locomotives  for  the 
Chicago,  Milwaukee  &  St.  Paul  Rail- 
road   _ XVII:  Mar.,     84 

STORRS,  LUCIUS  S. 

Public  Understanding,  Consideration  and 
Appreciation  Necessary  for  a  Solu- 
tion of  the  Electric  Railway   Problem 

(E)   XVI:    Oct.,  408 

STOTZ,  J.  K. 

Effect  of  Short-Time  Overloads  on  Rail- 
way  Motor  Armatures XVII:   Oct.,  473 

Some  Mechanical  Causes  of  Flashing  on 

Railway  Motors  XVIII:  Oct..  481 

STRAIT,  JOHN  M. 
The  Automatic  Electric  Bake  Oven. 

„ XVIII:     July.  296 

SYKES,  WILFRED 

Electrical  Propulsion  for  Battleships  (E) 

XVIII :    June,  237 

TAYLOR,  T.  S. 

The  Thermal   Conductivity  of  Insulating 

and  Other  Materials XVI:  Dec.  626 

TERRY,  CHAS.  A. 

A  Tribute  to  Albert  Schmid 

XVII :    Feb.,     40 

TERVEN,  L.  A. 

Typical    Relay    Connections 

XVIII:  Jan.,  29;  Feb.,  61;  Mar.,    99 

THAU,  W.  E. 

General  Arrangement  of  Propelling  Ma- 
chinery of  the  U.  S.  S.  Tennessee 

XVIII :    June,  245 

THOMAS,   P. 

The  Comparison  of  Small  Capacities  by 

a  Beat  Note  Method XVIII:  Aug..  349 

THOMPSON,   A.   W. 

City   Traction    Problems    (E) 

XVI :     Oct..  409 

The  Relation  of  the  Electric  Railway  to 
the  Community   (E)   XVIII:  Oct..  443 


THOMPSON,  R.  G. 
Dynamotors    and    Wind-Driven    Genera- 
tors   XVI:  May,  20B 

TILTON,  BENJAMIN  E. 
Mutuality  of  Interests  in  Practice  (E).... 

XVI :     Oct.,  418 

TOWNLEY,  CALVERT 

The  New  South  Philadelphia  Works   (E) 

XVI:    Apr..  Ill 

The  Edison  Medal  (E) 

XVI:   June.  233 

Service  at  Cost    (E) XVI:   Oct..  416 

Increased  Railroad  Rates  as  an  Accel- 
erator of  Electrification   (E) 

XVII:  Oct.,  488 

Futures   (E)   - XVIII:   Oct..  438 

TRIPP.  GUY  E. 

A  Central  Station  Opportunity  (E) 

XVI :     Feb..     45 

Effect  of  Electrical  Removal  of  Limita- 
tions   (E)    XVII:   May.  174 

Public  Utility  Economics   (E) 

_ XVIII :   Jan..       1 

The  Necessity  for  Publicity  in  Business 

(E)    XVIII:   Oct..  428 

TEITLE,  J.  S. 

Co-Operation  Between  Operators,  Car 
Builders  and  Equipment  Manufactur- 
ers (E)  XVI:  Oct.,  421 

TURNER.  H.  M. 

Education  of  Radio  Engineers  at  Yale... 

_ XVIII:    Apr.,  149 

WAGNER.  GEO.  E. 

Three-Phase   Four-Wire  Distribution 

XVI :    Mar.,     99 

WALES.  S.  S. 
The   Power   System   of   the   U.    S.    Steel 

Corporation  in  Pittsburgh 

XVIII:     May,  222 

WEBER.  C.  A.  M. 
The   Electrically    Operated   Gyratory 

Riddle  XVI:    June  263 

WEBSTER,  A.  D. 

Automatic  HL  Control  for  Boston  Sur- 
face  Cars  XVI:   Oct.,  469 

WELLS,  W.  F. 
The  National  Electric  Light  Association 

for  1919   (E)  XVI:  May,  163 

WELSH.  J.  W. 

Service  versus  Fares   (E) XVII:  Oct..  436 

WENSLEY.  R.  J. 

Standard  Automatic  Substation  Equip- 
ment  XVI:     May.  218 

The  Electrostatic  Glow  Meter „ 

XVI:    May,  228 

WEST,  D.  C. 

The  New  Liquid  Rheostats  for  the  Nor- 
folk &  Western  Railway.. ..XVII:  Oct.,  483 
WHEELWRIGHT,  THOS.  S. 

Public    Utilities— A   Diagnosis   (E) 

XVI :     Oct.,  414 

The  Trackless  Trolley  or  Trolley  Bus  (E) 
_ XVIII:     Oct.,  439 


WHITCOMB,  ARTHUR  J. 

The     Application     of    Adjustable     Speed 

Main  Drives  in  the  Steel  Mill 

XVII :     Sept.,  367 

WHITE.  J.  A. 

Portable  Electrical  Equipment  for  Mo- 
tion   Picture   Photography 

XVIII :  Feb.,     71 

WHITTAKER,  C.  C. 

Layout  of  Apparatus  in  the  Cab  of  the 
Chicago,  Milwaukee  &  St.  Paul  Loco- 
motives   XVII:  June,  249 

A     Slip     Arrester     for     Heavy     Electric 

Locomotives   XVII:    Oct.,  446 

WILEY,   BRENT 

Post  War   Steel  Conditions    (E) 

XVI :    Jan.,       6 

Motor-Driven  Steel  Mills  (E) 

XVI :     Sept.,  357 

Electric  Drives  for  Steel  Mills   lE) 

XVII :     Sept.,  361 

The   Use    of    Central    Station    Power   by 

Industrial    Plants    (E) XVIII:    May,  164 

WILSON,  A.  L. 

Remote  Control  by  Radio....XVIII :  Apr.,  146 
WILSON,   G.  P. 

Oil    Current    Breaker    Arrangement    and 

Switching  Schemes  for  Steel  Mills 

XVH:      Sept.,  402 

Substations  for  Reversing  Mill  Motors.... 

_ XVIII :    Sept.,  389 

WIMMER.  E.  P. 

Phase  Transformation  with  Autotrans- 
formers — Three-Phase     to     Two-Phase 

Three-Wire  XVIII:  Jan.,     15 

WINSHIP,   L.  C. 

Renewal  of  the  Catenary  Construction  in 

the  Hoosac  Tunnel XVIII:   Mar.,     84 

WOOD.  L.  A.   S. 

Ornamental  Street  LightinB..XVII :  May,  195 
WOODSON,  J.  C. 

The   Automatic   Electric   Bake   Oven 

- XVIII:    July,  296 

WOODWARD,  W.  R. 
Testing  for  Short-Circuit  Currents  with 

Miniature  Networks  XVI:  Aug..  344 

WORKER.  JOSEPH  G. 
F\iel     Burning     Equipment    of    Modern 

Power  Stations  XVI:  Feb.,     65 

WORTMAN.  O. 

Electrification    of   the   Central    Limones, 

Cuba  XVII:  Oct.,  477 

WRIGLEY,  GEORGE 
Individual     Motor    Drive    for    Spinning 

and  Twister  Frames 

_ XVni:    Nov.,  501 

WYNNE,  F.  E. 

Selection  of  Motors  for  Service  Condi- 
tions   (E)    XVII:   Oct.,  434 

YENSEN.  T.  D. 

The  Development  of  Magnetic  Materials 

XVIII:    Mp.r.,     93 

YOUNG,  H.  W. 

Farm  Line  Business  at  a  Profit  to  the 
Central    SUtion   XVII:    Feb.,     79 


The  Electric  Journal 


VOL.  XVIII 


January,  1921 


No.  1 


The  street  railway  and  electric  light 
Public  Utility  and  power  industries  are  beginning  a 
Economics  "ew  and  distinct  economic  era.  They 
have  passed  through  perhaps  as  many 
different  economic  phases  as  there  have  been  different 
scientific,  mechanical  and  engineering  periods  in  the  in- 
dustry. We  can,  however,  secure  an  interesting  view- 
point of  the  present  development  of  what  may  be  called 
the  public  economics  of  public  utilities  without  referring 
to  any  more  remote  period  of  time  than  the  few  years 
just  before  the  world  war.  At  that  time  regulation  of 
public  utilities,  on  the  sole  theorj'  of  restraining  or  curb- 
ing private  enterprise,  had  reached  its  full  development 
and  it  had  carried  with  it  some  results  which  contained 
both  good  and  bad  elements,  although  the  final  outcome 
was  bad,  as  was  inevitable. 

One  of  the  good  aspects  was  that,  by  reason  of  the 
public  belief  in  the  "naturally"  huge  profits  of  the  in- 
dustry and  in  the  necessity  for  a  check  upon  them  by 
the  means  of  repressive  regulation,  there  was  created  an 
atmosphere  of  financial  security  and  opportunity  which 
was  attractive  to  investors,  and  which  made  possible  the 
development  of  these  properties  fast  enough  to  keep 
pace  with  the  needs  of  the  people. 

It  is  true  that  during  the  latter  part  of  this  repres- 
sive period  the  managers  and  operators  of  public  utili- 
ties, and  particularly  street  railways,  saw  danger  ahead 
and  loudly  called  for  a  new  dispensation.  They  de- 
manded, in  effect,  a  removal  of  their  case  from  the 
criminal  court  to  a  court  of  equity. 

The  apparent  result  of  these  protests  was  nothing. 
Even  the  growing  number  of  receiverships  of  street 
railway  companies  had  very  little  effect  upon  the  public 
mind  because  they  were  told  by  advocates  of  one  kind 
and  another  that  each  individual  case  stood  by  itself 
and  was  the  result  of  high  finance  or  bad  management, 
or  something  else  peculiar  to  the  individual  company  it- 
self. That  there  was  anything  fundamentally  wrong 
with  repressive  regulation  was  vigorously  denied. 

Then  came  the  war  and  it  was  evident  that  all 
enterprises  which  were  under  governmental  regulation 
stood  on  the  verge  of  bankruptcy.  It  was  a  nation- 
wide condition  of  all  regulated  public  utilities  and  at  a 
time  when  unregulated  business  was  enjoying  high 
prosperity. 

Perhaps  this  situation,  standing  alone,  would  not 
have  moved  a  reform,  but  the  additional  fact  that  the 
Nation  had  to  finance  a  great  war  and  that  it  would 
have  been  impossible  to  do  so,  in  the  face  of  a  national 


bankruptcy  of  railroads  and  other  public  utilities,  led  to 
the  inauguration  of  the  present  era.  It  is  an  accepted 
theory  now  that  one  of  the  duties  of  regulatory  bodies 
(and  in  some  cases  it  is  made  mandatory  by  law)  is  to 
consider  the  financial  needs  of  public  utility  companies 
in  a  positive  manner  as  distinguished  from  the  former 
negative  system. 

There  has  arisen  under  this  new  dispensation  (and 
quite  naturally)  a  method  of  measuring  the  compensa- 
tion to  the  private  capital  and  enterprise  engaged  in  the 
industries,  called  the  cost  of  service  system,  which  how- 
ever comprises  many  different  plans. 

The  idea  of  Cost  of  Service  is  not  an  entirely  new 
one,  but  its  general  acceptance  gives  it  a  new  position  of 
importance;  it  has  almost  reached  the  point  of  becom- 
ing the  slogan  for  the  settlement  of  all  public  utility 
questions.  Like  most  condensed  expressions,  "Cost  of 
Service"  may  mean  many  things  to  many  people;  and, 
unless  it  can  be  defined  so  thoroughly  and  widely  that 
the  public  will  understand  what  it  must  mean  if  it  is  to 
be  successfully  applied  to  private  ownership  and  opera- 
tion of  public  utilities,  there  is  danger  in  it. 

The  public  ought  to  realize  that  private  enterprise 
will  not  be  attracted  to  any  private  industry  in  which 
the  door  is  closed  to  all  reward  beyond  the  mere  interest 
on  the  money  invested,  and  that  a  successful  "Cost  of 
Service"  plan  must  include  some  probability  of  profit 
over  and  above  mere  interest. 

There  is  little  doubt  that  the  public  generally  does 
not  so  understand  "Cost  of  Service"  at  the  present  time, 
and  it  will  be  well  to  be  sure  that  the  minds  of  the 
parties  in  interest,  viz.  the  public  and  owners  and  opera- 
tors of  utilities,  have  met  before  encouraging  the 
further  use  of  the  expression  as  a  slogan. 

Profit  may  be  provided  for  in  a  variety  of  ways,  but 
permitting  the  possibility  of  its  attainment  is  the  only 
way  to  secure  the  energy  and  economy  of  private 
ownership  and  operation,  and  I  suppose  the  new  school 
of  regulation  is  designed  to  secure  and  encourage  that 
very  thing,  for  I  believe  the  public  has  endorsed  private 
ownership  and  operation. 

In  order  that  present  day  regulatory  methods  may 
be  successful,  it  will  also  be  necessary  that  the  public 
utilities  co-operate  with  the  regulatory  authorities  in 
every  proper  way,  because  no  one  can  predict  just  what 
the  public  reaction  will  be,  as  the  working  out  of  the 
future  public  utility  problems  proceeds,  and  as  the  com- 
missioners exercise  their  power  and  duty  to  raise  rates 
as  well  as  to  reduce  them.     It  has  been  ven,'  reassuring 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


so  far,  and  the  public  has  accepted  the  decisions  of  their 
commissioners  with  a  readiness  which  shows  a  complete 
confidence  in  them ;  and,  speaking  generally,  there  is  no 
indication  of  any  incipient  dissatisfaction. 

However,  that  is  no  reason  for  a  relaxation  of  the 
efforts  of  public  utilities  to  co-operate  in  all  possible 
ways,  and  there  is  one  policy  which  will  be  helpful  in 
the  situation ;  one,  fortunately,  that  will  also  be  of  direct 
benefit  to  the  utilities  themselves.  I  refer  to  the  suc- 
cessful efforts  which  are  now  being  made  in  several  sec- 
tions of  the  country  to  sell  the  common  stock  of  utili- 
ties to  local  investors  in  small  blocks.  This  plan  is  al- 
most ideal.  In  the  first  place,  it  tends  to  that  healthy 
condition  where  the  local  people  own  the  equity  in  their 
own  utility.  They  have  an  investment  in  a  property 
which  they  see  and  use  every  day.  It  is  almost  an  ideal 
investment  because  the  people  themselves  by  their  own 
actions  assist  in  insuring  the  stability  of  their  own  in- 
vestment, and  they  need  never  sustain  losses  except  by 
their  own  action  or  by  that  of  their  own  representatives 
in  public  office. 

The  "foreign"  security  owner  tends  to  become 
simply  a  lender  of  money,  having  an  investment  secured 
by  mortgage,  and  he  will  be  content  with  a  lower  rate  of 
return  because  a  substantial  local  ownership  of  stock  is 
an  insurance  of  safety  to  the  investor  in  bonds  and  that 
fact  must  improve  the  credit  of  a  utility. 

The  widespread  local  ownership  of  common  stock 
of  a  public  utility  ought  also  to  be  the  strongest  pillar 
of  support  to  regulatory  bodies  in  their  new  role,  which 
i."^  bound  to  be  a  more  difficult  part  to  play  than  their 
old  one.  Therefore,  I  regard  the  vigorous  extension  of 
the  policy  of  local  sale  of  common  stock  of  public  utili- 
ties to  be  an  indispensable  adjunct  to  the  present  system 
of  public  regulation  in  that  it  will  tend  to  protect  it 
against  a  possible  reaction  of  the  public  mind.  I  regard 
this  new  era  as  a  great  step  in  advance  of  anything  that 
has  heretofore  existed  in  the  field  of  public  regulation 
of  public  utilities,  and  what  I  have  said  is  meant  only 
to  suggest  a  point  of  danger  which  we  should  have  in 
mind. 

As  previously  stated,  I  believe  private  ownership 
and  operation  have  been  endorsed  by  the  people  and 
future  administration  of  utilities  will  be  based  upon  that 
policy  unless  for  one  reason  or  another  regulation  falls 
into  such  an  impasse  with  natui"al  business  or  economic 
laws,  that  government  ownership  will  be  the  only  solu- 
tion. There  is,  however,  less  likelihood  of  such  an  out- 
come now  than  ever  before  in  the  history  of  public  utili- 
ties, at  least  since  they  have  become  a  vital  factor  in  the 
daily  life  of  the  people. 

Sound  economics  have  not  been  preached  for  years 
without  effect.  The  outlook  is  an  encouraging  one  and 
I  look  for  the  early  restoration  of  the  credit  of  public 
utilities  under  a  method  of  regulation  which  will  in  time 
place  their  securities  next  to  government  obligations. 

G.  E.  Tripp 


A 

Perspective 
View 


About  sixty  million  of  our  population 
live  under  electric  wires.  Of  this 
great  number  of  people,  every  man, 
woman  and  child  requires  something 
over  one  kilowatt-hour  per  day  to  take  care  of  his  or 
her  needs  and  comforts.  From  the  time  we  rise  in  the 
morning  until  we  retire  at  night  we  use  electric  current. 
We  light  with  it,  we  heat  with  it,  we  are  transported 
by  it  and  we  operate  our  factories  with  it.  In  a  myriad 
of  ways  it  ministers  to  our  necessary  uses.  It  is  one  of 
the  principal  elements  of  our  present  civilization.  Ob- 
vious as  this  may  be,  it  is  a  good  way  to  start  thinking 
about  the  electrical  business,  particularly  in  relation  to 
its  future  prospects.  The  electrical  industry  embraces 
the  manufacture  and  use  of  machinery,  apparatus,  de- 
vices and  materials  for  the  generation,  transmission  and 
absorption  of  electrical  energy-.  A  large  number  of 
plants  are  engaged  in  these  manufactures.  Many  thou- 
sand of  central  stations  generate  and  distribute  the 
power  to  large  communities.  Isolated  plants  exist  in 
great  number  in  factories,  in  office  buildings,  in  hotels 
and  the  like,  although  the  drift  of  power  supply  is  in- 
evitably of  economic  necessity  toward  the  central  sta- 
tion. 

Viewing  the  electrical  business  in  its  numerous  as- 
pects it  would  be  hard  to  find  any  other  industry  which 
is  more  sound.  It  is  sound  from  the  investors  stand- 
point because  it  is  based  on  a  public  need  growing  all 
the  time,  and  it  is  generally  well  financed.  It  is  sound 
from  a  public  standpoint,  as  it  gives  more  for  the  money 
than  anything  else  which  is  manufactured  and  sold.  It 
furthermore  is  not  a  profiteering  business.  In  all  its 
branches  the  profits  are  very  moderate.  It  is  sound 
from  a  national  standpoint  because  it  offers  the  great- 
est possible  means  of  conserving  our  national  resources, 
building  up  new  communities  and  making  new  enter- 
prises possible.  It  possesses  the  economic  advantage  of 
a  steady  growth  which  can  be  fairly  predicted,  permit- 
ting of  a  reasonable  parity  of  facilities  and  demand. 
Finally,  it  is  a  business  of  great  moral  soundness,  where 
the  work  is  constructive,  the  results  genuine  in  public 
benefit,  where  good  hearts  cheerfully  give  the  best  they 
have.  Its  men  are  high  grade  and  so  are  its  methods. 
For  the  past  fifteen  or  twenty  years  the  consump- 
tion of  electrical  energy  per  capita  has  doubled  about 
ever>'  five  years.  This  rapid  growth  has  necessitated 
much  new  financing,  requiring  for  the  utility  companies 
somewhere  between  fifty  and  one  hundred  dollars  of 
new  capital  for  each  person  that  is  added  to  their  popu- 
lation served.  With  high  rates  for  new  money,  with 
operating  and  construction  costs  mounting  skyward, 
and  with  very  little  increase  in  their  service  rates,  their 
burden  has  been  very  heavy.  But  their  condition  is  im- 
proving. Rate  increases,  though  small,  have  brought 
relief.  Operating  costs  show  a  lowering  tendency,  and 
the  utilitv  securities  are  gaining  in  favor.  The  great 
thing  about  the  electrical  industi-j  is  the  continual  im- 
provements in  the  art  which  have  made  the  cost  of  elec- 


January,   1921 


THE   ELECTRIC  JOURNAL 


trie  power  lower  and  lower,  while  most  other  necessi- 
ties have  become  dearer.  The  inventor,  the  engineer, 
the  mechanician,  the  scientist  have  all  been  able  to  frus- 
trate the  economic  laws  which  in  most  commodities 
have  robbed  the  dollar  of  its  vitality.  Today  a  pound 
of  coal  burned  at  the  central  station  will  deliver  to  your 
house  something  like  425  candle-power  hours.  Twenty 
years  ago  it  was  about  85.  Each  unit  of  apparatus  in 
the  long  train  of  transformations  between  that  pound  of 
coal  and  vour  electric  light  has  experienced  tremendous 
improy  c:.ient,  and  so  have  the  methods  of  their  use. 

if  Jonathan  Swift's  Brobdingnagian  was  right, 
that  a  man  who  grew  two  blades  of  grass  where  one  had 
grown  before  deserved  more  of  mankind  than  the  whole 
race  of  politicians  put  together,  what  would  he  say  of 
our  engineering  brethren  who  have  multiplied  so  many 
times  the  service  to  our  communities  of  the  energy  in 
our  coal  and  in  our  rivers  and  streams.  And  the  beauty 
of  it  all  is,  they  put  no  plumes  or  flags  upon  their 
triumphs.  Neither  pausing  nor  gloating,  they  push  on 
to  new  experiments,  new  realms  of  adventure,  to  dream 
and  to  do,  giving  to  the  world  their  harvest,  these  "fire- 
hearts  who  sow  our  furrows".  It  means  a  good  deal, 
no  doubt,  that  the  electrical  industry  in  all  its  branches 
employs  something  like  one  and  one-half  million 
workers,  and  some  eighteen  to  twenty  billion  dollars  of 
capital,  and  that  three  or  four  percent  of  our  population 
live  directly  from  its  revenues.  But  more  important 
still  is  the  intimate,  permeating  relation  of  electrical 
energy  to  every  other  industry  and  every  individual 
throughout  the  civilized  globe.  You  can't  get  away 
from  it  unless  you  go  into  the  wilds,  catch  your  own 
food  and  make  your  own  clothes  and  your  own  shelter, 
with  tools  fashioned  by  your  own  hands.  And  the 
chances  are  it  would  reach  you  there.  So  it  is  bound 
to  be  a  great  business,  worthy  of  any  man's  ambition  if 
he  has  the  genius  of  a  worker  and  the  spirit  of  a  pro- 
ducer.. Big  things  have  been  done,  but  there  are  bigger 
to  do.  Let  new  discoveries  come  when  they  will.  We 
cannot  hurry  them  nor  predict  what  they  hold  for  us 
or  for  posterity.  There  is  plenty  to  do  that  we  know 
about.  The  industry  has  grown  so  rapidly,  the  art  has 
improved  so  frequently  under  the  stimulus  of  demand 
that  the  new  standards  of  one  year  were  superseded  the 
next.  Apparatus  and  methods  become  antiquated  long 
before  the  amortizing  capital  can  be  found.  As  a  con- 
sequence there  are  tremendous  wastes  going  on  which 
must  sooner  or  later  be  stopped.  The  engineer  points 
the  way.  The  economist  and  the  financier  must  give 
their  aid.  Above  all  things  the  public  itself  which  is  so 
reliably  and  so  cheaply  served  by  the  utility  companies, 
which  indeed  owns  the  utility  companies,  must  see  to  it 
that  these  companies,  under  the  proper  regulation  which 
they  welcome,  are  permitted  by  adequate  rates  and  by 
proper  legislation  to  maintain  their  properties  at  high 
efficiency  and  with  a  fair  rate  of  return.  The  public 
service  company  is  a  public  benefit.  You  can't  figure 
it  any  other  way.     That  being  so,  it  is  to  the  interest  of 


every  community  and  to  the  national  interest  of  the 
country  that  it  have  the  most  intelligent  public  co-opera- 
tion and  support.  E.  H.  Sniffin 


The 

Problem 

of  the 

Electric 

Railways 


"Things  have  changed  somewhat  in 
their  time",  and  so  has  the  electric 
railway  industry.  In  fact,  things  in 
this  industry  have  developed  a 
marked  change  for  the  better.  The 
men  in  charge  of  electric  railway 
properties  today,  by  and  large,  are  men  of  vision. 
There  is  hardly  one  who  does  not  thoroughly  grasp  the 
problems  confronting  them. 

It  is,  however,  one  thing  to  understand  a  problem 
and  know  what  the  solution  is,  but  quite  another  to  find 
ways  and  means  to  achieve  the  desired  results.  This 
latter  is  really  the  biggest  task  confronting  electric 
railway  executives.  The  one  big  obstacle  standing  in 
the  way  in  most  instances,  is  the  public  itself — meaning 
by  this,  all  that  public  opinion  and  public  good  will  em- 
brace because,  after  all,  this  includes  such  things  as 
credit,  patronage,  taxes,  operating  expenses,  restric- 
tions, etc. 

Specifically,  the  great  majority  of  electric  railways 
need  increased  revenue  in  order  to  operate  existing 
facilities  satisfactorily.  The  public,  on  the  other 
hand,  need  and  should  have  more  and  better  service. 
Our  transportation  facilities  have  not  kept  pace  with 
the  growth  of  communities  and,  as  previously  men- 
tioned, the  people  themselves  stand  in  the  way,  but  the 
people  generally  do  not  know  this,  and  hence  cannot  be 
expected  to  take  steps  to  correct  it.  Great  strides  have 
been  made  during  the  past  few  years  by  progressive 
electric  railway  executives  in  making  the  public  ac- 
quainted with  facts  regarding  the  difficulties  en- 
countered in  providing  adequate  transportation  facili- 
ties, but  complete  mastery  of  this  modem  art  will  take 
considerable  time.  Marked  instances  of  its  mushroom 
growth  and  achievements  are  quite  apparent.  Among 
these  are  the  "Illinois  Committee  on  Public  Informa- 
tion", and  similar  organizations  in  other  states ;  the  con- 
structive work  and  publicity  of  the  American  Electric 
Railwav  Association  Reconstruction  Committee  and  the 
Committee  of  One  Hundred  in  connection  with  the 
]'"ederal  Electric  Railway  Commission;  the  Committee 
on  Merchandising  Transportation,  Electric  Railway 
Freight  Haulage,  and  numerous  other  invaluable  ac- 
complishments of  the  American  Electric  Railway 
Association,  the  Central  Electric  Railway  Association 
and  other  state  associations.  Complete  mastery  of  the 
;n-t  of  publicity  will  not  be  eflfected  and  the  full  mea- 
sure of  its  force  will  not  be  secured  until  national  and 
state-wide  activity  is  backed  up  and  fully  supported  by 
local  publicity  work  and  performance. 

The  electric  railways  need  credit.  It  is  quite  im- 
possible to  get  it  with  an  inadequate  income.  It  is 
almost  impossible  to  get  an   adequate   income  without 


THE   ELECTRIC  JOURNAL 


\'o\.  XVIII,  No.  I 


the  good  will  of  the  public ;  hence,  the  necessity  of  cul- 
tivating and  establishing  the  good  will  of  each  local 
community. 

Practically  all  railway  executives  are  alive  to  the 
potent  force  of  this  abstract  thing  which  we  call 
"publicity".  In  the  past  many  thought  it  consisted  very 
largely  in  having  one  man  write  copy  for  use  in  the 
papers  or  in  pamphlets.  But  they  know  now  that  it  is 
a  very  much  bigger  thing — a  sort  of  phantom  giant 
force  that  is  susceptible  of  direction  and  guidance  and, 
when  properly  guided,  it  is  capable  of  producing  re- 
markable results.  Il  becomes  really  active  only  when 
every  executive  and  subordinate  officer  is  thoroughly 
imbued  with  the  spirit  of  the  game,  and  then  only  when 
it  is  the  job  of  some  strong  staff  officer  or  headed  up  by 
a  manager  of  public  relations,  with  a  staff  of  copy 
writers. 

Recently  a  university  professor  presented  an  out- 
line of  a  four-year  university  course  planned  as  a  spe- 
cial administrative  or  executive  training  course.  The 
four  years  were  divided  up  into  groups  of  studies  in 
the  various  branches  of  electric  railway  operation  run- 
ning for  three  or  four  months  each.  Thus  there  was 
civil  engineering  to  cover  track  and  bridges;  a  few 
months  in  electric  engineering,  power  plants,  cars  and 
locomotives ;  some  more  on  transmission  lines ;  and 
other  periods  on  accounting,  banking,  passenger  and 
freight  traffic,  etc.  I  told  him  he  had  left  out  the  most 
important  study  of  all,  and  that  was  a  fundamental 
grasp  of  how  to  deal  with  people — both  employes  and 
the  public.  And  herein  lies  the  former  missing  link  in 
the  public  utility  game.  Most  of  us  were  trained  on 
the  engineering  and  physical  side  of  the  industry,  and 
few  gave  much  thought  to  the  very  important  thing  we 
now  call  "publicity"  for  want  of  a  better  or  more  de- 
scriptive term. 

Therefore,  as  stated  at  the  outset,  things  have 
changed  somewhat;  the  smoke  screen  has  been  cleared 
away.  It  is  now  generally  accepted  that  the  one  biggest 
nut  to  Crack  is  that  of  securing  the  good  will  of  the 
people  we  serve  and  their  representatives.  It  is  regret- 
able  that,  when  the  industry  as  a  whole  had  made  such 
a  good  running  start  in  this  game,  a  business  depression 
should  set  in;  on  the  other  hand,  it  may  all  be  for  the 
best.  It  will  likely  prove  to  be  of  great  value  in  re- 
lieving the  tension  and  thus  permit  more  deliberate 
thought  and  action  during  the  few  months  of  business 
let-up.  It  should  not,  however,  be  an  excuse  for 
"marking  time"  but  rather  a  time  for  thorough  organi- 
zation and  preparation.  The  people  generally  will  have 
relaxed  and  will  be  more  inclined  to  stop,  look  and 
listen  to  advice  and  mformation.  Without  doubt,  busi- 
ness will  come  back  in  a  few  months.  It  always  has 
come  back  and  the  general  needs  of  the  country  are 
such  that  actual  requirements  now  existing  will  tend  to 
restore  business  as  soon  as  the  people  feel  that  prices 
have  reached  a  new  normal  level,  and  a  few  months 


will,  we  believe,  establish  this.  One  sure  way  to  help 
this  is  to  get  the  public  to  favor  public  utility  demands 
for  increased  revenue  and  then  tell  them  about  the  new 
cars  and  other  equipment  that  have  been  purchased  to 
provide  better  service.  Myles  B.  Lambert 


Present 

Trend  of 

Electrical 

Development 


The  present  trend  of  electrical  de- 
velopment, as  it  has  been  for  several 
years,  is  toward  an  ever  widening  use 
of  electricity  in  every  sphere  of  " 
hvmian  activity.  This  movement  has 
been  so  rapid,  and  its  results  so  con- 
spicuous, as  to  awaken  the  industry 
to  a  realization  that  its  proportions  have  changed.  For 
many  years  the  products  of  the  industry  which  pre- 
dominated were  those  used  in  power  houses  and  on 
street  cars.  Then  the  motor  had  its  day  in  the  manu- 
facturing field.  And  now  the  home  and  the  farm  are 
turning  out  to  be  the  biggest  market  of  all.  Today  for 
every  dollar  spent  for  electrical  apparatus  for  the  pur- 
pose of  generating  electrical  current,  three  dollars  are 
spent  to  transmit  and  distribute  it  to  users,  and  eight 
dollars  are  spent  for  apparatus  and  supplies  to  utilize  it. 
The  ratio  of  consumption  to  generation  is  now  eight  to 
one,  while  not  so  long  ago  it  was  only  three  to  one. 

Until  about  fifteen  years  ago,  the  electrical  railway 
was  the  thing  but  since  then,  due  to  causes  with  which 
we  are  all  familiar,  that  branch  of  the  industry  has 
come  upon  evil  days,  and  committees  of  one  hundred, 
with  a  sublime  and  touching  faith,  make  solemn  and 
obsequious  declaration  of  its  wrongs. 

In  the  meantime,  the  central  station  people,  as  we 
call  them  in  the  vernacular  of  our  industry,  have  come 
to  the  front.  They  had  a  hard  time  in  the  early  days 
when  they  had  only  light  to  sell.  They  wisely  took  on 
power  and  that  helped  a  lot.  They  kept  on  plugging  and 
digging  and  finally  they  struck  a  reservoir  greater  than 
any  they  had  previously  tapped.  It  turned  out  to  be  a 
"gusher"  for  they  had  finally  reached  the  great  Ameri- 
can public  in  a  new  way,  with  comfort-giving  and  bur- 
den-lightening electrical  service ;  and  the  use  of  elec- 
tricity now  goes  beyond  the  bounds  of  industry  and 
reaches  the  place  of  business  and  the  home.  It  has  at 
last  become  the  universal  servant  of  mankind. 

The  principal  result  of  this  change,  which  was  not 
abrupt  but  gradual,  was  to  make  electrical  apparatus 
known  to  the  public,  to  rob  it  of  its  mystery  and  to  have 
it  accepted  as  merchandise,  similar  to  other  goods  pur- 
chased over  the  counter.  Out  of  the  eight  dollars 
spent  for  apparatus  to  consume  and  utilize  current  one- 
half,  at  least,  is  spent  by  the  general  public,  and  out  of 
the  three  dollars  spent  for  transmitting  current  (which 
includes  the  wiring  of  buildings)  almost  two  dollars  is 
also  ultimately  spent  by  the  public.  Therefore,  out  of 
every  twelve  dollars  spent  six  dollars  are  spent  by  the 
public.  Half,  at  least,  of  the  electrical  market  is  now 
removed  from  the  field  of  technical  negotiation  and  is 
conducted  on   mercantile   lines.      The   public   can   be 


January,  1921 


THE  ELECTRIC  JOURNAL 


reached  only  by  merchandising  methods.  These  in- 
volve problems  of  quantity  manufacture,  warehousing, 
distribution  through  middlemen  and  other  problems  of 
a  commercial  nature  which  have  been  met  and  solved 
by  merchants  down  the  ages,  but  which  are  new  to  us. 
While  they  differ  from  the  highly  technical  ones  in- 
volved in  the  design  and  production  of  electrical  ap- 
paratus, they  are,  nevertheless,  keenly  interesting,  and 
the  electrical  industry  is  endeavoring  to  meet  them  with 
an  open  mind,  free  from  the  retarding  influences  of  in- 
herited bad  business  practices,  and  upon  a  high  plane  of 
business  ethics.  The  engineering  mind  should,  after 
proper  experience,  be  able  to  contribute  something  to 
the  methods  of  commerce,  and  the  electrical  industry 
now  has  a  special  opportunity  in  that  particular. 

The  most  remarkable  features  of  this  extraordi- 
nary development  have  been  the  "electrification"  of  the. 
household  and  of  the  farm.  Electrical  devices  have 
lightened  the  burdens  of  the  housewife  and  have  helped 
the  farmer  to  increase  production. 

While  the  commercial  or  merchandising  develop- 
ment stands  out  most  prominently  in  the  present  situa- 
tion, there  are  other  tendencies  which  should  be  noted. 
One  phase  of  the  widening  use  of  electricity  has  been 
particularly  noticeable  in  the  field  of  manufacturing. 
Not  only  has  motor  drive  been  wonderfully  extended, 
but  the  use  of  electricity  otherwise  in  manufacturing 
processes,  particularly  in  the  form  of  heat  producing 
devices,  has  been  notable,  and  has  been  developed  to 
a  point  where  wonderful  possibilities  are  in  sight.  It  is 
held  by  some  engineers  that  the  consumption  of  elec- 
trical current  in  heat  for  industrial  applications  will  in 
time  exceed  the  consumption  of  current  for  motor 
power  drive. 

Electricity  now  has  a  recognized,  acknowledged 
position.  It  is  estimated  that  this  country  now  needs 
at  least  a  million  homes,  fifty  thousand  factory  and  rail- 
road buildings  and  twenty  thousand  public  buildings. 
Is  it  conceivable  that  any  one  of  them  will  not  be  wired? 
The  architect  would  as  soon  think  of  leaving  off  the 
roof. 

There  has  been  a  tendency  in  the  electrical  indus- 
try towards  co-operative  effort  which  has  been  remark- 
able. It  is  doubtful  whether  anything  of  the  kind  has 
ever  occurred  in  any  other  industry,  and  it  is  fitting  that 
this  comparatively  new,  young,  vigorous  industry 
should  set  an  example  for  all  others.  And  it  is  well 
that  this  spirit  has  inspired  the  industry,  for  the 
enormous  and  rapid  development  has  brought  into  ex- 
istence a  large  number  of  individual  units  in  each 
branch  of  the  industry.  There  are  several  hundred 
manufacturers  of  electrical  apparatus,  several  thousand 
distributors  of  all  kinds  and  several  thousand  public 
utilities.  It  is  something  to  be  proud  of  when  we  think 
that  the  progress  so  far  made  has  been  based  on  the 
intrinsic  merit  of  the  products  of  the  industry  and  de- 
veloped under  methods  of  clean  competition. 

John  J.  Gibson 


The  industries  of  this  countrj'  have 
The  l^cen    large    purchasers    of    electrical 

Electrification  niachinery.  durjug.  the  past  six  years. 
of  This  buying  has  been  continuous  and 

Industry  in  great  volume,  except  for  a  short 

period  of  uncertainty  following  the 
signing  of  the  Armistice.  During  the  war  period  the 
industrial  and  mining  companies  were  first  called  upon 
to  purchase  machinery  for  manufacturing  war  ma- 
terials in  great  quantities  and  supplying  the  require- 
ments of  a  hastily  mobilized  army.  Somewhat  later, 
additional  machinery  was  required  to  supply  the 
enormous  demands  of  the  people  for  all  classes  of  mer- 
chandise, both  necessities  and  luxuries. 

As  is  well  known,  the  products  of  the  first  phase 
of  this  period,  from  an  economic  point  of  view,  have 
been  dissipated.  However,  the  money  placed  in  circu- 
lation started  an  era  of  prosperity  in  all  lines  of  manu- 
facture which  was  accentuated  to  some  extent  by  the 
mental  reaction  of  the  people  from  the  thrift  practiced 
during  the  war,  by  the  greater  private  incomes  and  by 
the  restrictions  imposed  upon  manufacturers  of  non- 
essentials during  war  conditions. 

The  purchases  of  machinery  by  industrial  organi- 
zations have  been  largely  for  plant  expansion  to  obtain 
increased  output.  The  dominating  fact  of  interest  to 
all  branches  of  the  electrical  industry  is  that  in  this  ex- 
pansion practically  all  industrial  organizations  planned, 
IS  a  matter  of  course,  to  use  electrical  machinery  for 
their  power  requirements  and  furthermore,  that  such 
electric  power  was  purchased  from  central  power  sta- 
tions wherever  possible,  in  preference  to  making  the 
investment  for  a  private  source  of  supply. 

While  these  factors  have  caused  a  severe  strain 
upon  the  facilities  of  all  branches  of  the  electrical  in- 
dustry .^manufacturer,  distributor  and  central  station, 
yet  the  recognition  of  the  advantages  of  electric  power 
by  all  industrial  organizations  is  a  source  of  great  sat- 
isfaction and  hope  for  the  future  of  the  electrical  busi- 
ness. 

The  coming  year  will  undoubtedly  see  the  purchase 
of  improved  modern  machinery  for  rehabilitation  pur- 
poses, looking  towards  more  economical  production  to 
meet  competitive  conditions.  It  is  confidently  felt, 
however,  that  electrical  apparatus  and  machinery  will 
play  just  as  important  a  part  in  this  phase  of  the 
general  business  situation  as  it  has  in  supplying  the 
power  foi  plant  extensions. 

The  large  field  for  the  application  of  electrical  ma- 
chinery and  apparatus  to  all  industries,  the  develop- 
ment of  new  and  improved  apparatus  by  the  engineers 
and  the  increasing  popularity  of  electrical  devices 
among  all  classes  of  people  gives  encouragement  for  the 
future  to  all  branches  of  this  great  industry. 

J.    M.   CURTIN 


iljklit^xr 


M.  R.  ARMSTRONG 

Industrial  Heating  Section, 
W  estinghouse  Electric  &  Mfg.  Company 

\i  umiii  ,ii:  .,■,.^,lin^^  liavc  becH  made  during  the  hst  decade  in  the  manner  of  applying  paint  and  enamel 
to  automobiles.  The  original  method  was  to  app!y  air-drying  paint  or  enamel  by  hand  with  a  brush.  The 
next  step  was  dipping  the  various  small  metal  parts  in  a  baking  enamel  and  then  baking  them  in  gas-fired 
ovens.  The  hand  painting  of  large  parts,  such  as  chassis  and  body  has  been  replaced  by  the  use  of  an  air 
spray,  using  a  baking  enamel.  The  gas  oven,  on  account  of  its  many  disadvantages,  is  being  supplanted  by 
electricallj-heated  ovens.  These  modern  method^  arc  well  exemplified  in  the  automobile  plants  of  the 
Jordan  Motor  Car  Company  and  the  Cleveland  Automobile  Company  in  Cleveland,  Ohio.  The  methods 
used  in  these  plants  and  the  results  of  tests  made  on  their  electrically-heated  ovens  are  discussed  in  this 
article. 


THE  ENAMEL  for  many  of  the  small  parts  at 
the  plant  of  the  Jordan  Motor  Car  Company  is 
baked  in  an  electricallj'-heated  oven  of  the  semi- 
continuous  conveyer  type.  This  oven,  Fig.  i,  is  20  ft. 
long,  9.5  ft.  wide,  and  7.75  feet  high  inside  measure- 
ment. It  is  thermally  insulated  with  four  inches  of 
non-pareil  brick  and  is  encased  with  sheet  iron  linings. 
The  conveyer  extends  through  the  oven  and  for 
about  30  feet  outside  of  the  oven  at  each  end,  returning 
over  the  top    as  shown  in  Figs.  1  and  2.     It    i'^  moinr 


thermostat.  At  present  both  sections  are  being  con- 
trolled by  the  thermostat.  Doors  at  each  end  are 
equipped  with  switches  which  cut  oft  the  power  to  the 
heaters  when  either  door  is  opened.  This  eliminates 
any  danger  from  live  connections,  and  also  the  possi- 
bility of  wasting  heat  by  having  the  heaters  turned  on 
while  the  doors  are  open. 

At  each  end  of  the  conveyor  is  a  dip  tank,  one  of 
which  contains  the  first  coat  enamel,  and  the  other  ihat 
for  the  second  and  third  coats.  These  dip  tanks  are 
filled  from  an  elevated  storage  tank,  which  is  supplied 
by  motor-driven  pumps  taking  the  enamel  from  the  drip 


FIG.    I — SEMICONTINUOUS    C0N\tV0R   TYPE   OVEN    FOR    B.\KIXC 
EN.\MEL   ON   AUTOMOBILE   PARTS 

driven  and  can  be  operated  in  either  direction.  The 
ventilating  inlet  air  ducts  are  located  in  the  floor  along 
the  sides  of  the  oven,  and  have  a  series  of  holes  over 
their  entire  length,  so  that  the  incoming  air  is  evenly 
distributed  along  the  sides  directly  underneath  the 
heaters  which  are  mounted  on  the  side  walls.  The  ex- 
haust ducts  take  the  air  from  near  the  floor  at  the  four 
comers  of  the  oven  and  deliver  it  to  the  outside  of  the 
building.  The  air  is  handled  by  a  inotor  driven  ex- 
haust fan. 

The  electrical  heating  equipment  consists  of  64 
oven  heaters  having  a  total  capacity  of  173  kw.  The 
heaters  are  controlled  by  a  three-phase,  double  section 
control  panel.  This  panel  is  so  arranged  that  one  or 
both  groups  of  the  heaters  can  be  operated  by  the  oven 


Kl>_,.    2 — 0V1..\    A.N'l.    l>iill'   TAXK 

The  fenders  on  the  conveyor  are  ready  to  be  run  into  the  oven. 
Innks  which  are  located  underneath  the  conveyor  at 
both  ends  of  the  oven. 

The  parts  as  received  from  the  shrp  are  offcn 
rusty  and  greasy,  and  must  be  cleaned  thoroughly  he- 
fore  they  can  be  enameled,  as  the  durability  and  finish 
of  the  enamel  depeiids  upon  the  smoothness  and  clean- 
ness of  the  parts.  To  remove  the  rust,  they  are  dipped 
in  a  muriatic  acid  bath.  Fig.  3,  and  then  rinsed  thor- 
oughly with  water.  They  are  next  dipped  in  a  caustic 
soda  bath,  Fig.  4  to  remove  the  grease.  After  the  parts 
have  been  thoroughly  rinsed  again  and  dried,  they  are 
rubbed  with  fine  sand  paper  to  remove  all  roughness. 

From  the  cleaning  room  the  parts  are  taken  to  the 
first  coat  dipping  tank,  where  the>  are  dipped  and  hung 
on  the  conveyor  to  drip.  After  dripping  a  sufficient 
length  of  time,  they  are  run  into  the  oven  and  another 
load  is  dipped  and  hung  on  the  conveyor  to  drip.     The 


January,  1921 


THE   ELECTRIC  JOURNAL 


average  baking  period  is  about  50  minutes.  This 
allows  about  15  minutes  for  dipping  the  next  load,  and 
35  minutes  for  it  to  drip  before  the  first  load  is  removed 
from  the  oven.  When  the  first  baking  has  cooled  suffi- 
ciently, it  is  taken  from  the  conveyor  into  the  rubbing 
room  Fig.  5,  where  it  again  receives  a  thorough  rub- 
bing. 

The  heat  control  of  the  oven  is  entirelj-  automatic 
and  no  labor  is  required  for  its  operation  other  than 
dipping  the  parts  and  hanging  them  on  the  conveyor. 

TABLE  I— OPERATING  CHARACTERISTICS  OF 
ELECTRIC  OVEN 


and  the  length  of  time  that  the  power  was  of?,  between 
the  bakes,  was  considerably  above  the  average.  As  d 
result  the  efficiency  was  very  low.  The  third  bake  had 
rather  a  heavy  load  and  the  time  interval  between  this 
and  the  previous  bake  was  about  normal,  as  a  result  the 
efficiency  was  high.  A  comparison  of  bakes  No.  4  and 
No.  6  shows  that  while  the  load  of  No.  6  was  less,  the 
efficiency  was  higher.  This  can  be  accounted  for  by 
the  fact  that  the  time  the  power  was  oiT  preceding  the 


Bake 

I 

2 

3 

4 

5 

6 

Avg. 

Pounds    Baked    ...... 

Minutes  for  Dipping. . 
Minutes  for  Dripping 

Minutes   Baking   

Kw-hr 

Lbs.  Baked  per  Kw-hr. 
Min.   Current   was   on 

555 
21 
37 
72 
65.6 
9.8 
22 

293 

12 

53 
60 
67.2 
44 
22 

1043 
22 
57 
60 

78.4 
13-3 

28 

683 
23 
36 
60 

57.6 
1 1.8 
21 

381 
14 
44 
65 
544 
7.0 
20 

638 
16 
41 
45 
52.8 
12.1 
19 

597 
18 
41 
63 
67.; 
9.0 
22 

Tests  were  made  recently  to  determine  the  operat- 
ing characteristics  and  the  cost  of  operating  the  electric 
ovens.  The  results  obtained  for  the  different  bakes  are 
shown  in  Table  I  and  the  temperature  curves  in  Figs. 
6  and  7.     All  the  tests  were  on  the  last  or  finish  coat. 

Although  the  average  number  of  pounds  baked  per 
kilowatt-hour  is  somewhat  lower  than  is  common  in 
ovens  of  this  type,  some  of  the  bakes,  taken  under 
favorable  conditions,  show  a  very  good  efficiency.  It 
seems  that  the  two  factors  which  affect  the  efficiency 
most  are  the  number  of  pounds  put  into  the  oven  per 


FIG.  4— C.\USTIC  SOn.\  DATII   .\ND  CLE.^NING  TAllLES 

Grease  and  dirt  are  removed  in  the  caustic  soda  bath.  The 
roughness  is  removed  by  rubbing  the  parts  with  fine  sand  paper. 

bake  was  27  minutes  against  35  for  No.  4.  No.  5  bake 
had  both  a  light  load  and  a  52  minutes  time  inter\al 
with  power  off  before  the  bake  was  started. 

On  the  basis  of  nine  bakes  per  day  as  shown  on  the 
temperature  chart.  Fig.  7,  using  the  average  energy 
consumption  of  68  kw-hr.  per  bake  and  the  number  of 
cars  per  day  as  22,  the  kw-hr.  consumption  per  car 
would  be  27.6.  At  a  power  rate  of  1.63  cents  per  kw- 
hr.  this  \vould  amount  to  45  cents  per  cnr. 


FIG.   3— REMOVINi;   RUST  BY  DIPPING   PARTS   IN    A    MURIATIC 
ACID   BATH 

bake  and  the  length  of  time  that  the  power  is  cut  ofif 
between  the  bakes. 

Taking  up  the  bakes  in  their  order,  No.  i  is  about 
the  average  in  weight,  and  the  length  of  time  elapsed, 
between  cutting  off  the  power  from  the  proceeding  bake 
and  the  start  of  this  bake  was  slightly  below  the  aver- 
age. The  efficiency  was  what  could  be  expected  from  an 
oven  of  this  type.   In  No.  2  bake,  (he  load  was  very  light 


5       KLUBI.NG    KOO-M 

After  the  first  baking  bas  cooled  all  the  fenders  receive  a 
thorough  rubbing. 

The  uniform  temperature  line  on  the  temperature 
chart.  Fig.  6,  from  7  P.  M.  to- 10  P.  M.  shows  the  tem- 
perature held  during  a  test  to  determine  the  radiation 
of  this  oven  with  the  doors  and  all  .the  vents  closed. 
This  test  shows  a  power  loss  of  56  kw-hr.  due  to  radia- 
tion or  an  average  loss  of  56.6  watts  per  sq.  ft.  at  a 
temperature  of  400  degrees  F.  The  results  obtained  in 
the  radiation  test  are  not  the  true  losses  of  the  oven 
under  operating  conditions.  The  temperature  charts 
also  show  that  the  oven  is  up  to  the  maximum  tempera- 
ture of  400  degrees  for  only  a  small  percentage  of  the 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


time  so  that  the  average  temjierature  of  the  oven  for 
normal  operation  is  much  lower  than  the  temperature 
applied  during  the  radiation  test.  Temperature  meas- 
urements, taken  during  the  radiation  test,  show  that  for 
an  average  oven  temperature  of  400  degrees  F.,  a  tem- 
perature of  130  degrees  F.  was  maintained  on  the  out- 
side walls,  with  a  room  temperature  of  67  degrees  F. 

CLEVELAND  AUTOMOBILE   COMPANY 

The  oven  used  by  the  Cleveland  Automobile  Com- 
pany for  baking  the  enamel  on  their  chassis  is  120  ft. 
long,  100  inches  high  and  62.5  inches  wide,  outside  di- 
mensions. The  entrance  end  is  entirely  open,  the  exit 
end  has  a  flap  covering  the  opening  about  one  third  the 
way  down.  The  walls  of  the  oven  are  constructed  of 
two  inch  non-pareil  brick  encased  between  sheet  iron 
linings.  The  work  is  carried  on  a  conveyor  through  the 
oven  at  the  rate  of  2.5  ft.  per  min.     This  conveyor  ex- 


FIG.   6 — TEMPERATURE  TEST  CHART 

Showing  operating  characteristics  of  the  electric  oven. 

tends  about  75  ft.  at  both  ends  of  the  oven.  The  oven 
is  ventilated  by  a  fan,  which  is  driven  by  a  1.5  hp  motor 
at  450  r.p.m.  The  size  and  the  location  of  the  intake 
and  exhaust  vents  are  shown  in  Fig.  8. 

The  electrical  heating  equipment  consists  of  112 
oven  heaters,  arranged  along  the  sides  of  the  oven  and 
distributed  to  give  a  carefully  graduated  temperature 
throughout  the  oven.  These  heaters  are  connected  in 
three  circuits,  two  control  and  one  constant  heat  circuit. 
Each  circuit  is  controlled  by  a  contactor  panel,  with  a 
snap  switch  to  control  all  three  panels.  The  entrance 
and  exit  circuits  are  under  thermostatic  control.  The 
electric  heaters  in  the  center  are  on  the  constant  heat 
circuit.  The  entrance  control  circuit  is  on  all  the  time 
while  the  exist  circuit  operates  over  a  cycle  of  about 
13.5  min.  on  and  46.2  min.  off. 

As  the  chassis  is  assembled,  it  is  gradually  worked 
toward  the  starting  end  of  the  oven  conveyor.  The 
completely  assembled  chassis  is  placed  on  the  conveyor 


which  carries  it  to  the  enamel  spraying  machines  ar- 
ranged so  that  the  operators  are  on  opposite  sides  of 
the  chassis.  These  spray  stations  are  provided  with 
hoods    equipped    with    motor-driven    exhaust    fans    to 


/ 

tCV  12*- 20'  \ 

'             lordan  Molnr  Cn 

WiO\ 


/  / 


•♦** 


FIG.    7— TEMPERATURE  CHART  OF   AN   AVERAGE  DAYS   RUN 

carry  off  the  fumes.  The  enamel  used  is  especially 
made  for  use  in  spray  machines.  About  12  gallons  of 
enamel  are  used  on  a  daily  output  of  55  chassis  or  0.2 
gallon  per  chassis.  Before  entering  the  oven,  the 
chassis  are  carefully  inspected  to  see  that  no  spot  has 
been  missed  and  that  the  coat  is  uniform.  The  trip 
through  the  oven  requires  about  50  minutes.     As  soon 


FIG.   8— LONCITUniNAL   ELEVATION'   OF   CHASSIS   OVEN 

Position  of  intake  vents  and  dampers,   a— wall   side  part 
open  and  b — room  side  part  open. 

as  they  emerge  from  the  oven,  grease  is  placed  in  the 
transmission  and  housing,  and  most  of  the  assembling  is 
completed  before  the  chassis  leaves  the  conveyor. 


January,  1921 


THE  ELECTRIC  JOURNAL 


Records  of  the  temperature,  throughout  the  oven, 
were  made  with  a  recording  thermometer  having  the 
recording  mechanism  enclosed  in  a  wooden  box.  The 
thermometer  bulb  was  exposed  to  the  heat  and  located 
in  the  center  of  the  path  of  the  work.  The  box  was 
set  on  the  conveyor  and  sent  twice  through  the  oven. 
"Hie  temperatures  from  the  resulting  chart  were  taken 
for  points  of  time  corresponding  to  ten  feet  of  travel 
and  plotted  on  the  longitudinal  elevation  sketch  of  the 
oven,  Fig.  8.     The  temperatures  at  each  of  the  exhaust 


vents  were  taken  by  placing  a  thermocouple  in  the  pipe 
about  six  inches  above  the  oven  top.  These  tempera- 
tures are  plotted  on  the  same  sketch  at  points  directly 
underneath  the  points  at  which  they  are  taken. 

At  the  time  this  data  was  obtained,  the  average 
hourly  consumption  was  213  kw-hr.  and  the  number  of 
chassis  treated  was  six  per  hour.  Each  chassis 
weighed  750  pounds  making  a  total  weight  of  4500 
pounds  per  hour.  This  gives  a  production  of  21.  i 
pounds  per  kw-hr. 


CojidMctor^  wM\  Stool  c^oio-s 

H.  B.  DWIGHT 

STEEL  CORES  are  frequently  used  in  transmission  line  conductors,  especially  where  the  conductor 
material  is  aluminum,  in  order  to  increase  the  strength  to  a  desirable  amount.  The  steel  core  has  a  distinct 
effect  on  the  electrical  characteristics  of  the  cable,  and  the  amount  of  this  effect  may  be  estimated  in  the 
manner  described  in  the  following  article. 


THE  effect  of  the- addition  of  a  steel  core  to  a 
transmission  line  cable  is,  first,  to  decrease  the 
resistance  by  an  amount  which  may  be  two  per- 
cent, more  or  less,  and  second,  to  decrease  the  react- 
ance, usually  by  a  smaller  percentage.  It  will  be 
shown  later  that  a  useful  approximate  rule  for  trans- 
mission calculations  is  to  take  the  conductivity  of  the 
steel  cored  cable  as  being  equal  to  the  sum  of  the  con- 
ductivities of  the  core  (for  alternating  current)  and  the 
copper  or  aluminum,  and  to  take  the  reactance  of  the 
complete  cable  .is  if  the  core  were  made  of  non-mag- 
netic material,  the  same  as  the  rest  of  the  cable. 


FIG.    I — SECTION  OF  CABLE  AND  CORE 

Ordinarily  the  reactance  of  a  transmission  line  is 
due  chiefly  to  the  magnetic  flux  in  the  air  surrounding 
the  conductors.  The  magnetic  flux  in  the  air  is  not  of 
interest  in  the  present  problem  however,  for  it  cuts  both 
the  core  and  the  outer  wires  of  the  cable  equally.  The 
effect  of  the  flux  inside  the  cable  should  be  calculated, 
since  it  alters  the  distribution  of  current  between  the 
core  and  the  remainder  of  the  cable. 

The  non-magnetic  wires  of  a  cored  cable  form  a 
tube  of  outer  radius  r  and  inner  radius  g,  Fig.  i.  Neg- 
lecting the  current  in  the  core,  which  is  small,  the  total 
current  inside  the  circle  of  radius  x  is, — 

'i  =  If  i  (x"  —  g")  abamperes (/) 

Where  i  is  is  the  current  density  in  abamperes  per 
square  centimeter,  and  where  the  dimensions  are  in  cen- 


timeters.    The  flux  density  at  radius  x  is, — 

~. — =  2  Tt  i  yx  —  -~  j lines  per  sq.  cm (/) 

The  total  flux  in  the  ring  outside  the  circle  of 
radius  x  is  obtained  by  integrating  from  x  to  r  and  is 
equal  to, — 

0.  =  TT  1    \^^  _  ^  _  ^g,  i^gi^  —  j  lines  per  cm (3) 

The  reactive  drop  at  rau.us  x  due  to  the  above  flux 
is, — 

f  01  cpx  ^  }'  ic  TT  i  (r'  —  x'  ■ — 2g'  logh    -—jabvolts  per  cm.. .   (4) 

Where  w  =  2  tt  f  and  where  /  is  the  frequency  in 
cycles  per  second. 

To  find  the  average  reactive  drop  due  to  the  above 
flux  multiply  the  element  of  area,  2  v  x  dx,  by  the  drop 
in  that  element,  given  by  (4),  integrate  over  the  sec- 
tion of  the  tube  and  divide  by  the  area  of  section  of  the 
tube.     This  gives, — 

(49*  ''  \ 

r  —  39' •\-  r'  —  g-    '''^''   c  j  "^^""-f  Z'^'' "»•    (5)* 

Assume  that  the  diameter  of  the  core  is  1/3  that 
of  the  complete  cable,  which  is  usually  very  nearly  the 
case,  then  g  =^1/3  r,  and  the  average  reactive  drop  in 
the  tube  is, — 


I  J.  10 
i  y  w  T  i  r°  X  — To — abvolts  per  cm. 


(6) 


Let    the    total     current    in    the    tube,    equal    to 

IT  i  (r^  —  (7^),  be  represented  by  (o  -f-  ;  6)  amperes. 

Then  the  reactive  drop  in  the  tube  is, — 

,    .  13.10        9   /a  +  jb  \      ,     , 

a  ;  w  X—jg —  X  -g-  \^^ )    abvolts  per  cm (7) 

This  is  equivalent  at  60  cycles  to, — 

0.0248  i  (a  +  J  b)  volts  per  mile (8) 

Let  R  be  the  resistance  of  the  tube  in  ohms  per 


♦"The    Inductance    of    Tubular    Conductors,"    by    H.    R 
Dwight,  The  Electrical  Review,  Feb.  9,  1918,  p.  224. 


THE   ELECTRIC  JOURNAL 


\'ol.  XVIII,  No.  I 


mile.     Then  the  impedance  drop,   taking  into  account 
only  the  flux  considered  above,  is, — 

(o  +  /  b)   {R  +  j  0.0248)  volts  per  mile  (?) 

Now  the  alternating  magnetic  flux  considered 
above  cuts  the  core  as  well  as  the  tube  The  total  flux 
is  given  by  (3),  putting  x  =  q,  and  is, — 

TT  i  r"  (/— —  X  /./o )    lines  per  cm (/o) 

The  reactive  drop  in  the  core  due  to  this  flux  is, — • 

5.80 
}  u  ^  i  r  y.   abvolts  per  cm (//) 

Which  is  equivalent  to,— 

;'  (a  +  j  b)  0.0440  ohms  per  mile  ( t?) 

Let  the  current  in  the  steel  core  be  c  +  ;  d  am- 
peres. The  impedance  of  the  core  due  to  its  effective 
resistance  and  the  flux  inside  the  steel,  may  be  taken 
with  reasonable  accuracy  from  the  curves  published  in 
the  Journal  for  January  1919.**  Let  the  impedance 
given  by  the  curves  be  i?i  +  /  X^  for  a  certain  assumed 
current  in  the  core.  Then  the  drop  in  the  steel  core 
is, — 

(c  +  i  d)   (Ri  +  j  X,)  +  /  (a  +  /  b)  0.0440  volts 

per  mile  ( -f j) 


The  current  in  the  complete  cable 
r=-  £  (^totat  admittance) 


=  H^ 


R,  +  /  X, ) 


;  0.0192 

In  this  way  the  effective  resistance  R'  and  react- 
ance X'  of  the  complete  cable  may  be  calculated,  since- 

the  total  admittance  found  above  is  equal  to^r — ^  .  „, 
It  is  found  that  the  current  in  the  core  is  usually  so- 
small  that  its  effect  in  producing  magnetic  flux  in  the 
cuter  part  of  the  cable  may  be  neglected,  as  was  done  in 
the  above  calculation.  The  current  in  the  outer  part  of 
the  cable  is  to  the  current  in  the  core  in  the  ratio  of 
their  admittances,  and  that  is  very  closely  in  the  inverse 
ratio  of  their  resistances. 

A  few  examples  are  shown  in  Table  I.  The  re- 
sistances and  reactances  are  in  ohms  per  mile.  The 
line  reactances  are  based  on  spacings  which  would  be 
usual  for  transmission  line  work.  It  may  be  observed 
from  the  table  that  a  683  000  circ.  mil  cable  composed 
of  600000  circ.  mils  of  aluminum  and  a  steel  core,  has 
a  larger  diameter  and  therefore  nearly  one  percent  less- 
reactance  than  a  600000  circ.  mil  cable  without  a  core. 


TABLE    1- 

—EXAMPLES 

OF   TRANSMISSION   CABLES   WITH 

STEEL 

CORES 

^St 

s'sl  >. 

■-   3 

■      Outer  VVii 
of  Cable 

•" 

r,„-c 

Current 

.■\ssuined  for 

Core 

Ri 

R 

K' 

3^? 
a  - 

X, 

X 

X' 

It- 

600  000  Giro. 

Mil 

5/16"   Cable,   Or- 

30 Amperes 

7.6 

0.153 

0.150 

1.8 

2.0 

2.0 

0.760 

0.754 

0.8 

dinary  Steel. 

60  Cycles 

600  000  Circ. 

Mil 

5/16"  Cable,  Or- 

lo Amperes 

6.4 

0.153 

0.149 

2.2 

2.3 

1.3 

0.760 

0.754 

0.8 

Aluminum 

dinary  Steel. 

60  Cycles 

600  000  Circ. 

Mil 

5/16"  Cable.  Or- 

30 Amperes 

6.5 

0.152 

0.148 

2.2 

2.3 

1.1 

0.317 

0.31S 

dinary  Steel. 

25  Cycles 

1.3 

400  000  Circ. 

Mil 

9/32"  Cable,   Or- 

20 Amperes 

8.6 

0.228 

0.223 

2.3 

2.5 

2.0 

dinary  Steel. 

60   Cycles 

0.8 

250  000  Circ. 

Mil 

No.  6  B.  W.  G.  Wire 

12.5  Amperes 

20.8 

0.364 

0.359 

1.3 

1.8 

9.8 

0.767 

Aluminum 

Ordinary  Steel. 

60  Cycles 

o.e 

150  000  Circ 

Mil 

No.  8  B.  W.  G.  Wire 

7.5  Amperes 

23.3 

0.605 

0.592 

2.1 

2.5 

9.0 

0.777 

Aluminum 

Ordinary  Steel. 

60  Cycles 

!  and  Reactance  are  in  Ohms  per  Mile.     X  is  the  Reactance  of  a  600000  ( 


num  cable  having  i 


This  may  be  equated  to  (9)  since  the  core  and  the  tube 
are  in  electrical  contact  and  take  up  a  distribution  of 
current  such  as  to  give  the  same  voltage  drop  in  each. 
Therefore, 
Therefore, 

(c  +  j  d)  (R,  +  j  A\)  =  (o  +  /  b)  (R  +  j  0.0248  —  y  0.0440) 
:=:  (a  -\-  j  b)   (R  —  /  0.0192)  volts  per 

mile  at  60  cycles  (14) 

The  term  0.0192  becomes  0.0080  at  25  cycles.  This 
is  the  same  as  the  usual  equation  for  two  impedances  in 
parallel:  Thus,  let  each  side  of  equation  (14)  be  equal 
to  E 

Then,  o  +  ;'  fc  =: 


and,  c  -^  j  d  = 


R  —  /  0.0192 

E 
/?,  +  j  X. 


♦♦"Resistance   and    Reactance   of   Commercial    Steel    Con- 
ductors," by  H.  B.  Dwight,  the  Journal  for  Jan.  1919,  p.  25. 


A  683  000  circ.  mil  cable  with  an  83  000  circ.  mil  core 
has  0.2  percent  more  reactance  than  a  683  000  circ.  mil 
all  aluminum  cable.  Although  the  core  offers  a  mag- 
netic path  to  the  flux  of  self-inductance,  the  amount  of 
effective  flux  in  the  core  is  small,  since  a  steel  core  of 
one-third  the  diameter  of  the  cable  carries  only  about 
one-fiftieth  of  the  total  current. 

In  conclusion,  a  close  approximation  to  the  elec- 
trical characteristics  of  a  steel  cored  cable  as  used  ott 
transmission  lines  may  be  obtained  by  taking  the  resist- 
ance as  equal  to  that  of  the  core  and  the  outer  conduc- 
tors connected  in  parallel,  and  by  taking  the  reactance 
as  equal  to  that  of  a  non-magnetic  cable  of  the  same 
outside  diameter.  The  direct-current  resistance  of  the 
steel  core  should  not  be  used,  but  only  the  value  of  the 
resistance  to  alternating  current. 


A^IJM^'cat) 


R.  W.  OVVKNS 


Soo®(l 


?/ 


THE  CHOICE  of  a  suitable  adjustable  speed 
motor  for  any  application  depends  upon  so  many 
factors  that  a  proper  selection  can  be  made  only 
by  comparison  of  all  these  factors.  In  power  plants, 
for  example,  both  alternating  and  direct-current  sup- 
plies are  often  available  and  sometimes  even  both  115 
and  230  volt  direct-current  powder.  In  such  cases, 
where  adjustable  speed  motors  having  speed  ranges  of 
about  2  to  I,  are  required  for  driving  small  pumps, 
blowers,  stokers  or  similar  equipment,  any  one  of  the 
following  schemes  of  speed  control  may  be  used  :• — 
Direct-Current  Motors — 

I — Shunt  field  control 

2 — Armature  resistance  control 

3-^Amature  voltage  control 


-I30O 

-1100 
-600 

- 

s 

a.^00 

1 

L-H 

*=: 

r^" 

R_p 

_ 

/ 

- 

^# 

/ 

-500 

—100 

/ 

/ 

etfcy 

— 

S400 

^  i.i 

y 

^- 

'^^ 

-" 

7 

'^ 

^^ 

CL 

</ 

/ 

/ 

H 

)rse-l 

ower 

Loo 

I 

' 

/ 

^ 

f' 

s 

// 

/ 

^ 

^' 

' 

1-200 

s 

^0 

,' 

/ 

A 

■^^ 

; 

/ 

' 

.j'^ 

^' 

■' 

1 

. 

/ 

/ 

K 

f>' 

1 

; 

^-^ 

^ 

575 
.1150 

- 

— 

R.pkj. 

, 

i^ 

r 

1 

r 

»       75      100     IJS     1 
1           '  Amfferes 

0 1 

3,p 

5     2io 

FIG.    I — TYPICAL  CURVES   FOR    MOTORS   WHEN    SPEED   IS   CHANGED   BY 
VARYING    THE   SHUNT   FIELD 

Alternating-Current  Motors — 

1 — Secondary  resistance  control 

2 — Pole  change. 

There  are  other  methods  of  obtaining  adjustable 
speed,  such  as  the  single-phase  commutator  motor  and 
the  induction  motor  with  different  applied  frequencies, 
which  are  suitable  for  certain  applications.  Only  the 
schemes  listed  above,  which  are  more  common  and 
more  generally  applicable,  will  be  considered  here. 

For  applications  of  this  type,  and  with  the  possi- 
bility of  choosing  any  one  of  these  methods  of  obtain- 
mg  an  adjustable  speed  drive,  the  question  of  the  rela- 
tive efficiency  of  the  different  methods  immediately 
arises.  Data  on  efficiency  at  the  normal  speed  is 
usually  available  or  easily  obtainable   for  the  motors 


that  w  ould  be  used  for  any  of  these  methods  of  speed 
adjustment.  It  is  impossible  to  give  data  of  the  effect 
on  efficiency  of  speed  increase  or  reduction  of  speed, 
which  would  be  applicable  to  motors  of  all  makes.  It 
is  possible  however  to  arrive  at  a  few  simple  rules  for 
estimating  with  fair  accuracy  the  efficiency  for  any 
speed  change  on  any  motor.  Though  these  rules  are 
derived  from  the  most  fundamental  relations,  their  de- 
rivation will  be  reviewed  in  order  to  point  out  the  de- 
viation from  the  fundamental  rule  in  the  case  of 
actual  machines. 

DIRECT-CURRENT  MOTORS  WITH   SHUNT  FIELD  CONTROL 

The  torque  of  a  direct-current  motor  is  directly 
proportional  to  the  product  of  field  strength  and  arma- 
ture current.  The  speed  of  a  direct-current  motor  is  in- 
versely proportional  to  the  field  strength.  Therefore,  if 


—100 

. 

-^ — ' 

1 

1 

iH^ 

■ — -Saas 

y_ 

i 

■ 

■^ 

1 

\ 

! 

\^ 

"'^^ 

^ 

S: 

^ 

^ 

N 



> 

,   . 

—80 

/^ 

^^^ 

■^ 

^ 

^ 

1::^ 

^ 

,, 

^/ 

■^ 

^ 

^ 

s/^'"'i 

N 

s 

>^ 

ill]        ! 

^i^^ 

dFfc-J 

/i        1                           .^J^ 

pr  \/ 

^0 

^ 

^ 

'       i        i       .^ 

/ 

-.0 

'        '>^ 

/ 

/ 

.K,  =  4 

^1 

/ 

/  , 

1 

1  *  * 

1          1      T<in,u. 

1       ?       lb       IS       .'i 

FIG.   2 — SPEED-TORQUE  CURVE  OF  AN   INDUCTION   MOTOR 

Assuming  the  rotor  resistance  constant,  and  no  primary  re- 
sistance or  magnetic  leakage. 

the  speed  of  a  motor  is  increased  by  weakening  the  field, 
the  armature  current  must  increase  in  direct  proportion 
to  the  speed  in  order  to  maintain  constant  torque. 
Horse-power  is  directly  proportional  to  the  product  of 
torque  and  speed,  so  that  the  horse-power  output  of 
such  a  motor,  with  torque  remaining  constant,  in- 
creases directly  with  the  speed.  Assume  a  40  hp,  575 
to  1 150  r.p.m.  shunt  wound  motor  driving  a  load  which 
requires  40  hp  at  1150  r.p.m.,  the  load  being  of  such  a 
nature  that  the  torque  required  to  drive  it  is  -the  same 
at  all  speeds.  To  reduce  the  speed  of  this  motor  to  575 
r.p.m.  requires  that  the  field  strength  be  doubled.  With 
this  doubled  field  strength  only  one  half  the  armature 
current  will  be  required  to  develop  the  same  torque  at 
575  r.p.m.  as  was  developed  at  11 50  r.p.m.     From  the 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


fact  that  the  same  torque  is  developed  at  one-half  speed, 
it  is  apparent  that  the  horse-power  output  at  575  r.p.m. 
is  20  hp.  If  the  efficiency  curves  of  this  motor  were  the 
same  at  all  speeds,  the  efficiency  for  any  speed  reduc- 
tion with  constant  torque  load  could  be  obtained  by 
reading  efficiency  at  a  load  obtained  by  reducing  the 
load  at  maximum  speed  in  direct  proportion  to  the  re- 
duction of  speed. 

For  a  direct-current  motor  with  speed  adjustment 


slightly  with  increased  speed,  so  that  for  any  load  the 
efficiency  at  the  high  speed  is  lower  than  the  efficiency 
at  the  low  speed.  This  change  in  efficiency  is  relatively 
small  however.  Fig.  i  shows  calculated  efficiency 
curves  for  a  40  hp,  575  to  11 50  r.p.m.  motor.  These 
curves  are  typical  for  this  class  of  motors  and  will  serve 
as  a  guide  for  estimating  efficiency  when  speed  is 
changed  by  varying  the  shunt  field  strength,  the  effi- 
ciency curve  at  one  speed  being  known. 


TABLE  I — EFFECT  OF  SPEED  REDUCTION  BY  ARMATURE  RESISTANCE 


Shunt   Motor 


Compound  Motor 


Series  Motor 


Torque — lb.   ft. 
R.  p.  m 


Hp. 

Amperes 

F.  &  W.  losses — watts. 

Iron  loss — watts 

Shunt   loss — watts 

I  ^'  R  losses — watts 

Total  losses — watts.  .  .  . 

Input — watts 

Output — watts 

Efficiency — per  cent .  .  . 
Estimated   efficiency... 


40 
145 
640 
1040 
380 
1450 
3510 


575 
20 
143.5 
270 
410 
380 

17  020 

18  080 
33  000 
14  920 

45.1 
44.8 


1160  575 
10.2  5.04 
42.1 

640 

880 

380 

170 
2070 
9680 
7610 
78.6 


40.5 

270 

320 

380 

4590 

5560 

9320 

3760 

40.3 

39 


145 
640 
1040 


575 
20 
143.5 
270 
410 
230 

17  170 

18  080 
33  000 
14  920 

45.1 
44.8 


46 

1300 

11.4 

46.8 

770 

1060 

230 

230 

2290 

10  790 

8500 

78.8 


46 

575 

5.04 

44.9 

270 

320 

230 

5750 

6570 

10  330 

3760 

36.4 

35 


144.9 
640 
1040 

iaio 

3490 
33  330 
29  840 


143.5 
270 
410 

17  466 

18  080 
33  GOO 
14  920 

45.1 
44.8 


64.5 
1230 
1600 

"436 

3260 

14  820 

11  560 

77.9 


10  000 

10  610 

14  370 

3760 

26.2 

25.3 


by  shunt  field  control,  the  efficiency  curves  at  different 
speeds  are  not  quite  identical,  because  part  of  the  losses 
in  the  motor  vary  with  the  speed.  The  armature,  com- 
mutating  field,  and  series  field  PR  losses  obviously  are 
independent  of  the  speed,  but  friction  and  windage 
losses,  iron  loss  and  shunt  field  PR  loss  change  with 
speed.  The  friction  losses  increase  about  directly  with 
the  speed,  and  windage  losses  increase  roughly  as  the 
second  power  of  the  speed.  The  shunt  field  PR  loss  de- 
creases as  the  speed  increases.  Its  rate  of  decrease  de- 
pends upon  the  degree  of  saturation  of  the  iron  which, 
in  turn,  changes  as  the  speed  increases,  so  that  as  higher 
speeds  are  reached  this  loss  decreases  directly  as  the 
speed  increases. 

The  change  of  iron  loss  with  change  of  speed  is 
complicated  by  the  effect  of  field  distortion,  so 
that,  for  one  design  of  motor,  it  may  decrease  with  in- 


DIRECT-CURRENT   MOTOR   WITH   ARMATURE  RESIST- 
ANCE CONTROL 

If  the  field  strength  of  a  direct-current  motor  is 
kept  constant  and  the  voltage  applied  to  the  armature  is 
varied,  the  speed  of  the  motor  will  change  very  nearly 
in  proportion  to  the  change  of  applied  voltage.  The 
speed  of  a  motor  may  then  be  adjusted  by  applying  dif- 
ferent voltages  to  the  armature  or,  as  is  the  more  usual 
procedure,  since  only  one  voltage  is  generally  available, 
by  inserting  resistance  in  series  with  the  armature  so 
that  part  of  the  line  voltage  is  lost  in  IR  drop  in  the  re- 
sistance and  the  remainder  is  available  at  the  armature 
terminals.  Torque  being  proportional  to  field  strength 
and  armature  current,  if  the  field  strength  remains  con- 
stant and  speed  is  changed  by  armature  control,  the 
armature  current  will  change  directly  as  the  torque 
changes.     For  a  constant  torque  load,  therefore,   the 


TABLE 

II— EFFECT  OF 

SPEED 

REDUCTION  BY 

CHANGE  OF  VOLTAGE 

Shunt 

Motor 

Compound  Motor 

Series 

Motor 

1S3 

1150 

40 

143.4 

230 

640 

1040 

380 

1450 

3510 

33  350 

29  840 

89.5 

183 

575 

20 

141.9 

120.1 

270 

410 

380 

1430 

2490 

17  410 

14  920 

85.6 

46 

1160 

10.2 

40.5 

230 

640 

880 

380 

170 

2070 

9680 

7610 

78.6 

46 

575 

5.04 

38.9 

116.2 

270 

320 

380 

160 

1130 

4890 

3760 

77 

183 

1150 

40 

144 

230 

640 

1040 

230 

1600 

3510 

33  350 

29  840 

89.5 

183             46 

575         1300 

20         11.4 

142.5         45.8 

120.5           230 

270           770 

410         1060 

230           230 

1580            230 

2490         2290 

17  410      10  790 

14  920         8500 

85.8         78.8 

46 

575 

5.04 

43.9 

103.8 

270 

320 

230 

210 

1030 

4790 

3760 

78.6 

183 

1150 

40 

144.9 

230 

640 

1040 

isio 

3490 
33  330 
29  840 

89.6 

575 
20 
143.5 
121.1 
270 
410 

1770 

2450 

17  370 

14  920 

86 

1770 
15.5 
64.5 
230 
1230 
1600 

'iso 

3260 
14  620 
11560 

77.9 

575 

5.04 

62.6 

76.6 

270 

340 

'iib 

1020 
4780 
3760 

78.7 

Hp 

Efficiency — per  cent 

creasing  speed  while  for  another  design  it  may  increase. 
The  general  tendency  is  the  latter,  but  for  moderate 
ranges  of  speed  adjustment,  that  is  ratio  of  speeds  up 
to  about  2  to  I,  the  increase  of  iron  loss  is  quite  small. 
With  friction,  windage  and  iron  losses  increasing  and 
shunt  field  loss  decreasing  with  increasing  speed,  it  is 
apparent  that  the  nature  of  the  change  in  the  sum  of 
these  losses  depends  upon  their  relative  magnitudes. 
For  the  usual  types  of  commercial  motors  with,  say,  2 
to   I    speed   range,  the  sum  of  these  losses  increases 


armature  current  will  remain  constant  for  all  speeds. 
For  such  a  load,  if  speed  is  changed  by  inserting  resist- 
ance in  series  with  the  armature,  the  total  applied  volt- 
age is  constant,  the  current  is  constant,  therefore  the 
total  motor  input  is  constant.  Output,  however,  being 
the  product  of  torque  and  speed,  decreases  directly  with 
speed.  The  efficiency  of  a  motor  driving  a  constant 
torque  load  with  this  type  of  control,  therefore,  de- 
creases in  direct  proportion  to  the  decrease  of  speed. 
This  rule  also  applies  when  torque  changes  with  speed. 


January,  192 1 


THE  ELECTRIC  JOURNAL 


13 


Suppose  that  the  torque  decreases  as  the  speed  de- 
creases, then  the  input  decreases  with  the  decrease  in 
torque  while  the  output  decreases  with  the  decrease  in 
torque  and  also  with  decrease  in  speed.  The  ratio  of 
output  to  input,  or  efficiency,  then  still  decreases  di- 
rectly as  the  speed,  or  the  efficiency,  when  developing 
any  torque  at  reduced  speed,  is  equal  to  the  efficiency 


FIG.    3 — PERFORMANCE  CURVES    FOR   A   4O   HP,   SIX-POLE 
INDUCTION  MOTOR 

when  developing  the  same  torque  at  full  armature  volt- 
age times  the  ratio  of  reduced  speed  to  the  speed  at  full 
armature  voltage. 

In  the  foregoing  discussion  the  effect  of  friction, 
windage  and  iron  losses  has  been  neglected.  However, 
if  these  losses  vary  directly  as  the  speed,  the  rule  given 
will  still  be  exact.  In  a  motor  whose  speed  is  adjusted 
by  armature  resistance,  these  losses  do  vary  almost 
directly  as  the  speed.  Table  I  gives  calculated  losses 
for  40  hp,  1 150  r.p.m.  shunt,  series  and  compound 
wound  motors  with  speed  reduced  to  575  r.p.m.  for  a 
constant  torque  load  and  also  for  a  load  where  torque 
changes  as  the  second  power  of  the  speed.  For  this 
table  a  motor  has  been  assumed  with  relatively  large 
friction,  windage  and  iron  losses,  yet  it  will  be  observed 
that  the  rule  holds  closely,  especially  where  the  speed 
reduction  is  approximately  50  percent. 

DIRECT-CURRENT   MOTOR  WITH   ARMATURE 
VOLTAGE  CONTROL 

Where  means  are  available  for  changing  the 
applied  voltage  without  inserting  resistance  in  series 
with  the  armature,  the  speed  decreases  nearly  in  propor- 
tion to  the  decrease  in  applied  voltage.  The  input  to 
the  motor  then  decreases  practically  with  the  decrease 
in  speed.  Since  the  output  decreases  with  speed  the 
efficiency  with  this  type  of  control  for  a  given  torque  at 
any  speed  reduction  is  the  same  as  the  efficiency  for 
that  torque  at  full  speed  or  the  efficiency  for  moderate 
speed  ranges  is  practically  independent  of  the  speed. 

The  conclusion  reached  in  the  above  paragraph  was 
based  on  the  assumption  that  the  speed  of  a  motor  de- 


creases directly  with  the  decrease  of  voltage  applied  to 
the  armature.  Actually  the  speed  decreases  directly 
with  the  decrease  of  counter-electromotive-force. 
Analysis  of  the  difference  between  the  assumed  condi- 
tions and  the  actual  conditions  shows  that  it  was 
assumed  that  the  variable  PR  losses  decrease  with 
speed  while  they  actually  remain  constant  for  a  given 
torque.  Also  the  effect  of  iron  losses,  friction  and 
windage  and  shunt  field  losses  was  neglected.  Table 
II  shows  calculated  efficiencies  for  the  same  motors  as 
in  Table  I  except  that  the  speed  is  adjusted  by  changing 
the  voltage  applied  to  the  armature.  Table  II  shows 
that,  for  a  given  torque,  the  efficiency  decreases  some- 
what as  the  speed  is  decreased  by  armature  voltage  con- 
trol. 

INDUCTION    MOTOR    WITH    SECONDARY    RESIST- 
ANCE CONTROL 

In  an  induction  motoi,  just  as  in  a  direct-current 
motor,  the  torque  developed  is  proportional  to  the  pro- 
duct of  field  strength  and  armature  current;  or  to  use 
the  terms  ordinarily  applied  to  an  induction  motor,  tor- 
que is  proportional  to  the  product  of  primary  flux  and 
secondary  current.  When  running  at  synchronous 
speed  the  rotor  conductors  rotate  with  the  stator  field 
and  do  not  cut  the  stator  flux.  At  synchronous  speed, 
therefore,  no  voltage  is  induced  in  the  rotor,  no  current 
flows  in  the  rotor,  and  consequently  no  torque  is  de- 
veloped. To  develop  torque,  therefore,  it  is  necessary 
for  the  rotor  to  run  at  a  speed  less  than  the  speed  of 
the  rotating  stator  field.  The  flux  cut  by  the  rotor  con- 
ductors and  the  rotor  voltage  induced  is  then  propor- 
tional to  the  difference  in  speed  between  rotor  and 
stator  field,  or  to  the  slip.  If  the  rotor  resistance  were 
constant,  assuming  no  primary  resistance  or  magnetic 


FIG.    4 — PERFORMANCE    CURVES    FOR    THE    40    HP    INDUCTION    MOTOR 
WITH   TWELVE-POLE  STATOR  CONNECTIONS 

leakage,  the  rotor  current  and  consequently  the  torque 
would  be  proportional  to  the  slip,  or  the  speed-torque 
curve  of  an  induction  motor  would  have  the  form 
shown  at  a  in  Fig.  2.  If  the  secondary  resistance  of  this 
motor  was  doubled,  to  develop  a  given  torque  would  re- 


14 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


quire  twice  the  secondary  voltage  or  twice  the  slip  re- 
quired under  the  conditions  for  curve  a.  The  speed- 
torque  curve  for  this  resistance  would  be  that  shown 
at  b. 

In  an  actual  induction  motor,  primary  resistance 
and  magnetic  leakage  alter  the  shape  of  the  speed-tor- 
que curves.  Instead  of  the  curves  a  and  b,  an  actual 
motor  will  have  curves  of  the  form  shown  at  c  and  d. 
However,  in  the  actual  motor  the  slip  at  any  torque  is 
still  directly  proportional  to  the  secondary  resistance  as 
shown  by  curves  c,  d,  and  e.  The  same  current  and 
power-factor  curves  apply  for  all  three  speed-torque 
curves.  For  a  given  torque,  then,  the  speed  of  an  in- 
duction motor  may  be  reduced  by  increasing  the  rotor 
resistance   without   aiTecting   the   power-factor   or   pri- 


— 80 

1 

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FIG.    S — STE.-\M    CONSUMPTION   OF    NON-CONDENSING   TURBINE 

mary  current.  For  an  induction  motor  with  speed  con- 
trol by  rotor  resistance  driving  a  constant  torque  load, 
the  input  at  reduced  speed  is  equal  to  the  input  at  full 
speed,  and  the  output  has  decreased  with  the  speed. 
The  efficiency  at  tlie  low  speed  then  is  equal  to  efficiency 
at  full  speed  multiplied  by  the  ratio  of  the  low  speed 
to  full  speed.  This  case  is  the  same  as  a  direct-current 
motor  with  speed  controlled  by  armature  resistance. 
Just  as  with  the  direct-current  motor,  if  the  torque 
changes  with  the  speed,  the  efficiency  at  the  reduced 
speed  is  equal  to  the  efficiency  when  developing  the  low- 
speed  torque  at  full  speed,  multiplied  by  the  ratio  of 
low  speed  to  full  speed. 

INDUCTION    MOTOR    WITH    POLE    CHANGE    CONTROL 

In  an  induction  motor,  speed  may  be  changed  by 
changing  the  number  of  primary  poles.  In  general, 
only  two  combinations  of  poles  are  practicable.  This 
arrangement,    therefore,    gives    only   two   fixed    speeds 


with  no  adjustment  between  these  fixed  speeds.  For 
example,  a  6o  cycle  motor  may  be  wound  so  that  its 
primary  coils  can  be  connected  to  give  six  poles  with  a 
corresponding  speed  of  approximately  ii6o  r.p.m.,  also 
the  primary  connections  can  be  changed  to  give  twelve 
poles  with  a  speed  of  about  570  r.p.m.  This  arrange- 
ment gives,  in  reality,  two  motor  designs  for  the  same 
full-load  torque,  the  high-speed  motor  having  twice  the 
full-load  horse-power  that  the  low-speed  motor  has. 
For  the  same  torque,  it  is  to  be  expected  that  the  effi- 
ciency and  power-factor  would  be  somewhat  reduced 
with  the  low-speed  connection.  However,  when  two 
pole  combinations  are  obtained  with  the  same  primary 
winding,  both  of  these  combinations  cannot  be  equally 
effective.  The  primary  winding  is  so  designed  as  to  be 
reasonably  satisfactory  for  the  small  pole  combination 
and,  therefore,  it  is  a  winding  of  relatively  high  resist- 
ance and  reactance  in  proportion  to  its  effectiveness 
when  used  for  the  large  pole  combination.  The  effi- 
ciency and  power-factor  at  the  low  speed  therefore, 
are  considerably  lower  than  at  the  high  speed  for  the 
same  torque  at  botli  speeds.  Fig.  3  shows  performance 
curves  for  a  40  hp,  six-pole  motor,  and  Fig.  4  shows 
curves  for  the  same  motor  with  twelve-pole  stator  con- 
nections. 

SMALL  STEAM  TURBINES 

When  steam  is  available  for  power,  a  choice  of  the 
most  efficient  type  of  drive  cannot  be  made  without  con- 
sidering the  small  steam  turbine.  In  Fig.  5  curves  a 
and  b  give  the  steam  consumption  of  a  non-condensing 
turbine  of  about  40  hp.  Curve  a  represents  steam  con- 
sumption with  two  nozzles,  and  curve  b  is  the  steam 
consumption  with  one  nozzle.  These  curves  are  approxi- 
mately correct  for  small  ranges  of  speed  adjustment. 
Where  a  turbine  of  this  type  can  be  used,  the  total 
steam  consumption  of  the  main  plant  probably  is  about 
18  pounds  per  kilowatt-hour.  Allowing  an  efficiency  of 
84  percent  for  intermediate  equipment,  as  transformer 
and  motor-generator  set,  a  steam  rate  of  21.5  pounds 
per  kilowatt-hour  or  16  pounds  per  hp-hour  is  obtained 
for  power  delivered  to  the  terminals  of  a  direct-current 
motor.  A  motor  with  90  percent  efficiency,  taking 
power  from  the  main  plant  then  will  use  17.8  pounds  of 
steam  per  hp-hr.  delivered.  Comparing  this  figure  with 
curves  o  and  b  Fig.  5,  it  appears  that  an  efficient  motor 
drive  is  much  more  economical  than  a  small  turbine 
drive. 

This  is  not  the  case,  however,  when  the  exhaust 
steam  from  the  turbine  can  be  used  for  feed  water  or 
general  heating.  Curve  C  Fig.  5  S'^es  approximately 
the  steam  consumption  of  the  small  turbine  when  the 
turbine  is  credited  with  the  total  heat  of  the  exhaust 
steam.  Comparing  this  curve  with  the  figure  of  17-8 
pounds  per  hp-hour  for  the  motor  drive,  it  is  apparent 
that  the  small  steam  turbine  drive  may  be  much  more 
economical  than  a  motor  drive  where  a  large  part  of 
the  exhause  steam  can  he  used. 


se  Traiii^form-aiioi^  ¥ 


Thrctj 


I  v/o 


rUroe-'W^re 


E.  P.  WIMMER 

Transformer  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


IN  TRANSFORMING  from  three-phase  to  two- 
phase  with  Scott-connected  autotransformers,  it  is 
often  desirable  to  obtain  a  two-phase  three-wire  sys- 
tem instead  of  a  two-phase  four-wire  system.  The 
two-phase  four-wire  system  has  been  thoroughly  dis- 
cussed by  Mr.  E.  G.  Reed.*     A  different  connection  is 


r 

J       r,              E 

M 

ain  Autotransformer     r     '■* 

F.                      ^       , 

FIG.     I — WHERE    THE 
TWO-PHASE  VOLTAGE  IS 
LESS    THAN    122.5    PER- 
CENT   OF    THE    THREE- 
PHASE    VOLTAGE 


A  B 

FIG.     2 — WHERE    THE 

TWO-PHASE  VOLTAGE  IS 

GRE.IlTER  than    I22.S 

PERCENT  OF  THE 

THREE-PHASE    VOLTAGE 


The  current  in  the  remaining  part  of  the  main 
autotransformer  is  /„.  The  sum  of  the  products  of  the 
voltage  and  the  current  in  the  two  parts  of  the  main 
autotransformer  winding  gives  its  kv-a  rating  as  fol- 
lows : — • 
Kv-a  of  main  autotransformer  ^  E,  ht  +  (1414  £1 Et)  It 

=  /t^i  -to  -^  I  -f  1.333  ^y—  2.23  -£- 

-I-  1.414  £.  —  £.  i  (,) 

The  total  kv-a  transformed  =  sE,  I,  .   (5) 
Then, — 
Af-o  of  main  autotransformer 

Kv-a  transformed  ~ 

•^•■i    I  1-333  2I3  ^i 


G 

-E, , 

L 

r| 

Teaser 

Auto 

transformer 

1^ 

(J 

\ 

^'VAVV^A^ 

%J 

1    Main 

Au 

totransformer    ] 

1^ 

- 

rI 

E^ 


FIG.    3 — WHERE    THE 
TWO-PHASE  VOLTAGE  IS 
LESS  THAN  70  0  PER- 
CENT OF  THE  THREE- 
PHASE    VOLTAGE 


0-5 


(<5) 


necessary  for  the  two-phase  three-wire  system. 
are  three  cases  to  be  considered. 


There 


I WHEN   THE  TWO-PHASE  VOLTAGE   IS  LESS   THAN    122.5 

PERCENT   OF   THE   THREE-PHASE  VOLTAGE 

Fig.  I  shows  the  autotransformers  connected  for 
this  transformation.  A  condition  of  balanced  load  is 
assumed  in  order  to  simplify  the  problem.  In  deter- 
mining the  kv-a  rating  of  the  autotransformers  it  is 
necessary  to  know  the  currents  in  the  various  parts  of 
the  winding.  The  currents  whose  values  are  not  ob- 
vious, are  la  and  /fb-     From  Fig.  i, — 

Iti  =:  Ia>  -\-   /aA 

The  phase  relations  of  these  currents  are  shown 
in  Fig.  4,  and  the  numerical  value  i-', — 

/rd  =  (0.707  h  —  0.866  U)  +  j  (0.707  I2  —  0.5  h)  . 
The  next  step   is  to   secure  an  ex- 
pression for  /j  in  terms  of  /, : — 
Kv-a  transform ed 

2£= 

Kv-a  transformed 
1-732  £. 
Combining  these  equations  gives, — 
2  £2 


I'  rem  Fig.  2, — 

/fb    =     I.4I4    /;  _  /, 

=  l'{    1-414—  1-154  Y.) 
Therefore, — 

Kv-a  of  teaser  =  0.707  /rt  £=  -f-  /.  (0.866  £, 

=  a(^£,-  1.632  g-) 


(7) 

0.707  El) 


and  Kv-a  of  tease. 


teaser  (  £,  \ 


Kv-a  transformed    =  ^  -  o.v>iO  -^  J (*) 

Equations  (6)  and  (8)  give  the  total  kv-a  rating 
of  the  autotransformers,  and  to  put  them  on  the  same 
basis  as  for  a  two-winding  transformer,  the  expressions 
must  be  divided  by  two.  The  equations  then  become, — 
kv-aof  parts  required  for  main  unit 


Kv-a  transformed 


/■:■ 


I  1-333 


(o 


2-23        I     ,  £, 

£717+ £7+ °-7°7  -  °-s  IT 

Kv-a  of  parts  required  for  teaser 
Kv-a  transformed 


=  4^(i-o.8i6|;) 


-  (9) 

(/o) 


I2  = 


/. 


(^) 


1.732  £1     ' 

Substituting  this  value  in  equation 
(i)  gives, — 

/m  =  h  1(0.707  —    £;)  +  ;'(  (0.707 


FIG.   4 — PHASE  RELA- 
TIONS  FOR  THE  CON- 
NECTIONS SHOWN  IN 
FIG.    I 


FIG.    5— PHASE  RELA- 
TIONS  FOR  THE  CON- 
NECTIONS SHOWN  IN 
FIG.   2 


FIG.  6 — PHASE  RELA- 
TIONS  FOR  THE  CON- 
NECTIONS SHOWN  IN 
FIG.  3 


0.577  ~|)] 


=  /.  -yi  (  0.707  —  £■  )  -1-  (0.707  -  0.577  g;  ) 


£2= 


£. 

2-2^  £7' 


/r..   =  /,    •y   I  +    1.333  £T 

*In  the  Journal  for  May,  1919,  p.  216. 


(J) 


Example : — What  is  the  ratio  of  the  kv-a.  rating 
of  the  transformer  parts  required  to  the  kv-a.  trans- 
formed, for  a  ratio  of  transformation  of  440  volts 
three-phase  to  440  volts  two-phase  three-wire? 

For  this  case-v:-^^  i  and  from  equation  (9), — 


i6 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


Kv-a  of  parts  required  for  main  unit 
Kv-a  transformed 


=  o.i8i 


0.816 


)=o< 


-Ji.333  —  2.23  -f  I  +  0.707  - 

Also,  from  equation  (10), — 

Kv-a  of  parts  required  for  teaser i_  / 

Kv-a  transformed  2    \ 

II — WHEN    THE    TWO-PHASE    VOLTAGE    IS    GREATER    THAN 
122.5  PERCENT  OF  THE  THREE-PHASE  VOLTAGE 

Fig.  2  shows  two  autotransformers  connected  for 
this  condition.  An  inspection  of  this  figure  and  Fig.  5 
will  make  apparent  that  the  conditions  relating  to  the 

TABLE  I— COMPARISON  OF  PERCENTAGES  OF  KV-A 

PARTS  REQUIRED 

For  the  Two-phase,  Three-wire  and  Two-phase,  Four-wire 

Systems 


£. 
£2 

Percentages  for 
Main 

Percentages  for 
Teaser 

Total  Percentages 

Two-phase, 
Three-wire 

11 

II 

0.2 
0.4 
0.8 

I.O 

30 
50 

48.30 
32.65 
12.10 
18.40 
48.00 
54-40 

4330 
3340 
18.34 
14.42 
38.70 
44.60 

41.85 
3370 
17.40 
9.20 
29.60 
3775 

38.46 
26.90 
3.80 
6.70 
35-55 
41-35 

90.15 
66.35 
29.57 
27.60 
7760 
92.15 

81.76 
60.30 
22.14 
21.12 
74-25 

85-95 

main  autotransformer  are  the  same  in  this  case  as  in 
Case  I,  but  are  different  for  the  teaser, 
/fg  =  /.  —  1. 414  1 2 
Kv-a  of  teaser  autotransformer  = 

0.866  /fg  E,  +  1.414  A  (0.707  E,  —  0.866  E.) 
Substituting  the  value  of  /,  from  equation  (2), — 

Kv-a  of  teaser  auto  =  I,  {zE,  —  2.45  E,)  (//) 

By  the  use  of  equation  (5), — 

Kv-a  of  teaser  Et  .,,, 

„ H — 1 J      ^  I  —  1.225 -p-   (IS) 

Kv-a  transformed  -"  £1 

Putting  this  relation  on  the  same  basis  as  for  a  two 
winding  transformer  it  becomes, — 

Kv-a  of  parts  required  for  teaser i_  /  £1 

Kv-a  transformed  2    \'  '  E, 

Example :— What  is  the  ratio  of  the  kv-a.  rating  of 

the  transformer  parts  required  to  the  kv-a.  transformed, 

for  a  ratio  of  transformation  of  220  volts  three-phase  to 

440  volts  two-phase? 

E. 
For  this  case-=—  =  2  and  from  equation  (9), — 

Kv-a  of  parts  required  for  main  unit 

Kv-a  transformed  ~ 


l^)U3) 


—  V    1-333  —  I-I15  +  0.25  -f  0.3535 
And  from  equation  (13) 
Kv-a  of  parts  required  for  teaser 


0.125  =  0.40 


=t(. 


1.225X 


o.5J  =  o.: 


Kv-a  transformed 

III WHEN  THE  TWO-PHASE  VOLTAGE  IS  LESS  THAN  JO.J 

PERCENT  OF  THE  THREE-PHASE  VOLTAGE 

From  Fig.  3,  which  shows  the  conne  ctions  for  this 
condition,  and  Fig.  6  which  shows  the  phase  relations  of 
the  currents,  it  is  apparent  that  /fa  has  the  same  value 
as  in  Case  I.     Therefore, 


kv-a  of  main  autotransformer  = 

1.414  £>  /f.  +  (£•  —  1.414  £,)  U 
Or,  referring  to  equation  (2),  and  using  /(„  in  place  of 
Iti  in  equation  (3), —  ' 
Kv-a  of  main  autotransformer  =  2  £2  Z,  X 


0.707  £: 


N£? 


1333 

£.' 


2.23 

£.£. 


+  0.577  —  0.816   ^ 


Using  equation  (5),  and  changing  the  equation  to 
the  same  basis  as  a  two-winding  transformer, — 
Kv-a  of  parts  required  for  main  unit 

Kv-a  transformed  ~ 


1-333  E' 


2^3E, 
E, 


-+  0.577  —  0.816  -^'  \U4) 


In  this  case,  the  conditions  relating  to  the  teaser 
transformer  are  the  same  as  in  Case  I. 

Example : — What  is  the  ratio  of  the  kv-a.  rating  of 
the  transformer  parts  required  to  the  kv-a.  transformed, 
for  a  ratio  of  transformation  of  440  volts  three-phase  to 
220  volts  two-phase  ? 

£2 

For  this  case  -=-=  0.5  and  from  equation  (14), — 

Kv-a  of  parts  required  for  main  unit 

Kv-a  transformed  ~ 


'i-f--- 


+  0.577  —  0.408 


=  0.25 


.707  \i.       4 

And  from  equation  (10), — 
Kv-a  of  parts  required  for  teaser         i     /  ■'""''     ~"    \ 
Kv-a  transformed  =  -7  \^  I  -  O.414  J    =0.203 

Fig.  7  shows  the  variation  of  the  kv-a.  of  trans- 
former parts  required  to  the  kv-a.  transformed,  for  both 


-aso 

U- 

1 — 

-0A» 

} 

>^ 

^ 

n 

S 

s 

\ 

/ 

-aw 

-0)J 

H 

\ 

s\ 

/ 

i 

\ 

'  V 

p»j 

«^ 

" 

s— 

^ 

w* 

1 

\J 

/ 

-0.J4 

3 

(\ 

h. 

/ 

•5 

\\ 

^„ 

/ 

/\ 

-0.16 

5 

/ 

\   ^ 

K 

/' 

/ 

3 

/ 

\v 

X 

\ 

'oj 

f 

> 

l^ 

\ 

\ 

\ 

\ 

\ 

s 

0 

{ 

' 

' 

Ratio  of  gi 

FIG.    7— EFFECT   OF   VOLTAGE    RATIO   ON    TRANSFORMER   CAPACITY 
REQUIRED 

The  ordinates  represent  the  ratio  of  kv-a  of  parts  required  to 
kv-a  transformed. 

the  main  and  teaser  autotransformers,   for  ratios  of 

£ 
transformation  cT^ ranging  from  o.i  to  6.     Table  I  gives 

a  comparison  of  the  percentages  of  the  kv-a.  of  trans- 
former parts  required  to  the  kv-a.  transformed,  for  the 
two-phase  three-wire  and  the  two-phase  four-wire  sys- 
tems. 


/X^iilcutlom  €)if  Steam  Coniloiii^tir^-II 


Seieciion  of  sSize 

F.  A.  BURG 


THE  SUBJECT  of  condenser  selection  from  the 
standpoint  of  economics,  has  received  less  con- 
sideration than  it  deserves.  An  improper  choice 
■of  the  size  of  the  condensers  in  a  plant  may  cost  thou- 
sands of  dollars  each  year.  Time  spent  in  the  selection 
of  condensers  is  time  well  spent  as  thereby  such  losses 
can  be  prevented.  To  assist  in  a  clearer  understanding- 
of  the  problem,  the  general  procedure  to  follow,  to- 
gether with  specific  examples,  are  discussed  in  the  fol- 
lowing article. 


8       .. 

^ 

/ 

\ 

■a 

/ 

s 

3 

/ 

s 

g 

/ 

\ 

s 

/ 

\ 

^ 

/ 

\ 

,!! 

/ 

\, 

1 
1— . 

s 

e    , 

\ 

L 

\ 

\ 

S 

V 

1 

\ 

\ 

8Q 

» 

DO 

.JT.. 

" 

000 

n 

boo 

u 

b66 

Cone 

QalloD 

per  A 

inute 

gallons  per 
of  steam.  .  .  . 
water 


2  Total  lbs 

:!  Vac.    75° 

■1  Improvt'inont   in   vacuum.. 

n  Per  cent  corr.  at  5%    per 

0  Sav.  lbs.  of  steam  per  hr. . 

7  Sav.  ]J>s.  of  steam  per  yr. . 

8  Cost  of  steam 

9  Cost  cap.  at  15  per  cent.  . 


FIG.    I — DETERMINING    MOST  ECONOMICAL   SIZE  OF  JET   CONDENSER 

The  problem  is  by  no  means  simple,  when  all  the 
factors  bearing  on  the  selection  are  taken  into  consid- 
eration. At  first  glance  it  would 
appear  that  the  size  of  the  con- 
denser can  be  determined  if  the 
vacuum  to  which  the  prime  mover 
can  effectively  expand,  the  amount 
of  steam  to  be  condensed  and  the 
temperature  of  the  cooling  water 
are  known ;  but  there  are  a  num- 
ber of  other  factors  that  must  be 
taken  into  account.  "Rules  of 
Thumb",  such  as  proportioning  the 
surface  to  the  kilowatt  rating  of 
the  main  turbine,  may  be  used  to 
obtain  an  approximate  size,  or  as  a 
tiasis  from  which  to  start  calcula- 
tions, yet  no  such  rule  has  been 
devised  that  will  apply,  except  in  a  general  way. 

The  condenser  should  not  be  chosen  for  one  speci- 

iic  temperature  of  cooling  water,  or  for  one  load  on  the 

vnrii-i  turbine,  but  for  the  average  temperature  and  the 

■■-.   -e    load    that    will    prevail    throughout    the    year. 

•  ■;     e  of  the  condenser  should  be  taken  into  account 


only  in  its  bearing  on  the  cost  of  producing  power,  for 
the  condenser  that  is  cheapest  in  first  cost  is  frequently 
the  most  expensive  to  operate. 

Considerable  data  on  various  sizes  of  condensers 
is  necessary  before  the  various  calculations  can  be 
made.  First,  estimate  the  average  load  on  the  turbine 
to  be  served  by  the  condenser.  This  is  most  conven- 
iently taken  on  a  yearly  basis,  estimating  the  total  num- 
ber of  hours  per  year  that  the  unit  will  be  in  service, 
making  sufficient  allowance  for  shut-downs,  and  then 
the  average  load  that  will  be  carried  while  the  unit  is  on 
the  line.  From  the  water  rates  of  the  turbine  the  aver- 
age steam  consumption  for  the  estimated  load  can  be 
calculated.  The  amount  of  steam  for  which  the  con- 
denser should  be  designed  is  thus  obtained. 

For  the  cooling  water  temperature,  the  average 
temperature  throughout  the  year  should  be  taken. 
Actual  statistics  are  preferable  in  arriving  at  the  aver- 
age, but  where  a  log  of  the  temperatures  is  not  available 
as  accurate  an  estimate  as  possible  should  be  made. 

The  power  required  to  drive  the  condenser  aux- 
iliaries is  an  important  item,  therefore  an  accurate  de- 
termination of  the  pumping  heads  is  essential.  The 
head  on  the  circulating  pump  of  a  jet  condenser  con- 
sists of  the  internal  head,  due  to  the  vacuum,  and  the 
external  head,  due  to  the  elevation  at  which  the  water 
is  discharged  and  the  pipe  friction.  This  is  also  true 
of  the  pumping  head  on  the  condensate  pump  of  a  sur- 
face condenser.  The  head  on  the  circulating  pump  of 
a  surface  condenser  consists  of  the  suction  lift  plus  the 


T.iBLK    I— CALCULATIONS   AND   ESTIMATES   FOR   JET   CONDENSKRS 


10  Hp.   for  drive 

11  Equiv.   steam 

12  Excess    steam 

13  E.xcess  steam   per  yr 

14  Cost  of  steam 

15  Cost  capitalized  at  15  per  cent 


Ifi   Maint.  per  yr 

17  E.xcess  maint 

18  Excess  maint.  cap. 


20  Excess 

21  Line    9- 


8000 

9000 

10  000 

100  000 

100  000 

100  000 

27.86 

28.0 

28.11 

0 

0.14 

0.25 

0 

0.70 

1.25 

0 

700 

1250 

0 

4  900  000 

8  750  000 

a 

$1715 

$3060 

0 

11  430 

20  400 

12  0001 

100  000 

28.26 
0.40 


13  000 

100  000 

23.32 

0.46 


260 

3170 

240 

10  000 


110001 

100  oool 

28.191 

0.331 

1.651 

16501  2000  2300 

1 1  550  000  14  000  000  16  100  000 

$40301  $49001  $5620 

26  900[  32  7001  37  400 


370 

4520 

1590 

11  130  000 

$3870 

25  800 


285 

315 

340 

3480 

3850 

4150 

550 

920 

1220 

3  850  000 

6  340  000 

8  540  000 

$1348 

$2220 

$2990 

9000 

14  800 

19  900 

5601 
1101 
7351 


6201 

1701 
1135] 


6751 
2251 
15001 


730 
280 
1870 


$41101   $46651    $19651 


discharge  head  (actual  number  of  feet  above  the  circu- 
lator to  which  the  water  is  carried)  plus  the  friction, 
including  pipe  friction  and  friction  inside  the  con- 
denser. In  cases  where  the  discharge  pipe  is  sealed, 
and  below  the  highest  point  in  the  circulating  system, 
some  allowance  can  be  made  on  the  total  pumping  head 


iS 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


lor  the  syphonic  effect.     The  power  required  to  operate     c'ucccl  by   the  better  vacuum.     Applying  these   correc- 
R  hydraulic  air  pump  is  practically  constant  within  the     tions  in  each  case,  determine  the  saving  in  pounds  of 


head  limits  for  which  it  is  designed'..  The  power  re- 
quired for  reciprocating  air  pumps  can  be  varied  some- 
what by  varying  the  speed,  but  at  a  sacrifice  in  capacity. 
Steam  jet  air  ejectors  require  a  fixed  amount  of  steam 
for  each  stage  or  group  of  nozzles,  but  the  amount  of 

steam  required  to  operate  them  as  a  whole  can  be  varied     the  amounts  that  could  justifiably  be  invested  t 
bv  cutting  out  some  of  the  ejectors,  if  there  are  several     such  savings, 
in  the  unit.     This  is  done  at  a  sacrifice  in  vacuum. 

In  studying   the  auxiliaries   of  the  plant   to  deter- 


sleam  per  hour,  and  then  per  year,  that  each  condenser 
will  effect  over  the  smallest  size.  Knowing  the  cost  of 
producing  steam,  per  thousand  pounds,  the  saving  in 
dollars  per  year  is  then  determined.  Capitalizing  the 
savings  at  a  fair  percentage  for  fixed  charges,  will  give 

ffect 


1 

1 

'^„ 

2.0 

y 



U" 

i^s 

,^ 

y 

F 

/ 

/ 

/ 

/ 

— r 

Rauo  GaBons  per 

H^nuW 

10  Squa/e  Fo 

_1 

FIG     2 — DETERMINING    MOST   ECOXOMIC.M.   K.\T10   OF   W.\TER 
CIRCUL.\TED   TO  ARE.\   OF   .\    SURF.\CE  CONDENSER 


mine  what  type  of  drive  to  use,  the  heat  balance  must 
be  taken  into  consideration.  The  drives  for  the  vari- 
ous power  plant  auxiliaries  should  be  selected  on  the 
basis  of  using  all  the  exhaust  steam  for  heating  the 
boiler  feed.  It  is  practically  impossible  to  design  a 
plant  to  have  the  maximum  boiler  feed  temperature  at 
all  times.  The  usual  scheme  is  to  have  high  feed  water 
temperatures  at  light  loads  and  somewhat  lower  tem- 
peratures at  the  heavier  loads,  in  order  not  to  waste  ex- 
haust steam  at  light  loads.  When  the  necessary  amount 
of  exhaust  steam  has  been  provided,  the  remainder  of 
the  auxiliaries  should  be  motor  driven. 

Cost  data,  together  with  maintenance  costs  and 
performance,  must  also  be  obtained  on  a  number  of 
condensers  before  the  analysis  is  com- 
plete. The  costs  need  be  only  relative  as 
a  comparison  between  the  sizes  is  all  that 
is  necessary  to  determine  the  best  one. 

With  all  this  data  available,  the 
general  method  of  procedure  is  as  follows: 
List  ill  the  condensers  in  tabulated  form 
as  regards  size,  beginning  with  one  that 
is  known  to  be  too  small  for  the  applica- 
tion, and  ending  with  one  that  is  too  large, 
using  standard  sizes  in  between.  The 
proper  condenser  will  be  found  some- 
where among  the  condensers  listed.  With  ' 
each  condenser  determine  "the  vacuum  that  would 
be  obtained  when  condensing  the  average  quantity 
of  steam  with  the  cooling  water  of  average  tem- 
perature. Find  for  each  size  the  improvement 
in  vacuum  in  niches  of  mercury  over  the 
smallest  one.  The  product  of  these  last  figures  by  the 
percentage  correction  per  inch  allowable  on  the  turbine 
vv'ill  give  the  percentage  ihe   steam  passed  will  be  re- 


So  much  for  the  sa\ing  in  steam  on  the  main  unit ; 
next  the  condenser  drive  should  be  considered,  for  it  is 
only  by  greater  expenditure  of  power  on  the  auxiliaries 
that  such  savings  in  steam  as  represented  by  the  use  of 
the  larger  condensers  can  be  obtained.  For  each  con- 
den.ser  find  the  amount  of  auxiliary  power  that  will  be 
required  and  the  excess  over  the  smallest  size.  Then 
fi:id  the  cost,  to  deliver  this  excess  power  to  the  con- 
denser. If  the  auxiliaries  are  steam  driven,  all  the 
steam  being  used  for  heating  the  feed  water,  the  only 
charge  that  can  be  made  is  for  the  heat  lost  in  the  steam 
in  passing  through  the  driving  turbines.  This  is  about 
too  B.t.u.  per  pound,  and  the  equivalent  in  live  steam 
and  cost  of  generating  it  can  readily  be  found.  If  the 
auxiliaries  are  motor  driven,  the  cost  of  power  can  be 
estimated  from  the  cost  of  the  steam  required  by  the 
unit  from  which  the  motors  receive  their  power,  taking 
into  consideration  motor  and  generator  efficiencies,  and 
transmission  losses.  The  costs  of  the  excess  power 
ihus  found  and  capitalized,  at  the  same  percentage  as 
used  for  the  cost  of  the  steam  saved,  give  in  each  case 
an  amount  which  such  an  increased  cost  would  repre- 
sent in  investment. 

The  maintenance  can  be  treated  in  the  same  way 
as  the  cost  of  power,  getting  the  excess  over  the  small- 
est size  and  capitalizing  it  at  the  same  percentage. 
Finallv  the  cost  of  each  condenser  installed  in  the 
plant,  adding  any  extra  installation  costs  due  to  using  a 


TABLE  II— KSTIMATES  TO  DETERMINE  SURFACE  CONDENSER  WITH  MO.ST 
ECONOMICAL  SURFACE  TO  WATER  RATIO 


155 


1  Cuixlenser  size  sq.  ft |15  000 

2  liullons  per  minute  circulated 13  000 

3  H|>,  for  drive ' 

4  H];.  <x<css  over    15  000 

5  Eqiiiv.  sleam  at   12.2  lbs.  per  hp. 

6  Equiv.  sleam  per  yr 

7  Cost  "t  steam  at  35c 

8  Cost  of  sleam  cap.  at  15  per  cent 


14  000 

13  500 

160 


427  000 
$150 
1000 


13  000 

13  900 

169 

14 

171 

1  197  000 

$420 

2800 


12  000 

14  400 

190 

35 

427 

2  989  000 

$1045 

6970 


11000 

15  000 

214 

59 

720 

5  040  000 

$1765 

11  770 


jndenser •164  OOOl  61  0001 

er   15  000   size "        """" 


9  Cost  of 
.0   Saving  t 


11  Maintenance  per  yr • 

12  Saving  over   15  000   size 

13  Savinr  in  Main  cap.  at  15  per  cent. 


54001 

ol 

01 


51001 

300 

2000 


4800 

600 

40001 


45501 
850 
5670] 


4350 
1050 
7000 


$4000         $7000         $73001        $6630 


lari;er  condenser,  are  set  down  and  the  excess  found  as 
before. 

1  laving  determined  the  foregoing,  the  only  thing 
lh;it  remains  to  be  done  is  to  balance  the  savings  against 
the  increased  costs  to  see  which  condenser  is  the  most 
economical.  Taking  the  capitalized  savings  and  sub- 
tracting the  capitalized  excess  operating  and  mainten- 
ance costs,  also  the  trxcess  installation  costs,  select  the 


January,   1921 


THE  ELECTRIC  JOURNAL 


19 


condenser  that  shows  the  greatest  difference,  for  it  is 
this  condenser  that  makes  the  greatest  saving,  all  things 
considered.  If  the  figures  are  plotted  in  the  form  of  a 
curve  using  condenser  sizes  on  the  horizontal  scale  and 
capitalized  savings  minus  increased  costs  on  the  verti- 
cal, the  point  where  the  curve  reaches  a  maximum  is 
the  point  of  selection. 

To  illustrate  the  various  steps  mentioned,  a-  con- 
crete example  is  given.     In  this  case  for  the  purpose  of 


1 

i 

^ 

\ 

3 

^ 

[^ 

\, 

s     " 

s 

\ 

& 

1 

\ 

\ 

1       , 

\ 

Q       ' 
1 

i 

U 

)00 

"i 

000 
ondens 

^^  Size 

00 
„S.u 

ire  Fe 

16 

boo 

FIG.   3 — DETERMINING    MOST   ECONOMICAL   SIZE  OF   SURFACE 
CONDENSER 


illustration  all  the  data  has  been  assumed  and  any  of 
the  figures  given  should  be  considered  accordingly. 
Assume  a  10  000  kilowatt  plant  with  the  following  con- 
ditions: Operation  7000  hours  per  year  average,  at 
80  percent  load  factor;  steam  is  generated  at  200  lbs. 
gage  pressure,  100  degrees  superheat;  sufficient  ex- 
haust steam  is  available  for  heating  without  using  tur- 
bine driven  auxiliaries ;  the  aver- 
age cooling  water  temperature  is 
75  degrees;  the  external  discharge 
head  on  the  circulating  pump  is  10 
ft.,  total  head  on  the  condensate 
pump  is  80  ft. ;  cost  of  steam  is  35 
-cents  per  thousand  pounds.  With 
this  data  in  mind,  a  jet  condenser 
j'.nd  then  a  surface  condenser  will 
be  selected. 


I'or  this  reason  an  industrial  plant  with  a  low  load  fac- 
tor should  not  choose  as  large  a  condenser  for  a  given 
turbine  as  would  the  central  station  plant  with  high 
load  factor. 

Using  the  same  set  of  conditions  for  the  surface 
condenser  selection,  a  slightly  different  problem  arises, 
since  another  variable  is  introduced.  The  size  of  the 
condenser  may  be  varied  and  the  ratio  of  the  gallons 
circulated  to  the  surface  in  square  feet  may  also  be 
changed.  It  is,  therefore,  first  necessary  to  establish 
the  proper  ratio  of  water  to  surface,  and  then  proceed 
with  the  selection  of  the  size  of  condenser  with  this 
ratio  fixed. 

To  find  the  best  ratio,  first  choose  a  vacuum,  based 
on  common  practice,  where  it  is  expected  that  the  con- 
denser will  operate  most  of  the  time,  in  this  case  say  28 
inches  with  the  75  degrees  feed  water,  when  condensing 
100  000  lbs.  of  steam  per  hour.  Next  find  a  number  of 
condensers,  with  varying  ratios  of  water  to  surface, 
that  will  give  this  vacuum.  Then  ascertain  the  cost  of 
supplying  power  to  the  pumps,  and  the  excess  over  the 
cheapest  one  to  operate.  Set  down  the  first  costs  and 
the  saving  in  cost  over  the  most  expensive  one,  which 
will  also  be  the  cheapest  to  operate.  Determine  the 
maintenance  charges  and  the  saving  in  maintenance 
over  the  largest  size.  Finally  balance  the  capitalized 
savings  against  the  capitalized  costs,  and  the  condenser 
showing  the  greatest  difference  has  the  best  economical 
ratio.  For  the  given  case  the  calculations  are  tabulated 
in  Table  II,  which  shows  that  the  12000  square  foot 
condenser,  circulating  14  40Q  gallons  per  minute,  or  the 


TABLE   III — ESTIMATES   TO   DETERMINE    SURFACE   CONDENSER 
PRODUCING   MOST   ECONOMICAL   VACUUM 


1  Condenser   Size   sq.    ft 

2  Gallons  per  minute  circulated 

3  Vacuum,    75°    Water,    100  000   lbs.   steam. 

4  Improvement  in  Vac.  over  12  000  size... 

5  Per  cent  correction  at  5  per  cent  per  inch 

6  Saving  in  steam  per  hour 

7  Saving  in   steam  per  year 

8  Cost  of  steam  at  35  cents    

9  Cost  of  steam  capitalized  at  15  per  cent. 


10  Hp,  for  drive 

11  Excess  over  12  000  size 

12  Equiv.  steam  at  12.2  Ihs.  per  hp 

13  Equiv.   steam  per  year 

14  Cost  of  steam  at  35  cents 

15  Cost  of  steam  capitalized  at  15  per  cent 


16  Maint 

17  Exces 

18  Exces 


For  the  jet  condenser,  the  re- 
sults of  the  calculations  and  esti- 
mates are  shown  in  Table  I.  All 
results  throughout  are  slide  rule 
calculations.  Plotting  the  results 
shown  in  line  21  of  Table  I, 
the  curve  in  Fig.  i  is  obtained.  It  will  be  noticed 
that  the  curve  reaches  its  maximum  point  at 
the  10  000  gallons  per  minute  condenser,  and  it  is  quite 
evident  that  this  is  the  best  condenser  for  the  assumed 
conditions,  since  it  is  with  this  machine  that  the  great- 
est saving  is  made.  Analyzing  the  results  it  will  be 
seen  that  the  higher  the  load  factor  the  larger  the  con- 
denser that  could  be  justified,  since  it  is  the  saving  in 
the  steam  on  the  main  unit,  by  the  use  of  higher 
vacuum,  that  plays  an  important  part  in  the  selection. 


c«  per  year 

jin.   over    12  000    size 

lin.  capitalized  at  15  per  cent.  . 


Costs  9 — 15 — 18 — 20. 


12  000 

13  000 

14  000 

15  000 

14  400 

15  600 

16  800 

18  000 

27.98 

28.1 

28.21 

28.28 

0 

0.12 

0.23 

0.30 

0 

0.6 

1.15 

1.5 

0 

600 

1150 

1500 

n 

4  200  000 

8  050  000 

10  500  000 

0 

$1470 

$2820 

$3680 

0 

9700 

18  800 

24  500 

203 

216 

228 

13 

26 

38 

159 

317 

463 

1  113  000 

2  219  000 

3  241  000 

$390 

$776 

$1153 

2600 

51801 

7700 

16  000 
19  200 
28.34 


634 

4  438  000 

$1680 

10  520 


42301 

330 

2200 


45501     48501 

6501      950 

4340      6330 


5200 
1300 
8670 


one  having  a  ratio  of  1.2  to  I,  is  the  most  economical. 
The  results  as  indicated  in  the  last  line  of  Table  II  are 
represented  in  curve  form  in  Fig.  2,  and  reach  the 
maximum  point  at  the  12  000  square  foot  size. 

Having  selected  the  proper  ratio,  the  next  step  is 
to  select  the  condenser  with  this  ratio  that  will  produce 
the  most  economical  vacuum.  In  arriving  at  this  re- 
sult it  will  be  noted  that  there  will  be  a  slight  chance  for 
error,  if  the  vacuum  on  which  the  ratio  is  chosen  does 
not  approximate  that  obtained  later,  but  the  difference 


THE   ELECTRIC  JOURNAL 


\nl.  XVIII,  No.   I 


is  so  small  that  it  can  be  disregarded  for  all  practical 
purposes.  The  general  method  of  procedure  is  the 
same,  selecting  various  sizes  and  comparing  them  on  a 
cost  and  savings  basis.  Thus  Table  III  should  be  quite 
clear. 

From  Table  III  it  is  evident  that  the  14  000  square 
foot  condenser,  circulating  16  800  gallons  per  minute  is 
the  best  condenser  for  this  application.  The  results  as 
indicated  in  the  last  line  of  Table  III  are  represented  in 
curve  forms  in  Fig.  3.     In  the  problem  of  the  selection 


of  the  size  it  is  quite  apparent  that  the  feed  water  treat- 
ing question  has  not  been  considered.  With  a  given 
type  of  condenser  practically  the  same  amount  of  treat- 
ing will  be  necessary,  and  since  it  is  only  the  differential 
that  is  pertinent,  the  feed  problem  may  be  disregarded. 
The  general  plan  followed  in  the  foregoing  is  also 
applicable  to  the  selection  of  almost  any  kind  of  ap- 
paratus, for  it  is  only  by  comparing  the  different  sizes 
and  designs,  and  forecasting  what  each  will  do  in  ser- 
vice, that  we  are  able  to  make  the  proper  selection. 


A.  NYMAN 

The  definition  of  "power  factor  in  polyphase  circuits"'   is    receiving  a   good   deal   of   discussion   at   the 
present  time.     The  aim  of  this  article  is  to  present  briefly   some  of   the   main   considerations   entering   into 

this  discussion. 


THE  term  "power  factor"  as  applied  to  single- 
phase  circuits,  owes  its  origin  to  an  economic 
necessity.  The  capacity  of  the  electric  ma- 
chinery and  of  the  distribution  network  and  the  expense 
of  supplying  electric  power  are  directly  dependent  on 
this  factor.  With  the  rise  of  polyphase  systems,  the 
same  factor  was  applied  to  individual  phases.  As  long 
as  the  loads  were  balanced,  this  factor  was  common  to 
all  phases  and  could  be  used  to  represent  the  load  con- 
ditions accurately.  As  the  number  and  magnitude  of 
single- phase  loads  drawing  power  from  polyphase  cir- 
cuit increased,  it  became  more  apparent  that  the  old 
"power-factor"  was  insufficient.  A  new  basis  must  be 
found  for  determining  to  what  extent  individual  con- 
sumers should  be  held  responsible  for  the  loading  con- 
ditions existing  on  the  line. 

A  number  of  possible  definitions  have  been  in  use. 
As  long  as  most  single-phase  loads  are  approximately 
balanced  one  against  the  other,  there  is  little  difference 
m  results  given  by  various  definitions.  Lately,  how- 
ever, large  power  loads  with  considerable  unbalance 
have  come  into  use  and  made  it  desirable  to  standard- 
ize on  a  definition  which  would  be  satisfactory  from 
technical  and  commercial  viewpoint.  The  A.  I.  E.  E. 
and  the  N.  E.  L.  A.  have  formed  a  joint  committee  to 
carry  out  this  standardization.  This  committee  has 
brought  forward  a  wide  discussion  of  this  subject. 

In  general,  three  classes  of  people  are  interested  in 
i;  suitable  definition  of  "power- factor"  : — 

The  producer  of  electric  energy. 

The  consumer  of  electric  energy. 

The  manufacturer  of  electric  machinery. 

In  considering  the  conditions  affecting  central  sta- 
tion operation,  the  presence  of  unbalanced  load  has  a 
direct  result  in  the  rising  losses  in  the  generating  units 
and  distributing  network.  Comparing  unbalanced  load 
with  a  balanced  load  of  the  same  kilowatts,  the  power 
station  must  bear  the  cost  of  additional  coal  burned  and 
the  interest  and  depreciation  on  the  additional  plant  ca- 
pacity.    This  additional  cost  could  form  a  basis  for  de- 


linuig  power- factor.  The  disturbance  of  voltage,  as 
created  by  unbalanced  load,  is  a  far  more  serious  fea- 
ture; its  result  is  poor  service  from  the  station.  The 
unbalance  in  voltage,  if  large,  cannot  be  easily  cor- 
rected. Synchronous  motors  or  phase  balancers  can 
minimize  this  effect,  but  must  be  located  close  to  the 
source  of  disturbance  in  order  to  be  effective.  Lagging 
current  in  the  line  has  approximately  the  same  effect  on 
regulation  as  unbalance.  It  can  be  corrected  by  suit- 
able appliances,  but  in  order  to  be  most  effective,  the 
latter  must  be  located  close  to  the  source  of  lagging  cur- 
rent. The  two  causes  of  poor  regulation  may  be  cor- 
rected by  separate  means.  The  cost  of  correction  can 
he  estimated  separately. 

The  above  considerations  suggest  the  use  of  two 
factors —  ( 1 )  To  represent  phase  lag  in  the  system,  as- 
suming all  the  load  balanced — (2)  To  represent  un- 
balance. Such  a  method  of  measurement  could  have 
an  exact  scientific  basis  and  could  be  made  to  represent 
each  load  condition  accurately.  Several  practical  ob- 
jections are  raised  against  this  method.  The  use  of  an 
additional  term  like  "unbalance  factor"  would  involve  a 
further  complication  in  determining  the  rate  to  be  paid. 
Producers  and  consumers  must  all  be  conversant  with 
the  technical  meaning  of  this  new  term  in  order  to  ap 
predate  its  importance  and  avoid  disputes. 

From  the  customer's  standpoint  both  the  quality  of 
the  service  and  the  fairness  and  simplicity  of  the  rates 
are  factors  of  importance.  The  users  of  large  single- 
phase  loads  must  be  assured  that  whatever  penalty  is 
placed  on  their  type  of  load  is  commensurate  with  the 
rctual  cost  of  supplying  this  load  and  of  maintenance  of 
service  to  other  customers.  Certain  consumers,  such  as 
large  electric  furnaces  or  single-phase  railways,  could 
be  induced  to  install  phase  balancers.  This  would  pro- 
tect the  rest  of  the  system  and  bring  the  burden  of  un- 
balanced load  directly  to  the  customer. 

Polyphase  machinery  on  circuits  with  unbalanced 
voltages  draws   unbalanced    currents.     These   currents. 


January,   1921 


THE  ELECTRIC  JOURNAL 


while  beneficial  to  the  rest  of  the  system,  are  a  source 
of  losses  and  reduction  of  capacity  to  the  machinery 
through  which  they  flow.  Any  scheme  that  would 
apply  a  single  factor  for  both  phase  lag  and  unbalance 
would  treat  such  load  unfairly.  With  two  sepearate 
factors,  the  unbalance  existing  in  the  polyphase  ma- 
chinery will  not  necessarily  affect  the  charge.  The  un- 
balance   factor    can    be    simply    overlooked.     On    the 


I'o-i'cr-factor  z= 


total  watts 


(/) 


I-IC.      1 — DERIVATIUN     OF     POWER-FACTOR 

For  a  particular  case  of  unbalanced  currents. 

whole,  a  scheme  for  measuring  phase  lag  and  unbalance 
separately  would  be  desirable,  provided  the  calculations 
•of  rates  were  simple. 

From  the  manufacturer's  point  of  view,  the  discus- 
sions of  unbalance  factor  brings  up  a  number  of  points 
concerning  the  protection  of  polyphase  machinery  on 
tinbalanced  voltage  systems.  All  such  machineiy  is 
subject  to  additional  losses  when  such  voltage  exists. 
These  losses  are  partly  distributed  throughout  the  ma- 
■chine  and  partly  concentrated  in  certain  portions  of  the 
machines.  Consider  the  case  of  an  induction  motor 
with  the  voltage  in  one  phase  higher  than  the  others. 
This  phase  will  draw  a  comparatively  high  current  and 
the  winding  of  this  phase  will  be  overheated.  At  the 
same  time,  an  induced  voltage  is  added  to  the  rotor, 
which  creates  further  losses  distributed  throughout  the 
Totor. 

For  close  technical  analysis  of  working  conditions, 
separate  measurements  of  power-factor  and  unbalance 
appear  desirable.  In  this  way  the  capacity  of  the  ma- 
chinery can  be  determined  with  due  regard  given  to 
working  conditions  of  phase  shift  and  unbalance.  Both 
factors  must  be  also  included  in  wording  the  contracts 
for  machinery.  This  will,  unfortunately,  introduce 
some  new  clauses  in  an  already  highly  tecl^nical  legal 
<iocument. 

.'\.s  far  as  metering  is  concerned,  it  is  possible  to 
design  meters  to  measure  a  power-factor  of  almost  any 
kind  of  definition.  However,  separating  the  measure- 
ment of  power-factor  and  unbalance  permits  the  use  of 
very  simple  schemes  for  measuring  both,  meters  of 
standard  types  of  construction  could  be  used. 

POSSIBLE  DEFINITIONS 

Single  Factors — Several  definitions  have  been  sug- 
gested-to  represent  the  power-factor  in  a  polyphase  sys- 
tem and  take  account  of  unbalance.  A  single  factor  is 
then  used  for  complete  determination  of  the  load  condi- 
tions, as  opposed  to  a  double  factor,  one  for  measuring 
phase  shift  and  the  other  for  measuring  unbalance.  The 
following  single  factors  may  be  mentioned. 


arithmetic  sum  of  volt  amperes 
where  volt  amperes  are  determined  by  measuring  the 
current  in  each  phase  and  the  voltage  from  each 
phase  to  an  artificial  neutral  formed  by  three  equal  im- 
pedances. This  definition  has  been  tentatively  sug- 
gested by  the  Joint  Committee  of  the  A.  I.  E.  E.  and 
N.  E.  L.  A.  as  one  of  two  alternative  definitions.  It 
takes  account  of  unbalance,  though  not  on  any  scientific 
basis.  Its  main  advantage  is  simplicity  and  ease  of  de- 
rivation. 

total  watts 


I'ozi'cr-factor  : 


(^) 


J  X  r.m.s.  current  X  r.m.s.  volts 

where  r.m.s.  current  is  derived  from  the  three  measured 

values  of  current  by  taking  the  root  mean  square  of  the 

three  values.     R.m.s.  volts  are  derived  in  the  same  way 

from  the  voltages,  measured  as  in  definition  i. 

This  definition  gives  a  value  of  power-factor  which 

bears  a  definite  relation  to  the  losses  in  polyphase  supply 

circuit:  namely,  the  losses  are  the  same  as  would  exist 

.  ,        ,     ,  ,    .        ,  1      J  measured  watts 

with  a  balanced,  ni-phase  loan  =  2 — r~ 

'        '  fozver  factor 

This  is  the  same  relation  as  exists  for  a  single  phase 

power-factor. 

The  chief  disadvantage  of  this  factor  is  its  compli- 
cated derivation.  Direct  measurement  of  this  power- 
factor  would  be  very  difficult  if  not  impossible.  How- 
ever, meters  to  measure  r.m.s.  of  three  currents  or 
r.m.s.  of  three  voltages  could  be  constructed. 

Double  Factors — The  power-factor  for  this  method 
of  considering  the  problem  disregards  the  effect  of  un- 
balance. A  separate  unbalance  factor  is  advocated  to 
measure  the  latter.  Different  ways  of  defining  "power- 
factor"  on  this  basis  have  been  suggested.  The  results 
given  are,  however,  nearly  identical. 

total  watts^ .         .  , 

Power-factor  =  ^^,or  sum  of  volt-amperes    ^^' 

This  definition  is  variously  referred  to  as  vector 
power  factor  or  Italian  power- factor.  It  is  the  second 
alternative  definition  suggested  by  the  joint  committees. 
The  vector  sum  of  volt-amperes  can  be  obtained  by  geo- 
metric construction,  using  volt  amperes  as  vectors  with 
the  respective  angles  corresponding  to  angles  of  lead  or 
lag  in  each  individual  phase.     Fig.  i  shows  the  deriva- 


FIG.   2— THREE-PHASE   SYSTEM    WITH    NEUTRAL  OPEN   CIRCUITED 

Resolved  vectorially  into  two  balanced  three-phase  systems, 
tion  of  this  power-factor  for  a  particular  case  of  unbal- 
anced currents.  It  will  be  noticed  that  for  a  balanced 
voltage  condition  the  current  unbalance  is  completely 
disregarded.  If,  however,  a  voltage  unbalance  exists, 
the  power-factor  measurement  is  affected. 

In  order  to  understand  the  difference  between  this 
definition  and  the  following,  a  brief  outline  of  Mr.  C.  L. 
Fortescue's  method  of  analysis  will  be  given. 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


It  can  be  shown  that  any  three-phase  system  with 
neutral  open  circuited  can  be  decomposed  vectorially 
into  two  balanced  three-phase  systems,  Fig.  2, — the  one 
with  the  sequence  of  phases  in  one  direction,  the  other 
with  the  sequence  in  the  opposite  direction.  Thus  the 
system  A,  B,  C  is  decomposed  into  the  system  A^B^C^, 
which  may  be  called  positive  sequence,  and  A^B^C^ 
which  may  be  called  the  negative  sequence.  It  can  also 
be  shown  that  this  decomposition  is  perfectly  definite 
for  each  particular  case, — that  is,  only  one  combination 
of  magnitudes  and  phases  of  this  nature  can  satisfy 
each  condition.  It  can  be  shown  furthermore  that  the 
positive  sequence  is  the  only  useful  part  in  polyphase 
machinery.  In  fact,  the  negative  sequence  of  currents 
is  equivalent  to  a  current  flowing  in  a  direction  opposite 
to  that  of  synchronous  rotation  of  the  machine.  The 
result  is  a  reduction  in  working  torque  of  motors  and 
additional  losses  in  all  polyphase  machinery.  In  every 
circuit  carrying  currents  of  positive  and  negative  se- 
quence, the  total  losses  equal  the  sum  of  losses  due  to 
the  positive  and  the  negative  sequences.  The  total 
power  and  total  reactive  power  are  similarly  equal  to 
the  algebraic  sum  of  the  respective  values  in  the  posi- 
tive and  in  the  negative  sequence;;.  In  a  balanced  sys- 
tem, it  will  be  found  that  the  negative  sequence  disap- 
pears. 

The  above  analysis  of  a  three-phase  system  into  a 
positive  and  a  negative  sequence  resembles  in  many  fea- 
tures the  analysis  of  a  single-phase  condition  into  in- 
phase  and  out-of-phase  components,  or  into  real  and  re- 
active powers.  It  is  evident  that  the  negative  sequence 
could  be  considered  as  the  most  correct  and  definite 
measurement  of  unbalance,  which  can  be  treated  as  in- 
dependent of  the  balanced  or  positive  sequence,  but 
obeying  the  same  laws.  The  total  resulting  condition 
is  then  the  sum  of  the  effect  of  positive  and  negative  se- 
quence. 

i'atts  positive  sequence 


Pozver-factor  = 


Unhalance-factor 


volt  amperes  positive  sequence 

current  negative  sequence 


(■/) 


other  which  would  include  the  voltage  unbalance  to  de- 
fine the  unbalance  factor.  In  practice  the  voltage  un- 
balance is  small  and  it  is  really  the  current  unbalance 
that  is  the  origin  of  harmful  effects. 

As  mentioned  above,  a  distinction  must  be  made 
between  the  unbalance  created  by  a  single-phase  load, 
and  that  drawn  from  a  polyphase  machine  by  virtue  of 
unbalanced  voltage.  Such  discrimination  could  be 
achieved  automatically  by  measuring  the  phase  of  nega- 
tive sequence  current  with  relation  to  negative  sequence 
voltage. 

real  power  positive  sequence 
fowei  -factor         ^^^^  power  pos.  seq.  -j-  reactive  power  pas.  seq. 

(5) 

This  definition  is  equivalent  to  definition  (4)  except 
stated  in  a  different  way.  Definition  (3)  differs  from 
it  by  the  fact  that  it  takes  into  account  the  real  power 
of  negative  sequence  and  reactive  power  of  negative  se- 
quence. The  advantage  of  definition  (4)  or  (5)  over 
definition  (3)  is  in  the  fact  that  it  disregards  the  volt- 

T.\BLE  I — POWER-FACTOR  OBTAINED  BY  DEFINITIONS  (I). 
(2),  (3)  AND  (4)  UNDER  CERTAIN  LOAD  CONDITIONS 


current  positive  sequence 
This  definition  of  power-factor  is  different  from 
definition  j  only  in  case  of  voltage  unbalance.  This  is 
apparent  by  considering  the  volt  amperes  due  to  the 
negative  sequence  current  and  positive  sequence  volt- 
age :  the  vectorial  sum  of  these  volt  amperes  is  equal  to 
zero.  Hence  only  the  vector  sum  of  volt  amperes  of 
positive  sequence  current  and  positive  sequence  voltage 
determine  the  power-factor  (3)  and  give  a  value  equal 
to  that  of  definition  (4).  However,  if  a  negative  se- 
quence voltage  is  present,  the  negative  sequence  voltage 
and  the  negative  sequence  current  give  a  value  of  volt 
amperes  which  add  vectorially  to  the  volt-amperes  of 
positive  sequence.  Thus  the  value  of  power-factor  by 
definition  (3)  will  differ  from  that  by  definition  (4). 
The  latter  definition  disregards  completely  the  effect  of 
unbalanced  voltage. 

The  unbalance  factor  gives  a  direct  measure  of  un- 
balanced  current.     This   definition   is   preferred  to  any 


age  unbalance  completely.  The  unbalance  condition 
can  then  be  measured  independently  by  unbalance 
factor. 

It  is  possible  to  construct  circuits  which  will  mea- 
sure power- factor  and  unbalance  factor  accurately  ac- 
cording to  definition  (4)  and  use  meters  of  almost 
standard  construction.  This  would  be,  of  course,  of 
immense  advantage  on  existing  power  networks,  and 
with  the  manufacturers  of  measuring  instruments. 
Easy  conversion  to  meters  suitable  to  this  new  detmi- 
tion  is  made  possible.  The  practical  difficulty  in  ac- 
cepting this  definition  is  that  a  new  method  of  analysis 
of  circuits  must  be  introduced  and  accepted  by  a 
majority  of  interested  parties. 

In  the  matter  of  rate  making,  the  following  proce- 
dure has  been  suggested.  The  present  method  of  charg- 
ing for  low  power- factor  should  be  complemented  by 
introducing  a  similar  charge  for  unbalance  factor.  It 
will  be,  of  course,  necessary  to  get  the  approval  of 
technical  authorities  of  government  institutions  before 
any  such  method  could  be  universally  accepted. 

Table  I  illustrates  by  concrete  examples  the  results 
given  by  various  definitions  under  certain  load  condi- 
tions. 


Ttiroe-Phaso 


CurroiiX 


/jrujxLiig 


llo  actors 


M.  E.  SKINNER 

Transformer  Engineering  Dcpt., 
Westinghouse  Electric  &  Mfg.  Company 


THE  COMMON  form  of  current  limiting  reactor 
consists  of  a  cylindrical  coil  of  stranded  copper 
cable  supported  in  a  fireproof  structure.  The 
usual  practice  has  been  to  provide  three  single-phase 
reactors  for  each  three-phase  circuit  to  be  protected. 
This  arrangement  lends  itself  toward  carrying  out  the 
segregation  of  the  different  phases  which  is  being  ad- 
vocated in  modern  bus  structures.  However,  con- 
siderable space  is  necessary  for  the  accommodation  of 
three  coils  and,  where  the  station  was  not  originally  laid 
out  to  provide  for  reactors,  it  is  often  impossible  to  find 
room  for  them. 

The  three-phase  type  of  reactor  will  often  offer  an 
easy  solution  when  other  conditions  are  within  the  limi- 
tations of  this  type  of  coil.  By  a  three-phase  reactor  is 
meant  one  in  which  the  coils  for  all  three  phases  are 
contained  in  a  common  structure  and  are  so  disposed  as 
to  take  advantage  of  the  mutual  inductance  between  the 
various  phases. 

FUNDAMENTAL    RELATIONS 

Any  conductor  carrying  current  is  surrounded  by  a 
magnetic  field  whose  intensity  diminishes  as  the  dis- 
tance from  the  conductor  increases,  li  the  magnetic 
field  at  any  point  is  unidirectional  and  of  constant  value, 
no  voltage  will  be  induced  in  nearby  conductors,  unless 
they  are  moved  about  in  this  field.  However,  if  the 
magnetic  field  is  alternating,  any  conductor  within  its 
sphere  of  influence  will  have  a  voltage  induced  in  it. 

Energy  is  required  to  establish  any  magnetic  field. 
In  the  case  of  direct  current,  the  energy  is  expended  in 
building  up  the  magnetic  field  and  is  stored  in  the  field 
until  the  circuit  is  broken,  at  which  time  it  is  returned 
in  the  form  of  the  well-known  "inductive  kick."  When 
the  current  alternates,  the  energy  is  stored  in  the  mag- 
netic field  while  the  current  is  increasing  and  is  re- 
turned to  the  circuit  when  the  current  decreases.  The 
inductance  of  an}-  circuit  is  a  measure  of  the  energy 
stored  in  that  circuit.  To  make  clear  the  distinction 
between  self  and  mutual  inductance,  refer  to  Fig.  i. 
Here  is  represented  a  cross  section  of  a  conductor  a 
carrying  a  certain  current.  The  concentric  circles  re- 
present the  lines  of  force  of  the  magnetic  field  produced 
by  the  current  in  a,  the  spacing  of  the  lines  representing 
roughly  the  field  mtensity.  Certain  lines  concen- 
tric about  a  enclose  conductor  h:  whereas,  others  are 
completed  without  encircling  it.  The  self-inductance 
is  a  measure  of  the  total  field  set  up  around  a,  neglect- 
ing the  presence  of  b,  and  the  self-inductive  voltage  is 
the  voltage  necessary  to  maintain  the  field.  The  mutual 
inductance  of  a  on  b  is  a  measure  of  that  portion  of  the 


field  which  is  beyond  b,  and  the  mutual  inductive  volt- 
age is  the  voltage  induced  in  &  by  a  current  in  a.  Ob- 
viously, the  closer  the  spacing  between  the  conductors, 
the  greater  will  be  the  mutual  inductance  between  them. 

Independent  of  a,  conductor  b  may  be  carrying  a 
current  which  will  set  up  a  field  of  its  own,  similar  to 
that  shown  for  o.  The  phase  relationship  between  the 
self  inductive  voltage  in  b  and  the  mutual  inductive 
voltage  due  to  the  current  in  a  will  be  the  same  as  the 
respective  currents  in  the  two  conductors. 

Single  conductors  have  been  cited  for  the  sake  of 
clarity,  but  similar  relations  hold  for  groups  of  conduc- 
tors or  coils.  Whether  the  mutual  inductive  voltages 
add  to  or  subtract  from  the  self  inductive  voltages  will 
depend  upon  the  relative  polarity  or  direction  of  wind- 
ing of  the  coils. 

The  simplest  form  of  three-phase  coil  would  ob- 
viously consist  of  three  identical  coils  mounted  one 
above  the  other  and  connected  as  shown  in  Fig.  2.  The 
vector  position  of  the  self  inductive  voltages  produced 
by  three-phase  currents  flowing  from  A^,  B^  and  C,  to- 


F   FORIF.   OF    A    M.\i;NF.TIC    FIELD 


ward  A^,  B„,  C,  would  be  as  shown  by  the  vectors  OA, 
OB  and  OC  in  Fig.  5.  If  the  mutual  inductive  voltage 
between  adjacent  coils  is  taken  as  20  percent  of  the  self 
inductive  voltage,  (the  mutual  inductance  between  the 
extreme  coils  being  negligible  on  account  of  the  great 
spacing)  its  value  and  phase  position  is  as  shown  by  the 
vectors  A-Mua,  B-M^b,  etc.,  and  the  resultant  voltage 
will  be  the  vector  sum.  The  symbols  and  subscripts 
may  be  interpreted  as  follows: — A-Mba  represents  the 
mutual  inductive  voltage  produced  in  phase  ^  by  a  cur- 
rent flowing  in  phase  B ;  B-Mab  represents  the  mutual 
inductive  voltage  produced  in  phase  B  by  a  current 
flowing  in  phase  A. 

It  will  be  noticed  in  this  case  that  the  resultant 
voltage  is  less  than  the  self  inductive  voltage.  The  re- 
sultants are  not  all  of  equal  magnitude,  and  their  phase 
position  has  been  shifted  from  the  120  degrees  relation. 
A  comparison  of  Figs.  2  and  3  shows  the  result  of  re- 
versing the  middle  phase.  As  in  Fig.  2,  the  voltages  are 
not  equal  and  the  phase  position  is  shifted.  In  both 
cases  the  magnitude  of  the  three  resultant  voltages  may 
be  made  the  same  by  increasing  or  decreasing  the  num- 


24 


THE  ELECTRIC  JOURNAL 


Vol.  XVIIL  No.  I 


ber  of  turns  in  the  end  coils.     The  phase  shift  however, 
will  still  persist. 

In  Fig.  4  is  shown  a  three-phase  reactor  with  one 
coil  split  into  two  equal  and  opposed  halves,  which  con- 
stitute the  end  coils  of  the  unit.  By  this  rather  novel 
scheme  the  resultant  voltages  in  the  three  phases  can 
not  only  be  made  to  have  equal  magnitudes  but  their 


— 

^  r 

— 

1     ' 

n 

1  i_ 

t 





__^ 

1 

i 

c^n. 

" 

; 



"-- 

— 

H 

_J     1=^ 

' — 

J    ^ 

_J 

Fig.  2 


A,         B,       C, 

Kg.  3 


Mac       ii 


.  \L^' 


Rg.   5 


Fig.  6 


FIG.    2 — THREE    SIMIL.\R    COILS    .MOU.N'TED    O.NE    ABOVE    THE   OTHER 

FIG.     3 — THREE     SIMIL.^KR     COILS     H.WING     MIDDLE     PHASE    REVERSED 

FIG.     4 — ONE    COIL    SPLIT    INTO    EQUAL    AND    OPPOSITE    HALVES 

WHICH    CONSTITUTE   THE    END   COILS 

FIG.    5 — VOLTAGE   VECTORS    FOR   CONNECTIONS    IN    FIG.    2 

FIG.    6— VOLTAGE    VECTORS    FOR    CONNECTIONS    IN    FIG.    3 

FIG.    7 — VOLTAGE   VECTORS    FOR    CONNECTIONS    IN    FIG.    4 

phase  displacement  can  also  be  maintained  at  120  de- 
grees, as  shown  in  Fig.  7.  The  total  voltage  across 
phase  A  is  Mca-^I^ba,'  that  across  phase  B  is  o-b  and 
that  across  phase  C  is  o-c. 

MECHANICAL  FORCES  MAKE  REVERSED  COIL  NECESSARY 

Independent  of  the  addition  of  the  voltage  due  to 
mutual  inductance,  a  consideration  of  the  mechanical 
forces  which  exist  under  short-circuit  conditions  would 
dictate  that  a  60  degrees  relation  between  adjacent  coils 
such  as  is  obtained  by  the  reversal  of  coils  shown  in 
Figs.  3  and  4  is  the  only  practical  one.  The  forces  be- 
tween magnetic  fields  always  act  in  such  a  direction  as 
to  increase  the  total  flux  and  therefore  the  total  induc- 
tive voltage.  The  forces  are  therefore  attraction  be- 
tween adjacent  coils  when  they  are  connected  as  shown 
in  Figs.  3  and  4  and  are  repulsion  when  the  coils  are 
connected  as  shown  in  Fig.  2.  Since  it  is  necessai-y  to 
construct  the  coil  structure  of  insulating  and  at  the 
same  time  fire  proof  material,  which  invariably  has  poor 
tensile  strength,  it  is  imperative  that  the  forces  be  com- 
pressional. 

A  typical  three-phase  reactor  is  shown  in  Fig.  8. 
This  three-phase  type  has  a  very  decided  advantage 
over  three  single-phase  coils  in  point  of  floor  space,  at 
the  expense  of  a  small  increase  in  head  room.  For  ex- 
ample, on  a  6500  kv-a,  1 1  000  volt,  three-phase,  60-cycle 
circuit,  the  space  occupied  by  three  single-phase  coils 
of  3.5  percent  reactance,  including  the  necessary  clear- 


ances, would  be  approximately  3  ft.  4  in.  by  10  ft.  floor 
space  by  4  ft.  8  in.  head  room.  One  equivalent  three- 
phase  reactor  would  require  approximately  4  ft.  5  in. 
by  5  ft.  2  in.  floor  space  by  10  ft.  head  room.  The  ratio 
of  the  floor  space  is  practically  3  to  2.  The  increase 
in  head  room  is  seldom  a  disadvantage,  as  it  is  always 
desirable  to  have  enough  headroom  in  any  compartment 
to  allow  a  man  to  pass  without  stooping,  and  usually 
the  head  room  is  fixed  by  other  considerations  than  the 
height  of  the  reactor.  The  saving  in  floor  space  may 
in  some  cases  allow  the  installation  of  reactors  in  old 
and  crowded  stations,  where  single-phase  coils  would  be 
out  of  the  question.  In  point  of  cost,  the  three-phase 
type  has  only  a  slight  advantage,  as  the  cost  of  insulat- 
ing between  phases  largely  offsets  the  reduction  in  the 
amount  of  copper  required. 

SPHERE  OF  APPLICATION 

Unfortunately,   the   sphere   of   application   of   this 
type  of  coil  is  somewhat  restricted  by  certain  limitations 
inherent   in   its   construction.     It   is  not   feasible  in  re- 
actors to  use  cables  greater  than  about  one-half  inch  in 
diameter    without    running    up    the    stray    losses    very 
rapidly.     There    is    thus   a    rather    sharp    limit    to    the 
amount  of  current  which  can  be  handled  by  a  single 
cable.     In  the  case  of  single-phase  coils,  it  is  possible  to 
wind  several  cables  in  parallel  in  such  a  Way  as  to  make 
them  divide  the  current  equally.     The  method  used  to 
obtain  equal  current  division  among  the  various  cables, 
necessitates  bringing  leads  to   the  center  of  the  coil. 
With  single-phase  coils, 
the     leads     can     be 
brought  out  the  top  and 
bottom    without    cross- 
ing, but  with  a   three- 
phase  reactor  the  cross- 
ing of  the  leads  within 
the      rather     restricted 
space  inside  the  coils  of 
any     but     reactors     in- 
tended   for    low-voltage 
circuits    would    make  it 
impossible  to  meet  the 
rather     .severe     tests 
which  it  is  customary  to 
apply  to   current  limit- 
ing reactors.     The  tests 
applied    to    three-phase 
reactors    by    the   West- 
iiighouse  Co.  are  as  fol-    ^j^    g— a   typical   three-phase 


l.ine  Voltage 


Volts  between  Adjacent 

Coils  at  60  Cycles  for 

One  Minute 


Up  to  2500  20 000 

_'5oo  to  7500  35  000 

7500  to  12  500 50  000 

12500  to  17500  70000 


January,  1921 


THE  ELECTRIC  JOURNAL 


Even  without  multiple  cable  windings  it  has  been 
found  almost  impossible  to  meet  these  tests  with  the 
leads  brought  up  through  the  center  of  the  coils  except 
on  lines  whose  voltage  is  less  than  5000  volts. 

The  fact  that  lead  covered  cables  have  about  the 
same  limitation  of  current  capacity  renders  the  three- 
phase  reactor  especially  applicable  to  systems  which 
distribute    underground.     A    very    interesting    installa- 


tion of  this  type  of  reactors  is  to  be  found  at  Cleveland, 
where  a  total  of  over  60  units  have  been  in  successful 
operation  on  the  system  of  the  Cleveland  Electric 
Illuminating  Company  for  something  over  two  years. 
The  rating  of  these  coils  is  119  kv-a.,  200  amperes,  198 
volts  drop  per  phase  on  a  three-phase,  60  cycle,  1 1  400 
volt  circuit. 


ich<mica3  Comtraciioii  of  Wnco.i'  VVhooi 


Di'uvoji  Aii:')i'naix)rs 


A  WATER  WHEEL  carrying  full  load  runs  with 
a  normal  peripheral  speed  of  about  half  the 
spouting  velocity  of  the  water.  At  zero 
load,  however,  if  the  governor  fails  to  operate,  the  speed 
of  the  water  wheel  will  increase  considerably.  Hence, 
alternators  driven  by  reaction-type  turbines  are  de- 
signed for  an  overspeed  of  approximately  85  percent, 
and  whenever  possible  are  tested  at  the  specified  over- 
speed  at  the  factory  to  insure  satisfactoiy  balance  and 
to  guard  against  defects  in  materials.  Impulse  wheels 
are  usually  designed  with  a  lower  ratio  of  normal  peri- 
pheral speed  to  water  velocity  and  may  require  that  the 
rotors  be  built  for  '^iverspeeds  up  to  loo  percent. 

An  overspeed  run  is  usually  maintained  for  about 
one  minute.  Nothing  is  to  be  gained  by  running  the 
machine  for  a  longer  period  at  maximum  overspeed,  as 
any  defects  would  show  up  at  once,  and  it  does  not  seem 
good  judgment  to  submit  a  machine  to  abnormal 
stresses  any  longer  than  necessary. 

Rotors  are  designed  to  have  a  reasonable  factor  of 
safety  throughout  when  running  at  the  maximum  over- 
speed.  The  shafts  are  carefully  figured  for  stress  and 
deflection,  taking  into  account  the  critical  speed.  The 
spiders  are  pressed  or  shrunk  onto  the  shafts  with 
proper  allowance  to  maintain  a  tight  fit  when  running 
at  overspeed. 

SPIDERS 

Small  rotors  up  to  about  55  in.  diameter  have 
spiders  built  up  of  1/16  inch  sheet  steel  laminations,  as 
shown  in  Fig.  i.  To  insure  the  maximum  possible  uni- 
formity of  material,  each  lamination  is  revolved  one 
pole  pitch  relative  to  the  previous  lamination  during 
assembly.  The  dovetail  slots  receiving  the  poles  are 
punched,  and  drifts  are  used  in  several  of  these  dove- 
tail slots  during  the  assembly  to  assist  in  building  up 
the  punchings  as  evenly  as  possible.  The  laminations 
are  held  together  axially  by  pressed-in  rivets  with  heads 
spun  over  on  each  end.  The  bore  and  keyway  for  re- 
ceiving the  shaft  are  machined  after  the  spider  is 
assembled. 

For  rotors  of  meduim  size  from  55  up  to  about  150 


K.  MATTiM  \\ 

rower  Engineering  Depurlmenl, 
Westinghouse  Electric  &  Mfg.  Company 

in.  diameter,  cast  s.etl  spiders  are  ordinarily  used,  as 
shown  in  Fig.  2.  The  castings  are  annealed  and  in- 
jpected  for  blowholes  and  other  imperfections.  If  ap- 
parently satisfactory,  they  are  carefully  tested  for  ulti- 
mate strength,  elastic  limit,  elongation  and  reduction  of 
area  by  means  of  test  coupons  cast  integral  with  the 
rotor  spider.  During  the  process  of  machining,  the 
casting  is  again  carefully  inspected  for  seams,  cracks 
and  similar  defects.  The  dovetail  slots,  by  which  the 
poles   are   held    in   position,   are   finished   with    milling 


"ii<t»-t'< 


FIG.    I— SPIDER  BUILT  VP  OF    l/lC   INCH    SHEKT   STEEL   LAM1\-.\TI0NS 

cutters  to  secure  the  greatest  degree  of  accuracy 
possible  on  the  anyles,  fillets,  etc.  It  would  be  cheaper 
to  slot  out  these  dovetails,  but  with  this  process  there 
would  be  a  possibility  of  imperfect  fitting,  sharp  fillets 
and  injurious  tool  marks. 

For  very  high  speeds,  this  construction  would  re- 
quire a  rim  of  such  depth  that  the  casting  might  be 
unsafe,  since  proper  annealing  would  be  difficult  with 
ordinary  foundiy  practice.  In  such  cases  a  plate  spider 
is  resorted  to,  as  shown  in  Figs.  3  and  4,  which  is  built 


26 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


up  of  hot-rolled  open-hearth  steel  plates  approximately 
two  inches  thick.  Each  slab  from  which  the  plates  are 
cut  is  tested  for  physical  properties  by  bending  and  ten- 
sion tests,  the  test  specimens  being  taken  from  the  worst 
place   on   the    slab.     The    individual    plates    are    rough 


FKi.    2 — C.\ST    STEEl.    SPIDER    FOR    MEDIUM    SIZE    ROTORS 

turned,  and  faced  on  the  sides.  They  are  marked  with 
regard  to  the  direction  of  rolling  and  the  top  of  the 
slab  and,  while  assembling,  each  plate  is  revolved  one 
pole  pitch  from  the  preceding  one.  The  plates  are 
clamped  together  with  throughbolts,  a  number  of  which 
are  fitted  into  reamed  holes. 

For  large  spiders  requiring  deep  rims,  above  150 
in.  diameter,  where  thick  rolled  steel  plates  are  not  ob- 
tainable, or  where  the  spider  would  be  too  large  for 
shipment,  a  laminated  spider  rim  is  used,  as  shown  in 
Fig.  5.  These  laminations  consist  of  1/16  in.  sheet 
steel  held  to  the  cast  wheel  spider  by  dovetails  fitted 
closely  into  milled  dovetail  slots  on  the  end  of  the  spider 
arms.  The  laminations  are  clamped  together  between 
heavy  end  plates  with  throughbolts  of  such  a  size  as 
to  make  reaming  unnecessary.  The  joints  between  the 
laminations  are  staggered  in  as  many  axial  planes  as 
practicable,  to  obtain  the  maximum  possible  strength. 

Large  spiders,  greater  than  180  in.  diameter, 
must  be  split  for  shipment.  Spiders  with  laminated 
rims  are  held  together  with  bolts,  the  rim  and  poles 
being  assembled  at  destination.  Spiders  with  cast  rims 
are  fastened  together  with  shrink  links  in  the  rim  and 
bolts  through  the  hub;  such  rotors  can  usually  be 
shipped  with  most  of  the  poles  assembled  at  the  factory. 

FIELD  POLES 

Field  poles  are  built  up  of  1/16  in.  steel  lamina- 
tions held  together  either  by  rivets  or  by  throughbolts 
which  clamp  the  punchings  tightly  between  end  plates. 
The  nuts  of  these  throughbolts  are  countersunk  into  the 
end  plates.  The  upper  coil  supports  on  the  sides  of  the 
poles  are  used  to  hold  the  field  coil  ends  in  place  against 
centrifugal  force.     They  are  either  riveted  to  the  pole 


tips  or  else  are  integral  with  the  end  plates.  The  lower 
coil  supports  are  commonly  made  hollow  so  that  metal 
can  be  poured  into  specially  provided  pockets  when 
found  necessary  in  order  to  secure  proper  static  or 
dynamic  balance.  These  coil  supports  are  fastened  to 
the  spider  by  bolts  and  are  provided  with  slots  so  that 
any  radial  play  that  may  develop  in  any  field  coil,  after 
the  overspeed  test,  can  readily  be  taken  up.  Each  pole 
is  provided  with  a  dovetail  which  fits  snugly  into  the 
dovetail  slot  on  one  side  and  leaves  a  space  for  the  in-' 
sertion  of  two  tapered  steel  keys  on  the  other  side.  The 
poles  are  fastened  to  the  spider  by  driving  the  keys  with 
a  force  sufficient  to  give  a  pressure  somewhat  greater 
than  that  due  to  the  centrifugal  force  of  the  assembled 
[>(?le  and  field  coil  during  the  overspeed  test.  The  keys 
;',re  then  cut  off  flush  v.ith  the  spider  rim. 

A  slight  saving  in  rim  depth  may  sometimes  be 
obtained  by  using  two  or  more  dovetails  per  pole.  This 
practice  is  not,  however  to  be  generally  recommended, 
as  the  dovetails  may  become  unequally  loaded,  due  to 
slight  inaccuracies  in  the  machining  or  unequal  driving 
of  the  dovetail  keys.  These  disadvantages  can  be 
somewhat  alleviated  by  partially  splitting  the  pole  body 
into  as  many  sections  as  there  are  dovetails  per  pole. 


FIELD  COILS 


Wherever  possible,  field  windings  are  made  oi 
copi)er  strap  wound  on  edge,  as  this  makes  a  strong 
coil.     Where  the  voltage  is  too  high  to  permit  the  use 


FLG.    3 — PI_\TE    SPIDER    FOR    HIGH    SPEED    ROTORS 

of  strap,  insulated  wire  or  ribbon  is  used,  the  latter 
being  wound  on  edge.  These  coils  are  given  a  bakelite 
treatment 'which  improves  their  insulation  characteris- 
tics and  makes  them  stronger  mechanically.  On  high- 
speed machines,  and  especially  on  those  with  long  cores. 


January,  192 1 


THE  ELECTRIC  JOURNAL 


27 


it  often  becomes  necessary  to  hold  the  coils  in  place 
with  coil  braces  to  prevent  them  from  spreading  out 
under  the  action  of  centrifugal  stresses. 

DOVETAIL  TESTS 

Extensive  tests  have  recently  been  made  to  deter- 
mine the  comparative  strength  of  different  shapes  of 
dovetails,  as  well  as  to  see  how  the  actual  test  results 


dovetail  slots  were  tested  with  dovetails  of  such  size  as 
to  bring  about  failure  of  the  slots  without  changing  the 
form  of  the  dovetails.  Check  tests  were  made  on  regu- 
lar tension  test  pieces  which  were  cut  from  the  edges  of 
the  plates  of  which  the  dovetail  slots  were  made.  The 
elastic  limit  was  determined  by  an  extensometer.  From 
these  tests  the  following  conclusions  were  drawn: — 

a— There  was  no  marked  difference  in  strength  per  run- 
ning inch  between  the  0.7S  '"■  long  dovetail  and  the  ones 


FIG.    4 PL.\TE    SPnJER    BUILT    UP    OF    IIOT-KUI.LEL)    OPEN-HEARTH 

STEEL    PLATES 

compared  with  the  calculated  strength  of  the  dovetails 
and  slots,  and  particularly  to  determine  whether  it  is 
necessary    to    combine    stresses    in    different    planes    in 


FIG.    5 — LAMINATF.U    .SPUIEK    Kl.M     HUILT    UP    OF    1/16    l.\CH    .SHEET 
STEEL 

of  1.5  in.  length.  The  test  results  can,  therefore,  be  con- 
sidered as  representative  lor  dovetails  and  dovetail  slots  of 
greater  length,  such  as  are  ordinarily  used  in  practice. 

b — All  punched  dovetails,  without  end  plates,  failed  by 
Ijuckling,  as  shown  in  Figs.  6  and  8.  There  was  no  differ- 
incc  in  strength  between  the  one  rivet  and  two  rivet  dove- 


FIG.    6 — LAMINATED 

DOVETAIL      FAILED      n\ 

BUCKLING 


FIG.     7 — LAMINATED 

DOVETAIL     WITH 

END     PLATES 


FIG.    8 — ISO    DEGREE 

LAMI.NATED      DOVETAIL 

FAILED    BY 

BUCKLING 


FIG.    9 — UPS    OF    6o 
DEGREE     DOVETAIL 
SLOT     TURNED      UP 


FIG.       to — 150      DEGREE 
DOVETAIL    SLOT 


making  calculations.  For  instance,  should  bending  and 
tension  be  again  combined  with  shear?  Seven  different 
pulling  tests  were  made  with  samples  of  the  dimensions 
shown  in  Table  I,  samples  i  to  5  being  dovetails,  and 
samples  6  and  7  dovetail  slots.  Samples  /  to  5  were  built 
up  of  1/16  in.  steel  laminations  and  samples  6  and  7 
were  made  of  hot  relied  open  hearth  steel  plate.  The 
dovetails  were  pulled  while  engaged  in  dovetail  slots  of 
such  proportions  as  10  make  the  dovetails  fail  first.  The 


tails.  The  dovetail  with  end  plates  failed  by  tearing,  as 
shown  in  Fig.  7.  It  began  to  yield  with  about  the  same 
pull  as  the  dovetails  without  end  plates. 

c — The  results  obtained  compared  closely  with  calcula- 
tions, and  showed  that  the  assumed  plane  of  greatest  stress 
was  correctly  chosen,  and  that  stresses  in  planes  at  different 
.ingles,  such  as  bending  and  shear,  should  be  combined  in 
order   to   get   the   nia.ximum    resultant   stress. 

d — There  was  no  apparent  difference  in  strength  be- 
tween the  two  shapes  of  dovetails.  For  a  given  pull  the 
60  degree  dovetail  takes  up  approximately  25  percent  less 
depth  and  about  the  same  amount  more  in  width  than  the 
150  degree  dovetail.     Thus   it   was  thought   best   to   retain 


28 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


the  present  standard  shape,  namely  the  60  degree  dovetail, 
especially   since    the    150   degree   shape   has   certain   disad- 
vantages, such  as  narrower  keys  and  smaller  fillets,  as  well 
as  the  required  centering  of  the  poles  circumferentially. 
SPECIAL  DESIGNS 

Rotors  of  somewhat  higher  peripheral  speeds  can  be 
built  by  resorting  to  the  use  of  removable  pole  tips.     In 


TABLE   I- 


-DIMENSIONS   OF   TEST    DOVETAILS    AND 
SLOTS 


Sample 

Degrees 

Depth 
In. 

Width 
In. 

Length 
In. 

Rivets 

See 
Fig. 

I 

60 

2 

35 

IS 

I 

2 

60 

2 

3-S 

1-5 

End 

6 

3 

60 

2 

3.S 

i.S 

Plates 

7 

4 

60 

2 

3S 

0.75 

I 

5 

ISO 

2^8 

m 

1-5 

2 

8 

6 

60 

2 

3-5 

i-S 

9 

7 

ISO 

27/8 

27/8 

1-5 

10 

this  design  the  rotor  spider  and  pole  bodies  are  integral, 
and  are  made  of  one  solid  steel  casting,  or  several  cast 
or  forged  slabs,  or  of  the  required  number  of  rolled  steel 
plates  properly  bolted  together.  The  pole  tips  can  be 
held  on  in  various  ways.  The  most  common  arrange- 
ment is  that  shown  in  Fig.  11,  where  the  tips  are 
fastened  to  the  pole  body  by  a  number  of  screws  or 
bolts,  which  are  sometimes  made  of  nickel  steel.  In 
Fig.  12  is  shown  a  special  arrangement  in  which  the 
pole  tip  consists  of  a  number  of  steel  plates  which  are 
inserted  into  recesses  in  the  outer  part  of  the  plates 
which  form  the  spider  and  pole  bodies.  These  pole  tips 
are  held  to  the  pole  bodies  by  throughbolts.  Another 
method  of  fastening  the  pole  tips  to  the  pole  bodies  is 


the  pole  body.  It  is  either  screwed  into  the  pole  body, 
as  illustrated  in  Fig.  13,  or  is  provided  with  a  tapped 
hole  and  screwed  ove-  the  pole  body,  the  pole  tips  in  this 
case  forming  part  of  the  body.  A  laininated  outer  pole 
face  may  be  used  with  the  construction  shown  in  Fig. 
13,  which  is  one  solid  piece  of  steel,  but  this  is  not  possi- 
ble with  the  poles  shown  in  Figs.  11  and  12,  which  are 


FIG.     12 — STEEL    PLATES    OF    POLE    TIP    INSERTED    INTO    RESESSES    OF 
BODY   PLATES 

made  up  of  steel  plates.  This  pole  face  may  be 
fastened  to  the  solid  part  of  the  pole  tip  by  dovetails, 
as  shown  in  Fig.  13. 

All  these  constructions  are  considerably  more  com- 
plicated and  consequently  more  expensive  than  the 
ordinary  designs  with  dovetailed  poles.  They  also 
require  more  machining  of  a  special  nature  and  must, 
therefore,  undergo  more  painstaking  inspection.  In  the 
case  of  steel  castings  or  thick  cast  slabs,  the  danger  of 
faulty  material  remaining  undetected  is  particularly 
great,  on  account  of  the  large  size  and  intricate  shape 
of  the  castings  involved.  This  danger  is,  of  course, 
lessened  in  designs  using  forged  slabs  or  plates,  which 


-POLE    TIP    FASTENED    TO    POLE    BODY     WITH     NICKEL    STEEL 
BOLTS 


FIG.    13— POLE  TIP   SCREWED   INTO   POLE  BODY 


shown  in  Fig.  13.  For  this  arrangement  the  pole  body  involve,  however,  much  more  machining.  These  de- 
must  be  either  round  or  square  or  nearly  so.  The  pole  signs  have  been  used  abroad  more  frequently,  probably 
tip  is  provided  with  a  very  course  thread  of  a  diameter  on  account  of  the  greater  amount  of  skilled  help  avail- 
about  equal  to  two-thirds  of  the  diameter  or  width  of  ;ible  at  reasonable  prices  there. 


Typical  Rolay  C(Oimocilo:n^ 

LEWIS  A.    lERV'tN 

Switchboard  Engineering  Dept., 
Westinghousc  Electric  &  Ml'g.  Company 

During  1908  and  1909  a  series  of  articles  was  published  in  the  Journai.  on  "Meter  and  Relay  Connec- 
tions" by  Mr.  H.  W.  Brown.  This  series  has  been  so  widely  useful  that  it  was  considered  advisable  to 
revise  it,  in  view  of  recent  developments,  in  a  series  of  articles  which  would  represent  the  best  modern 
and  up-to-date  switchboard  practice.  As  it  was  hardly  possible  for  an  author  to  revise  the  work  of  another 
done  a  decade  previously,  the  result  has  been  an  entirely  new  series  of  articles  on  this  important  subject. 
The  revised  articles  covering  "Alternating-Current  Switchboard  Meter  Connections,"  which  were  prepared 
by  Mr.  J.  C.  Group,  were  published  in  the  Journal  during  1920.  With  this  issue  is  begun  a  series  by  Mr. 
Lewis  A.  Terven  on  "Relay  Connections"  which  covers  the  more  common  applications  of  this  important 
piece  of  switchboard  apparatus.  In  general  Mr.  Terven  employs  the  same  conventional  representations 
for  switchboard  equipment  and  the  same  assumptions  with  regard  to  polarity,  etc.,  that  were  used  both  by 
Mr.  Brown  and  Mr.  Group,  and  these  are  not  repealed  here,  as  they  are  given  in  full  in  the  Journai,  for 
January  1920.     (Ed.) 


A  .SHORT-CIRCUIT  or  other  electrical  disturb- 
ance arises  too  rapidly  for  a  switchboard  at- 
tendant to  operate  switches  in  time  to  prevent 
serious  interruptions  of  service  and  the  possibility  of 
heavy  damage  to  the  generating  and  transforming 
equipment.  .Some  means  is  necessary,  therefore,  of 
automatically  clearin'.;-  the  .system  of  such  disturbances 
without  the  intervention  of  the  operator.  Circuit 
breakers  for  large  modern  power  stations  are  so  bulky 
that  a  large  force  's  required  to  actuate  them.  A  relay 
is,  therefore,  necessary  between  the  circuit  in  which  the 
trouble  occurs  and  the  circuit  which  provides  the  power 
for  actuating  the  cuxuit  breaker  mechanism. 

To  clear  an  electrical  disturbance  on  a  large  sys- 
tem with  the  minimum  interruption  of  power  supply,  it 
is  essential  that  certain  circuit  breakers  should  operate 
in  a  definite  sequence,  requiring  a  delayed  action  in  the 
relay,  which  may  amount  to  several  seconds,  and  yet 
must  be  capable  of  adjustment  to  within  a  small  frac- 
tion of  a  second.  It  is  further  desirable  that  a  signal 
of  some  sort  should  inform  the  switchboard  attendant 
of  the  automatic  action  that  has  taken  place,  in  order 
that  he  may  restore  complete  service  as  promptly  as 
possible.  Relays  are  also  necessary  for  a  variety  of 
automatic  functions  involved  in  normal  operation. 

The  relay  is  thus  one  of  the  most  important  pieces 
of  switchboard  apparatus.  It  can  be  built  in  a  variety 
of  forms  and  is  adapted  to  a  wide  variety  of  applica- 
tions. The  purpose  of  this  article  is  to  set  forth  the 
use  of  protective  and  other  similar  relays  and  to  give 
diagrams  illustrating  the  methods  of  relay  installation. 
It  is  frequently  advisable  to  show  relay  connections  as 
seen  from  the  front  of  the  instrument,  because  many 
relays  are  mounted  on  the  rear  of  the  switchboard, 
upon  bases  provided  for  the  purpose,  and  when  con- 
necting the  switchboard,  the  workman  should  have  a 
front  connected  diagram  of  the  relays  upon  a  rear  con- 
r.ected  diagram  of  the  switchboard  proper.  A  dotted 
outline  of  the  base  indicates  the  shifting  lines  for  the 
front  and  rear  views.  Descriptions  of  the  actual  relays 
themselves  are  not  given,  but  can  be  obtained  from 
manufacturer's  catalogues  or  from  various  descriptive 
articles. 


The  subject  v\ill  be  divided  into  live  very 
loose  headings,  treating  first  of  direct-current  relays, 
next  of  overload  relays,  then  of  reverse  power  and  re- 
verse current  relays,  sundry  alternating-current  relays, 
and  finally,  general  applications.  Since  the  field  of  one 
relay  invariably  encroaches  upon  the  field  of  some  other 
relay,  a  rigid  classification  would  be  difficult  to  make. 

Direct-current  relays  and  direct-current  auxiliary 
relays  are  discussed  first  because  they  are  used  in 
many  cases  in  connection  with  alternating-current 
switches,  they  are  also  much  easier  to  understand,  and 
consequently  their  treatment  leads  up  to  the  comprehen- 
sion of  the  more  -"omplicated  alternating-current  relay 
schemes. 

DIRECT-CURRENT  RELAYS 

Fig.  I  illustrates  a  general  utility  circuit  opening 
relay  whose  contacts  are  mechanically  latched  open 
upon  electrical  operation.  The  latch  may  be  released 
by  hand,  or  electrically  by  means  of  an  unlatching  coil, 
as  shown.  In  this  particular  diagram  the  relay  is  used 
for  bell  alarm  purposes,  the  operation  being  as  fol- 
lows:— Whenever  the  oil  circuit  breaker  operates  auto- 
matically, because  of  overload,  current  will  be  drawn 
from  the  positive  bus  through  the  unlatching  coil  to  the 
relay  bus  and  from  there  through  the  overload  relay 
contact,  trip  coils  and  pallet  switch  to  negative  bus.  The 
contacts  of  the  bell  alarm  relay  will  close  by  gravity 
after  being  unlatched  and  the  bell  circuit  is  thereby 
established.  The  bell  circuit  is  opened  when  the  push 
button  switch  is  pressed  by  the  switchboard  attendant, 
causing  current  to  flow  through  the  latching  coil,  this 
operation  raises  the  contacts  of  the  relay.  The  bell 
will  not  ring  upon  operation  of  the  circuit  breaker  by 
means  of  the  control  switch.  Furthermore,  if  other 
circuit  breakers  are  installed,  using  the  same  bell  alarm, 
the  current  required  for  tripping  the  circuit  breakers 
automatically  must  pass  through  the  unlatching  coil,  or 
from  the  positive  bus  to  the  relay  bus.  This  feature  is 
objectionable  because  circuit  breakers  are  not  all  de- 
signed to  take  the  same  tripping  current,  and  further- 
more, in  case  of  any  open  circuit  between  the  positive 
rnd   the  relay  bus,  all   of  the   circuit  breakers  on  the 


30 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  1 


system  would  be  without  relay  protection.  These  ob- 
jections can  be  overcome  by  the  use  of  a  bell  alarm  re- 
lay whose  unlatching  coil  is  of  the  parallel  type  instead 
of  requiring  a  series  circuit  as  shown  in  Fig.  i. 

In  Fig.  2  such  a  bell  alarm  relay  is  shown  with  the 
unlatching  or  release  coil  across  the  direct-current  con- 
trol circuit.  This  relay  is  of  the  same  type  as  the  one 
just  described  with  the  addition  of  an  auxiliary  con- 


FIG.     I — CONNECTIONS    FOR    l^ENEUM.    ITILITV    CIRCUIT    OPKNINc 
WrX.W 


tact  above  the  main  contact,  the  auxiliary  contact  being 
closed  when  the  main  contacts  are  open  and  vice-versa. 

In  normal  operation  the  main  contacts  of  the  bell 
alarm  relay  are  open  and  the  auxiliary  contact  is  closed. 
Should  an  overload  lelay  operate,  causing  the  circuit 
breaker  concerned  to  be  opened,  at  the  time  of  tripping 
the  circuit  breaker  the  overload  relay  also  energizes  a 
third  contact,  as  shown  in  the  enlarged  diagram  of  the 
relay  itself.  Current  from  the  positive  control  wire  will 
then  flow  through  the  third  direct-current  contact  of 
the  overload  relay,  through  a  resistance  to  the  release 
coil  and  through  the  auxiliary  contact  on  the  relay  to 
the  negative  control  bus,  i^eleasing  or  unlatching  the  re- 
lay plunger  which  falls  to  position,  closing  the  main 
contacts  and  opening  the  auxiliary  contact  above. 
The  bell  circuit  thus  established  will  continue  to  ring 
until  the  reset  coil  is  energized  by  means  of  the  push 
button  shown  below  the  relay.  It  will  be  observed  that 
the  operation  of  the  bell  alarm  relay  is  unaffected  by 
the  amount  of  current  taken  by  the  trip  coil  of  the  cir- 
cuit breaker,  and  furthermore,  that  in  case  of  failure 
in  the  bell  alarm  circuit,  the  automatic  operation  of 
any  circuit  breaker  would  remain  the  same  as  before. 

The  circuit  breaker  controllers  used  with  this  dia- 
gram are  worthy  of  mention.  The  lamp  cut-off  con- 
tact is  operated  by  means  of  the  handle  of  the  con- 
troller, which  will  remain  mechanically  in  position  when 
pulled  out,  opening  the  lamp  circuit  of  the  green  light. 
The  handle  can   only  be  pulled  out   when  the   circuit 


breaker  is  in  the  off  position  and  thus  the  red  light  will 
already  be  out. 

In  case  of  the  controllers  for  the  double  bus  sys- 
tem, where  it  is  required  that  the  overload  relays  will 
operate  either  or  both  circuit  breakers  which  may  be 
closed,  an  additional  segment  is  placed  upon  the  con- 
troller drum,  its  position  being  such  that  when  the  con- 
troller is  in  the  position  of  rest,  i.e.,  free  from  the  hand 
of  the  operator,  this  segment  will  connect  the  relay  con- 
tacts to  the  circuit  of  the  trip  coil  of  the  circuit  breaker. 
Any  number  of  circuit  breakers  can  have  their  trip  coils 
in  parallel  in  this  manner,  and  whenever  manual  opera- 
tion is  required,  and  the  controller  is  moved  over  by 
hand,  the  contacts  of  the  controller  first  clear  the  seg- 
ment which  connects  the  relay  circuit  with  the  trip 
coils,  thus  allowing  any  circuit  breaker  to  be  operated 
by  hand  without  all  the  others  of  the  system  coming 
out  at  the  same  time. 

Attention  is  also  called  to  the  small  internal  relay 
in  the  direct-current  circuit  of  the  alternating-current 
overload  relay  shown  in  the  enlarged  view.  The  trip 
current  of  the  circuit  breaker,  flowing  through  the  con- 
tactor switch  coil,  causes  its  plunger  to  rise  until  the 
three  upper  contacts  are  short-circuited  by  the  disc  as 
indicated.  Clearly,  once  this  relay  closes  its  con- 
tacts, the  removal  of  the  alternating-current  over- 
load will  have  no  effect  upon  releasing  the 
plunger,  because  when  the  disc  closes  the  upper  con- 
tacts, the  current  in  the  direct-current  circuit 
still  flows  through  the  contactor  switch  coil.  This 
feature  of  the  operation  of  the  relay  is  not  objection- 
able, because  the  trip  circuit  can  be  and  should  be 
opened  by  means  of  the  pallet  or  auxiliary  switch  of 


Qell  RtUy  D  C  Comrol  Bo»  .ind  B«tl 


■-<^: 


I-IG.    2— BELL    ALAR.M    RELAY    WITH    RELEASE   COIL   CONNECTED 
ACROSS  THE  DIRECT-CURRENT  CONTROL  CIRCUIT 

The  lamp  cut-off  contact  is  operated  by  the  circuit 
breaker  control  switch.  A  small  internal  relay,  in  the 
direct-current  circuit  of  the  overload  relay,  prevents  burn- 
ing the  overload  contacts. 

the  circuit  breaker,  i.nd  all  burning  of  the  contacts  of 
the  overload  relays  is  thus  avoided.  Furthermore,  the 
internal  contactor  switch,  due  to  its  latching-in  process, 
will  prevent  the  burning  of  the  more  delicate  overload 


January,  192 1 


THE   ELECTRIC  JOURNAL 


31 


contacts,  due  to  an  overload  which  is  barely  sufticient 
to  cause  the  contacts  to  close  or  perhaps  to  chatter. 

If  it  is  required  to  use  separate  control  circuits  for 
the  circuit  breaker  belonging  to  the  duplicate  bus  in 
Fig.  2,  the  extra  segment  on  the  controllers  cannot  be 
employed  for  the  purpose,  but  auxiliary  multicontact 
relays  as  shown  later  must  be  supplied,  the  object  being 
to  keep  the  control  circuits  apart.  The  amount  of  cur- 
rent drawn  through  the  overload  relay  in  order  to  trip 
a  circuit  breaker  should  be  of  sufficient  magnitude  to 
close  the  contactor  circuit,  but  this  requirement  is  easy 
t(i  meet  through  design  of  the  circuit  breaker  trip  coils 
or  through  design  of  the  contactor  switch  coil  itself. 
The  signal  lamps  may  be  connected  to  another  circuit 
apart  from  the  control  bus,  and  for  that  reason  the 
lamp  cut-off  contact  is  isolated  from  the  main  func- 
tions of  the  control  switch. 

The  same  type  of  relay  shown  in  Figs,  i  and  2  is 
used  in  Fig.  3  for  a  trip  free  relay.  In  addition  to  the 
reset  coil,  the  unlatchmg  coil,  the  main  contacts,  and  the 
auxiliary  contact,  a  dashpot  is  shown  which  gives  a 
time  element  to  the  opening  of  the  main  contacts  when 
current  flows  in  the  reset  coil.  The  object  of  the  trip 
free  relay  is  to  render  a  plain  automatic  circuit 
breaker  fully  automatic. 

The  closing  current  of  the  oil  circuit  breaker,  in- 
stead of  flowing  through  the  contacts  of  the  control 
switch  and  directly  through  the  closing  coil  to  the  con- 
trol bus,  flows  throus^ii  the  coil  of  a  control  relay  which, 
upon  closing,  allows  current  to  flow  from  the  control 
bus  through  the  closing  coil,  thus  closing  the  circuit 
breaker.  The  reason  for  the  use  of  the  control  relay 
is  that  the  amoimt  of  current  taken  to  close  most  types 
of  solenoid  operated  circuit  breakers  is  too  great  to  be 

D  C  Control  Bus 


FIG.   3 — BELL    AI.ARAl    k|- LAY    USED   AS    A    TRIP  FREE  RELAY 


interrupted  successfully  by  the  control  switch,  and 
furthermore,  it  is  expensive  to  carry  heavy  conductors 
from  the  switchboard  to  the  circuit  breaker  for  closing 
purposes;  whereas  the  current  in  the  coil  of  the  con- 
trol relay  is  small.  The  control  relay  is  usually  mounted 
near   the    oil     circuit    breaker,     frequently    upon    the 


mechanism  of  the  breaker  it.self,  and  it  is  provided  with 
a  magnetic  blowout  coil  which  aids  materially  in  inter- 
rupting the  circuit  of  the  closing  coil.  Even  though 
the  amount  of  current  taken  by  the  closing  coil  may 
not  be  high,  the  inductive  character  of  the  circuit  is 
such  that  a  very  large  spark  or  flash  results  upon  in- 


EI(..    4 — TIME    ELEMENT    RELAY 

I'or  giving  a  definite  time  to  ;i 


LONNEITIONS 

signal   from   a   horn. 


terrupting  this  circuit,  and  for  that  reason  control  re- 
lays are  used,  even  with  rather  small  circuit  breakers. 
A  circuit  breaker  is  considered  to  be  full  automatic 
when  the  operator  is  powerless  to  keep  it  closed  in  case 
of  an  automatic  tripping  impulse.  The  trip  free  relay 
shown  in  Fig.  3  accomplishes  this  end  by  interrupting 
the  closing  circuit  of  the  circuit  breaker  after  the  latter 
has  been  closed  and  latches  the  closing  circuit  open  until 
the  controller  has  been  moved  by  the  operator  into  the 
"trip"  position,  thus  causing  the  trip  free  relay  to  un- 
1.1  tch  and  close  its  main  contacts.  Tracing  the  circuit 
through,  the  closing  current  for  the  circuit  breaker  is 
seen  to  flow  from  the  positive  bus  through  the  control 
switch,  the  coil  of  the  control  relay,  and  the  main  con- 
tacts of  the  trip  free  relay,  to  negative.  When  the  cir- 
cuit breaker  closes  the  pallet  switches  rise  to  the  upper 
position,  causing  a  current  from  positive  to  flow 
through  the  reset  coil  of  the  trip  free  relay  and  the 
main  contacts  to  negative,  which  results  in  opening  the 
main  contacts  after  a  definite  time,  determined  by  the 
setting  of  the  dashpct  shown  in  position  at  the  bottom 
of  the  plunger  of  vhe  relay.  This  relay  opens  its  own 
circuit, 'leaving  the  reset  coil  disconnected  from  the  cir- 
cuit. Once  the  main  contacts  of  the  trip  free  relay 
are  open  it  is  impossible  to  pass  current  through  the 
closing  coil  of  the  control  relay,  and  hence  the  circuit 
breaker  is  subject  to  the  action  of  the  overload  relays 
shown  connected  to  the  current  transformers  on  the 
main  line.  Should  the  latter  operate,  positive  control 
current  will  pass  through  the  overload  relay  contacts, 
the  trip  coils,  and  the  pallet  switches  (now  in  the  upper 
position),  to  negative,  thus  tripping  the  circuit  breaker. 
The  alarm  bell  will  be  put  into  circuit  from  the  posi- 
ti\e  to  the  bell,  through  the  lower  contacts  of  the  right 


2,2 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.   I 


hand  pallet  switch  and  finally  through  the  auxiliary  con-  filament  of  the  red  lamp,  the  circuit  breaker  wdl  have 
tact  of  the  trip  free  lelay  to  negative,  the  bell  continuing  full  control  voltage  impressed  upon  its  trip  coil.  The 
to  ring  until  the  trip  free  relay  is  reset.  This  latter  chances  of  such  an  occurrence  are  very  remote,  and  are 
operation  is  performed  by  moving  the  controller  into  not  usually  guarded  against,  except  where  absolute 
the  trip  position,  which  causes  positive  control  current  continuity  of  service  is  desirable.  In  such  a  case,  sepa- 
to  pass  through  the  latch  release  coil  to  negative,  al- 
lowing the  main  contacts  of  the  trip  free  relay  to  close. 
Should  the  circuit  breaker  be  tripped  by  means  of 
the  control  switch  the  bell  will  not  ring,  because  at  the 
time  the  circuit  is  made  through  the  tripping  coil,  the 
circuit  is  also  established  in  the  latch  release  coil  of 
the  trip  free  relay  and,  due  to  the  diflference  in  inertia 
of  the  apparatus  concerned,  the  trip  free  relay  will 
operate  before  the  circuit  breaker  throws  its  pallet 
switches  into  the  open  position.  In  this  diagram  the 
red  and  green  lights  both  bum  through  the  trip  coil 
of  the  oil  circuit  breaker.  This  arrangement  has  been 
found  satisfactory,  as  the  small  drop  in  the  trip  coil 
does  not  affect  the  brilliancy  of  the  lamps  appreciably 


rate  lamp  wires  are  run  between  the  switchboard  and 
the  circuit  breaker,  or  a  resistance  is  used  in  series  with 
the  lamp. 

In  Fig.  4  this  same  useful  relay  is  shown  connected 
for  giving  a  definite  time  to  the  blast  from  a  horn  for 
signal  purposes.  Thus,  should  the  operator  from  the 
switchboard  gallery  push  a  button  notifying  the  atten- 
dant on  the  floor  of  incoming  signals,  the  horn  would 
give  a  definite  blast,  the  relay  opening  the  circuit  of  the 
horn  after  the  time  interval  had  elapsed,  although  cur- 
rent would  still  flow  in  the  reset  coil  of  the  relay.  Upon 
pushing  the  three-way  switch  in  answer  to  the  switch- 
board attendant,  the  main  floor  operator  resets  the  re- 
lay of  the  horn  and  at  the  same  time  energizes  a  simi- 


nor  IS  the  current  of  the  lamps  of  sufficient  magnitude  lar  relay,  which  rings  a  buzzer  in  the  switchboard 
to  trip  the  circuit  breaker.  However,  should  the  cir-  gallerj-,  notifying  the  switchboard  operator  that  the 
cuit  breaker  be  closed  and  a  short-circuit  occur  in  the     signals  have  been  observed. 

Voltage  ^llelattons  m  Direct-Current  ^(ac^U(u;^s 

R.  E.  FERRIS 

Motor  Engineering  Dept., 
W'estinghousc  Electric  &  Mfg.  Company 


WITH  the  ever  increasing  voltage  now  being  used 
in  direct-current  practice,  the  importance  of  a 
careful  analysis  of  the  voltage  relations  in 
all  classes  of  direct-current  apparatus  becomes  of  more 
and  more  importance.  Very  often  a  direct-current  ma- 
chine is  insulated  with  little  regard  to  the  potential  dif- 
ference between  parts,  other  than  to  ground  or  between 
single  coils. 

The  following  investigation  covers  only  the  more 
common  types  of  winding,  but  the  application  of  the 
discussion  and  formulae  to  special  cases  may  easily  be 
made. 

VOLTAGE  TO  GROUND 

The  voltage  to  ground  for  any  type  of  direct-cur- 
rent machine  needs  little  comment,  except  in  so  far  as 
grounded  or  ungrounded  circuits  are  concerned. 

Grounded  Circuits — On  grounded  circuit?,  the 
maximum  voltage  to  ground  is  the  total  voltage  of  the 
apparatus.  If  two  or  more  machines  are  connected  in 
series,  as  on  the  1200,  1500  or  3000  volt  railway  motors, 
then  one  machine  will  be  constantly  subjected  to  the 
total  voltage  at  the  maximum  point,  while  the  others 
will  normally  have  only  half  the  total,  though  under 
certain  conditions,  such  as  surges,  starting,  etc.,  this 
value  may  be  exceeded. 

Ungrounded  Circuits — On  an  ungrounded  circuit, 
the  potential  difference  between  the  terminals  may  be 
considered  as  half  positive  and  half  negative,  the 
grounded   point   being  at   zero   potential.      This   being 


true,  the  voltage  to  ground  on  an  ungrounded  circuit 
will  be  one  half  of  the  terminal  voltage.  But  even  if 
the  circuit  becomes  grounded  in  one  place,  there  will 
only  be  a  momentary  flow  of  current  due  to  the  capacity 
of  the  circuit.  However,  the  moment  an  ungrounded 
circuit  grounds  at  one  point,  it  then  has  all  the  charac- 
teristics of  a  grounded  circuit.  A  more  detailed  ex- 
1  lanation  of  ungrounded  circuits  will  be  given  under 
\oltage  relations  in  field  coils. 

NOMENCLATURE 

Turn-  This  will  be  best  understood  by  reference 
to  Figs.  I  to  4  inclusive. 

Single  Coi/— This  has  an  electrical  significance  and 
includes  all  the  turns  between  commutator  bars  for  a 
multiple  winding  or  the  number  of  turns  between  bars 
divided  by  the  number  of  pairs  of  poles  for  a  two  cir- 
cuit or  series  winding. 

Complete  Coi7— This  has  a  mechanical  significance 
only  and  includes  all  the  single  coils  which  are  insulated 
together  from  ground. 

VOLTAGE  BETWEEN  TURNS 

The  voltage  between  turns  is  equal  to  the  total  volts 
divided  by  the  number  of  turns  in  series.  For  a  mul- 
tiple winding 

"     F,  P  A'v 


K. 


C  T,      

Or  for  series  winding.- 
2  Vt  K,_ 
C  T,      


F.  = 


(/> 


(/a> 


January,  1921 


THE  ELECTRIC  JOURNAL 


33 


Where 

Vt  =  Maximum  volts  between  turns. 

P    =  No.  of  poles. 

C    =:  No.  of  commutator  bars. 

Vi  =  Terminal  volts. 

Ts  =  Turns  per  single  coil. 

Kt  =  Factor  to  obtain  maximum  voltage. 

In  applying  the  above  formulas,  it  is  obvious  that 
when  Tg  becomes  equal  to  i,  Vi  will  be  the  volts  be- 
tween commutator  bars,  and  formula  (2)  Figs,  i  and  2, 
developed  for  the  voltage  between  single  coils  should  be 
used. 

VOLTAGE    BETWEEN    SINGLE    COILS 

The  voltage  between  single  coils  for  both  lap  and 
wave  windings  will  be  the  same  as  the  voltage  between 
commutator  bars. 

K,  P  K, 

V'=  —c — • (^) 

Where,  V^  =  volts  between  single  coils  or  between 
commutator  bars. 

It  is  evident  from  Figs.  5  or  6  that  one  single  coil 
only  is  connected  between  commutator  bars  on  the  lap 
winding,  while  as  shown  by  Fig  7,  the  wave  winding  has 
as  many  single  coils  in  series  between  cominutator  bars 
as  there  are  pairs  of  poles. 


coils  would  not  decrease  directly  as  the  number  of  com- 
mutator bars,  however,  for,  as  shown  in  Fig.  8,  a  field 
form  of  a  commutating  pole  railway  motor,  the  first 
few  bars  on  each  side  of  the  brush  line  have  very  little 
voltage  between  them,  so  that  in  the  case  of  this  motor 
the  leads  from  the  top  and  bottom  coils  could  span  a  \ 
number  of  bars  less  than  they  would  with  a  pitch  wind- 
ing without  changing  the  integration  of  the  curve  to  any 
great  extent.  It  is  evident,  however,  that  if  the  wind- 
ing is  chorded  down  to  such  an  extent  that  the  total 
number  of  turns  will  need  to  be  increased  in  order  to 
generate  the  required  voltage,  the  volts  between  coils  in 
the  same  slot  will  decrease. 

Fig.  7  shows  that  the  leads  from  the  top  and  bottom 
coil  in  the  same  slot  in  the  case  of  a  wave  winding  span 
more  bars  than  the  brushes,  so  that  exactly  the  same 
results  are  obtained  as  in  the  case  of  a  lap  winding.  It 
may  be  stated  in  general  that  with  all  ordinary  chord- 
mg,  especially  on  railway  motors,  the  maximum  voltage 
between  coils  in  the  same  slot  will  not  be  more  than  10 
or  15  percent  less  than  the  generated  voltage. 

VOLTAGE  BETWEEN   COILS  ON   ENDS 

Pitch  Winding — From  Figs.  5  and  9  it  is  evident 


Fll 


SINGLE 
TURN     LAP     OR 
MULTIPLE 
WINDING 


FIG.    2 — SINGLE    TUKN     WAVE    OR    SERIES 
WINDING 


FIG.    3 — TWO-TURN    W.WE    OK    SERIES 
WINDING 


FIG.     4 — TWO 

TURN     LAP     OR 

MULTIPLE 

WINDING 


VOLTAGE   BETWEEN    COMPLETE    COILS   IN    THE   SAME   SLOT 

Pitch  Winding- — It  is  evident  from  Figs.  5  and  9 
that  the  voltage  between  coils  in  the  same  slot  for  either 
a  lap  or  wave  winding  will  alternate  from  zero  to  ap- 
proximately the  maximum  generated  volts.  If  there  is 
only  one  single  coil  per  complete  coil,  and  the  brush 
covers  only  a  little  over  one  commutator  bar,  then  the 
maximum  voltage  will  be  less  than  the  generated  volt- 
age, but  as  the  difference  would  ordinarily  be  small,  it 
may  be  assumed  that  in  all  cases  with  pitch  winding  the 
maximum  volts  between  coils  in  the  same  slot  is  equal 
to  the  generated  volts.  This  maximum  voltage  between 
coils  in  the  same  slot  will  occur  at  the  time  the  coils  are 
in  the  neutral  zone.  In  other  words,  at  the  time  they 
are  being  commutated. 

Chorded  Winding — From  Fig.  6  it  is  evident  that 
the  tendency  of  a  chorded  winding  is  to  give  a  lower 
voltage  between  coils  in  the  same  slot  for  a  lap  wind- 
ing. However,  chording  one  slot  with  a  reasonable 
number  of  slots  and  with  an  ordinary  field  form  would 
give  a  potential  difference  very  little  different  from  the 
pitch  winding.  Comparison  of  Figs.  5  and  6  will  show 
that  the  commutator  bars  spanned  by  the  leads  from  the 
top  and  bottom  coil  are  less  with  the  chorded  winding 
than  with  the  full  pitch  winding.     The  voltage  between 


that  the  voltage  between  the  upper  and  lower  layer  of 
coils  at  the  ends  changes  from  a  maximum,  the  value  of 
which  is,  in  the  case  of  pitch  windings,  always  some- 
v\'hat  less  than  the  voltage  between  coils  in  the  same 
slot,  to  a  minimum  value  of  approximately  zero.  It 
will  also  be  noted  that  the  farther  out  from  the  iron, 
the  less  the  voltage  between  layers.  For  example,  in 
Fig.  5,  the  coils  which  cross  at  a  connect  to  bars  j  and 
6,  or  a  span  of  three  bars.  At  b  the  coils  connect  to 
bars  4  and  6,  or  a  span  of  two  bars.  At  c  the  coils 
connect  to  bars  4  and  5,  or  a  span  of  one  bar.  In  the 
case  of  a  wave  winding  the  same  thing  occurs. 

Chorded  Winding — In  a  wave  winding  which  is 
chorded  to  any  great  extent,  the  voltage  between  coils 
at  the  ends  will  first  increase  to  a  maximum,  the  value 
of  which  is  never  more  than  the  generated  volts,  and 
then  decrease  to  zero.     This  is  shown  in  Fig.  7. 

DOUBLE   COMMUTATOR   MACHINE 

There  are  various  ways  of  arranging  the  windings 
for  a  double  commutator  machine,  but  for  the  present 
discussion  only  that  arrangement  will  be  considered  in 
which  the  first  winding  is  wound  and  connected  com- 
plete to  its  commutator  before  the  second  winding  is 
put  in  place.  ,  With  this  type  of  winding,  the  top  and 
bottom   windings  may  occupy  different  percentages  of 


34 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


the  slot  area,  as  would  be  the  case  if  one  winding  carries 
more  current  than  the  other.  Referring  to  Fig.  12,  in 
which  Ti  =  the  top  coil  of  the  bottom  or  first  wind- 
ing, Bi  =  the  bottom  coil  of  the  bottom  or  first  wind- 
ing, Tj  =  the  top  coil  of  the  top  or  second  winding  and 
B^  =  the  bottom  coil  of  the  top  or  second  winding,  the 


FIG.    5 Fl-LL    PITCH    I.AI>    WINlllM 

S                                         N  . 

I J  I I 


FIG.    6 — CHORDED    LAP    WINDING 


FIG.    7 — CHORDED   RETROGRESSIVE   W.WE    WI.NUING 


voltage  relation  between  T,  and  B^  and  between  7,  and 
B^  has  been  discussed,  but  the  voltage  between  B^  and 
T^  still  remains  to  be  investigated.  A  two  circuit  wind- 
ing only  will  be  considered,  but  of  this  type  of  winding 
two  connections  will  be  discussed,  namely,  progressive 
and  retrogressive. 

Both  Wmdings  Progressive  or  Both  Retrogressive 
— The  clearest  conception  of  the  voltage  involved  may 
be  gained  by  the  use  of  diagrams,  so  reference  is  made 
at  once  to  Figs.  10  and  11,  which  show  a  25  slot  wind- 
ing, with  two  coils  per  slot,  and  one  single  coil  per 
complete  coil.  These  two  windings  are  supposed 
to  be  wound  on  the  same  core,  with  commutators  at  the 
opposite  ends.  The  four  poles  of  the  machine  are 
shown  at  the  top  of  the  figure  and  also  at 
the  bottom.  It  v.ill  be  found  by  tracing  out 
that  the  positive  brush  of  one  winding  lies  under 
the  same  pole  as  the  negative  brush  of  the  other.  In 
other  words,  B^  is  connected  to  the  positive  brush  of 
one  winding  and  T^  to  the  negative  brush  of  the  other. 
This  means,  therefore,  that  the  voltage  between  7",  and 


B..  at  that  particular  point  is  the  sum  of  the  voltage 
across  the  two  commutators  if  the  windings  are  ex- 
ternally connected  in  series,  but  if  the  windings  act  as 
two  separate  generators,  or  as  a  generator  and  motor, 
the  voltage  between  T^  and  B^  at  the  point  in  question 
would  only  be  the  voltage  across  one  commutator.  The 
voltage  between  the  other  pair  of  brushes  would,  of 
course,  be  zero  if  the  windings  are  connected  in 
series,  or  the  voltage  across  one  commutator  if  the 
windings  are  separated.  The  foregoing  will  be 
more  clearly  understood  by  referring  to  Fig.  13,  in 
which  A  is  the  winding  of  Fig.  11,  while  B  is  the 
winding  of  Fig.  10,  shown  connected  externally  in 
series.  As  an  example,  if  the  voltage  across  each 
winding  is  600,  then  the  voltage  between  -|-  a  and 
—  b  will  be  1200  volts,  and  the  coils  T^  and  B„ 
which  successively  come  in  contact  with  —  b  and 
-\-  a,  respectively,  will  have  a  potential  difference 
of  1200  volts.  The  voltage  between  —  a  and  -f-  h 
is  of  course  practically  zero.  From  the  foregoing 
it  is  evident  that  the  voltage  between  Z?,  and  Tj, 
l"ig.  12,  when  the  two  windings  are  in  series,  will 
vary  from  a  maximum,  the  value  of  which  is  twice 
the  voltage  on  one  commutator,  to  a  minimum,  the 
value  of  which  is  approximately  zero.  If  the  two 
windings  are  not  connected  in  series,  but  are  en- 
tirely separate  externally,  as  shown  in  Fig.  14, 
then  assummg  the  same  voltage  per  commuta- 
tor as  in  the  previous  example,  the  voltage  be- 
tween +  a  and  —  b  will  be  600,  and  between 
—  a  and  +  b  will  also  be  600.  In  other  words, 
-|-  o  and  -p  b  are  at  the  same  potential  above 
ground. 

One  IVinding  Progressive,  the  Other 
Retrogressive — It  will  be  found  by  tracing  out 
Figs.  9  and  10,  which  show  a  progressive  and 
retrogressive  winding  respectively,  that  the 
positive  brush  of  each ,  winding  comes  under  the 
same  pole.  This  shows,  therefore,  taking  into 
account  the  foregoing  discussion,  that  B„  and  T^ 
each  connect  to  the  positive  brush  of  their  re- 
spective windings  at  the  same  instant.  This  means, 
therefore,  that  the  voltage  between  B^  and  T^  is  the 
voltage   across   one   armature   when    the   windings   are 


FIG.    8 — FIELD    W.WE   FORM    OF   COMMUT.VTIXG   POLE   R.MLWAY    MOTOR 


connected  in  series,  as  will  be  noted  from  Fig.  13.  Or, 
using  the  same  voltage  per  winding  as  before,  the  volt- 
age between  -f-  a  and  +  6  is  600  and  between  —  o  and 
—  b  \s  also  600.  The  voltage  between  B„  and  T^  is, 
therefore,  constant  and  equal  to  the  voltage  across  one 


January,  1921 


THE  ELECTRIC  JOURNAL 


35 


winding.  If  the  windings  are  not  connected  externally 
in  series,  but  are  as  shown  in  Fig.  14,  the  vohage  be- 
tween -|-  a  and  -|-  ^  is  zero  and  between  —  a  and  —  b 
is  also  zero.  The  case  in  which  the  voltage  across  the 
two  commutators  is  unequal  will  not  be  discussed,  as 
the  voltage  relation  will  be  evident  from  the  foregoing. 


Series    Wound — If    the    main    and     commutating 
fields  in  a  series  wound  motor,  which  will  be  considered 


FIG.    9 — FULL   PITCH    PROGRESSIVE    WAVE    WINDING 
FIGS.    10   AND    II — FULL  PITCH   RETROGRESSIVE   WAVE    WINDING 
DOUBLE    COMMUTATOR    MACHINF. 

on  grounded  circuits  only,  are  connected  on  the  line 
side  of  the  armature,  then  the  voltage  to  ground  on  the 
field  coils  is  full  line  voltage,  except  for  a  few  volts 
drop  due  to  resistance  of  the  coils  themselves.  If,  on 
the  other  hand,  the  coils  are  connected  on  the  ground 
side,  they  are  normally  only  a  few  volts  above  ground. 
However,  it  has  been  found  on  railway  motors  of  the 
series  type  that  on  sudden  applications  of  voltage  the 
fields  absorb  approximately  50  percent  of  the  applied 
voltage,  which,  of  course,  means  that  some  of  the  coils 
have  a  voltage  to  ground  of  one  half  the  applied  volt- 
age. 

Compound  IVound  Ungrounded  Circuits — On  an 
ungrounded  circuit,  no  matter  on  which  side  of  the 
armature  the  series  field  coils  are  placed,  the  voltage  to 
ground  may  be  considered  as  one  half  the  generated  or 
impressed  voltage,  as  explained  for  the  general  case  of 
ungrounded  circuits.  The  shunt  coils  will  bear  the 
same  relation  to  ground  as  the  series,  and  hence  the 
middle  point  of  the  shunt-winding  may  be  considered  as 
being  normally  at  ground  potential.  This  point  is 
more  clearly  shown  by  Fig.  15.     The  voltage  between 


point  a  on  the  series  field  and  point  b  is,  for  the 
example  considered,  500  volts,  but  point  a  is  insulated 
from  ground  by  insulation  h  and  point  b  is  insulated 
from  ground  by  insulation  k.  The  condition 
may,  therefore,  be  illustrated  by  Fig.  16,  in 
which  a  familiar  problem  in  electrostatics  will  be 
recognized.  Without  going  into  the  theor}',  which  is 
discussed  in  most  text  books  on  the  subject,  it  is  suffi- 
cient to  say  that  the  potential  gradient,  or  volts  per  mil 
in  the  insulation,  will  distribute  inversely  as  the  specific 
inductive  capacity  of  the  insulating  material. 
This  means  that  if  insulation  h  and  k  are  of 
the  same  material  and  of  the  same  thickness, 
the  voltage  to  ground  at  points  a  and  b  will 
be  one-half  the  applied  voltage.  Referring 
again  to  Fig.  15,  the  voltage  between  point  / 
on  the  shunt  field,  and  point  d  on  the  shunt 
I  field  is  500  volts,  and  the  voltage  to  ground, 
of  points  /  and  d  from  analogy  to  the  explana- 
tion given  for  the  series  field,  will  be  one-half 
the  applied  voltage.  As  there  is  a  uniform 
'  voltage  drop  through  the  shunt  field,  the  dif- 
ference of  potential  between  e  and  /  or  be- 
tween d  and  c  will  be  one-half  the  applied 
voltage.  This  gives,  therefore,  assuming 
again  uniform  material  and  thickness  of  insu- 
lation g,  zero  voltage  to  ground  at  point  c. 
The  voltage  to  ground  on  a  shunt  w-inding, 
therefore,  varies  from  a  maximum  of  one-half 

/rry-T-T-! 


FIG.    13 — ARR.\NGEMEXT  OF  COILS   IN    SLOT 
OF    DOUBLE    WINDING    MACHINE 


applied  voltage  down  to  zero. 

Voltage  Between  Shunt  and  Series  Coils — From 
Fig.  15,  point  a  on  the  series  and  point  /  on  the  shunt 
field  are  obviously  at  the  same  potential,  but  the  volt- 
age between  point  c  on  the  series  and  point  d  on  the 
shunt   is  the  applied  voltage  less  the  IR  drop  in   the 


FIG.     1.3 — SERIES 

CONNECTION     FOR     DOUBLE 

WINDING     MACHINE 


FIG.     14 — PARALLEL 

CONNECTION     FOR     DOUBLE 

WINDING    MACHINE 


series  field  which,  in  most  cases,  is  a  very  small  per- 
centage of  the  whole.  Therefore,  for  practical  con- 
siderations, the  voltage  between  the  shunt  and  series 
windings  varies  uniformly  from  zero  to  approximately 
full  applied  voltage. 


36 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


Voltage  Between  Layers  of  Series  Coils — If  the 
series  coils  are  wound  in  two  or  i.iire  layers,  as  is  the 
case  with  the  majority  of  railway  motor  field  coils,  the 
maximum  possible  voltage  between  layers  under 
normal  conditions  will  be  the  77?  drop  in  the  coil.     Un- 


1 


m 


I 


FIG.    15 — COMPOUND-WorXD    MACHINE    UNGROITNOED 

der  sudden  changes  in  load  or  application  of  voltage 
this  voltage  may  be  much  higher,  and  may  reach 
a  point  such  that  the  fields  absorb  fully  one-half  the 
applied  voltage,  in  which  case  the  maximum  voltage  be- 
tween layers  could  be  expressed  by  the  following 
formula : — 

Ft 

^'=  cynr (3) 

Where, — 

Vi  =  volts  between  laj'ers. 

Ft  =:  total  volts  absorbed  by  series  field. 

C    =  No.  of  coils. 

L    =^  No.  of  layers  per  coil. 

The  above  formula  is  general  and  applies  under 
all  conditions.  If  the  field  coils  are  connected  ex- 
ternally in  series,  the  maximum  possible  voltage  be- 
tween layers  will  then  be  much  higher  than  is  the  case 
if  the  layers  of  each  coil  are  connected  in  series.  Fig. 
17  shows  four  two-layer  fields  connected  internally  in 


FIG.     16 — SIMPLIFIED    DIAGRAM    OF    VOLTAGE    RELATIONS    BETWEEN 
LIVE    PARTS    OF    AN    UMCROUNDED    M.ACHINE 

series.  Fig.  18  shows  the  same  field  connected  ex- 
ternally in  series  in  one  way  and  Fig.  19  with  a  diflfer- 
ent  external  connection.  The  voltage  between  the 
layers  of  all  coils  connected  as  in  Fig.  17  will  be  the 
same  as  explained  before,  and  is  given  by  formula  (3). 
The  voltage  between  layers  of  coil  /  in  Fig.  18  will  be. 


of  course,  the  full  absorbed  voltage  of  the  field  which, 
as  before  stated,  may,  at  times,  be  as  high  as  one-half 
the  applied  voltage.  The  voltage  between  layers  of  coil 
2  will  be  three  quarters  of  the  voltage,  of  coil  j  one- 
half,  and  of  coil  4  one-quarter.  This  applies  only  to 
a  four-pole  motor  or  generator,  but  the  voltage  rela- 
tion will  be  the  same  for  any  number  of  coils.  The 
voltage  between  layers  of  coils  when  connected  as 
shown  in  Fig.  19  will  be  less  than  the  maximum  of  Fig. 
18,  and  will  be  equal  for  all  coils.  The  value  will  be 
one-half  the  absorbed  voltage  of  the  field.  The  connec- 
tions shown  in  Figs.  18  and  19  are  used  in  field  control 
railway  motors. 

Voltage  Between  Turns— The  volts  between  turns 
for  any  field,  series,  compound  or  shunt,  is  the  voltage 
absorbed  by  the  field,  divided  by  the  number  of  turns 
in  series.  If  the  shunt  coil  is  wound  in  definite  turns 
and  layers,  the  highest  voltage  between  any  two  given 
wires  would  be  the  voltage  between  layers,  but  if  the 


FIG.     17 — COIL 

LAYERS 

INTERNALLY 

CONNECTED    IN 

SERIES 


FIG.    18 — COIL 

LAYERS 

EXTERNALLY 

CONNECTED    IN 

SERIES 


FIG.    19 — COIL 

LAYERS 

EXTERNALLY 

CONNECTED    IN 

SERIES 


coil  is  wound  hit  or  miss,  then  the  voltage  between  any 
two  wires  might  be  much  higher  than  if  it  were  wound 
in  definite  layers. 

Voltage  Between  Main  and  Comnmtating  Coils — 
The  commutating  coils  are  always  on  a  different  pole 
from  the  shunt  or  series  coil,  and  so  ordinarily  there  is 
no  difficulty  involved  in  insulating  between  them,  but 
it  is  well  to  recognize  that  the  voltage  in  some  cases 
may  be  quite  high.  For  example,  if  the  series  and 
commutating  coils  are  connected  on  different  sides  of 
the  armature,  the  voltage  between  them  will  be  ap- 
proximately full  applied  voltage.  Or,  an  arrangement 
involving  higher  voltage  still  would  be  where  a  num- 
ber of  motors  are  connected  in  series,  as  on  the  3000 
volt  direct-current  railway  system,  with  the  fields  on 
the  ground  side  and  a  portion  of  the  commutating  coils 
on  the  line  side  or  separated  from  the  line  by  the  ab- 
sorbed voltage  of  only  one  motor. 


t;UY  F.  SCOTT 


'O 


IN  MOTOR  applications,  such   as   for  rolling  mills 
and   hoists,   where   the   loads   are   intermittent  and 
variable,    high    current    peaks    are    produced    by 
sudden  application  of  load  at  the  start  of  each  opera- 
tion.    These  high  peaks  are  objectionable  for  the  fol- 
lowing reasons: — 

I— They  affect  the  voltage  regulation  on  the  lines. 
-^—When  power  is  purchased  on  a  maximum  dcmaml 
these  peaks  result  in  increased  costs. 


basis 


FIG.     I— .VUTO.M.'^TIC    LIQUID' SI-IP    REGUL.\TOR 

3— There  is  difficulty  in  obtaining  reasonable  overload 
protection  for  the  motor. 

4 — Heavy  strains  are  introduced  in  windings  and  me- 
chanical parts  of  the  motor. 

These  peaks  may  be  materially  reduced  by  the  addi- 
tion of  a  flywheel  on  the  motor  shaft  and  a  means  of 
utilizing  the  stored  energy  of  this  flywheel  when  peak 
loads  occur.  This  is  accomplished  with  induc- 
tion motors  by  increasing  the  slip  of  the  motor 
at  these  periods  through  the  introduction  of  re- 
sistance in  the  secondary  circuits.  This  resist- 
ance may  be  in  the  circuit  permanently  or  intro- 
duced by  automatic  slip  regulators.  The  best 
known  types  cf  slip  regulators  are  the  magnetic 
contactor  type  with  "notch  back"  relays,  and  the 
liquid  type. 

The  liquid  slip  regulator,  shown  in  Figs,  i 
and  2,  consists  of  a  tank,  to  the  bottom  of  which 
are  attached  three  insulated  cells,  each  contain- 
ing a  stationary  electrode.  The  tank  and  cells 
are  filled  with  an  electrolyte  (a  solution 
of  Na,  CO3)  which  is  obtained  commercially  as 
soda  ash.  The  required  density  of  this  solu- 
tion depends  largely  upon  the  characteristics  of  the  in- 


dividual motor  and  upon  load  condition  during  the 
starting  period.  For  these  reasons  no  definite  density 
can  be  recommended,  but  in  most  cases  the  solution 
density  giving  best  results  is  between  one  and  two  per- 
cent by  weight.  The  operating  temperature  of  the  elec- 
trolyte should  not  exceed  80  degrees  C,  and  in  order  to 
keep  It  within  this  limit,  a  set  of  coils  is  mounted  in  the 
tank  through  which  cooling  water  is  circulated. 

Above  each  stationary  electrode  is  suspended  a 
movable  electrode.  These  three  movable  electrodes  are 
connected  mechanically  and  electrically,  and  are  sus- 
pended from  balance  arms  which  are  attached  to  the 
shaft  of  a  torque  motor,  mounted  above  the  main  tank. 
Adjustable  counterweights  are  suspended  from  the 
outer  ends  of  the  balance  arms.  The  primary  circuit 
of  the  torque  motor  is  supplied  with  energ>'  from  the 
secondary  of  a  series  transformer  connected  in  the 
main  circuit,  as  shown  in  Fig.  3,  while  the  secondarv 
receives  constant  excitation,  so  that  the  torque  is  pro- 
portional to  the  primary  current. 

The  connections  are  such  that  the  torque  motor 
tends  to  rotate  in  the  direction  to  separate  the  elec- 
trodes, and  thereby  introduce  resistance  into  the  motor 
circuit.  As  the  current  in  the  torque  motor  varies  in 
a  direct  ratio  and  simultaneously  with  the  current  in  the 
main  motor,  by  the  adjustment  of  countenveights  and 
by  changing  the  transformer  ratio,  the  current  at  which 
the  torque  motor  separates  the  electrodes  may  be  fixed 
at  any  desired  value. 

The  effects  of  the  introduction  of  a  slip  regulator 
in  the  motor  circuit  are  shown  in  Fig.  4.  This  is  a 
typical  recording  wattmeter  curve.  The  peaks  taken 
by  the  motor  when  the  regulator  was  not  operating 
varied  between  800  and  1200  kw,  while  with  the  slip 
regulator  in  service  the  peaks  were  reduced  to  a  maxi- 


CRCSS-SKCTION     OF     LIOIID    .SLIP    REGL'L.ATdK 


mum  of  less  than  800  kw,  with  an  average  of  about  500 
kw. 

The  liquid   type   .slip   regulator   and   the   contactor 


38 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


type  function  to  produce  the  same  effect.  There  is, 
however,  the  difference  that,  in  the  Hquid  type,  the  re- 
sistance  change   is   gradual,   whereas   in  the   contactor 

/S  S/>un/  Trons/br/ners. 


I  y  Secoraary  ffesistance. 


sufficient  size  to  contain  all  the  electrolyte.  Facilities 
.■should  be  provided  for  either  pumping  this  electrolyte 
hack  into  the  tank,  or  discharging  it  into  the  sewer. 
With  these  facilities  the  tank  can  be  emptied, 
the  electrodes  inspected  and  cleaned,  and  the 
electrolyte  returned  to  the  tank,  in  a  very 
short  time.  When  this  is  done,  it  is  advisable 
to  leave  an  inch  or  two  of  the  electrolyte  in 
the  pit,  to  be  drained  into  the  sewer  together 
with  any   sediment  that   may   have   collected. 


,3 kEGlLATDK   ION  NKCTEll    TX    MclTIIK 


\\  This  Secona Set    This  small   loss   of   electrolyte   should   be   re- 
.-v-i  Hesisiors'/s'      placed,  and  the  proper  level  maintained  by  the 
rorlvaSSUp       addition  of  water  through  a  valve  provided  in 
the    cooling    coils,    and    by    the    addition    of 


W/""''*    Regu/ofors. 

SECONDARY 


type  the  changes  are  in  abrupt  steps,  the  number  of 
which  are  limited.  This  difference  is  plainly  shown  in 
Fig.  5.  Further,  in  the  liquid  type,  the  change  in  re- 
sistance follows  the  load  closely;  whereas,  in  the  con- 
tactor type  the  peak  current  must  be  present  before  the 
relays  can  function.  There  is  also  a  slight  time  lag 
due  to  the  inertia  of  moving  parts  of  the  controllers. 
Again,  these  relays  must  be  so  designed  that  the  resist- 
ance steps  will  be  inserted  at  a  high 
value  of  current  and  cut  out  again 
at  a  comparatively  low  value,  so 
that  the  current  rush  caused  by  the 
short-circuiting  of  the  resistance 
step  will  not  be  sufficiently  high  to 
cause  the  relay  again  to  insert  the 
•resistance,  for  this  would  result  in 
a  short  life  of  contacts  due  to  suc- 
cessive opening  and  closing.  This 
peculiarity  of  design  in  the  relays 
results  in  the  resistance  being 
in  the  circuit  longer,  and  con- 
sequently this  type  of  regulator  is 
less  efficient  than  the  liquid  type. 
Another  thing  to  be  considered  is 
the  space  requirement.  The  liquid 
type  regulator,  being  water  cooled 
vvill  occupy  considerably  less  space 
than  types  which  use  metallic  re- 
sistance. 

In   operating,    the   liquid    type 
slip    regulator,    after   having   been   ' 
adjusted  for  the  load  requirements 
by  making  the  proper  transformer 
connections   and  by   the   finer   ad- 
justment with   the   counterweights, 
requires  little  attention  other  than 
an  occasional  inspection  of  electrodes  and  the  cleaning 
of  the  tank  and  cooling  coils.     This  has  in  some  cases 
resulted  in  a  tendency  toward  neglect  of  the  apparatus, 
which  should  be  carefully  avoided. 

For  cleaning  and  inspection,  it  is  advisable  to  have 
a  pit,  with  sewer  connections,  beneath  the  regulator,  of 


sodium  carbonate  to  restore  its  density. 

The  cooling  coils  can  be  kept  free  fi'om  scale  by 
blowing  compressed  lir  through  them  frequently.  For 
this  purpose  it  is  well  to  have  a  permanent  air  connec- 
tion at  the  inlet  end  ol"  the  coils. 

During  the  cou'\se  of  development  of  the  liquid  slip 
regulator,  covering  a  number  of  years,  experiments 
were  made  with  electrode  cells  of  various  grades  of 
earthen-ware.     Because  of  a  slow  disintegration  of  the 


4 — WATTMETER    RECORDS    OF    60O    HI".     MOTOR    DRIVIN(;  A    BIU.ET    MILL 

The  top  record  was  made  without  the  regulator.  .\ 
comparison  with  the  bottom  record  shows  the  effect  of  in- 
troducing  a   slip   regulator  into   the   motor   circuit. 


roMpARISON    OF    LOAD    CONDITTONS    OF    A     ISOO    HP.     SHEET     MILL    .MOTOR 

earthen-ware  under  the  action  of  the  hot  soda  solutions, 
and  the  effects  of  the  sudden  variations  in  temperature, 
the  results  with  these  cells  have  not  been  verj'  satisfac 
torj^  and  their  use  has  been  discontinued.  Specially 
constructed  cells  of  treated  wood  suspended  by  in- 
sulated hangers  are  now  being  used,  with  good  results. 


On  cli; 


E.  SEARS 

Divii^ion  Master  Mechanic 


^nul  Rnilroai] 


N  ELECTRIFYING  a  railroad  through  the  Rocky 
Mountains,  and  more  especially  through  the  Cas- 
cade Mountains  in  the  northern  states,  the  weather 
conditions  must  be  carefully  considered,  as  the  tempera- 
ture sometimes  stays  around  forty  to  fifty  degrees  below- 
zero  for  days  at  a  stretch.  Seasonal  snow  falls  of 
thirty  to  forty  feet  are  recorded  in  places  by  the 
weather  bureau.  A  snow  storm  of  only  a  few  inches  on 
the  level  may  drift  to  many  feet  deep  in  some  places, 
and  cuts  are  sometimes  completely  failed  with  snow 
within  half  an  hour  after  they  have  been  opened  by 
the  rotary  snow  plows.  With  steam  locomotives,  such 
weather  conditions  are  at  times  very  serious,  resulting 
in  temporary  suspension  of  service,  particularly  freight, 
on  account  of  the  reduction  of  steaming  capacity  or  the 
freezing  up  of  the  locomotives.  The  severe  cold  does 
not,  of  cour.se,  impair  the  operation  of  an  electric  loco- 


FK;.    I — ROT.\RY    SNOW    PLOW 

motive,  but  is  to  some  extent  beneficial.  It  has,  more- 
over, been  found  in  actual  operation  on  the  Chicago, 
Milwaukee  &  St.  Paul  Railroad  that  the  heavy  snow 
falls  do  not  interfere  with  the  electric  trains  nearly  as 
much  as  with  the  steam  trains,  and  that  clearing  the 
tracks  of  snow  is  easier  with  electric  locomotives  than 
with  the  steam  locomotives. 

A  moderate  depth  of  snow,  say  four  to  five  feet, 
unless  it  is  heavily  packed,  and  even  greater  depths  ex- 
tending for  only  a  short  distance,  can  be  removed  most 
easily  by  means  of  the  wedge  type  snow  plow.  The 
Chicago,  Milwaukee  &  St.  Paul  Railroad  have  a  num- 
ber of  double  mold  board  Barr  plows  of  this  type  whicli 
are  placed  ahead  of  loaded  ballast  cars  and  driven  at 
high  speed  through  the  snow  by  two  or  three  locomo- 
tives. These  are  usually  able  to  take  care  of  the  snow 
situation  in  the  Rocky  Mountains,  as  the  snow  does  not 
usuall  •  attain  as  great  depth  in  this  territory  as  in  the 


coastal  ranges.  When  fighting  snow  in  this  manner  the 
entire  crew  are  continually  wet  from  the  snow  which 
is  melted  by  the  heat  of  the  locomotives.  The  flying 
snow  fills  every  part  of  the  equipment,  and  the  quanti- 


1  .11)  -^-   'Hi;  ■ 


■■"""''11 


T", 


FIG.    2 — ROTARY    SNOW    PLOW    PUSHED   nv    STE.\M    LOCO.MOTIVE 

ties  of  snow  which  are  necessarily  shoveled  into  the  fire 
box  with  the  coal  makes  steaming  difficult.  A  con- 
siderable gang  of  laborers  with  snow  shovels  is  usually 
carried  for  use  in  emergencies. 

For  deeper  snows  the  Chicago,  Milwaukee  &  St. 
Patil  Railroad  have  six  rotary  snow  plows,  which  are 
used  mostly  in  the  Bitter  Root  and  Cascade  Mountain 
ranges.  As  will  be  evident  from  Fig.  i  the  rotary  snow 
plow  is  pushed  ahead  of  the  locomotive,  and  acts  as  a 
large  auger,  boring  its  way  through  the  snow  banks. 
The  rotary  wheel  is  about  I2  feet  in  diameter.  It  is 
faced  with  knives  that  cut  into  the  snow  which  is 
thrown  by  centrifugal  force  out  of  the  chute  at  the 
upper  part  of  the  wheel  housing.     The  wheel  can  be 


FIG.    3 — ROTARY    SNOW    PLOW   AT   ROLAND,    IDAHO 
IN    THF.    BITTER    ROOT    MOUNTAINS 

driven  in  either  direction  in  order  to  throw  the  snow  to 
whichever  side  of  the  track  is  desired.  The  blades  are 
tied  together  in  pairs,  and  when  the  direction  of  rota- 
tion   is    reversed,    the    centrifugal    action    reverses    the 


40 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


blades,  so  that  they  always  cut  in  the  direction  of  the 
rotation.  They  are  strong  enough  to  handle  slides  con- 
taining small  tree  stumps  without  sustaining  any  ma- 
terial damage. 

The  plow  is  equipped  with  a  boiler  and  an  engine 
which  drives  the  rotary  wheel.  This  engine  and  boiler 
are  operated  by  an  engineer  and  fireman  in  the  cab  of 
the  snow  plow. 

The  snow  in  ttie  Bitter  Root  and  Cascade  Moun- 
tains often  attains  a  depth  of  15  to  20  feet  in  one  snow 
storm,  and  there  are  times  when  these  drifts  are  higher 
than  the  plow  itself.  The  rotarj'  plow  can  operate  in 
drifts  which  are  somewhat  deeper  than  the  plow  itself, 
as  the  snow  is  thrown  out  with  considerable  force. 
When  the  snow  is  p.-^.cked  deeper  than  the  rotaries  can 
handle,  short  holes  are  bored  into  it  with  the  rotary 
wheel,  into  which  the  tops  or  sides  are  broken  by 
laborers. 

The  snow  slides  are  the  greatest  enemy  of  the  snow 
plow  in  the  mountain  district,  as  they  cover  the  tracks 
to  considerable  depths ;  at  times  they  catch  a  plow  and 
bury  it  completely.  Several  times  the  entire  crew  have 
been  caught  in  such  slides,  making  it  very  difficult  for 
them  to  dig  their  way  out.  In  one  case,  one  of  the 
electric  locomotives  without  a  rotary  plow  attached,  ran 
into  a  large  drift  and  several  visiting  electrical  engi- 
neers who  were  on  the  locomotive  were  entirely  buried 
in  the  snow,  which  forced  itself  through  the  broken 
windows  and  filled  the  cab. 

Prior  to  the  electrification,  as  high  as  three  or  four 
steam  freight  locomotives  were  placed  behind  the 
rotary  plow.  Now  the  rotaries  are  handled  by  one  elec- 
tric locomotive  and,  inasmuch  as  each  half  of  the  pres- 
ent freight  locomotives,  when  not  coupled  together,  can 
be  run  as  a  separate  unit,  only  one  unit  of  the  engine  is 
sometimes  employed,  although  in  heavier  drifts  both 
units  can  be  cut  in,  g.ving  full  power  to  push  the  snow 
plow.  The  tractive  effort  required  to  push  the  rotaries 
depends  on  the  depth  jf  the  snow,  and  we  have  had  no 
deep  snows  recently.  Last  winter  we  had  no  use  for 
the  rotaries  at  all. 

The  heavy  snow  falls  do  not  interfere  with  the 
electrical    operation    (iver    the    mountain    territory'    as 


much  as  they  did  with  steam,  since  an  electric  engine 
will  plow  through  snow  where  a  steam  engine  will  not 
go.  The  heavy  snows  have  no  bad  effect  on  the  over- 
head wiring.  We  are  not  subject  to  any  heavy  sleet 
storms  in  this  section,  but  at  times  a  very  heavy  frost 
collects  on  the  two  4/0  copper  trolley  wires.  With  a 
pantagraph  of  the  double  shoe  type,  sliding  on  two 
trolleys  whose  hangers  are  spaced  alternately,  excel- 
lent current  collection  is  obtained  at  all  times  and  sleet 
and  frost  have  not  so  far  bothered  us  to  any  extent. 
Sometimes  during  heavy  frosts,  both  pantagraphs  are 
raised,  the  front  one  serving  principally  to  clear  the 
wires. 

Experience  indicates  that  snow  fighting  can  be 
handled  better  with  electrical  equipment  than  with 
steam.  The  electrical  equipment  gives  better  speed 
control,  as  there  is  no  difficulty  in  securing  all  the  power 
desired  and  there  is  no  opportunity  for  the  freezing  up 
of  injector  pipes,  etc.,  on  the  locomotive,  or  the  neces- 
sity of  having  to  go  back  for  water  or  fuel,  except  to 
meet  the  fuel  and  water  demands  of  the  rotary  plow 
itself. 

The  only  change  necessary  to  adapt  the  rotary 
snow  plow  to  use  in  the  electrified  territory  was  the 
attaching  of  a  deflector  on  the  upper  part  of  the  rotary 
hood,  so  that  the  snow  and  other  material,  when 
thrown  out,  would  not  come  in  contact  with  the  power 
limiting  and  other  wires.  These  are  at  such  a  height 
that  a  rotary,  in  its  original  condition,  would  throw  the 
snow  onto  the  wires  and  trouble  was  experienced  from 
this  cause  when  first  operating  the  rotaries  in  the  elec- 
trified section. 

No  doubt  in  the  rjcar  future  rotary  snow  plows  will 
he  built  with  electric  motors  instead  of  steam  engines 
for  electrified  territory,  and  the  old  ones  will  be 
changed  over  for  electric  operation.  The  only  draw 
back  to  operating  the  plow  itself  with  motors  is  that 
quite  often  the  rotary  wheel  will  freeze,  in  which  case 
it  is  necessar)'  to  have  steam  available  to  thaw  it  out. 
This  could  be  overcome  by  using  a  small  boiler  similar 
to  the  ones  which  are  now  being  used  for  heating  the 
passenger  trains. 


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To  the  Editor  of  The  Eiiciric  Joiinial: 

Dear  Sir:— The  article  on  the  Erie  Railroad  Electrification, 
published  in  the  October  aumber  of  The  Electric  Journal,  is  an 
excellent  account  of  th<  pioneer  single-phase  steam  railroad 
electrification  in  commercial  service  in  the  United  States,  and 
is  naturally  of  especial  i-iterest  to  the  present  writer,  because 
of  his  connection  with  il  in  the  capacity  of  engineer-in-chargo 
of  the  design  and  execution  of  the  work  which  was  carried  out 
between  September  lfX)6,  and  June  1007,  by  the  old  engineerinR 
organization  of  Westinghouse,  Church,  Kerr  &  Company,  which 
left  its  stamp  upon  so  many  large  railway  improvements 
throughout  the  countr>-. 


Mr.  Hershcy  is  not  quite  correct  in  stating  that  the  New- 
York,  New  Haven  &  Hartford,  and  the  Boston  &  Maine  smgle- 
phase  electrifications  were  in  successful  opcraUon  at  the  Ume 
the  Erie  electrification  was  created.  It  is  true  that  the  former 
electrification  had  been  in  process  of  construction  for  a  year 
or  two  and  the  engineering  features  of  it  naturally  supplied 
some  useful  precedents  in  working  out  the  details  of  the_  over- 
head construction  on  the  Erie  road,  but  the  difference  in  the 
size  of  the  jobs  was  so  great  that  less  than  a  year  suihced  to 
do  the  preliminar%'  engineering  and  installation  for  the  Erie, 
and  its  successful  and  continuous  commercial  operation  bega-.i 
on  or  about  June  23,  1007,  just  about  one  week  beforr  regular 


January,   192 1 


THE  ELECTRIC  JOURNAL 


41 


operation  began  on  the  New  Haven.  Therefore,  it  can  jnst'y 
be  claimed  that  the  Erie  electrification  was  the  first  ll  000-volt, 
single-phase  system  to  get  into  regular  commercial  operation 
on  a  steam  ranroad.  1  he  i.oosac  tunnel  eiecinricauon  01 
the  Boston  &  Maine  Railroad  was  not  constructed  until  1910. 

Credit  for  the  original  suggestion  of  single-phase  opera- 
tion for  the  Erie,'  may  be  due  to  Mr.  L.  B.  Stillwell  and  his 
organization,  by  whom,  if  the  writer  remembers  correctly,  this 
system  was  recommended  to  the  management  of  the  Erie  rail- 
road; but  the  contract  for  construction  and  equipment  was 
placed  with  Westinghouse,  Church,  Kerr  &  Company.  It  is 
evident  from  Mr.  Hershey's  article  that  all  the  component  parts 
of  the  original  installation  are  still  in  service,  with  the  addition 
of  two  motor  cars  and  the  supplementary  steel  trolley  wire.  In 
the  summer  of  IQ06,  electric  service  of  si.x-car  trains  was  not 
contemplated  as  a  regular  feature  of  operation,  but  the  fact 
that  it  is  possible  with  two  motor  cars  and  four  trailers  is  due 
to  the  careful  analysis  of  the  proposed  electric  service  made  at 
that  time. 

There  were  not  more  than  five  or  six  regular  railway  sta- 
tion stops  in  the  19  miles  between  Rochester  and  Av  n  ;  but  in 
order  to  attract  travel,  the  railway  company  specific-  ;'iat  pro- 
vision should  be  made  for  local  stops  by  most  of  the  .rains,  it 
every  cross-road  along  the  route.  The  carrying  out  of  this 
provision  is  undoubtedly  one  of  the  factors  that  has  made  tlii' 
electrification  so  popular  with  the  public  that  it  serves,  and  was 
the  immediate  cause  of  the  100  percent  increase  in  its  trafHc 
during  the  first  year  of  its  operation.  These  cross-roads  stops 
average  about  one  mile  apart  and,  as  it  was  expected  that  the 
railroad  trains  would  very-  frequently  consist  of  one  motor  car 
and  one  trailer  and  it  was  judged  that  on  frequent  occasions 
such  a  train  would  be  required  to  make  all  stops  over  the  line, 
an  equipment  of  four  100  hp  motors  was  found  necessary  in 
order  to  be  sure  that  the  motors  should  at  all  times  be  equal  to 
the  most  severe  duty,  with  the  50-50  proportion  of  motor  cars 
and  trainers  contemplated.  It  was  also  found  that  uiih  the  four- 
motor  equipment,  two  trailers  per  motor  car  could  be  put  on 
express  runs  with  fewer  stops.  We  thus  discounted  in  advance 
the  inevitable  tendency  of  steam  railroad  men  to  load  equipment 
to  its  limit  as  a  matter  of  regular  operation,  by  stating  these 
limitations  clearly  and  providing  equipment  that  would  always 
meet  them;  and  the  wisdom  of  an  equipment  of  four  too  hp 
motors  per  motor  car,  as  a  matter  of  engineering  foresight,  has 
been  demonstrated  continuously  from  the  very  beginning,  as  is 
still  attested  by  the  review  of  operating  records  given  by  Mr. 
Hershey.  The  average  figure  of  79  watthours  per  ton-mile 
does  not  seem  too  large  when  it  is  recalled  that  this  is  a  sub- 
urban rapid  transit  service  with  relatively  frequent  stops,  quite 
different  from  a  through  service  with  long  runs.  The  multiple- 
unit  control,  the  pantograph  trolley  and  all  other  auxiliary- 
features  of  the  equipment,  functioned  very  well  from  the  very 
beginning,  and  it  would  appear  from  the  records  that  all  parts 
of  the  car  equipment  are  as  satisfactory  at  this  date  as  they 
were  13  years  ago. 

In  view  of  this  record,  in  an  art  which  is  supposed  to  be 
constantly  improving  and  rendering  obsolete  the  work  of  five 
or  ten  years  previous,  it  would  be  interesting  to  get  comments 
from  professional  valuation  engineers  as  to  the  percentage  of 
obsolescence  that  should  be  applied  to  this  equipment,  in  com- 
puting its  present  day  value. 

The  overhead  trolley  construction  was  the  one  tough  prob- 
lem in  this  electrification.  Mr.  Hershey  is  not  quite  correct 
when  he  says  "At  the  time  this  installation  was  made,  overhead 
construction  was  still  somewhat  in  the  preliminary  stage;" 
though  his  qualification  immediately  following,  that  the  catenary 
type  of  suspension  was  at  that  time  experimental,  is  quite 
correct.  For  the  benefit  of  the  present  generation  of  electric 
railway  engineers,  let  it  be  stated  that  overhead  trolley  con- 
struction in  general  is  not  materially  different  from  what  it 
was  25  years  ago,  by  which  time  the  principles  and  the  me- 
chanical parts  used,  had  pretty  well  settled  down  to  their 
present  standard  forms.  But  in  igo6  the  catenary  form  of 
construction  was  only  one  or  two  years  old,  and  most  of  the 
engineers  who  had  to  tackle  it  at  that  time  had  to  set  their  own 
precedents,  the  Erie  installation  forming  no  exception. 

In  designing,  purchasing  and  erecting  the  overhead  equip- 
ment, mechanical  ruggedness  was  kept  constantly  in  view  as  the 
prime  requisite,  and  the  rigid  fastenings  between  messenger  and 
trolley  wire  were  designed  accordingly.  It  is  quite  true  that, 
in  the  original  installation,  we  had  to  take  some  chances  with 
the  effects  of  the  differences  of  expansion  and  contraction  be- 
tween the  steel  messenger  and  copper  trolley  wire.  These 
differences  were  somewhat  accentuated  by  the  fact  that  there 
is  very  little  curvature  in  the  railway  line  and  that  curvature 


is  very  gentle,  so  that  there  is  less  chance  for  the  elasticity  of 
the  poles  to  let  the  wires  come  and  go  cross-ways  of  the  track 
at  curves,  and  thus  case  off  the  longitudinal  temperature 
stresses,  as  is  the  case  on  a  crooked  line. 

During  the  early  operation  period  it  was  necessary  to  pull 
the  trolley  wire  considerably  tighter  than  would  have  been  the 
case  had  there  been  more  frequent  ovcriapping  breaks  in  the 
trolley  wire,  or  more  curvature  in  the  line.  It  is  possible  that 
a  less  rigid  hanger  rod  between  messenger  and  trolley  would 
have  eased  the  situation  somewhat,  but  at  that  time  we  did  not 
like  to  risk  any  element  of  flexibility  that  might  cause  wear  on 
the  galvanizing  of  the  messenger  cable.  Looking  back  on  the 
ruggedness  of  the  methods  then  used,  the  writer  confesses  his 
apprehensions,  at  the  time,  of  a  great  deal  more  trouble  than 
ever  happened.  As  it  turned  out  the  rigid,  rugged  type  seems 
to  have  done  pretty  well  for  the  traffic  conditions  prevailing  on 
the  Erie,  for  it  was  seven  or  eight  years  before  it  was  found 
necessary  to  add  the  supplemental  trolley  wire.  It  should  also 
be  stated  in  this  connection  that  the  pressure  for  rapid  com- 
pletion of  this  contract  was  very  insistent,  because  of  the 
necessity  for  promptly  heading  off  threatened  competition  from 
a  cross-country  trolley  line  that  was  then  being  promoted 
through  the  same  region;  and  there  was  no  time  for  experi- 
ments, or  for  the  developing  of  refinements  that  were  subse- 
quently found  possible  on  work  of  this  character,  such  as  were 
incorporated  a  year  or  two  later  on  similar  jobs. 

T-hf  ov.— head  work  was  insulated  throughout  with  porce- 
lain, as  r\^  .!■;,.  jm,-  i;  i'  insulating  compounds  had  then  been 
perfected  vvhicn  ■,\...i:'c  stand  11  000  volts  in  all  kinds  of 
weather.  We  tried  one  such  compound  for  strain  insulators, 
and  for  suspensions  for  use  over  yard  tracks,  but  its  failure 
was  so  prompt  and  so  universal  that  we  abandoned  it,  and  sub- 
stituted porcelain  everywhere. 

The  tension  rods  for  the  trolley  bracket  arms  were  so  at- 
tached to  the  pole  as  not  to  require  boring  of  the  pole  near  the 
top,  in  order  to  prevent  access  of  moisture  into  the  pole  top, 
thereby  lengthening  its  life.  This  refinement  may  have  been 
considered  expensive  at  the  time,  but  the  excellent  record  of 
durability  shown  by  the  chestnut  poles  has  probably  been 
assisted  somewhat  by  attention  to  this  detail.  The  catenary 
construction  in  terminal  yards  is  supported  by  spans  carried  on 
steel  poles  of  the  tripartite  type,  designed  stiff  enough  to  require 
no  back  guying. 

This  system  was  erected  and  placed  in  operation  at  a  time 
when  the  so-called  "battle  of  systems"  was  raging  most  fiercely. 
Being  a  single  track  affair  on  a  subsidiary  division  and  not  in 
any  way  conspicuous,  the  Eric  electrification  has  been  plugging 
along  for  13  years  without  arousing  much  widespread  interest, 
although  from  the  very  start  its  operating  success  was  such, 
both  from  the  standpoint  of  reliability  in  public  service  and  in 
meeting  financial  expectations,  that  the  railway  officials  used  to 
express  the  wish  that  the  whole  division  were  electrified  instead 
of  only  a  small  part  of  it.  The  electric  motor  cars  were  used 
to  pull  derailed  steam  locomotives  on  to  the  track,  even  in  the 
earliest  years  of  electrification,  and  probably  do  it  yet  upon 
occasion.  The  writer  was  once  told  of  the  indignant  refusal 
of  the  railway  company  to  listen  to  a  proposal  from  an  outside 
source,  that  the  single-phase  system  be  replaced  by  a  high- 
tension  direct-current  system. 

Unquestionably  the  continued  operating  success  of  this 
system  is  largely  due  to  the  faithful  and  intelligent  supervision 
it  has  had  from  Mr.  Thurston,  who  has  been  connected  with 
the  system  since  its  installation ;  and  to  the  co-operation  which 
he  has  effected  between  two  sets  of  employees  trained  re- 
spectively in  the  schools  of  steam  and  electricity. 

A  complete  description  of  the  Eric  installation  was  pre- 
pared by  the  writer  and  published  with  illustrations  in  the 
"Electric  Railway  Journal"  during  October,  1007,  giving  con- 
siderable detail  with  regard  to  the  features  of  the  car  equip- 
ment, trolley  construction,  car  house  and  substation.  Mr. 
Hershey's  article,  written  thirteen  years  later,  is  a  sufficient 
answer  to  the  past  and  present  criticisms  of  the  efficiency  of  the 
single-phase  system  under  conditions  similar  to  those  nb'.'i'ncd 
on  the  Rochester  division  of  the  Erie  Railroad,  which  is  a 
typical  single-track  line  of  physical  characteristics  identical 
with  many  of  the  steam  railroad  trunk  lines  of  the  country. 
It  is  also  an  object  lesson  in  railroad  economics,  as  an  example 
of  the  wisdom  of  the  Erie  management  in  preventing  a  waste 
of  new  capital  in  a  competitive  road,  by  seizing  the  opportunities 
of  electric  motive  power,  in  order  to  increase  the  capacity  and 
usefulness  of  an  existing  line  of  steam  railroad. 

W.  Nelson  Smith, 
Consulting  Electrical  Engineer, 
Winnipeg  Electric  Railway  Company. 


42 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  I 


cribere  are  iovited  to  use  this  department  as  a 
uring  authentic  information  on  tiectrical  and 
ubjects.  Questions  concerning  general  eneineer- 
ing  theory  or  practice  and  questions  regardmg  apparatus  or 
materials  desired  for  particular  ne:;ds  will  be  answered. 
.Specific  data  regarding  desigTi  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self-addressed,  stamped  en- 
velope should  accompany  each  query.  All  data  necessary  for 
a  complete  underst..nding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
as  the  necessary  information  is  available;  however,  as  each 
queston  is  answered  by  an  expert  and  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


1946   —    P.MJALLELING    Tk.\NSFOKMER,S— In 

an  industrial  plant  with  two  banks  of 
three  500  kv-a,  single-phase,  13  200  to 
2200  volt  transformers  connected 
delta-delta  to  separate  loads  on  a 
three-phase,  three-wire  system,  con- 
siderable trouble  is  experienced  from 
sudden  heavy  short  overloads.  If  all 
the  load  could  be  fed  from  one  bus 
the  diversity  factor  would  decrease 
this  trouble.  The  transformers  are  of 
the  same  design  and  are  guaranteed 
to  operate  successfully  in  parallel  with 
each  other.  What  is  the  general 
practice  in  this  regard  in  plants  which 
do  not  experience  our  trouble?  Would 
it  be  good  practice  in  our  case  to 
operate  the  transformer  banks  in 
parallel.  If  paralleling  is  out  of 
question,  what  is  the  best  form  of  pro- 
tection? Is  it  generally  considered 
necessary  for  transformers  of  this 
capacity  to  use  balanced  relays  (in 
addition  to  overload  relays)  to  protect 
against  trouble  in  the  transformer 
itself?  If  not,  what  form  of  protec- 
tion would  you  recommend?  Is  it 
possible  to  operate  two  transformers 
on  open  delta  in  parallel  with  three 
on  closed  delta?         w.A.D.   (Ontario) 

Industrial  loads  of  this  size  are  gen- 
erally supplied  from  one  bus.  There 
should  be  no  difficulties  experienced  in 
operating  these  loads  from  the  same 
bus.  It  is  not  generally  considered 
necessary  to  protect  transformers  of  this 
capacity  with  balanced  relays.  Sufficient 
protection  should  be  produced  with  auto- 
matic oil  circuit  breakers  in  both  the 
2200  volt  and  13  200  volt  lines  with 
short  time  setting  on  the  2200  volt 
circuit  breakers.  It  is  possible  to  operate 
an  open  delta  bank  of  transformers  in 
parallel  with  a  delta  bank  but  the  divi- 
sion of  load  is  not  very  good:  for 
instance,  the  transformer  in  the  delta 
bank  that  is  connected  to  the  open  phase 
of  the  V  bank  will  carry  130  percent 
load,  when  the  other  transformers  are 
carrying  normal  load.  See  article  on 
"Delta  and  fZ-connectcd  Transformers 
in  Parallel"  by  E.  C.  Stone,  in  the 
Journal  for  April,  1910,  p.  304.         J.f.p. 

1947 — R  E  L  A  T I V  E  Merits  of  Stop- 
watches— Please  discuss  the  essen- 
tial characteristics  of  a  good  stop 
watch  for  use  in  electrical  tests. 

M.M.  (Illinois) 
A  stop  watch  consists,  essentially,  of 
two  main  members — the  watch  proper  or 
time-keeper,  and  the  controlling  device 
or  starting,  stopping  and  retrieving 
mechanism.  The  watch  proper  need 
not  be  an  exceptional  time-keeper,  but 
it  is  important  that  it  be  of  such  material 
and  workmanship  as  will  ensure  rugged- 
ness  and  positive,  regular  action.  The 
controlling  device  is,  by  far,  the  more 
likely  to  give  trouble  and,  therefore,  is 
the  member  that  should  be  given  par- 
ticular consideration  in  selecting  a  stop 
watch.  Controlling  devices  employ 
either     friction     drive     or    gear     drive. 


Gear  drive  is  generally  more  positive 
and  reliable,  providing  there  are  suffi- 
cient number  of  gear  teeth  so  that  there 
will  be  a  delay  of  not  over  one-tenth  of 
a  second  in  starting  the  mechanism, 
therefore,  if  all  other  things  are  equal, 
this  class  is  to  be  preferred.  In  any 
case,  to  be  reliable,  there  must  be  no 
tendency  to  slip  or  lag  in  starting,  drift 
or  creep  when  stopping,  and  the  hand 
or  hands  must  be  returned  positively 
and  definitely  to  zero  when  the  stem  is 
depressed  in  retrieving.  In  order  that 
there  shall  be  no  confusion  in  reading, 
it  is  desirable  that  a  stop  watch  be 
simply  a  stop  watch  and  not  be  provided 
with  full  sized  minute  and  hour  hands. 
A  small  hand  to  mark  the  minutes  is 
sufficient.  T.s.  and  C.J. 

1948 — Delta  Con.vected  Transformer 
Loaded  at  Full  and  Half  Voltage — 
We  have  some  three-phase,  250  volt 
motors  which  I  would  like  to  operate. 
I  would  like  to  know  whether  1  could 
get  it  from  the  present  delta  trans- 
former connections  shown  in  Fig. 
(a).  Can  I  get  250  volt,  three-phase 
taps  from  this  without  interfering 
with  the  550  volt  motors  or  buck- 
ing the  transformers.  What  change 
should  I  make  to  cut  out  one  of 
these  transformers  temporarily? 

D.L.H.    (new   jersey) 

It  is  possible  to  operate  your  250  volt 
three-phase  motors  satisfactorily  across 
the  half  voltage  taps  of  your  550  volt 
transformer  secondary  without  inter- 
fering with  the  550  volt  motors,  pro- 
vided you  are  not  overloading  the  half- 


(b) 

FIGS.  1948   (a)    and   (b) 

voltage  taps.  If  half  the  rated  kv-a  of 
the  bank  is  connected  to  the  full  voltage 
leads  as  shown  in  Fig.  (a)  an  addi- 
tional load  of  32.5  percent  of  the  nor- 
mal rating  may  be  connected  to  the 
half  voltage  leads,  assuming  that  the 
two  loads  have  the  same  power-factor. 


When  using  only  a  three-phase  load, 
connected  to  the  half-voltage  taps,  the 
transformers  will  give  half  their  kv-a 
output  without  overheating.  With 
your  present  transformer  connections, 
it  is  quite  simple  to  cut  out  any  one  of 
the  three  transformers  and  still  have  a 
three-phase  systeiti.  By  disconnecting 
the  primary  terminals  A  any  one  of  the 
transformers  at  points  .\.  A'  as  shown 
in  FIG.  (b),  and  the  secondary  at  points 
B  B'  the  remaining  two  transformers 
will  be  connected  open  delta.         m.m.b. 

1949— Advantages  of  Electric  Drive— 
I  would  like  to  be  advised  how  to 
proceed  to  show  my  employer  in 
terms  of  dollars  and  cents  the  advan- 
tages which  electric  drives  have  over 
his  present  countershaft  and  belt 
drive  installation.  The  efficiency  of 
our  no  hp  steam  engine  is  low  even 
at  full  load,  and  as  the  engine  seldom 
operates  at  rated  full  load,  the  opera- 
ting effccicncy  is  very  low.  We  are 
using  some  of  the  steam  for  heating 
purposes.  Would  it  not  be  more  eco- 
nomical to  use  a  bleeder  turbine  ra- 
ther than  use  an  expansion  valve?  Is 
it  possible  to  buy  a  bleeder  turbine  of 
100  kw  capacity  ?  Would  it  be  possi- 
ble to  use  this  bleeder  condensing 
during  the  summer  months.  To 
what  extent  will  the  feasibility  of  the 
use  of  the  bleeder  condensing  and 
non-condensing  type  be  limited,  eco- 
nomically? Is  it  possible  to  buy 
small  size  motors  of  low  speed  on  the 
open  market?  The  speed  of  our 
main  shaft  is  about  200  r.p.m.  How 
can  I  calculate  the  power  lost  in  shaft 
and  belt  drives? 

M.   W.   D.    (new  YORK) 

An  approximation  of  the  power 
losses  in  the  shafting  and  belting  may 
be  made  by  running  the  machinery 
without  load  and  determining  the 
horse-power  of  the  steam  engine 
by  means  of  indicator  cards.  There 
should  be  from  15  percent  to  50  percent 
saving  in  changing  from  line  shafting  to 
electric  motor  direct  drive.  Having  in 
mind  the  capacity  at  which  the  turbine 
would  operate,  the  conditions  suggest 
that  an  economical  noncondcnsing  tur- 
bine unit  exhausting  at  a  back  pressure 
satisfactory  for  heating  purposes, 
would  be  the  best  solution.  We  do  not 
know  of  any  bleeder  turbines  of  this 
capacity.  If  one  were  obtainable,  its 
condenser  auxiliaries  would  consume 
an  abnormally  large  percentage  o!  the 
steam  saved  by  condensing  operation. 
The  use  of  high-pressure  live  steam  fcr 
heating  purposes  is  always  uneconomi- 
cal. Desirable  speeds  for  motors  for 
machine  tool  applications  are  given  in 
Mark's  Mechanical  Engineers'  Hand 
book,  page  1418.  A  motor  of  200  r.p.m 
would  be  'Seldom  used,  as  it  would  be 
too  expensive  to  build .  Speeds  be- 
tween 900  and  1800  r.p.m.  on  the  ma- 
chines   are    generally    required.     Wood 


January,   1921 


THE   ELECTRIC  JOURNAL 


43 


working  machines  are  essentially  liigh 
speed,  except  in  a  very  few  cases. 
These  motors  are  obtainable  on  the 
open  market.  l.h. 

1950 — VoLT.^GE  Fluctuations  Causing 
Direct-Current  Motor  Troubles  — 
At  the  end  of  a  600  volt  direct-cur- 
rent feeder  we  have  a  100  hp  com- 
pound woimd  motor  driving  some 
line  shafting.  An  intermittent  load 
at  other  points  on  this  feeder  causes 
severe  voltage  fluctuations,  some- 
times pulling  it  as  low  as  400  volts 
when  suddenly  the  load  will  be  cut 
off,  causing  a  surge  which  results  in 
flashing  at  the  motor  in  question 
and  tripping  the  circuit  breaker, 
which  is  set  at  50  percent  overload. 
Aside  from  the  installation  of  addi- 
tional feeder  or  the  application  of 
low  voltage  release  to  the  circuit 
breaker,  is  there  any  way  of  stopping 
the  inrush  of  current  to  the  motor? 
I  have  in  mind  the  insertion  of 
a  choke  coil  and  if  you  think  this 
will  prove  successful  will  you  please 
suggest  a  design. 

i.j.s.  (new  York) 

The  condition  described  is  caused  by 
the  large  amount  of  current  that  flows 
when  the  voltage  rises.  The  motor  is 
running  at  a  speed  which  gives  a 
counter  e.m.f.  corresponding  to  a  400 
volt  supply  line.  When  increased  to 
600,  the  voltage  causes  a  rush  of  cur- 
rent which  the  motor  can  not  conimu- 
tate.  The  normal  current  for  a  100  hp, 
600  volt  motor  is  approximately  135 
amperes.  Assuming  the  line  drop  is 
ten  percent  or  60  volts,  and  applying 
Ohm's  law,  we  have  a  line  resistance  of 
0.45  ohms.  Now,  on  a  rise  from  400 
to  600  volts,  the  current  which  flows  is 
due  to  the  difference  between  line  and 
counter  volts.  Assuming  counter  volts 
to  be  ninety  percent  of  low  line  voltage 
600-360 


connecting  the  motor  directly  to  the 
line.  There  may  be  cases  where  one 
step  of  resistance  will  not  entirely 
eliminate  flashing,  but  two  or  three 
steps  may  be  required.  This  will  be 
dependent  on  local  conditions,  and  com- 
plete data  as  to  voltage  variation,  line 
and  armature  resistance  and  other 
points  will  be  required  to  determine 
this.  The  series  coil  may  be  differen- 
tially connected  in  which  case  it  should 
be  changed  so  as  to  add  to  the  effect  of 
the  shunt  coil.  Increasing  the  number 
of  series  turns  might  improve  condi- 
tions somewhat.  a.uh. 

1951 — Synchronizing  Two-Phase  to 
Three-Phase  Lines — Would  it  be 
possible  to  use  the  potential  trans- 
formers connected  as  indicated  in 
Fig.  (a),  and  by  grounding  e,  to  syn- 
chronizing between  d  and  d' ,  assum- 
ing positive  polarity.  The  grounds 
of  the  potential  transformers  at  A 
and  B  cannot  be  changed.  What 
provision  can  be  made  so  that  a  satis- 
factory synchronizing  connection  can 
be  made  between  the  high  and  low 
voltage  sides?  c.o.D.    (new  vork.) 

Assuming  that  power  is  supplied  to 
the  2300  volt  lines  from  some  other 
source  in  addition  to  the  70000  volt, 
three-phase,  2300  volt,  two-phase  bank 
of  transformers  shown,  and  that  it  is 
necessary   to   synchronize   the   two   lines 


lines  ;  and  4;  the  other  clement  of  the 
meter  should  be  connected  in  lines  2 
and  3.  Kefer  to  article  in  the  journal 
for  March  1919,  on  Three-Phase  to 
Two-Phase  Transformation  for  discus- 
sion of  methods  of  transforming  from 
three-phase  to  two-phase  or  vice  versa. 


or  360  volts,   the   current 


0.4S 


535  amperes.  This  is  four  times  full- 
load  rating  of  the  motor.  On  account 
of  the  high  voltage  and  mechanical 
limits  as  to  the  number  of  commutator 
bars,  the  voltage  per  bar  is  high  and  it 
is  relatively  easy,  compared  to  a  lower 
voltage  motor,  to  cause  the  motor  to 
flash  over  under  the  conditions  as  out- 
lined. The  above  calculations  are 
given  as  an  illustration,  and  are  onlv 
approximate.  On  account  of  the  time 
required  for  the  motor  to  accelerate 
from  the  400  volt  speed  to  the  600  volt 
speed,  a  choke  coil  will  lose  its  effec- 
tiveness before  the  counter  e.m.f.  has 
increased  enough  to  hold  the  current 
back.  To  protect  the  motor  under 
these  conditions  a  resistor  shunted  by  a 
contactor,  a  low  voltage  relay  and  an 
accelerating  relay  seem  to  offer  the 
most  satisfactory  solution.  The  volt- 
age relay  should  be  adjusted  to  open 
when  the  voltage  has  dropped  to  that 
value  below  which  it  will  cause  flashing 
when  it  rises  to  normal.  To  be  on  the 
safe  side,  this  should  be  considerably 
above  the  voltage  that  ordinarily  will 
cause  flashing.  When  this  relay  opens, 
it  will  open  the  contactor,  cutting  in  the 
resistor.  The  resistor  will  lower  the 
speed  slightly.  When  voltage  returns 
to  normal,  the  voltage  relay  will  close, 
bringing  the  accelerating  relay  into 
action.  When  the  motor  has  acceler- 
ated to  the  proper  point,  the  contactor 
will  be  closed  by  the  accelerating  relay, 


fig.  1951   (a) 


before    connecting    them    together,    syn- 
chronizing can  be  done  between   d  and 
d'    with   the  connections   shown,   if   the 
transformers  have  the  correct  polarity. 
J.  v.  p. 

1952 — Metering  Load  on  Secondary  of 
Taylor  Connection — In  Fig.  (a) 
both  two  and  three-phase  motors  and 
lights  are  connected  to  the  trans- 
formers. Will  the  two  watthour 
meters  register  the  correct  amount  of 
current  used.  I  understand  this  is  a 
special  transformer  and  the  connec- 
tion is  called  the  Taylor  connection. 
Any  other  information  regarding  ef- 
ficiency, etc.,  will  be  appreciated. 

j.p.v.  (minn.") 
The  meter  and  two-phase  motor,  as 
shown  in  the  wiring  diagram  Fig.  (a) 
are  incorrectly  connected.  The  Taylor 
connection  is  shown  in  Fig.  (b).  Two- 
phase  power  may  be  taken  from  points 
J-4  and  2-3;  three-phase  power  from 
points  2-3-4.  To  measure  the  power  in 
the  three-phase  motor  circuit  the  watt- 
hour  meter  shunt  coil  connected  to 
points  I  and  2  should  be  connected  to 
points  2  and  4.  The  watthour  meter 
will  then  be  connected  properly  to  mea- 
sure the  three-phase  power.  It  is 
impossible  to  measure  the  two-phase 
and  three-phase  power  with  the  one 
watthour  meter.  To  measure  the  two- 
phase  power  one  element  of  a  poly- 
phase   meter    should    be    connected    to 


FIGS.  1952  (a)  and  (b) 

The  total  power  can,  of  course,  be  mea- 
sured on  the  primary  side  of  the  main 
transformers,  by  a  three-phase  meter 
and  suitable  instrument  transformers. 
It  would  be  better,  however,  to  install 
two  separate  meters  in  the  two  circuits. 

A.R.R. 

1953 — Steel  Conductors — In  the  con- 
struction of  a  250  volt,  2500  ampere 
feeded  line,  I  am  considering  the  use 
of  four  80  pound  (to  the  yard)  steel 
railroad  rails,  two  rails  for  each  pol- 
arity and  spacing  each  set  lour  feet 
apart.  The  entire  distance  of  rail 
conductors  to  be  75  feet,  and  for 
the  remainder  of  the  distance  or  150 
feet,  using  four  I  000  000  circ.  mil 
copper  cables.  My  intention  is  to 
install  the  rails  in  a  tunnel,  the  height 
of  which  is  six  feet,  therefore  allow- 
ing four  feet  spacing.  I  should  be 
pleased  to  obtain  data  on  the  com- 
parison of  conductivity  of  steel  and 
copper;  also,  allowable  magnetizing 
distances  for  steel  parallel  con- 
ductors, and  heat  losses  of  relative 
spacing.  d.f.z.    (Kansas) 

The  parallel  resistance  of  two  80 
pound  steel  rails  75  feet  long,  is  0.00047 
ohms.  The  parallel  resistance  of  four 
I  000000  circ.  mil  copper  cables,  150 
feet  long,  is  0.000432  ohms.  We  are 
assuming  here  two  steel  rails  in  each 
side  of  the  circuit  and  four  cables  in 
each  side.  The  total  drop  for  both 
sides  of  the  circuit  is  then  4.5  volts  at 
2500  amperes,  or  1.8  percent.  The  PR 
loss  at  2500  amperes,  is  about  40  watts 
per  foot  for  the  two  paralleled  rails. 
Therefore,  we  should  estimate  that  the 
rails  would  rise  to  a  temperature  of 
about  18  to  20  degrees  C,  while  carry- 
ing 2500  amperes  in  the  circuit,  assum- 
ing still   air.     The  comparative  conduc- 


41 


THE   ELECTRIC  JOURXAL 


Vol.  XVIII,  No.   I 


tivity  of  the  average  steel  used  in  rails 
compared  to  ordinary  copper,  is  about 
7.5  to  10  percent.  By  the  "allowable 
magnetizing  distances",  we  assume  is 
meant  permissible  spacing  from  the 
standpoint  of  the  stresses  on  the  con- 
ductor. With  2500  amperes  and  a  spac- 
ing of  four  feet  as  proposed,  the  pres- 
sure per  foot  on  both  rails  on  each  side 
of  the  circuit  will  be  0.07  pound  per 
foot,  or  0.035  pounds  per  rail.  These 
pressures  vary  inversely  as  the  spacing 
between  conductors  and  directly  as  the 
square  of  the  current.  Therefore,  the 
stress  under  short-circuit  conditions 
with  any  assumed  value  of  current  and 
spacing  of  conductors  can  be  readily 
calculated.  In  general  it  may  be  stated 
as  a  rule  that,  when  a  direct-current 
supporting  structure  is  strong  enough 
to  hold  the  heavy  direct-circuit  leads 
under  normal  conditions,  it  is  heavy 
enough  to  prevent  serious  damage 
under  short-circuit  conditions.  The 
heat  losses  of  the  conductors  above  are 
independent  of  the  spacing,  as  long  as 
this  spacing  is  sufficient  to  permit 
ready  dissipation  of  the  heat.  All  of 
the  above  discussion  assumes  direct 
current,  which  we  believe  is  intended  m 
the  present  case.  With  alternating  cur- 
rent, the  heating  would  depend  upon 
the  frequency,  material  of  conductor, 
form  of  cross-section,  spacing,  etc. 
Rails  must  be  welded  or  well  bonded. 

K.C.S. 

1954 — St.\rting     Sy.vchronous     Motor 
AS  AN  Induction   Motor — In  starting 
up   synchronous   motors   as    induction 
motors,  in  some  installations  the  open 
delta  connection  is  used   for  starting, 
going  over  to  closed  delta  at  running 
as  shown  in  Fig.   (a).     What  are  the 
advantages  derived  by  using  this  con- 
nection? G.H.    (calif.) 
This    arrangement    makes    it    possible 
to  connect  the  transformers  permanently 
in  delta  for  the  running  voltage  and  to 
start  the  motor  from  taps  on  the  same 


In  switching  transformers  that  operate 
in  parallel  with  other  banks,  the  best 
procedure  is  as  follows : — To  remove  a 
bank  from  service,  first,  disconnect  the 
high-voltage  side,  then  the  low-voltage 
side.    To  put  a  bank  into  service,  first 


FIG.  1954  (a) 

transformers.  Also,  it  permits  the  use 
of  a  double-pole,  double-throw  switch, 
changing  the  connections  of  only  two  of 
the  motor  leads.  j.bg. 

1955 — Switching  Large  Transformers 
— Assuming  that  it  is  equally  con- 
venient to  use  either  method,  which 
way  is  best  to  cut  out  a  10  000  kv-a, 
three-phase,  no  000  to  6600  volt  trans- 
former that  is  connected  to  a  large 
transmission  network  and  is  operating 
in  parallel  with  other  large  three- 
phase  transformers,  a  few  of  which 
have  the  neutral  solidly  grounded : — 
To  open  the  low-tension  switch  first, 
and  the  high-tension  switch  last,  or 
vice  versa?  In  cutting  in  this  trans- 
former, which  method  is  preferable, 
to  close  in  the  low-tension  switch  first 
or  the  high  tension  sw^itch  first?  In 
cutting  in  large  transformers,  some- 
times a  very  hea\'y  charging  current 
flows  for  a  moment.  If  the  trans- 
former were  closed  in  on  the  high- 
tension  side  first,  would  the  choke 
coils  shown  in  Fig.  (a')  appreciably 
reduce  the  magnitude  of  this  rush  of 
charging  current?  r.r.g.   (mont.) 


FIG.  1955   (a) 

connect  the  low-voltage  side,  then  the 
high-voltage  side.  If  the  choke  coils 
relerred  to  are  large  enough  to  reduce 
the  switching  surge  appreciably,  they 
will  produce  a  considerable  drop  in 
voltage  during  normal  operation. 

H.F.P. 

1956 — Nicholson  Arc  SuppRESsoR-What 
is  the  Nicholson  arc  suppressor,  and 
how  does  it  work? 

P.N.P.    (KENTUCKY) 

The  Nicholson  arc  suppressor  is  for 
the  purpose  of  suppressing  arcs,  such  as 
arc  usually  caused  by  lightning  dis- 
charges on  a  transmission  system.  If 
the  neutral  of  the  system  is  grounded, 
or  if  it  is  large  enough  so  as  to  have  a 
heavy  charging  current  to  ground,  an 
insulator  which  flashes  over  will  cause 
an  arc  to  form.  The  arc  suppressor 
consists  of  three  single-pole  switches 
usually  placed  at  the  main  generator 
station,  and  so  arranged  that  whenever 
an  arc  occurs  between  one  wire  and 
ground,  the  switch  on  that  phase  wire 
will  close  for  an  instant  and  ground  the 
wire,  thus  short-circuiting  the  arc  so 
that  it  will  be  extinguished.  This  clears 
the  system  without  the  necessity  of  dis- 
connecting ihc  part  of  the  circuit  which 
is  in  trouble.  The  single-pole  circuit 
breakers  which  form  the  suppressor  arc 
usually  actuated  by  a  series  coil  in  the 
main  line,  so  that  they  operate  whenever 
an  excessive  current  flows.  Sometimes 
they  are  actuated  by  potential  relays 
which  operate  to  close  the  switch  on  one 
wire  when  the  potential  on  that  wire 
falls  to  zero.  In  this  case  the  relays  and 
the  switch  mechanisms  are  usually  inter- 
locked so  that  only  one-phase  can  be 
grounded  at  a  time.  The  first  installa- 
tions of  this  device  were  operated  by 
current  coils,  and  were  intended  to  clear 
short  circuits  between  wires  as  well  as 
between  a  single  w-ire  and  ground. 
This  method  of  protecting  transmission 
systems  has  not  jjeen  used  to  any  great 
extent,  probably  because  lightning  dis- 
turbances frequently  involve  more  tha;i 
one-phase  wire,  thus  resulting  in  short- 
circuits.  This  necessitates  setting  the 
protective  relays  ver>'  high,  so  as  to 
allow  the  arc  suppressor  to  operate 
before  the  relays  will  start  to  sectional- 
ize  the  system.  In  case  the  short-circuit 
is  of  such  a  nature  that  the  arc  sup- 
pressor cannot  clear  the  trouble,  th» 
resultant  delay  due  to  the  slow  action 
of  the  sect'onalizing  relays  may  cause 
all  the  load  to  be  lost,  before  the  trouble 
is    cleared.     Present    practice    indicates 


that  best  results  are  obtained  by  the  use 
of  a  good  system  of  automatic  sectional- 
izing  which  will  cut  out  defective  sec- 
tions of  the  network.  Individual  feeders 
can  best  be  protected  by  means  of  the 
Ricketts  service  restoring  scheme  which 
trips  out  the  circuit  breaker  and  im- 
mediately recloses  it.  This  momentary 
interruption  to  the  circuit  is  sufiicicnt  to 
break  any  arc  which  may  have  been 
established  and  the  service  can  easily  be 
lestored,  without  causing  an  interruption 
of  more  than  one  second.  l.n.c.  ■ 

1957— Connections  of  Reactive  Meter 
—Please  give  me  a  proper  diagram  of 
connections  of  a  Westinghousc  type 
S.  I.  reactive  meter,  including  a  dia- 
metric sketch  of  the  arrangement  of 
coils  inside  the  meter,  etc.  What  is 
the  effect  of  reversing  the  current 
clement?  What  is  the  effect  of  inter- 
changing the  voltage  leads? 

o.a.l.   (Maryland) 

The  diagram  of  connections  for  the 
Wcstinghouse  type  SI  reactive  factor 
meter  is  as  shown  in  Fig.  (a).  The 
connections  are  for  a  three-phase  re- 
active-factor or  power- factor  meter, 
these  two  meters  being  exactly  the  same 
except  the  scale  calibration,  which  in- 
dicates the  cosine  of  the  phase  angle  in 
the  case  of  the  power- factor  meter,  an  J 
the  sine  of  the  angle  in  the  case  of  the 
reactive- factor  meter.  The  connections 
for  the  single-phase  and  two-phase 
meter  are  similar  to  the  above,  except 
that  the  coils  which  provide  the  rotating 
field  are  wound  with  an  angle  of  90 
degrees  between  them  instead  of  120 
degrees  as  above,  and  a  reactance  is 
inserted  in  series  with  one  of  these 
coils  in  the  case  of  the  single-phaso 
meter  to  give  the  rotating  field.  Until 
a  few  years  ago,  the  reactive  meter  was 
so  designed  that  the  rotating  field  was 
furnished  by  three  current  coils  con- 
nected in  star,  and  the  moving  vane  was 
magnetized  by  a  potential  coil ;  whereas 
in  the  latest  type  meter,  as  indicated  in 
Fig.  (a),  the  potential  coils  furnish  the 
rotating  field,  and  a  current  coil  mag- 
netizes the  moving  vane.  This,  how- 
ever, does  not  affect  the  discussion 
which  follows.  The  effect  of  inter- 
changing the  current  leads  is  to  reverse 
the  polarity  of  the  field  of  the  magnet- 


winng  uiagnim  l^aus  Sdmnatic  Dopam 

FIG.  I9S7  (a) 

izing  coil,  and  this  will  reverse  the  posi- 
tion of  the  pointer  on  the  scale  exactly 
180  degrees.  The  effect  of  reversing 
any  two  of  the  voltage  leads  is  to  change 
the  position  of  the  pointer  through 
approximately  no  mechanical  degrees, 
in  the  case  of  a  three-phase  meter  and 
hence  'o  cause  it  to  give  an  erroneous 
indication.  Theoretically,  the  pointer 
should  be  offset  through  120  mechanical 
degrees  in  the  latter  case.  This  varia- 
tion, however,  is  caused  by  the  fact  that 
the  current  in  the  magnetizing  coil  ha^ 
a  slight  lag.  due  to  the  fact  that  it  is 
wound  on  an  iron  core.  Hence,  when 
calibrating,  the  moving  coil  is  allowed 
to  take  its  position  for  a  given  condition 


January,   1921 


THE  ELECTRIC  JOURNAL 


45 


of  power-factor,  and  the  pointer  is  then 
slipped  ahead  a  lew  degrees  on  the 
shaft  to  compensate  for  this  lagging 
current.  Hence,  when  the  direction  of 
field  rotation  is  changed,  as  when  two  of 
the  voltage  leads  are  exchanged,  the 
effect  is  to  introduce  a  variation  in 
indication  which  is  equal  to  twice  the 
amount  that  the  pointer  was  moved 
ahead  when  the  meter  was  calibrated. 

H.P.S. 

1958 — Mercury  Arc  Rectifier — What 
can  be  done  to  a  mercury  arc  rectifier 
rated  at  220  volts,  60  cycles,  alternat- 
ing current,  1 10  volts,  30  amperes 
direct  current,  to  reduce  the  charging 
rate  to  five  amperes  on  a  storage 
battery  load  and  still  maintain  the  arc 
in  the  mercury  tube? 

H.p.w.  (Indiana) 

From  the  statement  of  the  question  it 
appears  that  the  difficulty  lies  in  the 
failure  of  the  outfit  to  operate  at  low 
currents.  This  failure  is  due  to  the 
pulsations  in  the  direct  current,  which 
bring  the  current  at  times  below  the 
value  at  which  the  arc  is  stable.  This 
trouble  can  be  corrected  by  increasing 
this  low  point,  either  by  increasing  the- 
total  current  or  by  adding  sufficient 
inductance  in  the  direct-current  circuit 
to  reduce  the  amplitude  of  the  pulsa 
tions.  The  simplest  method  is  to  add  a 
shunt  resistance  which  will  increase  the 
total  current  and  thereby  increase  the 
minimum  value.  The  addition  of  iti- 
ductance  in  the  direct-current  circuit 
involves  higher  initial  expense  but  re- 
sults in  more  economical  operation,  in 
that  the  loss  in  the  shunt  resistance  is 
eliminated.  The  choice  between  the 
two  methods  depends  upon  the  operating 
conditions,  such  as  cost  of  power,  and 
the  amount  of  service  which  is  required. 
Without  definite  information  as  to  the 
design  and  characteristics  of  the  recti- 
fier, we  cannot  advise  what  inductance 
should  be  U5ed,  but  it  is  probable  that  a 
coil  of  o.oi  henrys  would  give  satis- 
factory operation.  There  should  be  an 
air-gap  in  the  magnetic  circuit- of  this 
coil.  A.L.A 

1959 — Conductor  H.wing  a  High  Nega- 
tive Coefficient  of  Resistance — Can 
you  tell  me  of  any  material  which  has 
a  high  negative  coefficient  of  re- 
sistance? I  would  like  to  get  some 
alloy  which  has  at  70  degrees  F..  a 
very  high  resistance  and  at  200  de- 
grees F.  a  very  low  resistnnce.  T 
do  not  know  of  any  such  alloy  and 
am  afraid  that  there  is  nothing  which 
will  fulfill  these  requirements.  How- 
ever, I  am  wondering  if  there  is  not 
some  kind  of  powder  or  paint  which 
could  be  deposited  on  some  insulating 
carrier,  say  a  piece  of  pasteboard  or 
fish  paper,  which  would  answer  these 
requirements,  that  is,  an  exceptionally 
high  resistance  at  70  degrees  F.  and 
a  comparatively  low  resistance  at  200 
degrees  F.  l.a.f.  (mass.) 

The  class  of  electrical  conductors  to 
which  you  refer,  having  a  large  nega- 
tive coefficient  of  resistance,  is  called 
pyro-electric  conductors.  Such  materials 
are  case  silicon,  boron,  magnetite,  sul- 
phides and  carbides."  Most  of  them 
probably  do  not  have  a  sufficiently  largo 
negative  temperature  coefficient  to 
answer  your  purpose.  Possiblv,  how- 
ever, silver  sulphide  would  fill  your" 
needs.  Fitzgerald  reports  data  on  a 
sample  having  the  following  character- 
istics : — 


This  material  has  a  critical  tempera- 
ture above  which  the  resistance  is  very 
small.  This  temperature  depends  upon 
the  copper  content.  For  pure  silver 
sulphide  the  critical  temperature  is  170 
degrees  C.  (338  degrees  F.)  ;  with  0.5 
percent  copper,  it  is  163  degrees  C.  (325 
degrees  F.)  ;  and  with  7.5  percent 
copper,  it  is  104  degrees  C.  (219  degrees 
F.).  This  conductor  must  be  used  with 
alternating  current,  as  direct  current  re- 
duces some  of  the  sulphide  to  metallic 
silver  and  the  material  then  becomes  a 
good  conductor  at  all  temperatures.  If 
it  is  possible  to  use  sufficient  current 
through  the  conductor  to  heat  it  appre- 
ciably, the  effective  critical  point  can  be 
varied  at  will  by  varying  the  amount  of 
the  current.  It  is  possible  that  you  can 
obtain  silver  sulphide  in  usable  form 
from  the  Fitzgerald  Laboratories.  Other 
wise  you  had  probably  better  make  it 
yourself.  We  believe  that  Fitzgerald's 
7.5  percent  copper-silver-sulphide  is 
made  by  heating  an  alloy  of  02.5  percent 
silver  and  7.5  percent  copper  in  a  bath 
of  molten  sulphur.  The  resulting 
sulphide  is  cast  and  then  machined  into 
a  rod.  If  desired  the  sulphide  may  be 
rolled  into  strips,  but  this  rolling  must 
be  done  cold.  If  the  material  is  worked 
hot,  even  at  as  low  a  temperature  as  200 
degrees  C.  the  electrical  characteristics 
are  entirely  changed.  The  sulphide  will 
then  have  a  temperature  coefficient  of 
approximately  zero  instead  of  a  large 
negative  value.  According  to  the 
Bureau  of  Standards,  silver  sulphide 
may  be  made  by  melting  the  chemically 
prepared  powder  in  a  porcelain  crucible, 
tightly  covered  to  prevent  oxidation. 
The  melting  point  is  approximately  82=; 
degrees  C.  For  further  details  see  the 
Transactions  of  the  American  Electro- 
chc'iiical  Society  for  1014,  p.  303;  also 
Bureau  of  Standards  Bulletin,  Vol.  14, 
P   331-  T.s. 

KiCio— Reconnecting  Three-Phase,  2200 
Volt  Alternator  to  Two-Phase, 
2200  Volts — The  writer  had  occasion 
to  reconnect  a  three-phase  alternator, 
connected  twelve  pole  series  delta  to 
two-phase  series.  The  three-phase 
voltage  originally  was  2200  volts  and 
it  was  desired  to  reconnect  for  2200 
volts,  two-phase.  The  voltage  work- 
ing out  rather  high,  it  was  decided  to 
rut  nut  12  of  a  total  of  72  coils. 
These  coils  were  equally  divided 
throughout  the  machinue,  which  cut 
out  every  sixth  coil  of  the  stator 
winding.  The  balance  of  the  coils 
were  then  connected  in  groups  of 
3-2,  2-3,  etc..  and  the  long  group  con- 
nection was  used,  namely,  going  once 
around  the  machine  and  taking  in  all 
the  North  pole  groups,  then  comint; 
back  and  taking  in  all  the  South  pole 
groups  of  each  phase.  This  alter- 
nator so  connected  w^s  put  on  a  motor 
load  entirely,  two-phase,  4  wire,  and 
it  was  found  that  the  phases  were 
considerably  unbalanced  at  full  load, 
the  current  read  on  one-phase  being 
30  amneres  and  on  the  other  phase  .S-] 
amperes.  It  was  first  believed  that 
the  grouping  was  done  incorrectlv,  but 
on  checking  it  was  found  to  he 
correct.     It  was,  therefore,  decided  to 


put  in  all  the  coils  throughout  the 
machine,  bringing  down  the  saturation 
considerably,  with  the  result  that  the 
phases  balanced  correctly.  The  writer 
would  like  to  know  why  the  phases 
were  unbalanced  with  the  grouping 
and  coils  cut  out. 

G.p.E.  (new  jersey) 
Your  idea  of  cutting  out  certain  coils 
to  increase  the  saturation  is  all  right. 
However,  the  dead  coils  of  your  dia- 
gram in  Fig.  (b)  are  not  symmetrically 
placed  with  respect  to  the  two  phases 
and  the  resultant  angle  between  the 
voltages  of  the  two  phases  is  displaced 
from  00  degrees.  In  this  particular  case 
the  angle  is  107  degrees  which  means  a 
relative  displacement  of  17  degrees. 
As  you  have  indicated,  the  currents  of 
the  two  phases  are  unbalanced  and  the 
power  outputs  are  different.  Fig.  (b) 
represents  the  connections  as  they  were 


figs,   i960   (a),    (b)   and   (c) 


with  a  dead  coil  every  sixth  slot.  The 
two  phases  are  distributed  over  only 
five  slots  and  are  thus  crowded  together. 
The  voltage  diagram  shown  in  Fig.  (a) 
shows  the  vectorial  relations  of  the 
voltages  of  the  various  slots,  the  re- 
sultant voltages  of  the  two  phases  are 
A,  and  B,.  Fig.  (c)  is  a  proposed 
balanced  condition.  The  dead  coils  arc 
unevenly  spaced  with  reference  to  the 
slots — that  is  they  lie  in  slots  6,  Q,  18, 
21,  JO,  etc.  The  coils  of  the  two  phases 
are  distributed  the  proper  distance  apart 
and  the  voltages  of  the  two  phases 
correspond  to  Ai  and  Bj  of  Fig.   (a). 

E.B.? 

1061 — Grounded  Transmission  Lines — 
A  transmission  line  of  81  kilometers 
has  a  pressure  of  88000  volts,  the 
transformers  are  connected  delta- 
delta,  and  the  alternator  is  connected 
star  with  the  neutral  point  grounded. 
The  voltage  is  stepped  up  from  6000 
to  So 000  giving  a  ratio  of  14.6.  If 
one  of  the  transmission  lines  becomes 
grounded,  what  will  the  voltage  on 
the  other  wires  be;  also  what  effect 
will  this  have  on  the  low-voltage  side 
of  the  transformer?  Will  the  low 
voltage  be  increased  considerably? 
By  connecting  only  one  wire  of  the 
above  transmission  line,  that  is,  ener- 
gizing only  one  wire  and  leaving  the 
other  two  open  at  the  station,  we 
obtain  a  true  signal  for  ground  in  the 
section  where  this  line  is  connected. 
There  are  600  insulators  of  2000 
megohms  each  in  each  line  and  the 
wires  which  were  left  open  had  only 
about  20  station  insulators  for  each 
line.  What  would  the  voltage  from 
the  energized  wire  to  ground  be  in 
this  case?  j.A.v.  (urazil) 


THE   ELECTRIC  JOURNAL 


Vol.  X\'III,  No.  I 


The  fact  that  the  generator  neutral  is 
grounded  has  practically  no  effect  on  the 
high-voltage  side  of  the  transformers, 
and  the  transmission  line  is  operating 
with  a  free  neutral.  If  the  line  capa- 
cities are  balanced,  the  voltage  of  each 
line  to  ground  will  be  46000  volts  and 
the  charging  currents  in  the  three  wires 
will  be  equal.  When  one  line  is 
grounded,  the  voltage  of  the  other  two 
lines  to  ground  will  be  80000  volts. 
The  charging  current  in  these  two  con- 
ductors will  be  increased  about  30  per- 


cent each  and  in  the  grounded  con- 
ductor it  will  be  approximately  double 
normal.  Now  if  only  one  conductor  is 
connected,  it  will  tend  to  come  to  a 
lower  potential  to  ground  than  normal, 
the  amount  of  change  being  dependent 
upon  the  relative  capacity  of  this  line 
and  that  of  the  remainder  of  the  system 
still  connected.  If  there  is  little  capacity 
in  the  remainder  of  the  system  the 
conductor  will  approach  ground  poten- 
tial and  the  terminals  of  the  other  con- 
ductors   will    approach   80000   volts    to 


ground,  which  is  the  condition  holding 
in  the  case  of  a  grounded  conductor. 
The  grounding  of  one  of  the  lines  on 
the  high-voltage  side  of  the  transformer 
will  not  effect  the  lines  on  the  low- 
voltage  side  as  they  are  two  distinct  and 
separate  circuits,  well  insulated  from 
each  other.  The  true  signal  for  ground 
is  due  to  the  condenser  effect  of  the 
charged  line,  which  depends  upon  the 
relative  capacity  of  this  line  and  that  of 
the  remainder  of  the  system  still  con- 
nected. A.VV.C. 


EAKLWAY  ©FEEATM^  ©ATA 

The    purpose    of    this    section    is    to    present         The   cooperation   of  all   those   interested    in 
accepted  practical  methods  used  by  operating         operating  and  maintaining  railway  equipment 
companies   throughout   the    country                       is    invited.      Address    B.    O.    D.    Editor. 

THE 
ELEQRIC 
JOURNAL 

JANUARY 
1921 

Types  of  Transition  Used  to  Obtain   Series-Parallel  Operation 


In  the  early  forms  of  railway  control,  straight  rhcostatic 
notching  was  employed  to  obtain  acceleration.  The  motors 
were  connected  permanently  in  parallel,  and  the  resistance  was 
cut  out  notch-by-notch,  until  the  trolley  voltage  was  applied 
directly  to  the  motors.  Although  this  method  of  operation 
gives  the  simplest  form  of  connection  with  the  simplest  design 
of  controller,  it  had  one  inherentlx  bad  characteristic.  As  all 
the  motors  are  in  parallel,  the  starting  current  is  the  sum  of 
the  currents  in  all  the  motors.  The  resistance  must  have  suffi- 
cient capacity  to  carry  this  current  throughout  the  acceleration, 
requiring  a  resistor  of  heavy  design,  and  producing  high  re- 
sistance losses.  Hence  it  was  deemed  advisable  to  use  a  system 
where  the  motors  would  be  connected  first  in  series  and  then 
in  parallel,  in  order  to  reduce  the  current  on  starting. 

With  the  series-parallel  system  of  control,  the  transition 
point  is  the  point  of  change  from  the  series  connection  to  the 
parallel  connection  of  the  motors. 

TYPES  OF  TRANSITION 

Three  general  types  of  transition  have  been  employed  in 
railway  control  apparatus,  as  follows: — 


FIG.    I — OPEN    CIRCUIT   TRANSITION 
Fir,.    2 — SHUNTING   TRANSITION 
FIG.    3 — BRIDGING   TRANSITION 

Open  Circuit  Transition — The  first  series-parallel  control 
employed  the  so-called  open  circuit  transition.  With  this  con- 
nection, when  going  from  scries  to  parallel  through  transition, 
the  motors  were  disconnected  from  the  line.  As  the  power  to 
the  motors  is  interrupted,  the  car  tends  to  lose  momentum  at 
this  instant.  When  power  is  again  applied  to  the  motors  in 
the  parallel  connection,  the  torque  is  renewed  suddenly,  causing 
jerk>'  action  of  the  cars.  This  form  of  transition  has  two  in- 
herently bad  characteristics : — 

1  Heavy  currents  are  broken  during  transition. 

2  The   motors   lose   torque    at   this   point.      This    is   particular  y 

bad  when  climbing  grades. 

Connections  during  transition  are  shown  in  Fig.   I. 


Shunt  Transilion — To  eliminate  the  undesirable  features 
of  the  open  circuit  transition,  a  scheme  of  connections  was 
devised,  whose  name  is  taken  from  the  shunting  connection 
employed.  One  of  the  motors  in  a  two-motor  equipment  or 
two  of  the  motors  in  a  four-motor  equipment  are  short-circuited 
in  transition.  In  this  case,  there  is  no  open  circuit,  biit  there 
is  a  loss  of  torque  on  the  motor  or  motors  shunted  out. 

So  far  as  the  question  of  torque  is  concerned,  this  method 
of  transition  is  better  than  the  open  circuit  transition,  as  half 
of  the  motors  are  delivering  torque  to  drive  the  car  wheels. 
There  being  no  open  circuit  during  transitiori,  one  of  the  most 
objectionable  features  found  with  the  open  circuit  transition 
where  heavy  currents  are  opened  is  eliminated.  The  method 
of  connections  for  this  type  of  transition  is  shown  in  Fig.  2. 

Bridging  Transilion — To  overcome  the  loss  of  torque  ob- 
tained in  both  the  open  circuit  and  shunt  transitions,  and  to 
obtain  a  greater  number  of  notches  for  locomotives  and  auto- 
matic equipments,  the  bridging  method  of  transition  was 
evolved.  With  this  connection,  there  is  no  loss  of  torque 
whatever  during  transition,  as  both  motors  are  connected  across 
the  line  at  the  same  time ;  in  fact,  an  increase  in  torque  can 
easily  be  obtained  during  this  period.  To  prevent  a  short- 
circuit  during  the  transition  period,  each  motor  or  pair  of 
motors  is  paralleled  with  a  section  of  the  starting  resistance. 
The  connection  between  the  two  motor  circuits  is  made  with  a 
switch  or  finger  and  contact  through  which  the  current  may 
flow  in  either  direction,  depending  upon  the  speed  at  which  the 
car  is  running,  and  the  value  of  the  resistance  used  to  parallel 
the  motors.  Connections  during  transition  for  this  scheme  are 
shown  in  Fig.  3. 

APPLICATION  OF  THE  DIFrEH.ENT  METHODS  OF 
TRANSITION 

J— Open  CiVcui'/— This  scheme  of  connection  is  only  being 
used  on  some  of  the  older  types  of  platform  controllers,  having 
been  superseded  by  the  shunting  or  bridging  schemes.  It  was 
limited  in  its  application  by  the  arcs  formed  during  transition. 

^_5/,i(H<!'Mfli— Practically  all  light  traction  equipments  using 
hand  control,  whether  of  the  platform  or  remote  type,  employ 
this  method  of  connections  for  changing  from  series  to  parallel. 
Some  of  the  smaller  tvpcs  of  locomotives  or  baggage  car  equip- 
ments, used  in  locomotive  service,  also  use  this  connection. 
When  cutting  out  motors  of  a  four  motor  equipment,  using 
shunt  transition,  it  is  advisable  to  see  that  the  motors  of  a 
pair  of  motors  cut  out  are  mounted  on  separate  trucks.  This 
is  to  make  sure  that  torque  will  be  applied  to  each  truck  during 
the  transition  period. 

^—Bridging— The  majority  of  automatic  equipments  in 
light  traction  ser\'ice,  and  also  locomotives,  use  the  bridging 
method  of  transition.  On  automatic  equipments,  the  operating 
characteristics  of  the  bridging  switch  as  affecting  the  control 
circuits  are' essential.  With  the  standard  hand  control  tj'pe 
where  shunting  transition  with  remote  control  switches  is  used, 
it  is  necessarj'  to  furnish  an  extra  piece  of  apparatus,  in  order 
to  obtain  automatic  control.  With  the  bridging  method  of 
transition,  it  is  unnecessary  to  pay  any  attention  to  the  method 
of  connecting  the  motors,  as  to  whether  each  pair  of  motors 
uses  one  motor  from  each  truck  or  not. 

H.  R.  Meyer. 


The  Electric  Journal 


VOL.   XVlll 


February.  1921 


No.  2 


The    booster-type    synchronous    con- 
Regulation       verter    has     now     held     undisputed 
^  possession  of  the  direct-current  light- 

Synchronous  .^^^  ^^^^  fg^  ^g„  yg^rs.  From  1908 
Converters  ^^  ^^^^  ^^  ^^^^^  ^^  split-pole  con- 
verter was  an  active  contender,  especially  in  25  cycle 
systems,  but  with  the  introduction  of  commutating 
poles,  about  191 1  and  the  rapid  extension  of  60  cycle 
systems  since  that  time,  serious  rivalry  has  disappeared. 
Recently  there  has  arisen  considerable  discussion 
among  central  station  engineers  as  to  whether  the  high 
performance  standards  and  flexibility  of  the  booster 
converter  are  justified  in  all  converter  applications,  and 
it  has  been  proposed  to  economize  on  the  first  cost  by 
using  a  simple  converter  and  obtaining  a  smaller  voltage 
range  by  reactance  and  shunt  field  current  control. 

There  is,  of  course,  nothing  new  in  the  use  of 
reactance  and  variable  excitation  for  obtaining  volt- 
age range.  It  is  one  of  the  oldest  methods  in  point  of 
use,  if  not  of  conception.  In  this  connection,  it  is  in- 
teresting to  note  that,  while  Chas.  F.  Scott  patented  the 
fundamental  idea  of  the  booster  converter  in  1893,  it 
was  not  until  1907 — thirteen  years  later — that  the  first 
application  to  Edison  service  was  made.  Messrs. 
B.  G.  Lamme  and  R.  D.  Mershon  (then  an  en- 
gineer with  the  Westinghouse  Company)  developed  the 
principle  of  reactance  control  in  1896  and  it  was  im- 
mediately applied  in  railway  service.  So  there  is  no 
new  problem  for  the  designer,  the  manufacturer  or  the 
operator.  It  is  simply  a  problem  of  application,  to 
analyze  the  characteristics  of  the  converter  operating 
under  variable  power- factor,  to  determine  permissible 
values  of  lagging  kv-a  that  can  be  supplied  by  the  trans- 
mission system  and  to  determine  the  necessar}'  range  in 
voltage  in  the  direct-current  system.  Briefly,  the  simple 
converter,  with  reactance  control,  is  at  its  best  in  loca- 
tions and  on  systems  where  the  drop  in  alternating  volt- 
age is  negligible,  where  the  desired  range  in  direct-cur- 
rent voltage  is  small — say  within  5  percent  above  and 
below  normal  converter  voltage — and  where  the  trans- 
mission system  can  supply  lagging  kv-a  equal  approxi- 
mately to  half  the  converter  kw  rating,  without  objec- 
tionable results.  Conversely,  the  good  qualities  of  the 
booster  converter  show  to  best  advantage  when  the  drop 
in  alternating  voltage  is  considerable,  when  a  wide 
range  in  direct-current  voltage  is  necessary  and  when 
operation  at  100  percent  power-factor  is  important. 

Mr.  Hague's  article,  in  this  issue  of  the  Journal, 
presents  an  analysis  of  the  characteristics  of  the  simple 
converter  with  reactance  voltage  control  that  should  be 
of  great  interest  and  value,  particularly  to  engineers  re- 
sponsible for  the  operation  of  converter  substa- 
tions. The  discussion  of  reactance  control  has  directed 
attention  to  the  varying  practice  of  power  companies 
in  measuring  the  converter  power-factor.     Until  a  few 


years  ago,  it  was  common  practice  to  operate  shunt- 
wound  converters  at  100  percent  power-factor,  con- 
necting the  current  and  voltage  windings  of  the  power- 
factor  meter  on  the  low  tension  side  of  the  converter 
transformers.  This  practice  favored  the  converter. 
With  the  growing  appreciation  of  the  advantages  of 
high  power-factor  on  the  line,  converters  began  to  be 
purchased  and  operated  on  the  basis  of  100  percent 
power-factor  on  the  line  side  of  the  converter  trans- 
formers. Also  with  the  increasing  size  of  units,  it  be- 
came more  and  more  difficult  to  connect  the  current 
windings  of  the  power-factor  meter  on  the  low  tension 
side  and  measurement  on  the  high  tension  side  became 
more  convenient.  Some  operating  engineers  have 
compromised,  in  the  interest  of  convenience,  on  current 
measurements  on  the  high  side  and  voltage  measure- 
ments on  the  low  side.  This  seemingly  unimportant  de- 
tail becomes  a  matter  of  considerable  consequence 
when  comparisons  are  made  between  the  case  of  a 
simple  converter  having  high  reactance  transformers 
for  voltage  control  and  a  booster  converter  with  low  re- 
actance transformers.  F.  D.  Newbury 


Generally   speaking,   no   industry  can 
Railway  continue  to  exist  if  its  revenue  does 

Utilities  not  equal  or  exceed  its  necessary  ex- 

Approaching     penditures.     That  many  of  the  utili- 
Stability  ties    have    been    attempting    an    im- 

possible feat  is  only  too  well  known 
to  those  who  have  been  in  touch  with  their  problems.  A 
year  or  more  ago  the  future  looked  almost  hopeless. 
During  1920,  however,  there  came  a  decided  improve- 
ment both  in  the  actual  conditions  of  operation  and  in 
the  attitude  of  the  public  and  of  the  regulatory  bodies. 
Mr.  P.  H.  Gadsden,  President  of  the  American  Electric 
Railway  Association,  in  reporting  on  the  electric  rail- 
way industry  for  1920,  exhibits  a  decidedly  hopeful  atti- 
tude, indicating  that  the  reports  received  show  a 
gradual  approach  to  a  stable  basis  in  that  industry. 

At  the  same  time  he  presents  a  word  of  caution. 
Many  companies,  during  the  past  few  years,  have 
strained  their  financial  resources  to  the  limit  by  merely 
keeping  their  cars  running,  and  have  not  been  able  to 
consider  proper  maintenance  of  their  properties.  Mr. 
Gadsden's  plea,  therefore,  is  that,  assuming  that  rates 
have  been  or  soon  will  be  adjusted  to  a  position  which 
will  enable  the  properties  to  avoid  receiverships,  an 
early  reduction  of  such  rates  should  neither  be  expected 
nor  advised  until  the  operating  companies  get  their 
properties  into  first-class  condition. 

While  it  will  doubtless  take  time  for  some  railways 
to  eliminate  annual  deficits  there  should  thereafter  begin 
a  period  of  rehabilitation  by  which  permanently  im- 
proved and  well-equipped  transportation  service  can  be 
supplied  to  the  American  public.  A.  H.  McIntire 


riio  J)iial  DAvo  UiUls 


IVA\  STEWART   FORDE 

Manager,  Small  Turbine  Division, 
W'cstinghousc  Electric  &  Mfg.  Company 


E 


CONOMY  is  the  watchword  of  all  the  forces  that 
have  to  do  with  the  operation  of  a  power  house, 
regardless  of  whether  this  generating  station  be 
the  workshop  of  a  large  public  utility  or  the  means  of 
providing  some  industrial  plant  with  electrical  energy. 
Economy  is  the  question  that  is  being  studied  as  never 
Ijefore  by  the  operating,  engineering  and  managerial 
elements  of  any  business  requiring  the  need  of  elec- 
trically generated  power. 

On  one  hand,  we  hear  of  boilers  being  planned  for 
500  pounds  steam  pressure,  in  order  to  eflfect  an 
economy  in  the  prime  mover;  we  know  of  refinements 
continually  being  made  in  the  prime  mover  itself  tend- 
ing towards  a  more  economical  utilization  of  the  heat  in 
the  steam,  and  of  scientifically  operated  boiler  rooms. 
On  the  other  hand,  it  is  not  generally  known  that  eco- 
nomies can  also  be  effected  in  first  and  operating  costs 
by  the  proper  selection  of  auxiliaries.  Suppose,  for  in- 
stance, a  dual  or  double  economy  could  be  obtained,  one 
that  would  be  of  importance  to  the  manager  in  first  cost, 
and  to  the  operator  in  plant  economy;  could  either  fac- 
tor in  central  station  operation  ignore  it? 

A  notable  advance  has  been  made  in  auxiliar}- 
economies  of  late,  especially  in  large  central  stations,  by 
resorting  to  what  is  known  as  a  house  turbine,  in  order 
to  reduce  the  number  of  steam  auxiliaries  in  plants 
where  the  exhaust  steam  demand  is  cared  for  in  another 
form.  This  house  turbine  is,  in  effect,  a  turbine-gen- 
erator unit  large  enough  to  supply  electric  motive  power 
for  motor  driven  auxiliary  apparatus  for  condensers, 
boiler  feed,  service  and  sump  pumps,  stoker  fans,  etc. 
In  such  installations,  the  variable  exhaust  steam  de- 
mand, if  any,  is  taken  care  of  by  the  house  turbine, 
which  is  designed  to  operate  either  as  a  non-condensing 
unit  or  under  relatively  low  vacuum. 

But  even  with  the  installation  of  a  house  turbine, 
there  are  certain  auxiliaries  for  which  it  is  desirable  to 
have  a  duplication  of  the  electric  drive  if  all  possible 
failures  are  to  be  prevented.  The  number  of  auxiliaries 
about  a  large  power  house  tlaat  require  some  form  of 
drive  presents  quite  a  formidable  problem  to  the  oper- 
ator. Some  of  tlie  more  important  auxiliaries  are: — 
Stokers 

Stoker  draft  fans 

Boiler  feed  pumps 

Condenser  pumps 

a — circulating 

b — air  pump 

c — condensate 

Service  pumps 

Exciters 

An  operator,  therefore,  has  the  big  problem  of 
keeping  the  auxiliaries  operating  continuously,  in  spite 
of  the  possible  failure  of  either  the  steam  or  electric 


drive,  without  a  sacrifice  in  plant  economy  in  doing  so. 
And  since  continuity  of  service  of  auxiliaries  is  one  of 
the  main  factors  in  keeping  the  main  units  in  operation, 
it  is  on  them  that  we  shall  dwell  in  this  article,  with  the 
suggestion  that  a  sufficient  number  of  them  be  equipped 
with  a  double  or  dual  drive. 

With  dual  drive,  the  auxiliaries  so  equipped  would 
have  a  motor  on  one  end  and  a  turbine  on  the  other, 
thus  giving  positive  assurance  that  as  long  as  there  is 
steam  in  the  boilers  and  the  driven  auxiliaries  are  in 
working  order,  it  will  be  possible  to  operate  the  boilers, 
stokers,  condenser  and  exciters  at  all  times.  Where  it 
is  undesirable  to  have  both  the  turbine  and  motor 
combination  on  a  particular  piece  of  apparatus,  a  dupli- 
cation of  the  auxiliaiy,  with  a  turbine  in  one  case  and 
a  motor  in  the  other,  is  the  proper  solution. 

As  an  illustration,  in  the  case  of  three  boiler  feed 
pumps,  and  particularly  where  there  is  a  house  turbine 


( 


FIG.    I — 300   KW   DUAL  DRIVE  EXCITER   UNIT 

During  the  past  two  years  this  unit  has  been  operating  in 
conjunction  with  a  200  kw  standard  geared  turbine  unit,  at  the 
Cleveland  Municipal  Electric  Light  Plant,  Cleveland,  Ohio. 

installed  furnishing  the  exhaust  steam,  one  of  these 
pumps  at  least  should  be  driven  by  a  steam  turbine. 
And  this  same  argument  would  hold  good  for  stoker 
fans.  On  the  condenser  pumps  in  large  stations,  par- 
ticularly with  twin  jet  condensers,  the  dual  drive  of  one 
unit  by  both  a  motor  and  steam  turbine  is  a  practical  in- 
stallation. With  large  surface  condensers,  where  tlie 
circulating,  air  and  condensate  pumps  are  separately 
driven,  the  problem  becomes  somewhat  difficult,  and  the 
local  conditions  of  space  and  pumping  arrangements 
must  be  considered. 

In  the  case  of  the  exciter,  instead  of  having  a 
separate  motor  driven  exciter  unit  and  a  separate  steam 
turbine  exciter  unit,  the  two  exciters  should  be  consoli- 
dated into  a  single  excitation  unit  of  the  dual  drive  t)T)e. 
Such  a  unit  would  then  consist  of  a  steam  turbine, 
direct-current  generator  and  alternating  current  motor. 
The  first  cost  would  naturally  be  less  than  the  corre- 
sponding cost  of  a  motor  generator  set  and  a  steam  tur- 


Februaiy,  1921 


THE  ELECTRIC  JOURNAL 


49 


bine  driven  exciter  unit,  and  hence  an  initial  or  first 
cost  economy  is  secured. 

From  an  operating  or  plant  economy  standpoint, 
the  dual  drive  unit  leaves  nothing  to  be  desired.  It  is 
a  perfect  unit  with  respect  to  the  driving  elements. 
The  turbine,  the  direct-current  generator  and  alternat- 
ing-current motor  are  all  mounted  upon  a  cast  iron 
bedplate.     The  steam  turbine  and  electric  motor  being 


FIG.   2 — 350   K\V   DUAL   riKIVF    FXCniR    I\1T 

One  of  the  three  units  to  be  installed  in  one  ot  the  Dn- 
quesne  Light  Companj-'s  stations  in  the  Pittsburgh  district. 

connected  at  their  respective  ends  to  the  generator  by 
means  of  couplings,  it  is  very  easy  to  remove  one  or  the 
other.  In  some  of  the  earlier  installations,  the  usual 
motor  generator  set  was  embodied  in  this  combination, 
with  the  turbine  coupled  to  the  motor  end.  The  idea 
was  that  it  afioi\. ,  ■^  easier  access  to  the  generator  com- 
mutator, but  in  later  installations  this  has  been  modified 
so  that  the  generator  is  the  middle  element  of  the  unit, 
thus  making  it  possible  and  practicable  to  disconnect 
either  the  turbine  or  the  motor.  This  advantage,  in  our 
opinion,  is  sufficient  to  outweigh  the  problem  of  getting 
at  the  commutator. 

In  ordinary  operation,  the  unit  consisting  of  a 
turbine,  a  generator  and  a  motor  is  in  reality  a  motor 
generator  set,  with  the  steam  turbine  acting  as  the  "in- 
surance policy"  for  continuity  of  operation.  In  a  case 
of  this  kind,  the  turbine  is  idling  (being  furnished  with 
just  sufficient  steam  to  prevent  excessive  friction  heat- 
ing), with  its  governor  so  set  that  should  the  electric 
motor  show  any  disposition  to  lower  its  speed,  the 
governor  on  the  turbine  instantly  admits  steam  to  the 
inlet  valve,  and  the  load  is  then  carried  by  the  turbine. 
This  type  of  unit  is  so  arranged  that  either  the  steam 
turbine  or  the  motor  will  individually  or  collectively 
develop  the  maximum  capacity  of  the  exciter. 

It  might  be  proper  to  answer  certain  pertinent 
questions : — 

I — In  the  event  of  an  accident  to  the  electric  motor, 
will  the  turbine  quickly  take  up  the  load?  The  turbine  will 
instantly  pick  up  the  load  and  carry  any  part  or  all  of  it. 

2 — Under  similar  circumstances,  will  the  motor  carry 
the  load  in  the  event  of  an  accident  to  the  turbine?  It  will. 
3— Can  this  combination  be  so  arranged  that  the  tur- 
bine will  carry  variable  loads  at  the  dictation  of  the  oper- 
ator; say  20  percent  at  one  time,  40  percent  at  another  and 
60  percent  at  other  times,  the  motor  pulling  the  balance?  It 
can. 


4 — Can  the  load  be  shifted  easily  from  one  driving  cle- 
ment to  the  other  without  disturbing  the  regulation  of  the 
excitation  current?    Yes. 

5 — Can  the  steam  turbine  exhaust  steam  be  used  for 
heating  incoming  feed  water?  Aside  from  the  guarantee 
of  continuity  of  excitation,  the  question  of  exhaust  steam 
demands  as  applied  to  the  dual  drive  unit  is  its  big  operat- 
ing feature.  The  idea  is  to  pass  only  suflicient  steam 
through  the  tiubine  to  supply  the  necessary  exhaust  steam 
heat  to  the  incoming  feed  water,  so  that  no  steam  is  lost  by 
exhausting  it  to  the  atmosphere,  the  remaining  load  being 
carried  by  the  motor. 

The  possible  causes  for  failure  of  the  motor  to 
function  may  be  classified  as  follows : 

a — Sudden  voltage  drop  due  to  line  trouble  would  tend 
to  lessen  its  speed. 

b — Frequency  of  the  main  unit  furnishing  power  to  the 
motor  may  drop  due  to  overloads  or  low  steam  pressure, 
causing  the  motor  to  slow  down. 

c — Possible  burn  out  of  motor. 

It  is  during  such  periods  as  these  that  the  steam 
turbine  not  only  acts  as  a  "capacity  puller"  but  a  direct- 
current  voltage  regulator  as  well.  It  will  therefore  be 
seen  that  such  a  unit  is  very  elastic  when  viewed  from 
an  operation  standpoint. 

The  question  of  the  economy  of  such  a  unit  with 
reference  to  power  house  economy  may  rightfully  come 
u])  at  this  time.  No  power  house  wants  to  waste  a 
single  pound  of  steam  by  exhausting  it  to  the  atmos- 
phere. The  ideal  way  is  to  utilize  all  exhaust  steaux 
A  central  station  should  produce  sufficient  exhaust 
steam  to  create  a  heat  balance  only.  That  is,  any  well 
conducted  power  house  will  have  only  enough  con- 
tinually operated  steam  auxiliaries  to  produce  the  re- 
quisite amount  of  exhaust  steain  to  heat  the  incoming 
feed  water  up  to  the  ideal  temperature,  leaving  aside, 
of  course,  the  fact  that  many  engineers  have  a  natural 
perference  for  keeping  their  auxiliaries  independent  of 
the  generating  units,  figuring  that  as  long  as  they  have 
steam  in  their  boilers  they  will,  at  least,  be  assured  of 


I'IC.    3 — 50   KW   DU.'\L  DRIVE  EXCITER   UNIT  FOR  THE   MERIDEN'   ELEC- 
TRIC LIGHT  COMP.ANY,    MERIDEN,   CONN. 

I^oad  on  this  turbine  can  be  varied  to  meet  the  exhaust 
steam  demand  while  the  unit  is  in  operation. 

auxiliary  power.  But  the  cost  of  fuel  has  even  com- 
pelled many  operators  who  favor  this  scheme  to  reduce 
it  to  a  minimum,  particularly  where  there  is  a  surplus 
of  exhaust  steam. 

In  the  case  of  the  dual  drive  unit,  either  on  pumps, 
fans  or  exciters,  the  steam  consumption  can  be  adjusted 
so  that  it  is  unnecessan'  to  generate  more  steam  than 


50 


THE  ELECTRIC  JOURNAL 


\o\.  XVIII,  No.  2 


is  needed  in  the  system.  This  is  accomplished  by  mak- 
ing the  electric  motor  carry  the  major  portion  of  the 
load  and  the  steam  turbine  the  remainder  up  to  the 
point  of  taking  care  of  the  heat  balance  or  exhaust 
steam  demand,  it  being  possible  to  vary  the  load  on  the 
turbine  from  zero  to  maximum  while  the  unit  is  in  op>- 
eration  without  in  any  way  interfering  with  the  opera- 
tion of  the  motor  other  than  reducing  the  motor  load. 

With  the  steam  turbine  large  enough  to  handle  the 
maximum  load  requirement,  and  its  governing  mechan- 
ism so  set  as  to  vary  the  capacity  it  should  develop,  de- 
pending on  the  demand  for  heat,  it  will  be  seen  that  the 
question  of  its  steam  consumption  rate  does  not  inter- 
fere in  any  way  with  the  endeavors  of  the  operators  to 
maintain  a  perfect  heat  balance. 

The  question  of  unit  economy  with  respect  to  plant 
economy  has  been  worked  out  by  arranging  the  dual 
drive  units  with  either  direct  connected  or  geared  tur- 
bines for  the  steam  drive.  The  direct-current  genera- 
tor must,  of  necessity,  be  of  relatively  low  speed.  That 
means  that  the  steam  turbine  driving  it,  if  direct  con- 
nected, must  also  be  of  the  same  speed.  Slow  speeds 
however,  tend  to  lower  the  efficiency  of  the  turbine, 
with  the  result  that  from  a  unit  standpoint,  the  effi- 
ciency of  the  direct-connected  set  would  not  be  as  good 
as  though  a  moderately  high-speed  turbine  and  gear 
were  used  for  driving  the  generator. 

Direct-connected  units  are  installed  where  the  pur- 
chaser has  a  preference  for  this  type;  where  the  steam 
turbine  will  only  be  used  as  a  stand-by,  or  for  variable 
or  moderate  amounts  of  steam.  Some  central  stations, 
however,  prefer  a  dual  drive  unit  with  geared  turbine 
drive  that  might  never  in  normal  circumstances  furnish 
more  than  a  minimum  amount  of  exhaust  steam  for 
heating  purposes,  because  they  feel  that  there  might  be 
times  when  the  entire  load  would  have  to  be  carried  by 
the  tutbine.  In  this  case,  the  question  of  unit  steam 
consumption  becomes  of  paramount  importance.  This 
combination  would  obviously  be  more  econmical  than 
the  direct-connected  set  and  would,  if  operated  only  for 
a  short  period,  more  than  justify  the  additional  cost  of 
the  reduction  gear. 

The  two  combinations  of  dual  drive  unit  will 
always  have  their  respective  fields  and  partisans,  and 
the  particular  installation  of  one  or  the  other  will  be 
governed  by  the  exhaust  steam  requirements,  available 
space,  the  likelihood  of  continuous  turbine  operation, 
first  cost  and  the  preference  of  the  operator  for  one  or 
the  other.  The  majority  of  small  and  medium  capacity 
dual  drive  units  have  up  to  this  time  been  of  the  direct- 
connected  type,  but  in  capacities  of  300  kilowatts  and 
larger  the  geared  unit  is  undoubtedly  the  better  and 
more  economical  installation,  particularly  where  the 
steam  turbine  will  always  be  operated  under  load. 
Where  no  steam  is  required  from  the  turbine  in  these 
large  sizes,  space  and  first  cost  will  enter  into  the  selec- 
tion. 


So  far  as  the  electric  motor  is  concerned,  there  is 
also  the  choice  of  two  methods  of  drive,  namely,  an 
induction  motor  or  a  synchronous  motor.  The  operat- 
ing preference  is  for  the  induction  type  because  it  is 
somewhat  simpler  than  the  synchronous  type,  which  re- 
quires the  complication  of  direct-current  excitation. 
Moreover,  the  synchronous  motor  will  have  a  greater 
tendency  to  pull  out  if  there  is  a  drop  in  voltage.  The 
induction  motor  will  drop  in  speed  under  such  condi- 
tions and  ease  off  its  load,  while  the  synchronous  motor 
will  maintain  the  same  speed  and  hold  on  to  its  load,  so 
that  even  with  the  same  pull  out  torque  the  induction 
motor  has  better  operating  characteristics  for  a  dual 
drive  unit,  with  the  steam  turbine  arranged  for  load 
carrying  with  any  slowing  down  in  the  induction  motor, 
to  say  nothing  of  the  advantage  of  eliminating  the  nec- 
essary excitation  on  the  synchronous  tj'pe. 

Units  of  the  dual  drive  type  are  not  passing 
through  the  experimental  stage,  for  they  have  been  in 
successful  commercial  power  house  operation  for 
several  years.      The  capacities  of  these  combinations 


\ 


FIG.   4—200     KW     CE.\REn     PIAI.     DRIVE     IXIT     OPER.\TING     I.N     THE 
PLANT  OF  THE   NARRAG.\NSETTE  ELECTRIC   LIGHT   COMPANY 

This  unit  is  equipped  with  a  special  device,  on  the  steam 
end,  for  varying  the  load  on  the  steam  turbine. 

var}-  from  15  up  to  500  kilowatts.  A  500  kilowatt  unit, 
the  largest  size  yet  contracted  for  to  our  knowledge, 
will  be  installed  in  the  plant  of  the  Narragansett  Elec- 
tric Lighting  Company,  Providence,  R.  I.  It  will  be 
of  the  geared  type  and  will  be  a  companion  unit  to  a 
200  Kilowatt  geared  dual  drive  unit  now  installed  in 
the  same  station.  The  200  kilowatt  unit  has  been 
operated  in  parallel  with  a  300  Kilowatt  geared  steam 
turbine  exciter  set  previously  installed.  It  is  interestmg 
;o  note  however  that  three  350  kw  dual  drive  direct-con- 
nected units  will  be  installed  in  one  of  the  power  sta- 
tions of  the  Duquesne  Light  Company,  of  Pittsburgh. 

An  interesting  feature  in  connection  with  this  line 
of  dual  drive  units  is  that  the  steam  turbines  are  de- 
signed primarily  for  installation  in  central  stations  hav- 
ing high  steam  pressures  and  high  superheat,  resulting 
in  extremely  high  total  temperatures.  The  steam  tur- 
bines are  provided  with  center  line  supports  which  per- 
mit expansion  of  the  cylinder  without  causing  align- 
ment difficulties. 


Coiiiiiuaaior 


R.  II.  XliU  TON 

Power  Engineering  Dopt., 
k\'cstinghousc  Electric  &  Mfg.  Co. 


j]cni\ojU){(S 


THE  selection  of  suitable  brushes  for  commutator 
use  involves  both  electrical  and  mechanical  con- 
siderations, depending  upon  the  characteristics 
of  the  machine  in  question.  From  the  electrical  stand- 
point, any  brush,  to  be  suitable,  must  have  proper  con- 
tact drop  to  keep  the  'short-circuit  currents  under  the 
brush  w^ell  within  control  with  a  minimum  brush  PR 
loss,  when  the  machine  is  operating  under  normal  con- 
ditions; and,  in  addition  to  this,  must  also  have  suffi- 
cient current  carrying  qualities  to  prevent  overheating. 
From  the  mechanical  standpoint,  the  peripheral  speed 
of  the  commutator,  angle  of  the  brushholder,  and 
whether  commutator  mica  is  undercut  or  not,  are  all  im- 
portant factors  to  consider  in  the  selection  of  a  brush 
with  proper  characteristics  to  give  long  brush  life  with 
low  friction  losses  and,  at  the  same  time,  ride  smoothly 
on  the  commutator  so  as  to  give  the  minimum  amount 
of  noise  and  vibration.  These  electrical  and  mechanical 
characteristics  must  all  be  given  consideration  in  the 
selection  of  brushes  for  any  given  machine,  if  best 
commutation  and  all  around  satisfactory  operation  is  to 
be  obtained  with  a  minimum  amount  of  maintenance 
and  upkeep  expense. 

The  service  required  of  a  machine  is  another  im- 
portant factor  in  deciding  the  proper  grade  of  brush  to 
select.  For  instance,  railway  service  with  a  load  factor 
of  65  percent  during  12  daylight  hours  and  20  percent 
during  12  hours  night  service,  will  obviously  permit 
greater  latitude  in  brush  application  for  a  given  ma- 
chine, than  where  the  same  machine  is  applied  to  elec- 
trolytic service  with  a  98  percent  load  factor  over  the 
entire  24  hours  of  the  day. 

While  it  must  be  understood  that  every  application 
of  brushes  for  commutator  use  should  be  decided  only 
after  consideration  of  all  the  merits  and  characteristics 
involved  in  each  individual  case,  the  following  tabula- 
tion will  be  found  useful  as  a  reference  in  approxi- 
mating most  of  the  average  cases: — 

Carbon  Graphite  Brushes  are  suitable  for  use  on  non- 
undercut  commutators,  with  commutator  speeds  up  to  3000 
feet  per  minute,  and  brush  densities  not  exceeding  35  am- 
peres per  square  inch.  This  grade  of  material  inckides  all 
brushes  commonly  called  carbon  brushes.  They  arc  com- 
posed chiefly  of  amorphous  carbon  or  coke  with  only 
enough  graphite  added  to  give  the  brushes  slight  lubricat- 
ing qualities. 

Graphitised  Carbon  Brushes  are  adapted  for  use  on 
undercut  commutators  with  commutator  speeds  up  to  4500 
feet  per  minute,  and  brush  densities  not  exceeding  50  am- 
peres per  square  inch.  On  apparatus  in  railway  service, 
with  the  usual  load  factors,  this  grade  of  brush  is  appli- 
cable on  commutator  speeds  up  to  5500  feet  per  minute 
and  densities  of  55  amperes  per  square  inch.  This  grade 
of  material  includes  brushes  which  contain  considerable 
graphite   in   their  composition   with  the  balance   of   amor- 


phous carbon  or  coke.  This  class  of  material  usually  has 
a  tinal  baking  operation  carried  to  a  high  temperature, 
which  results  in  moditication  of  the  material,  leaving  most 
of  it  in  the  form  of  graphite. 

Graphite  Brushes  arc  good  for  use  only  on  undercut 
commutators  with  commutator  speeds  up  to  6000  feet  per 
minute,  and  brush  densities  for  all  classes  of  service  at 
heavy  load  factors  and  densities  of  60  and  65  amperes  per 
square  inch.  This  grade  of  material  is  composed  almost 
entirely  of  graphite  except  for  a  little  copper  in  some  cases, 
and  the  binding  material  necessary  to  hold  the  particles  of 
graphite  together. 

Generally  speaking,  the  hard  or  carbon  brushes 
have  abrasive  or  scouring  action  on  commutators, 
while  the  softer  graphite  grades  lubricate  and  give  the 
coinmutator  a  good  polish.  It  has  been  found,  how- 
ever, that  graphite  brushes  often  cause  bad  grooving 
of  the  commutator,  and  when  replaced  by  a  harder 
brush  of  the  graphitized  carbon  grade  this  grooving 
would  practically  disappear.  This  has  been  found  to 
be  the  case  more  particularly  on  older  machines  where 
the  direct-current  brushes  were  staggered  alternately, 
and  the  most  feasible  explanation  seems  to  be  that  a 
minute  arcing  action  takes  place  under  the  face  of  the 

fe'?^".'^  ^/^^^J  ^//^./^ 


V'/^'>'zl  \/^///A  V//////t 

FIG.    I — INCORRECT  ^:ETH0D  OF 
ST.A.GGERING  BRUSHES 


Rs^'y"'"^    kssNsX'^    Rxwws^ 

fe";r/-.^  \.,.A  "^//y^A 

Kssx*-!''?]    K^wxsxN    UxssWN 

FIG.     2 — CORRECT      METHOD    0" 

ST.\GGERING  BRUSHES 


positive  (current  leaving  commutator  and  flowing  into 
brushes)  brushes,  which  burns  away  the  copper  and 
causes  it  to  be  carried  across  from  the  commutator  to 
the  brush.  Small  particles  of  copper  imbedded  in  the 
face  of  the  brushes  will  often  be  found  as  evidence  of 
this  action  if  examination  of  the  brushes  is  made. 

The  incorrect  method  of  staggering  brushes  is 
shown  in  Fig.  i.  It  will  be  seen  from  this  sketch  that 
any  action  peculiar  to  either  polarity  is  cumulative 
when  all  brushes  of  each  polarity  are  in  the  same  path 
entirely  around  the  commutator. 

The  correct  method  of  stagger  is  shown  in  Fig.  2. 
With  this  arrangement,  any  action  tending  to  take  place 
under  brushes  of  one  polarity  will  be  neutralized,  in  a 
way,  by  the  brushes  of  opposite  polarity  being  directly 
in  line  with  them.  This  arrangement  gives  a  more  uni- 
form wear  over  the  entire  face  of  the  commutator,  and 
thus  permits  the  satisfactory  operation  of  certain 
grades  of  brushes  where  grooving  trouble  may  have 
been  experienced  with  the  incorrect  scheme  of  stagger- 
ing. 


52 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


As  the  progress  in  design  of  commutating  machines 
during  the  past  few  years  has  tended  steadily  toward 
higher  speeds,  superior  composition  in  brushes  has  been 
required,  and  the  maintenance  cost  of  the  apparatus  has 
obviously  come  to  be  an  item  of  more  consequence  than 
was  the  case  with  the  older,  slower  speed,  heavier  (lbs. 
per  kw)  machines.  It  has  occasionally  been  found  that 
although  sparkless  commutation  has  been  obtained  by 
the  use  of  some  particular  high-grade  graphite  brush, 
objection  has  been  raised  to  excessive  maintenance 
costs  involved,  due  to  the  cost  of  the  brushes  them- 
selves, and  the  frequent  renewals  required,  unless  the 
commutator  was  kept  in  exceptionally  good  condition. 
In  several  cases  of  this  kind  substitution  of  a  harder 
graphitized  carbon  brush  has  been  made  and  excep- 
tionally     satisfactory      results      obtained.       Although 


usually  a  change  of  this  kind  is  accompanied  by  some 
slight  pin  sparking,  many  operators  feel  that  a  com- 
promise involving  only  a  slight  sacrifice  in  the  commu- 
tating performance  of  their  apparatus  is  warranted 
when  maintenance  costs  can  be  so  materially  reduced. 
In  cases  where  serious  commutation  trouble  is  be- 
ing experienced,  an  inspection  of  the  apparatus  is  al- 
ways desirable  in  order  that  a  thorough  analysis  of  all 
conditions  pertaining  to  the  operation  and  service  may 
be  made.  In  cases  where  trouble  is  inherent  with  the 
brushes  alone,  and  recommendation  for  a  change  in 
grade  seems  to  be  necessar>',  the  brush  manufacturers 
retain  a  staff  of  capable  representatives  whose  services 
are  always  available  upon  request  in  all  matters  pertain- 
ing to  brush  applications. 


F.  T.  HAGUE 


THE  INTRODUCTION  of  the  synchronous  con- 
verter as  a  source  of  power  supply  for  railway 
and  industrial  loads  early  developed  the  necessity 
of  some  form  of  voltage  control  of  wider  range  than 
that  which  is  inherent  in  the  converter  itself.  In  the 
early  90's  the  power  supply  units  were  of  small  ca- 
pacity, as  also  were  the  industrial  loads,  permitting  a 
concentration  of  power  consumption  close  to  the  source 
of  power  supply.  The  railway  systems  naturally  re- 
quired the  distribution  of  power  over  long  distances 
but,  fortunately  from  one  point  of  view,  the  difficulties 
incident  to  keeping  railway  systems  running  at  all  were, 
by  comparison,  of  such  magnitude  that  voltage  regula- 
tion of  the  power  source  was  a  matter  of  relatively 
small  importance. 

Steadily  continued  growth  of  industrial  loads,  both 
in  the  power  consumption  per  unit  and  the  distribution 
over  a  greater  area,  was  accompanied  by  the  develop- 
ment of  larger  power  supply  units  and  larger  central 
stations.  Combined  with  this  tendency,  the  rapid  de- 
velopment in  reliability  of  operation  of  railway  systems 
forced  an  early  consideration  of  the  problems  of  power 
distribution  and  voltage  regulation  when  synchronous 
converters  were  used.  Economy  of  operation  and  re- 
liability of  service  favored  the  development  of  large 
distributing  stations,  and  this  development  further 
served  to  accentuate  the  inherent  defects  of  absence  of 
voltage  control  of  synchronous  converters  in  sen'ice 
where  some  voltage  control  was  required. 

Chas.  F.  Scott,  in  ICS93,  proposed  the  first  form 
of  the  now  well  known  booster-type  converter. 
(Pat.  515885),  consisting  of  a  simple  converter  con- 
nected in  series  on  its  alternating-current  side  with  a 
small  alternating-current  booster  mounted  on  the  con- 


verter shaft.  His  object  was  limited  to  the  mainten- 
ance of  constant  direct-current  potential  or  compound- 
ing proportional  with  the  direct-current  load  and  was 
accomplished  by  connecting  the  field  winding  of  the 
alternating-current  booster  in  series  with  the  converter 
direct-current  load  circuit.  Although  among  the  first 
to  be  conceived,  this  type  of  machine  lay  dormant  until 
the  electrical  industrj^  developed  to  a  point  where  its  re- 
vival, with  slight  modification,  became  a  necessity  for 
the  proper  and  efficient  control  of  voltage  of  converters 
supplying  industrial  networks. 

Three  years  later,  in  1896,  the  fundamental  prin- 
ciple that  an  out-of-phase,  or  wattless  current  flowing 
through  a  reactance  would  induce  an  in-phase  voltage 
was  commercially  introduced  into  synchronous  con- 
verter distribution  systems  by  R.  D.  Mershon  and 
B.  G.  Lamme.  (Pats.  571836  and  571863)  Their  sys- 
tems differed  only  in  detail,  Mr.  Lamme  using  the  inher- 
ent reactance  in  the  alternating-current  distribution  cir- 
cuits while  Mr.  Mershon  covered  the  insertion  of  separ- 
ate external  reactance.  While  the  initial  object  was  to 
provide  automatic  regulation,  whereby  the  voltage  de- 
livered to  the  direct-current  circuit  would  be  auto- 
matically adjusted  in  accordance  with  the  changes  in 
direct-current  load,  it  was  later  enlarged  by  Mershon 
(Pat.  620343")  to  provide  means  whereby  the  voltage 
delivered  to  the  direct-current  circuit  might  be  adjusted 
in  accordance  with  the  requirements  of  the  load.  From 
patent  interferences,  it  also  developed  that  Dr.  C.  P. 
Steinmetz  had  independently  proposed  somewhat  simi- 
lar arrangements.  This  appears  to  have  been  the 
inception  of  a  system  of  electrical  distribution  still  used 
on  most  railway  converters,  comprising  an  alternating- 
current  supply  containing  reactance  and  a  svnchronous 


February,   1921 


THE   ELECTRIC  JOURNAL 


53 


converter  provided  with  means  for  varying  the  ampere- 
turns  of  its  shunt  or  compound  fields  in  order  to  vary 
the  voltage  at  the  direct-current  terminals.  It  is  inter- 
esting to  note  that  the  disproportionate  increase  of 
armature  coil  heating  caused  by  wattless  currents  was 
not  taken  into  account  until  some  time  after  this  sys- 
tem was  conceived. 

While  the  reactance  controlled  converter  was  im- 
mediately destined  to  take  a  leading  part  in  railway 
power  su[i[)ly,  there  were  certain  conditions  which  pre- 
vented it  from  fulfilling  all  of  the  requirements  of  in- 
dustrial and  lighting  service.  The  railway  units  oper- 
ated over  a  desirable  range  of  power-factor,  from  lag- 
ging at  light  load  to  leading  at  overloads  and  the  in- 
creased armature  coil  heating  and  average  efficiency 
over  the  ragged  load  cycle  met  in  railway  work,  were 
reasonable  and  satisfactory.  The  liberal  thermal  ca- 
pacity of  the  low-speed  converters  of  this  period  made 
them   relatively  unaffected  by  the   increased  armature 


this  type  unit  from  persisting. 

For  industrial  work,  the  variable  voltage  trans-' 
former,  typified  by  the  induction  regulator,  came  into 
vogue  in  1897  and  continued  until  about  1904.  It  em- 
bodied many  desirable  characteristics,  chief  among 
them  being  wide  voltage  range,  good  efficiency  and  the 
use  of  a  standard  type  converter  free  from  the  addi- 
tional heating  of  wattless  currents.  Its  defects  arose 
chiefly  from  the  cost  of  the  regulator  when  built  for 
large  size  units,  and  the  introduction  of  an  additional 
];iece  of  apparatus  taking  up  valuable  floor  space.  A 
large  number  of  non-commutating  pole  converters  for 
use  with  induction  regulators  have  been  built  and  are 
si  ill  being  operated  successfully,  although  in  many  of 
tlie  larger  systems  they  are  being  replaced  by  larger  ca- 
pacity, higher  speed  booster  converter  units  of  more 
modern  design  which  occupy  the  same  floor  space. 

L'ntil  1899  all  voltage  control  systems  for  syn- 
chronous converters  functioned  by  employing  external 


FTG,    I — 4000    K\V,   275    VOLT, 

One  of  10  diinlicatc  units  built 

heating  caused  by  wattless  currents  when  operating  on 
a  typical  railway  load  cycle  consisting  of  intermittent 
peak  loads.  The  industrial  units  were  ordinarily  of 
much  larger  size  and  in  many  cases  required  a  wider 
range  of  voltage  than  the  railway  units.  The  load 
cj'cle  was,  moreover,  much  more  nearly  constant,  and 
there  was  no  generally  desirable  relationship  between 
the  converter  power-factor  and  the  amount  of  load,  so 
that  armature  heating  due  to  wattless  currents  became 
a  serious  problem  and  the  total  efficiency  was  not  all 
that  could  be  desired.  About  1897  the  British  Thomp- 
son-Houston Company  brought  out  a  wide  range  re- 
actance controlled  converter,  wherein  wide  range  was 
obtained  by  means  of  high  external  reactance  and  cor- 
respondingly small  wattless  current  in  the  converter 
armature.  Other  operating  characteristics,  such  as 
low  power-factor  of  converter  and  transformer  as  a 
unit,  poor  stability  and  efficiency,  combined  to  prevent 


167   R.P.M.    BOOSTER   CONVERTER 

for  the  New  York  I''disop  Co. 

means  to  control  the  magnitude  of  the  alternating-cur- 
rent voltage  impressed  on  the  converter  rings,  either  by 
voltage  generated  in  an  external  booster  or  voltage  in- 
duced in  a  reactance  coil  by  out-of-phase  currents.  At 
this  time  a  new  type  of  converter  was  proposed  by  Mr. 
Woodbridge,  (Pat.  679812)  afterwards  termed  the 
"split-pole"  converter,  in  which  the  direct-current  volt- 
age could  be  regulated  with  the  alternating-current 
supply  voltage  held  constant.  This  was  accomplished 
by  splitting  the  main  pole  pieces  into  three  sections, 
each  section  being  controlled  by  an  independent  field 
coil  wound  around  it,  thereby  allowing  any  desired  dis- 
tribution of  the  lines  of  magnetic  force  over  the  pole 
faces  to  be  obtained.  Thus  by  concentrating  the  lines 
of  force  near  the  middle  of  the  pole  face,  they  become 
more  effective  in  producing  alternating  voltage  and  the 
ratio  of  alternating  to  direct-current  voltage  is  in- 
creased,  since  the  direct-current  voltage  is  dependent 


54 


THE  ELECTRIC  JOURNAL 


Vol.  X\1II,  No.  2 


only  on  the  quantity  and  not  the  distribution  of  the  lines 
of  force.  Conversely  by  concentrating  the  field  flux  at 
the  tips  of  the  main  poles,  the  ratio  of  alternating  to 
direct-current  voltage  is  reduced.  The  advantages 
claimed  for  this  system  over  the  reactance  control  sys- 
tem were  improvement  in  armature  heating,  power-fac- 
tor, efficiency  and  regulation  of  the  alternating-current 
apparatus  and  transmission  lines,  as  well  as  greater 
stability  of  the  converter  itself  due  to  the  absence  of 
wattless  currents. 

It  was  not  until  about  1904  that  the  split-pole  con- 
verter was  introduced  commercially  in  industrial  serv- 
ice. As  a  competitor  of  the  then  existing  types  of 
converters  it  embodied  certain  advantages  but  it 
possessed  inherent  commutating  defects  which  caused 
it  to  become  obsolete  within  a  few  years.  Non-commu- 
tating  pole  converters  require  a  commutating  field  or 
"fringe"  from  the  main  field  poles  in  order  to  commu- 
tate  successfully  and  tJie  principle  on  which  the  split 
pole  converter  operated  made  this  a  difficult  condition 
to  maintain. 

A  modification  of  the  original  booster  type  con- 
verter was  introduced  by  the  British  W'estinghouse 
Company  in  1904  and  was  being  built  in  this  country 
by  1906.  It  consisted  of  a  small  alternating-current 
generator,  usually  of  15  percent  of  the  converter  rat- 
ing, connected  in  series  with  the  alternating-current  side 
of  the  converter  and  having  its  field  excitation  so  con- 
trolled as  to  permit  any  desired  variation  of  direct-cur- 
rent voltage  independent  of  the  direct-current  load. 
The  converter  armature  was  free  from  wattless  cur- 
rents over  its  entire  voltage  range,  and  the  power-factor 
could  be  maintained  at  unity  at  all  times.  From  the 
commutation  standpoint  the  booster  type  non-commu- 
tating  pole  unit  had  no  inherent  defects,  and  in  general 
proved  a  very  popular  and  widely  used  type  of  ma- 
chine, many  units  still  being  used  successfully  in  com- 
mercial lighting  service. 

Between  1906  and  191 1  the  split-pole  and  booster 
type  converters  were  competitors  for  industrial  power 
supply,  when  the  adaptation  of  commutating  poles  in 
converter  design  about  191 1  settled  the  question  of 
their  relative  merits.  Owing  to  the  complicated  mag- 
netic structure  of  the  split-pole  converter  it  is  not  prac- 
ticable to  make  an  ideal  application  of  commutating 
poles  that  are  inherently  self-adjusting,  while  with  the 
booster  type  converter  the  addition  of  commutating 
poles  presents  no  theoretical  difficulties  and  relatively 
little  complication.  Coincident  with  the  introduction 
of  commutating  poles,  the  speeds  of  converters  were 
greatly  increased,  resulting  in  a  reduction  in  cost  and 
fioor  space  and  at  the  same  time  greatly  improving  the 
commutating  characteristics.  The  facility  with  which 
the  booster-type  machine  lent  itself  to  the  incorporation 
of  these  new  developments  accounts  for  its  survival 
over  other  types  possessing  less  flexibility. 

The  booster-type   converter  has   successfully  met 


all  of  the  operating  requirements  of  the  three-wire  Edi- 
son service ;  its  operating  voltage  range  has  usually  been 
considerably  in  excess  of  the  normal  service  require- 
ments, allowing  a  conservative  margin  for  unusual  op- 
crating  or  power  supply  conditions;  its  record  for  con- 
sistent, safe  operation  and  entire  freedom  from  coil 
burn-outs  has  been  due  to  the  relatively  equal  distribu- 
tion of  its  armature  copper  losses  when  working  at  its- 
extreme  limits  of  voltage  range ;  its  total  efficiency,  con- 
sidering the  losses  in  the  converter,  transformer,  trans- 
mission line  and  generating  apparatus,  is  equal  to  if 
not  better  than  that  of  any  system  requiring  large  watt- 
less currents  from  the  high-tension  line  to  accomplish 
its  voltage  control ;  its  characteristic  of  operating  at  all 
loads  and  all  voltages  at  100  percent  power-factor  on 
the  high-tension  line  makes  it  a  most  desirable  central 
station  load,  especially  when  a  premium  is  frequently 
offered  for  loads  of  high  or  leading  power-factor  char- 
acteristics; its  extreme  flexibility  in  having  its  power- 
factor  control  independent  of  the  load  and  voltage  con- 
trol, and  the  facility  and  absolute  safety  with  which  the 
converter  may  be  direct-current  started  and  synchron- 
ized onto  the  alternating-current  line  without  any 
momentary  surge  of  current  at  time  of  switching  onto 
the  line,  regardless  of  the  value  of  the  direct-current 
voltage;  all  of  these  and  possibly  many  minor  charac- 
teristics are  tangible  assets  of  the  booster  type  converter 
that  are  responsible  for  the  safe  and  consistently  satis- 
factor}'  record  of  service  that  this  type  of  machine  has 
given  since  its  introduction. 

Continued  concentration  of  power  consumption  in 
the  large  industrial  centers  has  brought  about  a  condi- 
tion analogous  to  that  pertaining  at  the  time  the  elec- 
trical industry  was  first  established.  On  many  Edison 
systems  there  is  a  certain  constant  magnitude  of  power 
demand,  located  adjacent  to  the  central  power  distribut- 
ing stations  which  may  be  supplied  with  power 
from  a  central  station  bus  having  but  a  relatively 
small  variation  in  potential  over  the  entire  day. 
Most  large  Edison  systems  maintain  three  direct-cur- 
rent voltage  busses  fed  by  converters,  all  of  which  have 
the  same  alternating-current  voltage.  At  times  of  light 
load  the  three  busses  are  close  together  in  voltage, 
while  at  times  of  heavy  load  the  bus  voltages  var}' 
widely,  depending  on  the  requirements  of  the  loads  on 
each  circuit.  This  condition  has  required  the  operation 
of  some  converters  always  bucking  the  direct-current 
voltage,  some  bucking  or  boosting  a  slight  amount  and 
some  always  boosting. 

In  the  last  few  years  some  consideration  has  been 
given  to  the  possibility  of  supplying  that  portion  of  the 
central  station  load  which  normally  requires  only  a 
small  range  of  voltage  control,  from  single  converters, 
obtaining  the  small  required  voltage  range  by  reactance 
control  with  wattless  currents.  The  advantages  to  be 
obtained  are  reduced  first  cost  of  the  converter,  a  sav- 
ing in  floor  space  which  is  frequently  important,  and  a 


Februarv',  1921 


THE  ELECTRIC  JOURNAL 


55 


simplification  of  the  converter  itself  due  to  the  omission 
of  its  booster  and  its  control.  The  reactance  con- 
trolled type  converter  has  some  operating  characteris- 
tics of  a  radically  different  nature  from  those  of  the 
booster  type  machine  and  a  discussion  of  these  features 
may  be  of  interest : — 

Method  of  Obtaining  Voltage  Range — Speaking  in 
general  terms,  a  converter  which  has  a  full  load  and  a 

TABLE  I — REACTANCE  CONTROLLED  CONVERTER 


T-T,si.,t,ne,-           Cooverter  Arm. 
l.aii.ioimei                  Wattless 

H.  T. 

Line  Wattless  Kv-a. 

Mag. 

React. 
Kv-a. 

Boost          Buck 

5S    Boost 

Mid. 
Vollase 

5S  Bucl<. 

5% 
5% 

16.6%  30%  Lead|30%  Lag 
33%     [15%  Lead|15%  Lag 

8.4%  Lead 
23%  Lag 

1                       i 

|21.6%  Lag;31.6%  Lag 

1    38%  Lagl    53%  Lag 

two  hour  50  percent  overload  rating  may  ordinarily  be 
operated  safely  with  at  least  30  percent  leading  or  lag- 
ging wattless  current  at  full  load,  as  under  these  condi- 
tions the  average  annature  heating  is  increased  30  per- 
cent and  the  tap  coil  heating  is  increased  80  percent. 
Any  voltage  range  desired  may  then  be  obtained  at  full 
load  by  using  a  reactance  of  the  proper  magnitude  in 

the  alternating-current  circuit,  since  the  avail- 

able  voltage  range  is  the  product  of  the  per- 
cent reactance  times  the  percent  wattless  cur- 
rent in  converter  armature.  With  30  percent 
wattless  k\^-a.  a  voltage  range  of  five  percent 
up  and  down  requires  a  16.6  percent  react- 
ance while  a  7.5  percent  voltage  range  re- 
quires 25  percent  reactance. 

Limits  of  Voltage  Range — The  factors 
which  limit  the  voltage  range  are  (i)  the 
maximum  amount  of  wattless  current  it  is 
safe  to  carry  in  the  converter  armature,  from 
the  heating  standpoint  of  both  armature  and 
field  windings,  and  (2)  the  reactance  avail- 
able. Having  settled  on  a  safe  maximum 
percent  wattless  W-a.  for  a  given  converter 
armature,  the  voltage  range  at  any  con- 
stant load  is  limited  only  by  the  percent  react- 
ance installed  and  the  quantity  of  wattless  kv-a.  it 
is  desirable  to  draw  from  the  high-tension  line — 
by  the  ability  of  the  generators,  lines  and  trans- 
formers to  carry  additional  current  represented  by  the 
low  lagging  power- factor.  For  any  given  volt- 
age range  the  converter  armature  may  be  favored 
by    using    a     small     wattless     current    and    a    hi^h 

TABLE  II— BOOSTER  CONVERTER 


ance,  thereby  requiring  a  smaller  wattless  kv-a.  from 
the  high-tension  line.  These  two  conditions  may 
readily  be  illustrated  by  Table  I,  where  a  five  percent  up 
and  down  voltage  range  is  required.  The  booster 
t3'pe  converter  which  normally  is  supplied  from 
a  five  percent  reactance  transformer  and  is  guar- 
anteed for  100  percent  power-factor  on  the  high-tension 
side  works  under  the  corresponding  conditions  given  in 
Table  II. 

The  High-tension  Line  Power-Factor  Charac- 
teristics— From  the  foregoing  it  is  evident  that  the 
simple  non-booster  converter  works  over  its  voltage 
range  by  requiring  a  large  range  of  wattless  kv-a.  from 
the  high-tension  line  as  a  fundamental  condition.  Fig. 
2  shows  the  high-tension  line  wattless  kv-a.  on  a  4000 
kw  converter  for  an  assumed  voltage  range  of  270  to 
290  volts,  using  a  reactance  of  20  percent  and  a  mid 
voltage  of  285  volts.  Fig.  3  shows  the  high-tension 
line  wattless  kv-a.  for  the  same  voltage  range,  270  to 
290  volts,  with  280  volts  mid  voltage  and  with  a  12.5 
percent  reactance.  These  two  conditions  are  shown  to 
illustrate  the  variation  in  high-tension  line  power-factor 


1^ 

~ 

n 

y 

■s 

^'     ■      • 

§ 

y 

y^ 

■i 

^ 

^ 

, 

i 

y 

y 

^ 

-ISM 

r»3- 

^ 

^ 

^ 

\ 

y 

I 

' 

D)  «t  qurref^\  Vol|«c«    1 

"  1 

TraTisformer 

Convener  .\rm. 
Wattle-is 

H.T.  Line  Wattless  Kv-a 

Mag.    React. 
Kv-a.    Kv-a. 

Boost            Buck 

5";    Boost       Voltage        SSI  Buck. 

5% 

5% 

10%  Lead 

10%  Lead]            0% 

0% 

0% 

transformer  reactance  resulting  in  a  large  total  wattless 
kv-a.  in  the  high-tension  line,  or  the  high-tension  line 
may  be  favored  by  drawing  a  large  wattless  current 
into  the  converter    armature  and  using  a  small    react- 


FIGS.  2  AND  3— CHARACTERISTICS  OF  4CKX)  KW  NON-BOOSTER  CONVERTER  TR.\NS- 
FOR.MER   UNIT 

Fig.  2 — 20  percent  reactance,  5  percent  magnetizing.  4  percent  in- 
ternal converter  drop,  and  3  percent  transformer  regulation.  Fig.  3 — 
12.5  percent  reactance,  5  percent  magnetizing,  4  percent  internal  con- 
verter drop  and  2  percent  transformer  regulation.  Constant  high  ten- 
sion voltage  in  both  cases. 


that  it  is  possible  to  obtain,  depending  upon  the  magni- 
tude of  the  reactance  used  and  the  extent  to  which  the 
converter  is  worked  in  wattless  current.  In  the  first 
case,  at  full  load  the  converter  armature  carries  only 
nine  percent  leading  current  at  290  volts  and  26.5  per- 
cent lagging  current  at  270  volts,  leaving  heating  ca- 
pacity in  the  converter  armature  for  additional  leading 
current  and  increased  voltage  boost  to  offset  any  high- 
tension  voltage  variation  that  would  tend  to  reduce  the 
voltage  range;  in  the  second  case  the  converter  arma- 
ture carries  28.5  percent  leading  current  at  290 
volts  and  28.5  percent  lagging  current  at  270  volts.  The 
converter  with  the  greatest  wattless  current  and  arma- 
ture heating  has  the  superior  high-tension  power-factor. 
At  no  load  the  converter  armature  wattless  current  is 
very  considerably  in  excess  of  these  figures.  The  pre- 
vailing power-factor  characteristic  on  the  high-tension 
line  is  thus  shown  to  be  lagging  over  the  greater  part 


56 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


of  the  voltage  range  of  even  the  most  favorable  of  the 
two  examples.  A  converter  having  poor  high-ten- 
sion power-factor  characteristics,  such  as  Fig.  2,  has 
a  large  permissible  voltage  range,  while  one  having  im- 
proved high-tension  power-factor  characteristics,  such 
as  Fig.  3  has  very  reserved  voltage  range  for  any  con- 
tingency. Flexibilit}'  in  this  respect  is  obtained  at  the 
expense  of  low  power-factor  on  the  high-tension  line. 

Effect  of  High-tension  Line  Voltage  Variation — 
On  a  simple  non-booster  type  converter,  having  a  rela- 
tively small  voltage  range,  any  variation  of  high-tension 
voltage  may  become  a  large  percentage  of  the  converter 
voltage  range  and  must  be  subtracted  directly  from  the 
voltage  range  obtainable  with  constant  high-tension 
voltage.  In  making  any  commercial  installation,  some 
allowance  must  be  made  for  such  a  contingency,  and  if 
this  high-tension  voltage  variation  is  likely  to  take  the 
form  of  a  drop  in  voltage,  it  means  that  the  upper  volt- 
age range  will  be  unobtainable  to  the  extent  of  high- 
tension  line  voltage  variation,  unless  the  converter  is 
worked  at  additional  wattless  current  during  this  time. 
Unless  the  power  company  has  absolute  assurance 
against  even  small  high-tension  voltage  variations,  it 
would  be  unsafe  to  install  a  simple  converter  that  was 
worked  up  to  its  limiting  amount  of  wattless  current  at 
full  load  maximum  voltage.  There  should  be  a  margin 
for  over-excitation  for  time  of  low  high-tension  voltage 
in  order  that  the  full  voltage  range  can  be  maintained. 

Efficiency — The  simple  non-booster  converter,  at 
the  middle  point  of  its  voltage  range,  has  a 
higher  efficiency  than  the  booster  converter,  due  to 
the  omission  of  the  booster  and  its  losses.  The  magni- 
tude of  this  difference  in  efficiency  may  however  be 
quite  small.  For  the  4000  kw  converter  with  a  35  volt 
up  and  down  range  the  losses  in  the  booster  at  full  load 
are  less  than  0.4  percent.  The  machine  efficiency  itself 
is  not,  however,  the  total  efficiency  of  the  converter  and 
transformer  as  a  unit,  and  it  is  the  total  efficiency  of  the 
unit  which  is  of  greatest  importance.  The  simple  non- 
booster  converter  works  at  a  considerable  lagging 
power-factor  on  the  high-tension  line  over  the  greater 
part  of  its  voltage  range  and  the  losses  in  the  trans- 
former, transmission  line  and  power  house  generating 
apparatus  incident  to  supplying  this  lagging  wattless 
current  must  logically  be  charged  against  the  efficiency 
of  the  simple  non-booster  converter  unit.  The  manu- 
facturer is  not  in  a  position  to  know  the  losses  in  these 
external  elements  due  to  this  condition,  but  it  is  evident 
that  a  mere  statement  of  machine  efficiencies  does  not 
tell  the  entire  story.  As  the  power  company  is 
primarily  interested  in  power  house  coal  consumption, 
it  should  consider  the  total  losses  involved  when  oper- 
ating this  type  of  converter  and  include  them  in  the 
converter  efficiency.  It  is  believed  that  an  efficiency 
comparison  on  a  proper  basis  will  show  the  booster  type 
machine,  when  operated  at  100  percent  power-factor  on 
the  high-tension  line,  to  possess  features  of  economy 
that  mav  not  be  evident  on  casual  examination. 


Comments  on  Power-factor  Measurements — In 
discussing  the  wattless  kv-a.  that  a  single  non-booster 
type  converter  requires  to  accomplish  its  voltage  regu- 
lation, it  has  become  customary  to  refer  to  the  wattless 
kv-a.  at  the  converter  terminals  rather  than  the  wattless 
kv-a.  on  tlie  high-tension  side  of  the  transformer.  This 
method  ignores  some  20  percent  of  the  machines'  rating 
in  wattless  kv-a.,  due  to  the  transformer  reactance  and 
some  five  percent  due  to  the  transfonner  magnetizing 
kv-a.,  a  total  kv-a.  of  25  percent  which  should  be  con- 
sidered in  discussing  the  power-factor  of  the  unit.  The 
present  practice  among  power  companies  of  connecting 
the  wattless  component  indicator  with  its  current  ele- 
ment on  the  high-tension  side  and  its  voltage  element 
on  the  low-tension  side  of  the  transformer  does  not  in- 
clude the  transformers  20  percent  reactance  kv-a.  on 
the  meter  reading,  a  fact  that  should  be  kept  clearly  in 
mind  when  receiving  data  on  tests  on  the  power-factor 
characteristics  of  converters.  With  the  booster  type 
unit,  using  a  five  percent  reactance  transformer,  the 
discrepancy  between  the  meter  reading  and  the  high- 
tension  power-factor  is  correspondingly  much  less. 

Facility  of  Starting — With  alternating-current  self 
starting  there  is  no  material  difference  between  the  two 
types  of  machines  as  the  same  control  apparatus  is  re- 
quired for  starting  both  of  them.  With  direct- 
current  starting  there  is  a  decided  handicap  in  getting 
simple  non-booster  machine  on  the  direct-current  bus 
at  times  of  heaviest  station  load  and  maximum  direct- 
current  voltage.  This  condition  arises  because  of  the 
absence  of  any  control  of  voltage  on  the  collector  side 
of  a  direct-current  started  converter,  until  the  machine 
is  switched  on  to  its  high-tension  line  and  can  draw  in 
wattless  currents.  At  this  time  the  direct-current  bus 
voltage  is  considerably  above  normal  and  the  collector 
ring  voltage  of  a  direct-current  started  simple  converter 
is  much  higher  than  that  of  the  incoming  line.  Because 
of  the  absence  of  voltage  control  it  is  necessary  to 
switch  the  converter  onto  the  alternating-current  system 
with  this  difference  in  alternating-current  voltage  exist- 
ing, thereby  drawing  a  hea\7  reversed  flow  of  current 
from  the  direct-current  system  at  a  time  when  it  is 
already  heavily  loaded. 

Commutation  Control — Converters  of  usual  design 
operated  off  unity  power-factor  do  not  commutate  per- 
fectly, and  if  commutator  and  brush  maintenance  ex- 
pense is  not  to  be  increased  in  this  type  of  tmit,  its  com- 
mutation performance  must  be  maintained  up  to  the 
usual  standard  by  commutation  control  devices,  either 
automatic  or  manual.  The  device  on  the  converter  will 
be  a  small  coil  on  the  commutating  poles  identical  with 
that  on  the  present  booster  type  machine,  with  a  con- 
trol only  slightly  modified. 

The  above  mentioned  features  are  the  major  ones 
wherein  the  booster  and  non-booster  type  machines  have 
different  characteristics.  These  characteristics  are 
almost  entirely  of  an  operating  nature  and  should  re- 
ceive the  careful  consideration  of  operating  engineers. 


A^ljM^'iaj^lo  UaborM^Dry  llLoo^tat^ 


THOMAS    SPOOMCk 


VARIOUS  types  of  adjustable  rheostats  are 
available  which  are  excellently  adapted  to  cer- 
tain purposes.  None  of  these,  however,  are 
altogether  satisfactory  for  many  laboratory  needs  and 
three  new  types  have,  therefore,  been  developed  which 
have  proved  widely  useful,  each  in  its  own  field. 

LAMP  BOARD  RHEOSTAT 

This  rheostat  is  a  very  compact  portable  lamp 
board  with  a  fine  adjustment  feature.  On  one  side  of 
a  vertical  board.  Fig.  i,  are  placed  as  many  lamp  sockets 
as  desired  and  directly  opposite  on  the  other  side  of 
the  board  are  placed  single-pole,  double-throw  baby 
knife  switches,  (one  more  switch  than  there  are  lamp 
sockets).  All  of  the  top  switch  break  jaws  are  con- 
nected by  a  bus  to  one  binding  post  B,  Fig.  2,  and  the 
bottom  jaws  to  the  other  binding  post.     A  lamp  is  con- 


FIG.    I — LAMP  BOARD  RHEOSTAT 


nected  between  each  pair  of  switch  hinge  jaws.  A 
small  slide  rheostat  having  a  resistance  slightly  greater 
than  that  of  one  lamp  is  connected  in  series  with  the 
right  hand  lamp. 

By  throwing  the  first  switch  up  and  the  last  one 
down,  with  the  rest  open,  all  of  the  lamps  are  connected 
in  series,  giving  the  maximum  resistance.  By  closing 
all  the  switches  alternately  up  and  down,  the  lamps  are 
thrown  in  parallel,  giving  the  minimum  resistance.  By 
proper  manipulation  of  the  switches,  any  series-paral- 
lel cormection  desired  may  be  obtained.  If  the  right 
hand  lamp  is  kept  always  in  circuit,  the  rheostat  R 
makes  it  possible  to  obtain  any  fine  adjustment  desired, 
between  the  steps  produced  by  the  change  of  one  lamp. 
Due  to  the  arrangement  of  lamps  and  switches,  the  wir- 
ing is  very  simple  and  direct,  and  practically  none  is 
exposed. 

VERTICAL    SLIDE    RHEOSTAT 

Several  t}-pes  of  slide  rheostats  are  available  but 
the  type  to  be  described  has  several  novel  features. 
The   rheostat  is   arranged   for  mounting  in   a   vertical 


position  as  shown  in  Fig.  3.  A  seamless  steel  or  brass 
tube  is  sawed  out  at  the  bottom  and  four  legs  formed 
from  the  tube  material,  no  casting  or  extra  parts  being 
required  for  a  base.  The  legs  are  drilled  so  that  the 
rheostat  may  be  screwed  down  if  desired.  The  tube  is 
then  enameled  or  other  suitable  insulating  coating 
applied  and  wound  with  oxidized  resistance  wire  or 
ribbon  such  as  30  percent  nickel  steel,  "nichrome",  or 
"advance".  The  advantage  of  "advance"  is  that  it  has 
practically  a  zero  temperature  coefficient  of  resistance. 
Before  winding,  the  wire  is  treated  in  a  furnace  with  an 
oxidizing  atmosphere  to  form  a  resistance  coating. 
This  may  be  done  by  putting  a  roll  of  wire  in  a  red 
hot  furnace  for  a  few  minutes  or  a  tube  furnace  may 
be  used  and  the  wire  drawn  through  at  a  slow  rate. 

The  sliding  contact.  Fig.  4,  consists  of  a  molded 
insulation  ring  having  an  internal  groove  containing  a 
helical  spring  which  surrounds  the  rheostat  tube.  This 
spring  is  connected  to  a  binding  post.     After  placing 


p 

b 

P\ 

0 

f] 

0 

0 

0 

p-| 

-■■y--- 

— 

— 

— 

— 

--. 

K 

K 

u 

A 

u 

A 

u 

A 

u 

r\ 

^xr 

LP 

LT 

un 

L^n_rLnLr 

FIG.   2 — WIRING    DIAGRAM    OF    L.VMP    DO.\RD   RHEOST.\T 

the  slide  in  position,  the  ends  of  the  resistance  wire  are 
fastened  to  suitable  end  terminals. 

If  "advance"  wire  is  used,  the  proper  size  for  a 
given  resistance  may  be  calculated  by  assuming  a  speci- 
fic resistance  of  294  ohms  per  circular  mil  foot.  If  a 
rheostat  has  been  built  with  any  given  size  of  wire, 
the  resistance  of  another  range  may  be  calculated  by 
assuming  that  the  resistance  varies  inversely  as  the  cube 
of  the  diameter  of  the  wire.  This  is  not  strictly  true 
however  since  for  smaller  sizes  the  oxidation  and 
stretching  due  to  winding  increase  the  resistance. 

If  it  is  desired  to  construct  a  rheostat  on  short 
notice  and  no  enameled  lube  is  available,  a  fairly  satis- 
factory insulation  consists  of  a  layer  of  asbestos  paper 
moistened  with  a  ten  percent  solution  of  sodium  sili- 
cate. After  baking  at  100  degrees  C,  this  makes  a 
fairly  hard,  tight  insulating  coating  but  is  not  as  satis- 
factorj'  as  the  enamel,  due  to  its  lower  thermal  con- 
ductivit)'. 

The  advantages  of  this  type  of  rheostat  are: — 

/ — The  vertical  arrangement  gives  a  chimney  effect 
which  aids  in  cooling. 

.? — The  vertical  arrangement  makes  it  possible  to  locate 
more  rheostats  in  a  given  space  on  a  test  bench. 

J — The  particular  form  of  sliding  contact  provides  a 
large  number  of  contact  points,  assuring  good  electrical 
connection  and  small  wear. 


58 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


4 — By  tipping  the  axis  of  the  ring  slightly,  an  adjust- 
ment of  less  than  one  turn  may  be  obtained. 

5 — It  is  impossible  for  the  sliding  contact  to  stick. 
COMPRESSION   RHEOSTAT 

There  are  several  makes  of  compression  rheostats 
on  the  market,  but  so  far  as  we  know,  they  all  use 
either  carbon  or  graphite  plates  and  therefore  have  a 
very  low  resistance  and  high  negative  temperature  co- 
efficient.      The    new    compression 
rheostat  has  a  large  range,  any  re- 
sistance desired  from  a  fraction  of 
an  ohm  to  many  megohms  and  a 
considerably  smaller  negative  tem- 
perature    coefficient    than    is    ob- 
tained with  carbon  or  graphite. 

The  resistance  material  itself*, 
is  in  the  form  of  rings  about  one 
inch  outside  diameter,  5/16  inch 
inside  diameter  and  3/16  inch 
thick.  By  using  the  proper  mix- 
ture, any  specific  resistance  desired 
may  be  obtained. 

The  resistance  material  is  ex- 
tmded  in  the  form  of  a  tube,  given 
the    proper   baking   treatment    and 
then     cut    into 
rings.  It  has  a 
much    lower 
temperature  coefficient  of  resist- 
ance   than    graphite    or    carbon. 
The  rings  are  arranged  in  three 
stacks,    forming    an    equilateral 
triangle,  with  a  copper  ring  be- 
tween   each    pair    of    resistance 
rings  as  shown  in  Fig.  5.     Each 
stack  is  supported  by  a  central 


tween  the  end  plates  and  take  care  of  the  thrust  pro- 
duced by  the  compression  screw.  This  screw  applies 
pressure  at  the  center  of  the  compression  plate,  thus  giv- 
ing equal  pressure  for  all  the  stacks. 

With  the  switch  5'  open.  Fig.  6,  the  three  resistance 
stacks  are  connected  in  series  with  the  binding  posts 


FIG.  3 — VERTICAL  SLIDE 
RHEOSTAT 


FIG.    5 — COMPRESSrON    RHEOST.^T 

P.  With  switch  6"  closed  the  three  stacks  are  connected 
in  parallel,  thus  giving  a  9  to  i  range  over  that  ob- 
tained by  compression  alone.  In  general  a  resistance 
range  of  200  to  i,  and  often  much  more,  may  be  ob- 
tained for  this  type  of  rheostat.  As  an  illustration  of 
the  possible  ranges  of  resistance  obtainable,  we  have 
one   rheostat   which   can   be  varied   from  60  ohms   to 


TABLE  I — CHARACTERISTICS  OF  THE  VARIOUS  TYPES  OF  RHEOSTATS 


Ca- 

Type 

pacity 
Watts 

Range* 

Limits 
Ohms 

Characteristics 

Remarks 

Lamp  Board 

1100 

200  to  1** 

Limited  by  lamps 

Non  •  inductive 

Capacity    based 

available 

easily    renew- 
able  elements 

on  ten  32  cp 
carbon    lamps 

Slide  rheostat 

600 

0  to  max. 

Min.  — 2 
Max.  ^  5000 

Z«ro  temp.  coef. 

"Advance" 
wire  15  inch 
tube 

Comp.   rheostat 

500 

200  to  1 

Min.  =1 

Max.  z:^  megohms 

Non-inductive 

Special  resistor 
material 

Range  is  for  s  given  rheostat. 

This    range    is   obtainable    with    carbon    lamps   running   cool    on    series  connection. 

30  000  ohms  and  another  which  has  limits  of  from  300 
ohms  to  400000  ohms.  The  rheostats  are  not  very 
stable  at  the  higher  ranges.  For  reasonable  constancy, 
the  second  rheostat  for  instance  should  not  be  used  for 
resistances  over  100  000  ohms.     By  the  use  of  the  three 


InriRnrLrn  ?  ? 

rtTLmirLrLrL  LIL 

-LnnRnrml  '" 


Binding  Post 


Metal  Tufc« 
FIG.   4 — SLIDING    CONTACT   FOR  VERTICAL   SLIDE   RHEOSTAT 

rod  insulated  with  a  glass,  porcelain  or  other  suitable  in- 
sulating tube.     The  central  rods  also  act  as  tie  rods  be- 


*Which  was  developed  by  Mr.  G.  M.  Little  of  the  Research 
Department  of  the  Westinghouse  Electric  &  Mfg.  Company. 


FIG.   6 — WIRING  DIAGRAM   FOR   COMPRESSION   RHEOSTAT 

Stacks,  each  may  be  made  fairly  short,  so  that  little  or 
no  trouble  is  experienced  from  unequal  pressure  due  to 
friction  of  the  resistance  rings  on  the  supporting  tube. 
The  copper  rings  serve  three  purposes: — 

I — To  conduct  away  the  heat,  thus  increasing  the  ca- 
pacity or  decreasing  the  change  in  resistance  for  a  given 
current  due  to  the  heating. 

2 — To  equalize  the  heat  over  the  surface  of  the  resis- 
tor, thus  reducing  the  possibility  of  permanent  changes  in 
the  material  due  to  minute  local  hot  spots. 

3 — When  made  in  saucer  form,  they  prevent  a  broken 


February-,  1921 


THE  ELECTRIC  JOURNAL 


59 


ring  from  falling  out.  A  broken  ring,  if  it  remains  in  posi- 
tion, is  as  satisfactory  as  a  whole  one,  since  the  breaks  are 
always  normal  to  the  surface. 

If  a  rheostat  is  to  be  operated  for  any  length  of 
time  at  high  capacity,  the  rings  should  be  of  a  metal 
which  will  oxidize  less  readily  than  copper,  such  as 
nickel  or  nickel  plated  copper.  A  rheostat  of  the  size 
shown,  having  stacks  eight  inches  long,  will  absorb 
about  one-half  kilowatt  continuously. 

The  chief  advantages  of  this  type  of  rheostat  are: — 


/ — Practically  non-inductive. 

3 — Large  capacity. 

3 — Low  temperature  coefucient. 

4 — Large  range  of  variation. 

5 — Any  order  of  resistance  desired. 

6 — Good  constancy  due  to  short  stacks. 

7 — Compactness. 

These  three  types  of  rheostats  should  meet  almost 
any  laboratory  needs  except  where  it  is  necessary  to 
absorb  energy  of  the  order  of  one  kilowatt  or  more. 


A  Yoctor  Diagram  for  >SaMoj]'i:»?Dlo  Alioriiaioi's 


E.  B.  SHAND 


IT  IS  well  understood  that  the  ordinary  vector  dia- 
gram as  applied  to  synchronous  machines  fails  to 
take  into  account  the  effect  of  salient-pole  construc- 
tion. In  most  cases  this  is  of  no  great  moment;  but 
where  the  stability  of  a  machine  operating  at  greatly 
reduced  excitation  is  in  question,  the  results  obtained 
from  the  diagram  are  so  widely  astray  that  some  modi- 
fication is  desirable. 

Ordinarily,  synchronous  machines  do  not  operate 
with  reduced  excitation,  but  occasionally  when  supply- 
ing a  load  of  high  inductive  capacity,  such  as  an  un- 
loaded   high-voltage    transmissive    line,    the    condition 


FIG.    I — ELLIPTIC    VECTOR    DL-\GR.\M    FOR    S.\LIENT-P0LE    ALTERNATORS 

Ii,  1=  —  armature  currents ;  Itj,  I<u  —  transverse  and  direct 
components  of  Ii;  Xs,  X.  —  total  reactive  e.m.f. ;  Xt,  Xo;  — 
transverse  and  direct  components  of  reactive  e.m.f.,  and  Eri, 
Et-  ^  voltage  at  terminals. 

exists.  In  the  case  of  synchronous  condensers  it  has 
even  been  contemplated  to  operate  with  a  small  amount 
of  reversed  excitation  to  cotmterbalance  the  leading  re- 
active currents.  A  modified  vector  diagram,  which 
might  be  called  an  elliptic  vector  diagram  is  therefore 
suggested  for  use  in  determining  the  stability  of  a 
salient-pole  synchronous  machine  for  such  operation.* 
Blondel   showed  in  his  various  writings  that   the 


*This  type  of  diagram  was,  so  far  as  the  writer  knows,  first 
proposed  by  Mr.  F.  Creedy,  a  British  engineer,  in  the  Journal 
of  the  Institute  of  Electrical  Engineers  1915-16,  p.  427. 


non-uniformity  of  the  reluctance  of  the  magnetic  cir- 
cuit due  to  the  salient-pole  construction  causes  a  vari- 
able reactive  effect  of  a  given  armature  current,  de- 
pending upon  whether  its  m.m.f.  acts  directly  opposite 
the  poles  or  opposite  the  interpolar  spaces.  In  the 
former  case  the  reactive  effect  is  a  maximum ;  in  the 
latter,  a  minimum.  He  called  these  effects,  respec- 
tively, those  of  direct  and  of  transverse  reactions.  The 
elliptic  diagram,  then,  is  based  directly  on  this  concep- 
tion of  two  reactions  and  takes  into  account  the  variable 
reactive  effect  of  the  current. 

In  Fig.  I  is  shown  the  elliptic  diagram  for  an  alter- 
nator. £g  represents  the  open-circuit  voltage  for  a 
given  excitation,  and  is  always  generated  in  the  con- 
d  u  c  t  o  r  s  directly 
under  the  poles,  /j 
is  a  current  in 
phase  with  E^.  It 
will  have  a  mini- 
mum reactive 
effect  -Y,,  because 
its  m.m.f.  is  op- 
posite the  inter- 
polar space.  The 
terminal  voltages 
is  £ii.  A  current 
/o  displaced  90  de- 
grees from  fg  will 
have    a    maximum 

reactive  effect  Xi„.  A  corresponding  current  in  any 
intermediate  phase  position,  say  I^,  may  be  resolved 
into  two  components,  one  in  phase  with  /j,  and 
the  other  with  /„,  viz.,  h^  and  h^  producing  the 
transverse  and  direct  reactive  effects  Xt,  and  X^^ 
with  a  combined  effect  X^  The  locus  of  this 
latter  reactive  voltage,  when  plotted,  is  found  to 
be  the  ellipse  so  designated  on  the  diagram.  It 
will  be  noted  that  the  current  I^  produces  a  reactive 
drop  X3  in  the  machine  which  is  not  proportional  to  the 
current  alone,  and  is  dispaced  90  degrees  from  it  only 
when  the  current  coincides  with  one  of  the  two  axes 
of  the  ellipse. 


Normal   Voluge 

/ 

/ 

fZ.^ 

/ 

■* 

<i/ 

/ 

0/ 

J 

7 

/ 

b 

.? 

f 

» 

Fit-ld  Amperes 
FIG.    2— XO-LOAD  AND  ZERO  POWER-FACTO.^ 
LOAD   SATURATION    CURVES 


6o 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


In  the  actual  use  of  the  diagram,  it  is  necessary  to 
determine  the  major  and  minor  axes  in  order  to  draw- 
in  the  ellipse.  When  this  is  done  a  current  may  be 
assumed,  say  I^,  and  oa  drawn  at  right  angles  to  it, 
cutting  the  circle  with  a  radius  equal  to  half  the  major 


— 180 
— 160 
—  HO 
— IJO 
—100 
-|-80 

/ 

\ 

/ 

/'' 

\ 

\, 

1 

/ 

\ 

\ 

1 

'^ 

"N,, 

\ 

■t- 

'/ 

/ 

s 

\ 

\ 

/ 

) 

■^ 

< 

1 

"v 

k^ 

n"^ 

5-  \ 

ll 

/■" 

/ 

V 

^ 

\u 

^^ 

\ 

1-20 

1^ 

/- 

,'"'' 

s'; 

h 

\- 

fe- 

.^\ 

\ 

v' 

V 

^ 

k. 

\. 

^ 

30 

—JO 

\ 

V 

\ 

^ 

y 

'      \ 

Rotor 

1          6 
3isplac 

)     ■    8 

0         1 
from  1 

•0         I 
0  Loa 

0        1 
Posit 

0       160       1 
3n  in  lj)«Kr«s 

0 

FIG.    3— mSPL.XCr.MENT   OF    ROTOR    FROM    NORMAL   POSITION   FOR   ANY 
TORQUE 

axis  at  a.  Then,  by  dropping  tlie  perpendicular  ah  to 
cut  the  ellipse  at  h  the  reactive  drop  oh  or  X^  is  ob- 
tained. 

The  major  axis  is  readily  determined  from  stand- 
ard test  data  just  as  it  would  be  for  circular  vectors. 
Let  Fig.  2  represent  the  open-circuit  saturation  curve 
and  full  load  saturation  curve  at  zero  percent  power- 
factor  of  an  alternator.  For  the  excitation  a,  draw  the 
intersecting  perpendicular  he  which  may  be  divided  by 
the  use  of  Potier's  triangle.  This  triangle  gives  a 
method  for  dividing  the  total  effect  of  the  armature  cur- 
rent at  zero  percent  power-factor  into  the  components 
of  armature  reactance  and  armature  reactions*.  Thus 
in  Fig.  2,  cd  represents  the  armature  reactance  voltage 
and  de  the  equivalent  magnetizing  field  current  needed 
to  overcome  the  armature  reaction.  Each  of  these  is 
then  considered  to  be  proportional  to  the  current.  The 
armature  reaction  e.m.f.  is,  therefore,  represented  by  hd. 
For  this  condition  the  major  axis  will  be  he.  The  ratio 
of  transverse  reaction  to  direct  reaction  for  any  ma- 
chine may  be  obtained  from  calculations.  For  usual 
proportions  for  salient  poles  at  fairly  low  saturations 
it  may  vary  from  55  to  60  percent,  depending  mainly 
on  the  ratio  of  pole-arc  to  pole-pitch.  In  the  present 
case  the  minor  axis  may  be  assumed  to  be  0.55  hd  -j-  de. 


The  reactance  drop  dc  is  assumed  to  be  independent  of 
phase  position.  The  remainder  of  the  construction  is 
quite  similar  to  that  for  ordinary  circular  vectors. 

The  displacement  of  the  rotor  from  the  normal 
position  for  any  torque  is  expressed  in  Fig.  3.  The 
curves  are  drawn  on  the  assumptions  that  the  ratio  of 
one  axis  to  the  other  is  0.65  and  that  the  short-circuit 
ratio  of  the  machine  is  unity.  It  will  be  noted  that  in_ 
every  case  the  maximum  torque  is  reached  before  the 
rotor-displacement  has  increased  to  90  electrical  de- 
grees, and  further  that  each  curve  may  be  considered  as 
the  combination  of  two  others — that  of  torque  with  no 
excitation  and  a  respective  dotted  curve.  The  dotted 
curve  is  one  obtained  from  the  ordinai-y  circular  vector 
diagram,  assuming  a  synchronous  reactance  correspond- 
ing to  that  expressed  by  the  minor  axis  of  the  ellipse. 

Fig.  4  represents  the  line  of  the  maximum  torques 
replotted  from  figure  3.  The  dotted  curves  in  either 
case  are  supposed  to  apply  to  a  turbine-generator  wnth 
£.  smooth  rotor.  The  two  curves  give  an  indication  of 
the  relative  stabilities  of  the  two  types  of  machines. 

When  the  case  of  a  synchronous  condenser -with 
no  mechanical  load  is  considered,  the  steady  torque 
necessary  to  operate  the  machine  is  inappreciable.  The 
operation,  however,  may  become  unstable  before  the 
reversed  excitation  is  increased  to  any  considerable  ex- 
tent, because  the  synchronizing  torque  necessary  for 
stability  may  be  greatly  in  excess  of  the  steady  value. 
This  is  equivalent  to  saying  that  the  torques  resisting 
the  action  of  hunting  become  decreased  to  such  an  ex- 
tent that  it  is  difficult  to  prevent  the  machine  from  slip- 
ping a  pole  during  any  incidental  disturbance.  This  can 


160 

^140 

|.30 

/ 

'  / 

^ 

/. 

/ 

~^W_ 

1-80 

^    rn 

^*5 

/' 

'f/ 

/ 

y 

I 

^ 

f 

4- 

20 

/ 

<= 

■ 

y 

/ 

/ 

r^ 

5 — '■ 

Perc 

0 

nt  of 

Jormal 

0       y       6 
No-Lcjad  Ex 

f — ' 

)  1 

" 

*See  "Regulation  of  Definite  Pole  Alternators"  by  S.  H. 
Mortensen,  Transactions  A.  I.  E.  E.,  February,  1913. 


FIG.   4— LINE  OF   MAXIMUM   TORQUES   REPLOTTED  FROM    FIG.   3 

be  seen  from  the  negative  torque  values  of  Fig.  3,  which 
represent  the  operation  on  reversed  excitation. 

The  effect  of  saturation  has  been  neglected ;  it  will 
tend  to  reduce  the  difference  between  the  two  axes  of 
the  ellipse.  This  may  be  allowed  for,  although  the  re- 
sulting difference  is  not  great  for  a  machine  of  normal 
design. 


Typical  .lloJay  i^ojiiioccioj]^ '!( 


Li:v\  IS  A.  TICKVLN 


WHEN  the  neutral  point  of  a  group  of  star-con- 
nected generators  operating  in  parallel  is  to 
be  connected  to  ground,  it  is  important  that 
only  one  generator  be  grounded  at  a  time,  in  order  to 
avoid  circulation  of  third  harmonic  currents.  It  is 
usually  necessary,  however,  to  provide  a  connection  to 
ground  through  a  circuit  breaker  from  each  of  the  gen- 
erators, in  order  that  any  generator  may  be  operated 
singly  at  times  of  light  load.  In  such  cases,  it  is  desir- 
able to  have  some  form  of  relay  interlock,  so  that  if  the 
operator  attempts  to  close  a  ground  circuit  breaker 
when  another  is  already  closed,  the  incoming  circuit 
breaker  will  automatically  trip  out  any  other  that  is 
already  closed. 

An  example  of  this  application  of  relays  is  shown 
in  Fig.  5,  the  circuits  of  which  can  be  traced  by  assum- 
ing that  any  one  of  the  circuit  breakers,  for  instance, 
the  one  on  the  left  hand,  is  to  be  closed.  Positive  con- 
trol current  will  flow  through  wire  6"  to  wire  Y  which  is 
negative,  closing  the  oil  circuit  breaker,  which  in  turn 
will  cause  the  auxiliary  or  pallet  switches  to  assume  the 
upper  position.  The  interlock  relay  will  then  be  ener- 
gized, tracing  the  positive  through  wire  G,  the  right 
hand  pallet  switch,  the  operating  coil  and  the  main  con- 
tacts to  wire  Y  which  is  negative,  causing  the  plunger 
of  the  relay  to  rise,  which  in  turn  opens  the  main  con- 
tacts and  closes  the  auxiliary  contacts,  breaking  its  own 
circuit  in  the  coil  as  has  been  previously  explained. 
Due  to  the  oil  dashpot  time  element  device,  several  sec- 
onds will  elapse  after  the  coil  is  energized  before  the 
main  contacts  will  be  broken.  It  is  thus  seen  that  any 
circuit  breaker  which  is  in  circuit  will  have  its  relay  set 
with  open  main  contacts  and  closed  auxiliary  contacts. 

Now  assume  that  the  operator  closes  circuit 
breaker  No.  2.  When  the  auxiliary  switches  rise  to  the 
closed  position  as  before,  the  operating  coil  of  the  inter- 
locking relay  belonging  to  circuit  breaker  No.  2  which 
has  just  been  closed  will  be  energized,  but  some  time 
will  elapse  before  the  main  contacts  are  open  and  the 
auxiliary  contacts  close.  Meanwhile  a  circuit  is 
established  over  wire  G,  positive  of  the  second  breaker, 
through  a  pallet  switch  on  the  circuit  breaker  to  wire 
G  of  the  cross  wires  in  the  diagram  and  on  through  the 
trip  coil  of  the  first  circuit  breaker,  through  the  pallet 
switch  of  the  first  breaker,  the  auxiliary  contact  of  the 
first  breaker's  interlocking  relay,  to  negative,  causing 
the  first  breaker  to  trip.  An  examination  of  the  dia- 
gram will  show  that  no  matter  which  circuit  breaker 
may  be  closed,  any  incoming  breaker  will  trip  the  one 
which  is  in  service.  As  soon  as  any  circuit  breaker 
opens,  the  return  of  the  pallet  switches  to  the  lower 
position  makes  a  circuit  from  positive  through  the 
latch  releast  coil  to  negative  which  will  cause  the  relay 


jilunger  to  return  to  its  normal  or  lower  position  with 
the  main  conlacts  of  the  relay  closed  and  the  auxiliary 
contacts  open. 

Still  another  purpose  for  which  the  relay  described 
in  the  preceding  diagrams  can  be  used  is  shown  in  Fig. 
0,  where  a  flexible  connection  from  the  main  contact 
bridge  is  connected  to  a  binding  post  which  leads  to  an 
annunciator  drop.  With  this  design  the  bell  can  be  used 
for  a  number  of  breakers,  while  an  annunciator  drop  is 
provided  for  each  relay.  In  some  cases  each  panel 
controlling  two  circuit  breakers  is  provided  with  an 
annunciator  drop  and  in  some  cases  a  relay  is  provided 
for  each  breaker,  so  that  an  annunciator  signal  may  be 
given  to  the  chief  operator  for  each  breaker  of  the  sys- 
tem.    The  same  relay  can  be  used  for  signal  lamp  pur- 


5ignal  Relav  Time  EI. 
fUpper  Contact 
Open  When  Lowf 

and  \l 

+ 


KIG.    5 — CONNECTIONS    OF    KKI.AY     I-OR     INTF.RI.OCKING    GROUND    CIR- 
CUIT BRE.\KERS 

poses  and  in  some  cases  the  auxiliary  contact  shown 
in  Fig.  5  is  added,  being  used  in  connection  with  cer- 
tain features  of  the  circuit  breaker  control. 

Reference  has  previously  been  made  to  the  fact 
that  when  the  operating  circuit  of  the  direct-current 
auxiliary  relays  must  be  kept  separate  from  the  in- 
dividual circuits  which  are  to  be  made  by  the  relay, 
additional  segments  on  the  control  switches  will  not 
answer  the  purpose.  Multi-contact  relays  such  as 
shown  in  Fig.  8  are  admirably  adapted  to  the  end  in 
view,  and  applications  will  be  given  later.  The  relay 
contacts  close  instantly  when  the  main  coil  is  energfized 
and  open  immediately  when  the  coil  is  de-energized. 
One  exception  to  the  above  occurs  with  the  multi-con- 
tact relay  (d)  which  has  one  finger  for  making  a  con- 
tact for  bell  alarm  purposes.  This  finger  will  remain  in 
the  closed  position  when  operated  until  mechanically  re- 


62 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


FIG.   6 — BELL    ALARM     RELAY 
WITH   ANNUNCIATOR  CON- 
TACTS 


leased  by  a  small  push  button  which  opens  the  contact 
against  friction.  In  cases  of  large  systems  where  the 
control  circuit  for  tlie  different  busses  are  kept  separate, 
multi-contact  relays  are  very  serviceable  and  they  are 
also  of  use  in  differential  protection  of  apparatus  where 
an  internal  failure  requires  the  isolation  of  the  machine 
involved,  removing  all 
sources  of  incoming  or 
outgoing  power  from  it. 
In  relay  {d)  one  set  of 
contacts  opens  as  the  other 
three  close,  and  vice-versa. 
A  relay  whose  appli- 
cation is  the  reverse  of 
that  shown  in  Figs,  i  to  4, 
is  shown  in  Fig.  7.  The 
purpose  of  this  relay  is  to  open  the  circuit  instantly  upon 
an  impulse  passing  through  its  operating  coils,  the  cir- 
cuit thus  established  being  interrupted  by  the  pallet 
switch  of  the  circuit  breaker.  Once  the  circuit  through 
the  coil  is  interrupted  the  main  contacts  of  the  relay 
will  slowly  settle  into  the  closed  position,  a  definite 
time  elapsing  as  determined  by  the  setting  of  the  small 
dashpots  indicated  in  the  diagram.  The  general  use 
of  this  relay  is  to  interrupt  a  companion  circuit  until 
the  function  of  the  first  circuit  is  completed.  For  ex- 
ample, where  a  short-circuit  occurs  on  one  of  two 
parallel  transmission  lines,  it  is  desirable  to  prevent  the 
operation  of  the  circuit  breakers  on  the  other  line  until 
after  the  breakers  on  both  ends  of  the  short  circuited 
line  have  opened,  thereby  clearing  the  fault. 

A  reverse-power  direct-current  relay  is  shown  in 
Fig.  9  which  is  instantaneous  in  operation.  It  consists 
of  a  stationary  potential  coil  which  produces  a  magnetic 
field  in  which  is  a  movable  current  coil  connected  across 
an  ammeter  shunt.  The  moving  coil  carries  contacts 
for  closing  an  auxiliary 
d  i  r  e  c  t-current  control 
circuit.  This  relay  is 
essentially  a  wattmeter 
which  is  mechanically 
prevented  from  moving 
in  the  positive  direction 
but  closes  its  contacts 
quickly  upon  a  reversal 
of  the  direction  of 
power  flow.  By  the  use 
of  double  contacts,  this 
same  relay  can  be  ar- 
ranged to  close  a  second 
circuit  in  the  reversed 
direction.  Such  an  in- 
strument is  very  sensi- 
tive to  the  potential  drop  in  the  shunt  and 
the  moving  coil  can  be  so  wound  as  to  cause  tripping  at 
very  low  values  of  potential  difference  at  the  shiuit. 
However,  for  positive  operation,  ample  potential  differ- 


FIG.    7 — CONNECTIONS      OF     RELAYS 
FOR     OPENING    ONE   CIRCUIT  IN- 
STANTANEOUSLY 

Operation  of  one  circuit 
breaker  prevents  the  other  cir- 
cuit breaker  from  tripping  until 
time  interval  has  elapsed. 


ence  is  desirable,  the  high  resistance  shunt  being  used 
or  sometimes  a  section  of  the  main  conductor  of  the 
circuit. 

This  relay  is  quite  sensitive  and  is  used  with  elec- 
trically operated  circuit  breakers  for  reverse  power  op- 
eration. For  mechanically  operated  circuit  breakers, 
such  as  the  usual  type  of  carbon  circuit  breaker,  the 


U 


^ 


f£22 

1! 

JJJJJ5 

T  TTTl T 

'd)  (e)  (1) 

FIG.   8 — MULTI-CONTACT   REL.\YS 

(a)  Three  contacts;  (b)  Six  contacts;  (c)  Eight  con- 
tacts, two  opening  and  six  closing;  (d)  One  finger  held  latched 
requiring  manual  release;   (e)    Six  contacts;   (f)  Two  circuits. 

type  of  relay  shown  in  Fig.  10  is  applicable.  For  ordi- 
nary reverse  current  application  the  overspeed  device 
should  be  considered  as  having  its  contact  closed.  The 
two  coils  in  each  shunt  circuit  are  wound  for  opposite 
polarities  and  the  polarities  of  the  upper  coils  are  re- 
versed from  the  lower  ones,  so  that  the  diagonal  coils 
are  of  the  same  polarity.  A  coil  in  series  with  the  car- 
bon circuit  breaker,  not  shown  in  the  diagram,  assists 
the  magnetic  flow  through  the  lower  coils  and  bucks 
that  through  the  upper  coils,  keeping  the  armature  in 
its  lower  position.  A  reversal  of  current  in  the  series 
coil  causes  it  to  buck  the  flux  in  the  lower  shunt  coils 
and  boost  that  in  the  upper  shunt  coils,  lifting  the  arma- 
ture and  tripping  the  circuit  breaker.  The  field  strengths 
are  adjusted  so  that  a  relatively  small  reversed  current 
is  sufficient  to  cause  the  circuit  breaker  to  trip. 

The  overspeed  device,  which  is  not  an  essential 
part  of  die  reversed  current  attachment,  is  used  on  syn- 


FIG.   Q — DIRECT-CURRENT  REVERSE-POWER  RELAY 

chronous  converters  to  prevent  their  attaining  a  de- 
structive speed  upon  reversal  of  power.  It  operates  to 
interrupt  the  shimt  circuit  through  the  lower  pair  of 
coils,  permitting  the  upper  coils  to  lift  the  armature 
and  trip  the  circuit  breaker.  Overloads  are  cared  for 
by  an  entirely  separate  series  coil  which  trips  the  circuit 
breaker  on  overloads  only.  It  should  be  noted  that  the 
auxiliary     pallet     switch     used     with     carbon     circuit 


Febmary,  1921 


THE  ELECTRIC  JOURNAL 


63 


breakers  is  shown  reversed  from  the  symbol  used  for     the  negative  control  bus.     This  operation  will  close  the 
oil  circuit  breakers.     This  fact  should  be  borne  in  mind     contact  of  the  auxiliarj^  relay,  causing  the  blower  motor 


to  operate,  and  at  the  same  time  the  toggle  switch  will  be 
moved  to  the  right-hand  position,  which  leaves  the 
right-hand  coils  of  the  auxiliary  relay  disconnected. 
This  means  that  any  further  chattering  of  the  tempera- 
ture relay  contacts  will  produce  no  current  in  the  right- 
band  coil.  When  the  temperature  becomes  sufficiently 
low  to  allow  a  circuit  to  be  established  through  binding 


speed  Device  Oi 
Opening  ,^_ 


FIG.    10 — REVERSE   CURREXT   TRIP 


in  connection  with  the  diagrams  which  follow. 

Carbon  circuit  breakers  are  usually  provided  with 
internal  overload  tripping  devices,  and  they  may  also 
be  equipped  with  low  voltage  coils  which  will  trip  the 
latch  upon  failure  of  voltage.     Fig.  1 1   shows  an  over- 

I  a  d  direct-current 
relay  arranged  to  dis- 
connect all  of  the 
carbon  circuit  break- 
ers connected  to  that 
circuit,  by  opening 
the  low-voltage  cir- 
cuit of  the  circuit 
breakers,  the  pallet 
switches  being  in  series  with  the  low-voltage  coils. 
Although  this  latter  arrangement  is  common, 
usually  no  useful  result  is  accomplished,  because  in 
case  of  low-voltage,  the  amount  of  current  to  be  in- 
terrupted in  the  low'-voltage  coils  is  quite  small.  If  the 
overload  relay  should  operate  there  would  be  no  current 
to  be  broken  by  the  pallet  switches.  On  the  other  hand 
on  the  return  of  voltage  to  the  circuit  the  pallet  switches 
will  prevent  this  voltage  from  being  impressed  upon 
the  low-voltage  coils  while  the  circuit  breakers  them- 
selves are  open. 

An  application  of  the  relay  shown  in   Fig.  9  for 
temperature  control  purposes  is  shown  in  Fig.  12.     This 
relay  serves  to  control  the  operation  of  a  motor  driven 
blower  which  forces  air  through  the  circulating  system 
of  the  machine  in   which   a  search   coil   is   embedded. 
The  operation  of  the  temperature  relay   system   is  as 
follows : — The  search  coil  forms  one  leg  of  a  wheat- 
stone  bridge  which  is  balanced  at  normal  temperatures, 
so  that  only  small  amounts  of  current  will  flow  through 
the  relay.     The  resistance  of  the  search  coil  increases 
with  its  temperature,  so  that  at  a  predetermined  high 
temperature  the  bridge  will  be  enough  unbalanced  to 
send  a  sufficient  current  through  the  relay  to 
cause  the   contacts  on  the  high  temperature 
side  to  close.     It  is  obvious  that  the  contacts 
of  the  temperature  relay  must  be  quite  sensi- 
tive and  of  the  floating  type.     For  this  reason 
an   auxiliaiy    relay   must   be   installed   which 
will    fulfill   two   objects;   first   to   handle   the 
larger  current  which  is  required  for  the  con- 
trol of  the  blower  motor,  and  second  to  give  a 
positive  operation  which  will  cause  the  switch 
to  stay  in  the  closed  position  until  the  temper- 
ature relay  has  reached  the  other  extreme  of 
its  travel  and  thus  shut  off  the  blower  motor 

when  the  temperature  has  been  reduced  to  the  lower  closed  it  will  be  tripped.  The  desirability  of  this  con- 
limit.  The  current  may  be  traced  from  the  positive  con-  tact  may  be  seen  from  the  fact  that  the  operator 
trol  bus  to  binding  post  6,  through  the  relay  contact  to  through  accident  might  attempt  to  throw  a  motor  into 
binding  post  5,  through  the  right-hand  auxiliary  relay  the  starting  position  when  it  was  already  running.  In 
coil  to  the  left-hand  toggle  switch  contacts  and  thence  to     the  second  position  all  three  of  the  left-hand  contacts  of 


kk;.  ii--co.\.n'kctio.\s  kok  riRKcr-ccRRENT  in eri.oau  relay 
p.ost  6,  contacts  of  the  relay,  binding  post  7,  left-hand 
coil  of  the  auxiliary  relay  and  right-hand  side  of  the 
toggle  switch,  when  the  auxiliary  relay  will  open  its 
circuit  and  the  toggle  switch  will  be  set  back  to  the 
left-hand  position.  For  accurate  operation  of  sucn  a 
system  it  is  desirable  to  have  the  control  circuit  at  a 
constant  voltage,  because  the  amount  of  current  which 
llows  in  the  inov..'  i.  .•■intact  of  the  temperature  relays, 
as  well  as  in  the  permanent  coil  of  this  relay,  is  directly 
proportional  to  the  voltage  of  the  direct-current  control 
circuit. 

An  interesting  diagram  exemplifying  the  use  of  a 
sequence  relay  is  shown  in  Fig.  13.  The  object  of  the 
sequence  relay  is  to  prevent  the  operator  from  connect- 
ing a  motor  across  full  line  voltage,  w-ithout  having 
gone  through  the  starting  position,  and  it  furthermore 
reduces  the  time  interval  between  the  opening  of  the 
starting  breaker  and  the  closing  of  the  nmning  breaker 
to  a  minimum. 

A  special  motor  starting  control  switch  is  shown, 
the  first  operation  being  to  short-circuit  the  two  upper 
left-hand  contacts  which  will  cause  negative  control 
current  to  be  impressed  upon  the  tripping  coil  of  the 
running  circuit  breaker,   so   that   should   the  latter  be 


)R    TEMI'ER.ATURE    REL.\Y 


64 


THE   ELECTRIC  JOURNAL 


\'o\.  XVIII,  No.  2 


the  control  switch  will  be  short-circuited  and  negative 
control  current  will  pass  over  wire  CS  and  through  the 
open  position  of  the  pallet  switch  of  the  running 
breaker  to  positive,  causing  the  control  relay  of  the 
magnetizing  and  starting  breakers  to  operate,  the  clos- 
ing coils  of  the  latter  two  breakers  being  connected  in 
parallel.  The  pallet  switch  interlock  of  the  running 
breaker  is  an  additional  safeguard  against  closing  the 
starting  equipment  when  the  running  breaker  is  in. 
Upon  the  magnetizing  and  starting  breakers  going  into 
the  closed  position  the  pallet  switches  rise  to  the  upper 
contacts  thereby  establishing  a  circuit  from  the  positive 
control  bus  through  the  coil  of  the  interlocking  magnet 
switch  or  sequence  relay  through  the  upper  contacts  of 
the  pallet  switch,  on  both  the  magnetizing  and  starting 
breakers,  and  back  to  the  negative  control  bus.  The  in- 
terlocking magnet  switch  closes  its  auxiliary  contacts  at 
the    same    time    that    the   main    contact    closes.     Now, 


causes  the  sequence  relay  to  open,  thus  completing  the 
operation. 

An  emergency  stop  pushbotton  is  provided  to  en- 
able the  operator  to  impress  tripping  current  upon  the 
trip  coils  of  all  of  the  circuit  breakers  of  the  system,  so 
that  should  any  difficulty  arise  at  any  stage  of  the  start- 
ing operation,  all  the  breakers  can  be  returned  to  the 
open  position.  It  is  also  desirable  to  use  the  emer- 
gency stop  pushbutton  for  tripping  the  running  breaker 
in  normal  service  because,  unless  the  motor  starting 
control  switch  is  provided  with  a  mechanical  interlock, 
it  is  possible  for  a  careless  operator  to  rotate  the  left- 
hand  contact  too  far  on  the  control  switch  drum,  caus- 
ing the  cycle  of  starting  the  motor  to  commence  with 
the  resulting  temporary  short  circuit  on  the  motor."  The 
control  wires  are  so  numbered  and  lettered  that  cables 
may  easily  be  provided  between  the  switchboard  and  the 
breaker  compartments  as  well  as  between  the  different 


AuxiUaty  Conuti 


jCX 


[^—ELliCTRICAl.I.y-OPERATF.n       MOTOR        STARTING       EQUIPMENT 
WITH    KI.KCTRlrAI.    INTERLOCK 


FIG.    14— MECHANICALLY-OPERATED  EQUIPMENT 
WITH    LOCKOUT    COII. 


when  the  controller  is  thrown  over  to  the  right-hand 
position,  negative  current  will  flow  from  the  lower 
right-hand  stud  of  the  control  switch  through  the  aux- 
iliary contact  to  the  coil,  of  the  sequence  relay,  thereby 
locking  it  shut.  With  the  controller  in  the  right-hand 
position,  current  will  pass  from  the  negative  control 
bus  to  the  upper  studs  of  the  control  switch  over  the 
wire  marked  TS  and  through  the  trip  coils  and  pallet 
switches  of  the  magnetizing  and  starting  breakers, 
causing  these  breakers  to  open.  At  the  same  time  cur- 
rent will  flow  from  the  negative  control  bus  through  the 
lower  right-hand  stud  of  the  control  switch  to  the  main 
contacts  of  the  sequence  relay  and  through  the  closing 
coil  of  the  control  relay  to  wire  CR',  but  the  circuit  to 
the  positive  control  bus  is  not  completed  until  the  pallet 
switches  of  the  magnetizing  and  starting  breakers  have 
both  assumed  the  open  position.  When  this  is  accom- 
plished, the  nmning  breaker  will  close  and  the  control 
switch  is  returned  to  the  normal  or  open  position  which 


breakers  of  the  set.  A  red  lamp  lights  when  any  of 
the  circuit  breakers  is  closed,  while  a  green  lamp  indi- 
cates that  all  three  of  the  circuit  breakers  are  open. 

In  some  cases  the  oil  circuit  breakers  are  rendered 
fully  automatic  by  the  arrangement  of  the  control  re- 
lays. In  such  a  case  the  operation  of  the  oil  circuit 
breaker  upon  closing  is  to  open  the  main  closing  coil 
circuit  mechanically  by  pulling  open  the  clapper  of  the 
control  relay.  At  the  same  time  a  floating  armature  is 
moved  into  such  a  position  that  the  magnetic  circuit  of 
the  control  relay  is  short-circuited  and  current  flowing 
through  the  coil  of  the  control  relay  will  produce  no 
effort  to  close  the  clapper  contact.  Under  such  circum- 
stances the  tripping  coil  of  the  circuit  breaker  is  free  to 
operate  no  matter  in  what  position  the  controller  may 
be. 

When  the  motor  is  started  by  means  of  mechanic- 
ally-operated circuit  breakers,  a  lockout  coil  may  be 
used  to  accomplish  the  same  result  as  with  the  electrical 


February,   1921 


THE   ELECTRIC  JOURNAL 


65 


interlock  just  described.  A  scheme  of  this  kind  is 
illustrated  in  Fig.  14  where  a  motor  is  started  by  a 
double-throw  mechanically-operated  circuit  breaker. 
The  starting  position  impresses  a  reduced  voltage  upon 
the  motor  until  it  comes  up  to  speed  and  the  running 
position  of  the  breaker  impresses  full  voltage  on  the 
motor  terminals.  A  lockout  coil  controlled  by  a  relay 
mechanically  prevents  full  voltage  being  thrown  on  the 
motor  in  case  the  operator  carelessly  closes  the  running 
side  of  the  breaker  without  going  through  the  starting 
operation ;  and  also  gives  a  definite  time  interval 
within  which  the  running  position  must  be  assumed 
after  throwing  out  the  starting  breaker.  In  case  the 
operator  opens  the  starting  breaker  and  fails  to  close 
the  running  breaker  before  the  time  interval  has  ex- 
pired, it  would  be  dangerous  to  connect  the  motor  at  re- 
duced speed  across  the  full  line  voltage,  consequently 
the  whole  cycle  of  operation  must  be  gone  over  again. 

Referring  to  Fig.  14,  when  the  auxiliary  switch  is 
cpen  the  coils  of  the  lockout  relay  are  not  energized. 
Upon  closing  the  starting  breaker  the  auxiliary  switch 


assumes  the  upper  position,  causing  current  from  line 
2  to  pass  through  the  release  coil  of  the  lockout  relay, 
which  will  open  the  auxiliary  contact  and  close  the 
main  contact  of  this  relay.  The  main  contacts  establish 
;>.  circuit  from  line  2,  through  the  lockout  coil  and  the 
main  contacts  of  the  relay,  holding  the  plunger  of  the 
lockout  mechanism  in  the  raised  position,  where  it  will 
remain  as  long  as  current  flows  in  the  lockout  coils,  pre- 
venting the  closing  of  the  running  position.  When  the 
starting  breaker  is  opened,  current  will  flow  from  line  2, 
through  the  lower  position  of  the  auxiliary  switch  and 
through  the  reset  coil  of  the  lockout  relay,  and  the  main 
contacts  to  line  i.  The  reset  coil  being  energized,  the 
lockout  relay  will  open  its  main  contacts  within  a 
definite  time,  according  to  the  setting  of  the  dashpot, 
but  during  the  time  of  suspense  the  lockout  coil  is  still 
energized,  allowing  the  operator  to  throw  the  motor  into 
the  running  position.  The  final  condition  of  all  coils 
will  be,  as  at  the  start,  completely  de-energized  while  the 
motor  is  running,  or  while  both  starting  and  running 
■^witches  are  open. 


C.  J.  RODMAN  and  T.  SPOONER 

Research  Laborator\-, 
Wcstinghoiise  Electric  &  Mfg.  Company 


ALL  necessary  units  for  electrical  measurements 
may  be  defined  in  terms  of  the  ohm,  ampere, 
volt  and  second.  The  ohm  is  defined,  by  inter- 
national agreement,  as  the  resistivity  of  a  uniform 
column  of  mercurj'  of  a  certain  weight  and  length  at  a 
given  temperature.  Tlie  ampere  is  defined  as  the  cur- 
rent which  will  deposit  electrolytically  from  a  solution 
of  silver  nitrate  a  definite  weight  of  silver  in  a  given 
time.  The  volt,  as  at  present  defined,  is  derived  from 
the  ohm  and  ampere  and  is  the  e.m.f.  that,  steadily  ap- 
plied to  a  conductor  whose  resistance  is  one  inter- 
national ohm,  will  produce  a  current  of  one  inter- 
national ampere.  This  definition  of  the  volt  does  not 
supply  us  with  a  working  standard.  The  need  of  a 
working  standard  is  best  met  by  what  is  known  as  a 
standard  cell.  Such  a  cell  consists  of  a  suitable  posi- 
tive and  negative  electrode  in  an  electrolyte.  The  es- 
sential characteristics  are  permanency,  reproducibility 
and  low  temperature  coefficient. 

The  Clark  normal  cell  has  been  the  legal  standard 
in  the  United  States  since  1894.  The  positive  electrode 
is  a  zinc  rod  and  the  negative  is  mercury  in  a  paste  of 
mercurous  sulphate  and  zinc  sulphate.  The  solution  is 
zinc  sulphate  and  the  whole  is  enclosed  by  a  glass  con- 
tainer. More  recently,  it  has  been  found  that  the 
Weston  normal  cell  is  much  superior  in  all  respects.  It 
was  adopted  by  the  Bureau  of  Standards  as  a  working 
standard  in  the  United  States  on  January  i,  1911. 
The  positive    electrode    is    a    12.5    percent    cadmium 


amalgam  and  the  negative  is  mercury  with  a  mercurous 
sulphate  and  cadmium  sulphate  paste.  The  electrolyte 
is  a  cadmium  sulphate  solution.  This  cell  is  readily  re- 
producible when  sufficient  care  is  taken  in  the  prepara- 
tion of  the  chemicals.  Several  hundred  cells  of  this 
t}'pe  have  been  manufactured  by  the  Bureau  of  Stand- 
ards and  are  held  as  standards  of  e.m.f.  These  stand- 
ards have  been  checked  against  the  standard  ohm  and 
ampere  and  against  the  standards  of  other  National 
Laboratories.  The  e.m.f.  of  this  cell  is  taken  as  1.0183 
volts  at  20  degrees  C. 

The  normal,  or  saturated  cell  is  not  as  satisfactory 
for  commercial  purposes  as  the  unsaturated,  due  to  the 
fact  that  the  former  has  an  appreciable  temperature  co- 
efficient, while  the  latter  has  a  temperature  coefficient 
of  e.m.f.  which  is  entirely  negligible  for  ordinary  com- 
mercial work.  This  latter  form  is  the  one  which  is 
commonly  used.  It  differs  from  the  saturated  form 
(inly  in  the  concentration  of  the  electrolyte. 

The  commercial  uses  of  the  standard  cell  are  not 
numerous,  but  these  cells  form  an  essential  part  of  cer- 
tain types  of  apparatus  as  may  be  judged  from  the  fact 
that  several  thousands  are  sold  each  year.  They  find 
their  chief  use  with  potentiometers.  The  potentiometer 
is  the  most  accurate  method  available  commercially  for 
measuring  voltage,  and  all  high  grade  instruments  have 
as  an  essential  part,  a  standard  cell  as  a  unit  of  refer- 
ence. The  potentiometer  is  usually  limited  in  accuracy 
nnlv  bv  the  accuracy  of  the  standard  cell.     The  accur- 


THE   ELECTRIC  JOURNAL 


Vol.  X\III,  No.  2 


..J,  of  all  voltmeters,  ammeters,  and  wattmeters  is  de- 
,  rrmined  usually  by  potentiometer  tests,  as  the  standard 
instruments  are  always  calibrated  by  this  means.  In 
many  standardizing  laboratories,  instead  of  using  stand- 
ard instruments,  the  voltmeters,  ammeters,  etc.,  are 
calibrated  directly  by  means  of  potentiometers. 

A  second  very  con- 
sidei-able  use  of  standard 
cells  is  in  connection  with 
thermocouple  indicators  of 
t  h  e  potentiometer  type. 
(  )ne  of  the  most  accurate 
methods  of  measuring  tem- 
])erature  is  by  means  of  the 
I  li  e  r  m  o  couple  combined 
w  lib  a  suitable  indicator  or 
recorder.  The  most  accur- 
ate indicators  work  on  the 
potent  iometer  principle, 
and  contain  standard  cells 
FIG.  I — CONSTRUCTION  OF  THE  as  uuits  of  reference. 
H-TYPE  CELL  Where    millivoltmeters  are 

used  for  indicators,  their  calibrations  are  ultimately  re- 
ferred to  potentiometer  measurements. 

iMom  this,  we  see  that  most  electrical  measure- 
ments are  referred  ultimately  to  the  standard  cell  and 
depend  for  their  accuracy  on  the  reliability  of  the  cells. 
Much  has  been  written  on  the  subject  of  standard  cells, 
and  undoubtedly  the  best  combination  for  great  stability 
is  the  cadmium  cell,  as  indicated  above.  The  chemicals, 
Hg  I  HgjSO^  I  CdSO^  (saturated)  |  Cd  amalgam, 
which  enter  into  its  composition  may  be  easily  prepared 
in  a  pure  state,  if  proper  precautions  are  adopted. 

In  order  to  increase  the  dependability  of  this  type 
of  cell,  new  materials  for  the  container  and  leads  have 
been  tried  and  adopted.  In  order  to  increase  the  com- 
pactness, the  old  H-type  of  cell,  shown  schematically 
in  Fig.  I,  has  been  abandoned  and  a  concentric  type 
having  a  diameter  of  about  one  in.  and  a  height  of  about 
3.5  in.  has  been  developed. 

DEVELOPMENT  OF  CELL 

Neiu  Materials — The  high  percentage  of  failures  of 
cells  of  soda  glass  with  platinum  leads,  of  the  H-type, 
led  to  the  selection  of  another  combination  of  metal  and 
glass.  Soda  glass  has  a  coefficient  of  expansion  of 
8.33  X  lO"*.  and  platinum  8.99  X  10  *at  room  tempera- 
tures, so  that  even  well  annealed  seals  often  cause  leaks 
or  cracks  in  the  glass.  Other  factors,  as  the  mechanical 
strength  and  chemical  stability  of  soft  glass,  failure  of 
seals  due  to  the  zinc  amalgam  of  the  Clark  cell  causing 
the  platinum  contact  wires  to  crack  the  glass,  etc.,  may 
be  cited  as  reasons  why  other  combinations  have  been 
tried.  It  is  obvious  that,  as  leading-in  wires,  only 
metals  can  be  used  which  will  be  inert  to  any  constituent 
that  the  finished  cell  contains. 

The  latest  design  consists  of  a  hard  silica  glass  con- 
tainer which  has  a  coefficient  of  expansion  of  3.50  X 


lo"*",  and  tungsten  leads  of  3.60  X  10''.  In  selecting  a 
stable  hard  glass  for  this  purpose  a  high  silica  pyrex 
was  chosen.  Such  glass  has  been  found  to  be  highly 
insoluable  toward  the  slightly  acidic  properties  such  as 
are  encountered  in  standard  cell  conditions.  Such 
compositions  as  sulphur,  rosin,  sealing  wax,  etc.,  make 
quite  an  appreciable  difference  in  cell  construction. 
Some  of  the  latter  ingredients  have  been  used  in  cer-: 
tain  makes  of  standard  cells  for  plugs  and  seals  and 
have  shown  no  drastic  ill  effects,  but  where  the  best 
equilibria  are  desired  it  is  advisable  not  to  use  them. 

In  order  to  make  a  good  tungsten-glass  seal  it  is 
necessary  to  clean  the  metal  thoroughly.  Boric  acid  is 
used  for  this  purpose.  A  thin  coat  of  BoOj  is  allowed 
to  remain  upon  the  wire  after  the  fluxing  action  has 
taken  place.  It  is  necessary  to  heat  the  tungsten  to  a 
cherry  red  during  the  sealing-in  of  the  wire.  Most  of 
the  thin  coat  of  B^Oj  is  taken  up  into  the  glass.  Should 
any  be  left  free  upon  the  wire,  it  should  be  completely 
washed  off  with  water  when  the  cell  is  cleaned.  B2O3. 
as  well  as  other  acid  oxides  occurring  in  the  glass,  when 
taken  up  by  the  cadmium  sulphate  solution  has  a  tend- 
ency to  depress  the  e.m.f.  of  the  cell,  whereas  other 
oxides  in  the  composition  of  the  glass,  such  as  PbO, 
ZnO,  NaoO,  K^O,  etc.,  when  dissolved  in  the  solution 
increase  the  e.m.f.  Alumina  and  silica,  as  such,  have  no 
noticeable  effect  upon  the  cell  equilibria.  However, 
with  the  glass  used  no  appreciable  effect  was  observed 
due  to  the  interaction  of  the  glass  with  the  cell  ingre- 
dients. 

It  is  interesting  to  note  that  the  cell  contents  pene- 
trate the  high  lead  and  basic  oxide  glas.ses  to  an  appre- 
ciable depth,  depending  upon  the  time  of  standing  of  the 
cell.  By  emptying  the  cell 
and  heating  the  blank  to 
the  temperature  of  the 
softening  point  of  the  glass 
and  cooling,  a  definite 
crazing  effect  may  be  ob- 
served, that  penetrates  uni- 
formly to  a  depth  of  a  few- 
tenths  of  a  millimeter. 
Similar  phenomena  are 
produced  by  acid  treatment 
and  heating  of  certain 
glasses. 

The  cells  made  of  hard 
glass  with  tungsten  seals 
are   very   strong  and   dur- 

able.  No  failure  of  the  ^^^  2_construction  of  new 
many  cells  made  thus  fir  concentric  type  of  standard 
can    be    attributed    to    the  ^''^'''- 

hard  glass-tungsten  junction,  whereas  many  of  the  soft 
glass  cells  with  platinum  leads  have  proven  mechanically 
weak,  have  crazed  or  cracked. 

NEW    FORM 

For  constant   laboratory   use,   stable   portable   cells 


Februan',  1921 


THE  ELECTRIC  JOURNAL 


67 


are  needed.  The  first  attempt  to  produce  such  a  cell 
resulted  in  a  modification  of  the  H-type  which,  while 
an  improvement,  was  later  abandoned  in  favor  of  the 
concentric  type,  which  is  shown  in  Fig.  2.  The  outside 
dimensions  of  the  concentric  cell  blank  are  2.5  cm.  dia- 
meter and  10  cm.  high.  The  outer  compartment  is 
tubular  in  form  with  closed  bottom,  and  is  slightly  in- 


\K1A    CASKS 
IXCEMRIC 


Kli;.    3— THE     II-TY'PE     .\.NL)     THE    CDXCEMRIC     CELLS     MOUNTED     IN 

dented  near  the  lower  end,  so  that  the  tungsten  leading- 
out  wires  can  be  bent  sharply  at  right  angles  just  outside 
the  glass  wall,  thus  leaving  a  form  which  is  flush  with 
the  diameter  of  the  outer  compartment.  A  glass  tube 
1.6  cm.  outside  diameter  is  sealed  concentrically  with 
the  outside  glass  tube  and  forms  the  cathode  leg  of  the 
cell.  In  addition  to  being  sealed  at  the  upper  con- 
stricted portion  of  the  central  tube,  which  is  about  six 
cm.  from  the  bottom  of  the  cell,  it  is  sealed  at  a  point 
near  the  bottom  and  furnishes  contact  with  the  outer 
glass  tube  so  that  a  tungsten  lead  can  be  made  to  con- 
nect the  inner  portion  of  the  cathode  without  being  elec- 
trically connected  with  the  anode  chamber.  Just  below 
the  upper  seal  and  about  five  cm.  from  the  bottom  of 
the  cathode,  a  hole  about  one  cm.  in  diameter  serves  to 
connect  the  anode  chamber,  which  can  be  filled  from 
that  point.  The  cathode  tube  extends  several  centi- 
meters beyond  the  upper  joint  so  that  after  the  cell  is 
tilled  it  can  be  conveniently  drawn  out  and  sealed  off. 

As  No.  24  tungsten  wire  is  very  stiff  and  difficult 
to  bend  when  cold  without  breaking,  so  a  flexible  lead 
was  devised  which  prevents  breaking  of  tiie  wire.  Just 
outside  the  tungsten  leading-in  wire,  a  tungsten-monel- 
copper  joint  was  made  by  electro-spot  welding.  Such  a 
combination  holds  ver\^  tenaciously  and  if  the  copper 
wire  is  redoubled  back  a  short  distance  on  the  tungsten 
and  wound  about  the  joint  a  \evy  flexible  lead  is  made. 
The  difference  in  temperature  between  the  leads  on 
either  side  of  the  cell  is  very  small.  The  correction  for 
the  thermal  e.m.f.  is  less  than  2.5  )<  lo'  volts  per  de- 
gree. The  contact  e.m.f.  in  the  leads  is  obviously  bal- 
anced one  against  the  other  as  the  finishing  lead  consists 
of  copper  wire. 

The  cells  are  mounted  in  a  bakelite-niicarta  cases 
fitted  with  suitable  binding  posts.     The  top.  bottom  and 


sides  of  the  cell  proper  are  protected  from  breakage  by 
felt  pads.  Although  the  diameter  of  the  cell  base  is 
only  about  two  inches,  thi  cell  is  verj'  stable,  since  the 
center  of  gravity  is  low  due  to  the  mercury  near  the 
bottom.  Figs.  3  and  4  show  by  comparison  the  com- 
position of  the  new  form  of  ceil.  Due  to  the  low 
thermal  conductivity  of  the  walls  of  the  container  and 
the  high  thermal  conductivity  and  intimate  contact  of 
the  two  legs  of  the  cell  proper,  external  changes  of  tem- 
i;erature  should  have  little  effect  on  the  e.m.f.  of  the 
unsaturated  cell. 

CELL  INGREDU'.NTS* 

Chemically  pure  mercury,  as  obtained  on  the 
market,  usually  contains  many  other  metals  and  must 
he  specially  purified  before  being  used  in  standard  cells. 
This  is  done  by  simultaneous,  continuous  acid  washings 
Mid  electrolysis,  the  refined  mercury  being  finally  dis- 
tilled in  a  vacuum  still. 

The  mercttrous  sulphate  is  prepared  from  the  re- 
fined mercurj-  by  the  electrolytic  method. 

I'hc  paste  is  made  from  the  mercurous  sulphate  by 
mixing  it  with  about  ten  percent  b)'  volume  of  about 
15  mesh  3  Cd.SO.,  8  H„0  crystals  and  making  it 
of  the  consistency  of  thick  cream  by  the  addition  of 
saturated  CdSO^  solution. 

The  cadmium  obtained  from  the  manufacturer  is 
redistilled  in  a  hard  glass  vacuum  still,  the  resultant 
product  being  very  pure. 

Tlic  amalgam,  consisting  of  12.5  percent  by  weight 
of  cadmium,  is  made  by  dissolving  the  purified  cad- 
mium in  mercury  at  a  temperature  slightly  above  lOO 
degrees  C. 


I  l"E  .\ND  THE   NEW   ST.\ND.\RD 


The  cadmium  sulphate,  as  received  from  the  manu- 
facturers, containes  small  amounts  of  iron,  nickel,  zinc 
and  traces  of  other  impurities,  .so  that  it  is  necessary 
to  resort  to  further  purification  of  this  material  also. 


*A  compkti-  description  of  ihc  apparatus  and  methods  used 
in  purifying  the  materials  used  in  these  standard  cells,  together 
with  a  complete  bil)liography,  is  given  in  a  paper  In-  the  au- 
thors before  the  .American  Electrochemical  Society,  Sejitember 
30,  1020,  upon  v.hic''  this  article  is  based. 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


FILLING  THE  CELL 

As  has  been  stated  in  the  description  of  the  cell 
blank,  Fig.  2,  the  central  chamber  is  made  the  cathode 
while  the  outer  concentric  tube  is  made  the  anode.  The 
cadmium  amalgam  is  introduced  through  the  circular 
opening  near  the  top  of  the  cathode  tube  by  means  of  a 
smaller  glass  tube  which  is  curved  so  that  all  the  amal- 


101870 

"-0  01860 
■  jH.01850 

S-1.01840 

»       i 
a-1.01830 

—1.01820 

1.01810 

1 

l-C 
2-C 

jdl  No.  10 
ell  Ko.  10: 

S-Cell  m  106 

6.ciu  N4   107 

i- 

^' 

^ 

a-ceii  ^o  10 

4-Cell  ^o.  10 

^    ^ 

s 

^ 

?-fJ — 

l>^ 

i^ 

^ 

1 

=3 

= 

:= 

0 

T 

3 

r 

nJys 

T 

LT_ 

hr 

-.p 

-SERIES    OF   VOLTAGE   TESTS   OF   A    SET   OF    SATURATED    H-TYVt 
STANDARD   CELLS 


gam  enters  the  chamber.  A  depth  of  1.5  cm.  is  suffi- 
cient to  cover  the  tungsten  lead.  The  spherical  part 
of  the  leg  of  the  cathode  chamber  is  filled  slightly  more 
than  half  full  with  mercury.  The  paste,  as  described 
above,  is  carefully  pipetted  into  the  cathode  chamber  so 
that  it  covers  the  mercur}-  to  a  depth  of  about  2  cm. 
Two  methods  are  used  to  hold  the  mercuiy  and  paste  in 
position.  The  first  method,  which  has  been  used  hereto- 
fore, consists  in  thnisting  a  silk-covered  hollow  cork 
ring  down  upon  the  surface  of  the  paste.  The  opening 
through  the  hollow  cork  is  about  0.5  cm.  in  diameter. 
To  insure  the  plug  from  chemically  affecting  the  e.m.f. 
of  the  cell,  it  is  first  thoroughly  boiled  in  water,  dried 
free  from  moisture  and  allowed  to  soak  several  days  in 
saturated  cadmium  sulphate  solution.  Acid  treated  silk 
which  has  been  thoroughly  washed  and  dried  exists  in  a 
stable  condition  in  contact  with  the  cell  ingredients. 
The  alternate  method  of  holding  the  paste  and  mercury 
in  position  consists  in  using  a  clean  coil  (two  turns)  of 
No.  28  tungsten  wire,  which  is  slightly  larger  than  the 
cathode  tube,  to  replace  the  cork.  A  slight  annular 
concave  depression  made  in  the  cathode  tube  when  con- 
structing the  blank  serves  to  hold  the  silk  and  coil  in 
the  proper  position. 

The  cell  is  next  filled  to  the  upper  seal  with  the 
saturated  cadmium  sulphate  solution  in  which  a  few 
crystals  of  clear  3CdS04  8H„0  have  been  added. 
By  placing  the  cell  in  cold  water  to  a  depth  of  6.5  cm.  a 
smooth  seal  is  made  by  judiciously  softening  the  hard 
glass  with  the  heat  of  the  oxygen-natural  gas  flame. 

ELECTRICAL  TESTS 

After  completion,  these  cells  ware  tested  periodi- 
cally with  a  potentiometer  to  determine  the  constancy 
of  the  e.m.f.  Six  portable  unsaturated  cells  of  the 
Weston  type  served  as  standards.  Four  of  these  cells 
were  sent  to  the  Bureau  of  Standards  for  check  at 
various  times  and  a  weighted  mean  of  the  certificate 


values  of  these  six  cells  was  used  in  checking  the  new 
cells.  The  cells  were  not  placed  in  an  oil  bath,  but  be- 
fore checking  they  were  kept  in  the  standardization 
room  for  several  hours  and  the  air  temperature  close  to 
the  cells  noted.  The  temperatures  were  accurate  to  at 
least  one-half  degree.  Fig.  5  shows  a  series  of  tests 
covering  a  period  of  2.5  years  for  an  early  set  of  satu- 
rated H-type  cells  made  up  of  hard  glass  arid 
tungsten  leads.  These  cells  show  a  smaller 
variation  of  e.m.f.  than  do  the  individual 
portable  cells  used  for  standardizing  them. 
Table  I  gives  a  record  of  the  e.m.f.  of  a  set  of 
unsaturated  cells  of  the  concentric  type. 
These  have  not  been  kept  for  a  long  enough 
period  to  give  useful  data  on  their  constancy. 

FACTORS   AFFECTING   THE   STABILITY  OF  STAND- 
ARD CELLS 

Such  changes  noted  at  the  mercurj-  sur- 
face as  the  hydrolysis  and  formation  of  basic 
the     solution    give    an     increase    of'    e.m.f; 


salt 

as  the  mercurj'  concentrates.  Crystalline  basic  salts 
stop  increase  of  free  acid  formation  due  to  hydro- 
]\sis,  which  has  a  tendency  to  lower  the  e.m.f. 
The  e.m.f.  is  also  decreased  by  evaporation  of 
the  liquid,  by  the  change  in  the  crystalline  state  of 
the  cadmium  sulphate  and  by  the  inequality  of  the 
grain  sizes  of  the  mercurous  sulphate.  It  is  obvious 
that  the  cell  blanks  must  be  absolutely  clean  and  the 
chemicals  used  must  be  of  excellent  purity.  A  cell 
\\hich  is  very  slightly  acid  makes  a  satisfactory  work- 
ing standard.  A  slight  variation  in  the  composition  of 
the  cadmium  amalgam  has  no  harmful  effect  upon  the 
e.m.f. 

The  tungsten  leading  into  the  interior  of  the  cell 
legs  is  usually  covered  with  a  small  quantity  of  tungstic 
oxide.  This  is  reduced  electrolytically  in  dilute  H2SO4 
at  the  cathode,  which  leaves  a  very  thin  layer  of  spongy 
tungsten  about  the  wire.  Mercury  is  deposited  upon 
the  tungsten  immediately  by  adding  a  small  quantity  of 

TABLE  I— E.  M.  P.  OF  CONCENTRIC  CELLS 


Cell 

E.  M.  F 

900 

1.01822 

(JOI 

1.01821 

902 

1.01824 

903 

1.01813 

904 

1.01821 

c,07 

1.01810 

Q08 

1.01815 

909 

1.01811 

910 

1.01814 

911 

1.01824 

mercurous  nitrate  to  the  electrolyte.  It  is  probable  that 
a  slight  amalgamation  of  the  tungsten  is  produced  in 
this  case.  On  emptying  the  electrolyte  from  the  blank 
and  after  subsequent  washings  with  distilled  water,  the 
tungsten  leads  remain  bright  due  to  the  electrolytically 
deposited  mercury.     This  process  of  amalgamation  of 


February,  1921 


THE  ELECTRIC  JOURNAL 


69 


the  leads  gives  a  very  stable  contact  with  the  cell  and  is 
free  from  the  high  resistance  effects  which  accompany 
untreated  electrodes. 

ADVANTAGES  OF  THE  PORTABLE  CELL 

The  portable  cell  as  described  has  at  least  five  dis- 
tinct advantages : — 


I — Compactness. 

2— The  cathode  is  centrally  located,  holding  the   mer- 
cury in  a  central  chamber. 

3 — Stability  of  construction. 

4 — I-egs  are  kept  at  the  same  temperature,  thus  reduc- 
ing E.  M.  F.  variations. 

5 — Constant  electromotive   force  is  obtained  over  lonf; 

periods  <>\   time. 


Air-  liroak  Typ- 


G.  G    GRI.SSINGER 

Supply  I'-nginccring  Dept., 
W'estiiighousc  Electric  &  Mfg.  Company 


ROTARY  converters  and  motor  generator  sets, 
when  applied  to  railway  or  similar  heavy  duty 
service,  are  frequently  called  upon  to  carry 
sudden  and  heavy  overloads  or  short-circuits  which, 
unless  suitable  protection  is  provided,  play  havoc  with 
the  commutating  parts  of  the  machines.  Various 
methods  of  obtaining  such  protection  have  been  devised, 
the  most  recent  of  which  is  the  high-speed  circuit 
breaker. 

It  is  the  function  of  the  high-speed  circuit  breaker 
shown  in  Fig.  i,  to  open  an  electric  circuit  after  a 
short-circuit     occurs, 

so    quickly,    that    the  ^^mm    ^ 

current  will  be  un- 
able to  reach  a  dan- 
gerously high  value. 
To  the  eye  the  ordi- 
nary carbon  circuit 
breaker  opens  a 
short-circuit  w  i  t  h 
great  rapidity,  yet 
the  current  is  able  td 
reach  the  maximum 
value  before  the  cir- 
cuit breaker  starts  to 
open.  Oscillograms 
show  that  the  current 
on  short-cir  cuit, 
starting  from  zero 
value,  builds  up  at  the  rate  of  from  one  million  to  three 
million  amperes  per  second,  depending  upon  the  con- 
stants of  the  circuit.  This  means  that  a  value  of  10  000 
amperes  would  be  reached  in  from  o.oi  to  0.003  seconds. 
Fig.  4  represents  the  action  of  a  carbon  circuit 
breaker,  which  is  automatic  on  overload,  w^hile  opening 
?.  dead  short-circuit  on  a  500  kw,  60  cycle,  600  volt 
rotary  converter.  The  current  attained  a  value  of 
about  25  000  amperes  before  the  circuit  breaker  started 
to  open.  The  circuit  was  opened  completely  in  0.075 
seconds   and   an   arc   was   started   between   the   circuit 


mum  value  in  0.03  second,  and  hence  that,  in  order  to 
limit  the  short-circuit  current  to  a  value  considerably 
below  12  000  or  15  000  amperes,  a  circuit  breaker  would 
be  required  which  operated  more  than  ten  times  as  fast 
as  the  carbon  circuit  breaker. 

To  design  such  a  circuit  breaker,  for  750  volt,  1200 
ampere  service,  for  e.xample,  which  will  be  siiuple, 
compact  and  rugged  is  not  a  simple  problem.  In  order 
to  obtain  the  extreiuely  high  speed  necessar}',  powerful 
springs  are  required  to  give  the  proper  acceleration. 
.Ml  of  the  [larls  which  move  when  the  circuit  breaker 

opens  must  be  liijht, 
and  at  the  same  time 
nuist  be  strong 
enough  to  withstand 
the  slamming  action 
of  the  springs.  The 
method  of  holding 
the  circuit  breaker 
closed  against  these 
heavy  springs  is  of 
great  importance, 
since  the  method  of 
tripping  the  circuit 
breaker  depends 
primarily  upon  the 
method  of  holding 
and  the  speed  of 
opening  depends  to  a 
great  extent  on  the  scheme  of  tripping. 

'i"he  construction  of  the  circuit  breaker  which 
solves  this  problein  is  shown  in  Figs,  i  and  2.  The 
upper  contact  of  copper  leaves,  clamped  together,  is 
indicated  by  r/.  It  is  connected  electrically  with  the 
series  coil  D.  The  lower  contact  g',  similarly  con- 
structed, is  connected  to  the  stud  for  main  line 
lead.  .\  copper  member  /;,  hinged  at  the  point  //, 
is  ]irovided  with  an  auxiliary  copper  contact  or 
arcing  tip  a'  at  its  upper  end,  which  serves  to  make 
or     break     the      connection     between     the     contacts 


,\-\ll   KEAK   VIKW    OK    HIGH-SPEED   ClRCflT  nREAKER 


breaker  carbons  in  appr  )ximately  0.05  second  froin  the  cj  and  g'.     AV'hen   the   handle   C   is   pushed   downward 

mstant  of  short  circuit.     These  figures  represent  very  by  hand,  the  toggle  lever  t  forces  the  copper  bridging 

short    intervals   of   time,    yet   an   examination    of    this  member  b  against  the  powerful  springs  5";  and  thus  g 

oscillogram  will  show  that  the  current  reached  its  maxi-  and  g'  are   electrically   connected.     The   electromagnet 


70 


THE   ELECTRIC  JOURNAL 


Vol.  XMII,  No.  2 


M,  by  pulling  upon  the  iron  structure  A',  holds  the  cir-  coil  creates  a  magnetomotive-force,  which  shunts  most 
cuit  breaker  in  the  closed  position  until  it  is  tripped  of  the  flux  away  from  the  armature  A'',  thereby  allowing 
electrically  '^^    compressed   springs    to   open    the   circuit   breaker. 

The   magnetic   blow-out    device,    which    serves    to     The  time   consumed   from   the  instant  of   short-circuit 
blow  out  the  arc  formed  by  the  arc  tips  a  and  a'  when     until   the   armature  A''   starts   to   move   is   about   o.ooi 

F  second. 

It  is  evident  that  this  method  of  holding  the  circuit 
breaker  closed  and  of  tripping  it,  is  ver^'  simple  and  effi- 
cient. There  are  no  latches  and  levers  to  fail  or  wear 
cut,  and  the  speed  of  operation  is  much  faster  than  one 
could  ever  hope  to  obtain  with  a  system  of  triggers. 

The  operation  of  this  circuit  breaker  in  an  actual 
circuit  is  represented  by  the  oscillogram  in  Fig.  5.  A 
500  kw,  60  cycle  rotary  converter  was  short-circuited 
through  0.15  millihenries  reactance.  It  is  plain  that  the 
line  current  was  unable  to  reach  the  maximum  value, 
given  in  Fig.  4,  which  represents  a  short-circuit  on  the 
same  machine  with  the  same  circuit  characteristics.  In 
the  oscillogram  shown  in  Fig.  5,  the  current  was 
limited  to  a  little  less  than  6000  amperes,  which  is  less 
than  one-third  of  the  value  which  it  would  have  att.lined 
had  a  plain  carbon  circuit  breaker  been  used  in  place  of 


CONSTRUCTION   OF    HIGH-SPEED   CIRCUIT   HREAKER 


the  circuit  breaker  opens,  consists  of  a  magnetic  circuit 
E,  a  series  coil  D  and  an  arc  chute  F.  The  coil  D. 
which  is  connected  in  series  with  the  line,  produces  a 
magnetic  flux,  which  passes  through  the  iron  E,  and  be- 
tween the  pole  pieces  K  which  extended  downward  u< 
the  sides  of  the  arcing  tips  a  and  a'.  The  strong  mag- 
netic field  exerts  an  upward  force  on  the  arc  formed 
between  the  tips  a  and  a',  blowing  it  out  through  the 
vent  of  the  chute  F. 

A  diagram  of  the  electrical  connections  is  shown 
in  Fig.  3.  The  coils  B  and  B',  connected  to  a  suitable 
source  of   direct-current,  energize   the  holding  magnet 


,— l-.LIXTRK-AI.    CONNECTIONS    OF    HIUH-SIT-EH    CIKCLIT    RREAKEi 


M.  The  trip  coil  T  is  connected  across  the  line  reactor 
R  and,  in  the  event  of  a  short-circuit  in  the  line,  re- 
ceives a  heavy  rush  of  current  due  to  the  high  voltage 
drop  across  the  reactor.     This  current  through  the  trip 


FIG.   4 — ACTION  OF  A  CARBON  CIRCUIT  BREAKER 
FIG.   5 — ACTION   OF  THE   HIGH-SPEED   CIRCUIT   BREAKER 

the  high-speed  circuit  breaker.     As  a  result  the  flash- 
ing on  the  commutator  was  eliminated. 

The  current  in  the  line  was  limited  in  about  0.0044 
second  and  the  circuit  was  broken  completely  in  approxi- 
mately 0.0084  second.  To  obtain  an  idea  of  how  fast  this 
is,  consider  the  peripheral  speed  of  the  commutator  of  a 
rotaiy  converter.  Assuming  that  there  are  six  brush 
arms  and  that  the  commutator  is  revolving  at  the  rate 
of  1200  r.p.m.,  it  would  take  a  commutator  bar  about 
0.0083  second  to  pass  from  one  brush  arm  to  the  next. 

High-speed  circuit  breakers  of  the  type  described 
above  should  prove  very  useful  in  protecting  the  feeder 
circuits  of  direct-current  machiner}'.  At  the  present 
time,  in  most  trolley  systems,  costly  feeder  cables  are 
run  out  a  mile  or  more  from  the  sub-station,  so  as  to 
insure  a  sufficient  amount  of  current  limiting  resistance 
and  reactance  in  the  circuit  wlien  a  short  circuit  occurs 
on  the  system.  Costly  and  inefficient  resistors  are 
sometimes  used.  All  of  the  .e  can  be  eliminated  by 
means  of  high-speed  circuit  breakers  and  therefore  a 
considerable  investment  can  he  saved  by  their  use. 


i'   r 


'[((IplllOllX 


J.  A.  WHITE 

Industrial   Dcpt., 
Westinghousc  F.li-ctric  &  Ml'g.  O 


inpaiiy 

THE   PRODUCTION  of  nearly  every  photoplay     graphic  results,  direct  current  is  vastly  superior  tu  aller- 
invohes    a    certain    amount    of    outdoor   photo-     nating  current   lor  motion  picture  work.     Since  direct 
graphy  in  order  to  obtain  a  clear  and  complete     current   at    115    volts   is   seldom,   if   ever,   available   at 
lotographic  interpretation  of  the  story.     To  witness  a     ].oints   where    required,   either  portable   converting   or 

)mplete  generating  equipment  is  necessary  to  secure 


incture  lacking  in  the  important  outdoor  action  is 
analagous  to  reading  a  narrative  void  of  description  and 
one  in  which  many  of  the  important  incidents  compris- 
ing the  story  are  not  related.  The  extent  to  which  out- 
door photography  enters  into  the  production  of  the  pic- 


rect  current  for  operating  the  lamps.  In  the  vicinity 
of  Los  Angeles,  portable  motor-generators  are  used  ex- 
tensively, as  alternating  current  usually  is  available.  In 
localities  where  no  electric  power  is  available,  a  com- 


ing small  motor-driven  dexices. 


ture,  depends  upon  the  nature  of  the  play  and  also  the  plete  portable  power  plant  is  required.  The  direct  cur- 
care  exercised  by  the  producers  to  secure  a  photoplay  rent  produced  is  used  in  photographing  either  day  or 
showing  a  sequence  of  events,  including  all  the  outdoor  night  scenes,  and  when  occasion  demands,  for  operal- 
happenings,  which  contribute  to  a  clear  interpretation 
of  the  story.  Outdoor  scenes  must  be  taken  either  in 
the  daytime  or  at  night,  and  at  points  where  the  sur- 
roundings are  in  harmony  with  that  particular  part  of 
the  story  to  be  photographed.  Quite  frequently,  in 
order  to  secure  the  proper  "setting",  this  work  must  be 
done  at  places  considerably  distant  from  the  studio.  In 
studio  vernacular,  outdoor  photography  is  called  "loca- 
tion work". 

During  the  past,  location  work  has  been  very 
costly.  Excessive  delays  were  frequently  encountered, 
due  to  lack  of  sufficient  daylight,  whicK  made  it  neces- 
sary to  keep  the  players  and  equipment  "on  location" 
until  proper  lighting  conditions  prevailed.  Further- 
more, this  work  often  extended  over  a  period  of  several 
days  and  {he  variation  in  the  photographic  value  of  day- 
light, occasionally  necessitated  a  repetition  of  the  work. 
This  meant  a  delay  and  consequenttly  additional  ex- 
pense, which  was  not  conducive  to  economy  in  [iroduc- 
ing  the  picture. 

The  b.igh  cost  of  location  work  was  a  matter  of 
much  concern  to  motion  picture  producers  and  lead  to 
the  almost  universal  use  of  artificial  light  with  daylight, 
as  a  solution  to  the  existing  problem  of  greater  ecoffomy 
in  the  production  of  outdoor  [lictures.  .\rtificial  il- 
lumination in  connection  with  daylight  not  only  gives 
far  better  results  than  daylight  alone  but  it  also  permits 
the  location  work  to  proceed  regardless  of  natural  light 
conditions,  thus  eliminating  delays  and  unnecessary  ex- 
pense. Wonderful  effects  are  secured  by  using  artificial 
light  for  ]]hotographing  night  scenes,  which  previously 
were  taken  in  daylight  making  it  necessary  to  tint  the 
films  to  obtain  the  night  effect.  The  past  year  is 
significant  in  the  history  of.  motion  pictures  in  that  it 


SET   FOR    I.OCAT10.I 


Showing  the  direct-current  gencralor  panel  on  the  left,  and 
the  alternating-current  control  e(|uipincnt  consisting  of  an  auto 
starter  and  2200  volt  oil  circuit  breaker,  the  transformers,  and 
the  integrating  watthour  meter. 

The  equipment  shown  in  Fig.  i,  is  owned  by  the 
Lois  Weber  Productions  Company,  Los  Angeles,  and 
consists  of  a  100  kilowatt  three-unit  induction  motor- 
generator  with  switchboard  and  accessories,  all  mounted 
-on  a  chassis. 

The  portable  power  plant,  shown  in  Figs.  2  and  3 
was  designed  by  Mr.  Otto  Sarvas,  electrical  engineer. 


marks  a  general  recognition  of  the  relati\e  importance  of  the   Auto-electric   Devices   Corporation,   New   York 

of  artificial  illumination  in  outdoor  photograjjhy  and  the  Cit\-,  and  used  by  the  Sunlight  Arc  Corporation,  New 

development  of  satisfactory  equiprnent  for  this  service.  York  City.     This  ecjuipment  consists  of  a  so  kilowatt, 

On  account  of  greater  economy  and  better  photo-  1-^5     volt,    ooo    r.p.m.     comjiound    wound    generator. 


72 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


mounted  on  a  common  base  with  and  directly  connected 
through  a  flexible  coupling  to  a  150  hp,  six-cylinder, 
water-cooled  gasoline  engine.  The  generator  has  stable 
operating  characteristics  and  ability  to  carry  the  heavy 
momentary  overloads  so  frequently  encountered  in  mo- 


FIG.    2 — 50   KW    I'ORT.Mil.K   POWER   PLANT 

tion  picture  service.  This  particular  generator,  nor- 
mally rated  at  400  amperes,  has  actually  carried  780 
amperes  for  18  minutes.  During  this  time,  it  was 
supplying  current  to  three  large  Sunlight  arcs,  one  30 
hp  motor  and  two  spotlight  arcs.  This  incident  oc- 
curred while  the  equipment  was  being  used  by  the  Fox 
Film  Company,  of  New  York,  for  location  work. 

The  engine  has  several  distinctive  features  which 
make  it  especially  adapted  to  this  service.  It  is  of  the 
water-cooled  type,  equipped  with  an  exceptionally  large 
^an  and  radiator.  An  impulse  coupling  on  the  magneto 
provides  a  very  quick  start.  The  coupling  connecting 
the  generator  and  engine  is  of  the  leather  disc  type  and 
is  welded  to  the  flywheel.  The  governor  is  exception- 
ally sensitive  and  is  adjusted  so  as  to  slightly  increase 
the  engine  speed  with  increase  in  load,  thereby,  aiding 
the  generator  in  maintaining  a  constant  voltage  at  all 
times,  which  is  an  essential  requirement  for  motion  pic- 
ture serviro. 


bolted.  This  construction  possesses  the  rigidity  of  cast 
iron  and  yet  it  is  considerably  lighter  in  weight. 

The  switchboard  for  the  control  of  the  generator 
and  feeder  circuits  is  securely  and  rigpidly  fastened  to 
the  steel  bedplate.  This  equipment  consists  of  two  400 
ampere  circuit  breakers,  three  200  ampere  fused  knife 
switches,  three  ammeters  for  the  three  feeder  circuits,  a 
voltmter,  and  a  knife  switch  for  an  incandescent  light-' 
ing  circuit.  The  three  large  rheostats,  conveniently 
located  at  the  side  of  the  engine,  regulate  the  current 
for  the  Sunlight  arcs  and  serve  as  ballasts  for  any  fluc- 
tuations in  the  current  caused  by  varj'ing  resistance  in 
the  arc  circuits. 

The  description  given  above  covers  a  complete 
power  plant,  which  is  mounted  on  a  large  automobile 
chassis  provided  with  a  specially-designed  body.  The 
truck  carries  a  reel  with  one  thousand  feet  of  flexible 
cable,  so  that  the  arcs  can  be  operated  at  a  considerable 
distance  from  the  power  plant.  Although  this  portable 
set  was  designed  especially  for  outdoor  motion  picture 


FIG.   3 — COMPLETE     DIRECT-CURRENT    GENERATING     EQUIPMENT     AND 
SUNLIGHT  ARC  REFLECTOR 

Special  attention  was  given  to  the  design  of  the 
bedplate.  In  order  to  keep  the  total  weight  of  the  set  a 
minimum,  and  at  the  same  time  provide  good  me- 
chanical construction,  the  bedplate  was  built  up  of  steel 
channels  and  angles.     All  joints  were  welded  instead  of 


FIGS.   4  AND   5—100000  CANDLE-POWER   SUNLIGHT   ARC 
ING  RESCUE  WORK  AT  NIGHT 

service,  there  will  doubtless  be  extensive  uses  of  this 
equipment  for  other  applications,  as  the  following  in- 
cident will  illustrate. 

On  December  ist,  1920,  a  large  apartment  house, 
located  at  52nd  Street  and  Broadway,  New  York  City, 
suddenly  collapsed,  burying  several  persons  underneath 
its  ruins.  This  happened  at  5  :oo  o'clock  in  the  after- 
noon. On  account  of  the  lack  of  daylight,  the  rescue 
work  proceeded  slowly  at  first  and  with  great  hazard  to 
the  workmen.  The  Fire  and  Police  Departments  re- 
sponded to  the  emergency  call,  but  were  unable  to  work 
to  advantage,  due  to  the  growing  darkness  and  possible 
danger  from  falling  girders  and  walls.  Within  an 
hour  after  the  accident  was  reported,  the  Sunlight  Arc 
Company  had  their  portable  generating  set  with  two 
100  000  candle-power  Sunlight  arcs  on  the  scene  of 
action.  One  lamp  was  stationed  on  a  truck  at  52nd 
Street  and  Broadway.  The  immense  beam  of  white 
light  from  this  lamp  illuminated  the  ruins  on  the  Broad- 


Februar}',   1921 


THE  ELECTRIC  JOURNAL 


7i 


way  side  and  part  of  the  adjacent  buildings  toward  53rd 
Street.  The  other  lamp  was  located  near  52nd  Street 
and  7th  Avenue  and  illuminated  the  side  of  the  ruins 
facing  S2nd  Street.  This  light  not  only  greatly  facili- 
tated the  rescue  work,  but  further  made  it  possible  for 
the  camera  men  to  secure  pictures  from  time  to  time 


during  the  course  of  the  night,  as  shown  in  Figs.  4  and 
5.  The  chiefs  of  the  New  York  Police  and  Fire  De- 
partments were  outspoken  in  their  praises  of  this  ap- 
paratus and  the  great  service  it  can  render  as  mani- 
fested on  this  occasion. 


Our  subscribers  are  invited  lo  use  this  department  as  a 
means  of  securing  authentic  information  on  eiectrical  and 
mechanical  subjects.  Questions  concerning  getieral  eneineer- 
ing  theory  or  practice  and  questions  regarding  apparatus  or 
materials  desired  for  particular  ne?ds  will  be  answered. 
Specific  data  regarding  design  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self-addressed,  stamped  en 
veiope  should  accompany  each  query.  All  data  necessary  for 
a  complete  understanding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
as  the  necessary  information  is  available;  however,  as  each 
queston  is  answered  by  an  expert  and  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


1962 — Pitting  of  Relay  Contacts — Will 
the  connections  shown  in  Fig.  (a) 
prove  satisfactory;  that  is,  will  the 
CR  relay  contacts  interrupt  the  cur- 
rent flowing  through  the  auxihary 
trip  coil  A  and  the  eight  candle-power 
lamps  without  excessive  burning  or 
pitting?  Or  must  the  connections 
shown  in  Fig,  (b)  be  used,  in  which 
an  au-xiliary  switch,  which  is  opened 
when  the  oil  switch  opens,  interrupts 
the  current  flowing  through  the  aux- 
iliary trip  coil  and  lamps.  It  is  real- 
ized that  the  auxiliary  switch  can  be 
adjusted  so  as  to  interrupt  the  cur- 
rent, thits  relieving  the  CR  relay  con- 
tacts of  this  duty,  but  is  the  addition 
of  an  au-xiliary  switch  and  the  re- 
quired   wiring    necessary? 

R.n.G.   (mont.) 

The    connections    shown   in    Fig.    (a) 

will    not    be    satisfactory,    except    under 

certain    conditions,     for    the     following 


Auxiliary  Sw _ 

Is  Closed  When  Oil 
Switch  IS  CInscd 


(c) 
FIGS.    1962    (a),    (b)    and    (c) 

reason.  All  CR  reverse  power  relays 
are  equipped  with  an  auxiliary  con- 
tactor, which  comes  into  action  when 
the  trip  current  exceeds  a  value  of 
approximately  two  amperes.  This  con- 
tactor   sHunts    the    main    relav    contacts 


and  is  so  arranged  that  when  it  is  once 
closed  it  will  remain  closed  until  the 
trip  circuit  is  broken  by  external  means 
such  as  a  pallet  switch  on  the  circuit 
breaker.  A  diagram  of  this  connection 
is  shown  in  Fig.  (c).  Therefore,  if  the 
current  is  equal  to  or  above  two  am- 
peres and  if  a  standard  relay  is  used, 
it  will  be  necessary  to  make  trip  con- 
nections as  shown  in  Fig.  (b)  or  the 
trip  circuit  will  not  be  broken.  The 
value  of  the  current  taken  in  this  case 
IS  not  given,  though  it  is  probably  not 
as  much  as  two  amperes.  Hence,  the 
contactor  will  not  come  into  action  and 
it  will  be  necessary  to  use  a  palUt 
switch  to  prevent  the  relay  contact-; 
from  breaking  the  trip  circuit.  Th'- 
relay  contacts  will  safely  close  thi^ 
current  but  repeated  breaking  will 
cause  damage  from  burning.  The  only 
case  in  which  it  would  be  safe  to  use 
this  relay  without  an  auxiliary  or  pallet 
switch  is  in  the  case  of  the  transfer 
relay  or  direct-trip  attachment,  where 
the  only  current  the  contacts  have  to 
handle  is  that  due  to  the  transformer 
action  in  the  teaser  coil.  e.a.h. 

1963 — Insulation  Resistance — Can  you 
give  me  the  resistances  in  ohms  or 
megohms  to  ground  required  in  manu- 
facturing electric  motors  for  the 
following  voltages:  no,  220,  440,  2200 
volts?  What  is  the  lowest  resistance 
permissible  for  a  rewound  motor? 

G.K.  (alberta) 
The  standardization  rules  of  the  A.  I. 
E.  E.  state  that  "The  insulation  resist- 
ance of  a  machine  at  its  operating 
temperature  shall  not  be  less  than  that 
given  by  the  following  formula : 
Insulation  resistance  in  megohms  :=n 

Voltage  at  terminals 

Rated  capacity  in  kv-a  -\-  1000 

From  this   formula  the  insulation   re- 
sistance for  motors  up  to  100  hp  should 
be  not  less  than — 
o.io  to  o.ii  megohms  for     no  volts 
0.20  to  0.22  megohms  for    220  volts 
0..40  to  0.44  megohms  for    440  volts 
2.0    to  2.2     megohms  for  2200  volts 
However,  the   insulation   resistance   is 
extremely  variable.      Different  tempera- 
tures and   different   degrees   of   dryness 
as    well    as    the    dirt   or    dust    that    has 
settled    on    the   windings   affect    the    in- 
sulation    resistance    greatly.      Induction 
motor  stators  for  no  to  2200  volts  up  to 
100    hp    will    usually    have    about     100 
megohms  insulation  resistance  when  new 
and   dry.     If  the  windings   are  not  dr\' 


they  may  measure  less  than  one  mcgi  hn- 
but  by  thoroughly  drying  they  usu.ii' 
reach  the  above  figure,  Direct-curre'i. 
armatures  on  account  of  the  creepage 
surface  of  the  commutators,  usually  have 
from  I  to  5  megohms  insulation  resist- 
ance when  new  and  dry,  j,L.i<. 

1964 — DivEKSiTY  Factor — Would  you 
kindly  explain  how  to  obtain  the 
diversity  factor  of  any  one  piece  of 
equipment,  lor  instance  that  of  a  mine 
hoist,  and  also  the  diversity  factor  of 
several  pieces  of  equipment  collec- 
tively, for  instance  air  compressor, 
haulage,  hoist,  pumping  and  lighting 
loads.     Give  an  e.xample  of  both  cases. 

A.W.    (.MINN.) 

The  expression  "diversity  factor"  is 
never  used  in  connection  with  a  single 
piece  of  power  equipment  or  small  group 
of  equipments  in  one  location.  F'or  a 
condition  of  this  kind,  the  expression 
"load  factor"  is  more  generally  applied. 
Load  factor  may  be  defined  as  the  ratio 
between  the  average  load  and  the  full 
capacity  of  the  equipment.  The  average 
load  is  obtained  bj'  means  of  a  watthour 
meter,  or  by  integrating  a  graphic  power 
curve.  The  load  factor  may  be  hourly, 
daily,  weekly,  monthly  or  yearly.  Di- 
versity factor  is  used  in  connection  with 
several  groups  of  equipment  which  may 
be  operated  at  separated  points,  but 
supplied  from  the  same  source  of  power. 
It  is  the  ratio  of  the  combined  peak 
loads  (momentan,'  or  integrated  time 
peaks)  to  the  total  sum  of  the  individual 
peak  loads.  Where  the  various  groups 
of  equipment  are  of  the  same  nature, 
the  diversity  factor  is  not  very  great. 
\\'here  the  type  of  load  for  the  various 
groups  is  entirely  different  the  diversity 
factor  may  be  quite  high.  A  high  di- 
versity factor  enables  a  central  station 
lo  take  care  of  a  number  of  group;  of 
apparatus  that  would  require  isolated 
plants  of  a  much  greater  combined 
capacity.  The  method  of  obtaining  the 
diversity  factor  is  to  take  the  load 
curves,  cither  estimated  or  from  graphic 
meters,  of  the  various  groups  of  appar- 
atus and  combine  these  cur\'es  to  obtain 
a  total  power  curve.  The  diversitv 
factor  is  obtained  by  determining  the 
peak  load  from  the  combined  curve  and 
taking  the  ratio  of  the  summation  of  the 
separate  peaks  from  each  group  of 
apparatus  to  this  combined  peak.  For 
an  example,  to  illustrate  load  f.nctor.  ler 
us  assume  that  a  power  plant  has  a 
capacity  of  looo  kw.  The  total  outmit 
in    kw-hours    per    day    is    15  000.     The 


74 


THE  ELECTRIC  JOURNAL 


Vol.  X\'III,  No.  2 


daily  load  factor  would  therefore  be 
15000  divided  by  24000  or  0.625,  or  62.5 
percent.  As  an  example  of  diversity 
factor,  assume  tlie  same  plant  is  fur- 
nishing power  to  four  groups  of  appar- 
atus :  a  mine,  a  quarry,  a  street  railway 
and  a  pumping  station.  The  15-minuto 
integrated  time  peak  is  350  for  the  mine, 
350  for  the  quarry,  400  for  the  railway 
and  300  for  the  pumping  station.  The 
total  sum  of  the  individual  groups  would 
give  a  peak  load  of  1400  kw.  However, 
due  to  the  fact  that  the  peaks  come  at 
different  times,  the  total  combined  peak 
would  be  about  1000  kw.  The  diversity 
factor  is,  therefore,  1.4  to  I.  G.B. 

1965  —  Synchronous  Converters  — ■ 
What  phenomenon  takes  place  in  a 
transmission  line  that  causes  syn- 
chronous converters  suddenly  to  re- 
verse their  direction  of  rotation? 
This  peculiar  change  takes  place 
either  during  or  immediately  follow- 
ing the  interruption  of  the  supply 
circuit  by  the  tripping  out  ot  a  mam 
oil  switch  some  where  in  the  system- 
The  above  condition  is  always  pre- 
ceded by  a  surge  or  kick.  Revers- 
ing of  the  rotation  of  the  armatures 
has  taken  place  in  five  substations  at 
one  time  or  another,  although  infre- 
quently. Four  substations  have  two 
converters  each  while  the  other  has 
but  one.  Whatever  occurs  affects 
only  one  machine  at  a  time.  After 
the  converter  stops  and  is  again  con- 
nected to  the  source  of  supply  it 
starts  off  in  the  right  direction  as 
though  nothing  had  happened.  Anoth- 
er peculiar  thing  that  has  come  under 
our  observation  is  the  over  speed- 
ing of  the  armature  immediately 
after  a  surge.  In  this  case  the  power 
is  not  interrupted.  The  transmission 
line  is  part  of  a  large  power  system 
at  60000  volts.  o.D.G.  (n.  y.) 
If   a  converter   flashes  over  during  a 

line  disturbance,  this  flash  short-cir- 
cuits all  the  commutator  bars  and  the 
short-circuit  armature  currents  set  up 
an  armature  reaction  in  the  same  man- 
ner as  in  a  polyphase  armature  winding 
when  it  is  short-circuited.  This  arma- 
ture reaction  is  momentarily  of  very 
heavy  strength  and  is  directly  demag- 
netizing in  its  reaction  on  the  main  field 
pole  flu.K.  In  some  converters  the  ar- 
mature reaction  may  greatly  reduce  or 
even  entirely  reverse  the  polarity  of 
the  main  field  flux  during  a  flash  over 
and  cause  either  an  overspeed  or  tem- 
porary rotation  in  reverse  direction.  .\ 
partial  flash  over  may  cause  overspeed 
without  the  rotary  converter  perman- 
ently falling  out  of  step,  while  in  case 
of  reversed  rotation,  the  rotary  con- 
verter always  finally  stops.  v.t.h. 

1966  —  Reversed  Current  in  Am- 
meter— Following  a  short-circuit  in 
the  pilot  lamp  of  an  exciter  supplying 
a  synchronous  motor,  I  find  that  the 
ammeter  is  reversed.  How  do  you  ac- 
count for  this  reversed  current? 
How  can  the  ammeter  be  made  to 
register    without   changing   its    leads? 

M.B.E,  (ore.") 
Without  more  information  in  regard 
to  the  type  of  exciter  and  the  troubles 
experienced,  we  cannot  definitely  ac- 
count for  the  reversed  current.  If  the 
exciter  were  a  non-commutating  jwle 
machine,  with  the  brushes  shifted  for- 
ward     i<ir     connnutnting      purjioses.      a 


short-circuit  on  the  e.xciter  leads 
would  cause  such  a  heavy  current  to 
flow  in  the  armature  circuit,  that  thf 
armature  reaction,  which  is  in  such  a 
direction  as  to  oppose  the  main  field 
flux,  might  overcome  the  main  field 
flux  and  thus  change  the  polarity  of 
the  generator.  This  would,  of  course, 
cause  the  ammeter  to  read  in  the  re- 
verse direction.  If  the  leads  are  to  be 
unchanged,  the  ammeter  can  only  be 
made  to  register  correctly  by  reversing 
the  polarity  of  the  generator,  so  that 
its  polarity  will  be  the  same  as  it  was 
originally.  To  do  this,  impress  a  sepa- 
rate source  of  direct  current  for  a  few- 
seconds  upon  the  shunt  field  circuit  in 
a  direction  opposite  to  that  in  which 
the  current  is  now  flowing.  This  will 
reverse  the  residual  magnetism  of  the 
fields  and  cause  the  exciter  to  build  up 
in  a  direction  such  that  the  ammeter 
will  read  correctly.  Also  if  the  exciter 
were  short-circuited  again  its  polarity 
would  be  reversed,  but  we  do  not  rec- 
ommend that  this  be  done.  c.l. 

1967 — Choke  Con,  Effect  of  Ar- 
moured Caw.e — Will  the  armour  of 
a  three-conductor  lead  covered  ar- 
mour protected  cable  act  as  a  choke 
coil    for    lightning   protection? 

R.H.L.  (n.c.) 
Any  cable  with  a  grounded  sheath 
receives  considerable  protection  from 
lightning  by  the  condenser  effect  of  the 
lead  sheath.  This  gives  Hust  the  op- 
posite effect  to  that  caused  by  the  in- 
ductance of  apparatus  windings.  The 
latter  piles  up  the  voltage  of  a  steep 
wave  front  or  high  freqiiency  surge 
and  increases  the  likelihood  of  insula- 
tion failure,  while  in  the  case  of  the 
cable  the  condenser  effect  of  the  sheath 
tends  to  bypass  the  surge  to  ground  and 
reduce  its  voltage  and  steepness.  It 
makes  little  difference,  however,  what 
the  material  of  the  sheath  may  be,  as 
the  magnetic  effect  of  an  iron  sheath 
is  very  small  to  sleep  wave  front 
surges.  U-AB. 

196S — Twin  Motor  Drive — In  small 
direct-current  hoists  up  to  two  hun- 
dred horse-power  if  the  increased 
first  cost  was  cancelled  bv  immunity 
from  total  break-down,  does  not  a 
twin  drive  adapt  itself  better  than  the 
sin.glc  larger  motor.  I  have  in  mind, 
particularly,  the  electrifying  of  steam 
geared  hoists.  The  single  motor  with 
its  large  pinion,  is  not  always  easy 
to  arrange  symmetricallv  with  the 
counter  shaft,  while  the  equivalent 
pair  of  smaller  motors  usually  can 
be.  j.G.n.    (r.AL.") 

"Tw'in  drive"  is  rather  misleading; 
"two  motor  drive' '  is  better.  Twin 
drive  would  apply  to  the  twin  motors 
as  used  in  the  Chicago,  Milwaukee  & 
St.  Paul  locomotives.  The  use  of  two 
motors  instead  of  a  single  motor  is 
frequently  desirable  on  hoist  drives.  It 
is  not  possible,  however,  to  say  that  all 
small  direct  current  hoists  up  to  200 
hp  would  be  better  driven  by  two  mo- 
tors instead  of  one  if  it  were  not  for 
first  cost,  as  there  are  a  great  many 
applications  where  the  use  of  two  mo- 
tors would  only  complicate  the  installa- 
tion without  gaining  any  advantage. 
Under  the  following  conditions  the  two 
motor  drive  will  be  preferable  to  the 
single  motor  and  as  a  general  proposi- 
tion will  justify  the  increased  cost  of 
motor  and  control  equipment.     The  fol- 


lowing applies  regardless  of  the  size  of 
the   equipment : 
a — Where     the     mechanical     arrange- 
ment on  the  hoist  is  such  that  in  a 
change      of      motive      power      less 
changes   will   be   necessary. 
b — Where  physical  limitations  due  to 
transportation    problems,   accessibil- 
ity,  or  space  available   for  installa- 
tion make  it  necessary  to  reduce  the 
size    and    weight    of    the    individual 
parts  to  a  minimum. 
c — Where  it  will  be  possible  to  oper- 
ate   at    reduced    capacity    with    one 
unit    in    case    of    accident    to    the 
other.   (This  will  not  always  be  the 
case,   as   in   a   great   many   hoisting 
installations,    particularly    with    un- 
balanced   operation    and    with    bal- 
ance operation  in  very  deep  shafts, 
one  motor   will   not   have   sufficient 
torque  to  handle  the  empty  cage  or 
skip.) 
d — Where   it   is   desirable   to   use   ser- 
ies parallel  control   in  order  to  cut 
down  power   peaks   in   starting  and 
in     the     handling    of     exceptionally 
heavy     loads     at     reduced     speeds. 
(This  applies  only  to  direct-current 
hoists,     while     a,     b     and     c     apply 
equally      to      alternating   -   current 
hoists). 
c — Wliere  it  is  desirable  that  the  in- 
ertia of   the   moving  parts  be   kept 
to   a   minimum    to   permit   of    rapid 
acceleration.      The     inertia     of     tlie 
revolving   parts   of    two    small   mo- 
tors will  generally  be  less  than  that 
of    the    equivalent    larger    motor. 
In    the    study    of    an    actual    problem 
several    of    the    above    factors    may    be 
present,   in   which   case   the   two   motor 
arrangement    would    doubtless    be    se- 
lected    but     unless     some     outweighing 
advantage  is  gained  it  is  generally  pref- 
erable to  stick  to  the  simpler  single  mo- 
tor drive.  R.w.M. 

1969 — Heating  of  Ikon  in  Alternator 
— Recently,  being  called  on  a  trouble 
job  on  a  no  kw  alternator,  with  a 
live  kw  exciter  I  found  that  the  iron 
of  the  alternator  got  hot  and  I  as- 
sumed this  to  be  oversaturation  of 
the  iron.  The  exciter  also  got  very 
hot  having  a  temperature  rise  of  40 
degrees  C.  after  one  hour's  run  with 
the  load  on  the  alternator.  We  could 
not  find  any  cause  for  the  heating  of 
the  e.xciter,  everything  seemed  to  be 
right,  still  the  exciter  Pfot  very  hot. 
The  power-factor  of  the  alternator 
was  80  per  cent.  We  did  not  have  a 
rheostat  in  series  with  the  field  coils 
on  the  rotor.  I  assumed  that  if  we 
had  a  rheostat  for  the  alternator  field 
coils  we  could  regulate  the  generator 
voltage  and  reduce  the  load.  Will 
you  kindly  let  me  know  if  my  as- 
sumption is  correct,  if  not,  kindly 
give   your   views   on   the   subject. 

w.s.  (n.  J.) 
The  only  effect  of  an  alternator  rheo- 
stat would  be  to  raise  the  exciter  volt- 
age and  possibly  increase  its  tempera- 
ture, assuming  that  the  alternator  is 
operating  alone.  It  would  have  no  ef- 
fect on  the  alternator  unless  the  alter- 
nator is  operating  in  parallel  with  other 
machines  and  the  exciter  voltage  is 
now  higher  than  it  should  be.  In  that 
event  the  armature  and  field  currents 
of  the  alternator  and  voltage  of  the  ex- 
citer could  be  reduced  by  adding  an 
alternator   rheostat.  ph. 


February,   1 92 1 


THE   ELECTRIC  JOURNAL 


75 


1970 — Grounding  of  Stator  Coils  —  I 
am  having  trouble  with  a  75  hp, 
three-phase,  60-cycle,  440  volt,  720 
r.p.m.  slip  ring  motor.  I  have  wound 
this  motor  and  have  taken  unusual 
precautions  in  winding  it.  With  all 
the  precautions  this  motor  breaks 
down  to  ground  at  times.  It  has  a 
voltage  test  to  ground  of  2200  volts. 
The  other  day  one  of  the  coils 
grounded  in  spite  of  the  fact  that  it 
has  been  in  service  not  over  three 
months.  It  received  the  usual  in- 
sulating paint,  and  in  addition  I  put 
on  a  heavy  coat  of  weather-proof 
varnish.  It  has  a  good  clearance  be- 
tween rotor  and  stator,  does  not  pull 
any  over  load,  its  running  load  is  45 
to  55  amperes  per  phase.  The  mo- 
tor is  used  in  a  glass  manufacturing 
plant  to  rotate  a  mammoth  drum  on 
gear  wheels  with  a  chain  drive.  The 
gear  wheels  revolve  this  drum,  which 
weighs  from  55  to  65  tons.  The 
drum  contains  liquid  glass.  The  con- 
dition under  which  it  works  is  this. 
.\s  this  drum  revolves  it  carries  the 
liquid  glass  up  the  sides  of  the  drum, 
and  when  the  contents  let  go  it  car- 
ries the  drum  forward  faster  than 
the  torque  of  the  motor  revolves  it. 
Of  course  this  is  on  only  one  spot 
of  the  revolution.  There  is  also  a 
large  amount  of  vibration,  due,  of 
course,  to  the  liquid  glass  slipping  off 
the  sides  of  the  drum.  The  second- 
ary resistance  is  O.  K.  and  there  arc 
no  open  leads.  The  voltage  is  good, 
being  460  at  one  board  from  2300 
volt  primary.  Am  I  correct  in  as- 
suming that  the  carrying  forward  of 
the  rotor  faster  at  times  by  the  drum 
than  the  torque  would  revolve  it,  has 
a  tendency  to  puncture  the  insula- 
tion? This  last  ground  I  have  not 
examined  because  I  cut  out  this  coil 
in  order  that  we  might  continue  op- 
eration. But  previous  to  this  the  coils 
showed  a  clear  burn  off  of  the  insula- 
tion of  three  coils  at  the  diamond 
turns  or  rather  half  way  between  the 
end  turn  and  the  laminations.  The 
conductors  are  of  standard  square 
wire  used  for  75  hp  motors.  The 
motor  is  protected  by  a  circuit 
breaker  which  is  equipped  with  no 
voltage  and  under  voltage  trip  coils, 
and    it   works   properly.         c.c.  (n.j.) 

We  see  nothing  in  the  nature  of  the 
torque  conditions  that  should  cause  the 
motor  to  break  down,  but  the  informa- 
tion given  would  indicate  that  the 
trouble  is  due  to  the  vibration  of  the 
motor.  We  would  suggest  that  a  flexi- 
ble coupHng  be  placed  between  the  mo- 
tor and  the  gear  of  a  type  that  will  ef- 
fectively eliminate  the  shock  and  vibra- 
tion which  presumably  is  now  imposed 
upon  the  motor.  Overspeed  might  cause 
mechanical  chafing  of  the  insulation  on 
the  rotor.  s..\.s. 

1971 — Electrolyte  for  Chemic.^l  Rec- 
tifier— If  you  know  any  solution  that 
can  be  used  as  an  electrolyte  for  a 
rectifier,  kindly  let  me  know.  I  have 
found  ammonium  phosphate  pretty 
good,  but  I  would  like  to  get 
something  still  better.  It  must  not 
attack  iron,  as  I  want  to  use  it  in  an 
iron  jar.  I  thought  that  the  solution 
used  in  the  lightning  arrester  de- 
scribed in  the  June  issue  of  the  JouR- 
n.^l  might  do  the  trick. 

t.m.s.   (c.^l.  ) 


We  suggest  that  ammonium  citrate  be 
used  with  about  25  grams  of  ammonium 
citrate  per  litre  of  distilled  water,  li 
you  desire  to  use  electrolyte  such  as 
used  in  electrolytic  .  arresters,  you 
should  order  this  from  the  manufac- 
turers. However,  you  will  find  that  the 
ammonium  citrate  and  ammonium 
phosphate  solutions  will  give  you  far 
better  results  than  the  electrolyte  used 
with    electrolytic    lightning    arresters. 

G.C.D. 

1972 — Unst.\ble  Speed  of  Direct-Cur- 
rent Motor — We  have  several  five  hp, 
220-volt,  4C0  to  1800  r.p.m.  direct-cur- 
rent adjustable  speed  motors  equipped 
with  reverse  controller.  The  motors 
have  commutating  poles,  shunt  coils 
and  compensating  coils  in  slots  in  the 
face  of  main  poles.  The  motors  op- 
erate properly  in  botn  directions  up 
to  a  point  about  three  field  steps  from 
the  last  point.  They  operate  O.  K., 
running  clockwise  on  me  last  point, 
having  two  40  watt  220  volt  lamps  in 
series  with  field  resistance.  In  the 
counter  clockwise  direction  the  speed 
of  the  motor  is  stable  while  running 
on  the  third  point  from  last ;  but 
when  advanced  to  the  next  point  the 
speed  will  rise  and  fall,  causing  bad 
sparking  across  the  brushes.  The 
surging  gradually  becomes  of  longer 
periods  with  increased  sparkin,g.  The 
bruslics  were  on  the  fixed  factory 
position,  and  shifting  them  did  not 
help  to  improve  the  conditions  any. 
The  motor  was  tried  with  compen- 
sating coils  cut  out,  with  commutat- 
ing poles  reversed,  with  armature  re- 
versed and  with  compensating  coils 
reversed ;  but  no  improvement  re- 
sulted. We  had  no  meters  to  take 
readings  by  running  the  motor  as  a 
generator.  Would  you  please  advise 
me  how  to  get  these  motors  to  oper- 
ate properly.  j.e.m.   (mich.) 

-Ml  imperfectly  compensated  direct- 
current  shunt  motors  have  a  tendency 
toward  instability.  This  tendency  is 
partially  or  entirely  neutralized  by  the 
effect  of  the  resistance  drop  in  the  mo- 
tor. If  not  entirely  neutralized,  to 
make  the  motor  perfectly  stable  it  is 
necessary  to  shift  the  brushes  from  me- 
chanical neutral  forward  in  the  direc- 
tion of  rotation,  or  else  to  put  an  ad- 
ditive series  winding  on  the  fields.  If 
this  effect  is  secured  by  brush  shift  it 
docs  good  in  one  direction  of  rotation 
only  and  makes  the  motor  more  un- 
stable in  the  other  direction.  Small 
compensated  motors  are  usually  very 
imperfectly  compensated.  In  this  case, 
from  the  fact  that  sparking  occurred, 
and  that  the  motor  was  unstable  for 
one  direction  of  operation  only,  it 
seems  that  the  brushes  w-ere  shifted  off 
neutral  to  get  stability.  Put  the 
brushes  on  neutral.  To  do  this  run  the 
motor  in  each  direction  of  rotation  at 
the  same  load,  with  the  same  shunt  field 
amperes,  and  at  the  hiehest  speed  at 
which  it  is  stable,  and  shift  the  brushes 
till  the  speeds  under  these  conditions 
are  practically  the  same  in  both  direc- 
tions. Then  see  if,  with  this  brush 
position  the  motor  is  stable  over  the  full 
speed  range  and  in  both  directions  of 
rotation.  If  this  has  not  corrected  the 
trouble  it  will  be  necessary  to  put  a  few 
series  turns  on  each  of  the  main  poles. 
These  series  turns  should  be  connected 
additive  and  in  such  a  way  that,  when 


the  direction  of  current  through  the 
armature  is  reversed  at  the  reversal  of 
rotation,  the  direction  of  current 
through  the   series   field  is  unchanged. 

-M.S.H. 

1973— Exploring  Coil— I  have  to  locate 
a  network  of  underground  water 
mains  and  steam  nine  rrturns,  and 
want  to  make  up  some  kind  of  an  in- 
ductive locator.  I  do  not  want  to 
apply  the  commercial  alternating  cur- 
rent through  the  transformer  to  two 
sections  of  the  pipe  because  I  will 
get  a  sound  in  the  exploring  coil 
whenever  I  am  near  a  transmission 
line  and  this  method  will  not  help  me 
in  locating  the  pipe.  Can  you  tell  me 
about  the  design  of  an  exploring  coil 
and  some  kind  of  a  vibrator  to  oper- 
ate on  a  storage  cell  to  use  for  this 
work?  L.A.B.   (n.j.) 

We  presume  that  you  have  in  mind 
passing  an  alternating  or  pulsating  cur- 
rent through  the  pipes  and  locating 
them  by  means  of  an  exploring  coil 
connected  to  a  telephone  receiver.  Un- 
less your  pipes  arc  very  close  to  the 
surface  a  considerable  current  will  be 
necessary  to  give  reliable  results  in 
your  detector.  An  interrupter  operat- 
ing with  large  current  from  a  storage 
battery  would  be  very  hard  to  construct 
unless  operating  at  very  low  frequen- 
cies. However,  it  is  possible  that  with 
low  frequency  the  successive  clicks  in 
the  telephone  due  to  opening  and  clos- 
ing the  direct-current  circuit  might  en- 
able you  to  locate  the  pipes.  It  seems 
to  us  that  a  more  satisfactory  method 
would  be  to  use  a  transformer  giving  a 
fairly  large  secondary  current  the  pri- 
mary of  which  is  connected  to  a  com- 
mercial supply  line  through  a  circuit 
breaker.  If  now  the  circuit  breaker  is 
opened  and  closed  automatically  every 
few  seconds  the  field  due  to  the  test- 
ing circuit  could  readily  be  distin- 
guished from  that  produced  by  the 
power  lines  in  the  vicinity.  For  an  ex- 
ploring coil  use  one  having  a  large  num- 
ber of  turns  and  not  too  small  a  cross 
section.  The  larger  tne  number  of 
turns  and  the  greater  the  cross  section 
the  greater  the  sensibility  provided  the 
resistance  is  not  excessive.  In  order 
to  obtain  the  maximum  inductance  for 
a  given  size  and  length  of  wire  the  coil 
should  have  the  following  relative  di- 
mensions :  inside  raduis  1  ;  outside  ra- 
dius 2 ;  a.xial  length  0.3.  T.s. 

1974— Capacity  of  Air  Pump — What 
method  is  used  in  determining  the 
volume  of  air  passing  through  a  cen- 
trifugal hydraulic  air  pump;  for  ex- 
ample, a  Westinghouse — LeBlanc  ro- 
tary air  pump  connected  to  a  25  000 
sq.  ft.  surface  condenser  and  rated 
at  20  cu.  ft.  per  second  at  the  pressure 
prevailing  in  the  pump.  How  can  the 
performance  of  this  pump  be  checked 
under  working  conditions. 

P.M.J,  (n.  y.I 
The  method  normally  used  is  that  of 
blanking  off  the  air  suction  and  apply- 
ing a  calibrated  orifice.  The  rating  of 
20  cu.  ft.  is  that  of  rare  air  at  an  air 
pressure  of  approximately  0.75  in.  mer- 
cury. With  the  air  pump  water  having 
a  temperature  of  seventy  degrees,  this 
would  mean,  basing  the  air  pump  on  an 
absolute  pressure  in  the  air  line  of  ap- 
pro.ximatcly  1.5  inches  mercury.  This 
would  mean  the  use  of  an  orifice  ap- 
proximately 5^   inch  diameter.  c.s. 


76 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  2 


THE 
ELECTRIC 
JOURNAL 


)    purpose    of    this    section    is    to    present 
epted  practical  methods  used  by  operating 
companies    throughout    the    country 


The   co-operation   of  all   those   interested   in 

operating  and  maintaining  railway  equipment 

IS    invited.      Address    R.    O.    D.    Editor. 


FEBRUARY 
1921 


The  Handling  of  Copper 


Copper  cannot  be  given  the  same  rough  treatment  that 
iron  or  steel  or  brass  will  stand,  but  requires  some  important 
precautions  in  its  handling  and  application.  It  fails  quickly 
under  localized  stresses.  Sharp  bends,  rough  or  nicked  edges 
in  copper  straps  or  wires,  limited  movement  to  take  care  of  ex- 
pansion and  contraction,  are  all  points  especially  to  be  guarded 
against.  This  is  particularly  true  when  the  copper  is  subject 
to  quick  sharp  blows  or  vibration,  such  as  are  common  with 
railway  motors. 

BENDING  OP  COPPER 
All  bends  in  copper  should  be  made  free  and  easy,  that  is, 
they  should  be  given  as  large  a  curvature  as  is  possible  in  the 
space  available.  Where  sharp  bends  and  sharp  fillets  are  made 
the  eltects  of  vibration,  expansion  and  contraction,  or  the 
throwing  out  forces  due  to  rotation  show  up  first. 

Frequently  sharp  bends  are  made,  at  the  ends  of  coppei 
strap  field  coils,  when  making  the  clamped  or  soldered  joints, 
in  many  cases  the  bad  conditions  that  have  been  set  up  arc 
overlooked.  The  sharp  bend  or  kink  may  later  be  the  cause-  of 
a  motor  failure  which  could  have  easily  been  avoidea.  It  often 
happens  that  the  armature  coil  failure  is  at  a  point  where  the 
wires  have  been  carelessly  bent  or  crossed. 
NICKING  OP  COPPER 
The  nicking  of  copper  is  another  kind  of  abusive  practice 
to  be  avoided.  It  is  very  easy  to  nick  copper  with  the  sharp 
edge  of  a  metal  drift  or  on  other  tools  such  as  arc  used  in  con- 
nection with  the  winding  of  armatures.  It  is  preferable  to  use 
a  hard  fibre  drift  and  drive  leads  down  into  commutator  neck 
slot  by  using  a  copper  filling  piece  placed  on  the  lead  to  receive 
the  blow  from  the  hammer,  .'\uother  source  of  trouble  due  to 
nicking  of  copper  is  found  in  field  coil  cable  leads  breaking  at 
the  point  where  the  insulation  has  been  cut  off  with  a  knife, 
the  break  having  been  started  by  the  knife  nicking  the  strands 
of  the  cable.  Such  nicks  are  the  starting  point  of  breaks,  as 
surely  as  are  those  which  the  glazier  cuts  in  glass  when  he  is 
cutting  it  for  the  window  pane.  Extreme  care  should  be  used 
in  removing  insulation  on  all  cables  and  wires  of  small  cross- 
sections. 

EXPANSION  AND  CONTRA.OTION 
For  the  same  temperature  a  piece  of  copper  will  expand 
more  than  a  similar  piece  of  iron  or  steel.  Further,  it  is 
usually  found  that,  in  a  motor,  the  copper  becomes  hotter  than 
the  other  materials  of  which  the  motor  is  made.  Therefore,  it 
is  necessary  to  provide  means  for  the  copper  to  expand  and 
contract  to'take  care  of  the  relative  motion  between  the  differ- 
ent materials  for  the  changes  in  temperature.  A  common  error 
in  this  respect  is  to  anchor  wiring  around  the  frame  connec- 
tions or  to  the  frame  proper  when  it  should  have  been  securely 
bound  to  the  windings,  so  that  it  would  be  free  to  move  with 
the  windings.  It  is  obvious  that  this  is  more  important  with 
solid  strap  conductors  than  with  flexible  cables. 
CLEATING  AND  SUPPORTING 
Properly  supported  copper  stands  up  well  against  vibra- 
tion. In  fact,  one  finds  it  extensively  used  in  certain  applica- 
tions where  vibration  occurs,  because  of  its  good  behavior  in 
this  respect.  But  improperly  supported,  copper  fails  miserably 
under  vibration.  This  point  is  frequently  ignored  in  connect- 
ing car  wiring  cables  to  the  motor  leads  when  cleats  are  not 
applied.  Care  should  be  observed  to  study  this  point  with  the 
purpose  of  properlv  locating  the  cleats  in  supporting  the  cables. 
It  often  happens  that  the  weight  of  a  solid  connector^  even 
though  it  mav  look  rather  small  is  sufficient  under  vibration  lo 
cause  the  copper  strap  or  stranded  cable  to  break  at  a  point 
just  behind  the  connector  where  stresses  are  localized. 
TINNING  STRANDED  COPPER  BETOND  SUPPORT 
Just  here  also  must  be  emphasized  the  bad  effects  of  tin- 
ning' stranded  copper  beyond  the  point  where  the  joint  is  made. 
Thus,  for  example,  instead  of  coming  right  out  through  the 
end  of  the  connector,  the  solder  should  stop  just  inside  the 
connector  so  that  the  stresses  will  not  localize  on  the  strands 
where  the  tinning  stops  and  where  the  strands  are  not  sup- 
ported against  vibration. 


SICKNESS  OF  COPPER 
Copper  is  subject  to  a  form  of  sickness  which  so  far  as 
has  been  experienced  is  peculiar  to  copper  alone.  This  subject 
has  been  thoroughly  discussed  by  Mr.  i^iling*.  All  commercial 
copper  contains  a  small  amount  ot  o.xygen  in  the  form  o£ 
copper  oxide,  without  which  it  has  poor  mechanical  character- 
istics. When  it  is  heated  in  a  flame  which  is  rich  in  free  hy- 
drogen, this  hydrogen  unites  with  o.xygen  forming  free  copper 
and  steam.  It  is  a  peculiar  characteristic  that  the  hydrogen 
will  readily  enter  the  hot  copper,  but  the  steam  cannot  get  out. 
The  copper  is  thus  not  only  weakened  by  the  elimination  of 
the  copper  oxide,  but  the  high  pressure  steam  expands,  pro- 
ducing a  spongy  effect  which  still  further  weakens  the  copper. 
This  effect  is,  of  course,  greatest  near  the  surface.  This 
peculiar  form  of  sickness  should  be  guarded  against  by  the  op- 
erating men.  An  experience  in  connection  with  some  failures 
on  copper,  which  occurred  due  to  this  change  in  siruCture,  wiH 
serve  to  bring  out  this  lesson. 

AN  EXPERIENCE  IN  THIS  SICKNESS  OP  COPPER 
An  armature  was  being  wound  with  coils  having  nickel 
silver  resistance  leads,  with  copper  tips  brazed  onto  their  ends. 
.\  number  of  coils  had  been  put  in  place  when  it  was  found 
that  the  first  one  had  to  be  removed.  In  doing  this, 
the  copper  tips  were  bent  back  to  get  them  out  of  the  way. 
W  ih  only  a  single  bend  one  of  the  tips  broke  off  in  the  work- 
man's hands.  On  examining  all  the  tips  of  the  coils,  twelve 
more  defective  ones  were  found.  At  first  it  was  tnouglit  that 
it  was  a  bad  lot  of  copper.  Tests  showed  that  the  copper, 
from  which  the  tips  were  made,  was  of  good  quality.  A  study 
of  the  process  of  handling  the  copper  revealed  that  the  defec- 
tive tips  had  been  heated  in  a  llame  containing  unburned  hy- 
drogen. 

Since  one  cannot  see,  without  breaking  the  strap  or  wire, 
whether  the  copper  has  been  affected  by  the  sickness,  it  fol- 
lows, that  to  be  safe,  copper  should  not  be  heated  in  a  flame 
containing  an  excess  of  hydrogen.  This  means  that  with  a 
blow  torch  the  copper  should  be  kept  outside  of  the  inner  cone 
of  blue  flame.  When  heating  copper  in  a  gas  and  air  furnace, 
an  excess  amount  of  air  should  always  be  used,  as  too  little 
air  will  produce  an  excess  of  free  hydrogen.  Smoke  from  such 
a  furnace  always  indicates  too  little  air  and  the  mixer  should 
be  adjusted  to  give  a  little  more  air  than  is  necessary  to  pre- 
vent any  trace  of  smoke.  Wherever  possible  the  copper 
should  be  heated  without  coming  into  direct  contact  with  the 
flame. 

CLEANING  INSULATION  FROM  COILS 
It  has  been  common  practice  to  burn  the  insulation  from 
old  coils.  This  should  not  be  done  where  the  coils  are  to  be 
reinsulated  and  used  again.  The  question  then  comes;  how  are 
we  going  to  remove  the  old  insulation?  One  big  operator 
places  the  coils  in  an  oven  and  passes  steam  through  the  coils 
for  12  or  14  hours.  He  finds  that  the  insulation  peals  off 
easily  while  hot.  Another  operator  dips  the  coils  in  a 
weak  solution  of  muriatic  acid  for  a  time  (approxi- 
mutely  24  hours)  so  that  the  acid  weakens  the  insulation, 
Init  not  long  enough  to  give  the  acid  a  chance  to 
cat  into  the  copper.  The  nccessarj'  time  required  can  easily  be 
established  bv  checking  carefully  and  removing  the  coil  when 
the  brightening  of  copper  commences.  After  the  acid  rrcat- 
ment,  the  coils  should  he  thoroughly  washed  in  clear  water. 
SUMMARY  OF  PRECAUTIONS 
]_Avoid  sharp  fillets  and  kinks  as  well  as  bends  of  small 

radii.  . 

o_Do  not  nick  copper  under  any  condition. 
3— Remember  that  this  metal  will  expand  and  contract  in 

service.  .  ... 

4_Provide  proper  supports  against  vibration. 
5 — Use  extreme  care  in  tinning  cables. 
6— Avoid  heating  the  metal  in  a  flame.  J.  V.  DonSON 


•In  the  Journal  for  August,  1920,  p.  320. 


The  Electric  Journal 


VOL.   XVIll 


March.  1921 


No.  3 


The    paper   iiulustr)'    ranks    with    the 
greatest  industries  of  the  country ;  it 
Electric  Paper     ^t^^,-,^!^    jj^th    in    the    value    of   the 
Machine  annual    product    and    in    capital    in- 

vested and  probably  fourth  in  pri- 
mary horsepower  installed.  It  is  esti- 
mated that  for  1920  there  were  iioooo  persons  engaged 
in  the  manufacture  of  paper  in  this  countiy.  The 
capital  invested  was  approximately  nine  hundred  million 
dollars  and  the  value  of  the  product  was  approximately 
eight  hundred  fifty  million  dollars. 

During  the  war  period,  it  was  practically  impossible 
for  the  paper  mills  to  improve  their  plants  or  expand 
them ;  practically  no  progress  was  made  in  the  industry. 
As  a  result,  the  post-war  boom  of  1919  was  encountered 
with  mills  badly  in  need  of  improvements  and  inade- 
quate in  number.  During  the  last  two  years  much  has 
been  done  to  improve  this  condition,  and  a  great  deal 
of  interest  and  attention  is  being  given  to  the  subject  of 
greater  economies,  which  are  made  possible  by  further 
electrification  of  the  manufacturing  processes. 

The  most  important  recent  improvement  in  this 
industry  is  the  electrification  of  the  paper  machine, 
using  sectional  individual  motor  drive  with  automati- 
cally controlled  speed  regulation.  The  paper  machine  is 
the  fabricating  element  of  a  paper  mill  and  presents 
problems  of  drive  which  are  very  complex.  This  unit 
is  a  group  of  mechanically  independent  parts  covering 
considerable  space.  A  wide  range  in  speeds  is  required 
for  dififerent  kinds  and  grades  of  paper  and  it  is  neces- 
sary to  operate  the  sections  at  slightly  different  speeds. 
Extremely  close  speed  regulation  is  essentia!  under  all 
operating  conditions. 

For  years  paper  manufacturers  have  realized  the 
disadvantages  and  limitations  of  line  shaft  and  rope 
drive  and  have  hoped  for  their  elimination  by  the  de- 
velopment of  a  successful  system  of  sectional  individual 
motor  drive.  A  few  installations  of  multiple  motor 
drive  were  made  ten  or  twelve  years  ago,  but  with  only 
partial  success.  It  was  found  practically  impossible  to 
obtain  the  same  characteristics  in  the  different  motors, 
and  to  maintain  the  proper  speeds  of  the  paper  machine 
sections  both  personal  attention  and  objectionable  hand 
operation  of  field  rheostats  were  required. 

All   line    shafts,   spur  and   bevel   gears,   belts   and 


pulleys  transmitting  [jower,  in  fact  ail  of  the  un- 
economical and  unreliable  parts  of  the  older  forms  of 
drive  should  be  eliminated  by  sectional  motor  drive.  To 
be  of  the  greatest  benefit  to  the  paper  industry,  the 
drive  should  be  suitable  and  successful  for  all  kinds  of 
paper  machines,  either  high  speed  news  machines, 
medium  speed  book  or  specialty  machines,  or  slow- 
speed  board  machines. 

The  system  of  sectional  individual  motor  drive  and 
control  described  by  Mr.  Staege  in  this  issue  of  the 
Journal  is  the  result  of  years  of  engineering  experience 
and  study  of  the  problems  of  paper  machine  drive.  As 
compared  with  other  systems  which  have  been  devised, 
this  drive  has  several  superior  features,  namely,  it 
eliminates  all  of  the  undesirable  features  of  the  older 
types  of  drive  and  is  equally  applicable  to  all  kinds  of 
paper  machines. 

The  section  motors  of  this  system  may  be  direct 
connected  or  geared  to  the  paper  machine  shafts.  The 
method  of  connection  is  optional  on  medium  and  high- 
speed paper  machines;  on  slow  speed  board  machines, 
direct-connected  motors  are  impracticable.  To  deter- 
mine the  most  suitable  type  of  driving  unit,  each  in- 
stallation must  be  carefully  analyzed  from  the  stand- 
point of  cost  and  efficiency. 

The  control  is  entirely  automatic  in  nature,  requir- 
ing no  operating  attention  other  than  the  usual  care 
given  to  any  ordinary  electrical  apparatus.  Electrical 
automatic  control  equipment  is  far  past  the  experi- 
mental stage  and,  because  it  eliminates  the  personal  ele- 
ment, it  is  more  reliable  than  hand  operation. 

An  installation  of  this  system  of  sectional  drive  and 
automatic  control  has  been  in  operation  for  about  a  year 
and  a  half  in  the  plant  of  the  Gould  Paper  Company, 
Lyons  Falls,  New  York,  on  a  148  inch  newspaper  ma- 
chine. During  this  time  no  interruptions  in  service 
have  been  caused  by  the  failure  of  the  regulating  equip- 
ment to  function  properly.  The  management  of  the  mill 
and  the  machine  operators  have  only  satisfaction  and 
commendation  to  express  for  the  successful  operation 
and  the  beneficial  results  it  affords.  A  number  of 
complete  installations  of  sectional  motor  drive  and  auto- 
matic control  on  several  different  types  of  paper  ma- 
chines will  be  in  operation  in  the  near  future. 

W.  H.  Artz 


:0:iiiadc  ^oood  lyOjicvc)!  xoc  ^octional 


\^i'* 


SIKPIIKN  A.  MAlA.I. 

Gcnoral   Eiigiiittr 

Westinghouse  Electric  &  Mfg.   Company 


PAPER  is  made  from  a  pulp  stock,  consisting  of 
cellulose  fibers  carried  in  suspension  in  water. 
It  is  transformed  from  this  liquid  mass  into  a 
smooth  sheet  of  paper  in  one  continuous  operation  on 
the  "paper  machine",  which  is  the  largest  and  most 
complex  of  the  various  pieces  of  apparatus  used  in  the 
manufacture  of  paper  from  the  raw  material.  W  hile 
differing  in  size,  these  machines  are  usually  several 
hundred  feet  long,  weigh  hundreds  of  tons  and  fre- 
quently cost  several  hundred  thousand  dollars. 

The  paper  is  formed  on  a  wire  screen  upon  which 
the  pulp  solution  is  evenly  deposited.  Part  of  the 
water  gravitates  through  the  wire  screen,  part  is 
drawn  through  the  screen  by  vacuum  suction  ho.xes  and 
still  more  is  re- 
moved by  t  h  e 
passage  of  the 
semi-formed  sheet 
between  large 
press  rolls.  Fi- 
nally, after  most 
of  the  water  has 
been  removed  in 
this  manner,  the 
paper  sheet,  now 
thoroughly  fabri- 
cated, passes  on- 
to large  revolving 
drying  cylinders 
heated  by  steam, 
where  nearly  all 
of  the  remaining 
moisture  is  evap- 
orated.  From  the 


card  boards,  container  boards,  box  boards,  etc.  In  the 
Fourdrinier  machine,  the  sheet  is  formed  on  a  wide 
wire  screen  operating  like  a  belt  around  two  rolls,  and 
driven  by  one  of  them  called  the  couch  roll,  the  pulp 
stock  solution  being  deposited  evenly  upon  the  surface 
of  this  wire  screen.  In  the  case  of  the  cylinder  ma- 
chine, the  liquid  pulp  stock  is  deposited  Bpon  the  sur- 
face of  a  revolving  screen  drum  or  in  many  cases  upon 
a  number  of  these  revolving  screens  known  as  cylinder 
moulds,  each  of  which  adds  a  thin  layer  of  pulp  stock 
to  a  revolving  felt,  making  a  sheet  of  any  desired  thick- 
ness. The  fundamental  difference  between  the  Four- 
drinier machine  and  ihe  cylinder  machine  is  that,  in  the 
Fourdrinier   machine,    the    sheet    is    formed    upon    the 

screen,  called  the 
Fourdrinier  wire, 
whereas  in  the 
'  \  lindcr  machine 
!.i  sheet  is  form- 
1  on  the  cylinder 
1  o  u  1  d  s.  The 
presses,  dryers 
and  calenders  are 
similar  in  both 
machines.  On  ac- 
ennnt  of  the  high- 
er speeds  at  which 
I'ourdrinier  ma- 
chines operate, 
m  a  n  y  variations 
in  mechanical  de- 
sign are  found  in 
the  two  general 
types  of  m a- 
chines. 


Fin.    I— 148     INCH     FOURDRINIER     MACHINE     FOR    M.^KING    NF.WS  PAPER 

Equipped    with    individual    motor    drive,  using     Westinghou.ie    automatic    sprcd 
.     .             ,.     ,          regulating  system, 
drying   cylinders, 

the  sheet  passes  to  the  calendar  stack  where  it  is  ironed  When   passing  between   the   press   rolls,  the   thin, 

out  to  a  glossy  hard  smoothness  by  its  passage  between  wet  sheet  is  slightly  elongated  and  in  its  passage  be- 

numerous  highly  polished  steel  rolls,  stacked  one  above  tween  presses  it  is  acted  upon  to  a  certain  extent  by  the 

the  other,  around  each  of  which  the  paper  is  threaded,  atmosphere,    causing   evaporation   and   a   tendency    to- 


After  leaving  the  calender  the  paper  is  wound  into  a 
large  roll  on  a  reel.  It  is  later  trimmed  to  the  desired 
width  and  rewound  into  new  rolls  of  the  dimensions  re- 
quired for  the  ultimate  user. 

Paper  machines  are  divided  into  two  principal 
types,  known  as  Fourdrinier  machines  and  cylinder  ma- 
chines. The  Fourdrinier  machines  are  used  chiefly  for 
the  lighter  weights  and  thicknesses  of  paper,  such  as 
news  print  paper,  book  paper,  etc.,  and  usually  operate 


wards  shrinkage.  This  is  also  true  in  the  passage  of 
the  sheet  from  the  last  press  to  the  dr}'er  rolls  and 
through  the  drj'er  rolls  to  the  calenders.  On  this  ac- 
count, it  is  necessary  that  the  paper  machine  be  so  con- 
structed that  each  of  its  component  parts  or  units,  that 
is,  each  of  its  press  rolls,  trains  of  dryer  rolls  and  stacks 
of  calender  rolls  can  be  operated  at  a  slightly  differ- 
ent speed,  in  order  to  compensate  for  the  variations  in 


at  relatively  high  speed,  whereas  the  cylinder  machines     the  elongation  or  shrinkage  of  the  sheet  that  may  take 
used  almost  exclusively  for  heavy  papers,  such  as      place  from  time  to  time,  due  to  changes  in  atmospheric 


March,  1921 


THE  ELECTRIC  JOURNAL 


79 


conditions  or  to  variations  in  the  consistency  of  the  pulp 
stock  as  it  is  fed  onto  the  machine. 

From  this  brief  description  of  the  paper  machine, 
it  will  be  seen  that  each  section  must  be  susceptible  to 
individual  speed  adjustment  and  control.  Moreover, 
the  correct  relative  speeds  of  each  of  the  sections  must 
be  maintained  with  great  precision,  or  the  paper  sheet 
will  quickly  be  broken. 

The  speed  at  which  paper  machines  operate  also 
varies  greatly.  In  cylinder  machines,  the  linear  speed 
of  the  paper  may  be  only  a  few  inches  or  feet  per 
minute  or  it  may  be  two  or  three  hundred  feet  per 
minute.  The  machines  will  vary  in  width  from  those 
which  can  produce  a  sheet  of  paper  3  or  4  feet  wide 
to  those  which  can  produce  a  sheet  10  or  15  feet  wide. 
Sometimes  a  single  machine  may  be  required  to  oper- 
ate over  a  great  range  of  speeds,  varying  from  perhaps 
ro  or  15  feet  per  minute  to  200  feet  per  minute,  so  that 


transmit  the  load  with  a  fairly  constant  slippage,  and 
therefore  relatively  uniform  speed.  Following  every 
change  in  load  transmitted,  there  is,  of  course,  a  slight 
change  in  the  amount  of  belt  slippage  on  the  pulleys, 
which  necessarily  effects  to  a  certain  extent  the  "draw" 
of  the  sheet  between  the  sections,  caused  by  the  differ- 
ence in  relative  speeds  between  the  sections  which  have 
taken  place.  It  is  well  known  that  variations  in  belt 
slippage  are  also  caused  by  changes  in  the  humidity  of 
the  atmosphere,  effecting  both  the  tension  of  the  belt 
and  the  co-efficient  of  friction  between  the  two  sur- 
faces, or  by  water,  oil  or  foreign  matter  of  any  kind 
reaching  the  surface  of  the  belt  or  pulleys.  On  account 
of  the  liberal  rating  of  the  belts  which  are  commonly 
used,  the  degree  of^  variation  of  belt  slippage  has  not 
been  sufficient  to  interfere  seriously  with  operations,  al- 
though it  does  frequently  cause  breakages  of  the  paper 
sheet  as  it  passes  from  one  section  of  the  machine  to 


"IG.   2 — CONTROL  BOARD   FOR   SECTIONAL  DRIVE    l66   INCH    FOURDINIER   BOOK    I'AI'ER    MACHINE 


whatever  method  of  drive  is  used,  it  must  be  capable  of 
operating  over  a  considerable  range  of  speeds.  Four- 
drinier  paper  machines  seldom  operate  at  speeds  lower 
than  50  or  100  feet  per  minute.  The  upper  limit  of  speed 
so  far  obtained  is  1000  feet  per  minute.  Many  ma- 
chines ,  however,  are  operating  continuously  at  from 
600  to  700  feet  per  minute. 

The  most  common  method  of  driving  paper  ma- 
chines has  been  by  means  of  a  variable  speed  engine, 
or  an  adjustable-speed  direct-current  motor.  Each  of 
the  several  sections  is  driven  from  a  common  line  shaft 
by  reduction  gears,  belts  and  pulleys  or  some  type  of 
rope  drive,  the  belts  being  made  to  operate  with  pulleys 
slightly  tapered  or  conical  in  form,  so  that  by  shifting 
the  belt  toward  one  end  of  the  pulley  or  the  other,  the 
required  adjustment  of  speed  for  each  individual  sec- 
tion can  be  obtained. 

Since  the  variations  in  load  on  any  individual  sec- 
tion at  a  given  speed  are  not  great,  seldom  exceeding 
20  or  25  percent,  the  belt  can  be  depended  upon  to 


another,  and  more  often  causes  undue  straining  of  the 
sheet  so  that,  while  it  does  not  actually  break  on  the 
paper  machine,  it  may  break  later  while  passing  through 
printing  presses. 

Heretofore,  mechanical  drive  has  been  used  almost 
exclusively  for  the  various  sections  of  the  paper  ma- 
chine. The  reason  motors  have  not  been  used  for  driv- 
ing the  individual  sections,  was  because  no  means  had 
been  found  whereby  their  speeds  could  be  controlled 
accurately  enough  to  prevent  breaking  of  the  paper, 
most  of  the  trials  of  sectional  motor  drive  having  re- 
sulted disastrously.  From  the  fact  that  the  relative 
speeds  of  the  sections  have  to  be  adjusted  from  time  to 
time,  synchronous  motors  are  out  of  the  question,  and 
induction  motors,  on  account  of  their  inherent  regula- 
tion characteristics,  are  equally  unsuitable.  Direct- 
current  motors,  on  the  other  hand,  can  be  designed  to 
operate  over  wide  ranges  of  speed,  and  offer  great  flexi- 
bility of  control,  and  the  only  thing  that  has  interfered 
with  their  general  adoption  has  been  the  absence  of  a 


THE  ELECTRIC  JOURNAL 


Vol.  X\'III,  No.  3 


suitable  type  of  speed  regulator.  Recent  investigations 
have  shown  that,  to  prevent  breakage  or  undue  strain- 
ing of  the  paper  as  it  passes  from  one  section  to  an- 
other, the  variation  of  speeds  between  sections  must  be 
maintained,  a>  an  average  value,  within  one-tenth  of 
one  percent.  It  is  also  necessary  to  raise  or  lower  the 
speed  of  the  entire  paper  machine  by  small  amounts 
from  time  to  time,  without  interfering  in  any  way  with 
the  draw,  or  relative  speeds  of  the  various  sections,  and 
it  is  necessary,  when  changing  from  one  grade  of 
paper  to  another,  to  operate  at  widely  different  speeds; 
speed  variations  of'V  to  i  or  even  lo  to  i  frequently 
being  encountered.  Obviously,  no  standard  regulating 
equipment  heretofore  on  the  market  would  meet  these 
exacting  requirements. 

For  many  years,  manufacturers  and  engineers  have 
appreciated  the  great  loss  of  power  occasioned  by  the 
existing  mechanical  type  of  paper  machine  drives,  the 
enormous  amount  of  space  required  for  the  accom- 
modation of  the  lontr  line  shafts,  pulleys,  belt  drives. 


veloped.  This  new  system  of  sectional  paper  machine 
drive  involves  the  development  of  a  type  of  regulator 
not  heretofore  used,  whereby  the  speed  of  the  direct- 
current  driving  motors  is  maintained  automatically 
within  one-tenth  of  one  percent;  and  the  use  of  other 
standard  control  equipment  for  starting  and  stopping 
the  motors.  The  regulator  equipment  itself  does  not  in- 
clude any  delicate  instruments  or  apparatus  likely  to 
get  out  of  order,  such  as  are  usually  associated  with 
exceptionally  sensitive  regulating  devices,  but  is  fully 
as  rugged  and  reliable  in  every  respect  as  the  most  ap- 
proved control  apparatus  used  in  industrial  applications. 
The  complete  system  of  sectional  paper  machine 
drive  and  control  herein  described  consists  of  an  adjust- 
able voltage,  direct-current  generator,  of  sufficient  ca- 
pacity to  drive  the  entire  paper  machine,  with  direct- 
connected  exciter;  a  direct-current  adjustable-speed 
motor  for  each  section  of  the  machine;  suitable  means 
for  connecting  the  motor  to  each  section  of  the  paper 
machine   driving   shaft;    and   a   control    system   which 


IK..    J-  -ol'l-.Ki.    ._H.\.N(-.KK    AND    KREQUENCi'    GENER.\TOK 

reduction  gear  units,  friction  clutches,  etc.,  and  the 
personal  and  fire  hazard  unavoidably  associated  with 
this  type  of  transmission.  Still  more  serious  is  the 
great  loss  of  production  resulting  from  the  frequent 
paper  breakages  caused  by  excessive  belt  slippage  and 
interruptions  of  operation  for  repairs  to  the  various 
parts  of  the  mechanical  system,  such  as  the  friction 
clutches,  belts  and  gear  units. 

These  disadvantages  can  all  be  eliminated  by  the 
substitution  of  sectional  individual  motor  drive,  with 
a  sufficiently  sensitive  scheme  of  controlling  the 
motors,  which  would  at  the  same  time  be  suffi- 
ciently rugged  to  withstand  severe  and  continuous  op- 
eration in  the  hands  of  unskilled  labor,  and  would  be 
free  from  the  necessity  of  adjustment  or  care  by  skilled 
electricians. 

In  response  to  the  increasing  demand  for  sectional 
motor  drive,  greatly  accentuated  by  the  desire  to  in- 
crease paper  machine  speeds,  which  are  limited  by  the 
mechanical  system  of  drive  rather  than  the  characteris- 
tics of  the  machine  itself,  a  perfected  type  of  sectional 
individual  motor  drive  for  paper  machines  with  auto- 
matic   regulation    and    control    has    recently    been    de- 


ne.  4— MASTER   FREQUENCY   GENER.VTOR  SET 

automatically  maintains  the  correct  speed  of  each  in- 
dividual motor;  together  with  push  button  stations  for 
starting,  stopping  and  adjusting  the  speed  of  the  paper 
machine  as  a  whole. 

The  generator  usually  forms  part  of  a  standard 
synchronous  motor-generator  set  or  turbine-generator 
unit,  and  is  a  250  volt,  adjustable-voltage,  separately- 
excited  machine  with  a  constant  voltage  250  volt  ex- 
citer of  sufficient  capacity  to  furnish  excitation  for  the 
synchronous  motor  field,  the  generator  and  motor  fields, 
and  for  the  control  circuit  of  the  regulator.  The 
motors,  are  250  volt,  separately-excited  machines,  and 
may  be  of  any  desired  speed,  dependent  upon  the  par- 
ticular requirements  of  the  paper  machine  involved. 
Where  a  comparatively  small  range  of  speed  for  the 
paper  machine  is  desired,  that  is,  not  more  than  3:1  or 
4:1,  this  is  accomplished  by  voltage  control  of  the  gen- 
erator through  a  motor-operated  field  rheostat.  Where 
very  wide  ranges  of  speed,  such  as  10:1  are  required, 
both  generator  voltage  control  and  motor  field  control 
are  used,  the  same  motor-operated  face  plate  controller 
or  rheostat  serving  to  insert  resistance  in  the  shunt 
fields  of  the  several  motors  uniformly,  after  the  gener- 
ator has  been  brought  to  full  voltage. 


March,   1921 


THE   ELECTRIC  JOURNAL 


81 


The  automatic  control  system  consists  of  a  small 
master  frequency  generator  driven  by  a  small  direct- 
current  motor  operating  in  parallel  with  the  section 
driving  motors  and  separately  excited ;  a  small  fre- 
quency generator  driven  from  each  of  the  section  driv- 
ing motors  through  a  small  speed  changer  consisting 
of  two  cone  pulleys,  to  one  of  which  the  frequency 
generator  is  coupled ;  a  powerful  synchronous  type  of 
rotary  relay  for  each  driving  motor,  which  serves  to 
make  an  electrical  contact  in  one  direction  or  the  other 
on  the  slightest  unbalance  of  frequencies;  and  a 
motor-operated  field  rheostat,  under  control  of  the 
relay,  in  the  shunt  field  circuit  of  each  driving  motor. 
The  master  frequency  generator  is  common  to  all  sec- 
tions of  the  paper  machine,  whereas  each  section  has 

Couch     1st  Press       2nd  Press         3rd  Press  Dryers 


their  own  ball  bearings,  which  is  practically  negligible. 
By  shifting  the  small  belt  on  these  speed  changers  by 
means  of  a  hand  wheel,  the  relative  speeds  of  the  sec- 
tions, or  the  draw  of  the  paper,  as  it  is  called,  is  accur- 
ately and  positively  detennined  by  the  operator,  and  is 
thereafter  maintained  automatically  at  the  correct 
value.  Any  unbalancing  of  the  two  frequencies  at  the 
rotary  relay,  caused  by  change  in  speed  of  the  driving 
motor,  immediately  causes  a  positive  synchronous 
movement  of  the  relay,  making  an  immediate  contact 
and  thereby  adjusting  the  field  strength  of  the  motor, 
and  returning  the  speed  to  the  required  value. 

Before  any  governor  or  regulator  can  function, 
there  must  be  a  change  of  some  kind,  in  either  load  or 
s;)eed.  as  otherwise  there  would  be  no  occasion  for  the 

Dry<^rs  Calender     Rr,l 


rywx^'^y.T^'^y.'^yT.'^TyTy,"^,^,  ^  ,^,  <^x 


iFkMblcCotiplme 
J  Reduction  Gear  unit 
f  Control  Spe«d  Changer 
DSection  Frequency  Generator 


FIG.    5 — SCIIEMATir    PI. 


AM)    WIKIXG    DIAliRAM    OF    WESTINC.IinUSE    SYSTEM    OF    SECTIONAL    INDIVIUI'AI.    MOTOR    DRIVE 


its  own  section  frequency  generator,  relay,  and  motor- 
operated  field  rheostat,  together  with  an  effective  anti- 
hunting  device. 

The  small  frequency  generators  are  all  excited  by 
alternating  current,  but  since  the  master  and  section 
frequency  generators  are  excited  from  the  same 
source,  any  variations  in  frequency  or  voltage  of  the 
exciting  source  have  no  effect  upon  the  regulation,  as 
they  do  not  disturb  the  balance  of  frequencies  at  the 
rotary  relay.  Since  no  appreciable  amount  of  power 
is  required  to  operate  the  rotary  relay,  these  frequency 
generators  are  small  in  size.  The  small  speed  changers 
referred  to  are  of  small  size,  as  they  do  not  have  to 
transmit  power,  but  simply  overcome  bearing  friction 
of  the  small   frequency  generator  and  the   friction  of 


regulator  to  correct  anything.  However,  these  changes 
in  speed  need  not  Jje  large  enough ^to  be  perceptible  to 
the  eye  or  detectable  by  ordinary  indicating  apparatus, 
to  actuate  this  new  regulator.  In  fact,  the  regulator 
will  detect  changes  in  speed  of  a  few  thousandths  of 
one  percent,  and  make  the  necessary  correction  imme- 
diately, and  without  any  tendency  to  overtravel  or  hunt, 
so  that  no  perceptible  change  will  be  found  in  the  draw 
of  any  section. 

A  control  board  is  provided  in  connection  with  each 
paper  machine,  having  a  master  control  panel  for  the 
paper  machine  as  a  whole,  controlling  the  generator  and 
master  frequency  generator:  and  a  unit  section  control 
panel  for  each  of  the  section  driving  motors.  Starting 
equipment  is  provided  on  each  of  these  panels,  consist- 


82 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


ing  of  motor-operated  cam  accelerating  switches  with 
line  contactors  under  the  control  of  suitable  push  button 
stations  for  starting  and  stopping  the  individual  motors, 
and  the  entire  paper  machine  as  a  whole.  The  master 
rheostat,  under  push  button  control,  provides  means  for 
adjusting  the  speed  of  the  paper  machine  as  a  unit,  over 
the  entire  range  of  speed.  The  rotary  contactor  relay 
and  motor-operated  field  rheostat  for  each  section  is 
also  located  on  the  unit  section  control  panel.  The  push 
button  stations,  arranged  conveniently  on  or  near  the 
apparatus,  provide  means  for  starting,  stopping  and  ob- 
taining any  desired  speed  of  the  paper  machine  in  the 


shortest  time  and  in  the  most  efficient  possible  manner. 
In  this  way  and  in  the  elimination  of  the  cumbersome 
mechanical  drive,  a  great  deal  has  been  accomplished 
in  increasing  production  and  improving  overall  effi- 
ciency and  economy  from  every  standpoint. 

While  the  paper  machine  has  been  one  of  the  last 
places  in  paper  manufacture  to  derive  the  benefits  of 
complete  electrification,  greater  benefits  will  doubtless 
accrue  from  this  advanced  step  in  motor  and  control 
application  than  from  any  other  phase  of  electrification 
in  the  paper  industry. 


Mou  latin 

111  .i,:-;l!^^.:     , 


h/en 


I  M  .}r  Cornice  Works,  ,San  Francisco 


ELBERT   KRAMER 

Industrial  Heating  Dept., 
Westinghouse  Electric  &  Mfg.   Company 


THE  CLEANLINESS  of  electricity  as  a  fuel  is 
a  recognized  virtue.  An  even  greater  advantage 
of  electricity  over  fuels  in  general,  is  the  relia- 
bility of  service  and  its  unvarying  heat  at  definite  ad- 
justments; together  with  the  simple  means  of  control- 
ling the  temperature,  as  well  as  the  duration  of  the 
cycle. 

The  Forderer  Cornice  Works  of  San  Francisco, 
manufacturers  of  hollow  steel  doors,  interior  trims, 
steel  partitions,  hollow  steel  window  frames  and  sashes, 
have  recently  installed  a  kiln-type  eti,-iniclin<:r  nven    huilt 


of  three-eighths  inch  steel  plate,  resting  un  two  inches  ' 
of  heat  insulation  in  brick  form.     There  is  no  through 
metal  between  the  inner  and  outer  surfaces  of  the  walls, 
top  or  doors,  except  at  the  junction  of  the  inner  and 
outer  walls  at  either  end  of  the  oven. 

The  electrical  equipment  is  arranged  to  give  in- 
dividual operation  to  either  or  both  ends  of  the  oven 
with  the  heat  insulated  barrier  in  place ;  or,  operation  in 
unison,  of  both  ends,  with  the  heat  insulated  barrier 
removed.  Each  end  of  the  oven  is  controlled  by  its 
cwn  bank  of  heaters,  control  panel,  electric  control 
thermostat    system   of   ventilation    (motor   driven    ex- 


riG.    I — INTERIOR  OF  OVEX,   SHOWING   HE.\TERS    MOUNTED 
ON   SIDE   WALLS 

One  section  of  the  protecting  screen  is  removed.  The  bus 
bars  are  mounted  directly  over  the  heaters.  The  oven  is  loaded 
with  sections  of.  metal  furniture,  ready  for  baking. 

along  the  most  modern  engineering  lines.  The  interior 
dimensions  of  the  oven  are  8  ft.  high,  lO  ft  wide  and 
22  ft.  long.  Provision  is  made  for  the  insertion  of  a 
heat-insulated  barrier  spanning  the  center  of  the  oven, 
thermally  isolating  each  end.  The  walls,  doors  and  top 
are  of  the  double  wall  construction,  being  filled  with 
three  inches  of  powdered  heat  insulation.     The  floor  is 


-KILN-TYPE  ENAMELING  OVEN   RECENTLY   INSTALLED   IN 
FORDERER  CORNICE    WORKS   OF   SAN   FRANCISCO 

hauster,  special  inlet  and  exhaust  system),  door  switch 
and  push  button  station.  A  time  clock  is  connected  for 
time  or  cycle  control  of  either  or  both  ends  of  the  oven 
independently,  or  both  ends  in  unison. 

The  heaters  are  of  the  open  ribbon  construction, 
wound  on  fire  clay  bushings,  assembled  on  steel  tie  rods, 
the  whole  supported  by  pressed  steel  end  plates.  The 
construction  of  these  heaters  permits  of  their  being  sus- 
pended from  flanges  on  the  heater  end  frame,  allowing 
ready   expansion   and   contraction   of   all   parts   of   the 


March,   1921 


THE   ELECTRIC  JOURNAL 


heater  as  well  as  affording  a  suiiple  means  of  mounting. 
Each  heater  has  a  capacity  of  2.3  kilowatts,  there  being 
32  heaters  installed,  having  a  combined  capacity  of  73.6 
kilowatts.  The  power  for  the  heaters  is  controlled  by  a 
three-pole  magnet  switch  or  contactor. 

The  ventilating  system  is  so  designed  that  the  ends, 
the  corners,  and  the  center  of  the  oven,  all  receive  the 
same  degree  of  ventilation.  Cold  air  enters  through  the 
top  of  the  oven,  the  exhaust  air  being  taken  three- 
fourths  from  the  bottom  and  one-fourth  from  the  top. 
The  motor  for  the  exhauster  is  controlled  by  two  single- 
pole  relays.  The  control  circuit  for  the  automatic  panel 
is  connected  on  the  motor  side  of  the  two  relays  men- 
tioned above,  in  such  a  way  that  the  motor  driven  ex- 
hauster is  always  operating  when  the  control  circuit  is 
energized.  A  thermostat  push  button  station  and  door 
switch  are  so  connected  in  the  control  circuit,  that  the 
following  cycle  of  operation  can  be  obtained  :- 


FU7.    3 — CONTROL    I'.VNKI. 

Consisting  of  two  IJ5  ampere,  lliroc-pole  contactors,  witli 
relays  for  automatic  temperature  control.  Two  thermostats, 
one  for  each  half  of  oven,  are  mounted  to  the  upper  right  and 
left  of  the  panel.  Motor  driven  e.xhaustors  and  ventilation 
ducts  arc  also   shown. 

With  the  oven  cold,  at  the  start,  the  thermostat 
will  make  contact  on  the  low  position.  The  door  switch 
and  push  button  are  closed,  the  control  being  completed 
through  the  low  contact  of  the  thermostat,  energizing 
the  control  relay,  which  in  turn  closes  the  three-pole 
magnet  switch,  or  main  contactor  furnishing  power  to 
the  heaters.  As  the  oven  ternperature  rises,  the  thermo- 
stat will  leave  its  low  position,  the  three-pole  magnet 
switch,  controlling  the  oven  heaters  being  held  in 
through  a  mechanical  interlock  on  the  control  relay. 
The  thermostat,  on  reaching  the  high  position,  short- 
circuits  the  control  relay,  de-energizing  the  three-pole 
magnet  switch,  thereby  cutting  oft"  the  power  from  the 
oven  heaters.  The  oven,  on  again  reaching  its  low  or 
minimum  temperature,  repeats  the  above  cycle. 

It  was  found  necessary  and  beneficial  to  have  the 
duration  of  the  bake  under  automatic  time  control. 
The  control  circuits  of  both  ovens  have  been  so  con- 


nected with  reference  to  this  time  switch,  that  the  op- 
erator may  put  under  time  control  either  one  or  both 
ends  of  the  oven  simultaneously  with  insulated  heat 
barrier  in  position;  or  both  ends  operated  in  unison 
with  heat  barrier  removed.  This  scheme  of  operation 
permits  the  workmen  to  fill  the  ovens  ready  for  a  bake 
before  closing  the  shop,  the  time  clock  starting  and 
stopping  the  bake  during  the  night  or  early  morning, 
the  material  being  thoroughly  baked  and  ready  to  be 
taken  from  the  oven  when  the  workmen  arrive  the  next 
morning.  Putting  through  a  bake  between  closing  time 
of  one  day  and  opening  time  the  next  morning  is  a 
100  percent  saving  of  labor  during  the  cycle  of  that  par- 
ticular bake.  Another  labor  saver  is  the  electric  con- 
trol thermostat  or,  in  this  particular  case,  thermostats 
\vhich  keep  the  temperature  of  the  ovens  at  a  predeter- 
mined value. 

Determining  the  proper  baking  temperature  and 
duration  of  bake  for  every  color  and  type  of  enamel 
used  in  their  process  has  enabled  the  Forderer  Cornice 
Works,  with  the  aid  of  perfect  temperature  and  time 


■^ i-*-^ \-flN»-T[kjMUl-i-^ 


Frc.  4 — <;r.\phic  metkr  recorps  of  volt.\gk  .\xd  curre.vt 
The   fluctuations   in  voltage  between   II   and   12  were  pro- 
duced by  the  operation  of  a  motor  driven  shear  and  are  not 
characteristic  of  the  heater  load. 


control,     to    turn     out     uniformly     finished    material. 
"Spoilage"  is  an  unknown  term  to  this  concern. 

That  the  characteristics  of  this  installation  may  be 
fully  understood,  the  following  operating  conditions  are 
given : — • 

Automatic  time,  temperature  and  ventilation  control. 

Power  Service,  220  volt,  two-phase,  60  cycle. 

Connected  capacity  73.6  kw. 

Initial  temperature  50  degrees   F. 

Final  temperature  200  degrees  F. 

A  bake  of  4000  pounds  consisting  chiefly  of  hollow 

steel  doors,  was  placed  in  the  oven,  with  heat  insulating 

barrier  removed.     The  results  of  this  particular  bake 

were  as  follows: — 

Load,  4000  pounds,  hollow  steel  doors. 

Room  temperature  47  degrees  F. 

Temperature  of  ovens  at  end  of  bake  200  degrees  F. 

Time  required  to  reach  ma.ximum  temperature,  35  minutes 

Time  oven  was  lield  at  constant  temperature  (200  degrees 

F.),  3  hours. 
Kv-a  =  (V  X  I  -H  1000)  =  70.2  kw. 
Actual  kw.  (Watt-hour  Meter)  =  69.S2  kw. 

69.82 
Power- factor  of  heaters    -— — —  =  98.5  percent. 

Power  consumed     for  entire  bake  =  100  kw-hr.  for 
4000  pounds  metal  baked. 

100 
Power  consumption  per  pound  of  metal  baked  =— — 

0.025  kw-hr. 
Pounds  of  metal  per  kw-hr.  =  40. 


Renewal  of  iho  c'acoiiary  Coostractloi]  jji 


iLo 


L.  C.  VVINSHIP 

Electrical  Superintendent 
Boston  &  Maine  Railroad. 


NINE  years  of  exposure  to  gas,  moisture  and  cor- 
rosive solutions  from  the  tunnel  roof  have  been 
sufficient  to  take  the  life  of  the  copper  messen- 
ger, which  was  installed  in  the  Hoosac  Tunnel  at  the 
time  of  the  electrification  in  191 1.  This  messenger, 
practically  severed  in  many  places  and  materially 
weakened  throughout  its  entire  length,  has  now  given 
place  to  another,  similar  in  nature,  but  protected  in  such 
a  way  as  to  give  promise  of  a  much  longer  life. 

Electrical  conductivity  and  resistance  to  corrosion 
were  two  features  which  received  particular  considera- 
tion in  the  determination  of  a  type  of  construction 
which  would  be  suitable  for  this  location.  Auxiliary 
feeders  were  not  to  be  provided  and  the  corrosive  action 
of  the  smoke  and  moisture,  which  would  be  present  to 
some  extent,  must  be  guarded  against.  The  type  of 
construction  which  was  finally  developed  consisted  of 
suspended  brackets  carrying  double  insulation  and  a 
conducting  system  made  up  of  a  hard  drawn  copper 
messenger  of  seventeen  strands  and  300000  circular 
mil  cross  section,  from  which  were  suspended  two  4-0 
grooved  Phono-electric  trolley  wires.  The  trolley 
hangers,  insulator  pins,  studs  and  messenger  clamps 
were  of  bronze,  the  brackets  were  covered  with  tape 
and  painted,  and  the  remaining  fittings,  which  were  of 
iron,  were  galvanized  and  painted. 

The  tunnel  operation  provides  for  the  handling  of 
the  steam  locomotive  with  the  train,  and  although  this 
locomotive  is  ordinarily  not  working,  a  small  amount  of 
moisture  and  gas  is  given  off,  which  tends  to  collect  on 
and  around  the  overhead  construction. 

During  the  warmer  months,  the  ventilating  fan  at 
the  central  shaft  draws  in  the  warm  air  through  the 
tunnel  portals  and,  as  the  temperature  of  this  air  drops 
in  its  passage  to  the  shaft,  the  moisture  condenses  on 
the  catenary  structure.  This  moisture  tends  to  fix  a 
certain  amount  of  dust  from  the  air,  together  with  the 
sulphur  gas  which  comes  from  the  locomotives,  to  such 
an  extent  that  a  material  deposit,  highly  acid  in  nature, 
is  built  up  on  the  conductors.  This  deposit  effects  a 
very  general  and  extensive  deterioration  which,  while 
more  rapid  during  the  summer,  continues  to  some  ex- 
tent throughout  the  entire  year. 

Much  more  serious  than  this  action,  however,  was 
one  which  has  occurred  at  a  number  of  definite  points 
in  the  tunnel,  and  which  has  been  manifested  by  the 
gradual  disintegration  of  the  messenger  over  a  length 
varying  from  four  to  six  inches.  The  individual 
strands  in  this  short  length  would  successively  part 
under  strain  as  their  section  became  inadequate  and.  in 


several  instances,  the  action  progressed  undiscovered' 
until  the  messenger  had  been  completely  severed.  This 
type  of  failure  was  first  noticed  in  1913,  and  the 
peculiar  action  leading  towards  it  has  been  a  source  of 
concern  ever  since.  In  the  attempt  to  guard  against 
complete  failure  of  the  messenger,  close  inspections 
have  been  made  and  re-enforcements  to  the  number  of 
about  one  hundred  have  been  applied  at  the  points 
where  this  local  deterioration  has  been  in  evidence. 
Subsequent  inspections  have  shown  similar  deteriora- 
tion of  the  re-enforcing  member  at  the  same  point  as  on 
the  messenger  and,  in  at  least  one  instance,  this  has  been 
manifest  in  the  second  re-enforcement. 

While  the  cause  of  this  peculiar  condition  has  not 
been  determined,  it  appears  that  the  water  from  the  tun- 
nel roof  is  one  factor.  Whether  or  not  this  moisture 
tends  to  fix  more  effectively  the  corrosive  agent  in  the 
atmosphere,  or  comes  as  an  active  solution  from  the 
rock  of  Ihe  tunnel  roof,  is  still  a  subject  for  investiga- 
tion. 

This  gradual  and  intensive  deterioration  of  the 
messenger  had  progressed  to  such  a  point  in  the  fall  of 
1919  as  to  make  evident  the  necessity  of  a  complete 
replacement  inside  of  the  next  twelve  months,  and  steps 
were  taken  looking  towards  a  possible  improvement 
upon  the  original  installation.  As  equivalent  conduc- 
tivity must  be  maintained,  the  choice  of  material  was 
limited  to  copper,  and  the  problem  then  seemed  to  be 
one  of  adequately  protecting  this  copper  from  the  cor- 
rosive agents.  Such  protection  appeared  to  be  possible 
through  the  use  of  special  paints  or  similar  preparations 
and  a  number  of  these  preparations  were  given  a  test  in 
the  tunnel  during  a  part  of  1920.  One  of  these,  a  vis- 
cous and  non-hardening  compound,  appeared  to  have 
the  qualities  which  would  make  it  suitable. 

With  this  idea  of  protection  particularly  in  mind, 
the  specifications  of  the  new  messenger  were  so  drawn 
as  to  provide  for  the  tinning  of  the  strands  and  the 
covering  of  the  messenger  with  one  serving  of  braid, 
this  braid  to  be  impregnated  with  a  weather  proofing 
compound.  In  addition  a  heavy  coat  of  the  protective 
compound  was  to  be  applied  after  the  installation. 

The  necessity  of  the  renewal  of  the  trolley  hangers 
and  the  trolley  was  not  as  pressing  as  that  of  the  mes- 
senger, as  the  hangers  for  the  most  part  were  in  ser- 
viceable condition  and  the  wear  of  the  trolley  wire,  ex- 
cept at  a  few  points,  had  reached  only  about  one-half 
of  that  allowable.  The  corrosion  on  the  top  of  the 
trollev  wire  had  progressed,  however,  to  such  an  extent 
as  to  produce  a  loosening  of  the  clips  in  a  number  of 


March,   1 921 


THE   ELECTRIC  JOURNAL 


85 


instances,  and  a  renewal  in  about  two  years  was  indi- 
cated. 

While  it  would  have  been  possible  with  the  replace- 
ment of  the  hanger  clips  to  have  installed  a  new  mes- 
senger vi^ith  the  old  hangers  and  trolley  wire,  the  labor 
charge  and  the  cost  of  the  delay  which  would  result 
from  the  withdrawal  of  one  track  from  service,  a  large 


FIG.    r — SECTIONS    OF    THE    TUNNEL    MESSENGER    WITH    TWO 
REIN'FORCEMENTS 

part  of  which  would  have  again  been  incurred  within  a 
comparatively  short  time  with  the  renewal  of  the  trolley 
wire,  made  it  advisable  to  sacrifice  such  service  as  re- 
mained in  the  hangers  and  the  trolley  wire  and  make  a 
complete  replacement.  Also,  as  a  part  of  this  replace- 
ment, to  protect  the  messenger  wire  in  such  a  way  as 
to  make  its  life  equal  to  that  of  the  hangers  and  the 
trolley  wMre.  Consequently  new  hangers  and  trolley 
wire  like  those  of  the  original  installation  were  pro- 
vided. 

Inasmuch  as  electrical  operation  through  the 
tunnel  had  to  be  maintained  at  all  tinies,  it  was  neces- 
sary that  the  work  be  laid  out  and  carried  forward  in 
such  a  way  as  to  provide  not  only  for  this  continuity 
of  service,  but  for  the  safety  of  the  men  of  the  con- 
struction force.  The  arrangement  provided  for  the 
release  of  one  track  for  eight  hours  ]ier  day,  the  le- 
moval  of  power  from  the  wire  over  this  track  and  the 
adequate  grounding  of  these  wires  at  each  portal  of  the 
Tunnel.  Additional  grounds  were  provided  on  the  con- 
struction train  which  could  be  attached  to  both  the  in- 
sulator brackets  and  the  trolley  wires,  these  connec- 
tions being  required  to  take  care  of  the  voltage  which 
might  be  present  on  a  bracket  due  to  a  defective  insu- 
lator over  the  adjacent  track,  as  well  as  the  voltage  pro- 
duced on  the  trolley  wires  by  induction.  These  ground 
connections  also  afforded  protection  in  case  the  wire 
was  accidentally  energized  by  the  bridging  over  of  a 
section  break  by  an  electric  locomotive.  These  safe- 
guards, together  with  close  supervision,  made  possible 
the  completion  of  the  work  without  injury  to  any  one 
of  the  force. 

The  construction  train  was  made  up  of  one  gondola 
car,  two  box  cars,  and  from  four  to  seven  flat  cars 
equipped  with  staging.     The  gondola  car  was  used  for 


the  reels  of  wire,  one  uf  the  box  cars  for  tools,  and  the 
other  for  scrap  material.  The  necessary  illumination 
was  provided  by  acetylene  lights.  This  train  was 
handled  by  a  steam  locomotive  and  in  order  that  the 
amount  of  smoke  might  be  as  small  as  possible,  a  very 
heavy  fire  was  built  up  immediately  prior  to  entering 
the  tunnel,  which  made  possible  such  movements  as 
were  necessary  during  an  interval  of  two  or  three  hours 
without  additional  firing.  Varying  tunnel  draft  condi- 
tions were  also  taken  advantage  of  and  as  a  result  of 
these  precautions,  it  was  possible  to  carry  forward  the 
work  without  the  aid  of  special  ventilating  apparatus 
on  the  construction  train  and  without  serious  interfer- 
ence by  smoke. 

The  messenger  cable  was  first  run  out  and  pulled 
so  that  the  sag  between  the  suspension  points  was 
slightly  less  than  that  of  the  old  messenger  wire,  tem- 
porary fastenings  were  made  at  each  insulator  and  the 
two  messengers  temporarily  tied  together  at  interme- 
diate points.  The  trolley  wires  were  next  run  out,  the 
movement  of  the  train  being  so  regulated  as  to  supply 
this  trolley  in  about  two  hundred  foot  sections.  These 
were  also  pulled  in  such  a  way  as  to  make  the  height 
above  the  rail  at  the  center  of  the  span  about  two  inches 
greater  than  that  at  the  insulator,  allowance  thus  being 
made  for  a  certain  amount  of  elongation  in  both  the 
messenger  and  trolley  wires.  The  old  messenger  was 
then  removed  from  the  insulator  clamps  and  the  new 
put  into  place  and  fastened.  The  new  hangers  were 
applied  and  clipped  in  and  the  section  of  the  old  con- 
struction cut  free  and  dropped  to  the  top  of  the  staging 
where  it  was  further  cut,  at  the  hangers,  into  lengths 
of  about  ten  feet,  both  for  convenient  handling  as  well 
as  the  easy  separation  of  the  hangers  from  the  rest  of 
the  material  as  these  appeared  to  be  worth  reclaiming. 
The  presence  of  the  live  Irolley  wire  over  the  adjacent 


FIG.    2 — SECTIO.XS 


OK   THE   TUNNEL   MESSENGER   WITH    SINGLE 
REINFORCEMENT 


track  called  for  extreme  care  in  the  removal  of  this  ma- 
terial and  consequently  no  attempt  was  made  to  handle 
the  old  wire  otherwise  than  in  short  sections. 

At  the  close  of  the  day's  work,  the  trolley  wires 
were  dead-ended  and  so  fastened  to  the  old  trolley 
wires  at  the  point  where  the  clipping  in  was  discon- 
tinued as  to  make  possible  the  easy  movement  of  the 


86 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


trolley  shoe  from  the  old  to  the  new  construction.  This 
connection  was  made  in  such  a  way  that  no  difficulty 
was  experienced  in  restoring  the  line  to  service  imme- 
diately upon  the  withdrawal  of  the  work  train. 

To  preserve  the  continuity  of  the  braid. on  the  mes- 
senger as  far  as  possible,  contact  at  each  hanger  was 
provided  by  simply  removing  from  the  lower  side  of 


FIG.    3 — BRONZE    TROLLEY    H.'iNGER 

Showing  the  progress  of  corrosion. 

the  messenger  a  section  of  the  braid  of  the  same  size  as 
the  contact  plate  on  the  top  of  the  hanger  rod.  Great 
care  was  taken  to  make  a  nice  fit  at  this  point,  and  in 
case  the  braid  was  torn  in  applying  the  hanger,  tape 
was  applied  to  cover  the  exposed  part  of  the  messenger. 
All  other  exposed  portions  of  the  messenger  were  simi- 
larly covered  with  tape. 

The  corrosion  of  the  top  of  the  trolley  wire,  indi- 
cating that  the  reduction  in  metal  at  the  top  rather  than 
at  the  bottom,  would  determine  the  length  of  service, 
suggested  the  protection  of  the  top  of  the  new  trolley 
wire  with  a  coating  of  the  same  preparation  as  that  ap- 
plied to  the  messenger,  and  it  subsequently  appeared  ad- 
visable to  extend  this  treatment  to  the  hangers,  brackets 
and  other  details  of  the  construction.  The  behavior  of 
this  protective  coating  will  be  watched  veiy  carefully  to 
determine  whether  or  not  periodic  applications  to  mes- 
senger, hangers  and  trollej'  wire  may  not  make  further 
renewals  unnecessary  until  such  time  as  the  trolley  wire 
is  worn  to  the  safe  limit. 

INCREASING  TROLLEY  CLEARANCE 

During  the  past  few  years  the  clearance  between 
the  top  of  the  rail  and  the  trolley  wire  has  been  main- 
tained at  fifteen  feet,  six  inches  and  a  published  clear- . 
ance  of  fourteen  feet,  eight  inches  has  controlled  the 
height  of  equipment  through  the  tunnel  with  especial 
reference  to  brake  staffs.  As  a  large  number  of  the 
cars  from  foreign  roads  moving  towards  New  England 
are  fitted  with  brake  staffs  slightly  in  excess  of  four- 


teen feet  eight  inches,  it  has  been  necessary  either  to 
shorten  these  staffs  or  reroute  the  cars  around  the 
tunnel.  As  a  very  large  percent  of  these  high  brake 
staflfs  were  fifteen  feet  and  less  above  the  rail,  it  ap- 
peared that  an  increase  of  clearance  of  only  four  inches 
would  result  in  a  considerable  saving  in  the  cost  of 
cutting  otf  staffs  or  rerouting  the  equipment. 

Roof  clearances  above  the  insulators  and  messen-  . 
ger  wire  were  such  as  to  make  the  increase  possible, 
except  at  a  few  points,  and  it  appeared  that  this  addi- 
tional four  inches  could  be  obtained  by  simply  raising 
the  secondary  insulators  and  with  them  the  transverse 
brackets  which  supported  the  primary  insulators  and 
the  messenger  wire.  As  the  equipment  and  construc- 
tion force  which  were  used  in  the  wire  renewal  would 
be  available  for  this  increase  in  clearance,  it  was  evi- 
dent that  the  cost  of  this  work  would  be  comparatively 
light,  and  arrangements  were  made  to  proceed  therewith 
as  soon  as  the  new  wire  was  in  place. 

The  original  clearances  between  the  rail  and  the 
trolley  wire  were  not  absolutely  uniform,  and  to  obtain 
the  desired  four  inch  increase,  it  was  necessary  to 
raise  the  brackets  two,  four  and  six  inches,  as  the  par- 
ticular location  demanded.  The  work  was  necessarily 
carried  on  from  one  track,  and  care  had  to  be  exercised 
to  prevent  the  breakage  of  insulators  and  interference 
with  the  energized  line  over  the  other  track.  The  stud 
was  removed  from  the  secondary  insulator  pin,  a  jack 
was  then  placed  under  the  end  of  the  transverse  bracket 
and  this  end  so  raised  as  to  permit  the  insertion  of  a 
two  inch  block  between  the  insulator  pin  and  the  sup- 
porting hanger.  A  longer  stud  was  then  applied  and 
secured.  The  flexibility  of  the  structure  was  such  as 
to  make  this  rise  of  two  inches  practicable  without  en- 
dansferinsj  the  secondarv  insulator  over  the  other  track, 


FJG.    4 — CROSS    SF.CTION   OF    HOOSAC   TUNNEL.   SHOWING   CLEARAXi  I  - 

but  as  lifts  in  excess  of  this  amount  were  not  considered 
safe,  it  was  necessary  to  make  this  two  inch  lift  at  all 
points  on  one  track,  then  a  four  inch  lift  with  the  in- 
sertion of  a  four  inch  block  on  the  other  track,  and 
finally  a  second  two  inch  lift  on  the  first  track  with  the 
addition  of  a  second  two  inch  block.  At  points  where 
six  inch  blocks  were  required,  the  method  of  procedure 


March,  192 1 


THE  ELECTRIC  JOURNAL 


87 


was  similar.  The  length  of  the  train  was  such  as  to 
make  possible  the  working  on  three  brackets  at  a  time. 

At  points  in  the  tunnel  where  the  clearance  be- 
tween the  top  of  the  insulator  and  the  tunnel  roof  was 
already  a  minimum,  a  shorter  primary  insulator  was 
installed,  and  the  secondary  insulators  then  raised.  As 
the  increase  in  height  effected  by  raising  the  secondary 
insulators  was  practically  compensated  by  the  shorter 
primary  insulator,  it  was  necessary  to  shorten  the  trolley 
hangers  in  both  sections  of  the  catenary  adjacent  to  the 
insulator  in  order  to  provide  the  desired  increase  in 
clearance.  The  clearance  between  the  trolley  wire  and 
the  bracket  with  the  original  insulator  was  so  small  as 
to  make  impracticable  the  raising  of  the  trolley  wire 
through  the  shortening  of  the  hangers,  except  with  the 
installation  of  a  shorter  insulator. 

The  final  clearance  between  the  insulator  caps  and 
the  roof,  and  between  the  messenger  and  the  roof,  at 
points  in  the  spans  were,  in  many  instances  considerably 
less  than  those  thought  necessary  when  the  original  in- 
stallation was  contemplated,  the  present  minimum  being 
about  six  inches  as  compared  with  the  proposed  mini- 
mum of  twelve  inches,  but  past  experience  has  indicated 
that  these  lesser  clearances  are  sufficient. 

The  raising  of  the  trolley  wire  brought  with  it  a 


corresponding  rise  in  running  position  of  the  locomo- 
tive trolley  shoe  and  a  very  decided  decrease  in  clear- 
ance between  the  trolley  horn  and  the  tunnel  roof  was 
experienced  at  many  places.  The  close  points  were 
located  and,  where  existing  in  the  rock,  additional 
clearance  was  readily  provided  by  chipping.  In  the 
brick  work  these  close  clearances  cannot  readily  be  in- 
creased and  it  is  there  necessary  to  operate  with  a  six 
inch  minimum.  While  this  appears  to  be  somewhat 
hazardous,  no  serious  results  are  expected  as  long  as  the 
proper  alignment  and  surface  of  the  track  is  main- 
tained. 

Eleven  thousand  volt  electrification  of  the  Hoosac 
Tunnel  was  undertaken  with  no  little  concern  with  re- 
spect to  the  behavior  of  the  insulators  and  the  catenary 
material,  and  much  thought  was  given  to  the  details  of 
a  construction  which  would  meet  the  exacting  condi- 
tions. The  ease  with  which  this  construction  has  been 
maintained  has  justified  its  use.  The  renewal  and  re- 
adjustment which  was  begun  October  7th  and  continued 
until  December  7th,  1920  was  the  first  heavy  piece  of 
maintenance  work  which  has  been  carried  forward 
since  installation  in  191 1.  Protection  has  now  been 
provided  for  the  material  which,  it  is  expected,  will  re- 
sult in  even  easier  maintenance  and  much  longer  life. 


Tincioio^  aji^J 


E.  B.  SHAND 

Power  Engineering  Dept. 
Wcstinghouse   Electric  &  Mfg.   Co. 


vSyjidii'OjacOT 


THE  PRINCIPLE  of  a  synchronous  motor  is 
sometimes  referred  to  as  the  reverse  of  the  oper- 
ation of  a  synchronous  generator.  While  this  is 
quite  true,  broadly  speaking,  the  conception  of  the 
action  of  an  alternator  is  very  often  made  up  of  ideas 
of  voltage  and  reactance  relations,  whereas  the  funda- 
mental elements  for  the  production  of  torques  are  flux 
and  current.  It  seems,  therefore,  that  the  clearest  in- 
sight into  these  principles  can  be  obtained  by  means  of 
certain  conceptions  of  the  internal  action  of  the  fluxes 
and  currents  flowing  in  the  motor  under  various  condi- 
tions. 

With  the  exception  of  a  relatively  small  resistance 
drop,  the  terminal  voltage  of  any  synchronous  machine 
is  the  result  of  the  cutting  of  the  armature  conductors 
by  the  main  air-gap  flux  and  by  the  leakage  flux  set  up 
by  the  armature  current.  As  a  matter  of  fact  there  is 
no  strict  line  of  demarcation  between  the  two  fluxes 
mentioned,  and  it  is  a  difficult  matter  to  distinguish  be- 
tween them,  either  from  the  design  of  a  machine  or 
from  its  tests.  For  the  present,  the  armature  leakage 
flux  will  be  neglected  and  it  will  be  assumed  that  all  the 
fluxes,  actually  more  or  less  dispersed,  have  been  re- 


placed by  a  single  flux  crossing  the  air-gap  in  the  same 
relative  phase  position  as  the  resultant  of  the  actual 
fluxes.  This  equivalent  flux  will  be  of  a  magnitude  di- 
r^tly  proportional  to  the  terminal  voltage  and  its  phase 
position,  considered  as  a  vector,  will  be  fixed  with  re- 
spect to  that  of  the  applied  voltage,  regardless  of  the 
conditions  under  which  the  machine  operates.  By  this 
conception  the  main  principles  can  be  explained,  while 
afterwards  the  modifications  due  to  the  leakage  flux 
will  be  taken  up. 

It  is  a  fundamental  law  that  forces  are  exerted 
when  conductors  carrying  current  are  located  in  a  mag- 
netic field.  Their  direction  is  at  right  angles  to  the  di- 
rection of  the  flux  and  they  are  proportional  to  the  pro- 
duct of  the  flux  and  the  current  involved.  Thus,  the 
torque  of  a  direct-current  motor  is  produced  by  the 
armature  conductors  carrying  current  being  located  in 
the  main  field  flux  and  the  current  directions  under 
alternate  poles  are  controlled  by  the  setting  of  the 
brushes  on  the  commutator.  Except  on  this  latter  point 
the  torque  of  a  synchronous  motor  is  produced  in  es- 
sentially the  same  manner;  the  equivalent  flux,  crossing 
the   air-gap   radially,   exerts   tangential    forces   on   any 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


current-carrying  conductor  located  on  the  surface  of 
the  armature.  To  produce  its  maximum  effect  the 
current,  considered  vectorially,  must  be  located  directly 
on  the  axis  of  this  flux;  or  the  torque  produced  by  any 
current  is  proportional  to  its  component  located  on  the 
flux  axis.  The  angular  position  of  the  current  with 
respect  to  the  flux  axis  is  controlled  by  the  variation 
of  excitation. 

The  idea  of  the  revolving  field  used  in  connection 
with  the  study  of  the  principles  of  induction  motor  op- 
eration is,  of  course,  entirely  applicable  to  the  case  of 
synchronous  motors,  so  that  the  effect  of  the  currents 
in  the  armature  conductors,  rising  and  declining  in 
successive  groups  of  coils,  can  be  considered  as  that  of 
a  current  revolving  in  the  armature  at  synchronous 
speed,  and  taking  up  various  positions  with  respect  to 
the  flux  to  correspond  in  phase  position  to  the  various 
conditions  of  load  and  power-factor. 

Let  Fig.  I  (a),  for  instance,  represent  diagram- 
matically  a  synchronous  motor  operating  without  me- 
chanical load  and  with  the  normal  excitation  for  this 


FIG.       I        (a) — Dl.\r.R.\MM.\TI- 

CAL     REPRESENT.-^TION     OF 

SYNCHRONOUS    MOTOR 

Operating  without  me- 
chanical load  with  normal 
excitation. 


FIG.     I      (b) — MOTOR     OPERAT- 
ING    WITHOUT     MECHANICAL 
LOAD    WITH     INCREASED 
EXCITATION 

Size    of    circles    corre- 
sponds to  value  of  current. 


condition.  Assuming  the  theoretical  case  when  there 
are  no  losses  within  the  machine  itself,  the  armatufe 
current  will  be  zero;  so  that  the  only  source  of  m.m.f. 
is  the  current  in  the  field  windings  and  the  rotor  flux 
is  consequently  identical  with  the  equivalent  flux.  If, 
in  the  figure,  y-y  is  the  axis  of  flux  corresponding  to 
the  impressed  voltage,  the  rotor  must  take  up  the  posi- 
tion corresponding  to  this  axis,  as  indicated.  If  it  at- 
tempts to  take  up  any  other  position,  armature  currents 
will  flow  and  torques  will  be  produced  tending  to  return 
it  to  this  position  and  as  there  are  no  external  torques 
applied  to  the  shaft,  the  rotor  will  not  resist  these  re- 
straining forces. 

If  the  field  excitation  be  increased,  the  flux  will 
tend  to  increase  beyond  the  magnitude  of  the  equivalent 
flux,  and  as  a  consequence  an  armature  current  will 
flow  producing  a  m.m.f.  equal  and  opposite  to  the  in- 
crease in  field  m.m.f.  This  current  has  a  demagnetiz- 
ing effect  upon  the  field  and  will  assume  the  phase  posi- 
tion of  the  axis  x-x  at  right  angles  to  the  flux,  as  shown 
in  Fig.  I   (b).     On  account  of  this  phase  position  the 


current  can  produce  no  resultant  torque  and  conse- 
quently there  will  be  no  change  of  the  position  of 
the  rotor.  If,  on  the  other  hand,  the  field  excitation 
be  reduced  below  the  normal  value  the  opposite  action 
results,  the  armature  current  will  flow  in  the  reverse 
direction  and  become  magnetizing  instead  of  demag- 
netizing, but  still  counterbalancing  the  tendenc\  of  the 
flux  to  change  its  magnitude. 

It  will  be  observed  from  the  foregoing  that  when 
the  rotor  excitation  is  increased,  the  excess  of  magneti- 
zation beyond  that  of  the  equivalent  flux  cannot  be 
retained  within  the  machine  itself  but  is  transferred  in 
the  form  of  reactive  currents  to  the  external  circuit. 
When  the  motor  is  under-excited  the  reverse  is  true 
and  the  complementar}'  magnetization  is  drawn  from 
the  external  circuit.  This  property  is  utilized  in  the 
synchronous  condenser  for  controlling  the  power-factor 
of  distributing  and  transmission  systems  by  supplying 
them  with  magnetization  only.  Usually  the  condenser 
is  located  as  close  as  practicable  to  the  point  where  the 
magnetization  is  required.     The  synchronous  condenser 


FIG.    2     (a) — ROTOR    DISPL/\CED  FIG.    2     (b) — SYNCHRONOUS 

FROM    NO-LOAD    POSITION  CONDENSER    SUPPLYING     . 

DUE  TO  AN   APPLIED   ME-  MAGNETIZATION      TO 

CHANICAL    LOAD  THE    LINE 


is  simply  a  form  of  synchronous  motor,  except  that  the 
design  proportions  are  such  that  the  ratio  of  the  mag- 
netization supplied  externally  to  the  magnetization  re- 
quired within  the  machine  is  as  great  as  possible. 

When  a  mechanical  load  is  applied  to  the  shaft  of 
a  synchronous  motor  the  rotor  immediately  begins  to 
drop  back  in  phase  position.  The  action  is  quite  un- 
like the  "slip"  of  an  induction  motor;  for  in  the  latter 
case  the  speed  of  the  rotor  can  never  reach  synchronous 
?peed  and  the  torque  is  developed  only  by  the  continued 
dropping  back  of  the  rotor  behind  the  revolving  field 
and  is  a  function  of  the  resulting  dift'erence  of  velocity. 
In  the  case  of  a  synchronous  motor  changes  of  speed 
are  transient  and  occur  only  with  changes  of  load. 
When  stable  conditions  are  regained  the  speed  again 
becomes  synchronous  although  the  rotor  may  have  be- 
come permanently  displaced  with  respect  to  the  revolv- 
in<j  field.  The  torque,  on  the  other  hand,  is  a  function  of 
the  relative  phase  positions  of  the  rotor  and  the  revolv- 
ing field.  The  torque  increases  as  the  displacement  be- 
tween the  two  increases  until  a  maximum  or  pull-out 


March,    i<)2i 


THE  ELECTRIC  JOVRKAE 


value  is  reached.     This  point  is  taken  up  at  a  greater 
length  in  the  following  paragraphs. 

Fig.  2  (a)  represents  the  rotor  displaced  from  its 
no-load  position  due  to  an  a[)plied  mechanical  load. 
As  the  rotor  drops  back  it  tends  to  take  the  flux  with 
it;  therefore,  to  restore  the  flux  to  its  constant  equiva- 
lent value,  a  current  appears  in  the  armature,  increas- 
ing as  the  displacement  increases,  and  producing  an 
m.m.f.  just  equal  to  the  change  of  m.m.f.  caused  by  the 
rotor  displacement.  To  show 'this  in  a  more  definite 
manner  it  is  convenient  to  resolve  the  m.m.  f.'s  of  the 
armature  and  rotor  into  relative  components  along  the 
axes  x-x  and  y-y.  Since  y-y  is  the  axis  of  equivalent 
flux,  the  resultant  component  of  flux  and  m.m.f.  along 
x-x  must  be  zero ;  or,  in  other  words,  the  components  of 
m.m.f.  of  the  armature  and  the  rotor  along  this  axis 
must  counterbalance  each  other.  If  the  applied  voltage 
is  assumed  constant,  and  the  reluctance  of  the  magnetic 


FIG.    3 — ROTOR   DISPLACEMENT   AND  TOROUK   VCIK   VARIOUS   VALUKS   OK 
EXCIT.\TION   AND  CONSTANT   IM  PUKSSKll   VOLTAGE 

circuit  is  assumed  uniform,  the  resultant  m.m.f.  along 
y-y  must  be  constant.  Applying  these  two  limitations 
to  all  conditions  of  operation  the  internal  actions  and 
reactions  may  be  analysed.  It  will  be  seen  that  when 
the  rotor  drops  back,  its  m.m.f.  has  a  component  along 
the  x-x  axis  which  must  be  neutralized  by  the  m.m.f. 
of  a  current  flowing  in  the  armature  corresponding  in 
phase  to  the  axis  y-y.  This  current  is  directly  propor- 
tional to  the  field  excitation  multiplied  by  the  sine  of 
the  displacement  angle.  In  addition,  if  the  excitation 
be  normal  for  no-load,  its  y-y  component  will  be  in- 
.sufficient  for  the  amount  of  flux  required,  and  a  small 
component  of  armature  current  will  appear  at  x-x  to 
complete  the  magnetization  of  the  field.  The  actual 
current  in  the  armature  is  the  resultant  of  these  two 
components.  The  torque  produced  is  proportional  to 
that  component  of  armature  current  located  on  the  y-y 
axis,  for  it  is  placed  directly  in  the  flux.  This  compon- 
ent is  proportional  to  the  x-x  component  of  rotor 
m.m.f..  as  stated  above,  so  that  the  torque  is  also  pro- 
portional to  this  latter  value.     If  the  rotor  m.m.f.  be 


inciea>eil  it  will  take  a  correspondingly  smaller  dis- 
lilaceinent  to  give  the  same  torque-producing  compon- 
ent, and  the  rotor  will  move  slightly  forward.  Thus, 
for  a  given  torque,  the  displacement  depends  upon  the 
excitation;  -  the  greater  the  excitation,  the  less  the  dis- 
placement. 

In  addition  to  this  action,  when  the  excitation  is 
nicreased  the  magnetizing  component  of  the  armature 
current  may  decrease  to  zero  or  even  reverse  and  be- 
come demagnetizing  with  respect  to  the  rotor.  In  this 
manner  magnetization  may  be  supplied  to  the  line,  as  in 
the  case  of  the  synchronous  condenser.  Fig.  2   (b). 

In  Fig.  3,  the  curves  in  full  lines  show  the  relation 
lietween  displacement  and  torque  for  various  values  of 
excitation  with  a  smooth  rotor,  as  has  already  been  in- 
dicated. With  zero  excitation  no  torque  can  be  pro- 
duced by  synchronous  action  under  the  conditions 
assumed.  When  excitation  has  been  applied,  it  will  be 
seen  that  the  torque  increases  as  a  function  of  the  dis- 
placement (a  sine  function)  and  reaches  a  maximum 
value  when  the  displacement  is  90  degrees.     This  is  the 


FIG.    4— REACTIVE    lOMI'dNKXT   OF   AR.MATCRE  CURRENT   AT   POINT   OF 
PULL  OUT 

Producing  all  01  the  magnetization  for  the  equivalent  flux, 
point  at  which  the  whole  rotor  m.m.f.  is  acting  trans- 
versely and  so  causes  the  flow  of  the  maximum  torque- 
producing  component  of  armature  current.  If  this  dis- 
placement be  exceeded  the  transverse  component  of 
rotor  m.m.f.  will  decrease,  and  with  it  the  torque;  so 
that  the  motor  operates  in  an  unstable  condition.  The 
maximum  torque  is  called  the  pull-out  torque,  and  if 
this  be  exceeded  the  motor  will  come  to  rest.  The  pull- 
out  torque  is  proportional  to  the  field  excitation  and  to 
the  equivalent  flux,  regardless  of  the  power-factor  at 
the  motor  terminals.  Indeed,  at  the  point  of  pull-out, 
the  whole  of  the  magnetization  for  the  equivalent  flux 
is  produced  by  the  reactive  component  of  armature 
current.  Fig.  4,  just  as  is  always  the  case  for  an  induc- 
tion motor.  The  curves  of  Fig.  3  are  plotted  on  the 
assumption  of  a  constant  impressed  voltage.  If  this 
voltage  varies,  the  equivalent  flux  and  consequently  the 
pull-out  torque  will  vary  directly  with  it.  This  is  one 
point  of  difference  from  the  induction  motor,  where  the 
pull-out  torque  varies  as  the  square  of  the  impressed 
voltage.  When  running  on  reduced  voltage,  the  syn- 
chronous motor  will  have  a  relatively  greater  pull-out 
torque.  This  does  not  necessarily  mean,  however,  that 
a  synchronous  motor  should  be  used  on  systems  subject 


90 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


to  large  drops  in  voltage ;  for  while  the  pull-out  torque 
of  the  synchronous  motor  may  suffer  the  lesser  de- 
crease under  such  conditions,  its  speed  is  constant, 
while  that  of  the  induction  motor  will  drop  considerably 
as  the  load  is  increased  and,  in  the  case  of  motor-gen- 
erator sets  especially,  this  drop  in  speed  means  a  drop 


FIG.    S— RELATION     BETWEEN    TORQUE    AND    ROTOR    DISPLACEMENT 

For  given  values  of  armature  current,  when  the  load  and 
excitation  are  varied. 

in  the  torque  which  may  more  than  compensate  for  the 
extra  pull-out  torque  of  the  synchronous  motor.  In 
addition,  momentary  drops  of  voltage  will  have  far 
more  serious  effects  on  a  synchronous  motor,  for  if  it 
once  falls  out  of  step  there  is  less  tendency  for  it  to 
synchronize  again. 

Two  of  the  primary  assumptions  made  in  this 
analysis  should  be  taken  up  in  more  detail;  these  are, 
the  uniformity  of  the  reluctance  of  the  magnetic  cir- 
cuit, and  the  negligence  of  the  armature  leakage  fluxes. 


\ 

\ 

\ 

f 

\ 

\ 

I 

\ 

\ 

\ 

\ 

\ 

\ 

p 

J 

Leak 

" 

" 

enable  the  motor  to  operate  under  partial  load  at  syn- 
chronous speed.  Consider,  for  a  moment,  the  case  of 
a  load  being  applied  to  the  unexcited  motor.  The  flux 
is  caused  to  flow  by  a  magnetizing  current  located  on 
the  x-x  axis.  When  the  rotor  drops  back,  although 
the  m.m.f.  is  along  the  y-y  axis,  the  flux  will  tend  to 
take  a  path  more  nearly  coinciding  with  the  axis  of  the 
salient  poles  on  account  of  the  reduced  reluctance 
there.  Therefore,  to  force  the  flux  back  to  its  normal 
axis  the  torque-producfng  component  of  current  will 
appear  at  y-y.  The  maximum  dissymmetry  of  reluct- 
ance occurs  when  the  rotor  has  dropped  back  45  de- 
grees and  this  is  the  point  of  maximum  torque  beyond 
which  pull-out  occurs.  This  maximum  torque  is  de- 
pendent upon  the  ratio  of  reluctances  of  the  magnetic 
path  with  the  rotor  in  the  two  extreme  positions  90  de- 
grees apart.  Some  motors  can  be  loaded  up  to  30  or 
40  percent  or  their  normal  rated  loads  without  pulling- 
out,  although  the  corresponding  torques  are  a  much 
smaller  percentage  of  the  actual  pull-out  torques  in  the 
excited  condition.     The  effect  of  this  non-uniform  re- 


FIG.   6 — RELATION    BETWEEN    TORQUE    AND    PERCENT    LEAKAGE 

For  a  given  excitation  and  rotor  displacement. 
Practically  all  synchronous  motors  are  of  the 
salient  pole  type,  so  that  the  reluctance  of  the  magnetic 
circuit  taken  at  a  point  directly  under  the  pole  is  con- 
siderably less  than  when  taken  in  the  interpolar  space. 
This  non-uniformity  of  reluctance  can  produce  a  re- 
action even  when  the  rotor  is  unexcited,  which  may 


<" 

, — 

/ 

y 

1 

Normal     ./votagt   '          j   %^i^ 

lb/          '           .    Jt^       \          \ 

f. 

X   j?/\ 

1 

J/' 

N;^ 

fi^  '^ 

V 

1 

^/ 

1      1 

f 

/ 

§ 

j\ 

i 

7 

1 

/j 

Field  Atniperes 

i 

FIG.    7 — NO-LOAD    AND    FULL-LOAD    ZERO    PERCENT    POWER-FACTOR 
SATURATION   CURVES 

luctance  shows  itself  even  when  the  rotor  is  excited,  as 
is  indicated  by  the  curves  of  Fig.  3  in  dotted  lines. 
These  curves  show  that  the  angle  of  pull-out  varies 
with  the  excitation,  and  that  the  form  of  the  curve  in 
the  stable  and  unstable  portions  is  unsymmetrical. 

The  second  assumption  requiring  special  attention 
is  that  there  is  no  armature  leakage  flux.  This  flux  is 
set  up,  in  the  actual  motor,  by  the  armature  current 
alone,  in  paths  distinct  from  the  magnetic  circuit  of  the 
rotor,  and  which,  for  a  given  armature  current,  is  al- 
most entirely  unaffected  by  changes  of  rotor  excitation 
or  phase  positions.  Because  of  this  it  is  not  instru- 
mental in  the  production  of  torque,  and  simply  repre- 
sents a  definite  amount  of  magnetization  in  the  machine 
proportional  to  the  current. 

The  main  result  of  leakage  is  the  reduction  of 
armature  reaction  and  torque.  Take,  for  instance,  the 
explanation  referring  to  Fig.  2  (a).  It  was  stated  that  as 
the  rotor  became  displaced  its  m.m.f.  component  along 
x-x  must  be  counterbalanced  by  an  armature  m.m.f.  to 
bring  the  air-gap  flux  back  to  its  constant  position  in 


March,  1921 


THE   ELECTRIC  JOURNAL 


91 


space.  When  leakage  is  present,  however,  the  armature 
counter  m.m.f.  exerted  need  be  sufficient  only  to  bring 
the  flux  part  way  back,  the  remaining  difference  be- 
tween the  air-gap  flux  and  the  equivalent  flux  being 
made  up  by  the  leakage  flux  in  external  paths.  Thus 
for  a  given  rotor  excitation  and  displacement  the  arma- 
ture counter  m.m.f.  and  current,  and  the  resulting  tor- 
que all  decrease  with  an  increase  in  the  rnagnetic  leak- 
age of  the  armature.  If,  with  the  rotor  unexcited  and 
with  a  given  armature  current,  the  ratio  of  the  leakage 
flux  to  the  total  flux  be  known  as  the  percent  leakage, 
the  decrease  in  torque  for  a  given  excitation  and  dis- 
placement is  in  a  direct  proportion  to  the  percent  leak- 
age, as  is  indicated  by  Fig.  6.  This  means  that  to  ob- 
tain a  given  pull-out  torque,  a  machine  having  a  greater 
percent  leakage  must  be  supplied  with  correspondingly 
increased  excitation  over  that  supplied  to  a  motor  with 
a  smaller  leakage.  This  relation  is  much  more  fre- 
quently' considered  in  connection  with  induction  motors 
than  with  synchronous  motors,  but  it  is  equally  ap- 
plicable in  either  case. 

Leakage  reactance  acts  in  exactly  the  same  way  as 
a  reactance  external  to  the  machine.  Thus,  if  there  be 
a  reactance  intervening  between  the  source  of  constant 
voltage  and  the  motor  terminals,  the  total  reactance  of 
this  and  the  internal  leakage  should  be  added  together 
to  find  the  decrease  of  torque.  In  certain  instances  the 
intervening  reactance  between  two  synchronous  ma- 
chines or  systems  of  synchronous  machines  has 
reached  so  great  a  value  that  the  maximum  synchroniz- 
ing power  which  can  be  transmitted  is  insufficient  to 
prevent  serious  hunting  of  one  with  respect  to  the  other. 

Fig.  7  shows  more  clearly  what  is  meant  by  the 
term  "percent  leakage".  This  diagram  represents  the 
no-load  and  full-load  zero  percent  power-factor  satura- 
tion curves  for  a  synchronous  motor.  The  triangle 
abc  \s  what  is  generally  known  as  Potier's  triangle,  by 
which  in  some  measure  the  leakage  reactance  and  the 
reaction  may  be  segregated.*  If,  then,  ab  is  a  measure 
of  the  leakage  fluxes  and  hd  a  measure  of  the  total 
fluxes  due  to  the  armature  current  alone,  then  the  ratio 

—rj—  is  the  percent  leakage  flux,  and  the  torque 

under  the  conditions  will  be  decreased  in  the  ratioi-V^  . 

0(7 

In  considering  reaction  and  armature  reactance, 
perhaps  the  simplest  theoretical  distinction  can  be 
drawn  from  the  fact  that  reaction  is  a  necessary  ad- 
junct in  the  production  of  torque,  while  reactance  al- 
ways tends  to  decrease  it.  It  must  not  be  considered 
that  internal  reactance  is  wholly  undesirable.  It 
serves  the  purpose,  in  any  synchronous  machine,  of  re- 
ducing the  initial  rush  of  current  on  occasions  of 
short-circuit. 


p.  60 


■See  artical  by  the  Author   in  the  Journal   for  Feb.   21, 


The  curves  of  Fig.  5  are  drawn  to  show  the  rela- 
tion between  torque  and  displacement  for  given  values 
of  armature  current  when  the  mechanical  load  and  ex- 
citation are  varied.  It  is  clearly  indicated  that  unless 
the  armature  current  increases  beyond  a  definite  value, 
which  is  the  amount  required  for  self  excitation  under 
the  pull-out  condition,  the  motor  will  not  pull-out.  As 
long  as  the  field  current  is  greater  than  that  required 
for  unity  power-factor,  the  motor  cannot  pull-out. 

A  high  ratio  of  pull-out  torque  to  normal  or  rated 
torque  is  generally  desirable,  and  in  cases  of  motors 
subject  to  sudden  heavy  overloads  it  is  necessary.  As 
the  pull-out  torque  depends  upon  excitation  it  means 
that  for  the  condition  of  normal  load  the  excitation 
must  be  relatively  high  when  compared  with  the  amount 
actually  required  from  other  considerations;  or,  in 
other  words,  the  rotor  displacement  at  the  normal  load 
must  be  relatively  small.  In  relation  to  design  this 
tends  to  produce  a  rather  larger  machine  than  would 
otherwise  be  required.  The  inherent  stability  may 
thus  be  obtained  by  one  of  the  following  methods ;  first, 
takmg  the  larger  machine  and  simply  under-rating  it; 
second,  designing  a  machine  of  more  nearly  ordinary 
proportions  but  with  an  exceptionally  wide  air-gap  in 
which  to  consume  the  extra  excitation.  Where  mag- 
netization would  be  of  service  to  the  external  system 
in  raising  its  power-factor,  the  latter  condition  is  in  a 
broad  sense  wasteful  of  excitation,  for  it  is  using  up 
magnetic  energy  in  the  increased  air-gap  which  might 
be  transferred  to  the  external  system.  The  third 
method,  then,  is  to  design  the  machine  to  carry  the  re- 
active components  of  current  and  to  operate  it  at  a  lead- 
ing power- factor  (with  respect  to  the  system).  This 
will  also  insure  a  high  power-factor  even  on  severely 
heavy  overloads. 

In  certain  instances  of  late  a  scheme  of  over-com- 
pounding the  excitation  has  been  used  in  the  case  of 
motor-generator  sets,  especially  those  intended  for 
railroad  substation  service.  The  motor  is  excited  by  a 
separate  exciter  furnished,  in  addition  to  a  shunt  field 
winding  with  a  series  field  winding  energized 
by  the  main  current  from  the  direct-current 
generator,  and  in  this  way  the  exciter  voltage 
rises  automatically  with  increases  of  load.  The  result- 
ing increase  of  field  current  in  the  motor  renders  the 
inherent  pull-out  torque  a  function  of  the  load  applied 
to  the  motor. 

In  the  design  of  synchronous  condensers  no  par- 
ticular attention  need  be  paid  to  the  pull-out  torque,  for 
the  machine  is  intended  to  be  operated  with  little  or  no 
mechanical  load.  On  this  account  the  air-gap  may  be 
made  relatively  smaller  than  for  a  synchronous  motor, 
unless  special  conditions  of  operation  with  greatly  re- 
duced excitation  are  contemplated,  when  the  air-gap 
must  be  made  great  enough  to  ensure  stability  under 
the  worst  operating  condition. 


Experience  In  ^i'yiiig  ^^"^^ 


ruiors 


W'l'stinghousc 

ENGINEERS   are    frequently  obliged   to   dry   out 
high-voltage  transformers  when  the  only  avail- 
able method  is  by  external  heating.     There  are 
two  ways  by  which  this  can  be  accomplished: — 

/ — Drying  the  transformer  assembled  in  its  case. 
2 — Drying   the    transformer    outside   its    case,    and  .is- 
sembling  it  after  it  has  been  dried. 

This  article  deals  with  an  experience  the  writer  had 
in  France,  in  drying  out  a  number  of  6000  kv-a,  single 


S.  H.  ABBOTT 

Electric   Internationa 


Company 

fuses    and    switches.      One    resistance    was    connected 
in    delta,    another    in    star    and    the    other    in    uneven 
Z,  so  that,  by  opening  switches  or  removing  fuses,  any 
regulation  of  temperature  could  be  made.     The  total 
power  used  in  this  case  was  approximately  75  kw. 

The  wooden  conduit  connecting  the  resistance  box 
to  the  conduit  under  the  transformer  was  made  double 
for  conservation  of  heat.  Removable  covers  were  made 
to  the  double  conduit  and  resistance  box,  in  order  that 


phase,  10  000  to  70  000  volt,  oil  insulated,  water  cooled  ^j^^  interiors  might  be  accessible.     The   resistance   box 

transformers  at  two  outdoor  sub-stations.  gri^j  conduit  were  lined  with  asbestos,  as  far  up  as  the 

The   transformers   in   question   had   been  enroute  transformer  case.     This  reduced  the  fire  risk  and  also 

from  Pittsburgh,  or  outdoors  in  their  packing  cases  at  kept  the  heat  where  it  was  most  needed, 
customer's  station  for  two  years.     Prior  to  the  writer  s  Common  window  screen,  built  into  a  frame,  so  ih.u 

arrival,  the  contractor  had  attempted  to  diy  out  these  it  could  be  removed  for  cleaning,  was  placed  at  the  in- 

transformers  by  blowing  hot  air  through  a  hole  at  one  takg  to  the  fan  and  at  the  entrance  to  the  resistance  box. 

end  of  the  packing  case  and  an  outlet  at  the  other,  with  Another    window    screen    was    constructed    in    a    deep 

the  transformers  on  their  sides.     He  succeeded  in  burn-  frame  next  to  the  resistance,  on  the  fan  side.     This  sys- 


ing  out  two  transformers.  The  writer  used  successfully 
the  second  method  mentioned  above. 

Each  station  has  a  small  transformer  house  pro- 
vided with  a  hoist  for  assembling  and  repairing  the 
transformers.  Each  assembled  transfomier  is  fur- 
nished with  wheel  bases,  by  means  of  which  it  is  pushed 
from  its  foundation  onto  a  special  truck,  which  is  on  a 
track  leading  into  the  transformer  house.  Two  trucks 
were  available  at  each  station. 

A  transformer  core  was  removed  from  its  packing 
case  and  the  packing  case  bottom  with  its  heavy  timber 
was  placed  upon  one  of  the  trucks.  In  the  center  of 
this  bottom,  between  the  timbers,  a  square  hole  was  cut. 
A  wooden  conduit  was  then  built  between  the  timbers, 
around  three  sides  of  the  hole,  and  out  to  one  end, 
where  it  connected  with  a  larger  double  wooden  con- 
duit, which  extended  into  the  box  containing  the  resist- 
ance. At  the  end  of  the  resistance  box  (which  ex- 
tended two  feet  beyond  the  resistance)  a  motor-oper- 
ated fan  was  placed,  as  shown  in  Fig.  i. 

The  transformer  core  was  placed  right  side  up, 
over  the  hole  on  the  truck,  and  enclosed  tightly  in  a 
wooden  case.  The  case  had  four  detachable  sides  held 
together  by  bolts  as  shown,  so  that  it  could  easily  be 
assembled  and  used  for  all  transformers.  The  top  of 
the  case  had  holes  to  allow  for  the  escape  of  air.  Two 
doors  were  constructed  at  the  bottom  and  one  near  the 


tern  compelled  the  air  to  pass  through  the  renter  of  the 


■^ 


FIG.    I — ARRANGEMENT    OF    APPARATUS    FOR    DRYING    OUT    LAR<^i; 
TRANSFORMERS 

resistance,  instead  of  around  the  edges,  and  thereby  in- 
creased the  uniformity  of  heat.  A  hinge  door  was 
placed  at  the  intake  to  fan,  which  was  raised  and 
lowered  to  regulate  the  volume  of  air. 

In  the  double  conduit,  as  shown,  were  placed  two 
screens  of  fine  copper  wire,  in  sliding  frames.  It  was 
found  necessary  to  remove  and  clean  these  screens,  at 
least  every  other  day.  Otherwise,  dust  collecting  on 
the  screens  would  retard  the  air  and  cause  a  greater  dif- 
ference in  temperature  between  the  resistance  and  the 
transformer  case. 

At  first,  it  was  found  that  the  temperature  of  the 
air  entering  the  transformer  case  varied  greatly  at  dif- 


ferent points^to  such  an  extent  that  the  air  at  the 
top  of  the  case  to  allow  for  observation'  of  temperature,  hottest  point  would  have  to  be  dangerously  hot  in  order 
etc.  to     heat     the     coils     sufficiently.     To     eliminate     this 

condition,  baffle-plates  were  arranged  in  the  double  con- 
duit, as  shown.  Then  at  no  place  of  entrance  to  the 
transformer  case  did  the  temperature  of  the  air  vary 
more  than  one  or  two  degrees.  The  temperature  of  the 
air    entering    the    double    conduit,    of    course,    varied 


The  resistance  used  was  "home-made",  iron  wire 
being  coiled  into  spirals  and  strung  over  spool  insula- 
tors. Each  unit  (there  being  one  unit  at  each  station) 
consisted  of  three  similar  resistances,  and  each  resist- 
ance was    connected    to    a    three-phase    line   through 


March,  1921 


THE  ELECTRIC- JOURNAL 


more— the  hottest  current  being  near  the  center  of  the 
entrance. 

With  the  above  system  in  operation,  the  following 
results  were  easily  obtained  with  a  fan  of  about  2000 
cubic  feet  per  minute  capacity.  The  average  tempera- 
ture of  the  air  leaving  the  resistance  was  from  one  to 
two  degrees  higher  than  the  air  entering  the  trans- 
former case,  which  was  kept  around  85  degrees  C.  The 
coil  temperature  was  from  70  to  80  degrees  C.  The 
temperature  of  the  coils  at  the  top  was  not  more  than 


93 

two  degrees  lower  than  the  temperature  at  the  bottom. 
The  screens  kept  dust  from  entering  the  transformer 
and  the  heat  was  so  well  placed  that  the  observers  were 
obliged  to  have  extra  heat  in  the  room  to  keep  warm. 

Wires  were  placed  on  insulators  at  the  top  of  the 
transformer  case  and  passed  through  holes  in  the  top 
and  connected  to  the  windings  and  iron  for  testing  pur- 
pose. Each  transformer  was  dried  out  for  about  a 
month  untd  the  megohms  resistance  had  attained  a  safe 
and  constant  value. 


lio  .DDvelofimeiiJ  ©f  MaKinoik  ,iV(ai:o 


T.  D.  YENSEN 

Research   Laboratory, 
Westinghouse  Electric  &   Mfg.   Company 


irials 


THE  MATERIAL  used  by  the  pioneers  in  the  field 
of   electromagnetism   was  naturally   the   iron  al- 
ready available  at  the  time,  either  cast  iron  or 
wrought  iron.     Some  grades  were  found  to  be  better 
than  others,  thus  soft  wrought  iron  was  found  to  have 
better  magnetic  properties  than  iron  high  in  carbon,  and 
the  lower  the  carbon  content  the  better.     Swedish  char- 
coal iron  was  considered  the  best  iron  for  magnetic  pur- 
poses during  the  latter  part  of  the  19th  century.     The 
introduction  of  the  Bessemer  process  did  not  alter  this 
situation,  and  it  was  only  the  coming  of  the  modern 
open  hearth  furnace  that  enabled  steel  makers  to  pro- 
duce a  material  equal  in  magnetic  properties  to  the  old 
Swedish  iron.     The  temperature  produced  in  this  fur- 
nace was  high  enough  actually  to  melt  pure  iron  and 
this  could  be  poured  into  ingot  forms,  thus  producing 
what   was   called   ingot  iron.     The  various   grades   of 
iron,  as  tested  by  Ewing  and  others,  would  have  a  maxi- 
mum magnetic  permeability  of  2-3000  and  a  hysteresis 
loss  of  3-5000  ergs  per  c.c.  per  cycle  for  B  =  10  000 
and,  on  account  of  the  low  electric  resistance,  would 
have  a  high  eddy  current  loss. 

This  was  the  situation  at  the  close  of  the  nineteenth 
century  at  the  time  when  the  development  of  elecro- 
magnetic  machinery  was  increasing  at  a  tremendous 
rate.  For  dynamo-electrical  machinery  the  magnetic 
properties  of  the  existing  materials  caused  little  trouble, 
for  the  simple  reason  that  the  large  air-gap  in  the  mag- 
netic circuit  is  the  all  important  factor  in  the  determina- 
tion of  its  equivalent  permeability,  and  the  mechanical 
losses  due  to  rotation  largely  influence  the  efficiency  of 
the  machine.  Consequently,  while  iron  with  high  per- 
meability and  low  losses  is  desired,  it  could  not  greatly 
improve  the  performance  of  this  class  of  machine.  This 
IS  proved  by  the  fact  that  even  today  the  designers  of 
motors  and  generators  are  satisfied  with  low  silicon 
steel. 

Wilh  transformers,  however,  the  story  is  very  dif- 
terent.     Here  there  is  a  closed  magnetic  circuit  with  no 


moving  parts,  so  that  its  performance  depends  entirely 
upon  the  characteristics  of  the  iron,  considering  those 
of  the  copper  constant.     Even  the  earliest  transformers 
were  built  with  thin  sheets  for  the  cores,  in  order  to  cut 
down  the  eddy  currents,  but  other  than  that  no  great 
improvement  was  made  for  some  time.     The  best  trans- 
former sheet  was  made  from  Swedish  charcoal  iron 
having  a  maximum  permeability  of  2800  and  a  hystere- 
sis loss  of  3400  ergs  per  c.c.  cycle. '  Another  material 
was   developed   in   England    (by  J.    Sankey  &   Sons) 
called  "Lohys"  having  a  maximum  permeability  of  2800 
and  a  hysteresis  loss  of  about  3000  ergs  per  c.c.  per 
cycle  (a  total  iron  loss  of  3.56  watts  per  kg  for  B  = 
10 000  at  60  cycles).  The  aging  properties  of  these  ma- 
terials   were    such    that    the    losses    would    sometimes 
double  in  a  few  months,  necessitating  dismantling  the 
transformer  and  reannealing  the  iron.     If  this  was  not 
done  the  energy  losses  rose  to  10  or  15  percent  of  the 
capacity  of  the  transformer^. 

This  condition  of  affairs  attracted  the  attention  of 
one  of  the  greatest  steel  makers  of  his  time,  Robert  A. 
Hadfield  of  Sheffield,  England.  Prior  to  1865  iron 
metallurgy  was  confined  exclusively  to  the  combination 
of  iron  and  carbon.  In  1882  Hadfield  commenced  an 
investigation  of  the  effect  of  other  elements  upon  the 
mechanical  properties  of  iron,  in  the  course  of  which 
he  discovered  the  famous  manganese-steel,  cr.itaining 
12  percent  Mn,  and  possessing,  after  qiu-ching, 
unusual  strength  combined  with  wonderful  toughness 
(the  elongation  amounting  to  100  percent).  Another 
unusual  property  of  this  alloy  was  that  it  was  non-mag- 
netic at  ordinary  temperatures,  and  was,  therefore,  ad- 
mirably adapted  for  use  in  the  proximity  of  compasses 
on  shipboard.  His  contribution  to  the  development  of 
armor  plate  and  armor  piercing  projectiles  has  been  of 
vast  importance  and  was  the  result  of  his  research  work 
on  iron  alloys  of  many  different  types,  including  nickel, 
chromium,   tungsten,   cobalt,   molybdenum  and  others.' 

I     Hadfield:     History  of  the  Metallurgy  of  Iron  &  Steel— 
Proc.  Inst.  Mech.  Engrs.  Feb.  8,  1915,  p.  332 


94 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


High  speed  steel  also  owes  its  existence  parti}-  to  Had- 
field's  research  work. 

It  was  not  surprising  then,  that  it  was  Hadfield 
who  should  help  solve  the  difficulty  of  the  electrical  en- 
gineers in  their  development  of  the  transformer,  due 
to  the  poor  magnetic  quality  of  the  iron  then  available. 
With  his  usual  desire  for  thoroughness  he  associated 
•with  him  Professor  Barrett  of  the  University  of  Dublin, 
who  was  an  expert  in  the  field  of  electro-magnetism. 
Between  1895  and  1900  they  investigated  the  magnetic 
properties  of  all  conceivable  simple  combinations  of 
iron,  with  the  available  elements.  A  great  many  of 
these  alloys  were  already  available  from  Hadfield's  in- 
vestigations of  the  mechanical  properties  during  the 
previous  decade,  but  numerous  others  were  prepared  at 
this  time.  The  results  were  published  in  1900  and 
1902I  While  many  interesting  alloys  were  developed, 
only  two  appeared  to  be  of  commercial  value,  the  ferro- 
aluminium  and  the  ferrosilicon  alloys.  Both  of  these 
alloys  showed  greater  permeability  and  lower  hysteresis 
loss  than  the  best  Swedish  charcoal  iron.  Further- 
more, the  electrical  resistance  of  the  four  percent  alloys 
was  five  times  that  of  the  unalloyed  iron,  thus  decreas- 
ing eddy  current  losses  to  an  almost'  negligible  factor. 
On  account  of  the  greater  ease  with  which  the  silicon 
alloys  could  be  made,  efforts  were  concentrated  on  these 
rather  than  on  the  aluminium  alloys.  Four  percent 
silicon-steel  was  prepared  and  rolled  into  sheets,  20  mils 
thick,  and  tests  of  these  gave  a  permeability  about  25 
percent  higher  than  that  of  the  Swedish  iron  (  fi  max 
=  3600),  a  hysteresis  loss  of  about  two-thirds  that  of 
the  pure  iron  (1.7  watts  per  kg.  at  60  cycles  =  2100 
ergs  per  c.c.  per  cycle  for  B  =  10  000),  and  an  elec- 
trical resistance  five  times  that  of  the  pure  iron  (about 
60  microhms  per  c.c).  Furthermore,  and  this  was  just 
as  important,  the  aging  was  nil. 

The  first  transformer  using  this  new  material, 
called  "Stalloy",  was  built  in  1903,  and  weighed  30 
pounds.  This  was  followed  by  a  40  kw  and  a  60  kw 
transformer  that  have  been  in  constant  service  ever 
since.  The  original  core  loss  of  the  former  was  176 
watts,  and  this  was  decreased  to  131  watts  after  seven 
years  service.  Its  weight  was  830  pounds  instead  of 
1 1 20  pounds  for  a  transformer  of  the  same  capacity 
made  from  "Lowhys"  iron.  It  was  estimated  that  dur- 
ing those  seven  years  the  transformer  had  saved  the 
company  using  its  8700  kw-hours  or  $117.50  (with 
power  at  1.3  cents  per  kw-hr.).  Another  illustration 
showing  the  possibility  of  reducing  the  weight,  and 
thereby  the  cost  of  transformers  is  found  in  the  case 
of  a  60  kw  transformer  that  could  be  put  into  a  40  kw 
tank. 

Hadfields  first  patent  application  was  filed  in  the 

2  Barrett,  Brown  &  Hadfield :  Conductivity  &  Magnetic  Pro- 
perties of  Iron  Alloys. 

Proc.  Royal  Dublin  Socit-ty     7,  pp    67-126,  Jan.  1900 
Trans.  Royal  Dublin  Society  8,  pp.     1-22,  Sept.1902 
Jour.  Inst.    Elect.    Engrs.    31,  pp  674-721,   .Apr.   1902 


United  States  on  June  12,  1903  and  the  patent  was 
granted  December  i,  I903'*.  This  patent,  therefore,  ex- 
pired quite  recently. 

Considering  the  introduction  of  silicon-sleel  in  this 
country,  while  the  first  transformer  using  silicon-steel 
in  England  was  built  in  1903,  it  was  three  years  before 
the  news  had  reacted  upon  the  minds  of  the  manufac- 
turers in  this  country  sufficiently  to  lead  to  action.  The, 
steel  was  recognized  as  revolutionary. in  its  effect  upon 
the  characteristics  of  the  transformer,  it  was  talked 
about  and  written  about,  and  its  use  urged  by  those  in 
position  to  know,  but  adoption  required  financial  invest- 
ment, change  of  designs  and  change  in  methods  of 
manufacture,  all  of  which  had  to  be  carefully  con- 
sidered before  the  manufacturer  could  feel  warranted 
in  taking  the  step.  Finally  in  the  early  part  of  1906 
the  reaction  took  place  with  such  force  that  before  the 
year  was  half  gone,  not  only  was  silicon-steel  made  in 
this  country  but  the  first  transformers  were  on  the 
market.  The  steel  companies  associated  with  the  large 
electrical  manufacturers  obtained  licenses  to  make 
silicon-steel  under  the  Hadfield  patent,  but  the  license 
to  make  the  steel  did  not  carry  with  it  a  disclosure  of 
the  process  of  manufacture,  and  consequently  it  was 
necessarj'  for  each  steel  mill  to  develop  its  own  process. 
The  large  electrical  manufacturers  were  actively 
interested  in  this  development  and  intensive  work  was 
carried  on  in  the  spring  of  1906.  Many  were  the  fail- 
ures, and  the  quantity  of  expensive  steel  sent  to  the 
scrap  heap  was  measured  in  hundreds  of  tons.  But  in 
spite  of  all  kinds  of  mishaps  the  work  progressed  and 
at  the  end  of  three  months  of  intensive  work  the  first 
sheets  of  four  percent  silicon-steel  were  ready  for  the 
transformer.  Since  that  time  America,  and  all  the 
world  for  that  matter,  has  paid  tribute  to  Hadfield  both 
in  the  form  of  recognition  and  license. 

In  1910  Dr.  Morton  C.  Lloyd  of  the  Bureau  of 
Standards  at  Washington  in  a  paper  before  the  Frank- 
lin Institute,  Philadelphia,  estimated  that  at  that  time 
silicon-steel  was  saving  the  United  Sates  something  like 
ten  million  dollars  worth  of  electrical  energy  annually. 
What  the  total  saving  to  the  world  has  been  during  the 
17  years  that  the  patent  has  been  in  force  it  is  difficult 
to  even  guess,  but  taking  the  above  figure  as  an  average 
for  the  United  States  and  doubling  it  for  the  world  as  a 
w-hole,  we  get  as  a  conservative  total  for  the  world  for 
17  years  the  sum  of  340  million  dollars,  nearly  enough 
to  build  the  Panama  Canal. 

Since  the  introduction  of  silicon-steel  a  great  deal 
of  investigational  work  has  been  done  to  obtain  even 
better  magnetic  materials.  The  work  of  Gumlich*  ex- 
tending over  two  decades,  deserves  especial  mention. 
He  was  largely  instrumental  in  introducing  silicon-steel 
in  Germany.'  Burgess  and  Aston^  of  the  University  of 
Wisconsin  investigated  a  large  number  of  iron  alloys 
using   electrolytic   iron    as    a   base.     They    found    that 

3  U.  S.  Patent  No.  745  829. 


March,   1921 


THE  ELECTRIC  JOURNAL 


95 


silicon,  arsenic  and  tin  improved  the  magnetic  proper- 
ties, but  that  other  elements,  like  copper,  manganese, 
antimony  and  nickel  decrease  the  magnetic  properties. 
A  few  of  the  other  investigators  are  Baker'  in  England, 
Paglianti*  in  France,  Hunter'  at  Rensselaer  Polytechnic 
Institute  and  Honda  in  Japan.  In  spite  of  all  this 
work,  however,  silicon-steel  is  used  today  exclusively 
for  transformers  and  is  coming  into  use  more  and  more 
extensively  even  for  motors,  and  generators.  Manu- 
facturing processes  have  been  improved  and  modified, 
and  better  raw  materials  are  obtainable  now  than  17 
years  ago,  as  a  result  of  which  the  energy  losses  of 
[iresent  day  four  percent  silicon-steel  are  only  slightly 
in  excess  of  one  watt  per  kg.  instead  of  two  watts  per 
kg.  as  obtained  by  Hadfield  in  1903,  and  the  permea- 
bility is  8000  instead  of  3600. 

That  there  is  still  room  for  improvement  is  shown 
by  the  results  of  the  investigations  that  it  was  the 
author's  privilege  to  direct  at  the  University  of  Illinois 
between  1912  and  1916,^°  and  by  the  further  investiga- 
tions that  have  been  made  at  the  Westinghouse  Re- 
search Laboratory  since  1916.  By  refined  methods  of 
preparation  and  subsequent  heat  treatments  by  the  use 
of  vacuum,  ferrosilicon  alloys  have  been  produced  that 
have  a  maximum  permeability  of  40000  or  more  (in- 
stead of  8000)  and  a  hysteresis  loss  of  300  ergs  per  c.c. 
per  cycle  for  B  =  10  000  (instead  of  1500  ergs).  Ways 
and  means  have  also  been  found  of  so  treating  commer- 
cial silicon-steel  in  bar  form  as  to  impart  to  it  these 
superior  properties.  This  treatment  consists  of  remov- 
ing the  carbon  (about  0.05  percent)  from  the  commer- 
cial steel  to  a  point  well  below  o.oi  percent  by  anneal- 
ing under  oxidizing  conditions.  Patents  have  been 
granted  both  on  the  product  having  the  superior  mag- 
netic properties,"  mentioned  above,  and  on  the  method 
of  discarbonizing  the  commercial  steel. '^ 

MATERIAL  FOR  HIGH  FLUX  DENSITIES 

Thus  far  magnetic  materials  for  transformers  have 
been  considered,  for  the  reason  that  this  is  the  only 
commercial  apparatus  in  which  a  high  grade  magnetic 
material  is  of  sufficient  value  to  warrant  the  cost. 
There  are,  however,  certain  parts  of  dynamo  machinery 
in  which  improvements  in  the  characteristics  of  present 
day  material  would  be  highly  appreciated,  such  as  arma- 
ture teeth  and  pole  tips  in  which  the  magnetic  induc- 
tion runs  very  high  and  imposes  a  lower  limit  upon  the 

4  E.T.Z.,  June  26,  July  3,  10,  17,  igrp. 

5  E.T.Z.,  22,  p.  691,  1901. 

6  Met.  &  Chem.  Eng.   1910. 

7  }.  Iron  &  Steel  Inst.  64,  p.  312,  1903.     /.  Inst.  Elect.  Engrs. 
34,  p.  498,   1904-S 

8  Metallurgie  g,  p.  217,  1912. 

9  Am.  Electrochcm.  Soc.  Apr.  8-10,   1920, 

ro  Bulletins  Nos.  72,  77>  83  and  95  of  the  Eni?.  Exp.  station, 
Lniv.  of  111. 

"  H-  ?•  Patents  1,277,523  and  1,277,524,  Sept.  3,  1918. 
12  U.  S.  Patent  1,358,810,  Nov.  16,  1920. 


amount  of  material  used.  Low  hysteresis  loss  and  high 
maximum  permeability  are  of  secondary  importance  in 
this  case.  What  is  needed  is  a  material  having  high 
permeability  at  high  flux  densities.  The  best  material 
available  today  is  the  purest  commercial  iron,  iron  as 
free  from  oxide  and  other  impurities  as  possible.  It 
was  thought  for  a  long  time  that  no  other  material  had 
a  higher  saturation  value  than  pure  iron,  and  it  was  not 
until  Dr.  P.  Weiss'^  of  Zurich  in  1912  showed  that  an 
alloy  of  the  composition  Fe,  Co  has  a  saturation  value 
ten  percent  higher,  that  scientists  changed  their  minds. 
The  FeCo  alloys  have  since  been  further  investigated, 
confirming  Dr.  Weiss'  results,  and  data  were  obtained 
of  permeability  and  hysteresis  loss  for  alloys  containing 
from  zero  to  34.5  percent  cobalt,  showing  that  the 
latter  would  be  admirably  suited  for  armature 
punchings.  However,  there  is  one  serious  drawback. 
The  alloy,  at  the  present  prices  of  cobalt,  would  cost 
between  50c  and  $1.00  per  pound,  which  is  prohibitive, 
and  it  is  doubtful  whether  the  cost  will  ever  come  down 
to  a  point  where  it  can  be  generally  used.  The  third 
element  in  the  same  class  with  iron  and  cobalt,  namely 
nickel,  lowers  the  ultimate  saturation  value,  but  it  has 
been  found  that  a  nickel  content  of  5  to  7  percent 
raises  the  permeability  for  high  inductions  by  about  five 
percent,  and  this  alloy  may  therefore  come  into  use  to  a 
limited  extent. 

PERMANENT  MAGNET  MATERIAL 

.In  the  field  of  permanent  magnets  there  has  been  a 
great  deal  of  new  development  in  late  years".  High 
carbon  steel  (i  to  1.5  percent  C)  was  used  until  the 
discovery  of  tungsten  steel  about  1910,  containing  five 
to  six  percent  tungsten  and  one-half  percent  carbon. 
The  war  brought  about  a  tungsten  famine  and 
chromium  was  substituted  with  partial  success.  For- 
tunately, new  sources  of  tungsten  were  found  and  tung- 
sten steel  has  been  used  ever  since.  However,  a  new 
steel  has  been  discovered  recently  containing  for  the 
best  results  35  percent  Co,  7  to  9  percent  W  or  Mo  and 
0.5  percent  C.  It  may  or -may  not  contain  Cr.  This 
steel  is  very  hard  and  difficult  to  work  but  is  such  an 
improvement  upon  the  previous  steels  that  it  may,  in 
spite  of  this  disadvantage,  succeed  in  conquering  the 
field.  It  is  peculiar  in  that  it  must  be  quenched  at  iioo 
degrees  and  must  be  initially  magnetized  in  a  very 
strong  field  (H  =  500  or  more)  before  the  advantage 
over  tungsten  steel  appears.  But  once  so  treated  it  has 
a  coercive  force  of  200  gilberts  as  compared  to  70  for 
tungsten  steel  and  40  for  carbon  steel.". 


13  Comptes  Rcndus,  156  p.  1970,  1913. 

14  S.  P.  Thompson :  Steel  for  Permanent  Magnets.  Jour.  Inst 
of  Elect.  Engrs.  50,  p.  80,  1913. 

15  Patents  have  recently  been  granted  to  Dr.  K.  Honda  of 
Japan  for  his  steel.  U.  S.  Patents  1,338,132, — 133,  and— 134,  but 
it  is  understood  that  the  invention  may  have  been  anticipated  by 
investigators  in  this  country. 


Wt)i^lijiS  EqnlpmDnt  In  tlm  Foim^lry 


W.  W.  REDDIE 

^lanager   Railway  Shop   Section, 
Westinghoiise  Electric  &  Mfg.  Company 

c  welding  apparatus  is  rapidly  be- 
essential  part  of  modern  foundry 
The  work  which  can  be  performed 
process  may  be  classified  into  three 


and  sink  heads,  from  steel 


ELECTRIC 
coming    an 
equipment, 
by  the  arc  weldin 
general  classes : — 

I — Cutting  of  heavy  riser 
or  iron  castings. 

2 — Repairing  castings,  such  as  the  filling  of  blow  holes 
or  building  up  parts  omitted   from  the  original  casting. 

3 — Repairing  foundry  equipment. 

Each  of  the  above  requires  different  treatment,  al- 
though the  same  type  of  welding  equipment  may  be 
used  for  all  classes  of  work. 

The  function  of  the  arc  welding  equipment  re- 
ferred to  in  this  article  is  to  supply  direct-current  hav- 
ing a  voltage  characteristic  suitable  for  welding.  The 
complete  equipment  includes  the  necessary  control, 
electrode  holders,  operator's  helmets  and  face  shields. 


equipment  of  the  port- 
This  machine  supplies 


A  single-operator  welding 
able  type  is  shown  in  Fig.   i. 

current  varying  from  50  to  225  amperes  for  metallic 
electrode  welding  and  150  amperes  maximum  for  car- 
bon electrode  welding.  If  several  of  these  machines 
are  available,  they  may  be  paralleled  to  obtain  higher 
current  values  for  both  welding  and  cutting. 

A  1000  ampere  welding  equipment  installed  in  a 
modern  foundry  is  shown  in  Fig.  2.  This  equipment, 
in  combination  with  the  proper  control  panels,  will 
supply  current  for  a  number  of  operators  working  in- 
dependently for  metallic  electrode  welding,  or  higher 
current  for  carbon  electrode  welding  or  cutting.  The 
range  of  current  adjustment  necessary  for  either  class 
of  work  may  be  obtained  from  the  same  control  panel. 
A  control  combination  frequently  used  for  multiple- 
operator  sets  is  shown  in  Fig.  3.     The  large  panel  on 


FIG.    I — SINGLE-OPERATOR    WEIJJING    EQUIPMENT 

Current  range  50  to  225  amperes. 

Motor-generator  sets  having  sufficient  capacity  to 
supply  current  for  carbon  electrode  work,  may  be  pro- 
vided with  control  panels  giving  current  regulation  for 
heavy  carbon  electrode  work,  or  for  metallic  electrode 
work.  The  high  current  capacity  sets  have  become 
known  as  multiple-operator  equipments,  because  they 
can  be  used  by  several  operators,  working  independently. 
Multiple-operator  equipments  are  built  in  capacities 
varying  from  300  to  1000  amperes.  Machines  having  a 
capacity  larger  than  1000  amperes  have  been  built,  but 
it  is  usually  found  that  the  1000  ampere  set  has  ample 
capacity  for  use  in  large  installations.  The  single-opera- 
tor unit  has  a  capacity  sufficient  for  one  welder  only, 
working  with  a  metallic  electrode,  over  a  range  of  from 
50  to  225  amperes. 


FIG.   2 — MULTIPLE-OPERATOR     WELDING     EQUIPMENT 

Current  capacity  1000  amperes. 

the  left  controls  the  generator  and  provides  for  current 
adjustment  from  250  to  750  amperes  for  carbon  elec- 
trode work.  The  small  panel  on  the  right  is  an  outlet 
panel  for  metallic  electrode  work.  One  or  more  of 
these  panels  can  be  used  with  the  multiple-operator  set. 
The  portable  outlet  panel,  Fig.  4,  is  also  frequently 
used  with  the  multiple  operator  equipment. 

The  single-operator  sets  are  designed  so  that  no 
power  is  dissipated  in  stabilizing  resistance  connected 
in  series  with  the  arc  circuit.  Such  a  set,  therefore, 
operates  at  a  much  higher  efficiency  than  the  multiple- 
operator  sets  which  require  a  stabilizing  resistance  in 
each  arc  circuit.  If  the  electrical  efficiency  was  the 
only  question  involved,  the  choice  of  type  of  equipment 
would  be  simple.     However  there  are  other  factors  that 


IMarch,  1921 


THE  ELECTRIC  JOURNAL 


97 


have  a  direct  bearing  on  the  choice  of  equipment 
namely : — 

I — llie  first  cost  01  the  welding  equipment. 

2 — The  cost  of  installation. 

3— The  ratio  of  carbon  electrode  jobs  to  metallic  elec- 
trode jobs. 

4 — The  floor  space  available. 

The  first  cost  of  a  number  of  single-operator  ma- 
chines will  be  considerably  more  than  the  cost  of  one 


0  (S 


The  ratio  of  carbon  electrode  work  to  metallic  elec- 
trode work  will  influence  the  choice  of  equipment  for, 
although  the  single-operator  units  may  be  operated  in 
parallel  to  obtain  high  currents>  the  ratio  of  jobs  may 
be  such  that  single-operator  units  will  not  be  available 
for  parallel  operation,  when  required.  Floor  space  may 
not  be  available  for  assembling  several  single-operator 
units  for  parallel  operation,  in  which  case,  one  multiple- 
operator  unit  must  be  used.  A  combination  of  the  two 
types  of  equipment,  in  many  cases,  makes  a  more  effi- 
cient and  flexible  installation. 


FIG.   5 — CUTTING    K, 


rEEL  C.\ST1NCS    WITH    THE 
.\RC 


FIG.    3 — GENERATOR   CONTROL   WITH   OUTLET   PANEL 

For   use  with  multiple-operator  equipment, 
multiple-operator  machine  for  the  same  total  capacity. 
The  distribution  cost  of  the  primary  source  of  current 
supply  will  usually  be  less  than  the  distribution  of  cur- 


;«,^:;;v\\^v 


Risers  and  sink  heads  are  cut  from  the  castings,  to 
best  advantage,  by  using  high  current  and  the  carbon 
arc,  but  repairs  to  castings  or  foundrj-  equipment  are 
usually  better  w-hen  made  with  the  metallic  electrode, 
using  current  values  varj'ing  from  150  to  200  amperes. 

Fig.  5  shows  a  heavy  job  of  cutting  with  the  car- 
bon electrode.  The  rate  of  cutting  depends  upon  the 
current  values  used,  and  it  is  good  practice  to  use  ap- 
proximately 500  to  650  amperes  maximum,  with  a  one 
inch  carbon  electrode.  With  this  current  about  five 
minutes  would  be  required  to  cut  through  a  steel  or  cast 


FIG.    6 — REPAIRS     MADE    TO    S  1  1  I 

METALLIC    EI-IXTKODE 


S    WITH    A 


FIG.   4 — PORTABLE    OUTLET    PANEL 

For  use  with  multiple-operator  equipment, 
rent  at. arc  welding  vojtage,  as  less  copper  will  be  re- 
quired. If  the  cost  of  power  is  high,  the  saving  in  op- 
erating.  expense  obtained  by  using  the  single-operator 
unit  may  off-set  the  higher  first  cost  of  the  single-opera- 
tor units. 


iron  block  four  in.  by  four  in.  Approximately  the  same 
length  of  time  would  be  required  to  cut  through  a  cir- 
cular cross-section  of  iron  of  five  in.  diameter.  Work 
of  this  nature  is  best  performed  by  means  of  high  cur- 
rent machines.  If  single-operator  machines  were  used, 
three  or  four  of  them,  operating  in  parallel,  would  be 
required,  each  machine  delivering  its  share  of  the  load 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


as    determined    by    the    setting   of    the    current-control     casting  and  the  deposited  material.     This  zone  of  hard 


rheostats. 

Castings  frequently  have  defects,  such  as  blow 
holes,  that  can  readily  be  repaired  by  means  of  the  elec- 
tric arc.     I'.liiw   holes  are  easily  filled  by  first  cleaning 


FIG.   7 — METAL   DEPOSITED   ON   CLOSE   GRAINED   C.^ST    IRON    WITH 
A   .METALLIC  ELECTRODE 

the  casting  thoroughly  and  then  filling  with  metal  de- 
posited by  the  metal  electrode.  If  the  defective  part  of 
the  casting  is  large,  the  cleaning  can  be  done  quickly  by 
melting  away  the  spongy  material  by  means  of  the  car- 
bon arc,  using  current  values  from  300  to  500  amperes, 
or  even  larger,  if  there  is  a  large  amount  of  defective 
metal  to  be  removed.  The  filling  of  small  blow  holes 
in  a  casting  with  the  metallic  electrode  is  shown  in 
Fig.  6. 

The   practice   of    repairing  just   described    applies 


FIG.   8 — METAL    DEPOSITED    OK    CAST    IRON 

With   either   a   large   diameter   metalHc   electrode   or   by   a 
carbon  electrode,  using  iron  filler  rods. 

principally  to  steel  castings.  The  welding  problems  en- 
countered in  cast  iron  work  are  more  complex.  It  is 
difficult  to  obtain  a  soft  weld  on  cast  iron,  due  to  the 
formation  of  a  layer  of  hard  metal,  apparently  a  high 
carbon  steel,  in  the  zone  of  fusion  between  the  parent 


metal  can  be  diffused  and  entirely  eliminated  by 
properly  annealing  the  casting.  Large  castings  of  gray 
cast  iron  are  usually  of  a  coarse  grain  structure  and  it 
is  difficult  to  obtain  good  fusion  between  the  casting  and 
the  deposited  metal.  Pre-heating  and  subsequent  an- 
nealing are  advisable  in  many  cases  in  order  to  obtain 
good  results  in  welding  cast  iron. 


FIG.   9 — METHOD   OF    STUDDING   CAST    IRON    TO   INCREASE 
STRENGTHS   OF   WELD 

Fig.  7  illustrates  the  method  of  building  up  a;  pad 
on  cast  iron  by  depositing  metal  by  the  metallic  elec- 
trode, and  the  filling  of  a  hole  which  was  later  drilled. 
The  hole  was  drilled  through  the  deposited  metal  only, 
so  that  the  hard  zone  referred  to  was  not  encountered. 
The  deposited  material  shown  in  section  could  easily  be 
machined  except  at  the  zone  of  fusion  between  the  de- 
posited metal  and  the  parent  casting. 

Filling  work  which  was  done  with  a  large  metallic 
electrode,  using  high  current  values,  is  shown  in  Fig.  8. 
The  section  at  the  four  inch  line  of  the  rule  was  filled 
with  %  in.   Nnrw.Tv  iron,  used  as  a  metallic  electrode. 


Sleel  PlateWeldiHi 
Similar  I0  iop. 

FIG.    10— REPAIRS  MADE  TO  THE  BODY  CASTING  OF 
ARC   AIR    COMPRESSOR 

The  slag  inclusions,  appearing  as  dark  spots  in  the  de- 
posit, are  to  be  expected  in  using  this  iron 
as  a  metallic  electrode.  The  section  under  the  13 
in.  mark  on  the  rule  was  filled  by  using  the  carbon  elec- 
trode and  the  same  grade  of  Norway  iron  as  a  filler  ma- 
terial.    Although  such  work  may  be  done  rapidly,  slag 


March,  1921 


THE   ELECTRIC  JOURNAL 


99 


inclusions  are  to  be  expected  when  the  average  opera-  surfaces  and  two  inches  thick  at  tlie  ribs.  The  total 
tor  deposits  the  iron  in  this  way.  The  slower  method,  length  of  the  weld  was  55  inches.  The  work  was  coni- 
using  a  smaller  metallic  electrode  will  result  in  a  de-  pleted  in  a  little  less  than  six  hours,  including  the  time 
posit  similar  to  that  shown  in  Fig.  7.  required  to  cut  and  prepare  the  steel  plate  (shown  in 

A  method  frequently  used  in  repairing  heavy  cast     the  illustration,)   to  do  the  welding,  and  to  set  up  and 
iron  castings  is  shown  in   Fig.  9.     The  metal   of   such     align   the   repaired   casting.     The  actual   welding  time 
castings  is  usually  coarse  grained  and  it  is  very  difficult     was  one  hour  and  25  minutes,  with  a  power  consump- 
tion of  12  kilowatt-hours. 

In  this  instance  the  result  was  not  only  a  saving  in 
the  cost  of  a  new  casting  but.  of  far  greater  import- 
ance, the  machine  was  in  service  again  within  a  short 
time,  whereas  several  months  would  have  lieen  neces- 
sary to  obtain  a  new  casting  and  do  the  necessary  ma- 
chining. 

The  general  statement  can  be  made  that  repairs  to 
foundry  products,  made  by  supplying  missing  parts,  or 
filling  blow  holes  in  steel  castings,  do  not  result  in  an 
inferior  product.  It  is  admitted  that  a  foundry  which 
was  too  percent  perfect  would  need  no  process  for  add- 
ing metal  to  castings  already  poured.  However  many 
discriminating  users  of  foundry  products,  after  tho- 
rough investigations  of  the  results  obtained  by  electric 
welding,  have  approved  its  use.  The  prejudice  which 
exists  to  a  certain  extent  against  "patclied  up"  castings 
will  disappear  as  knowledge  of  the  welding  processes 
and  the  results  which  are  obtained  through  their  use 
become  more  generallv  known. 


to  get  good  fusion  between  the  cast  iron  and  the  de- 
posited metal.  The  break  is  "V-ed"  out,  and  holes  are 
drilled  and  tapped  for  receiving  steel  studs.  The  cross- 
section  of  the  weld  shows  how  the  studs  act  as  anchors 
for  the  deposited  metal.  Some  interesting  and  valuable 
repair  work  has  been  done  by  using  this  method. 

Fig.  10  illustrates  the  successful  repair  of  a  broken 
casting  without  studding.  The  main  body  casting  of  a 
l;irg>.  compressor  was  broken  into  five  separate  pieces 
when  the  connecting  rod  of  the  compressor  became  dis- 
connected. The  parts  to  be  welded  formed  the  crank 
case,  which  had  to  be  oil  tight,  so  that  it  was  necessary 
to  make  a  weld  which  would  not  leak  oil  and  which 
would  be  sufficiently  strong  to  withstand  the  vibration 
of  the  compressor.  There  were  five  complete  fractures 
intersecting  each  other  at  five  points  within  a  radius  of 
eight  inches  so  that  in  making  this  weld,  careful  work- 
was  required  by  the  operator  in  order  to  avoid  trouble 
from  expansion  and  contraction  strains.  The  walls  of 
the  casting  were  approximately  one  inch  thick  on  flat 


:>a]  lloJay  Comiection^ '1(3 


LEWIS  A.   ItKVE.N 


WHERE  it  is  desirable  to  trip  oil  circuit 
breakers  from  the  current  transformers  con- 
nected on  the  main  line  without  the  interven- 
tion of  a  separate  source  of  tripping  current,  some  de- 
vice is  necessary  in  order  to  use  the  standard  overload 
relay  of  the  induction  type  with  its  desirable  features 
of  inverse  time  element.  The  use  of  this  direct  series 
trip  attachment  is  exemplified  in  Figs.  15  lo  20  inclu- 
sive, the  manner  of  operation  being  as  follows : — Refer- 
ring to  Fig.  15,  the  current  from  the  secondary  of  the 
current  transformer  passes  through  the  trip  coil  of  the 
oil  circuit  breaker,  through  the  primary  coil  of  the  di- 
rect trip  attachment,  and  finally  through  the  series  coil 
of  the  overload  relay.  When  the  current  exceeds  the 
trip  setting  of  the  overload  relay  and  the  contacts  of  the 
latter  close,  a  short-circuit  will  he  put  upon  the  second- 
ary of  the  direct  trip  attachment.  When-  the  short- 
circuit  is  established  in  the  secondary  of  this  small  auxi- 
liary transformer,  the  pull  exerted  by  the  main  coil  of 
the  direct  trip  attachment  will  be  quite  small,  thus  al- 
lowing the  pull  of  the  trip  coil  of  the  circuit  breaker  to 
take  effect,  causing  the  latter  to  operate. 

With  this  type  of  auxiliary  device,  the  current 
from  the  current  transformer  passes  through  the  trip 
coils  of  the  circuit  breaker  and  in  case  of  a  severe  short- 


circuit,  if  the  current  transformer  is  not  operating  near 
its  point  of  saturation,  the  current  flowing  in  the  trip 
coil  will  be  of  sufficient  magnitude  to  cause  the  circuit 
breaker  to  trip,  irrespective  of  the  condition  of  the  over- 
load relay.  In  order  to  avoid  such  a  contingency  an  in- 
ductive shunt  is  sometimes  used,  connected  in  parallel 


FIG.    15 — O.NE  TRIP  COIL  WITH  OVtKI.OAD  RELAY   AND  MRKCT 
TKIP  AlT.U'll.MK.ST 


with  the  trip  coil  of  the  breaker.  The  object  of  this 
shunt  is  to  divert  a  portion  of  the  current  from  the  trip 
coil  so  that  the  holding  coil  is  strengthened  at  the  ex- 
pense of  the  tripping  coil.  Under  these  circumstances 
the  holding  coil  will  fulfill  its  function  regardfess  of  the 
current  flowing  in  the  secondary  until  the  relay  contacts 
may  be  closed,  when  tripping  will  occur  according  to 
the  desired  relay  setting. 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


In  Fig.  15  a  single-phase  circuit  is  shown  with 
overload  relay  protection.  However,  reverse  power 
protection  can  be  secured  in  a  similar  manner,  render- 
ing it  unnecessary  to  have  a  separate  tripping  source  for 
circuit  breakers  provided  with  the  direct  trip  attach- 
ment. 

Figs.  16,  17  and  18  show  the  direct  trip  attachment 
as  used  with  three-phase  circuits,  giving  three  different 
connections  of  the  current  transformers,  while  Figs.  19 
and  20  show  three-phase  circuits  protected  by  three 
overload  relays  using  respectively  three  and  two  coils 
for  tripping.     As  a  rule  only  two  trip  coils,  two  relays. 


leaving  current,  as  shown  by  the  current  transformer, 
will  flow  through  the  differential  relay,  causing  it  to 
operate  and  trip  both  of  the  circuit  breakers,  thus 
isolating  the  apparatus  which  is  to  be  protected.  In 
this  connection  an  auxiliary  circuit  closing  multicontact 
relay  is  shown  which  operates  to  trip  both  of  the  cir- 
cuit breakers  without  having  their  trip  coils  connected 
in  parallel,  as  would  be  the  case  if  it  or  similar  means 
were  not  employed. 

In  order  to  avoid  the  cost  of  high-potential  cur- 
rent transformers,  the  scheme  of  connections  shown  in 
Fig.    22    may     be     used     for     overload     protection. 


fe 


FtG.    16 — TWO    TRIP    COILS    A.ND   TWO 

OVERLOAD    RELAYS     WITH    DIRECT 

TRIP    ATTACHMENT 


FIG.    17 — ONE    TRIP    COIL    AND    OVER- 
LOAD   RELAY    WITH    DIRECT    TRIP 
ATTACHMENT 


and  two  direct  trip  attachments  are  supplied,  while  with 
ungrounded  systems  two  current  transformers  con- 
nected in  V  are  considered  sufficient.  For  grounded 
systems  or  for  more  thorough  protection  of  the  un- 
grounded system,  three  current  transformers  may  be 
used  connected  in  Z. 

In  order  to  protect  electrical  apparatus  from  in- 
ternal defects  caused  by  grounds  or  short  circuits, 
relays  of  different  characteristics  may  be  used,  the 
function  being  to  balance  the  power  on  one  side  of  the 
apparatus  with  that  on  the  other  side.  Naturally  the 
amount   of   power   entering   will    correspond   with   the 


FIG.    19 — THREE    TRIPPING     COILS 

AND    THREE    OVERLOAD    RELAYS 

WITH     THREE    DIRECT    TRIP 

ATTACHMENTS 


FIG.   20 — TWO    TRIPPING    COILS 

AND    THREE    OVERLOAD    RELAYS 

WITH    TWO     DIRECT    TRIP 

ATTACHMENTS 


amount  leaving,  neglecting  the  small  internal  losses  of 
the  apparatus.  Fig.  21  shows  the  differential  relay 
scheme  arranged  to  protect  a  single-phase  transformer. 
As  long  as  no  internal  current  losses  occur  in  the 
power  transformers  the  current  in  the  secondaries  of 
the  two  current  transformers  will  simply  circulate  with- 
out any  of  it  passing  through  the  overload  type  of  relay 
which  is  connected  in  parallel  with  the  transformer  sec- 
ondaiy.  Should  a  loss  of  current  occur  in  the  power 
transformer,   the  difference  between   the  entering  and 


FIG.    18 — TWO    TRIP    COILS     AND    TWO 

OVERLOAD    RELAYS    WITH    DIRECT 

TRIP    ATTACHMENT 

The  z  connection  of  current 
transformers  is  used  with  a 
grounded  neutral  system 

The  only  high-tension  equipment  consists  of  a 
single  high-tension  bus  support  upon  which  is 
mounted  a  small  slate  panel  which  contains  the  low- 
tension  current  transformer  and  the  two  relays  shown 
in  the  diagram.  The  current  from  the  secondary  of 
the  current  transformer  passes  through  the  overload 
relays  and  through  two  coils  upon  the  transfer  relay. 
When  the  current  reaches  the  value  corresponding  to 
the  relay  setting  the  overload  relay  will  close  its  con- 
tacts, thereby  short-circuiting  a  shading  coil  which  will 
nullify  the  effect  of  the  lower  coil  of  the  transfer  relay 
and  cause  the  upper  coil  to  attract  the  plunger  of  the 


^J 


Multi    Contact 
Relay 


FIG.    21— DIFFERENTIAL    RELAY    ARRANGED    TO    PROTECT   TRANSFOR.MER 

transfer  relay,  pulling  with  it  a  micarta  chain.  The 
latter  serves  to  actuate  a  small  knife  switch  at  its  lower 
extremity  while  at  the  same  time  preserving  the  insula- 
tion of  the  high  potential  circuit  to  ground.  The  trip- 
ping circuit  is  connected  through  the  knife  switch  to  the 
circuit  breaker. 

The  same  type  of  transfer  relay  in  a  slightly  modi- 
fied form  is  shown  in  Fig.  24,  the  object  being  to  supply 
tripping  power  to  circuit  breakers  where  no  auxiliary 
supply  of  current  is  available.     As  in  the  case  of  Fig. 


March,  1921 


THE  ELECTRIC  JOURNAL 


22  the  current  from  the  current  transformers  normally 
circulates  through  the  overload  relay  and  through  the 
two  coils  in  the  transfer  relays.  These  two  coils,  being 
wound  on  separate  electro-magnets,  have  their  actions 
nmtually  opposed  upon  the  plunger  of  the  transfer  re- 
lay.    When  the  contacts  of  an  overload  relay  close,  they 


FIG.     22     HIGH-TENSIOX 

OVERLOAD    RELAY 

PANEL 


FIG.   23 — INTERNAL    CONNECT- 
IONS OF  REVERSE  POWER  RE- 
LAY     WITH      DOfBLE     TRIP 
CIKCUIT 


short  circuit  the  coil  wound  upon  the  lower  electro- 
magnet which  eliminates  the  pull  of  the  lower  coil  of 
the  transfer  relay,  which  is  connected  in  series  with  the 
overload  relay,  and  permits  the  plunger  of  the  transfer 
relay  to  be  drawn  up.  This  operates  the  small  switch 
within  the  relay,  whose  two  positions  are  clearly  indi- 
cated in  the  wiring  diagram.  In  normal  operation  the 
current  passes  from  the  current  transformer,  through 
the  overload  relay  to  b  and  c  in  the  switch  of  the  trans- 

ir 


FIG.   24 — CONNECTIONS     OF     AUXILIARY     RELAY     FOR     ALTERNATING- 
CURRENT   TRIPPING 

Connections    shown   are   as   viewed   from   the   rear   of   the 
apparatus. 

fer  relay,  through  the  two  coils  of  the  latter  and  back  to 
the  secondary  of  the  current  transformer  as  shown  at 
the  right.  After  the  overload  relay  has  caused  the 
transfer  relay  on  the  left  to  assume  the  tripping  posi- 
tion, the  current  from  the  current  transformer  will  pass 
through  the   overload   relay,   through   one   side  of   the 


switch,  then  from  a  to  1/  of  the  second  transfer 
relay,  and  though  the  trip  coil  of  the  circuit  breaker 
back  to  the  first  relay,  through  its  auxiliary  switch  and 
its  two  series  coils  to  the  other  side  of  the  current  trans- 
former. 

The  scheme  as  shown  can  be  used  for  reverse 
power  relays  and  the  same  combination  may  be  used 
in  a  general  way  as  is  shown  for  the  direct  trip  attach- 
ment for  oil  circuit  breakers  as  shown  in  Figs.  15  to  20. 
However,  more  positive  action  is  secured  with  connec- 
tions shown  in  Fig.  24  as  normally  no  current  flows 
through  the  trip  coil  of  the  circuit  breaker  and  there  is 
no  liability  of  tripping  the  breaker  under  short-circuit 
conditions  as  occurs  with  the  direct  trip  attachment 
where  current  from  the  current  transformer  always 
flows  through  the  trip  coil  of  the  circuit  breaker. 


Torque  Compensator. 


FIG.   25 — REraRSE  POWER   RELAY 

Internal  connections  viewed   from   rear  of   relay. 

Some  kinds  of  relays  depend  for  their  function 
upon  the  relative  directions  and  values  of  the  current 
and  the  voltage  in  the  electric  circuit,  such  as  reverse 
power  relays.  One  type  of  this  kind  of  relay  is  illus- 
trated in  Figs.  23  and  25.  The  relay  shown  consists 
of  two  elements;  the  first  being  a  standard  induction 
type  overload  relay  complete  with  contacts,  and  the 
second  consisting  of  current  and  voltage  coils  so  placed 
as  to  constitute  a  wattmeter  element.  The  second  ele- 
ment is  likewise  provided  with  relay  contacts  and  these 
close  whenever  the  direction  of  power  is  reversed  from 
the  direction  for  which  the  relay  is  set.  As  the  two 
sets  of  relay  contacts  are  connected  in  series,  no  trip 
circuit  will  be  established  unless  an  overload  is  present 
and  a  reversal  of  current,  occurs  at  the  same  time. 
Furthermore,  an  inverse  time  setting  is  provided  for  the 
overload  element,  so  that  surges  incident  to  switching 
or  synchronizing  will  not  trip  the  breakers  due  to  the 


THE  ELECTRIC  JOURNAL 


Vol.  X\III,  No.  3 


closing  of  the  relay  contacts.  An  additional  and  dis- 
tinct setting  is  made  for  the  amount  of  current  required 
to  operate  the  overload  element  as  may  be  seen  by  re- 
ferring to  Fig.  25,  current  taps  4,  5,  6,  7  and  8  am- 
peres. 

In  order  to  be  able  to  respond  to  very  low  torque, 
as  occurs  when  the  system  voltage  is  low,  the  relay  con- 
tacts are  quite  light,  and  for  that  reason  an  auxiliary 


or  contactor  switch  is  provided  inside  of  the  relay,  so 
that  the  current  for  tripping  purposes  will  pass  through 
the  main  contacts  of  the  contactor  switch,  the  latter  be- 
ing locked  in  by  its  own  current  until  the  breaker  trips. 
This  latter  feature  of  the  contactor  switch,  as  well  as  its 
design,  renders  an  auxiliary  or  pallet  switch  necessary 
at  the  circuit  breaker  in  order  to  interrupt  the  trip  cir- 
cuit. 


Soino  lyal)Oi'  ^Coiulltuyiis  M 


ir 


d>'^ 


Cx)3nT<:v 


OS 


W.  G.  McCONNON 

Service  Department 
.stingliouse  Electric  &  Mfg.  Company 


THE  increasing  interest  in  foreign  business  has 
brought  a  desire  for  all  information  possible  on 
the  conditions  of  labor  and  labor  costs  which 
diiier  from  those  in  the  United  States.  This  article 
will  be  confined  to  four  countries  where  the  writer  has 
had  extensive  experience;  namely,  Norway,  Japan, 
Mexico  and  Chile.  The  remarks  referring  to  Norway 
may  be  taken  in  a  general  way  as  applying  to  Denmark 
and  Sweden.  The  conditions  in  Japan  also  apply  in  a 
broad  general  way  in  China,  but  costs  in  China  are 
slightly  less  than  in  Japan.  Mexican  conditions  apply 
in  Central  America  also,  and  those  in  Chile  are  quite 
characteristic  of  South  America. 

The  labor  rates  as  given  apply  in  most  cases  to 
conditions  before  the  war.  My  work  in  Japan  was  in 
part  during  the  first  year  of  the  war,  but  prices  given 
are  prewar  prices.  In  South  America  the  work  was 
since  the  war.  The  great  probability,  we  may  assume 
is,  that  labor  costs  in  all  countries,  will  revert  to  ap- 
proximately prewar  values  in  a  very  few  years.  In  all 
these  countries,  however,  conditions  have  departed  less 
from  normal  than  in  the  United  States.  In  general  it 
may  be  assumed  for  all  foreign  work  that,  while  a  day's 
work  for  a  mechanic  or  a  day  laborer  costs  much  less 
per  day  than  in  the  United  States,  the  output  is  less  and 
in  every  way  the  efficiency  is  lower. 

NORWAY 

Of  the  labor  in  the  four  countries  mentioned,  that 
in  Norway  is  the  most  efficient,  and  most  nearly  corre- 
sponds to  our  own  labor  conditions.  In  191 2  I  was 
able  to  obtain  average  good  mechanics  in  Norway,  on 
work  of  erection,  at  from  six  to  eight  crowns  per  day 
of  nine  hours.  Common  labor  at  the  time  was  four  to 
five  crowns.  The  crown  at  normal  exchange  equals 
26.8  cents.     Station  operators  on  eight  hour  shifts  re- 


labor.  While  the  output  is  less  and  the  labor  is  slow 
the  work  is  usually  well  done  and  reliable.  1  found  the 
workmen  easy  to  get  along  with,  honest  and  capable  of 
taking  interest  in  the  work.  Methods  of  work  are 
rather  formal,  unnecessary  attention  being  given  to 
mere  details  which  are  not  vital  to  the  results  desired. 
As  Norway  is  considered  as  the  country  having  the 
greatest  of  all  water  power  output  per  unit  of  popula- 
tion and,  as  this  power  is  for  the  most  part  very  favor- 
ably located  and  is  being  rapidly  developed,  it  follows 
that  a  large  element  of  labor  is  being  educated  in  elec- 
trical work,  and  at  present  labor  conditions  are  quite 
favorable  for  those  called  upon  to  do  erection  work  in 
that  countty. 

JAP.\N 

To  the  engineer  who  is  lined  up  for  a  big  job  in  the 
Land  of  the  Rising  Sun,  the  imaginary  troubles  at  first 
thought  may  make  the  job  seem  rather  hopeless.  His 
troubles,  however,  will  be  along  rather  different  lines 
probably  than  those  that  first  occur  to  him.  It  probably 
is  best,  in  going  on  any  foreign  work,  not  to  form  any 
opinions  as  to  what  the  conditions  will  be,  or  what  we 
will  or  must  do.  Start  with  an  open  mind  and  espe- 
cially without  any  prejudices  for  or  against  what  you 
are  to  meet.  The  engineer  bound  for  Japan  will 
naturally  feel  he  will  be  much  handicapped  by  not 
knowing  the  language.  This  will  not  be  as  much  of  a 
detriment  to  him  as  a  failure  to  have  a  working  knowl- 
edge of  the  language  in  many  other  countries.  Many 
Japanese  engineers  have  had  training  in  England  or  in 
the  United  States  and  usually  know  our  language  well. 
Those  whose  training  has  taken  place  in  the  schools  of 
their  own  country,  usually  know  English  quite  well. 
While  they  naturally  talk  our  language  in  a  hesitating 
way,  and  chose  their  words  slowly,  they  almost  invari- 


ceived  130  to  150  crowns  or  say  $40  per  month.     Lady     ''W.v  use  good  English  and  express  themselves  correctly, 


stenographers  in  offices  in  Christiania,  who  could  take 
dictation  in  English,  German  or  Norwegian,  received 
100  crowns  or  $26.80  per  month.  In  output  of  work  per 
day,  I  would  consider  labor  as  ranking  about  75  percent 
in  comparison  with  labor  in  the  United  States.  This 
percentage  will  vary  somewhat  with  different  classes  of 


One  will  always  have  native  engineers  who  can  go 
into  matters  fully  and  can  translate  correctly  any  direc- 
tions given.  One  will  usually  be  taken  care  of  well  by 
the  concern  for  whom  the  work  is  being  done.  This, 
of  coilrse,  does  not  mean  one  will  have  food  or  sur- 
roundinsfs  entirelv  the  same  as  he  is  accustomed  to.  But 


March,    ujJi 


THE   ELECTRIC  JOURNAL 


103 


with  the  native  ways  of  service  and  native  customs, 
which  are  naturally  radically  different  from  our  own, 
one  will  be  well  provided  for.  At  the  Inawashiro  plant, 
where  the  writer  spent  most  of  1914  and  1915,  there 
were  four  foreign  engineers,  one  English,  two  German 
and  myself.  The  local  company  built  a  ten  room  house 
and  furnished  it  for  our  use.  Each  engineer  had  a  pri- 
vate room,  with  a  rest  room,  a  dining  room,  kitchen  and 
bath  room  and  two  living  rooms  for  a  Japanese  family 
to  cook  and  take  care  of  the  house.  This  family  had 
previously  been  in  the  service  of  an  American  family, 
;'nd  the  cooking  and  service  were  good. 

The  Japanese  mechanic  or  laborer  is  not  exactly  at 
home  in  handling  very  large  and  heavy  work.  This  is 
natural  from  his  limited  experience  on  this  class  of 
work.  However  in  handling  light  work,  and  especially 
such  work  as  can  be  done  without  cranes  or  tackle,  and 
with  only  the  most  primitive  tools,  he  is  rather  superior 
to  other  people.  This  refers  to  such  work  as  unloading, 
putting  in  place,  getting  things  ready  for  erection  and 
any  straight  ahead  work.  It  is  much  the  best  practice 
to  let  the  workmen  do  this  work  according  to  their  own 
particular  way,  so  long  as  this  is  possible.  One  of  the 
principal  difficulties  the  foreign  engineer  will  have 
with  Japanese  labor  is  getting  the  workman  to  do  cer- 
tain things  in  the  particular  way  wanted,  when  this  is 
necessary.  The  ordinary  Japanese  workman  usually 
decides  early  on  the  job  that  he  has  a  better  way  of 
doing  things  than  your  way.  Therefore,  for  work  that 
must  come  to  a  certain  fixed  standard  and  must  be  done 
in  a  certain  way,  it  will  be  necessary  to  show  the  worker 
exactly  how  this  should  be  done,  then  watch  the  work 
very  closely  and  allow  no  departure  from  the  methods 
shown.  The  workman  will  never  fail  in  his  ability  to 
imitate  exactly  what  you  do,  if  he  so  chooses,  but  he 
will  change  the  method  to  suit  himself  if  he  is  given 
any  opportunity  to  do  so.  No  worker  I  have  ever  met 
can  reproduce  a  piece  of  work  with  the  exactness  that 
a  Japanese  will  do  it,  if  necessary,  but  he  will  not  do  it 
your  way  if  he  can  possibly  avoid  doing  so. 

Labor  in  Japan  is  slow  and,  while  wages  are  low, 
the  item,  be  it  an  article  or  a  days  work,  costs  about  the 
same  as  in  the  United  States  in  the  end.  This  may  seem 
strange  or  unreasonable  to  many  considering  the  low 
labor  rates,  but  the  four  foreign  engineers  at  Inawashiro 
discussed  this  matter  many  times,  and  in  about  all  its 
phases,  and  we  came  invariably  to  the  conclusion  that 
the  other  nations  had  little  or  nothing  to  fear  from 
Japanese  labor,  when  the  cost  of  the  finished  product  is 
considered.  The  average  mechanic,  on  the  Inawashiro 
plant,  was  paid  about  one  yen  or  a  yen  ten  per  day. 
Some  specialists,  a  very  few,  received  one  and  one-half 
or  two  yen,  the  par  value  of  the  yen  being  49.8  cents 
or  say  fifty  cents.  Men  at  common  labor  received  about 
sixty  sen  or  thirty  cents,  the  sen  being  equal  to  one-half 
cent.  However,  more  than  half  of  the  common  labor 
about  the  construction  of  the  Tnawasliiro  powe'-  hnti^ie. 


c.  building  about  eighty  by  one  hundred  ami  m.mv  feet, 
by  seventy-tive  feet  high,  was  furnished  by  women  and 
girls  collected  from  the  small  villages  about  the  district. 
The  power  house  was  a  steel  frame  building,  filled  in 
with  brick  ;ind  cement.  Every  brick  and  hod  of  mortar 
or  sand  was  c.irried  up  on  this  building  by  women  and 
girls.  All  cleaning  of  machinery  and  polishing  of 
parts,  the  moving  of  freight  cars  and  similar  work  was 
done  by  women  and  girls,  and  all  fuel  and  provisions 
were  brought  in  on  iheir  backs.  For  this  labor  they  re- 
ceived an  average  of  thirty  sen  or  fifteen  cents  per  day. 
They  were  very  glad  to  receive  this,  as  it  was  nearly 
twice  as  much  as  could  be  earned  in  the  rice  fields 
which  represented  their  normal  employment,  and  was 
much  cleaner  work  and  more  healthful.  Station  oper- 
ators in  the  larger  and  better  plants  received  an  equiva- 
lent of  ten  to  fifteen  dollars  per  month,  and  in  some  of 
the  smaller  plants  as  low  as  five  dollars  per  month. 
Many  small  plants  are  in  charge  of  women  at  merely 
nominal  wages.  While  the  Japanese  will  not  resent  in- 
civility and  lack  of  formality  in  an  ecjual  degree  with 
the  Spanish  American,  formal  ways  and  methods  prob- 
ably count  for  more  in  the  actual  Japanese  life  than  in 
other  countries,  and  formal  methods  and  rather  extreme 
politeness  will  meet  with  much  consideration  from 
those,  one  is  doing  business  with.  A  considerable  de- 
gree of  firmness  in  a  duly  formal  and  polite  way  will 
probably  bring  the  best  results  on  most  occasions. 

MEXICO 

A  great  electrical  development  had  taken  place  in 
Mexico  and  was  being  carried  out  during  the  last  years 
of  Diaz,  as  President  of  the  Republic.  But  little  has 
been  done  since  and  many  of  the  larger  as  well  as  the 
smaller  plants  in  the  country  have  been  wrecked  and  put 
out  of  service  during  the  insurrection.  Having  been  in 
Mexico  during  Diaz'  time  and  again  in  1916,  the  con- 
trasted conditions  were  painfully  apparent  to  me.  As 
the  superintendent  of  the  big  Pearson,  no  000  volt 
plant  at  Orizaba  told  me  regarding  the  company's  simi- 
lar plant  at  Pueblo — "I  have  not  seen  it  for  two  years. 
It  has  been  out  of  service,  and  when  the  insurgents 
wanted  some  wire  or  a  shaft  or  pulley  or  other  item 
they  went  into  the  plant  and  took  what  they  wanted 
from  the  machines,  governors,  etc.  When  a  peon 
wanted  some  sole  leather  for  his  zapotos  he  went  in  and 
cut  it  out  of  a  belt." 

While  I  was  at  Orizaba,  the  employees  of  the  city 
railways  of  the  City  of  Mexico  went  on  strike.  While 
on  strike  the  government  drafted  these  men  and  sent 
them  to  the  training  camps  at  Orizaba.  They  brought 
with  them  all  the  controller  handles  and  many  of  the 
motor  brushholders  and  destroyed  these  parts  at 
Orizaba.  Such  impulsive  and  irresponsible  acts  are 
rather  characteristic  of  organized  labor  in  Mexico,  and 
are  liable  to  make  conditions  uncertain  and  expensive. 
It  is  a  relatively  common  thing  to  leave  work  at  night 
with  apparently  the  happiest  of  understanding  existing, 


I04 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


and  have  a  strike  before  work  starts  in  the  morning. 
The  interminable  "fiesta"  or  holiday,  can  usually  be 
reckoned  on  as  due  once  or  twice  a  week.  This,  how- 
ever, is  not  so  bad,  as  you  know  it  is  due  as  a  custom  of 
the  country. 

As  i;i  all  Spanish  speaking  countries  it  is  not  advis- 
able for  an  engineer  personally  to  do  any  more  real 
physical  work  about  his  plant  than  may  be  absolutely 
necessary.  If  he  does  he  will  lose  caste  with  both  the 
management  and  labor  itself.  A  man  in  Mexico  will 
work  to  very  much  greater  advantage  if  he  has  a  slight 
knowledge  of  the  language,  and  even  for  one  going 
down  there  for  a  single  trip,  it  would  be  well  to  pur- 
chase a  book  or  dictionary  giving  common  words  and 
expressions.  It  will  not  be  found  difficult  to  pick  up 
enough  of  the  language  to  make  life  go  smoother  and 
help  things  along  very  much.  Common  labor  was  at  a 
rate  of  fifty  to  seventy  cents  per  day  and  mechanics 
about  twice  that  rate.  An  engineer  in  charge  of  erec- 
tion will  find  he  must  watch  the  work  closely  as  it  goes 
along,  on  account  of  tlie  most  unexpected  things  being 
done  by  the  workman.  Patience  will  be  a  necessary 
virtue.  Politeness  and  consideration  will  take  one  far 
in  all  Spanish  speaking  countries. 


Somewhat  similar  methods  as  to  labor  and  working 
conditions  exist  in  all  the  Latin  American  countries,  but 
I  think  labor  in  general  will  be  found  more  intelligent 
and  better  in  an  all  around  way  in  Chile  than  in  Mexico. 
The  Chileno  has  been  spoken  of  as  the  Yankee  of  South 
America.  While  the  comparison  thus  implied  may  not 
be  very  apparent,  still  there  are  some  reasons  for  the 
expression.  W^ages  vary  greatly  throughout  the  coun- 
tiy.  While  agricultural  labor  probably  represents  the 
greatest  labor  element,  mining  and  the  nitrate  interests 
are  big  employers  of  common  labor.  Wages  may  vary 
from  a  peso,  usually  about  20  cents,  per  day  on  the  big 
estates  to  as  much  as  six  or  eight  pesos  for  similar  un- 
skilled labor  at  the  mines.  Some  mechanics  of  the 
better  class  at  the  mines  get  as  much  as  twelve  to  fifteen 
pesos  per  day.  In  connection  with  the  above  rates  it 
should  be  noted  that  the  agricultural  laborer  has  hi.«  liv- 
ing practically  free,  while  the  mine  worker  has  not.  At 
the  more  important  mines  virtually  all  superintendents, 
foremen  and  head  operators  are  American  or  English. 
On  work  consisting  of  rebuilding  a  number  of  large 
transformers  for  one  of  the  mining  companies,  the 
writer  paid  his  labor  six  to  eight  pesos  per  day  of  nine 
hours.  These  men  were  rather  above  the  average  in  in- 
telligence and  reliability.  The  Chileno  laborer  is  less 
impulsive  than  the  Mexican  and  has  relatively  few  holi- 
days to  keep  him  from  his  work.  His  standard  of  liv- 
ing is  higher,  and  in  all  wa}'S  he  is  more  dependable. 
The  same  necessity  will  exist,  however,  in  South 
America  as  in  Mexico,  for  the  engineer  to  watch  closelv 


the  work  as  it  goes  on,  largely  because  this  class  of  work 
is  entirely  different  from  what  the  natives  are  used  to, 
and  equally  due,  perhaps,  to  a  natural  irresponsibility  in 
the  native  character.  The  engineer  must  hold  himself 
responsible  for  all  work,  much  more  than  in  the 
United  States.  On  a  day  rate  no  effort  will  be  made  to 
hurry  work.  As  they  say  in  the  country,  there  is  no 
word  or  expression  in  Chileno  Spanish  for  hurry.  , 
However,  the  native  will  work  hard  and  faithfully  on 
piece  work,  if  given  rates  that  will  bring  him  in  a  little 
better  daily  return.  I  have  increased  output  fifty  per- 
cent by  giving  a  rate  on  piece  work  that  enabled  the 
operator  to  make  eight  pesos  per  day  in  place  of  si.x  or 
seven. 

While  labor,  in  the  class  of  work  an  electrical  en- 
gineer wants  done,  is  not  efficient  from  our  point  of 
view  in  most  of  these  countries,  still  one  must  consider 
matters  from  an  entirely  di'fferent  view  point  than  in 
the  United  States.  This  is  particularly  true  in  the 
Spanish  speaking  countries,  and  I  think  most  right 
minded  men  will  come  to  feel  a  sympathy  for  and  an 
appreciation  of  some  of  the  good  qualities  found  in  the 
poor  peon  or  roto  of  the  southern  countries.  He  is 
ignorant  and  lacks  energy  and  initiative,  but  the  work 
we  put  up  to  him  is  so  entirely  different  from  anything 
his  previous  life  has  shown  him  that  he  cannot  be  ex- 
pected to  adapt  himself  quickly  to  new  conditions. 
Owing  to  the  class  feeling  in  these  countries  he  has  al- 
ways been  looked  down  upon  and  treated  as  a  depend- 
ent and  an  inferior.  My  own  experience  has  been  that 
some  little  consideration  for  these  men,  and  an  appre- 
ciation of  their  efforts,  has  had  a  remarkable  resultant 
effect  on  their  work  and  faithfulness. 

In  the  United  States,  we  are  a  rather  brusque  and 
direct  acting  people.  While  we  perhaps  take  a  very 
just  pride  in  our  ability  to  accomplish  results,  and  in 
our  ways  of  doing  so  at  home,  in  going  to  foreign  coun- 
tries we  sometimes  fail  to  appreciate  the  fact  that  long 
experience  and  well  established  customs  in  these  coun- 
tries cannot  be  changed,  and  our  own  methods  of  doing 
things  are  not  best  away  from  home.  It  is  not  advis- 
able to  try  to  drive  matters  in  the  Spanish  speaking 
countries,  but  rather  to  keep  in  line  with  established 
methods.  Formality  and  extreme  politeness  are  uni- 
versal and  must  be  observed.  Even  in  dealing  with 
common  labor,  politeness  and  consideration  will  take 
one  very  far.  You  will  seldom  find  a  workman  or 
laborer  who  will  not  meet  your  efforts  in  this  direction 
with  an  equal  return,  and  they  very  much  appreciate 
any  sincere  consideration  on  your  part  of  their  work. 
Don't  be  familiar  but  be  sincere,  considerate  and  polite. 
This  may  seem  a  common-place,  but  a  real  showing  of 
these  qualities  counts  for  much  more  in  these  countries 
than  with  us.  We  want  to  live  down  the  name  of 
"Calibans"  or  "savages",  which  is  frequently  applied  to 
us.  and  which  has,  to  a  considerable  extent,  been  justi- 
fied bv  the  actions  of  some  of  our  countrymen. 


March,   iQ-'i 


THE  ELECTRIC  JOURNAL 


105 


©FIEP'^'ir^^^f^    Data 
FOR  com.                               -.ATEOl^S 

THE 
ELECTRIC 
JOURNAL 

MARCH 
H21 

Commutator  Maintenance  of  Synchronous  Converters 


The  creditable  performance  of  a  large  synchronous  con- 
verter is  as  much  dependent  upon  the  condition  of  the  commvi- 
tator  as  upon  any  other  one  item.  It  should  also  be  borne  in 
mind  that  a  commutator  only  becomes  thoroughly  "seasoned", 
(the  insulation  baked  out  and  all  parts  in  their  final  set  posi- 
tion) after  operating  in  service  for  a  considerable  time,  fol- 
lowed by  some  tightening  and  grinding.  Owing  to  lack  of  facil- 
ities for  heavy  current  loading  at  the  works,  it  is  not  feasible, 
in  all  cases,  to  completely  season  large  commutators  before 
shipment.  It  should  be  expected,  therefore,  that  a  certain 
amount  of  tightening  and  grinding  will  need  to  be  done  after 
the  converter  is  put  in  service,  particularly  if  the  commutator  is 
of  large  size.  The  importance  of  having  the  maintenance  and 
repair  work  on  commutators  done  always  under  the  direct 
supervision  of  experienced  mechanics  should  not  be  overlooked. 


I-IC.    I — GRINDING    DEVICE    FOR    TRUING    COMMUT.VTORS 

The  indication  that  the  commutator  needs  attention  will 
usually  be  manifested  by  a  general  uncvcnncss  or  roughness 
caused  by  high  or  low  bars.  It  is  seldom  that  trouble  is  occas- 
ioned by  flat  spots  or  eccentricity.  However,  if  these  condi- 
tions are  not  corrected  in  the  early  days  of  their  development, 
poor  commutation  is  inevitable,  causing  overheating  of  the 
commutators  and  rapid  deterioration  of  the  brushes,  clips  and 
pigtails ;  and  the  ability  of  the  machine  to  handle  overloads  will 
be  greatly  impaired. 

.  In  exceptionally  bad  cases,  where  flat  spots  exist,  or  there 
is  eccentricity,  it  may  be  necessary  to  use  a  turning  tool,  but 
for  ordinary  cases  a  grinding  tool.  Fig.  i,  is  preferable  and  is 
recommended.  Commutators  should  always  be  ground  at  full 
normal  speed.  In  cases  where  converters  are  motor  started, 
the  starting  motor  can  readily  be  utilized  for  grinding.  Care 
should  be  taken,  however,  to  see  that  starting  iiiotor  windings 
do  not  overheat,  as  starting  motors  are  only  designed  for  short 
time  service  and  their  continued  operation,  for  commutator 
grinding,  must  be  with  caution  in  this  rcspt-ct. 


FIG.   2 — SECTION     OF    CO.\IMUT.\TOk    SHOWING    AUXILIARY    V-RING 

On  self-starting  converters,  a  shaft  extension  is  provided 
on  the  alternating-current  end  for  mounting  a  pulley  to  drive 
the  rotor  for  grinding,  and  where  possible  to  do  so,  it  is  pre- 
ferable to  grind  by  this  procedure.  Where  it  is  not  feasible  to 
mount  a  pulley  for  separate  drive  grinding,  the  rotor  can  be 
driven  at  synchronous  speed  from  the  starting  taps  on  the 
transformer,  if  it  is  an  alternating-current  self-started  unit,  or 
on  reduced  direct-current  voltage,  if  it  be  a  direct-current 
started  unit.  Great  care  is,  of  course,  necessary  in  grinding, 
when   running  a  converter   under   its   own   power,   due  to  the 


voltage  between  comnmialur  bars.  The  undcsirability  of  hav- 
ing to  leave  some  of  the  direct-current  brushes  down,  when 
grinding  by  running  from  the  direct-current  side,  is  obvious. 
In  cases  where  grinding  is  done  by  driving  from  the  direct- 
current  side,  just  as  few  brushes  as  possible  should  be  left 
down  for  carrying  current  into  the  armature.  Ordinarily,  half 
of  the  brushes  on  two  adjacent  arms  arc  sufficient.  This  per- 
mits grinding  half  of  the  face  of  the  commutator  at  a  time. 
leaving  the  brushes  down  only  on  that  part  of  the  commutator 
where  the  stone  is  not  working.  All  brushes  used,  however, 
while  grinding  is  being  done  in  this  manner,  should  be  thor- 
oughly cleaned  off  before  the  machine  is  again  put  back  in  serv- 
ice, as  some  copper  and  stone  dust  is  sure  to  become  imbedded 
in  the  face  of  the  brushes.  This  will  not  only  cause  rapid 
wear  of  the  brushes  themselves,  if  it  is  not  cleaned  out,  but  will 
also  scratch  and  otherwise  damage  the  commutator  and  impair 
commutation.  In  grinding  the  commutator  when  running 
from  the  direct-current  side,  it  is  well  to  provide  some  sort  01 
an  insulated  platform  for  the  operator.  In  case  it  is  found 
necessary  to  mount  the  grinding  tool  on  the  positive  arm  of  a 
machine  having  the  negative  grounded,  it  is  also  desirable  to 
arrange  for  insulating  the  tool,  as  an  extra  precaution  for  pro- 
tection to  the  operator.  The  danger  of  dragging  copper  across 
bars  and  short-circuiting  them  should  also  be  given  consider 
ation,  when  grinding  is  being  done  by  driving  from  the  dir^  it 
current  side  with  appreciable  voltages  existing  across  a<l;.atiit 
bars. 


FIG.    3 — SECTION    OF    COM.MUTATOR    SHOWING    V-RINGS 

Turning  a  commutator  requires  a  much  lower  speed  than 
for  grinding.  The  speed  for  turning  should  not  exceed  150  ft. 
per  minute. 

Before  grinding  a  commutator,  the  machine  should  have 
been  in  service  a  sufficient  length  of  time  to  bring  the  temper- 
ature of  the  commutator  up  to  a  constant  value  of  at  least  100 
degrees  C.  The  machine  should  then  be  shut  down  and  the 
bolts  holding  the  commutator  V  ring,  shown  in  Fig.  2.,  should 
be  tightened.  This  process  of  heating  and  tightening  should 
be  repeated  until  the  commutator  bolts  cannot  be  tightened 
further,  using  a  wrench  that  will  not  stretch  the  bolts.  The 
proper  leverage  for  use  on  commutators  to  insure  tightness 
and  still  not  injure  the  bolts  is  approximately  as  follows,  as- 
suming an  average  man  (140  lbs.  pull)  at  the  end  of  the 
wrench : — 


Inches  Diam.  of  Bolts 

Inches  Wrench  Length  to  L"sc 

I 

I-J4 

i-i 

12 

24 
36 
60 

*This  is  a  companion  article  to  the  one  by  the  author  on 
"Commutator   Brushes",   in   the   Journal    for   Feb.   31,   p.    S'- 


In  tightening  commutators  having  the  double  V  construc- 
tion, shown  in  Fig.  },  the  outside  or  auxiliary  V  bolts  should 
always  be  backed  off  slightly,  s.ay  one-half  turn,  before  attempt- 
ing to  tighten  the  holts  of  the  main  V.  After  the  machine  is 
given  its  linal  tightening,  it  should  be  run  for  at  least  12  hours 
to  reach  a  constant  temperature  on  the  commutator  of  at  least 
100  degrees  C  before  grinding.  The  commutator  should  then 
be  ground  down  to  a  true  surface. 


io6 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  3 


It  may  be  found,  after  finishing  the  grinding,  that  the  un- 
dercutting has  been  so  ground  away  as  to  leave  sharp  edges  or 
burrs  along  the  slotting.  These  sharp  edges  should  always  be 
bevelled  off,  and  the  undercutting  thoroughly  cleaned  out  be- 
fore putting  the  machine  in  service  again.  To  clean  out  the 
undercutting,  any  small  stiff-bristled  brush  may  be  used.  .A 
brush  with  soft  iron  wire  bristles  will  be  found  good  for  this 
purpose.  In  extreme  cases  the  undercutting  may  have  been 
entirely  removed  by  the  grinding,  so  as  to  leave  spots  where  the 
mica  will  be  flush  with  the  copper.  In  such  cases,  the  mica 
should  be  re-undercut  to  a  depth  of  about  1/16  inch,  and  the 
edges  bevelled  and  the  slots  cleaned  out.  The  occasional 
brushing  out  of  the  commutator  undercutting  will  be  found 
very  effective  in  maintaining  good  commutation,  as  well  as  pro- 
longing the  life  of  the  brushes.  The  deposit  in  the  slots  from 
any  graphite  grade  of  brush  always  causes  slight  sparking,  as 
well  as  some  arcing  and  pitting  on  the  brush  face.  These  fac- 
tors mean  burning  along  the  edge  of  the  commutator  bars, 
accompanied  by  e.xtra  rapid  wear  of  the  brushes. 

In  finishing  off  a  commutator,  emery  cloth  or  paper  should 
never  be  used  on  account  of  the  continued  abrasive  action  of 
the   emerv   which   becomes   imbedded   in   the   copper   bars   and 


brushes.  Even  when  using  sandpaper  on  a  connnutator,  the 
brushes  should  always  be  raised,  and  the  connnutator  wiped 
clean  with  a  piece  of  canvas  lubricated  with  a  very  small 
quantity  of  vaseline  or  oil.  Cotton  waste  should  never  be  used, 
and  an  excess  of  any  kind  of  lubricant  should  always  be 
avoided. 

The  armature  winding  should  also  be  thorouglily  protected 
during  the  time  of  grinding  a  commutator,  to  prevent  accumu- 
lation of  dirt  and  metal  chips  back  under  the  commu- 
tator necks,  which  may  result  in  an  insulation  failure  when  the 
machine  is  again  put  in  service.  This  protection  can  usually 
be  obtained  by  using  a  circular  shield  of  fullerboard,  or 
similar  material,  around  the  commutator  at  the  end  next  to  the 
armature,  as  shown  in  Fig.  i.  This  shield  can  easily  be  sup- 
ported from  the  brushholders  arms  and  should  extend  from  the 
commutator  surface  to  an  inch  or  two  above  the  surface  of  the 
armature.  In  turning  off  a  commutator,  it  is  always  desirable 
to  put  a  temporary  canvas  hood   over   the  armature  winding. 

-After  grinding,  the  complete  machine  should  be  thoroughly 
cleaned  by  blowing  out  w'ith  dry  compressed  air,  before  re- 
placing it  in  service. 

R.  H.  Xewton 


JjlOUjTui^A 


Li^ 


JESTIQN   BQ'X 


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means  of  securing  authentic  information  on  electrical  and 
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materials  desired  for  particular  neids  will  be  answered. 
Specific  data  regarding  design  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


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velope should  accompany  each  query.  All  data  necessary  for 
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expecting  a  reply. 


1975  —  Chordeu  Wixdixi.s  —  In  Mr. 
Dudley's  article  of  February,  1916, 
the  following  statement  is  made:  'Tt 
is  customary  to  wind  the  coil  in  slots 
so  that  it  spans  something  less  than 
full  pole  pitch."  I  would  like  to  know 
why  this  is  as  it  seems  to  me  a  unity 
value  chord  factor  would  be  the  most 
efficient.  c.w.s.   (c.\l.") 

It  often  happens  that  the  number  of 

series  turns  necessary  for  a  given  volt- 
age of  an  induction  motor  is  not  de- 
sirable froiu  the  standpoint  of  the  best 
arrangement  of  the  conductors  in  the 
slot.  In  such  a  case,  a  larger  number 
than  actually  required,  but  which  gives 
the  best  arrangement  of  the  conductors 
in  the  slot,  is  selected  and  the  effective 
number  of  turns  may  be  decreased  to 
that  required  by  the  proper  chording  of 
the  winding.  The  effective  number  of 
turns  equals  the  actual  iiumber  of  turns 
times  the  sine  of  half  of  the  number 
of  electrical  degrees  spanned  by  the  coil. 
The  fact  just  mentioned  makes  the 
short  pitch  winding  very  convenient 
froiTi  the  design  standpoint.  Short 
pitch  windings  increase  very  consider- 
ably the  percent  of  thv.  total  length  of 
the  coil  which  is  imbedded  in  the  iron. 
This  reduces  the  heating  of  the  wind- 
ings because  the  iron  will  conduct  the 
heat  away  from  the  coils  more  readily 
than  the  surrounding  air.  Incidentally 
this  type  of  winding  results  in  a  sav- 
ing of  copper  and  insulation.  A  sinu- 
soidal wave  form  is  the  ideal  for  an 
induction  motor.  This  can  be  obtained 
only  appro-ximately  in  practice,  but  de- 
creasing the  pitch  shifts  the  layers  of 
the  windings  through  a  certain  angle 
from  the  full  pitch  position.  Thus  an 
overlapping  of  the  current  of  the  differ- 
ent phases  is  obtained  which  improves 
the  flux  distribution.  e.e. 


1976 — Choke  Coil — In  connection  with 
the  type  S  lightning  arresters  on  lines 
caro'ing  up  to  50  or  60  amperes,  2300 
volts,  we  have  been  using  home  made 
choke  coils,  consisting  of  about  30 
turns  of  No.  4  hard  drawn  weather- 
proof copper  wire  wound  on  a  two 
inch  pipe  as  a  mandril.  When  sus- 
pended the  coils  arc  stretched  to  se- 
cure a  small  air-gap  between  the 
turns.  Will  you  kindlv  critcise  the 
practice. 

A.T.T.  ( alberta") 
Our  criticism  is  that  a  coil  with  such 
a  small  diameter  has  almost  a  negligi- 
ble inductance.  It  is  a  step  in  the  right 
direction  though.  The  inductance  of  a 
coil  increases  as  the  square  of  the  di- 
ameter. G.C.D. 

197-  —  Damping  Windings— Will  you 
please  explain  how  the  size  of  copper 
and  its  most  efficient  location  is  de- 
termined for  putting  in  an  amortiser 
winding  on  an  alternator?  Will  you 
give  an  example  showing  how  it 
would  work  out  in  a  particular  case' 
c.w.H.    (n.   j.) 

The  purpose  of  an  amortissucr  wind- 
ing in  a  polyphase  alternator  is  to  damp 
out  pulsations  in  angular  velocity  which 
arise  from  irregularities  in  the  driving 
torque.  Voltage  is  generated  in  the 
damper  winding  proportional  to  the 
amount  of  pulsation  in  velocity  at  which 
it  occurs.  With  a  given  voltage  the 
current  and  consequently  the  damping 
torque,  depends  upon  the  impedance  of 
the  damper  winding.  Since  it  is  desir- 
able to  reduce  the  pulsations  in  velocity 
to  a  minimum  the  damper  winding 
should  have  as  low  an  impedance  as 
possible.  This  means  that  a  relatively 
large    number    of    bars    of    large    cross 

section     should     be     used.    Since     the 


amount  of  pulsation  in  driving  torque 
is  a  rather  uncertain  quantity  to  predict, 
and  since  the  allowable  variation  in  ve- 
locity is  usually  indefinite,  the  number 
and  size  of  damper  bars  cannot  be  cal- 
culated with  the  same  degree  of  accu- 
racy as  most  of  the  other  parts  of  the 
machine.  Generators  which  are  to  bo 
driven  by  gas  engines  or  other  prime 
movers  having  large  torque  variations 
require  heavier  dampers  than  those 
driven  by  prime  movers  with  more 
nearly  uniform  torque,  but  in  any  case 
the  actual  design  is  based  more  upon 
judgment  and  experience  with  other 
machines  than  upon  definite  calculations. 
One  general  rule  which  applies  to  the 
spacing  of  the  bars  is  that  the  distance 
between  them  should  not  be  equal  to  the 
armature  tooth  pitch  or  any  multiple  of 
the  stator  tooth  pitch.  Usually  a  differ- 
ence of  15  to  20  per  cent  between  the 
rotor  and  stator  tooth  pitches  is  main- 
tained. If  the  spacing  of  the  damper 
bars  coincides  with  the  stator  slot  spac- 
ing, the  generator  may  be  unsatisfac- 
tory due  to  noise,  increased  losses  or  a 
poor  wave  form.  QG. 

1978 — Meter  Connections  for  Three- 
Phase  Circuits— Where  instruments 
are  connected  through  current  trans- 
formers on  a  three-phase  system. 
what  is  the  advantage  in  using  a  cur- 
rent transformer  in  each  phase.  T 
have  been  told  this  is  to  take  care  of 
unbalanced  loads  but  1  cannot  see 
why  two  transformers  will  not  do 
the  same.  r.h  l.    (b.  c.) 

The  third  current  transformer  on  a 
three-phase.  three-wire  system  is 
only  of  advantage  to  help  to  carry  the 
secondary  instrument  load;  if  only  two 
transformers  were  used  they  might  be 
overloaded.  In  a  three-phase,  four- 
wire  system  it  is  necessary  to  use  three 


J 


March,  1921 


THE   ELECTRIC  JOURNAL 


107 


current  transformers  in  order  to  mea- 
sure the  currents  wnfcli  might  tlow 
from  any  line  to  neutral  or  ground. 
The  third  transformer  does  not  influ- 
ence the  effects  of  unbalanced  loads  on 
three-phase,  three-wire  circuits,  which 
are  properly  metered  with  two  current 
transformers.  The  connections  cm- 
ployed  for  measuring  various  loads 
under  all  possible  conditions  in  alter- 
nating current  circuits  have  been  thor- 
oughly discussed  by  Mr.  Group  in  a 
series  of  articles  on  '"Switchboard 
Meter  Connections  for  Alternating- 
Current  Circuits"  published  in  the  Jour- 
nal for  January  to  July  IQ20.  The  ar- 
ticle describing  in  detail  the  connections 
for  measuring  any  load  under  all  pos- 
sible conditions  in  a  thiec-phase,  three- 
wire  circuit  was  published  in  the  March 
issue.  p.M.c. 

1979   —    Lo\V-VoLT.\GE        DlRECT-ClrRRENT 

Generators — A  10  pole  shunt  wound 
commutating  pole,  75-12.S  volts,  3600 
ampere  direct-current  generator  was 
connected  to  an  electrolytic  load  con- 
sisting of  a  number  of  tanks  in  ser- 
ies. On  a  certain  occasion  a  number 
of  tanks  were  cut  out  and  it  should 
have  only  required  about  20  volts  to 
circulate  the  3600  amperes.  The  above 
machine  field  rheostat  was  set  for 
20  volts  and  the  machine  connected 
across  the  tanks.  Immediately  the 
voltmeter  and  ammeter  went  over  to 
full  scale  and  the  machine  circuit 
breaker  tripped  out,  it  being  set  for 
4500  amperes.  Do  you  suppose  that 
it  was  possible  that  the  machine  built 
up  as  a  series  generator,  the  commu- 
tating poles  acting  as  a  series  field,  in 
other  words  compounding,  there  be- 
ing just  enough  shunt  field  to  allow 
the  machine  to  build  up,  after  which 
the  commutating  pole  overcame  the 
shunt  field.  I  am  of  the  belief  that 
the  above  machine  when  operated  on 
the  very  low  voltages  would  operate 
much  better  if  the  commutating  poles 
were  not  energized.  I  would,  there- 
fore, propose  short-circuiting  them. 

R.H.L.  (n  c  ■) 
It  is,  of  course,  possible  that  the 
brushes  are  so  set  that  the  commutating 
pole  flux  is  serving  as  useful  flux  for 
generating  voltage.  This  would  be  due 
to  the  setting  of  the  brushes.  Moving 
the  brush  forward  would  decrease  the 
voltage  and  moving  the  brushes  back- 
ward would  increase  the  voltage.  The 
commutating  poles  should  be  energized 
at  low  voltage  as  w-ell  as  high  voltage. 
The  remedy  for  the  above  trouble  is  to 
move  the  brushes  forward  a  slight 
amount  so  as  to  avoid  the  compounding 
effect  due  to  the  commutating  pole  flux. 
n.H. 

1980 — Delta  Connected  Transformers 
— The  high  tension  windings  of  three 
200  kw.  single-phase,  60  cycle,  trans- 
formers are  connected  in  delta  for 
13  200  volts,  three-phase,  and  the  low- 
tension  windings  are  connected  in 
delta,  feeding  a  440  volt,  three-phase 
_  circuit,  and  a  tap  is  taken  from  the 
center  of  the  low  tension  winding 
from  each  transformer  as  shown  in 
Fig.  (a),  for  a  220  volt  ,  three-phase 
feeder.  Both  the  440  volt,  and  the 
220  volt  three-phase  feeders,  supply 
power  for  motors  in  the  same  plant, 
about  70  percent  of  the  load  being  on 
the  440  volt  feeder  and  about  30  per- 
cent on  the  220  volt  feeder.  This 
system  will  operate  satisfactorily 
when   both   sets   of    feeders   are    free. 


However,  industrial  plant  distribution 
systems  are  very  rarely,  if  ever,   free 
from  grounds.     In  Fig.  (a).  A,  B  and 
('   represent   the   three  440   volt   legs, 
while  A',  B'  and  C  represent  the  220 
volt  legs,  assuming  leg  C"  on  the  440 
volt  system  to  be  grounded,  tlicu  what 
will  be  the  potential   from  A'  on   the 
220    volt    system    to    ground?     Please 
show   in  detail  the  method   for  deter- 
mining   what  the  maximum  voltage  will 
be  from  some  leg  on  the  220  volt  .sys- 
tem   to    ground    with    conditions,    as 
above  stated.     Is  it  not  a  fact  that  the 
220  volt  motors  and  apparatus  will  be 
subject  to  a  strain  of  over  100  percent 
of  normal  voltage  to  ground,  when  a 
ground  occurs  on  the  440  volt  system. 
w.  s.  D.   (tenn.) 
Referring  to  Fig.  (a),  by  drawing  the 
equilateral  triangle  representing  the  vol- 
tage to  some  suitable  scale,  the  voltage 
between      any      two      points       can      be 
measured  off.     For  instance,  the  poten- 
tial between  C  and  A'  is  the  altitude  of 
an   equilateral   triangle   whose   sides  are 
440  volts,  its  value  is  ]-    (440)"  —  (220)" 
^  381  volts.     When  C  is  grounded.  A' 
is   3S1    volts   above   ground.     This   con- 
nection   is     not    desirable    because    the 


KiGS.  1980  (a)   AND  (b) 

transformer  is  not  being  used  economi- 
cally. For  instance.  350  kv-a,  three- 
phase,  at  220  volts  will  .give  full  load  on 
the  secondaries  of  the  bank,  whereas  if 
built  for  220  volts,  it  would  deliver 
600  kv-a.  J.  F.  i>. 

1981 — Nondon  Valve — What  are  the  es- 
sentials of  a  Nondon  Valve?  Ex- 
plain the  most  suitable  connection  for 
general  use?  What  is  its  efficiency 
and  power  factor?  Why  is  the  volt- 
age reading  across  the  direct-current 
circuit  sometimes  higher  than  the  al- 
ternating line  current?  What  are 
the  troubles  most  generally  encoun- 
tered with  the  use  of  this  valve  and 
how  are  they  overcome.  c.  c.  Q. 

The  essentials  of  the  Nondon  valve 
consist  of  a  metallic  cathode  of  small 
surface,  an  anode  of  large  surface  and 
the  electrolyte.  The  anode  may  be 
either  of  lead,  polished  steel  or  carbon; 
it  is  without  influence  upon  the  valve 
effect,  if  its  relative  surface  is  suflici- 
ently  large.  The  cathode  must  be  of 
pure  aluminum  or  an  aluminum  alloy 
with  a  very  small  proportion  of  other 
metals.  The  surface  of  the  cathode 
must  be  relatively  small  because  alumi- 
num hydroxide  forms  on  it  which  tends 
to  prevent  the  current  flow  between  the 
electrodes.  A  small  cathode  surface  in- 
sures a  more  effective  forming  and 
breaking  down  of  this  surface  resistor. 
The  electrolyte  is  generally  a  concen- 
trated solution  of  one  of  the  following 
phosphate  or  sodium  bicarbonate.  So- 
dium bicarbonate  has  been  found  desir- 
able to  use.  as  the  results  arc  almost  as 
good  as  obtained  with  the  more  expen- 
sive salts.  Fig.  (a)  shows  an  arrange- 
ment of  connections  suitable  for  general 
use.  employing  four  cells  in  order  to 
rectify  both  halves  of  the  current  wave 


and  also  to  increase  radiation  of  heat 
generated.  .Arrows  in  Figs,  (a)  and 
(b)  indicate  the  path  of  the  current 
during  each  alternation.  With  the  cells 
working  properly,  an  efficiency  between 
65  and  75  percent  may  be  obtained. 
.\  home-made  rectifier  will  probably 
have  an  efficiency  of  about  50  percent. 
The  power- factor  is  never  above  90  per- 
cent, but  is  not  necessarily  low  if  the 
cellls  are  operated  at  full-load.  The 
tnost  efficient  method,  for  controlling 
the  direct-current  voltage,  is  placing  a 
variable  reactance  in  the  alternating- 
current  circuit  .as  shown  in  Fig  (a) 
Ihe  Nondon  valve  acts  both  as  a  recti- 
fier and  a  condenser.  The  capacity  be- 
tween the  aluminum  plate  and  the'clec- 
trolyte  is  about  one  microfarad  for 
every  seventeen  square  inches  immer- 
sed;  the  dielectric  consisting  of  the  thin 
film  .  formed  by  the  current  action 
When  the  current  flows  through  the  cell 
from  the  iron  to  the  aluminum  the 
amount  of  electricity  stored  is  negligible 
due  to  the  small  resistance;  however, 
when  a  reversal  takes  place  a  static 
charge  is  accumulated  depending  on  the 
•ilternating-current  voltage.  When  the 
current  is  flowing  through  cells  ^  and  3 
only,  as  shown  in  Fig.  (a),  cells  ;  and  ./ 
will  be  charged  to  the  potential  of  the 
alternating  e.  m.  f.  On  the  next  rever- 
sal the  path  of  the  current  is  as  indi- 
cated by  arrows  in  Fig.  (b)  so  that 
static  charge  in  cells  I  and  ./  will  tend 
to  increase  the  flow  of  current  through 
direct-current  meter.  This  increase  of 
flow  only  becomes  appreciable  when  a 
high  resistance  voltmeter  is  connected 
across  the  direct-current  terminals. 
When  a  Nondon  valve,  having  the 
proper  value  of  capacity,  is  connected 
across  an  alternating-current  supply,  in 
series  with  a  reactance  coil,  they  will 
form  a  resonant  circuit  and  the  voltage 
reading  across  the  alternating-current 
valve  terminals  will  be  greater  than  the 
line      voltage.     Sparking     between      the 


13 


3B 


/iT"^  ,  (i^ 

lal 

13-1  W3 

1  "^ —  ■ 

rr.  ^^ 

— »• 

FIGS.    I981    (a)    AND    (b) 

aluminum  plates  and  the  surface  of  the 
electrolyte  can  be  prevented  by  covering 
the  surface  of  the  li<|uid  with  oil  or 
wrapping  the  aluminum  plate  with  fric- 
tion tape  to  a  point  about  one-half  inch 
below  the  surface  of  the  liquid.  To 
start  a  rectifier,  it  is  necessary  to  place 
a  rheostat  or  a  lamp  bank  in  the  alter- 
nating-current side  to  limit  the  flow  of 
the  current  until  a  film  of  aluminum 
hydroxide  has  been  formed.  To  insure 
good  results  cleanliness  in  handling  the 
electrolyte  is  essential  and  the  salts  must 
not  contain  too  high  percentages  of  sul- 
phates or  chlorides.     G.  c.  d.  &  m.  m.  b. 


io8 


THE   ELECTRIC  JOURNAL 


\o\.  X\'in,  No. 


— 

— 

MMLWAY  ©FJ^MATHM^  PAT  A 

The    purpoae    of    thia    section    is    to    present         The   co-operation   of  all   those    interested    In 
accepted  practical  methods  used  by  operating         operating  and  maintaining  railway  equipment 
companies    throughout    the    country                      is    invited.      Address    R.    0.    D.    Editor. 

— 

— 

THE 
ELECTRIC 
JOURNAL 

MARCH 
1921 





Armature  Record  Tags 


Repair  shops  connected  with  all  the  larger  street  railway 
systems,  as  well  as  some  of  the  smaller  ones,  have  methods  of 
keeping  records  which,  in  practically  all  cases,  are  different  as 
the  system  of  records  used  with  the  various  forms  have  de- 
veloped along  with  the  growth  of  the  company.  In  some  in- 
stances these  systems  have  grown  to  such  an  extent  as  *«  be- 
come expensive  to  maintain  and  more  or  less  of  a  burden, 
while  in  others  they  have  been  neglected  and  poorly  kept  up 
and  in  this  condition  are  worthless,  for  all  practical  purposes. 
Like  all  questions  of  this  nature,  there  is  a  wide  difference  ot 
opinion  among  master  mechanics  as  to  the  value  and  import- 
ance of  keeping  suitable  records,  which  is  in  part  responsible 
for  the  wide  range  of  systems  of  records,  reports,  forms,  etc., 
found  on  the  various  railways  properties. 

In  spite  of  this  condition,  all  operators  seem  to  agree  upon 
the  importance  of  keeping  some  specific  information  as  to  the 
condition  of  their  motor  armatures,  and  a  great  variety  ot 
printed  forms  in  the  shape  of  cards  and  tags  are  to  be  found  in 
use  With  this  in  mind,  and  with  the  idea  of  interesting  the 
smaller  operators  who  now  largely  depend  more  or  less  upon 
the  memory  of  the  winder  as  to  the  armature  troubles  and  re- 
pairs a  sample  armature  tag  will  be  explained  in  detail  to  en- 
courage the  keeping  of  some  dcfinile  records  on  this  important 
part  of  the  equipment. 

FRONT   OF  TAG 

The  general  scheme  is  as  follows :— When  an  armature  is 
taken  from  its  motor  frame,  the  following  information  should 
be  written,  preferably  in  ink,  on  the  front  side  of  tag  by  the 
man  in  charge  of  the  work. 

Armature   Serial   Number— Found   stamped   on    the   end 

of  the  shaft.     When  shaft  renewals  are  made  sec  that 

the  serial  number  of  the  old  shaft  is  stamped  on  the 

end  of  the  new  one. 

Type  of  Motor— This  is  marked  on  the  motor   frame  or 

commutator  lid. 
Car  Number— As  painted  on  the  side  of  the  car. 
Position  of  Motor— Location  on  truck  under  the  car. 
Station— Operating    station    or    motor    assembly    floor   of 

shop. 
Date— Month,  day  and  year. 
Why    Removed— Give    briefly    reasons    for    removing    the 

armature. 
Cause  of  Trouble— What  happened  to  make  it  necessary  to 

take  the  armature  from  the  frame. 
Condition  of  Frame— State  condition  of  field  coils,  wiring 

around  frame,  brushholder,  bearings,  etc. 
The  tag,  when  tilled  in,  is  to  be  signed  by  the  barn  foreman 
and  securely  tied  to  the  armature  shaft. 
BACK  OF  TAG 
When    an    armature    reaches    the    winding    room    for    in- 
spection or  repair,  the  tag  should  be  removed  until  all  work  is 
completed  or  the  armature  is  ready  to  be  shipped.     The  tag  is 
then   marked  with  the   following   information   by   the   winding 
room  foreman ; — 

Work   Done — All   work  done  on  the  armature  should  be 
checked  in  the  small  squares  provided  in  front  of  the 
various  operations  indicated. 
Remarks — In  general  statements,  such  as  the  condition  of 

the  insulation  on  the  coils,  etc. 
Tested  and  Appro\'ed — Indicate  the   date  work  was  com- 
pleted and  approved. 
This  part  of  the  tag  should  be  signed  by  either  the  winding 
room  foreman  or  the  shop  foreman  and  the  tag  tied  securely  to 
the  shaft  before  the  armature  leaves  the  winding  department. 
When  the  armature  is  received  at  the  car  barn  or  motor 
assembly  floor  of  the  shop,  the  tag  is  not  disturbed  until  the 
armature   is   put   back   into   service.     Before   the   armature   is 
mounted  in  a  frame,  the  tag  is  removed  and  the  following  in- 
formation recorded  thereon : — 


Car  Number — Number  of  car  on  which  motor  is  mounted. 
Motor  Number — Location  on  truck  under  car. 
Station — Operating   station   or   motor   assembly   floor. 
Date — Month,  day,  year. 

The  card  is  then  signed  by  the  barn  foreman  and  sent  to 
the  otTice  of  the  master  mechanic  for  record  and  tile. 

ASVAHTAGES    OF   THE    PROPOSED   TAG 

It  is  suggested  that  the  master  mechanic  give  this  tag, 
modified  to  meet  local  requirements,  if  necessary,  a  fair  trial 
over  a  period  of  from  six  months  to  a  year,  to  check  the  utility 
of  keeping  a  definite  record  of  armature  failures  and  repairs. 
The  following  shows  some  of  the  advantages  that  will  result 
from  keeping  of  such  records. 

I — It   provides   an   accurate   record   of   armature   troubles!. 
3 — It    provides    an    accurate    record    of    armature    repairs. 
S — It  furnishes  an  accurate  record  of  the  location  of  arma- 
tures in  the  equipment. 
4 — It   provides   means   of   analyzing   armature   and   motor 
failures.  (If  the  same  armature  serial  is  in  for  repairs, 
frequently  you  are  in  a  better  position  to  run  down  the 
trouble   from  the  records.) 
5 — It  gives  a  record  of  life  of  motor  parts. 
6— It  helps  to  weed  out  defective  frames,  and  troubles  due 
to  incorrect  winding  and  motor  connections. 


® 


ARMATURE  TAG 


Out  of  Car  No 

Out  of  Motor  No 


Cau»c  of  Trouble 


Work  Done 

D  New-  Windtnga     O  Repair  Windinj 
a  Rebandcd              D  Oeancd*.  Pjim 
a  Com.Tumed         D  Com.  Slotted 
D  Striiitthtoi  Shaft   D  Dipped  ; 
n  C  E   Bearing*       D  P.E.  Be; 
Remarks 


® 


Bakt 


Anhaturf  Put  In 


Motor  No      \-2i-^ 


FIG.    I — front  and  back  OF  THE  PROPOSED  ARMATURE  TAG 

7 — It  requires  little  clerical  work. 

,V — It  assists  in  figuring  cost  of  repair  parts  on  armatures. 

9 — The  benefits  resulting   from  the  records  on  these  tags 

will  readily  be  seen  and  will  lead  to  an  extension  of 

this  system  of  records. 

SUGGESTIONS   FOR  TAGS 

The  following  points  are  suggested  as  worth  considering 
in  connection  with  the  adoption  of  armature  tags  for  use  in 
railway  shops. 

/ — Adopt  a  standard  size  which  can  be  secured  from  stock, 

such  as  S-yi  by  z-H  inches. 
2 — A  cloth  tag  is  more  durable. 
j__On  some  properties  the  tags  are  provided  with  envelopes 

which  can  be  tied  shut,  thus  keeping  the  tags  clean  and 

making  the  records  more  legible. 
^ — The    suggested    records    should    be    modified    whenever 

necessary   to  meet  the  local   requirements  more   fully. 
5 — Either   file   the   tags   for   future   record,   or   record  the 

same  information  on  suitable  cards  kept  in  the  master 

mechanic's  ofiice.  John  S.  Dean 


The  Electric  Journal 


VOL.  XVIII 


April.  1921 


No.  4 


Radio — 
Its  Future 


Looking  into  the  future  of  radio  de- 
velopment one  sees  possibilities  of 
great  expansion  in  an  almost  limitless 


field.  The  uses  to  which  radio  can  be  put  are  greatly 
diversified,  and  it  is  certain  to  create  as  epochal  changes 
in  our  accepted  everyday  affairs  as  did  the  introduction 
of  the  telegraph  and  telephone,  and  the  application  of 
electricity  to  the  street  railway  and  to  lighting. 

Already  the  commercial  transmission  of  messages 
by  radio  telegraphy  is  well-established.  The  speed  of 
this  transmission  and  the  reliability  of  the  radio  .systems 
as  compared  with  wire  and  cable  systems  are  favorable 
to  the  former.  For  long  distance  work  the  radio  sys- 
tems have  greater  capacity,  can  handle  more  traffic  and 
the  operation  is  performed  at  lesser  tolls. 

Following  the  developments  of  radio  telegra[)hy, 
great  advances  are  now  being  made  in  radiophone  de- 
velopment. It  is  not  to  be  assumed  that  the  radiophone 
will  displace  the  present  wire  telephone;  rather  that  it 
will  broaden  the  field  of  communication  by  the  develop- 
ment of  its  own  special  advantages,  which  are  more 
or  less  distinct  from  those  of  the  wire  telephone,  as  it 
possesses  the  feature  of  widest  publicity,  as  compared 
with  the  secret  or  practically  private  character  of  the 
wire  telephone.  The  two  together  will  make  many  new 
applications  possible,  and  it  has  now  become  practicable 
to  converse  on  the  sea,  in  the  air  or  on  moving  trains, 
to  one's  own  office  or  home,  exactly  as  with  land  tele- 
phonic communication. 

There  is  no  doubt  that  in  the  very  near  future  the 
radiophone  will  be  largely  employed  over  long  distances 
in  sparsely  settled  districts  where  other  communication 
facilities  are  not  now  available.  When  it  is  considered 
that  wherever  wire  systems  reach  there  must  be  pole 
lines  which  are  subject  to  damage  by  storms  and  other 
agencies,  it  can  be  seen  how  tremendously  radio  over- 
comes conditions  of  cost  of  installation,  maintenance 
and  reliability  of  service,  which  cannot  be  met  advan- 
tageously by  the  wire  systems. 

The  adaptability  of  the  radiophone  to  broadcasting 
reports,  news,  entertainments,  concerts,  lectures,  etc., 
creates  a  field  particularly  its  own,  and  it  is  reasonably 
certain  that  the  future  will  see  many  changes  in  the 
present  accepted  methods  of  conducting  such  functions 
and  entertainments.  It  is  quite  possible  that  especially 
constructed  transmitting  rooms  will  be  provided  for 
such  purposes,  so  that  voices  and  music  will  be  broad- 
casted through  unbounded  areas  and  listened  to  by  in- 
visible and  widely-distributed  audiences  of  vast  num- 
bers. The  same  opportunities  would  thus  exist  for  the 
country  dweller  as  for  the  city  resident,  and  inmates  of 
hospitals  and  sanitariums,  and  sick  people  and  invalids 
in  the  home  would  have  opportunities  for  pleasures  and 


diversions  now  denied  them.  .V  transiuilling  >ysiem  of 
this  character  would  have  the  further  great  advantage 
of  doing  away  with  the  necessity  of  appearing 
in  person  in  public  halls  and  auditoriums,  the  capacities 
of  which  at  best  are  quite  limited. 

The  importance  of  reaching  such  tremendous  num- 
bers of  people,  with  practically  no  effort,  offers  great 
possibilities  for  advertising  and  the  distribution  of  news 
and  important  facts,  and  in  reality  introduces  a  "uni- 
versal speaking  service."  It  is  not  unreasonable  to 
predict  that  the  time  will  come  when  almost  every  home 
will  include  in  its  furnishing. some  sort  of  loud-speaking 
radio  receiving  instrument,  which  can  be  put  into  opera- 
tion at  will,  permitting  the  householder  to  be  in  more  or 
less  constant  touch  with  the  outside  world  through  the.se 
broadcasting  agencies. 

The  application  of  radio  to  industrj'  presents  a  vast 
undeveloped  field  of  enormous  possibilities.  There  are 
great  possibilities  in  all  methods  of  signaling,  particu- 
larly in  railroad  operation  for  the  dispatching  of  trains 
and  for  use  as  a  means  of  communication  over  areas 
served  by  power  transmission  companies.  During  the 
World  War  it  was  conclusively  demonstrated  that  radio 
is  an  indispensable  agency  in  the  directing  of  air  planes 
and  vessels,  and  in  directing  and  controlling  the  move- 
ment of  armies  on  the  battlefields. 

To  what  extent  power  can  be  transmitted  by  radio 
is  as  yet  problematical,  but  it  is  possible  even  now  to 
perform  this  important  function  in  a  minor  way,  so  that 
electric  relays  can  be  operated  at  a  distance,  thus  per- 
mitting the  putting  into  operation  of  independent 
sources  of  power  to  direct  and  control  various  me- 
chanical devices.  As  time  progresses  and  knowledge 
increases,  this  field  will  undoubtedly  be  greatly  ad- 
vanced and  developed. 

The  field  of  radio  application  is  practically  un- 
limited in  the  important  affairs  of  the  world,  and  its  de- 
velopment will  mark  one  of  the  great  steps  in  the  pro- 
gress and  evolution  of  mankind.         H.  P.  Davis 


The  development  of  the  radio  art  has 
Radio  opened    avenues    of    communication 

Its  Relation   to    where  the  rapid  transmission  of  mes- 
the  Electrical      sages  was  previously  impossible  and 
Industry  is    still    impracticable    by    any    other 

means.  For  communication  from 
ship  to  ship  or  from  ship  to  shore;  for  communication 
between  airplanes  or  between  airplanes  and  land  sta- 
tions; for  accurately  locating  directions  at  long 
distances  for  ships  and  airplanes;  for  communica- 
tion between  rapidly  moving  trains  and  the  dis- 
patchers office ;  for  communication  to  and  from  regions 
isolated      bv      deserts,      forests      or     mountains;      in 


THE  ELECTRIC  JOURNAL 


Vol.  XVril,  No.  4 


short  for  quick  communication  wherever  the  in- 
stallation of  wires  is  impossible  or  prohibitively  ex- 
pensive, radio  reigns  supreme. 

Radio  must  not,  however,  be  considered  entirely 
from  the  standpoint  of  communication.  The  electrical 
mdustry  as  a  whole  is  closely  allied  with  the  radio  de- 
velopments. Some  of  the  greatest  advances  that  have 
been  made  in  the  electrical  art  in  the  last  decade  have 
been  interconnected  with  devices  and  circuits  of  the 
kmd  that  are  used  in  the  radio  system.  Devices  which 
were  no  more  than  experimental  laboratory  equipment 
a  few  years  ago,  or  have  developed  from  laboratory  ex- 
periments, now  are  of  great  commercial  importance.  As 
typical  examples  may  be  cited  the  use  of  tuned  circuits 
at  commercial  frequencies,  such  as  the  impedance 
bonds,  or  resonant  shunts  which  form  an  essential  part 
of  60  cycle  signal  circuits  on  25  cycle  electrified  rail- 
ways ;  the  impulse  gap  lightning  arrester ;  the  rectigon 
or  hot  cathode  rectifier  for  charging  small  batteries ;  the 
high  frequency  induction  furnace ;  the  telephone  relays, 
v;hich  have  made  transcontinental  telephony  a  commer- 
cial possibility;  the  "wired  wireless"  system  of  multiple 
telephony  whereby  several  telephone  conversations  as 
well  as  a  number  of  telegraph  messages  are  transmitted 
simultaneously  over  a  single  pair  of  wires — to  mention 
only  a  few  of  the  more  spectacular  of  such  develop- 
ments. 

The  electrical  engineer  had  made  no  application  of 
the  electron  theory  until  the  laboratory  developments  of 
the  last  decade  were  transformed  into  commercial  pro- 
ducts. More  has  been  learned  about  the  fundamental 
principles  of  electricity  and  the  nature  of  electrical 
phenomena  by  the  recent  researches  and  developments 
in  this  field  than  in  any  other.  It  is  reasonable  to 
assume  that  the  deeper  insight  which  is  thus  being 
gained  into  the  principles  of  electro-physics  will  have  a 
far  reaching  effect  along  widely  divergent  lines  of  elec- 
trical activity.  '  W.  S.  Rugg 


Some  nineteen  years  ago,  when   M. 

"  .  ^  ^  Leblanc,  the  noted  French  engineer, 

^  was   in   this   countiy,   he   asked   Mr. 

.  ,  ^         Westinghouse     for    a     10  000    cycle 

Alternator  ,,        ^        .  .  •  ■     \  ■, 

alternator    for    certam    expernnental 

v.ork.  Shortly  afterwards  the  machine  was  designed 
and  built.  The  results  obtained  from  the  completed 
machine  were  considered  of  sufficient  interest  to  present 
before  the  American  Institute  of  Electrical  Engineers 
in  1904,  and  the  original  publication  of  seventeen  years 
ago  is  reproduced  in  this  number  of  the  Journal.  As 
far  as  the  writer  remembers,  machines  of  10  000  cycles 
per  second  had  been  attempted  previously,  but  not  in 
what  would  now  be  considered  as  satisfactory  construc- 
tions. He  undertook  to  design  this  machine  along  thor- 
oughly practical  lines.  In  fact,  the  general  tendency  in 
very  recent  high  frequency  alternators  for  radio 
work  on  the  continent,  in  Japan  and  now  in  this  coun- 
try, is  so  nearly  along  the  lines  of  this  earlv  machine 


that  M.  Latour,  the  well  known  French  engineer,  has 
designated  this  early  machine  as  the  "normal  type". 

Previous  lo  this  early  machine,  apparently  all  at- 
tempts were  along  constructions  without  iron  in  the 
armature.  Such  machines,  in  general,  have  been  tried 
repeatedly,  for  ordinary  frequencies,  and  all  have  been 
abandoned.  In  other  words,  the  iron-cored  type  of 
alternator  has  been  the  only  survival  for  any  kind  of 
sei"vice.  This  early  machine,  built  by  the  Westinghouse, 
Company,  may,  therefore,  be  said  to  have  anticipated 
modern  high  frequency  construction  in  general,  and 
even  in  detail  for  certain  designs.  In  working  out  the 
designs  for  some  high  frequency  radio  machines  of 
large  capacity,  quite  recently,  and  considering  all  the 
possible  types  and  constructions,  the  whole  matter 
narrowed  down  finally  to  a  construction  which  is  almost 
identical  with  this  machine  of  nearly  nineteen  years  ago. 

In  the  design  of  this  machine,  nineteen  years  ago, 
the  writer  recognized  that,  from  the  mechanical  stand- 
point, an  iron-cored  construction  for  the  armature  was 
a  practical  necessity,  if  a  reliable  and  durable  machine 
were  to  be  obtained.  An  iron  core,  at  this  high  fre- 
quency, was  considered  by  many  to  be  impracticable, 
due  to  the  probability  of  excessive  iron  losses.  Recog- 
nizing this  probable  limitation,  the  writer  undertook  to 
make  the  design  practicable  by  so  finely  laminating  the 
armature  core  that  the  losses  would  be  brought  within 
operative  limits.  Apparently  this  was  the  first  verj-  high 
frequency  alternator  with  very  thin  laminations. 

This  early  machine  was  of  the  inductor  type,  not 
because  the  inductor  type  in  itself  is  superior  mag- 
netically or  electrically  over  other  types,  but  simply  be- 
cause it  lent  itself  mechanically  to  high  frequenc}'  con- 
structions. This  was  fundamental,  as  evidenced  by  the 
general  adoption  of  the  inductor  type  for  modern  very 
high  frequency  alternators. 

This  little  machine  of  nineteen  years  ago  was  of 
relatively  small  capacity,  based  upon  the  methods  of 
rating  of  those  days.  As  the  published  results  show, 
the  machine  carried  a  load  of  two  kilowatts  with  an 
armature  iron  temperature  rise  of  16  degrees  C.  and  a 
copper  rise  of  21  degrees  C.  by  resistance.  With  modern 
means  of  cooling  and  methods  of  rating,  this  machine 
probably  could  be  made  to  carry  something  like  five 
times  this  load,  under  which  conditions  it  would  show  a 
quite  respectable  efficiency  for  a  small  high  frequency 
machine. 

This  was  a  prideworthy  little  alternator,  in  view  of 
the  fact  that  it  was  a  first  adventure  into  a  practically 
unknown  field;  and  also  because  high  frequency  ma- 
chines of  fifteen  to  twenty  years  later  are  so  nearly 
.".long  the  same  lines  that  it  may  be  assumed  that  most 
of  the  advances  in  the  construction  of  such  apparatus 
have  been  in  improvements  in  materials  and  in  means 
for  dissipating  heat.  This  first  machine  was  sent  to  M. 
Leblanc,  in  France,  many  years  ago,  and  the  writer  has 
heard  nothing  about  it  since.  It  is  quite  possible  that 
it  is  still  in  existence.  B.  G.  Lamme 


poch  r/la]<iijig  Radi©  fav^amtloiiB  of  [•"Ds^niKlein 


ihi 


S.  M.  KINTNER 

Vice-president, 
International  Radio  Telegraph  Co. 


EVERY  ail  has  its  outstanding  leader, — some 
genius  that  is  gifted  with  a  foresight  almost  akin 
to  prophesy.  So  remarkable  are  many  of  their 
inventions,  so  far  ahead  of  their  time  and  the  practice 
of  the  art,  that  they  are  not  appreciated  until  years 
elapse  and  the  art  grows  abreast  of  their  teachings  and 
learns  their  value. 

Fessenden  is  such  a  genius  in  the  radio  art.  To 
anyone  who  learns  of  his  accomplishments,  by  compar- 
ing his  teachings,  as  recorded  in  the  files  of  the  United 
States  Patent  Office,  with  the  almost  universal  practice 
of  the  radio  art  of  today,  the  truth  of  the  foregoing  will 
be  apparent. 

Fessenden  is  never  satisfied  to  follow  the  "beaten" 
path.  He  is  always  looking  for  other  ways  of  doing 
things.  At  times  he  chooses  the  wrong  lead,  but  he  is 
quick  to  realize  his  mistake  and  to  go  back  and  try  some 
other. 

It  is  this  inborn  characteristic  of  his,  of  being  dis- 
satisfied with  things  as  they  are  and  of  always  trying  to 
improve  them,  that  compels  him  to  invent.  It  is  a  keen 
realization  of  how  things  work,  and  an  almost  super- 
human analysis  of  the  relative  importance  of  the  many 
factors  that  influence  the  result,  that  makes  his  inven- 
tions so  pioneer  in  character. 

In  1899,  when  the  radio  art,  then  called  "wireless", 
was  in  the  beginning  and  the  scientific  world  was  sing- 
ing the  praises  of  the  "coherer",  a  detecting  device  that 
was  then  said  to  be  the  most  sensitive  electrical  instru- 
ment ever  invented  and  so  was  the  one  thing  that  made 
"wireless"  possible,  Fessenden  said :  "No,  that  is  all 
wrong.  The  coherer  will  not  be  used  at  all  in  a  short 
time." 

The  coherer  was  a  trigger  device  which  was  tripped 
when  the  incoining  signals  were  of  sufficient  strength, 
and  so  released  energy  from  a  local  source,  which 
actuated  the  indicating  means.  The  signals  had  no 
character.  One  station  could  not  be  distinguished  from 
another  bv  the  sound  of  its  signal  spark.  Fessenden 
said:  "No  detector  will  survive  that  has  such  charac- 
teristics." 

He  started  to  work  at  once  to  discover  a  detector 
that  would  give  a  response  proportional  to  the  received 
energy, — one  that  utilized  all  of  the  received  energ\-  and 
was  constantly  in  a  receptive  condition.  He  found  not 
only  one  such  detector,  but  several.  Of  these,  the  liquid 
barreter  is  the  best  known  and  was  most  widely  used. 
The  liquid  barreter  held  first  place  among  detectors 
from  1903  until  about  1909. 

Fessenden's  early  discovery  of  this  type  of  de- 
tector, which  enabled  him  to  get  quantitative  results, 
gave  him  a  big  advantage  over  the  other  earlv  workers 


in  the  art  who  continued  to  cling  to  the  coherer.  With 
this  fonn  of  detector,  he  was  early  brought  to  a  reali- 
zation of  possibilities  of  radio  that  were  unthinkable 
with  a  coherer. 

The  invention,  then,  of  this  type  of  detector,  marks 
the  first  epoch  in  Fessenden's  inventions.  Also  it  marks 
the  beginning  of  a  new  fonn  of  radio  transmission. 
The  coherer  worked  best  when  the  radiated  energy  was 
like  a  "whip  crack",  an  explosion  like  the  exhaust  of  an 
automobile  engine  with  the  muffler  open.  It  required  a 
iiig  shock  to  trip  it;  and  all  that  followed,  until  it  was 
reset,  was  wasted.  Fessenden's  device,  on  the  contrary, 
used  all  the  received  energy,  and  so  could  have  it  fed 
out  from  the  transinitter  more  gradually.  It  was  by 
anolog}',  like  exhaust  from  the  automobile  engine  with 
the  muffler  in  use. 

The  advantage  of  the  Fessenden  method  over  that 
preceding  was  in  the  tuning  of  the  receivers.  This 
tuning  made  it  possible  to  select  one  from  several 
simultaneously  operating  transmitting  stations,  each 
■^ending  on  a  different  wave  length,  and  to  exclude  the 
others. 

The  results  secured  were  so  good  that  Fessenden 
sought  to  improve  them  still  further;  and  he  had  the 
marvelous  conception  of  producing  continuous  radia- 
tion by  directly  connecting  a  source  of  alternating  cur- 
rent, such  as  a  high-frequency  alternator,  to  the 
antenna,  w  itli  no  spark  gap  employed  in  any  part  of  his 
system. 

It  is  no  doubt  difficult  for  newcomers  in  the  art, 
now  that  all  oi  the  successful  trans-atlantic  radio  trans- 
mitting stations  employ  that  method,  to  realize  how 
radical  a  departure  he  made  from  the  practice  of  the 
day.  It  may,  however,  serve  a  useful  purpose  to  throw 
a  side  light  on  this  invention  by  quoting  from  no  less  an 
authority  than  Dr.  J.  A.  Fleming,  who  says*: — 

The  patentee  (Fessenden)  considers  that  if  such  an 
aerial,  (one  described  as  having  large  capacity)  were  as- 
sociated with  an  inductance  and  an  alternator  directly, 
no  spark  gap  being  used,  it  would  radiate  very  long  electric 
waves.  It  is  doubtful,  however,  whether  it  would  do  so. 
The  creation  of  an  electric  wave  seems  to  involve  a  certain 
suddenness  in  the  bc.s^inning  of  the  oscillations,  and  an  al- 
ternator giving  a  simple  sine  curve  electro-motive  force 
would  not  be  likely  to  produce  the  required  effect  unless  the 
frequency  of  the  alternator  was  extremely  high." 

Fessenden  had  no  dynamo  of  the  kind  he  required, 
but  he  knew  what  characteristics  such  a  machine  should 
have,  and  plainly  stated  them  in  his  patent  which  was 
issued  in  1902.  Furthermore,  he  set  about  getting  such 
a  machine ;  and,  after  untiring  efforts  on  his  part,  and  a 
great    development    expense    borne    by    his    financial 


*In  the  IQ06  edition  of  his  book  entitled  "The  Principles  of 
Electric  Wave  Telegraphy"— p.  511. 


THE   ELECTRIC  JOURNAL 


Vol.  XVIIT.  Xo.  4 


backers,  he  succeeded  in  securing  one  from  the  General 
Electric  Compan)-  in  Sept.  1906. 

Another  radical  departure  was  made  in  addition  to 
the  proposal  to  use  a  dynamo, — that  was  the  recommen- 
dation to  use  a  frequency  of  100  000  cycles  per  second 
instead  of  1 000  000,  or  more  cycles,  as  was  then 
thought  necessary.  How  much  of  a  departure  that  was, 
will  be  appreciated  when  it  is  realized  that  the  radiation 
varies  as  the  square  of  the  frequency,  hence  with  one- 
tenth  the  frequency,  but  one-hundredth  of  the  energy^ 
will  be  radiated  for  the  same  antenna  current  in  the 
same  aerial.  There  are,  however,  other  factors  that 
enter,  particularly  in  the  long  distance  transmission,  that 
more  than  overbalance  the  apparent  loss,  and  today  the 
world's  most  powerful  station  has  a  frequencv  of  onh- 
12  500  cycles, — a  wave  length  of  24000  meters. 

The  invention  of  the  method  of  continuous  genera- 
tion is  Fessenden's  second  epoch  making  contribution 
to  the  radio  art. 

With  a  detector  and  receiver  that  ga\-e  quantitative 
indications  and  with  the  idea  of  continuous  radiation, 
Fessenden  conceived  the  plan  of  controlling  the  radia- 
tion in  accordance  with  sound  waves  and  thus  having  a 
radio  telephone.  He  proceeded  to  test  out  his  idea,  and 
was  successful  in  proving  it,  several  years  before  he 
secured  his  dynamo  to  produce  continuous  radiation,  by 
the  use  of  modulated  waves  from  spark  discharges  at 


the  rate  of  several  thousands  per  second.  However, 
\ery  shortly  after  receipt  of  his  first  high  frequency 
alternator,  he  was  able  to  transmit  radio  phone  messages 
over  distances  of  several  miles.  In  some  of  these  early 
demonstrations,  he  perfected  methods  of  control  of  the 
radio  phone  which  enabled  him  to  talk  from  a  wire  line 
phone  to  the  radio  station,  where  the  received  message 
was  automatically  and  accurately  relayed  over  a  num- 
ber of  miles  by  radio  telephone,  and  at  the  radio  receiv- 
uig  station  was  again  automatically  put  back  on  the 
wire  line  for  delivery  to  the  distant  person  listening. 

The  radio  phone  is  the  third  epoch  making  inven- 
tion of  Fessenden. 

There  are  a  number  of  other  Fessenden  radio  in- 
\entions  that  merit  some  mention,  but  space  limitations 
make  it  necessarj-  to  omit  all  but  one  more,  the 
heterodyne*.  The  heterodyne  method  is  the  best  yet  de- 
vised for  the  reception  of  continuous,  or  undamped 
waves.  It,  with  continuous  wave  generation,  has  made 
trans-atlantic  radio  operations  practicable. 

The  heterodyne  then  is  the  fourth  epoch  making 
radio  invention  of  Fessenden. 

What  other  radio  inventor,  American  or  Foreign, 
can  point  to  as  many  inventions  of  equal  importance? 


*See  article  on  this  subject  by  Mr.  J.  V.  L.  Itogaii,  in  tbis 
issue,  p.  116. 


La:l'ayoj:iD  Radio  Sintlom 

COMMANDER  S.  C.  HOOPER,  U.  S.  N. 


THE  Lafayette  high-power  radio  station  at  the  vil- 
lage of  Croix  d'  Hins,  France,  about  fifteen  miles 
from  Bordeaux,  the  construction  of  which  was 
undertaken  during  the  war  by  the  United  States  Navy 
in  conjunction  with  the  French  authorities  for  the  pur- 
pose of  insuring  adequate  and  reliable  communication 
facilities  between  the  United  States  Government  and 
the  American  Expeditionary  Forces  in  France,  was 
formally  turned  over  by  representatives  of  the  Navy  to 
the  French  Government  on  December  18,  1920,  and  the 
station  was  then  formally  inaugurated  in  the  inter- 
national wireless  service  of  the  world. 

The  construction  of  a  super  high-power  radio  sta- 
tion in  France  was  deemed  necessary  after  the  entrance 
of  the  United  States  into  the  World  War,  in  view  of 
the  extremely  heavy  and  constantly  increasing  volume 
of  trans-Atlantic  traffic  being  handled  by  the  ocean 
cables,  and  the  not  remote  possibility  that  this  means  of 
communicating  with  our  forces  abroad  might  be  inter- 
rupted. 

It  was  decided,  therefore,  to  establish  a  super  high- 
power  radio  station  in  France  which  would  be  capable 
of  communicating  with  the  American  stations  during  all 
periods  of  the  day  and  night  and  all  seasons  of  the  year 
regardless  of  possible  interference  from  the  powerful 


station  at  Nauen,  or  from  atmospheric  disturbances 
prevailing  during  the  summer  months.  Accordingly  the 
Navy  Department  was  entrusted  with  the  task  of  estab- 
lishing a  station  in  France  which  would  be  not  less 
than  twice  as  powerful  as  any  radio  station  then  in 
existence. 

The  construction  of  the  station  was  far  advanced 
when  the  armistice  was  signed,  at  which  time,  however, 
all  work  was  stopped,  as  the  very  urgent  need  of  the 
station  was  no  longer  apparent.  Later,  however,  the 
French  Government  requested  that  the  station  be  com- 
pleted as  an  after  war  measure,  and  work  was  again 
resumed  and  carried  to  completion. 

The  principal  engineering  features  of  the  Lafayette 
radio  station  are  eight  self-supporting  steel  towers  each 
820  feet  in  height,  resting  on  immense  concrete  foun- 
dations which  rise  12  feet  above  the  ground  level ;  the 
antenna  system,  and  the  transmitting  equipment  consist- 
ing of  looo-kw  arcs  complete  in  duplicate. 

The  eight  towers,  resting  on  their  foundations,  thus 
providing  a  height  of  832  feet  from  the  ground  level  to 
the  tops  of  the  towers,  are  arranged  in  two  rows  of  four 
each,  the  rows  being  spaced  1320  feet,  and  the  towers  in 
each  row  likewise  being  spaced  1320  feet  apart;  giving 
a    total    antenna    area    of    5  227  200    square    feet,    this 


April,   1921 


THE   ELECTRIC  JOURXAI. 


"3 


antenna  area  far  exceeding  that  of  an}'  other  existing 
radio  station. 

The  antenna  is  of  the  inverted  "L"  t}pe,  the  longi- 
tudinal antenna  wires,  consisting  of  number  three 
silicon-bronze  cable,  being  supported  by  triatics  stretch- 
ing across  the  aisle  formed  by  the  two  rows  of  towers. 

The  arc  equipment  is  of  the  Federal  Poulsen  type 
and  is  capable  of  withstanding  a  25  percent  overload, 
thereby  making  1250  kw  available  intermittently  for 
short  periods  of  time.  The  contract  for  the  arc  trans- 
mitting equipment  called  for  the  delivery  of  a  high  fre- 
quency current  of  500  amperes  continuously  on  a  wave 
length  approximately  three  times  the  natural  period  of 
an  antenna  having  a  true  capacity  of  0.047  microfarad 


FIG.    I  —  M.MX    BUILDING    .\ND   820    FOOT    SELF-SUPPORTING    STEEL 
TOWERS  OF  THE  L.\F.\YETTE  RADIO  ST.\TIOX 

and  a  t(_nal  continuous  undam[ied  wave  radio  frequency 
resistance,  e.\clusi\e  of  radio  apparatus  and  connec- 
tions, not  to  exceed  1.3  ohms  under  operating  condi- 
tions. 

The  characteristics  of  the  antenna  system  and 
oscillatory  circuit,  as  pei'manently  installed,  are  outlined 
below : — 

Capacity   0.05     microfarad 

-■Antenna   resistance    0.45   ohm 

Ground   resistance    0.90  olim 

Loading  inductor  and  connections   0.30  ohm 

1  otal  oscillatory  circuit  resistor  1.65  ohms 

.\ntenna  natural  period   S130  meters 

Effective  antenna  height    172  meters 

The  average  height  of  the  antenna  horizontal  wires 
is  650  feet,  which  shows  the  average  sag  of  the  wires 


to  be  182  feet,  since  the  tops  of  the  towers  are  832  feet 
above  ground  level.  The  equipment  was  adjusted  to 
live  wave  lengths,  namely,  13  900,  16  300,  18  700,  21  200 
and  23  500  meters,  the  latter  being  considered  as  the 
contract  wave  length  for  the  purpose  of  acceptance 
tests.  A  maxiiiuim  antenna  current  of  610  amperes 
was  obtained  without  damage  to  the  installation.  The 
antenna  current  used  during  the  30  day  tests,  \vhich 
were  conducted  from  August  21st  to  September  19th, 
1920,  averaged  about  450  amperes  on  the  various  wave 
lengths. 

The  signals  from  the  Lafayette  station  as  received 
at  Cavite,  Philippine  Islands :  San  Francisco,  Cali- 
fornia ;  Balboa,  Canal  Zone ;  P.ar  Harbor,  Maine,  and 
Washington,  D.  C,  during  the  30  day  tests,  were  of 
from  three  to  eight  times  greater  intensity  than  those 
of  other  high-power  radio  stations  of  the  world  of  ap- 
proximately equal  distances. 

Work  on  the  station  began  on  May  28,  1918  and 
was  completed  on  August  21,  1920.     The  total  cost  of 


FIG.    2 — L.MAVETTE    RADIO    STATIOX 

The  largest  radio  station  in  the  world.  Height  of  tower, 
820  ft;  height  to  top  of  portal,  215  ft;  distance  between  legs  at 
bottom  220  ft ;  distance  between  legs  at  portal,  105  ft ;  distance 
between  legs  at  top,  9  ft.  8.5  in.  ;  weight  of  tower,  550  tons;  dis- 
tance between  towers,  131J  ft.  4  in.;  range  of  operation,  12000 
miles. 

the  station,  which  the  French  Government  has  agreed 
to  assume,  was  approximately  $4000000. 

A  commemorative  tablet  has  been  placed  on  the 

radio  power  building  near  the  main  entrance,  bearing 

the  following  inscription  in  both  English  and  French: 

LAFAYETTE  RADIO  STATIOX 

Croix  d'Hins,  Gironde,  France 

In  Honor  of  General  Lafayette 

Conceived    for    the    purpose    of    insuring 
adequate     and     uninterrupted     trans-Atlantic 
communication    facilities   between   the   Ameri- 
can    Expeditionary     Forces     engaged    in     the 
World  VVar  and  the  Government  of  the  United 
States  of  .America. 
Erected  liy  the  United  States  Navy  in  con- 
junction   willi    and    for    the    Government    of 
France. 

It  is  undersiijod  the  Lafayette  station  will  exchange 
trans-Atlantic  radio  traffic  with  stations  in  the  United 
States  and  acmss  the  continent  of  Europe  and  Asia 
with  the  French  station  at  Saigon,  Indo-China,  and  also 
with  other  high  power  radio  stations  in  various  parts  of 
the  world. 


j)t!^C(i^t!oii  of  a  ^Jiil- 


Way? 


^ 


SiT>;5in!iTiT<  Sy^tora 


for  Arc  Trau-siiiiUoj^^ 


LIEUT.  W 


A.  EATON,  U.  S.  \ 


UNTIL  a  comparatively  recent  date,  most  arc  radio 
transmitting  stations,  both  on  shipboard  and  on 
shore,  used  various  modifications  of  the  so-called 
"Compensation"  or  "Spacing"  wave  signaling  system, 
that  is,  a  system  whereby  the  transmitting  or  "Mark- 
ing" wave  of  a  definite  frequency  is  propagated  when 
the  sending  key  is  depressed,  and  a  compensating  or 
spacing  wave  of  a  different  frequency  is  propagated 
when  the  key  is  open.  The  only  exceptions  to  this  sys- 
tem in  use  to  any  extent  were  arc  transmitters  of  low 
power,  of  the  order  of  two  and  five  kilowatts,  in  which 
the  power  handled  and  the  characteristics  of  the  arc 
were  such  that  the  elimination  of  the  compensating 
wave  was  somewhat  easily  accomplished. 

The  compensation  wave  method  of  signaling  limits 
the  number  of  arc  stations  which  can  be  simultaneously 
operated,  for  the  reason  that  each  station  requires  the 
exclusive  use  of  a  definite  wave  band,  the  width  of 
which  is  determined  by  the  fact  that  there  must  be 
from  one  to  three  percent  separation  between  the  signal- 
ing and  compensating  waves.  Also,  as  is  well  known, 
the  arc  is  rather  prolific  as  regards  harmonics  and 
"m.ush",  which  annoying  source  of  interference  is 
doubled  when  the  compensation  method  of  signaling  is 
used. 

The  chief  advantage  of  the  compensation  method 
of  signaling  was  its  simplicity.  In  the  early  days,  with 
comparatively  few  sustained  wave  stations  in  operation, 
its  use  offered  no  great  disadvantages.  As  the  number 
of  sustained  wave  stations  increased,  however,  objec- 
tions to  the  method  became  so  pronounced  that  indica- 
tions are  that  the  coming  International  Radio  Conven- 
tion will  decide  against  the  continued  use  of  the  com- 
pensation method  of  arc  signaling. 

The  necessity  of  developing  a  suitable  "uni-wave" 
or  single  wave  signaling  system,  therefore,  was  evident. 
A  great  deal  of  experimenting  and  research  work  along 
this  line  has  been  in  progress  during  the  past  two  or 
three  years,  both  in  Government  and  commercial  estab- 
lishments, with  the  result  that  today  it  is  safe  to  state 
that,  as  regards  this  countrj-,  the  problem  has  been 
solved  for  arcs  of  all  powers  now  in  use. 

The  problem  that  confronted  the  Navy  was  the  de- 
velopment of  a  uni-wave  system  which  would  not  be  too 
critical  in  adjustment  and  would  give  positive  and  con- 
sistent operation.  The  consideration  of  various  schemes 
and  circuits  indicated  that  the  most  positive  uni- 
wave  signaling  would  be  accomplished  by  a  circuit  in 
which  the  arc  was  connected  to  the  antenna  when  the 
transmitting  key  was  depressed  and  to  a  dummy 
antenna  or  so-called  "back  shunt"  circuit  when  the  key 


was  opened.  And  this  is  the  scheme  which  is  today  in 
successful  operation  in  a  few  semi-high  powered  sta- 
tions and  is  gradually  being  expanded  into  more. 

A  simple  circuit  accomplishing  the  above  results 
has  been  in  successful  use  with  two  kilowatt  arcs,  and 
is  shown  schematically  in  Fig.  i.  Position  i  shows  the 
arc  connected  to  the  antenna  with  the  transmitting  key 
depressed ;  position  1 1  shows  the  arc  momentarily  con- 
nected to  both  the  antenna  and  back  shunt  circuit  upon 
the  opening  of  the  transmitting  key,  and  position  ill 
shows  complete  separation  from  the  antenna  and  posi- 
tive connection  to  the  back  shunt  circuit.  Upon  again 
pressing  the  key,  the  operation  is  reversed. 

While  the  above  scheme  was  applicable  to  the  two 
kilowatt  arc,  it  was  not  applicable  to  high  powered 
arcs,  due  to  the  violent  flashing  experienced  at  the  con- 
tacts when  the  energy-  was  transferred  from  the  antenna 
to  the  back  shunt  circuit  or  vice  versa.  A  circuit  was 
therefore  devised  which,  retaining  as  far  as  possible  the 
initial   intent  of  completely  disconnecting  the  antenna 


FIG. 


FIG.  2 — USING  RESIST- 
ANCE BETWEEN  AN- 
TENNA        AND         BACK 

SHINT  rUCUIT 


I — UNI-WAVE    OR     SINGLEWAVE 
SIGNALING  SYSTEM 

Disconnecting  antenna  and 
back  shunt  circuit  for  arc  radio 
transmission. 

and  back  shunt  circuit,  makes  use  of  a  bank  of  non-in- 
ductive resistance  units  between  the  arc  antenna  and 
back  shunt  circuits  as  indicated  in  Fig.  2.  It  will  be 
noted  that  the  key  in  this  circuit  introduces  a  compara- 
tively high  resistance,  alternately  into  the  antenna  and 
absorbing  circuits,  thus  rendering  the  circuit  in  which 
the  resistance  is  introduced  aperiodic  for  all  practical 
purposes.  Tests  of  this  circuit  gave  early  indication  of 
a  satisfactory  uni-wave  system.  Not  only  is  the  spark- 
ing at  the  key  contacts  reduced  to  an  absolute  minimum, 
due  to  the  fact  that  the  antenna  and  absorbing  circuits 
are  not  entirely  broken,  but  it  was  found  that  the  ad- 
justments of  the  constants  of  the  back  shunt  circuit  are 
not  at  all  critical,  either  in  wave  length  or  current  bal- 
ance. » 

Thorough  tests  were  made  on  this  circuit  to  deter- 
mine the  most  suitable  form  of  key  and  the  best  con- 
stants for  the  back  shunt  circuit.  Little  difference  was 
noticeable  in  the  action  of  the  different  keys  tested, 
however,  and  the  transfer  of  energy  from  the  antenna 


April,   1921 


THE  ELECTRIC  JOURNAL 


115 


circuit  to  the  back  shunt  circuit  took  place  efficiently 
when  the  constants  of  the  back  shunt  circuit  were 
varied  through  wide  limits.  The  adjustments  are  thus 
not  critical  and  all  tests  made,  indicated  that  the  two 
circuits  operated  entirely  independently  ;  the  key  serving 
primarily  to  transfer  the  arc  from  the  antenna  circuit  to 
the  independent  or  back  shunt  circuit. 

The  final  circuit,  which  was  found  to  work  most 
satisfactorily,  is  shown  in  Fig.  3,  and  consists  of  the  fol- 
lowing component  parts: — 

a — A    transmitting   key,    inclnding    non-inductive    resistance 

units. 
b — .\  back  shunt  circuit  resistance. 
c — A  back  shunt  circuit  inductance. 
d — A  back  shunt  circuit  capacity. 
e — A  double  contact  relay. 
/ — A  Morse  key. 
The  Transmitting  Key : — The  relay  key  consists  of 
eight  pairs  of  contacts,  one  contact  of  each  pair  being 
stationaiy.     Four  pairs,   connected  in   series,   are  used 
for  making  and  breaking  the  back  shunt  circuit  and  the 
other  four,  also  connected  in  series,  are  used  for  the 
antenna  circuit.     Each  pair  of  contacts  is  bridged  by  a 
non-inductive     resistance.       Thus,     when     either     the 
antenna  or  back  shunt  circuit  group  of  contacts  is  open, 
four  of  the  resistance  units  are  in  series  with  that  cir- 
cuit increasing  its  resistance  by  a  like  amount.     The  re- 
lay key  is  actuated  by  two  solenoids,  the  energizing  of 
which  is  controlled  by  a  separate  double  contact  relay. 

The  adjustments  of  the  transmitting  key  must  be 
maintained  at  all  times,  so  that  all  contacts  of  each 
group  make  and  break  simultaneously.  While  this  re- 
quirement is  imperative,  its  fulfilling  is  comparatively 
simple,  since  the  design  of  the  key  has  been  made  to 
facilitate  this  adjustment.  If  this  adjustment  is  not 
properly  made,  it  will  evidence  itself  by  heavier  spark- 
ing at  the  contact  which  is  not  in  alignment.  When 
properly  working,  the  sparking  at  the  contacts  should  be 
extremely  minute.  It  has  been  found  that  the  antenna 
contacts  spark  even  less  than  those  of  the  back  shunt 
circuit,  no  sparking  at  all  being  visible  the  greater  part 
of  the  time. 

The  radiation  ammeter  is  connected  in  the  coinmon 
lead  from  the  arc  to  the  antenna  and  back  shunt  cir- 
cuits, so  that  the  meter  indicates  the  current  in  either 
circuit. 

The  Back  Shunt  Circuit  Inductance  is  of  about  150 
microhenries  for  an  arc  in  the  order  of  30  to  60  kw, 
and  is  made  adjustable,  so  as  to  facilitate  balancing  be- 
tween the  two  circuits. 

The  Back  Shunt  Circuit  Capacity  consists  of  a 
bank  of  standard  0.004  mf.  mica  condensers  connected 
in  parallel.     For  an  arc  on  a  wave  length  of  about  5000 


meters,  and  an  antenna  radiation  of  about  45  amperes, 
five  condensers  are  used. 

The  Double  Contact  Relay,  which  may  be  of  a 
common  commercial  type,  is  actuated  from  the  con- 
tacts of  a  Morse  key  and  is  provided  with  a  double  con- 
tact armature ;  each  contact  controlling  one  electric 
magnet  of  the  transmitting  key. 

The  fact  that  the  constants  of  the  back  shunt  cir- 
cuit are  not  critical  as  regards  current  balance  or  wave 
length,  makes  it  possible  to  adjust  this  circuit  initially 
so  that  no  re-adjustment  is  required  when  the  trans- 
mitted wave  length  is  changed  through  wide  limits. 

The  current  in  the  back  shunt  circuit  should  be  ad- 
justed so  as  to  be  approximately  equal  to  the  antenna 
current.  This  may  be  readily  accomplished  by  an  ad- 
justment of  the  back  shunt  circuit  resistance  and  in- 
ductance.    While  a  balance  between  the  two  circuits  is 


KIG.    3 — SlHEM.\TIC    DI.\(;R.\.\I    of    t'XI-W.WE    .XKC    R.\DIO 
TKANSMITTER 

Final  circuit  which  was  foinid  to  work  most  satisfactorily. 

not  essential  for  satisfactory  operation,  the  balance, 
nevertheless,  should  be  made  so  that  the  load  on  the 
power  equipment  will  be  held  practically  constant. 

The  use  of  the  above  key  in  practical  operation  has 
shown  that  the  emitted  wave  from  the  arc  is  greatly  im- 
proved in  tone  and  as  a  rule  resembles  that  of  an  alter- 
nator or  valve  set.  .Mso  the  radiation  will  be  found  to 
have  increased  as  a  rule  by  as  much  as  12  percent  with  a 
verv  noticeable  reduction  in  arc  harmonics  and  mush. 
The  current-  remaining  in  the  antenna  when  the  Morse 
key  is  raised  is  negligible,  being  in  the  order  of  14  to  Yi 
ampere  out  of  40  amperes  normal  radiation. 

One  of  the  above  signaling  systems  has  daily  been 
in  successful  and  consistent  operation  at  a  station  where 
the  average  antenna  current  is  in  the  order  of  75  am- 
peres. This  current  is  handled  by  the  key  with  perfect 
ease  and  freedom  from  sparking  at  the  contacts. 


'fee  J  (oiorodyne  Recdv^r 

JOHN  V.  L.  HOCAN 

Manager, 

The   International   Radio  Telegraph   Co. 

Past  President, 

Institute  of  Radio  Engineers 


OF  THE  many  inventions  in  the  applied  science 
of  radio  signaling,  a  few  stand  far  above 
all  the  others.  The  heterodyne  receiver  marks 
one  of  the  highest  peaks  of  achievement  in  wireless  com- 
munication, and  probably  has  done  as  much  to  advance 
the  art  as  any  single  invention.  When  Fessenden  de- 
vised this  ingenious  and  eminently  practical  way  of 
selecting  and  amplifying  received  radio  signals,  he 
established  a  system  which,  in  conjunction  with  his 
continuous-wave  transmitters,  now  bids  fair  to  grow 
into  substantially  universal  use. 

The  coined  name  "heterodyne"  is  derived  from  the 
Greek  lieteros  (other)  and  dyne  (force),  the  new  word 
implying  that  the  receiver,  which  it  designates,  makes 
use  of  an  "other  force",  i.e.,  a  force  other  than  that  of 
the  received  signals.  The  heterodyne  does  truly  utilize 
such  a  second  source  of  energj^  for  it  combines  with  the 
signal-producing  effects  of  the  received  electromagnetic 
waves,  the  effects  of  another  series  of  radio 
frequency  oscillations  which  are  locally  gen- 
erated at  the  receiving  station.  The  in- 
vention is  notable  not  so  much  for  the  fact 
that  a  local  source  of  energy  is  used,  as 
for  the  highly  novel  and  effective  ways  in 
which  the  effects  of  the  local  source  are 
combined  with  those  of  the  incoming  sig- 
nals. 

In  order  to  demonstrate  the  action  of 
the  heterodyne  receiver,  let  us  first  look 
into  the  basic  problem  of  receiving  sus- 
tained-wave radio  signals.  The  sustained 
or  undamped  wave  is  a  progressive  electromagnetic  vi- 
bration of  ultra-audible  but  infra-visible  frequency. 
This  wave  is  created  by  the  surging  of  powerful  alter- 
nating-currents, of  similar  radio  frequency,  in  an  ele- 
vated aerial  wire  system  at  the  transmitting  radio  sta- 
tion. The  sustaiiied  wave  passes  out  radially  over  the 
earth's  surface  in  all  directions  from  the  transmitter; 
as  its  energy  is  distributed  over  a  larger  and  larger  area 
the  wave  amplitude  decays,  and  at  any  receiving  point 
it  is  obviously  very  feeble  as  compared  to  its  initial 
value.  Nevertheless,  such  an  electromagnetic  wave,  in 
passing  a  receiving  aerial-wire  system,  is  capable  of 
setting  up  in  the  elevated  conductors  a  small  radio  fre- 
quency alternating  potential  with  respect  to  earth.  If  a 
circuit  from  aerial  wire  to  earth  is  provided,  a  feeble 
radio  frequency  current  will  flow ;  if  the  capacity  re- 
actance of  the  aerial  wires  with  respect  to  earth  is  bal- 
anced-out (for  the  frequency  of  the  arriving  waves) 
by  the  inductive  reactance  of  a  tuning  coil  in  the  circuit, 


FIG.  I 

SIMPLE 

RECEIVING 

SYSTEM 


the  current  will  build  up  by  resonance  to  a  maximum 
value. 

Fig.  I  shows  an  aerial  wire  system  A  connected  to 
earth  E  through  such  a  tuning  coil  L  and  a  very  sensi- 
tive current-indicator  /.  If  we  assume  that  radio 
waves  of  a  frequency  of  looooo  per  second  (which  is 
equivalent  to  a  wave-length  of  3000  meters,  the  wave 
velocity  being  3  X  10*  meters  per  second)  strike  the 
antenna  A,  it  will  necessarily  follow  that  a  small  alter- 
nating voltage  of  this  same  frequency  will  be  induced 
in  the  system.  Since  the  circuit  is  in  effect  closed  for 
currents  of  this  frequency  (because  the  capitance  of 
the  aerial  wires  with  respect  to  earth  may  be  of  the 
order  of  o.ooi  microfarad),  the  voltage  will  result  in  a 
small  100  000  cycle  alternating  current  in  the  system. 
If  the  antenna  capacitance  of  o.ooi  microfarad  is  offset 
by  making  the  inductance  of  the  coil  L  approximately 


srSTAlNED  WAVi; 


2.5  millihenrys,  the  circuit  will  have  minimum  reactance 
for  100  000  cycles  and  consequently  a  maximum  current 
will  be  developed.  Under  these  conditions  a  powerful 
disturbance  might  produce  as  much  as  one  milliampere 
of  current  through  the  indicator  /,  but  the  usual 
quantity  would  be  measured  in  tens  of  microamperes. 

An  oscillogram  of  the  antenna-to-ground  current  is 
shown  in  Fig.  2 ;  a  complete  cycle  occupies  one  one-hun- 
dred-thousandth of  a  second,  so  that  the  twenty-two 
cycles  represented  in  this  figure  consume  only  a  little 
(.ver  one  five-thousandth  of  one  second.  The  ampli- 
tude is  constant;  hence  the  name  "sustained"  or  "con- 
tinuous" or  "undamped"  wave.  Telegraph  signaling 
with  such  waves  is  usually  carried  on  by  interrupting 
their  continuity;  a  stream  of  waves  is  emitted  (and 
hence  received)  for  about  one-twentieth  of  a  second  to 
represent  a  dot  and  for  about  three-twentieths  second 
to  indicate  a  dash.  These  signal  trains  nf  constant 
amplitude   waves   produce,    in   the    receiver,   groups  of 


April,  1 92 1 


THIi   ELECTRIC  JOURS. IL 


constant  amplitude  radio  frequency  current  of  similar 
duration.  The  problem  of  receiving  radio  telegraph 
messages  thus  resolves  itself  into  that  of  observing  the 
duration  of  these  feeble  alternating  currents  of  exceed- 
ingly high  frequency. 

If  the  indicator  of  Fig.  i  were  of  the  thermal  type 
and  capable  of  showing  a  substantial  scale  reading  for  a 
few  millionths  of  an  ampere,  it  might  be  used  as  a 
rather  crude  telegraph  receiver.  Could  such  an  appara- 
tus be  secured,  a  short  deflection  would  indicate  a  dot 
and  a  long  deflection  or  pause  a  dash ;  telegrams  in  the 
Morse  code  could  thus  be  spelled  out  slowly.  In  wire 
telegraphy  aural  reception  was  found  to  be  far  more 
satisfactory  than  visual  operation ;  the  same  is  true  of 
radio  telegraphy,  and  therefore  we  must  find  a  way  of 
generating  sounds  to  indicate  the  radio  frequency  cur- 
rents in  the  receiving  circuits. 

The  telephone  receiver  is  the  most  sensitive  ancT 
most  satisfactory  device  for  producing  sounds  from 
electricity.  However,  a  current  of  looooo  cycles  per 
second  frequency  is  many  times  too  high  to  gi\'e  a  di- 


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Flti.    3 — OFER.\TION    OF  CHOFFER   RECF.IVF.K 

rect  indication  from  a  telephone  receiver;  even  if  it 
were  possible  to  make  the  diaphragm  vibrate  at  this 
rate,  no  sound  would  be  heard  because  the  upper  limit 
of  audibility  is  exceeded  by  some  five  times.  Conse- 
quently some  type  of  frequency  transformation  or 
low'ering  must  be  used. 

Fig.  3  indicates  oscillographically  one  of  the  most 
successful  methods  in  use  prior  to  general  adoption  of 
the  heterodyne.  On  the  uppermost  axis  T  is  shown  the 
train  of  oscillations  in  the  receiving  antenna  during 
part  of  a  dot-signal.  By  inserting  an  interrupter  or 
"chopper"  somewhere  in  the  circuit  the  oscillation-train 
is  broken  up  into  shorter  groups  about  o.ooi  second 
apart,  as  indicated  on  axis  U .  These  .shorter  trains  are 
rectified  or  biased  by  passage  through  a  distorting  con- 
ductor (e.g.  a  crystal  detector)  as  represented  on  axis 
f  ,  and  the  rectified  half  waves  are  collected  in  a  con- 
denser and  discharged  as  direct  current  pulses,  axis  W, 
through  the  windings  of  a  telephone.  Thus  there  will 
be  current  in  pulses  at  looo-per- second  frequency  in  the 
telephone  so  long  as  waves  are  arriving.  These  will 
jiroduce  a  musical  vibration  of  the  diaphragm;  short 
and    long   tones   of    a    pitch    about    two   octaves   above 


middle  C  W'ill  indicate  dots  and  dashes.  The  pitch  of 
the  signal  tone  may  be  changed,  by  altering  the  inter- 
rupter speed,  to  a  value  most  pleasing  to  the  operator. 

The  "chopper"  exists  in  a  number  of  modifica- 
tions, but  all  are  handicapped  in  much  the  same  way. 
Interruptef  troubles  are  common,  usually  much  of  the 
arriving  energy  is  wasted  and  there  is  little  or  no  selec- 
tive power  inherent  to  the  system.  The  prime  defect 
is  that  all  current  impulses  in  the  antenna  circuit,  prac- 
tically regardless  of  their  character  or  frequency,  are 
'"chopped-up"  into  the  same  musical  tone  as  the  signal. 
Thus  the  telephone  receiver  gives  the  same  type  of  re- 
sponse to  interfering  signals  as  to  that  which  it  is  de- 
sired to  receive,  and  it  becomes  exceedingly  difficult  to 
interpret  arri\ing  messages  under  any  but  the  best  con- 
ditions. 

The  heterodyne  receiver  ofiers  a  violent  and  favor- 
able contrast.  Abandoning  all  devices  of  the  inter- 
rupter class,  Fessenden*  devised  a  frequency-reducing 
scheme  based  upon  the  principle  of  beats.  It  was  well 
known  that  if  two  musical  tones  of  slightly  different 
frequency  were  simultaneously  sounded,  an  auditor 
would  hear  not  only  the  two  notes,  but  also  a  flutter  or 


• 


FIG.     4— DVX.\MIC    HE- 
TERODYNE 


FIG.     5 —     ELECTROST.\- 
TIC    HETEKODY.VE 


amplitude  variation  whose  rate  would  be  equal  to  the 
dilterence  in  the  tone  frequencies.  By  the  exercise  of 
a  great  scientific  imagination,  Fessenden  extended  this 
concept  to  the  range  of  radio  frequencies,  far  above 
the  limit  of  sound  audition.  His  suggestion  was  not 
merely  that,  if  a  radio  frequency  elifect  of  say  100  000 
cycles  per  second  were  caused  to  interact  with  another 
of  say  loi  000  per  second,  a  beat  variation  of  1000  per 
second  (an  audible  frequency)  would  be  produced; 
Fessenden  went  farther,  and  proposed  the  use  of  a  gen- 
erator located  at  the  receiving  station  for  the  production 
of  one  of  the  two  radio  frequencies.  By  placing  the 
second  generator  under  the  control  of  the  receiving 
operator  Fessenden  made  it  a  "frequency  determining 
element"  by  means  of  which  the  operator  at  the  receiv- 
ing station  could  control  the  pitch  of  tone  of  the  arriv- 
ing signals  and  also  that  of  interfering  .signals  of  dif- 
ferent but  adjacent  radio  frequencies.  Further,  by 
utilizing  a  radio  frequency  generator  at  the  receiving 
station,  Fessenden's  heterodyne  permitted  a  great 
economy  in  power.  None  of  these  features  would  have 
been  possible  had  he  not  recognized  that  the  generator 
of  one  of  the  two  radio  frequencies  whose  effects  are 

*U.   S.   Patents   1050-141   and   105072S,  R.   .\.   Fessenden. 


ii8 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


combined  could  be  allowed  to  run  continuously, — i.e., 
that,  since  beat  signals  would  be  produced  only  when 
both  frequencies  affected  the  receiver,  it  was  necessary 
to  cut  up  only  one  of  them  into  dots  and  dashes  at  the 
transmitting  station.  > 

Fig.  4  shows  one  of  the  earliest  forms  of  hetero- 
dyne receiver.  The  aerial  to  ground  oscillations  flow 
from  the  antenna  A  through  coil  B  and  C  to  earth  E. 
Coil  C  is  of  small  dimensions  and  is  carried  on  a  mica 
diaphragm  D.  Near  it  (the  assembly  constituting  a 
dynamometer  heterodyne  telephone)  is  mounted  a  fixed 
coil  C,  through  which  flows  the  local  oscillaton,-  current 
generated  by  the  radio  frequency  alternator  G  in  the 
circuit  F  H  C  G.  By  making  the  local  frequency  slightly 
different  from  the  arriving  frequency,  the  resultant 
force  produced  upon  the  diaphragm  D  by  the  interaction 
of  the  alternating-current  fields  of  coils  C  and  C  will 
produce  a  to-and-fro  motion  of  a  frequency  equal  to  the 
difference  between  the  two  oscillation  frequencies. 
Thus,  if  the  received  waves  have  a  frequency  of  loo  ooo 
cycles  per  second  and  the  local  generator  runs  at  loi  ooo 


FIG.    6 — FORM.VTION    OF    UE.ATS 

cycles,  the  diaphragm  will  vibrate  at  looo  cycles  per 
second  and  give  oft"  an  audible  signal  beat  note  so  long 
as  waves  arrive  from  the  transmitter. 

A  study  of  the  dynamometer  heterodyne  will  bring 
out  the  fact  that  the  intensity  of  signal  response  is  de- 
pendent not  merely  upon  the  strength  of  the  received 
waves,  but  also  on  the  strength  of  the  local  current. 
Thus  the  receiver  gives  strongly  amplified  tones  from 
the  desired  signals ;  undesired  signals  of  even  slightly 
different  frequencies  will  produce  beat  tones  of  a 
radically  difterent  pitch,  and  these  are  usually  of  pro- 
portionally smaller  amplitude.  Furthermore,  the  hetero- 
dyne receiver  will  give  maximum  amplification  only 
when  the  received  waves  are  purely  sustained,  for  such 
sinusoidal  oscillations  are  essential  to  maximum  beat 
formation.  This  means  that  impulsive  or  irregular  in- 
terfering disturbances,  such  as  are  produced  by  spark 
transmitters  or  by  atmospheric  (static)  strays,  will  not 
be  amplified  nearly  so  much  as  the  desired  signals.  All 
this  is  due  to  the  unusual  type  of  selective  polarization 
utilized  in  these  heterodyne  receivers.  Bj'  this  func- 
tion an   exceedingly  valuable  means  of  discriminating 


between  desired  and  interfering  signals  has  been  pro- 
vided. 

Fessenden  pointed  out  that  interaction  between 
electrostatic  fields  might  also  be  used  for  heterodyne  re- 
ception. This  arrangement,  which  utilizes  voltage  in- 
stead of  current  effects,  is  shown  in  Fig.  5.  Here  the 
antenna  circuit  passes  from  A  through  the  electrostatic 
telephone  D  and  inductance  B  to  earth  E.  The  elec- 
trostatic telephone  consists  of  a  conducting  diaphragm 
supported  close  to  a  fixed  plate,  the  two  forming  a  con- 
denser. When  a  voltage  is  impressed  upon  the  two 
plates  an  attractive  force  is  set  up  between  them  and  the 
diaphragm  moves  toward  the  fixed  conductor.  By 
varying  the  charging  potential  at  audible  frequency  a 
lone  may  be  produced. 

In  using  the  electrostatic  telephone  for  heterodyne 
reception,  it  is  necessary  to  apply  to  the  telephone  not 
only  the  signal  voltage  but  also  the  locally  generated 
potential.  This  may  conveniently  be  done  by  the  in- 
ductive coupling  between  coils  F  and  B  of  Fig.  5,  coil  F 
being  in  circuit  with  the  local  generator  G  and  the  tun- 


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FIG.    7 — RECTIFIC.^TIO.N  OF  HEATS 

ing  condenser  H.  Under  these  conditions  the  operation 
may  be  graphically  represented  as  shown  in  Figs.  6  and 
7  although,  for  convenience  of  drawing,  the  frequency 
ratio  is  greater  than  in  radio  practice.  Referring  to 
Fig.  6,  the  curve  of  axis  A  may  be  taken  to  represent 
the  voltage  impressed  upon  the  condenser  telephone  by 
the  arriving  signal.  The  curve  of  axis  B  will  then  re- 
present the  potential  due  to  the  local  generator.  This 
is  evidently  of  a  different  frequency,  the  ratio  of  A 
(frequency  NJ  to  B  (frequency  N,)  being  1.25  in  these 
diagrams.  The  curve  along  axis  C  shows  the  algebraic 
sum  of  the  potentials  on  A  and  B;  by  reason  of  the 
difference  in  frequencies  this  resultant  potential  fluctu- 
ates from  maximum  to  minimum  at  the  beat  frequency 
or  A'',  —  N„  cycles  per  second,  as  indicated. 

The  curve  of  axis  C  is  repeated  at  the  top  of  Fig. 
7.  Axis  D  shows  the  same  pulsating  radio  frequency 
voltage  in  effect  completely  rectified ;  this  is  the  process 
performed  by  the  electrostatic  telephone,  for,  although 
there  is  in  it  no  electrical  rectification  or  biasing,  the  de- 
vice nevertheless  produces  a  unidirectional  mechanical 
force  regardless  of  the  polarity'  of  the  applied  potential. 
Thus  on  axis  D  we  have  a  graph   of   the  mechanical 


April,   1921 


THE   ELECTRIC  JOURNAL 


119 


force  applied  to  the  diaphragm  of  the  condenser  tele- 
phone, as  it  acts  in  its  capacity  of  a  perfect  electro- 
mechanical rectifier.  The  diaphragm  itself  by  reason 
of  its  inertia,  cannot  follow  the  rapid  individual  attrac- 
tions, but  will  execute  an  averaged  vibration  somewhat 
as  shown  on  axis  E.  This  slow  vibration  is  of -the 
beat  or  audio  frequency,  and  consequently  gives  rise  to 
an  audible  signal  tone,  just  as  in  the  case  of  the  dynamo- 
meter or  electromagnetic  heterodyne  of  Fig.  4. 

The  electrostatic  heterodyne  possesses  the  same 
amplifying  and  discriminating  characteristics  as  the 
other  forms,  and  is  somewhat  more  sensitive  than  the 
dynamometer  form.  With  high  receiving  aerials,  and 
particularly  with  radio  frequency  amplifiers,  it  is  not 
difficult  to  copy  transoceanic  signals  with  the  electro- 
static heterodyne.  Without  amplifiers,  but  using  the 
large  antenna  of  the  Navy  station  at  Arlington,  Va., 
(which  has  a  maximum  height  of  600  feet),  and  a  small 
Poulsen  arc  as  the  local  source  of  oscillations,  signals 
have  been  received  from  San  Francisco  with  the  elec- 
trostatic telephone  heterodyne. 


KIG.    8 — TVPIC.XL    CIRCUIT    OF    KF.CTIFIER     UKTEkOnVNE 


A  great  increase  in  sensitiveness  of  the  heterodyne 
receiver  was  secured  by  combining  the  local  source  of 
oscillations  with  an  electrically  rectifying  radio  re- 
ceiver*. A  typical  arrangement  of  this  sort  is  shown 
in  Fig.  8.  Signal  currents  are  impressed  upon  the  rec- 
tifying detector  L  from  the  antenna  A  and  across  coup- 
ling B'  L  An  incoming  wave  of  constant  amplitude 
will  produce  a  constant  radio  frequency  potential  across 
the  detector,  and  this  will  result  in  a  uniform  direct 
current  through  the  telephones  M.  When  rajlio  fre- 
quency currents  of  slightly  different  frequency,  from 
generator  G,  are  also  impressed  upon  the  detector  by 
way  of  the  inductive  couplings  F  B'  '  and  B'  I,  a 
radicalh'  changed  condition  exists.  The  local  voltages 
interact  to  produce  potential  beats  across  the  detector; 
the  rectifying  system  is  subjected  to  fluctuating  volt- 


ages such  as  appear  on  axis  C  of  Fig.  7  so  long  as  both 
radio  frequencies  are  applied.  These  beat-voltages  are 
inevitably  rectified  into  a  fluctuating  or  pulsating  direct- 
current,  which  passes  through  the  telephone  windings 
and  produces  a  beat-tone  signal. 

Since  the  electrical  rectifier-telephone  combination 
is  of  great  sensitiveness,  its  application  to  heterodyne 
reception  has  made  it  possible  to  receive  selectively  over 
great  distances  with  comparatively  small  antenna  struc- 
tures. By  proper  choice  of  detector  characteristics,  the 
high  powers  of  discrimination  and  amplification  are  also 
secured  in  this  form  of  heterodyne,  and,  sincp  its  output 
is  a  varying  audio  frequency  electrical  current,  it  lends 
itself  to  combination  with  amplifiers,  electrical  tuning 
systems,  etc. 

Fig.  9  illustrates  the  soundproof  receiving  room  of 
the  Arlington  Naval  station,  where  some  interesting 
early  long  distance  work  with  the  rectifier-heterodyne 
was  done.  On  a  special  series  of  experiments,  mes- 
sages  were  copied   several   times  every  day   from  the 


*U.  S.  Patent  i  141  717,  Lee  and  Hogan. 


KIG.    g HETEKODVXE    KECEIVER     AT    THE    ARLINGTON'     RADIO    STATION 

U.  S.  S.  Salem  as  she  steamed  to  Gibraltar.  By  com- 
bining the  signals  with  local  oscillations  generated  from 
the  small  arc  shown  at  the  right  of  the  photograph,  the 
heterodyne  amplification  secured  made  it  possible  to 
read  messages  sent  by  the  ship  long  after  she  had  gone 
so  far  that  her  signals  could  not  be  understood  when 
ordinary  receivers  were  used.  Developments  of  The 
he^prodyne  since  this  work  in  191 1  have  kept  it  at  the 
head  of  the  list,  and  by  its  exceptional  sensitiveness  and 
selectivity,  it  has  made  possible  the  long-distance  com- 
munication records  which  have  been  announced  in  the 
past  few  years.  Although  the  type  of  transmitter  used 
may  vary  largely,  and  while  various  auxiliary  devices 
may  be  combined  with  the  receiver,  every  exceptional 
radio  performance  of  recent  years  has  depended  for  its 
success  upon  the  same  principle.  In  every  case  the  re- 
ceiver has  embodied  some  form  of  the  rectifying  hetero- 
dyne. 


lii)  ^omi^hilons  ©1'  Mod^^m  Iladio 


L.  W.  CHUBB  and  C.  T.  ALIA  I  I  I 


THE  year  1900  really  marked  the  beginning  of 
commercial  radio  telegraphy.  x\lthough  Mar- 
coni's experiments  with  Hertzian  waves  began 
in  1895,  it  was  not  until  1899  that  he  achieved  results 
that  indicated  unmistakably  the  commercial  utility  of 
radio  communication.  Public  interest  in  this  new  form 
of  communication  was  first  aroused  by  the  then  spec- 
tacular feat  of  transmitting  messages  by  wireless  across 
the  English  Channel.  When  Marconi  accomplished 
this  in  March  1899  he  opened  the  eyes  of  the  world  to 
the  practical  significance  of  his  heretofore  little  known 
work. 

Later  in  the  same  year  Marconi  came  to  the  United 
States  and  employed  his  wireless  S3'stem  between  a 
ship  and  the  shore  for  reporting  the  progress  of  the  In- 
ternational 3'acht  races.  This  feat  resulted  in  still  more 
publicity  for  radio  telegraphy  and  a  more  general  ap- 
preciation of  its  possibilities  for  carrying  on  communi- 
cation to  and  from  vessels  at  sea.  The  maritime  possi- 
bilities of  radio  were  further  emphasized  by  the  use  of 
radio  for  communication  between  war  vessels  during 
the  manoeuvres  of  the  British  Xavy  in  July  and  August, 
iBqo. 

These  demonstrations  of  the  practicability  of  radio 
communication  were  soon  followed  by  definite  steps 
towards  tl\e  establishment  of  regular  commercial  ship- 
to-ship  and  ship-to-shore  telegraph  service,  and  by  the 
end  of  1900  the  position  of  wireless  telegraphy  as  an 
indispensable  aid  to  navigation  and  naval  operations  was 
firmly  established. 

The  radio  station  of  1900,  however,  was  a  verj'  dif- 
ferent thing  from  the  station  of  today.  A  spark  coil 
was  used  for  transmission  and  a  coherer  for  reception. 
Continuous  wave  transmission  had  never  been  heard  of 
and  the  vacuum  tube  was  yet  to  be  invented.  The  dif- 
ference in  efficiency  and  reliability  that  but  twent)'  years 
of  progress  has  brought  about  makes  radio  communfca- 
tion  a  splendid  monument  to  the  ingenuity  of  the  manv 
able  investigators  who  have  contributed  to  the  advance- 
ment of  the  art.  Indeed  there  are  few  modern  engi- 
neering developments  in  which  so  many  men  of  high 
scientific  attainments  have  taken  part. 

In  spite  of  the  number  of  men  who  have  aided  in 
the  advancement  of  radio,  the  notable  landmarks  in  the 
progress  of  the  art  are  relatively  few  in  number.  In 
fact,  the  real  epoch-making  achievements  since  1900  are 
but  four  in  number.     These  are — 

I — Continuous  wave  transmission. 

2 — Heterodyne  reception. 

3 — The  vacuum  tube. 

4 — The  feed-back  circuit. 

While  many  other  meritorious  contributions  have 
been  made  toward  the  iirogress  of  the  radio  art,  never- 


theless, the  four  inventions  mentioned  above  represent 
the  four  great  achievements  upon  which  modern  radio 
is  founded  and  upon  which  the  future  of  the  art 
depends. 

Continuous  wave  telegraphy  was  advocated  by 
Prof.  R.  A.  Fessenden  as  early  as  1900,  although  it  was 
not  until  some  years  later  that  this  system  came  into 
commercial  use.  At  a  time  when  damped  waves  having 
a  frequency  of  2  000CX)0  cycles  per  second  or  more 
were  universally  employed,  Fessenden,  with  rare  fore- 
sight, proposed  the  use  of  sustained  waves  of  a  fre- 
quency of  100  000  cycles  or  less  produced  by  an  alter- 
nator connected  to  an  antenna  of  large  capacity.  And 
now,  some  twenty  years  later,  all  transoceanic  stations 
are  using  the  continuous  wave  system  and  relatively  low 
frequencies  advocated  by  him  in  1900,  and  many  of  the 
largest  of  these  stations  use  the  radio  frequency  alter- 
nator. While  great  credit  is  undoubtedly  due  to  the 
able  designers  who  have  produced  sucessful  radio  fre- 
quenc)'  alternators,  it  should  not  be  forgotten  that  the 
world  is  indebted  primarily  to  Professor  Fessenden  for 
the  high  frequency  alternator  system  of  radio  trans- 
mission. Not  only  was  he  the  inventor  of  the  system 
but  also  he  was  the  first  to  put  it  into  operation.  The 
first  high  frequency  alternator  used  for  radio  purposes 
was  built  for  and  put  into  operation  by  him  in  1906. 

The  development  of  continuous  wave  transmission 
was  greatly  stimulated  by  the  introduction  of  the  Poul- 
sen  arc  which  was  invented  in  1903  by  the  eminent 
Danish  engineer  whose  name  it  bears.  The  Poulsen  arc 
is  a  remarkably  simple  and  convenient  source  of  high 
frequency  for  continuous  wave  transmission  and  is  now 
made  in  sizes  ranging  from  2  to  looo  kilowatts  (input) 
capacity.  It  is  used  in  a  majority  of  the  continuous 
wave  stations  of  the  world  at  the  present  time,  although 
it  will  probably  be  superseded  in  the  future  by  the 
vacuum  tube  oscillator. 

A  special  application  of  continuous  wave  trans- 
mission that  is  rapidly  growing  in  importance  is  radio 
telephony.  For  this  particular  branch  of  radio  we  are 
also  indebted  to  Prof.  Fessenden  who,  in  1900,  pro- 
posed the  transmission  of  speech  by  means  of  continu- 
ously radiated  waves  modulated  or  varied  in  amplitude 
in  accordance  with  speech  waves.  In  the  same  year  he 
actually  transmitted  speech  for  a  distance  of  one  mile 
and  bv  1907  he  was  able  to  transmit  speech  by  this 
method  for  a  distance  of  over  one  hundred  miles. 

Although  damped  wave  or  spark  transmission  has 
done  and  is  doing  good  service,  nevertheless,  continuous 
wave  transmission  is  destined  to  be  universally  em- 
ployed in  the  future,  except  perhaps  for  emergency  calls 
at  sea.  Its  numerous  advantages  are  dealt  with  in  some 
detail  in  other  papers  in  this  issue.     In  view  of  its  great 


April,   1921 

present  importance  and  probable  universal .  use  in  the 
near  future,  it  is  believed  that  continuous  wave  trans- 
mission may  well  be  regarded  as  one  of  the  fundamental 
and  epoch-making  inventions  that  has  made  modern 
radio  possible. 

It  is  but  natural  that  the  father  of  continuous 
wave  transmission  should  also  be  the  inventor  of  the 
best  method  of  receiving  imdamped  wave  signals. 
Prof.  Fessenden's  classic  "heterodyne"  or  beat  method 
of  reception  is  fully  as  important  as  his  continuous 
wave  transmission,  for  without  heterodyne  reception, 
many  of  the  important  advantages  of  continuous  wave 
transmission  are  lost. 

The  forerunner  of  the  heterodyne  method  was  the 
system  proposed  by  Prof.  Fessenden  in  1901  when  he 
suggested  simultaneously  radiating  continuous  wave 
signals  on  two  frequencies  which  differed  from  each 
other  by  a  few  hundred  cycles.  Interference  or  "beats" 
between  these  two  waves  produced  an  audible  note  at 
the  receiving  station,  the  frequency  of  which  was  equal 
to  the  difference  in  the  frequency  of  the  two  waves  sent 
out  from  the  transmitting  station.  Some  time  later  he 
conceived  the  idea  of  generating  one  of  these  high  fre- 
(|uencies  at  the  receiving  station  and  there  combining  it 
with  the  received  signal  to  produce  beats  of  audible 
frequency.  This  is  the  method  of  reception  that  is  now 
lalled  the  heterodyne  method. 

The  heterodj'ne  reception  is  so  far  superior  to  any 
other  method  of  receiving  undamped  wave  signals  that 
its  use  may  be  regarded  as  indispensable  in  any  modern 
.station  receiving  continuous  wave  signals.  Without 
heterodyne  reception  reliable  transatlantic  radio  com- 
munication would  be  well  nigh  impossible.  Heterodyne 
reception,  therefore,  may  be  regarded  as  another  radio 
achievement  of  great  and  far  reaching  importance. 

Simultaneously  with  the  developments  discussed 
above,  many  investigators  turned  their  attention  to  the 
problem  of  improving  the  detector  employed  in  radio  re- 
ception. Innumerable  detectors  were  proposed,  each 
having  its  advocates.  Coherers,  magnetic  detectors, 
electrolytic  detectors  and  crystal  detectors  each  had 
their  day  and  eventually  succumbed  to  the  three  elec- 
trode vacuum  tube  or  "audion". 

The  history  of  the  vacuum  tube  detector  is  an  in- 
teresting one.  Early  in  the  eighties  Edison  discovered 
that  current  would  pass  between  a  hot  filament  and  a 
cold  plate  sealed  in  an  evacuated  bulb  if  the  filament 
were  connected  to  the  negative  terminal  of  a  source  of 
current.  J.  A.  Fleming  investigated  this  so-called 
"Edison  effect"  and  discovered  in  1904  that  a  vacuum 
tube  containing  a  hot  filament  and  a  cold  electrode  could 
l)e  used  as  a  radio  detector.  The  detecting  action  was 
due  to  the  well  known  rectifying  action  of  such  a  tube. 
The  Fleming  detector  nev.er  came  into  extensive  com- 
mercial use.  Its  chief  claim  to  distinction  is  the  fact 
that  it  Was  the  forerunner  of  the  three  electrode  tube 
detector. 

In  placing  a  grid  between  the  plate  and  filament  of 
a  Fleming  detector,  DeForest  did  far  more  than  merely 


THE   ELECTRIC  JOURX.IL 


secure  an  improved  detector.  He  produced  a  cTevice 
that  would  amplify,  that  is,  it  would  release  energy 
from  a  local  source  in  greater  amount  than  the  energy' 
of  the  received  signal.  It  is  due  to  this  amplifying 
action  that  the  versatile  three  electrode  tube  is  able  to 
accomplish  such  remarkable  results  in  the  many  appli- 
cations that  have  been  found  for  it. 

For  some  years  after  its  invention,  the  audion  de- 
tector was  of  but  little  importance  commercially.  It 
was  not  more  than  twice  as  sensitive  as  the  best  crystal 
or  electrolytic  detectors  and  this  slight  gain  in  sensi- 
tivity was  hardly  sufficient  to  bring  it  into  very  exten- 
si\e  use.  It  was  not  until  after  Armstrong  discovered 
that  certain  circuit  connections  enabled  a  three  elec- 
trode tube  to  give  signals  many  thousand  times  as  strong 
as  any  other  known  detector  that  the  vacuum  tube  began 
to  assume  its  present  great  importance  in  the  radio  field. 
Because  of  its  present  importance  and  overwhelming 
potentialities  for  the  future  we  inay  regard  the  three 
electrode  tube  as  an  invention  that  is  second  to  none  in 
the  part  it  has  played  in  the  development  of  modern 
ratio. 

Armstrong's  discovery  of  the  feed-back  circuit  that 
has  assumed  such  great  importance  in  our  present  dav 
radio  practice  dates  back  to  1912.  Coincident  with  the 
discovery  of  the  enormous  amplification  possible  with 
the  feed-back  circuit,  he  learned  that  proper  adjustment 
of  the  circuit  caused  the  three-electrode  lube  to  produce 
continuous  oscillations  of  radio  frequency.  He  also 
found  that,  when  generating  .such  oscillations,  the  tube 
could  be  used  to  receive  undamped  waves  by  the  hetero- 
dyne or  beat  method. 

The  generation  of  continuous  oscillations  by  mean."! 
of  the  feed-back  circuit  is  now  one  of  the  most  valuable 
applications  of  the  three-electrode  tube.  As  a  local 
source  of  radio  frequency  for  heterodyne  reception  it 
has  no  rival.  The  so-called  "self-heterodyne"  method 
of  reception,  in  which  the  same  tube  is  used  as  an  oscil- 
lation generator  and  as  a  detector,  is  perhaps  the  most 
widely  used  method  of  receiving  continuous  wave 
signals. 

For  radio  telephone  transmission  the  vacuum  tube 
oscillator  is  almost  universally  employed.  In  fact  the 
present  success  of  radio  telephony  may  be  said  to  be 
largely  due  to  the  feed-back  oscillator,  whose  simplicity 
and  ease  of  control  make  it  peculiarly  adapted  to  this 
service. 

In  the  field  of  radio  telegraph  transmission  also  the 
vacuum  tube  oscillator  seems  destined  to  play  an  impor- 
tant part.  As  continuous  wave  transmission  supersedes 
the  spark  system  for  short  and  medium  range  telegraph 
service,  we  shall  find  that  the  feed-back  oscillator  will 
be  largely  relied  upon  as  a  source  of  radio  frequency 
for  transmission  purposes.  Eventually  the  vacuum 
tube  oscillator  may  even  find  its  place  in  the  high  power 
transoceanic  stations  as  a  substitute  for  the  alternator 
or  Poulsen  arc.  Already  one  European  station  is  feed- 
ing 75  kilowatts  into  its  antenna  from  tube  oscillators, 
using  a  batter)'  of  ten  tubes,  each  having  an  output  of 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


7.5  kilowatts.  Even  larger  units  have  been  built  ex- 
perimentally in  this  country  and  it  will  probably  not  be 
many  years  before  we  shall  see  vacuum  tube  oscillators 
having  an  output  of  50  kilowatts  and  more. 

The  changes  in  radio  practice  brought  about  by  the 
feed-back  circuit  are  almost  revolutionary  in  character. 
In  the  future  it  may  be  responsible  for  even  more  start- 
ling changes.  In  fact  the  feed-back  circuit  is  at  least 
equal  in  importance  to  the  three-electrode  tube  whose 
value  in  the  radio  art  it  so  greatly  enhances.  Arm- 
strong's discovery,  therefore,  deserves  a  vtry  high  rank 
among  the  radio  achievements  of  the  present  century. 


There  are  many  radio  developments  other  than 
those  discussed  above  that  merit  consideration  in  any 
paper  that  purported  to  be  a  complete  history  of  the  art. 
This  article,  however,  merely  attempts  to  set  forth  the 
fundamental  discoveries  that  are  largely  responsible  for 
the  amazing  progress  in  radio  communication  since  the 
days  when  it  first  became  a  commercial  possibility.  This 
progress  was  largely  based  on  the  change  from  the  old 
spark  system  to  the  modern,  continuous  wave  trans- 
mission with  heterodyne  reception,  and  on  the  introduc-' 
tion  of  the  two  most  valuable  tools  of  the  radio  engi- 
neer, the  three-electrode  tube  and  the  feed-back  circuit. 


Stntic  Fi'o^(((Oiu^y  T)0((x)]oi>s 


J.  F.  PETERS 

Transformer  Engineering  Dept., 
^stinghouse  Electric  &  Mfg.  Company 


IN  high  power  radio  sending  stations,  where 
the  power  is  supplied  by  a  high  frequency  alternator, 
the  sending  frequency  can  be  generated  directly,  or 
the  required  amount  of  power  can  be  generated  at  a 
lower  frequency,  and  then  the  frequency  increased  to 
the  desired  value  by  means  of  frequency  multipliers. 

The  difficulties  of  constructing  an  alternator  for, 
say,  15  000  cycles,  are  much  less  than  those  involved  in 
constructing  one  for  30  000  to  60  000  cycles.  This  fact 
has  prompted  a  careful  study  of  frequency  multipliers 
and  resulted  in  their  use  in  several  of  the  high  power 
radio  stations.  Some  stations  multiply  to  the  extent  of 
doubling  three  times,  that  is,  they  generate  at  6000 
cycles  and  double  to  12000,  24000  or  48000  cycles. 

The  possibility  of  using  the  variation  in  permea- 
bility of  iron  for  frequency  multiplying  was  suggested 


FIG.    1 — HIGH   FREQUENCY  DOUBLER 

Employing  two   identical   transformers,   each  having   three 
windings. 

by  Epstein,  in  1902.  The  subject,  however,  was  not 
given  much  study  until  191 1,  when  Joly  and  Vallauri 
developed  several  types  of  multipliers.  There  have  been 
several  satisfactory  schemes  devised  for  multiplying 
frequencies  by  means  of  saturated  iron  cores,  but  only 
the  one  that,  in  the  writer's  opinion,  is  the  most 
economical  will  be  discussed  here. 

Consider  two  identical  transformers,  each  having 
three  windings  connected  as  shown  in  Fig.  i.  The 
primaries,  Pj  and  Po  are  connected  in  series,  and  their 
outer  leads  are  connected  to  an  alternating-current 
generator.  The  secondaries,  S^  and  5,  and  third  wind- 
ings, D^  and  D^,  are  connected  in  series  opposition.     If 


an  alternating  voltage  is  impressed  across  the  primary 
terminals,  there  will  be  identical  magnetic  flu.x  varia- 
tions in  the  two  cores,  with  the  result  that  no  voltage 
will  appear  across  the  secondary  terminals  because  this 
winding  is  connected  in  opposition.  Now  suppose  a 
direct  current  is  passed  through  windings  D^  and  D.-., 
producing  a  magnetic  flux  in  the  two  cores  in  the  direc- 
tions indicated  by  the  dotted  arrows.  Under  these 
conditions,  when  an  alternating  voltage  is  applied  to  the 
primary  terminals,  the  magnetic  flux  variations  in  the 
two  cores  will  not  be  identical,  as  the  alternating  flux 
will  add  to  the  direct-current  flux  in  one  core  and  sub- 
tract from  it  in  the  other.  It  is  well  known  that  the 
required  number  of  ampere-turns,  magnetizing  current 


A •      \  /  /A| 

'  *■   \         ^^       7         X 


FIG.    2 — FLUX    W.WES    OV    HIGH    FKEQUEKCV    DOUIiLER 

per  unit  of  flux,  is  much  greater  at  high  flux 
densities  than  it  is  for  low  flux  densities.  The 
alternating-current  ampere-turns  for  the  two  cores 
are  identical,  being  in  series,  therefore  the  in- 
crease in  flux  in  core  /,  where  the  alternating  and  di- 
rect currents  add,  will  be  less*  than  the  decrease  in  flux 
in  unit  2  where  they  subtract ;  consequently  the  flux 
variations  in  the  two  units  will  be  diflferent,  resulting  in 
there  being  a  resultant  voltage  across  the  combined 
secondaries. 


April,  1921 


THE  ELECTRIC  JOURNAL 


123 


Let  us  investigate  the  voltage  and  flux  conditions 
when  the  direct-current  flux  has  completely  saturated 
the  cores.  In  Fig.  2,  A-A^  is  the  zero  line  for  primar)' 
voltage  and  flux;  E  represents  the  primary  impressed 
voltage  Fp  represents  the  primary  flux ;  B-B^  is  the  zero 
line  for  the  total  fluxes  in  both  cores ;  C-C^  is  the  direct- 
current  flux  in  transformer  /,  measured  above  B-B^, 
and  Z)-Z?i  is  the  direct-current  flux  for  transformer  2, 
measured  below  B-B.^.  The  primary  impressed  voltage 
is  assumed  to  have  a  sine  wave  E.  Its  resultant  flux  Fp 
will,  therefore,  be  a  sine  wave  90  degrees  later  in  time 
phase.  The  primarj'  voltage  has  a  maximum  when  its 
flux  is  zero,  as  indicated  by  point  S.  Starting  from  this 
point,  for  the  next  one-half  cycle,  the  primary  current 
will  not  materially  increase  the  flux  in  transformer  /,  as 
this  magnetic  circuit  is  already  saturated,  but  will  pro- 
duce a  large  decrease  in  flux  in  transformer  2,  as  is  in- 
dicated between  points  a  and  h.  For  the  next  half  cycle, 
the  conditions  in  the  two  cores  will  have  reversed,  as  in- 
dicated between  points  h  and  c. 

The  voltage  induced  in  the  secondary  windings  due 


/' 

/ 

/ 

/ 

/ 

J 

/ 

B 

t> 

d 

>> 

jf 

D 

) 

V 

1 
)i^    0 

^ 

' 

^ 

^ 

° 

/ 

2 

1° 

npere 

Tun 

« 

« 

8 

» 

/< 

7 

^ 

r 

: 

FIG.   3 — EFFECT  OF   S.\TUR.\TED   CORE   ON    SHAPE  OF  VOLT.\GE    WAVE 

to  the  change  in  magnetic  flux  in  the  two  cores  is  shown 
in  the  lower  part  of  Fig.  2,  with  £-£,  as  zero  line.  Be- 
tween the  points  a  and  h  there  is  no  change  in  flux  in 
transformer  i,  but  there  is  a  change  in  transformer  2. 
The  voltage  due  to  this  change  is  shown  dotted.  For 
the  next  half  cycle,  between  points  b  and  c,  there  is  a 
change  in  flux  in  transformer  i  but  not  in  transformer  2. 
The  voltage  due  to  this  change  in  flux  is  shown  by  a  full 
line  curve.  This  full  line  cun'e  matches  with  the  dotted 
curve  at  b,  the  two  forming  a  continuous  curve  of  volt- 
age at  double  frequency.  This  double  frequency  volt- 
age also  appears  across  the  direct-current  winding,  and 
in  order  to  prevent  a  large  double  frequency  current 
from  flowing  in  the  direct-current  winding,  an  induct- 
ance, indicated  as  L  in  Fig.  i  must  be  inserted  in  this 
winding. 

One  or  the  other,  or  both  cores,  are  highly  satu- 
rated at  all  times,  and  the  load  currents  in  both  primary 
and  secondary  windings  must  flow   through   the  satu- 


rated inductance  of  the  transformers.  In  order  to  off- 
set this  inductance,  it  is  necessary  to  connect  electro- 
static condensers  in  both  primary  and  secondary  cir- 
cuits, indicated  as  C^  and  C.  in  Fig.  /.  These  con- 
densers must  store  a  large  kv-a,  several  times  the  kw 
handled  by  the  doubler.  Large  kv-a's  can  be  economi- 
cally handled  In-  electrostatic  condensers  only  at  high 
frequencies.  It  is  this  large  kv-a  of  condensers  re- 
quired that  makes  doubling  commercial  frequencies  (25 
and  60  cycles)  impractical. 

The  analysis  represented  by  Fig.  2  indicates  that,  if 
the  primary  and  secondary  windings  have  the  same 
number  of  turns,  their  voltages  will  be  the  same.  This, 
however,  is  not  quite  correct.  The  correct  ratio  of 
voltages  can  easily  be  determined,  as  outlined  in  con- 
nection with  Fig.  3,  in  which  B  is  the  saturation  curve 
of  the  cores.  The  absissas  represent  ampere-turns,  and 
the  ordinates  flux  density.  Assume  that  each  trans- 
former has  a  direct-current  excitation  of  200  ampere- 


FIG.   4 — HIGH    FKEQUEXCV    DOUBI.ER    REMOTCD    FRO.M    TANK 

turns.  Then  with  no  alteniating-current  excitation,  the 
cores  will  be  excited  to  the  point  o,  due  to  the  direct- 
current  ampere-turns.  Also  suppose  that  the  maximum 
instantaneous  alternating-current  ampere-turns  will  be 
400,  then  as  the  alternating-current  ampere-turns  start 
from  zero,  the  two  cores  will  each  start  at  a.  One  will 
increase  to  the  sum  of  the  alternating-current  and  di- 
rect-current turns,  or  600,  shown  at  b,  while  the  other 
will  decrease  to  the  difference  between  the  alternating- 
current  and  direct-current  turns  or  -  200,  as  indicated  at 
/.  The  flux  in  the  one  core  will  have  changed  from  a 
to  /,  or  a  value  cf,  while  the  other  core  will  have 
changed  from  a  to  h,  or  a  value  bd.  The  total  variation 
affecting  the  primary  voltage  will  then  be  cf  -)-  bd, 
while  the  variation  producing  the  secondary  voltage 
will  be  cf  —  bd  =^  be.  Thus  the  secondary  voltage  is 
less  than  the  primary  by  twice  bd. 


C©ntJM3©p^  Wavo  lladi®  CominPTilcadoii 


D.  G.  LITTLE 

Radio  Engineer, 
Westingliouse  Electric  &  Mfg.  Company 


THE  USE  of  continuous  or  undamped  waves  in 
radio  communication  is  rapidly  becoming  mii- 
versal  to  the  exclusion  of  damped  wave  or  spark- 
systems.  It  is  highly  significant  that  the  Preliminarj- 
International  Communications  Conference  which  con- 
vened at  Washington  in  October  1920,  recommended 
legislation  which  will  confine  the  use  of  damped  wave 
equipment  to  low  power  ship  emergency  installations 
and  amateur  sets  operating  on  short  wave  lengths.  In 
all  probability,  the  next  five  years  will  witness  the  re- 
placement of  practically  all  existing  spark  apparatus 
with  continuous  wave  equipment.  It  may  not  be  too 
much  to  predict  that  even  amateur  communication  on 
wave  lengths  as  short  as  200  meters,  where  beat  note 
reception  offers  the  greatest  difficulties,  will  become 
largely  continuous  wave,  reception  of  these  short  wave 
lengths  having  been  made  possible  by  means  of  the 
Armstrong  superaudodyne  method. 

The  reasons  for  the  discontinuance  of  spark  appar- 
atus in  favor  of  continuous  wave  equipment  are  numer- 
ous. In  the  first  place  the  increasing  use  of  radio  com- 
munication makes  interference  between  stations  a  seri- 
ous problem.  The  wave  lengths  used  in  radio  communi- 
cation lie  between  150  and  25  000  meters  corresponding 
to  frequencies  of  2  000  000  to  12  000  cycles  per  second*. 
The  longer  wave  lengths,  from  10  000  meters  upwards, 
are  employed  for  transoceanic  work  and  the  shorter  in 
ship  to  ship,  ship  to  shore,  and  land  station  operation. 
It  is  impossible  to  operate  two  or  more  damped  wave 
stations  in  the  same  locality  on  wave  lengths  closer 
than  three  percent  to  each  other  without  having  inter 
ference,  even  if  these  stations  have  decrements  as  low 
as  0.06  which  is  an  extremely  sharp  spark  wave.  A 
receiving  station  attempting  to  copy  one  of  these  trans- 
mitting stations  could  not  help  hearing  and  being  inter- 
fered with  by  others.  The  number  of  damped  wave 
transmitters  it  is  possible  to  work  in  a  given  locality  is 
thus  limited  to  a  small  number.  The  wave  lengths  of 
continuous  wave  transmitters  may  be  adjusted  to  within 
one  percent  of  each  other  and  yet  cause  no  interference 
at  a  distant  receiver.  With  further  refinements  in  re- 
ceiving apparatus,  such  as  tuned  audio-frequency  cir- 
cuits, even  closer  wave  lengths  may  be  used.  It  is 
possible  to  handle  at  least  three  times  as  much  traffic  in 
a  given  area  with  continuous  wave  apparatus  as  with 
damped  wave  transmitters. 

The  heterodyne   or  beat  method  of  reception  in- 

*For  those  not  familiar  with  radio  nomenclature  it  may  bo 
said  that  the  term  "wave  length",  is  generally  used  in  place  of 
"frequency''  the  relation  between  the  two  being: — ivave  lencfth 
^       SXw" 
frequency 


vented  by  Professor  R.  A.  Fessenden,  in  1905,  when 
employed  in  connection  with  a  vacuum  tube  oscillator 
and  detector,  is  by  far  the  simplest  and  most  sensitive 
means  of  receiving  continuous  wave  signals.  The 
heterodyne  system  consists  simply  in  combining  the  in- 
coming radio  frequency  waves  with  a  current  of  a  fre- 
quency differing  from  the  incoming  signal  by  an 
audible  frequency  amount,  the  result  after  rectification 
being  the  audio  frequency.  By  adjusting  the  frequency 
of  the  local  oscillator  at  the  receiver  it  is  easily  possible 
to  make  the  beat  any  desirable  frequency,  thus  allowing 
the  operator  to  utilize  the  most  sensitive  frequency  for 
the  telephone  receivers,  tuned  amplifier  or  recorder. 

In  addition  to  lessened  interference  and  beat  note 
reception,  the  lower  voltages  on  continuous  wave  trans- 


FIH.    I — 2   K\V   POULSEN   ARC  TRANSMITTER 

Built   for  the   United   States   Navy  by   the   Federal   Tele- 
graph Company. 

mitting  apparatus  should  be  taken  into  consideration. 
For  example  a  three  kw,  500  cycle  spark  transmitter 
operating  at  1000  meters  wave  length  on  an  antenna  of 
o.ooi  micro  farads  capacity  and  six  ohms  resistance 
might  put  1000  watts  into  the  antenna.  The  instan- 
taneous maximum  voltage  on  the  antenna  would  be 
approximately  45000  volts.  A  continuous  wave  set 
with  the  same  power  output  would  give  a  maxi- 
mum antenna  voltage  of  only  10  000  volts ;  which  is  a 
big  advantage  as  regards  antenna  insulation,  as  well  as 
on  the  set  itself.  This  is  obviously  the  case  since,  with 
a  spark  set,  the  antenna  and  oscillating  circuits  have 
power  in  them  for  only  short  intervals  of  time,  sepa- 
rated by  relatively  long  periods  of  inaction,  while  in  the 
continuous  wave  system  power  is  in  the  oscillating  cir- 
cuits continuously.     There  are  other  advantages  to  con- 


April,   1 92 1 


THE   ELECTRIC  JOURNAL 


imuous  wave  apparatu?,  not  the  least  of  which  is  the 
lack  of  noise,  especially  in  ship  installations,  where  the 
noisy  spark  has  been  so  disturbing  to  passengers. 

On  the  other  hand,  the  most  important  advantage 
of  continuous  wave  systems,  namely  less  interference, 
becomes  a  disadvantage  when  it  is  desired  to  broadcast 
or  to  send  ouf  distress  signals.  The  sharpness  of  the 
tuning  makes  continuous  wave  signals  more  difficult  to 
pick  up  than  spark  signals.  This  disadvantage  will 
gradually  disappear,  however,  as  continuous  wave  sets 
working  on  short  wave  lengths,  say  300  to  2000  meters, 
come  into  general  use. 

The  pioneer  inventor  in  the  field  of  continuous 
wave  radio  communications  is  Professor  Fessenden. 
As  early  as  1901,  he  pro- 
posed the  use  of  continu- 
ous or  sustained  waves  of 
a  relatively  low  frequency 
of  100  000  cycles  or  less, 
generated  by  radio  fre- 
quency alternators.  At  the 
same  time  Prof.  Fessenden 
pointed  out  the  desirability 
of  employing  large  antenna 
for  long  distance  work  in 
place  of  the  relatively  small 
high  antenna  in  use  at  that 
time.  Prof.  Fessenden 
also  noted  that  radio  speech 
transmission  could  best  be 
accomplished  by  modiflat- 
ing  the  output  of  a  source 
of  continuous  waves.  It  is 
remarkable  to  note  how 
closely  the  radio  systems  of 
today  follow  the  lines  sug- 
gested by  Prof.  Fessenden 
twenty  years  ago. 


the  period  from  1900  to  1903,  W.  Duddell  and  V.  Poul- 
sen  developed  the  arc  to  the  point  where  radio  fre- 
quencies could  be  generated.  Poulsen  enclosed  the  arc 
in  a  hydrocarbon  atmosphere,  made  the  anode  of  copper 
water-cooled  and  placed  the  arc  in  a  strong  transverse 
magnetic  field*. 

Arc  converters  are  now  built  in  sizes  of  2  to  1500 
kw  input  at  400  to  1250  volts  direct  current  with  effi- 
ciencies of  20  to  30  percent.  Signaling  has  generally 
been  accomplished  by  short-circuiting  a  part  of  the  in- 
ductance in  the  antenna  circuit,  thus  changing  the  wave 
length  transmitted  and  the  pitch  of  the  signal  at  the  re- 
ceiv'ng  station.  This  compensating  or  "back  wave" 
method  has  been  prohibited  in  the  recommendations  of 


FIG.    2 — 1000  KW   ARC  CONVERTER 

Built  for  the  United  States  Navy.     Two  of  these  converters  were  installed  at  the  Lafayette 
Radio  Station  near  Bordeaux,  France. 


Continuous  or  undamped  wave  generators  of  radio 
frequencies  may  be  divided  into  three  classes;  first  the 
arc  generator  or  arc  converter,  second  the  high  fre- 
cjuency  alternator  and  third  the  hot  cathode  vacuum 
tube.  Other  systems  operating  upon  spark  principles 
but  generating  waves  of  very  slight  decrement  employ 
the  timed  spark  and  the  Chaffee  gap. 

AKC  GENERATORS 

It  was  early  discovered  by  Elihu  Thomson  that  an 
arc  between  carbon  electrodes  would  "sing"  when 
shunted  by  a  capacity  and  inductance  of  proper  values. 
On  account  of  its  falling  current-voltage  characteristic, 
the  arc  generated  oscillations  in  a  circuit  consisting  of 
capacity,  inductance  and  arc  which,  with  the  constants 
used,  were  generally  of  an  audible  frequency,  hence 
the  name  "singing  arc".  It  is  doubtful,  however,  if  the 
arc  between  carbon  electrodes  in  air  employed  by 
Thomson  would  have  been  capable  of  generating  oscil- 
lations of  much  higher  than  audio  frequencies.     During 


the  Preliminary  International  Comntunications  Confer- 
ence as  causing  unnecessary  interference.  The  most 
successful  method  of  sending  a  single  frequency  is  that 
invented  by  Lt.  W.  A.  Eaton  of  the  United  States  Navy, 
in  which  the  arc  load  is  shifted  alternately  from  the 
antenna  to  a  phantom  load  circuit.  For  telephone  trans- 
mission, the  arc  may  be  modulated  by  placing  a  micro- 
phone in  the  antenna  circuit,  or  in  a  circuit  coupled  to 
the  antenna  circuit.  It  is  also  possible  to  re-ig^ite  the 
arc  for  each  dot  or  dash  signal  by  passing  a  spark  be- 
tween the  electrodes.  Fig.  i  shows  a  typical  two  kilo- 
watt converter  with  motor-generator  set  and  control 
equipment  such  as  are  used  by  the  U.  S.  Navy  for  ship 
mstallations.  The  largest  arc  converters  now  in  opera- 
tion are  the  two  1000  kw  units  installed  at  the  Lafayette 
Radio  Station  near  Bordeaux,  France. 


*These  improvements  cover  substantially  the  arc  converter 
or  arc  generator  as  built  at  present  by  the  Federal  Telegraph 
Company  and  the  Westinghouse  Electric  &  Mfg.  Company, 
under  Poulsen  patents  in  the  United  States. 


126 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


HIGH   FREQUENCY  ALTERNATORS 

The  first  alternator  designed  to  give  a  frequency 
higher  than  the  usual  60  to  133  cycles  was  built  by 
Elihu  Thomson  and  Nikola  Tesla  in  1890.  This  ma- 
chine was  not  for  radio  purposes,  however,  but  for  arc 
lighting,  there  being  considerable  objection  at  that  time 
to  the  hum  produced  by  the  low  frequency  arc.  A  fre- 
quency of  100  000  cycles  per  second  or  near  the  upper 
limit  of  audibility  was  claimed  for  the  machine. 

During  1902,  B.  G.  Lamme,  of  the  Westinghouse 
Company,  designed  a  high  frequency  alternator.  This 
machine  was  of  the  double  crown  inductor  type  similar 
to  modern  high  frequency  alternators  of  today.  This 
alternator  was  used  in  experiments  on  wired  wireless 
and  multiplex  telephony  by  M.  Le  Blanc  in  France. 

In  1900,  Prof.  Fessenden,  then  in  the  employ  of 
the  United  States  Government,  asked  Dr.  C.  P.  Stein- 
metz  of  the  General  Electric  Company  if  it  would  be 


FIG.    3 — 200  KW  HIGH  FREQUENCi-  .M.TERNATOR 

With  600  hp  driving  motor. 

possible  to  build  a  Mordey  induction-type  alternator  for 
a  frequency  of  100  000  cycles.  Not  favoring  this  type 
of  machine  for  high  frequencies,  Dr.  Steinmetz  sug- 
gested awaiting  the  results  from  a  10  000  cycle,  two  kw 
alternator  which  they  were  building.  This  machine 
was  completed  in  the  fall  of  1902  and  used  experiment- 
ally for  radio  telephony  by  Prof.  Fessenden.  In  1904 
the  question  of  higher  frequency  alternators  was  taken 
up  again  with  the  General  Electric  Company,  who 
agreed  to  build  a  100  000  cycle  machine  of  the  induction 
type  proposed  by  Prof.  Fessenden.  The  development 
of  the  alternator  was  started  by  Mr.  Ernest  Berg,  but 
this  work  was  turned  over  to  Mr.  E.  F.  W.  Alexander- 
son,  who  continued  working  on  this  machine  in  connec- 
tion with  Prof.  Fessenden  until  the  summer  of  1906, 
when  the  machine  was  tested  and  shipped  to  the  Brant 
Rock  station  of  the  National  Electric  Signaling  Com- 
pany. Here  it  was  used  for  continuous  wave  telegraphy 
and  modulated  continuous  wave  telephony.  Prof. 
Fessenden  himself  subsequently  built  a  doHble  arma- 
ture    alternator     ha\ing      130     teeth      in     the     field 


and  300  coils  on  each  armature.  This  unit  was  direct- 
connected  to  a  De  Laval  steam  turbine  and  generated 
2.5  kw  at  225  volts  and  72000  cycles  per  second.^  In 
1908  Prof.  Fessenden  transmitted  speech  from  Brant 
Rock,  Mass.  to  New  York  City,  a  distance  of  290  miles, 
by  means  of  a  high  frequency  alternator.  The  power 
in  the  antenna  was  200  watts  and  the  carrier  frequency 
was  100  000  cycles  per  second. 

A  modern  type  of  high  frequency  alternator,  ex- 
tensively used  by  the  Radio  Corporation  of  America  for 
long  distance  communication*  is  shown  in  Fig.  3.  This 
is  an  inductor  machine  having  stationary  field  and 
armature  windings,  with  a  toothed  disc  rotating  in  the 
magnetic  field.  This  type  of  alternator  has  been  manu- 
factured in  sizes  up  to  200  kw  for  frequencies  varying 
from  100  000  cycles  in  the  two  kw  size  up  to  25  000 
cycles  in  the  200  kw  machine.  Efficiencies  of  20  to  40 
percent  are  claimed.  A  magnetic  amplifier,  controlling 
the  field  circuit  of  this  high  fre- 
quency alternator,  has  been  de- 
veloped, by  the  aid  of  which 
speech  may  be  transmitted. 

A  Latour  high  frequency 
alternator,  which  is  similar  in 
construction  to  the  early  design 
by  ]\Ir.  Lamme,  is  installed  at 
the  Lafayette  radio  station,  in 
addition  to  the  two  1000  kw  arc 
converters.  A  high  frequency 
alternator  of  the  same  general 
type  but  "of  somewhat  dift'erent 
construction  has  been  developed 
by  the  Westinghouse  Company. 
The  German  station  at  Eilviese 
is  equipped  with  an  alternator 
of  the  reflection  type  built  by 
Goldschmidt. 

VACUUM  TUBES 

The  use  of  a  hot  cathode  rectifier  employing  the 
so-called  "Edison  effect"  as  a  radio  detector  was  dis- 
covered in  1904  by  Dr.  J.  A.  Fleming.  Dr.  Fleming's 
valve  was  simply  a  rectifier  having  a  heated  filament  or 
cathode  and  a  plate  or  anode  placed  in  an  evacuated 
bulb.  It  was  used  as  a  detector  in  receiving  and  was  a 
great  improvement  as  regards  stability  of  adjustment 
over  the  detectors  in  use  at  that  time.  At  a  somewhat 
later  date  Dr.  Lee  De  Forest  made  a  much  superior  de- 
tector by  placing  a  grid  or  control  member  between  the 
filament  and  plate  in  the  bulb.  This  vacuum  tube  or 
j'udion  valve,  as  it  was  called,  was  placed  upon  the 
market  previous  to  1907  and  was  the  forerunner  of  the 
three  electrode  vacuum  tube  of  today. 

It  remained  for  Armstrong  in  1912  to  invent  the 
feed-back  or  regenerative  circuit  by  means  of  which  the 
three  electrode  vacuum  tube  may  be  made  to  amplify  to 
an  enormous  degree  and  to  generate  alternating  cur- 


*This  machine   is   described   fully   in   the   General  Electric 
Rcviczt;  October  1920,  p.  813. 


April,  1921 


THE  ELECTRIC  JOURNAL 


127 


rents  of  almost  any  desired  frequency.  The  tubes  used 
by  Armstrong  were  of  the  high  vacuum  or  "hard" 
variety  in  contrast  to  the  low  vacuum  or  soft  audion 


FIG.   4 — FRENCH    E-I3    CONTINUOUS     WAVE    VACUUM     TUBE    TRANS- 
MITTING  AND  RECEIVING   SET 

valves  made  by  Dr.  De  Forest.  The  soft  tube  is  a  more 
sensitive  detector  but  it  was  noted  by  Armstrong  that 
only  hard  tubes  could  be  used  as  power  oscillators  or 
could  be  depended  upon  as  amplifiers. 

Armstrong's  contribu- 
tions to  the  art  of  continumi- 
wave  radio  communicate  mi 
are  thus  of  the  greatest  m 
portance.  First,  his  invci 
tion  of  the  feed-back  circuit 
is  fundamental  to  the  opeiM- 
tion  of  vacuum  tube  trrjii- 
mitters.  Second,  the  reccp 
tion  of  continuous  wave^  K 
the  heterodyne  method  i- 
greatly  simplified  by  using  a 
vacuum  tube  as  a  local  oscil- 
lator \\\i\\  the  receiver,  in 
place  of  a  small  arc  or  gen- 
erator or,  in  the  case  of  short 
waves,  by  Armstrong's  self- 
heterodyne  or  oscillating  de- 
tector. For  extremely  short 
waves  the  Armstrong  super- 
heterodyne detector  and  am- 
plifier is  a  practical  necessity. 

In  1913  the  American 
Telephone  &  Telegraph  Com- 
pany   and    Western    Electric 

Company  started  development  of  three  electrode  tubes 
as  amplifiers  for  telephone  repeater  work  and  oscillators 
to  generate  the  high  frequency  carrier  wave  for  multi- 


plex telephony.  Some  very  creditable  work  was  accom- 
I)lished  by  tJie  engineers  of  these  companies  so  that  by 
1917  high  vacuum  tubes,  that  could  be  used  to  generate 
small  amounts  of  radio  frequency  power,  were  avail- 
able. 

Soon  after  the  outbreak  of  the  war  in  1914,  France 
developed  and  put  into  the  field  an  innovation  in  mili- 
tary radio  apparatus,  namely  continuous  wave  transmit- 
ting and  receiving  sets  using  three  electrode  tubes  as 
oscillators  for  transmitting  and  the  same  type  of  tube  as 
self-heterodyne  or  oscillating  detector  and  audio  fre- 
quency amplifier  for  receiving.  Fig.  4  shows  a  late 
ty[)e  of  French  vacuum  tube  transmitter  and  receiver. 
These  sets  were  small,  compact  and  light  in  weight,  yeT 
it  was  possible  to  establish  telegraphic  communication 
of  from  50  to  100  miles  with  only  5  to  10  watts  output 
on  low  portable  field  antennae.  This  illustrates  the 
seemingly  remarkable  carr>ing  power  of  continuous 
wave  transmission,  due  to  the  fact  that  all  the  energy 
radiated  at  the  transmitter  is  on  one  wave  length  only, 
the  absolutely  pure  musical  tone  received  by  means  of 
the  heterodyne,  adjustable  in  pitch  at  the  receiver,  and 
the  increased  sensitiveness  of  the  detector  when  using 
the  heterodyne  method. 

The  British  army  brought  out  similar  continuous 
wave  apparatus  shortly  afterward,  using  at  first  the 
standard  French  vacuum  tubes,  and  later  manufactur- 
ing their  own  tubes.  With  the  entry  of  the  United 
States  into  the  war,  development  of  vacuum  tube  tele- 
graph and  telephone, sets  was  immediately  started  by  the 


FIG.    S- 


SIGNAI.   CORPS    CONTINUOUS    WAVE   RADIO   TRANSMITTER  AND  RECEIVER  TYPE   S  C  R  79 

Signal  Cor[is  and  the  Navy.  The  Signal  Corps  sets 
were  designed  for  tubes  manufactured  by  the  Western 
Electric    Company.       Fig.    5    shows    a    Signal    Corps 


128 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


continuous  wave  transmitter  and  receiver  (Type  SCR 
79).  Th^  Navy  seemed  to  favor  tubes  developed  by  the 
General  Electric  Company.  Both  of  these  companies 
now  have  standard  tubes  of  5,  50  and  250  watts.  When 
greater  power  is  desired  it  is  customary  to  connect  one 
or  more  tubes  as  master  oscillators  or  exciters  and  to 
amplify  the  output  of  these  tubes  by  banks  of  similar 
tubes  in  parallel,  having  their  grids  connected  to  the  out- 
put of  the  exciters  and  their  plates  to  the  output  circuit 
of  the  set.  Fig.  6  illustrates  a  set  of  six  kilowatt  input 
built  by  the  English  Marconi  Company.  The  high  volt- 
age direct  current  for  the  plates  is  obtained  from  alter- 
nating current  by  means  of  the  four  rectifying  tubes, 
shown  at  the  right.  Two  control  and  two  modulating 
valves  for  telephony  are  mounted  between  the  rectifying 
tubes  and  the  six  oscillator  tubes  at  the  left.  The 
antenna  loading  inductance  is  mounted  separately. 

The  relative  advantages  and  disadvantages  of  the 
three  types  of  continuous  wave  generators,  the  arc,  the 
alternator  and  the  vacuum  tube  are  as  follows : — 


FIG.   6 — SIX  KW  M.\RCONI  CONTIOL'OCS  W.WE  TR.VNSMITTEK 

The  advantages  of  the  arc  lie  chiefly  in  the  low  lirst 
cost,  rugged  construction  and  low  cost  of  operation  and 
maintenance.  The  wave  length  generated  may  be  easily 
adjusted  by  varying  the  antenna  loading  inductance  or, 
for  short  wave  lengths,  the  series  antenna  condenser. 
With  the  present  design  of  arcs,  however,  wave  lengths 
shorter  than  1000  meters,  (300000  cycles)  are  not 
commercially  practical.  Also  arc  transmitters  radiate 
harmonics  of  the  fundamental  frequency  which  cause 
much  interference  at  nearby  receiving  stations.  Despite 
these  disadvantages,  at  least  90  percent  of  all  the  con- 
tinuous wave  stations  are  now  equipped  with  arcs.  They 
are  standard  equipment  on  the  larger  ships  and  in  the 
land  stations  of  the  United  States  Navy. 

The  high  frequency  alternator  system  has  the  ad- 
vantage of  emitting  a  practically  pure  continuous  wave 
without  harmonics,  easily  controlled  by  means  of  the 
field  current  of  the  generator.  The  mechanical  details 
have  been  worked  out  so  that  but  little  more  attention  is 
required  than  for  low-frequency  alternators.  While 
alternators  may  be  designed  to  give  any  frequency  less 


than  about  200  000  cycles,  a  given  machine  cannot  gen- 
erate a  frequency  materially  different  from  that  for 
which  it  was  designed.  This  is  fundamentally  true, 
since  the  frequency  and  the  output  both  are  directly 
proportional  to  the  speed  of  the  rotor.  Economical 
design  calls  for  a  working  speed  but  little  less  than  ilie 
safe  maximum  speed  allowed  while,  if  it  is  desired  to 
lower  the  frequency,  the  output  falls  off  in  the  same 
proportion.  Speed  regulation  is  very  important,  par- 
ticularly when  heterodyne  reception  is  used,  because  any 
small  change  in  speed  affects  the  wave  length  and  hence 
the  audio  frequency  beat  note  at  the  receiver.  For  high 
power  long  distance  stations  where  transmission  is  al- 
ways on  the  same  wave  length,  however,  the  alternator 
seems  well  suited. 

The  vacuum  tube  possesses  most  of  the  advantages 
of  both  the  arc  and  the  alternator,  as  a  generator  of 
high  frequency  power.  It  generates  a  pure  continuous 
wave,  without  harmonics,  which  can  be  easily  controlled 
for  telegraphy  by  several  different  methods  or  modu- 
lated for  telephony  and  interrupted  continuous  wave 
telegraphy.  To  change  the  wave  length  it  is  only  neces- 
sary to  adjust  the  master  oscillator  or  exciter  to  the 
value  desired  and  tune  the  antenna  to  this  wave  length. 
It  is  common  practice  to  employ  several  power  amplifier 
tubes  in  parallel  when  high  powers  are  desired.  It  thus 
becomes  possible  to  replace  defective  tubes  by  cutting 
them  out  of  circuit  without  stopping  transmission  nor 
seriously  overloading  the  remaining  tubes.  The  power 
output  may  be  similarly  changed  to  transmit  readily 
over  varying  distances.  Altogether  the  vacuum  tube 
provides  the  simplest  and  most  flexible  means  of  gener- 
ating high  frequency  power.  At  the  present  time  the 
output  of  the  vacuum  tube  sets  does  not  compare  with 
the  arc  or  the  alternator,  largely  due  to  the  high  price 
of  the  tube-  and  its  comparatively  small  power  output. 
Tubes  of  ten  kilowatts  output  have  been  made  and  op- 
erated while  tubes  of  20  kilowatts  and  larger  are  under 
development.  By  using  a  number  of  these  large  tubes 
in  parallel  it  will  be  possible  in  the  near  future  to  build 
vacuum  tube  transmitters  equivalent  in  output  to  the  arc 
and  alternator.  The  power  supply  to  the  plate  circuit 
of  the  large  tubes  will  probably  be  direct  current  at 
10  000  to  50000  volts  obtained  through  hot  cathode  or 
mercury  arc  rectifiers,  from  high  voltage  alternating 
current  supply.  Tube  efficiencies  of  50  to  70  percent 
will  be  obtained. 

In  this  connection  the  recommendations  of  the 
Imperial  Wireless  Telegraphy  Committee  of  England 
appointed  to  investigate  and  recommend  a  system  of 
radio  communication  for  England  and  her  colonies,  will 
be  of  interest.  More  than  a  year  was  spent  in  carefully 
examining  records  and  \  isiting  arc,  alternator  and  tube 
stations  then  in  operation.  After  due  deliberation  the 
committee  reported  in  favor  of  employing  vacuum  tube 
transmitters  entirely  as  the  only  system  which  could  be 
relied  upon  to  give  reliable  service  at  a  reasonable 
expense. 


April,   1 92 1 


THE   ELECTRIC  JOURNAL 


129 


In  conclusion,  continuous  wave  systems  of  radio 
transmission  are  rapidly  replacing  the  damped  wave  or 
spark  systems.  In  the  case  of  transoceanic  stations, 
this  has  already  taken  place  and  will  within  a  few  years 
occur  also  in  the  case  of  ship  to  shore  and  overland 
service.  This  will  be  true  because  continuous  wave  sys- 
tems give  the  greater  distance  of  communication  per 
dollar  of  investment  (a  fact  which  will  finally  determine 
the  system  to  be  used)   and  at  the  same  time  allow  a 


greater  number  of  communications  to  take  place  simul- 
taneously. At  the  present  time  arc  converters  are  used 
in  all  ]).  '-s  from  2  to  1000  kw.  The  high  frequency 
alternatoi  i  ^  ised  mainly  for  transoceanic  communica- 
tion. The  vavuum  tube  seems  destined  ultimately  to  re- 
place both  the  arc  and  the  alternator,  having  the  elec- 
trical advantages  cf  both  and  the  disadvantages  of 
neither. 


W\x'/  IIls^i  yrDq((Oiiey  tor  .lladladon? 


J.  SLEPIAN 

Research  Laboratory, 
Westiiigliousc  Electric  &  Mfg.  Company 


WHEN  asked  to  write  a  paper  on  this  subject,  the 
author  was  considerably  nonplussed.  Begin- 
ning with  Maxwell  who  laid  the  foundation, 
and  followed  by  numerous  other  mathematical 
physicists,  most  notably  Lorenz  who  introduced  his 
beautiful  and  most  useful  retarded  potentials,  the  litera- 
ture abounds  in  integral  signs,  partial  diiTerential  equa- 
tions and  the  symbols  of  vector  analysis.  Was  it 
possible  to  explain  the  theory  of  Maxwell  and  its  con- 
sequences in  ordinary  English,  when  all  the  refinements 
of  higher  mathematics  have  served  to  trace  these  con- 
sequences in  detail  in  only  a  few  simple  cases? 

In  the  following  discussion,  the  author  has  at- 
tempted to  show,  in  a  qualitative  way  only,  how  the  in- 
troduction of  Maxwell's  displacement  currents,  com- 
bined with  the  previously  held  laws  of  electromagnet- 
ism,  explain  the  fact  that  electric  and  magnetic  fields 
are  propagated  with  a  iinite  velocity,  and  how  it  is  that 
a  rapidly  varying  current  continually  gives  out  energy 
to  space.  As  a  beginning  a  review  is  given  of  the  laws 
of  electromagnetism  previous  to  Maxwell,  which  are 
practically  the  electromagnetism  of  the  electrical  engi- 
neer of  today. 

PRE-MAXWELLIAN   ELECTROMAGNETISM 

An  electric  current  is  always  surrounded  by 
a  magnetic  field,  the  lines  of  force  of  which  form 
closed  loops  encircling  the  current.  The  magneto- 
motive force  around  a  loop,  that  is,  the  length  of 
the  loop  multiplied  by  the  average  magnetic  force  along 
it,  is  proportional  to  the  total  current  en'./osed  by  the 
loop,  the  factor  of  proportionality  depending  on  the 
kind  of  units  used.  Fig.  i  (a)  si:- ws  the  case  of  a 
portion  of  a  long  straight  conduct  1 .  where  /  is  the  cur- 
rent, and  H  the  magnetic  force. 

Faraday's  law  of  induction 

Faraday  discovered  that  .1  varying  magnetic  flux 
surrounds  itself  with  a  field  of  electric  force  in  a 
manner  entirely  similar  to  the  way  a  continuous  cur- 
rent surrounds  itself  with  a  field  of  magnetic  fo'rce. 
The  direction  of  the  loops,  however,  is  opposite.     Fig. 


I  (b)  shows  the  field  set  up  b}  'n\  increasing  long 
.-traight  magnetic  flux.  This  might  repiosent,  for  ex- 
ample, a  leg  of  a  core  type  transformer.  -,j-  stands 
for  the  rate  of  change  of  magnetic  flux  and  E  for  the 
electric  force.  The  electromotive  force  around  a  locp, 
that  is  the  length  of  the  loop  multplied'  by  the  average 
electric  force  along  it  is  proportional  to  the  rate  of 
change  of  flux  enclosed  by  the  loop,  the  f.ictor  of  pro- 
portionality depending  on  the  units  used.  This  electr-/- 
motive  force  is  the  e.m.f.  per  turn  of  the  transfomii..- 
engineer. 

It  is  desirable,  for  the  sake  of  the  <-xamples  co  be 
taken  up  further  on,  to  consider  the  electric  field  pro- 


(a)  (b)  (c) 

FIG.    I    (a) — M.-\GNE.TIC  FIELD  PRODUCED  BY  A  CURRENT  ]■' OWING   IN 

A  LONG  STRAIGHT  CONDUCTOR 
FIG.    I    (b) — FIELD  SET  UP  BY  AN  INCREASING  LONG  STRAIGHT  FM'N 
FIG.    I     (c) — FIELD   PRODUCFJ)    BY    A    VARYING    CLOSED    LOOP   OF    I'Ll'X 

duced,  not  by  a  long  straight  var}'ing  magnetic  flu.x  but 
by  a  varying  closed  loop  of  flux.  This  is  shown  in  I'lg. 
I   (c). 

PRE-MAX\\I:LLIAN  rise  and  fall  of  CURRE'VT 

Let  us  see  what  these  two  field  relations  give  svhen 
applied  to  the  following  example.  In  a  long  straight 
conductor,  let  the  current  start  at  zero,  and  begin  in- 
creasing at  a  definite  rate.  After  a  certain  time,  let  it 
stop  increasing  and  remain  constant  for  a  while,  and 
then  let  it  decrease  at  a  constant  rate  to  zero  again. 
The  graph  of  this  is  shown  by  the  curv'e  /,  Fig.  2.  The 
relation  between  the  current  and  the  magnetic  field  de- 
scribed above,  when  applied  to  this  example,  requires 


I30 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


that  a  magnetic  field  such  as  that  pictured  in  Fig.  i  (a) 
spring  up  at  once  throughout  all  space  on  the  first  ap- 
pearance of  current,  and  increase  in  strength  propor- 
tionally with  the  current.  When  the  current  slops  in- 
creasing, the  magnetic  field  ever>'where  must  stop  in- 
creasing ;  when  the  current  decreases,  the  magnetic  field 
everywhere  must  decrease  and,  when  the  current  be- 
comes zero,  the  magnetic  field  must  have  disappeared 
everywhere.  Thus,  according  to  this  theory  there  is  no 
finite  propagation  time,  but  the  magnetic  force  at  any 
point,  however  distant,  instantly  takes  a  value  corre- 
sponding to  whatever  current  is  flowing  in  the  con- 
ductor. 

The  second  relation,  Faraday's  law  of  induction, 
shows  that,  during  the  rise  of  current,  a  field  of  electric 
force  is  set  up.  Studying  Fig.  i  (c)  and  applying  it  to 
this  example,  we  get  the  field  shown  in  Fig.  3.  Near 
the  conductor,  the  lines  of  electric  force  are  parallel  to 
the  current,  but  in  the  opposite  direction.  Inside  the 
conductor,  the  electric  field  forms  the  counter  e.m.f.  of 
self-induction  of  the  electrical  engineer.  Curve  E,  Fig. 
2,  shows  the  electric  force  due  to  the  current  in  con- 
ductor.    According   to    this    theory,    the    electric    field 


/ 

/ 

\ 

/ 

E 

/  E' 

\" 

eM. 

F 

\e' 

E 

;e' 

FIG.    2 — EFFElT    of    .\1.\X\\E1.].  ^    1>1M']..\CEMENT   CURRENTS    OX 
R.\DI.\TION  OF  POWER 

Springs  full  fledged  to  its  proper  value  the  instant  the 
current  begins  to^  rise,  and  disappears  instantly  when 
the  current  stops  increasing. 

During  the  period  when  it  is  increasing,  the  current 
does  work,  represented  at  each  moment  by  the  product 
of  E  and  /,  Fig.  2.  When  decreasing,  the  current  has 
work  done  on  it  at  a  rate  given  by  the  same  product. 
These  two  amounts  of  work  are  evidently  equal.  Ac- 
cording to  the  Pre-Maxvvellian  theory,  the  first  repre- 
sents the  storing  of  energv'  in  the  magnetic  field,  and 
the  second  its  complete  return  to  the  conductor.  Thus, 
in  the  Pre-Maxwellian  theon,%  there  is  no  room  for 
radiation.  Whatever  energ\'  is  given  up  to  space  when 
a  current  increases  is  not  lost,  but  is  stored  there  as 
magnetic  energ}-,  ready  to  be  returned,  years  later  per- 
haps, when  the  current  decreases. 

WEAKNESS  OF  THE  PRE-M.^XWELLI.\N  THEORY 

Although  the  Pre-Maxwellian  theory  does  not  fit 
the  facts  for  high  frequencies,  it  does  come  very  close 
to  the  truth  for  currents  of  moderate  frequency.  \\'ere 
this  not  so,  the  present-day  education  of  our  60  cycle 
engineers  would  have  to  be  considerably  modified. 
Since  Maxwell  had  no  knowledge  of  high-frequency 
phenomena,  it  is  interesting  to  speculate  as  to  what  it 


was  that  he  found  unsatisfactory  in  the  theory  as  then 
developed.  Probably  he  found  greatest  difficulty  in  ac- 
cepting the  theory  of  immediate  response  of  the  mag- 
netic field  at  any  point,  to  changes  in  a  distant  current. 
Possibly  also  the  instantaneous  rise  to  finite  values  of 
the  electric  field,  as  shown  above,  was  not  compatible 
with  his  ideas  of  energy  stored  in  an  electric  field. 
These  difficulties  were  entirely  removed  by  his  hypothe- 
sis as  to  displacement  currents.  The  subsequent  ex- 
perimental confirmation  by  Hertz  of  the  consequences 
of  this  hypothesis  put  it  on  as  firm  a  basis  of  fact  as  the 
other  laws  of  electromagnetism. 

maxwell's  displacement  CURRENT 

Just  as  a  varying  magnetic  flux  surrounds  itself 
with  an  electric  field,  so  a  varying  electric  flux  sur- 
rounds itself  with  a  magnetic  field.  This  is  the  new  law 
of  electromagnetism  introduced  by  Maxwell.  An  in- 
creasing electric  flux  produces  a  magnetic  field  in  all  re- 
spects  like  a   conduction   current,   as   shown   in  Fig.  4. 


FIG.   3 — FIELP  OF  ELECTRIC  FORCE  SET   I'P  DURI.Vt;  THE  RISE  OF       . 
CURRENT 

Hence  the  name  "displacement"  current  which  ^laxwell 
gave  to  varying  electric  flux.  We  must  now  modify  our 
previous  statement  and  say  that  the  magnetomotive 
force  round  a  loop  is  proportional  to  the  total  current 
enclo.sed,  conduction  plus  displacement  currents. 

NrAXWELLIAN  RISE  AND  FALL  OF  A  CURRENT 

Consider  now  how  the  introduction  of  the  magnetic 
effects  of  the  displacement  current  alters  the  fields  pro- 
lUiced  by  the  rising  and  falling  current  considered 
before.  Consider  the  average  electric  force  in  an 
annulus  surrounding  the  conductor,  and  of  the  same 
area  as  the  conductor  cross-section.  Fig.  5.  The  elec- 
tric force  cannot  rise  instantly  to  a  finite  value  as  in  the 
Pre-Maxwellian  theory.  In  fact,  the  rate  of  rise  of 
electric  force  in  this  annulus  must  be  less  at  any  moment 
than  the  conduction  current.  For,  if  it  were  equal  to 
the  conduction  current,  since  it  is  oppositely  directed, 
the  total  current,  conduction  plus  displacement  would 
he  zero,  and  there  would  be  no  magnetic  field  at  a  radius 
greater  than  that  of  the  annulus.  The  rise  of  the  elec- 
tric field  near  the  conductor,  therefore,  follows  a  curve 


April,   1 92 1 


THE  ELECTRIC  JOURXAL 


131 


like  the  dotted  one  shown  in  Fig.  2.  Actually,  at  the 
first  instant,  when  the  conduction  current  is  small,  the 
displacement  current  in  the  annulus  equals  the  conduc- 
tion current  and  the  magnetic  field  at  the  rim  of  the 
annulus  is  zero.  This  transient  condition,  quickly 
passes  as  the  conduction  current  rises.  At  a  greater 
distance  from  the  conductor,  because  of  the  greater 
area  looped  by  magnetic  lines  and  therefore  the  larger 
section  over  which  displacement  current  is  to  be  in- 
tegrated, the  total  displacement  current  stays  equal  to 
the  conduction  current  for  a  longer  time,  so  that  the 
magnetic  force  at  that  point  does  not  begin  to  rise  until 
some  time  after  the  conduction  current  started.  In 
other  words,  at  any  instant,  the  magnetic  field  reaches 
out  to  such  a  radius  that  the  displacement  current 
within  that  radius  equals  the  conduction  current. 
Beyond  that  radius  at  that  moment  there  is  no  field.  We 
thus  arrive  at  a  finite  rate  of  propagation  of  the  field 
set  up  by  the  current. 

Just  as  the  electric  force  at  the  conductor  rises 
gradually  and  not  instantaneously  when  the  current  be- 
gins to  change,  so  also  the  electric  force  falls  off  gradu- 
ally and  not  instantaneously  when  the  current  stops 
changing.     The  complete  cur\e  for  the  electric  force  at 


C" 


(])" 


FIG.   4 — MAGNETIC       FIELD 
DUE  TO   INCREASING   FLUX' 


FIG.    5 — ELECTRIC  FORCE 

SURROUNDING     THE     CON- 

PUCTOR 


the  conductor  is  given  by  the  dotted  curve  £',  of  Fig.  2. 
Let  us  compare  this  with  the  full  line  curve  £,  showing 
the  counter  e.m.f.  of  self-induction  according  to  the 
Pre-Maxwellian  notions.  We  see  that  £'  is  smaller 
than  E  at  the  start  when  I  is  small,  and  that  £'  is  larger 
than  E  for  a  short  interval  after  /  attains  its  constant 
maximum  value.  Hence,  in  building  up  the  current.  / 
from  zero  to  its  full  value.  Maxwell's  theory  requires  a 
greater  expenditure  of  work  than  called  for  by  the  older 
theory.  Again,  when  the  current  begins  to  decrease,  £' 
is  less  than  £  :  and  it  is  not  until  /  is  zero  that  £'  is 
greater  than  £  and  E'l  becomes  zero  or  has  no  energy 
value.  Hence  Maxwell's  theory  returns  less  energy  to 
the  circuit  when  the  current  decreases  than  the  older 
theory.  Hence,  as  a  net  result  of  bringing  the  current 
up  and  then  down  again,  energy  has  been  lost  to  the 
medium  carrying  the  electric  and  magnetic  fields.  In 
other  words,  energy  must  be  radiated  into  space. 

-Studying  the  curves  of  Fig.  2,  it  is  seen  that  the 
curve  £'  lags  or  is  delayed  in  time  over  £.  It  is  fairly 
clear,  that  if  /  was  an  alternating  current,  £  and  £' 
would    be    alternating   quantities,    and    £,    the    counter 


e.m.f.  of  self-induction  according  to  the  older  theory, 
would  be  in  time  quadrature  with  /.  The  true  counter 
e.m.f.  £'  would,  therefore,  lag  behind  the  quadrature 
position.  The  electromagnetic  reactions  on  an  alternat- 
ing current,  therefore,  have  not  only  a  component  of 
e.m.f.  in  quadrature  with  the  current,  corresponding  to 
the  self-induction  of  the  circuit,  but  also  a  component 
of  e.m.f.  opposite  in  f)hase  to  the  current,  correspond- 
ing to  the  so-called  radiation  resistance. 

WHY  HIGH  FREQUEXCY? 

We  are  now  able  to  answer  the  question  of  the 
paper.  Without  the  displacement  currents,  we  would 
have  no  radiation.  In  proportion  as  the  displacement 
currents  play  a  greater  part  in  detemiining  the  mag- 
netic field,  more  energ)-  is  lost  to  space  by  an  alter- 
nating current.  Now  the  displacement  current  is  pro- 
portional to  the  rate  of  change  of  electric  force,  and 
the  electric  force  is  proportional  to  the  rate  of  change 
of  the  current.  Hence,  the  more  rapidly  the  current 
alternates,  the  greater  will  be  the  relative  proportion  of 
displacement  current  to  conduction  current.  In  fact, 
since  a  double  differentiation  is  involved,  the  radiation 
will  vary  as  the  square  of  the  frequency. 

WHY    RADIATE? 

Why  not  let  a  sending  circuit  act  directly  on  a  re- 
ceiving circuit  by  transformer  action,  or  mutual  induc- 
tion, in  the  manner  fainiliar  to  the  electrical  engineer? 
A  comparison  of  the  force  at  a  distance  produced  by 
the  two  types  of  field  provides  the  answer. 

Formulae  for  the  field  produced  by  a  steady  cur- 
rent in  a  finite  circuit  show  that  the  magnetic  force  at 
great  distances  \aries  inversely  as  the  iljJ^  "jiower  of 
the  distance.  What  is  the  law  for  radiated  fields?  In 
this  case,  the  radiated  energy  spreads  out  in  spherical 
waves.  .Since  the  total  energy  in  a  wave  stays  constant 
as  the  wave  spreads  out,  the  energy  densit\-  must  vary 
inversely  as  the  area  of  the  wave  front,  and  therefore 
inversely  as  the  square  of  the  radius.  The  energy 
density,  however,  is  proportional  to  the  square  of  the 
magnetic  force.  Hence  the  magnetic  force  in  a  radi- 
ated field  varies  inversely  as  the  first  power  of  the  dis- 
tance. For  great  distances  this  gives  an  enormous  ad- 
vantage over  the  inverse  (J^  law  for  steady  fields. 

While  it  has  been  shown  that  for  a  given  current, 
the  higher  frequencies  give  out  more  power  as 
radiation,  it  does  not  follow  in  all  cases  that  the  highest 
frequencies  are  the  best  for  radio  transmission.  Radi- 
;'lion  given  oft'  by  a  transmitting  station  must  pass 
through  the  air  and  over  the  earth  to  the  receiving  sta- 
tion. During  tliis  passage,  it  loses  energj'  due  to  the 
currents  induced  in  the  earth  and  in  ionized  strata  of 
the  atmosphere.  It  has  been  found  experimentally  that 
the  energv  loss  of  this  nature  increases  with  the  fre- 
quencv.  Hence  for  transmission  to  great  distances  it 
has  been  found  more  practical  to  use  lower  frequencies, 
(3000  to  loofxT  meters),  even  though  greater  antenna 
current  is  necessary  to  radiate  a  given  energy. 


ajul  To^i:^  oii  10  000  Cycle  Per  -Socojavl 

B.  G.  LAMME 

Chief  Engineer, 
Westinghouse  Electric  &  Mfg.  Company 

THE  FOLLOWIXG  ARTICLE  is  slightly  condensed  from  a  paper  the  author  presented  before  the 
American  Institute  of  Electrical  Engineers  in  May  1904,  a  year  or  so  after  the  machine  described  was 
built  and  tested.  It  is  reproduced  here  because,  as  explained  in  an  editorial  in  this  issue,  this  early  machine 
represents  such  a  complete  anticipation  of  recent  practice,  at  least  one  akeniator  along  very  similar  lines 
being  in  use  for  transoceanic  radio  work,  while  others  are  contemplated.  The  close  similarity  between 
these  modern  high-frequency  machines  and  the  one  which  was  designed  in  1902,  gives  striking  evidence  of 
the  clear  insight  into  correct  principles  which  governid  the  original  design.  (Ed.) 


THE  STARTING  POINT  in  this  machine  was 
the  sheet  steel  to  be  used  in  the  armature.  No 
direct  data  were  at  hand  showing  losses  in  sheet- 
steel  at  such  high  frequencies,  nor  was  there  at  hand 
any  suitable  apparatus  for  determining  such  losses.  As 
preliminary  data,  tests  at  frequencies  up  to  about  140 
cycles  per  second  were  used,  and  results  plotted  for 
different  thicknesses  of  sheet  steel.  Also,  tests  were  ob- 
tained showing  the  relative  losses  due  to  eddy  currents 
and  hysteresis,  and  these  were  plotted,  taking  into  ac- 
count the  thickness  of  the  sheet.^.  These  data  were  not 
consistent  through- 
out; but  the  general 
shape  of  the  curves 
was  indicated,  and  in 
this  way  the  probable 
loss  at  the  frequency 
of  10  000  cycles  per 
second  was  estimated 
for  the  tfiial^est  sheet 
steel  obtainable.  The 
steel  finally  secured 
for  this  machine  was 
in  the  form  of  ribbon 
about  2  in.  wide,  and 
about  0.003  in.  tliick, 
which     was     much  w-'' 

thinner  than  steel  used  in  commercial  dynamos  or 
transformers,  which  varies  from  O.125  to  0.0280  inch. 
Therefore  the  machine  had  to  be  designed  with  the  in- 
tention of  using  this  narrbw  ribbon  of  steel  for  the 
armature  segments. 

A  second  consideration  in  the  construction  of  such 
a  machine  is  the  number  of  poles  permissible  for  good 
mechanical  constnaction.  For  instance,  at  3000  r.p.in. 
— which  was  adopted  as  normal  speed — the  number  of 
poles  is  400  for  10  000  cycles  per  second.  The  frequency, 
expressed  in  terms  of  alternations  per  minute,  mul- 
tiplied by  the  pole  pitch  in  inches,  gives  the  peripheral 
speed  in  inches.  At  i  200  000  alternations  per  minute 
(or  10  000  cycles  per  second)  and  a  pole  pitch  of  0.25 
in.,  for  example,  the  peripheral  speed  of  the  field  will 
be  25  000  feet  per  minute.  Thus  it  was  evident  that 
either  a  pole  construction  should  be  adopted  which 
would  stand  this  high  peripheral  speed,  or  the  pole-pitch 


should  be  less  than  0.25  in.  It  was  finally  decided  that 
an  inductor  type  of  alternator  would  be  the  most  con- 
venient construction  for  this  high  frequency.  With  the 
inductor  type  alternate  poles  could  be  omitted,  thus  al- 
lowing 200  pole  projections,  instead  of  400.  The  field 
winding  could  also  be  made  stationary  instead  of  rotat- 
ing, which  is  important  for  such  a  high  speed.  This 
construction  required  a  somewhat  larger  machine  for  a 
given  output  than  if  the  usual  rotating  type  of  machine 
were  adopted;  but  in  a  machine  of  this  type  where 
everything  was  special,  the  weight  of  material  was  of 

comparatively  little 
importance,  and  n  o 
attempts  were  made 
to  cut  the  weight  or 
cost  of  the  machine 
down  to  the  lowest 
possible  limits. 

The  following 
covers  a  general  de- 
scription of  the  elec- 
trical and  magnetic 
features  of  the  ma- 
chine : — 

ARMATURE 

The  armature 
was  built  up  in  two 
laminated  rings  dovetailed  into  a  cast-iron  yoke,  as  in- 
dicated in  Fig.  I.  The  laminations  were  made  in  the 
form  of  segments  dovetailed  to  the  cast-iron  yoke,  Fig. 
2.  Special  care  was  taken  that  the  laminations  made 
good  contact  with  the  cast-iron  yoke,  as  the  magnetic 
circuit  is  completed  through  the  yoke. 

The  armature  sheet  steel  consisted  of  plates  of 
0.003  in.  thickness.  The  sheet  steel  was  not  annealed 
after  being  received  from  the  manfacturer;  it  was  so 
thin  that  to  attempt  annealing  was  cojisidered  inadvis- 
able. To  avoid  eddy  currents  between  plates  each  seg- 
ment was  coated  with  a  thin  paint  of  good  insulating 
quality.  This  painting  was  a  feature  requiring  con- 
siderable care  and  investigation,  as  it  was  necessary  to 
obtain  a  paint  or  varnish  which  was  very  thin,  and 
which  yould  adhere  properly  to  the  unannealed  lamina- 
tions. These  laminations  had  a  bright  polished  appear- 
ance quite  diflferent  from  that  of  ordinary  steel.     They 


April,  1921 


THE  ELECTRIC  JOURNAL 


133 


^r^    /r^ 


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were  so  thin  that  the  ordinarj'  paint  or  varnish  used  on 
sheet  steel  made  a  relatively  thick  coating,  possibly  al- 
most as  thick  as  the  plates  themselves.  A  very  thin 
varnish  was  finally  obtained  which  gave  a  much 
thinner  coating  than  the  plate  itself,  so  that  a  rela- 
tively small  part  of  the  armature  space  was  taken 
up  by  the  insulation  between  plates. 

Each  armature  ring  or  crown  has  400  slots. 
Each  slot  is  circular  and  0.6625  inch  diameter,  Fig. 
3.  There  is  0.03125  inch  opening  at  the  top  of  the 
slot  into  the  air-gap,  and  the  thickness  of  the  over- 
hanging tip  at  the  thinnest  point  is  0.03125  inch. 
The  armature  winding  consists  of  No.  22  wire, 
B.  &  S.  gage,  and  there  is  one  wire  per  slot.  The 
entire  winding  is  connected  in  series,  Fig.  4.  The 
measured  resistance  of  the  winding  is  1.S4  ohms  at 
25  degrees  C. 

After  the  sheet  steel  was  built  up  in  the  frame, 
it  was  grotmd  out  carefully.  The  laminations  were 
then  removed,  all  burred  edges  taken  off  and  the 
laminations  again  built  up  in  the  frame.  The 
object  of  this  was  to  remove  all  chance  of  eddy 
currents  between  the  plates  due  to  filing  or  grind- 
ing. The  finished  bore  of  the  armature  is  25.0625 
inch. 

FIELD  OR  INDUCTOR 

This  was  made  of  a  forged-steel  disc  25  in. 
diameter  turned  into  the  proper  shape,  and  the 
poles  were  formed  on  the  outside  by  slotting  the 
periphery  of  the  ring.  The  general  construction 
is  indicated  in  Figs,  i  and  5.     The  poles  were  0.125 


rudiijis 


in.  wide  and  about  0.75  in.  long  radially  and 
were  round  at  the  pole-face.  Fig.  6  shows  the 
general  dimensions  of  a  pole. 

The  field  winding  consisted  of  No.  21  wire, 
B.  &  S.  gage.  There  were  600  turns  total  ar- 
ranged in  30  layers  of  20  turns  per  layer.  The 
field  coil  after  being  wound  was  attached  to  a 
light  brass  supporting  ring.  The  general  ar- 
rangement of  the  field  or  inductor,  armature 
yoke  and  bearings,  is  as  indicated  in  Fig.  i.  The 
measured  resistance  of  the  field  winding  is  53.8 
ohms  at  25  degrees  C. 


The  machine  was  designed  primarily  for 
only  a  small  output,  but  was  operated  on  tem- 
porary test  up  to  2  kw.  A  series  of  curves  were 
taken  at  500,  1000,  1500,  2000,  2500,  and  3000 
r.p.m.,  giving  frequencies  from  1667  to  10  000 
cycles  per  second.  At  each  of  these  speeds, 
saturation  curves,  iron  losses,  and  short-circuit 
tests  were  made.  Friction  and  windage  were 
also  measured  at  each  speed.  On  account  of  the 
high  frequency,  the  machine  was  worked  at  a 
very  low  induction ;  consequently  there  is  an  ex- 
tremely wide  range  in  pressure,  the  normal  op- 
erating pressure  being  taken  at  approximately 

150  volts. 

On  curve  sheet  No.  i,  the  saturation  curves  for  the 

various   speeds  are  given.     These  curves  check  fairly 


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134 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


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well,  the  pressure  being  practically  [jroportional  to  the 
speed  with  a  g^iven  field  charge.  This  is  to  be  expected 
at  the  lower  speeds,  but  it  was  considered  possible  that 
at  3000  r.p.m.  air-gap  might  be  slightly  lessened,  due  to 
the  expansion  of  the  rotor  under  centrifugal 
action;  and  it  was  also  thought  that  eddy-cur- 
rent loss  due  to  the  high  frequency  might  affect 
the  distribution  of  magnetism  at  the  armature 
face ;  but  the  armature  iron  losses  were  com- 
paratively small,  and  there  appeared  to  be  no 
such  effect.  Also  there  appeared  to  be  no  effect 
due  to  expansion  at  high  speed.  The  air-gap 
specified  for  this  machine  is  0.03125  in.  on  each 
side  or  0.0625  in.  total.  A  veiy  small  variation 
in  the  diameter  of  the  inductor  or  the  bore  of 
the  armature  would  make  a  relatively  large  per- 
cent in  the  effective  air-gap.  Therefore  no  re- 
liable calculations  can  be  made  on  the  saturation 
curves  of  this  machine  based  upon  the  specified 
air-gap. 

Curve  sheet  No.  2  shows  the  iron  losses  at 
various  speeds  from  500  to  3000  r.p.m. — 1667  to 
10000  cycles  per  second.  These  losses  are 
plotted  in  terms  of  watts  for  a  given  exciting 
current.  The  curves  show  a  rather  unexpected 
condition  as  regards  the  losses.  According  to 
the  original  data  showing  the  relative  losses  due 
to  eddy-currents  and  hysteresis,  the  eddy-cur- 
rent loss  even  with  these  thin  plates  should  have 
been  much  higher  than  the  hysteresis  loss,  but 


these  iron  loss  curves  show  losses  with  a  given 
field  charge  almost  proportional  to  the  fre- 
quency, which  is  the  ratio  that  the  hysteresis 
loss  alone  should  show.  As  the  eddy-current 
loss  varies  as  the  square  of  the  frequency,  the 
writer  expected  this  to  be  a  large  element  in  the 
total  iron  loss,  especially  at  the  higher  induc- 
tions. The  six  curves  shown  on  this  test-sheet 
are  fairly  consistent  with  each  other,  but  it 
should  be  remembered  that  in  making  measure- 
ments of  such  abnormal  apparatus  little  dis- 
crepancies in  the  curves  could  easily  creep  in. 
For  instance,  in  the  saturation  curve  a  series  of 
experiments  were  first  made  to  find  whether 
usual  types  of  voltmeters  were  satisfactory,  and 
a  number  of  different  methods  for  checking 
these  readings  were  used.  In  determining  the 
iron  losses  in  curve  sheet  No.  2,  the  machine  was 
driven  by  a  small  motor  and  the  losses  measured 
with  different  field  charges.  Under  most  con- 
ditions of  test  the  iron  loss  was  a  small  element 
of  the  total  loss,  and  therefore  slight  variations 
in  the  friction  loss  would  apparently  show  large 
variations  in  the  iron  losses.  Also  the  flywheel 
capacity  of  the  rotating  part  of  the  alternator 
was  comparatively  high.  Therefore,  if  there  are 
any  variations  in  the  circuits  supplying  the  driv- 
ing motor,  there  would  tend  to  be  considerable  fluctua- 
tions in  the  power  supplied.  Considering  all  the  condi- 
tions of  test,  the  curves  appear  to  be  remarkably  con- 


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Field  Amperes 


April,   1921 


THE  ELECTRIC  JOURNAL 


135 


Curve  sheet  No.  3  shows  the  short-circuit  curves  at 
speeds  of  1000,  2000,  and  3000  rev.  per  min.,  or  fre- 
quencies of  3333,  6667,  and  10  000  cycles  per  second, 
respectively.  It  should  be  noted  that  at  a  given  fre- 
quency the  short-circuit  current  is  proportional  to  the 
field  current  over  the  entire  range  measured  but  that 
the  short-circuit  current  is  not  the  same  for  the  same 
field  current  at  the  various  frequencies.  According 'to 
these  curves  the  current  on  short  circuit  increases  some- 
what with  the  given  field  charge  as  the  fre- 
quency is  increased. 

Curve    sheet    No.    4    shows    the    measured 
wmdatre   and   friction   losses   plotted   at   speeds 
from  500  to  3000  rev.  per  min.     This  curve  in- 
dicates clearly  that  the  windage  is  the  principal 
friction  loss  at  the  higher  speeds.     The  writer 
has   added   two   curves,   one   showing  the   esti- 
mated bearing  friction   loss,  and  the  other  the  «•«  140 
estunated  windage,  based  upon  the  assumption 
that  the  bearing  friction  varies  directly  as  the 
revolutions  and  the  windage  loss  with  the  third 
power  of  the  revolutions.     The  small  circles  ly- 
mg  close  to  the  measured  loss  curve  .show  the  03  125 
sum  of  these  estimated  losses,  and  the  agreement 
with  the  measured  loss  is  fairly  close  over  the  "•*  i» 
entire  range. 

Curve  sheet  No.  5  shows  regulation  tests 
made  at  150  volts.  The  power-factor  of  the 
load  on  this  test  was  not  determined,  as  it  was 


extremely  difficult  to  make  accurate  measure- 
ments. The  load  consisted  of  incandescent 
lamps  and  the  wiring  from  the  machine  to  the 
lamps  was  non-inductive  for  the  usual  fre- 
quencies; but  at  the  abnormal  frequency  of 
10  000  cycles  per  second  it  is  more  difficult  to 
obtain  a  true  non-inductive  load  with  ordinary 
apparatus.  The  tested  regulation  indicates  that 
the  load  was  practically  non-inductive. 

In  first  undertaking  tests  on  this  machine 
there  was  considerable  difficulty  in  measuring 
the  pressures.  It  was  found  that  at  a  frequency 
of  10  000  cycles  per  second  the  Weston  volt- 
meter did  not  work  satisfactorily.  Practically 
the  same  deflection  was  obtained  on  the  high 
and  low  scales  of  a  60-120  volt  Weston  alternat- 
ing-current direct-current  voltmeter  with  the 
same  pressure. 

\'ery  good  results  were  obtained  by  the  use 
of  a  form  of  static  voltmeter  devised  by  Mr. 
Miles  Walker*.  Tests  were  also  made  with  the 
Cardew  hot-wire  voltmeter  with  the  high  fre- 
quencies, and  the  results  checked  ven,^  satisfac- 
torily with  the  static  voltmeter. 

For  measuring  the  current  a  current 
dynamometer  was  used  which  had  wood  upright 
supports  and  a  celluloid  dial.  The  only  metal 
parts  outside  of  the  copper  coils  were 
brass  screws.  It  was  found  that  the  current  dynamo- 
meter is  not  affected  by  frequency,  unless  there  are  ad- 
jacent metal  parts  in  which  eddy  currents  can  be 
generated  which  react  upon  the  moving  element.  The 
dynamometer  used  had  but  a  few  turns  in  order  to  re- 
duce the  pressure  drop  across  it.  This  dynamometer 
was  checked  very  carefully  at  different  frequencies  and 

•^This  voltmeter  is  of  the  same  form  as  the  static  wattmeter 
described  by  Mr.  Walker  before  the  A.  I.  E.  E.,  May,  1902. 


3  S 
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10000  Cj-cles  (>er  Stecond 

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136 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


apparently  gave  similar  results  for  any  frequency  be- 
tween 25  and  10  000  cycles. 

Several  temperature  tests  were  made  on  this  ma- 
chine. The  heaviest  load  on  any  test  was  13.3  amperes 
at  150  volts,  or  2-kw  output.  This  test  was  of  two  hours' 
duration,  and  at  the  end  the  armature  iron  showed  a  rise 
of  16  degrees  C. ;  the  armature  copper  21  degrees  C.  by 
resistance,  and  the  field  copper  17.3  degrees  C.  Air 
temperature  19  degrees  C.  The  machine  showed  a  re- 
latively small  increase  in  temperature  at  thi«  load  over 
the  temperature  rise  with  one-third  this  load.  This  was 
probably  due  to  the  fact  that  the  windage  loss  was  so 
much  higher  than  the  other  losses  of  the  machine  that 
the  temperature  was  but  little  affected  by  the  small  addi- 
tional loss  with  increase  in  load. 

Attempts  were  made  to  utilize  the  current  from  this 
machine  for  various  experiments,  but  difficulty  was  at 


once  found  in  transforming  it.  At  this  high  frequency 
no  suitable  iron-cored  transformer  was  available. 
Transfonners  with  open  magnetic  circuits  were  tried 
and  operated  better  than  those  with  iron  cores  but  were 
still  rather  unsatisfactory.  It  was  decided  that  nothing 
could  be  done  in  this  line  without  building  special  trans- 
formers. 

Among  the  few  experiments  made  was  that  of 
forming  an  arc  with  current  at  this  high  frequency. 
This  arc  appeared  to  be  like  an  ordinary  arc  so  far'as 
the  light  was  concerned,  but  had  a  very  high-pitched 
note  corresponding  to  the  high  frequency.  This  note 
was  very  distressing  to  the  ears.  This  machine  is  in 
reality  of  the  nature  of  a  piece  of  laboratory  apparatus; 
and  at  present  (1904)  it  has  no  commercial  value.  It 
was  designed  primarily  for  scientific  investigation,  and 
appears  to  be  a  very  good  machine  for  that  purpose. 


Coiitiniious  1^7nvo  lla^llo  jlocolvDr^ 

M.  C.  BATSL'L 

Radio  Engineer, 
Wcstinghouse  Electric  &  Mfg.   Company 

The  extensive  use  of  continuous  waves,  or  waves  having  a  constant  amplitude,  is  only  possible  througli 
the  use  of  the  heterodyne  method  of  reception,  invented  by  Prof.  R.  A.  Fessenden.  The  greatly  increased 
selectivity  of  the  receivers  and  freedom  from  interference,  due  to  the  character  of  the  radiated  waves  from 
the  continuous  wave  transmitters,  makes  it  possible  to  operate  more  stations  in  the  same  locality,  than  it  is 
possible  to  operate  using  spark  or  other  damped  wave  transmitters.  A  brief  outline  of  some  methods 
which  have  been  used  and  are  used  at  the  present  time,  for  increasing  the  selectivity  of  the  receiving  cir- 
cuits, detecting  or  rectifying  the  signals  and  for  amplying  the  received  energy  is  given  in  the  following 
article. 


IT  IS  no  longer  po.'isible  to  make  a  simple  list  of  the 
most  practical  or  useful  antenna,  tuning  circuits  or 
detecting  and  amplifying  equipment  for  receiving 
radio  signals.  The  most  useful  equipment  m^st  be  de- 
termined by  the  class  of  service  for  which  the  equip- 
ment is  intended.  Some  of  the  principle  factors  which 
determine  the  type  of  apparatus  to  be  installed  are:— 
J — Strength  of  signals. 

2 — Type  of  signals  to  be  received.     Spark,  modulated 
continuous  waves,  telephone  or  continuous  waves. 
J — Character  of  possible  interference. 
4 — Atmospheric   disturbances. 
.5 — Wave  lengths  to  be  received. 
6 — Reliability  of  service  desired. 

The  forms  of  the  conductors  used  for  receiving 
radio  signals  vary  greatly,  and  depend  upon  the  condi- 
tions at  the  place  of  installation.  The  two  forms  most 
used  are  the  open  antenna  and  the  coil  or  loop  antenna. 
Underground  wires  consisting  of  insulated  wires  buried 
in  the  earth  with  the  receiving  instruments  connected 
between  the  wires  and  ground,  or  between  two  such 
wires,  have  been  used  to  a  certain  extent.  Under- 
ground wires  are  sometimes  placed  in  iron  pipes,  from 
which  they  are  insulated,  and  the  pipes  buried  in  the 
ground. 

In  computing  the  e.m.f.  induced  in  either  open  or 
coil  antennae,  the  same  result  is  obtained  whether  the 
electromagnetic  or  electrostatic  component  of  the  field 
is  considered.  The  e.m.f.  induced  in  an  open  flat-top 
antenna  is  proportional  to  its  height.     The  antenna  is 


usually  tuned  to  the  same  frequency  as  the  induced 
e.m.f.,  that  is,  the  capacity  reactance—,  of  the  antenna, 
is  balanced  by  inserting  an  inductance  of  the  proper 
value  to  produce  an  inductive  reactance  a  L,  so  that  the 
impedance  is  simply  the  resistance  of  the  antenna,  and 
the  current  that  flows  is  /  =  £  -7-  /?. 

In  the  resistance  of  the  antenna  is  included  all  the 
losses  which  give  rise  to  counter-e.m.f.'s  which  oppose 
the  flow  of  current  in  phase  with  the  driving  e.m.f.; 
the  resistance  is  due  to  the  ohmic  resistance  of  the  wire 
and  ground  system,  the  dielectric  losses  and  the  radiated 
energy.  The  radiation  resistance  of  an  antenna  increases 
with  the  height.  It  is  evident,  therefore,  that  if  the 
resistance  of  the  antenna  wires  and  ground  systems 
could  be  sufficiently  reduced,  the  current  would  be  in- 
dependent ofHhe  height  of  the  antenna. 

For  receiving,  the  use  of  a  low  antenna  with  a  low 
effective  height,  may  be  of  great  advantage  if  the  losses 
due  to  the  resistance  of  the  antenna  wire  and  ground 
system  are  small.  For  a  given  field  strength,  a  long 
wave  length  is  also  advantageous  for  receiving,  since 
the  radiation  resistance  decreases  as  the  square  of  the 
wave  length  for  a  given  anteima. 

An  e.m.f.  is  induced  in  a  coil  antenna  by  a  passing 
electromagnetic  wave  because  of  the  time  variation  of 
the  magnetic  flux  through  it.  The  e.m.f.'s  induced  in 
the  two  vertical  sides  of  the  coil,  if  the  plane  of  the  coil 
is  parallel  to  the  direction  of  propagation  of  the  wave, 


April,   1 92 1 


THE   ELECTRIC  JOURNAL 


T^i? 


are  not  in  phase,  due  to  the  time  required  for  the  wave 
to  travel  from  one  side  of  the  coil  to  the  other,  there- 
fore, there  is  a  resulting  e.m.f.  acting  to  send  current 
ihruugii  the  coil.  If  the  plane  of  the  coil  is  per- 
;.endicular  to  the  direction  of  propagation  of  the  waves, 
the  e.m.f.'s  are  in  phase  and  opposed,  so  that  there  is 


Y 


.2* 


;.*-  Detector 
Telephone 


FIG.    I — COMBINATION    OK   A    COIL    ANTENNA    AND   OPEN    ANTENNA 
AS   A   RECEIVING   SYSTEM 

For  eliminating  interference  and  determining  the  direction 
of  a  transmitting  station. 

no  resulting  e.m.f.  The  e.m.f.  acting  to  send  current 
around  the  coil  is  proportional  to  a-  n  I,  where  a  equals 
the  length  of  side  of  a  square  coil,  n  equals  the  number 
of  turns  in  the  coil,  /  equals  the  wave  length.  The  volt- 
age reception  factor,  which  is  useful  in  operating  a  de- 
tector is  o^nL/R,  where  L  equals  the  inductance  of  the 
coil,  and  R  equals  the  resistance  of  coil.  Small  coils 
which  have  several  turns  are  usually  used  for  receiving. 
The  most  efficient  coils  for  the  wave  length  to  be  re- 
ceived are  most  conveniently  determined  experiment- 
ally, because  the  resistance  cannot  be  calculated. 

A  coil  aerial  is  not  as  efficient  for  receiving  over  a 
wide  range  of  wave  lengths,  as  an  open  antenna,  due 
chiefly  to  the  fact  that  the  e.m.f.  induced  in  the  coil 
varies  inversely  as  the  wave  length,  while  it  does  not 
vary  with  the  wave  length  in  the  case  of  an  open 
antenna.  The  directional  properties  of  coil  antennae 
are  utilized  for  reducing  interference,  by  rotating  the 
coil  so  that  a  zero  is  obtained  on  the  wave  from  the  in- 
terfering station,  while  the  desired  signals  can  be  re- 
ceived, provided  the  two  stations  and  the  coil  are  not 
in  line. 

Coil  antennae  are  used  for  finding  the  direction  of 
transmitting  stations  and,  when  one  is  used  in  combina- 
tion with  an  open  antenna,  it  is  possible  to  determine  the 
direction  of  the  transmitting  station.  The  combination 
of  a  coil  and  open  antenna  as  a  receiving  system,  when 
connected  as  shown  in  Fig.  i,  may  be  employed  for 
eliminating  the  interference  caused  by  a  nearby  trans- 
mitting station,  or  for  determining  the  absolute  direc- 
tion of  a  transmitting  station. 

The  elimination  of  the  interfering  signals  is  accom- 
plished as  follows.  The  coil  antenna  is  tuned  to  the  de- 
sired signal,  that  is,  the  values  of  inductance  and  ca- 
pacitance are  adjusted  to  neutralize  each  other  at  the 
desired  frequency.  The  open  antenna  is  employed  to 
receive  the  undesired  signals  and  by  adjusting  the  coup- 
ling between  L^  and  Z.,  the  interfering  signals  received 
on  the  coil  antenna  may  be  balanced-out  by  the  signals 
received  on  the  open  antenna.  A  shift  in  phase  of  180 
degrees  between  the  interfering  signal  received  in  the 


coil  antenna  and  that  received  in  the  open  antenna  may 
be  accomplished  by  turning  the  coil  antenna  180  de- 
grees and  smaller  variations  in  phase  between  the  same 
signals,  received  on  the  coil  and  the  open  antenna,  are 
secured  by  detuning  the  open  antenna,  causing  the  cur- 
rent either  to  lead  or  lag  the  induced  voltage.  The 
amplitude  of  the  signals  received  on  the  open  antenna 
must  be  sufficient  to  balance  the  signals  received  on  the 
coil  antenna,  even  when  the  open  antenna  is  slightly  de- 
tuned. 

If  the  combination  coil  and  open  antenna  have  been 
previously  calibrated  by  locating  a  station  whose  direc- 
tion is  known,  it  is  possible  to  determine  the  absolute 
direction  of  other  stations  by.  rotating  the  coil  to  the 
position  of  maximum  or  minimum  signal  strength. 

Coil  antennae  have  proved  useful  in  eliminating 
static  interference,  especially  on  the  shorter  wave 
lengths  and  when  the  conditions  are  such  that  a  high 
open  antenna  becomes  charged  to  high  potentials. 

METHODS  OF  TUNING 

The  main  object  of  tuning  the  circuits  of  a  radio 
receiver  is  to  reduce  the  impedance  of  the  circuits  to  a 
minimum  value  for  the  signals  to  be  received  and  to 
produce  a  high  impedance  for  all  other  frequencies.  As 
will  be  pointed  out  in  the  following  paragraphs,  the 
above  objects  are  much  easier  to  obtain  with  continu- 
ous waves  than  with  damped  waves.  Radio  receivers 
must  provide  a  means  for  loading  the  antenna,  by  in- 
serting inductance  so  as  to  cover  a  large  range  of  wave 
lengths.  The  best  arrangement  is  one  in  which  a  large 
inductance  in  series  with  a  variable  air  condenser  is 
placed  in  the  antenna  circuit.  This  arrangement  per- 
mits a  high  value  of  L/C  which  insures  a  sharper  re- 
sonance curve,  or  in  other  words  a  higher  ratio  of  the 
impedance  offered  at  other  frequencies  to  the  impedance 
at  the  resonance  frequency.  Such  a  circuit  is  resonant 
to  only  one  frequency,  while  circuits  employing  con- 
densers in  parallel  to  the  inductance  may  be  resonant 
to  several  frequencies. 

The  use  of  loosely  coupled  secondary  circuits  tuned 
to  the  same  frequency  as  the  antenna  circuit.  Fig.  2,  is 
;i  great  advantage,  especially  when  continuous  waves 
r:re  used.     For  continuous  waves  the  only  current  ex- 

\  /  Small  Value  of  K 


Secondary  Circuit 
FIG.    2 — INDUCTIVELY    COUPLED    RECEIVING    CIRCUIT 

isting  in  both  primary  and  secondary  circuits,  after  a 
few  cycles  have  reached  the  antenna,  is  the  forced  con- 
tinuous current  resulting  from  the  continuous  received 
voltage.  The  resonance  curve  of  a  receiver  with  a 
tuned  secondary  circuit  for  continuous  waves  is  found 
by  taking  the  product  of  the  ordinates  of  the  resonance 


138 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


curves  of  the  antenna  circuit  and  secondary  circuit. 
The  sharpness  of  tuning  or  selecting  is,  therefore, 
greatly  increased  by  the  use  of  a  loose  coupled,  tuned 
secondary  circuit,  as  compared  to  the  selectivity  ob- 
tained with  a  single  tuned  circuit.  In  the  resonance 
curve  referred  to,  the  ordinates  represent  the  received 


FIG.    3 — SECONDARY   CIRCUIT  OF   RECEIVING   SYSTEM 

current  and  the  abscissae  the  frequency  of  the  im- 
pressed voltage. 

The  waves  radiating  from  a  spark  transmitter  con- 
sist of  a  number  of  damped  wave  trains.  The  initial 
amplitude  of  each  wave  train  from  a  spark  transmitter 
is  the  greatest  and  the  current  falls  to  zero  after  a  rela- 
tively few  cycles.  The  spark  signal  consists  of  a 
number  of  these  short  waves  trains,  and  there  is  a  trans- 
ient current  at  ever)'  spark  discharge  of  the  transmitter. 
Therefore,  there  are  usually  two  currents  induced  in  the 
receiving  antenna,  one  of  the  impressed  frequency  and 
decrement  and  the  other  the  natural  frequency  and  de- 
crement of  the  receiving  antenna.  Since  the  secondary 
circuit  is  tuned  to  the  same  frequency  as  the  antenna 
circuit,  the  natural  oscillations  of  the  antenna  will  in- 
duce a  current  in  the  secondary,  even  if  the  impressed 
voltage  produces  no  appreciable  current  in  the  second- 
ary circuit. 

Coupled  circuits  have  been  found  to  improve  the 
selectivity  of  receivers  for  spark  reception  materially. 
However,  the  coupling  cannot  be  made  as  loose  as  for 
continuous  waves,  without  a  loss  of  signal  strength. 
Extremely  loose  coupling  increases  the  sharpness  of 
tuning  without  materially  sacrificing  signal  strength,  if 
the  signals  are  not  too  highly  damped  and  if  the  resist- 
ance of  the  secondarj'  circuit  is  not  too  high. 

DETECTORS 

The  currents  induced  in  radio  receivers  are  usually 
of  small  amplitude,  hence  only  very  sensitive  apparatus 
can  be  used  for  their  detection.  Various  devices  have 
been  used  for  detection,  such  as  the  coherer,  "barreter" 
and  thermal  detectors.     Several  forms  of  magnetic  de- 


FIC.   4 — THE   FLEMING   VALVE  OR   TWO   ELECTRODE   V.-VCri'M    TI'BE 
RECEIVING  CIRCUIT 

tectors  have  been  developed  and  used  to  a  certain  ex- 
tent. Electrolytic  rectifiers,  such  as  Prof.  Fessenden's 
liquid  barreter,  were  used  until  the  introduction  of 
crystal  detectors  or  rectifiers. 

There  are  a  number  of  crystaline  substances  which, 
when  in  contact  with  a  metal  or  another  crj'stal,  have  a 


much  higher  resistance  for  an  e.m.f.  in  one  direction 
across  the  contact  than  for  the  same  value  of  the  e.m.f. 
in  the  reversed  direction  and,  therefore,  conduct  uni- 
laterly.  It  is  evident  that  a  rectifier  connected  in  a  cir- 
cuit as  shown  in  Fig.  3,  at  d,  will  cause  a  charge  to  ac- 
cumulate on  the  condenser  C„  when  an  alternating  cur- 
rent is  flowing  in  the  circuit  LC.  If  the  alternating 
current  is  of  radio  frequency  and  is  interrupted  at  an 
audible  rate,  or  modulated  by  the  voice  as  in  radio  tele- 
phony, the  simple  rectifier  will  cause  the  charge  on  C^ 
to  vary  with  the  amplitude  of  the  radio  frequency  cur- 
rent. Current  flows  through  the  telephones,  as  a  result 
of  the  voltage  on  C„  and  is  proportional  to  this  voltage. 
Several  forms  of  crystal  detectors  are  in  use  at  the 
present  time  for  damped  wave  reception,  some  of  which 
are  very  sensitive. 

The  Fleming  valve,  a  two  electrode  vacuum  tube 
containing  a  negative  electrode,  consisting  of  a  heated 
filament,  and  a  positive  electrode  of  cylindrical   form 


Negative  1  Positive 

FIG.    5 — CHARACTERISTIC  CURVES    OF   A    THREE   ELECTRODE  VACUUM 
TUBE 

arranged  in  a  circuit,  as  shown  in  Fig.  4,  was  used  by 
the  Marconi  Company  as  a  detector.  While  probably 
no  more  efficient  than  some  crystals  the  Fleming  valve 
is  stable  and  does  not  require  frequent  adjustment.  The 
current  flows  through  the  Fleming  valve  from  the  cylin- 
drical electrode  to  the  heated  filament.  However,  the 
flow  is  possible  only  through  the  movement  of  nega- 
tively charged  electrons,  emitted  by  the  hot  filamenl,  to 
the  cylindrical  electrode.  A  two  electrode  valve  is 
therefore,  a  perfect  rectifier  when  highly  evacuated. 

The  three  electrode  vacuum  tube,  invented  by  Dr. 
De  Forest,  has  replaced  all  other  types  of  detectors,  ex- 
cept in  places  where  the  installation  is  not  of  sufficient 
importance  to  warrant  the  extra  cost  of  the  batteries  re- 
quired for  heating  the  filament,  and  of  the  necessarj'  ap- 
paratus for  charging  the  batteries. 

In  order  to  bring  out  the  relative  merits  of  the 
various  schemes  for  operating  the  three  electrode  tube 


March,   1921 


THE   ELECTRIC  JOURXAL 


139 


as  a  detector,  it  is  necessary  to  refer  to  a  characteristic 
curve  of  plate  current  vs.  grid  potential  and  grid  cur- 
rent vs.  grid  potential,  Fig.  5.  To  function  as  a  de- 
tector, the  three  electrode  tube  must  be  the  equivalent 
of  a  rectifier,  or  must  be  able  to  translate  a  train  of 
radio  frequency  waves  into  a  single  variation  of  current 
in  the  indicating  device,  which  is  usually  a  telephone 
receiver.  A  three  electrode  tube  connected  to  a  circuit 
in  which  radio  frequency  oscillations  exist,  as  shown  in 
Fig.  6,  will  act  as  a  detector,  if  the  alternating  voltage 


PUte  B.1' 

L.|,|- 

Filament  Battery 
FIG.    6 — CONNECTIO.VS    FOR    USING   THE   THREE   ELECTRODE    VACUUM 
TUBE   -\S   A   Sl.MPLE   DETECTOR 

acting  on  the  grid  causes  a  larger  increase  in  the  plate 
current  on  one-half  cycle  than  the  corresponding  de- 
crease on  the  other  half  cycle.  This  would  be  the  case 
if  a  steady  negative  grid  voltage  e^  were  impressed  on 
the  grid  in  Fig.  5  and  the  alternating-current  voltage  V-^ 
impressed  on  the  grid  caused  a  current  variation  be- 
tween the  limits  i^  and  i,-  Since  the  steady  plate  cur- 
rent would  be  i,  it  is  evident  that  a  net  increase  in  the 
plate  current  will  result,  due  to  the  impressed  alternat- 
ing-ciirrent  voltage. 

A  more  efficient  method  of  employing  the  tube  as  a 
detector  is  to  make  use  of  its  amplifying  properties. 
Since  a  certain  change  in  voltage  applied  to  the  grid  will 
cause  a  greater  change  in  the  plate  current  than  would 
result  for  the  same  change  in  voltage  on  the  plate,  the 
tube  will  function  virtually  as  a  voltage  amplifier.  The 
ratio  of  the  change  in  plate  voltage  necessary  to  cause 
the  same  change  in  plate  current,  as  is  produced  by  a 
given  change  in  grid  voltage,  is  called  the  voltage  ampli- 
fication factor  of  the  tube.  If  a  tube  is  connected  as 
shown  in  Fig.  7  to  a  circuit  in  which  radio  frequency 
current  is  flowing,  and  the  steady  potential  on  the  grid 
is  fixed  at  a  value  e„,  Fig.  5  (more  positive  than  the 
negative  end  of  the  filament,  for  high  vacuum  tubes) 
the  condenser  C„  will  be  charged  by  the  rectified  current 
resulting  from  the  unilateral  characteristic  of  the  grid 
current,  grid  voltage  curve.  The  charge  on  the  con- 
denser will  be  such  that  the  grid  potential  is  made  more 
negative  with  respect  to  the  filament  and  the  plate  cur- 
rent is  decreased.  The  plate  current  returns  to  the 
normal  value  when  the  charge  on  C„  leaks  off  through 
r.  In  this  case  there  is  both  rectification  and  amplifica- 
tion. 

A  much  greater  amplification  of  the  received  sig- 
nals can  be  obtained  by  use  of  the  regenerative  circuits, 
invented  by  Mr.  E.  H.  Armstrong.  The  simplest  form 
of  the  regenerative  circuit  is  shown  in  Fig.  8.  In  this 
arrangement  the  plate  circuit  is  coupled  to  the  grid  cir- 


cuit by  the  mutual  inductance  between  L,  and  L^.  The 
radio  frequency  voltage  impressed  on  the  grid  causes  a 
radio  frequency  current,  as  well  as  the  audio  frequency 
current,  to  flow  in  the  plate  circuit.  A  condenser  C^  is 
used  to  by-pass  the  radio  frequency  current  around  the 
telephone  receivers.  The  inductance  L^  is  too  small  to 
be  taken  into  account  for  audio  frequencies.  The  radio 
frequency  current  in  the  grid  circuit,  reinforced  by  the 
plate  current  due  to  the  mutual  inductance  Mi  and  con- 
denser C2,  accumulates  a  final  charge  proportional  to 
the  final  amplitude  of  the  current  in  the  grid  circuit. 
The  mutual  inductance  A/ ^  may  be  sufficient  to  feed 
back  enough  energy  to  the  grid  circuit  to  cause  the  cur- 
rent to  continue  to  oscillate  in  the  circuit  L^C^.  For 
short  wave  lengths  Cj  may  be  omitted  and  the  circuit 
tuned  by  means  of  a  variable  inductance  with  the 
capacity  of  the  coils  and  tube  alone. 

Another  form  of  regenerative  circuit,  which  is 
suited  for  receiving  circuits  for  short  waves  is  shown 
in  Fig.  9.  The  variable  inductance  L^  is  placed  in  the 
plate  circuit.  The  voltage  produced  across  the  induct- 
ance L3  causes  a  current  to  flow  through  the  capacity 
between  the  elements  of  the  tube,  (shown  dotted)  which 
produces  a  voltage  on  the  grid  to  reinforce  the  original 
voltage.  The  smaller  the  value  of  C,  the  more  pro- 
nounced is  the  effect. 

The  regenerative  vacuum  tube  circuits  are  the 
simplest  and  most  efficient  means  at  the  present  time  for 
the  reception  of  damped  wave  signals  if  extreme  ampli- 
fication is  unnecessary.  Tubes  containing  a  consider- 
able amount  of  gas  are  more  sensitive  detectors  than 
tubes  having  a  high  vacuum.  The  presence  of  gas 
causes  the  tube  to  have  a  lower  impedance  due  to  the 
positive  ions  formed,  which  tend  to  neutralize  the  space 
charge  of  the  electrons.  For  a  definite  plate  voltage, 
the  plate  current  in  a  high  vacuum  tube  is  usually 
limited  by  the  neutralizing  effect  of  the  negative  charges 
of  the  electrons  on  the  field  from  the  positive  plate,  in 
the  space  near  the  filament.  Therefore  increasing  the 
filament    temperature    and    the    number    of    electrons 


7 — CONNECTIONS     1  OR    USI 
TUBE   FOR    SIMULTANEOUS 


:g   the   three  electrode  vacuum 
amplifving  and  rectifying 


emitted  from  the  filament,  will,  not  cause  more  electrons 
to  be  drawn  from  the  filament  to  the  plate.  If  there  is 
gas  in  the  tube,  positive  ions  are  formed  between  the 
grid  and  plate  and  these  combine  with  electrons  to  re- 
duce the  space  charge,  thus  permitting  a  greater  flow 
of  electrons  to  the  plate.  The  grid  which  is  placed  be- 
tween the  filament  and  the  plate  regulates  the  passage 
of  the  electrons  through  it.  If  the  grid  is  negative,  the 
passage  of  the  electrons  through  it  is  retarded,  and  also 
some  of  the  positive  ions  are  drawn  to  the  grid,  which 


I40 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


may  result  in  the  neutralization  of  the  space  charge  to 
a  lesser  degree  and,  therefore,  a  reduction  in  the  flow 
of  electrons  to  the  plate,  due  to  both  effects.  The  pres- 
ence of  positive  ions  may  also  result  in  a  grid-current, 
grid-voltage  characteristic  which  is  more  efficient  for 
rectification   than   can  be  obtained  in  the  high  vacuum 


FIG.   8 — ARMSTRONX    REGENERATIVE    CIRCUIT 

For  simultaneous  amplifying  and  rectifying 

tubes.  The  unilateral  conductivity  between  grid  and 
filament  is  greater  when  positive  ions  are  present  in  the 
right  amount. 

Gaseous  or  soft  tubes,  while  they  are  remarkably 
sensitive  as  detectors,  require  a  source  of  variable  plate 
voltage  and  filament  current.  The  adjustments  usually 
have  to  be  made  frequently  on  account  of  the  heating  of 
the  gas  by  the  hot  filament,  etc.  It  has  not  been  possible 
to  make  gaseous  tubes  containing  a  uniform  amount  of 
gas,  therefore,  such  tubes  have  to  be  carefully  selected 
or  many  of  them  may  be  worthless.  It  is  doubtful  if 
soft  tubes  are  to  be  recommended  for  practical  use  in 
any  case,  because  of  the  necessary  adjustments.  The 
hard  tube  is  a  less  sensitive  detector  which  requires  no 
attention,  gives  uniform  results  at  all  times,  and  is  inter- 
changeable with  similar  tubes  without  making  adjust- 
ments, and  is  to  be  preferred. 

In  addition  to  the  amplification  resulting  from  the 
use  of  regenerative  vacuum  tube  circuits,  a  great  in- 
crease in  selectivity  is  obtained,  due  to  the  reduced 
damping  of  the  wave  length  to  which  the  circuit  is 
tuned.  The  advantages  of  using  continuous  waves  for 
radio  communication  from  the  standpoint  of  receiving 
circuits  has  been  pointed  out.  Most  of  the  older 
methods  of  detecting  continuous  waves,  however,  are 
unsuited  for  practical  work.  Some  of  the  devices 
which  have  been  used  are  the  tikker,  tone  wheel  and 
several  schemes  for  causing  the  incoming  signal  to  con- 
trol a  local  source  of  audio  frequency  current  through 
the  telephones.  All  of  these  schemes  require  apparatus 
in  addition  to  the  detector.  For  example  the  tikker 
and  tone  wheel  require  driving  motors,  while  the  last 
mentioned  scheme  requires  a  source  of  local  audio  fre- 
quency current.  If  continuous  wave  telegraphy,  with 
all  its  advantages  over  other  systems,  is  to  become 
popular,  a  simple  and  efficient  detector  is  necessary  and 
this  is  available  in  the  form  of  the  oscillating  vacuum 
tube.  The  maintenance  cost  is  no  more  than  for  a 
simple  regenerative  spark  receiver  or  any  vacuum  tube 
detector.  As  to  the  apparatus  required  and  the  opera- 
tion, it  is  practically  the  same  as  for  efficient  spark  re- 
ception. 


While  the  use  of  the  vacuum  tube  as  a  beat  or  self- 
heterodyne  detector  is  due  to  Major  Armstrong,  the 
method  of  beat  reception  of  continuous  waves  was  in- 
vented by  Prof.  Fessenden  before  the  invention  of  the 
vacuum  tube.  Prof.  Fessenden  combined  with  the  in- 
audible frequency  current  being  received,  a  current 
from  a  local  generator,  having  a  frequency  differing 
from  the  signal  current  frequency  by  the  number  of 
cycles  required  to  give  the  desired  audio  frequency  note. 
The  combined  currents  were  passed  through  a  telephone 
receiver  which  produced  distortion,  or  one  which  had 
no  permanent  magnet.  The  practical  type  first  used  had 
?  core  of  iron  wires  in  the  winding  through  which  the 
current  passed  and  instead  of  an  iron  diaphragm  a  mica 
diaphragm  carrying  a  coil  of  fine  wire  was  used. 

It  is  evident  that,  if  the  combined  currents  are  rec- 
tified by  any  method  and  the  current  passed  through  a 
telephone  receiver,  an  audio  frequency  note  of  the  same 
frequency  as  the  beats  will  be  heard.  The  three  elec- 
trode vacuum  tube  may  be  used  to  generate  the  local 
radio  frequency  current  which  beats  with  the  received 
signals  and  to  detect  the  beat  note  at  the  same  time,  and 
when  functioning  as  a  generator  and  heterodyne  de- 
tector it  amplifies  the  signals  as  well,  due  to  the  coup- 
ling between  the  plate  and  grid  circuits.  Armstrong 
found  that  the  amplification  secured  with  the  self- 
heterodyne  as  compared  with  a  simple  chopper  circuit 
was  about  5000  times*.  The  efficiency  of  a  self-hetero- 
dyne vacuum  tube  depends  upon  the  amplitude  of  the 
local  oscillations,  which  is  easily  controlled  by  means 
of  a  variable  coupling  between  the  plate  and  grid  cir- 
cuits. The  secondary  circuit  of  the  receiver  is  usually 
the  circuit  which  determines  the  frequency  of  the  local 
current  and  in  order  to  obtain  a  frequency  to  give  a 
beat  note  suitable  for  aural  reception  of  long  wave 
lengths,  the  secondary  must  be  detuned  appreciably. 
For  long  wave  lengths,  such  as  are  used  for  trans- 
oceanic communication,  it  is  advisable  to  use  only  suffi- 
cient coupling  between  the  grid  and  plate  circuits  to  ob- 
tain amplication  and  to  use  separate  heterodyne  genera- 


FIG.    9— REGENERATIVE  CIRCUIT  SUITED  FOR  RECEIVING    SHORT    WAVES 

tors  for  supplying  the  local  current.  The  tuned  circuit 
to  which  the  detector  is  connected  can  then  be  tuned  ex- 
actly to  the  incoming  signals. 

The  vacuum  tube,  used  as  a  detector  of  damped  or 
modulated  waves,  as  well  as  all  rectifying  detectors, 
gives  a  signal  in  the  telephone  which  is  proportional  to 
the  square  of  the  voltage  impressed  on  the  grid.     But 


*E.  H.  Armstrong,  Proc.  I.  R.  E.  1917. 


April,  192 1 


THE  ELECTRIC  JOURNAL 


141 


when  the  vacuum  tube  is  used  as  a  self-heterodyne  de- 
tector or  when  a  separate  heterodyne  generator  is  used 
with  any  detector,  the  response  is  proportional  to  the 
first  power  of  the  impressed  signal  voltage.  This  char- 
acteristic renders  this  method  of  detection  equally  effi- 
cient for  weak  or  strong  signals. 

AMPLIFIERS 

There  have  been  many  attempts  mac^e  to  develop 
suitable  apparatus  for  amplifying  weak  alternating  cur- 
rents, or  in  other  words  to  control  considerable  power 
by  a  weak  current.  For  telephone  signals,  it  is  neces- 
sary to  have  the  controlled  current  follow  exactly  the 
variations  of  the  controlling  current.  The  "Brown 
Relay"  and  the  "Schreeve  Repeater"  have  been  fairly 
successful  and  such  devices  still  have  their  application. 
The  three  electrode  vacuum  tube,  however,  is  rapidly 
replacing  all  other  devices  as  an  amplifier  of  alternating 
current  and,  in  some  instances,  it  is  being  used  to  re- 
place ordinary  relays  in  direct-current  telegraph  lines. 
Amplifiers  may  be  used  to  increase  the  sensitiveness  of 
a  receiving  set  either  by  amplifying  the  radio  frequency 
signal  current  before  it  is  rectified  or  by  amplifying  the 
audio  frequency  current  resulting  from  the  rectification. 


Transformer 
FK;.     10 — CONNKCTI 


Transformer  L 
FOK    tASCADK 


Mli-IFIIATION 


The  tubes  are  usually  connected  in  cascade  and  the  plate 
and  grid  circuits  connected  through  a  transformer,  as 
shown  in  Fig.  10. 

In  radio  receiving  sets  it  is  not  practical  to  use 
more  than  two  efficient  stages  of  audio  frequency  am- 
plification when  receiving  by  ear,  due  to  the  fact  that 
some  nearby  spark  transmitter  may  start  up  on  the  wave 
length  to  which  the  receiver  is  tuned  and  cause  con- 
siderable discomfort  to  the  operator.  Static  and  other 
disturbances  are  also  amplified  to  such  an  extent,  when 
extreme  audio  frequency  amplification  is  used,  that  the 
ear  is  quickly  fatigued  and  weak  signals  cannot  be  read 
as  easily  as  if  both  the  noise  and  signal  were  weaker. 

In  continuous  wave  systems  with  heterodyne  re- 
ception it  becomes  possible  to  use  amplifiers  that 
amplify  only  one  frequency  and,  therefore,  very  great 
selectivity  is  obtained  and  the  ratio  of  the  noise  due  to 
static  induction  and  noises  inherent  in  the  amplifier 
itself  are  greatly  reduced  in  c()mj)arison  to  the  signal  ob- 
tained. 

For  the  operation   of  loud   speaking  telephone   re- 


ceivers, which  require  considerable  power  for  proper 
operation,  several  tubes  may  be  connected  in  parallel. 
Tubes  capable  of  handling  several  watts  in  the  plate  cir- 
cuit are  desirable  in  connection  with  instruments  for 
use  in  large  halls  and  in  the  open  air. 

Radio  frequency  amplification  may  be  used  to  ad- 
vantage in  case  the  signals  are  weak  and  the  amplifica- 
tion obtained  with  two  stages  of  audio  frequency  is  not 
sufficient.  Since  a  vacuum  tube  detector,  and  in  fact 
most  detectors  of  damped  waves,  gives  an  audio  fre- 
ijuency  signal  approximately  proportional  to  the  square 
of  the  impressed  voltage  for  weak  signals,  it  is  obvious 
that  the  efficiency  of  the  receiving  system  is  greater  if 
the  amplification  is  accomplished  at  radio  frequency. 
The  detector  acts  as  a  limiting  device  to  limit  the 
strength  of  the  audio  frequency  signal,  so  that  signals 
cannot  increase  too  much,  but  weak  signals  are  brought 
nearer  to  the  same  strength  as  the  strong  ones  in  tele- 
phones. By  using  three  or  four  stages  of  radio  fre- 
quency amplification  with  a  detector  in  connection  with 
the  coil  antenna,  it  is  possible  to  use  a  very  small  coil 
antenna,  which  can  be  rotated  for  the  purpose  of  elimi- 
nating interference  or  for  direction  finding,  and  to  ob- 
tain signals  of  strength  equal  to  those  received  on  a 
large  open  antenna  with  a  detector  and  two  stages  of 
audio  frequency  amplification. 

A  great  advantage  of  radio  frequency  amplification 
i^.  that  the  number  of  stages  or  amount  of  amplification 
is  not  limited  by  noises  inherent  in  the  amplifier  and  by 
low  frequency  induction  noises  picked  up  by  the  receiv- 
ing set,  due  to  the  fact  that  the  amplifier  is  capable  of 
amplifying  only  high  frequencies. 

Tubes  having  a  high  vacuum  or  hard  tubes  are  re- 
quired for  use  with  multi-stage  amplifiers,  as  the  char- 
acteristics of  the  tubes  must  be  known  and  be  unifonn, 
and  it  is  practically  impossible  to  keep  six  or  seven  soft 
tubes  in  adjustment  long  enough  to  receive  a  message. 

It  is  desirable  to  have  the  internal  plate  circuit  im- 
pedance of  amplifier  tubes  low  and  the  grid  to  filament 
impedance  high,  on  account  of  the  apparatus  which 
must  be  associated  with  the  tubes.  The  transformers 
for  connecting  the  tubes  in  cascade  can  be  made  more 
efficient  the  lower  the  plate  circuit  impedance,  and 
the  voltage  can  be  stepped  up  more  in  the  transformer 
with  higher  grid  to  filament  impedance.  In  general 
low  plate  circuit  impedance  results  in  a  low  voltage  am- 
plification factor  but  it  is  difficult  to  utilize  the  full  volt- 
age amplification  of  tubes  having  an  impedance  higher 
than  approximately  40000  ohms  in  the  plate  circuit,  as 
efficiently  as  for  tubes  having  a  lower  plate  circuit  im- 
pedance. 


Q.  A.  BRACKET  T 


FOR  NEARLY  20  years  radio  communication  has 
been  centered  around  the  original  system  of 
Marconi,  wherein  the  discharge  of  a  highly 
charged  condenser  across  a  spark  gap  was  utilized  to 
set  up  high  frequency  oscillations  in  a  radiating  circuit. 
Improved  as  it  was  by  many  eminent  engineers  as  the 
vears  went  by,  it  remained  always  a  system  emitting 
trains  of  waves  that  were  more  or  less  highly  damped 
instead  of  continuous.  Engineers  soon  came  to  realize 
how  much  superior  the  effectiveness  of  undamped  or 
continuous  waves  would  be  if  only  a  satisfactory  source 
were  available.  The  search  for  such  a  source  developed 
ultimately  along  three  lines,  viz.  the  arc,  the  high  fre- 


however,  for  Elihu  Thomson,  in  1892,  to  discover  the 
fact  that,  under  certain  conditions,  the  arc  could  be 
made  to  oscillate  even  though  supplied  with  direct 
current.  From  this  Duddell  in  England,  about  1900, 
developed  the  so-called  "singing"  or  "talking"  arc  which 
was  a  favorite  laboratory  ctiriosity  of  a  decade  ago. 
It  was  learned  that  if  a  direct-current  arc,  supplied 
from  a  source  of  constant-current  characteristic,  was 
shunted  by  a  capacity,  or  a  capacity  and  inductance  in 
series,  an  alternating  current  would  flow  in  the  shunt 
circuit.  This  was  due  to  the  alternate  charging  and  dis- 
charging of  the  condenser  as  the  arc  voltage  rose  and 
fell,  due  to  the  negative  characteristic  of  the  arc  as  the 


FIG.    I — 500  K\V 

With  closed  m 
quency  alternator  and  the  vacuum  tube.  Thf  latter 
came  into  the  field  only  in  recent  years  and  can  hardly 
as  yet  be  considered  commercialized.  The  high-fre- 
quency alternator  has  taken  from  ten  to  fifteen  years  to 
perfect  and  even  now  is  considered  suited  only  to  extra 
high  power  stations  operating  on  a  fixed  wave  length. 
The  great  burden  of  continuous  wave  radio  communi- 
cation has,  therefore,  fallen  upon  the  arc,  because  of  its 
feasibility  in  moderate  sizes  and  the  readiness  with 
which  it  can  be  adjusted  to  operate  at  various  wave 
lengths. 

The  fact  than  an  electric  arc  functions  like  a  nega- 
tive resistance  i.e.,  that  its  voltage  drop  decreases  with 
increase  of  arc  current,  has  been  known  since  the 
earliest  days  of  the  illuminating  arc  lamp.    It  remained. 


.\RC  CONVERTER 

agnetic  circuit, 
condenser  alternately  robbed  it  of  current  and  then  re- 
turned it  superimposed  upon  the  normal  arc  current. 
The  frequency  of  these  alternations  was  determined  by 
the  constants  of  the  shunt  circuit  and  was  compara- 
tively low,  giving  rise  to  the  term  "singing  arc"  as  the 
current  fluctuations  in  the  arc  flame  gave  rise  to  an 
audible  sound  of  the  same  pitch. 

When  the  circuit  was  properly  adjusted  the  arc  re- 
mained in  a  very  sensitive  state,  wherein  any  disturb- 
ance in  the  circuit  would  be  reproduced  audibly  by  the 
arc  flame.  In  this  way,  the  arc  could  be  made  to  re- 
produce music  or  speech  directed  into  a  microphone 
associated  with  the  arc  circuit  in  any  one  of  various 
ways.  As  stated  above,  this  was  a  very  interesting 
laboratory   experiment,   but  had  little   practical   utility 


April,   1921 


THE   RLHCIRIC  JOUKN.U. 


143 


except  as  a  novelty  for  advertising  purposes.  It  was 
for  instance,  utilized  in  New  York  in  1907  in  connection 
with  the  ill-fated  "Cahill  Telharmonium"  method  of 
electrically-creating  and  distributing  music.  In  the  con- 
cert hall  at  39th  Street  and  Broadway,  after  the  regular 
concert  program  using  a  form  of  telephone  receiver  and 
horn  as  a  reproducer,  the  final  numbers  were  heard 
coming  from  the  flame  of  an  arc  lamp  overhead.  The 
ciTect  was  indescribably  weird  and  mysterious  to  the 
average  listener.  It  was  when  hearing  a  description  of 
such  a  talking  arc  that  Mark  Twain  is  alleged  to  have 
said  that  he  could  see  in  his  mind's  eye  the  King  of 
England  driving  up  the  street  while  all  the  arc  lamps 
along  the  route  played  "God  save  the  King." 

.\lthough    many   engineers   and   physicists   experi- 
mented with  the  oscillating  arc,  only  oscillations  of  low 


FIG.    2 — 30   KW  ARC  CON\'ERTER 

With  open  magnetic  circuit. 

frequency  antl  feeble  intensity  were  (obtained.  It  re- 
mained for  Valdemar  Poulsen  of  Denmark  to  make  the 
next  big  step  in  development  which  took  the  oscillating 
arc  out  of  the  class  of  laboratory  curiosities  and  [ilaced 
it  firmly  among  valuable  utilities. 

In  1902,  Poulsen  announced  his  discovery  of  the 
possibility  of  producing  oscillations  of  high  frecjiiencx 
from  an  arc  in  an  atmosphere  of  hydrogen.  The  use 
of  a  strong  transverse  magnetic  field  across-the  arc  and 
the  artificial  cooling  of  the  anode  were  other  iniporlanl 
refinements  of  his  design.  For  years,  how-ever,  tiie  arc 
was  unable  to  win  its  way  in  competiti(jn  jvith  the  al- 
ready established  spark  system.  There  \vere  various 
reasons  for  this.  In  the  first  place,  the  demand  at  that 
time  was  for  comparatively  small  radio  sets  -operating  at 
short  wave  lengths.  In  this  field  the  arc  is  not  at  its 
best,  as  it  is  unstable  at  short  wave  lengths  and  in  small 
sizes.  Thus  its  most  serious  difficulties  were  encoun- 
tered first.     It  took  time  to  develop  the  arc  to  the  large 


|]owers  now  common  and  to  create  the  demand  for 
them. 

The  main  reason,  however,  why  the  arc  was  slow 
in  coming  into  use  was  that  the  signals  were  entirely 
inaudible  with  the  existing  types  of  receiving  apparatus, 
unless  interrupters  were  used  to  break  up  the  wave 
trains  into  audible  frequencies.  It  was  almost  impossible 
to  construct  an  interrupter  that  would  handle  satisfac- 
torily the  power  at  the  transmitter  so  that  any  receiving 
set  could  listen,  although  so  called  "choppers"  were  de- 
veloped and  used  with  small  sets  or  at  reduced  power. 
Prof.  Pedersen,  Poulsen's  co-worker  at  Copenhagen,  de- 
\  eloped  an  interrupter  method  of  receiving,  called  a 
"tikker",  that  was  the  most  satisfactory  method  in  use 
for  many  years,  but  in  comparison  with  modern 
methods  it  was  quite  inefficient. 

About  this  time.  Prof.  Fessenden  invented  what 
b.e  called  the  "heterodyne  method"  of  reception,  which 
was  destined  to  prove  the  ultimate  solution  of  the  prob- 
lem and  make  practicable  the  use  of  the  arc  and  other 
methods  of  undamped  or  continuous  w-ave  transmission. 
This  consisted  in  generating  locally  at  the  receiving  sta- 
tion a  feeble  oscillating  current  of  an  adjustable  fre- 
quenc}-  close  to  that  to  be  received,  and  superimposing 
the  two  frequencies,  thus  causing  interference  beats  be- 
U\een  them,  when  rectified,  of  any  desired  audio  fre- 
(|uency.  This  method,  however,  could  not  be  used  for 
lack  of  a  cheap  and  convenient  source  of  local  oscilla- 
tions. Fessenden  in  his  experiments  used  one  of  the 
(,nly  two  high  frequency  alternators  built  at  that  time.     ^ 

It  was,  therefore,  not  until  1912  when  Armstrong, 
in  this  counti-y,  discovered  the  method  of  generating 
high-frequency  currents  by  causing  a  De  Forest  audion 
1(1  oscillate  through  interlinking  its  plate  and  grid 
circuits,  that  the  heterodyne  method  became  available 
tor  practical  use.  Now  it  is  an  indispensable  part  of  all 
modern  commercial  receiving  .sets. 

At  the  time  when  the  oscillating  audion  was  de- 
veloped for  reception,  the  oscillating  arc  had  been  per- 
fected and  huill  in  large  sizes  until  today  most  of  the 
large  stations  of  the  world  are  equipped  with  the  arc 
transmitter.  Likewise  some  of  the  larger  ocean  liners 
and  I'nited  States  Naval  craft  employ  arc  sets  of 
moderate  size  to  ensure  long  distance  communication 
such  as  c(juld  not  be  obtained  from  the  spark  sets. 

The  modern  arc  transmitter  consists  fundamentally 
of  a  direct-current  arc.  operated  in  an  atmosphere  of 
Indrogen  in  a  strong  transverse  magnetic  field,  and 
"hunted  by  an  oscillatory  circuit  containing  inductance 
;:nd  capacitv.  While  the  latter  may  form  a  local  cir- 
cuit inductively  coupled  to  the  radiating  circuit,  it  is  at 
jiresent  more  common  to  use  the  arc  directly  in  the 
;'.ntenna.  In  such  cases  the  shunt  oscillatory  circuit 
consists  of  the  capacity  of  the  antenna  and  its  induct- 
ance, increased  liy  such  additional  loading  coils  inserted 
in  series  with  the  antenna  as  may  be  necessary  to 
obtain  the  desired  wave  length.  The  latter  is  deter- 
mined by  the  constants  of  the  shunt  oscillating  circuit. 


144 


THE   ELECTRIC  JOURNAL 


Vol.  XVIIl,  No.  4 


The  transverse  magnetic  field  may  be  shunt  or 
separately  excited,  but  is  more  usually  obtained  from 
coils  in  series  with  the  direct-current  supply  to  the  arc, 
which  also  may  serve  as  protective  choke  coils  to  hold 
back  the  radio  frequencies  from  the  direct-current 
generator  and  as  energy-storing  choke  coils  to  maintain 
the  supply  current  constant,  so  that  the  arc  will  oscil- 
late. Whether  the  iron  magnetic  circuit  is  open  or 
closed  is  not  vital,  provided  there  is  sufficient  field 
strength  across  the  arc,  and  depends,  therefore,  upon 
practical  questions  of  design  such  as  size,  weight,  cost 
and  ease  of  installation.  Most  of  the  small  arc  con- 
verters of  American  design  have  open  magnetic  cir- 
cuits, while  most  European  arcs  and  all  large  converters 
have  closed  magnetic  circuits.  For  use  on  small  steel 
ships,  the  closed  circuit  design  is  to  be  preferred,  as  it 
reduces  the  disturbance  of  the  ship's  compass  caused  by 
stray  flux  in  the  case  of  the  open  circuit  type. 

The  hydrogen  atmosphere  is  usually  obtained  most 
conveniently  through  the  decomposition  of  some  hydro- 
carbon, such  as  alcohol,  by  enclosing  the  arc  in  a  cham- 
ber of  some  non-magnetic  material  and  allowing  the 
hydrocarbon  to  drip  into  the  arc  at  a  suitable  rate  which 
can  be  adjusted  as  desired. 

In  order,  however,  that  the  arc  may  be  made  to 
oscillate  in  a  stable  manner  when  handling  considerable 
power,  it  is  necessary  to  keep  the  anode  cool,  and  for 
this  reason  it  is  customary  to  make  the  latter  of  hollow 
copper  and  cool  it  by  a  continual  flow  of  water  through 
it.  On  the  larger  arcs,  the  arc  chamber  and  the  anode 
and  cathode  holders  are  likewise  water  cooled,  a  small 
centrifugal  pump  being  used  to  circulate  the  water 
from  a  storage  tank.  In  this  way  much  higher  arc 
voltage  can  be  used  and  more  power  can  be  developed. 

The  cathode  is  usually  a  round  carbon  rod  which  is 
rotated  slowly  by  a  motor  through  worm  gears,  so  as  to 
make  the  burning  uniform.  As  the  oxygen  in  the  en- 
closed arc  chamber  is  rapidly  consumed  the  carbon  does 
not  necessarily  burn  away  as  in  ordinai-y  arcs,  but  may 
actually  grow  longer,  due  to  deposition  of  carbon  from 
the  hydrocarbon  atmosphere.  Usually  the  end  of  the 
cathode  develops  a  shape  like  the  head  of  a  mushroom. 

Ordinarily  the  cathode  is  grounded  directly  through 
the  arc  chamber  and  the  frame  of  the  arc  converter. 
It,  therefore,  needs  little  clearance  from  the  pole  faces. 
The  anode,  however,  is  usually  flattened  so  as  to  in- 
crease its  separation  from  the  poles  to  a  safe  amount 
for  the  voltage  involved. 

Fig.  4  shows  a  typical  diagram  of  connections  of 
an  arc  transmitter  direct  connected  to  an  antenna.  The 
direct-current  generator,  driven  by  any  convenient 
means,  delivers  current  through  the  magnet  field  coils 
FF  and  the  radio  frequency  choke  coil  RF  to  the  water 
cooled  anode  A  and  the  slowly  rotated  carbon  cathode 
C.  The  anode  A  is  connected  to  the  antenna  through 
the  loading  coil  L.  The  choke  coil  RF  may  be  dis- 
pensed with  if  the  end  turns  of  the  main  field  coils  are 


insulated  so  that  they  are  able  to  stand  the  impact 
of  the  radio  frequency  generated  by  the  arc.  The  field 
coils  and  magnet  systems  are  so  proportioned  as  to  give 
the  necessary  field  strength  at  the  arc  which  is  of  the 
order  of  20  kilogausses. 

The  antenna  capacity  and  the  loading  coil  L  in 
elfect  constitute  a  shunt  circuit  around  the  arc  and 
cause  continuous  alternating  currents  to  be  generated 
by  the  arc  of  a  frequency  determined  by  the  capacity 
and  inductance.  Changes  of  wave  length  are  easily 
made  by  changing  taps  on  the  loading  coil.  If  a  wide 
range  of  wave  lengths  is  desired,  it  may  also  be  neces- 
sary to  change  taps  on  the  magnet  field  coils  at  the  same 
time,  as  not  all  wave  lengths  require  the  same  field 
strength. 

It  is,  of  course,  impossible  to  signal  with  an  arc 
converter  by  causing  the  telegraph  key  to  interrupt  the 
power  supply,  as  in  the  case  of  spark  sets,  because  it 
would  be  necessary  to  bring  the  electrodes  together  and 


FIG.    3 — ANTENNA    LOADING    IM  II.  VSTEM 

Of  a  high   power    radio    station    cciuippid    with    arc   trans- 
mitter. 

restart  the  arc  after  each  interruption.  It  is  true  that 
something  like  this  has  been  done  successfully  in  the 
case  of  the  smaller  sets,  where  the  arc  is  restarted, 
without  moving  the  electrodes,  by  means  of  a  high-volt- 
age pilot  spark.  On  all  medium  and  large  size  arc  sets, 
however,  it  has  been  found  necessary  to  avoid  interrupt- 
ing the  arc. 

The  simplest  scheme  and  the  one  most  generally 
in  use  up  to  the  present  time  is  called  the  "compensated 
wave"  method.  This  consists  of  signaling  by  changing 
the  emitted  wave  length  slightly,  so  that  when  the  key 
is  up  the  signals  are  inaudible  or  of  noticeably  changed 
pitch  in  the  receiver.  This  is  usually  accomplished  by 
short-circuiting  a  few  turns  of  the  antenna  loading  coil 
or  of  a  coil  inductively  coupled  to  it.  The  beauty  of 
this  scheme,  from  an  operating  standpoint,  is  that  it  is 
only  necessary  to  short-circuit  a  very  small  percentage 


April,   1921 


THE   ELECTRIC  JOURNAL 


145 


of  the  total  inductance  to  cause  sufticient  change  of 
wave  length  to  give  good  signals.  This  means  that  the 
relay  key  contacts  have  to  handle  only  a  very  small  part 
of  the  total  energy;  which  makes  the  problem  of  de- 
sign much  easier.  For  instance,  if  the  incoming  wa\e  is 
of  100  000  cycles  and  a  heterodyne  receiver  is  used  to 
generate  locally  100  500  cycles,  the  signals  are  received 
as  an  audible  500  cycle  note.  It  is  only  necessary, 
therefore  for  the  sender  to  change  the  transmitted  fre- 
quency 500  cycles  or  one-half  of  one  percent  between 
signals  to  make  the  received  frequency  eciual  to  the 
locally  generated  frequency,  so  that  nothing  would  be 
h.eard  in  the  receivers,  between  the  dots  and  dashes. 
Under  these  conditions,  therefore,  the  signals  received 
would  vaiy  from  500  cycles  to  complete  inaudibility 
when  the  sending  key  was  used  to  short-circuit  only 
;'bout  one  percent  of  the  loading  inductance. 

This  compensated  wave  method  of  signaling  is 
used  on  the  great  majority  of  arc  sets  above  two  kilo- 
watts and  on   practically  all    above   50   kw.     However, 


tain,  that  in  the  near  future  radio  regulations  will  for- 
bid the  use  of  the  "compensated  wave"  method  of  send- 
ing. 

The  best  of  the  schemes  developed  is  the  "uniwave 
key",  invented  by  Lt.  \V.  A.  Eaton*  of  the  U.  S.  Navy 
;ind  manufactured  by  the  Westinghouse  Company. 
With  this  device  the  signals  sent  out  by  an  arc  station 
closely  resemble  those  from  a  large  vacuum  tube  set. 
Only  one  wave  length  is  sent  out,  no  back  wave  is  heard 
;.nd  the  harmonics  often  accompanying  the  signals  are 
much  reduced.  In  addition  the  transmitted  signals  are 
unusually  clear-cut,  as  the  sending  relay  does  not  have 
to  break  any  current  and  so  does  not  spark  at  the  con- 
tacts on  the  sending  side.  All  sparking  occurs  on  the 
dummy  antenna  or  non-radiating  side  of  the  relay 
stroke. 

The  arc  transmitter,  however,  is  not  limited  to  its 
use  in  radio  telegraphy.  As  a  generator  of  continuous 
waves  it  can  also  be  used  for  radio  telephony.  As  far 
back  ;!•;  TO07  Pduhen  himself  telephoned  from  Denmark 


I'K^    4 — TVrU  AL       LOXXECTIU.W-^ 
.\.\     ARC    TKANSMITTER    DIRrCT    COX- 
.NKl   IKl)    ni    THE    ANTENNA 


while  it  provides  a  very  attractive  method  of  signaling 
from  an  operating  standpoint  it  has  one  serious  draw- 
l<ack,  and  this  is  sufficient  practically  to  assure  the  aban- 
donment of  this  method  of  sending.  'i'his  is  due 
to  the  fact  that  it  uses  up  two  wave  lengths  for  one  sta- 
tion. Not  only  does  the  station  radiate  two  wave 
lengths,  but  it  also  sends  out  energy  at  those  instants 
when  normally  it  should  be  silent,  that  is,  between  the 
dot  and  dashes  of  the  telegraphic  signals.  To  make  it 
still  worse,  it  also  radiates  during  the  intervals  between 
messages,  that  is,  while  the  operator  is  receiving,  unless 
ilie  arc  is  stopped  entirely,  which  is  often  not  con- 
\  enient. 

For  this  reason  active  development  has  been 
carried  on  to  perfect  a  method  of  signaling  that  would 
prevent  the  arc  from  radiating  energy  except  during  the 
dot  and  dash  signals,  and  then  at  only  one  wave  length. 
The  success  of  this  development  has  made  it  almost  cer- 


'tr..    5 — ARC  WAVE  CHANGER   ANP   INPITTANrE   SYSTEM 

to  England  using  an  arc.  In  1906  the  Iniied  States 
fleet  that  made  the  famous  trip  around  the  world  was 
equipped  with  arc  type  radio  telephones.  It  is  true  that 
the  latter  were  of  early  and  crude  design  and  construc- 
tion and  did  not  give  entire  satisfaction.  They  were  later 
improved,  however,  and  a  very  workable  arc  telephone 
set  developed,  good  for  perhaps  50  miles  over  water.  As 
larger  arc  sets  were  developed,  however,  the  telephone 
application  was  lost  sight  of  for  the  reason  that  unsur- 
mountable  difficulties  were  encountered.  The  power 
was  there  of  the  kind  suited  for  radio  telephony,  but  no 
microphone  could  be  devised  delicate  enough  to  projierly 
reproduce  speech  that  could  handle  enough  current  to 
take  care  of  any  but  the  smallest  sets.  This  was  be- 
cause no  trigger  has  yet  been  devised,  for  the  arc  oscil- 
lator, equivalent  to  the  grid  of  the  vacuum  tube  oscil- 
lator. 


*Described  by  the  iiivciitcr  on  page  114  of  this  issue. 


146 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


Up  to  date  it  has  been  necessary,  in  arc  telephone 
sets,  to  have  the  microphone  modulate  the  power  direct, 
by  connecting  it  in  series  with  the  antenna  or  across  the 
terminals  of  a  coil  coupled  to  the  antenna,  or  in  some 
other  such  arrangement.  These  methods  work  well  but 
are  limited  in  power  by  the  amount  of  energy  that  the 
microphone  can  dissipate.  Development  work  is  now 
in  progress  seeking  to  perfect  some  new  method  of  tele- 
phoning with  arcs  that  will  overcome  this  difficulty. 

If  an  eiificient  and  practicable  method  of  telephon- 
ing with  an  arc  transmitter  is  developed,  the  position  of 
the  latter  will  be  greatly  strengthened,  even  in  competi- 
tion with  the  larger  size  power  tubes  we  can  forsee  in 
the  not  very  distant  future.  The  weaknesses  of  the  arc 
type  of  transmitter  are  its  lower  efficiency,  its  emission 
of  undesirable  overtones  and  its  lack  of  a  flexible  means 
of  power  control  for  telephony.  To  counterbalance  this 
it  can  rightfully  be  claimed  that  inii)roved  methods  of 
signaling   give    promise    of    eliminating    the    o\ertones, 


while  its  lower  efficiency  is  counterbalanced  by  its  low 
maintenance  expense.  As  compared  with  the  high-fre- 
i-iuency  alternator  it  is  much  cheaper  in  first  cost,  very 
much  easier  to  repair,  is  susceptible  to  easy  and  quick 
change  of  wave  length,  can  operate  at  shorter  wa\e 
lengths  and  on  smaller  antennae,  and  has  no  high-speed 
moving  parts. 

As  compared  with  the  vacuum  tube  lyi>e  of  trans- 
mitter its  maintenance  cost  is  very  much  lower,  and  it 
has  no  fragile  parts  that  require  frequent  renewals  and 
which  may  not  be  readily  available  in  remote  locations. 
It  also  is  available  in  much  larger  sizes  than  are  yet 
practicable  with  tubes. 

The  majority  of  the  large  stations  of  the  world  are 
of  the  arc  type,  such  as  those  at  Annapolis,  San  Diego 
and  Tuckerton  U.  S.  A.,  Darien  Panama,  Pearl  Harbor, 
Hawaii,  Rome,  Italy,  Lyons  France,  and  the  largest 
station  in  the  world,  the  new  Lafayette  station  near 
Piordeaux,  France. 


.Roiuatt)  Concro.1  ^oy  lladio 


Wrstiimli' 


A.  L.  WILSON 

Radio  Kiifiiiioir, 
M'  I'.lcctric  &  .Mig.  CDiiiijaiiy 


dis 


WHI'lN  in  1S84,  Hertz  made  his  nK^mentous 
covery  that  a  Leyden  Jar  discharged  across  a 
small  gap,  caused  a  corresponding  discharge 
across  a  gap  made  in  a  small  loop  of  wire  having  no 
electrical  connections,  it  was  looked  upon  as  a  scientific 
novelty.  The  possibility  of  applying  this  knowledge  to 
any  commercial  use,  apparently,  at  the  time,  did  not 
occur  to  anyone.  It  would  have  sounded  like  a  story  by 
Jules  Verne  if  f)ne  could  have  recounted  at  that  time  the 
far  reaching  effects  of  this  discovery.  Few  people  of 
the  time  would  have  credited  the  phenomena  with 
revolutionizing  communication — indefed  it  was  hardly 
considered  possible  that  any  form  of  wireless  communi- 
cation other  than  visual  signaling  would  ever  be  accom- 
plished. 

The  advent  of  the  electrical  telegra[)h  did  little  to 
convince  the  general  public  or  even  the  scientific  man 
of  the  age  that  communication  by  means  of  electricity 
would  become  an  every  day  necessity.  When  Marconi 
devised  his  first  wireless  telegraph,  people,  ever 
sceptical,  looked  upon  it  as  the  wild  dream  of  a  hair- 
brained  inventor,  although  they  had  at  this  time  adopted 
the  telegraph  and  telephone.  It  was  only  after  con- 
siderable difficulty  and  after  having  been  turned  down 
by  his  own  government,  that  he  persuaded  the  British 
Post  Office  Department  to  finance  the  building  of  his 
first  experimental  station.  The  Public  looked  on  ask- 
ance, thinking  it  was  .so  much  money  wasted.  What 
would  have  happened  and  what  would  people  have 
thought  if  someone  had  suggested  a  machine,  flying 
through  the'  air,  absolutely  under  the  control  of  a  wire- 
less operator  on  the  ground?     Communication  without 


wires;  an  interesting  experiment  but  of  what  use  could 
it  be  to  the  business  man  of  the  day? 

And  so  at  the  present  time,  one  does  not  realize  the 
tremendous  possibilities,  the  benefit  which  may  accrue 
to  the  world  of  today — a  world  ever  on  the  watch  for 
efficiency,  speed  and  reliability,  from  the  use  of  radio 
phenomena,  in  other  fields  than  communication.  The 
possibilities  of  radio  control  have  been  occupying  the 
minds  of  inventors  since  the  early  days  of  the  art,  but 
there  are  so  many  variable  factors  which  enter  into  the 
problem  that,  until  recen.t  years,  very  little  progress  was 
made.  The  world  war  probably  had  more  to  do  in 
bringing  radio  into  its  present  stage  of  development 
than  would  have  been  accomplished  during  many  years 
of  scientific  investigation. 

To  the  average  individual,  radio  means  "wireless 
telegraphy",  or  might  also  include  "wireless  telephony" 
and  they  would  indeed  be  sceptical  of  any  other  uses  to 
which  it  could  be  adapted.  Communication,  that  is,  of 
the  straight  message  type,  is  but  a  small  part  of  the 
radio  field. 

It  has  long  been  the  dream  of  radio  men  the  world 
over  to  devise  an  efficient  and  reliable  means  of  attract- 
ing the  attention  of  operators.  Since  the  days  of  the 
filings  coherer,  it  has  always  been  necessary  for  the 
operator  to  wear  a  pair  of  headphones  and  continually 
search  over  a  definite  wave  length  range  for  incoming 
signals.  Acoustic  working  presents  marked  advantages 
and  enables  faultless  traffic  to  be  maintained  between 
two  stations,  but  the  disappearance  of  the  coherer  meant 
that  there  was  no  longer  a  simple  accessory  apparatus 
which    allowed    signals   to   be   changed   directly   into  a 


April,  1 92 1 


THE   ELECTRIC  JOURNAL 


147 


strong  mechanical   movement,  such  as  is  necessary  to 
ring  a  bell  and  thus  call  up  a  station. 

One  may  think  of  the  high  power  stations  scattered 
throughout  the  world  and  conclude  that  the  problem  of 
getting  a  considerable  amount  of  energy  to  the  receiving 
station  is  one  of  comparative  ease.  Table  I  gives  a 
comparison  between  transmitted  and  received  energies 
in  various  types  of  electrical  energy  transmitting  sys- 
tems as  given  in  authoritative  text  books. 

Table   I  —  Power  Received  by  Radio   iiiiiiiiinient 


Walls 
Transmitlerl 

Walts 
Received 

Ralio 

lO" 

1 

10  -■ 
10' 

10" 
10  ■' 
10" 
10" 

1 

10  ■ 

10* 

10  I-'          1 

Cable  Telegraph  

Wire  Telephone 

Radio 

From  this  it  would  appear  that,  at  the  maximum 
range  of  the  transmitter,  the  received  power  is  measured 
in  hundred-millionths  of  a  watt.  This  power  is  ample 
to  operate  a  modern  radio  head  receiver,  but  even  the 
most  sensitive  relay  requires  about  one-thousandth  of  a 
watt  to  operate  reliably. 

In  order  to  meet  the  demand  for  a  calling  device 
in  the  early  days  of  the  crystal  detector,  the  Telefunken 
Company  developed  an  instrument  which  would  call  up 
a  station  when  the  energj-  received  was  very  small. 
This  instrument  consisted  essentially  of  a  very  sensi- 
tive  high-resistance  galvanometer   which    could   be  de- 


FIi;.     I Sc  HKMATU      DIACKAM     1)1-     I  AI.LI.\(.     llKVIi  I- 

fleeted  by  the  current  from  the  detector.  A  suitable 
contact  for  working  a  relay  cannot,  of  course,  be  made 
by  the  deflection  of  such  a  galvanometer  needle,  but  the 
instrument  was  so  arranged  that  when  the  needle  de- 
flected beyond  a  certain  angle,  it  came  into  contact  with 
a  toothed  wheel  kept  in  slow  rotation  by  clockwork. 
The  needle  then  became  engaged  with  the  toothed  wheel 
which  carried  the  end  of  the  pointer  down  onto  a  con- 
tact stud,  and  thus  forced  it  into  sufficiently  good  con- 
tact to  complete  a  local  circuit.  This  circuit  operated 
a  drop  indicator, 'which  in  turn  closed  a  circuit  through 
an  alarm  bell  which  continued  to  ring  imtil  the  opera- 
tor released  the  needle. 

The  arrangement  is  shown  diagrammalically  in 
Fig.  I,  in  which  .V  is  the  needle,  and  W  is  the  toothed 
wheel  seen  in  plan.  The  local  battery  is  at  B,  and  when 
contact  is  made  the  relay  R  operates  and  the  bell  rings. 
The  terminals  /  and  //  are  connected  to  the  receiver 
apparatus  in  parallel  to  the  high  resistance  phones,  and 
the  direction  of  the  received  current  is  so  arranged  that 
the  pointer  of  the  instrument  moves  to  the  right,  that  is 


towards  the  wheel.  As  soon  as  the  sending  instrument 
transmits  a  dash  lasting  about  ten  seconds  the  needle 
moves  sufficiently  to  engage  with  the  wheel,  and  ft  then 
rigidly  held,  so  that  the  bell  begins  to  ring. 

The  operation  of  the  apparatus  is  very  simple. 
When  the  terminals  /  and  //,  have  been  connected  to  the 
receiver  and  the  terminals  ///  and  IV  with  the  battery, 
the  needle  of  the  galvanometer  has  only  to  be  undamped 
for  the  instrument  to  be  ready.  The  distance  of  the 
needle  from  the  toothed  wheel  can  be  regulated  and 
thus  any  desired  degree  of  sensitiveness  can  be  obtained. 
For  ordinary  working  a  distance  of  about  one  mm.  is 
used.  When  the  call  has  taken  place  and  the  bell  ring.s, 
the  clamped  needle  can  be  relea.sed  and  the  apparatus 
is  then  ready  for  another  call. 

This  same  apparatus  could  be  developed  to  operate 
any  form  of  control  systems.  With  radio  control  sys- 
tems, however,  there  are  serious  difficulties  to  be  over- 
come before  they  can  be  successfully  applied  to  com- 
mercial use.  Absolute  reliability  is  essential  and  inter- 
ference must  be  prevented.  There  are  three  main 
causes  of  interference,  first,  static  ;  second,  accidental  in- 
terference from  other  stations;  and  thirdly,  willful  in- 
terference. Of  the  three,  the  latter  is  by  far  the  worst, 
although  caused  chiefly  by  a  spirit  of  mischief.  There 
are  a  great  many  schemes  which  will  overcome  one  or 
more  of  these  objections,  but  relatively  few  which  can 
claim  absolute  immunity  from  interference  and  at  the 
same  time  be  rugged  and  reliable.  Codal  selectors  in 
themselves  are  not  enough,  neither  can  time  element  re- 
lays be  used  simply  to  prevent  interference. 

A  systeni  devised  by  the  writer  in  1916  can  be  ap- 
plied to  any  form  of  control  system  and  is  practically 
immune  from  interference  of  all  sorts.  It  consists  es- 
sentially of  a  highly  selective  radio  receiving  set  work- 
ing in  conjunction  with  a  special  transmitter.  It  is 
apparent  that  if  the  selector  mechanism  is  entirely  a 
part  of  the  receiver,  any  transmitter  can  be  ada|)ted  to 
operate  it  from  a  distance. 

The  system  works  as  follows,  it  being  understood 
that  the  whole  operation  is  automatic.  Supposing  the 
control  system  has  been  applied  to  operate  a  sectionaliz- 
ing  switch  on  a  power  transmission  line,  or  any  other 
equipment  which  can  be  actuated  by  power  from  a 
local  circuit  established  by  the  radio  relay,  the  operator 
finding  it  necessary  to  open  the  sectionalizing  switch, 
simply  pushes  a  push-button  switch  in  the  power  house. 
This  starts  the  transmitting  apparatus  which  sends  out 
certain  prearranged  signals.  These  signals  operate  the 
receiving  mechanism  which,  through  suitable  relays, 
opens  the  sectionalizing  switch.  The  interference  and 
other  difficulties  are  overcome  in  the  following 
manner : — 

The  transmitter  is  so  arranged  that  it  sends  out  a 
certain  sequence  of  signals  with  a  definite  time  interval 
between  them,  then  automatically  changing  its  wave 
length,  it  again  sends  out  another  sequence  of  signals, 
and  can  again  change  its  wave  length,  if  desired,  for  a 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


ihird  or  fourth  sequence  of  signals.  These  signals  be- 
ing of  a  certain  length  of  character  and  a  definite  time 
interval  between  them,  the  cycle  of  operations  is  com- 
pleted in  a  definite  time.  At  the  conclusion  of  the  cycle, 
the  transmitting  apparatus  comes  to  rest  and  is  ready 
for  another  operation.  At  the  receiving  end,  the  first 
impulse,  in  addition  to  rotating  a  selective  switching  ar- 
rangement, starts  an  escapement  movement,  which  is 
previously  set  so  that,  unless  the  impulses  are  received 
at  the  correct  moment,  or  the  cycle  of  operations  com- 
pleted within  the  predetermined  time  interval,  the  re- 
ceiver is  automatically  reset,  at  what  might  be  called  the 
zero  point.  The  transmitter  is  shown  diagrammatically 
in  Fig.  2,  in  which  5  is  a  message  wheel,  having  the 
signals  and  proper  spaces  cut  in  the  periphery.  This 
wheel  is  automatically  rotated  one  complete  revolution, 
(or  more  as  desired  according  to  the  setting  of  the  re- 
ceiver time  element)  when  the  push  button  switch  is 
operated,  making  or  breaking  contact  with  brush  C„. 
This  brush,  closing  the  circuit  through  R^,  operates  the 
radio  transmitter  proper  and  causes  impulses  to  be  sent 
out.  The  radio  apparatths  is  shown  for  clearness  only 
.!-;    a    ^prirk    transmitter,    jinwer    being    supplied    to    ter- 


minals /  and  //,  7'  being  the  transformer,  F  the  spark 
gap,  D  the  condenser,  0  the  oscillation  transformer,  A 
the  antenna  and  G,  ground. 

Rotating  with  what  may  be  called  the  "message" 
wheel  is  the  wave  change  operating  wheel  U\  which 
makes  contact  with  brush  C,,  closing  the  circuit  through 
relay  R„.  This  relay,  by  a  pawl-ratchet  motion  rotates 
the  two  wave  changing  switches  Fj  and  P  .■ 

The  system  lends  itself  to  considerable  changes 
which  may  be  quickly  made,  allowing  for  the  control 
of  different  switches  or  other  apparatus  without  inter- 
fering with  the  other  parts  of  the  system.  For  instance, 
different  message  wheels  could  be  used  for  each  switch 
or  the  wave  length  clips  could  be  moved,  thereby  using 
different  combinations  of  wave  lengths,  or  a  different 
number  of  wave  lengths  could  be  used,  or  a  combination 
of  all  these  changes. 

The  receiver  is  shown  diagrammatically  in  Fig.  3, 
in  which  A  is  the  antenna  and  G  ground,  in  series  with 
which  is  the  condenser  V  and  inductance  L,.  The  cir- 
cuit shown  is  a  simple  regenerative  detector  arid^~two 


step  amplifier,  in  which  D  is  the  detector  bulb,  .-ij  and 
A.,  the  amplifier  bulbs  and  T^  and  7",  the  intervalve 
transformers.  Instead  of  a  headphone  being  connected 
in  the  plate  circuit  of  the  last  amplifier  bulb,  as  is  the 
usual  practice,  a  sensitive  relay  is  used,  the  operating 
coil  of  this  relay  being  connected  to  "message"  wheel 
M  by  means  of  brush  C,.  In  the  "zero"  or  off  position 
of  this  wheel,  brush  C,  is  in  contact  with  the  first  im- 
l)ulse  contact  on  the  wheel,  thus  permitting  the  first  im- 
pulse received  to  operate  the  relay  R^.  This  relay  is  in 
series  with  the  time  element  control  and  releases  the 
escape  movement,  which  also  rotates  the  message  wheel 
M.  It  will  be  seen  that  unless  the  signal  is  received  at 
the  proper  instant,  the  message  wheel  will  be  in  a  neu- 
tral position  with  respect  to  the  brush  C,  and  no  im- 
I'ulse  will  be  received.  In  the  time  element  7"  is  a  du- 
|)licate  of  the  message  wheel,  acting  on  the  escapement 
in  such  a  way  that,  unless  a  signal  is  received  at  the 
correct  interval,  the  whole  mechanism  returns  to  zero 
and  will  require  a  coi^iplete  cycle  of  operations  to  be 
effective. 


R.^DIO   FErEUER    FOR    REMOTE    CONTROl. 


Rotating  with  the  message  wheel  is  the  wave 
changing  wheel  Q  making  contact  with  brush  C,,  which 
completes  the  circuit  through  the  operating  coil  of  re- 
lay 7?,.  This  relay  operates  the  wave  changer  switch, 
shown  simply  as  increasing  the  turns  of  the  inductance 
in  the  antenna  circuit.  These  extra  turns  are  shown 
as  L.,  and  L,.  The  relay  R„  closes  the  final  circuit  of 
the  controlled  api>aratus  which  is  connected  to  terminals 
III  and  IW 

This  system  is  applicable  to  any  apparatus  which  is 
desired  to  control  from  a  distance  by  means  of  radio, 
and  the  switching  operations  effected  by  the  local  cir- 
cuit can  be  made  as  complex  as  required,  without 
sensibly  affecting  the  comparative  simplicity  of  the  ap- 
paratus. 

The  radio  transmission  of  power  would  revolution- 
ize traction  and  industry.  The  metering  of  such  power 
might  tax  the  ingenuity  of  meter  engineers,  but  un- 
doubtedly this  could  be  overcome.  The  future  appli- 
cations of  the  art  are  as  impossible  to  conceive  as  were 
the  present  developments  of  Hertzian  waves. 


Coii\mi((iicai;iOji  Jun^^inaoriiig  a'c   Yale 

H.  M.   TURNER 

Assistant   Professor  of  Electrical  Engineering. 
Vale  University 

MAXW  ELL'S  mathematical  deductions  conimuni-  a\ailable   in  undergraduate   courses  and   in   instruction 

cated  to  the  Royal  Society  in   1864,  predicted  of  the  students  who  ha\'c  enlisted  in  the  R.  O.  T.  C.  Sig- 

the    propagation    of    electromagnetic    waves    at  nal   Corps   group.     Instruction   in   the   latter   group   is 

finite  velocity.     However,  this  beautiful  theory  lacked  given  by  a  detailed  officer  of  the  Signal  Corps  and  the 

experimental     confirmation.       In     1888     Hertz,     after  apjiaratus  is  regularly  cared  for  by  Government  custo- 

several  years  of  intentionally  directed  effort  towards  an  dians  detailed  for  the  purpose. 

experimental  verification  of  Maxwell's  electromagnetic  In  addition  to  the  equipment  supi)lied  by  the 
theory,  established  the  proof  and  laid  the  foundation  of  Government,  there  is  available  the  equipment  of  the 
radio  engineering.  It  is  said  "There  is  not  in  the  entire  electrical  engineering  laboratory  and  of  the  physics 
annals  of  scientific  research  a  more  completely  logical  laboratory  to  which  recent  additions  have  been  made, 
and  philosophical  method  recorded  than  that  which  has  Furthermore,  the  comnnmication  companies  have 
been  rigidly  adhered  to  by  Hertz  in  his  researches  on  loaned  special  demonstration  ap])aratus.  All  these  fac- 
the  propagation  of  electric  waves  through  space."  As  tors  contribute  to  a  complete  and  up-to-date  equipment 
a  result  of  the  imagination  of  these  men  and  their  ability  for  instruction  in  commtmication  engineering. 
to  visualize,  it  is  now  possible  to  communicate  between  The  course  of  instruction,  based  upon  broad  fun- 
any  two  places  regardless  of  whether  they  are  on  land,  damental  principles  underlying  the  generation,  propa- 
ship,  airplane  or  submarine.  gation  and  utilization  of  electromagnetic  waves,  is  ad- 

If  our  universities  are  to  produce  radio  engineers  ministered  in  such  a  \va\-  as  to  develop  the  student's 
of  vision,  capable  of  the  highest  scientific  attainments,  analytical  power.  In  order  to  deal  ([uantitatively  with 
who  will  in  time  extend  the  boundaries  of  our  present  this  subject,  it  is  necessary  to  use  mathematics,  which  is 
knowledge,  the  imagination  must  be  developed.  Lest  nothing  but  a  rational,  .systematic  and  scientific  way  of 
the  students  become  discouraged  by  the  wonderful  pro-  expressing  physical  truths  or  relations  between  physical 
gress  that  has  already  been  made,  attention  is  called  to  quantities  where  measurements  of  relative  magnitude 
the  fact  that  each  new  development  opens  up  innumer-  are  involved.  The  mathematical  analysis  of  comniuni- 
able  opportunities  for  improvements,  inventions  and  dis-  cation  engineering  problems  is  a  |)ovverful  aid  for 
emeries  and  these  in  turn  reveal  other  undeveloped  directing  the  mind  towards  the  correct  solution,  for  de- 
fields.  The  student  little  appreciates  the  many  fascinat-  veloping  the  deductive  and  reasoning  faculties,  and  for 
ing  problems  that  are  yet  to  be  solved.  He  senses  but  testing  the  accuracy  of  one's  knowledge.  A  reference 
^■aguely  the  opportunities  that  are  his.  to  the  literature  of  the  subject  will  convince  the  student 

During  the  war  the  Signal  Corps  of  the  United  and  engineer  of   the   importance  of   this  phase   of  his 

States  Army   re(|uired   competent  radio  engineers  and  training.     While  it  is  necessary  for  the  student  to  ac- 

radio  officers,  and  a   large  number  of   men  who  were  quire  facility  in  handling  mathematical  expressions,  it 

lamiliar  with  the  operation  of  telephone  and  radio  ap-  is  even  more  important  that  he  be  able  to  interpret  these 

paratus.     Many  schools  were  established   for  training  mathematical    expressions    in    terms    of   the   physical 

radio  officers  and  operators,  one  of  which  was  moved  i<henomena  and  to  express  the  physical  phenomenon  in 

to    Yale    in    the    summer    before    the    armistice.     The  equational  Torm   for  the  purpo.se  of  computation.     In 

original  plan  was  to  send  to  the  school  100  picked  men  other  words,  the  purely  symbolic  or  sign  language  of 

each    month    for   a    three   months'   course,   making   the  the  mathematician  is  made  a  vital,  living  language  of 

normal  attendance  300.     .\t  the  time  of  the  signing  of  the      engineer,     expressing     definite,      understandable 

the  armistice  there  were  nearly  500  officer  candidates  i/hysical  relations  with  which  he  is  concerned, 

in  training.     The  Government  sent  a  number  of  com-  The  theoretical  and  experimental  study  of  circuits 

petent  officers  and  a  large  supply  of  both   indoor  and  rmd  ecjuipment  are  so  intimately  related  that  the  student 

field  apparatus  for  instruction.     After  the  armistice  the  acquires  familiarity  with  the  phenomenon  and  confid- 

Signal  Corps  arranged  to  continue  a  group  of  officers  ence  in  his  ability  to  predict  with  precision  the  results 

at  Yale  for  advanced  training  in  communication  engi-  to  be  obtained,  when  the  conditions  of  a  problem  are 

neering  with  particular  reference  to   radio.     Much  of  specified.  Much  depends  upon  a  good  laboratoiy  course 

the  equipment  supplied   for  the  earlier  instruction  re-  where   practice  and   the   rigid   requirements  of  t"heory 

mains  and  additional  apparatus  has  been  supplied  by  the  are  brought  into  harmony.     One  experimental   means 

Government.     This  serves  for  the  advanced  instruction  of  giving  the  student  a  definite  understanding  of  the 

of  officers  and  others  in  the  graduate  courses.     It  is  also  action  in   radio   circuits  is  a   svnchronous  switch  used 


THE  ELECTRIC  JOURNAL 


\  ol.  >!V1II,  No.  4 


with  the  oscillograph  nv  connection  with  the  experi- 
mental study  of  transient  electrical  phenomena,  so  that 
a  change  in  any  of  the  circuit  conditions  may  be  in- 
stantly observed  on  the  screen  of  the  oscillograph.  This 
switch  makes  it  possible  for  the  student  to  observe 
upon  lite  screen  the  effect  of  a  variation  in  R,  L  or  C 
upon  the  frequency  and  decrement  of  simple  oscillatory 
circuits ;  of  a  variation  of  coupling  between  primary  and 
secondary  of  coupled  oscillatory  circuits;  of  detuning; 
of  introducing  resistance  in  either  primarj-  or  second- 
ary; of  impulse  excitation;  of  quenched  gap  action;  of 
connecting  any  type  of  circuit  across  an  alternating 
electromotive  force  at  any  desired  point  of  the  wave, 
which  may  be  varied  uniformly  from  o  to  90  degrees 
wliile  making  an  observation;  of  starting  currents  in 


the  transformer  where  the  operator  controls  the  point 
of  closing  the  circuit  and  also  the  amount  of  residual 
magnetism  in  the  transformer;  etc.  This  gives  the  stu- 
dent an  insight  into  transient  electrical  effects  and  the 
operation  of  radio  circuits  of  permanent  value.  Special 
emphasis  is  placed  upon  the  preliminary  study  of  the 
phenomena  on  the  screen  before  taking  oscillograms  for 
the  purpose  of  computation  and  record.  The  theoiy  is 
experimentally  verified  the  same  as  that  of  periodical 
alternating  current.  However,  greater  precision  is 
possible  and  each  exi>eriment  is  subjected  to  a  rigorous 
mathematical  analysis.  The  students  study  the  differ- 
ent types  of  radio  equipment  in  the  laboratory  and  also 
in  the  field. 


WosiiBgiiOK^o  Teclmkal  W5;>;ht  CSdiooi 


VV.  W.  REDDIE 

Director, 
Electrical  Departmeut,  W. 


THE  W  estinghouse  lechmcal  Night  School, 
fostered  by  the  Westinghouse  Electric  &  Mfg. 
Company,  offers  young  men  who  must  earn  their 
living  during  the  day  time,  an  opportunity  to  study  the 
fundamentals  of  engineering  while  they  see  the  prin- 
ciples and  theory  studied,  applied  in  their  daily  work. 
It  oft'ers  young  women  an  opportunity  to  fit  themselves 
for  responsible  positions  in  the  commercial  world  and 
in  the  community.  The  training  in  the  engineering 
school  is  not  specialized,  but  is  general  and  provides  an 
excellent  foundation  in  shop  practice,  mathematics, 
mechanics  and  the  fundamental  principles  of  steam  and 
electrical  engineering.  The  student  obtains  tliat  thor 
f  ugh  knowledge  of  fundamental  principles  which,  when 
applied  in  practice,  result  in  skill  in  any  chosen  line. 
The  Night  School  aims  to  develop  character  and  make 
men  more  useful  to  their  fellowmen,  both  socially  and 
technically. 

The  School  benefits  first,  the  student  himself,  by 
giving  him  training  which  enlarges  his  vision,  and  en- 
ables him  to  gain  more  of  success,  by  whatever  stand- 
ards that  success  may  be  measured;  second,  it  benefits 
industry,  in  that  the  skill  of  the  student  is  increased  and 
his  ability  developed  b}^  technical  training;  third,  it 
benefits  the  community,  in  that  a  more  useful  citizen  ■ 
made  by  the  training  given.  Correspondingly,  three 
sources  of  revenue  maintain  the  school.  First,  the  stu- 
dent pays  a  tuition;  second,  industry  contributes  to  the 
.-'upport  of  the  school  through  appropriation;  and  third, 
the  communit}'  contributes  through  public  school  co-op- 
eration. The  classes  are  conducted  in  the  public  school 
buildings  of  the  neighboring  communities.  Many  stu- 
dents enroll  in  the  Night  .School  courses  who,  through 
force  of  circumstance,  have  left  the  common  schools 
after  passing  the  eighth  grade,  or  even  before.  These 
students,  working  in  the  shops  and  factories  during  the 


day-time,  carry  on  their  studies  in  the  evenings  and  are 
able,  in  the  course  of  time,  to  enjoy  the  opportunities, 
rewards,  and  success  open  to  the  trained  man. 

The  curriculum  includes  Foreign,  Preparatory,  En- 
gineering, Post-graduate,  Extension  and  W  omen's  De- 
partments. 

The  foreign-born  resident,  unable  to  sjieak,  read  or 
write  English  can  enter  the  Foreign  Department  and  by 
diligently  and  conscientiously  following  his  studies  for 
eight  years,  progressively  pass  through  the  Foreign, 
Preparatory  and  Engineering  Departments  of  the  Night 
.School  and  graduate  with  a  working  knowledge  of  the 
fundamental  principles  of  engineering.  This  state- 
ment, of  course,  pre-supposes  that  the  student  has  had 
some  public  school  education  in  his  native  land.  A 
number  of  the  alumni  of  the  school  have  passed  through 
these  departments  and  their  subsequent  success  has  been 
a  credit  to  the  school. 

Generally,  students  who  have  completed  the  eighth 
grade  of  public  school  work,  are  admitted  to  the  Engi- 
rceering  Department,  although  all  applicants  are  given 
;.  thorough  oral  examination  to  check  their  knowledge 
of  the  mathematics  that  should  be  obtained  in  the  public 
schools.  Students  w'ho  have  not  completed  the  eighth 
grade  or  who  do  not  qualify  by  oral  examination,  are 
required  to  take  preparatory'  work,  which  may  extend 
over  a  maximum  period  of  two  years. 

Work  in  the  Engineering  Department  covers  a 
period  of  four  years  of  thirty-six  weeks  a  year,  three 
nights  of  three  hours  each  per  week.  The  total  num- 
ber of  school  hours,  recitation  and  laboratory  work  thus 
;anounts  to  1,296  hours.  A  student  will  average  about 
T.5  hours  outside  study  for  each  hour  spent  in  school, 
so  that  the  total  number  of  hours  spent  in  self-develop- 
ment during  this  four-year  period  will  be  from  3000  to 

■'•^rvi  linnr.;   inr  tlip  fi\-er,Tjrp  ctndent         r;ihlp  T    ~lifiws  the 


Ai>ril,   ii(-M 


THE   ELECTRIC  JOLRNAL 


;  eiceutage  of  time  devoted  to  various  branches  of  the  in  cities  where  service  deiiarinienis  are  located.      Tlie-c 

Engineering  Course.     It  is  interesting  to  see  tliat  27.8  branches  are  open  to  all  emijloyees  who  wish  to  enroli. 

percent  of  the  total  time  is  devoted  to  mathematical  sub-  .\n  extension  branch  has  been  started  at  Homewoo-i. 

iects  while  2t).8  i)ercent  of   the  time   is  given   to  the  (Pittsburgh),   and    New   York,   Buffalo,   Atlanta,   S.in 

theory   and   practice   of   direct   and  alternating-current  I'ranciscu.  and  Seattle  extension  branche- will  i„.  .....; 

electricity.  b.shed  in  the  near  future. 

The  school   is  equipped    with   electrical,   chemical,  The  Women's  Department  of  the  M^iiDm  (Piur-, 

and  physics  laboratories,  and  the  courses  are  arranged  preparatory  course  of  one  }ear,  a  two  year  commerci.ii 


to  correlate  and  co-ordinate  the  class-room  work  with 
the  laboratory  work.  Increasing  enrollment  has  neces- 
sitated ma.ximum  utilization  of  available  space.  The 
Icctrical  laboratory,  as  an  example  of  this,  is  parti- 
liuiied  into  four  compartments,  two  for  alternating-cur- 
rent and  two  for  direct-current  work.  A  common 
power  relay  serves  the  four  comjiartments  and  in  order 
to  provide  maximum  free  floor  space  all  switch  gear, 
meter  boards,  and  rheostats  are  mounted  on  the  ])arti- 


course,  a  one  }ear  course  in  calculating  machine  oper,-i 
tion,  a  two  year  course  in  >ewing,  and  a  special  one  yea: 
post-graduate  courses  in  I'.iiglish  and  dictation.  Tli. 
commercial  course,  the  calculating  machine  operntioi; 
and  the  dictation  courses  are  planned  so  that  sf.ideni- 
may  .ipply  the  work  studied  in  school  to  then  practical 
work  in  business  and  engineering  offices. 

All  classes  are  conducted  by  men  and  women  wh.i 
are  acti\ely  engaged  in  practical  work  and  who  are 
specialists  in  their  particu- 
lar lines.  They  have,  for 
the  most  part,  had  a  tech- 
nical education  followed 
by  wide  experience  anil 
broad  training,  and  are 
thus  well  able  to  judge  the 
kind  of  men  needed  in  llu 
industrial  world,  and  to  de- 
velop the  students  accord- 
ingly. 

The  methods  of  in- 
-iruction  would  hardly  be 
expected  to  check  with 
methods  of  instruction  in 
general  use  in  the  day  col- 
leges and  schools.  The 
aim  is  to  teach  the  student^ 
the  principles,  which  are 
the  tools  with  which  they 
must  work  in  solving  prob- 
lems which  they  will  be 
called  upon  to  solve.  The 
;i|iplications  of  these  prin- 
ciples are  pointed  out  and 
practice  is   given    in    using 

tions.  as  shown  in  Fig.  I.  ihem.    Ihe  thought,  always  before  the  instructor,  is  that 

Another     example     of     eliiciencv     ]-iracticed,     as      he  must  assist  the  student  to  translate  the  theory  and 

preached  to  students,  is  found  in  the  utilization  of  class     principles  .studied,  into  ihe  efficient  utilization  of  men 


-i;i.KCTKIC.\r,   L.M!OR.MORY 

then 


rooms.  Five  minute  physical  drill  led  by  one  of  the 
class,  is  given  between  periods,  in  order  to  provide  the 
necessary  inlermission  and  relax.ition  between  recita- 
tions. 

The  post-graduate  course  was  established  in  19^0. 
and  courses  in  radio  engineering,  industrial  economics, 
electrical  machine  design,  laws  and  contracts  in  engi- 
neering, and  practical  calculus  are  ofifered  to  the  ahnnni 
of  the  school  and  others  who  are  interested  in  these  ad- 
vanced classes. 

An  Extension  Department  is  being  de\el(.|ied  for 
ihe  Ijcnefit  of  emploj^ees  of  the  Westinghouse  t'ompany. 


and   materials  in   the  manufacture  and  application   n{ 
machinery. 

The  work  in  the  drawing  room,  pattern  shop  and 
foundry  is  pro|)erly  correlated  to  give  the  stu- 
dent an  idea  of  the  application  of  theory  to  ])rac- 
tice.  and  hc\\>  him  \isunlize  the  processes  h\  whicli 
machinery  is  manufactured  and  projects  are  CHri-ic<! 
out.  The  student  makes  drawings  in  the  drawing: 
room  for  the  parts  for  which  he  makes  patterns  in  iln 
pattern  shop.  Later  he  makes  castings  and  machine- 
from  these  same  patterns  which  he  has  followed 
through  from  their  conception. 


THE   ELECTRIC  JOURX.IL 


\'ol.  XVIII,  No.  4 


The  courses  and  class-room  work  are  planned  to 
stimulate  the  student  to  independent  thought.  The 
doctrine  of  the  instructor  is  that  unless  a  student  can 
he  taught  to  analyze,  assemble  the  facts  and  combine 
them  to  form  logical  conclusions,  the  instruction  given 
is  of  more  or  less  temporarj*  character. 

The  laboratory  courses  .synchronize  as  far  as 
possible   with    class-room   work   and   all  courses  are  co- 


131"' 
■1  .'IJO 
1100 

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\ 

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-900 

-son 

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s 

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/ 

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2 

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, 

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3     0 

^    (I's    ois    07    o'8   0^    I'c    n    12    13    n    15    16    \^    is    is    i" 

5     116     07     08     09     10       11      \2     13     H      15      16     17     18      1?     20     21 
1        1       1        1        r       1        1    Sc'hooJv^'r       1        1       1        1      1        1 

FIG.    2 — WESTINCHOUSE    TECHN1C.\L    NIGHT    SCHOOL    ENROLLMENT 
BY  YEARS 

ordinaled  in  such  a  manner  that  the  relation  and  ap- 
plication of  algebra,  geometry,  and  trigonometry,   for 


3— Knows  the  application  of  every  machine  lie  has 
studied  and  the  why  of  it. 

4— Knows  where  to  look  for  knowledge  that  he  does 
not  have. 

5— Has  a  working  knowledge  of  the  generation,  dis- 
tribution, control  and  utilization  of  electrical  energy. 

6 — Is  capable  of  attacking  problems  within  the  scope  of 
his  development. 

7 — Grasps  and  can  apply  the  principle  that  economy 
dictates  for  most  designs  and  applications  of  machinery'; 
that  economy  in  choice  and  use  of  materials,  cfiiciency  in 
the  labor  of  assembling  and  working  the  materials,  effi- 
ciency in  the  generating  and  application  of  power,  all  com- 
bine to  turn  out  more  work  at  less  cost. 

The  nature  of  the  work  carried  on  at  the  Night 
.School  has  involved  the  preparation  of  several  texts 
which  particularly  fit  the  methods  of  instruction  used. 
Among  these  texts  are  included  an  Industrial  Speller, 
Shop  Problems,  Physics  Notes,  Mechanics  Notes, 
Notes  on  ^letallurg)',  and  a  set  of  Engineering  Prob- 
lems which  involve  the  applicatioii  of  electricity, 
])hysics,  chemistry,  steam,  and  mathematics  to  practical 
]iroblems  of  design,  manufacture,  distribution  and  op- 
eration. 

A  Students  Association,  of  which  all  students  are 
members,  regulates  all  outside  school  activities  and  has 
developed  an  excellent  school  spirit.  The  Association 
elects  its  own  officers  who,  with  the  class  presidents, 
constitute  the  governing  body.  This  governing  bodv 
manages  the  student  affairs  and  exercises  control  over 
the  students  through  the  class  presidents.  The  Stu- 
dents   Association    maintains    football    and    basketball 


TABLE  I-ENGINEliKI.NG  Dlil'ARTM 
4  Ycars-36  Weeks  Per  Year— 9  Hou 


ii.\r-iJisTHiuurio.N  OK  nouns 

rs  Per  Week— Total  Hours  1296, 


Year 

Term 

Mechanical 
Drawing 

Shop  Work 

Malhcmatus 

Physics 

Business 
English 

IJlcctricity 

Chemistry 

Steam 

Metallurgy 

iM-esli. 

I 

36 

I'oundrv 

36 

Pattern  Shop 

36 

Shop 

Problems 

54 

II 

108 

Algebra   34 

Sopli. 

I 

Machine  Shop 

108 

Algebra   54 

II 

Geonu-lrv  and 
Trig.   54 

108 

junior 

I 

Mechanics 

36 

54 

36 

D.  C.  36 

II 

Mechanics 

36 

D.C.  andA.C. 
90 

36 

Senior 

I 

Engineering 
Problems  36 

D.C.  andA.C. 
90 

36 

II 

Engineering 
Problems  36 

A.  C.  54 

36 

36 

Total  H 
Bra 

ours  per 
nch 

144 

180 

360 

162 

36 

270 

36 

72 

36 

Percent,  of 
Total 

11. 1 

13.9 

27.S 

12.3 

2.7S 

20.8 

2.78 

5.56 

2.78 

example,  to  their  practical  use  and  application  in  engi-  teams  and  conducts  the  Annual  Banquet  which  is  at- 

neering  problems  is  kept  before  the  students.    The  ideal  tended  by  500  to  600  students.     This  gives  the  student 

of  a  W.  T.  N.  S.   instructor  is  to  graduate  a   student  leaders  an  opportunity  to  gain  experience  in  managing 

who: — ■  business  affairs.     Much   of  the   success   of   the   Night 

I— Knows  the  fundamentals  of  theory  he  has  studied.  School  has  been  due  to  the  ideals  of  the  founders  and 

2-Knows    where    these    fundaiiientsf^t    in    with    the  ji^g  jgaders  who  have  been  a.s.sociated  with  the  school. 

design  and  manufacture  of  electrical  machinery. 


EDWIN   H.   ARMSTRONG 

EDWIN  II.  ARMSTRONG'S  contribution  to  the  radio  art,  particularly  the  vacuum  tube  radio  art,  is 
epoch  making.  No  one  who  has  empyoyed  his  feedback  or  regenerative  circuit  can  fail  to  appreciate  its 
eminent  value  and  inexhaustible  possibilities.  Armstrong  made  his  invention  when  he  was  about  21  years 
of  age  and  before  he  graduated  in  the  Department  of  Electrical  Engineering  at  Columbia  University  in  1913. 
Although  the  original  discovery  was  more  or  less  accidental,  Armstrong  soon  appreciated  the  real  meaning 
of  it  and  applied  it  to  the  construction  of  the  vacuum  tube  oscillator,  which  is  more  easily  and  accurately 
controllable  than  any  other  oscillator  in  existence.  The  regenerative  receiver  and  the  regenerative  oscilla- 
tor will  always  figure  among  the  classical  inventions  and  will  occupy  a  foremost  position  in  the  research 
laboratory,  as  well  as  in  the  commercial  wireless  service.  It  entitles  Armstrong  to  a  very  high  place  among 
electrical  inventors. 

When  I  was  in  Paris  in  the  Spring  of  1919  I  met  General  Ferrie,  the  Chief  of  the  Signal  Corps  of  the 
Allied  Armies.  Armstrong  was  working  under  him.  The  general  paid  me  several  well  meant  compliments 
which  I  refused  to  accept  on  the  ground  that  I  had  done  so  little  for  his  Signal  Corps.  "Ah,  Monsieur  le 
Professeur"  exclaimed  he,  "but  have  you  not  given  us  Armstrong.'' 

—PROF.  M.  I.  PUFIN. 


THE  question  as  to  how  the  invention  of  the  re- 
generative or  feed  back  circuit  came  about  can 
best  be  answered  by  the  statement  that  it  was  the 
result  of  a  streak  of  luck — and  the  kind  of  luck  that 
comes  once  in  a  lifetime.  For,  all  things  considered, 
the  operation  of  the  regenerative  circuit  involves  too 
many  new  phenomena,  inextricably  woven  together  with 
the  operation  of  the  audion,  a  device  whose  action  was 
clouded  in  the  mystery  of  the  DeForest  gas  ionization 
theory  at  the  time  the  invention  was  made,  for  any  one 
seriously  to  lay  claim  to  a  mental  pre-conception  of  the 
operation  of  the  feedback  method  of  amplification  and 
oscillation. 

The  invention  was  the  result  of  an  idea — the  kind 
of  idea  which  may  be  best  expressed  in  the  form  "what 
would  happen  if"  certain  additions  should  be  made  to 
existing  apparatus.  The  resulting  trial  of  these  addi- 
tions uncovered  a  series  of  new  phenomena  based  on  a 
new  principle.  The  discovery  came  out  of  a  desire  to 
find  out  exactly  how  the  audion  detector  detected — not 
an  easy  thing  to  do  in  the  dark  ages  of  '11  and  '12  when 
the  very  scanty  literature  on  the  subject  explained 
(without  explaining)  that  the  action  was  due  to  ionized 
gas,  and  the  audion  was  known  to  the  art  simply  as  a 
detector  of  high  frequency  oscillations. 

To  find  out  exactly  what  went  on  in  the  tube,  I 
started  an  investigation.  This  was  carried  on  under 
considerable  difficulty,  since  my  main  object  in  life  just 
then  was  supposed  to  be  the  obtaining  of  the  degree  of 
Electrical  Engineer  at  Columbia  University,  and  the 
professors  could  not  be  relied  upon  for  the  necessary 
charity  mark  of  6  unless  a  certain  so-called  reasonable 
amount  of  time  was  devoted  to  their  particular  courses. 

However,  during  this  investigation  it  was  observed 
that  a  condenser  placed  across  the  telephone  receivers 
in  a  simple  audion  receiver  sometimes  gave  an  increase 
in  signal  strength;  not  much  of  an  increase,  but  never- 
theless a  very  definite  increase,  and  with  only  a  small 
value  of  capacity.     Now  I  had  tried  a  condenser  across 


the  phones  many  times  before  (what  amateur  has  not, 
when  graduating  to  the  audion  from  the  crystal  de- 
tector stage,  where  telephone  shunt  condensers 
f)riginated)  but  never  before  had  there  been  any  ob- 
servable change  in  signal  strength.* 

The  small  condenser  indicated  strongly  the  pres- 
ence of  high  frequency  oscillations  in  the  plate  circuit, 
and  I  thought  about  it  a  great  deal  without  being  able 
to  account  for  their  presence  there  in  any  satisfactory 
manner.  During  the  summer  vacation  that  year,  an 
idea  was  suggested  by  the  fundamental  axiom  of  radio, 
"wherever  there  are  high  frequency  oscillations  tune 
the  circuit,"  and  the  idea  was  to  see  what  would 
happen  if  the  plate  circuit  of  an  audion  detector  should 
be  tuned  by  means  of  an  inductance. 

All  the  old  timers  remember  C.C.  later  known  as 
AI.C.C.  and  W.C.C,  the  Marconi  press  station  at  Well- 
fieet,  Mass.  This  station  was  the  one  hundred  percent 
reliable  testing  standby  of  all  experimenters,  and  on 
M.C.C.  the  first  test  was  made.  A  standard  audion  de- 
tector system  was  set  up  and  tuned  in,  and  a  tuning  in- 
ductance introduced  into  the  plate  circuit  of  the  audion. 
Then  various  things  began  to  happen.  As  the  plate  in- 
ductance was  increased,  the  signals  were  boosted  in 
strength  to  an  intensity  unbelievable  for  those  days,  the 
more  inductance  the  louder  the  signal,  until  suddenly 
the  characteristic  tone  of  M.C.C. — the  tone  which  any 
of  the  old  timers,  if  they  heard  it  on  Judgment  Morn, 
would  recognize  instantly — disappeared,  and  in  its  place 
was  a  loud  hissing  tone,  undeniably  the  same  station,  but 
recognizable  only  by  the  characteristic  swing  and  the 


*The  reason  for  the  increase  in  signal  strength  obtained 
when  the  telephone  receivers  in  the  simple  audion  circuit  are 
shunted  by  a  condenser,  remained  unknown  for  a  number  of 
years.  The  explanation  is  an  interesting  one — the  ordinary 
audion  circuit  is  not  a  neutral  device  as  regards  reaction  be- 
tween the  plate  and  grid  circuits.  There  is  a  reaction  which  is 
in  the  opposite  sense  to  the  regenerative  reaction  :  that  is,  the 
plate  circuit  robs  the  grid  circuit  of  energy.  This  is  because  of 
the  capacity  reactance  of  the  telephone  receivers.  When  this  is 
decreased  by  a  paralUl  condenser  the  signal  strength  increases. 


154 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


messages  transmitted.  A  slight  reduction  of  the  plate 
inductance  and  the  old  tone  was  back  again, — and  then 
the  placing  of  the  hand  near  a  tuning  condenser  and  the 
hissing  tone  reappeared.  It  required  no  particular 
mental  effort  to  realize  that  here  was  a  fundamentally 
new  phenomenon,  as  obscure  as  the  principle  of  the 
operation  of  the  audion  itself,  but  which  opened  up  an 
entirely  new  field  of  practical  operation. 

Here  the  element  of  luck  ended  and  it  became 
simply  a  case  of  a  lot  of  hard  work,  digging  out  the 
meaning  of  the  various  phenomena.  A  long  series  of 
experiments  was  carried  out  on  different  wave  lengths 
and  with  various  circuit  modifications,  and  it  became 
possible  on  a  small  amateur  antenna  to  receive  readable 
signals  from  the  navy  shore  stations  on  the  Pacific 
coast,  the  Manoas  and  Porto  Vehlo  stations  in  Brazil 
and  the  Marconi  transatlantic  station  at  Clifden,  Ire- 
land, with  regularity  every  night,  a  performance  which 
a  few  months  before  was  undreamed  of.  But  while 
the  method  of  producing  these  results  was  known,  many 
of  the  phenomena  involved  were  as  obscure  as  ever. 
The  most  striking  of  the  various  phenomena  was,  of 
course,  the  change  of  tone  and  the  investigation  centered 
on  this.  A  number  of  things  contributed  to  the  sus- 
picion that  the  hissing  state  was  due  to  the  production 
of  local  oscillations  by  the  system.  With  this  idea  and 
the  aid  of  some  instruments  borrowed  from  one  of  the 
university  laboratories,  it  was  a  relatively  simple  matter 
to  determine  that  this  was  actually  the  case.  Once  it 
was  apparent  that  the  system  was  capable  of  generat- 
ing oscillations,  the  explanation  of  another  phenomenon 
became  plain.  I  had  observed  on  a  number  of  occasions 
during  the  course  of  listening  to  various  stations,  that  a 
whistling  note  would  frequently  appear  in  the  tele- 
phones, which  could  be  varied  by  adjustment  of  the  re- 
ceiving apparatus.  I  observed  this  particularly  in  the 
course  of  listening  to  a  wireless  telephone  station. 
After  the  discovery  of  the  generating  feature  of  the 
system,  the  .explanation  of  the  change  in  tone  became 
apparent — the  system  was  acting  as  a  heterod}ne  re- 
ceiver.*    A  series  of  tests  confirmed  this  explanation. 

That  is  briefly  the  story  of  how  the  invention  of  the 
feedback  circuit  came  about,  and  how  its  properties  of 
acting  as  a  generator  and  a  self -heterodyne  were  dis- 
covered. Since  that  time  a  vast  amount  of  work  has 
been  carried  out  in  investigating  in  detail  the  precise 
manner  in  which  the  various  phenomena  occur  and  in 
determining   quantitatively   the   amplification   given   by 


*E)iagrams  and  a  description  of  the  operation  of  the  re- 
generative circuit  are  given  in  this  issue,  p.  140. 


the   circuit   in  both  the  non-oscillating  and  oscillating 
slate. 

Without  considering  the  actual  mechanism  of  the 
operation  of  the  system  let  us  consider  the  physical  re- 
sults accomplished  in  practice.  Consider  first  the  re- 
sults in  the  non-oscillating  state.  Measurements  of  the 
signal  energ}'  in  the  telephone  receivers  show  that  an 
amplification  of  from  100  to  1000  results  from  the  re- 
generative action,  the  value  depending  on  the  strength 
of  the  incoming  signals,  the  greater  amplification  being 
obtained  on  the  weaker  signals.  By  reason  of  the 
nature  of  the  amplification,  which  is  of  the  negative  re- 
sistance type,  the  selectivity  of  the  system  is  greatly  in- 
creased, the  gain  in  selectivity  becoming  more  pro- 
nounced the  lower  the  damping  of  the  incoming  wave. 
Three  distinct  operations  are  therefore  carried  on 
simultaneously  in  the  non-oscillating  state.  / — the 
high  frequency  currents  are  regeneratively  amplified ; 
2 — the  selectivity  of  the  system  is  increased;  5 — the 
amplified  high-frequency  currents  are  rectified  and  con- 
verted into  currents  of  telephonic  frequency. 

When  the  amplification  is  increased  beyond  a  cer- 
tain limit  the  system  passes  into  the  oscillating  state  and 
generates,  in  radio  circuits,  high-frequency  currents. 
In  this  state  it  is  applicable  to  the  uses  of  any  generator, 
and  because  of  its  simplicity  and  reliability  it  is  particu- 
larly applicable  to  the  heterodyne  receiving  system.  By 
far  the  most  interesting  application  is  that  of  the  "self- 
heterodyne"  in  which  the  same  circuit  and  tube  perform 
simultaneously  the  functions  of  generator  of  the  local 
frequency,  amplifier  of  the  incoming  high  frequency 
and  rectifier  of  the  beat  current  to  produce  currents  of 
audible  frequency  in  the  telephones,  at  the  same  time 
giving  the  increase  in  selectivity  inherent  in  regenerative 
amplification.  All  these  operations  go  on  simultan- 
couslv  in  the  same  system  with  a  single  tube  and  out  of 
it  all  comes  a  signal  5000  times  as  strong  as  the  signal 
given  by  a  simple  audion  circuit  with  a  chopper,  and 
far  less  subject  to  the  disturbing  influence  of  static  and 
interfering  signals. 

On  account  of  the  verj'  fortunate  combination  of 
sensitiveness  and  simplicity,  its  effect  on  the  art  was  im- 
mediate. The  amplifying  feature  made  possible  trans- 
oceanic signaling.  The  self-heterodyne  feature  con- 
tributed ver}-  largely  to  the  change  from  spark  to  con- 
tinuous wave  systems.  The  generating  feature  has 
been  responsible  for  the  development  of  carrier  wave  or 
wired  wireless  signaling.  And  this  progress  can  be  at- 
tributed, not  to  any  carefully  preconceived  ideas,  but  to 
the  versatile  properties  of  the  regenerative  circuit  and 
the  luck  that  led  to  its  discover}^ 


April,   1921 


THE  ELECTRIC  JOURNAL 


155 


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o 


1982 — Reconnecting  Induction  Motor 
— I  have  been  using  the  tables  of  A. 
M.  Dudley,  and  recently  I  had  a  pair 
of  motors  to  be  changed  from  three 
to  two-phase,  at  the  same  voltage, 
namely  220  volts.  They  were  four 
pole  motors  with  1750  r.  p.  m.  at  full 
load  on  a  60-cycle  circuit.  They  were 
connected  two  parallel  star,  and  had 
54  coils.  According  to  the  tables  they 
will  not  reconnect  for  satisfactory 
operation  on  two-phase  at  the  same 
voltage,  but  another  electrician,  con- 
nected them  in  two  parallels  and  cut 
out  two  coils  and  they  claim  that  the 
change  is  giving  satisfactory  results. 
Now  what  I  want  to  know  is  this,  just 
what  is  happening  in  those  motors 
and  what  are  their  new  operating 
characteristics.  t.i.m.    (p.\.) 

The  two  coils  were  cut  out  so  that 
there  would  be  no  circulating  currents 
due  to  uneven  number  of  coils  in  the 
parallel  circuits.  This  increased  the  field 
strength  in  the  ratio  of  54  to  52.  When 
using  the  same  windine  and  changing 
from  three-phase  to  two-ohase.  the  volt- 
age should  be  reduced  in  ratio  of  i  to 
1.22  or  the  number  of  coils  increased  in 
the  same  ratio  when  the  same  voltage 
is  used.  From  this,  the  motor  is  now 
connected  with  a  field  54/52X1.22  or 
1.27  times  as  strong  as  before.  This  will 
increase  the  core  loss  and  pull  out 
torque  and  decrease  the  power  factor 
and  efliciency  to  lower  values  than  be- 
fore, depending  on  the  saturation  and 
the  distribution  of  losses  in-  the  motor. 
The  practice  of  cutting  out  coils  is  not 
recommended  for  first-class  work,  but 
can  be  done  to  advantage  in  emergency 
where  time  and  service  are  of  more 
value    than    performance.  c.w.k. 

1983—  .A.RM.\TURE  Connection.s— Given, 
a  25  hp,  shunt  motor,  no  volt,  300 
r.  p.  m.,  number  of  slots  =  80,  number 
of  commutator  bars  =  160.  number 
of  poles  =  6,  thickness  of  brush  =  2 
commutator  bars,  coils  formed  of  two 
separate  single-turn  coils  placed  in 
slots  1-14  giving  four  conductors  per 
slot  as  in  Fig.  (a).  I  judge  such  a 
winding  to  be  a  duplex  w-ave  winding 
and  the  proper  method  of  connections 
to  commutator  to  be  as  in  Fig.  (b). 
Kindly  indicate  if  assumptions  in  Fig. 
(b)  are  correct.  What  would  be  the 
effect  if,  instead  of  connecting  as  in 
Fig.  (b)  the  connections  were  inade 
as  in  Fig.  (c).  The  above  remarks 
refer  to  a  motor,  which  has  recently 
been  rewound.  At  no-load  the  motor 
runs  at  a  speed  about  four  times  that 
on  name  plate  and  current  seems  to  be 
excessive.  I  am  unable  to  state  the 
action  of  motor  under  load.  .-Ml  con- 
nections to  field,  etc.,  seem  to  be 
correct  but  I  am  doubtful  of  the 
armature  connections  which  are  made 
as  in  Fig.   (c).  c.  s.    (querec) 

The  winding  connected  as  in  Fig.  (cl 
has  8  current  paths,  consisting  of  four 
independent  two  circuit  windings.     One 


starts  at  bar  /  goes  in  succession  to 
bars  53,  IDS,  157,  etc.,  finally  closing  on 
itself  after  connection  to  only  one- 
fourth  of  the  total  bars.  Other  circuits 
from  bars  2,  j?  and  4  do  the  same.  The 
winding  as  connected  in  Fig.  (b)  has 
four  current  paths,  consisting  of  two 
independent  two  circuit  windings.  One 
starts  at  bar  7,  goes  in  succession  to 
bars  ,55,  iop,  163,  etc.,  finally  closing  on 


FIGS.    1983   (a),   (b)   AND   (c) 

itself  after  connecting  to  only  one-half 
of  the  total  bars.  An  independent  cir- 
cuit starting  from  bar  2  does  the  same. 
If  the  commutator  connection  is  1-54- 
107-160  etc.,  the  winding  will  be  a  sim- 
ple two  circuit  winding.  Since  the 
speed,  when  connected  as  per  Fig.  (c), 
is  four  times  the  rated ;  and  since  the 
speed  would  be  approximately  inversely 
proportional  to  the  number  of  current 
paths,  it  is  evident  that  the  original 
winding  was  a  simple  two  circuit  wind- 
ing, and  that  the  armature  connections 
should  be  1-54-107-160.  Reconnect  it  in 
this  way.  When  connected  as  per  Fig. 
(c)  the  no-load  current  would  be  ex- 
cessive, partly  due  to  higher  no-load 
losses  at  the  higher  speed,  and  also  be- 
cause probably  there  would  be  some 
circulating  current  between  the  various 
circuits.  .•Mso  the  brushes  are  not  wide 
enough  for  the  winding  shown  in  Fig. 
(c).  M.    s.    H. 

19S4— C.\R  Wheels,  Rails  and  Brakes 
— Has  the  experiment  of  shaping  car 
wheels  and  rails  to  fit  one  another  as 
shown  in  Fig.  (b)  ever  been  tried,  and 
with  what  success?  Is  the  coeflicient 
of  friction  between  a  wheel  and  a 
rail  less  when  the  area  of  contact  is 
small  as  in  Fig.  (a)  than  it  is  when 
the  area  is  large?  Docs  a  narrow 
fiangeway  in  a  brake  shoe  unduly  grip 
the  wheel  and  cause  it  to  slide,  even 
when  the  radial  brake  shoe  pressure  is 
moderate?  G.  F.  s.  (mass.) 

Better  results  have  been  obtained  with 
the  conical  tread  car  wheel  shown  in 
Fig.  (a),  both  in  experiments  and  actual 
practice  than  with  car  wheels  shaped  to 
fit  the  rails  or  vice  versa.  Tread  coning 
practically  compensates  for  the  increas- 
ed length  of  the  outer  rail  on  curves. 
As  the  outer  wheel  flanges  crowd 
against  the  rail,  the  inner  wheels  travel 


on  the  smaller  diameter.  When  treads 
become  grooved,  or  when  the  coning  is 
worn  down,  the  wheels  should  be  trued 
on  a  lathe  or  discarded.  Grooved  wheels 
cause  derailment  on  frogs  and  increase 
tractive  resistance  on  curves.  The  co- 
efficient of  friction  is  approximately  in- 
dependent of  the  area  of  contact,  except 
in  cases  of  fibrous  materials,  in  which 
case  the  coeflicient  increases  with  area 
of  surface  contact.  The  coefficient  of 
friction,  however,  is  materially  affected 
by  the  pressure,  speed,  degree  of 
smoothness  and  condition  of  the  sur- 
faces, temperature,  etc.  With  car  wheels, 
rails  and  brakes  it  is  a  question  of  safe- 
ty, expense  and  wear,  since  the  coeffi- 
cient of  friction  is  practically  independ- 
ent of  the  area  of  contact.  The  principal 
objection  to  shaping  the  rail  to  fit  the 
conical  tread  of  the  wheel,  as  shown  in 
Fig.  (b),  is  the  increased  danger  in 
spreading  the  rails.  After  rails  have 
been  in  service  for  sometime  they  grad- 
ually wear  down  to  this  form  and  it  is 
common  practice  to  change  the  rails 
about  or  replace  them.  It  is  quite  obvi- 
ous that,  with  a  rail  in  such  a  condition, 
when  the  flanges  of  the  wheels  on  one 
side  crowd  against  the  rail,  the  center  of 
pressure  on  the  other  rail,  falls  inside  of 
line  C  drawn  through  the  center  of  the 
rail ;  furthermore  a  force  /-",  the  hori- 
zontal component  of  load  pressure  L, 
due  to  angle  a,  tends  to  push  the  rail 
outward.  The  narrow  flangeway  in  the 


(al  lb) 

HGS.  1984 — (a)  and  (b) 

brake  shoe  is  not  designed  to  grip  the 
wheel  so  as  to  cause  it  to  slide.  The 
iTioment  the  wheel  slips  the  coefficient  of 
static  friction  ceases  to  act  and  its  place 
is  taken  by  a  very  much  smaller  coefli- 
cient of  sliding  friction.  The  flangeway 
increases  the  wearing  surface  and  the 
life  of  the  brake  shoe.  As  the  brake  shoe 
wears  away  quite  easily,  all  gripping 
effect  of  the  flangeway  soon  disappears. 

M.    M.    B, 

1985 —  Permanent  Magnets  — About 
how  much  is  the  flux  density  per  sq, 
in.  in  permanent  magnets,  such  as 
used  in  watthour  meters  ? 

E,  s,  (mich.) 
The  strength  is  approximately  25  000 
lines    per    sq.    in.      The    strength    varies 
with  the  different  types  and  with   indi- 
vidual magnets  of  the  same  type. 

A.  R.    R. 


iS6 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  4 


THE 
ELECTRIC 
JOURNAL 


le    purpose    of    this    sectiOD    is    to    present 

cepted  practical  methods  used  by  operating 

companies    throughout    the    country 


The   co-operation   of  all   those   interested    in 

operating  and  maintaining  railway  equipment 

is    invited.      Address    R.    O.    D.    Editor. 


APRIL 

1921 


First  Aid  for  Electrical  Injury 


In  and  about  the  shops  and  car  barns  of  electric  railways 
there  is  always  present  the  danger  of  injury  to  employees  by 
being  burned  or  shocked  by  electricity  from  the  trolley  or  third 
rail,  or  from  the  various  test  circuits  used  in  connection  with 
the  overhauling  and  repairing  of  the  equipment.  Such  accidents 
as  the  result  of  carelessness  or  ignorance  will  happen  in  spite  of 
the  many  safety-first  precautions,  and  first  aid  helps  should  be 
provided  that  will  relieve  sufTering  and  in  some  cases  may  save 
a  life. 

The  importance  of  this  work  is  fully  appreciated  by  soine 
of  the  larger  operating  companies  who  have  established  special 
medical  departments  in  charge  of  a  trained  attendant,  which  are 
located  in  the  shops  as  a  part  of  their  organization.  To  the 
smaller  companies  who  cannot  afford  to  maintain  such  a  depart- 
ment, the  following  suggestions  are  made  to  provide  the  funda- 
mentals to  take  care  of  emergency  cases  of  accidents  due  to 
electrical  injury. 

IMBST  AID  CABINET 

In  order  to  take  care  of  surface  burns  such  as  result  from 
coming  in  direct  contact  with  an  electric  arc  or  flash  of  any 


IIG.    I — FIRST   AID  C.-\BINET 

kind,  a  first  aid  cabinet,  such  as  shown  in  Fig.  i,  can  be  secured 
and  maintained  at  a  nominal  cost.     This  cabinet  contains  the 
necessary  material  to  give  first  aid  to  burns  and  other  injuries 
and  in  addition  has  simple  remedies  for  cramps,  headaches,  etc. 
The  size  and  equipment  of  this  outfit  can  be  modified  to  suit 
local  conditions.     It  should  contain  the  following  equipment:— 
Bottle    of    carron    oil*     (equal    parts    linseed    oil    and    lime 
water)  ;   bottle  of  aromatic  spirits  of  ammonia;   bottle  of  gasoline; 
bottle  of  liquid   soap;   bottle  of  cramp  cure;   bottle  of  tablets  for 
cold;  Lottie  of  tablets  for  headache;  bottle  of  iodine;  bottle  of  eye 
wash;  medicine  dropper;  rolls  of  cotton;  bandages;   adhesive  plas- 
ter; pair  of  scissors;  tourniquet;  small  basin;  paper  spoons;  paper 
cups. 

TEEATMENT  FOE  SUEFACE  BUENS 
The  following  gives  briefly  the  steps  to  be  taken  in  render- 
ing first  aid  to  such  injury  :^ — 

1 — Wash    the    injured    part    with    gasoline    until    thoroughly 
clean. 

2 — Apply  the   carron   oil,   or   treated   vasaline,    on   a  piece   of 
gauze  and  apply  to  the  burned  member. 

3 — Wrap  carefully  with  the  gauze  bandage. 
4 — Secure    bandag«    by    means    of    small    strips    of    adhesive 
plaster. 


RESUSCITATION   FROM  ELECTRICAL  SHOCK  BY  MEANS   OF 
ARTIFICIAL  RESPIRATION 

It  sometimes  happens  that  the  workman  gets  in  contact 
with  an  electric  circuit  and  is  badly  shocked.  In  this  case  quick 
action  is  necessary.  For  this  reason,  every  employe  should  be 
able  to  apply  artificial  respiration  at  once,  as  any  delay  is 
dangerous.  Such  accidental  shocks  seldom  result  fatally  if  the 
victim  is  aided  immediately  and  the  efforts  at  resuscitation  are 
continued.  If  the  body  is  in  contact  with  the  live  conductor,  a 
dry  stick  of  wood  or  a  dry  piece  of  clothing  should  be  used  to 
remove  the  conductor  or  roll  the  body  to  one  side.  If  the  body 
is  in  contact  with  the  earth,  any  loose  or  detached  piece  of 
clothing  may  be  seized  and  used  without  anv  d.iiis-'cr  to  draw 
the  body  away  from  the  conductor. 

Summon  the  doctorAvithout  delay. 

DIBECTIONIS 

1 — The  man  is  laid  upon  his  stomach,  face  turned  to  on© 
side  so  that  tho  mouth  and  nose  do  not  touch  the  ground. 

2 — Tho  patient's  arms  arc  extended  above  his  head.  His 
mouth  is  cleaned  of  mucus,  blood,  serum,  tohacco.  chewing  gum, 
false  teeth,  etc.,  by  a  stroke  of  the  finger. 

"S — The  operator  kneels,  straddling  the  patii-nt's  hips  and 
facing  his   head,   as   shown   in   Fig.   2. 


4^..     '^y'--" 


FIG.   2 — APPLYING    ARTIFICIAL    RESPIRATION 

4 — The  operator  places  his  fingers  parallel,  upon  the  lowest 
ribs  of  the  patient,  and  throws  his  own  body  and  shoulders  for- 
ward, so  as  to  bring  his  weight  heavily  upon  the  lowest  ribs  of 
the  patient.  This  downward  pressure  should  occupy  about  three 
seconds  then  the  pressure  is  suddenly  released  for  two  seconds 
without' removing  the  hands.  Squeezing  out  the  air  in  this  man- 
ner creates  a  partial  vacuum,  and  on  release  of  pressure  the  «ir 
rushes  into  the  lungs,  due  to  the  elasticity  of  the  chest  walls 
causing  the  chest  to  expand, 

5 — Repeat  this  act  at  the  rate  of  about  12  times  a  minute-— 
the  danger  is  that  in  the  excitement  of  the  occasion  the  rate  will 
bo  too  rapid.  If  the  operator  is  alone  with  the  patient,  he  can 
adjust  the  rate  of  the  artificial  respiration  by  his  own  deep 
regular  breathing;  if  others  are  present,  a  watch  can  be  used  to 
advantage  to  regulate  the  rate.  In  all  cases  the  efforts  at  re- 
suscitation should  be  continued  at  least  1.5  to  •-  hours  or  until 
the  arrival  of  the  physician,  who  should  be  summoned  at  once. 
Any  evidence  of  returning  breathing  should  encourage  the  oper- 
ator to  continue  his  efforts.  Such  efforts  are  usually  successful 
within  2.5  minutes,  but  recoveries  have  occurred  after  more  than 
two  hours  unconsciousness 

6 While    the    artificial    respiration    is    being    carried    on    a 

second  party  may  pull  the  hair,  dash  cold  wator  in  the  face, 
loosen  the  clothing  and  collar,  and  hold  a  cloth  saturated  with 
aromatic  spirits  of  ammonia  near  the  nose.  Inflicting  pain,  such 
as  pounding  the  soles  of  the  shoes,  with  a  board,  slapping  and 
rubbing  the  arm.-;  and  legs,  pulling  the  tongue,  or  the  hair,  have 
a  quickening  effect. 

7 — No  stimulants  nor  liquids  of  any  kind  should  be  given 
by  mouth  while  the  patient  is  unconscious. 

8— Kmp  tack  the  crowd,  let  the  patient  have  air. 

JOHN  S.  DEAN 


The  Electric  Journal 


VOL.  XVIII 


May.  1921 


No.  5 


The  National  Electric  Light  Association 

MARTIN  J.  INSULL 

President, 
National  Electric  Light  Association 

THE    44TH    ANNUAL    CONVENTION  of  the 
National  Electric  Light  Association  will  meet  in 
Chicago    from  May  31st  to  June  3rd    inclusive. 
At  this  Convention  will  be  outlined  and  discussed  ways 
and  means  for  promoting  the  purpose  of  the  Association 
"to  advance  the  art  and  science  of  the  production,  dis- 
tribution and  use  of  electrical  energy  for  light,  heat  and 
power,  and  for  public  ser- 
vice. ' '    In  carrying  out  this 
purpose  the  Association  has 
always  received  the  assist- 
ance and  advice  of  the  lead- 
ers in  the  industrj'.     Dur- 
ing the  present  administra- 
tive year  the  work  has  been 
carried  on  as  heretofore  by 
the  general  and  special  com- 
mittees of  the  accounting, 
commercial, public  relations 
and  technical  national  sec- 
tions of  the  Association  un- 
der the  immediate  direction 
of  their  respective  organiza- 
tions and  the  general  direc- 
tion   of    the    Association's 
Public  Policy    and    Execu- 
tive   Committees    and    the 
headquarter 's  staff.  In  gen- 
eral the  work  of  the   Nat- 
ional   Sections    covers    all 
branches   of  the    industry, 
not  only  as  to  its  immedi- 
ate  necessities  and  to  the 
ever-increasing    variety    of 
use  for  electrical  energy  but 
for  a  more  efficient  public 
service    and    a    far  greater 
development      of      the     '  industry      in       the      future. 
These     matters     of     so     vital     importance     to      the 
commercial  and  social  development  of  the  nation  will 
be    fully    reported    on    and    discussed    at    the    com- 
ing  Convention.     During   the    life   of   the   Association 
not  only  its  members  but  also  the  public  have  benefited 


Midc 


these  appliances  has  been  studied  until  through  the 
various  branches  of  industry,  including  manufacturers, 
jobbers,  contractor-dealers  and  Central  Stations,  these 
labor  saving  devices  and  electric  service  are  daily 
brought  to  the  business  and  home  life  of  the  nation. 

Through  its  work,  the  Association  has  been  one  of 
the  factors  in  developing  the  industrial  productivity  of 
the  countiy  and  the  comfort  of  its  citizens.     By  the  de- 
velopment of  transmission  and  distributions  systems  the 
country  is  surely  and  rapidly  being  covered  by  a  net- 
work of  lines  cariying  electrical  energy  to  the  smallest 
hamlet  and  giving  to  it  the 
same  class  of  service  that 
was   enjoyed   only  by   the 
larger  cities  a  few  years  ago. 
During  the  previous  ad- 
ministration, President  Bal- 
lard,   vice  -  president    and 
general    manager     of     the 
Southern  California  Edison 
Company,    brought  to  the 
Association  the  vision  and 
energy  of  the  great  West. 
Through  his  efforts  the  ac- 
tivities  of  the   Association 
were  largely  increased  and 
expanded    with    additional 
benefits  to  the  public  and 
the  industry.  The  establish- 
ment at  headquarters  of  a 
service  department,  a  pub- 
licity  department    and   an 
engineering     department 
added  greatly  to  the  service 
that    the   Association    was 
giving  to  its  members.  The 
partial  de-centralization  of 
the  work  by  the  creation  of 
thirteen  geographic  sections 
was  arranged  for  and  put  in- 
to effect.    This  enables  the 
several     'sections    of     the    country,    having    problems 
peculiar  to  theinselves,  to  work  actively  toward  their 
solution   as    well   as   to   carry   on    in   their   geographic 
division  the  general  activities  of  the  Association.     The 
creation  of  the  new  national  public  relations  section  to 
brinsf  about  a  better  understanding  between  the  public 


MARTIM  J.  INSULL 

V'icc-President 
Ic  West   Utilities  Company 


by  Its  work.  It  has  attacked  and  solved  the  problems  and  the  industry  was  formally  authorized  at  the  Pasa- 
tl;at  have  led  to  greater  efficiency  in  the  production  and 
distribution  of  electrical  energy-  with  a  consequent  im- 
provement of  service  at  a  decreasing  cost;  the  more 
general  application  of  electrical  energ}'  to  the  nation's 
business  and  home  life,  with  a  consequent  development 
of    the    necessary    appliances.     The    merchandising   of 


dena  Convention.  Since  that  time  Mr.  M.  H.  Ayles- 
worth  has  been  appointed  executive  manager  of  the 
Association  to  take  active  charge  of  working  out  these 
new  plans  under  the  direction  of  the  public  policy  and 
national  executive  committees  of  the  Association.  To 
the  best  of  its  ability  the  present  administration  has  en- 


158 


THE  ELECTRIC  JOURNAL 


\ol.     .Will,     .\"( 


deavored  to  carry  out  these  plans  and  policies  inaugur- 
ated by  President  Ballard  and  which  have  met  with  the 
hearty  support  of  the  membership  of  the  Association. 

At  the  beginning  of  this  Association  year  the  de- 
mand for  electric  service,  greater  than  at  any  time  in 
history  and  in  excess  of  the  existing  generating  ca- 
pacity, the  difficulties  of  raising  the  necessary  capital  to 
provide  for  this  demand  and  the  question  of  a  better 
understanding  as  between  the  industry  and  the  public 
seemed  to  be  of  paramount  importance.  Therefore, 
during  this  administrative  year  a  veiy  considerable 
amount  of  attention  and  effort  has  been  given  to  pro- 
moting this  better  understanding.  Millions  of  pieces  of 
literature  have  been  distributed  by  direct  mailing  to 
member  companies'  customers.  A  national  good  will 
advertising  campaign,  in  which  all  branches  of  the  in- 
dustry have  co-operated  magnificently,  has  resulted  in 
hundreds  of  good  will  messages  appearing  in  national 
popular  magazines,  the  daily  press  and  in  trade  jour- 
nals. Co-operation  between  the  Association  and  the 
Investment  Bankers  Association  has  resulted  in  hun- 
dreds of  thousands  of  pamphlets  dealing  with  the  eco- 
nomic side  of  the  industry  being  placed  in  the  hands  of 
bankers  and  investors. 

Following  the  initiative  of  the  Association,  all 
branches  of  the  industry  are  working  together  towards 
the  end  that  the  public  may  have  a  better  understanding 
of  their  mutual  inter-dependence,  and  the  necessity  of 
the  industry  being  so  treated  that  it  can,  without  fail, 
give  the  public  the  service  which  it  demands  and  which 
is  so  necessary  in  the  development  of  the  nation's  busi- 
ness. 


Constructive  Suggestions  by  a 
Past  President 

R.  H.  BALLARD 

Past  President  ( igig-ipao') 
National  Electric  Light  -Association. 

THAT  we  are  striding  rapidly  along  in  the  new  era 
of  electrical  development  is  the  predominating 
impression  that  I  obtain  from  ever)^  point  in 
which  I  come  in  contact  with  the  activities  of  our  in- 
dustry. From  coast  to  coast  the  awakening  to  the  nec- 
essity of  turning  the  output  from  every  prime-mover — 
v,-ater,  coal  and  oil — into  electric  energy  has  taken  place. 
It  has  assumed  the  dignity  and  magnitude  of  a  great 
movement  of  the  American  people  for  conservation  of 
natural  resources,  the  stimulation  of  a  substantial  pros- 
perity, and  the  increase  of  community  and  national 
Vvealth. 

Because  the  people  are  comprehending  that  there  is 
a  limit  to  the  store  of  coal,  oil  and  natural  gas,  their  in- 
telligence centers  on  economical  use  of  what  yet  re- 
mains in  the  earth,  and  the  conversion  of  these  fuels 
into  electricity  is  the  one  answer.  Increasing  costs  of 
coal,  oil  and  gas  has  brought  the  reason  for  these  in- 
creases home  to  every  individual  consumer.  The  gaso- 
line shortage  was  a  vivid  object  lesson  to  every  auto- 
mobile owner. 


As  a  substitute  for  the  fuels  of  the  earth,  hydro- 
electric energy  is  the  only  possible  recourse,  so  far  as 
human  knowledge  has  advanced.  With  this  fact  firmly 
fixed  in  the  public  mind  comes  a  realization  of  the 
enormity  of  the  economic  crime  of  permitting  water 
1  ower  to  remain  in  undeveloped  and  wasteful  idleness. 
Already  the  effect  of  the  spreading  interest  in  electric 
construction  is  manifest  in  the  market  for  electric 
securities.  Both  bonds  and  stocks  in  these  utilities  are  ' 
stronger  than  in  other  lines,  and  selling  during  a  period 
of  stagnation  in  larger  quantities.  This  is  entirely  dif- 
ferent from  conditions  a  year  ago,  and  I  sincerely  be- 
lieve that  that  change  is  largely  due  to  constructive  edu- 
cational activities  of  the  National  Electric  Light  Asso- 
ciation, its  geographical  groups  and  the  Central  station 
companies  of  the  United  States  and  Canada. 

Bringing  the  consumers  of  electricity  into  partner- 
ship by  the  purchase  of  junior  securities  insures  to  the 
bond  holders,  or  mortgagees  of  the  property,  a  higher 
degree  of  safety  than  they  have  ever  enjoyed.  In  pro- 
jects where  the  customer- partners  are  coming  to.  own 
substantial  holdings  in  the  equity,  the  investor  knows 
that  failure  and  inefficiency  are  impossible,  and  this 
assurance  will  increase  as  consumer-ownership  in- 
creases. It  is  quite  reasonable  to  conclude  that  the 
number  of  local,  or  consumer-stockholders  will  come  to 
be  closely  scrutinized,  and  become  a  determining  factor 
in  the  purchase  of  public  utility  bonds  and  debentures 
by  financial  houses. 

In  presenting  the  advantages  of  becoming  owners 
of  junior  securities  to  their  consumers,  central  station 
companies  can  point  their  argument  by  calling  attention 
tc  the  "self-interest"  idea,  which  means  that,  in  the  final 
distribution  of  the  money  spent  for  new  electrical  con- 
struction, not  only  the  community,  but  each  individual 
who  composes  it  derives  a  direct  personal  profit.  The 
accumulative  value  to  a  community,  and  its  reflected 
value  to  each  inhabitant,  property  owner,  business  man 
?nd  laborer,  of  fifty  thousand  horse-power  of  electrical 
energ)'  developed  and  used  each  year,  is  forcefully  illus- 
trated by  a  statistician,  who  has  worked  it  out  on  the 
basis  of  the  construction  program  of  a  Pacific  Coast 
company.  He  finds  that  it  will  provide  service  to 
32  250  residences,  495  factories  and  will  provide  for  the 
irrigation  of  150  000  acres  of  new  lands.  The  actual 
expenditures  for  construction  and  development  of  these 
new  enterprises  will  be  approximately  $165  000  000  for 
residences,  $75000000  for  factories  (employing  20  000 
men),  and  $15000000  for  the  development  of  the 
Innds.  The  annual  yield  from  the  factories  in  manu- 
factured products  will  amount  to  $100000000  and  the 
jiroduction  of  crops  from  the  new  acreage  irrigated  will 
add  $30  000  000  a  year  to  the  wealth  of  a  community. 

Summarizing  the  several  classes  ot  benefits,  we  find 
that  50000  hydro-electric  horse-power  developed  calls 
for  a  total  expenditure  of  $45  000  000  for  power  plants 
and  distributing  lines,  stations  and  equipment  in  resi- 


May,   1 92 1 


THE  ELECTRIC  JOURNAL 


159 


dences,  factories  and  on  agricultural  lands  for  its  use. 
The  construction  of  residences,  factories  and  the  de- 
velopment of  lands  will  call  for  an  additional  annual 
expenditure  of  $205  000000  and  linally,  the  value  of  the 
manufactured  products  and  crops  produced  will  amount 
annually  to  $130000000,  the  grand  total  expenditure 
and  yield  amounting  to  $380  000  000  annually. 

During  a  recent  visit  to  the  principal  cities  of  the 
East  and  Middlewest,  I  had  occasion  to  meet  with  the 
officers  of  the  National  Electric  Light  Association,  and 
to  discuss  with  them  the  excellent  program  which  is  be- 
ing prepared  for  the  annual  convention  in  Chicago.  It 
is  constructive  in  every  aspect,  and  will  tend  to  broaden 
and  widen  the  scope  of  the  work,  which  we  endeavored 
to  inaugurate  at  Pasadena  in  May,  1920.  The  partici- 
pation by  the  people  in  the  ownership  of  their  electric 
utilities  is,  to  my  mind,  the  most  practical  answer  to 
our  industrial  problems.  More  power  means  more 
work;  more  work  means  more  production,  and  in- 
creased production  is  synonymous  with  National  pros- 
perity. 


The  Utilities'  Situation 

MILAN  R.  BUMP 

First  Vice-President. 
National  Electric  Light  Association 

THE  forthcoming  Convention  of  the  National 
Electric  Light  Association  at  Chicago  will  go 
down  in  the  history  of  the  industry,  I  believe,  as 
one  of  its  greatest  milestones.  The  work  of  the  year, 
which  culminates  in  this  Convention,  has  been  of  tre- 
mendous importance  to  the  industry  as  a  whole.  Fol- 
lowing the  aggressive  plans  adopted  by  the  previous 
administration  toward  an  awakening  of  all  branches  of 
the  electrical  industry  to  a  realization  of  their  mutual 
interests  and  interdependence,  the  work  of  this  year  has 
borne  fruit  in  actually  carrying  out  those  steps  essen- 
tial to  bringing  about  co-operation  and  to  establishing 
mutual  confidence  between  the  manufacturer,  the 
jobber,  the  central  station  and  the  banker. 

The  trials  of  the  War  period  have  not  been  without 
their  compensating  benefits.  The  developments  of  this 
period,  particularly  the  efforts  necessary  to  protect  the 
central  station  industry  through  increases  in  rates,  have 
brought  about  a  mutual  understanding  between  the 
public,  the  regulatory  bodies  and  central  station  com- 
panies that,  in  my  opinion,  have  placed  the  industry  ten 
years  ahead  of  the  standing  which  they  otherwise  could 
have  expected  to  have  in  this  respect.  The  realization 
today  is  general,  and  reaches  every  section  of  the  coun- 
try, that  the  public  are  as  vitally  interested  in  the  suc- 
cess of  the  public  utilities  which  serve  them  as  are  the 
stockholders  of  the  utilities. 

When  regulatory  bodies  were  created,  they  first 
conceived  that  their  function  was  to  take  away  from 
the  industry  everything  which  they  could  claim  for  the 
public,  with  the  idea  that  in  this  way  they  were  serving 
to  carry  out  the  spirit  of  the  acts  which  created  the 
regulatory  bodies.     It  was  later  realized  that  these  same 


acts  also  contained  clauses  which  placed  a  burden  upon 
them  of  seeing  to  it  that  the  utilities  as  going  concerns 
are  strong  enough  financially  to  serve  the  territory 
which  they  occupied  properly  and  to  render  adequate 
service  to  all  who  demanded  it.  The  War  necessities 
brought  this  phase  of  the  situation  acutely  before  the 
public  and  the  resultant  educational  effect  has  been  tre- 
mendous. 

The  financial  necessities  of  the  utilities  have  served 
likewise  to  bring  before  the  bankers,  the  manufacturing 
and  jobbing  industries  the  fact  that  they  are  just  as 
vitally  interested  in  the  financial  success  of  the  utilities 
as  they  are  in  their  own  success,  because  it  is  utterly  im- 
possible for  the  manufacturing  interests  to  thrive  unless 
the  public  utilities  are  at  all  times  in  sound  financial 
condition,  and  ready  to  take  on  all  additional  business 
which  can  be  created  in  their  territories. 

The  change  in  the  policy  of  our  Association,  under 
which  the  manufacturing  and  jobbing  interests  are  di- 
rectly recognized  in  its  membership,  has  been  another 
means  of  bringing  about  that  mutual  understanding 
which  is  essential  to  the  success  of  all  branches  of  the 
industry. 

It  is  believed  that  the  forthcoming  Convention  will 
stand  as  the  day  when  the  realization  of  the  mutuality 
of  all  concerned  in  the  success  of  the  industry  can  be 
regarded  as  complete,  and  it  will  be  left  for  the  coming 
years  to  develop  on  this  basis  such  methods  and  plans  as 
will  best  promote  the  mutual  good  of  all  concerned. 
Many  of  these  plans  are  already  under  way,  the  great- 
est being,  in  my  mind,  the  Good-Will  Campaign,  in 
which  all  interests  are  joined  with  the  central  station 
industry  through  our  Association  and  are  building  to- 
ward a  firm  and  lasting  foundation. 

It  has  always  been  the  claim  of  the  public  utility 
industry  as  a  whole,  and  particularly  of  the  electrical 
industry,  that  the  securities  created  on  going  public 
utilities  are  the  safest,  soundest  form  of  corporate 
security,  and  are  entitled  to  the  highest  rating  from  an 
investment  standpoint.  The  showing  of  stability  of 
earnings,  of  growing  demands  for  service  which  pre- 
clude the  possibility  of  overbuilding,  of  regulation 
v.'hich  both  controls  and  protects,  is  one  with  which  no 
ether  industry  of  which  the  writer  has  knowledge  can 
compete.  The  conditions  of  the  past  four  years  have 
put  the  acid  test  to  all  of  these  claims,  and  the  result  has 
been  an  absolute  proof  that  the  claims  are  founded  upon 
fact. 

This  being  the  case,  we  can  look  forward  with 
great  confidence  to  the  ability  of  the  industry  to  grow 
in  the  immediate  future  at  any  rate  necessary  to  keep 
u[)  with  the  legitimate  demands  for  service.  It  is  my 
belief  that  our  industry  will  not  only  prosper,  but  that 
it  has  so  many  attractions  that  it  will  continue  to  draw 
to  its  membership  the  very  highest  type  of  technical  and 
business  talent,  and  that  it  will  continue  to  be  regarded 
as  an  honor  to  be  connected  with  the  industry  and  to 
take  part  in  its  upbuilding. 


i6o 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


The  Manufacturer  and  the  N.  E.  L.  A. 

FRANK  VV    SMITH 

Second  Vice-President, 
Xational  Electric  Light  Association 

THE  increased  activities  of  the  National  Electric 
Light  Association  during  the  last  eighteen 
months  have  crystallized  the  long-evident  and 
growing  spirit  of  co-operation  between  the  several  fac- 
tors in  the  electrical  industry,  until  today  it  is  believed 
that  the  industry  is  united  in  its  effort  to  serve  the 
public.  Through  closer  affiliation  by  representation  on 
the  executive  committee  and  public  policy  committee 
of  the  Association,  as  well  as  through  geographic  sec- 
tions and  technical  and  other  committee  activities,  it  is 
expected  that  these  relations  between  the  different  ele- 
ments of  the  industry-  in  which  we  are  all  so  vitally  in- 
terested can  be  cemented  still  closer. 

The  Class  D  and  Class  E  membership  in  the 
National  Electric  Light  Association,  as  represented  by 
the  manufacturers  as  Class  D,  or  company  members, 
and  Class  E,  or  individual  members,  has  always  been 
an  important  factor  in  the  affairs  of  the  Association, 
particularly  in  those  activities  dealing  with  technical 
and  commercial  matters,  which  have  been  such  an  im- 
portant part  of  its  work.  Contractor-dealers  and 
jobbers  throughout  the  countrj'  are  also  represented  in 
our  membership,  as  Class  F  and  Class  G  members,  and 
it  is  the  aim  of  the  Association  to  increase  this  repre- 
sentation largely  through  the  several  classes  of  member- 
ship, as  now  provided  in  the  constitution  of  the  Associa- 
tion. Self-interest  has  prompted  the  manufacturer  and 
jobber  to  participate  in  and  support  the  work  of  the 
Association,  just  as  the  same  self-interest  has  prompted 
the  central  station  membership  to  seek  that  participation 
and  support. 

The  purpose  of  the  N.  E.  L.  A.  is  "to  advance  the 
art  and  science  of  the  production,  distribution  and  use 
of  electrical  energy  for  light,  heat  and  power  for  public 
service,"  and  in  this  expressed  purpose  is  found  the 
basis  for  the  interest  of  the  manufacturer,  contractor- 
dealer  and  jobber,  as  well  as  for  the  central  station 
owners,  officers  and  employes,  for  it  cannot  be  gainsaid 
that  their  interest  is  common.  All  engaged  in  the  in- 
dustry have  as  their  primary  object  the  advancement  of 
electricity  in  public  service,  and  whether  this  end  is  at- 
tained by  perfecting  and  manufacturing  machinery,  by 
the  bettering  of  merchandising  methods  or  by  increas- 
ing the  efficiency  of  distribution  of  electrical  energ}- 
rnatters  little — the  ultimate  object  is  the  same. 

The  manufacturers,  as  represented  by  Class  D  and 
E  members,  are  aiding  the  Association  work  both 
financially  and  through  their  personal  interest  and 
efforts  as  members  of  committees.  The  officials  and 
those  in  close  contact  with  the  work  of  the  Association, 
having  in  mind  the  plans  for  future  development,  are 
verv'  hopeful  of  a  continuation  of  this  co-operative  spirit 


between  the  several  classes  of  membership,  and  are  en- 
deavoring to  increase  these  "tie  lines"  until  we  have  a 
complete  and  comprehensive  "network"  system  for  the 
good  of  the  industry. 

There  seems  to  be  a  growing  appreciation  of  the 
fact  that  generating  and  distributing  machinery  and 
equipment  can  have  no  extended  market  unless  the  elec- 
tric light  and  power  companies  of  the  country  prosper 
and  progress  in  advance  of  general  manufacturing  and 
commercial  progress,  and  that  machineiy,  appliances 
and  other  equipment  dependent  upon  electrical  energy 
for  motive  power  necessarily  must  have  a  restricted 
field  unless  the  electric  light  and  power  companies  ex- 
tend their  fields  of  service.  Here  is  the  common  in- 
terest, and  with  this  common  ground  upon  which  the 
various  classes  of  membership  meet,  united  effort  is  be- 
coming more  pronounced  and  general. 

Financing  is  a  problem  in  every  branch  of  the  in- 
dustry which,  through  the  co-operative  efforts  of  the 
Association,  we  are  all  seeking  to  solve.  In  the  central 
station  branch  of  the  business,  financing  becomes  not 
only  a  problem  for  the  entire  industry  to  consider,  but 
also  one  which  can  be  solved  best  through  a  public 
understanding  of  the  future  of  the  industry  and  its  rela- 
tion to  the  civic,  commercial,  social  and  individual  pro- 
gress of  the  public.  It  is  the  issue  of  paramount  im- 
portance at  this  time  to  the  central  station  company  and. 
therefore,  to  the  entire  industry. 

Through  its  public  relations  section  and  its  public- 
ity department,  the  Association  is  endeavoring  not  only 
to  do  its  share  to  bring  about  a  better  and  closer  under- 
standing on  the  part  of  the  public  of  some  of  the  prob- 
lems, but  also  to  point  the  way  for  manufacturers,  con- 
tractor-dealers and  jobbers  to  be  of  assistance  in  aiding 
this  movement.  The  details  of  the  activities  of  the 
Association  in  the  "good  will"  campaign  and  other 
publicity  and  advertising  activities  of  the  publicity  de- 
partment are  well  known  and  have  been  treated  fully, 
and  the  executive  committee  and  officers  of  the  Associa- 
tion are  appreciative  of  the  wonderful  spirit  of  co-oper- 
ation manifested  by  the  manufacturing  members  in  its 
publicity  and  up-building  work. 

The  electrical  industry  is  a  tremendous  factor  in 
the  advancement  of  civilization,  and  those  connected 
v.'ith  it  in  any  branch  have  more  than  the  average  oppor- 
tunity for  rendering  service  to  the  public.  It  is  incum- 
bent upon  every  individual  connected  with  the  industr}- 
tc  further  its  development,  not  only  for  the  purely 
selfish  benefits  which  undoubtedly  will  be  derived,  but 
that  our  glorious  United  States  may  continue  to  be  the 
greatest  electrical  nation  in  the  world,  which  is 
synonymous  with  the  greatest  nation  in  the  world. 

We  are  all  looking  forward  to  the  future  develop- 
ment of  the  Association  for  broader  activities  and,  with 
an  ever-increasing  membership,  a  close  co-operation  be- 
tween the  different  classes  of  this  membership  is  essen- 
tial and  necessarv. 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


161 


The  Technical  Work   of  the  National 
Electric  Light  Association 

I.  E.  MOULPROP 

Chairman,  National  Technical  Section, 
National  Electric  Light  Association 

WHILE  the  National  Electric  Light  Association 
has  always  done  a  certain  amount  of  engi- 
neering work,  the  real  beginning  of  the  exist- 
ing technical  organization  was  made  when  the  "Com- 
mittee for  the  Investigation  of  the  Steam  Turbine"  was 
appointed  in  1903.  This  consisted  of  three  members, 
Messrs.  W.  C.  L.  Eglin,  then  Chief  Engineer  of  the 
Philadelphia  Electric  Company,  Chairman ;  Frederick 
Sargent,  senior  member  of  Sargent  &  Lundy,  Consult- 
ing Engineers,  Chicago;  and  A.  C.  Dunham,  President, 
Hartford  Electric  Light  Company.  From  this  rather 
modest  beginning  the  engineering  work  has  developed  to 
the  point  that  today  one  of  the  four  major  divisions  of 
the  National  Electric  Light  Association  is  devoted  en- 
tirely to  this  work. 

There  are  now  eight  general  committees  in  the 
Technical  National  Section,  comprising  over  300  of  the 
leading  engineers  in  the  utility  business,  and  represent- 
ing about  250  of  the  member  companies  who  are 
sctively  engaged  in  engineering  work  of  the  Association. 
The  new  constitution  adopted  at  Pasadena  last  year  also 
provided  for  technical  activities  by  the  thirteen  Geo- 
graphic Divisions.  Most  of  these  Geographic  Divisions 
have  already  organized  their  technical  sections  and  have 
appointed  committees  corresponding  to  those  of  the 
Technical  National  Section  which  are  interlocked  and 
work  with  the  national  committees.  In  this  way  it  is 
possible  for  almost  every  member  company  of  the 
Association,  no  matter  how  small  or  where  located,  to 
be  represented,  take  part  and  benefit  in  this  technical 
work. 

Some  people  have  wondered  why  an  association 
largely  commercial  should  attempt  so  much  technical 
work  and  if  it  could  not  just  as  well  be  done  by  the 
numerous  existing  engineering  associations.  If  this 
were  true,  there  would  be  no  excuse  for  the  existence  of 
the  Technical  Section  of  the  National  Electric  Light 
Association.  The  fact  that  this  activity  has  grown  froin 
a  committee  of  three  in  1903  to  its  present  proportions 
proves  that  there  was  a  need  for  this  work  which  was 
not  satisfied  by  the  existing  engineering  societies.  The 
v;ide  and  growing  demand  for  copies  of  reports  indi- 
cates that  this  work  is  well  done.  By  the  constitutions 
of  the  several  national  engineering  societies  they  cannot 
go  into  commercial  matters,  whereas  the  Technical  Sec- 
tion of  the  N.  E.  L.  A.  has  no  such  restriction.  It 
should  be  pointed  out  that  the  technical  work  of  the 
National  Electric  Light  Association  is  not  intended  to 
and  does  not  duplicate  work  which  the  national  engi- 
neering organizations  are  doing.  On  the  contrary,  the 
Technical  National  Section 'co-operates  with  the  vari- 
ous national  engineering  societies  and  in  general  con- 


tinues the  engineering  work  of  the  former,  carrying  its 
application  to  the  utility  field. 

No  attempt  is  made  to  create  standards.  The 
Association  is  a  member  of  The  American  Engineering 
Standards  Committee  and  its  representatives  will  be 
found  on  practically  all  committees  of  the  leading  engi- 
neering societies  where  the  work  being  done  affects  the 
interests  of  the  Association.  In  fact,  the  very  theory  of 
the  Technical  National  Section  calls  for  the  utmost  co- 
operation with  other  organizations  to  the  end  that  dupli- 
cation of  work  is  eliminated  and  all  parties  interested 
work  together  to  the  common  end. 


Some  Thoughts  in  Connection  with  the 
Sale  of  Stock  to  Customers 

JOHN  F.  GILCHRIST 

Vice-President, 
Gommonwealth  Edison  Company 

FINANCIAL  conditions  brought  about  by  the 
world  war  have  precipitated  a  situation  in  the 
public  utility  industry  which  was  fast  approach- 
ing when  the  war  broke  out,  and  which  would  probably 
have  become  acute  in  the  next  two  decades  following 
1914  had  there  been  no  war.  The  public  utilities  have 
leached  a  point  where  a  normal  annual  growth  of  ten 
percent  represents  a  very  large  amount  of  money  in 
yearly  income,  and  when  this  is  multiplied  by  four  or 
five  in  order  to  arrive  at  the  annual  capital  requirements 
to  take  care  of  such  an  increase,  the  figure  at  the  present 
time  is  one  of  striking  proportions.  A  simple  compu- 
tation will  indicate  to  the  most  superficial  investigator 
what  a  tremendous  annual  sum  the  compounding  of 
these  increases  will  necessitate  twenty  years  from  now. 

The  conclusion  which  anyone  will  reach,  who  has 
given  much  thought  to  the  matter,  is  that  a  situation  is 
being  approached  rapidly  in  which  it  will  be  absolutely 
necessary  to  turn  to  the  people  who  are  being  benefited 
by  the  utility  service,  to  provide  a  considerable  portion 
ot  the  money  which  is  essential  for  plant,  in  order  that 
any  given  territory  may  be  served.  A  few  years  ago  it 
would  probably  have  been  thought  impossible  to  pro- 
vide the  required  money  in  this  way,  but  a  study  of  the 
comparatively  small  amount  per  customer  or  per  in- 
habitant which  this  would  amount  to,  and  experience 
in  developing  utility  company  customers  as  stock- 
holders, have  resulted  in  the  conclusion  that  this  is  a 
very  practical  and  satisfactory  method  of  financing,  and 
not  too  difficult  of  accomplishiuent. 

So  common  has  this  method  become,  and  so 
general  has  been  the  experience  with  it,  that  to  describe 
the  slight  variations  of  inethods  employed  by  different 
companies  is  not  of  special  interest,  but  some  thoughts 
may  be  presented  the  consideration  of  which  will  be 
profitable  to  those  interested  in  this  work. 

In  all  of  these  stock  sales,  the  best  results  have 
been  obtained  from  the  work  of  employees  from  all  de- 
partments of  the  company  offering  the  stock,  who  were 
stirred  to  enthusiasm  bv  interest  in  and  loyalty  to  their 


l62 


THE  ELECTRIC  JOURNAL 


Yo\.  XVIII,  No. 


company,  b}-  desire  to  familiarize  themselves  with 
financing  methods,  and  by  the  opportunity  offered  to 
earn  some  extra  money.  However,  most  managements 
have  found  that,  notwithstanding  these  inducements,  it 
is  a  great  problem  to  secure  sustained  interest  on  the 
part  of  employees  so  that  they  will  work,  and  this  con- 
dition has  resulted  in  the  employment  of  what  might 
be  known  as  "circus  methods",  nameh',  competitions 
and  various  plans  to  make  a  game  of  the  sale.  Those 
in  charge  have  realized  that  these  methods  could  not 
prevail  indefinitely,  and  have  diligently  sought  for 
other  means  of  maintaining  sales  in  high  volume  and 
v/ithout  unreasonable  cost. 

An  organization  which  may  prove  to  be  perma- 
nently satisfactory  may  be  developed  by  placing  in  the 
company's  territory  a  skeleton  organization  of  from 
three  or  four  to  twenty-five  or  more  men,  according  to 
the  size  of  the  territory,  who  will  be  paid  salaries  and  a 
small  commission,  and  who  will  devote  all  of  their  time 
t'-  the  sale  of  securities.  These  men  will  not  only  sell 
vigorously  themselves,  but  will  be  in  charge  of  stock 
sales  in  a  limited  territory.  Under  each  of  these  men 
will  be  placed  a  number  of  the  regular  company  em- 
ployees, on  the  basis  of  perhaps  twenty  regular  em- 
ployees to  each  full  time  stock  salesman,  these  em- 
ployees to  be  selected  principally  on  a  serious  agreement 
to  work  and  to  attend  classes  of  instruction  in  stock 
selling,  thus  preparing  themselves  to  become  efficient. 

This  plan  will  not  work,  however,  unless  it  is  ver}- 
carefully  arranged,  and  the  regular  company  employees 
who  are  expected  to  work  evenings  are  required  to  take 
the  matter  very  seriously,  to  do  conscientiously  a  certain 
amount  of  work  and  to  sell  a  certain  amount  of  stock 
each  week,  the  penalty  being  that  unless  they  do,  they 
cannot  hold  their  position  as  stock  salesmen. 

Such  an  arrangement  at  best  will  probably  be  fairly 
expensive.  If  maximum  results  are  desired,  the  writer's 
judgment  is  that  "circus  methods"  must  prevail  more  or 
less  for  a  year  or  two,  until  a  fair  percentage  of  the 
company's  customers  have  become  stockholders.  When, 
as  a  lesult  of  several  or  even  many  campaigns,  a  large 
number  of  stockholders  has  been  acquired,  it  will  be 
found  that  the  expiration  of  the  purchase  arrangements 
of  those  who  buy  on  time  will  be  scattered  throughout 
the  year.  Then  it  will  undoubtedly  be  possible,  by  sys- 
tematic work,  for  an  investment  department  of  modest 
size  to  develop  a  process  of  reselling,  both  to  those  who 
have  bought  for  cash  and  to  those  who  have  bought  on 
time,  so  that  the  annual  sales  of  stock  will  be  veiy  con- 
siderable and  will  grow  with  the  company's  growth. 

In  all  of  these  sales  of  stock  it  is  to  be  hoped  that 
figvues  will  soon  be  available  as  to  the  cost  of  collecting 
installments,  cost  of  advertising  and,  in  fact,  all  of  the 
costs  of  selling  and  getting  in  the  money.  It  will  thus 
be  possible  to  determine  in  how  small  payments  and 
ever  what  periods  of  time  it  will  be  desirable  to  sell 
stock.  When  sales  on  this  basis  first  began  to  be  made, 
the  periods   covered  were  quite  extended,  but  it  was 


found  that  a- large  amount  of  money  was  paid  in  cash, 
and  that  those  who  were  paying  on  installments  fre- 
quently came  in  later  and  paid  up  in  full. 

These  facts,  together  with  an  impatience  to  obtain 
the  money,  have  prompted  many  of  the  companies  to 
shorten  their  deferred  payment  period.  There  is  un- 
doubtedly much  business  to  be  obtained  by  adding  to 
the  plans  which  are  now  in  use,  a  plan  involving  a  very 
long  period  of  payment.  Some  differential  in  price 
will  have  to  be  made  in  such  a  plan,  or  perhaps  it  may 
be  offered  only  to  children  and  young  people,  on  the 
theory  that  they  cannot  pay  as  much  as  older  people, 
and  further,  that  they  may  not  have  the  same  reasons 
as  a  grown  person  for  desiring  a  fairly  short  period  of 
payment. 

Except  for  the  cost  of  handling,  there  is  no  par- 
ticular reason  why  a  plan  should  not  be  brought  out  to 
sell  stock  on  the  basis  of  $i.oo  per  share  per  month, 
added  to  the  lighting  bills.  This  might  do  even  with  a 
one  hundred  dollar  share,  but  such  a  policy  may  result 
in  the  practice  of  issuing  shares  of  less  than  $ioo  par 
value.  Such  a  long  term  plan  need  not  necessarily  infer- 
fere  with  the  sale  of  stock  on  the  other  basis  to  the  same 
person  or  to  some  one  in  the  same  family  and,  so  far  as 
the  writer  can  see,  the  only  difference  will  be  that  it 
will  open  up  a  vast  new  field,  for  the  person  who  now 
takes  one  share  at  $5  or  $10  per  month  could  probably 
be  induced  to  take  its  equivalent  in  shares  at  $1.00  per 
month. 

Another  matter  to  which  those  interested  in  selling 
stock  are  giving  thought  is  the  question  of  extending 
the  sales  organizations  to  take  in  employees  of  manu- 
facturers, jobbers,  dealers  and  contractors  in  the  elec- 
trical line.  There  are  many  reasons  why  these  people 
should  be  included.  Their  interests  and  those  of  the 
institutions  they  serve  are  identical  with  the  interests 
of  the  utilities;  in  fact,  it  may  be  said  that  they  have  a 
greater  interest  in  the  utilities'  ability  to  extend  than 
have  the  people  employed  by  the  utilities  themselves, 
as  the  utilities  could  for  a  short  time  thrive  abundantly 
without  growth,  whereas  growing  utilities  are  essential 
to  the  very  life  of  the  dependent  businesses.  There- 
fore, it  would  seem  that  such  organizations  should  not 
cnly  be  willing  that  their  people  should  assist,  but 
should  take  the  initiative  and  provide  executives,  not 
only  to  organize  their  own  forces  in  this  work,  but  to 
offer  a  serv^ice  to  the  backward  utilities  who,  because  of 
small  size,  lack  of  initiative  or  appreciation  of  the  possi- 
bilities, are  not  already  helping  themselves. 

The  indirect  advantages  to  the  employees  are  sub- 
stantial. An  opportunity'  is  offered  to  earn  in  their  lei- 
sure hours  a  large  percentage  of  their  monthly  pay,  a 
knowledge  of  financing  and  of  the  advantages  and 
possibilities  of  saving  is  developed,  and  last  and  great- 
est, an  appreciation  of  the  size,  dignity  and  usefulness 
of  their  industr\'  and  a  spirit  of  co-operation  is  ac- 
quired, which  will  be  of  great  value  to  the  entire 
iiidustrv  and  everv  individual  in  it. 


May,  1921 


THE  ELECTRIC  JOURX.U. 


163 


To  that  great  division  of  industry  which  includes 
all  of  the  utilities  and  all  businesses  in  any  way  de- 
pendent upon  them,  there  is  no  more  pressingly  impor- 
tant question  today  than  that  of  the  sale  of  utility 
securities  to  the  public  who  depend  on  the  services 
rendered  bv  these  utilities. 


Conserving  Capital  and  Natural 
Resources 

EDWIN   D.   DREYFUS 

Engineer,  Pittsburgh,  Pa., 

THE  remarkably  increasing  development  of  large 
electric  power  systems  brings  up  such  ques- 
tions as  that  of  generating  power  at  the  source 
and  transmitting  the  energy  to  the  markets  over 
long  distance  transmission  lines.  Even  popular 
magazines  like  the  Scientific  American  and  the  Literary 
Digest  quite  recently  have  made  this  development  the 
theme  of  certain  technical  articles.  A  very  important 
investigation  sponsored  by  the  U.  S.  Geological  Survey, 
now  well  under  waj',  contemplates  ascertaining  the  eco- 
nomic features  of  a  super  power  zone  system  for  the 
metropolitan  district  of  the  Eastern  border  extending 
from  Maine  to  Washington,  D.  C.  and  stretching  back 
150  miles  from  the  coast.  Conservation  of  course  is  the 
object  sought,  and  the  study  will  embrace  all  power  re- 
quirements within  that  area,  including  the  gradual  elec- 
trification of  the  existing  steam  railroads  and  the  bring- 
ing about  of  complete  co-ordination  of  the  present  sys- 
tems of  electric  power  supply.  To  the  degree  that  the 
project  shows  improved  economies  in  the  use  of  our 
natural  resources,  its  promotion  will  be  accelerated. 
Tut  the  amount  of  fresh  capital  required  to  establish 
such  an  enterprise  in  its  entirety  will  probably  cause 
progress  in  this  direction  to  be  made  rather  slowly. 
Undoubtedly,  the  comprehensive  report  to  be  expected 
in  the  early  future  will  be  highly  profitable  and  instruc- 
tive to  students  of  central  station  development.  Mass 
production  and  long  distance  transmission  have  been 
the  dream  of  many  of  our  pioneers  in  the  electrical  in- 
dustry for  years.  Naturally  conditions  must  be  favor- 
able in  order  to  justify  these  ambitions.  Two  outstand- 
ing elements  control, — the  nature  of  competing  sources 
of  power  and  the  magnitude  of  the  load  in  comparison 
with  the  distance  to  be  transmitted.  Moreover,  if  it  is 
a  fuel  (coal  or  oil)  conversion  proposition  at  the  source, 
then  a  point  may  be  reached  where  the  carrying  charges 
on  the  transmission  line  investment,  together  with  the 
hne  losses  will  exceed  the  cost  of  freight  on  the  fuel. 
And  these  are  factors  whicli  appear  to  be  frequently 
overlooked  in  the  pofuilar  conception  of  the  problem. 
Obviously,  there  is  an  economical  radius  within  which  a 
given  amount  of  power  mav  be  taken  from  a  fixed  sta- 
tion. In  general  terms  it  will  require  demands  of  over 
50000  kilowatts  .at  high  load  factors  to  justify  trans- 
mission distances  of  100  miles  or  thereabouts.  There- 
fore, as  time  goes  on  and  there  is  more  intensifying  and 
concentratior  of   load,   long  distance   transmission    will 


come  more  and  more  into  use.  Local  conditions  will 
always  exert  their  influence  and,  where  good  fuel  is 
scarce  and  costly  or  where  large  and  inexpensive  water 
power  developments  are  assured,  we  will  find  the  build- 
ing of  long  distance  lines  vigorously  prosecuted,  as 
Western  experience  typifies.  The  striking  feature  of 
this  issue  of  the  Journal  is  the  emphasis  given  to  the 
long  stretches  of  transmission  lines  of  contiguous  power 
systems  which  provide  valuable  links  in  a  rapidly  grow- 
ing cross-country  power  service.  About  fifteen  percent 
additional  mileage  at  the  present  time  would  close  the 
gaps  and  thus  achieve  a  continuous  electrical  power  cir- 
cuit between  New  York  and  Chicago.  The  through 
connection  is  not  the  practical  attainment  sought,  but  is 
merely  an  incident  of  the  advantages  accruing  from  the 
lying-in  of  adjacent  systems.  Maps  of  these  systems 
might  easily  convey  the  impression  to  the  lay  mind  that 
energy  would  be  transmitted  from  one  end  of  the  inter- 
connected systems  to  the  other.  Long  reaches  of  con- 
nected transmission  lines  do  not  signify  long  distance 
delivery  of  power  but  in  essence  represent  a  closely  built 
up  industrial  area  in  which  central  power  is  a  conspicu- 
ous element. 

The  real  merits  in  the  tying-in  of  the  adjacent 
Ijower  systems  lies  in  economizing  in  the  installation  of 
spare  power  station  capacity  through  the  ability  to  draw 
upon  the  neighboring  utilities  in  case  of  emergency  and 
also  in  the  likely  improvement  ot  operating  conditions 
h}-  virtue  of  such  diversity  of  load  as  may  occur  between 
.idjoining  properties.  Furthermore,  voltage  conditions 
■•'.n.d  service  to  outlying  districts,  forming  the  points  of 
contact  between  two  systems,  are  thus  evidently 
bettered.  Owing  to  the  pressure  which  has  been  applied 
to  the  central  station  industry  by  the  increasing  power 
demands,  together  with  the  recently  restricted  flow  of 
new  capital,  most  facilities  of  the  utility  companies 
I'.ave  been  lately  worked  to  the  limit.  Hence,  sudden 
emergencies  necessarily  compel  very  prompt  action.  As 
<•'  practical  case  of  the  advantage  of  interlocking  sys- 
tems, we  might  refer  to  the  three  large  independent  sys- 
tems operating  throughout  Western  Pennsylvania, 
l-',astern  Ohio  and  the  Pan  Handle  of  West  Virginia, 
which  are  tied  in  at  several  points.  A  hurried  call,  say, 
lor  10  000  kilowatts  from  one  company  at  Pittsburgh 
may  only  be  satisfied  at  the  particular  time  by  rushing 
certain  reserves  of  the  second  company  into  service  at 
Canton,  Ohio,  and  making  virtual  delivery  over  lines 
of  the  third  comjiany  forming  the  connecting  link,  and 
ihe  reverse  or  a  different  combination  of  circumstances 
may  obtain.  What  actually  takes  place  in  accomplish- 
ing these  results  is  a  redistribution  of  the  loads  on  the 
various  power  stations  affected.  There  have  been  at 
tunes  as  much  assistance  as  45  000  kilowatts  temporarily 
given  by  one  company  to  the  other.  The  U.  S.  Govern- 
ment, during  the  latter  stages  of  the  world  war,  was 
\ery  active  through  the  Power  Section  of  the  War  In- 
(htstries  P.oard  in  the  planning  of  tying-in  of  neighbor- 
ing power  systems  and  particularly  those  that  were  serv- 


164 


THE   ELECTRIC  JOURNAL 


\oI.   X\III,   Xo. 


ing  munition  and  other  war  supply  establishments.  The 
large  question  in  this  particular  development  centers 
about  the  harmonious  co-ordination  of  the  systems  to  be 
hnked  together,  so  that  the  greatest  good  will  result, 
with  complete  equity  obtained  between  all  interested 
parties.  Impartial  analyses  will  point  the  way.  In  the 
East,  committees  have  been  appointed  with  just  such 
objects  in  view  and  certain  adjoining  companies  already 
have  quite  successfully  formulated  and  made  effective 
co-operative  working  arrangements.  Thus,  we  have 
seen  the  trail  blazed  and  may,  therefore,  expect  succeed- 
ing years  to  bear  abundant  evidence  of  activity  in  this 
direction.  No  doubt  even  broader  economic  policies 
v.'ill  follow. 


The  Use  of  Central  Station  Power  by 
Industrial  Plants 

BRENT   WILEY 

Industrial  Dept., 
Westinghouse  Electric  &  Mfg.  Company 

THE  use  of  electric  drive  in  industrial  plants  has 
increased  at  a  phenomenal  rate  during  the  last 
ten  years.  The  percentage  of  electric  horse- 
power to  total  primary  horse-power  is  now  about  55 
percent,  which  is  more  than  double  what  it  was  in  191 1. 
On  the  basis  of  a  normal  growth  of  industries  during 
the  next  five  years,  it  seems  reasonable  to  predict  that 
by  1926  industrial  plants  will  be  70  percent  electrified. 

Central  station  power  has  been  one  of  the  main 
factors  in  assisting  the  electrification  of  many  plants, 
particularly  those  of  small  capacity.  The  extent  to 
which  central  station  power  is  available  will  be  an  im- 
portant point  in  the  future  electrification  of  industries 
and  will  largely  influence  the  percentage  of  electrifica- 
tion as  existing  within  a  period  of  five  years. 

The  industrial  plant  load  is  doing  much  to  fill  in 
what  has  been  a  low  load  period  of  the  central  stations 
and  also  has  improved  the  load  factor.  A  few  years 
ago  at  least  75  percent  of  the  electric  energy  generated 
by  the  central  station  was  used  for  lighting  and  street 
railway  purposes.  At  present,  however  the  power  load 
predominates  and  in  man}'  cases  ranges  from  35  to  65 
percent  of  the  total.  This  is  very  encouraging  to  the 
central  station  companies,  and  they  feel  confident  re- 
garding their  future  growth  as  far  as  the  question  of 
demand  is  concerned.  From  the  power  user's  stand- 
point, this  will  depend  largely,  on  the  rehabilitation  of 
industrial  plants  which  are  using  drives  that  are  inade- 
quate and  in  a  badly  worn  condition,  and  later  addi- 
tional load  will  be  obtained  by  the  growth  of  the  in- 
dustry. 

From  the  standpoint  of  economy  the  small  indus- 
trial plant  cannot  compete  with  the  central  station  in 
cost  of  power,  and  with  the  price  of  coal  as  established 
during  the  last  few  years,  there  are  not  many  large 
plants  that  can  generate  power  as  cheaply  as  the  central 
station.     It  is  a  well-conceded  point  today  that,  with  the 


central  station  power  at  even  somewhat  higher  cost 
than  that  of  the  private  plant,  it  is  advisable  to  consider 
its  use.  Its  advantages  are  of  a  broad  character,  re- 
ducing first  cost  of  investment  in  the  plant,  elimfnating 
supervision  of  an  important  operating  item,  permitting 
more  attention  to  the  direct  processes  of  manufacturing, 
rnd  giving  a  definite  basis  for  distributing  and  analyz- 
ing power  costs. 

Regardless  of  what  might  have  been  the  situation , 
m  the  past,  the  central  station  today  is  developed  to  give 
reliable  service.  The  details  of  plant  construction,  the 
question  of  spare  units,  the  distribiiting  system  and,  in 
most  districts,  the  tie-in  circuit  system,  give  assurance 
of  continuity'  of  service.  The  question  of  rates  is  not 
so  much  of  a  problem,  because  practically  all  indefinite 
features  from  the  standpoint  of  both  the  central  station 
and  the  customer  are  being  eliminated.  Central  station 
power  load  has  now  become  a  reality  and  experience 
gives  the  power  companies  a  substantial  basis  for  esti- 
mating costs  and  enables  them  to  establish  rate 
schedules  on  a  basis  consistent  with  the  various  demand 
conditions.  Much  data  is  available  regarding  the  load 
icquirements  of  different  classes  of  industrial  plants. 
These  conditions  tend  to  a  more  definite  contract  and 
should  do  much  to  encourage  the  use  of  central  station 
power  by  the  larger  industrial  companies. 

Economy  of  operation  is  the  watchword  of  indus- 
try, particularly  at  this  period.  Every  industrial  plant 
should  have  its  production  costs  definitely  established 
tmd,  where  the  plant  generates  its  own  power,  a  close 
analysis  of  this  element  of  cost  should  be  made.  The 
price  of  coal  has  advanced  as  much  as  3CX)  percent  in 
fome  districts  and  labor  is  practically  double  what  it  was 
a  few  years  ago.  It  will  be  found  that  the  central  sta- 
tion rates  on  an  average  have  not  increased  proportion- 
ally during  the  last  several  years,  and  the  change 
is  quite  in  contrast  with  the  cost  of  power  as 
produced  by  private  plants.  This  is  made  possible 
by  the  expansion  of  the  central  station  and  by  the  better 
load  factor  conditions.  More  economical  sizes  ol  gen- 
erator units  installed,  and  more  economical  station  lay- 
outs, with  improved  designs  of  boilers,  distributing  sys- 
tems, etc.,  have  assisted  in  reducing  generating  costs 
almost  enough  to  make  up  for  the  increased  cost  of  coal 
and  labor. 

Further  improvement  in  the  central  station  will 
come  with  its  continued  growth ;  it  is,  therefore,  some- 
thing more  than  a  selfish  interest  on  the  part  of  the  in- 
dustrial plant  owner,  when  he  considers  the  use  of  cen- 
tral station  power  to  better  his  own  plant  conditions  and 
costs.  He  is  thinking  of  the  community  interests  and 
what  it  means  to  the  public  to  have  improved  power  ser- 
vice, including  greater  assurance  of  continuity  of  ser- 
vice and  reduced  cost,  all  of  which  are  made  possible 
only  by  the  opportunity  given  the  central  station  to 
grow.  The  central  stations  need  the  support  of  the  in- 
dustrial companies  and  engineers  and  in  return  have 
much  to  give. 


May,   1 92 1 


THE  ELECTRIC  JOURNAL 


165 


The  Pittsburgh  Power  Zone 

A.  II.  iMclNTIRE 

As  a  means  of  aiding  in  the  work  of  ihe  National 
Electric  Light  Association,  it  has  been  the  cus- 
tom of  the  Journal  to  publish  a  convention 
issue  about  the  time  of  the  annual  meeting  of  the  Asso- 
ciation including  discussions  of  the  subjects  of  most 
vital  interest  to  central  station  operating  men  at  the 
time.  The  present  issue  contains  numerous  contribu- 
tions of  this  nature  from  some  of  the  most  prominent 
engineers  in  the  central  station  industry,  including  five 
of  the  executive  officers  of  the  National  Electric  Light 
Association. 

Each  year  particular  attention  has  been  given  to 
some  recent  central  station  developments  which  seemed 
most  important  at  the  time.  For  1921,  it  was  found 
that  the  greatest  central  station  development  has  been 
in  the  Pittsburgh  district,  where  two  super  power 
plants,  each  designed  for  an  ultimate  generating  ca- 
pacity of  300000  kilowatts,  are  being  placed  in  regu- 
lar service,  with  accompanying  extensive  increases  in 
transmission  lines  and  substations.  Accordingly,  ar- 
rangements were  made  with  the  executives  of  these 
central  station  companies  for  full  descriptions  of  these 
installations  by  the  engineers  who  had  originated  and 
supervised  their  construction,  and  these  two  groups  of 
articles  appear  in  the  present  issue  of  the  Journal, 
along  with  other  articles  on  subjects  of  broad  general 
engineering  interest. 

Each  of  these  new  power  plants  is  located  on  a 
liver  affording  sufficient  condensing  water  for  a  300000 
kilowatt  installation.  In  addition  they  are  examples 
of  the  mouth-of-mine  type  of  station,  as  each  is  located 
adjoining  large  coal  fields  controlled  by  the  power  com- 
panies. Such  locations  are  desirable  from  two 
view  points.  They  eliminate  the  necessity  of  paying 
a  profit  to  coal  mining  and  transportation  companies, 
and  afford  added  insurance  of  continuity  of  service,  as 
there  is  no  possibility  of  interruption  of  the  fuel  supply, 
due  to  strikes  or  other  difficulties  on  the  regular  trans- 
portation lines.  There  is  also,  as  pointed  out  by  Mr. 
Bell  in  this  issue,  the  further  possibility  of  increased 
economy  due  to  the  continuous  use  of  a  uniform  grade 
of  fuel  whose  characteristics  can  be  thoroughly 
analyzed  by  the  operating  forces;  whereas  with  pur- 
chased coal  it  is  necessary  to  make  use  of  whatever 
fuel  the  railway  or  water  transportation  companies  are 
able  to  deliver. 

The  central  station  industry  as  a  whole  is  vitallv 
interested  in  the  development  of  these  mouth-of-mine 
super-power  plants  with  their  transmission  systems  and 
methods  of  interconnection,  as  discussed  in  detail  by  the 
officials  of  the  Duquesne  Light  Company  and  the  West 
Penn  Power  Company,  as  they  represent  a  definite 
effort  to  incorporate  the  most  advanced  present-da}- 
practice  in  power  plant  design.  At  the  same  time  the 
new  plants  at  Colfax  and  Springdale  are  essentially  dif- 
ferent  in   many   details   and   doubtless   much   valuable 


data  will  be  obtainable  by  comparing  the  operation  of 
two  such  plants,  both  using  the  water  from  the  same 
river  and  coal  from  nearby  veins. 

In  the  territory  between  J3oston  and  Washington 
the  government  has  been  making  a  survey  of  the  power 
situation  and  possible  improvements  therein.  This 
analysis,  which  is  soon  to  be  completed,  will  doubtless 
be  of  great  importance  as  a  forerunner  of  similar 
studies  in  other  districts.  Alany  of  the  present  Boston- 
Washington  power  plants  are  located  at  sea  level,  where 
abundant  condensing  water  is  available,  but  the  fuel 
must  be  transported  considerable  distances.  Coming 
westward  from  this  seaboard  super-power  zone,  there 
i-'  another  district  which  presents  corresponding  al- 
though different  problems.  In  the  Pittsburgh  power 
district,  where  an  interconnected  system  has  already 
begun  to  develop,  there  are  still  further  possibilities  in 
the  way  of  increased  economies,  both  of  generation  and 
construction,  as  exemplified  by  the  two  immense  power 
plants  now  being  placed  in  service.  Roughly,  the 
present  limits  of  the  Pittsburgh  power  zone,  based  on 
transmission  lines  already  in  existence,  extend  from 
East  of  Altoona,  Pennsylvania  to  about  the  middle  of 
Ohio,  and  includes  the  various  systems  beginning  with 
the  Penn  Central  and  Penn  Public  Service  on  the  East 
and  extending  to  the  American  Gas  &  Electric  and 
the  Doherty  properties  in  Ohio.  In  some  cases  numer- 
ous interconnections  already  exist;  in  others,  there  is 
actual  crossing  of  lines;  in  others  only  short  gaps  need 
to  be  bridged.  Part  of  this  power  is  being  transmitted 
r.t  132  000  volts,  and  over  100  miles  of  other  tower  lines 
have  been  constructed  for  ultimate  operation  at  this 
voltage,  with  132000  volt  transformers  and  circuit 
breakers  already  installed. 

An  idea  of  the  territory  included  in  this  zone  can 
be  obtained  by  reference  to  the  first  illustration  in  the 
article  by  Mr.  Humphrey  in  this  issue  of  the  Journal. 
In  this  territory  are  four  new  mouth-of-mine  super- 
power plants — Seward,  Springdale,  Colfax  and 
Windsor — the  last  named  being  the  only  one  to  gel  into 
service  before  the  end  of  the  war,  although  Springdale 
was  begun  under  government  supervision.  The  Colfax 
and  Springdale  plants  have  been  carrying  load  for  some 
months  and  the  .Seward  plant  is  about  readv  for  regu- 
lar operation. 

On  account  of  the  enormous  amount  of  war  orders 
placed  in  the  Pittsburgh  district  at  the  beginning  of  the 
Vv'ar,  the  then  available  generating  ecjuipment  eventually 
became  so  overloaded  that  the  Power  Section  of  the 
War  Industries  Board  was  placed  in  charge  of  the 
situation  to  avoid  confusion  and  delay  in  the  produc- 
tion of  essential  war  materials.  A  thorough  investiga- 
tion was  made  of  the  facilities  of  the  various  utilities 
and  the  possibilities  of  securing  a  greater  diversity 
factor  by  interchange  of  loads.  A  few  weeks  ago,  the 
War  Department  published  a  limited  edition  report  on 
"The  Power  Situation  during  the  War",  which  in- 
cluded an  analysis  of  the  power  situation  in  the  Pitts- 


1 66 


THE  ELECTRIC  JOURX.II. 


\'(il.   XVIII,  No.  5 


burgh  district.  From  this  report,  it  appears  that  the 
public  service  companies  of  this  district  alone  have  an 
installed  generating  capacity  of  considerably  over 
1  ooo  ooo  kilowatts.  In  addition  to  this,  the  report 
shows  an  estimated  present  generating  capacity  in  iso- 
lated power  plants  of  over  700000  kilowatts,  in  addi- 
tion to  about  800000  kilowatts  in  the  major  steel  com- 
panies, or  a  total  of  considerably  over  two  and  one-half 
million  kilowatts  as  the  generating  equipment  of  the 
entire  district. 

In  the  steel  industry  a  considerable  amount  of 
power  is  being  generated  by  the  utilization  of  waste 
heat  and  blast  furnace  gas,  which,  for  the  present  at 
least,  as  pointed  out  by  Mr.  S.  S.  Wales  in  this  issue, 
can  hardly  be  superseded  b)^  central  station  service. 
However,  many  rolling  mills,  wire  and  rod  mills,  tube 
mills,  ferro-alloy  electric  furnaces,  etc.,  do  not  have  the 
benefit  of  cheap  power  from  blast  furnace  gas,  and 
government  estimates  state  that  about  half  the  power 
ttsed  by  the  steel  companies  in  the  Pittsburgh  district 
is  produced  from  coal  burned  under  boilers.  This 
power  can  be  considered  as  prospective  central  station 
business. 

As  indicated  in  the  articles  by  Messrs.  McKinley 
and  Gadsby,  the  Pittsburgh  power  district  is  the  larg- 
est and  most  congested  industrial  district  in  the 
United  States  and  a  sufficiency  of  dependable  power  is 
a  vital  necessity  to  the  continued  development  of  the 
district.  In  addition  to  the  new  industries  which  are 
continually  being  started,  the  normal  growth  of  the 
manufacturing  establishments  already  operating  will 
provide  large  increases  in  load.  This  is  especially  true 
of  those  industries  in  which  heat  treatment  of  steel  or 
other  materials  is  an  es.sential  part,  as  the  use  of  elec- 
tric furnaces  and  electric  ovens  in  a  wide  variety  of 
forms  is  increasing  at  a  phenomenal  rate. 

The  coal  mining  industry  is  an  important  power 
user  in  the  Pittsburgh  district.  Notwithstanding  the 
fact  that  the  coal  companies  have  fuel  immediately 
available,  the  power  companies  are  becoming  quite 
successful  in  arranging  to  suppl)^  their  service.  Thus 
the  coal  mine  load  is  one  of  the  large  items  in  the  list 
of  industries  which  the  power  companies  serve. 

The  Government  investigation  revealed  that  the 
load  of  the  various  power  systems  in  the  Pittsburgh 
district  has  been  increasing  at  the  average  annual  rate 
of  13  to  15  percent  compounded  annually  or,  in  other 
words,  it  doubles  every  five  years.  As  a  part  of  the 
government  power  survey  an  estimate  was  also  pre- 
pared as  to  the  probable  power  requirements  of  the  dis- 
trict for  the  year  1926.  This  indicates  a  probable  need 
for  generating  capacity  around  one  and  one-half  million 
kilowatts,  without  including  steel  mills  or  the  possible 
electrification  of  existing  steam  railroads.  Govern- 
ment estimates  show  that  steam  railroad  electrification 
for  the  district  would  involve  the  installation  of  at  least 
500000  kilowatts  in  generating  capacity.  As  to  the 
sieel   mill   load,   this   is  a   matter  that   will   have   to  be 


worked  out  with  time  and  is  complicated  by  the 
general  use  of  25  cycle  equipment  in  most  of  the  mills. 
There  is  an  increasing  tendency  to  make  use  of  central 
station  service  and  undoubtedly  a  large  load  will  ulti- 
mately accrue  to  the  utilities  from  this  source. 

While  the  Pittsburgh  district  is  blessed  with  im- 
mense coal  fields,  there  are  also  a  number  of  water 
power  resources,  some  of  which  have  already  been  in- 
vestigated. It  is  to  be  hoped  that,  as  a  means  of  coal 
conservation,  some  feasible  method  can  be  worked  out 
for  the  development  of  all  commercially  practicable 
v/ater  powers.  Naturally,  in  a  commercial  corporation, 
pure  economics  control  and  it  is  hardly  reasonable  to 
expect  power  companies  to  develop  water  powers  unless 
such  developments  show  a  possibility  of  a  cost  of  opera- 
tion, including  interest  on  the  investment  in  dam,  power 
plant  and  transmission  line,  on  at  least  an  approximate 
parity  with  the  cost  of  generating  power  from  coal. 
This  subject  is  discussed  in  detail  in  this  issue  by  Mr. 
Mead.  Of  course,  from  the  national  conservation 
standpoint,  water  power  development  is  of  primary  im- 
portance and  the  study  of  some  means  of  securing  such 
development  as  promptly  as  possible  should  command 
the  attention  of  our  leading  legislators  and  public 
spirited  citizens,  as  ever)-  year's  delay  means  fui'ther 
depletion  of  a  non-renewable  coal  supply.  Certainly 
some  broad-gage  national  plan  should  be  formulated  by 
which  this  whole  problem  can  be  thoroughly  studied 
and  developed  into  a  workable  basis  of  action  which 
will  result  in  true  conservation. 

An  80- Mile  Central  Station  Bus 

C.  S.  COOK 

General  Manager, 
niu|uesne  Light  Company 

IN  THE  Colfax  station  of  the  Duque.sne  Light  Com- 
])any  three  cardinal  points  of  station  design  have 
been  kept  clo.sely  in  mind — simplicit)',  economy  and 
leliability  The  greatest  of  the  three  is,  of  cour.se,  re- 
liability for  on  that  characteristic  depends  to  the  maxi- 
mum extent  the  Company's  ability  to  obtain  and  hold 
load  from  the  power  users  and  industries  in  the  district. 
Reliability  is,  of  course,  very  closely  allied  to  simplicity 
as,  in  general,  the  simpler  any  mechanical  or  engineer- 
ing development  the  more  certain  and  reliable  is  its  op- 
eration. 

In  economy  it  is  necessary  to  consider  both  the 
economy  of  operation— fuel,  labor  and  incidental  sup- 
plies, and  also  the  economy  of  investment  costs— over- 
head, to  the  end  that  the  sum  of  the  two  may  be  a 
minimum,  as  overhead  cost  is  no  less  real  than  the  di- 
rect cost  of  operation. 

This  power  house  is  extremely  fortunate  in  its  loca- 
tion. It  is  truly  a  "mouth-of-the-mine"  plant  of  the 
type  we  have  heard  so  much  about  and  seen  so  little. 
The  prime  requisite  of  such  a  power  plant  is  water,  and 
there  are  but  few  localities  outside  of  the  Pittsburgh 
district  where  a  large  power  plant  can  he  located  at  the 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


167 


mouUi  of  a  mine  and,  at  the  same  time,  011  the  bank  of  a 
L'rge  body  of  water  such  as  a  hike  or  a  river  adequate 
to  supply  the  coohng  medium  for  a  station  capacity  of 
300  000  kilowatts  or  more. 

The  bringing  of  this  power  to  the  industries  in  the 
Pittsburgh  district  has  been  worked  out  in  a  way  mak- 
ing for  the  maximum  of  reliability.  Practically  a 
66  000  volt  bus  system  surrounds  the  entire  district,  sec- 
tionalized  as  though  it  were  employed  in  the  standard 
central  station  of  modern  design.  Eventually,  and  with 
the  installation  of  additional  units,  this  plan  will  be 
more  apparent  than  it  is  at  the  present  time,  as  the  dif- 
ferent units  in  the  Colfax  power  plant  will  feed  into  this 
66000  volt  bus  system  in  different  sections,  connection 
being  made  in  the  high-tension  substations  located  along 
this  bus  or,  as  it  has  been  tei'med,  "ring  feed".  This 
method  goes  still  further  to  ensure  service,  as  it  pro- 
tects the  system  as  a  whole  against  the  terrific  effects 
of  short-circuits  that  might  exist  were  a  plant  of  the 
contemplated  eventual  size  of  this  installation  operated 
directly  in  parallel  in  the  power  house  and  through  the 
regular  power  house  switching  gear.  22000  volt 
through  connections  with  appropriate  relays  will  also 
be  used  between  various  of  the  substations  on  this  main 
line,  which  further  tends  to  ensure  continuity  of  service 
for  the  industries  supplied  therefrom. 

The  ring  feed  S3'stem  of  itself  is  to  a  large  measure 
an  actual  demonstration  of  the  super  power  idea.  Ar- 
rangements have  already  been  made  with  various  other 
utilities  around  the  Pittsbui'gh  district  for  interconnec- 
tion with  this  ring  feed  for  the  interchange  of  energy 
and  mutual  support  in  the  service  of  the  interconnected 
companies,  and  it  is  only  a  question  of  time  until  still 
further  interconnections  will  be  made. 

It  requires  no  great  stretch  of  the  imagination  to 
foresee  the  day  when  such  interconnection  between 
r.djacent  utilities  will  become  general  and  the  industrial 
sections  of  the  countiy  covered  with  an  interconnected 
high-tension  distributing  system  which  will  furnish  an 
abundance  of  reliable  and  cheap  povi^er  to  the  industries 
requiring  it.  The  economic  value  of  such  a  system  is 
rr.anifest  further  in  that  it  will  render  available,  for  in- 
dustrial and  manufacturing  purposes,  sections  where 
today  the  want  of  adequate  water  supply  for  power  pur- 
poses or  where  the  want  of  a  readily  obtainable  fuel 
supply  makes  such  industries  impossible. 


The  Central  Station  Company  as  a 
Community  Asset 

A.  M.  LYNN 

President. 
West  Peiin  Power  Company 

IN    THIS  issue  of  the  Journal  are  two  groups  of 
articles  describing  the   central   station   power  ser- 
vice supply  of  the  Pittsburgh  district.     The  trans- 
mission lines  as  shown  on  the  maps  accompanying  these 
articles  afford  a  density  picture  of  the  industrial  de- 
velopment of  the  territory  supplied.     In  other  words, 


v.'here  the  lines  and  substations  appear  in  greatest 
number,  there  also  will  be  found  the  largest  number  of 
factories,  mines  and  industrial  operations. 

During  the  past  twenty  years  the  central  station 
has  definitely  placed  itself  in  the  economic  life  of  our 
mdustrial  centers.  It  has  taken  a  part  of  that  time  for 
tlie  central  station  company  to  reach  that  degree  of  effi- 
ciency which  places  it  among  the  determining  factors 
of  industrial  life  and  growth.  It  can  now  be  safely 
slated  that  the  central  station  has  caught  up  with  in- 
dustrial activity  and,  at  least  in  the  Pittsburgh  district, 
power  lines  are  to  be  found  wherever  there  is  any 
marked  industrial  activity. 

In  point  of  availability  of  service  the  developed 
area  is  approaching  the  point  of  saturation.  From  now 
en  the  central  station  will  be  one  of  the  major  agencies 
for  new  developments.  This  applies  not  only  in  the 
working  out  of  new  processes,  but  in  the  location  and. 
settlement  of  new  factory  sites  and  locations  of  towns 
and  cities.  The  ability  to  deliver  power  across  great 
expanses  of  country  without  regard  to  topographical 
conditions  has  opened  up  areas  which  heretofore  have 
been  suitable  for  agricultural  purposes  only,  and  some- 
times not  even  suited  for  farming.  Today  the  factory 
location  may  be  determined  by  available  transportation 
facilities,  electric  supply,  and  proximity  of  raw  products 
?nd  markets  for  the  finished  product.  The  great  prob- 
lems heretofore  attendant  upon  the  production  of  power 
have  been  eliminated  and  the  manufacturing  plant, 
v.'hich  had  to  consider  fuel  and  water  supplies  and  ash 
disposal  in  picking  its  location,  may  now  be  moved  to 
the  heart  of  the  city  or  to  the  site  in  the  open  country 
best  adapted  for  the  construction  of  the  factory  and  the 
homes  of  the  workers. 

Community  bodies,  such  as  Chambers  of  Com- 
merce and  Boards  of  Trade,  are  just  commencing  to 
realize  the  value  of  power  service  in  advertising  their 
cities  and  towns.  It  will  not  be  long  before  the  claim 
to  an  adequate  power  supply  will  supersede  the  claims 
cf  transportation,  climatic  conditions,  pure  water  and 
beautiful  scenery,  which  have  heretofore  been  featured 
in  the  prospectus  sent  out  to  attract  manufacturers  to 
the  community. 

From  the  community  point  of  view  this  carries  a 
responsibility  as  well  as  an  advantage.  The  product  of 
the  central  station  is  entirely  for  home  consumption.  It 
cannot  pack  its  kilowatt-hours  and  ship  them  outside  of 
the  territory  it  serves.  It  is  reasonable  to  expect,  there- 
fore, that  the  financing  of  the  central  station  company 
must,  in  increasing  measure,  be  provided  for  by  its 
]<atrons  and  those  interested  in  the  growth  of  the  district 
in  which  it  is  located.  The  response  to  this  need  is 
being  experienced  by  central  stations  in  all  parts  of  the 
country  and  a  comparison  of  the  number  of  local  share- 
holders from  year  to  year  will  reflect  the  appreciation 
on  the  part  of  the  local  public  of  the  value  of  the  central 
^tation. 

During  the  past  two  years  there  have  been  a  num- 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  Xo.  5 


ber  of  outlying  towns  in  the  territory  of  the  West  Penn 
Power  Company  which  have  entirely  financed  the  con- 
struction of  power  lines  into  their  communities,  the  sub- 
scription to  the  necessary  securities  being  handled  by 
the  local  bankers,  leading  merchants  and  public  spirited 
citizens.  In  most  cases  those  who  have  been  most 
active  in  this  work,  taking  securities  themselves  and 
sohciting  the  purchase  on  the  part  of  others  in  the 
town,  have  not  been  manufacturers  or  prospective 
power  users,  but  the  work  has  been  done  as  a  far-seeing 
public-spirited  movement  for  the  development  of  the 
community,  with  the  sure  knowledge  that  the  availa- 
bility of  the  power  supply  will  result  in  the  growth  of 
the  town  and  resultant  gain  to  all  of  the  business  in- 
terests therein.  The  outcome  of  this  action  has  not 
caused  regret  on  the  part  of  the  local  people  who  have 
interested  themselves  in  it. 

The  desirability  and  economy  of  central  station 
service  need  no  longer  be  preached  with  the  insistence 
which  has  been  necessary  heretofore,  but  the  true  value 
of  this  service  as  an  asset  to  the  community  may  not 
always  be  realized  and  the  central  station  interests,  in 
emphasizing  this  feature,  will  be  performing  a  service 
not  only  to  themselves  but  to  the  welfare  of  the  com- 
munities. A  good  text  for  publicity  work  may,  there- 
fore, be;  "Central  Station  Service — a  Community 
Asset". 


Now  for  the  N.  E.  L.  A.  Convention 

E.  H.  SNIFFIN 

Manager,  Power  Dept., 
Westinghouse  Electric  &  Mfg.  Co., 

THE  Convention  meets  again.  Old  friends  fore- 
gather with  the  mutual  respect  and  high  spirit 
of  men  who  have  done  big  things.  Most  of  the 
faces  are  familiar,  with  a  new  one  here  and  there  that 
we  gladly  welcome,  for  this  virile  industry  invites  new 
blood  and  new  strength  to  help  with  the  work  that  lies 
ahead. 

An  animated  scene,  this  gathering  of  N.  E.  L.  A. 
men.  Walk  among  them  and  the  striking  impression 
is  one  of  vitality  and  purpose.  Strong,  work-lined 
faces,  set  to  earnest  thinking,  but  breaking  easily  to 
hearty  laughter  until  you  wonder  which  they  enjoy  the 
more,  work  or  fun.  For  we  all  know  that  a  man's 
happiness  is  not  measured  by  his  smile,  and  it  is  in  the 
genius  of  American  business  that  we  take  our  fun  as 
we  go  along,  even  out  of  the  business  itself.  The  blue- 
bird is  not  found  in  the  pleasure  resorts.  He  perches 
right  where  we  live  and  work  and  do  things  and  serve. 
Our  Puritan  fathers  made  of  their  work  an  article  of 
religious  faith  and  a  stern  duty  with  no  attributes  of 
fun  or  enjoyment.  That  was  a  necessary  condition  of 
clearing  the  land,  fighting  the  Indians  and  establishing 


civilization.  We  still  hold  to  their  conception  of  work 
and  service  as  a  duty,  as  the  basis  of  our  National  life, 
and  as  an  honorable  requirement  of  all  men,  but  we 
have  learned  how  to  enjoy  it  and  to  put  some  humor 
into  it.  And  we  are  gradually  learning  how  to  play 
a  little  and  keep  our  minds  and  bodies  in  efficient  con- 
dition so  that  each  of  us  may  produce  the  maximum 
results  in  a  life-time.  We  are  accused  by  the  older 
countries  of  a  rawness  which  they  do  not  relish,  of  be- 
ing below  their  standards  of  culture  in  literature,  in 
art,  in  philosophy,  in  our  general  outlook  upon  life. 
Perhaps  that  is  true,  but  their  culture  has  not  spared 
them  from  their  present  social  and  economic  upheaval 
and  it  has  not  given  to  their  national  morality  very 
much  that  we  would  aspire  to.  We  all  covet  educa- 
tion. In  an  elementary  way  we  are  spreading  it  more 
generally  than  is  any  other  country.  And  it  is  a  fine 
thing  to  be  highly  educated,  widely  versed  in  literature, 
art,  history,  to  know  how  people  of  all  ages  have  lived 
and  thought;  to  be  familiar  with  the  conditions,  causes 
and  results  that  have  influenced  all  human  affairs.  .  It 
would  be  better  if  some  of  our  ills  were  removed  by  a 
sound  philosophy  rather  than  attempt  it  by  legislation. 

But  we  don't  want  the  culture  that  breeds  caste 
and  indolence,  that  puts  the  stamp  of  privilege  or  re- 
straint upon  any  birth.  We  don't  want  the  culture  that 
takes  the  place  of  performance,  that  flaunts  the  pro- 
fession of  gentleman.  We  say  of  education  that  it 
obligates  the  man  who  gets  it,  to  use  it,  and  we  think 
of  culture  as  a  refinement  of  mind  that  expands  our 
interest  and  curiosity  into  new  fields  of  enjoyment  and 
probably  of  usefulness.  Solomon  said  "In  much  wis- 
dom is  much  grief,  and  he  that  increaseth  knowledge 
increaseth  sorrow".  That  was  the  lament  of  an  old 
man  satiated  with  the  pleasures  of  life  whose 
philosophy  was  wrong  because  he  failed  to  use  his  rare 
gifts.  Most  of  his  wisdom  was  written  down  after 
he  had  been  a  fool.     He  admits  it. 

Let  culture  come  to  us,  slowly,  if  need  be,  and  it 
will  come  in  its  good  time.  W'e  have  not  had  much 
t'me  for  .the  humanities,  for  contemplation  and  polite 
thought.  There  has  been  too  much  work  to  do.  But 
\-.hile  sometimes  conscious  of  our  narrow  limits,  let  us 
not  forget  that  we  have  built  up  a  Nation,  that  we  have 
enriched  the  world  with  our  inventions,  our  enterprise 
and  our  toil,  that  we  stand  before  the  world  today  as 
the  only  great  Nation  whose  ideals  are  scoffed  at  in  the 
Courts  of  sophistication  and  culture,  but  which  are 
emblazoned  across  the  skies  where  all  weak  Nations 
look  up  to  the  stars.  In  our  Puritan  atmosphere  may 
still  be  many  faults,  but  we  have  reared  successive  gen- 
erations of  men  who  have  stamped  upon  our  national 
character  the  gospel  of  industry,  which  in  turn  has 
been  the  pabulum  of  a  high  public  morality.  Let  our 
culture  grow  in  that  good  soil. 


'^'>^. 


THE  West  Penn  Power  Company  and  affiliated 
companies  have  charters  for  approximately  4800 
square  miles  of  territory  in  Southwestern 
Pennsylvania  and  200  square  miles  in  the  Pan- 
handle District  of  West  Virginia.  This  territory  has  an 
extreme  width,  east  and  west,  of  75  miles  and  an  ex- 
treme length,  north  and  south,  of  100  miles.     Approxi- 


GEO.  S.  HUMPHREY" 

Electrical  Engineer, 
West  Penn  Power  Company 

Donald  and  Bridgevi 
made     at     Windsor 


c  substations.  Connection  is  also 
and  East  Liverpool  with  the 
system  of  the  American  Gas  &  Electric  Company,  which 
in  turn  is  interconnected  with  the  Akron  properties  of 
the  Northern  Ohio  Traction  &  Light  Company.  It  has 
been  found  that  the  interconnection  of  the  transmission 
lines  of  the  various  companies  has  been  of  considerable 


mately  one-half  of  this  territory  is  thoroughly  covered     mutual  benefit,  especially  in  cases  of  emergency. 


by  transmission  lines,  so  that  any  new  load  may  be 
reached  by  constructing  only  a  comparatively  short  line. 
Lines  are  being  extended  into  sections  which  are  not 
now  served,  as  rapidly  as  required  by  industrial  develop- 
ments. The  load  center  is  4.5  miles  west  and  slightly 
north  of  Elizabeth,  Pa. 


FIG.    I — POWER  GENERATI.NO   AXn  TRANSMISSION   SYSTEMS   IN   WEST- 
ERN  PENNSYLVANIA  AND  EASTERN  OHIO 

The  load  is  distributed  over  a  network  of  lines, 
which,  on  December  31,  1920,  contained  855  miles  of 
25  000  volt  circuit,  from  which  power  is  taken  through 
180  substations,  which  reduce  the  voltage  from  25  000  to 
6600  or  2300  volts  for  use  by  a  single  customer,  or  for 
further  distribution  at  lower  voltages,  as  may  be  re- 
quired. The  25  000  volt  network  receives  power  at  four 
main  points : — 

I — Connellsville  Power  Station 
2— Springdaie  Power  Station 
3 — Windsor  Power  Station 
4 — Washington    Substation 

There  are  in  addition  seven  small  power  stations 
which  may  feed  power  into  the  net-work,  and  which  are 
used  when,  for  any  reason,  the  other  stations  are  unable 
to  carry  the  load.     This  network  is  also  connected  to 

interchange  power  with  the  Duquesne  Light  Company  this  plant  is  indoors  and  each  "of  the  main  generating 
£.t  nine  dififerent  points,  the  principal  ones  being  the  units  has  its  own  bank  of  transformers,  which  are 
Cheswick,    Elizabeth,     Washington,    Canonsburg,    Mc-      paralleled  only  on  the  high-tension   side.     The  25000 


All  of  the  transmission  lines  at  present  are  operated 
at  25  000  volts  except  the  steel  tower  line  from  Windsor 
power  station  to  Washington  substation  which  is  built 
and  insulated  to  operate  at  132  000  volts,  but  has  thus 
far  been  operated  at  66000  volts.  There  is  another 
steel  tower  line,  constructed  and  insulated  to  operate  at 
132000  volts,  from  the 
Springdale  power  station  to 
Crows  Nest  substation,  but 
this  line  is  at  present  oper- 
ated at  25  000  volts.  Until 
1 917,  when  the  Windsor- 
Washington  66000  volt  line 
was  put  in  service,  the  en- 
tire load,  then  amounting  to 
60000  kilowatts,  was  trans- 
mitted at  25  000  volts,  and  a 
comparatively  large  amount 
of  power  is  still  trans- 
mitted at  this  voltage.  It  is 
possible  to  give  satisfac- 
tory service  with  this  voltage, 
since  the  load  is  transmitted 
from  power  stations  in 
several  different  directions, 
good  power-factor  is  maintained  by  the  use  of  syn- 
chronous apparatus,  and  automatic  induction  voltage 
regulators  are  used  on  all  lighting  circuits  and  most  im- 
portant power  circuits.  It  has  been  the  practice  to 
build  25  000  volt  lines  rather  than  higher  voltage  lines 
wherever  practicable,  since  load  may  be  taken  more 
economically  from  the  lower  voltage  lines.  It  is  in- 
tended to  raise  the  voltage  on  the  existing  steel  tower 
lines,  and  to  extend  the  132  000  volt  lines  as  may  be 
necessary  to  supply  additional  service  as  required. 
The  probable  location  for  such  lines  is  shown  in  Fig. 
2,  although  future  industrial  developments  may  make 
advisable  some  changes  in  these  plans. 

The  oldest  of  the  three  main  generating  stations  is 
at  Connellsville.     All  of  the  25  000  volt  apparatus   at 


Volt  Linti 
Volt  Lines 
)  Volt  Lints 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


■     11  f-^ii^H  rirrnit  breakers  are  mounted     ing  bv  electrolytic  lightning  arresters  and   choke   coils, 

volt  electncal ly  cont.oUed  cuout  b.eakers^^^    ^^^    ^^^^     ^.^^^  ^^^  ^^^  ^^^^^  ^^  transformers  having  a  total  ca- 

l^ed  teens      Each  line  is  protected  against  lightn-      pacity  of  6i  500  k-v-a,  which  raise  the  voltage  from  2300 


Proposed   Hvdro    Plant 
FIG.  2-TRANSMISSION  SYSTEM  OF  THE  WEST  PENN  POWER  COMPANY 


May,  192 1 


THE  ELECTRIC  JOURXAL 


volts  delta  to  25  000  volts  delta  for  three  7500  kv-a 
banks,  and  to  25  000  volts  star  with  neutral  grounded 
through  resistance  for  two  19  500  kv-a  banks. 

At  Windsor,  the  next  station  put  in  service,  all  of 
the   high-tension   ei|uipment,   both    132000   and   25000 


KIC.   3 — DEAD-EXI)  TOWER  ON  THE   SI'RINCDAI.E-CROWS   NEST 
TRANSMISSION  LINE 

This  line  is  insulated  for  132  000  volts  but  is  now  operated  at 
25  000  volts.  It  carries  two  No.  4/0  copper  transmission  circuits, 
two  y^  in.  copper  clad  overhead  ground  wires  and  two  No.  8 
phono-electric  telephone  wires.  The  line  is  graded  to  allow  the 
addition  of  one  25  000  volt  circuit. 

volts,  is  outdoors.  There  is  a  bank  of  three  10  000  kv-a 
transformers,  with  a  fourth  as  spare,  which  steps  up  the 
generator  voltage  from  11  000  volts  delta  to  66000  volts 
star,  with  neutral  grounded  without  resistance.  The 
transformers  are  protected  by  circuit  breakers,  elec- 
trolytic lightning  arresters  and  choke  coils.  All  of  the 
apparatus  is  built  to  operate  at  132000  volts  although 
now  used  at  66  000  volts.  There  is  at  present  a  bank  of 
three  3500  kv-a  transform.ers  which  step  up  from  gener- 
ator voltage  II  000  delta  to  25  000  delta.  A  new  bank 
consisting  of  three  6667  kv-a  transformers,  with  a  spare, 
is  being  installed  to  supply  the  23  000  volt  lines  in  paral- 
lel with  the  present  bank  of  transformers.  The  new 
bank  will  be  connected  star  on  both  sides  and  have  a 
tertiary  delta-connected  winding  to  hold  the  neutral 
point  stable  and  supply  some  2300  volt  service.  The 
star  connection  is  being  used  so  that  the  25  000  volt  neu- 
tral may  be  grounded  as  at  the  other  generating  sta- 
tions. Since  the  existing  bank  is  connected  delta  on 
both  sides  the  new  bank  must  be  connected  star  on  both 
sides  so  that  the  two  banks  may  operate  in  parallel.  The 
Windsor  station  .will  then  have  a  capacity  of  30000 
kv-a  at  66  000  volts  and  30  500  kv-a  at  25  000  volts.  At 
present  three  25  000  volt  lines  are  supplied   from  this 


station  and  two  more  will  be  added  in  the  near  future. 
Lightning  protection  consists  of  electrolytic  arresters 
and  choke  coils  on  each  circuit. 

At  the  Springdale  power  station,  which  was  put  in 
service  in  1920,  there  are  two  banks  of  transformers, 
each  consisting  of  three  8333  kv-a  transformers,  with  a 
seventh  as  spare,  which  supply  the  25  000  volt  network. 
These  transformers  are  connected  11  000  volts  delta  to 
25  000  volts  star  with  neutral  grounded  through  resist- 
ance. The  transformers  are  installed  outdoors  and  the 
electrolytic  lightning  arresters  are  placed  on  the  turbine 
room  roof.  The  rest  of  the  25  000  volt  equipment,  in- 
cluding busses,  circuit  breakers,  instrument  trans- 
formers, etc.,  is  placed  in  doors.  It  was  originally  in- 
tended to  place  all  high-tension  equipment  outdoors  on 
:cn  elevated  concrete  platform.  This  platform  would 
have  to  be  about  twenty  feet  above  ground  level  to  be 
out  of  reach  of  floods  and  be  supported  on  piles  driven 
15  feet  to  gravel.'  Since  there  was  space  on  the  main 
switch  floor  which  could  be  used,  it  was  decided  to  place 
the  25  000  volt  switches  and  bus  in  doors. 

The  top  conductors  of  the  four  circuits  crossing  the 
Allegheny  River  must  be  supported  at  a  distance  of  175 
feet  above  the  ground,  and  since  the  building  columns 


FIG.    4 — TRANSPOSITION    TOWER   ON   THE   WINDSOR-WASHINGTON 
TRANSMISSION  LINE 

Showing  a  standard  tower  in  the  distance.  This  particular 
tower  is  located  on  a  short  section  of  the  line  where,  to  secure 
the  right  of  way.  it  was  necessary  to  install  at  the  beginning  all 
the  conductors  that  would  ever  be  placed  on  the  tower.  A  special 
long  cross-arm  is  provided  to  facilitate  making  the  transposition. 
To  avoid  excess  grading  on  hillsides,  extensions  in  imiltiple 
of  2.5  ft.  arc  added  to  the  base  of  the  standard  tower. 

have  ample  strength  to  support  these  circuits,  the  sup- 
porting tower  for  the  river  crossing  and  the  lightning  ar- 
I  esters  are  placed  on  the  roof.  A  considerable  saving  in 


172 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


structural  steel  as  well  as  in  concrete  was  thus  realized 
by  placing  most  of  the  high-tension  equipment  in  the 
building  and  on  the  roof.  Since  there  was  room  in  the 
building  to  give  the  equipment  and  conductors  practic- 
ally the  same  spacing  they  would  have  had  outdoors,  and 
in  addition  to  install  barriers,  it  was  considered  that  the 
reliability  would  be  considerably  greater  indoors  than 
outdoors.  The  25  000  volt  busses  are  arranged  vertically 
in  concrete  cells.  Each  25  000  volt  circuit  breaker  is 
mounted  in  a  separate  room  10  by  12  by  25  feet  high, 
and  is  electrically  operated.  Each  25  000  volt  line  is 
equipped  with  a  grounding  device,  consisting  of  three 
knife  switches  mounted  on  top  of  the  bus  structure  and 
controlled  from  a  single  handle  mounted  in  the  corre- 
sponding switch-room.  The  grounding  device  is  elec- 
trically locked  in  the  open  position,  when  the  line  is 
alive,  by  means  of  current  supplied  by  a  25  000  volt  po- 
tential transformer  connected  on  the  line  side  of  the  cir- 
cuit breaker.  When  the  handle  is  in  the  closed  position, 
it  opens  the  closing  circuit  for  the  corresponding  circuit 
breaker.  Thus  it  is  impossible  to  ground  the  line  unless 
the  circuit  breaker  is  open,  and  it  is  impossible  to  close 
the  circuit  breaker  when  the  line  is  grounded.  Spring- 
dale  can  thus  supply  50  000  kv-a  to  the  25  000  volt  lines. 
It  is  probable  that  this  is  all  of  the  power  that  can  eco- 
nomically be  transmitted  from  the  station  at  this  voltage 
and  that  the  power  from  future  units  will  be  transmitted 
at  66  000  or  132  000  volts. 

The  Washington  substation  contains  two  trans- 
former banks,  each  with  three  5000  kv-a  transformers, 
with  a  seventh  unit  as  spare,  which  reduce  the  voltage 
from  66  000  delta  to  25  000  star,  with  neutral  grounded 
through  resistance.  All  of  the  132  000  volt  apparatus  is 
installed  out  doors  and  the  apparatus  and  installation 
are  practically  duplicates  of  the  similar  installation  at 
Windsor.  The  25  000  volt  apparatus  is  installed  in- 
doors, as  there  was  available  a  brick  building  in  good 
condition  which  had  been  used  as  a  steam  plant.  The 
25  000  volt  circuit  breakers  are  mounted  in  cells  and 
each  line  is  protected  by  low  equivalent  lightning 
arresters. 

The  Windsor-Washington  steel  tower  line  is  26 
miles  long  and  carries  one  circuit  of  4/0  stranded 
copper  wire,  two  y%  in.  galvanized  steel  overhead 
ground  wires  and  two  No.  8  phono-electric  telephone 
wires.  Space  is  provided  for  an  additional  132  000  volt 
circuit  and  a  25  000  volt  circuit  may  also  be  added. 
There  are  four  types  of  tower  on  this  line,  each  of 
which  is  used  in  two  standard  heights;  a  40  ft.  tower, 
which  carries  the  lowest  132  000  volt  conductor  at  a  dis- 
tance of  40  ft.  above  ground,  and  is  76  ft.  9  in.  high, 
and  a  50  ft.  tower  which  is  86  ft.  9  in.  high  and  gives  a 
minimum  wire  distance  of  50  ft.  above  ground.  The 
weights  of  the  towers  are  as  follows : — 


Type 
S-i 

S-2 

A- 1 
D-E 


Used  For 

Suspension 
Suspension 

.\ngle 
Dead  End 


Weight  of  Tower 
40  Ft.  50  Ft. 

7600  lb.  8500  lb. 
loioo  lb.  1 1200  lb. 
10700  lb.  I 1800  lb. 
10900    lb.  12000    lb. 


The  S-i  tower  is  used  only  on  straight  line  sections 
where  spans  are  not  over  550  feet  and  the  S-2  tower  on 
straight  line  sections  for  spans  between  550  and  800  ft. 
The  A-i  type  is  used  at  points  where  there  is  a  hori- 
zontal angle  or  where  the  spans  are  more  than  800  ft. 
The  D-E  tower  is  used  wherever  wires  are  attached  by 
strain  insulators.  The  longest  span  on  this  line  is  1 1  !;o 
ft.,  the  shortest  is  265  ft.  and  the  average  is  564  ft.  The 
footings  for  all  types  of  tower  consist  of  angles  set  in 
concrete  to  a  depth  of  7  to  8  ft.  in  the  ground.  On  hill- 
sides, extensions  in  multiples  of  2.5  ft.  are  added  to  the 
base  of  the  tower  on  one,  two  or  three  legs  as  required 
to  avoid  excessive  grading.  The  tower  proper  is  con- 
nected to  the  footing  angles  by  means  of  an  angle  about 
2.5  ft.  in  length,  which  is  half  imbedded  in  the  concrete 
footing  where  the  steel  leaves  the  concrete.  This  short 
piece  should  show  the  most  rapid  deterioration  and  can 
be  replaced  without  interrupting  service  or  injuring  the 
tower.  Insulators  of  the  suspension  disk  type  are  used, 
eleven  in  series  at  suspension  points  and  two  strings  of 
twelve  disks  each  in  parallel  at  strain  points.  Each  tele- 
phone wire  is  supported  on  two  25  000  volt  pin  insula- 
tors at  each  tower  and  is  transposed  at  each  tower. 
The  power  circuit  has  two  transpositions  which  divide 
the  entire  length  into  three  equal  portions.  The  hori- 
zontal spacing  between  conductors  is  29  ft.  on  the 
middle  crossarm,  and  22  ft.  on  the  top  and  bottom  arms. 
The  vertical  distance  between  crossarms  is  13  ft.  Since 
this  line  will  transmit  satisfactorily  at  66000  volts,  all 
the  power  that  will  be  needed  from  Windsor  to  Wash- 
ington until  additional  units  are  installed  at  Windsor, 
or  until  the  132  000  volt  lines  are  extended  beyond 
Washington,  it  has  been  operated  at  66  000  volts  with 
insulation  for  132  000  volts.  In  the  four  years  this  line 
has  been  in  service  it  has  had  but  two  interruptions,  both 
from  external  causes. 

The  steel  tower  line  from  Springdale  to  Crows 
Nest  has  towers  which  are  duplicates  of  those  on  the 
Windsor-Washington  line.  However,  the  Springdale- 
Crows  Nest  line  carries  two  No.  4/0  copper  circuits  in- 
sulated for  132  000  volts,  but  now  operated  at  25  000 
volts;  two  y^  inch  40  percent  conductivity  copper-clad 
overhead  ground  wires,  and  two  No.  8  phono-electric 
telephone  wires.  On  this  line  nine  Jeffrey  Dewitt 
disks  are  used  at  suspension  points  and  two  strings  of 
ten  disks  each  in  parallel  at  strain  points.  The  longest 
span  on  this  line  is  1450  ft.  where  it  crosses  the  Alle- 
gheny River  at  Springdale,  one  end  of  this  span  being 
supported  on  a  75  ft.  tower  on  top  of  the  turbine  room 
r.nd  the  other  end  on  a  twin  tower  145  ft.  high.  The 
longest  span,  using  standard  towers,  is  1288  ft.,  the 
shortest  span  is  250  ft.  and  the  average  is  625  ft.  This 
line  was  completed  in  September,  1920. 

The  25  000  volt  lines  form  a  rather  complicated 
network,  containing  many  loops  and  cross-connections, 
so  that  it  is  possible  to  supply  most  consumers  from 
more  than  one  direction.  There  are  approximately  560 
miles  of  25  000  volt  wood  pole  line  of  which  250  mites 


May,   i<)2i 


THE  HLF.CTRIC  JOURNAL 


173 


is  double  circuit  and  short  sections  in  congested  districts 
carry  as  man}-  as  tour  circuits.  Standard  construction 
uses  35  ft.  chestnut  poles  with  an  average  spacing  of 
132  ft.,  locust  pins,  Douglas  tir  cross-arms  and  braces, 
and  steel  channel  extensions  with  insulating  spool  for 
supporting  the  overhead  ground  wire.     Pin  type  insula- 


KIG.    5 — .\  TYPIC.M.    MEDIUM    CAP.\CnY   25   OOO  VOI.T   SUr.ST.MION 

With  25  000  volt  apparatus  outdoors,  and  lov.-tensiou 
switches,  induction  regulators  and  other  apparatus  located  in  a 
small  brick  building. 

tors  are  used  which  are  rated  at  35  000  volts  and  they, 
together  with  the  wooden  pins,  cross-arms  and  poles, 
make  very  effective  insulation  for  25  000  volt  lines. 

The  first  of  these  lines  was  built  in  1903  and  no 
overhead  ground  wires  were  used  until  1910.  At  that 
time  an  overhead  wire  was  installed  on  a  few  sections 
of  line  to  determine  whether  or  not  the  troubles  from 
lightning  would  be  decreased.  The  improxcment  was 
so  apparent  that  ground  wires  have  been  added  to 
rdl  25  000  v(jlt  lines  and  have  for  several  j'ears  been 
standard  construction.  The  ground  wire  was  added  tn 
existing  lines  by  supporting  it  on  angle  extensions  bolted 
to  the  tops  of  the  poles.  The  first  overhead  wires  in- 
stalled were  clamped  directly  to  the  supports,  but  from 
an  exjieriment  made  on  a  section  with  ground  wire  in- 
sulated, it  was  thought  to  be  of  some  benefit  to  have  a 
little  insulation  between  the  ground  wire  and  support. 
The  present  standard  practice  is  to  attach  the  ground 
wire  to  an  insulating  spool  by  means  of  tie  wire,  the 
spool  being  bolted  between  the  flanges  of  a  four  inch 
channel  which  has  the  web  cut  out  to  make  room  for 
the  spool.  This  provides  a  very  good  mechanical  con- 
nection and  eases  off  vibrations  of  the  wire  at  the  sup- 
port. No.  4  solid  copper  wire  is  used  for  overhead 
ground  wire,  and  it  is  grounded  every  fifth  |)ole.  Two 
of  the  eight  grounds  per  mile  are  made  to  F'aragon 
ground  cones  and  the  remainder  to  pipes  driven  eight 
feet  in  the  ground,  using  one  cone  or  one  pi].)e  for  each 
ground.  A  ground  is  always  installed  on  a  pole  near  a 
stream.  Most  of  the  23  000  volt  circuits  are  of  i/o 
copper  wire;  however,  a  few  of  the  main  sections  are  of 


^./o  co])per,  and  short  branch  lines  are  of  No.  4  cdppcr. 
The  spacing  between  conductors  is  3O  inches  with  the 
three  conductors  of  each  circuit,  of  a  double  circuit  line, 
in  the  form  of  an  equilateral  triangle. 

Standard  construction  is  used  for  crossings  o\er 
railroads  or  communication  circuits  except  under  un- 
usual conditions.  iV  large  part  of  the  25  ooo  volt  [Joles 
carry  low-tension  distril)ution  circuits  and  space  is  al- 
wa}s  alldwed  for  at  least  one  such  circuit.  A  private 
telei)hone  circuit  is  carried  on  all  pole  lines  except  short 
branch  lines  to  the  less  iniporiani  loads.  The  telephone 
circuit  is  of  No.  10  copjier  wire  .-utached  about  seven 
feet  below  the  25000  \n\\  C(in(huliir>  and  is  transposed 
c\er\'  five  poles. 

The  one  hundred  and  eighty  25000  volt  substa- 
tions co\er  a  wide  range,  the  largest  having  a  ca|)acity 
of  9750  k\'-a  and  the  smallest  150  kv-a.  .'^ome  of  them 
have  switching  e<iuipment  to  control  several  25  000  volt 
l.nes.  motor-generator  sets  or  rotary  converters  to 
supjjly  railwav'  or  mine  load,  synchronous  condensers 
for  voltage  control,  and  a  number  of  low  voltage  dis- 
tribution circuits  at  O600  or  2300  \oIts  or  both.  Many 
of  the  substations  are  \ery  simple,  consisting  only  of 
25000  \(jlt  lightning  arresters,  ;iir  break  switch,  fuses 
;md  transformers,  all  of  which  are  placed  out  doors. 
The  West  Penn  Railways  Conipany.  which  is  affiliated 
\  ith  the  West  Penn  Power  t"omp;niy,  operates  street 
i:\ilways  over  a  large  part  of  the  territory  served  by  the 
Power  Company,  and  it  has  been  possible  in  many  cases 
to  locate  substations  so  that  they  could  supply  the  trolley 
hues  and  also  be  used  to  control  the  25000  volt  trans- 
r.iission  lines.  There  are  at  present  32  substations 
which  have  attendants  on  duty  at  all  times.  All  of  the 
apparatus  in   these  stations,  most  of  which   were  built 


KIG.  6 — SUliSIATlON  .XT  MCDONALD,  l:\. 

The  indoor  equipment  consists  of  a  2750  la--a  synchronous 
condenser,  which  drives  a  200  k\v  generator  to  supply  a  small 
direct-current  railway  load ;  the  switches  and  protective  equip- 
ment for  five  25  000  volt  lines  and  for  one  2200  and  two  6600 
volt  circuits  with  induction  regulators.  Three  1500  kv-a  trans- 
formers are  located  outdoors.  This  is  one  of  the  points  where 
interconnection  is  made  with  the  lines  of  the  Duquesnc  Light 
Company  . 

between  1905  and  1915,  is  placed  indoors  in  two  or 
three-story  brick  buildings,  except  that  in  many  in- 
stances the  transformers  are  placed  out  doors.  Provi- 
sion has  been  made  to  "jumper  out"  each  25  000  volt 


174 


THE  ELECTRIC  JOURNAL 


Vol.  X\Iir,  No.  5 


oil  switch  so  that  it  may  be  disconnected  for  inspection 
or  repair  without  interrupting  service  on  the  Hne  which 
it  controls.  In  many  substations  provision  has  been 
made  to  synchronize  between  the  25  000  volt  lines. 
I',ach  circuit  in  each  substation  is  protected  against 
lightning  by  means  of  low  equivalent  lightning  arresters. 
There  are  288  sets  of  arresters  now  installed  on  the 
25  cx)0  lines  which  makes  an  average  of  one  set  of  ar- 
resters per  two  miles  of  pole  line.  Experience  on  the 
West  Penn  System  indicates  that  there  is  considerable 
benefit  in  bringing  a  line  conductor  straight  to  an  ar- 
rester and  then  taking  it  directly  back  on  itself  for  a 
few  feet.  This  is  referred  to  as  a  "dip".  The  lightn- 
ing seems  to  have  a  tendency  to  follow  a  straight  path 
through  the  arrester  rather  than  suddenly  reverse 
through  a  180  degrees  turn.  This  effect  may  be  noted 
especially  on  the  low-tension  arrester  shown  in  Fig.  5. 
The  wiring  to  the  arrester  is  usually  made  of  insulated 
wire  and  the  two  conductors  are  tied  together. 

Present  practice  is  to  install  25  000  volt  apparatus 
outdoors,  and  low-tension  switches,  rotating  machinery, 
regulators,  meters,  etc.,  in  a  building.  Fig.  5  shows  a 
cross-section  of  a  typical  installation  for  medium  ca- 
pacity semi-attended  stations  wliich  require  low-tension 
equipment. 

The  system  power-factor  is  approximately  90  per- 
cent as  a  result  of  the  installation  of  considerable  syn- 
chronous apparatus  in  the  Company's  own  substations, 
and  by  so  arranging  rate  schedules  as  to  encourage  cus- 
tomers to  use  synchronous  apparatus  and  to  operate  it 
at  high  or  leading  power-factor.  A  5000  kv-a  syn- 
chronous condenser  is  installed  at  Washington,  another 
at  Crows  Nest,  and  there  are  several  smaller  condensers 
scattered  over  the  system.  It  would  appear  that  it  is 
economical  to  use  condensers  rather  freely,  especially 
at  stations  where  there  are  several  circuits  which  will 
benefit  therefrom. 

The  generator  of  a  30000  kw  turbine  unit  is  now 
being  installed  in  the  Windsor  generating  station  to  be 
operated  as  a  synchronous  condenser.  The  fields  of  the 
Windsor  units  are  the  limit  to  their  capacity  and  con- 
siderable more  load  may  be  obtained  from  them  by  im- 
proving their  power-factor.  The  steam  end  of  the  new 
unit  will  be  kept  on  hand  for  emergencies. 

The  25  000  volt  lines  were  operated  with  delta-con- 
nected transformers  at  power  stations  and  with  neutral 
point  isolated  from  ground  until  1917.  By  that  time 
the  system  had  grown  to  such  an  extent  that  it  was 
thought  advisable  to  ground  the  neutral  in  order  to  de- 
crease the  damage  caused  by  local  failures,  causing  high 
voltage  surges  which  sometimes  gave  trouble  at  points 
even  remote  from  the  location  of  the  original  trouble. 
The  25  000  volt  neutral  is  now  grounded  at  Connells- 
ville,  Springdale  and  Washington.  Provision  is  also 
being  made  to  ground  it  at  the  Windsor  power  station. 
At  each  of  the  four  points  the  neutral  is,  or  will  be,  con- 
nected to  ground  through  a  resistance  of  28.8  ohms.  It 
is  thought  that  the  use  of  a  grounded  neutral  will  also 


bfc  of  considerable  benefit  in  isolating  grounded  line  sec- 
tions by  the  use  of  relays,  which  are  now  being  installed. 

The  25  000  volt  transmission  system  is  a  very  diffi- 
cult one  to  relay,  with  its  many  loops,  cross-connections 
and  substations  in  series  between  power  plants.  A  sys- 
tem of  low-voltage  relays*  has  been  used  for  a  number 
of  years,  with  automatic  circuit  breakers  which  are 
locked  so  that  they  cannot  open  unless  the  voltage  is  be- 
low some  predetennined  value  for  which  the  low-volt- 
age relay  is  set.  This  system  of  relaying  was  the  most 
satisfactory  one  available  at  the  time  it  was  installed, 
especially  for  a  system  which  is  supplied  from  one 
power  plant,  which  was  the  condition  at  that  time.  Now 
that  there  are  three  main  power  plants  and  one  66000 
volt  substation  supplying  power  to  the  25  000  volt  sys- 
tem, and  that  there  has  been  a  great  improvement  in  the 
design  and  application  of  relays,  a  change  in  the  relay 
system  is  being  made,  using  induction  type  relays 
throughout.  Inverse  time  limit  overload,  and  inverse 
tune  limit  reverse  energy  relays  are  being  installed  to 
get  protection  against  short-circuits.  Protection  against 
grounds  will  be  obtained  by  means  of  a  single  one  am- 
pere inverse  time  limit  overload  relay  for  each  circuit, 
connected  to  operate  from  the  vmbalanced  current  be- 
tween the  three  phases.  One  of  the  main  difficulties  in 
applying  this  relay  system  is  the  comparatively  small 
ground  current  that  can  flow  through  transmission  con- 
ductors and  the  resistance  connected  between  trans- 
former neutral  points  and  ground.  However,  in  view 
of  the  fact  that  current  will  be  supplied  to  ground 
at  four  different  points,  it  is  thought  that 
there  should  be  sufficient  unbalanced  current  flowing  to 
the  grounded  section  to  trip  out  the  switch  at  each  end. 
The  ground  current  will  in  nearly  all  cases  be  consider- 
ably less  than  short-circuit  current,  so  that  circuit 
breakers  will  not  trip  from  overload  in  case  of  ground, 
and  the  difference  between  time  settings  on  ground  re- 
lays for  several  substations  in  series  may  be  made  large 
enough  to  afford  positive  selection  in  case  of  grounds. 

At  generating  stations  and  main  substations,  the 
generators  and  transformers  are  protected  only  by  bal- 
anced relays,  which  will  operate  only  in  case  of  trouble 
in  the  apparatus  involved,  but  will  not  operate  on  over- 
load. Balanced  relay  protection  is  also  provided  m 
some  instances  for  house  generators  and  for  motors  of 
motor-generator  exciter  sets. 

Details  of  operating  the  power  plants  and  trans- 
mission system,  apportioning  load  between  plants,  locat- 
ing troubles,  etc.  are  supervised  by  a  system  operator, 
or  chief  load  dispatcher,  located  in  the  Pittsburgh  office, 
working  through  four  district  dispatchers,  located  at 
Springdale,  Connellsville,  Washington  and  Windsor, 
who  in  turn  supervise  the  operation  in  their  own  dis- 
tricts. 

The  chief  aim  throughout  the  years  of  development 
of  the  transmission  system  has  been  to  provide  relia- 
bility of  service.     Power  is  supplied  to  the  25  000  volt 


*Trans.  A.  I.  E.  E.  Vol.  XXXVI  p.  409- 


May,  1921 


THE  ELECTRIC  JOURNAL 


175 


iietvvork  at  four  points  well  distributed  over  the  terri- 
tory, each  being  located  near  a  district  having  large  load 
density,  and  tied  in  with  the  others  over  several  trans- 
mission circuits.  Connection  can  be  made  with  the 
l.nes  of  the  Duquesne  Light  Company  at  nine  points, 
Vv'idely  distributed  over  the  territory,  so  that  in  emer- 
gencies either  of  the  two  systems  has  the  use  of  the 
transmission  facilities  of  both.  Consumers  may  receive 
power  over  more  than  one  line,  so  that  the  failure  of  any- 
one section  will  not  cause  intern.iption  to  service,  except 
for  a  few  single  line  extensions  into  new  territory 
v/here  it  has  not  yet  been  possible  to  provide  duplicate 
service.  All  of  the  lines  are  provided  with  overhead 
ground  wires,  and  lightning  arresters  are  used  very 
liberally,  one  set  of  arresters  being  provided,  on  the 
average,  for  each  two  miles  of  pole  line.  There  are 
many  switching  points  distributed  throughout  the  trans- 
mission system  where  operators  are  kept  on  duty  at  all 
tunes.  An  extensive  system  of  relays  for  sectionalizing 
the  lines  automatically  is  provided  and  is  now  being  re- 
vised to  take  advantage  of  the  latest  developments  in 
the  art  of  applying  relays.     A  private  telephone  circuit 


is  carried  on  all  transmission  lines  so  that  it  is  possible 
to  reach  most  substations  over  more  than  one  private 
line  and  patrolmen  may  communicate  quickly  with  load 
dispatchers  from  any  point  along  the  lines.  The  terri- 
tory is  also  served  by  the  Bell  and  several  independent 
telephone  systems  whose  service  may  be  used  in 
case  communication  cannot  be  had  over  the  pri- 
vate lines.  The  distance  between  poles  is  compara- 
tively short,  and  the  pole  top  construction  is  ex- 
tremely rugged,  so  that  mechanical  line  failures  are  re-. 
duced  to  a  minimum.  The  line  insulation  is  so  high 
that  it  is  necessary  to  have  manufacturers  provide  spe- 
cial bushings  for  transformers  and  oil  switches,  in 
order  that  such  in.sulalion  will  not  be  the  weakest  part 
of  the  system. 

The  reliability  of  service,  which  may  be  obtained 
from  a  power  transmission  system  constructed  and  op- 
erated along  most  modern  lines,  has  reached  the  point 
where  the  probability  of  interruptions  has  become  so 
remote  as  to  warrant  consumers,  distant  from  power 
plants,  to  expect  service  practically  as  reliable  as  from 
plants  nearby  or  from  their  own  plants. 


^JfN'l 


1:1 


■^ 


leiioii'aajig 


G.  G.  BELL 

Manag'er,  Power  Department 
West  Penn  Power  Company, 


P©B:fa 


THE  greater  part  of  the  power  produced  by  the 
West  Penn  Power  Company  is  generated  at  three 
stations.  The  Connellsville  station  is  located  in 
the  southeast  part  of  the  territory  and  carries  the  load  in 
what  is  commonly  called  the  "Coke  Region"  of  south- 


located  on  the  Allegheny  River  above  Pittsburgh  and 
carries  the  load  in  West  Penn  territory  north  of  a  line 
drawn  east  and  west  through  the  City  of  Pittsburgh. 

The  Pittsburgh  District  is  fortunate  in  having  large 
fields  of  coal  in  proximity  to  ample  supplies  of  circulat- 


FIG.    I— CONNELLSVILLE  POWEK   STATION 

western  Pennsylvania.  Windsor  station  is  located  on  ing  water,  so  that  there  are  at  present  in  this  district, 
the  Ohio  River  and  carries  the  load  between  the  Ohio  either  in  operation  or  under  construction,  five  stations 
and   Monongahela   Rivers.     The   Springdale   station   is     each  laid  out  for  a  minimum  of  100  000  to  a  maximum 


1/6 


THE   ELECTRIC  JOURNAL 


Vol.   XVIII,  No.  5 


of  300000  k\v  ultimate  capacity,  which  will  draw  their 
coal  supply  from  mines  located  so  as  to  deliver  coal 
directly  to  the  power  house,  or  connected  to  it  by  short 
privately-owned  railways.  The  advantages  of  such  an 
arrangement  are  numerous. 

The  location  of  a  power  house  at  the  mine  mouth 
eliminates  the  danger  from  strikes  on  transportation 
systems  which  may  deplete  the  coal  storage  at  a  time 
\'  hen  it  should  be  built  up  to  take  care  of  irregularities 
i:.  the  car  supply  caused  by  the  greater  demand  in  the 
severe  winter  weather. 

Interests  affiliated  with  West  Penn  Power  Com- 
pany were  fortunate  in  securing  large  tracts  of  coal  at 
two  points  in  its  territory.  At  one  of  these,  in  the 
northern  portion  adjacent  to  the  new  Spriiigdale  sta- 
tion, the  vein  has  an  average  thickness  of  7  feet  5  inches, 
with  an  exceptionally  good  roof.  The  other  tract,  at 
Windsor,  West  X^irginia,  on  the  Ohio  River  in  the  Pan- 


passed  out  with  the  ash  and  the  greater  amount  of 
excess  air  necessary  to  burn  the  higher  ash  coal.  In  the 
case  of  the  mine  at  Windsor,  this  arrangement  will  not 
add  anything  to  the  first  cost  of  the  tipple  and  it  is  ex- 
pected that  the  cleaner  coal  obtained  will  have  a  very 
1  eneficial  effect  on  the  efficiency  of  the  station  and  the 
e;!se  with  which  it  is  operated.  When  a  station  is  sup^ 
plied  with  a  single  grade  of  coal,  the  continual  adjiisi- 
ment  of  the  stokers,  to  adapt  them  to  varying  gra<k- 
(jf  coal,  is  eliminated. 

CONNELLSVII.I.K  .STATIO.X 

The  Connellsville  station  is  located  on  the 
^'oughiogheny  River  about  35  miles  in  an  air  line  frcjm 
Pittsburgh.  This  is  the  oldest  plant  of  the  three.  The 
present  peak  capacity  is  about  60  000  kw.  There  are 
seven  turbogenerators,  the  largest  two  being  of  180CX) 
kw  capacity  each,  and  the  other  fivt  ranging  in  i;i|.;icitv 


II 


M        --:?■, 


handle  District  of  West  Virginia,  has  an  average  thick- 
ness of  4  feet  6  inches  and  supplies  coal  to  the  two 
power  houses  there  constructed  under  one  roof  and 
owned  by  the  West  Penn  Power  Company  and  the  Ohio 
Power  Company. 

Considerable  of  the  coal  mined  and  sold  on  the 
market,  particularly  from  the  smaller  mines  that  are 
operated  only  on  the  high-priced  market,  is  not  pre- 
pared. The  tipple  as  built  at  Springdale  and  the  new 
tipple  about  to  be  constructed  at  Windsor  are  both  de- 
signed so  that  the  coal  may  be  picked  before  it  is 
weighed  for  the  miner  in  which  case  the  miner  will  be 
paid  only  for  the  clean  coal  which  he  loads.  The  pres- 
ence of  fire-clay  or  other  foreign  matter  which  fuses  at 
;>  low  temperature  has  a  ver\'  undesirable  effect  and 
considerably  reduces  boiler  capacity  and  in  addition 
lowers  the  efficiencv  on  account  of  the  increased  coke 


FIG.  2 — GENER.\L  VIEW  OV  I'OWER  ST.VTION,  OUTDOOR  SUnST  \T10.V 

from  1000  to  6000  kw,  normal  rating.  The  major  iiaii 
of  the  steam  is  produced  in  four  boilers  of  1372  hp  c.i 
p.'.city  each,  each  boiler  being  equipped  with  an  8800 
sq.  ft.  economizer  and  a  14-retort  stoker.  The  re- 
mainder of  the  steam  is  produced  in  thirty-two  Imilers 
each  of  372  hp  capacity. 

The  average  monthly  load  factor  on  the  West  I'enn 
System  is  about  63  percent.  The  average  load  factor 
in  the  Connell.sville  station,  on  account  of  its  being  the 
least  efficient  of  the  three  stations,  is  about  40  percent. 
The  base  load  factor  on  the  system  will  be  about  equally 
divided  between  the  Windsor  and  the  Springdale  plants. 
Lump  coal  to  the  amount  of  35  000  tons  is  at  pres- 
ent in  storage  either  on  the  ground  or  in  privately  owned 
railway  cars.  This  is  slightly  in  excess  of  two  months  re- 
quirements at  the  present  rate  of  consumption.  The 
West    Penn    Power    Company    during    the    recent    car 


.Mav,   II)-' I 


THli    lil.liCTRlC  JOURWll. 


^77 


.•-hiiitage  ]iurchased  seventy  35  ton  liopjier  cars  to  trans- 
port coal  for  this  power  house  and  which  were  specially 
designed  so  as  to  permit  the  removal  of  more  than  90 
]iercent  of  the  coal  by  means  of  grab  bucket.  This  is  a 
difficult  matter  in  the  ordinal^  hopper  car  as  there  are 
so  man\-  struts  that  the}-  interfere  wi'h  the  operation  of 
the  bucket.  These  cars  ha\e  lieen  loaded  with  lum|) 
coal  and  withdrawn  from  operation  until  the  ne.Kt  car 
shortage.  Fig.  i  shows  a  photograph  of  the  Connells- 
ville  iilant.  Two  20  ton  locomotive  cranes  are  utilized 
1  handle  the  coal  in  and  wut  of  storage.  The  company 
ha-  00  acres  of  low-lying  land  at  this  |ioint  which  is 
bting  utilized  for  ash  disposal. 

WINnSOl;    STATIOK 

The  \\'inds(jr  power  station  is  also  located  about 
35  miles  in  an  air  line  from  Pittsburgh,  l)ut  in  a  south- 
\\e>terl\-    direction.      The    installed    capacity   at    present 


being  provided,  which  will  elinnnate  the  present  railway 
between  tipple  and  power  hou.se  and  permit  storing  or 
reclaiming  140000  tons,  about  two  months'  .sup()ly  of 
coal  for  the  contemplated  capacity  of  this  station,  viz., 
si.\  30000  kw  units.  Work  on  these  improvements, 
having  a  maximum  capacity  of  500  tons  ])er  hour,  has 
been  started  and  thev  will  be  in  operation  before  the 
end  of  the  year. 

At  the  Windsor  power  station,  the  new  coal-hand- 
Img  scheme  will  deliver  coal  to  the  boiler  bunkers  direct 
by  means  of  l)ell  conveyors,  thus  effecting  a  very  con- 
siderable reduction  in  the  number  of  men  employed  to 
handle  the  coal  between  the  mine  o])ening  and  boiler 
bunkers. 

SPRINGDALK  STATION 

The  .'~^])ringdale  station  is  located  on  the  .\lleglieny 
River   about    thirteen   miles   in   an    air   line    from    i'itls- 


.\\D    rii.VNSM  ISSIO-X  TOWERS  .VT  VVINHSOH,  VVKSI   VIUC.lNIA 

consi>ts  of  four  30000  kw  units,  one  of  which  is  owned 
bv  the  West  Penn  Power  Company  ;md  three  liv  the 
r>hio  Pcjwer  Company.  Each  tiuTine  is  supplied  with 
steam  by  four  1262  hp  boilers,  each  ecpiipped  with  an 
8800  sq.  ft.  economizer  and  a  fourteen-retort  stoker. 
The  au.xiliaries  for  this  jilant  are  all  motor-driven,  the 
only  steam-driven  units  being  the  boiler- feed  pumps, 
each  generator  having  a  direct-connected  e.xciter. 
^\'ater  enters  the  economizers  at  from  too  to  120  de- 
grees. Power  for  the  auxiliaries  is  supplied  by  means 
of  house  transformers. 

The  tipple  from  which  the  coal  is  received  is  about 
one-third  of  a  mile  south  of  the  power  station,  con- 
nected by  steam  railroad  owned  and  operated  by  the 
power  house  company.  A  new  mine  opening  adjacent 
to  the  power  house  is  at  present  being  driven  and  a  new 
tipple,  belt  coal  conveying  and  storage  eciiflpment  are 


f'urgh.  The  initial  inst.allation  consi.-<ts  of  two  23000 
kv-a  units  and  five  132c)  hp  cro-s-tlrum  boilers,  \(^  tubes 
high  and  42  wide.  .\s  the  jiowerfactiir  on  the  West 
Penn  Svstem  is  around  00  percent,  both  the  \\'indsor 
and  Springdale  stations  are  o])erated  above  00  percent 
pov\er-factor,  the  lagging  current  being  absorbed  by  the 
Connellsville  power  station.  This  enables  the  machines 
at  Windsor  and  Springdale  to  be  run  at  practically 
unity  power-factor. 

The  rivers  in  the  Pittsburgh  District,  like  others 
ha\ing  a  c|uick  run-ol'f,  are  subject  to  ice  gorges  :md, 
especially  in  the  fall,  carry  large  quantities  of  le.aves 
and  debris.  The  intake,  when  operated  under  ordinary 
conditions,  is  div  ided  into  foiu"  sections,  two  up-stream 
.-.nd  two  down  as  -Ikiwu  in  l"ig.  12.  .Vs  each  unit  has 
lv\o  circulating  pump-,  one  circulating  pumji  is  supplied 
",ith  water  fiom  each  of  the  two  sections.     ( iates  are 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


provided  by  which  the  discharge  tunnel  may  be  closed 
and,  by  opening  other  gates  between  the  discharge 
tunnel  and  the  intake,  the  water,  after  passing  through 
the  condensers,  is  discharged  through  the  upper  intake 
section.  By  this  means  the  water  is  recirculated  dur- 
ing cold  weather.  This  arrangement  has  proved  very 
effective  at  the  Connellsville  station  in  overcoming  ice 
and  debris  troubles.  When  there  is  ice  or  debris  the 
water  flowing  in  the  river  has  enough  volume  and  the 
temperature  is  low  enough  to  allow  the  maintenance  of 
a  good  vacuum  provided  a  sufficient  quantity  can  be 
drawn  through  the  screens.  The  ice  readily  chills  the 
water  discharged  by  the  condensers,  permitting  it  to  be 
used  again.  Leaves  running  in  the  river  are  handled  bv 
the  rotary  screens  but  the  amount  to  be  removed  from 
the  circulating  water  is  reduced  by  recirculation.  In 
addition  to  the  advantages  of  recirculation,  the  double 
intake  system  permits  a  partial  cleaning  of  condensers 
by  shutting  down  one  circulating  pump  and  reversing 
the  flow  of  water  through  the  condenser,  thus  cleaning 
c-ne-half  of  the  inlet  section  of  the  condenser  head  at  a 
rime  while  it  is  in  service. 


pared  with  steam  driven  auxiliaries.  This  amounts  to 
an  average  saving  in  the  working  limits  of  the  plant  of 
two  percent,  besides  an  increase  of  two  percent  in  the 
output  of  the  main  units  on  account  of  the  smaller  per- 
centage of  the  main  unit  capacity  being  required  to 
supply  electric  power  to  the  auxiliaries  in  order  to  main- 
tain the  heat  balance. 

While  motor-driven  auxiliaries  are  more  desirable 
from  an  operating  and  maintenance  standpoint  as  ordi- 
narily supplied  with  power,  the\  are  not  so  reliable,  as 
they   introduce   one   more  link   between   the  source  of 


■ft.l^A^W^  •■'■^•i-^-yw^a^' 


,i— CKOSS-SKCTKiX     THROUGH     WINDSOR    POWER    SIATION 


It  vyas  thought  that  it  would  be  necessar)-  to  put  in  power  and  the  driven  unit.  To  overcome  this  difficulty 
a  hne  of  sheet  piling  to  divert  the  discharge  water  away  and  to  permit  the  operation  of  the  large  turbines  in  case 
from  the  intake,  but  the  present  quantity  of  water  being  of  failure  of  one  of  the  auxiliaries,  duplicate  circulat- 
handled  by  the  intake  is  such  a  small  part  of  the  river  ing  pumps,  condensate  pumps  and  air  pumps  are  pro- 
flow  that  this  has  not  been  found  necessarj-.  While  vided.  Either  circulating  pump,  when  run  by  itself, 
there  was  \ery  little  ice  last  winter,  the  indications  will  supply  approximately  two-thirds  of  the  amount  of 
are  that  the  Springdale  plant  is  very  favorably  located 
in  that  it  is  just  below  a  bend  in  the  river  and  the  ice 
and  leaves  seem  to  hug  the  farther  shore. 

Consideration  of   the   simplification   of  the  station, 
decreased  maintenance,  elimination  of  small  piping  with 


water  which  the  two  will  when  operated  together.  This 
mcreased  capacity  of  the  pumps  is  due  to  the  reduced 
frictional  resistance.  The  average  yearly  cooling 
water  temperature  is  about  55  degrees.  Nine  months 
in     the     vear    it     is     below     this     figure,     and     three 


the  consequent  reduction  of  steam  leakage  and  make-up  above,  so  that  for  a  greater  part  of  the  year,  even  when 

water  resulted  in  the  installation  of  motor-driven  auxil-  carrying  full  load  on  the  machines,  there  is  very  little 

i.iries  supplied  with  power  from  a  house  generator,  due  advantage  from  a  vacuum  standpoint  of  running  more 

to  the  increased  economy  of  such  an  installation  as  com-  than    one    circulating    pump.      The    condensate    pumps 


May,  1 92 1 


THE  ELECTRIC  J  OURS' A  I. 


pre  each  of  100  percent  capacity,  onl}-  one  of  these 
being  operated  at  a  time.  An  interruption  could  occur 
to  the  condensate  pump  for  several  minutes  without  the 
water  level  in  the  condenser  becoming  so  high  as  to 
affect  the  vacuum  on  the  machine  seriously. 

Each  condenser  is  provided  with  a  LeBlanc  air 
pump,  with  a  steam  exhauster  as  an  emergency  relay. 
It  was  at  first  planned  to  use  the  exhauster  to 
raise  the  water  for  priming  purposes  but,  on  account 
cf  the  complication  in  piping  and  the  liability  of  getting 
raw  water  mixed  with  the  condensate,  this  plan  was 
abandoned  and  separate  four-inch  steam  exhausters 
were  placed  on  each  condenser.  A  short  interruption 
to  the  air  pump,  as  with  the  condensate  pump,  is  not 
serious.  For  this  reason,  it  has  not  been  considered 
necessary  to  operate  duplicate  units,  as  the  duplicate 
unit  can  be  started  before  the  interruption  to  the  con- 
densate pump  or  air  pump  will  have  a  serious  effect  on 
the  main  unit. 

In  order  to  get  a  reliable  source  of  power  for  the 


house  generator  is  not  operating,  the  two  2200-volt 
busses  are  operated  in  parallel. 

The  motor-driven  exciter  set  is  duplicated  by  a 
sleam-driven  exciter  set.  As  the  thermal  efficiency  of 
the  house  generator  is  considerably  higher  than  that  of 
small  high-speed  turbines,  there  is  a  substantial  saving 
in  operating  even  the  boiler- feed  pumps  by  means  of 
motors,  although  a  turbine-driven  boiler-feed  pump  is 
provided  to  supplement  the  two  motor-driven  outfits. 
This  saving  amounts  to  an  average  of  100  kw  through- 
out the  range  of  capacity  of  the  pump.  The  control  of 
the  motor-driven  boiler-feed  pump  is  through  an  excess 
pressure  reducing  valve  in  place  of  the  ordinary  excess 
piesstu-e  valve  controlling  the  steam  supply  to  the  tur- 
bine-driven boiler-feed  pump. 

At  the  option  of  the  operator,  the  boiler  room  au.x- 
iliaries  can  be  transferred  from  one  bus  to  the  other  in 
case  of  failure  of  either  source  of  power.  While  from 
a'l  operating  standpoint  there  is  greater  liability  of 
trouble  if   the  house  generator  is   operated    in   parallel 


Ml       1       \IIU    III'    SPRIXCn.M.E  ST.MION   DURING   CONSTRUCTION 

)\ving  water  intake  at  the  left  and  mine  tipple  and  crusher  house  at  the 


right. 


electrically-driven  auxiliaries  and  to  prevent  a  total  in- 
terruption in  case  of  any  trouble,  two  separate  sources 
of  power  are  provided ;  viz.,  a  house  generator  and 
house  transformers,  one  circulating  pump  and  one  con- 
densate pump  being  supplied  from  the  house  generator 
and  the  others  from  the  house  transformers  which  step 
the  generator  voltage  down  from  1 1  000  to  2200  volts 
for  use  in  the  larger  motors  throughout  the  plant.  Prac- 
tically all  other  auxiliaries  have  two  sources  of  power 
and  can  be  transferred  from  one  to  the  other  in  order 
to  maintain  sufficient  load  on  the  house  generator  to 
heat  the  feed  water  to  210  degrees. 

These  include  the  low  service  pumps,  sump  pumps, 
boiler  room  auxiliaries,  motor-driven  exciter  set  and  the 
motor-driven  boiler-feed  pumps.  Both  the  motor- 
driven  exciter  and  boiler-feed  pumps  are  normally 
operated  from  the  house  generator  bus,  the  exciter  set 
being  tied  in  non-automatically,  but  protected  by  bal- 
anced relays  so  that  in  case  of  internal  trouble  it  will  be 
disconnected  from  the   source  of  power.     li^   case   the 


with  the  main  units,  yet  the  heat  balance  can  be  more 
closely  adjusted  when  all  generating  units  are  operated 
in  parallel.  This  may  be  done  automatically  if  desired  by 
I  he  installation  of  a  thermostatic  control.  If  the  house 
generator  and  house  transformers  are  tied  together, 
relays  are  provided  so  that  in  case  of  an  excess  output 
by  the  house  generator  it  will  be  disconnected  from  the 
house  transformers  and  carry  its  own  load  irrespective 
of  disturbances  to  the  house  transformers,  which 
might  cause  some  of  the  motor-driven  auxiliaries  con- 
nected to  the  house  transformers  to  drop  out  of  step. 
As  long  as  one  circulating  pumj)  is  in  operation,  vacuum 
can  be  maintained  on  the  main  unit.  Originally  it  was 
planned  to  install  check  valves  between  the  circulating 
pimips  and  the  condenser  in  order  to  prevent  one  pimip 
discharging  water  through  the  other  in  case  of  failure. 
Since  starting  up  the  plant,  it  has  been  found  that  the 
maximum  speed  at  which  one  of  these  circulating 
pumps  can  be  run  w-hen  reversed  and  running  as  a  tur- 
bine is  about  one-third  of  its  normal  operating  speed. 


i8o 


THE  ELECTRIC  JOURNAL 


Yo\    X\III,  No.  5 


This  would  mean  that  one-third  of  the  water  discharged 
by  the  circulating  pump  in  operation  would  be  by- 
passed through  the  reversed  circulating  pump  and  that 
the  condenser  would  be  supplied  with  about  one-half  of 
itt-  maximum  quantity  of  circulating  water.  Under 
average  conditions  this  would  reduce  the  vacuum  from 
20  to  28.4  inches,  which  would  not  cause  sufficient  ca- 
pacitv  reduction  to  affect  the  service  seriously. 

.\s  the  power  house  is  extended,  additional  house 
"generators  will  be  installed  which  will  have  sufficient 


full  load.  By  carrying  the  motors  which  require  the 
greatest  reliability  in  the  source  of  power  on  the  house 
generator  and  getting  the  additional  exhaust  steam  over 
what  the  house  generators  can  furnish  by  bleeding  the 
main  unit,  the  most  reliable  and  most  economical  ar- 
rangement of  power  station  auxiliaries  is  obtained. 

In  order  that  a  unit  can  be  started  quickly  in  case 
the  condenser  becomes  vapor-bound,  h\draulically-oper- " 
ated  gate  valves  are  provided  not  only  on  the  suction  of 
the  pump  but  on  the  discharge  as  well.     Tins  allows  the 


-CROSS-SECTinx  OK  Sl'IUNCD-M-E  ST.XTIOX 


capacity  to  carr}-  the  electric-drixen  auxiliaries  which 
are  most  vital.  The  remainder  of  the  exhaust  sleam 
will  be  provided  by  bleeding  the  main  turbogenerators. 
This  bleeding  will  be  required  only  at  loads  aboxe  the 
point  of  maximum  efficiency  of  the  main  unit  and  thus 
will  reduce  the  congestion  in  the  low  pressure 
stages  of  the  turliine.  as  experiments  show  that  a  con- 
siderable amount  of  steam  can  be  removed  from  the 
congested  area  of  the  main  turbine  without  increasing 
the  steam  demand.     This  is  only  true  at  approximately 


air  to  be  exhausted  from  the  circulating  pumi>  and  ihe 
\.ater  to  rise  so  as  to  cover  the  runner,  without  exhaust- 
ing the  vapor  from  the  condenser.  .\  hydraulically- 
operated  gate  valve  is  also  placed  in  the  discharge  line 
to  permit  of  repairs  to  the  condenser  at  times  of  flood 
water.  The  maximum  flood  stage  at  Springdale  is  32 
feet,  at  Windsor  52  feet  and  at  Cincinnati  72  feet. 

The  use  of  electric-driven  auxiliaries  affords  a  good 
ci[iportunitv  to  determine  the  amount  of  power  con- 
sumed bv  auxiliaries.     In  the  ^\'inds()r  station  the  per- 


!\Iay,  1 92 1 


THE   ELECTRIC  JOURNAL 


iSi 


centage  of  power  runs  from  atxjut  3J/  to  6^1.  percent  of 
the  total  power  generated.  The  estimated  consumption 
for  Springdale  at  various  loads  will  be  in  the  neighbor- 
hood of  6  percent.  The  percentage  of  power  used  by 
the  induced-draft  fan  is  approximately  unif(}rm  at  one 
percent  of  the  gross  output  of  the  station. 

The  reason  for  installing  induced-draft  fans  was 
that,  on  account  of  the  high  first  cost  of  the  boilers  in- 
stalled, it  was  desirable  to  secure  a  very  large  steam 
output  which  called  for  so  high  a  draft  that  the  onl}- 
practical  means  of  securing  it  was  by  means  of  induced- 
draft  fans.  In  addition,  there  is  no  individual  factor 
which  will  so  greatly  increase  the  maintenance  cost  as 
insufficient  draft.  By  the  installation  of  mechanical 
draft,  ample  spare  capacity  could  Ite  installed  to  take 
care  of  dirty  boilers.  This  excess  capacity  has  alread\' 
demonstrated  its  advisability. 


build  the  thinner  portion,  particularly  in  front  of  the 
lower  end  of  the  headers.  A  steel  plate  sloping  away 
from  the  combustion  chamber  has  been  placed  along  the 
fi'ont  of  the  mud  drum  and  the  brick  wall  bonded  or 
tied  to  this  plate.  The  hr^t  boiler  put  in  (jperation  has 
seen  some  eight  months'  service.  It  has  l)een  taken  oti' 
the  line  quite  fre(|uently  for  cleaning,  but  the  walls,  with 
the  exceptif)n  of  the  minor  change  to  the  top,  show  no 
signs  of  deterioratidu,  <o  tli.it  as  far  as  capacit}'  is  con- 
cerned the  walls  are  not  the  limit. 

Normally  twd  boilers  are  operated  to  carry  about 
-'2000  kw  load  on  one  machine,  or  in  excess  of  300  per- 
cent rating,  the  load  factor  on  the  unit  being  in  excess 
(  f  (So  percent.  The  furnace  teniperaluies  as  obtained 
In-  an  o|itical  |)yrometer  when  running  at  this  high  rat- 
ing are  below  28(10  degrees  F. 

/'oiler  Room  .lii.riliarics — .S])ace  has  l)een  prosified 


FIG,   () — IXTERIOR  OF  TURBINE  ROOM    .\T  SPRINCD.XLE 

Showing  cuiulcnscr  wells.  The  generator  leads  are  copper  bars  supported  on  23  000  volt  insulators  in  the  left  wall. 

The  boilers  are  designed  for  350  pounds  pressure,      in   the  station   for  economizers.     The  present   induced- 
and  235  degrees  maximum  superheat.     At  present  they      draft  fan  system  could  take  care  of  the  increased  draft 

lequired  by  the  present  boilers  when  equi]")])ed  with  eco- 
I'omizers,  as  the  gas  \(]lume  would  be  decreased  suffi- 
ciently to  offset  the  increased  draft  reipiired.  An  in- 
\estigation  of  the  stations  at  present  o])erated  by  the 
company  and  equipped  with  economizers  indicates  that 
the  installation  of  the  house  generator  in  these  stations 
\' ould  increase  not  onl\-  the  reliability  of  the  motor- 
(Irixen  auxiliaries  but  would  increase  the  economy  and 
boiler  capacit\'  of  j'/^j  percent  and  in  turbine  generator 
ca])acity  of  3  percent.  These  advantages  would  pay  a 
buuidsonie  return  on  the  additional  investment  required 
for  a  bouse  generator,  l)esi(les  having  the  additional  ad- 
vantage of  a  mure  reliable  source  of  power.  .\s  a  re- 
sult of  this  inxestigation  and  of  better  air  extraction  at 
210  degrees  it  was  decided  to  heat  the  feed  water  to  210 


are  being  operated  at  a  drum  pressure  of  325  pounds, 
and  are  delivering  steam  to  the  turbines  at  about  650  to 
^■75  degrees.  The  boilers  are  equipped  with  two  13- 
retort  stokers  with  double  clinker  grinders.  The  aver- 
age coal  at  this  plant  contains  about  10  jtercent  ash. 
With  coal  of  this  type  the  percentage  of  combustible  in 
the  ash  is  very  low,  even  in  ordinary  operati<in. 

In  the  first  four  boilers  installed,  the  front  header 
is  set  16  feet  above  the  giound.  The  front  and  rear 
walls  are  bonded  to  steel  framework  by  tile,  the  side 
v.alls  being  32  inches  thick  at  the  bottom  and  decreasing 
ti-  22  inches  at  the  top.  .All  four  walls  are  air  venti- 
lated, and  there  has  been  very  little  deterioration  oi 
v.alls  where  they  have  a  thickness  of  22  inches  or  more. 
In  the  front  and  back  walls  it  has  been  necessar\-  to  re- 


l82 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


degrees,  leaving  the  question  of  installing  economizers 
to  be  settled  at  a  later  date. 

It  was  found  necessary  to  provide  a  heating  system 
in  the  plant,  particularly  in  the  boiler  room  to  prevent 
a  general  freeze-up  of  instruments  and  piping.  For 
this  reason  the  instruments  are  placed  on  the  outside  of 
a  small  operating  room  located  on  the  main  boiler  room 
floor,  the  inside  of  the  room  being  heated.  The  vacuum 
system  of  heating  with  exhaust  steam  is  used. 

All  boiler  room  auxiliaries  are  driven  by  alternat- 
ing-current motors.  The  induced  draft-fan,  for  the  sake 
of  reliability  and  in  order  to  reduce  the  length  of  the 
shaft,  is  divided  into  two  sections.  Two  single-suction 
induced  draft-fans  are  installed  in  place  of  a  double- 
suction  fan,  the  two  fans  being  joined  by  a  flexible  coup- 
ling. Two  motors  drive  this  double  unit,  a  175  hp 
2200-volt  slip-ring  motor  on  one  end  and  a  400  hp 
2200- volt  slip-ring  motor  on  the  other.  The  175  hp 
motor  has  sufficient  capacity  to  operate  the  unit  to  325 
percent  rating,  and  is  connected  to  the  fan  by  means  nf 


nected  and  separated  by  dampers.  In  normal  opera- 
tion each  one  is  run  separately  while,  in  case  of  a 
breakdown,  the  dampers  are  opened  and  a  number  of 
boilers  are  operated  together  on  a  continuous  air  duct. 

The  fan  and  stoker  motor  controllers  are  operated 
by  pilot  motors  which  are  controlled  by  push  buttons 
on  the  main  control  board  or  directly  at  the  motor. 
The  pilot  motors  are  arranged  for  either  hand  or  auto- 
ir.atic  control.  At  the  present  time  two  boilers  are  be- 
ing equipped  for  automatic  control,  the  induced-draft 
f;;n  motors  and  the  stoker  motors  being  controlled  from 
the  steam  pressure  and  the  forced-draft  fan,  which 
permits  close  regulation,  being  operated  from  the  fur- 
nace pressure.  As  there  are  two  stoker  motors  per 
boiler,  the  control  for  these  stokers  is  designed  so  that 
the  relative  rate  of  feed  of  the  two  stokers  can  be  ad- 
justed by  hand,  to  allow  for  differences  in  fuel  require- 
ivients  of  the  two  sides  of  the  furnace. 

The  wind  box  of.  the  boiler  is  divided  into  eight 
sections,  each  having  its  own  damper  which  is  adiusted 


The  coal  is  conveyed  from  the 
tipple  on  the  power  house  side. 


Hf,.  7— (^KNER.M.  VIKW  OK  Sl'RINCU.\LE  I'OVVER  HOUSE,  ALLEGHENY  RIVEK, 

m  the  right  side  of  the  river  through  headings  in  the  coal  fjO  ft.  under  the  river  to  the 


a  unifle.x  coupling.  In  case  greater  capacity  is  rec|uire(l, 
or  the  drop  ihroughout  the  boilers  increases,  the  4(X)  hp 
motor  is  started  and,  when  brought  up  to  approximately 
the  maximum  speed  of  the  175  hp  motor,  the  second 
notch  of  the  control  cuts  out  the  175  hp  motor  and 
closes  the  circuit  of  a  magnetic  clutch,  transferring  the 
load  to  the  400  hp  motor.  This  arrangement  gives  in- 
creased reliability  and  economy,  as  the  175  hp  motor 
will  ordinarily  be  able  to  carry  the  full  output  required 
ci  the  boilers.  In  case  of  trouble  to  any  section  of  the 
fan  unit,  from  two-thirds  to  three-quarters  of  ma.xi- 
nnim  capacity  can  still  be  maintained  from  the  boiler. 

The  stoker  motors  are  three-phase,  60-cycle,  440- 
volt  induction,  pole-changing  type,  and  have  a  maxi- 
mum speed  range  of  4  to  i. 

The  forced-draft  fan  is  driven  by  a  175  hp,  three- 
phase,  2200-volt  brush-shifting  motor.  This  is  an 
alternating-current  motor  with  direct-current  character- 
istics. Only  one  motor  is  provided  per  boiler.  The 
forced-draft    air    ducts    for    the   boilers   are    inter-con- 


t(i  reduce  the  wind  l)ox  pressure  under  sections  of  the 
tire  that  are  too  thin. 

The  supply  of  air  to  the  boilers  is  a  problem  which 
i-  not  always  given  the  attention  it  deserves.  At  maxi- 
I'lum  rating  icx)000  cu.  ft.  of  air  per  minute  is  re- 
(|uired  for  each  boiler  at  the  Springdale  station,  while 
about  75  000  cu.  ft.  of  air  jier  minute  is  required  under 
(-rdinary  operating  conditicjns.  This  is  about  the  amount 
required  for  cooling  each  generator  and,  as  two  boilers 
will  carry  the  maximum  rating  of  each  generator,  the 
;>ir  for  the  boilers  next  the  turbine  room  is  taken  from 
the  discharge  of  the  generators,  while  the  air  for  the 
i  oilers  farthest  removed  from  the  turbine  room  is 
drawn  through  a  duct  from  the  outside.  In  this  way 
none  of  the  air  supplied  to  the  boilers  is  taken  from  the 
.,sh  cellar.  The  usual  arrangement  has  the  disadvantage 
that,  in  cold  or  fogg\-  weather,  the  vapor  in  the  ash 
cellar  becomes  so  thick  that  there  is  danger  of  accident 
ti,  the  operators,  especially  if  the  stokers  are  so  con- 
structed   that,    when    run    at    high    ratings,    the    gases- 


May,  1921 


THE   ELECTRIC  JOURNAL 


183 


escape  through  the  ash  pit  doors  or  openings  for  operat- 
ing mechanism. 

In  some  of  the  power  houses  of  the  West  Penn 
Power  Company  the  ashes  are  dumped  into  hoppers 
and  thence  into  narrow-gage  or  standard-gage  cars, 
transported  by  electric  or  steam  locomotive  and  dumped 
over  the  property.  With  such  arrangements,  when 
boilers  are  being  pushed  and  especially  at  times  of 
cleaning,  there  is  a  considerable  amount  of  corrosive 
and  combustible  gas  that  escapes  through  the  ash  pit 
doors.  At  times  when  the  fire  is  being  dumped  this  gas 
will  ignite.  The  action  of  the  heat,  together  with  the 
corrosive  action  of  the  sulphur,  has  a  destructive  effect 
upon  iron  work.  It  has  been  necessary  to  replace  some 
of  the  iron  work  in  these  plants  after  three  years'  use, 
or  to  cover  it  with  gunite. 

At  the  Springdale  station,  these  gases  are  all  con- 
fined and  there  is  no  iron  work  for  them  to  come  in  con- 
tact with.  No  gases  escape  into  the  ash  cellar  and  there 
i-  no  movement  of  air  in  the  ash  cellar  except  such  as  is 


available.  West  Penn  interests  own  lands  suitable  for 
the  disposal  of  the  ashes  and  rock  to  be  produced  from 
the  4000  acres  of  coal  controlled  by  their  affiliated  com- 
pany. Part  of  this  disposal  is  eighty  acres  of  land 
which  surrounds  the  power  house.  The  remainder  is  a 
ravine  adjacent  to  the  power  house,  where  an  ash  fill 
200  feet  deep  or  more  can  be  made.  When  it  is  neces- 
s;iry  to  use  this  latter  disposal,  it  is  possible  that  an 
aerial  tramway  may  be  more  economical  than  locomo- 
tive and  dump  cars  for  disposal  of  the  ashes.  The 
present  ash  loading  system  at  the  Springdale  power  sta- 
tion can  easily  be  modified  for  this  type  of  equipment. 
The  coal  tipple  is  located  about  250  feet  from  the 
power  house.  Coal  from  the  mine  or  from  the  track 
hopper  is  delivered  through  the  tipple  to  two,  but  ulti- 
mately three,  four-roll  crushers,  any  two  of  which  will 
l;ave  sufficient  capacity  to  take  care  of  the  maximum 
capacity  of  the  picking  tables  or  track  hopper.  The 
coal  is  screened,  the  fine  coal  by-passing  the  crusher  and 
dropping  upon  the  42  inch  inclined  belt  conveyor  lead- 


COAL   MINE  LOCATION,  TOWN   SITE,  SHOPS  AND   MATERIAL  HOIST 

The  town  site  and  coal  mine  are  located  on  the  opposite  side 
sington  is  shown  in  the  distance.  These  two  illustrations  form 

necessary  for  ventilation.  The  ash-handling,  instead  of 
being  one  of  the  most  laborious  and  unpopular  jobs,  is 
one  of  the  easiest  and  most  inviting  jobs  around  the 
plant.  One  crane  operator, in  two  hours  per  day  readily 
handles  the  ash  output  of  the  present  installation. 
However,  on  account  of  the  deep  excavation  that  has 
to  be  made  for  the  foundation  it  is  planned  in  the  ex- 
tension of  the  power  house  to  make  the  ash  pit  twice  as 
deep.  This  can  be  done  at  comparatively  little  additional 
cost.  With  the  present  stoker  operation  this  pit  capac- 
ity will  afford  several  days'  storage  for  ash.  In  the 
original  installation,  the  clinker  grinders  are  driven 
from  the  stoker  crank  shaft.  This  is  being  changed  in 
the  installation  of  the  fifth  boiler,  the  drive  being  taken 
off  the  speed  shaft.  This  will  permit  operatic  m  of  the 
grinder,  in  case  of  formation  of  excessive  clinkers, 
Vvithout  feeding  additional  coal  into  the  boiler.  The  ca- 
pacity of  the  coal  spouts  is  such  that  it  takes  one  and 
one-half  hours'  operation  of  the  stoker  to  empty  them. 
Ash   Disposal — Facilities    for   dumping   ashes    are 


of  the  river  from  the  Springil 
one  continuons  view. 


plant.  The  tovn-n  of  New  Ken- 


ing  to  the  bunkers,  the  crushed  lump  coal  dropping  on 
top  of  the  fine  coal  in  order  to  reduce  wear  upon  the 
belt.  As  each  boiler  is  stokered  on  two  sides,  three 
bunkers  are  necessary  in  the  plant.  The  bunkers  are  of 
the  suspended  type  and  have  a  total  capacity  of  about 
Foo  tons  per  boiler.  This  is  equal  to  about  five  days' 
supply  at  an  average  rating  or  ten  days'  supply  at  a  low 
load  factor. 

This  inclined  belt  has  a  maximum  capacity  of  500 
tons  an  hour.  For  the  present,  it  is  geared  down  to 
one-half  this  capacity.  There  is  a  250  ton  an  hour  belt, 
c.mveying  coal  over  each  of  the  three  bunkers,  the  coal 
being  distributed  throughout  the  length  of  the  bunker 
by  means  of  automatic  trippers.  As  the  coal  is  dis- 
charged from  the  top  of  the  inclined  belt,  a  sample  is 
taken  automatically.  This  is  crushed  in  a  coal  sampler 
and  five  percent  of  it  retained  for  analysis.  In  this 
way  a  continuous  record  of  the  coal  fed  to  the  power 
house  is  obtained. 

The  coal  is  fed  from  the  bunkers  to  the  boilers  by 


lS4 


THE   ELECTRIC  JOURX.U. 


\'(>I.   .W  in,  N( 


means  of  three  spouts  for  each  stoker.  The  spouts  on 
the  front  and  back  of  the  boiler  are  staggered,  so  that 
any  tube  in  the  boiler  can  be  drawn  from  one  end  oi-  the 
other  without  interfering  with  the  coal  spouts. 


^nrvsiK  riT 


Showing  railway  sets  and  control  for  hydraiilically-opcratcd 
iliarics  are  served  by  cranes. 

Preparations  are  being  made  at  S|)ringdale  for  a 
large  coal  storage.  The  present  i)lans  ])ropose  a  bridge 
of  250  to  300  feet  which  will  run  on  tracks  parallel  with 
the  ri\er  of  any  length  up  to  a  maximum  of  1300  feet. 
This  storage  will  be  extended  as  the  plant  develops,  .so 
as  to  keep  two  moiiths'  coal  requirements  on  hand  at  all 
tunes.  The  bridge  will  also  provide  a  means  of  unload- 
ing coal  brought  to  the  [ilant  in  barges  either  to  storage 
or  direct  to  the  track  ho|)per  and  thence  to  the  crushers 
and  power  hou.se  bunkers.  .\t  present  coal  is  handled 
to  and  from  storage  bv  means  of  locomotive  cranes. 


n  considerable  number  of  the  threaded  joints.  In  the 
later  piping,  wrought  iron  has  been  substituted  for 
steel,  as  more  perfect  threads  can  be  cut  in  the  wrought 
iron.  \\\  boiler  feed  piping  is  wrought  iron  with 
welded  Hanges  of  Soo-pound 
hxdraulic  standard. 

Pilot  gauges  are  used  through- 
out the  plant  to  indicate  steam 
jiressure.  Gages  record  the  pres- 
>ure  and  temperature  of  the  feed 
v\ater  and  steam,  the  temperature 
of  the  '  exhaust  steam  from  the 
main  units,  and  of  the  inlet  and 
outlet  circulating  water  and  con- 
densate. Boiler  meters  measure 
steam  tlcjw,  air  flow,  and  draft  in 
the  furnace  and  other  meters  meas- 
ure the  quantity  of  steam,  together 
with  the  pressure  and  superheat, 
su|)])lied  to  each  turbine. 

As  the  boilers  will  operate  at  a 
high  rating,  pure  feed  water  is  es- 
sential. .Ml  water  used  in  the 
|)lant,  other  than  circulating  water 
for  condensing  jiurposes,  will  be 
treated  with  lime  to  neutralize  the 
acid,  which  occurs  at  time  of  low 
flow  in  the  river,  and  also  with 
alum  and  then  filtered  and 
U)  produce  a  water  safe  for 
domestic  use.  This  treatment  will  jirevent  corrosion 
:nd  reduction  of  the  area  of  the  low  pressure  pip- 
ing throughout  the  plant.  The  make-up  water  for  the 
boilers  is  evaporated,  two  evaporators  of  10  000  pounds 
capacity  per  hour  each  being  installed,  which  when 
working  single  effect  will  supply  about  ^Yz  percent  of 
the  maximum  amount  of  water  required  by  the  generat- 


valves.   All  these  aux 
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FIG.    0 — COMPARISON    OF    POWER    REQUIRED    FOR    AUXILIARIES    WITH 
ELECTRIC  MOTOR  .\ND  STEAM  TURBINE  DRIVES 

The  plant  piping  is  simple.  All  steam  piping  four 
inch  and  larger  is  welded,  the  joint  first  being  van- 
stoned  and  equipped  with  flange,  which  is  recommended 
for- adoption  as  the  800-pound  hydraulic  standard.  On 
the  smaller  piping,  trouble  from  steam  leaks  has  been 
experienced  with  screwed  unions,  and  it  has  been  neces- 
sary to  go  to  an  Soo-pound  hydraulic  union  and  to  weld 


rir,.     10 — POWER    REQUIRED    FOR    AUXILIARIES    WITH    AND    WITHOUT 
INDUCED  DRAFT  FANS 

ing  equipment.  On  account  of  the  smaller  number  of 
steam-driven  auxiliaries,  the  make-up  is  probably  not 
rnich  in  excess  of  one-half  of  this  amount.  The  eva- 
]  orators  are  operated  between  two  pounds  back  pres- 
>ure    and    22^/1    inches   vacuum.     This    is    the   highest 


Mav,   lO-'i 


THE   llLF.CrRlC  JOURNAL 


185 


KIG.   II — ASH  BASEMENT 

Showing  submerged  hoppers  and  crane  with  1.5  cu.  yd.  per- 
forated grab  bucket  for  handling  ashes. 

porator  condensers  is  conducted  to  two  jet  condensers, 
where  it  meets  the  remaining  exhaust  steam  from  the 
lujuse  generator  and  is  heated  to  approximately  jh)  de- 
grees. 

The  statement  is  more  or  less  generally  made  that 


\acuum  which  can  be  obtained  in  the  evaporators  when  recessitated  redesigning  so  as  to  eliminate  expansion 
evai)orating  the  maximum  amount  of  water  recjuired,  troubles,  together  with  the  greater  maintenance  not  only 
using  the  condensate  from  the  main  turbines  as  cooling  of  the  turbines  but  of  the  reduction  gears,  were  given 
water.     The  condensate  after  passing  through  the  eva-      ,^,.^._^^  weight  in  deciding  to  install  the  house  turbine  and 

motor-driven  auxiliaries. 

( 'ne  evaporalor  has  lieen  opened  twice  in  the  eight 
months  it  has  been  uperaled.  When  first  opened,  there 
were  indication-,  thai  ilie  water  level  was  not  high 
enough.  After  Ibi^  had  been  increased  and  the  coils 
submerg.ed  and  the  evaporators  operated  for  another 
three  months,  they  were  again  inspected  and  no  more 
evidence  of  scale  was  found  than  could  be  removed  con- 
linuously  by  the  cracking  pnjcess.  The  amount  of 
water  evaporated  is  controlled  by  the  level  of  the  water 
m  the  evaporated  water  tank.  When  the  water  gets 
below  a  certain  level,  exhaust  steam  is  admitted  to  the 
evaporator  coils.  The  evaporated  water  tank  is  inter- 
connected with  the  jet  condenser  heaters. 

The  heaters  are  equipped  with  steam  ejectors, 
X'.hich  are  operated  for  the  dual  purpose  of  extracting 
the  air  and  of  running  at  a  slight  vacuum,  provided  the 
load  on  the  house  turbine  is  not  sufficient  to  heat  the 
feed  water  to  210  degrees.  The  exhaust  steam  from  the 
\'arious  ejectors  on  the  heaters,  evaporator  condensers 
and  from  the  main  units,  when  they  are  used,  is  col- 
lected in  a  surface  condenser,  the  condensed  steam  be- 
the  elimination  of  air  from  water  will  reduce  the  ing  returned  to  the  evaporated  water  tank  and  the  air 
amount  of  corrosion  in  boilers  and  economizers.  It  being  allowed  to  escape  through  a  \ent  to  the  atmos- 
was   with   this    idea   that   the   heat  in  t; 

and     evaporating     equipment     in    this  p.ji'-''    sUiy,  ,.  *  I'PPllJ 

plant  was  installed.  Tests  under  oji- 
erating  conditions  prev'ailing  in  the 
[ilant  during  the  latter  part  .of  Febru- 
ary and  March  1921  indicate  that  at 
approximately  210  degrees  there  is  a 
very  small  amount  of  air  in  the  water 
but  that  this  increases  rajiidly  as  the 
temperature  decreases.  There  is  a 
further  indication  that  practically  no 
.11  r  is  extracted  in  the  low-pressure 
e\a]iorators.  It  is  only  when  the 
water  is  heated  to  approxnnatelv  210 
degrees  at  atmosphere  pressure  that 
there  is  anything  like  a  complete  ex- 
traction of  the  air.  It  is  possible  that 
similar  results  may  be  obtained  at 
lower  temperature  and  corresponding 
absolute  pressures  but  as  yet  this  has 
not  been  demonstrated.  An  interest- 
ing fact  is  that  the  temperature  of  the 
exhaust  steam  from  the  house  genera- 
tor is  about  260  degrees  and  from  the  V 
boiler  feed  pump  is  about  400  degrees 

at    full   load,   showing  that,   with   the  '■"'  '3-ii  000  volt  ri.nc 

less  efficient  expansion,  the  steam  exhausted  from  these  phere.  The  condensate  from  the  main  turbines  is  used 
small  turbines  is  highly  superheated.  The  troubles  which      as  a  cooling  medium. 

previously  had  been  encountered  with  these  small  tur-  Our  experience  with  the  low-pressure  evaporator 

bines  when  supplied  with  high  temperature  steam,  which      \>-ould    indicate    that    a    single-effect    evaporator,    using 


FIG.  12 — WATER  INTAKE  AT  SPRINGDALE 

\ I  ihe  kit  (he  gates  are  shown  in  normal  position.  At  the 
-liiMMi  111  piisilion  to  recirculate  part  of  the  water  during  extreni 
|)iex  entiiig  freezing  at  the  screen.- 


right    ihey    are 
■Iv  cold  weather. 


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3 


S    AT   WINllSOR    I'OWER    STATION 


1 86 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


steam  between  the  limit  specified,  will  work  satisfac- 
torily and,  if  the  operation  is  given  proper  attention, 
will  be  self-scaling.  The  installation  of  a  single-effect 
evaporator  with  jet  condensor  heater  will  simplify  the 
station  piping,  reduce  the  first  cost  and  be  easier  to 
operate. 

Each  turbine  is  being  equipped  with  a  continuous 
oiling  system,  40  percent  of  the  oil  in  each  turbine  being 
passed  once  an  hour  through  a  filter,  having  a  maximum 
capacity  of  about  300  gallons  of  oil  an-  hour.-  Large 
oil  tanks  are  provided,  into  which  the  oil  from  any  ma- 


I  KensinEton   Frecpoi 


ELECTRICAL  INSTALLATIONS 

The  Connellsville  plant  was  started  in  1902  to  fur- 
nish 25  cycle  railway  service  to  the  original  properties 
of  the  West  Penn  Railway  System.  When  the  60  cycle 
rotary  converter  was  developed,  the  25  cycle  system  was 
abandoned  and  everything  changed  to  60  cycles,  as  this 
frequency  had  been  adopted  in  the  additional  installa- 
tions to  furnish  energy  for  lighting  and  power. 

The  switching  apparatus  in  this  plant  was  entirely 
overhauled  in  1916,  when  the  last  19000  kv-a  generator 
was  installed,  the  main  change  being  that  each  genera- 
tor was  given  its  individual 
transformers  and  arranged 
for  paralleling  on  the  high- 
tension  bus  only.  As  the 
transmission  lines  radiating 
from  this  point  are  all  for 
25  000  volts,  the  high-tension 
switches  operate  quickly 
enough  that  the)'  can  be  used 
^  for  synchronizing. 

This  same  arrangement 
has  been  followed  in  the  new 
Springdale  Plant  in  that  the 
main  use  of  the  11  000  volt 
bus  is  to  synchronize  the  gen- 
erators and  to  supply  power 
to  the  auxiliaries.  In  case  of 
emergency,  power  can  be 
transmitted  from  one  genera- 


^  Electrolyiic  Lightninc  Arrutar 
X  Choke  Coll 
*M  Pwtndal  Trantformct 
I  Currcal  Traiulonner 

Overload  Qreuli  Bin 
O  Hon-AuMfiMHo  Circuit  Breaker 


iiii 


FIG.  14 — M.MN  WIRING  DI.VGR.'VM  OF  SPRINGD.\LE  POWER  STAflO.N 

chine  can  be  emptied.  A  cen- 
trifugal oil  separator  is  pro- 
vided, to  clean  the  oil  under* 
these  conditions.  The  older 
turbine  oil  is  used  throughout 
the  plant  for  lubrication  of 
the  various  motor  and  auxil- 
iary bearings. 

A  machine  shop  is  pro- 
vided, in  which  the  following 
tools  will  be  placed:  48  in. 
lathe,  24  in.  lathe,  3  foot  6 
inch  radial  drill,  25  inch  post 
drill,  12  inch  and  4  inch  pipe 
threading  machine,  hack  saw, 
24  inch  shaper,  and  200-ton 
hydraulic  press. 

Particular  emphasis  has  been  placed  in  the  design 
of  the  plant  on  having  all  machinery  accessible  for 
handling.  The  circulating  pumps,  air  pumps,  exciters, 
railway  sets,  and  motors  are  all  provided  with  crane 
service  or  trolleys,  which  will  permit  of  readily  repair- 
ing these  various  units.  A  locker  room  and  wash  room 
for  150  employes  is  located  in  the  basement  close  to 
the  machine  shop.     A  small   sewage  disposal  plant  is 


uun  »^ 


provided  sufficient  for  250  to  300  employes. 


FIG.   15 — I)!ACR.\M  OF  SIATION  AUXILIARIES  AT  SPRINGDALE 

tor  to  the  transformers  of  another.  Where  the  132  000 
volt  switching  system  is  installed,  the  time  element  of 
closing  these  switches  is  too  great  to  permit  using  them 
for  synchronizing. 

The  Springdale  station  is  arranged  on  the  unit  sys- 
tem, each  main  generator  having  its  own  boilers,  auxil- 
iaries, transformers  and  bus  sections ;  thus  each  unit 
may  be  operated  to  full  capacity  entirely  independent 
from  every  other  unit.     However,  the  boilers  will  ordi- 


L 


Mav,   1921 


THE   ELECTRIC  JOURNAL 


iiarily  supply  steam  to  a  common  header,  and  the  main 
units  may  be  paralleled  through  reactors  on  the  1 1  000 
volt  bus,  or  directly  without  reactors  on  the  25  000  volt 
bus.  Power  is  generated  at  1 1  000  volts,  and  space  has 
been  provided  for  duplicate  11  000  volt  busses,  although 
only  one  bus  has  been  installed.  This  bus  and  the  main 
switches  are  on  the  switch  floor  and,  as  may  be  noted 
from  the  main  wiring  diagram,  there  are  switches  to 
connect  each  generator  and  each  transformer  bank  to 
the  bus  and  to  parallel  the  two  sections  of  the  bus 
through  reactors.  An  auxiliary  switch  located  under 
the  main  bus  connects  each  generator  directly 
U)  its  bank  of  transformers,  so  if  the  main  bus  or 
any  of  the  oil  switches  or  other  equipment  on  the  main 
bus  floor  should  fail,  or  if  it  is  necessar}'  to  work  on 
them,  the  service  may  be  maintained  by  connecting  the 
transformers  to  the  generators  through  the  auxiliary 
switch  and  disconnecting  the  main  switching  gear  by 
opening  the  disconnecting  switches. 

The  generator  voltage  is  stepped  up  from  1 1  000  to 
25  000,  at  which  voltage  power  is  transmitted  from  the 


FIG.    16 — OUTDOOR  TRANSFORMER   STATION    AT   SPRINGD.-'LE 

Including  seven  8333  kv-a,  II  000  to  25  000  volt  transformers, 
the  spare  being  located  in  the  middle;  and  four  1000  kv-a,  11  000 
to  2300  volt  station  transformers  connected  in  open  delta. 

station.  There  are  two  25  000  volt  busses,  designated 
ar,  the  "Main  Bus"  and  "Transfer  Bus".  Each  of  the 
transmission  lines  is  connected  through  an  automatic  oil 
switch  to  the  main  bus  and  through  disconnecting 
switches  to  the  transfer  bus.'  Space  is  provided  for  in- 
stalling oil  switches  later  to  connect  to  the  transfer  bus, 
if  operating  e.xperience  indicates  that  they  are  neces- 
sary. Each  transformer  bank  is  connected  to  the  main 
bus  through  an  oil  switch,  which  is  non-automatic,  ex- 
cept through  differential  relays  on  the  transformers. 
Each  of  the  two  sections  of  the  transfer  bus  is  con- 
nected through  an  automatic  oil  switch  to  a  transformer 
bank.  A  line  switch  can  be  taken  out  of  service 
without  an  interruption  by  closing  the  line  disconnect- 
ii!g  switches  to  the  transfer  bus,  and  the  automatic  oil' 
switch  connecting  the  transfer  bus  to  the  transformers, 
before  the  line  switch  is  opened.  The  oil  switch  con- 
necting the  transformers  to  the  transfer  bus  will  then 
serve  as  overload  protection  for  the  transmission  line 


which  is  operating  from  the  transfer  bus.  If  so  de- 
.sned,  all  lines  may  be  transferred  to  the  transfer  bus 
and  the  main  bus  disconnected  entirely  without  inter- 
rupting service. 

The  voltage  is  stepped  down  from  11  000  to  2300 
to  supply  the  station  auxiliaries.  There  are  two  2300 
volt  busses,  and  each  circuit  is  connected  to  either  bus 
through  an  automatic  oil  switch.  Each  bus  may  be 
supplied  from  the  house  generator  or  from  either  of  the 
two  banks  of  house  transformers,  and  each  circuit  may 
thus  be  supplied  from  an>'  or  all  of  the  three  sources. 
Ordinarily,  these  busses  will  not  be  operated  in  parallel. 
The  circuit  switches  are  interlocked  so  that  it  is  im- 
possible to  close  any  circuit  onto  both  busses  at  the  same 
time  unless  the  bus  tie  switch,  which  is  controlled  from 
the   operating   room,   is    closed.     Wherever   auxiliaries 


;-\\llCHI-S  FOR 
VOLT  bus 


SECTIONALIZINC  TIIK   II   000 


are  in  duplicate,  one  will  be  connected  to  the  house  gen- 
eiator  and  the  other  to  the  house  transformers,  so  that 
half  of  the  auxiliaries  will  remain  in  operation,  if  either 
source  of  power  is  interrupted.  Duplicate  2300  volt 
circuits  for  the  boiler  auxiliaries  are  taken  to  a  group 
switch  center  in  the  middle  of  the  firing  aisle,  where  the 
stoker,  forced-draft  and  induced-draft  motors  are 
controlled,  and  where  they  may  be  transferred  from  one 
2300  volt  bus  to  the  other.  In  a  similar  manner  circuits 
are  run  from  the  2300  volt  busses  to  group  centers  in 
the  condenser  pit,  where  the  turbine  auxiliaries  are  con- 
trolled. In  addition  to  the  advantage  of  reliability  ob- 
tained from  the  duplicate  circuits  and  apparatus,  and 
from  the  two  sources  of  supply,  this  arrangement  per- 
mits the  regulation  of  the  heat  balance  by  transferring 
load  from  the  house  turbine  to  the  house  transformers 


1 88 


THE   ELECTRIC  JOVRX.IL 


Vol.   Win,  No. 


or  vice  versa.  This  transfer  of  load  may  be  controlled 
from  the  operating  rooms  or  group  center. 

The  two  25  000  kv-a  generators  are  rated  at  1 1  000 
volts  and  have  a  reactance  of  ten  percent.  The  gen- 
erators are  star-connected,  with  the  neutral  of  each  gen- 
erator connected  to  a  neutral  bus  through  an  oil  switch 
;;nd  the  bus  is  grounded  through  a  resistance  of  four 
(  hnis.  The  generators  are  protected  by  balanced  re- 
lavs.  The  two  neutral  oil  switches  are  electrically  in- 
terlocked so  that  only  one  generator  may  be  grounded 
at  a  time. 

Each  generator  is  cooled  by  washed  air  supplied  by 
a  separate  fan,  the  air  washer  and  fan  being  in  the  gen- 
ciator  foundation.     This  air  is  taken  either   from  the 


FIG.    iS — ONK  SIDE  OF  23OO  VOLT  ST.\TION  BUS   STRIJCTl  RF. 

All  switches  are  in  duplicate. 

condenser  pit  or  from  the  outside  and  discharged  from 
the  bottom  of  the  generators  into  the  intake  to  the 
forced-draft  fans,  or  can  be  recirculated  to  warm  the 
turbine  room  to  prevent  condensation.  The  house  gen- 
erator is  rated  at  2500  kv-a,  2300  volts,  and  is  star-con- 
nected, with  the  neutral  connected  without  resistance 
to  ground  through  an  oil  switch. 

The  armature  of  each  generator  has  six  tempera- 
ture coils  embedded  in  it  for  indicating  temperature  on 
the  generator  switchboard  panels.  These  temperature 
coils  are  embedded  in  the  middle  of  the  slot  between 
the  top  and  bottom  conductors  and  operate  ammeters 
through  variation  in  resistance  of  the  coils  caused  by 
change  in  temperature.  Each  of  the  main  generators 
will  be  provided  with  steam  piping,  so  that  a  fire  in  the 


generator  ma}-  be  smothered  by  blowing  live  steam  into 
the  \entilating  passages. 

Load  indicators  are  being  installed  to  indicate 
automatically  the  total  station  load  at  all  times  at  four 
points  remote  from  the  operating  room,  namely : — 

I — Istation  superintendent's  oliicc 

2 — District  load  dispatcher's  office 

3 — Turbine  room 

4 — IJoilcr  room 

These  four  instruments  will  all  be  controlled  in 
l;arallel  by  a  contact  sliding  on  a  resistance  unit,  the 
contact  being  inoved  by  the  shaft,  which  operates  the 
pen  on  a  totalizing  graphic  wattmeter.  The  scheme  is 
based  on  the  principle  of  operation  of  a  potentiometer, 
the  indicators  at  the  remote  points  being  actuated  to 
move  so  as  to  balance  the  current  according  to  the 
position  of  the  sliding  contact  on  the  graphic  wattmeter. 
Each  distant  meter  must  take  a  certain  definite  posi- 
tion to  correspond  with  each  position  of  the  pointer  on 
the  totalizing  graphic  wattmeter. 

The  leads  from  the  generators  are  run  in  an  open 
bus  structure  and  supported  on  25000  volt  insulators. 
This  eliminates  the  cable  between  the  generators  and  the 
low-tension  bus,  with  the  attendant  possibility  of  shut- 
down resulting  from  cable  troubles,  and  permits  of 
ready  inspection.  The  floor  between  the  turbine  room 
and  the  switch  room  forms  a  conduit  gallery,  all  the 
control  cables  being  fastened  to  the  steel  floor  of  the 
switch  room.  The  controls  run  between  the  top  of  the 
trusses  and  the  floor  and  the  cross  controls  run  longi- 
ludinally  under  the  steel  floor  beams.  In  this  way,  the 
junction  boxes  not  only  give  access  to  the  control  cables. 
but  also  serve  as  the  vertical  connecting  link  between 
the  longitudinal  and  cross  control  conduit.  A  storage 
1  attery  is  provided  to  supply  current  for  the  switch  con- 
trols and  for  emergency  station  lighting. 

The  Windsor  Station  has  a  main  ring  1 1  000  volt 
b.us  into  which  the  four  generators  normally  feed  power 
with  reactors  rated  at  five  percent  at  30000  kv-a,  in- 
sialled  between  units.  There  is  also  a  reserve  1 1  000 
\olt  bus  to  which  any  generator  or  feeder  may  be  trans- 
ferred. The  1 1  000  volt  circuit  breakers  are  installed 
i"  concrete  cells.  Feeder  reactors  rated  at  three  percent 
,il  80  kv-a  are  used  in  the  feeder  circuits  which  suppl\' 
local  loads  near  the  plant.  Two  of  the  four  generators 
;ire  rated  at  30000  kw  at  unity  power-factor  and  the 
generator  field  is  the  limiting  feature  on  the  output  of 
these  machines.  The  other  two  units,  which  were  in- 
stalled later,  have  slightly  higher  capacity  fields  and  are 
rated  at  30000  kilowatts  at  90  percent  power-factor. 
Tlach  main  unit  has  a  210  kilowatt,  250  volt  direct-con- 
i.ected  exciter  which  may  feed  current  either  to  its  own 
generator  field  or  to  a  common  exciter  bus.  The  ex- 
citer for  each  unit  has  capacity  sufficient  to  supply  50 
percent  more  than  the  excitation  for  its  own  unit  and 
can  feed  current  into  the  excitation  bus,  which  may  also 
be  supplied  from  a  150  kilowatt  exciter  motor-genera- 
tor set.  The  station  electrical  auxiliaries  are  driven  by 
600  volt  motors,   which   are   supplied   from    1800  kv-a 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


189 


three-phase,  station  transformers,  which  reduce  the 
voltage  from  11  000  to  600.  The  various  stokers  and 
overhead  cranes  are  suppHed  at  600  volts  direct-current 
through  two  750  kilowatt  motor-generator  sets,  driven 
by  600  volt  alternating-current  motors.  A  third  similar 
set  is  being  installed  to  supply  600  volt  direct-current 
to  the  mine,  which  supplies  the  plant  with  coal  and  to 
the  Wheeling  Traction  Company,  which  is  an  affiliated 
company,  operating  street  railways  in  Wheeling,  and 
from  Wheeling  to  Steubenville.  The  generators  are 
star-connected,  with  neutral  connected  to  ground  with- 
out resistance,  the  neutral  switches  being  interlocked  so 
that  not  more  than  one  neutral  can  be  grounded  at  one 
tnne.  Each  main  unit  is  protected  against  internal 
failure  by  means  of  balanced  current  relays,  and  has  no 
protection  against  external  short-circuit  or  overload. 

A  fifth  generator,  which  is  a  duplicate  of  the  four 
existing  units,  is  now  being  installed  to  be  operated  as  a 
synchronous  condenser,  the  steam  end  of  this  unit  being 
kept  in  reserve  for  use  for  repairs  on  the  four  operating 
turbines.  Since  the  field  is  a  limiting  feature  on  the 
load  which  may  be  placed  on  these  units,  it  will  be 
possible  to  obtain  materially  more  kilowatt  load  from 
them  by  improving  the  power-factor  through  absorbing 
a  considerable  portion  of  the  wattless  current  by  the 
condenser. 


The  outstanding  features  of  the  more  recent  in- 
stallations of  the  West  Penn  System  are : — 

The  location  of  the  two  latest  stations  at  the  mine 
mouth,  thus  making  available  a  reliable  source  of  coal 
of  a  uniform  grade,  with  resultant  freedom  from  de- 
pendence on  transportation  systems. 

The  provision  for  ample  coal  storage  and  for  ash 
disposal  on  the  power  house  properties. 


The  reduction  to  a  minimum  of  the  labor  required 
for  the  handling  coal  and  ashes. 

The  use  of  motor  drive  for  auxiliaries,  thus  reduc- 
ing maintenance  and  simplifying  the  station  construc- 
tion. 

The  provision  of  duplicate  auxiliaries  and  sources 
of  power,  thus  eliminating  to  a  great  extent  shut-downs 
lesulting  from  troubles  w^ith  the  small  equipment. 

The  provision  of  clean  water  for  service  use  and  of 
distilled  water  for  boiler  use. 

The  handling  of  air  for  turbines  and  boilers  in  such 
a  way  as  to  prevent  condensation  and  the  formation  of 
vapor  in  the  ash  pits. 

The  elimination  of  excessive  air  from  the  feed 
water,  thus  reducing  corrosion  in  boilers  as  well  as  in 
the  economizers,  if  the  latter  are  installed  later. 

Cranes  or  trolleys  have  been  installed  over  prac- 
tically all  auxiliaries  to  reduce  to  a  minimum  the  time 
of  making  repairs. 

The  installation  of  the  highest  capacity  switching 
equipment  obtainable.  The  switches  for  the  electrical 
equipment  were  especially  designed  to  give  large  rup- 
turing capacity  and  provisions  are  made  to  cut  out  any 
switch  in  case  of  accident  or  for  inspection.  The  doors 
for  the  oil  switches  and  disconnecting  switches  are 
interlocked  to  prevent  an  attendant  from  working  on 
any  circuit  which  is  in  service. 

The  rendering  at  all  times  of  continuous  and  sat- 
isfactory service  to  the  customer  has  been  kept  con- 
tinually in  mind  in  designing  all  details,  beginning  with 
the  mining  of  coal  and  ending  with  the  delivery  of 
power  to  the  consumer. 

The  future  extensions  planned  are  large  enough  to 
t'ike  care  of  the  customers'  increased  demands  and  new 
business  for  several  years,  as  the  present  generating  sta- 
tions are  planned  for  ultimate  capacity  of  at  least 
t;oo  000  kilowatts. 


'   ,N  1 


ho  Ijulij^irmH  l''ioW 


'Nq^ 


J  'oJjJii 


Power 


G.  H.  GADSBY 

Vice-President 
West  Pcnii  Power  Company, 


THE  WEST  PENN  POWER  COMPANY  and 
electric  companies  affiliated  with  it  serve  a  terri- 
tory of  approximately  5000  square  miles  lying  in 
the  counties  of  Butler,  Clarion,  Armstrong,  Westmore- 
land, Fayette,  Allegheny,  Washington  and  Greene  in 
Pennsylvania,  and  the  counties  of  Hancock  and  Brooke 
in  West  Virginia.  With  the  exeception  of  Allegheny 
ajid  the  northern  half  of  Clarion  county,  the  chartered 
territory  comprises  all  or  the  greater  part  of  each  of  the 
counties  enumerated.  This  area  may  all  be  called  the 
Greater  Pittsburgh  District,  justly  renowned  as  the 
Workshop    of    the    world,    or   as    it    is    coming   to    be 


known,  as  the  Electrical  Workshop  of  the  World. 
Richly  endowed  by  nature  with  underlying  strata  of 
coal,  fire  clays,  limestone,  glass  sands,  silica  and  quartz 
rock,  and  with  mountains  of  stone  suitable  for  paving 
block  and  ballast  rock,  the  entire  district  is  the  scene  of 
great  industrial  development.  The  basic  character  of 
these  resources  contributes  to  the  stability  of  the  enter- 
prises which  have  been  founded  and  the  ready  supply 
of  finished  and  semi-finished  materials  which  enter  into 
the  production  of  important  articles  of  commerce  has 
attracted  many  industries  ;  and  the  development  thus  far 
has  been  but  a  good  beginning. 


190 


THE  ELECTRIC  JOURNAL 


Vol.  X\in,  Xo. 


The  proxiniin-  of  the  greatest  markets  in  the 
United  States  and  excellent  transportation  facilities  are 
additional  factors  contributing  to  the  importance  of  this 
territory  and  its  desirability  as  a  location  for  manufac- 
turing plants  of  wide  diversity.  A  glance  at  the  map 
accompanying  the  group  of  articles  concerning  the  West 
Penn  Power  Company  will  show  the  exceptional  trans- 
portation facilities.  The.  northern  part  of  the  territory, 
is  adequately  provided  for  by  the  Bessemer  &  Lake 
Erie,  Baltimore  &  Ohio,  Buffalo,  Rochester  and  Pitts- 
burgh, and  Pennsylvania  Railroads  and  is  also  served 
by  the  Allegheny  River,  which  has  already  been  made 
navigable  by  the  construction  of  government  dams  for  a 
distance  of  approximately  twenty  miles  above  Pitts- 
burgh. By  dams  now  under  construction  or  which  will 
shortly  be  begun',  the  river  will  be  canalized  as  far  as 
Kittanning.  The  main  line  of  the  Pennsylvania  Rail- 
road runs  through  the  territory  immediately  east  of 
Pittsburgh  on  a  line  through  Irwin,  Jeannette,  Greens- 
burg  and  Latrobe.  The  southeastern  section  is  pro- 
vided for  by  the  main  lines  of  the  Baltimore  &  Ohio 
Railroad,  the  Pittsburgh  &  Lake  Erie  and  the  Western 
Maryland  Railroad,  following  the  Monongahela  and 
Youghiogheny  Rivers.  The  southern  section,  in  addi- 
tion to  its  railroads,  has  available  water  transportation 
on  the  Monongahela  River,  which  has  been  canalized  to 
a  considerable  distance  south  of  the  Pennsylvania — 
West  Virginia  state  line.  The  southwestern  section  is 
just  being  developed  and,  as  this  development  pro- 
gresses, the  railroads  are  being  extended.  The  central 
part  of  Washington  County  is  provided  for  by  the  main 
line  of  the  Baltimore  &  Ohio  Railroad  west  and  the 
northern  part  of  this  county  is  served  by  the  main  line 
of  the  Pennsylvania  System  to  Columbus,  Cincinnati, 
Indianapolis  and  St.  Louis.  The  Ohio  River  is 
navigable  for  its  entire  length  and  during  the  past  year 
there  has  been  a  marked  resumption  of  river  traffic. 

Practically  the  entire  area  above  defined,  which 
vill  be  referred  to  as  the  West  Penn  Territory,  is 
underlaid  with  one  or  more  veins  of  bituminous  coal. 
In  the  order  of  their  outcropping  from  north  to  south 
are  found  the  following  seams: — 

Lower  Kittanning 

Upper  Kittanning 

Lower  Freeport 

L^pper  Freeport 

Pittsburgh 

Sewicklcy 

W'aynesburg 

The  high  quality  of  much  of  this  coal  for  use  in 
by-product  coke  plants  opens  a  vista  of  development 
along  lines  which  have  just  begun  to  be  exploited.  It  is 
expected  that  before  many  years,  with  this  rich  supply 
of  raw  material,  this  district  will  take  its  place  as  one 
of  the  leading  sections  producing  the  wide  variety  of 
commercial  products  for  which  the  materials  from  the 
"by-product  coke  plant  form  the  base. 

Except  for  the  territorial  lines,  it  is  not  possible  to 
separate  the  individual  central  station  companies  in  the 
'Greater   Pittsburgh    District.       The   marked   economic 


saving  b}-  interconnecting  large  central  stations  made 
possible  by  the  standardization  of  60  cycle  generation 
was  early  appreciated  and  through  numerous  intercon- 
nections of  considerable  capacity  and  the  co-ownership 
of  one  large  plant,  the  central  station  service  of  the  en- 
tire southwestern  part  of  Pennsylvania,  Panhandle  of 
West  Virginia,  and  eastern  Ohio  have  literally  been 
welded  into  one  solid  electrical  block. 

A  description  of  the  three  large  stations  of  West 
Penn  Power  Company  and  its  network  of  transmission 
hues  is  contained  in  accompanying  articles  in  this  issue 
of  the  Journal.  The  arrangement  of  these  stations  in 
relation  to  each  other  is  noteworthy,  forming  a  great 
triangle  in  the  center  of  the  territory  served.  The  pro- 
spective hydro-electric  development  on  the  Cheat  River, 
could  scarcely  have  been  placed  in  a  better  location  for 
the  future  development  of  the  southern  part  of  the  West 
Penn  territory,  just  beginning  to  be  opened. 

An  industrial  survey  made  a  few  years  ago  would 
have  shown  the  large  manufacturing  plants  and  indus- 
trial cities  located  along  the  banks  of  the  rivers  and  at 
places  where  a  fuel  supply  could  readily  be  had  or  large 
fuel  storage  provided.  With  the  development  of.  cen- 
tral power  station  service,  the  necessity  for  considering 
individual  power  plant  requirements  when  locating  fac- 
tories has  disappeared.  The  development  of  factories 
on  a  larger  scale  is  possible  by  reason  of  the  fact  that 
capital  investment  for  power  plants  is  no  longer  neces- 
sary for  factory  owners.  Emphasis  should  be  laid  upon 
this  point  because  it  will  frequently  be  found  that  the 
investment  by  the  central  station  to  serve  a  given  fac- 
tory is  greater  than  the  investment  in  the  factory  itself. 
'J'he  company  desiring  to  locate  and  build  a  manufac- 
turing plant  is  now  able  to  start  that  plant  on  less  capital 
or  put  in  a  much  more  economical  or  extensive  plant  on 
the  same  capital  in  territory  having  adequate  central 
station  power  service.  This  lessened  capital  investment 
makes  easier  the  financing  of  new  enterprises  or  exten- 
sions to  present  plants,  and  at  the  same  time  decreases 
the  risk  in  possible  loss  should  the  project  fail  to  earn 
its  way. 

The  West  Penn  Power  Company  is  essentially  a 
power  company.  While  it  does  serve  the  domestic, 
commercial  and  municipal  requirements  of  practically 
all  of  the  towns  and  cities  in  its  territory,  the  total  ca- 
pacity and  total  amount  of  energy  delivered  for  these 
purposes  is  exceeded  by  the  capacity  and  energ}'  de- 
livered and  used  for  industrial  power  and  heating.  The 
diversity  in  the  requirements  of  the  different  consumers 
!■-  a  big  factor  in  rate  making,  and  the  fact  that  there 
is  such  wide  diversity  among  the  consumers  of  the  West 
Penn  Power  Company  has  enabled  it  to  maintain  rates 
for  service  quite  comparable  with  those  of  large  power 
stations  serving  entirely  congested  city  districts  where 
the  density  of  load  is  several  times  that  existing  in  tli^e 
comparatively  open  country  which  comprises  such  a 
large  part  of  West  Penn  territory. 

With  something  over  50000  customers,  power  users 
constitute   scarcely   five   percent   of   the   total   number. 


May,  1921                                                 THE  ELECTRIC  JOURXAL  191 

Without  taking  into  account  the  power  service  supplied  ^iruction  shops,  miscellaneous  loading  equipment,  and 
to  its  affiliated  railway  companies,  75  percent  of  the  other  smaller  power  uses  incident  to  the  auxiliary  op- 
total  energ)'  generated  in  all  the  plants  of  the  West  erations  about  the  mine.  The  mining  loads  vary  from 
Penn  Companies  goes  to  this  five  percent  comprising  its  a  few  kilowatts  for  cutters  in  the  small  mine  working 
industrial  users.  It  is  estimated  that  the  population  in  iri  the  outcrop  to  huge  hoists  requiring  motors  as  large 
the  territory  served  by  existing  lines  is  over  550000.  as  i5oohp.  The  load  factor  of  the  mines,  depends  en- 
The  total  number  of  towns  and  communities  in  which  tirely  upon  the  power  required,  the  mines  having 
service  was  being  supplied  on  December  31st,  1920  was  comparatively  heavy  ventilating  and  pumping  require- 
324,  of  which  126  have  a  population  of  1000  or  over.  nients  operate  at  very  high  load  factors,  while  those 
The  West  Penn  Power  Company  does  not  sell  having  natural  drainage  in  non-gaseous  fields  using 
wholesale  energy  for  domestic  and  commercial  pur-  power  only  for  cutting,  hauling  and  incidental  uses  con- 
poses  but  is  organized  to  take  care  of  the  entire  process  ^nm^  power  during  fewer  hours  of  the  day.  An  aver- 
of  sale  to  the  smallest  ultimate  consumer.  This  is  ac-  age  of  all  mining  operations  would  show  a  load  factor 
complished  by  the  division  of  the  territory  into  a  num-  "l  -5  t^o  3°  percent. 

ber  of  districts,  each  district  centering  about  one  of  the  V,  hile  an  immense  amount  of  coal  has  been  taken 

largest  towns  located  therein.     Each  district  is  under  out  of  the  local  fields,  there  are  great  acreages  yet  un- 

the  direction  of  a  local  superintendent,  with  a  well  or-  touched,  particularly  in   the  southwestern  part  of  the 

ganized  office  and  field  force,  so  that  it  is  possible  to  territory,  and  it  now  appears  that  most  of  this  coal  will 

give  prompt  and  efficient  service  and  to  maintain  the  he  developed  by  large  companies  operating  completely 

quality  of  service  at  a  high  standard.  electrified  mines  of  from  one  to  ten  thousand  tons  daily 

The  increasing  use  of  central  station  power  by  new  cdpacit} . 

industries  and  through  the  replacement  of  other  sources  F™'"  the  standpoint  of  station  demand  and  energy 

of  power  supply  is  clearly  shown  by  the  growth  of  the  ^"onsumed,  the  electric  steel  companies  rank  next  to  the 

generating  capacity  installed  in  the  stations  of  the  West  '^"^l  "^'"^s.     This  includes  both  electric  furnace  plants 

Penn  System.     The  following  are  approximate  figin-es,  -"^  rolling  mills.     There  is  no  ;nore  interesting  story 

based  upon  name  plate  ratings  of  the  generators  in  all  ^han    that    of    the    electric    melting    furnace.     Definite 

of  the  stations  in  ser\-ice  : temperature  control  and  the  ability  to  make  high  grade 

1C05    6.000  kw  steels  from  cheap  scrap  have  placed  the  electric  furnace 

"J'°  I2S00  kw  in  a  field  of  its  own.     Furnaces  now  on  the  West  Penn 

191.S    51500  kw  .,                             .                 .                           ,,            ,                 •   ,     , 

IQ20 138000  kw  System  range  m  capacity  trom  small  100  kw  special  al- 

T,              tu  •    ^1     1     J          ■  A  u    n          t  ,.•        I  lov  furnaces  to  ten  ton  furnaces  making  castings  of  spe- 

1  he  growth  in  the  load  carried  bv  these  stations  has  ',         ,            ,                                         s            s           f 

J   •     ri                  <-•           1.-1    \\               <-•       1     J  cial  grades,  and  sheet  and  bar  steel.    While  the  cycle  of 

increased  m  like  proportion,  while  the  operating  load  .        '                                                                  v.j'    >.  « 

+v^t„„  „c  ^u      >.  t-        u      ■              AC                  ..  operation  of  a  steel  furnace  is  such  that  there  is  consid- 

tactor  of  the  stations  has  improved  from  year  to  year,  .....                                                        v-v^  ^  v* 

„„„    ■                           J-       •                •     »i     t  t  1       i     i    r  erable  variation  in  the  power  requirements  of  a  single 

meaning  a  corresponding  increase  m  the  total  output  of  .                         ^                                  " 

„„^          n      t    t  -A      u        u             j-tuj-         r  furnace,    the    continuous    use    and    custom    of    having 

energy.     Great  strides  have  been  made  in  the  design  of  .                                                        " 

u, „«.„,.  „  „*^        ^  tu  I.  tu       cc  ■       ■        Ui  •     J  r  several  furnaces  supplied  from  one  service  connection, 

large  generators  so  that  the  efficiencies  obtained  from  '^^                                                           ' 

the  new  stations  with  their  large  units  are  in  marked  '"^"^'^^  '^  P°-'*'^'^  ^°'  *^  ^^^^^  f"™^"  t°  "^""'^  ^  ^^'y 
contrast  to  those  secured  from  the  small  units  of  the  ^°°^  '°^^  ^^^f""""  ^^  '^  ^  '"""ted  question  whether  an 
earlier  period  of  the  Compa,:y's  histon'  and  also  to  the  ''^^'^'''  ^"'""^'^^  ""  '^""P^^^  ^''^  other  types  of  fur- 
small  units  or  steam  engines  in  the  few  I'emaining  iso-  "''*""  '"  *^  production  of  ordinary  commercial  steels, 
lated  plants  in  the  territory  today.  ^'  ''  ^  '.^^^  assertion,  however,  that  an  electric  furnace 
.  .  ,  '  .  ,  ,.  ,  is  superior  for  making  alloy  and  tool  steels.  There  are 
Approximately  50  percent  ot  the  power  supplied  ,  ,  ,  ^  ,  ,  ,,,  ^"  ,.  ... 
,  ,,  ,,r  .  Ti  -r.  ^  ■  ,  r  ■  ?t  least  ten  plants  on  West  Penn  lines  operating  electric 
by  the  West  Penn  Power  Company  is  used  for  mining  ,  ^                   _,                ,                   ,           ,  ,       r 

,      c-       ■      ■            1-    ,                  ,                  •             ,.  steel  furnaces.      1  hese  produce  not  only  steel  but  ferro- 

coal.     Service  is  supplied  to  more  than  400  mines  and  IS  „          r         ,■  ,     ,         ■               ,            , 

,.,.      ,  r        n                                ■     •  ,                   ,      ■   ■  alloys,  for  which  there  is  a  ready  market  among  steel 

utihzed  tor  all  power  purposes  incident  to  coal  mining.  .         ,,              ,                      '  „,       ^  ,,     ■.          „ 

c-               ■                            ,■    1      ,          ,               •  ,      ,,r  companies   all  over  the   country.     The   following  allov 

Some    mines     are     supplied     throughout     with     West  ,         ,  ^           „                     ,'  •      ,           ,           !=          - 

T-.                           ,         ,             .      ,    ,  r           .  ,     ,            ,  steels  and  ferro-alloys  are  made  in  these  plants: — 

Penn  power;  others  have  mixed  drives  with  the  tend-  "    ,.       ,.                       ^ 

Vanadium 

ency  towards  taking  all   the   service   from   the   Power  Molybdenum 

Company's  lines.     The  principal  operations  in  coal  min-  Tungsten 

...                  %                                ,                    .           ,  Chromium 

ing  requiring  the  use  of  power  are, — the  operation  of  Cerium 

ventilating  fans,  pumping  in  conjunction  with  the  mine  rnd  some  special  combination  alloys  made  for  specific 

erainage  systems,  electric  locomotives  drawing  the  mine  purposes.     This  district  is  the  largest  producer  in  the 

cars  from  the  rooms  and  entries  to  the  foot  of  the  shaft,  world,  of  some  of  these  alloys  notably  those  of  cerium. 

hoisting  (either  incline  or  vertical  lift),  coal  cutting  and  The  rolling  mills  are  coming  to  realize  the  possible 

loading  (the  latter  being  a  comparatively  recent  devel-  economy  in  the  use  of  purchased  central  station  power. 

opment),  the  operation  of  washers  and  crushers  where  The  West  Penn  Companies  now  supply  practically  the 

prepared  coal  is  shipped,  and  incidental  uses,  such  as  entire   requirements  of  three  plants  with   demands  as 

lighting,  operation  of  machinery  in  the  repair  or  con-  high  as  5000  kw  in  a  single  plant,  and  a  large  number 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


of  partial  nistallalion.?.  The  perfection  of  the  gear 
drive  was  a  Ion?  step  forward  in  the  use  of  electrically- 
driven  rolls  with  sixtv  cycle  power  service.  The  use 
of  motors  of  twelve  to  fifteen  hundred  horse-power  is 
by  no  means  unusual.  The  plants  served  produce  bars, 
sheet  and  shaped  steel,  corrugated  and  galvanized 
sheets,  and  tin  plate. 

A  comparatively  recent  innovation  is  the  use  of 
j.urchased  electric  service  for  annealing  furnaces.  The 
development  along  this  line  is  progressing  and  it  is  be- 
lieved that  the  day  is  not  far  distant  when  the  heating 
load,  consisting  of  the  high  temperature- electric  furnace 
and  lower  temperature  annealing  and  pre-heating  fur- 
naces, will  rival  the  motor  load  both  in  capacity  re- 
quired and  energy  consumed. 

In  point  of  demand  the  power  required  for  street 
railways,  both  affiliated  and  those  of  other  companies, 
is  next  in  importance.  Practically  every  electric  street 
and  interurban  car  in  the  West  Penn  territory  is  oper- 
ated by  West  Penn  power. 

The  glass  industiy  takes  the  next  largest  block, 
there  being  eighteen  companies  supplied  with  an  ever- 
increasing  demand.  This  is  a  most  desirable  load  for 
the  central  station  because  of  high  load  factor  in  the 
operation.  The  Pittsburgh  district,  originally  on  ac- 
count of  the  fine  sand  available  and  the  supply  of 
natural  gas,  has  developed  some  of  the  largest  glass 
plants  in  existence.  Research  work  "is  being  done  on  an 
electric  glass  furnace,  made  necessary  by  reason  of  the 
rapidly  diminishing  supply  of  natural  gas.  An  increas- 
••ng  load  is  anticipated  in  this  field. 

An  arrangement  of  industries  according  to  then- 
aggregate  demand  on  the  central  station  is  not  possible, 
but  as  correct  an  analysis  as  is  possible  would  indicate 
that  the  foundry  and  machine  shop  business  is  next  in 
importance,  closely  followed  by  a  large  number  of  brick 
plants  turning  out  an  excellent  quality  of  refractor}-, 
fire  and  building  brick.  By  reason  of  the  high  quality 
of  the  clays  and  shale  rock,  the  product  from  these 
plants  finds  a  ready  market  and  is  shipped  to  all  parts 
of  the  world. 

A  scarcely  less  important  group  is  the  pottery  and 
clay  products  industry-.  The  plants  in  this  district 
manufacture  not  only  the  customary  line  of  china  and 
earthen  ware  goods  but  there  are  some  plants  highly 
specialized  in  character  making  products  tributary  to 
the  other  major  industries  of  the  district,  such  as  spe- 
cial pots  for  glass  melting.  What  is  reputed  to  be  one 
of  the  largest  pottery  plants  in  the  world  is  located  in 
the  northern  end  of  the  West  Virginia  Panhandle  and 
is  largely  supplied  with  West  Penn  service. 

One  of  the  large  aluminum  plants  is  located  in  this 
territory  and  is  partially  supplied  with  purchased  power. 
There  are  a  few  chemical  companies,  three  radiator 
works,  seven  steel  fabricating  or  steel  construction 
plants,  one  large  cast  iron  pipe  mill,  several  rubber 
plants,  and  a  large  number  of  smaller  plants  making  all 
variety  of  products. 


Contributory  to  these  larger  plants  and  to  the  popu- 
lation brought  to  the  district  by  reason  of  these  mining 
and  manufacturing  interests  are  a  large  number  of 
laundries,  ice  cream  companies,  bottling  works,  packing 
houses,  printing  shops,  water  works,  by  far  the  greater 
part  of  which  purchase  their  power  supply. 

The  best  prospectus  of  any  territory  is  a  review  of 
v.hat  has  already  been  accomplished.  The  wide  di- 
versity of  successful  enterprises  in  this  district  is  the 
best  advertisement  of  the  district  for  attracting  new 
plants.  One  of  the  large  Pittsburgh  banking  institu- 
tions recently  made  a  careful  survey  of  the  resources 
and  facilities  afforded  in  this  district  for  specific  lines 
of  industry.  Taking  into  account  the  basic  products 
above  enumerated  and  remembering  the  excellent  trans- 
portation facilities  afforded  to  the  nearby  markets,  this 
district  offers  special  inducements  for  certain  lines. 
Thus  :— 

It  is  reported  that  out  of  lOO  chain  plants  in  the  United 
States  there  arc  three  in  the  Pittsburgh  district.  When  it  is  con- 
sidered that  an  immense  tonnage  of  rods  is  produced  here, 
shipped  elsewhere  and  manufactured  into  chain,  then  returned 
and  used  in  this  immediate  localit\-,  it  is  at  once  apparent  that 
this  is  the  logical  location  for  plants  of  this  character. 

Metal  lath  is  being  used  in  increasing  quantity  as  the  cheap 
lumber  supply  is  disappearing  and  the  superior  quality  of  metal 
lath  is  realized.  Out  of  forty  metal  lath  plants  four  arc  located 
in  Uie  Pittsburgh  district. 

Steel  lumber,  consisting  of  strip  steel  shaped  with  an  angle 
or  channel  on  one  edge,  was  first  made  in  1906  and  will  increase 
in  use  in  the  future. 

The  maker  of  show  and  display  cases  will  hnd  an  excellent 
supply  of  the  materials  required  made  close  at  hand.  There  arc 
three  such  plants  now  in  this  district  out  of  I/O  in  the  United 
States. 

Metal  ceiling  were  first  made  in  Pittsburgh  and  have  since 
come  to  be  used  extensively.  There  is  but  one  such  plant  here  out 
of  fifty  in  this  country. 

Wire  rope  should  most  profitably  be  made  here  with  the 
large  number  of  wire  mills  close  at  hand,  but  there  is  now  only 
one  out  of  forty  of  such  plants. 

Cans  and  tin  food  containers,  talcum  boxes,  tobacco  tins, 
and  like  articles  can  be  well  be  made  here,  although  there  are 
now  but  three  out  of  one  hundred  such  plants. 

Fire  arms  are  made  essentially  of  steel.  The  growth  of 
plants  of  this  character  has  been  a  matter  of  cusrom  and  pre- 
cedent rather  than  availability  of  the  raw  materials,  so  that  we 
now  find  that  out  of  twenty-seven  plants  in  the  country  none  are 
in  Pittsburgh. 

Surgical  instruments  are  also  a  steel  product  and  there  is 
but  one  plant  out  of  three  hundred.  There  is  one  plant  manufac- 
turing scales  and  balances  out  of  130;  one  making  refrigerators 
out  of  140;  no  printing  press  plants,  although  there  are  88  in  the 
country  requiring  large  steel  castings  and  metal  parts  of  all 
kinds. 

With  the  realization  that  better  goods  can  be  made  in  this 
county  than  abroad,  the  demand  for  domestic-made  toys,  into 
which  small  metal  parts  enter  so  largely,  will  be  a  growing  in- 
dustry in  the  United  States  and  the  proportion  of  eight  plants 
to  four  hundred  will,  without  doubt,  soon  be  materially 
increased. 

The  construction  of  steel  river  craft  will  resume  increasing 
importance  with  the  resumption  of  water  transportation  and 
facilities  afi'orded  for  plant  sites,  materials  required,  and  power 
supply  cannot  be  excelled  any  place  else  in  the  countrv-. 

Aeroplane  factories  will  soon  be  found  scattered  over  the 
country  as  automobile  factories  are  today.  The  Pittsburgh  dis- 
trict again  offers  the  raw  materials  and  may  be  expected  to 
have  a  large  share  of  these  plants. 

The  manufacture  of  metal  office  and  house  furniture  aiid 
house  trims  is  resuming  increasing  importance  and  here  again 
the  logical  location  for  such  plants  is  in  this  district. 

The  use  of  small  tractors  is  replacing  trie  horse-drawn 
equipment  on  the  farm,  by  the  contractor,  and  for  the  moving 
of  heavy  loads  even  considerable  distances.  There  is  one  plant 
here  producing  small  tractors  out  of  161  plants  in  the  United 
States  and  an  increase  in  this  type  of  factory  is  anticipated. 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


193 


As  has  been  pointed  out,  the  develoi)ment  of  cen- 
tral station  power  has  vastly  extended  the  area  avail- 
able for  plant  and  factory  sites.  Reference  to  the  map 
of  the  existing  transmission  system  shows  that  about  50 
[)ercent  of  the  West  Penn  Power  Company  territory  is 
now  supplied  with  power  service.  This  coincides  closely 
with  the  portion  of  the  territory  which  is  under  active 
mdustrial  development.  The  extension  of  power  lines 
follows  closely  the  beginning  of  development  and  in 
many  cases  is  the  first  step  towards  the  opening  of  new- 
sections  of  counti-y.  The- table  above  containing  the 
statement  of  installed  capacity  in  the  power  stations 
shows  the  rapid  rate  of  development  and  is  an  indica- 
tion of  what  may  be  expected  in  the  future.  ' 

State  regulation  has  removed  the  speculative  fea- 
ture in  utility  financing  and  placed  it  upon  a  sane,  con- 
servative, substantial  basis.  Recent  experience  of  the 
West  Penn  Company  has  demonstrated  that  adequate, 
reliable  service  is  recompensed  not  only  by  a  read}' 
market  for  its  services  but  by  a  spirit  of  co-oi-ieration  in 
the  communities  served  when  it  comes  to  financing  the 
requirements  of  the  Company.  It  is  believed,  there- 
fore, that  the  growth  of  the  central  station  companies 
will  keep  pace  with  the  industrial  requirements  and  that 
the  patrons,  present  and  prospective,  will  do  their  part 
in  the  necessary  financing  of  the  enlargements  and  ex- 
tensions required.  The  growth  of  the  electric  industry 
itself  is  well  known  and  each  year  is  producing  equip- 
ment and  devices  designed  to'  improve  the  quality  of 
service,  both  in  its  continuity  and  uniformity  of  char- 
acter.    At  the  same  time  the  manufacturers  of  electric 


utilization  equipment  are  constantly  producing  new  and 
r.iore  efficient  apparatus. 

The  plans  of  the  West  Penn  Power  Company  are 
tomprehensi\e  and  look  forward  several  years  in  the 
future.  The  present  stations  at  Springdale  and 
Windsor  are  constructed  with  enlargements  in  view  and 
it  is  expected  that  these  enlargements  will  come  forward 
with  regularity  and  according  to  a  fairly  definite  pro- 
gram based  upon  the  increased  requirements  for  service 
as  demonstrated  by  past  experience.  The  development 
of  the  water  powers  in  West  Virginia  will  add  a  large 
block  of  capacity.  The  transmission  systems  both  of 
this  Company  and  its  neighbors  are  laid  out  with  the 
idea  of  making  service  flexible  and  interchangeable, 
v.  hich  means  a  greater  possible  power  output  for  a  given 
amount  of  investment  and  an  increased  insurance  of  un- 
interrupted service  from  the  many  large  plants  well 
scattered  over  the  territory  supplied. 

The  projected  line  extensions  into  the  northern 
part  of  the  territory'  will  open  new  country,  increasmg 
the  production  of  plants  now  in  operation  and  making 
possible  the  location  of  many  new  industries  on  most 
desirable  sites  close  to  the  raw  materials  they  require. 

The  power  company's  function  is  to  sell  service  and 
the  managers  of  central  stations  have  come  to  realize 
that  its  successful  operation  depends  upon  service.  The 
result  is  an  increasing  co-operation  between  the  pro- 
ducer and  the  user  of  power  with  the  mutual  develop- 
ment of  the  central  station  compan}-  and  the  territory  it 
serves. 


'fee  Powea"^  StailDii^  of  Iax^  Dii^iKD^iio  Lij^lvi: 


J.  M.  GRAVES 

^  <;-,t.  Gene""^'  M"na'-er. 
Dnquesne  Light  Company 


AN  interesting  transformation  is  taking  place  in 
the  power  generating  system  of  the  Duquesne 
Light  Company.  Only  a  few  years  ago  ten 
power  stations  constituted  the  generating  system,  some 
of  these  producing  both  steam  and  electricity  for  sale. 
Some  were  considerably  isolated,  some  notoriously  in- 
efficient and  others  of  distinctive  characteristics. 

A  period  of  concentration  of  attention  on  the 
Brunot's  Island  station  then  started,  but  with  the  other 
plants  maintained  in  the  best  of  repair  and  operating 
condition.  Now  that  the  new  Colfax  Station  is  a  reality, 
all  attention  to  power  generation  centers  about  this  and 
Brunot  Island,  and  the  small  stations  are  little  used,  so 
far  as  power  generation  is  concerned.  In  contemplation 
of  this  change,  an  entirely  new  system  of  station  man- 
agement has  been  put  into  effect  at  the  large  stations, 
tut  there  is  no  attempt  to  do  so  at  the  small  ones.  A  map 
showing  the  location  of  these  plants  in  relation  to  the 


centers    of    population    in    and    around    Pittsburgh,    is 
shown  in  Mr.  Stone's  article  in  this  issue. 

BRUNOT    ISLAND 

The  inherent  difference  between  the  Colfax  and 
Rrunot  Island  stations  lies  in  the  fact  that  the  latter 
is  made  up  of  a  collection  of  relatively  small  generat- 
ing units,  both  boilers  and  generators,  while  Colfax, 
having  much  larger  units,  will  not  attain  the  same  per- 
centage of  flexibility  until  it  has  possibly  three  times  the 
installed  capacity  of  the  other  station.  The  boiler  room 
of  the  Brunot  Island  plant  includes  interesting  ex- 
amples of  what  was  considered  the  highest  attainment 
m  boiler  construction  at  the  time  various  units  were  in- 
stalled. The  original  plant  consisted  simply  of  a  build- 
ing separated  by  a  wall  in  the  middle  with  a  row  of 
boilers  on  one  side  and  a  row  of  engines  on  the  other. 


194 


THE   ELECTRIC  JOURNAL 


\<A.  X\"1I1,  Xo.  5 


All  apparatus  of  importance  was  located  on  one  eleva- 
tion, namely  the  main  floor,  and  the  matter  of  height 
and  depth  did  not  seriously  enter  into  the  station  design. 
Thus  the  original  boilers  were  500  rated  horse-power 
three  drum  construction  with  two  stokers  per  boiler. 
They  were  installed  separately,  with  two  boilers  con- 
necting into  a  seven  foot  steel  stack  130  feet  high.  No 
superheaters  were  installed  and  10  in.  steam  leads  from 
each  boiler  connected  to  an  18  in.  header  along  the  tur- 
bine room  wall.  Coal  was  supplied  by  a  larrj'  running 
along  the  floor  in  front  of  the  stokers,  and  ash  removal 
w  as  taken  care  of  in  a  relatively  small  cellar  under  the 
main  firing  aisle.  These  same  boilers  are  operating 
today,  and  with  the  addition  of  superheaters,  smaller 


with  underfeed  stokers.  All  of  these  are  supplied  with 
forced  draft  and,  for  this  purpose,  nine  fans  are  used 
to  serve  18  boilers,  the  fans  discharging  into  a  common 
air  duct.  Six  of  these  are  electrically  driven  by  125 
hp  variable  speed  induction  motors,  and  are  hand  con- 
trolled through  four  ranges  of  speed.  The  remaining 
three  are  driven  at  the  same  speed  by  turbines  through 
reduction  gears,  and  are  regulated  by  hand  throttle  con- 
trol only.  As  the  fans  operate  most  efficiently  when 
running  at  the  same  speeds,  effort  is  made  to  either  vary 
their  speeds  altogether  or  cut  out  fan  units  entirely  ac- 
cording to  changes  in  load. 

When  the  demand  for  more  steam  came  the  chain 
grate  stoker  was  enjoying  an  era  of  popularity,  and  ac- 


size  non-return  valves,  overhead  coal  supply,  under- 
grate  blowers  and  firing  instruments  they  are  perform- 
mg  very  satisfactorily. 

As  the  demand  for  more  steam  became  imperative 
600  hp  boilers  with  Roney  type  stokers  were  installed  in 
an  addition  made  to  the  original  building  and  operated 
for  a  number  of  years,  when  they  were  raised  and 
equipped  with  improved  underfeed  stokers.  These  also 
are  operating  at  the  present  time  at  an  average  rating  of 
about  190  percent  normal  and,  considering  the  improve- 
ments made  in  furnace  design,  they  constitute  a  very 
satisfactory  unit.  These  boilers  are  also  served  bv  steel 
stacks  175  ft.  high,  two  boilers  per  stack.  The  re- 
mainder of  the  boilers  in  this  row  are  822  hp  equipped 


FIG,    I — RRUNOT  ISLAND  POWER  STATION 

cordingly  a  new  addition  of  twenty  822  hp  boilers  with 
chain  grate  stokers  were  installed.  The  boilers  were 
installed  in  batteries  of  five  at  right  angles  to  the 
original  boiler  room  and  served  by  brick  stacks  208  ft. 
high  for  each  two  batteries  of  boilers.  This  made  a 
boiler  plant  covering  a  considerable  area.  In  fact 
83  000  sq.  ft.  of  floor  space  was  covered  by  37  7CX)  nor- 
iiial  rated  horse-power,  or  0.45  hp  per  square  foot.  An 
interesting  comparison  can  be  had  with  the  Colfax 
boiler  room  in  which  29  250  normal  rated  horse-power 
are  developed  on  36800  sq.  ft.  of  boiler  room  floor 
space,  or  0.8  hp  per  square  foot. 

The   steam  piping  in   a  boiler  room  of   this   size 
naturally    became    an    exceedingly    important    feature. 


Alav,   1 92 1 


THE   ELECTRIC  JOURNAL 


195 


Since  all  of  the  new  boilers  had  been  equipped  with 
superheaters,  delivering  steam  at  500  degrees  tempera- 
ture and  200  lbs.  pressure,  this  phase  of  development 
somewhat  outgrew  the  application  of  metals  to  steam 
pipe  fittings  and  valves.  Certain  accidents  in  the  failure 
of  fittings  in  other  plants  and  in  our  own  proved  beyond 
?.  doubt  that  the  general  use  of  highest  grade  steel  for 
valves  and  fittings  was  necessary.  Action  along  this 
hne  was  immediately  started,  and  at  the  present  time  a 
great  part  of  the  steam  piping  is  equipped  with  all  steel 
valves  and  fittings,  and  to  a  considerable  extent  the 
\alves  are  motor  operated.  Motor  operation  of  valves 
also  presents  a  unique  matter  of  judgment  as  to  what 
purpose  the  valve  motors  should  serve  primarily,  anc 
from  what  location  they  should  be  controlled.  The  be- 
lief prevails  that  the  motor  operation  of  these  valves  is 
desirable  from  the  standpoint  of  normal,  as  well  as  ab- 
normal operation,  and  additions  to  this  equipment  are 
being  made  at  the  present  time  carrying  out  this  idea. 
In  the  new  addition,  the  boilers  were  originally 
equipped   with   coal   scales   for  each   boiler,   but   in   the 


sitated  a  rather  complicated  layout  of  piping  which  is 
being  simplified  as  conditions  permit. 

It  is  interesting  to  note  the  contrast  in  the  exciter 
units  of  this  station  with  those  of  the  Colfax  Station, 
due  to  the  fact  that  where  continual  development  is  tak- 
ing place  all  system  and  order  of  arrangement  is  ob- 
literated. Exciters  are  placed  where  floor  space  best 
permits.  The  controlling  factor  as  to  whether  they  are 
sleam  or  electric  driven  is  a  variable,  depending  on  pre- 
\'ailing  ideas  at  the  time  when  more 
exciting  current  was  needed,  and 
there  was  no  ]irece(lent  to  [irevent  the 
installation  (jf  whatever  machine 
seemed  most  reliable.  The  majority 
of  the  auxiliary  apparatus  is  steam 
driven  and  the  quantity  of  exhaust 
steam  a\-ailable  is  such  as  to  provide 
an  excess  in  summer  just  about  equal 
to  the  deficit  in  winter.  This  is 
utilized  in  open  feed  water  heaters 
where,    up    to    the    present    time,    no 


-COLK.W    POWER    ST.XTION'    FROM    RIVi;R 


course  of  time  the  use  of  these  was  abandoned.  Each 
boiler  is  also  equipped  with  a  flow  meter,  CO.,  recorders, 
and  combination  inclined  tube  draft  gages.  The  under- 
feed boilers  are  equipped  with  boiler  meters  having 
sleam  and  air  flow  and  draft  indicators.  The  smaller 
boilers  are  being  equipped  with  CO.^  recorders  for  trial. 
The  important  feature  of  coal  handling  at  this 
station  is  a  100  000  ton  coal  basin  built  so  as  to  be  filled 
with  water  from  the  condenser  discharge  and  drained 
into  the  river  at  will.  Coal  is  received  both  by  rail  and 
river  and  weighed  into  the  plant.. 

TURBINE  ROOM 

This  is  one  of  those  plants  which  developed  to  its 
piesent  capacity,  rather  than  one  that  was  so  built.  A 
small  3000  kw  unit  and  a  40  000  kw  compound  unit 
break  the  monotony  of  the  other  15300  kw  units. 
There  is  a  fair  degree  of  uniformity  of  arrangement 
of  auxiliaries  throughout  the  condenser  cellar,  consider- 
ing the  changes  the  plant  has  undergone,  but  this  neces- 


definite  arrangement  has  been  put  into  ojieration 
whereby  the  station  heat  balance  is  entirely  under  con- 
trol. This  is  being  done  by  the  replacement  of  some 
steam  driven  auxiliaries  with  motor  drive,  and  bleeding 
steam  automatically  from  the  intermediate  of  the  com- 
pound unit  to  maintain  the  feed  water  at  2\2  degrees  F. 

This  station,  although  apparently  isolated  on  an 
island,  is  really  in  the  midst  of  Pittsburgh's  busiest 
manufacturing  district,  which  accounts  for  the  fact  that 
a  large  number  of  feeders  proceed  from  the  station. 
This  means  a  somewhat  complicated  switching  equip- 
ment and  a  feeder  board  that  requires  much  attention. 
1'he  operating  gallery  for  this  board  is  on  a  balcony 
projecting  out  into  the  turbine-room  in  such  manner  as 
to  command  a  good  view  of  the  entire  floor. 

Station  service  to  coal  handling  machinery  is 
through  rotary  converters  which  tie  in  with  the  city 
street  car  circuits.  A  250  volt  battery  is  maintained  for 
excitation  and  lighting  emergency,  and  in  general  every- 


iq6 


THE   ELECTRIC  JOURNAL 


\'ol.  X\'III.  \o. 


thing  possible  has  been  done  to  insure  continuity  of  ser- 
vice in  this  station*. 

THE   COLFAX   POWER  STATION 

The  present  and  uhimate  layout  of  the  Colfax  Sta- 
tion, is  shown  in  Fig.  4,  the  heavy  outline  showing  the 
portion  already  consti'ucted.  The  principal  equipment 
in  the  present  building  consists  of  seven  boilers,  one 
three-element  60000  kw  main  generating  unit,  three 
feed  pumps,  one  evaporator,  one  house  turbine,  one  heat 
balance  motor-generator  set,  two  stoker  motor-genera- 
tor sets  two  exciters,  one  bank  of  main  transformers 
and  the  necessary  oil  switches  and  auxiliaries.  There 
be  one  screen  house  and  one  main  feed  water  stor- 
-■ige  tank  for  each  two 
main  units.  There  is 
a  stack  for  each  four 
boilers. 

It  will  be  seen 
from  the  cross  section 
of  the  plant  Fig.  5 
lliat  the  main  three- 
|)  h  a  s  e  high-tension 
liusses  a  r  e  simply 
lieavy  cables  located 
over  the  t  u  r  b  i  n  e 
room,     and     that    the 


turn  the  main  bulk  of  the  boiler  feed  back  again  to  the 
boilers.  The  water  supply  in  the  Allegheny  River  is 
contaminated  to  such  an  extent  that  this  is  not  depended 
on  even  for  make-up  without  distillation.  An  eva- 
porator is,  therefore,  provided  for  this  purpose,  which 
gives  a  boiler  feed  of  100  percent  purity. 

There  is  complete  concentration  of  various  equip- 
laent,  from  the  standpoint  of  boilers,  general  station 
auxiliaries,  main  units,  electrical  equipment  and  water 
supply;  that  is  to  say  vertical  lines  drawn  through  the 
plant  completely  isolate  these  classes  of  equipment. 

STEAM  GENERATION 

In  the  design  and  arrangement  of  the  steam  gen- 
erating equipment  for  this  station,  the  best  modern  de- 
velopments in  central  station  practice  are  made  use  of, 
in  a  conservative  way.  Large  size  units,  with  ample 
total  capacity,  operation  at  efficient  ratings,  ease  and 
convenience  in  operation,  inspection  and  maintenance, 
are  the  main  points  arrived  at  with  this  equipment. 

The  boilers  are  of  the  cross-drum  type,  rated  at 
2088  boiler  horse-power,  each  with  20880  sq.  ft.  of 
heating  surface.  The  stokers  are  underfeed,  with  17 
retorts  per  boiler.  The  stoker  equipment  includes 
double-roll  clinker  grinders  for  the  removal  of  ash. 
Steam  is  generated  at  275  lbs.  gage  pressure  and  180  tle- 
grees  superheat  is  obtained  with  superheaters. 

Seven  boilers  are  installed  at  present  to  care  for 


..^-      .^:^&.  / 


addition  of  main  units  does  not  invoKe  the 
changing  of  feeder  circuits.  The  plant  is  designed  to 
operate  on  the  minimum  of  man  power  and  includes  as 
many  automatic  features  as  modern  power  station  de- 
sign seems  to  justify. 

In  this  station  we  have  a  power  station  within  a 
power  station,  as  far  as  prime  movers  and  electrical 
equipment  is  concerned,  the  boiler  plant  being  common 
to  both.  That  is  to  say,  a  house  turbine  drives  a  gen- 
erator on  a  separate  bus,  from  which  feeders  proceed  to 
the  various  auxiliaries  of  the  main  units  throughout  the 
plant.  Economizers  are  not  used  but  space  is  provided 
in  which  they  can  be  installed.     Surface  condensers  re- 

*A  more  complete  description  of  this  plant  is  given  in  an 
article  on  "Brunot  Island  Power  Station"  by  F.  Uhlenhant,  Jr 
in  the  Journ.al  lor  June.  '15,  p.  241. 


the  60  000  kw  turbogenerating  unit  and  steam  driven 
auxiliaries.  Seven  more  will  be  installed  in  the  near 
future  to  care  for  the  second  60  000  kw  unit.  In  nor- 
mal operation,  six  boilers  are  for  each  unit,  with  the 
seventh  in  reserve. 

The  boilers  are  arranged  in  two  rows,  along  a 
common  firing  aisle,  parallel  to  the  turbine  room.  The 
main  steam  header  is  placed  at  the  rear  of  the  row  of 
boilers  nearest  the  turbine  room,  and  five  feet  above  the 
boiler  room  floor.  The  stacks  are  arranged  in  pairs, 
each  pair  to  care  for  the  gases  from  eight  boilers,  or 
four  boilers  in  a  row  per  stack.  Two  boilers  on  each 
side  discharge  their  gases  into  a  common  breeching 
leading  to  the  stack.  These  are  steel  lined  and  self- 
supporting  on  the  steel  framework  of  the  building,  21  ft. 
inside  diameter  and  323  ft.  high  above  the  boiler  room 


May,   1 92 1 


THE   ELECTRIC  JOURNAL 


197 


floor.  Coal  is  spouted  into  each  stoker  hopper  from  a 
traveling  coal  larry  with  duplex  hopper  weighing- 
scales.  Theiarry  is  fed  through  down  spouts  from  the 
overhead  bunkers.  Ashes  and  refuse  fall  from  the 
,clinker  grinders  into  a  concrete  pit,  brick  lined,  sup- 
ported by  the  steel  framework  of  the  building.  Under- 
neath each  row  of  boilers  is  an  ash  track  at  the  ground 
level.  Each  ash  pit  has  three  sliding  doors,  operated  by 
compressed  air,  through  which  ashes  are  dumped  di- 
rectly into  gondola  cars.  Feed  water  lines  are  in 
duplicate.  The  main  feed  line  runs  underneath  the 
boiler  room  floor  from  which  risers  lead  upward  to 
each  end  of  drums.  The  auxiliary  feed  line  runs  above 
the  boilers  and  leads  are  takai  off  to  each  end  of  drums. 
The  main  and  auxiliary  lines  unite  just  before  entering 
drums. 

DIMENSIONS 

The  overall  dimensions  of  each  boiler  space  are  36 
ft.  wide  and  23  ft.  9  in.  deep,  center  to  center  of 
columns.     The  boiler  itself  is  34  ft.  wide  by  22  ft.  deep. 


tween  these  and  the  next  row  above.  These  two  rows 
are  of  No.  7  B.  W.  G.,  while  the  others  are  of  No.  8 
B.  W.  G. ;  all  of  hot  finished  seamless  steel. 

The  two  lower  rows  of  tubes  are  expanded  into 
short  and  straight  headers  separate  from  the  regular 
headers  above  and  connected  to  them  by  short  nipples. 
The  remaining  16  rows  are  expanded  into  vertical 
headers  of  the  usual  serpentine  form.  By  the  straight 
arrangement  it  is  hoped  to  prevent  the  formation  of 
slag  on  the  lower  rows  of  tubes,  which  is  always  a  seri- 
c  us  trouble  when  boilers  are  operated  at  high  overloads, 
and  especially  so  with  staggered  tubes.  All  headers  are 
provided  with  hand  hole  openings,  one  for  each  tube 
end.  The  spaces  between  the  headers  are  asbestos 
packed. 

BOILER  DRUMS 

The  drums  are  60  in.  diameter  and  34  ft.  long,  with 
shell  and  heads  of  1-1/16  in.  and  i^  in.  plate,  respec- 
tively. Longitudinal  seams  are  double  butt  strap  joint, 
triple  riveted,  and  circular  seams  are  lap  joint  double 


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FIG.   4 — PRESENT   .\ND   ULTIM.\TE   PL.\NT   OF    COLF.\X    ST.^TION 


tuft  Tm 


JI«^'~L 


i 


The  height  is  35  ft.  from  floor  to  center  of  drum,  and 
the  entire  height  from  bottom  of  ash  pit  to  top  of  steam 
lead  is  63  ft.  The  firing  aisle  is  23  ft.  9  in.  wide  and 
the  spaces  between  boilers  at  sides  are  12  ft.,  center  to 
center  of  columns. 

A  distinguishing  construction  feature  is  the  placing 
of  the  drums  and  uptake  at  the  front  of  the  boiler  in- 
stead of  at  the  rear.  The  gases  therefore  travel  from 
the  grate  surface  toward  the  rear  wall,  thence  upward 
through  the  first  pass  at  the  rear  of  the  boiler.  This 
arrangement  eliminates  the  necessity  for  a  heavy  wall 
ever  the  stoker  fronts,  and  tends  to  keep  the  hot  gases 
away  from  the  stoker  hoppers  and  air  distribution 
boxes.  As  a  part  of  this  arrangement  the  tubes  slope 
forward  instead  of  to  the  rear. 

BOILER  TUBES 

Each  boiler  has  918  tubes,  each  4  in.  diameter  and 
2C  ft.  long,  arranged  51  wide  and  18  high..  There  are 
also  two  rows  of  horizontal  circulating  tubes  from  the 
rear  header  to  the  drum.  The  two  lower  rows  of  tubes 
are  not  staggered  and  there  is  a  space  of  two  feet  be- 


riveted.  A  manhole  is  provided  in  each  end  of  the 
drum.  Feed  water  inlets,  one  at  each  end,  project 
above  the  water  line  and  discharge  through  taper 
nozzles  against  hemispherical  caps  which  break  up  the 
stream  into  circular  sheets,  thus  distributing  the  feed 
water  more  evenly  over  the  surface  and  preventing  the 
formation  of  currents  to  interfere  with  regular  circula- 
tion. The  steam  is  collected  in  a  dry  pipe  at  the  top,  ex- 
tending the  full  length  of  drum  and  is  drawn  off 
through  two  eight  inch  outlets  in  the  top  of  the  drum. 
Five  connections  for  safety  valves  lead  from  the  top  of 
the  drum,  with  ten  4.5  in.  safety  valves  providing  ample 
relieving  capacity  for  any  emergency.  The  steam  out- 
lets from  the  drum  lead  to  the  superheater  inlets,  one  at 
each  side  of  boiler. 

SUPERHE-^TERS 

The  superheaters  are  installed  in  the  usual  manner 
between  the  top  row  of  tubes  and  the  horizontal  circu- 
lators, and  extend  in  two  sections  the  full  width  of  the 
boiler.  An  inlet  and  outlet  for  each  section  is  pro- 
vided, one  at  each  side  of  boiler.     A  4.5  in.  safety  valve 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


May,  1 92 1 


THE  ELECTRIC  JOURXAL 


199 


is  installed  in  each  outlet.  Each  outlet  passes  into  a 
Y-connection  with  the  conesponding  outlet  from  the 
boiler  of  the  opposite  row,  and  the  two  pass  through  a 
common  lead  to  the  steam  header  below.  A  stop  valve 
and  non-return  \alve  in  each  outlet  prevent  any  possi- 
bility of  -reverse  steam  flow  into  boilers.  The  super- 
heating surface  is  6765  sq.  ft.,  and  the  superheat  may 
vary  with  the  output  from  130  degrees  at  rated  capacity 
not  to  exceed  200  degrees  at  highest  overload.  The 
superheat  will  be  180  degrees  at  200  percent  rating. 

BLOW-OFF  FACILITIES 

A  mud  drum  of  the  usual  forged  steel  box  type, 
8.25  in.  square,  extends  across  the  boiler  front  just  be- 
low the  lowest  row  of  tubes.  It  has  two  blow-down 
connections  with  blow-off  cocks  and  mud  valves.     The 


Fll      Ip      (   \I    OH    111!    _•(l'^S  HP  BOILERS 

Showing  stoker  and  stoker  gage  board  in  tront  of  ihc  boiler, 
and  soot  blowers  at  the  side. 

blow-off  lines  feed  into  a  common  header  which  can  be 
opened  either  to  the  river  or  to  a  storage  tank  in  the  ash 
cellar,  from  which  the  water  can  be  returned  to  service 
after  settling. 

STOKER  DRIVES 

Each  stoker  is  driven  by  a  20  hp  adjustable  speed 
direct-current  motor,  set  on  the  boiler  room  floor  at  the 
center  of  the  boiler  front,  and  connected  to  the  stoker 
crank  shaft  through  silent  chain  drives  and  double 
worm  reduction  gear  boxes.  Each  of  the  seven  sec- 
tions are  provided  with  throw  off  clutches  and  shearing 
pins  to  relieve  excessive  load.  The  rams  are  driven  by 
short  connecting  rods  from  the  ci»ank  shaft.  Links  on 
each  side  of  the  rams  connect  to  the  lower  push  plates, 
with  a  lost  motion  slide  and  lock  nuts  for  adjusting  the 
stroke  to  suit  the  fuel.  The  speed  ratio  of  the  motor 
to  the  crank  shaft  is  approximately  750  to  i,  and  the 


speed  range  of  the  motor  is  250  to  1175  r.p.m.  at  full 
load.  Each  of  the  17  stoker  ranis  handles  approxi- 
mately 20  lbs.  of  coal  per  stroke.  Thus  the  stoker  ca- 
pacity may  be  varied  from  6800  to  31  900  lbs.  of  coal 
per  hour  with  continuous  operation.  The  correspond- 
ing ratings  are  approximately  90  to  450  percent,  thus 
giving  extreme  flexibility  to  meet  all  possible  operating 
conditions. 

GRATES  AND  AIR  CONTROL 

The  grate  surface  proper  is  30  ft.  wide  by  13.5  ft. 
long,  making  a  total  grate  area  of  approximately  400 
sq.  ft.  Air  is  admitted  through  multi-opening  tuyeres 
from  the  air  box  underneath  the  retorts.  Cast  iron  coal 
extension  plates  round  over  from  the  lower  end  of  the 
retorts  into  the  clinker  grinder  pits.  The  pressure  in 
the  air  box  may  be  hand  controlled  by  dampers  leading 
f-i-om  the  main  air  duct.  Another  set  of  dampers  regu- 
lates the  air  supply  to  the  lower  part  of  grates,  while 
still  further  dampers  control  the  cooling  air  supply  to 
tlie  coal  extension  plates. 

CLINKER  GRINDERS 

The  double  roll  clinker  grinders  are  set  in  a  pit  five 
feet  below  the  lower  grate  surface,  which  insures  a 
sufficient  depth  of  ashes  to  keep  the  rolls  covered  at  all 
times.  Five  cast  iron  sprinkler  heads  project  18  in. 
above  the  rolls,  supplying  water  continuously  for  wet- 
ting down  the  ashes  and  clinker  before  they  reach  the 
lolls.  The  rear  wall  of  the  pit  is  protected  by  air 
cooled  cast  iron  deflector  plates  and  the  ends  are  lined 
with  fire  brick.  The  lower  part  of  both  front  and  rear 
pit  walls  consists  of  a  movable  apron,  pivoted  at  the  top 
with  the  lower  edge  reaching  down  to  the  center  line  of 
the  rolls.  These  aprons  are  held  in  position  by  arms  at 
the  back  and  have  worm  and  sector  adjustment  con- 
trolled from  the  boiler  room  to  adjust  the  distance  be- 
tween the  aprons  and  rolls.  The  rolls  are  supported  on 
cast  iron  bearing  blocks  bolted  to  the  structural  beam 
at  each  side  of  the  pit.  The  roll  itself  is  made  up  of  cast 
iron  split  sections  each  11  in.  diameter  and  20  in.  long, 
bolted  to  a  5  in.  square  steel  shaft.  Cast  iron  stub  teeth 
with  countersunk  square  heads  are  inserted  in  the  roll 
sections  from  the  inside  before  bolting  into  place.  The 
clinker  grinders  are  in  two  sections,  driven  by  10  hp 
adjustable  speed  direct-current  motors,  one  at  each  end, 
set  on  the  boiler  room  floor.  The  driving  mechanism 
consists  of  silent  chain  with  shearing  pins  to  relieve 
overload,  double  worm  reduction  gear,  crank  arm,  con- 
iiecting  rod,  rocker  arms,  and  ratchet  wheels  on  roll 
shafts.  The  extreme  speed  range  for  the  grinder  rolls 
is  from  0.6  to  9.6  revolutions  per  hour. 

TURNACE  AND  TLTBE  BANKS 

The  combustion  space  allowed  is  unusually  large, 
the  lowest  row  of  tubes  being  20  ft.  above  the  grates. 
At  the  fire  line  the  furnace  lining  consists  of  ventilated 
blocks  backed  by  air  spaces  supplied  with  air  from  the 
main  air  duct.  Above  the  fire  line,  high-grade  refrac- 
tory brick  is  used.     One  door  in  each  side  wall  and 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No. 


four  in  the  rear  wall  allow  easy  access  to  the  furnace 
for  inspection  and  care  of  the  fire.  The  horizontal 
baffle  is  laid  on  top  of  the  second  row  of  tubes  to  pro- 
tect it  from  the  direct  action  of  the  fire.  Vertical 
baffles  divide  the  tube  space  into  three  passes,  which  are 
proportioned  to  give  proper  passage  area  as  the  gas  be- 
comes cooled.  The  uptake  has  an  effective  area  of  135 
sq.  ft.  Double  leaf  balanced  dampers  in  the  uptake 
control  the  stack  draft.  Balanced  draft  regulators 
control  the  position  of  the  dampers  automatically  so  as 
to  maintain  the  proper  draft  over  the  fire  under  all  con- 
ditions. 

SOOT  BLOWERS 

Soot  blowers  are  installed  for  blowing  soot  from 
the  tubes.  Nine  elements  are  arranged  m  duplex,  with 
steam  supplied  at  each  side  of  boiler  and  the  elements 
meeting  at  the  center.  Steam  is  taken  from  the  auxil- 
iary steam  header.  Operation  of  each  element  three 
times  per  day  keeps  the  tubes  clean  and  free  from  soot. 

BOILER  INSTRUMENTS  AND  INSTRUMENT  BOARDS 

An  instrument  board  is  installed  at  the  front  of 
each  boiler,  facing  the  firing  aisle.     Mounted  on  this 


ing  130000  pounds  of  steam  per  hour,  the  value  of  im- 
portant variables  will  be  as  follows : — 

Wind  box  pressure  3.2  inches  of  water. 

Superheat  154  degrees  F., 

Speed  of  stoker  shaft  210  r.  p.  m.. 

Amount  of  air  to  stoker  5,,wo  cu.  ft.  per  minute. 

Combined  boiler  and  furnace  efficiency  77  percent, 

Flue  gas  temperature  470  degrees  P., 

Amount  of  coal  burned  by  each  boiler,  5.7  tons  per  hi 

Flue  draft-0.7  inches  water. 

The   automatic    control    of    the   boilers   is   accom- 
plished by  means  of  the  separate  variables: — 

I — Pressure  differential  in  fuel  bed.  and 

2 — Pressure  differential  in  tube  banks. 
The  first  is  controlled  by  steam  pressure  through 
the  regulators  on  the  forced  draft  fans,  and  is  the 
[irimary  variable,  i.e.,  air  is  supplied  to  the  fuel  bed  in 
proportion  to  the  demand  for  steam,  and  as  secondary 
operation  the  stack  damper  is  adjusted  by  means  of  the 
balanced  draft  apparatus  to  meet  the  demand  of  the  fuel 
bed.  The  third  or  independent  variable  is  the  rate  of 
feeding  coal  to  the  boiler  which,  of  course,  does  not 
vary  as  rapidly  as  the  air  supply,  and  is  entirely  under 
the  control  of  the  stoker  operator.  The  COo  recorder 
is  a  valuable  guide  in  the  regulation  of  the  air  supply. 
An  exception  to  the  above  sequence  is  had  when 


FIG.   7 — DUPLEX -DRrVEN  EXCITERS  AND  HEAT  B.\T..\NCE  MOTOR-C.KNKRATOK    SET 


board  are  the  two  steam  gages,  one  on  eadi  water 
column;  draft  gages,  showing  drafts  at  the  damper, 
over  the  fire,  and  in  the  air  box  under  the  grates;  two 
venturi  meters,  one  on  each  main  feed  line;  and  an 
automatic  CO,  recorder.  At  the  foot  of  the  board  are 
the  drum  controllers  for  the  stoker  and  clinker  grinder 
motors.  Pilot  lights  mounted  on  the  board  serve  to 
illuminate  the  various  instruments  and  to  indicate  when 
current  is  available  for  the  operation  of  motors.  The 
drafts  are  automatically  regulated  to  keep  the  air  pres- 
sure at  the  fire  the  same  as  in  the  boiler,  to  prevent  air 
leakage  through  the  doors.  Another  large  instrument 
board  spans  the  firing  aisle  and  on  it  are  mounted  a 
clock,  a  master  steam  gage,  and  a  station  load  sign ; 
all  with  double  faces  and  illuminated  dials.  These 
three  instruments  are  thus  made  visible  the  entire 
length  of  the  firing  aisle. 

BOILER  PERFORMANCE 

The  combined  performance  of  boilers  and  stokers 
are  as  shown  in  Fig.  8.     When  each  boiler  is  generat- 


the  damper  adjusts  itself  to  a  condition  of  the  fuel  bed 
which  may  have  been  brought  about  by  the  stoker  opera- 
tor, and  in  this  respect  is  not  dependent  on  steam  pres- 
sure variations. 

MAIN   UNITS 

The  ultimate  station  will  accommodate  six  main 
units.  The  present  building  will  accommodate  two 
units,  and  at  the  present  writing  one  unit  is  operating 
j.nd  the  installation  of  the  second  is  progressing.  These 
are  of  the  cross-compound  type,  capable  of  delivering 
60  000  kw  continuously,  and  overloads  up  to  70  000  kw 
for  a  shorter  length  of  time,  when  supplied  with  steam 
at  265  lbs.  gage  pressure  and  175  degrees  F.  superheat. 

The  unit  is  divided  into  three  elements,  one  high- 
pressure  single-flow  reaction  turbine  operating  at  1800 
r.p.m.,  and  two  low-pressure  semi-double  flow  turbines, 
one  on  each  side  of  the  high-pressure  element  operating 
at  1200  r.p.m.  Normally  the  total  steam  consumed  by 
the  entire  unit  passes  through  the  high-pressure  ele- 
ment, and  is  delivered  by  means  of  overhead  pipes  to 


.May,   1921 


THE   Rl.F.CTRlC  JOURNAL 


each  of  the  low-pressure  elements.  The  unit  is  de- 
signed so  that  at  full-load  each  element  carries  20000 
k\v,  and  the  inlet  pressure  to  the  low-pressure  elements 
is  about  55  lbs.  gage.  The  steam  supply  to  the  entire 
iiiiit  is  normally  controlled  by  the  governor  on  the  high- 
[u-essure  element,  but  each  of  the  low  pressure  machines 
is  equipped  with  a  governor  admitting  live  steam  di- 
rectly, when  desired  to  operate  them  independently,  thus 
to  some  extent  giving  the  flexibility  of  three  separate 
units. 

The  arrangement  of  the  governors  on  the  high- 
pressure  and  low-pressure  elements  is  such  that  unin- 
terrupted operation  of  each  element  is  possible  in  case 
one  or  both  the  other  elements  should  be  shut  down 
by  the  tripping  of  the  automatic  stop  from  any  cause 


FIG.  8 — CALCULATED  PERFORMANCE  CURVES  OF  2088  HP  BOILERS  AND 
17  RETORT,  21  TUYERE  UNDER-FEED  STOKERS 

not  effecting  the  other  elements.  For  example,  if  one 
of  the  low-pressure  elements  be  shut  down  due  to  over- 
speed  or  other  cause,  the  high-pressure  element  will  ex- 
haust into  the  remaining  low-pressure  element,  and  the 
excess  of  steam  will  be  discharged  to  the  atmosphere 
through  a  25  inch  relief  valve  set  to  open  at  about  60 
pounds.  In  this  case,  the  high-pressure  governor  can 
be  adjusted  to  supply  only  as  much  steam  as  the  remain- 
ing low-pressure  element  can  use.  In  case  both  low- 
pressure  elements  are  shut  down  the  high-pressure  ele- 
ment can  continue  in  operation  exhausting  to  atmos- 
phere. Or  if  the  high-pressure  element  alone  is  shut 
down,  either  or  both  the  low-pressure  elements  can  con- 
tmue  to   operate,   taking  high-pressure   steam   directlv.' 


.\ny  departure  from  normal  operation  is,  of  course, 
possible  only  at  a  sacrifice  in  efficiency.  The  perform- 
ance of  this  unit  when  running  normally  is  shown  in 
Fig.  10. 

TURBINE  INSTRUMENT  BOARD 

Each  unit  has  its  own  gage  board  on  which  are 
mounted  all  electrical  and  mechanical  instruments 
needed  for  operation.  This  includes  two  recording  flow 
meters,  two  recording  and  integrating  venturi  meters 
measuring  the  discharge  from  the  condensate  pumps, 
two  mercury  manometers  and  various  pressure  and 
temperature  indicating  and  recording  instruments. 

Indicating  watt-meters  and  sjnchroscopes  are  also 
mounted  on  this  board,  the  latter  enabling  the  turbine 
attendant  to  adjust  the  machine  speed  by  hand  previous 
to  synchronizing,  in  case  the  governor  control  motor 
cannot  be  operated  by  the  switchboard  attendant. 

TURBINE  OILING  SYSTEM 

The  high-pressure  oil  for  the  governor  relay  and 
the  circulation  of  oil  to  the  bearings,  etc.,  is  supplied  by 
a  high  and  low-pressure  oil  pump  on  each  of  the  three 
elements,  driven  from  the  governor  shaft.  In  addition 
there  are  two  steam  driven  auxiliary  pumps,  the  opera- 
tion of  which  is  controlled  by  floats  so  that  in  case  the 
main  oil  pumps  do  not  provide  sufficient  pressure  these 
auxiliaries  are  automatically  cut  into  service.  The  oil 
coolers,  three  in  number,  are  of  the  vertical  water  tube 
type  and  of  such  size  that  one  cooler  will  provide  suffi- 
cient cooling  surface  in  case  of  emergency.  The  valves 
are  arranged  so  that  any  cooler  can  be  cut  out  of  service 
during  operation,  but  no  matter  in  what  position  the 
valves  are  placed,  it  is  impossible  to  cut  out  all  coolers 
at  the  same  time. 

Purification  of  oil  is  effected  by  duplicate  motor 
driven  centrifugal  oil  separators,  the  oil  for  this  pur- 
pose being  withdrawn  from  the  bottom  of  the  reservoir 
lank  forming  the  suction  to  the  pumps.  By  proper  ar- 
rangement of  valves  this  purification  can  be  made  a  con- 
tinuous process,  a  part  of  the  oil  being  filtered  at  all 
times. 

Another  feature  of  the  oiling  system  is  the  emer- 
gency supply  tank,  located  considerably  above  the  tur- 
bine room  floor  and  normally  filled  with  clean  oil  from 
the  oil  separators.  In  case  of  necessity,  when  all  other 
means  fail,  a  quick  opening  gate  valve  releases  this 
supply  for  lubrication  of  the  bearings.  The  entire  oil- 
ing system  may  be  drained  into  two  storage  tanks, 
located  in  the  basement. 

STATION  WATER  SYSTEM 

Various  water  and  steam  pipes  of  a  general  nature 
constitute  a  unified  system,  as  shown  in  Fig.  11.  Four 
different  kinds  of  water  are  provided,  namely,  deepwell 
water,  raw  river  water,  condensate  from  the  main  unit, 
and  distillate  from  the  evaporators,  and  these  may  be 
interconnected  in  several  different  ways  in  order  to  in- 
sure continuous  operation  of  the  plant.  The  nonnal 
f^ow  of  water  is  as  follows: — 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  Xo.  5 


Starting  at  the  deep  well  (as  indicated  in  the  lower 
right-hand  corner),  water  is  pumped  to  a  25000  gallon 
rectangular  steel  storage  tank  on  the  roof  from  which 
water  is  taken  for  supplying  the  evaporators  as  well  as 
cooling  in  various  parts  of  the  plant.  From  the  eva- 
porators tlie  water  goes  either  direct  to  the  boiler  feed 
tank  or  to  a  large  200  000  gallon  concrete  storage  tank 
in  the  basement  of  the  building.  From  this  it  is  pumped 
to  a  condensate  head  tank,  located  directly  above  the 
boiler  feed  tank.  These  are  large  rectangular  steel 
tanks,  the  head  tank  being  of  25  000  gallon  capacity  and 
the  feed  tank  20000  gallon  capacity.  From  the  head 
tank,    water    flows    into    the    barometric     condenser, 


\dll,  therefore,  effect  the  feed  tank  first,  the  head  tank 
second  and  the  storage  tank  third. 

River  water  is  taken  from  the  main  intake  and 
pumped  to  a  21  000  gallon  raw  water  tank  on  the  roof, 
'ihe  discharge  from  this  tank  connects  into  the  deep- 
v.'ell  water  line,  so  that  in  case  of  necessity  this  can  be 
used  in  the  evaporators  and  for  all  cooling  purposes. 
This  water  is  used  mainly  for  wetting  ashes  in  the  ash 
liit  about  18  in.  above  the  clinker  grinders. 

In   addition    to    the   tank,   large   circular   blow-off 
tanks    are    provided    in    the    basement    for   any    water ' 
which  may  be  blown  out  or  drained  out  of  the  boilers, 
and  this  is  also  pumped  back  into  the  main  boiler  feed 


m..    c) — l.l.M-.KAl.   \ll-;\v    OK    MAIN   CENER.VTING   ROOM 

The  exciters  and  heat  balance  set  are  at  the  left.  The  house  turbine  is  located  in  the  alcove  at  the  right. 


located  immediately  under  it,  where  steam  from  the 
house  turbine  exhaust  is  condensed,  and  the  mixture  or 
tail  water  descends  directly  into  the  feed  tank.  This 
tail  pipe  opens  into  a  compartment  in  the  tank  from 
which  the  water  flows  over  a  V-notch  in  its  travel  to 
the  feed  pumps,  which  measures  the  amount  of  water 
passing,  and  any  excess  which  might  overflow  passes 
ever  another  set  of  V-notches  in  the  same  tank  on  its 
way  back  to  the  main  storage  tank  in  the  basement. 
The  supply  to  the  head  tank  above  is  float  operated, 
and  an  emergency  pipe  extends  from  the  head  tank  to 
the  boiler  feed  tank,  by-passing  the  condenser,  in 
which  another  float  operated  valve  is  located  and  oper- 
ated by  the  water  level  in  the  lower  tank.  Any  exces- 
sive demand  for  water  that  mav  come  on  the  station 


storage  tank  by  a  small  pump.  The  amount  of  blow- 
off  is  very  small,  but  as  the  boilers  themselves  hold  a 
large  amount  of  water  it  is  economical  to  reclaim  this 
instead  of  losing  it  when  it  is  necessary  to  take  a 
boiler  out  of  service.  All  other  drain  water,  such  as 
high  and  low-pressure  condensation  is  carefully  col- 
lected and  piped  back  to  the  proper  tank,  depeiiding  on 
its  temperature. 

A  small  vacuum  pump  is  provided  in  connection 
with  the  barometric  condenser  to  remove  as  much  of 
the  air  as  possible  to  prevent  its  passage  down  into  the 
boiler  feed  tank.  Vacuum  can  be  obtained  from  this 
pump  only,  when  conditions  will  permit  the  feed  water 
temperature  to  be  comparatively  low.  A  blanket  of 
tork  floats  rests  upon  the  entire  surface  inside  the  feed 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


203 


storage  tank  for  the  purpose  of  preventing  the  absorp- 
tion of  air. 

STATION    HEAT  BALANCE 

There  are  only  three  sources  of  exhaust  steam, 
namely,  house  turbines,  boiler  feed  pumps  and  force 
draft  fans,  all  other  auxiliaries  being  electrically  driven. 
The  exhaust  from  the  house  turbine  is  directly  con- 
nected into  the  barometric  condenser,  and  the  fans  and 
pumps  discharge  into  a  common  header  from  which  the 
sream  goes  either  to  the  evaporator  or  barometric  con- 
denser, depending  on  tlieir  respective  demands.  The 
pressure  in  this  header  however  is  maintained  constant 
by  a  specially  constructed  valve  which  allows  the  excess 
steam  from  the  evaporators  to  flow  into  the  line  to  the 
condenser,  which  is  always  maintained  at  a  somewhat 
lower  pressure.  In  case  the  feed  water  temperature  is 
up  to  normal  and  there  is  enough  auxiliary  load  to  cause 
an  excess  of  exhaust  steam  from  the  house  turbine,  this 
load  is  shifted  by  the  switchboard  operator  to  the  heat 
balance  motor  generator  set  until  the  required  equili- 
brium is  obtained,  thereby  maintaining  the  heat  balance 


s 

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oad  m  Thousandi  Kilowatts 

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FIG.     10 — GUARANTEED    W.A.TER    RATES    FOR     MAIN    GENERATOR    UNIT 

At  265  lbs.  per  sq.  in.  gage  pressure;  175  degrees  F  super- 
heat; 85  percent  power-factor. 

of  the  Station.  As  a  guide  to  the  switchboard  operator 
in  this  respect  a  long  distance  feed  water  temperature 
recorder  is  located  in  the  operator's  room.  The  level 
of  water  in  the  various  tanks  is  indicated  electrically 
en  a  board  on  the  main  turbine  room  floor,  by  which 
the  engineer  in  charge  can  tell  the  condition  of  the 
water  system  at  a  glance. 

From  the  station  wiring  diagram,  Fig.  12,  it  may 
be  seen  that  the  house  generator  feeds  into  a  bus  that 
normally  operates  at  a  somewhat  lower  frequency  than 
the  main  60  cycle  bus.  These  are  at  the  same  voltage, 
however,  and  the  motor-generator  set  known  as  the  heat 
balance  set,  is  connected  between  them.  The  motor  is 
connected  to  the  60  cycle  or  transformer  bus  and  the 
generator  to  the  57  cycle  or  house  generator  bus.  The 
house  turbine  and  heat  balance  set  are  controlled  from 
the  main  operating  gallery  the  same  as  the  main  unit. 
If  the  house  turbine  is  in  service  and  carries  the  entire 
station  auxiliary  load,  the  heat  balance  set  will  be  float- 
ing on  the  line.  If  under  this  condition  the  amount  of 
exhaust  steam  from  the  house  turbine  should  be  such 


as  to  give  a  feed  water  temperature  higher  than  is  de- 
sired, some  of  the  auxiliarj^  load  would  be  shifted  by 
the  switchboard  operator  to  this  heat  balance  set.  This 
would  cause  a  decrease  in  the  speed  of  the  induction 
motor  of  the  heat  balance  set,  and  a  slight  lowering  of 
its  generator  frequency,  and  at  full  load  on  this  set  its 
frequency  will  drop  to  about  57  cycles  as  a  minimum. 
Eventually,  each  main  60000  kw  unit  will  have  a  little 
power  system  serving  it  similar  to  this,  but  these  small 
systems  will  be  interconnected  so  that  either  the  house 
generator  or  heat  balance  set  may  be  used  as  spares  for 
the  other  main  units.  After  the  second  main  unit  is 
installed,  the  flexibility  obtained  in  this  manner  will  be  a 
decided  advantage  in  the  operation  of  the  station.  It  is 
entirely  possible,  of  course,  to  transfer  the  entire  load 
to  the  main  transformer  bus  by  means  of  the  bus  tie 
switch  shown  near  the  center  of  the  diagram,  but  this 
vvill  eliminate  the  safety  features  of  the  house  service 
system. 

EVAPORATOR 

The  vapor  from  the  evaporator  is  condensed  in  a 
small  condenser,  the  cooling  water  for  which  is  the  con- 
densate from  the  main  turbine.  Thus,  the  heat  given 
off  in  this  condenser  finds  its  way  back  to  the  boilers 
v.'ith  no  loss  in  the  evaporating  process  except  radiation 
and  a  small  amount  of  leakage  of  hot  concentrated 
water.  Fig.  13  shows  schematically  the  action  of  the 
evaporator.  This  unit,  capable  of  distilling  15  tons  of 
raw  water  per  hour,  consists  of  three  cylindrical  shells, 
two  of  which  known  as  "effects"  are  lettered  for  con- 
venience A  and  B,  the  third  being  the  surface  con- 
denser. On  the  left  hand  sketch,  the  exhaust  steam 
from  the  forced  draft  fan  turbines  and  the  boiler  feed 
pump  turbines  enter  eft'ect  B.  The  raw  water  enters 
effect  A  according  to  the  diagram,  but  in  our  practice  it 
is  admitted  into  the  hot  effect.  The  circulating  pump, 
located  immediately  below  each  effect,  raises  this  raw 
water  to  the  top  of  the  effect  and  discharges  it  in  a 
spray  over  the  tubes.  The  steam  on  the  inside  of  the 
tubes  causes  the  raw  water  to  vaporize  and  these  vapors 
pass  off  into  the  cool  effect  A.  The  operation  of  the 
second  effect  is  the  same  as  that  of  the  first,  except  that 
the  vapor  from  the  first  evaporates  more  raw  water  in 
the  second  effect.  The  resulting  vapors  pass  on  to  the 
condenser.  The  steam  which  enters  the  tubes  in  both 
effects  is  condensed,  and  the  resulting  water  flows  back 
out  of  the  tubes  into  traps  in  the  steam  end  of  each 
effect.  This  water  from  both  effects  flows  together  into 
a  flush  chamber  where  it  bursts  into  steam  which  then 
enters  the  condenser. 

The  right  hand  sketch  shows  the  operation  of  this 
unit  after  "reversing".  In  this  sketch  the  exhaust  steam 
enters  A,  B  now  being  the  cold  effect.  Reversing  the 
operation  of  the  evaporator  causes  a  change  in  tempera- 
ture of  each  effect  which,  due  to  the  resulting  expan- 
sion, tends  to  crack  off  any  scale  that  might  have 
formed.  The  scale  is  then  precipitated  and  is  carried 
away  through  a  residual  water  connection. 


204 


THE  ELECTRIC  JOURNAL 


\oI.  X\III,  Xo.  5 


CONDENSERS 

Each  main  unit  has  looooo  sq.  ft.  of  condensing 
surface  contained  in  four  shells,  one  for  each  of  the 
low-pressure  exhausts.  Each  shell  is  further  sub- 
divided in  two  sections  so  that  one-eighth  of  the  total 
surface  may  be  isolated  for  cleaning.  This  has  proven 
to  be  of  advantage  where  a  large  quantity  of  leaves 
bank  against  the  revolving  screens  and  some  find  their 
way  into  the  condensers. 

The  tubes  in  these  condensers  are  somewhat  special 
in  that  they  are  expanded  into  the  tube  sheet  on  one 
end  and  pass  through  the  other  end  through  the  ordi- 
nary packing  box.  The  tubes  are  supported  at  the 
center  only  and  raised  slightly  at  this  point.  There  is 
considerable  sand  in  the  circulating  water  which,  up  to 
the  present  time,  has  had  a  tendency  to  polish  the  tubes. 


These  pumps  are  rated  at  44000  gallons  per  minute 
and  operate  at  480  r.p.m.  The  pump  suction  and  dis- 
charge valves,  72  in.  and  63  in.  respectively,  together 
with  inlet  valves  to  each  of  the  condenser  sections,  are 
hydraulically  operated  by  water  from  the  boiler  feed 
lines.  The  waste  water  from  these  operating  cylinders, 
together  with  the  various  overflows  and  drains  from 
gland  water  seals,  etc.,  is  collected  and  delivered  back 
to  the  system  by  means  of  a  small  float-operated  con- 
densate reclaiming  pump. 

CONDENSATE  PUMPS 

There  are  installed  four  motor-driven  two-stage 
condensate  pumps.  With  maximum  load  on  the  unit, 
only  two  of  these  pumps  are  requii'ed.  The  others 
serve  as  spares.  An  emergency  connection  has  been 
provided  so  that,  in  cases  of  extreme  contamination,  the 


CondenKlte 
Head  Tank  No.  1 
25  500  Gal    Cap. 


Condensate 

Head  Tank  No.  2 

25  500  Gal.  Cap 


IBaromet 
Condense 
I     No.  2 


li 


I 1 14  In.  Matn  Condensate  Pipe 


Deep 

Well 


— ^"^  Exhaust  Stean- 
—'—  Condensate 

Boiler  Feed 

Well  Water 

Raw  Water 


FIG.    II— FEED  WATER  FLOW  DIAGRAM 

Tlie  temperatures  on  the  diagram  correspond    approximately  to  the  temperatures  in  the  various 

parts  of  the  system  during  normal  operation. 


Valves  on  the  discharge  from  each  condenser  sec- 
tion are  motor  operated.  Any  degree  of  regulation  of 
the  quantity  of  cooling  water  can  thus  be  obtained.  As 
a  further  means  of  regulating  condenser  temperatures 
a  gate  may  be  opened,  permitting  the  discharge  circu- 
lating water  to  be  recirculated  through  the  condensers. 

The  guarantee  performance  of  these  units  is  shown 
in  Fig.  15  and  their  preliminary  operation  seems  to  in- 
dicate that  their  performance  under  full  load  will  ap- 
proximate these  values. 

CIRCULATING  PUMPS 

For  each  unit,  three  centrifugal  motor-driven 
pumps  are  provided  discharging  into  a  60  inch  common 
header  so  that  any  pump  or  combination  of  pumps  may 
be  used  to  supply  circulating  water  to  the  condensers. 


water  from  the  condensate  pumps  may  be  discharged 
to  the  river. 

AIR  PUMPS 

Three  Leblanc  air  pumps  are  installed  for  air  re- 
moval purposes.  These  pumps  receive  their  hurling 
water  from  and  discharge  into  two  concrete  tanks  be- 
low the  basement  floor.  The  supply  of  cold  water  is 
obtained  through  a  hand-regulated  valve  fitted  with 
twin  strainers  and  connected  to  the  discharge  header  of 
the  circulating  pumps.  The  overflow  from  these  tanks 
flows  into  another  concrete  tank  from  which  it  is  re- 
moved by  means  of  two  float-controlled,  electrically- 
driven  removal  pumps.  It  is  planned  to  install  a  rota- 
tive dry  vacuum  pump  in  connection  with  an  .•  bell 
for  the  purpose  of  measuring  the  air  leakage. 


May,   1921 


THE  ELECTRIC  JOURNAL 


205 


FORCED  DRAFT  FANS 

The  fans  are  of  the  horizontal  double  inlet  type, 
delivering  250  000  cu.  ft.  per  minute.  They  are  driven 
at  variable  speed  by  steam  turbines  through  reduction 
gears,  and  are  controlled  from  the  station  steam  pres- 
sure by  means  of  regulators.  Each  fan  unit  is  capable 
of  supplying  air  for  40  000  kw  of  load  continuously,  and 
three  fans  are  provided  for  120000  kvv  of  turbine  ca- 
pacity. 

There  is  a  definite  path  of  air  through  the  station 
as  follows : — Openings  are  provided  in  the  building  wall 
oi)  the  river  side  and  covered  with  metal  curtains  in 
such  manner  that  air  to  the  air  washers  can  be  obtained 
from  the  outside,  inside  or  both  at  the  same  time.  The 
air  path  is  a  closed  circuit  from  the  washers  to  the  gen- 
erators, but  the  passages  are  large  and  contain  the  main 
generator  leads.  The  path  through  the  generator  is  up 
through  the  end  bells  along  the  air-gap  through  the 
stator  and  down  into  another  duct  leading  to  the  forced 
draft  fan  room.     This   fan   room   is   inclosed  on   three 


nections  from  the  main  generators  to  the  main  step-up 
transformers  are  of  bus  construction  or  its  equivalent, 
thereby  reducing  the  chances  of  a  short-circuit  to  a 
minimum.  All  busses  are  in  duplicate.  The  main 
12  000  volt  busses  are  mounted  in  rooms  separated  by  a 
fire-proof  structure,  as  shown  in  Fig.  19.  The  station 
service  busses  are  sufficiently  separated  to  prevent 
trouble  on  one  bus  from  spreading  to  the  adjacent 
busses. 

GENERATORS 

The  three  generators  of  the  unit  are  each  rated  at 
20000  kw  at  85  percent  power- factor,  12000  volts. 
They  are  normally  operated  as  a  single  unit,  being 
brought  up  to  operating  frequency  and  voltage  in  syn- 
chronism, with  the  fields  excited,  steam  being  supplied 
to  the  high-pressure  cylinder  only.  They  are  normally 
synchronized  with  the  66000  volt  system  by  means  of 
the  circuit  breaker  between  the  12000  volt  bus  and  the 
main  transformer  bank. 

On    the    revolving    fields    of    each 


generator    are 


l:^:*^ 


mMMM 


jj  jjjjjjj  III  jj'ij.i  I J 1 1 1 


mm 

66i6i  "   ' 


^ 


JJJJJJjJj  I  I  ' 


^^^^^ 


mmm 


6 


YYY 


FIG.    12— SCHEMATIC  DI.AGRAM   OF  MAIN  AND  AUXILIARY  BUSSES 

sides  only,  the  open  side  connecting  into  the  ash  cellar,      mounted    fan    blades    whici 


From  the  forced  draft  fan  the  air  path  is  completed  to 
the  top  of  the  stack. 

ELECTRICAL  EQUIPMENT 

The  electrical  end  of  Colfax  power  station  has  been 
so  designed  that  each  60  000  kw  generating  unit  will  be 
entirely  separate  and  isolated  from  the  other  units. 
Each  unit  comprises  three  main  generators;  a  station 
service  generator;  a  bank  of  step-up  transformers;  a 
bank  of  station  service  transformers;  one  exciter;  and 
one  heat  balance  motor-generator  set;  with  the  neces- 
sary bus  structures  and  control  boards.  The  only  inter- 
connection to  be  made  between  units  will  be  on  the 
66  000  volt  busses,  which  supply  the  out-going  feeders. 
As  the  reactance  of  the  main  transformers  is  included 
in  the  circuit  between  the  generators  and  the  busses  on 
khich  the  generators  are  paralleled,  there  is  no  need  for 


draw    air    from    the    air 
he  generator  laminations 


washer,   forcing  it   through 

and  windings.  After  passing  through  the  generators, 
the  heated  air  is  used  for  forced  draft  purposes  in  the 
boiler  room,  thereby  resulting  in  more  economical  op- 
eration. 

Each  generator  is  protected  with  differential  re- 
lays so  that  in  case  of  internal  grounds  or  short-circuits 
in  the  windings  or  leads  to  the  12  000  volt  bus,  it  will 
immediately  be  disconnected  from  service,  the  field  cir- 
cuit breaker  ana  the  over-speed  device  of  the  steam  tur- 
bine being  tripped,  so  as  to  minimize  the  damage  that 
might  result  from  such  occurrence.  In  addition  to  this 
protection,  steam  connections  are  made  to  perforated 
pipes  beneath  the  generator  windings,  so  that  in  case  of 
fire,  steam  can  be  turned  into  the  generator  casing  to 
smother  the  flames.     At  the  same  time  dampers  in  the 


bus-bar  reactors.     This  arrangement  greatly  simplifies      ^'^  ^"'^^^   '^^^  ^^  closed  by  remote   control   from   the 


the  wiring,  reduces  the  number  of  circuit  breakers  and 
minimizes  the  possibility  of  trouble.  It  is  made  possible 
by  the  location  of  the  station  at  a  point  where  there  is 
little  local  load,  so  that  normally  the  entire  station  out- 
put is  transmitted  at  66  000  volts.     All  12  000  volt  con- 


switchboard,  effectively  smothering  the  flames. 

Each  generator  element  has  a  ground  connection 
from  the  neutral  of  the  star  through  a  resistance,  rated 
at  seven  ohms  and  1000  amperes  for  two  minutes,  and  a 
circuit  breaker  with  disconnecting  switches.     A  signal 


206 


THE  ELECTRIC  JOURNAL 


Vol.- XVIII,  No. 


lamp  and  alarm  bell  in  the  control  room  are  connected 
to  a  current  transformer  in  each  generator  ground  cir- 
cuit beyond  the  star  connection,  to  notify  the  station 
operator  when  a  ground  has  occurred.  Only  one  of  the 
generators  is  normally  grounded  at  a  time,  in  order  to 
avoid  circulating  currents,  and  the  circuit  breakers  in 


FIG.    13 — FLOW    DI.\r,R.'\M    OF    STE.\M    ANIl    WATER  THROUGH    THE 
EVAPORATORS 

the  ground  circuit  are  so  interconnected  that  the  closing 
of  any  one  will  automatically  trip  out  any  other  that  is 
closed. 

The  leads  from  each  generator  element  are  pro- 
vided with  eight  1600-5  ampere  current  transformers  of 
the  through  type,  which  furnish  current  to  three  alter- 
nating-current ammeters  (0-1600)  ;  one  polyphase  watt- 
laeter  (0-30000  kw)  ;  one  direct-current  field  voltmeter 
(0-300)  which  also  has  a  scale  in  red  which  indicates 
amperes  when  the  fields  are  at  normal  operating  tem- 
perature; one  polyphase  wattmeter  type  differential  re- 
lay; one  polyphase  watthour  meter.  For  taking  in- 
ternal temperatures  of  the  generators,  six  resistance 
coils  and  six  thermocouples  are  mounted  in  the  slots  of 
each  armature  and  connections  are  made  to  a  potentio- 
meter in  the  control  gallery. 

The  leads  from  the  generators  to  the  12  000  volt 
bus  room  consist  of  two  i  000  000  circ.  mil  cables  for 
each  generator  phase.  These  cables  are  insulated  with 
varnished  cambric  with  a  braided  covering  for  15000 
volts  and,  as  an  additional  factor  of  safety,  are  mounted 
on  25  000  volt  duplex  porcelain  insulators.  For  con- 
venience they  are  carried  under  the  floor  in  the  genera- 
tor air  ducts. 

The  main  switchboard  in  the  control  room  is  shown 
in  Fig.  16.  The  control  desk  has  seven  sections,  which 
are,  from  front  to  back : — exciter  and  Tirrill  regulator ; 
bouse  turbine  and  transfer  switches;  heat  balance;  sta- 
tion transformers ;  main  transformers ;  main  genera- 
tors; face  plate  regulators.  The  instrument  panels  are 
mounted  directly  behind  the  corresponding  panels  on 
the  control  desk.  The  high-tension  feeder  board  is  at 
the  rear  of  the  control  desk.  The  battery  board  from 
which  all  direct-current  control  circuits  are  manipulated 
is  at  the  right,  and  in  the  foreground  at  the  right  is  the 
potentiometer  pedestal  for  the  generators  with  a  switch- 
board type  potentiometer  calibrated  in  degrees  C.  and  a 


group  of  revolving  dial  switches  for  connecting  the 
thermocouples  to  the  potentiometer.  Mounted  on  this 
same  pedestal  is  the  control  for  a  large  illuminated  sign 
mounted  in  the  boiler  room,  by  means  of  which  the 
switchboard  operator  can  signal  the  load  in  kw  that  is 
being  carried  or  that  is  expected.  A  telephone  switch- 
board gives  immediate  access  to  all  parts  of  the  plant 
and  a  loud  speaker  permits  the  operator  to  talk  without 
the  use  of  a  head  set.  The  one  shown  in  Fig.  16  is 
duplicated  with  a  parallel  equipment,  so  that  connec- 
tions between  points  in  the  plant  or  to  the  outside  can 
be  made  without  disturbing  the  switchboard  operator. 

A  duplicate  system  of  voltage  control  is  installed. 
Principal  reliance  is  placed  upon  a  face  plate  regu- 
lator, which  consists  of  a  large  high-speed  motor-oper- 
ated rheostat  mounted  in  the  main  field  circuit  of  each 
generator.  These  rheostats  are  actuated  through  a 
group  of  control  coils  by  a  balance  between  the  exciter 
voltage  and  the  voltage  of  the  main  generator,  in  much 
the  same  manner  as  is  done  in  a  Tirrill  regulator.  To 
prevent  over-shooting,  they  are  arranged  to  advance  by 
small  steps,  which  are  quickly  repeated  until  the  de- 
sired voltage  is  maintained.  As  the  face  plate  regula- 
tor influences  the  fields  of  the  generator  directly,  it 
eliminates  the  time  lag  which  is  inherent  in  regulating 
the  field  of  the  exciter.  Also  in  case  the  contacts  stick 
there  is  not  produced  the  extreme  fluctuation  in  voltage, 
which  occurs  with  the  Tirrill  regulator.  As  an  auxil- 
iary system  of  voltage  control,  a  standard  Tirrill  regu- 
lator is  provided  which  operates  on  the  exciters  in  the 
usual  way.  A  Tirrill  regulator  is  also  provided  for  the 
house  turbine  and  heat  balance  generator. 


FIG.    14 — PAIR  OF  MAIN  COMDENSERS 

Showing  also  the  circulating  water  piping  and  the  hydrauli- 
cally-operatcd  gate  valves. 

An  induction  regulator  type  signal  system  is  in- 
stalled for  transmitting  signals  between  the  control 
room  and  the  gage  boards  near  the  main  turbine.  The 
transmitter  consists  of  a  small  induction  regulator  with 
u  three-phase  wound  rotor  connected  to  a  standard  60 
cycle  source  of  supply,  and  a  single-phase  stator  which 


May,  1 92 1 


THE  ELECTRIC  JOURNAL 


207 


is  connected  to  duplicate  position  indicators,  one  at  each 
station.  The  position  indicator  is  a  standard  power- 
factor  meter  whose  dial  is  marked  with  the  signals  de- 
sired instead  of  the  usual  power-factor  scale.  As  both 
position  indicator  needles  follow  closely  the  position  of 
the  transmitter,  any  desired  signal  can  be  given.  The 
signal  is  answered  by  replying  with  the  same  signal  on  a 
similar  equipment,  operated  from  the  turbine  gage 
board.  A  push  button  signal  is  also  used  to  call  the  at- 
tention of  the  operator  to  the  signal  indicator,  which 
sounds  an  air  whistle  and  lights  a  signal  lamp  in  the 
turbine  room  or  sounds  a  buzzer  and  lights  a  lamp  in 
the  control  room. 

EXCITATION    SYSTEM 

For  each  60  000  kw  unit  there  is  one  350  kw  shunt 
wound  exciter.  This  exciter  is  duplex  driven  from  an 
induction  motor  and  a  direct-connected  turbine.  Nor 
mally,  the  generator  will  be  driven  from  the  motor  end, 
with  a  small  amount  of  live  steam  bled  into  the  turbine 
through  the  governor;  if,  in  case  of  trouble,  the  speed 
of  the  set  should  fall  below  nonnal,  the  steam  turbine 
automatically  picks  up  the  load.  In  addition  to  this 
exciter,  there  is  a  duplicate  exciter  which  will  be  used 
as  a  spare  for  all  units. 

MAIN  TRANSFORMERS 

The  main  step-up  transfonners  consist  of  three 
23  600  kv-a  water  cooled  transformers.  They  are  con- 
nected delta  on  the  primary  side  and  star  on  the  second- 
ary. These  transformers,  like  all  the  other 
high-voltage  apparatus  in  the  station,  are  designed 
to  operate  at  132  000  volts,  and  are  the  largest  single- 
phase  transformers  built  by  the  Westinghouse  Company 
to  date.  Differential  relays  are  so  connected  that,  in 
C2se  of  grounds  or  short-circuits  either  in  the  trans- 
formers or  the  connections  to-  them,  they  will  be  discon- 
nected from  service  immediately.  A  fourth  trans- 
former of  the  same  capacity  is  mounted  adjacent  to  the 
others  and  can  readily  replace  any  of  them  in  case  of 
trouble.  The  spare  transformer  is  connected  to  the 
])iping  system  for  water  cooling  and  is  arranged  for 
quick  connection  in  place  of  any  of  the  others  by  means 
of  removable  pipe  links  on  the  high-voltage  side  and  dis- 
connecting switches  on  the  low-voltage  side.  The  trans- 
formers are  mounted  on  rails,  and  doors  are  provided 
so  that  any  of  the  transformer  units  can  be  run  into  the 
turbine  room  where  the  station  crane  is  available  for 
repairs. 

The  high-voltage  neutral  of  the  transformer  bank 
is  grounded  through  a  resistance  of  95  ohms.  A  cur- 
rent transformer  is  connected  in  the  ground  circuit, 
which  actuates  an  alarm  bell  and  a  signal  lamp  in  the 
control  room  and  is  also  connected  to  a  graphic  meter. 

HIGH-TENSION  BUSSES 

Comparative  designs  showed  that  in  this  particular 
station  it  would  be  cheaper  to  place  the  high-tension 
transformers  and  circuit  breakers  indoors  rather  than 
outdoors.     Inasmuch  as  the  standard  outdoor  spacings 


of  bus-bars  has  been  secured  in  this  interior  installation, 
it  is 'also  considered  that  the  reliability  of  operation  is 
improved,  and  any  repairs  can  be  effected  more  easily. 
The  general  arrangement  of  the  indoor  132000  volt 
structure  is  shown  in  Figs.  5  and  17.  The  disconnect- 
ing switches  between  the  transformers  and  circuit 
breakers  are  of  the  gang  operated,  three  pillar  rotating 
type,  manipulated  from  the  floor  by  handles  which  are 
normally  kept  locked.  The  leads  from  the  indoor 
T32  000  volt  circuit  breaker  pass  directly  up  to  duplicate 
high-tension  busses  on  the  roof  through  high-tension 
wells  as  shown  in  Figs.  5  and  18. 

CIRCUIT   BREAKERS 

All  of  the  oil  circuit  breakers  are  of  the  remote- 
control  solenoid-operated  type.  As  shown  in  Fig.  19, 
the  main   12  000  volt  oil  circuit  breakers  are  mounted 


—29.40 


29.2Q 
■3-2900 
■5-28.80 

28.60 


Guaranteed  Vacua  referred  I 

;  Uitit  is  supplied  with 
-28-20J — '^^    '"*  .*3ri    88  000    G.P.M.    Circulating. 
i^Air  Leakage  not  exceeding 


Inlet  Circ  jlatin  ;  Wa  er  T^mpei 


Guaranteed  Vacua  referred  to  a  30  inch  Baro- 
meter when  Condensing  Unit  is  supplied  with 
i.P.M.    Circulating 


T 

rculatin 


0.60-g 
Sfro- 


r 


1.40-1 

C 

1.60-5 


FIG.  15 — GUARANTEED  CONDENSER  PERFORMANCE 

For  100  000  sq.  ft.  surface  condensers, 
adjacent  to  the  12000  volt  bus  chamber.  The  132000 
volt  oil  circuit  breakers  between  the  main  transformers 
and  the  66000  volt  busses  are  mounted  on  the  main 
floor  of  the  electrical  bay.  When  actuated  by  instan- 
taneous relays  these  circuit  breakers  are  capable  of  rup- 
turing 12400  r.m.s.  amperes  per  phase  at  66000  volts. 
The  2200  volt  circuit  breakers  for  the  auxiliaries 
are  mounted  in  cells,  as  shown  in  Fig.  20.  All  these 
circuit  breakers  are  provided  with  red  and  green  lights 
at  the  circuit  breaker  as  well  as  on  the  switchboard,  to 
mdicate  whether  they  are  open  or  closed.  In  addition 
a  small  double-pole  push-button  switch  is  mounted  just 
above  the  circuit  breaker,  which  interrupts  the  control 
circuit,  preventing  the  operation  of  the  circuit  breaker. 
This  switch  also  serves  to  light  a  white  lamp  if  the  cir- 
cuit breaker  is  in  the  open  position,  but  a  pallet  switch 
en  the  circuit  breaker  prevents  the  lighting  of  the  white 


THE   ELECTRIC  JOURNAL 


Vol.  X\'III,  No.  5 


lamp  if  the  circuit  breaker  is  closed.  This  arrangement 
provides  an  additional  source  of  safety  to  anyone  de- 
siring to  work  on  the  circuit  breaker  or  operate  the  dis- 
connecting switches. 

STATION   SERVICE 

As  the  majority  of  the  auxiliaries  are  electrically 
driven,  duplicate  sources  of  power  supply  have  been 
provided,  as  shown  in  Fig.  12,  viz.,  either  from  the  main 
generators  or  the  house  generator.  All  motors  over  100 
hp  are  operated  at  2200  volts,  while  the  smaller  ones 
operate  at  440  volts.  Being  located,  so  close  to  a  very 
large  source  of  power  supply,  all  the  2200  volt  motors 
have  their  main  connections  made  through  oil  circuit 
breakers.  The  600  hp  circulating  pump  and  100  hp 
compressor  motors  are  of  the  wound-secondary  type 
and  these  are  started  by  drum  controllers  mounted  be- 
side   the    motors.       The    secondary    connections    are 


without  first  connecting  it  to  the  starting  position,  and 
it  is  also  impossible  to  connect  it  to  both  positions 
smiultaneously. 

The  adjustable-speed  stoker  and  clinker  grinder 
motors  receive  their  supply  from  250  volt  direct-current 
motor-generator  sets,  which  are  in  duplicate. 

HEAT  BALANCE   MOTOR-GENERATOR  SET 

As  the  exhaust  from  the  house  turbine  is  used  for 
heating  the  feed  water,  it  is  necessary  to  vary  the  load 
on  this  unit,  in  order  to  maintain  a  constant  tempera- 
ture. This  is  accomplished  by  transferring  the  load 
from  the  house  generator  to  the  main  generators  or 
vice-versa.  In  order  to  provide  closer  adjustment  than 
could  be  obtained  by  paralleling  the  house  generator 
directly  with  the  main  generators,  a  motor-generator  set 
consisting  of  a  synchronous  generator  driven  by  an  in- 
duction motor  is  connected  between  the  two  systems,  as 


FIG.   16 — MAIN  SWITCHBO.\RD  AND  CONTROL  ROOM 

The  instrument  board  and  control  desk  are  at  the  left;  thehigh  tension  feeder  board  is  at  the  rear  of  the  room;  the  baUery 
and  direct-current  control  board  is  at  ihe  right;  and  the  potentiometer  pedestal  is  in  the  right  foreground.  The  telephone 
switchboard  gives  instant  communication  with  all  parts  of  the  plant. 


handled  by  the  drum  directly,  but  the  primary  connec- 
tions are  remote  control  through  a  contact  on  the  drum. 
The  heat  balance  motor  and  the  exciter  motors,  which 
are  also  of  the  wound-secondary  type,  are  arranged  for 
unit  switch  automatic  acceleration,  the  exciter  motors 
being  started  from  push  button,  stations  near  the  units, 
while  the  heat  balance  motor  is  started  from  the  main 
switchboard. 

All  other  auxiliary  induction  motors  are  of  the 
squirrel-cage  type.  They  are  started  from  a  low-volt- 
age bus  as  shown  in  Fig.  12,  through  oil  circuit 
breakers,  which  are  actuated  by  push  button  control 
alongside  the  motor,  each  push  button  station  having 
three  positions  marked  Start,  Run  and  Stop.  The  cir- 
cuit breakers  for  connecting  these  motors  to  the  start- 
ing and  running  positions  are  interlocked  electrically 
and  are  provided  with  sequence  relays  so  that  it  is  im- 
possible  to    connect    a   motor   to   the   running   position 


shown  in  Fig.  12.  The  governor  of  the  house  turbine 
is  controlled  by  a  motor  actuated  from  the  switchboard 
so  as  to  give  any  desired  speed  between  57  and  60 
cycles.  When  more  steam  is  needed  from  the  house 
turbine  to  raise  the  feed-water  temperature,  as  indicated 
by  a  feed-water  graphic  thermometer  located  on  the  in- 
strument board,  its  speed  is  increased  so  that  it  carries  a 
larger  percentage  of  the  auxiliary  load  and  the  heat  bal- 
ance generator  a  smaller  percentage.  The  load  carried 
by  the  heat  balance  generator  is  obviously  proportional 
to  the  difference  in  frequencies  between  the  bus  bars,  as 
the  heat  balance  motor  will  carr\'  no  load  when  the  two 
bus-bars  are  operating  at  the  same  frequencies.  This 
set  is  protected  with  relays  that  automatically  discon- 
nect it  from  service,  thereby  separating  the  two  systems, 
in  the  event  of  shutting  down  the  main  unit,  or  other 
disturbances  that  would  cause  a  large  difference  in  fre- 
quency between  the  two  systems. 


May,  1 92 1 


THE   ELECTRIC  JOURNAL 


209 


The  heat  balance  motor-generator  set  provides  a 
system  of  controlHng  the  heat  balance  of  the  station 
which  is  at  once  flexible  and  sensitive.  This  arrange- 
ment also  requires  that  any  disturbance  on  the  main 
bus-bars  must  be  serious  enough  to  produce  a  decrease 
in  frequency  of  approximately  five  percent  before  the 
house  turbine  is  separated  from  the  main  bus  bars, 
which  is  a  great  advantage  over  any  system  which  re- 
quires that  these  units  be  disconnected  with  any  de- 
crease in  main  bus-bar  frequency. 

It  will  be  seen  from  Fig.  12  that,  if  the  disconnect- 
ing switches  between  the  60  cycle  and  57  cycle,  2200 
volt  busses  and  the  auxiliary  circuit  breakers  were 
closed  simultaneously,  the  house  generator  would  be 
connected  with  the  main  generators  out  of  synchronism. 
To  prevent  this,  these  busses  and  disconnecting  switches 
are  mounted  back  to  back  on  opposite  sides  of  the  same 
wall,  and  a  rod  running  through  this  wall,  in  guides 
serves  as  a  mechanical  interlock,  to  ])revent  these  dis- 
connecting  switches    being   closed    simultaneously.      A 


KIG.    I- — 132  000  VOLT   BUS   STRUCTURE   IX   THE  TRA.VSFOKMER   ROOM 

bus-tie  circuit  breaker  is  provided,  however,  to  tie  these 
two  busses  together  if  the  house  turbine  is  shut  down 
or  if,  for  any  reason,  it  is  desired  to  synchronize  it  with 
the  main  unit. 

CONTROL  SYSTEMS 

.Ml  the  oil  circuit  breakers  and  relays  are  operated 
by  direct  current,  supplied  by  two  motor-driven  com- 
pound-wound generators  and  two  batteries,  which  are 
connected  to  a  double  bus  structure  located  in  the  con- 
trol gallery.  With  the  switching  arrangement  pro- 
vided, it  is  possible  to  charge  and  discharge  the  batteries 
v.ithout  varying  the  control  voltage;  further,  isolation 
of  grounded  control  circuits  from  the  regular  control 
system  is  also  permitted.  Trip  coil  supervision  is  ob- 
tc-.ined  by  connecting  a  red  pilot  lamp  in  series  with  the 
trip  cod.  A  resistance  is  connected  in  the  pilot  lamp 
circuit  to  prevent  a  large  flow  of  current  in  case  of  a 
pilot  lamp  or  its  fixtures  short-circuiting.  All  control 
cables  throughout  the  station  are  properly  tagged  to 
assist  the  maintenance  men  in  locating  trouble. 

'  ■'■>  ARCHITECTURAL  FEATURES 

The  building  proper  is  of  red  brick  exterior,  and 
light  brick  interior,  with  white  face  brick  wainscoting. 


slate  baseboard  and  red  tile  floor.  The  steel  stacT<s  are 
supported  from  the  building  structure  and  from  special 
steel  reinforcing  built  from  the  ground.  The  windows 
are  of  translucent  glass  in  steel  frames  and  all  louvre 
v  indows  are  niotnr  operated.     The  interior  finish  varies 


1  IG.    IS — IJJ  000  VOLT  DOUBLE  IIUS   STRUCTURE  ON  THE  ROOF  OF  THE 
POWER  STATION 

The  high  tension  wells  from  the  oil  circuit  breakers  appear 
at  the  left. 

from  white  to  black  through  a  series  of  grey  colors. 
Some  small  offices  are  of  the  lighter  colors,  while  the 
main  bulk  of  the  mechanical  equipment  is  of  medium 
grey.  No  color  distinctions  are  made  in  piping,  these 
being  distinguished  by  stenciling. 

The  station  is  built  close  to  the  Allegheny  River, 
with  the  Conemaugh  Division  lines  of  the  Pennsylvania 
Railroad  immediately  on  the  other  side.  It  is  in  open 
country  surrounded  by  desirable  residential  boroughs. 
The  substructure  of  the  building  is  a  slab  of  concrete 
9  ft.  thick,  thoroughly  water-proofed,  and  with  the  nec- 
essary tunnels,  tanks  and  sumps  provided  in  the  con- 
crete for  the  main  unit  auxiliaries.  Standard  gage 
tracks  for  the  removal  of  ash  and  machinery  are  on 
the  main  floor  elevation. 

Space  has  been  provided  on  the  ground  floor  ele- 
vation underneath  the  boiler  room  for  a  machine  shop 


FIG.    It) — M.M.X    I_>  000  VOLT  CIKCUIT   BRE.'VKERS   AND  BUS   STRUCTURE 

and  storage  of  heavy  parts.  This  space  is  inclosed  by 
solid  tile  partitions  to  keep  out  moisture  from  the  ash 
cellars  on  each  side  and  is  supplied  with  forced  venti- 
lation from  the  main  air  ducts  overhead. 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


Absolute     fireproof     construction     is     maintained  by    the    switchboard   operator   on    a    duphcate    control 

throughout  the  building,  windows,  doors,  office  furni-  board  at  night.     A  repair  room  for  small  electrical  re- 

ture,  lockers,and  cupboards  being  of  fireproof  construe-  pairs  and  instrument  work  is  provided  on  this  floor, 

tion.     A  sea  wall  on  the  river  front  is  provided  for,  and  near  the  main  control  room,  also  the  battery  room,  con- 

a  spacious  yard  on  either  side  is  at  present  being  filled  ference  room,  ladies  rest  room,  toilet  and  locker  rooms, 

in  and  leveled  off  to  improve  the  general  appearance.  ^.q^l  supply 

There  is  an  architectural  distinction  to  the  plant  .  ,         ,    ,            , 

,     ,      ,               ,     ■   ,         J    •   ^        1                              Tu„  A  special  track  for  coal  supply  enters  overhead  at 

both    form    external    and    internal    appearance.      The  ,      ,    .,                  „         ,       ,       , 

.     ,  ,         ^     r        ■         -^           ,            J  r         .1  the  boiler  room  floor  level.     A  gantry  crane  is  to  be 

svmmetncal  lavout  of  main  units  as  observed  from  the  ....            .             ,  ■             ,   , 

made  use  of  in  the  future  for  stocking  coal,  but  for  the 

present  a  stock  of  coal  in  the  yard  is  handled  by  a  loco- 
motive boom  crane.  This  coal  is  piled  to  a  maximum 
height  of  about  15  feet  to  prevent  overheating  and  igni- 
tion. The  plant  is  located  about  a  mile  from  the  mine 
shaft  which  will  supply  coal  throughout  its  contem- 
plated existence.  The  extent  of  this  field  owned  by  the 
Company  is  shown  on  the  map  in  Mr.  Stone's  article. 
Coal  Tower  Space — The  space  occupied  by  the  coal 
tower  is  utilized  to  house  the  cafeteria,  sleeping  quar- 
ters, store-room  and  time-keeping  office  on  dilferent 
e'evations.  The  noise  from  the  operation  of  the  coal 
elevator  is  heard  during  a  part  of  the  day  only,  and  any 
coal  dust  which  might  be  expected  around  macTiinery 
of  this  kind  is  carefully  avoided  by  the  generous  use 
of  solid  walls  to  completely  isolate  all  dust.  Automatic 
elevators  give  easy  access  to  these  quarters,  which  ate 
arranged  vertically,  one  above  another,  with  the  time- 
keeping and  watchman's  office  on  the  first  floor. 

STATION  PERSONNEL 

A  chief  engineer  and  three  assistants  in  charge  of 
the  boiler  room,  turbine  room  and  electrical  equipment 
respectively,  constitute  the  supervisory  operating  force. 
.•\bout  fifty  operating  men  and  thirty  maintenance  men 
will  complete  the  regular  force  when  the  first  unit  is 


•s 

!                                       ■    ,               '               ' 

FK;     jit      j_1.11    Vi.l   1    I  ll;>  I    1;     |;KEAKER   AND   BUS   COMPARTMENTS   FOR 
STATION  AUXILIARIES 

upper  balconies,  the  height  of  the  turbine  room  as  ob- 
served from  the  main  floor,  the  ornamental  lighting  and 
main  crane  constitute  a  view  that  is  imposing.  From 
the  simple  standpoint  of  magnificence  it  has  an  appeal 
to  those  who  delight  in  seeing  any  structure  so  well  built 
as  to  defy  the  ravages  of  time  and  decay. 

Locker  Rooms — On  account  of  the  magnitude  of 
the  plant,  locker  rooms,  shower  baths  and  toilet  rooms 
are  conveniently  located  on  several  different  elevations 
for  the  use  of  the  nearest  group  of  operators.     It  is  be- 


TABLK  I— GENERATING  CAPACITY  OF  DUQUESNE  LIGHT    COMPANY    POWER    STATIONS 


Power   Station 

No.  of 
Electric 
Units 

Rated 

Capacity 

Each 

1 
Tyiie                A.  C. 

1    Total 
1    Rated 
Generat- 
D.  C.            ing 

Capacity 
(Kw.) 

Number 

of  Boiler 

Units 

Rated 

Capacity 

Each 

(Hp.) 

Total  Rated 

Boiler 

Capacity 

(Hp.) 

Brunot    Island     

Colfax     

1 
.5 
1 

■    1 

a  000 

15  300 
40  000 

60  000 

1  500 

3  000 

750 

500 

H.  P.  Turbine      1 

H.  P.  Turbine          119  500 

H.  P.  Turbine      ' 

H.  P.  Turbine      |     60  000 

19 

119  500              10 

1             7 

1          20 

60  000   1            7 

500 
600 
822 
822 
2088 
300 
686 

37  694 
14  616 

2 

1 
5 
4 

L.  P.  Turbine       1 

L.  P.  Turbine       1 

P.  1.  W.  EnginesI        9  750 

P.  I.  W.  EnginesI 

2  000 

11750 

18 
2 

6  772 

Thirteenth    St 

1        1        8  000 
1         1        1  500 

1 

•        1 

H.  P.  Turbine      1        8  000 
R.  &  S.  Engines  1 

1500 
6  400 

1             2 
9  500  1            6 

1             2 

1           12 
6  400   1          16 

1             2 

350 
350 
250 
250 

6  300 

8        1            800 

1 

P.  I.  W.  EnginesI 

375                 1 

400 

Glenwood    I       1        1       2  000 

1        2        1            900 

1        4        1            500 

1                  1 

H.  P.  Turbine 

R.  &  S.  Engines           3  800 

Green  Engines 

2  000 

5  800 

2 
4 
2 
3 

375 
400 
325 
300 

3_900_ 

37 

:   201  050   1      11  900 

212  950 

134 

lieved  that  this  offers  considerable  advantage  over  any 
centralization  of  these  features. 

Station  Offices — A  large  space  is  provided  on  the 
upper  floor  over  the  electrical  bay  for  the  general  sta- 
tion offices,  reached  by  an  independent  elevator.  On 
this  floor  is  also  the  station  telephone  exchange,  which 
is  attended  by  a  special  operator  during  the  day  and 


running  at   full   capacity  and   all   equipment  has  been 
ti.ken  over. 

In  order  to  carrv-  on  tests,  special  investigations, 
time  studies  and  general  power  station  betterment,  about 
six  men,  known  as  test  engineers,  work  under  the  spe- 
cial direction  of  the  superintendent  of  power  stations 
and  in  co-operation  with  the  station  chief  engineer. 


1^1 


iAD  i  liMiii^ina^^ 


E.  C.  STONE 

Asst.  to  General  Manager, 
Duquesne  Light  Co. 


ml 


WITH  the  starting  up  of  the  Colfax  power  plant 
and  the  closing  of  a  ring  of  66  ooo  volt  lines 
around  the  Pittsburgh  District,  a  super-power 
system  has  been  established  for  supplying  the  City  of 
Pittsburgh  and  the  greater  part  of  Allegheny  and 
Reaver  Counties  with  electric  energy,  a  system  which  is 
adequate  for  all  present  needs  and  capable  of  develop 
ment  to  almost  unlimited  capacity. 

The  problem  of  transmitting  power  in  sufficient 
quantity  into  the  metropolitan  district  of  Pittsburgh, 
even  from  the  Brunot's  Island  Plant,  has  been  recog- 
nized as  a  most  serious  one  for  several  years.  The 
business  district  is  packed  into  a  very  small  area  near 
the  meeting  of  the  rivers,  and  the  manufacturing  dis- 
tricts have  been  concentrated  along  the  river  banks. 
Between  the  power  plant  and  these  districts  is  a  closely 
built  up  territory  with  narrow,  inadequate  streets.  To 
ti-ansmit  power  in  any  quantity  through  this  territory  by 
overhead  lines  could  not  be  considered  because  of  con- 
gested conditions,  and  to  transmit  it  in  sufficiently  large 
quantities  underground  was  almost  as  impracticable  be- 
cause of  the  enormous  quantity  of  heat  that  would  be 
developed  at  the  relatively  low  maximum  voltage  at 
which  underground  cables  can  be  operated. 

The  system  then  in  operation,  consisting  of  under- 
ground lines  along  all  available  streets,  had  already 
reached  its  limit,  so  that  a  radically  different  scheme 
had  to  be  developed  in  order  that  it  might  be  possible 
to  deliver  all  of  the  power  required  into  the  congested 
metropolitan  business  and  manufacturing  districts. 
After  careful  study,  a  high  voltage  transmission  ring 
encircling  the  district  was  decided  upon.  This  looked 
particularly  attractive  because  the  location  of  the  Col- 
fax plant  was  such  that,  with  the  Brunot's  Island  Plant, 
the  two  main  sources  of  power  supply  would  feed  into 
such  a  ring  from  points  almost  diametrically  opposite. 

The  working  out  of  this  transmission  ring  has 
solved  the  problem  eflfectively.  By  it,  a  practically  un- 
limited amount  of  power  can  be  transmitted  from  the 
two  main  power  plants,  over  transmission  lines  unre- 
stricted'by  their  surroundings  as  to  voltage  or  physical 
construction,  to  a  number  of  points  readily  accessible  to 
different  parts  of  the  main  industrial  district.  From 
these  points,  at  which  stepdown  sub-stations  are 
located,  enough  routes  are  available  for  transmission  at 
22  ooo  volts  of  all  power  that  is  now  required  or  is  likely 
to  be  needed  in  the  future  for  the  metropolitan  district 
and  surrounding  territory.  These  substations  are 
located  -^o  near  the  power  using  districts  that  transmis- 


sion is  accomplished  at  22  000  volts  without  excessive 
cost. 

Furthermore,  the  transmission  of  the  total  power 
supply  from  the  substations  into  the  city  over  so  many 
routes,  which  are  entirely  independent  of  each  other 
and  physically  a  considerable  distance  apart,  makes  for 
reliability  of  service,  since  any  trouble  condition  in  a 
given  location  such  as  lightning,  fire  or  external  inter- 
ference can  interrupt  only  a  relatively  small  part  of  the 
total. 

The  high  power  transmission  ring  encircling  the 
metropolitan  district  also  makes  an  adequate  and  reli- 
able supply  of  power  available  to  all  of  those  un- 
developed districts  immediately  around  the  congested 
area.  Already  some  of  the  surrounding  districts  have 
developed  very  rapidly  through  the  availability  of  Du- 
quesne Light  Company  power.  One  of  the  most  notable 
of  these  is  the  Bridgeville  area,  which  now  uses  some 
25  000  kilowatts  and  has  had  its  entire  power  develop- 
ment since  the  lines  of  the  Duquesne  Light  Company 
made  central  station  power  available  in  that  area. 

In  short,  such  a  high  voltage  transmission  ring  is 
the  only  scheme  by  which  it  is  physically  possible  to 
meet  the  growing  demands  for  power  in  the  congested 
areas  of  metropolitan  Pittsburgh.  It  was  realized,  how- 
ever, that  the  success  of  the  scheme  would  be  dependent 
on  its  reliability,  that  is,  on  its  ability  to  deliver  power 
continuously  as  well  as  in  sufficient  quantity.  Hence, 
the  greatest  stress  has  been  laid  on  this  requirement. 

The  layout  of  the  transmission  system  now  in  ser- 
vice and  under  construction,  which  will  take  care  of 
120000  kw  from  Brunot's  Island  and  120  000  kw  from 
Colfax,  is  shown  in  Fig.  i.  On  this  map  is  included 
the  location  of  the  main  and  peak  load  power  stations, 
principal  substations,  66  000  volt  transmission  ring  and 
the  principal  22000  volt  and  11  000  volt  transmission 
lines. 

The  66  000  volt  transmission  ring  consists  of  a  sys- 
tem of  lines  encircling  the  city  and  fed  from  opposite 
ends  by  the  two  main  power  plants,  Brunot's  Island  and 
Colfax,  with  a  spur  extending  down  the  Ohio  River  to 
feed  the  Ohio  and  Beaver  River  power  districts. 

Eight  stepdown  substations  have  been  installed  at 
eight  points  in  the  ring,  as  shown,  for  the  purpose  of 
stepping  the  voltage  down  to  22  000,  for  which  voltage 
the  spurs  from  the  substations  into  the  power  district 
are  built.  Hence,  including  the  lines  from  the  ring  sub- 
stations and  the  two  underground  lines  alreadv  in  ser- 


THE  ELECTRIC  JOURNAL 


Vol.  XVIir,  No.  5 


vice  from  Brunot's  Island,  the  power  supply  is  carried 
into  the  district  over  ten  distinct  routes. 

In  order  that  the  service  rendered  by  the  trans- 
mission ring  might  prove  adequate  to  meet  the  exacting 
power  demands  of  the  Pittsburgh  industrial  district,  the 
problems  to  be  encountered  in  its  operation  were  care- 


fully studied  in  advance  and  the  electrical  and  me- 
chanical details  of  the  system  were  worked  out  with  a 
view  to  obtaining  the  very  best  possible  operating  con- 
ditions. A  voltage  of  66  ooo  volts  was  adopted  for  this 
system  because  it  was  sufficiently  high  to  give  good 
transmission  economy  for  the  distances  involved  and 
not  high  enough  to  introduce  risks  from  insulator 
trouble  which  might  arise  from  the  large  amount  of  car- 
bon in  the  air  in  the  territory  covered.  In  accordance 
v.'ith  the  experience  on  other  systems,  it  has  been  found 
that  the  insulation  of  these  lines  is  sufficiently  strong 
to  protect  them  against  most  lightning  disturbances  and 
that  there  is  less  trouble  from  lightning  on  these  lines 
than  on  the  lower  voltage  lines. 

The  result  of  these  preliminary  studies  was  a  deci- 
sion that  the  transmission  system,  including  lines  and 
substations,  must  meet  the  following  requirements : 

a — All  lines  and  equipment  must  be  designed  witli  the 


FIG.    I — TERRITORY  SERVED  BY 
DUQUESNE  LIGHT  COMPANY 
TRANSMISSION  SUBSTATIONS 
Installed 
Capacity 
Station  Kv-a 

Ambridge   18  750 

Cheswick 12   500 

Deer  Creek    11  250 

Dravosburg    12  500 

Junction  Park 15  000 

North    25  000 

Wilmerding    20  000 

Woodville 25  000 

DISTRIBUTION    SUB-STATIONS 

Installed 

Capacity 

No.       .  Station  Kv-a 

1      Allegheny    2790 

Park    600 

Ambridge    1430 

Beaver  Falls 3125 

Bellevue    930 

Bloomfield 1565 

Carnegie 1875 

Christy  Park    3375 

College  Hill    2450 

Crafton    930 

East    End     11  250 

Economy   3500 

Esplen   1875 

Exposition    620 

Fallston   1875 

Forty-eighth  Street    ....    3750 

Friok    8065 

930 

Homestead    1000 

Homewood    1875 

Imperial 600 

Kennywood    560 

Manchester    3750 

Midland 375 

Milltown    1500 

Monaca    1500 

McKeesport    4680 

McKees  Rocks   1000 

Kew  Brighton 930 

North  Side   1395 


Oakland    3750 

Ontario  Street    2805 

Phipps 3665 

Point    375 

Rankin    4680 

Rochester    2645 

Sarah  Street 3750 

Sewickley    1500 


Chult 

Sixty-second  Street    2790 

Soho    2000 

South  Hills 930 

South  Heights    12 

Thirteenth   Street    15  000 

Thirtieth  Street    7500 

Tunnel 2895 

Verona 1395 


Washington  Junction   .  .  .  375 

West   End    375 

William  Pcnn    3230 

Wilkinsburg    3000 

Wilmerding 2000 

Wilson 1550 

Woodlawn   2100 

Woodville 980 


Ma}-,  1 92 1 


THE  ELECTRIC  JOURNAL 


213 


greatest  factor  of  safety  consistent  with  reasonable  econ- 
omy, with  a  view  to  giving  the  most  reliable  operation  pos- 
sible. 

b — Sufficient  spare  capacity  and  duplicate  equipment 
must  be  installed  throughout  to  carry  the  loads  satisfactorily 
without  curtailment  under  conditions  of  breakdown  reason- 
ably to  be  expected. 


be  carried  under  reasonable  breakdown  or  mainten- 
ance conditions.  Substations  are  equipped  with  dupli- 
cate busses  and  duplicate  transformers.  The  intercon- 
necting 22  000  volt  lines  between  the  various  substations 
are  such  that  any  one  substation  could  be  taken  out  of 
service  and  all  of  its  load  carried  from  the  remaining 
substations.  Finally,  if  necessary,  all  of  the  power  re- 
quired for  the  territory  could  be  handled  over  eight  of 
the  ten  transmission  routes  feeding  in  from  the  66  000 
volt  substations  and  from  Erunot's  Island. 

The  66  000  volt  transmission  circuits  are  carried  on 
steel  towers.     Each  tower  carries  two  three-phase  cir- 


I  !■  I  !■  >    -^  \i  I -.';iii\  I  I  \i.  (  ijnssiNu  Mii.\'()xr,,MiKi.A  ki\i-;r 

.\T  nugUESNE 

The  conductors  are  stranded  aluminum  cables  with  ^  inch 
stranded  steel  core,  having  a  conductivity  equivalent  to  4/0 
copper.  The  tower  in  the  foreground  is  200  ft  high  and  the  one 
on  the  hill-top  is  100  ft.  high. 


c — Disturbances   due   to   breakdowns 
mu.-t  l)e  reduced  to  a  minimum. 

d — The  power  supply  to  th 
not  be  interrupted  by  ordinary 
failures  on  the  transmission 
system.  In  every  case  defec- 
tive lines  or  equipment  must 
be  promptly  and  completely 
isolated  from  the  rest  of  the 
system. 

e — The  two  principal 
power  plants  must  be  solidly 
tied  together  by  the  transmis- 
sion ring.  Ample  synchroniz- 
ing power  must  be  provided 
and  the  two  plants  must  not  be 
broken  apart  by  short-circuits 
or  other  disturbances  in  the 
ring  or  on  other  parts  of  the 
system. 

f — Satisfactory  voltage 
conditions  must  be  provided  at 
the  sub-station  busses,  and 
provision  must  be  made  for 
the  proper  distribution  of 
wattless  current  between  the 
power  plants. 

Requirement  a  was  met 
by  providing  liberal  factors 
of  safety,  mechanically  and 
electrically,  on  all  equipment. 
To  take  care  of  the  require- 
ment h,  ample  line  capacity  is 
provided,  so  that  all  loads  can 


and   other  causes 


arious  jub-stations  must 


FIG.    3 — ARRANGEMENT    OK    WIRES    ON    TOWER 

cuits  and  two  ground  wires.  The  towers  are  of  sub- 
stantial construction  and  are  considerably  heavier  than 
average  practice  would  indicate  for  this  class  of  work. 
On  the  average  there  are  six  towers  per  mile. 

For  the  greater  part  of  the  system,  each  circuit 
consists  of  three  4/0  bare  stranded  copper  cables.  One 
section  of  the  line,  however,  from  the  Monongahela 
River  crossing  west  to  Woodville,  a  distance  of  about 
18  miles,  is  constructed  of  alutninum  cable  with  steel 
core.  This  conductor  has  a  conductivity  equivalent  to 
4/0  copper  and  its  core  is  a  seven-strand  steel  cable, 


Lightning  Arresters 
Center  Lin 


"""'^CenterLine  ^^'^"^ 
of  Breakers 

FIG.   4 — DIAGRAMMATIC   PLAN  OF  DRAVOSBURG   SUBSTATION 


214 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII.  No.  5 


5/16  in.  in  diameter.  The  aluminum  cable  was  in- 
stalled in  conformity  to  the  standard  specifications  of 
the  Aluminum  Co.  of  America,  by  whom  it  was  fur- 
nished. This  section  was  put  in  as  an  experiment  and 
its  performance  will  be  carefully  compared  with  the 
performance  of  the  adjacent  copper  circuits. 

The  spans  over  the  Allegheny  and  Monongahela 
Fivers,  the  latter  being  2360  ft.  between  towers  and  the 
longest  span  on  the  system,  are  both  of  steel  core 
aluminum  cable  as  described  above.  Throughout  the 
system,  the  ground  wires  are  of  %  in-,  stranded  steel 
cable.  Suspension  insulators  are  used,  there  being  five 
units  in  the  suspension  strings  and  six  in  the  strain 
strings.  The  porcelain  used  in  the  insulators  when 
under  strain  is  in  compression  rather  than  in  tension. 
Each  insulator  unit  will  require  approximately  95000 

r-i      Line  No  '. 

13^ 


f^    t  ]  t      Trans, 


i  Disc  Switch 
VOfl  Or  Breaker 


22000  Vol!  Buses 


22  000  Volt  Feeders 


22  000  Volt  Feeders 


FIG.    5 — SINGLF.-LINE  DIAGRAM    OF   A   TYPICAL   SUBSTATION  LAYOUT 

volts  for  flashover  and  140000  volts  for  puncture.  A 
high  factor  of  safety  above  operating  voltages  is  thus 
assured. 

The  right-of-way  selected  for  the  66  000  volt  line 
was  made  as  near  to  the  city  power  districts  as  possible, 
v.'ithout  placing  any  limitations  on  adequate  construc- 
tion. Towers  are  located  on  private  rights-of-way  and, 
because  of  this  and  their  rugged  construction,  they  will 
be  practically  free  from  external  interference,  which  is 
the  cause  of  so  many  failures  on  ordinarj'  pole  lines. 

The  substations,  like  the  lines,  are  of  the  simplest 
and  most  rugged  construction.  It  will  be  seen  from  Fig. 
5  that  all  incoming  lines  are  sectionalized  where  they 
enter  the  station,  and  that  two  transformer  banks  are 
installed,  each  transformer  bank  being  controlled  by  a 
separate  switch.  A  tie  switch  is  also  provided  by 
which  both  transmission  circuits  can  be  operated  in 
parallel. 


The  oil  switches  on  the  66  000  volt  side  have  a  rup- 
turing capacity  of  72  amperes  per  phase  at  66  000  volts. 
These  are  adequate  for  the  generating  capacity  feeding 
the  system. 

Each  main  transformer  bank  consists  of  three 
single-phase  radiator-cooled  units.  Delta  connection  is 
used  on  the  high  tension  side  and  star  on  the  low,  this 
arrangement  being  decided  upon  in  order  that  the  neu- 
tral of  the  22  000  volt  system  could  be  grounded  at  each 
sub-station,  a  very  necessary  provision  on  a  system  of 
this  magnitude.  A  spare  transformer  unit  is  also  pro- 
vided which  can  be  promptly  cut  in  to  replace  any  unit 
that  may  fail.  The  second  transformer  banks  have  not 
yet  been  installed  at  the  Wilmerding  and  Dravosburg 
stations,  but  will  be  put  in  as  soon  as  load  requirements 
make  it  necessary. 

r-,.        .      66000  Volt  Lines  Each      t  Taus  f  oriiicr     is 

equipped  with  an  oil  con- 
serv'ator,  which  performs  two 
functions.  It  prevents  mois- 
ture from  getting  into  the  oil 
in  the  transformer  and 
lessens  the  chances  of  oil  ex- 
plosion in  case  of  trans- 
former breakdown  by  keep- 
ing the  transformer  itself 
at  all  times  completely  filled 
with  oil.  It  thus  consti- 
tutes an  important  element 
of  safety  especially  on  out- 
door transformers  which  are 
subject  to  wide  ranges  of  sur- 
rounding temperature. 

The  conservator  consists 
essentially  of  a  tank  mounted 
above  the  transformer  and 
connected  to  the  transformer 
through  an  oil  pipe.  This 
pipe  enters  the  tank  at  a  point 
considerably  above  the  bot- 
tom of  the  tank,  so  that  what- 
settles  in  the  bottom  of  the 
readilv      drawn      ofif.       This 


ever   moisture    gets    in 
tank      and      can      be 

effectively  keeps  the  moisture  out  of  the  transformer 
proper.  By  always  keeping  sufficient  oil  in  the  unit  to 
maintain  the  oil  level  at  some  point  in  the  conservator, 
the  contact  between  oil  and  air  is  kept  entirely  out  of 
the  transformer,  thus  reducing  the  chances  of  an  explo- 
sion which  might  result  from  a  flash  in  the  transformer 
acting  on  an  explosive  mixture  which  might  be  formed 
by  the  oil  vapor  and  the  air  above  the  oil  level. 

On  the  22000  volt  side,  two  busses  are  installed, 
regular  and  emergency.  Oil  circuit  breakers  with  a 
rupturing  capacity  of  12  300  amperes  at  25  000  volts 
connect  the  outgoing  feeders  with  the  regular  bus.  The 
feeders  can  be  connected  to  the  emergency  bus  only 
through  disconnecting  switches,  so  that  this  bus  serves 
mainlv  as  a  connecting  link  between  the  transformers 


May,  1 92 1 


THE   ELECTRIC  JOURNAL 


215 


and  outgoing  feeders  in  case  of  trouble  with  the  line 
circuit  breakers  or  the  regular  bus.  Provision  has  been 
made  so  that  later  on,  if  found  desirable,  oil  circuit 
breakers  can  be  installed  also  between  each  feeder  and 
the  duplicate  bus.     The  neutral  of  the  22  000  volt  trans- 


iWllClltS    Ai    l_lKA\USl:rKi.    SL1;S1ATI0.N' 

former  windings  will  be  connected  to  ground  through  a 
resistor  of  15  ohms  with  a  rated  capacity  of  865  am- 
peres for  30  seconds. 

All  primary  ecjuipment  is  out  of  doors,  mounted  on 
substantial  concrete  foundations.  A  small  brick  house 
however,  is  provided  to  protect  the  switch  control 
equipment,  to  house  a  synchronous  condenser  and  to 
provide  shelter  for  repairing  the  big  transformers. 
Synchronous  condensers  are  already  installed  at  the 
Woodville  and  Dravosburg  substations.  In  case  of 
trouble,  any  one  of  the  main  transformers  can  be  moved 
by  means  of  a  truck  from  its  regular  location  into  the 
building.  Once  in  the  building,  a  defective  unit  is  pro- 
tected from  the  weather  and  repairs  can  readily  be 
made.  Each  building  is  equipped  with  block  and  tackle 
for  raising  a  transformer  out  of  its  case. 

The  22  000  volt  circuits  are  ordinarily  mounted  on 
wood  poles.  Western  red  cedar  poles  are  used  con- 
forming to  the  standard  dimensions  known  as  Class  B 
in  the  N.  E.  L.  A.  specifications.  Two  circuits  are 
carried  on  a  pole,  the  construction  being  a  triangular 
arrangement  of  the  conductors  on  two  crossarms  with 
36  inch  spacing  between  conductors.  At  the  top  of  the 
pole  is  a  crossarm  carrying  two  No.  4  hard-drawn 
copper  ground  wires  mounted  on  porcelain  insulators  of 
6600  volt  rating.  These  wires  are  grounded  at  intervals 
of  three  to  five  poles  depending  on  local  conditions. 
Operating  results  indicate  that  the  double  ground  wire 


is  a  very  substantial  protection  to  the  circuit  against 
lightning  and  the  circuits  so  protected  show  materially 
less  breakdowns  than  those  protected  by  a  single  ground 
wire  or  those  with  no  ground  wire. 

Requirements  c,  d  and  e,  are  met  by  grounding  the 
neutral  of  the  66  000  volt  system  through  resistances  at 
both  power  plants  and  by  sectionalizing  the  system  into 
a  number  of  relatively  small  parts  connected  through 
circuit  breakers  of  ample  rupturing  capacity. 

The  neutral  resistances  at  each  power  plant  are 
rated  at  95  ohms  with  a  capacity  of  400  amperes  for  10 
seconds.  It  was  the  intention  to  choose  a  value  of  re- 
sistance which  would  be  low  enough  to  prevent  high 
transient  voltages,  but  high  enough  to  limit  the  currents 
flowing  into  grounds  to  such  an  extent  that  the  volt- 
age disturbances  created  thereby  will  not  interfere  with 
the  operation  of  synchronous  and  other  motors  con- 
nected to  the  system.  The  limiting  of  ground  currents 
in  this  manner  has  necessitated  special  relay  arrange- 
ments apart  from  the  overload  relays  in  order  to  cut 
out  the  grounded  sections.  It  is  the  usual  experience 
with  high-tension  systems  that  most  failures'  result  in 
grounds  rather  than  in  short-circuits,  so  that  the 
grounding  of  the  neutral  in  this  manner  should  prove 
very  effective  as  a  safeguard  to  sei-vice.  The  resist- 
ances' of  the  above  value  initially  inserted  in  the  neutral 


KIC.    7 — TYPICAL    I.XblAU.AllOX    ijF    LIGHTNING    ARRL^  1  ' 
STANDARD    TRANSMISSION    TOWER 

The  line  conductors  are  looped  down  to  the  lightning  arrester 
and  the  choke  coils  are  placed  in  a  vertical  position. 

must  be  considered  experimental  and  will  be  subject  to 
change  if  further  experience  in  operation  indicates  that 
some  other  value  will  give  improved  conditions. 

Althoudi    most    breakdowns    are    grounds,    short- 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


circuits  are  bound  to  develop  occasionally,  and  accord-  lays.  This  current  will  not  be  o-reat  enouo-h  to  close 
ingly  all  oil  switches  have  been  installed  with  sufficient  the  contacts  of  the  overload  relays.  It  will  however 
rupturing  capacity  to  break  the  heaviest  short-circuit  have  sufficient  magnitude  and  proper  direction  to  close 
Vv'hich  they  could  be  called  upon  to  open.  Those  at  the  the  contacts  of  the  ground  relay  which  controls  the  cir- 
Colfax  plant  have  a  rupturing  capacity  of  12400  am-  cuit  breaker  of  the  faullv  line.  If  the  line  short-cir- 
cuits, the  e.Kcess  current 
will  cause  current  to  flow 
through  the  overload  relays 
nly.  This  current  will  be 
(it  sufficient  magnitude  and 
in  a  proper  direction  to 
close  the  contacts  of  one  or 
more  of  the  overload  relays 
which  control  the  circuit 
breakers  of  the  faulty  line, 
pjy  this  scheme,  grounds 
a  n  d  short-circuits  are 
cleared  by  separate  devices. 
This  makes  it  possible  to 
clear  ground  currents 
which  are  smaller  than  the 
normal  load  currents  auto- 
matically, a  very  necessary 
( ondition  when  the  neutral 
"f  the  system  is  grounded 
through  a  relatively  high 
resistance. 

The  protective  ar- 
rangement for  the  sub- 
station bus  wiring  is  shown 
same     as     that     ordinarilv 


Each  transformer  is  mounted  on  .vheels  and  can  be  pushed  along  on  its  track  to  the  car  as 
shown.  The  car  with  the  transformer  is  then  moved  to  the  track  at  the  entrance  of  the 
building,  and  the  transformer  is  pushed  into    the  building  for  repairs. 


peres  at  66000  volts,  while  those  at  the  substations  have 
a  rupturing  capacity  of  7200  ainperes  at  the  same  volt- 
age. A  one-line  diagram  of  the  high-tension  lines  and 
switches  is  shown  in  Fig.  10.  All  lines  are  sectionalized 
at  the  substations,  and  the  high-tension  side  of  each  sub- 
station is  divided  into  four  [tarts,  two  bus  sections  and 
two  transformer  sections.  The  automatic  protective 
scheme  is  designed  to  cut  out  any  section  of  line  or  sta- 
tion in  which  trouble  may  develop  without  interrupting 
any  other  sections. 

The  protection  on  the  lines  contemplates  their  op- 
eration in  pairs,  paralleled  at  each  substation.  In  case 
of  a  ground  or  short-circuit  on  any  section  of  line  be- 
tween substations,  the  circuit  breakers  at  both  ends  of 
the  defective  line  will  immediately  open,  thus  clearing 
the  system  of  the  trouble  without  interruption  to  ser- 
vice. 

The  series  transformers  of  the  two  lines  are  bal- 
anced against  each  other  so  that  under  nor- 
mal conditions,  with  each  pair  of  lines  in  parallel 
between  stations,  the  same  current  will  flow  in  both 
lines,  there  will  be  no  current  in  the  relays,  and 
all  relay  contacts  will  be  open.  In  the  control  circuit, 
the  contacts  of  the  overload  and  ground  relays  are  in 
parallel  with  each  other,  so  that  the  closing  of  either 
will  trip  the  breaker.  If  a  line  breaks  down  to  ground 
the  excess  current  due  to  the  ground  will  cause  current 
to  flow  through  both  the  overload  and  the  ground  re- 


in Fig.  II.  It  is  the 
used  to  protect  generator  windings  and  leads. 
When  the  current  flowing  into  the  bus  through  one  or 
more  of  the  switches  is  equal  to  the  current  flowing  out 
over  the  other  switches,  there  is  no  current  in  the  relavs 


r,  ih  M  i.i'"i  MiING  RESIST.ANCE 
A  standard  resistance  unit  lor  grounding  the  neutral  of  the 
22  000  volt  system  at  the  substations.  The  resistors  for  ground- 
ing the  66  000  volt  system  are  of  the  same  general  construction, 
but  are  insulated  for  higher  voltages.  Note  the  transformer  oil 
conservator  on  the  left. 

and  all  the  breakers  remain  closed.  When,  however,  a 
failure  develops,  the  currents  flowing  into  the  bus  ex- 
ceed those  flowing  out  and  current  appears  in  the  relays 
in  one  or  more  phases,  thereby  opening  the  two  line 


May,  1921 


THE   ELECTRIC  JOURNAL 


217 


switches  and  the  transformer  switch,  and  clearing  the 
trouble. 

The  transformer  banks  are  protected  in  exactly  the 
same  manner  as  the  bus  sections,  as  shown  in  Fig.  12. 
In  this  case,  however,  an  additional  set  of  series  trans- 
formers has  to  be  placed  in  the  relay  circuit  to  take  care 
of  the  difference  in  phase  of  the  primary  and  secondary 
c;rcuits,  due  to  the  fact  that  the  main  transformers  are 
connected  delta-star,  and  also  to  compensate  for  the  dif- 
ferent saturation  characteristics  of  the  66  000  volt  and 


Juncl.on  Park 
X5°-|      15  000 


-o-  Oil  Circuit  Breaker 
^    3-Phase  Transformer  Bank 


Deer  Creek     Chcswick 
(tempj  I  temp  I 

10  000  10  000 


FIG.    10 —  TYPIC.-\L   SINGLE-LINE   DIAGRAM    OF   THE   LINES   AND 
SWITCHES   ON   THE  HIGH-TENSION   RING 

22  000  volt  series  transformers.  If  this  difference  in 
saturation  was  not  compensated  for,  the  transformers 
would  be  cut  out  on  heavy  overloads  beyond  the 
22  000  volt  bus.  In  case  of  a  transformer  failure,  the 
circuit  breakers  on  the  high  and  low^-tension  sides  of  the 
transformer  bank  are  afifected  and  the  high-tension  tie 
breakers  are  opened. 

The  66  000  volt  series  transformers  are  of  the 
bushing  type  in  all  cases,  and  are  mounted  on  the 
terminals  of  the  oil  circuit'  breakers.  Separate  series 
transformers  are  required  for  the  protection  of  each 
section,  so  that  all  the  terminals  of  both  poles  of  the 
breakers  carry  these  bushing  type  series  transformers. 

It  will  be  seen  that  the  entire  protective  scheme  is 
based  on  the  differential  principle.  Under  normal  con- 
ditions, no  current  flows  in  the  relays,  but  if  a  failure 
develops,  a  current  proportional  to  the  failure  current, 
is  set  up  only  in  the  relays  controlling  the  breakers  on 
the  defective  section.  On  the  lines  the  differential  prin- 
ciple is  made  use  of  by  grouping  them  in  pairs.  This 
differential  arrangement  pennits  of  relay  settings  which 
will  allow  the  circuit  breaker  to  open  on  failure  current 
before  such  current  is  built  up  to  the  magnitude  of  an 
overload  and  without  time  delay.  Hence,  defective  sec- 
tions are  cleared  in  the  shortest  possible  time,  which  is 
of  obvious  advantage  to  the  system  as  a  w^hole,  to  the 
elements  that  are  broken  down,  and  to  the  users  of  the 
service. 

Furthermore,  any  amount  of  current  can  flow  be- 
tween the  busses  of  the  two  power  plants  without  open- 
ing the  circuit  breakers  on  the  tie  lines  and  separating 
the  plants.  Excessive  cross  currents  between  power 
plants  may  be  caused  by  sudden  changes  in  load,  de- 


fective governor  operation,  or  heavy  short-circuits  on 
lines  other  than  the  tie  lines  connected  to  the 
power  station  bus.  If  such  rushes  of  current 
are  able  to  open  the  tie  lines  between  the  plants, 
it  almost  invariably  happens  that  one  plant 
i?  overloaded  and  the  other  underloaded.  This  causes 
,-.  considerable  discrepancy  in  the  frequencies  of  the  two 
plants  and  generally  means  interrupting  enough  addi- 
tional load  on  the  overloaded  plant  to  get  the  frequency 
up  to  normal  before  synchronizing  can  take  place.  The 
\ery  important  requirement  that  the  plants  must  not 
l)reak  apart  in  system  disturbances  as  long  as  there  is  a 
line  available  between  them  is  thus  efficiently  met. 

The  only  circuit  breaker  on  the  66  000  volt  system 
which  is  set  to  open  on  overload  is  the  one  on  the  high- 
tension  side  of  the  step-up  transformers  at  the  Colfax 
Plant,  and  this  is  given  such  a  high  setting  that  it  w^ill 
not  open  except  on  a  short-circuit  at  the  Colfax  bus. 

On  the  outgoing  22  000  volt  circuits  two  relays  take 
c.ire  of  overloads  and  one  takes  care  of  grounds.  The 
arrangement  is  shown  in  Fig.  13. 

Careful  attention  to  the  proper  maintenance  of 
voltage  conditions  at  substations  and  to  proper  distribu- 
tion of  the  wattless  current  is  necessary,  because  the  re- 
actance of  the  66000  volt  system  is  very  high,  and  the 
voltage  drop  in  this  system  is  superimposed  on  that  of 
the  22  000  volt  and  1 1  000  volt  systems  which  carry  the 
power  from  the  stepdown  substations  to  the  user.  The 
high  reactance  of  the  66  000  volt  system  is  appreciated 
when  it  is  realized  that  the  reactance  of  the  step  up  and 
siep  down  transformers  alone  totals  about  14  percent  at 
rated  loads ;  that  under  conditions  of  full  load  at  80 
percent    power- factor    the    inherent    regulation    at    the 


FIG.    II — RELAY    SYSTEM    FOR  THE   SUBSTATION   BU.S 

Normal  Conditions  A-B=C ;  D=0 

Fault  in  Bus  A-B  C ;  D  O;  C  O  relay  closes  trip  circuits. 
Designed  to  clear  trouble  on  the  substation  bus  between  the  line 
switches  and  the  transformer  switch.  In  case  of  failure  of  the 
bus  the  currents  entering  are  greater  than  those  leaving  and  a 
current  proportional  to  the  difference  or  failure  current 
flows  in  one  or  more  of  the  CO  relays.  When  the  con- 
tact of  one  of  these  relays  closes,  the  secondary  circuit  operates 
a  multi-contact  relay  which  closes  the  trip  circuits  on  both  the 
line  and  the  transformer  circuit  breakers,  thus  clearing  the 
trouble. 

22000  volt  bus  of  the  average  substation  is  20  percent; 
and  that  a  dead  short-circuit  20  miles  from  the  power 
house  on  a  66  000  volt  line  will  pull  only  about  five 
times  the  normal  full-load  current  of  the  line.  Because 
of  this  high  reactance,  the  proper  handling  of  the  watt- 


2l8 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


less  current  on  the  system  is  particularly  important. 

To  provide  proper  voltage  conditions,  large  syn- 
chronous condensers  are  installed  at  the  various  substa- 
tions and  the  Colfax  plant  is  laid  out  for  operation  over 
a  15  percent  range  in  voltage.  At  the  present  time  7500 
kv-a  condenser  units  are  installed  at  the  Dravosburg 
and  Woodville  Substations ;  at  the  48th  St.  and  Beaver 
Falls  substations,  which  take  practically  the  entire  out- 
put of  the  North  and  Junction  Park  66  000  volt  substa- 
tions; and  at  the  Rankin  station.  These  synchronous 
condensers  perform  the  double  function  of  regulating 
the  voltage  at  the  22000  volt  substation  busses  and  of 
increasing  the  capacity  of  the  transmission  system  by 
raising  the  power-factor  and  reducing  line  drops.  The 
increase  in  system  capacity  in  this  manner  practically 


this  manner.  If  the  power  factor  of  the  load  is  80  per- 
cent, Curve  d  gives  the  regulation  which  would  prevail 
over  different  transmission  distances,  if  no  condensers 
were    used.     Through    the   proper   use   of    condensers. 


FIG.     12 — RELAY    SYSTEM     FOR    MAIN    TRANSFORMER    BANKS    IN 
SUBSTATIONS 

Like  the  bus  relay  system,  this  is  a  differential  system 
which,  in  case  of  trouble  in  the  transformers,  causes  a  current 
proportional  to  the  fault  current  to  flow  in  one  or  more  of  the 
CO  relays.  When  the  contacts  of  one  of  the  relays  close  the 
contacts  on  a  multi-contact  relay  are  closed,  thus  tripping  the 
high  and  low  tension  transformer  circuit  breakers  and  the  tie 
breaker. 

pays  the  cost  of  the  condensers,  so  that  the  voltage 
regulation  is  obtained  without  expense.  Since  voltage 
drop  increases  with  the  length  of  line  and  decreases  with 
improvement  in  power-factor,  the  substations  near  the 
power  plant  are  operated  at  fairly  low  power-factors, 
thereby  giving  relatively  poor  regulation,  while  those 
farthest  away  are  kept  near  unity  power-factor,  thereby 
tending  to  offset  the  greater  drop.  This  fortunately, 
also  gives  the  best  economy  of  operation,  and  the  aver- 
age result  of  high  power-factor  at  distant  stations  and 
low  power-factor  at  nearby  stations  is  to  provide  the 
most  economical  power-factor  at  the  power  plants,  as 
well  as  to  equalize  the  voltage  regulation  at  the  various 
substations. 

In  Fig.  14  are  shown  the  results  which  can  be  ob- 
tained through  the  use  of  synchronous  condensers  in 


FIG.    13 — RELAY   SYSTEM   ON   22  000  VOLT   FEEDERS  KT  DRAVOSBURG 

however,  constant  full  load  voltage  can  be  obtained  for 
all  stations  regardless  of  the  transmission  distance,  as 
shown  by  curve  c. 

In  order  to  get  the  voltage  indicated  by  curve  c  the 
power-factor  of  the  load  must  be  raised  to  the  value  in- 
d:cated  by  curve  b.  The  plan  contemplated  provides 
lor  the  same  secondary  voltage  at  all  substations  on  the 
rmg,  and  this  is  accomplished  by  the  method  indicated 
above. 

The  voltage  at  Brunot's  Island  is  fixed,  due  to  con- 
ditions in  the  previously  existing  transmission  system 
rnd  substations.  The  Colfax  plant  is  designed  to  op- 
crate  over  a  range  of  voltage  from  lo  500  to  12  000, 
V.  hich  permits  of  the  proper  distribution  of  the  wattless 
current  between  the  Brunot's  Island  and  Colfax  plants. 


FIG.    14 — EFFECT   OF    SYNCHRONOUS    CONDENSERS    IN    IMPROVING 
VOLTAGE  REGULATION 

Variation  of  the  Colfax  voltage  in  conjunction  with  the 
synchronous  condensers  is  also  of  use  in  maintaining 
the  desired  voltage  at  the  substations.  When  operating 
two    power   plants    in   parallel    over   a   high    reactance 


May,  1921 


THE  ELECTRIC  JOURNAL 


219 


transmission  system,  the  proper  distribution  of  the 
wattless  current  becomes  a  very  important  element, 
since  if  either  plant  is  required  to  carrj'  more  than  its 
share  of  the  wattless,  it  may  be  necessary  to  run  addi- 
tional generating  capacity  to  avoid  overheating.  The 
provisions  for  voltage  adjustment  above  referred  to 
will  adequately  take  care  of  this  situation.  Standard 
voltage  regulators  are  installed  to  regulate  the  bus  volt- 
age at  the  Brunot's  Island  and  Colfax  Power  Stations 
«".d  at  all  substations  where  synchronous  condensers  are 
l(!cated. 

It  has  already  been  pointed  out  that  reliability  of 
service   was   a   prime   consideration   in   the   design  and 


construction  of  this  transmission  system.  It  is  believed 
that  with  the  simple  and  rugged  construction  of  lines 
and  stations,  extra  heavy  installation  throughout,  high 
capacity  circuit  breakers,  spare  equipment  at  all  points, 
adequate  protective  features  including  ground  resist- 
ance, lightning  arresters,  complete  relay  system,  and 
multiple  transmission  routes  for  delivering  power  into 
the  district  served  from  both  main  power  plants,  this 
transmission  system  typifies  the  highest  development  of 
the  art  at  the  present  time,  and  will  render  to  the  dis- 
trict served  an  electric  power  service  thoroughly  reliable 
and  fully  adequate  to  meet  the  exacting  demands  that 
v,'ill  be  made  upon  it. 


Pov7®r  Il^qiironiaiits  m  fwz 


Piti:si)ijr2]i 


Dlsfrici: 


JOSEPH   McKINLEY 

General  Contract  Agent, 
Duquesne  Light  Company 


PITTSBURGH  is  located  at  the  confluence  of  the 
Allegheny  and  Monongahela  Rivers  which  forms 
the  Ohio.  It  is  the  financial,  educational  and 
social  center  of  a  great  industrial  district,  tributary  to 
each  of  these  navigable  streams  for  a  distance  of  more 
than  50  miles,  within  whose  boundaries  are  located  over 
100  different  municipalities.  This  district,  witli  an 
area  of  approximately  1000  square  miles  in  Allegheny 


;ire  dependent  upon  this  region  for  45  percent  of  their 
raw  materials  for  agricultural  implements,  hardware 
products  and  automobiles.  In  terms  of  the  production 
of  the  United  States,  the  district  produces  nine  percent 
of  the  bituminous  coal,  24  percent  of  the  pig  iron;  50 
percent  of  the  crucible  steel ;  28  percent  of  the  finished 
rolled  iron  and  steel  products;  60  percent  of  the  tin- 
plate;    65    percent    of    the    glassware    products;    and 


and  Beaver  Counties,  with  an  aggregate  population  of     possesses  20  percent  of  the  Bessemer  converters  and  35 


about  I  300  000,  is  known  as  the  Pittsburgh  District, 
and  is  served  by  the  Duquesne  Light  Company. 

Its  pre-eminent  position  as  an  industrial  district  is 
due  to  its  favorable  location,  natural  resources,  ideal 
climate  and  transportation  facilities.  There  are  avail- 
able ove:-  80  miles  of  excellent  harbor  sites,  affording 
cheap  water  transportation  leading  direct  to  the  Gulf  of 
Mexico,  the  Panama  Canal,  and  the  ports  of  the  world. 
The  Federal  Government  now  has  under  way  a  very  ex- 
tensive improvement  of  the  Ohio  River  which,  when 
completed,  will  eliminate  the  obstacle  of  slack  water  and 
render  possible  barge  shipments  of  coal  and  other  pro- 
ducts at  all  seasons  of  the  year.  Also,  the  district  has 
exceptional  rail  transportation  service,  as  six  rail- 
loads  with  many  branches  radiate  from  the  City  of 
Pittsburgh  in  all  directions,  reaching  every  section  of 
the  country.  Furthermore,  it  is  traversed  by  several 
interurban  lines  affording  transportation  between  many 
of  the  municipalities  in  the  district  and  the  City  of 
Pittsburgh.  Some  idea  of  the  magnitude  of  its  indus- 
trial activities  and  the  extent  of  its  natural  resources 
may  be  gained  from  the  fact  that  there  are  over  2600 
manufacturing  establishments  engaged  in  over  250  dif- 
ferent lines  of  production,  so  diversified  as  to  embrace 
almost  all  the  commodities  for  which  the  commerce  of 
the  United  States  is  famous. 

Within  a  radius  of  40  miles  the  production  is  on 
such  a  vast  scale  as  almost  to  stagger  the  imagination. 
Statistics  show  that  manufacturers  of  the  United  States 


percent  of  the  open  hearth  furnaces.  The  annual  ton- 
nage of  this  vast  production  is  two  and  one-half  times 
greater  than  that  of  New  York,  London  and  Hamburg 
combined,  both  before  and  after  the  war.  The  value 
of  production  in  Allegheny  County  for  the  years  1916- 
1919  is  shown  in  Fig.  i. 

Compared  to  the  industries  of  the  world,  the  dis- 
trict numbers  among  its  industries  the  largest  structural 
steel  plant ;  the  largest  glass  manufacturing  plant ;  the 
largest  independent  wire  manufacturing  plant;  the  larg- 
est air  brake  manufacturing  plant;  the  largest  corpora- 
tion manufacturing  rolling  mill  machinery;  the  largest 
pickling  and  preserving  plant;  the  largest  radium  and 
vanadium  plants,  and  the  largest  cork  manufacturing 
plant.  ' 

Pittsburgh  is  the  center  of  an  immense  jobbing 
trade  supplying  over  ten  million  people  and  producing 
an  annual  business  surpassing  the  billion  mark.  It  is 
the  third  city  in  the  country  in  the  distribution  of  pro- 
duce. It  is  the  strongest  financial  community  in  the 
country,  with  a  banking  surplus  of  $100000000,  which 
is  exceeded  only  by  New  York  and  Philadelphia,  with 
banking  deposits  per  capita  larger  than  any  other  city  in 
the  United  States,  and  with  bank  clearings  greater  than 
Cleveland  and  Cincinnati  combined.  The  average  per 
capita  wealth  of  the  district  is  over  $2500,  and  the  daily 
payroll  exceeds  two  million  dollars,  while  the  total  pro- 
duction, valued  at  around  two  billion  dollars  annually,  is 
greater  than  that  of  each   of  21   states  of  the  Union. 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  5 


Consequently,  new  industries  are  rapidly  locating  in  this 
district,  where  necessaiy  raw  materials  are  produced; 
where  manufacturing  machinery  and  tools  are  exempt 
from"  taxation ;  where  there  is  an  abundance  of  skilled 
labor;  and  where  there  are  many  desirable  sites  avail- 
able from  the  standpoint  of  shipping,  housing  employes, 
and  an  adequate  and  dependable  supply  of  power,  which 


1915   1916   1917   1918   1919 


FIG.     I — VALUE    OF    PRODUCTION    IN    .^LLEGHEXY    COUNTY    FOR    THE 
YEARS    I915   TO   I919 

can  be  obtained  from  the  ring  transmission  system  of 
the  Duquesne  Light  Company  encircling  the  district. 

With  the  development  of  industrial  activity  in  the 
district,  the  load  of  the  Duquesne  Light  Company  has 
increased  from  8000  kw  in  i898,'to  320000  kw  in  1920. 
The  amount  of  this  increase  in  connected  load  annually 
from  191 3  to  1920  is  shown  in  Fig.  2,  together  with  the 
yearly  increase  in  the  number  of  customers  and  kilo- 
watt-hour output  during  the  period.  Prior  to  1913,  this 
growth  was  due  in  part  to  the  consolidation  of  several 
companies;  the  conversion  to  central  station  service  of 
numerous  isolated  plants,  and  the  natural  growth  of  the 
community  served.  Since  that  time,  the  growth  has 
been  entirely  due  to  the  replacement  of  isolated  plants 
Vv-ith  central  station  power  and  the  nornial  increase  in 
the  power  requirements  in  the  district.  The  consump- 
tion per  capita  during  this  period  has  more  than 
doubled,  so  that  for  1920  it  had  reached  665  kw-hrs. 

During  this  time  the  Company  has  been  very  suc- 
cessful in  replacing  with  its  service  a  great  number  of 
isolated  plants  which  found  that  they  could  no  longer 
generate  their  power  as  cheaply  as  they  could  purchase 
it.  This  has  been  due  largely  to  the  ?ncreased  costs  of 
fuel,  labor  and  maintenance.  Due  to  the  conditions 
created  by  the  war  such  plants  were  able  to  dispose  of 
their  equipment  satisfactorily  and  invest  the  proceeds  in 
tlie  production  requirements  of  their  business.  There 
were  others  who  were  confronted  with  a  limited  space, 
which  it  was  found  desirable  to  convert  to  productive 
capacity — an  important  item  to  consider  in  the  cost  of 
generating  power. 

The  application  of  electric  power  for  industrial 
heating,  as  exemplified  by  the  electric  furnace  and  elec- 
tric oven,  has  had  a  phenomenal  development  in  the  dis- 
trict. This  is  indicated  by  the  fact  that  twenty-three 
electric  steel  and  alloy  furnaces  have  been  contracted 
for,  a  load  totalling  33  000  kw,  of  which  seventeen  have 


been  connected,  representing  a  load  of  22  000  kw  and  a 
consumption  of  about  eight  percent  of  the  total  power 
generated  by  the  Duquesne  Light  Company  and  com- 
prising six  percent  of  the  total  number  operating  in  the 
United  States.  For  the  melting  of  brass  three  electric 
furnaces  have  been  contracted  for,  giving  a  500  kw 
load.  There  are  many  installations  of  ovens  for  elec- 
trical heat  treatment  of  steel  and  enameling,  which  pro- 
cess is  especially  satisfactory  on  account  of  the  accurate 
control  of  temperatures  and  atmospheric  conditions  de- 
sired. 

The  domestic  business  has  been  particularly  flour- 
ishing as  the  result  of  wiring  many  old  houses  and  the 
increased  use  of  household  appliances,  which  have 
not  only  been  a  great  convenience,  but  in  many  cases 
I'.ave  actually  been  the  means  of  solving  the  domestic 
servant  problem. 

The  total  power  requirements  of  the  Pittsburgh 
Pvailways  Company,  operating  street  cars  in  the  City  of 
Pittsburgh  and  several  interurban  lines  to  nearby  cities, 
are  furnished  by  the  Duquesne  Light  Company. 

The  municipal  and  rural  lighting  load  has  greatly  in- 
creased, due  to  the  demand  for  improvement  in  the 
lighting  of  streets  and  highways,  which  resulted  in  the 
replacement  of  gas  lighting  by  electric  lighting,  the 
former  having  been  used  to  a  greater  extent  than  in 
most  cities  on  account  of  the  abundance  of  natural  gas 
available  in  this  territory. 


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HG.   2— INCRE.'VSE  IN  NUMBER  OF  CUSTOMERS,  CONNECTED  LOAD  AND 
KW — HR.  OUTPUT  FROM   I9I3  TO  I92Q 

Of  the  total  kilowatt-hour  output  of  the  Duquesne 
Light  Company  as  shown  in  Fig.  3,  56  percent  is  dis- 
tributed for  power;  26  percent  to  street  railways;  8 
percent  for  mercantile  purposes,  4  percent  for  street 
lighting,  4  percent  for  domestic  use,  and  2  percent  for 
miscellaneous  work. 

The  industrial  and  commercial  requirements  of  the 
district,  both  those  served  by  the  Company  and  those 


May,   1921 


THE   ELECTRIC  JOURNAL 


t'-enerating  their  own  power  are  shown  m  Fig.  4.  All 
of  this  power  load  generated  by  isolated  plants  is  con- 
sidered to  be  prospective  business  for  the  Company, 
with  the  exception  of  that  generated  by  the  blast  fur- 
nace   byproduct    gases.     With    the    increased    require- 


FIG.    3 — PERCENTAGE    OF    OUTPUT    OF    DUQUESNE    LIGHT    COMP.VNY 
DEVOTED  TO  DIFFERENT  CLASSES  OF  SERVICE 

r'cnts  for  power  in  such  plants,  there  is  a  jiossibility  of 
ihe  byproduct  fuel  not  being  sufficient,  thus  necessitat- 
ii'g  the  use  of  coal  or  other  fuel.  Under  these  condi- 
Mons,  it  may  be  advisable  to  purchase  all  power  beyond 
tl-at  which  can  be  produced  by  the  use  of  waste  gases. 
Mutual  arrangements  between  the  steel  companies  and 
The  Duquesne  Light  Company,  whereby  the  latter  would 
furnish  all  power  except  that  produced  by  waste  gases, 
would  be  most  desirable  and  would  give  the  steel  com- 
I'anies  reliable  power  at  reasonable  rates  and  the  Com- 
].any  a  load  of  excellent  factor. 

Mven  where  blast  furnace  gas  is  axailable  there  are 
cases  where  the  (nirchase  of  all  power  from  a  central 
station  may  prove  of  advantage.  .\s  these  gases  pos- 
sess very  low  heat  values  and  cannot  be  transmitted  any 
great  distance  with  economy,  it  is  impossible  to  collect 
tliem  from  scattered  sources  in  one  central  location 
v.here  a  large  plant  could  be  erected.  The  cost  of  the 
generating  capacity  which  would  he  necessary  ior 
i;tilizing  this  gas  in  relatively  small  tmits  would  be  ex- 
cessive, and  refinements  of  operation  and  efficiency 
would  be  limited  in  comparison  with  that  of  such  a  sta- 
l  on  as  the  Colfa.x  Plant  of  the  Duquesne  Light  Com- 
pany, whose  sole  business  is  the  generation  and  distri- 
hution  of  electric  power. 

Referring  to  the  metals  and  metal  product:;  classi- 
lication,  by  far  the  greater  portion  of  the  isolated  plant 
load  exists  in  steam-driven  steel  rolling  mills.  The  in- 
cieased  cost  of  operation  due  tn  the  increased  price  of 
coal,  and  the  disadvantages  of  steam  drive,  as  compared 
to  central  station  motor  drive,  where  speed  regulation 
and  control  permit  greater  production  and  better  quality 
of  products,  is  generally  recognized.  The  remainder  of 
the  load  represented  in  this  classification  consists  of 
many  diversified  industries  whose  power  needs  are 
being  rapidly   supplied  by  the  Company.     This  is  due 


largely  to  keen  competition,  necessitating  the  installa- 
tion of  modern  motor  driven  equipment  in  such  fac- 
tories to  speed  up  production  and  reduce  costs  to  meet 
competitive  conditions. 

There  are  about  20000  kw  of  isolated  water  pump 
ing  stations  in  the  district.  These  consist  largely  of 
various  types  of  steam-driven  equipment,  which  should 
be  replaced  by  electric-driven  equipment,  when  the 
present  facilities  become  obsolescent  to  the  extent  of 
the  change-over  cost  being  more  than  offset  by  the 
economy  effected  b}'  the  use  of  purchased  power.  While 
it  is  realized  that  these  [ilants  have  an  extremely  high 
load  factor  and  in  most  instances  a  good  pumping 
economy,  yet  it  is  hardly  [rossible  for  this  economy  to 
equal  that  obtained  with  electric-driven  centrifugal 
[.umping  installations  supplied  with  power  by  the  large 
efficient  units  in  use  by  the  Company.  This  is  espe- 
cially true  with  installations  having  an  adequate 
leservoir  capacit}-  so  that  the  pumping  could  be  done 
during  the  off-peak  hours  of  our  system.  Such  an  ar- 
rangement would  permit  of  a  lower  rate  than  that  to 
a  power  user  requiring  continuous  service  during  the 
peak-load  period. 

To  completely  electrify  the  railroads  operating  in 
the  district,  it  is  estimated  that  approximatel)'  200  000 
kilowatts  of  capacity  will  be  required.  It  is  under- 
stood that  some  railroads  have  already  made  tentative 
plans  for  partial  electrification.  This  load  is  prospec- 
tive business  for  the  Company,  as  it  would  be  relatively 


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FIG.   4 — CLASSIFIED    POWER   REQUIREMENTS    IN   THE   PITTSBURGH 
DISTRICT 

uneconomical  to  generate  it  in  plants  bviilt  only  for  that 
])urpose,  because  of  the  lack  of  diversity  in  a  load  of 
one  character.  Such  a  load  would  be  an  advantage  to 
the  central  station,  where  there  would  be  considerable 
diversity  between  il  and  the  industrial  load  which  now 


THE   ELECTRIC  JOURNAL 


Vol.  Win,  N( 


comprises  the  larger  portion  of  the  Company's  output. 

The  present  electric  furnace  load  of  22  ouu  kilo- 
watts supplied  bv  our  Company  and  representing  eight 
percent  of  the  total  kw-hrs.  output,  is  considered  to  be 
just  the  beginning  of  the  development  expected  within 
the  next  few  years.  The  electric  furnace  has  earned  a 
permanent  place  in  the  steel  industry  for  producing  high 
grade  tool  and  alloy  steels  and  steel  castings.  It  has 
supplanted  to  a  large  extent  the  crucible  process  in  the 
production  of  tool  and  alloy  steel  due  to  its  lower  cost 
and  greater  flexibility.  The  demand-  for  these  steels  is 
constantly  increasing,  not  only  because  new  users  have 
been  found  for  them,  but  because  of  their  demonstrated 
superiority,  especially  in  the  automotive  industry,  which 
is  becoming  increasingly  dependent  upon  tool  and  alloy 
sleels. 

In  the  pnoduction  of  steel  castings,  it  has  been 
found  that,  due  to  the  intense  heat  of  the  electric  arc, 
the  absence  of  the  contaminating  eii'ects  of  the  combus- 
tion gases  and  the  reducing  atmosphere  within  the  fur- 
nace, it  is  possible  rapidly  to  melt  and  refine  a  product 
superior  to  the  highest  grade  of  casting  made  either  in 
the  open  hearth  or  crucible  furnaces.  At  the  jiresent 
t'me,  many  large  consumers  of  steel  castings  frec|uently 
specify  the  electric  steel  for  their  more  important  work, 
for  which  they  formerly  had  been  content  to  use  con- 
verter or  open  hearth  steel. 

While  the  electric  furnace  has  been  used  principally 
for  the  production  of  tool  and  alloy  steel  and  steel  cast- 


ings, it  is  becoming  more  extensively  used  in  the  pro- 
duction of  gray  iron  and  malleable  castings.  In  the 
manufacture  of  especially  sound  and  fine  castings  of 
light  and  thin  section,  it  is  a  worthy  competitor  of  the 
old  cupola  process.  The  demand  for  high  grade  iron 
castings  is  increasing,  and  the  indications  are  that  those 
made  by  the  electric  process  which,  in  many  instances, 
have  been  produced  at  a  lower  first  cost  and  with  few  er 
r(!lurns  of  defective  castings,  will  sell  for  maximun 
competitive  prices. 

To  promote  the  rapid  industrial  e.xpfmsion  of  the 
Ciistrict  by  furnishing  an  abundance  of  economical 
]iower,  the  Ducjuesne  Light  Company  has  erected  ii> 
Colfax  power  plant,  which  is  the  highest  attainment  in 
the  art  of  generating  electric  power.  This  plant  is  de- 
signed for  an  ultimate  capacity  of  300000  kw,  and  I'- 
ll cated  on  the  Allegheny  River,  about  sixteen  miles 
;iho\e  the  City  of  Pittsburgh.  Coal  is  brought  to  the 
]  lant  from  the  Company's  mine  over  its  own  railroad, 
thereby  relieving  the  congestion  of  transporting  coal  on 
the  other  railroads  in  the  district.  By  the  closing  down 
of  the  isolated  plants  in  the  district  the  railroads  will 
further  be  able  to  utilize  their  equipment  for  the  ship 
ping  of  manufactured  products.  This  will  eliminate 
iiiany  smf)ky  chimneys  in  the  district  and,  with  the  elec- 
trification of  railroads,  will  result  in  the  City  of  Pitts- 
Inirgh  being  referred  to  not  only  as  "The  Workshop  of 
the  World",  but  also  as  "The  Electrical  Workshop  of 
the  World." 


i:!:  ti^r)  1J.S>  >S'i:eo]  Coa'pocn^ 


111  i^twfir;^!! 

S.  S.  WALES 

Electrical  Engineer, 
Canu'nic  Steel  Company 


THE  interconnected  group  of  plants  of  the  United 
States  Steel  Corporation  in  the  Pittsburgh  dis- 
trict, consisting  of  Homestead  Steel  Works  and 
Carrie  Eurnaces,  Edgar  Thomson  Steel  Works  and 
Eurnaces,  and  the  National  Works  of  the  National  Tube 
Company  at  McKeesport,  make  a  power  development  of 
considerable  magnitude,  which  will  probably  never  be 
replaced  by  the  purchase  of  power  from  the  local  com- 
mercial central  stations. 

The  Carrie  Furnace  plant  is  an  integral  part  of  the 
Homestead  Steel  Works  and  so  may  be  considered  as 
one  unit.  The  plant  at  Carrie  Furnace  supplies  a  large 
amount  of  power  to  the  Homestead  Steel  Works,  in  ad- 
dition to  furnishing  about  1 1  000  kw  to  the  Universal 
Cement  Company's  plant  at  Universal,  six  miles  from 
the  furnaces. 

The  stations  at  Carrie  Eurnaces,  Edgar  Thomson 
and  Duquesne  are  based  on  the  use  of  blast  furnace 
gas^ — an  unavoidable  by-product,  which  must  be  used 
close    to    the    point    of    origin    on    account    of    its    low 


calorific  value.  For  the  purpose  of  this  article  we  can 
assume  that  for  each  ton  of  pig-iron,  by-product  gas 
containing  14000000  B.t.u.'s  of  latent  heat  will  be  pro- 
duced. Of  this  we  can  expect  30  percent  to  be  used  to 
heat  stoves,  20  percent  to  be  used  for  furnishing  the 
blast,  and  10  percent  for  miscellaneous  purposes  around 
the  blast  furnaces,  or  a  total  of  60  percent  required  ai 
the  furnaces  themselves.  We  can  safely  estimate, 
then,  that  40  percent  of  this  heat  will  be  available  for 
I'ower  iirnduction.  which,  if  all  converted  into  electric 
power  on  the  basis  of  21  000  B.t.u.'s  for  each  kilowatt 
delivered  to  the  switchboard,  would  make  266  kw-hrs. 
I'vailable  for  each  ton  of  pig-iron  produced. 

In  running  through  the  different  losses  and  addi- 
tions which  are  encountered  between  the  production  of 
cue  Ion  of  i>ig-iron  and  the  finishing  of  one  ton  of  steel, 
v>e  can  fairly  estimate  that  one  ton  of  pig-iron  pro- 
duced will  represent  one  ton  of  finished  steel  shipped. 

From  data  available  we  can  estimate  that  it  will  not 
recjuire  in  excess  of  120  kw-hrs.  per  ton  of  finished  steel 


May,  1921 


THE   ELECTRIC  JOURNAL 


223 


in  the  shape  of  sheet  bar,  small  billets,  sheared  [ilates, 
structural  steel,  rails,  etc.,  and  not  over  150  k\v  to  carry 
the  finishing  down  as  far  as  merchant  bar.  The  266 
k\v-hrs.  is  based  on  a  production  which  is  spread  over 
365  days  in  the  year,  and  the  rolling  steel  would  only 
be  distributed  over  300  days  in  the  year,  so  that  the 
power  immediately  available  at  the  time  it  is  required 
vvould  be  reduced  in  the  ratio  of  300  to  365,  which 
would  show  218  kw-hrs.  available  for  each  ton  of  ma- 
terial to  be  finished.  This  figure,  compared  with  the 
maximum  shown  above,  would  leave  68  kw-hrs.  over 
actual  requirements,  or  45  percent  surplus  to  take  care 


FIG.    I — LOC.MION   OF   POWER   PL.\NTS   AND   TK.XXSjMISSION   LINKS 

(.'f  peak  loads,  which  should  be  ample  for  the  size  of 
stations  required  by  a  completely  electrified  mill  and  the 
Itrobable  diversity  factor  which  they  would  have. 

It  will  be  seen,  therefore,  that  it  is  possible  for  a 
blast  furnace  and  steel  plant  to  be  practically  self-con- 
tained as  far  as  power  production  and  consumption  is 
concerned,  making  the  purchase  of  outside  power  un- 
necessary. 

The  present  generating  capacit}-  of  the  stations  re- 
ferred to  is  as  follows: — 

Homestead  Steel  Works   5  JSO  k\v 

Carrie  Furnaees   30  i  SO 

F:dgar  Thomson  Steel   Works  and   Furnaces   ..    11  275 

Dnqucsne  Steel  Works  and  Furnaces  28  175 

National   Tube  Works    if,  87c 

Total    TOO  825^kw 

t.if  this  tiital.   14230  kw  is  250  volt  direct-current,  and 


86  575  kw  is  generated  as  25  cycle  alternating  current 
c.t  6600  volts.  Of  the  total,  23  700  kw  is  equipped  with 
gas  engines  as  prime  movers,  15  250  kw  is  steam  engine 
driven,  and  the  remaining  61  875  kw  is  steam  turbines. 
.\s  all  of  these  stations  are  within  a  few  miles  of 
each  other,  it  was  considered  advantageous  to  tie  them 
together  so  that  they  could  support  one  another,  thus 
reducing  the  amount  of  spare  equipment  required,  and 
giving  additional  safety  in  case  of  trouble  in  any  one 
station.  The  present  transmission  lines  between 
Duquesne,  ICdgar  Thomson,  Carrie  Furnaces  and 
Homestead  consists  of  two  parallel  independent  three- 
wire  circuits,  as  shown  in  Fig.  i,  one  of  500000  circ. 
mils  and  the  other  of  400000  circ.  mils,  carried  on  steel 
towers,  steel  poles  and  wooden  poles,  as  conditions  re- 
quire, and  insulated  for  6600  volts.  Insulating  for  6600 
volts  under  these  conditions  does  not  necessarily  mean 
the  use  of  6600  volt  insulators,  and  it  has  been  found 
desirable  to  use  25  000  volt  insulators  in  many  places  on 
the  line  and  40  000  volt  insulators  in  some  exceptionally 
smoky  and  dusty  places  in  running  through  the  mills. 
Iliese  tie  lines  are  all  overhead  open  construction  with 
hare  copper  cable,  carried  on  pins  and  wooden  cross 
arms.  A  double  bus  arrangement  is  used  at  the 
Duquesne,  F.dgar  Thomson  and  Carrie  Furnace  plants 
which,  in  conjunction  with  the  two  circuit  tie  lines  and 
relays  that  are  used  between  the  stations,  forms  an  ex- 
ttemely  flexible  combination,  so  that  line  troubles  or 
other  disturbances  produce  a  minimum  interruption  of 
service. 

The  connecting  line  between  this  group  of  plants, 
and  the  National  Tube  Works  at  McKeesport  consists 
of  a  4/0  three-wire  aerial  cable,  steel  armoured  but 
without  lead  covering,  and  is  insulated  for  25000  volts, 
in  view  of  the  possibility  of  stepping  this  line  up  to 
22  000  volts  in  the  future. 

All  the  plants  referred  to  so  far  are  connected  di- 
rectly from  the  bus-bars  at  6600  volts,  25  cycle  as  gen- 
erated in  the  stations,  without  the  interposition  of  anv 
siep-up  or  step-down  transformers. 

The  line  connecting  the  Carrie  Furnace  plant  with 
the  Cement  Plant  consists  of  two  parallel  independent 
three-wire  circuits  of  No.  o  copper  wire,  carrying  25 
cycle  current  at  2t^  000  \olts  through  step-up  and  step- 
down  transformers  at  each  end  of  the  line. 


yyor  Dovotements 


DANIEL  W.  MEAU 

Consulting  Engineer 
Madison,  Wis. 


CONSIDERABLE  misunderstanding  seems  to 
exist  as  to  the  proportion  of  the  water  power  re- 
sources of  the  United  States  now  developed  and 
also  projected  under  the  new  Federal  Water  Power  Act. 
All  estimates  of  potential  water  powers  of  the  L'liited 
States  that  will  admit  of  practicable  development  must 
be  \»ery  uncertain,  first  on  account  of  the  lack  (jf  de- 
tailed knowledge  of  the  toiiograiih}-  of  the  river  \alleys 
and  (jf  information  as  to  available  dam  sites  and  conse- 
quently of  the  actual  head  that  can  be  developed;  and 
second,  because  of  the  lack  of  knowledge  of  available 
stream  flow.  For  these  reasons  such  estimates  must  be 
only  roughly  approximate,  and  until  more  detailed  in- 
lormation  is  available  it  is  suflicienth'  exact  to  estimate 
the  power  of  the  rivers  of  the  L'nited  States  at  about 
30000000  horse-power  (on  a  24-hour  basis)  and  the 
[iower  which  can  be  developed  on  the  basis  of  "the  a\er- 
age  minimum  flow  for  the  average  maximum  six 
months"  at  6oooo(X)o  h])  (on  a  J4-hour  basis).  This 
last  quantity  would  i)robably  require,  on  the  average, 
that  from  15  to  20  percent  of  the  power  be  developed 
f'dm  auxiliary  sources,  in  order  to  maintain  the  full 
power  every  da}'  and  hour  for  each  year. 

If  we  acce])!  the  figure  of  60000000  24-hour  horse- 
I  ower  as  the  probable  maximum  potential  water  power 
resources  of  the  L'nited  States  which  appears  at  all 
practicable  of  development,  we  must  appreciate  also  the 
terms  in  which  the  estimate  is  expressed  in  order  to 
comprehend  these  national  resources  fully.  Little 
power  is  used  uniformly  24-hours  per  day.  In  most 
cases  when  pow-er  is  used  for  manufacturing  purposes, 
the  maximum  load  occurs  within  the  working  day  and, 
when  used  for  general  light  and  power  purposes,  the 
maximum  load  occurs  during  the  day  and  e\'ening.  Mr. 
Philip  Torchio  estimates  the  total  steam  power  installed 
in  the  L^nited  States,  including  central  station,  manu- 
facturing, steam  railroads,  steam  vessels,  mines,  and 
quarries  at  96000000  horse-power  and  the  total  power 
output  at  145200000000  horse-power-hours  per 
annum.  This  total  output  could  be  generated  by  a 
16000000  horse-power  installation  working  uniformly 
2^ -hours  per  day  for  the  entire  year,  hence  the  actual 
load  factor  averages  about  17  percent.  Mr.  Torchio 
also  estimates  the  hydraulic  horse-power,  installed  at  the 
date  of  his  estimate,  at  8  000  000  horse-power  and  the 
hydraulic  power  output  at  29  (X)0  000  000  horse-power- 
hours,  with  a  load  factor  of  about  41.5  percent. 

It  is  probably  conservative  to  estimate  that  the 
average  water  installation  can  be  developed  to  utilize  its 
full  power  on  a  50  percent  load  factor,  and  hence  to 
conclude  that  the  present  water  power  developments  in 
the  United  States  are  utilizing  the  ultimate  hydraulic 
resources  to  only  one-half  of  their  turbine  capacity. 


At  the  beginning  of  1920  it  was  estimated  that  the 
water  power  development  in  the  United  States  was  as 
follows : — 


1      llor.s<--Power       1 
1        Developed          I 

percent  of  Total 
Development 

New  England  States.... 
Atlantic    States    

. .  1         I  506  520 

15-3 
30.1 

27-5 
1 1-3 

iS-8 

1 00.0 

Mountain  States 

. .  1         1  1 1 1  ggo- 

Total 

1                             1 

1     9823540 

In  estimating  the  undeveloped  potential  water 
(lowers  of  the  L'nited  States,  the  total  developed  power 
as  above  stated  is  commonly  subtracted  from  the  esti- 
mated total  potential  water  power  with  the  result  that 
th.e  undeveloi)ed  power  is  estimated  at  about  50000000 
horse-power.  It  will  undoubtedly  be  much  nearer  cor- 
rect if  the  developed  power  be  estimated  on  a  56  per- 
cent load  factor,  which  would  raise  the  estimate  of  un- 
developed water  ])ower  to  about  53000000  horse-power 
or,  in  greater  detail,  as  follows : — 


Potential 

Undeveloped 

Morse- 

Devel- 

1lorsc- 

Power 

oped 

Power 

\c\v  England  States.. 

I  951  000 

38.6 

I  197  750 

Atlantic   States    

9348000 

15.8 

7871580 

Central    States    

7360000 

18.3 

6  010  400 

Mountain   States    .... 

14851000 

3-9 

14  294  000 

Pacific    States    

25850000 

3- 

25  074  520 

Total  United  States 

59  360  000 

8.3 

54448220 

It  is  understood  that  the  applications  filed  under 
the  new  Federal  Water  Power  law  amount  to  13  500000 
liorse-power.  This  has  been  estimated  at  about  27  per- 
cent of  the  total  water  power  resources  of  the  United 
States.  While  information  is  not  available  as  to  the 
basis  of  these  proposed  developments,  it  is  unlikely  that 
tl-ey  will  be  developed  on  lines  greatly  different  from 
those  already  developed;  hence  they  should  be  esti- 
mated on  the  basis  of  a  50  percent  load  factor  and  at 
about  13.5  percent  of  the  total  water  power  resources  of 
the  United  States.  It  should  therefore  be  noted  that 
even  if  these  powers  .should  all  be  developed  they  woulil 
raise  the  developed  power  of  the  United  States  to  less 
than  22  percent  of  the  total  water  power  resources. 

There  is  therefore  still  available,  undeveloped 
water  power  for  which  no  applications  have  yet  been 
filed  amounting  to  about  78  percent  of  the  available 
water  resources  of  the  l'nited  Stales,  or  to  about 
47  000  000  24-hour  horse-power. 

The  development  of  these  water  power  resources  is 
(■f  great  importance  to  the  nation,  and  those  who  under- 
take judicious  developments  should  be  encouraged  in 
every  proper  way,  by  the  enactment  of  liberal  laws  and 
by  the  guarantees  of  liberal  and  at  least  reasonable  rate 
control.  These  develojiments  will  involve  the  invest- 
ment of  billions  of  dollars  in  construction,  and  addi- 
tional billions  in  collateral  industries  and  itnprovements. 


May,   1921 


THE   ELECTRIC  JOURNAL 


They  will  acconi[)lish  either  the  saving  of  millions  of 
tons  of  coal  now  annually  consumed  in  power  plants  or 
an  equivalent  saving  in  fuel  that  would  otherwise  be 
consumed.  They  will  afford  a  source  of  power  not  con- 
tingent on  strikes  or  transportation  blockades,  and 
therefore  more  dependable  and  assured. 

The  collateral  increase  in  property  values,  and  in 
population,  which  will  necessarily  accompany  these  de- 
velopments, the  conservation  of  millions  of  tons  of  fuel 
for  future  generations,  the  substantial  development  of 
the  states  and  the  immediate  localities  in  which  these 
developments  take  place  and  the  betterment  of  industrial 
;>nd  living  conditions  resulting  from  such  development 
are  public  benefits  which  will  warrant  the  most  liberal 
tieatment  of  those  who  undertake  such  projects.  To 
secure  these  developments,  their  projectors  must  be 
fssured  of  the  possibilities  of  rewards  for  their  en- 
deavors commensurate  with  the  risk  invohed  and  the 
public  must  be  made  to  realize  the  difficulties  surround- 
ing their  profitable  development. 

TABLE   I — PERCENTAGE  OF   POWER  USED,   COMPARED   WlTtl 
POTENTIAL   WATER  POWER 


Stales 

Percent 
Power 
Csed 

PereelU 

Potential 

Water  Power 

New  England 

12.8           1           2.C^S 
27.8           1           4.62 
23.4                     2.98 

6.8  3-63 
97                 700 

4.9  364 
4-5                 1-52    ■ 
3.0               29.92 

East   North   Central 

West  North  Central 

East   South   Central 

West  South  Central 

Mountain  

Pacific                       .            ... 

Total                  1 

lOO.O           1 

lOO.O                1 

Most  of  the  profit  made  in  water  power  develo]i- 
n:ents  up  to  the  present  time  has  been  through  the 
financing  of  such  properties  rather  than  in  their  owner- 
ship and  operation.  It  is  safe  to  assume  that  at  the 
present  time  there  are  few  water  power  owners  or 
owners  of  water  power  securities  that  are  making  a 
profit  even  fairly  coninieiisurate  with  the  ri--k  iin(il\ed 
by  their  investments.  On  the  other  hand,  In  secure  the 
financing  of  such  development  requires  a  degree  of 
security  and  a  possibility  of  profitable  returns  which  is 
not  cnmmon  in  the  undevelo])ed  water  power  projects  of 
today,  and  many  of  the  projects  for  which  applications 
are  now  pending  under  the  new  federal  law  will  un- 
doubtedly find  the  financing  of  the  installation  the  most 
serious  factor  to  overcome. 

One  of  the  greatest  difficulties  in  the  way  of  the 
rapid  development  of  water  powers  lies  in  the  <Iislance 
ot  the  points  of  develojiment  of  such  powers  from  the 
markets  where  power  is  needed.  Sixty-five  percent  of 
;.ll  the  power  used  in  the  United  States  is  east  of  the 
I\Iississippi  River  and  north  of  the  Ohio  River  and  the 
southern  Pennsylvania  boundary,  where  only  about  ten 
percent  of  the  potential  water  powers  are  located. 
About  73  percent  of  the  potential  water  powers  are  in 
the  Mountain  and  Pacific  States  where  only  about  ten 
percent  of  the  power  market  is  now  located. 


The  general  distribution  of  power  demand  and 
[possible  water  power  available  are  shown  in  Table  T 
which  is,  however,  somewhat  misleading,  from  the  fact 
that  many  of  the  water  powers  estimated  for  the  dis- 
tricts where  most  of  the  power  demand  is  located  are 
inaccessible  to  the  manufacturing  centers  under  present 
conditions  of  commercial  and  manufacturing  develop- 
ment and  under  the  present  developed  methods  of  power 
transmission. 

The  development  of  a  water  power  is  not  a  simple 
method  of  surely  capitalizing  the  waste  energy^  of  the 
streams  and  securing  the  returns.  The  hazards  in- 
volved, both  in  the  construction  of  such  properties  and 
in  the  contingencies  of  their  operation  and  maintenance 
are  considerable.  With  the  advent  of  electrical  trans- 
mission coupled  W'ith  the  popular  conception  that  water 
I'owers  were  always  exceedingly  profitable,  and  that  by 
means  of  such  developinents  the  waste  energy  of  water 
could  be  advantageously  turned  into  dividends,  investors 
eagerly  sought  water  power  investment.  The  expected 
results  have  seldom  been  realized  and  the  actual  results 
have  sometimes  proved  disastrous.  An  extended  list  of 
financial  catastrophes  that  have  resulted  from  this  con- 
ception of  water  power  development  could  readily  be 
made.  Foreclosures  and  sales  of  water  power  proper- 
ties have  been  common.  In  one  case,  the  investors  in 
the  bonds  of  a  water  power  company  realized  less  than 
five  percent  of  their  par  value.  In  another  case,  the 
plant  w'as  abandoned  and  disiuantled.  It  is,  of  cour>e, 
apparent  that  such  projects  were  ill-advised  and  should 
never  have  been  undertaken  or,  if  attempted,  under- 
taken on  a  more  conservative  basis ;  but  the  history  of 
every  business  is  full  of  investments  of  this  character, 
and  no  line  of  business  has  e\er  been  developed  in 
which  the  path  of  such  developments  has  not  been 
strewn  with  the  wrecks  of  ill-ad\ised  projects.  Xo 
r.jan  is,  or  can  be  allwise,  and  a  question  as  to  the  ulti- 
mate success  must  accompany  almost  ever}'  new  en- 
deavor, and  throw  a  doubt  on  the  wisdom  of  its  pro- 
jectors and  on  the  desirability  of  the  inxestment.  This 
i-  essentiallx   true  in  all  water  power  developments. 

I'ew  will  agree  with  the  statement  of  a  prominent 
water  |iow'er  engineer  before  a  committee  of  the  House 
(J!  Representati\'es  that,  "Today  the  matter  of  develop- 
ing power  from  falling  water  is  a  matter  of  absolute  en- 
gineering certainty."  Such  statements  are  misleading 
for,  while  experience  can  reduce  hazard  and  increase 
securit}',  it  can  never  olniate  the  contingencies  of  floods 
.'•nd  unf(j!'seen  physical  cnnditions  or  the  uncertainties 
V,*  costs  nf  construction  and  of  market  conditions. 

While  it  is  perfectly  true  that  the  best  engineering 
practice  in  water  power  design  has  reached  a  fairlv  liigh 
stage  of  (lexelopmeiU,  compared  with  fonuer  practice, 
i'.  is  ecpially  true  that  many  engineers  engaged  in  this 
work  ha\e  failed  to  keej)  pace  with  this  progress,  and 
n;any  designs  offered  are  open  to  serious  criticism,  as 
not  affording  a  proper  basis  for  •  adequate,  safe  and 
profitable  dexelopment. 


226 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No. 


Plans  for  large  and  important  structures  are  rarely 
devised  that  do  not  require  more  or  less  modifications 
during  construction.  Unless  this  fact  is  duly  appre- 
ciated by  the  designer,  and  liberally  allowed  for  in  the 
estimate  of  cost,  such  estimates  have  often  been  found 
more  or  less  inadequate  to  complete  the  structure.  The 
hazards  of  construction  increase  with  the  difficulties. 
When  a  structure  is  built  in  and  across  a  river,  the 
work  of  construction  is  subject  to  unusual  hazards, 
which  cannot  always  be  foreseen.  Due  to  conditions 
which  cannot  be  fully  predetermined  without  unwar- 
ranted expenses,  and  to  the  contingencies  of  flood,  the 
amount  of  investment  is  not  easily  determined  and  the 
ultimate  cost  is  frequently  greater  than  any  reasonable 
estimate  that  can  be  made. 

The  unexpected  extra  costs  of  such  developments 
due  to  unforseen  delays  is  often  serious.  The  interest 
en  bonds  must  be  met  semi-annually  or  annually  from 
their  date  of  issue ;  hence,  interest  during  construction 
and  during  the  period  of  market  development  is  an  im- 
portant item  which  is  particularly  uncertain  in  water 
power  development.  In  a  recent  development  of  this 
k:nd,  a  flood — the  most  extraordinary  that  had  occurred 
on  the  river  within  the  known  records — not  only  caused 
a  loss  of  approximately  $40000  to  the  work  under  con- 
struction, but  was  followed  by  continuous  and  unusual 
high  water  for  the  year  following,  so  that  not  more  than 
90  working  days  were  available  within  the  year.  In  the 
same  endeavor,  an  ice  jam  in  the  spring  carried  out  all 
the  trestle  and  false  works,  involving  a  loss  of  perhaps 
$10000  more.  These  casualties  created  a  delay  of  more 
than  a  year,  with  an  extra  interest  cost  of  Stoockx). 

Such  hazards  are  more  constantly  present  in  all 
classes  of  hydraulic  endeavors  than  in  those  of  almost 
any  other  kind  of  developments.  While  care  and  ex- 
perience with  water  power  projects  may  perhaps  finally 
result  in  greater  consideration  and  more  liberal  esti- 
mates, so  as  to  provide  for  contingencies  which  are 
likely  to  occur,  still  the  contingencies  exist,  and  such 
investment  will,  in  the  future  as  in  past,  be  frequently 
underestimated,  and  the  actual  costs  of  construction  will 
require  greater  investments  than  the  projectors  will 
think  jjossible,  even  when  nionc}-  is  judiciously  ex- 
pended. 

F.ven  after  a  plant  is  once  constructed,  the  contin- 
gencies arc  not  removed.  Within  the  last  few  years  a 
flood  in  one  of  our  rivers  caused  a  loss  of  about 
$30000010  a  single  development.  This  loss  resulted 
from  an  extraordinary  condition  which  could  hardly 
have  been  foreseen,  and  which  would  probably  not  have 
occurred  once  in  a  tltousand  times  under  similar  condi- 
tions. In  another  case  a  dam  was  seriously  injured  by 
a  flood  produced  by  the  destruction  of  another  dam  built 
by  a  different  engineer,  long  after  the  first  dam  was 
constructed.  The  dam  injured  possessed  sufficient 
strength  and  capacity  for  all  contingencies  of  normal 
flow  that  were  liable  to  occur,  yet  the  unexpected  de- 
struction of  another  structure  afterwards  built  above  it. 
c.nii=:°d   an   extraordinarv   condition   that   resulted   in   a 


loss  of  perhaps  $150000  and  put  the  plant  out  of  com- 
mission for  more  than  a  year. 

Numerous  instances  could  be  recited  where  either 
fundamental  defects  or  extraordinary  conditions  have 
destroyed  or  seriously  injured  dams  and  water  power 
plants  and  caused  serious  losses  to  their  owners.  Man- 
khid  is  fallible;  our  knowledge  of  the  possible  activities 
of  natural  forces  is  limited ;  the  effect  of  the  possible 
ccanbination  of  all  of  the  known  and  unknown  factors 
can  never  be  clearly  seen  or  appreciated ;  yet  these  con- 
tingencies are  ever  present,  and  must  be  considered  bv 
water  power  designers  and  investors. 

A  water  power  can  seldom  be  developed  at  a  first 
cost  which  compares  favorably  with  the  cost  of  a  plant 
developing  power  by  heat  engines.  If  a  water  power 
company  is  an  independent  concern  which  develops  its 
source  of  power  to  the  "average  minimum  for  the  aver- 
age maximum  si.x  months"  and  at  the  same  time  must 
suppl}'  the  market  demand  for  power  at  all  times,  it 
nuist  install  an  auxiliary  heat  engine  plant  to  develop 
power  at  low  water  stages.  Sometimes,  such  an  auxil- 
iary plant  must  have  a  capacity  almost  as  great  as  that 
of  the  water  power  plant  itself.  The  cost  of  siich  an 
auxiliary  power  development  must  be  added  to  the  cost 
cf  the  water  power  development. 

A  steam  plant  can  always  he  constructed  of  a  size 
proportional  to  its  prospective  market  and  the  plant  can 
be  increased  and  enlarged  as  the  market  demands,  to 
any  extent  and  without  over  investment.  A  water 
power. to  be  economically  developed  must  practically  In- 
developed  to  a  certain  capacity  regardless  of  its  market. 
Powers  on  large  rivers  can  seldom  be  developed  and 
operated  successfully  in  a  small  way.  On  a  given  river 
it  is  almost  as  expensive  to  develop  a  small  amount  of 
power  as  to  develop  the  stream  to  its  capacity.  Essen 
tially  the  same  dam  with  the  same  appurtenances  are 
necessary,  whatever  the  capacity  of  the  development. 
The  same  operating  force  will  usually  be  required 
whether  the  plant  is  fully  or  partially  loaded,  and 
whether  the  development  is  partial  or  complete.  If  the 
power  is  transmitted,  the  same  towers  required  for  :i 
certain  capacity  will  carry  twice  the  capacity  or  mor< 
equally  well.  The  completed  development  will  involve 
a  larger  power  house,  a  few  more  turbines,  generators 
and  equipment,  somewhat  larger  transmission  wires,  hut 
these  are  usually  the  only  extra  expenses  involved 
I-lence,  on  large  streams,  the  development  must  be 
sufficiently  large  to  pay,  and  can  be  made  to  pay  onl\ 
when  an  adequate  market  is  available  and  an  adequate 
load  is  secured.  The  investments  in  such  plants  are  sn 
great  that  they  can  never  be  built  except  for  a  market 
already  developed,  at  least  for  their  principal  load,  un 
less  industries  are  developed  in  connection  with  them. 
Eoth  fixed  charges  and  operating  costs  begin  at  once 
v.hen  the  plant  is  constructed,  and  interest  starts  with 
construction.  A  market  must  be  obtained  almost  im- 
mediately on  completion  of  the  development  in  order 
10  meet  exi^enses,  or  the  plant  will  go  into  bankruptcy. 
The    public,    including    all    consumers    of    power 


May,  1921 


THE  ELECTRIC  JOURNAL 


227 


I  generated  by  such  a  plant,  will  from  necessity  receive  a 
portion  of  the  benefit  from  the  use  of  such  power  from 
the  commercial  conditions  that  follow  its  development. 
As  a  rule,  a  water  power  company  must  supply  power 
to  a  market  partially,  at  least,  supplied  with  power  from 
some  other  source.  Investments  in  power  generatinj^ 
machinery  of  some  kind  have  already  been  made. 
Fixed  charges  have  already  been  incurred,  and  the 
water  power  company  finds  that  in  order  to  introduce 
its  product,  it  must  sell  power  below  the  station  cost  of 
producing  it  by  means  of  steam  plants,  and  not  on  the 
basis  of  fixed  charges  plus  operating  expenses  of  the 
i\draulic  plant.  Only  in  cases  where  the  market  de- 
\  eloped  is  entirely  new,  and  where  no  fixed  charges 
have  been  entailed  for  previous  power  plant  installa- 
tions, can  a  water  power  coriipany  hope  to  realize  from 
the  sale  of  water  power,  even  a  part  of  the  fixed  charges 
cf  the  steam  plant.  Even  under  such  conditions,  a  ma- 
; trial  reduction  must  be  made  in  order  to  induce  cus- 
:.niers  not  to  install  isolated  plants  of  their  own  for  the 
production  of  such  power,  but  to  purchase  the  power 
developed  from  the  water  power  plant. 

While  an  undeveloped  market  may  ultimately  result 
ii:  a  greater  unit  price  for  power,  the  development  ex- 
penses (unearned  dividends  on  capital  invested,  unpaid 
interest  on  securities,  and  unearned  depreciation 
charges)  will  so  increase  the  cost  of  developing  a 
profitable  business  as  to  make  the  financial  success  of 
the  project  at  least  questionable.  Therefore,  it  is  es- 
sential for  the  success  of  even  water  power  develop- 
ments of  medium  size  that  an  available  market  shall  be 
within  transmission  distance,  even  "though  the  resulting 
power  prices  will  necessarily  be  reduced. 

If  a  direct  combination  can  be  effected  between  the 
water  power  company  and  -a  steam  electric  company  al- 
ready doing  business  in  such  market,  the  steam  plant 
niay  be  utilized  as  an  auxiliar)'  to  the  water  power,  and 
the  whole  value  of  the  output  utilized  by  the  combined 
interests.  Such  a  combination  is  usually  the  only  way 
■n  which  a  reasonable  net  pi'ofit  can  be  obtained  from 
water  power  development.  The  best  results  can  be 
obtained  only  by  combination  with  an  industry  or 
market  already  developed,  in  which  the  power  can  be 
utilized  at  its  true  market  value. 

Ordinarily,  it  is  a  comparativel)'  easy  matter  for  an 
operating  industry  that  is  showing  fair  returns  on  the 
investment  to  secure  the  amount  of  money  necessaiy 
for  reasonable  expansion  or  for  its  current  business, 
the  problem  of  financing  a  corporation  whose  property 
<';nd  business  are  both  a  matter  of  future  development, 
and  necessarily  more  or  less  speculative,  is  a  very  dif- 
ferent matter.  By  "speculative"  is  meant  any  invest- 
ment dependent  for  its  success  upon  the  development 
of  a  future  productive  business  of  any  kind,  whether  it 
he  the  manufacture  of  mercantile  products  or  of  power, 
the  success  of  which  depends  upon  the  judgment  of 
men  more  or  less  familiar  with  the  business  or  expert 
ill  such  de\elopments. 


Before  a  reputable  investment  house  will  undertake 
the  financing  of  such  an  enterprise  and  endorse  it  with 
the  prestige  of  their  name  and  reputation,  guaranteed 
by  the  great  care  they  have  previously  exercised  in 
financing  such  properties,  the  project  must  be  carefully 
examined  by  experts  of  reputation,  men  who  are  of  the 
highest  ability  and  experience,  who  can  and  will  vouch 
for  the  technical  features  of  the  construction,  for  the 
expense  involved,  for  the  market  available,  for  the 
legality  of  the  enterprise  and  in  fact  for  its  probable 
complete  commercial  success.  Such  houses  will  not 
lend  their  assistance  to  a  project  of  this  kind  without 
fair  returns  both  for  themselves  and  for  their  clients. 

The  securities  issued  for  the  development  of  water 
power  properties  are  usually  bonds,  preferred  stock  and 
common  stock. 

Bonds  and  preferred  slock  represent  the  actual 
cash  investment,  and  common  stock  represents  the 
speculative  element  or  prospective  profits  over  and 
above  the  market  cost  of  money.  The  security  of 
bonds  is  increased  when  they  represent  only  a  part  of 
the  actual  investment  and  when  there  is  an  equity  re- 
presented by  an  actual  cash  investment,  which  may  be 
in  the  form  of  preferred  or  common  stock.  The  public 
will  not  be  induced  to  invest  in  such  bonds  at  only  a 
tooderate  rate  of  interest  without  some  form  of  stock 
bonus ;  that  is,  without  a  share  in  the  prospective  profits. 

If  a  stock  bonus  can  be  obtained  with  such  a  bond, 
!t  will  give  the  purchaser  a  chance  not  only  of  increased 
return  but  of  increased  capital  value,  and  such  an  in- 
vestment at  once  becomes  more  attractive.  On  the 
other  hand,  a  rate  of  interest  on  bonds  issued  on  specu- 
lative industries  sufficiently  high  to  induce  the  public 
Ic  purchase  such  securities,  may  be  fatal  to  the  success 
of  the  project. 

Interest  on  bonds  must  be  met  promptly  each  in- 
terest day  to  avoid  foreclosures,  while  stock  must  await 
actual  earnings  for  its  dividends.  On  account  of  the 
necessan'  payment  of  interest  on  bonds,  many  corpora- 
tions have  found  it  impossible,  in  the  face  of  unexpected 
difficulties  and  delays  in  construction,  and  the  delay  in 
developing  a  market,  to  meet  fixed  charges  and  operat- 
ing expenses,  and  end  in  failures  when,  if  they  could 
have  been  financed  with  fewer  bonds,  or  bonds  at  a 
lower  rate  of  interest,  and  thus  been  able  to  delay  divi- 
dends, they  would  have  been  able  to  survive  and  have 
been  ultimately  successful. 

Common  stocks  always  represent  the  speculative 
feature  of  an  investment,  even  when  fully  paid  at  par 
value.  They  are  sometimes  the  only  securities  issued 
and  share  in  the  net  profit  of  the  venture.  While  they 
are  always  junior  to  preferred  stocks  and  bonds,  they 
represent,  through  their  majority  holders,  the  business 
management  of  the  project. 

The  great  advantage  to  a  company  of  capital  raised 
from  stock  is  due  to  the  consequent  reduction  in  fixed 
interest  charges.  The  development  of  a  marke* 
commonh'    takes   a    considerable   period,   and    unless   a 


228 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No. 


company  can  earn  at  once  fixed  charges  and  operating 
expenses,  a  considerable  amount  of  extra  capital  must 
be  provided  above  the  cost  of  construction  to  carry  the 
venture  beyond  this  period  and  place  it  on  an  earning 
basis. 

In  the  case  of  water  developments,  bonds  bearing 
five  or  six  percent  interest  cannot,  even  under  normal 
conditions,  be  made  acceptable  to  the  purchaser  except 
ai  a  large  discount,  or  by  a  gratuitous  distribution  of 
junior  securities  representing  the  speculative  side  of  the 
project.  Such  bonds  can,  however,  usually  be  sold  at  a 
comparatively  low  discount  if,  in  addition,  the  buyer  re- 
ceives a  junior  security  which  may  possess  a  value  and 
an  earning  capacity,  if  the  project  is  successful. 

Take  for  example,  a  water  ])ower  project  financed 
on  this  basis,  where  the  cost  of  construction  and  financ- 
ing will  be  approximately  two  million  dollars.  If,  in 
addition  to  the  bonds  amounting  to  this  total  sum  and 
bearing,  say,  five  percent  interest,  a  speculative  stock 
(which  represents  prospective  profits,  or  water  power 
rights  and  privileges)  be  also  issued  in  the  same  amount, 
investors  will  often  take  such  bonds  or  securities  at  a 
reasonable  price  from  a  responsible  and  experienced 
financial  house,  if  they  also  receive  as  a  bonus  say  50 
percent  of  speculative  stock.  Where  care  had  been 
taken,  the  bonds  may  be  a  reasonably  safe  investment. 
If  the  junior  securities  or  stock  should  ultimately  pay 
ten  percent,  the  net  result  to  the  bond  purchaser  would 
be  ten  percent  on  the  actual  total  investment,  which  is 
certainly  no  greater  return  than  .should  be  earned  by 
lond  holders  in  such  a  hazardous  investment. 

The  projectors  of  the  scheme,  or  the  parent  com- 
pany, usually  base  their  entire  hope  of  reward  for  their 
endeavors  in  such  projects,  on  such  portions  of  the 
stock  as  they  are  able  to  reserve  from  the  cost  of  financ- 
ing. They  borrow  the  capital  on  their  property  and 
credit  and,  with  the  bonds  representing  a  first  lien  and 
fixed  returns,  they  give  such  pro])ortion  of  the  slock  as 
the  market  demands. 

If  the  proiectors,  or  the  stockholders  of  the  parent 
company,  make  an  actual  investment  in  the  junior 
securities  or  stock,  thus  placing  the  primary  securities 
or.  a  sounder  basis  by  virtue  of  an  ecpiity  in  the  work  of 
30  percent  or  more,  the  primary  securities  or  bonds  can 
sometimes  be  .sold  at  a  low  discount  without  a  stock 
tonus.  In  such  a  case,  however,  the  stockholders  have 
invested  their  money  in  a  security  which  is  secondary 
to  the  bonds  issued  and  which  involves  most  of  the  risk. 
Such  an  investment  will  not  be  made  without  a  reason- 
able assurance  that  the  returns  will  be  large.  In  either 
words,  on  the  basis  of  a  two  million  dollar  investment, 
if  one  million  is  paid  from  bonds  and  one  million  from 
stock,  under  present  conditions  it  would  be  practically 
impossible  to  secure  investors  in  the  original  stock  of 
the  company,  unless  at  least  15  percent  can  reasonably 
be  anticipated  on  the  entire  investment,  in  which  case 
the  larger  earnings  would  be  secured  by  the  owners  of 
stock,  who  have  risked  their  money  practically  without 


security.  To  effect  this  result,  it  would  be  necessary  to 
issue  stock  to  the  amount  of  two  million  dollars  and  sell 
it  on  a  paid-up  basis  of  fifty  cents  on  the  dollar.  The 
stockholder  would  anticipate  an  ultimate  increase  in  the 
value  of  his  holdings  and  a  large  return  commensurate 
with  his  extra  risks.  A  large  return  under  such  condi- 
tions must  be  possible,  for  the  stockholder's  propertv  is 
the  guarantee  of  the  bonds  which  must  be  protected 
first,  both  in  interest  and  principal.  Here  again,  the  , 
total  earnings  of  the  plant,  if  successful,  would  show 
15  percent  on  the  investment.  Unless  actual  prospects 
of  such  earnings  are  considered  as  fairly  assured,  a 
de\  elopment  along  these  lines  is  impossible. 

In  the  first  instance  cited,  the  purchaser  of  the 
primary  securities  purchases  what  he  believes  to  be  a 
fairly  safe  investment,  with  the  incentive  of  a  certain 
;:mount  of  bonus  stock  which  he  hopes  and  believes  will 
net  him  an  additional  return  rather  larger  than  he  can 
secure  from  any  other  line  of  investment;  and  when 
such  bonds  are  purchased  from  reliable  investment 
houses  who  have  made  a  specialty  of  certain  lines  of  in- 
vestment, and  hence,  have  had  long  and  valuable  experi- 
ence in  a  given  line,  the  purchaser  of  such  securities 
r.iay  receive  some  additional  value  besides  his  invest- 
ment in  the  bonds  of  the  company. 

It  is  almost  impossible  at  the  present  time,  except 
under  unusually  favorable  conditions,  to  build  a  two 
million  dollar  water  power  plant,  or  to  develop  almost 
any  similar  industry,  by  the  issue  of  one  million  dollars 
in  bonds  and  one  million  dollars  in  stock,  to  be  sold  at 
their  par  value.  There  are  few  investors  who  can  come 
into  close  contact  with  the  management  of  such  ])ro[)er 
ties  as  to  make  them  feel  assured  that  they  will  ulti- 
mately secure  a  suitable  return  on  their  stock;  and  in- 
vestors who  have  not  the  knowledge  or  opportunity  to 
assure  themselves  of  the  probable  prospects  of  the  in- 
vestment, must  depend  upon  the  reputation  (if  the  in 
vestment  house,  the  [nojectors  of  the  scheme,  or  the 
engineer  on  whose  judgment  such  securities  are  pur- 
chased ;  and  such  investors  are  not  satisfied  to  take  un- 
certain risks  without  prospects  of  large  returns. 

Fifteen  percent  on  the  total  investment  in  a  water 
power  ]iroject  is  not  more  than  a  sufficient  return  when 
the  risks  in  development  maintenance  and  market  are 
considered,  and  if  the  stockholders  furnish  an  ec|uit\  to 
the  holders  of  bonds  issued  for  only  a  ])ortion  of  the 
cost,  such  stockholders  who  have  taken  the  additional 
risk  .should  be  able  to  secure  all  of  such  returns  on  the 
total  investment  as  are  not  required  for  the  payment  of 
lond  interests. 

Any  of  the  above  mentioned  methods  for  financins; 
water  ])ower  industries  by  the  issue  of  speculative  stdck. 
at  less  than  par,  and  which,  when  honestly  carried  (nil 
are  morally  unobjectionable,  are  entirely  impossible 
under  the  present  restrictions  in  most  states  for  any 
water  power  comjjany  that  must  operate  as  a  public 
utility.  Under  the  state  laws,  bonds  can  often  be  .sold 
a-   a  price  as  low  as  -JS  percent,  but  stock  in  a  public 


M 


ay,   1 92 1 


THE   F.LF.CTRIC  JOURNAL 


220 


utility — the  owners  of  which  must  take  ]iraclicaily  all 
the  risk  in  any  speculative  project — must  he  sold  at  i)ar. 
Tlie  ideas  of  the  puhlic,  and  especially  of  lesjislators 
and  public  officials,  must  chanjje  material!)'  if  the  un- 
developed water  powers  of  the  country  are  to  he  de- 
\  eloped  rapidlx'.  The  jiuhlic  interest  should  be  con- 
served, but  pri\;ite  interests  must  also  be  protected.  As 
T  rule,  the  \ery  success  of  a  |iroject  answers  the  ([ues- 
tion  as  tn  whether  or  not  it  is  for  the  ]>uhlic  fi'ood  ;  for 


it  appears  that  a  man,  who  makes  two  blades  of  grass 
i^row  where  one  grew  before,  has  performed  an  act  no 
less  beneficial  to  the  public,  the  state  and  the  nation  if 
he  reaps  and  h;ir\ests  his  grass  and  sells  it  at  a  profit  to 
himself.  No  ni;ui  w  ill  lake  part  in  water  ])ow^er  develop- 
i",ent  without  the  iKipc  of  an  adecpiate  reward,  and  when 
the  ho])e  of  such  a  reward  is  removed,  de\elo])ment  will 
iialurallv  cease. 


Of  iiio  r.olfn.K  GeM:;rat'mg  .Stntjosi  ©f  ihe  J^'iijiKSiV.)  'JglU  CoLnpany 

M     E.   SKINNER 

Trans t'ormcr  Engineer, 
Westinghouse  Electrical  &  Mfg.  Company 

THIC  main  [lower  transformers  for  stejiping  up  the      some  transformers  built  pre\  ioush-  of  much  lower  rat- 
voltage  from  that  of  the  generators  at  Colfax  to      ing  and  f(n-  service  on  lines  of  the  same  voltage, 
that  of  the  line  have  a  rated  capacity  greater  than  Power  is  generated  at  11  500  volts,  three-phase,  60 

any  single-|)hase,  two-w  inding  transformers  heretofore  cycles  and  is  stepped  up  through  the  transformers  to 
constructed.  The  rating  of  each  transformer  is  23600  66000  volts  at  the  present  time  and  later  will  be  raised 
kv-a,  giving  a  bank  capacity  of  70800  kv-a  corresjiond-  to  132000  volts.  The  generator  voltage  will  be  varied 
ing  to  the  generator  rating  of  60000  kw  at  85  |)ercent  from  as  low  as  1 1  000  to  as  high  as  12000  vcjlts 
power-factor.  The  initial  installation  consists  of  one  and  the  transformers  are  designed  to  deliver  full  rating 
60000  kw,  three  unit  turbogenerator  and  four  main  at  any  voltage  between  these  limits.  No  taps  are  pro- 
vided on  the  low-voltage  side,  so  that  the  high  \-oltage 
developed  will  vary  directly  with  the  generator  xoltage. 
The  hank  is  Cdunected  delta  on  the  low -\  c)li,i<re  side  and 


■^n.ATID.N     l\     !■( 


FIG.    I^HIGH    VOLT,\GE    IK.VXS- 
FOR.MF.R   COIL 


2 — LOW    VOLT.\GK    TR.\NS 
FORMER     COIL 


transformers.  The  extra  tranvformer  will  serve  as  a 
si)are  for  both  the  first  and  the  .second  bank  which  is 
to  follow.  In  spite  of  the  large  capacity  of  these  units, 
their  physical  dimensions  are  not  greatlv  in  excess  of 


star  on  the  high  voltage,  so  that  the  actual  voltage  ratio 
ot' each  transformer  is  1 1  500  to  38  1 00/ 76)  _>u(  >  xolts. 
Full  capacity  taps  are  provided  in  the  high-xdltage 
winding  for  dropping  the  voltage  a  total  of  approxi- 
mately 10  percent  in  four  equal  stejis  on  the  series  con- 
nection and  ten  [lercent  in  two  ecpial  steps  on  the  paral- 


230 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII.  No. 


lei  connection.     The  transformers  are  of  the  shell  form 
of  construction  and  are  oil-insulated  water-cooled. 

The  winding  consists  of  a  number  of  rectangular 
pancake  coils.  Fig.  i  shows  one  of  the  high-voltage 
coils  with  the  ventilating  strips  in  place  and  Fig.  2  one 
of  the  low-voltage  coils.     The  high-voltage  conductor 


FIG.  4— DI.-\CR.\M   FOR  CONNEC-  FIG.    5 — MOUNTING    OF    HIGH- 

TIONS    OF    THE    HIGH-VOLT.AGE  VOLT.ACE  TER.\riN.M.S 

WINDING 

The  connections  are  given 
in  Table  i. 

is  made  up  of  three  bare  copper  straps  in  parallel.  The 
three  straps  are  taped  with  several  layers  of  treated 
cloth  tape,  to  insulate  the  individual  turns.  The  insula- 
tion between  turns  is  reinforced  toward  the  ends  of  the 
winding  by  spacing  the  insulated  conductors  apart  by 
means  of  fullerboard  strips  run  into  the  coil  while  it  is 


is  wound  of  a  number  of  double-cotton  covered  wires  in 
parallel.  The  turns  are  spaced  apart  by  means  of 
fullerboard  strips,  as  in  the  high-voltage  coils.  The 
low-voltage  coils  are  among  the  largest  ever  manufac- 
tured, being  almost  nine  feet  in  length.     The  high  and 

TABLE— I— SINGLE-PHASE  AND  THREE-PHASE  STAR 

OR  DELTA  HIGH  VOLTAGE — DELTA  LOW 

VOLTAGE  CONNECTIONS 


Winding 

Volts 

Connect 

'                     peres 
Star      1    Delta 

High 
Voltage 

1                                 1 
132  000    i   76  210         310   16  to  7,  4  to     5,  3  to     2 
12§  700    1   74  305         318    |6  to  7,  3  to     5,  8  to     9 
12.5  400   1   72  400   |      326   16  to  7,  3  to     5,  8  to  10 
122  100   1   70  495   1      335    16  to  7,  2  to     5.  8  to  10 
118  800    1   68  590   j      344    16  to  7,  2  to     .">.  8  to  11 
6(i  000    1   38  105    1      620    U  to  7,  6  to  12,  4  to     5.  8  to     9 
62  700       36  200    1      652    11  to  7,  6  to  12,  3  to     5,  8  to  10 
59  400    1   34  295   |      688    il  to  7,  6  to  12,  2  to     5,  8  to  11 

Low 
Voltage 

1                   1 

i   11  500    |2  050 

1                   1 

low-voltage  coils  are  assembled  into  groups.  The  in- 
sulation between  coils  within  the  group  consists  of 
channels  over  the  straight  sides  of  the  coils,  and  washers 
of  the  same  general  shape  as  the  coils  themselves.  \'en- 
tilating  ducts  are  located  on  at  least  one  side  of  every 
coil.  They  are  obtained  by  spacing  the  washer  from  the 
coil  by  means  of  fullerboard  strips.  The  wavy  shape 
of  these  strips,  as  shown  in  Figs,  i  and  2,  serves  the 
double  purpose  of  supporting  every  conductor  at  fre- 
quent intervals  and  of  causing  the  cooling  oil  to  pass 
back  and   forth  over  the  surface  of  the   coil,   so  that 


FIG.  6 — ASSE.MlU.tU 


JILS  .VMl  IXSL  L.MIO.V    I.N    I'l 
nUILDING   OF   THE   CORE 


:v.  RE.\nV  FOR  THE 


being  wound.     The  tapering  of  the  insulation  is  quite 
clearly  .shown  in  Fig.  i. 

In  order  to  facilitate  winding,  the  low-voltage  cir- 
cuit was  divided  into  two  paralleled  sections.     Each  coil 


PIP     7_DETAIL   VIEW   OF  DI.\GONAL  CROSS   BRACING 

(.very  conductor  is  cooled.  The  spacing  strips  are  held 
in  place  by  attaching  them  to  the  washers  at  their  ex- 
tremities and  by  fastening  them  to  micarta  cleats  at  <^'-e- 
c|uent  intervals   so  as   to   maintain   a   uniform   spacing. 


May,  192 1 


THE    ELECTRIC  JOi'RXAL 


-.^1 


At  the  corners  of  the  coils,  special  ventilated  niicarta 
spacers  are  used  to  support  the  turns  more  thorDu.iihl}- 
a<  this  point  and  to  help  direct  the  flow  of  the  oil. 

Each  group  of  coils  is  then  boxed  in  by  means  of 
fullerboard  angles  and  washers  and  is  banded  to- 
gether with  stout  webbing.  The  assembly  of  the  coils 
r.nd  insulation  is  completed  by  stacking  the  groups  one 
on  top  of  the  other,  alternating  high-voltage  with  low- 
voltage  to  obtain  the  proper  interlacing.  The  boxing  on 
each  group  serves  to  insulate  each  winding  from  the 
other  winding  and  from  the  core  which  is  to  he  Iniilt 
into  this  opening  in  the  center  of  the  coils. 

■  The  completed  assembh'  of  the  coils  and  insulation 
is  shown  in  Fig.  3.  As  will  be  noticed,  certain  of  the 
vvashers  are  extended  to  form  supports  for  the 
terminals.  These  extensions  or  bridges,  as  they  are 
called,  allow  the  complete  assembly  of  the  terminals 
before  the  building  of  the  core  is  commenced,  and  pro- 
vide a  solid  support  for  the  terminals  which  is  entirely- 
free  from  rounded  parts.     In  order  to  avoid  the  need 


position  in  the  lower  frame  ready  for  the  building  of 
tlie  core.  The  punchings  themselves  are  from  high 
giade  silicon  steel  specially  treated  to  improve  its  mag- 
netic   characteristics,     (twins'   to    the    hisjh-xoltaee   de- 


ne. 8— r.L'.MWS  PUOTKCTIXG  COOLI.NG  COII.S 

To  minimize  the  danger  of  damaging  Ihe  coils   while   the 
transformer  is  being  tanked  or  nntanked. 

of  inspecting  the  high-voltage  line  lead  connec- 
tions, which  of  necessity  must  be  located  so  far  below 
the  surface  of  the  oil  as  to  be  rather  difficult  of  access, 
the  high-voltage  lead  is  made  continuous  from  the  coil 
to  the  outer  end  of  the  high-voltage  bushing.  This  ex- 
plains the  coil  (]f  cable  in  each  of  the  outer  high-voltage 
groups.  In  this  particular  instance,  this  construction 
was  complicated  b\-  the  series-parallel  connection  on  the 
lugh-voltage  winding.  This  was  taken  care  of  by  using 
a  number  of  cables  in  parallel  for  the  line  leads.  One- 
half  the  total  number  of  cables  used  are  sweated  di- 
rectly to  the  coil  lead  while  the  other  half  are  connected 
to  the  outer  of  four  terminals  immediately  abo^-e  the 
line  lead  as  shown  in  Fig.  5.  When  the  windings  are 
connected  in  series,  only  one-half  the  cables  in  each  lead 
is  carrying  current,  hut  when  in  parallel  they  are  all 
active.  A  diagram  of  the  connections  is  shown  in 
Fi§--  4, 

rig.  6  shows  the  assembled  coils  and  insulation  in 


Fli;,    () — niGU-VOLT.VGE    Fl.E.XlllI.E    CONNKCTOK 

veloped  per  inch  of  punchings,  the  laminations  were 
given  a  special  treatment  in  addition  to  the  regular 
enameling,  in  order  to  keep  the  eddy  current  losses  to  a 
jiiinimum.  In  fact,  all  through  the  design  of  these  trans- 
formers, special  features  have  been  introduced  with  the 
idea  of  carrying  the  efficiency  and  reliability  to  the 
h:ghest  limits  attainable  commercially.  The  heavy 
structural  steel  frames  which  carry  the  weight  of  the 
tiansformers  and  clamp  the  core  offer  a  magnetic  path 
which  parallels  the  core  punchings  almost  all  the  way 
around  the  circuit.  In  order  to  keep  stray  flux  and  the 
resulting  stray  losses  out  of  these  frames,  the  core 
punchings  are  separated  from  the  frames  by  wooden 
blocks.  For  the  same  reason  the  T-beams  which  pass 
through  the  coils  at  the  top  and  bottom  of  the  core  are 
made  of  phosphor-bronze  instead  of  structural  steel. 

As  might  be  expected  in  a  unit  which  handles  so 
much  energy  in  such 
a  limited  space,  hea\  \ 
mechanical  stresses 
are  unavoidable.  The 
rugged  and  nia-^si\e 
a]ii)earance  of  t  li  e 
transformer  is  nuile 
evidence  of  the  way 
in  which  these  de- 
structive forces  are 
checked  at  e \  e  r  y 
point. 

The  forces  in  a 
transformer  are 
primaril}-  d  n  c  t  o 
short-circuils.  The 
hea\\'  currents  drawn 
at  such  times  cause 
severe  stresses  of  re- 
pulsion    between    the  "°-  i^^i-ong      diswnce 

THERMOMETER 

primary   and     second-       For   monnting  on   the   side   of   the 
arv    windino's        In    a  transformer   compartment.   The   l)nlb 
''^"  is    inserted    directly'    in    one    of    the 

shell-type  t  r  a  n  s  -  heating  coils  on  the  low-voltage 
former,  the  only  por-  terminal  hoard. 

tioii  of  the  coil.-  which  is  not  braced  by  the 
core  is  the  extension  of  the  coils  at  top  and  bottom.  In 
these  transformers,  the  ends  are  braced  by  placing  two 
ihick    boiler   plates   against   the    insulation    adjacent    to 


DI.'XL-TYl^E 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No. 


them  and  tying  the  plates  together  with  heavy  steel  tie 
lods.  The  stresses  of  repulsion  between  primary  and 
secondary    act    along    the    lines    joining    the    electrical 


FIG.    II — CIRRFXT  TRANSFORMERS  A.Nl)   HEATIN'G  COII-S    MOIN'TF.D  ON 
THE  LOW  VOLTAGE  TERMINAL  BOARIl. 

centers  of  adjacent  groups  of  primary  and  secondary 
coils.  If  all  the  electrical  centers  lie  along  a  horizontal 
line,  the  stress  will  be  entirely  repulsion  between  the 
various  groups.  If,  however,  due  to  manufacturing 
limitations,  the  electrical  centers  do 
not  line  u]),  there  will  exist  a  ver-  ^ 

tical    component    of    force    tentling  IJJ^ 

to  slide  the  |irim;.ry   coils  ])ast  the  j^ 

secondary  coils.  The  phosphor 
bronze  T-beams  placed  in  the  ends 
of  the  coil  opening  are  spread 
a])art  by  means  of  the  large 
spreader  liolts  in  order  to  brace 
against  this  vertical  stress.  The\ 
serve  a  further  ]iurpose  in  that 
the  weight  of  the  coils  and  insula- 
tion is  transmitted  through  the 
spreader  holts  t(j  the  lower  end 
frame,  com])letely  eliminating  any 
])ossibility  of  sag  in  the  ])unchings. 

Ai)pai"atus  often  receives  \er\' 
severe  abuse  in  shipment.  The 
stresses  incident  to  being  shunted 
around  while  in  transit  may  be  of 
considerable  magnitude  and  are 
often  of  an  entirelx'  different 
character  than  those  the  machine 
is  to  be  called  upon  to  re;'.>t  in  its 
operation.  In  order  to  guard 
against  possible  distortion  due  to 
forces  of  this  kind,  these  trans- 
formers are  provided  with  heavy 
diagonal  cross  braces  betw een  the  l"'''^^''  '°  ''"  '''^  t=*"k 
upper  and  lower  end  frames.  Fig.  7  shows  a  detail 
view  of  the  bracing. 

The  mechanical  design  of  such  a  large  transformer 
presents  many  items  of  interest.  The  heavy  boiler  plate 
tank  is  welded  and  is  provided  with  a  heavy  angle  rim 


to  stiffen  it.  Four  hooks  are  provided  near  the  top  for 
handling  the  complete  unit.  The  cover  is  of  flat  boiler 
plate.  A  structural  steel  base  is  arranged  to  stiffen  and 
reinforce  the  bottom  and  to  transmit  the  stresses  to  the 
tank  walls  when  the  transformer  is  lifted.  The  base  is 
provided  with  roller  bearing  wheels  for  rolling  the 
transformer  on  a  track.  The  cooling  coils  are  con- 
structed of  seamless  copper  tubing.  All  joints  in  the 
tubing  are  brazed.  The  cooling  coil  is  permanentlv 
mounted  inside  the  tank,  as  the  opening  inside  the  cool- 
ing coil  is  large  enough  to  pass  the  transformer  without 
disturbing  the  coil.  The  cooling  system  is  arranged  to 
drain  by  gravity  in  case  the  water  supply  is  shut  off. 
Guards  are  placed  over  the  cooling  coil  at  the  points 
where  the  transformer  comes  nearest  to  it,  as  shown  in 
Fig.  8,  in  order  to  minimize  the  danger  of  damaging  the 
coils  while  the  transformer  is  being  tanked  or  un- 
tanked. 

To  carry  the  heavy  low-voltage  leads  through  the 
cover,  it  was  necessary  to  use  four  bushings,  two  leads 
being  connected  in  parallel  outside  of  the  transformer. 
Although  the  transformers  are  to  be  located  indoors  at 
the  present  time,  they  are  constructed  for  outdoor  ser- 
\  ice.     The  high-voltage  bushings  are  of  the  condenser 


'..    12-2}   600   KV-A   SlNCLE-l'IlASE   TR.VXSFOR.MERS 

The  htieht  to  lip  of  hiph-voltagc  bushing  is  23  ft.  Over  5200  gallons  of  oil  arc  re- 
The  complete  transformer,  filled  with  oil,  \vci.ghs  63  tons. 

tvpe  and  are  suitable  for  ultimate  operation  at  132000 
volts. 

Wherever  heavy  leads  attach  to  a  bushing,  it  should 
be  relieved  of  the  strains  incident  to  carrying  the 
weight,  and  incident  to  the  expansion  and  contraction 


.May,   19J1 


THE   ELECTRIC  JOURNAL 


233 


(1"  the  lead.  This  rehef  is  provided  by  means  of  brush 
copper  connections  between  the  transformer  terminals 
and  the  station  wiring.  The  high-voltage  connector, 
v. hich  is  adapted  for  1.5  in.  copper  tubing  is  shown  in 

rig.  9. 

The  great  size  of  these  transformers  and  tlie  im- 
[.(jrtant  position  they  occupy  in  the  transmission  s\stem 
warrants  special  precautions  for  protecting  them  and 
operating  them  intelligently,  I'y  means  of  temperature 
indicating  dexices.  the  hottest  si)ot  temperature  of  the 
windings  will  be  >h(i\\n  continuously,  both  on  the  main 
switchboard  and  im  the  (juter  wall  of  the  transformer 
t<>mi)artment.  I'mlli  indicators  operate  on  the  same 
princi])le.  A  current  transformer  oxer  one  of  the  low- 
\oltage  leads  sujiplies  a  small  heating  coil  with  a  cur- 
rent always  pro])ortional  to  the  load  current  flowing  in 
tlie  main  transformer  windings.  The  heating  coil  is  de- 
signefl  to  generate  and  dissipate  heat  at  the  same  rate 
::-  the  m.ain  windings.  Its  tem|)erature  is  alwaxs 
,:,ieater  than  that  of  the  hottest  oil  in  which  it  is  im- 
mersed by  the  same  amciunt  as  the  main  winding  tem- 
perature is  greater  than  that  of  the  oil  adiacent  to  it, 
'llie  temperature  within  the  heating  coil,  therefore,  is 
Tilways  the  same  as  that  of  the  liottest  portion  of  the 
inain  winding.  The  sw  itchI:)oar(l  mounted  indicator 
pleasures  the  temperature  within  the  small  coil  bv  meas- 
uring the  change  in  the  resistance  of  a  resistance  ele- 
ment embedded  w  ithin  the  coil.  A  Wheatstone  bridge 
method  is  used,  the  xollmeler  reading  the  unbalance  of 
the   bridge   being  calibr.ated   in    degrees   C,     Energ)'   is 


supplied  to  the  bridge  from  a  125  \olt  direct-current 
circuit.  The  indicator,  which  is  mounted  on  the  side 
of  the  transformer  compartment,  consists  of  a  long  dis- 
tance dial-t\pe  thermometer,  whose  bulb  is  inserted  di- 
rectly in  one  of  the  heating  coils.  This  type  of  thermo- 
r.ieter  is  sh(jw  n  in  Fig.  10.  Fig.  11  shows  the  details 
of  the  current  transformers  and  the  heating  coils 
mounted  on  the  low-voltage  terminal  board. 

With  an  accurate  indication  of  the  hottest  tempera- 
ture of  the  windings  of  the  transformer  available  at 
al!  times,  the  rating  of  the  transformer  becomes 
nominal.  The  load  may  be  controlled  to  keep  the  trans- 
lormer  operating  at  its  maximum  safe  operating  tem- 
perature when  the  temperature  of  the  cooling  water  de- 
ciea.ses,  so  as  to  utilize  fully  the  increase  in  capacity 
made  available  in  this  way.  If  water  is  expensive  and 
it  is  not  convenient  to  adjust  the  load,  the  amount  of 
cooling  water  may  be  considerably  decreased  when  the 
load  is  light.  In  either  scheme  of  operation  the  tem- 
perature indicator  is  the  guide.  The  indicator  mounted 
on  the  outside  of  the  transformer  compartment  is  pro- 
\ided  with  alarm  contacts  so  that  a  bell  or  lamp  alarm 
may  be  operated  in  case  anything  goes  wrong. 

In  spite  of  the  relatively  small  size  of  the  trans- 
formers in  comi)arison  with  the  amount  of  power 
handled,  they  are  among  the  most  efficient  ever  built. 
At  all  loads  between  one-half  and  full  load  the  efificiency 
is  over  99  percent  and  at  full  load  it  is  slightly  under 
99.1  percent. 


■lisiij:  'kilnnce  Sv^toin^ 


F.  C.  CHAMBERS 

President 
Des  Moines  City  Ry.  Co 


THE  problem  of  maintaining  constant  tem[ieratui-e 
boiler  feed  water,  regardless  of  li>a(l  and 
irregular  rates  of  feeding,  is  of  the  greatest  eco- 
nomic importance  in  the  operation  of  a  power  jiiant.  If 
boiler  feed  water  can  be  maintained  at  apprnximateh' 
-'12  degrees,  before  going  to  the  boiler  or  economizer, 
the  maximum  steaming  capacity  of  the  boiler  plant  can 
be  realized.  High  feed  water  temperature  al>o  reduces 
the  amount  of  disolved  :iir  in  the  feed  water,  which  has 
a  marked  effect  u[)on  the  corrosi(jn  of  drums,  headers 
and  tubes  in  the  boiler.  lun-thermore,  the  reduction  in 
the  amount  of  di.soKed  air  and  non-condensable  gases 
contained  in  the  water  re<luces  the  duty  on  the  con- 
denser air  pump,  lliereh\   !^i\  nig  a  lietter  \acuuni. 

Several  methods  of  maintaining  constant  feed 
water  temperatures  have  been  proposed,  but  most  of 
them  are  mere  approximations.  Thev  secure  the  de- 
sire<l   result  only  at  certain   points  on  the  load  curve. 

:Mr:THons  of  auxiliary  drive 
Stcan:    Dnz'tvi    .lii.viliarics — .Steam    driven    auxil- 
iaries   have    been    used    in    .some    stations    entirelv,    ex- 
hausting into  the  feed  water  heaters.     These  are  open 


J.  M.  DRABELLE 

1  Mech.  and  tilcc.  Kiig. 

Iowa  Railway  S:  I.igtit  Cu. 

to  the  objection  that  they  deliver  practically  a  constant 
quantity  of  steam  to  the  heater,  without  regard  to  the 
load  on  the  prime  movers.  Consequently,  if  sufficient 
sieam  is  supplied  for  the  maximum  load  condition  of 
the  station,  large  quantities  of  steam  are  wasted  at 
light  lo.ads.  Furthermore,  the  amount  of  steam  re- 
quired in  the  healer  \aries,  due- to  irregularities  in  feed- 
ing water  into  the  boiler.  In  other  words,  the  station 
with  entirely  steam  driven  auxiliaries  would  have  its 
heat  balance  at  hut  one  ]K)int. 

Mixed  Steam  and  F.lcrtrically-Driven  Auxiliaries — 
This  is  an  attempt  to  balance  conditions  appro.ximately 
a;  all  times.  It  depends  on  close  observation  by  the  op- 
erating force  as  to  the  temperature  of  the  feed  water 
and  a  constant  cliaii,t;ing  from  steam  to  electric  drive  in 
order  to  a\-oid  either  a  waste  of  steam  from  the  relief 
xaKe  of  the  heater,  or  low  temperatures  of  boiler  feed 
water.  This  method  is  objectionable  because,  with  a 
ra])idl\-  fluctuating  load  such  as  is  encountered  in  rail- 
wa\-  operation,  it  would  be  impossible  for  the  operators 
to  change  from  electric  to  steam  fast  enough  to  follow 
the  load  fluctuations  and  the  irregularities  of  boiler 
feeding;-. 


234 


THE    ELECTRIC  JOCRWIL 


Vol.   XVIII,   Xo. 


F/oTf  To/rfi-— Bleeding  steam  from  the  main  tur- 
bine generating  unit  by  means  of  a  flow  valve  has  also 
been  tried  out.  However,  this  introduces  a  complica- 
tion in  the  operation  of  the  main  turbine  units.  There 
is  alwa\s  a  dispute  in  regard  to  the  water  rate  of  the 
unit.     There  is  danger  of  the  flow  valve  sticking  and 


mi 

r-^-^^ 

H  \ 

y^M\ 

vm.  '^ 

h    4 

§, 

FIG     I  — HORIZONT.XL  REGl'L/XTOR  WITH   STRING  .\ND  BEI.L  CR.\NK 
MECH.\NISM 

Mounted  on  house  turbine. 
Steam  being  taken  at  light  loads  from  the  heater  hack 
into  the  turbine,  thus  causing  overspeed. 

Combinations — Some  plants  make  use  of  all  steam 
driven  auxiliaries  and  then  depend  on  a  by-pass  valve, 
01  some  form  of  flow  valve  to  by-pass  such  amount  of 
steam  as  is  not  required  in  the  feed  water  heater,  back 
into  the  main  turbine  unit  at  one  of  its  low  pressure 
stages.  This  results  in  a  rather  complicated  piping  sys- 
tem, introducing  a  considerable  quantity  of  air  which 
puts  additional  burdens  on  the  air  puni])  and  condenser. 
This  system  also  requires  hand  operation,  with  result- 
ant objections. 

The  House  or  AuxiUary  Turbine  .\  house  or  aux- 
iliarx  turbine  is  used  in  generating  stations  in  which  all 
of  the  auxiliaries,  except  the  boiler  feed  pum]>,  are  elec- 
trically driven.  In  one  system  a  condensing  turbine  is 
used,  exhausting  into  a  barometric  condenser  through 
v/hich  the  condensate  from  the  main  generating  unit 
passes.  The  heat  from  the  exhaust  steam  of  the  tur- 
bine is  absorbed  by  the  condensate.  This  system  does 
not  answer  the  requirefnents  of  maintaining  a  constant 
feed  water  temperature  at  all  times,  unless  some  method 
is  provided  to  vary  the  load  on  the  auxiliary  turbine. 
The  amount  of  load  taken  by  the  auxiliary  turbine  will 
vary  according  to  the  quantity  of  water  to  be  heated, 
both  condensate  and  make-up.  Some  auxiliary  de- 
vice, therefore,  is  necessary  to  vary  the  load  on  the  tur- 
bine. .\n  added  complication  of  this  scheme  is  the  pip- 
ing, which  must  be  so  arranged  as  to  allow  the  supply 
of  make-up  water  to  be  delivered  into  the  condensate 
line  between  the  condensate  pump  of  the  main  turbine 
unit  and  the  bnrcmietric  condenser. 

The  other  system  of  auxiliary  turbine  proposed  and 
placed  in  actual  operating  service,  is  the  non-condensing 
turbine,  exhausting  into  an  open  feed  water  heater.  In 
this  system  all  of  the  auxiliaries,  excepting  the  boiler 
feed  pump,  are  electrically  driven.     The  auxiliary  tur- 


bine is  electrically  connected  to  the  main  generating  bus 
of  the  station  through  a  bank  of  step-up  transformers. 
In  order  to  take  care  of  the  variation  of  steam  demands 
on  the  auxiliary  turbine,  the  load  on  this  turbine  is 
varied  by  means  of  an  automatic  controller. 

To  the  piston  of  this  automatic  controller  i^  cn:)- 
nected  one  end  of  a  flat  spring,  the  other  end  beinu  :.! 
tached  to  the  bell  crank  operating  the  admission  \al\c 
to  the  turbine,  as  shown  in  Fig.  i.  The  piston  i- 
actuated  by  water  pressure  supplied  from  the  house  sys- 
tem. The  pressure  for  actuating  the  diaphragm  of  the 
controller  is  taken  from  the  main  auxiliary  exhaust 
header  at  a  point  about  20  feet  from  the  turbine,  so 
that  this  pressure  remains  practically  constant  under 
balanced  conditions  and  is  not  influenced  by  a  sudden 
change  in  load  of  the  auxiliar\'  turbine. 

To  illustrate  the  operation  of  this  controller, 
a-sunie  the  following  conditions: — Load  on  main  gen- 
erating units  4000  kw ;  water  being  supplied  to  heaters 
by  condensate  pumps  at  the  rate  of  Soocxd  pounds  per 
hour;  load  on  auxiliary  turbine  to  supply  the  necessary 
steam  to  raise  the  temperature  of  the  feed  water  from 
50  to  215  degrees,  150  kw ;  pressure  on  auxiliarj'  header, 
one  pound  gage.  Now  assume  that,  due  to  a  sudden 
change  of  load  to  6000  kw  on  the  main  units,  such  as 
constantly  occurs  in  central  stations  supplying  either 
an  exclusive  railway  load,  or  a  combination  lighting  and 
railway  load,  the  amount  of  condensate  to  the  feed 
water  heaters  is  increased  from  80000  to  no  000 
pounds  per  hour.  In  order  to  ''laintain  the  temperature 
of  the  feed  water  constant,  or  nearly  so,  it  will  be  neces- 
sary to  increase  the  quantity  of  exhaust  steam  from  the 
iuixiliary  turbine  in  approximately  the  same  ratio  or 
about  40  percent. 

The  auxiliaries  of  the  station  will  recjuire  prac- 
tically no  additional  power  under  the  increased  load 
conditions.  It  is  evident  that,  if  sufficient  steam  is  to 
be  furnished  from  the  auxiliary  turbine  to  heat  the  in- 
creased amount  of  condensate  to  a  maximum  tempera- 
ture, the  load  on  the  auxiliary  turbine  must  be  corre- 

Operating  Cylinder 


To  Exhaust  Main 
IIG.   2— .\1.\SI).\    HORIZOXT.VL  TYPE   HOUSE  TURBINE  CONTROLLER 

sf^ndingly  increased.     This  is  accomplished  in  the  fol- 
Irwing  manner: — 

When  the  quantity  of  condensate  is  increased  from 
So  000  to  no  000  pounds  per  hour,  the  result  is  a  slight 
reduction  in  pressure  on  the  auxiliar\^  header.     This  is 


A]  ay,   1921 


THE   ELECTRIC  JOURNAL 


^35 


because  the  auxiliary  turbine  is  not  supplying  sufficient 
steam  to  maintain  one  pound  pressure  on  the  diaphragm 
of  the  controller,  which  will  therefore  move.  This 
movement  operates  the  pilot  valve,  admitting  water  to 
the  cylinder  of  the  controller.  The  tension  on  the  aux- 
iliary spring  between  the  controller  and  the  bell  crank 
actuating  the  admission  vahe  to  the  turbine  is  increased, 
increasing  tlie  steam  flow  into  the  turbine.  The  addi- 
tional load  is  built  up  through  the  liank  of  steii-up  trans- 
formers between  the  auxiliary  Inis  and  the  main  bus. 
Under  these  conditions,  that  is  with  a  load  of  6000  kw, 
the  auxiliary  turbine  is  now  delivering  150  kw  ti)  the 
auxiliaries  and  approximately  75  kw  lo  the  main  bus. 
'['his  condition  of  balance  both  in  electrical  load  and 
steam  supply  for  heating  the  feed  water  remains  con- 
'^tant  initil  another  change  takes  place  in  llie  Ih.-kI. 

PROTECTUE  FEATURES 

Because  the  house  generator  runs  in  [>arallel   with 


the  main  station  bus,  it  is  imperative  that  adetpiate 


FIG-   3 — SCHliM.MIC   D1..\GR.'\M    OF  AUTOMATIC    PROTECTION    FOR 
AUXILIARY  TURRINE 

tective  devices  be  provided  so  that  in  case  of  any  ab- 
normal disturbances,  the  auxiliary  turbine  mav  be 
promptly  cut  off  from  the  main  generating  bus,  thereby 
permitting  a  continuous  and  uninterrupted  operation  of 
the  auxiliaries.      This  is  accomplished  .is   follows:-- 

/ — In  case  of  rise  in  fre(|uency  (ju  Ihc  main  gen- 
erating bus,  it  is  essential  that  the  auxili.iry  (urbine  trip 
I  ut  the  bus  tie  switch  before  the  over-speed  device  on 
the  auxiliary  turliine  may  operate.  This  form  of  pro- 
tection is  secured  by  an  overspeed  switch  on  the  shaft 
of  the  auxiliary  turbine  opening  the  main  tie-switch  be- 
tween the  transfinniers  rmd  niain  generatiiii;  bus. 

2 —  1  o  |ire\ent  tnnible  from  a  reduction  in  the  main 
.generating  Inis  frequency,  due  to  either  overload  or 
high-tension  dislurbances  on  main  bus.  an  under-speed 
switch  is  also  incorjiorated.  This  device  is  mounted  on 
the  end  of  the  turbine  slnaft  so  that  in  case  of  a  fre- 
(luency  lower  than  normal,  the  bus  tie  switch  will  oper- 
ate. Were  it  not  installed,  the  lowering  of  freipiency 
and  consequent  drop  in  voltage  would  cause  the  auxil- 
iaries of  the  station  to  drop  out,  as  these  are  all  elec- 
trically operated  and  equipped   with   contactor  c.introl. 

If  the  station  bus  voltage  is  maintained  by  a  Tirrill 
regulator,  the  frequency  could  become  very  low  before 
the  contacts  of  the  control  equipment  would  open.     A 


further  object  of  the  underspeed  switch  is  to  prevent 
the  slowing  down  of  the  auxiliaries,  including  the  motor 
driven  exciter,  in  case  of  a  reduction  in  the  frequency 
of  the  main  bus.  This  also  prevents  the  lowering  of  the 
fiequency  of  the  auxiliary  turbine,  preventing  the  drop- 
pnig  out  of  the  contactors  under  this  condition.  The 
idea  of  the  under-speed  device  is  to  keep  the  auxiliaries, 
including  the  motor  driven  exciter,  up  to  speed  at  all 

I'ABLI.    ; — MONTHhV    STATION     I'KliFORlI ANCE    FOR  FEBRUARY, 
lilil 

Feed    Water    temperature — leaving    henter 214'  F. 

Feed    Water    temperatvire — goinjr    to    heater 54*  F. 

Peed    Water    weight     45928  000  lbs. 

Total    Kw-hr.    main    units 2  063  220 

Kw-hr.    generated    by    auxiliary    turbine     '. 124  300 

tCw-hr.    delivered    to    main    bus    25   100 

Kw-hr.    taken   from   main    bu.s 

Kw-hr.    total    to    auxiliaries 99  200 

Evaporation    per    lb.    fuel     6.08 

B.t.u.   per   lb.    of   coal    as   fired 8645 

Puel    per    Kw  hr. — total    station     3.62 

times  and  to  enable  the  auxiliaries  to  be  kept  at  a  normal 
speed,  in  case  of  low  steam  pressure  when  it  is  desiral)Ie 
ti'  hang  on  to  the  load. 

_i — Low  voltage  on  the  main  generating  bus  is  taken 
^  care  of  by  potential  rela\s.  These  will  close  their  con- 
tacts in  case  of  low  |)oteiitial,  thereby  energizing  the  trip 
C(jil  of  the  bus  tie  switch,  cutting  the  auxiliary  turbine 
free  from  the  main  generating  bus.  If  this  condition 
Vvas  not  taken  care  of  the  auxiliaries  would  drop  out. 

4 — Should  the  auxiliary  turbine  be  shut  down  for 
repairs  or  overhauling,  power  for  the  auxiliaries  is 
taken  from  the  main  generating  bus.  In  this  case  inter- 
locks are  provided  on  the  disconnecting  switches  and  oil 
switches  to  prevent  the  operation  of  the  main  bus  tie 
switch.  Interlocks  are  also  provided  on  the  disconnect- 
ing switches  to  permit  the  station  operator  to  test  out 
the  oil  switch  with  the  disconnecting  switch  open,  be- 
fore synchronizing  the  .uixiliary  turbine  with  the  bus. 

5 — High  current  protection  is  taken  care  of  bv  in- 
duction type  relays  set   for  approximately  300  percent 

TABLE    II — ANALYSIS    OF    A    CENTRAL    STATION    SUPPLYINO    A 
RAILWAY    AND    LIGHTING    LOAD    AND    A    CENTRAL    .STEAM 
HEATING   SYSTEM 

1 — Water  .evaporated   in  twelve  months.  .  .1  070  5:iO  558  lbs. 

2 — Average   temperature   feed    water 180°   F. 

3 — Average   temperature    initial 60^    F. 

4 — Rise  in  heater   115°    F. 

'' — Total  steam  in  pounds  to  auxiliaries..  111500  000 

fi — B.t.u.  per  ])ound  of  steam  at  zero  gauge  970 

7 — Water    rate    auxiliary    turbine 35  lbs.  pr.  Kw-hr. 

.-< — Size  of  auxiliary  turbine    1200  k.w. 

n — Water     rate     per     B.Hp-hr.     at     motor 

.shaft     30.2  lbs. 

Ill — Total    lbs.    steam    motor    driven    auxili- 

[iries,    tlircuish    auxiliary   turbine....  li]  000  000 
U— SavinL'    per    year     in     lbs.     steam    over 

pres.ent    mi.\ed    drive    (5)  —  (10)....  50  SOO  000 

12 — Evaporation  per  lb.  of  coal  (.SSOOB.t.u.)  6 

i:i — (11)    divided    by    (12)           8  400  000  lbs,  *  4  3  00  tons 
14 — Tons    of    coal    saved    per    year    due    to 
increasing     average     temjjerature     of 

feed   water  from   175  to  215  degrees  1417 

15 — Average    cost    per    ton    1920 $6.25 

16 — Total    cost     (13)    and     (14)     $35  721.25 

17 — Saving  in   dollars  per  year  in   coal.  .  .  .  35  lOfi.35 
18 — Estimated   saving  per  year  in   mainten- 
ance   of    electrically    driven    auxiliar- 
ies  over   steam ,  6  900.00 

19 — Total    annual    saving    $42  006.35 

normal  current  and  fi\e  seconds  delay.  These  relax's 
are  practically  inoperative,  except  in  case  of  short-cir- 
cuits on  the  auxiliary  bus. 

An  interesting  applicition  of  this  form  of  house 
turbine  has  already  been  made  at  the  plant  of  the  Des 

*Increasing    feed    water    temperature    to    215    degrees    F.    will    give 
945  000    kw.-hr.    from    the    auxiliary   turbine,    also    for    each    10    degrees 
rise    in    feed    water    temperature    one    percent    saving    of    fuel    or    four 
dollars. 


220 

Momes  City  Railway  Co.upany  at  Des  Momes,  Iowa 
and  has  been  in  very  successful  operation  for  a  period 
of     year.         The     regulator     acts     through     a     levei 
mechanism    on    the    auxiliary    spring    of    the    turbine 
governor.     In  order  to  secure  successful  operation  ot 
tiie  hydraulic  control,  considerable  care  had  to  be  taken 
ia  the  piping  to  and  from  the  exhaust  main.     1  he  upper 
p.pe,  shown  in  Fig.  2,  merely  serves  to  conduct  pressure 
fioni  the  exhaust  header  to  a  reservoir  and  the  conden- 
sation   which   takes   place   in   the   reservoir   is    carried 
back  into  the  exhaust  header  by  the  lower,  or  drain  pipe. 
It  was  found  from  actual  experience  that  it  was  im- 
possible  to   secure    satisfactory   operation    with   only  a 
single  pipe  leading  to  the  diaphragm  of  the  regulator 
nithout  the  use  of  the  reservoir. 

The   economics   of    the   auxiliary   turhine   are   ex- 
iremelv  interesting  as  shown  in  Table  I. 

The  charts  from  the  recording  instruments  ot  the 
De>  Mines  City  Railway  station  shown  in  Figs.  4  and 


THE   ELECTRIC  JOURX.IL 


Vol.  XVHI,  Xo.  5 


212  degrees.     An  analysis  of  the  saving  expected  from 
the  auxiliary  turbine  is  given  in  Table  II. 

The  advantages  and  disadvantages  of  the  auxiliary 
turbine  may  be  summed  up  as  follows: — 

ADVANTAGES  Of   AlXIl.lARY   TURBINE  DRIVE 

1— Maximum  feed  water  temperature  during  pe:,k  loads 
when  greatest  boiler  capacity  is  needed,  thereby  ptrmitling 
use  of  less  boiler  capacity  on  peak  load. 

7— Considerable  reduction  in  auxiliary  piping  which  i^ 
required  when  each  auxiliary  is  steam  driven  requiring  bulb 
steam  and  exhaust  piping,  also  oil  piping. 

3— Reduction  in  condensalion  losses  due  to  eliminating 
anxiliarv  exhaust  and  steam  piping,  the  h^.scs  ot  which  go 
„n  ior  8700  hrs.  per  year  as  it  is  not  practicable  to  shut  oft 
valves  on  main  auxiliary  header  each  time  a  mam  unit  is 
shut  down. 

1— (ireatcr  reliability  secured  in  using  ii.duclion  motors 
of  very  rugged  design  as  compared  to  small,  inerficient,  high 
speed  turbines,  necessitating  gearing  in  some  cases  to  secure 
best  speed  for  pumps. 

S— Lower  steam  consumption  for  auxiliaries  account  of 
higher  efliciency  of  motors  and  large  anxihaiy  turbine. 


FIG-  4— VOLUME  KECORD  OF  CONDF.NS.ATE 

S  illustrate  the  actual  operation  of  this  system.     These 
two  charts  clearlv  show  that  the  application  of  the  aux- 
iliarv  turbine,  with  control  .levices  as  mentioned,  is  not 
onlv  correct  in  theorv,  but  in  actual  practice.     It  will  do 
exactlv  what  it  was  designed  to  do,  and  in  addition  to 
maintaining  a  constant  feed  water  temperature,  regard- 
less of  the  load,  it  has  carried  the  auxiliaries  ot   the 
station  and  has  delivered  some  power  to  the  mam  bus. 
\nother  application  of  the  house,  or  auxiliary  tur- 
bine   has   been   proposed    for   a   large   central    station, 
which  not  onlv  supplies  a  railway  and  lighting  load,  but 
also  is  burdened  with  a  large  heating  system.     In  this 
case  not  only  the  water  for  boiler  purposes,  hut  m  addi- 
tion a  large  amount  of  itiakeup  water  must  be  heated 
on  account  of  the  enormous  quantity  of  steam  sent  out 
through  the  heating  mains,  which  requires  that  make-up 
v^ater  be  taken  from  an  outside  source  and  heated  to 


FIG.    5 


-TEMPERATURES    OF    CONDENSATE    AND    FEEL    NVMKK 


f^Lower  maintenance  cost  on  large  a."''"'';;'>„^'.":;;';:,'i 
and  ^tors  driving  auxiliaries,  as  compared  to  many 
turbines  or  engines  .ertain 

7_M1  water,  condensate  or  raw,  v^""'?'"^.  ?„,  '  i  ni- 
.„ofint-^of  air  and  »"•«^--'^-r  ^.XTa't  "id^-ble 
nating  air  before  water  is  fed  into  h"^^'^,  ?;  •*;,,  „i,^ 
amount  is  earned  in  with  feed  ^^^^  "' '"," VVoding  ihc  m.  Air 
corrosion,  and  with  steel  <^""°T  of  air  is  carrie^l  over  with 
is  driven  ofT  and  a  lesser  n"^"*  *>  ^^ ,^'^^^  ,,^f,,,  ,,,  ,;,  p„mp. 
steam  and  reduction  of  amount  of  air  nan 
DISADVANTAOI'.S 

.-Initial  cost  is  somewhat  higher  than  that  of 
sleam  or  combination  driven  auxiliaries. 

I-^Factor  of  safetv  in  a  station  of  four  main  gen- 
erating units  each  equipped  with  steam  driven  auxil- 
iaries, is  higher  than  in  the  same  station  equipped  with 
one  auxiliary-  turbine. 

BIBI.IOCRAI'IIY 

XT   F   L    \   Prime  Movers  Committee  •f)20 '^''P"''' J^'\?;";Xui': 
S' lower  Plants,  Fernald  and  Orrock  Ban  Grosser  Elekt.iz...... 

Werke.  Klingenbcrg. 


rsi 


The  Electric  Journal 


VOL.   XVIII 


JUNE.    1921 


NO.  6 


The    completion    of    the    preHminary 
Electrical  trials    of    the    U.    S.    S.    Tennessee 

Propulsion         marks    an   epoch   in    naval    history. 
for  While  not  the  first  capital  ship  to  be 

Battleships  electrically  driven,  it  is  the  first  one, 
designed  especially  for  electric  pro- 
pulsion, in  which  the  full  advantage  of  this  system  has 
been  utilized.  The  success  of  the  U.  S.  S.  New  Mexico 
was  sufficient  demonstration  of  the  possibilities  of  elec- 
tric drive.  From  a  military  standpoint,  however,  she 
was  not  much  in  advance  of  her  sister  ships,  as  she  was 
originally  designed  for  direct  turbine  drive  and  the  elec- 
tric propelling  machinery  was  fitted  into  the  space 
available  with  as  little  change  as  possible. 

At  the  time  it  was  decided  to  install  electric  propell- 
ing machinery  in  capital  ships,  it  was  realized  that  a 
more  advantageous  disposition  of  the  machinery  could 
be  made,  but  as  the  designs  of  the  U.  S.  S.  New  Mexico 
v/ere  so  far  advanced,  it  was  decided  not  to  make  any 
radical  changes.  When  the  designs  of  the  U.  S.  S. 
Tennessee  were  made,  however,  full  advantage  was 
t.iken  of  the  possibilities  which  the  electrical  system 
offered,  to  obtain  a  layout  giving  the  maximum  protec- 
tion to  the  machinery  which  this  system  allows.  The 
experience  that  had  been  gained  from  the  war,  up  to 
that  time,  showed  the  vital  necessity  of  adequate  under- 
water protection  if  the  ships  were  to  be  capable  of  re- 
maining in  action  during  a  modern  battle  where  tor- 
pedoes are  used  so  freely.  The  freedom  with  which 
the  naval  designer  can  dispose  of  his  machinery  with 
the  electrical  system,  makes  possible  bulkhead  sub- 
divisions not  feasible  with  any  other  type  of  propelling 
machinery,  the  location  of  which  is  necessarily  governed 
by  the  position  of  the  propeller  shafts,  so  that  the 
U.  S.  S.  Tennessee  is  probably  the  best  protected  capital 
ship  afloat  today. 

As  has  been  the  histoiy  of  electrical  development 
in  many  branches  of  industry,  the  real  advantages  have 
not  always  been  obvious  or  fully  appreciated.  Generally 
in  such  a  new  development,  stress  is  laid  upon  such  fac- 
tors as  economy  and  it  usually  does  not  develop,  until  a 
very  careful  study  and  detail  design  has  been  made,  that 
there  are  other  advantages  of  even  greater  importance. 
In  the  design  of  battle  ships,  any  tool  that  will  enable  a 
better  fighting  machine  to  be  built,  can  be  used  to  ad- 
vantage if  it  does  not  have  other  characteristics  which 
would  distract  from  the  operation  of  the  machine  as  a 
whole.  While  in  the  first  place,  stress  was  laid  upon 
the  economy  of  electric  drive  and  while  the  claims  of 
the  advocates  of  electric  drives  have  been  justified  by 


the  operation  of  the  U.  S.  S.  New  Mexko,  it  is  believed 
that  the  greatest  advantage  of  the  electric  system  is  the 
fact  that  it  enables  the  naval  constructor  to  build  a 
better  fighting  machine  for  modern  warfare. 

The  idea  in  using  electrical  machinery  for  propell- 
ing ships,  is  not  of  recent  origin.  As  far  back  as  thirty 
)'ears  ago,  the  idea  was  suggested  to  the  Navy  Depart- 
ment to  drive  ships  then  contemplated  with  electrical 
machiner}'  along  almost  the  same  lines  as  were 
eventually  adopted.  If  the  suggestion  had  been  carried 
out  at  that  time,  it  would  probably  have  been  a  failure, 
as  the  development  of  suitable  prime  movers  and  elec- 
trical machinery  had  not  progressed  far  enough  to  en- 
able results  to  be  obtained  comparable  with  what  was 
then  possible  with  the  existing  systems.  During  this 
period,  however,  the  steam  turbine  and  the  electric  gen- 
erator have  been  highly  developed  for  central  station 
use  in  capacities  much  greater  than  required  for  our 
modern  ships  so  that,  except  in  so  far  as  slight  modifi- 
cations were  required  for  fitting  the  machinery  into  a 
ship,  no  new  problems  were  involved.  This  was  also 
the  case  with  the  motors  used  for  driving  the  propellers. 
Larger  machines  have  been  developed  and  in  use  for  a 
number  of  years  under  severe  operating  conditions  in 
our  steel  mills,  so  that  the  problem  was  reduced  to  the 
comparatively  simple  one  of  a  study  of  the  conditions 
under  which  a  machine  had  to  operate  and  then  of  de- 
signing it  with  the  proper  characteristics.  While  in  the 
m.ain,  this  was  a  simple  problem,  it  involved  an  immense 
amount  of  detail  study  as  is  evidenced  by  the  descrip- 
tions of  the  various  parts  of  the  equipment  given  in  this 
issue  of  the  Journal. 

With  the  adoption  of  electric  propelling  machinery, 
the  American  naval  constructor  has  been  enabled  to 
design  a  capital  ship  with  such  protection  that  it  is  diffi- 
cult to  conceive  of  such  a  ship  being  seriously  incon- 
venienced by  under  water  attack.  The  progress  in  the 
development  of  armor  protection  has  been  such  that  a 
modern  ship  can  stand  an  immense  amount  of  battering 
without  being  put  out  of  action,  as  was  instanced  by  the 
"Warspite"  in  the  battle  of  Jutland  where,  owing  to  a 
defect  of  the  steering  gear,  she  was  compelled  to  circle 
around  for  a  considerable  period  and  received  at  one 
time  or  another,  the  fire  of  practically  the  whole  Ger- 
man fleet  but  still  remained  an  active  fighting  machine. 
The  experiences  of  war  forced  the  British  to  adopt  some 
means  of  protection  against  torpedo  attack  with  the  re- 
sult that  they  fitted  a  great  many  of  their  ships  with  the 
so-called  "bulge"  which  was  partially  effective.  In  the 
design  of  the  U.  .S.  S.  Tennessee,  however,  it  has  been 


238 


THE  ELECTRIC  JOURNAL 


Vol.  XVII r,  No.  6 


possible  to  incorporate  the  desired  protection  much 
more  effectively  in  the  hull  of  the  ship,  due  to  the  free- 
dom with  which  the  machinery  could  be  disposed,  so 
that  .a  commander  of  a  fleet  of  such  vessels  could  go 
into  action  with  the  feeling  that  he  was  practically  im- 
mune from  torpedo  attack  and  could  maneuver  accord- 
ingly instead  of  being  restrained,  as  were  the  British 
during  the  battle  of  Jutland,  by  the  repeated  efforts  of 
the  enemy  to  seriously  cripple  the  principal  fighting 
units  by  using  large  numbers  of  torpedoes. 

Wilfred  Sykes 


In  considering  any  new  engineering 
The  Battleship  development  or  undertaking,  it  is  of 
is  a  the  greatest  importance  to  get  clear- 

Fighting  Ship  ly  in  mind  the  fundamental  reasons 
for  such  development,  and  the  fun- 
damental results  to  be  accomplished.  It  is  equally  im- 
portant to  keep  these  ideas  in  mind  continually  during 
the  period  of  consideration  and  development. 

Fundamentals  are  a  guide  to  our  mind;  they  keep 
us.  on  the  track  and  prevent  secondary  consideration.-; 
from  assuming  undue  proportions.  Most  engineering 
mistakes  are  due  to  lack  of  appreciation  of  the  basic 
laws  governing  our  own  progress.  Fundamentals  pro- 
tect us  from  the  results  of  prejudice  and  limited  ex- 
perience; they  enable  us  to  go  safely  into  the  future 
and  to  decide  new  questions  correctly  in  the  light  of 
our  past  experience. 

For  a  number  of  years  there  has  been  a  good  deal 
of  discussion  about  electrically-driven  battleships. 
Looking  back  at  these  discussions,  it  is  quite  apparent 
that  many  of  them  were  affected  by  prejudices  and 
the  pride  of  attainment.  Many  of  the  men  taking 
part  in  the  discussions  did  not  keep  in  mind  the  funda- 
mental fact  that  a  battleship  is  a  fighting  ship.  In 
considering  the  question  of  the  battleship,  nothing 
should  govern  but  fighting  qualities, — difficulties  of 
accomplishment,  cost,  appearance,  convenience,  effi- 
ciency, cost  of  operation,  are  all  of  secondary  consid- 
eration, and  should  be  sacrificed  willingly  and  com- 
pletely, if  by  so  doing  the  fighting  quality  Is  enhanced. 

About  a  year  ago  the  writer  had  occasion  to 
discuss  the  subject  of  electrically-driven  battleships 
with  a  number  of  English  engineers  who  had  had  much 
to  do  with  the  designing  of  propelling  machinery  for 
battleships.  The  distinct  impression  was  received  that 
their  minds  were  not  open;  that  their  decisions  and 
judgments  were  vitiated  by  the  results  of  their  own 
past  decisions.  They  had  not  clearly  in  mind  that  what 
had  already  been  done  was  of  no  particular  value ; 
that  the  thing  to  keep  constantly  in  mind  was  that 
"the    battleship    is    a    fighting    ship."     They    were    all 


favoring  turbine  gear  drive.  There  is  no  question  that 
the  turbine  gear  drive  was  a  great  advance  over 
the  old  reciprocating  engine,  judged  by  the  greater 
fighting  ability  of  the  ship.  There  seemed,  however, 
to  be  an  unwillingness  to  consider  the  electric  drive 
from  the  same  standpoint. 

Now,  in  what  way  does  the  propelling  system  of 
a  battleship  affect  its  fighting  qualities?  Briefly,  they 
may  be  stated  as  follows: — 

Reliability 

Economy' 

Weight 

Space  occupied 

Flcxibilitv  of  arrangement 

Flexibility  of  operation  and  maneuvering 

Possibility  of  protection  from  shell  or  torpedo  explosion 

Quickness  and  ease  of  making  repairs  either  on  board  or  in 
dock 

Possibility  of  a  shutdown  of  the  propelling  machinery 

The  effect  of  the  propelling  machinery  on  the  design  of  the 
ship  itself. 

The  effect  of  the  propelling  machinery  upon  the  arrangement 
and  design  of  other  apparatus. 

Each  of  these  has  an  effect  upon  the  fighting 
quality  of  the  ship,  either  directly  or  secondarily, 
through  its  effect  upon  other  matters. 

It  is  quite  evident  to  an  unprejudiced  observer 
that  the  electrical  propelling  machinery,  as  installed 
in  the  new  battleship  Tennessee,  excels  in  all  of  the 
above  qualities,  with  the  possible  exception  of  those  of 
weight  and  space,  direct  comparisons  of  which  are  not 
available.  Also  there  is  no  direct  comparison  availa- 
ble in  regard  to  the  economy.  However,  analysis  of 
this  item  shows  that  over  the  entire  range  of  speed  and 
power,  the  electric  drive  should  be  the  most  economical. 

In  having  the  open-mindedness  which  led  to  con- 
viction, the  courage  to  follow  conviction,  and  the  skill 
and  engineering  ability  to  carry  out  plans,  our  Navy 
Department  and  the  contractors  working  under  their 
supervision  have  produced  a  ship  of  which  we  can  all 
be  proud.  More  than  that,  they  have  won  a  battle, 
not  of  shells  but  of  engineering.  The  time  is  near 
when  electric  propulsion  will  be  recognized  by  all  as 
not  only  successful,  but  as  excelling,  and  that  the  Ten- 
nessee is  the  prototype  of  the  future  battleship. 

Since  the  text  for  this  issue  was  prepared,  the 
Tennessee  has  completed  her  official  trials.  It  will  be 
a  great  satisfaction  to  everj'one  who  has  been  con- 
nected with  this  important  development  to  know  that 
the  propulsion  system  met  all  of  its  guarantees  and 
showed  gratifying  results  as  regards  steam  consump- 
tion, which  in  every  test  were  materially  better  than 
guarantees.  Full  details  of  the  trials  will  be  published 
later.  These  results  are  further  proof  of  the  wisdom 
and  foresight  of  the  Navy  Department  in  selecting 
electric  drive  for  their  capital  ships. 

W.  S.  RUGG 


EIocHi'lc  T)r]vo  and  2'ho  U,  >S,  5>  Tdj1ivo5^o3 


II.  M.  SOUTIIGATE 

Manager,  Washington,  D.  C.  Office, 
Westinghouse  Electric  &  Mfg.  Company 


ONE  of  the  very  important  advantages  of  a  modem 
navy — and  one  that  is  being  emphasized  too 
little  in  the  current  naval  discussion — is  that  it 
acts  as  an  immense  laboratory  for  experiments  in 
marine  engineering.  Everyone  will  admit  that 
America's  merchant  marine  should  be  progressive  and 
should  adopt  new  and  better  forms  of  equipment  as 
soon  as  they  are  thoroughly  developed,  but  few  realize 
the  difficulties  involved  in  transferring  an  application 
successful  on  land  and  adapting  it  for  marine  use.  So 
great  are  these  difficulties,  so  large  is  the  expense, 
even  in  case  of  success,  and  so  huge  the  loss  in  money 
and  prestige  in  case  of  failure,  that  few  private  marine 
interests  can  afford  to  be  the  first  to  introduce  impor- 
tant   radical    departures     from     ordinary    procedure. 


American  steel  industry,  and  though  the  ships  never 
fired  a  shot  against  an  avowed  enemy  of  the  United 
States,  and  were  therefore  in  one  sense  a  total  loss  to 
the  nation,  their  cost  was  an  insignificant  price  to  pay 
for  the  wealth  that  they  created. 

Similarly  (to  mention  only  that  class  of  apparatus 
which  is  most  familiar  to  the  writer)  the  Navy  has  been 
responsible  for  the  development  of  all  of  the  modem 
drives  for  ships.  British  destroyers  were  the  first  to 
use  the  direct-connected  turbine ;  an  American  collier 
proved  the  practicability  of  the  geared  turbine,  which 
is  now  one  of  the  dominant  types  of  ship  propelling  ma- 
chinery; German  submarines  developed  the  marine 
Diesel  engine,  which  is  the  most  economical  of  all 
drives;  and  the  American   Navy  has  boldly  departed 


I'lU.   I — OFFICERS  OF  THE  TENNESSEE  WHEN  COMMISSIONED  AT  THE  BROOKLYN   N.WY  Y.^RD* 


Hence  it  is  a  fact  that  the  Navy,  which  is  always  in- 
terested in  new  developments,  has  been  the  medium 
through  which  a  large  number  of  the  modern  improve- 
ments have  been  introduced  into  the  merchant  marine. 
Undoubtedly  the  foremost  example  of  the  influ- 
ence exercised  by  the  Navy  in  American  industry  is  our 
steel  industry.  In  the  early  eighties  of  the  last  century, 
America's  fleet  of  fighting  vessels  consisted  of  a  few 
obsolete  monitors.  The  need  for  a  real  Navy  was  ap- 
parent, however,  and  plans  were  prepared  for  a 
squadron  of  first  class  ships.  But  these  ships  could  not 
be  built  without  foreign  aid  because  nowhere  in 
America  could  the  forgings  needed  for  the  armor-plate 
and  the  heavy  guns  be  obtained.  To  the  everlasting 
credit  of  the  Navy,  it  refused  to  purchase  this  material 
abroad  and  made  arrangements  with  American  manu- 
facturers to  install  the  necessary  equipment  for  the  pro- 
duction of  this  armament.  Thus  the  famous  "White 
Squadron"  greatly  accelerated  the  development  of  the 


from  all  precedent  and  created  the  steam-electric 
drive,  which  is  undoubtedly  ideal  for  all  large,  high- 
powered,  variable-speed  ships  and  which,  in  the  modi- 
fied form  of  the  Diesel-electric  drive,  promises  to  share 
with  the  geared-turbine  in  the  propulsion  of  the  mer- 
chant marine. 

Though  many  engineers  undoubtedly  conceived  in- 
dependently the  idea  of  the  electric  drive  for  ships,  the 
credit  for  its  first  adoption  by  the  U.  S.  Navy  belongs 
to  Mr.  W.  L.  R.  Emmett,  consulting  engineer  of  the 
General  Electric  Company,  actively  supported  by  Cap- 
tain R.  S.  Griffin,  Captain  C.  W.  Dyson,  and  Admiral 
H.  I.  Cone,  all  of  the  Bureau  of  Steam  Engineering, 
U.  S.  Navy. 

Although  vessels  had  been  electrically  propelled  as 
early  as  1893,  the  first  installation  of  importance  was 
the  collier  Jupiter,  commissioned  in  1913.  The  Jupiter 
was  one  of  three  sister  ships — one   (Jupiter)   electric- 

*Copyright   by   Underwood    &   Underwood,    N.   Y. 


240 


THE  ELECTRIC  JOURNAL 


Vol.  X^aII,  No.  6 


ally  propelled;  another  {Neptune)  equipped  with 
geared  turbines;  and  the  third  (Cyclops),  whose  disap- 
pearance is  one  of  the  tragic  mysteries  of  the  war,  with 
reciprocating  engines.  This  was  truly  an  experiment 
on  a  large  scale  and  demonstrated  the  reliability  of  elec- 
tric propulsion  and  its  desirability  for  use  in  capital 
ships,  and  the  excellence  of  the  geared-turbine  drive 
for  all  other  classes. 

The  next  step  in  the  history  of  electric  drive  was  its 
installation  on  a  battleship  in  1915.  Three  ships  were 
authorized  at  that  time,  New  Mexico,  Mississippi,  and 
Idaho,  the  first  to  be  built  at  the  New  York  Navy  Yard, 
and  the  other  two  at  private  yards.  The  Navy  Depart- 
ment requested  the  private  builders  to  quote  on  elec- 
tric drive  but  they  refused  to  consider  anything  so  un- 
familiar, so  the  Nav>'  decided  to  do  the  work  itself, 
which  is  another  instance  of  its  initiative.  Hence  the 
Nezv  Mexico  has  the  honor  of  being  the  first  electric 


Of  these,  the  Tennessee  has  successfully  com- 
pleted her  final  trials,  and  the  Maryland  and  Cali- 
fornia will  be  ready  for  trials  this  year.  The  Tennes- 
see is  the  latest  of  our  battleships  to  join  the  fleet.  Her 
hull  design  was  supervised  by  Rear  Admiral  D.  W. 
Taylor,  Chief  of  the  Bureau  of  Construction  and  Re- 
pair, and  her  ordnance  by  Rear  Admiral  J.  Strauss, 
Chief  of  the  Bureau  of  Ordnance.  Her  machinen,'  was 
built  under  the  supervision  of  Rear  Admiral  R.  S. 
Griffin,  Engineer-in-Chief,  U.  S.  Nav}',  Rear  Admiral 
C.  W.  Dyson  and  Commander  S.  M.  Robinson  being  in 
direct  charge  of  the  details  of  its  construction.  On 
Commander  Robinson's  appointment  as  Engineer 
Officer  of  the  Pacific  Fleet,  his  work  was  continued  by 
Commander  J.  S.  Evans.  She  was  built  in  the  New 
York  Navy  Yard  under  Rear  Admiral  G.  E.  Burd,  In- 
dustrial Manager  of  the  Yard ;  Captain  P.  B.  Dungan, 
Engineer  Officer;  and  Captain  G.  H.  Rock,  Construc- 


FIG.  2 — REAR  .\DMIRAL  D.  W.  TAYLOR* 


FIG.  3 — REAR  ADMIRAL  ROBERT  S.  GRIFFIN** 


FIG.  4 — REAR  ADMIRAL  C.   W.  DYSON' 


battleship.  She  was  commissioned  in  1918  and  her 
subsequent  performance  has  amply  justified  her  de- 
signers and  sponsors. 

Authorization  for  electrically-operated  capital 
ships  followed  rapidly  after  that,  the  present  schedule 
being  as  follows : — 

TENNESSEE  /    Practically  sister  ships  of  the  NEW 

CALIFORNIA  I     MEXICO. 

MARYLAND  j     Similar    to    the    TENNESSEE,    ex- 

COLORADO  '    cept  that  they  will  carry  eieht  16-inch 

WEST  VIRGINIA     i    guns  instead  of  twelve  14-inch  guns. 

WASHINGTON         ' 

INDIANA 

SOUTH  DAKOTA 

MONTANA 

NORTH  CAROLINA 

IOWA 

MASSACHUSETTS 

CONSTELL.\TION 

RANGER 

CONSTITUTION 

UNITED  STATES 

LEXINGTON 

SARATOGA 


These  will  be  much  larger  than  nny 
battleships  now  afloat. 


Battle  cruisers  of  immense  power  and 
speed. 


*Figs.  2  and  4  by  Clinedinst,  Wash.  D.  C. 
♦Copyright  by  Clinedinst,  Wash.,  D.   0. 


tion  Officer.  Her  contract  was  signed  in  December  28, 
1915;  her  keel  was  laid  on  May  14,  1917;  she  was 
launched  on  April  30,  1919;  and  she  completed  her 
trials  on  May  21,  1921. 

Her  trials  proved  conclusively  the  superior 
maneuvering  power  due  to  her  electric  drive.  A 
maximum  speed  of  21.378  knots  was  attained;  she 
came  to  rest  from  top  speed  in  less  than  three  minutes ; 
she  was  driven  backward  at  over  15  knots;  and  her 
turning  circle,  with  all  propellers  operating  in  one  di- 
rection and  with  rudder  hard-over,  was  less  than  700 
yards,  or  about  that  of  a  destroyer.  Her  economy 
trials  were  also  eminently  satisfactory,  and  her  steam 
consumption  guarantees  were  improved  by  from  5  to 
10  percent.  Her  trials  were  conducted  by  a  board  com- 
posed of  Rear  Admiral  G.  W.  Kline,  President  of  the 
Board  of  Inspection  and  Survey,  and  Captains  H.  D. 
Tawresey,  W.  N.  Jeflfers,  and  P.  B.  Dungan,  the  latter 
being  especially  in  charge  of  her  engineering  inspection. 

One  of  the  interesting  features  of  the  Tennessee 


June,  1921 


THE  ELECTRIC  JOURNAL 


241 


is  her  relation  to  her  name-state.  Through  a  new 
poUcy,  of  which  she  is  the  first  example,  she  has  been 
made  practically  an  extension  to  the  educational  sys- 
tem of  that  State,  since  service  on  board  of  her  provides 
an  unparallelled  course  of  training,  travel  and  educa- 


ing  as  assistant  to  the  Bureau  of  Steam  Engineering. 
Shortly  after  America  entered  the  Great  War,  he  at- 
tained the  rank  of  captain,  and  was  assigned  to  duty 
twith  Vice-Admiral  Sims  at  London.  He  had  charge 
of   all   the   submarine   chasers   in    foreign   waters,   and 


HC.  5 — COMMANDER  S.  M.  ROBINSONf 


FIG.    6 — COMMANDER   J.    S.    EVANsf 


KIG.    7 — REAR  ADMIRAL  G.   W.   KLINE 


tion,  and  native-born  Tennesseans  are  given  preference 
wherever  possible.  Prior  to  her  being  commissioned, 
Governor  Roberts  of  the  State  of  Tennessee,  and  Cap- 
tain Leigh  of  the  ship,  toured  the  State  in  the  interest 
of  recruiting,  and  as  a  result  over  half  of  her  crew  are 
native  sons. 


was  especially  concerned  with  the  installation  of  sub- 
marine detecting  devices.  For  his  work  in  this  latter 
field,  he  was  awarded  the  order  of  the  British  Empire 
by  King  George  and  the  Order  of  Leopold  by  King 
Albert.     After    the    armistice    he    was    appointed    as 


FIG.  9 — COMMANDER  CLAUDE  A.   JONES** 
FIG.  8 — CAPT.  RICHARD  H.  LEIGH* 

Captain  Richard   H.   Leigh,   Commanding   Officer  Assistant  Chief  of  the  Bureau  of  Navigation  serving 

of  the  Tennessee,  has  had  an  active  and  varied  career,  also  for  some  months  as  Acting  Chief.     Later  he  was 

His  earlier  experiences  include  a  deep-sea  survey  of  the  ordered  to  New  York  in  connection  with  the  fitting  out 

Carribean    and    North    Pacific    Seas,    service    on    the  —^r^    •  ,,.  ^    r^,-     ,■    ,   w    .,    r,   p 

,                                                                                          *  *Copyright  by   Clinedmst,   Wash.,   U.   C. 

Fnnccton  during  the  Spanish-American  War,  and  serv-  **?!''>'°  ^-^  ^"'°s  '^""T/^'h  ^^  ^■°^\-  v  ■      w    ,,    r,   p 

'                                                    '  tFigs.   5  and   6  copyright  by  Hams  &  Ewing,   Wash.,   D.  C. 


242 


THE  ELECTRIC  JOURNAL 


V'ol.  XVIII,  No.  6 


of  the  Tennessee,  assuming  command  of  this  vessel  in 
May,  1920. 

Commander  Claude  A.  Jones,  Engineer  Officer  of 
the  Tennessee,  has  devoted  himself  to  the  study  of 
marine  engineering  ever  since  his  graduation  from  the 
Naval  Academy  in  1907,  and  has  served  as  engineer 
officer  on  several  vessels.  In  1915,  when  he  was  on 
U.  S.  S.  Memphis  (the  old  Tennessee)  in  San  Domingo 
Harbor,  a  tidal  wave  struck  the  ship,  lifted  her  up- 
wards, and  then  crashed  her  down  upon  the  rocks. 
The  shock,  which  wrecked  the  vessel,  broke  the  main 
steam   pipes   and   filled   the   interior   with   live    steam. 


Jones  made  his  way  to  the  engine  room  and  helped  to 
rescue  the  crew.  He  was  very  badly  burned  and  was 
confined  to  the  hospital  for  many  months.  Upon  his 
recovery^  which  at  one  time  was  not  expected,  he  was 
assigned  to  the  Westinghouse  Company's  plant  at  East 
Pittsburgh  where  he  was  inspector  for  the  electrical 
apparatus  for  the  Tennessee.  On  its  completion,  he 
was  ordered  to  the  New  York  Navy  Yard  to  superin- 
tend the  installation  of  this  machinery,  and  was  then 
transferred  to  the  ship  as  Engineer  Officer.  The  suc- 
cessful results  of  the  trials  of  the  ship  bear  witness  to 
his  efficiency  in  organization  and  operation. 


?/tefu):ii  -"tyo  000  000  Y/orfa 

COMMANDER  R.  A.  BACHMANN    M,  C,  U.  S  N. 

U.  S.  S.  Tennessee 


FOR  a  year  the  Chief  had  worried.     For  a  year 
he  had  poured  his  soul  out  over  plans  and  blue 
prints,   and   struggled   with   yard   workmen   and 
heads  of  departments  and  the  Bureau  of  Engineering 
and  other  important  people,  for  the  Chief  had  been  or- 
dered to  the  New  York  Navy  Yard  in  connection  with 
the  building  of  the  U.  S.  S.  Tennessee  and  it  was  up  to 
him  to  see  that  generators  generated  and  the  motors 
moted  and  the  propellers  propelled ;  in  short,  that  the 
magnificient      piece 
of    electrical    engi- 
neering  which   was  ' 
designed      to      fur- 
nish    this    latest 
type    of    battleship 
with      sufficient 
h  o  r  s  e-power       t<  1 
drive    her    through 
the      water     at     a 
speed     of     twenty- 
one    knots,    should 
be  in  proper  shape 
to      deliver     the 
goods.       So      the 
Chief  had    worried 
and    now    the    day 
had   come — the   be- 
ginning     of      the 
week     of      accept- 
ance    trials    to    be 
held    over  the  offi- 
cial      course       off 
Rockland,  Maine. 

Once  before  the  writer  of  this  article  had  been  on 
a  speed  trial.  The  ship  was  one  of  our  fastest  cruisers, 
but  she  burned  coal  and  had  reciprocating  engines. 
The  excitement  had  been  intense.  The  engine  room 
was  filled  with  officers  and  enlisted  men  dripping  with 
oil,  their  faces  glistening,  their  clothes  saturated. 
It  was  impossible  to  talk.  The  thump-thump  of  the 
engines    and     pumps,     the     hiss     of     escaping    steam, 


the  rumble  of  the  shaft  filled  the  air.  Floor 
plates  glistened  with  oil,  water  and  oil  dripped  from 
frames  and  braces,  in  a  minute  you  were  soaked, 
Long,  steel  rods  shot  out  from  cylinders  like  giant  arms 
and  turned  the  crank  shafts  like  an  Italian  turning  his 
hurdy  gurdy. 

Forward  of  the  engine  room  were  the  pumps  do- 
ing their  share  of  the  work,  adding  to  the  confusing 
array    of    rods,    wheels,    cylinders,    valves,    bolts    and 

bearings  —  all  in 
r^  motion  or  assisting 
'  motion.  The  air 
pumps  —  ponder- 
ous, slow,  deliber- 
ate; the  hot  well 
pump  bringing 
each  stroke  to  a 
close  with  a  jerk, 
the  main.,  feed 
pumps,  ■  powerful, 
i  n  d  e  f  a  t  i  gable, 
short  of  stroke ; 
the  little  circulat- 
ing pumps  running 
like  sewing  ma- 
chines, joyous,  and 
light;  all  striving 
to  make  the  speed, 
helping  the  long 
steel  arms  to  shoot 
out  of  their  sleeves 
and  turn  the 
cranks  one  hundred  and  fifty  times  a  minute  or  more — 
inevitable,  powerful,  superior. 

In  the  fire  rooms  the  scene  was  no  less  active. 
Here  the  heart  of  the  ship  throbs.  Furnace  doors  fly 
open,  men  half  naked,  black  with  coal  dust,  dripping 
with  sweat  that  leaves  little  white  streaks  on  their 
skin  where  it  runs  down,  plunge  their  shovels  fierceh' 
into  tlie  heaps  of  coal  on  the  deck  and  throw  it   far 


FIG.    I — THE  TENNESSEE  MAKING  OVER  21    KNOTS  PER  HOUR  OX   HER 
TRIAL  TRIPS  OFF  ROCKLAND,  MAINE* 


'Photo  by  International  Film  Co. 


June,  192 1 


THE  ELECTRIC  JOURNAL 


243 


back  into  the  furnaces.  With  a  slam  the  doors  fly 
shut  again  and  the  firemen  run  their  sHce  bars  through 
a  special  hole,  over  the  grating,  work  with  the  incan- 
descent mass,  and  pull  the  bars  back,  heated  in  that 
half  minute  to  a  white  heat.  That  is  the  way  it  goes  in 
every  one  of  eight  fire  rooms — eight  firemen  to  each 
room,  all  savagely  tossing  into  the  hungry  fui^naces  the 
coal  a  crew  of  coal  passers  haul  out  of  the  bunkers  in 
big  iron  buckets. 

The  heat  is  terrific,  and  when  a  furnace  opens  the 
fires  roar,  blown  to  a  fury  by  the  forced  draught. 
Each  fireman  has  to  protect  his  hands  by  a  cloth,  and 
sometimes  his  eyes  by  glasses,  and  occasionally  he  has 
to  jump  to  the  middle  of  the  room  for  a  brief  second  to 
get  a  gust  of  the  air  the  blowers  are  forcing  down  from 
the  decks  above. 

Then  a  call  comes  for  more  steam.  You  should 
see  the  shovels  fly  now !  The  air  becomes  obscure 
with  coal  dust.  Clack,  clack,  clack!  The  doors  fly 
shut  all  around.  The  men  toss  coal  like  mad.  They 
forget  the  heat,  their  thirst — some  are  losing  their 
hand  cloths.  They  trample  on  one  another's  feet, 
knock  one  another  with  buckets,  and  bars,  unheedful, 
for  the  steam  must  be  made  to  climb.  And  while  the 
hungry  engines  are  using  it  up,  the  wild  energ}-  of  the 
men  gains  a  surplus  and  the  pressure  goes  up — 220, 
225,  230  pounds ! 

That  is  something  like  what  happened  a  few  years 
ago  on  a  trial  trip.  Now  with  a  ship  almost  twice  is 
large,  twice  as  powerful  and  three  times  as  costly 
there  was  a  looking  forward  to  the  real  thrill  that  was 
about  to  be  furnished.  The  memory  of  the  excitement 
of  the  past  was  to  be  superseded  by  a  more  modern 
and  therefore  still  more  nerve  startling  hair  raiser. 
All  the  figures  available  pointed  that  way.  Here  was  a 
piece  of  propelling  machinery  designed  to  furnish  33- 
000  horse-power.  The  two  main  generators  when 
turning  at  top  revolutions  were  reputed  to  create 
enough  electricity  to  supply  about  thirty  of  the  or- 
dinary ship  lighting  systems.  The  four  motors  were 
supposed  to  be  about  as  powerful  as  sixteen  average 
size  freight  engines.  The  speed  of  the  turbines  was 
set  down  at  thirty-five  revolutions  per  second  and,  of 
course,  as  the  generators  were  hitched  directly  to  the 
turbines,  they  would  have  to  turn  at  this  same  dizzy 
rate.  The  prospects  for  a  pleasant  afternoon  were  de- 
cidely  good. 

Now,  the  whole  speed  trial  resolves  itself  into  .1 
series  of  various  runs  for  the  purpose  of  detenninlng 
the  number  of  revolutions  at  certain  speeds,  fuel  con- 
sumption at  various  speeds,  and  endurance  runs 
for  various  periods  of  time.  In  order  not  to  amelior- 
ate the  full  effect  of  what  was  in  store  and  see  onlv 
the  most  intense  part  of  the  trial,  the  Chief  was  con- 
sulted as  to  what  would  be  the  best  time  10  knock  off 
viewing  the  scenery  from  the  bridge  and  get  into 
the  turmoil  below.  "Oh.  by  all  means  wait  for  the 
four-hour   full-speed   run.     Then   vou'll    see   this   little 


marine  baby  at  her  best.  These  preliminary  runs  are 
nothing  at  all.  Don't  waste  time  on  them  if  you  are 
•looking  for  something  to  make  your  spine  curl.  The 
four-hour  full-speed  run  will  make  you  lose  a  couple 
of  nights'  sleep." 

That  sounded  good,  so  accordingly  I  curbed  the 
prancing  steeds  of  my  impatience  the  first  few  days, 
in  preparation  for  the  treat  I  was  to  have  later  on.  T 
must  say  it  was  not  a  very  difficult  thing  to  do.  There 
is  nothing  interesting  these  days  in  fifteen  knots.  That 
seems  to  be  nothing  more  than  what  the  ordinary 
speed  limits  permit  in  any  one  horse  village.  The  old 
Oregon  could  do  that.  But  twenty-one  knots  for  a 
battleship  like  the  Tennessee,  well,  that  was  a  dish  to 
tickle  the  palate  of  the  most  jaded  excitement  chaser. 

It  is  difficult  to  keep  tab  on  all  the  runs  that  a 
ship  makes  on  an  occasion  of  this  kind.  It  seems  that 
she  is  forever  turning,  and  tooting  her  whistle,  and  giv- 
ing stand-by  signals,  and  yelling  "mark!"  over 
the  loud  speaking  telephones,  and  steering  up  and  down 
over  that  measured  mile  so  accurately  designated  by 
pretty  little  white  towers  on  the  shore.  After  a  few 
days  of  it,  unless  you  are  directly  concerned,  you  lose 
almost  all  consciousness  of  it  and  forget  that  it  is 
going  on.  Especially  at  this  time  there  was  something 
lacking,  it  seemed.  Something  was  not  going  off  just 
according  to  the  accepted  standards  in  cases  like  this. 
An  ominous  lack  of  vibration  appeared  to  indicate  that 
some  trouble  was  being  encountered  and  that  the  old 
girl  was  not  walking  along  as  well  as  the  Chief  had 
hoped.  The  occasional  glimpses  obtained  of  the  Chief 
tended  to  confirm  this  opinion.  A  small,  slender  man 
with  a  sensitive  face,  he  looked  as  thougn  he  carried 
his  New  York  Navy  Yard  expression  still  with  him. 
I  felt  rather  sorry  for  him.  These  electrical  innova- 
tions, these  electric  drive  improvements  are  no  joke. 

At  a  rough  estimate  we  had  passed  the  big  hotel 
which  ornaments  the  outskirts  of  Rockland  so  beauti- 
fully, about  the  four  hundred  and  twentieth  time. 
Some  sea  gulls  were  gracefully  planing  through  the 
air  waiting  for  us  to  come  to  anchor.  The  weather 
was  perfect,  exactly  the  sort  of  a  day  for  an  automo- 
bile drive.  The  wooded  shore  looked  extremely  in- 
viting. I  was  just  calculating  the  cost  of  starting  from 
New  York  with  a  flivver  and  making  a  two  months 
cruise  along  this  strip  of  the  coast  when  a  messen- 
ger came  up  and  said  that  the  Chief  wanted  to  know 
whether  I  had  changed  my  mind  about  going  be''ow 
during  the  full-power  run. 

"Great  codfish !"  I  cried,  "do  you  mean  to  say  that 
the  full-speed  run  is  being  held  now — right  now?" 

"We  are  just  about  half  through  with  it,  sir,"  said 
the  polite  messenger. 

There  was  no  time  to  lose.  It  would  take  me  a 
little  while  to  get  dressed  and  there  was  a  good  deal 
to  see,  I  imagined.  No  time  was  wasted  getting  to  my 
room  and  peeling  ofl:  my  good  clothes  to  give  wav  for  a 


244 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


suit  of  dungarees.  Next  I  wrapped  up  my  neck  carfully 
with  an  old  neckerchief,  my  shoes  I  took  off  for  a 
pair  of  discarded  tennis  slippers,  my  sensitive  scalp 
I  protected  from  the  dripping  oil  by  means  of  a  white 
sailor  hat  whose  rim  had  been  torn  off,  and  to  com- 
plete my  outfit  I  dug  up  a  pair  of  automobile  glasses 
to  give  me  the  final  touch  of  protection  against  spurting 
steam,  dripping  hot  water,  and  splashing  oil.  Then 
I  crawled  down  a  hatch  on  the  main  deck  and,  at  the 
bottom  of  a  steep  ladder,  I  met  the  Chief. 

"I'm  glad  you  came,"  he  said,  "we  are  just  begin- 
ning to  hit  her  up  fine.  Now  you  follow  me  and  I'll 
show  you  all   there   is   to   see."     So   I    followed   him. 

"Here  we  are  in  the  forward  main  generator 
room,"  he  said,  "isn't  it  wonderful?  I  looked  around 
and  saw  a  big  cylindrical  steel  casing  set  off  here  and 
there  by  a  gauge  or  a  piece  of  stray  cable. 

"Where  is  your  electrician's  force?"  I  asked. 

"Over  there,"  indicated  the  Chief.  I  saw  a  couple 
of  men  in  neat  dungarees  idling  near  a  ladder.  "Seem 
to  be  nice  boys,"  I  remarked. 

"Oh  yes,"  replied  the  Chief,  "we  get  a  good  class 
of  men  in  the  navy.  Now  follow  me  and  I'll  show 
you  the  pump  rooms."  We  decended  another  iron  lad- 
der. Quite  a  number  of  pumps  seemed  to  be  gathererd 
here  and  some  men  were  wiping  pistons  with  waste. 
"These  are  the  pumps,"  explained  the  Chief. 

"You  have  lovely  pumps  on  this  ship,"  I  ventured. 

"Oh  yes,"  said  the  Chief,  "there  is  nothing  wrong 
with  the  pumps  on  this  ship.  Let's  go  into  the  motor 
rooms  now."  So  we  went  up  and  down  a  few  more 
ladders  and  finally  arrived  at  a  spacious  compartment, 
painted  immaculately  white  with  all  its  brass  and  cop- 
per pipes  and  fittings  shining  brightly. 

"This  is  the  inboard  motor  room.  I'here  are  two 
motors  like  this,  on  the  port  and  on  the  starboard  sides. 
Each  of  the  four  propellers  has  its  own  motor." 

I  saw  a  lot  of  cables  leading  up  from  the  center 
of  another  large  rotary  structure,  neatly  painted,  with 
a  few  openings  screened  off  with  a  fine  wire  mesh.- 
A  man  was  lolling  near  a  small  dial.  We  were  stand- 
ing on  a  grating,  dry,  polished,  of  artistic  design.  The 
air  was  fresh  and  cool. 

"Nice  place  for  a  quiet  afternoon's  study  or  a 
breath  of  fresh  air." 

"Oh  yes,"  said  the  Chief.  "We  have  a  pretty 
good  ventilating  system  on  this  ship.  Do  you  feel  like 
going  into  the  boiler  rooms." 

I  wanted  the  whole  works  or  none,  so  we  passed 
through  two  air  locked  doors  and  down  another  lad- 
der till  we  came  to  the  boiler  and  fire  room. 

"How  many  burners  have  you  lit?"  he  asked  a 
young  fellow  .standing  watch  over  an  indicator.  "Four, 
sir,"  came  the  response. 

"They're  holding  two  in  reserve,"  commented  the 
chief. 

"The  oil  seems  to  burn  well,"  I  annotated. 

"Oh  yes,"  said  the  Chief,  "once  you  get  your 
burners  spraying  well  and  keep  five  or  six  inches  air 


pressure  in  the  firerooms,  there's  nothing  to  it.  I  guess 
we'd  better  take  a  look  at  the  control  room  now." 

We  made  our  way  along  several  narrow  passage- 
ways and  finally  entered  the  control  room  through  a 
small  door.  This  was  a  long  narrow  space  running 
athwartships.  From  a  line  running  through  the  cen- 
ter of  it  rose  a  dozen  or  so  of  long  levers.  On  the 
bulkhead  facing  them  were  several  dozen  indicator 
dials,  gauges,  clocks,  and  various  recording  instru- 
ments. A  few  officers  dressed  in  neat  white  collars 
and  some  civilians  were  watching  the  different  hands 
and  pointers. 

"This  is  the  vital  part  of  the  ship,"  said  the  Chief, 
"here  all  the  movements  of  the  ship  are  controlled." 
Some  of  the  officers  and  civilians  seeing  me,  moved  to 
one  side  as  if  afraid  of  getting  dirty.  It  reminded  me 
that  I  was  rather  alarmingly  dressed.  The  goggles  I 
had  discarded  some  time  back. 

"These  gentlemen  seem  very  much  interested  in 
their  work.  We  are  probably  disturbing  them.  Let 
us  go  and,  as  the  time  seems  to  be  flying,  let  us  get 
down  to  cases  and  proceed  directly  to  the  most  excit- 
ing spot — where  the  tension  of  the  full  power  run  is 
at  its  greatest — where  men  are  working  with  over  taut 
nerves — where  the  activity  of  the  mechanism  is  fo- 
cussed  to  its  greatest  speed,  where" — the  Chief  looked 
at  me  in  amazement. 

"Why,  we  were  in  the  main  generator  room  an 
hour  ago.  There  is  nothing  left  to  show  you.  Besides 
the  run  is  almost  completed.  They  told  me  in  the  con- 
trol room  we  haven't  gone  below  twenty-one  knots  .so 
far." 

He  started  away  and  I  followed.  On  the  way  out 
I  saw  a  man  carrying  an  oil  can. 

"Wait  a  minute,  young  fellow,"  I  said,  "lend  me 
your  can  for  a  second."  I  took  it  and  squirted  a  few 
jets  over  my  shoes,  on  my  coat,  and  rubbed  a  little 
on  my  hands  and  face.  Then  I  went  up  to  my  room 
and  removed  my  oil  drenched  overalls.  After  I  was 
dressed  again  in  my  normal  belongings  I  stepped  out 
on  the  deck.  The  Chief  was  just  coming  down  from 
the  bridge.  His  face  wore  a  smile.  "The  run  is 
finished.  Everything  went  fine.  Gosh,  but  I'm  glad 
it's  over.  I  can't  stand  the  excitement  of  it  like  I  could 
formerly.  But  the  romance  of  it — ah,  that  I  guess  I'll 
never  lose.  Wasn't  it  wonderful  below — all  that  pon- 
derous, gigantic  mechanism  grinding  out  the  power  to 
shoot  this  ship  through  the  water  twenty-one  point 
zero  two  knots  per  hour.     Collossal !" 

"Great  hiccoughing  hyena!"  I  gasped,  "let  me 
have  air !"  In  an  instant  I  was  up  on  the  bridge.  The 
officer  of  the  deck  was  taking  a  bearing.  "Do  you 
mind  if  I  stay  up  here  and  watch  the  scenery  move  by? 
I  love  excitement — the  thrill  of  motion.  It's  great  up 
here." 

"Go  to  it,"  he  grunted,  "but  if  you're  looking  for 
excitement,  the  thrill  of  motion  as  you  call  it,  why  in 
the  devil  didn't  you  go  below  while  they  were  making 
their  full  power  run?" 


12  Maciiiiiory 
of  tli^  ^J.  S,  S.  ToHj[ios5©e 


W.  E.  THAU 

General  Engineer, 
Wcslinghouse  Electric  &  Mfg.  Company 


ALTHOUGH  the  Tennessee  is  the  second  battle- 
ship to  have  electric  propelling  machinery,  it  is 
the  first  to  realize  the  full  advantages  of  the 
electric  system  of  propulsion  in  regard  to  arrangement 
of  machinery.  The  ship  has  a  displacement  of  approxi- 
mately 33  ooo  tons ;  a  length  overall  of  624  feet,  and  a 
breadth  of  97  ft.,  3.5  inches  on  the  load  water  line.  The 
normal  full-load  speed  is  21  knots  and  the  calculated 
horse-power  under  this  condition  is  28  000. 

The  Tennessee's  armament  consists  of  a  main  bat- 
tery of  twelve  14  inch  guns;  a  secondary  battery  of 
fourteen  5  inch  guns,  four  3  inch  anti-aircraft  guns, 
four  6-pounders  for  saluting,  and  two  21  inch  sub- 
merged torpedo  tubes. 


is  sufficient  to  supply  the  excitation  and  auxiliary  load 
just  mentioned. 

The  power  generating  machinery  is  located  in  two 
engine  rooms,  one  being  forward  of  the  other,  and  both 
forward  of  the  control  room.  The  turbogenerators 
are  mounted  directly  above  the  condensers.  In  each 
engine  room,  there  are  two  300  kw  geared  turbine  con- 
densing, and  one  non-condensing  direct-current  sets 
of  the  three-wire  type,  supplying  power  at  240  and  120 
volts.  These  sets  are  mounted  on  the  same  flat  as  the 
main  turbogenerator  sets,  as  is  also  the  motor  genera- 
tor booster.  The  condenser  with  its  auxiliaries  is  lo- 
cated in  the  lower  machinery  flat  or  pump  room,  di- 
rectly  rmderneath   the   main   generators.     The   switch- 


^- 


'  FIG.   I — UNITED  bTATES  BATTLESHIP  TENNNESSEE 


The  propellers  are  driven  by  four  direct-connected, 
two-speed,  wound-secondary  induction  motors,  supplied 
with  three-phase  power  through  suitable  control  equip- 
ment at  approximately  3400  volts,  and  34.6  cycles,  (full 
speed)  by  two  direct  connected  2075  r.p.m.  turbogen- 
erators. A  battery  of  eight  oil-fired  water  tube  boilers 
supplies  steam  to  the  turbines  at  280  lbs.  gage  at  the 
boilers.  The  generators  are  excited  from  one  of  the 
300  kw  direct-current  geared  turbine  auxiliary  sets, 
through  a  booster  so  designed  as  to  vary  the  240  volt 
bus  voltage  in  either  direction  to  a  value  best  suited 
for  the  given  condition.  All  engine  room  auxiliaries 
necessary  to  the  main  propulsion,  such  as  the  main  and 
auxiliary  condenser,  .circulating  and  condensate  pumps, 
the  lubricating  and  governor  oil  pumps,  oil  cooler  cir- 
culating pumps,  and  the  main  motor  ventilating  blowers 
are  driven  by  direct-current  motors  supplied  with 
power  from  the  same  generator  which  is  used  for  ex- 
citation.    One  auxiliary  generator  in  each  engine  room 


boards  for  the  300  kw  sets  are  located  at  the  ends  of  the 
engine  rooms. 

The  control  room  contains  all  the  control  equipment 
and  other  apparatus  necessary  for  the  complete  control 
of  the  propelling  machinery  and  is  located  aft  of  the  af- 
ter engine  room  and  between  the  two  outboard  motor 
rooms.  The  inboard  motors  are  in  what  is  known  as 
the  center  motor  room,  located  directly  aft  of  the  con 
trol  room.  All  of  the  main  machinery  is  located  in 
separate  water  tight  rooms,  as  shown  in  Fig.  2. 

The  cables  connecting  the  units  of  the  main  pro- 
pelling machineiy  are  of  the  three-conducior,  lead  cov- 
ered type.  There  are  a  sufficient  numDer  of  these 
cables  in  parallel  to  carry  the  maximum  power  safely. 
The  cable  ends  are  provided  with  pot  heads  forming 
water-tight  seals  from  which  the  respective  conductors 
are  brought  out  and  connected  to  well-insulated  bus 
structures  located  over  the  switches  in  the  control  room, 
and  at  the  motors  and  generators. 


246 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


From  maximum  speed  down  to  a  speed  slightly 
in  excess  of  16  knots,  two  generators  are  used,  and  the 
motors  are  connected  to  the  24  pole  winding.  Speeds 
below  this  are  obtained  with  only  one  generator  in  op- 
eration and  the  motors  connected  to  either  the  24  or 
36  pole  winding.  Speeds  up  to  and  including  15  knots 
can  be  obtained  with  the  motors  connected  to  the  36 
pole  winding. 


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windings  that  have  been  given  special  consideration  to 
guard  against  the  deleterious  effect  of  salt  and  moisture 
conditions.  The  insulation  is  of  the  best  known  ma- 
terial and  is  applied  and  treated  in  accordance  with 
thoroughly  tried  methods. 

The  mechanical  construction  of  the  moior  is  of  the 
self-contained  type,  in  which  the  bearings  are  carried 
by  suitable  brackets  which  fit  into  recesses  m  the  stator 
frame.  The  entire  motor  is  supported  by  feet  cast  in- 
tegral with  the  frame  on  either  side.  The  bearing 
housings  are  adjustable  radially  by  means  ot  jack  screws 
in  the  brackets  and,  after  being  adjusted,  are  bolted 
rigidly  to  the  bracket. 

The  ventilation  is  supplied  by  duplicate  direct-cur- 
rent, motor-driven  exhaust  blowers,  each  capable  of 
delivering  12  500  cubic  feet  per  minute  maximum.  In 
addition  to  these  separate  blowers,  the  rotor  itself  is 
provided  with  fan  vanes  which  assist  in  the  ventilation, 
and  which  are  capable  of  supplying  sufficient  air  to  en- 
able the  motors  to  be  operated  for  brief  periods  at  full 
load  in  case  of  failure  of  the  blowers.  The  blowers  are 
mounted  on  the  top  of  the  motors,  and  draw  the  air 
through  the  motor  and  discharge  it  through  suitable 
ducts  to  the  deck.  The  system  of  ventilation  consists 
of  the  axial  flow  of  air  through  the  core  and  end  wind- 
ings, the  air  being  drawn  in  through  openings  in  the 
brackets  and  discharged  through  a  radial  duct  at  the 
middle  of  the  core  to  an  outlet  at  the  top  of  the  motor, 
and  from  there  to  the  deck. 

In  order  to  get  at  the  motors  for  inspection  and 
repair,  suitable  tracks  and  disassembling  gear  are  pro- 
vided, so  that  the  stator  can  be  moved  to  clear  the  rotor 
windings. 

JIAIN   GENERATORS 

Each  main  generator  is  capable  of  delivering  a  max- 
imum of  15000  kv-a  at  approximately  30.5  cycles. 
The  generators  are  designed  and  constructea  In  accord- 
dance  with  standa^-d  land  practice,  except  that  the  ro- 
tor is  of  the  totally  enclosed  type.  The  stator  coils  are 
insulated  in  the  same  manner  as  the  motor  coils. 

The  air  for  ventilating  the  generators  is  supplied 
to  the  machinery  space  by  means  of  separate  ventilat- 


FIG.    2 — PROPELLOR   PERFORMANCE   CURVES 

By  providing  two  sets  of  windings  on  the  motors, 
it  is  possible  to  obtain  more  economical  operation  at  low 
speeds  than  would  be  the  case  with  a  single  winding. 
As  the  propeller  speeds  are  adjusted  by  regulating  the 
speed  of  the  turbines,  the  two-winding  arrangement  per- 
mits the  turbines  to  be  operated  at  high  speeds  over  the 
cruising  range  as  well  as  the  full  speed  range,  thus  re- 
sulting in  better  economy. 

MAIN    MOTORS 

Each  main  propelling  motor  is  capable  of  deliver- 
ing a  maximum  of  8375  hp,  at  a  speed  of  about  185 
r.p.m.     They  are  of  the  induction  type  and  are  wound 
for  two  speeds  at  full  frequency,  there  being  a  24  pole 
and  a  36  pole  winding.     The  primary  or  stator  has  two 
independent    windings,     one    for    each 
set   of   poles.     The  rotor  has  a   three- 
phase,       two-parallel       star-connected 
winding    having    balancer    connections 
operating  as  such  on  the  24  pole  wind- 
ing.    The    24   pole    winding    is     con- 
nected to  three  slip  rings.     When  the 
stator    is    connected    to    the    36    pole 
winding,      the     balancer     connections 
form  short-circuit  paths  for  the  rotor 
conductors,  thus  forming  an  ordinary 

,  .       ,.  ,  .  ,  'Propelling  Motor 

squirrel-cage    wmdmg    havmg    straps 

....  .  ,  FIG  3— SCHEM.MIC  PLAN  OF  ARRANGEMENT  OF  PROPELLING     MACHINERY 

mstead  of  resistance  nngs  to  connect 

the  rotor   conductors   togetlier.  ing  blowers.     The  air  is  drawn   from  the  lower  ma- 
in general,  the  design  of  the  motors  follows  stan-  chinery  space  through  an  inlet  at  the  bottom  of   the 
dard  land  practice.  There  are,  however,  certain  features,  generator,  through  the  end  bells,  entering  the  machine 
particularly   in   connection   with   the   insulation   of   the  ai  each  end   of    the    rotor.     From    there,    it    is    forced 


Secx>ndarv  Cir.  Bkr,  Structure 

and  Liquid  Rheostats 
.  Primary  Cir.  Bkr.  Structure 


D.  C  Turbogenerator  Set' 


June,  1921 


THE  ELECTRIC  JOURNAL 


247 


through  the  end  windings,  core  and  air-gap  axially, 
and  discharged  radially  through  a  central  opening  in 
the  core,  from  whence  it  passes  through  a  duct  to  the 
deck. 

The  rotor  consists  of  a  solid  steel  forging  having 
radial  slots  for  receiving  the  windings.  The  winding 
consists  of  a  series  of  turns  of  bare  copper  strap  and 
the  insulation  is  entirely  mica  and  asbestos.  After 
winding,  the  coils  are  very  substantially  braced,  in  order 
to  prevent  any  possible  movement. 

The  main  motors  and  the  generators  are  each  pro- 
vided with  thermocouples  for  measuring  the  hot  spot 
temperature.  These  thermocouples  are  all  connected 
to  a  potentiometer  board  in  the  control  room. 

In  order  to  prevent  the  motors  and  the  generators 
from  sweating  when  idle,  heaters  are  provided,  the  mo- 
tors being  warmed  electrically  and  the  generators  by 
steam  coils.     These  coils  are  so  located  as  not  to  cause 


FIG.  4 — ST.\RBO..VRD  INBO.'\RD  PROPELLING  MOTOR 

local  heating  and  all  joints  and  connections  to  the  coils 
are  made  outside  of  the  frame  of  the  machine  to  avoid 
the  possibility  of  steam  leaks  into  the  machine. 

TURBINES 

The  turbine  is  of  the  combined  impulse  and  reaction 
semi-double-flow  type,  allowing  complete  expansion  of 
the  steam  in  one  cylinder.  An  exhaust  connection  is. 
provided  at  each  end  of  the  turbine. 

The  speed  is  regulated  b}-  the  governor  valve  only, 
hand  valves  being  used  merely  to  obtain  the  best  econo- 
my and  to  prevent  overloading  the  boilers  at  the  various 
standard  speeds. 

Briefly,  the  speed-control  system  consists  of  a 
governor  driven  directly  from  the  turbine  shaft 
through  suitable  gearing.  The  governor  is  essentially 
;.  dead  weight  governor,  in  which  the  dead  weight  is 
replaced  by  a  hydraulic  piston,  resulting  in  a  type  of 


governor  capable  of  functioning  over  a  wide  range  of 
speed  by  varying  the  hydraulic  pressure  on  the  piston. 
The  speed  is  adjusted  hydraulically  by  means  of  a 
control  valve  in  the  main  control  room  which  regulates 
the  oil  pressure.  A  double-seated  poppet  valve  located 
on  the  main  steam  inlet  to  the  turbine  is  controlled 
through  a  floating  lever  oil  pressure  relay  system  from 
the  main  governor,  and  this  valve  controls  the  amount 
of  steam  as  required  to  maintain  the  speed  for  which 
the  system  is  set.  The  governor  control  valve  is  also 
operated  through  a  suitable  oil  pressure  relay  by  a 
separate  over-speed  governor  secured  to  the  end  of  the 
turbine  shaft.  In  addition,  this  over-speed  governor 
also  operates  the  main  throttle  valve,  in  case  of  neces- 
sity. 

In  order  to  limit  the  power  input  to  the  turbine  on 
overload  conditions  to  an  amount  which  will  prevent 
excessive  overloads  on  the  machinery  and  also  prevent 
priming  of  the  boilers,  a  power  limit  stop  is  provided. 
This  is  arranged  to  limit  the  travel  of  the  governor  link- 
age  in  the   direction   which   admits  more   steam.     The 


FIG.   .S — ENGINE  ROOM   .\ND  MAIN  GENERATOR 

position  of  the  stop  is  adjusted  electrically  from  the 
main  control  room  through  a  system  of  gearing  operated 
by  a  small  motor.  In  order  that  the  operator  may  know 
the  position  of  the  power  limit  stop  at  any  instant,  an 
electrical  position  indicating  system  is  provided,  the 
transmitter  of  which  is  driven  by  spur  gearing  from  the* 
power  limit  stop  mechanism.  The  indicator  is  mounted 
in  the  control  room. 

In  operation,  this  system  functions  as  follows: — 
The  speed  of  the  ship  is  set  from  the  control  room  for 
any  given  standard  by  means  of  the  hydraulic  speed- 
,  control  system.  The  power  limit  stop  is  then  adjusted 
to  limit  the  motor  speed  to  a  few  revolutions  above  that 
corresponding  to  the  standard  speed.  Should  an  over- 
load occur  from  turning  or  from  any  other  cause,  the 
speed-control  governor  will  tend  to  maintain  a  constant 
speed  by  admitting  more  steam.  However,  as  the  gov- 
ernor linkage  has  only  an  additional  limit  of  travel  cor- 
responding to  the  few  revolutions  increase  in  motor 
speed,  the  steam  which  can  be  admitted  to  the  turbine 
is  therefore  limited,  and  consequently  the  overload  has 
a  fixed  value  for  anv  given  condition. 


248 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


The  power-limit  stop  may  also  be  used  for  adjust- 
ing the  speed  of  the  turbine  below  any  vatue  for  which 
the  main  speed  governor  system  is  set,  ana  it  accom- 
plishes this  in  a  manner  similar  to  throttling.  Since 
the  speed  is  a  function  of  the  oil  pressure,  oil  gauges 
mounted  in  the  control  room  give  a  further  check  on 


FIG.  6 — 300  K\V  DIRECT-CURRENT  GEARED  TURBINE  SET 

the  proper  functioning  of  the  entire  turbine  control  sys- 
tem. The  over-speed  stop  may  be  operated  from  the 
over-speed  governor,  hand  trip  in  tlie  engine  room  or 
by  wire  pull  from  the  control  room. 

The  turbine  and  generator  bearings  have  forced 
lubrication.  Oil  for  the  governor  control  system  is  also 
supplied  from  the  same  system.  The  oil  is  delivered  to 
the  governor  system  at  80  lbs.  pressure  and  to  the 
bearings  at  5  to  10  lbs.  pressure  through  a  reducing 
valve.  The  oil  pumps  for  circulating  this  oil  are  of  the 
positive  displacement  rotary  type.  Two  pumps  are 
provided  in  each  engine  room,  one  of  which  is  motor 
driven  and  the  other  turbine  driven,  the  latter  standing 
by  as  a  spare.  However,  upon  failure  of  the  motor- 
driven  pump  from  any  cause,  an  arrangement  of  pi?- 
tons  operated  by  the  oil  pressure  will  automatically 
caluse  the  turbine-driven  pump  to  be  placed  in  opera- 
tion. The  turbine-driven  pump  is  provided  with  a  con- 
stant speed  governor  and  an  overspeed  stop. 

MAIN  CONTROL 

As  in  the  case  of  any  other  drive,  the  control  for 
the  electric  drive  is  operated  under  orders  from  the 
bridge.  All  controlling  apparatus  necessary  for  the  op- 
eration of  tlie  propelling  machinery  is  located  in  the 
control  room,  and  all  operations  for  the  control  of  the 
ship  are  effected  in  this  room,  except  the  actual  star'.- 
ing  of  the  turbines.  The  circuits  are  handled  by  means 
of  manually-operated  oil  circuit  breakers.  All  circuit 
breakers  are  of  sufficient  capacity  to  open  the  circuits 
under  full  power  and  voltage  conditions,  althou.^'h 
in  normal  operation,  circuit  breakers  are  not  opened  or 
closed  under  load.  They  are  manually  operated  from 
levers  which  are  located  directly  in  front  of  the  con- 
tront  room  switchboard,  and  arranged  so  that  the  opera- 
tor faces  forward.     These  levers  are  interlocked  so  thnt 


improper  operation  is  impossible.  The  primary  cii- 
cuit  breakers  are  arranged  in  two  rows  athwart  ship 
having  an  aisle  betweeti  them  for  inspection  and  repair, 
if  necessary.  The  secondary  short-circuiting  breakers, 
and  the  liquid  rheostats  for  controlling  the  motor  sec- 
ondaries, are  located  back  of  the  operating  aisle. 

In  order  to  disconnect  any  circuit  completely,  self- 
contained  disconnecting  devices  have  been  provided  on 
the  reverser  circuit  breakers,  generator  circuit  break- 
ers, and  tie  circuit  breakers.  The  mechanism  is  so 
arranged  that  the  circuit  breaker  must  be  opened  before 
it  is  possible  to  disengage  the  disconnecting  device.  This 
provision  safe-guards  the  men  in  case  of  improper  or 
faulty  operation,  and  at  the  same  tinte  makes  it  possible 
to  inspect  or  repair  a  circuit  breaker  while  the  ship  is 
under  way. 

The  levers  operate  the  circuit  breakers  and  rheostat 
valves  in  pairs,  and  are  arranged  in  a  single  row,  di- 
rectly aft  of  the  circuit  breaker  structure.  The  ar- 
rangement is  symmetrical  so  that  levers  on  the  left  of 
the  central  position  operate  the  circuit  breakers  in  the 
after  generator  and  port  motor  circuits,  while  those  on 
the  right  of  the  central  position  operate  the  circuit 
breakers  which  control  the  circuits  of  the  forward  gen- 
erator and  starboard  motors.  The  pedestals  on  which 
the  turbine  control  valves  are  mounted  ana  tlie  genera- 
tor field  switch  levers  are  located  in  the  center  of  the 
group.  All  the  levers  are  mechanically  interlocked  so 
as  to  insure  the  proper  sequence  of  operation.  The 
scheme  of  interlocking  is  such  that  the  field  must  be  off 
and  the  steam  control  reduced  to  a  low  setting  before 
any  of  the  above  circuit  breakers  can  be  operated. 

With  two  generators  in  operation,  the  control  of  the 
port  and  of  the  •tarboard  side  of  the  ship  .11  r  independ- 


jlC     7_GEXER.-\L   VIEW   OF   CONTROL   ROOM 

ent.  With  the  tie  circuit  breaker  closed  and  one  gen- 
erator in  operation,  the  direction  of  rotation  of  port  and 
starboard  screws  may  be  in  the  same  or  opposite  direc- 
tions, but  of  necessity  must  be  at  equal  speeas. 

All  starting  and  maneuvering  is  done  with  the  24 
pole  connection.  When  the  motors  are  thus  connected 
the    secondaries   are    controlled  by    means   of    liquid 


June,  1921 


THE  ELECTRIC  JOURNAL 


249 


rheostats.  There  is  one  double  rheostat  for  the  port 
motors  and  one  for  the  starboard  motors.  The  rheo- 
stat consists  essentially  of  a  two-compartment  tank,  the 
lower  compartment  of  which  serves  as  a  reservoir  foi- 
the  electrolj'te  and  also  as  a  container  for  the  cooling 
coils,  while  the  upper  compartment  contains  the  elec- 


— 130 
— 120 

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FIG.  8 — LOAD  ON  GENERATORS  WHEN  TURNING  WITH  35  DEGREE 
RUDDER 

Power  limit  not  set. 

trodes.  When  it  is  desired  to  use  a  rheostat,  the  valve 
in  the  upper  compartment  is  closed  by  means  of  a  lever 
operated  from  the  control  stand,  thus  allowing  the  liquid 
to  rise  in  the  upper  compartment.  After  the  maximum 
level  has  been  reached,  the  motor  secondary  is  complete- 
ly short-circuited  by  means  of  an  oil  circuit  breaker 
which  is  operated  by  a  lever  from  the  control  stand. 

OPERATION 

The  problem  involved  in  designing  equipment  for 
battle  ship  propulsion  is  entirely  special,  and  quite  dif- 
ferent from  that  encountered  in  designing  land  power 
plants.  The  generators,  turbines,  motors  and  control 
must  be  considered  as  a  unit,  and  due  regard  given  to 
the  requirements  of  the  propeller.  The  starting  and 
running  requirements  under  normal  sea  conditions  are 
not  severe,  as  the  power  required  is  practically  steady. 
In  a  rough  sea,  the  power  varies  considerably  and  is  un- 
steady. The  most  severe  conditions,  however,  are  ob- 
tained during  reversal  and  during  turning,  and  if  pre- 
cautions are  not  taken  to  limit  the  power  output  of  the 
turbine,  it  is  possible  to  impose  large  overloads  on  the 
machinery  during  the  latter  condition.  Fig.  8  shows 
the  manner  in  which  the  inboard  and  outboard  sides 
vary  when  making  a  turn  with  a  35  degree  rudder.  By 
"inboard"  side  of  the  turn  is  meant  the  side 
toward  the  center  of  the  circle  described.  The  particu- 
lar curve  shown  has  been  interpolated  from  tests  made 
on  a  modern  battleship  making  19  knots  and  turning 
with  a  35  degree  right  rudder.  The  test  in  this  in- 
stance was  made  without  setting  the  power  limit  stop 
and  the  turbines  were  allowed  to  take  any  load  which 
may  be  imposed  up  to  the  maximum  capacity  of  the' 
machine.  It  will  be  noted  that  the  power  of  the  .gen- 
erator supplying  the  inboard  side  increases  rapidly  dur- 
ing   the    first    50   seconds,    at    which    point    it    reaches 


the  maximum  output  of  the  turbine.  The  power  de- 
livered by  the  outboard  turbine,  however,  decreases 
rather  rapidly  during  the  first  40  seconds,  and  then  be- 
gins to  increase  rapidly  until  a  constant  value  is 
reached  at  about  90  seconds.  An  analysis  of  the 
curve  shows  that  the  inboard  side  developed  an  over- 
load of  approximately  45  percent  when  the  maximum 
power  of  the  turbine  was  reached  and  that  the  inboard 
side  dropped  to  about  75  percent  normal  at  the  end  of 
the  first  40  seconds  and  then  increased  to  a  value  cor- 
responding to  approximately  15  percent  overload  at 
the  end  of  90  seconds,  when  the  power  became  con- 
stant. These  conditions  are  common  to  all  ships,  but 
vary  in  the  relative  proportions  of  overload. 

It  is  evident  that,  if  precautions  are  not  taken  to 
prevent  such  overloads  being  imposed  on  the  machinery, 
it  would  be  necessary  to  carry  sufficient  excitation  on 
the  generators  continuously  to  take  care  of  these  over- 
loads. At  reduced  loads,  it  would  be  possible  to  car- 
ry this  additional  excitation,  but  it  would  result  in  un- 
economical operation.  To  provide  for  similar  condi- 
tions at  the  maximum  loads  would  necessitate  an  un- 
warranted reserve  capacity  in  the  generator  fields,  thus 
resulting  in  larger  generators  than  needed.  However, 
to  overcome  this  condition,  a  form  of  power  limit  stop 
is  provided,  the  function  of  which  is  to  limit  the 
amount  of  steam  taken  by  the  turbine  to  a  predetermined 
value,  which  under  normal  operating  conditions  cor- 
responds to  an  overload  of  about  ten  percent.  By  thus 
limiting  the  amount  of  load  that  can  be  taken  by  the 
turbine,  and  consequently  the  generator,  the  field  ex- 
citation can  be  reduced  to  a  value  just  sufficient  to  main- 
tain  the   generator  voltage   safely   under   the   overload 


\ 

1 

1 

1 

I 

Full 

Loa( 

1  R   t 

M 

-8 

3      -6 

D      -4 

D      -2 

' 

i 

3        4 

'        ' 

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FIG.   9 — PROPELLOR  TORQUE  CHARACTERISTICS 

When  reversing  the  propellor  with  the  ship  going  ahead  at 
full  speed. 

condition.  The  only  effect  of  thus  limiting  the  power 
is  a  slight  and  inappreciable  slowing  down  of  the  ship 
during  such  maneuvers.  The  economy  gained,  how- 
ever, is  of  considerable  advantage. 

The  shape  of  the  turning  curves  and  the  overload 
obtained  varies  with  different  ships,  as  also  does   the 


25° 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


relative  excitation  to  be  carried  on  the  generators.  It 
is,  tlierefore,  necessary  to  conduct  a  series  of  "drop  out" 
tests  on  each  ship  in  order  to  determine  the  minimum 
safe  field  current  which  should  be  carried  continuously 
to  enable  the  ship  to  be  maneuvered  without  liability 
of  the  motors  and  generators  pulling  apart.  Ordinarily, 
motors  of  normal  design  have  inherent  torque  charac- 
teristics which  are  sufficient  to  cope  with  these  condi- 
tions, providing  the  generator  voltage  holds  up,  but 
since  it  is  a  characteristic  of  the  generator  voltage  to 
suddenly  break  on  abnormal  loads,  the  condition  is  pure- 
ly one  related  to  the  generators. 


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FIG.   10 — PROPELLING  MOTOR  SPEED-TORQUE  CHARACTERISTICS 

A — 24  pole  connections,  with  wound  secondary  short  cir- 
cuited. A-i ;  A-2;  A-3 — 24  pole  connections,  with  external 
secondary  resistance.  B — 36  pole  connections,  squirrel-cage 
secondary  winding. 

In  order  to  provide  indication  of  the  condition  of 
stable  or  unstable  operation,  stability  indicators  are  ar- 
ranged in  the  generator  circuits.  As  these  instruments 
indicate  the  relative  ratio  of  generator  armature  current 
and  voltage,  they  will  indicate  clearly  when  the  point  of 
voltage  collapse  is  being  approached. 

Another  condition  involving  tlie  correct  perform- 
ance of  generator,  motor  and  control  is  that  which  ex- 
ists during  reversal.  These  conditions  are  shown  in 
Fig.  9.  The  relative  proportions  of  these  curves  also 
depend  upon  the  ship  in  question,  but  the  curves  shown 
can  be  considered  as  typical  of  the  backing  conditions. 
For  the  sake  of  clearness,  the  reversing  curve  and  the 


motor  speed  torque  characteristics  have  been  shown 
separately.  As  the  motor  is  of  tlie  wound  secondary 
type  with  adjustable  external  resistance,  it  is  possible 
to  vary  the  torque  curves  to  suit  the  operatmg  condi- 
tions. Furthermore,  since  the  rheostat  is  of  the  liquid 
type,  it  is  possible  to  get  an  infinite  numoer  of  speed- 
torque  curves.  A  few  typical  speed-torque  curves 
have  been  drawn  for  diflferent  values  of  secondary  re- 
sistance. An  inspection  of  Fig.  9  will  show  that  the 
speed  of  the  propellers  drops  to  approximately  75  per- 
cent when  the  power  is  taken  off.  At  this  point,  the 
motor  connections  are  reversed,  and  the  motors  caused 
to  produce  a  torque  opposing  the  turning  effort  pro- 
duced by  the  motion  of  the  ship  on  the  propellers.  It 
will  be  noted  that,  as  the  r.p.m.  of  the  propellers  de- 
crease, the  opposing  torque  builds  up  to  approximately 
full  load  value  at  40  percent  ahead  revolutions  and  then 
decreases  to  approximately  35  percent  when  the  pro- 
pellers are  brought  to  a  stand-still.  As  the  propellers 
are  reversed,  the  torque  increases  rapidly  and  reaches 
full  load  value  at  40  percent  r.p.m.  in  the  backing  di- 
rection. The  above  discussion  is  based  on  maintaining 
full  speed  of  the  ship.  Under  actual  conditions,  how- 
ever, the  ship  slows  down  considerably  in  the  time  taken 
to  reach  40  percent  r.p.m.  in  a  backing  direction,  and 
therefore  higher  rotational  speeds  of  the  propellers  in 
the  backing  direction  can  be  obtained  before  reaching 
full-load  torque. 

The  most  vital  part  of  the  curve  is  that  at  about 
40  percent  of  full  load  speed  when  bringing  the  propel- 
lers to  a  stop  condition.  In  the  case  of  wound-rotor 
motors,  this  condition  presents  no  difliculties,  as  it  is 
possible  to  obtain  torques  considerably  in  excess  of  nor- 
mal full-load  torque  at  any  speed  by  simply  adjusting 
the  external  resistance.  The  generators,  however, 
must  have  sufficient  field  capacity  to  furnish  the  voltatje 
required  to  maintain  the  torque  under  the  conditions 
stated.  In  the  case  of  squirrel-cage  motors,  however, 
it  would  be  necessary  to  introduce  special  designs,  to 
obtain  speed-torque  curves  which  would  enable  the  mo- 
tor to  deliver  torque  safely  in  excess  of  the  requirement.- 
under  the  conditions  of  operation  described. 

All  such  conditions,  of  course,  must  be  taken  into 
account  in  designing  the  propelling  equipment  and  it 
is  obvious  that  turbines,  generators,  motors  and  control 
must  be  designed  as  a  unit  in  order  that  each  will  have 
characteristics  which  are  sufficient  to  enable  all  parts 
of  the  equipment  to  function  properly  under  the  re- 
quired conditions. 


\\Q 


11.  L.  BARNHOLOT 

Motor  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


IN  THE  type  of  ship  propelling  machinery  employ- 
ing steam  turbine  driven  alternating-current  gen- 
erators and  propelling  motors  it  is  possible  to  ob- 
tain all  the  speeds  necessary  to  maneuver  the  ship  by 
smiply  adjusting  the  speed  of  the  turbine,  thus  changing 
the  generator  frequency  and  the  speed  of  the  motors. 
Since  these  motors  form  the  only  load  for  the  genera- 
tors, varying  the  primary  frequency  is  entirely  feasible, 
although  by  this  metliod  the  steam  economy  becomes 
poor  at  the  lower  speeds.  This  is  not  a  serious  draw- 
back in  case  of  passenger  liners,  cargo  boats,  etc.,  which 
usually  run  at  their  top  speed  and  for  such  ships  that 
method  of  speed  control  is  thoroughly  practicable  and 
economical.  For  warships,  however,  the  requirements 
are  different,  and  in  the  case  of  capital  ships,  the  speci- 
fications of  the  U.  S.  Navy  Department  call  for  the 
maximum  attainable  steam  economy  at  one  lower  speed 
for  use  in  long  distance  cruising  as  well  as  at  full  speed. 
The  importance  of  economy  at  lower  speeds  in  the  case 
of  a  battleship  becomes  apparent  when  we  consider  that 
the  power  taken  by  the  propellers  varies  approximately 
as  the  third  power  of  the  ship's  speed,  so  that,  for  ex- 
ample, if  the  same  steam  consumption  per  shaft  horse- 
power could  be  maintained  at  half  speed  as  at  full  speed, 
the  ship  could  travel  four  times  the  distance  at  half  speed 
that  she  could  at  full  speed  using  the  same  amount  of 
fuel.  The  two  speeds  in  question  for  the  U.  S.  S.  Ten- 
nessee and  the  six  other  battleships  of  her  class  were  set 
u'  21  and  15  knots  respectively,  and  since  for  reasons 
of  steam  economy  it  was  essential  to  operate  the  tur- 
bine at  or  near  its  full  speed  under  both  of  these  condi- 
tions, an  induction  motor  having  two  synchronous 
speeds  was  adopted  as  the  only  logical  solution.  A  pole 
combination  of  24  and  36  poles  was  chosen,  which  cor- 
responds to  propeller  speeds  at  21  and  15  knots,  both 
being  obtained  with  practically  full  speed  on  the  turbine. 
This  pole  combination  also  permitted  the  use  of  a  type 
of  rotor  winding,  as  described  later,  by  means  of  which 
both  numbers  of  poles  were  obtained  with  a  single  wind- 
ing connected  to  three  slip  rings. 

PROPELLER  TORQUE  CHARACTERISTICS 

Aside  from  the  question  of  fuel  economy  when  the 
ship  is  under  way,  there  are  also  certain  vital  require- 
ments to  be  met  when  maneuvering.  First  among  these 
are  the  peculiar  torque  characteristics  of  the  propeller 
when  making  a  quick  stop  or  reversal  of  the  ship,  at 
which  time  it  may  be  necessary  for  the  propellers  to 
pass  from  full  speed  ahead  to  full  speed  astern  while  the 
ship  itself  is  still  going  ahead.  In  examining  these 
conditions*  and  their  relation  to  the  motor  design  it  be- 

.        *Sec  article  by  Mr.  W.  E.  Thau,  Figs  9  and  10,  p.  249,  this 


comes  apparent  that,  in  order  to  stop  the  propellers  with 
the  ship  making  full  speed  ahead,  the  motors  must  be 
capable  of  delivering  the  full  ahead  torque,  with  a 
proper  margin  of  safety,  when  operating  at  a  slip  of 
approximately  140  percent.  This  requirement  can  be 
m.et  by  inserting  the  proper  amount  of  resistance  in  the 
rotor  circuit  and  a  careful  analysis  was  made  to  deter- 
mine whether  to  put  this  resistance  into  the  rotor  wind- 
ing proper,  which  would  permit  of  a  squirrel-cage  motor 
being  used,  or  to  place  it  external  to  the  rotor,  necessi- 


FK       I  II     1  HE  MMN  PROPELLING  MOTORS  FOR  THE  BATTLESHIP 

Tfiinessce 

tating  a  slip-ring  type  of  motor.  After  making  up  ten- 
tative designs  of  both  types  of  machines  it  developed 
that,  by  employing  a  special  type  of  squirrel-cage  wind- 
ing, a  motor  could  be  built  that  combined  the  requisite 
high  torque  characteristics  during  reversal  with  a  low 
slip  and  high  efficiency  at  full  load.  While  such  a  ma- 
chine would  be  relatively  simple  from  the  standpoint  of 
control,  it  was  found  that  the  heat  generated  in  the  rotor 
windings  during  a  quick  stop  or  reversal  of  the  pro- 
pellers was  of   such  magnitude  that,   to  make  proper 


252 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


provision  for  heat  storage  and  to  take  care  of  the  hnear 
expansion  and  contraction  of  the  rotor  winding  caused 
by  changing  temperatures,  would  necessitate  special 
construction  entirely  beyond  the  limits  of  experience. 
Owing  to  the  importance  of  the  application,  this  was  a 
serious  objection.  On  the  other  hand,  the  slip  ring  type 
of  machine  permitted  this  large  extra  amount  of  heat 
to  be  absorbed  in  the  rheostat,  away  from  the  motor, 
which  naturally  tends  towards  greater  reliability. 
Furthennore,  the  squirrel-cage  motor  showed  a  poorer 
power-factor  under  all  conditions  of  load.     All  in  all, 


3270  volts,  and  at  15  knots  it  is  2125  hp,  36.2  cycles, 
three-phase,  36  poles,  118  r.p.m.,  3250  volts.  There  is 
also  required  a  maximum  capacity  for  each  motor  of 
8375  hp  at  180  r.p.m.  Propeller  speeds  intermediate 
between  and  below  those  given  above  are  secured  by 
controlling  the  speed  and  frequency  of  the  turbine- 
u-enerator,  there  being  a  special  governing  mechanism 
provided  on  the  steam  turbine  for  this  purpose. 

At  speeds  up  to  15  knots,  the  motors  operate  nor- 
m.ally  on  the  36  pole  connection,  the  total  power  being 
supplied  by  one  generator.     Above  15  knots  the  24  pole 


FlC.   2— GENERAL  ASSEMBLY  OF  PROPELLING  MOTORS 


the  preponderance  of  advantages  appeared  to  be  with 
the  slip  ring  tj'pe  of  motor,  which  was  consequently 
adopted. 

EATING 

The  power  specified  for  driving  the  propellers  of 
tlie  Tennessee  at  her  full  speed  and  cruising  speed  was 
28000  shaft  hp,  170  r.p.m.  at  21  knots  and  8500  shaft 
hp,  118  r.p.m.  at  15  knots.  There  are  four  propellers, 
each  driven  by  one  motor,  arranged  for  two  synchron- 
ous speeds.  The  full  rating  of  each  motor  at  21  knots 
is  7000  hp,  34.6  cycles,  three-phase,  24  poles,  170  r.p.m.. 


connection  is  used  on  the  motors  and  still  only  one  gen- 
erator is  required  up  to  and  including  16. i  knots,  above 
which  speed  it  is  necessary  to  use  both  generators.  The 
motors  and  control  are  arranged  so  that  all  starting  and 
reversing  is  normally  performed  with  the  motors  on  the 
24  pole  combination.  A  fortunate  coincidence,  which 
was  taken  advantage  of  in  this  connection,  is  the  fact 
that  as  soon  as  the  power  is  taken  off  the  motors  the 
speed  of  the  propellers  drops  to  about  75  percent  of  the 
previous  speed.  Therefore  assuming  that  it  is  desired 
to  get  under  way  and  to  make  a  certain  speed  on  the  36 


June,  1 92 1 


THE  ELECTRIC  JOURNAL 


253 


pole  connection,  the  motors  are  first  brought  up  to  that 
speed  on  the  24  pole  connection.  Then,  as  the  power  is 
taken  off  the  motors  for  switching  to  the  36  pole  con- 
nection, the  speed  of  the  propellers  drops  to  75  percent 
or  to  a  point  nearly  corresponding  to  the  36  pole  speed. 


FIG.   ,V-     >1A1UK   I  nkl.    l;i.\|i\    K  IK    \\l\niN(J 

The  advantage  of  this  is  that  the  motors  can  be  changed 
from  24  pole  to  36  pole  operation  with  the  steam  turr 
bine  running  at  practically  the  same  speed,  thus  insur- 
ing that  the  motors  and  generators  will  be  brought  into 
step  quickly  and  without  excessive  strain  on  the  wind- 
ings during  the  switching  operation.  As  soon  as  the 
motors  and  generators  have  come  into  step,  they  are 
brought  up  together  to  the  desired  speed. 

To  design  a  motor  of  this  rating  suitable  for  marine 
work  is  a  problem  quite  different  from  ordinary  land 
practice.  The  weight  must  be  kept  to  a  minimum,  the 
available  space  is  restricted  and  these  conditions  must 
be  met  without  in  any  way  handicapping  the  factor  of 
reliability,  the  paramount  requirement  of  this  applica- 
tion. In  order  to  obtain  the  lowest  weight  practicable, 
the  active  material  was  reduced  by  employing  forced 
ventilation,  while  the  mechanical  parts  were  made  light 
it[  weight,  and  yet  of  ample  strength  by  employing  steel 
for  practically  all  the  castings.  With  foundations  of 
the  character  available  on  shipboard  a  bracket  type  of 
motor  was  practically  the  only  choice.  The  bracket 
bearing  construction,  however,  serves  admirably  to  keep 
the  shaft  in  line  and  to  maintain  proper  running  clear- 
ance between  stator  and  rotor,  and  it  goes  far  towards 
obtaining  the  required  strength  and  rigidity  of  the  ma- 
chme  as  a  whole,  combined  with  low  weight  and  mini- 
mum of  space.  In  order  to  gain  full  access  to  all  parts 
of  stator  and  rotor  windings,  the  foundations  for  the 
motor  are  extended  to  permit  sliding  the  stator  forward 
a  distance  sufficient  to  expose  the  rotor  completely.  To 
accomplish  this  it  is  necessary  to  loosen  the  after  bear- 
ing bracket,  to  remove  the  upper  half  of  the  fonvard 


bearing  and  to  support  the  shaft,  for  which  purpose  a 
set  of  lifting  gear  is  provided  in  each  motor  room. 

STATOR 

The  necessary  strength  and  rigidity  required  of  the 
stator  are  obtained  by  using  a  one  piece,  cast  steel  frame 
of  ring  and  web  construction,  with  supporting  feet  ex- 
tending across  the  entire  length  and  cast  integral  with 
the  frame.  A  groove  is  planed  in  the  under  side  of 
each  foot  and  there  is  a  corresponding  key  on  the 
foundation  track  in  the  ship,  the  purpose  of  this  ar- 
rangement being  to  keep  the  stator  parallel  to,  and  clear 
of  the  rotor,  when  sliding  the  stator  forward  in  order 
to  gain  access  to  the  internal  parts  of  the  machine. 
Jack  screws  are  provided  in  the  stator  feet  for  the  pur- 
pose of  raising  the  stator  slightly  so  as  to  introduce 
lubricants  between  the  feet  and  the  foundation  tracks 
l)reparatory  to  sliding. 

The  laminations  are  dovetailed  into  ribs  in  the 
frame  casting  and  are  clamped  between  heavy  end 
plates  with  fingers  for  supporting  the  teeth.  The  slots 
are  of  the  straight  open  type  and  the  coils  of  each  wind- 
ing are  completely  formed  and  insulated  before  being 
placed  in  the  slots. 

In  choosing  a  stator  winding  arrangement  for  the 
purpose  of  obtaining  two  synchronous  speeds,  two 
methods  presented  themselves,  viz.,  to  use  either  a  single 
winding  with  suitable  connections  for  both  24  and  36 
poles  or  else  one  complete  winding  for  each  number  of 
poles.  After  investigation,  including  the  making  of 
many  tentative  designs,  an  arrangement  using  two  inde- 
pendent windings  in  the  stator  was  chosen  as  being  pre- 
ferable to  a  single  winding,  owing  mainly  to  the  com- 
plicated system  of  connections  necessary  with  the  latter 
and  also  due  to  the  fact  that  with  a  single  stator  wind- 
ing, connected  for  both  24  and  36  poles,  it  would  be 
impracticable  to  cut  out  individual  coil';  frn.p  the  stator 


^>>.. 


FIG.  4 — THE  24  POLE  WINDING  DURING  ASSEMBLY 

winding,  which  is  a  generally  accepted  and  quick 
method  of  putting  the  motor  back  in  service  in  case  of 
a  local  breakdown.  Each  slot  contains  two  coil  sides  of 
each  winding,  the  24  pole  coils  being  located  at  the  bot- 
tfm  of  the  slot. 


254 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


In  order  to  withstand  the  adverse  atmospheric  con- 
ditions incident  to  marine  service,  it  is  necessary  that 
the  insulation  of  the  windings  should  be  the  best  ob- 
tainable. This  applies  particularly  to  that  part  of  the 
winding  which  is  imbedded  in  the  core,  the  so-called 
straight  part  of  the  coil,  and  the  solution  of  the  problem 
here  lies  in  the  use  of  mica.  Mica  possesses  an  admi- 
rable combination  of  great  dielectric  strength  and  high 
heat  resistive  qualities,  in  fact  its  insulation  resistance 
increases  with  the  temperature.  It  is  also  resilient  and 
retains  its  resiliency  indefinitely,  thus  helping  to  hold  the 
coils  tightly  in  the  slots.  For  the  purpose  of  applying 
it  on  the  coils,  the  mica  laminae  are  pasted  to  a  very  thin 
paper  to  give  it  the  necessary  mechanical  support  and 
the  mica  on  the  side  opposite  this  paper  binder  is 
covered  with  a  coating  of  shellac.  This  sheet  is  then 
wrapped  around  the  straight  part  of  the  coil,  at  first 


when  completely  assembled  and  connected,  receives  six 
treatments  of  varnish,  the  entire  stator  being  baked  in 
an  oven  after  each  of  these  treatments.  The  coils  are 
held  in  the  slots  by  means  of  bakelite  micarta  wedges 


FIG.  6— A  PORTION  OF  THE  STATOR  COMPLETELY  WOUND  AND 
CONNECTED 

driven  into  grooves  at  the  top  of  the  teeth,  while  the 
coil  ends  are  braced  by  lashing  the  individual  coils  to  an 
insulated  steel  ring,  rigidly  supported  from  the  stator 
frame. 

The  stator  is  provided  with  six  thermocouples, 
three  for  each  winding,  located  in  the  slots  between 
top  and  bottom  coils  for  the  purpose  of  measuring  the 
hot  spot  temperature  of  the  stator  windings. 

In  the  lower  half  of  the  stator  a  series  of  direct- 
current  electric  heaters  are  fitted  for  use  when  the  mo- 
tors are  idle  for  any  con.^^iderable  length  of  time.  The 
purpose  of  these  heaters  is  to  keep  the  temperature  of 
the  motors  slightly  higher  than  that  of  the  surrounding 
air,  thereby  preventing  sweating  or  the   formation  of 


FIG.  5— ALL  OF  THE  24  POLE  WINDING  IN  PLACE 

loosely  by  hand,  whereupon  the  coil  is  placed  on  a  ma- 
chine, which  securely  holds  it  and  has  two  or  more  elec- 
trically heated  plates  which  reVolve  around  the  coil, 
softening  the  shellac  bond  and  exerting  a  uniform  pres- 
sure, thus  slipping  and  tightening  the  wrapper  around 
the  coil  until  the  insulation  takes  on  the  character  of  a 
compact  wall  of  mica. 

The  curved  ends  of  the -coils  projecting  outside  of 
the  core,  where  the  demands  on  the  insulation  are  not  so 
great,  and  where  more  flexibility  is  required,  are  insu- 
lated with  treated  cloth  in  the  form  of  narrow  tape.  To 
guard  against  salt  or  moisture  it  is  essential  that  all 
joints  in  the  insulation  be  effectively  sealed,  which  is 
best  accomplished  by  repeated  varnish  treatments.  Not 
only  are  the  joints  given  several  coats  of  varnish  in- 
dividually as  they  are  made,  but  the  entire  winding, 


FIG    7-SCHEMATIC  WINDING  DIAGRAM  OF  MAIN   MOTOR  ROTOR 

Showing  novel  method  of  connections  by  means  of  which 
the  24  pole  phase  winding  automatically  becomes  a  short-cir- 
cuited winding  for  36  pole  operation. 

condensate  in  the  motor,  which  otherwise  might  occur 
and  possibly  cause  damage  to  the  insulation. 

ROTOR 

The  rotor  must  be  designed  to  transmit  the  torque 
of  the  motor  under  all  conditions  of  load.     Also  it  must 


June,  1921 


THE  ELECTRIC  JOURNAL 


255 


be  capable  of  being  reversed  from  full  speed  and  at  full 
line  voltage,  or  even  in  excess  thereof,  when  required  to 
make  a  quick  stop  or  reversal  of  the  propellers,  and  to 
withstand  the  severe  insulation  and  mechanical  strains 
imposed  by  that  operation.     For  that  reason,  the  rotor 


FIG.  8 — ONE  GROUP  OF  THE  SPECIAL  ROTOR  CONNECTORS 

is  built  up  on  a  strong,  rugged  double-arm  spider,  made 
of  cast  steel  in  one  piece  and  securely  pressed  on  and 
keyed  to  the  shaft.  The  laminations  are  dovetailed  info 
the  spider  and  clamped  between  heavy  end  plates  with 
fingers  for  supporting  the  teeth.  These  end  plates  also 
form  a  support  for  the  projecting  coil  ends.  The 
punchings  have  overhung  slots  with  openings  sufficiently 
large  to  allow  the  assembly  of  coils  completely  formed 
and  insulated  beforehand,  thus  retaining  the  advantages 
of  a  straight  open  slot  construction  without  sacrificing 
the  superior  performance  characteristics  inherent  in  the 
partially  closed  type  of  slot. 

While  the  stator  is  wound  with  two  independent 
windings,  one  for  24  pole  operation  and  one  for  36  pole 
operation,  the  rotor  is  wound  with  only  one  three-phase 
v/inding,  permanently  connected  to  three  collector  rings. 
This  winding  is  adapted  for  either  24  pole  or  36  pole 
operation  by  means  of  a  novel  method  of  connection. 
Referring  to  Fig.  7,  the  view  at  X  represents  a  section 
equal  to  one-sixth  of  one  phase  of  the  rotor  wind- 
ing. The  coils  are  arranged  in  groups  and  by  means 
of  group  connectors  A  are  connected  for  24  poles  in 
two  parallel  circuits,  which  are  joined  in  star  as  indi- 
cated at  V.  Therefore,  with  the  stator  connected  for 
24  poles,  the  machine  will  operate  in  the  usual  manner 
for  induction  motors  having  phase-wound  rotors,  per- 


mitting suitable  external  resistance  for  starting  or  re- 
versing to  be  inserted  in  the  rotor  circuit.  There  being 
two  parallel  circuits,  it  follows  that  certain  points  of  the 
two  circuits  will  have  the  same  potential.  The  groups 
of  coils  are  arranged  in  such  a  manner  as  to  locate  these 
equi-potential  points  at  a  and  a',  b  and  b',  c  and  c'  etc. 
and  these  points  are  joined  together  in  pairs  by  special 
connectors  B.  When  the  motor  is  operated  on  24  poles, 
these  connectors  do  not  carry  any  load  current  since 
they  join  together  points  having  the  same  potential. 

When,  however,  the  36  pole  stator  winding  is 
energized,  the  conditions  change,  as  shown  in  the  view 
at  W,  representing  the  same  section  of  the  rotor  wind- 
ing as  at  X,  so  that  in  the  space  occupied  by  four  poles 
in  the  view  at  X  for  the  24  pole  connection,  the  stator 
winding  when  connected  for  36  poles  will  produce  six 
poles  as  indicated  by  arrows  at  W,  which  indicate  the 
direction  of  the  e.m.f.'s  of  the  several  coils.  The  spe- 
cial connectors  B  now  serve  as  short-circuits,  connect- 
ing pairs  of  coils  together  in  series  with  their  e.m.f.'s 
added.  Such  a  pair  of  coils  is  indicated  by  heavy  lines 
in  the  view  at  W  and  separately  in  the  view  at  Z.  The 
entire  rotor  windings  being  thus  connected  with  all  the 
coils  short-circuited  in  pairs,  the  result  is  that  the  mo- 
tor on  the  36  pole  connection  will  have  characteristics 
similar  to  those  of  a  squirrel-cage  type  of  induction 
motor.  Due  to  the  relatively  large  distance  between 
the  two  coils  in  each  short-circuited  pair,  a  slight  mag- 
netic balancing  action  is  obtained,  similar  to  that  on  a 
squirrel-cage  motor. 

By  this  arrangement  the  motor  has  two  synchron- 
ous speeds  with  but  one  rotor  winding,  the  connections 


FIG.    g — ROTOR   COMPLETELY   WOUND   AND   CONNECTED 

of  which  are  not  changed  in  any  manner  when  going 
from  one  speed  to  the  other.  In  arranging  the  motor 
v.'indings  to  have  the  short-circuited  rotor  characteris- 
tics at  36  poles  and  to  perform  all  starting  and  reversal 
at  24  poles,  the  advantage  is  gained  that  the  propellers 


256 


THE  ELECTRIC  JOURNAL 


Vol.  X\'III,  No.  G 


can  be  brought  from  standstill  up  to  full  power  quickly 
in  either  direction,  without  making  any  change  in  the 
motor  connections. 

The  special  connectors  B  described  above  are  ar- 
ranged symmetrically  in  six  groups  for  the  entire  wind- 
ing and  are  held  down  on  a  supporting  ring  by  means 


FIG.    10 — VIEW  OF  STATOR  AND  ROTOK  LAMIN.\TIONS 

Showing  punched  holes  which  form  the  air  ducts  for  vent- 
ilating the  cores. 

of  brass  plates  and  bolts  in  a  substantial  manner.  A 
close-up  view  of  one  such  group  on  the  finished  rotor 
is  shown  in  Fig.  8  and  a  view  of  the  complete  rotor  is 
shown  in  Fig.  9.  The  rotor  insulation  is  of  the  same 
general  character  as  described  for  the  stator. 

The  shaft  is  made  of  nickel  steel  with  coupling 
flange  forged  integral.  The  shaft  is  hollow,  having  a 
nine  inch  diameter  hole  in  the  center  throughout  the 
length  in  order  to  reduce  the  weight  and  to  peraiit 
thorough  inspection  of  the  material. 

COLLECTOR  AND  BRUSH  RIGGING 

Thetthree  collector  rings  are  made  of  brass  and  arc- 
assembled  on  a  cast  steel  hub  which  is  pressed  on  and 


FIG.    II — MAIN    MOTOR  BEARING   SHELL  AND   DETAILS 
FIG.    12 — INSIDE  VIEW  OF  MAIN  MOTOR  BEARING   HOUSING 

keyed  to  the  shaft.  Each  ring  is  cast  solid,  with  four 
mwardly  projecting  arms  and  bolted  to  the  hub  with 
heavy  bolts.  The  rings  are  well  insulated  from  each 
other  and  from  the  hub  by  bakelite  micarta  washers. 


and  as  an  additional  precaution  the  arms  of  the  rings 
are  covered  with  treated  cloth  tape.  The  whole  is  then 
given  several  dippings  in  black  asphaltum  enamel  and 
baked  in  a  heater  after  each  treatment.  The  brush  rig- 
ging is  assembled  on  a  suitable  casting  and  is  securely 
bolted  to  the  forward  bracket. 

VENTILATION 

The  motor  is  arranged  with  forced  draft  ventila- 
tion under  normal  conditions  of  operation.  Two  ad- 
justable speed  motor-driven  exhaust  fans  are  mounted 
on  top  of  a  sheet  steel  casing,  which  encloses  the  mo- 
tor frame  and  serves  to  confine  the  cooling  air.  In  ad- 
dition the  rotors  themselves  are  provided  with  blowers 
sci  that  the  motors  can  operate  at  full  power  for  short 
periods  of  time  in  case  of  failure  of  the  exhaust  fans, 
from  any    cause.     The  cooling  air  is  taken  from    the 


FIG.   13 — BRUSH   RIGGING   MOUNTED  ON   MAIN    MOTOR  BEARING 
BRACKET 

atmosphere  at  the  main  deck  through  ventilating  trunks 
down  to  the  motor  room,  drawn  into  the  motor  through 
openings  between  the  arms  in  the  bearing  brackets  to 
the  coil  ends,  thence  from  both  sides  through  axial 
ducts  in  the  stator  and  rotor  cores  formed  by  punched 
holes  in  the  laminations.  Fig.  10.  These  axial  ducts 
lead  into  one  radial  duct  located  centrally  in  the  cores. 
This  duct  opens  into  the  chamber  confined  by  the  sheet 
metal  casing  around  the  frame,  whence  the  air  is  drawn 
up  through  the  fans  and  then  up  through  exhaust  trunks 
to  the  deck.  By  this  system  of  axial  ventilation,  the 
cooling  air  is  brought  in  close  contact  with  the  parts  of 
the  machine  where  the  heat  is  generated,  the  heat  is 
conducted  longitudinally  through  the  core  laminations 
and  the  paths  of  the  heat  flow  are  short,  making  this  a 
very  effective  method  of  ventilation. 


June,  1921 


THE  ELECTRIC  JOURNAL 


257 


BEARINGS 

The  motor  bearings  are  designed  to  carry  the 
weight  only  of  the  rotor,  the  end  thrust  from  the  pro- 
pellers being  taken  up  by  separate  thrust  bearings 
located  directly  aft  of  the  motor  rooms.  The  bearings 
are  of  the  spherical  seat,  self -aligning  type  and  are 
made  of  cast  steel,  babbitt  lined,  split  through  the  hori- 
zontal diameter  and  so  designed  that  the  top  half  may 
be  removed  for  examination  of  the  journal  without  dis- 
turbing the  lower  half.  Provision  is  made  for  adjusting 
the  position  of  the  bearings  radially  for  the  purpose  of 
lining  up  and  centering  the  rotor.  The  bearings  are 
c;irried  in  cast  steel  housings,  also  split  through  the 
horizontal  diameter,  and  these  housings  are  secured  to 
heavy  cast  steel  brackets,  made  in  one  piece,  rabbeted 


FIG.   14 — TWO  MAIN  PROPELLING  MOTORS  COUPLED  TOGETHER  FOR 
LOAD  TEST 

One  machine  operating  as  motor  and  driving  the  other 
machine  operated  as  an  induction  generator. 

and  bolted  to  the  stator  frame,  the  whole  making  a  veiy 
rigid  and  substantial  construction. 

Under  ordinary  conditions  of  operation,  lubrication 
of  the  bearings  is  supplied  from  the  ship's  oil  pressui'e 
system.  As  a  reserve  provision,  the  bearings  are  also 
equipped  with  oil  rings  so  that  in  case  of  failure  of  the 
oil  supply  the  bearings  are  designed  to  operate  in- 
definitely at  full  speed  without  overheating.  Each 
housing  is  fitted  with  a  thermometer  and  with  an  il- 
luminated sight  flow  indicator  in  the  oil  drain.  Par- 
ticular care  is  also  taken  by  means  of  oil  guards  to  pre- 
vent oil  from  passing  out  of  the  bearing  housings  into 
'.he  motor. 


The  motors  were  tested  at  the  factory  to  determine 
the  actual  performance  characteristics,  air  delivery  and 
temperature  rise,  and  the  motor  performance  at 
various  speeds,  based  on  these  tests,  is  given  in  Table  I. 

For  a  load  test,  the  shafts  of  two  of  the  motors 
were  rigidly  coupled  together,  as  shown  in  Fig.  14,  one 
to  operate  as  a  motor,  driving  the  other  as  an  induction 
generator.  The  machine  operating  as  a  motor  was 
supplied  with  power  from  a  turbo-alternator,  while  the 
machine  operating  as  an  induction  generator  was  ex- 
cited from  another  turbo-alternator  and  delivered  its 
power  into  the  shop  feeder  system.  By  this  method 
load  tests  were  run  which  closely  approximated  the  full 
power  operation  of  the  motors  and  the  temperatures 
obtained  were  well  within  the  safe  limits  for  the  class 
cf  insulation  employed. 

TABLE  I— MOTOR  PERFORMANCE 


3 

§ 

•/. 

Ph' 

0.  ° 
ex  0 

0  f, 

aT) 
0.  >, 

^0 
> 

2 

fa 

21.8 

1  180 

8375 

24 

36.6 

3460 

04.6 

84 

21 

170 

7000 

24 

34-6 

3270 

94.8 

83-4 

19 

iSi.S 

4625 

24 

30.7 

2900 

94.5 

80 

16.7 

132 

3000 

24 

20.7 

2520 

94-3 

74-5 

15 

118 

2125 

24 

23.8 

2250 

935 

68.6 

15 

118 

2125 

^b 

36-2 

3250 

91.6 

71 

10 

77.8 

1  600 

36 

23.8 

1400 

88.8 

72 

While  making  these  load  tests,  an  interesting  op- 
portunity presented  itself  for  making  a  check  test  on 
the  method  employed  in  computing  the  efficiency  of  the 
motor.  The  efficiencies  in  the  tabulation  above  are 
calculated  on  the  basis  of  the  separate  losses  being  de- 
termined in  the  usual  manner.  When  the  load  tests 
were  made  a  set  of  kilowatt  input-output  readings  were 
taken,  showing  an  over-all  efficiency  of  the  two  ma- 
chines which  checked  to  approximately  one-quarter  of 
one  percent  of  the  efficiency  as  calculated  from  the 
separate  losses.  This  close  agreement  is  gratifying 
since  it  rarely  happens  that  load  tests  can  be  con- 
ducted on  such  large  machines.  Knowing  the  motor 
efficiency  to  within  such  close  limits,  the  power  con- 
sumption of  the  propellers  under  varying  conditions  can 
be  determined  with  ease  and  accuracy,  enabling  a  close 
analysis  to  be  made  of  the  whole  problem  of  ship  pro- 
pulsion. This  of  itself  is  an  important  argument  in 
f-'vnr  rf  electric  drive. 


Tbn  CQjitrol  Room  CitcthI:  T!)('f):\kor  ' 

E.  K.   KEAU 

Supplj'  Engineering  Dept., 

Westinghouse  Electric  &  Mfg.  Company 


((ipniDivt 


THE  circuit  breaker  equipment  on  electrically  pro- 
pelled battleships  must  be  as  reliable  as  tlae  gen- 
erators and  motors  themselves.  Every  detail 
must  therefore  be  carefully  considered,  to  be  sure  that 
nothing  will  fail  and  thus  render  any  propelling  unit 
inoperative.  The  circuit  breakers  are  the  means  by 
which  the  flexibility  of  operation  is  secured  and  this 
advantage  of  the  electric  drive  is  lost  if  the  circuit 
breakers  are  not  at  all  times  in  good  operating  condi- 
tion. 

The  operating  conditions  on  the  Tennessee  are 
widely  different  from  the  usual  commercial  practice 
in  that  the  total  output  of  the  generators  is  used  by  one 
set  of  motors,  the  generators  being  controlled  to  suit 
the  load  on  the  motors.  To  prevent  damage  to  the 
machinery  and  also  to  prevent  improper  operation, 
causing  delays,  the  generator  and  motor  control  equip- 
ment is  interlocked  so  that  improper  operation  is  im- 
possible. 

An  outstanding  feature  of  the  control  is  the  re- 
quirement that  the  governor  of  the  turbine  be  set  for 
slow  speed  before  the  field  of  the  main  generator  can 
be  opened,  and  further  that  the  field  shall  be  opened 
before  the  power  circuits  can  be  opened  or  closed. 
The  opening  of  the  field  contactor  before  operating 
any  of  the  oil  circuit  breakers  reduces  the  current  brok- 
en in  switching  to  a  minimum,  but  the  consideration 
of  absolute  reliability  requires  that  the  oil  circuit 
breakers  be  capable  of  interrupting  the  generator  cur- 
rent under  any  conditions  the  operator  may  impose  on 
them.  The  generators,  however,  are  never  operated 
in  parallel  and  the  circuit  breakers  never  open  auto- 
matically. 

This  reducing  of  the  power  is  required  in  order 
that  the  load  imposed  on  the  generators  by  the  motors, 
when  changing  control  set  ups  during  maneuvering, 
may  not  be  greater  than  should  be  placed  on  the  turbo- 
generators. The  operation  of  the  circuit  breakers 
after  the  power  has  been  reduced  also  reduces  the 
wear  on  the  contacts  from  arcing  and  the  burning  and 
carbonization  of  the  oil. 

The  castings  are  made  of  steel  in  preference 
to  cast  iron,  where  subject  to  any  strains,  because  it 
is  stronger,  resulting  in  a  lower  weight.  The  appara- 
tus must  not  be  subject  to  the  corrosive  effect  of  mois- 
ture laden  salt  air,  which  requires  that  all  parts  must 
be  made  from  nonferrous  material  or  else  protected 
with  a  rust  preventive  coating.  All  large  shafts  are 
made  of  cold  rolled  steel  and  thoroughly  sherardized. 
All   bearings    for    steel    shafts   are   made   with    brass 


liners  and  provided  with  convenient  oil  holes.  All 
small  pins  are  made  from  phosphor  bronze.  All  cot- 
ter pins,  bolts,  nuts  and  washers  are  sherardized. 

CIRCUIT  BREAKERS 

The  circuit  breakers  are  mounted  on  21  inch  cen- 
ters in  a  steel  structure  with  steel  barriers  between  ad- 
jacent breakers.  Removable  ebony  asbestos  doors 
cover  each  end  of  each  cell.     A  working  aisle  of  30 


FIG.     I— AISLE    BETWEEN    ROWS    Of'  CIRCUIT    BREAKERS    WITH    TANK 
LIFTER  IN  USE 

inches  is  provided  between  rows  of  circuit  breakers 
for  use  in  inspection  and  maintenance,  as  shown  in  Fig. 
I. 

The  oil  circuit  breakers  included  in  this  equip- 
ment are  all  single  throw,  and  rated  at  40  cycles,  3500 
volts,  as  follows: — 

Twelve  1600  ampere,  two  pole  circuit  breakers  \vith  three 
pole  disconnecting  devices  for  the  generators  and  for  motor 
reversing. 

Two  800  ampere,  three  pole  circuit  breakers  with  three- 
pole  disconnecting  devices  for  motor  ties. 

Four  1600  ampere,  three  pole  circuit  breakers  for  the  24  pole 
connection. 

Four  800  ampere,  three  pole  circuit  breakers  for  the  36  pole 
conection. 

Four  2000  ampere,  two  pole  circuit  breakers  for  short- 
circuiting  the  motor  secondaries. 


June,  1 92 1 


THE  ELECTRIC  JOURNAL 


259 


The  circuit  breakers  are  made  oil  tight  so  that  the 
rolling  and  pitching  of  the  ship  will  not  spill  the  oil, 
and  are  proportioned  so  that  a  proper  head  of  oil  is 
insured  over  the  contacts  under  all  conditions. 

The  circuit  breaker  used  in  short-circuiting  the 
motor    secondary    is    shown    in    Fig.    2.     This    picture 


FIG.    2 — 2000    AMPERF,   TWO   POLE   CIRCUIT   BREAKER   FOR    SHORT- 
CIRv-.UlTING    MOTOR   SECONDARY 

gives  a  good  view  of  the  substantial  construction  of 
the  circuit  breaker.  All  of  the  castings  are  of  steel  or 
bronze  with  the  exception  of  those  carrying  current 
which  are  copper.  The  wedge  shaped  movmg  contact 
with  the  renewable  arcing  screw  are  clearly  shown. 
Two  sets  of  fingers  are  used  on  this  circuit  breaker  to 
keep  down  the  length  of  the  moving  contact. 

The  circuit  breaker  is  held  closed  by  the  toggle 
of  the  operating  mechanism  being  forced  over  center, 
the  operating  lever  being  latched  in  the  closed  position 
as  double  security.  Thus  any  failure  in  the  connecting 
linkage  or  of  the  lever  latch  will  not  allow  the  circuit 
breaker  to  drop  open. 

Stationary  Contacts — Fig.  3  shows  the  construc- 
tion of  the  stationary  contacts  of  the  circuit  breakers. 
The  insulator  is  of  molded  bakelite  whicli  cannot  be 
fractured  by  shocks  from  gunfire  or  omer  causes. 
The  creepage  distance  over  the  surface  is  somewhat 
greater  than  in  ordinary  commercial  practice  because 
of  the  salt  moisture  conditions.  The  accuracy  of  the 
molding  of  this  material  made  possible  a  clamp,  which 
is  machined  where  it  fits  the  insulator  and  where  it 
bolts  up  against  a  machined  face  on  the  circuit  break- 
er frame,  making  the  lining  up  of  the  contacts  verv 
simple.  The  large  arcing  contact  is  clearly  shown,  to- 
gether with  the  twin  shunts  for  keeping  the  current 
from  the  plunger  guides  during 'the  opening  period  in 
the  operation  of  the  circuit  breakers.  A  strong  com- 
pression spring  is  used  on  the  arcing  contact,  to  insure 
that  it  follows  the  arcing  screw  down  as  the  circuit 
breaker  opens. 

The  forged  copper  fingers  are  carried  on  the  end 


of  a  flexible  copper  leaf  shunt  backed  up  I)y  a  pair 
of  strong  springs  which  insure  an  even  pressure  on 
each  finger.  The  springs  are  under  considerable  initial 
tension  when  the  moving  ci^ntact  first  engages  the  fin- 
gers, so  that  there  is  no  possibility  of  the  contacts 
chattering  during  the  closing  and  opening  operation. 

Finger  contacts  were  adopted  for  this  insulation 
because  the  equipment  must  be  easy  to  operate.  Fing- 
ger  contacts  make  a  circuit  breaker  ea-^ier  to  operate 
than  any  other  type  of  contact  because  the  contact 
pressure  is  lower  and  because  the  vertical  component 
of  the  contact  pressure  is  only  about  a  third  of  the 
normal  pressure.  The  major  portion  of  the  effort 
required  to  operate  a  circuit  breaker  is  used  in  over- 
coming the  sliding  friction  of  the  contacts  which  is 
low  because  the  pressure  is  low.  Finger  contacts  are 
also  desirable  because,  since  they  are  Individually 
small,  uniform  contact  is  obtained  over  the  total  area 
of  the  contact  surface. 

Disconnecting  Device — The  details  of  the  two- 
pole  1600  ampere  circuit  breakers  with  three-pole  dis- 
connecting devices  are  shown,  with  the  disconnecting 
device  closed  and  the  tank  on,  in  Fig.  4,  and  with  the 
disconnecting  device  open  and  the  tank  off  in  Fig.  5. 
The  disconnecting  device  consists  of  a  set  of  contacts 
carried  on  a  rigid  base  supported  in  the  main  steel 
structure.  The  contacts  are  located  on  the  base  with 
a  spacing  that  corresponds  to  the  spacing  of  the  con- 
tacts on  the  circuit  breakers.  They  are  duplicates  of 
the  circuit  breaker  stationary  contacts  with  the  excep- 
tion that  there  are  no  arcing  contacts.  Arcing  contacts 
are  not  needed  because  the  disconnecting  device  is  in- 
terlocked to  prevent  its  being  opened  or  closed  unless 
the  circuit  breaker  is  open.     The  fingers  on  the  bottom 


CIRCUIT  BREAKER  STATIONARY  CONTACTS 


of  the  contacts  engage  wedge  shaped  terminals  on  the 
circuit  breaker  studs  when  the  circuit  breaker  is  pushed 
up  under  it. 

The  circuit  breaker  is  carried  on  a  cradle  which 
slides  up  and  down  on  two  vertical  parallel  rods  which 


26o 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  0 


are  supported  from  the  steel  structure  by  steel  castings. 
The  cradle  is  raised  by  means  of  a  toggle  device  which 
goes  over  center  against  a  stop  in  the  closed  position. 


FIG.  4 — CIRCUIT  HREAKF.R  WITH  TANK  ON  AND  DISCONNECTING 
SWITCH  CLOSED 

This  provides  ease  of  closing,  definite  location  in  the 
closed  position  and  assurance  that  it  will  stay  in  the 
closed  position  in  spite  of  any  shocks.     The  toggle  is 


FIG.    5 — TWO-POI.E   CIRCUIT  BREAKER   WITH   TANK   OFF   AND   DIS- 
CONNECTING SWITCH  OPEN 

restrained,  when  in  the  closed  position,  by  a  wing  nut 
as  an  additional  safe  guard.  Since  the  stationary  con- 
tacts of  the  disconnecting  device  are  directly  over  the 


circuit  breaker  studs,  the  raising  of  the  circuit  breaker 
provides  a  straight  line  path  from  the  bus-bars  down 
through  the  circuit  breaker  and  up  again  to  the  bus- 
bars on  the  other  side.  The  contacts  arc  surrounded 
by  micarta  tubes  to  provide  additional  insulation  be- 
tween studs  in  the  closed  position.  The  hole  in  the 
tube  is  provided  for  ventilation. 

STRUCTURE    ASSEMBLY 

Fig.  6  shows  a  front  view  of  the  structure,  taken 
while  the  apparatus  was  on  the  shop  assembly  floor, 
with  the  ebony  asbestos  doors  ofif,  showing  the  opera- 
ting end  of  the  circuit  breakers.  The  circuit  breaker 
at  the  left  is  shown  open  with  the  removable  handle, 
one  of  which  is  placed  in  each  cell  so  as  to  be  always 
available,  inserted  ready  to  lower  the  circuit  breaker 
out  of  the  disconnecting  device.     The  crescent  shaped 


•rf^ 


«■  m  n 


FIG.  6 — CIRCUIT  BREAKER  STRUCTURE  WITH  DOORS  OFF 

cam  on  the  side  of  the  vertical  operating  bar  prevents 
the  lowering  of  the  circuit  breaker  unless  the  circuit 
breaker  is  first  opened.  The  second  circuit  breaker 
has  been  lowered.  The  curved  guard  on  the  raising 
and  lowering  toggle  lever  has  moved  around  the  cam 
on  the  bar  so  as  to  prevent  the  closing  of  the  circuit 
breaker.  The  steel  plate  extending  down  along  side 
of  the  operating  bar  prevents  the  removal  of  the  pin 
connecting  the  bar  to  the  rod  which  connects  to  the 
operating  lever.  When  the  circuit  breaker  is  open 
the  pin  is^  opposite  the  hole  in  the  guard  and  can  be 
removed.  The  arm  on  the  toggle  lever  prevents  the 
removal  oi  the  tank  unless  the  circuit  breaker  js  low- 
ered so  that  the  disconnecting  device  is  open.  The 
circuit  breaker  on  the  right  does  not  have  a  disconnect- 


June,  1921 


THE  ELECTRIC  JOURNAL 


261 


ing  device  and  is  therefore  mounted  rigidly  in  the  steel 
structure. 

The  confined  space  in  which  the  circuit  breakers 
are  mounted,  together  with  the  rigidity  of  the  tank 
supports  and  the  weight  of  the  tank  when  filled  with 
oil,  requires  a  truck  type  of  tank  lifter.  This  is  shown 
in  use  in  Fig.   i.     A  cradle  which  carries  the  tank  is 


FIG.   7 — MAIN  r,ENER.\TOR  FIELD  CONTROL  EQUIPMENT 

Consisting  of  field  contactor  and  booster  field  rheostat. 

raised  and  lowered  by  means  of  the  long  screw  shown 
in  front.  The  removable  handle  furnisiies  an  easy 
means  for  rotating  this  screw.  One  of  the  three 
wheels  is  shown  at  the  front  just  under  the  screw. 
The  tank  lifter  is  made  sufficiently  strong  that  it  can  be 
used  in  mounting  or  removing  a  complete  circuit  break- 
er. 

FIELD    CONTACTOR 

Since    the    field    contactor    must    open    and    close 
eveiy  time  a  switching  operation  is  made  the  duty  on 


The  ruggedness  of  the  field  contactor  is  evident 
from  Fig.  7.  It  is  built  on  the  lines  of  standard 
starting  contactor  practice,  with  rolling  contacts  which 
provide  a  main  copper  to  copper  circuit,  and  with  the 
final  break  taking  place  between  a  carbon  arcing  con- 
tact and  the  curled  end  of  the  moving  contact.  A 
strong  blowout  coil  and  arc  chute  with  arc  splitters 
is  provided  on  the  upper  or  main  contact.  The  lower 
or  field  discharge  contact  engages  before  the  upper 
contact  is  broken.  The  contactor  is  closed  by  a  spring 
which  is  carried  across  center  by  the  forward  motion 
of  the  operating  lever  and  is  retained  by  a  latch  in 
that  position  while  the  booster  field  rheostat  shown  at 
the  right  is  adjusted  by  the  backward  and  forward  mo- 


FIG.   8 — SHOP  .\SSEMBLV  OF  OPERATING   LEVERS 

tion  of  the  operating  lever.  Moving  the  lever  to  the 
extreme  backward  position  disengages  the  latch  and 
the  operating  spring,  now  on  the  other  side  of  center, 
and  opens  the  contactor  with  a  snap. 

Since  it  was  desired  to  keep  the  equipment  as  sim- 
ple as  possible,  the  field  contactor  was  made  manuall)' 
operated.  The  latching  of  the  contactor  closed  per- 
mitted the  use  of  the  same  operating  lever  for  varying 
the  booster  field  rheostat,  as  shown  at  the  right  in  Fig. 
7.  It  is  connected  to  the  operating  rod  by  a  rack  and 
pinion.  The  latch  on  the  field  operating  lever  has  33 
teeth  which  permits  close  adjustment  of  the  booster 
rheostat  and  prevents  the  adjustment  from  changing 
when  once  set. 


Port  Interlocking  Bar 


Starboard  Interlocking  Bar 


Open 

False  Floor 


FIG.    9 — SCHEMATIC    DIAGRAM    OF   LEVER    INTERLOCKS 


it  is  very  severe.  In  case  the  booster  set  is  not  run- 
ning, the  field  contactor  may  have  to  interrupt  the  full 
field  current  of  the  main  generator.  It  is  capable  of 
opening  the  maximum  field  current  several  thousand 
times  without  requiring  attention  or  renewal  of  the  arc- 
ng  contacts. 


OPETIATING  LEVERS 

The  operating  levers  for  control  of  the  propulsion 
machinery  are  grouped  together  as  shown  in  Fig.  8. 
This  places  the  entire  operation  immediately  under  the 
observation  of  the  officer  on  watch  in  the  control  room. 
This  compactness  makes  the  interlocking  more  simple 


362 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


and  positive,  because  the  interlocking  members  can  be 
made  short  and  rigid. 

The  operating  levers  are  of  the  type  commonly 
used  in  railway  signal  interlocking  plants.  The  han- 
dles are  at  a  convenient  height  above  the  false  floor, 
with  the  operating  rods,  shafts  and  bell  cranks  on  the 
deck  below  the  floor.  The  effort  required  to  move  the 
lever  from  one  position  to  the  other  is  well  within  the 
strength  of  the  average  man,  using  one  hand.  The 
handle  travels  a  distance  of  26  inches,  the  lever  arms 
being  in  the  ratio  of  4  to  i.  The  levers  are  provided 
with  latches  to  hold  them  in  their  extreme  positions. 
Failure  of  this,  latch  does  not  permit  the  circuit  break- 


Fin.   10 — PORT  OPERATING  LEVER  INTERLOCKS 

ers  to  move,  as  previously  explained.  The  levers  and 
interlocks  are  made  strong  enough  to  withstand  the 
maximum  efforts  of  the  operator  if  he  attempts  an  im- 
proper operation. 

A  verj'  complete  set  of  interlocks  is  provided,  as 
shown  schematically  in  Fig.  9  there  being  two  tiers,  one 
of  the  shuttle  pin  type  below  the  fulcrum,  and  the  other 
consisting  of  hook  and  stub  interlocks  above  the  ful- 
crum. Fig.  10  is  a  view  looking  down  on  tlie  upper 
row  of  interlocks  on  the  port  side.  The  hydraulic 
governor  control  valve  is  shown  at  the  right.  The  hook 
interlocks,  which  prevent  the  opening  or  closing  of  a 
lever  when  the  field  contactor  is  closed,  are  clearly 
shown.  The  second  lever  from  the  right  is  the  tie 
breaker  lever  with  a  pair  of  hooks,  one  connected  to 
each  of  the  two  interlock  bars. 

The  following  interlocks  are  provided : — 


a— The  field  contactor  is  prevented  from  opening,  un- 
less the  steam  wheel  has  been  placed  at  the  slow  speed  set- 
ting, by  a  piston  in  a  cylinder  connected  to  the  hydraulic 
control  of  the  governor.  Raising  of  the  piston  pushes  a  dog 
into  the  path  of  the  lever  and  prevents  the  final  movement 
necessary  to  disengage  the  field  contactor  latch.  This  lock, 
in  connection  with  (d),  insures  that  the  motors  will  not  be 
reversed  at  high  turbine  speed,  with  an  excessive  power 
demand  from  the  system. 

b — The  field  contactor  lever  cannot  be  closed  unless  the 
liquid  rheostat  valve  lever  and  the  motor  secondary  short- 
circuiting  breakers  are  in  the  open  position,  clear  of  the 
stubbing  interlock,  allowing  the  interlock  bar  to  move  trans- 
versely and  move  the  interlock  at  the  left  of  the  field  lever 
out  from  in  front  of  the  field  lever.  This  prevents  energizing 
a  motor  unless  maximum  resistance  is  inserted  in  the  motor 
secondary. 

c — A  pivoted  cam  on  the  tie  breaker  lever  prevents  the 
closing  of  the  tie  breaker  lever  if  both  generator  breaker 
levers  are  closed,  or  of  one  generator  breaker  lever  if  the 
other  generator  breaker  lever  and  the  tie  breaker  lever  are 
closed.  This  cam  engages  the  shuttle  interlock  bars  in  the 
lower  tier  between  the  generator  levers  and  the  tie  breaker 
lever.  This  prevents  paralleling  the  generators. 

d — The  closing  of  the  field  contactor  lever  drives  the 
interlock  bar  transversely  and  causes  the  hook  interlocks 
to  prevent  movement  of  any  of  the  levers  except  those  con- 
trolling the  rheostat  valves  and  motor  secondary  short- 
circuiting  breakers.  The  interlock  bar  is  prevented  from 
moving  from  the  locking  position,  while  the  booster  field 
rheostat  is  being  adjusted,  by  a  dog  not  shown  in  Fig.  9, 
which  is  disengaged  by  the  last  movement  of  the  lever' that 
also  trips  the  field  contactor.  This  prevents  operating  the 
circuit  breakers,  except  when  the  generators  arc  de-ener- 
gized. This  not  only  accomplishes  the  purpose  given  under 
(a),  but  also  reduces  the  wear  of  the  arcing  tips  and  the 
rate  of  carbonization  of  the  oil,  as  the  currents  have  fallen 
to  low  values  before  the  breakers  are  opened. 

t'— The  movement  of  the  interlock  bar  by  the  field  lever 
moves  the  stubbing  interlocks  from  in  front  of  the  rheostat 
valve  and  motor  secondary  levers  so  they  can  be  closed, 
except  as  covered  in  {g).  There  is  no  restriction  upon  the 
opening  of  the  two  levers  last  mentioned. 

/—The  closing  of  the  tie  breaker  lever  mechanically 
connects  the  port  and  starboard  interlock  bars  by  connecting 
together  the  two  hook  interlocks,  each  of  which  is  connected 
to  a  different  bar.  This  is  clearly  shown  in  Figs.  g.  and  10. 
This  provides  for  locking  the  breaker  levers  of  all  four 
motors  by  means  of  either  generator  field  lever,  when  the 
motors  are  operating  from  one  generator. 

g — The  lever  controlling  the  motor  short-circuiting 
breakers  is  prevented  from  closing  until  after  the  lever 
controlling  the  rheostat  valves  has  been  closed,  which  pushes 
the  square  ended  lower  interlock  out  of  its  path.  This  pre- 
vents short-circuiting  the  motors,  without  first  allowing 
the  rheostat  liquid  level  to  be  raised.  The  breaker  lever  is 
not  closed  until  after  the  liquid  reaches  its  maximum  level 
as  observed  from  the  gauge  glass  on  the  liquid  rheostat. 

/i— The  following  pairs  of  levers  are  prevented  from 
being  in  the  closed  position  at  the  same  time  by  straight 
pin  type  interlocks  in  the  lower  tier. 

Ahead  Back 

24  Pole 36  Pole 

36  pole Back 

The  36  pole  connection  is  for  economical  cruising  pur- 
poses only  and  there  is  no  necessity  for  backing  on  this  con- 
nection. 

i_The  ahead  lever  is  prevented  from  closing  until  after 
the  24  pole  lever  has  been  thrown,  by  a  square  end  pin  inter- 
lock in  the  lower  tier,  which  is  moved  out  of  the  way  by  the 
closing  of  the  24  pole  lever.  This  lock  is  a  reminder  that 
the  motors  must  be  started  on  the  24  pole  connection. 

/—A  circuit  breaker  cannot  be  lowered  out  of  the  dis- 
connecting devices  unless  the  circuit  breaker  is  open.  The 
circuit  breaker  cannot  be  disconnected  from  the  operating 
rod  unless  it  is  open.  If  the  circuit  breaker  is  lowered,  the 
operating  lever  cannot  be  moved  unless  disconnected  from 
the  circuit  breaker.  The  circuit  breaker  tank  cannot  be  re- 
moved unless  the  circuit  breaker  is  lowered  out  of  the  dis- 
connecting device. 


Lilg 


M.  CORNELIUS 

Switchboard  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


APPARATUS  for  battleship  service  must  be 
rugged  and  extremely  reliable.  In  addition  to 
withstanding  ordinary  shipboard  conditions,  it 
must  be  unaflfected  by  severe  shocks  such  as  the  ship 
may  experience  from  her  own  gunfire  or  from  external 
sources.  The  insulators  for  the  high  voltage  appara- 
tus are  therefore  made  of  molded  bakelite  or  of  pressed 
micarta  tubes.  Ebony  asbestos  wood  is  used  for 
switchboard  panels  and  controllers.  Cast  grid  resis- 
tors are  not  permitted  except  where  they  are  very 
heavy,  and  light  grids  are  of  expanded  alloy  sheet.s. 
Alloy  ribbon  is  also  used  for  resistors.  Wire  resistoi"s 
are  wound  on  steel  tubes  insulated  with  sheet  asbestos. 
The  circuit  breakers  are  equipped  with  shockproof 
latches  and  overload  trips  have  time  element  dash  pots 
as  an  "extra  precaution  against  accidental  tripping. 

The  possible  deflection  of  decks  and  bulkheads 
must  be  considered  in  designing  structures.  A  struc- 
ture having  uprights  extending  to  an  upper  deck  is  not 
braced  rigidly  and  if  clips  are  used  they  are  slotted 
for  the  bolts  so  that  a  deck  deflection  would  not  cause 
the  uprights  to  buckle.  Structures  are  located  at  least 
six  inches  away  from  bulkheads  for  the  same  reason. 

Mechanical  interlocks  are  installed  where  mistakes 
in  operation  would  damage  machinery  or  cause  person- 
al injury.  These  interlocks  also  prevent  delays  in  op- 
eration by  insuring  that  the  correct  sequence  is  fol- 
lowed. Electrical  interlocks  are  used  only  where  me- 
chanical interlocks  are  not  feasible,  or  where  the  two 
pieces  of  apparatus  to  be  interlocked  are  widely  sep- 
arated. 

Apparatus  in  the  engine  rooms  or  cables  passing 
through  them  must  be  capable  of  operating  in  room 
temperatures  which  average  no  derees  F.  The  control 
room  and  motor  rooms  are  comparatively  cool,  the 
latter  especially  so  because  of  the  large  volume  of  out- 
side air  supplied  to  the  propelling  motors. 

THE  CONTROL  ROOM 

The  control  equipment  for  the  main  turbogenera- 
tors and  for  the  propelling  motors  is  located  in  a  con- 
trol room  separated  from  the  machinery  rooms  by  wa- 
tertight bulkheads.  The  switchboards  for  the  direct- 
current  generators  are  located  in  the  engine  rooms  and 
the  controllers  for  the  motor  driven  pumps  and  blowers 
are  located  close  to  their  respective  motors. 

The  control  room  equipment  consists  of  the  fol- 
lowing apparatus : — 

a — Contactors  with  discharge  resistors  and  booster  field 
rheostats  for  controlling  the  excitation  of  the  alternating- 
current  generators. 


b — Oil  circuit  breakers  for  the  generator  and  motor 
circuits.  These  provide  for  operating  the  four  motors  from 
one  or  two  generators,  for  reversing  the  direction  of  motor 
rotation,  for  operating  the  motors  on  their  low-speed  or  high 
speed  pole  connections  and  for  short-circuiting  the  motor- 
secondary  leads. 

c — Liquid  rheostats  for  starting  the  propelling  motors, 
together  with  controllers  for  the  electrolyte  circulating  pump 
motors. 

(f — Operating  levers  for  the  field  contactors,  oil  circuit 
breakers  and  liquid  rheostat  valves. 

e — Main  turbine  control  equipment,  consisting  of  hy- 
draulic control  valves  for  regulating  speed,  controllers  for 
the  motor  driven  power  limiting  devices  and  emergency  pulls 
for  the  throttles. 

/ — An  instrument  board,  supported  from  the  circuit 
breaker  structure,  containing  gages,  electrical  instruments, 
lamp  indicators,  rudder  indicator,  shaft  revolution  counter, 
turbine  and  shaft  speed  indicators,  machine  temperature 
indicators  and  various  direct-current  power  switches. 

0— Communication  equipment,  consisting  of  voice  tubes, 
telegraphs,  telephones,  gongs,  telautograph,  revolution  in- 
dicators, etc.  for  receiving  and  transmitting  orders. 

/, — A  gage  and  instrument  board  containing  fuel  oil, 
feed  water  and  steam  gages,  oil  burner  control  telegraphs, 
oil  pressure  indicators,  smoke  indicators,  etc.,  at  the  water 
tender's  station. 

The  propelling  machinery  is  in  no  wsv  controlled 
from  the  bridge,  but  all  operations  necessary  to  the 
starting,  stopping,  reversing  and  speed  control  of  the 
propellers  are  done  in  the  control  room  on  orders  re- 
ceived over  engine-order  telegraphs  and  by  telephone 
from  the  bridge.  Operation  is  in  charge  of  an  officer 
stationed  in  the  control  room.  The  fire  rooms,  engine 
rooms,  motor  rooms  and  shaft  alleys  receive  their  or- 
ders from  the  control  room. 

THE  DIRECT-CURRENT   POWER   SYSTEM 

The  connections  of  the  principal  alternating  and 
direct-current  circuits  are  shown  in  Fig.  i.  Each  en- 
gine room  switchboard  controls  three  300  kw  120  /2/10 
volt,  three-wire  direct-current  generators,  a  35  hp 
booster  set  for  the  alternating-current  generator  field 
voltage  variation,  feeders  to  the  motor  controllers  in 
the  pump  room,  excitation  and  auxiliary  power  feeders 
to  the  control  room,  a  feeder  to  the  opposite  engine 
room,  and  feeders  to  the  corresponding  distribution 
board.  Each  switchboard  has  a  set  of  three-wire 
light  and  power  bus-bars  and  two  sets  of  two-wire  pro- 
pulsion auxiliary  bus-bars.  Fig.  2  shows  the  switch- 
board in  the  after  engine  room. 

The  light  and  power  bus-bars  of  the  engine-room 
boards  connect  directly  through  knife  switches  and  ca- 
bles to  the  corresponding  distribution  board.  All  rf 
the  ship's  light  and  power  circuits  are  controlled  from 
these  two  distribution  boards.  These  boards  are  in- 
terconnected so  that  any  part  of  the  ship  can  be  sup- 
plied by  power  from  either  engine  room,  although  the 
two  engine  rooms  cannot  be  operated  in  parallel. 


264 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


Three-wire  direct-current  power  can  be  sup- 
plied to  the  ship,  when  docked,  from  a  shore  system, 
through  tei-minal  boxes  on  deck  and  thence  through 
cables  to  a  generator  panel  of  the  after  engine  room 
board.  The  switches  on  this  panel  are  double  throw, 
the  upper  throw  connecting  the  light  and  power  bus- 
bars and  the  main  auxililiarj-  bus-bars  to  the  generator 
and  the  low^er  throw  connecting  them  to  shore  power. 
Shore  power  can  thus  be  distributed  to  any  part  of  the 
ship. 

One  of  the  three  300  kw  turbogenerators  in  each 
engine   room — the  non-condensing  unit — is   considered 

« u  -  -  :-'■  r..j..  •.  "■  ill  yj, .'  = .-.-.  .=..*-. »  '• 


£<^,  l|{]r 0  0® I444. 

^       -l-rt-     Q  gj  0_p* 


FIG.   I — THE  PRINCIP.^L  .\LTERN.\TING  AND  DIRECT-CURRENT  CIRCUITS 

as  belonging  to  the  propelling  equipment  and  the  other 
two  are  considered  as  belonging  to  the  ship's  light  and 
power  plant.  However,  all  three  units  can  be  used  inter- 
chansjeably  for  either  service. 


The  generators  are  protected  by  two  two-pole  cir- 
cuit breakers  having  a  common  tripping  mechanism. 
The  two  equalizer  poles  are  of  approximately  one-half 
the  current  capacity  of  the  two  main  poles.  Each  equal- 
izer and  main  pole  has  an  overload  time  limit  trip  and 
in  addition,  one  main  pole  has  a  shunt  trip  and  the  oth- 
main  pole,  a  reverse  current  trip.  Each  main  pole  has 
an  extra  stud  between  the  overload  coil  and  the  brush 
for  the  connections  to  the  bus-bars  which  supply  the 
240  volt  propulsion  auxiliarj'  load.  This  load,  which 
includes  the  main  generator  field  excitation,  passes 
through  the  overload  coils  but  is  not  interrupted  when 
the  circuit  breaker  opens. 

The  upper  studs  of  the  main  poles  of  the 
circuit  breakers  connect  through  a  switch  to 
the  ship's  light  and  power  bus-bars,  which 
in  turn  connect  to  the  distribution  boards. 
The  generators  are  paralleled  by  closing  the 
equalizer  poles  of  the  circuit  breaker,  no 
switches  being  provided  in  the  equalizer  cir- 
cuits. A  mechanical  interlock  is  provided  on 
the  circuit  breaker  between  the  closing  arm  of 
the  equalizer  poles  and  that  of  the  main  poles, 
a„^.~,         T-,-,      , .  ,....,^  ,  ,  SO  that  the  equalizer  poles  must  be  closed  first. 

•       ^-^H^i  ,1  j  -  T  ■^t    tL/il'a    '  .*.  Two  knife  switches  are  provided  on  each 

■■■■'■'    —    -CM^^.  generator  panel    for   connectmg   the   generator 

-^raicBiu,  to  the  three-wire  light  and  power  bus-bars  and 
•i-o^.a^.i,  to    the  two-wire    main  auxiliary    bus-bars.     A 
generator  can  thus  supply  both  sets  of  bus-bars 
simultaneously,  if  desired. 

.\11  three  generators  can  be  paralleled  on 
the  light  and  power  bus-bars.  They  can  also 
be  paralleled  on  the  main  auxiliary  bus-bars 
by  disengaging  mechanical  interlocks  between 
the  switches  connected  to  these  bus-bars. 
These  interlocks  are  self  re-setting  after  a 
switch  has  been  opened  and  are  installed  as  a 
reminder  that  two  generators  are  not  to  oper- 
ifiX'Z^  ate  in  parallel  on  the  auxiliary-  bus-bars  except 
H^iSf^n  for  the  time  required  to  transfer  the  load  from 
one  generator  to  the  other. 

The  second  set  of  two-wire  bus-bars  pro- 
vided on  the  engine  room  switchboard  is  en- 
ergized at  all  times  as  a  reserve  source  of  sup- 
ply for  the  propulsion  auxiliary  load,  and  has 
a   separate  voltmeter.     These  bus-bars   can  be 


CONTROL    OF    THE    DIRECT-CUKRENT    TURBOGENERATORS 

The  overspeed  mechanism  of  the  turbine  is 
equipped  witli  an  auxiliary  switch  which  is  connected 
in  the  shunt  trip  circuit  of  the  generator  breaker,  so 
that  the  circuit  breaker  opens  automatically  when  the 
throttle  has  been  tripped,  either  due  to  overspeed  or 
by  hand  through  the  wire  pull  located  at  the  switch- 
board. 


connected  to  two  sources  of  supply  by  means  of 
double-throw  switch.  When  the  ship  is  cruising, 
one  engine  room  will  normally  be  shut  down  and  the 
switch  will  be  thrown  to  the  light  and  power  bus- 
bars of  the  active  engine  room.  When  the  second 
engine  room  is  standing  by  ready  for  service,  or  if  the 
ship  is  steaming  at  high  speed  with  both  engine  rooms 
in  operation,  the  switch  will  be  thrown  to  the  main 
auxiliar}-  bus  feeder  from  the  othi-r  engine  room. 

Each  main  auxiliary  bus  feeder  to  the  opposite 
engine  room  has  an  ammeter  and  an  overload  time 
limit  circuit  breaker  to  clear  the  line  automatically  m 


June,  1921 


THE  ELECTRIC  JOURNAL 


265 


case  of  trouble  in  the  opposite  engine  room.  The  sup- 
ply from  the  reserve  auxiliary  bus  is  therefore  subject 
to  automatic  interruption. 

Each  generator  has  a  voltmeter,  two  ammeters 
connected  to  ammeter  shunts  located  in  the  armature 
leads  at  the  generator  and  a  three-wire  watthour  meter 
connected  to  shunts  located  behind  the  switchboard. 

The  field  rheostat  is  supported  from  the  renr 
framework  of  the  switchboard  and  is  operated  by 
shafts  and  bevel  gears  from  a  hand  wheel  on  the  front 
of  the  board.  The  rheostat  has  a  large  number  of  re- 
sistance steps  and  a  wide  range  of  voltage  can  be  ob- 
tained in  case  it  is  necessary  to  shut  down  the  booster 
set  and  excite  the  alternating- 
current  generator  field  directl}' 
from  one  of  the  300  kw  genera- 
tors. 

FEEDERS     TO     THE     MOTOR     DRIX^EN 
PROPULSION     AUXILIARIES 

Double-throw  knife  switch- 
es are  provided  on  the  engine 
room  boards  for  connecting  the 
feeders  for  the  propulsion  aux- 
iliaries to  either  of  the  two  sets 
of  auxiliary  bus-bars.  All  of 
these  switches  except  the  switch 
for  the  alternating-current  gen- 
erator field  excitation  are  capa- 
ble of  being  thrown  from  one 
bus  to  the  other  under  load,  so 
that  the  auxiliaries  will  not  be 
shut  down  if  the  emergency  re- 
quires that  the  transfer  be  made. 
The  larger  switches  have  special 
blades  and  auxiliary  breaks  to 
reduce  the  time  of  throwing  over 
and  to  assist  in  breaking  the  circuit. 

There  are  six  feeders  on  each  board  for  the  mo- 
tors which  drive  pumps  for  the  condensers  and  for 
the  forced  lubrication  system.  The  feeder  to  the  con- 
trol room  is  fused,  and  a  red  lamp  is  used  to  give  -i 
prominent  indication  of  the  condition  of  the  fuses. 
Each  of  the  above  feeders  have  ammeters  in  circuit. 
Five  switches  are  installed  for  engine  room  ventila- 
ting motors  and  one  for  an  oil  purifier  motor. 

Each  motor  driven  auxiliary  has  its  controller 
mounted  within  easy  reach  of  the  motor.  All  control- 
lers are  manually  operated  and  have  overload  and  no 
voltage  protection. 

CONTROL  OF  THE  BOOSTER   SET 

The  engine  room  switchboard  contains  the  neces- 
sary control  equipment  for  the  booster  motor-genera- 
tor set  which  is  used  for  varying  the  voltage  across 
the  main  generator  field.  No  alternating-current  gen- 
erator field  rheostat  is  used,  and  the  booster  set  adds 
to  or  subtracts  from  the  auxiliary  bus  voltage  of  240 
according  to  the  excitation  demands. 


A  double-throw  switch  is  provided  for  connecting 
the  alternating-current  generator  field  circuit  and  the 
booster  set  circuit  to  either  set  of  auxiliary  bus-bars. 
The  switch  has  a  solenoid  operated  latch  on  each 
throw,  which  prevents  opening  the  switch  unless  the 
alternating-current  generator  field  circuit  is  open  at 
the  field  contactor  in  the  control  room. 

The  booster  set  runs  at  constant  speed,  and  its 
motor  takes  power  from  the  busses  when  the  set  i.' 
boosting  and  returns  power  to  the  busses  when  the  set 
is  bucking.  The  voltage  of  the  booster  generator  is 
varied  in  either  direction  from  zero  by  means  of  a  re- 
versing   field    rheostat    located    in    the    control    room. 


THE   DIRECT-CURREK  1    SU'IH 


IN    THE   AFTER   ENGINE    ROOM 


The  rheostat  has  a  single  resistance  connected  across 
the  240  volt  auxiliary  bus  and  the  various  resistance 
taps  are  connected  in  a  special  manner  to  two  face 
plates.  The  voltage  across  the  booster  generator  field 
is  practically  zero  when  the  face  plate  arms  are  verti- 
cally downward.  When  they  move  in  one  direction 
from  this  neutral  point,  voltage  of  one  polarity  !s 
gradually  increased  across  the  booster  generator  field 
and  when  they  move  in  the  opposite  direction  from 
neutral,  the  field  voltage  is  gradually  increased  in  the 
opposite  direction. 

The  booster  motor  is  protected  by  a  two-pole  cir- 
cuit breaker  having  overload  time  limit  and  no-voltage 
trip.  The  opening  of  this  breaker  also  opens  the  cir- 
cuit to  the  booster  field  rheostat,  thus  de-energizing 
the  booster  generator  field.  The  motor  is  started  hv 
means  of  a  single-pole,  four-point  starting  knife  switch 
and  a  re^stance.  The  booster  generator  circuit  is  al- 
ways open  until  after  the  booster  set  has  been  started. 

A  two-pole  double-throw  transfer  switch,  which 
does  not  open  the  circuit  during  transfer,  is  provided 


266 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


for  disconnecting  the  booster  generator  or  for  placing 
it  into  service  without  the  necessity  of  interrupting  the 
main  generator  field  circuit.  The  switch  has  an 
auxiliary  pole  which  opens  the  circuit  to  the  booster 
field  rheostat,  so  that  the  booster  generator  cjfnnot  be 
short-circuited  with  its  field  energized  in  case  tlie 
switch  is  thrown  before  tripping  the  motor  circuit 
breaker.  A  field  voltmeter  and  field  ammeter  for  the 
alternating-current  generator  and  a  double  reading  am- 
meter for  the  booster  motor  are  installed  on  each  en- 
gine room  board. 

DISCONNECTING   A    BOOSTER    SET    WITHOUT    INTERRUPT- 
ING  THE   ALTERNATING-CURRENT    GENERATOR 
FIELD  CIRCUIT 

If  trouble  develops  in  the  booster  equipment  and 
it  becomes  necessary  to  excite  the  main  generator  di- 
rectly from  one  of  the  300  kw  generators,  tlie  follow- 
ing operations  are  necessary : — 

a — Trip  the  booster  motor  circuit  breaker.  The  main 
generator  field  voltage  becomes  240  after  the  set  has  stopped 
h — Pull  the  motor  starting  switch. 

c — Throw  the  booster  generator  switch  up,  thus  dis- 
connecting the  generator. 

d — Throw  the  auxiliary  motor  and  control  room  feeder 
switches  to  the  reserve  auxihary  bus  one  by  one,  until  only 
the  main  generator  field  circuit  remains  on  the  main  auxi- 
liary bus. 

e — Vary  the  main  auxiliary  bus  voltage  by  means  of  the 
300  kw.  generator  field  rheostat,  as  may  be  required  by  the 
control  room. 

Both  booster  sets  could  be  inoperative  and  the 
ship  could  still  steam  at  lull  speed,  using  one  300  kw 
generator  in  each  engine  room  as  exciters  for  their  re- 
spective main  generators.  Both  alternating-current  gen- 
erators can  be  excited  from  one  300  kw  generator  if  the 
emergency  should  require  it.  In  this  case  excitation 
for  the  main  generators  is  taken  from  the  main  auxili- 
ary bus  of  the  room  which  furnishes  the  exciter  and 
from  the  reserve  auxiliary  bus,  through  the  tie  line,  of 
the  opposite  engine  room.  A  temporar>'  interruption 
of  the  driving  power  is  required  to  set  up  the  exciting 
circuits  according  to  this  latter  scheme. 

OTHER  FEATURES  ON  THE  ENGINE  ROOM   BOARDS 

Each  board  has  a  calibrating  voltmeter  which  can 
be  connected  in  parallel  with  tlie  generator  and  bus 
voltmeters  by  means  of  a  multicircuit  switch.  The  op- 
erator can  compare  the  voltages  of  the  running  and  in- 
coming machines  on  this  voltmeter  when  paralleling 
generators.  Each  board  also  has  a  double  reading 
ground  detector  voltmeter  with  a  multi-circuit  switch 
so  that  any  bus  can  be  connected  to  ground  through 
the  meter.  The  voltage  of  the  booster  generator  can 
also  be  read  on  this  meter. 

All  ammeter  and  watthour  meter  shunts  have  re- 
movable strips  in  series  with  them  to  facilitate  insert- 
ing a  portable  shunt  for  testing  purposes.  Totalizing 
ammeters  are  installed  in  each  main  and  reserve 
auxiliary  bus. 

DIRECT-CURRENT  CIRCUITS  IN   THE  CONTROL  ROOM 

The  control  room  feeders  from  the  240  volt  aux- 
iliary bus-bars    in  each  engine    room  come    to    switch 


panels  forming  a  part  of  the  main  instrument  board  in 
the  control  room.  Eleven  two-pole,  double-throw 
switches  are  installed  for  distributing  power  from 
either  engine  room  to  the  controllers  for  the  motor 
room  blowers,  for  the  liquid  rheostat  pump  motors 
and  for  the  oil  drainage  pump  motors.  Two  feeders 
lead  into  each  motor  room  for  the  blower  motors  and 
heaters  so  that  either  blower  can  be  stopped  from  the 
control  room  if  desired,  by  pulling  the  feeder  switch. 
A  red  lamp  located  at  each  switch  is  connected  across 
the  armature  of  the  blower  motor  to  indicate  when  the 
motor  is  in  operation. 

Two  panels,  one  on  each  liquid  rheostat,  provide 
control  for  the  electrolyte  circulating  pump  motors 
and  have  switches  and  fuses  for  the  control  circuits 
to  the  turbine  governor  control  valve  vibrating  motors 
and  to  the  motors  on  the  turbine  power  limiting  devices. 
Each  pump  motor  has  two  single-pole  overload  time 
limit  circuit  breakers  with  a  common  trip  which  also 
serve  as  a  line  switch.  Two  contactors  which  shunt 
a  three-point  resistor  are  provided  for  the  automatic 
starting  and  no-voltage  protection  of  the  motors. 

There  are  three  sets  of  oil  drainage  pumps  and 
motors  under  the  control  room,  only  two  of  which  are 
connected  in  at  any  one  time.  The  other  set  is  held 
as  a  reserve  in  case  of  tlie  failure  of  one  pump.  The 
control  room  board  has  a  two-pole,  single-throw  switch 
and  a  red  light  for  each  motor  and  in  addition  a  dou- 
ble-throw switch  for  transferring  the  control  circuits 
from  the  two  tank  float  switches  to  the  two  motors  and 
pumps  selected  for  operation.  The  red  light  is  con- 
nected across  the  motor  armature  to  show  when  the 
motor  is  operating.  The  motor  controllers  are  of  the 
automatic  contactor  type. 

BLOWER   MOTOR   CONTROLLERS   IN    MOTOR   ROOMS 

A  two-panel  board  is  located  near  the  two  blowers 
on  each  main  motor  for  controlling  the  adjustably  speed 
blower  motors  and  the  main  motor  heaters.  Each  mo- 
tor has  two  single-pole  overload  time  limit  circuit 
breakers  having  a  common  trip  and  a  sliding  arm  start- 
ing and  field  regulating  rheostat.  A  two-pole,  single- 
throw  fused  switch  on  one  panel  controls  the  heater 
circuit  of  the  propelling  motor.  Two  bulkhead  tj'p'; 
lamps  attached  to  the  main  motor  and  connected  across 
the  armatures  of  the  blower  motors  indicate  to  a  man 
on  the  lower  grating  of  the  motor  room  when  the  blow- 
er motors  are  in  operation. 

MAIN   GENERATOR  FIELD  CONTROL  EQUIPMENT 

The  field  circuits  of  the  alternating-current  gener- 
ator and  of  the  booster  generator  are  looped  into  the 
control  room  in  order  to  provide  manual  operation  of 
the  field  contactor  and  booster  rheostat.  The  field 
contactor  and  booster  rheostat  are  operated  in  common 
from  one  lever,  the  contactor  closing  on  maximum 
field  voltage  at  the  extreme  forward  end  of  the  lever 
travel  and  opening  on  minimum  field  voltage  at  the 
other  extreme  of  the  lever  travel.  This  method  of  op- 
eration causes  the  field  current  to  build  up  quickly. 


June,  1921 


THE  ELECTRIC  JOURNAL 


267 


The  booster  operates  at  maximum  buck  with  the 
field  contactor  open.  In  closing  the  operating  lever, 
the  booster  generator  voltage  changes  from  maximum 
buck  through  zero  and  to  maximum  boost,  and  the  field 
contactor  is  closed  just  before  the  lever  reaches  the  ex- 
treme forward  end  of  its  travel.  The  lever  is  then 
immediately  brought  back  to  the  desired  voltage  posi- 
tion. The  field  contactor  does  not  open  until  just  be- 
fore the  lever  reaches  the  off  position,  when  the  boost- 
er is  again  running  at  maximum  buck. 

The  upper  and  lower  contacts  of  the  field  contac- 
tor are  temporarily  bridged  during  the  operation  of  op- 
ening or  closing.  The  field  discharge  resistor  is  thus 
shunted  across  the  field  before  the  exciting  circuit  is 
opened,  and  is  of  low  enough  resistance  to  limit  to  a 
safe  value  the  voltage  induced  upon  the  collapse  of  the 
field.  The  resistor  is  of  ample  capacity  for  several 
successive  field  interruptions,  such  as  might  occur  in 
maneuvering. 

A  duplicate  field  discharge  resistor  is  located  in 
the  engine  room,  and  is  connected  in  series  with  an 
electrolytic  cell  directly  across  the  field  terminals. 
This  is  installed  as  additional  insurance  against  1 
breakdown  of  the  field  which  might  occur  if  the  field 
discharge  circuit  in  the  control  room  should  ever  be- 
come impaired.  The  cell  takes  a  slight  charging  cur- 
rent when  the  field  is  being  excited.  When  the  excit- 
ing circuit  is  interrupted,  the  cell  breaks  down  upon 
the  reversal  of  the  polarity  across  its  terminals  and 
allows  the  discharge  current  to  pass  through  and  be 
absorbed  in  the  resistor. 

OIL   CIRCUIT  BREAKER   EQUIPMENT 

The  alternating-current  generator  and  motor  cir- 
cuits are  controlled  by  manually  operated  oil  circuit 
breakers  which  are  capable  of  interrupting  their  rated 
currents  at  full  voltage,  but  their  operating  levers  are 
so  interlocked  with  the  field  and  steam  control  that 
they  cannot  normally  be  opened  under  full  power. 
The  steam  supply  to  the  turbine  is  partially  cut  off  and 
the  generator  field  circuit  is  opened  before  the  breakers 
can  be  opened.  The  generators  are  never  operated  in 
parallel,  so  that  the  breakers  never  have  more  than  the 
power  of  one  generator  behind  them.  The  circuit 
breakers  have  no  automatic  features.  The  breakers 
are  operated  in  pairs.  There  are  two  breakers  in  par- 
allel for  each  generator  circuit  and  for  the  tie  circuit. 
The  reversing,  pole  changing  and  secondary  short-cir- 
cuiting of  the  motors  is  done  as  if  the  two  motors  on 
one  side  of  the  ship  were  one  unit. 

The  generator,  tie  and  motor  reversing  breakers 
are  equipped  with  self  contained  disconnecting  devices 
so  that  any  circuit  breaker  can  be  isolated  and  inspected 
with  safety  even  though  the  ship  is  under  way.  Ex- 
cept for  the  tie  breakers,  which  are  three-pole,  the 
breakers  having  disconnecting  devices  are  two-pole  and 
the  third  lead  is  isolated  by  opening  the  disconnects. 
This  arrangement  was  adopted  to  reduce  operating 
effort. 


DISCONNECTING  A  PROPELLING  MOTOR 

A  propelling  motor  can  be  completely  isolated  from 
the  bus-bars  in  a  few  minutes  time  by  lowering  its 
ahead  and  astern  circuit  breakers,  thus  opening  the  dis- 
connects, and  by  removing  the  pins  which  connect  the 
breakers  to  the  operating  levers.  If  the  outboard 
motors,  for  example,  have  been  disconnected,  opera- 
tion can  be  resumed  using  the  inboard  motors,  and  the 
levers  are  manipulated  exactly  as  they  were  before. 
The  pole  changing  circuit  breakers  of  the  idle  motors 
are  not  disconnected  from  their  operating  levers  as 
these  are  dead  when  the  disconnects  of  both  reversers 
are  open. 

ARRANGEMENT    OF    CONTROLS 

The  general  arrangement  of  the  control  room  is 
shown  in  several  illustrations  in  this  issue.  The  opera- 
tors face  forward  and  have  all  levers,  instruments, 
gauges  and  lamp  indicators  within  close  range,  as  shown 
in  Fig.  3. 

The  oil  circuit  breakers  for  the  generator,  tie  and 
motor  primary  circuits  are  mounted  in  cells  in  a  steel 
structure  in  front  of  the  operating  space.  The  four 
motor  secondary  oil  circuit  breakers  and  the  two  double 
liquid  rheostats  are  located  behind  the  operating  space, 
as  shown  in  Fig.  4.  The  field  contactors,  discharge  re- 
sistors and  booster  rheostats  are  mounted  on  the  out- 
board motor  room  bulkheads.  Fig.  5  shows  a  works 
assembly  of  the  primary  structure  for  one  of  the  later 
ships  having  the  same  equipment. 

All  operations  are  done  from  the  operating  space 
except  the  opening  of  the  disconnects  and  the  removal 
of  the  pin  to  disengage  a  breaker  from  the  lever  me- 
chanism. These  two  operations  are  done  from  the 
narrow  aisles  next  to  the  forward  bulkhead  and  under 
the  instrument  board.  Tank  removal  and  contact  in- 
spection is  done  from  the  center  aisle  of  the  primary 
structure.  The  cells  have  a  removable  door  at  each 
end  for  access  to  the  breakers. 

The  bus-bars  and  connections  above  the  circuit 
breakers  are  of  bare  copper  straps  fastened  together 
with  brass  bolts,  and  are  rigidly  supported  against  dis- 
tortion from  any  cause.  The  bus-bar  supports  have 
molded  bakelite  insulators  with  clamped  fittings  and  a 
pair  of  steel  angles,  between  which  the  bars  are  held 
by  brass  bolts.  All  high  voltage  bus-bars  are  enclosed 
with  expanded  metal  screens  to  prevent  accidental 
contact  with  live  parts.  The  voltage  transformers 
with  their  primary  fuses  and  resistors  are  located 
above  the  center  aisle  of  the  primary  structure  and  are 
made  accessible  by  unbolting  and  dropping  hinged 
steel  doors.  The  controllers  for  the  liquid  rheostat 
pump  motors  are  supported  from  the  upper  tanks  of  the 
rheostats. 

OPERATING  LEVERS 

The  operating  levers  are  mechanically  interlocked 
to  insure  the  proper  sequence  of  operation  and  are  di- 
vided into  three  groups  for  operation  and  are  manipu- 


208 


THE  ELECTRIC  JOURNAL 


Wo\.  XVIII,  No.  5 


lated  by  three  men   under  orders   from  the  officer  of 
the  watch. 

The   central   operator  has   control   of   the    follow- 
ing:— 

Two  field  levers. 

Two  wheel  operated  main  turbine  governor  control   valves. 

Two    governor    stop   motor   reversing    controllers,    mounted    on    th« 

control    valves. 
T\  ;■    .     'It:'      trip.s,    mounted    overhead. 


1- 

Wk 

^ 

SI 

^^m 

H 

JE^W 

Wm 

^1 

Wmli  \ 

"uiMm 

i 

,. /J 

1  l\  /.sc^B^^^^^^H 

FIG.   3 — CONTROL  ROOM    OPER.\TING    LF-VERS    .\NU    INSTRL'MIiNT   BO.\RD 
AS  VIEWED  FROM  THE  PORT  SIDE 

The  operator  on  the  port  side  has  control  of  the 
following: 

Two  generator  breaker  levers. 

One  motor   tie   breaker   lever. 

Two  motor   reverser   levers.    Ahead   and   Back. 

One  liquid  rheostat  valve  lever. 

One   motor   secondary   breaker   lever. 

Two  pole  changer  levers,  24  pole  and  36  pole. 

The  operator  on  the  starboard  side  has  control  of 
six  levers  which  correspond  to  the  six  end  levers  on  the 
port  side  or  the  last  four  items  listed. 

The  levers  have  distinctive  coloring  to  make  it 
easier  to  observe  the  set-up  which  an  operator  has 
made.  The  Ahead  and  Back  levers  are  colored  white 
and  red  respectively,  to  correspond  with  the  engine 
order  telegraph  dials  and  are  equipped  with  signal  con- 
tacts which  are  so  connected  with  the  telegraphs  that 
a  buzzer  is  sounded  if  the  operator  throws  a  lever  con- 
trary to  signal.  The  36  pole  levers  are  colored  green 
to  distinguish  them  from  the  adjacent  24  pole  primary 
and  secondar}'  equipment  levers  which  are  black.  The 
generator,  tie  and  field  levers  are  also  painted  black. 

SEQUENCE  OF  LEVER  OPERATIONS 

The  following  are  the  lever  operations  for  various 
running  conditions.  The  turbogenerator  is  running  at 
approximately  35  percent  speed,  and  all  levers  are  open 
and  the  speed  wheel  is  on  zero. 

Condition  i  :-~Operating  one  generator  with  motors  on  the 
24  pole  connection. 

A — To  start: — 

1 — Close  the  tie  circuit  breaker  lever. 

2 — Close  the  breaker  lever  of  the  generator  in  use.  (Discon- 
nects for  idle  generator  circuit  breaker  open,  unless  it  is 
desired  to  have  generator  standing  by  for  immediate  service 
in  case  of  emergency.) 

S — Close   the   24   pole    circuit  breaker   levers   on   both   sides. 

4 — Close   the   ahead    circuit   breaker   levers   on   both    sides. 

6 — Close  the  field  lever  hard  over  and  bring  it  back  several 
notches  immediately.  The  motors  are  now  energized  and 
will   start    to   rotate. 

6 — Close   the   rheostat   valve  levers  on  both   sides 

7 — When    the   liquid    in    the    rheostats    has   reached    its    maximum 


both   sidi's. 


signal,    and    proceed 


level    as    observed    from    the    gauge    glasses,    close    the    sec- 
omiHry   short    ciriuitmg    breaker   levers   on    bolli    M.les 

8 — Open   the   valve   levers   on  both  sides   to   drop   the   liquid    level 
and   prepare   the  rheostats  for  the  next   operation. 

9 — Adjust  the  turbine  speed  and  generator  excitation  to  the 
rroper  running  values.  Adjust  the  governor  stop  setting  so 
as  to  prevent  any  sudden  increase  of  load  being  taken  by 
the  turbine  from  any  cause.  The  excitation  must  not  be 
allowed  to  fall  below  a  certain  value  for  any  given  speed  or 
the  motors  will  fall  out  of  step.  Stable  operating  condi- 
tions are  observed  from  the  electrical  instruments. 
B — ^To  stop: — 

1 — Sat   steam  wheel  for  slow   speed. 

2 — Open    field    lever. 

■■i — .|.en    the   secciiuiary   short-circuiting   levi 

4 — Open  ahead  levers  on  both  sides. 
C— To   back   on   one   or   both   sides;— 

1 — Close    the    reversing    levers    according    t         „  ^ ^,, 

according     to     instructions    under    headings"   1-A-B    to*^  iIa's 
above. 

Condition  2 : — Operating  two  generators  with  motors  on  the 
24  pole  connection. 

This  differs  from  Condition  i  in  that  both  eenerator  breaker 
levers  are  closed,  the  tie  breaker  lever  is  open,  both  steam 
wheels  and  both  field  levers  are  manipulated  and  the  port  and 
starboard  field  interlock  bars  operate  independently. 

Condition  3 : — Operating  one  generator  with  motors  on  the 
36  pole  connection. 
A — To    start:— 

1 — Bring  the  motors  up  to  speed  on  the  24  pole  connection  as 
per  instructions  for  Condition  1.  (Before  changing  over 
wait  several  minutes  until  the  ship  has  picked  up  a  speed 
ahead  corresponding  to  the  propeller  revolutions,  otherwise 
the  motors  will  draw  heavy  currents  and  may  fall  out  of 
Ktep). 
2 — Set  steam  wheel  for  slow  speed. 
3 — Open   field   lev-er. 

■t — Open   the  sei-onoary  short-circuiting  levers  on  botli  sides. 
5 — Open   24   pole  levers  on  both   sides. 
6 — Close   36  pole  levers  on  both  sides. 
7 — Close   field   lever. 
8 — Adjust   speed. 

B — To  stop: — 

1 — Set  steam  wheel  for  slow  speed. 

2 — Oi>en  field  lever. 

3 — Open   36  pole   levers   on   both   sides. 

4 — Open  ahead  levers  on  both  sides.  , 

6 — Close   24   pole  levers  on   both   sides. 

(Interlocks  prevent  backing  on  the  36  pole  connection  and 
the  procedure  in  backing  is  the  same  as  uncT^r  Condi- 
tion    1-C     above.) 

ALTERXAXING-CURRENT  GROUND  DETECTOR  SYSTEM 

Each  alternating-current  generator  circuit  has  con- 
nected to  it  three  voltage  transformers,  duplicates  of 
those  used  for  operating  the  instruments,  which  are 
star  connected  with  the  neutral  point  grounded  on  the 


FIG.  4— CONTROL  ROOM  OPERATING  LEVERS,  LIQUID  RHEOSTATS  AND 
MOTOR  SECONDARY  BREAKERS  AS  VIEWED  FROM   THE  STARBOARD  SIDE 

high-voltage  side,  and  delta  connected  with  a  voltage 
relay  inside  the  delta  on  the  low-voltage  side.  Each 
relay  actuates  an  auxiliary  relay,  and  these  in  turn  com- 
plete a  buzzer  circuit  to  warn  the  operator  of  a 
ground.     The  contacts   of   the  auxiliary   relay   remain 


June,  19JI 


THE  ELECTRIC  JOURNAL 


269 


closed,  thus  continuing  the  alarm  until  the  relay  con- 
tacts are  opened  by  hand. 

The  voltage  relay  does  not  operate  in  the  case  of 
clear  circuits,  as  the  three  secondary  voltages  are  bal- 
anced. In  case  of  a  low  resistance  ground  on  one  lead, 
one  transformer  becomes  short-circuited,  thus  impress- 
ing full  generator  voltage  across  each  of  the  remaining 
two  and  the  vector  sum  of  the  two  transformer  second- 
ary voltages  across  the  relay. 

Ordinarily  the  ship  will  be  stopped  upon  the  warn- 
ing of  a  ground  and  the  grounded  lead  isolated,  but  if 
an  emergency  demands  that  operation  continue,  the  re- 
lay can  be  disconnected  to  silence  the  alarm. 

ELECTRICAL  INSTRUMENTS  ON  CONTROL  ROOM   BOARD 

The  electrical  instruments  have  black  dials  with 
white  lettering  and  pointers  and  the  scales  are  specially 
marked  to  facilitate  taking  quick  readings.  The  fol- 
lowing instruments  are  installed  for  the  propelling  ma- 
chinery,  the  alternating-current   instruments  being  op- 


FIG.  5 — THE  CONTROL  ROOM   PRIM.^RY  STRUCTURE 

erated  from  current  and  voltage  transformers  of  suit- 
able ratio. 

For  Each  Turbogenerator 

One  alternating-current,  4000  ampere  ammeter. 

One    alternating-current,    4000    volt    voltmeter. 

One     alternating-current,     single     phase,      15  000     kw.     wattmeter, 

marked    for   three-phase   lialanced   power. 
One   Ircquency   meter   marked    in   r.p.m.,    with   three    scales   to   in- 

the  24  pole  connection  and  of  the  motors  on  the  36  pole  con- 
nect^ion. 

One   three-phase    power-factor   meter. 

One    stability    indicator. 

One    direct-current,    400    ampere   field   ammeter. 

One    direct    .urr.-nt.    4)0    volt.    HhIiI    voltnut.-r 

One  main   turbine   governor   stop   position   indicator. 

One  main  turbine  revolution  indicator,  3000  r.p.m.,  magneto  op- 
erated. 

For  Each  Motor  : — 

One  alternating-current  ammeter  with  two  scales,  one  1600  am- 
peres for  the  motors  on  the  24  pole  connection  and  the  other 
800    amperes    for    the   motors   on    the   36    pole   connection. 

One  alternating-current,  single  phase  watthour  meter,  connected 
to   record    balanced    three-phase   power. 

One  shaft  revolution  indicator  200-0-200  r.p.m.,  magneto  oper- 
ated. 

All  instrument  transformer  secondary  leads  come 
to  terminal  boards  above  the  main  panels  for  conveni- 
ence in  inserting  testing  instruments  and  for  disconnect- 
ing the  instrument  wiring.  Rear  connected  knife 
switches  having  testing  terminal  posts  on  the  front  are 
provided  for  all  circuits.  The  current  switches  are 
double  throw,  and  have  their  blades  arranged  so  that 
the  circuit  is  not  broken  in  short-circuiting  the  current 
transformers  or  when  inserting  testing  instruments. 


The  most  important  electrical  instruments  are  the 
motor  ammeters,  the  stability  indicators  and  the  field 
ammeters.  The  specified  propeller  speed  is  obtained 
by  adjusting  the  turbine  speed,  indications  of  the 
former  being  obtained  from  regular  readings  of  the 
mechanical  revolution  counter.  The  magneto-voltme- 
ter speed  indicators  give  instantaneous  values  of  tur- 
bine and  propeller  speed  and  are  useful  for  detecting 
anything  abnormal  in  the  operation  of  the  machinery. 

The  motor  ammeters  are  sensitive  indicators  of  the 
load  being  carried  by  the  motors,  and  of  when  the  mo- 
tors have  fallen  out  of  step  with  the  generators.  If 
the  rudder  is  thrown  hard  over  to  the  right  the  star- 
board motor  ammeters  will  indicate  much  higher  cur- 
rents than  the  port  motor  ammeters,  showing  that  the 
starboard  propellers  have  the  greater  load.  The  sta- 
bility indicator  shows  when  the  voltage  of  the  genera- 
tor is  sufficient  to  enable  the  generator  to  cany  the  load 
safely  under  the  given  conditions. 

A  certain  field  current  is  necessary  for  maintaining 
r.  safe  generator  voltage  for  any  given  speed  and  con- 
dition of  operation.  The  field  voltmeter  in  connection 
with  the  field  ammeter  serves  the  purpose  of  giving  the 
operators  a  general  idea  of  the  temperature  of  the  gen- 
erator field. 

The  wattmeter  shows  the  power  delivered  to  the 
propelling  motors.  Shaft  horsepower  can  be  calculated 
from  the  wattmeter  reading  by  allowing  for  motor  effi- 
ciency. The  power-factor  meter  gives  a  fairly  good 
idea  of  operating  conditions  in  that  it  is  an  indicator  of 
the  relative  excitation.  A  high  power-factor  indicates 
an  economical  excitation  while  a  low  power-factor  in- 
dicates an  excessive  excitation. 

GAUGES   ON   THE   CONTROL  ROOM    BOARD 

Black  dial  gauges  having  white  markings  and  red 
markers  to  indicate  the  working  pressures  are  installed 
for  indicating  the  operating  condition  of  the  prime 
mover  systems.  One  gauge  panel  is  provided  for  each 
engine  room  and  the  gauges  are  connected  to  the  fol- 
lowing points: — feed  water  system,  main  steam  line, 
main  turbine  steam  chest,  first  stage  inlet,  auxiliary  ex- 
haust, main  condenser  vacuum,  forced  lubrication  for 
bearings,  governor  control  valve  oil  supply  and  oil  line 
to  the  governor. 

OTHER    INSTRUMENTS    ON    THE    CONTROL    ROOM    BOARD 

The  center  panel  carries  red  lamp  indicators  for 
the  240  volt  direct-current  feeders  from  the  engine 
rooms,  green  and  red  lights  for  the  main  turbine  power 
limiting  devices  and  white  lights  for  the  main  turbine 
throttles.  It  also  has  mounted  on  it  the  rudder  in- 
dicator, the  time  clock  and  the  revolution  counter.  The 
counter  is  mechanically  connected  through  disengaging 
clutches,  shafts  and  gearing  to  the  four  propeller  shafts. 
The  revolution  counter  gives  the  following  records  and 
indications : — 

a — Revolutions  of  the   individual  shafts. 

b — Average  revolutions  of  the  port,    starboard    and   all   shafts. 

c — Average    r.p.m.    of    port,    starboard    and    all    shafts    can    be    ob- 


270 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


tained  by  holding  a  train  of  gears  in  engagement  for  30  sec- 
onds. 

d — A  movable  pointer  indicates  on  a  dial  the  relative  average 
speeds  of  th«  port  and  starboard  shafts,  which  side  is  run- 
ning  the   faster   and   how   much. 

e — Two  additional  sets  of  counters,  only  one  set  being  in  opera- 
tion at  one  time,  are  clutched  in  electrically  from  the  bridge 
and  are  used  to  record  the  all  shafts  average  revolutions  for 
any  distance  traveled  by  the  ship. 

TEMPERATURE    INDICATOR    FOR   THE    ALTERNATINo 
CURRENT   MACHINES 

Each  generator  and  propelling  motor  has  six 
thermocouples  imbedded  in  its  stator  windings,  whereby 
the  temperature  in  the  slot  can  be  read  on  a  potentio- 
meter mounted  on  the  control  room  board.  Three  of 
the  motor  couples  are  in  the  24  pole  winding  and  the 
other  three  are  in  the  36  pole  winding. 

A  link  arrangement  is  used  for  connecting  three 
ot  the  six  couples  of  each  machine  to  a  pair  of  dial 
switches  and  readings  of  only  the  three  hottest  couples 
in  the  case  of  the  generators  and  the  three  couples  in 
the  operating  winding  in  the  case  of  the  motors  are 
taken  on  any  run.  The  instrument  measures  tempera- 
tures up  to  200  degrees  C.  Seven  conductor  cable  con- 
sisting of  six  copper  and  one  advance  conductor  connect 
the  couples  in  the  machines  to  the  instrument  panel  in 
the  control  room.  This  cable  is  made  up  in  accordance 
with  Navy  practice  for  interior  communication  cable. 


Varnished  cambric  insulation  is  used  on  all  cables 
installed  in  machinery  spaces.  The  direct-current 
cables  are  covered  with  a  lead  sheath  and  a  steel  armor 
overall  and  the  largest  single  conductor  cable  used  is 
800000  circ.  mils.  Round  duplex  cables  are  used  for 
two  wire  circuits  having  conductors  not  larger  than 
60000  circ.  mils.  The  armored  cables  are  cleated  di- 
rectly to  the  steel  work. 

Triplex  cable  is  used  for  the  3400  volt  alternating- 
current  primary  circuits  and  for  the  motor  secondary- 
circuits,  each  conductor  being  300000  circ.  mils,  and 
each  cable  carrying  three-phase  power.  Two  or  more 
three-phase  cables  are  connected  in  parallel  depending 
upon  the  current  to  be  carried. 

The  alternating-current  cable  was  made  up  in  ac- 
cordance with  the  recommendations  of  a  special  com- 
mittee of  the  A.  I.  E.  E.  which  co-operated  with  the 
Navy  Department  on  the  general  problem  of  cables  for 
electrically   driven   ships.     The   cable   insulation   is   of 


black  varnished  cambric  and  there  are  two  coverings, 
the  inner  of  reinforced  rubber  and  the  outer  of  lead! 
The  manufacturer's  test  voltage  on  the  cable  was  20  000 
volts  for  one  minute.  The  rubber  sheath  forms  a 
moisture  proof  protection  for  the  cable  in  case  the  lead 
.--heath  becomes  damaged. 

The  alternating-current  cables  terminate  in  special 
triplex  terminals  which  have  a  wiped  lead  joint  with 
the  cable  sheath.  The  outlets  for  the  individual  con- 
ductors are  made  moisture  tight  by  special  taping  and 
the  terminal  is  finally  filled  with  insulating  gum.  The 
uisulators  through  which  the  individual  insulated  con- 
ductors pass  are  of  bakelite. 

The  primary  cables  carry  not  more  than  375  am- 
peres under  ma.ximum  conditions  and  the  inductive 
ciTects  of  their  currents  are  practically  neutralized. 
It  is  thus  possible  to  run  the  alternating-current  cables 
around  and  through  steel  work  and  bulkheads  at  will 
without  the  necessity  of  taking  special  precautions. 
The  cable  sheaths  are  not  insulated  frf)m  the  cable  sup- 
jorts,  as  there  is  no  tendency  for  sheaih  currents  to  be 
mduced.  The  cable  rests  in  a  pair  of  malleable  iron 
blocks  and  a  split  lead  sleeve  is  used  between  the  sheath 
;md  the  blocks  for  protecting  the  sheath  against  wear. 
Ihe  cable  is  supported  approximately  every  two  feet. 

Brass  bushings  having  rounded  edges  and  liberal 
bearing  surfaces  are  used  where  the  cable  pierces 
plates.  Individual  stuffing  tubes  are  used  where  the 
cable  pierces  watertight  bulkheads  at  right  angles.  For 
other  angles,  a  cast  bulkhead  plate,  through  which  all 
the  cables  pass,  is  used  to  make  a  watertight  joint  with 
the  bulkhead. 

The  alternating-current  generator  leads  are  taken 
out  below  to  a  set  of  bus-bars  to  which  eight  triplex 
cables  are  connected.  These  cables  run  through  the 
pump  rooms  and  terminate  above  the  bus-bars  of  the 
control  room  structure.  The  motor  cables  leaving  the 
control  room  consist  of  two  for  the  36  pole  leads,  four 
tor  the  24  pole  leads  and  six  for  the  secondary  leads. 

The  motor  cables  terminate  on  short  bus-bars  above 
the  motors  and  flexible  single  conductor  500000  circ. 
mil  braid  covered  cables  connect  from  the  bus-bars  to 
the  motor  terminals.  These  flexible  cables  are 
readily  disconnected  from  the  motor  and  can  be  swung 
out  of  the  way  when  it  is  necessary  to  move  the  stator 
forward  for  the  inspection  or  repair  of  the  motor. 


Lighting  Sets 


e  U.  S,  S.  Teiiii<5ssee 


POWER  for  the  auxiliaries  and  for  lighting  on  the 
Tennessee  is  furnished  by  six  300  kw,  240/120 
volt,  three-wire  generators,  driven  by  steam  tur- 
bines. Four  of  these  turbines  are  built  to  operate  con- 
densing; the  other  two  operate  noncondensing  and  ex- 
haust into  the  feed  water  heating  system.  The  speed  of 
the  turbines  is  6000  r.p.m.,  which  is  reduced  through 
gears  to  900  at  the  generator.  The  noncondensing  tur- 
bines are  capable  of  developing  one-third  overload  for 
two  hours,  when  operating  with  250  lbs.  steam  pressure 
and  10  lbs.  back  pressure.  The  condensing  turbine 
will  carry  one-third  overload  when  operating  at  200  lbs. 
steam  pressure  and  25  in.  vacuum  or  300  kw  with  200 
lbs.  steam  pressure  and  atmospheric  exhaust. 

The  noncondensing  turbines  are  of  the  single  disc 
type  with  one  row  of  blades,  the  blade  speed  being  about 
600  ft.  per  second.  There  are  two  nozzles  with  valves 
arranged  so  that  either  nozzle  can  be  closed,  the  dimen- 
sions of  the  nozzles  being  such  that  with  the  large  nozzle 
open  about  60  percent  of  the  total  capacity  of  the  ma- 
chine can  be  carried,  and  with  the  small  nozzle  open, 
slightly  less  than  40  percent  can  be  carried.  Each 
nozzle  has  a  suitable  reversing  chamber  for  re-directing 
the  steam  upon  the  rotor  blades. 

The  condensing  turbine  is  of  the  single-flow  com- 
bination type,  consisting  of  a  three-row  impulse  element 
followed  by  fourteen  rows  of  reaction  blading.  The 
glands  on  the  turbine  spindle  are  of  the  water  seal  type 
and  therefore  no  steam  escapes  around  the  shaft  on  the 
noncondensing  units,  and  no  air  gets  into  the  cylinders 
or.  the  condensing  sets. 

The  governor  is  of  the  flyball  type  and  is  quite 
powerful.  It  is  mounted  inside  of  the  reduction  gear 
casing.  This  location  of  the  governor  is  very  satisfac- 
tory, particularly  as  it  permits  of  generous  lubrication 
of  the  moving  parts  of  the  governor  without  the  escape 
of  oil  from  the  machine. 

The  oil  pump  is  driven  from  an  extension  of  the 
governor  spindle  and  is  located  in  the  bottom  of  the 
gear  case,  which  sert^es  as  a  reservoir  for  the  lubricat- 
ing oil.  The  oil  from  the  pump  discharges  through  a 
strainer  located  on  top  of  the  gear  case,  and  is  so  ar- 
ranged that  should  the  strainer  become  clogged  the  oil 
overflows  to  the  passage  which  leads  to  the  bearings. 
If  the  oil  pump  discharges  more  oil  than  the  bearing 
will  take,  the  level  of  the  oil  in  this  strainer  box  raises  a 
httle  higher  and  the  excess  oil  overflows  through  a  pass- 
age leading  back  to  the  reservoir.  This  strainer  box  is 
provided  with  a  cover  which  can  be  lifted  off  to  ex- 
amine the  oil  and  observe  the  flow  at  any  time  when  the 
machine  is  operating.  At  the  same  time  the  oil  strainer 
can  be  rt  loved  for  cleaning  without  interrupting  the 


J.  A.  MacMURCHY  and  ALBERT  O.  LOOMIS 

Small  Turbine  Eng.  Dept  General  Eng.  Dept, 

Westinghouse  Electric  &  Mfg.  Company 

operation  of  the  machines 


A  hand  pump  is  provided 
for  pumping  oil  through  the  system  before  starting. 

An  emergency  overspeed  governor  is  furnished  to 
close  the  throttle  valve  should  the  turbine  overspeed  ten 
percent.  This  device  consists  of  a  small  weight  carried 
in  a  casing  attached  to  the  turbine  spindle  and  designed 
sv  that  the  centrifugal  force  on  the  weight  is  overbal- 
anced by  the  pressure  of  a  spring,  until  the  speed  has 
been  reached  at  which  the  device  should  operate.  As 
the  weight  moves  out,  the  centrifugal  force  on  the 
weight  increases  much  more  rapidly  than  the  scale  of 
the  spring,  so  that  the  weight  snaps  out  quickly,  once  it 
starts  to  move.  In  its  outer  position,  this  emergency 
overspeed  governor  weight  strikes  a  small  lever  which 
unlatches  a  fairly  heavy  weight  which,  falling  freely, 
unlatches  the  throttle  valve  spring,  causing  the  valve 
to  close  instantly. 

Rather  elaborate  provisions  are  made  to  guard 
against  the  possibility  of  the  throttle  valve  being  opened 
ai  a  time  when  the  exhaust  valve  is  closed.  On  the 
turbine  cylinder  there  is  mounted  a  small  signal  valve, 
which  will  blow  when  the  pressure  in  the  cylinder 
reaches  about  15  lbs.,  thus  indicating  to  the  operator 
that  he  has  an  improper  pressure  in  the  cylinder.  The 
throttle  valve  can  be  closed  instantly  by  pulling  a  small 
lever  adjacent  to  the  hand  wheel.  If  the  pressure 
builds  up  to  20  lbs.,  an  automatic  device  instantly  closes 
the  throttle  valve.  If,  however,  the  pressure  builds  up 
to  25  lbs.,  a  large  relief  valve  on  the  turbine  cylinder 
will  open  and  prevent  the  pressure  exceeding  50  lbs. 
with  the  throttle  valve  wide  open  and  the  exhaust  valve 
closed.  This  latter  relief  valve  is  piped  to  atmosphere. 
Ir>  addition,  both  hand  and  electrical  devices  are  pro- 
vided for  closing  the  throttle  valve  from  a  distance. 
The  noncondensing  turbines  are  not  equipped  with  the 
device  to  close  the  throttle  valve  automatically  at  a  pre- 
determined pressure  in  the  turbine  cylinder,  as  these 
machines  serve  as  exciters  to  the  main  unit  and  it  was 
thought  better  to  avoid  any  possible  risk  of  this  device 
shutting  down  the  turbine,  should  the  back  pressure 
build  up. 

The  governor  valve  is  connected  directly  to  the 
governor  without  the  intervention  of  any  form  of  relay. 
The  noncondensing  turbines  have  only  one  governor 
valve.  The  condensing  turbines  have  two  valves,  the 
primary  valve  being  designed  to  pass  sufficient  steam  to 
carry  full  load  when  the  turbine  is  operating  condensing 
and  the  secondary  valve  being  designed  to  carry  one- 
third  over-load  when  the  turbine  is  operating  condens- 
ing. To  carry  the  full  load  on  the  condensing  turbines 
when  they  are  operating  noncondensing  a  hand  by-pass 
valve  is  provided. 


272 


THE  ELECTRIC  JOURNAL 


Vol.  XMII,  No.  6 


The  lubricating  oil  is  cooled  by  passing  it  through 
an  oil  cooler  as  it  is  discharged  from  the  pump  on  its 
way  to  the  bearings.  The  cooler  is  similar  to  a  small 
surface  condenser,  with  the  cooling  water  passing 
through  the  tubes  and  the  oil  passing  several  times  back 
and  forward  over  the  tubes. 


FIC.   I — TURBINE  E.NU  \1K\V  OK  30O  KW  UIKECT-CURRENT  GEARED 
LIGHTING   SET 

An  interesting  feature  of  these  generator  sets  is 
that  the  generator  is  built  with  only  one  bearing,  the  in- 
board bearing  being  omitted  and  that  end  of  the  shaft 
coupled  solidly  to  the  gear  shaft,  in  this  way  greatly 
improving  the  operation  and  at  the  same  time  affecting 
a  very  material  reduction  of  the  length  of  the  unit. 

The  reduction  gears  are  of  the  Melville-MacAlpin 
type  and  have  the  pinion  located  on  top  of  the  gear,  so 
that  the  turbine  and  generator  are  on  the  same  center 
line. 

GENERATORS 

The  generators  are  of  the  same  type  for  both  the 
condensing  and  the  noncondensing  sets.  Each  has  a 
cast  steel  frame  split  on  a  horizontal  center  line.  Spe- 
cial field  pole  construction  makes  possible  very  close 
voltage  regulation. 

The  main  poles  are  laminated  and  are  located  sym- 
metrically with  respect  to  the  center  line  of  the  frame. 
The  commutating  poles,  which  are  shorter  than  the 
main  poles,  are  of  solid  steel.  These  are  offset  from  the 
center  line  of  the  frame  and  lie  toward  the  rear  of  the 
machine.  By  this  means  the  length  of  the  wiring 
around  the  frame  connections  for  the  commutating 
poles  is  made  a  minimum.  There  are  six  main  poles 
and  six  commutating  poles. 

The  brushholder  brackets  are  carried  by  a  cast-iron 
rocker  ring  which  fits  into  a  recess  in  the  field  frame. 
The  brush  arms  are  of  the  washboard  type,  made  of 
cast-iron.  The  ends  of  these  are  fastened  rigidly  to  a 
rmg  formed  of  seginents  of  micarta.  Brass  brush- 
holders  of  the  box  type  are  used.  The  brushholder 
springs  have  a  special  enamel  finish  baked  on.  Bolts 
and  nuts  one-half  inch  in  size  or  under  are  sherardized. 

The  armature  is  of  such  size  that  the  punchings  are 
keyed  on  the  spider.  Mica  insulated  armature  coils  are 
held  in  open  slots  by  fiber  wedges.     Banding  is  used  to 


secure  the  front  and  rear  portions  of  the  coils  extend- 
ing beyond  the  core. 

The  commutator  is  built  upon  a  spider  which  is 
pressed  and  keyed  onto  the  shaft.  Four  brass  collector 
rings,  which  are  shrunk  on  a  mica-covered  cast  iron 
bub,  are  pressed  onto  the  shaft  in  front  of  the  commu- 
tator. The  current  from  the  collector  rings  is  con- 
ducted by  means  of  cables  which  pass  through  the  deck 
plates  within  the  bedplate  recess  under  the  commutator, 
to  two  compensators  or  balance  coils  mounted  on  the 
engine  room  bulkhead.  From  the  middle  points  of  these 
coils  the  neutral  wire  of  the  three-wire  system  is  taken. 
The  compensator  windings  consist  of  four  pan-cake 
coils  mounted  in  shell  type  punchings.  The  individual 
coils  are  bakelized,  varnished  and  dried  thoroughly. 
The  assembled  coils  and  punchings  are  dipped  four 
limes  in  a  suitable  varnish  and  baked  after  each  dip- 
ping. 

When  used  with  these  compensators  the  genera- 
tors, operating  at  240  volts  with  an  unbalanced  load  of 
43  percent,  will  maintain  a  voltage  balance  of  not  less 
than  117  and  not  more  than  123  volts  between  the  neu- 
tral and  outside  wires. 

The  terminals  are  arranged  for  six  650000  circ.  mil 
cables  for  the  main  leads  and  four  650000  circ.  mil 
cables  for  the  equalizer  leads.  The  shunt  field  leads, 
positive  main  and  half  of  the  equalizer  leads  are  on  one 
side  of  generator;  the  remaining  leads  are  on  the  other 
side.  The  terminals  on  both  sides  are  covered  by  brass 
screens. 

The  shunt  held  rheostat  is  designed  for  a  total 
range  of  close  adjustment  from  five  percent  above  to 
ten  percent  below  rated  voltage.  The  variation  is  not 
more  than  one  volt  per  step  between  230  and  250  volts 
at  full  load.  The  rheostat  has  sufificient  resistance  to 
reduce  the  voltage  almost  to  zero  with  the  machine  on 
open  circuit,  comparatively  high  resistance  steps  being 
used  on  the  lower  end  of  the  range.     A  rheostat  with 


JK     hSil     wr.A     .Jt     jlAJ     KV.      i^,.xL 
CONDENSING  TURBINE  SET 


two  face  plates  is  used.  A  total  of  158  contact  buttons 
are  connected  to  tube  type  resistor  units  between  the 
face  plates.  Contact  arms  are  staggered  so  that  voltage 
.-djustment  is  possible  over  154  steps. 

In  order  to   take  the  generator  off  the  line  auto- 
matically when  the  overspeed  governor  or  the  overpres- 


June,  1921 


THE  F.LRCTRIC  JOURNAL 


273 


sure  trip  has  functioned  and  the  throttle  valve  closes, 
the  circuit  breaker  trip  switch  is  mounted  near  the 
upper  end  of  a  trip  weight  lever.  Whenever  this  lever 
is  released,  either  by  the  action  of  the  overspeed 
governor,  by  the  overpressure  trip  or  by  hand,  an  elec- 
trical connection  is  made  through  a  spring  closed  switch 
to  the  shunt  trip  coil  of  the  engine  room  circuit  breaker. 
'I'his  disconnects  the  set  electrically. 

In  addition  to  furnishing  power  for  the  engine  room 
auxiliaries,  it  is  intended  that  the  noncondensing  units 
will  supply,  in  connection  with  the  booster  sets,  excita- 
tion for  the  main  propulsion  generators.  However,  by 
means  of  suitable  switchboard  connections,  the  con- 
densing sets  also  can  be  made  to  serve  this  purpose. 


Should  lioth  booster  sets  become  inoperative,  volt- 
rge  adjustment  of  one  of  the  300  kw  generators, 
to  which  only  the  fields  of  the  main  generators  are  con- 
nected, will  make  it  possible  with  but  little  incon- 
venience, for  the  ship  to  proceed  under  full  power,  if 
necessary.  The  voltage  adjustment  of  these  sets  is  in- 
tended for  this  purpose  only  in  an  emergency. 

All  the  generators  are  flat  compounded  to  within 
one  volt  either  way  from  240  volts  normal  at  no-load 
r?nd  full-load  points.  The  variation  from  a  straight 
line  drawn  between  the  no-load  voltage  point  and  a 
point  halfway  between  the  full-load  points  of  the 
ascending  and  descending  curves  does  not  exceed  four 
volts. 


fer  tlvD  U>  ^,  S.  TBjiiis^^eD 


JOHN  H.  SMITH  and  P  LBERT  O.  LOOMIS 

Condenser  Ivii;.   Dept.  General  Rng.  Dept. 

Wcstinghouse  Electric  &  Mfg.  Companj'. 


THE  condensing  apparatus  serving  each  of  the 
main  turbines  in  each  engine  room  of  the  Ten- 
nessee consists  of:  One  main  surface  condenser; 
one  main  condenser  circulating  pump;  one  main  conden- 
ser condensate  pump ;  three  main  condenser  air  ejectors  ; 
and  one  main  condenser  air  separator. 

The  condensing  apparatus  serving  each  of  the  300 
kvv  condensing  units  in  each  engine  room  consists  of 
one  dynamo  surface  condenser ;  one  dynamo  condenser 
circulating  pump;  one  dynamo  condenser  condensate 
pump ;  two  dynamo  condenser  air  ejectors ;  and  one  dy- 
namo condenser  air  separator. 

MAIN  SURFACE  CONDENSERS 

The  main  surface  condensers  contain  approximate- 
ly II  616  sq.  ft.  of  cooling  surface,  measured  on  the  out- 
side of  the  tubes.  Each  condenser  is  equipped  with 
6604,  5/8  in.  outside  diameter.  No.  16  BWG  tubes,  hav- 
ing an  active  length  of  10  ft.  9  in.  The  arrangement  of 
tubes  and  design  of  the  water  boxes  are  such  as  to 
cause  the  cooling  water  to  make  two  passes  through  the 
tubes. 

The  condenser  shells  are  made  of  boiler  plate.  Th.: 
exhaust  trunk,  or  breeches  connection  between  the  tur- 
bine exhaust  openings  and  the  condenser  is  integral  with 
the  condenser  shell  and  is  also  made  of  boiler  plate. 
The  condenser  shell  is  rigidly  seated  in  a  steel  cradle, 
the  turbine  and  condenser  expansion  being  raken  up  by 
copper  expansion  joints  inserted  between  turbine  ex- 
haust openings  and  the  exhaust  trunk. 

The  condenser  is  designed  to  produce  vacua  nor 
less  than  shown  in  Table  I,  measured  in  the  turbine  ex 
haust  chamber,  when  condensing  the  quantities  of  steam 
and  circulating  the  quantities  of  60  degrees  F.  water 
therein  tabulated. 


MAIN    CONDENSER    CIRCL'LATING    PUMP 

The  circulating  pump  for  supplying  cooling  water 
to  the  main  condenser  is  of  the  double  inlet  volute  sin- 
gle-stage type  with  two  runners,  as  shown  in  Fig.  i. 
The  casing  is  divided  into  two  parts,  at  the  axis,  and 
in  a  horizontal  plane.  The  suction  and  discharge  con- 
nections are  integral  with  the  lower  half  of  the  pump 
casing,  thus  allowing  easy  removal  of  the  upper  half 
without  disturbing  any  connection  of  piping  or  the 
foundation. 

The  rotating  element  consists  of  two  bronze  runners 
and  a  steel  shaft  covered  with  keyed  bronze  sleeves  to 
hold  the  runners  in  position,  and  to  protect  the  shaft 


TABLE  I— CONDENSER  PERFORMANCE 

Lbs.  Steam  Condensed 
per  Hour 

Gallons  per  Minute^ 
Water  Circulated 

Guaranteed  Vac- 
uum Referred 
to  30  in.  Bar. 

159750 
109540 
106850 
40100 

1 0000 
15000 
15000 
9500 

28.4 
28.67 
28.7 
29-15. 

from  the  corrosive  action  of  sea  water.  For  furthfer 
protection,  red  fibre  packing  rings  are  inserted  between 
the  sleeves  and  the  runners.  In  fact,  all  parts  coming 
in  contact  with  water  are  made  of  bronze 

The  main  circulating  pump  is  motor  driven  and 
with  its  drive  is  mounted  on  a  continuous  bed  plate. 
The  pump  is  direct  connected  to  the  motor  by  a  flexible 
coupling. 

The  set  is  designed  for  adjustable  speeds  because 
the  maximum  capacity  of  the  pump  is  greater  than  the 
capacity  required  for  normal  operation,  thus  permitting 
It  to  be  operated  at  the  proper  speed  to  suit  any  condi- 
tions of  circulating  water  temperature  or  load  on  the 
condenser.  For  this  reason,  the  pump  is  operated  with 
the  suction  and  discharge  valve  wide  open,  thus  insur- 


274 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


ing  maximum  pump  efficiency  incident  to  any  speed. 
This  pump  has  a  maximum  capacity  of  19000  gallons 
per  minute  against  a  total  head  of  30  ft.  at  a  speed  of 
700  r.p.m..  It  is  driven  by  a  235  hp  motor  having  speed 
adjustment  from  350  to  700  r.p.m. 

An  Open  Motor,  with  split  frame  and  brackets,  is 
used.  Drip  proof  canopy  covers  have  been  added  sim.e 
installation  on  shipboard.  For  marine  service,  the  arma- 
ture insulation  is  given  special  moisture  resisting  treat- 
ment. To  prevent  the  spilling  of  oil  due  to  the  rolfing  of 
the  ship,  caps  are  used  on  the  oil  stand  pipes.  The  bear- 
ing housings  are  provided  on  the  inside  with  felt  gaskets 
through  which  the  shaft  passes.  These  gaskets  prevent 
the  passage  of  oil  into  the  motor  windings  or  out  upon 
the  commutator. 

The  Controller  has  a  multiple  switch  starter  me- 
chanically interlocked  with  the  main  circuit  breaker. 
The  armature  resistance  is  cut  out  in  six  steps.  The 
switches  are  interlocked  so  that  they  will  close  in  pro- 
per sequence,  each  switch  being  locked  in  by  the  switch 
which  follows  it,  and  the  entire  group  being  held  closed 
by  the  main  circuit  breaker.  The  interlock  arm  moves, 
whether  the  circuit  breaker  is  being  closed  or  opened, 
so  that  the  starter  is  tripped  before  the  circuit  breaker 
contacts  are  made,  in  case  the  starting  switches  have 


FIG.    I — MAIN    CIRCULATING    PUMP 

been  closed  in  advance  of  the  circuit  breaker.  The  no- 
voltage  trip  for  this  controller  is  on  the  circuit  breaker. 

The  motor  is  stopped  by  tripping  the  circuit  break- 
er and  the  starting  switches  open  automatically  upon  the 
opening  of  the  circuit  breaker.  Its  speed  is  regulated 
by  a  separate  field  rheostat.  A  shunt  contactor  con- 
trolled by  a  vibrating  relay  in  the  armature  circuit  short 
circuits  the  field  rheostat  during  starting.  The  relay 
opens  after  the  starting  operation  is  completed  and  the 
motor  automatically  comes  up  to  the  speed  correspond- 
ing to  the  setting  of  the  field  rheostat. 

The  armature  resistors  for  the  auxiliary'  motors  arc 
designed  to  carry  150  percent  normal  load  for  one 
minute,  and  200  percent  normal  load  for  twenty  seconds 
without  reaching  a  temperature  which  is  injurious  to 
the  material. 

EJECTING  EQUIPMENT 

In  the  removal  of  non-condensible  vapors  and  con- 
densate from  the  condenser  it  is  desirable  to  cool  the 
former  as  much  as  possible,  while  it  is  equally  undesira- 


ble to  cool  the  latter,  which  is  to  be  returned  at  once 
to  the  boiler.  In  most  surface  condenser  installations, 
this  is  accomplished  by  withdrawing  the  noncondensi- 
ble  vapor  and  condensate  separately,  the  former  after 
it  has  been  cooled  by  contact  with  a  bank  or  cold  tubes, 
isolated  for  that  purpose,  the  latter  with  as  little  tube 
contact  as  possible  after  condensation  has  occurred. 

When  separate  machines  are  used,  tjie  system  is 
described  as  "wet  and  dry."  This  system  is  employed 
on  the  Tennessee,  where  high  vacuum  is  required, 
However,  in  many  plants  the  owners  have  seen  fit  to 
compromise  in  the  matter  of  final  temperatures,  and  to 
remove  both  noncondensible  vapors  and  condensate  with 
z  single  pump.  This  system  is  described  as  "wet,"  and 
IF  also  employed  on  the  Tennessee  to  serve  in  the  cap 
acity  of  a  stand-by.  The  system  as  installed  comprises 
independent  condensate  pumps,  air  ejectors  and  air  sep- 
arators. 

CONDENSATE  PUMPS 

The  main  condenser  condensate  pump  is  of  the 
vertical    shaft,   double    inlet,   volute,    single-stage   type, 

with    a    single    runner.     The 

casing    is    divided    into    two 

parts  on   a   horizontal    plane, 

perpendicular  to  the  axis  of 

the     pump.      The     complete 

rotating    element,    the    gland 

and    bearing,     are     integral 

with   the   upper  half  of   the 

casing.     The   lower  half,   or 

pump  body,  carries  both  the 

inlet     and     water    discharge 

connections,    thus   permitting 

easy  removal  of  the  top  half, 

including   the    rotor,    without 

disturbing  any  connection  of 

piping     or     the     foundation. 

This  pump  has  but  one  bear- 
ing, which  acts  merely  as  a 

guide,  and  it  is  lubricated  by 

water  from  the  discharge  of 

the    pump.     The    weight   of 

the   rotor   is   carried  by   the  ^■^^•^ 
thrust  bearing  of  the  motor. 

The  suction  side  of  the  pump  casing  is  equipped 
with  a  vent  connection,  to  relieve  the  pump  constantly 
of  any  accumulation  of  vapor,  which  has  a  tendency  to 
be  given  off,  owing  to  the  water  approaching  the  boiling 
point  of  tlie  vacuum  at  the  pump  suction.  The  presence 
of  this  vapor  would  cause  the  pump  to  become  "vapor 
botind."  In  other  words,  instead  of  the  pump  runner 
being  constantly  full  of  water  alone,  it  would  be  filled 
with  part  water  and  part  vapor.  This  vent,  therefore, 
is  connected  to  the  air  piping  between  the  condenser 
and  the  ejector,  and  is  arranged  as  direct  as  possible,  in 
order  to  free  the  interconnecting  piping  of  any  pockets 
that  might  otherwise  prevent  proper  drainage  to  the 
pump. 


INDENSATE  PUMP 


June,  1921 


THE  ELECTRIC  JOURNAL 


275 


The  slightest  air  leak  on  the  suction  side  of  the 
pump  will  result  in  reduced  capacity  and  consequent 
loss  of  efficiency.  For  this  reason  the  gland  is  fitted 
with  a  water  seal,  the  sealing  water  being  supplied 
from  a  source  separate  from  the  pump.  In  addition  to 
this  an  extra  precaution  against  air  leaks  is  provided  in 
that  the  stuffing  box  is  under  pressure  from  the  dis- 
charge of  the  pump.  A  slight  water  leak  along  the 
shaft  indicates  that  the  gland  is  sealed,  and  since  this 
leakage  is  fresh  water,  it  is  led  to  the  drain  tank  to 
which  is  led  the  drainage  from  the  main  turbine. 

Motor — The  characteristic  of  the  condensate  pump 
is  such  that  the  head  it  will  discharge  agamst  is  practi- 
cally constant  for  varying  amounts  of  condensate;  there- 
fore adjustable  speeds  are  unnecessary.  This  pump, 
however,  is  driven  by  a  19  hp,  1700  r.p.m.,  adjustable- 
speed  compound  wound  motor  and  while  the  capacity 


FIG    .3 — SHIPBOARD  INSTALLATION  OF  MAIN  CONDENSATE  PUMP 
AND  MOTOR  CONTROL 

is  considerably  greater  than  the  requirements  of  service, 
an  increase  in  head  will  result  from  an  increase  in 
speed.  The  pump  is  designed  for  a  capacity  of  500 
gallons  per  minute  against  a  total  head  of  70  feet. 

The  assembly  of  the  unit  without  the  canopy  cover 
IS  shown  in  Fig.  2.  A  speed  adjustment  from  1400  to 
1700  r.p.m.  is  possible.  Marine  fittings  arc  employed. 
A  ship's  roll  up  to  30  degrees  will  not  cause  the  spilling 
of  oil  from  motor  bearings.  A  canopy  drip-proof  cov- 
er has  been  installed  over  the  motor,  as  shown  in  Fig.  3. 

Controller — The  controllers  for  the  engine  room 
pump  motors  are  located  close  to  the  motors  which  they 
control,  as  shown  in  Fig.  3,  and  are  provided  with  a 
two-pole  overload  time  limit  circuit  breaker,  a  manually- 
operated  starting  rheostat  and  no-voltage  protection. 
The     circuit   breaker  has    independently    closing   arms 


and  serves  also  as  the  line  switch.     Speed  regulation  is 
obtained  by  field  control. 

The  controllers  for  all  motors  of  25  hp  and  below 
have  starting  and  field  regulating  rheostats  of  the  slid- 
ing arm  type,  arranged  so  that  the  motors  are  started 
on  full  field.  The  rheostat  has  two  arms,  tlie  upper  for 
the  field  contacts  and  the  lower  for  the  armature  con- 
tacts. The  upper  arm  has  the  handle  and  carries  the 
lower  arm  with  it  when  starting  the  motor.  After 
both  arms  have  been  moved  to  the  running  position  the 
starting  arm  is  held  by  the  no  voltage  mechanism  and 
the  field  arm  is  moved  back  to  increase  the  motor 
speed  to  the  desired  value.  The  motor  is  stopped  by 
tripping  the  circuit  breaker,  and  the  rheostat  automati- 
cally returns  to  the  off  position,  the  starting  arm  carry- 
ing the  field  arm  with  it. 

AIR  EJECTOR 

The  main  condenser  air  ejector  is  an  apparatus  foi 
removing  air  from  the  condenser  at  a  low  absolute  pres- 
sure by  means  of  steam  jets,  to  compress  and  exhaust 
the  air  against  atmospheric  pressure.  All  parts  entering 
into  the  construction  of  the  Westinghouse  LeBanc  aii' 
ejector,  Fig  4,  are  of  bronze.  The  ejector  consists  of 
two  stages  arranged  in  series.     The  first  stage  includes 


FIG.  4 — SECTION  THROUGH   MAIN  CONDENSER  AIR  EJECTOR 

a  single  expanding  nozzle  which  receives  steam  from 
the  upper  steam  chest,  and  after  expanding  it  to  the  de- 
sired pressure,  discharges  it  through  a  receiving  cham- 
ber into  the  combining  tube  and  diffuser.  The  receiv- 
ing chamber  communicates  with  the  condenser  where  the 
air  is  entrained  by  friction  of  the  air  with  the  steam  jet. 
The  discharge  end  of  the  first  stage  delivers  the  fluid 
traversing  it,  to  the  inlet  end  of  the  second  stage 
ejector.  The  outlet  of  this  diffuser  is  surrounded  by 
a  series  of  expanding  nozzles  which  receive  and  expand 
the  second  stage  steam  to  the  desired  pressure,  dis- 
charging it  into  the  lower  mixing  chamber.  The  mix- 
ture from  the  first  and  second  stage  ejectors  is  further 
compressed  and  discharged  through  the  diffuser  to  a 
line  leading  to  the  air  separator. 

The  ejector  requires  no  adjusting,  so  that  the  only 
trouble  that  may  be  experienced  is  the  clogging  up  of 
the  nozzle  throats.  If  the  steam  strainers  are  cleaned 
regularly  this  will  not  occur.  It  has  a  further  advan- 
tage over  other  classes  of  air  removal  machinery  in  that 
it  utilizes  high  velocities  in  the  removal  of  the  air,  which 
is  accomplished  by  the  friction  of  the  air  with  the  fine 
jets  of  steam,  resulting  in  the  smallest  possible  piece  of 


276 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


apparatus.  On  the  other  hand,  in  the  case  of  recipro- 
cating pumps,  the  air  is  removed  by  displacement  which, 
at  a  high  vacuum,  requires  a  machine  of  large  cubical 
content,  owing  to  the  large  volume  of  air  to  be  handled. 
When  supplied  with  steam  having  a  pressure  at  the 
ejector  inlet  of  125  lb.  per  sq.  in.  gage,  each  ejector 
serving  the  main  condenser  has  an  air  removal  capacity 
of  36  lb.  of  free  air  per  hour,  when  exhausting  air  from 


FIG.    5 — SECTION   THROUGH    .MAIN    CONDENSER   AIR    SEPARATOR 

a  2iS  in.  vacuum,  and  27  lb.  ]ier  hour  from  a  28.5  in. 
vacuum,  referred  to  a  30  in.  barometer.  Three  ejec- 
tors are  supplied  for  service  in  connection  with_  each 
main  surface  condenser,  two  of  which  will  remove  the 
air  under  normal  conditions  of  operation,  the  other 
serving  as  a  stand-by. 

THE  ilAIN   CONDKNSKR  AIR  SEPARATOR 

The  air  separator,  shown  in  Fig.  5,  receives  the 
air  and  steam  from  the  ejectors,  one  separator  being 
furnished  in  connection  with  the  three  ejectors  serving 
each  main  condenser.  The  function  of  the  air  separa- 
tor is  to  condense  the  ejector  steam,  and  automatically 
separate  the  entrained  air  which  is  allowed  to  escape  to 
the  atmosphere  through  the  air  vent  ai  the  top,  thus 
insuring  complete  separation  of  air.  The  air  separator, 
is  in  reality,  a  combination  jet  and  surface  condenser. 
The  jet  condenser  uses  as  a  condensing  fluid  the  con- 
densate from  the  main  unit;  the  surface  condenser  re- 
ceives cooling  water  from  the  main  circulating  system. 

Under  normal  conditions  of  operation,  there  is  suf- 
ficient condensate  to  condense  the  steam  in  the  jet  por- 
tion of  the  separator,  in  which  case  all  the  heat  of  the 
motive  steam  is  regained  in  heating  the  feed  water.  Dur- 
ing times  of  light  load,  when  there  is  not  enough  main 
unit  condensate  to  condense  the  ejector  steam  such  con- 
densation takes  place  in  the  surface  portion  of  the  sep- 
arator, so  that  the  loss  of  heat  from  this  source  is  prac- 
tically negligible.  Thus  the  efficiency  of  the  ejector  is 
practically  100  percent. 

From  the  separator  the  condensate  overflows  into 
the  feed  and  filter  tank.  The  air  separator  weighs  ap- 
proximately 1425  lb.  It  contains  90  sq.  ft.  of  cooling 
surface,  requires  200  gallons  per  minute  of  cooling  wa- 


ter,  and  has   a   capacity   for  4400   lbs.   of   steam   and 
195  000  lbs.  of  condensate  per  hour. 

OIL  COOLER  CIRCULATING  PUMP 

Except  for  the  fact  that  this  is  a  single-runner  pump, 
and  of  comparatively  smaller  capacity,  the  pump  for 
circulating  the  cooling  water  for  the  oil  cooler  is  the 
same  as  the  main  circulating  pump,  in  so  far  as  con- 
struction, materials,  etc,  are  concerned.  It  has  a 
capacity  of  300  gallons  per  minute  against  a  total  head 
of  115  feet  and  is  driven  by  an  18  hp  motor  running  at 
a  speed  of  1750  r.p.m.  Fig.  6  shows  this  unit  as  in- 
stalled on  shipboard.  One  oil  cooler  circulating  pump 
is  installed  in  each  engine  room.  A  canopy  is  placed 
over  the  motor,  as  shown,  to  protect  the  windings  from 
dripping  condensate,  leaking  steam,  water  and  oil.  That 
this  precaution  is  necessary  is  obvious  from  number  of 
pipes,  valves  etc.  shown  in  the  vicinity  of  this  set.  A 
controller  similar  to  that  shown  in  Fig,  3,  is  used  to  give 
a  speed  adjustment  of  583  to  1750  r.p.m. 

LUBRICATING  OIL  PUMPS 

The  lubricating  oil  pumps  are  of  the  rotating 
plunger  type.  Each  pump  is  capable  of  delivering  250 
gallons  of  lubricating  oil  at  100  to  160  degrees  F.  again^l 
a  discharge  head  of  185  feet  with  a  maximum  pump 
speed  of  600  r.p.m.  Fig.  7  shows  the  motor-driven 
unit  installed  on  the  Tennessee. 

The  rotation  of  the  cylindrical  piston  on  the  cam 
drive  shaft  produces  a  vacuum  in  the  cylinder.  This 
causes  the  oil  to  flow  through  the  suction  port  and  fol- 
low the  piston  until  the  cylinder  is  completely  filled. 
The  port  in  the  piston  slide  is  then  closed  mechanically, 
and  remains  so  until  the  cam  or  piston  has  completed 
its  full  revolution.  When  the  piston  passes  the  suction 
port  it  automatically  opens  the  discharge  port,  and  im- 


FIG.    6— SHII'l:C)\Rn    INSTAI.L.\TION    OF   THE   OIL   COOLER   CIRCULATING 
I'UMP 

mediately  begins  forcing  the  oil   out  into  the  cylinder 
chamber,  at  the  same  time  drawing  in  a  new  supply. 

All  parts  of  the  pump  except  the  drive  shaft  are 
arranged  in  duplex,  opposed  at  an  an^le  of  180  degrees. 
There  is  no  mechanical  contact  between  the  pistons  and 
the  cylinder.     The  ports  are  not  congested  by  valves 


June,  1 92 1 


THE  ELECTRIC  JOURNAL 


277 


or  springs.  A  25  hp,  400  to  600  r.p.m.  compound- 
wound  motor  is  directly  connected  to  the  lubricating  oil 
pump. 

In  addition  to  the  two  motor-driven  pumps 
described  above,  two  similar  pumps  are  turbine  driven 
through  reduction  gears.  The  latter  are  used  as  a  Stand- 
by, and  come  into  service  when  the  drop  in  oil  pressure 
for  the  bearings  reaches  that  value  for  which  the  auto- 
matic starting  valve  is  set.  An  overspeed  governor 
prevents  the  speed  of  the  driving  turbine  from  exceed- 
ing a  predetermined  safe  value. 

DYNAMO   CONDENSING   SYSTEM 

The  apparatus  used  in  connection  with  the  four  300 
kw  condensing  units,  two  of  which  are  installed  in  eacii 
engine  room,  is  of  the  same  general  construction  as 
that  used  for  the  main  units,  though  of  relatively  lower 
capacities. 

The  Circulating  Pump  supplies  the  dynamo  con- 
denser with  cooling  water,  and  is  designed  to  have  a 
capacity  of  2000  gallons  per  minute  against  a  total  head 
of  20  feet.  It  is  driven  by  a  17  hp.  motor  running  at  a 
speed  of  700  r.p.m.  Like  the  main  condenser  circula- 
ting pump,  it  is  an  adjustable  speed  pump,  thus  permit- 
ting operation  at  the  proper  speed  to  suit  any  condition 
of  circulating  water  temperature  and  load  on  the  con- 
denser. 

The  Condensate  Pump  withdraws  the  conden.satc 
from  the  dynamo  condenser,  and  is  designed  to  have  a 
capacity  of  75  gallons  per  minute  against  a  total  head 
of  70  feet.  It  is  driven  by  a  6  hp.  motor  which  has  an 
adjustable  speed  rating  of   1500  to   1800  r.p.m.  and  i; 


of  the  dynamo  condenser,  two  air  ejectors  are  in- 
stalled, one  of  which  has  sufficient  capacity  to  remove 
the  accumulated  air,  while  the  other  serves  as  a  stand- 
by. Fig.  8  shows  the  manner  in  which  these  ejectors 
are  mounted  on  shipboard. 


FIG.   7 — MOTOR  DRIVEN  LUBRICATING  OIL  PUMP 

simdar  in  construction  to  the  vertical  motor  driving  the 
mam  condenser  condensate  pump. 

The  Air  Ejector  has  a  free  air  removal  capacity 
of  18  lbs.  per  hour  when  exhausting  air  from  28  in. 
vacuum  referred  to  a  30  inch  barometer.     In  the  case 


FIG.   8— MOUNTING  OF   AIR  EJECTOR  ON    SHlrllO.\l<ll 

Air  Separator — As  in  the  case  of  the  main  conden- 
ser, one  air  separator  is  installed  in  each  engine  room  to 
receive  and  condense  the  exhaust  steam  from  the  ejec- 
tors serving  the  dynamo  condenser,  the  entrained  air 
being  automatically  separated  and  allowed  to  escape 
through  a  vent  at  the  top.  The  air  separator  is  identi- 
cal in  construction  with  the  main  condenser  air  separa- 
tor, though  of  relatively  smaller  capacity.  It  contains 
35  sq.  ft.  of  cooling  surface,  requires  100  gallons  per 
minute  of  cooling  water,  and  has  a  capacity  for  1980 
lbs.  of  steam  and  1 10  000  lbs  of  condensate  per  hour.  It 
weighs  approximately  850  lbs. 

ELECTRIC  MOTOR  DRIVE 

The  large  proportion  of  electrically-driven  engine 
room  auxiliaries  is  noteworthy.  Where  there  is  alread}- 
sufficient  exhaust  steam  available  for  feed  water  heat- 
ing, heating  of  the  ship,  etc.,  the  electric  motor  drive  is 
more  economical  than  that  of  steam.  This  is  especially- 
true  in  connection  with  the  small  ratings  required  for 
all  but  the  main  circulating  pumps.  Weight  is  reduced 
to  a  minimum  for  these  small  motor  drives.  The  speed 
of  the  motor  can  be  made  suitable  for  the  application 
without  the  use  of  reduction  gears.  This  may  be  ex- 
emplified in  the  case  of  the  two  forms  of  drive  for  the 
oil  pumps  which  operate  at  600  r.p.m.  In  this  particu- 
lar instance  the  motor-driven  outfit  has  also  the  advan- 
tage of  lower  first  cost.  Obviously  the  motor-driven 
pump  will  be  less  noisy  and  attended  with  less  vibration 
than  the  geared  turbine  drive,  and  the  weights  of  the 
two  types  are  nearly  the  same.  For  auxiliaries  in  the 
above  class,  the  first  cost  of  the  electric  drive  is 
usually  a  trifle  more  than  that  of  the  steam  drive.  The 
more  efficient  operation  of  the  former  ovfer  the  latter 
is  the  chief  reason  justifying  electrical  equipment.  A 
further  important  consideration  is  the  fact  that  ?he  cost 
of  maintaining  electric  feeder  cables  is  less  than  that  of 
steam  lines  and  the  care  of  the  electric  equipment  it- 
self is  not  so  great  as  that  of  steam. 


o'{  iho  ^ocoiiclarlo^  nf  xho  Main 


W.  C.  GOODWIN 

Control  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Companj' 


THE  speed  control  of  the  main  propelling  motors 
of  the  Tennesee  is  obtained  by  varying  the  pri- 
mary voltage  and  frequency,  this  being  done  at 
the  turbogenerator.  In  order  to  accelerate  the  mo- 
tors up  to  speed  to  allow  the  short-circuiting  of  the 
motor  secondaries,  as  in  starting,  and  in  order  to  de- 
celerate and  accelerate  the  motor  in  the  opposite  di- 
rection as  in  stopping  or  reversing  the  ship,  liquid 
rheostats  are  used  for  inserting  and  cutting-out  resist- 
ance in  series  with  the  secondary  windings.  There 
are  four  propelling  motors  and  so  four  rheostats  arc 
used.  However,  the  rheostats  are  made  in  pairs,  or 
two  double  rheostats,  as  the  construction  is  conven-ent, 
econoinical  of  space  and  allows  the  operation  of  both 
rheostats  of  the  pair  in  case  of  an  accident  to  one 
pump,  motor,  or  motor  supply  line. 

One  of  the  double  rheostats  is  shown  in  Fig.  i.  It 
consists  of  a  .sheet  steel  tank,  two  sets  of  electrode 
units,  a  cooling  system  and  two  motor  driven  centri- 
fugal pumps.  The  tank  has  two  main  sections,  of 
which  the  lower  is  the  liquid  storage  tank  and  contains 
the  liquid  cooling  coils.  The  upper  section  is  divided 
into  three  sections,  consisting  of  two  electrode  cham- 
bers (one  for  each  motor)  and  between  them  a  smaller 
chamber  knovi'n  as  the  "overflow  chamber,"  the  bottom 
of  which  opens  into  the  lower  or  storage  tank. 

The  storage  tank  is  the  reservoir  for  the  elec- 
trolyte and  also  contains  the  cooling  coils  of  the  cool- 
ing system.  Outside  and  on  each  end  of  this  tank  is 
mounted  a  direct-current  shunt  motor,  a  centrifugal 
pump,  outlet  and  inlet  pipes  and  valve.  The  pump  re- 
ceives its  liquid  from  the  bottom  of  the  storage  tank 
and  delivers  it  to  the  bottom  of  the  electrode  chamber 
above. 

Each  of  the  two  electrode  chambers  has  two 
electrolyte  inlets  and  two  outlets.  The  main  inlet  is 
at  the  bottom  towards  the  end  and  is  the  direct  supply 
from  the  pump.  Above  this  inlet  is  an  insulated  bar- 
rier which  prevents  jetting  above  the  inlet  and  distri- 
butes the  flow  over  the  electrode  chamber.  The  second 
inlet  is  an  opening  between  the  two  electrode  chambers 
and  is  normally  closed  by  a  valve.  This  valve  is  op- 
ened in  an  emergency  when  one  pump  or  its  motor 
is  out  of  service,  and  then  the  other  pump  supplies  the 
two  electrode  chambers  with  electrolyte.  The  two 
outlets  in  each  electrode  chamber  are  located  in  the 
wall  of  the  common  overflow  chamber  at  different 
levels  and  they  determine  the  height  of  the  liquid  in 
the  electrode  chamber.     The  lower  of  these  openings 


is  controlled  by  a  butterfly  valve  which  is  opened  and 
closed,  together  with  the  similar  valve  m  the  other 
electrode  chamber,  through  a  system  of  levers  and  bell 
cranks  by  a  control  lever  on  the  operaimg  stand  itt 
the  control  room.  This  valve,  when  open,  keeps  the 
level  of  the  liquid  down  to  the  minimum  liquid  level. 
The  upper  opening  or  outlet  is  a  rectangular  weir  and 
determines  the  upper  or  maximum  liquid  level  in  the 
chamber. 

The  cover  plate  of  the  electrode  chamber  carries 
the  electrodes  by  means  of  special  moulded  insulators. 


^  -tJ 

1^^ 

1 ^ 

> 

l^^^^^l 

^H 

^B^ 

^^^^^H^ 

m 

W 

Bj 

^^HHt'K 

BHm^^K^ 

HI 

J^ 

^S^l 

^^ 

w 

■ 

FIG.   I — DOUBLE  LIQUID  RHEOSTAT 

The  complete  electrode  unit  can  be  raised  or  removed 
for  examination  and  insulator  cleaning  by  means  of  the 
eye  bolts  on  the  cover.  The  complete  electrode  unit 
is  shown  in  Fig.  2. 

The  electrodes  consist  of  parallel  steel  plates, 
There  are  seven  long  plates  for  the  three  phases,  the 
two  outer  ones  being  of  the  same  phase  in  order  to 
give  approximately  equal  resistance  between  phases. 
With  the  liquid  at  low  level  the  seven  plates  only  are 
immersed  and,  as  they  are  relatively  far  apart  and  the 
contact  area  with  the  electrolyte  is  small,  a  high  resist- 
ance between  phases  is  obtained.  Shorter  electrodes 
are  placed  between  the  seven  long  plates  in  order  to 
decrease  the  resistance  between  7>hases  more  than  the 


June,  1 92 1 


THE  ELECTRIC  JOURNAL 


279 


proportionate  rise  in  liquid  level  would  give  and  to 
obtain  a  low  resistance  across  the  motor  slip  rings  be- 
fore short-circuiting  them.  The  ratio  of  maximum  re- 
sistance to  minimum  resistance  with  one  definite  per- 
centage of  electrolyte  is  15  to  i.     The  electrolyte  is  a 


FIG  2 — COMPLETE  ELECTRODE  UNIT 

Electrodes  are  suspended  from  cover  plate  of  the  electrode 
chamber. 

low  percentage  solution  of  sodium  carbonate.  The 
level  of  the  liquid  and  its  temperature  can  be  observed 
by  a  liquid  level  gauge  and  thermometer  in  each  elec- 
trode chamber. 

The  operation  can  be  followed  by  referring  to  Fig. 
3.  The  electrolyte  flows  continually  from  the  storage 
tank  through  the  pump  to  the  electrode  chamber  and 
through  the  lower  overflow  to  the  overflow  chamber 
and  back  into  the  storage  tank.  The  rate  of  flow  can 
be  adjusted  by  the  speed  of  the  pump  motor  and  by  the 
valve  in  the  pump  supply  line.  The  lower  overflow 
is  kept  open  in  the  normal  ojf  condition,  and  so  the 
high  resistance  is  maintained  in  readiness  for  accelera- 
tion or  deceleration  of  the  propelling  motors.  With 
the  generated  voltage  and  frequency  at  a  predetermined 
value  and  the  proper  set-up  switches  closed,  the  op- 
erator moves  the  liquid  rheostat  lever,  and  this  lever 
closes  the  lower  overflow  and  the  electrolyte  rises  at 
a  predetermined  rate  in  the  electrode  chamber,  until 
it  runs  over  the  upper  overflow.  The  increased  im- 
mersion of  the  electrodes  decreases  the  resistance  be- 
tween electrodes  of  the  different  phases.  The  elec- 
trode terminals  of  the  phases  are  connected  to  the  slip 
rings  of  the  secondary  of  the  motor  and  so  the  resist- 
ance between  slip  rings  is  decreased.  When  the  opera- 
tor observes  in  the  gauge  that  the  maximum  level  has 
been  reached,  he  throws  the  secondary  lever  which 
closes  a  circuit  breaker,  thus  short-circuiting  the  mo- 
tor secondary's  slip  rings.  The  liquid  rheostat  lever 
is  then  moved  to  the  initial  position  to  open  the  lower 
overflows  and  the  liquid  is  lowered  to  the  minimum 
level  to  be  in  readiness  for  another  operation. 


The  amount  of  resistance  and  the  rate  of  decreas- 
ing the  resistance  are  determined  not  from  the  start- 
ing of  the  main  motor  from  rest  to  full  speed,  but 
rather  for  the  condition  of  reversing  from  full  speed 
ahead  to  full  speed  astern.  When  the  ship  is  going 
full  speed  ahead  and  the  power  is  cut  off  from  the 
propeller  motors,  the  speed  of  the  propellers  will  drop 
to  approximately  seventy  percent  of  the  full  speed. 
To  bring  the  propeller  to  rest  and  to  reverse  it,  the 
motor  primary  is  connected  to  the  line  for  the  opposite 
rotation  and  the  motor  is  then  rotating  ar  170  percent 
slip,  based  on  full  speed  astern.  To  bring  the  propel- 
ler to  rest,  it  is  necessary  to  exert  nearly  full-load 
torque  during  part  of  the  deceleration  time,  and  over 
25  percent  of  full-load  torque  to  hold  the  propeller  it 
rest.  Before  reversing,  the  turbogenerator  is  adjusted 
to  give  half  voltage  and  half  frequency  on  the  motor 
primary.  The  resistance  between  phases  of  the  rheo- 
stat at  minimum  level  is  made  to  give  the  full-load 
torque  at  near  170  percent  slip.  The  resistance  at 
maximum  level  is  made  sufficiently  low  to  bring  the 
motor  speed  near  enough  to  synchronous  at  full-load 
torque  to  allow  the  short-circuiting  of  the  secondary 
slip  rings  with  150  percent  of  full-load  moror  current. 
The  time  required  to  decelerate  and  accelerate  the  pro- 
peller, shaft  and  motor  rotor  from  full  speed  ahead 
to  full  speed  astern  is  based  on  the  propeller  charac- 
teristics and  the  moments  of  the  parts.  With  normal 
speed  of  the  pump  motors  and  with  the  pump  valve 
open,  approximately  fifteen  seconds  are  required  for 
the  liquid  to  rise,  and  twenty  seconds  for  it  to  fall. 

As  the  rheostats  are  not  used  for  speed  control  of 
the  propelling  motors,  they  only  need  to  be  able  to  take 
care  of  a  certain  number  of  consecutive  starts  and  re- 


FIG.  3 — CROSS  SECTION  OF  DOUBLE  LIQUID  RHEOSTAT 

versals.  The  rheostats  are  located  in  the  main  con- 
trol room  and  immediately  behind  the  operator's  plat- 
form and  levers,  one  double  rheostat  on  each  side  of 
the  center.  The  cooling  coils  in  the  storage  tanks  are 
adapted  to  use  sea  w-ater. 


R    T    PIERCE 

Supply  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


WHEN  alternating-current  motors  were  adopted 
for  the  propulsion  of  battleships,  there  were 
many  new  problems  which  had  to  be  solved. 
One  of  these  was  to  produce  an  indicator  that  would 
show  when  the  induction  motors  were  near  or  at  the 
drop-out  point. 

The  speed  of  the  ship  is  controlled  by  changing  the 
frequency  applied  to  the  motors,  the  power  output  of 
the  generators  and  the  number  of  poles  on  the  motors. 
At  each  operating  speed  of  the  ship,  there  is  a  value  to 
v.'hich  the  field  excitation  can  be  reduced  and  which  is 
sufficient  to  hold  the  motors  in  step.  It  is  desirable  to 
operate  the  ship  on  as  low  a  fuel  consumption  as 
possible  and  therefore  any  reduction  that  can  be  made 
in  the  field  excitation  is  a  direct  gain  due  to  the  decrease 
in  the  sum  total  of  losses.  Also  with  the  lower  excita- 
tion, and  thus  the  lower  voltage,  the  power-factor  of 
the  system  is  improved.  However  there  is  danger  that 
the  excitation  will  be  reduced  to  the  range  of  unstable 
operation  and  the  motors  will  pull  out  of  step.  To 
avoid  this  difficulty  and  to  show  how  near  the  un- 
stable point  the  particular  running  condition  is,  the 
stability  indicator  was  developed. 

This  instrument.  Fig.  i,  consists  of  two  elements 
v.hose  moving  systems  are  mounted  on  the  same  shaft, 
and  whose  torques  oppose  each  other.  One  is  an  alter- 
Hating-current  ammeter  element  whose  indications  are 
relatively  independent  of  frequency  throughout  the 
ranges  used,  and  which  measures  the  current  which  the 
generator  feeds  to  the  system.  The  other  element  is  an 
alternating-current  voltmeter  which  has  a  reactor  in 
place  of  the  usual  resistance,  so  that  its  indications  are 
inversely  proportional  to  frequency  and  directly  propor- 
tional to  the  generator  voltage.  The  quantity  which  is 
measured  by  this  voltage  element  is  a  function  of  the 
excitation  of  the  generator  field.  Therefore,  for  a 
given  running  condition,  if  the  field  excitation  is  re- 
duced, the  generator  voltage  is  reduced  and  the  voltage 
clement  of  the  stability  indicator  becomes  weaker.  At 
the  same  time  the  current  which  the  generator  feeds  to 
the  system  increases  and  the  current  element  of  the  sta- 
bility indicator  becomes  stronger.  This  causes  the  in- 
strument to  indicate  on  that  portion  of  the  scale  which 
shows  that  the  decrease  in  excitation  is  approaching  an 
unsafe  operating  condition. 

When  the  excitation  is  raised,  the  voltage  of  the 
generator  becomes  higher  and  the  line  current  becomes 
lower,  causing  the  voltage  element  of  the  stability  in- 
dicator to  have  a  relatively  greater  effect  than  the  cur- 
rent element,  so  that  the  instrument  will  indicate  that 
the  excitation  is  higher  than  necessary.     H  the  field  ex- 


citation is  increased  further,  the  induction  motors  will 
chaw  an  excessive  amount  of  wattless  current  which 
will  cause  an  increase  in  the  current  output  of  the  gener- 
;i1or.  This  increase  in  current  may  be  sufficient  actually 
1(1  overcome  the  effect  of  an  increase  in  voltage  and  the 
indicators  of  the  instrument  will  tend  to  show  that  this 
.s  a  poor  operating  condition,  but  not  to  the  same  extent 
that  a  decrease  in  excitation  will  give. 

The  scale  of  the  instrument  covers  an  arc  of  300 
degrees.  The  instrimient  has  a  control  spring  which 
i!ormally  holds  the  pointer  at  the  center  of  the  scale. 
'i"he  scale  may  be  divided  into  zones  of  different  colors, 
one  indicating  dangerous  operation  or  low  excitation, 
another  indicating  safe  operation,  and  another  indicat- 
ing excessive  excitation.  Each  element  operates  on  the 
induction  principle  and  the  movement  is  light  and  very 
rugged,  so  that  there  is  no  danger  of  damaging  the  in- 
strument under  starting  conditions  or  during  manipula- 
I'on  when  the  current  values  are  liable  to  be  high.  One 
mstrunient  is  rec|uired  for  each  generator. 


Aulotransformer 


FIG.  I— WIRING  DI.\GKAM  OF  THE  STABILITY  INDICATOR 

(In  the  LI.  S.  S.  Tennessee  there  are  three  combina- 
tions for  normal  operation.  One  is  with  two  gener- 
ators and  four  motors  with  twenty-four  pole  windings. 
-Another  is  with  either  generator  and  four  motors  with 
24  pole  windings.  The  third  is  with  either  generator 
and  four  motors  with  36  pole  windings.  With  any  one 
combination  there  is  a  certain  ratio  between  the  im- 
pressed voltage  and  the  line  current  which  must  be 
maintained  for  stable  operation.  In  order  that  the  in- 
strument may  indicate  correctly  under  all  the  above 
combinations,  it  was  necessary  to  supply  an  autotrans- 
former  which  is  connected  to  the  secondary  of  the  volt- 
age transformer  so  that  the  voltage  applied  to  the  in- 
strument could  be  changed  for  each  combination.  The 
shifting  of  taps  on  the  autotransformer  is  accomplished 
by  means  of  auxiliary  switches  which  are  operated  auto- 
matically when  the  main  switching  is  done  to  obtain  the 
above  combinations.  Therefore  no  matter  which  com- 
b'nation  is  in  service,  the  instrument  will  always  in- 
dicate the  correct  value  of  field  excitation  on  the  gener- 
ator for  stable  operation. 


.?/(<im 


W.  B.  FLANDEKS 

Marine  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


THE  main  power  plant  of  the  Tennessee  consists 
of  two  duplicate  steam  turbines  of  i6ocx)  brake 
horse-power  capacity  and  with  a  nominal  full 
speed  of  2075  r.p.m.  They  are  of  the  impulse  and  re- 
rction  double-flow  type  and  are  designed  to  take  steam 
at  250  pounds  gage  pressure  at  the  throttle,  50  degrees 
superheat,  28.5  inch  vacuum.  The  turbines  have  an 
economical  operating  speed  range  from  about  1500  t'j 
2200  r.p.m. 

A  view  of  the  turbine  from  the  generator  end  is 
shown  in  Fig.  i,  and  Fig.  2  shows  a  view  from  the  op- 
posite end,  both  illustrations  showing  the  turbine  on 
the  test  floor,  without  lagging,  and  connected  to  a  water 
brake  instead  of  ihe  generator.  When  installed  in  the 
ship,  the  generator  occupies  the  position  here  taken  by 
the  brake,  being  connected  to  the  turbine  by  means  of  a 
suitable  coupling. 


FIG.   I  —  M.MN   16  000  HORSE-POWER  TURBINE  VIEWED  FROM 
GENERATING  END 

The  turbine  and  generator  rotors  are  each  carried 
en  a  pair  of  babitted  bearings,  the  pedestals  for  the  gen- 
erator bearings  being  separate  castings  secured  directly 
lo  the  seatings.  The  coupling-end  turbine  bearing  is 
carried  by  the  end  of  the  turbine  cylinder,  which  in  turn 
is  supported  on  the  sides  at  the  center  line,  by  "chairs", 
secured  rigidly  to  the  seatings.  The  turbine  bearing  at 
the  opposite  end  is  held  by  a  pedestal  part  of  the  cylin- 
der casting,  resting  on  the  seating  and,  like  the  cylinder 
supports  at  the  opposite  end,  resting  on  the  chairs,  free 
to  slide  endwise  with  the  expansion  or  contraction  of 
the  cylinder.  The  cylinder  as  a  whole  is  prevented 
from  moving  by  being  bolted  rigidly  to  the  inboard 
generator  pedestal. 

High-pressure  steam  is  admitted  to  the  turbine  at 
approximately  the  center.  It  first  passes  through  a 
strainer,  then  through  a  throttle  valve  which  may  be 
opened   or   closed  by  hand  or  which   will   close   auto- 


matically when  the  turbine  reaches  a  predetermined 
speed  above  that  of  normal  full  speed.  The  steam  next 
flows  through  the  "governor  valve"  controlled  by  a  spe- 
cial form  of  governor  which  is  made  to  operate  the  tur- 
bine at  any  desired  speed  from  full  to  about  one-fourth 
full  speed.  Passing  next  through  a  group  of  hand- 
operated  valves,  any  or  all  of  which  may  be  opened,  de- 
pending on  the  load  to  be  carried,  the  steam  enters  the 
nozzle  chambers  of  an  impulse  element.  Here  it  ex- 
pands in  suitable  nozzles,  passes  through  an  impulse 
wheel,  consisting  of  two  moving  and  one  stationary 
row,  and  then  expands  through  a  single  flow  intermedi- 
ate reaction  portion  of  the  unit.  It  then  divides,  one- 
lialf  passing  directly  into  a  low-pressure  reaction  por- 
tion and  the  other  half  through  a  large  oval  shaped  pipe 
over  the  top  of  the  cylinder  to  a  similar  reaction  ele- 
ment on  the  other  end  of  the  machine.  From  each  half 
the  steam  passes  downward  through  an  exhaust  open- 


m 


Mm 


FIG.  2 — MAIN  TURBINE  ON  THE  TEST  FLOOR 

ing  into  the  surface  condenser  located  athwart  ship  di- 
rectly below  the  turbine.  These  exhaust  connections 
are  provided  with  expansion  joints  to  avoid  restriction 
of  the  end  movement  of  the  cylinder  caused  by  expan- 
sion and  contraction. 

Provision  is  made  for  the  admission  to  the  main 
turbine  at  a  suitable  point  of  low  pressure  or  exhaust 
steam  from  the  various  auxiliaries  which  is  not  needed 
for  heating  the  feed  water,  thus  utilizing  the  energy 
available  when  this  steam  is  allowed  to  expand  from  the 
auxiliary  exhaust  pressure  to  that  of  the  vacuum  in  the 
main  condenser.  This  steam  is  admitted  through  a 
Iiand  controlled  valve  and  also  a  butterfly  valve  con- 
trolled by  the  same  overspeed  device  that  actuates  the 
automatic  main  steam  throttle.  There  is  also  a  connec- 
tion from  this  low-pressure  steam  inlet  directly  to  the 
exhaust  chamber  of  the  turbine,  provided  with  an  auto- 
matic   valve   controlled   by   the   steam   governor  valve. 


282 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


This  auxiliary  exhaust  steam  by-pass  valve  opens  when 
the  main  governor  valve  has  closed,  allowing  the  steam 
to  go  direct  to  the  condenser,  instead  of  through  the 
low-pressure  portion  of  the  turbine,  and  thus  preventing 
overspeeding  even  if  there  is  a  sufficient  amount  of  ex- 
haust steam  available  to  run  the  turbine  without  the  use 
of  any  high-pressure  steam.  The  butterfly  valve,  like 
the  automatic  main  throttle,  is  a  final  precaution 
against  overspeeding  and  should  only  function  in  case 
the  normal  speed  control  devices  fail. 

A  feature  of  the  construction  of  the  turbine  rotor 
or  spindle  is  the  total  absence  of  discs  pressed  or  shrunk 
onto  a  shaft.  All  of  the  blade  carrying  elements  are  an 
integral  part  of  the  rotor,  which  is  divided  into  longi- 
tudinal sections  so  that  those  blade  sections  requiring 
it  may  have  a  solid  through  disc  construction  without 
v/eakening  holes.     The  various  sections  are  provided 

Max,  R,  P   M.     Zero  R.  P   M. 

•S4 


of  about  seven  pounds,  is  admitted  to  the  i-unner  cham- 
ber at  the  periphery,  submerging  the  runner  on  each 
side  a  distance  such  that  the  centrifugal  pumping  head 
produced  by  the  runner  balances  the  total  water  pres- 
sure. Thus,  as  both  sides  of  the  runner  are  covered 
by  water  to  a  certain  depth,  no  air  can  pass  mward  in- 
to the  exhaust  chamber  of  the  turbines.  The  elimina- 
tion of  steam  passing  out  from  the  glands  m  noticeable 
quantities,  which  is  usually  a  feature  of  steam  seals, 
is  thus  accomplished  at  practically  all  runnmg  speeds 
and  relieves  the  engine  room  of  what  is  often  a  ver\' 
annoying  feature. 

As  all  of  the  operations  of  maneuvering  are  per- 
formed in  the  central  control  room,  the  speed  of  the 
main  turbine  is  controlled  from  the  same  place.  This 
is  accomplished  by  the  use  of  a  variable  speed  governor, 
which  regulates  the  admission  of  steam  to  the  turbine, 


FIG.  3 — SPEED  AND  POWER  CONTHOLUNG  MECHANISM 


with  deep,  flanged,  pressed  "spigot"  fits,  which  allow 
them  to  be  securely  bolted  after  being  pressed  together, 
the  bolting  being  on  such  a  large  diameter  that  the 
stress  due  to  bending  is  negligible. 

Where  the  turbine  shaft  passes  through  the  ends 
of  the  cylinder  a  combined  steam  and  water  seal  is  pro- 
vided to  prevent  the  inward  passage  of  air.  As  the  tur- 
bine is  double  flow,  for  the  low-pressure  portion,  similar 
glands  are  required  at  each  end.  When  standing  by,  or 
running  at  any  speed  below  one-half  of  full  turbine 
speed,  the  "labyrinth"  type  gland  is  sealed  with  steam, 
but  on  reaching  about  one-half  speed  a  special  gover- 
nor in  connection  with  a  gland  control  valve  turns  the 
steam  off  and  water  on  to  the  outer  portion  of  the 
gland,  which  is  provided  with  a  form  of  paddle  wheel 
or  centrifugal  pump  runner.     The  water  at  a  pressure 


and  by  means  of  a  power  limit  mechanism  in  connection 
with  the  governor-operated  steam  admission  valve. 

The  governor  tends  to  maintain  a  practically  con- 
stant speed,  irrespective  of  the  load,  corresponding  to 
the  setting  of  the  speed  control.  The  power  limit  is 
arranged  so  that  the  steam  flow  may  be  decreased,  ir- 
respective of  the  governor  demands,  but  not  increased 
beyond  the  amount  needed  to  maintain  the  speed  as  de- 
termined by  the  latter.  Fig.  3  is  a  diagram  of  the  speed 
and  power  controlling  mechanisms.  Fig.  3  shows  also 
the  gland  operating  devices,  which  include  a  separate 
flyball  governor  with  super-isochronous  spring,  driven 
by  gearing  from  the  main  speed  governor.  This  gover- 
nor is  set  to  move  at  about  one-half  speed,  operating  a 
steam  relay  which  shifts  the  gland  supply  from  steam 
to  water  and  vice-versa. 


June,  1921 


THE  ELECTRIC  JOURNAL 


283 


The  speed  control  governor,  Fig.  6,  is  in  principle 
a  dead-weight  fly-ball  governor  in  which  variable  speed 
control  is  obtained  by  varying  the  dead  weight.  To  do 
this,  the  effect  of  gravity  in  the  ordinary  construction  is 
replaced    by    the    pressure    from    a    hydraulic    piston 


FIG.  4 — ONE  OF  THE  TWO  SIMILAR  CAST  IRON  LOW  PRESSURE  ENDS  OF 
THE  MAIN  TURBINE 

With  the  reaction  blading  of  the  lower  half  of  the  cylinder, 
against  which  oil  pressure  of  any  desired  amount  from 
zero  to  60  lbs.  per  square  inch  may  be  maintained. 
Thus,  if  the  pressure  is  five  pounds  per  square  inch, 
the  centrifugal  force  due  to  a  turbine  speed  of  about 
400  r.p.m.  will  balance  the  piston,  but  if  the  pressure 
is  increased  to  55  lbs.  the  turbine  speed  necessary  will 
be  about  2100  r.p.m. 

The  oil  pressure  is  regulated  in  the  control  room  by 
the  "governor  control  valve",  Fig.  7.  This  is  a  piston 
opposed  by  a  spring  and  supplied  with  oil  through  a  re- 
lay plunger  and  floating  lever  arrangement.  A  con- 
stant source  of  oil  under  not  less  than  the  maximum 


FIG.   5 — CENTER  SECTION  OF  TURBINE  CYLINDER 

This  section  being  subjected  to  higher  steam  pressures  and 
temperatures  is  made  of  cast  steel  and  is  bolted  between  the 
cast  iron  ends. 

pressure  desired  is  connected  to  the  stand.  On  moving 
one  end  of  the  floating  lever  to  a  desired  position,  by 
means  of  a  worm  gear,  the  plunger  is  first  moved  so  as 
to  regulate  the  supply  of  oil  under  the  piston,  which  in 
turn  moves  until   the  oil   pressure  balances  the  spring 


pressure.  The  floating  lever  automatically  moves  the 
plunger  back  to  its  neutral  position,  or  that  where  the 
oil  passed  by  it  just  equals  the  leakage  from  the  system. 
Thus,  for  any  position  of  the  end  of  the  floating  lever, 
there  is  a  definite  position  of  the  control  piston  and 
compression  of  the  spring, 
with  a  corresponding  oil 
pressure.  The  oil  pressure, 
in  turn,  determines  the 
speed  of  governing,  so  that 
for  every  position  of  the 
control  wheel  the  main  tur- 
bine will  govern  at  the  re- 
lated speed .  A  motor  driven 
vibrator  moves  the  plunger 
up  and  down  continually  at 
about  1 60  times  per  minute. 
This  serves  to  keep  the  oil 
pressure  fluctuating  slight- 
ly, enhancing  the  sensitive- 
ness of  the  control. 

The  governor  operates 
the  main  steam  admission 
valve  through  an  oil  relav 
system  similar  to  that  now  ''=■  ^^^^^  *^°''™°'-  governor 
generally  used  on  the  larger  land  turbines.  Hand-con- 
trolled nozzle  groups  allow  proportioning  of  the  nozzle 
area  to  the  load  to  be  carried,  and  thus  limit  the  de- 
mands on  the  boilers,  as  well  as  permit  a  proper  choice 
of  nozzles  from  the  efficiency  standpoint. 

Exhaust  steam  from  the  auxiliaries  is  admitted  to 
the  low-pressure  end  of  the  main  turbines.     A  by-pass 


FIG.   7 — GOVERNOR  CONTROL  VALVE 

Located  in  the  control  room,  it  regulates  the  oil  pressure 
for  varying  the  dead  weight  of  the  speed  control  governor. 

valve  from  this  inlet  to  the  exhaust  of  the  turbine  is 
opened  either  by  hand  or  automatically  by  the  oil  relay 
system  which  controls  the  main  steam  admission  valve, 
when  this  valve  reaches  its  seat  and  there  is  sufficient 


284 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  0 


exhaust  steam  to  cause  the  turbine  to  continue  to  speed 
up. 

The  turbine  is  started  up  and  shut  down  by  means 
of  a  hand-operated  throttle  valve  in  the  main  steam  line. 
This  valve  is  also  connected  through  a  steam-operated 
trip  gear  to  a  separate  overspeed  governor  carried 
directly  on  the  main  turbine  shaft.  The  same  governor, 
with  a  similar  mechanism,  also  shifts  the  oil  supply  to 
the  speed  control  governor  system  lines,  closing  the 
main  steam  inlet  valve  and  opening  the  auxiliary  ex- 
haust by-pass  valve  described  above.  It  also  causes  the 
closing  of  a  butterfly  valve  in  the  auxiliary  exhaust 
inlet. 

The  bell  crank  connecting  the  main  speed  governor 
to  the  floating  lever  of  the  steam  valve  control,  is  made 
in  two  parts,  held  together  as  one  by  a  suitable  spring. 
A  link  from  the  floating  lever  connection  engages  at  its 
lower  end  with  the  power  limit  in  such  a  manner  as  to 
be  free  always  to  move  downward,  but  only  upward  as 
far  as  the  limit  will  permit.  Thus  the  governor  can 
iilways  move  its  end  of  the  floating  lever  so  as  to  shut 
off  steam,  but  can  only  move  it  in  the  direction  of  ad- 
mitting more  steam  as  determined  by  the  power  limit. 
The  two  parts  of  the  bell  crank  separate,  allowing  the 
governor  to  move  freely,  but  with  the  spring  holding  the 


floating  lever  against  the  restraining  shoulder  of  the 
power  limit. 

This  restraining  mechanism  of  the  power  limit  is 
moved  to  any  position  by  means  of  a  motor-driven 
woiTTi  gear.  At  the  same  time  this  gear  is  moving  the 
limit,  it  revolves  the  transmitter  of  an  electrical  posi- 
tion indicator,  the  receiver  of  which  is  in  the  control 
room.  It  also  operates  a  double  stop  switch,  which 
breaks  the  motor  circuit  when  the  limit  reaches  either 
end  of  its  travel,  but  does  not  prevent  the  motor  being 
operated  in  the  opposite  direction.  The  control  of  this 
limit  is,  of  course,  in  the  control  room,  where  the  opera- 
tor, by  observing  the  positive  indicator,  knows  its  set- 
ling  at  all  times. 

Signal  lamps  disclose  the  relative  positions  of  the 
governor  and  the  limit,  i.e.,  as  to  whether  the  steam  is 
under  the  control  of  the  governor' or  is  being  restrained 
by  the  limit.  A  similar  lamp  signal  indicates  when  the 
main  throttle  is  closed  or  open. 

A  pressure  operated  interlock,  preventing  the  open- 
ing or  closing  of  the  generator  field  switch,  is  connected 
to  the  oil  line  between  the  governor  control  stand  and 
the  governor.  It  is  adjusted  so  as  to  liberate  the  field 
switch  when  the  oil  pressure  is  below  a  certain  amount, 
necessitating  the  setting  of  the  governor  speed  control 
at  a  low  speed  before  maneuvering  can  be  done. 


Til©  bWm  Cont^r-vtw^  of  tli^^  U,  ^,  S,  TouiU)-s:>o^q 


\i.   v..   t.ll  NIW 

Power  Engineering  Dej)t., 

Westinghousc  Electric  &  Mfg.  Company 


THE  electric  propulsion  of  a  ship  involves  the  sup- 
ply of  power  over  a  wide  range  of  speed,  torque, 
and  terminal  voltage  for  the  generator.  In  the 
case  of  the  Tennessee,  this  power  is  supplied  from  al- 
ternating-current generators  to  induction  motors, 
which  are  connected  to  the  propellers.  It  is  necessary 
that  the  combination  of  generators  and  motors  be  con- 
sidered together,  and  that  the  apparatus  be  so  de- 
signed as  to  have  the  proper  characteristics  to  give 
satisfactory  performance  as  a  single  unit. 

Any  alternating-current  generator  at  a  constant 
speed  and  excitation,  will  give  a  terminal  voltage  which 
is  dependent  upon  the  value  of  the  load  which  it  is  car- 
rying, and  also  upon  the  power-factor  of  that  load. 
Assuming  that  the  power-factor  could  be  held  constant, 
there  would  correspond  to  a  fixed  excitation  a  curve 
between  kv-a  and  current,  the  kv-a  starting  at  zero 
and  increasing  with  the  current  up  to  a  maximum 
value,  and  then  decreasing  again  to  zero,  the  termin- 
al voltage  at  the  same  time  starting  at  a  maximum 
and  decreasing  to  zero.  A  family  of  curves  between 
k-v-a  and  current  could  be  drawn,  corresponding  to 
other  values  of  the  power-factor. 

An  induction  motor  at  constant  frequency  ven' 
nearly  follows  the  law  that  for  a  change  in  voltage  the 


torque  developed  will  change  in  the  ratio  of  the  square 
of  the  voltage  variation,  and  that  the  slip,  power-fac- 
tor and  efficiency  will  keep  the  same  values  as  for  the 
original  torque.  Further,  the  efficiency  and  power- 
factor  of  the  motor  at  different  frequencies  will  remain 
the  same  for  equal  torques,  provided  that  such  torques 
correspond  to  equal  fluxes,  or,  in  other  words,  that  the 
impressed  voltage  is  varied  directly  as  the  frequency. 

.Since,  for  any  given  condition  of  load,  the  gener- 
ator voltage  is  dependent  directly  upon  the  excitation, 
it  is  evident  that  proper  control  of  the  excitation  is 
most  important.  If  the  excitation  is  too  low  for  the 
load  to  be  carried,  the  generator  will  drop  the  load. 
If,  on  the  other  hand,  the  excitation  is  maintained  at 
too  high  a  value,  then  the  terminal  voltage  of  the  gen- 
erator will  also  be  too  high,  resulting  in  unnecessary 
iron  losses  in  both  generator  and  motor.  This  latt<;r 
condition,  therefore,  results  in  operation  at  a  reduced 
overall  efficiency. 

The  above  brief  statements  show  at  once  that  the 
rating  of  apparatus  for  a  ship  is  somewhat  indefinite, 
since,  for  a  fixed  load  at  a  given  speed,  the  voltage, 
current,  kv-a,  and  the  power-factor  will  all  change  with 
a  change  in  excitation.  The  rating  is,  therefore,  neces- 
sarily nominal,  unless  it  is  tied  up  with  a  margin  be- 


June,  1921 


THE  ELECTRIC  JOURNAL 


285 


tween  working  torque  and  maximum  torque.  The 
factors  which  determine  the  margin  necessary  in  op- 
eration are  the  condition  of  the  sea",  that  is,  whether 


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FIG.    I — GENERATOR   VOLTAGE   CHARACTERISTIC 

The  voltage,  at  any  speed  is  proportional  to  the  flux 
at  230  amperes  field  current, 
smooth  or  rough,  the  loading  of  the  ship  and  the  setting 
of  the  throttle  to  limit  the  maximum  power  which  can 
be  delivered.     In  general,  the  margin  of  excitation  at 
any  time  must  be  sufficient  to  prevent  the  motors  be- 


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plished  in  practice  through  the  adjustment  of  a  stop 
on  the  throtde  to  limit  its  opening,  and  by  setting  the 
field  current  to  the  proper  value.  This  value  of  field 
current  is  determined  by  means  of  the  indication  on 
the  dial  of  an  instrument  which  shows  the  relative 
value  of  working  torque  to  maximum  torque. 

Inasmuch  as  the  speed  control  of  the  ship  is  ob- 
tained by  variations  in  speed  of  the  turbine  generators, 
which  produce  corresponding  changes  in  generator 
voltage,  it  is  obvious  that  there  can  be  no  fixed  rated 
voltage  or  speed.  The  generator  characteristic  curves 
shown  in  Figs,  i,  2  and  3  are,  therefore,  plotted  against 
what  may  be  called  a  "reference  flux,"  on  the  assump- 
tion that,  with  a  given  flux,  the  generator  voltage  is 
directly  proportional  to  the  speed,  which  is  approxi- 
mately correct.  By  reference  flux  is  meant  the  flux 
corresponding  to  some  arbitrarily  chosen  operating 
point.  The  variation  of  reference  flux  with  current 
on    the  Tennessee  generators    under    the    condition    of 


1 

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riC.  2 — COMBINED  PERFORMANCE  OF  TWO  MOTORS  LOADED  ON 
ONE  GENERATOR 

ing  pulled  out  of  step  by  any  load  within  the  limit  of 
the    throttle    setting   on    the    turbine.     This    Is    accom- 


FIG.   3 — STABILITY   FACTORS,   UNDER   VARIOUS   OPERATING  CONDITIONS 

constant  excitation  at  230  amperes  field  current  is 
shown  in  Fig.  i.  From  a  series  of  such  curves  taken 
in  conjuction  with  the  motor  characteristics,  the  com- 
bined performance  of  two  motors  loaded  on  one  gen- 
erator is  shown  in  Fig.  2  for  several  different  values 
of  field  current.  Fig.  2  gives  the  motor  power- factor, 
efficiency  and  torque,  as  derived  from  test  data,  plotted 
against  current.  In  addition  it  shows  the  generator 
current  plotted  against  propeller  torque  for  a  series  of 
field  amperes  on  the  generator.  The  construction  of 
these  points  is  as  follows : 

At  1500  amperes  per  motor  (corresponding  to 
3000  amperes  per  generator,  since  the  motors  are  in 
parallel),  the  power- factor,  Fig.  2,  is  0.833.  Ii^  Fig- 
I,  a  straight  line  is  drawn  from  the  zero  point  through 
the  point  corresponding  to  3000  amperes  and  100  per- 
cent fluv      ''"his   "3000  ampere  line"   cuts  the  voltage 


286 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


characteristics  for  0.833  power-factor  at  101.5  percent 
rated  flux  and  3060  amperes.  This  point  is  trans- 
ferred to  Fig.  2.  Other  points  derived  m  the  same 
manner  from  Fig.  i  give  the  characteristic  curve  for 
230  amperes  field  current.     The  curves  for  the  other 


FIG.  4 — STATOR  CORE 

field  currents  shown  in  Fig.  2  are  similarly  derived 
from  other  curves  similar  to  Fig.  i  for  the  respective 
field  currents. 

The  propeller  torque  curves  corresponding  to  the 
various  field  currents  in  Fig.  2  are  obtained  from  tlie 
flux  curves  and  the  motor  torque  curve,  remembering 
that  the  torque  relation  varies  as  the  square  of  the 
voltage  change.  Thus,  for  example,  the  moior  torque 
at  100  percent  flux  and  1500  amperes  per  motor  is 
282  000  pounds  feet.  From  the  current  flux  curves 
for  230  amperes  it  is  seen  that  at  3000  ampere  load 
on  the  generator  the  flux  is  1.02  times  normal.  This 
value  squared,  times  the  motor  torque  for  3000  am- 
peres at  100  percent  flux  gives  the  actual  propeller 
torque  obtained  with  230  amperes  field  current  and 
3000  amperes  generator  current,  giving  one  point  on 
the  propeller  torque  curve,  for  230  amperes  field  cur- 
rent. The  other  points  on  these  curves  are  plotted  sim- 
ilarly. 

From  Fig.  2  the  curves  in  Fig.  3  arc  readily  ob- 
tained. The  values  of  K  in  Fig.  3  are  stability  factors, 
that  is  K  equals  the  ratio  between  the  maximum  power 
which  the  generator  can  carry,  and  the  total  power 
required  by  the  ship  at  any  speed.  The  values  for 
K=zzi  are  taken  from  the  peaks  of  the  propeller  torque 
curves,  the  four  peak  points  in  Fig.  2  giving 
four  points  on  the  torque  curve  for  K=i  in  Fig.  3. 
At  any  value  of  field  current,  the  torque  at  1.05  stabili- 
ty factor,  equals  that  at  unity  divided  by  1.05,  etc. 

Similarly  the  ampere  curve  for  K=i  in  Fig.  3  is 
obtained  from  the  peak  points  of  the  propeller  torque 
curves  in  Fig.  2,  the  ampere  curve  for  K=i.oCi  is  ob- 


tained from  the  K=i.oi  torque  points  previously 
plotted  on  the  propeller  torque  curves,  etc.  Likewise 
the  reference  flux  curves  in  Fig.  3  are  obtained  by 
drawing  a  vertical  line  from  the  corresponding  points 
on  the  propeller  torque  curves  in  Fig.  2,  from  which 
the  percent  reference  flux  for  each  field  current  and 
stability  factor  are  read. 

Fig.  3  shows  at  a  glance  the  stability  factor  cor- 
responding to  any  given  excitation  for  any  speed  of 
the  ship,  as  well  as  the  current  and  percent  reference 
flux  corresponding  to  the  same  conditions.  For  any 
given  power,  the  change  in  excitation  can  be  shown 
for  different  values  of  K.  This  has  been  illustrated 
on  Fig.  3.  for  a  speed  of  19  knots. 

GENERATOR   EQUIPMENT   FOR   THE   TENNESSEE 

There  are  two  generators  on  tlie  Tennessee,  each 
having  a  nominal  rating  of  13250  kv-a,  three-phase, 
34.6  cycles,  3270  volts  at  83.4  percent  power-factor, 
and  a  maximum  rating  of  14  850  kv-a,  three-phase,  at 
2195  r.p.m.  The  generators  are  arranged  to  drive 
two  motors  each  over  a  speed  range  of  154S  to  2195 
r.p.m.,  corresponding  to  a  variation  in  ship  speed  from 
16.I  to  21.8  knots.  One  generator  will  handle  four 
motors  between  15  and  16.1  knots,  with  a  change  in 
speed  varj'ing  between  1435  and  1548  r.p.m.  the  motors 
being  operated  with  24  poles.  For  lower  speeds  of  the 
ship  between  10  and  15  knots,  one  generator  handles 
four  motors,  operating  with  36-pole  connection.  The 
speed  range  of  the  generator  under  this  condition  is 
between  the  limits  of  1430  and  2175  r.p.m. 

Tin-  Diincipal  difference  in  the  electrical  design  of 


FIG.  5 — STATOR  CORE  PARTLY  WOUND 

generators  for  ship  propulsion  and  for  ordinary  land 
service  are  the  necessity  of  providing  insulation  to 
withstand  salt  air,  and  the  provision  of  a  greater  de- 
gree of  overload  margin  in  the  field  design  tor  ship 


June,  1 92 1 


THE  ELECTRIC  JOURNAL 


287 


service.  This  overload  margin  must  be  provided  to 
take  care  of  short  time  operating  periods,  sucli  as  are 
encountered  in  turning,  stopping  and  reversing  the 
ship.  The  Tennessee  generators  are  designed  to  with- 
stand safely  a  50  percent  increase  over  their  maximum 
continuous  operating  field  current  for  short  periods. 

Temperature  Rise — The  generators  are  designed 
to  deliver  their  rated  output  vi^ith  a  temperature  per- 
formance in  line  with  normal  land  practice.  Tests 
made  at  zero  power-factor  show  a  rise  by  themo-cou- 
ple  of  53  degrees  C.  at  a  load  of  13  500  kv-a,  36.5  cy- 
cles, 3460  volts,  and  48  degrees  C.  at  the  same  current, 
and  at  10800  kv-a  and  28.8  cycles. 

Mechanical  Designs — The  principal  difference  in 
the  mechanical  design  as  compared  with  land  practice 
is  the  omission  of  the  bedplate,  and  the  addition  of  in- 
let and  outlet  dampers  in  the  air  ducts. 


FIG.  6 — STATOR  COMPLETELY  WOUND  .\ND  CONNECTED 

Stator  Core — The  stator  frame  is  an  iron  casting 
with  inwardly  projecting  ribs.  Into  this  frame  are  as- 
sembled the  segments  of  sheet  steel  which  made  up  the 
core.  The  ventilation  is  arranged  for  air  to  be  passed 
in  openings  in  the  iron  in  an  a.xial  direction,  and  dis- 
charged at  the  center  of  the  machine,  as  shown  in  Fig. 
4- 

Stator  Windings — The  stator  winding  consists  of 
two  conductors  per  slot;  each  conductor  is,  therefore, 
insulated  from  ground  and  from  one  another  with  a 
maximum  factor  of  safety.  Each  conductor  is  made 
up  of  a  number  of  strands,  individually  insulated  with 
mica  tape  to  break  up  eddy  currents.  The  assembled 
strands  are  insulated  on  the  straight  part,  which  is 
buried  in  the  core,  with  mica  folium,  and  on  the  ends 
with  mica  tape.  The  end  windings  are  then  specially 
treated  with  a  considerable  number  of  coats  of  mois- 
ture resisting  varnish  to  insure  protection  against  salt 
m  the  cooling  air.  A  core  in  the  process  of  winding  is 
illustrated  in  Fig.  5     Considerable  care  has  been  taken 


to  brace  the  end  windings  as  securely  as  possible.     The 
finished  stator  winding  is  shown  in  Fig.  6. 

Ventilation — The  fans  on  each  end  of  the  rotor 
supply  the  cooling  air.  The  air  is  drawn  from  a  cham- 
ber under  the  end  bells,  and  passes  through  the  air- 
gap  and  axial  ducts  in  the  rotor  and  stator  to  the  cen- 


FIG.    7 — DAMPER    MOUNTED   ON    STATOR   FRAME 

Dampers  are  provided  in  the  inlet  and  outlet  ducts  to  cut 
oft"  the  air  supply  when  the  ship  is  idle. 

ter  of  the  machine.  From  there,  it  passes  into  tlie 
frame  and  out  into  the  discharge  duct.  Dampers  are 
provided  in  the  inlet  and  outlet  ducts  to  cut  off  the  air 
supply  when  the  ship  is  idle.  Fig.  7  shows  the  inlet 
damper  on  one  end,  and  shows  the  sheet  metal  casing 


FIG.   S — ROTOR   IN   THE  PROCESS   OF   WINDING 

connecting  the  generator  with  the  discharge  duct. 
The  outlet  dampers  are  mounted  above  this  casing,  and 
connect  the  generator  outlet  with  the  discharge  duct 
in  one  limiting  position,  and  in  the  other,  connect  the 
discharge  duct  directly  with  the  engine  room,  at  the 
same  time  closing  off  the  generator  outlet. 

Rotor — The  rotor  is  made  of  one-piece  steel  forg- 


288 


THE  ELECTRIC  JOURNAL 


Yo\.  XYIII,  No.  6 


ing  provided  with  radial  slots  which  carry  the  coils. 
The  windings  are  insulated  throughout  with  mica  or 
other  fire-proof  material.  There  is  no  provision  for 
ventilation  within  the  bod}-,  so  that  there  Is  no  chance 
of  tlie  accumulation  of  salt  deposit  in  the  rotor.  Fig. 
8  illustrates  the  rotor  in  the  process  of  winding. 


Steam  Heater — To  maintain  the  temperature  of 
the  generator  above  that  of  the  surrounding  air  when 
the  generator  is  idle,  steam  heating  coils  are  provided 
in  tlie  end  bell.  This  heater  is  necessary  to  prevent 
precipitation  of  moisture  upon  the  coils  and  other  parts 
of  the  machine  where  it  might  be  objectionable. 


Tivo  HorvD 


leeter 


©i:'  t\v)  iiinUiosliij) 


Tdiuiossod 


i-fc-  - 


C.  B.  MILLS 

Chief    Engineer, 
The  Sperry  Gyroscope  Co. 


IN  a  modem  battleship,  such  as  the  Tennessee,  con- 
structed for  only  one  purpose  and  that  to  defeat 
the  enemy,  it  is  absolutely  essential  that  the  instru- 
ments of  navigation  and  tliose  b}"^  which  the  gun  fire 
is  controlled  and  directed  be  of  the  utmost  accuracy 
and  precision  hmnanly  possible,  as  the  entire  effective- 
ness of  the  ship  and  its  excuse  for  existence  is  nulli- 
fied unless  she  can  hit  the  enemy  ship  aimed  at. 

On  the  rolling  and  heaving  surface  of  the  sea,  a 
fixed  and  stable  gun  platform  is  impossible  and  the 
use  of  telescopic  sights  on  the  gun  is  no  longer  feasi- 
ble at  the  ranges  under  which  engagements  now  take 


FIG.   I — SPERRY  M.ASTER  GYRO  COMP.^SS 

The  two  masters  used  on  the  Tennessee  saw  service  on  two 
United  States  Mine  Layers  in  the  North  Sea  during  the  war. 

place.  The  need  of  a  reliable  means  of  controlling  the 
ship's  batter}^  quickly  and  accurately  from  a  single 
station  has  long  been  realized;  in  fact,  present  day 
methods  of  warfare  have  made  such  control  absolutely 
imperative.  Greatly  increased  battle  ranges,  interfer- 
ence of  smoke,  spray,  and  gases  at  the  guns,  inadequate 
means  of  concentrating  the  fire  under  adverse  condi- 
tions, have  been  the  chief  causes  leading  to  a  centrah- 
zation  of  control.  At  the  same  time,  they  have  been 
determining  factors  in  locating  this  control  aloft. 

To  obtain  maximum  effectiveness  the  battery  must 
be  operated  as  a  single  unit.     To  this  end  there  must 


be  an  accurate  means  of  communicating  to  all  guns  the 
proper  angles  of  elevation  and  train ;  the  guns  must  be 
laid  and  the  turrets  trained  to  tliese  angles ;  and  finally, 
the  whole  battery  must  be  fired  from  the  central  con- 
trol, at  the  proper  instant  as  determined  by  the  officer 
responsible  for  the  firing. 

A  naval  engagement  nowadays  starts  as  soon  as 
the  enemy  is  sighted.  With  the  long  range  turret  guns 
now  in  use,  firing  begins  immediately,  often  at  20  000 
yards  range,  whetlier  the  enemy  ship  is  in  sight  above 
the  turrets'  horizon  or  not.  The  only  requirement  is 
that  it  shall  be  visible  from  one  of  the  fighting  tops.  It 
is  apparent  that  under  such  conditions  the  ordinary 
telescopic  sights  in  the  turret  are  useless,  and  the  ship 
that  has  no  other  method  of  sighting  her  battery, — 


This   repeater  is   contrullcd  by  the   master  g>-ro  compass, 
through  the  panels  shown  in  Fig.  3. 

in  other  words,  one  not  fitted  with  a  central  control 
aloft — is  likely  to  be  sunk  long  before  she  can  close  to 
a  range- where  her  guns  can  be  used  effectively. 

It  was  to  over-come  these  handicaps  that  the 
Sperrj^  Fire  Control  System  was  devised  in  collabora- 
tion with  the  ordnance  officers  of  the  Navy,  and  is  be- 
ing fitted  to  all  of  our  firstline  battleships. 

This  system  makes  possible  the  control  of  all  guns 
from  the  fighting  top  and  the  guns  are  trained,  laid, 
and  fired  with  the  greatest  accuracy  under  absolute 
control  and  with  that  co-ordination  which  insures  the 
greatest  damage  to  the  enemy. 

It  will  be  obvious  that  however  large  a  ship,  it  is 
still  but  a  floating  speck  on  the  ocean,  and  that  to  fol- 


June,  1921 


THE  ELECTRIC  JOURNAL 


289 


low  the  enemy  ship  and  maintain  its  proper  bearing 
thereto  a  fixed  base  is  absolutely  essential.  This  fixed 
base  line  is  provided  by  the  spinning  wheel  of  a  gyro- 
scopic compass  which  is  located  in  the  bowels  of  the 
ship,  and  which  is  not  influenced  in  the  slightest  degree 
by  the  rolling  and  pitching  of  the  ship,  by  magnetic  in- 


FIG.  3 — RELAY  SVNCHKONIZERS  AND  REPEATER  PANELS 

For    the     duplex     gjro     compass     equipment     aboard     the 
Tennessee. 

fluences,  firing  of  salvos  or  any  of  the  shocks,  concus- 
sion, and  tumult  incidental  to  naval  engagements.  This 
spinning  wheel  is  maintained  in  space,  rigidly  obeying 
nature's  laws  with  its  axis  of  spin  pointing  to  the  true 
north  and  lying  in  the  geographic  meridian. 

This  so-called  Master  Compass  rnay  be  called  the 


master  brain  of  the  whole  ship's  intricate  organization 
for  navigation  and  fighting  purposes,  as  on  its  integrity 
of  action  depends  the  entire  effectiveness  of  gun  firing. 
Continuous  electrical  impulses,  synchronizing  the  re- 
peaters with  its  own  indicators,  are  sent  out  from  it 
to  all  of  the  delicate  ordnance  instruments  used  in  the 
various  functions  of  training  and  laying  of  the  guns, 
and  to  the  various  instruments  by  which  torpedoes  are 
aimed  and  fired.  From  this  master  compass  emanate 
also  circuits  or  nerve  lines  to  the  compass  repeaters 
used  for  steering  and  taking  bearings  and  the  general 
navigation  of  the  ship. 

In  the  first-line  battleships  such  as  the  Tennessee, 
these  master  compass  equipments  are  always  installed 
in  duplicate,  and  under  service  conditions  both  are  kept 
running  continuously,  so  that  in  case  of  a  break-down 
of  any  of  the  circuits  due  to  gun  fire,  all  of  the  com- 
pass repeaters  and  ordnance  apparatus  electrically  con- 
nected thereto  may  be  shifted  over  instantly  to  the  re- 
maining compass.  This  great  responsibility  resting  on 
a  small  instrument  has  resulted  in  the  development  of 
a  piece  of  mechanism  which  exhibits  a  refinement  of 
workmanship,  design,  detail,  and  dependability  plac- 
ing it  in  a  class  entirely  by  itself. 

It  is  a  re-freshing  thought,  and  one  which  is  of 
supreme  interest  to  the  United  States  Navy,  that  this 
apparatus,  mainly  responsible  for  the  fighting  ship  hit- 
ting the  target,  was  the  product  of  one  of  this  country's 
well-known  engineers  and  inventors  and  the  best  evi- 
dence of  its  undoubted  fulfillment  of  purpose  is  the 
fact  that  of  the  United  States  first  line  of  fighting 
ships,  all  use  the  gyroscopic  compass  as  the  foundation 
of  their  navigating  and  fire  control  equipment. 


THE 
ELECTRIC 
JOURNAL 


©FEIEATEM^   P^TA 


FOE  C0IMVEET11MG 


^Kr 


JUNE 

1921 


Installation  and  Maintenance  of  Automatic  Substations 


Where  the  high-tension  voUage  justifies  it,  a  completely 
new  automatic  substation,  that  is,  one  involving  new  appara- 
tus throughout  may  be  installed  economically  by  making  the 
arrangement  include  outdoor  high-tension  switchgear  and 
transformers  ;  the  building  being  made  to  house  only  the  ro- 
tating apparatus  and  the  switching  equipment  for  the  low-ten- 
sion side  of  the  power  transformers  and  the  direct-current  side 
of  the  machines.  In  single  unit  stations  of  300  to  1500  kw  ca- 
pacity, the  floor  space  required  is  relatively  small  in  compari- 
son with  the  ordinary  manually-operated  substations  of  equal 
capacity.  Since  outdoor  high-tension  apparatus  is  used,  head- 
room for  removing  coils  from  the  transformers  is  not  requir- 
ed. The  height  of  the  building  need  then  be  only  such  as  to 
permit  of  ready  dis-assembling  of  the  converting  apparatus,  in 
case  it  becomes  necessary  to  make  repairs.  It  is  safe  to  say  that 
this  type  of  semi-outdoor  construction  eliminates  from  25  to 
50  percent  of  the  building  cost. 

It  has  been  argued  that  the  alternating-current  starting 
panel  should  be  located  between  the  transformers  and  the  con- 
verter in  order  to  economize  in  the  cables  connecting  the  trans- 
formers and  the  converter.  However,  the  simplification  of  the 
control  wiring  and  conduit  layout  made  possible  by  assembling 
the  panels  in  a  composite  group  goes  far  toward  offsetting  any 
added  cost  of  cable  required  for  the  main  wiring  between  the 


panels,  transformers  and  machines.  Wiring  diagrams  and  lay- 
outs showing  the  arrangement  of  conduits  carrying  the  control 
wiring  between  various  points  in  the  substation,  have  been 
worked  out  for  not  more  than  si.x  control  wires  in  any  one  con- 
duit. The  control  circuits  are  then  wired  with  standard  six  con- 
ductor, rubber  insulated,  braid  covered,  flameproof  cable. 
This  permits  the  use  of  a  standard  six-hole  porcelain  covered 
terminal  condulet,  which  makes  it  possible  to  bring  the  control 
wiring  up  to  the  terminals  on  the  panels  without  cross  wiring. 
The  multiple  conductor  cable  being  coded,  it  is  then  possible, 
by  lettering  the  conduits,  to  pick  up  the  code  at  one  end  and 
immediately  pick  it  up  at  the  other,  to  trace  any  circuit.  In  the 
newer  developments,  sufficient  space  has  been  left  and  the 
panels  used  are  large  enough  so  that  the  wiring  on  the  back  of 
the  panels  is  not  crowded,  thus  making  it  possible  to  trace 
readily  any  circuit  in  the  substation.  This  is  of  great  impor- 
tance, especially  in  starting  up  a  new  station,  where  it  is  ne- 
cessary to  check  over  the  wiring  to  see  that  all  circuits  are  in 
the  proper  condition.  Also  in  locating  any  fault  in  the  substa- 
tion while  in  operation,  this  method  of  wiring  proves  of 
great  benefit. 

CONDUITS 

For  the  small  control  wiring,  it  is  common  practice  to  use 
one    inch    conduit    with    standard    fittings.     Conduits    for    the 


290 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  6 


main  power  cables  are  to  be  chosen  only  after  taking  into  con- 
sideration their  location,  that  is,  whether  the  conduits  carry- 
ing them  are  to  be  run  in  the  open,  or  buried  in  the  earth  or 
concrete  floors.  Metal  conduits,  when  properly  installed  and 
protected  against  corrosion,  have  proven  very  satisfactory.  An- 
other good  method  of  installing  conduits  underground  is  to 
use  the  standard  fibre  duct  encased  in  concrete.  Even  should 
the  fibre  duct  be  destroyed  by  the  action  of  moisture,  the  duct 
is  left  more  or  less  intact  in  the  form  of  the  concrete  shell. 
One  of  the  most  successful  conduits  used,  both  with  lead  cover- 
ed and  other  cables,  is  the  ordinary  tile  duct  laid  in  concrete. 
Lead  covered  cable,  when  properly  installed  and  mechani- 
cally protected,  makes  up  an  excellent  installation ;  however, 
in  case  the  cable  is  damaged  by  handling,  it  sometimes  happens 
that  breakdowns  of  insulation  occur  and  circuits  thus  set  up 
between  adjacent  cables  have  resulted  in  cpnsiderable  damage. 
It  is  the  opinion  of  a  number  of  companies  that,  for  interior 
work  where  there  is  little  or  no  moisture,  the  cost  together 
with  the  installation  expense  of  lead  covered  cable  is  not  justi- 
fied. In  their  opinion,  the  rubber  insulated,  flameproof,  braid 
covered,  cable  is  superior  for  this  work.  This  type  of  cable  al- 
so has  an  advantage  in  that  it  is  more  conveniently  handled. 
Where  leadcovered  cable  is  used,  care  should  be  exercised  in 
separating  cables  between  which  dangerous  circuits  may  be  set 
up  due  to  failures  of  insulation,  resulting  from  possible  mechan- 
ical damage  to  the  cable  sheath  and  the  insulation. 


Very  often  new  automatic  switching  equipment  can  be  in- 
stalled in  present  manually-operated  substations  by  simply  ar- 
ranging the  automatic  panels  to  parallel  with  those  of  the  pre- 
sent manually-controlled  board.  This,  of  course,  is  dependent 
wholly  upon  whether  or  not  there  is  sufficient  floor  space. 
Often  it  is  necessary  to  remove  the  manual  switching  equip- 
ment in  order  to  make  space  for  the  new  apparatus,  in  which 
case  many  of  the  old  conduits  may  be  utilized.  It  is  always 
necessary,  however,  to  install  a  very  considerable  amount  of 
control  wiring  and  this  necessitates  opening  the  floors  to  per- 
mit laying  of  conduits.  It  is  not  often  that  new  conduit  is 
required  for  the  main  power  cables;  however,  if  this  is  the  case, 
it  is  generally  more  convenient  and  results  in  a  much  better 
installation  if  the  old  floor  is  removed  and  the  conduits  placed 
in  position  before  the  new  floor  is  put  down. 

OPEBATION 

If  the  men  who  are  to  have  the  care  of  the  substations  are 
permitted  to  assist  in  the  installation  of  the  apparatus,  it  will 
obviously  be  of  material  benefit  to  them  later  in  their  operating 
duties.  Once  complete,  the  installation  should  be  thoroughly 
inspected  to  see  that  all  main  wiring  and  control  connections 


are  properly  made.  It  is  preferable  to  use  lock  washers  on  all 
control  wiring  studs.  All  of  the  auxiliary  contacts  on  the  main 
contactor  switches  and  the  control  relays  should  be  inspected 
to  make  certain  that  the  contacts  are  clean  and  contact  pres- 
sures sufficient.  Contactors  operated  with  alternating  current 
should  be  so  adjusted  as  to  prevent  excessive  vibration  and 
noise.  Cornplete  inspection  will  prevent  the  unnecessary  shut- 
downs, which  always  follow  if  this  procedure  is  neglected. 

INSPECTION 

It  is  often  said  that  even  a  wheelbarrow  needs  a  certain 
amount  of  attention  to  keep  it  in  good  operating  condition.  The 
mere  fact  that  a  substation  is  made  automatic  does  not  mean 
that  it  will  continue  to  function  automatically  without  proper 
attention.  By  proper  attention  is  meant  periodic,  thorough  and 
intelligent  inspection.  A  man  may  visit  a  substation  every  day 
and  find  it  operating  each  time.  For  this  reason  he  may  feel 
satisfied  that  everything  is  in  good  condition.  Often  this  is 
not  the  case,  for  it  may  be  that  the  station  is  still  operating  in 
spite  of  some  slight  misadjustment.  Sooner  or  later  this  con- 
dition is  apt  to  cause  a  shutdown,  whereas,  if  corrected  at  the 
proper  inspection  period,  the  failure  would  have  been  prevent- 
ed. It  is,  therefore,  of  prime  importance  that  the  inspector  be 
thorough  and  systematic  in  his  care  and  maintenance  of  the 
equipment.  A  complete  inspection  once  every  other  week  or 
once  each  month  is  far  better  than  a  daily  visit,  solely  for  the 
purpose  of  learning  whether  or  not  the  station  is  still  in  opera- 
tion. The  manufacturers  are  doing  everything  possible  and 
adopting  every  improvement  that  will  make  the  equipment  as 
nearly  as  possible  fault-proof;  but  only  with  the  hearty  co-oper- 
ation of  the  operators  can  they  hope  to  produce  apparatus  that 
will  give  the  superior  service,  which  is  to  be  obtained  from 
substations  automatically  controlled. 

In  a  number  of  cases  automatic  equipments  have  been  in- 
stalled where  they  were  the  first  of  the  kind  to  be  put  into 
operation  for  a  particular  service.  In  so  far  as  possible,  the 
manufacturer  has  made  every  effort  to  include,  in  the  scheme 
of  control,  every  protection  and  refinement  of  operation  known 
to  the  art ;  however,  conditions  not  anticipated  may  arise.  A 
frank  discussion  of  any  of  these  points  will  prove  very  benefi- 
licial  to  both  the  manufacturer  and  the  user.  The  success  of 
automatic  switching  in  any  application  is  dependent  upon  the 
operator  as  well  as  the  manufacturer.  Close  co-operation  be- 
tween all  concerned,  combined  with  proper  care  and  maintain- 
ance  not  only  of  the  switching  equipment,  but  of  the  appara- 
tus as  a  whole,  are  the  elements  which  assure  satisfaction. 

The  success  and  increasing  popularity  of  automatic  sub- 
station apparatus  is  shown  by  the  fact  that  by  far  the  greater 
percentage  of  new  stations  installed  within  the  past  few  years 
are  of  this  type.  C.  A.  butcher 


Our  subscribers  are  invited  to  use  this  depai^ment  as  a 
means  of  securing  authentic  information  ( 
mechanical  subjects.  Questions  concerning  general  engineer- 
ing theory  or  practice  and  questions  regarding  apparatus  or 
materials  desired  for  particular  ne?ds  will  be  answered. 
Specific  data  regarding  design  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self-addressed.  stamped  en- 
velope should  accompany  each  query.  All  data  necessary  for 
a  complete  underst..nding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
as  the  necessary  information  is  available;  however,  as  each 
queston  is  answered  by  an  expert  and  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


€> 


1986 — Ratio  of  Field  Turns  and  Ar- 
mature Turns — Can  you  give  me  the 
general  relationship  between  the  num- 
ber of  turns  and  size  of  wire  on  the 
armature  and  the  nuinber  of  turns  and 
size  of  wire  in  the  fields  of  shunt 
wound  motors  for  a  given  speed  and 
horse-power?  (b)  The  same  relation 
between  the  armature  and  field  wind- 
ings of  a  series  motor  tor  any  given 
speed  and  horse-power?  (c)  The  same 
relation  between  the  armature  and 
field  windings  (shunt,  series  and  com- 
mutatingpole)  on  compound  and  com- 
pound-commutatingpole  motors  for 
any  desired  speed  and  horse-power? 
D.  E.  c.  (pa.) 

On  constant  speed  motors,  from  5  to 
15  hp,  the  armature  ampere-turns  will 
average  about  75  percent  of  the  shunt 
and    series    ampere    turns.     On    larger 


motors  the  armature  ampere-turns  may 
reach  95  percent  of  the  shunt  and  series 
ampere-turns.  On  totally  enclosed 
motors,  the  ratio  of  armature  ampere- 
turns  to  shunt  and  series  is  smaller  than 
for  constant  speed  open  motors.  The 
current  densitj'  in  the  shunt  field  is 
about  50  percent  of  the  current  density 
in  the  armature,  while  the  current  den- 
sity in  the  series  field  is  about  40  percent 
and  in  the  auxiliary  field  35  percent  of 
the  armature  density.  On  a  series  motor 
the  armature  ampere-turns  may  be  a 
slightly  smaller  percent  of  the  field  am- 
pere-turns than  in  a  shunt  motor.  The 
current  density  in  the  series  field  is 
about  35  percent  of  armature  density. 

w.  K.   H. 

1987 — Transformer  R-^tio — Is  there 
any  simple  method  of  determining 
whether    any    high-tension    coil    of    a 


single-phase  transformer  is  reversed 
when  the  ratio  is  so  great  that  a 
suitable  ratio  check  cannot  be  made 
with  the  available  voltage  and  volt- 
meters at  hand,  as  in  the  case  of 
transformers  of  the  type  used  on 
furnace  work,  stepping  down  from 
about  (x>  000  to  60  volts. 

C.   S.    (QUEBEC) 

Where  no  special  apparatus  is  avail- 
able, the  most  convenient  method  to  de- 
termine if  any  high-voltage  coil  is  re- 
versed, is  to  connect  a  suitable  low  volt- 
age across  the  high-voltage  winding. 
With  one  lead  of  a  voltmeter  perman- 
ently connected  to  one  of  the  coils, 
measure  the  increase  in  voltage  when 
moving  the  other  voltmeter  lead  from 
one  coil  to  the  next.  In  case  one  coil  is 
reversed  a  decrease  in  voltage  wc-ld  be 
observed  when  passing  this  coil.       H.  f. 


The  Electric  Journal 


Vol.  XVII 


July.  1921 


No.  7 


When  the  Standards  of  the  A.  I.  E. 
Stray  Losses       E.  were  revised  in  1913-14,  consider- 
in  able  test  information  was  presented 
Converters         to  the  Standards  Committee  showing 
the  magnitude  of  stray  losses  in  al- 
ternating-current generators  and  motors,  and  definite 
rules    were    adopted    governing  the    inclusion  of  stray 
losses     in     the     conventional     efficiency.      No     data, 
however,    was    available    concerning    stray    losses    in 
synchronous    converters   and  the    Standards  of  the  In- 
stitute have  never  specified  the  magnitude  of  the  strav 
losses  nor  included  them  in  the  conventional  efficiency 
for  this  class  of  machinery. 

During  the  past  few  years  the  effect  of  stray  loss- 
es on  the  efficiency  of  large  60  cycle  booster  converters 
has  been  questioned  in  several  instances  on  account  of 
low  efficiencies  obtained  by  input-output  tests  made  af- 
ter installation.  More  recently  the  booster  converter 
has  been  charged  with  low  efficiency  as  compared  with 
the  simple  converter  without  booster,  presumably  be- 
cause of  increased  stray  losses. 

On  account  of  these  unsettled  questions  the  infor- 
mation contained  in  Mr.  Hague's  article  on  "Stray 
Losses  in  Synchronous  Converters"  is  timely  and  in- 
structive. Such  tests  as  he  describes  are  difficult  to 
make,  but  the  care  as  to  details  in  this  case  has  made 
possible  results  that  are  unusually  consistent.  Tests  of 
this  character  are  strictly  laboratory  tests,  are  expen- 
sive (costing  several  thousand  dollars  in  the  case  of  a 
large  unit),  tie  up  considerable  equipment  and  are  jus- 
tified only  when  the  results  are  generally  applicable. 

Mr.  Hague's  curves  show  that  the  stray  losses  for 
the  several  voltage  conditions,  and  the  same  load,  do 
not  differ  greatly.  This  small  variation  disposes  of 
the  supposition  that  the  efficiency  of  the  booster  con- 
verter is  much  lower  than  that  of  the  simple  converter 
because  of  greatly  increased  load  losses  when  the 
booster  is  excited. 

Another  interesting  point  is  the  effect  of  low  pow- 
er-factor operation  on  the  stray  losses  and  on  the 
efficiency.  The  tests  show  a  greater  stray  loss  in  the 
smiple  converter,  with  a  variation  in  power-factor  suf- 
ficient to  obtain  a  five  percent  change  in  voltage, 
than  in  a  booster  converter  designed  to  give  a  twelve 
percent  variation  in  voltage. 

An  important  fact  brought  out  is  the  large  varia- 
tion in  the  stray  losses  with  greater  loads  than  normal, 
this  IS,  of  course,  well  known  and  characteristic  of 
stray  losses  generally  that  are  dependent  on  current. 
L  nder  all  voltage  conditions,  the  stray  losses  increase 
about  50  percent  with  a  25  percent  increase  in  load 
above  rated  load.  While  the  conventional  efficiency 
contmues  to  mcrease  at  loads  in  excess  of  rated  the 
actual  efficiency  is  maximum  at  rated  load  and  falls  off 
apprecir   'y  at  larger  loads.     The   converter  used   for 


these  tests  was  designed  for  nominal  and  overl.xid 
rating.  When  converters  are  designed  for  the  single 
rating  (without  overload)  the  copper  and  brush  cur- 
rent densities  cannot  be  increased  appreciably  above 
those  that  ha\e  been  employed  at  the  nominal  continu- 
ous rating  in  the  older  designs  without  a  real  sacrifice 
m  the  true  efficiency.  p.  D.  Newbury 


Power 
Transni:ss  o.^ 


No  matter  how  simple  the  problem, 
any  transmission  system  is  more  or 
less  complex  in  that  it  must  neces- 
sarily include  step-up  and  step-down  transformers 
and  secondary  distribution  systems  besides  the  rela- 
tively simple  transmission  line  itself.  Each  of  these 
component  parts  has  its  own  individual  effect  upon  the 
regulation,  power-factor,  and  transmission  efficiency. 
This  being  the  case,  the  process  of  calculation  is  neces- 
sarily complicated  if  the  problem  is  to  be  solved  so  as 
to  point  out  the  most  economical  case.  The  usual 
method  is  to  rely  upon  the  experience  of  the  indivi- 
dual engineer,  in  making  approximations  for  a  com- 
plete solution.  To  determine  the  most  economical 
combination  of  the  numerous  factors  involved  it  is 
usually  necessary  to  make  several  complete  solutions 
based  on  different  assumptions  and  compare  the  cost  of 
each  so  that  any  means  used  to  simplify  the  calcula- 
tions without  sacrificing  accuracy  are  quite  desirable. 

Simplified  methods  of  making  such  comi)utations 
have  recently  been  worked  out  by  Messrs.  Evans  and 
Sels,  and  the  first  of  several  articles,  which  cover  the 
best  of  the  present  day  methods  of  calculations  for 
transmission  problems  in  their  entirety,  appears  in  this 
issue.  While  these  computations  may  appear  compli- 
cated, they  work  out  quite  simply  and  possess  several 
advantages  over  more  approximate  methods.  The 
methods  need  not  be  strictly  mathematical  but  can  be 
applied  graphically.  They  provide  quite  a  simplifica- 
tion, as  they  treat  a  given  transmission  problem  as  a 
network,  deriving  general  circuit  constants  for  the 
whole.  In  general  these  constants  will  remain  un- 
changed and  are  exact  for  any  operating  condition  and 
may  be  used  either  mathematically  or  graphically  in 
solving  different  load  conditions. 

The  articles  are  general  but,  whenever  possible, 
simplifications  have  been  pointed  out  which  will  in- 
volve little  approximation.  When  the  computations  are 
ma<Ie  in  an  orderly  manner  according  to  some  stand- 
ardized form,  quite  a  saving  in  time  is  obtained  with- 
out any  serious  approximations,  as  the  general  form- 
ulas for  the  constants  are  quite  exact  and  in  no  cas,e 
involve  the  difference  of  two  large  quantities.  This 
fact  enables  anyone  to  follow  the  methods  outlined 
easily  and  to  obtain  an  economical  as  well  as  accurate 
solution  of  any  problem.  p.  C.  Hankf.r 


Stray  Lessors  m  oiy-Cych  SyiUDhfOBOTis  liooster 


Determinni: 


yy  {[\')iil-C)i[i,v[>.  'Tosts 


F.  T.  HACLE 

Power  Engineering  Dept., 

Westinghouse  Electric  &  Mfg.  Company 


THE  Stray  losses  in  synchronous  converters  have 
never  received  as  much  consideration  as  the 
stray  losses  in  other  sources  of  direct-current 
power  supply,  due  to  theoretical  considerations  and  ac- 
tual tests  which  show  these  stray  losses  to  be  quite  low- 
in  comparison  with  those  in  other  forms  of  conversion 
apparatus.  The  statement  has  recently  been  made 
that  the  stray  losses  in  the  booster  type  converter  are 
materially  higher  than  the  stray  losses  in  the  simple 
converter,  the  difference  in  efficiency  being  claimed  to 
be  as  much  as  two  or  three  percent.  The  actual  de- 
termination of  operating  efficiency  and  stray  losses 
under  various  conditions  of  operation,  by  means  of 
laboratory  input-output  tests,  appears  to  be  es- 
sential at  infrequent  intervals  in  order  to  direct  atten- 
tion  to  and   maintain   the  true   relative  status  of    the 


FIG.    I — INPUT-OUTPUT  EFFICIENCY  TEST 

On  6000  ampere,  290—260—230  vok,  60  cycle  synchronous 
booster  converter. 

losses  in  the  various  types  of  synchronous  converters. 
The  stray  losses  of  a  6000  ampere,  60  cycle,  syn- 
chronous booster  converter  were  determined  by  taking 
the  difference-  between  the  efficiency  by  tlie  separate 
loss  method  and  the  efficiency  by  laboratory  input- 
output  tests.  The  machine  used  was  a  6000  ampere, 
60  cycle,  260  volt,  booster  converter  having  a  voltage 
range  of  230  to  290  volts.  The  unit  is  large  enough 
to  be  typical  of  those  used  in  Edison  service  without 
being  too  large  for  careful  factory  testing.  The 
input-output  test  methods  used,  while  not  new,  com- 
prised all  of  the  details  and  refinements  in  equipment, 
methods  and  personnel  that  have  been  found  to  be  es- 
sential in  tests  of  this  character.  The  alternating-cur- 
rent power  was  measured  by  three  single-phase  watt- 
meters and  also  by  one  polyphase  wattmeter  while  the 
direct-current  power  was  measured  by  two  sets  of  di- 


rect-current volt-meters  and  ammeters  with  independ- 
ent shunts.  A  trained  force  of  meter  readers  was  used, 
and  all  meters  were  thoroughly  shielded.  Four  groups 
of  15  readings  each  were  taken  for  each  load,  each 
group  with  different  meter  positions,  and  different  me- 
ter readers ;  special  precautions  were  taken  to  avoid 
including  any  readings  during  which  change  of  load 
occurred.  Tests  of  this  character  are  strictly  labora- 
tory tests,  costing  from  one  to  two  dollars  per  machine 
kw  in  addition  to  tying  up  much  testing  equipment. 
Although  not  feasible  on  commercial  circuits,  labora- 


TABLE    I — EFFICIENCIES 
VARIOUS  LOADS 

AND    PERCENT    STRAY    LOSSES    FOR 
AT  UNITY  POWER-FACTOli 

Load   in  Amperes 

Load    in    Percent 

3000 
50 

4500 
75 

6000 
100 

7500 
125 

260  Volts,  No  Buck  or  Boost                                     | 

1 
Separate  Loss  Efficiency. .  .      94.25           95.40 
Input-Output  Efficiency ...  1      93.85           94.65 

Percent  Stray   Loss 0.40     1       0.75 

95.75 
94.95 

0.80     1 

1 

95.80 
94.55 

1.25 

230  Volts.  Bucking  30  Volts                                       | 

Separate  Loss  Efficiency. .  .1     93.45           94.70 
Input-Output  Efficiency.  . ..      93.30           94.25 

Percent   Stray   Loss 0.15             0.45 

95.25 
94.55 

0.70 

95.35 
94.25 



1.10 

290  Volts,  Boosting  30  Volts 

Separate  Loss  Efficiency. .  .[     93.80           95.10 
Input-Output  Efficiency ... ,      93.40           94.30 

Percent   Stray   Loss 0.40             0.80 

95.55 
94.60 



0.95 

95.65 
94.35 

1.30 

260  Volts,   30  Percent  Full  Load   Lead 

ng  Wattle 

as 

Separate  Loss  Efficiency. .  .      93.70           95.10 
Input-Output  Efficiency.  .  .        93.20           94.05 

Percent   Stray    Loss j        0.50             1.05 

95.60 
94.30 



1.30 

95.70 
94.10 



1.60 

lor}-  input-output  tests  are  justified  on  the  manufac- 
turer's part  when  they  represent  the  only  method 
whereby  comparative  data  can  be  obtained  on  certain 
operating  conditions. 

Input-output  tests  at  100  percent  power-factor  on 
converter  collector  rings  were  made  at  50,  75,  100  and 
125  percent  loads  for  the  following  four  operating 
conditions : — 

i^No  buck  or  boost  260  volts 

2-^Boosting  .-50  volts  to  290  volts 

3 — Bucking  30  volts  to  230  volts 

4 No  buck  or  boost,  with  30  percent  of  full  load  leading 

wattless  current  at  the  converted  terminals. 

The  Stray  losses  may  be  summarized  for  these 
four  conditions  of  operation  as  shown  in  Table  II. 

The  magnitude  of  the  individual  losses  at  full 
load  for  each  of  the  above  conditions  of  operation 
are  shown  in  Table  III.     In  all  segregations  of  losses 


July,   1921 


THE    ELECTRIC   JOURNAL 


the  individual  losses  are  expressed  in  percentage  of  the 
converter  input. 

With  accurate  data  on  the  magnitude  of  stray 
losses  in  a  converter  armature  when  working  at  maxi- 
mum boost  voltage  and  when  working  ai  30  percent 
full  load  wattless  current,  it  is  possible  to  mal<e  an  ac- 
curate efficiency  comparison  between  the  booster 
type  converter  and  the  simple  converter  whose  voltage 
range  is  obtained  by  drawing  wattless  currems  through 

TABLE    II— SUMMARIZED    STRAY    LOSSES    EXPRESSED    IN 
PERCENT 


Percent  Doad 

.0 

Mid-Voltage 

Bucking  30  Volts 

0.40 

Boosting  30  Volts 

30  Percent  Full  Load  Watt- 

0.40 

75 
0.75 
0.45 
0.80 

100 
0.80 
0.70 
0.95 

125 
1.25 
1.10 
1.30 

1.05 

1.30      1 

1.60 

an  external  reactance.     This  comparison  is  not,  how- 
ever,    on    machines     designed    for    the    same    voltage 
range,  the  booster  type  having  the  usual  twelve  per- 
cent range,  while  the  reactance  control  unit  has  a  five 
percent  range  corresponding    to  30    percent    full    load 
wattless  current  in  the  converter  armature.     The  stray 
losses    as    determined    with  30    percent  wattless    cur- 
rent in  the  booster  type  unit  must  be  modified  by  sub- 
tracting the  stray  loss  in  the  booster  itself.     The  "boost- 
er is  merely  an  alternating-current  generator  of  high 
standard     performance    characteristics,    having    about 
three  percent  reactance,  and    its   load   loss,    like   other 
60  cycle  generators,  should  be  0.7  percent  of  its  rating. 
In  terms  of  the   converter   kw  its  load   loss   would   be 
0.7    percent    X    0.12    percent    =    0.084    percent.      It 
should  be  fair  to  assume  o.io  percent  as  a  maximum 
value  for  this  booster  stray  loss  reducing  the  stray  loss 
of  the  reactance  control  unit  from  1.3  percent  toi.2  per- 
cent.    A  comparison  of  the  segregated  losses  and  effi- 
ciencies at  full  load  would  then  be  as  shown  in  Table  IV. 
TABLE  III-PERCENTAGES  OF  INDIVIDUAL  LOSSES 


Converter  Output  Kw. 

Machine  Element 

Friction  &-  Windage 
Brush   Friction 
Rotary  Shunt  Field 
Booster  Shunt  Field 
A.  C.  Brush  CR 
Series  Com.Wdg  C'R 
Rotary  Core  Loss 
Booster  Core  Loss 
Rotary  Arm.  C=R 
Booster  Arm.  C'R 
D.  C.  Brush  C=R 
Stray  Loss 

Total  Percent  Loss 
Full  Load  Efficiency 


3^ 
>Q 


0.86 
0.61 
0.22 
0.00 
0.25 
0.23 
0.83 
0.00 
0.52 
0.23 
0.49 
0.80 


m 


5.0s 
94-95 


0.97 
0.69 
0.20 
0.10 
0.28 
0.26 
0.73 
0.21 
0.5s 

0.21 
0.55 
0.70 

5-45 
94SS 


>  S 


0.77 
0-54 
0.28 
0.08 
0.22 
0.20 
0.93 
0.16 
0-59 
0.26 
0.44 
0.95 


540 
94.60 


0.86 
0.61 
0.25 
0.00 
0.25 
0.23 
0.83 
0.00 
0.64 
0.26 
0.49 
1-30 


570 
9430 


293 

magnitude  of  the  stray  losses  would  be  materially  less. 
The  stray  loss  of  0.80  percent  at  mid  voltage,  0.70 
percent  at  maximuin  buck  and  0.95  percent  at  maxi- 
mum boost  further  emphasizes  that  the  60  cycle 
booster  converter  obtains  its  wide  flexibility  in  voltage 
range  and  other  desirable  operating  characteristic 
with  no  sacrifice  in  economy  of  operation.     The  dis- 


FIG.  2— EFFICIENCY  TESTS  AT  260  VOLTS 

proportionate  increase  in  stray  losses  above  full  load 
current,  that  is  characteristic  of  all  stray  losses  is  val- 
uable data  when  considering  the  advisability  of  in- 
creasing the  continuous  rating  to  a  "maximum"  rating 
on  converters  without  making  changes  in  the  converter 
design  to  keep  the  current  densities  at  low  established 
values  in  those  parts  subject  to  stray  losses,  particu- 
larly the  brush  densities.  The  comparative  data  show- 
mg  the  efficiency  and  stray  losses  when  working  with 
appreciable  wattless  currents  illustrate  tnat  such  op- 
eration is  obtained  at  a  material  reduction  in  efficiency 
and  increase  in  stray  losses.  The  converter  is  essen- 
tially a  unity  power-factor  machine  and,  if  its  efficiency 
possibilities  are  to  be  fully  realized  and  rts  operating 
maintenance  kept  within  low  limits,  it  should  be  so 
operated.  The  comparison  of  efficiency  between  the 
booster  and  reactance  control  types  merely  confirms 
previous    experience    with    the    losses    in    converters 


In  summarizing  the  foregoing  data  it  is  interesting 
to  note  that  the  full  load  efficiency  of  the  booster  tvpe 
converter,  even  on  60  cycles,  does  not  vary  more  than 
0.40  percent  between  its  mid-voltage  and  its  extremes 
of  buck  and  boost  and  at  half  load  the  variation  in  effi- 
ciency  is   only  0.55    percent.     On   25    cvcle   units    the 


FIG.  3— EFFICIENCY  TESTS  BUCKING  TO  23O  VOLTS 

worked  at  low  power- factor.  The  machine  efficiencies 
at  most  do  not  differ  by  more  than  a  few  tenths  of 
one  percent  at  full  load,  while  if  the  total  losses  are 
summed  up  in  the  transformers,  transmission  lines  and 
power  house  generating  apparatus  due  to  the  low  pOv/- 
er-factor  operation,  the  comparison  will  be  on  an 
equitable  basis  and  permit  a  decision  based  on  all  of  the 
facts. 


294 


THE    ELECTRIC   JOURNAL 


Vol.  XYIII,  Xo. 


DISCUSSION    OF   STRAY    LOSSES 

In  forming  a  conception  of  the  possible  magni- 
tude of  stray  losses  and  the  differences  in  efficiency  of 
slightly  different  types  of  machines  based  on  test  re- 
sults, it  is  helpful  to  keep  in  mind  the  logical  magnitude 
that  such  losses  or  differences  might  assume  without 
indicating  unreliable  or  unavoidable  errors  in  testing. 
In  the  converter  armature  itself,  it  is  seiaom  appre- 
ciated what  a  large  percentage  of  the  full  load  losses 
are  constant  in  magnitude  and  not  subject  to  stray 
losses.  Referring  to  the  losses  in  Table  III,  the  first 
six  losses  are  not  subject  to  load  loss,  while  the  latter 
five  are.  Out  of  5.05  percent  total  loss  on  this  60- 
cycle  converter  there  is  only  2.07  percent  subject  to 
stray  loss  so  that  the  measured  stray  loss  of  0.80  per- 
cent at  mid  voltage  represents  an  increase  of  38  per- 
cent in  the  total  losses  represented  by  the  sum  of  iron, 
copper  and  direct-current  brush  losses. 

Stray  losses  are  incident  to  the  losses  in  three 
separate  parts  of  a  converter: — (i)  the  armature  iron; 

TABLE  IV— PERCENTAGE  OF  THE  SEGREGATED 
LOSSES  AND  EFFIENCIES 


Reactance  Co.i- 

trol  Convener 

12X  (30  V.)  Boost 

5<C  (15  V.)  Boost 
1640  kw. 

1740  kw 

Machine  Element 

Friction  and  Windage 

0.77 

0.64 

Brush    Friction 

0.54 

0.57 

Rotary  Shunt  Field 

0.28 

0.25 

Booster  Shunt  Field 

0.08 

0.00 

A.  C.  Brush  C-R 

0.22 

0.24 

Series  Comm.  Winding  C"R 

0.20 

0.22 

Rotary  Core  Loss 

0.93 

087 

Booster  Core  Loss 

0.16 

0.00 

Rotary  Arm.  C"R 

0.50 

0.61 

Booster  Arm.  C"R 

0.26 

0.00 

D.  C.  Brush  C=R 

0.44 

0.47 

Stray  Loss 

0.95 

1 

1.20 

Total  Loss 

540 

507 

Efficiency 

94.60 

9+93 

(2)  the  armature  copper;  and  (3)  the  direct-cur- 
rent brush  C-R.  Stray  losses  in  the  armature  iron 
are  caused  by  increased  magnetic  densities  due  to  the 
action  of  the  load  current.  The  booster  converter  at 
mid-voltage  has  an  armature  reaction  or  field  flux 
distortion  of  only  10  percent  as  great  a  magnitude  as 
an  alternating-currrent  generator  at  unity  power- fac- 
tor, due  to  the  fact  that  the  individual  alternating-cur- 
rent and  direct-current  reactions  almost  complete- 
ly oppose  each  other.  At  15  percent  boost  the  converter 
armature  distortion  is  increased  to  25  percent  and  ;..t 
15  percent  buck  is  reduced  to  five  percent  of  the  cor- 
responding alternating  current  generator  values. 
From  this  knowledge  of  the  internal  flux  relationships, 
it  is  evident  that  the  stray  iron  losses  of  a  converter 
are  materially  less  than  those  of  a  corresponding  size 
alternating  current  generator. 

,  The  increase  of  armature  copper  loss  due  to  buck- 
ing or  boosting  is  readily  obtained  from  a  considera- 
tion of  the  theoretical  relationships  of  the  converter 
annature  currents  and,  being  subject  to  calculation,  i> 
included   among   the   measurable   losses.     The   magni- 


tude of  the  eddy  current  losses  in  the  armature  con- 
ductors may  be  calculated  with  fair  accuracy,  as  is 
done  on  alternating  current  generators,  or  inay  be 
estimated  on  a  comparative  basis  by  comparing  the 
armature    conductor    and  slot    proportions  with    those 


■&4ss^- 

. 

l-i- 

.¥"^ 

i 

r 

^  01 

f 

0- 

^oXpSpL 

i 

/\ 

X 

/ 

/ 

0 

1 

Percent  U  ad  Current 

lj)0 

lis 

FIG.    4 — EFFICIENCY    TESTS    liOOSTING   TO    2g0   VOLTS 

used  ill  alternating  current  generator  practice.  Due  to 
the  opposition  of  the  alternating  and  direct  currents  in 
the  armature  winding  the  copper  loss  of  a  six-phase 
converter  at  mid-voltage  is  less  than  30  percent  of  that 
of  the  same  machine  as  an  alternating  current  genera- 
tor, and  correspondingly  there  is  only  about  33  per- 
cent of  the  copper  volume  available  to  be  subject  to 
eddy  losses.  The  converter  armature  slot  proportions 
are  again  much  more  favorable  from  the  eddy  current 
standpoint  than  those  of  the  alternating  current  ma- 
chine. 

The  direct-current  brush  C-R  loss  is  primarily 
a  matter  of  design  proportions  and  commutating  reac- 
tance voltage  and  secondarily  a  matter  of  coinmutating 
pole  adjustment.  The  stray  loss  in  this  connection  is 
caused  by  the  local  or  short-circuit  currents  set  up 
in  the  brush  face  and  the  commutated  armature  coils 
during  commutation,  and  may  amount  to  an  unexpect- 
edly large  magnitude.  Experience  has  shown  the  use 
of  direct-current  brush  densities  materially  in  excess 
of  50  amperes  per  square  inch  on  60  cycle  units  and 


FIG.  5 — EFFICIENXY  TEST  AT  MID  VOLTAGE  WITH  30  PERCLNT 
WATTLESS  LEADING  CURRENT 

(X)  amperes  per  square  inch  on  25  cycle  units,  resulting 
in  large  normal  brush  losses  and  brush  stray  losses  and 
has  a  most  important  influence  on  commutator  and 
brush  maintenance  expense.  The  best  assurance  of 
low  brush  stray  loss  is  obtained  by  designing  a  convert- 


July,  1921 


THE    ELECTRIC   JOURNAL 


er  of  low  commutating  reactance  and  small  brush 
short-circuit  currents,  which  condition  is  obtained  in 
modern  converter  design  by  using  the  minimum  num- 
ber of  commutator  bars  per  pole  that  is  safe  from  the 
flashmg  standpoint.  Modern  250  volt  converters  us- 
ing 18  bars  per  pole  on  60  cycle  and  21  bars  per  pole 
on  25  cycles  possess  commutating  and  performance 
characteristic  well  worthy  of  the  high  standard  of  Fdi- 
son  service,  and  while  somewhat  more  expensive  than 
the  older  units  using  higher  numbers  of  commutator 
bars  per  pole,  they  have  a  minimum  of  stray  losses  and 
give  a  materially  reduced  brush  maintenance  expense. 

COMMENTS  ON   INPUT-OUTPUT  TESTS 

The  determination  of  the  actual  operating  effi- 
ciency by  means  of  input-output  tests  is  bv  no  means 
the  simple  matter  it  may  appear  to  the  'uninitiated 
The  merits  and  demerits  of  this  type  of  testing  were 
thoroughly  reviewed  in  A.  I.  E.  E.  papers  in  191,  the 
most  optimistic  claim  for  its  accuracy,  under  ideal 
laboratory  conditions  was  a  plus  or  minus  range  of  o  ^ 


295 

Meter    Errors~Th^    direct-current     meters    mav 
readily  be  checked  before  and  after  tests  and  there  is 
more  likelihood  of  error  due  to  the  selection  of  type  of 
meter  (undampt  type  is  preferable)  and  careless'  lexel- 
mg  and  handling,  than  in  variation  of  calibration  con- 
stants.   The  ammeter  shunts  used  in  factory  laboratorv 
tests  may  be  calibrated,  but  once  installed  in  a  power 
company's    bus-bars,    these    shunts     represent    an    un- 
known   magnitude  of    error.     An    expedient    used    in 
these  particular  tests  for  the  purpose  of  further  elimm- 
ating  errors  was  the  use  of  entirely  independent,  dupli- 
cae    sets    of   meters  and    shunts.     The  external    mag- 
netic   fields    set  up  by   large   current  machines   or   the 
proximity  of  heavy  power  circuits  must  be  complete- 
ly neutralized  before  accurate  metering  is  possible      It 
js   always   essential    to  select  a   location  for  the    meter 
tables    where    the    stray    magnetic    fields  are    weakest 
Shielding  of  meters  by  enclosing  them  in  steel  ca-e^ 
whose  only  opening  is  a  slot  for  reading  th.  meter  scale 
■s  essential  in  all  cases,  as  experience  shows  that  even 


FIGS.   0    \M)   7-0  000    \MPERE.  ZQO— 260— 230  \ 

percent  while  the  general  concensus  of  opinion  fa- 
vored a  range  of  considerably  more  than  this  value 
The  general  theory  of  the  test  is  simple  enough  it  be- 
ing necessary  merely  to  obtain  simultaneous  readings 
of  three  single-phase  wattmeters  and  the  direct  rm- 
.«n  and  voltage.  The  percentage  accuracy  obtaina- 
ble  IS  dependent  primarily  upon  the  magnitude  of   the 

with  the  total  quantity  of  power  which  must  be  meas- 
J'ured  in  order  to  determine  it.  The  converter,  with  i^. 
ow  percentage  loss,  is  the  most  difficult  type  of  unit 
Z^  *f  ;r  "  "^-^^^^^  ■^-Vut-on.m  tests,  as  two 
be  measured   in  order  to    determine  a  quantity   of    the 

meters-    (^^T'7^^    Accuracy    and    constancy   of 
neters,    (2)    Reading  errors    of  observers ;    (,)    The 
oad  variation  or  swinging,  tha't  is  inevitable  on  al   com 
n  ercial    circuits    and    which    is    almost    impossible    to 

t™  f  r  °"  '^^°--'>-  ^-ts;  and   (4)%he    o 
stancy  of  the  machine's  no-load  losses. 


'LT,  60  CYCLE    S\NCHRON0L-S   HOUSTER   CONVERTER 

complete  shielding  is  not  absolute  protection  against 
stray  magnetic  fields.  The  steel  shielding  cages,  while 
c-'ttording  considerable  protection  from  external  fields 
also  put  the  meter  off  normal  adjustment,  due  to  the 
^teel  sides  acting  as  magnetic  shunts  to  the  permanent 
magnets  of  the  meters.  The  meter  should  be  kept  at 
least  two  inches  from  walls  of  the  shielding  cage  bv  be- 
ing firmly  wedged  in  place  by  wooden  blocks,  as  "even 
under  these  conditions  the  meter  reading  is  effected 
more  than  0.5  percent  by  the  shunting  effect  of  the  steel 
cage.  It  ,s  unnecessary  to  point  out  the  necessity  of 
cahbratmg  the  meters  under  the  conditions  of  the  actual 

Observation  Errors^Accuracy  in  simultaneous 
leadings  is  impossible  without  preliminary  training  of  a 
carefully  selected  crew  under  actual  testin. 
conditions.  Care  in  selection  of  testors  is  equal^ 
y  important  as  in  calibrating  meters  because 
e  test  results  are  no  more  dependable  than 
he  most  inefficient  meter  reader.  Even  the  most  care- 
fully selected  meter  readers  have  a  personal  correction 


296 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  7 


factor  which  cannot  be  eHminated,  but  which  can  be 
averaged  by  rotation  of  meter  readers  to  a  different  set 
of  meters  at  each  group  of  readings.  The  rotation  of 
meter  readers  is  usually  avoided  because  it  necessitates 
a  rather  long  period  of  training  to  familiarize  the  men 
with  all  of  the  meters.  Speed  and  accuracy,  however, 
are  not  synonymous  on  input-output  tests  where  con- 
sistency is  required.  Even  with  shielded  meters  it  is 
desirable  to  take  four  groups  of  readings  with  all  me- 
ters rotated  90  degrees  for  each  group  so  that  all  com- 
binations of  stray  fields  and  meter  illumination  are  aver- 
aged for  the  four  compass  positions. 

Fluctuating  Load  Errors — No  commercial  load  is 
absolutely  steady  and  the  nearest  approach  to  this  ideal 
is  obtained  in  laboratory  tests  by  loading  the  machine 
wholly  or  partly  on  a  resistance  load.  Most  commercial 
single-phase  wattmeters  are  considerably  less  damped 
than  the  direct-current  ammeters  and  voltmeters,  re- 
sulting in  the  alternating-current  and  direct-current 
meters  swinging  unsynchronously  with  changes  in  load 
or  in  supply  voltage.  This  load  swinging,  when  infre- 
quent, may  be  minimized  in  effect  by  an  additional  un- 
damped alternating-current  meter  to  indicate  those 
readings  taken  during  a  change  in  load.  It  is  cus- 
tomary to  take  ten  consecutive  simultaneous  reading 
of  all  meters  at  ten  second  intervals;  however,  in  ihese 
tests  15  readings  were  taken  and  the  five  readings  cor- 
respondintj   to  anv   load   change   as   shown  on  the   un- 


damped meter  were  discarded,  leaving  ten  readings  un- 
der steady  load  conditions. 

Single-Phase  Polyphase  Wattmeters — The  use  of 
three  single-phase  wattmeters  is  preferred  over  a  poly- 
phase indicating  meter,  partly  because  the  single-phase 
meters  are  not  readily  subject  to  improper  connections, 
and  chiefly  because  experience  with  the  two  types  on 
the  same  tests  leaves  one  more  favorably  impressed 
with  the  consistency  and  accuracy  of  the  single-phase 
method.  On  the  basis  of  probability  of  error,  the  use 
of  three  meters  is  preferable  to  one  meter,  as  any  slight 
error  on  single  phase  is  averaged  between  three  meters 
and  has  a  fair  chance  of  being  neutralized  by  the  read- 
ings of  the  two  other  observers. 

The  polyphase  wattmeter,  consisting  of  two  cur- 
rent and  voltage  elements  transmitting  their  torque  to 
a  common  shaft,  is  readily  subject  to  errors  in  connec- 
tion on  the  six-phase  diametrical  circuits  used  on  con- 
verters. With  absolutely  balanced  low  tension  con- 
verter currents  there  are  two  voltage  connections 
which  give  correct  Vesults,  but  with  the  untialance  of 
low-tension  current  that  is  common  to  heavy  current 
converters  due  to  unavoidable  inequalitties  of  low  ten- 
sion lead  reactance,  there  is  only  one  correct  connec- 
tion, the  other  possible  connection  giving  errors  of  the 
magnitude  of  two  percent  plus  or  minus  on  converters 
with  slightlv  unbalanced  low-tension  current. 


Tho 


.AKiOiuaiic  Ekcia'ic  Bake  Ovoii 


JOHN  M.  STRAIT  and  J.  C.  WOODSON 

Industrial  Heating  Section, 
Westinghouse  Electric  &  Mfg.  Company 


DURING  the  last  decade  industrj'  after  industry 
and  process  after  process  has  been  electrified  and 
yet  the  baking  industr)',  one  of  the  oldest  in  the 
world,  is  among  the  last  to  take  advantage  of  the  in- 
herent qualities  of  electric  heat.  Bread  baking  has 
gradually  grown  into  one  of  the  largest  industries  in 
existence.  Evolution  and  the  centralizing  of  population 
in  the  cities  gradually  demanded  larger  equipment  and 
better  methods  of  baking  bread  scientifically  and  in 
large  quantities.  To  meet  these  conditions  a  constant, 
uniform  temperature  in  the  baking  chamber  is  of  fun- 
damental importance. 

In  early  methods  of  baking  practically  no  attention 
was  given  to  the  uniformity  of  heat  during  the  bake. 
The  principal  object  was  to  have  the  oven  at  approxi- 
mately the  baking  temperature  at  the  beginning  of  the 
bake  but  no  means  were  provided  to  hold  this  tempera- 
ture for  any  length  of  time.  Only  within  the  past  fif- 
teen years  has  any  real  persistent  engineering  eft'ort 
been  made  to  establish  the  baking  industry  with  ovens 
of  modern  types  and  designs,  and  even  today  we  find 
in  many  of  the  large  as  well  as  the  small  bakeries,  the 
eld  brick  "kiln  type"  oven.     These  ovens  are  nearly  all 


gas  or  coal  fired  and  represent  practically  no  advance 
in  this  art  for  generations  past. 

Perhaps  the  most  important  step  forward  was 
taken  when  gas  ovens  of  the  "ferris  wheel  type"  were 
brought  out.  These  ovens,  while  not  entirely  satisfac- 
tory for  a  number  of  reasons,  represented  a  great  ad- 
vance, for  the  rotation  of  the  bread  in  the  baking  cham- 
ber insured  having  each  tray  pass  successively  through 
the  same  temperature  zones,  which  means  that  every 
loaf  will  bake  uniformly  and  brown  evenly  all  over. 
Even  baking  and  browning  of  the  bread  requires  that 
the  oven  be  heated  uniformly  from  end  to  end  of  the 
baking  chamber,  for  if  one  is  hotter  than  the  other,  the 
bread  will  bake  faster  at  that  end,  necessitating  either 
unloading  the  oven  one  end  at  a  time  or  over  browning 
the  loaves  on  the  hot  end.  However,  all  the  loaves  on 
each  end  will  be  at  the  same  degree  of  brownness.  Un- 
even temperature  in  the  two  ends  of  the  oven  has  been 
a  source  of  great  trouble  in  gas-fired  ovens,  requiring 
constant  attention  and  manipulation  of  the  gas 
burners.  Also  gas  ovens  are  rarely  provided  with  any 
sort  of  heat  insulation,  thus  being  quite  uneconomical 
ar  well  as  disagreeable  to  work  with,  and  even  danger- 


July,  1 92 1 


THE   ELECTRIC   JOURNAL 


ous  as  a  fire  hazard.  Also  gas  ovens  do  not  have  auto- 
matic temperature  control,  resulting  in  poorer  quality  of 
bread  and  increased  labor  costs,  due  to  the  greater  at- 
tention required  for  each  oven. 

Recognizing  the  superiority  of  the  general  principle 


297 

plications  of  enameling  and  baking  ovens  for  a  number 
of  years. 

The  matter  of  economy,  however,  introduced  the 
principal  objection  to  this  combination  and  the  next  im- 
portant step  was  a  reduction  of  the  radiation  losses  to 
ihe  lowest  possible  figure.  The  result  is  the  automatic 
electric  bake  oven  of  the  type  shown  in  Fig.  2,  in  which 


FIG.    I— REVOLVING  OVEN,  WITH  GAS   HEATERS  REPLACED  BY  ELECTRIC 
HEATERS 

Installed  at  McCann's  Bakery,  Pittsburgh, 
of  the  revolving  type  of  oven,  exhaustive  experiments 
were  conducted  by  substituting  electricity  for  gas  in  an 
oven  of  this  general  construction,  with  results  that  were 
highly  satisfactory  in  every  detail.  The  oven  shown  in 
Fig.   I    is  a  gas  oven  equipped  with   standard  electric 


FIG.    2— AUTOMATIC    ELECTKl.-    I;  \K|     i.\lx' 

Installed  in  the  West  Penn  Hospital,    Pittsburgh.    Showing 
the  thermometer  and  thermostat. 

heaters  and  automatic  temperature  control,  which  has 
been  operating  successfully  for  over  a  vear.  The  elec- 
trical equipment  used  has  been  operating  successfully 
n^  many  industrial  plants  throughout  the  countrv  in  ap- 


FIG.   3— ELECTRIC   OVEN    IN   THE  DICKSON   BAKERY,    MANSFIEl.H,  OHIO 

The  open  door  forms  a  convenient  shelf, 
the  temperature  is  automatically  maintained  at  any 
desired  point  without  attention.  Due  to  the  inherently 
superior  heating  medium,  a  totally  enclosed  baking 
chamber  replaces  the  non-insulated  open  oven  which 
was  required  for  the  proper  combustion  of  the  gas  used 
in  many  bake  ovens. 

These  ovens  are  rated  at  25  kw  on  any  standard 
voltage.     The  objects  to  be  obtained 
were  uniformity  of  heat  distribution; 
automatic     control    of     temperature; 
low  radiation  losses ;  flexibility  of  de- 
sign  (easily  adapted  to  a  number  of 
different       requirements)  ;       reduced 
first  cost  of  oven  and  operation ;  oven 
to  be  shipped  assembled  or  nearly  so ; 
and   oven   to   present   a   neat,    clean, 
finished  appearance.  The  first  model 
constructed    along    these    lines     has 
been  placed  in  a  local  bakery.  Fig.  3 
where  it  has  been  in  daily  operation 
for    several    months,    turning    out    a 
very  uniform  prdduct  day  after  day. 
The    oven    is    finished    in     white 
vitreous     enamel    with    nickel    trim- 
mings.    The  walls    are    packed    with 
three  inches  of  high  grade  heat  insu- 
j    lating  material  and  the  oven  contains 
eight  trays  attached  tp  a  reel  which 
makes    one    complete    revolution    per 
minute.  The  door,  when  open,  forms 
a    shelf    convenient    for    the    loading 
of  the  baked  products.     The  capacity  of 
the  oven  depends  upon  the  products  baked  and  the  size 
of  pans  used.     It  will  bake  96  standard  24  oz.  Toaves 
and  120  one  pound' loaves  at  one  time  or  approximately 


the    location    of 


and  unloadiiu 


298 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No. 


130  large  loaves  and  200  small  loaves  per  hour. 

The  automatic  control  feature  centered  in  the  elec- 
tric thermostat  insures  the  proper  baking  tempei^ature 
v.'ithout  any  attention  whatsoever.  After  the  oven  is 
connected    to    the    circuit   by    the    mere    pushing   of   a 


ovi-N  ii:ami\m 


lutton,  the  baker  i.s  assured  that  the  proper  baking  heat 
i>  being  maintained  with  absolute  certainty,  bake  after 
bake  and  day  after  day  without  the  least  attention  on 
his  part.  It  is  maintained  automatically,  and  even 
though  the  oven  is  idle  for  a  short  period  the  thermo- 
stat turns  the  heat  on  and  off  and  keeps  the  baking  tem- 
1  erature  inside  the  oven  within  very  close  limits.  In 
fact  the  oven,  with  its  control  accessories,  is  almost 
human  in  its  operation  and  allows  the  baker  to  prepare 
his  bread  under  the  most  ideal  conditions  and  secure 
maximum  output  with  almost  clock-like  regularity. 

I'.ven  though  the  heaters  are  rated  at  25  kw  maxi- 
mum, the  automatic  control  equipment  tnrn<  the  he'it- 


FIG.  5 — HEATER  INSTALLATION 

ers  on  and  off  in  its  functioning  to  maintain  the  pro])er 
baking  temperature  and  as  a  result  the  actual  power 
consumption  is  considerably  less  than  the  maximum  and 
averages  from  18  to  20  kw-hrs.  depending  upon  the 
]>roducts  baked.     The  insulated  baking  chamber,  with 


its  almost  negligible  radiation,  losses,  can  be  brought  to 
a  baking  temperature  of  450  degrees  F.  in  45  minutes. 

With  an  electric  oven  which  is  controlled  auto- 
matically, the  bake  shop  assumes  the  aspect  of  a  well- 
regulated  factor}-,  as  the  old  rule  of  thumb  methods  are 
replaced  by  systematic  routine.  Since  all  operations  of 
these  ovens  can  be  reduced  to  a  positive  time  basis,  the 
whole  scheme  of  baking  becomes  a  cyclic  operation 
with  the  positive  assurance  that  eveiy  35  minutes  one 
bake  can  be  removed  and  the  next  placed  in  the  oven 
with  no  intermediate  attention  whatsoever.  This  fea- 
ture allows  the  baker  to  time  all  other  operations  of  his 
shop  so  that  a  steady  stream  of  dough  from  the  form- 
ing rolls  through  the  "proofing"  chamber  will  be  ready 
to  refill  the  oven  at  the  end  of  each  baking  cycle.  This 
saves  time,  labor,  confusion  and  makes  for  economy 
and  maximum  production  in  the  smallest  space. 

As  gas  ovens  and  non-automatic  electric  ovens  re- 
cjuire  so  much  attention  to  gas  valves  and  control 
switches,  this  systematizing  of  the  bakerv  is  almost  out 


FIG.   6— THE   CONTROL  THER.MOST.\T 

of  the  question  with  them.  Either  the  oven  has  to  be 
brought  to  the  right  temperature  while  the  bread  waits 
and  over-proofs,  or  the  bread  is  put  into  the  oven  when 
it  is  properly  proofed,  regardless  of  the  oven  tempera- 
lure.  No  labor  or  time  is  saved  with  these  ovens  and 
you  can  not  judge  by  one  bake  what  the  quality  of  ilie 
next  will  be. 

Details  of  construction  of  the  new  oven  are  shown 
in  Figs.  4  and  5.  As  will  be  seen  this  oven  is  built  as  a 
luiilding  is  constructed ;— cast  iron  angle-section  end 
frames  tied  together  with  structural  steel  angles  and 
channels  foi-m  the  interior  frame  work  upon  which  the 
unit  panels  of  the  oven  walls  are  supported.  These 
I^anels  are  made  of  galvanized  sheet  steel  on  the  out- 
side, a  rust  resisting  black  sheet  steel  on  the  inside  and 
filled  between  with  three  inches  of  "felted"  mineral 
wool  which  is  one  of  the  best  heat  insulators  known,  be- 
sides possessing  other  necessary  qualities  such  as  being 
"non-settling",  light,  non-hydrating  and  having  a  dis- 
tinct springiness,  so  that  it  can  be  packed  into  a  space 


July,   1 92 1 


THE    ELECTRIC   JOURNAL 


299 


and  will  exert  a  force  outward,  insuring  that  the  space 
will  remain  filled.  The  number  of  bolts  going  into  the 
oven  is  small,  thus  reducing  the  "through  metal"  losses 
to  a  minimum.    The  supporting  hooks  for  the  unit  tray 


FIG.   7 — THE  CONTROL  PANEL 

or  shelf  are  composed  of  bronze  with  grooves  inlaid 
with  graphite,  thus  needing  no  further  lubrication.  The 
hooks  afford  a  ready  means  of  removing  trays  from 
oven  through  the  door  or  replacing  them.  The  tray 
bottom  is  perforated   to  allow   free   circulation  of  the 


^^\  t^^ 

^V""- 


vw^ 


^1 


S5SI- 


Connections  for  220  Volt  -  3  Phase  Panel 
FIG.  8 — SCHEMATIC  DIAGRAM   OF  AUTOMATIC  TEMPERATURE  CONTROL 

heated  air  round  the  work,  and  a  back  stop  is  provided 
in  order  that  work  will  not  be  pushed  over  the  back 
edge  of  the  tray. 

A  detailed  view  of  the  control  thermostat  is  shown 
in  Fig.  6  and  the  control  panel  in  Figs.  7  and  8.     The 


thermostat  is  mounted  on  the  end  of  the  oven  with  the 
bulb  inserted  in  the  middle  of  the  oven  top  but  the  con- 
trol panel  can  be  located  where  most  convenient,  in  the 
basement,  adjacent  room,  or  as  is  frequently  done, 
mounted  high  up  on  the  wall. 

An  adjustable  baffle  plate  is  mounted  directly  above 
the  heaters ;  as  is  well  known,  the  highest  end  of  the 


even  will  be  the  hottest  unless  compensated  for.  By 
raising  or  lowering  this  baffle  plate,  both  ends  of  the 
oven  can  be  made  to  bake  alike,  even  though  the  oven 
itself  is  not  level.  The  revolving  "ferris  wheel"  is 
rotated  by  a  1/6  hp  motor  through  suitable  reduction 
gears  Fig.  9,  to  give  slightly  less  than  one  r.p.m.  on  the 
reel.  The  motor  pinion  is  bakelite-micarta  which  gives 
noiseless  operation  of  the  gears.  The  reel  shaft  rides 
ii;  bronze-graphite  bearings,  so  it  does  not  have  to  be 


/ 

/ 

^ 

s 

r 

/^ 

/ 

-1- 

■0 

f^ 

^ 

i 

r 

30-&- 

3 

1 

A 

e 

-i^; 

/ 

Room 

b=rrS 

F  "" 

4- 

j^ 

>y 

^ 

1 

315  ■ 

«mper  ture  - 

0 

F 

■5^0— 
1 

FIG.   10 — CONSTANT  RADIATION  LOSS  AT  DIFFERENT  BAKING 
TEMPER.ATURES 

lubricated  otherwise.  Lubricating  oil  would  not  stand 
the  temperatures  these  bearings  reach,  approximately 
500  degrees  F.  A  vent  pipe  is  provided,  because  baking 
bread  gives  off  considerable  carbon  dioxide  and  other 
disagreeable  gases  which  affect  the  eyes  and  nostrils, 
and  so  should  be  carried  outside  the  room. 

Curves  in  Figs.  10  and  11  show  the  characteristics 
of  this  oven.     The  time  of  heating  the  oven  up  to  bak- 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  7 


ing  temperature  is  45  minutes,  as  compared  with  2.5 
hours  on  the  converted  gas  oven  referred  to  in  the  first 
part  of  this  article,  and  the  radiation  loss  at  450  degrees 
F.  is  approximately  one-third  of  the  loss  shown  at  the 
same  temperature  in  the  converted  gas  oven.     Fig.  12 

TABLE  I — POWER  REQUIRED  FOR  BREAD  BAKING* 


Total  Kw-Hr  Required 

Watts  Required  per    I 

for 

Run 

Loa 

d 

Mo.  of 

Bakes 

Loaves 

Continuous 

Intermittent 

Continuous 

mittent 

Baking 

Baking 

Baking 

Baking 

1 

96    , 

33.2 

52 

346 

540 

2 

192     ,■ 

47.2 

64.7 

246 

350 

3 

288  ■ 

61.2 

100.5 

212 

337 

4 

384 

76.2 

128 

196 

334 

5 

480 

89.2 

137 

185 

286 

6 

576 

103.2 

179 

7 

672 

117.2 

175 

8 

768 

1S1.2 

171 

9 

864 

145.2 

188 

10 

960 

157.2 

166 

shows  a  recording  thermometer  chart  taken  on  the 
Westinghouse  autotnatic  oven. 

From  Table  I  it  will  be  seen  that  the  watthours  and 
hence  the  cost  per  loaf,  decreases  as  the  number  of 
bakes  per  day  is  increased.  These  figures  are  based 
upon  continuous  baking  and  will  be  increased  as  the 
idle  time  between  bakes  is  increased,  so  that  it  is  greatly 
to  the  advantage  of  the  baker  to  operate  these  ovens 
continuously. 

The  automatic  temperature  control  produces  many 
distinct  advantages,  chief  among  which  are: — The  bak- 


Off 

<00 

/ 

N 

s. 

y 

f 

s 

\, 

1.00 

/ 

V 

"^ 

1 

'          ■ 

"— - 

■— 

- 

E 

•1-200 
1 

/ 

/ 

— 100 

/ 

' 

i 

B 

i 

J 

TimKinMin 

1 

ites 

0 

'^ 

i  0     : 

FIG.   II — TEMPERATURE  WITH  CONSTANT  INPUT 

Room  temperature,  68  degrees  F. 
ing  temperature  is  uniform,  regardless  of  whether  the 
oven  is  completely  loaded  or  not,  insuring  a  uniform 
product  and  the  ability  to  duplicate  results  day  after 
day.  No  attention  need  be  paid  the  oven  other  than  to 
put  in  the  bread  and  take  it  out  at  the  proper  time.     By 

•Oven  loaded  with  96  one  and  one-half  pound  loaves  per  bake;  tem- 
perature 500  degrees  F;  time  of  bake  33  minutes.  If  proper  pans  are 
used  this  oven  will  hold  112  one  and  one-half  pound  loaves  per  bake. 


permitting  the  operator  to  give  his  entire  attention  to 
other  details  during  the  baking  period,  considerable 
labor  saving  is  eft'ected. 

The  complete  thermal  insulation  not  only  affords  a 
considerable  saving  in  electricity  but  permits  a  cooler 
workroom.  This  feature  permits  the  installation  of  the 
oven  directly  in  tl^e  sales  or  display  room  of  the  bakery 
without  inconvience  to  customers.  The  advertising 
feature  of  baking  bread  and  cakes  scientifically  and 
under  complete  sanitary  conditions  by  electricity, 
places  the  baker  immediately  in  an  up-to-date  and  pro- 
gressive class.  Due  to  the  elimination  of  combustible 
gases  the  fire  hazard  is  entirely  eliminated. 

There  is  a  wide  field  of  application  of  the  auto- 
matic bake  oven  aside  from  its  use  in  bakeries.  Hotels, 


riG.   12— TEMPERATURE  MAINTAINED  DURING  SUCCESSIVE  BAKES 

restaurants,  hospitals  and  public  institutions,  private 
clubs  and  large  industrial  plants  all  have  a  demand  for 
fresh  bread,  rolls,  specially  baked  cakes  or  fancy 
pastries,  which  can  be  turned  out,  with  such  equipment, 
just  when  needed,  at  minimum  cost,  and  of  the  highest 
quality.  For  such  applications,  neat  and  attractive  ap- 
pearance is  an  asset  surpassed  only  by  the  clean  and 
sanitary  arrangement,  the  uniformity  of  product  and 
the  economy  of  operation. 

From  the  standpoint  of  central  stations,  these  ovens 
will  add  a  desirable  load.  The  phases  are  balanced,  the 
load  is  at  lOO  i)ercent  power-factor,  and  in  most  bake 
shops  will  come  at  "off^  peak"  hours,  as  the  day's  bake 
usually  starts  soon  after  midnight,  when  all  central  sta- 
tion loads  are  lowest,  especially  in  the  smaller  towns 
cities. 


Eloctrlcaly  Opsraiod  Ocmii  Car  Ujiioadcii^s 


R.  T.  KINTZING 

Control  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


THE  Northern  Central  grain  elevator  of  the  Penn- 
sylvania Railroad  Company  at  Baltimore,  Mary- 
land has  a  grain  storage  capacity  of  approxi- 
mately five  million  bushels,  only  half  that  of  the  largest 
Canadian  storage  elevators,  but  in  grain  handling 
capacity  it  is  twice  as  large  as  any  other  elevator.  Lo- 
cated on  the  harbor  front,  its  piers  can  accommodate 
five  ocean  going  vessels  at  one  time.  It  is  equipped 
with  the  latest  and  most  modern  type  of  machinery  de- 
signed for  the  most  efficient  handling  of  bulk  grain. 

Foremost  among  the  many  labor  and  time  saving 
devices  are  the  grain  car  dumpers  in  the  unloading 
room.  Four  of  these  machines,  side  by  side,  with  an 
operating  crew  of  eighteen  men,  can  unload  four  hun- 
dred cars  daily,  each  car  containing  from  1200  to  2000 
bushels    of     grain.      The    average    is     twenty-five    to 


quired  to  sustain  the  weight  of  locomotives  passing 
over  them.  They  consist  of  a  bridge  approximately 
60  feet  long,  supported  on  a  large  central  shaft  in  tru- 
nion  bearings  and  arranged  to  be  tilted  45°  in  either 
direction  endwise  and  30°  sidewise  in  one  direction. 
Automatic  means  for  clamping  the  cars  in  place  on 
the  bridge  are  provided  at  the  ends  and  sides  of  the 
cars  and  automatic  means  of  opening  and  lifting  grain 
doors  are  included.  A  motor-operated  car  puller  is 
used  to  pull  up  a  string  of  loaded  cars  and  to  spot  the 
cars  in  the  center  of  the  bridge. 

The  cycle  of  operation  begins  with  the  bridge 
horizontal,  with  end  posts  under  each  end  to  prevent 
endwise  tilting,  with  end  damps  depressed  below  the 
level  of  the  track  to  permit  cars  to  be  run  onto  the 
bridge,    with    side  "clamps  and    door    opener?    barked 


thirty  cars  per  dumper  in  each  eight  hour  shift,  with 
only  three  men  actually  assisting  in  the  dumping  oper- 
ation. Prior  to  the  installation  of  these  machines,  four 
men  were  required  to  unload  eight  cars  in  eight  hours. 
The  average  time  for  unloading  one  car  is  ten  minutes. 
During  the  operation  of  unloading  314  cars,  it  was  ob- 
served that  one-third  of  them  were  unloaded  com- 
pletely in  eight  minutes  each. 

These  facts  become  more  impressive  when  it  is  re- 
membered that  grain  is  shipped  in  standard  size  box 
cars  with  side  opening  doors  and  separate  wooden 
grain  doors  usually  nailed  to  the  framework  of  the  car. 
After  the  doors  are  opened  the  car  is  emptied  by  tilting 
It  in  several  directions  to  permit  all  of  the  grain  to 
flow  out  of  the  car  door.  Small  cars  are  tilted  once 
each  way  only  and  large  cars  are  tilted  twice. 

The  car  dumpers  were  designed  and  built  bv  the 
Lmk  Belt  Company,  were  installed  under  the  direction 
of  Jas.  Stewart  &  Co.,  Inc.,  grain  elevator  contractors, 
and  were  made  unusually  heavy  because  thev  were  r^-- 


FIG.  2 — CAR  TILTED  30  DEGREES  TO  ONE  SIDE 


away  from  the  bridge  in  extreme  positions.  The  op- 
erator manipulates. the  car  puller  to  pull  a  car  to  the 
approximate  center  of  the  bridge.  The  end  clamps  are 
then  run  up  against  the  bumpers.  The  end  clamp  mo- 
tors drive  the  clamps  through  screws  and  travelling 
nuts  and  are  stopped  by  current  limit  relays  when  the 
clamps  have  exerted  sufficient  pressure  against  the 
couplings  to  stall  the  motors.  After  the  end  clamp 
motors  have  been  stopped  in  this  manner,  it  is  possible 
to  operate  the  side  clamp  motors,  one  at  either  end  of 
the  car,  to  push  out  the  side  clamps  which  are  intended 
to  support  the  car  as  it  tilts  over  sidewise.  Cur- 
rent limit  relays  are  also  used  to  stop  these  motors,  and 
after  the  motors  have  been  stopped  in  this  manner 
it  is  possible  to  run  the  door  opener  forward  to  push 
in  the  grain  door.  The  car  door  has  been  opened 
previously  to  prevent  damage  to  the  car. 

The  original  layout  included  a  motor  and  control 
for  lifting  the  grain  door  above  the  floor  of  the  car  to 
permit   escape  of   the  grain   before  the  car   was   tilted. 


302 


THE    ELECTRIC    JOURNAL 


\o\.  XVIII,  No.  7 


This  motor  was   not  used,   however,   and  the  door  is 
lifted  manually  by  means  of  levers. 

Lifting  the  grain  door  permits  grain  to  begin  to 
flow  out  of  the  car  and  in  order  to  accelerate  this  flow 
of  grain,  the  car  is  tilted  30  degrees  sidewise  at  whicli 
time  the  electrical  circuits  are  completed  which  enable 
the  operator  to  remove  the  end'  posts,  and  to  tip  the 


FIG.   3 — CAR    llI.TEn   KN'DWISE 

Showing  the  iiiclined  position  of  the  platform  on  whieh  the 
workmen  stand. 

car  45  degrees  endwise.  The  car  is  tipi)ed  to  the 
other  extreme  position  and  then  restored  to  a  horizon- 
tal position  and  undamped  by  the  reverse  of  the  cycle 
just  described. 

When  the  car  has  been  entirely  emptied,  the  end 
post  under  the  elevated  end  of  the  bridge  is  inserted 
and  the  bridge  is  started  down  toward  that  end.  In- 
•sertion    of    the   end    i)o.st    brings   into    operation    an 


FIG.   4 —CAR  TILTED   IN   OPPOSITE  DIRECTIOX 

Showing  the  bridge  mechanism  and  part  of  the  concrete 
counterweight. 

auxiliary  limit  switch  which  causes  the  bridge 
to  slow  down  an  stop  in  the  mid  or  horizontal 
position  at  which  time  the  other  end  post  is  put  under. 
The  car  is  then  restored  to  a  horizontal  position  and  un- 
damped by  first  removing  the  door  pusher  and  side 
clamps,  and  is  pushed  oiif  the  bridge  by  the  next  loaded 
car. 


All  the  operations  are  completely  interlocked  so 
as  to  make  it  absolutely  necessary  to  adhere  to  a  pre- 
determined cycle  of  operation  and  any  departure  from 
this  predetermined  cycle  immediatey  makes  the  control 
inoperative  and  makes  it  necessary  for  the  operator  to 
hold  down  some  push  buttons  while  correcting  faulty 
operation  and  restoring  the  action  of  the  control  to  its 
previous  condition. 

The  power  supply  is  three-phase,  2^  cycles,  550 
volts  alternating  current,  and  the  motors  used  are  of 
both  the  squirrel-cage  and  the  wound-rotor  induction 
type.  The  main  controllers  are  in  the  form  of 
switchboards  on  which  are  mounted  the  necessary 
magnetically-operated  contactors,  relays,  etc.  The 
operator's  switches  are  small  drum  type  controllers, 
one  for  each  operation  of  the  dumper.  All  of  this 
equipment  must  be  enclosed  in  order  to  avoid  dust  ex- 
plosions. All  of  the  limit  switches  mounted  on  the 
duinpers  are  enclosed  in  dust  proof  boxes.  The 
wound-rotor  motors,  with  exposed  current  carr>'ing 
parts,  are  covered  and  the  control  panels  are  mounted 


EH..    S       VIEW    EKO.M    OTHEK  SlIlE  of    HL.MPEK 

This  illustration  gives  a  good  idea  of  the  arrangement  of 
the  door  pusher  and  side  bolsters  on  the  adjacent  track. 

in  dust  jiroof  hou.ses  at  the  top  of  the  unloading  room 
where  they  are  farthest  removed  from  the  source  of 
dust.  The  operators'  compartments,  below  the  con- 
trol house,  are  encased  in  glass. 

A  general  view  of  the  unloading  room  is  given  in 
Fig  I.  The  dumi)er  in  the  foreground  is  in  position 
to  receive  a  loaded  car.  End  clamps  are  down  in  the 
|)its  beneath  the  track  level;  side  bolsters  and  door 
pusher  are  backed  out  to  their  limits  to  avoid  striking  the 
approaching  car.  At  the  right  near  the  center  is  the 
lop  of  the  hopper  into  which  the  grain  is  poured. 
The  operators'  compartments  are  built  out  from  the 
columns  at  the  side  of  and  above  the  dumpers  to  give 
the  best  possible  view  of  the  unloading  operation.  The 
controller  houses  are  directly  above  the  operating 
rooms.  This  view  shows  also  the  construction  of  the 
side  bolsters  and  door  pusher.  The  top  part  of  the 
bridge,  on  which  are  mounted  the  end  clamps  and  side 
bolsters,  is  a  cradle  which  is  rotated  on  the  rollers 
shown  in    the  left    foreground  to   tilt  the  car   sidewi.se. 


July,   1 92 1 


THE    ELECTRIC   JOURNAL 


The  door  pusher  does  not  tilt  with  the  cradle.  It 
is  pushed  out  securely  against  the  grain  doors  and  re- 
moves this  door  on  account  of  the  relative  motion  be- 
tween the  door  pusher  and  the  car  as  it  tilts  sidewise. 

A  car  is  shown  in  Fig.  2  clamped  in  the  cradle  and 
tilted  to  the  extreme  side  position.  The  operating 
crew  consists  of  three  men.  The  end  clamps  rise  out 
of  the  pits  as  they  are  pulled  forward  ana  when  they 
strike  the  car  couplings  the\-  continue  until  the  pressure 


FIG,    (t ISdTTOM    OF  CAK  DU.Ml'FR 

The  grain  hopper  and  cover  over  the  end  tilted  motor    a^ 
well  as  ihe  counterweights  and  gear  drive  are  plainly  shown.' 

exerted  stalls  the  end  clamp  motor.  A  current  limit 
relay  on  the  control  panel  disconnects  the  motor  after 
it  has  been  stalled.  Prior  to  this,  due  to  interlocking 
of  the  control  circuits,  no  other  part  of  the  dumper  can 
be  operated  and  after  its  occurrence  onlv  the  side  bol- 
sters can  be  moved.  There  are  two  of  these,  one  at 
each  end  of  the  car.  Both  must  be  moved  out  against 
the  car  and  both  operating  motors  must  be  stalled  be- 
fore any  more  of  the  control  is  energized. 

Both  the  end  clamps  and  the  side  bolsters  may  be 
run  back  and  forth  as  often  as  desired  before  thev  are 
stalled  but  after  either  one  has  been  stalled  and  the 
succeeding  operation  has  been  started,  then  an  it- 
tempt  to  operate  either  of  them  will  immediatelv  de- 
energize  all  the  control  and  el¥ectuallv  prevent  un- 
clampmg  the  car  when  it  may  be  in  an  unstable  posi- 
tion. The  same  idea  is  carried  out  in  the  complete  cy- 
cle of  operation  and  is  effective  in  both  directions  • 
1.  e.,  whether  the  car  is  being  clamped  and  unloaded  or 
being  returned  to  normal  position  and  undamped.  To 
restore  normal  conditions,  the  operator  must  hold 
down  push  buttons  at  some  little  trouble  until  he  has 
corrected  his  mistake. 

When  the  side  bolsters  have  been  stalled,  the  con- 
trol for  the  door  pusher  motor  and  the  side  tilting  mo- 
tor are  energized.  The  door  pusher  advances,  strikes 
the  gram  door,  pushes  the  boards  into  the  car  and 
stops  automaticalh-.  The  car  tilts  sidewise  'until 
stopped  by  the  opening  of  a  geared  limit  switch  con- 
trolled -  by    the    side    tilting    motor.     The     same    limit 


30.3 

switch  establishes  a  circuit  which  releases  magnet-op- 
erated latches  on  the  end  posts  and  thereby  makes  it 
mechanically  possible  for  the  operator  to  remove  these 
end  posts.  Levers  for  this  purpose  are  mounted  in  the 
operating  room. 

Switches  operated  by  the  removal  of  the  end  posts 
complete  the  circuit  for  the  end  tilting  control  and  per- 
mit the  bridge  and  car  to  be  tilted  endwise,  as 
shown  in  Figs.  3  and  4.  A  geared  limit  switch  auto- 
matically causes  the  tilting  motor  to  slow  down  and 
stop  at  the  extreme  positions.  A  two-speed  induction 
motor  IS  used  for  this  purpose.  The  slow-speed  con- 
nection is  useful  in  giving  a  positive  slow  down  be- 
fore the  bridge  comes  to  rest  and  the  brake  is  set. 
The  bridge  is  partially  counterweighted,  as  shown  in 
Figs.  4  and  6.  In  practice  it  is  always  tilted  hrst  in 
ihe  direction  which  lifts  the  counterweight.  Then  the 
weight  is  able  to  assist  in  moving  the  unbalanced  load 
"f  the  partly  empty  car  in  the  other  direction. 

When  the  car  has  been  emptied  and  it  is  desired 
to  stop  the  bridge  in  the  horizontal  position,  the  opera- 
tor replaces  the  end  post  under  the  elevated  end  of  the 
bridge.  This  action  cuts  in  an  auxiliarv  limit  switch 
which  automatically  slows  down  and  stops  the  motor 
when  the  bridge  is  approximately  horizontal.  Exact 
spotting  level  with  adjacent  tracks  is  done  from  an 
"inching"  push  button  which  is  effective  onlv  when  the 
bridge  is  nearly  in  place  on  the  end  posts.  "  When  the 
operator  replaces  the  .second  end  post,  the  side  tilt  con- 
trol, which  is  de-energized  as  long  as  eitner  end  post 
IS  removed,  is  again  energized  and  the  car  may  be 
brought  to  a  level  position.  When  it  readies  this  posi- 
tion, other  contacts  on  the  side  tilt  limn  switch  re- 
establish the  circuit  for  the  side  bolsters  and  door 
pusher.       These,  in  turn,  ^^  hen  they  have  reached  their 


FK,     7— CONTROI    r\%EI    WITH    THE    \L  MI  I  \RY  CONTROL    XPPAR^TUS 

extreme  position  away  fn.nn  the  car,  re-csrablish  tlie 
circuit  for  the  end  clamj)  control  and  the  car  can  be 
completely  released.  From  this  point,  it  is  pushed  off 
the  bridge  by  the  next  oncoming  car. 

It  will  be  seen  from  the  above  description  that  ex- 
acting interlocking  retiuirements  have  been  met.  No 
operation  can  be  started  until    the    preceding  one    has 


304 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  7 


been  completed.  The  value  of  the  precautions  taken 
is  emphasized  by  the  entire  freedom  from  accidents 
while  handling  cars.  So  perfectly  has  the  interlocking 
been  worked  out  that  the  complete  cycle  of  unloading, 
when  once  started,  may  be  automatic.     All  that  is  nec- 


essary is  for  the  operator  to  put  his  control  handles  in- 
to the  running  position.  If  desired,  he  could  move  all 
handles  at  the  same  time.  The  interlocking  would  as- 
sure correct  functioning  of  all  parts  of  the  equipment 
through  an  unloading  cycle. 


Some  Feni^rf  Ds  ©f  the  Cottrell  Plani  at  tLlie 

■llaydoii  Smelter 


C.  G.   HERSHEY 

Chief  Electrician, 
Havden   Smelter 


THE  Hayden  plant  of  the  American  Smelting  & 
Refining  Co.,  at  Hayden,  Arizona,  is  designed  for 
the  production  of  copper  bullion  from  sulphide 
ores.  In  accordance  with  standard  practice  the  crude 
ore  and  concentrates  are  first  run  through  roasters 
where  they  are  heated  to  a  high  temperature  and  the 
moisture  and  a  portion  of  the  sulphur  content  are  driven 
off.  The  smoke  or  gases  coming  from  the  roasters 
carry  a  considerable  amount  of  solid  matter,  a  portion 
of  which  is  copper.  The  gases  first  pass  through  a  dust 
chamber  where  the  heavier  particles  settle  by  gravity 
and  then  to  the  Cottrell  precipitator.  Here  the  re- 
mainder of  the  solid  matter  is  recovered  by  electrostatic 
precipitation. 


Each  chamber  has  four  groups  or  sections  of  five  pairs 
of  screens  each,  space  being  left  in  each  chamber  for 
two  more  sections  in  case  the  installation  of  additional 
screens  should  prove  to  be  desirable  later  on.  Each 
chamber  is  provided  with  a  damper  at  each  end  and  a 
short  connecting  flue  joins  the  dust  chamber  e.xtension 
to  the  main  flue.  The  top  of  the  chambers  is  covered 
over  by  a  steel  deck. 

The  screens  are  made  of  No.  8  iron  wire  with  a 
2.5  inch  square  mesh  and  are  8.5  feet  wide,  12.5  feet 
long  and  have  a  one  inch  channel  iron  frame.  The 
spacing  between  screens  is  six  inches  and  adjacent  pairs 
are  spaced  twelve  inches.  Baflles  placed  at  the  top  and 
bottom  prevent  the  gases  from  taking'  any  path  other 


FIG.    I — EXTERIOR      VIEW      OF 
TATOR 


FIG.    2 — PRECIPITATOR   AND   CONNECTING 
FLUE 


FIG.    3 — INTERIOR    OF   ONE    CHAMBER    OF 
PRECIPITATOR 


The  Hayden  plant  is  a  radical  departure  from  the 
usual  type  of  Cottrell  precipitator  in  that  the  positive 
electrodes  consist  of  a  series  of  vertical  pairs  of 
grounded  wire  screens  and  the  negative  electrodes  are 
uniformly  spaced  wires  placed  between  each  pair  of 
screens.  The  gas  travels  at  right  angles  to  the  plane 
of  the  screens*. 

In  the  construction  for  the  precipitator  the  old  dust 
chamber  was  extended  sixty-two  feet  and  divided 
longitudionally  into  four  divisions  or  chambers  by  three 
brick  partitions.  Wooden  strips  were  placed  ver- 
tically on  the  walls  which  were  then  gimited  to  a  depth 
of  about  two  inches.  The  strips  were  later  removed 
and  the  screens  slipped  down  into  the  resulting  slots. 

*This  type  of  precipitator  was  developed  by  Mr.  R.  B. 
Rathbiin,  who  designed  the  Hayden  Cottrell  plant  in  detail  and 
supervised  its  installation. 


than  through  the  screens,  and  vertical  spacing  strips 
between  the  screens  avoid  the  possibility  of  their  warp- 
ing out  of  line. 

The  negative  electrodes  are  made  of  No.  14  iron 
wire  and,  for  each  section,  are  held  at  the  top  and 
bottom  by  a  framework  fastened  to  four  vertical 
I-beams  which  pass  through  the  steel  deck  and  are  sup- 
ported by  a  channel-iron  frame  resting  on  four  porce- 
lain insulators.  At  the  point  where  the  I-beams  pass 
through  the  steel  deck  they  are  insulated  by  means  of 
micarta  cylinders,  twelve  inches  in  diameter  and  four- 
teen inches  long,  each  being  provided  with  a  cover 
which  fits  closely  around  the  I-beam  and  keeps  out  cold 
air.  Each  wire  is  kept  in  tension  by  means  of  a  coil 
spring  at  the  bottom.  Approximately  eighteen  wires 
are   uniformly   spaced   between   each   pair  of    screens, 


July,  1 92 1 


THE   ELECTRIC   JOURNAL 


305 


making  a  total  of  three  hundred  and  sixty  wires  to  the 
chamber. 

The  dust  is  shaken  from  the  screens  by  a  system 
of  shaker  bars  which  are  hung  from  the  top  below  the 
steel  deck  and  work  back  and  forth  against  a  striking 
plate  near  the  center  of  each  screen.  For  each  chamber 
the  bars  are  operated  by  a  single  lever.  The  negative 
electrodes  for  each  section  are  shaken  by  a  vertical  rod 


mately  190000  cubic  feet  per  minute.  The  gas  velocity 
in  the  chambers  is  about  eight  feet  per  second,  and  the 
temperature  at  the  entrance  ranges  from  100  to  350  de- 
grees F.,  the  average  temperature  being  about  250  de- 
grees. Ordinarily  the  drop  in  temperature  in  the  treater 
is  about  25  degrees.  The  amount  of  sulphuric  acid  in 
the  dust  ranges  from  0.5  to  40  percent.  The  power 
consumed   per   ton   of   dust   recovered    runs   about   60 


-INTERIOR    OF    RECTIFIER 
BUILDING 


FIG.    5 — RECTIFIER   BUILDING 


FIG.   6 — HIGH     TENSION    ELECTROSTATIC 
VOLTMETER 


so  arranged  that  it  can  be  raised  and  dropped  on  the 
framework  supporting  the  wires.  When  not  being 
operated  it  is  fastened  up  out  of  the  way.  The  dust 
collected  falls  down  into  hoppers  and  is  removed  by 
larry  cars. 

Each  chamber  is  partitioned  off  from  the  others  and 
has  a  high-tension  switch,  operated  by  the  door,  which 
opens  the  circuit  for  that  chamber.  Each  chamber  has 
also  an  automatic  grounding  device,  operated  by  the 
opening  of  the  door,  which  effectually  grounds  the  elec- 
trodes. There  is  also  a  safety  device  which  keeps  the 
door  from  being  accidentally  closed. 

The  electrical  equipment  is  housed  in  a  separate 
building  near  the  precipitator.  There  are  four  15  kv-a 
motor-generator  sets,  four  15  kv-a  transformers  pro- 
vided with  taps  which  give  a  voltage  from  22  500  to 
45  000,  a  motor-driven  exciter,  an  electrostatic  volt- 
meter and  a  switchboard  containing  the  necessary  cir- 
cuit breakers  and  instruments.  The  exciter  capacity  is 
■  such  that  additional  motor-generator  sets  can  be  in- 
stalled later  on.  TJie  rectifiers  are  of  the  well  known 
Lemp  switch  type.  A  28  inch  micarta  disk  carries  the 
revolving  contacts  and  is  mounted  on  a  shaft  extension 
of  the  motor-generator;  the  stationary  contacts  are 
mounted  on  a  micarta  disk  which  is  so  arranged  that  it 
can  be  rotated  through  ninety  degrees.  The  positive 
leads  from  each  rectifier  run  to  a  milliammeter  on  the 
switchboard  and  thence  to  the  ground.  The  negative 
leads  run  to  a  system  of  overhead  buss  wires.  These, 
together  with  hook  connectors,  permit  the  connection 
of  any  section  in  the  treater  to  any  machine. 

The  precipitator  was  designed  to  handle  the  gases 
from  twelve  roasters,  the  total  volume  being  approxi- 


kw-hr.  The  average  working  voltage  is  24  000  volts 
and  the  current  from  the  rectifiers  runs  about  150 
milliamperes.  Under  average  conditions  three  ma- 
chines are  run  at  one  time,  the  fourth  being  reserved  as 
a  spare.  Tests  have  shown  the  recovery  to  be  but 
slightly  less  than  100  percent. 

This  plant  has  been  in  continuous  operation  since 
its  completion  in  January,   1920  and  the  results  have 


FIG.    7 — .\SSEMBLY    OF    POSITIVE    AND    NEG.^TIVE    ELECTRODES 

been  very  gratifying.  It  was  installed  and  is  being  op- 
erated solely  to  recover  the  copper  content  of  the 
roaster  gases  which  otherwise  would  be  lost.  The 
value  of  the  copper  recovered  is  such  that  the  complete 
Cottrell  installation  will  be  paid  for  in  a  relatively  short 
time  and  thereafter  will  yield  a  handsome  dividend  on 
the  investment. 


Tr 831^:0  ik^loB  'M:no  Circuit  CoB^iaiits  aivl 

R.  D.  EVANS  and  H.  K.  SELS 

General  Engineers, 
W'cstinghousc  Electric  &  Mfg.  Company 

THE  PROBLEM  of  obtaining  the  characteristics  A^,,  B„,  C^  and  /?„  for  three  networks  are  as  follows: — 

of   a   transmission   system,   including  transform-  A„  =  Ai  (Ai  A«-\- C\  B^)  -\- B3  (A\  d  +  C\  Dt) (/) 

ers,      frequently     arises.       The     voltage     drop  Bo  =  As  (B^  Ao  +  Di  B.)  +  Bs  (B^  C'.  +  Di /J.) (^) 

through    the    transformer   is    usually    so    large    that    it  r„  =  G  (.-/i  .4s  + /?2  G)  +  A  (-4i  G  +  G  A) (j) 

cannot   be    neglected.     In    general,    the    addition    ot    n 

t.-o.,<-t„.-™»..  *„  „  *  •    •  *  1  .u  The  corresponding  constants  for  two  networks  / 

transtormer  to  a  transmission  system  changes  the  svs-  ^  ° 

,„  ,  „i  .     .  ..  -J      1,1    '  "  'ind  ■^,  are  as  follows: — 

tern  characteristics  considerably. 

The  usual   transmission  problem   involves  a   step-  '  '"'  ~  „ '  ,        „'     ' 

J  ^       J  ,  ,  .     .  "no  =  a\  Ai  -\-  D\  B-2 

up  and  a   step-down   transformer  and   a   transmission  ^^^^  _  ^  C  +  C  D- 

line.     This  problem  may  be  considered  as  one  involv-  /;„,  =  B\  G  -V  0\  A 

ing   three  networks   in   series,   as   indicated   in   Fig.    I  Different  networks  have   different   values   for   the 


.XjiBj,       2 —       Az.Bj,       ^ A|,B 

CD,         CD,        , CD 


The  networks  /,  2  and  .?  have  constants  A,  B,  C  and 
D  suitably  distinguished  by  subscripts.  These  con- 
stants* are  defined  by  the    following  equations : — 

£"j  =  A I  Er  +  B,  I, 

/■2  =  CiEr  +  n,  I, 

Ei  =  A-2  Ei  +  Bi  h 

h  =  G«  Ei-lr  A  h 

E,  =  A3ES+  Bs  h 

I,  =  Ts  A's  -t-  A  h 

Networks   /  and  2  may  be  replaced  by  a  single 

network,  with  constants  determined  by  eliminating  £„ 

and    /„    from    the    first    four    equations    given    above. 

This  process  may  be  repeated  to  replace  the  three  net- 

TABLE  I— CIRCUIT  CONSTANTS  FOR  TYPICAL 
NETWORKS. 


Shunt 

Series 

Transmission 

Admittance 

Impedance 

Lme 

A  =  / 

/ 

cosh  T  ZT' 

B  =  0 

Z 

y\~^i"l>\    ^y 

c=  y. 

0 

^^siuh-i    ZT- 

D  =  I 

1 

cos/i  1  zy 

works  bv  a   single  network.     The   resultant   constants 


*For  a  transmission  line  or  other  symmetrical  system  the 
D  constant  is  equal  to  A.  Thus  for  a  transmission  line  bv  itself, 
the  relations  between  generator  and  receiver  voltages  and  cur- 
rents may  be  expressed  in  terms  of  the  three  constants,  usually 
designated  as  A,  B  and  C,  as  given  by  Mr.  Nesbit  in  his  series 
on  "Electrical  Characteristics  of  Transmission  Circuits"  in  the 
JoURN.AL  for  March  and  April  1920.  The  D  constant  is  emploj'ed 
in  the  accompanying  equations,  so  as  to  provide  for  the  general 
case.  The  use  of  the  D  constant  is  necessary  when  the  trans- 
mission system  is  unsymmetrical  about  its  center;  for  example, 
a  transmission  line  with  dissimilar  transformers  at  each  end. 


•  i,  B,  C,  and  D  constants.  The  characteristics  of 
these  constants  for  three  simple  networks  are  listed  in 
Table  I. ' 

It  is  now  a  simple  matter  to  determine  the  general 
circuit  constants  for  the  case  of  a  transmission  line 
with  step-up  and  step-down  transformers,  as  indicated 
in  Fig.  2,  where  Tr  =  the  receiver  transformer  im- 
pedance, and  Ts  =  the  sending  transformer  imped- 
ance. 

The  network  in  Fig.  2  may  be  considered  as  being 
composed  of  three  simple  networks  in  series,  a  series 
impedance,  a  transmission  line  and  another  series  im- 
pedance with  constants  as  given  in  Table  II. 

From  these  constants,  the  general  circuit  con- 
stants can  be  obtained  by  substitution  in  equations  (i), 
(2),  (3)  and  (4)  and  are  as  follows: — 

TABLE  II.-CIRCUIT  CONSTAXT  FOR  FIG.  2. 


Bx   =    Tr 

C,  =  o 
Dx  =  f 

W,  =  A 
Bi=  B 

'■:=    C 

A  =  A 

A^  =  / 
Bs  =  r, 
a  =  0 

/\  =  / 

Ao  =  A  +  cr 

B„=  B  +  A  ( 

C,  -  C    

(>) 

T,+ 

7\)  +  T,T,C. 

..(6) 

(7) 

A,  =  ^  -1-  CT, 

■  ■(S) 

.■\nother  interesting  case  is  that  of  a  transmission 
line  with  a  shunt  loading  in  the  middle  as  show^n  in 
F'g-  3-  I"  general,  a  capacity  loading  would  be  em- 
ployed, so  as  to  increase  the  amount  of  pow'er  which 
may  be  transmitted  over  the  transmission  lines.  In 
this  case,  the  constants  for  each  netw'ork,  a  transmis- 
sion line,  a  shunt  admittance  and  another  transmission 
line,  are  as  given  in  Table  III. 


July,   1 92 1 


THE  ELECTRIC  JOURNAt. 


From    these    constants,    the    general    circuit    con- 
stants can  be  obtained  by  substitution  in  equations  (i), 
(2),  (3),  (4),  and  are  as  follows: — 
.;„  =  ./-  +  BC  +  BA  }•„, 
Z.'„  ^  2AB  +  R-  )',„ 
U  =  2  AC  +  A-  )■„, 
Z?„  =  A-  +  BC  -t-  BA   )',„ 
If  Fm  in  the  above  formula  is  set  equal  to  zero, 
the  constants  for  a  transmission  line  of  double  length 
are  obtained  in  terms  of   constants   for  single  length. 
TABLE  III— CIRCUIT  CONSTANTS  FOR  FIG.  3. 


./,  =  A 

A,  =  / 

A,  =  .-/ 

Bi  =  B 

B-,  =  0 

/■.3  =  B 

G  =  C 

C2  =   )'„, 

G  =  C 

D,  =  A 

Ih  =  1 

£>s=  A 

When  the  conditions  at  one  end  of  the  transmis- 
sion system  are  known,  the  conditions  at  the  other  end 
can  be  expressed  in  terms  of  the  general  circuit  con- 
stants, with  equations  as  stated  below : — 

E,  =  .-/„  £r  +  B„  /r (9)     E,  =  A,.  /:,  -  A'„  /r (//) 

A    =    Cm  E,   -f   Z>„  Ir (/O)        A    =    -Cn  E,   -f   A.  I,...{l^) 

In  the  first  case,  shown  in  Fig.  2,  for  which  the 
general  circuit  constants  were  developed  above,  it  will 
be  noted  that  the  exciting  kv-a,  has  been  neglected. 
However,  this  can  be  readily  taken  into  account  in  a 
similar  way  by  considering  the  transformer  as  a  par- 
ticular network  and  working  out  the  general  circuit 
constants  accordingly.  Hence,  it  appears  convenient 
to  employ  general  circuit  constants  A^,  B^,  C^  and  /?„ 
for  the  entire  transmission  system,  instead  of  the 
A,  B,  C  constants  for  the  transmission  line  by  itself, 
and  making  separate  calculations  for  each  trans- 
former. 

RESONANCE 

The  practical  cases  from  which  resonance  usuallx' 
arise  involve  a  transmission  line  and  the  transforma- 
ers.  The  resonant  condition  for  the  transmission  line 
by  itself  is  considerably  changed  by  the  addition  of 
transformers.  In  determining  the  conditions  for  re- 
sonance of  a  transmission  system  involving  transform- 
ers, the  desirability  of  employing  general  circuit  con- 
stants will  be  brought  out. 

The  two  resonant  conditions  which  will  be  con- 
sidered are :  — 

Case  I — With  receiver  open. 
Case  II — With  receiver  closed. 


Transmiss 

on  Line 

Transmiss 

on  Line 

t 

S 

-^r- 

Eg 

1    "^ 

0 

,„ 

i 

FIG.  3 

L  ase  I — The  transmission  system  may  be  repre- 
sented by  the  diagram.  Fig.  2.  In  this  case,  the  re- 
ceiver is  open  and  /r  =  0.  The  power  at  the  genera- 
tor is,  from  equations  p  and  lo, — 

E,r,'=    Au~.Er'* 


The  condition  for  resonance  is  that  the  reactive  power 
be  equal  to  zero,  that  is 

(.•^,1  60  -  ~,.  (.'.•)    =  o 

If  the  resistance  and  leakage  resistance  be  neg- 
lected, the  resonant  condition  (as  shown  in  the  appen- 
dix) may  be  stated  as  follow's : — 

1    "^ 


/.!«  , 


r//l     LC    = 


r/Z.  I-      C 

W  here  /.^transmission  line  inductance  per  mile 
C:=transmission  line  capacity  per  mile 
Ls:=step-up  transformer  inductance 
/^resonant  frequency 
/length  of  transmission  line 

In  case  L^  is  zero,  the  condition  for  open  circuit 

resonance    on    a    transmission    system    without    tr.Tn':- 

formers  is  obtained  and  is  as  follows  ■ — 

/ii>i  -^  TT  /  /  I   TTZ'  =  CO 

Hence,  ^  ir J  I  \    LC  =  it  -^  2 
I 

^  "7/1  TTc 
It  is  to  be  noted  that  the  shortest  length  of  line 
for  resonance,  which  is  the  quarter  wave  lengtfi,  cor- 
responds to  an  angle  in  the  first  quadrant,  as  is  de- 
noted by  the  positive  sign.  For  any  positive  value  of 
Z-s  it  is  obvious  that  the  tangent  of  the  angle  must  be 
less  than  infinity,  and  hence  the  angle  is  less  thafi  one- 
half  -K. 

Case  II — The  transmission  system  may  be  repre- 
sented by  the  diagram  shown  in  Fig.  4.  For  this  con- 
dition, E^  ^  0  and  the  generator  power  is,- — 

/r«  7  =  /?„  A,  (A  A) 
The  condition  for  resonance  is  that  the  reactive  power 
be  equal  to  zero  which  is, — 

(/.',.  ~  -   ~  /)„)    =  o 

If  the  resistance  and  leakage  resistance  be  neg- 
lected, the  resonant  condition,  as  shown  in  the  appen- 
di.x,  may  be  stated  as  follows: — 

-  •?  T/"  (L,  +  L.) 

/  I  1 


tan  . 


1.  C  = 


Where  the  notation  is  the  same  as  given  in  Case  I 
and  with  L^  equal  to  the  receiver  transformer  induct- 
ance. In  case  the  transmission  line  is  short-circuited 
at  either  end,  so  that  only  one  transformer  is  included 
the  resonance  condition  is  obtained  by  simplifying  the 


*\\here  Is  and  Co  are  conjugates  of  L  and  Ci..  The  conju- 
gates of  any  vector  quantity  are  obtained  by  changing  the  sign 
of  the  y  term. 


FIG.  4 

above   formulas  and  setting  either  L^  or  L^  equal   to- 
zero.     The  condition  for  closed  circuit  resonance  of  a 
transmission  line  by  itself  is  obtained  by  setting  both 
Ly  and  L^  equal  to  zero,  which  gives, — 
tan  2  TT  f  I  \    LC  =  —  o 
hence  2  ir  f  I  \' TC  =  /So"  =  w 
I 

2  I  \  Tc 


3o8 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


It  is  to  be  noted  that  the  shortest  length  of  line 
for  resonance,  which  is  the  half  wave  length,  corre- 
sponds to  an  angle  in  the  second  quadrant  when  the 
tangent  is  negative,  and  in  the  first  when  it  is  positive. 
Values   in   the   first  quadrant  are  possible  only   when 


1.60 

E 

|aoo 

-180 

.inet 

- 

— 



iSU 

rittiC 

_ 

tor  T;  ansfotmsra 

- 

^ 

^ 

EfteaWe 

Spacing  in 

pj 

3etw 

S6o     ;     lopo 

en  E   rlh  Current  and 

Line] 

FIG.  5 — RESONANXE  Al   l8o  CYCI.KS  OF  A  TRANSMISSION  SYSTEM 

Without  ground  wire  and  with  receiver  open,  as  shown  in  Fig.  2. 
Lr  and  L^  are  large  enough  to  make  the  denominator 
of  the  fraction  in  the  general  equation  negative. 

RESONANCE    CALCULATION    FOR   A    PARTICULAR   SYSTEM 

In  order  to  show  what  effect  transformer  imped- 
ance has  on  resonance,  a  220  kv,  three-phase,  60  cycle, 
250  mile  transmission  line  will  be  considered,  with 
500000  circ.  mil  copper  conductors,  with  21  ft. 
equivalent  spacing  at  an  average  height  of  50  ft.  above 
ground,  with  a  50000  kv-a  bank  of  10  percent  react- 
ance transformers  at  each  end. 

The  natural  frequency  for  each  condition  as 
shown  in  Table  IV  is  obtained  by  calculating  the  con- 
stants and  substituting  in  the  equations  given  above. 

The  above  conditions  for  resonance  have  been 
considered  for  a  polyphase  system.  With  a  grounded 
neutral  system  there  is  the  condition  for  resonance  as 
a  single-phase  system,  with  the  transmission  wires  as 
one  side  of  the  circuit  and  the  earth  as  the  return.  In 
case  the  transmission  line  is  equipped  with  a  ground 
wire,  the  return  current  may  flow  through  the  ground 
wire  and  through  the  earth,  depending  on  the  relative 
admittance  of  these  paths.  The  formulas  given  above 
apply  to  these  conditions,  but  the  constants  must  be 
derived  with  reference  to  the  actual  path  which  the 
current  takes.  The  constants  of  the  circuit  with 
ground  wire  returns  may  be   calculated  in   the  usual 

TABLE  IV— NATURAL  FREQUENCY  OF  THREE- 
PHASE,  60  CYCLE  TRANSMISSION  LINE 


.                                  1    Resonant  Frequency 
Condition                                             ,       ,        „        ,_ 
Case  I              Case  II 

181 
158 

362 
318 
282 

Line  and  generator  transformer. . 
Line  and  both  transformers 

way.  The  circuit  constants  with  earth  return  depend 
on  the  effective  position  of  the  earth  current  which  is 
probably  between  the  image  of  the  conductors  and 
5000  feet  below. 

A  grounded  neutral  system  permits  the  flow  of 
triple  frequency  currents.  Triple  frequencj^  voltages 
are  produced  by  the  magnetizing  currents  of  certain 
transformer  construction  and  connections,  such  as 
star-star,  two  coil,  or  autotransformers.  On  this  ac- 
count, it  is  desirable  to  show  the  condition  for  reson- 
ance   at    180    cycles.     The    inductance    of    the    trans- 


former is  that  which  results  when  the  line  terminals 
are  connected  to  one  side  of  the  circuit  and  the  neutral 
to  the  other  side.  In  the  curves,  shown  in  Figs.  5  and 
6,  for  the  resonance  of  a  transmission  system  without 
ground  wire,  the  inductance  of  the  earth  return  has 
been  considered  as  zero.  In  these  curves,  the  length 
of  the  transmission  line  in  miles  is  plotted  against  the 
position  of  the  return  current,  expressed  in  feet  below 
the  transmission  wires. 

The  important  cases  to  be  considered  are  the  open 
circuit  transmission  line  with  generator  transformer, 
and  the  closed  circuit  transmission  line  with  both  gen- 
erator and  receiver  transformers.  Perhaps  it  should 
be  pointed  out  that  a  transmission  line,  employing 
transformers  with  grounded  neutral  at  each  end,  pro- 
vides a  closed  circuit  for  triple  frequency,  and  the  re- 
sonant condition  is  the  normal  operating  condition,  if 
the  line  is  of  sufficient  length.  In  case  of  resonance, 
the  current  flowing  is  dependent  on  the  voltage  and  re- 
sistance of  the  circuit.  The  maximum  voltage  on  the 
transmission  line  may  be  calculated  in  the  usual  way 


gffectii[e  Spi  cing  i  n  Fee :  Be^  f een  garth  .b  urr^t  antf  Lin^ 


FIG.    6 — RESON.\NCE  AT    l8o  CYCLES   OF   TRANSMISSION    LINE,   FIG.   4, 
WITH    RECEIVER   CLOSED 

from  the  voltage  and  current  at  one  end.  Dangerous 
triple  frequency  voltages  may  be  avoided  by  employ- 
ing a  tertiary  winding  of  suitable  design,  or  by  the  use 
of  an  auxiliarj'  transformer  with  delta  connections  to 
reduce  the  triple  frequency  voltage  produced  by  the 
magnetizing  currents. 

APPENDIX 

The  resonance  formulas  may  be  simplified  by  neg- 
lecting  resistance   and   leakage   conductance,   as   indi- 
cated below: — 
A  =  cosh  y  ZT'  =  cosh  2  -n  f  I  \    -LC  =  cos  tt  f  t  ■\   LC  =  A 


\^ 


sin/i  V  y.y=  aI^"'"''  -  '^/'  1'  ~^^  ~ 


\-c 


^■^\  z  ''"^'y^^- 


+  J   v'-g^y'"  •?  ^/l  ]    LC  = 
siii/i  2  Tt f  I  1    —LC  = 


+  j- 


fl\    LC  = 


D  =  A  =  D 
T,=  +J2^/L, 
■n  =  +J2ir  fL, 

Where  Z-r  =  receiver  transformer  inductance 
and  jLs  =  generator  transformer  inductance 


July,  1921 


THE  ELECTRIC  JOURNAi^ 


309 


Case  I — The  condition  for  resonance  is  that, — 


(B„  /;„  -  /;„  A)   =  o 


For  the  network  shown  in  Fig.  4,  the  constants  given  above 
^         ,  .         1      ,  •      T-  ii  i      ^       •  with  Ti=z-\-J2Tr  fL,  for  the  closed  circuit  receiver,  may  be  sub- 

For  the  network  shown  in  Fig.  2,  the  constants  given      .tituted   in  the  above  equation,  which  gives,   when   simplified, 
in  equations  5  to  8,  with  T^  =  0  for  open  circuit  re-      the  following  expression:— 
ceiver,  may  be  substituted  in  the  above  equation,  which 
gives   when   simphfied  the   following  expression : — 


[  +./  J-|-  ."■»  -'  t//  I    LC  +J.'  tt/  {L,  +  L,)c-os2-,r//  I    LC 


J  \ios  2  irfl  I    LC  -  -J—  {sin  2  tt//  V  LC)  2  -w  f  l'\ 


+  j  Lr  L,  {2  n/)  2^1  ^  sin  21^  fly  LC^  X 


cos  2  nfl  1    LC 


\- 


{sin  2  Trfl  1    LC)  2  ^fL, 


\- 


tan  2  -K  f  ly  LC 


1     ^ 


2TrfL^\     C 

Case  II — The  condition  for  resonance  is  that- 


./        ry.,              -2-.f{Lr  +  L,) 
tam-rf  I  V  LL  =  — ; ^; 

I  C 

\7 


^^-{2./VL,L.J^ 


iracterlstks  ©f  Syaiciir 
Motors 


E,  B    SHAND 


UNTIL  synchronous  speed  is  reached  no  steady 
torque  is  exerted  by  a  synchronous  motor,*  con- 
sequently the  rotor  is  provided  with  a  squirrel- 
cage  or  damper  winding  similar  to  that  of  an  induction 
motor,  which  is  relied  upon  to  accelerate  it 
nearly  to  synchronous  speed.  The  complete  starting 
operation  includes  all  phenomena  from  the  time  of  the 
first  application  of  voltage  to  the  time  when  steady 
operating  conditions  are  reached.  This  comprises 
starting  from  rest  and  accelerating  on  reduced  voltage, 
the  applying  of  the  excitation  and  the  subsequent 
synchronizing  of  the  motor,  and  the  final  transition 
to  full  running  voltage.  This  order  may  not  be  strictly 
followed  in  certain  cases — when,  for  instance,  a  motor 
will  synchronize  without  excitation,  or  when  it  will 
either  not  start  or  not  synchronize  on  reduced  voltage — 
but  probably  in  the  greater  number  of  cases  this  repre- 
sents the  sequence  of  operation. 

On  applying  voltage  to  the  armature  winding  with 
the  machine  at  rest  it  is  considered  necessary  either 
to  close  the  field  winding  through  a  resistance,  or  to 
sectionalize  it  by  means  of  a  break-up  switch,  to  pro- 
tect its  insulation  from  the  abnormal  voltages  generated 
in  it  before  the  rotor  has  approached  its  synchronous 
speed.  As  the  latter  arrangement  is  not  applicable  to 
rotating  field  structures,  the  former  scheme  is  generally 
used,  although  the  details  may  depend  somewhat  upon 
the  source  of  excitation  employed.  When  the  motor 
is  excited  from  a  direct-current  bus  the  usual  prac- 
tice is  to  short-circuit  the  field  winding  with  the  nor- 
mal rheostat  resistance  still  in  the  circuit.  As  soon 
as  the  rotor  approaches  synchronous  speed,  the  field 
switch  is  thrown  over  to  the  direct-current  bus. 
When  the  motor  is  furnished  with  a  direct-connected 
exciter,  the  same  arrangement  may  be  used,  but  it  is 


more  usual  simply  to  leave  the  field  connected  directly 
across  the  exciter  armature  throughout  the  whole  of 
the  starting  period.  The  exciter  voltage  rises  roughly 
with  the  square  of  the  speed,  so  that  until  a  fairly  high 
speed  is  reached  the  exciting  current  is  negligeable. 
In  this  way  a  greater  simplicity  is  realized  and  the 
scheme  operates  very  satisfactorily. 

The  torque  exerted  during  the  first  period  of  the 
starting  operation  may  be  considered  as  the  combina- 
tion of  three  separate  torques,  all  resulting  from  in- 
duction motor  action  in  different  secondary  circuits 
in  the  rotor.  First,  there  is  a  torque  developed  in 
the  squirrel-cage  winding.  This  winding,  when  con- 
nected continuously  from  pole  to  pole,  forms  a  rela- 
tively complete  polyphase  secondary,  and  its  speed- 
torque  curve  is  similar  to  that  of  an  induction  motor. 
By  selecting  the  material  and  section  of  the  bars  em- 
bedded in  the  pole-faces,  the  form  of  the  speed-torque 
curve  may  be  controlled  to  cause  the  pull-out 
torque  to  be  exerted  at  any  given  speed  within  certain 
limits.  In  the  curves  of  Fig.  8,  which  are  plotted 
from  test  results,  this  feature  is  clearly  defined.  In 
the  second  place,  there  is  a  torque  due  to  eddy  currents 
in  the  rotor  and  pole  bodies.  These  currents  flow 
mostly  in  the  pole  faces  and  in  paths  formed  by  the 
pole  rivets.  The  paths  have  the  effect  of  a  high  re- 
sistance damper  winding  not  interconnected  between 
poles.  In  addition,  although  not  a  true  induction  motor 
torque,  there  is  a  hysteresis  torque  which  is  produced 
by  this  iron  loss  of  the  rotor.  The  torque  is  small 
and  constant  in  value.  The  third  torque  is  produced 
by  the  closed  field  winding  acting  as  a  single-phase 
secondary.  It  is  a  characteristic  tendency  for  the 
torque  of  a  single-phase  secondar\-  to  be  reversed  above 
one-half  synchronous  speed.* 


..!7!"^^^'''='^  ^^""''^  ^^  ""^^^  in  conjunction  with  the  article  *See     "Polvphase     Induction     Motor     with     Single-Phase 

oil     Principles  and  Characteristics  of  Synchronous  Motors"  by      Secondary"  bv  B.   G.  Lamme  in  the  Journal  for  Sept.,   101=;, 
the  author  in  the  Journal  for  March.  1921,  p.  87.  p.  394. 


3IO 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  Xo.  7 


Therefore,  above  half  speed  the  torque  of  the  field 
winding  i.-;  liaMc  to  be  negligeable  factor,  although  be- 
low this  speid  its  effect  is  positive  in  direction.  The 
curves.  Fig.  8  show  that  the  torque  produced  by  the 
closed  field  winding  is  materially  reduced  above  one- 
half  synchronous  speed.  These  tests  were  not  carried 
below  this  speed  with  the  field  open;  however,  the  re- 
sults of  other  tests  on  the  torque  at  standstill  of  a 


90C 

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FIG.  8— SPEBB-TORQUE  CURVES  OF  A  225  HP  SYNCHRONOUS  MOTOR 

Taken  at  approximately  one  half  voltage. 

similar  motor  under  the  same  conditions  are  shown 
in  Fig.  10.  These  curves  show  that  the  torque  is 
reduced  considerably  when  the  field  winding  is  closed, 
even  though  it  produces  a  torque  of  positive  direction. 
The  reason  for  this  reduction  of  torque  may  be  stated 
somewhat  as  follows: — When  the  field  circuit  is  closed 
it,  being  of  low  resistance,  will  tend  to  choke  back 
the  fluxes  interlinking  the  damper  winding,  i.  e.  the 
useful  flux.  This  shows  itself  as  an  increased  com- 
ponent of  primary  reactive  current  and  leakage  flux. 
The  torque  produced  by  the  main  damper  winding 
will  consequently  be  reduced  to  such  an  extent  that 
the  relatively  small  torque  exerted  by  the  field  wind- 
ing will  fail  to  compensate  for  this  reduction.  Thus, 
the  net  result  is  a  decrease  of  the  total  torque  of  the 
rotor. 

The  same  effect  also  results  from  the  use  of  com- 
pound damper  windings,  but  to  a  lesser  degree.  By 
compound  damper  windings  is  meant  two  sets  of  bars, 
or  bars  and  end  rings,  on  the  same  rotor,  each  set 
having  a  different  resistance  and  reactance.  In  de- 
signing these  windings,  therefore,  as  in  the  case  of  a 
simple  damper  winding  a  compromise  must  be  made; 
in  the  former  case,  to  give  the  greatest  variation  of 
effective  rotor  resistance  without  increasing  the  leak- 
age reactance  too  much;  and  in  the  latter  case  to  pro- 
portion the  effective  rotor  resistance  to  give  the  high- 
est torque  both  at  starting  from  resr  and  near 
synchronism. 

Unless  the  load  torque  be  too  great,  the  combined 
induction  torque  should  accelerate  the  rotor  to  with- 
in perhaps  five  percent  of  synchronous  speed,  where 
the  rotor  will  remain  and  thus  complete  the  first  phase 
of  the  starting  operation.  Occasionally  when  a  motor 
has  reached  this  stage  it    will    make   the    transition    to 


synchronous  operation  without  any  further  external 
adjustment,  although  ordinarily  it  is  necessary  to  apply 
the  field  excitation  because  this  will  assist  considerably 
in  pulling  the  rotor  into  step.  The  torque  exerted  by 
the  excitation  fluctuates.  It  may  be  resolved  into  two 
components,  one  steady  and  the  other  alternating. 
The  first  may  be  explained  by  assuming  the  excited 
rotor  to  be  driven  by  an  external  means  from  rest  , 
to  synchronous  speed.  Thus  the  machine  will  be  essen- 
tially a  generator,  inducing  an  e.  m.  f.  in  the  arma- 
ture winding,  in  proportion  to  its  speed,  which  circu- 
lates a  current  at  a  corresponding  frequency  in  the  ex- 
ternal circuit  composed  of  transformers,  supply  lines 
and  finally  the  windings  of  the  actual  generator  at 
the  other  extremity  of  the  line.  This  current  will  flow 
mdependently  of  the  current  of  the  impressed  fequency, 
or  what  might  be  considered  the  driving  current,  but 
the  two  currents,  when  combined,  will  produce  a  sin- 
gle current  which  fluctuates  in  value  at  slip  rrequency. 
The  magnitude  of  the  fluctuation  depends  upon  the 
amount  of  excitation.  Under  some  conditions'  this 
phenomenon  may  be  observed  from  the  beating  of  the 
needle  of  the  line  ammeter.  The  torque  produced  by 
this  generator  action  is  represented  by  curve  IT  m 
Fig.  9.  It  is  always  a  retarding  torque  and,  near 
synchronous  speed,  may  be  regarded  as  practically  con- 
stant in  magnitude.  An  actual  case  has  been  recorded 
vihere  a  motor  started  under  a  heavy  load  and  came 
up  to  within  5.5  percent  of  synchronous  speed  but  would 
not  synchronize;  when  approximately  full  excitation 
was  applied  the  slip  increased  to  12.3  percent,  due  to 
the  retarding  torque;  which  instance  shows  that  in 
some  cases,  at  least,  this  effect  will  produce  quite  ap- 
preciable results. 

The  other  component  of  torque  due  to  excitation 
is  that  of  ordinary  synchronous  action;  that  is,  it   ^s 


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FIG.  9— STARTING  CLRVES  OF  A  SYNCHRONOUS  MOTOR 

the  result  of  the  relative  displacement  between  the 
rotor  and  the  revolving  armature  field  at  any  particu- 
lar instant,  according  to  the  relationships  expressed 
graphically  by  Fig.  3*.  Throughout  one-half  the  cycle 
of  slip,  the  torque  is  positive,  tending  to  keep  the 
rotor  in  step,  while  throughout  the  next  it  is  negative, 
tending  to  make  the  rotor  slip  behind  at  a  still  faster 


*In  the  Journal  for  March,  '21,  p. 


July,  1921 


THE  ELECTRIC  JOURNAl. 


3" 


rate.  Such  a  torque  will  set  up  forced  oscillations  of 
the  rotor  about  the  mean  speed  resulting  from  the 
combined  steady  torques,  and  these  oscillations  would 
continue  indefinitely  were  it  not  for  the  fact  that  the 
alternating  torque,  when  strong  enough,  will  hold  the 
rotor  completely  in  step  on  one  of  its  upward  swings, 


FIG.    10 — TORQUES   AT   STANDSTILL  OF  250   HP,  60  CYCLES,  44Q  VOLT, 
600   R.    P.    M.    SYNCHRONOUS   MOTOR 

whereupon  the  mean  speed  becomes  synchronous  speed. 
The  alternating  torque  is  a  function  of  the  excitation, 
which  is  also  expressed  by  Fig.  3.  The  actual  value 
required  to  pull  the  rotor  into  step  depends  upon  sev- 
eral factors,  such  as  the  retarding  torque  of  the  ap- 
plied load,  and  also  the  relation  between  the  period 
of  slip  frequency  and  the  inertia  of  the  rotating  masses. 
This  latter  point  may  be  considered  as  follows : — The 
positive  part  of  the  torque  acts  in  a  series  of  impulses 
with  a  duration  of  one-half  the  period  of  slip  fre- 
quency. For  these  impulses  to  pull  the  rotor  into  step, 
the  retarding  torque  must  be  overcome  and,  in  addi- 
tion, an  excess  torque  must  be  exerted  to  accelerate 
the  rotating  masses  to  synchronous  speed  in  the  half- 
period,  or  the  duration  of  one  of  the  positive  impulses. 
Referring  to  Fig.  11,  the  synchronous  torque  curve 
for  various  rotor  displacements  is  similar  to  those  of 
Fig.  3.  The  difference  between  the  load  torque  and 
the  synchronous  torque  is  that  available  for  the  ac- 
celeration of  the  rotor  and  load.  The  longer  the 
period  of  slip  frequency,  or  the  less  the  inertia  of  the 
masses,  the  greater  will  be  the  increase  of  speed  be- 
fore the  accelerating  torque  of  a  single  impulse  has 
fallen  to  zero.  If  the  rotor  has  not  been  accelerated 
to  synchronous  speed  before  the  displacement  x  is 
reached,  the  rotor  will  not  synchronize  and  either  the 
excitation  or  the  applied  voltage  must  be  raised  to  in- 
crease the  torque.  If,  however,  as  in  Fig.  11,  syn- 
chronous speed  is  reached  at  the  displacement  y,  or 
less,  the  rotor  will  accelerate  beyond  synchronous  speed 
momentarily  and  the  forced  oscillations  of  continuous 
slip  will  be  replaced  by  free  oscillations  which,  when 


damped  out,  leave  the  rotor  at  the  point  2  and  oper- 
ating under  stable  synchronous  conditions.  The  lower 
curve  of  Fig.  11  represents,  with  a  simple  assump- 
tions, the  relation  between  angular  position  and  speed 
of  the  rotor  when  the  latter  synchronizes.  It  shows 
the  oscillations  of  speed  and  displacement  before  the 
motor  finally  settles  as  at  synchronous  speed. 

The  synchronous  torque  due  to  the  non-uniformi- 
ty of  the  air-gap  in  salient-pole  machines  also  exerts 
a  torque  assisting  in  the  process  of  synchronizing,  but 
as  the  actual  value  is  ordinarily  less  than,  and  its 
duration  only  one-half  that  of  the  excitation  torque, 
its  effectiveness  is  much  less  and  will  actually  perform 
the  operation  of  synchronizing  only  in  exceptional  cases 
where  the  load  and  inertia  are  small. 

The  third  step  of  the  starting  operation  consists 
in  changing  over  from  the  reduced  starting  voltage 
to  the  running  voltage.  The  former  varies  from  about  30 
to  70  percent  of  the  latter,  and  is  obtained  either  by 
means  of  autotransformers  used  only  for  the  purpose 
of  starting;  or,  where  a  step-down  transformer  is  re- 
quired between  the  line  and  the  motor,  from  starting 
taps. 

When  the  starting  switch  is  thrown  from  the  start- 
ing position  to  the  running  position  surges  are  almost 
inevitable.  The  case  is  somewhat  similar  to  the  syn- 
chronizing of  two  alternators,  but  has  the  disadvantage 
that  the  voltage  and  phase  conditions  of  the  motor 
are  not  under  direct  control  at  the  instant  of  synchron- 
izing, hence  the  resulting  surges.  The  most  serious 
surge  ordinarily  occurs  at  the  instant  of  closing  of  the 


FIG.    II — SPEED   AND   DISPLACEMENT   OSCILLATION   OF    SYNCHRONOUS 
MOTOR  AT  TRANSITION   TO   SYNCHRONOUS   OPERATION 

switch,  due  to  an  instantaneous  difference  between  the 
voltage  of  the  motor  terminals  and  of  the  line,  although 
there  will  probably  be  subsequent  disturbances  as  the 
load  is  assumed  again  by  the  supply  system. 

As  already  stated,  the  equivalent  flux  of  a  motor 
is  directly  proportional  to  the  applied  voltage,  so  that 


312 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


if  the  voltage  be  increased  from  30  to  100  percent  or 
from  70  to  100  percent,  the  flux  must  change  in  the  same 
proportions.  If  the  transition  from  one  condition  to 
the  other  were  instantaneous,  the  resulting  surges  might 
be  expected  to  be  proportional  to  the  increase  of  volt- 
age. As  a  matter  of  fact,  however,  this  is  not  neces- 
sarily true.  In  the  case  of  small  synchronous  motors, 
the  type  of  switching  used  allows  a  period  of  four  or  five 
cycles  during  which  the  connection  between  the  motor 
and  the  line  is  entirely  interrupted,  although  the  tran- 
sient conditions  proceed  in  the  motor.  If,  for  instance, 
the  motor  be  considerably  over-excited  when  operating 
on  the  reduced  voltage,  the  normal  flux  correspond- 
ing to  this  excitation  will  have  been  decreased  by  de- 
magnetizing armature  currents ;  but  when  these  disap- 
pear on  the  interruption  of  the  circuit,  the  flux  will 
immediately  begin  to  rise  at  a  rate  controlled  by  the 
damping  effect  of  the  rotor  circuits,  and  the  armature 
terminal  voltage  will  rise  correspondingly.  This  prin- 
ciple can  be,  and  is,  utilized  to  bring  up  the  terminal 
voltage  of  the  motor  to  meet  that  of  the  incoming 
line.  The  period  of  interruption  is  not  long  enough 
to  allow  the  flux,  and  the  voltage,  to  rise  to  wtiat  would 
otherwise  be  their  final  values,  therefore,  to  reach  the 
line  voltage  in  the  allotted  time,  the  excitation  must 
be  set  for  an  open-circuit  voltage  considerably  in  ex- 
cess of  the  line  voltage.  If,  for  instance,  the  change- 
over be  from  iioo  volts  to  2200  volts  the  excitation 
should  be  set  for  an  open-circuit  voltage  of  perhaps 
3000,  which  might  bring  the  terminal  voltage  of  the 
motor  to  about  2200  volts  as  the  switch  is  closed  on  the 
line  side,  and  thus  reduce  the  surge  to  a  minimum. 
The  actual  value  of  excitation  required  for  any  par- 
ticular case  must  be  determined  experimentally,  al- 
though some  such  ratio  as  that  indicated  above  may  give 
quite  satisfactory  results. 

When  the  change-over  is  made  with  an  appreciable 
load  on  the  motor,  the  rotor  will  have  taken  up  a  cer- 
tain backward  phase  displacement  with  respect  to  the 
revolving  field  when  operating  on  the  reduced  voltage. 
On  this  account  there  will  be  a  difference  of  phase 
angle  between  the  motor  and  line  voltages  when  they 
are  synchronized.  The  surge  due  to  this  cause 'can- 
not be  reduced  materially  by  adjusting  the  field  cur- 
rent. 

The  first  surge  produced  by  an  instantaneous  dif- 
ference of  voltage  will  die  away  very  quickly.  If 
the  motor  be  loaded,  however,  there  will  be  additional 
surges  involving  the  inertia  effects  of  the  rotor  as  it 
oscillates  in  coming  to  a  new  phase  displacement. 
This  surge  will  persist  for  a  much  longer  period,  and 
is  the  one  ordinarily  observed  from  the  swinging  of 
the  line  ammeter  needle. 

Fig.  12*  represents  test  data  on  the  relation  be- 
tween the  maximum  armature  current  reached  on 
change-over,  expressed  as  a  function  of  the  field  cur- 


rent. It  will  be  observed  that  the  field  current  is  an 
important  factor  in  determining  the  severity  of  the 
surge. 

When  large  motors  are  started,  involving  heavier 
circuit-breaking  apparatus,  the  transition  period  may 
last  a  second  or  more.  A  motor  cannot  be  completely 
taken  off  the  line  for  this  period  without  producing 
excessive  surges.  Therefore,  to  overcome  the  difficulty, 
the  circuit  is  not  completely  opened,  but  the  voltage 
is  still  maintained  through  resistances  or  reactances 
which,  in  the  latter  case,  may  be  a  part  of  the  starting 
transformer  winding.  This  arrangement  does  noi 
necessarily  result  in  surges  that  are  correspondingly 
less  than  in  the  case  of  the  simple  starting  arrange- 
ment when  used  with  the   smaller  motors  and,  as  a 


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*From    "The    Behavior    of    Synchronous    Motors    during 
starting" — F.  D.  Xewbury,  A.  I.  E.  E.,  June  1913. 


FIG.     12— RELATION    BETWEEN    ARMATURE    CURRENTS    AND    FIELD 

CURRENTS   OF   20O  KV-A,  6o   CYCLE,   24OO  VOLT,   SYNCHRONOUS 

CONDENSER 

Maximum   armature   current   reached   on   change-over  ex- 
pressed as  a  function  of  the  field  current. 

matter  of  fact,  may  produce  greater  surges  because  the 
\oltage  maintained  on  the  machine  prevents  the  arma- 
ture voltage  from  rising  during  transition.  It  is,  how- 
ever, necessary  for  the  larger  machines,  and  lends  it- 
self readily  to  automatic  starting  control  as  well. 

As  the  synchronous  motor  is  started  on  the  induc- 
tion motor  principle  its  characteristics  during  the  start- 
ing period  may  naturally  be  compared  with  those  of 
the  induction  motor.  In  turning  to  the  design  pro- 
portions of  these  two  types  of  machines,  it  will  first 
be  noted  that  the  air-gap  of  the  induction  motor  is 
much  shorter  and  its  number  of  slots  is  greater  than 
that  of  the  slots  of  a  synchronous  motor.  The  induc- 
tion motor  air-gap  is  made  short  to  reduce  the  mag- 
netizing current  as  much   as  possible,  so  that  a  high 


July,   1921 


THE  ELECTRIC  JOURNAL 


313 


power  factor  may  be  maintained.  On  the  other  hand, 
the  air-gap  of  a  synchronous  motor,  is  made  wide 
enough  to  ensure  inherent  stability  of  operation  under 
heavy  loads.  On  starting,  the  result  is  that  the  syn- 
chronous motor  draws  a  heavy  magnetizing  current 
and  thus  requires  an  increased  kv-a  input  for  a  given 
voltage.  Those  phases  magnetizing  the  inter-polar 
spaces  will  show  especially  heavy  magnetizing  currents. 
Another  effect  of  the  wider  air-gap  is  the  increase 
of  leakage  reactance.     The  importance  of  this  factor 

TABLE  I— COMPARISON  OP  TORQUES  AND  KV-A  AT 
STANDSTILL  FOR  100  PERCENT  VOLTAGE 


Per- 

Per- 

Per- 

cent 

cent 

cent 

R.P. 

Power- 

Rated 

Rated 

H.P. 

M. 

Factor  Torque 

Kv-a 

Slip-ring  Induction  Motor    

300 

900 

200 

350 

Squirrel-Cage  Induction  Motor    .  . 

300 

900 

125 

675 

Salient  Pole  Synchronous  Motor   . 

300 

900 

100 

175 

750 

Salient  Pole  Synchronous  Motor  . 

300 

900 

80 

200 

700 

Slip-ring  Induction  Motor    

300 

300 

140 

220 

Squirrel-Cage  Induction   Motor    .  . 

300 

300 

100 

425 

Salient  Pole  Synchronous  Motor.  . 

300 

300 

100 

90 

375 

Salient  Pole    Synchronous   Motor. 

300 

300 

80 

100 

350 

upon  the  torque  is  shown  by  the  fact  that  the  pull- 
out  torque  varies  inversely  as  the  leakage  reactance. 
There  are  other  causes  of  increased  leakage  in  the  syn- 
chronous motor;  for  instance,  the  concentration  of  the 
damper  bars  in  the  pole  face  and  the  decreased  num- 
ber of  armature  slots  below  what  is  considered  a 
minimum  for  good  induction  motor  design.  This  is 
especially  true  for  machines  with  a  large  number  of 
poles,  i.  e.,  slow-speed  motors.     In  addition,  as  already 


mentioned,  the  closed  held  winding  will  increase  the 
leakage  reactance  considerably,  although  the  extra 
torque  developed  by  it  is  small. 

On  comparing  the  synchronous  motor  with  the 
squirrel-cage  type  of  induction  motor,  the  former  has 
one  distinct  advantage ;  the  damper  winding  can  be  de- 
signed from  the  standpoint  of  torque  requirements 
alone.  In  the  case  of  the  squirrel-cage  induction  mo- 
tor, the  rotor  losses  at  full  load  must  be  reduced  to 
give  high  efficiency,  so  that  a  part  of  the  torque  .nt 
standstill  must  be  sacrificed  to  obtain  this. 

The  whole  matter  may  be  summed  up  by  stating 
that,  for  starting,  the  synchronous  motor  is  an  imper- 
fect form  of  induction  motor,  drawing  heavy  magnetiz- 
ing currents  and  having  a  comparatively  high  leak- 
age reactance.  On  the  other  hand,  its  winding,  be- 
ing designed  for  maximum  torque  regardless  of  ef- 
ficiency, utilizes  the  remaining  possibilities  to  the  ut- 
most, so  that  the  actual  torque  becomes  quite  com- 
parable to  that  of  the  induction  motor,  although  the 
kv-a  input  is  rather  greater.  To  make  this  more  defi- 
nite, the  values  of  torque  and  kv-a  at  rest  are  given  in 
Table  I,  for  corresponding  motors  at  two  different 
speeds.  The  falling  off  of  torque  for  the  slower  speed 
motors  is  indicated  by  this  table.  The  Table  indicates, 
moreover,  that  the  ratio  of  torque  to  the  kv-a  is  high- 
er for  the  synchronous  motor  than  for  the  squirrel- 
cage  induction  motor.  This  is  the  result  of  the  de- 
sign concessions  just  referred  to. 


Cj 


eaaing  Siirfaco  ConilDiisLM 


rsp 


1 1  (i)a^ 


D.  W.  R.  MORGAN 

Condenser  Engineering  Dept., 
Wcstinghouse  Electric  &  Mfg.  Company 


MAINTAINING  clean  condensers  is  one  of  the 
most  important  items  in  the  economical  opera- 
tion of  the  steam  power  plant.  The  best 
method  to  clean  the  condensers  with  a  minimum  ex- 
penditure is  carefully  studied  by  the  larger  power  sta- 
tions but  is  not,  generally  speaking,  given  proper  con- 
sideration by  stations  having  a  relatively  small  output, 
probably  due  to  the  fact  that,  in  such  plants,  less  at- 
tention is  paid  to  overall  plant  efficiency. 

The  degree  of  cleanliness  at  which  the  condenser 
is  maintained,  not  only  affects  the  B.t.u.  heat  trans- 
fer, which  directly  affects  the  vacuum,  but  also  has  a 
marked  eft'ect  on  the  life  of  the  tubes.  The  increased 
operating  expense  incurred,  due  to  a  discrepancy  of 
0.1  inch  vacuum  is  given  in  Fig.  i.  This  curve  shows 
the  increased  cost  of  operation  at  different  loads,  us- 
ing a  25  000  kw  unit  as  a  basis,  and  assuming  the  cost 
of  coal  at  $6.09  per  gross  ton.  The  curves  in  Fig  2. 
denotes  the  performance  obtained  after  the  con- 
denser has  been  properly  cleaned.  A  set  oi  read- 
ings, shown  in  Table  I,  were  obtained  from  the  same 
condenser  while  in  actual  operation.     In  order  to  com- 


pare the  performance  obtained,  with  that  expected, 
take  the  case  for  September  14th.  With  a  circulating 
water  temperature  of  "t,  degrees  the  vacuum  expected 
with  a  clean  condenser  is  28.05  inches,  while  that  ac- 
tually obtained  is  only  27.89  inches,  showing  a  vacuum 
discrepancy  of  0.19  inches,  due  to  dirt  and  foreign 
matter  coating  the  tubes. 

The  discrepancy  between  the  vacuum  obtained  and 
that  expected  from  a  clean  condenser  is  given  in  Fig. 
3.  It  should  be  noted  that  the  pressure  difference  be- 
tween that  obtained  and  that  expected  coincide  from 
the  19th  to  the  22nd  day  of  September.  The  way  the 
curve  falls  off  between  the  22nd  and  25th  shows  how 
rapidly  the  condenser  fouls  up. 

It  is  the  writer's  opinion  that  the  average  con- 
densei*  is  not  cleaned  as  often  as  it  should  be,  nor  is 
the  cleaning  as  thorough  as  it  might  be.  There  are  a 
few  isolated  cases  where  there  is  probably  some  ex- 
cuse for  this,  but  in  the  majority  of  cases  it  is  based 
on  an  assumption  which  could  not  be  substantiated  by 
close  examination  of  existing  facts.  For  instance, 
a   condenser  serving  a  large  turbogenerator  unit  may 


314 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


not  be  taken  off  the  line  and  thoroughly  cleaned,  due 
to  the  fact  that  the  water  rate  of  this  machine  is  ma- 
terially less  than  that  of  another  unit,  which  would 
have  to  be  placed  in  service,  thus  increasmg  the  over- 
all steam  consumption  of  the  station.  If,  however, 
the  question  of  economy  was  thoroughly  analyzed  tak- 
ing into  consideration  the  permanent  depreciation  of 


TABLE   I 

—PERFORMANCE    OF   CONDENSER  DURING 

MONTH   OF 

ISEFTEUBEB 

2- 

-« 

£ 

S&: 

&3 

W  i.s 

yi 

5> 

II 

i-g 

> 

1 

24  500 

27.39 

76 

109 

27.49 

2 

24  500 

27.26 

75 

111 

27.34 

3 

24  500 

27.16 

76 

113 

27.18 

4 

24  500 

27.13 

75 

112 

27.26 

5 

20  000 

28.00 

72 

101 

2a>i)2 

6 

22  000 

27.79 

75 

104 

27,83 

7 

24  000 

27.78 

74 

104 

21.83 

8 

24  000 

27.52 

73 

108 

27.56 

9 

24  000 

27.43 

75 

109 

27.49 

10 

24  000 

27.42 

75 

109 

27.49 

11 

24  000 

27.25 

74 

112 

27.26 

12 

21  500 

28.08 

74 

99 

28.13 

13 

24  000 

27.96 

74 

101 

28.02 

14 

24  000 

27.88 

73 

103 

27.89 

15 

24  500 

28.05 

73 

100 

28.07 

16 

24  000 

27.98 

72 

101 

28.02 

17 

24  000 

28.09 

71 

99 

28.13 

18 

24  000 

28.06 

73 

100 

28.07 

19 

17  000 

28.41 

1             69 

1             94 

1          28.40 

20 

24  000 

28.25 

67 

96 

28.29 

21 

24  000 

28.19 

69 

1            97 

28.24 

22 

24  000 

28.13 

71 

1            98 

28.19 

23 

24  000 

28.05 

71 

99 

28.13 

24 

24  500 

27.99 

71 

1          100 

28.07 

25 

24  000 

27.72 

71 

104 

27.88 

26 

23  000 

28.17 

71 

98 

28.19 

27 

20  000 

28.10 

72 

98 

28.19 

28 

20  000 

27.96 

77 

101 

28.02 

29 

20  000 

28.10 

72 

99 

28.13 

30 

18  000 

28.15 

73 

98 

28.19 

1 

the  condenser  tubes,  due  to  the  baking  process,  which 
permanently  decreases  the  B.t.u.  heat  transfer  of  the 
tubes,  it  would  not  be  difficult  for  the  operating  engineer 
to  realize  the  advantages  of  giving  the  condensers  a 
frequent  and  thorough  cleaning. 

TYPES   AND    METHODS    OF    CLEANING 

I — Rodding  of  condenser. 

2 — ^V\'ire  brushes. 

3 — Application  of  cinders  to  the  intake 


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FIG.    I — LOSS   DUE   TO   A    DISCREPANCY    OF    O.I    INCH    VACUCM    WITH 
A  ST.\ND.\RD  25  000  KW  MACHINE 

Assuming  the  cost  of  coal  at  $6.09  per  gross  ton. 

.\ — .'Application  of  air  or  water  pressure  to  condenser 


heads 


The  first  method  is  probably  the  oldest  and  the 
most  expensive.  It  consists  merely  of  cleaning  the 
tubes  by  using  rods  having  practically  the  same  diame- 
ter as  the  inside  of  the  tubes. 

The  application  of  wire  brushes  is  an  expensive 
method  and  is  only  applicable  in  cases  wnere  the  de- 
posit is  of  a  slimy  nature  and  easily  removed. 


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FIG.    2 — PERFORMANCE   CHART    FOR    SURFACE   CONDENSERS 

Vacuum  to  be  expected  with  clean  condenser. 
The  third  method  consists  of  applying  cinders  to 
the  intake  tunnel,  allowing  them  to  circulate  through 
the  water  pump  to  the  condenser  head,  tlirnce  through 
the  condenser  tubes.  This  method  is  probably  the 
least  expensive,  but  will  only  remove  deposits  of  a  verv 
mild  nature  and  incidentallv  is  a  source  of  trouble  in 


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— r-'f        ^«       Iji       14       ,j6       18       ai       »       J^       * 
1    DajofthsMoilth  -  Septeijiber.  1         111! 

5 — Rubber  plugs. 

6 — Scraper  type  cleaners. 

7 — Reversal  of  flow  of  water. 

8 — Combination  of  air  and  water  pressure. 


FIG.  3 DIFFERENCE  BETWEEN  VACUUM  ACTUALLY  OBTAINED  AND 

VACUUM    TO   BE   EXPECTED    WITH    CLEAN    CONDENSER 

case  the  cinders  contain  carbon,  which  will  attack  any 
foreign  material  that  may  be  in  the  tubes.  . 

In  the  fourth  method,  water  or  air  is  applied  to 
the  condenser  head  through  connections  made  by  a 
universal    joint   to   an  external   source   outside   of   the 


July,  1 92 1 


THE  ELECTRIC  JOURNAL 


315 


water  box.  This  method  is  applicable  only  where 
special  provisions  have  been  made  on  the  manhole 
cover  of  the  condenser  heads.  Although  the  process 
materiall}"  decreases  the  amount  of  debris  that  collects 
at  the  entrance  of  the  tubes,  it  does  not  in  any  way  de- 
crease the  deposit  that  may  occur  on  the  inside  of 
the  tubes.     It  is  obvious  that  the  universal  joint  and 


FIG.  4 — ADJUSTABLE 
RUBBER  PLUG 


FIG.  5 — CLEANER  OF  THE 
SCRAPER  TYPE 


connection  must  be  made  at  each  end  of  the  condenser, 
inasmuch  as  the  cleaning  process  goes  on  at  the  same 
time  that  the  condenser  is  in  service  and  the  pressure 
applied  must  be  in  the  same  direction  as  the  flow  of 
water  through  the  condenser  in  order  to  eliminate  any 
water  hammer  effect. 

The  fifth  method  is  well  adapted  to  clean  the  tubes 
when  the  deposit  is  of  a  slimy  nature.  The  adjusta- 
ble rubber  plugs.  Fig.  4,  are  inserted  into  the  tubes  and 
are  driven  through  by  compressed  air  or  water  pres- 
sure. The  plugs  are  so  designed  that  they  will  fit 
the  tube  snugly.  Then  the  applied  pressure  and  the 
resistence  encountered,  due  to  the  deposit,  causes 
them  to  bulge  out,  thus  forming  a  very  effective  clean- 
ing surface.  The  general  method  of  using  rubber 
plugs  is  to  break  the  drain  line  in  the  rear  of  the  con- 
denser and  install  a  perforated  basket  to  catch  the 
plugs  as  they  reach  the  rear  of  the  condenser.  They 
are  then  taken  to  the  front  and  shot  through,  over  and 
over  again.  It  is  not  necessary'  to  remove  the  conden- 
ser heads  unless  the  gases  in  the  condenser  are  ob- 
noxious, and  even  in  such  a  case  a  small  exhaust 
fan    set  up  over    one  of  the  manholes    in    the  rear  of 


Wr.F.MENT    OF    EQCIPMENT    FOR    CLEANING    CONDENSER 
WHEN  HE.\D  HAS  BEEN  REMOVED 

the  condenser  will  insure  pure  air  for  the  men  work- 
ing in  the  front  heads.  In  order  to  use  the  rubber  plugs 
economically,  it  is  advisable  to  use  a  number  of  plugs, 
equal  to  25  percent  of  the  total  number  of  tubes  in  the 
condenser. 


A  cleaner  of  the  scraper  type,  as  shown  in  Fig.  5 
is  applied  in  a  similar  manner  as  the  adjustable  rubber 
plugs.  This  method  of  cleaning  applies  particularly 
to  cases  where  there  is  a  brittle  or  hard  deposit  on  the 
tubes.  The  sketch  in  Fig.  6  illustrates  the  arrange- 
ment required  for  either  the  adjustable  rubber  plug  or 
the  cleaner  of  the  scraper  type,  in  cases  where  the 
condenser  head  has  been  removed.  The  brackets 
which  support  the  scaffold  plank  are  bolted  to  the 
flange  of  the  condenser  and  may  be  set  at  any  eleva- 
tion. The  seat  and  foot  rest  are  made  in  one  piece 
and  can  be  moved  along  the  plank  to  tlie  most  con- 
venient position.  A  three-fourths  inch  quick  opening 
gate  valve  is  supported  from  the  foot  rest  and  is  con- 
trolled by  the  operator's  foot.  Large  condensers  are 
cleaned  without  taking  the  heads  off,  this  eliminates 
the  seat  and  foot  support,  and  the  three-fourth  inch 
valve  is  then  located  adjacent  to  the  nozzle  and  is  op- 
erated by  hand. 

The  seventh  method  is  to  provide  valves  in  the  in- 
take and  discharge  line  of  the  condenser  in  order  to 
reverse  the  flow  of  the  water.     The  first  cost  of  this  ar- 


KIG.   7 — EJECTOR  FOR  APPLYING  LOW-PRESSURE  WATER  TO  THE  TUBES 
BY  COMPRESSED  AIR 

rangement  is  high  and  it  is  doubtful  whetlijer  the  bene- 
fits derived  are  as  satisfactory  as  those  obtained  by 
other  schemes. 

The  eighth  method  consists  of  applying  low  pres- 
sure water  and  air  at  80  pounds  pressure  ro  the  tubes. 
The  equipment.  Fig.  7,  consists  of  a  three  fourth  inch 
T,  into  which  the  one-fourth  inch  air  nozzle  A  is  in- 
serted, thus  forming  an  ejector.  Nozzle  M  is  flatten- 
ed out,  as  shown  in  the  end  view,  so  as  to  impart  a 
spiral  flow  to  the  water.  The  air  connection  is  made 
to  point  A  and  the  water  connection  is  made  at  W ,  us- 
ing water  at  atmospheric  pressure.  It  recfuires  about 
five  seconds  to  clean  each  tube  properly  with  this 
method. 

A  mild  solution  of  hydrochloric  acid  or  caustic 
soda  is  sometimes  used  for  cleaning  condenser  tubes. 
The  solution  is  injected  into  the  system,  filled  with 
water,  which  is  then  brought  up  to  the  boiling  point. 
In  most  cases  the  use  of  chemicals,  for  cleaning  tubes, 
causes  rapid  deterioration  of  the  tubes. 

The  life  of  the  condenser  tubes  will  be  materially 
increased  in  nearly  all  cases  if  proper  consideration 
and  methods  are  adopted  to  clean  the  condenser;  t\-<-^- 
perly  and  periodically 


Mailiocls  OS  jVlaj^jieiic  TDStljM 


THOMAS  SPOONER 

Research  Laboraton.', 
W'estinghouse  Electric  &  Mfg.  Company 


; 
^ 


AN  approximate  determination  of  the  magnetic 
properties  of  materials  is  relatively  simple. 
However,  there  are  so  many  methods  available 
and  so  many  kinds  of  magnetic  materials,  that  the 
novice  is  often  at  a  loss  to  choose  the  best  and  simplest 
method  of  testing.  It  is  our  purpose  to  give  a  resume 
of  the  principal  method,  to  point  out  the  advantages 
and  limitations  and  to  show  which  are  most  suitable,  as 
determined  by  the  material  to  be  tested,  the  accuracy 
desired  and  the  speed  which  is  necessary.  For  research 
work;  where  accurate  fundamental  data  are  sought 
one  may  be  justified  in  using  laborious  methods  and 
complicated     apparatus.     When      routine     acceptance 


spends  to  the  point  where  the  molecular  magnets  all  be- 
come parallel.  The  magnetizing  forces  are  expressed 
in  various  units  as  shown  by  Table  II. 

Gilberts  per  centimeter  and  gausses  are  identical, 
the  latter  term  having  been  adopted  recently  as  the 
unit  of  magnetizing  force.  The  reason  for  adopting 
the  gauss  as  a  unit  of  magnetizing  force  as  well  as  in- 
duction is  that  in  air  a  magnetizing  force  of  one  gilbert 
per  centimeter  produces  an  induction  of  one  line  per 
square  centimeter,  which  is  equal  to  one  gauss.  Most 
scientific  data  are  expressed  in  one  of  these  terms.  In 
this  country  the  designer  generally  uses  ampere-turns 
per  inch. 


TABLE   I— UNITS   OF   INDUCTION 


Maxwells 
or  LineR 

per 
Sq.  In. 

Kilo-Lines 

per 

Sq.  In. 

Lines 

per 

Sq.  Om. 

Gausses 

Kilo-Lines 

per 

Sq.  Cm. 

Kapp  Lines 

per 

Sq.  In. 

Kapp  Lines 

per 

Sq.  Cm. 

. 

1 

1 

1000 

1000 
6.45 
6.45 
6.45 

6450 

6450 

6450 

6000 
38  700 

0.001 
0.001 
1 
1 

0.00645 
0  00645 
0.00645 
6.45 
6.45 
6.45 
6 
38.7 

0.155 

0.165 

155 

155 

1 

1 

1 

1000 

1000 

1000 

930 

6000 

0.155 

0.155 

155 

155 

1 

1 

1 

1000 

1000 

1000 

930 

6000 

0.000155 

0.000155 

0.155 

0.155 

0.001 

0.001 

0.001 

1 

1 

1 

0.93 

6 

0.000167 

0.000167 

0.167 

0.167 

0.001075 

0.001075 

0.001075 

1.075 

1.075 

1.075 

1 

6.45 

0.0000258 
0.0000258 
0.02584 
0.02584 
0.000167 
0.000167 
0.000167 
0.1667 
■    0.1667 
0.1667 
0.155 

1    Kilomaxwell  per  sq.   in 

1    Kilomaxw«U  per   sq.    cm 

1  Kapp  Line  per  sq.  in 

1    Kapp  Line  per  sq.  cm 

tests  are  to  be  made  on  many  samples  a  day,  accuracy 
may  be  sacrificed  for  speed,  reproducibility  of  results 
being  the  only  essential. 

M.\GNETIC   PROrERTIES 

The  chief  magnetic  properties  of  interest  to  the 
engineer  are  normal  induction,  hysteresis  characteris- 
tics and  eddy  current  losses.  The  normal  induction 
data  (which  are  actually  the  locus  of  the  tips  of  a 
series  of  hysteresis  loops)  may  be  expressed  in  a  varie- 
ty of  ways, -but  usually  they  are  given  as  the  values  of 
the  magnetizing  force  H,  Fig.  i,  for  definite  values  of 
induction. 

Various  units  are  used  for  induction  as  indicated 
in  Table  i.  Most  scientific  data  are  expressed  in 
gausses  or  kilo-gausses.  The  majority  of  the  design- 
ers in  this  country  use  lines  per  square  incn. 

In  scientific  literature,  the  term  intensity  of  mag- 
netization /  also  appears,  where, — 

/=^ 

The  engineer  uses  this  term  very  little.  Occasionally 
the  term  ferric  induction  B^  is  used  which  is  equal  to 
BH  or  4  TT I  and  gives  the  increased  magnetic  induction 
due  to  the  presence  of  magnetic  material.  It  is  obvious 
that  B  increases  indefinitely  with  H,  but  B„  and  /  reach 
.I.  definite  limiting  value  called  saturation,  which  corres- 


It  is  often  convenient  to  express  the  normal  in- 
duction data  in  terms  of  permeability,  either  for  a  given 
induction  or  a  given  magnetizing  force,  where  permea- 
bility,— 

B 

when  B  and  H  are  expressed  in  gausses. 

A  fx.H  curve  is  shown  in  Fig.  i.  The  maximum 
permeability  \x.^  maybe  determined  from  the  B-H  curve 
by  drawing  a  tangent  to  this  curve  passing  through  the 

origin.     At  the  point  of  tangency  /Xm^  -jj- 

TABLE   II— UNITS   OF   MAGNETIZING  FORCE 


*                           Gilbert     1                      lAmp-Turns  |Amp-Turns 
per  Cm.      |    Gausses     1    per  Cm.     1     per  In. 

1    Gil     t>i.r  cm                                111           0  796               2.02 

J  Gauss     .■.::■■::     i          i          0.796      2.02 

i   Amp  turn    per    cm..             1.255              1.255              1                       2.54 
1  Amp-turn    per   in...            0.495   |          0.495             0.394             1 

Normal  induction  data  are  of  interest  to  the  de- 
signer chiefly  as  they  enable  him  to  determine  the  num- 
ber of  turns  and  the  magnetizing  current  necessary  to 
bring  his  iron  circuit  up  to  the  desired  induction. 

For  many  purposes  the  data  obtained  from  the 
hysteresis  loop,  Fig.  2,  are  of  primary  importance. 
The  chief  characteristics  of  the  hysteresis  loop  are  the 
maximum  induction  B^  for  a  given  magnetizing  force 
or  the  maximum  magnetizing  force  H^  for  a  given  in- 


July,   1921 


THE  ELECTRIC  JOURNAL 


317 


duction,  the  retentivity  B^,  the  coercive  force  H^  and 
the  hysteresis  loss  as  determined  from  the  ai'ea  of  the 
loop.  5nu  B^  and  H^  are  of  chief  interest  in  connec- 
tion with  such  materials  as  permanent  magnet  stock  or 
cores  for  solenoids.     The  hysteresis  loss  is  of  interest 


<^ 

. 

I 

/ 

\ 

gormJ 

12*2 

QO      ^j 

/ 

> 

\ 

/ 

/ 

'\ 

\ 

A, 

/ 

1 

N 

!^»„ 

/ 

/ 

<o. 

^ 

5^^^ 

/ 

/ 

' 

/, 

/ 

/ 

H 

FIG.    I — NORMAL    INDUCTION    AND    PERMEABILITY    CURVES 

when  the  material  is  subjected  to  alternating  flux,  as 
for  instance  the  cores  of  transformers,  motors,  gener- 
ators, etc. 

DIRECT-CURRENT  TEST   METHODS 

There  is,  in  general,  no  difficulty  in  measuring  in- 
duction with  considerable  accuracy.  It  is  only  in  a 
few  types  of  magnetic  circuit,  however,  that  the  mag- 
netizing force  can  be  readily  measured  with  any  reas- 
sonable  degree  of  accuracy. 

METHODS  OF  MEASURING  INDUCTION 

The  methods  of  measuring  induction  may  be  di- 
vided into  the  following  classes: — 

I — Magnetometric 

2 — Traction 

3 — Deflecting  Coil 

4 — Rotating  Coil 

5 — Bismuth  Spiral 

6 — Polarized  Light 

7 — Ballistic  or  Flux-meter 

8 — Volt-second  Meter 
I — The  magnetometric  method  is  one  of  the  classical 
methods  used  for  much  of  the  early  magnetic  work.'  If  a  long 
sample  of  magnetic  material  is  magnetized  longitudinally, 
magnetic  poles  are  generated  which  may  be  caused  to  act  on 
a  compass  needle  or  magnetometer.  Knowing  the  constants  of 
the  magnetic  needle,  its  distance  from  the  sample,  and  the 
value  of  the  magnetic  field  normally  acting  on  it,  the  induction 
in  the  sample  may  be  calculated. 

2 — The  traction  method  of  measuring  induction  is  based  on 
the  fact  that  the  magnetic  pull  beween  two  pieces  of  magnetized 
material  is  proportional  to  the  square  of  the  induction. 

3 — The  deflection  of  a  D'Arsonval  meter  movement  is  pro- 
portional to  the  current  flowing  in  its  coil  and  to  the  strength  of 
the  magnetic  field  in  which  it  moves.  If  such  an  element  forms  a 
part  of  a  magnetic  circuit  and  the  current  through  the  moving 
coil  is  kept  constant,  the  deflection  of  the  coil  will  be  propor- 
tional to  the  flux  in  the  magnetic  circuit. 

4—-li  a  coil  with  its  axis  at  right  angles  to  a  magnetic 
field  is  caused  to  rotate  at  a  definite  speed,  a  voltage  will  be 
generated  in  it  which  may  be  read  by  means  of  a  suitable 
voltmeter,  and  this  voltage  will  be  proportional  to  the  flux 
threading  the  rotating  coil. 

5 — U  «  piece  of  bismuth  'iuire  coiled  up  in  a  convenient 
form,  such  as  a  spiral,  is  placed  in  a  magnetic  field,  its  electrical 
resistance  will  change  due  to  the  field,  and  this  change  will  be 
a  function  of  the  intensity  of  the  magnetic  field.  By  the  use  of 
a  suitable  bridge  and  calibration  for  the  bismuth,  magnetic 
field  strengths  may  be  readily  determined. 

6 — //  a  beam  of  polarised  light  be  reflected  from  a  magne- 


tized surface  its  angle  of  polarization  will  be  shifted.  The  angle 
of  shift  is  a  funcjion  of  the  magnetic  intensity  at  the  surface 
of  the  metal  and  may  be  measured  in  the  usual  way  by  means 
of  Nicol  prisms. 

7 — The  ballistic  method  is  perhaps  the  simplest  and  most 
used  method  for  measuring  induction.  If  a  magnetized  sample 
is  surrounded  by  a  coil  of  wire  connected  to  a  ballistic  galvan- 
ometer or  flux-meter*  and  the  flux  in  the  sample  is  caused  to 
change,  or  the  coil  is  suddenly  removed  from  the  sample,  the 
galvanometer  or  flux-meter  will  be  deflected  and  this  deflection 
is  a  measure  of  the  change  of  flux  threading  the  coil. 

8 — If  a  coil  of  wire  surrounds  a  magnetized  circuit  and  the 
magnetic  flux  is  changed,   this  change  of  flux  is  proportional 

to  the  (  cdt  where  e  is  the  voltage  generated  in  the  coil.  If  an  in- 
tegrating voltmeter  or  volt-second  meter  is  connected  to  such  a 
coil,  the  reading  of  this  meter  will  be  proportional  to  the  change 
of  flux.  There  is  no  essential  difference  between  the  use  of  a 
flux-meter  and  a  volt-second  meter,  except  that  the  flux-meter 
can  rotate  only  a  fraction  of  a  revolution  whereas  the  volt- 
second  meter  can  rotate  as  many  revolutions  as  desired. 

METHODS    OF    MEASURING    MAGNETIZING    FORCES 

The  methods  of  measuring  magnetizing  forces  are 
as  follows : — 

a — Long  solenoid, 
b — Solenoid  with  ellipsoid  sample 
c — Concentric  air  coils. 
d — Magnetic  potential  coil. 

e — Completely  closed  ferro-magnetic  circuit  with  mag- 
netizing coil. 
f — Compensation  methods, 
a — If   a  long,   uniformly-wound   solenoid  carries  a  known 
current  the  magnetizing  force  at  its  center  will  be  expressed  as 
follows : — 

Where  H  is  in  gilberts  per  centimeter  or  gausses, 
N  is  the  total  number  of  turns  in  the  coil, 
/  is  in  amperes, 

L  is  the  length  of  the  solenoid  in  centimeters. 
If  this   solenoid  contains  an  iron  sample  whose  length  is 
several  hundred  times  its  diameter  this  formula  will  still  hold. 


^1 

' 

^^ 

^ 

^ 

A, 

ta. 

/ 

y 

/ 

7 

} 

0 

a 

1 

i 

\ 

7 

0 

\ 

H„ 

/ 

) 

/ 

J 

/ 

/ 

^ 

/ 

^ 

X, 

FIG.   2 — HYSTERESIS  LOOP 


b — If  the  sample  in  the  above  mentioned  solenoid  is  shorter, 
the  ends  will  exert  an  appreciable  demagnetizing  effect,  and  the 
effective  magnetizing  force  will  be  less  than  that  calculated  by 
formula  (i).  If  the  sample  is  in  the  form  of  an  ellipsoid  this 


*A  ballistic  galvanometer  differs  from  an  ordinary 
D'Arsonval  galvanometer  only  in  having  a  long  natural  period. 
A  flux-meter  is  a  ballistic  galvanometer  which  has  very  little 
restoring  torque  and  which  is  very  much  overdamped  electro- 
magnetically,  i.  e.,  is  used  in  a  very-  low  resistance  circuit.  For  a 
discussion  of  the  characteristics  of  ballistic  galvanometers  and 
flux-meters  see  Law's  "Electrical  Measurements",  or  Leeds  & 
Northup  Co.  Philadelphia,  Pa.,  catalog  on  moving  coil  galvano- 
meters. 


3i8 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No. 


demagnetizing  effect  may  be  calculated  by  means  of  the  demag- 
netizing factors  given  by  Ewing.'  If  the  sample  is  in  the  form 
of  a  cylindrical  rod,  these  same  factors  maf^  be  used  without 
much  error.  The  ellipsoid  is  the  only  form  of  bar  sample  for 
which  the  demagnetizing  factors  can  be  readily  calculated,  due 
to  the  fact  that  in  such  a  sample  the  lines  of  induction  are 
parallel. 

c — If  a  straight  magnetized  bar  is  surrounded  by  a  pair 
of  concentric  helical  coils  having  an  equal  number  of  turns, 
and  these  coils  are  connected  differentially  to  a  ballistic  gal- 
vanometer, we  have  a  means  of  measuring  approximately  the 
magnetizing  force  H,  by  observing  the  galvanometer  deflection 
when  the  flux  through  the  bar  is  reversed.  Such  a  pair  of  coils 
may  be  calibrated  by  placing  them  in  a  long  solenoid  of  known 
constants  with  axes  parallel,  and  reversing  the  current  in  the 
solenoid.  Or  the  constants  may  be  calculated  from  the  number 
of  turns  and  dimensions. 

d — By  means  described  by  Rogowski  and  Steinhaus',  and 
others,  we  may  measure  the  magnetic  potential  directly  between 
any  two  points.  The  method  consists  in  winding  uniformly  many 
turns  of  fine  wire  on  a  thin  flexible  strip  of  nonconducting 
material,  placing  the  coil  in  a  known,  long  solenoid,  and  noting 
the  ballistic  throw  of  a  galvanometer  connected  to  the  coil  when 
the  solenoid  current  is  reversed.  Knowing  the  constants  of  this 
coil,  or  magnetic  potential  meter,  all  that  is  necessary  is  to  apply 
its  two  ends  to  two  points  on  a  magnetic  circuit,  reverse  or 
reduce  the  flux  in  the  magnetic  circuit  and  note  the  deflection 
of  the  ballistic  galvanometer  connected  to  the  coil.  This  will 
give  a  direct  measure  of  the  change  of  magnetic  potential 
between  the  two  points,  if  no  magnetic  potential  is  generated 
by  the  coils  or  otherwise  between  two  points. 

c — If  we  have  a  completely  closed  ferromagnetic  circuit 
surrounded  by  a  uniform  number  of  turns  of  wire  per  unit 
length  of  magnetic  material,  of  which  the  simplest  case  is  the 
ring,  formula  (l)  may  be  applied  directly  to  calculate  the  mag- 
netizing force  from  the  magnetizing  current,  provided  the 
radial  width  of  the  ring  is  several  times  the  diameter.'  If  an  air- 
gap  occurs  in  the  magnetic  circuit  or  a  change  of  cross-sec- 
tion or  material,  or  if  the  coil  is  concentrated,  the  calculation  of 
the  magnetizing  force  then  becomes  difficult  and  more  or  less 
uncertain. 

/—If  the  reluctance  of  the  joints  and  the  yokes  of  a  mag- 
netic circuit  can  be  compensated  for  by  supplying  just  sufficient 
magnetomotive  force  by  means  of  auxiliary  magnetizing  coils, 
then  formula  (l)  may  be  applied  directly  to  the  main  magneti- 
zing coils  for  determining  H. 

APPLICATIONS 

The  magnetometric  method  of  measuring  induction  Ci) 
must  obviously  make  use  of  methods  a  or  6  (long  solenoid)  for 
measuring  H.  Very  complete  descriptions  of  the  method  may  be 
obtained  from  Ewing  or  almost  any  text  book  of  physics.  The 
method  has  the  following  disadvantages. 

I — It  is  very  suspectible  to  outside  influences  such  as 

trolley  lines,  movable  pieces  of  iron,  etc. 

2 — Difficulty  of  obtaining  the  required  samples  in  the 

form  of  long  thin  uniform  rods  or  of  machining  shorter 

samples  in  the  shape  of  ellipsoides. 

3 — The  complication  that  for  any  but  very  long  samples 

the  true  value  of  //  is  a  function  of  B,  thus  requiring  calcu- 
lations. 

The  magnetometric  method  has  two  advantages;  ist,  it  is 
an  absolute  method  capable  of  giving  correct  results  from  the 
dimensions  and  constants  of  the  apparatus;  and  2nd,  it  is  very 
sensitive. 

The  traction  method  of  measuring  induction  (2)  is  best 
exemplified  in  the  Thompson  permeameter",  and  the  DuBois 
permeameterl  In  the  former,  the  induction  is  measured  by 
noting  the  pull  when  the  sample  is  pulled  away  from  the  yoke. 
In  the  DeBois  permeameter,  the  upper  part  of  the  yoke  is  sep- 
arated from  the  lower  by  two  air-gaps  and  is  supported  by 
knife  edges.  The  unbalanced  magnetic  pull  is  counteracted  by 
sliding  weights.  The  rnagnctizing  force  is  measured  from  the 
current  in  the  magnetizing  coils  which  in  both  cases  surroundthe 
samples.  In  neither  type  of  apparatus  can  H  be  calculated  ac- 
curately and  it  can  be  determined  only  by  calibrating  the  ap- 
paratus with  known  samples,  standardized  by  some  absolute 
method.  The  correction  varies  with  each  type  of  material  and 
in  the  Thompson  instrument  with  the  condition  of  the  contact 
surface,  friction  between  the  sample  and  3'oke,  etc.  These 
fraction  methods  are  not  capable  of  high  accuracy  and  are 
ver>-  little  used  today,  though  they  may  find  some  application 
when  a  large  number  of  samples  of  similar  material  are  to  be 
compared. 

I"       Method  3,  using  a  deflecting  coil  for  measuring  induction 
3  ^^cst   illustrated   by   the   well   known   Koepsel   permeameter. 


which  is  similar  to  a  D'Arsonval  type  of  direct-current  meter 
with  the  difference  that  a  constant  current  is  maintained  in 
the  moving  coil,  the  permanent  magnet  is  replaced  by  massive 
yokes,  and  the  sample  to  be  measured  is  surrounded  by  a  mag- 
netizing coil.  A  very  complete  description  of  the  apparatus  is 
given  by  the  Bureau  of  Standards,'  together  with  a  discussion 
of  the  accuracy.  The  magnetizing  forces  with  suitable  correc- 
tions, method  c,  are  determined  from  the  current  in  the  mag- 
netizing coil  surrounding  the  sample.  This  apparatus  has  the 
advantage  that  B  and  H  may  be  made  direct  reading,  but  the 
disadvantage  that  a  different  correction  to  the  value  of  H  must 
bo  applied  for  each  different  kind  of  magnetic  material  tested. 
For  the  determination  of  the  properties  of  a  large  number  of 
samples  of  similar  material,  however,  it  is  very  convenient  es- 
pecially if  the  material  has  comparatively  low  maximum  per- 
meability. This  type  of  apparatus  has  been  used  very  extensively 
in  the  past. 

Method  4,  using  the  rotating  coil,  is  well  illustrated  by  the 
Esterline  permeameter",  which  is  very  similar  to  the  Koepsel 
except  that  the  D'Arsonval  movement  is  replaced  by  a  direct  cur- 
rent armature  with  the  commutator  driven  by  a  direct-current 
motor  coupled  to  a  magneto.  In  determining  H,  an  attempt  is 
made  to  use  method  /  by  means  of  compensating  coils  on  the 
poles.  When  there  is  no  leakage  from  the  ends  of  the  samples,  as 
determined  by  a  magnetometer  needle  placed  close  to  one  end,  it 
is  assumed  that  the  compensation  is  correct.  This  apparatus 
reads  B,  H  and  the  speed  of  the  rotating  armature  directly  on 
a  single  meter  by  means  of  transfer  switches.  It  is  more  com- 
plicated than  the  Koepsel  apparatus  and  according  to  tests 
carried  on  by  the  Bureau  of  Standards  some  years  ago"  has  no 
greater  accuracy.  Errors  in  H,  unless  corrected  by  using  stand- 
ard samples,  are  fifty  percent  or  more  in  some  cases,  for  ordin- 
ary magnetic  materials. 

The  rotating  coil  method  of  determining  flux  has  been  used 
to  advantage  lately  by  Dellenbaugh'"  to  measure  the  flux  in  the 
air-gap  of  rotating  machines.  This  seems  to  be  a  very  quick 
and  satisfactory  method. 

The  bismuth  spiral  method  S,  is  used  only  occasionally  in 
experimental  work,  and  has  the  disadvantage  that  the  tempera- 
ture compensation  must  be  very  carefully  watched. 

The  polarized  light"  method,  6,  has  very  little  application 
as  a  test  method.  It  is  chiefly  of  scientific  interest  and  can  be 
applied  readily  only  for  high  inductions. 

The  ballistic  method,  7,  of  determining  B  is  by  far  the  most 
common  one  used,  and  lies  at  the  foundation  of  the  three  most 
convenient  and  accurate  methods  of  determining  direct-current 
magnetic  properties  which  we  have  available  at  present,  namely, 
the  ring  test,  the  Fahy  permeameter  and  the  Burrows  permea- 
meter. Due  to  their  very  decided  advantages  these  three  type? 
of  test  will  be  considered  in  considerable  detail,  both  as  to 
operation  and  accuracy.* 

RING  TEST 

The  ring  test  is  well  known  and  has  been  widely 
used  in  the  past.  Its  method  of  operation  is  similar  io 
that  followed  for  the  Burrows  and  Fahy  apparatus  to 
be  described  later.  By  following  the  inodifications 
suggested  most  of  the  limitations  considered  formerly 
to  be  inherent  in  the  ring  test  may  be  eliminated.  The 
ring  test  is  the  simplest  method  available  for  obtaining 
magnetic  data  with  a  high  degree  of  absolute  accuracy. 


*A  few  other  types  of  pcrmcameters  using  the  ballistic 
method  for  measuring  B  may  be  mentioned.  In  the  Hopkinson 
divided  bar  method"  the  sample  consists  of  two  bars  which  are 
butted  together  and  inserted  in  a  massive  frame  or  yoke.  A 
magnetizing  coil  surrounds  each  of  the  sample  bars.  A  small 
exploring  coil,  between  the  magnetizing  coils,  is  placed  over  the 
butt  joint  and  connected  to  a  ballistic  galvanometer.  When  one 
of  the  test  bars  is  pulled  out,  the  exploring  coil  is  jerked  out 
from  the  yokes  by  means  of  a  spring,  and  the  induction  existing 
in  the  sample  is  given  by  the  deflection  of  the  ballistic  galvano- 
meter. H  is  determined  from  the  current  in  the  magnetizing 
coil.  Obviously  H  cannot  be  calculated  accumtcly,  but  may  be 
determined  roughly  by  calibrating  the  apparaf"<:  with  known 
material.  Also  the  effective  value  of  H  is  a  function  of  the 
condition  of  the  air-gapfe.  This  apparatus  is  now  practically 
obsolete. 

Another  well-known  type .  of  ballistic  test  is  the  Ewing 
double-bar  method'".  Ewing  undertook  to  overcome  the  dis- 
advantage of  the  yoke  and  joint  reluctance  by  using  two  bars 
machined  to  fit  closely  in   two  yokes.   He  first  measured  the 


July,  1921 


THE  ELECT 


JOURNAL 


3^9 


Fig.  3  shows  the  diagram  of  connections  for  a 
simple  ring  testing  arrangement,  when  several  saiiipL—^ 
are  to  be  tested  at  once.  The  ring  samples  Tj,  T^  and 
Ts  are  wound  with  primary  and  secondary  windings, 
shown  by  the  heavy  and  light  lines  respectively.  The 
primary  windings  are  connected  in  series  through  the 
reversing  switch  6^1  which  reverses  the  main  magnetiz- 
ing current  from  the  battery  B^  through  the  ammeter 
.-Jj,  rheostats  i?,  and  R3  and  short-circuiting  switch 
S.^.  The  rheostats  R2  and  R^  each  have  two  contact 
arms  which  are  insulated  from  each  other;  R^,  having 
low  resistance,  is  used  for  fine  adjustment,  and  i?^  hav- 
ing high  resistance,  is  used  for  coarse  adjustment  of 
the  magnetizing  current.  The  secondary  coils  of  the 
samples  are  connected  through  a  selector  switch  .94  to 
the  secondary  of  the  mutual  inductance  MI  and  the 
ballistic  galvanometer  G.  The  primary  of  the  mutual 
inductance  is  supplied  from  the  battery  i?,  through  the 
ammeter  A^  and  the  reversing  switch  S„. 

In  order  to  calibrate  the  ballistic  galvanometer,  the 
ammeter  /ij  may  be  set  at  one  ampere,  S„  reversed  and 
/?j  and  7?o  adjusted  until  the  ballistic  galvanometer 
reads  10  centimeters.     Now  if 

N,A=io  MI (2) 


FIG.  3 — DIAGRA.M  OF  CONNECTIONS  FOR  A  SIMPLE  RING  TESTING 
APPARATUS 

where  A',  equals  the  secondary  turns  on  each  sample, 
A  equals  the  cross  section  of  sample  in  square  centi- 
meters, and  MI  equals  the  value  of  the  mutual  induc- 
tance, in  millihenries,  then  when  S-^  is  reversed,  one  cen- 
timeter deflection  of  the  galvanometer  will  correspond 
to  one  kilogauss  of  induction  for  the  normal  induction 
curve.  H  may  be  calculated  for  the  sample  from 
equation   (i),  where  L  is  the  mean  circumference  in 

magnetic  properties  with  the  yokes  in  one  position  and  then 
increased  their  distance  apart  by  some  definite  amount,  say 
double,  and  made  a  new  measurement  of  the  magnetic  proper- 
ties. Obviously  if  the  reluctance  of  the  ioints  was  the  same  in 
both  cases  the  difference  in  magnetizing  force  between  the 
first  case  and  the  second  for  a  given  induction  was  due  to  the 
reluctance  of  the  extra  length  of  the  sample,  and  thus  gave  a 
means  of  correcting  for  the  yoke  reluctance.  This  method  has 
the  disadvantages  that  the  joint  reluctances  and  leakage  condi- 
tions are  never  quite  the  same  for  the  two  positions,  that  two 
carefully  machined  duplicate  uniform  samples  are  required,  and 
two  sets  of  data  must  be  determined. 

.'\nother  ingenious  permeameter  depending  on  ballistic 
methods  is  the  Picout",  which  uses  a  novel  method  of  compen- 
sating for  the  reluctance  of  the  yokes.  This  method  is  fully 
described  and  illustrated  in  the  references.  Burrows'  has  shown 
that  this  apparatus  is  subject  to  errors  at  the  higher  inductions. 
Moreover,  the  operation  is  somewhat  tedious. 

The  volt-second  meter  method"  8,  of  measuring  induction 
has  its  chief  application  in  measuring  the  magnetic  properties  of 
transformer  cores  where  even  slow  changes  of  magnetizing 
force  will  generate  quite  appreciable  voltages.  It  makes  a  ready 
method  of  investigating  the  quality  of  transformer  cores  (the 
only  source  of  current  required  being  a  storage  battery)  when 
it  is  desired  to  eliminate  the  disturbing  effect  of  eddy  currents. 


Centimeters.  If  N^,  the  primary  turns  on  the  sample, 
are  of  such  a  number  that  H  equals  /,  then  H  may  be 
read  directly  from  the  ammeter  reading.  By  using 
suitable  shunts  and  a  millivolt-meter,  H  may  be  made 
direct  reading  for  any  convenient  number  of  primary 
turns. 

In  order  to  obtain  a  magnetization  curve  on  the 
samples,  ammeter  A^,  is  set  for  a  definite  value  of  H, 
switch  S^  is  connected  to  the  secondary  01  sample  T,, 
and  6"i  is  reversed.  The  galvanometer  deflection  in 
centimeters  gives  B  in  kilogausses  for  sample  T^. 
Switch  Si  is  then  turned  to  sample  Tj,  switch  5"i  i? 
again  reversed  and  the  corresponding  galvanometer 
deflection  gives  B  for  sample  T„.  After  obtaining  B 
for  all  of  the  samples  at  a  given  H,  A-^  is  increased  to 
another  value  and  the  process  repeated,  thus  obtaining 
a  magnetization  curve  for  each  sample  with  a  minimum 
amount  of  labor  and  no  calculations  after  obtaining  the 
data.  If  desired  the  galvanometer  need  not  be  cali- 
brated, but  a  null  method  may  be  used  by  reversing 
switches  S^  and  ^2  simultaneously  and  adjusting  A., 
until  there  is  no  residual  deflection  of  the  galvanome- 
ter. By  using  suitable  constants  B  can  be  made  nu- 
merically equal  to  the  current  as  measured  by  An ;  or 
again  instead  of  varying  A^  it  may  be  held  constant 
and  a  variable  mutual  inductance  used  which  is 
changed  until  there  is  a  balance  when  S^  and  S.^  are  re- 
versed simultaneously.     In  this  case, — 

J/   X    '0-' 


B 


.y->  A 


(J) 


where  M  is  the  mutual  inductance  in  millihenries,  A'^,  i-'' 
the  number  of  secondary  turns  on  the  sample,  and  A  is 
the  cross  section  in  square  centimeters.  This  formu- 
la is  correct  for  one  ampere  in  the  primaiy  of  the  mu- 
tual inductance.  For  any  other  current,  of  course,  a 
suitable  constant  must  be  applied.  By  this  means 
very  high  sensitivity  may  be  obtained. 

To  obtain  the  hysteresis  loops,  the  most  accurate 
and  satisfactory  method  is  to  refer  each  point  to  the  tip 
value  of  the  loop.  After  putting  the  sample  into  the 
cyclic  condition  by  repeated  reversals  for  the  desired 
maximum  induction  or  maximum  H  value,  switch  .S"-, 
is  opened,  thus  introducing  resistance  into  the  mag- 
netizing circuit  corresponding  to  the  amount  of  resis- 
tance included  between  the  two  contact  points  of  each 
rheostat  R„  and  ^^3.  The  corresponding  deflection  of 
galvanometer  gives  A/?.  (See  Fig.  2,  point  a.)  B  on 
the  hysteresis  loop  then  equals  B^ — ^B. 

Unless  the  galvanometer  has  been  calibrated  for 
double  the  sensitivit)'  used  for  the  magnetization  curve 
the  reading  must  be  multiplied  by  2  to  give  AB  in  kilo- 
gausses.  After  obtaining  point  a,  it  is  usually  conven- 
ient to  obtain  point  — a  having  a  negative  value  oi  H 
equal  to  the  positive  value  a,  by  returning  to  the  tip  of 
the  loop  followed  by  suitable  reversals,  and  then  throw- 
ing switches  S^  and  -S",  down  simultaneously.  This  re- 
duces H  and  also  reverses  it.  Again, 
B-.=B,„—AB  (algebraically). 

By    moving  the    right  hand    contact  points  of    the 


320 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


rheostats,  as  many  points  on  the  hysteresis  loop  as  de- 
desired  may  be  obtained  by  the  above  proces. 

In  another  article",  the  author  has  described  in 
greater  detail  a  more  elaborate  form  of  this  apparatus. 
The  labor  of  winding  the  samples  is  greatly  reduced 
by  using  small  rings  (often  only  one  inch  in  outside 
diameter),  a  few  turns  of  large  wire  for  the  magneti.',- 
ing  coil  and  a  few  secondary  turns  of  small  wire.  The 
small  sample  and  a  few  secondary  turns  are  made  pos- 
sible by  using  a  very  sensitive  ballistic  galvanometer. 
By  immersing  the  samples  in  oil,  as  high  as  lOO  am- 
peres may  be  used  on  the  primary  for  short  intervals 
without  serious  heating,  thus  making  it  possible  with 
a  single  layer  winding  to  go  to  magnetizing  forces  of 
300  gilberts  per  centimeter.  By  the  use  of  ten  sam- 
ples connected  in  series  it  is  possible  to  obtain  complete 
14  point  magnetization  curves  in  4.5  minutes  per  ring 
and  ten  points  hysteresis  loops  in  six  minutes.  It 
requires  less  than  ten  minutes  to  wind  each  sample. 
For  experimental  work  the  samples  may  often  be  pre- 
pared simply  and  cheaply  by  rolling  the  material  into 
sheets  and  punching  rings  with  a  compound  die.  If 
the  radial  width  of  the  sample  is  small  with  reference 
to  the  diameter,  an  appreciable  error  may  be  intro- 
duced*. If  the  radial  width  is  not  more  than  one- 
eighth  the  diameter,  however,  the  errors  due  to  this  ef- 
fect are  practically  negligible. 

The  ring  method  as  described  above  Has  the  fol- 
lowing advantages: — 

I — High  accuracy. 

2 — High  speed. 

3 — A  considerable  number  of  samples  may  be  obtained 
from  one  small  ingot  and  be  given  various  heat  treatments. 

4 — By  roUing  and  punching  the  material  the  cost  of  prepar- 
ing the  samples  is  very  little. 

The  limitations  are  as  follows: — 

I — Small  samples  must  be  annealed  before  testing  to  re- 
move punching  or  machining  strains. 

2 — If  large  samples  arc  used  the  expense  of  winding  is 
prohibitive  for  commercial  tests. 

3 — Some  materials  like  permanent  magnet  steel  and  Epstein 
strips,  prepared  for  core  loss  tests,  require  for  test  a  permea- 
meter  taking  straight  strips  or  bars. 

FAHY  PERMEAMETERS 

Two  new  permeameters  have  recently  appeared  on 
the  market  devised  by  Mr.  Frank  P.  Fahy  and  known 
respectively  as  the  Fahy  duplex  and  the  simplex  per- 
meameters. These  instruments  use  the  ballistic 
method  7  for  measuring  B,  and  the  magnetic  potential 
method  e  for  measurmg  H.  A  complete  description 
of  the  Duplex  instrument  is  given  by  tlie  Bureau 
of  Standard3^  The  Duplex  instrument  may  be 
used  to  give  a  comparison  between  a  standard  sam- 
ple and  an  unknown  or,  if  desired,  a  single  sample  may 
be  used  and  results  obtained  by  what  is  called  the  ab- 
solute method.  Fig.  4  shows  the  essentials  of  the  du- 
plex apparatus,  together  with  the  internal  connections. 
The  magnetic  yoke  is  in  the  form  of  an  H  with  a 
standard  sample  A  and  the  unknown  ,Y  placed  as  shown 
by  the  dotted  lines.  The  magnetizing  coil  M  sends 
flux    around    the    two    circuits     of    the    permeameter? 


through  the  two  samples  as  indicated  by  the  arrows. 
In  general,  due  to  differences  in  the  samples,  these 
fluxes  will  be  different.  In  order  to  make  the  magnetic 
potential  for  the  two  samples  equal,  the  two  secondary 
coils,  T,  D,D'  and  S,  all  having  the  same  number  of 
turns,  are  connected  in  series  with  a  ballistic  galvan- 
ometer so  that  the  induced  e.m.f.  in  coils  6"  and  D'  are 
in  the  same  direction,  but  opposite  to  that  generated 
in  T  and  D.  The  compensating  coils  C  are  supplied 
from  the  same  battery  as  M,  but  through  separate  re- 
versing switches  and  control  resistances.  If,  now,  the 
currents  in  M  and  in  C  are  reversed  simultaneously 
and  the  compensating  current  adjusted  so  that  there  is 
no  residual  deflection  of  the  galvanometer,  the  leak- 
age fluxes  for  two  magnetic  circuits  of  the  permeame- 
ter  will  be  balanced  and  the  same  magnetizing  force 
will  be  applied  to  the  samples.  Then  by  connecting  T 
and  S  successively  to  the  ballistic  galvanometer,  which 
is  calibrated  in  the  usual  way  with  a  mutual  inductance, 
the  values  of  B  for  the  two  samples  may  be  read. 
From  the  known  B-H  curve  for  the  standard  sample, 
H  is  known  for  the  X    sample. 


T 


<^m~r-r%Q 


trfd      Mag. 


laraffi 


FIG.    4 — ELECTRIC.VL    CONNECTIO.MS    OF    THE    FAHY    DUPLEX    PERMEA- 
METER 

In  order  to  test  a  single  bar  by  the  absolute 
method,  the  sample  is  placed  in  T.  The  procedure  is 
the  same  as  for  the  comparison  test  except  that  the 
magnetizing  force  is  read  by  connecting  the  air  coil  H 
to  the  ballistic  galvanometer.  This  coil  has  a  large 
number  of  turns  and  measures  the  diff^erence  in  magne- 
tic potential  between  the  yokes  or  when  ttie  appara- 
tus is  compensated  gives  the  value  of  H  as  applied  to 
the  sample  X  in  coil  T.  The  principle  of  operation  for 
measuring  H  and  determining  hysteresis  data  is  the 
same  as  that  to  be  described  for  the  simplex  apparatus 
below. 

The  simplex  permeameter  is  arranged  as  shown  in 
Fig.  5.  The  center  of  the  iron  yoke  Y  is  supplied  with 
a  magnetizing  winding  M.  The  sample  is  located  at  X 
as  shown  by  the  dotted  lines  and  is  surrounded  by  a 
test  coil  T.  Two  iron  posts  PP  are  clanrped  against 
the  sample  and  carry  between  them  the  air  coil  H,  con- 
sisting of  several  thousand  turns  of  fine  wire.  When 
coil  T  is  connected  to  a  ballistic  galvanometer  and  the 
current  in  M  is  reversed  the  galvanometer  deflection 
will  give  B,  which  may  be  made  direct  reading  as  for 
the   ring   test   described   above  by    suitable   calibration 


July,   1 92 1 


THE  ELECTRIC  JOURNAL 


321 


FIG.    5 — CONNECTIONS 
OF   THE   FAHY   SIMPLEX 
PERMEAMETER 


with  a  mutual  inductance.  If  the  galvanometer  is 
next  connected  to  coil  H,  the  magnetizing  rorce  may  be 
similarly  determined  from  the  deflection  when  M  is  re- 
versed. The  method  of  obtaining  H  is  the  magnetic 
potential  coil  method  d  described  above. 

For  hysteresis  data  B  is  determined  by  first  meas- 
suring  A5  by  introducing  resistance  into  the  "magnetic 
circuit  and  subtracting  A  B  from 
Bm.      (See    description    of    ring 
test.)      II  may    be    determined 
similarly  by  first  measuring  A// 
and  subtracting  it  from  //n.,  or 
if    the    instructions   issued    with 
the  apparatus  are  followed   //  is 
measured  by  reducing  the  induc- 
tion to  the  desired  value  and  de- 
termining //  directly   from    the 
galvanometer  throw   when    con- 
nected to  the  II  coil  by  decreas- 
ing the   magnetizing  current    to 
zero.     This  procedure  will  be  in 
error  if  the  yokes  have  any  ap- 
preciable residual  induction. 
The  simplex  apparatus  is  simple  and  easy  to  use 
and  is  especially  suitable  for  permanent  magnet  steel 
testing.     The  duplex  is  ver\'  nearly  as  complicated  as 
the  Burrows  apparatus  and  probably  is  slightly  less  re- 
liable.    When  comparisons  are  required,  however,  be- 
tween a    standard    and    unknown  samples,  the    duplex 
apparatus  should  have  quite  a  field  of  usefulness. 

BURROWS    PERMEAMETER 

The  Burrows  permeameter^",  within  its  field,  is 
considered  the  most  accurate  instrument  available  for 
magnetic  testing.  B  is  measured  by  the  ballistic  method 
7  and  H  is  determined  by  a  compensating  method  /. 
The  essential  magnetic  and  electrical  circuits  are  shown 
by  Fig.  6.  For  this  test  two  bars  or  sheet  samples  M, 
and  M2  are  required  which  are  placed  in  the  yokes  YY 
as  indicated,  Afi  being  the  sample  under  test.  The  pri- 
mary windings  are  shown  above  the  samples  and  the 
secondary  below.  The  magnetizing  winding  T  for  the 
sample  M^  extends  the  whole  distance  between  the 
yokes.  On  top  of  this,  at  the  ends,  are  placed  the  com- 
pensating windings  /^/j.  Similarly  windings  A  and 
JJ^  surround  sample  M„.  Underneath  the  primary 
windings  close  to  the  samples  are  the  secondary  wind- 
ings as  shown  by  the  fine  lines,  t  is  placed  at  the  cen- 
ter of  sample  Mj  and  a  at  the  center  of  M^.  /^and  y, 
are  placed  about  half  way  between  the  centers  and 
ends  of  the  sample  and  each  has  one  half  the  number 
of  turns  of  t  and  a.  The  function  of  the  compensating 
coils  /,/j  is  to  supply  enough  magnetomotive- force 
to  take  care  of  the  reluctance  of  the  joints  and  yokes. 
That  this  condition  is  satisfied  is  determined  by  means 
of  coils  /j/i  which  must  be  threaded  by  the  same  flux 
as  t,  namely,  there  must  be  no  leakage. 

The  procedure  is  as  follows.  Battery  B^  supplies 
current  to  the  magnetizing  coils  T  and  A  through  the 


reversing  switches  5"i  and  S„  which  are  operated 
together.  Compensating  coils  /^  and  /j  are  supplied 
by  battery  B^  through  switch  S^.  If  now  S^  and  S.^ 
are  reversed  simultaneously,  there  will  be  produced 
in  general  a  deflection  of  the  galvanometer  G  if  switch 
S^  is  set  so  that  a  and  t  are  connected  opposing  (posi- 
tion 2).  This  means  that  the  fluxes  in  M.^  and  M„  are 
not  identical.  By  adjusting  R^  or  R^  these  fluxes  may 
be  made  the  same.  Now  connect  t  and  j■^j■^  in  series 
opposing  by  means  of  switch  S-^,  (position  i)  and  re- 
verse 5"i  and  S2  simultaneously.  If  the  flux  in  M^  is 
not  uniform  there  will  be  a  deflection  of  the  galvano- 
meter. By  adjusting  R^  this  may  be  reduced  to  a  re- 
sidual deflection  x>i  0.  In  general,  it  will  be  necessary 
to  readjust  for  equality  of  t  and  a.  Having  made  this 
adjustment  the  procedure  is  exactly  similar  to  that  fol- 
lowed for  the  ring  test.  By  throwing  5*5  to  the  mutual 
induction  position  3,  the  galvanometer  may  be  cali- 
brated to  read  B  directly  or  a  null  method  may  be  used 
by  varying  the  mutual  inductance  primary  current  or 
the  mutual  inductance  itself  and  reversing  S^  simultan- 
eously with  i"j,  S^  and  S^.  In  order  to  obtain  the  hyster- 
esis loops,  resistances  (not  shown)  are  introduced  into 
the  magnetizing  and  compe^isating  circuits  by  suitable 
switches  and  the  usual  compensations  made.  By  the 
Use  of  a  suitable  gang  switch  these  operations  may  be 
made  quite  simple.  H  is  calclated  from  the  constants 
of  the  primary  coil  T  by  formula  (i),  and  B  from  the 
turns  of  t  and  formula  (2). 

The  operation  may  be  considerably  simplified  if  two 
samples  sufficiently  alike  are  available  so  that  they  may 
be  tested  for  the  mean  value  of  the  two.  In  this  case 
two  more  secondary  compensating  coils  /,/,  similar  to 
j\]\  are  placed  over  sample  M„  and  connected  perma- 


T 


1  Sa  [S, 


FIG.    6 — MAGNETIC   AND   ELECTRICAL    LIRCLTITS    OF   THE   BURROWS 
PERMEAMETER 

nently  in  series  with  j\j\ ;  also  A  and  T  are  connected 
jiermanently  in  series  and  also  a  and  t.  Tests  for 
equality  between  M,^  and  M,  may  now, be  omitted.  This 
procedure  corresponds  to  that  recommended  by  the 
American  Society  for  Testing  Materials^".  This  will 
be  called  the  A.  S.  T.  M.  test  and  the  former  the  pre- 
cision test. 


322 


THE  ELECTRIC  JOURNAL 


\o\.  XVIII,  No.  7 


Fig.  7  shows  the  primary  connections  of  the  Bur- 
rows testing  table  as  used  by  the  Westinghouse  Re- 
search Laboratorj'  and  Fig.  8  the  secondary  connec- 
tions. The  apparatus  is  arranged  for  null  or  deflec- 
tion methods  of  test  by  the  precision  or  A.  S.  T.  A1. 
method    and    for   testing   ring   samples.     The   primary 


KIO.  7— PRIM.-VRY  CONNECTIONS  OF  THE  BURROWS  TESTING  TABLE 


switches  are  operated  by  means  of  foot  levers,  leaving 
the  operator's  hands  free  for  recording  data  and 
changing  the  secondary  switches.  The  primary  am- 
meters and  shunts  are  so  arranged  that  H  is  read  di- 
rectly. Two  types  of  yokes  are  used,  one  for  round 
samples  and  the  other  for  rectangular  bars  or  sheet 
material    of    standard  Epstein  size,  3    cm.    wide.     The 


familiar  with  flie  Ev.:rf  ws  test  can  easily  trace  them 
out. 

The  operation  of  the  Burrows  apparatus,  especial- 
ly for  the  precision  method,  is  rather  complicated  and 
tedious,  but  due  to  its  accuracy  for  commercial  ma- 
terials   these    disadvantages    may    often    be    ignored. 


FIG.   8— SECONDARY   CONNECTIONS   OF   THE   BURROWS   TESTING    TABLE 


flux  enters  the  edge  of  the  sheet  or  bar  samples.  The 
magnetic  circuit  is  shown  by  Fig.  9  for  these  yoke's 
The  method  of  introducing  resistance  for  the  hystere- 
sis loops  is  similar  to  that  used  for  the  ring  test 
described  above,  namely,  using  two  taps  on  a  rheostat 
and  opening  a  short  circuit  between.  No  detailed 
description    of    the  circuits    will  be  given    as  a    person 


FIG.  9 — .\I.\GNETIC  CIRCUIT  OF  BURROWS   PERMEAMETER 

When  the  A.  S.  T.  M.  method  of  test  is  used,  and  there 
is  no  difficulty  in  providing  two  samples  alike,  as  for 
instance  Epstein  strips,  the  operation  is  not  especially 
difficult.  For  routine  tests  for  permeaoility,  at  say 
three  inductions  per  sample,  with  a  suitable  correction 
curve  for  variations  in  the  weight  of  samples,  an  ex- 
perienced operator  can  test  one  hundred  samples  per 
day.  When  reduced  to  its  simplest  forms  for  such 
permeability  tests,  a  non-technical  man  may  be  taught 
in  a  very  short  time  to  operate  the  apparatus  success- 
fully. By  the  use  of  a  variable  mutual  inductance, 
which  may  be  set  to  a  value  correspondmg  to  the  in- 
ductions desired  as  determined  by  the  weight  of  the 
sample  and  using  a  null  method,  no  galvonometer  cali- 
brations are  required. 

REFERENCES 

'"Magnetic  Induction  in  Iron  and  Other  Metals"  by  J.  A. 
liwing. 

'Ewing,  p.  31. 

'Rogowski  &  Steinhaus:  Archiv  fur  Elektroiechnick,  I,  p. 
141  (1912). 

'"Errors  in  Magnetic  Testing  with  Ring  Specimens"'  by  M. 
G.  Lloyd,  Bulletin  Bureau  of  Standards,  Vol.  V,  p.  435,  (1908-9). 

'Ewing,  p.  259;  American  Handbook  for  Elcc.  Engr.,  p.  918; 
Standard  Handbook  for  Elec.  Eng.  p,  188. 

'Ewing,  p.  374;  American  Handbook  for  Elec.  Engr.,  p.  019. 

'"An  E.xpcrimental  Study  of  the  Koepsel  Permcameter"  by 
Chas.  W.  Burrows.  Scientific  Paper.  No.  227,  Bureau  of  Stand- 
ards, .August  1914;  American  Handbook  for  Elec.  Engrs.,  p.  919 
Standard  Handbook  for  Elec.  Engrs.,  p.  188. 

'J.  W.  ^ittrWn^— Transactions  A.  S.  T.  M.  Vol  III,  p.  288, 
(1903);  Vol.  VIII,  p.  190,  (1908).  American  Handbook  for 
Elec.  EngrS.,  p.  924 

'"An  Experimental  Study  of  the  Fahy  Permeamcter"  by 
Chas.  W.  Burrows  and  R.  L.  Sanford.  Bureau  of  Standards. 
Scientific  Paper.  Wo.  306,  p.  286.  August  27,  1917. 

""A  Direct  Recording  Method  of  Measuring  Magnetic  Flu.x 
Distribution"  by  F.  S.  Dellenbaugh  Jr.,  Journal  A.  I.  E.  E.,  p. 
583,  June  1920. 

"Ewing,  p.  158. 

'"Ewing,  p.  362.  .  . 

""Picout  Permeameter"  by  A.  Campbell;  Electrician,  Vol. 
LVIII  p  123,  (1906);  "Electrical  Measurements  and  Practice 
by  Farmer,  p.  330;  Standard  Handbook  for  Electrical  Engine- 

'"'  ""jjie  Eflfcct  of  Displaced  Magnetic  Pulsations  on  the 
Hysteresis  Loss  of  Sheet  Steel"  by  L.  \V  Chubb  and  Thoma, 
Spooncr,  Proceedings  of  A.  I.  E.  E.,  Vol.  XXXIV,  1015. 

""Rapid  Te'iting  of  Magnetic  Materials"  by  Thomas  Spoon- 
er  Electrical  World,  Vol.  LXXIV,  p.  4,  July,  5-  IP'Q-, 

""The  Determination  of  the  Magnetic  Induction  in  Straight 
Bars"  by  C.  W.  Burrows,  Bulletin  Bureau  of  Standards,  Vol. 
VI,  p.  31  (1909).  Also  Bureau  of  Standards  Circular  No.  17. 
Magnetic  Testing  (1916).  . 

"For  standard  methods  of  determining  normal  induction 
and  hysteresis  data,  see  A.  S.  T.  M.  Standards  for  1918,  p.  271. 

"Standard  Handbook  of  Electrical  Engrs.,  p.  186. 
(To  be  continued) 


E.  G.  REED 

Transformer  Engineering  Dcpt., 
Westinghouse  Electric  &  Mfg.  Company 

currentO/ 


VOLTAGE  transformers  are  used  to  step  the 
voltage  of  primary  circuits  down  to  values  suit- 
able for  direct  connection  to  instruments. 
They  are  used  when  the  line  voltage  is  high  enough 
that  connecting  instruments  directly  to  the  circuit 
would  be  dangerous  to  the  operator,  or  would  make  the 
design  of  the  instruments  impracticable.  Essentially 
they  are  constant  voltage  transformers,  designed  for 
close  regulation  and  most  of  the  following  relates  to 
the  question  of  voltage  ratio,  and  to  the  time  phase  re- 
lation of  the  primary  impressed  and  the  secondar}' 
delivered  voltages,  under  various  conditions  of  load. 

VOLTAGE  AND  CURRENT  RELATIONS 

In  Fig.  i,0£p  is  the  voltage  impressed  on  the  pri- 
mary winding  of  the  transformer  and  OE^  is  that  part 
of  the  primary  impressed  voltage  which  balances  the 
counter  e.m.f.  due  to  the  flux  in  the  magnetic  circuit. 
The  difference  in  time  phase  relation  and  magnitude 


at  right  angles  to  OE^  and  in  phase  with 
the  flux  in  the  magnetic  circuit,  is  the  part  which  mag- 
netizes the  iron.  The  part  Oh  is  in  phase  with  OE^ 
and  is  the  current  which  supplies  the  iron  loss  in  the 
magnetic  circuit.  The  impedance  drop  /j-Z'p  in  the 
primary  winding  due  to  the  primary  load  current  is 
made  up  of  two  component ;  the  part  hR^  which  is  in 
phase  with  primary  load  current  0/p  and  the  part  /jXp 
which  is  at  right  angles  to  this  current.  The  imped- 
ance drop  /e^p  through  the  primary  winding  due  to  the 
exciting  current,  is  made  up  of  two  parts  I^R^  which 
is  in  phase  with  OIe  and  /eA'p  which  is  at  right  angles 
to  this  current. 

From  Fig.  i  it  is  apparent  that  the  calculation  of 
the  voltage  ratio  of  a  transformer,  taking  mto  account 
the  drop  in  the  primary  winding  due  to  the  exciting  cm- 
rent,  as  well  as  the  drop  in  both  primary  and  secondary 
windings  due  to  the  load  currents,  is  a  matter  of  some 


ij—.)s 


-VECTOR    RELATIONS    OF    IMPRESSED    .'iND    DELIVERED   VOLTAGES 
AKD  OF  PRI.MARY  AND  SECONDARY  CURRENTS. 

Drawn  for  a  one  to  one  ratio  of  turns 


between  these  two  voltages  is  the  voltage  drop  in  the 
priinary  winding,  due  to  the  primary  current.  In  time 
phase  opposition  to  OE^  is  the  induced  voltage  OE.^  in 
the  secondary  winding.  The  voltage  OE^  is  the  se- 
ondary  terminal  voltage  and  the  difference  between 
0E„  and  OE^  is  due  to  the  voltage  drop  in  the 
secondary  winding  caused  by  the  load  current  01^- 
The  secondary  load  current  O/g  lags  behind  the  sec- 
ondary terminal  voltage  OE^  by  an  angle  6,  whose 
value  depends  on  the  impedance  of  the  load.  The  im- 
pedance drop  in  the  secondary  winding  of  hZ^  is  made 
up  of  two  coinponents,  the  ohmic  element  I^Rs  in  phase 
with  the  current  Oh  and  the  reactive  eletnent  /^A's  at 
right  angles  to  this  current.  The  primary  current 
0/p  is  made  up  of  two  components;  the  part  Oh< 
whose  ampere  turns  balance  the  ampere  turns  in  the 
secondary  winding,  due  to  the  load  current  Oh,  and 
the  exciting  current  0/e.  In  turn  the  exciting  cur- 
rent 0/e  is  made  up  of  two  parts;  Oh,  and  Oh-     The 


T  Flux 

FIG.    2 — VECTORS    REPRESENTING    THE   PRIMARY   VOLTAGES   AND 
CURRENTS  REVERSED 

The  two  impedance  triangles  due  to  the  load  currents  are 
combined  into  one. 


complication.  It  is  also  evident  that  the  voltages  OE, 
and  0£s  are  not  in  exact  opposition  and  that  the 
calculation  of  the  angle  by  which  they  lack  being  in  oj)- 
position,  or  the  phase  angle  of  the  transformer,  also  is 
a  problem  of  some  difficulty. 

VOLTAGE  RATIO 

The  regulation  of  power  and  distributing  trans- 
formers as  ordinarily  exjiressed  is  the  drup  m  second- 
ary voltage  from  no  load  to  full  load  expressed  as  a 
percentage  of  the  full-load  voltage*.  By  definition, 
therefore,  the  regulation  of  such  transformers  is  not 
concerned  with  the  drop  in  the  primary  winding  due 
to  the  exciting  current,  as  this  drop  also  occurs  at  no 

*This  article  should  be  read  as  a  continuation  of  the 
author's  series  on  "The  Essentials  of  Transformer  Practice" 
which  appeared  in  the  Journal  from  July  1917  to  July  1919. 
Expressions  for  calculating  the  regulation  of  power  transfor- 
mers were  developed  in  Part  VI  in  the  Journal  for  Jan.  1918, 
p.  10. 


324 


THE  ELECTRIC  JOURNAL 


Vol.  y.\lU,  No.  7 


load.  For  a  voltage  transformer,  where  the  secondary 
voltage  is  used  for  metering  powder,  it  is  necessary  to 
know  the  ratio  of  the  primary  to  the  secondary  voltage, 
under  the  given  conditions  of  load,  rather  than  the  re- 
gulation. In  determining  this  ratio  it  is  necessary  to 
take  into  account  the  voltage  drop  due  to  the  exciting 
current. 

In  developing  an  expression  for  the  ratio,  it  will 
be  convenient  to  redraw  the  vector  diagram  in  Fig. 
I,  reversing  the  time  phase  relation  of  the  quantities 
for  the  primary  side,  as  shown  in  Fig.  2.  Since  the 
total  impedance  voltage  drop  through  the  transformer 
windings  due  to  the  load  current  cannot  be  separated 
into  the  parts  lost  in  the  primary  and  secondary  coils, 
the  two  impedance  triangles  can  be  combined  into  one, 
as  shown  in  Fig.  2.  Redraw  part  of  Fig.  2  as  shown 
in  Fig.  3,  and  determine  first  the  voltage  ratio  due  to 
the  impedance  drops  in  the  windings  due  to  the  load 
currents.  By  definition,  if  r  is  the  ratio  of  the  primary 
to  the  secondary  turns. 

-'■{'  +  %) 


E„           (E,  +  AF) 
Voltage  ratio  =  -rr-  =  r  ^ 


but  in  Part  \'I  p.  13  it  has  been  shown  that 


AF  =  IR  cos  e  ±  /.V  sin  6  + 


{IX  cos  d  =pfR  sifi  ey- 


FIG.   3— IMPED.\NCE  TRI.'XNGLES  USED  FOR  DERIVING  THE  EXPRESSION 
FOR  THE  VOLTAGE  RATIO 

Therefore, — 

, .  r  _L  A  (/?  cos  e  ±  A'  sin  B)   , 

Voltage  ratio  =  r\i-\-  — ^^ -p + 

i:-  {Xr.osd^Rsin6)-\ 

2E:^  J ^'' 

Where  R  and  X  are  the  equivalent  resistance  and 
reactance  of  the  transformer  winding  referred  to  the 
secondary  side.  If  the  equivalent  resistance  and  reac- 
tance are  expressed  in  terms  of  the  primary  winding, 
equation  (i)  becomes, — 

Voltage  ratio  =  r  I  /+  -!i-i ^ + 

I\{XcosQ^R  sinB)A  ^^^ 

2  r-  Ei-  J 

The  signs  +  and  —  are  used  for  a  lagging  load  cur- 
rent and  the  signs  —  and  +  are  used  when  the  load 
current  is  leading. 

When  taking  into  account  the  exciting  current,  an- 
other impedance  triangle  must  be  considered,  as  shown 
in  Figs.  2  and  3.  As  the  impedance  triangle  due  to 
the  exciting  current  is  fixed  in  magnitude  and  phase 
position,  it  will  add  a  fixed  quantity  to  AF,  which  by 
the  method  used  in  part  VI,  is, — 


Adding  this  to  equation  (l)  gives, — 
Voltage  ratio  =  r  [/-j-  ^'  (^  fo^  ^  ^  X  sin  Q)  ^ 

/;•'  {X cos6  =p  R  sin  Oy-   ,   h.  {RyCosy  +  X^,  sin -y)!        ,  ■. 
2E/  rEa  J 

Since  the  squared  term  of  this  expression  is  usual- 
ly negligible,  for  ordinary  work  it  may  be  neglected 
and  equation  (3)  becomes, — 

Voltage  ratio  (approximately)  =  r\/+  A  jR  cos  8  =■=  X sin  6) 
_l_  /e  (Rp  cos  7  -H  Xp  sin  yU  . 

Where  7  is  the  angle  between  the  secondary  in- 
duced voltage  OE,  and  the  reversed  exciting  current 
O/e-  While  the  equivalent  reactance  can  be  calculated 
from  the  constants  of  the  transformer,  or  determined 
by  test,  it  is  not  possible  to  measure  directly  the  value 
of  Xp.  It  will  be  sufficiently  accurate  for  the  present 
purpose,  to  assume  that, — 

a;      /v'p 


X  -  ^i-  V 


■  w 


r> 

s 

/ 

r 

^ 

\ 

/ 

\ 

s 

I 

/ 

\ 

1 

1-201 

> 

V 

\ 

— 100 

u 

e -^ngle]  Between  &c^ 
al  Voltage  ^nd  Spcond^ry 

nd 

iry 

irren 

> 

V 

■< 

U>8 

0  .^..  ^.. 

Uad 

r    7 

\  ■ 

\ 

1 

(- 


R,.  cosy  +  X^sin  y) 


rE, 


FIG.  4 — VARIATION  OF  RATIO  OF  A  VOLTAGE  TRANSFORMER 

With  angle  of  secondary  load  current  from  secondary 
terminal  voltage,  at  full  load  of  200  volt-amperes.  Constants  of 
the  transformer  are  shown  in  Example  No.  i. 

Example  I : — If  a  200  volt-ampere,  60  cycle  voltage  transfor- 
mer has  the  following  constants  at  50  degrees  C,  what  is  the 
voltage  ratio  with  a  load  of  200  volt  amperes  at  80  percent 
power-factor? 

Voltage  ratio  =2300  to  115     i?i,=38o  ohms 

Iron  Loss  :=20  watts         /?s^o.8s  ohms 

Volt  Amperes 

at  no  load      =jSo  2=1.95  ohms  (referred  to 

secondaPi') 
r  =20  X^o.75  ohm  referred  to 

secondary) 

The   equivalent   resistance   referred  to   the  secondary  wind- 
ing is,  by  equation  (4)  Part  II, — 

^So  ,    , 

R  =  0.8s  + ' — :,  =  o.Sj  +  o.gs  =  ■'■■"'  "^""-^ 

The  reactance  of  the  primary  winding  from  equation  (s), 
is, — 

Xp=- jj-^  =  f5SoA»ts 

/,  =  ^  =  /.^jS  amperes         h:  =  -JJ^  =  o.oj^S  amperes 

a,s  7  =  1^=  0.2J        7  =  7J°  ^9'        sin  jf  29'  =  0.96S 

Then  from  equation  (3), — 

[/./iS  (f.SXo.S+o.y^Xo  f) 
■'+ 775 

/./jS-  (o.7/;Xo.S-/.SXo.6)-      0.034S  (:iSoXo.2'i+i5SXo.g6S)'\ 
+       '  2  X  f/3"  *"  ^o  X  tij  J 

=  20  \i-\-o.o286+o.onoo26^-\-o.oo^/s\  =20X1.03238=20.6^7 
In    example    ( i )  the  terms   0.0286  and  0.0000263 


July,  1921 


THE  ELECTRIC  JOURNAL 


325 


are  due  to  the  drops  through  the  impedance  of  the 
windings  caused  by  the  load  current,  and  it  is  apparent 
that  the  quantity  0.0000263  due  to  the  squared  term  is 
negligible.  The  term  0.00375  is  due  to  the  impedance 
drop  through  the  primary  winding  caused  by  the  ex- 
citing current  and  in  this  case  is  about  one-eighth  of 


5-20  6 

i 

^ 

y 

/« 

y 

2 

^ 

• 

^ 

X 

,y 

X 

X 

-200 

^ 

1        2 

0        6 

Voll 

Amp 

=r=s  ^a,n< 

ary  Load 

"T  1 

FIG.   S — VOLTAGE  RATIO  CURVE 

Secondary  load  having  80  percent  power- factor.  The  trans- 
former characteristics  are  given  in  Examples  I,  3  and  4. 

the  value  of  the  term  due  to  the  load  current  in  both 
windings. 

Example  2: — If  a  200  volt  ampere,  60  cycle  voltage  trans- 
former has  the  follovifing  constants  at  50  degrees  C.  what  is 
its  voltage  ratio  with  a  load  of  200  volt  amperes  at  80  percent 
power-factor? 

Voltage  ratio  ^115000  to  115  i?p=^oooo  ohms 

Iron  Loss  =330  watts  i?8=aD.i  ohms 

Volt  amperes  at  no  load  =700  Z=o.i6i  ohms 

r  =1000  X=o.o79  ohms 

10  000 

R  =  0.1  -\r  -J^^  =  o.t  -I-  0.40  =  0.5  ohms 


.\- 


40  000  X  o.O/'g 


0-5 
20n 
—  =  /  .yjS  amperes 


Then  from  equation  (4), — 
Voltage  ralio  (approximately) 


=  0J20  olnn 
joo 


o.oo6og 


y  =  6/°  10' 
sin  61"  10'  =  n.SSi 


'  + 


/ .7^8  (0.5  X  o  cV  -f-  0.079  X  0.6) 
"5 


o.oo6og  {40000  X  0.472  -|-  6320  X  o.5<S/)"| 
1000  X  //5  J 

=   won  |/  -|-  0.00677  +  0.00/29^1  =  1000  X  /.00S06  =  /00S.06 
In  this  example  the  drop  in  the  windings  due  to 
the  load  current  is  about  five  and  one-half  times  the 
voltage  drop  in  the  primary  winding  due  10  the  excit- 
ing  current. 

Example  3 : — Plot  the  voltage  ratio  curve  of  the  trans- 
former in  Example  i  for  a  full  load  of  200  volt  amperes,  at 
power-factors  of  90  degrees  lagging  to  90  degrees  leading.  This 
curve  is  shown  in  Fig.  4. 

VOLTAGE    RATIO    AT    DIFFERENT    LOADS 

For  practical  use  it  is  customary  to  plot  the  volt- 
age ratio  curve  between  the  ratio  as  ordinates  and  volt 
amperes  secondaiy  load  as  abscissae.  The  reason  for 
this  is  that  one  set  of  measuring  instrumcnrs  will  give 
an  entirely  different  load  than  another  group,  and 
therefore  the  ratio  should  be  known  for  various  loads. 
It  is  evident  that  as  the  secondary  voltage  decreases, 
because  of  the  drop  through  the  transformer  windings, 
the  voltage  ratio  will  increase.  The  ratio  curve  will 
therefore  take  the  form  shown  in  Fig.  5  and  a  differ- 


ent curve  is  required  for  each  power-tactor  of  the 
load.  An  examination  of  equation  {4)  will  also  indi- 
cate that  a  voltage  ratio  curve,  with  changing  volt 
ampere  secondary  load  at  a  given  power-factor,  will  be 
a  straight  line.  The  voltage  drop  in  the  primary  wind- 
ing due  to  the  exciting  current  is  a  constant  both  in 
phase  relation  and  magnitude.  For  a  given  power- 
factor  of  secondary  load  the  drops  in  the  primary  and 
secondary  windings  due  to  the  load  currents  are  fixed 
in  phase  relation  and  their  value  is  directly  proportion- 
al to  the  secondary  load  current.  The  total  drop  in 
voltage  is  therefore  the  vector  sum  of  the  fixed  volt- 
age drop  in  the  primary,  and  the  drops  in  the  two  wind- 
ings whose  values  are  directly  proportional  to  the  load 
current.  Such  conditions  will  evidently  result  in  the 
voltage  ratio  curve  being  a  straight  line. 

Example  4 : — Plot  the  voltage  ratio  curve  for  an  80  percent 
power-factor  load,  of  the  transformer  covered  by  examples  I 
and  3.  The  values  for  this  curve  are  calculated  by  the  use  of 
equation  (4)  and  the  curve  is  shown  in  Fig.  5. 

COMPENSATION    FOR   VOLTAGE   RATIO   ERROR 

The  voltage  ratio  curve  shown  in  Fig.  5  does  not 
give  the  correct  voltage  ratio  at  any  load.  The  reason 
for  the  ratio  being  incorrect  at  zero  load,  is  the  drop 
in  the  primary  winding  due  to  tlie  exciting  current. 
In  practical  work,  in  order  to  avoid  as  far  as  possible 
the  use  of  correction  factors,  the  transformer  may  be 
compensated  to  give  the  correct  ratio  of  a  given  sec- 
ondary load.  Knowing  the  characteristics  of  the  mag- 
netic circuit  and  the  windings,  the  voltage  ratio  may 
be  calculated  for  a  given  secondary  load,  and  turns 
added  to  the  secondary  winding  to  compensate  for  the 
error  in  ratio.  For  loads  other  than  the  one  for  which 
the  transformer  is  compensated,  the  ratio  will  still  be 
incorrect.  For  volt  ampere  loads  less  than  the  one  tor 
which  compensation  is  made  the  ratio  will  be  low,  and 
for  larger  loads  the  ratio  will  be  high,  as  is  shown  in 
Fig.  6. 


y 

^ 

10>- 

^ 

X* 

— 2a2 

^ 

X 

l 

10»-*J 

3 

^ 

r^ 

3 
5 

^ 

/' 

v„, 

-Am, 

.r=s. 

ary  L 

oad 

lool 

,y 

!X 

0      1 

i)0     1 

0     1 

0      1 

f     ' 

10     2 

l>o 

FIG.  6 — VOLTAGE  AND   PERCENT  VOLTAGE  RATIO  CURVE 

Compensated  for  40  volt-ampere  load  at  80  percent  power- 
factor.  The  transformer  characteristics  are  given  in  Examples 
I.  3.  4,  5  and  6. 

Example  5  : — For  the  transformer  whose  voltage  ratio  curve 
is  shown  in  Fig.  5,  draw  the  ratio  curve  when  the  transformer 
is  compensated  for  the  ratio  error  at  one-fifth  normal  rated 
secondary  load  and  at  80  percent  power-factoi. 

At  one-fifth  rated  secondary  load  or  40  volt  amperes,  the 
ratio  of  this  transformer,  from  Fig.  5,  is  approximately  20.19. 
In  order  to  bring  the  ratio  to  20  at  40  volt  ampere  load,  the 

20.19 
secondary  voltage  must  be   raised  to  230X ^^232.185  volts. 


326 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


or  in  other  words  the  secondary  turns  of  the  transformer  must 
be  increased  0.95  percent.  The  voltage  ratio  curve  for  this  con- 
dition is  shown  in  Fig.  6. 

PERCENT  VOLTAGE  KATIO  AT  DIFFERENT  LOADS 

In  order  that  the  voltage  ratio  may  be  used  as  the 
direct  correction  factor  to  apply  to  a  power  reading  ob- 
tained by  the  use  of  a  voltage  transformer,  equation 
(4)  may  be  arranged  to  give  the  percentage  ratio  b)' 
dividing  through  by  the  marked  voltage  ratio  of  the 
transformer. 

Percent  voltage  ratio  {approx.) 

/,  (Rcos  e^XsinO) 


marked  ratio  |_  h, 

/e  {Rp  cos  7  -f  Xp  sin  7) " 
rh. 


Example  6: — Draw  the  percent  voltage  ratio  cur^'e  for  the 
transformer  whose  voltage  ratio  curve  is  shown  in  Fig.  6. 

The  ordinates  for  this  curve  arc  obtained  by  multiplying 
the  ordinates  of  Fig.  6  by  100  and  dividing  by  20.  The  new 
scale  of  ordinates  is  shown  at  the  right  in  Fig.  6.. 


EFFECT  OF  CHANGE  IN  OPERATING  VOLTAGE 

In  investigating  the  effect  of  a  change  in  the  pri- 
mary operating  voltage  on  the  characteristics  of  a 
voltage  transformer,  it  will  be  assumed  that  the  second- 
ary load  is  constant  in  magnitude  and  power-factor. 
The  change  in  percent  voltage  ratio  will,  therefore,  be 
that  due  to  the  increase  in  the  exciting  current,  as  the 
primary  impressed  voltage  grows  larger. 

TABLE  I— EFFECT  OF  INCREASED  PRIMARY 
VOLTAGE 


Inlprt 

ssed    Volt,->,i;e 

Walts  IroTi  Loss 

Volt  Amiiepcsat 

No  L.iad 

2300 

20 

80 

2400 

2I.S 

100 

2500 

23-5 

130 

2600 

26 

170 

2700 

28 

200 

2800 

30.5 

300 

2Q00 

33-5 

420 

3000 

36.S 

600 

Example  8: — Draw  a  curve  between  the  percent  voltage 
ratio  as  abscisscae  and  the  primary  impressed  voltage  as  ordin- 
ates for  the  voltage  transformer  covered  by  examples  1,3,4  ^"d  5 
when  the  secondary  load  is  constant  at  200  volt  amperes  and 
80  percent  power-factor.  Assume  also  that  the  iron  loss  and  volt- 
amperes  at  no  load,  of  the  transformer  are  given  in  Table  I 
for  the  various  impressed  primary  voltages. 

The  percent  voltage  ratio  curve  is  shown  in  Fig.  7  as  plotted 
by  the  use  of  equation  (4). 

The  abscissae  up  to  the  vertical  straight  line  in  Fig. 


FIG.   7 — EFFECT  OF  CHANGE  IN  OPERATING  VOLTAGE  ON  THE  PERCENT 
VOLTAGE  RATIO 

With  constant  secondary  load  of  200  volt-amperes  at  80  per- 
cent power-factor.  The  transformer  is  the  same  as  covered  by 
Examples  I,  3,  4  and  5. 

When  using  the  percentage  ratio  curve  of  the 
transformer  employed  in  making  a  power  measure 
ment,  in  order  to  eliminate  the  error  due  to  its  voltage 
ratio,  the  power  reading  should  be  multiplied  by  the 
percentage  ratio  divided  by  100,  or, 
percent  ratio 
100 


True  pOiver 


X  powei  reading 


(/-) 


Example  7: — If  the  transformer  whose  percent  ratio  curve 
is  shown  in  Fig.  6  is  used  in  making  a  power  measurement,  and 
the  load  on  the  transformer  is  90  volt-amperes  with  an  80  per- 
cent power-factor  load,  what  is  the  true  value  of  the  power 
when  its  apparent  value  is  90  kw  ? 

From  Fig.  6  the  percent  ratio  at  go  volt  amperes  and  80  per- 
cent power-factor  is  100.7.  From  equation  (7), — 


True  power  =  ■ 


X  90  =  go.6  kw 


FIG.  8 — IMPEDANCE  TRIANGLES  USED  FOR  DERIVING  THE    EXPRESSION 
FOR  THE  PHASE  ANGLE 

7  represents  the  constant  voltage  drop  in  the  trans- 
former due  to  the  load  current  and  the  abscissae  be- 
tween this  straight  line  and  the  curve  represent  voltage 
drops  in  the  primarj'  winding  due  to  the  exciting  cur- 
rent. The  value  of  the  component  caused  by  the  ex- 
citing current  for  the  maximum  impressed  voltage  is 
approximately  two-thirds  of  the  constant  value  caused 
by  the  load  currents.  For  the  transformer  covered  by 
Example  2,  the  voltage  drop  resulting  from  the  exciting 
current  is  relatively  large  compared  to  that  resulting 
from  the  load  currents.  Therefore,  for  that  transform- 
the  voltage  ratio  errors  caused  by  the  exciting  current 
at  primarj'  voltages  above  normal,  are  relatively  large 
compared  to  those  for  the  transformer  covered  by  ex- 
ample No.  I. 

PHASE  ANGLE 

The  phase  angle  of  a  voltage  transformer,  as  is 


July,   1 92 1 


THE  ELECTRIC  JOURNAL 


327 


shown  in  Fig.  2,  is  the  angle  between  the  reversed  pri- 
mary impressed  voltage  0£p  and  the  secondary  de- 
livered voltage  OEs-  It  is  customary  to  think  of  the 
phase  angle  as  lagging,  when  the  secondary  delivered 
voltage  lags  behind  the  reversed  primary  impressed 
voltage,  and  leading  when  the  secondary  is  ahead  of 
the  reversed  primary  voltage.     The  phase  angle  is  the 


FIG.  9 — IMPEDANCE  TRIANGLES  DRAWN  TO  SCALE 

For  values  given  in  Example  I,  which  are  comparable  with 
the  values  usually  found  in  practice. 

sum  of  the  angles  a  and  /?  shown  in  Fig.  z  taking  into 
account  that  the  angle  (3  must  be  added  to  or  sub- 
tracted from  a  depending  upon  the  particular  condi- 
tions involved.     Therefore, 

Phase  angle  =  a  -|-  /i  =  </) 
The  first  step  in  deriving  an  expression  for  the 
phase  angle  is  to  determine  the  angle  a.  To  make  the 
development  more  clear,  a  part  of  Fig.  2  may  be  re- 
drawn as  shown  in  Fig.  8.  Since  the  sine  of  a 
small  angle  is  approximately  equal  to  the  angle  ex- 
pressed in  radians, — 

ah 
a  =  -j^  (approximately)   but 

ab  =  ac  ±  be 

=  h  (Xeosd  ±  K  sine) 

therefore, 
_  lAXcosB^Rsind) 


£s 


(S) 


The  plus  sign  is  to  be  used  for  secondary  currents 


r 

^ 

y 

. 

y 

s 

^ 

X 

y 

<-30 

^ 

y' 

y 

A 

—JO 

y 

<^ 

y 

■ 

. 

1 

' 

* 

' 

.|o 
yoit-A 

J. 

0 
sSec 

4o 

ondary 

2^0 

alio     1 

FIG.    10 — PHASE    ANGLE    OF    THE    TRANSFORMER    IN    EXAMPLE    I 

At  various  values  of  the  volt-ampere  secondary  load,  which 
has  a  power-factor  of  80  percent.  In  this  case  the  phase  angle 
:s  leading, 

of  leading  power-factor,  and  the  minus  sign  for  lagging 
power  factor  currents.     Similarly, — 

_  A:  (A',,  COS  7  —  R,,  sin  7) 

A  minus  sign  is  always  to  be  used  between  these 
two  terms,  because  the  conditions  are  similar  to  a  lag- 
ging power-factor  load,  since  the  exciting  current  al- 
ways lags  behind  the  primary  impressed  voltage. 

In  Fig.  8  the  assumption  regarding  the  angle  y  is 


not  quite  correct,  since  the  true  value  of  y,  as  is  shown 
in  Fig.  2,  is  the  angle  between  the  voltage  OE^  and  the 
currentO/s.     The  phase  angle  therefore  is, — 


=  a  +  /3  (radians)  = 


/s  (Xcosd  =^  Rsin  6) 


Iy.  (-Vp  cos  7-  RfSiny) 
rE, 


(9) 

A  consideration  of  equation  (9)  will  indicate 
that  when  the  phase  angle  is  positive  in  sign,  OE^  is 
lagging  in  phase  relation  behind  OE^,  and  when  the 
phase  angle  is  negative  in  sign  that  OE^  leads  in  phase 
relation  the  voltage  0£p.  As  a  matter  of  fact  the 
phase  angle  is  usually  negative  with  lagging  loads. 
In  Figs. I,  2,  3,  and  8  the  impedance  triangles  have  been 
greatly  exaggerated,  as  they  would  not  be  legible  if 
drawn  to  scale  on  a  complete  vector  diagram.  In  Fig. 
9  these  triangles  have  been  separated  from  the  rest  of 
the  vectors  and  drawn  to  scale,  from  the  constants 
given  in  Example  i,  with  a  load  of  200  volt  amperes 
at  an  80  percent  lagging  power-factor.  Fig.  9  shows 
that  the  phase  angle  Q  will  usually  be  negative  with  a 
lagging  load,  on  account  of  the  great  preponderance  of 
resistance    over     reactance    in     the    usual    commercial 


-TlOD 

s. 

> 

V 

— -^-60 
5 

N 

L 

\ 

J-l- 

N 

Ter 

ninal 

Angle 

;e\and  Seionda 

hdary 
-V  Lo 

dCu 

rent 

a 

9 

1°      7 

p.  5 

Lag 

y      _, 

.-A^ 

r       3 

V  -5 

Lead 

Y    9 

f^ 

1  a' 
S 

-|r60 
< 

-  S-80 

-I-IOO 

\ 

\ 

s 

••«• 

■^ 

FIG.    II — VARIATION  OF  THE  PHASE  ANGLE  WITH  THE  ANGLE  OF 
SECONDARY  LOAD  CURRENT  FROM   SECONDARY  TERMINAL  VOLTAGE 

At  full  load  of  200  volt-amperes.  Constants  of  the  trans- 
former are  given  in  Example  I. 

transformer,  although  this  angle  must  be  positive  with 
a  load  of  unity  power-factor. 

Equation  (9)  may  be  written  as  follows  to  express 
the  phase  angle  in  minutes, — 
Phase  angle  {mitt.)  =  j^jS 

["/,  {Xcosd  ±  R  sind)  _^  /k  (.V,,  cos  7  -  >?,,  sin  7) 


{,0) 


E,  .      rE,  1 

Example  9 : — What  is  the  phase  angle  at  50  degrees  C  of  the 
voltage  transformer  whose  characteristics  are  shown  in  Exam- 
ple I,  with  a  load  of  200  volt  amperes  at  an  80  percent  lagging 
power- lacior.' 

l"rom  equir.os  (^0^, — 
Phase  angle  =  j^jS 

[1.73S  {o.rsXo.S-f.SXo.f')       o.o,j/S  {/';S X o .is sSo X 0.06S)  1 
115  ^o  X  J15  J 

=  y4^^  (—  ".<"'7-5  ~  0.00491/)   =  j^jS   (—  0.01224)  =   —  42  inin. 

The  minus  sign  of  the  phase  angle  indicates  that  the  second- 
ary voltage  is  leading  the  reversed  primary  voltage,  as  .shown  in 
Fig.  9.  The  relative  values  of  the  two  terms  0.00725  and  0.00499 
indicate  the  relative  amounts  which  the  voltage  drops  due  to 
the  load  currents  and  the  exciting  current,  respectively  contrib- 
ute to  the  phase  angle  of  the  transformer  under  the  particular 
conditions  of  the  example. 


328 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


Example  lo: — What  is  the  phase  angle  at  50  degrees  C,  of 
the  transformer  whose  characteristics  are  shown  in  example  2, 
with  a  load  of  200  volt  amperes  at  an  80  percent  lagging  power- 
factor  ? 

From  equation  10, — 

\/.73S  {0.079  X  0.8  -  0.5  X  0.6) 
Phase  angle  =  J43S  I — 

0.00609  {6320  X  0.47^  —  40000  X  o.c'i.s'/'j 
''"  1000  X  Its  J 

=  343S  (-  0.00357  -  0.00:71)  =3438  (,-o.oos2S)  =  -  /S./5  min. 
While  Example  9  gives  the  phase  angle  of  the 
transformer  for  a  particular  condition  of  secondary 
load,  this  single  value  would  be  of  very  little  practical 
use.  The  secondary  load  conditions  in  another  appli- 
cation of  the  transformer  might  be  entirely  different, 
both  as  regards  magnitude  and  power-factor.  It  is 
therefore,  customarj'  to  plot  phase  angle  curves  for 
voltage  transformers,  showing  the  phase  angle  for  all 
values  of  the  secondary  volt  ampere  load.  It  is  of 
course  necessary  to  plot  a  different  curve  for  each 
power-factor  of  secondary  load. 


1 

1 

1    "  "1 ' 

AbciS 

Y"~vr 

I 

.^ 

1 

I 

i 

1 

1 

^ 

.'''^ 

raigftt  Line 
UjjCurr 

C^ 

'heCilrve 

X 

I,. 

Inn 

1 

i 

J 

^ 

— 

n 

i    ■ 

1          1     y 

y 

r 

i 

1 

\  Jr 

IPn 

1? 

/ 

:i 

1  % 

/ 

!i,. 

2  1 

/  1 

0 

i  5 

^    i      /• 

. 

1«  in- 

S 

/   1 

i 

li     • 

'^ 

/I 

\ 

1 

i 

' 

1 

:>           5 

1 

ra       1       9|0 
1    Ph4s«  Angle  in 

ilo 

' 

0 

1 

? 

FIG.    12— EFFECT  OF  CHANGE  IN  OPERATING  VOLTAGE  ON  THE  PHASE 
ANGLE 

With  constant  secondary  load  of  200  volt-amperes  at  80  per- 
cent power-factor.  The  transfonner  is  the  same  as  covered  by 
Examples  l  and  9. 

Example  11: — Plot  the  phase  angle  curve  of  the  transfor- 
mer in  Example  i,  up  to  300  volt  ampere  load. 

This  curve  is  shown  in  Fig.  10. 

Example  12: — Plot  the  phase  angle  curve  for  the  trans- 
former in  Example  i,  for  a  full  load  of  200  volt  amperes,  at 
load  power-factors  corresponding  to  90  degrees  lagging  to  90 
degrees  leading. 

This  curve  is  shown  in  Fig.  11. 

EFFECT  OF  CHANGE  IN   OPERATING  VOLTAGE  ON   PHASE 
ANGLE 

In  investigating  the  effect  of  increasing  the  opera- 
ting voltage  on  the  voltage  ratio,  the  secondary  load 
was  maintained  constant  so  that  the  change  in  ratio 
was  due  to  the  increase  in  the  exciting  current  of  the 
transformer  at  their  higher  voltages.  For  this  same 
reason  the  secondary  load  will  be  considered  as  con- 
stant, when  analyzing  the  effect  on  the  phase  angle  of 
increasing  operating  voltage. 

Example  13 : — Draw  a  curve  between  the  phase  angle  as 
abscissae  and  the  primary  impressed  voltage  as  ordinates,  of 
the  voltage  transformer  in  Example  I,  when  the  secondary 
load  is  constant  at  200  volt  amperes  and  80  percent  power- 
factor.  Assume,  also,  that  the  iron  loss  and  volt  amperes  at  no 


load  for  the  various  impressed  voltages  are  the  same  as  those 
given  in  Table  I. 

This  curve  is  shown  in  Fig.  12.  The  abscissae  up  to  the 
vertical  straight  line  represent  the  constant  phase  angle  due  to 
the  load  currents  in  the  primary  and  secondary  windings.  The 
abscissae  between  this  straight  line  and  the  curve  represent 
phase  angles  due  to  the  exciting  current  for  each  value  of  pri- 
mary winding.  The  phase  angle  due  to  the  exciting  current  for 
each  value  of  primary  impressed  voltage  is  constant,  while  the 
angle  due  to  the  load  current  is  dependent  on  the  power-factor 
of  the  secondary  load.  For  a  power-factor  of  secondary  load 
other  than  80  percent,  as  used  in  Fig.  12,  the  relative  values  of 
the  two  factors  contributing  to  the  total  phase  angle  would  be 
entirely  different.  From  a  comparison  of  Figs.  8  and  12,  it  is 
apparent  that  the  exciting  current  is  relatively  a  greater  factor 
in  causing  the  phase  angle  than  it  is  in  contributing  to  the  ratio 
error. 

CORRECTION   FOR  RATIO  AND  PHASE  ANGLE  ERRORS 

As  indicated  in  equation  (7)  the  percent  ratio  di- 
vided by  100  is  the  direct  correction  factor  to  apply  to 
a  power  reading  obtained  by  the  use  of  a  voltage  trans- 
former, to  correct  for  the  ratio  error. 

The  displacement  of  the  secondary  terminal  volt- 
age from  the  reversed  primary  voltage  need  not  be  con- 
sidered when  the  transformer  is  used  with  instruments 
which  depend  on  the  voltage  only.  When  the  trans- 
former   is  used  in   metering  power,  the    effect   of    the 


FIG.    13 — VECTOR    RELATION    BETWEEN    THE    UNE   CURRENT   AND   THE 
REVERSED    PRIMARY    AND    THE    SECONDARY    VOLTAGES 

The  secondary  voltage  is  shown  as  leading  the  reversed 
primary  voltage. 

phase  angle  must  be  taken  into  account,  as  the  power 

reading  will  varj'  slightly  with  the  phase  angle  of  the 

transformer.     From  Fig.  13  it  is  evident, — 

True  power  =  /f,,  cos  6 

Power  reading  =  IE,  X  marked  ratio  X  cos  (d    ±  (j>) 


True  power  =  -gl~  X  ,„^^J^  ,.^/ ■„  X 
true  ratio  co. 


marked  ratio 
percent  ratio 


cos  (d'  ±  (t>) 


(OS  o        ^  p07c'er 
cos  (d'^<t>)  reading 

X  pozver  reading 


X  power  reading 


too  cos  (8'  =fc  0) 

The  plus  sign  is  to  be  used  when  the  phase  angle 
is  leading  and  the  minus  sign  when  it  is  lagging. 

Example  14:— What  is  the  true  power  when  a  power  read- 
ing of  75  lew  is  secured  by  the  use  of  a  voltage  transformer 
whose  percentage  ratio  is  101.35  and  whose  leading  phase  angle 
is  50  minutes,  and  the  power-factor  of  the  line  current  is  80 
percent. 

From  equation  (11), — 

/o/  '^  08 

True  power  =  — — 


,     ^  cos  (s6°sz'  -I-  50')  ^  '^ 

roi.31;        o.S 

^  X =  76.9  kw. 

100         0.7912       '    ^ 

OTHER   FACTORS  EFFECTING  RATIO  AND  PHASE  ANGLE 

All  influences  tending  to  increase  the  iron  loss  and 
exciting  current  of  a  voltage  transformer  will  increase 
both  the  ratio  and  phase  angle  errors.     The  most  im- 


July,  1921 


THE  ELECTRIC  JOURNAL 


329 


portant  of  these  factors,  aside  from  operating  at  volt- 
ages above  normal,  are : — 

I — Iron  ageing. 

2 — Variations  of  wave  of  e.  m.  f. 

3 — Operation  at  reduced  frequency. 

When  non-aging  silicon  steel  is  used  in  the  con- 
struction of  the  voltage  transformer,  the  matter  of  the 
influence    of    the  iron    ageing  on    the  ratio  and    phase 


~^ 

7 

/ 

/ 

/ 

r 

1 

y 

/ 

s 

/ 

/ 

£ 

/ 

'has. 

Ang 

e      Q 

nMu 

lites 

1 

0      1 

0      1 
POi- 

0      g 

)       4 

0        2 

/ 

I  ' 

)        4 

0       6 

N«ga 

te  Angle's 

0      1 

io   i 

0 

Sec 

?ndar 

•  Vol 

age  L 

aggin 

y 

Secor 

dary 

Voltaie  U 

.ading 

/ 

/ 

j- 

y 

/ 

.2 

y 

/ 

/ 

/ 

/ 

/ 

FIG.   14 — EFFECT  ON  THE  POWER  READING  OF  VARIOUS  VALUES  OF  THE 
TRANSFORMER  PHASE  ANGLE 

On  the  assumption  that  the  power-factor  of  the  line  is  80 
per  cent. 

angle  may  be  ignored,  for  the  reason  that  a  small  in- 
crease in  the  iron  loss  and  exciting  current  would 
change  the  ratio  and  phase  angle  a  very  small  amount. 
For  the  same  reason  the  variation  of  the  wave  form 
of  e.m.f.  met  with  in  ordinarv  commercial  work  does 


not  increase  the  iron  loss  and  exciting  current  enough 
to  increase  the  ratio  or  phase  angle  error  seriously. 

However,  operating  a  transformer  at  a  reduced 
frequency  may  considerably  increase  the  iron  loss  and 
exciting  current  and  thus  increase  the  ratio  and  phase 
angle  error.  For  example,  operating  a  60  cycle  trans- 
former on  a  50  cycle  circuit  would  increase  the  induc- 
tion in  the  magnetic  circuit  twenty  percent.  This 
would  cause  a  decided  increase  in  the  ratio  and  phase 
angle  errors,  which  would  be  comparable  to  the  in- 
creased error  caused  by  an  increase  of  20  percent  in 
the  operating  voltage,  as  shown  in  Fig.  12.  Operation 
at  50  cycles,  of  course,  would  be  permissible  if  the 
transformer  characteristics  at  60  cycles  were  sufficient- 
ly good  that  increased  iron  loss  and  exciting  current  at 
50  cycles  would  not  be  objectionable. 

POLARITY 

Fundamentally  the  term  polarity  has  the  same 
significance  when  applied  to  a  distribution  or  power 
transformer.  The  matter  of  polarity  is  important  as 
applied  to  distribution  or  power  transformers,  when 
such  units  are  to  be  paralleled.  A  knowledge  of  the 
polarity  permits  the  placing  the  proper  leads  together 
to  establish  the  proper  parallel  connection.  A  knowl- 
edge of  the  polarity  of  a  voltage  transformer  estab- 
lishes the  phase  of  the  secondary  voltage  as  related  to 
the  phase  of  the  voltage  impressed  on  the  primary 
winding,  and  also  the  relative  instantaneous  direc- 
tion of  the  currents  in  the  primary  and  secondary 
leads.  The  polarity  of  voltage  transformers  is  usual- 
ly indicated  by  marks  on  one  primary  and  on  one  sec- 
ondary lead.  The  marks  are  made  so  that  the  instan- 
taneous direction  of  the  currents  are  the  same  in  the 
two  marked  leads.  For  example,  if  the  current  flows 
toward  the  transformer  in  the  marked  primary  lead, 
it  will  flow  away  from  the  transformer  in  the  marked 
secondarv  lead. 


THE 
ELECTRIC 
JOURNAL 


JULY 

1921 


Installation  of  Switching  Equipment  for  Synchronous 
Converter  Substations 


Preparatory  to  installing  switching  equipment  for  a  syn- 
chronous converter  substation,  a  general  arrangement  for  locat- 
ing the  equipment  should  be  carefully  laid  out  in  accordance 
with  a  diagram,  so  that  each  piece  will  go  into  the  most  suitable 
position,  without  requiring  any  rearrangement;  of  apparatus 
during  or  after  installation.  If  the  substation  is  a  new  building, 
the  design  of  the  building  should  be  made  to  accommodate  the 
synchronous  converters,  transformers  and  switching  equipment 
in  the  best  possible  manner.  If  an  old  building  is  used,  consider- 
able remodeling  may  be  needed  to  obtain  the  best  arrangement. 

When  possible,  the  high-tension  equipment  should  be  segre- 
gated from  the  low-tension  equipment.  The  high-tension  leads 
should  come  in  at  one  end  of  the  building,  pass  through  the  high- 
tension  switching  equipment  into  the  transformers.  The  low- 
tension  wiring  should  be  made   to   the   synchronous  converter 


through  the  starting  panel,  to  the  direct-current  switchboard 
and  thence  to  the  low-tension  feeders,  these  feeders  leaving 
the  building  at  the  opposite  end  from  the  incoming  line.  This 
arrangement  permits  of  the  total  isolation  of  all  high-tension 
equipment,  either  within  a  suitable  room  or  behind  a  separate 
protecting  guide  rail  or  barrier;  and  of  the  shortest  possible 
runs  for  the  cable  and  connections.  Fig.  I  shows  a  substation 
designed  as  outlined  above. 

The  high-tension  lightning  arresters  are  usually  mounted 
outdoors,  in  order  to  reduce  the  required  building  space.  The 
low-voltage  lightning  arresters,  on  account  of  their  construc- 
tion, must  necessarily  be  kept  inside.  Where  outdoor  space  is 
at  a  premium,  the  lightning  arresters  can  be  placed  advantage- 
ously on  the  roof  of  the  substation  building,  as  shown  on  Fig.  2. 
The  choke  coils  can  be  located  outdoors  or  indoors  as  desired. 


330 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


\ 


The  high-tension  disconnecting  switches,  oil  circuit  breakers, 
instrument  transformers,  etc.  should  be  mounted  as  close  to 
the  wall  entrance  bushing  as  feasible.  Due  allowances,  of  course, 
must  be  made  for  the  inspection,  repairs  and  removal  of  any 
apparatus  without  disturbing  the  rest  of  the  equipment.  This 
apparatus  should  be  so  grouped  that  all  the  connections  run 
in  as  nearly  a  straight  line  as  possible. 

The  alternating-current  control  board  should  be  located 
in  a  central  and  convenient  position.  The  circuit  breakers  are 
usually  operated  therefrom  by  means  of  remote  mechanical 
or  electrical  control.  The  starting  panels  should  be  located  in 
a  direct  line  between  the  synchronous  converter  and  its  own 
transformer  or  transformer  bank.  This  will  reduce  the  amount 
of  cable  connections  between  transformer  and  converter  to  their 
shortest  possible  length,  and  save  considerable  in  cost  of  installa- 
tion. 

The  panels  controlling  the  direct-current  end  of  the  con- 
verter and  the  direct-current  feeders  should  be  grouped,  and  the 
whole  switchboard  located  in  the  position  central  to  the  total 
number  of  synchronous  converters,  thus  making  the  cable  con- 
nections more  or  less  equal  from  each  machine.  This  location  of 
the  direct-current  switchboard  will  usually  be  such  as  to  give  a 
general  view  of  the  substation,  especially  if  the  station  is  small. 

The  synchronous  converter  starting  panels  should  be  located 
so  that  they  do  not  interfere  with  the  accessibility  of  the  con- 
verter for  inspection,  repairs  and  its  possible  removal. 

The  equalizer  switch  may  be  mounted  on  the  starting  panel. 
This  location  will  shorten  the  equalizer  cables.  In  railway 
substations  the  negative  switch  is  sometimes  mounted  in 
addition  to  the  equalizer  switch,  on  the  starting  panel ;  or  the 

r ' 


formers  must  be  in  place  before  the  concrete  or  brick  work  is 
completed.  It  is  very  important  that  this  work  be  complete  with 
nothing  omitted  when  the  cell  structure  is  finished,  or  consider- 
able time  and  expense  will  be  involved  in  making  additions. 
The  separate  pieces  of  apparatus  should  be  mounted  before 
any  of  the  wiring  is  installed  and  the  connections  in  the  interior 
of  the  substation  made,  including  ground  connections,  before 
the  high-tension  switches  are  connected  to  the  supply  lines. 

Disconnecting  switches  should  be  located  at  a  height  which 
is  beyond  the  possibility  of  accidental  contact,  yet  within  reason- 
able reach  for  operating  purposes.  They  should  also  be  located 
in  such  a  way  that  gravity  will  tend  to  open  rather  than  close 
them.  Care  must  be  observed  that  they  hang  plumb,  and  that  the 
blades  in  the  open  position  will  not  interfere  with  any  of  the 
wiring.  Extreme  care  must  be  observed  to  see  that  switches 
are  properly  lined  up,  that  is  that  the  blades  make  full  and  pro- 
per contact  both  at  the  hinge  jaw  and  at  the  break  jaw,  and 
that  they  enter  the  break  jaw  without  e.xcessive  manipulation.  It 
is  sometimes  necessary  to  grind  in  the  blade,  using  an  applica- 
tion of  vaseline  mixed  with  pumice  stone  or  scouring  powder 
on  blades  at  contact  points.  This  grinding  in  process  can  be 
done  very  easily  and  quickly  by  opening  and  closing  the  switch 
blades  several  times.  This  mixture  must  be  removed  before  the 
switch  is  put  into  actual  operation.  The  connections  to  the  switch 
must  be  on  clean  surfaces.  The  strap  or  terminal  connections 
should  be  parallel  to  the  surface  of  the  connection  block  or 
lamination  before  bolting  down.  Care  must  be  observed  to  pre- 
vent external  connections  to  the  switch  applying  any  great 
amount  of  strain  upon  the  switch  itself.  To  prevent  this,  heavy 
cable  and  other  connections  to  the  switch  should  be  well  sup- 
ported. 


two  switches  may  be  mounted  on  an  equalizer  pedestal,  which  is 
located  near  the  converter. 

The  switching  equipment  and  switchboard  panels  should 
be  mounted,  if  possible,  so  that  very  little  of  the  machine  vibra- 
tion will  be  transmitted  to  them.  This  applies  particularly  to  the 
switchboard  panels  on  which  instruments  and  carbon  circuit 
breakers  are  mounted.  These  instruments  must  be  as  free  as 
possible  from  any  vibration  if  accuracy  and  good  operation 
conditions  are  to  be  maintained. 

The  actual  time  required  for  the  construction  work  and 
erection  of  the  equipment  can  be  considerably  reduced  if  all 
mounting  details  are  located  before  the  arrival  of  apparatus. 
The  mounting  bolts  for  current  transformers,  disconnecting 
switches,  pipe  mounting  brackets,  etc.  should  be  in  the  wall  and 
well  set  before  the  apparatus  is  put  thereon.  The  setting  of  these 
bolts  requires  time.  The  channel  iron  base  or  other  means  for 
supporting  the  panels,  should  be  put  in  place  so  that  the  switch- 
board may  be  erected  directly  upon  its  arrival.  The  board  should 
be  well  supported  from  the  rear  by  wall  or  floor  braces  or  by 
some  other  means  that  is  deemed  safe  and  practical.  The  com- 
plete bracing  should  be  done  at  the  time  the  board  is  erected  to 
prevent  any  accident  to  the  board  due  in  inferior  and  temporarj^ 
bracing. 

Where  circuit  breakers,  disconnecting  switches,  etc.  are 
mounted  on  pipe  framework,  this  framework  should  be  assem- 
bled and  erected  complete  before  any  of  the  apparatus  is 
mounted.  The  same  applies  to  masonry  cell  structure  if  used 
instead  of  pipe  structure  for  the  equipment.  Care  should  be 
exercised  in  erecting  cell  structure.  Provision  must  be  made  for 
all  necessary  openings.  The  conduits  for  instruments  and  con- 
trol wiring  must  all  be  be  put  in  and  the  mounting  bolts  for 
bus-bar  supports,  disconnecting  switches  and  instrument  trans- 


Oil  circuit  breakers  that  are  mounted  on  masonry  walls 
must  be  attached  with  bolts  well  imbedded  in  the  wall.  Where 
thin  walls  arc  used,  such  as  four  inch  structures,  it  is  desir- 
able to  run  the  mounting  bolts  through  the  wall  and  add  plate 
washers  under  the  bolt  heads.  Pipe  frame  breakers  must  be  so 
supported  that  no  undue  strain  comes  upon  any  individual  sec- 
tion of  the  pipe.  The  whole  supporting  structure  must  be  very 
rigid  and  able  to  withstand  the  opening  and  closing  of  the 
breakers  without  undue  vibration.  Extra  heavy  breakers  require 
rear  pipe  supports.  These  supports  must  be  so  adjusted  that  they 
take  their  proper  share  of  the  total  load.  The  breakers  must  be 
installed  in  a  position  that  permits  accessibility  for  inspection 
and  repair  of  contacts  and  removal  of  oil  tanks.  This  location 
must  also  be  such  as  to  present  no  danger  to  the  attendants  or 
interference  with  the  adjacent  apparatus  when  their  repair  or 
inspection  is  being  made.  The  operating  mechanisms  must  be 
carefully  checked  and  adjusted.  Remote  control  hand  operated 
breakers  should  be  so  arranged  that  the  operating  pipes  are  in 
tension  when  closing  the  breaker.  The  force  for  closing  the 
breaker  must  not  be  so  great  as  to  tend  to  pull  the  bell  cranks 
from  their  foundations.  This  is  liable  to  happen  unless  careful 
adjustment  of  the  travel  has  been  made  by  means  of  the  set 
screw  on  ireaker  frame  and  the  correct  proportioning  of  the 
connecting  rods.  If  this  set  screw  is  too  far  out,  it  w^ill  prevent 
the  breaker  from  locking  in.  If  this  occurs  the  operator  will 
attempt  to  force  the  breaker  closed  thus  pulling  up  the  hell 
crank  bearings.  Precaution  must  also  be  taken  against  the  set 
screw  not  being  out  far  enough,  otherwise  the  travel  will  be  too 
far  and  injure  the  breaker  contacts.  The  bell  cranks  with  their 
operating  rods  should  be  mounted  below  the  floor  or  in  trenches. 
These  trenches  should  be  of  sufficient  depth  that  the  bell  cranks 
will  not  project  above  the  floor  level  and  be  a  menace  to  the  sta- 


July,  1 92 1 


THE  ELECTRIC  JOURNAL 


331 


tion  attendants.  The  operating  coil  voltages  of  electrically  operat- 
ed breakers  require  checking  against  the  available  operating  volt- 
age of  the  station.  The  dash  pots  and  accelerating  devices  for 
hand  operated  breakers  must  be  carefully  checked  to  see  that 
there  is  no  interference  to  good  operation.  The  adjustment  of  the 
main  brush  contacts  and  arcing  tips  must  be  checked.  It  is  very 
important  that  the  brushes  make  good  contact  to  reduce  heating 
and  trouble  from  arcing.  This  check  can  very  easily  be  made  by 
moving  the  breaker  contacts  slowing  in  and  out  and  noting 
whether  the  moving  contacts  press  well  against  the  stationary 
contacts.  A  shiny  surface  indicates  good  contact,  but  the  check 
for  pressure  of  contact  can  also  be  made  by  feeling  the  contact 
when  the  breaker  is  closing  and  noting  the  force  required  to 
close  it.  These  adjustments  are  all  made  at  the  factory  and  if 
the  breaker  is  not  disturbed  during_  shipping,  unpacking  and 
setting  up,  a  mere  check  is  all  that  is  necessary,  with  perhaps 
a  few  minor  adjustments.  Dirt  and  foreign  substances  such  as 
excess  paint,  rust,  etc.  must  be  removed  from  moving  contact 
surfaces  of  pins,  bell  cranks,  etc.,  and  oil  applied.  After  the 
connections  have  been  made  to  the  breaker,  the  terminals  should 
be  insulated  with  tape  or  micarta  housings  of  some  kind. 

Current  transformers,  potential  transformers,  fuses,  etc. 
may  be  mounted  directly  upon  the  wall  or  upon  suitable  sup- 
porting brackets.  Fuses  should  be  accessible  for  replacement. 
The  same  care  must  be  exercised  in  making  connections  to  the 
current  transformers  as  has  been  mentioned  previously  for  the 
disconnecting  switches. 


In  locating  lightning  arresters,  the  horn  gaps  must  he  in 
such  a  position  that  in  arcing  they  will  not  flash  to  ground  or 
to  the  line  wires.  The  arrester  proper  should  be  protected  by 
suitable  screening  or  barriers. 

The  panels  must  be  erected  so  that  they  are  plumb  and 
supported  and  braced  in  such  a  way  as  to  keep  them  rigid. 
Circuit  breakers  and  knife  switches  mounted  on  switchboard 
panels  are  lined  up  before  leaving  the  factory.  It  is  well,  how- 
ever, to  check  this  alignment  before  putting  the  board  in  service 
as  it  may  have  been  disturbed  through  shipment  or  while  erect- 
ing. 

Cable  connections  to  the  knife  switches  and  circuit  breakers 
must  be  supported  so  as  to  take  the  strain  and  prevent  the 
cable  from  pulling  out  of  the  terminals  if  they  should  become 
overheated  and  melt  the  solder.  This  same  precaution  should  be 
exercised  in  installing  ammeter  shunts.  The  resistance  bars  of 
the  shunt  are  soldered  to  the  end  blocks.  Therefore,  if  any 
weight  is  suspended  from  these  shunts  they  are  liable  to  pull 
apart,  especially  if  they  become  heated  and  melt  the  solder. 

The  switchboard  panels  should  be  located  a  sufficient  dis- 
tance from  the  wall  or  other  obstruction  to  permit  of  ready 
access  to  the  rear  for  inspection  or  repairs.  All  connections  to 
copper  bus-bars  or  circuit  breakers  and  knife  switch  studs 
should  be  cleaned  before  connected.  This  will  prevent  imdue 
resistance  drop  and  heating  at  these  connecting  points. 

A.  J.  A.  Peterson 


are  invited  to  use  this  dejiartment 
iiring  authentic  information  on  eiettrical 
mechanical  subjects.  Questions  concerning  general  engineer 
ing  theory  or  practice  and  questions  regarding  apparatus  01 
materials  desired  for  particular  ne?ds  will  be  answered 
Specific  data  regarding  design  or  redesign  of  individual  piece; 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self-addressed  stamped  en 
velope  should  accompany  each  query  All  data  necessary  for 
a  complete  underst„nding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
as  the  necessary  information  is  available;  however,  as  each 
queston  is  answered  by  an  expert  and  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


1988 — Two-PH.'vsE  TO  Three-ph.\se 
transformer  connections  for  two- 
phase  to  three-phase  transformation 
are  shown  in  Figs,  (a)  and  (b).  Will 
you  discuss  these  in  detail  showing 
how  to  calculate  the  tap  points  and 
give  vector  diagrams  and  explain  how 
these  connections  give  a  balanced  two- 
phase  voltage.  Can  the  three-phase 
windings  be  connected  in  star  and 
have  the  neutral  grounded  ?  Would 
the  third  harmonic  be  eliminated  in 
the  star  connected,  three-phase  and 
the  closed  delta  sides. 

J.   R.   B.    (ILUNOIS) 


(C)  (d) 

FIGS.    1988— (a),     (b),     (C)     .AND    (d) 

Fig.  (c)  represents  the  secondary  dia- 
gram for  connections  indicated  by  Fig. 
(a).  The  two-phase  voltages  are  from 
terminals  At  A2  and  Bi  B2.  It  is  obvious 
from  Fig.  (c)  that  the  two  voltages  are 
at  right  angles.  Taps  b  and  /  must  be 
so  located  that  ad  will  equal  bf.  ad  is 
86.6  percent  of  ac  and  since  acd  is  an 
equilateral    triangle,    it    follows    that   ab 


and  af  must  equal  86.6  percent  of  ac, 
which  fixes  the  location  for  the  taps. 
Fig.  (d)  represents  the  secondary  dia- 
gram for  connections  indicated  by  Fig. 
(b).  The  two-phase  voltages  are  from 
Ai  A2  and  Bi  B2.  Taps  b  and  e  must  be 
so  located  as  to  give  a  right  angle  be- 
tween the  two  phases  as  indicated  in 
Fig.  (d).  In  order  that  angle  dfc  be  90 
degrees  angles  fdc  and  fed  must  each  be 
45  degrees.  Angle  adc  is  60  degrees ; 
therefore  adf  is  15  degrees  and  abd  is 
105  degrees. 
From  the  law  of  sines : — 

ab         Sin  15" 

or  ab  =  o.267Xad 


ad        Sm  105" 


Also, 


bd 


Sin  60" 


or  bd  ^  o.gXad 


ad  Sin  105" 
ad  is  the  phase  voltage  and  is  i.il  times 
the  two-phase  voltage.  The  primary  or 
three-phase  side  for  either  connection 
can  be  connected  in  star  with  or  without 
the  neutral  grounded.  In  this  respect  it 
is  the  same  as  a  star-delta  three-phase 
connection  and  therefore  will  not  con- 
tain third  harmonic  voltages.         j.  F.  p. 

19S9—  Equivalent  Spacing  of  Trans- 
mission Lines — (a)  In  his  article  on 
"Electrical  Characteristics  of  Trans- 
mission Circuits",  Aug.  1919,  p.  314, 
Mr.  Nesbit  states  that  the  "equivalent 
spacing"  in  the  case  of  three  unsym- 
metrically  spaced  conductors  is  to  be 
taken  as  the  cube  root  of  the  product 
of  the  spacings.  He  states,  further, 
that  the  line  must  be  considered  trans- 
posed to  make  this  equivalent  spacing 
give  accurate  results.  I  have  always 
understood  that,  if  the  line  is  trans- 
posed, the  equivalent  spacing  should 
be  taken  as  the  average  spacing ; 
whereas,  if  the  line  is  not  transposed, 
the   cube   root  of   the  product   of   the 


spacing  should  be  taken.  Will  you 
please  inform  me  which  is  correct? 
(b)  Two  three-phase  4/0  stranded 
double  braid,  weather  proof  insulated 
feeders  are  strung  on  standard  N.  E. 
L.  A.  si.x-pin  cross-arms,  one  circuit 
being  on  each  side  of  the  pole.  The 
two  circuits  are  tied  together  at  each 
end.  What  scheme  of  pairing  the 
conductors  will  give  the  minimum  in- 
ductance drop,  and  what  would  be  the 
"equivalent  spacing"  in  this  case? 

e.  n.  d.  (cal.) 

(a)  The  statement  that  the  equiva- 
lent spacing  in  the  case  of  three  unsym- 
metrically  spaced  conductors  is  to  be 
taken  as  the  cube  root  of  the  product  of 
the  spacing  is  correct.  The  average  of 
the  spacings  is  only  an  appro.ximation  of 
the  equivalent  spacing  and  is  not  tech- 
nically exact.  The  method  of  equivaleni 
spacing  is  accurate  only  if  the  transmis- 
sion lines  are  symmetrically  transposed. 
If  the  lines  are  not  symmetrically  trans- 
posed, there  will  be  unequal  drop  in  the 
different  wires  due  to  the  difference  in 
mutual  reactance.    ' 

( b)  The  arrangement  of  conductors 
on  a  six-pin  cross-arm  having  one  three- 
phase  circuit  on  each  side  of  the  pole 
will  give  the  lowest  reactance.  In 
general,  to  reduce  the  reactance  of  a  cir- 
cuit to  the  miin'mum,  the  conductors  in 
parallel  should  be  separated  as  far  as 
possible.  This  greatest  mean  separation 
is  accomplished  by  connecting  the  con- 
ductors I  and  4,  2  and  5,  and  3  and  6,  in 
parallel,  numbering  from  one  end  of  the 
cross-arm.  R.  D.  E. 

1990—  Current  Rating  of  Switches — 
Why  is  it  that  switches  are  given  a 
higher  ampere  rating  for  direct  cur- 
rent than  for  alternating  current? 
This  question  has  come  up   in   instal- 


332 


THE  ELECTRIC  JOURNAL 


ling  a  triple-pole  switch  of  the  open 
type.  Its  rating  is  2500  amperes, 
direct-current,  and  2300  amperes  alter- 
nating-current. E.  M.  (N.  Y.) 
Any  solid  conductor  of  electric  cur- 
rent may  be  considered  as  being  made 
up  of  a  number  of  smaller  filaments  or 
conductors,  each  filament  carrying  a 
certain  portion  of  the  total  current.  If 
the  conductor  be  straight  and  of  uni- 
form cross-section,  and  if  the  e.  m.  f. 
impressed  across  the  terminals  of  the 
conductor  does  not  vary  with  time,  each 
filament  will  carry  the  same  amoiint  of 
current.  If,  however,  an  alternating  e. 
m.  f.  be  impressed  across  the  terminals 
of  the  conductor,  the  current  will  not 
divide  uniformly  throughout  the  cross- 
section  of  the  conductor.  This  is  called 
"skin  effect"  and  may  be  conveniently 
explained  by  noting  that  the  inner  fila- 
ments of  the  conductor  are  linked  by 
more  flu.x  than  the  outer  filaments.  As 
a  result,  the  counter  e.  m.  f.  induced  in 
the  inner  filaments  is  greater  than  that 
induced  in  the  outer  filaments,  and  be- 
cause of  the  lower  impedance  more  cur- 
rent flows  through  the  outer  filaments. 
The  effective  resistance  of  the  conductor 
is  thereby  increased,  and  this  explains 
why.  for  conductors  of  the  same  size, 
one  carrying  60  cycle  current  runs  hotter 
than  the  one  carrying  direct-current  of 
the  same  value.  Since  "skin  effect" 
varies  directly  as  the  cross-section  of  a 
conductor,  there  is  usually  no  difference 
in  the  alternating-current  and  direct- 
current  ratings  of  switches  and  circuit 
breakers  below  1200  amperes  carrying 
capacity.  However,  "skin  effect"  also 
varies  directly  as  the  frequency,  and  for 
high  frequencies  the  difference  between 
the  alternating-current  and  direct 
current  ratings  would  extend  to  still 
smaller  capacities.  As  a  rule,  however, 
commercial  applications  do  not  go  above 
60  cycles.  G.  G.  G. 

1991 — Recl.\iming  System — Will  you 
please  furnish  us  with  any  informa- 
tion that  you  may  have  on  the  so- 
called  "Reclaiming  System"  installed 
by  large  factories  for  washing  the  rags 
and  waste  used  for  wiping  off  oil, 
polishing  surfaces  or  other  purposes. 
The  reclaiming  system,  besides  fur- 
nishing the  men  with  clean  absorbent 
rags  and  waste,  also  reclaims  the  oil. 

T.  J.   M.    (OHIO) 

The  reclaiming  system  consists  in 
several  steps  namely;  a  centrifugal 
machine  for  driving  off  the  oil,  a  wash- 
ing machine  for  washing  the  rags  and  a 
drying  oven  subsequently  drying  them. 
There  are  several  makers  of  this  class  of 
apparatus  on  the  market.  In  this  clean- 
ing process,  rags  have  one  advantage 
over  waste  in  that  metal  filings  and  turn- 
ings do  not  adhere  to  them  to  the  same 
extent  as  they  do  to  the  waste.  Neither 
rags  nor  waste  should  be  allowed  to  ac- 
cumulate even  for  a  few  hours,  as  spon- 
taneous combustion  may  occur.  This 
feature  has  led  a  number  of  concerns  to 
do  away  with  the  reclaiming  process 
where  it  otherwise  would  have  been  suc- 
cessful, c.  B.  A. 

1992— Reconnecting  Induction  Motor 
—We  have  a  7.5  hp,  single-phase,  133 
cycle,  8  pole,  104  volt,  short-circuiting 
commutator  motor  which  we  want  to 
operate  on  a  60  cycle  circuit.  At  pres- 
ent, the  poles  are  two  in  series,  four 
in  parallel.     Can  the  stator  winding  be 


reconnected  for  220  volts,  60  cycles 
and  at  what  speed  will  it  run?  What 
would  cause  this  motor  to  start  up  and 
come  up  to  speed,  but  as  soon  as  the 
governor  short-circuits  the  commuta- 
tor,  it  comes  to  a  stand  still. 

N.  J.  w.  (n.  v.) 

We  see  no  reason  why  this  machine 
cannot  be  reconnected  to  operate  on  60 
cycles,  220  volts.  The  machine  being 
connected  in  four  parallels  for  104  volts 
133  cycles  has  a  field  strength  \vhich  can 
be  refered  to  as  its  normal  field.  If  it 
is  reconnected  in  series  it  operates  on 
416  volts,  133  cycles  or  on  188  volts  60 
cycles  with  this  same  normal  field 
strength.  To  operate  on  220  volts  60 
cycles  would  cause  the  motor  to  run 
with  a  magnetic  field  17  percent  stronger 
than  normal.  This  is  not  too  much  in- 
creased field  for  standard  motors,  and 
especially  when  the  frequency  is  re- 
duced. The  horse-power  rating  of  the 
machine  would  be  reduced  in  percent 
even  more  than  the  frequency,  and 
would  not  be  more  than  three  hp,  at 
most.  The  new  synchronous  speed 
would  be  900  r.p.m.  We  assume  that  the 
commutator  is  short-circuited  by  centri- 
fugal action  of  the  governor  weights. 
These  weights  must  be  changed  and  ad- 
justed to  such  value  as  to  make  the 
short-circuiting  device  act  near  3/4  to 
5/6  of  the  new  full-load  speed.  Con- 
cerning the  failure  of  the  motor  to  come 
up  to  speed  when  the  short-circuiting 
device  has  acted,  it  would  appear  that 
the  short-circuiting  device  fails  to  short- 
circuit  the  bars  when  the  brushes  have 
lifted.  The  member  which  short-circuits 
the  bars  may  be  burned  out  or  damaeed. 
H.  s.  s. 

igo3_STATic  Wires  of  Transmission 
Circuits — Bv  referring  to  Fig.  fa") 
we  have  a  three-phase,  no  kv  trans- 
mission line.  A,  B.  and  C  being  the 
line  conductors.  .Y,  and  .Y'are  the 
static  wires.  Some  claim  that  the 
static  wires  neutralize  the  induction 
and  that  it  is  not  necessary  to  trans- 
pose the  transmission  line.  Is  this 
so?  If  so  exniain  how  this  is  brought 
about,  also  what  determines  the  posi- 
tion of  the  static  wire  relative  to  that 
of  the  line  conductors.  Will  the 
static  wires  help  in  keepine  down  the 
induction  on  a  telephone  line  run  on 
the  same  poles  as  the  transmission 
line.  In  the  above  case  the  poles  are 
400  feet  apart,  and  the  static  wires  are 
grounded  every  800  feet. 

R.    H.    N.   L.    (BRITISH   COLUMBIA) 

As  the  transmission  line  consists  of 
three  conductors  equally  spaced  in  a 
horizontal  plane,  and  the  ground  wires 
are  located  symmetrically  with  respect 
to  and  in  a  plane  above  the  transmission 
line,  the  ground  wires  form  a  closed 
circuit  at  the  end  of  the  800  foot  sec- 
tions, at  which  points  they  are  connected 
to  ground.  Under  no-load  conditions, 
there  would  be  a  voltage  induced  elec- 
trostatically in  each  ground  wire.  These 
voltages  would  be  of  different  phase, 
and  consequently  cause  a  current  to 
circulate  in  the  loop  formed  by  the 
ground  wires.  In  general,  the  current 
flowing  in  this  loop  would  be  of  such 
duration  as  to  neutralize  the  electro- 
static effects  of  the  transmission  wires. 
The  effect  on  an  adjacent  telephone 
system  would  be  to  slightly  reduce  the 
induced  voltage.  Under  load  conditions, 
the  effect  of  the  currents  in  the  different 


Vol.  XVIII,  No.  7 


wires  would  be  to  induce  elcctroinag- 
netically  a  voltage  in  the  ground  wire 
loop,  which  would  cause  current  to  flow 
in  such  direction  as  to  reduce  the  volt- 
age   induced    by    the    transmission    line 


FIG.  1993  (a) 

currents.  The  effect  on  adjacent  tele- 
phone lines  would  be  to  reduce  the 
amount  of  induced  voltage  slightly 
while  the  effect  of  the  ground  wire  loop 
would  be  to  reduce  the  value  of  voltage 
induced  in  the  telephone  circuits  slightly, 
this  reduction  would  be  so  small  that  the 
effect  of  the  ground  wire  should  not 
enter  into  the  question  of  whether  the 
transmission  wire  should  be  transposed 
or  not.  R.  D.  E. 

1994 — Locating  Short  Circuits  in  Sta- 
tor Coils — Please  give  data  on  the 
winding  of  an  electromagnet  for  use 
on  a  no  volt  lighting  line  for  locating 
short  circuits  in  stator  windings.  I 
have  made  several  unsuccessful  at- 
tempts using  about  22  or  44  sq.  inches 
of  soft  wrought  iron  and  using  60 
turns  of  No.  4  square  magnet  wire  or 
around  60  to  75  feet  of  wire.  Where 
could  I  get  some  laminated  iron? 

G.   H.  G.    (new  jersey) 

The  electromagnet  used  in  testing  for 
short-circuits    in    stator    coils,    consists 


ling  Coil 


Kics.  1994— (a)  AND  (b) 


essentially  of  built  up  U-shaped  punch- 
ings  with  an  exciting  coil  wound  upon 
them,  as  shown  in  Fig.  (a).  For  testing 
small  stator  coils,  the  magnet  core  hav- 
ing a  cross-section  of  about  six  square 
inches  will  require  approximately  120 
turns  of  No.  10  B.  &  S.  wire  in  the  ex- 
citing coil,  for  60  cycles,  no  volts  or  280 
turns  for  25  cycles,  no  volts.  Care 
should  be  taken  in  clamping  the  punch- 


July,  1921 

ings  together;  bolts  made  of  non-mag- 
netic material  such  as  brass  should  be 
used,  otherwise  flux  will  leak  through 
the  bolts.  The  test  consists  in  placing 
one  pole  face  of  the  magnet  over  one 
side  of  the  coil  group,  and  holding  a 
light  piece  of  steel  over  the  other  side 
of  the  stator  coil.  If  current  flows  in 
the  coil,  due  to  a  short-circuit,  the  piece 
of  steel  will  be  attracted.  It  makes  little 
difference  whether  one  or  more  turns  of 
the  coil  under  test  is  short-circuited. 
These  U-shaped  punchings  can  easily  be 
cut  out  from  the  laminated  iron  of  dis- 
carded transformers.  m.  m.  b. 

ig95_PH0T0ELECTRic  Cell— Please  state 
how  to  construct  what  is  called  a 
photo-electric  cell  which  will  produce 
a  current  of  electricity  in  proportion 
to  the  amount  of  light  illummating  the 
cell,  using  either  solar  or  artificial  il- 
lumination (only  excluding  the  infra- 
red rays  which  produce  heat.)  1  he 
cell  to  be  excited  only  by  the  action  of 
light  rays.  A.  A.  R.  (mo.) 

Electrochemical  photo-electric  cells 
may  be  constructed  in  the  following 
manner:— (I )  A  silver  electrode,  well 
cleaned,  is  made  anode  in  a  solution  of 
sodium  chloride,  NaCl,  or  potassium 
iodide,  Kl,  until  it  is  covered  with  a  thin 
coat  of  silver  chloride  or  silver  iodide, 
respectively.  When  placed  in  a  dilute 
sulphuric  acid  solution,  the  potential  of 
this  electrode  varies  with  the  intensity 
of  light  falling  on  it.  For  the  second 
electrode,  a  similarly  coated  silver  elec- 
trode kept  dark  is  used.  A  lead  electrode 
exposed  may  be  used  in  place  of 
the  silver  electrode  kept  dark,  but  in  this 
case,  the  cell  will  develop  a  compara- 
tively large  e.  m.  f.  when  dark,  and  the 
illumination  will  cause  but  small  changes 
in  the  e.  m.  f.  (2)  A  copper  electrode, 
slightly  oxidized  in  a  Bunsen  flame,  may 
be  used  in  a  one  percent  solution  of  so- 
dium or  potassium  hydroxide,  in  place 
of  the  coated  silver  electrode  with  sul- 
phuric acid  as  explained  above.  A  lead 
electrode,  not  kept  dark,  may  be  used 
with  a  copper  electrode  the  same  as 
■with  the  silver  electrode,  except  that 
they  must  be  used  in  the  sodium  or  pot- 
assium hydroxide  solution.  The  changes 
in  e.  m.  f.,  produced  by  illumination  in 
these  cells,  are  very  small  and  will  be 
masked  by  galvanic  polarization  unless 
the  e.  m.  f.  is  determined  by  a  null 
method.  J.  s. 

iggg — St.'^RTING    A    SYNCHRONOUS    MoTOR 

WITH  FuLT,  Field  Excit.\tion — I 
would  like  to  know  if  a  self-starting 
synchronous  motor  will  start  up  and 
pull  itself  into  step  if  the  field  is  fully 
excited  beforehand.  If  it  does  what 
will  be  its  effect  on  the  system? 

c.  G.  R.  (coLO. ) 
The  normal  method  of  starting  a  syn- 
chronous motor  is  to  short-circuit  the 
field  through  the  field  rheostat  set  in  the 
running  position.  The  field  is  excitated 
only  after  the  motor  has  approached 
within  a  very  small  fraction  of  syn- 
chronous speed.  If  the  excitation  be 
applied  with  the  machine  at  rest  the 
magnetic  circuit  will  be  saturated,  Avhich 
will  reduce  the  torque  and  increase  the 
kv-a.  There  will  be  a  certain  amount  of 
extna  surging  in  the  alternating-current 
line,  and  current  pulsations  in  the  direct- 
current  line,  of  slip  frequency.  After 
the  motor  has  started  there  will  be  a 
counter  torque  developed  due  to  excita- 


THE  ELECTRIC  JOURNAL 

tion  and  under  some  conditions  this 
torque  might  actually  stall  the  motor  at 
a  low  speed.  e.  b.  s. 

1997— Generator  for  Welding  Outfit 
— About  one  year  ago  we  bought  a  15 
kw,  60  volt,  250  ampere,  direct-current 
generator  for  welding  purposes.  Dur- 
ing the  first  six  months  the  machine 
rendered  excellent  service,  but  during 
the  last  six  months  we  have  been  hav- 
ing considerable  trouble  in  keeping  the 
voltage  steady.  The  voltage  jumps  up 
and  down,  between  five  and  tep  volts, 
for  no  apparent  cause.  Sometimes  our 
trouble  starts  at  the  begining  of  a  run 
with  or  without  load.  Some  days  we 
have  no  trouble  at  all,  while  on  other 
days  it  starts  out  without  trouble, 
but,  after  operating  for  an  hour  or 
two,  the  voltage  again  starts  to  fluctu- 
ate. We  have  given  the  commutator, 
brushes,  field  coils  and  armature  coils 
a  close  inspection  DUi  nave  found 
nothing  wrong.  I  would  be  much 
obliged  if  you  would  inform  me  as  to 
what  might  be  the  cause  of  our 
trouble.         J.  A.  A.  (new  Brunswick) 

The  information  given  is  not  complete 
enough  to  determine  definitely  the  cause 
of  your  trouble.  It  is  very  probable, 
however,  that  the  trouble  is  in  the  drive. 
Either  the  generator  speed  is  not  con- 
stant, or  else  it  is  too  high.  This  set  is 
belted.  If  the  belt  slips  the  generator 
speed  would  vary  and  fluctuations  of 
voltage  such  as  were  mentioned  would 
be  noted.  The  cure  in  this  case  would 
be  to  tighten  the  belt  or  supply  belt  dres- 
sing. The  speed  of  the  prime  mover 
may  drop  appreciably  as  the  load  comes 
on.  In  this  case  the  generator  voltage 
would  drop  as  the  load  comes  on,  but 
would  recover  when  the  load  is  thrown 
off.  This  action  is  liable  to  make  weld- 
ing very  difficult.  If  the  generator  is 
belted  to  an  electric  motor  the  generator 
may  be  driven  above  its  rated  speed  at 
times.  As  a  motor  heats  up,  its  speed 
increases.  Possibly  the  pulley  ratio  is 
such  that  the  generator  speed  at  starting 
is  correct.  After  running  a  while,  the 
motor  heats  up  and  the  speed  of  the  set 
rises.  With  the  speed  above  normal,  the 
generator  field  is  weakened  to  get  the 
rated  voltage.  Running  under  this 
weakened  field  the  generator  may  be 
somewhat  unstable.  The  action  then 
would  be  as  follows :  When  the  load  is 
thrown  on.  and  then  off,  the  final  voltage 
would  probably  not  be  the  same  as  the 
original.  Also  a  slieht  variation  in  the 
generator  speed  would  affect  the  voltage 
to  a  great  extent.  If  this  is  found  to  be 
the  trouble  change  the  pullev  ratio  to 
make  the  final  generator  speed  the  same 
as  rated.  s.  H. 

1908 — Failure  of  Electric  Car  Center 
Plates — What  is  the  cause  of  the 
failure  of  some  electric-car  center 
plates.  The  body  plate  is  of  malleable 
iron,  finished.  It  rests  on  a  finished 
brass  rine,  or  washer,  in  the  truck 
plate.  When  the  car  is  loaded,  the 
average  pressure  between  them  is  a 
little  over  iioo  pounds  per  sq.  in.  T 
suppose  as  they  wear  the  pressure 
tends  to  increase  toward  the  inside 
and  to  decrease  at  the  outside.  As  I 
understand  lubrication,  it  will  be  im- 
possible to  lubricate  these  plates  with 
oil,  even  though  they  are  supnlied  with 
oil  wells  and  grooves.  In  the  case  of 
plates  which  have  not  broken,  the  sur- 


333 

face  of  the  brass  is  bright.  In  the 
cases  of  breakage  which  I  looked  into, 
the  downward-projecting  base  of  the 
body  plate  had  broken  away  from  its 
bolting  flange.  The  pocket  of  the 
truck  plate  seemed  to  have  had  no 
brass  washer:  the  bottom  of  the 
pocket  had  a  rather  rough  surface 
which  seemed  like  that  of  iron,  which 
could  not  be  cleaned  off  with  carbon 
tetrachloride.  It  could  be  scraped  off, 
however,  showing  the  brass  beneath. 
I  would  be  very  grateful  for  answers 
to  these  questions  (i).  If  a  finished, 
malleable  iron  surface  slides  over  a 
finished  brass  surface  with  a  pressure 
of  iioo  pounds  per  sq.  inch,  is  the 
abrasion  likely  to  be  so  severe  as  to 
leave  a  coating  of  the  iron  adhering 
to  the  brass?  (2)  What  would  be  the 
resistance  to  such  a  sliding  per  sq.  in.? 
(3)  What  is  a  safe  intensity  of  pres- 
sure to  allow  in  desigTiing  car  center 
plates  of  these  materials?  (4)  Is  lu- 
brication  practicable? 

G.  F.  s.   (mass.) 

I — Under  the  poor  lubrication  condi- 
tions existing  in  ordinary  electric  car 
center  pin  structures,  a  pressure  of  1 100 
lb.  per  sq.  in.  is  too  high  and  abrasion  is 
to  be  expected.  2 — The  coeflicient  01 
friction  is  indeterminate.  Before  cut- 
ting starts  and  with  fresh  lubricant 
forced  between  surfaces  it  will  be  very 
low,  say  not  over  five  to  ten  percent. 
As  abrasion  starts  it  will  rise  to  a  high 
figure,  dependent  upon  the  condition  of 
the  surfaces.  3— In  small  double  trvick 
locomotives,  unit  pressures  of  from  300 
to  360  pounds  per  sq.  in.  give  satisfac- 
tory results  with  steel  on  steel.  4— With 
pressures  of  300  to  360  pounds  a  fairly 
effective  lubrication  can  be  maintained. 
Oil  will  work  itself  over  the  surfaces, 
but  grease  has  to  be  introduced  under 
pressure.     Both  methods  are  used. 

c.  M.  E. 

1999 —  Potentiometer  Leads  — The 
writer  used  copper  wire  to  connect  the 
thermocouples  (imbedded  in  generator 
slots)  to  a  switchboard  potentiometer. 
I  was  told  that  the  wire  should  be  of 
the  same  material  as  the  wires  in  the 
thermocouples  imbedded  in  the  slots, 
when  a  noncompensating  potentio- 
meter is  used.     Is  this  true? 

J.  E.  M.    (MICH.) 

A  thermocouple  generates  an  e.  m.  f. 
which  is  dependent  upon  the  difference 
in  temperature  between  the  hot  and  cold 
junction.  If  copper  wire  is  used  to  con- 
nect the  themocouple  terminals  to  the 
potentiometer,  the  cold  junction  of  the 
thermoconple  will  be  at  the  point  of  con- 
tact between  the  thermocouple  and  the 
copper  leads.  The  temperature  readings 
will  then  be  in  error  by  an  amount  equal 
to  the  difference  in  temperature  between 
this  cold  junction  and  the  temperature 
of  the  potentiometer,  as  indicated  by  its 
thermometer.  T.  S. 


CORRECTIONS 


In  the  Journal  for  January  1021,  p. 
15,  the  caption  to  Fig.  3  should  read 
70.7  percent  in  place  of  70.0.  On  p.  16, 
the  fraction  in  the  first  column  of 
Table  I   should  be  inverted  and  should 

read  -^7^. 


334 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  7 


THE 
ELECTRIC 
JOURNAL 


The    purpose    of   this    section    is    to    present 

accepted  practical  methods  used  by  operating 

companies   throughout    the   country 


The   co-operation   of  all   those   interested   in 

operating  and  maintaining  railway  equipment 

is    invited.      Address    R.    O.    D.    Editor. 


Stopping  a  Car  by  Braking  with  the  Motors 


Electric  braking  or  "dynamic  braking"  as  it  is  generally 
known  is  the  indirect  cause  of  a  number  of  troubles  supposed 
to  be  inherent  with  electric  railway  motors..  It  is  one  of  the 
causes  of  flashing,  pitting  of  commutators  and  in  some  cases 
broken  armature  shafts  and  other  mechanical  failures.  Burn- 
ing of  the  reverser  and  other  fingers  and  contacts  occurs  when 
the  control  is  thrown  off  in  the  midst  of  a  dynamic  breaking 
period.  A  great  number  of  reverser  failures  have  been  traced 
to  this  source  and  in  some  cases  reversef  finger  burning  has 
been  practically  eliminated  by  careful  attention  to  the  use  of 
the  dynamic  braking   feature. 

HOW  DYNAMIC  BEAKING  IS   OBTAINED 

In  order  to  set  up  a  dynamic  braking  condition,  the  connec- 
tions must  be  such  that  the  motors  will  act  as  generators  em- 
ploying the  momentum  of  the  car  as  a  prime  mover.  To  ob- 
tain this  condition,  the  field  connections  must  be  reversed,  with 
respect  to  the  armatures,  from  the  connections  set  up  for 
normal  running.  This  is  done  by  moving  the  main  drum  of 
the  controller  to  the  "off"  position,  and  moving  the  reverser 
drum  to  the  reverse  position,  if  the  car  is  running  forward,  or 


,  Direction  of  Armature  Current 
'  Direction  of  Field  Current  and  Field  Flux 
Direction  of  Circulating  Current 

-Electro-Motive  Force  of  Armature 


to  the  forward  position  if  the  car  is  running  backwards.  If 
the  car  is  headed  uphill  and  starts  to  roll  backwards,  it  is  un- 
necessary to  move  the  reverser  drum. 

In  addition  to  setting  up  the  proper  connections  of  the 
fields  in  relation  to  the  armatures,  a  loop  circuit  is  necessary. 
On  four  motor  equipments,  the  loop  is  always  in  existence,  but 
on  two  motor  equipments,  it  must  be  set  up  by  means  of  the 
main  drum  of  the  controller  which  is  moved  to  one  of  the 
liarallel  notches. 
CONDITIONS  INVOLVED  IN  A  DYNAMIC  BEAKING  SET-UP 
Figs.  I.  2  and  3  show  the  changes  in  connection  from 
normal  running  to  dynamic  braking.  Fig.  i  shows  the  normal 
running  set  up  for  the  series  position  of  the  controller.  The 
series  position  is  chosen,  as  the  diagram  is  somewhat  simpler 
than  the  parallel  and  the  conditions,  as  far  as  the  changeover 
of  circuits  to  obtain  braking  is  concerned,  are  the  same.  In 
each  case  the  circuit  breaker  is  open.  If  it  is  not  opened  by 
hand,  it  will  be  opened  by  the  heavy  rush  of  current  from  the 
line  when  the  main  drum  of  the  controller  is  moved  to  the 
parallel  position  after  the  reverser  has  been  thrown.  Fig.  2 
shows  the  set-up  momentarily  when  the  loop  between  the  two 


motors  has  been  closed.    Fig.  3  gives  the  final  set-up  when  the 
motors  are  braking. 

The  counter-electro-motive  force  is  the  voltage  which  is 
set  up  in  any  motor  in  opposition  to  the  line  or  trolley  voltage 
due  to  the  armature  conductors  cutting  the  field  flux. 

The  residual  voltage  is  the  voltage  set  up  at  the  armature 
terminals  (the  brushes)  by  the  residual  magnetism  of  the  pole 
pieces  when  no  current  is  flowing  in  the  field  coils. 

The  arrows  in  Fig.  i  show  the  direction  of  the  current  and 
the  electro-motive  forces  in  normal  running.  The  arrow  indi- 
cating the  direction  of  current  in  the  fields  also  indicates,  in  an 
indirect  way,  the  direction  of-  the  flux  through  the  poles  of 
the  motor. 

In  Fig.  2  the  armatures  and  fields  are  drawn  in  the  same 
relative  position  as  in  Fig.  I,  but  the  field  connections  have 
been  reversed  and  the  loop  between  the  two  motors  complet- 
ed. It  will  be  noted  that  the  direction  of  the  arrows  is  the  same 
as  shown  in  Fig.  i.  This  is  done  to  indicate  the  condition  just 
as  the  loop  is  completed  and  before  the  dynamic  action  has 
started. 

The  arrows  in  Fig.  3  show  the  direction  of  the  current  and 
the  electro-motive  forces  after  the  dynamic  braking  is  under 
way.  The  direction  of  the  arrows  in  motor  No.  2  has  been 
changed. 

WHAT   CAUSES   THE   MOTORS   TO   GENERATE 
There   is   one   underlying   principle   in   the   construction   of 
railway  motors  which  permits  dynamic  braking  under  the  con- 
ditions  noted  in   Figs.  2  and  3.   That  is,  no  two  motors  can 
be  built  exactly  alike  in  every  detail. 

When  the  power  is  shut  off  while  the  motors  are  running 
under  the  conditions  as  shown  in  Fig.  I,  the  direction  of  the 
flux  of  the  fields  due  to  the  residual  matrnetism  will  be  as 
shown  by  the  arrows.  In  Fig.  2  the  counter-electro  motive  forces 
and  currents  are  in  the  same  direction  as  shown  in  Fig. 
I,  hence,  the  flux  of  the  fields  are  in  the  same  direction.  It  is 
assumed  that  the  construction  of  motor  No.  i  is  such  that  the 
residual  magnetism  builds  up  a  higher  voltage  in  the  armature 
than  motor  No.  2.  The  voltage  generated  by  each  motor  will 
be  momentarily  in  the  same  direction  as  the  counter-electro- 
motive forces  shown  in  Figs.  \  and  2. 

The  higher  voltage  generated  by  motor  No.  i  will  force  a 
current  to  flow  through  the  loop  and  through  the  armature 
of  motor  No.  2  against  the  lower  residual  voltage,  as  shown  in 
Fig.  2.  This  current  flows  in  a  direction  which  tends  to  weak- 
en the  residual  field  of  motor  No.  2  and  sfrensthen  the  field 
of  motor  No.  I.  During  this  short  period,  illustrated  in  Fig.  2, 
motor  No  i  runs  as  a  generator  driven  by  the  momentum  of 
the  car  and  furnishes  power  to  motor  No.  2  which  tends  to 
drive  the  car  in  the  original  direction.  However  the  current 
flowing  through  the  field  of  motor  No.  2  wl!  quickly  over- 
come its  residual  field  and  build  up  a  field  in  the  opposite  di- 
rection. This  will  reverse  the  armature  voltage  and  cause  mo- 
tor No  2  to  run  as  a  generator  which  will  force  current  to 
flow  in  the  loop  circuit  in  the  same  direction  as  the  current 
generated  by  motor  No.  I.  Since  both  machines  are  now  run- 
ning as  generators  in  series  connection,  short  circuited  on 
themselves  and  both  generating  current  in  the  same  direction, 
the  current  in  the  loop  circuit  will  keep  on  building  up  until  a 
balance  between  the  motor  voltage  and  resistance  of  the  cir- 
cuit is  reached. 

WHY    CARE    SHOULD    BE   EXEECISED    IN   USING    THE   DYHAKIC 
BRAKE 

Due  to  the  low  resistance  of  the  loop  circuit  and  the  rela- 
tively high  saturation  of  the  magnetic  circuits  possible  with 
relatively  high  speeds  of  the  armatures,  very  heavy  currents 
are  obtained.  These  currents,  reaching  a  high  value  m  a 
short  period  of  time,  cause  sudden  shocks  to  the  electrical  and 
mechanical  parts  of  the  running  gear.  As  stated  previously, 
flashing  at  the  commutators  occurs,  and  heavy  strains  are 
placed  on  the  shafts,  pinions  and  gears. 

It  is  only  under  extreme  emergency  conditions,  therefore, 
that  dvnamic  braking  should  be  used. 

H.  R.   MEYER. 


The  Electric  Journal 


VOL.   XVIII 


AUGUST,    1921 


No.  8 


The  popular  conception  of  stabiliz- 
The  Gyro  '"g    ^    great    trans-Atlantic    liner    is 

Stabilizer  entirely     erroneous.     There     is     in- 

fer Ships  evitably  pictured  a  titantic  contest  of 

the  great  rolling  mass  of  the  ship  in 
the  grip  of  something  potentially  as  gigantic,  struggling 
to  subdue  part  of  its  motion.  This  conception  also 
affords  an  explanation  of  the  enormous  stresses  that 
are  supposed  to  be  involved  in  the  process. 

Now  this  is  not  at  all  true;  it  is  much  easier  and 
simpler.  We  do  not  reduce  the  roll.  We  suppress  it 
utterly  by  dealing  only  with  beginnings.  All  rolling  of 
ships  is  a  gradual  accumulation  of  individual  wave  in- 
crements. The  slight  extent  to  which  any  single  wave 
rolls  a  ship  is  now  well  understood  and  all  that  is  re- 
quired is  a  comparatively  small  gj'roscope  that  is 
capable  of  completely  quenching  this  single  increment. 

A  little  gyro  feeler  or  "control  gyro",  detects  the 
incipient  roll  at  its  beginning  and  also  shows  its  direc- 
tion. This  is  the  crux  of  the  whole  cycle;  the  rest  is 
easy.  Through  a  relay  and  motor,  the  large  gyro  is 
artificially  precessed  and  delivers  stresses  of  opposite 
sign  to  the  ship. 

To  anticipate,  however,  one  must  apply  the 
counter  moments  simultaneously  to  their  being  re- 
ceived from  the  sea.  This  would  be  impossible,  were 
it  not  for  the  slow  period  of  the  ship  itself,  which  gives 
an  abundance  of  time  to  get  precession  under  way  and 
deliver  the  counter-stresses  within  the  half  period,  con- 
tinuing until  the  ship  has  actually  been  given  a  coun- 
ter incipient  roll,  whereupon  the  electric  contact  in  the 
control  gyro  is  broken,  indicating  that  that  particular 
wave  has  been  fully  countered;  meanwhile  the  ship, 
having  received  equal  stresses  of  opposite  sign, 
never  starts  to  roll.  This  process  involves  not  only  a 
relatively  small  apparatus,  but  entails  merely  a  trifling 
stress  in  the  hull,  that  due  to  a  single  wave  increment 
only,  involving  stresses  of  .from  one-sixth  to  one- 
tenth  those  present  in  a  rolling  ship. 

To  produce  a  ship  that  never  rolls,  regardless  of 
weather  conditions,  becomes  thus  .\n  extremely  simple 
matter.  The  disappearance  of  roll  is  accompanied  by 
a  most  satisfactory  suppression  of  pitch.  On  most 
headings,  more  than  60  percent  of  the  pitch  disappears 
with  the  roll.  An  astonishing  difference  in  headway 
also  exists  between  a  stabilized  and  unstabilized  ship, 
repeated  records  showing  between  10  and  12  percent. 
Recently  the  Lyndonia,  a  100  percent  stabilized  ship, 
showed  14  percent  gain,  with  the  same  full  steam 
ahead,  same  weather  conditions  and  same  heading  ex- 
actly. The  importance  of  such  a  substantial  gain 
cannot  be  neglected.  It  has  been  found  through  work 
done  last  autumn  by  Commander  McEntee  at  the 
Naval    Basin    and    other    correlated    results    since    ob- 


tained, that  the  stabilizer  will  make  a  saving  of  up- 
ward of  30  percent  in  heavy  weather. 

We  are  often  asked,  "Can  large  ships  be  stabi- 
lized?" The  gyro  stabilizer  seems  to  be  fitted  by  na- 
ture to  deal  with  large  ships.  The  stabilizing  strength 
varies  as  the  sixth  power  of  the  size.  For  example,  a 
gyro  twice  the  size  of  another,  would  have  to  rotate  at 
only  one-half  the  speed  of  the  smaller  one  to  stabilize 
a  ship  64  times  the  size,  i.  e.,  64  times  the  total 
periodic  mass  moments  can  be  handled  at  a  cost  and 
weight  of  less  than  nine  times. 

The  stabilizer  is  coming  into  its  own.  The  gyro 
causes  pounds  easily  to  deliver  tons  of  useful  torque. 
Not  only  does  it  relieve  the  ship  of  all  major  stresses 
;ind  increase  its  life,  but  it  imparts  marvelous  comfort 
to  the  passenger  carrier.  Every  voyage  is  a  fair 
weather  voyage — the  occupants  never  seem  in  the 
slightest  to  realize  their  blessings  until  the  stabilizer 
(precession  motor)  is  turned  off  for  two  or  three 
minutes  to  ascertain  the  true  storm  conditions  and  ob- 
tain records.  After  that — well,  it  is  usually  difficult  to 
obtain  permission  to  take  another  rolling  record.  Sta- 
bilizing prevents  the  serious  depletion  of  cattle  and 
horses  in  live  stock  ships.  Through  a  variety  of  other 
important  economies  to  which  it  directly  contributes, 
it  constitutes  a  definite  dividend  payer  of  large  mag- 
nitude, paying  for  itself  in  a  comparatively  few  trips. 

E.  A.   Sperry 


Question 
Box 


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i  iV 


Oyro 


SCOpK 


on  the  S.  Y. 


ALEXANDER  E    SCHEIN 

Engineering  Div., 
Sperry  Gyroscope  Companj' 


WHEN    the    Lyndonia    left    the     Consolidated 
Ship    Building   Company   at   New   York  for 
her  maiden  voyage  up  the  Eastern  Coast  last 
summer,  she  was  hailed  among  yachtsmen  as  the  most 
beautiful  creation  of  the  times.     She  is  a  masterpiece 
of    the   naval    architect,   yacht   builder,    and    engineer. 
No  expense  has  been  spared  to  provide  her  with  the 
latest    improvements    in    design    and    equipment.     Her 
machinery,  rigging,  interior  fittings,  or  navigational  in- 
struments are  of  the  latest  type  and  altogether  reliable. 
During  the  winter  just  passed  there  was  added  as  part 
of  her   regular   equipment   a   machine    which    has    re- 
ceived    considerable     publicity     in     ncw^i.aiifr-.     .-md 
monthly    periodicals  during 
the  last  few  months.     This 
is   the   g}'roscopic   ship  sta- 
bilizer.    There    is  unfortu- 
nately much  mystery  about 
the  properties  of  the  gyro- 
scope and  the  mention  of  a 
gyroscopic     ship     stabilizer 
brings    up    varied     concep- 
tions as  to  just  what  it  is 
and     what     it     does.      The 
general    opinion    is    that    it 
prevents     seasickness,     and 
gives  comfort  to  the  pass- 
engers.    There     are     how- 
ever    many     other    reasons 
why  it  is  desirable  to  keep 
our  ships  on  an  even  keel, 
in   fact   the  necessity  of   a 
stabilized  •  vessel     is     now 
clearly  recognized. 

In  the  first  place,  why  does  a  ship  roll  ?  Everyone 
agrees  that  waves  cause  a  vessel  to  roll,  but  to  get  a 
firm  understanding  of  the  relation  the  stabilizer  has  to 
the  vessel's  roll,  we  must  investigate  a  little  further. 
It  is  one  of  the  common  beliefs  that  the  stabilizer  ex- 
erts tremendous  forces  on  the  ship  and  subjects  it  to 
great  strains.  An  understanding  of  the  following 
simple  explanation  will  dispel  all  doubts  about  the 
small  magnitude  of  the  forces  necessary  to  stabilize  a 
ship. 

Let  us  assume  a  ship  to  be  on  even  keel  and  mo- 
tionless, and  a  wave  approaches  broadside  as  in  Fig. 
2.  The  center  of  gravity  of  the  ship  remains  fixed  arid 
the  weight  of  the  ship  is  represented  by  the  force  IV 
acting  down.  But  as  the  waves  approach,  the  center 
of   buo\'ancy   shifts   towards   the   wave   crest,   because 


FIG.   I — THE  STE.AM  YACHT  LYNDONIA 


more  of  the  vessel  is  immersed  on  that  side,  and  the 
buoyant  force,  which  is  equal  to  W,  acts  upward  and  is 
represented  by  B.  It  is  evident  that  there  is  a  couple 
tending  to  turn  the  ship  and  make  it  roll  in  the  direc- 
tion of  the  arrow.  After  the  wave  has  passed  to  the 
other  side  of  the  ship  and  is  traveling  away,  the  couple 
will  be  acting  in  the  opposite  direction  and  the  boat 
will  tend  to  roll  back.  A  series  of  these  waves  would 
cause  the  ship  to  roll  more  and  more  each  time.  No 
one  wave,  however,  can  impart  any  great  amount  of 
rolling  to  a  vessel,  because  the  effective  wave  slope, 
which  is  the  factor  disturbing  the  vessel's  stability,  is 
so  small.  The  maximum  roll  increment  due  to  any  one 
wave  may  be  from  three  to 
six  degrees  depending  upon 
the  type  of  ship  and  size  of 
wave,  among  other  things. 
Fig.  3  shows  some  rolling 
records  taken  on  a  gyro- 
scopic recorder.  They 
show  quite  clearly  the 
gradual  building  up  of  the 
roll.  If  the  period  of  roll 
of  the  ship  is  quite  different 
from  the  period  of  the 
waves,  there  will  be  a 
Kuilding  up  of  roll,  and  a 
L,'iadual  reduction  of  roll  at 
frequent  intervals,  a  phe- 
nomenon that  in  reality  ex- 
ists. It  it  were  not  for  this 
condition,  the  synchronism 
of  the  natural  period  of  roll 
and  the  period  of  the  dis- 
turbing impulses  due  to  the  waves  would  soon  build  up 
Ti  dangerous  degree  of  rolling. 

There  are  many  unfavorable  effects  of  free  roll- 
ing. It  is  harmful  to  the  ship  structure.  It  causes 
severe  stresses  in  the  foundation  of  the  machinery, 
boilers,  stacks,  superstructures  and  other  heavy  paVts. 
The  pounding  of  waves  against  the  vessel's  side  is  due 
to  the  waves  being  out  of  phase  with  the  vessel's  roll. 
There  are  other  curious  effects  of  rolling.  A  combi- 
nation of  roll  and  pitch  causes  yaw.  which  makes  it 
very  difficult  to  handle  the  ship  and  keep  it  on  the 
proper  course.  The  steering  engine  is  in  continuous 
use  when  yawing,  and  this  is  a  twofold  waste  of 
power,  to  a  small  degree  in  the  steering  engine  itself, 
and  to  a  very  large  extent  in  the  main  propulsion  en- 
sines,  which  have  to  drag  the  rudder  through  the  water 


August,   1921 


THE  ELECTRIC  JOURNAL 


337 


when  it  is  at  some  oblique  angle.  Recent  tests  con- 
ducted by  Commander  William  McEntee  at  the  Wash- 
ington Navy  Yard  Tank  show  that  a  ship  requires 
about  one  percent  additional  power  for  every  degree 
roll — the  extra  power  being  necessary  to  maintain  the 
same  speed  as  if  the  ship  were  not  rolling.  All  cap- 
tains who  have  sailed  with  the  stabilizer  agree  that  tHey 
have  been  able  to  steer  straighter  courses  and  at  faster 
speeds  and  with  less  helm  with  the  stabilizer  running 
than  without  it.  On  the  run  up  from  the  West  Indies 
this  spring  the  Lyndonia  increased  her  speed  1.5  knots 
by  running  the  stabilizer  and  cutting  the  roll  down 
from  a  total  of  30  to  3.5  degrees.  The  recording  chart 
of  the  gyroscopic  compass  showed  less  deviation  from 
the  course,  and  the  helmsman  reported  practically  no 
use  of  the  rudder,  whereas  previously  it  had  been  a 
severe  physical  strain  to  stand  watch  at  the  wheel.  The 
economic  advantages  of  the  stabilizer  are  therefore 
ver}'  important,  to  say  nothing  of  the  comfort  assured 
to  the  passengers  and  ship's  personnel.  Rolling  also 
decreases  the  efficiency  of  the  propellers  because  of  the 
tendency  toward  air  cavitation  on  rolling  vessels,  espe- 
cially those  with  twin  or  triple  screws. 


FIG.  2 — EFFECT  OF  W.WE  ON  SHIP 

The  advantages  of  a  stabilized  ship  were  recog- 
nized early.  Perhaps  due  to  her  maritime  interests. 
Great  Britain  was  the  first  to  investigate  the  possibili- 
ties of  ship  stabilization.  There  appeared  at  various 
times  inventions  which  involved  the  shifting  of  heavy 
weights  back  and  forth  over  the  deck  to  counteract  the 
effects  of  the  waves.  The  shifting  was  controlled  by 
hydraulic  pistons,  valves  and  other  devices  and  it  was 
found  that  roll  could  be  prevented  somewhat,  but  that 
the  large  masses  moving  in  the  proper  direction  at  the 
proper  time  required  delicate  control  mechanisms 
which  were  quite  impracticable.  Later  there  appeared 
the  Framm  Tanks, — U  shaped  vessels  that  extended 
down  the  sides  of  the  ships  and  were  connected  at  the 
bottom.  They  were  partially  filled  with  water  which 
moved  within  the  tanks  from  one  side  to  the  other  and 
counteracted  the  waves.  The  movement  of  the  wafer 
was  controlled  by  valves,  operated  either  by  hand  or 
mechanically  and  automatically,  but  it  was  found  next 
to  impossible  to  keep  the  proper  relation  between  the 
ship's  roll,  the  period  of  the  waves,  and  the  period  of 
the  water  in  the  tanks,  and  that  unless  the  exact  rela- 
tion   was   maintained   the    rolling   would    often   be    in- 


creased rather  than  decreased.  It  is  interesting  to  note 
to  what  extent  space  and  weight  was  devoted  to  sta- 
bilizing apparatus  in  past  years.  The  present  gyro  sta- 
bilizer weighs  only  a  small  percentage  of  the  ship's 
weight  and  takes  but  a  fraction  of  the  space  of  the 
Framm  Tanks  and  other  stabilizer  devices.  Framm 
Tanks  may  still  be  seen  on  some  of  the  large  liners 
coming  into  New  York  Harbor.  They  are  not  used 
and  are  only  so  much  waste  space.  Among  the  simp- 
lest ideas  to  decrease  roll  was  the  bilge  keel  which  is  a 
fin-like  projection  extending  along  the  sides  of  the 
ship  below  the  water  line.  Bilge  keels  are  put  on  al- 
most every  vessel  launched  and  are  quite  effective  in 
decreasing  roll  when  the  vessel  oscillates  through  large 
angles,  say  down  to  a  total  arc  of  ten  degrees;  below 
this  angle  their  effect  could  be  overlooked  altogether 
as  their  effectiveness  is  only  proportional  to  the  square 
of  the  velocity  of  roll.  They  are  considerable  drag 
on  the  main  propulsion  engines,  the  power  consunip- 
tion  due  to  bilge  keels  being  at  least  three  percent  of 
the  total  power  of  propulsion,  even  under  the  best  con- 
ditions of  trim,  and  with  no  pitching.  The  power 
losses  of  bilge  keels  in  rough  weather  often  reach  as 
high  a  value  as  eight  percent.  A  vessel  equipped  with 
a  gyroscopic  stabilizer  permit.*  the  elimination  of  bilge 
keels, — the  power  saving,  even  in  calm  weather,  by 
their  elimination  being  considerably  more  than  that  re- 

r   31  Rolls- ISO  Seconds- 


Q-  5  25  dcgrefs 
FIG.  3 — ROLLING  RECORDS  TAKEN  ON  A  GYROSCOPIC  RECORDER 

quired  for  the  stabilizer  in  the  roughest  weather. 
Needless  to  say  bilge  keels  were  not  put  on  the  Lyn- 
donia. 

There  next  appeared,  almost  simultaneously  the 
passive  and  active  type  gyro  stabilizers.  The  passive 
type  was  invented  by  Dr.  Schlick.  It  was  called 
"passive"  because  it  was  not  effective  until  the  roll  of 
the  ship  was  large  enough  to  "precess"  the  gyro.  It, 
therefore,  could  not  decrease  all  of  the  roll  due  to  its 
sluggishness,  but  it  was  a  long  step  forward.  The 
great  weights,  and  large  space  requirements  of  the  old 
type  stabilizers  were  replaced  by  a  comparatively  small 
wheel,  the  weight  and  eft'ectiveness  of  which  were  mul- 
tiplied by  the  speed  of  rotation  and  the  speed  of  pre- 
cession. 

The  Active  Type  Stabilizer  was  invented  by  Mr. 
Elmer  A.  Sperry  of  New  York  and  was  a"  very  great 
improvement  over  the  passive  type  in  that  it  introduced 
ingenious  controls  which  enable  the  stabilizer  to  be- 
come operative  a  fraction  of  a  second  after  roll 
started;  and  the  result  is  that  roll  can  be  decreased  to 
very  small  angles.  For  practical  purposes  minimum 
stabilized  roll  less  than  two  degrees  total  arc  is  not  at- 
tempted. 

So  much  for  the  history  of  ship  stabilization.  The 
fundamental    principle    of    the   gyro    stabilizer    is    that 


338 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


action  of  a  g^Toscope  known  as  precession.  Only  a 
brief  explanation  will  suffice  to  enable  the  reader  to  un- 
derstand the  action  of  the  gyro  stabilizer. 

Fig.  4  shows  a  simple  gyroscope  which  will  illus- 
trate the  principle  of  the  stabilizer.  It  consists  of  a 
rapidly  spinning  wheel  with  axis  vertical,  mounted  in 
pivot  bearings  within  a  vertical  ring.  There  are  two 
trunnions  on  this  ring  forming  a  horizontal  axis  A'}  . 
If  the  trunnions  X  and  Y  are  mounted  in  bearings  the 
whole  mass  is  then  free  to  turn  about  the  horizontal 
axis  XY.  Imagine  the  wheel  to  be  spinning  in  the  di- 
rection of  the  arrow  on  its  rim,  and  that  we  apply 
forces  at  X  and  Y.  The  effect  would  be  to  turn  the 
whole  mass  about  a  third  axis  MN.  But  just  here  is 
where  the  gyroscopic  effect  comes  in.  If  we  assume 
that  the  wheel  is  of  sufficient  size  we  can  represent 
forces  X  and  Y  by  two  people,  one  of  whom  attempts 
to  lift  at  X  and  the  other  depress  at  1'.  There  will  be 
two  very  evident  effects  due  to  gyroscopic  action.  The 
first  to  be  noticed  is  the  great  resistance  the  gyroscope 
offers  to  any  effort  to  turn  it  about  the  axis  MN  by 
means  of  forces  X  and  Y.  The  second  effect  is  that 
point  A  will  be  seen  to  move  away  from  us,  and  point 


gyroscope  resists  it  by  forces  at  X  and  Y,  and  at  the 
same  time  precesses  about  the  axis  XY.  If  the  direc- 
tion of  roll  reverses  the  forces  will  also  reverse  and 
so  will  the  precession  about  XY.  The  g>'ro  automatic- 
ally exerts  forces  in  the  proper  direction  and  it  is  con- 
tinually oscillating  back  and  forth  on  the  XY  axis.  In 
a  general  discussion  about  the  ship  stabilizer  the  turn- 
ing movement  of  the  gyro  is  known  as  precession,  al- 
though as  defined  above  precession  strictly  takes  into 
consideration  the  forces  acting.  In  this  article  preces-  ' 
sion  will  be  taken  to  mean  the  angular  motion  of  the 
gyro,  and  when  the  forces  are  referred  to,  the  term  will 
be  gyroscopic  force  or  gyroscopic  moment.  This 
separation  of  the  two  actions  simplifies  the  discussion 
and  is  the  common  practice  when  speaking  of  stabil- 
izers. 

In  Fig.  5  is  shown  the  simplest  form  of  ship  sta- 
bilizer. In  actual  design  the  rotating  wheel  or  rotor, 
is  mounted  in  bearings  and  enclosed  in  a  casing.  On 
this  casing  there  are  two  gudgeons  corresponding  to 
points  X  and  Y  through  which  the  forces  are  trans- 
mitted   to    the    ship.     It    remains    only    to    limit    these 


FIG.  4— SIMPLE  GYRO  TO  ILLUSTRATE  PRECESSION 


B  towards  us  about  the  axis  XY.  These  two  actions 
together  are  known  as  precession.  One  is  never  pres- 
ent without  the  other.  In  order  to  have  resisting 
forces  we  must  have  angular  movement,  and  con- 
versely with  an  angular  movement  there  must  be 
forces.  It  will  be  noticed  that  there  are  three  axes 
involved  in  precession.  First  there  is  the  axis  of  spin, 
— :the  axis  about  which  the  wheel  rotates.  Secondly, 
there  is  the  axis  of  spin  at  right  angles  to  the  first, 
about  which  the  forces  act.  And  third  there  is  the 
axis  of  precession  about  which  the  gyro  turns  when 
forces  are  applied  about  the  second  axis.  This  third 
axis  is  perpendicular  to  each  of  the  other  two.  The 
first  axis  is  represented  in  Fig.  4  by  AB,  the  second  by 
MN,  and  the  third  by  XY.  Precession  may  therefore 
be  simply  defined  as  an  angular  movement  accom- 
panied by  a  resisting  moment,  both  of  which  are  at 
right  angles  to  the  axis  of  spin  and  to  each  other.  This 
principle  is  made  use  of  in  the  gyro  ship  stabilizer. 
Just  how  it  is  done  is  evident  from  Fig.  5,  which  shows 
the  same  gj'roscope  mounted  in  a  ship.  The  axis  MN 
is  now  the  axis  about  which  the  ship  rolls.  As  soon 
as  there  is  any  angular  movement  due  to  rolling,  the 


FIG.  5 — ELEMENTARY  FORM  OF  SHIP  STABILIZER 

forces  so  that  they  will  not  be  excessive  and  cause  un- 
due stresses  in  the  hull.  The  well  known  formula  for 
g^TOSCopic  moment  is : 


;1/  = 


307 


where  k-W  is  the  moment  of  inertia  of  the  rotor,  R  is 
the  revolutions  per  minute  of  the  rotor  and  «  is  the 
angular  velocity  of  precession  in  radians  per  second. 
The  moment  will  be  in  foot-pounds.  If  we  omit  the 
complexity  of  mathematical  expressions  the  above 
moment  is  approximately  equal  to  the  tilting  moment 
produced  by  the  maximum  effective  wave  slope,  and  if 
such  a  moment  were  applied  to  a  non  rolling  ship  dur- 
ing the  period  of  oscillation  it  would  cause  the  ship  to 
roll  an  amount  about  equal  to  the  maximum  roll  incre- 
ment. The  stabilizing  moment  is  therefore  only 
slightly  greater  than  the  natural  effect  of  the  waves 
causing  the  ship  to  roll,  and  in  the  case  of  the  Lyn- 
donia  is  only  about  375  000  ft.  lbs. 

From  the  formula  it  is  seen  that  we  can  control 
the  magnitude  of  the  gyroscopic  moment  by  varying 
either  R  or  n.  It  would  be  impossible  to  vary  R 
quickly  and  easily.     But  with  R  constant  it  is  an  easy 


August,  1921 


THE    ELECTRIC   JOURNAL 


339 


matter  to  vary  n  and  hence  M.  Stabilizers  are  there- 
fore designed  for  some  known  value  of  R  which  will 
not  overstress  the  wheel,  and  the  gyroscopic  forces 
transmitted  to  the  ship  are  limited  by  limiting  the  speed 
of  precession  by  mechanical  brakes  or  other  means. 
This  type  of  stabilizer  is  known  as  the  passive  gyro 
stabilizer.  It  uses  the  force  of  the  waves  to  start  gyro 
precessing,  and  mechanical  brakes  and  suitable  control 
pistons  and  levers  to  control  within  close  limits  the 
speed  of  precession.  Due  to  the  fact  that  the  mass  of 
the  casing  and  wheel  is  necessarily  large  it  takes 
several  seconds  to  get  the  speed  of  precession  up  to 
normal  velocity  and  therefore  the  ship  has  gained  con- 
siderable roll  before  full  stabilizing  is  obtained.  The 
passive  type  stabilizer  cannot  decrease  the  roll  to  less 
than  six  or  seven  degrees. 


FIG.   6— ROTOR   WITH    SHAFT   STUBS   BOLTED   IN    PLACE 

The  Active  Type  Gyro  Stabilizer  practically 
anticipates  the  waves  and  starts  stabilizing  when  the 
ship  has  barely  moved.  The  sensitive  element  that  is 
responsible  for  this  action  is  known  as  a  control  g>-ro. 
It  is  a  small  gyroscope  suitably  mounted  in  bearings, 
casing,  and  frame  which  does  not  weigh  over  150 
pounds  complete  for  even  the  largest  vessels.  The 
wheel  is  turned  by  an  electric  motor  at  five  or  six 
thousand  r.p.m.  The  whole  unit  can  be  made  so  sen- 
sitive that  it  will  indicate  the  ship's  roll  a  fraction  of  a 
second  after  the  roll  starts.  The  indication  of  roll  is 
transmitted  electrically  to  control  panels  which  oper- 
ate a  precession  motor.  This  motor  is  geared  to  the 
main  stabilizer  unit  and  starts  precession  of  this  unit 
immediately,  instead  of  waiting  for  the  waves  to  do  so. 


The  result  is  full  stabilizing  forces  about  1.5  seconds 
after  the  roll  starts  and  the  ship  can  be  stabilized  to  1.5 
or  two  degrees  roll  on  each  side  of  the  mean  position. 

The  following  paragraphs  cover  some  points  of 
the  technical  design  of  the  active  stabilizer  for  the 
steam  yacht  Lyndonia.  This  is  the  first  ship  to  re- 
ceive a  stabilizer  since  the  United  States  entered  the 
/World  War.  It  is  a  vessel  320  feet  long  overall,  30 
feet  beam,  and  displaces  about  iioo  tons.  The  normal 
speed  is  13  knots  with  two  triple  expansion  steam  en- 
gines. 

In  designing  a  stabilizer  for  a  ship  there  are  cer- 
tain characteristics  to  be  taken  into  account.  They 
are  displacement,  metacentric  height,  period  of  roll, 
and  roll  increment.  Displacement  is  expressed  in  long 
tons  of  2240  lbs.  each;  metacentric  height  is  expressed 
in  feet,  and  period  of  roll  in  seconds.  The  first  is 
easily  determined  from  the  ship  itself  or  from  its 
builders.  The  second  is  often  furnished  by  the  naval 
architect  but  must  be  determined  by  a  heeling  test  later. 
The  third  is  most  easily  determined  by  an  instrument 
known  as  the  Roll  and  Pitch  Recorder.  This  is  a 
gyroscopic  instrument  which  makes  a  graphic  record 
of  the  vessel's  roll  and  pitch  together  with  a  time  indi- 
cation by  means  of  which  the  period  of  roll  may  be 
estimated.  Fig.  3  shows  such  a  record.  The  curve  is 
that  of  the  vessel's  rolling,  and  the  bottom  line  with 
jogs  is  the  time  curve.  A  jog  occurs  at  every  ten  sec- 
onds interval.  The  period  may  be  estimated  by  count- 
ing off  a  number  of  complete  rolls  and  noting  the  time. 
Roll  increment,  which  was  the  fourth  item  above  is  the 
number  of  degrees  increase  in  roll  in  a  single  complete 
roll  of  the  ship.  An  example  of  roll  increment  is  given 
in  Fig.  3  at  the  point  marked  Q.  In  designing  a  sta- 
bilizer the  maximum  roll  increment  is  necessary  be- 
cause the  stabilizer  must  be  made  to  have  a  roll 
quenching  power  at  least  equal  to  the  maximum  roll  in- 
crement, or  full  stabilization  could  not  be  obtained. 
The  stabilizer  would  be  of  little  use  if  a  single  wave 
could  roll  the  ship  more  than  the  stabilizer  could  take 
care  of.  The  roll  quenching  power  depends  upon  the 
characteristic  product  D  T  H,  displacement  times 
period  times  metacentric  height.  The  following  char- 
acteristics were  assumed  for  the  Lyndonia  before  the 
ship  was  launched. 

D=iooo  tons 

T=7.s  seconds 

H=3.2  feet 
DTH=240OO=characteristic  product 
After  launching  with  the  stabilizer  in  place,  the  char- 
acteristics were  found  to  be 

D=II00  tons 

T^lO.5  seconds 

H=2  feet 
DTH^23000^characteristic  product 
The  original  figures  were  somewhat  in  error  but 
the  stabilizer,  which  was  designed  on  DTH  =  24000 
was  about  five  percent  oversize  according  to  the  final 
figures.  The  maximum  roll  increment  was  also  some- 
what smaller  than  expected  and  this  fact  provides 
further  margin  of  stabilizing  power. 


340 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


The  design  of  the  rotating  wheel  is  dependent  en- 
tirely upon  the  assumed  values  of  DTH  and  the  roll 
quenching  power.  In  the  case  of  the  Lyndonia  a  rotor 
with  k-WR  =  165000000  was  found  to  be  necessary. 
The  rotor  finally  designed  had  a  moment  of  inertia  of 
k'^W  =112  000  ft.^  lbs.  and  a  speed  of  rotation  of  i?  = 
1500,  giving  ^''rri?=i68  000  000.  Fig.  6  shows  the 
rotor  with  its  shaft  stubs  bolted  in  place.  There  are 
many  factors  entering  into  the  design  of  such  a  rotor. 
The  speed  of  rotation  is  limited  by  the  peripheral  ve- 
locity of  the  rim,  which  ought  not  to  exceed  32000 
feet  per  minute  or  the  windage  losses  will  be  exces- 
sive. The  shape  of  the  rim  and  web  section  is  an- 
other item  that  depends  upon  windage  and  stress  con- 
siderations. Tangential  fibre  stresses  at  full  speed  of 
rotation  are  not  over  12000  lbs.  per  square  inch.  The 
6.5  ft.  diameter  rotor  is  a  solid  steel  forging  and  the 
shaft   stubs   are  nickel   steel,   the  whole   rotating  ele- 


FIG.  7 — CONTROL  GYRO 

ment  as  shown  in  the  photograph  weighing  about 
22  000  lbs.  Needless  to  say  the  balance  of  such  a  unit 
must  be  of  the  highest  order  and  perfection.  The  bal- 
ance of  the  Lyndonia  rotor  was  made  on  a  machine 
built  and  designed  by  the  Westinghouse  Electric  and 
Aifg.  Company.  Remarkably  good  results  were  ob- 
tained on  this  machine. 

Coincident  with  a  good  balance  there  are  other 
precautions  which  must  be  observed  to  insure  th'e  suc- 
cessful operation  of  the  stabilizer.  The  journals  and 
bearings  have  specially  prepared  surfaces  and  their 
design  has  been  carried  to  an  extreme  degree  of  ac- 
curacy. The  large  gyroscopic  loads  could  not  be  car- 
ried on  any  type  of  bearing  which  is  common  practice 
today  in  similar  work, — that  is  with  the  same  pres- 
sures and  journal  speeds.  The  main  bearings  on  the 
stabilizer  in  question  carry  800  lbs.  per  square  inch  of 
projected  area  and  under  test  conditions  successfully 
carried  1000  lbs.  per  square  inch.  On  another  stabil- 
izer with  similar  bearings,  loads  of  1400  lbs  per  square 
inch  were  carried  successfully.     These  loads  gradually 


increase  from  zero  to  a  maximum  and  are  not  suddenly 
applied.  This  will  be  evident  from  consideration  of 
the  formula  for  gyroscopic  moment  which  varies  as  n, 
the  precession  velocity.  The  thrust  load  of  the  rotor 
is  carried  on  a  Kingsbury  bearing  which  gives  silent 
and  very  efficient  operation. 

On  the  left  in  Fig.  6  may  be  seen  one  of  the  gud- 
geon bearing  housings.  Two  of  these  bearings  form 
a  horizontal  axis  about  which  the  entire  casing  pre- 
cesses,  and  it  is  through  these  bearings  that  the  gyro- 
scopic stabilizing  forces  are  transmitted  to  the  ship 
structure.  These  are  roller  bearings  and  carry  a  maxi- 
mum load  of  68  500  lbs.,  consisting  of  the  gyroscopic 
force,  48000  lbs.  and  half  the  gyro  unit  weight, 
:30  500  lbs. 

In  the  same  photograph  may  be  seen  a  large  gear 
mounted  on  the  gyro  unit.  This  is  the  precession  gear 
which  meshes  with  a  worm  gear  reduction  unit  and 
through  which  the  speed  of  precession  is  controlled. 
The  precession  motor  is  connected  to  the  gear  train 
with  a  100  to  I  gear  ratio.  The  speed  of  precession 
of  the  main  g>'ro  depends  upon  the  period  of  roll  of 
the   ship.     The   total   arc  of   precession    for   full    roll 


M^IJ 


^^'f^^^fJ^^^:^^^^ 


L  Smbihzer  Off  ■*-  Stabilizer  On   —        Stabilizer  Off    — 

FIG.  8 — ROLLING  .\ND  ST.\BILIZING  CURVES  FROM  LYNDONIA 

(liienching  power  is  120  degrees;  60  degrees  each  side 
of  the  vertical.  The  g}'ro  must  be  made  to  precess 
through  this  arc  in  the  same  time  the  ship  rolls  from 
port  to  starboard,  or  starboard  to  port.  The  relation 
between  period  of  roll  and  velocity  of  precession  in 

r.p.m.  is  approximately  N  =  -j-.  In  determining  the 
velocity  of  precession  for  the  Lyndonia  stabilizer  a 
period  T  ^  9  seconds  was  assumed  with  a  variable 
range  to  cover  any  possibility  of  error  in  data.  With 
nine  seconds  period,  the  speed  of  precession  would  be 
y.T,  r.p.m.  corresponding  to  a  precession  motor  speed 
of  730  r.p.m.  In  Fig.  6  may  also  be  seen  the  me- 
chanical brakes  at  the  right  of  the  center.  These  are 
mounted  on  the  worm  shaft  also,  and  are  used  to  stop 
the  precession  quickly  at  the  end  of  the  precession  arc. 
The  stabilizer  equipment  is  practically  independ- 
ent of  the  ship  power.  A  steam  turbine-generator  set 
provides  all  electrical  power  necessar>-  to  operate  the 
equipment  except  for  small  excitation  and  control  gyro 
current.  The  gyro  may  be  brought  up  to  full  speed  in 
one  and  one-half  hours  depending  upon  the  current 
input  to  the  motor.  This  does  not  mean  that  the  sta- 
bilizer equipment  is  inoperative  for  1J/2  hours.  Sta- 
bilizing can  start  when  the  gyro  is  at  about  three- 
quarters  full  speed,  and  can  continue  while  the  gyro  is 
being  brought  up  to  speed.  The  precession  motor  is 
controlled  from  a  relay  starting  panel,  which   in  turn 


August,  1 92 1 


THE    ELECTRIC   JOURNAL 


341 


is  energized  by  the  action  of  the  control  gyro.  The 
control  gyro,  precession  motor  and  magnetic  brakes 
constitute  partly  the  controlling  device  which  distin- 
guishes the  active  and  passive  type  gyro  stabilizer. 

The  photograph  of  the  control  gyro.  Fig.  7  shows 
the  moving  contactor  which  completes  the  circuits  to 
the  relay  starting  panel  by  moving  left  and  right  as  the 
roll  of  the  ship  precesses  the  small  rotor.  This  rotor 
is  mounted  with  horizontal  axis  thwartships.  Roll  to 
port  or  starboard  will  therefore  cause  the  g>To  to  pre- 
cess  about  a  vertical  axis  to  port  or  starboard,  depend- 
ing upon  the  direction  of  rotation  of  the  wheel.  The 
control  gyro  is  the  sensitive  element  or  brain  of  the 
entire  equipment.  It  senses  the  roll  of  the  ship  a  frac- 
tion of  a  second  after  motion  starts  and  communicates 
the  direction  and  amount  of  roll  to  the  precession  mo- 
tor.    Immediately  the  main  gyro  exerts  its   forces  to 


FIG.  9— INTERIOR  VIEW   OF  STABILIZER  COMPARTMENT  ON  THE 
LYNDONIA 

prevent  the  roll,  irrespective  of  direction.  The  control 
gv'ro  never  makes  a  mistake  in  direction,  always  starts 
precession  about  a  half  second  after  roll  begins,  and 
stops  precession  about  a  half  second  before  roll  stops. 
The  control  gyro  and  the  other  control  mechanisms 
on  the  Lyndonia  are  sensitive  to  three  degrees  total 
roll.  -By  increasing  the  gyroscopic  effect  and  the  di- 
rective effect  of  the  control  gyro  it  would  be  possible 
to  stabilize  to  less  than  three  degrees  total  rolf,  pro- 
vided also  that  the  precession  motor  were  increased  in 
capacity  to  be  able  to  accelerate  the  main  gyro  more 
quickly.  This  however  is  not  necessary,  as  three  de- 
grees total  roll  is  almost  imperceptible  unless  one  is 
looking  for  it. 

There  are  many  interesting  features  of  the  stabil- 
izer on  this  yacht.  Being  as  it  is,  slightly  oversize,  it 
has  sufficient  capacity  to  handle  even  the  most  severe 


seas.  In  fact,  for  general  service,  it  is  run  at  about 
three-quarters  full  speed  of  the  rotor,  and  has  been 
found  to  give  entirely  satisfactory  results.  The  roll- 
ing and  stabilizing  records  taken  on  the  trial  trip  and 
reproduced  in  Fig.  8  were  obtained  with  three-quarters 
speed  of  the  gyro.  A  roll  of  thirty  degrees  was  re- 
duced to  four  maximum.  Even  if  the  roll  has  been 
very  much  greater  the  stabilizer  would  have  kept  the 
boat  within  the  same  limits.  It  matters  not  how  great 
the  roll,  if  the  stabilizer  has  a  roll  quenching  power 
greater  than  the  roll  increment  due  to  a  single  wave, 
it  will  gradually  reduce  that  roll  down  to  the  same 
small  amount.  And  it  will  do  this  without  applying 
any  more  than  the  normal  stabilizing  forces  to  the 
ship,  because  the  speed  of  precession  being  maintained 
constant,  the  gyroscopic  moment  must  also  be  con- 
stant. This  moment  is  perfectly  determinable,  and  the 
bearings,  gudgeons,  and  foundations  have  been  de- 
signed to  suit.  By  controlling  the  speed  of  the  gyro, 
the  operator  has  within  his  power  the  adjustment  of 
the  stabilizer  to  the  sea  conditions  which  is  an  im- 
portant  feature  because  it  means  a   saving  in   power. 

7  degrees       9  degrees 

Rolling''     /        ,-*  Natural  Dying  Down  Cuive 

Stabilizing'     / 
Rolling  Up 

FIG.  10 — ROLLING  CL'RVES  OF  THE  LYNDONIA  AT  ANCHOR  IN  STILL 
WATER 

The  Stabilizer  action  can  be  reversed,  rolling  the  ship,  in- 
stead of  stabilizing. 

About  90  percent  of  the  total  power  necessary  to  run 
the  stabilizer  is  used  in  spinning  the  rotor,  so  that 
even  small  changes  in  speed  mean  considerable  varia- 
tion in  power.  To  reduce  the  spinning  horsepower  as 
much  as  practical  the  rotor  is  run  in  a  fifteen  inch 
vacuum  maintained  in  the  casing  by  a  small  air  pump. 
At  full  speed  the  power  required  for  spinning  is  about 
ZZ  hp.  The  power  for  precession  is  almost  negligible, 
because  the  waves  tend  to  precess  the  gyro  naturally, 
the  only  power  necessary  being  that  required  to  assist 
the  waves  in  bringing  the  g\TO  up  to  full  speed  of  pre- 
cession and  this  does  not  average  over  four  hp. 

It  was  the  enthusiastic  report  of  Captain  Rich  and 
the  other  officers  of  the  Lyndonia  that  the  stabilizer 
did  all  that  was  expected  of  it.  At  no  time  were  the 
decks  ever  awash  as  long  as  the  stabilizer  was  in  op- 
eration, but  on  one  occasion  without  the  gyro  working, 
the  stern  rolled  under  and  shipped  two  feet  of  water. 
Steering  was  always  a  pleasure  when  the  yacht  was 
stabilized  and  the  equipment  is  now  considered  so  nec- 
essary that  they  never  leave  port  without  it  running. 


Th©  Cojistrtictlon  of  the  LyBcbBia  Siablll^ei^ 


THERE  was  a  time  when  tlie  stabilization  of 
ships  was  considered  solely  for  the  comfort  of 
the  passengers  and  the  ship's  personnel.  This 
truly  was  worth  considering  for  all  types  of  vessels, 
commercial,  naval  and  pleasure,  especially  in  the  later 
designs  of  vessels  which  have  been  built  for  speed,  re- 
sulting in  narrow  beams  and  fine  lines.  Today  many 
other  reasons  have  developed  why  a  vessel  should  be 
stabilized,  such  as  relieving  strains  in  the  ship's  struc- 
!iure  and  machiner\%  for  operating  the  ship  more  eco- 
nomically, for  maintaining  a  more  nearly  straight 
course  and  in  the  case  of  naval  vessels,  for  aiding  in 
gun  fire.  A  stabilizer  has  just  been  installed  on  the 
Yacht  "Lyndonia,"  the  purpose  of  which  is  primarily 
the  comfort  of  the  passengers. 

The  Lyndonia  stabilizer  consists  of  a  vertical  ro- 
tor made  up  of  a  solid  forged  steel  disc  wheel  6  ft.  6.5 
in.  diameter  having  a  rim  17.5  in.  wide  and  11  in. 
thick.  The  disc  portion  has  two  circular  flanges,  one 
on  each  side  to  which  are  attached  the  shaft  stubs.  On 
the  lower  stub  just  above  the  journal  is  mounted  a  spin- 
ning motor  which  revolves  the  rotor. 

The  entire  rotor  is  surrounded  by  a  casing  in  the 
shape  of  two  frustums  of  cones  with  their  bases  to- 
gether. The  main  portion  of  this  casing  is  made  up 
of  three  separate  steel  castings,  a  center  casing  or  belt 
which  encircles  the  rotor  rim  and  an  upper  and  lowcr 
casing  which  make  up  the  conical  sections.  It  is  in 
these  latter  sections  that  the  main  rotor  bearings  are 
carried.  These  bearings  as  well  as  the  journals,  which 
have  supported  loads  as  high  as  1200  lbs.  per  square 
inch  of  projected  area  at  a  journal  speed  of  50  feet 
per  second,  have  received  special  attention  in  regard  to 
machining  to  insure  safe  operation  under  these  loads. 
The  bearings  are  of  the  solid  spherical  seated  type  in 
order  to  provide  self-aligning  features  to  compensate 
for  the  shaft  deflection  between  the  rotor  and  journal 
as  the  stabilizer  is  precessed  and  the  gyroscopic  forces 
set  up.  In  connection  with  the  bearings  it  is  interest- 
ing to  note  the  conditions  under  which  they  operate. 
When  the  gyroscope  is  precessing  fore  and  aft,  the 
major  forces  act  athwartship  stabilizing  the  vessel ;  on 
the  other  hand  when  the  stabilizer  is  not  precessing, 
but  the  ship  is  rolling,  the  forces  act  fore  and  aft  tend- 
ing to  cause  the  vessel  to  pitch.  Thus  there  are  four 
major  bearing  surfaces  on  which  very  heavj'  loads  are 
imposed,  with  the  greater  ones  athwartship  due  to  the 
fact  that  the  stabilizer  precesses  at  a  greater  angu- 
lar velocity  than  the  ship  would  roll.  Naturally  when 
the  ship  is  rolling  heavily  and  the  stabilizer  is  spinning 
it  is  also  precessing,  thus  the  athwartship  section  of  the 
bearing  is  the  working  portion  that  is  in  use  most  of 
the  time.     With  these  facts  in  view  the  surface  of  the 


W.  T.  MANNING 

Turbine  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 

divided 


bearing  is  divided  into  four  sections  with  the  oil 
grooves  between  each  section.  Each  athwartship  sec- 
tion extends  through  an  angle  of  about  130  degrees 
and  each  fore  and  aft  section  through  aboui  30  degrees 
the  remaining  angle  being  taken  up  by  oil  grooves. 
Each  of  these  sections  were  scraped  separately.  Dur- 
ing the  first  run  with  these  bearings,  while  they  were 
being  worked  in,  a  diflFerence  of  oil  pressure  or  an  oil 
pressure  of  10  lbs.  above  the  vacuum  obtained  in  the 
casing  was  maintained  on  them  (The  entire  casing  and 
oiling  system  is  under  a  partial  vacuum  of  15  to  20 
inches).  With  this  condition  the  temperature  rise 
through  the  bearing  averaged  from  15  degrees  to  20 
degrees.  This  temperature  difference  existed  while 
the  g)TO  was  not  precessing  but  while  it  was  slightly 
inclined,  the  reaction  on  the  bearings  amounting  to  on- 
ly about  50  lbs.  per  square  inch  of  projected  area. 
This  load  however  was  actually  concentrated  on  a 
small  area  between  the  oil  grooves  in  the  fore  and  aft 
sections  of  the  bearing.  .\s  soon  as  precession  was 
started  and  the  loads  applied  to  the  usual  working  sur- 
faces, even  though  the  pressure  per  square  inch  of  pro- 
jected area  amounted  to  900  to  1000  lbs.,  the  tempera- 
ture rise  through  the  bearing  fell  off  to  10  degrees 
as  a  maximum.  This  was  due  primarily  to  the  fact 
that  there  was  a  large  bearing  surface  and  that  the 
pressure  was  first  on  one  side  of  the  bearing  and  then 
diametrically  opposite  as  the  unit  precessed  every  four 
seconds,  thus  affording  ideal  conditions  for  flushing 
the  working  surfaces  with  cool  oil. 

When  operating  at  speeds  above  75  r.p.m.  the 
weight  of  the  rotor  is  carried  by  a  Kingsbury  thrust 
bearing  at  the  bottom  of  the  lower  journal ;  at  speeds 
lower  than  this,  the  weight  is  transferred  to  a  ball 
thrust  bearing.  This  procedure  is  resorted  to  in  order 
not  to  wipe  the  Kingsbur>'  thrust  shoes  before  an  oil 
film  has  been  established  beneath  them. 

On  the  bottom  of  the  lower  casing  are  mounted 
the  caps  containing  the  thrust  bearings,  the  construc- 
tion of  which  is  shown  in  Fig.  i.  At  the  top  of 
the  left  hand  portion  of  this  figure  is  shown  the  mam 
rotor  journal  into  which  is  screwed  the  Kingsbur\- 
thrust  collar.  Below  this  collar  are  the  thru.st  shoes 
carried  on  two  leveling  plates.  Each  of  these  leveling 
plates  is  supported  on  a  knife  edge,  the  knife  edge  act- 
ing as  a  support  for  the  top  plate  being  at  right  angles 
to  that  for  the  bottom  one. 

Below  the  Kingsbury  thrust  bearing  is  the  ball 
thrust  bearing  which  is  used  when  starting  or  stopping 
the  rotation  of  the  stabilizer  wheel.  It  will  be  noted 
that  this  bearing  is  supported  from  the  bottom  of  the 
cap  on  a  free  sliding  piston.  When  the  weight  of  the 
rotor  is  to  be  transferred    from   the   Kingsbury   thrust 


August,  1921 


THE   ELECTRIC  JOURNAL 


343 


bearing  to  the  ball  thrust  bearing,  an  oil  pressure  of  ap- 
proximately 1005  lbs.  per  square  inch  is  built  up  in 
the  cylinder  below  the  piston  by  means  of  the  hand 
operated  hydraulic  jack  pump  shown  at  the  right. 
This  pressure  raises  the  ball  bearing  bodily  until  it 
comes  in  contact  with  the  upper  ball  race  after 
which  it  lifts  the  rotor  itself  to  the  extent  of  about 
0.005  inch  which  leaves  sufficient  clearance  between  the 
Kingsbury  thrust  bearing  shoes  and  collar  for  starting 
In  conjunction  with  these  hydraulic  features  it  will  be 
noted  on  the  outside  of  the  cylinder  there  is  a  large 
square  threaded  nut  which  in  turn  has  a  gear  cut  on 
its  periphery  that  meshes  with  a  small  pinion  controlled 
by  a  hand  lever  on  the  outside  of  the  cap.  As  the  ball 
bearing  is  being  jacked  up,  this  lever  is  swung 
around,  causing  the  nut  on  the  outside  of  the  hydraulic 
cylinder  to  follow  up  the  flange  of  the  piston.  The 
bearing  is  raised  until  the  outside  hand  lever  is  stopped 
by  a  lug  on  the  lower  cap.  When  the  lever  is  in  this 
position  the  ball  bearing  has  been  raised  sufficiently  to 
take  the  load  off  the  Kingsbury  bearing.  It  should  al- 
so be  noted  that  with  this  hand  lever  in  this  position 


trunnions  it  is  of  course  necessary  to  have  this  swivel 
joint  to  get  the  oil  from  an  oscillating  member  to  a 
stationary  member.  The  construction  of  this  swivel 
is  obvious  when  it  is  considered  that  all  portions  out- 
side the  roller  bearing  are  stationary.  It  is  this  out- 
side housing  that  is  bolted  to  the  ship's  structure  and 
through  which  the  gyroscopic  forces  are  transmitted 
from  the  gyroscope  to  the  ship. 

The  starting  of  the  precession  of  the  stabilizer  is 
accomplished  by  means  of  a  so  called  precession  mo- 
tor and  a  precession  gear.  The  precession  gear  is  a 
double  reduction,  the  first  being  through  a  worm  and 
worm  wheel  and  the  second  through  a  straight  spur 
gear.  The  pinion  of  the  spur  gear  meshes  with  the 
large  gear  encircling  the  stabilizer  casing,  shown  in 
Fig.  2. 

Ill  order  to  check  the  precession  of  the  gyro  in 
case  of  accident  to  the  precession  gear  when  the  ship  is 
rolling  heavily  a  buffer  is  provided.     This  is  nothing 


FIG.   I — THE  KINGSBURY  AND  THE  BALL  THRUST  BEARINGS 

the  oil  pressure  may  be  relieved  and  the  ball  bearing 
will  still  be  held  in  the  same  position  by  the  nut.  For 
lowering  the  bearing  the  reverse  operation  holds. 

On  the  right  of  Fig.  i,  is  shown  the  gear  type  oil 
pump  driven  from  the  rotor.  This  pump  supplies  suf- 
ficient oil  to  the  system  when  the  rotor  is  spinning  at 
the  normal  speed  of  1500  r.p.m.  but  for  other  speeds 
the  auxiliary  pump  is  required.  The  extension  shaft 
extending  down  through  the  cap  is  for  the  purpose  of 
obtaining  the  speed  of  the  rotor. 

The  whole  gyro  unit,  consisting  of  rotor,  bearing 
motor  and  casing  is  supported  on  gudgeons  or  trun- 
nions cast  and  turned  on  the  center  casing  with  their 
axis  at  right  angles  to  the  axis  of  spin  of  the  rotor.  The 
bearing  itself  consists  of  a  roller  bearing  having  its 
outer  race  turned  spherically.  In  addition  to  serving  as 
a  bearing,  this  gudgeon  also  furnishes  space  for  the 
swivel  joint  through  which  the  lubricating  oil  is  passed 
to  and  from  the  cooler,  strainer  and  auxiliary  oil  pump. 
As    the    case    is    precessing    or    oscillating    about    the 


FIG,   2 — LYNDONIA   STABILIZER  ASSEMBLED  FOR  TEST 

more  than  a  shock  absorber  consisting  of  a  coiled 
spring,  against  which  a  hammer  or  projection  on  the 
center  casing  strikes  as  it  precesses  beyond  a  certain 
set  angle. 

The  entire  casing  and  oiling  system  is  air  tight 
and  operates  under  a  partial  vacuum  of  from  15  to  20 
inches.  With  this  partial  vacuum  there  is  a  saving  of 
about  20  h.p.  A  higher  vacuum  would  be  carried  ex- 
cept for  lubricating  and  motor  difficulty.  The  vacuum 
is  obtained  by  means  of  a  small  air  compressor  with  its 
valves  reversed  and  driven  by  a  1/2  h.p.  motor.  The 
motor  is  controlled  by  a  switch  that  closes  when  the 
vacuum  falls  to  15  inches  and  opens  when  it  reaches 
20  inches.  With  this  arrangement  and  a  reasonably 
tight  system  the  motor  operates  about  five  minutes 
everv  half  hour. 


The  Elect] 


T.  P.  KIRKPATRICK  and  H    C    COLEMAN 

Engineering  Dept., 
W'estinghouse  Electric  &  Mfg.  Company 


THE  rapidly  increasing  use  of  the  gyroscopic  sta- 
bilizer has  led  to  the  development  of  electrical 
apparatus  designed  especially  for  this  service. 
The  principal  operations  of  stabilizing  a  vessel  are  con- 
trolled by  two  motors,  the  spinning  motor  and  the  pre- 
cession motor.  The  spinning  motor,  as  its  name  im- 
plies, keeps  the  rotor  spinning  about  its  axis,  which  is 
normally  vertical.  The  precession  motor,  operating 
through  a  worm  gear,  precesses  the  stabilizer  af  inter- 
vals corresponding  to  those  of  the  waves.  The  com- 
bination of  these  two  rotations,  sets  up  a  gyroscopic 
couple  at  right  angles  to  both  of  them.  This  couple, 
transmitted  through  the  gudgeon  bearings  to  the  .•^hip 
structure,  counteracts  the 
effort  of  the  waves  to  make 
the  ship  roll. 

The    complete    electrical 
equipment    required    by    the 
stabilizer  consists  of  the  fol- 
lowing : — 
I — Control  gjTO, 
2 — Precession  motor, 
3 — Generator  to  supply  power  to 
precession  motor, 

4 — Magnetic  brakes  for  preces- 
sion system, 

5 — Motor  driven  vacuum  pump, 
6 — Control  panels, 
7 — Spinning  motor, 
8 — Generator  to  supply  power  lo 
spinning  motor. 

The  control  gyro,  upon 
which  depends  the  proper 
time  of  application  of  the 
forces  of  the  stabilizer,  car- 
ries a  contact  tip  projecting 
between  two  stationary  con- 
tacts mounted  on  the  base  of  the  unit,  these  con- 
tacts being  spaced  about  one-half  inch  apart.  Control 
circuits  are  led  from  these  contacts  to  the  operating 
coils  of  the  magnetic  contactor  switches  which  control 
the  precession  motor. 

The  precession  motor  of  the  Lyndonia  is  an  8.5 
hp,  115  volt,  720  r.p.m.,  compound  wound  machine  of 
the  standard  industrial  type,  except  for  the  moisture 
proof  impregnation  and  non-corrodible  fittings  for  ma- 
rine use.  As  shown  in  Fig.  i,  the  power  from  this  mo- 
tor is  transmitted  through  a  worm  gear  reduction  unit 
to  the  large  half  gear  on  the  gyro  casing.  The  function 
of  this  motor  is  to  bring  the  g>'ro  to  full  precession 
speed  with  the  least  possible  delay,  after  the  ship  starts 
to  roll  enough  to  operate  the  control  gj'ro.  Upon  its 
ability  to  do  this  depends,  to  a  great  extent,  the  effi- 
ciency or  nearness  of  approach  to  complete  stabiliza- 


tion.    The  rating  given  above  is  based  on  the  r.m.s.  , 
load  over  one  complete  precession  cycle. 

Power  is  supplied  to  the  precession  motor  by  a 
compound  wound,  direct-current  generator  driven  by 
a  steam  turbine,  which  also  drives  an  alternator  for 
supplying  power  to  the  spinning  motor.  The  direct- 
current  generator  furnishes  power  to  the  precession 
motor  only  and  therefore  has  the  same  rating. 

The  main  control  equipment  is  very  simple.  For 
the  precession  motor,  a  cabinet  type  contactor  panel 
is  used.  This  panel  carries  the  contactors  for  starting 
and  reversing,  including  one  accelerating  contactor,  as 
well  as  an  overload  relay,  and  self-contained  starting 
resistances.  This  panel  is 
completely  controlled  by  the 
control  gyro.  In  addition  to 
this,  a  small  switchboard 
panel  is  mounted  at  the  side 
of  the  stabilizer  compart- 
ment, just  above  the  tuibine 
generator  set.  This  panel 
carries  a  carbon  circuit 
breaker  for  the  alternating- 
current  circuit,  necessary- 
meters  and  knife  switches 
for  the  various  feeder  cir- 
cuits, and  the  generator 
field  rheostat. 

The  large  fly  wheel  of 
the  gyroscope,  operating  in 
a  vacuum,  would  run  for 
several  hours  after  the 
power  was  shut  oflf  from  the 
driving  motor,  unless  some  external  means  of  slow- 
ing it  down  was  provided.  This  would,  of  course,  be 
undesirable  at  all  times,  and  especially  so  in  case  any 
bearing  trouble  should  develop.  A  novel  braking  ar- 
rangement has  therefore  been  developed  for  quickly 
stopping  the  fly  wheel,  whenever  this  becomes  desir- 
able. This  arrangement  has  proved  very  effective  in 
service,  permitting  the  fly  wheel  to  be  brought  to  rest 
in  a  small  fraction  of  the  time  that  would  be  required 
if  it  were  allowed  to  run  until  stopped  by  friction  and 
windage  only. 

On  this  installation,  the  g)'ro  rotor  acts  as  a  fly- 
wheel in  balancing  the  load  on  the  turbine.  When  the 
piecession  motor  is  started,  it  throws  a  peak  load  on 
the  turbine,  causing  it  to  slow  down.  As  soon  as  the 
speed  drops  below  the  synchronous  speed  of  the  spin- 
ning motor,  the  latter  operates  as  an  induction  genera- 


ST.\BILIZER   OX   TEST   FLOOR 


August,  192 1 


THE   ELECTRIC.  JOURNAL 


345 


tor,  driven  by  the  gyro  rotor,  thus  assisting  the  turbine 
to  drive  the  direct-current  generator  during  the  over- 
load.    It  will  be  noted  that  the  stabilizer  equipment  is 


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FIG.   2 — PRECESSION   MOTOR  LOAD  AND  SPEED  CURVES 

self-contained  electrically,  with  the  exception  of  the 
small  amount  of  current  required  for  the  control  cir- 
cuit of  the  control  gyro  and  its  motor. 

OPERATION  OF  THE  PRECESSION  SYSTEM 

Curves  of  the  precession  motor  armature  current 
and  speed  plotted  against  time  in  seconds,  based  on  a 
normal  period  of  roll  of  the  vessel  of  ten  seconds  are 
given  in  Fig.  2.  Assume  that  the  ship  begins  to  roll. 
About  one-quarter  second  later,  the  control  gj'ro  closes 
the  control  circuit  to  the  line  contactor,  causing  it  to 
close  and  connect  the  precession  motor  in  series  with 
the  starting  resistance  and 
brake  coils  to  the  power 
supply.  Thus  the  brakes 
are  released  and  the  motor 
starts.  The  motor  must 
accommodate  200  percent 
full  load  current  at  start. 
The  current  rapidly  drops 
to  the  full  load  value  as 
the  motor  speeds  up. 
Then  the  accelerating  con- 
tactor closes,  cutting  out 
the  starting  resistance  and 
the  series  field  of  the  mo- 
tor. This  causes  the  cur- 
rent to  increase  again  to 
about     150     percent     full 

load  and  the  motor  quickly  comes  up  to  speed. 
The  series  field  of  the  motor  is  used  on  the  first  step  to 
give  good  starting  torque  and  is  then  cut  out  in  order 
to  give  better  regulation  during  the  remainder  of  the 
cycle. 

The    g\'ro   has    now    reached    a    precession    speed 
which  it  tends  to  accelerate   further  by  virtue  of  the 


forces  exerted  on  it  by  the  ship.  Thus  the  load  on 
the  precession  motor  rapidly  decreases.  The  brake 
coils  are  designed  to  hold  the  brakes  released,  or  free, 
until  the  precession  motor  current  drops  to  approxi- 
mately 25  percent  full  load.  Then  the  brakes  set, 
throwing  more  load  on  the  precession  motor  and  slow- 
ing it  down.  The  current  then  increases  until  approxi- 
mately 45  percent  full  load  is  reached,  when  the  brakes 
again  release.  Thus  the  precession  speed  is  main- 
tained between  certain  limits  during  the  remainder  of 
the  cycle,  as  long  as  the  control  gvTO  keeps  the  con- 
tacts closed.  Just  before  the  end  of  the  roll,  the  con- 
trol gyro  opens  the  contact,  cutting  the  power  off  the 
motor  and  brakes,  causing  them  to  set  and  rapidly 
bring  the  precession  to  a  stop.  Then  as  the  ship  starts 
to  roll  to  the  other  side,  the  same  operation  takes  place 
in  the  reverse  direction.  This  constitutes  a  complete 
cycle. 

Fig.  3,  shows  sections  of  graphic  meter  charts, 
giving  simultaneous  values  of  precession  motor  cur- 
rent and  speed  taken  during  the  trial  trip  in  January 
of  this  year.  These  were  taken  before  final  adjust- 
ments were  made  in  the  starting  resistance  to  bring  the 
current  peaks  more  nearly  equal.  However,  they  will 
serve  to  show  what  a  widely  varying  load  this  motor 
must  carry. 

THE   SPINNING    MOTOR 

The  spinning  motor  is  the  most  special  part  of  the 
electrical  equipment  and  is  of  interest  both  on  account 
of  its  construction  and  the  duty  it  has  to  perform.  The 
best  design  of  the  stabilizer  required  that  the  spinning 
motor  be  located  on  the  shaft  of  the  rotor  between  the 
flywheel  and  the  lower  guide  bearings.  Therefore  a 
motor  was  required  that  could  operate  continuously  in 


FIG.  3 — GRAPHIC  METER  RECORDS  OF  PRECESSION  MOTOR  CURRENT     AND  SPEED 

a  partial  vacuum  and  also  have  such  proportions  that 
its  rotating  element  could  be  mounted  directly  on  the 
rotor  shaft.  This  motor  was  to  be  able  to  break  away 
and  accelerate  a  22000  lb.  rotor  from  rest  to  full 
speed,  then  spin  the  rotor  continuously  at  1500  r.p.m. 
About  33  hp  is  required  to  spin  the  rotor  at  1500 
r.p.m.  under  partial  vacuum.     This  power  is  required 


346 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


to  overcome  bearing  friction  and  windage  and  drive 
the  small  geared  oil  pump.  It  is  constant  whether  the 
stabilizer  is  precessing  or  not  except  for  a  slight  fluctu- 
ation of  the  friction  losses  due  to  the  pressure  changing 
on  the  bearings  as  the  stabilizer  is  precessed.  On  ac- 
count of  the  momentum  of  the  rotor  this  fluctuation  is 
not  perceptible  on  an  ammeter  in  the  circuit,  but  is  in- 
dicated by  a  slightly  increased  power  consumption. 

If  the  same  motor  is  to  be  used  to  start  and  accel- 
erate the  rotor  that  is  to  be  used  to  spin  it,  something 
must  be  done  to  bring  the  torque  requirements  of  the 
different  parts  of  the  duty  cycle  somewhere  near  the 
same  value.  In  designing  the  stabilizer  every  effort  was 
made  to  make  the  starting,  or  break  away  torque  as  low 
as  possible.  How  successful  these  steps  have  proved 
may  be  judged  from  the  results  of  a  series  of  starting 
tests  on  the  Lyndonia  stabilizer  where  the  22  000  lb. 
rotor  was  started  from  rest  a  number  of  times  by  hand. 
The  average  break  away  torque  obtained  from  these 
tests  was  40  lbs.  at  one  foot  radius.  These  tests  repre- 
sent very  nearly  ideal  conditions  however,  and  the 
spinning  motor  was  designed  to  have  a  starting  torque 
of  80  lbs.  to  care  for  cases  when  the  bearings  are 
worn  or  slightly  rough. 


FIG.  4— CROSS  SECTION  OF  SPINNING  MOTOR 

The  inertia  of  the  rotor  is  so  large  that  it  would 
require  a  prohibitive  torque  to  accelerate  it  to  speed  in 
a  short  time.  By  lengthening  the  time  of  acceleration 
this  torque  can  be  reduced.  If  the  acceleration  period 
should  be  lengthened  until  the  torque  required  was 
equivalent  to  a  50  percent  overload  torque  on  the  mo- 
tor, the  time  of  acceleration  would  be  about  75  mia'utes. 
This  figure  will,  of  course,  varA'  to  some  extent  with 
different  sizes  of  stabilizers. 

There  is  no  serious  objection  to  this  length  of  time 
of  acceleration  on  a  stabilizer,  as  a  rough  sea  can  al- 
ways be  anticipated  long  enough  ahead  to  prepare  for 
it.  Also  it  is  not  necessary  to  have  the  rotor  at  full 
speed  before  starting  to  stabilize.  The  acceleration 
period  is  the  most  difficult  part  of  the  duty  cycle  of 
the  spinning  motor  and  is  the  principal  consideration 
in  the  selection  of  the  motor  to  be  used. 

There  are  several  types  of  motors  that  might  be 
adapted  to  this  service,  among  which  are : — 
I — Direct-current  shunt  motor. 

2 — Wound-rotor  induction  motor  with  external  resist- 
ance. 
3 — Squirrel-cage  induction  motor  using  variable  primary 
frequency  to  get  variable  speed. 

After  considering  these  three  types  carefully  the  squir- 
rel-cage motor  was  selected  as  being  the  most  suitable 


one  for  this  application.  The  simplicity  and  rugged- 
ness  of  the  rotor  is  of  special  advantage  here,  as  the 
heat  from  nearly  all  of  the  rotor  losses  must  be  con- 
ducted away  through  the  shaft.  The  stator  is  natural- 
ly compact  and  can  be  easily  adapted  to  water  cooling. 
The  method  of  starting  with  low  frequency  and  volt- 
age, and  accelerating  by  raising  the  frequency  and  volt- 
age together  gives  the  best  current  and  torque  condi- 
tions in  the  motor  that  can  be  obtained.  Furthermore 
the  squirrel-cage  motor  can  be  designed  to  have  very 
desirable  performance  characteristics  at  both  low  and 
high  frequency. 

The  motor  used  on  the  Lyndonia  is  a  three-phase, 
50  cycle,  four-pole,  1500  r.  p.  m.  vertical  squirrel  cage 
induction  motor,  with  a  frame  arranged  for  water  cool- 
ing. The  frame  is  split  horizontally  to  permit  the 
cooling  coil  to  be  assembled  inside.  At  the  water  port 
the  frame  is  widened  to  permit  a  double  bend  in  the 
ends  of  the  cooling  coil.  Figs.  4  and  5  show  the  frame 
with    the   cooling   coil   in   place.     The   gyro    casing   is 


FIG.   5 — FR.WIF.   WITH    COOLING   COII,   IN    PL.\CE 

drilled  at  a  point  directly  under  the  water  port  in  such 
a  manner  that  the  inlet  and  outlet  pipes  can  be  tapped 
directly  into  the  ends  of  the  cooling  coil  from  outside 
the  stabilizer.  This  construction  removes  all  chance 
of  trouble  from  internal  piping,  and  makes  the  pipe 
fitting  very  simple.  The  cover  fits  over  the  open  top 
of  the  body  and  provides  support  for  the  end  plate  and 
primary  connections.  The  cooling  coil  consists  of 
several  turns  of  one  inch  copper  tubing  arranged  in  a 
double  coil,  inside  the  U  of  the  body.  After  the  coil 
is  in  place,  the  remaining  space  inside  the  frame  is 
filled  with  babbitt  metal,  making  a  solid  metal  path  for 
the  heat  to  flow  from  the  frame  to  the  cooling  water. 
The  primary  core  fits  snugly  into  the  frame,  and  is 
held  in  place  by  a  key  and  bolted  on  end  plates. 

The  primarj'  winding  is  made  up  of  separately 
insulated  copper  straps.  These  conductors  form  a 
double  layer  group  winding,  similar  in  electrical  char- 
acteristics to  the  usual  induction  motor  winding  when 
partially  closed    slots    are    used.     The    end    turns    are, 


August,  192 1 


however,  bent  back  to  lie  as  closely  against  the  end 
plates  as  possible.  To  get  the  coils  still  more  compact 
they  are  made  m  halves  and  joined  at  each  end  bv 
figure  8  connectors  after  they  have  been  placed  in  the 
slot..     The    cross    connections    are    of    strap    and   are 


THE    ELECTRIC  JOURNAL 


347 


FIG.   ^BOITOM   VIEW   OF   SPINNING   MOTOR   STATOR 

nested  on  top  of  the  motor  .just  outside  the  coil  ends 
as  shown  in  Fig.  6. 

The  assembled  stator  is  treated  with  several  coats 
of  an  insulating  varnish  which  fills  the  air  spaces  be- 
ween  the  coils.  This  greatly  improves  the  therm  1 
conductivity  between  the  coil  ends  and  the  endpla^e 
Another  no  less  important  result  of  this  treatment  s 
u^e'S""  °'  ^'^  'T"'^^*°"  ^'•°-  ^'-  -1  -d  mi! 
lons.       As  can  be  seen  from  the  illustrations,  the  sta- 

casinr''.^'''^^^'""  "''  "°*°'"  ^'^  ^'■^"^ht  out  of  the 
casmg    through    a    terminal    port    plate.     Six    copper 
s  uds  insulated  by  micarta  tubes  extend  through T 
P  ate   being  held  in  place   and  the   openings    seald   bv 
s  uffmg  gl     d3  filled  with  packing,  sa'turatS  :^. 

ons  couli  b      ,"'"   r^'^'  °"^  ^°  ^"^^^  ^^^  — - 
the  mZr  ^'^"'^'  "  ^"^  '""^  ^-^^^-^  '^--'bing 

ner  th.  '"^\^°^^'f  ^™'"  ^^e  ends  to  the  imbedded  cop- 
per thence  through  the  insulation,  core,  and  frame  To 
^he  cooling  water,  a  temperature  gradient  of  48  dT;;e 
calcullTT  '"  '"'  '"PP^'-  ^"^  ^he  cooling  tater  I 

h  uiit^her^,""  T'°'^'  '°^^^^  ^'  '^^  -°^-  -^ 
suits  rj  hat  th:r'"  ■^°^''^'^"^^-  '^-^  - 

bly  less  than  thT  *^.  ^'"^^^'^^^  '^  ^^tually  considera- 
dire  t Iv    rn      ..  '  "     ''''"^"  '^^'"^^  P^'"'  °f  th^  heat  went 

c  P  Is  I  v"ar  "'  "'"''"^^  ^°  *^^  ^---  Thermo- 
couples m  various  parts  of  the  motor  show  that  it  is 
-11  withm  the  temperature  limits  at  all  times    Jhe" 


supplied  with  about  30  gallons    of    cooling    water   per 

The  rotor  is  only  slightly  different  from  the  usu  il 
squ,rrel-cage  type.  The  spider  is  a  steel  casting  e 
sembhng  a  bushing  more  than  a  spider,  as  the  shaft  di 
an:eter  is  only  two  inches  less  than  the  inside  tmete 
of  the  punchmgs.  The  laminations  fit  snugly  on  th 
spider  and  are  held    in   place  by   a   key   and   endplate 

elec^triratlr  H^  'T  "^"^^  ^^"^-^'  ^^^  ^^^ 
electrically  brazed  end  rings.     The  upper  end  rine  is 

provided  with  a  number  of  lugs  whichTre  bolttdZh 
spider.  This  serves  to  hold  the  winding  in  place  The 
lower  end  ring  hangs  free,  allowing  fieedom  for  et 
pansion  and  contraction  due  to  temperatuTe  changTs" 
The  complete  spider  is  pressed  on  the  stabilizer  shaft 
and  IS  secured  in  place  by  a  spanner  nut 

The  losses  in  the  rotor  must  be  dissipated  princ' 
I-ally     by     radiation     and     conduction     through      he 

:  Possible  °T^f  "^r"' '''''  -'-  -^^  - '  w 

:oto?;:fneve?:lred':\tt  tf^  '''''-''  '-' '- 

-I VI  ,        '^acnea  a  high  temperature. 

When  the  spinning  motor  is  to  be  a  Mjulrrel-cage 

utd'ThrT"'"' '"  '"'7''"^'  ^^"^'^^  °^  p—  -  e 

qu.ied,  the  frequency  of  which  can  be  varied  at  will 

sZ;';k"'""'°"-     °"  *^  Lyndonia  this  po    e'i 
supplied  by  a  turbine-generator  set.       The  turb  ne 
equipped  with  auxiliary  nozzles  for  speed  contrd      On 
another  installation  where  the    ship's    drive    i     Diesel- 
tt  s   cieTe^  '^  T"^'  ''  '  -tor-generator  set   T 

reltZe      ,  .''m       "    ''"'^    ^^   '    combination    of 
lesistance  and  field  control. 


no    rrr""""    °'  ™'   """^"^   IMPEDANCE  AT  SO  CVCLFS 
FIG.  8-mAGRAM   OP  THE  P81MARV  IMPEDANCE  AT  ONE  cSe 


A  rotary  converter,  operated  inverted,  may  be  used 
where  direct-current  power  is  available.     This   wou  d 

ctr  "I"  T' '  """^  °'  p°-^^  -  -  ^^ 

1^  in  eitnei    case    the   peculiar   requirements    of 

tl-  service  must  be  considered  in  the  design      When 


348 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


starting  the  spinning  motor  the  generator  must  run 
for  a  considerable  time  at  reduced  speed  with  a  heavy 
overload  current.  Where  self-ventilated  machines  are 
used,  this  means  maximum  heat  to  dissipate  when  the 
ventilation  is  poorest.  The  field  and  armature  wind- 
ings must  be  built  to  meet  these  conditions.  The  water 
cooled  spinning  motor  is  free  from  this  difficulty.  If 
the  motor  were  to  overheat  during  the  accelerating 
period  the  supply  of  cooling  water  could  be  increased 
to  correct  the  trouble. 

In  case  of  a  rotary  converter  operating  from  a 
125  volt  direct-current  ship  circuit  the  highest  alter- 
nating voltage  will  be  78  volts,  three-phase  or  90  volts, 
six-phase.  With  these  voltages  at  full  frequency  tKe 
voltage  at  low  frequency  becomes  very  low.  The 
brush  contact  resistance  and  the  drop  through  the  leads 
are  quite  important  factors  under  these  conditions  and 
their  effect  on  the  performance  of  the  set  must  be 


H500 

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»    3S0    -.60    4So    560    556 — 

FIG.  9 — SPEED  TORQUE  CURTCS  OF  35  HP  SPINNING  MOTOR 

taken  into  account.  If  a  rotary  converter  is  to  be 
used  for  this  application,  it  should  be  operated  six- 
phase  to  take  advantage  of  the  higher  voltage  ratio 
and  reduced  heating  inherent  to  six-phase  operation. 
Six-phase  operation  makes  no  difference  in  the  per- 
formance of  an  induction  motor. 

The  performance  of  the  spinning  motor  at  verj' 
low  frequencies  offers  an  interesting  subject  for 
analysis.  It  is  commonly  assumed  that  the  torque  of 
an  induction  motor  can  be  kept  constant  for  different 
frequencies  by  keeping  the  voltage  and  frequency  pro- 
portional, thus  maintaining  a  constant  induction  in  the 
iron.  This  is  practically  true  over  a  wide  range  of 
frequencies,  in  motors  of  normal  design.  For  example, 
a  50  cycle,  500  volt  motor  having  a  maximum  torque 
of  500  pounds  would  have  a  maxmium  torque  of  about 
490  lbs.  when  operated  at  25  cycles,  250  volts.  This 
slight  dift'erence  is  due  to  the  primary  resistance, 
which  is  constant,  being  a  larger  percentage  of  250 
volts  than  of  500  volts.     This  resistance  drop  is  usually 


such  a  small  percentage  of  the  impressed  voltage  that 
in  ordinary  practice  it  may  be  neglected. 

When  motors  are  to  be  operated  at  extremely  low 
frequencies  this  resistance  drop  becomes  an  increas- 
ingly large  part  of  the  primary  impedance  and  must 
be  considered.     This  may  be  readily  seen  by  compar- 


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FIG.    10 — TORQUE   AND   CURRENT    CURVES   OF   SPINNING    MOTOR   AT    I, 
5  AND  50  CYCLES 

Voltage  being  proportional  to  frequency. 

ing  the  vector  diagrams  of  a  motor  at  50  cycles,  Fig. 
7  and  the  same  motor  at  one  cycle,  Fig.  8.  In  Fig.  8 
the  scale  for  the  voltage  vectors  has  been  multiplied 
by  50  to  show  the  relative  values  of  the  different  vec- 
tors more  clearly.  In  the  50  cycle  diagram  the  prim- 
ary /j/?i  drop  vector  is  almost  negligible.  If  this  dia- 
gram were  redrawn  for  25  cycles,  this  vector  would 
be  just  twice  the  length  it  is  in  the  50  cycle  diagram 
and  the  effect  would  still  be  very  small. 


-400 

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« 

FIG.   1 1 — PULL-OUT  AND  STARTING  TORQUE  CURVES 

35  hp  spinning  motor  driven  by  31  kv-a  alternating-current 
generator. 

The  primary  reactance  drop  /^-Yj  which  is  nor- 
mally five  to  ten  times  the  resistance  drop  and  conse- 
quently is  the  controlling  factor  in  the  impedance,  is 
not  affected  in  this  manner  by  the  change  in  frequency. 
The  reactance,  being  directly  proportional  to  the  fre- 


August,   1921 


THE    ELECTRIC   JOURNAL 


quency,  varies  with  the  voltage,  the  percent  reactance 
remaining  a  constant.  It  will  be  noted  in  comparing 
Figs.  7  and  8,  that  the  effective  voltage  for  inducing 
power  into  the  secondary  is  a  much  smaller  part  of 
the  impressed  voltage  at  one  cycle  than  at  50  cycles, 
also  that  the  power- factor,  which  is  the  cosine  of  the 
angle  B,  is  much  better  at  one' cycle  than  at  50. 

The  effect  of  the  resistance  drop  on  the  maxmium 
torque  can  be  seen  in  Fig.  9.  The  maximum  torque 
decreases  slowly  between  50  and  10  cycles,  then  rapidly 
between  10  cycles  and  zero. 

Another  interesting  change  occurs  in  the  charac- 
teristics of  the  motor  with  variable  frequency.  At  50 
cycles  the  slip  at  full  load  and  the  starting  torque  are 
both  small.  The  secondary  resistance,  being  a  constant, 
becomes  an  increasing  percentage  with  decreasing  fre- 
quency, and  the  percent  slip  and  starting  torque  are 
increased. 

This  is  a  very  important  advantage  of  this  method 
of  starting  squirrel-cage  motors.  Ordinarily  the  sec- 
ondary resistance  is  made  large  enough  to  get  the  nec- 
essary starting  torque  with  full  frequency  applied. 
When  starting  with  very  low  frequency  the  motor 
can  be  so  proportioned  that  the  maximum  torque  will 
occur  at  starting  and  yet  when  it  is  up  to  full  speed 
the  characteristics  will  have  changed  so  that  the  slip 
will  be  about  half  that  of  the  usual  motor,  and  the 
efficiency  correspondingly  higher.  This  is  shown 
clearly  in  the  speed  torque  curves  of  the  same  motor 


349 

at  so  cycles  and  at  one  cycle.  Fig.  10 ;  here  the  one  cycle 
curve  is  repeated  in  dotted  lines  to  a  larger  scale  for 
clearness.  It  will  be  noted  that  the  maximum  torques 
decrease  to  values  even  less  than  the  full  load  torque 
at  low  frequencies.  If  it  is  necessary  to  have  more 
torque  at  these  very  low  frequencies  the  impressed 
voltage  may  be  increased  considerably  without  damage 
to  the  motor,  as  the  core  losses  are  small.  Fig.  9 
shows  the  curve  at  5  cycles  with  the  voltage  increased 
to  give  the  same  torque  obtained  at  50  cycles. 

In  analyzing  the  performance  at  low  frequencies 
It  was  found  that  with  a  particular  spinning  motor  and 
Its  generator  there  was  a  very  definite  frequency 
where  maximum  starting  torque  could  be  obtained 
from  the  set.  This  frequency  was  approximately  five 
cycles  for  the  Lyndonia  equipment.  Above  five  cycles 
the  starting  torque  begins  to  decrease  due  to  the  chang- 
ing characteristics  of  the  motor.  Also  the  higher 
starting  currents  required  by  the  motor  at  higher  fre- 
quencies cause  the  generator  voltage  to  be  lowered. 
Fig.  II  shows  the  variation  of  pull  out  and  starting  tor- 
que of  the  set  at  different  frequencies. 

In  cases  where  an  individual  generator  is  avail- 
able this  method  of  starting,  and  controlling  the  speed 
with  variable  frequency  is  very  desirable.  It  is 
simple,  flexible,  and  efficient.  It  gives  practically  con- 
stant torque  over  a  wide  range  of  speeds  with  very 
nearlv  constant  current. 


"l^oai:  Noto  :iV(otlu)ci 

p.  THOMAS 

Westinghouse  Research  Laborator>- 


THE  capacities  of  several  pin  type  suspension  in- 
sulators, and  the  capacities  to  ground  of  vari- 
ous numbers  of  the  same  insulators  in  series  are 
exceedingly  small.  Rough  measurements  at  low  fre- 
quency by  a  bridge  method  show  that  they  are  of  the 
order  of  0.000025  microfarad.  This  value  of  capacity 
is  about  that  of  one  millimeter  on  the  scale  of  an 
ordinary  variable  air  condenser,  and  it  was  desired  that 
the  results  be  accurate  within  five  percent.  It  is  ap- 
parent, then,  that  to  reach  this  precision  called  for 
special  methods,  or  apparatus,  or  both.  No  low  fre- 
quency apparatus  having  sufficient  sensitivity  for  this 
work  was  available.  It  was  felt,  also,  that  due  to 
parallel  leakage  and  absorption,  results  by  any  direct- 
current  method  would  be  open  to  considerable  question. 
A  calculation  showed  that  at  a  moderate  radio  fre- 
quency, the  addition  of  one  of  these  units  in  parallel 
with  the  oscillating  circuit  condenser,  would  alter  the 
frequency  by  an  amount  corresponding  to  an  audible 
tone.  I.e.  the  ordinary  "beat  receiver",  with  suitable 
modifications,  could  be  employed.  The  first  idea  tried 
was  to  tune  two  oscillating  circuits  to  exact  resonance, 


displace  one  of  them  by  the  addition  of  the  unknown 
condenser,  and  restore  synchronism  by  decreasing  the 
capacity  of  the  main  oscillating  condenser  which  had 
been  paralleled  by  the  unknown.  The  necessary  de- 
crease was  found  to  be  so  small,  however,  as  to  require 
the  calibration  of  special  vernier  air  condensers. 

It  then  occurred  to  us  that  something  might  be 
done  by  measuring  the  frequency  of  the  beat  note  pro- 
duced. This  idea  was  worked  out  on  paper,  tried  out 
roughly  and  finally  adopted  in  the  following  form. 
Two  oscillators  were  set  up,  one  driven  by  a  fifty  watt 
transmitting  tube,  the  other  a  standard  regenerative  de- 
tector-amplifier circuit  with  a  loud  speaking  receiver. 
This  receiver  was  found  necessary,  because  of  circuit 
capacity  changes  caused  by  use  of  head  phones.  In 
making  a  test,  the  two  circuits  were  adjusted  to  give  a 
beat  note  of  a  frequency  suited  to  measurement  by  a 
second  resonance  with  the  note  from  an  air  siren, 
driven  by  a  variable  speed  direct-current  motor  pro- 
vided with  a  carefully  calibrated  tachometer.  The  un- 
known capacity  was  then  added  in  parallel  with  the 
variable  condenser  in  the  detector  circuit,   thus  caus- 


35° 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


ing  a  shift  in  the  beat  note  frequency  to  a  new  value. 
The  unknown  capacity  was  then  replaced  by  a  small 
standard  fixed  condenser  of  accurately  known  ca- 
pacity, and  the  frequency  of  this  third  beat  note  was 
measured  in  the  same  way.  The  unknown  capacity 
could  then  be  calculated  from  the  known  capacity  and 
the  three  beat  note  frequencies,  by  direct  ratio.  The 
equations  for  the  calculations  were  derived  as  follows: 
The  fundamental  frequency  is 

(  ) 


2^\    L    C 
The  frequency  with  c  added,  is 

F-  f  = 


Squaring,    eliminating   C   and    cancelling   common 
terms, 

^ir'  Lc  =     JTs.  '..'"> 

Neglecting  terms  involving  /  and  /-,  as  compared 


to  F, 


K^  Lc  = 


?f 


(J/') 


Or,  expressing  the  fundamental  wave  in  meters, 
/.SS  X  /o-'  A'/ 


.(-•) 


A  similar  equation  holds  when  the  unknown  ca- 
pacity, c,  is  replaced  by  a  second  capacity  c^.  Hence 
we  have  at  once, 

_r f_ 

717=  /„ 
In  these  equations,  the  frequencies  /  and  /„  are  the  dif- 
ferences in  beat  note  pitch  between  the  beat  note  with 
neither  c  nor  Co  connected,  and  the  pitch  with  (i)  c 
and  (2)  Co  connected.  The  quantity  X  represents  the 
fundamental  wave  length,  in  meters,  of  the  primary 
oscillating  circuit;  this  is  supposed  to  remain  constant, 
and  when  a  substitution  method  is  used,  the  value  of  X 
does  not  enter  the  calculations.  L  is  the  inductance  of 
the  primary  oscillating  circuit. 

In  practical  use  of  this  method,  two  wavemeters 
are  employed,  one  coupled  to  the  primary  oscillator, 
the  other  to  the  detector  circuit.  In  this  way  it  is 
made  certain  that  the  coupling  between  the  two  cir- 
cuits is  not  close  enough  to  introduce  tuning  waves  of 
harmful  strength.  Fairly  accurate  measurements,  in 
the  absence  of  a  fixed  standard  capacity,  can  be  made 
by  use  of  equation  (3),  since  the  primary  inductance 
L  is  subject  to  exact  calculation  (single  layer  coil). 
The  fundamental  frequency  F  or  wave  length  X,  how- 
ever, is  not  exactly  calculable  by  equation  (i),  so  that 
for  very  exact  work,  the  substitution  method  and  equa- 
tion (4)  is  more  reliable.  The  method  is  beautifully 
simple  and  easy  to  operate,  besides  being  extremely 
sensitive. 

Table  I  gives  the  data  and  calculation  for  one  test 
run  on  seven  pin  type  suspension  insulators,  by  the 
substitution  method.  The  known  condenser  had  a  ca- 
pacity  of  0.0000828   microfarads.     The   circuits   were 


tuned  to  a  fundamental  wave  length  of  1400  meters. 
The  siren  used  had  thirty  holes,  so  that  the  r.p.m.  as 
read  on  the  tachometer  was  twice  the  frequency. 

Note  the  value  calculated  by  equation  (3)  for  the 
standard,  0.0000790,  as  compared  with  its  known 
value  of  0.0000828.     The  values  given  in  Table  I,  for 

TABLE  I— CAPACITY  OF  INDIVIDUAL  INSULATORS. 


Insulator 

Beat  Note 

Rdgs. 

Number 

On      1     Off 

Diff. 

Capacity,  mfds. 

I 

680 

325 

355 

0.0000244 

2 

700 

350 

350 

0.0000241 

3 

1085 

740 

345 

0.0000237 

4 

1085 

740 

345 

0.0000237 

5 

1090 

715 

375 

0.0000258 

6 

1055 

710 

345 

0.0000237 

7 

1020 

67s 

345 

0.0000237 

Standard 

1805 

_655_ 

1150 

0.0000790 

the  insulator  capacities,  were  obtained  by  use  of  equa- 
tion  (4),  taking  the  value  for  <:„  as  0.0000828. 

Table  II  gives  the  capacities  as  determined  for 
strings  with  various  numbers  in  series ;  the  theoretical 
series  value,  in  the  absence  of  distortion,  is  also  given. 

The  departure  from  no-distortion  values  is  shown 
strikingly  by  the  values  for  six  and  seven  string;  the 
increase  was  due  to  the  gradual  approach  of  the  lower 
end  of  the  string  to  ground,  as  more  insulators  were 
'^dded  at  the  lower  end.  The  upper  insulator.  No.  i, 
was  kept  at  a  constant  height  above  ground,  the  string 
being  lengthened  at  the  lower  end. 

Considerable  trouble  was  encountered  with  slow 
changes  in  frequency  of  the  power  circuit.  The  only 
satisfactory  way  to  overcome  this  was  found  to  be  the 
use  of  closely  similar  tubes  for  both  oscillator  and  de- 
tector circuits,  with  common  plate  voltage  and  fila- 
ment current  batteries.  This  shifting  of  the  funda- 
mental wave,  when  present  in  any  degree,  cf  course 
makes  it  difficult  to  get  reliable  readings;  aside  from 
this,  however,  no  difficulties  were  encountered. 

It  can  readily  be  seen  that  the  limit  of  sensitivity 
of  this  method  of  capacity  measurement  has  not  by 
any  means  been  reached  in  the  work  here  described. 

TABLE  II— CAPACITIES  OF  VARIOUS  NUMBERS 
OF  INSULATORS  IN  A  STRING 


Insulators 
in  String 

Measured 
Capacity 

Calculated 

Capacity 

No  Distortion 

I  &  2 

I.  2  &  3 

I,  2,  3  &  4 

I,  2,  3.  4,  &  5 

I,  2,  3,  4.  5.  &  6 

I,  2,  3,  4,  5.  6,  &  7     1 

0.0000158 
0.0000112 
0.0000093 
0.0000072 
0.0000082 
0.0000081 

O.0000121 
0.0000080 
0.0000060 
0.0000049 
0.0000040 
0.0000035 

By  the  use  of  longer  fundamental  wave  lengths,  or 
larger  oscillating  condensers,  or  both,  the  differential 
tone  may  be  kept  around  500  to  1000  cycles  when  the 
unknown  capacity  is  very  much  smaller  than  the  values 
in  these  tests.  The  writer  believes  that  it  will  be  hard 
to  find  an  alternating-current  method  of  capacity 
measurement  which  will  handle  such  small  capacities, 
with  such  a  high  degree  of  accuracy  and  at  the  same 
time  such  marked  ease  of  manipulation,  as  afforded  by 
the  method  just  described. 


Methods  of 


THOMAS  SPOONER 


WHEN  Dr.  Burrows  devised  his  permeameter 
(1909),  it  gave  substantially  correct  results 
for  all  ferromagnetic  materials  then  avail- 
able. This  method  of  test  was  therefore  adopted  by 
the  A.  S.  T.  M.  a  little  later  as  the  standard  method 
for  determining  normal  induction  data.  Since  then, 
however,  ferromagnetic  materials  have  been  developed 
with  maximum  permeabilities  of  several  times  those 
known  in  1909. 

ACCURACY 

Some  years  ago,  Mr.  T.  D.  Yensen  reported  maxi- 
mum permeability  values  of  the  order  of  70  000  for 
special  iron  silicon  alloys  prepared  in  a  vacuum". 
These  samples  were  in  the  form  of  rods  and  were 
tested  by  means  of  the  Burrows  permeameter.  The 
maximum  permeability  values  reported  for  ring  sam- 
ples prepared  by  him  were  about  40000.  Since  then, 
we  have  found  similar  differences  in  material  pre- 
pared at  the  Research  Laboratory.  Moreover,  hy- 
steresis loops  at  a  maximum  induction  of  ten  kilo- 
gausses  indicated  that  the  Burrows  apparatus  gave  re- 
sults   which    were  lower   than   those  obtained  by    the 


CI 


SiJ 


Dimensioi 
Magnet 
0.793       0638 
IJ70       0949 
2856       2.225 


Silicon  Magnet 

0.706  0.635 

20.600  38-200 

1032  0.799 


FIG.    10 — STANDARD  MAGNETIC  UNK 

nng  test.  These  comparisons  were  not  conclusive, 
however,  as  it  is  impossible  to  make  two  samples  of 
different  form  having  the  same  magnetic  properties, 
at  least  when  the  magnetic  quality  is  especially  good.' 
It  was  a  very  desirable,  in  order  to  evaluate  data  ob- 
tained with  the  Burrows  apparatus  to  have  some  ab- 
solute method  of  checking  the  accuracy  of  this  type  of 
permeameter. 

The  Fahy  Simplex  Permeameter,  described  previ- 
ously, is  used  for  tests  on  permanent  magnet  steel,  due 
to  the  simplicity  and  reproducibility  of  results.  We 
were  therefore  anxious  to  know  its  absolute  accuracy, 
also,  in  order  to  compare  our  data  with  those  obtained 
by  other  observers  using  other  methods. 

Check  Methods— Th^TG  are  two  simple,  well 
laiown  methods  of  determining  the  absolute  magnetic 
characteristics  of  a  ferro-magnetic  material  :- 

.r,A  J^/'j^?™,?-'^-'"  '^^  ^l^^Ps  of  an  ellipsoid  or  a  very  lone 

2— Ring  sample  tested  ballistically. 
The  first  method  has  been  used  for  checking  per- 
meameters  by  first  preparing  an  ellipsoid,  testing  it  and 
then  machmmg  it  to  a  cylindrical  bar  and  using  it  in 


the  permeameter  to  be  checked.  This  method  has  two 
disadvantages:  first,  an  ellipsoid  is  a  difficult  shape  to 
machine;  and  second,  the  further  machining  may  in- 
troduce mechanical  strains  which  may  alter  the  charac- 
ter of  the  material.  Even  if  the  sample  is  subsequent- 
ly annealed,  it  cannot  be  certain  that  the  annealing  has 
not  altered  the  magnetic  quality.  In  fact,  it  is  proba- 
ble that  it  would  in  most  cases. 

A  more  satisfactory  method  for  checking  permea- 
meters  is  to  use  an  elongated  ring  sample  or  link  Fig 
10,  which  may  be  tested  either  like  a  ring  or  as  a  bar. 
If  such  a  sample  is  wound  with  a  uniform  magnetizing 
winding  coveri.-sr  the  whole  length  and  is  supplied  with 


■ 

— 

— 

__, 

9 1 

- 

- 

:^ 

-— 

^'^ 

■"" 

_ 

'^ 

- 

1 — 1 

^ 

■^ 

~ 

— 

r 

__ 

— 

A 

-rt^ 

■        " 

— 

H 

10 

— 

^ 

X 

~~ 

3 

4-10 

__ 

Z- 

^ 

M 

_ 

'Z 

^ 

^ 

' 

:^ 

d\ 

Lin 

urrov 

^ 

^H 

~ 

— 

__ 

/ 

^ 

/ 

H 

hy 

"~ 

~~ 

6 

- 

/ 

■/ 

y 

y 

^ 

/ 

#■ 

/ 

~ 

J 

/ 

~ 

■> 

Y 

~ 

^. 

~" 

~ 

^ 

^ 

V 

~ 

\           1 







__ 

J'    1    t    1 

H.qaberlf  per  |cM  | 

i 

__ 

±:± 

FIG.    11— NORMAL   INDUCTION    CURVES,    SILICON    STEEL   LINKS 
SAMPLE  A  ' 

Test 

Ring ■.■.■.■.■.".■.■.■■.■.■. ".^ 

Burrows i^ 

a  suitable  secondary  winding,  it  may  be  tested  ballis- 
tically like  a  ring  and  the  results  should  be  correct 
except  for  a  slight  error  at  the  ends,  such  as  would  be 
obtained  with  a  ring  sample  in  which  the  diameter  is 
small  with  reference  to  the  radial  width.  After  testing 
as  a  ring,  if  the  windings  are  removed  the  sample  niay 
then  be  placed  in  a  permeameter  and  tested  as  a  bar. 

A  number  of  such  samples  of  varied  magnetic 
qualities  heve  been  prepared  and  tested  in  a  Burrows 
permeameter  and  a  Fahy  simplex. 


352 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  8 


Test  Samples — Tests  are  reported  on  link  samples 
as  shown  in  Table  III  with  dimensions  as  given  by  Fig. 

TABLE  III— TESTS  ON  LINK  SAMPLES 


Sample                       Material 

Max.  n 

1 

A                 4%   Silicon                       4060 
E                 4%   Silicon                      10900 
Z                 4%   Silicon                      16700 
G                 4%   Silicon                  non-uniform 
2027                     Cr.    mag.                              164 

The  silicon  steel  samples  were  machined  from 
standard  sheet  bars  and  heat  treated  by  Mr.  Yensen  in 
an  electric  furnace.  The  magnet  steel  sample  was  ma- 
chined from  a  standard  chromium  magnet  steel  bar 
and  heated  and  quenched  in  the  usual  way  before  test- 


piG.    12 — HYSTERESIS   LOOPS,   SILICON    STEEL  LINK,   S.VMPLE  A 

ing.  For  use  in  the  Burrows  apparatus  a  similar  link 
of  each  kind  was  provided  in  order  that  the  two  legs 
of  the  apparatus  might  be  approximately  balanced. 

It  was  noted  in  the  earlier  stages  of  the  investiga- 
tion that  some  of  the  higher  permeability  samples 
were  not  uniform  magnetically.  In  order  to  test  the 
uniformity,    we    therefore,    wound    exploring   coils  on 


^  —  '^7 

^'^  ^   '    y'^ 

^                                 ^^        '        ^^ 

J»-     -         Z-^''         /   ' 

1  Li—       4.y        u^' 

?^     .i^  ^^;.' 

i     ^^         Z^ 

"6-2                      I-r 

i^         ^  " 

»          7^ 

•-^         -.t^ 

-^^         7"^ 

rf-         tl 

'4     y-            1- 

"t                   tl 

"14    1 

ZL    t       ^      J 

t    t              t 

-i-         4- 

I.GLlberts  pe^  C  VI. 

FIG.    13 — COMPARISON  OF  FAHY  TESTS,  SILICON  STEEL  LINK, 
SAMPLE  A 

various  portions  of  the  links  and  tested  ballistically  to 
see  if  the  various  coils  when  connected  differentially 
gave    appreciable    deflections.      All    samples    reported 


here,  except  the  G  sample,  were  found  to  De  practically 
uniform.  The  lack  of  uniformity  of  the  earlier  sam- 
ples was  found  to  be  due  to  the  fact  that  the  lieat 
treating  furnace  was  not  uniform  in  temperature 
throughout  its  length.  This  was  corrected  in  treating 
the  later  samples. 

Permeaineters — The  ring  tests  were  made  by 
means  of  the  apparatus  previously  described^^.  The 
Burrows  penneameter  was  designed  and  built  by  the 
Westinghouse  Company  and  was  arranged  for  use  witlf 
sheet  and  bar  material.  By  reference  to  Fig.  9,  it 
will  be  seen  that  the  flux  passes  into  and  out  of  the 
sheets  or  bars  through  the  edges  of  the  sample.  This 
magnetic  circuit  was  especially  well  adapted  for  use 
with  the  link  samples.     It  will  be  noted  that  the  yokes 


— 

r-=* 

==:= 

^^ 

^ 

^ 

==*- 

^ 

^ 

J. 

^ 

1 

f 

, 

r' 
« „ 

' 

^ 

Burr 

"% 

^ 

^ 

10      1 

y 

/ 
^ 

^ 

~Rir 

t       . 

^ 

Fal 

y 

/ 

/ 

y 

^ 

^ 

i ' 

/ 

/ 

y 

^ 

/ 

/ 

/ 

I  , 

/ — 

/ 

/ 

/ 

/ 

r 

/ 

/ 

/ 

- 

J 

•^ 

— I 

' 

' 

i.oa 

,J 

i    "1     . 

per  CM. 

L 

T 

T 

FIG.  14— XOR.MAL  INDUCTION  CURVES,  SILICON  STEEL  LINK  SAMPLE  £ 
Test W  M" 

Ring 10900 

Burrows   17500 

Fahy 73io 

are  laminated  and  made  of  high-permeability,  low- 
hysteresis-loss  material,  thus  reducing  magnetic  visco- 
sity effects  and  eft'ects  due  to  the  retentivity  of  the 
yokes.  The  Fahy  penneameter  was  of  the  simplex 
type.  In  most  cases  the  operation  was  according  to 
the  method  given  in  the  instructions  which  accom- 
panied the  apparatus. 

Test  Results — Figs.  11  to  20  show  the  test  data 
obtained  on  these  link  samples.  For  all  three  methods 
of  test  each  point  on  the  hysteresis  loops  was  obtained 
independently  of  the  others  by  reference  to  the  tip 
value.  AB  was  measured  by  introducing  resistance 
into  the  magnetic  circuit  with  or  without  reversing  the 
magnetizing  current  and  B  was  found  by  subtracting 


August,  1 92 1 


THE   ELECTRIC   JOURNAL 


353 


A5  from  the  tip  value.  For  the  ring  and  Burrows  ap- 
paratus, H  was  measured  by  suitable  accurately  cali- 
brated ammeters. 

For  the  Fahy  permeater,  two  methods  were  used 
in  obtaining  H.  The  standard  method  consists  in 
measuring  H  by  means  of  the  galvanometer  deflection 
when  the  resistance  in  the  magnetizing  circuit  is  in- 
creased to  infinity.  This  assumes  that  there  is  no  re- 
sidual magnetism  in  the  yokes.  We  also  tried  the 
method  of  measuring  A//  when  the  magnetizing  cur- 
rent was  reduced  from  the  maximum  value  and  sub- 
tracting this  AH  from  the  tip  value.  A  comparison 
of  these  two  methods  is  given  by  Fig.  13,  where  the 
full  line  loop  is  reproduced  from  Fig.  12  and  repre- 
sents the  data  as  obtained  by  the  standard  method. 
The  two  values  of  Br  as  shown  by  the  circles  were 
read,  depending  on  whether  zero  H  was  obtained  by 
reducing  the  magnetizing  current  to  zero  in  two  steps 
or  in  one,  the  lower  value  of  B  being  obtained  when 
using   the    former   method.     It  will    be   noted  that  the 


^^ 



::2 

-^ 

7^ 

-^ 

-K- 

^ 

^ 

-^ 

^ 

oi 

,  ^ 

y 

^ 

/ 

/ 

^ 

^ 

-R» 

>g 

/ 

y 

/ 

y 

/ 

/* 

^ 

// 

"/ 

/ 

/ 

/ 

/ 

/ 

/ 

// 

1 

i 

■ 

6 

3     0 

J     u 

' 

... 

\    6.3    0 

1 

5     54     OS      K«     0:7     0 

8       0  9       ro       11       i\l       ill         \ 

Mill 

FIG.    IS — HYSTERESIS   LOOPS,   SILICON   STEEL  LINK,   SAMPLE  E 

corresponding  dots.  Fig.  13,  represent  the  same  points 
when  A//  is  measured  from  the  tip. 

The  data  of  Fig.  20  were  obtained  on  a  very  non- 
uniform link,  the  material  having  high  permeability  at 
the  center  and  low  at  the  ends.  Primary  and  second- 
ary coils  were  arranged  as  shown  by  the  sketches. 
Coils  2  and  j  had  half  the  number  of  turns  of  coils  i. 
Coils  2  were  spaced  about  half  way  between  the  cen- 
ter and  ends  of  the  sample.  The  primary  coils  were 
uniformly  wound,  the  magnetizing  coils  P  occupying 
about  20  cm.  length  of  the  sample  and  the  compensat- 
ing coils  C  about  10  cm.  on  each  end.  There  was  al- 
so a  uniform  secondary  winding  not  shown,  extending 
the  whole  length  of  the  sample.  These  windings  were 
connected  to  a  Burrows  permeameter  table  and  a  Bur- 
rows test  made  in  the  usual  way,  using  first,  coils  /  and 
2,  then  coils  i  and  j.  Since  coils  5  together  had  only 
one-half  the  turns  of  coils  i  together,  coils  j  in  series 
were  bucked  against  one  of  the  coils  /  for  the  compen- 
sating adjustment.  This  should  introduce  no  error, 
however,  since  both  sides  of  the  links  were  identical  at 
the  center.  It  will  be  noted  that  this  arrangement  is 
the  equivalent  of  a  Burrows  permeater  in  which  the 
yokes  are  a  part  of  the  material. 


A  Burrows  test  with  the  regular  Burrows  yoke 
was  also  made  on  this  sample  and  likewise  a  ring  test 
using  the  distributed  secondary  winding. 

RESULTS 

Fig.  II  for  the  5000-maximum  permeability  mater- 
ial shows  a  very  fair  agreement  between  the  ring  and 
Burrows  tests,  with  the  Burrows  slightly  low  in  H  at 
moderate  inductions  and  checking  at  the  higher  values. 
The  Fahy  shows  a  nearly  constant  percentage  of  error 
in  H  at  all  inductions,  the  H  values  being  about  ten  per- 
cent high.  The  hysteresis  losses  (at  Bma^=io  kilo- 
gausses)  for  the  various  methods  of  test  as  shown  by 
Fig.  12  are  about  the  same  but  the  Fahy  gives  a  low 
value  of  5r.     As  shown  by  Fig.  13  for  the  Fahy  results 


J^ 

^ 

-^ 

— 

=3? 

-^ 

^ 

::^ 

i^ 

^ 

/ 

^^ 



^~" 

, 

Bun 

ows__ 

!^ 

:^ 

^ 

•^ 

H 

i 

^ 

^ 

/^ 

-Rin 

'  ^ 

', 

/ 

/ 

^ 

^Fat 

y 

/ 

/ 

/ 

1 

/ 

/ 

/ 

1 

7 

i 

/ 

\ 

/ 

\ 

/ 

\ 

— 

P 

\ 

) 

100 
H.G 

1< 

tberts 

per 

1   5 

1 

"J 

2  0 

FIG.  l6 — NORMAL  INDUCTION  CURVES,  SILICON  STEEL  LINK  SAMPLE  Z 
^  6St p^  Max 

Ring 16700 

Burrows  28200 

Fahy iiooo 

the  standard  method  as  recommended  by  the  manufac- 
turer gives  better  results  for  the  hysteresis  loop  than 
method  2.  The  Fahy  simplex  in  its  present  form  is  not 
suitable  for  obtaining  hysteresis  data  on  high-maxi- 
mum permeability,  low-loss  material,  since  the  H  read- 
ings are  too  small  to  read  accurately  and  the  results  are 
erratic.  It  should  be  noted  that  the  circle  points  of  Fig. 
13  do  not  give  a  smootli  curve.  It  was  impossible  lo 
obtain  any  kind  of  reasonable  hysteresis  data  for  the 
1 1  000  maximum  permeability  material  with  the  Fahy 
simplex. 

Fig.  14  for  the  1 1  000-maximum-permeability  ma- 
terial shows  the  same  effects  as  for  the  5000  permea- 
bility material,  except  that  the  differences  are  exagger- 
ated.    The   maximum   permeability  for   the   Burrows 


354 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  8 


apparatus  is  60  percent  high  and  for  the  Fahy  33  per- 
cent low.  At  inductions  above  14  kilogausses,  the 
Burrows  and  ring  tests  check,  with  the  Fahy  running 
slightly  high  in  H. 


-^ 

^ 

X^ 

' 

y 

t' 

/ 

/ 

/ 

y 

/ 

^ 

-RinH 

// 

? 

/ 

J 

TOWS 

/ 

/ 

1 

' 

& 

a 

I 

0'2 
1 

1     ft     0 

1          1      H. 

I  0:2  0:3  0 

Gilberts  per    CN 

4       0 

5      0 

6      0 

'_ 

FIG.    17 — HYSTERESIS   LOOPS,   SILICON   STEEL   LINKi    SAMPLE  Z 

There  is  a  considerable  error  for  all  constants  of 
the  hysteresis  loop  (see  Fig.  15)  between  the  Bur- 
rows and  ring  tests.  The  Burrows  give  a  high  B^,  low 
//e  and  low  hysteresis  loss,  which  is  in  line  with  our  ex- 
pectations from  previous  data. 

The  permanent  magnetic  steel  sample  (Fig.  18) 
gives  very  good  checks  at  all  inductions,  with  the  Fahy 
running  slightly  low  in  B  at  high  inductions.  The 
hysteresis  constants  (Fig.  19)  are  practically  identical 
for  the  ring  and  Burrows  test,  both  for  loops  having 


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the  sample  and  too  low  for  the  ends.  All  the  other 
tests  probably  give  values  of  H  which  are  too  low  even 
for  the  center  of  the  sample.  It  is  apparent  that  if 
the  permeability  at  the  location  of  coils  2,  is  less  than 
at  the  center,  (the  location  of  coils  j)  more  current 
will  have  to  be  passed  through  the  compensating  coils 
C  in  order  to  give  the  same  flux  through  coils  /  and  2 
than  would  be  the  case  if  the  material  were  uniform. 
That  these  fluxes  must  be  equal  is  the  condition  of 
balance  for  the  Burrows  test.  It  is  obvious  that  if  the 
sample  is  sufficiently  non-uniform  and  the  exploring 
coils  are  wound  close  to  the  sample,  a  condition  would 
be  reached  where  an  apparent  permeability  of  infinity 
would  be  indicated.  In  fact,  we  have  nearly  reached 
this  condition  in  this  case,  where  we  have  an  observed 
maximum  permeability  of  125  000  where  the  material 
probably  has  a  maximum  permeability  at  the  center  of 
about  15000.  The  uniformity  tester  devised  by  the 
Bureau  of  Standards^"  will  probably  not  show  definite- 
ly a  gradual     change  of  permeability  from  the  center 


FIG.     18 — NORMAL    INDUCTION    CURVES,    CHROMIUM    MAGNET    STEEL 
UNK,  SAMPLE  2027. 

Hmax  of  50   and    lOO.     The   Fahy   gives   slightly   low 
values  of  B^  and  H^. 

The  tests  on  the  non-uniform  sample  (Fig.  20) 
are  very  interesting.  For  the  ring  test  results,  the 
values  of  H  are  considerably  too  high  for  the  center  of 


13 

r 

^ 

^ 

IL 

,^ 

r^ 

^ 

|»< 

i^ 

^> 

/ 

// 

y 

// 

? 

» 

/ 

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i. 

6 

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J 

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3 

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jl 

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iurro 

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-ahy 

Pemjeame 

" 

* 

\  k  ^ 

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, 

U' 

berts.pcr    CM, 

0        sp       6U       7fl       ap       90        1 

FIG.    19 — HYSTERESIS    LOOPS,   CHROMIUM    MAGNET   STEEL   UNK, 
SAMPLE  2027. 

to  the  ends,  as  the  effect  would  be  confused  with  the 
ordinary  leakage  effects.  The  only  remedy  is  to  in- 
sure that  the  samples  have  received  uniform  heat  treat- 
ment and  are  of  uniform  material  to  start  with. 

There  is  a  correction  which  may  be  applied  to  the 
Burro>vs  data  due  to  the  magnetizing  effect  of  the  com- 
pensating coils.  This  correction  was  not  applied  ^o 
these  data,  but  approximate  calculations  were  made  in 
two  or  three  cases  and  it  was  found  that  this  effect 
would  account  for  only  a  small  percent  of  the  differ- 
ence between  the  ring  and  Burrows  H  values. 

CONCLUSIONS 

The  following  conclusions  apply  to  the  Fahy  sim- 
plex permeameter  as  at  present  constructed  and  to  the 
Burrows  permeater  having  a  magnetic  circuit  of  the  di- 
mensions shown  in  Fig.  9. 

I — A  simple  and  accurate  method  is  described  for 
checking  the  absolute  accuracy  of  permeameters  taking 
rectangular  bar  samples. 

2— The  limitations  and  accuracy  of  the  Burrows  and 
Fahy  Simplex  permeameters  are  shown  for  certain  specific 
samples. 


August,  1 92 1 


THE  ELECTRIC  JOURNAL 


355 


3 — These  permeameters  will  give  fairly  accurate  normal 
induction  results  for  any  ferro-magnetic  material  at  high 
inductions. 

4 — At  lower  inductions  the  Burrows  normal  induction 
H  values  begin  to  be  too  low  for  material  having  a  maxi- 
mum permeability  of  over  5000.  The  Fahy  permeameter 
gives  too  large  values  of  H  at  moderate  inductions  for  any 
material  except  very  low  maximum  permeability  samples, 
such  as  permanent  magnetic  steel.  The  error  gets  larger  as 
the  maximum  permeability  increases. 

5 — For  material  having  a  maximum  permeability  of 
5000  or  less,  the  Burrows  permeameter  gives  practically  cor- 
rect results  for  ten  kilogauss  hysteresis  loops.  As  the  maxi- 
mum permeability  increases  above  this  figure,  the  observed 
B,  becomes  too  large  and  //c  and  the  hysteresis  loss,  too 
small.  In  general,  the  Fahy  permeameter  apparently  gives 
values  of  B,  and  He  which  are  slightly  low  for  all  materials. 
In  its  present  form  it  is  not  suitable  for  hysteresis  tests  on 
high  permeability  material  due  to  the  fact  that  the  H  coil 
is  too  insensitive  and  due  to  erratic  results. 

6 — In  using  the  Burrows  permeameter,  great  pains  must 
be  taken  to  insure^  that.lhe;^ampj£s:are'.tmi£orni  in  mag- . 
netic  properties.aJong  their  length,' as  otherwis&.very  large 
errors  inay-he.  intraduceA..:' 


P^ 


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z£ 


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ol 

0 

est— Unifom  W 
nsation  Test  CoU 

indin 
s  Ian 

d  2 

+ 

::ompensation  Test  Coils  1  an 
3urTows  Permeameter 
1          1          J 

d  i 

H_ 

JOber 

s  per 

CM. 

FIG.   20 — NORMAL   INDUCTIO.N   CURVES,    NON-UNIFORM    SILICON    LINK, 
SAMPLE  G 

7 — The  Fahy  simplex  permeameter  should  in  general 
be  used  (at  least  in  its  present  form)  only  for  magnetically 
hard  material.  Although  the  results  are  not  quite  correct 
with  the  apparatus,  they  are  very  reproducable.  The  Fahy. 
due  to  the  simplicity  of  operation,  is  especially  suitable  for 
determining  the  effect  of  small  changes  of  heat  treatment 
on  magnetic  properties'. 

8 — Where  accurate  results  are  required  on  high  maxi- 
mum permeability  material,  a  ring  sample  should  be  used. 

Rod  Samples — In  order  to  check  the  accuracy  of 
the  Burrows  permeameter  for  rod  samples,  a  special 
one-half  inch  outside  diameter  rod  was  drilled  through 
its  entire  length  with  a  9/32  in.  hole.  An  exploring 
coil  about  four  inches  long  was  then  wound  on  a  1/8 
inch  diameter  glass  tube,  consisting  of  about  23  000 
turns  of  very  fine  enamelled  wire.  This  coil  was  cali- 
brated by  placing  it  in  a  long  solenoid,  reversing  the 
primary  solenoid  current  and  noting  the  deflection  of  a 
calibrated  fluxmeter  connected  to  the  exploring  coil. 
This  exploring  coil  was  then  placed  inside  of  the  hol- 


low bar  and  the  whole  inserted  in  a  Burrows  permea- 
ter.  H  was  then  read  for  various  values  of  B,  both  by 
means  of  the  exporing  coil  in  the  bar  and  by  the  usual 
method.     The  results  are  given  in  Table  IV. 

The  first  two  points  are  not  very  reliable  due  to  the 
small  readings  on  the  H  coil.  If  a  sufficiently  sen- 
sitive galvanometer  were  available,  such  a  test  as  this 
would  yield  very  satisfactory  check  values  for  lower 
inductions  where  the  departure  from  true  values  may 
be  greatest  with  the  Burrows  apparatus. 

RECOM  M  ENDATIONS 

For  routine  commercial  tests  on  permanent  mag- 
net steel  in  bar  form,  several  of  the  available  commer- 
cial permeameters  are  satisfactory.  For  very  rapid 
^work,  where. comparative  results, only  are  desired,  the 
Koepsel  type  of  apparatus  js  perhaps  as  satisfactory  as 
any.  Where  results  in  absolute  units  are  required  the 
Fahy  simplex  permeameter  is  simple  and  reasonably 
accurate,  if  a  small  correction  is  applied  to  5^  and  He. 
For  research  work,  where  samples  are  to  be  standard- 
ized, or  for  other  reasons  where  absolute  accuracy  is 
required,  the  Burrows  permeameter  is  the  most  satis- 
factory apparatus  available  and  may  be  relied  on  to  a 
TABLE  IV— COMPARATIVE  ROD  TESTS 


H 

H 

Percent 

B 

Burrows 

Coil 

Difference 

11.50 

2. 

1.95 

+2.5 

13-59 

5- 

4.81 

-1-4- 

14.68 

10. 

10.15 

—1-5 

15.21 

20. 

20.4 

— 2.0 

16. 1 1 

SO. 

50.3 

—0.6 

17.27 

100. 

100.8 

—0.8 

fraction  of  one  percent.  An  exception  to  this  state- 
menet  will  have  to  be  made,  however,  in  the  case  of  the 
new  Honda  steels.  Most,  if  not  all  of  the  commercial 
permeameters  on  the  market  can  not  be  operated  at  the 
high  magnetizing  forces  necessary  for  this  material, 
without  serious  overheating. 

For  routine  tests  on  electrical  sheet  material  the 
Fahy  simplex  apparatus  may  be  used  if  results  to  10 
or  15  percent  absolute  accuracy  only  are  required. 
The  Burrows  apparatus  in  its  simplified  form  arranged 
for  the  A.  S.  T.  M.  test  is  probably  the  most  satis- 
factory apparatus  available  if  absolute  accuracy  of  re- 
sults is  required,  coupled  with  fair  speed  of  test,  using 
Epstein  strips.  Some  of  the  other  permeameters  may 
be  used  with  suitable  correction  curves,  but  the  results 
are  more  or  less  open  to  question. 

For  research  work,  except  for  permanent  magnet 
steel,  where  samples  are  to  be  prepared  from  experi- 
mental ingots  or  when  dealing  with  material  having 
maximum  permeabilities  of  over  5000  or  6000  we  be- 
lieve it  advisable  to  use  the  ring  form  of  sample,  due 
to  the  simplicity  of  the  test,  the  ease  of  forming  sam- 
ples and  the  absolute  accuracy  which  may  be  attained. 


"^"Magnetic  and  Other  Properties  of  Iron  Silicon  Alloys 
Melted  in  Vacuo"  by  T.  D.  Yensen,  University  of  Illinois  Bul- 
letin !\i'o.  83,  Eng.  Experimental  Station. 

"Bulletin  of  Bureau  of  Standards,  Vol.  XIV,  No.  i,  April 
6,  1918. 

(To  be  continued) 


Transmission  Line  and  Transforiiiers 


R.  D.  EVANS  and  H.  K.  SELS 

General  Engineers, 
W'estinghouse  Electric  &  Mfg.  Company 


THE  methods  usually  employed  to  include  the 
effects  of  transformers  on  transmission  systems 
consist  of  separate  calculations  for  the  line  and 
for  the  transformers.  In  a .  previous  article*  the 
authors  recommended  the  use  of  general  circuit  con- 
stants, which  include  the  tranfsormers  as  well  as  the 
transmission  line  itself.  In  that  article  the  effect  of 
transformer  exciting  kv-a  was  neglected,  though  the 
effect  of  transformer  impedance  was  included.  It  is 
the  object  of  the  present  article  to  investigate  different 
methods  of  including  transformers  and  to  indicate  the 
desirable  approximations  and  the  magnitude  of  errors 
involved  in  these  approximations. 

A  transformer  may  be  accurately  represented  by 
the  network  shown  in  Fig.  i.  In  this  diagram  T^  re- 
presents a  transformer  impedance  and  I'r  represents 
transformer  shunt  admittance.  Tr  and  1%  arfe  com- 
plex quantities  whose  real  parts  represent  the  copper 
loss  and  iron  loss  and  whose  iniaginar\-  parts  repre- 
sent transformer  reactive  kv-a  and  magnetizing  kv-a 
respectively.  Another  method  which  is  sometimes  em- 
ployed to  represent  a  transformer  is  shown  in  Fig.  2. 


"BTOWW^-v^AAq 


FIG.       I— NETWORK       ACCURATELY    Flc:. 
REPRESENTING     A     TRANSFORMER 


2 —   APPRO.KI.MATE  NETWORK 
FOR    A    TRANSFORMER 


The  use  of  the  network  as  shown  in  Fig.  i  is 
usually  limited  to  the  development  of  formulas  and  to 
those  cases  where  the  voltage  varies  the  exciting  kv-a 
and  where  the  exciting  kv-a  is  of  considerable  impor- 
tance. An  example  of  such  a  case  is  the  problem  of 
determining  the  rise  in  voltage  in  a  transmission  line 
when  the  generator  becomes  self-exciting.  As  the 
transformer  exciting  kv-a  increases  very  rapidly  with 
increase  in  voltage,  it  becomes  an  important  factor  in 
limiting  the  voltage  rise.  The  solution  is  obtained  by 
the  cut  and  try  method,  using  the  constants  of  the 
transmission  circuit  in  conjunction  with  the  voltage- 
exciting  current  curve  of  the  transformer.  The  net- 
work shown  in  Fig.  2  is  rather  generally  employed  for 
determining  voltage  regulation  in  transmission  sys- 
tems involving  transformers  when  the  calculations  are 
made  for  each  part  separately.  This  network,  how- 
ever, introduces  a  small  error. 

The  general  circuit  constants  for  the  networks 
which  are  used  to  represent  transformers  are  fisted  in 
Table  I.  By  employing  these  circuit  constants  the  re- 
lation  between  generator   and   receiver    (primary   and 


secondar}-)     voltages    and    currents    may    be    simply 

stated  as  follows**: — 

£,  =  A„E,  +  B„I, (/) 

/,  =  Ck,E,  +  D„I, \ (^) 

It  will  be  noted  that  the  A^  and  D^  constants  for 
the  two  networks  are  identical  but  that  the  B^  and  Co 
constants  for  the  network  shown  in  Fig.  2  are  incor- 
rect. For  the  usual  cases  the  transformer  impedance 
will  not  exceed  ten  percent  and  the  exciting  kv-a  also 
will  not  exceed  ten  percent.  Hence  the  error  in  the 
Bo  and  Co  constants  will  usually  be  less  than  one 
fourth  of  one  percent.  On  this  account  it  is  usually 
permissible  to  employ  the  network  shown  in  Fig.  2 
instead  of  the  one  shown  in  Fig.  i  and  is  generally 
desirable  for  numerical  solution  b)'  parts. 

The  next  step  is  to  consider  the  general  case  of  a 
transmission  line  with  transformers  at  either  end,  the 
transformers  being  represented  by  their  equivalent  net- 
work as  shown  in  Fig.  3.  The  circuit  constants  for 
the  individual  network  comprising  receiver  trans- 
former, transmission  line  and  supply  transformer  are 
listed  in  Table  II.     From  these  constants  the  general 


FIG.      3 — .NETWORK      FOU      A      TKANSMISSION      UNE,    INCLUDING    THE 
SUPPLY    AND    RECEIVER    TRANSFORMERS 

circuit  constants  A„,  B„,  €„  and  Do  may  be  obtained 
by  substitution  in  equations  (i)  to  (4)  of  page  306  of 
the  Journal  for  July  1921.  The  value  of  these  general 
circuit  constants  are  as  given  under  item  (t)  in  Table 
III.  These  equations  give  the  exact  expressions  for 
the  general  circuit  constants  for  a  transmission  system 
including  transformers  at  both  supply  and  receiver 
ends. 

The  formulas  just  developed  appear  quite  com- 
plicated and  the  next  step  is  to  simplify  them  for  prac- 
tical calculations.     It  has  alreadv  been  pointed  out  that 

r.  F,      .      .    n  F, 


in  general  the  quantities  /  + 


and  I  + 


4  4 

may  be  replaced  by  unity  without  the  error  exceeding 


*Jn  the  TofRXAL  for  July  1921,  p.  306. 


**The  application  of  these  constants  may  be  explained  as 
follows : —  In  a  circuit  of  constant  impedance  characteristics  the 
supply  voltage  in  general  varies  with  receiver  voltage  and  receiv- 
er current.  Hence  we  may  write  equation  (l)  with  .\o  and  Bo  as 
proportionality  constants.  Similarly  the  current  at  the  supply  in 
general  varies  with  receiver  current  and  with  receiver  voltage. 
Hence  we  may  also  write  equation  (2)  .with  G  and  Do  as  pro- 
portionalitv  constants.  Ao  is  the  ratio  of  supply  to  receiver 
voltage  under  open  circuit,  Bo  is  the  equivalent  impedance,  Co  is 
the  equivalent  shunt  admittance,  and  Do  is  the  ratio  of  supply  to 
receiver  currents  with  short  circuited  receiver. 


August,    lt)2I 


THE    ELECTRIC   JOURNAL 


357 


^   percent .     Similarly   /  -(- 


r,  Y 


and    I    + 


r,  I-' 


may  also  be  replaced  by  unity  without  the  error  ex- 
ceeding Yi  percent.  B}-  employing  these  devices, 
general  circuit  constants  for  the  case  shown  in  Fig.  3 
may  be  written  as  given  under  item  (w)  in  Table  III 
and  will  be  accurate  within  one  percent. 

Many  schemes  have  been  proposed  to  produce  a 
simple  but  sufficiently  exact  method  of  including  trans- 
formers at  each  end  of  the  transmission  line.  To 
show  the  relative  simplicity  and  accuracy  of  several  of 
these  schemes  and  also  to.  show  the  characteristics  of 
general  circuit  constants  for  different  types  of  net- 
works. Table  III  has  been  prepared.  All  the  formulas 
given  in  Table  III  are  exact  for  the  networks  shown, 
unless  otherwise  indicated.*  The  accuracy  of  the  ap- 
proximate methods  is  based  on  transformers  having 
ten  percent  exciting  kv-a  and  ten  percent  impedance. 
For  the  cases  where  exciting  kv-a  and  impedance  are 
lower  than  ten  percent  the  amount  of  the  error  will  be 


T.VBLE  I.— CIRCl.'IT  CONSTAXTfi  FOR   TKANSFORMEK 
NETWORKS. 


Circuit 
Constants 

vvvtmotJoovw 
Fig.   1   1 

1       Fig-    2        1 

A„ 

(--^^) 

[-'■>) 

Bo 

<-'-:') 

T, 

Co 

\, 

M^^''^') 

D„ 

(-^^'-) 

(-^-/') 

reduced  accordingly :  e.g.,  with  five  percent  exciting 
kv-a  and  five  percent  impedance  the  error  will  be 
reduced  to  %  of  that  indicated  in  Table  III.  Perhaps  it 
should  be  pointed  out  that  the  product  T^  Y^  for  a 
transformer  in  ohms  and  mhos  is  equal  to  the  product 
of  Tr  and  Y^  expressed  as  a  complex  number  with 
decimals  coi  responding  to  the  percent  impedance  and 
percent  exciting  kv-a. 

In  connection  with  the  various  schemes  given  in 
Table  III  to  represent  transformers,  it  is  to  be  noted 
that  on  setting  the  exciting  admittances  equal  to  zero, 
all  the  formulas  for  each  condition  reduce  to  the  same 
expression.  In  other  words  the  several  formulas  given 
for  each  of  the  different  conditions  differ  only  in  terms 
which  involve  exciting  admittance.  On  this  account 
the  use  of  various  approximate  formulas  is  recom- 
mended in  preference  to  the  use  of  the  exact  solutions, 


*  This  statement  is  based  on  representing  transformers  by 
the  net-work  shown  in  Fig.  i,  in  which  the  primary  and  second- 
ary self  impedances,  when  expressed  in  terms  of  the  same 
voltage,  are  assumed  equal.  These  impedances  may  be  unequal 
but  sufficient  data  is  usually  not  available  to  determine  their 
value  and  on  this  account  it  is  customary  to  assume  the  im- 
pedances equal.  The  error  introduced  into  the  transmission 
constant  by  this  assumption  is  e.xceedingly  small. 


because  the  shunt  admittance  of  a  transformer  is  not 
known  with  any  high  degree  of  exactness  and  in 
general  the  shunt  admittance  will  vary  somewhat  with 
the  different  load  conditions. 

Occasionally  it  has  been  proposed  to  add  trans- 
former series  impedance  directly  to  the.  transmission 
line  impedance  and  the  transformer  shunt  admittance 
directly  to  the  transmission  line  shunt  admittance  and 
to  use  these  new  values  for  obtaining  the  circuit  con- 
stants for  the  transmission  system.  This  method  is 
not  to  be  recommended  because  '  it  ■.  does  not  have  a 
mathematical  basis,  and  because  it  is  not  as  convenient 
to  employ  as  the  approximate  solution  given  in  Table 
III,  particularly  in  case  the  general  circuit  constants 
are  required  for  two  or  more  transformer  combina- 
tions at  either  the  supply  or  receiver  end. 

It  has  also  been  proposed  to  add  transformer 
series  impedance  to  the  B  constant  of  the  transmission 
line  to  obtain  the  Bo  constant  and  to  add  the  trans- 
former shunt  admittance  to  the  C  constant  to  obtain 
the  Co  constant.  This  is  a  very  approximate  methoH 
a:id  may  give  rise  to  an  error  much  greater  than  one 
percent,  as  may  be  readily  shown  from  the  circuit  con- 

TAULE   II.— CIRCUIT  COXSTAXTS   FOR  FIC,.  3. 


T.Y. 
A2=A             A3=K    -— 

/      T,  Y,  \ 

B2=B 

B3-^T,(,.-VV) 

Ci  =  Y, 

C2  =  C       1      C3=Y, 

„      ,    T,  Y, 

T,  y, 

D2=A             D3=l^       -- 

stants  for  a  particular  case  e.g.,  item  (t)  in  Table  III. 
This  method  is  not  to  be  recommended  because  of  its 
inaccuracy. 

A  study  of  Table  III  shows  that  for  the  problems 
involving  transmission  lines  and  transformers,  two 
general  methods  of  solution  may  be  employed.  Con- 
ditions given  in  items  (n),  (r)  and  (v)  may  be  solved 
by  including  the  exciting  admittances  as  part  of  the 
transmission  system  or  as  part  of  the  load  on  the  sys- 
tem. If  the  exciting  admittance  is  considered  as  part 
of  the  transmission  system,  the  solution  is  given  under 
items  (n),  (r)  and  (v).  If  the  exciting  admittance 
is  considered  as  part  of  the  load  on  the  system,  the  re- 
ceiver transformer  exciting  kv-a  is  added  to  the  re- 
ceiver load  and  the  supply  transformer  exciting  kv-a 
is  treated  as  a  separate  load  on  the  supply  and  the 
circuit  constants  given  in  Table  III  under  items  (i), 
(j)  and  (k)  will  be  employed.  Between  these  two 
methods  there  is  little  choice,  though  the  method  of 
considering  exciting  kv-a  as  part  of  the  load  on  the 
system  has  some  advantage  in  that  the  circuit  con- 
stant formulas  are  simpler  and  the  method  slightly 
more  accurate,  and  that  changes  in  exciting  kv-a  with 
changes  in  voltage  are  more  readily  taken  into  account, 
while  the  other  method  gives  a  complete  solution  and 


358 


THE   ELECTRIC  JOURNAL 

TABLE  III— CIRCUIT  CONSTANTS  FOR  DIFFERENT  NETWORKS 


Vol.  XVIII,  No.  8 


§  Type  of  Network 


Series  Impedance 


•(.•^■;') 


'•('•'•^) 


Transformer, Approximate  Error  0  5 


Transformer,Approximale  Error  0.5'. 


Transformer,  Apprc 


E.         A.  a  C,  A  E, 

Transmission  Line  (T  L  I 


C-.4, 


Transmission  LincyExi 


fc,       A.  8.  C.  A    T.      E, 
T  L.  and  Series  Impedancr 


T  L  and  Senes  Impedan. 


B*A(T,    -T.   )     CT,  T. 


T  L  and  Series  Imoedam 


Hems  let  Plus  yh) 


M..^-;-). 


«(,.T.^^.^,.T^) 


c(.v-)- 


*('-\>"-(-^-^| 


Items  (dl  Plus  th 


1      T,  YA  /     T,  Y,\ 


,(,.I.v.)  +  ^T. 


c(.-',^.)^-.(,.-.7-) 


4-^KcT. 


All-T,  Y,  )-BV, 


ai-T,  Y,  )•  AV, 


Items  lel  Plus  ihl 


•r  Transformer  ApprOM 
■:  Network  Error  .5^ 


.    .(.^•;-)^T.(..V^, 


jw. 


Hems  (hi  Plus  td) 


3: 


•Vat^.-.;0 


4..^-;-KcT. 


b(i.^-;-}.at. 


c(,.:^,^>.v. 


A(.I-f^KBV. 


Transmission 
Iransformer,        Ex. 


C(,.LV.),,,.(,.T.V,) 


a(,.V->bv.(.V-) 


Transmission    Line     and    Supply 
Transformer, Approximate  Error  0.35 1 


Transformer,  Appro: 


.4,J.^)(..T^),..V.(.:^^BV.0.I^X-^KCT.(..IS^-) 


Transmission  Line.  Supply 
and  Rec«ivef  Transformer 
Approximate  Network 


¥•  cl  A,   Jf  cl  a'i      4 


A,  -a^i.t,  Y,  I-Y,  T.]+BY,  +  CT,iI-T,  Y,  I 

B,  .B+A(T,  .T.  )  'CT,  T. 

C,  -CII.T,  Y,  Kl-T.  Y.  )+a[y.(|-T.  Y.  )+Y.|1.T,.Y,   i]+  BY,  Y. 

D,  -a||*T.  Y.  )+Y,T,]+BY.  +  CT,(|tT.  Y.  ) 


A,.A+CT,+  Y,(AT,  tB) 
B,.B-A(T,   'T.  )  -CT,  T. 

C,  -C+  BY,  Y,+  A(Y,  -Y.  )  . 

D,  -A  +  CT,  +V,(B+AT,) 


Ao     (A, +C,T.  )   (A|  »C,  T„)-(B,-A,  T.  )(A,  Y„-C,  ) 

Bo  -(A,  .CT.  )   (Bi  .A,  T.  •  A,  T„  -C,  T„T,  )+(B,  *A,  T.  )  (A,  -C,  T,  .Y„B,   .Y„A,  T,  ) 

C  -C.CA,  ♦C,T„).A,(A,  Y„.C,  ) 

D,  -(At  *C|  T,  )(a,  »C,  T„)+(Bi  *A,  T,)  (A,  Y„-C,  ) 


,  Bi  *A;B| 


B,  Dj  ♦Bi  Di 


c.-Ct.c,.(li^M^         0.-51^ 


Transmission  Line  and  Supply  and 
Receiver  Transformer, 


Approximate  Error  0.25^ 


l-i 


Two  Transmission  Lines  m  Series 
and  Three  Transformers,  Approximate 
Error  l°C  Note  Receiver  and  Supply 
Transformer  Exabng  Kv-a  Considered 
as  Part  of  Ihe  Loads  ^ 


Two  Transmission  Systems  In  Par 
allel^xact 


E.     A.E,-E,,.  E,-D.E.-B...  V.(,.?|.^....)  .3.,(„?X.|i|!  )  'c-Y  (l.f^.fi^^.-.- ) 


August,  1921 


THE   ELECTRIC   JOURNAL 


359 


does  not  require  a  correction  for  each  load  condition. 
The  case  of  two  transmission  lines  in  series  con- 
nected through  a  transformer  or  an  auto-transformer 
is  given  under  item  (x).  Here  the  solution  is  obtained 
by  employing  the  circuit  given  under  item  (x)  and  by 
considering  the  exciting  kv-a  of  the  receiver  trans- 
formers as  part  of  the  receiver  load  and  the  exciting 
kv-a  of  the  supply  transformer  as  a  separate  load  on 
the  supply.  This  case  is  a  good  example  to  show  the 
possibilities  of  obtaining  relatively  simple  expressions 
for  circuit  constants  for  complex  networks  by  employ- 
ing suitable  combinations  of  approximate  formulas 
given  in  Table  III.     Item  (y)  really  covers  the  general 

TABLE  IV— METHOD  OF  CALCULATING  CIR- 
CUIT CONSTANTS 


Condition 

Item  Numbei-sii.  Table  Ill- 

Exact 
Solulioii 

ApiJi-oximate 
SohHioiis 

Transmission  line  and 
receiver  transformer 

1                   r  or  1  * 

Transmission  line  and 
supply    transformer 

P 

s  or  j  * 

Transmission  line  and 
both  receiver  and  supply 
transformers 

t         1 

0  or  k  * 

*These  methods  require  that  the  transformer  exciting  kv-a 
be  considered  as  part  of  the  load.  With  the  other  methods 
transformer  exciting  kv-a  is  considered  as  part  of  the  transmis- 
sion system. 

case  of  two  networks  in  parallel.  The  relation  that 
the  two  transmission  systems  have  the  same  terminal 
voltages  is  sufficient  to  determine  the  equivalent  con- 
stants covering  both  lines.  For  each  of  these  cases, 
items  (x)  and  (y),  the  voltage  of  the  two  transmission 
systems  may  be  different,  and  it  becomes  necessary  to 
express  the  constants  of  both  systems  in  terms  of  the 
same  voltage  before  the  general  circuit  constants  for 
the  systems  as  a  whole  can  be  determined.     For  this 


purpose  the  constants  A  and  D  will  be  the  same  for 
any  voltage,  the  B  constant  will  be  changed  inversely 
as  the  square  of  the  ratio  of  the  two  voltages  and  the 
C  constant  directly  as  the  square  of  the  ratio  of  the 
voltages. 

SUMMARY 

It  is  now  possible  to  indicate  the  best  methods  of 
taking  transformers  into  account  in  transmission  prob- 
lems. Where  the  highest  degree  of  accuracy  is  re- 
quired the  exact  solution  should  be  employed  but  for 
the  usual  case  approximate  solutions  are  adequate. 
Table  IV  indicates  the  most  useful  solutions,  which 
are  given  in  Table  III. 

CONCLUSION 

The  use  of  general  circuit  constants  applicable  to 
the  transmission  system  as  a  whole  is  recommended. 
The  use  of  these  constants  simplifies  the  calculation 
for  even  one  load  condition,  and  also  provides  the  con- 
stants in  the  form  most  convenient  for  use  in  calculat- 
ing other  load  conditions.  The  use  of  circuit  constants 
more  readily  permits  the  use  of  desirable  approxi- 
mations. 

Application  to  Circle  Diagrams — A  further  advan- 
tage of  the  use  of  general  circuit  constants  is  their  ap- 
plication to  the  graphical  solution  of  transmission  prob- 
lems involving  transformers.  The  Dwight  or  other 
circle  diagrams  are  applicable  to  this  problem  without 
change  if  general  circuit  constants  are  employed  in- 
stead of  constants  applicable  to  the  transmission  line 
alone. 

CORRECTION 
In  the  Journal  for  July   1921,  p.  307,  equation   11   should 
read  E,  =  D„  E,  —  J!»  f,  and  equation  12  should  read  /,=  —Ci\ 
Es  +  .^H  h       On  p.  308,  in  the  appendix,  first   equation,  ft'.*'.  «• 
should  read  I'^s.  j  ir. 


£:<:€avatJBy^ 


..'^ 


L.  C.  McLURE 

Industrial  Sales  Department, 
Westinghouse  Electric  &  Mfg.  Company 


.i\ 


Vm 


ia\ 


THE  City  of  Dayton,  Ohio  and  the  surrounding 
country,  lying  in  the  Miami  Valley,  has  always 
been  subject  to  periodic  floods.  The  disas- 
trous flood  in  the  spring  of  1913,  which  caused  con- 
siderable loss  of  life  and  property,  so  crystallized  the 
public  opinion  that  the  adjoining  counties  organized 
the  Miami  Conservancy  District,  to  carry  out  an  ex- 
tensive program  of  excavation  and  dam  construction 
to  prevent  such  floods  in  the  future.  Earth  dams  are 
being  thrown  up  which  will  extend  across  the  valley  to 
the  hills  on  either  side.  Concrete  covered  openings  are 
left  in  the  dams,  allowing  the  normal  flow  of  water  to 
pass.  In  periods  of  high  water,  the  excess  water  will 
be  retarded  above  the  dams,  allowing  it  to  flow  through 
at  a  safe  rate. 


As  the  surface  of  the  land  is  rather  flat,  with  roll- 
ing hills,  the  dams  are  long  and  require  a  large  amount 
of  material  for  their  construction.  Work  on  this  pro- 
ject was  started  during  the  war,  under  unfavorable 
labor  conditions ;  labor  being  expensive  and  hard  to  get 
at  any  price.  These  conditions  demanded  the  use  of 
excavation  methods  which  requires  the  smallest  num- 
ber of  workmen. 

Drag-line  excavators  are  employed  to  dig  the  ma- 
terial from  the  river  bed  and  the  valley  above  the  dam 
site  and  load  it  into  dump  cars  having  a  capacity  of  12 
cubic  yards.  The  loaded  cars  are  hauled  to  the  base 
of  the  dam  where  the  cars  are  dumped.  A  strong 
stream  of  water  is  then  played  on  the  pile  of  loose  ma- 
terial, carrying  away  the  earth  held  suspended  in  the 


s6o 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


water.  This  mixture  of  water  and  earth  is  pumped  to 
the  top  of  tlie  dam;  \\-here  the  water  runs  off,  leaving 
the  earth  deposited  on  die  dam.  A  drag-line,  located 
on  the  top  of  the  dam,  is  used  to  place  the  material 
where  it  is  needed,  and  to  give  the  sides  of  the  dam 
their  proper  slope. 

The  electric  drag-line  excavator  is  constructed 
somewhat  similar  to  a  steam  shovel.  A  car  containing 
the  main  operating  machinery  is  mounted  on  wheels  or 
caterpillar  tractors.  In  the  front  part  are  located  the 
winding  drums  and  their  driving  motors..  In  the  rear 
of  the  car  are  located  the  control  panels  for  the  mo- 
tors, and  u.sually  a  bank  of  transformers.  A  long 
boom  projects  upward  and  forward 
from  the  front  end  of  the  machine. 
The  cables  from  the  winding  drums 
run  over  sheave  wheels  on  the  ex- 
treme end  of  this  boom  and  control 
the  movements  of  the  excavating 
bucket. 


phase,  60  cycles,  440  volts  and  are  all  of  the  heavy  du- 
ty, reversing  typei  ■  They  are  built  with  extra  large 
bearings  and  shafts  to  make  them  suitable  for  the 
severe  service;  and  are  designed  with  small  armature 
diameter,  giving  the  low  fly  wheel  effect  which  is  so  de- 
sirable in  this  service,  where  sudden  stops,  starts  and 
frequent  reversing  is  required. 

Single-phase,  75  kv-a  transformers  are  used  to 
stepdown  the  2300  volts  power  supply  to  the  voltage 
used  on  the  motors.  A  bank  of  these  transformers  is 
mounted  on  the  ground  near  each  drag  line,  separate 
mounting  being  preferred  by  the  engineers  of  the  Con- 
sei-vancy  District.     The  low-voltage  power  is  carried 


The  bucket  is  pulled  out  to  the 
end   of   the   boom   and   dropped   into 
the   material.     It   is   then   dragged  in 
toward    the    car    until    it    is    loaded. 
No  thrusting  motion  is  used,  as  in  a 
shovel,  but  the  weight  and  shape  of 
the    bucket    are    relied    on    to    fill    it. 
The  loaded  bucket  is  then  hoisted  and  the  whole  drag 
line  is  turned  until  the  bucket  is  in  the  right  position 
for  dumping,  which  is  accomplished  by  lowering  the 
open  end  and  letting  the  material  fall  into  the  car. 

Two  motors  are  mounted  in  the  car  body.  The 
hoist  motor  is  connected  through  clutches  to  two 
drums,  one  of  which  hoists  and  lowers  the  bucket,  while 
the  other  pulls  the  bucket  through  the  material.  The 
second  motor  rotates  the  drag-line  between  the  digging 
and  dumping  positions. 

The   Conservancy  District   purchased,  along   with 


FIG.  2 — DR.\C  LINK  USEn  FOK  KXC.WATING 

to  the  drag  line  by  a  flexible  cable,  and  when  the  ma- 
chine moves  any  considerable  distance,  the  transform- 
ers are  disconnected  and  moved  to  the  new  location. 

Full  magnetic  control  is  used  for  both  main  mo- 
tors. The  master  switches  and  control  levers  for 
brakes  and  clutches  are  conveniently  grouped  at 
one  point  at  the  front  of  the  car.  Only  one  operator 
is  required,  who  is  so  located  that  he  can  watch  the 
various  movements  of  the  bucket.  A  motor  driven  air 
compressor  supplies  air  for  operating  clutches  and 
brakes. 

These  motor  driven  drag  lines  have  been  in  serv- 
ice about  three  years  and  have  given  very  satisfactory 
performance.  The  power  consumption  of  one  of  the 
machines  used  on  this    project    is    given    in    Table    I. 

T.\BLE  I— POWER  CONSUMPTION 


Cii.     Yards     excavated 

Kw.  hours  used 

Kw.  hours  per  cu.  yd. 


77050 

60500 

0.78 


72  136     I     35  310 

45  700         42  600 

0.63     I I.2._ 


FIG.   I — DRAG  Ll.XE  USED  FOR  SMOOTHING  THE  SIDES  OF  A  FILL 

other  excavating  machinerj',  six  Bucyrus  motor-driven 
drag-lines.  Four  of  these  are  Class  24  size,  having 
200  hp  motors  on  the  hoist  motion,  and  100  Up  motors 
on  the  swing  motion.  The  other  two  are  Class  175-B 
size  on  which  250  hp  hoist  motors  and  125  hp  swing 
motors  are  used.     These  motors  are  wound  for  three- 


These  records  were  taken  on  a  Bucynus,  Class  24  drag 
line,  deepening  a  river  bed,  loading  gravel  into  cars  of 
12  cubic  yard  capacity.  The  three  columns  show  the 
total  volume  of  material  handled,  and  kilowatt-hours 
used  per  month  for  three  consecutive  months. 

The  amount  of  labor  required  to  operate  these  ma- 
chines is  small.  Each  drag  line  requires  one  operator 
and  a  helper  who  oils  the  machinery  and  attends  to 
other  minor  duties.  A  considerable  saving  is  made 
over  the  steam  driven  machines,  because  no  men  are 
required  for  firing  the  boilers,  throwing  coal  up  to  the 
firing  platform,  or  for  bringing  coal  to  the  drag  line. 


Augustj  1921 


THE    ELECTRIC   JOURNAL 


.361 


Also,  no  coal  cars  are  necessary,  leaving  the  tracks  and 
trains  free  for  uninterrupted  movement  of  material 
away  from  the  excavator. 

The  necessity  for  maintaining  a  supply  of  pure 
boiler  water  does  not  exist ;  and  this  is  of  great  import- 
tance  in  winter  months  when  frozen  pipe  lines  will 
cause  shut  down  of  a  steam  driven  machine.  The  mo- 
tor driven  machine  has  no    stand-by   losses    when    not 


operating;  and  when  operations  are  resumed  after  an 
over-night  or  noon-time  shut  down,  work  can  he 
started  immediately  upon  closing  the  line  switch,  it  not 
being  necessary  to  wait  imtil  a  boiler  gets  up  steam 
pressure.  For  these  reasons,  these  motor  driven  drag 
lines  have  made  a  record  for  low  operating  costs  and 
for  continuous  operation,  which  shows  them  to  be 
nnich  superior  to  similar  steam  driven  machines. 


Tho  ^(aJlTrf<^ctI(^o  of  C©5)por  ^7iro  and  Straii^l 

R.    KENNARD 

Electrical   Superintendent 

Anaconda  Copper  Alining  Co., 

Great  Falls,  Mont. 

COPPER  wire  and  strand  play  a  very  important  after  entering  the  first  groove,  which  is  in  the  top  and 

part    in    the   electrical    field   and   to    those   who  middle    rolls,    passes    through    this    groove    and    drops 

have   not  had   the   opportunity   of   seeing   them  down    into    position    for   entering   the    second    groove, 

manufactured,  a  brief  description  of  the  several  pro-  which  is  in  the  middle  and  bottom  roll,  and  passes  back 

cesses  will  be  of  interest.     Refined  copper,  in  its  com-  through  this  second  groove  to  the  side  of  the  mill  from 

mercial  form,  is  cast  into  bars  which  are  usually  about  which  it  started.     It  is  then  raised  into   position   for 

four   inches   square,   fifty  inches  long  and  weigh  220  entering  the  third  groove,  which  is  next  to  the  first 

pounds.     The  average  analysis  of  wire  bar  is: —  groove.     In  this  way,  it  passes  back  and  forth  through 

Copper 99.96  the  mill  seven  times,  each  pass  reducing  the  cross-sec- 

Sike^*^" aoo72  'i°n  ^^  ^^^  t)^''  ^""^  increasing  its  length. 

Arsenic  0.0017  After  leaving  the  roughing  mill,  the  bar  passes  to 

Antimony O.OO16  ,        .                  ,.                 ,    ^    .   ,  .              ...                 .     .            ,    r- 

Nickel  &  Cobalt 0.0006  the  intermediate  and  finishing  mills,  consisting  ot  nve 

Bismuth  0.0004  ^^^  g[-^  paiTs  of  rolls  respectively,  each  alternate  pair 

Iron  0.0006  .         .                  ....              ,,„          ^,            J 

Selenium   0.0009  rotating  in  opposite  directions.     When  the  rod,  as  it 

Sulphur 0.0020 

100.0000 

The  wire  bars  are  first  placed  on  a  table  in  the 
rear  of  a  bar-heating  furnace  and  a  pusher,  operated 
by  compressed  air,  moves'  them  along  into  the  fur- 
nace, which  holds  100  bars  lying  side  by  side  through-  .a^^^^^^^^Ki-  .niiliUWH  ill  Hill, Willi  i 
out  its  length.  The  furnace  is  heated  by  fuel  oil 
burners  located  at  the  opposite  end  from  that  at  which 
the  bars  enter.     The  bars  are  taken  out  of  the  furnace 

through  a  door;  located  near  the  heating  chamber.     As  pj,.    j i,e.\lk\l  \itu   ui   kulli-m,  -mill 

fast  as  they  are  taken  out,  more  bars  are  pushed  in  at 

the  rear  end  and  the  bars  alreadv  in  the  furnace  are  comes  from  the  roughing  mill,  passes  through  the  first 

moved  toward  the  heated  end  and  the  discharge  door.  Pair  of  rolls  in  the  intermediate  mill,  a  man  catches 

The  heat  travels  the  length  of  the  furnace,  the  smoke  the  end  of  it  with  a  pair  of  tongs  and  starts  it  back 

and  gases  going  out  through  a  flue  at  the  rear  end.  through  the  next  pair  of  rolls,  the  rod  running  in  a 

The  bars  are  taken  out  of  the  furnace  at  the  rate  loop  on  an  inclined  iron  floor,  which  is  on  both  sides 
of  100  an  hour.  Thus  it  takes  an  hour  for  a  given  of  the  rolls.  This  process  is  repeated  until  the  rod 
bar  to  travel  through  the  furnace.  In  this  way  the  ''^as  run  through  all  the  different  pairs  of  rolls, 
heating  takes  place  gradually  and  can  be  controlled  so  The  wire  drawing  process  consists  of  drawing  the 
as  to  have  each  bar  at  the  proper  rolling  temperature  rod  through  a  succession  of  dies  until  its  diameter  has 
when  it  reaches  the  discharge  door.  The  bars  are  been  reduced  to  the  diameter  of  the  wire  required, 
taken  out  at  the  discharge  door  by  a  pair  of  tongs  sus-  For  the  larger  sizes  of  wire  the  rod  is  drawn  through 
pended  from  a  trolley  which  runs  in  line  with  the  first  one  die  at  a  time  until  it  is  finished,  but  for  smaller 
groove  in  the  rough  rolling  mill.  This  mill  consists  of  wires  the  rod  is  placed  on  a  continuous  wire-drawing 
three  rolls  18  inches  in  diameter  and  64  inches  long,  machine  and  is  drawn  through  a  succession  of  dies  at 
one  above  the  other,  driven  from  a  motor  through  a  the  same  time.  These  machines  have  a  series  of  draw- 
reducing  gear  unit  and  a  set  of  pinions.  The  direc-  ing  rolls,  each  of  which  draws  the  wire  through  one 
tion   of    rotation   of   these   rolls   is   such    that    the  bar,  die,  after  which  it  passes  through  the  next  smaller  die 


362 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


and  on  to  the  next  drawing  roll,  this  being  repeated 
until  it  passes  through  the  finishing  die.  It  is  then 
either  drawn  into  a  coil  on  a  revolving  block,  or  drawn 
and  wound  on  a  reel  which  is  so  driven  as  to  take  the 
wire  as  it  is  drawn  through  the  last  die.     The  drawing 


FIGS.    2,    3    AND    4 — POWER    CURVES 

Showing  kilowatts  required  for  the  different  passes  through  the  various  rolls 
rolls  and  blocks  on  these  machines  run  at  increasing 
speeds  proportioned  so  as  to  take  care  of  the  increas- 
ing length  of  wire  produced  by  the  elongation  due  to 
drawing. 

The  process  of  drawing  the  rod  through  the  dies 
to  the  finished  size  hardens  the  copper.  Wire  drawn 
on  these  machines  is  shipped  as  "hard  drawn  wire". 
When  "soft  drawn  wire"  is  required  the  hard  wire  is 
passed    through    an   aniiealinsr    furnace    which    renders 


tapered  hole  and  are  reamed  to  exact  size  by  hand. 
After  the  hole  in  the  die  wears  and  becomes  too  large 
for  a  given  size  of  wire  it  is  then  reamed  out  to  a  larger 
size,  this  process  being  repeated  many  times. 

The  usual  variation  in  diameter  allowed  on  all 
wires  of  sizes  No.  lo  and  smaller  is 
one  one-thousandth  of  an  inch.  Not 
only  accuracy  as  to  size  is  required, 
but  it  is  necessary  to  shape  the  die 
so  that  it  will  hold  its  size  within 
this  limit  after  withstanding  the 
wear  of  drawing  a  wire  as  long  as 
four  miles  from  one  rod. 

For  making  trolley  wire   to   be 
furnished  in  long  lengths,  it  is  nec- 
essary   to   join    a   number    of    rods, 
which  is  done  by  brazing  them  with 
silver  solder  before  drawing.     A  suf- 
ficient number  of  rods  are  brazed  so 
as   to    produce    a   certain    length  of 
finished    wire.     In    many   cases  this 
length  is  one  mile,  and  the  weight  of 
the   wires   varies  from    1687  pounds 
for   i-o  size  to  3.582  pounds  for  4-0 
size.     After  being  brazed,    the  rods 
are  drawn  through  two  or  more  dies 
continuously    and    are   wound   on  a 
reel   at   the   same   time.      The    dies 
used      for     making     round     trolley 
wire   are   made   of   chilled  iron,  the 
same    as    the    dies    for    making    smaller    wires.     For 
grooved,  figure  8  and  other  shapes  of  trolley  wire,  the 
dies  are  made  of  the  best  quality  of  steel  suitable  for 
this  purpose.     They  are  carefully  punched  and  sized, 
then   hardened   and   polished.     Under   the   best  condi- 
tions a  die  will  draw  about  five  miles  of  wire,  after 
which  it  has  to  be  remade. 

In  the  manufacture  of  strand  or  cables,  the  wire 
compcisin^  the  strand  or  cable  may  be  hard,  medium 


FIG.    5 — ROUGHING    ROLLS 

Showing  flywheel  and  discharge  end  of  heating  furnace. 

the  wire  soft  and  pliable.  Medium  hard  wire  is  pro- 
duced by  drawing  the  rod  to  a  certain  size  which,  after 
being  annealed,  will  require  just  the  necessary  amount 
of  further  drawing  to  produce  the  degree  of  hardness 
specified.  The  dies  used  for  wire  drawing  are  small 
circular  dies   made   of   chilled   cast   iron,   cast   with   a 


PIC.    6 — INTERMEDIATE  AND    FINISHING    ROLLS 

With  east  loop  pit  in  foreground. 

hard  or  soft.  The  wire  is  either  drawn  on  iron  reels 
or  wound  on  reels  from  coils  and  these  reels  are  placed 
in  the  stranding  machines.  Strand  such  as  is  used 
for  power  transmission  lines  is  made  on  a  high-speed 
machine  which  will  lay  up  six  wires  around  a  center 
wire. 


August,  192 1 


THE   ELECTRIC   JOURNAL 


363 


Another  machine  consists  of  two  revolving  circu- 
lar frames  which  usually  revolve  in  opposite  directions 
and  in  which  iron  reels  containing  the  wire  are  placed. 
The  first  frame  holds  six  reels,  and  as  this  frame  re- 
volves, the  six  wires  are  laid  around  a  center  wire 
which  passes  through  the  center  of  the  frame.  These 
seven  wires  then  form  the  core  of  the  cable  and  pass 


finishing  rolls,  thus  requiring  no  space  on  the  main 
floor.  In  this  substation  is  located  the  main  2200  volt 
bus  with  its  accompanying  oil  circuit  breakers,  relays, 
instruments,  etc.,  the  main  contactor  panels  for  the 
roll  motors,  transformers  for  reducing  2200  volts  to 
440  volts  for  use  in  the  smaller  motors  throughout  the 
mil!   nrifl   lic:litinq-  t-"i'icformers.     The  process  of  wire 


FIG.  7 — A  FOUR  BLOCK  DRAWING  BENCH 

through  the  center  of  the  next  frame.  The  twelve 
wires  which  this  second  frame  holds  are  laid  around 
this  core  of  seven  wires,  making  a  19  wire  srand  or 
cable. 

Another  machine  of  the  same  type  but  with  three 
frames  holding  6,  12,  and  18  reels  each,  makes  a  cable 
of  three  layers  or  a  total  of  37  wires.  If  required,  the 
cable  of  37  wires  is  passed  through  the  center  of  an- 
other machine  and  a  further  layer  of  24  wires  is  added, 
making  a  6i-strand  cable.  It  is  also  possible  to  pass 
this  through  another  machine,  adding  30  wires,  if  a 
cable  of  91  wires  is  desired. 

The  completed  cable  passes  around  a  revolving 
drum  which  takes  it  up  as  fast  as  it  is  twisted.  It  then 
passes  from  the  drum  to  the  reel  on  which  it  is  to  be 
shipped,  which  is  driven  so  as  to  take  it  from  the  drum 
at  the  proper  speed. 

The  revolving  frames  are  driven  through  revers- 
ing and  interchangeable  gears,  as  is  the  take-up  drum. 


FIG.    8 — FINISHING   END   OF   A    TEN   DIE   DRAWING   MACHINE 

making  is  admirably  adapted  to  individual  motor 
drive,  and  this  is  carried  out  with  very  few  exceptions. 
The  roughing  rolls  are  connected  through  a  flexi- 
ble coupling  and  450  to  no  herringbone  gear  reduc- 
tion to  a  500  horse-power,  2200  volt,  450-442  r.p.m., 
wound  rotor  motor  equipped  with  flywheel.  The 
power  used  varies  from  80  to  460  kw  for  red  hot 
rods,  as  shown  in  Fig.  2.  If  a  rod  is  held  up  for  even 
a  short  period  during  its  travel  through  the  rolls  and 
allowed  to  cool  slightly,  the  power  requirements  are  at 
least  doubled.  These  heavy  power  swings  cause  an 
appreciable  increase  in  the  slip  of  the  motor,  thus 
bringing  the  flywheel  into  service  to  help  over  the  peak. 
With  the  paper  speed  increased,  as  shown  in  Fig. 
2,  a  very  clear  analysis  is  given  of  the  power  require- 
ments for  the  different  passes.  Following  through  the 
first  cycle,  during  which  operation  was  retarded  to 
allow  one  bar  to  leave  rolls  before  second  bar  was 
started,  the  bar  was  of  normal  heat.     On  passes  i,  2, 


FIG.  9 — STARTING  END  OF  A  VHREE  FRAME  37  WIRE  STRANDER 

The  relation  of  the  speed  of  the  frame  to  the  speed  of 
the  drum  determines  the  pitch  or  lay  of  the  wires  in 
each  layer,  this  lay  usually  varying  with  the  number 
of  wires. 

POWER  REQUIREMENTS 

The  power  is  obtained  from  a  substation  located 
under  the  main  floor  and  east  of  the  loop  pit  of  the 


FIG.    10 — FINISHING  END  OF  STRANDER   SHOWN    IN   FIG.    9 

3,  4,  &.  ^  the  bar  passes  completely  through  the  rolls  on 
each  pass.  However,  by  this  time  the  bar  has  been 
elongated  to  such  an  extent  that  it  is  entered  in  pass  7 
before  leaving  pass  6.  After  this  cycle  was  obtained, 
the  second  bar  was  started  and  rolls  continued  under 
normal  operation,  that  is,  the  new  bar  started  in  pass 
/  while  the  preceding  bar  is  continuing  through  pass  7. 


364 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


The  intermediate  rolls  are  connected  to  a  similar 
motor.  '  However,  the  flywheel  is  omitted  as  the  power 
swings  are  of  less  magnitude  and  they  do  not  require 
its  balancing  effect.  In  Fig.  3,  as  in  Fig.  2,  the  opera- 
tion was  retarded  for  a  moment  to  allow  two  rods  to 
make  the  entire  travel  singly  then  continue  under  nor- 
mal operation.  The  rod  has  now  elongated  to  such 
an  extent  that  the  end  does  not  leave  the  pass  /  until 
after  pass  4  is  made.  This  is  continued  through  nor- 
mal operation  with  the  exception  that  the  second  rod 
is  entered  in  the  pass  i  before  the  previous  rod  is  out 
of  pass  4,  thus  giving  the  same  peak  and  increasing  the 
load  factor  on  the  motor. 

The  finishing  roll  motor  also  has  no  flywheel  as 
its  use  is  unwarranted  as  can  be  seen  from  Fig.  4. 
The  power  requirements  of  the  different  passes  for  a 
single  rod  are  shown  when  the  second  rod  enters  the 
pass  I  just  as  the  previous  rod  is  leaving  it.  This 
allows  two  rods  to  be  in  the  mill  almost  continuously, 
giving  a  comparatively  constant  load. 

Control  for  each  of  the  motors  consists  of  a  re- 
versing controller  which  operates  the  control  circuit 
for  two  triple-pole  oil-immersed  electrically-inter- 
locked contactors  mounted  behind  the  main  panel,  one 
for  forward  and  one  for  reverse  direction  of  the  rolls, 
also  for  eight  electrically  interlocked  accelerating  con- 
tactors mounted  on  the  front  of  the  panel.  The  ac- 
celerating contactors  are  in  turn  controlled  by  three 
current  limit  relays  to  insure  proper  acceleration  of  the 
motor  regardless  of  the  speed  with  which  the  con- 
troller handle  is  moved  to  eitlier  the  forward  or  the 
reverse  position.  When  number  eight,  or  the  final  ac- 
celerating contactor,  is  closed,  it  opens  the  control  cir- 
cuit of  the  previous  contactors  thus  opening  the  main 
contactors. 

There  is  a  maximum  torque  button  installed  near 
the  controller  to  close  No.  3  contactor  and  open  No. 
8,  thereby  cutting  the  proper  amount  of  resistance  in 
the  rotor  circuit  to  give  maximum  torque.  When  the 
button  is  released  the  contactors  successively  close  back 
to  normal  or  running  position  again.  There  are  several 
stop  buttons  installed  at  different  points  on  the  rolls 
for  use  in  emergency. 

There  are  two  exhaust  systems  for  the  rolls,  the 
fan  of  each  being  driven  by  a  10  horsepower,  440  volt, 
1200  r.p.m.,  squirrel-cage  induction  motor  and  piped 
to  a  funnel  shaped  opening  above  each  pass,  thus  re- 
moving the  smoke  and  copper  dust  from  the  operators. 

The    drawing    benches    are    connected    direct    or 


tlirough  silent  chain  drives  to  2200  volt  induction  mo- 
tors either  squirrel  cage  or  wound  rotor,  as  required. 
The  earlier  benches  used  the  wound  rotor  motors  due 
to  higher  starting  torque  and  gradual  acceleration. 
However,  practice  has  shown  that  the  squirrel  cage 
motor  is  well  adapted  to  this  service  as  the  motor  is 
usually  run  at  constant  speed  and  the  dies  clutched  in 
and  out  as  desired.  An  exception  to  the  above  is  the 
trolley  bench,  especially  on  figure  eight  or  other  than 
round  or  grooved  wire  as,  on  special  shapes,  it  is  de- 
sirable to  start  and  accelerate  slowly  so  that  each  block 
may  be  rigidly  inspected.  Therefore  for  this  service 
the  wound  rotor  motor  is  preferable. 

ANNEALING    FURNACE 

The  conveyors  for  drawing  wire  coils  through  the 
annealing  furnace  are  operated  by  five  horse-power  di- 
rect-current adjustable-speed  motors,  having  in  addi- 
tion to  the  shunt  and  commutating-pole  windings,  a 
compensating  winding,  giving  sparkless  commutation 
under  all  conditions.  The  speed  ranges  from  450  to 
1800  r.p.m.,  which  is  varied  by  means  of  shunt  field 
control. 

STRANDING  EQUIPMENT 

The  7  stranding  machines  and  19  stranding  ma- 
chines are  driven  by  15  hp,  500  volt,  direct-current 
shunt  interpole  motors.  The  37  stranding  ma- 
chine is  driven  by  a  440  volt,  720  r.p.m.,  wound  rotor 
motor  as,  on  account  of  the  slow  speed,  an  adjustable 
speed  motor  is  not  required. 

LIGHTING 

The  lighting  is  symmetrically  installed  on  roof 
trusses  which  clear  the  crane  bridge  about  three 
feet.  This  not  only  facilitates  initial  installation, 
but  makes  a  very  convenient  method  of  caring  for 
lamp  renewals  and  periodic  cleaning  of  shades  and 
lamps,  as  work  may  be  done  from  the  crane  bridge. 
The  original  installation  consisted  of  18  inch  flat 
shades  with  750  watt  lamps.  However,  these  were 
later  changed  to  shaped  reflectors  and  500  watt  lamps 
over  the  rolls  and  stranders,  and  300  watt  lamps  for 
general  illumination. 

All  lighting  and  power  feeders  are  lead  covered 
cables  run  under  the  floor  in  fibre  ducts  with  man- 
holes situated  in  desirable  places  for  distribution.  All 
disconnect  switches  ahead  of  the  compensators  and  oil 
switches  are  totally  enclosed  and  the  frames  of  all 
machines  are  well  grounded  to  avoid  any  possibility  of 
accidents. 


lectricd  Cljar  act);  oris  lies  o'i  '^ransmmiaa 

Synciironous  Motors  and  Gon'tciissrs  for  i'ovy-.)f -i'^aotor  (iiiprovoiaeinii; 


WM.  NESBIT 


BEFORE  discussing  the  employment  of  syn- 
chronous machinery  for  improving  the  power- 
factor  of  circuits,  it  may  be  desirable  to  review 
how  a  change  in  power- factor  affects  the  generators 
supplying  the  current. 

Fig.  6i  shows  the  effect  of  in-phase,  lagging  and 
leading  components  of  armature  current  upon  the  field 
strength  of  generators*.  A  single-coil  armature  is  il- 
lustrated as  revolving  between  the  north  and  south 
poles  of  a  bipolar  alternator.  The  coil  is  shown  in 
four  positions  90  degrees  apart,  corresponding  to  one 
complete  revolution  of  the  armature  coil.  The  direc- 
tion of  the  field  flux  is  assumed  to  be  constant  as  in- 
dicated by  the  arrows  on  the  field  poles  of  each  illus- 
tration. In  addition  to  this  field  flux,  when  current 
flows  through  the  armature  coil  another  magnetic  flux 
is  set  up,  magnetizing  the  iron  in  the  armature  in  a  di- 
rection at  right  angles  to  the  plane  of  the  armature  coil. 
This  will  be  referred  to  as  armature  flux. 

This  armature  flux  varies  with  the  armature  cur- 
rent, being  zero  in  a  single-phase  generator  when  no 
armature  current  flows,  and  reaching  a  maximum 
when  full  armature  current  flows.  It  changes  in  direc- 
tion relative  to  the  field  flux  as  the  phase  angle  of  the 
armature  current  changes. 

The  revolving  armature  coil  generates  an  alternat- 
ing voltage  the  graph  of  which  follows  closely  a  sine 
wave,  as  shown  in  Fig.  61.  When  it  occupies  a  verti- 
cal plane  marked  start  no  voltage  is  generated,  for  the 
reason  that  the  instantaneous  travel  of  the  coil,  is 
parallel  with  the  field  flux.**  As  the  coil  moves  for- 
ward in  a  clockwise  direction,  the  field  enclosed  bv 
the  armature  coil  decreases;  at  first  slowly  but  dien 
more  rapidly  until  the  rate  of  change  of  flux  through 
the  coil  becomes  a  maximum  when  the  coil  has  turned 
90  degrees,  at  which  instant  the  voltage  generated  be- 
comes a  maximum.  As  the  horizontal  position  is  passed 
the  voltage  decreases  until  it  again  reaches  zero  when 
the  coil  has  traveled  180  degrees  or  occupies  again  a 
vertical  plane.  As  the  travel  continues  the  voltage 
agiin  starts  to  increase  but  since  the  motion  of  the  coil 

*For  a  more  detailed  discussion  of  this  subject  the  reader 
i^  referred  to  excellent  articles  by  F.  D.  Newbury  in  the 
■^Ilectric  Journal  of  April  1918,  "Armature  Reaction  of  Poly- 
phase Alternators" ;  and  of  July  1918,  "Variation  of  Alternator 
Excitation  with  Load". 

**For  the  sake  of  simplicity  this  and  the  following  state- 
ments are  based  upon  the  assumption  that  armature  reaction 
does  not  shift  the  position  of  the  field  flux.  Actually,  under 
load,  the  armature  reaction  causes  the  position  of  the  field  flux 
to  be  shifted  toward  one  of  the  pole  tips,  so  that  the  position 
of  the  armature  coil  is  not  quite  vertical  at  t*le  instant  of  zero 
voltage  in  the  coil. 


relative  to  the  fixed  magnetic  field  is  reversed  the  volt- 
age in  the  coil  builds  up  in  the  reverse  direction  dur- 
ing the  second  half  of  the  revolution.  When  the  coil 
has  reached  the  two  270  degree  position  the  voltage 
has  again  become  maximum  but  in  the  opposite  direc- 
tion to  that  when  the  coil  occupied  the  position  of 
90  degrees.  When  the  coil  returns  to  its  original  posi- 
tion at  the  start  the  voltage  has  again  dropped  to  zero, 
thus  completing  one  cycle. 

If  the  current  flowing  through  this  armature  coil 
is  in  phase  with  the  voltage,  it  will  produce  cross  mag- 
netization in  the  armature  core,  in  a  vertical  direction, 
as  indicated  by  the  arrows  at  the  90  and  270  degree 
positions.  The  cross  magnetization  neither  opposes 
nor  adds  to  the  field  flux  at  low  loads  and  therefore  has 
comparatively  little  influence  on  the  field  flux.  At 
heavy  loads,  however,  this  cross  magnetization  has  con- 
siderable demagnetizing  effect,  due  to  the  shift  in  ro- 
tor position  resulting  from  the  shifting  of  the  field  flux 
at  heavy  loads. 

If  the  armature  is  carrying  lagging  current,  this 
current  will  tend  to  magnetize  the  armature  core  in 
such  a  direction  as  to  oppose  the  field  flux.  This  ac- 
tion is  shown  by  the  middle  row  of  illustrations  of 
Fig.  61.  Under  these  illustrations  is  shown  a  current 
wave  lagging  90  degrees  representing  the  component 
of  current  required  to  magnetize  transformers,  induc- 
tion motors,  etc.  When  the  lagging  component  of  cur- 
rent reaches  its  maximum  value  the  armature  coil  will 
occupy  a  vertical  position  (position  marked  start,  180 
degrees  and  360  degrees)  and  in  this  position  the  arma- 
ture flux  will  directly  oppose  the  field  flux,  as  indicated 
by  the  arrows.  The  result  is  to  reduce  the  flux  thread- 
ing the  armature  coil  and  thus  cause  a  lowering  of  the 
voltage.  This  lagging  current  encounters  resistance 
and  a  relatively  much  greater  reactance,  each  of  which 
consumes  a  component  of  the  induced  voltage,  as 
shown  in  Fig.  62.  When  the  armature  current  is  lag- 
ging, the  voltage  induced  by  armature  inductance  is  in 
such  a  direction  as  to  subtract  from  the  induced  volt- 
age, and  thus  the  voltage  is  still  further  lowered,  as  a 
result  of  the  armature  self  induction.  In  order  to 
bring  the  voltage  back  to  its  normal  value  it  will  be 
necessary  to  increase  the  field  flux  by  increasing  the 
field  current.  Generators  are  now  usually  designed  of 
sufficient  field  capacity  to  compensate  for  lagging 
loads  of  80  per  cent  power-factor. 

If  the  armature  is  carrj'ing  a  leading  current  this 
leading  component  will  tend  to  magnetize  the  armature 
core  in  such  a   direction   as   to   add   to   the   field   flux. 


366 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  N"o.  8 


This  action  is  shown  by  the  bottom  row  of  illustrations 
of  Fig.  6i.  Under  these  illustrations  is  shown  a  current 
wave  leading  the  voltage  wave  by  90  degrees.  When 
the  leading  component  of  current  reaches  its  maximum 
values,  the  armature  coil  will  again  occupy  vertical 
positions,  but  the  armature  flux  will  add  to  that  of  the 
field  flux,  as  indicated  by  the  arrow.  The  resulting 
flux  threading  the  armature  coil  is  thus  increased  caus- 
ing a  rise  in  voltage.  This  leading  current  flowing 
through  the  generator  armature  encounters  resistance 
and  a  relatively  much  greater  reactance,  each  of  which 
consumes  a  component  of  the  induced  voltage,  as 
shown  in  Fig.  62.     When  the  armature  current  is  lead- 


OROSS  MAQNET12INQ  EFFECT  OF    IN-PHASE  ARMATURE  CURRENT 


Eia  5B  KtS  5S  53 


FIG.  61 — EFFECT  OF  ARMATURE  CURRENT  UPON  FIELD  EXCITATION  OF 
ALTERNATING-CURRENT  GENERATORS 

ing,  the  voltage  induced  by  armature  inductance  is  in 
such  a  direction  as  to  add  to  the  induced  voltage  und 
thus  the  voltage  at  the  alternator  terminals  is  .still 
further  increased  as  the  result  of  armature  self-induc- 
tion. In  order  to  reduce  the  voltage  to  its  normal 
value  it  is  necessary  to  decrease  the  field  flux  by  de- 
creasing the  field  current. 

With  alternators  of  high  reaction  the  magnetizing 
or  de-magnetizing  effect  of  leading  or  lagging  current 
will  be  greater  than  in  cases  where  the  armature  reac- 
tion is  low.  For  instance  if  the  alternator  is  so  de- 
signed that  the  ampere  turns  of  the  armature  at  full 
armature  current  are  small  compared  to  its  field  am- 
pere turns,  the  voltage  of  such  a  machine  would  be  less 
disturbed  with  a  change  in  power-factor  of  the  arma- 


ture current  than  in  an  alternator  having  armature 
ampere  turns  large  compared  with  its  field  ampere 
turns. 

Modern  alternators  are  of  such  design  that  when 
carrj'ing  rated  lagging  current  at  zero  power- factor 
they  require  approximately  200  to  250  percent  of  their 
no-load  field-current  and  when  carrj'ing  rated  leading 
current  at  zero  power-factor  they  require  approximate- 
ly — 15  to  -]-i5  percent  of  their  no-load  field  current. 
Thus  with  lagging  armature  current  the  iron  will  be 
worked  at  a  considerable  higher  point  on  the  satura- 
tion curve  and  the  heating  of  the  field  coils  will  in- 
crease because  of  the  greater  field  current  required. 

The  voltage  diagrams  of  Fig.  62  are  intended  to 
show  only  the  effect  of  armature  resistance  and  arma- 
ture reactance  upon  voltage  variation.     Voltage  regu- 


FIG.   62 — \'ECTORS   ILLUSTRATING  THE   EFFECT   OF  ARMATURE   REACT- 
ANCE AND  RESISTANCE  UPON  THE  TERMINAL  VOLTAGE  FOR  IN-PHASE, 
LEADING  AND  LAGGING  CURRENTS 

lation  is  the  combined  effect  of  armature  impedance 
and  armature  reaction.  Turbogenerators  have,  for 
instance,  very  low  armature  reactance  but  their  arma- 
ture reaction  is  higher,  so  that  the  resulting  voltage 
regulation  may  not  be  materially  different  from  that  of 
a  machine  with  double  the  armature  reactance. 
Under  normal  operation  armature  reaction  is  a  mo'"e 
potent  factor  in  determining  the  characteristics  of  .1 
generator  than  armature  reactance.  In  the  case  of  a 
generator  with  a  short  circuit  ratio  of  unit}',  this  totai 
reactive  effect  may  be  due,  15  percent  to  armature  re- 
actance and  85  percent  to  armature  reaction. 

For  the  case  illustrated  by  V\g.  62  the  field  flux 
corresponds  to  the  induced  voltage  indicated,  but  the 
field  current  does  not.  The  field  current  corresponds 
to  a  value  obtained  by  substituting  the  full  synchron- 
ous impedance  drop  for  that  indicated. 


August,  192 1 


THE   ELECTRIC   JOURNAL 


367 


SYNCHRONOUS  CONDENSERS  AND  PHASE  MODIFIERS 

The  term  "synchronous  condenser"  appHes  to  ri 
synchronous  machine  for  raising  the  power-factor  of 
circuits.  It  is  simply  floated  on  the  circuit  with  its 
fields  over  excited  so  as  to  introduce  into  the  circuit  a 
leading  current.  Such  machines  are  usually  not 
intended  to  carry  a  mechanical  load.  When  this  dou- 
ble duty  is  required  they  are  referred  to  as  synchron- 
ous motors  for  operation  at  leading  power-factor. 
On  long  transmission  circuits,  where  synchronous  con- 
densers are  used  in  parallel  with  the  load  for  varying 
the  power-factor,  thereby  controlling  the  transmission 
voltage,  it  is  sometimes  necessary  to  operate  them  with 
under  excited  fields  at  periods  of  lightloads.  They  are 
then  no  longer  synchronous  condensers  but  strictly 
speaking  become  synchronous  reactors. 

Whether  synchronous  motors  for  operation  at 
leading  power-factor,  synchronous  condensers  or  syn- 
chronous reactors  be  used  they  virtually  do  the  same 
thing,  that  is;  their  function  is  to  change  the  power- 
factor  of  the  load  by  changing  the  phase  angle  between 
the  armature  current  and  the  terminal  voltage.     They 

TABLE  R— SYNCHRONOUS  CONDENSER  LOSSES 


Kv-a 

Loss  (Kw) 

Kv-a 

Loss  (Kw) 

100 

12 

3500 

180 

200 

18 

Sooo 

220 

300 

22 

7500 

320 

500 

32 

lOOOO 

420 

750 

47 

15000 

620 

1000 

55 

20000 

820 

1500 

70 

25000 

1000 

2000 

120 

35000 

1400 

2500 

130 

50000 

2000 

are,  therefore,  sometimes  referred  to  as  "phase  modi- 
fiers." This  latter  name  seems  more  appropriate  when 
the  machine  is  to  be  operated  both  leading  and  lagging, 
as  when  used  for  voltage  control  of  long  transmission 
lines. 

Rating  — ■  Synchronous  condensers  as  regularly 
built  may  be  operated  at  from  30  to  40  percent  of  their 
rating  lagging,  depending  upon  the  individual  design. 
Larger  lagging  loads  result  in  unstable  operation  on 
account  of  the  weakened  field.  Phase  modifiers  can 
be  designed  to  operate  at  full  rating,  both  leading  and 
lagging,  but  they  are  larger,  require  larger  exciters, 
have  a  greater  loss  and  cost  15  to  20  percent  more 
than  standard  condensers. 

Starting — Condensers  are  furnished  with  squir- 
rel-cage damper  windings,  to  prevent  hunting,  which 
also  provides  a  starting  torque  of  approximately  30 
percent  of  normal  running  torque.  They  have  a  pull- 
in  torque  of  around  15  percent  of  running  torque. 
The  line  current  at  starting  varies  from  50  to  100  per- 
cent of  normal.  The  larger  units  are  sometimes 
equipped  for  forced  oil  lubrication,  which  raises  the 
rotor  sufficiently  to  permit  of  oil  entering  the  bearing, 
thus  reducing  the  starting  current. 


Mechanical  Load — Synchronous  condensers  are 
generally  built  for  high  speeds  and  equipped  with 
shafts  of  small  diameter.  If  they  are  to  be  used  to 
transmit  some  mechanical  power  it  may  be  necessary 
to  equip  them  with  larger  shafts  and  bearings,  particu- 
larly if  belted  rather  than  direct  connected.  If  a 
phase  modifier  is  to  furnish  mechanical  energy  and  at 
the  same  time  to  operate  lagging  at  times  of  light  load 
for  the  purpose  of  holding  down  the  voltage  on  an  un- 
loaded transmission  line  there  may  be  danger  of  the 
machine  falling  out  of  step,  if  a  heavy  mechanical  load 
occurs  when  the  machine  is  operating  with  a  weak 
field. 

Losses — At  rated  full  load  leading  power-factor 
the  total  losses,  including  those  of  the  exciter,  will  vary 
from  approximately  12  percent  for  the  smallest  capaci- 
ty to  approximately  four  percent  for  the  larger  capaci- 
ty 60  cycle  synchronous  condensers.     The  approximate 


\ 

// 

\ 

% 

—M- 

i 

"= 

I 

^j 

% 

/ 

/I 

?\e. 

\/ 

/  FULL  LOAD 

T 

/     CURRENT 

1 

IOO%P 

/ 

300 

\ 

/ 

\ 

/ 

100 

\ 

1  / 

/ 

IOO»f 

V 

2 

6             6 

0             7 

5             IC 

0            1 

6            16 

0            i  76           20 

FIELD  AMPERES 

FIG.  63 — V-CURVES  OF  A  PHASE  MODIFIER 

values  given  in  Table  R  may  be  of  service  for  prelimin- 
ary purposes. 

"V"  Curves — The  familiar  V  curves  shown  in 
Fig.  63  serve  to  give  some  idea  of  the  variation  in  field 
current  for  a  certain  phase  modifier  when  operating 
between  full  load  lagging  and  full  load  leading  kv-a.* 
For  this  particular  machine  the  excitation  must  be  in- 
creased from  112  amperes  at  no  load  minimum  input 
or  unity  power-factor  to  155  amperes  at  full  kv-a  out- 
put leading  or  a  range  of  1.4  to  i  in.  field  excitation. 
For  operation  between  full  lagging  and  full  leading, 
with  no  mechanical  work  done,  the  range  of  excitation 
is  from  67  to  155  or  2.3  to  i. 

Generators  as  Condensers — Ordinary  alternators 
may  be  employed  as  synchronous  condensers  or  syn- 
chronous motors  by  making  proper  changes  in  their 
field  poles  and  windings  to   render  them   self-starting 


*These  curves  have  been  reproduced  from  H.  B.  Dwight's 
book  "Constant  Voltage  Transmission", 


368 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


and  safely  insulated  against  voltages  induced  in  the 
field  when  starting. 

Where  transmission  lines  feed  into  a  city  net  work 
and  a  steam  turbine  generator  station  is  available  theSi^ 
generating  units  can  serve  as  synchronous  condensers 
by  supplying  just  enough  steam  to  supply  their  losses 
and  keep  the  turbine  cool.  When  operated  in  this  way 
they  make  a  reliable  standby  to  take  the  unportant  load 
quickly  in  case  of  trouble  on  a  transmissfon  line. 

Location  for  Condensers — The  nearer  the  center 
of  load  that  the  improvement  in  power-factor  is  made 
the  better,  as  thereby  the  greatest  gain  in  regulation, 
greatest  saving  in  conductors  and  apparatus  are  made 
since  distribution  lines,  transformers,  transmission 
lines  and  generators  will  all  be  benefited. 

How  High  to  Raise  the  Power-Factor — Theoreti- 
cally for  most  efficient  results  the  system  power 
factor  should  approach  unity.  The  cost  of  synchron- 
ous apparatus  having  sufficient  leading  current  capaci- 
ty to  raise  the  power-factor  to  unity  increases  5o 
rapidly  as  unity  is  approached,  as  to  make  it  unecono- 
mical to  carry  the  power-factor  correction  too  high.. 
Not  only  the  cost  but  also  the  power  loss  chargeable  '<o 
power-factor  improvement  mounts  rapidly  as  higher 
power-factors  are  reached.  This  is  for  the  reason  that 
the  reactive  kv-a  in  the  load  corresponding  to  each  per- 
cent change  in  power-factor  is  a  maximum  for  power- 
factors  near  unity.  It  usually  works  out  that  it 
doesn't  pay  to  raise  the  power  factor  above  90  to  95 
percent,  except  in  cases  where  the  condenser  is  used 
for  voltage  control,  rather  than  power-factor  improve- 
ment. 

DETERMINING    THE    CAPACITY   OF    SYNCHRONOUS    MOTORS 
AND  CONDENSERS  FOR  POWER-FACTOR  IMPROVEMENT 

A  very  simple  and  practical  method  for  determining 
the  capacity  of  synchronous  condensers  to  improve  the 
power-factor  is  by  aid  of  cross  section  paper.  A  very 
desirable  paper  is  ruled  in  inch  squares,  sub-ruled  mto 
10  equal  divisions,  ^^'ith  such  paper,  no  other  equip- 
ment is  required. 

With  a  vector  diagram  it  is  astonishing  how  easy- 
it  is  to  demonstrate  on  cross  section  paper,  the  effect 
of  any  change  in  the  circuit.  A  few  typical  cases  are 
indicated  in  Fig.  64.  These  diagrams  are  all  based  up- 
on an  original  circuit  of  3000  kv-a  at  70  percent  power- 
factor  lagging,  shown  by  (i).  It  is  laid  off  on  the 
cross  section  paper  as  follows.  The  power  of  the  cir- 
cuit is  70  percent  of  3000  or  2100  kw,  which  is  laid  off 
on  line  AB,  by  counting  21  sub-divisions,  making 
each  sub-division  represent  100  kw  or  100  kv-a.  Now 
lay  a  strip  of  blank  paper  over  the  cross  section  paper 
and  make  two  marks  on  one  edge  spaced  30  sub-divi- 
sions apart.  This  will  then  be  the  length  of  the  line  AC. 
This  blank  sheet  is  now  laid  over  the  cross  eection 
paper  with  one  of  the  marks  at  the  edge  held  at  the 
point  A.  The  other  end  of  tJie  paper  is  moved  down- 
ward until  the  second  mark  faUs  directly  below  flie 
point  'B    thus   locating  point  C.     The  length   of   the 


line  BC  represents  the  lagging  reactive  kv-a  in  the  cir- 
cuit, in  this  case  2140  kv-a. 

Diagram  (2)  shows  the  effect  of  adding  a  1500 
kv-a  synchronous  condenser  to  the  original  circuit. 
The  full  load  loss  of  this  condenser  is  assumed  as  70 
kw.  The  resulting  kv-a  and  power- factor  are  de- 
termined as  follows:  Starting  from  the  point  C  trace 
to  the  right  a  line  0.7  of  a  division  long.  This  is 
parallel  to  the  line  AB  for  the  reason  that  it  is  true 
power,  so  that  there  is  now  2170  kw  true  energy.  The 
black  triangle  represents  the  condenser,  the  line  CD, 
15  divisions  long,  representing  the  rating  of  the  con- 
denser. In  this  case,  however,  the  vertical  line  is 
traced  upward  in  place  of  downward,  because  the  con- 
denser kv-a  is  leading.  This  condenser  results  in  de- 
creasing the  load  from  3000  kv-a  at  70  percent  power- 
factor  to  2275  kv-a  at  95.4  percent  power-factor.  The 
line  AD  represents  in  magnitude  and  direction,  the  re- 
sulting kv-a  in  this  circuit.  The  power-iractor  of  the 
resulting  circuit  is  the  ratio  of  the  true  energy  in  kw  to 
the  kv-a  or  95.4  percent,  in  this  case,  bince  the  line 
AD  lays  below  the  line  AB,  that  is  in  the  lagging  direc- 
tion, the  power-factor  is  lagging. 

Diagram  (3)  is  the  same  as  (2)  except  that  the 
condenser  is  larger,  being  just  large  enough  fo  neu- 
tralize all  of  the  lagging  component  of  the  load,  result- 
ing in  a  final  load  of  2215  kw  at  100  percent  power-fac- 
tor. Diagram  (4)  is  similar  to  (3)  except  that  a 
still  larger  condenser  is  shown.  This  condenser  not 
only  neutralizes  all  of  the  lagging  kv-a  of  the  load  but 
in  addition  introduces  sufficient  leading  kv-a  into  the 
circuit  to  give  a  leading  resultant  power-factor  of  94 
percent  with  an  increase  in  kv-a  of  the  resulting  cir- 
cuit from  2215  of  (3)  to  2400  kv-a  of  (4). 

Diagram  (5)  illustrates  the  addition  to  the  original 
circuit  of  a  100  percent  power-factor  synchronous 
motor  of  600  hp.  rating  As  this  motor  has  no  leading 
or  lagging  component,  there  is  no  vertical  projection. 
The  power-factor  of  the  circuit  is  raised  from  70  to 
yy  percent  as  the  result  of  the  addition  of  500  kw  true 
power  (load  plus  loss  in  motor)  to  the  circuit.  A  re- 
sistance load  would  have  this  same  effect. 

Diagram  (6)  shows  a  450  kw  (600  hp.)  syn- 
chronous motor  of  625  kv-a  input  at  80  percent  lead- 
ing power-factor  added  to  the  original  circuit.  The 
input  to  this  motor  (including  losses)  is  assumed  to  be 
500  kw.  The  resulting  load  for  the  circuit  is  3150 
kv-a  at  82.5  percent  lagging  power-factor. 

The  Diagram  (7)  shows  an  850  kw,  (1140  hp.) 
synchronous  motor  generator  of  1666  kv-a  input  at  60 
percent  power-factor  leading  added  to  the  original  cir- 
cuit. This  gives  a  resulting  load  of  3200  kv-a  at  96.9 
percent  lagging  power-factor. 

♦  Diagram  (8)  shows  the   addition    to    the    original 
circuit  of  the  following  loads,  including  losses. 

A    550  kw  synchronous  converter  at  100  percent  power- 
factor. 
A    650    kw    induction    motor    at    70    percent    lagging 
powor-factor. 
A    500  kw  synchronous  mote  r. 


August,  1 92 1 


THE   ELECTRIC   JOURNAL 


369 


The  resultant  load  of  this  circuit  is  3800  kw,  and 
if  a  power-factor  of  95  percent  lagging  is  desired  the 
total  kv-a  will  be  4000.  The  line  AD  may  be  located 
by  a  piece  of  marked  paper  and  the  capacity  of  the 
necessary    synchronous    motor     scaled     off.     This    is 


The  Circle  Diagram — The  circle  diagram  in  Fig.  65 
shows  the  fundamental  relations  between  true  kw,  reac- 
tive kv-a  and  apparent  kv-a  corresponding  to  different 
power-factors,  the  values  upon  the  chart  being  read  to 
any  desired  scale  to  suit  the  numerical  values  of  the 


found  to  be  1650  kv-a  at  30.3  percent  power-factor.         problem  under  consideration.     This    diagram   is   suffi- 


Fig.  64 — EXAMPLES  IW  POWER-FACTOB  IMPROVEMENT 


370 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


ciently  accurate  for  ordinary  power-factor  problems. 
In  place  of  drawing  out  the  vector  diagrams  as  just 
explained  they  are  traced  out  with  a  pin  point  on  the 
circle  diagram. 

Assume  again  a  load  of  2100  kw  at  70  percent 
power-factor  lagging,  and  that  the  power-factor  is  to 
be  raised  to  95.4  percent  as  in  (2)  of  Fig.  64,  and  that 
the  loss  in  the  condenser  necessary  to  accomplish  this 
is  again  taken  as  70  kw.  The  capacity  of  the  syn- 
chronous condenser  may  be  traced  on  the  circle  dia- 
gram as  follows:  From  the  true  power  load  of  2100 
kw  (top   horizontal  line)    follow   vertically   downward 


of  the  condenser  would  be  the  hypotenuse  rather  than 
the  vertical  projection.  The  error  in  assuming  the 
vertical  projection  as  the  rating  of  the  condenser  is 
negligible  unless  the  condenser  furnishes  mechanical 
power,  in  which  case  the  hypotenuse  should  be  marked" 
on  a  separate  strip  of  paper  and  its  length  determined 
from  the  kv-a  scale. 

ADVANTAGE    OF    HIGH    POWER-FACTOR 

Less  Capacity  Installed — Low  power-factors  de- 
mand larger  generators,  exciters,  transformers,  switch- 
ing equipment  and  conductors.     Loads  of  70  percent 


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FIG.  65 — RELATION  BETWEEN  ENERGY  LOAD,  APPARENT  LOAD  AND  REACTIVE  KV-A  FOR  DIFFERENT  POWER  FACTORS 


until  the  diagonal  line  representing  70  percent  power- 
factor  is  reached.  This  is  opposite  2140  kv-a  reactive 
component.  From  the  point  thus  obtained,  go  hori- 
zontally to  the  right  a  distance  representing  70  kw 
power.  From  this  point  go  vertically  upward  until 
the  diagonal  line  representing  95.4  percent  power-fac- 
tor is  reached.  Then  read  the  amount  of  reactive  kv-a 
(640)  corresponding  to  this  last  point.  The  original 
lagging  component  of  2140—640^1500  kv-a  which  is 
approximately  the  capacity  of  the  condenser  necessary 
to  accomplish  the  above  results.     Actually  the  rating 


power-factor  demand  equipment  of  28  percent  greater 
capacity  than  would  be  required  if  the  power-factor 
were  90  percent.  The  cost  of  apparatus  for  opera- 
tion at  70  percent  power-factor  would  be  approxi- 
mately 15  percent  greater  than  the  cost  of  similar  ap- 
paratus for  90  percent  power-factor  operation,  since 
the  capacity  of  apparatus  to  supply  a  certain  amount 
of  energy  is  inversely  proportional  to  the  power-factor. 
Higher  Efficiency— Assume  that  the  power-factor 
of  a  1000  kv-a  (700  kw  at  70  percent  power- factor) 
transmission  circuit  is  raised  to  90  percent.  As  the  cop- 


August,  1921 


THE    ELECTRIC   JOURNAL 


371 


per  loss  varies  as  the  square  of  the  current,  raising  the 
power-factor  reduces  the  copper  loss  approximately 
40  percent.  If  we  assume  an  efficiency  for  the  genera- 
tor of  93  percent  (one  percent  copper  loss)  ;  for  com- 
bined raising  and  lowering  transformers  94  percent 
(three  percent  copper  loss)  and  for  the  transmission 
line  92  percent,  the  saving  in  copper  loss  correspond- 
ing to  90  percent  power-factor  operation  would  be  as 
follows : 

Generators 0.4  percent 

Transformers 1.2  percent 

Transmission  line  ....  3.2  percent 

Total 4.8  percent  or  approximately  33  kw. 

To  raise  the  power- factor  to  90  percent  would  re- 
quire a  synchronous  condenser  of  375  kv-a  capacity. 
This  size  condenser  would  have  a  total  loss  of  about 
30  kw,  resulting  in  a  net  gain  in  loss  reduction  of 
three  kw.  Against  this  gain  would  be  chargeable,  the 
interest  and  depreciation  of  the  condenser  cost  with  its 
accessories,  also  any  cost  of  attendance  which  there 
might  be  in  connection  with  its  operation.  It  is  evi- 
dent that  in  this  case  it  would  not  pay  to  install  a  con- 
denser if  increased  efficiency  were  the  only  motive. 

TABLE  S— COST  OF  POWER-FACTOR  CORRECTION 
WITH  SYNCHRONOUS  MOTORS 


Chargeable  to 

Syn.  Motor 
Kv-a 

Motor  W 

Ml  Furnish 

Power-Factor  Correction 

Mech. 

Leading 

Loss 

Difference 

Kw 

Kv-a 

Kw 

in  Price 

140 

100 

100 

1.6 

$500.00 

280 

200 

200 

2.5 

500.00 

420 

300 

300 

50 

500.00 

700 

500 

500 

8.0 

800.00 

1050 

750 

750 

9.0 

1000.00 

1400 

1000 

1000 

14.0 

1200.00 

The  improvement  in  power-factor  can  be  more 
cheaply  and  efficiently  obtained  by  the  installation  of 
one  or  more  synchronous  motors  designed  for  opera- 
tion at  leading  power-factor.  Sufficient  capacity  of 
these  will  give,  in  addition  to  mechanical  load,  suffi- 
cient leading  current  to  raise  the  power-factor  to  90 
percent.  The  extra  expense  and  increased  loss  of 
synchronous  motors  enough  larger  to  furnish  the  nec- 
essary leading  component  for  power-factor  correction 
is  very  small.  Table  S  gives  in  a  very  approximate 
way,  some  idea  of  the  amount  of  loss  and  proportional 
cost  of  synchronous  motors  chargeable  to  power-factor 
improvement  when  delivering  both  mechanical  power 
and  leading  current. 

Thus  if  a  synchronous  condenser  is  used  on  the 
above  circuit  there  is  a  loss  of  30  kw,  chargeable  to 
power-factor  improvement,  whereas  if  a  synchronous 
motor  of  sufficient  capacity  (530  kv-a)  to  give  375  kw 
mechanical  work  and  at  the  same  time  the  necessary 
375  kv-a  leading  current  for  power-factor  improve- 
ment, the  extra  loss  chargeable  to  power-factor  im- 
provement would  be  something  like  six  kw.  The  in- 
•creased  cost  of  a  synchronous  motor  to  furnish  375 
kv-a  leading  current  in  addition  to  375  kw  power 
would  be  about  $600  whereas  the  cost  of  a  375  kv-a 


condenser  would  be  in  the  neighborhood  of  $4000. 
Varying  costs  and  designs  make  cost  and  loss  values 
unreliable.  They  are  given  here  only  to  illustrate  the 
points  which  should  be  considered  when  considering 
synchronous  motors  vs  synchronous  condensers. 

Improved  Voltage  Regulation — The  voltage  drop 
under  load  for  generators,  transformers  and  trans- 
mission lines  rapidly  increases  as  the  povv^er-factor  goes 
down.  Table  T  gives  an  idea  of  the  variation  in  volt- 
age drop  corresponding  to  various  power- factors  at  60 
cycles. 

Automatic  voltage  regulation  may  be  used  to  hold 
the  voltage  constant  at  the  generators  or  at  some  other 
point,  but  it  cannot  prevent  voltage  changes  at  all 
points  of  the  system. 

Increased  Plant  Capacity — The  earlier  alternators 
were  designed  for  operation  at  100  percent  power-fac- 
tor with  prime  movers,  boilers,  etc.  installed  on  the 
same  basis.  Increasing  induction  motor  loads  have 
resulted  in  power-factors  of  70  and  80  percent.  As  a 
result,  some  of  the  older  generating  stations  are  being 
operated  with  prime  movers,  boilers  etc.  underloaded 
because  the  100  percent  power-factor  generators  which 

TABLE  T— EFFECT  OF  POWER-FACTOR  ON  VOLTAGE 
DROP 


Percent  Power-Factor.          100 

90 

80 

70 

- 
5-5 

15-2 

Generators  *( older  design) 
Transformers 
Transmission  line 

8.0 
1.2 
7-9 

1     25.0 
4.1           4-9 
13.0          14.2 

they  drive  limit  the  amount  of  power  that  can  be  gen- 
erated without  endangering  the  generator  windings. 
This  condition  some  times  makes  it  necessary  to  oper- 
ate three  units,  where  two  might  be  sufficient  to  carry 
the  load  at  unity  power-factor.  The  shutting  down  of 
?.  unit  would  result  in  a  considerable  saving  in  steam 
consumption.  A  recent  case  caine  up  of  a  transmis- 
sion line  30  miles  long,  fed  at  each  end  by  a  small  gen- 
erating station.  On  account  of  heavy  line  drop  it  was 
necessary  to  operate  both  stations  to  furnish  the  com- 
paratively light  night  load.  Investigation  developed 
that  by  installing  a  synchronous  condenser  at  one  of 
these  terminal  stations  for  reducing  the  voltage  drop 
in  the  line,  one  generating  station  could  be  shut  down 
during  the  night,  thereby  resulting  in  a  very  large 
annual  saving  in  coal  and  labor  bills. 

A  station  may  have  some  generating  units  de- 
signed for  100  percent  power-factor  and  other  units 
designed  for  80  percent  power-factor;  or  again,  where 
two  generating  stations  feed  into  the  same  transmission 
system,  one  may  have  100  percent  power-factor  gen- 
erating units  and  the  other  80  percent  power-factor 


*The  present-day  design  of  maximum  rated  generators  with 
a  short-circuit  ratio  of  about  unity  will  barely  circulate  full- 
load  current  with  normal  no-load  excitation.  Under  such  con- 
ditions the  terminal  voltage  would  be  practically  zero  regardless 
of  the  power-factor. 


372 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


generating  units.  In  such  cases,  the  field  strength  of 
the  generators  may  be  so  adjusted  as  to  cause  the  80 
percent  power-factor  units  to  take  all  the  lagging  cur- 
rent, thus  permitting  the  100  percent  power-factor 
units  to  be  loaded  to  their  full  kw  rating. 

BEHAVIOR  OF  A.   C.   GENERATORS  WHEN   CHARGING  A 
TRANSMISSION   LINE* 

It  has  been  shown  above  how  leading  armature 
current,  by  increasing  the  field  strength,  causes  an  in- 
crease in  the  voltage  induced  in  the  armature  of  an 
alternator  and  consequently  an  increase  in  its  terminal 
voltage.  It  was  also  shown  that  the  terminal  voltage 
is  further  increased  as  result  of  the  voltage  due  to 
self  induction  adding  vectorially  to  the  voltage  induced 
in  the  armature. 

If  an  alternator  with  its  fields  open  is  switched 
onto  a  dead  transmission  line  having  certain  electrical 
characteristics,  it  will  become  self  exciting,  provided 
there  is  sufficient  residual  magnetism  present  to  start 
the  phenomenon.  In  such  case,  the  residual  magnet- 
ism in  the  fields  of  the  generator  will  cause  a  low  volt- 
age to  be  generated  which  will  cause  a  leading  line 
charging  current  to  flow  through  the  armature.  This 
leading  current  will  increase  the  field  flux  which  in 
turn  will  increase  the  voltage,  causing  still  more  charg- 
ing current  to  flow,  which  in  turn  will  still  further  in- 
crease the  line  voltage.  This  building  up  will  continue 
until  stopped  by  saturation  of  the  generator  fields. 
This  is  the  point  of  stable  operation.  Whether  or  not 
a  particular  generator  becomes  self  exciting  when 
placed  upon  a  dead  transmission  line  depends  upon  the 
relative  slope  of  the  generator  and  line  characteristics. 

In  Fig.  66  are  shown  two  curves  for  a  single 
45  000  kv-a,  1 1  000  volt  generator,  the  charging  current 
of  the  transmission  line  being  plotted  against  genera- 
tor terminal  voltage.  One  curve  corresponds  to  zero 
excitation,  the  other  curve  to  26.6  percent  of  normal 
excitation.  A  similar  pair  of  curves  correspond  to 
two  duplicate  generators  in  parallel**.  The  straight 
line  representing  the  volt-ampere  characteristics  of  the 
transmission  line  fed  by  these  generators  corresponds 
to  a  220  kv,  60  cycle,  three-phase  transmission  cir- 
cuit, 225  miles  long,  requiring  69  000  kv-a  to  charge  it 
with  the  line  open  at  the  receiving  end. 

The  volt-ampere  charging  characteristic  of  a 
transmission  line  is  a  straight  line,  that  is,  the  charg- 
ing current  is  directly  proportional  to  the  line  voltage. 
On  the  other  hand  the  exciting  volt-ampere  character- 
istic for  the  armature  has  the  general  slope  of  an 
ordinary  saturation  curve. 


_*For  a  more  detailed  discussion  of  this  subject  see  the  fol- 
lowing articles : — "Characteristics  of  Alternators  when  Excited 
by  Armature  Currents"  by  F.  T.  Hague,  in  the  Journal  for  Aug. 
1915;  "The  Behavior  of  Alternators  with  Zero  Power- Factor 
Leading  Current"  by  F.  D.  Newbury,  in  the  Joltrnal  for  Sept. 
1918;  "The  Behavior  of  A.  C.  Generators  when  Charging  a 
Transmission  Line"  by  W.  O.  Morris,  in  the  General  Electric 
Revieiv  for  Feb.  1920. 

**It  is  assumed  that  with  the  assumed  field  current  such 
generators  can  be  synchronized  and  held  together  during  the 
process  of  charging  the  line. 


If  the  alternator  characteristic  lie  above  the  line 
characteristic  at  a  point  corresponding  to  a  certain 
charging  current  the  leading  charging  current  will 
cause  a  higher  armature  terminal  voltage  than  is  re- 
quired to  produce  that  current  on  the  line.  As  a  re- 
sult the  current  and  voltage  will  continue  to  rise  until, 
on  account  of  saturation,  the  alternator  characteristic 
falls  until  it  crosses  the  line  characteristic.  At  this 
point  the  voltage  of  the  generator  and  that  of  the  line 
are  the  same  for  the  corresponding  current.  If  on  the 
other  hand  the  alternator  characteristic  falls  below  the 
line  characteristic  the  alternator  will  not  build  up  with- 
out permanent  excitation. 

As  stated  previously,  whether  or  not  a  generator 
becomes  self-exciting  when  connected  to  a  dead  trans- 
mission line  depends  upon  the  relative  slopes  of  gener- 
ator and  transmission  line  characteristics.  The  rela- 
tive slopes  of  these  curves  depend  upon: — 
a — The  magnitude  of  the  line  charging  current. 
h — The  rating  of  the  generators  compared  to  the  full  voltage 

charging  kr\'-a  of  the  line. 
c — The  armature  reaction.  High  armature  reaction,  (that  is 
low  short-circuit  ratio)  favors  self -excitation  of  the  gener- 
ators. 
d — -The  armature  reactance.  High  armature  reactance  also 
favors  self -excitation  of  the  generators. 

Methods  of  Exciting  Transmission  Lines — If  the 
relative  characteristics  of  an  alternator  and  line  are 
such  as  to  cause  the  alternator  to  be  self -exciting,  this 
condition  may  be  overcome  by  employing  two  or  more 


)0  7000  3000  4000  BOO 

CHARGING  CURRENT  OF  LINE 
(AMPERES  PER  GENERATOR  TERMINAL) 


FIG.  66— VOLT  AMPERE  CHARACTERISTICS  OF  ONE  45  000  KV-A,   1 1  000 

VOLT  generator;   two  DUPLICATE  45  000  KV-A  GENERATORS;  AND  A 

THREE-PHASE,  SINGLE-aRCUIT,  220  KV  TRANSMISSION  UNE 

alternators  (provided  they  are  available  for  this  pur- 
pose) to  charge  the  transmission  line.  The  combined 
characteristics  of  two  or  more  alternators  may  be  such 
as  to  fall  under  the  line  characteristic,  in  which  case 
the  alternator  will  not  be  self -exciting.  In  such  case, 
the  alternators  could  be  brought  up  to  normal  speed, 
and  given  sufficient  field  charge  to  enable  them  to  be 


August,  1921 


THE   ELECTRIC   JOURNAL 


373 


synchronized  and  held  in  step,  after  which  they  could 
be  connected  to  the  dead  transmission  line  and  their 
voltage  raised  to  normal. 

Generators  as  normally  designed  will  carry  ap- 
proximately 40  percent  of  their  rated  current  at  zero 
leading  power-factor.  If  more  than  this  current  is 
demanded  of  them  they  are  likely  to  become  unstable 
in  operation.  By  modifying  the  design  of  normal 
alternators  so  as  to  give  low  armature  reaction,  they 
may  be  made  to  carry  a  greater  percentage  of  leading 
current.     If  the  special  design  is  such  that  with  zero 

TABLE  U-INSTALLATIONS  OF  LARGE  PHASE   MODIFIERS 
By  American  Manufacturers 


(1921) 


Kv-a 

p.P.M. 

Volts 

Cycles 

No.  of 
Units 

Pate  of 
Order 

NASO:  AKD  LOCATION 

30  000 

600 

6600 

50 

1 

1919 

So.  Cal.  Ed.  Co.,  Los  Angeles,  Cal. 

20  000 

600 

H  000 

60 

2 

1921 

Pacific  Gas  &  Elec. 

15  000 

375 

6600 

50 

1912 

Southern  Cal.  Ed.  Co.,  Los  Ang.,   Cal. 

15  000 

375 

6600 

50 

1 

1912 

Pacific  Lt.   &  Pr.  Co. 

12  500 

500 

22  000 

50 

2 

1918 

Andhra  Valley,  India 

7500 

400 

6600 

60 

2 

1913 

Utali  Pr.  &  Lt.  Co.,   Salt  Lake,  Utah 

7500 

400 

6600 

60 

2 

1916 

Canton  El.  Co.,   Canton,  Ohio 

7500 

600 

13  800 

60 

1 

1917 

Blackstone  Valley  Gas  &  Elec.  Co.,  Pawtucket,  R. 

I. 

7500 

600 

13  800 

60 

1 

1917 

New  England  Pr.   Co.,  Worcester,   Mass. 

7500 

720 

13  800 

60 

1 

1918 

New  England  Pr.  Co.,  Fitchburg,  Mass. 

7500 

800 

11  500 

40 

1 

1918 

Adirondack  El.  Pwr.  Corp.,  Watervliet,   New  York 

7500 

750 

11  000 

50 

1 

1919 

Energia    Eloctrica   de    Cataluna,    Barcelona,    Spain 

7500 

600 

11  000 

60 

1 

1920 

Duquesne  Light  Co. 

7500 

600 

1200 

60 

2 

1918 

J.   G.   White,   Engineers 

7500 

600 

11000 

60 

1 

1918 

Duquesne  Light  Co. 

7500 

600 

11  000 

60 

1 

1916 

Duquesne  Light  Co. 

7500 

600 

11  000 

60 

2 

1917 

Duquesne  Light  Co. 

6500 

750 

2200 

50 

1 

1917 

Shanghai  Municipal  Council,   Shanghai,   China 

6000 

500 

16  500 

50 

1 

1914 

So.  Cal.  Ed.  Co.,  Los  Angeles,  Cal. 

5000 

600 

7200 

60 

1 

1916 

Pac.  Pwr.  &  Lt.,  Kennewick,  Wash. 

5000 

500 

6600 

50 

2 

1915 

Tata  Hydro  El.  Pr.  &  S.  Co.,   India 

5000 

750 

6600 

50 

3 

1917 

Ebro  Irrigation  &  Pr.  Co.,  Barcelona,   Spain 

5000 

750 

11  500 

50 

1 

1919 

Societa   Lombarda  Distrihuziona   Energia   Elettrica 

,    Italy 

5000 

600 

2300 

60 

1 

1918 

Turnbull  Steel  Co.,  Warren,  Ohio 

5000 

720 

2300/ 
4000 

60 

1921 

Public  Service  of  N.  III. 

5000 

720 

11  000 

60 

1 

1921 

Takata  &  Co..  Japan. 

5000 

600 

13  200 

60 

1 

1919 

Conn.  Lt.  &  Pr.  Co. 

voltage  field  excitation  when  carrying  half  the  line 
charging  kv-a,  the  armature  voltage  will  not  exceed  yo 
percent  of  normal,  this  reduced  voltage  will  result  in 
a  line  charging  kv-a  of  half  of  normal  value.  Spe- 
cially designed  alternators  usually  result  in  larger  and 
more  costly  machines  and  the  gain  resulting  in  the  spe- 
cial design  is  usually  not  sufficient  to  warrant  the  extra 
cost. 

If  a  single  generator  with  its  field  circuit  open 
were  connected  to  a  dead  transmission  circuit  such  as 
the  one  whose  volt-ampere  characteristics  are  shown  in 


Fig.  66,  and  there  were  sufficient  residual  magnetism 
to  start  the  phenomenon,  the  generator  voltage  would 
rise  to  approximately  double  normal  value  before  the 
point    of    staple    operation    is    reached.      If,    however, 
two  generators  having  26.6  percent  of  normal  excita- 
tion were  paralleled  and  connected  to  this  circuit,  a 
point    of    staple    operation    would    be    reached    at    a 
terminal     voltage     of     approximately     15  500     volts. 
Actually  stable  operation  would  be  reached  at  a  some- 
what less  terminal  voltage  for  the  reason  that  the  line 
would  probably  not  be  open  at  the  receiving  end,  but 
would    probably    have    the 
lowering    transformers    con- 
nected to  it.     In  such  case 
the    magnetizing    current 
required  for  lowering  trans- 
formers   would    lower   the 
receiving    end     voltage,    re- 
sulting in  less  line  charging 
current. 

In  either  case  the 
curves  of  Fig.  66  show  that 
either  more  than  two  gen- 
erators will  be  required  to 
charge  the  line  when  un- 
loaded, or  some  other  meth- 
od of  charging  must  be  re- 
sorted to.  Reactance  coils 
could  be  used  at  the  receiv- 
ing end  to  furnish  lagging 
current  for  neutralizing  some 
of  the  line  charging  cur- 
rent, but  there  might  be  difficulty  in  removing  these 
from  the  circuit  when  the  line  is  fully  charged.  At 
the  present  time  it  is  expected  that  the  problem  of 
charging  long  transmission  lines  may  usually  be  solved 
by  starting  one  or  more  generators  with  sufficient  field 
strength  to  permit  them  to  be  synchronized  and  held  in 
step.  One  or  more  phase  modifiers  with  under-excited 
fields  may  then  be  connected  to  the  line  at  the  receiving 
end  and  brought  up  to  normal  speed  with  the  genera- 
tors. Such  a  method  of  solving  this  problem  has  been 
employed  by  the  Southern  California  Edison  Company. 


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2000 — Heating  of  Iron  Surrounding  a 
Conductor— When  brought  through 
the  cast  iron  frame  of  an  alternating- 
current  generator  in  individual  holes, 
generator  leads  cause  excessive  heat- 
ing, yet  high  voltage  roof  bushings  are 
constructed  for  currents  of  300  am- 
peres with  cast-iron  base  rings  and 
cast-iron    foundation   rings.     "Crosby" 


cable  clamps  each  consisting  of  a  cast- 
iron  yoke  with  a  wrought  iron  U-bolt 
have  been  successfully  used  to  splice 
transmission  line  and  feeder  cables 
carrying  several  hundred  amperes,  yet 
bus-bar  clamps  for  alternating-current 
work  are  commonly  constructed  with 
one  part  alloy.  At  commercial  fre- 
quencies (i)  what  are  the  permissible 


limits  of  current,  (2)  cross-section  of 
the  surrounding  iron,  and  (3)  near- 
ness to  the  conductor  within  which 
objectionable  heating  will  not  occur 
when  one  or  two  conductors  only  of  a 
three-phase  alternating-current  circuit 
are  surrounded  by  cast  iron  or  struct- 
ural steel?  A.  r.  (mont.) 
Regarding    the    heating    of    iron    parts, 


374 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


each  electrical  application  has  its  own 
problems,  depending  on  the  relative 
arrangement  of  these  parts  and  the  cur- 
rent carrying  conductors.  Therefore, 
no  definite  general  limits  as  to  the  dis- 
tance of  iron  parts  from  conductors, 
cross-section  of  iron  and  magnitude  of 
current  can  be  given.  The  temperature 
rise  of  the  iron  is  directly  proportional 
to  the  iron  loss  and  inversely  propor- 
tional to  the  exposed  surface  to  dissipate 
the  heat  caused  by  this  loss.  Hence,  the 
limiting  amount  of  current  and  nearness 
to  the  iron  depend  on  the  shape  as  well 
as  the  cross-section  of  the  iron.  The 
problem,  therefore,  resolves  itself  into 
the  limiting  or  permissible  llux  densities 
and  frequencies,  which  cause  the  iron 
loss  and  hence  the  heating.  These  will 
be  different  for  each  local  condition. 
For  instance,  in  roof  bushings,  the  iron 
is  a  considerable  distance  from  the  con- 
ductor, on  account  of  the  thick  insula- 
tion between  them,  while  on  bus-bars  the 
clamp  is  placed  directly  around  the  bar. 
Then,  for  the  same  current,  the  dux 
density  in  the  cast-iron  bus-bar  clamp, 
and  hence  the  heating,  will  be  much 
greater  than  in  the  roof  bushing  base 
rings.  In  nearly  all  cases,  the  cast-iron 
bus-bar  clamps  are  either  bolted  with 
brass  bolts,  or  made  of  one  part  alloy, 
whereas,  in  roof  bushings,  the  base  rings 
may  be  made  of  cast-iron  up  to  about 
800  amperes  capacity,  .^bove  this  limit, 
the  base  rings  must  either  be  made  of 
alloy  or  split  in  halves  and  insulating 
material  placed  between  the  halves. 
On  alternating-current  generators,  it  is 
standard  practice  to  bring  all  the  leads 
out  through  the  same  hole  in  the  frame 
to  avoid  heating  of  the  frame.  In  one 
particular  case  of  a  two-phase,  350  kv-a 
vertical  generator,  where  the  leads  were 
brought  out  through  different  holes  in 
the  frame,  the  heating  was  sufficient  to 
warrant  changing  the  leads  so  as  to  have 
their  magnetizing  effect  neutralized. 
The  frame  of  the  machine  was  one  inch 
thick,  and  each  of  the  four  leads  car- 
ried about  1600  amperes.  On  account  of 
•the  high  stresses  to  which  the  windings 
of  turbogenerators  are  subjected  on 
short-circuit,  the  coil  extensions  are  ad- 
ditionally braced  by  means  of  wooden 
blocks  bolted  (through  the  coil  exten- 
sions) to  brackets  on  the  frame.  Dur- 
ing an  impedance  test  on  a  6000  kv-a,  13 
200  volt,  25  cycle  machine,  the  bolts 
holding  these  braces,  which  are  made  of 
iron,  and  are  about  9/16  inches  in  diam- 
eter, and  10  inches  long,  became  so  hot 
that  it  was  necessary  to  shut  the  ma- 
chine down  and  replace  the  iron  bolts  by 
bronze  ones.  Each  armature  coil  car- 
ried approximately  790  amperes,  and  the 
winding  was  so  arranged  that  these  bolts 
were  being  cut  by  a  magnetic  field  pro- 
duced by  the  armature  magnetomotive- 
force  having  a  maximum  value  of  ap- 
pro.ximately  18  000  ampere-turns.  .Al- 
though all  the  bolts  were  under  approxi- 
mately the  same  magnetizing  force,  the 
flux  density,  and  hence  the  heating, 
varied  with  the  relative  position  of  the 
different  bolts  to  other  iron  parts. 
Naturally,  the  bolts  nearest  the  core  of 
the  machine  were  considerably  hotter 
than  the  others.  The  bolts  on  another 
machine  of  similar  contruction,  rated  at 
5000  kv-a,  12  000  volts,  60  cycles,  became 
hot  enough  to  melt  the  paraffine  in  the 
supporting  blocks.  During  a  150  per- 
cent load  short-circuit  on  an  8000  kv-a. 
II  000  volts,  60  cycle  machine,  having  48 


coils,    each   carrying    approximately    700 
amperes,  the  following  temperature  rises 
were  observed  on  the  bolts ;   maximum, 
82.5   degrees   C,   mean,   59.6  degrees   C, 
minimum,  31   degrees  C.     It  was  neces- 
sary to  substitute  bronze  bolts  for  only 
the  first  three  rows  of  bolts  nearest  the 
core   of   the   machine.     On   still   another 
machine,  rated  at  5000  kv-a,  13  200  volts, 
60  cycles,  a  comparative  test  w-as  made 
showing  the  temperature   rises   on  both 
bronze  and  iron  bolts. 
The  resultant  rises  were  as  follows : — 
Bronze  Iron 
Bolts    Bolts 

Max 7.5        18 

Mean     10.7        29.2 

Min M-S        49  o 

On  transformers,  it  has  been  found  that 
approximately  1200  amperes  at  25  cycles 
and  700  amperes  at  60  cycles  is  as  high  a 
current  as  can  be  brought  out  through 
three-inch  holes  in  a  transformer  tank 
top  0.5  inch  thick,  before  injurious  heat- 
ing is  encountered.  The  above  figures, 
of  course,  apply  only  to  specific  in- 
stances, but  may  be  indicative  in  a 
general  way  of  the  limiting  value  of  the 
factors  concerned.  m.  w.  s. 

2001—     P.XRAU-ELING     TRANSFORMERS     — 

Given  one  three-phase,  25  cycle,  12  000 
to  600  volt  transformer  connected  star 
on  the  high-tension  side  and  delta  on 
the  low-tension  side,  and  one  bank  of 
three  single-phase,  25  cycle,  12  000  to 
600  volt  transformers  connected  delta 
on  the  high-tension  side  and  delta  on 
the  low-tension  side,  is  there  any  con- 
venient way  in  which  these  two  sets 
can  be  operated  in  parallel  without  re- 
designing the  coils  of  one  set?  It  will 
be  noted  that  one  set  is  connected 
"star-delta"  and  the  other  set  "delta- 
delta",  with  both  sets  having  the  same 
voltage  ratio.  T.  B.    (oNT.') 

It  is  not  possible  to  connect  these 
banks  in  parallel  without  changing  the 
windings  of  one  of  the  banks.  There  is 
30  degrees  phase  displacement  between  a 
"star-delta"  and  a  "delta-delta"  con- 
nected bank  of  transformers  and  if  con- 
nected in  parallel  a  short-circuit  would 
result.  See  article  on  "Phasing  Out 
High-Tension  Lines"  by  E.  C.  Stone,  in 
the  JoiRXAi.  for  Nov.  1917,  p.  448.    h.  f. 

2002— Turbogenerator     Field     Coils — 
Recently   I   had   occasion   to   cut   two 
coils  out  of  a  turbogenerator  winding. 
The   machine   has   operated    satisfact- 
orily since,  but  I  would  like  to  know 
how  far  I  can  go  without  getting  into 
trouble,  due   to  mi  chanicai   unbalance 
of  the  rotor.     The  coils  cut  out  were 
about    120  geometrical    degrees    apart, 
referred  to  periphery  of  the  stator.  In 
case  vibration  should  set  in.  would  it 
remedy  matters  to  cut  out  another  coil 
so  as  to  have  the  coils  cut  out  120  de- 
grees   apart?     In    case    the    coils    had 
been  about  90  degrees  apart  would  it 
be  satisfactory  to  cut  out  two  more  so 
as   to   establish   a   00   degree   relation- 
ship? C.    n.    M.     (WYO.'l 
The  possibility  of  operating  a  machine 
with    coils    or    parts    of    coils    in    either 
field  or  armature  cut  out  of  circuit  de- 
pends, to  a  large  extent,  on  the  tvpe  of 
connection     in     the     armature    winding. 
Field  coils   should  never  be  rut  out  of 
circuit  if  it  is  possible  to  avoid  it.     This 
is  particularly  the  case  if  the  armature 
windings    are    grouped    in    parallel    cir- 
cuits.    Magnetic  unbalance,  resulting  in 


vibration,  nearly  always  follows  any  dis- 
symmetry in  the  field  exciting  circuit. 
A  coil  could  be  cut  out  of  a  two  pole 
rotor  while  one  coil  could  not  be  cut  out 
of  a  four  pole  rotor  without  causing 
mechanical  unbalance.  Armature  or 
stator  coils,  on  the  other  hand,  can  fre- 
quently be  cut  out  without  causing 
trouble  in  the  so-called  open  type  wind- 
ing. In  the  case  of  the  armature  wind- 
ings, there  is  little  danger  from  me- 
chanical unbalance,  and  the  principle 
requirement  is  that  there  be  no  unbal- 
ance of  voltage  in  a  closed  circuit.  In 
the  open  type  of  winding,  if  the  groups 
in  any  one  phase  are  in  parallel  circuits, 
then  corresponding  coils  in  all  parallel 
circuits  should  be  cut  out  of  the  circuit. 
If  this  precaution  is  followed,  there  is, 
in  general,  little  danger  of  doing  dam- 
age to  the  machine  by  removing  from 
the  circuit  coils  not  in  excess  of  five  per- 
cent of  the  total.  This  limit  is  deter- 
mined by  the  extent  to  which  the  mag- 
netic flux  can  be  increased.  An  open 
winding,  made  unsymmetrical  by  remov- 
ing coils  from  some  phases,  and  not 
others,  causes  unsymmetrical  currents  to 
flow  between  it  and  all  symmetrically 
connected  machines  on  the  same  circuit 
The  result  of  these  currents  is  to  set  up 
eddy  currents  in  the  damper  circuits,  or 
faces,  of  all  machines  on  the  system.  In 
general  these  currents  will  be  too  small 
to  cause  appreciable  heating,  and  there- 
fore, can  be  neglected.  r.  e.  g. 

2003 — Changi.ng  Meter  Dial  Con- 
stants— It  is  not  an  uncommon  thing 
to  patch  up  a  meter  installation  for  a 
short  period  with  a  piece  of  apparatus 
that  is  not  regular,  or  change  a  meter 
from  a  line  of  one  voltage  to  another 
of  a  higher  or  lower  potential.  This 
might  mean  that  a  current  trans- 
former burnt  out  which  had  to  be  re- 
placed with  one  of  a  different  ratio 
until  repairs  could  be  made ;  a  meter 
might  burn  out  and  be  replaced  with 
one  that  was  for  a  different  current 
ratio,  or  a  meter  that  has  been  in  serv- 
ice on  a  2200  volt  circuit  having,  say, 
a  current  ratio  of  400  to  5  and  a  po- 
tential ratio  of  20  to  i  may  be  placed 
in  a  33  000  volt  circuit  having  a  cur- 
rent ratio  of  100-5  and  a  potential 
ratio  of  300  to  i.  In  making  these 
changes  it  is  necessary  to  give  the 
meter  a  new  dial  constant,  and  this  is 
quite  complicated  where  both  current 
and  potential  transformers  ratios  have 
been  changed.  It  is  to  this  end  that  I 
would  like  to  know  what  rule  or 
method  to  use  in  figuring  out  what  the 
new  or  changed  dial  constant  should 
be.  It  is  assumed  that  the  meters  arc 
polyphase  watthour  meters  having  a 
5  ampere  current  and  a  no  volt  poten- 
tial winding.  As  an  example,  what 
would  be  the  new  dial  constant  of  a 
meter  connected  to  a  three-phase, 
33  000  volt  line  with  current  trans- 
former ratio  100  to  5  ampere  and  po- 
tential ratio  of  300  to  i.  This  meter 
had  a  dial  constant  of  10  w-hcn  con- 
nected to  a  three-phase  no  volt  line 
with  a  current  transformer  ratio  of  60 

to    I  W.    H.    H.    (X.    Y.) 

.\  polyphase  watthour  meter  is  usually 
equipped  with  a  register,  the  kw  capacity 

, zX  VyjA     , 

of  which  IS  equal  to    — — where 

r  =  the  rating  of  the  meter  in  volts  and 
A  =  the  rating  of  the  meter  in  amperes 
Thus,    a   5    ampere    100   volt   polyphase 


August,  1921 


THE   ELECTRIC   JOURNAL 


375 


meter  which  is  used  without  current  or 

voltage  transformers  is  equipped  with  a 

/     2X100X5      \  ,,. 

I   kw   counter    \—^^         -j   =:i.  It 

the  same  meter  were  used  with  2000/ lOO 
voltage  transformers  and  50/5  current 
transformers,   a   200  kw   register   would 

u      !       •  u  J  ( -°^  X  50  X  2  \ 

be    furnished.  I  =    200  I 

\  1000  / 

Therefore,  if  the  meter  with  the  one  kw 
counter  were  used  with  2000/100  voltage 
transformers  and  50/5  current  trans- 
formers, the  dial  reading  would  have  to 
be  multiplied  by  200,  which  is  the  pro- 
duct of  the  current  and  voltage  trans- 
former ratios.  The  rule  for  determin- 
ing a  multiplier  or  dial  constant  can  be 
expressed  by  the  following  formula : — 
Nezv  dial  constant  =  A'  X  old  dial  constant. 

Where  K=  Product  of  second    set    of 
transformer  ratios  divided  by  product  of 
first  set  of  transformer  ratios 
This    equation,    applied    to    the    example 
given  in  the  above  question,  gives  a  new 
dial  constant  of  100 
20  X  300 
^  =        60X1  =  '°° 

New  constant  =  K  X  10  =  100  X  10  ^ 
1000.  The  above  equation  applies  to  a 
singlephase  or  polyphase  meter,  a.  r.  r. 

2004 — Current  Transformers  in  Series 
— Is  it  possible  to  operate  current 
transformers  in  series?  If  so,  what 
special  merits  will  be  derived  from 
such  a  connection  P.  j.  v.  s.  (wis.) 

Since  the  load  on  a  current  trans- 
former is  connected  in  series,  an  in- 
crease in  load  means  that  more  voltage 
will  be  required  from  the  current  trans- 
former. This  calls  for  increased  flux  in 
the  iron  and  consequently  increased  ex- 
citing current ;  and  since  it  is  the  excit- 
ing current  which  causes  errors  in  cur- 
rent transformers,  the  greater  the  excit- 
ing current  the  greater  the  error.  There 
is,  therefore,  an  advantage  in  using  two 
similar  current  transformers  in  series  if 
the  secondary  load  is  heavy.  j.  b.  g. 

2005 — Shellac — Is  shellac  purchased 
ready  mixed  as  good  for  electrical  use 
as  that  made  in  the  home  shop  ?  At 
what  temperature  should  an  armature 
be  baked  after  dipping?  What  is  the 
safe  temperature  to  dry  out  moisture 
and  water  after  an  armature  is  wound, 
so  as  not  to  destroy  insulation? 

F.   H.    (W.   VA.) 

There  is  no  reason  why  the  ready 
mi.xed  shellac  varnish  is  not  as  good  for 
electrical  use  as  that  made  in  the  home 
shop.  In  fact,  at  the  present  time,  it  is 
so  difficult  to  get  alcohol  of  the  proper 
degree  of  purity  that  it  is  probably  bet- 
ter to  use  a  ready  mixed  shellac- varnish 
than  to  try  to  buy  the  alcohol  and  gum 
shellac  in  small  quantities,  as  would  be 
necessary  in  a  small  shop.  This  is  be- 
cause varnish  makers  have  enough  de- 
mand for  the  alcohol  to  justify  the 
trouble  necessary  in  obtaining  the 
proper  alcohol  for  making  shellac. 
Owing  to  the  high  cost  of  shellac  gum, 
many  varnish  makers  manufacture  shel- 
lac substitutes,  but  if  the  pure  shellac  is 
requested,  they  will  supply  it,  at  a  higher 
price  than  the  substitute.  The  proper 
temperature  to  dry  out  insulation  is 
slightly  above  the  boiling  point  of  water. 
This  is  also  a  good  temperature  to  use 
for  baking  an  armature  after  dipping. 
The  temperature  should  range  from  100 
to  no  degrees  C.  l.  e.  f. 


2006 —  JNIotok-Generator  for  Railway 
Work — Why  is  an  impedance  coil 
connected  in  series  with  the  commu- 
tating-pole  shunt  resistance  on  a  500 
kw,  600  volt,  720  r.p.m.  motor-gener- 
ator used  for  railway  work,  as  shown 
in  Fig.   (a).  a.  h.  k.   (cal.) 

In  a  commutating-pole  machine,  a 
small  pole  is  placed  between  two  ad- 
jacent main  poles  for  the  purpose  of  set- 
ting up  a  local  magnetic  flux  under 
which  the  armature  coil  is  commutated. 
In  order  to  assist  commutation,  this 
local  flux  must  be  opposite  in  direction 
to  the  interpolar  flux  set  up  by  the  ar- 
mature winding  itself,  and  for  the  best 
commutating  conditions  it  should  vary 
in  proportion  to  the  armature  field,  that 
is,  to  the  armature  current,  except 
where  there  is  saturation  in  the  arma- 
ture flux  path.  To  set  up  this  flux  in 
the  opposite  direction,  the  magnetomo- 
tive-force in  the  commutating-pole 
winding  obviously  must  be  greater  than 
that  of  the  armature  winding  and,  in 
order  that  the  flux  may  vary  in  direct 
proportion    to    the    armature    field,    the 


fig.  2006 — (a) 


commutating  pole  is  excited  by  windings 
connected  directly  in  series  with  the 
armature.  The  commutating  pole  mag- 
netomotive-force can  be  considered  as 
made  up  of  two  components,  one  of 
which  neutralizes  the  armature  mag- 
netomotive-force, and  the  other  sets  up 
the  actual  commutating-pole  flux  that  is 
useful  in  generating  a  voltage  of  the 
proper  value  and  direction  in  the  coils 
undergoing  commutation.  Now  con- 
sider, for  example,  a  commutating  field 
winding  consisting  of  30  turns.  Assume 
that  the  neutralizing  component  is  27 
turns,  and  the  useful  component  is  3 
turns.  If  the  flux  of  the  commutating 
field  winding  were  changed  by  the 
equivalent  of  one  turn  (1/30  or  3.3  per- 
cent) the  useful  component  would  be 
changed  by  33.3  percent.  Either  the 
commutating-pole  field  winding  must  be 
calculated  with  an  extremely  small  per- 
cent of  error,  if  it  is  to  set  up  a  flux  of 
the  proper  value,  or  some  method  of 
regulating  this  flux  must  be  used.  At 
first,  a  plain  resistance  shunt  was  used 
to  regulate  the  current  through  the 
winding,  but  this  had  its  disadvantages 
in  that  the  shunt  and  field  winding  did 
not  properly  proportion  the  current  of 
the  varying  loads,  due  to  the  inductance 
of  the  field  winding  itself,  consequently, 
on  machines  operating  under  frequent 
and  sudden  changes  of  load,  the  result 
of  using  such  a  shunt  tended  to  over- 
balance the  good  results  for  which  the 
commutating  winding  is  used.  The  ad- 
visability of  using  a  different  method 
for  regulating  the  commutating  pole 
flux  became  quite  evident,  and  an  in- 
ductive shunt  has  been  used  to  a  great 
extent  in  place  of  the  plain  resistance 
shunt.  It  is  obvious  that  if  the  proper 
impedance  is  used  in  the  shunt,  the 
winding  and  shunt  will  properly  divide 
the  current  while  operating  under  either 
varying  or  constant  loads.  Hence,  the 
commutating  pole  flux  will  always  have 


its  proper  value  in  the  range  of  opera- 
tion for  which  the  machine  was  de- 
signed, after  the  shunt  has  once  been 
properly  regulated.  Inductive  shunts 
are  still  used  to  some  extent,  but 
another  method  which  is  used  more 
now,  does  not  require  the  use  of  a  shunt. 
In  this  method,  the  commutating  pole 
air-gap  is  changed  by  the  use  of  steel 
liners  placed  between  the  commutating 
pole  and  the  frame.  This  regulates  the 
reluctance  of  the  magnetic  path,  and 
hence  the  flux  that  crosses  the  air-gap  is 
of  the  proper  value  for  good  commuta- 
tion for  all  loads  within  the  range  of 
operation  of  the  machine,  and  no  other 
regulation  is  necessary,  thus  the  use  of 
any  shunt  whatever  is  avoided.  H.  B.  w. 

2007 — Selecting  Turbogenerator  Units 
— Under  the  assumption  that  the  dis- 
tribution losses  of  the  system  are  neg- 
ligible, what  would  be  the  best  unit  to 
select,  a  1500  kv-a,  220  volt  turbogen- 
erator supplying  current  direct  to  a 
220  volt  system  or  a  1500  kv-a,  4600 
volt,  turbogenerator  supplying  current 
to  the  220  volt  system  through  a  bank 
of  step-down  transformers?  Can  you 
give  me  an  approximate  cost  of  the 
two  installations ;  also  approximate 
cost  for  transformers  required  with 
4600  volt  unit.  If  the  220  volt  turbo- 
generator requires  more  floor  space 
and  is  more  expensive  than  the  4600 
volt  unit,  please  give  reasons  why?  In 
both  cases  assume  the  same  power- 
factor  for  a  1500  kv-a,  three-phase,  60 
cycle  system.  j.  E.  M.  (mich.) 

We  would  advise  2400  volts  for  a  1500 
kv-a,  turbo  unit.  On  account  of  the 
large  currents  to  be  handled  by  the 
small  number  of  armature  conductors, 
220  volts  is  too  low.  To  build  a  220  volt 
1500  kv-a  unit  is  almost  impossible. 
Even  if  built  it  would  not  give  satisfac- 
tory service  due  to  the  insulation 
troubles  developed  by  the  excessive 
mechanical  strain  caused  by  the  heavy 
current.  A  4600  volt  unit  is  objection- 
able on  account  of  the  thicker  insulation 
required  in  the  unit  itself  and  the  trans- 
mission lines  and  transformers.  The 
220  volt  unit  would  be  expensive  to  build 
on  account  of  it  not  being  standard 
practice  to  build  this  type  of  machine 
and  the  enormous  increase  in  copper  re- 
quired. The  2400  and  4600  volt  units,  in- 
cluding the  transformers,  would  un- 
doubtedly occupy  more  floor  space  than 
the  220  volt  unit,  but  the  assured  con- 
tinuous service  would  more  than  com- 
pensate for  this  extra  investment. 

F.  D.   N. 

2008  — Carbon-Tetrachloride  Fuse  — 
What  is  the  principle  of  thecarbon- 
tetrachloride  fuse,  and  how  is  it  con- 
structed? P.  N.  p.    (KENTUCKY) 

The  carbon-tetrachloride  fuse  consists 
of  a  long  glass  tube  with  a  metal  ferrule 
at  each  end.  The  tube  contains  a  spiral 
spring,  the  lower  end  of  which  is  fasten- 
ed to  the  bottom  ferrule.  The  spring  is 
stretched  and  the  upper  end  fastened 
to  the  fuse  wire,  which  in  turn  is 
fastened  to  the  upper  ferrule.  The  in- 
side of  the  tube  is  filled  with  carbon-te- 
trachloride or  some  other  liquid  fire  ex- 
tinguisiier,  completely  surrounding  the 
spring  and  short  fuse  wire.  When  an 
overload  conies  on  the  circuit,  the  fuse 
wire  becomes  hot  and  melts.  This  re- 
leases the  stretched  spring  which  con- 
tracts towards  the  bottom  ferrule.  The 
arc  which  is  formed  at  the  fusion  of  the 


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THE    ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  8 


wire  is  drawn  out  longer  and  longer  by 
the  contraction  of  the  spring.  In  addi- 
tion, the  hquid  fire  extinguisher  is  pour- 
ed onto  the  arc  and  aids  greatly  in  its 
extinction.  The  glass  tube  allows  the 
operator  to  observe  the  position  of  the 
spring,  which  indicates  whether  the  fuse 
has  been  blown  or  not.  The  most  gen- 
eral use  of  these  fuses  is  on  the  primary 
side  of  power  and  potential  transform- 
ers.. J.  D.  w. 

20og —  Starting  Sqirkel-Case  Induc- 
tion Motors — If  a  standard  squirrel- 
cage  motor  of,  say,  15  hp,  three-phase, 
60  cycles,  220  volts  is  connected  direct 
to  the  main  switchboard  of  a  20  kv-a 
generating  plant,  driven  by  an  oil  en- 
gine through  a  three-pole  knife  switch 
or  a  three-pole  oil  switch  with  time 
limit  overload  trip  coils  only,  and 
without  any  other  starting  device,  can 
the  motor  be  successfully  started  un- 
der load  by  starting  the  engine  and 
gradually  building  up  normal  voltage 
and  frequency  as  the  engine  runs  up 
to  speed.  About  what  will  be  the 
maximum  starting  torque  developed 
by  a  motor  so  connected  and  about 
what  will  be  the  maximum  current  per 
phase  relative  to  the  normal  full-load 
current?  If  the  motor  starts  with 
light  load  requiring,  say,  approxi- 
mately 50  percent  of  full-load  running 
torque,  about  what  will  be  the  value 
of  current  required  to  start  the  load 
and  run  the  motor  up  to  normal 
speed?  M.  o.  s.  (ill.) 

This  method  of  starting  can  be  used, 
where  possible,  and  will  give  any  value 
of  torque  up  to  almost  pull-out  torque. 
Care  must  be  taken,  however,  to  keep 
the  ratio  of  frequency  to  voltage  as 
nearly  constant  as  possible,  or  near  that 
of  normal  operation,  in  order  that  the 
field  strength  will  vary  as  little  as  possi- 
ble. If  these  conditions  are  maintained 
the  operating  characteristics  as  far  as 
current  and  torque  arc  concerned,  will 
be  about  the  same  as  under  normal  con- 
dition :  so  the  current  required  to  start 
under  a  given  torque  will  be  practically 
the  same  as  that  required  to  develop  the 
same  torque  under  normal  running  con- 
ditions of  voltage  and  frequency.  These 
conditions  hold  if  the  voltage  and  speed 
are  reduced  to  a  very  low  value  at  start, 
something  near  the  full-load  slip.  If 
the  motor  is  started  with  a  higher  value 
of  voltage  and  frequency  than  this,  the 
current  for  a  given  starting  torque  will 
increase  along  the  same  curve  as  for  a 
corresponding  value  of  slip  on  the  speed 
torque  and  speed  current  curves.  For 
the  case  given,  if  the  motor  starts  at  50 
percent  full-load  torque  and  a  starting 
voltage  and  frequency  of  about  one- 
third  normal  value  is  used,  an  ordinary 
motor  will  take  slightly  above  full-load 
current.  c.  w.K. 

2010 — Heating  of  Alternator  Stator 
Core — .\  150  kw,  two-phase,  60  cycle, 
36  pole,  2200  volt  alternator  having  72 
coils  and  144  slots  was  recently  recon- 
nected nine  parallel  for  230  volts. 
When  run  no  load  at  220  volts  the 
field  takes  40  amperes  and  stator 
core  heat  is  noticed  within  five  min- 
utes. When  run  for  two  hours  with 
150  kv-a  load  and  room  temperature 
34  degrees  C,  the  stator  core  registers 
92  degrees  C  and  the  winding  only  65 
degrees  C  and  the  field  takes  62  am- 
peres. The  voltage  began  to  drop 
slowly  near  the  end  of  the  test,  both 


e-xciter  and  main  rheostats  having 
been  cut  all  the  way  out.  The  gener- 
ator is  of  the  revolving  field  type  and 
the  stator  coils  are  each  wound  with 
a  single  wire  looped  through  the  slots 
sixteen  turns.  Can  this  trouble  be  cor- 
rected by  tearing  the  core  down  and 
repainting  the  punchings  and  rewind- 
ing? Judging  from  the  method  of 
winding  the  coils  this  is  the  old  type 
of  machine.  Is  it  possible  the  iron 
may  be  bad  due  to  ageing  and  new 
punchings  be  necessary?  Would  not 
this  have  to  be  a  108  slot  core  for 
three  phase?  G.  E.  D.  (pa.) 

We  have  never  known  of  a  case  where 
ageing  of  the  iron  led  to  an  abnormally 
high  core  rise.  The  high  temperature 
rise  may  be  due  to  any  one  or  a  com- 
bination of  the  following  causes: — (l) 
Loss  of  insulation  .between  individual 
sheets  of  the  armature  core.  (2)  Ob- 
struction by  dirt,  or  otherwise,  of  the 
ventilating  ducts  through  the  armature 
core.  (3)  Failure  to  replace  on  the 
rotor  the  ventilating  fan  blades,  if  there 
are  any,  after  making  repairs.  In  case 
the  trouble  is  due  to  (i)  the  armatures 
should  be  torn  down  and  the  core  plates 
repainted.  For  (2)  and  (3)  the  re- 
medies are  obvious.  A  balanced  three- 
phase  winding  could  not  be  made  with 
the  present  number  of  slots.  If  new 
iron  was  supplied  for  a  three-phase 
winding  there  should  be  108  or  216  slots, 
if  the  present  closed  slot  design  is  re- 
tained. If  open  slots  are  used,  a  bal- 
anced winding  can  be  obtained  with  any 
number  of  slots  which  is  divisible  by 
27,  i.  e.  108-135-162,  etc.  provided  all 
coils  per  phase  are  in  series.  If  the 
groups  are  to  be  parallel  some  of  these 
slot  combinations  would  not  be  permis- 
sible, depending  on  the  number  of  paral- 
lels used.  R-  a.  m. 

2011 — Designing  a  Slip-Ring  Wound- 
Rotor  Winding — When  designing  a 
winding  for  a  slip-ring  wound-rotor 
can  the  same  method  be  employed  as 
was  explained  in  the  Question  Box  of 
July,  iqrS  for  a  stator  winding?  I 
notice  the  chord  factor  for  rotor  wind- 
ings is  unity.     Is  this  always  true? 

G.   w.  s.    (CAL.) 

The  stator  winding  is  the  one  that 
needs  most  of  the  designers  attention 
because  it  must  meet  a  fixed  line  voltage 
and  do  it  without  overworking  or  un- 
derworking its  own  copper  and  magne- 
tic field.  If  we  have  given  a  stator 
iron  core  and  rotor  iron  core  of  a  ma- 
chine of  standard  proportions,  the  num- 
ber of  turns  in  the  secondary  three-phase 
winding  is  practically  of  no  consequence 
to  the  efficiency  and  satisfactory  opera- 
tion of  the  motor,  so  long  as  the  slot 
is  filled  with  a  properly  insulated  wind- 
ing and  the  throw  is  not  less  than  two- 
thirds  pitch.  However,  it  sometimes 
happens  that  certain  given  units  are 
available  for  use  as  secondary  control ; 
such  parts  as  switches  which  will  limit 
the  current  which  motor  should  have 
at  full  load ;  or  grids  which  are  better 
adapted  for  a  given  voltage  and  current. 
Let.  Ei  =  Locked  voltage  per  leg  of 
rotor  winding;  B,=  Voltage  per  leg  of 
stator  winding  (terminal  to  neutral,  if 
star);  d.  /.  =  Distribution  factor ;=  0.90 
for  two  phase  0.955  for  three  phase; 
ch.    f.  =  Chording     factor 

[slots  spanned 
! 


—  current   per   ring   divided   by    1.73   if 
delta.  Then,  given  /  to  start  with, 
y.f6  X  /Vp 

Where    A'j  =   re- 


£2^  ~ 


;iiX9o' 


slots  per  pole 
load  amperes  per  leg  of  rotor  winding 


l'= 


Full 


i  X  /  X  0.9S  • 
resistance    to    permit     full-load    torque 
starting  on  first  notch, 

'■•-  f 

Solving   for  transformation  ratio  be- 
tween rotor  and  stator  winding, — 

£1 
The  required  number  of  series  conduc- 
tors per  phase  in  the  rotor  must  equal,— 
d  X  A"  X  d.  f.  X  ch.f.  01  stator 
d.  /.  X  di.f.  oj  lotor 
where  A':^the  number  of  scries  conduc- 
tors per  phase.  The  numberd  of  series 
conductors  per  slot  is  equal  to  the 
series  conductors  per  phase  multi- 
plied by  the  number  of  phases  and  di- 
vided by  the  number  of  slots  in  the  ro- 
tor. Rotor  windings  are  generally  either 
wave  or  lap  windings.  The  wave  type 
is  generally  full  pitch  because  no  saving 
in  copper  is  made  by  chording.  If  it 
is  not  full  pitch,  it  is  chorded  so  as  to 
get  the  short  throw  on  the  connection 
end  to  prevent  the  connections  from  ex- 
tending too  far  away  from  the  core.  .A 
rolor  lap  winding  should  be  chorded  as 
a  rule  to  three-fourths  or  five-sixths  of 
full  pitch,  because  the  amount  of  cop- 
per and  room  saved  more  than  offsets 
the  loss  in  locked  voltage.  h.   s.  s. 

2012 — FiFXD  Switch  and  Discharge  Re- 
sistance— Please  advise  the  best 
practice  in  the  use  of  field  switches 
for  direct-current  generators,  i.  e.  two 
and  three  wire,  125,  250  and  600  volts, 
turbine,  engine  or  motor  driven  gen- 
erators, of  commercial  sizes.  Kindly 
give  me  also  the  reasons  for  the  parti- 
cular practices  in  this  matter,  the 
generators  also  to  operate  single  or  in 
parallel  with  others.  The  information 
I  desire  is,  when  to  use  a  field  switch 
and  discharge  resistance  and  when  not 
to.  o.  w.  c.   (d.  c.) 

We  do  not  believe  that  field  switches 
for  direct-current  machines  are  neces- 
sary or  even  desirable  in  the  great  ma- 
jority of  cases.  As  a  matter  of  fact, 
the  use  of  field  switches  with  machines 
operating  in  parallel  introduces  a  con- 
siderable hazard,  because  the  accidental 
opening  of  the  field  switch  on  one  gen- 
erator would  cause  practically  a  dead 
short-circuit  on  the  other  machines. 
This  heavy  short  circuit  current  would, 
of  course,  flow  into  the  machine  having 
its  field  circuit  open  until  interrupted  by 
automatic  protective  devices.  In  a  few 
special  cases,  field  switches  may  be  ap- 
plied to  advantage,  generally  when  a 
single  generator  feeds  some  smgle  load 
directly,  as  for  instance,  a  direct-con- 
nected exciter  supplying  its  own  gen- 
erator field.  In  this  case,  excitation  can 
be  put  on  or  taken  off  the  main  alterna- 
tor through  an  exciter  field  switch 
mounted  on  the  switchboard.  In  this 
way,  the  necessity  for  carrying  the  heavy 
exciter  main  leads  to  the  switchboard  is 
eliminated,  or  the  more  or  less  expen- 
sive remote  control  solenoid  operated 
circuit  breakers  are  rendered  unneces- 
sary. Discharge  resistors  should  be  used 
with  every  installation  of  field  switches. 

R.  C.  S. 

2013— Testing  Large  Turbogenerator 
— How  are  the  coils  tested  during  the 
various    stages    of    building   of    large 


August,  1 92 1 

turbos?  What  is  the  most  suitable  ca- 
pacity of  testing  transformer  used  for 
testing  windings  of  large  turbos  ? 

N.    B.    (RHODE   island) 

These  coils  are  wound  on  formers, 
then  insulated  in  line  with  the  specifi- 
cations. A  test  is  then  made  for  short- 
circuits  between  turns  before  treatment, 
and  an  insulation  test  is  made  on  the 
coils  before  they  are  wound  into  the 
machine.  Before  cross  connections  are 
made,  another  check  is  made  for  short- 
circuit  between  turns  and  after  connect- 
ing an  insulation  test  is  made  on  the  en- 
tire winding.  A  30  kw  testing  trans- 
former is  most  suitable  for  this  work. 

L.  E.   s. 

2014— Violet  Ray—  Kindly  give  a  de- 
scription of  the  apparatus  necessary 
for  the  production  of  the  violet  ray? 
H.  p.  w.  (IND. ) 
Ultraviolet  radiation  is  produced  in 
abundance  by  an  arc  between  nearly  any 
kind^  of  metallic  electrodes.  Mercury 
and  iron  are  most  used.  Since  the  more 
useful  radiation  (of  shorter  wave 
lengths)  will  not  pass  through  glass, 
windows  and  lenses  of  glass  cannot  be 
used.  Quartz  windows  and  lenses  may 
be  used  freely  since  quartz  transmits  the 
ultra  violet  ray.  By  far  the  most  con- 
venient source  of  ultraviolet  radiation 
is  the  commercial  quartz  mercury  arc 
with  automatic  control,  such  as  was  in 
common  use  from,  1905  to  1910.  This 
is  mounted  on  an  opening  in  the  top  of 
a  box  provided  with  a  sliding  glass  side 
for  observation.  Eczema  i»  treated  by 
simply  inserting  the  affected  member 
under  the  arc,  6  to  15  inches  from  the 
bulb.  When  higher  intensities  are  de- 
sired, an  image  of  the  arc  is  thrown  on 
the  affected  part  by  means  of  a  large 
quartz  lens  of  about  2.5  inches  diameter 
and  6  inches  focal  length.  Highly  con- 
centrated radiation  for  the  treatment  of 
lupus  is  obtained  by  focusing  an  image 
of  an  iron  arc  directly  on  the  part  to 
be  treated.  Rods  of  ordinary  iron,  % 
to  i  inch  in  diameter  are  used  as  elec- 
trodes. The  arc  is  enclosed  to  protect 
the  operator.  A  side  tube  about  three 
inches  in  diameter  and  two  feet  long 
carries  the  quartz  focusing  lens  in  its 
center  and  has  the  iron  arc  at  one  end 
and  the  part  to  be  treated  at  the  other. 

p.   C.    N. 

2015— Secondary  Current  of  Induction 
Motor— When  is  the  secondary  cur- 
rent of  a  variable-speed,  phase-wound 
induction  motor  largest  when  (a) 
driving  a  fan;  (b)  driving  a  centri- 
fugal pump;  (c)  driving  a  load  re- 
quiring constant  torque  such  as  an  air 
compressor.  Assume  motors  which 
have  (4)  percent  slip  on  full  load 
with  secondary  rings  short-circuited. 
Of  course,  the  above  question  is  for 
running  conditions.  h.   h.    (ohio) 

The  secondary  current  does  not  de- 
pend on  the  kind  of  load  but  on  the 
amount  of  load  the  motor  is  carrying. 
The  secondary  current  varies  almost  in 
direct  proportion  to  the  load  in  any 
particular  motor,  but  the  values  of  cur- 
rents in  different  motors  do  not  follow 
any  rule,  as  they  are  varied  to  suit  man- 
ufacturing conditions.  If  you  mean  to 
inquire  at  what  running  speed  the 
secondary  current  will  be  greatest,  this 
will  depend  altogether  on  the  relation 
between  the  horse-power  and  the  speed 
of  the  driven  load.  The  power  input  to  a 


THE   ELECTRIC  JOURNAL 


centrifugal  pump  or  fan  varies  approxi- 
mately with  the  cube  of  the  speed.  In- 
creasing the  resistance  in  the  secondary 
decreases  the  speed  of  the  induction  mo- 
tor and  when  driving  a  fan  or  centrifu- 
gal pump  the  load  will  drop  off  rapidly 
with  the  decrease  in  speed.  As  the  de- 
crease in  load  will  lend  to  decrease  the 
percent  slip  with  a  given  resistance,  it  is 
apparent  that  two  conflicting  tendencies 
are  introduced  which  will  to  a  certain 
extent  nullify  one  another.  That  is, 
the  decrease  in  the  speed  that  will  be 
obtained  with  a  given  resistance  is  much 
less  when  driving  a  fan  than  when  driv- 
ing a  constant  torque  load.  In  either  case 
however,  the  horse-power  will  be  less 
at  the  lower  speed.  The  current  in  the 
secondary  will  vary  directly  with  the 
torque  up  to  about  50  percent  overload  ; 
if  the  torque  decreases  with  the  speed, 
the  secondary  current  will  also  decrease 
with  the  speed.  But  if  the  torque  is 
constant  regardless  of  speed  then  the 
secondary  current  will  be  constant  at 
all  speeds  within  the  range  which  can 
be  produced  by  inserting  resistance. 
The  above  statements  are  independent 
of  the  amount  of  resistance  inserted  in 
the  secondary.  c.  R.  R. 

2016 — Drying  Out  a  Vertical  Motor — 
We  have  a  550  hp,  2200  volt,  three- 
phase  vertical  motor,  with  wound  ro- 
tor for  driving  a  large  water  pump. 
The  motor  is  seldom  used,  therefore 
moisture  collected  in  the  windings  and 
it  was  necessary  to  dry  the  machine. 
We  dried  this  motor  with  220  volts  or 
60  amperes  in  the  stator  windings  by 
short-circuiting  the  rotor  winding  on 
the  collector  rings.  After  drying  the 
windings  in  the  above  manner  for  two 
weeks  we  tested  the  insulation  and  it 
showed  a  resistance  of  four  megohms 
to  ground.  In  running  the  motor 
again  we  found  that  the  air-gap  is 
not  even  all  around  and  the  collector 
rings  are  not  running  true.  The  mo- 
tor draws  more  current  than  usual,  in 
fact  it  is  over-loaded.  Is  it  possible 
that  the  shaft  is  sprung  due  to  uneven 
pull  on  the  core?  Or  is  the  shaft 
warped  due  to  uneven  heating  on  part 
of  the  winding?  If  so  please  explain 
how  we  can  remedy  it? 

M.  T.  C.    (hAWAIAN  islands) 

This  shaft  could  not  be  sprung  by 
uneven  pull  in  the  air-gap,  nor  by  uneven 
heating.  The  shaft  could  only  be 
sprung  by  some  outside  mechanical 
force.  This  should  be  checked  with 
gauges  on  the  shaft  and  gauges  in  the 
air-gap  when  the  rotor  is  in  different 
positions.  The  uneven  air-gap  could  be 
caused  by  worn  bearings  and  this  should 
be  checked.  The  collector  ring  insulation 
may  have  warped  and  thrown  the  rings 
out  of  true.  If  the  shaft  is  not  sprung, 
the  rings  should  be  trued  up.  c.  w.  K. 

2017— Efficiency  of  Rebuilt  Motors — 
What  efficiency  is  to  be  expected  from 
rebuilt  motors,  having  been  through  a 
fire?  The  copper  was  not  melted  in 
any  stator  or  rotor  coils.  They 
range  in  size  from  15  to  100  hp. 
End  bells,  shafts,  rotors  and  stators 
after  being  carefully  checked,  show 
little  or  no  warping.  By  using  factory 
data  on  all  replacements,  is  it  possible 
to  obtain  nearly  as  good  results  as 
original?  What  bad  effect  has  heat 
on   stator  laminations? 

R.  P.  M.   (utah) 


377 

There  are  two  things  in  the  primary 
core  which  are  affected  by  heat,  the  iron 
itself  and  the  japan  on  the  punchings. 
The  iron  itself  will  be  annealed  or  even 
burnt,  depending  on  how  hot  the  motor 
was  and  how  long  it  lasted.  The  right 
amount  of  heat  applied  long  enough  will 
be  beneficial  in  decreasing  the  iron  loss, 
but  too  much  heat  will  oxidize  the  iron 
thus  leaving  less  real  iron  to  carry  the 
flux,  causing  the  core  loss  to  be  greater. 
The  japan  on  the  punchings  will  be 
burnt  and  may  or  may  not  allow  the 
punchings  to  touch  and  increase  the 
eddy  current  losses  in  the  iron.  About 
the  only  way  to  tell  whether  these  mo- 
tors should  be  rewound  is  to  take  the 
one  which  looks  the  worst  and  rewind 
it,  taking  the  losses  at  no  load  and  com- 
paring them  with  the  tests  of  the  motor 
when  new.  If  this  shows  very  little 
increase  it  would  be  all  right  to  rewind 
all  the  motors.  c.  w.  k. 

2018 — Transmission  Line — It  is  pro- 
posed to  run  a  power  line  34  kilo- 
meters to  supply  500  kilowatts  at  80 
percent  power-factor  (lagging).  We 
generate  at  600  volts,  three-phrase  60 
cycles  ungrounded  neutral  and  pro- 
posed to  step  up  to  22000  volts  and 
step  down  again  to  600  volts  at  the 
other  end  for  distributing  to  squir- 
rel-cage motors  driving  centrifugal 
pumps.  The  transmission  line  is  to 
be  No.  2  B.  &.  S.  copper  wire  strung  in 
the  form  of  an  equilateral  triangle 
with  three  foot  sides  on  galvanized 
iron  posts  35  ft.  high,  and  set  80 
meters  apart  and  a  ground  line  of 
No.  12  copper.  How  often  would  it 
be  necessary  to  have  anchor  posts  ? 
What  would  be  the  power  loss  at 
full  load?  What  should  be  the  over- 
all efficiency  of  the  system  (Ratio 
of  power  put  in  transformer  at  send- 
ing end,  to  power  available  at  low- 
tension  side  of  transformer  at  receiv- 
ing end).  There  is  a  group  of  three 
telegraph  lines  running  parallel  with 
the  proposed  power  route  for  about 
24  kilometers.  How  far  would  we 
have  to  keep  away  from  these  to 
avoid  inductive  interferences?  Would 
50  ft.  be  sufficient  clearance  and  would 
it  be  necessary  to  transpose  the  power 
lines?  E.  M.  o.   (Mexico) 

For  normal  conditions  it  will  be 
necessary  to  have  one  anchor  post  per 
mile ;  however,  you  may  need  more  than 
this,  dcpendingupon  the  factors  which  in- 
fluence their  use.  Our  experience  shows 
that  No.  12  copper  wire  may  give  trou- 
ble, if  used  as  a  ground  line  on  this 
system.  It  would  be  better  to  use  a 
No.  6  copper  clad  ground  wire.  The 
voltage  at  the  receiver  end  will  be  igooo 
volts  at  full  load.  This  is  based  on 
the  assumption  that  the  receiver  trans- 
former will  be  rated  at  670  to  700 
kv-a,  22000-600  volts.  This  arrange 
ment  will  give  a  receiver  voltage  of 
650  volts  at  no  load,  and  550  volts  at 
full-load.  The  powerloss  at  full-load  will 
be  34  kw,  and  the  overall  efficiency 
will  be  93.5  percent.  It  will  not  be  neces- 
sary for  you  to  transpose  the  power 
lines.  The  clearance  of  fifty  feet  will 
be  sufficient  for  normal  conditions  on 
the  power  system.  If  the  system  is 
not  grounded,  you  need  not  anticipate 
trouble  from  inductive  interference  in  the 
telegraph  lines  in  case  of  a  ground. 
For  a  grounded  neutral  system,  induc- 
tive interference  may  occur  in  case  of 
a   ground   on   the   transmission   system. 


378 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


This  interference  is  only  of  a  momen- 
tary nature,  as  it  ceases  when  the  cir- 
cuit breaker  opens.  An  article  by  Mr. 
A.  W.  Copley  in  the  Jourx.\l  for  Aug. 
1920  gives  important  facts  on  the  sub- 
ject of  inductive  interference,     c.  M.   H. 

2019 — Motor  Specifications — The  fol- 
lowing is  a  copy  of  motor  specifica- 
tions we  have  written  on  some  direct- 
current  machines :  35  hp  motors, 
direct-current,  230  volts,  adjustable 
speed,  shunt  wound,  interpole,  400  to 
1600  r.  p.  m.,  constant  service.  Tem- 
perature limits  40  degrees  C.  and  45 
degrees  C.  commutator,  at  full  load. 
Have  we  a  right,  under  these  specifi- 
cations, to  e.xpect  full  load  of  35  hp 
at  40  degrees  C.  temperature  rise  at 
any  speed  between  400  r.  p.  m.  and 
1600  r.  p.  m.  inclusive?      ,T.  11.  d.  Cp.\.) 

This  specification  would  be  interpreted 
to  mean  that  the  temperature  rise  should 
not  exceed  40  degrees  C.  for  a  35  hp 
load  at  any  speed  from  400  to  1600  r. 
p.  m.  The  specification  should  read 
"Temperature  rise  not  to  exceed  JO  de- 
grees C."  instead  of  "Temperature  limits 
40  degrees  C."  r.    w.   o. 

2020 — Soldered  Joint — Can  you  give 
me  any  general  data  regarding  the  al- 
lowable current  density  across  a 
soldered  joint,  as  for  example,  con- 
necting leads  soldered  to  field  coils  of 
a  turbogenerator.  In  other  words,  in  a 
case  where  all  the  current  must  pass 
directly  across  the  soldered  joint 
from  copper  to  copper. 

N.  c.   H.   (ariz.") 

It  is  the  usual  practice,  when  the  mem- 
bers to  be  soldered  have  a  large  cross- 
section,  to  consider  the  current  carry- 
ing capacity  of  the  soldered  union  to 
be  equal  to  that  of  the  adjacent  solid 
material.  This  practice  is  justified  by 
the  fact  that  the  intervening  film  of 
solder  is  very  thin.  Where  strap  sec- 
tions, having  a  thickness  of  i":!  inch  or 
less,  are  soldered,  the  film  thickness  is 
an  appreciable  factor  in  lowering  the 
current  carrying  capacity,  so  that  it  is 
customary  to  rate  the  joint  at  one-half 
the  current  carrying  capacity  of  the 
solid  copper.  o.  h.  e. 

2021 — Startinc,  Synchronous  Motors — 
Kindly  advise  me  of  the  various 
methods  of  starting  synchronous  mo- 
tors. In  starting  a  220  volt,  synchron- 
ous motor  with  field  circuit  open  and 
using  a  no  volt  tap  on  the  starting 
autotransformer,  does  the  motor  reach 
full  synchronous  speed  or  is  there  a 
slip?  Why  is  it  advisable  to  start  a 
synchronous  motor  by  applying  a  re- 
duced voltage  to  the  stator  and  then 
applying  a  weak  field  before  applying 
full  voltage  to  the  stator?  Does  it 
make  any  difference  whether  the  field 
is  applied  before  the  machine  has 
reached  full  speed  or  after? 

M.    M.    R.     (OHIO') 

Any  synchronous  motor  will  start 
itself  as  an  induction  motor  when  alter- 
nating current  is  introduced  into  its 
armature  winding.  Some  motors  will 
start  more  eflSciently  in  this  way  than 
others,  depending  upon  the  construction 
of  the  rotating  part.  With  laminated 
field  poles  there  is  very  little  chancf  for 
the  armature  current  to  induce  cur- 
rents in  the  revolving  part  and  rela- 
tively little  torque  will  be  developed. 
A   rotor  with   solid  field   poles   permits 


better  circulation  of  the  induced  cur- 
rents and  hence,  will  develop  consider- 
ably more  torque.  A  rotor  provided 
with  a  cage  winding  similar  to  the  cage 
winding  of  an  induction  motor  will  de- 
velop a  still  greater  torque.  All  syn- 
chronous motors  should  be  started  with 
the  field  short-circuited  through  the 
field  rheostat  set  in  the  running  posi- 
tion. In  case  the  machine  is  started 
with  the  field  open,  there  is  a  high  volt- 
age induced  in  the  field  coils.  In  a 
great  many  cases  this  voltage  is  high 
enough  to  be  dangerous  to  the  operator, 
since  it  appears  at  the  field  switch,  and 
may  cause  a  break  down  in  the  field 
insulation,  unless  special  precautions  are 
taken  at  the  instant  of  starting  and  at 
low  speed.  There  is  usually  a  slight 
gain  in  the  starting  torque  for  a  given 
value  of  line  current  when  the  field  is 
open  circuited.  The  maximum  speed 
which  the  machine  will  reach  as  an  in- 
duction motor  is  higher  when  the  field 
is  closed  during  starting,  consequently 
its  ability  to  pull  into  step  is  greater 
when  the  field  is  excited.  This  gain  is 
usually  of  more  importance  than  the 
small  increase  in  initial  starting  torque 
obtained  by  leaving  the  field  open. 
When  the  motor  reaches  full  speed  on 
the  half  voltage  the  fields  should  be 
e.xcited  before  switching  the  machine 
to  full  voltage.  The  full  speed  on  half 
voltage  may  be  synchronous  speed ;  how- 
ever, generally  it  is  slightly  less,  due 
to  the  slip  which  may  occur  before  the 
rotor  is  locked  in  step  by  the  exciting 
current.  The  field  should  be  excited 
when  the  motor  has  reached  full  speed 
at  half  voltage,  which  can  be  a  little 
less  than  synchronous  speed,  and  be- 
fore switching  the  motor  to  full  volt- 
age. The  field  current  will  not  only  lock 
the  rotor  in  step  but  if  it  is  not  running 
at  synchronous  speed  it  will  tend  to 
pull  it  into  step  and  hold  i*  .there.  Pro- 
vision must  be  made  for  starting  at  a 
reduced  voltage  in  order  to  keep  the 
armature  current  within  a  reasonable 
value.  M.  M.  B. 

2022— Flash  Over  of  Sup  Rino  Motor 
— What  would  cause  a  slip  ring  in- 
duction motor  to  flash  over  across 
the  collector  rings  and  brushholders.  I 
suppose  an  open  circuit  in  secondary 
would  cause  that,  but  in  this  case 
there  is  no  open  circuit,  the  attendant 
in  charge  of  the  motor  claims  that 
motor  flashed  over  before,  and  when 
he  tried  to  start  it  again  it  started 
right  off.  I  was  sent  on  the  job  and 
the  only  thing  I  found  was  that  one 
phase  of  the  secondary  was  left  open 
when  the  equipment  was  installed.  I 
closed  it  by  connecting  D,  E,  and  F 
to  a  common  point  to  form  a  star 
connection  on  the  outside  of  resis- 
tor grid  and  had  no  better  result. 
The  motor  flashed  over  just  the  same. 
The  motor  was  left  idle  for  several 
days  and  was  tried  again  and  this 
time  started  without  flashing  over. 
The  machine  in  question  is  a  206  hp, 
three-phase,  60  cycle.  2200  volts,  52 
amperes  per  terminal,  575  r.  p.  m.. 
induction  motor.  F.  .\.  B.   Cpa.) 

The  only  explanation  we  can  see  is 
that  some  times  the  rotor  stops  with 
some  dirt  or  other  foreign  substance 
under  a  brush.  Then  when  it  is 
started  the  highest  voltage  is  applied 
across  this  poor  contact,  which  burns 
up  and  causes  a  flash  which  may  reach 


to  the  next  ring  and  cause  a  short- 
circuit.  On  starting  again  it  will  start 
O.  K.  if  the  first  flash  burnt  the  ob- 
stacle away  sufficiently  to  give  a  fairly 
good  contact.  See  that  the  collector 
rings  and  the  insulation  between  rings 
are  kept  clean.  c.  w.  k. 

2023 — Motor-Generator  Set —  We  have 
a  motor-generator  set  which  seems  to 
be  over  compounded.  The  name-plate 
data  of  the  generator  is: — 37.5  kw,  250 
volts,  150  amps.  850  r.  p.  m.  The 
name-plate  data  of  the  induction  mo- 
tor is  as  follows  ; — 50  hp,  two-phase, 
200  volts,  120  amps  per  terminal,  full 
load  speed  850  r.  p.  m.  This  machine 
is  running  at  8go  to  895  r.  p.  m.  in- 
stead of  850  r.  p.  m.  receiving  power 
from  a  220  to  230  volt  circuit  sup- 
plied from  4400/230  volts  transformer. 
I  have  put  all  kinds  of  shunt  resist- 
ances in  between  the  series  fields  try- 
ing to  balance  the  voltage.  The  di- 
rect-current volt.ige  pumps  from  220 
to  245  volts  on  a  50  ampere  load.  No 
matter  how  much  resistance  we  in- 
sert in  the  series  field,  the  voltage 
will  not  balance.  We  checked  up  the 
wiring  and  it  seems  to  be  right.  Con- 
necting the  generator  long  or  short 
shunt  will  not  make  any  difference. 
When  a  heavy  load  is  applied  the 
voltage  increases  to  such  an  extent 
as  to  burn  out  230  volt  lamps.  Is  this 
trouble  due  to  the  machine  running 
above  rated  speed?  Would  annealing 
the  pole  pieces  do  any  good? 

M.  J.  vv.  (pa.) 

From  your  data  giving  the  terminal 
voltages  at  different  loads  it  appears 
that  your  trouble  is  due  to  the  machine 
being  over  compounded.  Your  data 
does  not  give  the  voltage  regulation  for 
different  values  of  shunt  resistance,  but 
as  the  resistance  of  the  shunt,  which 
is  connected  in  parallel  with  the  series 
field,  is  decreased  and  more  and  more 
current  shunted  out  of  the  series  field, 
the  increase  in  voltage  as  the  machine 
is  loaded  becomes  less  and  less  until 
the  point  is  reached  where  practically 
all  of  the  current  is  shunted  out  of  the 
series  fields,  when  the  terminal  volt- 
age of  the  machine  will  fall  off  as  the 
load  is  thrown  on.  Check  your  series  field 
shunt  connection  to  see  if  it  is  in 
parallel  with  the  series  field — short-cir- 
cuit the  series  shunt  and  load  the  ma- 
chine— the  terminal  voltage  should  fall 
off.  Your  trouble  is  not  due  to  the 
machine  running  above  rated  speed  nor 
would  annealing  the  pole  pieces  have 
any  effect.  Examine  the  original  shunt 
furnished  w'ith  the  machine  and  see  that 
it  is  making  good  contact — if  it  is,  try 
shifting  the  brushes.  Shifting  the 
brushes  in  the  direction  of  rotation  on 
a  generator  reduces  the  compounding ; 
shifting  them  in  a  direction  against  ro- 
tation increases  the  compounding.  Care 
must  be  taken,  however,  that  the  brushes 
are  not  shifted  so  far  that  commuta- 
tation  is  impaired.  If  the  old  shunt  has 
been  broken  or  destroyed  a  new  one 
can  be  made.  Data  can  be  obtained 
to  have  the  machine  shunted  to  give 
any  degree  of  compounding  by  substi- 
tuting a  rheostat  in  series  with  an  am- 
meter for  the  series  shunt.  By  vary- 
ing the  rheostat  until  the  correct  de- 
gree of  compounding  is  obtained  and 
reading  the  shunted  current  a  shunt  can 
be  made  to  duplicate  that  compounding. 


August,  1 92 1 


THE   ELECTRIC   JOURNAL 


379 


2024 — Cementing  Flexible  Insulation 
—What  can  be  used  to  cement  the 
gauze  back  on  the  insulation  used  in 
motor  slots  which  will  leave  the  in- 
sulation flexible?  I  have  used  shel- 
lac but  this  is  too  brittle. 

G.   W.   S.    (calif.) 

The  shellac  may  be  made  flexible  by 
adding  a  little  castor  oil  and  stirring 
until  it  is  dissolved.  The  amount  of  oil 
to  use  can  be  determined  by  trial,  but 
probably  will  be  about  10  or  15  per- 
cent. L.   E.   F. 

2025 — Com  .MUTATOR  Troubles — I  have 
a  75  hp,  direct-current,  220  volt  shunt 
wound  conimutating-pole  motor  driv- 
ing a  50  kw  alternator  which  has  been 
in  operation  since  last  October.  The 
commutator,  instead  of  coloring  up  to 
a  chocolate  color  all  around,  will  be 
streaked  with  a  bright  place  about 
one-half  an  inch  wide  and  then  again 
it  will  vary  to  different  widths  that 
will  go  around  the  commutator  only 
about  half  way.  The  commutator  is 
smooth  and  the  brushholders  are  all 
in  line,  about  Yf,  in.  away  from  the 
commutator.  There  is  no  sparkling 
at  any  of  the  brushes.  I  put  in  four 
new  brushes  where  the  trouble  was, 
thinking  there  was  a  hard  place  in 
the  old  brushes  but  it  did  no  good. 
Little  specks  of  copper  collected  on 
the  frame  of  the  machine.  I  cleaned 
the  slots  of  the  commutator  and  what 
seemed  to  be  mica  dust  came  out  of 
them.  After  that  the  commutator 
took  on  a  good  color  but  did  not  stay 
that  way  long.  Kindly  inform  me  if 
there  is  anything  that  I  could  do  to 
make  the  commutator  take  a  uniform 
color  all  around.       h.  a.  b.    (mass.) 

At  the  positive  brushes  on  a  motor, 
the  current  passing  from  the  brush  to 
the  commutator  carries  along  minute 
particles  of  carbon.  These  particles 
tend  to  give  to  the  commutator  a  dark 
glossy  finish.  At  the  negative  brushes, 
the  current  passing  from  the  commu- 
tator to  the  brushes  tends  to  carry  along 
minute  particles  of  copper.  The  re- 
moval of  these  particles  tends  to  give 
to  the  commutator  a  bright,  raw  appear- 
ance. For  some  unknown  reason,  at 
places  on  the  commutator  the  effect  of 
the  latter  action  is  greater  than  that  of 
the  former.  The  fact  that  a  change  of 
brushes  did  not  help  indicates  that  the 
trouble  is  not  caused  by  a  defect  of 
the  brushes.  If  the  trouble  were  caused 
by  a  defect  of  the  brushes  or  brush- 
holder  rigging,  the  bright  places  should 
extend  entirely  around  the  commuta- 
tor. As  this  condition  does  not  exist, 
the  cause  of  the  bright  places  is  proba- 
bly something  about  the  armature. 
From  the  data  given  it  is  impossible 
to  tell  definitely  what  is  wrong.  The 
most  probable  cause  of  the  bright  place 
is  that  the  slots  between  the  commutator 
bars  are  not  thoroughly  cleaned  out 
oyer  the  whole  width  of  the  mica.  Pos- 
sibly small  pieces  of  mica  extend  up 
at  each  side  of  the  slot  and  the  brush 
rides  on  these  pieces  of  mica,  causing 
a  slight  sparking  underneath  the  brush. 
This  sparking  would  then  eat  away  the 
commutator  causing  a  bright  place 
about  where  the  mica  projects.  Fre- 
quently, to  avoid  any  possibility  of  all 
mica  not  being  cleaned  out,  the  slot 
made  in  undercutting  is  made  even  wider 
than  the  thickness  of  the  mica.         s.  H. 


2026 — THERMorHONE — Can  you  give  me 
any  information  regarding  the  ther- 
mophone?  Can  this  instrument  be 
used  in  connection  with  an  earphone? 
w.  w.  K.  (mass.) 
The  thermophone  is  an  instrument 
for  measuring  temperature,  particularly 
the  temperature  of  a  distant  or  inac- 
cessible place.  It  is  used  for  the  pur- 
pose of  determining  temperature  of  the 
water  of  lakes  and  ponds  at  various 
depths.  Thermophones  are  embedded 
in  the  masonry,  during  the  construction 
of  dams  in  order  to  determine  the  ther- 
mal changes  in  the  large  masses  of 
masonry.  The  thermophone  consists  es- 
sentially of  two  coils  of  many  turns 
of  fine  wire  of  two  metals  having  dif- 
ferent temperatures  coefficients  of  elec- 
trical resistance,  connected  in  circuit 
with  batteries  and  a  galvanometer.  The 
wires  of  the  coils  are  of  such  size 
and  length  that  a  small  change  in  tem- 
perature causes  a  measurable  change  in 
electrical  resistance,  which  is  indicated 
by  a  galvanometer  or  detected  by  a  tele- 
phone by  moving  the  pointer  of  a 
Wheatstone  bridge  until  the  silent  point 
is  reached.  The  sensitive  coils  are  con- 
structed of  copper  and  nickel  silver 
wire,  and  are  enclosed  in  a  brass  tube 
Yz  in.  in  diameter  and  8  in.  long.  The 
resistance  of  the  sensitive  coils  must 
be  kept  low  enough  to  get  sufficient 
sensitiveness  when  using  an  ordinary 
telephone  and  it  must  be  kept  high 
enough  to  avoid  the  error  caused  by 
the  heating  of  the  wires  by  the  battery 
currents.  Dealers  selling  supplies  for 
civil  engineers  should  be  able  to  pro- 
cure thermophones  for  you.  M.  M.  B. 

2027 — Effective  Core  Area — On  page 
189  of  EHidley's  "Connecting  Induc- 
tion Motors",  he  shows  how  to  find 
the  flux  capacity  of  the  core  of  an  in- 
duction motor.  The  motor  I  have 
in  mind  has  several  rivets  through  the 
core  of  the  punchings.  Does  this  con- 
struction reduce  the  effective  core  area 
or  do  the  rivets  carry  flux  the  same 
as  the  punchings? 

E.  l.  c.  (ohio) 
In  this  type  of  motor  the  average 
value  of  the  largest  and  smallest  di- 
ameters may  be,  used  as  the  outside  di- 
ameter. A  rivet  is  not  figured  as  car- 
rying flux  but  the  iron  below  the  rivet 
is  figured  as  being  effective.        c.  w.  k. 

2028 — Capacity  Susceptance — I     would 
be  pleased  to  know  the  meaning  and 
value  of  the  term  and  how  it  is  evalu- 
ated. H.  c.  o.   (new  Zealand) 
In    a   simple   condenser,   the   charging 
current    leads    the   voltage   drop    by   90 
degrees.      The   charging   current   is   nu- 
merically  equal   to   the   product   of   the 
voltage   drop   times  the   factor    2  -r  f  C 
which  is  called  the  capacity  susceptance ; 
or  /c  =  Ec  2  V  f  C,  where  /  :=  frequeocy, 
C^Capacity  of  condenser  in  farads 

and   capacity   susceptance:  =  ^  it/ c  =-^ 

Capacity  susceptance  is  expressed  in 
ohms  or  microhms.  A  capacity  of  one 
microfarod  at  60  cycles  has  a  capacity 
susceptance    of    377    microhms    or    377 

X  — «  ohms.  M.  M.  B. 


This  is  more  a  manufacturing  reason 
and  a  conservation  of  winding  space 
than  anything  else,  although  winding 
a  coil  in  two  sections  with  an  insulating 
washer  between  reduces  the  voltage  be- 
tween turns  to  half  the  voltage  of  a 
coil  wound  in  one  section.  If  the  coil 
were  wound  in  one  section,  however, 
it  would  be  necessary  to  bring  one  lead 
out  along  the  side  of  the  winding,  where- 
as in  winding  in  two  sections  the  start 
of  one-half  is  connected  through  the 
insulating  washer  to  the  start  of  the 
second  half  and  the  two  are  wound  in 
opposite  directions  to  form  a  continuous 
winding.  This  brings  both  leads"  out 
on  top  and  facilitates  the  attaching  of 
terminals  or  other  external  connections 
to  the  best  advantage.  This  is  true  in 
practically  all  alternating-current  mag- 
net coils  where  the  copper  section  is 
comparatively  large  and  the  coils  wound 
on  nonautomatic  machines  and  does 
not  apply  to  brake  magnets  alone. 

H.    C.    J. 

2030 — Numbers  on  Armature  Shaft — 
I    have    found    a    series    of    numbers 
stamped  on  one  end  of  the  shaft  of 
motors    and    generators,    and    I    have 
been  told  that  these  indicate,  to  anyone 
who  can  read  them,  all  the  details  of 
the    winding,    such    as    size   of    wire, 
number   of   turns,   pitch,   etc.     Is   this 
■true?     If  so,  please  tell  me  where  I 
can  get  a  copy  of  the  code  which  ex- 
plains them.  G.  D.  (sask.) 
The      statement     that     the     number 
stamped  on  the  end  of  the  rotor  shaft 
indicates  all  the  details  of  the  winding 
is  in  one  sense  true,  but  in  another  sense 
it  is  untrue.     Before  a  motor  of  the  in- 
dustrial  size   is   shipped,   a   serial   num- 
ber is    assigned    to    the    rotor    and     is 
stamped  on  the  end  of  the  shaft.     This 
number    is    recorded    together    with    a 
note    giving    a    reference    to    the    plans 
and   specifications   used   in   building   the 
motor.     Therefore,  if  the  serial  number 
is   known,   the    factory   records   can   be 
used  to  determine  all  details  of  the  mo- 
tor   construction.       In     this     sense     the 
statement  is  true.     In  the  sense  that  the 
numbers    form    part   of    a    code    which 
gives   winding   details,   the   statement   is 
totally  incorrect.  s.  H. 

2031— Starting  Frequency  Changer 
Sets — Kindly  give  me  correct  infor- 
mation for  starting  up  a  440  volt,  60 
to  120  cycle  induction  type  frequency 
changer  set.  I  presume  the  proper 
method  is  to  run  the  changer  as  a  mo- 
tor first  by  short-circuiting  the  col- 
lector rings,  to  see  in  which  direction 
it  will  run,  then  try  out  the  motor 
to  see  if  it  runs  in  the  opposite  di- 
rection. J.  p.  (ind.) 

The  presumption  is  correct.  Start  the 
slip  ring  machine  alone — by  short-cir- 
cuiting the  rings  and  connecting  to  the 
line,  and  observe  the  direction  of  rota- 
tion. Then  see  that  the  driving  motor 
drives  the  slip  ring  machine  in  the  op- 
posite direction,  with  secondary  open. 
H.  s.  s. 


CORRECTION 


2029— Magnetic  Brakes — Why  are  the 
coils  in  alternating-current  magnetic 
brakes  wound  in  two  equal  sections? 

G.    W.    S.     (cAU) 


In  the  Journal  for  July  1921,  p.  294 
the  cuts  for  Figs.  4  and  s  should  be 
interchanged. 


38o 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  8 


THE 
ELECTRIC 
JOURNAL 


The    purpose    of    this    Bection    is    to    present 

accepted  pr»ctic»l  methods  used  by  operating 

companies    throughout    the    country 


The   CO -operation   of  all   those   interested    i:: 

operating  and  maintaining  railway  equipment 

is    invited.      Address    R.    O.    D.    Editor. 


AUGUST 
1921 


Tinning  Malleable  Iron  Bearing  Shells 


Many  railway  motors  have  malleable  iron  shells  lined  with 
babbitt  on  both  armature  and  axle  bearings.  This  condition 
applies  more  generally  to  the  older  type  of  railway  motors,  as 
in  the  more  modern  motors,  bronze  armature  bearings  lined  with 
babbitt  and  bronze  axle  bearings  tinned  have  been  largely  adopt- 
ed as  standard.  This  change  has  been  brought  about  by  the  cam- 
paign for  the  light  weight  motors,  as  the  bronze  bearing  can  be 
made  with  a  thinner  shell,  thus  smaller  size,  than  a  malleable 
iron  bearing  shell  made  for  the  same  size  shaft  or  axle.  In  the 
case  of  bearings  made  for  an  axle  diameter  less  than  standard, 
which  necessarily  means  a  heavier  shell,  malleable  iron  bearings 
are  quite  often  used  on  the  modem  motors. 

LOOSE    BABBITT    LINING 

The  common  practice  in  connection  with  all  iron  bearing 
shells  is  to  provide  the  babbitt  seat  of  the  shell  with  anchors 
to  hold  the  babbitt  in  place.  These  anchors  usually  take  the  form 
of  cored  holes  enlarged  at  the  bottom,  and  plain  or  dovetailed 
cored  grooves.  In  some  cases,  these  anchors  in  the  form  of  holes 
or  groves,  are  machined  in  the  shell.  A  few  operators  have  dnll- 
ed  anchor  holes  through  the  shells  and  countersunk  the  outer 
ends  of  the  hole,  which  is  reported  to  prevent  babbitt  from 
breaking  away  from  the  shell. 

It  is  an  accepted  fact  that  this  type  of  bearing  gives  more 
or  less  trouble  in  service,  due  to  the  babbitt  becoming  loose  and 
breaking  away  from  the  shell.  This  is  largely  due  to  some  of  the 
following  reasons : 

I — Inferior  grade  of  babbitt. 

2— Incorrect  heating  and  pouring  temperature  of  the  metal. 

3— Mandrels  and  shells  not  properly  heated. 

4— Lack  of  skill  in  babbitting. 

Bearings  that  have  been  made  with  all  of  the  above  condi- 
tions kept  just  right  have  been  known  to  last  a  number  of  years 
in  service  without  giving  any  trouble.  On  the  other  hand,  where 
the  conditions  of  babbitting  are  questionable,  and  operating  con- 
ditions severe,  the  babbitt  lining  of  bearings  of  this  type  soon 
pounds  loose,  and  with  oil  working  in  between  the  babbitt, 
and  the  iron  shell  they  rapidly  deteriorate  and  must  be  replaced. 

TINNING    MALLEABLE    lEON    SHELLS 

As  very  little  trouble  is  experienced  with  the  babbitt  lining 
breaking  away  from  properly  tinned  and  babbitted  bronze  bear- 
ing shells,  a  method  of  tinning  malleable  iron  shells  has  been 
worked  up,  which  has  all  the  indications  of  being  very  satis- 
factorj'  in  ser\'ice.  This  method  is  based  upon  and  is  similar  to  a 
method  used  successfully  for  the  past  several  years  in  tinning 
wrought  iron  pipe  shells  which  are  lined  with  babbitt  metal,  and 
used  for  bearings  on  industrial  motors.  The  equipment  and  gen- 
eral arrangement  of  dipping  tanks  necessary  to  do  this  work 
are  shown  in  Fig.  i.  This  method  also  applies  to  cast  steel  bear- 
ing shells. 

CAST  lEON   SHELLS 

Cast  iron  can  be  tinned  by  this  method  by  reducing  the  tem- 
perature of  the  tinning  alloy  to  a  point  where  the  hot  metal  will 
just  run  off  the  shell  when  taken  from  the  tinning  pot  When 
cast  iron  shells  are  properly  tinned,  they  will  have  a  nice  bnght 
finish  and  look  good,  but  in  babbitting,  the  metal  will  not  stick 
to  the  tinned  surface  very  tight.  It  will  give  a  much  better  job 
than  when  not  tinned  at  all,  but  not  neariy  so  good  a  job  as 
obtained  on  malleable  iron  or  steel  shells. 

CLEANING  AND  PICKLING 

If  the  bearing  had  been  in  service,  remove  the  old  babbitt, 
oil  and  dirt  by  burning.  Allow  the  bearing  to  cool  after  cleaning 
and  then  pickle  the  shell  for  about  lo  to  15  minutes  in  a  solu- 
tion made  up  of  one  part  sulphuric  acid  and  ten  parts  of  water. 
If  this  solution  is  heated,  the  time  of  pickling  can  be  cut  down 
to  five  minutes.  Remove  the  shell  from  the  pickling  bath  and 
rinse  in  clean  water,  preferably  running  water;  othen,yise,  the 
water  will  soon  become  a  weak  solution  of  s'llphuric  acid. 

FLirXING  AND   TINNING 

After  the  shells  have  been  pickled,  they  are  dipped  (either 
wet  or  dry)  in  a  flux  of  zinc  chloride.  This  flux  is  a  saturated 
solution  of  zinc  in  hydrochloric  (commonly  known  as  muriatic) 


acid,  which  is  made  by  adding  zinc  to  the  acid  until  it  will  not  " 
dissolve  any  more.  After  being  allowed  to  drain  until  the  surplus 
flux  has  run  off,  but  while  still  wet,  dip  in  the  tinning  alloy  which 
should  be  half  and  half  solder.  The  temperature  of  the  tinning 
alloy  should  be  maintained  between  410  and  440  degrees  C  (770 
to  824  degrees  F.)  and  the  shell,  in  tinning,  should  be  brought 
approximately  to  the  same  temperature  .Remove  the  shell  from 
the  pot  and  brush  with  a  stiff  brush  to  remove  excess  solder. 

BABBITTING 

The  tinned  shells  should  be  babbitted  immediately  after 
the  tinning  operation.  When  this  is  done,  no  additional  pre- 
heating of  the  shell  is  required.  If  the  shell  is  not  babbitted  im- 
mediately after  tinning,  it  should  be  dipped  in  the  tinning  pot 
again  just  before  babbitting.  For  details  in  connection  with  bab- 
bitting, see  R.  O.  D.  for  Oct.  igi6.  The  most  important  points 
to  be  given  special  attention  while  doing  this  work  are  as 
follows : — 

I — Tin  bearings  in  half  and  half  solder,  and  not  in  the 
regular  babbitt  metal. 

2 — Temperature  of  tinning  alloy  410  to  440  degrees  C. 

3 — Temperature  of  mandrel  100  to  150  degrees  C. 


FIG    I — A — SULPHUWC   ACID    PICKLING    SOLUTION.;    B — CLEAN    RUN- 
ING  water;   C — ZINC  CHLORIDE  SOLUTION;  D— TIN- 
NING   POT    WITH    SHIELD 

4 — Do  not  use  any  wet  mud  to  close  up  windows,  etc,,  as 

this  tends  to  chill  the  bearing. 
5— Pouring  temperature  of  babbitt  460  to  482  degrees  C 

PEECAUTIONS 

In  connection  with  doing  this  work,  the  follovring  points 
should  be  carefully  noted: — 

I— The  workman  should  stand  aside  when  dipping  the  wet 
shell  in  the  tinning  solution,  to  avoid  being  burned  by 
splashing  metal.  ,    ,       .     . 

2— A  metal  shield  should  be  placed  around  the  tinning  pot 
to  protect  the  workman. 

3— Shells  that  are  not  well  tinned  should  be  placed  in  the 
pickling  bath  till  clean  and  retinned.         _  , 

4— Do  not  brush  or  attempt  to  swab  the  inside  of  bearing 
shells  after  tinning,  as  a  slight  trace  of  grease  will  keep 
the  babbitt  from  sticking  to  the  shell. 

5— Exhaust  hoods  or  a  canopy  should  be  provided  over  tne 
acid  bath,  to  carry  ofT  the  poisonous  fumes. 

6— To  keep  the  babbitt  from  sticking  to  the  window  and  the 
outside  of  the  shell,  coat  these  parts  with  a  red  clay  wash. 

7 Clean  out  the  pickling  tank  occasionally.  This  will  de- 
pend upon  the  rqgularitj-  of  the  work.  It  the  tank  is 
used  continuously,  it  should  be  cleaned  out  every  two 
weeks.  J-  S-  Dean 


The  Electric  Journal 


VOL.  XVIII 


September.  1921 


NO.9 


The  Association  of  Iron  and  Steel 
Electrical  Engineers 

ERNEST  S.  JEFFERIES 

I'rosident,  A.   1.  &  S.   I-:.  K. 

When  one  carefully  surveys  the  growth  of  the 
iron  and  steel  industr}',  and  analyzes  the  many  factors 
which  have  contributed  to  its  phenomenal  growth,  he 
must  be  impressed  by  the  important  place  which 
electricity  has  taken.  I'robably  all  industries 
have  been  affected  through  the  rapid  growth 
and  development  of  the 
electrical  industry,  and 
the  extensive  application 
which  is  following  has 
found  a  fertile  field  in  the 
steel  industry.  We  are 
indebted  to  those  whose 
research  has  contributed 
to  this  rapid  development. 
The  application  of 
electric  motors  to  steel 
mill  drives,  from  the 
smallest  auxiliaries  to  the 
main  rolls,  has  progressed 
until  motor  drive  is  prac- 
tically taken  for  granted 
in  all  new  installations 
and  is  gradually  replacing 
other  forms  in  the  older 
plants.  f)ne  of  the  inter- 
esting features  of  this  de- 
velopment is  the  increas- 
ing use  of  automatic  con- 
trol, which  relieves  the  op- 
erator of  any  responsibil- 
ity in  obtaining  proper  se- 
cpience  o  f  operations, 
thereby  |>ermitting  more 
rapid  and  s  m  o  o  t  h  e  r 
operation. 

Another  interesting 
development  is  shown  in 
the  increasing  use  of  elec- 
tricity for  producing  heat. 
Applications  of  electric  furnaces  are  increasing  rapidly 
and  results  are  being  produced  which  in  many  cases 
are  so  far  superior  to  those  obtainable  by  any  other 
method  as  to  make  the  question  of  cost  of  secondary 
consideration.  No  less  important  are  the  smaller 
applications,  such  as  furnaces  for  heat  treatment  of 
steels,  melting  babbitt,  etc.,  where  the  absolute  and 
automatic  temperature  control,  quick  results,  and  free- 
dom  from   deleterious  gases  are  of  prime  importance. 


ERNEST  S. 

Electrical 
Steel   Company 


In  the  i)ast,  it  was  not  necessary  that  the  steel  mill 
organizations  carry  an  electrical  engineering  staff,  but 
due  to  the  above  developments,  each  year  it  has  become 
a  greater  necessity  that  a  competent  electrical  engineer 
be  part  of  the  steel  mill  organization.     It  is  now  neces- 
>ar\-    to    carry   a    well    organized   electrical    department 
to    engineer   the    new    developments,    to   design,    install 
and    operate    the   ever   increasing   variety   of   electrical 
appliances.     With   such  an   organization   back   of   him. 
the  electrical  engineer  of  today  has  a  responsibilitv  in- 
trusted      to       him       which       should       be       zealouslv 
guarded,    for    the    interest 
and    thought   he   gi\es   this 
trust   will    determine    what 
the  future  will  bring  forth. 
If  the  proper  time  is  gi\en 
to  thoroughness  in  analyz- 
ing electrical  needs  of  his 
plant  today,  the  conditions 
existing     tomorrow     w  i  1  1 
place  his    department    and 
himself     foremost     in    the 
plant      engineering     work. 
In    the   last    few   years    we 
have   seen   a   greater  num- 
ber of  men  advanced  from 
the    electrical      department 
to    still    more     responsible 
jinsitions    than  before,  and 
it     should     be     the     daily 
thought    of  every    member 
of  the  Association  of  Iron 
&    Steel     Electrical     Engi- 
neers  so   to  apply   himself 
to  the  need  of  the  day  that 
he   will   be   the  man   to  be 
promoted. 

There  is  but  one  engi- 
neering society  today  de- 
voting its  entire  work  to 
the  iron  and  steel  indus- 
try. Holding  this  position, 
the  Association  of  Iron  & 
Steel  Electrical  Engineers 
is  laying  out  its  work 
so  that  its  papers  and  meetings  will  be  of  interest  to  the 
managers,  mechanical  and  electrical  engineers,  as  well 
as  the  maintenance  and  operating  departments.  It  is 
gratifying  to  note  an  e\er  increasing  number  of  steel 
mill  officials  in  our  membership,  and  their  interest  and 
attendance  at  our  meetings.  Our  purpose  is  to  cover 
steel  mill  problems  so  thoroughly  as  to  make  unneces- 
sary the  existence  of  any  other  engineering  society  de- 
voting its  entire  time  to  this  subject. 


JEFFERIES 
Eng-inecr 
of  Canada,   Ltd 


-,82 


THE    ELECTRIC    JOURNAL 


Vol.  Will,  No.  9 


The  Function  and  Limitations  of 
Insulation 

B.  G.  LAMME 

Cliicf  Engineer, 
Westinghouse  Electric  &  Mfg'.  Co. 

Tc>  THE  uninitiated,  an  electrical  machine  is  a 
source  of  wonder — a  mystery.  What  are  ap- 
parenth'  inert  wires,  attached  to  a  mass  of  metal, 
produce  rotation  through  the  action  of  invisible  forces. 
\  remendous  turning  effort  results  from  an  invisible 
something  called  magnetism,  which  has  some  relation 
to  a  multii^licity  of  wires  arranged  in  some  peculiar 
manner  to  form  what  are  called  armature  and  field 
windings. 

To  the  initiated,  the  in\isible  forces  of  niagnelisn: 
producing  rotation  are  not  a  .source  of  wonder,  usually 
because  of  familiarity  with  the  actions  taking  place 
and  a  knowledge  of  certain  fundamental  laws.  How- 
ever, to  those  who  know  most  about  the  actions  of  such 
electrical  machines,  there  is  still  one  source  of  increas-" 
ing  wonder  in  such  apparatus,  and  this  lies  in  what  is 
called  the  "insulation."  Here  is  something  that  has 
little  or  nothing  to  do  with  the  real  activities  of  the 
apparatus — its  functions  seem  to  be  mostly  of  a  nega- 
tive sort — and  yet  it  is  one  of  the  absolutely  necessary 
structural  components  of  the  electrical  machine.  It 
serves  simply  as  a  barrier  to  keep  the  electrical  current 
from  straying  from  certain  prescribed  paths.  Thi.< 
looks  simple  enough.  The  wonder  does  not  lie  in  the 
function  of  the  insulation  as  much  as  in  the  material 
itself,  for  structurally  it  is  made  up  of  about  as  un- 
niechanical  components  as  can  be  found.  This  faci 
is  not  due  to  ignorance  or  bad  judgment  of  the  design 
ers  of  such  apparatus,  but  lies  in  the  very  nature  of  iri- 
sulating  materials  themselves. 

Fundamentally,  insulating  materials  are  non-con- 
ductors— that  goes  without  saying.  Now,  it  so  ha!>- 
pens  that  metals,  or  materials  of  a  metallic  nature,  are 
fairly  good  conductors  of  electricity  and,  therefore, 
metallic  materials  are  forbidden  as  insulations.  On 
the  other  hand,  in  the  class  of  proper  insulations  are 
found  such  materials  as  varnishes,  gums,  waxes,  oils, 
artificial  fibrous  materials,  suth  as  papers,  cloths  antl 
.so-called  fibers,  many  of  which  are  in  themselves 
merely  mechanical  separators  rather  than  insulators. 
Also  there  are  a  few  mineral  insulators  such  as  as- 
bestos, mica,  etc.  and  various  porcelains,  lavas  and 
similar  materials,  many  of  which  in  their  usable  state 
represent  artificial  products.  Many  of  the  fibrous 
materials,  including  asbestos,  must  be  impregnated,  or 
filled,  with  gums,  oils,  etc.,  before  they  become  satis- 
factory insulators.  Looking  over  the  whole  list,  it 
seems  as  if  almost  anything  which  is  bad  fi'om  a  me- 
chanical standpoint,  is  in  the  class  of  insulators. 

To  make  the  situation  worse,  insulation,  being 
principally  a  barrier  to  confine  the  electrical  current, 
must  in  many  cases  be  applied  in  such  a  wa}-  that  mo'e 


or  less  rtexibility  is  required  in  its  application  and  use. 
This  is  especially  true  in  electrical  machinery.  The 
msulation,  being  a  covering  material  in  many  cases, 
is  naturally  more  or  less  exposed,  whereas,  from  its 
own  mechanical  nature  it  should  be  well  protected. 
Moreover  it  is  subjected  to  all  kinds  of  heating  and 
cooling,  sometimes  of  a  rapid  nature,  tending  to  pro- 
duce cracks  and  flaws  in  the  material  itself,  or  in 
some  of  its  elements,  wdiich  may  prove  more  or  less 
fatal  to  its  insulating  cjualities. 

Back  of  all  this  lies  the  fact  that  in  spite  of  the 
years  of  effort  which  have  been  expended  on  insulat- 
ing materials,  we  know  as  yet  practically  nothing 
about  their  real  nature  and  characteristics.  In  fact,  we 
do  not  even  know  why  some  materials  are  insulators 
and  others  are  not.  We  simply  have  at  hand  certam 
facts  based  upon  e.xperience,  and  the  art  of  insulation 
as  it  stands  today  is  simply  built  u|)  (jn  such  facts. 
In  laboratory  and  shop  tests,  two  insulating  materials 
may  show  up  equally  well  in  every  way,  as  far  as  can 
be  determined,  and  yet,  under  similar  operating  con- 
ditions, one  may  deteriorate  rapidly,  while  the  other 
may  remain  as  good  as  new.  Why  ?  Nobody  knows. 
To  rejieat,  in  most  cases,  all  we  have  is  experience 
and  a  very  limited  range  of  experience  at  that,  due  to 
the  fact  that,  for  safety,  we  have  had  to  keep 
closely  to  known  methods  and  materials.  If  it  takes 
from  one  to  five  years  of  operation  to  determine  the 
commercial  durability  of  certain  insulating  materials, 
and  combinations  of  materials,  naturally,  the  designers 
dare  not  take  undue  risks  with  new  insulations  or  new 
methods  of  using  them  for,  if  a  material  should  prove 
defective  after  a  couple  of  years,  the  manufacturer 
might  have  an  avalanche  of  trouble  on  his  hands. 

Nevertheless,  it  must  be  understood  that  the  in- 
sulating art  never  has  been,  in  any  way,  at  a  stand- 
still. A  vast  amount  of  research  and  experiment  has 
been  carried  on  by  the  electrical  manufacturers.  ;il- 
most  since  the  beginning  of  the  electrical  art,  to  de- 
termine the  fundamental  characteristics  of  insulating 
materials ;  for  the  whole  success  of  electrical  apparatus 
is  dependent  upon  such  materials. 

.\  manufacturer  builds  up  a  certain  method  of  in- 
sulating, based  upon  long  experience.  The  results 
prove  satisfactory  but,  during  many  years  of  practice, 
little  changes  creep  in,  none  of  them  apparently  of 
more  than  very  minor  importance,  and  each  one  ap- 
parently a  step  in  the  direction  of  better  results.  In 
some  cases  the  changes  may  be  so  small  that  it  is  dif- 
ficult even  to  perceive  them.  However,  after  a  while, 
something  goes  wrong,  the  results  apparently  are  not 
as  good  as  formerly,  and  the  puzzle  is  then  to  deter- 
mine just  what  has  happened.  Each  minor  change 
is  gone  over  in  detail.  Eventually  the  trouble  is  over- 
come, but  it  must  be  admitted  that  in  some  case  the  real 
cause  is  seen  only  dimly. 

This  is  not  a  criticism  of  the  designers  or  re- 
search  men,   but   is   simjily   intended   to   show   that,   in 


September,  1921 


THE    ELECTRIC   JOURNAL 


383 


insulations,  we  are  dealing,  to  a  very  large  extent,  with 
the  unknown,  and  that  success  in  the  art  of  insulation 
is  built  up  largely  upon  practical  experience.  From 
this  viewpoint  the  motto  of  the  designer  well  could  be 
that  "All  insulations  are  guilty  until  proved  innocent." 
Considering  the  difficulties  of  the  problem,  it  u 
astounding,  to  those  well  versed  in  the  art,  that  such 
remarkably  good  practical  results  have  been  obtained 
and  maintained.  Advances  are  being  made  in  the  art 
of  insulation  and  they  have  been  made  continuously 
since  the  earliest  days.  With  each  step  forward 
there  have  been  mistakes,  until  experience  has  been  ob- 
tained;  and  with  the  remedy  of  such  mistakes,  there 
has  been  growth  through  new  knowledge  of  the  sub- 
ject. Increasing  knowledge  of  the  real  nature  and  the 
real  weaknesses  of  insulating  materials  on  the  part 
of  the  users  of  electrical  apparatus  has  been  of  vast 
help  in  this  problem.  With  such  knowledge  comes  ap- 
preciation of  the  limitations,  with  consequent  better 
care  and  maintenance.  This  is  a  subject  "where  ig- 
norance is  bliss"  and  where  those  who  know  the  least 
about  it  can  make  the  biggest  promises.  But  the 
writer  fully  believes,  and  has  believed  for  years,  that 
the  more  the  user  of  electrical  apparatus  knows  about 
the  nature  and  weaknesses  of  all  insulating  material.^, 
the  better  he  is  prepared  to  protect  this  weakest  pa't 
of  all  electrical  apparatus. 

Electrical   Developments   in    the    Iron 
and  Steel  Industry 

R.  B.  GERHARDT 

Electrical  Supt.,  Bethlehem  Steel   Co., 
Director,  Assoc.  Iron  &  Steel  Electrical  Engineers 

ELECTRICAL  development  in  the  iron  and  steel 
industry  during  the  past  year  has  been  more  or 
less  restricted  to  smaller  items  which  entailed 
light  expenditures  and  affected  a  maximum  of  econo- 
my, due  to  the  greatly  depressed  business  conditions. 
However,  quite  a  few  electric  main  mill  drive  equip- 
ments have  been  built  or  put  into,  operation.  In  this 
country  the  replacement  of  steam  engines  on  the  Lacka- 
wanna rail  mill  and  the  Steelton  blooming  mill  of  the 
Bethlehem  Steel  Corporation  by  electric  reversing  mo- 
tor drives  were  noteworthy  events.  Two  revers- 
ing drives,  one  a  double  and  the  other  a  single  unit 
motor,  were  shipped  to  India  for  the  Tata  Iron  &  Steel 
Company.  A  total  of  thirty-six  additional  mill  motor 
drives  ranging  in  size  from  5750  down  to  300  horse- 
power were  built  or  completed  during  the  past  year  by 
American  manufacturers,  and  six  of  these  went  to  for- 
eign countries.  Thirteen  of  the  thirty-six  were  varia- 
ble speed  alternating-current  equipments. 

An  item  of  considerable  interest  in  connection 
with  electrical  main  roll  drives  has  been  the  rearrange- 
ment of  control,  making  possible  a  reduction  in  the  op- 
erating force  on  these  mills.  Blooming  mills  are  now 
being  operated  with  two  instead  of  three  men  in  the 
pulpit,  and  as  many  as  two  operators   have    been    dis- 


placed on  mills  like  a  reversing  universal  plate  mill. 

For  the  steel  plant  power  house,  the  gas  engine 
is  still  a  prime  mover  to  be  seriously  considered,  is 
thermal  efficiencies  equal  or  better  than  those  of 
modern  steam  units  are  easily  obtainable,  and  the  pres- 
ent development  makes  it  possible  to  obtain  in  a  single 
unit  a  capacity  of  4000  k\v,  which  is  considerably  more 
than  that  obtained  with  the  older  units.  It  has  also 
been  successfully  demonstrated  that  a  gas  engine  in- 
stallation can  be  operated  from  a  single  furnace  in 
blast  by  making  use  of  a  gas  holder  of  moderate  size 
and  certain  automatic  regulating  valves  in  connection 
with  a  gasometer  for  its  manipulation. 

An  investigation  of  the  possibilities  of  interconnec- 
tion between  the  steel  mills  and  the  large  central  sta- 
tions reveals  the  fact  that  in  most  of  the  larger  steel 
plants  25  cycles  is  the  standard  frequency  whereas  cen- 
tral station  tendency  is  toward  60  cycles.  For  tying 
together  such  systems,  frequency  changers  up  to  i 
capacity  of  7000  kv-a  are  being  built.  Such  a  set  will 
shortly  tie  the  25  cycle  plant  of  the  Tennessee  Coal, 
Iron  &  Railroad  Company  with  the  60  cycle  system  of 
the  Alabama  Power  Company. 

The  use  of  electrical  energy  as  a  heating  agent  is 
lapidly  increasing  in  the  steel  plant.  Electrically 
heated  tin  pots,  babbitt  pots,  drying  ovens,  ovens  for 
heat  treating  and  enameling  are  some  of  the  princi- 
pal applications,  while  special  work  is  being  done  on 
the  development  of  equipment  for  electrical  heating  of 
steels  for  the  manufacture  of  bolts,  rivets  and  spikes. 

An  event  of  considerable  interest  in  electric  fur- 
nace application  was  the  tapping  of  the  first  heats  from 
the  two  40  ton  three-phase  Heroult  furnaces  of  the 
Government  armor  plant  at  Charleston,  West  Virginia. 
Molten  steel  from  the  basic  open  hearth  furnaces  is 
delivered  to  these  furnaces  where  the  retining  is  com- 
pleted, resulting  in  the  production  of  a  very  high  class 
steel.  At  the  Pittsfield  plant  of  the  General  Electric 
Company  there  was  completed  recently  a  run  on  an 
induction  furnace  when  the  555th  heat  was  poured. 
The  service  is  particularly  hard,  as  high  silicon  steel 
is  melted  on  a  basic  lining  with  excellent  results. 

There  has  probably  been  more  development  in  the 
control  field  during  the  past  year  than  in  any  other  sin- 
gle line  of  apparatus.  All  of  this  work  tends  toward 
the  simplification  of  magnetic  control,  the  standardiza- 
tion of  parts,  the  reliability  of  operation,  and  the  life 
of  wearing  parts,  contacts,' and  arc  chutes. 

An  item  under  keen  investigation  in  the  steel  plant, 
which  as  yet  has  hardly  reached  the  development  stage, 
is  the  electrification  of  the  plant  railroad  yards,  with 
a  view  toward  eliminating  steam  locomotives  for  trans- 
portation. This  probably  presents  a  larger  field  for 
development  effort  than  any  other  single  item  in  the 
plant,  as  it  is  felt  that  railroad  electrification  has  not 
kept  pace  with  mill  electrification. 

The  greatly  reduced  operations  in  the  steel  indus- 
try of  to-day  make  it  necessary  to  cut  all  costs  of  pro- 


384 


THE    ELECTRIC   JOURNAL 


\o\.  X\"III,  No.  9 


duction  to  a  minimum,  and  this  field  of  developmenr 
has  thus  the  greatest  stimulus  and  should  go  attached 
with   un|)recedented  effort. 

Dependable  Driving  Equipment 

G.  E.  STOLIZ 

Steel  Mill  Engineer, 
Westinghouse  Electric  &  Mfg.  Co. 

IN  THIi  electrification  of  the  main  rolls  of  a  large 
steel  mill,  the  reliability,  cost  of  maintenance  and 
life  of  the  electrical  equipment  are  important 
items  for  consideration.  The.se  items  are  all  discussed 
in  an  article  in  this  issue  of  the  Journal  by  Mr.  W.  .S. 
Hall,  in  his  description  of  the  first  reversing  mill  equip- 
ment installed  in  this  country.  He  also  outlines  the 
advantages  obtained  by  electrification  which  were  ivA 
cai)ilalized  when  the  decision  was  made  to  drive  this 
mill  by  electric  rather  than  by  steam  power. 

This  equipment,  which  re])resented  an  entire'y 
new  venture,  has  operated  fourteen  years  with  delays 
which,  during  the  last  few  years,  are  almost  negligi- 
ble— in  fact  during  the  thirteenth  year  no  delays  what- 
ever were  charged  against  the  equipment.  Ha  re- 
versing engine  had  been  installed  on  this  mill,  it  would 
now  be  considered  out-of-date,  both  from  the  point  of 
view  of  economy  and  maintenance,  but  today  this  nut- 
tor  drive  is  just  as  economical  as  the  day  it  was  in- 
stalled and,  instead  of  an  increasing  number  of  break- 
downs, an  interruption  from  the  dri\ing  etpiipment  is 
almost  a  thing  of  the  past. 

.Although  this  first  equipment  has  o[>erated  during 
the  entire  period  with  delays  amounting  to  but  one-half 
of  one  ])ercent,  this  is  not  necessarily  an  exceptionally 
good  record.  Ry  i^eferring  to  the  Proceedings  of  the 
Association  of  Iron  &  Steel  Electrical  Engineers,  it 
will  be  noted  that  the  first  reversing  blooming  mill  mo- 
tor equipment  driving  the  34  inch  mill  at  the  Steel 
Company  of  Canada  operated  four  and  one  half  years 
during  the  war  period  with  delays  amounting  to  0.04 
jiercent. 

Recently  the  chief  engineer  of  one  of  the  large 
mill  manufacturers  made  the  statement  that  he  would 
recommend  electric  drive  in  preference  to  engine  drive, 
even  assuming  that  the  cost  of  operation  with  the  elec- 
tric motor  was  slightly  in  e.xcess  of  that  with  the 
engine.  He  has  studied  the  situation  sufficiently  to 
evaluate  those  advantages  of  the  electric  drive  which 
are  more  or  less  intangible. 

The  introduction  of  electric  drive  on  our  rolling 
mills  is  going  to  establish  a  new  idea  of  service  which 
rolling  mill  engineers  and  superintendents  will  expect 
from  their  equipment,  li  motor  drive  can  operate 
with  i)ractically  no  delay,  interruptions  caused  by  ihc 
mill  machinery  will  be  more  noticeable,  and  we  can  ex- 
pect that  higher  grade  mill  machinery  will  be  installed 
in  the  fiitme. 

The  fact  that  the  equipment  described  In-  .Mr.  Hall 
has  remained  almost  intact,  particularly  the  bearings. 
very  clearlv  indicates  that  the  inherent  characteristics 


of  electric  drive  make  it  better  adapted  to  rolling  mill 
service  than  the  engines  which  it  is  superseding. 

The  most  remarkable  statement  in  Mr.  Hall's  arti- 
cle is  that  "after  fifteen  years  of  service  no  definite 
conclusion  can  be  formed  as  to  the  life  of  a  winding  on 
this  class  of  equi]iment." 

Mechanical  Maintenance  of  Mill 
Equipment 

G.  M.  EATON 

Chief   Mechanical   Engineer, 
Westinchouse  Electric  &  Mfg.  Co. 

RFXIARILITY  is  the  mill  operator's  yardstick 
for  measuring  his  ecpiipment.  F"requent  fail- 
ure of  a  part  on  which  is  dependent  the  .steady 
flow  of  steel  through  the  qiill  dooms  the  offender  to  the 
scrap  heap  as  soon  as  a  more  reliable  replacement  is 
feasible. 

Steel  is  produced  by  men  and  machines,  and  the 
reliability  of  the  machines  is  a  direct  function  of  the 
abilit)-  and  reliability  of  the  men.  The  best  mill  oper- 
ators give  their  equipment  a  chance  by  proper  installa- 
tion and  the  exercise  of  eternal  vigilance  in  heading  otT 
deterioration.  Good  equipment  badly  installed  loses 
much  of  its  inherent  reliability. 

The  production  of  steel  imposes  such  drastic 
rough  and  tumble  service  on  etiuipment,  that  it  h  i^ 
seemed  almost  impossible  to  make  mill  apparatus  that 
will  run  over  long  ])eriods  of  time  without  failure. 
The  continuation  of  failures  after  jirolonged  endeavor 
to  secure  their  complete  elimination  has  caused  the 
growth  of  a  conviction  that  all  mill  equipment  is  heir 
to  trouble  and,  in  some  instances,  a  careless  habit  has 
grown  up,  resulting  in  more  or  less  condoning  failures. 

The  introduction  of  electrical  equipment  has  elim- 
inated some  of  the  ills  heretofore  fundamentally  as- 
sociated with  other  forms  of  drive.  Electric  drive,  how- 
ever, retains  certain  mechanical  features  which  will 
give  trouble,  unless  proper  precautions  are  taken.  There 
is  a  nebulous  region  between  horse  sense  precaution 
and  finicky  refinement.  Messrs.  Pruger  and  Deesz,  in 
this  issue  of  the  Joi-rnal,  deal  constructively  with  the 
practical  side  of  trouble  elimination  by  the  removal  of 
contributary  causes.  The  article  brings  out  strongl> 
that  a  flexible  cou])ling,  in.stead  of  a  cure-all  for  care- 
less workmanship,  is  a  device  which  assists  in  carin;; 
for  errors  and  vibrations  which  are  fundamentally  un- 
avoidable. It  emjihasizes  the  necessity  of  keeping  all 
parts  in  i)roper  balance,  and  shows  that  tribulation 
treads  hard  on  the  heels  of  neglect.  While  bringing 
out  that  most  of  the  ills  of  mill  equipment  may  be 
traced  back  to  the  fundamentals  of  alignment  and  bal- 
ance, the  central  thought  may  be  stated  in  a  phrase- - 
"and  the  greatest  of  these  is  alignment." 

Mill  operators  will  find  that  study  and  practice 
along  the  lines  suggested  in  this  article  will  help  es- 
tablish the  boundaries  between  fundamental  require- 
ments and  useless  frills,  and  will  show  where  concen- 
trated attention  on  their  part  will  minimize  failures. 


^bi 


Ooi>J) 


C.  VV.  KINCAUJ 

Motor  Engineering  l-^ept., 
Westinghouse  Electric  &  Mfg'.  Co. 


INDUCTION  motors  are  primarily  constant  speed 
motors  and  have  been  applied  principally  on  loads 
which  require  rather  flat  speed  regulation  and 
only  one  speed.  Occasions  arise,  however,  especially 
in  connection  with  large  steel  mill  motors,  where  ad- 
justable speed  is  desired,  and  this  can  be  secured  by 
the  use  of  auxiliary  commutator  machines  which  allow 
the  main  motor  to  operate  at  other  than  its  normal  syn- 
chronous speed,  as  determined  by  the  frequency  of 
supply  and  the  numbers  of  poles. 

In  a  direct-current  motor,  the  speed  can  be 
\aried  by  changing  the  field  strength  by  means  of  a 
field  rheostat.  When  the  speed  changes,  the  frequencv 
in  the  rotor  core  and  coils  also  changes  in  direct  pro- 
portion to  the  speed,  the  same  as  in  any  alternator,  but 
this  alternating  current  is  converted  into  direct  cur- 
rent by  the  commutator  and  brushes  so  that  a  change 
in  s[)eed  means  only  a  change  in  voltage. 

In  an  induction  motor  there  is  no  field  circuit  to 
\ar3%  since  the  field  is  supplied  by  the  same  winding 
which  carries  the  main  working  current,  so  that  this 
method  is  not  available  for  speed  changing.  The  line 
fi'cquency  is  usually  supplied  to  the  stator  and  pro- 
duces a  rotating  field  whose  speed  in  the  air-gap  is  pro- 
portional to  the  frequency  and  inversely  to  the  number 

.        ,         .  '     /  X  i.'o 

of    poles,    I.e.,    r.p.m.    =    -.     This    rotating 

P 
magnetic  field  will  generate,  in  a  rotor  which  is  wound 
for  the  same  number  of  poles  as  the  stator,  a  variable 
voltage  and  frequency,  depending  on  whether  the  rotor 
is  stationary  or  rotating. 

If  the  rotor  is  stationary,  the  flux  cuts  the  rotor 
conductors  at  primary  frequency  and,  as  the  voltage 
generated  is  proportional  to  the  speed  of  cutting  the 
rotor  conductors,  the  secondary  voltage  will  be  pro- 
portional to  the  ratio  of  turns  on  stator  and  rotor,  Fig. 
I.  If  the  rotor  is  running  in  the  same  direction  as 
the  stator  field  but  only  one-half  as  fast,  the  primar_\- 
fiux  is  cutting  the  rotor  conductors  at  one-half  the 
speed  it  was  before  and  will  generate  only  one-half 
the  frequency  and  one-half  the  \-oltage.  At  syn- 
chronous speed  the  rotor  is  turning  at  the  same  speed 
as  the  field.  The  primary  flux  does  not  cut  the  rotor 
conductors  and  so  generates  no  frequency  or  voltage. 

At  speeds  above  synchronism,  the  rotor  again  cuts 
the  primary  field  and  induces  a  frequency  and  a  volt- 
age which  increase  in  direct  proportion  to  the  speed 
aboN-e  synchronism,  but  in  this  case,  the  rotor  conduc- 
tors are  going  faster  than  the  field,  while  before,  the 
field  was  faster  than  the  conductors,  so  that  the  direc- 
tion of  the  induced  voltage  is  reversed. 

The  toripie  in  an  induction  motor  is  produced  by 


the  reaction  of  the  primary  field  on  the  ampere-turns 

of  the  rotor.     Since  the  primary  field  is  constant,  being 

supplied  by  a  constant  voltage,  each  value  of  current 

then  corresponds  to  a  definite  value  of  torque.     This 

value  of  current  will  not  change  when  only  the  speed  is 

changed,  but  the  voltage  on  the  rotor  will  change  as 

shown  above. 

With  varying  speed  at  constant  torque  the  output, 

torque  X  f.p.m. 
which  is  equal  to  - 


will  be  proportional 


5^50 

to  the  speed,  i.e.,  at  one-half  si)eed,  one-half  full  load 
in  horse-power ;  at  full  speed,  full  load  ;  at  one  and  one- 
half  speed,  one  and  one-half  load.  Since  a  constant 
tor(|ue  requires  a  constant  current  input  at  constant 
\oltage,  the  power  input  to  the  primary  corresponding 
to  full-load  torc[ue  is  constant  at  the  full  load  value, 
regardless  of  speed,  while  the  output  in  mechanical 
power  is  proportional  to  the  speed,  so  that  the  difier- 
ence  must  appear  as  electrical  power  at  the  collector 
rings. 

At  standstill,  the  output  in  mechanical  power  is 
zero,  S(j  that  the  entire  in])ut  must  appear  as  losses  in 
the  machine  and  electrical  output  from  the  rotor.  In 
this  case  the  motor  is  only  a  transformer.  As  the 
rotor  speeds  u]>,  the  motor  does  work  in  proportion  to 
the  product  of  torque  and  speed  and  only  the  re- 
mainder, which  is  proportional  to  the  difference  be- 
tween the  full  speed  and  the  given  speed  (known  as 
slip),  appears  at  the  collector  rings  as  electrical  energy. 
At  full  speed,  all  the  primary  injiut  (except  losses)  is 
given  out  as  mechanical  output  and  no  electrical  out- 
put is  available  at  the  collector  rings.  In  the  above, 
the  mechanical  output  has  been  the  difference  between 
the  primary  input  and  the  power  available  at  the  col- 
lector rings.  We  have  gradually  increased  the  :ne- 
chanical  output  by  decreasing  the  power  taken  from  the 
collector  rings  to  zero  and,  evidently,  to  obtain  any 
more  power,  we  must  make  this  quantity  less  than 
zero,  or  in  other  words,  take  negative  power  from,  or 
give  positive  power  to,  the  rotor.  If  this  is  done  the 
mechanical  power  becomes  the  sum  of  the  priniar\'  in- 
|iut  and  the  rotor  input,  increasing  as  the  priwer  to  the 
rotor  is  increased.  Since  the  rotor  current  is  fixed  for 
a  given  torque,  the  variation  in  power  must  be  made 
by  changes  in  the  value  and  direction  of  the  second- 
ary voltage. 

Therefore,  the  only  way  to  cause  an  induction 
motor  to  run  at  speeds  other  than  near  its  normal 
synchronous  speed,  is  to  supply  or  consume  a  variable 
voltage  at  the  collector  rings,  keeping  in  mind  also  that 
the  frequency  of  this  voltage  must  always  be  the  same 
as  supplied  by  the  rotor  of  the  main  motor. 


386 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


The  problem  then  resolves  itself  into  finding  a 
means  of  using  up  the  energy  which  appears  at  the 
collector  rings  below  synchronism  and  supplying  power 
to  the  rings  for  operation  above,  all  this  being  done 
automatically  with  changing  loads  and  speeds.  There 
are  various  ways  of  doing  this,  all  of  which  are  prac- 
tical and  can  be  used  for  steel  mill  service. 

The  Kramer  System  is  a  method  in  which  the 
variable  voltage,  variable  frequency  power  from  the 
collector  rings  is  converted  into  direct  current  by  using 
a  rotary  converter  in  the  rotor  circuit  of  the  main  mo- 
tor.    The  direct  current  so  produced  is  used  up  by  a 


These  sets  can  be  operated  above  synchronism  if 
means  are  provided  for  bringing  them  above,  and  in 
some  cases,  where  the  friction  load  is  light,  there  is  a 
possibility  of  getting  above  without  auxiliary'  means, 
merely  by  reversing  the  field  on  the  auxiliary  machine. 
When  operating  above,  the  lower  limit  is  approximately 
tour  to  five  percent  above  synchronism,  the  same  as 
for  below. 

The  Scherbius  System  is  so  devised  that  it  takes 
energ}-    direct    from   the    collector    rings   of   the   main 


Siandsl.ll  On.  H.K  Sprtd  Synchronous  Spmi  Four  Th„<li  Spcrf 

FIG.    I — SECOND.\RV   VOLT.AGE   AKD    FREQUENCY    AT   DIFFERENT   SPEEDS 


FIG.  3 — S(  HKM.\TU    I1IA(,RAM   l)F   KRAMF.R  SVSTE.M 


direct  current  machine  which  can  be  mounted  on  tlie 
main  motor  shaft  and  add  its  torque  to  the  main  motor 
torque,  thus  producing  a  constant  horse-power  set.  Fig. 
3,  or  the  direct  current  power  can  be  used  to  drive  a 
motor-generator  set  and  return  the  power  to  the  line, 
producing  a  constant  torque  set.  The  speed  is  varied 
by  changing  the  excitation  on  the  auxiliary  machine, 
which  produces  a  change  in  its  counter  e.m.f. 

This  system  has  its  principal  field  in  ranges  below 
the  synchronous  speed  of  the  main  motor,  since  the 
rotary  converter  fails  to  function  properly  when  the 
main  motor  approaches  its  normal  speed  and  the  volt- 
age and  frequency  fall  below  approximately  four  to 
five  percent  of  the  open  circuit  values. 


\l.LATION    OF    KK.VXn 


This  set  is  fairly  cheap,  as  the  main  motor  is  made 
with  a  normal  speed  which  is  the  highest  speed  re- 
quired by  the  mill  and  a  standard  rotary  converter  can 
usually  be  used  and  very  little  changes  are  necessary' 
for  the  auxiliary  direct  current  motor,  so  that  very 
little  development  is  required.  Besides  this,  all  the 
apparatus  is  familiar  to  operating  men  and  ever)'body 
knows  whei-e  to  look  for  trouble  if  any  occurs.  The 
only  objection  is  that,  in  case  the  auxiliary'  apparatus  is 
out  of  commission,  the  mill  when  operating  with  the 
motor  alone,  will  be  at  the  high  speed  where  some  sec- 
tions could  not  be  rolled  which  might  possibly  be  rolled 
if  the  motor  were  of  medium  speed. 


motor  and  converts  the  electrical  power  into  me- 
chanical power  in  one  auxiliary  motor.  This  motor  is 
a  polyphase  compensated  commutator  motor  and 
usually  drives  a  generator  which  can  be  synchronous 
or  induction  but  is  generally  induction.  This  scheme 
gives  a  constant  torque  set,  as  the  excess  power  is  re- 
turned to  the  line. 

The  commutator  motor  can  also  be  mounted  on  the 
.'ihaft  of  the  main  motor  in  which  case  it  makes  a  con- 
stant horse-power  set.  However,  this  scheme  is  not 
practical  as  the  speed  of  the  main  motor  is  usually  very 
slow.  Hence  a  large  slow-speed  commutator  motor 
would  be  required,  which  would  be  special  for  prac- 
tically every  s{>eed  and  rating,  while  when  driving  the 
induction  generator  the  speed  can  be  made  high  and 
can  be  standardized  for  a  rating  independent  of  motor 
speed. 

The  Frequency  Converter  System  is  a  scheme  in 
which  the  low  frequency  of  the  rotor  circuit  is  con- 
verted to  another  higher  frequency,  which  is  used  in 
auxiliarj'  alternating-current  apparatus  for  constant 
horse-power  sets  or  returned  directly  to  the  line 
through  transformers  in  constant  torque  sets.  Thi.^ 
-ystem  is  explained  more  in  detail  than  the  others  as 
It  is  new  to  most  people  and  includes  some  rela- 
tions which  occur  in  all  adjustable-speed  induction- 
motor  sets. 

In  the  constant  torque  outfit,  the  frequency  con- 
verter is  mounted  on  the  same  shaft  as  the  main  motor 
and  usually  has  the  same  number  of  poles.  This  fre- 
quency changer  is  similar  to  a  rotary  converter,  hav- 
ing an  armature  with  collector  rings  on  one  end  and 
r.  commutator  on  the  other.  The  stator  does  not  have 
any  winding  but  consists  merely  of  a  magnetic  keeper 
to  decrease  the  magnetizing  current.  The  brushes  on 
the  commutator  are  spaced  so  as  to  collect  polyphase 
currents,  i.e.,  three  brush  arms  per  pole  pair  for  three 
phase  and  six  per  pole  pair  for  six  phase.     The  cul 


September,  192 1 


THE   ELECTRIC   JOURNAL 


387 


lector  rings  are  connected  to  a  source  of  variable 
voltage  obtained  from  the  same  line  which  supplies 
the  primary  of  the  main  motor. 

If  this  set  is  rotating  at  synchronous  speed,  the 
frequency  changer  acts  like  a  direct  current  rotary 
converter  and  direct  current  is  generated  on  the  com- 
mutator side  when  line  frequency  is  on  the  collector 
rings.  In  order  to  explain  this  action,  the  converter 
can   be   considered   as   two   separate   machines,   an   in- 


FU:    4 — MAIN    MOTOR   OF    FKEQl'ENCY   CONVERTER    SYSTEM 

At  the  Scullen  Steel  Coinpany,  St.  Louis,  Mo. 

duction  motor  and  a  direct  current  generator.  The 
line  frequency  is  supplied  to  the  rotor  so  that  the  tield 
rotates  around  the  rotor  periphery  at  synchronous 
speed  and,  since  the  rotor  itself  is  rotating  in  the  op- 
posite direction  at  the  same  speed,  the  field  itself  is 
standing  still  in  space.  These  stationary  fields  corre- 
spond to  the  field  poles  of  the  direct  current  machine 
so  that  the  voltage  at  the  brushes  on  the  commutator 
is  direct  current.  The  voltage  which  appears  on  the 
commutator  bears  a  definite  relation  to  the  voltage  on 
the  collector  rings,  the  same  as  on  a  standard  rotary 
converter,  i.  e.,  the  voltage  will  be  proportional  to  the 
voltage  supplied  to  the  collector  rings  and  will  not  be 
changed  by  rotating  the  armature  at  different  speeds. 

At  two-thirds  speed,  the  field  in  the  frequency 
changer  will  not  be  stationary,  but  will  rotate  back- 
wards at  one-third  speed  since  the  field  is  rotating 
backwards  at  normal  speed  with  respect  to  the  rotor 
and  the  rotor  is  rotating  forward  at  only  two-thirds 
the  normal  speed.  Since  the  brushes  are  stationary, 
the  frequency  which  appears  at  them  will  depend  on 
the  speed  of  the  field  in  space,  in  this  case  one-third 
of  line  frequency. 

At  four-thirds  speed,  the  rotor  is  rotating  for- 
ward faster  than  the  field  on  the  rotor  periphery  is 
rotating  backwards,  so  that  the  speed  of  the  field  in 
space  is  one-third  of  normal  speed  forward.  If  the 
frequency  below  synchronism  is  considered  positive 
and  that  above  negative,  it  is  seen  from  the  above  rea- 
sonmg  that  the  frequency  of  rotation  plus  the  fre- 
quency on  the  commutator  in  Fig.  6  is  equal  to  the 
frequency  on  the  collector  rings.  This  applies  whether 
the  frequency  on  the  collector  or  the  frequency  of  ro- 
tation is  kept  constant.  By  frequency  of  rotation  is 
meant  that  frequency  which  corresponds  to  the  speed 
and  number  of  poles.  In  these  sets,  the  frequencies  in 
the  different  machines  must  always  be  correct  or  the 
machines  will  hunt  and  pull  out  of  step,  dravving  large 


currents  from  the  line. 

The  relation  of  fre((uencies  can  be  shown  to  be 
correct  for  the  constant  torque  set  as  follows.  The 
frequency  at  b  is  the  slip  frequency  sf,  the  speed  being 
(/ — s)f.  As  shown  before,  the  frecjuency  on  c  plus 
the  frequency  c  equals  the  frec^uency  d,  or  in  other 
words,  sf  -\-  {1 — s)f  :^  the  frequency  on  d  which  is  / 
so  that  the  frequency  of  d,  considered  through  the  main 
motor,  is  equal  to  lliat  of  the  line  and  can  be  con- 
nected to  it. 

In  order  to  change  the  s[)eed  in  this  set,  means  are 
provided  between  d  and  the  line  to  vary  the  impressed 
voltage  applied  to  the  collector  rings.  When  the  volt- 
age on  the  collector  rings  d  is  changed,  the  speed  ad- 
justs itself  until  the  current  is  just  sufficient  to  carry 
the  load.  As  an  example,  assume  that  the  speed  is  to 
he  increased  when  the  main  motor  is  running  below 
synchronism  at  constant  torque.  The  load  current  in 
the  rotor  is  produced  by  the  difference  between  the 
voltage  produced  by  the  rotor  of  the  main  motor  and  a 
smaller  voltage  from  the  commutator  of  the  frequency 
changer.  Now  to  increase  the  speed  below  synchron- 
ism, the  voltage  on  the  commutator  is  decreased.  This 
allows  the  larger  difference  between  the  main  motor 
voltage  and  the  commutator  voltage  to  send  more  ctu"- 
rent  through  the  rotor,  thus  increasing  its  torque  and 
accelerating  the  rotor.  As  the  rotor  accelerates,  the 
voltage  from  the  rotor  decreases  until  the  difference  be- 
tween the  two  voltages  is  the  same  as  before  and  the 
normal  current  is  flowing  in  the  rotor  circuit. 

A  numerical  example  of  the  action  may  be  clearer. 
Assuming  a  set  operating  at  a  normal  speed  of  three 
p.ercent  below  synchronism  and  recjuiring  a  secondary 


5— Fl;EijrKN(  V     (  O.WKKTEi; 

.Scullen  Steel  Co.,   St.   Louis,   Mo. 


voltage    of    30    volts    to    send    the    necessary    current 
through  the  rotor  circuit. 

Next,  a  voltage  of  70  volts  is  applied  to  the  col- 
lector rings,  which  opposes  the  30  volts  generated  in 
the  rotor  of  the  induction  motor,  and  causes  a  decrease 
in  the  rotor  current  and  torque  so  that  the  rotor  slows 
down.  In  slowing  down,  the  rotor  x'oltage  increases 
and,  in  order  to  produce  enough  current  in  the  rotor 


388 


THE    ELECTRIC   JOURNAL 


Vol.  X\iri,  No.  9 


circuit  to  carr)-  the  load,  the  generated  rotor  volts  must 
exceed  the  counter  voltage  from  the  frequency  changer 
by  30  volts  or  it  must  be  equal  to  100  volts.  The  gen- 
erated secondary  voltage  is  proportional  to  the  slip  and 
since  30  volts  corresponded  to  three  percent  sli]),  100 
volts  gives  ten  peixent  slip. 

If  the  voltage  of  70  volts  is  reversed  so  as  to  help 
the  30  volts  generated  in  the  rotor  of  the  inducticjn 
motor,  the  current  which  would  flow  in  the  rotor  cir- 
cuit would  be  much  larger  than  that  required  to  carry 
the  load  and  the  motor  speed  would  increase.  .Vs  the 
motor  approaches  synchronous  speed  the  generated 
voltage  will  decrease  to  zero  and  above  synchronous 
speed  the  voltage  will  increase  again  but  in  the  opposite 
sense,  so  that  it  would  subtract  from  the  70  volts  su[)- 
plied  by  the  frequency  changer,  increasing  as  the  s])eed 
increased,  until  only  30  volts  were  left  to  produce  the 
necessary  current  for  the  load.  This  would  be  when 
ihe  generated  volts  were  40  volts  or  when  the  motor 
was  running  at  four  percent  above  synchronism.  From 
this  it  is  seen  that  with  the  same  voltage  values  on  the 
frequency  changer,  the  speed  change  is  an  equal 
amount  above  and  below  the  normal  speed  of  the  in- 
duction motor  and  not  above  and  below  the  synchron- 
ous speed. 


Two-Thirds  Spttd 


601/ 


Synchronous  Speed 
600^ 

/ 


Four  Thirds  Speed 
-iOO; 


KU;.  6 — KkEoUK.M-V   .\T  COMMl'LVTOR  OK  FKEyUEXtV   Cll  .\.Nl',!;k    AT 
V.\K10US     SPEEDS 

The  usual  set  is  slow  speed  and  the  frequency 
converter  becomes  extremely  large  when  made  with  the 
same  number  of  poles  as  the  main  motor,  so  that  this 
system  works  out  best  as  a.-^onstant  horse-power  set, 
in  which  a  synchronous  motor  is  mounted  on  the  main 
motor  shaft  and  the  frequency  converter  is  driven  at 
some  higher  speed  by  a  synchronous  motor,  as  shtjwn 
in  Fig.  8.  The  auxiliary  synchronous  motor  has  the 
same  number  of  poles  as  the  main  motor  and  the  driv- 
ing motor  for  the  frequency  converter  has  the  same 
number  of  poles  as  the  frequency  converter.  In  this 
case  the  frequency  generated  in  the  auxiliary  machine 
is  proportional  to  the  speed,  or  is  one  minus  the  slip 
(/ — s),  being  less  than  the  line  frequency  below  syn- 
chronism and  greater  when  operating  above. 

The  relationship  of  the  frequencies  in  this  set  can 
be  shown  as  follows.  In  this  case  the  phase  rotation 
between  the  rotor  of  the  main  motor  and  the  commu- 
tator is  reversed  with  respect  to  the  other  set,  so  that 
the  slip  frequency  has  a  negative  sign. 

The  line  frecjuency  /  is  supplied  to  the  stator  a  so 
that  the  slip  frequency  at  b  is  sf  and  the  speed  is 
(/ — s)f  as  before.  In  this  case,  the  frequency  changer 
is  driven  by  a  synchronous  motor  or  the  speed  of  ro- 
tation is  /.  As  before,  the  commutating  frequency 
plus  the  rotational  frequency  equals  the  collector  fre- 


quency and,  keeping  in  mind  the  reversal  of  lead  be- 
tween b  and  r,  c  +  /  =  rf  or  —  {sf)  -\-  f  =  ( / — s)f 
which  agrees  with  the  frequency  generated  by  the  aux- 
iliary alternating  current  generator  g  which  has  the 
same  number  of  poles  as  the  main  motor  and  runs  at 
the  same  speed,  i.  e.,  (  / — s)j. 

The  s[)eed  in  tiiis  set  is  changed  b)-  changing  the 
excitation  on  the  auxiliary  generator  </.  For  the  low- 
est speed,  the  field  is  at  its  maximum  in  one  direction, 
and  to  increase  the  speed  the  field  is  weakened  until 


I 


^: 


Frequency  Converter 

FIG.    7 — SlllKM.MIC    D1A(;H.\M    OF    CONST.\NT    TOKnLT.    FREorE.NCV 
CONVERTER    SYSTEM 

at  no  field  the  set  is  operating  slightly  below  synchron- 
ous speed.  To  increase  the  speed,  the  field  is  re- 
versed and  again  increased  to  the  maximum  value. 
Since  the  field  copper  is  usually  the  limit  on  synchron- 
(His  machines,  the  same  field  above  and  below  .syn- 
chronism will  generate  a  larger  voltage  abo\e  syn- 
chronism due  to  the  increased  speed,  than  is  generated 
below  and  this  difference  more  than  offsets  the  de- 
crease in  range  above  synchronism  due  to  the  normal 
slip  when  no  field  is  on,  and  gives  a  larger  range  above 
than  below. 

These  sets  also  allow  of  easy  ]ihase  correction  by 
changing  the  position  of  the  brushes  on  the  fretpiency 
converter.  If  the  voltage  from  the  commutator  of  the 
frequency  changer  is  in  direct  opposition  in  time  to  the 
rotor  voltage,  there  will  be  no  change  in  power-factor 
conditions,  but  if  the  brushes  are  shifted  one  way  or 
the  other,  the  voltage  impressed  on  the  rotor  is  not  in 
line  with  the  rotor  voltage  and  can  be  considered  as 
two  voltages  at  right  angles  to  each  other,  one  in  line 
with   the   rotor  voltage  and   the   other  at    right   angles 


K,,-,.    8— SCHEM.\TU-    DIAGRAM    OF   CONSTANT    HORSE-POWER    IKE- 
gCENCY    CONVERTER    SYSTEM 

to  the  rotor  voltage.  The  component  in  line  with  the 
rotor  voltage  will  cause  a  change  in  speed,  but  the  volt- 
age at  right  angles  will  cause  a  current  to  flow  at  right 
angles  to  the  load  current  which  will  either  assist  the 
magnetizing  current  of  the  stator  in  magnetizing  the 
motor  and  so  increase  the  power-factor  of  the  current 
taken  from  the  line,  or  it  may  oppose  the  main  motor 
magnetizing  current  and  cause  the  main  motor  to  draw 
more  magnetizing  current  from  the  line  and  so  de- 
crease the  power-factor  of  the  main  motor.     Movmg 


September,   1921 


THE    ELECTRIC    JOURX.IL 


389 


the  brushes  one  way  will  raise  the  power-factor  while 
a  movement  in  the  opposite  direction  will  decrease  the 
IKiwer-factor. 

The   magnetizing    current    taken    by    the    motor    is 
constant,  so  that  a  constant  voltage  at  right  angles  to 


range.  Therefore,  means  are  provided  for  changing 
the  brush  position  for  different  speeds  to  obtain  ap- 
jiroximately  constant  power-factor. 

This    can    be    done    either    by    actually    shifting 
brushes  or  by  shifting  the  center  line  of  the  poles  on 


the  working  current  will  be  required  to  give  the  same  the  driving  motor  which  is  the  easiest  practical  way. 

power-factor  at  a  certain  torque.     Since  the  voltage  on  The  driving  motor   is   wound  with  a  distributed  field 

the  rotor  near  synchronism  is  small  compared  to  that  and  the  center  line  of  the  field  is  shifted  by  varying 

\\lien  near  the  hmits  of  the  speed  range,  a  larger  shift  the  excitation  on  the  different  parts  of  the  windings  by 

will  be  necessary  near  synchronism  to  give  the  same  means  of  a  field  rheostat  which  is  governed  by  a  relay 

voltage  than  is  necessary  near  the  limits  of  the  speed  in  the  primary  circuit. 


S#)5ta4l0ji^  ^OT  Unvnrsmj^;  iVffll  iV(oi;or^ 


\\'( 


G.  P.  UlLSON 

Switchboard  Engineer, 
stin.uhouse  Electric  &   Mfg.  Company 


DL'E  to  the  importance  of  keeping  steel  mills  in 
continuous  operation,  careful  consideration 
should  be  given  to  every  detail  in  their  design. 
The  amount  and  nature  of  the  electrical  equipment  re- 
quired for  the  operation  of  a  mill  is  extensi\e  and 
varied*.  In  man\-  cases,  it  is  difficult  to  house  this 
macliiner\-  properly  and  locate  it  efficiently.  It  is 
located  out  in  the  mill,  subject  to  dirt  and  dust  from 
which  it  must  be  protected.  This  location  is  deter- 
mined by  the  i)osition  of  the  rolls.  In  deciding  the 
laxout  of  the  mill,  the  substation  location  is  usually- 
given  secondary  consideration.  In  many  cases,  the 
equipment  is  to  replace  a  steam  engine  drive  and  must 
be  located  approximately  in  the  space  occupied  by  the 
engine.  Thus,  to  a  great  extent,  the  physical  design 
of  the  building  is  limited. 

Properly  speaking,  the  designing  of  the  substation 
means  assembling  the  equipment  and  building  in  the 
proper  location  around  the  re\ersing  mill  motor.  It 
is  obvious  that  to  get  the  desired  results  under  the 
abo\e  conditions,  careful  consideration  must  be  gi\en 
to  those  important  features  that  go  to  make  a  well 
ciesigned  substation.  These  features  are  space,  ac- 
cessibilit\',  visibilitv,  s\-mmetrv  and  economy. 


A  "cramped"  substation  is  poorly  designed.  \et 
this  is  one  of  the  most  common  faults.  Engineers 
often  seem  to  forget  that  machinery  ma\-  need  to  be 
repaired  and  lose  sight  of  the  importance  of  space  for 
depositing  parts  of  the  machinery  when  it  is  necessary 
to  make  these  repairs.  Too  much  importance  cannot 
be  placed  on  this  feature.  Loss  of  i>roduction  in  a 
steel  mill  is  of  far  greater  importance  than  economy 
of  space.  If  a  mill  is  shut  down  for  repairs,  such  re- 
pairs must  be  made  quickly,  and  ample  space  must  be 
available  for  the  disposition  of  removed  [larts  and 
parts  required  to  make  the  repairs.  The  station, 
therefore,   should,  have  adequate   room   to_  deposit   the 


*See   an   article  on  "Motor   Driven   Plate   Alills"  by   F. 
Egan,  in  this  issue. 


D. 


upper  half  of  the  motor  frame  and  any  other  removed 
parts  while  the  armature  is  being  changed. 

.ACCESSIBILITY 

The  equipment  should  be  readily  accessible  with 
the  crane  hook  or  other  means  for  its  removal.  Time 
lost  in  this  operation  further  impairs  production.  It 
should  also  be  easily  accessible  to  the  station  attendant. 
Especially  is  this  true  of  the  tie  panel,  slip  regulator, 
switching  and  control  equipment.  The  bed  plates  for 
the  motor  and  flywheel  motor-generator  set  should  be 
set  in  the  floor  t(j  a  depth  permitting  only  about  1.5 
m.  projection  above  the  floor  line.  This  will  greatly 
increase  the  accessibility  of  the  bearings  for  inspection. 
Ouite  frequently  the  floor  line  of  the  mill  is  at  a  lower 
elevation  than  can  readily  be  obtained  in  the  motor 
room.  To  bring  the  motor  to  the  mill  elevation  re- 
([uires  that  it  be  set  in  a  ])it.  This  pit  should  be  of 
sufficient  dimensions  to  permit  access  to  the  motor  on 
.•dl  sides.  If  the  pit  and  motor  foundation  are  made 
at  the  same  time  and  completed  before  the  motor  bed 
plate  is  put  in  ]>lace,  a  space  of  at  least  one  foot  must 
he  [M-ovided  all  around  between  the  motor  foundation 
and  the  ])it  floor  for  lowering  and  adjusting  the  bed 
plate  onto  the  foundation  as  shown  in  Fig.  I.  This 
space  will  be  sufficient  for  the  removal  of  the  crane 
hook  and  any  necessary  adjustment  of  the  motor  bed 
plate.  After  the  plate  has  been  properly  placed  and 
rigidly  bolted,  the  sjtace  can  be  filled  in  to  the  level  of 
the  pit  floor.  The  best  arrangement,  of  course,  is  not 
to  put  in  the  pit  floor  until  the  bed  plate  is  on  the  foun- 
dation. 

VISIBILITY 

All  of  the  equipment,  especially  the  slip  regulator 
and  switching  e(|uipment,  should  be  visible  to  the  sta- 
tion attendant.  It  is  very  impoi'tant  that  he  be  able  to 
see  from  his  position  at  the  switchboard  the  movement 
and  position  of  the  regulator  arm  at  the  time  of  the 
starting  of  the  flywheel  set.  Therefore,  the  slip 
regulator  should  be  set  out  in  the  room  so  as  not  to  be 
obscured  by  any  other  piece  of  machinery. 


390 


THE    ELECTRIC    JOURNAL 


Vol.  XVIII,  No.  9 


SYMMETRY 

A  well-balanced  and  symmetrical  substation  is 
much  to  be  desired.  No  one  likes  a  station  that  has  no 
symmetry  regarding  location  of  apparatus,  but  looks  as 
if  the  equipment  had  been  installed  where  it  happened 
to  be  placed  when  received.  The  essential  features 
should  not,  however,  be  sacrificed  for  symmetry. 
Usually,  if  consideration  is  given  this  feature  of  de- 
sign   before    -the    building    dimensions    are    definitely 


MOTOR    KOU.NDATIONS 

Showing  method  of  leaving  space  for  bed  plate  adjustment. 
This   space   to   be   filled   in   after   the   bed   plate   is   set   on   the 

foundation. 

settled,  fairly  good  results  can  be  obtained.  But  in 
stations  where  this  feature  has  not  been  considered  in 
determining  the  substation  dimensions,  one  is  indeed 
fortunate  if  he  can  combine  the  essential  features  and 
yet  obtain  the  desired  features  of  symmetry.  Fig.  2 
shows  the  floor  plan  of  a  reversing  mill  motor  sub- 
Station  that  combines  the  above  features 
to  a  very  reasonable  degree,  with  the  ex- 
ception of  the  air  washer.  The  location 
shown  for  it  was  necessary  on  account 
of  other  machinery  being  located  beyond 
the  blower  motor,  thus  preventing  the 
reversing  of  the  washer  equipment. 
Space  is  available  between  the  direct- 
current  control  board  and  air  washer 
for  depositing  the  removed  parts  when 
necessary  to  make  repairs  on  the  revers- 
ing mill  motor.  The  available  space  is 
however,  more  or  less  cramped,  making 
it  awkward  to  dodge  the  control  board. 
It  is  obvious  that  the  design  of  the  sta- 
tion would  have  been  much  improved,  If 
the  air  washer  could  have  been  re- 
versed. 


waste,  especially  where  no  real  value  is  obtained  by  the 
additional  expense.  Most  stations  are  free  of  this 
fault.  More  often  it  is  the  case  of  carrying  economy 
too  far  and  eliminating  some  feature  that  would  add 
to  the  reliability  and  efficiency  of  the  station.  The  im- 
portant feature  that  seems  to  fall  most  often  under  the 
economic  necessity  for  elimination  is  the  basement.  In 
most  stations,  the  elimination  of  a  basement  is  poor 
economy  and  a  detriment  to  properly  designing  the 
station.  Some  of  the  apparatus  required  for  a  revers- 
ing mill  could  more  conveniently  be  located  in  the  base- 
ment than  any  other  place  in  the  station.  Especially 
is  this  true  of  the  blower  and  air  washer.  This  equip- 
ment can  be  installed  in  the  basement  at  a  lower  cost 
and  will  operate  more  efficiently  than  on  the  main  floor. 
I'igs.  3  and  4  show  a  photograph  and  section  of  n 
double  unit  reversing  mill  motor  substation  with  a 
basement  and  the  air  washer  and  blower  installed 
therein. 

SECONDARY   DESIGN'    FEATURES 

There  are  certain  secondary  features  that  assist 
materially  in  making  a  well  designed  station.  These 
may  he  designated  as  the  location  of  the  equipment 
with  respect  to  the  apparatus  to  which  it  is  closely 
associated,  and  the  method  of  installing  the  connections 
between  the  ecjuipmcnt. 

AIK   WASHER 

The  location  and  installation  of  the  air  washer 
and  blower  is  a  special  problem  in  itself.     The  size  of 


ECONOMY 


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Reversing 
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Running  connecting  rods  for  hand  JJ^-a  toPuiWp"™' 
operated  circuit  breakers  in  trenches  is  n ;.  i-FLooR  plan  for  single  unit  reversing  mill  motor  slestation 
unsatisfactory.  The  trench  is  a  catch  all  for  dirt  and  the  equipment  is  determined  by  the  volume  of  air  re- 
interferes  with  keeping  the  floor  clean.  It  quired  by  the  motor  to  keep  the  windings  at  the  proper 
adds  to  the  expense  of  laying  the  floor  and  requires  temperature.  Its  location  must  be  at  some  point  where 
the  purchasing  of  iron  covering  for  the  trenches,  outside  air  can  be  taken  into  the  washer.  This  pomt 
Economy  may  not  be  considered  an  important  must  be  relatively  close  to  the  motor,  as  a  long  air  duct 
feature  in  the  design  of  such  a  station,  but  pre-  decreases  the  velocity  of  the  air  and,  therefore,  the 
cautions    should    be    taken    to    eliminate    unnecessary  volume  entering  the  motor.     The  duct  should  also  be 


September,  1921 


THE    ELECTRIC   JOURNAL 


391 


as  straight  as  possible.  Bends  and  turns  reduce  the 
velocity  of  the  air  rapidly,  especially  if  they  are  short 
turns.  For  this  reason,  when  it  is  impossible  to  elimin- 
ate bends  in  the  air  duct,  these  turns  should  be  made 
with  long  radii  to  reduce  the  friction  loss  to  a  mini- 
mum. 

DESIGN   AND   CONSTRUCTION   OF  AIR  DUCT 

The  air  duct  may  be  made  either  of  sheet  steel  or 
concrete.  If  of  concrete,  care  must  be  exercised  in 
finishing  the  walls.  The  velocity  of  the  air  is  so  great 
that  it  cuts  the  walls  and  carries  particles  of  concrete 
and  sand  into  the  motor  winding  unless  the  walls  are 
smooth.  In  addition,  the  walls  should  be  painted  once 
or  twice  a  year  with  a  hard  finish  asphalt  paint.  An 
entrance,  should  be  provided  for  workmen  to  enter  the 
duct  to  do  painting  or  any  necessary  repairs.  In  a 
station  without  a  basement  it  is  much  simpler  and  more 
permanent  to  make  the  duct  of 
concrete  than  to  arrange  for  the 
protection  from  rust  of  a  metal 
duct  buried  in  the  earth  under- 
neath the  station  floor.  With  a 
metal  duct  the  best  construction 
would  still  be  a  concrete  duct,  steel 
lined. 

Outside  Entrance  to  Duct — 
Precaution  must  be  taken  to  pro- 
tect the  outside  air  entrance  to  the 
air  washer  from  snow  and  icy  air. 
The  entrance  should  be  provided 
with  a  door  that  closes  the  outside 
entrance  and  opens  an  entrance 
from  the  motor  room,  as  shown  in 
Fig.  4.  Two  separate  doors 
should  never  be  provided  for  these 
entrances  unless  they  interlock  sn 
that  the  attendant  cannot  close  one 
without  opening  the  other.  In 
continuously  warm  climates  the 
double  door  feature  is  unneces- 
.sary,  the  outside  entrance  being  sutificient. 

FLY-WHEEL  SET 

The  location  of  the  fly-wheel  motor-generatur  .>et 
should  be  selected  with  a  view  of  giving  the  station 
a  balanced  appearance  and  of  reducing  the  length  of 
the  tie  circuit  connection  between  the  generator  and 
the  motor.  As  the  location  of  the  mill  motor  depends 
entirely  upon  the  position  of  the  mill,  the  flywheel  set, 
which  has  somewhat  the  same  physical  dimension  as 
the  motor,  should  be  located  to  off-set  the  motor,  giv- 
ing a  symmetrical  and  balanced  appearance  to  the  sta- 
tion. The  location,  of  course,  is  flexible,  depending 
upon  the  physical  design  of  the  station,  but,  in  general, 
It  should  be  as  near  as  possible  to  the  motor,  as  the 
tie  circuit  between  the  generator  and  the  motor  is 
usually  expensive  to  install  and  considerable  amount 
of  copper  is  required  to  carry  the  heavy  current.     This 


llexibilit)'  in  locating  the  flywheel  motor-generator  set 
is  shown  clearly  by  Figs.  J  and  3. 

TIF.    CIRCUIT    BREAKER    PANEL   AND   EXCITER   SET 

In  locating  the  flywheel  set  and  the  tie  connection 
between  the  generator  and  the  motor,  the  tie  circuit 
i)reaker  panel  and  the  exciter  set  must  be  considered. 
Both  of  these  are  connected  in  the  tie  circuit.  There- 
fore, provision  should  be  made  for  properly  locating 
each  of  these  somewhere  along  this  connection. 
ITsually  they  are  located  near  each  other.  There  is  no 
essential  reason  for  this  location  except  that  having 
these  two  located  together  usually  adds  to  the  balanced 
appearance  of  the  station.  The  connections  from  the 
lie  circuit  into  these  two  pieces  of  apparatus  are  made 
with  copper  strap.  These  connections  are  uninsulated 
;tnd,  if  left  exposed,  afford  more  or  less  danger  from 
accidental    contact.     The   appearance   and    safetv    fea- 


3 — STATION    LAYOUT    ul 


iH    i:ase.\ient    and 


BALuONy     KOK    SW1TCHB0.'\RD 

ture  will  be  considerably  improved  by  enclosing  the 
rear  of  the  tie  panel  in  grill  work*,  having  a  door  for 
accessibility  in  the  rear,  and  enclosing  the  connections 
to  the  exciter  in  wood  moulding.  Fig.  5  shows  an  ex- 
citer connection  enclosed  in  wood  moulding.  It  con- 
sists of  a  board  one-half  to  one  inch  thick  having 
three  wooden  strips,  nailed  on  it,  one  on  each  out- 
side edge  and  one  in  the  middle,  forming  two 
grooves,  with  the  width  of  each  groove  the  same  as 
the  copper  strap  making  the  connection.  The  two 
strips  on  the  outside  edges  should  be  at  least  one-half 
inch  wide.  The  thickness  should  be  equal  to  or 
slightly  more  than  the  thickness  of  the  copper  connec- 
tions. The  width  of  the  middle  strap  should  be  the 
same    as    the    distance    between    the    two    connections. 


*As  shown  in   Fig.   12  of  ]Mr.   Egan's  article' in  this 


392 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


The  cover  should  consist  of  a  board  having  the  same 
dimensions  as  the  base.  Small  wood  screws  can  be 
used  to  hold  it  in  place.  Any  color  or  finish  can  be 
applied  to  the  moulding.  A  glossy  black  paint  to  re- 
semble the  finish  of  the  exciter  set  makes  a  very  satis- 
factory installation. 

SLIP    REGULATOR 

The  slii)  regulator,  should  be  located  so  as  to  be 
visible  to  the  station  operator  from  his  position  at  the 

O        •  I 


VK,.    4 — SlXTIci.N'    l)K    A    KEVF.RSINC    MII.I.    Srii.ST.ATlON 

Showing  location  and  construction  of  air  washer,  blower 
and  air  duct,  foundation  of  mill  motor  and  method  of  mak- 
ing connections. 

switchboard.  The  distance  between  the  regulator  and 
the  motor  and  the  distance  to  the  station  drainage  .sys- 
tem should  be  taken  into  consideration.  The  connect- 
ing leads  between  the  regulator  and  the  secondary  of 
the  motor  are  comparatively  heavy,  and  therefore,  to 
eliininate  unnecessary  expense,  the  distance  between 
the  regulator  and  the  motor  should  be  reduced  to  a 
minimum.  The  regulator  in  all  cases  .should  be  pro- 
\ided  with  a  pit  of  sufificient  dimensions  to  hold  the 
entire  capacity  of  electrolyte.  This  pit  should  be  ]uo- 
vided  with  an  outlet  connecting  to  the  drainage  sys- 
tem. This  feature  will  in  many  cases  influence  the 
selection  for  properly  locating  the  regulator. 

PRIMARY    PANELS   AND    SWITCHING    EQUIPMENT 

The  proper  location  of  this  equipment  is  deter- 
r.iinad  to  a  very  great  extent  by  the  point  of  entrance 
of  the  incoming  line.  The  switching  equipment  .should 
be  located  as  near  this  point  as  practical,  thereby 
eliininating  any  long  run  of  incoming  leads.  If  the 
oil  switches  are  manually  operated,  the  switchboard 
panel,  having  mounted  thereon  the  oil  circuit  breaker 
handles  and  cover  plates,  should  be  placed  in  front  and 
near  the  structure  supporting  the  switching  equipment. 
This  location  will  eliminate  any  long  run  of  connecting 
rods  and  instrument  cables,  and  will  reduce  the  cost 
of  providing  trenches  for  the  circuit  breaker  connect- 
ing rods.  If  the  circuit  breakers  are  electrically  oper- 
ated, the  above  conditions  affecting  the  location  of  the 
panels  need  not  be  considered,  except  to  the  extent  of 
reducing  to  a  minimum  the  length  of  instrument  and 
control  cables  and  their  respective  conduits.  The  elec- 
trically-operated equipment  thus  permits  greater  flexi- 
bility of  arranging  and  locating  the  panels.  As  pointed 
out,  these  panels  .should  be  located  so  that  the  whole 
station  equipment  is  more  or  less  directly  under  the 
operator's  vision  from  any  point  at  the  switchboard. 
This    condition    can    be    obtained    more    readilv    and 


usually  with  less  cost  and  trouble  with  an  electrically- 
operated  switching  equipment,  than  with  a  manually- 
operated  installation.  Fig.  6  shows  a  section  of  a  pipe 
frame  structure  supporting  manually-operated  switches 
and  equipment  located  directly  in  the  rear  of  the 
panels.  Fig.  7  .shows  a  section  of  an  electrically-oper- 
ated circuit  breaker  cell  structure  also  located  directly 
in  the  rear  of  the  panels. 

In  stations  requiring  extensive  switching  equip- 
ment, such  as  additional  equipment  for  incoming  lines, 
feeders  for  rotary  converters,  motor-generator  sets, 
and  lightning  protective  equipment  for  the  incoming 
lines,  the  above  arrangement  will  usually  be  found  dififi- 
eult  to  carry. out.  A  crowded  condition  usually  re- 
sults in  any  attem|)t  to  locate  the  equipment  all  on  the 
same  floor.  If  the  substation  has  a  basement  and  the 
eeiuipment  is  as  extensive  as  indicated  above,  the  oil 
switches  can  be  located  to  very  good  advantage  in 
this  basement  and  the  switchboard  jianel  immediately 
above  on  the  main  floor.  The  lightning  arrester  equip- 
ment should  be  mounted  near  the  incoming  line.  If 
inside  the  building,  its  location  ma\'  be  either  on  the 
main  floor  in  the  rear  of  the  board,  or  on  a  small 
balcony  abo\e.  1  f  outside  the  building,  it  may  be 
placed  advantageously  on  the  roof  of  the  substation, 
es])ecially  if  outdoor  space  is  at  a  premium.  Various 
other  arrangements  of  the  equipment  may  be  carried 
out  depending  upon  the  conditions  in  each  individual 
case. 

EIKLD  CONTROL  EQUIPMENT 

The  location  of  the  field  control  equipment  is  not 
intluenced  by  its  electrical  relation  to  any  other  equip- 
ment, except  in  a   small  degree  to  the  mill   operator's 


fk;.  5_exciter  connections 
Snowing  method  of  enclosing  leads  in  wood  moldnig. 

pulpit.  This  relation,  however,  is  only  relative  and  is 
due  to  the  number  of  wires  between  it  and  the  master 
control  switch  and  pulpit  panels.  It  is  interconnected 
with  most  of  the  equipment  in  the  station.  The  wires, 
however,  are  small  and  relatively  few,  except  in  the 
case  of  the  master  control  switch  and  pulpit  panel.  lu 
order  to  reduce  the  length  of  these  leads  and  their  con- 
duits it  may  be  advisable  to  locate  it  in  the  station  near 
the  operator's  pulpit.     The  mill  motor  is  always  located 


September,   iqji 


THE    ELECTRIC    JOURNAL 


393 


at  this  side  of  the  building  and  as  its  fields  are  con- 
nected to  the  control  panel  by  a  number  of  wires,  this 
location  will  in  most  cases  be  found  to  be  the  most  sat- 
isfactory. This  location  should  not,  however,  be  ad- 
hered to,  to  the  detriment  of  other  important  features 
of  design,  such  as  symmetry  and  space.  The  amount 
saved  in  cable  and  conduit  w  ill  usually  not  be  sufficient 
to  warrant  this  sacrifice. 

This  control  board  is  usually  of  the  same  height 
and  general  appearance  as  the  primary  panels.  There- 
fore, if  it  can  be  erected  near  and  in  line  with  the 
primary  panel,  it  will  add  in  most  cases  to  the  general 
appearance  of  the  station.  This  station  shown  in  Fig. 
2  has  such  a  location  of  the  control  board  . 


.jyu 


KK,.     6 — SECTION     OF    SWITCHIiOAKIl 

With  a  pipe  structure  supporting  the  circuit  breaker  equip- 
ment mounted  in  the  rear. 

GRID  RESISTORS  FOR  MOTOR  AND  GENERATOR  FIELDS 

The  grid  resistances  are  connected  to  the  various 
contactors  of  the  control  board.  The  operation  of 
these  switches  cuts  in  and  out  the  various  grids  as 
desired.  Therefore,  to  reduce  troubles  and  cost  of  in- 
stalling, these  resistance  grids  should  be  mounted  as 
near  this  board  as  possible.  If  mounted  (jn  the  floor 
back  of  the  board,  considerable  space  and  extra  wiring 
IS  required.  To  mount  them  in  the  basement  under- 
neath the  board  some  attention  to  ventilation  ma>-  be 
required.     The  most  satisfactory  location  is  to  arrange 


them  at  the  top  and  in  the  rear  of  the  panels,  as  shown 
u\  I'ig.  S. 

SWITCHING  EQUIPilENT 

The  correct  installation  of  the  switching  equip- 
ment is  of  such  importance  to  its  successful  operation 
that  careful  consideration  should  be  given  to  its  erec- 
tion. The  most  important  feature  in  the  erection  of 
this  equipment  is  the  mounting.  If  the  circuit  breakers 
are  mounted  on  a  masonry  wall,  the  supporting  bolts 
should  be  either  well  embedded  or,  if  the  walls  are 
thin,  run  through  the  wall  and  a  plate  added  under  the 
bolthead.  If  supported  on  pqie  framework,  they 
should  be  placed  so  that  no  excessive  strain  is  e.xerted 
upon  any  section  of  the  pipe.  The  pipe  structure 
should  be  well  braced,  rigid  and  able  to  withstand  the 
strain  of  opening  and  closing  the  circuit  breakers  with- 


nc.    7 — SECTION    OF    SWITCHIIO^KD    IN    SI\T10\    WITHOtiT    Ii.\SEMENT 

Showing  electrically-operated  circuit  breaker  cell  structure 
mounted  in  the  rear  of  the  panel  board,  lu  a  station  having 
a  basement  it  would  be  desirable  to  mount  this  circuit  breaker 
structure  in  the  basement  and  mount  the  switchboard  on  the 
main  floor  above  and  in  front  of  the  lightning  arrester  eciuil)- 
inent.  Another  alternative  to  either  of  the  above  schemes,  which 
is  frequently  desirable,  is  to  mount  the  lightning  arrester  equip- 
ment on  the  substation  roof  or  in  a  gallery  above  the  floor. 

out  excessive  \il)ration.  The  large  circuit  breakers 
should  be  supported  both  in  front  and  rear,  and  these 
su|iports  should  be  adjusted  to  share  the  load  evenly. 

The  operating  mechanism  should  be  checked  and 
adjusted.  Especially  is  this  im|)ortant  with  the  hand- 
operated  circuit  breakers.  The  remote  control  me- 
chanisms should  be  so  arranged,  if  possible,  that  the 
connecting  rods  are  in  tension  when  closing.  The 
mounting  bolts   of   the   bell    crank   bearings   should    be 


394 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


well  embedded  in  their  foundation.  A  large  washer  or 
plate  should  be  put  under  the  head  to  give  extra 
strength  to  their  setting  in  the  concrete.  If  the  force 
to  close  the  circuit  breaker  is  such  as  to  tend  to  pull 
the  bell  crank  bearing  loose,  adjustment  should  be 
made  by  means  of  the  set  screw  on  the  circuit  breaker 
frame  and  the  correct  proportioning  of  the  connecting 
rods.  If  the  screw  is  out  too  far,  it  will  prevent  the 
circuit  breaker  from  closing.  In  attempting  to  force 
the  circuit  breaker  closed,  the  operator  may  thus  pull 
up  the  bell  crank  bearings  or  break  the  closing  handle. 
It  is  important  also  that  this  set  screw  be  not  in  too 
far;  otherwise  the  travel  will  be  too  great  and  will  in- 
jure the  contacts. 

Before  the  circuit  breaker  is  put  into  service,  it  is 
important  to  see  that  the  brushes  make  good  contact, 
thus  preventing  trouble  from  heating  and  arcing.  Ad- 
justment of  the  brushes  is  sometimes  necessary,  espe- 
cially in  repair  work.  These  adjustments  can  easily 
be  made  by  moving  the  contacts  slowly  in  and  out  and 
noting  if  the  moving  contacts  press  well  against  the 
stationary  contacts. 

The  structure  for  supporting  the  cirucit  breakers, 
whether  masonry  or  pipe,  should  be  erected  complete 
before  any  apparatus  is  mounted  thereon.  In  erecting 
the  cell  structure,  provision  must  be  made  for  all  neces- 
sary openings.  The  conduit  for  instrument  and  con- 
trol wiring  must  all  be  put  in  and  the  mounting  bolts 
for  bus-bar  supports,  disconnecting  switches,  trans- 
formers, etc.,  be  in  place  before  the  concrete  or  brick 
work  is  completed,  as  considerable  trouble  and  expense 
will  be  involved  if  an  attempt  is  made  to  do  such  work 
after  the  completion  of  the  masonry  structure. 

MKTIIOD   OF   INSTALLING   CONNECTIONS 

The  method  and  type  of  construction  used  in  mak- 
ing the  connections  between  the  various  machines  de- 
pends upon  the  design  of  the  building.  If  the  station 
:s  provided  with  a  basement,  the  connections  are  run 
underneath  the  floor,  either  in  conduit  or  open  and 
supported  from  the  basement  ceiling.  Fig.  3  shows  -i 
substation  with  a  basement,  in  which  all  main  leads 
are  run  open,  supported  from  the  basement  floor.  The 
small  wiring  and  control  cable  is  run  in  conduit,  which 
is  supported  from  the  basement  ceiling.  If  the  con- 
nections are  run  in  the  open,  the  leads  should  either 
be  bare  copper  rod  or  strap,  or  flame  proof  insulated 
cable,  except  the  connections  between  the  generator 
and  mill  motor.  These  should  always  be  copper  strap, 
as  the  current  is  too  large  on  this  circuit  for  the  eco- 
nomic use  of  cable. 

In  stations  not  having  a  basement,  either  of  two 
general  schemes  may  be  used.  The  first  provides  for 
running  all  leads,  except  the  tie  circuit  between  genera- 
tor and  mill  motor,  in  conduit  placed  in  the  floor.  The 
tie  circuit  leads  are  run  in  a  trench  cut  in  the  floor. 
This  trench  is  usually  about  two  feet  wide  by  two  feet 
deep.  The  copper  strap  leads  are  supported  on  insu- 
lators mounted  on  cross  pieces  of  iron  pipe  or  channel 


and  are  placed  about  three  inches  from  the  bottom  of 
the  trench  and  extend  three  or  four  inches  into  the 
walls  of  the  trench  on  each  side.  The  construction  of 
this  trench  is  shown  in  section  CC,  Fig.  2.  The  cover 
for  the  trench  is  a  steel  floor  plate.  The  trench  is 
framed  with  an  offset  to  permit  the  cover  to  come  flush 
with  the  station  floor.  The  conduit  for  the  remainder 
of  the  leads  may  be  either  iron  or  fibre,  depending  upon 
the  size  of  leads.  If  the  leads  are  too  large  for  use  in 
one  conduit,  the  alternating-current  leads  may  be  run 
separate  in  individual  fibre  ducts. 

In  the  second  scheme,  trenches  are  cut  in  the  floor. 
All  main  leads  are  of  bare  copper  strap  supported  on 
insulators  mounted  on  channel  iron  or  pipe  similar  to 
that  used  for  the  tie  circuit  described  above.  These 
supports  for  the  insulators  are  mounted  approximately 
three  inches  from  the  bottom  of  the  trench.  The  con- 
duit for  the  small  wiring  and  control  leads  is  laid  in 
the  bottom  of  the  trench.  This  scheme  is  shown  in 
detail  in  Fig.  2. 


FIG.   8 — SECTION   OF  .\   CONTROL  BO.AKD 

Showing   the   resistor  supported    from   the   wall   braces   at 
the  rear  of  the  panel. 

This  second  method  of  installing  the  connections 
has  several  advantages  over  the  first.  It  eliminates 
delay  in  floor  construction  that  might  be  necessitated 
by  not  having  at  hand  sufficient  conduit.  It  facilitates 
the  laying  of  the  conduit,  and  eliminates  difficulties  due 
to  mistakes  in  putting  in  the  wrong  size  or  not  a  suffi- 
cient number.  The  cost  of  installing  the  leads  and 
making  the  trenches  may  be  more,  but  this  cost  is  ofltset 
by  the  time  and  expense  which  might  be  incurred  in 
putting  in  the  wrong  size  or  number  of  conduits,  and 
the  elimination  of  delay  in  making  the  floor. 

The  armature  and  field  leads  of  the  direct-current 
mill  motor  and  the  generator,  and  the  primary  and 
secondary  leads  of  the  alternating-current  motor  for 
the  flywheel  set  are  brought  out  for  external  connec- 
tion under  the  machines.  Therefore,  provision  must 
be  made  in  the  foundation  of  each  one  of  these  ma- 
chines for  making  the  external  lead  connections.  If 
the  station  has  a  basement,  it  is  verj'  simple  to  make 
this  provision.  The  foundation  in  this  case  is  made 
with  pits  under  the  armature  of  each  machine  where 


September,   1921 


THE   ELECTRIC   JOURNAL 


395 


the  leads  come  out.  These  pits  should  be  high* 
enough  to  permit  ample  space  in  which  to  make  the 
cable  or  strap  connections  to  the  machine  leads. 
Enough  supports  must  be  provided  for  supporting  the 
cable  or  strap.  A  doorway  is  made  through  the  foun- 
dation walls  where  the  external  leads  enter.  This 
type  of  foundation  construction  was  used  in  the  sta- 
tion shown  in  Fig.  4. 

In  stations  not  having  a  basement,  the  providing 
of  this  pit  is  not  so  simple.  A  manhole  must  be  made, 
either  where  the  leads  enter  through  the  foundation  or 
at  some  other  point,  of  sufficient  dimensions  to  permit 
access  to  the  pit.  The  pit  need  not  be  so  large,  but  it 
should  be  of  ample  size  to  permit  a  workman  room  to 
move  around  with  ease.  I'he  station  shown  in  Fig.  2 
uses  this  type  of  construction. 

METHOD    OF    TERMINATING    CONDUITS    AT    SWITCHBOARD 
AND  CONTROL  PANELS 

The  method  of  terminating  the  conduits  in  the 
rear  of  the  switchboard  and  the  control  panel  recjuires 
consideration  to  obtain  a  neat  job.  To  accomplish  this 
is  an  essential  part  of  the  construction  work  which 
cannot  be  slighted.     It  is  necessar}-  in  good  construe- 


Coping  for  Conduit  Bends 


^^mMiMM^if^^m^M 


tion  work  that  these  conduits  terminate  uniformly  in 
height  and  in  a  straight  line  back  of  the  board.  The 
elbow  bends  should  be  embedded  in  the  floor  with  only 
the  straight  part  of  the  conduit  extending  above.  In 
thick  floors  or  ground  floors,  it  is  very  easy  to  keep  the 
elbows  embedded,  but  with  thin  floors  this  is  im- 
possible. Therefore,  to  avoid  having  the  elbows  ex- 
lending  above  the  floor,  two  general  schemes  have  been 
more  or  less  adapted  as  standard  construction  for  this 
work. 

The  most  common  method  is  to  provide  a  coping 
of  sufficient  height  to  cover  the  elbows,  this  coping 
to  extend  the  length   of  the  board.     Fig.    10  shows  a 


section  through  the  board  with  the  conduits  embedded 
in  a  coping  extending  two  inches  above  the  floor.  The 
height  of  this  coping  is  sufficient  only  for  instrument 
and  control  wire  conduits  up  to  one  inch  diameter. 

Another  method  of  construction  sometimes  used 
is  to  provide  a  trench  in  the  rear  of  the  board  and  ex- 
tending its  entire  length.  This  trench  should  be  about 
four  inches  deep  and  from  six  to  eight  inches  wide. 
The  conduits  to  the  board  terminate  in  this  trench, 
and  no  elbows  are  required.  The  trench  is  covered 
with  sheet  steel  plates  having  a  series  of  one  inch  holes 
drilled  in  them,  which  are  provided  with  conduit  bush- 
ings, as  shown  in  Fig.  9.  The  cable  as  they  come  out 
of  the  conduits  are  pulled  up  through  the  holes  and 
connected  to  the  board.  In  this  arrangement  no  con- 
duit extends  above  the  floor. 

CONCLUSION 

In  reviewing  the  preceding  discussion,  one  may 
question  why  such  particular  attention  should  be  paid 
to  the  selection,  design  and  installation  of  the  equip- 
ment and  station  for  a  reversing  mill  motor.  This 
question  arises  doubtless  due  to  failure  to  appreciate 
the  importance  of  this  type  of  mill,  with  respect  to 
the  output  of  the  entire  plant.  A  blooming  mill  feeds 
steel  for  every  other  mill  in  the  plant.  It  is  through 
this  mill  that  the  ingot,  cast  direct  from  the  furnace 
metal,  must  pass  before  it  can  reach  the  billet,  struc- 
ture, rail,  slab,  sheet  mill,  etc.,  and  from  these  to  the 
various  finished  products.  It  is  evident,  therefore, 
that  if  a  blooming  mill  is  shut  down  for  any  length 
of  time,  the  output  of  the  plant  is  decreased  thereby. 
It  is  in  driving  this  type  of  mill  that  the  electric  motor 
shows  its  greatest  superiority.  The  importance  of 
this  mill  makes  advisable  every  reasonable  precaution 
to  guard  against  its  failure  to  operate  continuously. 
This  means  not  only  a  reliable  motor  but  a  perfect  in- 
stallation. It  is  just  as  essential  that  the  auxiliary 
equipment  be  reliable  as  it  is  for  the  motor.  The. 
failure  of  some  small  relay,  switch  or  connection  will 
close  the  mill  down  just  as  quickly  as  the  failure  of 
the  motor.  Not  to  realize  this  important  fact  is  liable 
to  lead  to  disastrous  results.  Care  in  all  details  is 
required  for  a  properly  designed  station,  using  the  best 
of  equipment  and  most  reliable  forms  of  installation 
and  construction. 


Electric  Furnace  Gray  Iron 

JAS.    L    CAWTHON,   JR. 

.Metallurgist, 
Pittsburgh   Electric  Furuacc  Corporation 


THE  sponsors  of  the  developmeiU  of  an>-  revolu- 
tionary innovation  which  has  to  do  with  indus- 
trial production  processes,  almost  invariably 
meet  with  most  tenacious  opposition  and  serious  diffi- 
culty. The  history  of  the  iron  and  steel  industry's  de- 
velopment during  the  past  century  is  largely  a  chronicle 
of  the  fight  which  men  like  Besserner,  Siemens, 
Marten,  Tropenas,  Hadfield  and  others  waged  in  secur- 
ing recognition  and  adoption  of  their  inventions. 
Among  the  radical  inventions  growing  out  of  the  de- 
velopment of  the  iron  and  steel  making  processes,  the 
electric    furnace   has  been   bv    far   the   most   fortunate 


Having  qualified  from  the  standpoint  of  quality 
and  also,  from  the  important  one  of  economy,  the  elec- 
tric furnace  is  now  establishing  itself  in  the  gra\-  iron 
foundry. 

IX'OXOMIKS 

The  matter  of  cost  is  one  which  presents  itself  for 
consideration  primarily  and  is  of  c(nirse  a  factor  of 
controlling  importance  in  many,  if  not  the  majority,  of 
cases.  There  are  few  localities  in  the  Inited  .'states 
where  the  direct  conversion  cost  per  ton  of  melting  in 
the  electric  furnace  is  not  higher  than  the  same  figures 
for    cupola    operation.     I'y    direct    conversion    cost    is 


with  respect  to  the  rapidity  with  which  it  has  come  meant  the  cost  of  one-sixth  or  one-seventh  of  a  ton  of 
to  be  recognized  as  an  accepted,  reliable  and  practical  coke,  jjIus  blower  jxnver,  plus  direct  labor  and  refrac- 
melting  and  refining  medium.  lories   and  meltiiig   losses    for   the   cupola  ;   500  to   550 


The  c  o  ni  - 
mercially  s  u  c  - 
cessful  electric 
furnace  is  less 
than  twenty- 
five  years  old ; 
but  there  a  r  e 
hundreds 
of  them  at  work 
in  the  United 
States  alone, 
while  in  luiro- 
pean  countries 
like  Sweden  and 
Switzerland, 
where  underly- 
i  n  g  economic 
conditions  are  so 
exceptionally 
propitious  for 
the  electric  fur- 
nace, the  ma- 
jority of  all  fer- 
rous melting  and 
even  smelting,  is 
carried  on  with 
electricity-.  The 
el    e  c  t  r  o  - 


—  woo  roUNn.  three  electkode,    llv  .  .,i  ..i.., i     ilk.n.xle    i.\    the    works 

QUEEN   CITY    FOUNUARV   CO.,  DENVER,  tOI-0. 

Producing  gray  iron  ca.stings.    The    furnace  is  charced  to  6-;oo  ijounds. 


kw-hr.  plus  six- 
teen ])()unds  of 
c  a  r  b  o  n  c  1  e  c- 
trodcs  plus 
labor  and  re- 
fractories and 
melting  loss  for 
llic  electric  ftir- 
iiace ;  and  inter- 
est .111(1  deprecia- 
tion or  mainten- 
ance   for   l)olh. 

W  i  t  h  basic 
piiccs  (if  $10 
(.'(ike  laid  down 
and  [Miwer  at  1. 5 
cents  ]ier  kilo- 
watt-liour,  these 
respective  con- 
version costs 
have  the  average 
ni  eight  to  ten 
ddUars  for  the 
c  u  p  o  1  a  and 
twelve  to  four- 
teen dollars  for 
the  electric  fur- 
nace under  aver- 


metallurgical  furnace  may  then  be  rightly  considered  as  age  cost  conditions  east  of  the  Mississippi  River, 
well  established  in  the  m'etal  industries.  These  figures  are  purely  on  a  cost  competitive  basis. 
Its  debut  was  made  m  the  tool  and  alloy  steel  taking  no  cognizance  of  the  advantages  of  either  pro- 
fields,  where  the  product  had  a  margin  sufficient  to  cess,  one  way  or  the  other  or  of  conditions  preva.hng 
withstand  the  melting  cost  which  was  high,  due  to  the  in  many  locations  where  coke  is  extremelv  high  or  elec- 
inefficiencv  of  the  furnace  as  then  designed.     Success  Iric  power  unusually  low. 

in  these  'fields,  together  with  increased  rapidity  of  Thus  the  savings  to  accrue  trom  the  electric  fur- 
melting  and  efficiency  in  furnace  design,  led  to  its  nace  are  not  usually  to  be  expected  or  realized  in  the 
adoption  in  the  steel  casting  industry. 


direct  conversion  costs,  cupola  versus  electric.     There 


September,  1921 


THE    ELECTRIC   JOURNAL 


397 


is,  however,  a  means  of  actually  producing  metal  in 
the  ladle,  ready  to  pour,  with  the  electric  furnace  more 
cheaply  than  cupola  iron  in  the  same  condition.  This 
is  true  as  a  consequence  of  the  difference  in  the  cost 
of  the  raw  materials  forming  the  cupola  charge  and 
the  electric  furnace  charge.  While  the  conversion 
cost  in  the  electric  is  higher,  the  diiiference  in  the  cost 
of  charge  for  the  cupola  and  electric  is  almost  invari- 
ably sufficient  to  more  than  offset  the  disparity  in  melt- 
ing cost. 

A  word  of  explanation  is  needed  here.  With  the 
cupola,  it  is  not  possible  to  make  good  castings  from  a 
charge  made  of  one  hundred  percent  scrap ;  and  such 
grades  of  scrap  as  cast  iron  borings,  steel  turnings, 
very  light  drop  forge  flashings,  punchings,  clippings, 
etc.  are  considered  entirely  out  of  the  question  as  to 
utilization  in  cupola  mixes.  The  rapid  type  electric 
furnace  is;   in   several   sections  of  the  I'nited   States; 


SLIDE     VALVE      SEAT- 
MANHOLE   COVER 


FIG.    2 — COMPLICATED    GRAY    IRON    CASTINGS    MADE    FROM    IRON    AND 
STEEL   SCRAP   WITH    NO   PIG    IRON 

making  an  excellent  grade  of  gray  iron  castings  from 
charges  composed  of  sprues,  gates,  risers,  (the  returns 
from  the  casting  floor),  mixtures  of  borings,  turnings, 
flashings  and  other  very  light  iron  and  steel  scrap. 
The  work  done  by  the  foundries  employing  the  elec- 
tric furnace  is  not  confined  to  any  one  grade  or  class 
of  castings,  but  is  general  in  its  scope.  It  includes 
very  low  priced  work  such  as  grate  bars,  cast  water 
pipe  and  high  grade  work  like  piston  heads,  locomo- 
tive cylinders,  fine  light  work  such  as  small  valves  and 
automobile  piston  rings,  and  special  hard,  tough  iron 
like  chilled  rolls  and  wearing  plates.  The  illustrations 
give  a  general  idea  of  the  wide  varieties  of  castings 
produced.  The  foundry  which  made  the  parts  shown 
originally  installed  the  furnace  for  the  purpose  of  mak- 
mg  steel  castings,  subsequent  trials  demonstrating  it 
to  be  economical  to  shut  down  their  cupola  and  pour  all 
castings,  both  iron  and  steel,  from  the  electric  furnace. 

COMPARISON  OF  PROCESSES 

It  has  been  a  generally  held  precept  in  the  iron 


casting  industry  that  "all  scrap"  mixes  were  incapable 
of  producing  high  grade  castings;  and  some  pur- 
chasers, even  at  the  present  time,  specify  that  no  scrap 
shall  be  used,  when  purchasing  particularly  high  grade 
castings.  This  evokes  the  question  as  to  the  ability  of 
the  electric  furnace  to  convert  all  scrap  charges  into 
high  grade  gray  iron  castings.  With  years  of  experi- 
ence in  cupola  foundry  work,  the  man  who  has  "served 
his  time"  usually  has  a  deep  seated  idea  that  the  pro- 
posal to  manufacture  good  castings  from  all  scrap 
charges  is  preposterous,  regardless  of  final  analysis  ob- 
tained. His  experience  with  the  cupola  has  naturally 
developed  such  an  attitude  aS  a  result,  in  all  proba- 
bility, of  grievous  and  costly  experience.  Analysis  of 
the  two  melting  processes  clears  the  question. 

When  the  cupola  is  prepared  for  the  day's  melt  a 
small  amount  of  wood  is  placed  on  the  hearth  and  a 
bed  of  coke  laid  on  top  of  this.  Alternate  layers  of 
coke  and  iron  are  then  piled  in  until  the  charge  is  com- 
pleted. When  the  fire  is  started  and  the  blast  turned 
en,  as  the  iron  becomes  heated  it  melts  and  drops  down 
onto  the  hearth.  When  a  sufficient  quantity  of  iron 
for  tapping  is  collected  in  the  bottom  of  the  shaft,  it 
is  drawn  off  and  poured  into  the  flasks.  During  the 
melt  the  iron  is  continually  in  close  and  intimate  con- 
tact with  the  coke,  ash  and  fluxes.  It  is  unreasonable 
to  expect  that  the  iron  would  do  otherwise  than  absorb 
slag  and  the  impurities  of  the  coke,  the  chief  one  of 
these  being  sulphur.  This  happens  with  unfailing 
regularity  to  the  consequent  detriment  of  the  molten 
metal.  In  operation,  if  the  cupola  charges  have  an  av- 
erage sulphur  content  of  0.05  percent,  the  metal  as 
tapped  will  analyze  for  sulphur  0.07  to  o.ii  percent. 
This  is  serious  enough,  but  the  metal  is  further  in  con- 
tact with  the  air  blast  used  in  the  combustion  of  the 
coke.  This  blast  has  a  decidedly  oxidizing  effect  on 
the  metal  and  is  said  to  account  for  the  sparkling  of 
the  iron  when  it  is  tapped,  due  to  inclusions  of  oxides. 
It  is  certainly  true  that  it  is  possible  to  oxidize  metal  by 
the  blast,  and  metal  melted  in  the  cupola  and  then  re- 
fined in  the  electric  furnace  has  different  character- 
istics from  the  metal  as  it  comes  from  the  cupola.  The 
consequence  is  that,  with  the  utmost  care,  iron  melted 
in  the  cupola  is  more  or  less  oxidized  and  has  slag  and 
other  impurities  in  it. 

The  cupola,  in  so  far  as  definite  chemical  control 
of  melted  iron  is  concerned,  is  a  hit  or  miss  affair.  It 
is  estimated  a  certain  percentage  of  alloys  such  as 
manganese  and  silicon  will  be  burned  out;  but  it  is  im- 
possible to  predict  with  regularity  what  the  analysis 
of  the  molten  metal  will  be.  Definite  control  of  the 
total  carbon  and  of  the  graphitic  and  combined  carbon 
as  a  function  of  silicon,  manganese  and  other  alloy  con- 
tents is  therefore  an  impossibility.  This  is  accentu- 
ated by  the  fact  that  once  the  iron  is  melted  there  is  no 
practical  way  of  correcting  deficiencies  in  the  analysis 
of  the  molten  metal.  The  iron  must  then  be  poured 
into  moulds  or  pigged,  it  being  a  matter  of  choosing 


398 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


the  lesser  of  tw(j  evils  as  to  which  course  will  be  pur- 
sued, if  the  metal  is  not  right.  These  are  inherent  de- 
ficiencies of  the  cupola;  but  it  is  not  the  purpose  or 
intention  of  this  article  to  in  any  way  decry  the  cupola. 
It  is  an  old,  proven  and  efficient  melting  apparatus; 
and  its  shortcomings  are  alluded  to  only  for  the  pur- 
pose of  comparison  with  the  electric  furnace  and  ex- 
plaining why  electric  gray  iron  is  superior  to,  and  often 
cheaper  than,  the  cupola  product. 

In  preparing  the  charge  for  the  electric  furnace, 
material  is  selected  which  gives  a  resultant  mixture  as 
close  to  the  specification  of  the  finished  metal  as 
possible.  The  furnace  being  charged,  the  electrodes 
descend  on  the  scrap  and  the  arc  forms.  From  then 
on  the  metal  is  heated  and  melted  by  the  radiation  and 
direct  play  of  the  arcs  alone.  There  is  no  fuel  for  the 
metal  to  be  in  contact  with,  and  there  is  no  pick  up  of 
sulphur.  With  the  basic  furnace,  sulphur  can  be  re- 
duced to  0.02  to  0.009  percent  with  regularity  and  cer- 
tainty. No  blast  is  necessary  and  the  furnace  is  kept 
sealed  as  tightly  as  is  practicable.  At  no  time  of  the 
heat,  unless  it  is  desired,  is  the  metal  in  contact  with  an 
oxidizing  atmosphere.  If  a  small  amount  of  coke  be 
thrown  on  top  of  the  charge,  a  thoroughly  reducing 
condition  of  atmosphere  is  easily  maintained  in  the  fur- 
nace hearth. 

In  melting,  the  metal  does  not  flow  down  over  a 
bed  of  coke  but  collects  on  the  hearth  of  the  furnace  as 
melted  and  remains  "dead."  It  therefore  has  no 
tendency,  of  a  nature  comparable  to  that  in  the  cupola, 
to  absorb  extraneous  matter. 

The  comparison  of  these  two  melting  conditions 
suffices  as  an  explanation  of  the  superiority  of  eleictric 
gray  iron  castings  over  cupola  iron.  The  action  of 
the  electric  furnace  is  refining  and  degasifying  during 
the  whole  process,  whereas  cupola  action  is  con- 
taminating and  oxidizing  for  the  great  majority  of  the 
time.  The  ability  to  deoxidize  and  thoroughly 
scavenge  the  iron  is  the  only  plausible  reason  for  the 
ability  of  the  electric  furnace  to  make  an  excellent 
grade  of  castings  from  mixtures  of  100  percent  scrap, 
analysis  for  analysis. 

The  iron  foundryman  is  coming  more  and  more 
to  realize  the  desirability  and  necessity  of  chemical 
control.  This  is  partly  a  result  of  his  own  realization 
of  its  desirability  and  wisdom,  and  is  partly  the  result 
of  the  increasing  tendency  to  place  contracts  on  a 
specification  basis.  In  this  way  also  the  electric  fur- 
nace has  the  advantage.  It  was  mentioned  that  there 
are  no  means  of  correcting  deficiencies  in  the  molten 
metal  from  the  cupola.  In  the  electric  furnace  when 
melting  is  completed  and  the  metal  is  presumably  right 
for  tapping,  a  sample  bar  can  be  poured  and  judged 
from  fracture  or  an  actual  analysis  can  be  made.  If 
the  metal. is  deficient  in  any  respect,  additions  of  alloys 
or  reductions  of  them  can  be  made  to  re-adjust  the 
analysis  and  bring  it  to  the  particular  point  desired. 
The  elements  of  uncertainty  are  eliminated,  even  when 


using  mixes  composed  entirely  of  miscellaneous  scrap. 

USE  OF   STEEL 

It  is  a  well  established  fact  that  percentages  of 
steel  in  gray  iron  charges  are  of  decided  influence  in 
closing  up  the  grain  structure  of  gray  iron  and  in  mak- 
ing a  tough,  shock-resisting  metal.  This  use  of  steel 
in  the  cupola  is  attended  by  hardness  of  castings,  un- 
less silicon  be  added,  which  is  usually  accomplished 
by  including  percentages  of  high  silicon  pig  in  the 
charge.  This  is  very  expensive.  In  using  steel  in  the 
electric  furnace,  the  silicon  is  supplied  to  the  bath  in 
the  form  of  50  percent  ferro-silicon  and  is  attended  by 
practically  100  percent  efficiency  of  absorption.  There 
is  never  any  danger  of  producing  hard  iron  when  using 
steel  in  the  electric  furnace  charges.  For  the  purpose 
of  giving  the  steel  the  necessary  carbon  content  when 
used  in  the  electric  furnace,  small  percentages  of  coke 
are  added  with  the  steel.  This  is  usually  in  the  ratio 
of  about  70  lbs.  of  coke  to  the  ton  of  steel  in  the 
charge.     In  melting,  the  steel  absorbs  carbon  from  the 


FIG.    3 — GR.VY   IRON    PIPE  CASTINGS    M.^DE  FROM    IKO.V   .\.ND  STEEL 
SCRAP   WITH    NO   PIG   IRON 

coke  in  proportion  to  the  amount  of  coke  present,  the 
intimacy  of  the  coke-steel  content  or  mixture,  the  de- 
gree of  temperature  and  the  time  of  association.  Thus 
it  is  practicable  to  make  a  most  excellent  grade  of  gray 
iron  from  charges  composed  entirely  of  such  materials 
as  steel  turnings.  One  plant  located  at  Livet,  France, 
produced  more  than  500000  tons  of  high  strength  iron 
castings  by  this  method  during  the  war.  Their 
charges  were  composed  entirely  of  steel  turnings  with 
small  percentages  of  coke.  It  is  reported  that  the 
cost  of  the  metal  in  the  ladle  at  that  plant  was  about 
one-half  that  of  cupola  melted  iron  for  the  same 
locality. 

TEMPERATURE  CONTROL 

When  iron  melts  in  the  cupola  it  rapidly  drops  to 
the  hearth.  For  this  reason  the  matter  of  real  super- 
heating in  the  cupola  is  an  extremely  difficult  one.  It 
cannot  be  consistently  and  regularly  achieved. .  The 
metal  drops  away  from  the  heating  zone  too  rapidly  to 
obtain  the  degree  of  superheat  desired. 


September,   1921 


THE   ELECTRIC   JOURNAL 


399 


The  temperature  of  the  electric  furnace  is  only 
limited  by  the  melting  point  of  the  refractory  lining. 
This  is  much  higher  than  any  temperature  desired  for 
gray  iron,  even  in  the  most  difficult  castings.  The 
electric  furnace  can  make  iron  of  temperatures  such 
as  are  by  no  means  desirable  nor  recommended.  How- 
ever, it  is  also  true  that  temperatures  such  as  are  not 
consistently  obtainable  in  the  cupola  are  desirable  in 
gray  iron  casting  work  and  contribute  to  the  strength 
and  quality  of  the  castings. 

The  matter  of  pouring  temperatures  has  been 
given  thorough  investigation;  and  it  has  been  proven 
that  temperatures  from  100  to  150  degrees  higher  than 
that  usually  obtained  in  cupola  melted  iron  materially 
improve  the  strength  and  grain  structure  of  the  metal. 
A  maker  of  soil  pipe  reports  that  besides  decided  in- 
crease in  strength,  he  has  also  been  able  to  increase 
the  specific  gravity  of  the  metal  ten  percent  by  the  use 
of  the  electric  furnace.  This  is  a  most  positive  in- 
dication of  increased  fluidity,  soundness,  tightness,  and 
metallic  continuity  of  the  castings. 


FIG.  4 — LOCOMOTIVE  CYLINDER  CASTINGS  MADE  FROM  ELECTRIC  FUR- 
NACE GRAY   IRON 

The  temperature  control  obtainable  with  the  elec- 
tric furnace  permits  these  higher  temperatures  with 
consistency  and  regularity.  They  allow  the  use  of  low 
phosphorus  iron  for  many  castings  which,  when 
cupola  produced,  require  high  phosphorus  metal.  The 
sole  function  of  phosphorus  in  iron  is  to  impart  fluidity 
to  the  molten  metal.  This  is  accomplished  at  the  ex- 
pense of  toughness,  strength  and  fineness  of  grain. 
Thin,  light  sections  in  castings  have  required  the  use  of 
high  phosphorus  metal  in  the  cupola,  but  the  most  deli- 
cate and  intricate  shapes  can  be  and  are  produced  ' 
the  electric  furnace  with  very  low  phosphorus  ir  ,; 
An  example  of  this  is  the  individually-cast  piston  r  ■  _■ 
which  is  being  made  in  the  electric  furnace  with  v>ji\ 
low  phosphorus  iron  with  a  loss  from  cold  shuts  of  less 
than  five  percent.  These  rings  are  cas,t  so  nearly  to 
shape  that  the  finishing  done  on  them  is  reduced  to  a 
minimum. 

QUALITY  CONSIDERATIONS 

There  is  an  increasing  demand  for  a  grade  of  iron 
so  far  superior  to  the  metal  of  ordinary  cupola  quality 
that  its  production  is  coming  to  be  recognized:  as  essen- 
tially an  electric  furnace  process.  Reference  is  had 
to  high  pressure  steam  fittings,  and  to  extremely  fine 


grained,  high  tensile  strength,  long  wearing  iron  for 
locomotive  and  other  cylinders,  pistons,  valve  bodies, 
gasoline  motor  cylinders,  ammonia  cylinders  and 
siinilar  work.  The  difficulty  in  producing  such 
grades  of  castings  is  largely  one  of  getting  an  iron 
which  is  easily  machinable  and  still  absolutely  free 
from  blow  holes.  Sulphur  gives  molten  iron  a  blow- 
ing tendency,  especially  if  not  superheated,  as  well  as 
reducing  the  machinability.  At  least  three  valve  body 
foundries,  two  locomotive  cylinder  makers,  and  three 
piston  ring  factories  have  realized  the  great  advantage 
of  the  electric  furnace  for  such  work  and  have  in- 
stalled it.  These  concerns  have  not  only  been  able  to 
solve  their  melting  problems  but  have  effected  marked 
cost  savings  by  the  regular,  judicious  use  of  all-scrap 
charges. 

Electric  furnace  iron,  besides  exceptional  strength, 
has  decided  resistance  to  impact.  This  characteristic 
is  an  important  one,  since  it  really  places  at  the  dis- 
posal of  the  designing  engineer  a  new  metal  to  work 
with.  In  the  design  of  machines,  such  as  agricultural 
implements,  road  machinery,  motor  cars,  tractors,  etc., 
many  parts  must  be  specified  to  be  of  malleable  iron 
for  the  purpose  of  giving  them  shock  and  impact  re- 
sistance; but  they  often  require  a  very  decided  amount 
of  rigidity,  which  the  normal  cross-section  of  the  part, 
as  cast  from  malleable  iron,  would  not  possess  in  the 
degree  desired  and  considered  necessary.  The  de- 
signer must  consequently  increase  the  section,  fre- 
quently from  200  to  300  percent  of  the  normal  area, 
for  the  sole  purpose  of  adding  rigidity.  This  is  ob- 
viously undesirable  and  expensive.  Electric  furnace 
iron  can  be  used  to  replace  malleable  iron  in  many  of 
these  applications  with  superior  results,  to  say  nothing 
of  economy.  The  designing  engineer  will  thus  find  a 
new  metal  at  his  disposal  for  such  work  and  in  many 
instances  will  be  able  to  replace  the  expensive  malle- 
able iron  with  the  superior  grades  of  electric  gray 
iron  produced  by  the  electric  furnace. 

As  an  indication  of  what  can  regularly  be  expected 
{rum  electric  furnace  iron,  one  user  reports  tensile 
strengths  up  to  62  000  lbs.  for  iron  made  from  all  scrap 
charges.  Still  another  reports  an  average  of  5100  lbs. 
transverse  strength  with  a  maximum  of  6200  and  a 
minimum  of  4U00  lbs.  The  bars  tested  were  taken  . 
fiom  12  successive  heats  from  charges  of  gray  iron 
i-'imgs  and  axle  turnings.  An  average  analysis  is 
given:  carbon,  3.20  percent,  sulphur  0.05  percent, 
phosphorus  0.25  percent,  manganese  o."-:^  oercent,  sili- 
con 2.10  percent.  No  panicuiar  difference  in  thi- 
analysis  ti.„:i;  ••rdinary  cupola  metal  exists  e.N.cei)t  u._- 
the  sulphur  is  lower  than  ordinary,  due  to  the  absence 
of  sulphur  pick-up  in  the  electric  furnace  and  to  the 
dilution  with  low  sulphur  steel.  The  phosphorus  is 
also-lower  as  a  result  of  the  latter  cause.  In  each  case 
the-  "melt  down"  silicon  was  approximately  1.25  per- 
cent. Sufficient  ferrosilicon  was  then' added  to  bring 
the  analysis  to  2.00  to  2.25  percent. 


400 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  $ 


The  greatest  disadvantage  of  the  electric  furnace 
is  the  first  cost  of  the  installation.  Under  favorable 
and  proper  conditions  this  is  offset  by  the  fact  that, 
if  the  furnace  is  kept  busy  and  charges  are  judiciously 
selected,  the  net  savings  on  the  cost  of  iron  in  the  ladle 
will  allow  the  furnace  to  pay  for  itself,  usually  within 
a  year's  time  or  less.  This  generally  applies  to 
localities  with  power  rates  up  to  2.5  cents  per  kw-hr. 
The  electric  furnace  has  a  life  of  from  12  to  25  years 
with  reasonable  care. 

In  selecting  a  furnace,  it  is  advantageous  to  adopt 
a  rapid  operating  furnace  just  sufficiently  large  to  take 
care  of  the  foundry's  maximum  output  on  a  10,  12  or 
24  hour  melting  basis,  with  reasonable  allowance  for 
expansion.  An  economical  furnace  for  a  gray  iron 
foundry   should  be  capable  of   making  a  heat   in  one 


hour's  time  and  should  be  capable  of  being  overloaded 
200  to  300  percent  for  large  castings.  Conversion 
costs  in  the  electric  furnace  are,  other  things  being 
equal,  in  general  proportion  to  the  amount  of  time  re- 
quired to  complete  a  furnace  cycle,  i.e.,  from  tap  to 
tap.  Unless  this  type  of  operation  be  contemplated, 
the  figures  given  in  this  article  would  hardly  apply. 
Such  a  furnace  should  have  a  suitable  adjustment  of 
voltages  for  melting  and  refining  rapidly  and  efficiently. " 

It  is  by  no  means  the  intention  to  convey  the  im- 
pression that  the  electric  furnace  is  going  to  supplant 
the  cupola  everywhere  at  once.  It  is  beginning  to  find 
its  field  in  the  gray  iron  and  malleable  iron  foundries, 
just  as  it  has  already,  in  large  measure,  done  in  the 
tool  steel,  rolling  mill  and  steel  foundry  industries.  In 
doing  this  it  is  naturally  supplanting  some  cupolas. 


Fir  si  Hevorsi  np;  Mill  Drive  in  Ttm  CoTij^iry 


W.  S.  HALL 

Electrical   Engineer,   Illinois   Steel   Company, 
Vice-President  A.  I.  &  S.  E.  E. 


IN  VIEW  of  the  fact  that  a  large  number  of  motor- 
driven  mills  have  been  installed  in  the  last  few 
years,  it  may  be  of  interest  to  learn  something  of 
the  history  and  development  of  this  type  of  drive  in 
this  country. We  have  all  heard  more  or  less  concerning 
the  design  and  physical  layouts  of  the  newer  installa- 
tions. So  successful  have  they  been  that  this  type  of 
drive  has  become  generally  rccd.uni/A'd  a^  -lanilanl  for 


75  hp  compound  motor  was  geared  to  a  small  two  high 
roll  train,  and  steel  was  rolled  successfully.  The  re- 
sults of  this  experiment  convinced  those  concerned  that 
a  mill  drive  of  this  type  could  be  developed.  The  uni- 
form demand  on  the  power  station,  together  with  the 
small  transmission  and  standby  losses,  made  the  pro- 
position very  attractive  as  compared  with  the  steam 
rcvrriiv,:    r-ill    t'lfi    in    ';ervice.     Equipment    for  a   30 


FIG.     I— THE    FIRST    REVERSING     MILL    MOTOR    INSTALLED    IN     THIS    COUNTRV 


reversing  mills.  The  following,  therefore,  is  not  given 
with  a  view  of  comparing  the  first  drive  of  this  type 
with  those  now  being  installed,  but  to  give  some  record 
of  the  performance  of  the  first  mill  of  this  type  in  this 
country,  which  has  been  in  almost  continuous  opera- 
tion since  its  installation  nearly  fifteen  years  ago. 

The  first  drives  of  this  type  were  installed  in 
Europe  in  1906.  However,  about  the  same  time  some 
experiments  were  carried  on  by  the  engineers  of  the 
Illinois  Steel  Company,  using  a  25  hp,  250  volt,  com- 
pound-wound motor,  driving  a  75  hp  compound- 
wound  generator,  direct  connected  to  a  flywheel.     A 


in.  universal  plate  mill  was  therefore  purchased  in 
1906,  and  put  in  9peration  in  1907. 

The  general  specifications  covering  the  equipment, 
which  is  still  in  operation  today,  were  as  follows  :— 

Motor-Generator  Set— Moior  1300  hp  continuous; 
three-phase,  25  cycle,  375  r.p.m. ;  generator  2000  kw 
normal,  6500  kw  maximum;  voltage  600;  weight  of 
flywheel  100  tons. 

Roll  Motors— Two  on  one  shaft,  maximum  speed 
full  field  100  r.p.m.;  maximum  speed  weak  field  150 
r.p.m. ;  voltage  575 ;  maximum  output  8000  hp. 

The   first   steel   was   rolled   in  July,   1907.     Soon 


September,  1921 


THE   ELECTRIC   JOURNAL 


401 


after  the  mill  was  in  operation,  opportunity  was  af- 
forded to  obtain  satisfactory  data  for  such  corrections 
in  design  as  might  be  necessary,  there  being  practically 
no  such  data  available  at  the  time  the  equipment  was 
built. 

After  a  few  months  of  operation,  experiments 
were  made  which  showed  that  the  commutation  on  the 
generator  could  be  somewhat  improved  by  increasing 
the  compensating  winding.  This  additional  winding 
was  installed  during  the  latter  part  of  1909.  Installa- 
tion of  this  additional  winding  was  the  only  change 
in  the  original  design  which  was  found  necessary.  In 
1917  a  liquid  type  slip  regulator  was  installed  to  take 
the  place  of  the  step-by-step  type  originally  furnished. 
This  was  done  not  only  to  improve  the  operation  from 
the  standpoint  of  uniform  power  station  demand,  but 
also  to  provide  additional  space  for  substation  equi^ 
ment,  the  liquid  type  regulator  being  very  compact  as 
compared  with  the  grid  resistance  originally  installed. 


FIG.   2 — LIQUID   TYPE   SLIP   REUUL.'MOR 

Installed  to  replace  notching-in  relay  control. 

Curves  of  the  alternating-current  motor  while  operat- 
with  the  original  regulator,  and  also  while  operating 
V  ith  the  liquid  type  regulator,  are  given  in  Fig.  3. 

The  following  is  a  detailed  summary  of  the  major 
delays  between  1907  and  1921 : 

Nov.  loth,  1907,  mill  was  shut  down  for  one  week 
to  correct  generator  armature  cross  connection. 

Oct.  14th,  1908,  mill  shut  down  to  try  out  spare  ar- 
mature which  had  been  purchased. 

Sept.  I2th.  1909,  changed  generator  armature  on  ac- 
count of  grounded  coils. 

Oct.  24th,  1909,  trouble  with  generator  armature  bars 
coming  unsoldered.     Armature  changed. 

All  of  the  above  delays  occurred  before  the  addi- 
tional compensating  winding  was  installed.  No  furth- 
er delays  were  experienced  until  191 1,  when  a  delay 
of  a  few  hours  was  caused  by  slight  short-circuit  on 
the  commutator  segments  on  one  of  the  roll  motors. 
In  1913  the  mill  was  down  for  approximately  72  hours 
due  to  grounded  roll  motor  coil.  In  1917  the  genera- 
tor  armature   was   changed   on   account   of   a   ground. 


The  sum  total  of  all  these  delays,  including  those  which 
might  be  considered  as  occurring  during  the  develop- 
ment period,  is  approximately  525  hours.  The  entire 
operating  time  since  the  equipment  was  installed,  neg- 
lecting Sundays,  represents  something  over  100,000 
hours,  showing  that  delay  caused  by  the  failure  of  the 
electrical  equipment  was  slightly  less  than  one  half  of 
one  percent  of  the  time,  and  the  major  portion  of  this 
delay  occurred  within  the  first  three  years  of  opera- 
tion. 

It  may  be  of  interest  to  know  something  of  the 
physical  condition  of  this  equipment  at  the  present 
time.  The  original  winding  on  the  roll  motors  is  still 
in  service.  The  original  commutators  on  both  the 
roll  motors  and  generator  are  in  service,  only  about 
1/16  in.  wear  being  apparent  on  the  roll  motors  since 
they  were  installed.  The  generator  commutators  show 
a  reduction  of  about  1/16  in.  every  five  years  due  to 
wear  and  dressing.  The  original  bearings  are  still  in 
service.  Some  wear  on  the  motor-generator  set  bear- 
ings was  noticeable  at  the  end  of  ten  years.  At  this 
time  a  spare  set  of  bearings  was  purchased  to  guaran- 
tee against  bearing  failure,  knowing  that  they  would 
be  required  eventually  due  to  ordinary  wear.  These 
bearings  have  never  been  installed,  very  little  wear  hav- 


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FIG.   3 — POWER   INPUT  TO  FLYWHEEL  SET  FOR  THIRTY  INCH   UNIVER- 
SAL   PL.^TE    MILL 

ing  occurred  during  the  last  five  years  due  to  an  im- 
proved oscillating  device  having  been  installed.  Since 
the  installation  of  this  equipment  something  over 
I  100  000  tons  of  steel  have  been  rolled. 

During  the  last  few  years  the  equipment  has  not 
been  favored  in  any  way  fearing  a  breakdown  due  to 
the  deterioration  of  the  winding  through  age.  As  a 
matter  of  interest  the  tonnage  rolled  during  the  year 
1920  was  the  maximum  ever  rolled,  and  was  nearly  20 
percent  greater  than  that  rolled  during  any  year  of  the 
first  ten  years  of  operation. 

The  experience  outlined  above  shows  that  after 
fifteen  years  of  service  no  definite  conclusion  can  be 
formed  as  to  the  life  of  a  winding  on  this  class  of 
equipment.  Particular  care  has  always  been  given  to- 
ward keeping  the  winding  free  from  oil,  etc.,  which  is 
detrimental  to  the  life  of  any  winding.  The  entire  in- 
stallation has  been  cleaned  and  painted  regularly,  the 
stators  being  moved  over  so  that  both  stators  and  rotors 
could  be  given  a  good  coat  of  paint.  Time  has  always 
been  found  to  do  this  kind  of  work  during  almost  any 
normal  year,  and  we  have  reason  to  believe  that  the 
small  expense  thus  incurred  has  added  considerably 
to  the  life  of  the  equipment. 


Electrical  Transmission  vSo  Coal  Transportation 


HAROLD  W.  SMITH 

General   Engineer, 
Westinghouse  Electric  &  Mfg.  Company 


ELECTRIC  transmission  lines  have  hitherto  been 
built  chiefly  in  connection  with  hydro-electric 
plants,  as  the  water  powers  are  generally  far 
distant  from  the  cities  where  the  energy  is  marketed. 

Their  successful  operation  has  raised  the  question 
as  to  whether  it  is  possible  also  to  locate  steam  power 
plants  at  the  coal  mines,  and  transmit  the  power  over 
electric  transmission  lines  to  the  ultimate  market, 
thereby  saving  the  expense  of  shipping  the  coal  and  the 
possibility  of  shortage  of  coal  caused  by  labor  troubles 
on  the  railroad. 

In  general,  the  location  of  a  power  plant  at  a 
mine  will  insure  freedom  from  the  effects  of  a  coal 
strike  or  a  railroad  strike.  In  the  case  of  abnormal 
conditions,  such  as  the  recent  war  period,  it  will  re- 
sult in  securing  a  uniform  grade  of  coal  at  a  reasona- 
ble cost. 


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FIG.    I —  TRANSMISSION   COSTS  FOR  SO  PERCENT  USE  FACTOR 

In  considering  the  location  of  a  plant  at  a  mine,  in 
addition  to  the  fuel  supply,  an  even  more  vital  con- 
sideration is  whether  adequate  water  is  available  for 
condensing  purposes.  A  modem  steam  turbine  plant 
requires  about  1.5  gallons  or  0.2  cu.  ft.  per  minute 
per  kilowatt  of  station  capacity,  and  in  the  coal  areas, 
with  the  exception  of  the  Pittsburgh  district,  there  are 
few  sites  where  the  amount  of  water  is  sufficient  for 
plants  .of  100  000  kw  and  larger. 

Real  estate  near  a  mine  can  generally  be  secured 
at  a  lower  cost  than  in  a  large  city,  and  the  power  plant 
structure  can  usually  be  less  pretentious  from  the 
architectural  standpoint.  Tht  main  question,  how- 
ever, is  whether  the  cost  of  transmitting  electrical 
energy  is  less  than  the  cost  of  the  rail  shipment  of  coal. 
The  cost  of  transmitting  electrical  energy  depends  on 
many  factors,  such  as  the  amount  of  power  trans- 
mitted, the  load  factor,  and  the  amount  of  spare  equip- 
ment provided  for  emergency  use.  The  latter  factor 
will  be  based  on  the  attitude  of  the  operating  com-j 
panies  towards  continuity  of  service,  the  type  of  coun- 


trj-  traversed  by  the  transmission  lines  and  the  charac- 
ter of  the  load  served. 

Transmission  lines  may  have  interruptions  due  to 
broken  insulators,  lightning,  high  winds  and  storms, 
and  to  guard  against  these  failures  requires  additional 
transmission  circuits  or  else  standby  generating  sta- 
tions at  the  load  end  of  the  line.  A  recent  A.  I.  E.  E. 
paper*  discusses  the  service  that  can  be  expected  from 
long  distance  transmission  lines  and  arrives  at  the  con- 
clusion that  "two  tower  lines,  each  supporting  two  cir- 
cuits, each  tower  line  with  its  circuits  being  capable 
in  emergency  of  transmitting  the  entire  load,  would 
reasonably  insure  continuity  of  service  of  the  charac- 
ter demanded  by  the  metropolitan  district  of  New 
York  City." 

To  determine  the  cost  of  electric  transmission,  a 
large  number  of  items  have  to  be  considered,  many  of 


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X 

Jo.13 
—0.11 
—0.10 

^ 

\ 

^ 

^ 

y 

/ 

1 

"^ 

^ 

^' 

1 

r 

^ 



_^ 

■0^ 

' 

9 

Tboiu 

1 

and  I 

;wi> 

r 

pw 

3 
rowe 

u 

Line 

T 

T 

FIG.  2 — ^TRANSMISSION  COSTS  FOR   100  PERCENT  USE  FACTOR 

which  will  depend  on  local  conditions,  so  that  this  arti- 
cle will  indicate  only  in  general  terms  the  method  to 
be  followed. 

In  calculating  the  transmission  cost,  the  following 
formula  has  been  used.  The  transmission  cost  per 
kilowatt-hour  delivered  = 

A-VB-^C-\-D-\-E-^F-\-G 
A'<v  Ilr.  delivered 
Where  ^  =  The  fixed  charges  on  the  step-up  transformer  sub- 
station, 
B  =  The  fixed  charges  on  the  transmission  hnes, 
C==The  fixed  charges  on  the  step-down  transformer  sta- 
tions, . 
D  =  The    fixed    charges    on    the    synchronous  condensers 
necessary,    together    with    switching    equipment    and 
transformers. 
£  =  The  fixed  charges  on  the  additional  generatmg  capa- 
city to  compensate  for  the  losses, 
ft^The  cost  of   the  yearly  losses   in   transmission  lines, 

substations,  and  condensers, 
(J=  The  yearly  operating  cost  of   substations  and  trans- 
mission lines.  _ 
There   are   various   details   connected   with   these 

items  which  should  be  further  discussed. 


*"Long-Distance  Transmission  of  Electric  Energy"  by  L. 
E.  Imlay,  in  the  Journal  a.  i.  e.  e.,  June  1921,  P-  5i6- 


September,  1921 


THE   ELECTRIC   JOURNAL 


403 


If  a  plant  is  built  at  the  load  center,  the  extent  of 
the  distribution  network  may  be  such  that  it  cannot  be 
served  at  the  generator  voltage,  and  so  a  step-up  trans- 
former substation  is  necessary  with  various  outgoing 
feeders.  The  cost  of  this  substation  could  be  ver}' 
properly  deducted  from  the  main  step-down  substation 
in  the  transmission  scheme. 

TABLE    1—220    k'  V    TRANSMISSION 


Receiver  load 
in  k  w. 

.00000 

150000 

2C«000 

250000 

3CX>ooo 

Condenser  Capacity 
for   100%    P..F.    re- 
ceiver load  to  Main- 
tain   receiver    volt- 
tage  200000. 

'uT 

iSooo 
lag 

... 

18000 

""" 

Condenser   capacity 
with     Ss%     receiver 
P.  F.  to  maintain  re- 
ceiver voltage  200000 

5S000 

87000 

144000 

191000 

256000 

Condenser  losses 
in  k  w. 

■800 

2400 

3600 

5400 

-200 

Line  losses 
in  k  w. 

156S 

345S 

5S0O 

9028 

13372 

Transformer  losses 
in  k  w. 

296S 

4572 

5172 

-340 

S640 

Total  losses 

S3.* 

.0370 

15472 

21760 

29200 

Efficiency  percent 

94 

«3-5 

92,8 

92 

9. 

Generator 
l)0\ver-laclor  percent 

<19-5 

9Q.,S 

97.3 

97.3 

96.6 

On  transmission  lines,  it  is  now  customary  to  pro- 
vide sufficient  synchronous  condenser  capacity  to 
maintain  a  constant  receiver  voltage.  The  capacity 
required  is  generally  in  excess  of  that  necessary  to 
in  the  receiver  distributing  network,  if  the  synchron- 
that  the  power-factor  is  corrected  to  unity  will  result 
in  better  voltage  regulation  and  reduced  copper  losses 
in  the  receiver  distributing  network,  if  the  synchron- 
ous condensers  are  located  at  various  points  on  the  re- 

TABLE    11.-154    K  V    TRANSMISSION 


Receiver  Load 
in  k  w. 

100  000 

150000 

200000 

250 

000 

300000 

Condenser  capacity 
power  factor 

6000 

14000 

32000 

80 

000 

,46000 

Condenser  capacity 
with    85%    recei%er 
power-factor. 

74000 

1 19  000 

16S000 

253 

000 

350000 

Condenser 
losses 

1800 

3600 

5400 

7 

200 

10800 

Line  losses 

3200 

6640 

12400 

20 

520 

.i4  740 

Transformer 
losses 

2620 

4094 

5740 

7 

400 

8600 

Total  losses 

7620 

14  334 

23540 

35520 

54  140 

Efficiency,  percent. 

92-9 

91-3 

89.5 

87.5 

S4.7 

Generator  power- 
factor,  percent. 

94-8 

95.8 

95-5 

93.5 

91.5 

ceiver  network.  If,  however,  the  condensers  are  lo- 
cated in  the  main  step-down  substation,  all  the  losses 
incident  to  a  lagging  power-factor  are  still  present 
in  the  receiver  network.  It  may,  therefore,  be  argued 
that,  in  the  former  case,  all  synchronous  condenser 
capacity  should  not  be  charged  against  the  transmis- 
sion scheme  or,  expressed  in  another  way,  the  trans- 


mission scheme  should  be  credited  with  whatever  re- 
duction of  losses  and  increased  kilowatt  capacity  is 
gained  in  the  receiver  network  due  to  the  use  of  syn- 
chronous condensers. 

The  losses  in  transformers,  condensers  and  trans- 
mission lines  will  var>'  with  the  load,  so  that  in  order  to 
calculate  the  yearly  losses,  it  is  necessary  to  know  the 
load  and  the  time  interval  that  the  load  is  on.  As 
the  load  factor  does  not  give  this  data  without  the  ad- 
dition of  a  load  curve,  it  is  advisable  to  use  some  other 
factor  for  general  calculations.  A  convenient  expres- 
sion is  the  term  "use-factor"  which  can  be  defined  as 
follows:  For  any  given  demand,  a  50  percent  use- 
factor  means  the  use  of  this  demand  for  50  percent  of 
the  time,  and  the  losses  are  taken  as  corresponding  to 
the  loss  at  this  demand  for  half  the  time.  Fixed 
charges  may  be  taken  as  follows: — 

Transmission   lines    12   percent 

Power  stations  and  substations 14  percent 

Standard  voltages  for  transmission  purposes  are 
1 10  000,  132000,  154000,  and  220000  volts.  These 
voltages  are  the  voltages  at  the  generating  station  end 


FIG.    T. — COSTS   PER   KW-HR  FOR  SHIPPING  CO.\L   BY   FREIGHT 

and   the   voltages   at   the   receiver   end   are   commonly 
taken  as  100  000,  120000,  140000  and  200000. 

The  procedure  to  be  followed  in  making  a  detail 
study  of  the  cost  of  transmission  is  as  follows : 

I — Calculate  the  performance  of  the  transmission  line 
and  determine  the  necessary  condenser  capacity  required 
to  transmit  the  load. 

2 — For  various  loads,  calculate  the  losses  in  trans- 
mission lines,  transformers  and  synchronous  condensers. 

3 — Estimate  the  cost  of  substations,  transmission  lines, 
synchronous  condenser  and  the  additional  generating 
plant  to  supply  the  losses. 

4 — Determine  the  fixed  charges,  the  cost  of  yearly 
losses,  cost  of  operation,  and  tabulate  the  information  for 
various  demands  and  use- factors. 

5 — Calculate  by  the  formula  the  cost  of  transmission 
per  kw-hour  delivered. 
As  an  example  typical  of  the  general  method,  con- 
sider a  double  circuit  tower  line,  90  miles  long,  with 
conductors  of  500000  circ.  mil  copper.  Tables  I  to 
IV  give  the  performance  of  this  line  for  the  different 
voltages,  and  the  curves  in  Figs,  i  and  2  show  the  cost 
of  transmission  in  cents  per  kw-hr.  for  use  factors  of 
50  and  100  percent.  A  spare  double  circuit  trans- 
mission line  has  been  included  to  secure  a  high  degree 
of   service.     The   costs   of   lines   and   substations   are 


404 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


based  on  present  day  costs  and  include  all  equipment 
necessary-,  real  estate,  buildings  and  erection  of  all 
equipment.  A  spare  transformer  has  been  included 
in  each  substation,  also  spare  parts  for  switches,  and 
a  set  of  coils  for  synchronous  condensers.  The  oper- 
ating costs  have  been  based  on  the  results  obtained 
from  modern  transmission  systems.  In  determining 
the  cost  of  the  yearly  losses,  the  price  of  a  kilowatt- 
hour  has  been  assumed  to  be  0.5  cent  per  kw-hour. 
Tables  I  to  IV  are  based  on  two  circuits  of  a  double 
circuit  tower  line.  The  spare  double  circuit  towci 
line  has  been  assumed  not  to  carry  any  load  in  calcu- 
lating the  performance  given  in  the  tables,  though  un- 
der actual  conditions  all  four  circuits  would  be  used 
to  carry  load.  In  Figs,  i  and  2,  the  demand  includes 
the  two  circuits  of  one  tower  line. 

In  basing  any  conclusions  on  die  results  shown  in 

TABLE    HI.— 132    K  \'    TRANSMISSION 


Receh  ei-  load 
in  k  w. 

50000 

100  000 

150000 

200000 

250000 

Condenser  capacity 
loojS  receiver  power- 
factor. 

8000 
lag 

.0000 

36000 

84000 

116000 

Condenser  capacity 
S5JS  receiver  power- 
factor. 

26000 

78  000 

144000 

220000 

28.>ooo 

Condenser 
loss 

730 

2400 

3600 

5400 

:20a 

Line 
losses 

1036 

4000 

9680 

iS^joo 

30200 

Transformer 
losses 

1492 

2.S70 

37ao 

52'<o 

6720 

Total 
losses 

325S 

S970 

.7000 

29580 

4412c 

Efficiency,  per  cent. 

940 

92.2 

89.S 

S-.I 

S5.0 

Generator  power- 
factor,    percent. 

93- 

9»-5 

9.V5 

95-3 

91.2 

Figs.  I  and  2,  it  should  be  remembered  that  they  show 
the  solution  of  a  particular  problem  and  the  same  si.'ie 
conductor  has  been  used  for  all  four  voltages.  The 
curves  clearly  illustrate  that  for  minimum  transmis- 
sion cost,  the  larger  the  block  of  power  to  be  trans- 
mitted the  higher  the  transmission  voltage. 

Fig.  3  shows  the  cost  of  rail  shipment  for  varying 
freight  rates  and  fuel  economies.  Modern  stations 
have  operating  records  from  1.4  to  1.6  pounds  of  coal 
per  kw-hour  based  on  coal  of  calorific  value  of  13  500 
B.t.u.  per  pound. 

As  will  be  seen  from  the  curves,  the  cost  of  trans- 
mission depends  largely  on  the  use  factor.  At  50  per- 
cent use  factor,  for  demands  per  tower  line  vaiying 
from  80000  to  300000  kw,  the  cost  of  transmission 


will  only  vary  from  0.22  to  0.18  cent  per  kw-hr.  and 
for  100  percent  use  factor  from  0.14  to  0.12  cent. 
With  a  modern  plant  burning  1.5  lbs.  of  coal  per  kw- 
hr.  and  $2.00  per  ton  freight  rate,  the  cost  of  rail  ship- 
ment is  0.15  cent  per  kw-hr. 

If  the  mouth  of  mine  plant  and  transmission  sys- 
tem is  built  as  an  addition  to  an  existing  plant  to  meet 
the  increased  demands,  it  may  be  possible  to  operate 
the  modern  plant  and  the  transmission  system  at  a  high 
use  factor,  holding  the  local  plant  for  peak  loads  and 
emergency  conditions.  This  is  especially  true  when  a 
number  of  plants  are  interconnected  and  are  available 
for  service  in  case  of  emergenc\\  Actual  operating 
records  show  that  large  turbine  units,  condensers, 
transformers  and  transmission  lines  can  be  oi)erated 
for  long  periods  at  full  load,  and  thus  maximum  re- 
turns can  be  gained  from  the  investment. 

TABLE    IV.— 110    K  V    TRANS.MISSION 


Receiver  load 
in  k  w. 

50000 

100  000 

150000 

200000 

Condenser  capacity 
looJS  receiver 
power-lactor. 

° 

20000 

50000 

132000 

Condenser  capacity 
S5X    receiver 
power-lactor. 

34000 

88  000 

155  000 

268000 

Condenser 
lo-sses 

S40 

2600 

3600 

7200 

Line 
losses 

1.164 

6020 

14360 

32.960 

Transformer 
losses 

1360 

2340 

3632 

4900 

Total 
losses 

3.S^ 

1oq6o 

21600 

45060 

Efficiency  perce::i 

93-4 

>)O.I 

87.4 

81.6 

Generator 
power-faclor  percent 

98.5 

•  97- 

94  ..S 

90.9 

Under  these  conditions,  the  cost  of  transmission 
is  low  which  combined  with  the  indirect  advantages 
mentioned  earlier,  makes  the  transmission  scheme  ver}' 
attractive.  As  a  further  advantage  to  the  country  at 
large,  a  large  number  of  railroad  cars  and  their  at- 
tendant train  crews  would  be  released  for  other  serv- 
ice. 

In  the  Pittsburgh  district,  there  are  large  coal  de- 
posits along  the  rivers,  so  that  both  coal  and  water  are 
available  in  almost  unlimited  quantities.  Away  from 
the  main  rivers,  however,  water  is  not  available  for 
large  plants,  so  that  extensive  transmission  systems 
are  developing,  supplying  large  amounts  of  cheap  pow- 
er to  cities  where  the  water  conditions  do  not  permit 
the  building  of  large  plants. 


Insulation  for  Stool  Mill  Moiors 


IN  addition  to  demanding  more  from  a  motor  in 
rolling  mill  service  than  is  expected  in  the 
average  application,  the  rolling  mill  presents  ex- 
ceptionally severe  operating  conditions.  The  windings 
become  covered  with  mill  dust  which  is  more  or  less 
conducting.  This  dust  tends  to  work  into  the  small 
crevices  to  such  an  extent  as  to  puncture  the  insulation. 
Many  of  the  motors  are  subject  to  vibration  from  the 
load  which  they  drive.  The  vibration  chafes  the 
insulation  and  accelerates  failures  caused  by  dust  or 
by  temperatures  above  the  safe  limit.  The  motors 
may  even  be  subject  to  salt  scale  and  moisture  which 
becomes  chemically  active  and  injurious  to  the  insu- 
lation. The  motors  which  operate  over  the  furnaces 
or  near  them  are  frequently  as  hot  at  no  load  as  an 
ordinary  motor  is  supposed  to  be  at  full  load.  Thus 
these  motors  require  insulation  which  will  safely 
stand  very  high  temperatures. 

The  insulation  which  successfully  withstands  the 
severe  operating  conditions  and  fully  meets  the  re- 
quirements and  expectations  must  be  of  the  best.  It 
must  not  only  be  good  when  it  is  new,  but  must  have 
life  that  will  preserve  it  through  severe  operating  con- 
ditions. This  requires  high  grade,  materials,  their  cor- 
rect combination  and  grouping,  adequate  methods  of 
applying  and  of  protecting  them.  Not  only  must  the 
insulation  conform  to  the  electrical  and  mechanical 
features  of  the  design,  but  the  electrical  and  the  me- 
chanical features  must  be  made  to  conform  to  the  re- 
quirements of  good  insulation. 

Insulation  may  be  likened  to  the  arteries  and  veins 
of  the  human  body  through  which  the  life  blood  is  car- 
ried to  all  parts  of  the  body.  In  like  manner  the  insula- 
tion directs  the  path  of  the  electric  current  through  the 
proper  circuits.  The  protection  which  the  insulation 
must  offer  can  be  divided  into  three  classes. 

I — To  protect  against  a  short-circuit  between  adja- 
cent turns  or  other  parts  of  the  same  coil;  that  is,  on  the 
inside  of  the  coil. 

2 — To  protect  against  the  ground  strain  in  the  slots 
or  other  parts  iu  contact  with  the  core.  There  is  a  con- 
tinuous dielectric  strain  from  the  winding  to  ground. 

3 — To  protect  one  circuit  from  another  between  which 
there  is  possibly  full  rated  voltage,  such  as  from  one 
phase  to  another  on  polyphase  alternating-current  motors 
and  from  the  positive  side  of  the  circuit  to  the  negative 
side  on  direct-current  circuits. 

INSULATION   ON   STATOR   WINDINGS   OF  LARGE  ALTERNAT- 
ING CURRENT  MILL  MOTORS 

The  following  methods  of  insulating  to  protect 
against  short-circuits  within  a  coil  represent  the  best 
modern  practice.  On  induction  motors  for  rolling 
mills  the  stator  winding  is  composed  of  diamond 
shaped  coils.  The  cenductors  are  rectangular  shaped 
and  cotton  covered.  The  coil  is  made  to  the  correct 
shape  so  that  it  will  fit  into  the  slots,  and  so  that  the 


J.  L.  RYLANDEK 

Insulation  Engineer, 
Westinghouse  Electric  &  Mfg.  Company 

voltage  of  one  turn  of  wire  is  the  maximum  voltage 
between  any  two  wires  lying  side  by  side  in  the  coil. 
This  makes  the  dielectric  strain  on  the  insulation  in- 
side of  the  coil  a  minimum.  The  rectangular  conduc- 
tors keep  the  mechanical  strain  of  the  wires  resting  or 
pressing  against  the  adjoining  wires  to  a  minimum 
value  by  having  a  flat  surface  resting  against  a  flat  sur- 
face. 


The  coil  is  then  treated  in  a  compound  which 
causes  each  cotton-covered  conductor  to  be  completely 
surrotmded  with  a  homogeneous  compound,  of  hign 
dielectric  strength,  that  resists  moisture  and  high  tem- 
perature and  thereby  adds  greatly  to  the  life  and  safe- 
ty of  the  insulation.  On  the  larger  motors  this  is  done 
by  placing  them  in  an  impregnating  tank.  The  coils 
are  dried  by  raising  the  temperature  in  the  tank  and 
then  creating  a  vacuum  to  remove  the  last  traces  of 
moisture  and  to  cause  the  cotton  covering  on  the  wires 
to  absorb  the  compound  readily.  The  compound  is 
then  forced  into  the  tank  and  into  the  coils  under  hy- 
draulic pressure. 

The  insulation  on  the  slot  portion  of  the  coil  must 
be  the  best  possible,  as  it  must  stand  the  full  dielectric 
strain  to  ground  and  also  resist  the  mechanical  and 
electrical  strains.  On  a  three-phase  circuit,  this 
strain  is  equal  to  the  voltage  between  terminals  divided 
by  1-73,  if  no  part  of  the  winding  is  grounded.  If  one 
side  of  the  line  circuit  becomes  grounded,  the  strain 
on  the  slot  insulation  of  each  coil  becomes  equal  to  the 
terminal  voltage.  This  insulation  must  have  high 
dielectric  strength  to  withstand  the  ground  strain  and 
must  have  small  dielectric  loss.  It  must  have  suffi- 
cient mechanical  strength  to  stand  the  twisting  of  plac- 
ing the  last  throw  of  coils  into  the  slots  when  winding, 
and  to  resist  the  strains  due  to  vibration,  accidents  and 
short-circtiits. 

The  slot  portion  is  insulated  with  a  wrapper  which 
is  a  combination  of  materials  that  will  best  serve  this 
purpose.  This  wrapper  is  usually  composed  of  a  number 
of  layers  of  mica  splittings  which  are  built  up  with  a 
special  mica  bond  for  sticking  them  together  and  on  a 
high  grade  paper.  Mica  is  the  best  insulation  known. 
It  has  a  high  dielectric  strength.  It  is  the  best  for  re- 
sisting high  temperature.  Its  resistance  to  crushing 
is  very  high.  It  is  the  best  material  for  resisting  mois- 
ture as  it  is  practically  non-absorbent.  It  is  resilient 
and  therefore  acts  as  a  spring  in  keeping  coils  tight 
in  the  slot  to  take  up  any  shrinkage  in  the  other  ma- 
terials. The  paper  acts  as  the  backing  for  the  built 
up  mica  and  furnishes  the  required  toughness  as  well 
as  increased  dielectric  strength.  The  paper  is  chosen 
on  the  basis  of  toughness  and  dielectric  strength. 


4o6 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


The  end  portions  of  the  coil  especially  are  subject 
to  the  action  of  the  gritty  mill  dust  and  moisture,  and 
to  any  vibration  that  may  exist.  The  ends  are  there- 
fore insulated  in  such  a  way  as  to  provide  maximum 
insurance  against  short-circuits  within  the  coil  and 
from  coil  to  coil  and  between  phases  under  the  above 
conditions.  The  thorough  impregnation  of  the  con- 
ductors in  the  coil  protects  them  one  from  another. 
The  taping  of  the  end  portions  of  the  coil  with  layers 
of  a  high-grade  treated  tape  followed  by  a  layer  of  cot- 
ton tape  which  is  later  thoroughly  filled  with  varnish, 
effectively  furnishes  the  necessary  protection.  Each 
layer  of  tape  is  half  overlapped.  Each  layer  of  treated 
tape  is  thoroughly  brushed  with  a  good  insulating 
varnish  which  makes  the  insulation  more  compact  as 
well  as  improves  the  dielectric  strength  and  seals 
against  dust  penetration.  The  treated  tape  has  very 
high  dielectric  strength  and  is  the  best  material  for  in- 
sulating the  end  portions. 

The  outside  of  the  coil  is  completely  taped  with 
a  layer  of  cotton  tape  which  is  half  overlapped  on  the 
end  portions  and  has  the  edges  butted  over  the  slot 
portion.     This  tape  has  several  functions  to  perform. 


FIG.    I — A   TYPICAL   ROTOR  COH-   FORMED  TO  EXACT   SHAPE    AND  COM- 
Pl-ETELY   INSULATED  BEFORE   PLAONG    IN    SLOT 

It  holds  firmly  in  place  the  main  insulation  which  is 
depended  upon  for  the  dielectric  strength  and  also 
protects  this  insulation  from  mechanical  damage.  It 
is  then  given  thorough  varnish  treatments  for  further 
protection  against  moisture  and  gritty  dust.  These 
varnish  treatments  add  to  the  dielectric  strength  and 
increase  the  life  of  the  tape,  and  also  facilitate  the  con- 
duction of  heat  from  the  coils.  They  include  drying, 
dipping,  draining  and  baking,  these  operations  being  re- 
peated until  the  required  number  of  coats  have  been 
applied. 

Before  placing  the  coils,  tlie  slots  are  smoothed  off 
by  filing  so  as  to  remove  any  burrs  or  rough  spots. 
Slot  cells  are  then  placed  in  the  slots  so  as  to  add  ad- 
ditional mechanical  protection  for  the  insulation  on 
the  coils.  A  very  tough  paper  is  used  for  this  pur- 
pose so  that  the  laminations  will  not  cut  their  way  into 
the  coil  insulation  when  the  winding  is  subjected  to 
mechanical  stresses.  As  this  paper  cell  serves  the 
same  purpose  while  inserting  the  coils  into  the  slots, 
it  is  dipped  in  paraffine  to  further  facilitate  this  pro- 
cess. 

The  connections  from  one  coil  to  another  and 
from  one  group  of  coils  to  the  others  are  usually  insu- 
lated by  taping  with  layers  of  treated  tape  and  cotton 


tape  as  used  on  the  ends  of  the  coils.  In  other  cases, 
heavy  rubber  insulated  cables  are  used.  These  con- 
nections must  be  roped  together  and  be  well  braced. 

The  individual  conductors  in  a  coil  can  readily  be 
protected  from  each  other  so  as  not  to  chafe  if  the  mo- 
tor is  subject  to  vibration.  However,  the  coil  ends 
must  be  securely  braced  so  there  is  no  chafing  of  the 
outside  coil  insulation.  Each  coil  is  therefore  secure- 
ly roped  to  an  insulated  welded  steel  supporting  ring," 
which  is  braced  by  arms  fastened  to  the  end  plates  so 
as  to  brace  the  whole  winding  as  a  unit. 

After  winding  all  coils  into  the  slots  and  complet- 
ing all  of  the  connections,  two  or  more  coats  of  a  good 
baking  varnish  are  applied  to  the  complete  winding. 
This  fills  up  the  insulation  on  the  connections  and  seals 
up  the  very  small  crevices  between  coils  into  which 
gritty  dust  or  moisture  might  accumulate.  It  adds 
further  strength  mechanically  and  dielectrically.  Rec- 
cords  show  that  varnish  dipping  of  complete  windings 
may  more  than  double  the  life  of  the  windings. 


FIG.  B — SECTION   THROUGH   ROTOR  COn,  AND  SLOT 

ROTOR  WINDINGS  OF  LARGE  ALTERNATING-CURRENT  MILL 
MOTORS 

It  is  desirable  from  the  standpoint  of  performance 
of  the  motor  to  use  partially  closed  slot  construction 
on  the  rotor.  It  is  also  very  desirable  to  have  coils 
which  are  completely  formed  to  shape  and  completely 
insulated  before  placing  them  in  the  slots.  Such  coils 
make  winding,  rewinding  or  repairing  quite  simple. 
That  is,  all  of  the  advantages  of  an  open  slot  fonned 
coil  are  wanted  for  a  slot  which  is  made  partially 
closed  or  with  an  over-hung  tip  for  its  great  electri- 
cal advantages. 

This  is  accomplished  by  the  type  of  coil  shown  in 
Figs.  I  and  2,  and  by  the  type  of  slot  shown  in  Fig.  2. 
Each  coil  is  divided  into  two  units  side  by  side,  each 
of  which  is  completely  insulated  to  stand  the  total  die- 
lectrical  strains,  and  the  slot  opening  is  made  sufficient- 
ly large  for  one  unit.  The  slot  portions  of  each  of  these 
rotor  coil  straps  are  insulated  with  the  same  high-grade 
paper  and  mica  wrapper  that  is  ustd  on  the  stator  coils. 
The  end  portion  of  each  strap  is  taped  with  layers  of 
treated  tape  cut  on  the  bias.     A  layer  of  cotton  tape 


September,  1921 


THE   ELECTRIC  JOURNAL 


407 


is  taped  over  the  outside  of  each  strap,  the  tape  being 
half  overlapped  on  the  end  portions  and  the  edges 
butted  on  the  slot  portion.  The  coils  are  then  given 
a  number  of  thorough  treatments  of  varnish  to  protect 
against  moisture  and  gritty  dust.  Each  treatment  in 
varnish  always  includes  drying,  dipping,  draining  and 
baking.  The  drying  is  done  at  a  temperature  slightly 
above  the  boiling  point  of  water  to  drive  out  the 
moisture  and  so  that  the  varnish  will  be  thoroughly  ab- 
sorbed. The  dipping  is  done  while  the  coil  is  hot. 
The  baking  is  continued  until  the  varnish  is  thorough- 
ly baked.  The  slots  are  filed  so  as  to  remove  any  burrs 
or  rough  spots.  Tough  paper  cells  are  placed  into 
the  slots  which  protect  the  coil  insulation  from  the 
laminations. 

The  connections  on  the  end  windings  from  coil  to 
coil  and  from  one  group  to  another,  of  a  rotor  winding 
requires  careful  attention.  On  account  of  their  shape, 
tape  alone  is  not  sufficient.  Therefore,  caps  are  sewed 
from  heavy  cotton  cloth  into  a  shape  that  fits  snugiy 
over  each  connector.  Each  cap  is  then  dipped  in 
varnish,  drained  and  dried  in  a  heater  until  it  has  re- 
ceived three  coats.  A  number  of  caps  are  used  over 
each  connector.  After  putting  each  cap  in  place,  it  is 
held  by  tape  in  such  a  manner  that  conducting  dust 
cannot  enter  and  form  a  path  from  one  connector  to 
another.  Treated  tape  is  used  for  tapping  over  the 
caps  on  all  except  the  outside  one  on  which  cotton  tape 
is  applied.  This  layer  of  cotton  tape  and  the  complete 
insulation  joint  is  thoroughly  filled  with  varnish  when 
the  completed  winding  is  given  two  varnish  treatments. 

The  bracing  of  the  rotor  winding  and  connections 
is  very  important  because  there  must  not  be  the  slight- 
est movement  of  any  part  that  would  eventually  chafe 
through  the  insulation.  The  gritty  dust  greatly  accel- 
erates the  effect  of  chafing.  Strong,  well  insulatated 
coil  supports  are  therefore  used  under  both  ends  of 
the  windings.  The  bottom  layer  of  the  winding  rests 
firmly  on  the  supports.  The  top  layer  of  the  winding 
is  separated  from  the  bottom  winding  by  heavy  treated 
duck  and  presses  down  firmly  on  it.  A  substantial 
steel  band  well  insulated  from  the  coils  is  placed  over 
them.  The  complete  winding  is  thereby  securely 
clamped  between  the  coil  supports  and  the  banding 
wire.  The  leads  and  connections  are  held  tightly  in 
cleats  at  which  places  the  insulation  is  further  pro- 
tected by  additional  insulation  to  withstand  the  tight 
clamping. 

After  winding  all  coils  into  the  slots  and  com- 
pleting all  of  the  connections  and  banding,  two  coats  of 
a  good  baking  varnish  are  applied  to  the  complete  ro- 
tor winding  the  same  as  is  done  to  the  stator  winding. 
This  adds  to  the  desired  rigidity  of  the  winding  as  well 
as  filling  up  all  crevices  to  protect  against  the  moisture 
and  the  gritty  dust,  and  thereby  adds  greatly  to  the  life 
of  the  winding. 


MILL    MOTOR    ARMATURES    FOR   VERY    HIGH    OPERATING 
TEMPERATURES 

In  some  motor  applications  the  motors  operate 
where  the  temperature  is  high.  They  may  be  hot  with- 
out any  rise  in  temperature  in  the  windings  themselves. 
When  operating  at  the  average  load  the  temperature 
of  the  windings  are  therefore  much  higher  than  is  safe 
for  the  ordinary  insulation  known  as  Class  A  in  the 
rules  of  the  American  Institute  of  Electrical  Engineers. 
Class  A  insulation  allows  a  hot  spot  temperature  in  the 
windings  not  to  exceed  105  degrees  C. 

These  very  high  temperatures  would  disintegrate 
the  ordinary  organic  insulating  materials  such  as 
papers,  cotton  and  other  fibrous  materials  used  in  Class 
A  insulation.  Temperatures  above  105  degrees  C 
cause  the  organic  materials  to  shrink  and  become  brit- 
tle and  the  materials  will  eventually  carbonize  if  the 
temperature  is  sufficiently  high.  If  the  insulation  be- 
comes brittle  it  will  probably  fail  mechanically  by 
cracking  open  when  the  armature  is  subject  to  a  severe 
mechanical  strain,  such  as  a  quick  start  or  a  quick  stop, 
or  some  jarring  action.  If  the  insulation  shrinks  so 
as  to  allow  a  movement  of  the  coils,  only  a  small 
amount  of  brittleness  is  required  to  crack  the  insula- 
tion. It  is,  therefore,  not  necessary  that  the  material 
carbonize  to  cause  failure.  High  dielectric  strength 
alone  is  not  a  protection  in  such  cases.  The  insulation 
requirements  of  the  armatures  are  very  severe  because 
the  effects  of  the  rapidly  changing  centrifugal  speeds 
are  added  to  the  vibration  and  jolts  due  to  the  particu- 
lar application. 

The  insulation  used  for  these  applications  is  com- 
posed of  mica  and  asbestos  with  the  minimum  amount 
of  cotton  and  fibrous  paper  materials  used  as  binders 
or  supporting  structures.  If  the  conductors  are  small 
or  medium  size,  they  have  a  covering  of  asbestos. 
The  larger  size  conductors  are  insulated  with  mica  ap- 
plied in  the  form  of  tape.  A  paper  and  mica  wrapper 
is  used  for  insulating  the  slot  portion  of  the  armature 
coils.  A  layer  of  asbestos  tape  is  capped  over  the  out- 
side of  the  complete  armature  coil. 

The  method  of  making  the  coils  and  winding  them 
into  the  slots  has  much  to  do  with  the  successful  opera- 
tion and  life  of  the  insulation.  That  is,  all  parts  of 
the  coils  and  windings  must  be  compact.  Even  with 
the  best  quality  of  insulation  and  regardless  of  the 
quantity,  the  winding  mtist  have  this  compactness,  as 
otherwise  the  coil  would  soon  become  loose  in  the  slot 
or  on  the  ends. 

The  method  of  making  coils  for  this  service  is  to 
hot  press  the  coil  before  applying  the  insulation  and 
then  hot  press  them  again  after  applying  the  insulation. 
If  there  is  space  for  a  filler,  mica  or  micarta  plate 
which  stands  a  high  temperature  is  used.  By  these 
methods  there  will  be  no  small  air  pocket  to  be  crushed 
out  in  service  or  any  excess  material  to  carbonize  that 
might  cause  looseness  which  would  be  followed  by  fail- 
ure. 


4o8 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


FIELD  COILS  FOR   HIGH  TEMPERATURE  OPERATIONS 

The  field  coils  of  direct-current  mill  motors,  al- 
though stationary  are  subject  to  considerable  vibration 
and  mechanical  stresses.  The  strains  occurring  on 
motors  operating  at  temperatures  of  125  degrees  C. 
are  too  severe  for  the  ordinary  fibrous  materials.  If 
the  conductors  are  small,  asbestos  insulated  conductors 
are  used.  If  the  conductors  are  medium  or  large  size, 
strips  of  sheet  asbestos  are  used  as  a  separating  med- 
ium, with  the  bends  specially  reinforced.  The  places 
where  the  leads  leave  the  coil  or  cross  the  coil  are  also 
specially  reinforced.  The  coils  are  next  given  a 
thorough  treatment  in  an  insulating  compound  after 
drying.  The  coils  are  then  insulated  by  applying  a 
heavy  insulation  composed  of  cloth  and  mica,  and 
paper  and  mica,  with  the  minimum  amount  of  the 
fibrous  materials.  The  fact  that  mica  is  practically 
incompressible  and  retains  its  high  dielectric  strength 
even  at  high  temperatures  makes  it  a  valuable  insula- 
tion for  this  application.  Each  coil  is  taped  overall 
with  a  layer  of  heavy  asbestos  tape  whose  mechanical 
strength  is  practically  unaffected  at  temperatures  of 
several  hundred  degrees  C.     The  insulated  coil  is  then 


thoroughly  treated  in  varnish. 

MILL   MOTOR  COMMUTATORS 

In  direct-current  machines,  the  commutators  are 
regarded  as  tlie  part  most  susceptible  to  trouble.  Only 
the  best  insulation  can  be  considered  for  the  mill  motor 
commutators  because  a  failure  usually  causes  great  in- 
convenience, delay  and  expense.  A  failure  in  the 
commutator  may  also  be  the  cause  of  short-circuits  in 
the  winding  which  may  necessitate  the  rewinding  of 
the  complete  armature. 

Amber  mica  is  used  between  the  bars,  and  the 
V-rings  are  made  of  moulded  white  mica.  Mica  is 
the  only  satisfactory  insulation  for  these  items.  The 
portions  of  the  V-rings  which  project  beyond  the  bars 
sre  protected  with  tape,  thoroughly  filled  with  coats 
of  thin  varnish.  This  makes  a  surface  which  is  easy 
to  keep  free  from  the  conducting  dust. 

INSULATION  TESTS  FOR  ALL  MOTORS 

The  last  operation  on  the  motors  before  they  are 
ready  for  service  is  an  insulation  test  applied  between 
the  windings  and  frame  for  one  minute  with  a  voltage 
equal  to  twice  the  terminal  voltage  plus  1000  or  greater. 


.lloc|i(dnr 


iVlocluuiioa 


M 


'  ANY  of   the   difficulties   encountered   in   motor 
applications  are  mechanical  and  not  electrical. 
Motors  as  applied  to  various  drives  may  be 
classified    under    four    divisions,    depending    upon    the 
method  of  driving  the  load: — 
I— Belted 
2 — Geared 
3 — Chain  driven 
4 — Direct  connected 
A  further  classification  may  be  made  according  to 

the  character  of  the  load  under  two  heads : — 
I — Cushioned  loads 
2 — Uncushioned  loads 
A  "cushioned"  load  is  such  as  a  radial  blower  fan, 

where  the  elastic  characteristics  of  the  air  do  not  offer 
any  forced  shocks  or  impacts  to  the  driving  motor. 
Where  shocks  or  impacts  are  encountered  as  in  driving 
ore  crushers  or  punching  machines,  the  load  is  said  to 
be  "uncushioned." 

In  the  design  of  machines  to  meet  certain  require- 
ments, the  parts  are  proportioned  to  meet  the  known 
conditions  to  which  the  machine  will  be  subjected. 
This  does  not  allow  for  extreme  or  exceptional  service 
which  they  are  often  forced  to  perform.  The  mi- 
chines  should  not  be  required  to  operate  for  any  length 
of  time  against  conditions  that  are  detrimental,  but 
which  unfortunately  are  continually  arising  in  actual 
practice.  It  is  surprising  to  observe  the  misuse  of 
electric   motors   on    various    applications    through    one 


RAOLI.  I'KU.KK  and  I.OI  Is  A    DKKSZ 

Mechanical    Engineer.  General    Engineer. 

Westinghouse  Electric  &  Mfg.   Company 

cause  or  another,  such  as  misalignment  of  parts, 
sprung  shafts,  incorrectly  cut  gear  teeth  and  other  me- 
chanical deficiencies  which  may  be  due  to  faulty  ma- 
chining. Additional  factors  which  may  eventually 
cause  trouble  are  lack  of  proper  lubrication  of  bear- 
ings and  gears,  and  failure  to  tighten  holding  down 
bolts  and  other  parts  liable  to  become  loose  during  op- 
eration. Frequently,  weak  and  frail  foundations  cause 
vibrations  or  even  settling,  resulting  in  excessive 
stresses  which  soon  cause  the  machine  to  fail. 

The  designer  should  provide  an  ample  proportion 
of  parts;  safe  bearing  pressures,  oil  reservoirs  of  suf- 
ficient capacity  to  provide  radiation  and  conduction  of 
the  heat  energy-  caused  by  friction  under  all  conditions 
of  normal  loading.  Under  conditions  of  misalign- 
ment, various  stresses  are  magnified  and  the  pressures 
are  in  turn  increased,  with  a  proportional  increase  of 
friction  heat.  If  this  condition  continues,  frequent 
attention  must  be  given  to  renewing  of  the  lubricant 
to  prevent  seizing  of  the  journals.  When  shafts  are 
refinished  there  must  be  a  reduction  of  journal  size 
which  has  a  very  distinct  disadvantage,  as  standard 
bearings  are  then  not  interchangeable  and  require  ad- 
ditional labor  and  expense  in  rebabbitting  of  the  bear- 
ing shell. 

In  geared  applications,  shaft  deflections  due  to 
peak  loads  have  caused  grinding  out  of  journals.     The 


September,  1921 


THE   ELECTRIC    JOURNAL 


409 


shafts  should  be  so  proportioned  to  take  care  of  such 
peak  loads  as  the  machine  may  be  called  upon  to  per- 
form. Recently,  the  bearings  of  direct-connected 
grinder  motors  wore  out  in  a  very  short  time,  because 
the  bearings  were  not  properly  protected  against  dust 
from  the  emer}^  wheel  which  entered  the  bearings  and 
scored  the  journal.  The  remedy  was  the  addition  of  felt 
washers  for  the  exclusion  of  the  dust.  Suction  fans 
are  often  installed  to  carry  away  the  emery  dislodged 
from  the  wheel.  This  has  two  distinct  advantages,  as 
it  controls  the  path  of  the  emery  dust  and  also  pre- 
vents injury  to  the  workman  from  the  promiscuous  fly- 
ing of  dust. 

In  a  rolling  mill  application,  the  motors  werq 
necessarily  placed  in  proximity  to  hot  metal.  This 
required  forced  ventilation  to  maintain  the  rated  out- 
put, which  was  accomplished  by  means   of  an  exter- 


FIG.    I — PREVENTION   OF   OIL   LE.\KAGE 

Revolving  parts  rotatiriK  at  high  speed  set  up  a  blower 
action,  creating  a  partial  vacuum  at  the  point  A.  Atmos- 
pheric pressure  within  b.earing  housing  B  tends  to  produce 
a  flow  of  air  from  within  the  bearing  housing  to  point  A 
throueh  the  clearance  space  between  the  bearing  housing  bore 
and  the  shaft  at  C.  which  will  carry  with  it  any  oil  thrown 
ofif  by  oil  throwers  D  and  still  adhering  to  the  shaft  at  the  re- 
stricted passage  C.  Where  the  partial  vacuum  at  A  exceeds 
one-half  inch  of  water  the  ordinary  dust  shield,  consisting  of 
an  annular  felt  washer  bearing  on  the  shaft  and  fastened 
against  the  end  of  the  bearing  housing  by  another  washer  of 
sheet  steel,  is  no  longer  effective  in  preventing  leakage  of  oil. 
Other  measures  then  become  necessary.  Annular  grooves  E 
are  provided  in  the  bearing,  drained  by  holes  F,  to  remove  the 
surplus  oil  from  the  bearing  before  it  reaches  the  oil  throwers 
D.  In  addition,  oil  catcher  G  and  the  three  felt  rings  H  in 
their  annular  grooves  form  an  effective  seal  against  the  pas- 
sage of  the  small /quantity  of  oil  still  remaining  on  the  shaft 
at  point  C. 

nal  blower,  the  air  playing  directly  upon  the  bearings 

and  in  a  direction  parallel  to  the  shaft.     Trouble  was 

experienced  from  this  installation  due  to  the  fact  that 

the  air  forced  the  oil  along  the  shaft  and  out  of  the 

bearing  housing,  where  centrifugal  force  threw  it  into 

the  air  currents,  which  in  turn  deposited  oil  through- 


out the  machine.  A  change  in  the  direction  of  the  air 
current  and  the  introduction  of  suitable  baffle  plates 
remedied  this  trouble.  It  is  apparent  that,  in  the  case 
of  such  applications,  provision  should  be  made  when 
selecting  the  motor,  by  using  a  different  method  of 
lubrication,  such  as  grease  or  waste  packed  bearings 
non-fluid  lubricants,  etc.  This  instance  demonstrates 
the  importance  of  making  a  close  study  of  the  actual 
application  before  selecting  the  motor. 

In  another  instance,  a  motor  was  direct  connected 
to  a  high-speed  fan,  which  set  up  considerable  suction, 
drawing  the  oil  out  of  the  housing  and  into  the  wind- 
ings. In  this  case  the  bearing  cap  was  tapped  for  an 
air  pipe  which  communicated  with  the  outside  air, 
thus  by-passing  an  air  current  which  equalized  the 
pressure  within  and  without  the  bearing.  Such  cases 
may  also  be  taken  care  of  by  adding  an  oil  shield  on 
the  inside  of  the  bearing  housing,  which  likewise  es- 
tablishes a  by-pass  for  the  air.  allowing  the  outside  air 


FIG.    1 —    l'RE\'ENTI0N    OF   OIL  LEAKAGE 

An  oil  deflector  J  is  attached  to  the  end  of  the  bearing 
housing.  Bv  the  use  of  this  device  a  chamber  K,  communi- 
cating with  the  external  atmosphere,  is  formed  just  outside 
the  bearing  housing.  The  air  in  this  chamber  will  be  at  at- 
mospheric pressure ;  conseauently  there  will  be  no  tendency 
ior  any  flow  of  a  current  of  air  from  the  interior  of  the  hous- 
ing. Anv  leakage  of  air  between  the  felt  washer  H 
and  shaft  will  be  supplied  through  chamber  K  and  not  from 
the  interior  of  the  bearing  housing  B. 

to  enter  the  machine  instead  of  drawing  it  through  the 
housing,  thus  eliminating  the  leakage  of  oil. 

Frequently  the  oil  level  is  too  high,  covering  up 
the  cored  holes  which  communicate  between  the  oil 
chambers  inside  the  housing;  a  vacuum  is  then  formed 
in  the  chamber  next  to  the  inside  of  the  machine,  due 
to  the  blowers  on  the  rotor,  which  causes  the  oil  to 
overthrow  and  be  thrown  into  the  windings.  The 
remedy  is  a  lower  oil  level  or  a  duct  in  the  bearing  cap 
which  will  establish  communication  between  the  oil 
chambers  and  equalize  the  air  pressure. 

The  correct  cutting  of  oil  grooves  is  an  important 
feature.  A  case  developed  where  the  bearings  had 
been  replaced  by  a  millwright  and  the  grooves  did  not 
communicate  properly  with  the  slot  at  the  oil  ring,  nor 


4IO 


THE    ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


were  they  carried  out  far  enough  to  povide  lubricant 
at  the  end  of  the  journal.  This  caused  heating  of 
the  bearings,  and  the  rapid  expansion  of  the  metal 
due  to  this  frictional  heating  cracked  the  housing  shell. 
Replacing  this  bearing  by  one  which  had  grooves  cut 
within  3/16  in.  of  the  annular  groove  at  the  end  of  the 
bearing,  and  also  having  grooves  well  connected  with 
the  slot  at  the  oil  rings,  provided  a  prolific  flow  of  oil 
and  remedied  this  trouble. 


FIC..^ — PREVENTION    OF    OIL    LEAKAGE 

In  this  scheme  atmosoheric  air  is  introduced  by  pipe  L 
iust  within  the  bearinff  housing  B  thus  supplying  with  air,  free 
from  oil  particles,  any  small  leakage  through  the  heavily 
washer  seal  M. 

Occasionally  a  change  in  the  composition  of  bab- 
bitt metals  is  a  remedy  for  galling  of  bearings.  For 
example,  a  150  hp  1200  r.p.m.  motor,  equipped  with  a 
4  by  10  in.  journal  and  a  16  by  16  in.  pulley  for  belted 
application  developed  a  galled  bearing.  An  investiga- 
tion of  the  bearing  reaction  showed  the  necessity  of  at- 
tention to  the  bearing  metal.  The  bearing  pressures 
were  analyzed  as  follows: — 
Belted  speed  ^V=  'JJ^  =  ^^^  X/6X/^oc;  ^.^^.^  ^^  ^^^  „,■„ 

f2  12 

Journal  Speed  =  K-lLl}Ji=~^-''"^  X4>^i2oo  =,,6oy/.Ar  «,/». 

12  12 

Pull  on  Belt  (Fig.  6)  =^=iil2<^^ 


bitt  is  poured  directly  into  the  shell,  completely  filling 
it.  The  shell  is  then  drilled  out  to  nearly  journal  size, 
then  is  bored  or  broached  to  dimension.  This  process 
is  a  waste  of  material  and  labor  and  produces  a  de- 
cidedly inferior  bearing.  A  better  method  is  to  intro- 
duce a  small  mandrel  into  the  shell  and  then  pour  in 
the  metal.  After  withdrawing  the  mandrel  the  metal 
is  broached  to  size.  This  has  the  advantage  over  the 
previous  case  in  that  it  saves  the  operation  of  boring, 
but  the  usefulness  of  the  bearing  has  not  been  in- 
creased over  the  first  method. 

The  proper  babbitting  of  the  bearing  depends  up- 
on the  temperature  at  which  the  babbitt  inetal  is 
poured,  and  the  temperature  of  the  shell  at  the  time  of 
pouring.  The  metal  temperature  is  most  readily 
maintained  at  the  proper  heat  by  means  of  an  electric 
babbitt  metal  pot,  as  shown  in  Fig.  8.  These  pots  are 
now  designed  in  nearly  all  capacities  up  to  750  pounds 
molten  metal  weight  and  are  maintained  at  a  con- 
stant temperature  by  means  of  thermostatic  control. 
The  temperature  variations  are  very  small,  insuring 
that  the  babbitt  will  be  poured  at  the  proper  tempera- 
ture, which  cannot  be  determined  by  any  haphazard 
rule  of  thumb  method.  In  all  motor  applications,  a 
first  class  quality  of  babbitt  is  an  excellent  investment. 
It  is  poor  practice  to  combine  all  of  the  various  babbitt 
metals  used  throughout  a  mill  into  one  pot  producing 
a  conglomerate  inass  of  no  definite  quality.  For  com- 
mon rough  iTiill  bearings  this  may  be  entirely  satisfac- 
torj'  but  not  for  motors,  especially  those  of  high  speed. 

The  introduction  of  a  mandrel,  approximately  one 
thirty-second  inch  smaller  than  the  finished  journal  di- 
mension and  properly  centered,  followed  by  the  pour- 
ing of  the  metal  in  a  skillful  and  scientific  manner, 
produces  excellent  operating  results.  The  reason  for 
this    is   identical    with    that    which    is   obtained    from 


fSO  X  SSOo  ^  ^S2  Ihs. 
5050 
Assuming  the  proper  co-efficient  of   friction   and   160  de- 
gree arc  of  contact,  the  total  pull  on  the  pulley  shaft  can  be 
approximated  as  .,'  P,  hence  j  /*  =  j  X  9)^2  =  29 /b  lbs. 

The  bending  moment  at  the  center  of  shaft,  Fig.  7,  is 
then  Mb  =  3  P\  =  ^9f^  X  /5  =  44200 inch-lbs.  The  sec- 
tion modulus  =  2  = -H^ — '—=  6.4.  The  stress  in  the  most 
remote  fibre  of  the  shaft  is : — 

/„  =  ^!^  =  i££££.=  6900  lbs.  per  sq.  iu. 

Z         0.4 
The  rear  bearing  reaction  is  :— 
A'  =      -'97'^  X  4i-5  ^^^^,  ihs, 

-'9-5 
Projected  area  of  bearing  is : — 

A  =  4X  JO  =  40  sq.  in. 
Pressure  per  sq.  in.  of  bearing  is : — 

p  =  ■f±i2.=  II J  lbs.  per  sq.  in. 
40 
pv  =  III  X  1260  =  139000 

While  this  product  of  journal  velocity  times  the 
unit  bearing  pressure  is  high,  it  is  still  within  operating 
limits,  provided  proper  attention  is  given  the  bearing 
metals.  In  this  case  the  lead  base  babbitt  was  changed 
to  a  tin  base  and  the  bearing  operated  satisfactorily. 
It  frequently  happens  in  repair  shops  that  the  bab- 


FIG.    4 — PREVENTION   OF  OIL  LEAKAGE 

The  communicatinc  chamber  .V  performs  to  some  extent 
the  function  of  pipe  L  in  Fig.  3.  for  if  chamber  .V  did  not 
exist  and  the  oil  level  in  the  bearing  housing  was  raised  to  the 
point  indicated,  there  would  be  no  air  passage  from  chambers 
O,  to  chamber  0=.  Then,  assuming  a  partial  vacuum  at  A, 
this  partial  vacuum  will  be  communicated  to  chamber  O-..  To 
eaualize  the  nrcsure  acting  in  chamber  O,  and  O:  the  atmos- 
pheric pressure  acting  in  chamber  O,  upon  the  bodv  of  oil, 
will  raise  the  oil  level  in  chamber  0~.  causing  leakage  at 
point  C.  With  the  introduction  of  the  communicating  cham- 
ber A'  the  pressure  eaualization  bettween  chambers  Oi  and  0-. 
is  effected  by  passage  of  air  through  passage  iv  The  same 
result  would  be  obtained  bv  using  a  pipe  such  as  L  in  Fig.  X 

chilled  casting  practice.  With  excessive  drilling  and 
broaching  the  chilled  portion  of  the  babbitt  metal  Is 
cut   away.     With   a  mandrel    very  nearly   the   journal 


September,  1921 


THE   ELECTRIC   JOURNAL 


411 


size,  the  excessive  labor  item  is  reduced,  and  the  chilled 
portion  of  the  babbitt  is  not  reduced  by  broaching,  but 
remains  as  a  wearing  surface.  This  produces  a  Beai"- 
ing  which  is  hard  but  does  not  score  under  proper  at- 
tention, is  relatively  inexpensive  and  has  a  long  life. 
Under  the  most  severe  conditions,  it  may  become 
necessary  to  roll  the  babbitt  by  means  of  a  hardened 
steel  roller,  introduced  within  the  bearing  shell,  the 
bearing  shell  being  turned  against  this  roller  under 
pressure.  For  geared  motor  applications,  where  the 
service  is  severe,  it  is  often  advisable  to  resort  to 
bronze  bearing  shells  with  a  tinned  bearing  surface. 
The  bearing  is  first  turned  to  size  and  after  tinning  it 
is  broached.  The  tin  is  almost  entirely  absorbed  hy 
the  metal,  filling  the  pores  and  thus  forming  a  smooth 
bearing  surface,  hard  and  durable,  and  which  will  not 
peen  out  under  the  vibrations  which  are  characteristic 
of  this  class  of  service*. 

In  general,  it  should  be  observed  that  journal 
speeds  should  not  exceed  practical  limits,  particularly 
where  the  bearing  pressures  run  high.  Ordinari- 
ly, it  is  considered  good  practice  to  maintain  1200  feet 


FIG.   S —  AN  EFFECTIVE  SEAI.  WHERE  THE  DIREC.IO.V   UP   ROTATION   IS 
CONSTANT 

A  chamber  Q  is  formed  bv  oil  shields  R  and  6"  through 
which  the  shaft  passes.  Pressure  in  this  chamber,  greater  than 
the  atmosolicric  oressure  actine  in  other  chambers  of  the  bear- 
ing housing,  is  maintained  by  use  of  collar  T,  secured  to 
the  exterior  of  the  bearing  housing.  Collar  T  and  the  end 
of  the  bearing  housing  are  threaded  as  shown,  so 
that  the  end  of  the  thread  clears  the  shaft  by  a  small  mar- 
gin. The  threads  are  cut  right  hand  and  left  hand,  depend- 
ing upon  which  end  of  the  motor  is  considered  and  the  di- 
rection of  rotation,  to  secure  the  result  that  air,  travelling 
around  with  the  shaft  within  the  threaded  section,  is  caused 
bv  friction  to  follow  the  threads  and  pass  axially  into  the  in- 
terior of  the  housing.  In  this  way  pressure  instead  of  par- 
tal  vacuum  is  created  in  chamber  Q,  counteracting  the  effect 
of  the  partial  vacuum  at  point  A. 

per  minute,  at  bearing  pressures  not  exceeding  150  lbs. 
per  square  inch  belted  load. 

This  leads  to  the  consideration  of  belt  speeds, 
which  should  not  be  over  5000  feet  per  minute;  other- 
wise centrifugal  force  tends  to  lift  the  belt  oiT  the  pul- 
ley, reducing  the  efficiency**.  The  following  il- 
lustrates a  case  where  a  rubber  belt  was  used  with  a 
75  hp  motor.     The  belt,  after  a  short  period  of  opera- 


*For  a  more  detailed  description  of  babbitting  methods 
see  Westmghouse  Folder  No.  4474  entitled  "No.  25  Alloy"  bv 
T.  D.  Lynch. 

**See  article  on  "The  Determination  of  Pulley  and  Belt 
bizes'  by  C.  B.  Mills,  in  the  Journal  for  Sept.  igio,  p.  729. 


tion  showed  a  defect  from  manufacture.  On  the  driv- 
ing side  a  slight  opening  developed,  admitting  air 
which,  on  passing  over  the  pulley,  was  compressed 
along  the  belt  for  a  distance  of  some  three  feet.  As 
the  air  pocket  approached  the  pulley,  the  belt  inflated 
to  a  thickness  of  about  four  inches  before  it  passed 
around  the  arc  of  contact.  Upon  release  of  the  pres- 
sure the  air  discharged  with  a  loud  report ;  the  bearing 
became  hot  due  to  excessive  stress  caused  By  the  bag 
of  trapped  air.  The  remedy  was  a  number  of  slits  cut 
in  the  top  ply  of  the  belt,  parallel  to  its  length,  permit- 
ting the  air  to  escape. 

In  certain  industries,  such  as  textile  and  cement 
mills,  the  belts  are  pulled  to  a  tension  which  approach- 
es the  breaking  point,  for  the  purpose  of  preventing 
slip.  If  the  ordinary  commercial  motor  is  used  for 
such  duties,  the  shaft  deflections  become  excessive  and 
may  cause  rapid  bearing  wear  and  reduction  of  the 
air-gap,  which  is  necessarily  small  for  high  efficiency 
and  high  power-factor  alternating-current  motors.  In 
a  cement  mill  such  a  condition  was  demanded;  and  to 
insure  proper  ojjeration  a  75  hp  motor  was  redesigned 
with  a  shaft  nine  inches  in  diameter  to  reduce  the  ex- 
cessive deflection  which  would  have  prevailed  had  a 
standard  motor  been  applied. 

Generally,  a  standard  motor  should  be  chosen  for 
the  following  reasons : — 

I — Design  troubles  have  been  eliminated  by  rigid  tests 
and  standard  processes  before  the  motor  is  offered  for 
sale  in  the  open  market. 

2— Prompt  shipment  can  be  made  from  stock,  and  if 
not,  they  can  usually  be  built  up  quickly  from  standard 
stock  parts. 

3 — The  cost  is  less  than  for  a  special  motor,  because 
advantage  can  be  taken  of  quantity  production. 

4 — The  user  can  standardize  the  motors  installed  to  a 
large  extent  and  thus  reduce  spare  parts.  This  spare  stock 
multiplies  very  rapidly  as  odd  types  of  motors  are  installed. 

5— Reducing  the  number  of  spare  parts,  reduces  the 
amount  of  capital  invested  for  material  that  may  not  turn 
over  for  some  considerable  period  of  time. 

6 — Renewal  parts  are  more  readily  obtained  as  they 
can  usually  be  supplied  from  factory  stock. 

With  the  large  number  of  sizes  available,  a  mo- 
tor can  usually  be  selected  that  will  perform  the  duty 
required.  Possibly  some  slight  modification,  such  as 
gear  ratio,  will  allow  proper  speeds  to  be  obtained.  If 
this  is  possible  it  facilitates  standardization  with  the 
advantages  enumerated  above. 

Cases  of  trouble  occur  where  consideration  has 
not  been  given  to  the  correct  mounting  of  the  pulley 
or  gear  upon  the  shaft  extension,  frequently  referred 
to  as  the  "overhang"  of  the  pulley  or  gear.  If  the  pul- 
ley is  mounted  at  an  extreme  distance  from  the  center 
of  the  bearing,  the  stresses  in  the  sh.ift  are  increased  in 
direct  proportion  to  the  distan...;:  from  the  center  of 
the  bearing  to  the  point  of  application  of  the  load;  in 
other  words,  if  the  distance  from  center  of  bearing  to 
center  of  pulley  or  gear  is  doubled,  the  resulting  bend- 
ing stresses  are  doubled.  The  deflections  produced 
increase,  however,  approximately  with  the  cube  of  the 
distance;  i.  e.,  if  the  distance  is  doubled  the  deflection 
will  be  approximately  eight  times  as  great.     Due  at- 


412 


THE    ELECTRIC    JOURNAL 


Vol.  XVIII,  No.  9 


tention  should  be  paid  to  the  location  of  the  gear  or  pul- 
ley in  order  to  reduce  these  stresses  and  deflections  to  a 
minimum.  There  is  a  practical  limit  within  which  this 
may  be  accomplished.  The  pulley  or  gear  should  be 
mounted  to  allow  just  enough  space  between  it  and  the 
face  of  the  bearing  housing,  to  permit  reaching  be- 
hind it,  should  it  become  necessary  to  remove  the  pul- 
ley or  gear.  Where  taper  keys  are  used,  space  must 
be  allowed  to  permit  the  inserting  of  a  wedge  or  bar 
to  remove  the  key  without  injuring  any  of  the  adja- 
cent parts.  Where  loose  and  tight  pulleys  are  re- 
quired, it  is  obviously  a  gross  error  to  mount  the  loose 
pulley  between  the  tight  pulley  and  the  bearing  hous- 
ing, since  the  loose  pulley  transmits  no  power,  hence, 
exerts  no  appreciable  pull ;  however,  upon  shifting 
the  belt  to  the  tight  pulley,  the  belt  tension  due  to  the 
load  is  then  applied  at  a  maximum  point  from  the  bear- 
ing center,  which  subjects  the  shaft  to  an  excessive 
stress.  Hence,  for  successful  operation,  the  tight  pul- 
ley should  always  be  next  to  the  bearing  housing  and 
the  loose  pulley  outside. 

Where  machines  are  directly  coupled,  the  center 
of  the  driven  shaft  should  coincide  with  the  center  of 
the  driving  shaft.  It  is  "sometimes  found  that  ma- 
chines are  mounted  directly  upon  concrete  founda- 
tions, and  shimmed.     This  is  not  good  practice,  as  vi- 


FIG.    6 — PULL   ON    BELTS  FIG.     7 — BEARING     PRESSURES 

brations  may  disintegrate  the  concrete  and  allow  the 
machines  to  get  out  of  alignment.  It  is  best  to  mount 
coupled  machines,  on  a  cast-iron  bedplate,  accurately 
machined  on  both  top  and  bottom  sides.  The  ma- 
chining of  the  bottom  is  of  great  assistance  when 
mounting  sets  in  the  shop,  as  it  facilitates  assembling 
and  prevents  springing  or  rocking  of  the  bedplate. 
The  advantage  of  a  cast-iron  bedplate  is  further  shown 
when  the  fact  is  considered  that  dowel  pins  should  be 
used  for  securing  machines  after  they  are  placed  in 
their  proper  positions.  Dowel  pins  should  be  located 
on  the  coupling  end  and  at  least  two  dowels  used  per 
machine.  This  will  permit  removal  of  the  machines 
to  change  armatures  or  couplings.  A  cast-iron  plate 
also  permits  the  proper  tightening  of  foundations  bolts 
without  danger  of  crushing  the  foundation,  as  may  be 
the  case  with  brick  or  concrete. 

Couplings  should  have  an  "iron  to  iron  tit,"  which 
means  that  both  the  coupling  bore  and  the  shaft  dia- 
meter are  of  exactly  the  same  dimensions.  Mill- 
wrights often  insert  a  coupling  or  gear  in  a  bath  of 
boiling  water,  which  facilitates  forcing  them  on  the 
shaft.  In  the  case  of  sprocket  wheels,  this  is  of  parti- 
cular merit  since  it  may  be  necessary  to  repair  the 
chain,  and  the  wheel  can  be  removed  without  difficulty. 


Again,  it  may  be  necessary  to  change  the  gear  ratio,  or 
replace  a  worn  out  gear;  in  such  cases  a  tight  fitting 
gear  is  a  source  of  great  annoyance  and  there  are  cases 
where  it  became  necessary  literally  to  cut  the  gear  from 
the  shaft.  Motors  which  have  solid  bearings  and 
brackets,  should  never  have  the  coupling  or  gear  too 
tightly  mounted.  A  bumping  fit  is  most  satisfactory 
and  will  prove  a  time  saver. 

With  high-speed  pinions,  poor  meshing  of  the- 
teeth  creates  considerable  noise,  and  rapid  wear.  The 
proper  key  for  such  mounting  is  a  feather  key  with 
clearance  on  the  top  and  snugly  fitting  at  the  sides. 
A  poorly  fitted  key  or  pinion  will  endanger  not  only 
the  machine,  but  may  become  a  hazard  to  workmen. 
Under  the  continued  vibration  to  which  these  machines 
are  necessarily  subjected,  the  pinion  and  gear  eventu- 
ally may  work  loose,  if  proper  fits  are  not  maintained. 
Shafts  are  often  damaged  in  the  keyway  from  negli- 
gent fits,  especially  with  motors  used  on  reversing  du- 
ty. With  the  advent  of  electric  welding,  it  is  now  pos- 
sible to  build  up  the  shaft. 


FIG.     8 — ELECTRICALLY- HEATED     BABBITTING     INSTALLATION 

The  control  is  mounted  on  the  column 

A  convenient  and  satisfactory  way  of  mounting  a 
pinion  is  the  use  of  a  taper  shaft  end.  This  is  more 
expensive,  but  for  severe  service,  such  as  mill  or  rail- 
way work,  it  is  found  to  be  necessary.  A  taper  fit  per- 
mits easy  removal  of  the  pinion,  and  insures,  not  only  a 
good  and  tight  fit  but  a  true  fit  as  well. 

Although  taper  fits  are  desirable  for  gears,  pinions 
and  solid  couplings,  they  are  not  practical  for  flexible 
connections,  on  account  of  the  space  required  by  the 
nut  which  forces  the  coupling  half  upon  the  tapered 
end  of  the  shaft.  It  is  commonly  thought  that  a  flexi- 
ble coupling  is  a  cure  for  all  misalignments,  regardless 
of  their  occurrence.  This  is  true  only  to  a  limited  de- 
gree. The  real  purpose  of  resorting  to  a  flexible  coup- 
ling or  connection  is  to  absorb  shocks  in  order  to  pro- 
tect the  motor. 

To  choose  a  solid  or  flexible  coupling,  the  charac- 
ter of  the  load  in  each  specific  instance  should  first  be 
considered.     If  the  load  is  of  the  uncushioned  charac- 


September,  1921 


THE   ELECTRIC   JOURNAL 


413 


ter  such  as  a  metal  working  machines,  a  flexible 
coupling  should  be  selected.  Where  perfect  align- 
ment or  a  continuous  steady  load  can  be  maintained, 
a  solid  coupling  should  be  selected.  As  a  general  rule, 
solid  couplings  are  used  for  connections  between  shafts 
whose  bearings  are  mounted  upon  the  same  rigid  iron 


FIG.    9 — PORTABLE    ARC    WELDING    OUTFIT 

In  addition  to  building  uo  damaged   shafts,  such  an  out- 
fit can  be  used  for  innumerable  applications  in  a  modern  shop. 

foundation,  bedplate  or  frame  work.  Where  the  ma- 
chines are  liable  to  drop  ottt  of  the  alignment,  a  flexible 
unit  should  be  installed. 

In  the  selection  of  flexible  couplings  several  points 
should  be  borne  in  inind; — first,  any  part  which  is 
subjected  to  wear  and  tear,  must  eventually  be  re- 
placed. Therefore,  the  coupling  should  be  simple  of 
design  and  construction,  and  capable  of  having  the 
worn  parts  easily  replaced.  Too  frequently  the  flexi- 
ble features  of  couplings  require  special  parts  which 
must  be  kept  in  stock;  if  the  coupling  fails  and  these 
parts  are  not  on  hand,  a  makeshift  of  some  kind  must 
be  devised.  Second,  the  coupling  should  be  symmetri- 
cal and  well  balanced.  Third,  to  eliminate  delays  dur- 
ing repairs,  the  adjacent  parts  should  be  accessible,  for 
in  case  of  failure  more  time  may  be  consumed  in  dis- 
mantling, than  in  the  actual  repair  and  reassembly. 
Fourth,  the  number  of  actual  working  parts  should  be 
a?  few  as  possible,  as  this  facilitates  handling  and 
quick  replacement. 

If  the  shaft  has  a  solid  flange  forged  on,  by  which 
it  is  coupled  to  the  adjacent  members,  the  shaft  is 
sometimes  turneid  down  in  order  to  keep  the  diameter 
of  the  flange  as  small  as  possible  and  permit  insertion 
of  the  bolts  for  a  short  distance.  Experience  has  shown 
that  this  is  dangerous  practice  since  a  slight  degree  of 
misalignment,  may  cause  a  bending  of  the  shaft,  which 
is  concentrated  in  the  turned  down  section. 

When  there  are  liable  to  be  sudden  shocks,  a  flexi- 
ble coupling  should  be  used  to  protect  the  motor.  This 
should  be  done  for  the  same  reason  for  which  the  mill- 


wright uses  a  "wobbler"  coupling, —  to  protect  the  ap- 
paratus which  is  vital,  and  whose  repair  would  be  cost- 
ly. Not  only  is  this  true  in  cases  of  shocks  but,  with 
certain  loads  where  vibrations  are  carried  directly  10 
the  motor  and  parts  through  the  solid  connection.^, 
blower  vanes,  rivets,  even  motor  frames  will  break, 
due  to  crystallization.  Rotor  bars  may  break  loose 
from  the  end  rings;  and  leads,  exposed  to  such  vibra- 
tions may  break,  causing  short-circuits,  and  serious 
damage  to  the  machine.  For  all  such  classes  of  serv- 
ice the  flexible  coupling  is  a  protection.  Many  cases 
of  break  down  have  been  due  directly  to  lack  of  this 
feature ;  subsequent  installations,  using  a  flexible 
coupling,  have  proved  successful  thus  bearing  out  the 
importance  of  having  a  cushioned  element. 

Where  a  motor  is  geared,  the  application  of  a 
flexible  coupling  is  not  always  possible,  though  it  may 
sometimes  be  accomplished  by  using  an  intermediate 
shaft.  Gears  may  cause  considerably  shock,  when  re- 
versing under  load,  due  to  the  ba:ck  lash  between  the 
teeth:  For  this  reason  gears  should  be  machine  cut, 
and  of  the  best  of  material,  so  as  not  to  wear  rapidly. 
Pinions  should  be  made  of  forged  steel,  heat  treated. 
Meshing  gears  for  steel  mill  work  should  be  cast  steel, 
as  it  has  been  found  that  the  severe  service  imposed 
upon  them  cause  an  uneven  wear  of  cast-iron  teeth. 


Effect  of  Connecting  a  Genera- 
tor to  the  Line  Out  of  Phase 


D.  GOODFELLOW 


This  900  kvv,  25  cycle,  6  pole,  2300  volt  generator  delivered 
its  rating  for  several  months  after  receiving  the  "bump".  The 
winding  plainly  shows  the  six  points  where  the  short-circidt 
stresses  must  have  centered. 


Motor  J)iMVo.ii  .PJaco 


s 


PLATE  mills  are  divided 
classes — sheared  plate  mills  and  universal  plate 
mills.  The  original  plate  mills  were  two-high  and 
non-reversing,  passing  the  plate  back  over  the  top  roll 
idle.  This  mill  was  expensive  in  the  use  of  labor  and 
wasteful  in  the  temperature  of  the  plates.  This  was 
followed  by  the  two-high  reversing  mill  which,  while 
eliminating  considerable  labor  and  allowing  the  plates 
to  be  rolled  thinner  than  was  possible  with  the  two- 
high  non-reversing  mill,  yet  was  expensive  in  its  op- 
eration, due  to  the  use  of  the  reversing  steam  engine. 
The  next  development  in  this  country  was  the  intro- 
duction of  the  three-high  mill.  This  mill  allowed  the 
use  of  a  non-reversing  engine.  It  was  as  fast  as  the 
two-high  reversing  steam-driven  mill  and  rolled  a 
plate  with  better  finish  than  was  obtained  from  the  two- 
high  mill.  The  highest  development  of  the  three- 
high  mill  is  the  Lauth  type,  which  is  almost  universally 
used  in  this  country  for  rolling  sheared  plate. 

TWO- HIGH    MILL 

The  simplest  of  the  two  mills  used  in  this  count 
try  today  for  rolling  sheared  plate,  is  shown  schema  t: 

Mill  D.  C  Motor 


F.  D.  EGAN 

Steel  Mill  Engineer, 
Westinghouse  Electric  &  Mfg.  Company 

into  two  general  pinion  was  driven  and  was  located  on  the  same  cen- 
ter line  as  the  top  and  bottom  pinions  and  was  usually 
about  two-thirds  the  pitch  diameter  of  the  main  pinion. 
Below  is  shown  a  set  of  Kennedy  pinion  housing 
which  allows  a  reduction  of  from  4  or  5  to  i.  This 
pinion  housing  allows  the  use  of  a  higher  speed  motor, 
while  on  the  older  drives  the  motor  speed  was  deter- 
mined entirely  by  the  speed  of  the  main  rolls. 

A  160  inch  three-high  Lauth-type  plate  mill  is 
shown  in  Fig.  4  as  installed  at  the  Gary  Plant  of  the 
Indiana  Steel  Company.  This  is  the  largest  three-high 
plate  mill  that  has  been  built.  Fig.  5  shows  the  7000 
hp  motor  driving  this  mill*,  the  largest  steel  mill  mo- 
tor that  has  been  built  to  date.  It  is  a  specially  designed 
motor  developing  a  starting  and  pull  out  torque  of 
30000  hp.  The  flywheel  is  assembled  in  the  rotor  of 
the  motor  which  is  direct  connected  to  the  lead  spindle 


FIG.   I — TYPICAL  DRIVE  FOR  TWO  HIGH  REVERSING  PLATE  MILL 

cally  in  Fig.  i,  consisting  of  two  plain  horizontal  rolls. 
Both  the  top  and  bottom  rolls  are  driven  by  spindles 
from  a  two  high  stand  of  pinion  housings.  The  loca- 
tion of  the  bottom  roll  is  fixed  but  the  top  roll  is  raised 
and  lowered  by  an  electric  screw  down,  operating 
against  a  hydraulic  cylinder  at  constant  pressure. 

The  two  high  mills  are  used  for  producing  plate 
when  the  finish  is  not  so  important  and  are  also  used 
for  roughing  mills  in  tandem  combinations.  A  two  high 
reversing  plate  mill  is  shown  in  Fig.  2. 

THREE-HIGH   MILL 

'  A  typical  three-high  Lauth-type  plate  mill  is 
shown  in  Fig.  3,  consisting  of  three  plain  horizontal 
rolls,  the  middle  roll  beJfig  smaller  than  the  other  two. 
The  top  and  bottom  rolls  are  driven  in  the  same  direc- 
tion by  spindles  from  a  pinion  housing,  while  the  mid- 
dle roll  is  alternately  driven  by  the  top  and  bottom  roll 
by  friction. 

In  the  older  mills,  pinion  housings  were  arranged 
as  shown  in  the  upper  part  of  Fig.   3.     The  middle 


FIG.    2 — 84    INCH    COMBINATION    PLATE    MILL 

Enterincr  side  of  rouehine  stand  in  forceround. 

of  the  mill  pinion  housing.  It  is  difiicult  to  embody 
adequate  flywheel  eflfect  in  the  rotor  of  a  motor,  but 
this  motor  is  connected  to  a  large  power  system,  so 
that  full  equalization  of  the  load  is  not  essential. 

Fig.  6  shows  the  5000  hp  motor  driving  the  plate 
mill  of  the  Brier  Hill  Steel  Company.  The  motor  is 
direct  connected  to  a  separate  flywheel  mounted  in  its 
own  bearings  and  direct  connected  to  the  pinion  shaft 
of  the  Kennedy  pinion  housing.  The  motor  operates 
at  197  r.p.m.  while  the  main  rolls  operate  at  approxi- 
mately 46  r.p.m.  giving  a  speed  reduction  of  about  4.3 
to  I. 

UNIVERSAL   MILL 

A  typical,  two-high,  universal  plate  mill  is  shown 
in  Fig.  7,  consisting  of  a  set  of  two-high,  plain  cylin- 

*This  motor  was  described  in  the  Journal  for  June  1919, 
p.  2S4  by  Mr.  H.  L.  Bamholdt. 


September,  192 1 


THE   ELECTRIC   JOURNAL 


415 


drical,  horizontal  rolls  and  two  sets  of  plain  cylindri- 
cal, vertical  rolls,  one  set  of  vertical  rolls  being  lo- 
cated on  each  side  of  the  main  horizontal  rolls.  Both 
sets  of  vertical  rolls  are  independently  adjustable  by 
means    of    electrically-operated    screws.     The    product 

Mill  '''^""'"' 

k— Pinions 


FIG.  3 — TYPICVL  DRIVE  FOR  THREE  HIGH  PLATE  MILL 

of  this  mill  is  relatively  narrow  when  compared  to 
plates  rolled  on  the  two  or  three-high  mill  rolling' 
sheared  plate. 

The  60  inch  univei'sal  plate  mill  at  the  Sparrows 
Point  Pknt  of  the  Bethlehem  Steel  Company  is  shown 
m  Fig.  8.  This  is  the  largest  mill  of  this  type  that 
has  been  built**  and  is  designed  to  roll  13  by  62  inch 
10  000  lb.  slabs  to  Yg,  inch  by  60  inch  plate  in  21  passes, 
passes. 

An  exception  to  the  two-high  universal  plate  mill 
described  above  is  the  three-high  universal  plate  mill 
at  the  Indiana  Steel  Company  Gary  plant.  This 
mill  is  driven  by  a  two-speed  motor. 

COMBINATION   MILLS 

In  rolling  veiy  thin  plate,  or  where  tlie  production 
should  be  increased,  combination  mills  have  been  in- 
stalled. These  mills,  with  one  e.xception,  consist  of 
two  stands  of  three-high  rolls  arranged  in  tandem  and 
are  usually  about  84  to  90  inch  mills  of  the  Lauth  type. 

Fig.  9  shows  the  arrangement  of  two  stands  of 
three-high  rolls  forming  a  tandem  plate  mill.  In  this 
arrangement,  the  three-high  roughing  mill  is  driven 
through  a  set  of   cut  herringbone   pinions   by   a   slow- 


through  a  standard  herringbone  gear  unit  with  the  fly- 
wheels located  on  the  pinion  shaft  of  the  gear  unit. 
The  slow-speed  shaft  of  the  gear  unit  is  coupled  to 
the  lead  spindle  of  the  cut  herringbone  pinions.  It 
should  of  course  be  understood  that  both  stands  of  a 
tandem  mill  can  be  driven  by  motors  direct  connected, 
as  is  shown  for  the  roughing  stand,  or  by  geared  mo- 
tors, as  is  indicated  for  the  finishing  stand.  In  a  num- 
ber of  instances  both  stands  are  driven  as  is  shown  for 
the  mill  on  the  lower  half  of  Fig.  3. 

During  the  development  of  the  present  three-high 
plate  mills,  the  two-high  reversing  mill  was  superseded 
by  the  three-high  mill,  due  to  questions  of  economy 
and  price  of  the  reversing  engine.  In  arranging  tan- 
dem combination  mills,  it  was  natural  to  follow  the 
practice  of  steel  mills  using  single-stand  plate  mills, 
and  to  build  the  tandem  mills  with  a  three-high  rough- 
ing and  finishing  stand. 

The  84  inch  tandem  plate  mill  of  the  Brier  Hill 
Steel  Company— the  exception   niriiti(  mhmI   ■a]u,\^-     n.^. 


I'jH    LAI   rii-riPE   PL.^TE   MILL 

speed  motor,,  with  a  flywheel  located  between  the  motor 
andjDinion     housing.     The    finishing    mill    is     driven 

bvMr'^R'^R'r°T^?^'  "'^    eauinment    fo,    driving    this    mill 
'020      ,6,     •  ^''^'''^'  ^"^  ""'''■^hed  in  the  Journal  for  sTpL 


FIG     ?— 7000    HP    INDUCTION    MOTOR    DRIVING    THE    MILL    SHOWN   IN 
FIG.   4 

This  is  the  largest  mill  motor  yet  built 
a  two-high  roughing  stand  and  a  three-high  finishing 
stand,  both  electrically  driven,  as  shown  in  Fig.  10" 
The  production  of  this  mill  proves  that  the  inotor- 
driven  reversing  roughing  stand  gives  a  much  faster 
mill  than  a  tandem  mill  with  a  motor-driven  three-high 
roughing  stand.  The  characteristics  of  the  reversing 
steam  engine  do  not  provide  the  exactness  of  control 
necessary  for  operating  the  roughing  stand  fast  enough 
to  duplicate  the  tonnage  of  this  mill.  Due  to  the 
rapidity  of  operation  of  the  roughing  mili;  it  is  possible 
to  roll  a  plate  to  a  smaller  gauge  than  has  been  found 
possible  with  tandem  mills  using  a  three-high  rough- 
ing stand. 

An  oscillogram  taken  on  the  direct-current  mo- 
tor driving  the  roughing  stand  of  the  Brier  Hill  84 
inch  tandem  plate  mill  is  reproduced  in  Fig.  n  This 
oscillogram  was  taken  while  the  mill  was  rolling  3  by 
17  by  41%  inch,  600  lb.  slabs  to  3/16  inch  plate,  "seven 
passes  were  taken  in  the  roughing  stand  and  the  plate 
was  then   finished   in   the   three-high   stand.     The  milll 


4i6 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  9 


was  rolling  one  slab  every  20  seconds,  this  time  includ- 
ing the  intervals  between  the  slabs,  as  well  as  the  inter- 
vals between  passes.  At  this  rate  the  mill  was  operating 
at  the  rate  of  180  slabs  an  hour,  while  the  record  on  this 
mill  is  220   slabs  an  hour  or  when  the   ossillogram  was 


justable-si)eed  drive,  although  such  a  drive  has  never 
been  used  in  this  country  for  driving  plate  mills.  In 
England  a  direct-current  motor  and  flywheel  motor- 
generator  set  are  being  installed  for  driving  a  three- 
high  plate  mill,  the  speed  of  the  motor  being  adjusta- 
ble over  a  wide  range.. 


FH;.   0 — 5000   HP  INDUCTION    MOTOR   DRIVING   A    \  T,2   INCH    THREE 
HU;H     PLATE    .VI  ILL 

taken,  the  mill  was  operating  only  82  percent  as  fast  as 
the  mill  record.  An  insi)ection  of  Fig.  11  shows  that  the 
seven  passes  were  made  in  15.6  seconds  or  an  average 
of  one  pass  every  2.21  seconds  which  includes  the  dura- 
tion of  pass,  the  reversal  and  the  interval  between 
passes;  pass  4  was  made  in  1.8  seconds.  Very  little  dif- 
ference in  time  was  required  in  the  duration  of  the  dif- 
ferent passes,  due  to  the  increase  in  delivery  speed  of 
the  rolls  to  suit  the  individual  pass.  Fig.  12  shows  the 
electrical  equipment  for  driving  this  mill*,  and  the  mill 
itself    is  shown  in  Fig.  2. 

TYPES  OF  DRIVE 

Present  practice  embraces  two  types  of  drives. 
First,  the  constant-speed,  three-high  mill  driven  by  an 
induction  motor.     Second,  the  two-high  reversing  mill 


FIG.   7 — TYPIC.\L  DRIVE  FOR  A  TWO   HIGH  REVERSING  UNIVERSAl. 

PLATE    MILL 

driven  by  a  reversing  direct-current  motor  having 
a  wide  range  of  speed.  Merchant  mills,  structural 
mills  and  rail  mills  call  for  an  alternating-current  ad- 


FIU.   S — 63   INCH    UNIVERSAL   PLATE    MILL 

This  is  the  largest  mill  of  this  type  yet  built 

There  are  three  general  method--  of  driving  three- 
liigh  Lauth  mills: — 

' — Dircct-conncct  the  motor  to  the  flywheel  shaft  by 
means  of  a  flexible  coupling  and  connect  the  flywheel 
shaft  to  the  lead  spindle  by  means  of  a  mill  coupling,  as 
shown  in  Fig.  3,  The  flywheel  bearing  next  to  the  mill 
should  be  equipped  with  a  thrust  bearing. 

J — Direct-conncct  the  motor  by  means  of  a  flexible 
coupling  to  the  high-speed  shaft  of  the  herringbone  gear 
unit  with  the  flywheel  located  between  the  slow-speed 
shaft  of  the  gear  unit  and  the  mill;  or  use  two  high-speed 
flywheels  on  the  pinion  shaft  of  the  gear  unit,  and  direct- 
connect  the  slow-speed  shaft  to  the  mill.  Both  of  these 
methods  are  shown  in  Fig.  9. 

3--Direct-connect  the  motor  to  the  flywheel  shaft  by 
means  of  a  flexible  coupling,  and  connect  the  flywheel 
shaft  to  the  pinion  shaft  of  a  Kennedy  pinion  housing,  as 
shown  in  l-'ig.   10. 

The  cost  of  a  motor  for  such  drives  will  decrease 
and  the  electrical  performance  will  be  improved  with 
an  increase  in  speed.  In  order  to  compare  the  slow- 
speed  drive  with  a  high  speed  unit,  the  cost  of  the  gears 


*A  complete  description  of  this  equipment  «.as  published 
in  an  article  by  G.  H.  Haney  in  the  Journal  for  May  1919, 
o.  188.  * 


FIG.    0 — TYPICAL    DRIVE    FOR    A    THREE    HIGH    tO.MBIXATION    TANDEM 
PL,\TE    MILL 

must  be  included  with  the  cost  of  the  high-speed  moto'-. 
If  it  is  necessarj'  to  give  consideration  to  power- factor 
correction,  the  cost  of  the  necessary  corrective  appara- 
tus must  be  included  with  the  slow-speed  motor,  this 
equipment  being  of  sufficient  capacity  to  give  the  same 
power-factor  as  the  high-speed  motor.  The  cost  of 
the  flywheels,  necessary  bearings  and  couplings  will 
likewise  have  to  be  compared  before  a  final  decision 


September,   192 1 


THE   ELECTRIC   JOURNAL 


417 


can  be  made  as  to  the    equipment    that    should    be    in- 
stalled. 

CONTROL 

The  control  for  a  constant-speed  motor  drive  is 
sliown  in  Fig.  13.  It  consists  of  a  forward  and  reverse 
oil   circuit  breaker  and  a  liquid  slip  regulator  for  the 

Mill  ^-  C.  Motor 

Pinions 


It  more  nearly  approaches  the  ideal  condition  of  con- 
serving the  flywheel  effect  until  the  motor  is  fully 
loaded.  At  the  end  of  the  pass,  the  load  on  the  motor 
is  sustained  until  the  flywheel  has  been  returned  to  its 
normal  light-load  speed*. 

From  the  performance  of  the  liquid  type  regulator 
it  is  apparent  that  it  is  best  suited  for  plate  mill  appli- 
cations and  can,  therefore,  be  selected  regardless  of 
whether  the  motor  and  flywheel  be  directly  connected 
or  geared. 


FIG.    10— TYPICAL   DRIVE    FOR    .\    COMBINATION    TANDE.M    PLATE    MILI 

WITH   TWO   HIGH    REVERSING  ROUGHING   STAND   AND  A   THREE 

HIGH    FINISHING    STAND 

secondary  control.  There  are  three  methods  of  con- 
trolling the  secondary  of  a  wound  motor  induction  mo- 
tor. The  first  is  to  have  a  permanent  amount  of  slip 
resistance  in  its  secondary  circuit;  the  second  uses 
notch-in  relays  in  conjunction  ^N\th.  the  secondary  re- 
sistance and  the  third  is  by  liquid  slip  regulator. 

With  a  permanent  slip  resistance  in  the  secondary 
of  an  induction  motor,  its  speed  drops  off  in  direct  pro- 
portion to  the  load.  This  scheme  does  not  utilize  the 
flywheel  to  its  best  advantage,  as  the  flywheel  should 
not  be  called  upon  to  give  up  energ}'  until  the  motor 
has  first  been  fully  loaded. 

A  modification  of  control  em- 
ploying    fixed     resistance     is     ob- 
tained by  the  addition  of  notch-in 
relays.     With  this  type  of  control 
a  permanent  amount  of  resistance, 
say  five  percent,   is  placed  in   the 
secondary.        When      the      motor 
reaches  its  full  load,  additional  re- 
sistance   is    inserted    in    the    rotor 
circuit,    causing    the    flywheel    to 
carry  a  greater  proportion  of  the 
peak  load.     This  type  of  control  is 
too  slow  in  inserting  the  additional 
resistance  to  allow  the  fl^'wheel  to 
absorb  the  peak.     In  addition    the 
frequent  closing  of  the  heavy  con- 
tactors resulted  in  so  much  trouble 
that     the     notch-in     relays     were 
usually  disconnected  and  the  drive 
operated  with  fixed  permanent   resistance,  or  the  en- 
tire secondary   control   was   replaced   by   a   liquid   slip 
regulator. 

The  use  of  the  liquid  slip  regulator  in  the  second- 
ary IS  an  improvement  over  the  preceding  schemes,  as 


FIG.    I  r— OSCILLOGRAM    OF   MOTOR  DRIVING   THE  ROt'GHING   STAND  OF 
THE   MILL   SHOWN   IN   FIG.   2 

A-Speed  curve.  B-Vo!tage  curve.  C— Current  curve 
Niunbers   i   to  7  nidicate  the  various  oasses.     The  time   is  in- 
dicated ni  seconds  along  the  zero  line. 

REVERSING    DRIV^E 

The  electrical  equipment  for  driving  a  reversing 
mill  is  more  expensive  than  is  required  for  driving  the 
three-high  mill,  yet  the  total  costs  of  the  mill  and  drive 
installed  are  about  the  same  for  the  two  types.  The 
production  of  the  tandem  mill  using  a  two-high 
roughing  stand  is  much  higher  than  that  of  a  tandem 
mill  with  a  three-high  roughing  stand.  At  the  Brier 
Hill  Steel  Company's  plant  there  are  more  delays  on 
the  three-high  finishing  stand  than  on  the  two-high 
roughing  stand.  Fig.  14  shows  a  schematic  diagram 
of  a  double  unit  reversing  motor  drive.  The  motor 
is  rigidly  coupled  to  the  lead  spindle  of  the  pinion 
housing  by  means  of  a  universal  coupling.     The  power 


- — KEVERSING 


EOUIPMFNT     FUR     IJMMM.    I  HE    Rni;,,HIN(;    STAND 
COMBINATION  MILL  SHOWN  IN  FIG.  2 


r>F    THE  84   l\cn 


■The  characteristics  of  a  motor  operating  with  fixed 
secondary  resistance,  with  notch-in  relays,  and  with  the  liquid 
type  regulator  are  discussed  in  detail,  with  motor  speed-torque 
curves  and  graphic  meter  records  in  an  article  on  "Electrical- 
Driven  Plate  Mills  by  G,  E.  Stoltz  in  the  Journal  for  Feb 
1919,  p.  69. 


4i8 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  9 


supply  for  the  reversing  motor  is  supplied  by  a  flywheel 
motor-generator  set.  This  set  consists  of  two  direct- 
current  shunt  wound  generators  and  an  alter- 
nating-current wound  rotor  induction  motor,  rigidly 
coupled  to  the  shaft  of  a  flywheel  mounted  in  water- 
cooled  bearings  and  located  between  the  motor  and  one 
of  the  generators.  The  direct-current  system  is 
generally  600  or  700  volts  per  machine,  while  the  driv- 
ing motor  is  designed  to  suit  the  main  alternating-cur- 
rent supply  circuit  and  is  usually  either  2200  or  6600 
volts,  25  or  60  cycles.  The  exciter  set  consists  of 
an  induction  motor  driving  a  constant  potential  and 
a  variable  potential  generator.  The  variable  potential 
generator  has  its  field  circuit  in  series  with  the  main 
direct-current  armature  circuit  and  its  potential 
varies  with  the  motor  current,  supplying  a  field  to  the 
main  mill  motor  that  is  proportional  to  the  main  motor 
armature  current.  The  constant  potential  generator 
is  a  standard  exciter  and  supplies  excitation  for  the 
generator  shunt  fields  and  the  constant  potential  field 
of  the  main  mill  motor. 

Control — The  con- 
trol for  a  reversing  mill 
drive  is  also  shown  in 
Fig.  14  and  consists  of 
a  main  switchboard 
panel,  a  forward  and 
reverse  primary  circuit 
breaker,  a  liquid  slip 
regulator  for  the  con- 
trol of  the  motor  driv- 
ing the  flywheel  motor 
generator  set,  a  direct- 
current  tie  panel  be- 
tween the  main  mill 
motor  and  generator 
and  an  auxiliary  con- 
panel  and  starter 
for  the  exciter  set  and  the  blower  motor. 

The  reversing  motor  is  controlled  automatically 
by  magnetic  switches.  Adjustable  relays  control  the 
rate  of  acceleration  and  retardation  of  the  motor,  so 
that  it  operates  at  a  rate  consistent  with  the  reductions 
which  will  be  taken  in  the  mill.  The  control  is  so  in- 
terlocked that  the  motor  always  has  full  field  when 
starting.  Further  increase  in  speed  up  to  the  maxi- 
mum occurs  after  the  generator  field  has  obtained  full 
strength. 

PERFORMAXCE 

Electrically-driven  plate  mills  have  been  in  opera- 
tion in  this  country  since  1907.  The  motor  on  the  36 
inch  universal  plate  mill  of  the  Illinois  Steel  Company 
— the  first  reversing  mill  drive  installed  in  this  country 
— has  demonstrated  the  reliability  of  electric  drive,  as 
it  has  been  in  constant  operation  since  May  1907.  In 
its  thirteenth  year  of  operation  no  delays  were  charged 
against  the  electric  drive,  yet  that  year  the  mill  rolled 
the   maximum   tonnage   in   its   historj^   which   was   20 


FIG.     I.-? — DI.\GRAM     OF     CONNFXTIOXS 
FOR     .\     WOUND     ROTOR     MILL     MOTOR 

AND     LIQUID     SLIP    REGULATOR  trol 


percent  greater  than  that  rolled  during  any  of  the  first 
ten  years  of  its  operation.** 

'  The  reversing  equipment  on  the  two-high  rough- 
ing stand  of  the  84  inch  tandem  plate  mill  of  the  Brier 


JATtC  DIAGRAM 


Series  Transformer 


Reversing 

Constant 
Potaitio!  Field 


FIG.     14 — DIAGRAM    OF    CONNECTIONS    OF    DOUBLE    U.N  IT    REVERSING 
MILL    EQUIPMENT 

Hill  Steel  Company  operated  its  first  year  without  any 
delay  being  charged  against  it.  This  mill  holds  records 
for  the  number  of  slabs  rolled  per  hour,  per  day  and 
per  month,  as  well  as  the  thinness  of  gauge  for  the 
width  of  plate  rolled,  as  given  in  Fig.  15.  The  ability 
of  this  mill  to  roll  the  maximum  number  of  slabs  and 
thinness  of  g;auge  is  due  to  the  dispatch  with  which  the 


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FIG.    I.S — ROLLING   RECORDS  OF  THE  84   INCH   TANDEM   PLATE 
MILL  OF  THE  BRIER   HILL   STEEL  COMPANY 

ij  Hours  2j  Hours 

Number  of  slabs 1659 

Number  of  passes  in  roughinif  mill    7 

Total   charaed   weight-tons    ^"^ 

Total    finished    weight-tons    "^ 

Max.  Number  of  slabs  for  one  hour  220 

Finished  tons  of  10,  11,  12,  and  14  gauge  U.  S. 

standard    -^ 

Finished  tons  of  8  and  9  gauge 13 

Finished  tons  of  A  inch  No.   10  gauge   26 

Finished  tons  of   Vi.   inch  and  heavier  25,3 

The  large  tonnage  rolled  and  the  small  gauge  that  can 
be  finished  demonstrate  the  dispatch  with  which  the  steel 
is  handled  and  finished  before  it  looses  its  heat, 
slab  can  be  roughed  down  and  rolled  to  width  on  the 
reversing  roughing  mill  before  delivery  to  the  three- 
high  finishing  mill. 


3270 

716 


435 
6 
6 


■**  The  operating  record  ot  this  motor  is  given  in  an  article 
this  issue  by  Mr.  W.  S.  Hall  on  p.  400. 


September,  1921 


THE  ELECTRIC  JOURNAL 


419 


The  power  consumption  in  kilowatt-hours  per  ton 
of  plate  charged  weight  for  132  and  110  inch  three- 
high  plate  mills  is  shown  in  Fig.  16  and  that  of  a  90 
inch  and  an  84  inch  three-high  tandem  plate  mill  is 
shown  in  Fig.  17.     The  power  consumption  of  the  aux- 


sults  in  a  lower  obsolescence  charge  than  is  the  case  for 
any  steam  drive.  The  electric  motor  also  gives  a  maxi- 
mum and  uniform  turning  moment  in  any  position,  in- 
suring ease  and  smoothness  of  starting.  This,  as  well 
as  absence  of  reciprocating  parts,  results  in  less  wear 


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FIG.     16 — POWER    REQUIRED    FOR    DRIVING    PLATE    MILLS 

A — Main  drive  of  l.?2  inch  three  high  plate  mill ;  average 
kw  per  ton  :=2Q.2. 

B — .A.uxiliaries  for  i.?2  inch  three  high  plate  mill;  average 
kw  per  ton  =  22.8. 

C — Main  drive  for  no  inch  three  high  plate  mill:  average 
kw  per  ton  =22.2. 

The  dotted  line  indicates  that  the  mill  was  not  in  operation. 

ilianes  of  the  no  inch  mill  are  also  shown,  but  the 
other  curves  include  the  powei  consumed  by  the  mill 
only. 

The  efficiency  of  the  earliest  motors  driving  steel 
mills,  is  as  high  today  as  at  the  time  of  their  installa- 
tion. This  constant  efficiency,  which  is  high  even  at 
light  loads,  makes  the  electric  drive  highly  desirable, 
particularly  in  periods  of  business  depression,  and  re- 


FiG.    17 — Power  required  for  driving  plate  mills 
A — 00  inch  three  high  plate  mill ;   average  kw   per  ton  ^= 

ton  =  29.6. 

B — 84  inch  three  high  tandem  plate  mill ;  average  kw  per 

ton  =  28.8. 

and  breakage  in  the  driving  units  as  well  as  in  the  mill 
parts. 

It  is  an  accepted  fact  that  an  electrically-driven 
mill  produces  a  higher  tonnage  than  the  same  mill 
when  steam  driven.  This  is  due  to  the  fact  that  an 
electric  motor  maintains  a  higher  average  speed 
throughout  the  rolling  cycle  and  to  its  ability  to  absorb 
energ}'  from  and  restore  it  to  the  flywheel  rapidly. 
Production  is  further  increased  by  the  reduction  in 
number  and  length  of  mill  delavs. 


Power-Faetor  Correctloii  m  Sxeol  iVlills 


THE  NEED  of  power-factor  correction  is  evi- 
denced in  practically  every  steel  mill.  The 
general  characteristics  of  the  various  loads  in  a 
steel  mill  tend  to  produce  a  low  lagging  power-factor. 
The  general  characteristics  of  industrial  loads  have 
led  central  stations  to  discriminate  between  the 
loads  of  their  customers,  especially  with  reference  to 
power- factor ;  or  if  the  power  is  generated  locally,  low 
power-factor  increases  the  cost  of  generating  and 
transforming  equipment  to  an  appreciable  extent. 
Low  power-factors  have  a  much  greater  effect 
on  the  voltage  regulation  than  high  power-factors,  dae 
to  the  predominant  effect  of  the  reactive  drop,  which 
may  have  a  detrimental  effect  upon  the  performance 
of  the  connected  load.  And,  although  a  point  of  lesser 
importance  to  the  steel  mill  customer,  high  power-fac- 
tor increases  the  system  efficiency  from  generators  to 
load. 

The  balance  of  power  in  a  particular  steel  mill 
is  largely  dependent  upon  the  steel  processes  in- 
volved, but  can  be  controlled  to  some  extent  by  the 
application  engineer  in  the  layout  of  the  plant.  An 
analysis  of  a  well  balanced  plant  which  is  completely 


MOLLIS  K.  SELS 

General  Engineering  Dept. 
Westinghouse  Electric  &  Mfg.  Company 

electrified  will  bring  out  the  principal  items  of  the 
balance  of  power  and  the  relative  amounts  of  each 
as  shown  in  Table  I  and  shown  graphically  by  Fig.  i, 
omitting  the  furnaces,  which  indicates  that  the  average 
total  power-factor  may  range  from  85  to  95  percent 
for  such  a  plant.  As  the  relative  amounts  of  power 
vary  for  particular  installations,  the  power-factor  may 
be  correspondingly  higher  or  lower.  The  present  day 
tendency  has  been  to  improve  the  power-factor,  but,  in 
general,  the  characteristics  of  most  installations  have 
been  such  as  to  give  poorer  power-factor  than  neces- 
sary, whether  from  poor  layout,  poor  load  factor,  or 
simply  from  not  applying  the  necessary  corrective 
factors. 

Since  the  cost  of  generators,  transformers,  dis- 
tribution lines,  and  transmission  losses  and  the  regula- 
tion is  determined  by  the  kv-a  rating  rather  than  the 
kw  rating,  it  is  to  the  interest  of  both  the  consumer 
and  the  central  station  to  maintain  as  high  a  power- 
factor  as  will  prove  economical.  On  this  account  the 
central  stations,  in  their  contracts  with  large  power 
consumers,  have  in  recent  years  included  clauses  to 
the  effect  that  the  power-factor  must  be  maintained 


420 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  9 


above  a  certain  amount,  depending  upon  the  amount  of 
total  connected  load  or  maximum  demand.  For  other 
power-factors  the  customer  is  penalized  or  given  a 
premium  for  falling  below  or  above  this  set  amount. 
Probably  the  most  popular  rate  is  that  operating  on 
the  maximum  demand  rate  in  the  direct  ratio  of  the 
average  power-factor  of  the  load  to  the  power-factor 
set  by  the  central  station.  However,  some  companies 
do  not  adopt  such  a  sliding  scale,  but  fix  definite 
limits  of  power-factor  for  penalizing  or  paying 
premium.  In  either  case  the  tendency  for  the  central 
station  is  to  make  the  rates  attractive  enough  so  that 
the  consumer  will  see  to  his  own  corrective  apparatus. 
The  question  of  high  power-factor  is  of  nearly 
equal  importance  when  the  power  is  generated  locally. 
If  the  full  load  power-factor  is  high,  the  kv-a  rating  of 
the  generating  and  transforming  equipment  is  mate- 
rially reduced,  thereby  reducing  its  cost  proportion- 
ately.    At  light  loads  the  cost  of  keeping  units  on  the 

TABLE  I— BALANCE  OF  POWER 


Application 

Percent  of  Total  I.ond 

Avgr.P-F. 

Consumed 

Connected 

I — Electric   furnaces 

Special 

Special 

9S 

II — Direct-current  suddIv 

a — Synchronous 

converters 

b — Motor-genera- 

30 

IS 

100 

tor   sets,   which  are 

80  lead 

synchronous  above 

300  kilowatts 

/ 

III — .Auxiliary  Drive, 

which  inay  be  ei- 

ther synchronous 

or  induction  mo- 

tor 

16 

47 

100  or 
80-85 

IV — Main  roll  induction 

motor   drive 

SO 

33-5 

75 

V — Alternating-current 

lighting 

4 

4-5 

98 

regulation  at  full  load,  resulting  in  higher  stand-by 
losses  as  well  as  aggravating  the  poor  power-factor  at 
light  loads.  Transmission  losses  are  also  determined 
by  the  total  kv-a  load  and,  for  a  given  amount  of 
power,  will  be  considerably  higher  for  low  power-fac- 
tors. 


line  unloaded,  except  for  reactive  load,  is  high  and 
higher  power-factors  will  materially  reduce  these 
stai:d-by  losses. 

On  account  of  the  magnitude  of  the  reactive  drop, 
a  small  reactive  component  of  the  load  will  produce  as 
much  voltage  drop  as  will  the  power  component  of  the 
load  through  the  resistance  drop.  For  this  reason 
high  power-factor  is  important  from  a  regulation 
standpoint.  The  effects  of  poor  regulation  in  a  dis- 
tribution system  may  be  two  fold.  First,  in  the  per- 
formance of  the  connected  apparatus,  in  that  standard 
motor  equipment  is  not  guaranteed  for  more  than  ten 
percent  above  or  below  nonnal  voltage  and  for  a  con- 
stant current,  the  horse-power  output  varies  nearly  as 
the  square  of  the  impressed  voltage.  The  torque  is 
also  reduced  as  the  square  of  the  voltage.  Where 
alternating  current  is  used  for  lighting  purposes  the 
quality  of  the  illumination  is  greatly  affected,  due 
to  the  sensitivity  of  the  lamps  to  slight  voltage  varia- 
tions. Second,  the  transmission  losses  will  also  be 
higher  for  poorer  regulation,  and  transformers  will 
usually  be  operated  at  much  higher  induction  if  they 
are  being  operated  on  undervoltage  taps  to  improve  the 


KK;.      1 — VECTOR     D1.\GKAM 

Showing  possible  resultant  power-factors  with  loads  of 
different  power- factor,  corresponding  to  the  balance  of  power 
shown  in  Table  I. 

The  extent  to  which  power-factor  can  be  eco- 
nomically improved  should  be  based  on  an  extensive 
system  study.  Although  many  factors  effect  this 
phase  of  the  problem  it  is  possible  to  generalize  to 
some  extent.  For  this  purpose  two  particular  points 
will  be  considered ;  first,  assuming  that  there  are  no 
limitations  in  the  prime  mover,  the  amount  of  increased 
generator  capacity  which  will  be  obtained  on  a  con- 
stant kv-a  basis  corresponding  to  the  added  kv-a  cor- 
rective factor,  and  second,  on  a  constant  load  basis, 
the  reduced  cost  in  generator  and  transformer  equip- 


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jn;     2 EFFECT   OF   POWER-FACTOK    CORRECTION    ON    ADDITIONAL   GEN- 
ERATOR   CAPACITY    AND    RgSCLTANT    PO\VER-F.\CTOR 

With  a  constant  kv — a  load  of  100  percent, 
ment    and    the    reduction    in    losses    due    to    increased 
power-factor. 

The  curves  Fig.  2,  show  the  relation  between  the 
additional   generator   capacity  available,   corresponding 


September,  1921 


THE   ELECTRIC  JOURNAL 


421 


to  the  added  leading  kv-a,  expressed  in  percent  of  the 
original  load  on  the  basis  of  100  percent  kv-a,  and 
taking  into  account  the  losses  in  the  corrective  appara- 
tus. The  curves  illustrate  very  clearly  the  large 
amount  of  corrective  factor  required  in  comparison  to 
the  additional  generator  capacity  obtained  in   improv- 


100  Percent  of  Original  Load 


FIG.    \ — DIAGRAM    SHOWING    HOW    PERCENT   ADDITIONAL   GENE|,\TING 
CAPACITY    IS    OBTAINED    WITH    ADDED    CORRECTr\'E    KV-A 

All  in  percent  of  original  load  with  constant  kv-a. 
ing  the  power-factor  at  the  higher  power-factors. 
For  example,  to  increase  the  power-factor  from  90  to 
95  percent  requires  approximately  2.5  times  as  much 
corrective  kv-a  as  there  will  be  increase  in  generator 
capacity.  Fig.  3  shows  how  the  curves  in  Fig.  2  were 
derived.  All  vector  relations  have  been  expressed  in 
percent  of  the  original  kw  with  the  exception  of  the 
■total  kv-a  which  has  been  referred  to  as  100  percent 
kv-a  maintained  constant.  The  losses  of  the  corrective 
equipment  are  taken  into  account  by  subtracting  them 
from   the   additional   generator   capacity   available    for 


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FIG.  4 — EFFECT  OF  POWER-FACTOR  CORRECTION  ON  REDUCTION  IN  KV-A 
AND    RESULTANT    POWER-FACTOR 

With  a  constant  load  of  100  percent  kw. 
zero  loss  and  expressing  the  remainder  in  percent  of 
the  original  load. 

With   turbogenerator  units   costing  approximately 
three   times   as   much   as   synchronous   condensers  per 


kv-a  installed,  it  would  appear  that  it  would  be  eco- 
nomical to  correct  to  about  95  percent  power-factor. 
However,  since  the  turbogenerator  units  are  usually 
rated  at  80  to  90  percent  power-factor,  the  power- 
factor  could  not  be  corrected  above  these  values  with- 
out exceeding  the  capacity  of  the  turbines,  if  the  addi- 
tional generator  capacity  was  used.  By  this  same 
comparison,  other  means  of  improving  power-factor 
can  be  evaluated  against  the  cost  of  turbogenerator 
units  and  auxiliaries,  and  the  economical  point  on  the 
curves  determined  where  the  ratio  of  the  additional 
generator  capacity  to  the  capacity  of  the  corrective 
apparatus  is  equal  to  the  inverse  ratio  of  their  respec- 
tive costs.  This  point  will  never  reach  unity  power- 
factor  as  the  ratio  at  this  point  is  zero  making  the  re- 
quired ratio  of  costs  infinite.  It  must  be  remembered 
that  the  improvement  in  power-factor  will  mean  other 
attendent  benefits  in  improved  regulation  and  decreased 
losses  with  constant  kv-a  which,  if  evaluated,  may  make 
it  desirable  to  improve  the  power-factor  further.  The 
curves  also  indicate  very  clearly  the  effects  of  the  loss 
in  the  corrective  apparatus  in  reducing  the  increased 
generator    capacity     when     neglecting    the    decreased 


100  Percent  Kw  Constant  Load 


FIG. 


-DIAGRAM    SHOWING    HOW    PERCENT    REDUCTION    OF   ORIGINAL 
KV-A    IS    OBTAINED    WITH    ADDED    CORRECTIVE    KV-.\ 

All   in  percent  of  oris'inal   load,   which  is  constant  except 
for  the  additional  losses. 

losses  in  the  remainder  of  the  system,  and  show  that 
there  will  be  an  actual  loss  when  correcting  to  nearly 
unity  power-factor.  However,  on  account  of  the  re- 
duced losses  in  the  rest  of  the  system,  the  zero  loss 
curves  in  Fig.  2  may  be  the  most  correct. 

On  a  constant  kw  basis,  improved  power- factor 
will  reduce  the  kv-a  with  a  consequent  reduction  in  the 
losses  and  an  improvement  in  the  regulation.  The  re- 
duction in  kv-a  will  give  a  direct  saving  in  the  trans- 
former capacity  required  and  the  higher  power-factor 
will  permit  the  application  of  a  cheaper  generator. 
However,  since  the  kv-a  is  inversely  proportional  to 
the  power-factor  for  a  given  load,  there  will  not  be 
such  a  marked  saving  above  90  or  95  percent  power- 
factor  as  there  will  be  at  60  or  70  percent,  so  that  cor- 
rection above  these  values  is  probably  not  justified  for 
a  saving  in  kv-a  rating  alone.  Curves  similar  to  those 
in  Fig.  2  are  given  in  Fig.  4  which  illustrate  this  point. 
The  diagram  in  Fig.  5  shows  how  the  curves  in  Fig.  4 
were  derived.  All  vector  relations  have  been  ex- 
pressed in  percent  of  the  original  load,  which  has  been 
referred    to   as    100   percent   kw   maintained    constant. 


422 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  9 


The  losses  of  the  corrective  equipment  are  taken  into 
account  by  adding  them  to  the  load  and  increasing  the 


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1-lG.    0 — TYPICAL    I'OWEK-FAeiUK    AND    LUAU    CHARTS    IX    A    STEEL 
PLANT    HAVING     UNUSUALLY    GOOD    CHARACTERISTICS 

a — Kw  chart  of  dav  load  at  power  house. 

b — Power-factor  chart  corresponding  to  a. 

c — Kw  chart  of  woo  horse-power  continuous  bar  mill 
motor. 

d — Power-factor  chart  corresponding  to  c. 

e — Kw  chart  of  i6oo  hp  sheet  mill  motor. 

/ — Power-factor  chart  corresponding  to  c. 

g — Power-factor  chart  of  1500  kw  motor-generator  set 
at  power  house  with  leading  power-factor. 

/) — Power-factor  chart  of  two  500  hp  river  pump  mo- 
tors. 

i — Power-factor  chart  of  ,^00  hp  cold  roll  motor. 


resultant  kv-a  correspondingly,  which  decreases  the 
net  reduction  in  kv-a.  However,  since  the  losses  in  an 
extensive  system  may  be  reduced  sufficiently  to  over- 
balance any  additional  losses,  the  zero  loss  curves  in 
Fig.  4  may  be  the  most  correct. 

On  the  basis  of  eitlier  constant  kv-a  or  constant 
kw  the  capitalization  of  losses  should  be  taken  into  ac- 
count in  determining  the  economical  power-factors 
In  this  connection  there  are  two  factors  to  take  into 
consideration;  on  the  one  hand  there  are  the  additional 
losses  of  the  corrective  apparatus,  while  on  the  otlier 
there  is  the  reduction  in  the  generation  and  trans- 
inission  losses  which  tend  to  balance  out  at  low  power- 
factors  but  at  high  power-factors  do  not.  If  the 
power  is  generated  locally,  this  capitalization  in  con- 
nection with  the  cost  of  the  corrective  apparatus  and 
the  -evaluation  of  the  additional  generator  capacity 
available  or  the  reduction  in  the  generator  and  trans- 
former equipment  will  complete  the  study  for  the  eco- 


-100 

Win 

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FIG.    7 — IMPROVEMENT   OF    POWF.R-FACTOR    OBTjMNABLE    WITH    A 
PHASE     MODIFIER 

nomical  power-factor.  When  the  power  is  purchased 
from  a  central  station,  this  capitalization  in  connection 
with  the  cost  of  the  corrective  equipment  must  be  bal- 
anced against  the  reduction  in  rates  capitalized  in  a 
similar  way. 

The  first  and  most  obvious  method  to  be  con- 
sidered for  the  improvement  of  power-factor  is  in  the 
application  of  synchronous  motors  in  the  layout  of  the 
plant,  and  the  careful  application  of  induction  motors 
so  that  the  load  factor  will  be  good  and  the  powSr- 
factor  correspondingly  better.  The  charts.  Fig.  6, 
show  to  what  extent  this  means  has  been  carried  out 
in  one  plant.  It  will  be  seen  that  the  power-factor  on 
the  power  house  is  unusually  high,  although  the  other 
charts  of  the  principal  motor  installations  at  this  plant 
show  the  typical  power-factor  conditions  existing  in 
the  various  applications.  The  evident  solution  here  is 
in  the  application  of  a  synchronous  motor-generator 
set  operating  a  leading  power-factor. 

In  addition  to  the  application  of  synchronous  mo- 
tors to  motor-generator  sets  for  aiding  in  power-factor 
correction.  Table  I  shows  that  there  are  numerous  aux- 
iliaries about  a  large  steel  mill  that  may  be  driven  by 


September,  1921 


THE  ELECTRIC  JOURNAL 


423 


synchronous  motors.  A  synchronous  motor  may  be 
readily  designed  at  comparatively  little  additional  cost 
to  carry  the  same  reactive  kv-a  as  it  will  kw  load.  By 
the  application  of  a  constant  current  regulator,  syn- 
chronous motors  can  be  arranged  to  carry  their  maxi- 
mum continuous  rating  at  all  times,  so  that  at  light 
mechanical  loads  they  will  be  taking  practically  their 
full    capacity    at    leading   power-factor.     This    feature 


TABLE  II- 


A  COMPARISON  OF  SYNCHRONOUS  AND 

INDUCTION  MOTORS 


Synchronous   Motors 

Induction  Motors 

Auxiliary  Apparatus  Required                               | 

Autotransformers 

Autotransformers 

D-C  excitation 

No  excitation  required 

Field  rheostats 

No   rheostat  required  ex- 

Instruments   indicating   ad- 

cept with  wound  rotor 

justment  of  field  current 

motors 

Starting   friction   clutch   in 

No   instruments  required 

some  cases 

No  clutch  required 

Construction                                               | 

Stator 

Stator 

Rotating  field   structure 

Squirrel-cage    winding   or 

with  definite  poles 

wound  rotor 

Collector   rings   and  brushes 

No  brushes  except  on 

wound  rotor  motors 

Starting-                                                   | 

Starting  operations — 

Starting  operations — 

Short-circuit  field 

Close   starting  switch 

Close  starting  switch 

Change  from  starting  to 

Apply  excitation 

running  position 

Change  from  starting  to 

running  position 

On  some  basis   starting 

Full-load    starting   torque 

torque    is    usually    some- 

on squirrel-cage  and 

what   less    than    induction 

twice   full   load  on  wound 

motors   with  pull   in 

rotor  motors 

torque  about  50  percent 

of  full  load 

Self  starting 

Self  starting 

Runn 

mg 

Constant  speed  with  fixed 

Constant   or  variable   speed 

relation  to  generator 

with  elastic  relation  to 

Maximum   torque  at   syn- 

generator 

chronous  speed 

Maximum  torque  usually 

Subject  to  hunting 

greater  than   synchronous 

Power-factor  can  be  con- 

motor  but   at   reduced 

trolled  with  excitation 

speed 

within  design  of  machine 

No  tendency  to  hunt 

and  when  set  at  full 

No  control  over  power-fac- 

load for  unity  or  leading 

tor,   which  is  always  lag- 

power-factor,   leading 

ging  and  low  for  light 

current    increased    as  load 

loads  and  slow  speed  mo- 

decreases 

tors 

On  short-circuit  acts  as  a 

Xo  generator  action  on 

generator 

short-circuit    except    dur- 

More sensitive  to  abnormal 

ing  transient  state 

conditions   than   induction 

Less  liable  to  trouble  under 

motor 

abnormal  conditions 

would  only  prove  economical  on  the  larger  installa- 
tions, such  as  a  large  motor-generator  set.  The  inher- 
ent characteristics  of  a  synchronous  motor  make  it 
suitable  for  driving  fans,  pumps,  compressors  and 
other  constant  speed  loads.  A  comparison  of  syn- 
chronous and  induction  motors  is  summarized  in 
Table  II. 

Since  the  balance  of  power  in  some  particular  in- 
stallations would  not  permit  suitable  application  of 
synchronous    motors    which    would    take    care    of    the 


power-factor  correction,  it  may  be  necessary  to  employ 
other  means  of  doing  this.  Also  the  layout  of  the 
plant  may  be  such  that  the  balance  of  power  giving  a 
suitable  power-factor  on  the  generator  would  not  bene- 
fit the  distribution  system  to  the  same  extent.  The 
ideal  conditions  for  power-factor  correction  in  order 
to  obtain  the  maximum  benefits  would  be  to  correct 
each  individual  load  to  unity  power-factor.  However, 
while  possible,  this  would  be  very  expensive  in  a  large 
plant  and  totally  unwarranted,  in  that  it  would  require 
all  loads  either  to  have  unity  power-factor  character- 
istics or  be  corrected  to  unity  by  phase-modifiers  on 
induction  motors,  static  condensers,  or  small  synchron- 
ous condensers. 

The  use  of  the  phase  modifier  has  not  been  ad- 
vanced in  this  country  to  the  same  extent  as  in 
Europe,  where  they  have  been  used  for  some  time. 
This  has  probably  been  due  to  the  lack  of  attention  to 
power-factor  correction  and  the  fact  that  the  system 
is  only  applicable  to  wound-rotor  motors  with  slight 
modifications  in  the  control.  However,  it  appears  that 
the  scheme  has  certain  advantages,  since  the  auxiliary 
machine  is  small  and  the  useful  capacity  of  the  main 
motor  is  materially  increased.  For  example,  to  raise 
the  power-factor  of  a  1000  kv-a  motor,  having  a  three 
percent  slip,  from  85  to  100  percent  power-factor  will 
require  a  phase-modifier  having  a  capacity  of  approxi- 
mately 16  kv-a,  for  which  a  three-fourths  horse-power 
motor  would  supply  the  losses.  This  will  give  an  in- 
crease in  the  main  motor  capacity  of  over  17  percent, 
against  which  the  increased  cost  of  the  motor  due  to 
the  rotor  winding  and  the  cost  of  the  modifier  would 
have  to  be  charged.  The  curves  in  Fig.  7  give  a  com- 
parison of  the  power-factor  of  a  motor  with  and  with- 
out a  phase  modifier.  By  running  the  phase  modifier 
at  a  higher  speed  the  power  factor  can  be  made  lead- 
ing. This  fact  would  be  useful  in  the  application  of  a 
!single  large  motor  in  a  small  isolated  plant  to  correct 
■  for  the  power-factors  of  a  number  of  small  motors. 

While  the  phase  modifier  is  no  doubt  competitive 
with  static  condensers,  it  is  doubtful  whether  either 
method  can  be  justified  except  in  relatively  small  iso- 
lated cases.  In  small  capacities  the  static  condenser 
represents  a  low  initial  investment,  is  very  efficient  and 
simple  in  operation,  but  has  the  disadvantage  of  a  fixed 
corrective  capacity  at  only  leading  power-factor  and 
of  requiring  a  great  deal  of  floor  space.  Also  the  char- 
acteristics of  a  static  condenser  are  such  as  to  aggra- 
vate the  disturbances  due  to  high  frequency  voltages 
impressed  on  the  condenser  and  for  the  same  reason 
will  produce  a  certain  amount  of  surging  in  the  line 
when  switched  on  and  off.  This  subjects  other  equip- 
ment to  unnecessary  high-frequency  disturbances  and 
additional  stresses  which  are  undesirable. 

Where  the  reactive  kv-a  to  be  supplied  is  of  the 
order  of  1000  kv-a  the  synchronous  condenser  installa- 
tion will  become  the  most  economical.  In  practically 
every  steel  mill  of  any  size  the  amount  of  leading  kv-a 


424 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  9 


required  will  exceed  this  and  will,  therefore,  be  in  ex- 
cess of  the  economical  application  of  either  static  con- 
densers or  phase  modifiers  and,  since  it  will  be  more  or 
less  concentrated  at  one  point,  can  be  taken  care  of 
more  economically  in  the  larger  blocks  by  a  synchron- 
ous condenser.  The  operation  of  a  condenser  can  be 
made  entirely  automatic  so  as  to  maintain  the  power- 
factor  or  voltage  above  a  predetermined  minimum. 
With  automatic  control  no  attendant  will  be  required 
and  only  a  weekly  inspection  is  necessary.  All  the 
contingencies  that  might  be  met  with  hand  operation 
are  provided  for,  with  the  result  that  the  machine  is 
better  protected  than  with  an  attendant  and  at  a  lower 
overall  cost.  Constant  voltage  can  also  be  maintained 
at  the  receiver  by  the  use  of  a  voltage  regulator. 

Since  the  power-factor  question   is  of  paramount 
importance  to  both  steel  mill  and  central  station  engi- 


neers, it  is  to  their  mutual  interest  to  consider  the  best 
means  of  improving  system  conditions  with  higher 
power-factor.  The  former  can  do  much  through  the 
studied  application  of  synchronous  motors  throughout 
the  plant,  either  to  improve  the  conditions  in  his  own 
plant  or  to  benefit  by  the  reduction  in  rates  which  the 
latter  should  make  available,  considering  the  mutual 
benefits  obtained.  In  this,  both  can  be  aided  to  a  great 
extent  by  the  broad  e.xperience  of  electrical  manufac- 
turers in  dealing  with  such  problems.  In  conclusion 
it  should  be  emphasized  that  the  economies  produced 
by  improving  power-factor  to  as  high  as  90  or  95  per- 
cent, and  in  particular  cases,  where  additional  correc- 
tion can  be  obtained  at  slight  cost  or  increased  size 
of  units  because  of  correcting  for  very  low  power  fac- 
tors, even  higher  percent  power-factors  are  well  worth 
considering. 


r- 

— 

EAELWAY  ©FJ^MATM^  ©ATA 

The    purpoae    of    thii    tection    la    to    preaent         The   cc- operation   of  all    those   interested    In 
accepted  practical  methoda  used  bj  operating          operating  and  maintaining  railway  equipment 
companies    throuchout    the    country                         is    invited.      Address    R.    0.    D.    Editor. 

- 

THE 
ELECTRIC 
JOURNAL 

SEPTEMBER 
1921 

— 

— 

- 

The  Assembly  of  Complete  Sets  of  Commutator  Segments 


With  railway  motors  ODeratine  under  modern  conditions, 
using  slotted  commutators  and  high-grade  graphitized  carbon 
brushes,  the  wear  on  the  commutators  has  been  greatly  re- 
duced, resulting  in  a  marked  increase  in  their  life.  This  is 
especially  noticeable  with  the  commutating-polc  motor.  Com- 
mutators on  some  large  railway  motors  of  the  commutating- 
Dole  tvoe  have  operated  for  twelve  years  without  rcauiring 
turnine.    and    show    practically   no    wear,    indicating    that    pro- 


FIG.    I — CHECKING    THE   TEMPERATURE   OF   THE   C0MMUT.-\T0R    WITH 
A    PYROMETER    BEFORE    PRESSING 

bablv  they  will  outlive  the  rest  of  the  armature.  However, 
such  a  case  is  the  exceotion  rather  than  the  rule,  as  the  com- 
mutators on  most  railway  motors  will  have  to  be  replaced  at 
least  two  or  three  times,  depending  upon  the  type  and  the 
service  conditions,  during  the  life  of  the  armature. 

SELECTION  or  MATEBIAL  FOB  COMMUTATORS 


I — Use  a  good  grade  of  hard  drawn  copper. 

2 — The  bars  should  be  carefully  straightened  and  all 
fins  and  burrs  removed,  after  which  they  should  be 
thoroughly  cleaned. 

.1 — Castings  should  be  clean  and  free  from  blow  holes 
and  all  defects.  They  should  be  made  of  such  materials 
as  to  give  the  desired  strength. 

4 — The  castings  should  be  accurately  machined  and 
checked  with  gauges  to  insure  interchangeability  and  to 
provide  a  snug  fit  for  the  built  up  insulation. 

5 — The  mica  segments  and  V  rings  should  be  built 
UB  from  a  carefully  selecti-d  grade  of  mica  held  together 
with  the  proper  bond  (to  prevent  slipping  when  assem- 
bled) and  baked  under  a  heavy  pressure. 

6 — The  mica  parts  should  be  carefully  machiiud  with 
minimum  tolerances  to  meet  the  required  dimensions  fot 
the  correct  building  up  of  the  assembled  commutator. 

COMMUTATOR   CONSTRUCTION 
The   following  tabulation  shows  tlie  various  types  of  con- 
struction,   the    detail    parts   and    the    material    that    enters   into 
the  make  up  of  the  commutators. 


1  \'  hound 


rHard  dra 
{     copper 


i   I'laiii  bars 
)  Sawed  bars 
1    1-michcd  bar 
t  Fiiiishec 


( Cast  iron 
binKS  S  Malleable  iron 

I  Cast  steel 

fCa.st  iron 
,,,  \-  i  Malleable  iron 

(Cast  steel 

'  RinK  nut  —  Hot  rolled  steel 

\  Bolts  —  Hut  rolled  steel 


METHOD  OF  ASSEMBLING 

When    a    complete    set    of    assembled    scgriients    is    to    be 


Some  of  the  more  impoi 


manufacture  of  commutators  are  as  follows: — • 


itant  points  to  be  considered  in  the      mounted  on  a  railway  armature  it  is  worth  while  to  pay  con 
-    -  siderable  attention  to   a  number  of   small   details   in  order  to 


September,  1921 


THE   ELECTRIC  JOURNAL 


425 


make  a  good  tight  job.  The  following  is  an  outline  of  a 
method  of  doing  this  work  which  has  given  very  good  results. 
The  onerations  are  eiven  in  the  order  in  which  thev  should 
be  followed. 

I — Fit  the  front  metal  V  ring  over  the  metal  bush- 
inET  or  snider.  It  mav  be  necessary  to  do  some  filling  to 
obtain  the  proper  clearance. 

2 — Fit  the  rine  nut  on  the  bushing.  It  mav  be  neces- 
sary to  clean  out  the  threads  on  the  bushing  and  nnt  to 
allow  the  nut  to  be  screwed  up  by  hand. 

3 — With  the  front  V  ring  placed  over  the  bushing  and 
the  ring  nut  screwed  up  tight,  check  the  clearance  of  the 


2 — FINAL    TIGHTENING    OF    C0MMUT-\T0R    WHILE    HOT    .\ND    UN- 
DER   PRESSURE 

front  V  rine  over  the  nut  by  lifting  it  up  against  the  un- 
der side  of  the  nut. 

4 — If  it  is  a  bolted  type  of  commutator,  the  same 
procedure  as  indicated  above  should  be  followed  with  the 
bolts,  etc. 


.S — Dismantle  the  metal  parts  and  scrape  off  all  the 
paint  and  dirt.     This  applies  especially  to  the  Vs. 

6 — Clean  out  the  Vs  in  the  assembled  copper  segments, 
using  fine  saneJ  paper.  Thoroughly  blow  out  all  dust  and 
dirt  and  checjc  for  short-circuits,  using  .soo  volts  between 
bars,  .\ftcr  testing,  brush  the  inside  of  the  Vs  with  a 
very  thin  coat  of  clean  shellac. 

7 — Thoroughly  clean  the  mica  V  rings  especially  at 
the  fit  of  the  V,  using  fine  sand  paper. 

8 — Assemble  all  parts  and  draw  up  the  ring  nut  as 
tight  as  possible  while  cold. 

g — Cut  ofif  the  temporary  band  wires  holding  the  seg- 
ments together  and  further  tighten  up  the  ring  nut. 

10 — Check  for  the  alignment  of  the  center  line  of 
commutator  bar  or  mica  (as  given  on  commutator  draw- 
ing) with  respect  to  the  center  line  of  the  keyway  in  the 
bushinff. 

1 1 — Heat  the  commutator  to  a  temperature  of  from 
12=;  to  lio  degrees  C.  and  press  while  hot  at  from  20  to 
.^o  tons,  depending  upon  its  size. 

12 — While  hot  and  under  pressure  further  tighten 
up  on  the  ring  nut,  after  which  remove  the  assembled 
commutator   from  the  nress  to  cool. 

13 — When  cold,  check  for  short-circuits,  using  500 
volts  beween  bars. 

14 — Check  for  grounds,  using  a  voltage  of  4000  volts 
alternating  current 

I  ^ — Press  onto  the  armature  spider  or  shaft  and  true 
up  the  face  and  neck. 

16 — After  soldering,  under  cut  the  mica  approximately 
3-64  inch  deep. 

NOTE  CAEEFULLY  THE  FOLLOWING  POINTS. 

I — Use  a  good  relialjle  make  of  mica  insulation.  Some 
grades  look  good  on  the  surface,  but  are  built  up  with 
an  inferior  bond  which  allows  the  pieces  of  mica  to  squeeze 
out  under  pressure.  With  this  grade  of  built  up  mica  it 
is  often  imiiossible  to  use  these  parts  a  second  time. 

2 — Tighten  the  conimutator  while  hot  and  under  pres- 
sure. 

:\ — If  an  oven  is  not  available,  it  is  preferable  to  heat 
the  assembled  commutator  on  the  outside,  using  a  gas  ring, 
rather  than  on  the  inside. 

4 — In  tightening  the  ring  nut  use  a  wrench,  rather  than 
a  hammer  and  chisel  which  destroys  the  nut. 

>; — If  for  any  reason  the  commutator  segments  have 
to  be  removed  after  the  bands  are  cut.  a  three  part  clamp- 
ine  rine  can  be  used  to  advantage  to  hold  them  together. 

John  S.  De.\n 


Our  subscribers  are  invited  to  use  this  department  as  a 
means  of  securing  authentic  information  on  electrical  and 
mechanical  subjects.  Questions  concerning  general  engineer- 
ing theory  or  practice  and  questions  regarding  apparatus  or 
materials  desired  for  particular  ne:ds  will  be  answered. 
Specific  data  regarding  design  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self  addressed  stamped  en- 
velope should  accompany  each  query  All  dat^  necessary  for 
a  complete  underst..nding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
as  the  necessary  information  is  available;  however,  as  each 
queston  is  answered  by  an  expert  and  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


2032 — Ch.\rging  Stor.\ge  Batteries — 
I  wish  to  install  a  charging  outfit  for 
automabile  storage  batteries,  starting 
and  lighting  (6  to  12  volts).  Which 
would  you  recommend,  a  motor-gen- 
erator set  or  a  rectifier? 

J.  G.  M.  (cold.) 
Either  a  motor-generator  set  or  a  rec- 
tifier would  be  suitable  for  charging  au- 
tomobile storage  batteries.  The  motor- 
generator  set  will  probably  cost  two 
or  three  times  as  much  as  the  rectifier 
with  the  same  capacity,  although  it  is 
somewhat  more  reliable  and  requires 
practically  no  upkeep  or  replacements. 
The  hot  cathode  type  of  rectifier  is 
simple  in  operation  but  it  is  necessary 
to  replace  the  bulbs  about  every  three 
months  if  used  continuously.  The  power 
required  to  operate  the  rectifier  is 
slightly  less  than  required  for  the  motor- 
generator  set  with  the  same  charging 
current.     With  the  motor-generator  set 


it  is  more  convenient  to  regulate  the 
charging  current  to  the  battery  as  a 
hand  operated  rheostat  is  usually  pro- 
vided for  this  purpose.  C.  H.  K. 

2033 — Magnetizing  Current  of  Induc- 
tion Motors — Have  noticed  on  small 
induction  motors  that  by  applying 
double  rated  voltage  to  the  stator, 
the  magnetizing  current  is  high,  due 
to  high  saturation,  but  as  the  load  is 
applied,  the  current  decreases.  Why 
is   this? 

A.    M.    M.    (COLO.) 

The  phenomenon  described  is  one 
which  occurs  very  rarely  in  induction 
motors  and  then  only  when  the  iron  is 
highly  saturated  and  the  impedance  of 
the  winding  is  high.  Wlien  the  mag- 
netizing current  of  a  motor  is  large  and 
there  is  no  load  on  the  motor,  the  im- 
pedance drop  is  out  of  phase  with  the 
generated  voltage.     That  is  it  does  not 


add  directly  to  it,  but  adds  vectorially  at 
an  angle.  When  a  load  is  put  on  the 
motor  this  angle  will  be  changed  and  a 
critical  point  may  be  reached  where 
the  impedance  drop,  although  its  value 
may  be  less,  is  in  phase  with  the  gen- 
erated voltage  and  will,  therefore,  cause 
it  to  be  lower.  This  means  a  lower  flux 
density  w-ith  a  lower  magnetizing  cur- 
rent. Since  the  current  is  composed 
mostly  of  the  magnetizing  component, 
the  resultant  current  may  be  less  even 
with  a  load  component  added  to  it.  This 
change  is  usually  small  and  occurs  at 
very  light  loads.  With  larger  loads  the 
current  will  increase.  L.  G.  T. 

2034 — Rewinding  Small  Transformers 
— Does  it  usually  pay  to  have  small 
transformers  from  5  to  7.5  kw  re- 
wound? w.  L.  B.  (que.) 
Assuming  the  current  net  price  com- 
plete  of   a  new   equivalent   transformer 


426 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  9 


as  I,  the  relative  costs  of  repairs  for  5 
kv-a  and  7.5  kv-a  transformers  will  be 
somewhat  as  follows  :■ — • 


Repair    uc 
Dune  In 
Custonie 

rk 

Rei.i.it   Work 
Done  by 
Factor\- 

N    — ^  e  V  c. 

l^!;l; 

0  5t 

0S2 

.Vet -New  .  oi 
insulatic 

s  will 
ti  and 

0.S5 

O.QO 

It  will  usually  be  found  unsatisfactory 
to  reassemble  coils  with  old  iron,  as  the 
impregnating  compound  adhering  to 
the  punchings  will  decrease  the  space 
factor  of  the  reassembled  iron,  and  cause 
abnormal  iron  losses.  This  trouble  can 
be  overcome  if  facilities  are  available 
for  reannealing  the  iron,  as  this  burns 
off  the  compound.  It  will  usually  be 
found  more  economical,  especially  with 
small  sizes,  to  have  necessary  repairs 
made  at  service  stations,  or  purchase 
new  coils  and  iron.  e.  p.  w. 

203s — ^Caubratinc  Alternating-  Cur- 
rent Meters — Can  a  potentiometer  be 
used  to  calibrate  alternating-current 
apparatus?     If   so   how   should   it   be 

used?  A.    A.    (MEXICO) 

A  potentiometer  can  be  used  to  cali- 
brate alternating  -  current  apparatus 
which  will  operate  with  accuracy  on 
direct  current,  since  the  potentiometer 
is  for  use  on  direct  current  only.  Volt- 
meters are  connected  in  parallel  with  the 
potentiometer  and  sufficient  voltage  ap- 
plied, according  to  the  range  of  the  in- 
strument. If  a  higher  voltage  is  re- 
quired, above  1.5  volts,  a  volt-box  should 
be  connected  between  the  voltmeter  and 
the  potentiometer.  Ammeters  are  con- 
nected in  scries  with  a  standard  shunt, 
and  the  potential  leads  of  the  shunt 
connected  to  the  potentiometer.  The 
shunt  should  be  of  sufficient  resistance 
to  obtain  approximately  full  scale  read- 
ing on  the  potentiometer.  Two  poten- 
tiometers are  required  for  calibration 
of  wattmeters,  and  the  method  is  the 
same  as  for  ammeters  and  voltmeters, 
w.   J.    H. 

2036 — Operating  22000/2300  Volt,  60 
Cycle  Transformer  on  toooo  Volts, 
50  Cycles — If  an  old  1500  kv-a  shell 
type  transformer  22000/2300  volts,  60 
cycles,  is  worked  at  loooo  volts,  50 
cycles  will  the  effective  ratio  increase 
somewhat  due  to  the  increase  in  flux 
density?  In  what  proportion  will  the 
exciting  current  increase?  Will  the 
reactance  and  impedance  be  less  when 
the  transformer  is  worked  at  50  cy- 
cles? Will  the  temperature  also  in- 
crease due  to  the  increase  in  flux  den- 
sity? A.  A.   (MEXICO) 

Assuming  that  the  high  voltage  wind- 
ing can  be  connected  in  parallel  for 
1 1000  volts,  and  loooo  volts.  50  cycles  is 
impressed  on  this  winding,  the  flux  den- 
sity will  be  increased  in  the  ratio : 
10  000         60 

X =  1 .09 

II 000         50 
The  voltage   ratio   will   be   the   same   as 
at  60  cycles,  namely, 

loooo  II 000 


2090  2  300 

Without  knowing  the  particular  design 
of  this  transformer  it  is  not  possible  to 
state  the  inrease  in  exciting  current,  but 
with  nine  percent  increased  flux  density 


at  50  cycles  the  exciting  current  is  lia- 
ble to  be  more  than  double  of  what  it 
w'as  at  60  cycles.  For  the  same  kv-a 
output  the  reactance  will  be  changed  in 
the  ratio ; 

50      /  II  000\  - 
X  I  I  =  i.oi 

60  Vioooo/ 
For  the  same  kv-a  output,  the  tempera- 
ture of  the  iron  will  increase  due  to  the 
increased  flux  density  and  the  tempera- 
ture of  the  winding  will  increase  due  to 
the  increased  load  currents.  This  in- 
crease may  be  partly  counterbalanced  by 
the  decrease  in  eddy  current  loss.      h.  f. 

2638 — Starting  Current  of  a  Squirrel- 
Cace  Motor — •  A  2200  volt,  35  ampere 
per  terminal,  150  hp,  three-phase 
squirrel-cage  motor  drives  a  di- 
rect -  current  generator.  The  mo- 
tor is  started  with  a  compen  - 
sator.  What  starting  current  (ap- 
proximately) may  be  assijmed  be- 
tween the  oil  circuit  breaker  and  the 
compensator  and  between  the  com- 
pensator and  the  motor?  When  the 
statement  is  made  that  the  starting 
current  of  a  motor  is  2.5  times  full- 
load  current  when  used  with  a  com- 
pensator, what  current  is  referred  to, 
the  motor  current  or  the  line  current  ? 
Would  it  conform  to  the  Underwrit- 
er's requirements  to  run  a  smaller  wire 
between  the  line  and  compensator  and 
a  larger  wire  between  compensator 
and  motor,  the  circuit  breaker  being 
set  to  protect  the  smaller  wire  and 
the  larger  wire  being  as  many  times 
larger  as  the  current  to  the  motor  is 
larger  than  the  current  ahead  of  the 
compensator?  a.  u  j.  (pa.) 

A  motor  similar  to  this  one  will  have 
approximately  300  amperes  per  terminal 
with  full  voltage  applied  at  the  instant 
of  start.  This  current  will  vary  in  di- 
rect proportion  to  the  voltage  applied, 
i.  e.,  if  one-half  voltage  is  applied  to  the 
motor,  the  current  in  the.  motor  circuit 
will  be  150  amperes.  The  current  taken 
from  the  line  will  vary  directly  with 
the  square  of  the  voltage  applied  to  the 
motor,  i.  e.,  at  one-half  voltage  the  line 
current  will  be  75  amperes.  The  state- 
ment "2.5  times  full-load  current  when 
used  with  a  compensator"  considers  the 
motor  and  compensator  as  a  unit  and 
means  the  line  current.  Rule  8,  Page  19, 
of  the  llnderwriter's  rules  seems  to  us 
to  show  that  the  wire  between  line  and 
compensator  should  be  large  enough  for 
no  percent  of  full-load  current  and  the 
wire  from  compensator  to  motor  should 
be  large  enough  for  at  least  200  percent 
of  full-load  current.  c.  w.  k. 

2039 — microlambert — The  term  "micro- 
lamhert"  is  used  as  a  measure  of  lum- 
inosity in  connection  with  specifica- 
tions for  radium  paint,  such  as  used  on 
clock  dials  and  electric  push  buttons, 
etc.  I  would  like  to  know  the  quantita- 
tive meaning  of  the  word.  For  inst- 
ance, if  a  certain  paint  gives  six  micro- 
lamberts  and  some  time  later  gives 
three  microlamberts,  how  am  I  to 
judge  the  relative  luminosity?  Is  it  a 
unit  for  measuring  small  quantities  of 
light  or  a  measure  of  radio  activity?  Is 
there  any  conversion  factor  to  change 
microlamberts  to  lumens  or  foot  can- 
dles, w.  L.  D.  (pa.) 
The  lambert  is  the  c  g.  s.  unit  of 
brightness,  the  brightness  of  a  perfectly 
diffusing  surface  radiating  or  reflecting 
one   lumen   per   square   centimeter.   The 


millilambert  or  o.ooi  lambert  is,  for  most 
purposes,  the  preferable  practical  unit. 
A  perfect  diffusing  surface  emitting  one 
lumen  per  square  foot  will  have  a  bright- 
ness of  1.076  millilambcrts.  Brightness 
expressed  in  candles  per  square  centi- 
meters may  be  reduced  to  lambcrts  hy 
multiplying  by  3.1416.  Brightness  ex- 
pressed in  candles  per  square  inch  may 
be  reduced  to  foot  candle  brightness  by 
multiplying  by  I44ir=452,  Brightness  ex- 
pressed in  candles  per  sq.  inch  may  be 
reduced  to  lamberts  by  multiplying  by 
T/645     =     o..|868.     A     microlamberts 


■  lambert. 


2040 — transformer  secondary  equival- 
ent resistance — The  test  data  of  a 
2000  kv-a  self  cooled  50  cycle,  67  500 
Y/20  600  Y  volts,  17.1/56.1  amps 
transformer  are: —  Resistance  mea- 
surements at  23  degrees  C.  on  each 
phase  to  neutral  average :  high  tension 
5.76  ohms;  low  tension  0-599  ohms. 
Impedance  tests  made  with  the  high 
tension  winding  short-circuited  showed 
the  following  impedance  to  neutral, 
low  tension : — ^^7,03  ohms,  S=:6.8 
ohms,  C^7.03  ohms  ,  avcrage=6.95 
ohms ;  reactance  calculated  from  the 
forcgoing^6.86  ohms.  Resistance  cal- 
culated as  low-tension  equivalcnt= 
1. 137  ohms.  Ratio  by  test  using  poten- 
tial transformer  on  primary=:3.i9- 
Kindly  explain  how  to  obtain  the  equi- 
valent low-tension  resistance.  Does  the 

formula   R=::iiR.   given   in   Sheldon's 

.Alternating-Current  Text  Book,  page 
164,  apply  in  this  case? 

a.  a.  (Mexico) 

The  value  of  low  tension  resistance 
given  as  Q.599  ohms  should  probably  be 
0.9599  ohms.  Assuming  this  to  be  correct 
the  equivalent  low-voltage  resistance  on 
one  phase  may  be  calculated  from  the 
following  formula: — 
„     „      .  /Ei-t\-^  /20.6oo\- 

X  5.76=1.498  ohms. 

This  is  different  from  Sheldon's  equa- 
tion (p.  165)  in  that  it  gives  the  equival- 
ent resistance  of  the  whole  transformer 
in  terms  of  the  low-tension  winding, 
while  Sheldon's  equation  gives  the  resist- 
ance of  the  high-tension  winding  only  in 
terms  of  the  low  tension.  h.  f. 

2041 — EROSION    OF    STEAM    TUKIM.NE    HIAPES 

— In  a  reaction  type  steam  turbine 
what  causes  the  three  of  four  rows  of 
blading  on  the  exhaust  end  to  be 
honeycombed,  cut  or  eroded,  all  other 
blading  showing  no  signs  of  erosion. 
The  steam  is  quite  dirty  and  doubtless 
wet.  yet  the  cutting  is  on  the  last  rows 
onlv.  An  impulse  turbine,  under  similar 
conditions,  shows  erosion  on  the  first 
row  of  buckets  where  the  steam 
strikes. 

D.  c.  M.  (WYO.) 

In  general  this  action  is  due  to  the 
higher  blade  velocity  and  higher  steam 
velocitv  employed  in  the  low  pressure 
stages,'  together  with  the  higher  percent- 
age of  moisture  contained  in  the_  steam 
at  this  point.  This  erosive  action,  is  very 
slight  when  corrosive  agents  areabsent; 
the  latter,  however,  are  present  in  vary- 
ing quality  and  quantity  in  most  installa- 
tions. 

R.  E.  C. 


/^2  7 


The  Electric  Journal 


Vol.  xviii 


October.  1921 


No.  lO 


T 


Drive  Home  the  Facts 

p.  H   GADSDEN 

President, 
American  Electric  Railway  Association 

HE    frequently    predicted    crash    in    the    electric 
railway    field,    due    to    lawless    competition    and 


It  is  up  to  every  man  in  the  industry  to  see  that 
everyone,  who  uses  street  cars  and  is  dependent  upon 
them  in  whole  or  in  part  for  financial  success,  is  sup- 
plied with  this  same  knowledge  of  what  it  means  to 
be  without  electric  traction  service.  It  is  unbelievable 
that  the  car  riders  and  the  business  men  of  any  pro- 
public  non-support  of  adequate  fares,  has  come  gressive  city  in  this  country  today  would  willingly  place 
recently  in  several  parts  of  the  country.  Notable  ex-  themselves  in  the  position  of  the  car  riders  and  busi- 
amples   are    found   in   Des    Moines,    Iowa;    Bay    City,      ness  men  of  Des  Moines,  if  they  knew  the  truth.     We 

must  make  them  realize  that 
what  has  happened  in  Des 
Moines  inevitably  will  hap- 
pen elsewhere  if  electric 
railways  are  not  gi\en  the 
proper  support. 

To  bring  this  message  to 
the  attention  of  the  general 
public  is  no  easy  task,  but 
every  management  can  and 
should  do  it.  It  cannot  be 
done  by  writing  a  few  letters 
or  issuing  a  few  statements 
to  the  press  but  it  can  be  ac- 
complished by  using  eveiy 
available  publicity  channel 
nt  our  command.  Let  yon:- 
people  know  the  truth  and 
the  truth  will  set  vou  free. 
The  facts  about  these 
street-car-Iess-cities  are  un- 
questioned, and  when  ^'ou 
can  bring  the  situation  home 
to  your  own  people,  it  can- 
not help  but  impress  them. 

The    American    Electric 
Railway  Association  is  anxi- 
ous   to    help    ever}'    electric 
railway    manager    to    tell  his 
people  this    story    of    service 
abandonment   and  the   result 
on    comfort    and    prosperity. 
Articles     and      leaflets      for 
general    distribution    are    be- 
ing prepared  and  will  be    sent    out.        And    the   Asso- 
ciation will  do  more.     If  you  will  communicate  with 
our    executive     offices,     it     will     suggest     ways     and 
means    by     which    you    can    carry    the    story     farther 
than  it  can    be    carried    by    mere    printed    advertising 
matter. 


Saginaw     and      Manistee 

Michigan.       It    is     shameful 

that    these    collapses    had    to 

occur,  but  out  of  them  even- 
tually will    come  great    good 

to  the  entire    industry.      The 

reason  is  that  these   failures 

will  drive  home  through  the 

tired  feet  of  the   former  car 

rider      and      the      shrinking 

pocket-book   of   the   business 

man,    the    inescapable    truth 

that     electric     railways     are 

vital     to     the     comfort     and 

prosperity    of    ever}-    city    in 

the  land.     The  lesson  w-ill  be 

a   severe  one.       Even  during 

the  splendid    weather    which 

we  now  are  enjoying,  people 

in  these  street-car-less  towns 

are    rapidly     coming    to    the 

bitter    realization     that    they 

made    a    mistake    in    permit- 
ting   their   car   lines    to    die. 

As    weeks    roll   by    and    the 

weather  becomes  worse    this 

lesson  will  be    more  forcibly 

impressed     upon     every    car 

rider. 

The  future  of    the    elec- 
tric railway    industry  will  D» 

made     brighter     every     time 

a    hapless    citizen     stands    '"n 

the  slush  on  a  windy  corner 

and  waits  in  vain  for  a  form  of  transportation  service 

which  will  adequately  take  the  place  of  his  street  car. 

Tlie  future  will  be  strengthened  every  time  a  merchant 

in  a  street-car-less  city  takes  aecounting  of  what  the 

abandonment  of  street  cars  has  meant    to    him    in    lost 

trade. 


P.  H.  Gadsen,  President 

Charleston  Consolidated  Railway  &  Lighting  Co, 

Vice-President,  United  Gas  Improvement  Co. 


428 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


The  Necessity  for  Publicity  in  Business 

G.  E.  TRIPP 

Chairman, 
Westinghouse  Electric  &  Mfg.  Company 

IT  MUST  be  a  matter  of  common  knowledge  that 
there  is  in  process  a  social  and  political  evolution 
in  this  country-  which  is  resulting  in  the  substitu- 
tion, to  a  constantly  increasing  extent,  of  government 
by  public  opinion  for  government  by  law. 

Government  by  law  is  a  characteristic  of  certain 
races,  of  which  the  Anglo-Saxon  is  the  outstanding  ex- 
ample, and  without  that  characteristic  our  forefathers 
could  not  have  established  our  form  of  government. 
Government  by  law  is,  therefore,  a  venerable  institution 
with  us  and  its  codes  and  precedents  are  the  product  of 
many  hundreds  of  years  of  experience  with  social 
actions  and  reactions.  It  has  become  a  science  so 
exact  and  important  that  no  educational  course  in  the 
curriculum  of  our  universities  is  more  prominent  or  at- 
tracts any  higher  order  of  intellect.  Our  judges  and 
lawyers  are  men  of  superior  ability  and  thoroughly 
trained  in  the  practice  of  law ;  in  other  words,  they  are 
experts  in  a  scientific  code  of  rules  upon  which  our 
social  and  business  relations  have  in  the  past  rested. 

The  departure  from  the  straight  and  narrow  path 
of  government  by  law  as  distinguished  from  govern- 
ment by  men  is  marked  by  the  establishment  of  certain 
types  of  government  bureaus  which  have  more  or  less 
jurisdiction  over  private  business  but  which,  on  the 
other  hand,  have  little  or  no  resemblance  to  courts  of 
law.  It  is  not  necessary  to  recount  the  large  and 
growing  number  of  State  and  Federal  Commissions 
and  Boards  in  order  to  prove  that  these  bureaus  have 
multiplied  rapidly  in  the  past  few  years  because  it  i;-. 
well  knowTi  to  everyone  and  the  development  of  these 
governmental  bodies  is  displayed  not  only  by  increasing 
numbers  but  also  by  the  widening  scope  in  the  essential 
ideas  of  their  mission  in  our  social  and  business  life. 
It  is  certainly  an  interesting  phenomenon  which  we  are 
witnessing  and  it  has  some  fundamental  aspects  which 
seem  to  demand  the  active  attention  of  men  of  broad 
business  experience. 

The  business  of  these  bureaus  is  generally  con- 
ducted by  men  who  are  not  trained,  either  by  education 
or  experience,  in  the  technique  of  the  particular  busi- 
ness or  industry  over  whose  destinies  they  preside,  nor 
have  there  been,  and  perhaps  because  of  the  very 
nature  of  their  functions,  can  these  regulator}'  bodies 
ever  build  up  a  system  of  procedure,  rules  and  prece- 
dents at  all  comparable  with  our  law  courts.  The  ap- 
pointment of  these  business  commissioners  is  wholly 
tree  from  restrictions  similar  to  those  surrounding  the 
appointment  of  our  judges  who  must  be  members  of 
the  Bar  and  by  custom  have  the  respect  and  approval 
of  their  associates.  Perhaps  the  most  important  dis- 
tinction, however,  is  the  uncertaih  tenure  of  office  of 
these  commissioners  and  the  fact  that  political  parties 


unfortunately  are  prone  to  regard  these  offices  as  a 
part  of  their  spoils. 

Certainly  bureaus  of  this  character  are  and  must 
be  sensitive  to  public  opinion  and  here  we  come  at 
once  to  the  duty  of  business  men  to  see  to  it  that  the 
public  has  full  and  accurate  information  upon  which  to 
form  an  opinion. 

Our  public  utilities  which  have  lived  under  regula- 
tion longer  than  the  rest  of  the  business  world,  have 
done  a  great  work  in  publicity  and  the  result  is  that 
public  sei"\'ice  commissions  have  come  to  be  more  and 
more  judicial  bodies.  Of  course,  even  in  their  case, 
there  is  still  a  necessity  for  keeping  the  public  con- 
stantly informed  as  to  business  facts,  and  there  always 
will  be,  if  a  sound  public  opinion  is  to  be  maintained, 
but  the  experience  of  the  public  utilities  is  a  lesson  to 
those  industries  which  are  just  beginning  to  feel  the 
interference  with  their  business  independence  by  new 
government  bureaus  or  extension  of  old  ones. 

It  is  a  question  whether  this  growing  governmental 
paternalism  could  have  been  avoided,  or  whether  the 
pendulum  will  swing  back,  but  surely  there  is  otie  safe 
course  and  that  is  continued  full  and  frank  publicity, 
to  the  end  that  public  opinion  may  be  based  upon  eco- 
nomic facts  instead  of  mere  sentiment  and  false  doc- 
trines. 


Public  Utility  Financing  for  the  Future 

ALLEN  B.  FORBES 

Harris,  Forbes  &  Company, 
New  York  Citj' 

PUBLIC  UTILITIES  are  public  necessities  to 
modern  civilization.  A  modern  community 
cannot  comfortably  and  safely  conduct  its  af- 
fairs without  a  comprehensive  central  system  to  pro- 
vide transportation,  telephones,  light,  heat  and  power. 
For  maximum  efficiency,  the  service  must  be  both  ade- 
quate and  reliable  and  must  expand  to  keep  pace  with 
the  growth  and  demands  of  the  community.  First- 
class  service  from  the  utilities  is  a  matter  of  concern 
and  direct  interest  to  every  citizen  whether  he  realizes 
that  fact  or  not,  as  it  directly  or  indirectly  affects  the 
conduct  of  every  business  and  every  household  in  the 
community.  The  deinagogue  inay  seek  to  confuse  the 
issue  to  further  selfish  ends  but  the  fact  remains  un 
changed  and  unch(ingeable. 

The  war  ha,s  been  a  great  educator  of  the  public. 
The  public  utilities  have  shared  in  the  new  light  that 
has  been  thrown  on  so  many  matters  as  a  result  of  that 
tremendous  struggle.  The  problems  of  the  railroads,  the 
street  railways,  the  lighting  companies  and  the  other 
public  utilities  have  received  a  great  deal  of  publicit)'. 
The  siinple  economic  proposition  that  these  companies 
cannot  continue  long  to  give  service  at  less  than  cost 
has  been  before  the  public  eye.  Politicians,  dema- 
gogues, socialists  and  "reformers"  to  the  contrary 
notwithstanding,  it  is  a  simple  fact  that  these  com- 
panies  cannot   continue   to   render   their   indispensable 


October,  1921 


THE   ELECTRIC  JOURNAL 


429 


public  services  unless  they  are  allowed  to  charge  rates 
that  produce  sufficient  income  to  pay  their  labor  bills, 
to  pay  their  material  bills  and  to  pay  reasonable 
"wages"  in  the  form  of  interest  and  dividends  on  the 
money  legitimately  invested  in  the  enterprise.  Good 
service  cannot  be  maintained  in  the  long  run  unless  all 
these  bills  are  paid  regularly.  The  additional  capital 
to  finance  extensions  necessary  for  the  public  service 
cannot  be  obtained  without  the  definite  prospect  of  re- 
ceiving its  "wages,"  any  more  than  additional  labor 
can. 

No  service-at-cost  plan  answers  that  does  not 
make  adequate  allowance  for  both  current  and  de- 
ferred maintenance  or  depreciation,  before  providing 
for  a  return  on  the  capital  invested.  Otherwise,  at 
least  part  of  the  specified  return  is  being  paid  out  of 
capital — that  is,  by  the  depletion  of  the  property.  The 
ideal  service-at-cost  plan  places  a  premium  on  first- 
class,  economical  management.  This  has  been  fairly 
worked  out  in  a  number  of  cases  where  any  decrease 
in  rates  charged  the  public,  below  a  certain  specified 
rate,  entitles  the  company  to  earn  and  pay  a  contem- 
poraneous and  corresponding  increase  in  the  annual 
rate  of  return  allowed  on  its  property  value. 

These  general  considerations  are  obvious  and  must 
eventually  be  the  basis  upon  which  public  utility  rates 
are  regulated.  In  fact,  the  rates  of  many  public  utili- 
ties are  already  being  regulated  on  this  basis.  Assum- 
ing that  this  basis  of  regulation  will  become  univer- 
sal, how,  in  the  public  interest  as  well  as  the  interest 
of  the  owners  of  the  property,  can  the  necessaiy  capital 
be  raised  to  the  best  advantage?  The  sale  of  mort- 
gage bonds  is  apt  to  be  the  first  thought,  but  that  only 
partially  answers  the  question,  if  in  fact  it  answers  it 
at  all.  It  does  not  answer  it  at  all  unless,  in  addition 
to  setting  up  a  sound  bond  issue,  a  sound  and  conser- 
vative and  workable  plan  for  junior  financing  is  also 
provided  for. 

Modern  public  utility  mortages,  generally  speak- 
ing, provide  that  bonds  may  be  issued  to  the  extent 
of  not  exceeding  75  or  80  percent  of  the  cash  cost  of 
permanent  additions  and  extensions  to  the  property. 
Conservative  principles  of  finance  dictate  that  not  too 
large  a  proportion  of  capital  requirements  should  be 
raised  on  borrowed  money.  Modern  thought  in  the 
best  informed  banking  circles  is  to  the  effect  that 
bonded  indebtedness  should  be  kept  down  to  an  ultra- 
conservative  figure.  In  the  interests  of  bond  investors, 
junior  security  holders  and  the  public,  about  three- 
quarters  of  the  cost  or  fair  value  of  the  property,  • 
whichever  is  the  smaller,  is  the  maximum  extent  to 
which  bonds  should  be  issuable  in  the  case  of  the  aver- 
age public  utility. 

Generally  speaking,  bonds  cannot  be  sold  at  par 
and  it  is  necessary,  therefore,  for  the  company  to  ab- 
sorb the  discount  at  which  the  bonds  are  sold.  As- 
suming, for  example,  that  bonds  are  issuable  to  the  ex- 
tent of  y^  percent  of  capital   expenditures,  and  those 


bonds  are  sold  by  the  company  at  90,  the  company  only 
receives  about  two-thirds  of  its  requirements  from  the 
sale  of  its  bonds,  leaving  the  balance  of  one-third  to 
be  procured  from  other  sources.  How  can  this  best 
be  accomplished?  The  next  best  security  to  its  mort- 
gage bonds  that  the  corporation  can  issue  is  an  unse- 
cured debenture  or  note,  but  if  we  subscribe  to  the 
sound  principle  above  referred  to,  that  too  large  a  pro- 
portion of  a  company's  capital  should  not  be  raised 
from  borrowed  money,  we  are  forced  to  discard  the 
unsecured  note  as  a  permanent  method  of  finance 
even  if  we  retain  the  possibility  of  creating  it  as  an 
emergency  measure. 

The  next  best  grade  of  security  that  is  available 
is  the  preferred  stock.  In  view  of  the  fixed  return 
thereon,  preferred  stock  must  have  an  investment  posi- 
tion to  be  marketed  successfully;  that  is  to  say,  its 
position  must  be  such  as  to  give  the  holder  reasonable 
assurance  that  he  will  continue  to  receive  the  fixed 
return  specified  on  the  face  of  the  stock,  and  that,  m 
the  event  of  liquidation,  his  principal  investment  in 
the  stock  will  be  good.  This  in  turn  presupposes  an 
equity  back  of  the  preferred  stock  and  a  suitable  mar- 
gin in  earnings  over  and  above  the  preferred  stock 
dividend  requirements.  The  principal  way  that  equi- 
ties are  built  up  over  preferred  stock  is  through  the 
medium  of  investment  represented  by  the  common 
stock  and  earnings  on  such  investment.  This  invest- 
ment may,  of  course,  represent  money  already  invested 
in  the  business  or,  in  the  case  of  new  common  stock  is- 
sues, additional  funds  going  in.  Again,  the  common 
stock  is  certainly  not  an  investment  and  not  even  an  at- 
tractive speculation  unless  there  is  a  reasonable  proba- 
bility that  the  investment  that  it  represents  will  be  al- 
lowed to  earn  sufficient  to  allow  for  a  liberal  return 
thereon.  In  other  words,  it  is  obvious  that  the  common 
stockholder  in  taking  all  the  speculation,  therefore,  is 
entitled  to  a  liberal  return. 

It  may  be  argued  that,  if  a  rate  of  return  is  al- 
lowed by  regulatory  authorities  on  the  entire  invest- 
ment in  the  property,  the  speculative  feature  is  elimin- 
ated from  even  the  common  stock,  but  an  argument 
ignores  the  fact  that  a  permissive  rate  of  return  is  by 
no  means  a  guaranteed  rate  of  return.  The  Cleveland 
Electric  Railway  plan  is  an  example  of  a  practically 
guaranteed  return,  but  there  are  very  few  such  in- 
instances  in  this  country. 

To  retiu'n  to  the  broad  proposition  of  future 
financing  of  the  public  utilities,  the  first  thing  to  be 
done  is  to  get  the  foundation  laid  for  a  strong  struc- 
ture of  sound  finance.  That  foundation  is  the  premi.'.e 
that  has  been  assumed  as  a  background  for  this  dis- 
cussion. To  establish  this  premise  as  a  universal 
fact  it  will  be  necessary  to  awaken  every  citizen  to  the 
proposition  that  the  public  utility  business  is  his  busi- 
ness; to  have  him  realize  the  direct  interest  that  he 
has  in  first-class  service  being  rendered  by  the  utility; 
and  to  demonstrate  that  directly  or  indirectly  he  has 


430 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


a  financial  interest  in  the  utilities  themselves.  If  he  is 
not  a  utility  security  holder  he  should  bear  in  mind 
that  there  are  fifteen  billion  dollars  of  public  utility 
securities  of  this  country  and  that  the  banks,  the  insur- 
ance companies  and  other  institutions  in  which  he  has 
a  direct  interest  are  among  the  owners  of  such  securi- 
ties. When  he  realizes  these  facts,  the  weight  of  uni- 
versal public  opinion  should  make  it  possible  for  every 
public  utility  to  get  fair  treatment  in  the  matter  of 
rates,  and  this  is  the  foundation  upon  which  any  per- 
manent plan  of  finance  must  be  laid.  Much  has  al- 
ready been  accomplished  along  these  lines  and,  com- 
bined with  the  educational  results  of  the  war  already 
referred  lo,  a  great  deal  of  light  has  been  thrown  on 
the  problems  and  purposes  of  such  enterprises. 

In  this  connection,  the  plan  of  selling  preferred 
stocks  to  the  customers  of  the  public  service  companies 
is  worthx-  of  mention.  Such  a  program— which  has 
been  cariied  out  successfully  in  a  large  number  of 
cases— ivures  to  the  benefit  of  all  concerned,  giving 
the  stockholder-customer  a  sound  and  well  paying  in- 
vestment, making  him  a  financial  partner  in  the  com- 
pany th:it  serves  him,  and  giving  him  an  insight  imo 
the  problems  of  the  company  and  an  understandmg 
and  sympathetic  point  of  view  in  connection  with  all 
its  affairs.  This  same  method  should  be  applied  m 
the  sale  of  common  stock,  so  that  the  public  served 
may  have  the  opportunity  to  become  full  partners  in 
the  business  without  a  fixed  limited  return  specified  ;is 
in  the  case  of  preferred  stocks. 

With  the  foundation  laid,  the  financial  strucUiie 
should  be  built  or  rebuilt  with  a  sound  conservative 
bond  issue  and  preferred  stock  and  common  stock. 
In  some  cases  perhaps  the  preferred  stock  would  be 
omitted,  but  the  three  classes  of  securities  are  desirable 
to  make  available  to  the  company  securities  to  meet 
varying  market  conditions.  The  new  series  mortgage 
gives  a  degree  of  fiexibility  on  the  issue  of  mortgage 
obligations  that  has  long  been  needed  and  which,  to  .i 
large  extent,  simplifies  bond  financing  for  the  future, 
as  the  prime  security  is  always  available  with  a  dur- 
ation and  a  face  rate  to  meet  current  market  condi- 
tions. The  bonds  will  be  buttressed  by  the  preferred 
and  common  stocks.  Possibly,  at  least  the  common 
stock  should  have  no  par  value,  so  that  arbitrary 
values  will  not  be  built  up  on  the  balance  sheet  and  the 
stock  can  be  sold  for  its  market  value  without  refer- 
ence to  an  arbitrary  par  value. 

The  primary  mistake  of  the  past  in  public  utility 
financing  has  been  the  lack  of  an  adequate  flexible  and 
workable  plan  of  junior  or  stock  financing.  Condi- 
tions for  which  the  companies  were  not  responsible, 
namely,  their  inability  to  charge  adequate  rates  to  per- 
mit the  earning  of  a  reasonable  return  on  the  capital 
invested  in  the  business,  have  militated  in  the  pa.st 
against  the  estabhshment  of  many  preferred  stocks 
and  most  common  stocks  in  a  position  that  made  them 
attracti\'e  and  salable  to  investors. 


The  universal  recognition  of  the  eqviity  and  jus- 
tice of  the  service-at-cost  plan,  which  takes  into  ac- 
count as  an  item  of  cost  the  wages  of  the  money  in- 
vested in  the  enterprise,  is  the  first  requisite  in  connec- 
tion with  public  utility  financing  for  the  future.  The 
second  requisite  is  a  conservative  and  well  balanced 
capitalization.  Such  a  capitalization,  with  the  bonded 
debt  limited  to  a  conservative  amount,  improves  the 
value  of  all  the  security  issues  of  the  company,  removes  ' 
the  menace  of  high  fixed  charges,  and  results  in  a  low- 
er average  cost  of  money  to  the  corporation  in  the 
long  run.  Most  important  of  all  from  the  point  of 
\  iew  of  the  public  interest,  such  a  capitalization,  based 
on  a  rate  situation  where  all  the  proper  and  reasona- 
ble elements  of  cost  and  value  have  received  fair  con- 
sideration, gives  the  maximum  of  facility  for  raising, 
on  the  best  terms  obtainable,  the  additional  capital 
that  must  be  provided  if  these  great  and  indispensable 
industries  are  to  continue  to  increase  their  facilities  to 
meet  the  steady  growth  and  demands  of  our  communi- 
ties and  thus  are  to  be  able  to  give  to  the  public  at  the 
lowest  cost,  the  first-class  service  to  which  it  is  entitled. 


The  Transportation  Business    A  World 
Fundamental 

M.  C.  BRUSH 

Vice-President, 
American  International  Corporation 

THE  M.\N  who  undertakes  to  prognosticate  in 
these  unsettled  days  of  readjustment  and  post- 
war conditions  the  outlook  for  the  electric  rail- 
way industry  or  any  other  industry  is  implying  that  he 
has  superknowledge  not  properly  given  to  anyone. 
One  has  but  to  look  back  over  the  period  since  1914  to 
be  thoroughly  convinced  that  no  man  or  group  of  men 
have  been  able  to  foretell  events  or  conditions  with  any 
reasonable  accuracy  for  even  a  few  months,  to  say 
nothing  of  a  few  years.  All  nations,  governments  and 
industries  are  completely  out  of  balance  and,  until  a 
new  and  steady  equilibrium  is  established,  no  one  can 
guess  the  future.  When  relations  between  nations,  be- 
tween governments  and  between  industries  have  settled 
down  to  a  steady  pace,  the  relative  impor- 
tance, power  and  necessities  of  nations  and  industries, 
as  well  as  separate  companies,  will  be  different  than 
previous  to  the  war.  In  this  gradual  settlement  to  an 
equilibrium  from  the  present  unbalanced  state  of 
affairs,  there  will  be  a  steady  grinding  effect,  resulting 
in  a  new  eventual  relationship  based  upon  the  survival 
of  the  fittest,  and  a  relative  strength  and  importance 
commensurate  with  new  international  and  national  eco- 
nomic conditions.  Just  where  the  electric  railway  in- 
dustry will  fit  or  what  the  relative  future  of  individual 
companies  will  lie.  is  impossible  to  foretell.  Matter^ 
both  national  and  international  are  still  in  a  chaotic 
condition.  The  world  as  a  whole  has  been  on  a  spree, 
and  all  affairs  are  not  yet  sufticiently  settled  and  read- 
justed to  radically  changed  conditions  to  warrant  any- 


October,   1921 


THE  ELECTRIC  JOURNAL 


431 


one  trying  reliably  to  guess  the  future.  This,  while 
true  of  industries  as  a  whole,  is  particularly  true  of 
those  industries  which  in  any  way  are  closely  allied 
with  or  dependent  upon  goxernmental  supervision. 
Therefore,  the  above  must  be  decidedly  applicable  to 
the  electric  railway  industry.  It  would  seem  possible, 
therefore,  at  this  time  for  us  to  only  try  to  weigh  con- 
ditions in  a  general  way  and  to  recognize  certain  fim- 
damentals  as  they  now  appear  to  exist,  while  at  the 
same  moment  we  should  apply  ourselves  with  an  in- 
tense earnestness  of  purpose  to  the  administration  of 
our  properties,  being  prepared  to  study  constantly  and 
observe  the  kaleidoscopic  and  daily  changes  in  condi- 
tions, with  a  willingness  to  modify  our  plans  and  poli- 
cies consistent  with  such  changes. 

In  contradistinction  to  the  past  two  or  three  years, 
every  man  today  must  promptly  recognize  that  he  is  an 
"order  getter"  instead  of  an  "order  taker".  This 
applies  decidedly  to  the  electric  raiKvay  industry-.  Rail- 
way executives  must  realize  now,  probably  more  than 
ever  before,  that  the}'  must  actually  sell  transportation 
and  they  must  do  those  things  which  tend  to  make 
their  product  attractive  to  their  customers.  There  is 
no  longer  any  justification  for  any  element  of  mystery 
which  has  sometimes  existed  in  regard  to  the  manage- 
ment of  transportation  companies.  The  public  as  well 
as  the  supervisory  bodies  are  now  too  vitally  a  party  to 
the  industry  and  to  the  management,  and  are  altogether 
too  well  informed,  for  a  manager  to  do  other  than 
recognize  that  facts  and  the  truth,  with  a  policy  of 
absolute  frankness  coupled  with  manifest  evidences  of 
r  desire  to  give  and  take  a  square  deal,  are  absolutelv 
the  best  policy.  There  is  cause  for  satisfaction  in  the 
fact  that  the  desperate  and  serious  period  through 
which  public  utilities  have  gone  has  resulted  in  a  great 
number  of  instances  in  a  full  recognition  on  the  part 
of  the  public,  the  press  and  governmental  authorities 
of  the  fact  that  the  "habit  of  mind",  fixing  the  so-called 
five  cent  unit  fare  has  been  dissipated  and  that  there 
is  an  inclination  on  the  part  of  those  affected  by  the 
unit  fare  to  agree  that  the  manufacturers  of  transiior^ 
tation  should  receive  such  payment  for  their  "goods" 
as  will  insure  their  healthy  existence.  This  makes 
still  more  important  the  right  attitude  on  the  part  of 
the  management  toward  the  public  and  public  authori- 
ties. It  would  appear,  therefore,  that  there  is  a  fertile 
field  for  electric  railway  executives  to  undertake  the 
arrangement  of  such  a  reciprocal  relationship  between 
the  man  who  sells  his  services  for  managerial  and  op- 
erating purposes,  from  the  chief  executive  down,  and 
the  man  who  buys  transportation,  as  will  insure  a  fair 
deal  and  a  fair  return  to  each.  The  question  of  a 
fair  return  to  the  man  who  sells  his  money  for  such 
purposes,  is  one  on  which  much  difi'erence  of  opinion 
exists  particularly  in  these  da\s  when  the  earning 
power  of  money  seems  so  dependent  upon  the  relia- 
bility of  the  continuity  of  return.  Fair  return  on 
capital  is  that  rate  which,  with  a  due  regard  for  the 
tafety   of   the   investment,   the   average   man   is   willing 


to  accept  for  the  use  of  his  money  whether  it  be  a 
hundred  dollars  or  one  hundred  thousand  dollars  and 
is  necessarily  a  matter  of  "money  competition".  The 
return  which  the  public  utilities  must  pay  is  that  which 
will  invite  new  capital,  and  this  rate  will  in  a  large 
measure  be  regulated  by  the  confidence  the  investor 
feels  that  the  industry  is  to  receive  fair  treatment  from 
the  public  and  governmental  authorities  as  well  as  effi- 
cient,    economical  and  intelligent  administration. 

The  decentralization  of  industry  which  is  growing 
since  the  intense  war  production  period  and  is  result- 
ing in  a  substantial  exodus  from  thickly  settled  dis- 
tricts to  rural  territory  should  tend  to  improve  the  field 
for  suburban  and  interurban  lines.  This,  coupled  with 
the  gradual  recognition  on  the  part  of  steam  railroad 
executives  that  comparatively  short  hauls  are  eco- 
nomically the  province  of  electric  lines,  should  make 
the  urban  and  interurban  manager  alert  to  grasp  the 
business  offered  even  to  the  extent  of  endeavoring  to 
create  new  movements  of  travel.  No  one  elment  will 
be  more  conducive  to  successful  salesmanship  of  such 
service  than  "Continuity  pf  Service".  The  average 
rider  is  not  so  critical  of  infrequent  service  as  he  is  to 
be  promised  definite  service,  and  then  find  such  irregu- 
larity in  actual  operation  as  to  make  it  impossible  for 
him  to  rely  upon  the  service.  Continuity  of  service 
can  be  secured  solely  through  excellent  management 
accompanied  by  the  keenest  co-operation  between  all 
cf  the  elements  which  go  to  make  up  the  operation  of 
an  electric  railway. 

Not  the  least  important  of  the  elements  thus  nec- 
essary, is  the  greatest  care  in  the  purchase  and  main- 
tenance of  equipment  for,  of  all  the  injurious  things 
tending  to  defeat  every  eft'ort  towards  cordial  public 
relationship,  there  is  nothing  which  will  cause  more 
criticism  than  poor  equipment  poorly  maintained, 
which  results  in  exasperating  delays  thereby  defeating 
the  passengers'  ability  to  anticipate  departure  or  ar- 
rival. Elaboration  on  this  element  of  transportation 
is  justified  in  view  of  its  being  one  of  the  several  ex- 
tremely important  elements  of  quality  of  service  so 
decidedly  necessaiy  in  successful  salesmanship  of 
transportation  to  customers.  In  the  last  analysis, 
therefore,  the  future  of  the  electric  railway  industry 
is  very  largely  dependent  upon  the  capacity  and  in- 
clinations of  electric  railway  executives. 

The  big  capable  executive  will  recognize  that  one 
of  the  great  fundamentals  of  the  world's  business  is 
transportation.  He  will  not  be  bound  by  past  prac- 
tices but  will  be  open  to  suggestions  and  criticisms,  and 
leadA-  and  desirous  of  studying  and  accepting  modified 
and  radical  changes  in  conditions,  and  ready  with  a 
thorough  knowledge  of  his  business  to  adapt  his  in- 
dustry and  his  ser\-ice  to  changing  conditions.  There 
is  no  reason  whv  he  cannot  render  a  necessary  service 
at  all  times.  He  must  further  adopt  the  policy  of 
frankness  with  the  sincere  determination  to  give  and 
insist  upon  recei\ing  a  square  deal,  and  by  so  doing  he 
will  go  a  long  way  towards  receiving  for  the  .oervice  his 


432 


THE   ELECTRIC  JOURNAL 


Vol.  XMII,  No.  lo 


industry  renders  a  fair  return.  The  whole  proposi- 
tion, therefore,  resolves  itself  into  good  salesmanship 
and,  in  order  to  sell  successfully  to  his  customers  and 
the  supervisory  authorities  this  sincerity  of  purpose,  he 
must  so  conduct  himself  as  to  compel  absolutely  confi- 
dence in  his  word,  his  judgment  and  his  sincerity. 


The  Problems  of  the  Street  Railways 

JOHN  H.  PA    DEE, 

President, 

J.  G.  White  Management  Corp.,  New  York  City 

Past  President,  American  Electric  Railway  Association 

THE  history  of  the  development  of  land  transpor- 
tation in  this  country  is  most  astounding.  It 
reveals  a  series  of  successes  with  few  failures 
and  demonstrates  the  great  value  to  industry  and 
society  of  a  system  which  rewards  individual  ingenuity 
and  effort.  At  all  periods  bold  men  have  had  visions 
of  the  necessities  of  the  future  and  have  built  on  broad 
and  economic  lines.  The  post  rider  gave  way  to  the 
stage  coach,  which  rapidly  developed  new  arteries  of 
travel ;  the  coach  was  displaced  by  the  Devvitt  Clintons, 
which  developed  into  the  enormous  and  powerful  steam 
locomotives,  hauling  the  20th  Centuries  of  the  present 
day. 

Speed,  safety,  comfort  and  economy  have  been  the 
watchwords  of  this  development  and  any  method  which 
did  not  combine  all  of  these  fell  by  the  wayside  and  was 
forgotten.  The  development  of  the  street  railway  as 
an  essential  system  of  transportation  resulted  from  the 
gathering  of  large  numbers  of  people  into  confined 
areas,  the  increasing  dimensions  of  such  areas  and  the 
necessity  for  speed,  safety,  comfort  and  economy  in 
moving  them  from  one  section  to  another  for  indus- 
trial, commercial  and  social  purposes.  Many  of  us 
have  seen  the  problem  of  this  industry  grow  from  one 
of  transporting  comparatively  few  each  day  to  one  of 
transporting  over  thirty  millions  every  twenty-four 
hours,  or  eleven  billions  per  annum,  or  one  hundred 
times  the  total  population  of  this  country  each  year. 
The  money  of  our  citizens  invested  in  these  enterprises 
has  increased  to  over  six  billions  of  dollars,  an  amount 
equal  to  one-c]uarter  of  the  total  funded  debt  of  the 
United  States  at  the  present  time. 

Electricity,  and  electricity  alone,  has  made  this 
great  development  possible.  The  horse  drawn  bus  and 
the  mule  drawn  car  on  rails  gave  way  to  the  speedy, 
and  comfortable  electric  railwaj'  car;  the  cities  were 
gridironed  with  tracks ;  cities,  tcnvns,  villages  and  ham- 
lets were  connected ;  improvements  of  all  kinds  kept 
pace  until  today  we  have  in  the  United  States  a  magni- 
ficent system  of  urban  and  interurban  transportation. 
But  our  cities  and  towns  are  steadily  and  surely  grow- 
ing and  transportation  facilities  must  be  extended  and 
increased. 

What  of  the  future?  History  shows  that  the 
street  railway,  and  by  that  is  meant  all  forms  of  local 
trolley  transportation,  is  absolutely  essential  to  our 
economic   life.     Its   facilities   are   used  largely   by   the 


wage  earners  and,  hence,  must  be  furnished  at  a  price 
within  the  user's  means.  Electricity  will  propel  cars 
per  unit  of  transportation  more  economically  than  any 
other  form  of  motive  power,  consistent  with  the  speed 
and  comfort  obtained.  However,  the  electric  railway 
must  have  tracks  for  its  cars.  The  investment  in 
tracks  is  large  and  this  cost  distributed  to  the  passenger 
is  material  in  amount,  especially  in  sparsely  settled 
communities.  However,  with  electric  railways  follow- 
ing main  arteries  of  travel,  or  in  thickly  populated 
areas  the  .amount  of  the  track  investment  charge  dis- 
tributed to  each  passenger  is  small.  For  heavy  and 
frequent  traffic  no  other  form  of  transportation  has  ap- 
proached the  electric  railway. 

But  what  of  the  claims  made  by  the  advocates  of 
transportation  by  gasoline  vehicles?  Busses  were  op- 
erated years  ago  by  animal  power  and  were  discarded. 
They  are  again  made  possible  by  the  gasoline  motive 
power  and  by  the  hard  surface  highways.  The  last  is, 
however,  the  compelling  reason.  Let  us  assume  that 
they  are  capable  of  handling  the  transportation  of  a 
reasonably  large  city,  although  recent  experirrients 
have  demonstrated  its  impossibility.  They  are  no  more 
comfortable  than  a  street  car,  they  have  no  greater 
speed,  they  are  not  as  safe,  and  above  all  they  are  less 
economical  in  operation,  than  a  street  car  of  the  same 
carrying  capacity.  The  cost  of  labor,  machinery  and 
supplies  are  not  material  in  the  comparison  as  such 
costs  affect  both.  In  spite  of  the  prevalence  of  the 
jitney,  in  spite  of  the  claims  of  motor  bus  manufac- 
turers, and  in  spite  of  the  clamor  of  those  who  for 
political  or  other  reasons  are  plotting  the  ruin  of  exist- 
ing local  transportation  systems,  electric  transportation 
upon  rails  remains  the  cheapest,  the  most  reliable  and 
the  most  convenient  method  of  mass  transportation 
that  now  exists,  and  there  is  no  indication  that  it  is  to 
be  supplanted  in  the  future. 

When  all  costs  of  service  are  assessed,  the  electric 
railway  shows  a  substantial  margin  of  economy  over 
the  motor  bus,  and  it  is  only  because  the  public  is  as- 
suming as  public  charges  a  substantial  portion  of  the 
costs  of  motor  bus  operation,  while  at  the  same  time 
levying  against  the  electric  railway  charges  that  are 
totally  unconnected  with  its  operation,  that  even  a  pre- 
tense of  lower  bus  cost  is  possible.  The  bus,  whatever 
its  motive  power,  on  account  of  its  lack  of  need  of 
tracks,  is  and  has  a  function  to  perform  in  the  great 
scheme  of  transportation.  Its  field  is  in  areas  of  light 
irafiic  and  extensions  of  routes  which  will  not  warrant 
the  heavy  investment  in  tracks.  However,  the  gasoline 
bus  is  not  the  bus  that  will  play  a  necessary  and  satis- 
factory part  in  the  facilities  of  the  future.  It  will  be 
some  form  of  electrically-propelled  bus  and  will  not 
have  the  odorous  discomforts  to  passengers  and  the 
excessively  high  maintenance  costs. 

The  only  other  competitor  of  the  electric  street 
car  is  the  individually-owned  automobile  and  that  is 
not  a  competitor  in  the  strict  sense  of  the  word.  The 
owner  of  the  automobile  ceases  to  require  the  car  ser- 


October,  192 1 


THE   ELECTRIC  JOURNAL 


433 


vice.  In  the  smaller  communities  the  loss  of  patron- 
age so  occasioned  is  of  considerable  amount  and  vital 
to  the  success  of  the  electric  railway  system.  The  rail- 
way business  is  exactly  the  same  as  an  industrial  enter- 
prise, the  product,  which  in  this  case  is  transportation, 
must  exceed  some  certain  percent  of  its  productive  ca- 
pacity or  there  will  be  no  return  to  the  investor.  Al- 
ready street  railways  have  been  abandoned  in  some  of 
the  smaller  communities  because  they  have  become 
economically  impossible. 

From  a  strictly  business  standpoint,  the  electric 
railways  are  emerging  from  a  period  of  business,  social 
and  industrial  upheaval,  better  acquainted  with  their 
own  powers  and  possibilities  and  with  better  knowl- 
edge of  their  own  costs.  They  have  passed  from  the 
stage  of  experimentation  to  one  of  sound  business  pro- 
duction and  are  now  on  a  firm  foundation  for  future 
operation  and  expansion. 

Turning  to  the  consideration  of  another  phase  of 
the  development : — No  private  enterprise  furnishing 
service  to  the  individual  or  public  can  succeed  or  con- 
tinue, except  by  Government  subsidy,  unless  the  in- 
come exceeds  the  expenses.  In  the  earlier  days,  com- 
munities and  officials  thereof  welcomed  with  open  arms 
the  electric  railway  builder  and  offered  him  many  in- 
ducements. Railways  were  built  and  became  at  once 
successful  financially,  whereupon  there  was  a  rush  of 
building  which  became  so  keen  that  there  was  created 
an  opportunity  for  governing  officials  to  impose  or 
withhold  restrictions  and  conditions  in  permits  or 
franchises  either  for  their  own  personal  benefit  or  for 
the  supposed  protection  of  the  people.  Unwisely  many 
railway  builders  accepted  conditions  which  were  un- 
justified in  law  and  equity  and  which  later  became  too 
burdensome.  During  these  years,  partly  due  to  the 
methods  pursued  by  the  railway  operators  themselves, 
but  mostly  due  to  the  attempts  on  the  part  of  unscrupu- 
lous office  holders  and  candidates  for  office  to  make 
political  capital,  there  grew  up  an  attitude  of  hostility 
to  public  service  companies  on  the  part  of  the  public. 
Demagogues  told  the  public  that  it  was  being  unjustly 
treated  and  the  public  believed  them.  Legislation  was 
resorted  to  and,  in  an  attempt  to  punish  the  railways, 
public  service  commissions  were  created  to  protect  the 
public.  These  commissions  soon  found  that  in  most 
cases  the  railways  themselves  needed  the  protection 
from  a  public,  which  was  unwittingly,  and  from 
governing  officials,  who  were  viciously,  asking  more 
than  was  fair  and  just.  The  work  of  the  various  regu- 
lating commissions  on  tlie  whole  has  been  salutary, 
constructive  and  particular!}-  productive  of  a  better  un- 
derstanding of  the  questions  involved. 

The  great  war  came  with  its  disruptions  and  sud- 
denl>-  the  railways  and  the  public  came  face  to  face 
with  the  fact  that  this  great  and  essential  industry 
might  collapse  and  be  lost.  State  commissions,  the 
Presidential  commission,  and  courts,  legislatures, 
financiers,  railway  owners  and  investors,  the  press  and 
the    public    joined    with    one    accord    in    thoughtfully 


studying  the  questions  involved.  It  was  not  to  be 
wondered  at  for  this  industry  is  so  vital  to  the  economic 
and  social  life  of  our  communities,  and  six  billion  dol- 
lars of  invested  savings  were  at  stake. 

What  has  been  the  result  of  all  this  agitation  and 
investigation  ? 

In  the  first  place  it  has  been  demonstrated  that  the 
electric  railway  as  a  means  of  local  transportation  is  an 
absolute  necessity  and  must  be  protected  and  fostered. 

In  the  second  place,  the  public  has  been  educated 
quite  largely  as  to  the  facts  and  principles  involved 
and  consequently  it  is  willing  to  accord  fair  treatment 
which  has  taken  the  form  of  consents  in  many  com- 
munities for  higher  rates  of  fare. 

In  the  third  place,  the  regulating  bodies  have 
found  that  the  public  and  the  courts  require  them  to 
protect  property  rights  and  preserve  the  industry  for 
the  people  by  fair  and  constructive  treatment  of  all 
such  questions. 

In  the  fourth  jilace,  the  courts  have  been  called 
upon  to  determine  many  questions  not  heretofore 
passed  upon  and  such  decisions  have  shown  that 
property  and  invested  capital  of  public  service  railways 
cannot  be  ruthlessly  destroyed  or  dissipated  by  the 
malicious  acts  of  politicians. 

In  the  fifth  place,  the  public,  the  regulating  bodies 
and  the  courts  are  realizing  and  enunciating  the  prin- 
ciple that  the  rate  of  fare  depends  upon  many  condi- 
tions and  that  the  impositions  of  unfair  burdens  which 
tend  to  increase  that  rate  are  discriminatory  as  affect- 
ing the  car  rider.  The  car  riders  have  found  that  they 
are  paying  the  bills  and  are  insisting  that  they  be  not 
called  upon  to  bear  burdens  which  are  not  related  in 
any  way  to  the  service  they  receive. 

In  the  sixth  place,  the  owners  and  operators  of 
electric  railways  know  their  strength  and  their  weak- 
ness, and  appreciate  as  never  before  the  solidity  of  the 
industry's  foundation  and  structure. 

In  the  seventh  place,  all,  or  nearly  all,  now  realize 
that  it  is  for  the  benefit  of  all  that  the  street  railway 
industry  shall  still  continue  to  be  fostered,  developed, 
owned  and  operated  by  private  capital.  Municipal 
ownership  is  not  popular  with  the  sensible  American 
public. 

The  one  great  question  which  confronts  the  indus- 
try today  is  that  of  financing  maturing  obligations  an'd 
providing  funds  for  future  extensions  of  tracks  and 
equipment  to  meet  the  needs  of  the  public.  Such  funds 
must  be  obtained  from  a  cautious  investor  who  has 
absolute  control  over  his  investment  acts.  A  true  pic- 
ture can  be  painted  which  must  be  so  attractive  that 
he  cannot  withhold  his  aid.  Here  is  an  industry  Which 
has  a  product  which  must  always  be  used  and  in  ever- 
increasing  quantities,  an  industry  which  has  been 
through  the  fiery  furnace  of  the  war  conditions  and 
emerges  purified,  justified  and  protected  as  no  ordinary 
business  industry  in  our  history.  Mistakes  in  any  in- 
dustry have  been  and  always  will  be  made,  but  the 
basic  principles  are  the  true  test,  the  busiijess  of  the 


434 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  10 


street  railway  always  goes  on  in  prosperity  or  adversity 
and  while  the  price  of  its  securities  may  go  down  in 
times  of  world  upheavals,  yet  its  path  is  not  strewn 
with  the  junk  heaps  of  many  other  forms  of  industrial 
enterprises.  The  electric  railway  as  the  main  and  de- 
pendable system  of  urban  transportation  is  and  will  re- 
main supreme,  the  bus  will  occupy  a  secondary  or 
auxiliary  position  as  a  part  of  the  main  system  and  the 
present  piratical  operation  will  disappear.  Further- 
more, the  gasoline  bus  except  for  sporadic  operations 
will  be  laid  aside  and  the  electric  motor  bus  as  an  in- 
tegral adjunct  to  the  electric  railway  will  find  its  proper 
sphere. 

The  Problem  of  Mass  Transportation 

EDWARD    DANA 

General  Manager, 
Boston   Elevated   Railway   Company 

A  THIRD  of  a  centur}^  ago  the  phrase  '"Mass 
Transportation"  would  certainly  have  had  an 
unfamiliar  sound.  Today  one  visualizes  at  once 
the  size  of  the  problem  which  is  involved.  The  tech- 
nical advance  during  this  period  of  time  in  the  histoiy 
of  urban  transportation  has  been  most  varied  and  has 
engaged  the  attention  of  many  minds. 

The  street  railway  was  to  a  great  extent  the  agency 
which  created  the  problem  of  mass  transportation,  and 
today  we  ask  how  that  agency  can  best  be  adapted  to 
this  purpose.  The  histor}'  of  electric  traction  is  almost 
as  varied  as  are  the  communities  which  it  serves. 
Local  conditions,  geographical  as  well  as  psychological, 
have  determined  the  trend  of  development  of  each  of 
the  many  local  systems.  We  have  today  urban,  sub- 
urban, interurban,  as  well  as  overhead  and  under- 
ground rapid  transit  systems;  each  in  its  own  way 
striving  to  function  so  as  best  to  meet  the  needs  of  its 
locality. 

It  is  a  question  whether  it  is  possible,  or  worth 
while,  to  attempt  to  arrive  at  the  best  solution  of  mass 
transportation,  and  thus  set  up  a  theoretically  perfect 
unit  which  in  all  human  probability  never  could  be  at- 
tained. Certainl)'  such  an  ideal  would  not  fit  nicely  the 
local  requirements  of  communities  so  entirely  different 
in  character  and  vastly  different  as  to  size  and  rapidity 
of  growth.  Out  of  the  hard  earned  experience  of  the 
past,  however,  has  come  knowledge  which  should 
be  utilized  wherever  possible  in  order  to  permit  existing 
systems  to  function  efficiently  and  satisfactorily  and  to 
permit  new  systems  or  extensions  to  be  based  upon  a 
somewhat  more  satisfactory  foundation  than  much  of 
the  expansion  of  the  past. 

It  is  probabl)'  true  that  operating  costs  of  urban 
properties  will,  for  some  time  to  come  at  least,  remain 
relatively  high  and  that  satisfactory  service  and  effi- 
cient operation  will  require  an  effort  to  increase  the 
load  factor  of  travel  and,  without  sacrificing  flexibility 
of  service,  will  necessitate  handling  passenger  traffic 
more  in  bulk  than  was  done  in  the  early  period. 


In  most  cities  there  is  a  well  defined  area,  usually 
known  as  the  "Delivery  District."  Modern  building 
construction  has  greatly  increased  the  number  of  in- 
dividuals and  consequently  the  volume  of  business  that 
can  be  transacted  within  this  area.  In  most  large  cities 
it  would  be  a  physical  impossibility  during  the  maxi- 
mum hour  to  transport  the  volume  of  traffic  which 
offers  itself  entirely  on  the  surface  and  by  a  multi-^ 
plicity  of  routes.  Surface  congestion  would  result. 
Irregular  spacing  and  loading  of  individual  cars  at- 
tempting to  transport  people  reasonably  near  their  des- 
tination would  cause  slow  movement  and  long  waits 
for  individual  routes. 

Elevated  stinictures  and  subways  permit  concen- 
tration of  traffic  and  by  increasing  the  load  factor  thus 
permit  economical  handling  of  large  volumes  of  people. 
The  initial  cost  of  these  are  great  and  they  can  never 
be  justified  for  the  operation  of  single  cars.  The  in- 
creased capacity  for  single  car  operation  is  no  greater 
than  a  reserved  space  on  a  highway.  Efficient  and 
satisfactory  service  can  come  only  by  the  operation  of 
trains  of  several  units  at  frequent  intervals. 

When  rapid  transit  thoroughfares,  so-called,  be- 
come a  necessity,  there  comes  a  moment  when  the 
greatest  consideration  must  be  given  to  a  comprehen- 
sive planning  for  the  growth  of  the  future  mass  trans- 
portation of  the  city.  There  are  today  examples  of 
expensive  construction  of  this  character — ill-advised 
and  serving  no  useful  purpose  in  the  future  plans. 
Stations  have  been  constructed  to  satisfy  the  political 
ends  of  those  advocating  them  without  regard  for  their 
need  or  effect  upon  the  mass  transportation  of  the  sys- 
tem of  which  they  form  a  part.  When  the  important 
step  of  rapid  transit  thoroughfares  has  been  taken,  de- 
velopment should  henceforth  be  made  along  the  lines 
embarked  upon  and  the  future  molded  step  by  step. 

In  the  early  days,  people  were  in  the  habit  of  rid- 
ing from  their  front  doors  to  their  place  of  business. 
While  transferring  is  b)'^  no  means  an  ideal  pastime,  it 
becomes  a  necessary  evil  in  the  economical  handling  of 
mass  transportation.  Rapid  transit  thoroughfares 
ought  to  be  constructed  to  transport  large  volumes  of 
traffic  between  termini  from  which  it  can  be  distributed 
further  over  a  wider  area  by  different  t\pes  of  serv- 
ice best  adapted  to  the  particular  volume  of  traffic. 

In  Boston  an  average  of  972000  passengers  are 
carried  throughout  the  year  on  week-days,  on  459  miles 
of  active  track  on  the  surface,  in  the  subways  and  on 
the  elevated.  Approximately  twelve  percent  of  the 
active  mileage  is  in  elevated  or  subway  rapid  transit 
lines,  and  over  this  twelve  percent  of  mileage  eighty 
percent  of  the  daily  travel  is  distributed. 

Unless  the  load  factor  of  rapid  transit  lines  is 
given  attention  in  this  respect,  a  co-ordinated  eco- 
nomical transportation  system  cannot  be  constructed, 
as  there  would  exist  much  duplication  and  consequent 
waste  expense.  In  other  words,  as  soon  as  such  an 
artery  has  been  placed  in  operation,  other  lines  should 
not    be    operated    in    competition    with    it,    but    efforts 


October,  1921 


THE   ELECTRIC  JOURNAL 


435 


should  be  made  to  concentrate  tratitic  by  increasing  its 
use. 

It  has  already  been  proxen  that  the  extension  of 
surface  lines  into  growing  territory  before  there  is 
sufficient  justification  has  seriously  hampered  man}-  a 
property.  Similarl}-,  the  construction  of  rapid  transit 
arteries  paralleling  territory  previously  served  by  sur- 
face lines,  with  a  capacity  greatly  in  excess  of  the  im- 
mediate use  and  waiting  for  traffic  to  develop  (which 
in  time  of  course  it  will)  means  in  the  meantime  an 
even  greater  burden. 

Given  a  comprehensive  plan  for  the  rapid  transit 
arteries  of  an  urban  community  of  large  size,  the  de- 
velopment of  the  secondary  so-called  feeder  lines  oflrers 
opportunity  for  a  wide  variety  of  treatment.  These 
lines  and  their  arrangement  call  for  constant  stud}'  and 
readjustment  in  order  to  provide  speed  and  frequenc}-. 
Large  type  motor  cars,  motor  and  trailer  units,  three- 
car  trains,  safety  cars,  motor  bus  or  trackless  trolley 
units  offer  a  variety,  the  choice  of  which  must  be 
governed  by  the  locality  served. 

It  is  quite  obvious  that  tributary  territory,  where 
there  is  no  element  of  congestion,  cannot  grow  as 
readily  by  the  application  of  the  principle  of  mass 
transportation  as  by  an  effort  to  provide  frequent, 
rapid  and  comfortable  service  to  and  from  terminals  of 
rapid  transit  thoroughfares :  and  the  load  factor  of 
rapid  transit  arteries  can  be  increased  only  by  the  de- 
velopment of  tributary  territory. 

It  is  fair  to  conclude  that  rapid  transit  thorough- 
fares, either  subway  or  elevated,  are  only  warranted 
where  traffic  can  be  concentrated  in  sufficient  volume 
to  call  for  operation  of  trains  at  fairl}»  frequent  inter- 
vals. Such  concentration  can  be  obtained  by  the  dis- 
continuance of  parallel  surface  lines,  thereby  removing 
street  congestion,  and  the  development  of  tributary 
territory,  the  load  being  brought  in  and  transferred  at 
terminals.  This  tributary  territor}-  in  every  Case  pre- 
sents a  problem  in  which  local  conditions  will  deter- 
mine the  degree  of  mass  transportation  which  can  best 
be  employed. 


The  Outlook  for  the  Next  Five  Years 

PHILIP  J.  KE.'\LY 

President, 
Kansas  City  Street  Railways  Company 

IN  THE  DARK  DAYS  of  1918  and  1919  the  writer 
had  occasion  to  read  a  number  of  papers  and 
take  part  in  many  discussions  concerning  the  then 
extremely  perilous  situation  affecting  urban  transpor- 
tation companies.  In  all  of  these  discussions,  there 
was  an  effort  to  be  optimistic,  although  at  times  it 
seemed  as  if  optimism  was  out  of  place  and  the  future 
held  little  encouragement.  This  viewpoint  was  based 
on  the  fundamental  facts  that  nothing  had  at  any  time 
been  devised  to  take  the  place  of  the  electric  street 
railway  in  our  large  cities;  that  transportation  was  ab- 
solutely essential  to  the  growth  and  well  being  of  exerv 


city,  and  that  what  was  essential  and  necessary  must 
and  would  be  preserved  and  supported.  Our  civiliza- 
tion cannot  exist  without  the  essentials. 

The  reversal  of  the  causes  which  brought  about 
almost  complete  disruption  of  the  transportation  indus- 
try in  the  United  States  will  work  for  its  revival. 
Only  the  essential  nature  of  the  street  railway  business 
has  kept  it  alive  in  the  past  four  years.  It  simply  had 
to  go  on,  and  it  did,  at  the  expense  of  those  who  had 
invested  some  four  billions  of  dollars,  that  the  citizens 
of  the  United  States  might  have  transportation  facili- 
ties. Wages  and  materials  doubled  in  price  until  at 
the  peak  it  cost  from  $2.25  to  $2.50  to  buy  what  one 
dollar  used  to  do  in  pre-war  days.  The  average  in- 
crease in  expenses  was  easily  125  percent;  whereas,  the 
.ixerage  increase  in  fare  was  certainly  not  over  50  per- 
cent, although  in  some  few  cases  100  percent  increase 
was  given.  Furthermore,  fare  increases  were  not  con- 
temporaneous with  the  increase  in  expense,  due  to  the 
immobility  of  governing  bodies  and  the  reluctance  of 
commissions  to  increase  fares.  In  some  cases  bank- 
ruptcy was  reached  before  relief  was  given.  Other 
companies  were  able  to  weather  the  storm  without  be- 
ing forced  to  the  courts.  They  were  those  favorably 
situated,  with  large  reserves,  or  in  states  where  the 
commissions  acted  promptly  to  relieve  the  situation. 
Many  of  the  largest  companies  however,  in  the  end 
were  forced  into  receiverships,  in  order  to  make 
possible  a  continuation  of  service  and  to  protect  their 
owners.  (3ne  at  least  has  suspended  operation.  In 
addition  to  increased  expenses,  there  was  a  recurrence 
of  jitney  competition,  which  in  many  cities  has  been 
equall}-  responsible,  with  hi^h  ]irices,  for  bankruptcy. 
This  was  due  in  large  part  to  higher  street  car  fares, 
which  made  it  possible  for  jitneys  again  to  compete 
with  some  measure  of  success. 

The  essential  nature  of  the  industry  has  been  em- 
phatically demonstrated  in  Bridgeport,  Connecticut; 
Toledo,  Ohio ;  and  Des  Moines,  Iowa.  In  all  of  these 
cities  street  railway  service  was  suspended.  Each  is 
convinced  that  jitney  and  motor  bus  transportation 
cannot  supplant  the  service  given  by  the  street  railway. 
In  Bridgeport,  after  six  weeks  of  suspension,  with 
every  opportunity  given  to  the  entire  jitney  association 
of  the  State  of  Connecticut  to  show  what  could  be 
done,  the  people  decided  that  they  wanted  the  electric 
cars  returned.  The  most  recent  example  is  Des 
Moines,  where  at  this  writing  there  has  been  no  car 
service  for  three  weeks.  Motor  busses  and  jitneys 
have  been  unable  to  meet  the  demands  of  the  public, 
merchants  have  suffered  a  loss  of  business  and  at  the 
present  an  effort  is  being  made  to  have  the  courts  order 
a  resumption  of  car  service. 

The  industry  toda\-,  although  there  are  several  lean 
years  ahead  of  it,  after  credit  has  been  restored  again 
will  come  into  its  own.  The  five  cent  fare  is  no  more. 
The  biggest  handicap  with  which  the  business  had  to 
contend  has  been  remo\ed,  and  never  again  will  I't  have 


436 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


to  suffer  the  results  of  an  inflexible,  fixed  price  for  its 
product  regardless  of  production  costs.  Various  rates 
of  fare  the  country  over  have  been  established  and, 
although  there  will  be  reductions,  they  will  be  made 
more  slowly  than  were  the  increases  and  there  will  be  a 
closer  relation  between  the  cost  of  service  and  fare 
reductions.  The  initiative .  and  the  burden  of  proof 
will  not  be  upon  the  railways.  The  position  of  tlie  in- 
dustry in  this  respect  has  been  much  strengthened  by 
commission  and  court  decisions  relative  to  the  rate  of 
return ;  and,  before  fares  are  reduced,  it  will  be  neces- 
sary to  show  that  excessive  earnings  are  being  made 
under  the  present  rates. 

Furthermore,  the  public  has  been  better  educated 
to  the  needs  of  utilities.  The  widespread  publicity 
given  to  street  railway  matters  in  every  city,  due  to 
local  problems,  and  the  necessity  for  fare  increases,  has 
awakened  the  public  to  the  necessity  of  dealing  more 
liberally  with  transportation  companies.  The  steam 
railway  situation,  the  President's  Committee,  the  inves- 
tigation of  local  chambers  of  commerce  have  all  tended 
to  waken  the  public  conscience. 

Material  prices  and  labor  are  descending  slowly  to 
a  more  normal  level.  In  the  past  year  there  have  been 
decided  reductions.  This  is  especially  true  of  coal  and 
steel  products.  There  has  been  approximately  lo  per- 
cent reduction  in  street  railway  labor  costs  in  th*e  past 
year,  and  there  will  be  further  reductions,  although  it  is 
doubtful  if  labor  will  ever  again  reach  the  pre-war  level. 
Unrestricted  jitney  competition  is  lessening  and  the 
necessity  for  regulation  has  become  apparent  to  every 
municipality.  The  examples  of  Bridgeport  and  Des 
Moines  have  fairly  well  proven  that  two  systems  of 
transportation  cannot  successfully  exist  together  and  in 
competition.  There  has  been  a  let-up  in  the  auto- 
mobile industry  and  to  some  extent  a  less  widespread 
use  of  the  private  automobile. 

Management  has  improved  during  the  war  period. 
Necessity  has  been  the  mother  of  invention  and  lessons 
of  strict  economy  which  were  learned  will,  without 
doubt,  have  a  salutary  effect  on  future  operations.  A 
better  class  of  employes  has  entered  the  business,  at- 
tracted by  high  wages  paid  in  the  past  three  years. 
This  has  been  reflected  in  better  transportation,  more 
courteous  and  careful  employes. 

The  great  problem  now  confronting  the  industry 
is  the  difficult  and  almost  insurmountable  one  of  estab- 
lishing credit  for  new  capital  imperatively  essential  for 
extensions,  improvements  and  the  retirement  of  matur- 
ing securities.  A  year  ago,  it  was  estimated  that  at 
least  three  hundred  million  dollars  was  then  needed 
for  immediate  improvement,  and  this  figure  is  certainly 
not  less  today.  In  addition,  millions  of  dollars  of  long 
term  bonds  and  short  time  notes  are  maturing  and  de- 
mand immediate  refinancing.  Although  operating 
problems  are  becoming  easier  and  earnings  will  doubt- 
less gradually  become  better,  this  phase  of  the  situation 
is  one  that  will  demand  the  best  thought  of  the  in- 
dustrv. 


The  financial  situation  has  not  turned  for  the 
better  and  probably  will  not  for  several  years.  Most 
of  the  long  term  bonds  now  or  presently  maturing 
were  sold  under  extremely  favorable  conditions. 
There  was  then  an  active  market  for  utility  invest- 
ments and  long  term  issues  were  easily  underwritten 
on  a  five,  five  and  a  half  and  six  percent  basis.  The 
industry  was  extending,  wages  and  materials  were  low 
and,  because  of  cheap  money,  good  net  earnings  were 
shown  and  dividends  paid.  Traction  properties,  how- 
ever, were  limping  even  prior  to  the  war,  and  many  of 
tliem  were  able  to  continue  dividend  payments  only  be- 
cause of  the  low  rates  on  their  long  term  debt. 

At  present,  unfortunately,  issues  are  maturing  and 
capital  improvements  are  imperative  under  extremely 
unfavorable  conditions.  The  investing  public  has  been 
frightened  away  from  the  utility  market,  at  least  from 
street  railway  securities.  Net  earnings  either  do  not 
exist  or  are  inadequate.  There  is  an  extremely  tight 
money  market  with  no  prospects  of  easing  up  for  some 
time.  This  means  that  immediate  financing  must  be 
through  short  term  issues,  for  which  exorbitant  fates 
are  charged.  It  will,  therefore,  take  some  years  of 
good  earnings,  favorable  public  attitude  and  falling 
material  markets  before  street  railway  issues  will  again 
become  attractive  to  the  investing  public. 

To  secure  the  proper  public  attitude,  service  must 
be  better  than  ever  before.  For  high  fare  and  better 
treatment  the  public  expects  and  demands  the  best 
quality  of  utility  service.  The  increasing  competition 
of  the  busses  and  its  threatening  extension  is  an  im- 
pelling reason  in  addition  why  there  must  be  no  let-up 
in  the  service  given.  Service  is  a  comprehensive  word 
and  means  many  things.  It  means  adequate  cars,  well 
lighted,  well  cleaned  and  well  maintained.  It  means 
proper  loading  standards.  It  means  well  trained, 
courteous  and  efficient  employes.  But,  in  addition,  it 
means  that  the  local  traction  company  must  be  pre- 
pared to  extend  its  service  to  meet  growing  demands 
of  the  city,  and  to  provide  traction  facilities  in  advance 
of  these  demands.  It  means  keeping  the  property  in 
condition  to  render  a  proper  public  service.  All  these 
things  require  money  for  capital  improvements. 

Upon  the  management  is  placed  a  three-fold  ob- 
ligation: that  of  adequate  service  to  the  public,  attrac- 
tive wages  to  employes,  and  a  good  return  to  the  in- 
vestor. As  the  matter  stands  today  only  one  of  these 
requirements  is  being  met,  that  is,  the  wages  now  being 
paid.  The  investor  is  suffering  and  there  has  not  been 
for  the  past  three  years  a  possibility  of  providing  the 
capital  improvements  necessary  to  render  the  character 
of  service  that  must  be  maintained. 

The  outlook  then  for  the  next  five  years  is  one  of 
hard,  unremitting  drudgery  for  the  operator,  before 
the  industry  is  again  attractive  to  the  investing  public. 
This  very  fact,  however,  brings  us  back  to  the  original 
proposition — street  railways  are  essential  and,  being 
essential,  they  will  be  supported.  Many  things  are  now 
working  together  for  the  benefit  of  the  industry  and 


October,  1921 


THE  ELECTRIC  JOURXAL 


437 


when  capital  finds  that  the  street  railway  business  is  on 
a  more  permanent  basis,  and  after  there  has  been  an 
uninterrupted  period  of  several  years'  favorable  earn- 
ings, it  will  again  become  an  attractive  field  for  the 
investor,  an  active  market  for  the  manufacturer  and  a 
more  satisfactory  and  attractive  field  for  the  operator. 


The  Development  of  Rapid 
Transit  Lines 

BRITTON  I.  BUDD, 

President,   Chicago  Elevated  Railroads 
And  Chicago  North  Shore  &  Milwaukee  Railroad 

IN  presenting  my  views,  some  consideration  will 
be  given  to  the  subject  of  electrification  of  steam 
railroads,  first  because  the  greatest  strides  in  elec- 
tric railroad  construction  in  the  next  decade  or  so  will 
be  in  that  branch  of  transportation,  and  secondly  be- 
cause the  electrification  of  the  steam  railroads  wdl 
have  a  decided  efifect  on  the  electric  railway  industry 
proper.  Most  people  consider  the  latter  as  somethii-ijj 
quite  distinct  from  electrified  steam  railroads,  but  im- 
doubtedly  the  two  will  become  more  closely  inter-con- 
nected as  time  goes  on.  The  views  here  expressed 
necessarily  are  those  of  one  more  acquainted  with  rail- 
road operations  in  and  adjacent  to  large  cities.  How- 
ever, there  are  certain  fundamental  thoughts  that  can 
be  applied  to  the  properties  in  small  towns  and  to  the 
lighter  interurban  properties. 

One  particular  outside  factor  must  be  taken  into 
account,  i.e.,  the  gasoline-propelled  vehicle  as  a  com- 
mon carrier  of  both  passengers  and  freight  operating 
in  our  city  streets  and  rural  highways.  Privately- 
owned  gasoline-propelled  vehicles  have  taken  consider- 
able trafiic  from  both  the  electric  and  steam  railroads, 
and  must  be  given  consideration  in  traffic  calculations. 

The  problem  of  the  transportation  man  will  be  to 
co-ordinate  the  electric  railway,  the  gasoline  carrier 
and  the  electrified  steam  railroad,  so  that  each  will  fit 
into  its  proper  place  and  perform  the  character  of  serv- 
ice for  which  it  is  best  adapted.  Common  ownership 
of  all  means  of  transportation  seems  neither  possible 
nor  desirable,  so  that  the  harmonizing  of  the  various 
factors  must  be  accomplished  through  proper  public 
regulation,  if  the  economic  waste  due  to  duplication  cf 
service  is  to  be  avoided  and  the  public  given  the  most 
efficient  service  possible  at  the  lowest  possible  cost. 

The  greatest  development  in  local  transportation, 
aside  from  the  electrifying  of  steam  terminals,  in  our 
large  cities  in  the  next  few  years  will  take  the  form 
of  rapid  transit  lines,  removed  from  the  surface  of  the 
streets,  rather  than  the  extensive  building  of  surface 
lines.  The  constantly  increasing  congestion  in  city 
streets,  due  to  the  use  of  the  gasoline-propelled  vehicle 
and  the  steadily  increasing  demand  of  the  public  for 
greater  speed  in  transit,  will  make  the  construction  of 
more  rapid  transit  lines  imperative.  This  development 
of  rapid  transit  lines  will  probably  be  in  the  nature  of 


subways  in  thickly  congested  city  areas  and  elevated 
railways  in  the  outlying  sections.  While  the  cost  of 
construction  of  both  subways  and  elevated  lines  neces- 
sarily will  be  high,  the  delays  occasioned  to  all  forms 
of  traffic  in  our  city  streets^,  if  measured  in  terms  cf 
dollars  and  cents,  will  compel  the  building  of  rapid 
transit  lines,  regardless  of  the  initial  cost. 

It  does  not  seem  probable  that  sufficient  private 
capital  will  be  found  to  finance  rapid  transit  lines  on 
the  scale  required  to  meet  the  demands  of  the  public. 
It  is  questionable  if  any  one  source  will  be  found  to 
finance  such  undertakings,  so  that  the  great  cost  of 
cotistruction  is  likely  to  be  met  partly  by  assessment 
on  the  property  directly  benefited,  partly  by  the  muni- 
cipality or  municipalities  in  which  the  lines  will  operate 
and  partly  by  private  capital.  With  the  growth  c-f 
rapid  transit  lines,  the  tendency  of  the  people  will  be 
to  live  farther  and  farther  from  the  congested  areas, 
so  that  the  local  transportation  companies  of  the  fu- 
tiu'e  will  be  required  to  give  a  service  similar  to  the 
suburban  service  now  supplied  by  the  steam  railroads 
and  by  interurban  electric  railroads. 

The  problem  of  electric  railways,  from  the  operat- 
ing standpoint,  is  to  utilize  their  track  investment  to  a 
greater  degree  than  is  now  being  done,  or  indeed,  than 
is  possible  under  existing  conditions.  More  people 
must  be  carried  per  mile  of  track  operated  with  less 
congestion  and  lower  operating  costs.  In  other  words, 
we  must  have  a  more  efficient  use  of  track  capacity. 
To  accomplish  this  it  may  be  found  necessary  to  aban- 
don certain  routes  and  to  use  other  routes  more  inten- 
sively by  means  of  trailers  or  double-deck  cars.  Also 
more  passengers  must  be  carried  per  unit  of  car  weight 
and  per  unit  of  platform  labor  than  at  present. 

The  question  of  whether  a  given  piece  of  track  is 
justified  or  not  will  certainly  be  brought  home  to  the 
operator  when  it  is  found  necessary  to  put  in  a  consid- 
erable amount  of  money  in  the  reconstruction  of  that 
piece  of  track.  It  may  be  that  the  car  operation  is 
efficient  and  economical  from  the  point  of  view  of 
maintenance  of  equipment,  power,  and  platform  labor, 
but  if  the  traffic  does  not  justify  a  sufficient  number  of 
car-miles  then  the  reconstruction  and  maintenance  of 
the  track  may  be  prohibitive,  in  which  case  it  should 
be  removed  and  the  service  abandoned  in  favor  of 
other  means  of  transportation.  A  considerable  num- 
ber of  loaded  car-miles  per  mile  of  track  is  required 
to  justify  the  cost  of  track  construction  or  reconstruc- 
tion. The  advantage  of  the  gasoline-propelled  vehicle 
or  trackless  trolley  is  apparent,  in  that  it  does  not  re- 
quire a  frequent  interval  service  in  order  to  pay  for 
a  heavy  investment  in  track.  Again,  if  a  given  route 
does  not  work  out  satisfactorily  financially,  another 
route  may  be  selected  without  losing  a  large  investment. 

It  may  safely  be  assumed  that  the  electrification  of 
steam  railroad  terminals  within  our  large  cities  will  be 
accomplished  within  a  few  years.  The  elimination  of 
the  dirt,   smoke,   cinders   and  noise,    inseparable    from 


43i 


THE  ELECTRIC  JOURNAL 


Vol.  XVIir,  No.  lo 


steam  locomotive  operation,  is  being  demanded  with  ni- 
creasing  insistence.  The  answer,  of  course,  is  electri- 
fication. The  problem  of  electrification  of  steam  rail- 
road terminals  is  less  serious  than  it  seemed  a  few 
}'ears  ago.  There  is  hardly  a  large  city,  where  tlie 
change  is  contemplated,  that  the  required  amount  oi 
power  cannot  be  furnished  by  the  local  central  station 
company  at  less  cost  than  the  railroad  could  produce  i!. 
The  increased  terminal  track  capacity  of  electric  oper- 
ation over  steam  operation  is  so  well  known  and  firmly 
established  that  it  is  not  necessary  to  discuss  it.  But 
unless  the  electrified  steam  railroads  giving  a  suburban 
passenger  service  are  co-ordinated  with  the  rapid 
transit  electric  lines  giving  a  similar  service,  the  in- 
creased terminal  track  facilities  may  easily  be  absorbed 
by  the  rapid  increase  in  suburban  traffic,  bringing  the 
steam  railroads  to  a  point  where  more  track  capacity 
must  be  secured  at  a  tremendous  expenditure  of 
capital,  in  order  to  provide  for  the  long  distance  trains. 
The  peak  of  through  train  and  the  peak  of  suburban 
train  traffic  is  often  co-incident.  Suburban  business 
has  been  unprofitable  and  probably  will  always  con- 
tinue to  be  so.  There  is,  however,  no  reason  why  the 
electrified  steam  railroads  should  not  use  the  rap'.d 
transit  line  tracks  as  entrances  into  cities,  at  lea.st 
for  some  of  their  trains.  They  should  further  make 
provision  for  diverting  their  suburban  business,  when 
il.  becomes  burdensome,  to  the  rapid  transit  lines  which 
are  there  primarily  to  perform  that  class  of  service. 

The  interurban  railroad  that  is  going  to  live  and 
prosper  must,  give  a  much  higher  class  of  service  than 
some  of  them  have  done  in  the  past.  The  type  of  m- 
terurban  which  is  built  on  highways  or  partially  on 
private  right  of  way  and,  due  to  engineering  faiills  or 
to  location,  is  unable  to  give  a  high-speed  first-class 
service,  will  sooner  or  later  have  to  be  improved  or 
scrapped.  The  public  has  become  educated  to  new- 
standards,  both  as  to  speed  and  comfort,  through  tlie 
use  of  the  automobile.  The  old-time  inferior  service 
given  by  some  interurban  roads  will  not  meet  the  needs 
of  the  public.  Particularly  is  this  true  where  such  in- 
terurban roads  are  in  competition  with  steam  lines  and 
paralleled  by  good  highways. 

The  gasoline-propelled  vehicle  of  today  is  in  a 
position  somewhat  similar  to  the  electric  street  car  in 
the  early  days.  That  its  development  will  follow  the 
lines  of  the  electric  railway  seems  probable.  Large 
operating  companies  will  be  organized  and  recognized 
as  public  carriers,  coming  under  the  same  public  regu- 
lation to  which  other  transportation  agencies  are  sub- 
ject. Qperating  costs  will  be  analyzed,  due  regard 
being  given  to  the  wear  and  tear  on  public  streets  and 
highways,  and  taxes  apportioned  accordingly.  When 
that  has  been  accomplished  and  the  gasoline-propelled 
vehicle  put  in  its  proper  place,  it  will  be  found  to  be 
a  valuable  adjunct  in  the  general  scheme  of  transporta- 
tion. But  the  gasoline-propelled  vehicle  must  be  a 
part  of  a  properly  co-ordinated  transportation  system 


and  not  an  independent  factor.  It  will  have  a  field  of 
its  own.  As  the  principal  function  of  the  steam  road 
must  be  the  long-distance  haul  of  both  passengers  and 
freight  and  the  chief  function  of  the  electric  rapid 
transit  line  the  intermediate-haul,  so  the  gasoline-pro- 
pelled vehicle  will  find  its  proper  place  in  the  short-haul 
traffic  field  for  both  passengers  and  freight. 

At  present,  the  gasoline-nropelled  vehicle  is  given 
considerable  advantage  over  the  electric  railwa' . 
The  public  pays  for  the  building  and  maintenance  of 
the  thoroughfare  over  which  it  operates,  so  that  such 
costs  are  not  a  charge  on  the  service  it  performs,  but 
that  condition  is  not  likel}"  to  last  as  the  business  be- 
comes more  fully  developed.  Placed  on  anything  like 
an  equal  footing  with  the  electric  or  the  steam  railroad, 
the  gasoline-propelled  vehicle  would  not  be  able  to 
compete,  except  on  very  short-haul  traffic.  It  will 
never  be  able  to  compete  successfully  with  the  electric 
car  operating  on  rails  for  long-distance  of  even  for  in- 
termediate-haul traffic. 

Thus  far  only  some  of  the  operating  features  ot 
the  electric  railway  have  been  touched  upon,  but  it 
might  be  well  to  glance  at  the  financial  side  of  the  in- 
dustry', which  has  been  the  most  serious  part  of  the 
question  for  a  number  of  years.  Although  the  indus- 
try is  by  no  means  out  of  the  woods  in  a  financial  way, 
probably  the  most  critical  period  has  been  passed. 

The  strangle-hold  of  the  five-cent  fare  fetich, 
which  in  recent  years  has  driven  so  many  electric  rail- 
way companies  into  receivership  has  been  broken  and, 
while  office-seeking  politicians  and  circulation-seeking 
yellow  newspapers  occasionally  clamor  for  the  restora- 
tion of  that  strangle-hold,  the  great  mass  of  the  peopli- 
have  come  to  take  a  moi'e  reasonable  and  intelligent 
view  of  the  situation  than  they  ever  had  before.  The 
people  realize  more  clearly  that  electric  railway  service 
is  a  necessity  in  their  daily  lives  and  that  the  charge 
for  such  service  must  be  based  on  what  it  costs.  The 
watchword  of  the  electric  railway  companies  must  be 
"Service,"  for  it  is  service  that  the  public  demands. 
If  the  public  is  given  the  right  character  of  service,  't 
will  be  found  willing  to  pay  a  fair  and  reasonable  price 
for  that  service. 


Futures 

CALVERT  TOVVNLEY 

.Assistant  to  the  President 
Wcstinghouse  Electric  &  Mfg.  Company 

THERE  is  much  speculation  as  to  the  future  of 
the  electric  railroads.  Having  formerly  been 
profitable  enterprises  and  as  a  class  being  so  no 
lont^er,  those  interested  wonder  whether  electric  rail- 
way securities  will  continue  on  the  down  grade  or 
whether  they  will  come  back. 

In  the  beginning,  when  the  electric  motor  dis- 
placed the  street  car  mule,  it  offered  to  the  public  a 
fundamental  advantage  of  tremendous  value,  i.  e. 
greatly  increased  speed  of  transportation.     The  trolley 


October,   1921 


THE  ELECTRIC  JOURNAL 


439 


car  then  became  the  most  rapid  means  of  getting 
about  town  and  the  enterprising  pioneers  of  the  indus- 
try, being  unhampered  by  regulation,  soon  capitalized 
this  advantage  and  with  great  rapidity  built  up  a  tre- 
mendous industry  in  a  comparatively  short  period  of 
time.  Everyone  is  familiar  with  the  subsequent  decline 
of  the  industry  due  to  various  and  sundry  burdens  of 
increased  expense,  and  to  the  limitation  of  fares,  but 
along  with  this  change  came  another  and  more  funda- 
mental modification,  namely,  that  brought  about  by  the 
automobile. 

The  trolley  car  is  now  no  longer  the  speediest 
vehicle  for  urban  transportation.  In  fact  it  has  been  so 
far  surpassed  by  the  automobile  that  the  trolley  officials 
themselves  seldom  use  it  for  getting  about  over  their 
own  lines.  It  is  conceivable,  even  if  perhaps  unlikely, 
that  the  laws  prescribing  regulation  and  those  respect- 
ing certain  burdens  of  expense  may  be  so  modified  as 
to  leave  the  trolley  roads  unhampered  to  work  out  their 
own  salvation,  but  the  automobile  is  here  to  stay  and 
must  be  reckoned  with  as  a  permanent  competitor. 
This  competition  may  perhaps  be  broadly  subdivided 
into  four  classes, — 

I — The  jitney 

2 — The  organized  bus  line 

3 — The  taxical) 

4 — The  private  motor  car. 

The  jitney  seems  to  have  been  a  more  or  less  viru- 
lent disease  which  is  rapidly  running  its  course  because 
its  basis  of  operation  was  unsound.  That  is  to  say,  the 
jitney  was  originally  free  from  burdensome  legal  re- 
strictions and  in  addition  the  jitney  driver  did  not 
know  what  his  service  was  costing.  Although  the  jit- 
ney probably  will  never  be  altogether  eliminated,  street 
railway  men  as  a  class  undoubtedly  feel  that,  as  a  fatal 
trolley  disease,  this  pest  is  rapidly  fading.  Public 
;iuthorities  are  generally  coming  to  recognize  that,  for 
their  own  protection,  jitneys  should  be  treated  as 
common  carriers  and  therefore  subject  to  the  sarne 
control  as  other  common  carriers,  and  this  recognition, 
reinforced  by  the  firm  and  just  insistence  of  some 
trolley  companies  that  either  the  jitneys  be  controlled 
or-  they  themselves  would  go  out  of  business,  has 
brought  about  the  cure. 

Some  months  since  the  Electric  Raihvay  Journal 
published  a  series  of  articles  giving  statistics  compiled 
from  the  records  of  a  large  number  of  bus  companies, 
which  showed  anything  but  favorable  financial  results. 
While  bus  companies  will  no  doubt  continue,  and  while 
the  bus  has  a  distinct  field  of  usefulness,  it  does  not 
possess  the  most  effective  weapon  which  other  motor 
cars  use  against  the  trolley,  i.e.  increased  speed.  It  is 
a  cumbersome,  lumbering,  slow  moving  affair,  which 
obstructs  traffic  more  than  other  passenger  vehicles,  is 
c]uite  inadequate  to  handle  heavy  traffic  and  moveover 
has  a  very  high  maintenance  and  operating  cost.  In 
view  of  these  facts,  it  seems  clear  that  the  fundamental 
handicaps  of  bus  service  will  prevent  it  from  ever  sub- 
stantially replacing  that  offered  by  the  trolley. 


The  taxicab  and  the  private  car  compete  on  an  en- 
tirely different  basis.  They  do  not  attempt  to  handle 
all  the  traffic.  They  do  not  attempt  to  compete  in 
price.  On  the  contrary  they  cater  entirely  to  those  who 
want  greatly  increased  speed  and  comfort  and  are  will- 
ing to  pay  accordingly.  Their  use  has  gone  forward 
by  leaps  and  bounds  and  there  is  little  doubt  but  that 
most  of  the  people  who  use  them  were  formerly  trolley 
car  patrons  and  would  still  be  if  the  present  facilities 
were  not  available. 

Admitting  this  permanent  depletion  in  trolley  pa- 
tronage and  recognizing  the  numerous  and  increasing 
number  of  private  cars  and  taxicabs,  it  is  still  an  un- 
doubtedly safe  assumption  that  this  number  will  never 
constitute  more  than  a  relatively  small  percentage  of 
the  total  population.  If  this  assumption  be  correct, 
then  all  the  changes  in  fundamental  conditions  enumer- 
ated above  still  leave  a  substantial  field  for  the  trolley. 

In  the  past  the  trolley  has  performed  two  distinct 
services  in  its  community.  First,  it  furnished  public 
transportation,  and  second,  through  the  medium  of  ex- 
tensions into  suburban  districts,  many  of  them  not  yet 
having  a  supporting  density  of  population,  it  induced  a 
migration  of  the  people  to  those  sparsely  settled  dis- 
tricts with  the  ultimate  result  of  municipal  extension, 
increased  taxable  values,  dilution  of  population  density 
in  the  centers  and  sometimes  incidentally  the  creation 
of  profitable  traffic  for  the  trolleys.  Regulation  has 
recognized  and  permitted  the  first  function  above  but 
has  taken  no  accormt  whatever  of  the  second,  conse- 
quently surburban  trolley  building  in  anticipation  of 
future  traffic  has  long  since  stopped. 

In  forecasting  the  future  of  the  trolleys,  there 
seems  to  be  little  probability  that  they  will  ever  again 
be  a  material  factor  in  city  extension.  The  necessity 
for  their  existence  as  already  established  may,  and 
probably  will  be,  sufficiently  appreciated  to  secure  laws 
that  will  permit  an  interest  yield  that  will  make  their 
securities  reasonably  safe  for  investors,  but  without 
any  chance  for  handsome  profits.  Without  this  chance 
capital  will  not  take  the  risk  involved  in  building  ahead 
of  the  demand.  We  may  expect  to  approach  more  and 
more  nearly  to  the  situation  which  has  existed  for  a 
long  time  in  England,  where  the  trolleys  are  operated 
only  through  congested  districts,  where  they  are  seldom 
if  ever  extended,  and  where  they  are  gradually  but 
surely  becoming  less  and  less  of  a  factor  in  the  total 
transportation  problem. 


The  Trackless  Trolley  or  Trolley  Bus 

THOS.  S.  WHEELWRIGHT, 

President. 
Virgrinia  Railway  &  Power  Company 

SINCE  July  I,  successful  demonstrations  of  the 
trackless  trolle}^  have  been  made  in  Richmond 
and  Norfolk,  Virginia,  in  the  smooth-paved  resi- 
dential districts  where  the  right  to  operate  track  lines 
has    been    denied.       During    the    demonstrations,    the 


440 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.   lo 


public  as  well  as  public  officials  of  these  two  cities 
were  most  generous  in  their  approval  of  this  new 
method  of  transportation.  In  their  references  to  the 
new  trollibus,  many  of  its  enthusiasts  have  carelessly 
remarked  that  it  is  a  revolution  of  the  present  street 
railway  system — which  is  all  wrong.  It  is  an  evolu- 
tion; not  a  revolution!  Note  the  definitions  given  of 
the  two  terms  by  the  Standard  Dictionary : — 

Evolution:  The  act  or  process  of  evolving;  de- 
velopment or  growth,  as  the  evolution  of  a  plan  or  sys- 
tem. 

.  Revolution  :  An  extensive  or  radical  and  usually 
somewhat  sudden  change  in  anything.  A  movement 
involving  the  overthrow  or  repudiation  of  an  existing 
government,  etc. 

It  will  be  noted  that  evolution  connotes  growth 
and  development  whereas  revolution  suggests  destruc- 
tion by  radical  change,  repudiation  or  overthrow. 
Therefore,  applying  these  definitions,  it  will  be  seen 
that  the  trackless  trolley  or  trolley  bus  is  an  evolution 
rather  than  a  revolution.  It  is  a  means  for  the  devel- 
opment of  the  present  street  railway  system,  whereby 
transportation  service  can  be  made  to  grow  and  expand 
with  the  development  of  the  community.  The  use  of 
the  term  "revolution"  in  connection  with  the  trackless 
trolley  has  already  fixed  in  the  minds  of  some  the  idea 
of  destruction  because  frequently  the  question  is  asked 
whether  the  company  plans  to  pull  up  its  present  tracks 
and  substitute  trackless  transportation. 

Neither  Richmond  nor  Norfolk,  nor  any  other 
city,  is  much  concerned  about  changing  the  mode  of  its 
transportation  where  it  already  exists.  What  con- 
cerns, or  rather  what  should  concern,  ever}-  growing 
community  is  how  to  keep  the  transportation  lines  it 
already  has  and  how  to  get  service  into  those  sections 
not  now  served.  That's  what  concerns  these  Virginia 
cities. 

Like  the  evolution  of  street  paving  from  cobble- 
stone to  Belgian  block  and  from  Belgian  block  to 
asphalt  and  concrete,  so,  too,  must  there  be  an  evolu- 
tion of  transportation  and  other  facilities  to  meet  the 
modern  need.  The  electric  street  railway  is  in  keeping 
with  the  stone  and  other  rough  paving,  because  both 
connote  noise.  With  the  smooth-paving,  however, 
comes  the  demand  for  a  transportation  service  that  will 
be  in  keeping  with  the  quiet  and  comfort  suggested  by 
the  new  smooth  paving.  To  meet  this  demand  and  de- 
sire, the  trolley  bus  has  been  especially  designed  for 
operation  in  those  smooth-paved  sections  where  regular 
transportation  service  is  not  now  available.  Its  func- 
tion will  be  to  reach  out  into  those  unserved  sections. 

Thus  the  trolley  bus  is  an  evolution  or  develop- 
ment, not  a  revolution  or  overthrow.  It  is  a  means  by, 
which  the  electric  trolley  can  be  made  a  greater  factor 
in  community  growth  of  the  future  than  it  has  ever 
been  in  the  past. 


Outlook  for  the  Electric  Railway 
Industry 

HENRY  A.  BLAIR, 

Chairman   Board  of   Operation, 
Chicago  Surface  Lines 

THE  ELECTRIC  railway  is  the  public  ,->er\ice 
facility  most  intimately  connected  with  the 
everyday  life  of  urban  inhabitants  of  die  L  iiiied 
.States.  The  necessity  for  its  continued  operation  is 
paramount  in  importance.  When  local  interruption  of 
the  service  occurs  in  marked  degree,  it  has  a  paralyzing 
effect  upon  the  economic,  social  and  industrial  life  of 
the  community,  and  when  from  any  cause  these  inter- 
ruptive  conditions  against  the  normal  functioning  of 
this  essential  service  become  general,  the  paralyzing 
effect  extends  to  the  economic,  social  and  industrial 
life  of  the  nation. 

Development  of  the  street  railway  business  of  the 
country  has  been  gradual  from  small  beginnings  with 
slow  moving,  diminutive  vehicles  drawn  by  a  single 
horse  to  larger  two  horse  cars,  then  the  faster  cable 
railway  with  larger  and  better  cars  operated  in  trains, 
and  finally  the  now  highly  perfected  electric  railway 
systems  requiring  a  capital  expenditure  per  mile  of 
track  more  than  eight  times  the  investment  retiuired 
to  produce  the  original  horse  car  lines,  and  supplying 
rides,  until  quite  recently,  for  the  same  unit  fare  for 
distances  ten  times  greater  than  the  maximum  distance 
traveled  by  the  horse  car. 

In  the  early  days  of  promotion  in  the  street  rail- 
way business,  those  men  of  vision,  courage,  and  the 
ability  to  actualize  their  conception  of  a  useful  public 
service,  were  looked  upon  as  public  benefactors;  they 
were  given  encouragement  and  co-operation  of  the 
communities  where  local  transportation  was  proposed 
and  from  small  beginnings  the  development  of  the 
.service  and  expansion  of  the  communities  were  rapid. 
In  the  beginning,  after  the  demand  for  service  became 
sufficient  to  establish  the  necessity  for  the  street  rail- 
way and  signs  were  evident  that  the  business  was  or 
would  become  commercially  profitable,  competing 
companies  were  organized  and  obtained  operatinc 
rights  in  the  same  community  in  almost  all  place-; 
where  street  railways  had  been  installed. 

Urban  transportation,  being  a  natural  monopoly, 
the  consequences  of  duplication  of  service,  duplication 
of  investment  and  operating  expenses  soon  began  to 
contract  the  margin  between  income  and  outgo  to  an 
extent  that  threatened  financial  disaster  to  the  indus- 
try. Then,  in  obedience  to  that  natural  law  of 
monopoly  in  public  service  and  in  order  to  remove  the 
danger  which  then  threatened  the  business,  managers 
of  street  railways  sought  the  safe  haven  of  consolida- 
tion of  the  competing  lines  so  that  the  business  might 
be  conducted  in  harmony  with  a  sane  plan  of  progres- 
sion and  in  the  best  interest  of  the  public  and  the  op- 
erating corporations. 

Through  the  process  of   consolidation  of  compet- 


October,  1921 


THE  ELECTRIC  JOURNAL 


441 


ing  companies  and  the  expansion  of  the  railway  sys- 
tems, the  companies  naturally  became  larger  and 
larger,  and  the  capital  represented  by  these  operations 
involved  many  millions  of  dollars.  As  the  communi- 
ties expanded  in  population  and  area,  the  inhabitants 
became  more  and  more  dependent  upon  the  services 
rendered  by  the  street  railway  companies  and,  as  these 
consolidated  public  service  interests  increased  in  mag- 
nitude and  power,  a  field  of  exploitation  was  opened 
and  invaded  by  unscrupulous  promoters  whose  sole 
aim  was  the  making  of  quick  money,  and  by  self-seek- 
ing, political  interests  who  saw  an  opportunity  for 
political  advantage  in  advocating,  in  the  name  of  the 
people,  unreasonable  demands,  and  creating  public 
prejudice  against  the  service  corporations — all  of 
which  resulted  in  vital  restriction  of  the  rights  and 
privileges  of  these  operating  companies,  i.  e.,  limited 
franchises,  fixed  fares,  free  transfers,  the  imposition 
of  unjust  burdens  in  the  form  of  obligations  to  per- 
form services  of  a  public  character  which  are  distinctly 
functions  of  municipal  government.  These  arbitrary 
restrictions,  in  addition  to  the  constantly  increasing 
cost  of  labor  and  materials,  taken  in  connection  with 
the  inelastic  fare  requirements  of  franchises  had,  prior 
to  the  recent  world  war,  created  a  financial  situation 
in  the  street  railway  business  that  weakened  the  credit 
of  the  companies  and  made  it  difificult  for  them  to  raise 
the  money  constantly  required  for  extensions  and  im- 
provement of  service,  except  at  costs  in  the  form  of  in- 
terest rates  and  discounts  that  were  rapidly  approach- 
ing the  prohibitive  stage. 

Then  came  the  world  war  with  the  accompanying 
\iolent  increases  in  the  cost  of  every  element  entering 
into  the  expense  side  of  conducting  street  railway 
affairs  without  any  compensating  increase  in  the  rates 
charged  for  service.  As  a  result  net  earnings  of  the 
traction  companies  fell  off  and  their  already  weakened 
credit   was   almost   totally   destroyed.     Capital    had   to 

•  be  secured  to  take  care  of  maturing  obligations  and,  as 
the  margin  of  safety  over  interest  requirements 
diminished,  the  risks  attending  investments  in  railway 
securities  increased,  and  the  companies  have  had  to 
oft'er  greater  and  greater  inducements  to  attract  neces- 
sary new  capital  which  could  be  secured  only  at  in- 
terest rates  in  many  instances  higher  than  the  fixed  rate 
of  return  allowed  on  the  investment  by  franchise  and 
other  regulations. 

During  the  last  two  years,  some  measure  of  relief 
has  been  obtained  through  orders  of  State  Public  Utili- 
ties Commissions,  who  have  advanced  rates  after  thor- 
ough investigation  nf  the  facts.  These  advances  in 
rates,  though  helpful,  have  not  altered  the  situation  in 
regard  to  the  lost  credit  of  the  street  railway  com- 
panies of  the  United  States.  Upon  a  proper  solution 
of  this  question  of  credit  rests  the  prosperity  of  the 

■    business  and  the  adequacy  of  the  service  to  the  public. 

The   problems   confronting  the   street   railway   in- 

dustr\'  are,  in  the  last  analysis,  problems  of  the  people. 

Their  solution  depends  upon  a  complete  understanding 


by  the  public  of  these  problems  as  they  now  exist  and 
the  education  of  the  people  to  the  importance  of  the 
(juestions  to  be  solved  and  the  method  of  curing 
them.  The  prime  factors  in  the  solution  of  these  prob- 
lems are  therefore : — 

First,  the  creation  of  a  sound  and  correct  public 
sentiment  with  the  eradication  of  a  number  of  ideas 
that  have  come  down  from  the  past  in  the  way  of  pre- 
judices, such  as,  the  belief  that  the  industry  considered 
as  a  whole  is  greatly  over-capitalized  and  that  the 
people  are  asked  to  pay  return  on  excess  capitaliza- 
tion, and  that  the  present  situation  of  the  companies  is 
the  result  of  mismanagement  or  dishonesty. 

Second,  recognition  that  the  street  railway  busi- 
ness must  be  solved  on  the  basis  of  service  and  that 
there  are  mutual  obligations  on  the  part  of  the  service 
companies  and  the  public — on  the  part  of  the  com- 
panies to  render  good  service  under  proper  and  sane 
public  regulations,  on  the  part  of  the  public  to  provide 
the  revenue  that  will  pay  all  the  costs  of  the  service, 
including  a  fair  return  upon  the  fair  value  of  the 
property  used  and  useful  in  rendering  that  service  to- 
gether with  the  necessar}-  reserve  funds  to  insure  the 
upkeep  of  the  utility. 

Rates  established  on  the  fair  value  of  the  property 
bear  no  relation  to  the  amount  of  capitalization.  Spe- 
cial and  earnest  effort  is  required  on  the  part  of  rail- 
way officials,  state  public  utilities  commissions  and  the 
courts  to  evolve,  as  nearly  as  can  be,  uniform  methods 
for  determining  the  fair  value  of  public  utilities  for 
rate  making  purposes  and,  where  the  capitalization  of 
companies  exceeds  the  fair  value  as  determined,  re- 
adjustments should  be  undertaken  to  bring  the  par 
value  of  outstanding  securities  as  near  to  the  level  of 
the  established  fair  value  as  possible.  Future  exten- 
sions should  be  financed  partially  through  the  sale  of 
stocks  to  create  and  maintain  a  constantly  increasing 
margin  between  the  outstanding  mortgage  .securities 
and  the  established  fair  value  of  the  properties. 

That  the  essential  public  service  supplied  by  the 
street  railways  must  be  continued  is  obvious.  Unless 
there  is  established  complete  co-operation  between  the 
public  and  the  privately-operated  utility  looking  to  the 
rehabilitation  of  the  credit  of  the  operating  companies 
on  some  sound  cost-of-service  basis,  these  street  rail- 
ways will  not  be  able  to  function  properly  and  the 
alternative  of  public  ownership  and  operation  of  them 
must  be  resorted  to  and  all  the  costs  of  the  service  be 
provided  directly  through  fares  or  indirectly  through 
taxes.  There  can  be  no  doubt  as  to  which  of  tKese 
alternatives  is  economically  sound  and  will  be  adopted 
by  any  correctly  informed  community. 

Where  cost-of-service  contracts  have  been 
adopted,  good  service,  a  fair  wage  to  employes,  a  fair 
return  on  capital  and  established  credit  have  resulted. 
There  is  no  single  cost-of-service  plan,  which  in  its 
entirety  can  be  applicable  to  every  company  or 
locality,  or  to  all  conditions.     However,  there  are  cer- 


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THE   ELECTRIC   JOURNAL 


Vol.  XVIir,  No.  lo 


tain  fundamental  principles  that  will  apply  to  almost 
every  case  and  in  so  far  as  they  are  applicable  the 
problems  of  the  different  localities  and  companies  are 
alike  and  details  that  will  harmonize  with  these  funda- 
mentals and  will  fit  the  local  situation  in  each  case, 
are  entirely  susceptible  of  being  worked  out  and, 
therefore,  the  general  applicability  of  the  cost-of-serv- 
ice  plan  may  be  recognized. 

Fundamentals  that  should  underlie  every  cost-of- 
service  plan  are;  indeterminate  franchises,  which  re- 
serve to  the  city  the  right  of  purchase ;  adequate  public 
regulation  supervising  the  service  and  safe-guarding 
the  rights  of  the  public ;  automatic  adjustment  of  rates 
as  the  cost  of  the  service  fluctuates  upward  or  down- 
ward; establishment  of  necessary  reserve  funds  and  a 
fair  return  upon  a  fair  valuation  of  the  property  with 
some  additional  return  dependent  upon  efficiency  of 
management  in  keeping  fare  rates  as  low  as  possible. 
Contracts  based  upon  these  fundamental  requirements 
will  insure  good  service  and  will  establish  and  main- 
tain the  credit  of  the  corporations,  place  the  securities 
of  street  railways  in  a  position  that  will  make  them 
desirable  as  permanent  investments  and  enable  the 
companies  to  obtain,  at  a  reasonable  cost,  the  large 
sums  of  money  that  are  required  for  capital  invest- 
ment to  keep  pace  with  the  yearly  demand  for  in- 
creased facilities  and  service. 

If  the  public  is  to  be  supplied  with  the  quality  of 
street  railway  service  to  which  it  is  entitled,  the  com- 
panies must  be  placed  in  a  position  which  will  enable 
them  to  go  into  the  market  and  compete  for  the  capital 
required  to  make  extensions  to  their  lines  and  provide 
the  necessary  equipment  and  other  physical  property. 
There  is  every  reason  to  believe  that  the  period  of 
tight  money  in  which  the  demand  for  capital  will  ex- 
ceed the  supply,  which  must  be  reflected  in  high 
charges  for  it,  will  be  further  prolonged.  Investors 
cannot  be  coerced  into  putting  their  money  into  enter- 
prises that  do  not  offer  a  substantial  degree  of  safety 
and  future  promise.  In  its  present  situation,  the  street 
railway  industry  does  not  offer  that  degree  of  safety 
and  future  promise  that  will  attract  capital.  However, 
though  a  spirit  of  gloom  has  prevailed  in  the  situa- 
tion during  the  recent  period  of  depression  and  of  sore 
trial  with  which  the  public  service  enterprises  through- 
out the  country  have  been  forced  to  contend,  the  out- 
look points  to  optimism  rather  than  to  pessimism. 

There  can  be  no  prosperity  without  local  trans- 
portation. The  inherent  good  judgment  of  the  people 
will  prevail  when  all  the  essential  facts  regarding  the 
st*-eet  railway  situation  has  been  revealed  to  them. 
Then  the  utility  companies  w^ill  be  accorded  the  co- 
operation of  the  public  in  bringing  about  a  readjust- 
ment of  street  railway  affairs  that  will  be  fair  to  both 
sides,  stabilitating  the  credit  of  the  service  companies 
to  the  end  that  good  service  will  be  given  to  the  public, 
fair  wages  to  employes,  and  insurance  of  a  fair  return 
on  invested  capital  until  it  shall  be  returned  to  its 
owners. 


Dealing  with  the  Public  and 
Employees 

HARRY  REID 

President, 
Interstate  Public  Service  Co.,  Indianapolis 

THE  EXECUTIVE  of  a  utility  who  would  serve 
the  public  satisfactorily,  has  three  interests  to 
consider, — the  invested  capital,  the  public  and 
the  employee.  The  success  of  his  company  depends, 
entirely  on  the  co-ordination  of  the  tliree.  The  follow- 
ing discussion  deals  with  only  two  of  these  subjects, 
the  public  and  the  employee. 

In  the  development  of  the  utility  business,  the 
minds  of  the  executive  and  operating  departments 
must  constantly  give  serious  thought  to  the  matter  of 
dealing  with  the  public  and  employees.  The  utility 
business  is  a  natural  monopoly  and  must  be  such  to 
serve  the  public  at  the  lowest  possible  rates  consistent 
with  good  service.  It  is  a  simple  mathematical 
proposition  that  a  duplication  of  investment,  brought 
about  by  competition,  will  add  additional  burdens  on 
the  public  in  higher  rates  to  maintain  the  same.  While 
the  method  employed  in  dealing  with  either  the  public 
or  the  employee,  in  a  general  way,  is  very  much  the 
same,  yet  these  are  two  distinct  problems. 

The  problem  of  dealing  with  the  public,  with  re- 
spect to  the  operation  and  maintenance  of  a  utility  in 
a  community  or  communities,  as  the  case  may  be,  is 
not  at  all  perplexing.  As  in  any  other  business,  truth- 
ful dealing  is  the  cardinal  principle.  In  order  to  be 
always  truthful  in  our  dealing  with  the  public,  patience, 
tact  and  a  thorough  knowledge  of  our  own  business 
and  the  principles  involved  are  required.  The  success- 
ful operator  of  a  utility  must  not  only  be  thoroughly 
trained  in  his  particular  field,  but  he  must  have  a  thor- 
ough knowledge  of  the  community  served,  a  broad  per- 
sonal acquaintance  with  the  territory,  a  general  knowl- 
edge of  the  particular  problems  peculiar  to  the  terri- 
tory served  and  keep  in  mind  that  the  solution  of  his 
problem  is  the  solution  of  the  community's  problem. 

Service  rendered  the  community  should  be  as 
nearly  perfect  as  it  is  possible  to  make  it  by  human 
effort.  The  handling  of  complaints  is  a  very  delicate 
part  of  our  business.  To  that  official  or  employee  dele- 
gated to  handle  complaints  is  also  entrusted  a  grave  re- 
sponsibility with  respect  to  the  success  of  the  property 
involved.  A  trivial  complaint  coming  from  the  least 
influential  person  in  a  community  can  be  likened  to  a 
snowball  rolled  by  a  school  boy.  As  the  complaint  is 
carried  from  one  person  to  another,  it  gathers  volume 
and  grows  larger  and  larger  and,  like  the  snowball, 
finally  becomes  unmanageable.  Perhaps  the  most  per- 
plexing problem  is  the  diplomatic  handling  of  com- 
plaints. How  easily  a  telephone  complaint  from  some 
outlying  district  can  become  general,  augmented  as  it 
will  be,  by  unfair  critics  and  criticism.  Utilities  gen- 
erally do  not  attach  enough  importance  to  their  com- 
plaint departments  in  the  employment  of  broadminded^ 


October,  1921 


THE   ELECTRIC  JOURXAI. 


443 


tactful  students  of  human  nature.  Many  very  serious 
complaints,  which  finally  reach  the  governing  body  of 
utilities,  the  public  service  commission  or  city  council, 
begin  in  a  very  small  way  and,  as  a  result  of  being 
treated  as  inconsequential  or  of  being  neglected  by  the 
service  department,  become  highly  aggrevated  expres- 
sions of  popular  dissatisfaction. 

No  utility  can  continue  popular  with  the  people  it 
serves  or  prosper  financially  without  an  open,  fair- 
minded  policy  in  its  dealings.  The  public  is  beginning 
to  learn  its  lesson  with  reference  to  utilities.  The 
value  of  property  in  any  community,  for  instance,  is 
very  largely  affected  by  the  kind  of  utilities  which 
serves  it  and  the  value  to  the  community  can  only  be 
measured  by  the  utility's  ability  to  serve  it.  The  public 
is  also  learning  its  lesson  with  reference  to  improve- 
ments and  cost  of  operation.  It  can  be  said  safely 
that  the  utilities  of  America,  generally  speaking,  serve 
the  public  with  better  service  at  less  cost  than  in  any 
other  country  in  the  world.  In  the  past,  utilities  have 
tried  to  serve  the  public  in  spite  of  unfair  conditions 
and  they  have  been  handicapped  b}'  rates  that  were  not 
in  keeping  with  the  value  of  the  service. 

Out  of  the  great  world's  war,  we  have  gleaned 
some  very  valuable  lessons,  and  one  of  these  lessons  is 
the  value  of  the  service  of  the  public  utility  in  any 
given  community.  Two  of  the  great  problems  of  the 
utility  operator  today  are  to  produce  service  for  a  fair 
return  and  to  educate  the  community  regarding  the 
value  of  the  service  given. 

There  is  no  general  cure  for  utility  troubles. 
Each  community  must  be  dealt  with  individually  with 
specific  attention  given  to  its  peculiar  topography. 
The  whole  situation  can  be  summed  up  by  saying  that 
utilities  may  be  successful  if  they  will  practice  open, 
fair-minded  dealing  with  the  community  served, 
thereby  educating  their  customers  in  the  problems  of 
the  company  and  especially  in  the  importance  of  the 
benefits  enjoyed. 

The  second  phase  of  this  question  is  that  of  deal- 
mg  with  the  employees.  Years  ago  we  had  a  Presi- 
dent whose  hobby  was  duck  hunting.  A  very  close 
friend  of  Mr.  Cleveland,  in  commenting  on  his  fond- 
ness for  hunting  said  he  was  unable  to  understand  how 
any  one  could  derive  any  pleasure  from  wading 
through  marshy  swamps  in  cold,  biting  winds,  being 
upset  in  muddy  water  from  a  canoe,  returning  at  night 
cold,  wet  and  hungry.  The  late  President  listened 
patiently,  as  his  friend  pointed  out  all  the  disagreeable 
experiences  incidental  to  duck  hunting,  and  after  the 
friend  had  concluded  his  argument,  Mr.  Cleveland, 
with  sparkling  eyes,  replied— "Jim,  duck  hunters  are 
like  artists,  they  are  born,  not  made."  This  particular 
story  is  apropos  of  the  utility  employee  of  today— he 
IS  born,  not  made.  In  taking  new  blood  into  an  or- 
ganization, care  should  be  given  to  fix  in  the  mind  of 
the  employee  the  peculiar  problems,  perplexities  and 
duties  which  are  automaticallv  assumed. 


Employees  of  utilities,  from  the  lowest  in  rank  to 
the  highest,  no  matter  what  particular  place  they  may 
occupy  in  the  organization,  are  servants  of  the  public. 
As  servants  of  the  public,  we  owe  the  public  a  duty, 
as  well  as  the  corporation  we  serve.  In  the  selection 
of  employees,  or  the  replacing  of  employees  of  a 
utility,  extreme  care  should  be  given  to  personal  fit- 
ness; to  filling  their  minds  with  the  important  fact  that 
they  are  public  servants  and  can  materially  add  to  the 
success  of  their  employers;  that  their  actions  are  re- 
garded by  the  public  as  the  immediate  and  direct  re- 
flection of  the  policies  of  the  coi-poration. 

In  today's  game  of  life,  the  problem  of  getting 
ahead  in  the  world  is  as  perplexing,  and  perhaps  more 
so  than  at  any  other  time  in  world's  history.  Men  with 
ability,  who  enter  the  service  of  an  up-to-date  wide- 
awake utility  organization,  may  always  find  room  at  the 
top.  A  policy  of  open,  fair-minded  dealing  is  appli- 
cable to  the  employee,  as  well  as  to  the  employer.  The 
employee,  however,  should  be  impressed  with  the 
seriousness  of  the  duties  he  undertakes.  A  wage 
should  be  paid  employees  that  is  in  keeping  with  the 
service  they  are  to  perform.  Many  great  organiza- 
tions of  this  countiy  have  been  built  up  by  training 
their  own  men  and  this  is  particularly  true  of  trans- 
portation companies.  The  training  of  men  involves 
years  of  careful  selection,  patience  and  tact,  and  great 
care  should  be  given  to  the  promotion  of  trained  em- 
ployees to  better  positions  created  or  made  vacant  from 
various  causes.  Public  service  corporations  can  only 
be  successful  to  the  extent  that  they  are  represented  bv 
trained,  efficient  men. 


The  Relation  of  the  Electric   Railway- 
to  the  Community 

ARTHUR  W   THOMPSON 

President,  Philadelphia  Companv 
Pittsburgh,   Pa. 

It  has  been  zvell  said  Ikat  transpor- 
lation  is  the  measure  of  eivilization. 

PROGRESS  under  our  form  of  government  is 
based  on  the  idea  of  individual  liberty  which 
recognizes  limitations  to  individual  freedom  re- 
quired by  the  general  welfare.  The  printing  press, 
the  telegraph,  the  telephone,  mail  service,  the  moving 
picture,  have  all  pla3-ed  their  important  parts  in  mak- 
ing clear  the  necessity  for  subordinating  individual  de- 
sires to  the  general  welfare.  But  passenger  transpor- 
tation, which  provides  one  of  the  most  effective  means 
of  approaching  human  understanding  in  the  most  di- 
rect way — by  personal  contact  between  individuals  and 
groups — has  done  more  than  all  of  these  to  promote 
the  sound  development  of  our  country  until  it  has  ber 
come  the  best  living  place  for  the  individual,  and  there- 
fore the  most  powerful  and  prosperous  nation  on  earth. 
If  some  of  us  occasionally  contemplate  our  past 
performances  and  present  power  with  complete  satis- 
faction we  will  not  remain  complaisant  for  long.     Our 


444 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  10 


progress  has  been  due  to  an  increasing  knowledge  of 
affairs  which  affect  the  welfare  of  the  average  citizen 
and  he  is  not  going  to  continue  satisfied  with  his  pres- 
ent condition.  He  understands  that  real  improvement 
in  his  own  affairs  is  directly  dependent  upon  the  gener- 
al welfare,  and  he  is  going  to  insist  that  others  conduct 
themselves  in  accordance  with  the  general  welfare. 

Industrial  Development  and  Overcrowding — 
Along  with  passenger  transportation  development  has 
come  the  crowding  of  industrial  activities  and  popula- 
tion into  .small  areas.  The  member  of  society  upon 
whom  civilization  depends  for  its  existence,  the  work- 
er, has  the  most  vital  interest  in  the  results  of  this 
overcrowding.  By  worker  is  meant  one  who  does  use- 
ful manual  or  mental  work.  Nearly  everyone  comes 
within  this  class.  The  average  worker  knows  that  by 
reasonably  wise  political,  social  and  industrial  leader- 
ship, his  interests  are  served  reasonably  well. 

This  knowledge  on  his  part  and  the  actual  condi- 
tions surrounding  him,  which  everyone  must  admit  are 
not  reasonably  good  for  large  numbers  of  workers, 
make  imperative  some  action  to  provide  the  opportuni- 
ty at  least  for  the  worker  to  improve  his  condition. 
Most  leaders  of  men  realize  that  by  providing  broad 
opportunities  for  the  betterment  of  the  worker,  they 
are  best  serving  their  own  interests. 

Leadership — Pauperizing  efforts,  making  it  appear 
that  progress  in  improvement  can  be  made  only 
through  the  gracious  bounty  of  the  leaders,  does  more 
harm  than  good.  Honest  efforts  of  real  leaders  to  es 
tablish  organizations  for  the  betterment  of  workers  on 
sound  economic  foundations  have  helped  considerably 
in  some  cases,  but  taking  into  account  the  requirements 
of  the  general  situation,  the  results  of  these  efforts; 
have  been  comparatively  meager. 

Knowledge  is  power;  the  average  worker  is  gain- 
ing more  knowledge  of  matters  which  affect  his  inter 
ests  every  day.  Therefore  he  is  becoming  more  pow- 
erful in  those  affairs.  The  more  knowledge  he  gains, 
the  greater  is  his  ability  to  secure  wise  leadership  and 
steadv  improvement  in  his  present  condition.  The 
average  worker  may  not  understand  how  his  condition 
can  be  improved,  but  he  knows  when  his  leaders  are 
honestly  trying  to  keep  in  step  with  progressive  de- 
velopment; and  he  is  going  to  change  leadership  until 
he  secures  leaders  who  are  \vise  enough  to  recognize 
that  their  best  interests  lie  in  his  progressive  improve- 
ment. By  leaders  is  meant  men  who  are  in  positions 
of  influence  over  capital,  labor,  society  or  politics. , 

The  Home  and  Social  Progress — It  is  generally 
recognized  that  the  home  is  the  foundation  of  the  na- 
tion. The  average  worker  wants  a  good  home  for  hi? 
family  and  himself,  and  is  willing  to  work  for  it.  A 
careful  survey  of  the  conditions  existing  in  any  of  our 
large  industrial  centers  will  convince  anyone  that  some 
radical  change  must  be  made  in  the  living  conditions  of 
a  great  many  workers,  and  also  that  improvement  in 
these  conditions  is  going  to  increase  the  value  of  the 
worker  and  his  family  to  industry.       This  brings  us 


up  to  the  question  of  how  to  provide  for  the  improve- 
ment of  the  home  on  a  sound  economic  basis  by  a 
method  which  will  yield  a  fair  return  for  the  time, 
effort  and  money  expended  on  it.  Attempting  to  give 
something  for  nothing  or  to  get  something  for  nothmg 
can  lead  only  to  failure. 

Co-operation — The  answer  seems  obvious.  There 
are  practically  unlimited  areas  of  splendid  residence 
territory  within  electric  railway  distance  of  our  large 
industrial  centers.  No  one  of  the  elements  interested, 
the  employer,  the  community  or  the  car  rider  can,  by 
itself,  support  the  cost  of  building  and  operating  the  fa- 
cilities necessary  to  provide  the  opportunity  for  better 
homes.  All  elements  are  so  greatly  benefited  that  car- 
rying the  burden  by  any  one  of  them  means  giving 
something  for  nothing.  In  many  instances  the  employ- 
er is  trying  to  improve  conditions  by  providing  better 
houses ;  but  better  houses  in  the  same  locations  will  not 
always  answer,  and  better  houses  in  better  lo- 
cations without  the  necessary  transportation  to  make 
them  available  is  no  improvement.  The  employer 
must  go  a  step  farther  and  co-operate  with  the  com- 
munity and  the  car  rider  to  provide  better  homes  with 
the  necessary  transportation,  and  in  that  way  increase 
the  value  of  the  worker,  of  the  community  and,  there- 
fore, of  his  own  business. 

Essential  Nature  of  Street  Raihvays- — No  facility 
has  been  developed  which  can  compare  with  the  elec- 
tric railway  in  economy  and  comfort  for  hauling  large 
numbers  of  people  for  comparatively  long  distances. 
Some  other  kind  may  be  developed,  but  our  problems 
are  pressing  for  action  and  it  is  imperative  that  we  pro- 
ceed on  the  basis  of  our  present  knowledge  and  not 
wait  in  the  hope  that  something  better  may  turn  up. 
The  auto  bus  will  undoubtedly  develop  as  an  ally  of 
urban  transportation  systems,  but  the  backbone  of  any 
such  system  in  large  communities  must  be  the  electric 
railway. 

While  the  homing  instinct  is  going  to  be  the  prin- 
cipal factor  in  the  future  success  of  the  electric  rail- 
way industry,  there  are  other  factors  in  the  demand  for 
its  services  that  play  a  large  part  in  the  welfare  of  a 
community.  The  electric  railway  provides  a  better  la- 
bor market  both  for  employer  and  for  employe.  With 
effective  street  railway  facilities,  the  employe  may  sell 
his  services  to  any  one  of  a  number  of  employers  and, 
on  the  other  hand,  the  employer  has  a  broader  field  in 
which  to  secure  his  help.  A  surplus  of  workers  in  one 
part  of  a  community  can  be  used  to  effect  a  deficit  in 
another  location,  to  the  advantage  of  both  sides— if  the 
transportation  facilities  are  effective. 

Educational  facilities,  the  vital  factor  in  the  sound 
progress  of  our  country,  may,  by  good  transportation, 
be  made  available  to  increasing  numbers  of  our  present 
and  future  citizens.  This  is  one  of  the  most  effective 
means  of  appealing  to  the  better  side  of  the  worker— 
to  give  his  children  the  opportunity  for  a  broader  en- 
deavor. 


October,  1921 


THE  ELECTRIC  JOURNAL 


445 


The  average  worker  is  a  better  producer  for  his 
employer  and  a  better  citizen  for  his  community  if  he 
frequently  has  the  opportunity  to  get  away  and  look  at 
his  work  from  a  different  angle.  Along  with  recrea- 
tion goes  amusement.  No  one  can  deny  the  great  ad- 
vantage of  a  reasonable  amount  of  amusement  to  an\ 
man  and  its  beneficial  effect  on  him  and  his  family. 

All  of  these  advantages  are,  to  a  large  e.xtent,  pos- 
sible only  by  the  use  of  electric  railway  service  and  an 
encouraging  feature  from  our  standpoint  is  that  the 
average  worker  is  willing  to  make  a  reasonable  effort 
to  secure  all  these  advantages  for  himself  and  family, 
but  the  best  thought  is  that  for  the  money  he  spends  in 
supporting  this  necessary  utility,  he  gets  in  return  a 
commensurately  greater  ability  to  earn.  His  enjoy- 
ment of  life  is  limited  only  by  his  effort  and  his  ability. 

Increasing  Future  Prosperity — To  sum  up; — 
There  is  an  urgent  demand  on  the  part  of  emploj'er  and 
employe  in  our  cities  for  better  employes  and  better 
living  conditions.  This  demand  must  be  met  and  it 
will  be  met.  American  communities  can  meet  any 
emergency,  as  is  shown  by  experience. 

The  best  way  in  which  it  can  be  met  is  by  the 
sound  economic  development  of  our  electric  railway 
facilities.  This  will  require  co-operation  between  the 
leaders  of  all  elements,  mutual  understanding  and  fair- 
ness. Those  who  fail  in  leadership  will  be  replaced  by 
real  leaders.  The  inevitable  result  will  be  a  tremend- 
ous increase  in  the  usefulness  of  electric  railway  facili- 
ties, and  the  consequent  and  necessary  prosperity  of 
the  industry. 

This  cannot  mean  that  every  electric  railway  com- 
pany in  the  country  is  going  to  grow  and  prosper. 
Some  are  confronted  by  insurmountable  difficulties. 
However,  the  industry-  generally,  by  furnishing  a  sup- 
ply of  valuable  service  to  meet  a  real  demand  at  a  fair 
price,  is  going  to  prosper.  Its  prosperity  will  be  meas- 
ured by  the  ability  of  its  persoiinel  to  understand  and 
inform  the  minds  of  the  public  and  of  the  car  riders 
regarding  its  service.  In  other  words,  its  ability  to 
produce  and  sell  its  service. 


Illinois  Pioneering  in  Public  Relations 

BERNARD  J.  MULLANEY 

Director, 
Illinois  Committee  on  Public  Utility  Information 

IN  two  years  the  writer  has  attended  six  national 
conventions  of  public  utility  associations — one 
electric,  two  gas,  one  telephone  and  two  electric 
railway  conventions.  All  six  have  had  two  features 
m  common;  the  subject  of  public  relations  in  prac- 
tically every  address,  paper  and  discussion,  except  in 
the  strictly  technical  ones;  and  each  convention  has 
adjourned  and  left  the  subject  of  public  relations  about 
where  it  was  when  the  convention  met.  This  experi- 
ence has  bred  a  conviction  that  the  Illinois  Committee 
on  Public  Utility  Information  has  developed  the  best 
plan  yet  devised   for  bettering  public  relations   in  the 


utility  industry  and  a  hope  that  exploitation  of  this 
Illinois  plan  may  stimulate  still  wider  application  of  it. 
The  "author"  of  the  Illinois  Committee  on  Public 
Utility  Information  is  Samuel  Insull.  Speaking  on 
"Some  Present  Problems  of  the  Public  Utilities,"  be- 
fore the  Illinois  Gas  Association  in  Chicago  on  March 
19,  1919,  Mr.  Insull  drew  attention  to  certain  impres- 
sive statistics  of  the  utility  industry,  and  added : — 

"Think  what  it  will  mean  to  us  (the  public  utilities)  if  we 
can  bring  home,  to  the  communities  in  which  we  operate,  the 
significance  of  the  figures  I  have  just  given  you!  Xow,  it  is  our 
special  job  to  do  just  that;  to  get  at  our  own  employes,  our 
ovyn  stockholders  and  bondholders,  and  our  own  customers. 
We  ought  to  make  it  clear  to  them  that  rate  making,  in  our 
business,  is  not  a  simple  matter  of  fi.xing  a  fiat  price;  that 
proper  systems  of  rates  cannot  be  worked  out  scientifically 
when  politics  enters;  and  that  an  enormous  field  for  develop- 
ment will  be  opened,  alike  to  industry  and  to  ourselves,  by 
proper  systems  of  rates." 

Five  Insull  company  vice  presidents  met  a  little 
later  under  adjuration  to  "get  something  started." 
Representatives  of  both  the  Independent  and  Bell  tele- 
phone interests  also  sat  in.  That  was  the  beginning  of 
the  Illinois  Committee  on  Public  Utility  Information. 
The  Committee  now  has  twenty-seven  members  repre- 
senting all  interests  and  all  phases  of  the  industry  by 
nomination  from  the  state  electric,  gas,  electric  rail- 
way and  telephone  associations,  but  its  program  is 
unchanged.  That  still  is;  "to  conduct  a  systematic 
campaign  for  informing  the  public  on  the  funda- 
mentals, and  particularly  the  economics,  of  the  public 
utility  industry."  The  committee  aims  to  utilize  all 
possible  agencies  legitimately  and  properly  usable  for 
its  purposes. 

When  the  committee  celebrated  its  second  anni- 
versary last  April  it  had  passed  the  5  000  000  mark  in 
pieces  of  literature  distributed.  This  literature,  all 
helpful  to  the  utility  industiy,  was  not  merely  scattered 
broadcast,  but  was  definitely  placed:  with  newspaper 
editors  for  themselves  and  their  readers;  with  cus- 
tomers of  public  utilities ;  with  business  men,  bankers, 
lawyers,  employers  (for  their  employes),  teachers, 
preachers,  librarians,  students  in  colleges  and  high 
schools,  mayors,  members  of  city  councils  and  village 
boards,  public  officials  of  all  kinds  and  candidates  for 
public  office.  Members  of  the  legislature,  for  example, 
received  informative  matter  on  public  utility  questions, 
not  after  they  were  elected,  but  before  they  were  even 
nominated. 

Aside  from  this,  the  committee  has  standardized 
itself  as  an  information  source.  Its  help  is  constantly 
sought  by  newspapers  wanting  data  pertinent  to  cur- 
rent news,  by  students  facing  a  school  debate  or  a 
thesis  task,  by  lectures  wanting  to  freshen  up  platform 
material,  by  writers  of  circular  and  advertising  matter 
for  investment  houses  and  so  on.  Even  members  and 
attaches  of  utility  regulator}'  bodies  draw  upon  the 
committee's  resources. 

A  brief  summary  of  the  routine  work  of  the  com- 
mittee follows: — 

A  news  service  goes  regularly  to  the  900  newspapers  in 
the  state,  about  150  of  them  dailies-  The  matter  carried  in  this 
service  is   informative   rather  than  argumentative,   and  has   to 


440 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.   lo 


be  interesting  enough  to  be  printed  for  its  own  sake. 

Speakers  bulletins  are  issued,  each  devoted  to  some  phase 
of  the  utiHty  industry,  as  for  example;  theory  and  practice 
of  utility  regulation ;  utility  financing ;  utility  rate  making, 
etc.  The  bulletins  furnish  ample  material  to  any  intelligent 
person  for  sound  talks  on  each  subject  and  they  have  been 
widely  used. 

A  bureau  is  operated  to  find  engagements,  before  clubs, 
civic  associations  and  so  on,  for  dependable  speakers  on  utility 
subjects.  In  nearly  lOO  cities,  the  bureau  has  also  organized 
local  utility  managers  to  co-operate  in  promoting  this  public 
discussion. 

Pertinent  addresses  and  articles  by  important  men,  reso- 
lutions or  other  expressions  by  chambers  of  commerce  and 
other  bodies,  exceptional  editorials  and  the  like,  and  special 
matter  for  customers,  investors  and  employes,  have  been 
printed  and  circulated  among  special  classes  by  hundreds  of 
thousands. 

More  than  800  Illinois  high  schools  are  regularly  fur- 
nished informative  literature  for  class  room,  theme  work  and 
debating  society  use.  This  is  of  such  character  that  the  schools 
ask  for  it. 

.\\\  local  managers  of  gas,  electric,  telephone  and  traction 
companies  receive  copies  of  everything  issued  by  the  commit- 
tee. By  letter,  by  discussion  at  association  meetings,  and  by 
reminders  from  higher  executives,  local  managers  are  constantly 
stimulated  to  co-operate  with  one  another  and  with  the  com- 
mittee in  all  possible  ways  of  reaching  the  public ;  and  tlie 
ways  of  co-operating  arc  mapped  for  them  in  considerable  de- 
tail. 

Educating  is  a  slow  process  at  best  and  the  effi- 
cacy of  any  particular  campaign  is  to  be  fairly  judged 
only  by  cumulative  results  over  a  considerable  period. 
But  a  few  outstanding  cicrumstances  may  suggest  what 
the  Illinois  Committee  believes  it  is  accomplishing. 

The  state  press  uses  the  committee's  news  matter 
in  quantity  far  beyond  the  most  optimistic  expectations. 
Evidence  of  absorption  of  utility  facts  by  the  editorial 
mind  is  widespread.  Helpful  editorials  have  appeared, 
literally  by  hundreds,  where  formerly  there  were  none 
or  only  hostile  ones.  Results  in  this  respect  are  so 
obvious  that  committee  members  who  were  sceptics  ii; 
the  beginning  would  not  now  think  of  stopping  the 
work.  It  is  notevk'orth)'  that  the  committee  has  not 
once  been  seriou.sly  accused,  by  newspaper,  politician 
or  utility-baiter,  of  trying  to  "propaganda-ize"  the 
jiublic. 

In  the  summer  of  1920,  certain  politicians  started 
to  make  politics  of  the  necessary  rate  increases  which 
had  been  granted  by  the  public  utilities  commission. 
Abolition  of  state  regulation  and  reversion  to  extreme 
"home  rule"  were  promised  by  one  of  the  political 
factions.  Citizens  and  civic  bodies  then  began  to  take 
notice.  The  Illinois  Chamber  of  Commerce  (a  federa- 
tion of  business  associations  in  the  leading  cities)  con- 
ducted a  referendum ;  and  the  business  sense  of  the 
state,  by  vote,  declared  for  state  regulation  and  against 
"home  rule"  in  the  ratio  of  21  to  i.  The  legislature 
adjourned  in  June  without  abolishing  state  regulation. 
Again,  whenever  there  is  a  utility  association  conven- 
tion in  Illinois,  the  newspapers  print  immeasurably 
more  about  it  than  they  used  to  print  information  on 
the  economics  and  problems  of  the  industry.  None 
of  this  used  to  get  printed  until  our  committee  began 
educating  the  papers  to  recognize  the  utilities  as  a 
source  of  news. 

Many  hold  that  Illinois  is  now  the  best  educated 
state  in  the  union  on  the  utility  industry.     Surely  the 


process  of  educating  it  has  been  of  some  help  to  the 
customer-ownership  campaigns  by  means  of  which  the 
number  of  utility  security  holders  in  the  state  has  been 
increased  from  250000  in  1919  to  nearly  500000  now 
— an  impressive  figure. 

But  the  committee's  work  has  been  by  no  means 
wholly  local  in  effect.  It  has  been  instrumental  in  the 
inauguration  of  similar  work  in  Ohio,  Indiana,  Ken- 
tucky, Nebraska,  Missouri,  Iowa,  Michigan,  Wiscon-  ■ 
sin,  Oklahoma,  Arkansas,  Georgia,  the  New  England 
States,  Colorado,  New  Mexico  and  Wyoming;  and  it 
has  inspired  the  preliminary  steps  in  New  York, 
Kansas,  Texas,  California,  Oregon,  Minnesota, 
Florida,  Tennessee  and  Alabama.  Its  literature  has 
been  at  the  service  of  other  states  and  largely  used. 
Its  publications  have  been  circulated  literally  from 
coast  to  coast. 

Out  of  their  two  and  a  half  years  of  experience, 
members  of  the  Illinois  Committee  have  come  to  cer- 
tain definite  conclusions.  One  is  that  really  effective 
cultivation  of  public  good  will  is  a  task  for  composite 
intelligence  of  the  highest  order;  a  task  for  technical 
skill  and  experience  in  this  special  field,  plus  the  active 
assistance  of  the  industry's  ablest  men. 

Another  conclusion  is  that  effort  to  cultivate 
I'ublic  good  will  for  any  particular  branch  of  the 
utility  industry — gas,  electricity,  telephone  or  traction 
— gains  in  effectiveness  when  it  is  part  of  a  campaign 
for  the  whole  industry,  as  under  the  Illinois  plan.  The 
appeal  is  for  a  great  and  all  prevading  industry  in- 
stead of  for  a  special  interest.  At  the  same  time,  a 
special  appeal  for  gas  or  electricity  or  telephones  or 
traction  is  in  nowise  weakened,  but  gains  from  the 
background  and  support  furnished  by  the  broader, 
general  appeal. 

Still  another  conclusion  is  that  nationalized  efforts 
in  this  field  are  ineffective  when  direction  of  them  from 
one  central  point  is  attempted.  Managers  of  the  "war 
drives"  all  found  that  they  could  not  get  results  that 
way.  They  had  to  organize  regionally,  by  states,  and 
by  communities,  and  national  control  or  supervision 
was  only  for  co-ordinating  and  focusing  the  regional 
efforts. 

The  logic  of  these  conclusions  will  be  recognized 
some  day  by  men  at  the  head  of  the  utility  industr)'. 
They  will  then  insist  that  the  Illinois  plan  be  put  into 
operation  in  all  states  of  the  union,  for  the  co-operative 
good  of  the  entire  utility  industry,  and  .with  just 
enough  national  supervision  to  stimulate  and  encourage 
the  weaker  states  and  to  co-ordinate  and  focus  the 
work  in  all  states.  When  that  is  done,  you  will  have 
the  machinery  for  getting  action  nationally  upon  any 
matter  in  which  the  utilities,  or  any  group  of  them, 
may  be  interested.  It  may  be  a  traction  matter  today, 
a  gas  matter  tomorrow,  an  electric  light  and  power 
tnatter  the  next  day,  a  taxation  matter  the  day  follow- 
ing. No  matter;  the  machiner}'  will  be  equally  effica- 
cious for  all.     When  that  time  comes,  the  Illinois  com- 


October,  1921 


THE  ELECTRIC  JOURNAL 


447 


mittee  will  cheerfully  contribute,  for  the  common 
good,  all  that  it  has  learned  while  doing  the  things 
which  have  been  briefly  sketched  here. 


The  Standard  Types  of  City  Cars 

The  Country  Really  Needs  to  Meet 
Traffic  Requirements 

VV.  H.  HEULINGS,  Jr. 

Vice  President  and  Gen.  Mgr.  Sales, 
The  J.  G.  Brill  Company 

THE  ECONOMIC  value  of  standardization  in  the 
production  and  maintenance  of  electric  railway 
rolling  stock  is  largely  responsible  for  the  pres- 
ent tendency  toward  the  general  use  of  certain  stand- 
ard types  of  city  cars  which  have  been  developed  and 
already  extensively  adopted.  It  might  be  said  that  this 
tendency  toward  standardization  of  car  design  is  the 
result  of  changed  conditions  in  the  industry  which 
make  it  imperative  that  advantage  be  taken  of  every 
opportunity  to  offset  the  high  cost  of  operation  and 
the  competition  developed  within  recent  years  by  pri- 
vately owned  automobiles  and  irresponsible  jitneys. 

When  in  183 1  John  Stephenson,  the  "daddy  of  the 
street  railway  car"  created  the  first  horse-drawn 
vehicle  to  be  operated  on  rails  he  took  as  his  model  the 
then  most  popular  type  of  vehicle  for  public  transpor- 
tation— the  stage  coach.  This  was  the  beginning  of 
street  railway  car  design  and  little  was  realized  at  that 
time  of  the  development  that  was  destined  to  follow.  In 
those  days  the  lack  of  a  quick  and  convenient  means 
of  "annihilating"  distances  had  retarded  the  growth  of 
communities  and  "mass  transportation"  was  a  term 
unknown  to  the  men  who  were  the  pioneers  in  tl.'e 
street  railway  industry. 

In  this  respect,  the  coming  of  electricity  as  motive 
power  in  1888  was  a  most  important  event.  At  first 
the  cars  were  small,  conforming  in  design  to  the  lines 
of  the  one  and  two-horse  cars  which  were  then  in 
vogue.  But  the  improvement  which  electricity  brought 
about  over  the  "hay-burners",  as  the  horse  cars  had 
become  known,  so  popularized  street  railway  service 
that  larger  cars  mounted  on  two  four-wheel  trucks  in- 
stead of  one  were  designed,  and  thus  the  foundation 
was  laid  for  many  of  the  designs  which  are  known  to 
the  industry  today.  In  some  communities,  of  course, 
where  conditions  prevented  an  increase  in  travel,  the 
smaller  cars  were  sufficient  to  meet  requirements. 

Many  improvements  were  brought  forth.  Open 
cars,  which  had  become  popular  in  warm  weather, 
were  in  many  cases  superseded  by  cars  with  the  semi- 
convertible  window  system  making  possible  the  use  of 
the  same  car  equipment  in  all-year  service,  and  also 
eliminating  to  a  large  extent  boarding  and  alighting 
accidents.  There  was  also  introduced  the  prepayment 
method  of  fare  collection  with  the  adoption  of  the 
closed  platforms  and  mechanically-operated  doors  and 
steps.  All  these  innovations  were  introduced  in  the 
interests  of  efficiency;  car  design  keeping  pace  with  the 


progress  of  the  industry  and  travel  increasing  without 
restraint.  But  eventually  the  rapidly  increasing  num- 
ber of  privately-owned  automobiles  and  the  entrance 
into  competition  of  the  gasoline  motorbus  and  the  jit- 
neys cut  deeply  into  the  street  railway's  business.  The 
loss  was  more  apparent  between  the  peak  periods  of 
the  day,  when  it  was  almost  impossible  to  even  pay  the 
cost  of  operation,  which  had  so  advanced  by  the  in- 
creased cost  of  materials  and  labor  due  to  the  war. 

The  public  did  not  prefer  to  ride  on  the  jitneys 
but  "more  frequent  service"  which  the  electric  rail- 
ways could  not  furnish  with  their  large  heavy  equip- 
ment decided  against  the  latter.  As  a  solution  of  the 
problem  it  was  recognized  that  a  light-weight  car  was 
necessary  to  reduce  power  costs  and  that  to  provide 
more  frequent  service  a  larger  number  of  car  units  was 
necessar)'.  The  standard  safety  car  was  designed  in 
order  to  eiifect  economies  in  power  consumption  and 
track  maintenance,  which  would  permit  the  operation 
of  a  larger  number  of  cars  at  less  expense  and  by  the 
shorter  car  intervals  give  more  frequent  service  to  the 
public.  Its  lightweight,  therefore,  of  only  16000  lbs. 
complete  is  responsible  largely  for  the  operating  re- 
sults obtained.  Some  contend  that  the  use  of  double 
doors  to  shorten  the  time  of  passenger  interchange  by 
the  simultaneous  ingress  and  egress  of  passengers  is 
necessary  on  heavy  traffic  lines.  The  experience  of 
many  operators  has  been  that  the  quicker  starting  and 
stopping  of  the  safety  car  offsets  the  difference  in 
passenger  interchange  and  that  in  addition  the  single 
door  of  the  standard  car  is  essential  to  one-man  opera 
tion  in  that  the  operator  is  required  to  keep  his  eyes 
on  but  one  line  of  passengers  at  a  time  and  there  is  less 
possibility  of  his  missing  fares.  Also  the  increase  in 
weight  by  the  use  of  double  doors  reduces  the  operat- 
ing economies.  The  standard  or  "Birney"  safety  car 
is  undoubtedly  the  best  type  for  all-day  service  on  any 
line  in  any  city  where  car  intervals  can  be  shortened 
and  an  increase-  in  the  number  of  passengers  carried 
can  be  obtained. 

Where  large  cars  have  been  operated  on  as  short 
headways  as  practicable,  either  in  all-day  service  or 
during  peak  periods  only,  the  Peter  Witt  car  is  best 
suited  to  meet  traffic  requirements  because  of  its  ca- 
pacity, and  ideal  arrangement  for  the  quick  handling 
of  passengers.  Under  these  conditions  passenger  in- 
terchange is  most  important  and  this  type  of  car  with 
its  "pay-as-you-pass"  method  of  fare  collection  accom- 
plishes this  in  quicker  time  than  any  design  of  car  yet 
developed.  Passengers  enter  by  way  of  the  front  plat- 
form in  two  columns  and  as  the  conductor  is  stationed 
on  the  forward  side  of  the  center  doors  the  entire  front 
half  of  the  car  sen-es  as  a  long  loading  platform.  A. 
most  practical  seating  arrangement  is  used,  with  trans- 
N  erse  seats  in  the  rear  end  of  the  body  and  longitudinal 
in  the  front  end.  This  influences  passengers  to  pro- 
ceed to  the  rear  end  of  the  car,  paying  their  fares  as 
they  pass   the   conductor,   and  a   better  distribution  of 


448 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


the  passenger  load  results.  There  is  no  delay  in  load- 
ing passengers,  neither  is  there  any  at  unloading  points, 
it  being  necessary  for  the  conductor  only  to  collect 
fares  from  those  who  remained  in  the  forward  end  of 
the  car.  The  wide  center-exit  doors  also  permit 
passengers  to  leave  in  two  columns. 

It  is,  therefore,  a  fact  that  any  street  railway  com- 
pany, no  matter  what  volume  of  business  it  does,  can 
standardize  its  rolling  stock  on  Bimey  safety  cars  and 
Peter  Witt  cars,  using  the  little  cars  for  a  given  serv- 
ice and  the  larger  Peter  Witt  cars  only  where  the  vol- 
ume of  travel  requires  large-capacity  cars  on  the 
shortest  possible  headway. 


Wasting  Capital  in  Bus  Competition 

EDWIN  D.  DREYTUS 

Engineer, 
Pittsburgh,   Pa. 

ANALOGIES  between  nature  and  business  are 
usually  most  striking.  Thus,  water  passing  over 
a  dam  without  being  utilized  can  never  be  re- 
claimed for  that  purpose  and  correspondingly  it  is  true 
in  many  respects  in  the  case  of  our  capital  resources 
employed  in  ungainful  business  pursuits.  Our  financial 
and  credit  agencies  report  the  commercial  failures 
which  of  course  fluctuate  with  business  conditions.  The 
primary  causes  of  failure  for  a  pre-war  year  were  clas- 
sified by  the  leading  authorities  on  the  subject  as  fol- 
lows:— Incompetence  and  inexperience  15.3  percenr, 
lack  of  capital  31.6  percent,  unwise  credits  and  failure 
of  others  19.9  percent,  extravagance  and  neglect  i.(3 
percent,  competition  and  specific  conditions  21  percent, 
speculation  and  fraud  10.6  percent. 

Lack  of  knowledge  of  the  demand  for  the  product, 
commodity  or  service  and  the  complete  cost  of  fur- 
nishing it  are  too  little  understood,  and  this  practically 
embraces  all  of  these  causes,  except  the  last  two,  of 
which  specific  conditions  covering  sudden  price  changes 
and  other  unforseen  developments  is  predominant. 
Fortunately  in  most  businesses,  the  margin  of  safety 
is  sufficient  to  permit  a  relatively  wide  range  of  error 
without  precipitating  disaster.  In  other  words,  the  de- 
gree of  profit  in  commercial  and  manufacturing  lines 
must  vary  widely.  With  public  utilities  the  case  is 
quite  different.  It  has  a  turn-over  of  its  investment 
only  once  in  three  to  seven  years  as  compared  with 
commercial  and  manufacturing  activities  whose  turn- 
over of  capital  commonly  takes  place  several  times  dur- 
ing the  year. 

A  menacing  development  to  the  electric  railway 
during  recent  years  has  been  the  auto  bus.  In  most 
states,  this  method  of  transportation  is  of  a  parasitic 
growth,  attacking  'companies  in  the  most  productive 
business  areas  only.  As  a  general  substitute  for  the 
trolley  car,  the  auto  bus  is  impracticable  in  its  present 
stage  of  development.  There  are  conditions  where  it 
can  be  used  as  an  auxiliary  to  the  electric  trolley,  but 
at     present,     where      regulation      does     not     obtain. 


it  is  more  prevalent  in  the  form  of  competition. 
With  the  heavy  investments  required  in  the  railway 
field,  a  substantial  traffic  must  be  maintained  in  order 
that  the  business  may  succeed.  Auto  busses  needless'y 
duplicate  the  well-established  trolley  service  and  there- 
by create  ruinous  competition.  It  is  evidently  unwise 
for  the  travelling  public  to  encourage  such  economical- 
ly unsound  competition  because,  eventually,  they 
must  bear  the  inevitable  burden  by  paying  higher  fares 
or  else  obliging  themselves  to  be  content  with  dimin- 
ished service  and  accommodations.  The  average  auto 
bus  total  operating  cost  is  from  20  to  50  percent 
more  per  "seat  mile"  than  that  of  the  electric  trolley. 
Moreover,  the  convenience,  accommodations  and  regu- 
larity of  service  are  distinctly  in  favor  of  the  well  es- 
tablished trolley  service.  The  Des  Moines  case  need 
only  be  alluded  to  in  this  connection.  Undoubtedly 
their  bus  experience  has  been  costly  to  this  municipali- 
ty, directly  by  slowing  down  business  and  indirectly 
in  the  loss  of  commercial  prestige. 

The  psycholog}'  of  the  masses  in  resenting  rate 
and  fare  advances  during  the  time  of  rising  costs  is 
one  factor  which  has  contributed  to  the  temporary  ac- 
tivities of  the  auto  bus.  Another  factor  has  been  the 
lack  of  employment,  which  has  driven  many  of  the  la- 
boring class  who  accumulated  a  surplus  when  wages 
were  high  to  attempt  to  earn  a  livelihood  in  the  trans- 
portation business.  In  the  case  of  some  of  the  more 
prominent  and  conspicuous  bus  lines  they  have  been 
fostered  by  that  class  of  men  who  may  be  properly 
designated  as  "financial  raiders,"  who  usually  promote 
such  schemes  and  finally  unload  their  stock  on  the  un- 
suspecting public.  In  any  case,  the  capital  so  applied 
is  evidently  unwisely  employed,  and  it  thus  becomes  a 
loss  that  the  people  as  a  whole  must  bear  since  the  cap- 
ital involved  might  have  been  devoted  to  more  produc- 
tive undertakings. 

A  few  exceptions,  like  the  Fifth  Avenue  bus  line 
in  New  York  City,  may  be  cited  as  examples  of  where 
auto  busses  pay,  since  a  ten  cent  fare  obtains  with  them, 
whereas  the  electric  railways  in  New  York  are  re- 
stricted to  a  five  cent  fare.  But  it  is  also  true  that  an 
electric  trolley  system  would  have  been  even  more  pro- 
fitable in  that  location  and,  reduced  to  the  last  analysis, 
the  auto  bus  exists  in  such  places  for  the  reason  that 
it  least  detracts  from  and  interferes  with  the  purpos-eg 
and  esthetic  surroundings  on  particular  thoroughfares. 

This  whole  question  is  at  once  very  important  and 
particularly  serious  in  numerous  instances.  The  in- 
jury to  a  few  will  often  react  unfavorably  upon  the  ma- 
jority. Collective  wealth  is  increased  through  produc- 
tive efforts  only — not  through  destructive  influences. 
Can  the  people  of  the  country  afford  to  trifle  with  such' 
wasteful  practices  which  will  inevitably  become  in- 
strumental in  diminishing  and  restricting  individual 
opportunities  for  a  greater  development  of  those  fa- 
cilities that  contribute  to  their  material  comfort  and 
convenience?     This    is    inconceivable    and    our   efforts 


October,   1921 


THE  ELECTRIC  JOURNAL 


449 


should  be  redoubled  to  bring  additional  light  to  benr 
upon  this  subject  in  order  that  a  sane  and  practical 
transportation  policy  shall  obtain  in  all  localities,  either 
through  effective  municipal  or  state  regulation. 


Encourage  Young  Engineers  to  Enter 
Rail'way  Organizations. 

H.  H.  JOHNSON 

Organization  Engineer, 
Chicago  Elevated  Railways  Co. 

THE  electric  railway  industry  is  still  passing 
through  the  most  critical  period  in  its  history. 
The  war  period  with  its  rising  costs  of  opera- 
tion, struggles  for  increased  fares  and  inability  to  ob- 
tain competent  help  may  have  passed,  but  there  is  much 
hard  work  to  be  done  to  restore  the  industry  to  a  nor- 
mal basis  and  build  up  its  financial  credit.  There  has 
been  a  tendency  on  the  part  of  some  employees  and  op- 
erators to  become  discouraged  in  the  future  of  the  in- 
dustry and  to  sever  their  relation  with  it,  even  after 
spending  the  greater  part  of  their  life  in  it.  It  has 
also  been  ditificult  to  attract  the  right  kind  of  pro- 
gressive young  men  to  enter  the  electric  railway  field 
as  their  life  work.  They  can  scarcely  be  blamed 
for  their  hesitancy  under  the  conditions  which  have 
existed  during  the  past  few  years.  However,  the  elec- 
tric railway  has  become  a  part  of,  and  is  indispensable 
to  our  national  life  and  civilization.  There  have  been 
individual  companies  and  isolated  properties  which 
discontinued  operation  and  there  will  probably  be 
others  in  the  future,  but  the  electric  railways  as  a  whole 
and  as  an  industry  are  necessary  to  the  growth  and  de- 
velopment of  the  nation. 

In  order  to  hasten  the  recuperation  of  the  credit 
and  standing  of  the  electric  railways,  it  is  necessary 
that  everybody  connected  with  the  industry  from  presi- 
dent to  platform  man  and  car  repairer  put  forth  his 
utmost  effort  to  win  the  confidence  and  respect  of  the 
communities  in  which  his  company  operates.  The 
service  rendered  the  public  must  be  made  the  mont 
economical  and  efficient  that  can  be  provided.  Oper- 
ating companies  must  be  found  to  be  above  reproach 
when  investigated  by  the  various  commissions  and 
regulatory  bodies.  To  bring  about  this  condition 
broad  gauged  men  are  required  for  operation  of  the 
electric  railway  properties.  There  is  a  greater  need 
for  these  men  at  the  present  time  than  ever  before. 

This  is  especially  an  opportune  time  for  the  engi- 
neer in  electric  railway  service.  The  conditions  just 
described  have  clearly  demonstrated  to  the  manage- 
ments the  value  of  the  trained  engineer.  It  is  abso- 
lutely necessary  that  every  detail  and  every  method  of 
operation  be  analyzed  and  studied  carefully.  The 
trained  engineer  has  proven  to  be  the  man  best 
equipped  to  make  these  studies  and  analyses.  Ac- 
cordingly his  services  are  more  highly  valued  by  the 
electric  railways  today  than  at  any  previous  time. 


The  industrial  and  manufacturing  companies  have 
also  recognized  the  value  of  the  engineer  and  in  many 
cases  have  attracted  j'oung  engineers  from  the  electric 
railway  held.  The  managements  of  electric  railways 
must  see  that  conditions  are  made  which  will  attract 
young  engineers  into  their  service.  After  entering  the 
service  they  must  be  trained  and  developed  in  such  a 
manner  as  to  maintain  their  interest.  This  result  will 
not  be  accomplished  by  hiring  a  young  engineer, 
putting  him  in  some  job  and  then  forgetting  about  him. 
Some  official  of  the  railway  company  must  be 
designated  to  look  after  the  young  engineers  and  be 
held  responsible  for  their  education. 

Many  young  men  on  leaving  an  engineering  school, 
consider  their  education  completed.  This  is  far  from 
true,  as  they  have  received  general  instruction  in  a 
variety  of  subjects  but  have  not  learned  any  business 
thoroughly.  Their  minds  have  been  developed  and 
trained  to  study  and  analyze  problerhs  as  they  are  pre- 
sented, but  they  have  had  practically  no  training  in  the 
operation  of  a  railroad.  The  management  must 
recognize  these  facts  and  must  give  their  young  men 
the  necessary  training  to  make  raih-oad  men  out  of 
them.  They  should  be  given  an  opportunity  to  work 
in  the  different  departments  of  the  road,  to  get  a  gen- 
eral idea  of  the  business.  During  the  period  of  work- 
ing through  the  various  departments  each  young  man 
will  have  the  opportunity  of  determining  the  branch 
of  the  industry  in  which  he  is  most  interested  and  the 
management  will  have  the  chance  to  decide  whether 
the  young  man  is  fitted  for  railway  work.  If  he  is, 
he  will  doubtless  show  an  inclination  for  a  certain 
branch  of  the  work  and  should  naturally  be  drawn  into 
one  of  the  departments  into  vvhich  an  operating  com- 
pany is  divided.  If  he  is  eventually  assigned  to  the 
mechanical  or  maintenance  of  way  department,  he  will 
be  more  valuable  if  he  has  also  the  transportation  de- 
partment's viewpoint.  On  the  other  hand,  if  he  enters 
the  transportation  department,  his  experience  in  main- 
taining cars,  track  and  roadbed  and  in  the  operation  of 
power  houses  and  substations  will  make  him  a  more 
efficient  transportation  man. 

Much  of  the  friction  which  exists  between  the 
different  departments  would  be  eliminated  if  depart- 
ment heads  looked  at  the  problem  from  all  sides,  in- 
stead of  having  in  mind  the  greatest  benefit  to  their 
own  department.  It  must  be  remembered  that  the 
road  is  being  run  to  carry  passengers  and  serve  the 
public  economically  and  efficiently,  not  for  the  benefit 
or  record  of  any  one  department. 

During  this  period  of  training  and  education  the 
young  engineer  must  work  as  one  of  the  men.  He 
should  work  as  a  trainman ;  as  a  helper  or  repairman 
in  the  shops;  as  a  laborer  or  trackman  on  the  tracks, 
etc.  He  should  work  under  the  same  conditions  as 
the  regular  workman  and  in  fact  he  must  be  one  of 
the  workmen.  He  must  get  their  ideas,  become  familiar 
with  their  thoughts,  with  their  manner  of  living,  with 


45° 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


their  desires,  with  their  ideas  of  what  the  future  holds 
in  store  for  them,  with  the  effect  upon  them  of  the  issu- 
ing of  various  instructions  and  orders.  He  must  study 
humanity.  He  must  be  able  to  see  the  workingman's 
side  of  the  case.  If,  at  a  later  date,  he  should  become 
a  supervisor  or  foreman,  he  will  find  that  the  handling 
of  men,  without  friction,  is  a  greater  problem  and  re- 
quires closer  study  and  thought  than  acquiring  the  en- 
gineering knowledge  necessary  to  his  position. 

Manufacturing  companies  seem  to  have  had  a  bet- 
ter appreciation  of  the  value  of  developing  young  en- 
gineers than  the  railways.  They  have  solicited  their 
services  and  established  rates  of  pay  which,  with  the 
educational  features,  attracted  the  young  engineers 
into  their  plants.  Instead  of  sitting  back  and  making 
the  young  engineers  force  their  way  into  the  service, 
the  electric. railways  must  seek  out  capable  young  en- 
gineers and  encourage  them  to  enter  their  service.  The 
rates  of  pay  must  be  commensurate  with  the  salaries 
paid  in  other  industries.  The  instruction  and 
education  of  these  young  men  must  be  placed  in 
the  hands  of  a  competent  official  of  the  company  who 
will  take  an  interest  in  them  and  act  in  the  nature  of  a 
personnel  officer. 

In  addition,  the  electric  railways  must  adopt  a  gen- 
eral plan  of  training  employes  in  all  departments  for 
better  positions  and  a  general  plan  of  promotion.  The 
foreman  should  be  training  some  helper  to  take  a  me- 
chanic's position.  If  one  of  the  mechanics  should  quit 
the  helper  sho-.;!d  be  promoted  and  a  new  emplo\e 
started  in  at  the  bottom.  The  general  foreman  should 
be  training  some  sub-foreman  for  the  position  of  x 
foreman.  The  master  mechanic  should  know  and  be 
gradually  training  the  forman  who  will  be  promoted 
in  case  tlie  general  foreman  should  become  incapaci- 
tated. There  are  various  opportimities  such  as  vaca- 
tion time  and  absence  due  to  sickness,  when  the  chosen 
sub- foreman  may  have  a  chance  to  act  as  foreman  and 
gradually  obtain  the  experience  of  the  higher  position. 

The  j-oung  engineer  just  entering  upon  his  life's 
work  is  especially  interested  in  the  opportunities  foi 
advancernent.  As  a  rule,  he  is  willing  to  do  hard  work 
and  go  through  the  apprenticeship  training  if  he  can 
see  a  fair  chance  for  advancement  later  on.  The  plan 
of  training  and  a  general  plan  of  promotion,  as  here 
briefly  described,  will  show  the  young  man  that  the  op- 
portunity for  advancement  is  always  present.  Some 
one  in  the  organization  will  be  promoted  when  there  is 
a  vacancy.  Whether  he  will  be  the  favored  one  will 
depend  upon  his  past  record  and  whether  he  is  pre- 
pared for  the  position  which  is  open.  Every  emplove 
will  have  something  to  look  forward  to.  Steady  and, 
dependable  men  will  seek  to  enter  an  organization  of 
this  kind.  Young  men,  both  with  and  without  en- 
gineering training,  will  be  attracted  to  it.  The  officials 
will  have  worked  up  through  the  ranks  after  proving 
their  ability  through  years  of  service.  It  will  not  be 
necessary  to  experiment  with  outsiders  in  supervisory 


positions.     The  organization  will  be  well  balanced  and 
fully  equipped  for  any  emergency. 


The  Electric  Railway  and  the  Jitney 

F.  G.  BUFFE 

Gciu'ial  Manager,   for  the  Receivers, 
The  Kansas  City  Kailway  Company 

PRIOR  to  July,  1914,  one  might  have  searched 
in  vain  through  the  index  of  technical  magazines 
for  the  word  "jitney."  No  such  slang  expression 
had  ever  been  allowed  to  creep  into  the  dignified 
columns  of  these  journals.  From  that  time  on,  how- 
ever, the  term  jitney  takes  up  perhaps  as  much  space 
as  any  other  expression.  The  lowly  jitney  has  taken 
the  time  and  attention  of  street  railway  officials  and 
directors;  has  intruded  into  the  discussions  of  finan- 
ciers; has  invaded  the  courts,  local  and  supreme;  has 
occupied  the  time  of  city  councillors  and  public  service 
commissioners;  and  has  intruded  into  !egislati\  • 
halls.  The  jitney  has  been  and  is  today  a  very  trouble 
some  customer  and  has  been  the  cause  of  more  than 
one  street  railway  receivership.  It  is  a  pest,  a  pirate, 
an  illegal  competitor,  and  many  other  things  expressed 
publicly,  whereas  the  things  said  about  it  in  private 
would  not  do  to  print.  Regardless  of  this,  however, 
the  fact  remains  that  in  many  cities  jitneys  are  daily 
hauling  hundreds  of  thousands  of  people  and  depriving 
street  railways  of  the  revenue  necessary  for  their 
actual  operation.  In  spite  of  what  street  railway 
people  say  of  the  jitney,  it  is  welcomed  with  open  arms 
by  too  many  of  our  fellow  citizens  for  our  own  com- 
fort and  wellbeing. 

July  I,  1914,  the  first  rattley  tin  !Lizzie  appeared 
on  the  streets  of  Los  Angeles,  bearing  the  sign,  "5 
cents."  Little  did  the  jehu  of  this  contraption  know 
the  furor  he  was  to  cause  in  transportation  circles,  and 
doubtless  this  knowledge  would  have  made  little  dif- 
ference. He  was  out  of  a  job  and  was  the  possessor 
c'  a  second  hand  automobile.  The  pavements  of  Los 
Angeles  were  good,  the  weather  salubrious,  and  people 
were  riding  to  and  fro  paying  five  cents  for  the  privi- 
lege. He  combined  these  factors  and  carried  on  the  first 
few  trips  enough  passengers  to  buy  a  scjuare  meal,  and 
the  avalanche  was  loosened.  The  newspapers  heralded 
his  success  and  that  of  his  fellows  in  Los  Angele? 
throughout  the  country,  and  in  large  cities  everywhere 
the  combination  of  a  jobless  man  and  an  old  car  began 
to  cause  trouble  for  the  street  railwn>  people.  As 
George  Fitch  once  said,  "There  was  no  other  way 
quite  as  successfully  to  junk  a  second  hand  auto- 
mobile." 

At  first  the  jitney  was  a  fly-by-night  affair,  but 
soon  the  drivers  saw  the  advantages  of  organization 
and  iitney  associations  sprang  up  over  night.  These 
voluntaiy  associations  laid  out  routes  and  schedules, 
and  began  to  form  the  nucleus  of  a  skeleton  transpor- 
tation system  so  that  what  was  at  first  a  mere  annoy- 
ance  assumed    the   proportions   of    a    serious   menace. 


October,  1921 


THE  ELECTRIC  JOURNAL 


431 


The  jitney  business  had  a  rapid  beginning,  and  ahnost 
as  rapid  an  ending  at  the  outset.  This  ending  came 
about  just  as  soon  as  the  drivei  of  a  second  hand 
automobile  reaHzed  that  depreciation  was  actual  as 
well  as  theoretical.  He  discovered  that,  with  his  car 
out  of  business,  his  receipts  had  gone  to  pay  operating 
and  personal  expenses  and  there  was  no  money  in  the 
bank  with  which  to  continue  operations  with  a  new  car. 
So  the  year  1915  began  to  see  their  disappearance,  and 
soon,  outside  of  a  few  favored  localities,  the  jitney 
had  practically  ceased  to  worry  street  railway  opera- 
tors. The  business  depression  which  was  generally  re- 
sponsible for  them  had  passed  away,  the  war  in  Europe 
was  returning  prosperity  to  our  factories,  and  jobless 
men  were  daily  becoming  scarcer.  With  wages  mount- 
ing there  was  no  attraction  in  leaving  an  eight  hour 
job  for  an  eighteen  hour  one  driving  a  jitney  at  a  five 
cent  fare. 

As  the  old  saying  has  it,  however,  "it  is  an  ill 
wind  that  blows  no  one  some  good,"  and  out  of  the 
first  jitney  competition  came  some  decided  benefits. 
Street  railway  operators  sensed  the  possibility  of  direct 
competition ;  some  had  suffered  from  it,  and  everyone 
was  beginning  to  devise  ways  and  means  to  meet  it. 
The  safety  car,  which  has  been  such  a  boon  to  the  in- 
dustry, was  one  direct  result  of  the  jitney.  In  many 
localities  and  in  some  states,  the  early  jitney  competi- 
tion had  brought  about  restraining  ordinances  and 
laws. 

Late  in  1917  and  early  in  iqiS  new  factors  and 
conditions  restored  the  defunct  jitney  competition  to 
life,  and  this  recurrence  is  more  serious  than  before. 
While  the  plague  is  soinewhat  abated  in  certain  locali- 
ties, in  many  others  it  is  playing  havoc  with  transpor- 
tation conditions.  With  mounting  material  and  labor 
costs,  the  five  cent  fare  in  1917  began  to  be  a  thing  of 
the  past.  The  street  railway  companies  throughout 
the  United  States  were  rushing  to  regulatory  bodies 
for  fare  increases  and  securing  them.  These  fare  in- 
creases opened  up  the  opportunity  for  jitney  competi- 
tion. They  worked  in  favor  of  the  jitney  in  two  di- 
rections. In  the  first  place  the  public  in  practically 
every  community  resented  the  change  from  five  cents 
to  a  higher  fare.  This  feeling  was  increased  by  un- 
favorable newspapers.  In  many  places  the  public 
walked  to  show  its  disfavor,  and  as  they  became  avail- 
able rushed  to  the  jitney.  The  increased  street  railway 
fares  made  it  possible  for  the  jitneys  to  double  their 
former  fare  of  five  cents  and,  coming  at  the  psycho- 
logical moment,  the  public  cheerfully  came  to  their 
support.  Economically  the  jitney  was  better  off  under 
a  ten  cent  fare  than  under  a  five  cent,  and  in  many 
localities  jitney  drivers  were  able  to  meet  their  ex- 
penses and  accumulate  some  money. 

Strongly  intrenched  jitney  associations  sprang  up 
in  a  number  of  cities,  notably  Kansas  City,  Indian- 
apolis, Newark,  Bridgeport,  and  others.  War  condi- 
tions and  war  industries  made  possible  the  strengthen- 


ing of  this  structure.  In  many  cities  street  railways 
had  all  they  could  do  with  the  facilities  at  hand,  to 
handle  the  business,  and  the  jitneys  were  taking  the 
overflow. 

A  new  element  was  injected  into  this  competition, 
namely,  the  motorbus.  Operated  on  permanent  routes, 
with  regular  headways,  offering  a  fairly  rapid  and  com- 
fortable ride,  these  vehicles  soon  established  them- 
selves in  public  favor.  In  many  cities  they  were 
heralded  as  the  forerunners  of  a  system  that  would 
supplant  the  existing  street  railways.  Enterprising 
gentlemen  entered  the  bus  business  and  from  several 
places  propaganda  was  sent  to  chambers  of  commerce, 
city  councils,  etc.  from  those  who  for  a  fee  offered  to 
put  bus  transportation  in  any  city.  The  automobile  in- 
dustry saw  a  new  and  highly  lucrative  field  opening, 
and  new  bus  models  began  to  appear  not  only  in  adver- 
tisements but  upon  the  streets.  The  situation  soon  be- 
came and  is  today  extremely  serious  in  many  localities. 

However,  like  the  rise  and  fall  of  the  first  jitney 
epidemic,  indications  are  that  this  recurrence  is  on  the 
downward  part  of  the  curve,  and  that  it  too  will  pass 
away.  An  educated  public  opinion  and  several  very 
expensive  examples,  expensive  both  for  the  companies 
involved  and  for  the  communities,  have  helped  in  this 
developement.  Those  visionaries  who  a  few  months 
ago  were  hailing  the  advent  of  the  bus  as  the  death 
knell  of  electric  traction  are  becoming  fewer  since 
Bridgeport,  Toledo,  and  Des  Moines  have  furnished 
sign  posts  so  those  who  run  may  read. 

There  has  not  yet  been  offered  any  argument  that 
can  eft'ectually  prove  that,  for  mass  transportation  in 
our  large  centers,  anything  will  in  the  next  fifty  years 
supplant  the  modern  electric  street  railway.  Further- 
more, it  is  rapidly  becoming  recognized  by  the  public 
generally  that  adequate,  reliable,  efficient  street  railway 
service  cannot  be  furnished  if  competition  is  to  be  per- 
mitted; that  no  community  can  support  two  independ- 
ent systems  of  transportation,  the  one  upon  which  the 
public  relies  being  burdened  by  charges  such  as  paving, 
?nd  so  on.  The  public  is  also  realizing  that  adequate 
street  railway  transportation  means  an  investment  in 
facilities  sufficient  to  cover  the  entire  city  and  to  trans- 
port its  population  at  any  and  all  times.  It  realizes 
that  this  investment  cannot  be  maintained  and  con- 
tinued if  unrestrained  cotnpetition  is  to  be  permitted  to 
take  the  revenues  necessary  to  maintain  and  continue 
this  investment.  The  public  is  also  recognizing  the 
fact  that  to  provide  a  de  luxe  automobile  service  for  a 
comparatively  small  number,  the  large  majority  who 
depend  upon  the  street  railways  are  being  penalized  by 
higher  fares  and  inadequate  service.  The  public 
furthermore  recognizes  that,  if  the  entire  town  is  to  be 
served  the  outlying  districts  and  the  long  hauls,  then 
competition  must  not  be  permitted  to  cover  the  heart  of 
the  traffic  possibilities  with  short  hauls,  taking  the 
cream  of  the  business  from  the  company  upon  whom 
falls  the  legal  obligation  to  render  a  complete  transpor- 
tation service. 


452 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


There  never  has,  of  course,  been  competition  in  the 
strict  sense  of  the  word,  because  competition  impHes  "a 
fair  field  and  no  favors,"  and  this  cannot  be  said  as  be- 
tween the  jitneys  and  street  railway  service.  The  jit- 
ney is  unrestrained,  heart-whole  and  fancy  free.  It 
can  select  the  street  it  desires;  can  furnish  service  only 
to  thickly  settled  districts;  is  under  no  obligations  to 
serve  any  particular  section;  is  not  called  upon  to  pay 
for  the  pavement  it  destroys  nor  is  it  subject  to  any 
of  the  other  charges  and  obligations  imposed  upon  the 
street  railways. 

Education,  and  following  education,  proper  regu- 
latory laws  and  ordinances,  are  the  weapons  which  are 
putting  the  jitney  and  unrestrained  bus  competition 
out  of  the  picture,  and  will  continue  to  do  so.  The 
people  are  waking  up  to  the  dangers  involved ;  property 
owners  see  the  hand-writing  on  the  wall  if  street  rail- 
way systems  are  allowed  to  be  permanently  injured, 
and  as  a  result  city  councils  everywhere  are  solving  the 
problem  by  ruling  out  the  jitney. 

In  Kansas  City  very  recently  two  ordinances  have 
been  passed  which  have  effectually  ser\'ed  their  pur- 
pose. The  first  prevents  the  jitney  and  motorbus  from 
operating  on  streets  now  served  by  the  street  railway 
system.  The  second  requires  jitneys  to  secure  the  con- 
sent of  fifty-one  per  cent  of  the  property  owners  on 
any  route  upon  which  they  attempt  to  operate.  As  a 
result  of  this  there  are  no  jitneys  operating  legally  in 
Kansas  City  today.  At  this  writing,  about  one  hun- 
dred and  thirty  of  them  are  half-heartedly  attempting 
to  evade  the  law  by  accepting  tips  and  advertising  free 
rides.     They  die  hard,  but  nevertheless  they  are  dying. 

In  Des  Moines,  although  public  opinion  and  a 
large  part  of  the  press  was  incensed  at  the  street  rail- 
way and  was  extremely  unfavorable  yet,  upon  suspen- 
sion of  street  railway  service,  the  public  and  the  city 
council  refused  to  grant  a  five  j^ear  franchise  to  motor- 
bus  companies.  Such  motorbus  transportation  as  the 
city  has  is  a  failure  as  far  as  moving  the  people  com- 
fortably and  efficiently  is  concerned.  This  fact  is 
recognized  in  Des  Moines.  The  people  there  are 
almost  a  unit  in  admitting  that  the  transportation  busi- 
ness of  the  city  cannot  adequately  be  furnished  by  the 
motorbus.  As  a  result  of  this,  grudgingly  though  it 
may  be,  some  favorable  franchise  will  be  granted  to 
the  traction  interests. 

Now  the  trend  of  discussion  seems  to  be  along  the 
line  that  street  railways  should  avail  themselves  of  the 
motorbus  as  an  auxiliary  and  subsidiary  form  of  trans- 
portation. Motor  companies  are  pushing  this  propa- 
ganda, and  while  it  may  be  necessary  and  advantageous 
in  certain  localities,  yet  this  is  a  field  in  which  haste 
had  better  be  made  slowly.  There  is  a  danger  in  the 
industry  as  a  whole  of  pushing  the  bus  propaganda 
too  vigorously.  There  is  every  danger  of  demands  be- 
ing made  upon  us  which  we  are  unable  to  meet.  If  a 
few  busses  are  placed  in  one  section  of  any  city  to 
serve  as  feeders  to  an  established  line,  there  is  every 
likelihood    that    immediate    demands    will    come    from 


other  sections,  with  the  result  that  we  will  be  attempt- 
ing to  supply  almost  a  taxicab  service. 

Many  of  our  cities  are  today  over-tracked  rather 
than  under-tracked,  and  further  expense,  even  if  in  the 
nature  of  trackless  trolleys  or  motorbusses,  may  be  the 
means  of  furnishing  service  at  an  expense  which  would 
not  be  justified  by  the  revenue  derived. 

There  is  every  indication  that  our  cities  are  now 
awake  to  the  dangers  of  this  competition.  As  between 
a  good,  efficient  car  system  and  a  combination  of  cars 
and  competing  busses,  neither  adequate,  they  will 
choose  the  former.  The  public,  knowing  that  the  pre- 
servation of  adequate  street  railway  service  is  abso- 
lutely essential,  will  not  permit  competition  to  ruin  it. 
All  signs  point  to  a  lessening  of  this  evil  and  very  soon 
the  second  chapter  on  jitney  competition  in  the  Ameri- 
can street  railway  industry  will  probably  be  concluded. 


An  Appeal  to  Manufacturers  and 
Dealers 


A 


BARRON  G.  COLLIER 

Chairman,  Committee  of  Publicity, 
American  Electric  Railway  Association 

S  AN  advertising  man  I  believe  that  the  outlook 
from  the  manufacturers'  and  dealers'  standpoint 
should  be  more  encouraging  than  it  has  been  in 
several  years.  A  very  large  part  of  the  advertising 
and  publicity  work  done  in  behalf  of  the  industiy  sure- 
ly will  redound  to  the  direct  benefit  of  the  sellers  of 
electric   railway  supplies. 

One  point  that  has  been  driven  home  strongly  by 
the  advertising  section  of  the  American  Electric  Rail- 
way Association,  is  that  fair  treatment  of  electric  rail- 
ways is  essential  to  extensions  and  betterments  on  the 
lines.  Naturally,  the  public,  reacting  to  this  appeal  for 
a  square  deal  for  electric  railways,  will  want  better- 
ments and  extensions,  and  when  they  come  the  maker 
of  and  dealer  in  supplies  will  be  the  direct  beneficiary. 
Thousands  of  pieces  of  literature  and  hundreds  of 
columns  of  newspapers  articles  dealing  with  the  need 
of  money  for  betterments  and  extensions  have  reached 
the  public  in  the  last  year.     More  of  it  is  coming. 

Manufacturers  and  dealers  can  do  much  to  help 
the  industry  by  seeing  that  their  employes  and  others 
with  whom  they  come  in  contact  receive  and  read  this 
material.  Many  channels  are  available  for  its  distri- 
bution which  have  never  been  used.  The  public  will 
learn  the  truth  about  the  electric  railway  only  so  rapid- 
ly as  the  truth  is  put  before  it  and,  in  turn,  buying  of 
materials  and  supplies  will  pick  up  in  exact  ratio  to  the 
speed  with  which  the  public  becomes  cognizant  of  the 
truth  and  extends  fair  treatment  to  the  roads. 

May  we  earnestly  urge  your  help  and  co-operation 
in  helping  us  to  disseminate  this  thought — distribu'e 
through  every  means  within  your  reach  advertising 
matter  which  will  co-ordinate  what  we  are  doing  so 
that  the  united  purpose  of  our  messages  will  bring 
about  more  speedily  the  rehabiliation  of  the  industry. 


Efccti'ic  !llaliwny  and   VYolfai'o  Work 


JOSEPH  H.  ALEXANDER 

\'ice-President, 
Cleveland    Railway    Company 


NO  discussion  of  welfare  work,  whether  appHed  to 
industry  in  general  or  to  street  railways  in  par- 
ticular, can  hope  to  receive  much  consideration 
today  unless  somewhere  in  it  we  can  affirmatively  ans- 
wer the  question — "Does  it  Pay." 

Long  ago  I  have  been  convinced  that  our  labor 
must  be  purchased  and  maintained  much  as  our  ma- 
terial and  equipment  is.  It  has  got  to  be  right  and 
reasonably  near  the  correct  specifications  in  the  first 
place,  and,  thereafter,  it  will  respond  to  care  and  to 
reasonable  attention  with  longer  life,  and  better  serv- 
ice during  the  period  of  its  use.  By  longer  life  I  mean 
a  smaller  turnover. 

I  want  particularly  to  bring  out  the  thought,  how- 
ever, that,  notwithstanding  I  am  a  believer  in  welfare 
work  and  social  betterment  of  our  employes,  it  is  my 
opinion  that  no  effort  of  this  kind  will  bring  the  maxi- 
mum of  good  results  un- 
less, under  the  plan  of  in- 
troduction, the  employes 
themselves  do  a  portion 
of  the  work  and,  to  some 
extent  at  least,  initiate  it 
or  carry  it  on.  No  worth- 
while employe  relishes  a 
good  thing  that  is  thrust 
upon  him  so  much  as  he 
does  one  that  he  helps  ob- 
tain for  himself.  No  one 
of  us  likes  to  feel  we  are 
being  patronized.  Good 
labor  relations  will  not 
thrive   under   a    care   that 


An  important  expenditure  of  money  is  not  required, 
and  a  business  policy  which  appreciates  the  value  of 
encouragement  and  expressed  good  will,  and  the 
many  good  things  which  cannot  be  purchased  with 
money,  may  expect  to  meet  in  return  a  policy  on  the 
part  of  its  employes  calling  for  more  than  mere  per- 
functory service  and  one  that  carries  with  it  a  loyalty 
and  good  will  that  increases  year  by  year.  Without 
these  things,  an  employe  is,  of  course,  of  little  real 
value. 

PLANS    FOR    CO-OPERATION    WITH    THE    EMPLOYES    IN 
BETTERING  OPERATING  CONDITIONS 

No  matter  what  our  viewpoint  is,  it  is  my  opinion 
that  there  has  never  been  a  time  so  ripe  as  this  for 
well  directed  welfare  work  along  the  line  of  bettering 
operating  conditions.  It  is  next  to  impossible  for  us 
to  look  at  the  matter  from  any  viewpoint  other  than 
as  dealers  in  transportation 


^•j«  fji  fji  (j^  (jl*  r{i  f^  (^  ^  rJl.  rj^  r^i  p|^  rj" '^'>  <>{^  rj;i  r|;i  r}i  •{*  iJl^  r^ 


IT  is  no  more  difficult  to  promote  wel- 
fare work  on  a  street  railway  system 
than  in  any  other  industry. 

Labor,  somewhat  like  material  and 
equipment,  will  respond  to  care  and  rea- 
sonable attention,  with  longer- life  and 
better  service. 

Welfare  work  which  encourages  em- 
ployes to  help  themselves  will  pay. 


•5f.j(,^.}.j|-.{, .},.},.{,  .J.  .j,.},^.{,^^,j,  .J,  .j,,j,.j,.j,^,j,,j,^,j„j,,j,^^,j,,|,^_j,_j_^_j__j_^ 


amounts  to  coddling.  The  employes  must  have  suffi- 
cient interest  to  push  the  work  themselves  because 
they  recognize  its  value  to  themselves  or  it  will  prove 
to  be  worthless  as  welfare  work. 

Furthermore,  our  welfare  work  should  stand 
mostly  for  operating  perfection,  and  must  be  confined 
more  or  less  to  the  place  of  employment,  and,  to  a 
large  extent,  the  hours  of  employment.  The  employes 
should  be  free  to  live  as  they  please  outside. 

With  those  restrictions  it  has  been  our  experi- 
ence, and  I  think  the  experience  of  every  one  who  has 
undertaken  welfare  work,  that  a  management  which 
year  after  year  proves  its  sincere  good-will  towards 
the  employes  obtains  a  valuable  return,  figurable  in 
money,  by  reason  of  a  decreased  labor  turnover;  and 
reaps  a  large  harvest  of  satisfaction  out  of  the  addi- 
tional loyalty  of  its  employes,  and  from  the  recognized 
benefits  inevitably  accruing  to  the  community. 

It  is  no  more  difficult  to  promote  welfare  work 
on  a  street  railway  system  that  in  any  other  industr}-. 


because  that  is  the  thing 
we  are  in  business  to  sell. 
One  of  the  most  important 
requirements  for  the  mer- 
chandising of  transporta- 
tion to  the  best  advantage 
is  the  rendering  of  an  ex- 
cellent and  courteous  serv- 
vice  to  the  riding  public. 
So  far,  therefore,  as  our 
relations  with  the  riding 
public  are  concerned,  we 
cannot  go  far  wrong  by 
seizing  every  opportunity 
to  better  our  operating 
conditions  to  the  end  of  good  service.  And  further- 
more, I  think  that  just  at  this  time,  and  for  the  next 
few  years  to  come,  efforts  of  this  kind  will  receive 
a  more  obvious  welcome  from  the  car  riding  public 
and  produce  more  outstanding  and  favorable 
and  immediate  results  than  ever  before,  because  the 
peak  of  criticism  against  the  street  railway  industn-  of 
the  country,  which  came  as  a  result  of  the  necessity  for 
universally  increasing  fares,  has  been  passed  and  the 
public  is  rapidly  evincing  a  more  friendlv  attitude  than 
ever  before. 

So  far  as  our  relations  with  our  employes  are 
concerned  these  two  features  are  of  outstanding  im- 
portance : 

The  closer  we  can  draw  to  us  the  lasting'  friendship 
and  loyalty  of  our  employes  and  cooperate  with  them  in 
bettering  our  operating  and  their  working  conditions,  the 
sooner  and  more  readily  will  they  respond  to  our  teach- 
ings and  our  policies  and  render  the  riding  public  the 
courteous  and  intelligent  service  we  are  striving  to  pro- 
vide. 

The   more   we   can   arouse   and   stimulate   on   the   part 


454 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


of  our  employes  a  healthy  interest  in  the  company's  wel- 
fare and  an  appreciation  of  their  own  part  in  it  and  a 
reasonable  contentment  and  pride  and  concern  in  and  for 
their  work,  and  their  cars,  and  their  passengers,  the  more 
assuredly  will  they,  little  by  little,  bend  their  efforts  to- 
wards the  new  and  better  labor  relation  fostered  by  local 
organizations  and  based  on  local  conditions  and  looking 
towards  their  own  mutual  welfare. 

With  the  exception  of  a  short  time,  about  ten 
years  ago,  when  this  company  was  undergoing  re- 
organization, we  have  for  a  period  of  over  fifteen  years 
endeavored  to  gain  the  co-operation. and  the  confidence 
of  our  platform  men  through  rules  providing  for  the 
hearing  of  grievances  and  suggestions  on  the  part  of 
the  men.  The  first  agreement  provided  that  a  com- 
mittee consisting  of  the  ofiicials  of  their  local  organi- 
zation should  present  to  the  Superintendent  at  a  regu- 
lar meeting,  the  time  of  which  was  fixed,  any  individ- 
ual or  other  grievances  relative  to  discipline  or  serv- 
ice and,  in  case  of  an)-  dissatisfaction  as  a  result  of 
the  hearings,  were  given  the  right  of  appeal  to  the 
General  Manager,  and  a  further  right  of  appeal  tr>  the 


matter  may  be  brought  directly  to  the  President  at  a 
regular  meeting  consisting  of  the  President,  the  repre- 
sentatives of  the  man,  the  man  aggrieved  and  any  of 
his  fellow  workers  or  other  company  employes  who 
may  be  concerned  in  the  particular  matter  in  hand,  or 
whose  presence  may  be  needed  properly  to  dispose  of 
the  matter.  The  rules  are  made  by  agreement  between 
the  men  and  the  company,  so  that  when  thev  are  in-, 
fringed  upon  there  is  a  minimum  of  censure  for  the 
company  if  he  is  penalized.  There  have  been  occa- 
sions when  some  schedule  changes  have  been  desired 
b}'  the  men  and  although  generally  when  given  the  task 
cf  working  out  these  changes  they  have  discovered 
their  requests  to  be  not  feasible,  yet,  last  year,  as  a 
result  of  their  requests,  some  changes  were  made  which 
proved  to  be  beneficial  to  them  and  in  no  way  harm- 
ful to  the  company.  I  am  quite  positive  that  these 
committee  meetings  have  gone  a  long  ways  to  make 
our  relations  with  our  platform  men  agreeable  and 
liarmonious,  and  I  believe  that  to  our  efforts  to  fullv 


FIG.    I— Sr.\Xn.\RD  01ER.\T1.\G   SIATION   OF  THE  CLEVEL.\ND  R.MLSVAY  COMP.VXY 


President,  in  case  they  were  still  dissatisfied.  That 
committee  meeting,  which  was  first  inaugurated  with 
only  the  matter  of  discipline  in  mind,  has  been  de- 
veloped to  a  large  extent  and  has  proved  to  be  an  ave- 
nue to  an  unexpected  and  valuable  co-operation  be- 
tween the  management  and  the  platform  men.  Under 
the  original  arrangement  the  grievances  and  demands 
for  appeals  were  so  numerous  and  cases  were  so  con- 
sistently appealed  to  the  President  that  the  intermedi- 
ate appeal  to  the  General  Manager  was  discontinued 
and,  under  the  present  arrangement,  when  the  plat- 
form men  feel  that  a  rearrangement  of  runs  or 
schedules  is  advisable  in  order  to  make  their  work 
easier  or  their  pay  more  uniform,  or  whenever  any 
one  of  them  feels  he  has  been  unduly  punished  or  cen- 
sured or  improperly  dismissed,  or,  in  fact,  has  any 
grievance  at  all  which  the  Transportation  Department 
has    not    dealt    with    to    their    entire    satisfaction,    the 


meet  their  requests  and,  so  far  as  we  can  ascertain 
them,  their  needs  from  time  to  time,  may  be  attributed 
our  successfully  avoiding  two  serious  labor  difficulties 
in  the  last  two  years.  The  company  is  very  strict  and 
very  firm  in  requiring  that  rules  be  obeyed,  but  en- 
deavors in  every  way  to  give  consideration  to  the  .-ug- 
gestions  and  requests  or  the  grievances  of  the  em- 
ployes. 

Ill  our  shops  we  have  never  had  a  similar  means 
of  communicating  with  our  men  but  we  have  been 
unusually  fortunate  in  having  both  as  our  Master  Me- 
chanic and  as  our  foremen  men  who  have  grown  up 
in  the  employ  of  the  company,  and  who  hold  their 
present  positions  through  promotion,  and  there  is  an 
unusual  close  bond  of  friendship  and  obviously  a  strong 
spirit  of  contentment  among  the  men  employed  there, 
which  is  entirely  the  result  of  the  fact  that  they  feel 
at  liberty,  at  any  time,  to  discuss  as  friends  the  matter 


October,   1921 


THE   ELECTRIC  JOURNAL 


455 


of  conditions  or  pay  or  promotion,  or  their  own  per- 
sonal welfare,  as  the  case  may  be.  The  officials  of  the 
company  invariably  endeavor  to  respond  favorably  to 
as  many  of  these  matters  as  eventually  come  to  their 
notice. 

In  other  words,  I  believe  we  have  learned  that  the 
spirit  of  friendship  for  and  among  our  employes  is 
worth  far  more  than  any  entertainment  we  might  pro- 
vide, or  any  gifts  or  expenditures  we  might  make  in 


Ml,    J    -I Ml  liiVKS    B.^RBER  SHOP,  CONFECTIONERY  .\ND  LIGHT  LUNCH 
ROOM 

iheir  behalf  without  requiring  any  effort  on  their  part. 
No  employe  feels  the  sting  of  patronage  when  we  deal 
with  him  as  a  friend.  The  worthwhile  employe  re- 
sents the  thoughts  that  he  must  be  looked  after  as  a 
child.  He  must  be  allowed  to  help  himself.  We  are 
very  cautious  in  this  respect  and  endeavor  to  make 
self-help  and  pride  and  self-respect  and  co-operation 
ihe  controlling  features  of  anything  in  the  nature  of 
welfare  work  which  this  company  encourages. 

CLEANLINESS,   SANITATION,  COMFORT  AND  PRIDE 

I  hardly  believe  it  is  possible  for  any  one  of  our 
employes  to  walk  into  one  of  our  standard  operating 
stations,  or  into  our  shops  .without  feeling  some  pride 
in  the  fact  that  he  is  a  part  of  the  organization  which 
maintains  them.  We  have  tried  to  make  our  operating 
stations  look  as  well  architecturally  as  is  compatible 
with  appropriate  cost  and  service  and  inside  we  have 
attempted  to  provide  every  modern  improvement  and 
convenience. 

Our  shops  and  main  storage  yard  cover  an  area 
of  approximately  thirty-eight  acres,  and  before  the  ma- 
chinery was  installed  every  piece  was  located  on  the 
drawings  and  consideration  given  to  every  comfort 
r'nd  convenience  of  the  men.  The  working  areas  are 
hght,  airy  and  so  arranged  that  orderliness  is  obtained 
?lmost  as  a  matter  of  course.  The  unusual  cleanli- 
ness and  orderliness  of  our  shops  has  been  the  cause 
of  frequent  comment  on  the  part  of  visitors  and  it  is 
nlmost  entirely  due  to  the  thought  and  care  which  was 
given  to  the  location  of  machinery  and  the  room  which 
men  need  to  do  their  work  properly  and  comfortably. 
First  aid  surgeries,  lunch  room,  lockers  and  showers 
are  provided  and  there  is  no  reason  why  an  employe 
should  leave  for  home  looking  other  than  neat  and 
clean  and  refreshed  after  his  days  work. 

We  have  recognized  the  necessity  for  men  spend- 
ing some  time  in  our  operating  stations  at  various  hours 


of  the  day  and  night  just  before  and  just  after  shifts  in 
runs,  and  for  emergency  occasions,  we  have  provided 
sleeping  accommodations  which  they  may  use.  The 
sleeping  rooms  are  approximately  thirty  by  forty-two 
feet  in  size  and  steel  spring  cots  are  used.  These 
rooms  and  the  bedding  are  kept  clean  and  neat  and 
ready  for  inspection  at  any  hour  of  the  day  or  night. 
A  portion  of  the  cots  are  provided  only  with  mattresses 
and  blankets  and  pillow,  while  others  are  provided  with 
white  sheets  in  addition.  Those  men  who  wish  only  to 
rest  for  a  short  period  and  who  do  not  remove  their 
shoes  or  outer  clothing  use  the  cots  which  are  provided 
only  with  the  blankets,  but  always  we  insist  on  the 
utmost  cleanliness  and  care  to  keep  the  rooms  whole- 
some and  fit  for  occupancy. 

Space  is  furnished  in  which  the  men  may  place 
pool  tables  which  they  have  purchased  through  their 
club  organization, — an  organization  which  we  encour- 
age in  every  respect,  and  they  have  in  every  case  taken 
advantage  of  this  and  seldom  do  you  find  the  tables 
unoccupied.  For  their  convenience  space  is  also  given 
over  to  a  barber  shop  and  confectionery  and  light  lunch 
counter,  and  the  prices  charged  at  these  places  are  kept 
under  close  supervision. 

We  are  very  proud  of  the  type  of  men  to  be  found 
on  our  street  cars  and  in  our  shops,  and  of  the  manner 
in  which  almost  invariably  we  find  them  endeavoring 
to  live  up  to  the  spirit  of  our  instructions.  We  have 
some  employes  who  have  been  with  us  for  a  period 
of  from  twenty  to  thirty  years,  and  a  much  larger 
number  for  ten  years  or  more.  These  facts  have  a  di- 
rect bearing  on  our  expenses  in  several  ways:  for  in- 
stance, we  find  our  percentage  of  accidents  much 
higher  among  new  men  than  among  old  employes. 
I'o  take  a  concrete  example,  during  the  last  two  years 
we  have  averaged  nine  accidents  per  man  per  vear  in 
our  first  year  group  of  platform  men,  and  an  average 
of   four  accidents  per  man  per  year  in  the  group  of 


FIG.  3 — POOL  ROOM  FURNISHEn  AND  MAINTAINED  BY  EMPLOYES' 
CLUB  ORGANIZATION 

platform  men  who  have  been  employed  ten  vears  or 
more.  From  the  standpoint  of  claims  made  alone,  and 
ignoring  entirely  the  matter  of  repairs  to  our  own 
equipment  and  loss  of  time  for  both  men  and  equip- 
ment, our  accidents  have  averaged  in  the  neighborhood 
of  $50  each.  That  would  amount  to  $450  per  man  per 
year  if  we  had  a  100  percent  labor  turnover  each  year 


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THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


and  but  $200  a  year  if  all  our  employes  had  been  with 
us  for  over  ten  years.  In  other  words,  on  the  basis  of 
3000  platform  men,  it  would  cost  us  $1  350000  a  year 
if  we  continually  had  new  men  on  the  job  and  we  could 
apparently  reduce  this  to  $600000  and  thus  save 
$750000  a  year  if  all  our  employes  were  ten  year  men. 
These  figures  give  one  concrete  example  of  a  sav- 
ing which  can  be  directly  traced  and  attributed  to  the 
platform  man's  satisfaction  with  his  job.  It  can  be 
traced  directly  to  our  eflforts  to  bring  about  that  con- 
dition of  affairs.  Whenever  we  have  given  a  man  a 
car  he  is  proud  to  operate  and  ride  upon ;  and  an  oper- 
ating station  that  compares  favorably  with  any  build- 
ing in  the  neighborhood;  and  when  we  have  seen  to  it 
that  he  and  all  his  fellows  are  dressed  in  a  manner 
which  enhances  that  pride  in  his  work;  and  as  often 
as  we  have  brought  home  to  him  the  fact  that  he  is  our 
one  point  of  contact  with  the  car  riding  public  and 
that  it  is  upon  him  we  must  depend  for  the  good  will 
of  the  public  towards  us  and  him;  at  those  times  we 
have  been  directly  contributing  to  his  contentment  and 
satisfaction  with  his  work  and,  in  direct  proportion,  to 
our  own  bank  account. 


^11             F*n 

FIG.  4 — FIRST  .\ID  SURGERY 

Those  figures,  of  course,  relate  solely  to  one  ele- 
ment of  direct  loss  from  labor  turnover  and  ignore 
even  the  cost  of  schooling  a  new  man  and  the  in- 
tangible annoyances  which  every  new  man  causes  when 
he  is  being  trained  in  the  early  stages  of  his  employ- 
ment. They  are  cited  simply  to  prove  that  we  can 
find  some  tangible  ways  in  which  wise  welfare  work 
will  pay. 

A  FUTURE  WHICH  AN  EMPLOYE  CAN  VISUALIZE 

It  is  difficult  for  many  of  us  to  appreciate  how 
different  our  viewpoint  is  from  that  of  the  men  who 
are  employed  by  us  as  mechanics  and  on  our  cars.  We 
have  grown  to  look  upon  provisions  for  our  future, 
such  as  insurance  and  investments,  as  a  matter  of 
course.  Some  of  us  are  even  wise  enough  to  give  some 
consideration  to  the  manner  in  which  we  eat  and  live. 
Many  of  our  employes  have  neither  the  wisdom  nor  the 
provident  inclinations  properly  or  effectively  to  take 
care  of  these  things  even  though  they  appreciate  the 
value  and  necessity  for  doing  so.  And  yet  our  em- 
ployes, and  particularly  our  older  and  more  stable  and 


contented  emplo3'es,  are  such  an  asset  to  us  that  we 
cannot  afford  to  allow  them  to  ignore  their  health,  their 
future,  nor  their  family's  welfare  after  they  are  gone. 

HEALTH    INSURANCE — SUPERANNUATION 

Mr.  E.  J.  Doran,  Traffic  Manager  for  the  New 
South  Wales  Government  Tramways,  aroused  a  con- 
siderable amount  of  my  interest  when  he  visited  our 
property  some  months  ago  and  among  other  things  ex- 
plained their  method  of  providing  a  form  of  insurance 
or  retiring  fund  for  their  employes.  Their  idea  is,  of 
course,  not  a  new  one,  but  was  so  effective  and  from 
bis  account  of  its  workings  so  satisfactory  to  everyone 
concerned  that  I  obtained  a  copy  of  the  New  South 
Wales  law  making  these  provisions  and  found  it  very 
interesting.  Under  their  plan  a  deduction  of  1.5  per- 
cent of  their  salaries  is  made  from  time  to  time  and  the 
fund  thus  created,  together  with  a  like  amount  contri- 
buted by  the  Railway,  is  placed  to  the  credit  of  a  spe- 
cial account  in  the  government  treasury  and  called  the 
Government  Railways  Superannuation  Account.  A 
man  who  is  over  sixty  and  has  retired  after  ten  years 
or  more  of  service  or,  who  is  under  sixty  and  has, 
after  ten  years  of  service,  been  compelled  to  discon- 
tinue work  through  infirmity  or  for  any  other  reason, 
is  entitled  to  a  superannuation  allowance  which  is  pay- 
able every  year  for  the  rest  of  his  life.  The  allowance 
amounts  to  one-sixtieth  of  an  average  taken  of  his 
earnings  during  his  temi  of  service  multiplied  by  the 
number  of  years  of  his  service. 

There  are  similar  methods  in  use  in  our  own 
country  and  it  is  my  opinion  that  such  a  provision  is 
not  complete  without  oft'ering  him  an  opportunity  for 
obtaining  a  reasonable  amount  of  inexpensive  insur- 
ance. 

It  would  surprise  a  great  many  to  know  how  many 
of  their  employes  who  are  apparently  well  and  healthy 
are  really  far  below  par.  Fifty  percent  is  a  low  esti- 
mate. You  will  recall  that  thirty-three  percent  of  the 
young  men — men  between  twenty-one  and  thirty-one — 
were  rejected  for  the  army.  I  have  never  yet  dis- 
covered a  way  which  seems  satisfactory  to  me  for  help- 
ing a  man  maintain  his  health  up  to  a  point  reasonably 
near  a  proper  standard.  We  all  seem  to  resent  an  out- 
side supervision  or  effort  to  tell  us  we  should  not  eat 
this  or  that  food,  or  indulge  in  this  or  that  form  of 
work  or  recreation.  Yet  health  is  the  greatest  asset 
which  our  employes  have  and  our  employes  in  turn  can 
be  made  the  greatest  asset  we  possess.  I  have  recently 
given  some  study  to  a  plan  along  this  line  which 
comes  nearer  the  result  desired  than  anything  I  have 
yet  found.  The  reason  this  plan  seems  to  meet  the 
need  best  is  that  it  attempts  to  interest  the  employe 
himself  in  his  health  and  the  plan  is  offered  to  him  in 
the  nature  of  an  opportunity  and  not  forced  upon  him. 
The  plan  seems  to  be  founded  on  the  realization  that 
the  employe  must  pay  part  of  the  expense  in  order  to 
appreciate  the  value  of  the  service  received.  If  a  per- 
son pays  for  something  he  naturally  wants  to  get  some- 


October,  1921 


THE   ELECTRIC  JOURNAL 


457 


thing  for  his  money.  The  only  way  he  can  get  any- 
thing is  by  following  out  the  suggestions  made  by  the 
doctor.  Under  this  plan  a  man  who  pays  twenty-five 
cents  a  week  or  thirteen  dollars  a  year,  with  his  em- 
ployer paying  a  like  amount,  can  obtain  $1000  life  in- 
surance, $io  a  week  health  and  accident  insurance,  and 
a  health  supervision  and  service  of  real  value.  By 
paying  slightly  more,  those  employes  who  desire  can 
obtain  more  insurance  and  larger  weekly  Jiealth  and 
accident  payments.  The  plan  thus  offers  an  opportun- 
ity not  only  to  provide  against  accident  and  death,  but 
to  guard  against  the  development  of  disease  and  up- 
build the  vitality  and  improve  the  general  physical  con- 
dition. I  do  not  think  that  a  plan  has  yet  been  devised 
which  will  actually  succeed  in  making  men  take  proper 
care  of  themselves.  But  any  plan  which  does  not  give 
the  employe  something  for  nothing  and  which  makes 
them  pay  a  reasonable  price  for  it  and  tends  to  educate 
them  to  the  need  for  it  and  encourages  them  and  helps 
them  to  acquire  it  without  it  being  burdensome  to  them, 
comes  very  near  to  being  an  ideal  plan  for  maintaining 
at  the  highest  possible  standard  this  asset  which  is  too 
valuable  for  us  to  be  entirely  ignored. 

HOME  BUILDING  FUNDS  OR  CREDITS 

Some  months  ago,  when  the  matter  of  inadequate 
housing  was  viewed  as  a  serious  matter  in  almost  every 
city  in  the  United  States,  the  City  Council  of 
Cleveland  passed  a  resolution  to  the  effect  that  the 
Cleveland  Railway  Company  should  be  permitted  to 
lay  aside  a  fund  from  which  loans  might  be  made  to 
employes  for  the  building  of  homes  under  certain  rea- 
sonable   restrictions.      The    general    financial    situation 


made  it  impossible  for  us  to  accept  this  suggestion  on 
the  part  of  the  City  Council,  but  the  fact  remains  that 
every  property  of  sufficient  size  to  enable  it  to  handle 
a  fund  and  manage  a  series  of  loan  accounts  of  this 
kind  would  be  doing  more  for  their  employes  and  for 
themselves  and  for  the  community  than  many  realize. 
A  good  citizen  is  a  good  employe  to  have  in  your  or- 
ganization. A  man  who  owns  or  is  acquiring  his  own 
home  makes  a  better  citizen  and  a  more  stable  and 
steady  and  valuable  employe.  I  do  not  know  when 
our  own  management  will  feel  in  a  position  to  recom- 
mend a  plan  of  this  kind,  but  it  is  a  thing  which  we 
should  keep  in  mind  and  which  every  business  organi- 
zation and  large  employer  should  carefully  investigate, 
always  bearing  in  mind  the  fundamental  requirements 
in  this,  as  in  every  other  bit  of  help  or  welfare  work 
that  is  offered : — the  employe  must  be  merely  offered 
the  opportunity  to  do  something  himself.  We  must 
appreciate  that  we  do  more  hann  than  good  when  we 
tell  our  employes  we  are  going  to  give  them  something. 
Although  some  may  appreciate  what  we  are  doing,  the 
majority  are  most  likely  not  to  do  so. 

I  am  convinced  that  where  welfare  work  consists 
of  co-operation  with  our  employes  in  lieu  of  help,  and 
where  friendship  is  obviously  the  basis  on  which  that 
co-operation  is  offered,  welfare  work  does  pay.  It 
pays  from  the  standpoint  of  money  saved;  from  the 
employes'  higher  standard  of  self-respect  and  better 
physical  condition.  And  futhermore,  our  own  feeling 
of  pride  in  our  employes,  and  in  the  work  we  are  doing 
for  the  community,  will  in  themselves  prove  of  suffi- 
cient value  to  make  that  sort  of  welfare  work  worth 
our  while. 


^ ,  \  I 


Tho  iVobloid  c)f  .Sirooc  CoiljjDStloa 


STREET  congestion  brings  out  more 
than  any  other  urban  problem  the  greatest 
strength  and,  at  the  same  time,  the  greatest 
weakness  of  electric  railway  service.  Its  strength  is 
shown  by  the  superiority  of  electric  railway  facilities 
in  economy  and  capacity  for  carrying  large  numbers 
of  people  over  long  urban  distances.  There  is  no 
other  form  of  transportation  which  can  supply  the  de- 
mand for  urban  transportation  at  a  price  within  the 
ability  of  the  general  traffic  to  bear,  and  the  basis  of 
this  cheapness  is  the  tendency  of  large  numbers  of 
people  to  travel  at  the  same  time.  Almost  any  other 
form  of  transportation— automobile,  auto-bus,  horse- 
drawn  vehicle  or  walking— would  be  more  economical 
for  individual  movements  from  place  to  place,  on  ac- 
count of  the  expensive  investment  necessary  to  pro- 
vide electric  railway  service. 

Unfortunately  this  fundamental  basis  for  our  in- 
■dustr}'   carries   with   it  the   compensating  weakness  of 


THO.MAS  FITZGERALD 

Consulting  Electric  Railway  Engineer, 
Pittsburgh.  Pa. 

forcibly  impairment  in  quality  of  service.  In  many  communi- 
ties, a  condition  of  congestion  has  been  reached  where, 
in  the  minds  of  the  car  riders,  the  value  of  the  service 
is  below  the  small  charge  for  it. 

There  are  two  avenues  of  attacking  this  problem; 
one  is  to  convince  the  car  riders  that  the  service  is 
worth  the  price,  the  other  to  reduce  the  avoidable  con- 
gestion, both  in  the  cars  and  on  the  streets,  in  order  to 
counteract  so  far  as  possible  the  impairment  to  service. 
Neither  of  these  methods  is  independent  of  the  other. 
In  order  to  convince  the  public  that  the  price  is  right, 
they  must  first  be  convinced  that  the  management  is 
doing  everything  in  its  power  to  improve  service;  and 
many  changes  in  service  will  be  impossible  unless  the 
public  feels  that  the  price  is  right. 

This  brings  out  the  principal  factor  in  the  prob- 
lem,— the  relation  between  the  railway  management 
and  the  public.  With  reasonably  good  relations,  nec- 
essary changes  in  operating  methods,  routes,  track  and 


458 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


equipment  productive  of  improvement  will  be  compara- 
tively easy. 

The  importance  of  this  problem  indicates  the  fact 
that  its  solution  involves  nearly  e\ery  angle  of  rail- 
way management. 

/ — As  noted  above,  public  relations  will  determine 
largely  the  success  or  failure  of  efforts  to  make  neces- 
sary changes. 

2 — A  strong  financial  position  will  make  possible 
expensive  changes  in  track,  ecjuipnient  and  operating 
methods. 

2 — Good  operating  methods  must  follow  good 
public  relations  and  a  strong  financial  position,  if  these 
are  to  be  maintained  and  improved. 

Mention  of  a  few  of  the  details  which  enter  into 
the  solution  of  this  problem  may  be  of  some  help  in 
understanding  its  scope  and  complexity.  There  is  no 
single  change  or  methf^d  through  which  radical  benefi- 
cial results  may  be  secured.  Nearly  all  of  the  princi- 
pal influences  in  this  problem  are  interrelated  in  such 
a  way  as  to  require  a  broad  consideration  of  many  in 
connection  with  even  minor  changes. 

The  first  idea  which  naturally  suggests  itself  is 
the  reduction  of  interference  by  other  vehicular  traffic 
with  street  car  operation.  Suggestions  along  this  line 
range  all  the  way  from  double-decked  streets  and  sub- 
ways to  effective  control  of  traffic  under  present  con- 
ditions. It  may  be  that  a  second-story  street  for  light 
vehicles  and  pedestrians  in  the  over-congested  districts 
is  a  solution  of  our  problem ;  this  is  not  clear  at  pres- 
ent. Double-decked  streets  and  bridges  are  not  un- 
known, so  that  the  proponents  of  this  idea  have  some 
basis  for  their  opinion.  Surface  car  subways  and  ele- 
vated tracks,  taking  surface  cars  out  of  street  conges- 
tion, have  afforded  some  relief.  The  difficulty  in  this 
method  is  to  distribute  the  burden  of  expense  properly 
over  the  other  beneficiaries  of  such  facilities.  Usually 
the  car  rider  cannot  carry  the  burden  alone. 

Less  directly  but  just  as  effectively,  rapid  transit 
subways  or  elevated  lines  will  lift  from  the  surface 
system  sufficient  passenger  traffic  to  bring  relief.  A 
rapid  transit  elevated  or  subway  system  which  may  be 
used  as  a  trunk  line  into  which  surface  cars  transfer 
their  traffic  after  a  short  haul,  would  produce  good 
results  for  a  number  of  our  large  cities.  The  prob- 
lem here  is  to  relieve  the  car  rider  from  carrj-ing  the 
entire  burden  of  expense  and  to  place  a  part  of  the 
burden  on  other  beneficiaries  of  such  a  facility.  It  is 
conceivable  that  the  over-congestion  problem  w-ill  be- 
come so  acute  as  to  force  public  co-operation  in  the 
construction  of  facilities  which  will  transfer  the  pas- 
senger traffic  in  the  over-congested  districts  from  the 
streets  to  a  subway  or  railway  system. 

There  are  intersections  of  streets  where  the  sepa- 
ration of  the  grades  of  the  two  intersecting  streets 
could  be  made.  However,  such  cases  are  compara- 
tively rare  and  would  not  allow  cars  or  vehicles  to  turn 
from  one  street  to  the  other,  unless  one  street  were  ex- 
ceptionally wide. 


Broad  developments  of  city  plans  for  the  establish- 
ment of  through  vehicular  routes,  and  by-passes  around 
the  business  district,  so  located  and  arranged  as  to  at- 
tract traffic  from  the  over-congested  streets  and  rail- 
ways, promise  some  relief.  In  a  great  many  cities  the 
bad  condition  of  the  paving  in  trackless  streets,  coupled 
with  the  good  path  offered  by  the  rails  for  heavy  truck 
traffic,  brings  about  an  unbalanced  condition  of  traffic 
with  too  much  on  the  railway  streets,  too  little  on  the 
trackless  streets  and  additional  interference  on  the 
streets  used  as  detours  from  the  bad  paving  to  the 
tracks  and  back  again. 

Narrow  streets  form  probably  the  worst  cause  of 
street  congestion.  Where  the  street  car  traffic  is  light 
enough  to  permit  the  cars  on  these  streets  to  be  oper- 
ated over  one  track  in  the  same  direction,  one-way  di- 
rection for  traffic  will  relieve  congestion.  Where 
street  car  traffic  requires  more  cars  than  the  capacity 
of  a  single  track,  one-way  operation  will  increase  street 
car  congestion.  Aside  from  one-way  operation,  about 
the  only  method  of  increasing  the  capacity  of  narrow 
streets  is  to  widen  them.  The  suggestion  has  been 
made  to  convert  the  entire  sidewalks  of  such  streets 
into  vehicular  roadways,  and  provide  sidewalks  by 
means  of  arcades  under  the  second  floors  of  the  abut- 
ting property.  This  proposition  is  not  so  visionary  as 
some  other  ideas  which  have  been  seriously  advocated 
and  in  many  instances  it  would  provide  considerable 
relief  at  less  cost  than  a  complete  program  of  widening. 
Coupled  with  this  suggestion  is  one  to  provide  arcades 
through  the  middle  parts  of  downtown  blocks  from  one 
street  to  the  other.  We  have  practical  examples  of 
this  kind  of  facility,  which  relieve  the  sidewalks  of 
some  of  their  pedestrian  traffic. 

A  considerable  feature  of  traffic  congestion  at 
street  corners  is  the  pedestrian  traffic.  Perfect  con- 
trol involves  delaj'S  to  pedestrians  waiting  for  traffic 
signals.  To  provide  for  a  serious  condition  of  this 
kind,  subways  similar  to  those  used  by  the  railroads 
to  permit  passengers  to  pass  from  one  station  under 
the  tracks  to  another  station  might  be  used  to  advan- 
tage. A  subway  of  this  kind  under  an  entire  street 
intersection  could  provide  for  the  free  flow  of  ped- 
estrian traffic  in  all  directions,  without  interference  to 
street  traffic. 

The  full  capacity  of  present  streets  is  not  used 
now,  either  on  account  of  legal  obstacles,  poor  traffic 
regulations  or  failure  to  enforce  regulations.  Public 
opinion  still  insists  that  property  owners  have  the  right 
of  practically  unrestricted  ingress  and  egress,  regard- 
less of  others  dependent  upon  the  free  flow  of  traffic  m 
the  streets  for  their  well  being.  The  extension  of  the 
police  power  in  New  York  to  prevent  the  eviction  of 
tenants  and  in  Kansas  to  prevent  stoppage  of  industrial 
operations  would  seem  to  indicate  that  some  day 
vehicles  will  be  prevented  from  interfering  to  such  an 
unreasonable  extent  as  they  do  now  with  the  comfort 
and  convenience  of  thousands  of  people  for  the  bene- 
fit of  a  very  few.     When  the  public  thoroughly  under- 


October,  1921 


THE  ELECTRIC  JOURNAL 


459 


stands  this  feature  of  the  interference,  the  congestion 
in  street  traffic  caused  by  unnecessary  stoppage  of 
vehicles  will  end.  The  fact  that  some  inadequate  ordi- 
nances have  been  passed  to  prevent  parking  and  even 
the  operation  of  vehicles  at  certain  locations  and  at 
certain  times  indicates  that  the  public  is  beginning  to 
realize  the  justice  of  the  car  riders'  complaint. 

The  strict  enforcement  of  adecjuate  ordinances 
would  go  a  long  way  toward  increasing  the  present  ca- 
pacity of  our  streets.  The  size  of  motor  vehicles 
which  may  be  operated,  through  the  congested  district 
at  least,  should  be  limited  so  as  to  prevent  undue  inter- 
ference with  traffic.  The  presence  of  horse  drawn 
\ehicles  in  over-congested  areas  is  the  worst  example 
of  sacrificing  the  welfare  of  many  to  the  narrow  in- 
terest of  a  few.  Nothing  can  do  more  to  make  ineffec- 
tive the  efforts  of  those  engaged  in  trying  to  move 
traffic  promptly.  Delivery  vehicles  unloading  while  on 
tracks,  and  obstructions  on  the  sidewalk  forcing  ped- 
estrians into  the  streets,  should  not  be  permitted. 

A  free  flow  of  all  other  traffic  in  the  congested 
streets  of  our  cities,  however,  will  not  satisfy  the  car 
rider.  There  are  other  factors  in  the  problem  which, 
in  many  cities,  would  bring  about  over-congestion  of 
car  traffic,  even  if  all  other  vehicles  were  excluded 
from  the  streets.  The  first  limiting  feature  would  be 
interference  of  cars  with  each  other. 

The  capacity  of  tracks  for  loading,  unloading  and 
transporting  passengers  is  limited.  The  maximum 
number  of  cars,  including  a  proportion  of  two  and 
three  car  trains,  that  can  be  dispatched  regularly  over 
a  single  track  with  heavy  loading  is  less  than  two- 
hundred  cars  per  hour  even  in  a  subway  free  from  in- 
terference by  other  vehicular  and  pedestrian  traffic. 
The  number  of  cars  which  can  be  dispatched  over  a 
city  street  will  depend  upon  the  traffic  conditions  and  a 
number  of  other  factors  mentioned  below.  Under  the 
most  favorable  conditions,  which  do  not  include  the 
concentrated  loading  at  one  point  found  in  subway 
stations,  somewhat  less  than  one-hundred  and  seventy- 
five  cars  per  hour  can  be  operated.  A  successful 
schedule  under  the  most  favorable  conditions  of  one- 
hundred  and  fifty  cars  per  hour  may  be  expected. 
From  this  figure  the  possible  effective  schedule  drops 
rapidly  with  the  adverse  street  conditions.  The  actual 
maximum  scheduled  capacity  of  any  single  track  can 
be  determined  only  by  experience  and  observation. 

The  point  is  that,  with  heavily  congested  traffic, 
all  of  the  reasonable  changes  in  the  use  of  streets  to 
allow  more  effective  operation  of  street  cars  will  not 
solve  the  problem  of  street  car  congestion.  Aside 
from  congestion  due  to  other  causes,  the  congestion 
from  street  car  operation  alone  demands  radical 
changes  in  methods.  In  many  cases  surface  car  sub- 
ways, even  liberally  assisted  by  general  taxation,  can- 
not solve  the  problem.  An  adequate  system  of  this 
kind,  on  account  of  its  enormous  expense  and  limited 
capacity  as  compared  with  a  large  capacity,  high-speed 
system,  would  be  at  best  a  poor  makeshift. 


The  establishment  of  business  centers  remote  from 
the  central  business  area  has  undoubtedly  provided 
some  relief  from  central  congestion.  This  tendency 
toward  decentralization,  brought  about  largely  by  con- 
gestion in  the  center,  brings  about  a  demand  for  rapid 
transit  which  will  in  turn  accelerate  the  distribution  of 
business  activities  over  a  wider  area.  Office  buildings 
miles  apart,  located  near  rapid  transit  stations,  are 
closer  in  time  than  those  not  so  served,  which  are  only 
a  few  blocks  apart.  Ideal  urban  passenger  carrying 
facilities  would  include  a  high-speed,  large-capacity 
system  along  the  axes  of  traffic  in  the  industrial,  com- 
mercial and  residential  districts,  with  surface  car 
radials  connecting  with  and  feeding  the  large  capacity 
system. 

In  addition  to  the  general  situation,  there  are  a 
number  of  features  in  the  actual  conditions  which 
should  be  studied  in  each  particular  case.  The  first 
essential  is  service.  Routing  should  be  such  as  to  pro- 
vide the  desired  transportation  with  the  greatest  dis- 
patch and  least  discomfort  for  the  car  rider.  Transfer 
of  passengers  should  be  avoided  if  possible,  but  where 
transfers  will  provide  generally  more  attractive  serv- 
ice than  through  operation,  changes  in  routes  requiring 
transfers  should  be  adopted. 

Many  systems  are  over-congested  on  account  of 
the  locations  of  routes.  Routes  from  different  sections 
cross  and  recross  other  routes  and  other  traffic 
throughout  the  over-congested  districts.  The  history 
of  such  routing  makes  any  rearrangement  particularly 
difficult.  In  many  cases  traffic  has  developed  largely 
on  account  of  the  location,  and  any  change  in  such 
routes  brings  forcible  antagonism.  Owners  of  large 
stores  who  believe  that  their  prosperity  depends  upon 
the  business  brought  to  their  doors  by  present  routes 
may  be  expected  to  exert  their  influence  against  any 
change.  The  argument  that  a  general  improvement  in 
car  service  will  benefit  them  more  than  the  maintenance 
of  their  special  ineft'ective  service  does  not  carry  much 
more  weight  to  them  than  an  appeal  to  the  average  man 
to  sacrifice  what  he  considers  his  own  welfare  to  the 
general  good.  Public  opinion,  however,  has  in  the  past 
forced  changes  in  routing  for  the  general  benefit  of  the 
community  and  of  the  car  rider,  so  that  we  may  be 
hopeful  for  such  changes  in  the  future.  They  may  not 
be  all  that  they  should  be  but,  properly  directed,  w-ill 
produce  some  benefit. 

A  usual  suggestion  for  the  relief  of  congestion  is 
to  route  lines  through  the  over-congested  district  from 
one  outlying  section  to  another.  The  usual  objection 
of  unbalanced  traffic  on  the  outer  ends  is  not  strongly 
supported  by  those  cities  which  have  used  this  method. 
As  a  general  proposition,  the  surplus  service  on  one 
end  has  stimulated  traffic  to  such  an  extent  as  to  bring 
about  a  fair  balance,  so  that  excess  mileage  or  deficient 
service  on  one  end  or  the  other  has  been  reduced  to  a 
minimum.  The  most  forcible  objection  to  through 
routing  is  the  limited  traffic  capacity  of  streets  in  the 
over-congested  area.     In   many  cases  through  routing 


460 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  10 


might  benefit  the  present  situation  temporarily,  but 
it  seems  a  temporary  make-shift,  and  will  establish  cur- 
rents of  passenger  traffic  which  will  be  hard  to  divert 
or  transfer  when  the  over-congestion  in  the  central  dis- 
trict prevents  successful  through  operation.  This 
time,  in  most  large  cities,  is  not  far  off  and  it  will  be 
more  difficult  to  re-route  through  lines  out  of  conges- 
tion than  to  move  back  lines  looping  back  in  the  con- 
gested district.  Through  routing  also  involves  possible 
complications  in  fare  collection  systems  on  some  sys- 
tems, causing  congestion  which  would  counteract  any 
improvement  that  might  be  made. 

Assuming  that  through  routing  is  generally  not  a 
wise  expedient  for  the  relief  of  over-congestion,  the 
best  method,  aside  from  radical  measures  such  as  sub- 
ways or  elevated  systems,  seems  to  be  to  route  cars 
so  as  to  reduce  congestion  to  the  least  point,  consistent 
with  the  best  quality  service  to  the  car  rider.  In  many 
cities,  car  service  for  comparatively  long  distances  has 
become  slower  than  a  walk,  with  frequent  blockades. 
The  car  rider  must  choose  between  slow  irregular  ex- 
pensive service  direct  from  origin  to  destination  and 
faster  service  to  and  from  the  edge  of  the  over-con- 
gested district.  To  supplement  this  service,  continua- 
tion transfer  service  on  short  cross-district  connecting 
lines  through  the  over-congested  streets  must  be  estab- 
lished. The  inconvenience  of  transferring  or  walking 
will  mean  no  more  than  at  present  for  a  large  number 
of  car  riders.  The  balance  of  the  traffic  can  be  handled 
more  effectively  through  the  over-congested  district  on 
a  smaller  number  of  cars  routed  through,  avoiding  the 
interference  to  traffic  due  to  turn  backs  and  to  the  ex- 
cess cars  not  justified  by  the  traffic. 

Unnecessarily  extensive  changes  along  this  line 
are  inadvisable.  Wherever  street  conditions  can  be 
produced  which  will  allow  cars  to  run  through  from 
the  origin  to  the  destination  of  their  passengers,  no 
change  should  be  made;  but  where  the  general  effec- 
tiveness of  the  service  and  proper  economy  in  operation 
require  changes  in  routes,  that  the  general  policy  of 
turning  lines  short  of  the  over-congested  district  with 
short  connecting  lines  through  that  district  will  bring 
the  best  results.  No  fixed  policy  to  determine  the 
proper  action  in  ever)'  case  can  be  laid  down.  Some 
conditions,  notably  over-concentration  of  loading, 
would  make  such  procedure  inadvisable. 

The  principal  symptom  of  the  disease  of  over-con- 
gestion is  slow  operation  with  its  resultant  excessive 
costs  and  irritation  to  the  public.  A  sure  cure  would 
be  to  eliminate  all  street  car  traffic,  just  as  the  ampu- 
tation of  the  head  would  surely  cure  a  stomach  ache; 
but  the  net  result  would  be  business  death.  First,  in- 
vestigate the  causes  of  over-congestion  and  then  apply 
such  remedies  as  promise  to  improve  general  conditions 
without  impairing  the  general  usefulness  of  our  rail- 
ways. Mistakes  will  undoubtedly  be  made,  but  a  cer- 
tain number  of  mistakes  are  inseparable  from  human 
activities  and  must  be  expected  in  any  big  effort  for 


improvement.  Co-operation  and  well  intentioned  criti- 
cism are  needed  to  reduce  mistakes  to  a  minimum  and 
secure  real  progress  by  positive  action.  Avoid  futile 
experimental  changes,  which  cause  irritation  to  passen- 
gers. 

One  of  the  most  attractive  means  of  reducing 
over-congestion  is  what  may  be  called  staggering  the 
hours  of  opening  and  closing  stores  and  offices  in  order 
better  to  distribute  the  traffic.  The  advantage  to  the 
car  rider  is  obvious,  but  the  difficulty  of  securing  co- 
ordinated action  by  the  various  interests  involved  has 
prevented  a  very  general  use  of  this  plan.  Every  effort 
should  be  made  to  reduce  the  peak  demand  for  serv- 
ice and  to  spread  the  traffic  over  the  off-peak  periods 
when  a  large  part  of  the  system  capacity  is  idle.  These 
results  might  be  secured  by  making  the  service  more 
attractive  through  reductions  in  fare,  extension  of 
routes  or  otherwise  during  off-peak  hours. 

The  fare  collection  system  may  be  adapted  to  con- 
ditions so  as  greatly  to  relieve  congestion.  The  pay- 
leave  outbound  and  pay-enter  inbound  system  on  cars 
which  are  looped  back  at  the  central  district  appears  to 
be  an  important  help  in  getting  cars  over  the  road 
promptly.  This  method  has  been  abandoned  in  some 
instances  for  special  reasons.  The  system  which  re- 
quires the  passenger  to  pay  his  fare  as  he  passes  the 
conductor  who  is  stationed  near  the  center  of  the  car 
has  many  advocates;  for  through  operation  and  in 
cases  of  crowds  at  locations  out  of  the  ordinary  every- 
day experience,  it  yields  better  results. 

Card  passes  which  entitle  the  holder  to  an  un- 
limited number  of  rides  help  to  facihtate  fare  collec- 
tion, as  does  the  liberal  use  of  tickets  or  tokens.  This 
liberal  use  of  tickets  is  augmented  by  a  considerable 
difference  between  the  cash  fare  required  and  the  price 
of  the  ticket.  Street  men  to  assist  in  collecting  pre- 
paid fares  and  others  to  facilitate  the  loading  of  cars 
at  heavy  traffic  points  help  to  accelerate  traffic. 

The  size  of  cars  which  is  limited  in  some  cities 
has  a  serious  effect  upon  congestion.  Broad  streets 
permit  large  cars  with  liberal  entrances  and  exits. 
Narrow  streets  require  small  cars  and  limited  openings, 
which  increase  the  time  of  loading  and  unloading,  and 
decrease  the  ability  to  move  passengers  promptly, 
thereby  increasing  street  congestion. 

The  low-floor  car  has  been  of  undoubted  benefit  in 
accelerating  traffic.  Cross  seats,  hand-holds  and  rail- 
ings work  both  ways ;  in  light  traffic  they  help  passen- 
gers to  move  promptly,  but  when  the  car  is  crowded, 
act  as  obstructions  and  retard  the  flow  of  passengers 
in  and  out  of  the  car.  Cross  seats,  however,  are  de- 
manded by  car  riders,  and  must  be  supplied. 

The  use  of  the  same  route  in  the  congested  district 
by  cars  serving  the  same  general  outlying  section  not 
only  provides  more  regular  and  frequent  service  for 
some  patrons,  but,  through  a  more  even  distribution  of 
traffic,  reduces  unit  overloading  and  consequent  delays. 

Loading  facilities,  such  as  loading  platforms  and 


October,  1921 


THE   ELECTRIC  JOURNAL 


461 


safety  zones  which  permit  passengers  to  board  and 
leave  cars  promptly  in  safety  and  eliminate  the  neces- 
sity for  damming  up  vehicular  traffic  to  the  rear  of  the 
car,  have  produced  good  results. 

The  location  of  stopping  points  for  cars  justifies 
the  most  careful  consideration.  Too  many  stops 
means  trouble  in  adherence  to  schedules.  The  running 
time  allowed  is  either  too  little  when  all  stops  or  too 
liberal  when  few  stops  are  made,  causing  bunching  of 
cars  in  the  former  and  dragging  in  the  latter  case ;  both 
of  which  cause  congestion.  The  location  of  stops 
with  reference  to  their  influence  on  traffic  in  general 
has  an  important  bearing.  For  example;  at  branch- 
ofifs,  branch  line  cars  should  stop  for  passengers  on 
the  branch  and  not  on  the  main  line.  In  the  same  way, 
stops  can  be  changed  so  as  to  relieve  vehicular  traffic  by 
locating  stops  beyond  the  path  of  heavy  diverging 
traffic.  In  practice,  stops  in  the  middle  of  blocks  leav- 
ing cars  free  to  proceed  at  the  intersections,  have  given 
good  results.  Ovei'-concentration  of  loading  and  un- 
attractive service  through  long  distances  between  stops 
should  be  avoided. 

One  matter  which  does  not  seem  to  have  received 
the  consideration  it  deserves  is  the  exact  designation 
of  stopping  points  and  the  positive  stopping  of  cars  at 
those  points,  in  order  that  passengers  may  not  lose  time 
walking  from  a  stop  sign  to  the  actual  stopping  point. 
Dififerent  types  of  cars  with  entrances  located  at  dif- 
ferent places  should  be  avoided,  because  they  tend  to 
confuse  passengers  and  add  to  delays. 

Multiple  berthing  is  of  considerable  assistance  in 
expediting  traffic,  particularly  with  street  men  in  at- 
tendance. The  full  value  of  this  system  is  shown  in 
some  surface  car  subway  stations,  where  the  route  of 
each  car  and  its  berth  location  are  shown  before  ar- 
rival, on  an  indicator  visible  from  all  parts  of  the  sta- 
tion. 

Types  of  cars  present  interesting  possibilities. 
Over-congestion  is  directly  aftected  by  the  amount  of 
street  area  occupied  by  transportation  facilities.  Other 
things  being  equal,  congestion  can  be  minimized  by 
using  a  car  which  occupies  the  least  amount  of  street 
area  for  the  number  of  passengers  carried.  The  ques- 
tion of  double-deck  cars  naturally  presents  itself. 
Here  is  a  unit  which  occupies  the  same  street  area  and 
will  seat  twice  as  many  passengers  as  the  single-deck 
car.  During  rush  hours,  as  a  transportation  unit,  it 
may  not  be  considered  as  having  double  the  capacity  of  • 
a  single-deck  car,  but  it  does  have  a  substantiallv 
greater  capacity  than  the  single-deck  unit.  The  in- 
creased track  capacity  and  street  relief  in  the  congested 
district,  and  economy  in  man  power,  offers  attractive 
rewards  for  the  development  of  a  double-deck  car 
which  can  load,  unload,  accelerate  and  generally  main- 
tain schedules  as  well  as  the  single-deck  car  with  a  rea- 
sonable degree  of  safety  and  comfort  for  passengers. 
Physical  limitations,  such  as  low  bridges  do  not  seem 
to    oflfer    insurmountable    obstacles    to    their    use,    al- 


though there  are  other  considerations  which  would 
seem  to  limit  their  field  of  operation  to  heavy  traffic 
Imes.  Numerous  unsuccessful  attempts  to  apply  in 
practice  the  theory  underlying  the  use  of  this  type  of 
equipment  should  not  discourage  careful  consideration 
of  its  adaptability. 

Consideration  of  the  size  of  transportation  units 
brings  up  the  question  of  train  operation.  Two  or 
three  cars  operating  independently  generally  cause 
more  congestion  than  if  coupled  in  a  train.  Special 
conditions,  such  as  short  blocks  causing  frequent  over- 
laps of  trains  on  cross  streets  in  the  congested  district, 
would  make  train  operation  inadvisable.  Aside  from 
special  conditions,  however,  increased  train  operation 
will  reduce  congestion,  and  where  traffic  and  other 
conditions  justif}-,  trains  should  be  used.  Train  opera- 
tion brings  up  the  question  of  dead  trailer  versus  mul- 
tiple unit  operation.  Maintenance  of  better  schedules 
.'•nd  comfort  of  rear  car  passengers,  especially  on  hill 
l:nes,  would  seem  to  indicate  the  desirability  of  mul- 
tiple unit  operation,  in  spite  of  the  increased  cost  of 
investment,  power  and  maintenance.  One  railway 
company  is  experimenting  with  two  cars  having  a  com- 
municating passage  way  connected  over  an  intermedi- 
ate truck,  the  whole  unit  carried  on  three  trucks,  giving 
?  passenger  capacity  of  nearly  double  one  car  with  a 
greatly  increased  labor  economy,  two  men  operating 
the  entire  unit.  Its  large  overhang,  however,  would 
prevent  its  use  on  curves  in  narrow  streets. 

In  some  instances,  the  use  of  multiple-unit  equip- 
ment has  been  avoided  by  installing  two  motors  on  each 
cf  two  cars  of  a  permanent  train.  In  this  way  the  ad- 
vantage of  power  on  each  car  is  gained  without  the  dis- 
advantage of  the  increased  cost  of  multiple  unit  equip- 
ment. 

Left  hand  turns  of  all  vehicles — particularly  street 
cars — should  be  avoided,  especially  in  double  traffic  di- 
rection congested  streets.  Where  lines  are  looped  back 
in  congested  areas,  this  means  a  left  hand  curve  and 
crossing  of  all  cars  at  the  initial  point  of  the  loop,  but 
when  this  crossing  can  be  made  at  a  less  congested 
point,  it  will  be  justified  by  the  elimination  of  three 
left  hand  turns  in  the  more  congested  locations. 

Special  attention  should  be  paid  to  delayed  and 
bunched  cars  about  to  enter  the  congested  area.  When 
cars  are  bunched  by  a  delay  on  outlying  lines,  their 
operation  together  through  the  congested  area  will  im- 
pair rather  than  improve  the  service.  Grade  crossings 
of  steam  railroads  are  a  prolific  source  of  this  cause  of 
congestion.  Facilities  for  turning  some  of  the  bunched 
cars  short  should  be  made  and  used  promptly  when 
needed. 

A  car  fender  projecting  four  feet  beyond  the  end 
of  car  will  reduce  track  capacity  on  straight  track  about 
ten  percent  which  is  increased  by  the  interference  be- 
tween projecting  fenders  and  other  vehicular  traffic 
near  curves.  At  least  ten  rush  hour  passengers  out  of 
every  hundred  have  to  hang  to  straps  because  of  such 
fenders. 


462 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


Large  interurban  cars  geared  to  high  speed,  with 
long  stairway  entrances  difficult  to  board  and  leave,  and 
entirely  unsuited  to  operation  through  congested  streets 
with  frequent  stops,  should  be  eliminated. 

Track  and  overhead  facilities,  particularly 
switches,  should  be  kept  in  the  best  condition  to  pre- 
vent failures  and  delays. 

The  street  parade  has  always  been  the  bugaboo  of 
the  street  railway  man;  not  so  much  on  account  of  the 
trouble  it  makes  for  him,  but  because  of  the  senseless 
manner  in  which  it  is  frequently  allowed  to  interfere 
unnecessarily  with  the  comfort,  business  and  conveni- 
ence of  thousands  of  people.  Parades  cannot  be  elimin- 
ated, but  they  should  be  routed  so  as  to  produce  the  de- 
sired results  with  a  minimum  of  interference. 

Well  equipped  trouble  wagons  centrally  located 
with  proper  signal  or  telephone  facilities,  should  re- 
spond promptly  to  calls  for  help.  Every  large  property 


should  have  hose  jumpers  for  relief  from  blockades  by 
fire  hose. 

Finally  and  most  important  is  the  spirit  of  "let's 
go"  in  the  operating  personnel.  To  the  extent  that  em- 
ploj'es  can  be  interested  in  trying  to  put  cars  over  the 
road,  to  that  extent  will  it  be  possible  to  take  advantage 
of  every  opportunity  to  reduce  congestion.  Without 
their  interest,  nothing  worth  while  can  be  done.  With 
their  interest,  anything  within  reason  can  be  done. 

Co-operation  by  the  company  and  its  employes 
with  those  charged  with  the  enforcement  of  traffic 
regulation  should  be  established. 

Correct  measurements,  calculations  and  conclu- 
sions regarding  the  physical  problems  involved  are  es- 
sential but  easy  as  compared  to  the  real  job  of  dealing 
with  the  human  element  in  such  a  way  as  to  make  the 
physical  property  valuable  to  the  car  rider  and  the 
company  and,  therefore,  to  the  community. 


IJsD  ■\\v\  Aoii^f)  of  Elociric  ^iXoxops 


J.  M.  mil  1 1 

Manager,  Motor  Eiii;i       :     ,.   I  '■  pt., 
Westinghouse  Electric  &  Mfg.  Company 


IN  THE  USE  of  electric  motors,  it  is  difficult  to 
establish  the  point  at  which  abuse  starts.  All  rail- 
way operating  men  recognize  the  necessity  for  a 
certain  amount  of  maintenance  work  on  railway 
motors,  but  it  is  sometimes  difficult  to  establish  the  line 
at  which  maintenance  expense  passes  normal  and  be- 
comes excessive.  The  dividing  line  between  proper 
maintenance  expense  and  undue  trouble  is  constantly 
shifting.  It  shifts  due  to  changing  operating  condi- 
tions; service  that  today  seems  abnormal,  tomorrow 
becomes  normal.  It  shifts  due  to  improvements  in  de- 
sign and  construction ;  motors  that  have  certain  limi- 
tations today  are  tomorrow  replaced  by  motors  having 
those  limitations  removed  or  at  least  raised.  The  lasT 
few  years  have  demonstrated  clearly  what  a  large  effect 
the  character  of  the  available  labor  supply  has  on  main- 
tenance. The  conscientious  and  intelligent  workman 
not  only  does  a  given  overhaul  job  more  economically, 
but  he  does  it  better.  A  repair  job,  poorly  done,  often 
starts  a  series  of  other  troubles.  In  view  of  all  of  the 
variable  elements  involved  it  is  impossible  to  set  up  the 
same  standards  of  inspection  and  maintenance  on  all 
properties.  Each  group  of  operating  men  must  analyze 
the  local  service  requirements  and  arrange  to  give  the 
particular  equipment  that  is  in  use  an  amount  of  in- 
spection and  care  that  will  result  in  maximum  service 
and  minimum  maintenance  expense  in  the  long  run. 
Recognizing  the  severe  operating  conditions  and 
the  difficulty  operating  managers  have  in  securing  high- 
^rade  workmen,  the  development  of  the  railway  motor 


The  entire  electrical  equipment  of  an  electric  rail- 
way car  differs  from  the  other  equipment  entering  into 
the  construction  of  the  car,  in  that  its  successful  op- 
eration is  dependent  on  the  integrity  of  the  current  car- 
rying parts,  the  failure  of  anyone  of  which  causes  de- 
lay and  expense.  These  parts  are  composed  of  ma- 
terial that  must  be  selected,  not  primarily  for  their 
strength,  but  for  other  characteristics,  as  shown  in 
Table  I.  This  clearly  indicates  why  motors  require 
reasonable  care  both  in  their  application  and  use. 

Abuse  is  quickly  reflected  in  high  maintenance. 
It  may  exist  either  in  the  application  of  the  equipment 
or  its  operation.  An  example  of  the  former  is  the  case 
where  the  leads  froin  the  car  body  to  the  motor  are  in- 
adequately supported,  so  that  they  are  allowed  to  have 
too  much  movement  and  come  in  contact  with  parts  of 
the  truck  or  motor  frame.  An  example  of  the  latter 
is  permitting  excessive  wear  to  take  place  in  the  bear- 
ings before  replacement,  thereby  subjecting  the  motor 
to  excessive  vibration. 

The  one  overshadowing  cause  of  trouble  in  rail- 
way motors  is  vibration.  This  vibration  originates 
from  track  conditions,  gear  tooth  impact  and  frequent 
•starting  and  stopping,  and  is  greatly  increased  by 
excessive  clearance  in  bearings.  Cases  have  been  ob- 
served where  clearances  as  large  as  5/16  inch  have 
been  permitted  in  axle  bearings  before  replacement. 
Under  such  conditions  the  motor  is  constantly  being 
subjected  to  a  series  of  blows  that  must  result  in 
trouble.     Axle  bearing  clearances  so  large  as  this  are 


has  been  along  the  lines  of  producing  a  sturdy  motor,  perhaps  not  common,  but  serious  punishment  of  the 
It  must  be  recognized,  however,  that  an  electric  motor  motor  starts  long  before  the  clearance  has  reached  such 
is  fundamentally  a  structure  that  requires  intelligent  r.  value.  Systematic  inspection  that  will  bring  all  bear- 
attention,  ings  up  for  attention,  when  they  have  reached  certam 


October,  1921 


THE   ELECTRIC  JOURNAL 


463 


maximum    clearance,    will   pay   large    dividends    in  re- 
duced motor  trouble. 

The  railway  motor  has  been  very  highly  developed 
to  meet  operating  conditions  and  it  will  stand  as  much 
vibration  as  any  type  of  motor  built,  but  it  can  be  and 
is  abused  in  service.  Some  comparison  with  motors 
for  industrial  purposes  may  be  of  interest.  In  motors 
of  sizes  comparable  with  railway  motors,  there  are  two 
general  classes  of  direct-current  industrial  motors. 
These  are  the  so-called  general  purpose  motors  that 
drive  line  shafts,  machine  tools,  pumps,  etc.,  and  the 
mill  type  motors  used  for  driving  auxiliaries  and  cranes 
in  steel  mills. 

TABLE  I— THE  ELEMENTS  OF  THE  ELECTRICAL 
CIRCUIT    IN    A   MOTOR 


Part 

^lJ■„^.=^,1  n^^A      I'Characteristics  Governing 
Material  Used     ^^^^-^^  ^^  U;,i^r\^\ 

Motor  leads 

Dielectric  strength 
Flexibility 
Insulation              lAbility  to  resist  chafing 
[Ability  to  resist  effect  of 
\vater,  mud  etc. 

Conductivity 
Stranded  copper  and  thermal  capacity 
Flexibility 

Brush  holders 

Jnsulation 

Dielectric  strength 
.\bility  to  withstand  vibration 
.Ability  to  withstand  flashing 
.Ability  to  withstand  heat 

Carbon  box 
brass 

Carbons 

.Vbility  to  resist  corrosion 

Ability  to  withstand  vibration 

Conductivity 

and  thermal  capacity 

Resistance 

Scouring  effect 

Ability  to  withstand  vibration 

and  blows 

Ability  to  stand  overloads 

Commutator 
bars  and 
insulation 

Copper 

Conductivity 

Ability  to  resist  stress  due  to 

high  speed 

Ability  to  resist  blistering  on 

surface 

Mica 

Dielectric  strength 
Ability  to  withstand  heat 

Armature 

coils 
Field  coils 

Insulation 

Dielectric  strength 
.\bility  to  withstand  heat 
Ability  to  withstand  moisture 
Ability  to  withstand  vibration 

Copper  wire 
or  ribbon 

Conductivity 

Abilitv  to  withstand  vibration 

The  general  purpose  motor  is  suitable  for  either 
belted  or  geared  service  and  is  capable  of  standing  up 
under  the  ordinary  vibration  incident  to  only  moder- 
ately secure  foundations,  gears  aligned  only  moder- 
ately well  and  vibration  transmitted  from  the  driven 
machine.  The  construction  of  these  motors  is  lighter 
than  that  of  the  railway  motor.  Attempts  to  use  these 
motors  or  some  of  their  parts,  such  as  brushholders,  in 
railway  service  have  always  failed,  although  in  the  serv- 
vice  for  which  they  are  designed  they  give  a  length  of 
life  in  excess  of  that  of  railway  motors. 

The  same  motors  gave  considerable  trouble  when 
used  in  steel  mills,  on  reversing  tables  for  instance,  and 
this   led   to    the   development   of    the   mill-type   motor. 


These  motors  resemble  railway  motors,  but  have  even 
heavier  mechanical  parts  because  of  the  rough  service 
and  the  great  expense  incident  to  any  interruption  in 
service.  These  motors  are  regularly  plugged,  often 
several  times  a  minute,  and  frequently  operate  with 
gearing  in  poor  alignment  or  with  broken  teeth.  Even 
these  severe  operating  conditions  however  fail  to  pun- 
ish the  motors  as  severely  as  does  railway  service  and, 
as  a  result  the  maintenance  is  lower.  The  principal 
reason  for  this  is  that  the  motors  are  not  hauled  about 
over  tracks,  with  the  attendant  rail  end  blows,  cross- 
over jolts  and  stretches  of  bad  track.  Poor  track 
maintenance  is  undoubtedly  reflected  promptly  in  high 
motor  maintenance  and  is  one  of  the  worst  forms  of 
of  motor  abuse. 

Assuming  that  all  the  mechanical  conditions — 
track,  gears  and  bearing  clearances — are  good,  there  is 
still  the  possibility  of  seriously  damaging  the  motor 
windings  by  improper  overloads.  There  is  no  great 
difficulty  involved  in  selecting  the  correct  size  of  mo- 
tors for  application  on  cars  of  a  given  weight  to  oper- 
ate under  stated  conditions  of  schedule  speed,  grades 
and  loads.  When,  however,  such  cars  are  used  to  push 
disabled  cars  up  long  grades  or  to  clear  from  the  track 
heavy  snow  that  should  be  removed  by  sweepers  or 
plows,  the  loads  on  the  motors  may  easily  be  such  as 
to  roast  the  windings  seriously.  This  condition  is  par- 
ticularly true  of  the  light  weight  safety  cars,  which  are 
sometimes  employed  to  push  in  disabled  heavy  cars  or 
in  snow  bucking.  The  motors  on  these  cars  necessarily 
have  low  thermal  capacity.  On  short  time  heavy  over- 
loads in  excess  of  the  rating  the  temperature,  there- 
fore, rises  rapidly.  A  somewhat  higher  short  time  load 
can  be  carried  if  the  motors  are  cold  at  the  start  than  if 
they  are  at  their  normal  operating  temperature,  but  the 
following  figures  showing  the  internal  temperatures, 
i.e.,  at  the  copper,  inside  the  insulation,  indicate  that, 
with  heavy  overloads  the  temperature  can  quickly  be 
brought  from  cold  to  an  injurious  value.  In  these 
tests  the  motor  started  cold  in  each  case. 

Motor  rated-37  amps.,  600  volts,  60  min.,  75°  C  rise 
Motor  tested-63  amps,  450  volts,  20  min.,  150°  C  rise 
Motor  tested-ioo  amps,  450  volts,  5  min.,  175°  C  rise 

Motors  having  greater  short-time  overload  ca- 
pacity can  easily  be  applied  to  these  cars  but  they  will 
weigh  and  cost  more.  The  use  of  the  lighter  motor  is 
good  engineering,  and  the  benefit  accrues  to  the  user, 
but  it  must  be  matched  by  intelligent  operation. 

Too  strong  emphasis  cannot  be  placed  on  the  wis- 
dom of  a  policy  of  maintenance  that  continually 
analyzes  the  conditions,  both  mechanical  and  electrical, 
that  the  motors  are  being  required  to  fulfill.  Such 
analysis  leads  to  a  clear  knowledge  of  the  conditions 
under  which  it  is  more  econnomical  to  spend  money 
for  in.spection  and  attention,  than  through  inattention 
to  allow  the  equipment  to  be  punished  to  the  extent 
that  much  more  money  must  be  spent  for  overhauling. 


H.  A.  LEONHAUSER 

Asst.   Supt.   Rolling   Stock  and  Shops, 
The  United  Railw'^ys  &  Electric  Company  of  Baltimore 


ADEQUATE  maintenance  of  electric  railway 
equipment  means  much  to  the  operating  com- 
pany, both  from  the  standpoint  of  reduced  costs 
and  also  from  the  standpoint  of  improved  service. 
Among  the  principal  items  for  consideration  in  plan- 
ning an  ideal  main  repair  shop  are  a  suitable  location 
and  buildings  especially  adapted  to  the  work. 

The  site  should  be  centrally  located,  and  close  to 
both  rail  and  water  facilities,  with  the  idea  of  bringing 
all  the  principal  work  to  the  shop  and  using  the  car 
houses  or  depots  for  inspection  and  light  repairs  onlv. 
Steam  road  connections  should  be  brought  both  into 
the  storage  yard  and  the 
shops  proper,  so  that  all 
freight,  new  ecjuipment,  etc., 
can  be  unloaded  or  reloaded 
with  the  minimum  amount  of 
handling. 

The  buildings    should  be 
built   of   reinforced   concrete, 
or  brick  and  stone  with  slate 
or  tile  roof.    They  should  be 
of    the    sawtooth    type,    high 
enough  to  permit  the  hoisting 
of     car      bodies      from      the 
trucks  by  the  use  of  electric 
traveling  cranes.     It  is  high- 
ly essential    that    shops    have 
ample    light    and    ventilation, 
not  onh-  to  make  them  bright 
cheerful  and  comfortable  for 
the     workmen,     but    also     to 
speed    up    the     work.      They 
should    have    open    pit     con- 
struction of    reinforced    con- 
crete.    The  floors  should  be  of  concrete,  except  in  the 
motor  and  truck  repair  department  where  they  should 
be  of  treated  wood  block.    The  spacing  between  tracks 
should  be  not  less  than  5  ft.  4  in.     The  buildings  shouUl 
be  fire  proof,   and   so   constructed   that  their  mainten- 
ance will  be  reduced  to  the  minimum.     They  should 
include  the  necessar}-  and    proper    facilities    and    con- 
veniences such  as  lavatoiy  with  shower,  metal  lockers, 
etc.,   in  order  to  make  the  surroundings  as  agreeable 
and  pleasant  for  the  employes  as  possible.     Special  at- 
tention should  be  given  to  the  installation  of  both  the 
heating    and    lighting   systems.     Finally    the    buildings 
should  be  ecjuipped  with  automatic  sprinklers,  backed 
by  a  liberal  and  high  pressure  city  water  supply,  also 
stand  pipes  with  linen  hoses  and  pails,  and  a  system 


of  auxiliary  automatic  fire  alarms  and  watchman's  sig- 
nals. The  sub-storeroom  and  tool  room  should  be  cen- 
trally located,  so  as  to  make  it  convenient  for  the 
workmen  which  again  means  efficiency  and  economy. 

Special  consideration  .should  be  given  to  the  group- 
ing of  the  buildings,  as  by  this  means  only  can  we  pro- 
duce the  greatest  economy  and  efficiency.  In  the  cen- 
ter of  Fig.  I  we  have  the  electric  and  oxy-acetjdene 
welding  department,  next  the  blacksmith  shop,  the 
wheel  borer,  press  and  wheel  lathe,  the  register  room, 
tool  roorn,  sub-storeroom,  machine  shop  including  bab-j 
bitting  outfit,  then  the  electrical  department  where  all 


I — LAYOUT  OF  AN  IDEAL  MAIN  REPAIR  SHOP 

armature  and  field  winding,  coil  winding,  controller  and 
other  electrical  repairs  are  made.  The  electrical  de- 
partment should  have  a  very  large  oven  used  for  the 
baking  and  dr}ang.  Adjoining  this  department  is  the 
motor  and  truck  shop,  commonly  called  the  over-haul- 
ing shop,  where  all  the  wheeling,  truck,  brake  and  gen- 
eral overhauling  of  the  entire  equipment  is  done. 

With  this  lay-out  the  machine,  blacksmith  shop, 
and  armature  department  and  sub-storeroom  are  lo- 
cated so  as  to  make  it  convenient  to  make  repairs  to 
any  part  of  the  car,  thus  reducing  the  time  element 
in  the  handling  of  material  to  the  minimum.  The 
paint  shop  should  be  equipped  with  racks  for  the  hand- 
ling of  sash,  doors,  etc.,  scrubbing  machine,  adjusta- 
ble painting  scaffolds,  washing  trays,  etc.     Special  at- 


October,   1921 


THE  ELECTRIC  JOURNAL 


465 


tention  should  be  given  to  the  proper  lighting,  heatinij 
and  ventilation  so  as  to  assist  the  drying  of  the  paints 
and  varnish.  Adjacent  to  the  paint  shop  is  the  main 
storeroom  with  adequate  facilities  for  the  efficient 
handling  of  the  many  items  daily  required  for  the  en- 
tire property.  Two  bays  adjoining  the  paint  shop  arc 
provided  for  storing  open  cars  and  cars  requiring  gen4 
eral  overhauling.  The  oil  and  paint  storage  building, 
should  be  fire  proof  and  equipped  with  modern  recep- 
tacles and  pumps  for  handling  all  lubricants,  and 
paints.  The  track  for  the  steam  road  should  connect 
with  a  platform  scale  of  200,000  lbs.  capacity,  and  a 
hoist  for  unloading  new  cars  and  heavy  material. 

MAINTENANCE   AIMS 

Fundamentally,  maintenance  begins  with  the  type 
of  car,  schedule  speeds,  grade  conditions,  etc.  These 
havmg  been  carefully  considered,  it  is  then  the  duty 
of  the  Superintendent  of  Equipment  to  obtain  the  max- 
imum results  for  the  minimum  outlay.  High  grade 
materials  and  careful  workmanship  should  be  used  in 
all  parts  of  the  equipment,  bearing  in  mind  that  simpli- 
city and  durability  are  two  great  factors  in  reducing 
costs.  By  using  high  grade  materials,  we  not  onlv 
keep  down  the  weight  of  the  car  but  prolong  the  first 
repair  period  as  well.  For  instance,  a  manganese 
brake  shoe  head  will  last  at  least  four  times  as  long 
as  a  malleable  iron  head.  Case  hardened  pins  and  busii- 
ings,  babbitt  lined  journal  bearings,  manganese  bronze 
check  plates,  etc.,  all  give  much  longer  life,  fullv  justi- 
fying their  extra  cost. 

We  should  also  consider  the  inter-changeability  <,{ 
parts,  the  use  of  jigs  for  drilling,  effective  blow-out 
coils  in  the  control  removable  finger  tips,  high  grade 
babbitt  in  all  motor  bearings,  the  under-cutting  of  all 
commutators,  the  use  of  high  grade  carbon  brushes, 
all  of  which  help  to  increase  the  first  life  and  conse- 
quently aid  in  the  reduction  of  maintenance  costs.  An- 
other and  very  important  item  is  standardization,  not 
only  from  the  standpoint  of  the  mechanical  department, 
but  of  the  supply  department  as  well.  Therefore,  glass 
of  all  kinds  .should  be  kept  to  size  and  thickness,  brake 
shoes,  brake  shoe  heads,  wheels,  resistance  grids,  gears 
and  pinions,  etc.,  should  be  standard.  If  the  angle  of 
helical  gears  and  pinions  is  standardized,  the  mainten- 
ance costs  of  the  mechanical  department  will  be  re- 
duced as  the  number  of  spare  parts  necessary  to  be  . 
earned  by  the  supply  department,  which  consequently 
reduces  the  amount  of  capital  invested  in  idle  stock. 

Considerable  money  is  wasted  by  allowing  parts 
to  wear  down  too  far.  If,  for  instance,  the  brak-e 
shoes  are  allowed  to  run  too  long,  cutting  out  of  the 
brake  shoe  head,  and  excessive  flange  wear  of  the 
steel  wheels  will  result.  Thus,  thousands  of  miles  are 
turned  off  the  wheel  tread  to  build  up  the  flange  to  the 
proper  size  and  shape.  The  latter  is  an  exceptionallv 
heavy  item  and  should  be  watched  very  carefully. 
V\'orn  brake  le\er  pins  and  bushings  should  be  renewed 


m  order  to  protect  tiie  Ie\'ers.  .-\llowing  armature 
bearings  to  run  too  long  not  giving  the  waste  and  oiling 
the  profier  attention,  failure  to  watch  the  condition  of 
the  dowels  or  keys,  and  the  condition  of  the  outside 
diameter  of  the  bearing  and  the  diameter  of  the  bear- 
ing cap  or  housing,  will  result  in  the  stripping  of  arma- 
tures and  fields,  which  is  another  heavy  item  of  ex- 
pense. Cast  iron  wheels  should  be  frequently  in- 
spected for  badly  chipped  flanges,  heavy  flanges, 
cracked  spokes  and  treads,  and  bad  flat  spots. 

The  careless  handling  of  armatures  by  supply  car 
crews,  and  the  workmen,  such  as  rolling  theiti  over 
rough  floors,  nail  heads,  and  other  foreign  particles  may 
cause  many  failures. 

POWER    RECORDERS 

The  installation  of  power  recorders,  with  the  con- 
stant co-operation  of  the  Transportation  Department, 
will  result  in  great  reduction  of  maintenance  costs. 
The  power  recorders  in  many  cases  were  installed  prin- 
cipally to  eftect  a  saving  in  poweir,  but  several  years  of 
service  has  proven  that  due  to  coasting,  the  motors  are 
running  much  cofiler,  and  the  life  of  both  armature 
and  fields  are  prolonged  considerably.  The  life  of  the 
controller  fingers  and  burning  tips  are  also  increased, 
there  is  also  much  less  braking  which  results  in  tlie 
greater  life  of  the  brake  shoes  and  wheels,  and  inci- 
dentally a  great  falling  oft'  in  cases  of  accident  damage 
has  resulted. 

CONTACTORS 

The  use  of  auxiliary  contacts  in  place  of  circuit 
breakers  has  almost  entirely  eliminated  controller  ex- 
plosions, removing  at  the  same  time  the  controller 
flashing  from  the  platforms  of  the  car.  The  life  of  the 
burning  tips  and  fingers  is  considerably  increased.  An- 
other important  feature  of  the  contactor,  when  trailers 
are  used,  is  the  automatic  setting  of  the  overload  trip. 
When  the  disconnecting  switch  is  tlirown  the  air  cocks 
open  and  the  overload  trip  is  changed  to  the  high  set- 
ting. When  the  trailer  is  uncoupled  the  disconnecting 
switch  is  thrown,  closing  the  air  cocks  and  the  over- 
load trip  is  changed  to  the  low  setting. 

MULTIPLE   UNIT  OPERATION 

Cars  equipped  with  semi-automatic  control  wi<h 
straight  air  brakes  having  emergency  feature,  have 
been  operating  successfully  for  several  \ears.  The 
improvements  in  the  design  of  the  switch  in  the  group 
have  lowered  the  maintenance  decidedly :  the  burning 
tips  of  the  older  switch  had  to  be  replaced  about  everv 
6000  miles  in  severe  service,  while  the  tips  on  the  im- 
proved switch  need  no  replacing  under  30  000  miles  in 
the  same  service. 

This  type  of  control  can  also  be  arranged,  by  add- 
ing an  additional  overload  trip,  to  meet  the  require- 
ments of  trailer  service,  so  that  when  the  disconnecting 
switch  is  thrown,  the  range  of  the  overload  trip  is 
increased  to  take  care  of  the  additional  load.     When 


466 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


the  trailer  is  uncoupled  and  the  disconnecting  switch 
is  thrown  in  the  opposite  direction,  the  range  of  the 
overload  trip  is  decreased  for  a  single  car  operation. 

TOOLS 

The  tools  and  equipment  required  for  handling 
looo  to  I200  four  motor  equipments  are  listed  in  Table 
I.  Individual  motor  drive  should  be  installed  where 
possible  to  eliminate  all  shafting  and  belts. 

TABLE  I-TOOLS   AND    EQUIPMENT    FOR    VARIOUS    DEPART 
MENTS  OF  REPAIR  SHOP 


MACHINE    SHOP 
1 — 25    in.    heavy    duty    engine 

lathe 
2 — 20   in.  lathes,   eame  type  of 

control 
2 — 16    in.    engine    lathes,    same 

type  control 
1 — Speed    lathe    o£    any    stand- 
ard type 
1 — Standard   turrett  lathe  with 

geared  head  No.  4 
2 — Upright  drill  presses  25  in. 

swing 
1 — Single       spindle       sensitive 

drill    press 
1 — No.  3  plain  milling  machine 

with  dividing  head   and  vise 

complete 
1 — Standard     improved      4      ft. 

planer  with   8ft.   table 
1 — Shaper   16   in.   stroke 
1 — Standard    drill    grinder 
1 — Floor      grinder      to      carry 

grinding   wheels  size   16   in. 

by    1.5    in. 
-Floor       grinder      to      carry 


wheels    12 
1.25 


by    1 


by 


1 — ^Pinion  puller 

1 — Standard  cutter  and  reamer 

grinding   machine 
1 — Standard    boring    mill    with 

five     point     chuck     anl     4ft. 

table 
1 — Standard  wheel  lathe 
1 — 300  or  500  ton  wheel  press 
1 — Standard    double    head    bolt 

cutter  2.5    in. 
1 — Cold    cutting    saw 
1 — Standard      36      in.      engine 

lathe,    triple   gear 
1 — Up-to-date     babbitting     out- 


foot 


com- 


of    pneuma- 


fit 

1 — 500      cubic 
pressor 
Standard     1 
tics 
BLACKSMITH   SHOP 

1 — Furnace    . 

4 — Forges 

1 — Gas    furnace    for    tempering 
high   speed   steel 

1 — Tank    for    oil    quenching    of 
springs,    etc. 

1 — Mohr   kerosine   torch 

1 — Heavy        pneumatic        drop 
hammer. 

1 — Punch    and    shear 

1 — Shop     built     crane     for   the 
handling    of   heavy    forgings 

1 — Roads   bender 

1 — Oxy-acetyline    welding    out- 
fit 

1 — Electric    welding    outfit 
PAINT    SHOP 

1 — Paint  mixing  machine 

1 — Sand  blast 

1 — Cane     seat     scrubbing     ma- 
chine 

2 — Large    scrubbing    and    rins- 
ing  troughs 


CARPENTER  SHOP 
1 — Standard  cut-off  saw 
1 — Circular    saw    with    38    by 

S8.5   in.   table 
1 — 16    in.    jointer 
1 — Standard    variety    moulder 
1 — 30  in.  planer 
1 — 42    in   band   saw 
1 — Set      automatic      band      saw 

guides 
1— Jig   saw 
1 — Tenon    machine 
1 — Car    straightener 
1 — No.   1  mortising  machine 
1 — Wood    bender 
1 — Sewing   machine 
1 — Electric  riveter 
1 — Drill    press 
1 — Vertical   boring  machine 
1 — Emery    wheel 

>rOTOR    AND    TRUCK    SHOP 
2 — Traveling    cranes    with    run- 

4 — 8000  lb.  triplex  chain 
blocks 

4 — Armature  lifts  or  trucks 

1 — Car   wheel    grinder 

1 — -Portable  control  rack  for 
running  trucks  out  from 
car  by    its  own   power 

1 — Special  shop  built  wagon.  3 
ft.  wide,  10  ft. long,  for  re- 
moving compressors,  brake 
cylinders,   etc. 

2 — 3000  lb.  triplex  chain 
blocks 

ARMATURE    DEPART- 
MENT 
8 — Modern     armature     winding 

stands 
2 — Testing    transformer,    range 

750.       1000,      1500,       2000, 

2500   volts 
3 — .\rmature    yokes    for    locat- 
ing   short    circuits 
4 — Armature   coil    winding  ma- 
chines 
1 — Tappins   machine 
3 — Pneumatic    coil    presses 
1 — Small     armature     yoke     for 

testing      short      circuits      of 

compressor    armatures 
1 — Universal    car    tester,    type 

F-2 
1 — Century   field    tester 
1 — Century  fault  finder 
4 — Shop    i)uilt    resistance 

sets 
1 — Milli-voU        meter        double 

scale  0-150  and  0-1500 
1 — Large    oven    with    dripping 

pans 
2 — 7  in.  I-beam  runways  with 

carriages       and      pneumatic 

hoists 
1 — Undercutting      or      grooving 

machine    with    exhaust    fan 
3 — Gas     furnaces     for     heating 

soldering  irons,  etc. 


SPECIAL  TOOLS  AND  EQUIPMENT 

Many  hours  will  be  wasted  by  workmen  who  d) 
not  have  enough  or  the  proper  tools  for  handling  the 
work  economically,  therefore  the  foreman  in  charge 
should  -see  that  special  tools  are  kept  in  the  tool  room 
and  delivered  to  the  workmen  by  check.  The  special 
tools  are  to  be  provided  by  the  company.  "Special 
tools"  are  off-set  wrenches,  ratchet  wrenches,  ratchet 
screw  drivers,  off-set  socket  wrenches,  and  other  tools 


that  will  tend  toward  economy  and  efficiency.  Other 
special  tools  that  are  absolutely  essential  are  jigs  for 
brushholders  to  see  that  they  are  neutral,  straight  and 
true,  a  tool  for  the  machining  of  absolutely  equal  halves 
for  armature  and  axle  bearings,  the  straightening  up 
of  the  armature  air  ducts,  as  well  as  the  flaring  out  of 
the  armature  laminations  without  the  removal  of  la- 
minations. 

The  tanks  for  dipping  armatures  and  field  coils 
should  be  equipped  with  a  heating  coil  in  order  to  bring 
the  compound  up  to  the  proper  temperature  and  speci- 
fic gravity,  instead  of  using  benzine  or  gasoline.  The 
latter  really  destroys  the  body  of  the  compound,  while 
heating  softens  it  and  leaves  the  body  of  the  compound 
unimpaired.  The  best  results  can  be  obtained  by  first 
baking  or  heating  the  electrical  apparatus.  While  hot, 
place  it  in  the  heated  compound,  allowing  it  to  remain 
there  until  thoroughly  saturated,  when  it  should  be  re- 
moved, and  again  placed  in  the  oven  for  the  final  bak- 
ing. The  foregoing  treatment  is  especially  recom- 
mended when  armatures  are  in  for  minor  repairs  and 
have  seen  several  vears  of  service. 


If  a  motor  is  performing  satisfactorily,  it  should 
be  given  proper  and  careful  attention  at  proper  inter- 
vals, say  between  looo  and  1200  miles,  and  be  allowed 
to  run  until  the  bearings  have  worn  to  the  safety  point. 
It  should  then  be  removed  from  the  truck  and  put 
through  the  usual  cleaning  and  blowing  out  proce.ss. 
The  armature  and  field  coils  should  be  cleaned,  dipped 
and  baked.  The  shaft  and  commutator  should  be 
trued  up  and  the  mica  under  cut.  The  bearings  should 
be  rebabbitted  with  the  best  grade  of  babbitt  obtaina- 
ble. The  field  coils  should  be  tested  and  the  insulation 
and  strands  of  the  leads  put  in  good  condition.  I'he 
brush  holders  should  be  inspected  to  see  that  they  arc 
not  badly  worn,  that  the  springs  have  proper  tension, 
and  the  shunts  are  good  and  tight.  All  dowels,  dowel 
holes  or  keys  and  keyways  must  be  in  good  condition. 
If  the  bearings  are  pressed  in  the  housings,  see  that, 
they  are  put  in  with  proper  pressure,  and  the  waste 
properly  packed  and  lubricated. 

The  motor  should  then  be  reassembled  and  put 
back  in  serv'ice.  Experience  has  taught  us  that  the 
less  armatures  and  fields  are  handled,  the  fewer  will  he 
the  failures  and  delays,  and  the  greater  the  reduction 
in  maintenance  costs!  This  applies  to  the  equipment 
generally,  the  slogan  being  "up  to  the  safety  point," 
and  this  can  be  accomplished  by  good  and  careful  in- 
spection by  the  workmen  at  the  car  house,  followed  up 
by  the  car  house  foremen,  the  latter  being  checked  up 
at  proper  intervals  by  a  general  inspector  who  has  had 
several  years  of  experience  not  only  at  a  car  house,  but 
at  the  main  shop  as  well. 

LTjBRICATIDN 

Large  quantities  of  oil  and  grease  are  being 
wasted  daily  on  many  properties,  and  to  correct  this 


October,  1921 


THE   ELECTRIC  JOURNAL 


467 


we  should  work  with  the  engineers  of  the  oil  com- 
panies, in  order  to  follow  up  the  performance  of  the 
lubricants.  An  accurate  record  should  be  kept  of  all 
lubricants  delivered  and  used  during  the  month  at  each 
car  house.  Then  at  the  end  of  the  month,  the  mileage 
credited  to  each  car  house,  will  give  the  cost  of  lubri- 
cants per  1000  car  miles.  This  will  set  up  a  rivalry  be- 
tween the  various  car  house  foremen  and  no  doubt  will 
greatly  reduce  the  lubricating  costs. 

•).  WELDING  '.<.: 

Practically  all  railway  men  are  enthusiastic  in  both 
oxyacetylene  and  electric  welding,  both  of  which  mean 
much  to  street  railway  companies.  Some  of  the  weld- 
ing that  is  done  is  good,  but  some  is  not  what 
it  should  be.  After  all,  in  the  strict  sense  of 
the  word,  it  is  not  "welding,"  it  is  "fusing"  or 
"sticking"  and  it  is  an  acknowledged  fact  that  much 
depends  on  the  workman.  A  blacksmith  must  know- 
when  the  material  is  exactly  right  for  welding.  If  it 
ij  not  hot  enough  the  weld  cannot  be  made.  If  the  ma- 
terial is  too  hot,  the  material  is  "burnt"  and  although 
he  makes  a  weld,  the  joint  is  liable  to  fail  shortly  after 
being  put  in  service.  How  many  welders  today,  know 
whether  they  are  burning  the  material  and  whether  thev 
are  using  the  proper  material.  This  work  should  be 
done  by  a  reliable  blacksmith ;  a  man  who  displays  good 
judgement  and  who  is  willing  to  take  advice  from  i\ 
metallurgist  as  to  the  right  materials  to  be  used  for 
making  welds  on  all  classes  of  iron,  steel,  copper,  alum- 
inum or  brass. 

CAR    HOUSE    INSPECTION 

All  cars  should  be  given  a  brake  inspection  everv 
night.  A  standard  form  of  report  for  each  and  everv 
car  should  be  made  out  by  the  motorman  every  da}-,- 
checking  off  any  items  that  need  attention.  The  night 
workman  should  correct  the  defects  that  do  not  require 
much  time.  When  they  require  considerable  time  he 
should  place  a  shop  sign  under  lock  and  key  upon  the 
brake  handle,  holding  the  car  for  the  attention  of  the 
day  forces.  The  day  force  should  look  after  the  work 
left  over  by  the  night  man  or  men  (we  have  not  more 
than  two  night  men  at  any  car  house)  and  give  the 
cars  a  general  inspection.  The  cars  are  brought  in 
for  general  inspection  every  10  or  12  days,  at  which 
time  they  are  carefully  inspected  from  the  trolley 
wheels  to  the  rail,  and  at  this  time  all  light  repairs  are 
made.  By  light  repairs  I  mean  the  replacing  of  trollev 
wheels  and  poles;  placing  tips  on  circuit  breakers  or 
contactors;  light  switches;  blowing  out  and  cleaning 
of  controllers;  replacing  work  tips  and  fingers;  replac- 
nig  carbon  brushes  and  brushholders;  taking  clearance 
of  armatures ;  replacing  an  armature  in  a  split  frame 
motor;  blowing  out  of  motors;  the  cleaning  and  oiling 
of  brake  and  triple  valves;  inspection  and  repairs  to 
governors;  the  inspection  and  oiling  of  the  compres- 
sors, brake  cylinders  and  leathers,  piping,  etc..  the  in- 


spection and  light  repairs  to  the  brake  levers  and  pins, 
and  a  general  inspection  of  the  wheels.  By  having 
open  pit  construction  each  and  every  car  can  be  gone 
over,  or  inspected  every  night,  or  at  least  every  other 
night.  A  workman  can  cover  at  least  seventy  cars  and 
still  have  time  to  take  up  brakes  and  make  many  other 
minor  repairs.  Having  been  under  every  car  he  knows 
the  general  condition,  and  many  interesting  defects  are 
dicovered  that  would  not  have  been  found  from  the 
floor. 

MAIN    CAR  INSPECTION   AND  REPAIRS 

To  give  the  cars  a  thorough  and  general  overhaul- 
ing, the  proper  thing  to  do  is  to  raise  the  body  from 
the  trucks.  A  greater  portion  of  this  work  is  done 
when  the  car  is  brought  to  the  shop  for  wheeling  or 
the  turning  of  wheels.  Here  the  workmen  have  all  the 
facilities  for  making  any  and  all  repairs  from  the  trol- 
ley wheel  to  the  rail ;  and  while  the  body  is  removed 
all  parts  are  accessible  and  can  be  easily  inspected., 
Perhaps  the  most  interesting  work  is  the  general  over- 
hauling of  a  box  type  motor.  When  wheeling  a  car 
the  body  is  out  of  the  way,  the  brakes  have  been  "cut 
loose,"  the  axle  bearing  caps  and  gear  pans  have  been 
removed  and  it  is  only  necessary  to  remove  the  suspen- 
sion bolts  to  remove  the  motor  from  the  truck. 

SUPERVISION 

We  have  discussed  the  ideal  shop  with  all  the  lat- 
est improved  and  efficient  machinery,  tools,  etc.,  as  well 
as  conveniences  for  the  employes,  and  now  we  get 
down  to  the  point  of  supervision. 

We  must  have  live  energetic  men  in  charge  of  the 
various  departments,  men  with  good  dispositions  who 
are  capable  of  studying  the  manner  and  ways  of  em- 
ployes, to  get  their  good  will,  and  mingle  with  them, 
each  of  whom  should  bear  in  mind  at  all  times  that  he 
is  their  leader  and  as  such  is  responsible  to  his  super- 
iors. 

Discipline  must  be  maintained  at  all  times.  How- 
ever, the  man  in  charge  should  be  ready  to  meet  the 
employe  on  any  reasonable  matter  at  any  time,  and  if 
the  problem  is  too  big  for  him,  he  should  advise  the 
employe  that  he  will  take  the  matter  up  immediately 
with  his  superior,  and  then  carry  out  this  promise.  In 
order  to  manage  a  shop  properly  we  must  have  team 
work,  and  team  work  can  be  inaugurated  in  a  shop  nr 
plant  only  where  confidence  between  those  in  charge 
and  the  employe  has  been  fully  established.  Exper- 
ience has  taught  us  that  we  can  have  team  work  among 
our  men  and  have  their  confidence  and  respect  bv 
showing  them  that  we  have  confidence  in  their  work 
and  respect  for  them.  Respect  will  command  better 
discipline  in  one  day  than  arrogance  will  in  a  month. 
Discipline  built  on  the  proper  foundation,  and  tem- 
pered with  common  sense  will  result  in  team  work,  and 
IS  the  only  kind  that  lasts  and  pays  above  par  in  eff.- 
ciency,   confidence,   and  respect. 


v^ido  •£;<]<:  Cav^ 


M.  O'BKIEN 

Master  Mechanic, 
United  Railways  Company  of  St.   Louis 


THE  1920  model  car  built  in  the  shops  of  United 
Railways  Company  of  St.  Louis  and  recently 
placed  in  service  is  of  the  pay-as-you-pass, 
front-entrance,  side-exit  tyi)e.  Fifty  of  these  cars  are 
now  in  successful  service  on  a  heavy  duty  line.  The 
car  has  vertical  sides,  round  ends,  arched  roof,  and  is 
equipped  with  two  double-motor  trucks.     One  import- 


fittinjj  the  round  end  of  the  car.  The  front  portion  of 
the  car  has  2-j  feet  of  longitudinal  seating.  This  gives 
a  total  seating  capacity  of  fifty-nine  passengers.  The 
general  dimensions  of  the  car  are  shown  in  Table  I. 
The  motorman's  station  is  separated  from  the  re- 
mainder of  the  car  by  a  light  wood  and  glass  partition 
provided  with  a  sliding  door.     Suitable  hand  rails  at 


ant  feature  of  the  floor  plan  arrangement  is  a  single     the  conductor's  station  facilitate  the  movement  of  pas 
inside  step  at  both  the  front  entrance  and  the  side  exit 
door,  made  possible  by  ramping  the  floor  from  the  steo 
towards  the  center  of  the  aisle  and  also  along  the  aisle 


and  away  from  the  door  openings.  This  ramp,  which 
imposes  no  inconvenience  on  the  passengers,  makc.^ 
possible  the  use  of  the  single  inside  step  and  avoids 
the  use  of  folding  steps  or  a  dropped  platform  floor. 
It  is  expected  that  this  feature  of  the  car  will  reduce 
the  time  of  loading  and  unloading. 

The  front  entrance  has    a    double,    two-part,    out- 


sengers  and  the  collection  of  fares. 

CONSTRI'CTION   OF  CAR 

The  car  body  is  of  semisteel  construction  consist- 


FIG,    I — THE  PKTER  WIIT  FRO.\T-KNTR.\NCE,  SI11E-E.\rr  C.\U 

ward  folding  door,  which  is  air  operated.  At  the  sidf; 
exit  there  is  a  double  sliding  door,  also  air  operated, 
and  each  half  is  independently  controlled  by  the  con- 
ductor. The  entrance  and  exit  doors  have  a  clear  0]> 
ening  of  five  feet  and  are  divided  in  the  center  by  an 
aluminum  railing,  thus  providing  two  passage  ways  for 
passengers  either  boarding  or  alighting. 

The  conductor's  station  is  at,  and  just  forward 
from  the  center  exit  door.  With  this  arrangement 
the  entire  front  portion  of  the  car  from  the  conductor's 
station  is  available  as  loading  space,  as  passengers  are 
not  required  to  deposit  fares  in  the  fare  box  until  thev 
pass  the  conductor  going  either  to  the  rear  portion  of 
the  car  to  find  seats  or  in  leaving  the  car.  The  side 
exit  is  located  one  window  space  forward  from  the 
center  line  of  the  car  body,  thereby  increasing  the  seat- 
ing capacity  of  the  rear  or  "paid  portion"  of  the  car. 
This  was  deemed  a  desirable  feature. 

The  seating  arrangement  is  a  combination  of  cross 
and  longitudinal  seats.  The  rear  portion  of  the  car 
contains  sixteen  cross    seats  and    a    semicircular    seal 


ing  of  a  steel  bottom  framing,  up  to  and  including  the 
belt  rail,  built  up  from  standard  structural  shapes  and 
steel  plates.  The  jirincipal  feature  in  the  design  of  the 
steel  bottom  framing  is  the  use  of  a  12  gage  steel  plate 
30  in.  wide  reinforced  at  the  bottom  with  a  3  in.  angle 

TABLE  I— GENERAL  DIMENSIONS 


Overall    length    SO  ft.     6  in. 

Extreme    width     ^ 8  ft.  10  in. 

Height  from  floor  to  center  of  headlining.  .     7  ft.     8  in. 

I  rnck   wheel   base    5  ft-     4  '". 

Pivoted    distance    24  ft.     6  in. 

1  otal    wheel    base    29  ft.   10  in. 

Height   from  rail  to  step 15  in. 

Height  from  rail  to  top  of  trolley  board  ...   ir  ft.  10  in. 

Height   from  step  to  floor   12.5  in 

Weight   of   car,   complete    36 300  lbs. 

Seating   capacity    ^ 59 


forming  the  side  sill  and  at  the  top  by  a  2  in.  angle 
forming  the  belt  rail.  This  coinbination  forms  a  gird- 
er carrying  the  entire  weight  of  the  car  and  extends 
along  both  sides  and  around  the  rear  end  of  the  car 
forming  the  wall  of  the  car  below  the  belt  rail  coni- 
l)lete,  inside  and  outside,  ready  for  painting. 

lit  the  three  window  spaces  in  front  of  the  motor- 
man  a  40  in.  steel  i)late  is  used  to  provide  a  pocket  suf- 
ficiently deep  to  take  the  three  single-drop  sash.  In 
the  space  between  the  body  bolsters  the  floor  is  sup- 
ported by  seven  cross  sills,  each  made  up  of  a  4  m. 
channel  laid  flat  and  trussed  up  from  the  bottom  with 
a  0.5  in.  rod  and  two  9  in.  malleable  iron  queen  post^. 
The  reason  for  this  trussed  construction  is  to  gain 
proper  clearance  for  the  brake  levers  and  rods  withovu 
resorting  to  offsets  or  bends. 

In  the  space  between  the  rear  body  bolster  and  the 
rear  end  of  the  car  the  floor  is  supported  by  two  4  in. 
channels  set  on  edge  and  one  8  in.  channel  placed  flat. 
On  the  front  end  of  the  car  the  style  of  construction 
is  similar  except  for  the  necessary  framing  around  the 
step.  The  floor  at  this  end  of  the  car  is  supported  by 
one  4  in.  angle,  one  8  in.  channel  and  one  4  in.  channel 


October,  1921 


THE   ELECTRIC  JOURNAL 


469 


placed  flat.  Suitable  wooden  nailing  strips  are  bolted 
to  all  the  steel  cross  members  and  also  on  each  side  of 
the  steel  body  bolsters. 

For  diagonal  bracing  at  each  end  of  the  steel 
bottom  framing  2.5  in.  angles  and  0.25  in.  gusset  plates 
are  used.  To  provide  additional  strength  for  resist- 
ing bumping  and  drawbar  stresses,  each  end  of  the 
bottom  frame  is  re-enforced  with  a  0.25  by  12  in.  steel 
nose  piece  cut  to  lit  the  round  end  of  the  car  and  is  se- 
curely riveted  to  the  3  in.  angle  which  forms  the  side 
sill  and  also  extends  around  the  end  of  the  car. 

The  center  portion  of  the  bottom  frame  is  held 
square  by  four  diagonal  tie  braces  which  are  attached 
to  the  gusset  plates.  The  spaces  directly  over  the 
trucks  are  covered  with  No.  18  gage  black  sheet  steel 
which  is  securedly  fastened  to  the  bottom  side  of  the 
floor.  This  serves  the  double  purpose  of  a  diagonal 
brace  and  as  fire-proofing  the  wooden  fioor. 

To  carry  the  load  stresses  around  the  door  open- 
ings, steel  framing  is  used.  The  center  door  frame  is 
made  up  of  two  <)  in.  channels  tied  together  at  the  top 
by  a  5  in.  bv   ^  in.  angle  and  at  the  bottom  by  a  6  in. 


FIG.  2— SE.\TING  .'1RR.\NGEMENT  OF  THE  PAY  .\S  PASS  TYPE  CAR 

by  3.5  in.  angle  all  of  which  are  in  turn  securely  riveted 
to  the  side  plates,  belt    rails,    side    sill    and    cross    sills. 

At  each  end  of  the  straight  portion  of  the  car  bod\-, 
pier  posts  of  6  in.  channels  are  riveted  to  the  side  plates 
and  extend  up  to  the  top  plate  and  letter  panel  to  which 
they  are  securelv  attached  with  bolts.  These  pier 
posts  together  with  the  steel  door  frames  stiffen  and 
prevent  racking  of  the  upper  portion  of  the  car  body. 

Since  the  steel  bottom  framing  is  provided  with 
the  necessary  strength  to  resist  all  ordinary  working 
stresses  encountered  by  the  car  in  service  the  wood 
superstructure  of  the  car  is  made  as  light  as  possible. 
The  side  posts  and  car  lines  are  of  ash,  while  the  pier 
post,  door  frame  fillers  and  floor  nailing  pieces  are  of 
oak.  The  top  plate  and  flooring  are  of  long  leaf  vello\v- 
pme,  the  letter  panel  and  drip  rail  are  of  poplar. ' 

The  carlines  at  each  post  are  re-enforced  with  a 
1.5  m.  by  0.25  in.  steel  car  line  with  a  foot  at  each  end 
bolted  to  the  top  plate.     The  sash  and  interior  finish 


is  of  cherry  stained  and  \arnished  which  harmonizes 
with  the  light  green  headlining  and  gives  the  car  a  very 
])leasing  appearance.  The  seats,  both  cross  and  longi- 
tudinal, are  of  rattan  over  hair  felt  and  coiled  springs. 
This  car  is  equipped  with  two,  double  motor,  in- 
side hung  trucks  of  a  new  design  developed  by  the 
Commonwealth  Steel  Company  in  co-operation  with 
the  Railway  Company's  engineers.  The  principal  fea- 
ture of  the  truck  is  a  main  frame  made  in  a  single  steel 
casting,  eliminating  all  the  usual  connecting  bolts  and 
rivets  and  at  the  same  time  making  it  impossible  for 
the  truck  to  get  out  of  square.  The  truck  is  of  the 
full  equalized,  arch  bar  type  similar  to  those  u.sed  un- 
der Pullman  and  other  steam  railway  passenger  cars, 
wdiich  insures  easy  riding  and  freedom  from  derail- 
ment, often  caused  by  trucks  not  being  able  to  adjuu 
themselves  to  irregularities  in  the  track. 

COUPLING  ARRANGEMENT 

A  built  up  wood  and  steel  bumper  3  ft.  9  in.  \\\(\\' 
and  extending  out  6  in.  in  front  of  the  car  body  is  pro- 
vided to  form  a  support  for  the  plain,  cast-steel,  draw- 
bar pocket  and  also  as  a  protection  for  the  headlight 
and  front  end  of  the  car.  The  rear  draw  coupler  is 
made  to  swing  and  is  of  a  special  design  developed  by 
the  United  Railways  Company.  The  coupler  is  3  ft.  8  in. 
long  and  pivoted  4  ft.  4  in.  from  the  end  of  the  car. 
This  keeps  the  outer  end  of  the  coujiler  8  in.  under  the 
car  bodv,  making  it  impossible  for  boys  to  stand  here 
and  ride.  The  coupler  operates  on  the  bayonet  socket 
princijile  and  no  coupling  pin  is  required.  The  cast 
steel  extension,  carried  on  hooks  under  the  car  body, 
has  a  T-head  on  one  end  which  is  inserted  in  the  open 
end  of  the  coui)ler  and  given  a  quarter  turn.  The 
other  end  of  the  extension  is  made  flat  to  fit  the  coup- 
ler pocket  at  the  front  end  of  the  car.  This  front 
coupler  pocket  is  standard  on  all  of  the  Company's 
cars  and  the  use  of  the  extension  makes  it  possible  to 
couple  the  new  car  to  any  of  the  older  types  of  cars. 

ELECTRICAL    EQUIPMENT 

The  electricrd  equipment  consists  of  four  25  hp 
motors,  a  controller  with  ratchet  switch  for  operating 
the  line  switch  and  the  safety  door  interlock  system. 
A  magnetic  blowout  main  switch  is  placed  in  the  mo- 
torman's  cab  for  use  in  opening  the  main  power  circuit 
by  hand  when  desired.  The  overload  relay  on  the  line 
switch  takes  the  place  of  a  circuit  breaker  and  causes 
the  line  switch  to  break  the  circuit  under  the  car,  thus 
eliminating  all  noise  and  flash  from  the  car  interior. 

The  safetv  door  interlock  system  makes  it  impos- 
sible to  start  the  car  until  all  d(.>ors  are  closed.  .Should 
the  power  be  thrown  olf  for  any  reason  while  the  car 
is  moving,  with  the  controller  handle  on  any  but  the 
first  point  it  is  necessary  for  the  motorman  to  return 
the  handle  to  the  first  point  before  the  line  switch  will 
close  the  circuit.  This  is  an  additional  safeguard 
against  injury  to  the  motors  or  other  equipment. 


W©a 


VoiitilntBd 


J.  S.  DEAN 

Motor  Engineering"  Dep. 
Westinghouse  Electric  &  Mfg.  Co. 


'S 


WHEN  the  ventilated  railway  motor  first  came 
into  use,  there  was  considerable  discussion 
regarding  tlie  amount  of  dust  and  dirt  that 
would  collect  and  settle  inside  the  motor,  and  its  effect 
upon  the  insulation  and  the  efficiency  of  the  ventila- 
tion. Some  operators  contended  that  the  motor  would 
be  kept  cleaner  due  to  the  current  of  air  passing 
through  it,  basing  their  statement  on  their  experience 
with  some  of  their  non-ventilated  motors  operating 
with  top  and  bottom  commutator  covers  open,  which 
gave  practically  no  trouble  from  dirt  collecting  inside 
the  motor.  Other  operators  were  skeptical  and  pre- 
dicted that  this  type  of  motor  would  collect  dirt  and 
foreign  particles  which  in  due  time  would  give  more 
or  less  trouble. 

After  several  years  of  operation,  experience  has 
shown  that  considerable  dirt  is  drawn  through  the 
motor  and  a  certain  percentage  of  it  lodges  inside.  If 
this  statement  needs  confirmation,  a  visit  to  some 
railwaj'  shop  during  the  overhauling  period  when  some 
of  the  ventilated  armatures  are  being  blown  out  and 
cleaned  by  the  use  of  compressed  air  would  be  illumin- 
ating. One  shop  has  been  fitted  up  to  do  this  work 
outside  of  the  building.  Another  shop  places  these 
armatures  in  an  enclosed  receptacle  which  is  attached 
to  a  suction  pump  to  carry  off  the  dirt  during  the  clean- 
ing process.  This  same  condition,  however,  applies 
to  all  types  of  motors,  except  on  specially  designed 
enclosed  motors.  Nevertheless,  although  considerable 
dirt  lodges  in  these  motors,  apparently  it  has  caused 
no  serious  trouble  to  the  windings  nor  has  it  noticeably 
decreased  the  efficiency  of  the  ventilation. 

Side  Wear  of  Carbon  Brushes — A  comparatively 
short  time  after  the  ventilated  motors  were  put  into 
service  on  a  number  of  properties  throughout  the  coun- 
tr}',  nuinerous  inquiries  were  received  regarding  the 
comparative  short  life  of  the  carbon  brushes.  A  typi- 
cal example  is  as  follows: — "Enclosed  you  will  find 
sample  carbons  taken  from  our  motors  which  have 
been  in  service  only  about  four  months.  We  are 
alarmed  regarding  the  short  life  of  these  carbons  when 
compared  with  the  life  of  carbons  of  our  old  type  non- 
ventilated  motors  which  averages  from  i  to  1.5  years. 
You  will  note  that  these  carbons  are  badly  worn  on  the 
sides  but  show  very  little  wear  on  the  end."  Some 
t}'pical  samples  of  worn  carbons  as  referred  to  above 
are  shown  in  Figs,  i  and  2.  These  represent  different 
grades  of  carbons  received  from  operators  in  different 
parts  of  the  country  and  indicate  that  this  condition  is 
quite  general. 


COMPARATIVE    LIFE    OF    CARBONS — NON-\'ENTILATED 
AND  VENTILATED  MOTORS 

Non-Ventilated  Motors — In  the  early  days,  when 
the  plain  hard  carbon  brush  was  used  as  a  matter  of 
necessity  in  connection  with  commutators  having  flush 
mica,  the  brush  life  was  comparatively  short,  and  main- 
tenance on  carbons  and  commutators  was  relative- 
ly high,  but  these  figures  were  never  questioned  under 
these  conditions  of  operation.  With  the  advent  of 
the  commutating-pole  motor  with  its  improved  com- 
mutation, undercut  mica,  and  the  adoption  of  high- 
grade  graphitized  carbon  brushes  there  was  a  decided 
increase    in    the    brush    life.     In    some    cases,    carbon 


iH  Ji 


FIG.   I— COMPARATIVE  CARBON  SIDE  VVE.\R  WITH   AND  WITHOUT 

SHUNTS 

FIG.    2— TVPIC-^L    EX.\MPLES    OF    CARBON    SIDE    WEAR    AS   FOUND    IN 

SERVICE 

brushes  have  been  reported  to  have  made  over  150000 
miles  in  service.  However,  in  general,  the  brush  lite 
will  average  between  forty  and  fifty  thousand  miles  or 
from  one  to  1.5  years  of  service. 

Ventilated  Motors— Facing  these  facts  it  is  little 
wonder  that  some  operating  men  become  alarmed 
when  they  found  it  necessary  to  change  the  carbons 
on  their  ventilated  motors  after  three  or  tour  months 
of  service  on  account  of  the  side  wear  of  carbons 
which  showed  very  little  end  wear.  This  wear  has  de- 
veloped on  various  makes  of  high  grade  carbons  on 
different  types  of  ventilated  motors  and  is  not  con- 
fined to  properties  in  any  definite  section  of  the  coun- 
try. However,  with  some  types  of  ventilated  motors 
on  certain  properties,  this  wear  is  more  apparent  than 
on  other  properties.  As  was  found  in  connection 
with  the  non-ventilated  motor,  so  it  is  true  of  the  ven- 


October,  1921 


THE   ELECTRIC  JOURNAL 


A7^ 


tilated  motor,  that  carbon  brush  Hfe  varies.  On  some 
properties  as  high  a  life  as  30000  miles  has  been  re- 
ported while  on  others  as  low  as  4  000  miles.  In  gen- 
eral, the  reported  average  life  is  much  lower  than  on 
the  non-ventilated  motor,  and  averages  of  about  eight 
to  ten  thousand  miles  may  be  taken  as  consei-vative 
figures. 

SUGGESTED    PROBABLE   CAUSE  OF   THIS   SIDE    WEAR 

Electrical  Action — It  has  been  suggested  that,  due 
to  a  heavy  current  of  electricity  passing  from  the  side 
of  the  carbons  to  the  carbon  box,  the  burning  action 
on  the  carbon  rapidly  cuts  away  the  sides,  which  makes 
it  necessary  to  renew  the  carbons  before  they  are  worn 
out  lengthwise;  this  heavy  current  probably  being  due 
to  some  or  all  of  the  following  reasons : — 

I — Light  weight  ventilated  motor,  where  all  parts  are 
reduced  to  a  minimum  with  close  design  limitations. 

2 — High  continuous   ratings  of  the  motor,  due  to  the 
improved  ventilation. 

3 — Close  application,  working  the  carbons  at  high  cur- 
rent density. 

4 — Relatively  high  accelerating  currents. 

To    check    this    question    of    suggested    excessive 

currents  being  responsible  for  this  side  wear,  tests  were 

made  on  ventilated  motors  of  the  same  type  operating 

under  the  same  service  conditions,    (i)    with  carbons 


b — Bearing  on  inner  edge  of  top  of  carbon,  Fig.  8. 
c — Bearing'  on  outer  edge  of  top  of  carbon.  Fig.  g. 
5 — ^Wide,    flat,    brazed    tip    with    edges    well    rounded, 
Fig.  10. 

On  account  of  the  troubles  experienced  in  con- 
nection with  the  operating  conditions  under  which 
these  tests  were  made,  results  were  not  conclusive,  but 
all  of  the  tendencies  seemed  to  indicate  that  the  shape 
of  the  tip  had  no  effect  on  the  side  wear  of  the  car- 
bons. One  thing  in  connection  with  these  tests  that 
showed  up  very  noticeably  was  that  the  flat  tip  de- 
veloped very  little  destructive  action  on  the  top  of  the 
carbons. 

Mechanical  Action — It  has  been  intimated  that 
this  side  wear  might  be  caused  by  mechanical  action 
brought  about  by  the  constant  rubbing  and  chafing  of 
the  carbons  against  the  side  of  the  brushholder  box, 
due  to  soine  of  the  following  reasons : — 

-Large  initial  clearance  between  carbon  and  carbon 


box. 


2 — Uneven  commutator  surface. 

3 — Commutator  out  of  round. 

4 — Too  light  spring  pressure. 

5 — Rough  finish  on  inside  of  carbon  box. 

6 — Worn  and  loose  armature  bearings. 

7 — Severe  service  conditions. 

8 — Run  down  condition  of  track  and  road  bed. 

9 — Careless  handling  of  the  equipment. 


^^     ^ 


5 

FIG. 

b 

FIG. 

7 

FIG. 

8 

TYPES 

OF 

CONTACT 

TIPS 

AND 

BR  US 

H  HOLDER 

PRESSURE 

FINGER 

having  shunts  or  pigtails  to  take  care  of  the  increased 
current,  and  (2)  with  plain  unshunted  carbons.  The 
results  obtained  from  these  test  carbons  which  were 
in  service  approximately  three  months  are  shown  in 
Fig.  I  and  show  practically  no  difference  in  the  side 
wear  of  the  two  sets  of  carbons.  This  indicates  that 
the  current  carrying  capacity  of  the  shunts  does  not 
help  this  condition. 

In  another  series  of  tests*  it  was  found  that  with 
the  carbon  box  lined  with  insulating  material,  the  car- 
bons in  these  boxes  showed  signs  of  side  wear.  These 
tests  seem  to  confirm  the  fact  that  the  wear  exists 
where  there  is  no  transfer  of  current  from  carbon  to 
carbon  box. 

Shape  of  Contact  Tip  on  Pressure  Finger — It  was 
suggested  by  one  of  the  carbon  manufacturers  that 
the  shape  of  the  contact  tip  on  the  pressure  finger 
might  be  partly  responsible  for  this  side  wear.  To 
check  this  point,  tests  were  made  on  a  number  of  dif- 
ferent types  of  tips  as  outlined  below  :— 

1— Rounded  face  extruded  metal  tip.  as  follows  :— 
u^,V;''l'  '^^^  extended  over  side  of  tip.  Fig.  3. 
b— With  ears  flush  with  side  of  tip,  Fig.  4. 

2— I'lat  riveted  tip,  Fig.  5. 

3— Adjustable  flat  tip,  Fig.  6. 

4— Flat  brazed  tip,  as  follows:— 

a— Bearing  flat  on  top  of  carbon,  Fig.  7. 


All  of  the  above  will  tend  to  cause  more  or  less 
wear  on  the  sides  of  carbon  brushes,  but  it  must  be  re- 
membered that  all  of  these  conditions  are  also  found 
in  connection  with  the  operation  of  the  non-ventilated 
motors,  which  would  indicate  that  this  alone  is  not  re- 
sponsible for  the  side  wear  of  the  carbons  on  the  ven- 
tilated motors. 

Action  of  Dust  and  Dirt— By  a  careful  study  of 
this  subject  from  all  suggested  angles  and  by  means  of 
a  process  of  elimination,  the  one  outstanding  factor 
characteristic  of  the  ventilated  motor  which  is  not  as- 
sociated with  the  non-ventilated  motor  is  the  com- 
paratively large  ainount  of  dust  and  dirt  being  drawn 
through  the  motor  by  the  action  of  the  ventilating  fan. 
Observations  and  tests  which  have  been  made  from 
time  to  time  have  produced  some  confirming  evidence 
which  indicates  that  dust  and  dirt  play  an  important 
part  in  the  side  wear  of  carbons.  These  are  as  fol- 
lows : — 
Non-Ventilated  Motor—Operating  unlh   Top   Covers  Off*— 

I — Pronounced   streaking   was   found   on   the   sides   of 
the  carbons. 

2 — The  above  condition   (i)   was  noted  on  carbons  in 

*Explained  in  detail  in  an  article  on  "The  Action  of  Dirt 
on  Railway  Motor  Carbons"  in  the  Journal  for  March,  1918. 
Ventilated  Motors 


THE   ELECTRIC  JOURNAL 


Vol.  X\III,  No.  lo 


insulated  boxes  where  there  was  no  passage  of  current 
between  the  brush  and  the  box. 

3 — With  dust  and  dirt  chutes  provided  for  brush- 
holders,  no  streaking  was  found. 

Sand  particles  were  found  lodged  in  grooves  on  side 
of  carbon. 

I — A  comparatively  large  amount  of  dirt  was  found 
inside  of  the  motor. 

2 — With  dust  and  dirt  chutes  provided  for  brush- 
holders,  the  side  wear  was  reduced. 


the  ventilation  and  is  known  as  the  parallel-type  ven- 
tilation. With  this  system  the  air  is  drawn  in  at  the 
commutator  end  through  a  hole  in  the  housing  or  mo- 
tor frame,  part  passing  through  the  air-gap  and  around 
the  field  coils,  and  part  passing  through  the  longitudia- 
al  air  ducts  in  the  armature.  By  the  action  of  the 
larger  diameter  fan  all  of  the  air  is  blown  out  at  the 


FIG.     II — .-KKIES     VE.\TIL.\TION" 

.■\rmature  with  single  fan  and 
longitudinal  air  ducts.  Air  inlet  lo- 
cated at  pinion  end  top  side  of  hous- 
ing. 


FIG.      12 — rAkALIJI.     \  KN'TIL.\TIO>r 

.•\rmature  with  fan  and  longitudi- 
nal air  ducts.  Wr  inlet  located  at 
commutator  end  under  side  of  hous- 
ing. 


FIG-    13 — P.\R.\LLEL   VENTILATION 

Armature  with  fan  and  longitudi- 
nal air  ducts.  Air  inlet  located  at 
commutator  end  under  side  of  hous- 
ing. 


3 — More  rapid  side  wear  was  noted  in  the  summer 
than  in  the  winter,  indicating  that  the  condition  of  the  sur- 
face of  the  road  bed  enters  into_the  question. 

4 — There  was  a  noticeable  diflference  in  carbon  side 
wear,  depending  upon  the  location  of  the  air  inlet  on  the 
motor  frame. 

5 — Straining  the  dirt  at  the  air  inlet  reduced  carbon 
side  wear. 

6 — On  single-end-operated  cars,  carbon  side  wear  was 
more  pronounced  on  Nos.  3  and  4  motors  than  on  the  Xos. 
I  and  2  motors. 

RESULTS  OF  SERVICE  TEST 

Under  the  sub-heading  of  "Ventilated  Motors"  the 
statement  covered  by  condition  (i)  was  discussed  in 
the  beginning  of  this  article  and  needs  no  further  com- 
ments. Conditions  (2)  and  (3)  were  arrived  at  by 
service  tests  and  observation.  The  remaining  three 
conditions  will  be  discussed  more  in  detail  to  give  the 
available  information  leading  up  to  these  statements. 

Types  of  Ventilated  Motors — Condition  4 — The 
earlier  designs  of  ventilated  railway  motors  were  laid 
out  with  what  is  commonly  known  as  the  series  type 


FIG.     14 — CURLED    H.MR    BEFORE    .\XU    .\FTER    U.-iING 

A — Clean  curled  hair  before  placing  in  air  inlet. 

B — Curled  hair  with  dirt  collected  in  service. 

C — Fine  dirt  collected  by  curled  hair  in  service  at  air  inlet. 

of  ventilation.  The  air  is  taken  in  at  the  pinion  end 
top  side  of  the  frame,  drawn  forward  through  the  air- 
gap  and  around  the  field  coils  and  then  back  through 
the  longtitudinal  air  ducts  in  the  armature  to  the  rear 
of  the  motor  where  it  passes  out  of  the  frame  as  shown 
in  Fig.  II.  With  this  type  of  ventilated  motor,  tlic 
carbon  side  wear  is  not  so  noticeable. 

In  later  designs  of  ventilated  motors,  the  ventilat- 
ing scheme  was  changed  to  iinprove  the  efficiency  of 


rear  of  the  frame,  as  shown  in  Figs.  12  and  13.  With 
this  later  type  of  ventilated  motor,  carbon  side  wear 
is  more  pronounced  than  with  series  ventilation,  pos- 
sibly for  the  following  reasons : — 

I — Increased  amount  of  air — approximately  40  to  50 
percent  more  volume  of  air  than  with  the  series  type  of 
ventilation. 

2 — Less  opportunity  for  dirt  to  settle  before  reaching 
the  brushes. 
Straining  the  Air  at  Inlet  of  the  Motor-Condition 

\'o'.  5 — In  connection  with  air  brake  systems  it  has 
been  found  necessary  to  use  a  strainer  filled  with 
curled  hair  to  provide  clean  air.  This  idea  suggested 
to  a  master  mechanic  the  thought  that  straining  the  air 
at  the  inlet  of  the  motor  would  clean  it  and  reduce 
the  carbon  side  wear  which  previous  observation  and 
tests  indicated  was  due  to  dirt.  Tests  were  made  mi 
a  car  equipped  with  ventilated  motors  having  the 
parallel  type  of  ventilation  and  the  air  inlets  packed 
with  clean  curled  hair,  such  as  is  used  in  the  strainer 

TABLE    I— DEGREES    INCREASE   IN    TEMPERATURE 
PRODUCD  BY  A  CURLED  HAIR  STRAINER 


bo 

( 

0 

c; 

*-   u 

^ 

(^ 

-  ^ 

r;  a 

0  "V 

^  2 

t: 

e 

i- 

B  0 

Ui'^ 

0 

u 

e 

£ 

< 

< 

d 

2.S 

5 

"•5 

II-5 

7-5 

5 

on  the  air  brake  system.  Reports  from  this  test  show 
the  following  conditions  and  results: 

I— The  life  of  the  carbons  was  trebled. 

2— The  commutator  and  brushholder  wear  were  re- 
duced. ...         a:   •     t. 

2— The   ventilation   of   the   motors   was   still    suthcient 

for  the  service. 

These  motors  are  regularly  inspected,  and  when 
the  curled  hair  becoines  clogged  with  mud  and  dirt  it 
is  removed  and  new  hair  installed.  To  show  to  what 
extent  this  curled  hair  strained  and  kept  tlie  dirt  from 
passing  through  the  motor,  samples  before  and  after 
using,  and  also  some  of  the  strained  dirt,  were  photo- 
graphed and  are  shown  in  Fig.  14.     This  test  indicates 


October,  1921 


THE   ELECTRIC  JOURNAL 


A7Z 


that   when  only  clean   air  is  allowed  to  pass  through 
the  motor  the  side  wear  of  carbons  is  greatly  reduced. 

Comparative  shop  tests  were  made  on  a  ventilated 
motor  without  and  with  clean  curled  hair  which  shows 
an  increase   in   temperatures   as   measured   by   a   ther- 
mometer, due  to  the  air  inlet  being  filled 
with  clean  curled  hair,  as  given  in  Table 
I.  These  figures  cannot  be  used  as  final, 
as   it   will   naturally   follow  that   as   the 
hair  gets  filled  and  clogged  with  dirt  the 
temperature  will  increase  until  the  dan- 
ger point  is  reached.     Where  the  air  is 
strained  by  this  means  there  is  danger 
of  reducing  the  efficiency  of  the  ventila- 
tion and  producing   overheating   of    the 
motors,  and  this  would  be  more  serious 
than  removing  a  few  carbons  on  account 
of  side  wear.     Therefore,  it  should  be 
definitely   understood  that   this  practice       '^ 
is  not  recommended  as  a  general  remedy 
for  side  wear  of  carbons.  Common  sense 
will  tell  the  railway  operating  man  that  under  certain 
conditions  this  scheme  may  work  satisfactorily,  but  in 
general  it  should  not  be  followed  as  common  practice. 

Side  ]]'car  as  Affected  by  Position  of  Motor  on 
Car-Condition  A'o.  6. — A  strong  current  of  air  i< 
carried  alcmg  with  a  moving  street  car,  sweeping  with 


bon  brushes,  in  connection  with  the  above  condition 
shows  a  \ery  marked  difference  in  the  carbon  side 
wear  of  the  various  motors  mounted  on  the  same  car. 
This  is  especially  noted  in  the  case  of  cars  running  in 
one  direction,  on  which  the  carbons  of  the  motors  on 


/Va  3 Motor 


4  Mo-fvr 


No.  /  Motor 


No  Z  Motor 


No.  3  Motor 

FIG.    IS — FRONT    VIEW    OF   C.^RBON    BRUSHES 

Showing  side  wear. 
It  particles  of  dust,  which  may  entirely  envelop  the 
rear  end  of  the  car.  With  dirty  streets  and  on  dusty 
roads  in  the  country  this  condition  is  most  pronounced. 
On  the  other  hand,  on  well  sprinkled  streets  and  oiled 
roads  the  dust  and  dirt  are  settled  and  this  condition 
IS  practically  eliminated.     A  study  of  side  wear  on  car- 


KIG.    16 — SIDF.    VIEW    OF   C.\REO.N    BRUSHE.s 

Showing  side  wear, 
the  rear  truck  wear  more  rapidly  on  the  side  than  those 
of  the  leading  truck.  This  is  brought  out  fairely  in 
Figs.  15  and  16,  which  shows  a  set  of  test  carbons  oper- 
ating in  city  ser\ice,  with  single  end  operation  of  paral- 
lel tyiie  ventilated  motors,  all  carbons  being  of  the  same 
grade.  The  tests  were  made  in  the  south  during  the 
months  of  August  to  December.  The  mileage  and  av- 
erage side  w^ear  of  these  carbons  is  given  in  Table  II. 
These  tests  tend  to  show  that  the  action  of  the  dust 
and  dirt  has  something  to  do  wdth  carbon  side  wear. 
The  No.  3  and  No.  4  motors  on  single  end  cars,  always 
lieing  on  the  trailing  truck,  where  they  are  subjected 

TABLE  II— EFFECT  OF  POSITION   ON  CAR  ON   SIDE 
WEAR 


Position  on  Car 

Mileage 

Av.   Side   Wear 


Alotor 
No.  I 

6524 
0.006" 


Motor 
No.  2 

6524 
0.012' 


Motor 
No.  3 

6524 
0.068" 


Motor 
IMotor 

6090 
0073" 


to  more  dust  and  dirt,  develop  more  rapid  side  wear 
of  carbons  than  the  No.  i  and  2  motors  on  the  leading 
truck. 

CONCLUSIONS 

We  are  not  justified  in  making  the  positive  state- 
ment that  all  carbon  side  wear  is  caused  by  the  action 
of  dust  and  dirt.  Associated  with  the  dust  and  dirt 
is  the  ever-present  mechanical  vibration,  and  no  doubt 
some  burning  action  due  to  the  electrical  current,  all 
of  which  are  contributing  factors.  However,  we  be- 
lieve that  the  evidence  shows  that,  if  the  action  of  the 
dust  and  dirt  could  be  eliminated,  side  wear  on  the  car- 
bons could  be  obtained  which  would  compare  favorably 
with  conditions  now  existing  on  the  non-ventilated  type 
of  motors.  It  must  be  borne  in  mind  that  side  wear  of 
carbons  is  relatively  unimportant,  when  compared 
with  the  marked  advantages  of"  parallel  ventilated  mo- 
tors over  series  ventilated  and  enclosed  motors. 


**Explained  in  detail  in  an  article  on  "The  Action  of  Dirt 
on  Railway  Motor  Carbons"  in  the  Journal  for  March,  1918. 


T 


or 


olr^lvt  ^oi'vlco  on  j^loc'xii^jc  llailvya 


r.  H.  STOKKEL 

Railway  Department, 
Westinghouse  Electric  &  Mfg.   Company 

haulinf 


THERE  are  three  principal  means  of 
freight  overland,  viz: — by  the  steam  railroad, 
the  electric  railway  and  the  motor  truck,  each  of 
which  has  its  particular  field  of  efficiency  and  econ- 
omy, depending  upon  local  conditions  and  requirementr,, 
and  the  nature  and  volume  of  tonnage  available.  It  is 
generally  realized  that  no  single  means  or  method  of 
conveying  goods  can  be  expected  to  fulfill  all  the  re- 
quirements of  industrj'  and  trade,  but  that  there  must 
be  a  co-operative  co-ordination  of  the  various  forms 
of  transportation  to  secure  most  satisfactorj'  and  econ- 
omical results. 

In  the  future  transportation  scheme  of  this  coun- 
try, the  electric  railway  is  destined  to  play  an  exceed- 
ingly important  part.  The  past  few  years  have 
demonstrated  conclusively  the  value  and  importance  to 
the  communities  or  districts  served,  of  electric  line 
freight  and  express  service,  and  as  a  result  shippers  are 
making  organized  eflforts  to  secure  expansion  of  oper- 
ations and  increases  in  facilities,  and  are  also  advocat- 
ing and  giving  their  support  to  legislation  tending  lo 
remove  the  unreasonable  and  unwarranted  restrictions 
imposed  by  municipalities  and  other  governmental 
authorities,  on  electric  lines  engaged  in  this  branch  of 
service. 

Communities  which  are  now  served  by  competing 
steam  and  electric  roads,  are  fortunate  in  that  shippers 
are  able  to  secure  not  only  more  expeditious  and  satis- 
factory service  by  using  the  electric  line,  when  such 
line  is  engaged  in  transporting  freight,  but  by  using 
this  service  entirely  on  shipments  to  and  from  nearby 
markets,  they  are  benefitting  themselves  further  by  re- 
lieving terminals,  cars  and  other  facilities  of  the  steam 
roads  of  short  haul  unrenumerative  tonnage, 
thereby  enabling  such  roads  to  facilitate  the  movement 
of  and  improve  service  on  the  more  profitable  long 
haul  heavy  tonnage.  Available  operating  cost  data 
indicates  that,  in  addition  to  being  able  to  render  bettei 
and  more  satisfactory  service  on  short  haul  freis^ht 
traffic,  the  electric  line  can  handle  and  transport  such 
traffic  with  splendid  net  financial  results  while,  on  the 
other  hand,  the  steam  road  is  handling  such  tonnage 
at  a  loss  when  for  destinations  less  than  75  or  100 
miles  distant.  This  is  due  to  the  fact  that  the  steam 
road,  by  the  very  nature  of  the  service  which  it  is 
called  upon  to  render,  must  provide  rolling  stock,  road 
bed,  track  and  terminal  facilities  of  sufficient  size  and 
capacity  to  take  care  of  maximum  demands  and  to 
enable  them  to  take  advantage  of  the  economies  result- 
ing from  the  hauling  of  heavy  tonnage  trains.  This 
heavy  and  expensive  equipment  must  also  be  used  for 
hauling  the   comparatively   light   loads   for   short   dis- 


tances. It  has  been  found  that  the  average  loading  of 
merchandise  in  steam  road  cars  is  but  10000  lbs.  for 
which  equipment  having  a  capacity  of  from  60000  to 
100  000  lbs.  must  be  used.  Inability  to  utilize  to  the 
fullest  extent  the  tonnage  capacity  of  rolling  stock  re- 
sults in  expensive  operation,  which  together  with  the 
necessarily  heavy  overhead,  interest  and  taxes  makes 
the  handling  of  short  haul  business  unrenumerative. 

On  the  other  hand,  the  electric  railway  with  its 
smaller  mileage  does  not  require  as  extensive  terminals, 
nor  as  heavy  equipment,  roadway  or  track,  has  much 
less  overhead  expense,  interest  and  taxes  to  provide 
for,  and  can  therefore  conduct  a  freight  business 
profitably,  even  at  the  same  rates  as  the  steam  roads. 
The  revenues  from  this  branch  of  service  are  of  ma- 
terial aid  and  assistance  in  meeting  the  costs  of  main- 
tenance, power,  supervision,  etc.     Electric  line  freight 


FIG.    I — 60-TON  ELECTRICAL  FREIGHT  LOCOMOTIVE 

operation  has  other  advantages  to  the  operators  them- 
selves besides  the  net  financial  results.  It  tends  10 
bring  about  closer  relations  with  communities  and  in- 
dividuals along  the  line,  and  leads  to  better  understand- 
ing and  the  co-operation  of  civic  bodies,  farmers  asso- 
ciations, etc.,  to  the  benefit  of  all  concerned.  Devel- 
opement  of  the  feeling  that  the  public  and  public  utili- 
ties have  common  interests,  is  a  valuable  asset. 

While  most  electric  lines  were  planned  and  con- 
structed for  passenger  service,  such  construction  docs 
not  prevent  operation  of  a  successful  freight  business. 
The  territory  covered  by  practically  every  line  will 
produce  tonnage  which  can  be  further  developed  by 
consistent  and  intelligent  effort  through  an  efficient 
traffic  department.  As  a  common  carrier,  the  electric 
railway  owes  it  to  itself  as  well  as  to  the  communities 
served,  to  place  at  the  disposal  of  the  public  every  fa- 
cility within  its  power.  Roadway,  track,  distribution 
lines  and  power  plants  are  already  in  existence,   and 


October,  1921 


THE  ELECTRIC  JOURNAL 


475 


other  facilities  necessary  for  freight  handhng,  such 
as  terminals,  freight  rolling  stock,  and  possibly  some 
additions  or  changes  in  meeting,  passing  or  other 
tracks,  can  be  provided  at  comparatively  small  expense. 
Usually  no  additions  to  power  plant  or  distribution 
lines   are   necessary,   as    freight   trains   can  be   run   at 


night  or  during  off  peak  hours,  thereby  improving  the 
load  factor  of  the  generating  station,  and  at  the  same 
time  utilizing  tracks  and  other  facilities  which  would 
otherwise  be  idle. 

In  conducting  a  freight  or  express  business,  or 
both,  it  is  important  that  special  consideration  be  given 
to  the  selection  or  construction  of  terminals,  motive 
equipment  and  other  rolling  stock,  train  schedules  and 
traffic  department  organization.  One  of  the  greatest 
items  of  expense  of  freight  handling  is  the  terminal 
or  warehouse  cost,  but  this  can  be  reduced  to  a  mini- 
mum by  a  thorough  study  of  the  requirements  and 
careful  planning  of  warehouses  and  track  lay-out.  Ii 
is  not  necessary  or  advisable  to  locate  freignt 
houses  in  congested  business  districts  on  property 
more  valuable  for  other  purposes,  but  experience  has 
shown  that  no  loss  in  tonnage  results  from  locating 
ni  outlying  districts  on  less  expensive  ground,  where 
sufficient  property  can  be  had  to  provide  adequate  fa- 
cilities and  permit  of  future  expansion  and  develope- 
ment.  It  has  been  demonstrated  that  at  larger  termin- 
als, greatest  economy  in  operation  and  efficiency  can 
be  secured  by  having  separate  warehouses  for  in  and 
out  bound  shipments,  but  where  this  is  not  possible, 
excellent  results  can  be  obtained  by  dividing  the  ware- 
house space  into  two  sections;  one  for  unloading  and 
delivering,  and  the  other  for  receiving  and  loading. 
This  plan  makes  for  less  confusion  and  delay  in  making 
deliveries  to  patrons,  and  the  floor  of  the  outbound  sec- 
tion is  left  practically  free  of  encumbrances,  thus  per- 
mitting the  receiving,  weighing  and  loading  of  ship- 
ments direct  from  dray  into  cars. 

Decided  economies  are  also  possible  through  pro- 
viding ample  trackage  to  serve  the  warehouse.  Wheie 
tonnage  warrants  the  loading  of  a  number  of  cars 
each   day,   sufficient   trackage   should   be   provided    for 


enough  cars  so  that  all  shipments  can  be  handled  di- 
rect from  trucks  to  cars  with  a  single  operation,  thus 
avoiding  e.xtra  expense  of  rehandling.  Best  results 
are  obtained  where  two  or  three  tracks  are  laid  paral- 
lel to  the  warehouse  platform,  with  connections  for 
shifting  cars  at  both  ends,  so  that  shipments  can  be 
trucked  through  one  car  into  another  by  bridging  at 
the  car  doors,  and  cars  can  be  placed  and  others  taken 
out  without  disturbing  the  entire  setting. 

Adequate  tracks  for  trucks  are  also  an  important 
part  of  terminal  layouts,  to  provide  for  the  loading  and 
unloading  of  .consignments  by  owners.  This  tonnage 
is  especially  desirable  both  from  an  operating  and 
revenue  standpoint,  as  practically  the  entire  cost  of 
warehouse  labor  is  saved. 

Team  tracks  as  well  as  warehouse  doors  should 
be  easily  accessible  at  all  times  to  the  shippers'  trucks 
and  drays,  and  of  sufficient  capacity  to  take  care  cf 
ihe  business  offered.  Delays  to  patrons'  conveyances 
frequently  result  in  loss  of  future  tonnage. 

In  the  selection  of  rolling  stock  for  freight  service, 
it  is  of  prime  importance  that  both  motive  power  and 
trail  equipment  be  suitable  for  the  service  to  be  per- 
formed, if  most  economical  results  are  to  be  obtained. 
The  number  and  kind  of  locomotives  and  cars  to  be 
used  can  be  determined  only  after  a  careful  study  of 
local  conditions  and  requirements,  and  the  class  of  ton- 
nage available  is  known.  As  a  rule  however,  where  a 
miscellaneous  freight  tonnage,  both  carload  and  less  is 
to  be  had,  and  the  volume  is  sufficient  to  warrant  long 
train  operation,  or  where  there  is  considerable  switch- 
ing service  to  perform,  the  electric  locomotive  is  most 
economical  and  efficient.  In  determining  the  type,  size 
and  capacity  of  a  locomotive  and  its  electrical  equip- 
ment, consideration  must  be  given  to  track  character- 
istics,   curves,    grades,    weight    of    rail,    strength    of 


PIG.   3 — FREIGHT   MOTOR  C.\R  OR  BOX-TYPE  ELECTRIC  LOCOMOTIVE 

bridges,  etc,  as  well  as  to  volume  and  kind  of  tonnage 
to  be  handled;  also  the  maximum  current  which  can 
be  drawn  from  the  substation  should  be  known. 

To  pull  a  trailing  load  of  cars  weighing  a  certain 
number  of  tons,  the  motors  of  a  locomotive  must  be 
capable  of  exerting  a  certain  number  of  pounds  tractive 


476 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  lo 


effort  or  pulling  force  at  the  drive  wheels.  Experience 
has  shown  that  it  requires  a  tractive  effort  of  approxi- 
mately 15  to  25  lb.  per  ton  of  trailing  load  to  start  and 
bring  up  to  speed  a  train  on  a  straight  level  track. 
About  7  lbs.  tractive  effort  per  ton  of  trailing  load  is 
required  to  draw  a  train  at  a  speed  of  25  miles  per 
hour  under  the  same  conditions. 

Motor  capacity  or  output  is  largely  a  matter  of 
temperatures.  A  relatively  small  motor  can  exert  a 
comparatively  enormous  tractive  effort  for  an  instant, 
but  the  heat  developed  in  the  windings  would  be  so 
great  that  damage  would  result  if  operated  continuous- 
ly. A  motor  equipment  may  be  large  enough  to  h:\ul 
a  train  at  schedule  speed  over  a  long  stretch  of  level 
track  and  remain  at  a  safe  temperature,  but  if  grades 
or  long  sharp  curves  were  encountered,  the  temperr.- 
ture  of  the  motor  might  rise  to  a  dangerous  degree. 

A  locomotive  must  weigh  enough  so  that  its  ad- 
hesion to  the  rails  will  enable  the  motors  to  exert  their 
normal  pulling  force.  If  the  locomotive  weighs  too 
little,  the  drive  wheels  will  slip  when  an  attempt  is 
made  to  pull  a  load  which  would  otherwise  be  within 
the  capacity  of  the  equipment.  In  view  of  these  facts, 
it  is  apparent  that  the  maximum  pulling  force  of  a 
locomotive  depends  principally  upon  its  weight  and  is 
not  wholly  determined  by  the  power  of  the  motors. 
The  maximum  tractive  effort  or  pulling  force  th^it  it 
is  possible  for  a  locomotive  to  exert  is  equal  to  from 
25  to  35  percent  of  the  weight  on  the  driving  wheels, 
which  is  modified  by  the  condition  of  the  track  and 
the  design  of  the  locomotive.  If  a  locomotive  is  too 
heavy  for  the  capacity  of  its  motors,  the  weight  on  the 
drivers  is  excessive,  and  the  motors  will  be  overloaded 
before  the  drivers  will  slip.  However,  in  general,  it 
the  weight  of  a  locomotive  is  properly  proportioned  m 
relation  to  the  power  of  the  motors  and  the  service  re- 
quirements, the  drive  wheels  will  slip  if  an  eft'ort  is 
made  to  draw  an  excessive  load,  and  no  harm  will  re- 
sult. 

The  proper  electrical  equipment  for  a  freight  mot- 
or car  or  box  car  type  of  locomotive  is  determined  in 
the  same  way.  This  type  of  car  is  especially  suitable 
for  handling  merchandise  or  trains  of  from  three  to 
six  trailers,  as  it  can  be  used  for  single  unit  operation 
as  well  as  for  hauling  trains,  and  at  the  same  time  car- 
ry revenue  producing  tonnage.  Where  business  con- 
sists principally  of  less  than  carload  freight  or  light 
carload  commodities,  the  motor  freight  car  will  proba- 
bly best  meet  the  requirements.  For  through  service 
between  terminals  or  lai'ge  shipping  centers,  a  heavy 
motor  car  not  less  than  40  ft.  in  length  and  60000  ib. 
capacity,  capable  of  hauling  three  to  five  trailers,  will 
usually  be  found  most  economical,  while  for  service  re- 
quiring frequent  stops,  a  lighter  type  of  motor  car  will 
give  best  results. 


To  give  most  satisfactory  and  economical  service, 
locomotives  or  motor  freight  cars  should  be  equipped 
with  slow-speed  field-control  motors,  and  helical  gears 
with  maximum  gear  ratio.  It  is  neither  necessary  nor 
desirable  that  freight  trains  be  moved  at  a  speed  ex- 
ceeding 25  miles  per  hour,  and  as  a  general  rule  there 
is  nothing  gained  by  running  faster.  The  gain  in 
revenue  and  economy  of  operation  from  heavier  ton-_ 
nage  handled  in  slower  trains  will  quickly  offset  the 
cost  of  providing  sufficient  and  adequate  meeting  and 
passing  tracks. 

All  freight  rolling  stock,  including  locomotives, 
motor  cars  and  trail  cars  should  be  equipped  with 
couplers  and  air  brake  rigging  suitable  for  train  serv- 
ice, to  permit  of  train  operation  and  the  handling  of 
steam  road  equipment  in  interchange  or  switching 
movements.  Methods  of  loading,  dispatching  and 
scheduling  freight  trains  all  have  an  important  bearing 
on  final  net  results  of  freight  handling.  Studies  of  op- 
erating methods  on  electric  lines  have  in  some  cases 
developed  the  fact  that  while  the  net  financial  results 
covering  the  entire  service  for  a  stated  period  have 
been  very  satisfactory,  still  better  net  revenues  could 
be  obtained  by  changes  in  methods  of  dispatching,  load- 
ing of  cars,  longer  train  operation,  or  the  use  of  more 
modern  equipment,  and  this  without  in  any  way  im- 
pairing the  value  of  the  service  to  the  shipper. 

There  are  today,  a  number  of  examples  of  suc- 
cessful freight  operation  among  the  electric  interurban 
lines  of  this  countrj'.  The  average  ratio  of  operating 
expense  to  gross  freight  revenue,  where  results  have 
been  studied  and  economies  effected  through  proper 
supervision,  is  from  70  to  75  percent.  This  expense  in- 
cludes a  proportionate  share  of  the  cost  of  maintenance 
of  roadway,  track,  overhead  lines,  buildings,  power 
generation  and  distribution,  superintendence,  and  any 
other  facilities  used  jointly  with  other  branches  of 
service,  and  all  expense  of  maintenance,  operation 
labor,  etc.  properly  chargeable  to  freight  oneration  only. 
An  efficient,  properly  directed  traffic  department 
is  indispensable  to  successful  freight  operation.  This 
department  is  in  position  to  know  the  needs  of  patrons, 
their  individual  peculiarities  and  requirements,  and  is 
responsible  for  increasing  or  losing  tonnage,  and  should 
therefore  be  consulted  and  have  equal  voice  with  the 
transportation  department  in  deciding  upon  service  to 
be  rendered,  scheduling  of  trains,  distribution  of  equip- 
ment, and  the  settlement  of  all  questions  which  may 
arise  effecting  transportation  relations  with  the  public. 
This  department  is  also  entrusted  with  the  burden  of 
securing  new  business,  locating  new  industries  on  the 
line,  co-operating  with  local  civic  bodies  and  associa- 
tions for  mutual  benefit,  compiling  and  publishing 
tariffs,  arranging  joint  through  rates,  divisions  and 
schedules,  and  in  fact  meeting  and  satisfying  the 
public  on  all  matters  connected  with  the  transportation 
of  goods. 


Safsty  Cav  OpOi'ailiu^  llo^nJi:^ 


C.  L.  DOUB 

General  Engineering  Dcpt., 
Wcstinghoiise  Electric  &  Mfg.  Company 


A  STUDY  of  the  operation  of  safety  cars  yields 
a  great  deal  of  very  interesting  and  gratifying 
data.  From  practically  every  viewpoint,  the  car 
has  proven  a  success.  It  has  come  to  occupy  a  dis- 
tinct field  in  the  electric  railway  industry  and  is  sure 
to  be  of  increasing  importance.  It  is  inherently  more 
economical  in  operation  than  the  heavier  double-truck 
or  single-truck  car  which  it  is  supplanting,  but  its 
effect  has  been  more  far-reaching.  The  use  of  the  car 
has  not  only  decreased  the  operating  and  transporta- 
tion expenses,  but  more  frequent  and  more  rapid  serv- 
ice has  been  supplied  the  patrons,  resulting  in  a  con- 
sistent increase  in  gross  revenue.  The  degree  to 
which  these  advantages  occur  may  readily  be  seen 
from  a  few  simple  charts,  based  on  rece.it 
data  from  representative  operating  com- 
panies. 

PL.\TF0RJM     EXPENSE 

The   primary   reduction    in   expense    re- 
sults from  one-man  operation.     The  elimiii- 
ation  of  one  man  from  the  crew  has  nearly 
halved  the   platform   expense.      In   order   to 
give  the  car  operator  a  share  in  the  advant- 
ages of  safety  car  operation,  it  has  been  the 
general  practice  to  increase  his  rate  of  pay 
approximately   ten   percent   above  that   of  a 
platform  man  on  two-man  cars.     Compensa- 
tion for  the  smaller  seating  capacity  of  the 
light-weight   car   has   been   made   by   an    in- 
increase  in  the   number  of  .cars  on    the   line. 
There  has  thus  been  an  increase  in  the  total 
number  of    car-hours    of    operation,    which 
partly    offsets    the    reduction    of    man-hours 
accomplished  by  using  one  man  per  car  .in- 
stead of  two.     In  many  cases  ,the  increase  in  schedule 
speed  has  allowed  more  trips  per  car  and  a  decrease  in 
headways  without  a  proportional  increase  in  the  num- 
ber  of    car-hours.     The    increased    revenues    resulting 
from   the    increased    operation    have    in    general    fully 
justified  the  increase  in  car-hours.     In  general,  there 
has  been  a  decrease  in   total  platform   expense  of  25 
percent,  which  takes  into  consideration  the  increase  in 
car  mileage  and  increase  in  schedule  speed.     A  sav.ing 
per  car-hour  in  platform  labor  of  45  percent,  as  shown 
m  Fig.  I,  would  result  if  safety  cars  merely  duplicated 
the  previous  service. 

MAINTENANCE   EXPENSES 

As  a  result  of  the  decreased  weight,  there  is  a  cor- 
responding decrease  in  equipment  maintenance  ex- 
pense. The  standardization  of  apparatus  and  the 
ease  of  overhauling  contribute  also  to  the  reduction  in 


the  expense  for  repairs.  A  single  truck  is  obviously 
less  expensive  to  maintain  than  the  two  trucks  of  a 
double  truck  car.  However,  the  comparison  is  not 
confined  to  double-truck  cars.  Improvements  in  the 
truck  and  car  body  design  have  largely  eliminated  the 
galloping  and  rocking  prevalent  with  the  older  types 
of  single-truck  cars.  A  considerable  decrease  in  the 
wear  and  tear  on  the  car  and  equipment  results  in  a 
reduction  of  maintenance  expenses,  in  addition  to  sav- 
ings attributable  to  decreased  weights.  Data  supplied 
by  companies  which  keep  segregated  costs  for  safety 
cars  and  two-man  cars  show  approximately  a  40  per- 
cent saving.  A  reasonable  cost  for  maintenance  of 
safety  cars  under  present  labor  and  market  conditions 


—120 

— 

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FIG.    I — OI'ER.\TING    RESULTS    OF    S.\FETY    CARS    AND    TWO-MAN    CARS 

is   found   to  be  approximately  2.0  cents  per  car-mile, 
with  average  operating  conditions. 

Track  repairs  attributable  to  safety  cars  are  ap- 
preciably less  than  for  the  older  types  of  cars,  on  ac- 
count of  the  lighter  weight  of  the  rolling  stock.  It  is 
difficult  to  obtain  accurate  records,  of  the  savings  re- 
sulting, because  the  costs  extend  over  a  long  period  of 
time  and,  in  most  cases,  various  types  of  cars  operate 
over  the  same  tracks.  It  is  estimated  that  safety  cars 
effect  a  saving  of  30  to  40  percent  in  this  item. 

ENERGY    CONSUMPTION 

Many  tests  have  been  made  to  show  the  savings 
in  energy'  consumption  resulting  from  the  use  of  the 
safety  car.  Results  have  been  expressed  to  include 
energy  for  running  the  car,  total  consumption  at  car, 
including  energy  for  lighting,  heating  and  auxiliaries, 
and  line   losses    from    car   to   substation.     The   energy 


478 


THE   ELECTRIC  JOURNAL 


consumption  is  roughly  proportional  lo  the  total  weight 
of  car  and  load.  In  some  cases,  where  heavy  cars 
were  replaced,  the  safety  car  consumption  is  as  low  as 
one-third  that  of  the  equipment  supplanted.  On  the 
average,  the  saving  amounts  to  approxim.tely  50  per- 
cent of  the  original  consumption  (C,  Fig  i).  The 
■sctual    power    consumption    will,    of    cour.so,    depend 


s 

S-17S 

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FIG.  2 — EFFECT  OF  CAR  MILE.\GE  UPON  REVT.NUE 

largely  upon  the  class  of  the  service  and  the  severity 
of  grades.  The  theoretical  power  consumption  with 
ordinary  service  on  a  level  route  is  approximately  one 
kilowatt-hour  per  car-mile.  For  all  classes  of  actual 
service,  an  average  value  of  1.25  kw-hr.  per  car-mile 
i?  reasonable  for  power  consumption  at  the  car.  In- 
cluding power  for  light,  heat,  and  auxiliaries,  the  total 
power  consumption  at  the  car  will  be  approximately 
1.75  kw-hr  per  car-mile.  The  average  distribution 
losses  will  be  10  to  15  percent  of  the  power  used  by 
safety  car.  In  addition  to  the  saving  in  operat- 
ing expenses,  safety  car  operation  decreases  the  load 
on  the  power  system.  This  may  be  very  important 
when  generating  and  converting  machinery  are  over- 
loaded. The  lower  power  demand  reduces  the  voltage 
drop  in  the  distribution  system,  increasing  the  average 
voltage  at  the  car  and  at  the  same  time  improving  the 
efficiency  of  distribution.  The  necessity  of  installing 
additional  feeder  copper  may  often  be  avoided  by  the 
initiation  of  safety  car  operation. 

GENERAL   EXPENSES 

Ordinarily  there  will  not  be  much  reduction  in 
total  general  and  overhead  expenses.  However,  in 
view  of  the  increased  service  and  increased  traffic  at- 
tending safety  car  operation,  the  unit  charge  is  reduced. 
On  the  basis  of  the  increased  car  mile- 
age of  60  percent  as  given  in  the  dis- 
cussion of  gross  revenue,  the  general 
expense  per  car  mile  is  reduced  ap- 
proximately 40  percent  {D,  Fig.  i). 

Depreciation     and     fixed     charges 
vary  in  proportion  to  installation  costs. 
Original    costs    in    turn    vary    approxi- 
mately as  the  weight  of  equipment.    Al- 
though the  cost  per  safety  car  is  much 
less  than  that  of  the  two-man  cars  replaced,  more  cars 
are  generally  provided  to  supply  the  increased  service. 
The  net  effect  is  that  the  total  fixed  charges  and  depre- 
ciation will  be  reduced  approximately  40  percent. 

TOTAL   OPERATING    COSTS 


Vol.  XVni,  No.  10 

within  wide  limits.  Similarly,  the  total  savings  result- 
ing from  any  change  in  methods  of  operation  will  vary 
considerably.  Many  operators  have  been  prompt  in 
taking  full  advantages  of  the  possibilities  of  the  safety 
car.  Figures  submitted  for  gross  savings  per  year  and 
also  records  of  segregated  costs  show  that  an  average 
saving  of  40  percent  of  the  total  operating  costs  on  a 
car-mile  basis  {F,  Fig.  i)  is  conservative.  One 
operator  in  the  East  recently  reported  a  saving 
in  platform  labor  alone  equivalent  to  more  than 
$2QOO  per  car  per  year.  While  this  is  undoubtedly 
the  largest  single  item  of  savings,  it  is  estimated  that 
on  this  property  there  will  be  an  additional  sav^mg  of 
$2000  in  other  operating  expenses.  The  present  cost 
of  a  standard  safety  car  is  approximately  $6500. 
After  allowing  for  fixed  charges,  it  is  readily  seen  that 
these  savings  will  retire  the  original  investment  within 
a  few  years,  after  which  the  savings  will  apply  as  a 
net  gain. 

PASSENGER  REVENUES  INCREASED 

Not  only  have  substantial  savings  been  shown  in 
operating  expenses,  but  safety  cars  have  consistently 
stimulated  traffic,  even  under  adverse  conditions.  The 
increase  in  riding  is  chiefly  a  result  of  the  decreased 
headways  supplied  by  safety  cars.  The  increase  in 
number  of  revenue  passengers  hauled  has  been  found 
to  be  almost  a  direct  function  of  the  increase  in  serv- 
ice supplied,  up  to  certain  limits.  .Mthough  a  few  rail- 
way companies  have  instituted  safety  car  service  upon 
a  car-for-car  basis,  most  of  the  operators  have  in- 
creased car-mileage  from  25  percent  to  100  percent. 
The  average  increase  has  been  probably  60  percent.  It 
has  rarely  been  found  profitable  to  increase  service 
teyond  100  percent.  Although  one  of  the  principal 
factors  in  increasing  riding  has  been  the  securing  of 
passengers  who  would  walk  a  relatively  short  distance 
rather  than  wait  for  a  car,  no  doubt  the  newness  and 
attractiveness  of  the  car  have  contributed  a  consider- 
able share.  The  service  has  been  improved  also  by  in- 
creases of  15  to  20  percent  in  schedule  speed.  The 
easy  riding  characteristics  of  the  car,  as  compared  with 
older  types  of  single-truck  cars,  have  played  an  impor- 


On  properties  of  different  size  and  with  different 
conditions  of  operation,  total  operating  costs  will  vary 


INCREASE  IN   REVENUE  RESULTING   FROM    SAFETY   CAR    OPERATION 

tant  part  by  holding  the  passengers  once  obtained. 

The  seating  capacity  of  the  standard  double  end 
safety  car  is  32,  and  that  of  the  ordinary  two-man  cars 
replaced  is  from  30  to  50.  While  the  capacity  of  each 
car  substituted  is  less,  the  increased  car-mileage  gives 
r.  seat-mileage  as  great  as  or  greater  than  before.  It 
is  estimated  that  on  the  average,  the  60  percent  increase 


October,  1921 


THE  ELECTRIC  JOURNAL 


479 


in  service  provides  15  to  25  percent  increase  in  seat- 
mileage.  The  seat-mileage  is  not  only  increased,  but 
is  better  distributed  so  as  to  better  serve  the  needs  of 
the  public.  The  increase  in  the  number  of  units  pro- 
vides more  flexibility  of  operation. 

The  increase  in  revenue  is  of  course  directly  pro- 
portional to  the  increase  in  paid  passengers.  Revenue 
increases  up  to  75  percent  have  been  reported  for  the 
lines  on  which  the  safety  car  has  supplanted  the  two- 
man  car.  The  average  increase  in  gross  receipts,  cor- 
responding to  the  increase  in  service  of  60  percent,  is 
estimated  from  a  number  of  published  reports  to  be 
40  percent.  Both  the  increase  in  revenues  and  the  de- 
crease in  operating  expenses  act  to  decrease  the  operat- 
ing ratio. 

The  effect  of  increased  car-mileage  upon  the 
passenger  revenues  is  illustrated  by  the  records  for 
one  of  the  lines  in  Bridgeport,  Conn.,  where  safety 
cars  were  adopted  in  May,  1918.  The  curves  in  Fig. 
2   are   based   upon   these   records   and   are   of   especial 


FIG.  4 — SAI'I   1  i('E  FOR  HEAVY    I  I;  \  I- 1  H      \  ^   W  I  I  I.    \ -,    I  h  ,  I  IT 

value  in  depicting  actual  results.  The  number  of 
passengers,  as  indicated  by  the  gross  revenue,  varied 
almost  directly  as  the  car-mileage  of  the  line,  and  the 
effects  were  obtained  immediately.  Corresponding  to 
the  maximum  increase  of  service  of  80  percent,  there 
was  an  increase  in  revenue  of  from  60  percent  to  70 
percent. 

ACCIDENTS 

The  appropriateness  of  the  name  Safely  is  brought 
out  by  a  study  of  accident  records.  It  had  been  sug- 
gested that  there  would  be  more  probability  of  collision 
with  other  vehicles,  on  account  of  the  higher  rates  of 
acceleration  generally  used  and  because  the  motorman's 
attention  would  be  at  least  partially  distracted  from 
operation  of  the  car  by  collecting  fares  and  making 
change.  However,  this  has  not  been  found  to  be  the 
case.  The  number  of  accidents  has  in  most  cases  been 
reduced  approximately  one-half.  Several  operators 
report  that  a  large  proportion  of  the  safety  car  acci- 
dents are  trivial.  The  safety  devices  have  practically 
eliminated  door  and  step  accidents  on  many  lines.  A 
reduction  of  accidents  is  important  from  a  financial 
point  of  view,  for  the  costs  of  accidents  have  been  cor- 


respondingh-  reduced.  The  imporlai;ce  of  accidents  is 
emphasized  by  a  recently  published  estimate  that  ap- 
proximately 4.6  percent  of  the  gross  revenue  of  elec- 
tric railways  is  paid  out  to  satisfy  accident  claims. 

RESULTS  WITH  SAFETY  CARS  IN  SIJARON 

Some  very  interesting  data*  showing  the  effect  of 
safety  cars  in  stimulating  traffic  were  obtained  by  the 
Pennsylvania-Ohio  Electric  Co.  The  curves  in  ¥\g.  3 
are  derived  from  this  data,  showing  the  passenger 
revenue  per  month  on  one  of  the  safety  car  lines  in 
Sharon,  Pa.,  one  year  before  and  one  year  after  the 
introduction  of  safety  cars,  and  the  variation  of 
passenger  revenue  on  one  of  the  two-man  car  lines  in 
Sharon  for  the  same  period.  The  averages  of  revenues 
for  April,  May,  and  June,  1919,  are  taken  as  100  in 
each  case.  It  will  be  seen  that  the  traffic  had  the 
same  general  characteristics  for  the  two  lines  during 
the  first  half  of  the  period  taken,  when  two-man  cars 
were  used  on  both  lines.  The  same  seasonal  varia- 
tions occur,  indicating  that  the  traffic  conditions  on  the 
two  lines  are  comparable.  Safety  cars  were  installed  on 
line  A  in  April,  1921.  From  this  time,  line  A  shows  a 
very  decided  increase  in  revenue.  It  is  notable  that 
during  the  same  time  the  revenues  on  line  B  show  a 
decrease  in  comparison  with  the  preceding  year.  This 
decrease  has  been  attributed  to  the  industrial  depres- 
sion prevailing,  which  would  be  expected  to  affedt  both 
lines  in  a  similar  way.  An  increase  in  fares  in  Decem- 
ber, 1920,  is  responsible  for  a  rise  in  both  curves.  The 
decrease  in  revenue  following  the  change  in  fares  cor- 
responds to  the  seasonal  variation  of  the  preceding 
year.  The  number  of  paid  passengers  on  line  A  was 
approximately  45  percent  greater  for  the  year  follow- 
ing safety  car  operation  than  for  the  year  preceding,  in 
spite  of  the  industrial  depression  and  the  higher  fare 
existing  during  part  of  the  period.  The  actual  increase 
in  passenger  revenue,  taking  account  of  the  higher 
fare,  was  approximately  60  percent. 

CAR   OF  PRESENT  DESIGN   SUCCESSFUL 

There  has  been  no  pronounced  case  of  failure  of 
the  safety  car  to  disparage  the  many  favorable  reports. 
Although  some  opposition  from  trainmen  has  been 
anticipated,  the  service  has  in  practically  all  cases  been 
instituted  in  such  a  way  that  the  occasional  objections 
were  soon  overcome.  There  have  also  been  some  in- 
stances of  opposition  by  the  patrons,  but  these  l.ave 
been  removed  after  a  trial  of  the  safety  car.  More- 
over, the  results  obtained  have  not  usually  been  due  to 
favorable  conditions  of  operation,  for  the  cars  have 
been  adopted  for  many  lines  which  were  showing  finan- 
cial losses  or  which  were  handicapped  by  other  diffi- 
culties. At  the  present  time  nearly  5000  standard 
safety  cars  are  being  used  in  cities  of  all  sizes,  and 
their  field  of  usefulness  is  increasing.  Occasional 
suggestions  are  made  for  various  modifications  of  the 


♦Given  in  a  paper  by  Mr.  C.  D.  Smith,  General  Superintend- 
ent. The  Pennsylvania — Ohio  Electric  Company,  before  the 
Pennsylvania  Street  Railway  Association,  June,  IQ2I. 


48o 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII.  No.  lo 


design  of  the  standard  car,  but  it  is  probably  the  more 
common  opinion  that  tlie  standard  should  be  continued 
with  substantially  the  same  design.  It  is  especially  im- 
portant that  no  change  should  be  made  that  involves 
any  considerable  increase  in  weight,  for  the  light 
weight  has  been  one  of  the  principal  factors  in  effect- 
ing the  econoni}''  of  operation. 


While  no  attempt  is  made  to  present  the  safety  car 
as  the  cure-all  for  every  street  railway  ill,  and  it  is  not 
claimed  to  be  the  most  suitable  car  for  all  types  of 
lines,  there  are  many  conditions  for  which  it  is  best 
suited.  As  it  has  done  repeatedly  in  the  last  five 
years,  it  will  continue  to  contribute  the  difference  be- 
tween profit  and  loss  for  many  street  railway  lines. 


F.  G.  HICKLING 

Railway  Division, 
Westinghousc  Electric  &  Mfg.  Company 


M 


OST  of  us  recall  how  crippled  and  sick  the 
street  railways  were  during  the  severe 
winter  of  1917-18,  when  incessant  cold  snaps 
were  frequently  broken  by  short  warm  spells  with 
heavy  snows.  The  streets  were  either  a  sheet  of  ice 
or  a  mass  of  slush  and  water,  and  the  automobile,  so 
frequently  used  by  the  business  man,  found  a  haven 
of  rest  in  the  garage.  The  street  railway  companies, 
in  many  cities,  were  not  only  called  upon  to  handle 
their  normal  volume  of  passengers,  but  had  these  addi- 
tional riders  to  carry  as  well.  The  street  car  tracks, 
were  kept  cleared  of  snow  by  the  street  railway  com- 
pany, but  frequently  were  several  inches  lower  than  the 
accumulated  snow  in  the  usual  vehicular  paths,  so  that 
the  car  tracks  were  the  temporarj'  beds  of  small 
streams  and  pools,  through  which  the  cars  had  to  be 
operated.  Thus  the  motors  had  their  windings  soaked 
with  water  and  dirt. 

Due  to  the  unusually  long  siege  of  operation  under 
these  conditions,  the  equipment  failures  increased  to 
a  point  where  the  railway  shops  could  not  keep  up 
with  the  repairs,  and  the  manufacturers  of  railway 
equipment,  were  also  taxed  to  their  utmost.  As  the 
result  of  this  condition,  about  twenty  railway  operat- 
ing men,  who  were  in  charge  of  the  operation  and 
maintenance  of  railway  equipment  throughout  the  cen- 
tral and  eastern  states,  met  at  the  East  Pittsburgh 
Works  of  the  Westinghousc  Compariy  for  a  consulta- 
tion with  the  Company's  designing  engineers. 

After  this  meeting,  it  was  felt  by  the  railway  op- 
erating men  in  attendance,  that  so  much  good  had  re- 
sulted from  an  exchange  of  ideas,  that  they  resolved 
to  form  a  permanent  gathering.  The  result  is  the 
Association  of  Electric  Railway  Men,  which  includes 
the  master  mechanics  and  equipment  men  of  about 
forty  railway  companies  in  Ohio,  Pennsylvania  and 
West  Virginia,  with  a  membership  roll  of  seventy  men. 
This  Association  holds  a  meeting  in  the  spring  and 
fall  of  each  year.  About  thirty-five  to  fifty  men  are 
usually  present  at  each  meeting.     These  men  sit  around 


a  large  table  and  discuss  the  operating  and  mainten- 
ance problems  submitted  by  the  members  themselves 
in  the  form  of  a  questionaire  (each  member  being 
limited  to  three  questions)  to  the  secretary,  who  lists 
them  and  redistributes  a  complete  questionaire  to  each 
member  from  two  to  three  weeks  in  advance  of  the 
date  of  the  meeting. 

In  this  manner  each  representative  sends  in  ques- 
tions which  are  of  paramount  issue  with  him,  and  he 
knows  that  his  questions  will  come  up  for  discussion. 
He  will  also  have  a  list  of  the  other  fellows'  problems 
and  will  get  the  benefit  of  these  discussions.  He  also 
knows  that  he  must  come  prepared  to  discuss  any  of 
the  questions  listed  on  the  questionaire.  The  manner 
of  conducting  the  meeting  makes  it  necessary  for  the 
secretary,  to  know  each  member  personally,  and  all 
members  are  subject  to  call  for  discussion. 

At  times  the  members  desire  to  have  a  particular 
problem  discussed  by  representatives  of  some  of  the 
manufacturing  companies,  in  which  case,  invitations 
are  extended  to  the  manufacturers  to  have  a  represen- 
tative present.  Experts  on  air  brake  equipment, 
railway  motor  maintenance,  arc  welding,  etc.  have 
given  interesting  talks  and  the  discussions  on  these 
subjects  are  of  great  value. 

The  secretary  keeps  accurate  notes  and  the  com- 
plete minutes  of  the  meeting  are  written  up  and  a  copy 
sent  to  each  member.  The  members  can  refer  to 
these  minutes  and  can  also  pass  them  on  to  the  "boss" 
to  let  him  know  what  was  accomplished  at  the  meet- 
ing. The  meeting  is  always  closed  in  time  for  a  visit 
to  the  shops  of  the  local  railway  company.  This  visit 
usually  results  in  a  few  new  ideas  being  picked  up  by 
the  members  and  gives  them  an  opportunity  to  com- 
pare the  shop  methods  in  force  with  their  own. 

From  the  nature  of  such  meetings,  it  is  obvious 
that  every  member  present  is  sure  to  gain  much  valu- 
able information.  The  equipment  man  is  always  con- 
cerned in  maintenance  costs,  as  his  job  depends  on  a 
good  showing,  and  if  he  can  pick  up  one  or  two  new 


October,  1921 


THE  ELECTRIC  JOURNAL 


ideas  at  each  meeting,  the  time  and  expense  of  attend- 
ing the  meeting  is  amply  repaid,  both  to  him  and  his 
company.  Attendance  at  such  meetings  puts  him  in 
touch  with  others,  so  that  future  correspondence  de- 
velops. In  time  of  stress,  such  as  a  repetition  of  the 
troubles  of  the  winter  of  1917-18,  he  may  be  able  to 
borrow  men  and  supplies,  if  wanted  in  an  emergency 
to  avoid  a  tie-up  of  his  equipment. 

From  the  above  it  will  be  seen  that  this  Associa- 
tion is  conducted  somewhat  differently  from  the  usual 
meetings  or  conventions.  With  the  "round  table"  dis- 
cussion, all  members  soon  become  acquainted  with  one 
another,  they  speak  in  their  own  terms,  and  give  others 
the  benefit  of  their  experience. 

The  railway  companies  who  send  their  men  to 
these  meetings,  benefit  by  the  knowledge  gained  by 
their  men.  The  men  themselves  often  get  out  of  a  rut, 
deepened  through  never  having  come  in  contact  with 
others  doing  similar  work  and  maintaining  similar 
equipment.  The  manufacturer  benefits  by  knowing 
whether  his  apparatus  is  looked  upon  with  favor  in  the 
field,  whether  it  is  made  accessible  for  ready  inspection 
and  repairs,  and  whether  the  parts  are  strong  enough 


to  resist  the  strains  upon  them,  and  if  the  maintenance 
cost  is  excessive. 

The  fame  of  the  Association  of  Electric  Railway 
Men  has  spread,  so  that  the  present  organizations  are 
beginning  to  realize  the  necessity  of  having  equipment 
men  represented  in  this  association.  This  is  empha- 
sized by  the  Central  Electric  Railway  Association 
forming  under  their  body,  an  engineering  council  and 
four  local  engineering  sections,  namely ;  the  Akron 
Section,  the  Toledo  Section,  the  Dayton  Section  and 
the  Indianapolis  Section. 

Any  engineering  organization  conducted  along 
plans  similar  to  the  manner  of  conducting  the  meetings 
of  the  Association  of  Electric  Railway  Men,  should 
be  successful,  and  other  similar  associations  will,  of 
necessity,  form  a  clearing  house,  where  the  members 
can  recite  their  problems  and  get  together  on  a  sound 
basis  to  correct  them  in  the  future. 

The  success  of  meetings  of  this  kind  depends  on 
keeping  the  sections  limited  in  size,  so  that  the  "round 
table"  conference  can  be  maintained  and  the  distance 
to  be  travelled  reduced  so  as  not  to  keep  the  operating 
men  away  from  their  work  for  more  than  a  day  or 
two  at  a  time. 


Railway  Motoi's 


J.   K.  STOTZ 

Motor  Engineering  Dept.. 
Westinghouse  Electric  &  Mfg.  Company 


THE  modern  commutating-pole  type  railway  mo- 
tor has  inherently  good  commutation  in  practi- 
cally every  case.  Nevertheless,  as  every  opera- 
tor realizes,  there  may  be  more  or  less  flashing  on  the 
average  motor  in  service.  Usually  this  is  not  bad 
enough  to  do  any  particular  damage  or  cause  any  real 
trouble  but  may,  at  times,  reach  serious  prof)ortions 
under  unusual  conditions.  A  survey  of  some  of  the 
causes  of  flashing  may  give  a  clue  as  ot  the  cause  of 
trouble  on  a  particular  road.  A  flash  may  be  caused  \a 
a  number  of  ways: — 

o — Interruption  and  Re-establishment  of  Powers 
Supply  by  jumping  of  trolley,  section  breaks,  etc.,  while 
the  motor  is  running.  All  modern  railway  motors 
stand  power  interruptions  on  the  test  floor  at  all  speeds 
and  at  voltages  far  in  excess  of  practical  operating  con- 
dition. For  this  reason  trouble  from  such  causes  can 
usually  be  traced  to  some  very  unusual  operating  condi- 
tion. 

h — Bucking — This  method  of  stopping  a  car 
should  be  resorted  to  only  in  an  emergency,  for  it  pro- 
duces severe  mechanical  strains  on  equipment  as  well 
as  being  a  frequent  cause  of  flashing.     There  are  some 


possibilities  in  control  changes  to  help  the  motors  when 
bucking  is  resorted  to,  but  the  real  remedy  is  to  edu- 
cate the  motorman  so  that  he  will  not  buck  the  motors 
unless  there  is  no  other  way  of  stopping  the  car. 

c — Salt — In  the  winter  time,  when  switch  points 
are  sprinkled  with  salt,  there  is  a  possibility  of  salt  wa- 
ter entering  the  motor,  getting  on  the  commutator  and 
causing  flashing.  This  is  not  apt  to  be  a  very  frequent 
cause  of  trouble  and  can  be  remedied  by  proper  atten- 
tion to  motor  covers. 

d — Incorrect  Brush  Spacing — The  effect  of  incor- 
rect brush  spacing  is  to  cause  more  or  less  severe  spark- 
ing, depending  upon  how  far  ofif  neutral  the  brushes  are 
set.  If  the  sparking  is  severe  it  may  cause  flashing  and 
at  least  it  will  prevent  the  commutator  from  becoming 
properly  polished.  The  modern  railway  motor  is  not 
apt  to  give  trouble  from  this  source,  since  the  brush- 
holder  seats  are  fixed  and  the  motor  is  checked  for 
neutral  before  it  leaves  the  factory.  Many  of  the  old- 
er motors  do  not  have  fixed  seats  for  the  brushholders, 
so  that  in  case  of  trouble  from  flashing  and  poor  com- 
mutation, the  brush  locations  should  be  checked. 

e — Jumping  of  the  Carbons — If  the  brush  leaves 


482 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  10 


the  commutator  surface  while  the  power  is  on,  it  draws 
an  arc  and  generates  a  cloud  of  conducting  vapor,  the 
amount  of  which  depends  upon  the  distance  the  carbon 
is  raised,  the  length  of  time  it  is  raised,  the  current 
flowing,  etc.  If  much  conducting  gas  is  generated  it 
may  be  carried  by  the  commutator,  the  ventilating  air 
and  stray  magnetic  fields  to  a  point  where  it  reaches 
ground  or  the  other  brushholders  and  a  flash  results. 

The  jumping  may  be  very  slight  and  of  short  du- 
ration, in  which  case  it  will  result  only  in  slight  spitting 
and  sometimes  roughening  and  blackening  of  the  com- 
mutator, causing  excessive  brush  wear.  Again  the 
brush  may  stick  and  the  motor  commutate  through  the 
arc  drawn.  This  may  continue  for  some  time  without 
flashing  over  but  of  course  burns  the  commutator  and 
brush  rapidly.  In  between  lie  all  degrees  of  jumping. 
It  is  unnecessary  to  go  into  any  detail  as  to  the  effects 
of  the  resultant  flashing.  Every  operator  knows 
through  sad  experience,  the  evidence  of  grounded 
brushholders,  burnt  wiring  around  frame  and  field 
coils,  grounded  armatures,  bulged  field  coils,  etc. 
Some  of  the  causes  for  this  jumping  of  the  brushes 
may  not  be  so  evident. 

If  we  assume  that  the  commutator  surface  is  a 
true  cylinder,  concentric  with  the  shaft  of  the  motor, 
and  that  the  brushholders  are  fixed  in  position  relative 
to  the  commutator,  then  the  brushes  will  remain  in 
contact  with  it  at  all  speeds.  If  the  commutator  is 
not  concentric  with  the  shaft  or  if  it  is  slightly  out  of 
true,  the  brushes  will  remain  in  contact  with  the  com- 
mutator at  slow  speeds,  but  as  the  speed  increases  it 
will  finally  reach  a  point  where  the  brushes  will  leave 
the  commutator  surface  for  part  of  a  revolution. 
That  is  the  commutator  surface  will  drop  away  from 
the  true  circle  faster  than  the  brush  can  follow  it 
This  speed  depends  upon  the  inertia  of  the  brush  and 
spring  mechanism,  the  friction  of  the  brush  in  the  box 
and  the  spring  pressure.  An  occasional  high  bar  or 
high  mica,  or  a  flat  spot,  will  produce  the  same  result, 
but  usually  at  a  lower  speed  than  w-here  the  change 
in  the  rotating  surface  is  gradual. 

Such  variations  in  the  true  surface  of  the  commu- 
tator are  frequently  met  in  service.  They  may  be  due 
to  a  number  of  causes,  such  as  loose  V-rings,  varia- 
tions in  individual  bars,  improper  curing,  worn  com- 
mutators, loose  bars,  etc.  Due  to  the  burning  that  re- 
sults when  tlie  brush  leaves  the  commutator,  any  ir- 
regularity in  the  commutator  surface  tends  to  become 
worse.  The  remedy  for  such  a  condition  is  to  tighten 
the  V-rings  properly,  take  a  light  turn  off  the  commu- 
tator to  true  it  up,  and  undercut  the  mica  if  necessary. 
When  this  is  done  it  will  usually  be  found  that  a  com- 
mutator that  has  been  blackened  and  dirty  will  take  a 
good  polish  and  assume  that  chocolate  glaze  that  is  so 
desirable. 

Another  way  in  which  the  brushes  may  be  made 
to  leave  the  commutator  is  for  the  commutator  itself 


to  move  up  or  down  with  relation  to  the  frame.  When 
the  armature  bearings  are  worn  this  will  occur  every 
time  power  is  applied  or  shut  off,  due  to  the  variation 
in  magnetic  pull  and  the  change  in  direction  of  the  mo- 
tor torque,  or  whenever  the  car  goes  over  any  sort  of 
a  bump.  Worn  bearings  and  gears,  loose  bolts,  poorly 
adjusted  axle  collars,  loose  or  tight  brakes,  are  respon- 
sible for  much  trouble  of  this  nature. 

Under  conditions  of  loose  bolts  and  worn  bearings 
the  ability  of  the  carbon  to  follow  the  commutator  can 
be  improved  by  raising  the  spring  tension.  Even  this 
will  not  cure  the  trouble  when  conditions  are  bad,  and 
the  general  condition  of  the  entire  equipment  must  be 
improved  before  satisfactory  operation  will  be  ob- 
tained. Not  only  will  proper  maintenance  help  flash- 
ing conditions  but  it  will  improve  the  general  opera- 
tion of  the  motors. 

Sometimes  trouble  is  experienced  from  flashing 
even  though  the  motors  and  equipment  are  well  main- 
tained. The  rails  and  roadbed  may  be  responsible  in 
these  cases.  Poorly  maintained  roadbed,  with  loose 
fish  plates,  bad  joints,  etc,,  will  jar  the  entire  motor  so 
much  that  it  may  flash  due  to  jumping  carbons.  Oc- 
casionally a  very  rigid  roadbed  will  cause  trouble  due 
to  vibrations  set  up  in  the  equipment,  and  sometimes 
corrugated  rail  is  the  cause  of  the  trouble. 

In  attempting  to  produce  motors  that  will  stand 
these  conditions,  the  designers  have  been  working  to- 
ward spring  mechanisms  of  lighter  weight  and  fewer 
moving  parts  and  sliding  surfaces  in  order  to  reduce 
inertia  and  friction,  thereby  allowing  the  carbon  to  fol- 
low the  movements  of  the  commutator  more  closely, 
and  thus  reduce  the  length  of  time  the  brush  is  off  the 
commutatator  if  not  eliminate  it  altogether. 

The  operator  can  help  himself  in  this  respect  by 
keeping  the  brushholders  clean  and  their  harness  oiled, 
so  that  there  is  no  sticking  or  binding  at  any  point  in 
their  travel.  Carbons  should  be  replaced  before  they 
are  worn  so  short  that  the  spring  cannot  exert  any  pres- 
sure on  them.  Brush  tension  should  be  checked 
periodically  and  kept  to  the  proper  value  to  give  the 
best  results. 

If  the  brushholders,  commutator  and  motors  in 
general  are  in  good  condition  and  flashing  still  occurs, 
higher  brush  tension  should  be  resorted  to.  Values 
as  high  as  10  to  1 1  lbs.  per  sq.  in.  may  be  used  in  some 
cases  with  a  decided  improvement  in  operation.  We 
might  anticipate  greater  brush  wear  as  a  result  of  in- 
creased tension  but  the  experience  of  a  number  of  op- 
erators shows  the  opposite  result  to  be  the  case.  The 
life  of  carbons  is  equal  to  or  greater  than  that  obtained 
with  low  pressure  when  frequent  flashing  occurs.  The 
reason  is  that  the  reduction  in  sparking  and  flashing  as 
a  result  of  the  higher  pressure  materially  reduces  the 
burning  of  the  carbons  and  the  improved  polish  ob- 
tained on  commutator  and  brushes  reduces  the  friction 
and  consequent  mechanical  wear  in  spite  of  the  hifriier 
pressure. 


October,  1921 


THE   ELECTRIC  JOURNAL 


483 


THE 
ELECTRIC 
JOURNAL 


^AIILW^Y  ©FIEMATM^  PATA 


le    purpose    of    this    section    is    to    present 

cepted  practical  metbods  used  by  operating 

companies    throughout    the    country 


-operation  of  all  those  interested  in 
ig  and  maintaining  railway  equipment 
Tited.      Address    R.    O.    D.    Editor. 


OCTOBER 

I92I 


Electric  Welding  as  a  Factor  in  Reclamation 


As  a  matter  of  economy  and  forced  necessity  to  keep  their 
cars  on  the  road,  it  has  always  been  the  practice  of  street  rail- 
way operators  to  repair  in  their  own  shops  certain  worn  and 
broken  parts  of  their  equipment.  However,  the  \'ariety  of  work 
was  limited  on  accoimt  of  the  expense  and  lack  of  facilities. 
Within  the  past  few  years,  the  reclamation  of  railway  equip- 
ment has  broadened  into  quite  a  wide  field  of  application,  largely 
through  the  development  and  practical  application  of  electric 
arc  welding.  This  method  effects  a  great  saving  in  making  such 
repairs,  as  in  many  cases  they  can  be  made  without  dismantling, 
thus  keeping  the  car  in  service,  rather  than  having  it  standing 
idle  in  the  shop  for  several  days.  Other  advantages  of  this 
method  of  repairing  are  : — 

I — Comparative  low  cost. 

2 — Ease  and  convenience  of  doing  the  work. 

3 — Speed  of  operation. 

4 — Reliability  of  results. 

5 — Saving  of  material. 

6 — Almost  unlimited  application. 

7 — Less  skilled  labor  required. 

APPLICATION 
There  is  a  wide  range  of  application  for  electric  welding 
in  connection  with  the  repair  of  railway  equipment  details  but 
experience  has  shown  that  it  requires  a  trained  operator  with 
good  judgment  to  select  the  proper  method  of  welding  in  order 
to  secure  the  best  possible  results  in  each  individual  case.  Any 
one  method  should  not  be  condemned  because  of  its  failure  to 
meet  all  requirements,  as  electric  welding  has  its  limitations  and 
to  get  the  best  results,  must  be  handled  and  applied  intelligently. 
Some  of  the  parts  where  electric  welding  may  be  used  to  ad- 
vantage in  the  repair  of  the  equipment  are  as  follows : — 

Truck   frames  Flanges  on  worn  car  -nheels 

Brake  hangers  Worn  axles 

Journal  boxes  Worn  journals  on  armature  shafts 

Gear   cases  Broken  and  worn  motor  frames 

Resistors  Axle  brackets 

Drawheads   and  under - 

framing  Damaged  pinion  fits  of  shafts 

Worn  dowel  pin  holes  in 

axle   bearings  Controller  frames 

In  addition  to  the  above,  railway  tracks  can  readily  be 
repaired  by  building  up  material  on  cupped  rails,  worn  frogs 
^"t,-  /^'■°**"°'^'*^''S  at  points  subjected  to  rapid  local  wearing, 
which  are  hammered  by  the  wheels  of  the  passing  cars.  It  is 
also  quite  extensively  used  in  rail  bonding,  where  steel  re-in- 
forced  bonds  are  used. 

EQUIPMENT 

The  following  equipment  is  necessary  for  an  electric  weld- 
ing outfit : — 

Welding  booth. 

Motor-generator  set — preferably  of  portable   tvne 

Electrode   holders   with   cable. 

Carbon  and  metal  electrodes. 

The  operator  should  be  supplied  with  the  following- — 

Helmet   or   shield 

Gauntlets  or  gloves 

Heavy  shoes  with  tongues. 

Leather  apron. 

METAL  ELECTRODE   WELDING 

=t»  ,^^'"h  this  method,  the  operator  uses  a  rod  of  low  carbon 
steel  as  the  negative  terminal  of  the  circuit  to  draw  the  arc, 
TV  "r^j'-  '"*^'^'  ^'■°'"  ''^'^  "'^f^'  electrode  onto  the  work 
inis  method  is  comparatively  slow  and  uses  a  relatively  small 
amount  of  power.  The  metal  is  deposited  more  uniformly  and 
tne  wem  IS  stronger  and  has  a  more  regular  appearance  than 
when  made  with  the  carbon  electrode  method.  Since  the  filler 
in  this  process  15  carried  directlv  to  the  weld  bv  the  arc,  it  can 
be  used  on  vertical  surfaces  and  overhead  work.  For  the  above 
reasons,  the  metal  electrode  method  is  more  generallv  used  in 
connection  with  all-round  repair  work. 

Operators-Experience  has  shown  that  a  man  with  a  slow 
steady  easy-going  manner  can  be  trained  to  be  a  good  welder 
witnin  a  month. 

Preparation  of  the  u'eld-The  parts  should  be  thoroughly 


cleaned,  using  a  sand  blast  or  a  metal  wire  brush.  If  edges  are 
to  be  welded,  both  should  be  beveled  so  that  new  metal  can  be 
deposited  in  the  crack. 

The  Electrodes  should  be  a  high  grade  of  low  carbon 
steel  wire,  cut  14  to  18  in.  long.  Diameter  of  electrodes,  from 
1^  to  A  in.  depending  upon  the  current  values  used  which  will 
vary  from  50  to  225  amperes. 

The_  Jl' elding  Current  should  be  of  such  a  value  that  the 
depth  of  the  arc  crater,  or  "bite",  is  not  less  than  tV  in. 

Arc  Length— Preierahh  use  an  arc  i^  to  %  in.  in  length 
as  it  gives  better  fusion,  resulting  in  a  more  solid  weld. 

CARBON   ELECTRODE   WELDING 
In  this  method  the  operator  uses  a  rod  of  carbon  as  the 
negative  terminal  of  the  circuit  to  draw  the  arc,  which  fuses 
metal  on  the  weld,  from  a  filler  rod  held  in   the  hand  of  the 
operator.  This  method  is  very  rapid,  but  requires  a  compara- 
tively large  amount  of  power.  The  quality  of  the  weld  in  the 
hands  of  the  average  operator  is  not  quite  so  good  as  when 
made  using  the  metallic  electrode,  and  is  not  especially  adapted 
to  work  where  strength  is  of  prime  importance.  However,  this 
method  is  used  to  good  advantage  in  the  following  applications: 
1 — Welding  cast  iron,  cast  steel,  and  non-ferrous,   (copper,  brass, 
etc.)    metals. 
2 — Cutting  of  cast  iron. 
3 — Rapid  deposit  of  metal  to  build    up    surfaces    where    strength 

is  of  minor  importance. 
i — Melting  and  cutting  up  of  scrap  iron. 

5 — Remelting  of  surfaces  to  improve  the  appearance  or  fit. 
6 — Deposit  of  hard  metal  on  wearing  surfaces. 
7 — Cutting  and  welding  of  sheet  metal. 

Operator—Same  as  for  "Metal  Electrode  Welding". 

Preparation  of  ((/c/af— Same  as  for  "Metal  Electrode  Weld- 
ing". 

Electrodes — These  were  originally  made  of  carbon,  but 
recent  experience  shows  that  graphite  has  a  longer  life  and 
makes  a  softer  weld.  These  electrodes  are  from  8  to  12  in.  long, 
tapered  at  one  end,  and  vary  in  diameter  from  %  to  1.5  in.  de- 
pending upon  current  values,  which  will  vary  with  the  work 
from  100  to  800  amperes. 

Filler  Material — Use  commercially  pure  iron  rods  from  ^ 
to  %  in.  in  diameter. 

TIw  Welding  Currents  used  in  this  process  are  between 
300  and  450  amperes.  They  may  go  as  high  as  600  to  800 
amperes,  depending  upon  the  work  and  speed  desired 

Arc  Length — In  general,  too  short  an  arc  will  deposit  carbon 
in  the  weld,  tending  to  harden  it.  Arc  lengths  will  vary^  with  the 
current.  On  the  average,  the  arc  should  be  from  %  to  I  in. 
with  a  250  ampere  circuit  and  ?i  to  1.5  in.  with  a  500  ampere 
circuit. 

PRECAUTIONS 

In  connection  with  electric  welding,  the  following  points 
should  be  given  special  attention : 

1 — Connect  the  positive  side  of  the  circuit  to  the  work. 

2 — Protect  the  eyes  and  body  from  the  arc. 

3 — Have  an  ample  length  of  flexible  cable  leads  to  allow  free  us« 
of  the  electrode  holder. 

4 — Thoroughly  clean  the  surfaces  to  be  welded. 

5 — Flux  is  not  essential,  but  is  a  source  of  danger,  as  it  may  con- 
taminate   the   weld. 

6— Maintain   a   steady  arc. 

7 — Heat  cast  iron  before  welding. 

OXY-ACETYLENE  WELDING 

This  method,  commonly  known  as  gas  welding,  is  used  very 
successfully,  especially  on  small  work  and  on  non-ferrous 
metals.  This  process  depends  upon  the  heat  produced  by  the 
combination  of  acetylene  gas  with  oxygen  in  a  common  blow 
pipe  or  torch. 

THERMIT  WELDING 
This  method,  which  is  primarily  a  casting  process,  is  used 
mostly  for  repair  work  where  considerable  metal  is  required, 
as  in  the  case  of  broken  motor  frames,  heavy  truck  castings, 
etc.  It  depends  on  the  chemical  combination  of  aluminum  filings 
mixed  with  oxide  of  iron  which,  when  primed  by  a  magnesium 
powder,  generates  an  intense  heat  and  fuses  the  metal  into  a 
molten  mass.  John  S.  Dean 


484 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.   10 


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velope should  accompany  each  query.  All  data  necessary  for 
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expecting  a  reply. 


2042 — RECOXXECTING      A      DIRECT-CURRENT 
GENERATOR      FOR      HALF      VOLTAGE      AND 

DOUBLE  CURRENT — A  direct-current  gen- 
erator of  1.87  kw,  125  volts,  15  am- 
peres, 1800  r.  p.  m.  has  been  changed 
to  one-half  former  voltage  in  the  usual 
way  by  reconnecting  the  armature  for 
double  current  and  the  four  field  poles 
with  compound  winding  for  one-half 
former  voltage.  What  changes  are  nec- 
essary, if  any,  on  commutator  and 
brushes?  There  are  31  segments  in  the 
commutator,  4  brush  holders  and 
brushes.  Size  of  brushes  tSi  in.  by  i  % 
in.  Width  of  commutator  bar  -h  in. 
Length  of  bar  or  brush  surface  lii 
inch.  Circumference  of  commutator 
10.5  in.  It  is  desired  to  operate  this 
generator  at  40  amperes  and  62.5  volts 
for  2.5  hours  daily. 

c.  A.  M.  (wash) 

To  change  this  machine  over  to  a  gen- 
erator of  one-half  voltage  and  twice  the 
current,  the  two-turn  armature  coils  are 
opened  on  the  commutator  end  and  the 
two  turns  connected  in  parallel.  The 
commutator  bars  will  have  to  be  re-slot- 
tcd  to  take  four  wires  per  bar.  The  field 
coils  should  be  connected  in  series-paral- 
lel. The  cross-sectionai  area  of  the 
brusliO!^  will  have  to  be  approximately 
doubled.  Since  a  brush  now  only  covers 
three-fifths  of  a  commutator  bar,  a 
brush  of  about  1%  in.  by  Vi  in.  could  be 
used,  in  order  not  to  require  a  new  com- 
mutator. Changing  the  size  of  the 
brushes  necessitates  new  brush  holders 
Thirty  amperes  could  be  drawn  from 
this  machine  after  changing  it  over  to 
half-voltage,  with  the  same  temperature 
rise  as  with  the  original  rating.  A 
machine  of  this  size  would  in  all  proba- 
bility have  reached  a  constant  tempera 
ture  in  2.5  hours  which  means  that  a  2.5 
hour  rating  is  the  same  as  a  continuous 
rating.  It  is  probable,  however  that  on 
the  basis  of  a  50  degrees  C.  rise,  35  amp- 
eres could  be  drawn  from  this  machine. 
H.  s. 

2043 — CLEANING  WATER  COILS  OF  TRANS- 
FORMER— We  have  in  service  six  SCO 
kv-a  oil-insulated,  water-cooled  trans- 
formers. These  transformers  have  been 
in  ser%'ice  for  a  number  of  years  but 
we  never  experienced  any  trouble  in 
keeping  the  water  coils  cleaned  out, 
imtil  recently  the  water  was  changed 
and  the  pipes  were  stopped  up  by  a 
deposit  of  lime.  The  only  way  we  were 
able  to  clean  out  these  coils  was  to 
bore  holes  in  a  number  of  places  and 
pour  in  muriatic  acid.  This  method 
was  successful  in  that  it  cleaned  out 
the  lime  but  it  was  very  slow  and  it 
wa^  necessarj-  to  repair  the  pipe 
wherever  a  hole  was  drilled.  Please 
advise  if  you  know  of  any  better 
method  for  cleaning  out  these  pipes. 

J.  o.  P.  (IND.) 

Running     a     muriatic     acid     solution 

through  a  cooling  coil  is  about  the  best 

known  method  of  removing  a  coating  of 

lime.    If    the    cooling   coil    was    entirely 


clogged  up  so  that  liquid  could  not  be 
forced  through,  the  method  of  getting 
the  acid  in  was  probably  as  good  as  could 
be  devised.  When  a  cooling  coil  begins 
to  clog  up  it  is  indicated  by  a  decreased 
flow  of  water  and  an  increased  tempera- 
ture of  the  oil.  When  clogging  is  suspect- 
ed, the  matter  should  be  looked  into  at 
once.  vv.  M.  M. 

2044 — FREQUENCY         AND         POWER-FACTOR 

METERS— In  calibrating  both  frequency 
and  power-factor  meters  are  they  ad- 
justed so  as  to  return  to  some  parti- 
cular mark  on  the  scale  when  the  cur- 
rent carrj'ing  coils  are  on  open  circuit, 
or  is  the  indicating  needle  supposed  to 
stay  at  any  particular  place  where  it 
happens  to  be  when  the  circuit  is 
broken.  E.  M.  (n.  y.) 

The  indicating  needle  of  frequency  and 
power- factor  meters  is  mounted  on  a 
shaft  which  carries  the  armature.  As  this 
armature  is  allowed  to  rotate  freely  in 
either  direction  in  the  more  common 
types  of  meters  it  is  obvious  that  the  in- 
dicating needle,  when  perfectly  balanced, 
will  stop  where  it  happens  to  be  when 
the  circuit  is  broken.  M.  M.  B. 

2045 — SPEED    OF    INDUCTION     MOTOR — How 

many  revolutions  will  a  25  cycle,  three 
phase  induction  motor,  rated  at  20  hp, 
450  r.  p.  m.  make  at  o,  Vi ,  % ,  %  load, 
if  connected  to  a  30  cycle,  three-phase, 
alternating-current  circuit? 

S.  J.  P.  (MICH.) 

It  is  impossible  to  make  a  definite 
reply  to  this  question  without  knowing 
fully  the  operating  characteristics  of  the 
motor,  and  specifically  the  speed  torque 
of  this  particular  motor.  Certain  general 
assumptions  may,  however,  be  made.  If 
the  voltage  applied  to  the  motor  is  in- 
creased in  direct  proportion  to  the  in- 
crease in  frequency,  the  operating  char- 
acteristics of  the  motor  will  remain  ap- 
proximately the  same,  which  will  mean 
that  you  have  the  same  percent  slip  at  all 
loads  that  you  had  on  25  cycles  and  the 
speed  of  the  motor  will  be  increased  20 
percent  above  its  present  value  at  all 
loads.  If,  however,  the  motor  is  operated 
on  30  cycles  at  the  present  voltage  you 
will  have  the  condition  ot  a  motor  oper- 
ating at  16.6  percent  below  normal  volt- 
age and  under  this  condition  the  slip  will 
be  increased  materially  at  all  loads.  On 
the  basis  that  the  450  r.  p.  m.  mentioned 
in  the  question  is  the  speed  at  full  load, 
it  is  evident  that  you  have  a  six-pole 
motor  operating  normally  at  a  high  per- 
cent slip.  As  mentioned  above  it  is  irn- 
possiblc  to  calculate  what  the  speed  will 
be  for  the  entire  range  of  load  under  the 
new  conditions  but  it  is  probable  that  at 
30  cycles  and  rated  voltage,  the  speeds 
w-ill  be  of  the  general  order  of  those 
given  below :  at  zero  load,  quite  close  to 
synchronous  speed  or  600  r.  p.  m. ;  at 
one-fourth  load,  around  560  to  570  r.  p. 
m. ;  at  one-half  load,  around  5,30  to  540 
r.  p.  m. :  at  three-fourths  load,  around 
475  r.  p.  m. ;  at  full  load,  aroiuid  450 
r.  p.  ni.  C.  R.  R. 


2040 — COMPRESSOR  CAUSING  FLUCTUA- 
TIONS IN  Current  Supply— We  are 
manufacturers  of  CO2  refrigerating 
machines.  At  present  we  have  a  con- 
tract to  install  an  80  ton  machine  for 
the  purpose  of  cooling  air  in  a  theater. 
Heretofore,  on  large  compressors 
operating  in  moving  picture  theaters 
considerable  trouble  has  been  exper- 
ienced with  the  projection  machine,  due 
to  fluctuations  in  the  current  caused  by 
the  compressor  strokes.  Now  we  are 
trying  to  remedy  this  matter  by  using 
the  proper  flywheel,  and  before  we  go 
very  far  in  our  calculations  we  would 
like  some  comprehensive  data  regard- 
ing the  calculations  of  flywheel  weights 
for  such  applications,  as  a  basis  for 
this  and  future  installations.  Therefore 
we  will  be  greatly  obliged  if  you  Can 
furnish  us  with  such  data  covering 
both  belt  drive  with  an  induction 
motor;  also  with  s>Tichronous,  the  syn- 
chronous motor  to  be  cither  belt  or  dir 
ect  connected,  although  we  feel  that  dir- 
ect connection  in  this  case  would  be  im- 
practical, as  the  compressor  speed  is 
only  90  r.  p.  m.  The  dimensions  of  the 
compressor  are  as  follows  : — bore  6-5^ 
inch,  stroke  24  inch,  discharge  pressure 
60  atmospheres,  suction  pressure  22 
atmospheres.  All  information  that  you 
can  give  us  regarding  the  proper  fly- 
wheel for  belt  drive  or  synchronous 
motor  for  direct  drive  will  be  greatly 
appreciated.  E.  j.  i.  (ill.) 

This  is  a  question  that  cannot  be  given 
a  definite  answer.  In  the  first  place  we 
do  not  know  how  much  current  fluctua- 
tion can  be  tolerated.  If  this  were  known 
the  required  flywheel  effect  could  be  cal- 
culated with  a  fair  degree  of  accuracy 
for  a  direct-connected  unit.  For  a  belted 
unit  there  is  a  damping  effect  due  to  the 
belt  which  should  make  conditions  better 
than  calculations  indicate.  The  method  of 
treating  this  problem  when  synchronous 
motors  are  used,  assuming,  of  course, 
that  the  permissible  current  fluctuation 
is  known,  is  covered  in  an  article  pub- 
lished in  the  Tournal  for  Januar>'  1920. 
In  this  article  the  limit  of  angular  varia- 
tion is  set  at  three  electrical  degrees 
which  means  about  five  to  ten  percent 
periodic  change  in  current.  The  change  in 
line  voltage  which  accompanies  a  given 
current  fluctuation  is  governed  entirely 
by  the  power  supply  so  that  a  unit  which 
gives  no  trouble  in  one  installation  will 
not  necessarily  be  satisfactor>-  in  another 
If  experience  shows  that  the  flywheel 
effect  required  is  excessive  it  would  pro- 
bably be  well  to  consider  supplying  the 
projection  machine  from  a  motor-genera- 
tor set.  Also  would  suggest  that  this  trou- 
ble could  beavoided  by  building  compres- 
sors having  the  proper  number  of  cylin- 
ders driven  from  a  crank  shaft  thus  ob- 
taining an  almost  uniform  load.  It  has 
been  found  that  two  or  three  single 
cylinder  compressors  units,  when  operat- 
ed at  the  same  time,  cause  less  trouble 
than  when  one  unit  is  operated  alone. 

Q.  G.   &  M.   M.  B. 


The  Electric  Journal 


VOL.   XVIII 


November.  1921 


No.  11 


.  .  The  application  of  mechanical  power 

Electricity  ^^     ^j^^      manufacture      of      textiles, 

.  which   formed  the  beginning  of   the 

J  textile  industry  was  developed  in  the 

n   ustry  j^^^.   ^^^^   ^^   ^^^   eighteenth    century 

in  England,  when  power  machinery  for  the  production 
of  textiles  was  invented.  These  ideas  were  first  in- 
corporated in  this  country  in  a  cotton  mill  started  at 
Pawtucket,  Rhode  Island  in  1790.  The  growth  of 
this  industry  has  been  rapid  and  at  the  end  of  1919 
there  were  6521  establishments  whose  total  value  of 
product  amounted  to  $5  127  000  000  annually.  Cotton, 
wool,  silk,  jute,  flax  and  other  fibres  are  woven,  knitted 
and  finished  in  great  variety  of  forms,  not  only  for 
clothing,  floor  coverings  and  other  domestic  purposes, 
but  for  belting,  tire  fabric,  artificial  leather,  automobile 
tops,  insulating  materials,  etc. 

For  many  years  the  water  wheel  was  the  prime 
mover  used ;  later,  the  steam  engine  came  into  exten- 
sive use.  In  either  case  the  prime  mover  supplied 
power  to  a  main  line  shaft  from  which  it  was  trans- 
mitted to  the  various  machines  by  means  of  shafts, 
ropes  and  belts.  While  it  would  be  expected,  with  a 
power  transmission  system  of  this  kind,  that  the  fric- 
tion losses  would  be  considerable,  and  the  speed  regu- 
Irtion  not  all  that  could  be  desired;  nevertheless,  in 
many  of  the  mills  were  to  be  found  power  transmis- 
sion systems  which  were  a  credit  to  the  engineering 
ability  and  ingenuity  of  those  responsible  for  the  in- 
stallation. 

In  this  industry  the  question  of  speed  regulation 
is  most  vital,  as  upon  it  depends  the  quality  of  the 
finished  material.  Moreover,  by  operating  the  ma- 
chines at  the  highest  permissible  speed,  the  maximum 
production  is  obtained.  Therefore,  any  motive  power 
that  would  operate  the  machines  at  a  constant  speed  is 
greatly  to  be  desired.  While  an  approach  to  this  con- 
dition could  have  been  made  by  the  substitution  of  a 
number  of  prime  movers,  each  to  drive  smaller  groups 
of  machines,  such  a  scheme  is  impractical,  from  an 
operating  and  economy  standpoint,  for  any  but  electric 
drive. 

While  the  introduction  of  electricity  in  the  form  of 
ciirect-current  would  have  permitted  a  more  economical 
method  of  transmitting  power  as  compared  to  me- 
chanical drive,  the  use  of  a  direct-current  motor  was 
given  very  little  consideration  on  account  of  the  fire 
hazard. 

The  alternating-current  system  affords  an  excel- 
lent method  of  transmitting  power,  while  the  squirrel- 
cage  induction  motor  has  the  proper  speed-torque  char- 
acteristics and,  in  addition,  eliminates  the  fire  hazard. 
The  first  squirrel-cage  induction  motors  were  installed 


to  drive  groups  of  machinery  in  plant  additions  where 
the  prime  mover  had  insufficient  capacity  to  take  care 
of  the  added  load,  or  were  used  to  replace  prime 
movers,  where  the  latter  had  outlived  their  usefulness. 
From  an  operating  standpoint  induction  motors  were 
I'ighly  satisfactory  and  in  a  short  time  were  firmly 
established.  It  was  soon  discovered  that  the  machines 
driven  by  the  motors  had  fewer  broken  ends,  due  to 
the  more  nearly  constant  speed  at  which  they  oper- 
ated; furthermore,  that  increased  production  was  be- 
ing obtained  on  account  of  the  fact  that  the  speed  of 
the  machine  was  higher  than  the  average  of  the  speed 
on  the  machines  that  were  mechanically  driven  from 
the  prime  mover.  This  led  to  the  use  of  additional  mo- 
tors and  separating  the  machines  into  smaller  groups, 
which  gave  material  reduction  in  the  friction  losses  and 
a'  the  same  time  improved  the  operating  conditions. 

With  each  sub-division  in  the  grouping  of  the  ma- 
chines, thereby  making  use  of  smaller  motors,  it  was 
natural  that  attention  should  be  given  to  the  operating 
characteristics  of  the  various  machines  with  a  view  to 
applying  an  individual  motor  to  each  machine.  This 
work  has  been  carried  on  over  a  number  of  years,  until 
at  the  present,  time  a  satisfactory  individual  motor 
drive  has  been  applied  to  a  large  portion  of  the  ma- 
chines used  in  this  industry. 

The  increase  in  electric  textile  drives  has  been  very 
rapid,  as  shown  by  the  following  tabulation  :-^ 


All  new  mills  are  laid  out  with  the  idea  of  using 
the  latest  type  of  electric  drive  and  each  year  a  num- 
ber of  mechanically-driven  mills  are  changed  over  to 
electric  drive.  The  electric  drives  are  increasing  at  a 
much  higher  rate  than  the  total  horse-power,  indicat- 
ing the  gradual  elimination  of  all  other  forms  of  drive. 
This  extensive  growth  has  been  due  to  the  recognized 
superiority  of  motor  drive  over  other  forms  and  to  the 
r.-ipid  growth  of  the  central  stations. 

Instead  of  seeing  new  power  houses  built  in  con- 
nection with  the  new  mills,  it  is  now  a  familiar  sight 
to  see  a  small  substation  in  which  is  installed  the  neces- 
sary transformers  and  switching  equipment  to  dis- 
tribute the  power  from  the  power  company's  lines. 

In  the  finishing  end  of  this  industry,  where  it  is 
necessary  to  have  adjustable  speed  on  a  number  of  the 
machines,  the  direct-current  motor  is  used  quite 
Lirgely.  In  the  past  few  years,  some  very  extensive 
niiprovements  have  been  made  in  the  driving  of  ma- 
chines in  finishing  plants  which  have  shown  quite  a 
saving  over  previous  methods  of  drive. 

The  design  of  electrical  equipment  for  the  textile 


486 


THE   ELECTRIC   JOURNAL 


Vol.  XVI I r,  No.  II 


industry  has  been  given  very  careful  consideration  by 
the  leading  manufacturers,  as  it  was  found  that  con- 
d'tions  in  this  industry  were  different  from  those  found 
in  other  industries  and  that  special  features  were  nec- 
essary in  order  to  have  the  equipment  give  good  operat- 
ing service.  J.  R.  Olnhausex 


.         The    textile    industry    is    the    largest 
Electnficati     <    ^^^  ^^^^  ^^  ^^^  ^j^^^^  industries  in 

r     1     J     New     England.       There     are     over 

_       .°  twelve    hundred    establishments    re- 

I  cxtilc 

I  presenting    all    the    subdivisions    of 

the  industry,  i.e.  mills  for  cotton, 
wool,  worsted,  silk  and  other  fibres  and  the  finishing 
of  the  final  product.  The  total  horse-power  involved 
to  operate  these  mills  is  in  excess  of  a  million  and  a 
quarter,  and  the  rate  of  increase  during  the  past  fifteen 
years  has  been  approximately  four  percent.  At  the 
present  time  over  one-fifth  of  this  power  has  its  source 
in  water  wheels  located  on  the  mill  properties,  about 
three-fifths  is  generated  by  steam  by  the  mills  them- 
selves, and  about  one-fifth  is  purchased  from  the  cen- 
tral power  companies.  About  30  percent  of  the  power 
is  transmitted  electrically. 

The  tendencies  in  connection  with  the  generation 
and  distribution  of  power  have  been: — 

I — To  redevelop  existing  water  powers. 

2 — To  purchase  central  station  energy. 

3 — To   use  motors  direct  connected  to   the   individual   ma- 
chines. 

These  tendencies  ha\e  been  very  largely  accele- 
rated by  higher  prices  of  fuel  material  and  labor. 

Water  power  determined  the  location  of  the  older 
mills.  Many  of  these  mills  still  have  wheels  of  old 
design  now  operating  at  an  efficiency  of  60  to  70  per- 
cent and  with  a  capacity  to  handle  the  stream  flow 
from  eight  to  nine  months  of  the  year.  With  coal  at 
the  present  prices  the  saving  to  be  effected  with 
modern  wheels  with  an  efficiency  of  85  to  90  percent 
and  a  capacity  to  handle  the  stream  flow  for  ten  to 
eleven  months  almost  invariably  justifies  a  redevelop- 
ment on  this  basis  alone,  without  regard  to  the  advan- 
tages incident  to  the  rearrangement  of  control  and 
electric  transmission. 

The  connected  load  of  the  central  power  stations 
in  New  England  has  been  increasing  at  the  rate  of 
nearly  100  000  hp  per  year  and  a  substantial  part  of 
this  is  represented  by  the  textile  industry.  New  mills 
without  use  for  low-pressure  steam  in  the  process  or 
for  heating,  or  where  the  steam  requirements  do  not 
synchronize  with  the  load,  almost  invariably  purchase 
their  power  where  it  is  available.  The  elimination  of 
the  investment  for  power  plant,  the  location  of  the 
plant  without  respect  to  condenser  water,  the  avoid- 
ance of  difficulty  in  the  securing  of  fuel  and  labor  are 
often  among  the  considerations  influencing  the  pur- 
.  chase  of  power. 


In  the  older  mills,  with  existing  engine  and  boiler 
plants,  the  purchase  of  power  is  often  brought  about 
by  the  condition  of  this  equipment.  Sooner  or  later 
the  management  is  confronted  with  the  problem  of 
renewing  the  prime  movers  or  boilers  or  both,  or  pro- 
viding some  other  source  of  power.  It  often  develops 
that  the  initial  cost  of  electrification  exceeds  by  little 
the  cost  of  new  boilers  and  their  installation  alone,  and 
that  power  can  be  purchased  at  a  cost  not  exceeding 
the  cost  of  operating  a  renewed  plant.  In  this  event 
the  decision  is  in  favor  of  the  purchase  of  power,  which 
also  secures  the  advantages  of  electric  transmission. 

The  original  installations  of  electric  transmission 
involved  large  motors  and  the  elimination  of  the  larg- 
est belts  and  headshafts  only,  leaving  the  shafting  and 
belts  and  providing  but  few  sources  of  constant  speed 
(the  motors)  instead  of  one  (the  engine.)  It  is  now 
very  generally  recognized  that  the  proper  arrangement 
of  motor  drive  is  to  put  the  motor  on  the  driven  machine 
itself,  so  far  as  this  is  practical,  eliminating  mechanical 
transmission  and  providing  a  source  of  constant  speed 
nt  every  machine.  Motors  on  the  machines  themselves 
may  also  be  provided  with  characteristics  that  can  not 
be  readily  provided  mechanically,  such  as  automatic 
acceleration  and  deceleration  between  pre-determined 
speeds  or  control  remote  from  the  drive  and  convenient 
for  the  0])erator. 

Some  interesting  tests  were  recently  made  in  four 
different  and  well  conducted  mills  to  determine  the  re- 
lative variation  in  the  front  roll  speed  of  spinning 
frames  driven  by  three  different  methods,  mechanical, 
four  frame  and  individual  drive.  In  each  of  the  mills 
the  tests  were  made  in  a  single  row  of  frames  across 
the  mills  and  the  results  obtained  in  each  mill  were 
Eipproximately  the  same  as  secured  in  each  of  the 
others.  With  mechanical  drive  the  average  variation 
in  speed  from  the  highest  speed  to  the  lowest  was  in 
excess  of  six  percent  and  no  data  was  secured  to  de- 
termine whether  the  machine  at  the  highest  speed  was 
running  too  low.  With  four  frame  drive  the  varia- 
tion in  speed  was  in  excess  of  two  percent.  With  in- 
dividual drive  there  was,  of  course,  no  variation. 

The  idea  of  using  individual  motor  drive  to  pro- 
vide a  source  of  constant  speed  at  the  producing  ma- 
chines themselves  has  been  very  largely  carried  out  m 
the  new  mills  recently  built  in  New  England.  Shaft- 
ing hangers  and  belts  have  largely  disappeared,  and  the 
average  horse-power  is  about  1.5  in  one  of  thc^e  new 
cotton  cloth  mills. 

While  the  use  of  individual  drive  cannot  be  so 
Irrgely  undertaken  in  electrifying  an  existing  mill,  the 
tendency  is  the  same  i.e.  to  get  the  source  of  constant 
speed  as  close  as  possible  to  the  driven  machine.  The 
use  of  individual  drives  in  these  mills  often  comes 
about  when  the  old  machines  are  replaced  with  new,  or 
additional  macliines  are  installed. 

G.  D.  BowNE,  Jr. 


The  CojiU'a]  vSiaiJon  aiiJ  llio 


mm 


F.  S.  ROOT 


NO  textile  manufacturing  plant  would  be  built  to- 
day for  anything  but  electric  drive.  One  cannot 
be  so  positive  in  asserting  that  such  an  electrically 
equipped  mill  would  invariably  purchase  its  energy 
from  the  central  station.  Nevertheless,  we  firmly 
believe  that  in  the  very  near  future,  no  textile  mill,  new 
or  old,  will  any  more  think  of  making  its  own  power 
than  it  would  of  making  its  own  looms.  We  base  this 
belief  on  the  only  means  of  judging  the  future,  that 
is  on  events  of  the  past. 

In  any  change  in  industrial  methods,  it  is  safe  to 
consider  that  whatever  is  adopted  as  good  practice  b}' 
the  most  conservative  section  of  the  country,  will  cer- 
tainly be  followed,  (and  generally  anticipated)  by  the 
rest  of  the  country.  New  England  is  admittedly  more 
conservative  as  regards  changes  and  innovations  m 
methods  of  textile  manufacturing  than  is  the  South 
and,  therefore,  we  will  confine  our  study  to  one  city 
only,  noted  for  its  conservatism  along  textile  lines  ;  as- 


ToLiI  Electnfied 
July  -  1916 
3066  Hp. 

kv 

SI  Motor   InslaUed 
C-«Hp 

/- 

/a 

V  I.       ■  ^ 

,j         ■       '/-^^lx^»555^'^ 

FIG.    I — THE  INTRODUCTION   OF  CENTRAL   STATION   SERVICE 
INTO    MILL   C 

suming  that  anything  meeting  with  ready  acceptance  in 
its  textile  plants,  would  not  be  too  radical  .for  any 
other  section  of  the  country. 

Up  to  1911,  there  were  over  one  hundred  cotton 
mills  in  the  town,  only  one  or  two  of  which  were  elec- 
trically eqiiipped,  and  none  buying  energy  of  the  cen- 
tral station,  except  in  a  few  cases  where  a  machine 
shop  or  an  elevator  might  have  had  a  motor  put  in  t.) 
be  used  for  overtime  or  emergencies.  In  1911  a  new- 
mill  was  erected,  of  50  000  spindle  capacity,  requirin.t,' 
1500  horse-power  in  motors  and  designed  solely  for 
the  use  of  purchased  power.  Despite  the  head  shak- 
ings of  the  owners  of  the  mechanically  driven  mills, 
this  plant,  "Mill  A,"  was  a  success  from  every  angle. 
It  was,  (and  still  is)  an  ideal  customer  from  the  cen- 
tral station's  viewpoint,  since  both  its  power-factor 
and  load  factor  are  very  4iigh,  and  about  one-third  of 
the  energy  purchased  is  used  for  night-time  running. 
At  the  present  time  this  mill  has  2000  horse-power  con- 
nected to  the  central  station's  lines  and  uses,  during 
normal  business  conditions,  over  400000  kw  hrs.  per 
month  with  a  demand  of  but  i3c;o  kw. 


About  the  same  time  that  this  mill  was  erected, 
a  new  narrow  fabric  factory,  also  designed  for  central 
station  service,  was  put  up,  requiring  about  300  horse- 
power. This  venture  has  also  met  with  success  and 
has  grown  to  over  400  horse-power  capacity. 


FIG.    2 — GROWTH    OF   CENTRAL   STATION   SERVICE   IN   LOCAL 
TE.KTILE   PLANTS 

The  first  mill  to  be  changed  from  mechanical  to 
electric  drive  (Alill  C)  was  an  old  mill,  incorporated 
in  1874.  Power  was  furnished  by  two  cross-com- 
pound Corliss-type  engines  rated  at  3300  hp,  and  up 
to  the  latter  part  of  1913,  no  electrical  energy  had  been 
purchased.  In  September,  1913,  a  radical  change  in 
the  styles  of  goods  produced  was  made,  resulting  in  an 
unbalanced  load  in  dilTerent  departments.  To  cor- 
rect this  it  was  decided  to  install  moto'iS  operated  by 
the  central  station  on  some  of  the  twisters  and  ring 
spinning  frames   for  overtime  use  only,  and  a   15   hp 


FIG.  3 — PREDICTED  FUTURE  GROWTH  OF  THE  USE  OF  CENTRAL 
STATION  POWER  IN  LOCAL  TEXTILE  PLANTS 

and  a  25  hp  motor  were  used  to  drive  nine  twisters, 
while  two  75  hp  motors  were  installed  on  a  group  of 
twenty-four  spinning  frames  and  slubbers. 

For  three  years  no  more  power  was  purchased,  al- 
though the  motors  which    were    installed    were    inter- 


488 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


mittently  used  and  were  sometimes  moved  to  other 
groups  of  machines  which  had  fallen  behind  in  produc- 
tion. Then,  in  the  last  months  of  1916,  war  orders  be- 
gan to  come  in  and  profiting  by  past  experiences,  this 
mill  began  to  install  more  and  more  motors  and  to  op- 
erate considerable  of  its  machinery  all  night. 


completely  electrified,  totalling  21  470  horse-power, 
and  twenty-six  others,  each  of  which  have  from  100 
to  1500  hp  of  purchased  power  installed,  totalling 
12  910  hp.  All  of  the  remaining  mills,  except  two,  use 
some  central  station  energy. 

The  growth  in  this  city   of   purchased    power    for 
textile  use  since   191 1   is  shown  in  Fig.  2.     The  most 


FIG.  4 — TECrMStH    Sl'liSTATION 

At  the  end  of  1017  about  half  the  mill  could  be 
driven  by  motors,  which  were  operated  at  night 
through  positive  jaw  clutches,  the  machines  driven  by 
them  being  carried  on  the  steam  drive  durmg  the  day 
At  about  this  time  .some  of  the  boilers  began  to  show 
signs  of  weakness  and  it  was  decided  to  relieve  them 
and  the  engines  also,  of  a  large  part  of  the  load  by  oj)- 
erating  all  motors  all  the  time.  The  saving  possible 
by  complete  electrification  of  the  whole  mill  then  be- 
came very  apparent  and  before  the  end  of  1918,  both 
engines  were  permanently  shut  down.  This  mill  now 
uses  about  550  000  kw-hrs.  per  month  and  has  3638  hp 
installed.  Fig.  i  shows  graphically  the  progress  of 
electrification  of  this  mill. 


FIG.  6 — MOTOR  DRIVEN  PICKERS 

important  point  to  be  noted  in  connection  with  this 
growth  is  the  fact  that  once  obtained,  it  is  never  lost 
but,  on  the  other  hand,  gathers  volume  at  a  rapidly  in- 
creasing rate. 

There  is  about  130000  horse-power  in  textile 
plants  in  the  city  under  consideration..  Rasing  future 
performances  on  past  history,  we  can,  from  the  cur\c 
given  in  Fig.  2,  plot  the  curve  shown  in  I-'ig.  3,  which 
would  seem  to  indicate  that  within  seven  years,  every 
mill  in  the  city  will  be  operating  entirel}'  on  central 
station  power.  This  condition  will  probably  fall  a 
little  short  of  realization,  partly  due  to  the  fact  that 
the  central  station  itself  will  probably  be  unable  to  take 
on  so  much  business  so  rapidly,  and  partly  to  the  fact 
that  some  of  the  mills  will  pass  through  an  inlermedi- 
ar\    stei>  before  using  purchased  power,  i.  e.,  some  of 


FIG.    5 — THREE   333    KV-A,    23OOO-55O  VOLT  TRANSFORMERS    IN 
SIIAWMUT   SUBSTATION 

The  use  of  central  station  service  in  other  mills 
also  took  added  impetus,  due  to  war  orders,  and  from 
the  few  motors  installed  for  overtime  work,  complete 
electrification  followed  after  the  war  in  several  cases. 
There    are  now  seventeen    textile  plants    in  this    city 


YIQ     7 — MOTOR  DRIVi:.\    SrlXXl^C    FRAMES 

the  plants  may  put  in  low-pressure  turbo-generators 
and  partly  electrify,  thus  postponing  complete  electri- 
fication from  the  central  station  for  several  years. 

Although  it  is  not  the  intention  to  take  up  motor 
applications  to  textile  work,  a  few  pictures  will  illus- 
trate    the     conditions     under     which     central     station 


November,  1921 


THE   ELECTRIC   JOURNAL 


service  in  the  city  is  rendered.  Energy  is  sold  at  23  000 
volts,  requiring  a  substantial  substation  which  is 
furnished  by  the  customer.  Some  of  these  have  been 
very  elaborate  and  have  cost  nearly  $30000  to  erect. 
Others  have  been  just  as  good,  though  less  pretentious. 
Fig.  4  shows  such  a  sub-station  which  utilized  in  part 
two  retaining  walls  of  the  former  coal  pocket  as  two 
sides  to  the  substation.  In  this  case  the  transformers 
were  housed  within  the  building.  Fig.  5  shows  another 
and  smaller  substation  in  which  the  transformers  were 
placed  outside  the  substation.  Both  methods  have 
been  perfectly  satisfactory. 

The  method  used  in  driving  pickers  by  individual 
motors,  Fig.  6,  is  introduced  for  three  reasons.     First. 


the  well-known  one  of  the  freeing  of  the  picker-room 
ceiling  of  all  overhead  shafting;  second,  the  neat  way 
in  which  these  motors  are  wired  up  (see  conduit  fol- 
lowing up  the  groove  of  the  "A"  frame)  ;  and,  third, 
because  of  the  type  of  lighting  used.  The  individual, 
direct-connected  motor-drives  on  the  spinning  frames 
shown  in  Fig.  7,  are  happily  becoming  common  practice 
in  many  cases  and  need  no  comment. 

The  growth  of  the  use  of  central  station  service 
in  textile  plants  has  been  very  rapid  in  the  past  five 
years  but  we  firmly  believe  that  it  is,  after  all,  only  a 
beginning,  and  that  the  next  five  years'  growth  will 
only  be  limited  by  the  central  station's  ability  to  take 
care  of  it. 


,lV(odorilkc 


;PIajii 


m 


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ox 


\A 


^Voi'-siod   Co, 


J.  B.  PARKS 

Philadelphia  District  Oltice, 
Wcstinghouse    Electric    &:    Mfg.    Company 


weave  rooms,  there  were  many  factors  to  be  con- 
sidered. For  instance,  when  a  belt  driving  a  loom 
from  an  overhead  shafting  becomes  loose,  the  loom 
bangs  off  more  frequently  and  sometimes  causes  the 
shuttle  to  fly  out,  making  it  dangerous  for  the  weaver, 
beside  breaking  out  warp  ends  which  represents  a  loss 
of  production.     Also  due  to  irregular  speeds  caused  by 


ANTICIPATING  the  keen  competition  which  was 
sure  to  come  with  the  return  of  the  textile  busi- 
ness to  a  normal  basis.  The  Prudential  Worsted 
Company  decided  during  1919,  thoroughly  to  modern- 
ize their  plant  at  Philadelphia.  The  plant  was  origi- 
nally operated  from  a  steam  engine  drive,  the  power 
being  transmitted  through  a  series  of  shafts  and  belt- 
ing to  the  various  floors  where  it  was  distributed  by 
belts  to  the  machines. 

First  a  detailed  study  was  made  of  the  processes, 
and  accurate  power  and  speed  tests  were  made  on  each 
machine.  In  the  weave  shed,  there  was  a  main  line 
shaft  in  the  center  running  the  length  of  the  room 
with  belts  running  to  countershafts  on  each  side  of  the 
main  shaft.  Due  to  the  non-uniformity  of  belt  ten- 
sion on  all  the  drives,  a  variation  of  six  to  eight  picks 
per  minute  was  found  to  exist  between  the  looms  op- 
erating from  the  countershafts  and  those  running  from 
the  main  shaft.  This  clearly  represented  a  loss  in  pro- 
duction. 

Modern  mill  operation  unquestionably  demands 
that  the  power  applied  to  a  machine  must  have  a  con- 
stant speed,  both  instantaneous  and  continuous,  and  the 
machine  in  each  case  for  maximum  production  must 
operate  at  the  highest  speed  consistent  with  the  quality 
of  work  and  the  ability  of  the  machine  operator. 

This  lead  to  the  consideration  of  individualizing 
each  machine  with  a  separate  motor,  for  only  in  this 
w  ay  could  the  elimination  of  speed  variation  be  accom- 
plished and,  in  addition,  many  other  advantages  be  ob- 
tamed,  such  as  elimination  of  overhead  shafting,  belt-     loose  belts,  trouble  is  experienced  by  cops  knocking  off 


I   .\ND  2 — VIEWS  OF  WEAVE  ROOM  BEFORE  .\ND  AFTER  INDI- 
\IDUAL    MOTORS    WERE    INSTALLED 


belt  guards,  etc.  Constant  speed  on  the  looms 
naturally  increases  the  total  power  consumed  by  the 
looms  over  that  previously  used,  but  this  was  more 
than  balanced  by  the  elimination  of  the  friction  load 
and  increased  production. 

In    analyzing    the    power    requirements     for    the 


ir  the  shuttle.  Now',  consider  each  loom  equipped  with 
a  waste  packed  bearing  motor,  the  upkeep  on  which 
includes  the  time  for  oiling  which  is  once  every  three 
months,  and  compare  this  with  the  amount  of  time 
consumed  in  a  belt  driven  |ilant.  in  oiling  loose  pulleys, 
cleaning  and   cutting  belts,   replacing  hurned-out  bear- 


49° 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


ings  due  to  tight  belts,  replacing  pulley  bushings  woni 
out  due  to  insufficient  oil  and  many  other  odd  jobs  that 
are  always  coming  up  with  the  belt  drives. 

Views  of  one  of  the  weave  rooms  before  and  after 
it  was  equipped  with  individual  motors  are  shown  in 
Figs.  I  and  2.  The  weave  room  on  the  third  floor  was 
similarly  equipped,  but  the  looms  in  this  room  were  all 
rearranged  so  as  to  provide  for  wider  aisle  spaces  and 
also  additional  machinery,  as  shown  in  Figs.  3  and  4. 

In  the  winding  room  it  was  found  that  the  power 
requirement  for  the  machines  themselves  was  so  small 
as  compared  with  the  total  power  required  for  the 
shafting  and  the  load  that,  for  economy,  each  machine 
was  equipped  with  a  small  motor  so  that  energy^  was 


of  sufficient  size  to  operate  the  beamer,  which  requires 
the  greater  load  of  the  two  and  is  operated  only  a  short 
time  out  of  the  total,  then  when  this  motor  was  run- 
ring  the  dressing  machine,  it  would  be  carrying  only 
about  Yi,  load.  For  a  one  motor  drive,  line  shafting 
and  belting  would  also  be  required  with  the  necessary 
belt  guards. 

In  this  way  all  line  shafting  was  eliminated,  witl) 
the  consequent  advantages  of  an  economical  and  ex- 
tremely flexible  plant.  For  instance,  when  it  is  neces- 
sary to  operate  some  sample  looms  or  any  one  depart- 
nient  overtime,  it  can  be  done  independently  of  the  rest 
of  the  mill. 

The  Prudential  Worsted  Company  have  been  run- 
ning continuously  on  the  electric  power  for  the  past 
two  years,  during  which  time  a  careful  record  has  been 
niade  of  the  increased  production  and  a  close  analysis 
made  of  the  rnh-rintaiics  gained  by  utilizing  the  modern 


FIGS.    3   AND   4 — WEAVE  ROOM    BEFORE   AND   AFTER   THE   LOOMS    WERE 
REARRANGED    AND    EQUIPPED    WITH    INDIVIDUAL    MOTORS 

being    consumed    only    when    a    given    machine    was 
actually  in  operation. 

In  the  warping  and  sizing  room,  a  similar  condi- 
tion existed.  Here  there  are  two  distinct  operations; 
first,  the  yam  is  dressed  or  sized  by  running  it  through 
a  starch  mangle,  over  a  small  set  of  dry  cans  to  a  large 
cvlindrical  frame  from  which  the  yam  is  later  beamed 
off  by  the  same  operator  on  to  a  beam  ready  for  the 
looms.  The  dressing  machine  is  operated  from  a 
separate  motor  which  is  closed  down  during  the 
beaming  off  process,  which  is  also  done  from  a  sepa- 
rate motor  and  this  latter  motor  is  closed  down  during 
the  former  process.  Two  motors  were  used  for  the 
warp  dresser  because  if  only  one  motor  was  used  and 


FIG.    5 — INDIVIDUAL    MilTOK   lUdVK  ON    SPOOLERS 

nethod  of  driving  textile  machinerj-,  a  few  of  which 
ire  outlined  below: — 

I— Five  percent  increased  production,  resulting  in  a  de- 
creased overhead  charge  for  a  given  output. 

2 — Tv^enty  percent  less  loom  breakage  and  consequently 
less  work  for  the  loom  fixers.  This  means  less  main- 
tenance and  fewer  looms  idle  due  to  mechanical  trou- 
bles. 

3— Elimination  of  loss  of  time  due  to  tightening  belts  and 
maintaining  belt  guards. 

4— Elimination  of  shuttle  fiyouts,  due  to  irregular  speeds, 
resulting  in  making  it  safer  for  the  weaver,  all  ot 
which  means  increased  production. 

5— Saving  in  cost  of  rebabbitting  bearings  on  the  loom 
countershafts  and  in  time  for  changmg  the  speed  ot 
the  looms.  The  old  way  to  change  the  speed  ot  a 
loom  was  to  remove  the  loom  countershaft  and  cl.ang« 
the  gearing.  The  new  way  is  to  loosen  four  bolts  in 
the  motor  base  and  change  the  motor  pinion 

6-The  utmost  freedom  regarding  arrangement  ot  machin- 
ery and  the  ability  to  operate  these  machines  inde- 
pendently of  the  rest. 

7-Extensions  and  additions  are  greatly   facilitated. 


i  ao 


T©i<i:lk  liidiBtry  k  Iho  CSouth 


JOHN   GELZER 

Atlanta  District  Office, 
Westinghouse  Electric  &  Mfg.  Company 


THE  textile  industiy  in  the  South  is  confined  en- 
tirely to  the  manufacture  of  cotton  products, 
i.e.,  duck,  sheetings,  print  cloths,  colored  goods, 
tire  fabric  and  numerous  yarns.  The  natural  advan- 
t  iges  of  the  Southern  states  as  a  cotton  manufacturing 
centre  have  impressed  capital  more  and  more,  with  the 
result  that  since  1900  the  majority  of  the  new  cotton 
.spindles  installed  in  the  United  States  have  been  in  this 
district.  In  1900  there  were  approximately  2  000  000 
cotton  spindles  in  the  South.  At  the  present  time  ap- 
proximately 16000000  spindles  are  installed,  which  is 
at  the  rate  of  650  000  spindles  per  year  for  the  past 
twenty  years. 

The  first  mill  to  be  equipped  with  electric  motor 
drive  was  put  in  operation  during  1894  in  Columbia, 
S.  C.     In   1904  about  five  percent  of  the  total  horse- 


FIC.    I— INTIIVUILWL  MOKiK  likl 


KI1I.\TE  PICKERS 


power  installed  was  electric.  The  advent  of  the  induc- 
tion motor  and  the  activities  of  the  hydroelectric  power 
companies  gave  an  impetus  to  the  electrification  of 
these  mills,  and  at  the  present  time  fifty  percent  of  the 
total  installed  horse-power  is  electrified. 

The  South  has  been  very  partial  to  electric  drive 
and  has  been  willing  to  accept  readily  the  new  types  of 
c^nve  as  they  have  been  advocated.  Since  the  bring- 
ing out  of  the  individual  motor  drive  for  various  ma- 
chmes  in  this  industry,  the  greatest  percentage  of  such 
drives  have  been  installed  in  southern  mills.  At  pres- 
ent the  individual  drive  is. used  extensively  on  new  elec- 
trifications, and  in  addition,  a  large  number  of  mills 
are  superseding  their  present  group  drives  with  in- 
dividual motors.  In  1912  the  average  size  of  motor 
used  was  50  hp.  This  has  decreased  to  4  hp  in  1919 
and  it  is  estimated  that  for  the  year  1922,  this  will  be 
further  reduced  to  3  hp,  thus  showing  the  extent  to 
v.'hich  the  South  has  gone  to  individual  motor  drive. 


The  typical  southern  mill  carries  on  the  following 
operations  in  the  manufacturing  of  their  product: — 
I — Picking. 
2 — Carding. 
3 — Combing. 

4 — Spinning  and  twisting;. 
5 — Weaving. 
() — Finishing. 


Before  the  cotton  can  be  spun  it  is  necessary  to 
break  the  bales,  remove  the  coarser  impurities  and 
eliminate  all  tangles  and  trash.  The  process  of  pick- 
ing consists  of  opening,  breaking,  and  passing  the 
cotton  through  the  intermediate  and  finisher  pickers, 
each  putting  the  cotton  fibre  in  better  shape.  It  is  de- 
livered from  the  picker  in  the  form  of  a  wide  roll  of 
cotton  batting  known  as  "lap". 

For  many  years  the  advantages  of  individual  1110- 
tur  drive  for  the  picking  room  have  been  recognized 
;ind  practically  no  mills  in  recent  years  have  installed 


FIG,   2 — TYPICAL  POWER  CIR\E  OF  A  liREAKING  PICKER 

any  other  form  of  drive.  The  motor  is  mounted  on 
the  A-frame  which  is  supplied  by  the  manufacturer 
and  is  belted  to  the  beater  shaft.  In  the  case  of  a 
double  beater  picker,  it  is  necessary  to  drive  from  each 
side,  so  that  a  double  extended  shaft  motor  with  an 
outboard  bearing  must  be  used,  as  the  distance  between 
centers  of  pulleys  varies  from  six  to  seven  feet. 
Lately  two-motor  drive  has  been  used  on  the  two-beater 
pickers  with  good  results,  the  motor  being  mounted  on 
each  end  of  the  A-frame  and  driving  to  the  beater 
shaft.  This  makes  a  better  mechanical  drive  and  the 
cost  is  very  little  greater  than  the  larger  motor  with 
the  special  shaft  and  outboard  bearing. 

CARDING 

From  the  picker  room  the  lap  goes  to  a  revolving 
Hat-type  of  card  whose  function  is  to  straighten  the 
cotton  fibres  still  further  and  remove  all  the  short 
length  fibres,  and  any  impurities  or  trash.  The  fibres 
are  straightened  out  by  combing  them  with  wire 
brushes  or  cards.  The  cotton  comes  from  the  cards  in 
the  form  of  a  soft  roping  known  as  "sliver"  about  % 
in.  in  diameter.  In  the  past,  group  drive  has  been 
used  in  the  driving  of  cards.     Common  practice  is  to 


492 


THE   ELECTRIC  JOURXAL 


Vol.  XVIII,  No.  n 


mount  a    15  to  50   hp   motor   on    the    ceiling   to    drive     ber,  which  continues  the  drawing  and  puts  some  twist 


a  line  shaft  from  which  the  cards  are  driven.  There 
has  recently  been  developed,  however,  an  individual 
drive  for  cotton  cards,  which  takes  care  of  the  strip- 
ping and  grinding  very  satisfactorily  and  in  addition, 
permits  the   starting  of   a   card  without  putting  on   a 


in    the   cotton,   and    for   the   first   time   puts   it  upon  a 


FIG.   3 — TYPICAL  POWER  CURVE  OF  .\  RE\0I.\1NG  FLAT  C.\RI) 

motor  several  times  too  large,  due  to  the  high  torque 
required  at  start. 

COMBING   AND    ROVING 

In  mills  for  fine  yarn,  or  where  coarse  yarns  of 
special  grades  are  to  be  made,  the  cotton  must  be  fur- 
ther treated  with  a  combing  process.  The  sliver  goes 
through   a   lap   machine,   reducing  the   sliver  to   a   lap 


FIG.  4 — IXUIVIDL'.AL  MOTOR  IIRIVF.  ON  REVOLVING  FL.\T  C.\RD 

about  a  foot  wide.  This  drawing  process  is  further 
to  straighten  the  fibre.  The  lap  then  goes  through  the 
combers,  which  actually  fine-tooth  combs  the  cotton  lap. 
."-'ix  or  eight  laps  going  through  the  machine  at  once 
are  combined,  condensed  and  formed  again  into  a  con- 


FIG.    5 — TYPIC.\L    POWER    CURVE   OF    .\    COMBER 

linuous  sliver.  The  processes  above  are  sometimes 
called  "drawing"  and  consist  of  a  continual  lengthening 
and  straightening  of  the  lap  of  sliver  as  it  goes  through 
each  machine.  Just  how  often  this  operation  is  per- 
formed depends  upon  the  grade  of  yarn  to  be  made. 

In  the  process  of  roving,  the  cotton  is  put  through 
slubbers,  intermediate  frames,  fine  and  jack  frames. 
From  the  drawing  frame  the  sliver  passes  to  the  slub- 


FIG.    6 — THE    TWO    .VXD    FOUR-FR.\ME    METHOD    OF    DRIVE    0\    ROVING 
FR.\MES 

spindle.  I'roni  the  slubber  it  goes  to  the  intermediate 
frames,  then  to  the  fine  frame  and  then  to  the  jack 
frame,  all  of  which  combine  two  or  more  cotton 
strands  by  twisting  and  drawing. 

Individual  motor  drive  has  been  worked  out  for 
ib.e  majority  of  these  machines  experimentally  and  the 
results  have  been  very  gratifying,  so  that  within  a 
^hort  time  this  type  of  drive  will  be  used  extensively. 
Ihe  majority  of  the  installations  at  the  present  time 
use  either  the  group  drive  or  else  the  two  or  four-frame 
drives. 

SPINNING    -AND    TWISTING 

The  cotton  taken  from  the  jacks  or  fine  frame  is 
j.ut    through    a   process   of    spinning   which    turns    the 


FIG.  7— TVPK'.\L  POWER  CURVE  OF  .\  SPINNING  FR.VME 

cotton  into  firm  yarn,  sufliciently  twisted  and  strong, 
ready  for  the  looms.  Practically  all  the  spinning  in 
the  South  is  what  is  known  as  ring  spinning.  The 
spinning  is  a  continuous  process  and  the  output  de- 
pends largely  on  maintained  speed.  The  horse-power 
for  spinning  represents  about  50  percent  of   the  total 


November,  1921 


THE   ELECTRIC   JOURNAL 


493 


in  the  mill  and  natural!}-  has  come  into  the  greatest 
consideration  for  individual  drive.  Individual  chain 
motor  drive  has  come  into  wide  use  through  a  general 
acceptance  of  its  distinct  advantages  over  any  other 
form  of  drive.  The  loss  in  production  due  to  belt 
slippage  is  entirely  eliminated.     Belted  applications  re- 


spooling,  warping,  sizing  and  slashing.  The  thread  is 
v.ound  from  the  spindles  onto  spools,  from  which  it  is 
V  ound  on  the  beam  by  the  warper,  and  then  passes  to 
the  slasher,  where  the  sizing  is  put  on,  then  to  the  loom. 
The  spoolers,  wari)ers  and  slashers  are  individually 
driven. 


FIG.    10 — TYPICAL  SPEED  TIME  CH-\RT 

Of    an    individual    motor-driven,    geared,    automatic    loom 
:omparcd  with  a  belt  drive  unit. 

The   majority  of   the   new   looms  are   individually 

motor  dri\'en,  tlnis  eliminating  all  belts  in  the  weaving 


Flu.    8    -INDIVIDUAL    Moluk    DlilVE   OX    SPIXNIXC    FR.>\MES 

quire  a  vertical  belt  drive  of  anywhere  from  25  to  30 
feet  and  a  small  amount  of  belt  stretch  results  in  loss 
of  speed  and  consequent  loss  of  production.  The 
silent  chain  individual  motor  drive  gives  flexibility,  as 
changes  in  number  of  yarns  can  be  made  by  changing 
n:otor  sprockets.  Chain  drive  makes  motors  of  stand- 
ard torque  characteristics  ideally  adapted  to  this  serv- 
ice. The  individual  spinning  drive  was  bought  out  in 
Southern  mills  and  practically  all  new  mills  are  being 
equipped  with  it. 

The  twisting  process  consists  of  taking  two  or 
i':.ore  yarns  after  it  comes  from  the  spinning  frame 
and  has  been  spooled,  and  twisting  them  into  a  single 
yarn.  The  enormous  demand  for  automobile  tire 
t:ibrics  has  largelv  increased  the  number  of  twisters  in 


FIG.    II — TYPICAI,  POWER  CURVE  OF  THE  COTTON  LOO.M 

plant.  This  drive  gives  a  higher  average  speed,  re- 
.■^ulting  in  increased  production.  It  also  reduces  loom 
fixing  and  gives  a  more  uniform  speed  and  a  better 
quality  of  finished  goods. 

A  typical  speed  time  chart  of  an  individual  motor- 
driven  geared  automatic  loom  compared  with  a  belt 
driven  unit  is  shown  in  Fig.  10.  With  the  belted  loom 
the  speed  is  varying,  due  to  belt  slippage  and  the  peak 
power  requirements  of  the  loom.  The  average  speed 
cbtained  is  considerably  lower  than  the  maximum 
speed  at  w^hich  the  loom  can  be  operated  on  account 
of  the  above  variations.  The  varying  speed  produces 
a  poorer  cloth,  less  yardage  and  causes  more  loom  fix- 
ing. The  geared  motor  drive  enables  the  manufacturer 
to    operate   the    loom    .'it    .'i    iikut    rnnstant    speed    and 


FIG.  9      INDIVIDUAL   MOTOR  CHAIN   DRIVE  ON   TWISTER  FRAMES 


-INSTAI.L.\TION   OF  INDIVIDUAL   MOTOR-DRIVEN    LOOMS 


use.       Individual    motor    drive    has    been    applied    to  nearer  the  maximum  that  the  loom  will  stand. 

twisters  in  a  similar  manner  to  that  of  spinning  and  is  finishing 

the  most  popular  drive  in  use  at  the  present  time.  ti  c  c   ■  \-        •     1   j       1,1       i  •         a 

^  The  process  of  finishing  includes  bleaching,  dye- 

\\EAViNG  ipg-^  mercerizing  and  printing,  but  only  a  small  percent- 

To  |>reiiare  the  threads  for  weaving,  on  the  loom,  r'ge  of  the  total  spindles  in  the  South  do  this  work,  the 

I.  IS  necessary  to  put  the  yarn  through  a  process  of  principal  output  being  unbleached  sheetings  and  yarn. 


494 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


TABLE   I— POWEE  EEQUIBED  BY  TEXTILE   MACHINEEY 


MACHINE  Morse - 

Power 

Single  beater  opener 5 

Two-beater  opener '-^ 

Two-beater  opener  with  single  hopper  feeder  and  cage  section..  10 

Trunking  opener  with  double  hopper  feeder 7.5 

Two  beater  roving,   waste  opener    7.5 

Single  beater  breaker  with  or  without  single  hopper  feeder 5 

Single  beater  breaker  with  condenser  section    7.5 

Single  beater  breaker  with  double  hopper  feeder  regulator 7.5 

Two  beater  breaker  with  condenser  section 10 

Two  beater  breaker  with  feeder 10 

Single  beater  intermediate  or  finisher  lapper 5 

Two  beater  intermediate  or  finisher  lapper 10 

Revolving  flat  card  production      350  lbs  per  week 0.75 

Revolving  flat  card  production  750  lbs.  per  week 1 

Revolving  flat  card  production  1000  lbs.  per  week 1.25 

Drawing  frames — 6  deliveries  per  hp 1 

Sliver  lap  machines ' .  -    0.5 

Ribbon  lap  machines 1 

Combers — 8  head -running — 130  single  nips  per  minute 0.75 

Combers — 8  head -running — 130  double  nips  per  minute ■.  .    1 

Slubbers — 45  spindles  per  hp. 1 

Intermediates — 55   spindles  per  hp 1 

Roving  frames — 65   spindles   per  hp 1 

Fine  or  jack  frames — 70  spindles  per  hp 1 

Spinning  frames — filling  yarns •  ■    5 

Spinning  frames — warp  yarns 7.5 

Twisting  frames 7.5  to  10 

Beam  twisting  frames  for  tire  fabric  yarns 10  to  15 

Mule  spinning  frame  90  to  100  spindles  per  hp 1 

Spoolers — 200   spindles  per  hp 1 

Cone   winaer t\  l' 

Beam  warper '■'■''* 

Ball  warper   ' 

Slasher  including  fan ^ 

Looms  up  to  40  inch  width   0» 

Looms  up  to  90  inch  width 0.75 

Looms  above  90  inch  e.xcepting  tire  fabric 1 

Tire   fabric   looms 2 

Trimmers ^ 

Polders 9'5 

Cloth  baling  press — 50  ton  pressure   ; 7.5 


The  mills  that  do  their  finishing  usually  arrange  the 
motors  in  groups,  but  undoubtedly  more  of  this  finish- 
ing work  will  be  done  in  the  South,  in  which  case  the 
individual  applications  that  now  predominate  in  other 
districts  will  be  used. 

Table  I  gives  a  summary  of  the  various  machines 
used,  with  their  power  requirements.  These  figures 
are  based  largely  on  the  use  of  individual  motor  drive.. 

The  mills  are  rapidly  extending  their  electrifica- 
tions to  new  fields  and  improving  their  present  elec- 
trification. Man}-  motor  drives  are  being  subdivided 
and  rearranged  to  get  more  efficient  drives  and  better 
output.  A  great  deal  of  attention  is  now  being  paid 
by  engineers  to  the  correct  system  of  lighting  and  vast 
improvements  have  been  made  in  this  direction,  the 
mills  superseding  their  old  lighting  systems  with  up- 
to-date  illumination.  Within  the  past  year,  actual 
figures  from  a  cotton  mill  in  Canada  shows  that  electric 
heating  can  be  installed  and  operated  as  economically 
as  a  low-pressure  steam  heating  system.  Work  is  be- 
ing done  towards  electric  heating  on  slashers,  tenters, 
etc.  and  it  can  reasonably  be  expected  that  in  the  near 
future  electricity  will  eliminate  the  boilers  that  are  now 
used  to  produce  the  steam  required  for  heating  pur- 
poses. 


foi' 


"CnKti 


O.  C.  SCHOENFELD 

Motor  Engineering  Dept., 
Wcstinghouse  Electric  &  Mfg.  Company 


sliding  contacts  is  highly  desirable  in  a  mill  where  the 
atmosphere  is  laden  with  inflammable  lint. 

The  textile   mill  covers  a  large  amount  of "  floor 
id   therefore   requires   long  line   shafting  and 


IN  THE  earlier  developments  of  electrical  drive  for 
textile  mills,  the  steam  engine  or  water  turbine 
was  replaced  by  a  large  electric  motor,  which  was 
belted  to  the  line  shafting  driving  the  entire  mill.  The 
motor  was  installed  in  what  was  previously  the  en- 
gine room,  where  operating  conditions  could  be  made 
to  suit  the  motor  and  therefore  a  motor  of   standard     predated  the  advantages  of  the  transmission  of  power 

by  electric  wiring,  and  soon  replaced  the  large  motoi 


space 

numerous  belts  when  one  driving  unit  is  used ;  so  that 

it  was  natural  that  the  textile  mill  operators  early  ap- 


design  and  construction  was  used.  These  applications 
offered  no  special  problems.  It  is  interesting  to  note 
how  the  special  features  of  motor  design  have  de- 
veloped as  the  motor  drive  has  passed  through  the  dif- 
ferent stages  from  the  large  motor  driving  the  entire 
mill  to  the  present  day  practice  of  a  motor  for  each  in- 
(iividual  machine. 

As  the  electrification  of  the  textile  mills  was  not 
attempted  to  any  extent  until  after  the  introduction  of 
the  polyphase  system  and  the  induction  motor,  poly- 
phase current  has  been  almost  universally  used  in  the 
textile  industi-y,  except  in  the  finishing  and  printing 
plants.  Constant  speed  is  required  by  most  of  the  ma- 
chinery in  the  mill  and  no  motor  meets  this  require- 
ment better  than  the  squirrel-cage  induction  motor. 
Its  simplicity  of  construction  and  operation  peculiarly 
adapts   this   motor   to   textile   service;   the   absence   of 


by  a  number  of  smaller  motors  driving  groups  of  ma- 
chines in  the  diflferent  departments,  thus  not  only  re- 
ducing the  line  shafting  but  also  obtaining  independ- 
ence of  operation  in  each  department.  It  soon  de- 
veloped that  motors  of  standard  design  would  not  meet 
the  operating  conditions  and  the  two  troublesnme  fac- 
tors first  encountered  were  lint  and  humidity,  the  first 
a  natural  bv-product  of  the  processes  and  the  second  a 
necessary  condition  for  the  proper  working  of  the  tex- 
tiles The  lint  consists  of  small  cotton  or  woolen  fibres 
thrown  from  the  materials  as  they  are  worked  through 
the  different  processes,  and  is  held  in  suspension  in 
large  quantities  in  the  air  in  the  mill.  The  lint  is  car- 
ried by  the  air  currents  and  not  only  finds  its  way 
jh rough  every  crevice,  but  is  deposited  on  all  rough 
surfaces.     This  lint  is  drawn  into  the  motors  by  the 


November,  1921 


THE   ELECTRIC  JOURNAL 


495 


ventilating  air  and,  clings  to  the  windings  and  rough 
surfaces  and,  where  the  air  passages  are  small,  in  a 
short  time  clogs  the  ventilating  system,  causing  the  mo- 
tors to  overheat.  Fortunately  the  motors  used  in  group 
drive  are  large,  ranging  in  sizes  from  50  to  150  hp,  and 
therefore  have  large  and  accessible  air  passages  that 
do  not  clog  quickly  with  the  lint  and  can  easily  be 
cleaned.  These  troubles  from  lint  then  are  not  so 
serious  in  the  large  motors  but  have  resulted  in  the  use 
of  liberally  rated  motors  rather  than  in  means  of  ex- 
cluding the  lint. 

The  lint  makes  trouble  in  another  way,  by  work- 
ing its  way  into  the  bearing  housings  of  the  motor  and 
interfering  with  the  oiling  system.  In  motors  of  this 
size,  it  is  necessary  to  use  bearings  of  the  ring  oiling 
type  and  the  lint  not  only  clogs  the  oil  grooves  and 
drains,  but  in  many  cases  prevents  the  turning  of  the 
oil  rings.  Further,  it  forms  in  streamers  that  dip  into 
the  oil  and  hang  from  the  openings  in  the  housing; 
these  act  like  wicks  to  syphon  the  oil  from  the  reser- 
voir. Dripping  oil  is  not  only  very  undesirable  in  a 
mill  handling  fine  textiles  but,  together  with  a  clogged 
oiling  system,  results  in  too  frequent  oiling  or  burnt 
out  bearings.  To  meet  this  condition  the  dust  proof 
bearing  has  been  developed.  In  this  type  of  bearing 
all  openings  and  joints  are  sealed  with  felt  gaskets;  a 
felt  pad  is  placed  under  the  oil  hole  cover  and  felt  gas- 
kets reinforced  with  steel  washers  are  attached  to  the 
ends  of  the  housing  fitting  snugly  around  the  shaft. 
The  overflow  plug,  which  maintains  the  oil  level  at  the 
proper  height  in  the  reservoir,  is  provided  with  an  over- 
hanging hinged  cover  with  a  clearance  that  is  sufficient 
to  allow  the  oil  to  overflow,  but  yet  small  enough  that, 
with  the  overhanging  feature,  the  lint  cannot  reach  the 
oil  chamber.  The  opening  in  the  overflow  is  made 
large  to  permit  the  filling  of  the  bearing  through  it  so 
that  it  is  not  necessary  to  open  the  oil  hole  cover  in  the 
top  of  the  bearing  housing  except  for  inspection. 

The  humidity  in  the  mill  is  maintained  at  a  con- 
stant value  by  artificial  humidifiers  and  this  moisture 
finds  its  way  into  the  insulation  of  the  motor  windings. 
The  voltage  almost  universally  used  in  textile  mills  is 
550  volts,  the  highest  permissible  with  so-called  low- 
voltage  motors.  The  standard  insulation  is  working 
up  near  the  limit  for  which  it  is  designed,  and  any  de- 
terioration in  its  insulating  qualities  due  to  moisture 
soon  results  in  a  failure.  The  effect  of  the  humidity  is 
not  so  serious  when  the  motors  are  running,  as  the  heat 
produced  in  them  prevents  the  penetration  of  the  mois- 
ture into  the  windings;  but  when  the  motors  are  shut 
down  for  a  sufficient  period  to  allow  them  to  cool  off, 
as  IS  the  case  over  night  or  Sunday,  the  moisture  pene- 
trates the  insulation.  Experience  has  shown  that  with 
motors  not  properly  insulated  for  textile  service  most 
of  the  burn  outs  occur  on  Monday  morning  or  after 
periods  of  shut  down.  To  overcome  the  effects  of  the 
humidity,  the  windings  in  motors  for  textile  service  are 
specially  insulated  and  treated  with  moisture  resisting 


compounds,  and  thousands  of  motors  so  insulated  have 
proven  the  adequacy  of  this  method. 

The  dust  proof  bearings  and  textile  insulation  are 
features  of  all  present-day  textile  motors.  No  special 
electrical  characteristics  are  required  for  motors  for 
group  drive  as  it  does  not  differ  essentially  from  line 
shaft  drive  in  other  industries.  The  motors  are  re- 
quired to  start  only  the  line  shafting,  and  therefore  re- 
quire no  special  torque  characteristics. 

The  group  drive  demonstrated  the  advantages  of 
electric  motor  drive ;  the  improvement  in  the  product 
due  to  uniformity  in  the  speed  of  the  machines,  the 
elimination  of  some  line  shafting,  the  separation  and 
independence  of  departments  and  the  ease  of  expan- 
sion were  apparent  in  the  motor  drive,  and  led  to  steps 
to   further  take  advantage  of  its  possibilities.     Conse- 


FIG.    I — INSTALLATION  OF  FOUR  FRAME  DRIVE   MOTORS 

quently  the  so-called  "four-frame  drive"  was  developed 
for  spinning,  roving  and  twisting  frames.  These 
frames  are  placed  in  the  mill  in  rows  and  lend  to  an 
arrangement  of  four  machines  to  a  group.  By  placing 
the  driving  pulleys  of  the  four  machines  in  the  same 
alley,  they  come  in  a  position  to  permit  belting  them  to 
two  double  crown  pulleys  on  one  motor,  mounted  on 
the  ceiling  as  shown  in  Fig.  i.  The  frames  are  pro- 
vided with  tight  and  loose  pulleys  and  are  started  and 
stopped  by  shifting  the  belts  from  the  loose  to  the  tight 
pulley  and  vice  versa.  The  motor  therefore  runs  con- 
tinually and  starts  without  load  on  the  loose  pulleys. 
As  the  slip  or  speed  regulation  and  the  starting  tor- 
Cjue  of  an  induction  motor  are  inter-dependent,  a  re- 
duction in  the  starting  torques  gives  a  corresponding 
reduction  in  the  slip  which  means  improved  speed 
regulation.  Every  percent  decrease  in  slip  represents 
the  same  percentage  increase  in  efficiency.     The   four 


496 


THE    ELECTRIC   JOURNAL 


Vol.  XVlII,  No.  II 


frame  drive  motor  is  designed  to  give  low  starting  tor- 
que with  the  resultant  improvement  in  the  speed  regu- 
lation and  the  efficiency.  Good  speed  regulation  is 
very  desirable  in  this  type  of  motor  on  account  of  the 
fact  that  it  must  operate  at  ^,  J^,  ^  and  full  load  as 
one,  two,  three  or  four  frames  are  thrown  on  it,  and  a 
minimum  variation  in  the  driving  speed  with  this  varia- 
tion in  load  is  required.  These  motors  range  in  size 
from  15  to  30  hp,  operating  at  speeds  of  1170  and  1760 
r.p.m.  and  have  a  high  power-factor..  For  many  years 
motors  operating  at  1760  r.p.m.  were  used  and  experi- 
ence shows  that  this  high  speed  was  responsible  for 
much  of  the  trouble  early  encountered  with  these  mo- 
tors. Any  unbalancing  in  the  pulleys  at  this  high  speed 
lesulted  in  severe  high  frequency  vibration  that  in  time 
crystallized  and  wrecked  certain  parts  of  the  motors 
and  mountings.  Small  pulleys  are  required  on  the  mo- 
tor at  the  high  speed,  giving  small  area  of  belt  con- 
tact, making  it  necessary  to  use  excessive  belt  tension 
to  prevent  slippage;  and  further,  the  smaller  the  pulley 
the  greater  the  jolt  caused  by  the  belt  splice  passing 
over  it.  Motors  operating  at  1170  r.p.m.  are  now  used 
for  four  frame  drive  and  greatly  improve  the  operating 


FIG.    2 — UNIVERS.VL-TYl'E   FOUR    FRAME    DRIVE    MOTOR 

condition  by  reducing  the  vibration,  and  increasing  the 
Size  of  the  pulleys,  resulting  in  lower  belt  tension,  with 
increased  life  for  the  belts  and  bearings. 

As  the  pulls  of  the  four  belts  are  at  different 
angles  no  means  of  shifting  the  motors  to  adjust  the 
belt  tension  can  easily  be  provided.  To  take  care  of 
this  condition  and  avoid  frequent  tightening  and  re- 
splicing,  the  belts  are  cut  shorter  than  is  standard  prac- 
tice making  them  tight  enough  to  take  care  of  future 
stretching.  This  results  in  heavy  belt  tension  that  has 
made  it  necessary  to  use  bearings  2.5  in.  diam.  by  six 
in.  length  in  the  motors.  This  tension,  together  with 
\he  high  speed,  necessitates  the  use  of  ring  oiling  bear- 
ings instead  of  the  waste  packed  type.  The  heavy  belt 
tension  also  demands  very  rigid  mountings  for  the  mo- 
tor, not  only  to  resist  the  steady  pull  but  also  to  re- 
duce the  vibration  caused  by  the  belt  splices  passing 
over  the  pulleys. 

The  size  of  these  motors  is  such  as  to  require  that 
the  motor  design  take  into  consideration  the  lint  which 
is  carried  into  the  motor  by  its  ventilating  fans.  The 
use  of  screens  has  been  tried  on  four  frame  drive  mo- 
tors, but  with  little  success,  due  to  the  inaccessibility 
for  properly  cleaning  the  screens  and  to  the  inadapta- 


bility for  obtaining  sufficient  screen  area  to  admit 
enough  air  when  a  thin  blanket  of  lint  collects  on  the 
screen.  To  take  care  of  the  lint  the  motors  are  de- 
signed without  radial  air  ducts  through  the  cores;  and 
with  large  clearances  between  the  windings  and  end 
brackets  to  allow  the  lint  to  pass  through  and  not  ac- 
cummulate  in  sufficient  quantity  in  a  reasonable  time 
to  clog  the  air  passage.  By  making  tlie  end  brackets 
with  large  openings  and  eliminating  air  shields  and  de- 
flectors, the  interior  of  the  motor  is  accessible  for 
weekly  cleaning  without  disturbing  the  motor  and,  in 
mills  where  compressed  air  is  available  for  cleaning, 
only  a  few  minutes  are  required  to  blow  out  the  mo- 
tors; or,  where  air  is  not  available,  the  openings  are 
large  enough  to  admit  the  hand  for  the  removal  of  the 
lint. 

The  four  frame  drive  motor  is  built  in  two  dis- 
tinct types  to  take  care  of  different  aisle  spacings  in  the 
mill ;  namely,  the  "double  extended  shaft  type"  and  the 
"universal  type." 

Where  the  aisle  spacing  is  such  as  to  allow  a  mo- 
tor to  be  placed  between  the  two  double  crown  pulleys 
v>ithout  an  excessive  overhang  of  the  pulleys,  the 
I'luble  extended  shaft  type  shown  in  Fig.  i  is  used. 
W  here  the  aisle  spacing  is  too  small  to  permit  this,  the 
universal  type  is  used.  Many  different  arrangements 
have  been  devised  for  this  motor,  but  the  three  bear- 
ing arrangement,  shown  in  I-'ig.  2,  has  been  found  best 
-uited  to  the  requirements.  This  outfit  has  two  bear- 
ings on  the  motor  and  a  third  bearing  at  the  outer  end 
nf  a  46  in.  shaft  extension  that  is  solid  without  a  coup- 
ling. The  middle  bearing  is  three  inches  in  diameter 
.  nd  it,  together  with  its  supporting  bracket,  is  split  to 
permit  the  replacement  of  the  bearing  without  disturb- 
ing the  other  parts  of  the  outfit.  The  outside  motor 
hearing  is  smaller,  as  it  only  maintains  the  rotor  con- 
centric with  the  stator  and  carries  very  little  load. 
With  the  two  brackets  mounted  directly  on  each  end 
of  the  motor  there  is  no  chance  for  the  rotor  to  rub 
the  stator  unless  the  bearings  wear  down ;  a  deflection 
in  the  shaft  extension  is  not  transmitted  to  the  rotor, 
which  is  held  rigidly  in  place  by  the  outside  bracket. 
The  diameter  of  the  shaft  that  carries'  the  pulley  is 
three  inches  and  is  ample  to  take  care  of  the  heavy  belt 
tension  encountered  in  this  service.  Two  keyway-;, 
180  degrees  apart,  are  cut  in  the  shaft  to  overcome  the 
unbalancing  caused  by  one  keyway  and  key. 

In  order  to  take  care  of  slight  variations  in  align- 
ment and  small  deflections  in  the  shaft,  the  pedestal 
bearing  at  the  end  of  the  shaft  extension  is  provided 
with  a  self-aligning  type  of  bearing.  This  self-align- 
ing feature  has  overcome  the  difficulties  first  encoun- 
tered with  the  inounting  and  operation  of  the  three- 
bearing  outfit  with  solid  bearings.  The  pedestal  sup- 
porting this  bearing  is  equipped  with  a  separate  steel 
plate  under  its  base  with  the  mounting  bolt  holes  in  this 
plate  spaced  the  same  as  those  in  the  motor  feet.  The 
pedestal  is  bolted  to  this  plate  with  sufficient  clearance 


November,  1921 


THE  ELECTRIC  JOURNAL 


497 


in  the  bolt  holes  to  permit  ]&  in.  adjustment  after  the 
plate  is  rigidly  bolted  in  place,  to  provide  a  means  of 
alignment  parallel  to  the  base ;  and  with  a  clearance  be- 
tween the  plate  and  the  base  to  take  shims  for  adjusting 
the  alignment  at  right  angles  to  the  base.  Once  a 
proper  alignment  of  the  pedestal  is  obtained,  it  can  be 
dowelled  to  the  plate  and,  in  case  it  is  necessary  to  re- 
move the  pedestal,  this  can  be  done  without  removing 
the  plate  and  disturbing  the  alignment,  which  will  be 
again  maintained  when  the  pedestal  is  put  in  place  and 
the  dowel  pins  driven  home.  Many  motors  of  this 
t^-pe  are  in  service  and  giving  very  satisfactory  opera- 
tion. 

Where  the  aisle  spacing  is  so  wide  that  the  pulleys 
must  be  mounted  too  far  from  the  bearings  on  the 
double  extended  shaft  type,  a  modification  of  the  uni- 
versal type  is  used  consisting  in  a  shaft  extension  on 
the  end  opposite  the  pedestal  end  of  the  outfit.  One 
I'uUey  is  then  mounted  on  this  extra  shaft  extension 
?nd  the  other  on  the  shaft  near  the  pedestal. 

In  some  cases  only  two  frames  instead  of  four 
are  driven  by  the  one  motor,  giving  what  is  known  as 
two-frame-drive.  This  requires  a  motor  of  half  the 
horse-power  rating  used  for  four  frames  and  with 
single  or  double  shaft  extension  of  either  type  depend- 
ing on  whether  the  frames  are  placed  side  by  side  or 
end  to  end. 

Each  step  toward  the  ultimate  of  individual  motor 
drive  was  justified  by  the  advantages  obtained  and 
demonstrated  that  still  further  advantages  were 
possible  by  mounting  the  motors  directly  on  each  ma- 
chine. Individual  motor  drive  has  now  established  its 
superiority  and  has  been  adopted  for  the  greater  per- 
centage of  the  machines,  in  up-to-date  mills  and  is 
recognized  by  the  machinery  builders  as  the  future 
drive  for  textile  machinery. 

To  take  advantage  of  all  the  possibilities  of  in- 
dividual drive,  the  motor  must  be  designed  to  meet  the 
requirements  of  the  machine  to  be  driven  exactly  and 
this  has  lead  to  dilTerent  types  of  motors  for  different 
kinds  of  machines. 

As  approximately  50  percent  of  the  power  re- 
quired in  a  textile  mill  is  used  in  the  spinning  and 
twisting  processes,  the  spinning  and  twisting  frames 
were  among  the  lirst  to  receive  attention  in  the  de- 
velopment of  the  individual  motor.  The  spinning 
frame  motors  are  mostly  of  5  hp,  and  7.5  hp  sizes, 
while  those  for  twisting  frames  may  run  as  high  as  15 
hp  for  large  tire  cord  twisters.  The  motor  speed  is 
1750  r.p.m.  for  all  these  frames,  with  the  exception  of 
the  large  twisters,  for  which  1160  r.p.m.  is  more  suit- 
able. The  power  required  to  drive  these  frames  is 
practically  all  used  to  overcome  the  friction  of  the 
numerous  bearings  and  small  belts  or  tapes;  at  stand- 
still, therefore,  with  the  lubrication  stifif  and  not  fiow- 
mg,  the  static  friction  is  high,  demanding  heavy  start- 
ing torques.  The  starting  conditions  are  the  heaviest 
after  the   machines  have  been   shut  down   a   sufficient 


length  of  time  to  allow  the  lubricant  to  stiffen,  as  is  the 
case  after  the  machines  have  stood  over  night.  The 
motors  must  have  ample  starting  torque  to  meet  this 
condition.  One  of  the  early  predicted  objections  to 
individual  motor  drive  was  the  breaking  of  the  yarn, 
due  to  too  rapid  acceleration  of  the  frames  in  start- 
ing; this  prediction  was  not  fulfilled  to  any  extent  in 
practice,  largely  on  account  of  the  consideration  given 
to  it  in  designing  and  applying  the  motors.  It  is  seen 
then  that  the  starting  characteristics  of  the  motor  must 
be  just  right,  for  too  low  a  torque  will  not  start  the 
frame  and  too  high  a  torc|ue  will  result  in  broken  ends. 
Much  experience  and  field  development  has  been  neces- 
sary to  determine  the  starting  characteristics  now  used 
in  the  spinning  and  twisting  frame  motors. 

To  obtain  this  high  starting  torque  and  yet  not 
sacrifice  efficiency,  the  motors  are  carefully  designed 
to  give  the  best  distribution  of  losses;  and  full  load 
etiiciences  of  86  to  88  percent-  are  obtained.     As  the 


^  ^: 


FIG.   3 — INDIVIDUAL    MOTOR   DRIVE   ON    SPINNING    .\ND    TWISTING 
FR.\MES 

power-factor  of  an  induction  motor  increases  as  the 
number  of  poles  decreases,  these  motors  which  are 
mostly  four  and  some  six  poles  have  a  high  power- 
factor,  ranging  around  90  percent  at  full  load. 

Different  methods  of  connecting  the  motors  to  the 
frames  are  used.  In  some  of  the  early  drives,  the 
motors  were  mounted  on  the  floor  and  belted  to  the 
driving  pulley  on  the  cylinder  shaft.  This  is  not  very 
satisfactory,  as  it  does  not  eliminate  the  belt  slippage 
which  is  one  of  the  possible  advantages  of  individual 
drive ;  and  further  the  short  pulley  centers  result  in 
small  arc  of  belt  contact  on  the  motor  pulleys,  requir- 
ing heavy  belt  tension  to  pre\-ent  slippage  with  result- 
ant bearing  troubles. 

The  speed  of  the  driving  cylinder  is  approxi- 
mately the  same  as  that  of  a  six-pole,  60  cvcle  motor, 
that  is,  1 150  r.p.m.  and  lends  to  the  direct  connection 
of  the  motor  to  the  cylinder  shaft  but,  on  account  of 
the  variation  in  the  spindle  speed  i-equired  for  the  spin- 
ning of  different  yarns,  the  constant  speed  induction 
motor  will  not  meet  the  requirement.  This  is  an  ideal 
form  of  drive  and  ofifers  a  field  of  application  for  the 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


variable  speed  alternating-current  motor.  A  recent 
trial  installation  at  the  Mason  Tire  &  Rubber  Com- 
pany, Kent,  Ohio,  of  a  variable  speed  induction  motor 
of  the  wound-rotor  type  has  been  very  successful.  The 
motor  is  direct  connected  to  the  cylinder,  the  motor 
bearing  replacing  the  outer  cylinder  bearing,  and  is 
operated  through  a  controller  that  gives  instantaneous 
speed  variation  in  small  steps.  With  this  speed  varia- 
tion, the  spinning  frame  can  be  instantaneously  ad- 
justed to  meet  varjing  atmospheric  conditions  in  the 
mill  and  variations  in  the  raw  material.  The  in- 
creased cost  of  the  motor  and  controller  and  the  re- 
duction in  efficiency  at  reduced  speeds  are  balanced  by 
the  elimination  of  the  first  cost  and  upkeep  of  chains 
and  gears  and  the  improvement  in  the  product. 

Spur  gearing  is  used  for  connecting  the  motor  to 
the  cylinder  shaft  and  has  the  advantages  of  a  posi- 
tive drive  and  the  variation  in  speed  by  changing  the 
gear  ratios,  but  has  the  disadvantage  of  the  lack  of 
flexibility. 

The  chain  is  now  recognized  as  the  best  means  of 
connecting  the  induction  motor  to  the  cylinder  shaft; 
it  gives  a  positive  drive  with  a  variation  in  speed  ob- 
tainable by  changing  to  different  sized  sprockets,  and 
possesses  considerable  flexibility  with  the  elimination 
of  much  of  the  vibration  found  in  the  gear  drive.  The 
slight  amount  of  slack  in  the  chain  allows  the  motor 
to  rotate  a  small  amount  before  encountering  the  load, 
thus  improving  the  starting  condition.  The  motors 
are  furnished  with  tapered  shafts  and  nuts  to  take  the 
chain  sprockets.  Recently  the  machinery  builders  and 
chain  and  motor  manufacturers  have  standardized  the 
sizes  of  sprockets  and  motor  and  machine  shaft  exten- 
sions for  all  sizes  of  motors  and  frames.  The  method 
cf  mounting  the  motor  on  the  spinning  frame  bracket 
and  the  means  of  alignment  have  also  been  standard- 
ized. A  guide  strip  inserted  in  the  motor  feet  and 
sliding  in  a  groove  in  the  mounting  brackets  main- 
tains a  definite  alignment  of  the  motor  with  the  cylin- 
der shaft  and  yet  permits  of  adjustment  by  jack 
screws  to  take  up  the  slack  in  the  chain  for  diff'erent 
sizes  of  sprockets. 

The  size  of  these  motors  is  such  that  the  air  pass- 
ages are  small  and  easily  clogged,  making  it  necessary 
to  provide  means  for  excluding  the  lint.  Two  effec- 
tive means  for  the  exclusion  of  the  lint  are  employed 
on  individual  motors;  first,  totally  enclosing,  and  sec- 
ond, screening  the  air  inlets.  The  totally  enclosed  mo- 
tor is  the  latest  development  in  the  lint  proof  type,  but 
the  larger  the  motor  the  more  expensive  this  feature 
becomes.  In  the  open  motor,  the  heat  produced  is 
carried  away  by  the  air  passed  through  it  by  the  ven- 
tilating fans,  but  in  the  totally  enclosed  motor  all  the 
heat  must  be  dissipated  into  the  atmosphere  from  the 
external  surface  by  natural  convection.  The  area  of 
the  external  surface  of  a  motor  does  not  increase  nearly 
as  rapidly  as  its  horse-power  capacity  on  an  open  basis, 
so  that  the  size  of  a  totally  enclosed  motor  increases 


much  more  rapidly  with  increased  horse-power  than 
that  of  the  open  motor.  Enclosed  motors  of  5,  7.5 
and  10  hp  require  frame  sizes  suitable  for  10,  15  and 
25  hp,  respectively,  as  open  motors,  making  the  en- 
closed type  expensive.  This  expense  is  not  justified 
by  the  advantages  offered  over  other  less  expensive 
types,  with  the  result  that  enclosed  motors  are  not  used 
to  any  extent  for  spinning  and  twisting  frame  drives. 
Screens  placed  over  the  motor  bracket  openings" 
through  which  the  ventilating  air  enters  the  motors,  are 
verj'  effective  for  removing  the  lint  from  the  air. 
The  lint,  however,  collects  in  a  blanket  on  the  screen 
and  in  time  this  blanket  becomes  so  heavy  that  the 
screen  is  completely  clogged  and  the  motor,  robbed  of 
its  ventilation,  overheats.  But  if  the  screens  are 
cleaned  once  or  twice  a  day,  the  accumulation  of  iint 
does  not  become  heavy  enough  to  cause  trouble.  The 
motors  for  individual  drive  are  mounted  near  the  floor 
j.nd  are  easily  accessible  for  the  cleaning  of  the  screens 
by  the  machine  operators,  and  are  therefore  well 
adapted  to  the  use  of  screens. 

Manv  different  kinds  of  screens  have  been  used 
;ind  much  experimenting  under  service  conditions  has 
been  required  to  determine  the  most  effective  type. 
W'ire  screens  of  different  mesh  have  been  tried  but 
have  not  been  altogether  satisfactory;  the  fine  meshes 
(30  to  60  per  inch),  in  time  clog  up  with  oil  and  dust 
and  cannot  be  wiped  clean,  and  the  coarser  meshes 
allow  the  ends  of  the  lint  fibres  to  pass  through  and 
wind  around  the  wires,  forming  a  blanket  that  is  inter- 
woven with  the  screen  and  is  very  difficult  to  remove 
and  in  time  results  in  a  clogged  screen. 

.\  screen  made  of  perforated  sheet  metal  with 
3/32  in.  diameter  perforations,  seven  per  inch,  has  been 
found  to  meet  the  requirements  best  as  it  presents  a 
smooth  surface  and  is  easily  cleaned.  The  holes  are 
small  enough  to  prevent  the  lint  from  passing  through 
pnd  the  width  of  the  metal  between  holes  is  great 
enough  to  overcome  the  intertwining  of  the  fibres  with 
the  screen.  The  screens  are  attached  to  the  motors  in 
such  a  manner  that  they  can  easily  be  removed  and  are 
made  to  cover  the  entire  face  of  the  bracket  to  give  as 
large  an  area  as  possible.  Screens  are  now  standard 
equipment  on  all  spinning  and  twisting  motors,  and 
motors  equipped  with  the  perforated  metal  screens 
show  a  small  accumulation  of  lint  within  the  motor 
after  a  years  service.  Screened  motors  should  be 
taken  apart  and  cleaned  about  once  a  year. 

Ring  oiling  bearings  were  used  in  individual  tex- 
tile motors  for  manv  years  but  gave  trouble,  due  first, 
to  the  lint  gradually  finding  its  way  into  the  housmgs 
and  either  svphoning  the  oil  from  the  reservoir  or  clog- 
ging the  oil  grooves;  and  second,  to  the  rapid  evapora- 
non  of  the  oil  caused  by  the  continual  agitation  of  the 
oil  by  the  oil  rings.  In  the  smaller  motors,  the  oil  reser- 
voir is  small,  and  for  this  reason  a  loss  of  oil  from  lint 
or  evaporation  is  much  more  troublesome  than  in 
larger  motors. 


November,  192 1 


THE   ELECTRIC  JOURNAL 


499 


The  waste  packed  bearing  in  which  the  oil  is  held 
in  wool  waste  packed  into  the  bearing  housing  and  fed 
to  the  bearing  by  the  wick  action  of  the  waste,  is  well 
adapted  to  the  speeds  and  small  torques  of  these  mo- 
tors, and  has  established  its  superiority  over  the  ring 
oiling  bearing  for  overcoming  the  troubles  above 
mentioned.  The  waste,  which  is  not  much  more  than 
a  bundle  of  lint,  is  not  affected  by  the  addition  of  a 
little  more  lint,  and  further  there  is  no  free  oil  in  the 
bearing  housing.  In  order  to  allow  the  oil  soaked 
waste  to  come  in  contact  with  the  shaft,  the  bearing 
has  an  opening  in  the  one  side  extending  about  one 
half  its  length  and  one  third  its  circumference.  To 
avoid  having  the  thrust  of  the  shaft  against  this  side  cf 


FIG.    4 — INDIVIDUAL    MOTOR    DRIVE    FOR    LOOMS 

the  bearing  (with  the  opening),  it  is  necessary  to  as- 
semble the  bearing  so  that  the  opening  is  on  the  op- 
posite side  from  the  direction  of  the  thrust. 

To  facilitate  the  assembly  to  take  care  of  the  dif- 
ferent directions  of  the  thrust  the  one  motor  bracket  is 
assembled  with  the  opening  in  the  bearing  on  the  side 
opposite  to  that  of  the  other  bracket.  Then  to  ar- 
range the  motor  for  a  thrust  opposite  from  that  for 
which  it  was  originally  assembled,  it  is  only  necessary 
to  interchange  the  rear  and  front  brackets.  With  this 
arrangement  the  thrust  on  the  bearing  on  the  end 
opposite  from  the  drive  end  is  against  the  opening,  but 
this  thrust  is  so  small  compared  to  the  thrust  on  the 
drive  bearing  that  there  is  sufficient  bearing  surface  to 
take  care  of  it.  To  make  these  bearing  housings  as 
tight  as  possible  the  drain  and  overflow  plugs  are 
omitted. 


The  switches  for  operating  the  motors  are 
mounted  on  the  ends  of  the  spinning  frames  in  such  a 
manner  that  leads  from  three  to  five  feet  in  length  will 
reach  from  the  motor  to  the  switch,  consequently  the 
motor  leads  are  made  5  ft.  long  to  avoid  making  splices 
at  the  motor.  The  leads  are  carried  in  flexible  conduit 
and  the  motors  are  provided  with  squeeze  connectors 
for  attaching  this  conduit. 

From  the  forgoing  it  is  seen  that  a  motor  has  been 
developed  to  meet  the  requirements  of  spinning,  roving 
and  twisting  frames  to  the  last  detail. 

A  further  step  in  the  individual  drive  of  spinning 
and  twisting  frames  is  the  use  of  a  small  motor  on  each 
spindle.  Some  experimental  work  has  been  done  along 
this  line,  but  has  not  so  far  resulted  in  a  practical  ap- 
plication. The  horse-power  required  ranges  from  1/50 
on  spinning  frames  to  1/20  on  large  twisters.  These 
small  motors  are  very  inefficient  and  it  is  a  question  as 
to  whether  the  advantages  gained  by  the  elimination  of 
the  cylinder  and  tapes  will  warrant  this  low  efficiency. 
Another  factor  is  the  high  spindle  speed,  which  is  much 
above  that  obtainable  with  a  60  cycles  induction  mo- 
tor and  means  either  the  use  of  frequency  changer  sets 
or  the  commutator  type  of  motor. 

For  driving  pickers  a  motor  identical  with  that 
for  spinning  is  used  with  the  exception  that  a  straight 
shaft  extension  is  provided  to  take  a  pulley ;  and  a  con- 
duit box  to  permit  the  splicing  of  the  long  leads  at  the 
motor  replaces  the  squeeze  connector.  For  the  double 
beater  type  of  picker  in  many  cases  two  motors,  one 
on  each  side  of  the  "A"  frame  are  used,  interconnected 
electrically  to  operate  as  one  motor.  In  other  cases  a 
ringle  motor  of  double  the  horse-power  rating  is  used 
with  a  third  pedestal  type  bearing  mounted  on  the 
opposite  end  of  the  A-frame  from  the  motor.  The 
shaft  extension  on  the  outside  end  of  the  motor  carries 
the  pulley  to  drive  the  one  beater;  and  the  long  shaft 
coupled  to  the  other  end  of  the  motor  is  supported  by 
the  third  bearing  extending  far  enough  beyond  the 
pedestal  to  take  the  pulley  to  drive  the  second  beater. 
This  is  not  as  satisfactory  a  mechanical  arrangement  as 
the  two  motor  scheme. 

The  loom  motor  has  become  very  popular,  and  is 
as  extensively  used  as  the  spinning  types,  due  largely 
to  the  desirable  uniformity  in  speed  obtained  by  the  in- 
dividual motor  drive  on  the  looms.  The  motions  of  a 
loom  are  reciprocating,  and  the  torque  variable  over  a 
cycle,  resulting  in  a  variable  load  on  the  motor  and  no 
small  amount  of  vibration,  demanding  a  motor  of 
rugged  construction.  The  speed  of  the  loom  is  low, 
and  as  the  motor  is  geared  to  the  main  driving  gear,  a 
small  pinion  is  necessary  on  the  motor  shaft  to  give  the 
reduction  from  motor  speeds  of  1160  and  1750  r.p.m. 
This  gear  drive  requires  a  tapered  shaft  extension  on 
the  motor,  and  relatively  large  substantial  bearings  to 
withstand  the  pounding  from  the  gears  and  the  varia- 
tion in  load.  To  meet  this  requirement  bronze  bear- 
i;igs  of  the  waste  packed  type  are  used.  The  bearings 
with    their    supporting   brackets    are    so    arranged  that 


Soo 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


they  can  be  turned  through  360  degrees  in  steps  of  90 
degrees  for  floor,  wall  or  ceiling  mounting,  with  the 
opening  in  the  proper  position  for  the  thrust  from  the 
pinion. 

Two  methods  of  connecting  motors  to  the  looms 
are  employed ;  in  one  case  the  motor  and  gear  are 
rigidly  connected  to  the  driving  shaft,  while  in  the 
other  a  friction  clutch  is  inserted  between  the  large 
gear  and  the  driving  shaft.  In  the  first  case  the  motor 
starts  and  stops  with  the  loom,  and  must  have  a  large 
starting  torque  to  overcome  the  bearing  friction  and 
inertia  of  the  moving  parts;  the  high  torque  loom  mo- 
tor is  designed  to  give  this  torque  with  as  high  perform- 
ance as  possible.  In  the  second  case  the  motor  starts 
light  and  runs  continually ;  the  starting  and  stopping  of 
the    loom   is   preformed   by    the    clutch.     The    starting 


FIG.   5 — VERTICAL   MOTOR  FOK  DRIVING   SILK   SPI.NNKRS 

torque  of  the  motor  can  be  reduced  to  a  minimum,  as 
has  been  done  in  the  low  torque  type  of  loom  motor, 
which  therefore  has  slightly  better  performance  than 
the  high  torque  type. 

Looms  require  motors  ranging  in  size  from  one- 
third  hp  on  the  smallest  cotton  looms  to  three  hp  on 
large  carpet  looms.  Following  inversely  the  same  line 
of  reasoning  previously  given  for  enclosed  spinning 
motors,  it  is  seen  that  the  smaller  loom  motors  have 
relatively  large  external  surfaces  and  are  adapted  to 
totally  enclosing  without  increasing  the  frame  to  such 
a  size  that  its  cost  is  offset  by  the  advantages  obtained. 
Almost  all  loom  motors  are  totally  enclosed  and  are 
lint  proof  in  the  full  sense  of  the  word.  They  are  pro- 
vided with  squeeze  connectors  to  take  flexible  conduit 


for  the  leads  and  have  windings  treated  to  withstand 
the  humidity,  even  though  they  are  enclosed. 

There  are  no  installations  of  individually  driven 
cards  at  the  present  time,  the  group  drive  being  used 
entirely.  A  recent  trial  drive  has  demonstrated  that 
there  is  nothing  impossible  nor  very  special  in  the  de- 
sign of  a  motor  for  this  drive,  and  that  the  card  will 
scon  fall  in  line  with  the  other  machines  for  individual 
drive. 

All  that  has  been  previously  mentioned  has  applied 
more  directly  to  the  cotton  and  woolen  industries,  but 
the  silk  industry  has  also  received  its  share  of  consid- 
eration in  the  development  of  individual  drive  motors. 
Many  of  the  special  features  required  for  the  cotton 
and  woolen  mills  apply 'also  to  the  silk  mill,  with  the 
exception  of  those  for  taking  care  of  the  lint.  The 
<-ilk  worm  is  a  very  expert  spinner  and  produces  a 
thread  that  does  not  throw  off  its  fibres  when  being 
worked  through  the  different  processes,  so  that  there 
is  no  lint  to  fly  in  the  air  in  the  silk  mill  to  bother  the 
motors. 

The  silk  spinning  and  twisting  frames  dift'er  from 
those  for  cotton  or  wool  in  that  the  driving  shaft  is  in 
a  vertical  instead  of  horizontal  position,  and  the  ver- 
tical motor  is,  therefore,  more  suitable  for  direct  con- 
nection to  the  vertical  shaft.  Horizontal  motors  have 
been  connected  through  bevel  gears  to  the  frames;  but 
ibe  loss  in  efficiency  and  vibration  in  the  gears  has 
been  a  serious  objection. 

The  special  vertical  motor  shown  in  Fig.  5  has 
lieen  developed  to  mount  in  the  end  frame  and  couple 
directly  to  the  driving  shaft  of  the  type  B  and  type  C 
.\twood  silk  spinners.  This  type  of  motor  is  built  in 
two  and  five  hp  sizes  at  870  r.p.m.  and  is  so  designed 
that  the  end  frame  of  a  spinner  of  either  a  new  or  ex- 
isting installation  can  be  set  onto  the  special  base  of 
the  motor,  and  the  motor  coupled  to  the  drive  shaft, 
v-ith  very  slight  modification  in  the  end  frame.  The 
height  of  the  motor  has  been  reduced  to  a  minimum. 
For  driving  other  types  of  spinners  that  are  not  adapted 
to  the  above  motors,  a  vertical  motor  with  a  pulley 
mounted  directly  on  a  shaft  extension  on  top  of  the 
motor  can  be  belted  to  the  vertical  drive  shaft. 

There  are  other  machines  in  the  textile  mills  that 
are  individually  driven  by  motors  and  not  been  men- 
tioned here,  but  the  special  features  of  the  motors  do 
not  differ  from  those  already  covered.  There  is  no 
reason  why  every  machine  in  a  textile  mill  cannot  be 
driven  successfully  and  better  than  before,  by  a  di- 
rect-connected electric  motor. 


taillvMual  Motor  "Orivo  cb: 


Spkiikg  niu 


1  wjster  i'lramo^ 


GEORGE  WRIGLEY 

Electrical  Engineer, 
J.  E.  Sirrine  &  Company,  Greenville,  S.  C. 


SPINNING  frames  are  machines  used  in  textile 
mills  for  reducing  the  prepared  raw  material  in 
the  form  of  a  soft  cord,  called  roving,  to  a  firm 
fine  thread  called  yarn.  They  perform  the  processes 
of  attenuation  and  spinning.  Practically  all  American 
yarns  are  spun  on  ring  frames.  In  these  frames  the 
bobbins  of  roving  are  placed  in  a  creel,  the  ends  carried 
through  rollers  running  at  successively  higher  speeds, 
through  proper  guides  and  thence  through  a  traveler 
to  the  spindle  bobbin.  The  traveler  is  a  small  metal 
loop  running  on  a  highly  polished  circular  track  called 
a  ring.  All  the  rings  of  a  frame  are  raised  and 
lowered  together  by  the  traverse  mechanism,  so  as  to 
wind  the  yarn  on  the  bobbins.  Generally  speaking, 
spinning  frames  carry  from  204  to  272  spindles. 

Twister  frames  are  very  much  like  spinning 
frames,  except  that  spools  of  yarn  instead  of  roving 
are  placed  in  the  creel  and  the  function  of  the  frame 
is  to  twist  two  or  more  of  these  yarns  together  so  as 
to  form  a  larger  and  stronger  yarn.  In  wet  twisters 
the  yarn  passes  through  a  water  bath  before  being 
twisted. 

Spinning  and  twister  frames  are  interesting  in 
that  they  embody  the  use  of  highly  perfected,  accur- 
ately balanced  spindles  running  at  speeds  of  approxi- 
mating 10  000  r.p.m. 

In  the  older  frames  the  spindles  are  driven  from 
a  tin  cylinder,  by  means  of  a  round  band.  In  the  new 
frames  the  spindles  are  driven  from  a  similar  cylinder 
by  a  flat  woven  tape,  using  one  tape  for  four  spindles. 
Uniform  tension  is  maintained  on  this  tape  by  means 
of  a  weighted  idler. 

In  earlier  installations  the  frames  were  driven 
from  water  wheels  or  engines  by  pulleys  and  belts. 
Large  group  electric  motors  were  next  used,  the  only 
material  gain  being  the  elimination  of  the  heavy  head 
shafting.  This  gain  was,  of  course,  offset  by  the  mo- 
tor losses.  The  next  system  was  to  use  one  motor 
with  shaft  extension  and  four  pulleys  to  drive  four 
frames.  All  of  these  drives  while  reasonably  satisfac- 
tory embodied  the  use  of  at  least  one  belt.  Counter- 
shafting  belts  show  a  slight  amount  of  slip  but  the 
real  offender  is  the  final  belt  from  the  shafting  or  four 
frame  motor  to  the  frame  pulley.  This  is  an  almost 
vertical  belt  exposed  to  oil  and  lint  and  in  spite  of 
daily  cleaning  will  show  an  appreciable  amount  of  slip. 
Each  decrement  of  speed  represents  at  least  a  corre- 
sponding decrement  of  production.  The  output  of  a 
frame  is  a  maximum  when  it  is  adjusted  and  equipped 


for  a  certain  proper  speed.  Any  decrease  in  speed 
will  cause  a  somewhat  greater  percentage  loss  of  pro- 
duction than  the  percentage  speed  change. 

Individual  motors  are  applied  to  spinning  and 
twister  frames  with  the  object  of  eliminating  belt  slip 
and  thereby  increasing  production.  The  general  ac- 
ceptance of  this  drive  was  delayed  due  to  the  lack  of  a 
satisfactory  connecting  transmission  between  the  motor 
and  the  driven  machine.  The  earlier  drives  used  di- 
rect connection  through  couplings.  In  some  cases 
rigid  couplings,  and  in  others  friction  clutches  were 


FIG.    I — SPINNING   FR.^MES   FORMERLY  DRIVEN   BY   BELTS   FROM   OVER- 
HEAD   SHAFTING 

Individual  motors  with  silent  chain  drive  were  installed 
without  moving  the  frames. 

used.  These  drives  did  not  allow  of  any  speed  adjust- 
ment, and  were  unsatisfactory,  principally  from  this 
standpoint.  For  direct  connection  it  is  generally  nec- 
essary to  use  1 150  r.p.m.  motors  which  are,  of  course, 
more  expensive,  less  efficient  and  bulkier  than  the  1750 
r.p.m.  motors. 

Following  the  direct-connected  drives,  spur  gear- 
ing was  tried,  and  such  materials  as  fibre,  raw  hide 
and  fabroid  were  used.  These  gears  proved  only  par- 
tially satisfactory,  and  generally  vibrated  badly, 
with  resulting  noise  and  rapid  wear. 

The  next  and  most  important  step  in  this  trans- 
mission was  the  use  of  the  so-called  silent  chains  on 
short    centers.      This    combination,    when    used    with 


502 


THE   ELECTRIC  JOURNAL 


Vol.  XMII,  No.  II 


rigid  cast-iron  supports,  has  proved  ver}-  satisfactory. 

The  standard  chain  drive  equipments  for  5  and 
7.5  hp  drives  are  2.5  to  3  in.  wide,  using  Yz  in.  pitch, 
9.5  or  10.5  in.  centers,  and  chain  speeds  approximating 
1500  ft.  a  minute.  Driving  sprockets  usually  carry  21 
teeth,  and  the  number  of  teeth  in  the  driven  sprockets 
is  varied  to  give  the  required  speed.  One  manufac- 
turer recommends  the  weekly  use  of  grease  for  the 
lubrication  of  his  drives,  and  another  recommends  the 
use  of  an  oil  bath.  In  the  latter  case  a  disc  on  the 
driven  sprocket  dips  into  the  oil  and  throws  it  to  the 
top  of  the  casing,  from  which  it  drips  on  to  the  chain, 
providing  continuous  lubrication. 

The  requirements  of  practically  all  spinning 
frames  today  are  met  by  the  application  of  5  or  7.5  hp, 
1750  r.p.ni.  induction  motors.  Twister  frames,  de- 
pending on  the  size  of  the  frame  and  material 
handled,  require  from  5  to  20  hp  motors.  Ninety  per- 
cent of  all  the  motors  installed  would  be  either  five  or 
7.5  hp.  These  motors  differ  only  slightly  from  stand- 
ard induction  motors,  but  have  the  following  special 
features:- -The  shafts  are  tapered  and  provided  with 


The  oil  switches  are  sometimes  operated  by 
shipper  rods  and  sometimes  by  hand.  The  latter 
method  seems  to  be  increasing  in  favor.  Another  de- 
velopment is  the  use  of  a  magnetic  switch  controlled 
from  push  button  stations.  While  slightly  more  ex- 
pensive, this  forms  a  very  convenient  and  flexible 
method  of  control. 

Automatic  oil  circuit  breakers  are  hardly  justified 
for  the  protection  of  these  motors,  and  non-automatic 
switches  are  generally  used  in  connection  with  fuses. 
Obviously  these  fuses,  in  order  to  carry  the  starting 
current,  must  be  too  large  to  protect  the  motor  against 
overload.  As  a  matter  of  fact,  an  overload  develop- 
ing in  the  machine  is  a  very  unusual  thing,  and  the 
greatest  cause  of  motor  burn-outs  is  single-phasing. 
It  is,  therefore,  desirable  to  make  these  protective  fuses 
just  as  large  as  possible,  in  order  to  prevent  single- 
phasing.  Recently  the  insurance  companies  have 
approved  the  use  of  time  limit  fuses  which  will  carry 


FIG.    2 — I.\D1VIUU.\L   MOTOR  DKlVt  ul-    .NbW    .Sll.N.M.NG    FR.\MES 

nuts  and  lock  washers  for  the  proper  holding  and  easy 
removal  of  the  chain  sprocket.  Bearings  are  of  the 
waste  packed  type,  providing  a  sturdy,  easily  main- 
tained bearing  and  eliminating  the  possibility  of  trouble 
from  the  hanging  up  of  oil  rings.  Terminal  fittings 
and  extended  leads  are  provided  to  obviate  the  use  of 
joints  at  the  motor  terminals,  these  leads  being  long 
enough  to  reach  from  the  motor  to  the  controlling 
switch.  Screens  are  generally  provided  over  the  mo- 
tor heads  to  prevent  the  entrance  of  bulky  masses  of 
lint  or  other  foreign  matter. 

Standard  characteristics  for  these  individual  mo- 
tors are  3  phase,  60  cycle,  550  volts,  with  occasional 
mstallations  of  220  volts  and  special  installations  of 
25  and  40  cycles  or  2  phase  . 

In  nearly  all  cases  starting  conditions  are  normal, 
approximating  constant  torque  from  rest  to  full  speed. 
Simple  non-automatic  switches  are  generally  used,  and 
the  motors  are  connected  directly  to  the  line  in  start- 
ing. For  heavy  twister  frames  special  precautions, 
such  as  starting  compensators,  should  be  provided  to 
prevent  excessive  starting  torque  and  consequent 
breakage  of  the  driven  machine  parts. 


KIG.    3— INDlVinfAI.   MOTOR   I!       '     ■"■         '  M.    1  KAMES 

heavy  instantaneous  starting  currents,  but  will  safely 
blow  after  small,  continuously  applied  overloads,  and 
these  devices  will  probably  prove  to  be  the  best  protec- 
tion available.  It  is,  of  course,  essential  that  the 
frames  and  motors  be  properly  grounded  m  order  to 
avoid  accidents. 

So  far,  the  variable  speed  motor  has  not  been 
generally  accepted.  Its  cost  is  high  and  its  speed 
changes  with  varying  voltage.  Especially  with  pur- 
chased power,  this  condition  will  have  to  be  met  by 
the  installation  of  automatic  feedei  regulators,  which 
\,ill  in  turn  add  to  the  first  cost  of  installation. 

The  bogey  of  high  room  temperatures  is,  of 
course,  a  fallacy.  These  motors  are  just  as  efficient  as 
any  combinations  of  mechanical  or  group  motor  drive. 
Therefore,  the  total  number  of  heat  units  liberated  in  a 
o-iven  room  will  be  approximately  the  same.  Of 
course,  the  individual  motors  feel  warm,  as  their 
energy  losses  emanate  from  a  small  surface  and  withm 


November,  1921 


THE   ELECTRIC  JOURNAL 


503 


reach.  On  the  other  hand,  all  this  heat  rises  to  the 
ceiling  and  a  great  part  of  it  there  passes  out  of  the 
top  of  the  room,  whereas,  with  belt  drive  from  above, 
the  heat  is  fanned  down  to  the  lower  levels  of  the 
room.  The  efficiency  and  power-factor  guarantees  on 
5  and  7.5  hp  motors  made  by  one  manufacturer  are 
given  in  Table  I.  In  addition  to  the  main  advantage 
of  increased  production  are  the  advantages  of  greater 
cleanliness  and   far  better  lighting  of  the  room. 

Recently  steps  have  been  taken  by  the  several 
manufacturers  to  standardize  such  details  as  the  di- 
mensions of  motor  shafts,  feet  alignment  spline  and 
driven  shaft.  This,  it  is  hoped,  will  lead  to  consider- 
able economy  and,  possibly,  to  the  interchangeability 
of  parts. 

It  might  be  feared  that  installations  of  individual 
motor  drives  would  necessarily  operate  at  abnormally 
low  power-factors.     From  practical  experience  and  as 


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KIC.  4 — POWER  REQUIRED  FOR  DIFFERENT  PARTS  OF  SPINNING  FRAME 

The  results  are  averages  of  several  tests  made  on  a  Saco- 
Lowell  spinning  frame  having  224  tape  driven  spindles  with  30's 
yarn  warp  and  driven  by  a  7.5  hp,  1800  r.  p.  m.  motor. 

A — Cylinder  only,  0.569  hp  or  12.2  percent.  B — Cylinder  and 
traverse,  0.608  hp  or  13. 1  percent.  C — Cylinder,  traverse  and  one 
front  roll,  0.731  hp  or  15.75  percent.  D — Cylinder,  traverse  and 
two  front  rolls,  0.807  hp  or  17.4  percent.  E — 224  spindles  only, 
3.343  hp  or  72.2  percent.  F — Complete  frame  less  j-arn,  4.15  or 
89.6  percent.  G — Complete  frame,  4.64  hp  or  100  percent.  Travel- 
ers and  creel  only,  0,49  hp  or  10.4  percent. 

ti  result  of  a  number  of  tests  it  is  gratifying  to  say 
that  the  power-factors  of  these  installations  are  rea- 
sonably good,  averaging  between  79  and  85  percent, 
depending  on  conditions.  This  is  especially  interest- 
ing in  view  of  the  fact  that  frequently  7.5  hp  motors 
are  provided  on  spinning  frames  requiring  only  5  hp 
at  the  time  of  installation.  The  extra  motor  capacity 
is  provided  to  take  care  of  any  probable  change  in  the 
requirements  of  the  frame,  such  as  higher  speeds  or 
heavier  yarns. 

Records  of  motor  burnouts  show  low  costs  from 
this   source.     Generally   speaking,  a   mill   with   a   large 


installation,  say  of  200  spinning  frame  motors,  will 
burn  out  probably  two  to  six  motors  in  a  year.  Ordi- 
narily one  or  two  motors  are  carried  as  spares  and  a 
substitution  can  be  made  with  little  loss  of  time. 

Very  little  information  is  available  on  the  life  of 
individual  motors  in  this  service.     One  of  the  oldest 
TABLE  I— MOTOR  CHARACTERISTICS 


H.  P. 
Rating 

Efficiency 

Power-Factor 

yi  Load 

KLoad 

86 
86.5 

Full 
Load 

K  Load 

}i  Load 

Full 
Load 

5 
"•5 

84 
83 

86 
87.5 

73 

72 

83 

82 

87 
87.S 

installations  in  the  territory,  that  at  the  Anderson 
Cotton  Mills,  is  stil:  in  operation  and  the  motors  are 
apparently  good  foi  years  to  come.  They  are  now 
about  twenty-five  years  old.  Installations  of  five  to 
ten  years  age  show  very  little  depreciation. 

A  curve  made  from  actual  tests  is  shown  in  Fig. 
4  to  illustrate  the  power  taken  by  the  several  elements 
of  the  spinning  frame  and  the  frame  when  operating 
complete.  The  results  of  a  large  number  of  tests  show 
that  the  power  of  spinning  and  twister  frames  varies 
with  the  spindle  speed,  the  yam  number,  traveler 
weight  and  various  other  factors.  Also  with  such 
variables  as  band  tension,  viscosity  of  lubricant,  etc. 

The  growth  of  individual  motor  drive  in  the 
southeastern  territory  in  Fig.  5  is  probably  represen- 
tative of  the  total  growth  in  this  country.  About  13 
percent  of  the  spindles  are  individual  motor  driven, 
leaving  a  considerable  field  for  these  applications. 

It  is  difficult  to  make  any  definite  statement  as  to 
wh'at  increased  production  can  be  had  by  motor  drive 
over  belt  drive.  This  increase  would  depend,  not  on 
the  individual  motor  drive,  but  on  the  condition  of  the 
belt  drive  with  which  it  is  compared.     If  the  belts  have 


-2  000  000 

-I  500  000 

1 

-i  000  000 

^500  000 

n 

1907 

1908 

1909 

1910 

191. 

191J 

V! 

19U 

19)5 

191b 

1917 

1918 

1919 

1910 

FIG.   5 — INCREASE  IN  INDIVIDUAL   MOTOR-DRIVEN   SPINNING  AND 
TWISTER  SPINDLES  SINCE  I907,  IN  SOUTHERN  MILLS  ONLY 

been  exceedingly  well  maintained,  a  small  increase  only 
might  be  expected.  Increases  as  high  as  ten  percent 
have  been  reported,  but  conservatively  speaking,  an 
.iverage  of  five  percent  would  probably  be  fair. 


?/I©ii:ors  for  1 


l'iBJS:iUj}' 


jK^ 


WARREN  B.  LEWIS 

Consulting  Engineer, 
Providence,  R.  I. 


THE  adaptation  of  the  electric  motor  to  machines 
for  finishing  cotton,  and  cotton  and  silk  piece 
goods  presents  to  the  engineer  many  problems 
quite  apart  from  those  in  the  field  of  electrical  engi- 
neering. The  convincing  arguments  set  forth  for  the 
use  of  the  electric  motor  in  the  broad  field  of  manu- 
facturing apply  to  cotton  cloth  finishing  plants;  but 
they  are  not  the  strongest  arguments  which  ma}'  be 
used. 

The  electric  motor  is  applied  to  industrial  ma- 
chines for  one  or  both  of  two  reasons.  It  must  have 
been  proven  to  be  a  more  efficient  method  of  trans- 
mitting power  from  the  shaft  of  the  prime  mover  to 
the  shaft  of  a  machine,  or  its  advantages  as  to  speed 
regulation  and  control  must  bring  about  an  increased 
production  in  the  machine  to  which  it  is  attached,  di- 
rectly or  indirectly. 

To  state  the  advantages  of  the  electric  motor  in 
the  finishing  industry  as  a  transmitting  device  would 
be  but  to  repeat  what  has  been  written  on  the  subject 
during  the  last  ten  years;  but  its  qualifications  as  a 
money-making  device  in  that  industry  are  not  so 
familiar  to  designers  and  manufacturers  of  motors  as 
they  are  to  the  engineer  who  has  had  occasion  to  study 
in  detail  its  actual  effect  upon  the  production  and  eco- 
nomical operation  of  certain  classes  of  finishing  ma- 
chinery. 

In  cotton  cloth  finishing,  power  is  divided  into  me- 
chanical power  for  driving  machines,  power  for  pump- 
ing vast  quantities  of  water,  light,  heat  for  warming 
buildings,  and  heat  in  the  form  of  high  and  low-pres- 
sure steam  used  for  boiling  and  drying  operations. 

Roughly  speaking,  40  percent  of  the  steam  leaving 
the  boilers  will  be  used  in  the  form  of  high-pressure 
live  steam  and  60  percent  will  be  delivered  to  prime 
movers.  Of  this  60  percent,  one-half  will  ultimately 
drive  constant-speed  machines  and  one-half  variable- 
speed  machines. 

In  a  well-designed  plant,  all  of  the  heat  used  in 
producing  mechanical  power,  with  the  exception  of 
that  lost  by  radiation  and  through  condensation  in 
prime  movers,  can  be  recovered  and  used  in  the  pro- 
cesses, resulting  in  a  reduction  of  the  amount  of  live 
steam  taken  directly  from  the  boilers  for  process  pur- 
poses. The  average  finishing  plant  does  not  run  in  any 
such  ideal  way;  but  w^astes  a  large  amount  of  heat  in- 
cident to  producing  power,  and  generates  more  heat 
for  process  purposes.  It  has,  however,  been  proven 
that  there  need  be  no  waste  of  heat  in  a  finishing  plant, 
other  than  the  unavoidable  losses  in  transmission;  and 
the  electric  motor  has  been  responsible  for  this  im- 
provement.    It  is  worth  while  to  reduce  a  fuel  bill  of 


$50000  to  $25000  through  an  ultimate  expenditure  of 
perhaps  $75  000 ;  and  that  this  is  possible  is  due  in  a 
large  measure  to  the  almost  ideal  characteristics  of 
the  adjustable-speed  motor  as  adapted  to  finishing  ma- 
chines which  must  be  driven  over  a  considerable  range 
of  speed. 

As  stated  before,  a  considerable  part  of  the  ma- 
chinery in  a  finishing  plant  must  be  driven  at  varying 
speeds.  Expressed  in  actual  horse-power,  this  may  be 
from  one-third  to  one-half  of  the  total,  depending  upon 
the  kind  of  finishing  that  is  done.  Until  the  advent  of 
the  adjustable-speed  motor,  these  varying-speed  ma- 
chines were  almost  universally  driven  by  small  en- 
gines, most  of  them  being  two-cylinder  inclined  en- 
gines with  cranks  set  90  degrees  apart,  cylinders  un- 
jacketed,  cutoflf  fixed  at  about  one-half  stroke  and  rat- 
ing from  5  to  30  horse-power,  according  to  the  ma- 
chines to  which  they  were  attached.  If  these  en- 
gines were  in  good  condition  they  would  develop  a 
horse-power  with  from  60  to  65  pounds  of  steam.  As 
actually  operated,  they  took  from  80  to  100  pounds  of 
steam  per  brake  horse-power. 

Fifteen  or  twenty  of  these  engines,  located  around 
the  plant  and  developing  one-half  or  less  of  the  actual 
horse-power  required,  would  take  more  steam  than  the 
main  prime  mover  which  drove  the  constant-speed  ma- 
chines through  the  usual  line  shaft  and  belts,  or  even 
through  electric-motor  drive  applied  to  constant-speed 
machines  only. 

There  are  three  types  of  these  engine-driven  vary- 
ing-speed machines,  viz. : — drying  cans  (using  a  com- 
paratively small  amount  of  power  but  a  large  amount 
of  low-pressure  steam  for  drying  purposes),  printing 
machines  (using  a  considerable  amount  of  power  and 
a  small  amount  of  low-pressure  steam  for  drying  pur- 
poses), and  tentering  machines  (using  a  moderate 
amount  of  power  but  no  steam  at  low  pressure  as 
usually  set  up). 

In  the  first  case,  the  exhaust  steam  from  the  en- 
gine is  used  in  the  drying  cans,  but  at  least  an  equiva- 
lent amount  must  be  taken  from  the  live  steam  mains, 
reduced  in  pressure  and  introduced  into  the  cans  to 
provide  the  heat  required.  In  the  second  case,  the 
amount  of  steam  exhausted  from  the  engines  is  greatly 
in  excess  of  that  which  can  be  used  in  the  machines. 
In  the  third  case,  all  of  the  exhaust  steam  must  either 
be  thrown  away,  or  diverted  to  machines  which  can 
use  it. 

The  solution  of  this  problem  might  appear  to  be 
to  run  a  low-pressure  main  around  the  plant,  exhaust- 
ing all  engines  into  it,  and  taking  all  low-pressure 
steam  from  it.     This  is  the  method  ordinarily  used  to 


November,  192 1 


THE  ELECTRIC  JOURNAL 


505 


conserve  heat,  but  the  final  result  is  that  the  balance 
between  departments  is  such  that  it  is  practically  im- 
possible to  make  the  supply  and  demand  equal.  In  al- 
most every  instance  the  amount  of  exhaust  available 
from  the  many  small  engines  was  more  than  sufficient 
to  supply  all  of  the  heat,  with  the  result  that  the  heat 
exhausted  from  the  main  unit  driving  constant-speed 
machines  was  entirely  wasted,  sometimes  to  a  con- 
denser and  sometimes  to  the  atmosphere. 

While  the  small  engine  might  appear  to  be  waste- 
ful of  heat,  it  would  ordinarily  be  given  credit  as  being 
a  very  flexible  and  easily  controlled  variable-speed  de- 
vice with  an  infinite  number  of  speed  changes  between 
maximum  and  minimum.  As  a  matter  of  fact  its 
speed  control  is  very  poor;  and  it  is  almost  impossible 
to  get  fine  graduations  of  speed  with  an  ordinary 
throttle  valve  operated  by  the  machine  tender.  The 
effect  is  somewhat  similar  to  that  of  an  electric  motor 
having  four  or  five  points  of  speed  control.  Further- 
more, if  an  engine  is  slowed  down  temporarily  and  an 
attempt  is  then  made  to  bring  it  back  to  its  previous 
speed,  there  is  little  assurance  that  the  speed  will  be 
the  same ;  and,  in  those  machines  in  which  the  speed 
should  be  limited  only  by  the  capacity  for  drying,  it  is 
seldom  that  the  highest  possible  rate  of  production  is 
obtained  with  the  engine  drive. 

Consider  now,  the  first  case  mentioned,  that  of  the 
set  of  drying  cans,  which  will  take  eight  horse-power 
to  drive  and  2000  pounds  of  steam  at  two  or  three 
pounds  pressure.  The  engine  will  exhaust,  say,  700 
pounds  of  steam  per  hour,  leaving  1300  pounds  to  be 
made  up  from  some  other  source.  If  this  1300  pounds 
of  steam  is  taken  from  the  live  steam  main  and  re- 
duced to  two  or  three  pounds  pressure,  no  mechanical 
work  has  been  obtained  from  it,  although  it  might  be 
made  to  produce  30  kilowatts  per  hour  of  energy  and 
still  deliver  90  percent  of  its  heat  to  the  drying  cans. 
This  30  kilowatts  of  energy,  however,  is  probably  be- 
ing turned  out  in  a  main  unit  utilizing  less  than  five 
percent  of  the  heat  delivered  to  it.  Take  the  engine 
from  these  cans  and  attach  an  eight  hp  adjustable- 
speed  motor.  This  motor  will  derive  its  power  from 
.■1  main  prime  mover  running  non-condensing  and  ex- 
hausting into  a  low-pressure  main  from  which  all  low- 
pressure  devices  can  take  their  steam.  To  drive  this 
eight  hp  motor  the  prime  mover  will  take  350  pounds 
of  steam  per  hour  as  against  700  for  the  small  engine. 
The  drying  cans  will  take  2000  pounds  of  steam  per 
hour  which  will  be  exhaust  steam  from  the  main  prime 
mover;  and  in  the  process  of  producing  that  low-pres- 
sure steam  the  prime  mover  will  deliver  to  the  line  45 
kilowatts  of  energy,  the  heat  in  one-quarter  of  which 
has  been  used  to  drive  the  drying  cans.  The  37  kilo- 
watts of  energy  produced  in  the  operation  of  supply- 
ing low-pressure  steam  to  the  drying  cans  becomes 
available  for  the  constant-speed  machinery,  and  has 
been  produced  at  practically  no  cost  other  than  the 
fixed  charges  upon  the  equipment. 


In  the  second  case,  that  of  the  printing  machines, 
the  maximum  power  required  will  be  30  hp,  but  the 
average  over  any  considerable  period  of  time  will 
probably  not  be  more  than  half  of  that,  or  say  15  hp. 
These  engines  will  have  large  cylinders  in  order  to 
provide  the  excessive  starting  torque  which  is  re- 
quired, with  the  result  that  the  water  rate  will  be  worse 
than  even  in  the  case  of  the  power  engine.  We  may 
take,  however,  as  an  average,  1200  pounds  of  steam 
per  hour;  but  only  half  of  this  will  be  required  in  the 
operation  of  the  printing  equipment,  leaving  600 
pounds  to  be  delivered  elsewhere.  It  is  by  no  means 
certain,  however,  that  this  additional  steam  can  be 
used  at  just  the  time  that  it  becomes  available. 
F'urthermore,  we  have  only  been  able  to  get  15  hp  out 
of  the  1200  pounds  of  steam  delivered  to  the  engine, 
whereas  we  might  have  obtained  27  to  28  kilowatts 
from  the  same  amount  of  steam  if  delivered  to  the 
right  kind  of  a  prime  mover,  or  sufficient  energy'  to 
drive  two  printing  machines. 

In  the  third  case  the  condition  is  simply  aggra- 
vated still  further,  inasmuch  as  the  engine  will  be 
called  upon  to  deliver  about  ten  horse-power,  and  will 
take  800  or  900  pounds  of  steam  per  hour  (which  may 
or  may  not  be  used  by  other  machines  according  to 
whether  it  is  needed).  The  real  trouble  is,  however, 
that  so  little  power  has  been  produced  in  the  opera- 
tion of  reducing  the  steam  from  boiler  pressure  to  low 
pressure,  making  it  necessarv'  to  generate  more  power 
In  a  large  unit. 

The  heat  balance  in  a  finishing  plant  is  such  that 
the  entire  mechanical  power  needed  can  be  produced 
in  the  process  of  reducing  steam  to  low  pressure, 
through  the  use  of  a  single  generating  unit  exhaust- 
ing at,  say  five  pounds  gauge  pressure  or  less. 

It  is  apparent  from  the  foregoing,  that  the  ad- 
justable-speed motor  has  made  possible  two  great  im- 
provements in  the  finishing  industry: — First,  the  sub- 
stitution of  one  main  generating  unit  providing  all  of 
the  power  required  for  the  entire  plant,  all  of  the  ex- 
haust steam  from  this  unit  being  used  in  the  processes, 
and  a  net  fuel  use  of  less  than  one-half  of  a  pound  of 
coal  per  kilowatt-hour;  and,  second,  any  range  of 
speed  that  may  be  required,  with  a  delicacy  and  sure- 
ness  of  control  that  cannot  possibly  be  obtained  with 
steam  engines. 

As  to  the  power  characteristics  of  the  varying- 
speed  machines,  there  is  much  that  may  yet  be  done 
in  the  way  of  careful  study  that  may  make  possible  the 
use  of  motors  especially  adapted  to  this  work.  Up  to 
the  present  time,  standard  adjustable-speed  motors 
have  been  used,  seldom  with  a  speed  range  of  more 
than  four  to  one,  often  with  a  speed  range  of  two  to 
one ;  but  perhaps  most  generally  with  a  three-to-one 
range.  Adjustable-speed  motors  are  usually  rated  on 
a  constant  horse-power  basis,  whereas  most  of  the 
varying-speed  finishing  machines  more  nearly  approach 
the  constant  torque  basis.     A  standard  10  horse-power. 


t;o6 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


adjustable- speed  motor  having  a  speed  range  of  from 
500  to  1500  r.p.m.,  will  usually  develop  10  horse-power 
at  any  speed  within  those  limits.  As  applied  to  a  set 
of  drying  cans  it  will  be  called  upon  to  deliver  10 
horse-power  at  1500  r.p.m.  and  the  horse-power  will 
decrease  with  the  speed,  not  exactly  in  proportion  but 
nearly  so.  At  500  revolutions-per-minute,  it  may  be 
called  upon  to  deliver  4  or  4.5  horse-power. 

At  the  higher  speed,  the  heating  of  the  field  is  a 
minimum,  and  the  cooling  effect  through  windage  a 
maximum.  On  the  other  hand,  the  armature  current 
is  the  maximum  at  the  highest  speed.  At  the  lowest 
speed  the  heating  of  the  field  is  a  maximum,  the  cool- 
ing effect  is  the  minimum,  but  the  armature  current  is 
also  at  a  minimum.  It  is  a  fact  that  in  most  cases  the 
standard  adjustable-speed  motor  will  run  hottest  at  tlie 
lowest  speed,  notwithstanding  the  comparatively  low 
horse-power. 

The  motor  may  be  called  upon  to  run  continuously 
at  the  highest  speed  for  perhaps  the  entire  day,  and  it 
should  have  a  continuous  rather  than  an  intermittent 
rating.  The  average  speed  over  a  considerable  period 
of  time  will  be  from  one-half  to  two-thirds  of  the 
maximum;  and  in  many  cases  the  maximum  will  only 
be  used  for  special  goods  and  for  a  brief  period  of 
time.  The  motor,  however,  must  be  capable  of  run- 
ning satisfactorily,  and  develop  the  maximum  horse- 
power at  maximum  speed,  if  for  only  one  day  in  the 
year. 

For  printing  machines,  the  characteristics  are 
somewhat  different.  The  load  is  constant  torque  for 
any  given  work,  i.e.  with  certain  patterns  in  the  print- 
ing machines  the  load  will  vary  nearly  with  the  speed ; 
hut  if  the  pattern  is  changed,  the  torque  for  any  given 
speed  may  be  very  much  more  or  less.  About  30 
horse-power  maximum  is  required  by  a  printing  ma- 
chine. For  patterns  which  involve  heavy  torque  the 
speed  may  be  high  for  many  hours,  requiring  the  motor 
to  develop  its  full  rated  load  at  maximum  speed. 

The  starting  torque  of  these  machines  is  also  high, 
and  may  require  150  percent  of  the  maximum  running 
current  for  the  initial  start.  This,  however,  is  for  but 
a  few  seconds.  There  are  a  great  many  classes  of 
work,  however,  in  which  the  maximum  speed  will  not 
require  over  12  to  15  horse-power,  and  in  which  the 
starting  torque  is  not  excessively  heavy.  It  is  prob- 
able that  a  printing  machine  motor,  averaged  over  an 
entire  year,  would  not  develop  15  horse-power;  but 
there  are  periods  of  time  when  it  will  run  for  many 
hours  at  its  maximum  rating. 

Motors  on  tentering  machines  have  very  nearly 
constant-torque  characterisitcs  for  about  all  classes  of 
work,  and  seldom  run  at  the  maximum  speed,  but  must 
do  so  when  required. 

Adjustable-speed  motors  lend  themselves  to  driv- 
ing ranges  of  machines  where  there  are  two,  three  or 
four  units  which  must  run  in  synchronism  or  prac- 
tically so,  but  controlled  as  one  unit.     The  writer  be- 


lieves that  he  made  the  first  installation  of  this  char- 
acter in  a  finishing  plant  some  twelve  years  ago,  in 
which  two  units  were  previously  coupled  mechanically 
through  long  shafts,  bevel  gears,  friction  cones,  etc., 
and  driven  by  one  variable-speed  motor  of  the  multiple- 
voltage  type.  The  shaft,  gears  and  cones  were  dis- 
mantled and  two  motors  used  on  one  controller,  with 
auxiliary  field  control  for  one  of  the  motors  to  take  up_ 
the  slack  between  the  two  units  of  the  range.  This 
worked  so  well  that  an  addition  was  made  in  the  form 
of  a  device  in  which  the  slack  between  the  two  units 
would  automatically  bring  about  a  slight  change  of 
speed  in  one  of  the  motors,  so  that  no  manual  labor 
was  required  to  maintain  the  exact  speed  between  the 
two  units  of  the  range.  This  has  now  become  almost 
standard  practice  in  finishing  plants  for  dye  ranges, 
tenter  frames  and  similar  machines. 

One  of  the  most  difficult  problems  to  solve  satis- 
factorily is  the  transmission  of  the  power  from  the 
motor  shaft  to  the  machine  shaft.  In  many  finishing 
machines  the  main  driving  shaft  runs  at  slow  speed,  in 
some  cases  as  low  as  60  r.p.m.  In  some  cases,  the  ma- 
chines to  be  driven  are  hot  and  it  is  undesirable  to 
locate  the  motor  close  to  them,  even  if  the  speed  char- 
acteristics permit.  Where  temperature  conditions  are 
favorable,  the  silent  chain  drive  is  satisfactory,  as  large 
speed  ratios  can  be  obtained  without  complication.  In 
a  few  cases  worm-gear  drives  have  proven  satisfac- 
tory; but  in  the  main  these  are  inefficient.  Rack- 
geared  motors  have  been  used,  but  these  are  again  more 
or  less  special. 

Motors  in  a  finishing  plant  are  subject  to  high 
temperature  and  an  excessive  amount  of  moisture.  It 
is,  therefore,  wise  to  standardize,  in  so  far  as  is 
possible,  both  as  regards  horse-power  ratings,  speed 
ratings  and  character  of  control,  and  be  able  to  re- 
place motors  quickly  with  spare  motors  on  hand.  This 
does  not  mean  a  burdensome  amount  of  spare  equip- 
ment, but  one,  two  or  three  spare  motors  may  save  a 
great  deal  of  lost  time.  It  is  not  necessary  that  all  of 
the  sizes  be  carried  on  hand,  as  a  large  motor  can  be 
temporarily  adapted  to  a  low  horse-power  machine,  if 
the  speed  is  right. 

As  to  control,  up  to  within  three  or  four  years,  the 
simple,  non-reversing,  machine-tool  type  of  drum  con- 
troller was  acceptable.  There  were  three  or  four 
points  of  armature  resistance  which  were  useful  m 
starting  machines  up  and  running  them  very  slowly  for 
cleaning  or  for  special  adjustment.  There  were  then 
from  fifteen  to  twenty  field  contacts  to  give  the  actual 
variation  in  speed  throughout  the  normal  range  of  the 
motor.  This  type  of  controller  must  still  be  con- 
sidered as  having  many  desirable  characteristics.  It  is 
simple  and  requires  little  attention  to  insure  continu- 
ous functioning.  Used  in  connection  with  an  under- 
voltage  and  over-load  relay,  the  motor  is  amply  pro- 
tected. 

The    push-button,    predetermined    speed    t\pe  con- 


November,  1921 


THE  ELECTRIC  JOURNAL 


507 


trollei"  has  gained  in  popularity,  due  largely  to  the  fact 
that  it  is  more  "fool  proof."  Controllers  in  a  finish- 
ing plant  are  subject  to  much  abuse,  and  if  the  opera- 
tor can  be  confined  to  manipulating  a  rugged  push- 
button, the  repairs  and  lost  time  are  reduced.  The 
push-button  predetermined  speed  type  controller  con- 
sists of  a  frame  with  slate  front  carrying  main  line 
contactor,  relays,  under-voltage  and  no-voltage  re- 
lease, armature  resistance  with  contactor,  etc.  The 
auxiliary  equipment  consists  of  a  push-button  device 
which  will  give  a 'Start,  stop,  slow  speed,  fast  speed, 
and  an  inching.  The  Slotv  speed  is  used  for  making 
the  adjustment  after  the  machine  is  started  and  is  ob- 
tained through  the  use  of  an  armature  resistance  which 
is  cut  out  of  circuit  when  the  Fast  button  is  pushed. 
The  Fast  button  gives  a  speed  dependent  upon  the 
setting  of  the  field  rheostat  which  is  mounted  nearby 
and  within  easy  reach  of  the  operator.  If  the  Stop 
button  is  pushed,  the  machine  will  stop  promptly 
through  the  dynamic  breaking  action  of  the  motor;  and 
if  the  Fast  button  is  then  again  pushed,  the  machine 
will  be  brought  up  to  the  same  speed  at  which  it  was 
running  before  it  was  stopped,  without  further 
manipulation  on  the  part  of  the  operator.  This  type 
of  controller  has  materially  reduced  the  number  of 
fuses  required,  as  both  the  starting  and  the  stopping 
current  are  held  within  a  definite  range  through  the 
action  of  the  controller  itself. 

Where  there  are  two  or  more  units  in  a  range, 
each  unit  driven  by  its  individual  motor  and  all  of  the 
motors  operated  from  one  controller,  the  field  rheo- 
stat may  have  capacity  for  all  of  the  motors;  but  in 
many  of  these  ranges  it  is  desirable  to  operate  one  of 
the  units  without  the  other,  and  in  such  cases  it  is  a 


better  arrangement  to  have  individual  field  rheostats 
for  each  motor,  but  coupled  on  one  operating  shaft.  It 
is  then  possible  to  operate  any  individual  unit  by  simply 
disconnecting  the  other  from  the  line. 

Up  to  the  present  time  there  is  no  satisfactory 
substitute  for  the  direct-current,  adjustable-.speed  mo- 
tor for  this  class  of  work.  Plant  owners  and  engi- 
neers would  certainly  welcome  an  adjustable-speed 
motor  that  would  operate  on  an  alternating-current 
circuit,  and  would  have  shunt  motor  characteristics. 
The  slip-ring  type  of  motor  does  not  have  enough  vari- 
ation in  torque  characteristics  to  give  good  speed  regu- 
lation. I'urthermore,  the  efficiency  and  power-factor 
are  not  satisfactory.  It  is  for  this  reason  that  many 
finishing  plants  have  adopted  the  direct-current  mo- 
tor for  the  entire  equipment,  whereas  the  alternating- 
current  motor  possesses  the  usual  desirable  character- 
istics for  the  constant-speed  machines. 

A  number  of  plants  are  using  alternating-current 
generating  equipment  and  alternating-current  motors 
for  constant-speed  drives,  operating  a  motor-generator 
set  to  provide  direct  current  for  the  varying-speed  ma- 
chines. This  is  a  very  desirable  arrangement  and,  by 
properly  proportioning  the  motor-generator  set,  con- 
siderable power-factor  correction  can  be  obtained. 

Plants  have  been  built  with  an  alternating-current 
generating  unit  and  a  direct-current  generating  unit, 
with  the  two  tied  together  electrically  through  a  motor- 
generator  set.  In  case  it  was  necessary  to  operate 
overtime,  either  unit  could  be  run  according  to  the 
preponderance  of  current  of  one  kind  or  another,  and 
the  motor-generator  set  used  to  deliver  either  alternat- 
ing or  direct  current  as  required.  This  arrangement 
possesses  no  great  advantage  over  the  single-unit  plant. 


CeiiXi'nl  ^Siadi^B  Povyor  for  TdxcH^  Mjlfe 


JOHN  H.  FOX, 

Engineer,  Mill  Power  Dept., 
Southern  Power  Company 


TEXTILE  manufacturers  have  had  to  go  through 
a  process  of  education  before  they  could  be 
brought  to  see  the  necessity  of  making  invest- 
ments in  electric  drive.  Their  mechanical  drives  were 
the  development  of  many  decades,  their  advantages 
and  disadvantages  were  known  by  experience. 

The  first  objection  they  raised  was  that  the  power 
source  was  placed  in  the  hands  of  others.  Consider- 
able argument  was  required  to  convince  operators  that 
the  central  stations  had  to  deliver  as  good  or  a  better 
service,  if  it  was  to  continue  its  existence;  and  that 
the  central  stations  had  made  tremendous  investments 
to  give  reliable  service. 

Then  again  electric  motors  were  unknown  factors, 
and  some  of  the  first  installations  of  electric  drive  were 
not  as  efficient  as  they  are  at  this  date.  The  feasibility 
of  the  claims  of  increased  production,  oiTered  bv  the 


central  station,  were  doubted.  Such  figures  and  state- 
ments as  were  given  were  looked  upon  with  distrust,  as 
being  biased.  "Doubting  Thomas"  had  nothing  on  the 
mill  man  who  had  used  mechanical  power  for  20  years 
or  less. 

Cost  of  operation  was  a  battle  fought  many  times, 
cost  i)er  horse-power  instead  of  cost  per  pound  of  pro- 
ducts was  the  banner  that  men  fought  under,  and 
pounds  per  spindle  product  was  only  discussed  in  the 
absence  of  the  practical  superintendent.  However, 
today  the  manufacturer  who  has  once  used  electric 
power  from  a  central  station  never  goes  back  to  the 
mechanical  drive. 

The  present  status  of  the  electric  textile  drive 
shows  that  there  are  today  approximately  12000000 
spindles,  in  the  United  States,  driven  by  the  power 
supplied  over  the  transmission  lines  of  the  central  sta- 


=;o8 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


tions.  Practically  29  percent  of  the  spindles  in  the 
United  States  depend  on  a  source  of  power  controlled 
by  companies  outside  of  the  mill  itself.  As  to  the  de- 
pendability of  service  rendered,  the  record  of  one  com- 
pany driving  four  and  three  quarter  (4%)  million 
spindles,  shows  an  average  of  operating  time  on  its  en- 
tire system  of  100  percent  delivery  of  time,  less  0.1683 
of  one  percent  for  24  hour  service  throughout  the  en- 
tire year. 

When  the  textile  manufacturer  realizes  that  the 
central  station  investment  is  one  of  large  magnitude, 
and  the  earning  capacity  of  which  varies  in  the  direct 
ratio  of  the  efficiency  of  its  service,  then  he  will  have 
no  lingering  doubts  on  the  question  of  dependability  of 
'the  central  station  service,  and  will  follow  the  experi- 
ence of  some  of  the  largest  textile  plants  in  the  United 
States. 

The  application  of  the  proper  type  of  electric  drive 
has  had  the  intensive  study  of  the  best  electrical,  me- 
chanical and  textile  engineers  of  the  country,  some  mis- 
applications have  been  made  during  the  past  due  to  the 
lack  of  textile  knowledge  by  the  electrical  engineers, 
or  the  lack  of  electrical  knowledge  by  the  textile  engi- 
neers.    However,  the   close   co-ordination   existing  be- 
tween these  engineers  today  has  made  the  highly  effi- 
cient and  practical  adaptation  of  the  electrical  and  me- 
chanical   knowledge    to    textiles    possible,    resulting    in 
greater  production  per  spindle  and  flexibility  of  opera- 
tion,   than   was    possible    with    the    mechanical    drive. 
Power  cost  per  pound  is  now  known,  not  only  in  the 
textile  plant  as  a  unit,  but,  in  each  department,  card- 
ing, spinning  or  weaving  is  calculated  or  measured  to 
an  accuracy  that  is  not  possible  with  mechanical  drive. 
There  is  no  more  economic  reason  why  the  textile 
plant  should  make  its  own  power,  than  that  it  should 
make  its  own  bobbins  or  shuttles.     The  primary  busi- 
ness of  a  textile  plant  is  manufacturing  cotton  goods. 
Incidentally,   it  is  a  manufacturer  of   as  many  other 
products  as  it  may  see  fit.     Some  plants  have  gone  so 
far  as  to  make  their  own  sizing  compounds,  but  few 
manufacturers  would  endorse  that  plan.     The  manu- 
facture of  power  by  textile  plants  has  been  conducted 
by  them  because  the  delivery  of  power  by  central  sta- 
tions is  a  comparatively  recent  development  compared 
with  the  textile  business,  and  had  not  reached  its  pres- 
ent stage  of  perfection  coincident  with  the  cotton  mill. 
The  writer  knows  only  too  well  the  many  fallacies 
of  deductional  reasoning  from  figures,  but  curves  of 
past  experiences  would  indicate  that  the  most  conserva- 
tive estimate  of  the  future  textile  growth   should  be 
placed   at   500000  spindles   yearly    for   the   next   five 
years.     Assuming  30  spindles  per  kw,  then  the  yearly 
increase    in   power    demand    would    be    16  600   kw    or 
50000000  kw-hrs.     There  is  a  great  probability  that 
two-thirds  of  this  power  will  be  required  by  the  states 
south  of  the  Mason  and  Dixon  line ;  fortunately  these 
states  have  a  larger  share  of  hydroelectric  possibilities 
than    the    northern    states.       While    in    the    past    the 
Atlantic  seaboard  has  had  more  of  this  class  of  indus- 


try, the  present  indications  are  that  there  is  a  strong 
tendency  to  locate  plants  near  the  cotton  fields  and  the 
less  expensive  hydroelectric  power.  At  present,  the 
writer  has  applications  from  textile  plants  for  over 
15  000  kw  that  are  unfilled,  and  unless  new  hydroelec- 
tric plants  are  developed,  those  plants  will  have  to  gen- 
erate their  own  power  (either  mechanical  or  electric) 
with  a  further  increase  of  coal  movements  added  to  an 
already  congested  traffic. 

Any  State  having  water  running  to  waste  in  its 
undeveloped  rivers  is  guilty  of  an  economic  crime,  it  is 
wasting  the  "white  coal"  and  burning  "black  coal". 
"Selling  its  birthright  for  a  mess  of  pottage"  is  a  weak 
simile  compared  to  the  State  which  does  not  cash  in 
on  its  possible  hydroelectric  power.  It  does  not 
"shop  at  home",  it  is  enriching  another  State  with  a 
purchase,  hinders  the  development  of  its  own  possibili- 
ties and  aids  in  depleting  the  country's  coal  resources. 
Experience  shows  that  (with  a  few  exceptions) 
the  textile  plant  built  near  the  site  of  a  small  water 
power  has  more  disadvantages  than  those  located  near  a 
town  or  a  city.  The  better  class  of  labor  has  objec- 
tions to  living  where  it  can  not  get  the  "benefits"  of  city 
life.  Usually  the  class  of  labor  content  to  live  "in  the 
sticks"  are  less  efficient,  than  those  enjoying  the  pleas- 
ures and  educational  advantages  secured  by  close 
proximity  to  cities.  Mills  built  at  or  near  compara- 
tively large  centers  of  population  manufacture  their 
own,  or  purchase,  power  without  any  seeming  handi- 
cap from  the  "free  power  site"  mill.  Power  is  only 
about  five  percent  of  the  manufacturing  cost,  and  many 
mill  men  have  declared  that  they  would  not  accept  such 
a  power  site  if  it  was  conditioned  on  building  a  plant 
thereon. 

As  between  purchased  power  or  manufactured 
power,  the  former,  if  generated  by  steam  plants,  has 
many  of  the  disadvantages  of  privately  manufactured 
power  during  coal  strikes,  railroad  congestion,  and 
fluctuating  prices;  while  the  hydroelectric  purchased 
power,  being  more  stabilized  as  to  price  and  quality,  is 
without  question  the  more  logical  answer  of  the  power 
problem.  Experience  shows  that  in  speed  regulation 
and  continuity  of  service  it  is  the  equal  of  the  large 
privately  owned  plant,  and  superior  to  the  privately 
owned  medium  or  small  plant.  The  same  is  also  true 
regarding  flexibility  of  operation  and  operating  cost. 

Each  State  should  encourage  the  formation  of 
companies  to  develop  its  natural  water  power  re- 
sources, and  also  see  that  its  laws  treat  such  companies 
in  such  a  manner  that  investments  are  secure  and  give 
?>  proper  return.  Due  to  the  greater  risks  in  hydro- 
electric developments  than  in  other  lines  of  business 
the  returns  should  be  greater  so  as  to  create^an  induce- 
ment to  increase  the  public  wealth  by  the  development 
of  the  natural  water  power  resources  of  the  State. 
There  are  something  like  50000000  undeveloped 
horse-power  in  the  rivers  of  the  United  States.  For 
vears  this  enormous  supply  of  power  has  been  running 
to  waste,  and  will  continue  to  run  to  waste  unless  the 


November,  1921 


THE  ELECTRIC  JOURNAL 


509 


public  policy  is  changed  toward  the  corporations  and 
the  investors  who  have  heretofore  taken  the  risk  of 
building  hydroelectric  properties. 

Public  Service  Commissions,  by  virtue  of  the 
powers  conveyed  to  them  by  legislatures,  have  taken 
away  the  right  of  barter  from  power  companies  and 
central  stations.  In  return  the  obligation  is  imposed  on 
them  to  see  that  the  utility  is  assured  a  fair  return  for 
its  investments.  Too  often  commissions  fix  rates  that 
will  not  allow  a  repeating  investment.  They  do  not 
allow  a  return  that  will  induce  capital  to  duplicate  their 
investments.  Certainly  such  a  return  should  be  given 
as  would  enable  water  power  bonds  to  compete  with 


State  and  municipal  bonds  that  "do  not  have  the  haz- 
ards of  water  power  developments.  If  the  Railroad 
Commmissions  or  Public  Service  Commissions  were 
also  charged  with  the  obligation  of  securing  the  capital 
and  men  necessary  to  develop  the  state  hydroelectric 
possibilities,  their  ideas  of  just  and  reasonable  return 
would  undergo  a  change.  The  problem  of  power 
supply  is,  and  should  be,  of  intense  interest  to  the  tex- 
tile manufacturer.  By  eliminating  an  investment  in  a 
power  plant,  he  can,  at  the  same  cost,  increase  the 
number  of  producing  spindles  by  at  least  15  percent, 
and  dividends  are  made  on  his  spindles  and  not  his 
power  plant. 


im 


'mM 


%) 


.f)t)ti 


1. 


*A 


(VlDtor^  niitl  Contra!  in 


Iiihhmg  PlajiU 


C.  VV.  BABCOCK 

Boston  District  Office, 
W'estinghouse  Electric  &  Mfg  Company 


FROM  the  viewpoint  of  the  plant  engineer  or 
master  mechanic  it  is  unfortunate  that  certain 
machines  in  almost  every  factory  require  adjust- 
able-speed operation  to  produce  the  work  expected 
from  thein.  Textile  mills  and,  in  particular,  textile 
finishing  plants  are  no  exception  to  the  rule,  and  ad- 
justable-speed drive  must  be  supplied  for  various  ma- 
chines— the  most  important  being  tenters,  starch 
mangles,  calenders,  dry  cans  and  printing  machines. 
The  best  possible  speed  control  should  be  used,  espe- 
cially on  print  machines,  for  the  quality  of  printed 
cloth  depends  largely  on  being  able  to  adjust  the  speed 
easily  to  the  pattern  being  printed. 

Both  alternating  and  direct-current  motors  have 
been  used  for  adjustable-speed  service  in  finishiiig 
plants  and  the  former  have  met  with  varying  degrees 
of  success.  However,  to  achieve  the  best  results,  from 
both  the  operating  and  the  production  point  of  view, 
direct-cufrent  motors  and  automatic  control  are  essen- 
tial. This  applies  to  printing  machines  in  particular. 
Though  textile  machines  in  general  requiring  variable 
speed,  are  of  the  constant-torque  type,  so  many  ele- 
ments enter  into  the  driving  of  printing  machines  that 
they  can  be  met  to  best  advantage  only  by  a  commutat- 
ing-pole,  adjustable-speed,  direct-current  motor  with 
push-button,  automatic  control.  Some  day,  an  alter- 
nating-current motor  may  be  produced  with  speed-tor- 
que characteristics  comparable  to  those  of  a  shunt  mo- 
tor, but  it  is  not  now  available.  On  the  other  Hand 
tenters,  mangles  and  calenders  can  be  acceptably  driven 
ty  slip-ring,  or  wound-rotor  motors,  for  in  these  cases 
close  adjustment  of  speed  is  not  needed. 

Another  consideration  enters  into  this  problem : — ■ 
the  quality  of  product  handled  by  the  mill.  Naturally, 
a  mill  finishing  the  cheaper  grades  of  cloth  or  printing 
only  in  few  colors,  does  not  require  the  same  degree 


of  refinement  in  driving  apparatus  as  mills  working  on 
better  grades,  and  in  these  cases  alternating-current 
can  be  used  for  variable  speed  work.  So  the  element 
of  first  cost  enters  into  the  discussion  and  is  to  be  bal- 
anced by  the  quality  of  the  output  of  the  mill. 

Power-factor  is  another  factor  which  is  becoming 
increasingly  important,  due  to  rapid  growth  in  the  use 
of  central  station  power.  This  can  be  taken  care  of 
by  means  of  a  synchronous  motor,  which  gives  a  logical 
solution  to  the  whole  situation.  By  the  use  of  a  syn- 
chronous-motor, direct-current  generator  set,  high 
power-factor  can  be  obtained  for  the  mill  as  well  as 
direct-current  for  the  adjustable-speed  machines. 
Therefore  it  is  easily  and  logically  possible  to  derive 
the  benefits  of  the  squirrel-cage  induction  motor  for 
the  constant-speed  machinery  and  direct-current  for 
the  adjustable  at  a  relatively  low  first  cost  for,  in  de- 
termining the  size  of  the  motor-generator  set  (direct- 
current  end  only),  load  factor  should  be  taken  into 
consideration.  In  a  recent  installation,  approximately 
530  hp  in  direct-current  motors  driving  printing  ma- 
chines and  tenters  are  run  by  a  200  kw  generator. 

This  applies  as  well  to  the  mill  with  its  own  prime 
movers,  for  better  power-factor  at  the  switchboard 
means  increased  capacity  of  the  main  generator  avail- 
able for  driving  squirrel-cage  induction  motors. 
Assume  a  1500  kv-a  generator  driving  alternating-cur- 
rent motors  and  a  200  kw  synchronous  motor-genera- 
tor set  for  adjustable-speed  motors.  With  a  plant 
power-factor  of  Jt,  percent,  the  generator  output  is 
1 100  kw,  and  if  this  is  raised  to  90  percent  the  output 
is  1350  kw.  Then,  taking  into  consideration  the 
losses  in  the  motor-generator  set,  about  30-kw,  there 
remains  a  surplus  of  about  220  kw. 

As  before  inentioned,  the  two  principal  types  of 
machines    requiring   adjustable-speed   are   the   printing 


THE   ELECTRIC  JOURXAL 


\o\.  XVIII,  No.  II 


machines  and  tenters,  and  these  should  be  considered 
separately.  Before  the  advantages  of  electricity  were 
available,  the  method  of  driving  the  former  was  by  an 
inclined  type  of  steam  engine  which  drove  directly 
each  machine  and  was  controlled  by  opening  or  closing 
the    throttle    valve.     Aside    from    being    cumbersome. 


FIG.   I — Pl'SH  BUTTON  CONTROL  ST.\TION  AND  SPEED  M.\STER  SWITCH 
MOUNTED   0."}    PRINTING    MACHINE 

very  poor  speed  regulation  was  obtained  and  all  the 
cMsadvantages  of  running  long  steam  supply  pipes  pre- 
vailed. 

In  applying  motors,  various  ways  can  be  used  to 
drive  the  main  shaft  of  the  machine,  depending  on  the 
space  available  or  whether  gears,  chains  or  belts  are 
desired.  The  controller  is  really  the  heart  of  a  suc- 
cessful printing  machine  and  should  cater  to  the  inher- 
ent features  found  in  its  construction.  The  printer 
should  be  able  to  give  his  undivided  attention  to  ad- 
justing the  rolls  and  seeing  that  they  register  properly, 
and  therefore  all  processes  of  starting,  stopping  and 
changing  speeds  should  be  done  with  as  little  effort  or 
attention  on  his  part  as  possible;  this  can  be  met  only 
by  a  full  automatic  contactor  controller,  with  the  push- 
button station  and  speed  control  master  switch  placed 
or  the  machine  itself.  The  inertia  and  starting  fric- 
tion of  one  of  these  machines  is  high  and  therefore 
suitable  means  must  be  provided  to  supply  enough 
voltage  to  the  motor  armature  to  cause  the  motor  to 
start  whenever  the  start  button  is  depressed.  This  is 
tiken  care  of  by  a  high-torque  relay  which  cuts  out 
part  of  the  resistance  for  a  few  seconds  only,  by  action 
of  the  motor  current.  Also  full  automatic  accelera- 
tion from  zero  to  any  speed  is  taken  care  of  by  flutter- 
ing-type  relays,  which  give  an  even  increase  in  speed, 
v.ithout  throwing  the  rolls  out  of  register  or  breaking 
the  cloth. 

Motors  with  a  speed  range,  by  field  control,  of  3 


ti^  I,  and  with  provision  for  three  armature  points  of 
control  have  been  found  to  give  the  most  satisfactory 
results.  The  armature  points  give  8,  16  and  24  percent 
approximately  and  the  field  points  from  33  to  100  per- 
cent of  maximum  speed,  in  about  30  steps.  Any  of 
these  speeds  are  obtained  from  the  speed  master 
switch ;  the  start  and  sJoiv  buttons  always  give  16  per- 
cent speed  regardless  of  the  setting  of  the  speed  master 
switch.  The  push-button  station  also  gives  an  inch  or 
jog  button  and  a  fast  button,  the  latter  bringing  the 
motor  up  to  a  speed  corresponding  to  the  setting  of  the 
speed  master  switch.  All  of  these  functions  are  ob- 
t.iined  from  a  three-button,  push-button  station  and 
speed  master  switch,  as  shown  in  Fig.  i.  The  push- 
button station  is  mounted  on  a  nip  of  the  machine,  with 
the  handle  of  the  speed  master  switch  brought,  by  a 
lemovable  extension,  within  six  inches  of  it,  so  that  the 
printer  has  full  control  of  his  machine  without  turning 
or  moving  from  his  position  in  front  of  it.  In  this 
case  the  motor  is  placed  on  the  mezzanine  floor  over- 
head, is  belted  to  the  main  shaft  and  the  controller  in  a 
dust  proof  cover  and  resistors  are  mounted  close  be- 
side it,  thus  saving  wiring  and  space.  Fig  2  shows  this 
equipment  and  Fig.  3  is  a  front  view  of  the  automatic 
control  panel. 


FIG.    2 — MOTOK   DRIVF    FOR    PRINTING    MALHl.St 

This    control    equipment    provides    these    essential 
e'ements : — 

Quick  and  easy  speed  adjustment. 

Long  lite  of  contacts. 

High  torque  for  starting. 

0\crload  protection  with  relay. 

Xo-voltage  protection. 

Dynamic  braking  for  quick  stopping. 

Fool  proof  operation. 

Operator's  entire  time  available  for  his  machine. 
It  is  really  remarkable  to  note  the  ease  with  which 
a  printer  can  control  one  of  these  large  machines  with 
this  control,  for  a  fifteen  color  print  machine,  with  its 


November,  1921 


THE   ELECTRIC  JOURXAL 


511 


numerous  dry  cans,  is  a  bulky  mechanism  and  covers 
much  floor  space,  and  both  quality  and  qtiantity  of 
production  are  bettered  by  this  type  of  drive. 

Tenters  offer  other  possibilities  for  the  profitable 
use  of  motors  and  automatic  control,  but  here  the  con- 
ditions are  slightly  different,  as  the  fine  adjustments 
tf  speed  are  not  so  important  and  only  one  amiature 
point  is  necessary  for  starting  the  material  through  the 
tenter.  Hence  alternating  or  direct-current  motors 
are  adaptable  though,  on  the  whole,  direct-current  is 
t(;  be  preferred.  As  the  cloth  is  usually  run  through 
a  starch  or  water  mangle  and  then  over  dry  cans  before 
entering  the  tenter,  these  three  machines  can  be  run 
by  one  motor  or  by  three  separate  ones.  Even  four  or 
five  can  be  operated  in  tandem  and  all  the  motors  con- 
trolled from  one  station,  and  this  method  of  control  is 
very  flexible  and  easily  operated.  Either  a  drum  or 
the  full  automatic  type  of  control  can  be  used,  but  the 
advantages  of  the  latter  are  evident  here  as  elsewhere. 


FIG.   3 — AUTOMATIC 


It  is  fool  proof,  requires  less  upkeep  cost  and  changes 
in  speed  are  more  easily  accomplished. 

In  running  two  or  more  motors  in  tandem,  some 
means  must  be  used  to  keep  the  relative  speeds  the 
same,  otherwise  the  cloth  will  either  be  broken  or  piled 
".p  between  the  machines.  To  accomplish  this,  a  dancer 
roll  is  connected  by  a  chain  over  pulleys  to  an  auxiliary 
field  rheostat.  This  dancer  roll  is  supported  by  the 
cloth  as.  it  comes  out  of  the  first  machine,  say  the 
mangle,  and  is  free  to  move  up  and  down.  It  is  evi- 
dent then  that  if  the  mangle  motor  runs  a  little  too 
fast,  the  dancer  roll  will  drop  and  this  then  cuts  out 
some  resistance  and  the  motor  slows  down  a  little  to  a 
point  where  equilibrium  obtains.  The  main  field  rheo- 
stats for  each  motor  are  either  coupled  together  and 
moved  by  one  handle  or  a  special  two  or  more  section 
rheostat  is  made  with  one  section  for  each  motor  and 
means  provided  for  varying  the  resistance  in  each  field 
circuit  together,  thus  changing  the  speed  of  all  motors 
together  as  desired.     The  dancer  roll  rheostat  for  each 


motor  is  in  series  with  the  main  rheostat.  One  less 
dancer  roll  equipment  than  the  number  of  motors  in 
tandem  is  all  that  is  necessary — thus  in  a  three-motor 
t-.ndem  outfit,  two  motors  only  need  be  kept  in  unison 
with  the  third. 

A  push-button  station  providing  Stop,  Start,  Inch, 
Slow,  Fast  with  an  automatic  controller  for  each  mo- 
tor and  a  safety  stop  station  completes  the  equipment. 
Automatic  acceleration  easily  and  gradually  starts  the 
motors  to  the  field  rheostat  setting  by  means  of  special 
fluttering  type  relays  and  the  dancer  rolls  then  keep  all 
motors  running  uniformly.  Fig.  4  shows  the  push- 
button station  with  the  main  field  rheostat  underneath 
at  the  delivery  end  of  a  tenter. 

As  it  is  sometimes  necessary  in  a  growing  mill  to 
relocate  machines,  it  is  better  to  keep  the  controller  for 
each  motor  in  a  separate  unit  and  it  can  then  easily  be 
moved  and  made  part  of  any  tandem  outfit  or  run 
separately  with  its  own  push  button  station.  This 
flexibility  is  not  possible  when  a  drum  controller  is 
used  with  one  set  of  starting  resistance  for  all  the  mo- 


FIG.    4 — PUSH    DLTTTON    CONTROL    STATION    WITH    SPEED    CONTROL 
RHEOSTAT   FOR   A   TENTER 

tors  in  a  tandem  unit.  Also  a  drum  controller  has  the 
disadvantage  that  long  runs  of  the  leads  from  each  mo- 
tor are  necessary,  instead  of  the  small  wires  required 
for  push  buttons. 

Generally  speaking,  the  decided  trend  in  the  tex- 
tile, as  in  other  industries,  is  to  the  use  of  automatic 
control,  embodying  as  it  does  so  admirably,  the  rolling 
type  of  contact,  which  outlasts  many  times  the  old  slid- 
ing contacts;  magnetic  blowouts  to  extinguish  the  arc; 
overload  and  no-voltage  protection  features  and,  not 
the  least  by  any  means,  the  ability  to  stand  up  under 
the  hardest  kind  of  service  without  any  chance  of  an 
inexperienced  operator  damaging  any  part  of  the 
equipment,  in  other  words  it  is  practically  fool  proof. 

Rapid  strides  have  been  made  in  recent  years  in 
the  development  of  electrical  apparatus  to  meet  the 
exacting  needs  of  finishing  plants,  but  it  is  not  easy  to 
conceive  of  new  improvements,  which  will  replace  the 
commutating-pole,  adjustable-speed,  direct-current  mo- 
tor with  push-button  automatic  control,  for  those  ma- 
chines requiring  speed  adjustment. 


an^  Electric  Drive 


C.  T.  GUILFORD 

General  Engineer, 
W'cstinghouse  Electric  &  Mlg.  Company 


RA\\'  silk  is  the  product  of  tiie  silk  worm,  which 
at  the  close  of  its  life  of  about  two  months,  spins 
itself  up  into  a  cocoon,  the  layers  of  which  con- 
stitute a  filament  measuring  from  0.0003  to  0.0008 
inches  in  diameter  and  from  300  to  8000  yards  in  length 
and  requiring  about  1000  miles  to  make  up  one  pound 
of  silk.  The  first  step  necessary  to  get  the  silk  into 
workable  size  is  to  soften  these  cocoons  in  hot  water 
to  make  the  filaments  unravel  readily,  and  also  to 
soften  the  gum  or  silk  glue,  called  sericin.  Five  or 
more  of  these  cocoon  filaments  are  brought  together 
and  caused  to  twine  around  each 
other  while  the  sericin  is  soft  and 
sticky  when  they  become  agglutin- 
ated into  one  compact  thread  and 
reeled  up  into  skeins  of  from  40000 
to  50000  yards.  A  five  cocoon  silk 
has  about  300000  yards  to  a  poun  1 
and  measures  about  0.0022  inche- 
in  diameter.  The  breaking  strengili 
of  a  five  cocoon  thread  is  about  < « 1 
grams,  the  elasticity  from  15  to  jn 
percent  depending  largely  up"" 
humid  air  conditions.  About  _''  > 
percent  of  the  thread  is  sericin  oi 
silk  glue  and  80  percent  real  fibre 
The  sericin  becomes  hard  and  bri; 
tie  under  a  dry  atmosphere  and  to 
get  good  spinning  results  the  thread 
must  be  rendered  pliable  either  h\ 
a  moist  atmosphere  or  treating  witli 
an  emulsion  of  soap  and  oil. 

Reeling  is  done  largely  where 
the  silk  is  raised,  as  in  China  an'l 
Japan,  and  the  silk  is  shipped  in  the 
form  of    skeins   packed   in   bales,    in  p,;-.  ^. 

which    form   it  is   received  by    the 
throwing    mills     in    this     and    other  *■"'•  "*""' 

countries  where  the  silk  is  made  in-to  manufactured 
articles. 

THROWING   OR   SPIXNIXG 

The  process  of  silk  throwing  or  spinning  is  twist- 
ing, doubling  and  re-twisting  the  silk  from  the  skein 
into  yarn  of  the  desired  size  and  strength  for  use  in 
the  manufacturing  processes,  such  as  knitting  and 
weaving.  The  process  is  analogous  to  cotton  twisting 
although  the  machines  used  are  called  spinners. 

The  first  step,  called  winding,  is  to  transfer  the 
silk  from  the  skeins  on  to  spools  for  the  spinners, 
'the  different  operations  of  throwing  are  called  wind- 
ing, first  time  spinning,  second  time  spinning,  doubling, 


twisting  and  reeling.  Each  may  be  performed  on 
separate  machines,  although  in  some  cases  two  or  three 
processes  are  combined  and  accomplished  on  the 
same  machine.  In  the  first  time  spinning,  the  single 
thread  is  placed  on  the  spinning  spindle  and  given  a 
certain  amount  of  twist.  In  the  second  time  spinning 
two  or  more  of  these  threads  are  twisted  together  mak- 
ing a  thread  proportionately  larger.  Doubling  is  the 
process  of  bringing  two  or  more  threads  together  as 
one  thread;  on  the  5-B  combination  spinner  and 
doubler  it  is  given  from  2  to  3.5  turns  per  inch.  When 


^IN'i.ll       I'l 


KIG.    .; — DOUBLE    DECK    SILK    SI'INNER 
-COMBINATION    SPINNING,  DOUBLING  AND  TWISTING   MA- 
CHINE   FOR    SILK 
OMBINATION    DOUBLING  AND   SPINNING    MACHINE   FDR   SILK 

more  twists  are   wanted  this   is  added  on   the  second 
time  spinner. 

THE   SPINNER 

The  essential  parts  of  the  spinner  are  shown  in 
Fig.  I.  ^  are  the  vertical  steel  spindles  which  carry 
the  bobbins  B  containing  the  silk  to  be  spun.  C  are 
the  take-up  rolls  which  take  the  spun  silk  and  feed  it 
tj  the  receiving  spool  D  upon  which  it  is  wound.  The 
spindles  are  driven  by  a  belt  E  which  runs  -in  contact 
v.ith  the  whirl  F  of  the  spindle.  The  spindle  belt  E  is 
driven  by  the  pulley  G  on  the  vertical  shaft  H  which  in 
turn  is  driven  by  a  belt  from  a  line  shaft  over-head 
through  the  idle  pulleys  /  and  the  driven  pulley  /  on 


November,  1921 


THE   ELECTRIC  JOURNAL 


513 


the  vertical  shaft.  The  speed  of  the  spindles  ranges 
from  6000  to  14000  r.p.m.,  depending  upon  the  class 
of  spinning  to  be  done  and  the  style  of  machine  used. 
Four  styles  of  spinners  are  in  general  use  accord- 
ing to  the  number  of  operations  to  be  performed. 

1 — A  single-deck  spinner  is  shown  in  Fig.  I.  The  term 
single  deck  refers  to  a  set  (two  rows)  of  spindles,  one  on 


its  belt  drive  to  the  machine  and  drive  each  spinner  by 
■c  single  motor.  Various  forms  of  drive  have  been 
tried.  One  of  the  first  was  that  of  a  horizontal  motor 
placed  on  the  floor  or  on  a  bracket  and  driving  with 
bevel    gears   to   the   vertical    shaft   of   the    spinner,   as 


FIO.    5 — OLD   METHOD   OF  DRIVING   SILK   SPINNERS   WITH    HORIZONTAL 
MOTOR    AND    BEVEL   GEARS 

each  side  of  the  machine,  located  in  the  same  horizontal 
plane.  This  style  of  spinner  may  be  used  for  either  first  or 
second  time  spinning. 

2 — A  double-deck  spinner  is  shown  in  Fig.  2.  "Double- 
deck"  refers  to  two  double  rows  of  spindles,  the  one  located 
directly  above  the  other.  This  machine  may  be  used  for 
either  first  time,  second  time  or  both  first  and  second  time 
spinning.  In  the  latter  case  the  first  and  second  time  spin- 
ning is  one  continuous  process. 

3 — A  combination  spinning,  doubling  and  twisting  frame 
is  shown  in  Fig.  3.  This  is  also  a  double-deck  machine  with 
two  rows  of  spindles  on  each  side  of  the  lower  deck  and 
one  row  on  each  side  of  the  upper  deck.  The  silk  spun  on 
each  two  of  the  spindles  on  one  side  of  the  machine  passes 
through  a  common  guide  eye  to  the  feed  rolls  at  the  top  of 
the  machine,  from  which  it  is  fed  to  a  single  spindle  on  the 
side  of  the  machine  on  the  upper  deck.  This  spindle  gives 
the  final  twist  to  the  two  strands,  thus  making  the  completed 
yarn  and  winding  it  on  to  the  bobbin  on  this  spindle. 

4 — Combined  doubling  and  spinning  for  tram  is  shown 
in  Fig.  4.  This  is  also  a  single-deck  spinner.  Two  threads 
are  taken  from  the  spools  at  the  top  of  the  machine  and 
pass  through  the  rolls  at  the  center  of  the  machine,  where 


nc.   7 — STANDARD  VERTICAL    I760  R.    P.    M.    MOTOR  DRIVING   A    SINGLE 
DECK    SPINNER 

The  spindle  belt  is  driven  direct  from  the  motor  pulley. 

the  threads  are  doubled,  then  taken  to  the  spindle  on  the 
lower  deck  where  the  thread  is  spun  or  given  the  proper 
amount  of  twist. 

ELECTRIC   DRIVE 

The  original  method  of  drive  for  these  machines 
v.-as  by  belt  from  the  mill  line  shafting. 

The  next  step  was  to  eliminate  the  line  shaft  with 


FIG.   6 — COMBINATION   SPINNING,  DOUBLING   AND  TWISTING   MA- 
CHINE  DRIVEN    BY    A    HORIZONTAL    MOTOR 

shown  in  Fig.  5.  The  disadvantages  of  this  form  of 
drive  were  noise,  inefficiency  and  the  excessive  wear 
of  the  bevel  gears. 

Another  form  was  to  place  the  motor  on  the  floor 
and  connect  it  by  a  belt  or  chain  direct  to  the  cross  head 
shaft  of  the  machine,  as  shown  in  Fig.  6.  The  disad- 
vantage of  this  form  is  that  it  takes  up  valuable  floor 
space,  and  retains  the  crosshead  drive  with  its  quarter- 
turn  spindle  belt. 

Single  and  Double-Deck  Spinners — A  new  and 
efiiective  method  of  drive  applied  to  either  a  single-deck 
or  double-deck  spinner  is  that  of  a  vertical 
motor  having  a  shaft  extension  and  pulley  at 
the  top  for  the  single-deck  spinner  and  a  shaft  ex- 
tension at  both  top  and  bottom  with  pulleys 
for     the     double-deck     spinner     and     driving     direct 


FIG.  8 — TWO  DOUBLE  DECK   SILK  SPINNERS  DRI\-EN  BY  A   I/fo  R.  P.   M. 
VERTICAL    MOTOR 

on  to  the  spindle  belts.  Fig.  7  shows  this  method,  us- 
ing a  standard  vertical  motor  mounted  on  the  floor  and 
driving  a  single-deck  spinner.  Belt  tension  for  the 
spindle  belt  is  taken  care  of  by  weight  and  rack  at  the 
opposite  end,  being  part  of  the  machine  furnished  by 
the  machinery  builder.  This  form  represents  by  far 
the  simplest  and  easiest  method  of  driving  these  ma- 


514 


THE   ELECTRIC  JOURXAL 


Vol.  XN'III,  No.  II 


chines.  It  eliminates  the  vertical  belt  drive  from  the 
line  shaft  down  to  the  machine  together  with  the 
brackets  and  idlers  for  this  belt  and  the  driven  pulleys 
en  the  vertical  shaft.  The  motor  takes  up  about  the 
same  space  as  the  brackets  and  idlers  at  this  end  of 


FIG.    9 — STAND.\RD   VERTICAL  ^S70   R.    P.    M.    MOTOR    DRIVING    A    SIXGLE 
DECK    SILK   SPINNER 

the  machine,  hence  no  additional  floor  space  is  re- 
quired, nor  are  any  changes  necessarj'  on  the  spinner. 
Two  single-deck  spinners  can  be  driven  by  the 
same  type  of  motor,  mounted  between  them.  The 
spindle  belts  are  driven  from  a  double  flanged  pulley 
at  the  top  of  the  motor,  one  spinner  being  raised  two 
inches  above  the  level  of  the  other  to  accommodate  this 
drive.  This  method  has  the  advantage  of  saving  a 
total  of  about  three  feet  of  floor  space  at  the  ends  of 
I  he  machine.     A  similar  drive  is  used  with  the  narrow 


Fig.  8  shows  a  standard  vertical  motor  driving  two 
double-deck  spinners.  The  motor  has  a  shaft  exten- 
sion on  both  top  and  bottom  ends  and  drives  direct 
onto  the  spindle  belts.  This  same  form  of  drive  may 
be  applied  to  one  spinner.  One  frame  is  raised  two 
inches  above  the  level  of  the  other  in  order  to  accom- 
modate the  double  flanged  pulleys  on  the  motor.  This 
chive  has  the  advantage  of  saving  considerable  floou 
space. 

Direct  Connected  Motor — The  latest  and  most 
(.ornpact  form  of  drive  for  the  wide  single  and  double- 
r'eck  machines  is  that  of  a  motor  mounted  central  with 
the  vertical  shaft  of  the  spinner  and  coupled  to  it,  as 
shown  in  Fig.  9.  The  lower  bracket  of  the  motor 
serves  as  the  mounting  base  for  the  end  stand  of  the 

I    ;y  Spindle 


KIG.     10 — STANDARD 


HORIZONTAL    MOTOR    DRIVING 
DOUELER    AND    SPINNER 


A    COMBINATION 


type  of  spinner,  two  idler  pulleys  being  placed  on  the 
outside  of  the  end  stand,  one  on  each  side  of  the  spindle 
belt,  to  give  this  belt  wrap  enough  to  drive  the  take-up 
pulley. 


FIG.     II— STANDARD    VERTICAL    MOTOR    DRIVING    A    COMBINATION 
DOUBLER    AND    SPINNER 

Spinner,  and  the  vertical  shaft  which  drives  the  take-up 
gears  is  inserted  in  the  hub  of  the  spindle  belt  pulley, 
which  serves  as  a  coupling,  thus  assuring  perfect  align- 
ment with  the  motor  shaft.  The  motor  is  self  con- 
tained with  the  machine,  and  as  the  motor  rests  on  its 
broad  base  mounted  on  the  floor  the  whole  gives  a  very 
rigid  support.  To  install  this  motor  it  is  only  neces- 
sary to  cut  out  the  cross  web  at  the  lower  part  of  the 
end  stand  to  admit  the  motor,  insert  the  studs  on  the 
feet  of  the  end  stand  into  the  motor  bracket,  and  cut 
oflr"  the  vertical  shaft  to  the  proper  length  to  fit  into  the 
spindle  belt  pulley.  Brackets,  idlers  and  driven  pulleys 
provided  for  belt  drive  may  be  removed. 

In  the  case  of  new  machines  the  end  stand  of  the 
frame  may  be  furnished  with  the  lower  web  omitted, 
also  omitting  the  brackets  and  idlers  and  driven  pulleys 
required  for  belt  drive.  This  form  of  drive  is  com- 
pact and  stable,  requiring  practically  no  changes  on  the 


November,  .1921 


THE   ELECTRIC  JOURXAL 


machine.  The  motor  and  base  do  not  extend  beyond 
the  guard  of  the  spindle  belt  pulley,  the  drive  takes  up 
less  floor  space  then  any  other  yet  designed,  and  no 
iidditional  safety  guards  are  required  for  the  motor. 

Combined  Doubler  and  Spinner  for  Tram — Two 
methods  of  drive  are  used  for  this  spinner.  In  one 
method  a  motor  is  bolted  to  the  end  stand  of  the  frame 
just  above  the  cross  head,  connected  by  chain  to  a 
sprocket  on  the  overhung  shaft  of  the  cross  head,  as 
shown  in  Fig.  10.  Wire  screen  guards  are  placed  over 
the  motor  and  cross  head,  thus  insuring  complete  safet}' 


for  operators.  In  the  other  method  a  standard  vertical 
motor  is  placed  on  the  floor  or  on  a  bracket  immediately 
outside  of  the  end  stand  of  the  frame,  driving  the  spin- 
dle belt  direct  from  a  shaft  extension  and  pulley 
at  the  top  of  the  motor,  as  shown  in  Fig.  11.  The  feed 
is  driven  by  a  vertical  shaft  coupled  to  the  motor  shaft 
through  bevel  gears  at  the  top.  This  method  gives  a 
compact  and  simple  drive,  eliminating  the  cross  head 
with  its  pulleys,  brackets,  quarter  turn  belt,  as  well  as 
the  pulleys,  belts,  and  bevel  gears  required  to  drive  the 
feed. 


Day  UH^I  i^llj^ivi:  Llslrikg  in  Td:xc1Io  M!I1^ 


SAMUEL  G. 

Ilhiminatiiig 
The  W'estinghou 

SELDOM  does  the  person  in  charge  of  the  light- 
ing of  a  textile  mill  have  sufficient  facilities  to 
know  what  it  is  that  he  is  buying.  He  pur- 
chases "lighting  fixtures" — lamps,  reflectors,  hangers, 
and  his  investment  in  such  equipment  is  far  too  fre- 
quently gaged  solely  by  the  first  cost  of  that  equip- 
ment, or  by  the  cost  of  the  electrical  power  to  operate 
the  lamps.  Perhaps  he  assists  in  the  design  of  a  new 
mill  building  and  in  the  placing  of  the  machines ; 
but  for  the  daylight  illumination  overlooks  the  fact 
that  to  secure  usable  daylight  he  must  expend  thought 
and  seek  experience,  for  windows  can  seriously  hinder 
as  well  as  aid  production  and  vision.  Moreover,  it 
frequently  costs  as  much  to  operate  the  glazed  areas 
as  it  does  to  operate  incandescent  lamps ! 

In  the  first  place,  in  mill  lighting,  we  should  seek 
to  buy  a  result  and  not  an  article  of  equipment.  We 
should  purchase  and  evaluate  actual  resultant  illumina- 
tion, and  not  merely  glassware  and  metal.  We  must 
know  and  buy  useful  illumination,  and  we  tnust  base 
our  operating  cost  of  lighting  upon  "dollars  per  foot- 
candle  or  lumen" — not  upon  "dollars  per  outlet  or  per 
fixture."  For  example,  a  purchaser  of  coal  for  a  large 
industrial  establishment  does  not  buy  merely  so  many 
tons  of  a  black  substance,  and  be  satisfied  if  the  coal 
is  merely  black  in  color,  and  of  certain  sized  lumps 
He  purchases  coal  of  a  specified  heating  value,  and 
which  has  a  specified  percentage  of  ash  and  definite 
clinkering  qualities, — i.  e.,  he  really  purchases  a  usable 
heating  or  steam  making  ability.  And  so  it  should  be 
with  illumination,  either  natural  or  artificial.  It  is 
ability  to  see,  and  illumination  on  the  work,  that 
should  be  the  first  consideration,  and  the  only  measure 
of  true  efficiency  in  lighting  a  mill  is  "how  much  per 
unit  of  useful  light,"  not  what  is  the  price  of  the  lamps, 
glassware  and  accessories. 

Every  textile  mill  operator  would  like  to  know 
whether  his  lighting-  system  is  more,  or  less,  efficient 
than  that  of  his  neighbor.  To  obtain  any  knowledge 
of  lighting  economics,  one  must  have  a  common  meas- 


HIBBEN 

Engineer, 
se  Companies 

ure  of  the  light,  and  this  would  be  simple  if  it  were 
as  easy  for  a  mill  manager  to  think  in  terms  of  lumens 
of  light  as  it  is  to  think  of  quarts  of  water,  pounds  of 
steam,  or  yards  of  silk.  Yet  there  is  nothing  complex 
about  knowing  or  measuring  this  item  called  illumina- 
tion. Suppose  we  substitute — in  imagination — a 
cloudy  sky  for  the  ceiling  of  the  factory,  and  also 
imagine  a  fall  of  snow  from  that  cloud.  If  the  snow 
accumulates  on  the  floor  to  a  certain  thickness,  we 
place  a  yard-stick  vertically  into  it,  and  by  measuring, 
we  might  say  it  is  one  foot  thick.     Now  if  light  v<'erz 


FIG.    I — A  POOR  LIGHTING  INSTALLATION  IN  A  SPINNING  ROOM 

The  bare  lamps  on  drop  cords  suspended  close  to  the  opera- 
tors' eyes  produce  a  glare  and  cause  harmful  effects  to  the  eye 
sight. 

allowed  to  fall  upon  the  floor  from  overhead  lamps, 
we  could  similarly  measure  the  thickness  of  "light- 
fall"  by  using  not  a  yard-stick  this  time,  but  a  foot- 
candle  meter  and,  whereas  the  thickness  of  snow-fall 
might  be  a  certain  number  of  feet,  the  thickness  of 
light-fall  (or  the  value  of  horizontal  illumination) 
would  be  a  certain  number  of  foot-candles. 

Carrying  out  the  same  analogy,  in  order  to  evalu- 
ate the  quantity  of  snow  on  the  floor,  we  naturally 
would  measure  the  area  covered,  and  multiply  that 
area  by  the  thickness  of  snow,  thereby  ascertaining  the 


^i6 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


cubic  feet  of  snow.  To  know  the  quantity  of  useful 
illumination  we  multiply  in  exactly  the  same  manner, 
the  area  illuminated  by  the  foot-candles  of  illumina- 
tion falling  upon  that  area  or  surface,  and  get  a  new 
unit  which  cannot  be  called  quarts,  cubic  feet,  or 
bushels  of  light,  but  which  we  call  "lumens"  of  light. 

It  is  not  difficult  to  get  a  true  measure  of  lighting 
costs,  by  evaluating  it  in  cents  per  lumen,  just  as  we 
would  evaluate  wheat  in  dollars  per  bushel.  Keep- 
ing in  mind  this  fundamental  conception  of  illumina- 
tion, we  can  note  profitably  some  of  the  cardinal  points 
governing  textile  mill  lighting,  summed  up  as  follows : 

I — The  laws  that  are  in  force  to  protect  workmen 
against  inability  to  see  and  to  afford  them  self-pro- 
tection, require  not  less  than  two  foot-candles  of  il- 
lumination for  moderate  or  average  work,  and  not  les^ 
than  three  foot-candles  for  close  discrimination  of  de 
tail.  These  are  minimum  values,  and  it  is  usually  pro 
fitable  to  exceed  them  materially. 

2 — Bare  lamps,  especially  of  the  gas  filled  or 
Mazda  C  types,  when  hung  low,  as  on  drop  cords,  or 
placed  in  the  field  of  vision,  are  prima  facie  evidence 


25  percent  by  an  application  of  white  paint  to  the  ceil- 
ing. Paying  good  money  for  the  generation  of  light, 
and  then  allowing  it  to  be  absorbed  by  dark,  smoky 
walls  and  ceilings  seems  as  illogical  as  to  build  water 


FIG.    2 — MODERN   GENERAL   LIGHTING    OF    A    COTTON    MILL 

of  reckless  waste  of  light  and  of  detrimental  glare. 
Such  a  spinning  room  as  shown  in  Fig.  i  is  poorly 
lighted,  and  the  contrast  between  it  and  Figs.  2  or  3 
demonstrates  conclusively  the  superiority  of  an  instal- 
lation using  shaded  overhead  lighting  units. 

J— The  shallow  dome  or  flat  metal  reflectors  are 
obsolete  as  far  as  their  proper  use  for  general  over- 
head lighting  is  concerned,  and  the  most  modern  and 
efficient  reflectors  for  use  with  bowl-enameled  Mazd.i 
C  lamps  are  of  the  RLM  shape,  the  angle  type,  or  tlie 
deep  bowl  shape.  There  is  no  gain  in  using  the  deep 
bowl  metal  reflectors  in  place  of  the  RLM,  except 
where  it  is  desirable  to  shade  the  lamp  filament  more 
completely  from  direct  view. 

4 — Elimination  of  glare  is  more  than  a  matter  of 
comfort,  it  is  a  distinst  move  towards  economy.  Any 
photographer  who  points  a  camera  towards  the  sun 
in  taking  a  picture,  would  expect  a  fogged  plate;  any 
workman  facing  a  bare  lamp  will  get  blurred  images 
of  the  machinery  or  textiles  that  he  is  straining  to  see. 

5 — Light  colored  interiors  are  valuable  aids  to 
lighting.     One   typical   mill   increased   the   illumination 


L.  - 


FIG.    3 — I'KOIT.R    II.I.rMlNAIIoX    AII.uWn    I  ACH    THREAD   TO    i.        i:     ' 

reservoirs  of  sand  and  allow  the  water  to  soak  away 
into  the  earth. 

6 — The  frequent  cleaning  of  textile  mill  lighting 
equipment  is  especially  necessary,  because  lint,  dust 
and  oil  vapors  accumulate  upon  lamp  bulbs  and  re- 
flector surfaces  to  such  an  extent  that  the  efficiency 
of  the  system  falls  to  75  percent  or  less  of  its  initial 
output,  after  two  or  three  weeks  of  neglect.  When 
washing  lighting  equipment,  it  is  important  to  remove 
all  soapy  solutions  or  films,  lest  dust  adhere  to  such 
invisible  films.  One  should  dry  reflectors  carefully, 
preferably  with  tissue  paper.  It  is  a  good  plan  to  have 
a  lamp  rack,  similar  to  that  shown  in  Fig.  4,  in  the 
stock  room,  so  that  the  maintenance  man  can  there- 
with more  easily  take  out  new,  and  bring  back  old 
lamps. 

7 — Do  not  forget  that  Mazda  lamps  must  be 
burned  at  their  rated  voltage  in  order  to  produce  light 
most  economically.  The  candle-power  of  a  lamp  falls 
off  rapidly  as  the  operating  voltage  is  reduced.  Lamps 
rated  at  no  volts  and  burned  on  circuits  that  actually 


FIG.   4— A  LAMP  CARRYING  RACK  FOR  CLEANING  AND   MAINTENANCE 

measure  105  volts  at  the  sockets,  are  producing  only 
8s  percent  of  their  rated  amount  of  light. 

8 — Lighting  units  for  general  overhead  or  broad- 
cast illumination  should  be  connected  in  rows  parallel 


November,  1921 


THE  ELECTRIC  JOURNAL 


517 


to  the  windows,  so  that  the  faiHng  dayHght,  evidenced 
by  darkness  occurring  first  down  the  center  of  the  room 
may  be  supplemented  by  artificial  light  only  where 
needed. 

p — Natural  daylight  falls  in  value  very  rapidly  as 
one  moves  away  from  the  windows.     Fig.  5  illustrates 


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FIG. 


-CHANGES    IN    DAYLIGHT   ILLUMINATION    WITHIN    A    FACTORY 
THROUGHOUT  A  JUNE  DAY 

The  building  extends  north  and  south,  has  a  16  ft.  white 
ceiling  and  the  walls  are  60  percent  clear  glass. 

this  fact,  and  shows  as  well  that  the  natural  daylight 
within  a  room  changes  greatly  from  hour  to  hour. 
The  east  side  of  a  mill  needs  artificial  light  to  supple- 
ment daylight  in  the  late  afternoon;  the  west  side  needs 
artificial  light  in  the  morning. 

10 — The  color  of  daylight  changes  from  hour  to 
hour.  Fig.  6  shows  that  afternoon  sunlight  is  relative- 
ly low  in  its  percentage  of  violets,  blues,  and  greens, 
but  high  in  reds  as  compared  to  north  skylight.  Tex- 
tile work  that  involves  color  matching  is  influenced  by 
this  fact,  and  hence  daylight  cannot  be  depended  upon 
as  a  color  standard. 

Taking  up  the  most  important  parts  of  a  textile 
mill,  place  by  place,  it  is  well  to  note  the  results  of  a 
number  of  operators'  experiences  as  follows: — 

Cotton  Carding  and  Drawing — Detailed  vision  is 
not  essential,  and  broadcast  general  illumination  is  suf- 


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Blue  Green         Yellow     Orange     Red 

Wave-Length  i 


FIG.  6 — CHANGEABLE  COLOR   QUALITY  OF  DAYLIGHT 

hcient.  Small  individual  drop  lights  are  being  discon- 
tinued, and  modern  mills  are  now  using  1.5  to  3.0 
foot-candles,  from  metal  dome  reflectors  hung  at  about 
10  feet,  spaced  on  20  to  25  foot  centers,  and  equipped 
with  150  watt  lamps. 


Spinning  Frames,  Twisters,  Spoolers —  More  il- 
lumination is  required,  as  the  threads  become  succes- 
sively smaller.  Up  to  the  finer  work  it  is  well  to  in- 
crease the  illumination  to  5  to  8  foot-candles,  meaning 
about  1.5  watts  per  square  foot  of  floor  area. 

Warpers — Fig.  3  shows  a  system  to  take  care  of 
this  class  of  work.  Individual  threads  must  be  visible, 
which  means  an  installati(jn  of  at  least  75  watts  per 
machine.  Not  only  must  the  light  fall  on  horizontal 
surfaces,  but  on  inclined  surfaces  as  well. 

Looms — Shadows  are  the  chief  fault  of  the  light- 
ing of  looms.  Two  general  arrangements  of  outlets 
have  been  used,  as  shown  in  Fig.  7.  Plan  A  involves 
less  wiring  costs  and,  unless  the  frames  are  high,  or 
the  ceilings  low,  this  arrangement  results  in  excellent 
illumination.  The  lighting  is  usually  about  four  foot- 
candles  in  the  shadows,  and  twice  that  value  out- 
side the  shadows.  In  silk  weaving  it  is  necessary  to 
see  and  tie  broken  threads,  and  whereas  a  local  lamp 
hung  close  to  the  work  will  enable  the  operator  to  do 
this,  yet  at  least  the  same  wattage  is  required  as  would 


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J       ° 

W^K,..  .,gi 


FIG.    7 — TYPICAL   PLACING  OF  OUTLETS   FOR   THE   LIGHTING   OF  LOOMS 

Plan  A — 50  watts  per  loom.  Plan  B — 60  to  75  watts  per 

loom 

be  necessary  with  a  smaller  number  of  larger  over- 
head lamps,  and  the  operating,  maintenance  and  wiring 
costs  are  no  less.  For  example,  the  mill  now  using 
Plan  A,  Fig.  7,  formerly  had  a  60  watt  (620  lumen) 
lamp  hung  over  each  machine.  The  new  arrangement 
requires  only  50  watts  per  loom,  yet  the  lumens  per 
machine  are  increased  from  620  to  650. 

Most  of  the  present  textile  mill  lighting  installa- 
tions are  relics  of  the  practice  of  carbon  filament  lamp 
days,  or  else  have,  under  the  stress  of  war  conditions, 
been  made  without  regard  to  true  economical  main- 
tenance. Like  Topsy,  they  "just  grew".  But  bigger 
profits  to  both  owners  and  workmen  must  grow  from 
lower  output  costs,  and  hence  it  is  that  the  item  of 
lighting  is  now  receiving  close  study,  tending  toward 
the  elimination  of  waste  light,  the  use  of  more  efficient 
devices  and  the  installation  of  systems  that  will,  in 
addition  to  providing  merely  some  light,  reall\'  result 
in  quick,  easy,  ample  vision. 


u8 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  fi 


THE 
ELECTRIC 
JOURNAL 


@F1IE^TM€   PATA 


NOVEMBER 
1921 


Transformers  for  Synchronous  Converters 


Transformers  are  required  for  stepping  the  voltage  of  the 
transmission  circuit  down  to  a  suitable  value  for  the  alternating- 
current  windings  of  the  synchronous  converters  used  to  supply 
the  direct  current  for  driving  railway  equipment.  They  may  be 
cither  single-phase  or  three-phase  units,  oil-insulated  self- 
cooled,  oil-insulated  water-cooled  or  air-blast.  These  types  are . 
commonly  referred  to  as  OISC,  OIWC  and  AB.  OISC  and 
OIWC  units  may  be  shipped  assembled  in  the  cases,  either  with 
or  without  oil,  or  the  core  and  coils  may  be  boxed  and  shipped 
separately. 

Where  the  transformers  are  shipped  completely  assembled, 
unpacking  consists  of  simply  removing  the  boxing  or  bracing. 
If  the  core  and  coils  are  shipped  separately  from  the  case,  they 
should  be  left  in  the  packing  cases  until  the  transformer  tanks 
have  been  placed  in  position  and  made  ready  to  receive  the 
active  elements.  This  procedure  will  afford  mechanical  protec- 
tion and  prevent  undue  absorption  of  moisture  by  the  insulation. 
In  all  cases  it  is  very  essential  that  the  windings  be  protected 
from  dampness  or  sudden  changes  in  the  temperature  of  the 


air,  which  may  cause  sweating.  An  accumulation  of  moisture 
similar  to  that  which  collects  on  a  pitcher  of  ice  water  on  a  sum- 
mer day  is  likely  to  form  on  the  unpacked  core  and  coils  if  they 
are  brought  directly  from  a  cool  store  room  into  a  warm  sub- 
station. 

Air  blast  transformers  should  be  giveri  protection  against 
exposure  to  dampness,  both  before  installation  and  after  being 
put  in  service. 

With  all  types  of  transformers,  a  careful  inspection  should 
be  made  after  the  boxing  has  been  removed,  to  make  sure  that 
no  mechanical  injurj'  has  been  sustained  during  transportation. 
This  should  include  internal  as  well  as  external  examination, 
and  should  cover  such  points  as  proper  centering  of  the  core 
and  coils  in  the  case,  suitable  spacing  between  adjacent  leads 
from  coils  to  terminal  block,  checking  to  make  sure  that  bolts 
and  nuts  are  tight,  and  search  for  any  foreign  substances,  such 
as  nails  from  the  crating. 

When  the  transformer  has  been  shipped  in  oil,  it  is  usually 
not  necessary  to  dry  the  windings.  In  such  cases  a  number  of 
samples  of  the  oil  should  be  drawn  from  the  bottom^  of  the 
case  and  tested.  If  these  tests  indicate  that  the  oil  is  in  good 
condition  and  the  foregoing  instructions  have  been  followed, 
the  transformer  may  be  put  in  service.  Should  there  be  moisture 
in  the  oil,  it  should  be  drawn  oflf  and  dehydrated.  The  insula- 
tion must  also  be  tested  and  if  it  fails  to  show  sufficient  strength. 
the  transformer  must  be  dried  out,  after  which  the  dehydrated 


oil  should  be  put  back  into  the  transformer  case  with  the  least 
possible  delay. 

Where  shipment  has  been  made  without  the  oil,  or  if  the 
transformers  are  air-blast,  it  is  necessao'  to  make  tests  of  the 
insulation  resistance.  If  these  tests  indicate  a  low  value  of 
resistance,  drying  out  must  be  resorted  to  and  maintained  until 
sufficient  insulation  strength  is  shown. 

After  the  transformer  is  ready  to  put  into  service,  it  is 
recommended  that  it  be  brought  up  to  its  normal  operating 
voltage  slowly,  so  that  any  error  in  connections,  or  other 
trouble,  may  be  discovered  before  damage  is  done.  After  opera- 
tion at  full  voltage  for  a  few  hours,  load  may  be  applied.  A 
close  check  on  temperature  should  be  made  during  the  first  few 
hours  under  load,  and  any  indications  of  undue  rise  promptly 
investigated. 

OISC  transformers  are  so  designed  that  they  will  operate 
at  their  rated  loads  without  exceeding  a  safe  temperature,  pro- 
vided the  temperature  of  the  ambient  air  does  not  exceed  40 
degrees  C.  and  the  oil  level  is  maintained  at  the  proper  height. 

The  cooling  of  OIWC  transformers  is  dependent  upon 
the  circulation  of  a  specified  amount  of  water  through  the 
cooling  coils.  The  amount  required  is  given  either  on  the  name 


FIG.   2— CORE  TYPE  TRANSFORMER 

plate  'or  on  the  diagram  of  coiniections.  Where  there  are  two 
or  more  parallel  sections  of  the  cooling  coil,  the  valves  should 
be  arranged  so  that  each  section  shows  approximately  the  same 
flow  of  water.  When  the  proper  setting  has  been  determined 
the  valves  should  be  marked  and  in  shutting  off  the  coohng 
water  only  the  main  valve  should  be  closed.  . 

Air-blast  transformers  require  a  definite  volume  of  air  per 
minute  delivered  through  the  base  of  the  housing  at  a  static 
pressure  sufficient  to  overcome  the  friction  in  the  cooling  ducts 
within  the  transformer.  The  volume  and  pressure  required  are 
given  either  on  the  name  plate  or  on  the  diagram  of  connections^ 
A  damper  is  provided  to  regulate  the  flow  of  air.  This  should 
alwavs  be  kept  closed  when  the  transformers  are  not  111  service. 
A  screen  of  approximatelv  Va  in.  mesh  should  be  provided  over 
the  air  intake.  As  this  will  require  frequent  cleaning  it  should 
be  arranged  so  that  it  can  easily  be  removed. 

It  is  apparent  from  the  foregoing  that  the  OISC.  type  is 
more  easily  installed  and  requires  less  care  in  operation  than 
either  of  the  other  Xypes.  However,  the  OIWC.  tj'pe  is  con- 
siderably cheaper  in  first  cost  than  the  OISC,  especially  in 
units  of  comparatively  large  rating. 

In  some  districts  the  restrictions  of  the  underwTiters  are 
such  as  to  make  the  cost  of  installing  oil-insulated  apparatus 
prohibitive.  In  such  cases  air-blast  construction  is  used.  OISC 
and  OIWC  types  can  be  built  for  any  supply  voltage,  but  air- 
blast  transformers  are  not  used  for  potentials  in  excess  of  25000 
volts..  E.  R.  Sampson 


November,  1921 


THE   ELECTRIC   JOURNAL 


519 


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ing  theory  or  practice  and  questions  regarding  apparatus  or 
materials  desired  for  particular  ne?ds  will  be  answered. 
Specific  data  regarding  design  or  redesign  of  individual  pieces 
of  apparatus  cannot  be  supplied  through  this  department. 


To  receive  prompt  attention  a  self-addressed,  stamped  en- 
velope should  accompany  each  query.  All  data  necessary  for 
a  complete  understanding  of  the  problem  should  be  furnished. 
A  personal  reply  is  mailed  to  each  questioner  as  soon 
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queston  is  answered  hv  an  expert  an'l  checked  by  at  least  two 
others,  a  reasonable  length  of  time  should  be  allowed  before 
expecting  a  reply. 


o 


2047 — Over  Excited  Synchronous  Mo- 
tor— I  have  difficulty  in  explaining 
the  physics  involved  in  the  synchron- 
ous motor.  It  can  be  shown  analyti- 
cally and  verified  by  experiment  that 
sufficient  over-excitation  of  a  syn- 
chronous motor  causes  the  motor  to 
fail  to  carry  its  load.  The  torque  of  a 
synchronous  motor  is  some  function 
of  the  product  of  the  armature  pole 
strength  and  the  rotor  pole  strength. 
Over  excitation  causes  the  arma- 
ture current  of  a  synchronous  mo- 
tor to  increase  above  the  value  it 
would  have  if  the  motor  operated  at 
unity  power  factor.  An  increase  in  the 
armature  current  surely  means  an  in- 
crease in  the  armature  pole  strength 
and  over  excitation  means  that  the 
rotor  poles  at  least  have  a  tendency 
to  increase  in  strength.  I  don"t  see 
physically  why  an  over  excited  syn- 
chronous motor  refuses  to  furnish  the 
necessary  torque  to  keep  it  goin,?. 

R.  E.  B.  {■e.\^ 

Throughout  the  normal  operating 
ranges  of  a  synchronous  motor,  increas- 
ing the  excitation  always  increases  the 
maximum  available,  or  pull-out  torque : 
as  an  explanation  we  refer  you  to  an 
article  on  "Principles  and  Character- 
istics of  Synchronous  Motors"  in  the 
JouRN.^L  for  March  1921,  p.  87.  Greatly 
in  excess  of  the  operating  limits,  which 
is  perhaps  to  what  you  refer,  there  are 
two  factors  which  may  cause' a  decrease 
in  torque — iirst,  saturation  of  the  poles: 
second,  the  effect  of  armature  resist- 
ance. When  the  poles  saturate,  the 
field  m.  m.  f.  is  used  up  in  forcing  the 
flux,  which  becomes  largely  leakage, 
through  the  rotor  and  poles.  In  the  case 
of  the  armature  resistance  the  input  in- 
creases as  the  first  power  of  the  im- 
phase  component  while  the  PR  loss, 
of  course,  increases  as  the  square  of  the 
current.  It  can  be  readily  seen  that  if 
the  current  increases  indefinitely,  say 
50  times  normal  current  or  more,  the 
PR  loss  may  consume  the  whole  input 
to  the  motor.  This  latter  is  the  physi- 
cal explanation  of  those  tnathematical 
diagrams  which  show  the  effect  to  vi'hich 
you  refer.  E.  e.  s. 


2048 — Three-Wire  Generators—  We 
have  installed  four  three-wire  electric 
generators,  with  ratings  of  75  kw, 
no  kw,  and  iso  kw.  The  no  kw 
machine  has  one  balance  coil,  the 
others,  two  coils  each.  We  are  desirous 
of  findmg  out  exactlv  how  ihe  un- 
balanced current  divides  in  the  balance 
coils,  whether  it  divides  equally  at  all 
times,  or  whether  it  goes  through  a 
perodic  change.  We  need  a  simplified 
explanation  of  the  balance  coil  action 
for  the  benefit  of  the  student^  as  we 
have  been  unable  to  find  a  clear  ex- 
planation in  any  available  text  book. 

c.  K.   (VA.) 


The  unbalanced  current  of  a  three- 
wire  direct-current  generator  divides 
equally  in  the  balance  coils.  In  the  case 
of  a  single-phase  balance  coil,  the  neutral 
line  is  connected  to  the  center  of  the 
lialance  coil  and  the  unbalanced  current 
divides  equally  in  the  balance  coil,  one- 
half  the  current  going  in  one  direction 
and  the  other  half  in  the  opposite  direc- 
tion, the  two  tending  to  magnetize  in 
opposite  direction.  If  this  was  not  the 
case,  the  magnetization  of  the  balance 
coil,  which  may  be  considered  simply  as 
a  transformer,  would  be  unbalanced.  In 
addition  to  the  unbalanced  current  flow- 
ing in  the  balanced  coil  there  is  super- 
imposed on  it  a  small  alternating  current 
required  for  magnetizing  the  balance  coil 
and  generating  the  necessary  counter 
e.m.f.  Fig.  a  shows  a  single-phase  balance 
coil,  the  slip  rings  being  omitted  for  the 


FIGS.  2048  (a),   (b),   (c)   and   (d). 

sake  of  simplicity,  with  the  armature  in 
a  position  such  that  the  balance  coil  con- 
nection lies  directly  under  the  commuta- 
tor brushes.  In  this  position  the  balance 
coil  has  the  maxi^num  voltage  across  its 
terminals,  i.  e.  a  voltage  equal  to  the  dir- 
ect current  voltage  on  the  outside  wires 
of  the  line.  The  center  point  of  the 
balance  coil  A  is  clearly  at  a  voltage^ 
E.  C.  Terminal  Voltage    .  j  t  1 

^=—  above  and  below 

2 

—  and  +  brushes  respectively.  Assume 
an  out  of  balance  current  of  100  amperes 
in  the  -|-  and  neutral  leads  and  zero  cur- 
rent in  the  —  lead,  the  balance  coil  may 
then  be  considered  purely  as  an  auto- 
transformer  with  an  instantaneous  value 


of  100  volts  impressed  on  its  terminals 
and  having  50  volts  from  ^  to  5  and  A 
to  C.  The  unbalanced  current  of  100 
amperes  is  circulated  through  the  +  and 
neutral  wires  by  the  voltage  from  A  to 
B,  the  current  in  the  balance  coil  A  B 
being  100  amperes.  The  balance  coil  act- 
ing as  an  autotransformer  then  requires 
a  primary  current  of  50  amperes  flowing 
through  the  balance  coil  from  B  to  C  to 
lialance  a  load  current  of  100  amperes 
minus  the  unbalanced  load  in  the  exter- 
nal circuit  flowing  from  A  to  B.  This  is 
exactly  the  principle  of  an  auto  trans- 
former which  pulls  a  balancing  current 
of  50  amperes  from  its  source  of  supply 
completely  through  the  balance  coil  to 
balance  a  load  current  of  100  amperes 
taken  from  its  middle  point  and  one  of 
its  terminals.  This  is  obviously  necessar>' 
so  that  the  load  ampere  turns  of  the  pri- 
marv  balance  the  load  ampere  turns  of 
the  secondary.  The  resulting  current 
flowing  in  the  halves  of  the  balance  coils 
are  then  A  io  B  100  amperes  and  B  to  A. 
50  amperes  giving  .'^o  amperes  resultant 
current,  and  ^  to  C  50  amperes  result- 
ant current.  Thus,  the  resultant  is  an 
equal  division  of  the  unbalanced  load 
current,  one-half  flowing  from  A  io  B 
and  one-half  from  A  to  C.  In  Fig.  b  the 
position  of  the  balance  coil  is  shown 
when  advanced  one-eighth  of  a  revolu- 
tion. For  the  sake  of  simplicity,  assume 
that  the  armature  has  the  induced  volt- 
age in  its  coils  evenly  distributed  from 
B  to  C.  Then  point  E  will  be  2%  volts 
above  C,  and  D  will  be  75  volts  above  C 
The  impressed  voltage  across  the  balance 
current  terminals  E  and  D  will  be  7.S — 
2S  =  i50voltswith  point  A  50/2=2=; volts 
above  and  below  points  E  and  D  re- 
spectively. Thus,  the  voltage  from  A  to  B 
through 'D  is  25  -1-  2^  =  SO  volts,  and 
from  A  to  B  through  £  is  75  —  25  =  50. 
The  balance  coil  still  acts  as  an  auto- 
transformer with  the  same  action  as 
shown  in  Fig.  (a")  and  still  has  the  re- 
sultant currents  of  50  amperes  from  A 
to  D  and  from  A  to  E.  The  distribution 
of  the  currents  in  the  armature  split  up 
in  accordance  with  the  relative  resistance 
of  the  circuits  EB,  EFD  and  DB.  In  Fi.g. 
(c)  the  balance  coil  is  shown  in  a  posi- 
tion half  way  between  the  brushes.  In 
this  case  there  is  z^ro  voltage  impressed 
on  the  balance  coil  terminals  E  and  D 
and  points  E.  P  and  A  are  all  50  volts 
above  and  below  C  and  B  r^spect- 
ivflv.  In  this  case  it  is  clear  that  the  dis- 
triliiition  of  the  current  is  as  shown  m 
Fip,  (c).  A  three  phaseor  a  four-phase 
arrangement  is  similar  in  action  tothe 
single-phase  arrangement  described 
above.  The  distribution  of  the  unbalance 
load  current,  being  alwavs  equallv 
divided  in  the  balance  coils.  See  Fig.  (d) 
for  two  phase  or  double  single-phase 
arrangement  having  two  balance  coils. 

H.  E.  s. 

2049 — Compounding  Gener.\tors —  \a  gy^  "d  ^  ^-^  s-Z 
are  some  compound  gencratrig  ^A^^  <^  2-  S.  §  c 
motors    connected    so    that   tiK^serg.s     -^  ^  -1  ^„ 

"  rr'SiS"'  9  ...  ~  ^       s 


520 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  n 


field  opposes  that  of  the  shunt  and  on 
others  it  assists?  G.  w.  s.  (calif.) 

A  direct-current  generators  that  is 
shunt  wound  inherently  has  a  drooping 
vohage  characteristic,  i.  e.,  the  terminal 
voltage  of  the  machine  drops  oft  as  the 
load  increases.  This  is  a  result  of  the 
internal  resistance  drop  in  voltage  and 
the  decrease  in  the  resultant  flux  per 
pole  caused  by  the  armature  reaction.  In 
a  generator  having  a  cumulative  com- 
pound winding,  the  series  coils  assist 
those  of  th;  shunt  winding  as  the  load 
increases,  thereby  compensating  or  over- 
compensating  for  the  drop  in  terminal 
voltage  caused  by  the  internal  resistance 
drop  in  voltage  together  with  the  de- 
crease in  the  resultant  flux  per  pole.  This 
type  of  generator  is  made  with  one  of 
two  purposes  in  view  : — 
I — To  give  the  effect  of  flat  com- 
pounding over  a  definite  range  of 
load,  or 
2 — To  compensate  for  resistance  drop 
in  voltage  in  the  line.  With  a  generator 
that  has  a  differential  compound  wind- 
ing, the  series  coils  oppose  those  of  the 
shunt  winding,  thereby  making  the  drop 
in  terminal  voltage  greater  than  in  a 
shunt  machine  as  the  load  increases.  This 
type  of  generator  is  seldom  used,  but  has 
been  built  with  one  of  two  purposes  in 
view : — • 

I — To  cause   the  ■  terminal   voltage   to 
drop  in  a  definite  manner  as  the  load 
is  increased,  or 
2— To  supply  constant  current  to  an 
external   circuit   of   variable    resist- 
ance. 
Motors  that  are  likely  to  be  stalled  in 
service    are     sometimes    supplied    with 
power  from  a  generator  that  has  a  dif- 
ferential compound  winding  so  that  the 
motor  will  be  protected  in  case  of  exces- 
sive overload,  i.   e.,   the  voltage  of   the 
generator  supplying  power  to  the  motor 
drops    to   zero   on    excessive   overloads. 
This   is   a   very  special  application.   Arc 
welding  is  an  example  of  constant  cur- 
lent  application  for  this  type  of  genera- 
tor.     The      special      feature      of      per- 
formance    that     distinguishes     between 
scries,    shunt   and   compound   motors   is 
the  speed  characteristic,  or  the  change  in 
speed  with  the  change  in  load.  At  con- 
stant applied  voltage,  this  change  is  de- 
pendent upon   the  change  in  the  result- 
ant flux  per  pole  as  the  load  changes, 
and  on  the   internal   resistance  drop  in 
voltage.    Most   shunt    motors   inherently 
have  a  slight  drooping  characteristic,  i.  e., 
the  speed  drops  off  as  the  load  increases, 
because  of  the  internal  resistance  drop  in 
voltage.   The    decrease   in    the   resultant 
flux  per  pole,   caused   by   armature   re- 
action, tends  to  increase  the  speed  as  the 
load  increases,  but  is  not  usually,  strong 
enough  to  counterbalance  the  effect  of 
in  voltage, 
that  has  a 
ig   lend   to 
)cr   pole  as 
.  the  speed 
aster    than 
i     type     of 
■p  in  speed 
.    giving    a 
lad  than  a 
racteristics 
age  of  this 
Dtor  is  that 
he   load  is 
motor  that 
1    winding 
er  pole  as 
es  winding 
ain  a  con- 


stant speed  characteristic,  which  is  the 
one  reason  for  using  this  type  of  motor. 
A  motor  with  a  differential  compound 
winding  is  rarely  used,  because  the  speed 
of  shunt  motors  is  so  nearly  constant 
from  no  load  to  full  load  that  the  extra 
complication  of  a  series  winding  is 
seldom  necessary.  H.  B.  W. 

2050 — Boosting  Three-phase  Circuit — 

What    is    the    method    employed    for 

boosting    a    three-phase    circuit.    Give 

references  as  to  detailed  exposition  on 

same.  Is  the  method  outlined  in  Fig. 

(a)  practical?  w.  w.  c.  (wise.) 

The    best    way   to    boost   the   voltage 

circuit    is    by    means    of    a    three-phase 

induction    regulator.    The    voltage    can 

be     boosted     by     means     of     a     three 

phase  booster  transformer  connected  as 

per  Fig.  (b).  (See  Standard  Handbook, 


kv-a  axis.  Then,  with  zero  field  current 
the  machine  is  drawing  its  excitation 
from  the  line  as  indicated  by  the  lagging 
current  XY  in  Figs,  (a)  and  (b).  The 
amount  of  this  lagging  current  is  just 
enough  to  produce  sufficient  excitation 
(armature  ampere-turns)  and  reactance 
voltage,  to  make  the  generated  voltage 
plus  the  reactance  voltage  of  the  machine 
(neglecting  PR  drop)  equal  to  the  ap- 
plied line  voltage.  Now,  if  the  field  is 
excited  such  that  its  excitation  is  in  the- 
same  direction  as  the  armature  excita- 
tion, less  armature  exciting  and  hence, 
lagging  current  from  the  line  will  be 
necessary  to  obtain  the  balance  between 
the  generated  voltages  of  the  machine 
and  the  line  voltage  as  mentioned  above 
Further  increase  in  the  exciting  current 
will  cause  the  lagging  armature  current 
to  continue  to  decrease  until  the  point  is 
reached  when  the  field  excitation  is  just 
sufficient  to  cause  the  machine  to  gener- 
ate a  voltage  equal  to  the  line  voltage. 
The  power-factor  of  the  machine  at  this 
point  will  be  unity  and  its  armature  cur- 
rent is  a  minimum.  If  the  exciting  cur- 
rent is  increased  beyond  this  point  an 
excitation  will  be  produced  which  is 
greater  than  necessary  for  the  machine 
to  generate  the  required  counter  voltage. 
Therefore,  a  leading  current  will  be 
drawn  from  the  line  to  oppose  the  field 
excitation  and  give  a  resultant  excitation 
just  ^uflicient  to  generate  the  if  quired 
counter  voltage.  The  action  of  the  con- 
denser in  this  case  is  as  shown  in  Fig. 
(a).  Now,  if  the  machine  nulls  in  step 
relative  to  the  armature  such  that  when 
the  field  is  excited  its  excitation  opnoses 
that  of  the  armature  (i.  e.  the  field  is  re- 


^^/^v \AA/VV — ' 

\\  A^        "-^WvN        ' — \AAA 

ibl 

FIGS.  2050  (a)  and  (t) 

fourth  edition,  pp.  1014-5).  The  scheme 
shown  in  Fig  (a)  will  not  work  for, 
when  the  generator  switch  is  open,  the 
scries  transformer  has  open  circuited 
secondaries,  and  would  produce  high  re- 
actance in  series  with  the  line.  If  the 
generator  switch  was  kept  closed  and  its 
field  strength  varied  to  give  different  de- 
grees of  boosting,  then  the  scheme  will 
operate.  j.  f.  p. 

2051--SVNCH110NOUS  Condenser—  We 
have  a  2000  kv-a,  three-phase,  50  cycle, 
3300  volt,  350  amperes,  600  r.  p.  m.  self- 
starting  sNnchronous  condenser.  A  126 
volt,  170  ampere  exciter  direct  coupled 
furnishes  the  exciting  current.  Under 
ordinarj'  starting  conditions,  when  the 
excited  current  is  increased  gradually, 
the  lagging  currents  decrease,  from 
starting  amperes,  to  zero,  hence  lead- 
ing currents  increase  as  shown  in  Fig. 
(a).  However,  sometimes,  quite  the 
reverse  phenomenon  takes  place.  The 
lagging  currents  increase  from  the 
starting  current  of  220  ampcrey,  simul- 
taneous!}' with  the  gradual  increase  of 
exciting  current.  When  the  lagging 
currents  have  increased  to  450  amperes 
they  take  a  sudden  drop  to  zero  as 
shown  in  Fig.  (b).  Will  greatly  appre- 
ciate an  explanation  as  to  what  causes 
the  reverse  phenomenon. 

s.  G.  (japan.) 
Since  no  value  of  exciting  current  is 

given  in  Figs,  (a)  and  (b)  it  is  assumed 
that  the  exciting  current  is  zero  at  the 


(a)   and   (b) 


versed)  more  armature  excitation  and 
hence  lagging  current  will  be  required 
for  the  machine  to  generate  the  neces- 
sary counter  voltage.  Further  increase  in 
the  exciting  current  will  tend  to  further 
decrease  the  excitation  and  more  lagging 
current  will  be  required  to  maintain  a 
constant  generated  voltage.  The  lagging 
current  will  continue  to  increase  with 
increase  in  exciting  current,  until  a  point 
is  reached  where  the  rotor  lags  with  re- 
spect to  the  armature,  due  to  the  energy 
load  required  by  the  losses  in  the 
machine,  to  such  an  extent  that  it 
actually  slips  a  pole  with  respect  to  the 
armature,  i.  c.  it  will  be  180  degrees  from 
its  former  position.  Then  the  field  ex- 
citation and  the  armature  excitation  will 
be  in  the  same  direction.  Therefore,  less 
armature  excitation  and  hence  lagging 
current  will  be  required.  Then  further 
increase  in  exciting  current  will  cause 
the  lagging  current  to  continue  to  de- 
crease or,  if  before  the  machine  slipped 
a  pole,  the  field  excitation  had  been  in- 
creased to  a  point  equal  to  or  greater 
than  that  now  required  at  unity  power- 
factor,  further  increase  in  exciting  cur- 
rent would  cause  an  increase  in  leading 
current.  The  action  of  the  condenser  in 
this  case  corresponds  to  that  shown  in 
Fig.  (b).  The  sudden  change  in  armature 
current  from  lagging  to  practically  zero 
or  leading  current  in  Fig.  (b)  corre- 
sponds to  the  point  where  the  machine 
slips  a  pole.  m.  w.  s. 


November,  1921 


THE  ELECTRIC  JOURNAL 


521 


2052 — Winding  Factors  For  Reconnect- 
ing Induction  Motors — How  are  the 
winding  factors  obtained,  used  in 
changing  an  induction  motor  from  two 
phase  to  three  phase  and  vice  versa.  A 
two-phase  motor  reconnected  for  three 
phase  should  be  run  on  120  percent  of 
normal  voltage  in  order  to  give  the 
same  operating  characteristics  that  it 
had  before,  or  in  other  words,  if  run 
on  normal  voltage  it  will  exhibit  all 
the  symptoms  of  a  motor  operating  at 
20  percent  under  voltage.  Conversely, 
a  three-phase  motor  rewound  for  two 
phase  should  be  run  at  75  percent  of 
normal  voltage.  I  am  unable  to  see 
how  the  factors  given  in  the  above 
paragraph  are  obtained.  In  the  follow- 
ing practical  example  I  have  shown  the 
method  in  which  I  would  determine 
these  constants.  Please  check  over  mv 
work  and  point  out  the  error.  Assume 
a  motor  having  the  following  charac- 


(a)  (b) 

FIGS.  2052  (a)  and  (6) 

teristics ;  440  volts,  two  phase,  y2  slots. 
72  coils,  12  groups,  6  coils  per  group, 
groups  connected  in  series.  To  make 
this  motor  operate  on  three  phase,  the 
coils  are  regrouped  making  18  groups 
of  4  coils  per  group.  Under  two  phase 
conditions  440  volts  are  impressed 
across  36  coils  or  the  voltage  per  coil 
is  12.2  volts.  If  the  motor  is  connected 
star  for  three  phase,  each  phase  will 
consist  of  24  coils,  or  the  voltage  which 
could  be  applied  to  each  phase  would 
be  24  X  12.2  or  293  volts.  The  line 
voltage  would  therefore  be  1.73  X  293 
or  507  volts.  From  these  calculations  it 
would  seem  that  the  machine  should  b*" 
operated  on  115  percent  instead  of  120 
percent  of  normal  voltage. 

E.  w.  .s.  (pa.) 
You  have  neglected  the  phase  distribu- 
tion factor,  which  is  the  factor  which 
corrects  for  the  different  coils  in  series 
per  group  being  slightly  out  of  phase. 
Graphically  this  is  the  relation  of  the 
chord  to  the  circumference  or  the  ap- 
proximate arc  of  the  angle  of  phase  belt 
span  as  shown  in  Figs,  (a)  and  (b). 
2X12 

TT      =o.goo  for  two  phase 

3 

— ^  0.955  for  three  phase 

This  factor  is  0.900  for  two  phase  and 
0.955  for  three  phase  for  a  large  number 
of  slots  per  phase  per  pole  and  is  ap- 
proximately correct  for  any  number  of 
slots  per  phase  per  pole  above  two.  The 
factor  in  changing  from  two  to  three 
phase  star  then  becomes 

/X  ?X^jXo.9':';X£'-2pb..e_     ,,.  p  „ 

o.goo  '"'       -'"""<■ 

T.  P.  K. 

2053 — Tr.\nsformer  Connections —  We 
have  three  60000  volts,  single  phase 
transformers  designed  for  a  delta  con- 
nected system.  Would  these  transform- 
ers operate  satisfactorily  and  safely  at 
100 000  volts  if  connected  star?  Can 
the  ordinan.-  service  transformers  pri- 
mary 2200,  secondary  220/110  be  con- 
nected star  to  3800  volts. 

R.  H.  N.  L.   (b.  c.) 
For   a   delta   connected   system   under 


normal  balanced  conditions,  the  voltage 
of  each  line  above  ground  is  approxi- 
mately 58  percent  of  the  delta  vc5Ttage. 
Wheri  connected  in  star  with  grounded 
neutral,  one  end  of  the  winding  is  100 
percent  of  the  delta  voltage  above 
ground.  In  addition,  the  switching  and 
other  surges  are  higher  for  the  star  con- 
nected system.  2200  volt  transformers  are 
designed  for  use  on  either  the  delta  or 
grounded  star  system,  as  this  entails  no 
material  increase  in  cost.  60000  volt 
transformers  are  designed  for  the  parti- 
cular service,  as  the  difference  in  cost  is 
an  appreciable  amount.  The  factor  of 
safety  for  a  delta  connected  60000  volt 
design  used  for  star  connection  with 
neutral  grounded  would  be  reduced  be- 
low safe  limits.  G.  A.  B. 

2054 — Turbine-driven  Generators —  We 
have  a  7.5  kw,  four-pole,  commutating 
pole,  250  volt,  3600  r.  p.  m.  generator 
directly  connected  to  a  steam  turbine. 
The  armature  has  III  bars  and  28 
coils ;  each  coil  containing  four  circuits 
wound  as  shown  in  Fig.  (a).  That  is 
three  circuits  have  two  turns  and  one 
circuit  has  but  a  single  turn.  In  general 
why  is  this  coil  made  up  with  the 
single  turn?  The  company  representa- 
tive said  this  was  a  peculiarity  of  gen- 
erators designed  for  turbines. 

G.  w.  s.  (calif.) 
The  armature  evidently  has  seven 
turns  per  slot  and  28  slots,  or  a  total  of 
196  turns  on  the  armature.  Since  there 
are  only  in  bars  instead  of  112,  one  slot 
has  only  three  coils  brought  out,  leaving 
either  a  one-turn  coil  or  a  two-turn  coil 
dead.  The  total  effective  turns  then  must 
be  194  or  195,  approximately.  This 
number  of  turns  could  be  made  by  using 
33  slots,  99  bars,  2  turns  per  bar  (total  of 
198  effective  turns  on  the  armature).  The 
manufacturer  has  probably  considered 
that  the  operation  of  the  machine  as 
shipped  would  be  satisfacton.-,  and  has 
had  some  manufacturing  reason  for  re- 
taining the  use  of  the  28  slot  core  or  the 
III  bar  armature  or  both.  Possible  they 


FIG.  2054  (a) 

had  been  already  developed  and  a  33 
slot  core  and  a  99  bar  commutator  would 
require  expensive  development.  The 
deciding  factor  probably  was  expediency, 
not  electrical  performance.  The  odd 
winding  is  not  a  universal  peculiarity  of 
generators  designed  for  turbines.  In  fact, 
few  turbogenerators  use  such  a  wnding. 
s.  H 

2055 — Cross-connected  Current  Trans- 
formers—Explain  two  current  trans- 
formers connected  as  shown  in  Fig. 
(a)  (cross  connected).  Give  formula 
for  trip  coil  current  in  trip  coii.  What 
class  of  work  is  this  used  for?  What  is 
the  advantage  or  disadvantage  in  hav- 
ing the  two  current  transformers  in 
parallel?  R.  H.  N.  L.  (b.  c.) 

This  connection  passes  through  the 
trip  coil  a  current  composed  of  two  com- 
ponents, one  from  current  transformer  A 
and  the  other  from  current  transformer 
C.  For  three-phase  three-wire  systems 
and  balanced  load,  this  resultant  current 
through  the  coil  is  V3  times  the  current 
in   either  transformer   secondary,   at  30 


degrees  time  phase  from  either  of  the 
components,  and  at  unity  power-factor  it 
is  in  phase,  or  in  phase  opposition,  to  the 
voltage  between  lines  A  and  C.  Fig.  (b) 
is  a  vector  diagram  for  this  condition  in 
which  £aii,  £nc,  and  £ca  are  the  volt- 
ages between  the  lines,  Ik,  /b  and  /c  arc 
the  line  currents,  and  /i  the  trip  coil  cur- 
rent, the  formulae  for  the  trip  coil  cur- 
rent, /t  is:— 

lt=  V~!a  +  Id'  +  2/a/c  sin  (30°  +  9a 
— Sc) 

In  w'hich  0a  and  8c  are  the  angles  of  lag 
of  currents  /a  and  /c  respectively.  When 
the  angle  of  lag  is  the  same  for  both 
currents  sin  (30°  +  0a  —  Sc)  reduces  to 
sin  30°  or  ^  and  the  equation  becomes : — 

/t  =  1  LT+^fc'^+Tjc 
When  /a  is  equal  to  /o  the  equation  re- 
duces to  /t  =  1  3/a'=  I  3  X  /a 
This  connection  is  used  where  it  is 
desired  to  protect  a  three-phase  three- 
wire  line  with  only  one  available  trip 
coil.  Its  disadvantage  is  that  accurate 
single  wire  overload  settings  cannot  be 
obtained  because  the  trip  coil  current 
does  not  increase  in  direct  proportion  to 
the  line  current  in  the  case  of  single 
phase  overloads  or  short  circuits.  This 
may  be  better  understood  by  reference 
to  the  vector  diagram  Fig.  (c)  in  which 
/a  is  shown  twice  the  length  of  /a  but 
/•r  is  only  about  50  percent  greater  than 


FIGS.  2055  (")•  W,  (c),  (d)  and  (e) 

It.  This  connection  is  used  in  voltage 
regulator  work,  also,  when  it  is  desired 
to  obtain  a  current  vector  in  phase  with 
the  voltage  vector  for  use  with  an  in- 
ductive drop  compensator.  The  power  in 
a  three-phase  three-wire  circuit  may  be 
measured  with  a  single-phase  wattmeter 
by  the  use  of  this  connection  when  the 
three-phase  load  is  balanced : —  See 
article  by  J.  C.  Group  in  The  Electric 
Journal,  April  1920  issue.  Figs.  52,  53 
and  SA-  The  parallel  comiection  between 
two  current  transformers  is  never  used 
as  no  advantage  is  obtained  and  protec- 
tion is  sacrificed.  Referring  to  Fig.  (d) 
and  (e)  it  will  be  seen  that  in  case  of 
short  circuit  between  lines  i  and  3,  cur- 
rent /i  will  then  be  equal  to_  current  h 
(short  circuit  currents  in  this  case  are 
expressed  as  /isc  and  /asc),  but  180  de- 
grees out  of  phase  with  it.  As  the  current 
in  line  3  is  then  in  phase  with  its  voltage 
£3-,,  the  current  in  the  trip  coil  which 
is  the  resultant  of  hsc  and  /iso  is  now- 
equal  to  zero  and  the  trip  coil  will  not 
operate.  M.  R.  &  L.  N.  c. 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  II 


2056 — Phasing  Out  Syxchronous 
Motors — If  a  synchronous  motor  is 
started  from  the  alternating-current 
side  and  brings  up  a  motor-generator 
set  in  one  direction;  and  starting  the 
motor-generator  set  from  the  direct- 
current  side  brings  the  set  to  speed  in 
the  same  direction,  does  it  denote  that 
the  phasing  is  correct? 

G.  H.  (Calif.) 
If  the  direct-current  machines  were 
excited  from  the  same  bus,  both  when 
running  as  a  motor  and  as  a  generator, 
the  phasing  is  correct.  If  the  machines, 
operating  separately,  start  in  different 
directions,  simply  reverse  the  direct-cur- 
rent generator  field.  Such  a  test  can  not 
be  relied  upon  entirely,  and  it  is  good 
practice  to  check  up  the  voltage,  both  in 
value  and  direction,  each  time  a  direct- 
current  generator  is  paralleled  with  the 
lines.  K-  B.  s. 

2057 — Effect  of  Interchanging  Leads— 
Please  discuss  the  effect  produced  in 
a  two-phase  or  three-phase  generator 
when  the  leads  to  the  field  winding  are 
reversed;  would  such  a  change  neces- 
sitate "phasing-out"  a  generator  before 
attempting  to  parallel  it  with  others 
with  which  it  had  previously  been 
operated  in  parallel.  Discuss  the  same 
condition  for  the  case  of  two  genera- 
tors premanently  coupled  mechanically. 

c.  S.  (QUEREC) 
Consider  two  alternators  operating  in 
parallel.  They  are  running  at  the  sarne 
frequency  (and  also  the  same  speed  if 
the  number  of  poles  is  the  same)  and 
their  voltages  are  equal,  both  in  phase 
and  magnitude.  If  the  field  excitation  on 
one  machine  is  reversed,  its  voltage  wdll 
be  reversed  or  180  degrees  out  of  phase 
with  the  voltage  of  the  other  machine. 
This  means  that  the  rotor  of  one  machine 
must  shift  an  amount  corresponding  to 
180  electrical  degrees,  in  order  to  satisfy 
the  conditions  for  parallel  operation.  If 
the  machines  had  the  same  number  of 
poles  and  they  were  set  up  with  their 
shafts  in  line  and  end  to  end,  it  would 
simply  mean  that  after  the  field  was  re- 
versed on  one  machine,  a  pole  which  had 
formerly  been  a  south  pole,  and  lined  up 
mechanically  with  a  south  pole  on  the 
other  machine,  would  now  be  a  north 
pole  and  the  rotor  would  change  its  rela- 
tive position  so  that  this  north  pole 
would  line  up  mechanically  with  a  north 
pole  on  the  other  machine.  In  other 
words,  the  machines  could  still  be  oper- 
ating in  parallel  after  the  field  on  one 
was  reversed,  although  the  relative 
mech.-.nical  position  of  the  two  rotors 
would  be  shifted  by  an  amount  corre- 
sponding to  180  electrical  degrees.  This 
shift  might  be  anv  amount  that  is  a  mul- 
tiple of  a  pole  pitch.  It  would  not  be  nec- 
cssarv-  to  "phase-out"  the  machine.  Re- 
versing the  field  excitation  does  not 
change  the  relative  phase  position  of  the 
voltages  in  a  polyphase  machine.  It  mere- 
ly reverses  all  of  them  and  the  relative 
position  is  unchanged.  In  the  case  of  two 
generators  rigidly  coupled,  the  relative 
mechanical  position  of  the  two  rotors 
cannot  be  shifted  as  discussed  above. 
Therefore,  the  fields  of  the  two  genera- 
tors must  be  excited  so  that  their  volt- 
ages will  be  in  the  same  direction  or  ir 
fliase.  Hence,  wii'  the  excitation  on  the 
two  machines  such  that  the  two  ar? 
operating  satisfactorily  in  parallel,  thev 
cannot  be  ooerated  in  oarallel  if  the  field 
excitation    is    reversed   on   one   machine 


only.   Reversing   the   excitation   of   both 
machines      would,      of      course.      make 
the    ;elative    i.'ndition    same    as    be''oie 
and  they  cou'd  be  operated  in  parallel. 
M.  w.  s. 

2058 — Amalgam.vtion  of  Mercury  in 
Ampere-Hour  Meters —  We  have 
trouble  with  the  mercury  in  these 
meters  getting  thick,  appearing  to 
amalgamate  with  the  copper  disc.  Is 
this  an  inherent  fault  with  these  meters 
or  is  it  caused  by  too  heavy  currents 
being  sent  through  the  meter.  The 
meters  are  on  electric  trucks  and  give 
only  a  few  months  service.  In  repair- 
ing these  meters  new  mercurj-  has  been 
used,  which  I  suppose  is  the  only 
remedy.  E.  M.  M.  (Calif.) 

Mercury  meters,  when  subjected  to  ex- 
tremely high  overloads,  in  addition  to 
considerably  increased  temperatures,  are 
alTected  somewhat  by  dross  formation 
in  the  mercury  chamber.  This  is  especial- 
ly true  on  electric  trucks  where  the  vi- 
bration is  severe  and  the  loads  very  high. 
About  the  only  remedy  in  this  case  is  to 
clean  the  mercun,-  thoroughly  or  supply 
new  mercury  to  the  mercury  chamber. 
F.  c.  H. 

2059 — Unii.\lanced  Load  for  Three- 
Phase  Generator — Can  a  three-phase 
generator  supply  current  to  three 
single-phase  lines,  the  load,  varying 
from  zero  to  full  load  on  any  phase? 
I  f  not,  why  not  ?  I  understand  a  three- 
phase  generator  must  be  as  nearly 
balanced  as  possible  on  all  phases  to 
operate  properly.  E.  s.  (III.) 

The  extent  to  which  a  three-phase 
generator  can  be  used  forsupplying  three 
separate  single-phase  lines  is  determined 
principally  by  the  degree  of  voltage  un- 
balanced which  can  be  tolerated.  With 
unequal  loads  and  power-factors  on  the 
three  phases,  the  voltage  drop  in  each 
phase  is  different  from  that  of  the 
others,  and  the  terminal  voltages  are 
therefore  unequal,  .^n  attempt  to  raise 
the  lowest  of  the  three  voltages,  by  in- 
creased excitation,  will  result  in  an  equal 
percentage  increase  in  all  three  voltages. 
.\  three-phase  machine  supplying  one 
single-phase  circuit  is  an  extreme  case 
of  unbalanced  load  and  the  voltages  of 
the  three  phases  may  be  widely  different. 
A  generator  that  is  subjected  to  un- 
balanced loads  to  any  considerable  extent 
or  that  is  operated  single-phase  should 
be  equipped  with  a  damper  winding. 
Without  a  damper  winding,  heating  of 
the  machine  will  take  place,  which  may 
determine  the  limit  of  operation  under 
these  conditions.  Distortion  of  the  volt- 
age wave  form,  particularly  of  the  volt- 
age from  terminal  to  neutral,  will  also 
result.  Sec  "Comparative  Capacities  of 
.A.lternators  for  Polvnhase  and  Singlc- 
. Phase  Currents"  in  Electric  Engineering 
Papers  bv  B.  G.  Lamme.  or  in  the 
Journal  for  Aug.  191 1,  p.  672.         0.  c. 

2060 — Electric  Furnaces  For  Refining 
Steel — I  would  appreciate  vour  best 
advice  as  to  a  method  used  for  the 
final  refining  of  molten  steel  with  elec- 
tric current  after  it  is  taken  from  the 
converter.  Could  this  be  done  with- 
out the  use  of  a  complete  electric  fur- 
nace? What  book  would  you  recom- 
mend on  electric  furnaces  and  steel 
refinery  by  electricitj'? 

D.  G.  G.  (Wisconsin) 
It  is  hardly  feasible  to  attempt  to  re- 
fine converter  steel  without  using  a  com- 


plete tilting-type  electric  furnace,  for  it 
is  necessary  to  pour  off  one  of  more 
slags,  which  means  that  the  furnace 
must  be  capable  of  being  tilted,  must  be 
equipped  with  electrical  apparatus  for 
the  proper  supply  of  voltage  and  current, 
and  should  be  equipped  with  automatic 
regulators.  It  is.  however,  true  that  a 
furnace  merely  for  refining  hot  metal 
from  the  converter  need  not  be  so  high- 
ly powered  as  a  furnace  which  is  ex- 
pected to  melt  down  cold  scrap  and  then  , 
refine  the  metal.  We  recommend  the 
latest  edition  of  .Stansfield's  "Electric 
Furnaces".  w.  e.  m. 

2061 — Bronze  Dei-osited  on  Collector 
Ring  Brushes — In  the  field  circuits  of 
our  generators  we  have  collector  rings 
of  bronze  with  12  Speer  Highgrade 
brushes  %  in.  by  1/5  in.  on  each.  The 
exciter  rating  is  480  amperes  at  full 
load.  The  negative  rings  only  are  sub- 
ject to  considerable  wear  and  bronze 
is  deposited  in  patches  on  the  contact 
face  of  the  brushes,  although  the  sur- 
rounding carbon  remains  in  contact 
with  the  ring.  There  is  no  sparking  or 
excessive  heating  under  the  moderate 
load  conditions.  In  the  case  of  a  direct- 
current  generator,  I  understand,  the 
presence  of  this  "picked  copper"  re- 
duced the  brush  contact  resistance, 
permitting  local  current  in  the  short- 
circuited  coil  thereby  increasing  the 
heating  of  the  commutator  and 
brushes.  In  the  case  of  the  collector 
ring  is  its  presence  detrimental?  Are 
the  brushes  too  abrasive?  Does  f re- 
fluent dressing  of  the  contact  surface 
of  the  brushes  increase  the  abrasive 
action?  Can  you  suggest  a  remedy' 
The  positive  collector  rings  and 
brushes  remain  in  perfect  condition, 
w.  A.  p.  (Ontario) 

Your  question  indicates  that  the 
brushes  are  operated  at  very  modcrati? 
densities,  and  presumably  at  moderate 
collector  ring  speeds,  and  it  seems,  there- 
fore, that  the  trouble  is  probably  caused 
l)y  some  local  condition.  We  suggest, 
first  of  all,  that  the  brushes  and  brush- 
rigging  be  inspected,  to  see  if  there  is 
any  appreciable  vibration.  Vibration  pre- 
vents good  contact  between  brush  and 
ring,  and  will  often  start  burning,  which 
might  deposit  copper  on  the  brushes.  A 
similar  effect  might  be  produced  if  the 
brush  pressure  is  low,  or  not  uniform. 
Two  pounds  per  square  inch  pressure, 
which  in  this  case  would  mean  practical- 
ly two  pounds  per  brush,  has  been  found 
quite  satisfacton,-.  All  brushes  should  be 
checked  up  to  see  that  the  pressure  is 
correct.  It  has  been  foimd  that  oil  or 
grease  used  as  a  collcrlor  rinj?  lubricant, 
or  the  leakage  of  oil  from  a  bearing  to 
the  ring,  mav  cause  the  brushes  to  pick 
up  copper.  This  might  be  investigated. 
It  IS  suggested  that  the  occasional  re- 
versal of  generator  excitation  to  alter- 
nate the  polarity  of  the  rings  might  re- 
duce this  trouble  if  it  still  persists.  How- 
ever, if  the  three  causes  mentioned  above 
are  eliminated,  there  seems  to  be  no 
reason  why  satisfactory  operation  should 
not  be  insured.  Frequent  dressing  of 
the  brush  contact  surface  with  emery 
cloth  need  not  increase  the  abrasive 
action  if  all  the  emerv  particles  arc  care- 
fully blown  out.  and  the  brush  surface 
wiped.  The  condition  of  the  positive  col- 
lector ring  suggests  that  the  trouble  is 
not  due  to  the  nattiral  abrasiveness  of 
the  brush.  E.  n.  s. 


December,  1921 


THE  ELECTRIC  JOURNAL 


J?  5?] 


99 


(  PATENTED) 

A  "saving"  affecting  first  cost  is  not 
always  an  "economy"  as  determined 
by  the  effect  upon  last  cost.  Cheap- 
ness and  service  seldom  go  hand  in 
hand.  Fractional  h.  p.  motors  really 
deserving  of  the  term  "better,"  carry 
"HSEfiifl"  Precision  Bearings  as  stand- 
ard. 'mBShSr  Quality  helps  make 
them  "better." 

See  that  your  fractional  h.  p.  motors 
are  'NORmfl"  equipped 


Ibmj  Iskiiiidl  ©to 
Ball, Roller, Thrust  and  Combination  Bearings 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  12 


Benjaixxin 

EUipUcal  An^le 

R^tlecioT  Sockei 


FOR  the  illumination  of  vertical  surfaces, 
where  high  visibility  without  glare  or 
deep  shadows  is   desirable,  Benjamin 
Elliptical  Angle  Reflector  Sockets  are  pe- 
culiarly adaptable. 

The  installation  in  the  switch-room  of  the 
power  station  of  the  great  nitrate  plant 
at  Nitro,  W.  Va.,  illustrated  below,  is  typical 
of  the  utility  of  the  elliptical  angle  reflector. 

These  units  were  selected  by  the  J.  G. 
White  Engineering  Corporation,New  York, 
because  of  the  peculiar  adaptability  of  the 
unit  for  the  service  required.  Other  emi- 
nent engineers  also  have  specified  them  for 
the  illumination  of  warehouses,  loading 
platforms;  of  side-wall  and  outdoor  sign 
lighting,  and  of  many  difficult  and  unusual 
places  in  factory  and  mill  structures. 

We  are  always  glad  to  cooperate  with 
engineers  in  developing  specifications  for 
the  installation  of  Benjamin  Industrial 
Reflectors  to  achieve  Correct  Industrial 
Lighting. 

Write  to  nearest  office  for 
full  information 

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NEW  YORK  CHICAGO 

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December,  1921  THE   ELECTRIC  JOURNAL 


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TABLE  OF  CONTENTS  FOR  DECEMBER,  1921 

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^  ^iiiiiiMiiiiiMiiiiiiuiiiUHiiMiiiiiiiiiiuiinniiiiMiiiiiiriiiniiiiiiiiMiiiiiiiMiiiiiiiiMiiiiiiiniiniiuiiiniiiiuiiiniiiiiiiiiiiniiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiMiiiiHiiiiiiiMiiiiiiiii^  = 


EDITORIAL 

The  Development  of  Our  Water  Powers A.  L.  Schiebcr 523 


ARTICLES 


Hydraulic  Reaction  Turbines D.  J.  McCormack 524 

Circle  Diagrams  for  Transmission  Systems R.  D.  'Evans  &, 

H.  K.  Sells 530 

A  Dry  Cell  Radio  Vacuum  Tube Harry  31.  Ryder 536 

Changing  Railway  Substations  from  25  to  60  Cycles  ...G.  C.  Hecker 539 

Phase  Modifier  for  Voltage  Control Wm.  Nesbit 542 

Methods  of  Magnetic  Testing T.  Spooner 548 

Commutator  Insulation  Failures ,/.  L.  Rylandcr 554 

Railway  Operating  Data 556 

The  Journal  Question  Box 557 


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THE  ELECTRIC  JOURNAL 


Vol.  XVIir,  No.  12 


The  Wellman-Seaver- Morgan  Co. 

CLEVELAND,   OHIO 

Designers  and  builders  of  Hydraulic  Turbines 
for  all  capacities 

In  physical  size  of  units  and  horse-powers,  we  have  led  in  the 
progress  of  recent  years.  We  have  established  a  high  standard 
for  runner  and  overall  plant  efficiencies,  while  maintaining  our 
usual  standard  of  excellence  in  workmanship  and  materials. 
S)me  of  the  world's  foremost  achievements  in  the  hydro-electric 
held  were  pio- 
neered by  our 
highly  trained 
sta  ff  of  engi- 
neers. 


Above  we  illustrate   the  Assembly  of  Speed    Ring  and 

Turbine  for  one  of  two  units  furnished  San  Francisquito 

No.  2  Plant.  City  of  Los  Angeles.  Cal. 

Assembly    of    Steel    Spiral    Casing    shown   to  the  right 


BULLETINS  ON   REQUEST 


Designed   and   Built   to   meet    the   most   ex 


Four  Horizontal  Shaft 
Twin-  Wheel 

SMITH 

HYDRAULIC 
TURBINES 

Here  illustrated  are  developing  6550 
1  IP.  under  62  feet  head  in  the  S.U.M. 
plant  at  Paterson.  N.  J.  Each  unit  is 
direct  connected  to  a  generator,  and  is 
regulated  by  an  oil  pressure  governor. 


of    Mode 


Power   Dovelopn 


Write  Dept.    "  C  "  for  Bulletin   of  Designs  and  Hydraulic  Data 

S.  MORGAN  SMITH  CO.,  York,  Pa. 


Branch 
Offices 


■■} 


Boston 
196  Federal  Street  76 

Salt  Lake  City 
521   Mclntyre  Building 


nroe  Street 
Portland,  Cre. 
224  Pine  Street 


Citizens  and  Southern   Bank  BIdg. 


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December,  1921 


THE   ELECTRIC  JOURNAL 


Our  customers  number  some  of  the  largest  Central  Stations 
and  isolated  plants  in  the  country 


Careful  design  and  workmanship 
in  our  apparatus  has  made  pos- 
sible   these    satisfied    customers 


Do  You  Know   ELPECO   EQUIPMENT 


Outdoor  Substations 
Pole  Top    Switches 
Disconnecting  Switches 

(Indoor  and  Outdoor) 


Choke  Coils 
Bus  Supports 
Switchboards,  AC.  and  D.c. 
Switchboard  Fittings 


Send  us  your  substation  specifications  and  get  acquainted 

Bulletins  upon   request 

Electric  Power  Equipment  Corporation 


REPRESENTATIVES 


O    T.   HALL 


J.  J.  COSTELLO 
201  Devonshire  Si..  Boston,  Mass. 

DAVIS-FERGUSSON-HARRIS 

CONST.  CO 

312  N.  Harwood  Si.,  Dallas.  Tex. 

CHAS.  A.  ETEM 
9I7.A  Marquette  Ave.,    Minneapolis,  Minn 

FERRANTI  METER  &  TRANSFORMER 

MFG.  CO.,  Ltd. 

26  Noble  Street  Toronto,  Canada 


13th  and  Wood  Streets,  Philadelphia,  Pa. 


>o*SSliffil^ 


REPRESENTATIVES 


IDELPHIA.^^ 


E.  J.  PUTZELL 

203  Pan  American  Bank  Building 

New  Orleans,  La. 


E    A.  THORNWELL 
1026  Atlanta  Trust  Co.  Building 

Atlanta,  Ga. 


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THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


Super-Seasoned  Fibre 


TV /TODERN  manufacturing  conditions  de- 
^^ -^  mand  material  of  higher  efficiency  than 
ever  before. 

"S-S"  Fibre  measures  higher  in  dielectric 
strength  and  proves  its  superiority  in  every 
test  for  durability,  density,  rigidity,  hardness, 
tensional  and  torsional  strength. 

It  machines  better  and  cuts  with  cleaner 
sharper  edges  for  all  work  where  precision  is 
required. 

Our  exclusive  process  of  super- seasoning, 
ageing  and  curing  makes  "S-S"  Fibre  a  highly 
specialized  product. 

PEERLESS  INSULATION 

In  insulation  paper  electrical  resistance 
comes  first — and  among  all  papers  Peerless 
ranks  first,  being  25%  to  50%  greater  in  di- 
electric strength. 

In  our  "S-S"  Fibre  Book  you  will  find  the 
reasons  for  the  many  exceptional  qualities  of 
our  big  line  of  fibre  and  fibre  products. 


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December,  1921 


THE  ELECTRIC  JOURNAL 


7T7  iyrVB  (Z/OT7e 


ALUMINUM  CASTING 

ACHINED  AND  ASSEMBLED 

Making  the  Mold 
Pouring  the  Metal 
Breaking  the  Mold 
Cleaning  the  Casting 
Machining^S  Surfaces 
Slotting 

Drilling  — 7  Holes 
Tapping — 2  Holes 
Assembling 


QUANTITY  Production  was  Henry 
Ford's  answer  to  Hard  Times. 
Greater  Output  means  a  lower 
manufacturing  cost  per  item — smaller  sell- 
ing price — larger  sales  volume — increased 
profit.  This  may  look  like  a  long  way 
'round,  but  it's  really  a  short  way  home. 
A  few  years  ago  GilfiUan  Bros.,  of  Los 
Angeles,  Cal.,  entered  the  field  with  a  port- 
able electric  drill.  It  was  a  good  drill, 
and  they  sold  a  lot  of  them  ;  but  it  wasn't 
up  to  their  ideals  because  it  wasn't  light 
enough. 

They  made  it  of  metal 
throughout.  You  can  get  an 
idea  of  some  of  the  work  involv- 
ed by  looking  at  the  aluminum 
brush  holder  frame  reproduced 
at  the  left.  Quantity  produc- 
tion, on  turret  lathes,  had  cut 
down  the  working  time  to  ap- 
proximately 23  minutes  for  this 


x 


piece,  but  that  depended  on  the  human 
element,  and  did  not  include  hardening  in 
the  mold,  and  transfer  from  one  depart- 
ment to  another. 

Bakelite  solved  their  problem.  Look  at 
the  same  piece,  molded  in  seven  minutes, 
which  includes  hardening!  This  piece  is 
begun  and  completed  in  the  molding 
presses.  It  is  finished,  even  to  the  high 
gloss,  in  this  one  department. 

Seven  metal  inserts,  incorporated  in  the 
Bakelite,  are  turned  out  by  automatic 
screw  machinery.  This  is  only  one  more 
special  part  than  was  required  for  the 
aluminum  frame.  Bakelite  itself  being  a 
high  dielectric,  the  insulating  bushings  re- 
quired between  the  brush  holders  and  the 
metal  frame  are  now  eliminated. 

Have  you  considered  Bakelite  ?  Have 
you  thought  it  too  expensive  ?  Gilfillan 
Bros.,  in  a  highly  competitive  field,  didn't 
find  it  so. 

Why  not  let  us  go  into  details  with  you? 


GENERAL  BAKELITE  COMPANY 

TWO  RECTOR  STREET,     -     NEW  YORK,  N.  Y. 

We  welcome  inquiries  from  manufacturers,    and   maintain    a 
research  laboratory  for  the  working  out  of  new  applications. 


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THE   ELECTRIC   JOURNAL 


Vol.  XVIII,  No.  li 


Just 
Out 

The  first  adequate  book  on 
details  of  modern  switchboards 
and    other    switching   equipment 
I  by  an  acknowledged  authority  in  this  field. 

Switching  Equipment 
for    Power    Control 

By  STEPHEN  Q.  HAYES 

Switchboard  Project  Engineer 

Westinghouse  Electric  &  Manufacturing  Co. 

470  pages,  6x9,  illustrated,  $4.00  net,  postpaid 

The  book  presents  the  kind  of  informa- 
tion the  Switchboard  Operator  needs  to 
help  him  keep  the  equipment  in  his  care 
in  the  best  operating  condition. 

It  explains  what  he  should  expect  of  the 
apparatus  and   equipment. 

It  assists  him  in  the  selection  and  instal- 
lation of  new  material. 

Enough  of  the  theoretical  side  of  the 
subject  is  given  to  define  the  functions  and 
limitations  of  the  various  devices.  This 
will  aid  consulting  engineers  in  specifying 
equipment  that  can  be  readily  obtained  and 
that  will  operate  satisfactorily  under  actual 
conditions. 

Examine  this  new  book  for 
10  days  FREE 


FREE  EXAMINATION  COUPON 


You  mav  send 


New  York.  N.  Y. 

I  days'  approval: 


I  agree  to  pay  for  the  books  or  return  them  postpaid  within  lo  day 


of 


:ipt. 


Member  of  A.  I.  E.  E.? 

Signed 

Address 

Name  of  Company 

Official  Position   , 

(Books  sent  on  approval  to  retail  piircha* 
only) 


Periodic  Insulation 
Resistance  Tests 

of  Generators  and  other  Electrical  Equip- 
ment, make  it  possible  to  prevent  "trouble" 
and  serious  "breakdowns";  and  the  best  in- 
strument to  use  for  such  service  (as  shown 
above)  is  a 

MEGGER 
TESTING  SET 

Hundreds  of  well  satisfied  Megger  users  are 
employing  the  Merger  method  from  day  to 
day;  and  it  is  a  pleasure  to  be  able  to  state 
that  we  are  in  position  again  to  deliver  vari- 
ous ranges  of  both  Meggers  and  Bridge- 
Meggers  from  Philadelphia  stock. 

Write  for  New  Catalog  942 

JAMES  G.  BIDDLE 

1211-13  Arch  Street,    PHILADELPHIA 


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December,   1921 


THE   ELECTRIC   JOURNAL 


DH-16 

'Bungalow"  Type 
Air  Compressor 


for  all  classes 

of  cars 

up  to  35,000  lbs, 


WHILE    predominant    in    the  Safety   Car   field,   and   thought  of 
chiefly    perhaps     in     connection     with     that     branch     of     the 
traction   industry,   the  Westinghouse   DH-16  is  by  no  means 
adapted   exclusively   to   the   requirements  of  Safety   Cars. 

It  has  proved  equally  efficient  and  satisfactory  on  cars  of  all 
sizes  and  designs  up  to  35,000  lbs.  in  weight,  this  arbitrary  line  being 
drawn  to  set  apart  that  class  of  service  which  normally  requires  of  a 
compressor  not  more  than  16  cu.  ft.  of  air  per  minute  to  assure  ade- 
quate braking  force  and  dependable  operation. 

Hundreds  of  installations  testify  to  the  efficiency  and  economy 
of  DH-16  compressors  as  adapted  to  medium-weight,  double  truck 
cars  of   the   type   pictured   above. 

Westinghouse  Traction  Brake  Company 

General  Offices  and  Works:  Wilmerding,  Pa. 
OFFICES 

Boston,  Mass.  Los  Angeles  New  York 

Chicago,  111.  Mexico  City  Pittsburgh 

Columbus,  O.  St.  Paul,  Minn.  Washington 

Denver,  Colo.  St.  Louis,  Mo.  Seattle 

Houston,  Tex.  San  Francisco 


WestinghouseTractionBbakes 

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THE    ELECTRIC   JOURX.-IL 


Vol.  X\'III,  No.  12 


SANGAMO  METERS  1^ 

Disfribufed 
fhroudhouf 
fhe  World 


Domestic  Agents 


American  Electric  Company.  St.  Joseph.  Mo. 
Electric  Appliance  Company. 

Chicago.  New  Orleans,  San  Francisco.  Dallas. 
Federal  Sign  Company.  (Electric)  -ttwi 

Chicago.  Birmingham.  Cincinnati.  Louisville. 

Milwaukee.  Minneapolis.  New  Orleans. 
Hodgson  Electric  Appliance  Co.,  Inc..  Atlanta.  Ga. 
Ludwig  Hommel  6e  Company,  Pittsburgh.  Cleveland 


Domestic  Agents 


^angamo 
Meters 
for  Every 
Electrical 
Need 


F.  R.  Jennings  Company.  Detroit. 

Charles  A.  Milbank  Company,  Kansas  City 

Mountain  Electric  Company.  Denver. 

Rumsey  Electric  Company.  Philadelphia. 

Schiefer  Electric  Company,  Rochester.  Buffalo.  Syracuse. 

Burton  R.  Stare  Company,  Seattle. 

Wetmore  Savage  Company,  Boston. 

White  &  Converse.  Minneapolis. 


FOREIGN   AGENTS  in   Barcelona,  Brisbane,  Brussels,  Buenos  Aires,  Christchurch,   Copenhagen, 

Havana,  Ilo  Ilo,  Johannesburg,  London,   Melbourne,   Mexico  City,   Milan,   Montevideo, 

Osaka,  Paris.  Rio  de  Janeiro,  Shanghai,  Soerataya,  Sydney,  The  Hague,  Valparaiso 

Sangamo  Electric  Company  Springfield,Illinois.U.S.A. 

NEW  YORK,  CHICAGO,  ST.  LOUIS,  SAN  FRANCISCO,  LOS  ANGELES  2101  A 


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December,  1921 


THE   ELECTRIC  JOURNAL 


13 


Current  Collector  on  Brill  "Rail-less^^  Car 
an  Important  Feature 


The  Brill  Current  Collector 
was  specially  developed  to  en- 
able the  electric  rail-less  car  to 
be  operated  in  and  around  veh- 
icular traffic  with  maximum 
efficiency.  Its  two  under-wire 
sliding  shoes  engage  the  wire 
and  an  ingenious  series  of  pivots, 
in  conjunction  with  a  pole  19  ft. 


long,  permit  operation  as  far  as 
16  ft.  either  side  of  the  over- 
head wires. 

With  this  type  current  collect- 
or the  Brill  "Rail-less"  Car  may 
be  turned  within  a  diameter  of 
40  ft.  without  disengaging  the 
wires. 


A  copy  of  Brill  Bulletin  No.  254  sent  on  request 
will  give  further  details  of  this  equipment 


M  The  J.  G.  Brill  Company  il 


Pi-iiu>olDe:l-13mia.,  Pa. 


American    Car    Co.    G.C.Kuhlman  Car  Co.      —      Wason    Manfc  Co. 

st.  i.ouis    t>/10.  cl-evelamo.  ohio.  sph  i  not  1  el-d.  m  a.s£ 

Canadian  Brill  Company.  Limited.  Preston,  Ont..  Canada 


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14 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


See  this 

Library  Edition  of 

STEINMETZ 

for  10  days  FREE 

The  nine  volumes  which  Dr.  Steinnictz  has  contributed  on  the 
subject  of  electrical  engineering  are  now  available  in  a  handsome 
specially  bound  set.  To  those  who  know  what  tiicse  great 
books  have  meant  in  the  development  of  electrical  engineering 
theory  and   practice — this  announcement  needs  no  elaboration. 

Put  Steinmetz  in  your  library 

Have  this  handsome  set  witli  its  full  treatment  of  the  thcor\' 
and  special  problems  ot  electrical  engineering  at  your  command. 
The  handbook  and  the  practical  treatise  may  give  you  the  simple 
fact  you  need — but  Steinmetz  gives  vou  the  theory  and  its 
application — the  real  solution  of  the  problem. 

Keep  in  touch  with  Steinmetz 

Put  Dr.  Steinmetz's  books  in  your  library.      They   bring  you 
in  convenient  form  the  results  of  his  study  and  experimentation 
"'     ''  "         '  ing  Engineer  of  the  General  Electric  Company. 
Tiplete  presentation  of  modern  electrical  engi- 


s  Chief  Ci 
Thev  form 


;the 


Sent  on  approval.     No  money  down. 

Only  $4.00  in  10  days 

and  $4.00  monthly  for  8  months 


iiiL-  tlif   Steinmetz    Electric, 

ijays  free.     Simply  till  in  and 
ill  not  obligate  you  to  pun 


Library  for  lo  .lays  free.     Simply  till  in  and  mail  thi 
below.     T 

agree  to  return  tlie  books,  postpaid,  in  ten  da. 
S4.00  in  ten  days  and  S4.00  per  month  for  eight  nioi 
member  that  these  books  aic  the  latest  rexisioi 
Steinmetz  books  in  a  handsome  specially  boun 
edition  al  a  price  a  little  less  than  the  regular  editlo 

Get  the  Steinmetz  Set — 
and  the  Steinmetz  Habit 


FREE  EXAMINATION  COUPON 


I  McGraw-Hill  Book  Co..  Inc.,  370  Seventh  Avenue.  New  York. 

I  ^■ou  may  send  me  on  approval  for  lo  days  free  examination  tbf  Steinmetz 

I  Electrical  Engineering  Library.     1  agree  to  return  the  books,  postpaid, 

■  in  lo  days  or  to  remit  m-oo  in  lo  days  and  J4.00  per  month  for  eight  months 

j  Nante    

I 

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a  Memberot  A.  I.  E.  E.?   

B  

I  (Books  sent  on  approval  to  retail  customers  in  the  L".  S.  and   Canada 

J  only.)  K.  J.,  12-21 


Success 


THERE  is  a  steadily  growing  class 
of  manufacturers  who  are  using 
ball  bearings  on  the  shafts  and  spindles 
of  the  machines  they  build.  And  there 
are  a  great  many  who  do  not  use  them. 
Why  is  the  one  class  so  keen  for  them 
and  the  other  so  set  against  them?  The 
answer  is — because  of  their  experience 
with  ball  bearings. 

But  why  does  one  class  experience  suc- 
cess and  the  other  failure?  There  are 
obviously  two  reasons  for  this:  the  kind 
of  bearings  that  are  used,  and  the  way 
they  are  used. 

We  have  brought  about  the  shift  of  some  pretty 
important  concerns  into  the  successful  class. 
And  we  have  used  both  the  above  causes  in 
doing  so.  We  have  furnished  them  with  the 
most  successful  bearings,  and  we  have  given 
them  the  most  successful  way  of  mounting  and 
using  them. 

We  have  developed  not  only  a  highly  successful 
bearing:  we  have  developed  the  most  successful 
system  of  ball  bearing  practice  or  engineering. 

Mr.  Manufacturer,  if  you  will  lay  your  bearing 
problems  before  us,  even  if  your  experience  with 
ball  bearings  has  hitherto  been  unsuccessful,  we 
shall,  perhaps  be  able  to  initiate  you  into  the 
happy  guild  of  successful  users,  the  users  of 
GURNEY   BEARINGS 

Gurney  Ball  Bearing  Co. 

Conr^J  y,iltnl  L:ien,te 

Jamestown,  N.  Y. 


GURKEY 

BALLBEARINGS 


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December,  1921 


THE   ELECTRIC  JOURNAL 


15 


OBOI 


lOBOI 


30E10I 


THE  TEXAS  COMPANY 

announces  the  Publication 
of  a  New  Booklet. 

LUBRICATION 

OF  THE 

STEAM  TURBINE 


THIS  36  page  book  will  be  sent  on 
request,  while  they  last,  to  inter- 
ested steam  turbine  operators,  builders 
and  erecting  engineers. 

We  will  say  just  a  few  words  about  the  book- 
let so  that  we  shall  be  more  certain  that  the 
right  kind  of  people  will  ask  for  it. 

In  the  first  place  it  is  not  a  theoretical 
treatise  for  students — It  is  a  practical  dis- 
cussion for  men  who  USE  oil. 

You  will  not  find  it  in  any  "pretty"  pictures 
or  a  long  dissertation  on  the  history  of  the 
Turbine — going  way  back  to  the  ancient 
Greek  who  was  supposed  to  have  discovered 
its  principle. 

As  a  matter  of  fact,  the  first  Text  page  starts 
discussing  Lubrication  and  in  logical  se- 
quence all  the  important  items  arc  taken  up 
— such  as 

Lubricating  Methods 

Oiling  Systems 

Effects  of  Heat,  Water,  Deposits 

Cleaning 

Starting 

Oil  Coolers 

Reduction  Gears 

And  we  have  followed  the  procedure  which 
has  gained  such  nation  wide  recognition  in 
engineering  circles  for  our  Magazine  "Lub- 
rication"; that  is,  wc  have  held  all  the  adver- 
tising matter  to  the  last  pages — in  a  separate 
section — 'just  as  in  this  or  any  other  technical 


journal.  The  text  pages  are  all  "white 
meat". 

Another  thing  about  "Lubrication  of  the 
Steam  Turbine"  —  it  has  been  written  by, 
and  checked  up  by  men  who  have  observed 
lubricants  at  work  on  all  types  of  turbines, 
from  the  largest  to  the  smallest,  all  over  the 
country. 

The  book  will  fit  your  coat  pocket — it  is  in- 
teresting enough  to  be  read  at  a  sitting — im- 
portant enough  to  become  part  of  your  tech- 
nical library. 

Get  your  copy  at  once — there's  a  coupon  to  help  you 
do  it — before  some  more  immediate  claim  on  your  time 
might  cause  you  to  forget  it. 

Remember — there  is  a  Texaco  Lubricant  for  every  pur- 
pose— and  you  may  want  to  improve  the  service  of  some 
of  the  other  units  or  auxiliaries  under  your  care — Tex- 
aco Lubricants  and  Texaco  Service  will  help. 


:Coupon: 


THE  TEXAS  COMPANY 

Dept.  EJ     17  Battery  Place,     New  York  City 

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Vol.  XVIII,  No.  12 


Chiefs Ive  Found  ihe  answer" 


Westinghouse 


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December,   1921 


THE   ELECTRIC   JOURNAL 


17 


W^stinghouse 

Patented  Tuyeres 

They  Defy  Demon  Heaf 


(»(. 


The  Tuyeres  used  on 
Westinghouse  Under- 
feed Stokers  are  de- 
signed so  that  contrac- 
tion and  expansion 
caused  by  varying 
heat  intensities  will 
not  crack  them. 

This  insures  fewer  re- 
placements and  lower 
upkeep. 

Westinghouse    Electric    &    Manu- 
facturing Company 

East  Pittsburgh,  Pa. 
Sdes  Offices  in  All  Principal  Ameri- 
can   Cities 


— A  careful  consideration  of 
details  in  the  first  place  will 
mean  a  large  saving  in  the 
long  run. 


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Vol.  XVIII,  No.  12 


AoriolaSi. 

175  to  500  Meters 


$75QQ 

Complete  with  head 
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AB  Battery  and 
Antenna  outfit. 


A  Dry-Cell,  Short-Wave  RegenerativG  Roceiver^ 


A  Real  Advance  in  Radio 

Westinghouse  engineers  have  developed,  after  months 
of  study  and  research,  a  dry-cell,  short-wave  re- 
generative tube  receiver,   Aeriola,  Sr. 

The  tube  filament  of  Aeriola,  Sr.  will  operate  on  a 
single  dry  cell  and  only  a  small  20-volt  B  Battery 
is  needed  for  the  plate. 

Ask  our  nearest  dealer,  or  our  local  office  in  any  of  the 
principal  cities,  for  Folder  F-4483. 

Westinghouse  Electric  &  Manufacturing  Company 

East  Pittsburgh,    Pa. 

Westinghouse 


The  Electric  Journal 


VOL.   XVllI 


December.  1921 


No.  12 


of  Our 
Water  Powers 


It  is  generally  appreciated  that  the 
^  "®  successful  development  of  our  water 

Development  powers  merits  a  definite  place  in  our 
program  for  economic  welfare. 
Hydroelectric  development  repre- 
sents a  definite  conservation  of  our  gradually  diminish- 
ing fuel  supply,  thereby  making  it  available  for  the 
future  or  releasing  it  for  other  necessary  purposes- 

What  is  not  so  generally  known  or  appreciated, 
however,  is  the  difficult  problem  of  the  hydraulic  en- 
gineer in  providing  suitable  apparatus  to  handle  these 
natural  forces,  and  the  factors  to  be  taken  into  consid- 
eration in  their  application.  The  electrical  engineer 
has  provided  for  the  transmission  of  electrical  energy 
over  long  distances,  permitting  hydroelectric  develop- 
ments that  could  not  be  undertaken  before  the  days  of 
the  high-voltage  transmission.  Our  water  powers  are, 
therefore,  a  potential  source  of  energy,  waiting  to  be 
utilized,  but  requinng  careful  engineering  analysis  to  a 
greater  degree  than  probably  any  other  undertaking. 

A  total  of  approximately  looooooo  horse-power, 
in  hydro-electric  power  is  actually  developed  in  the 
United  States  today,  and  our  available  undeveloped 
water  powers  are  estimated  at  approximately  55  000  000 
horse-power.  While  possibly  a  large  portion  of  this 
could  not  be  undertaken  economically  at  the  present 
time,  applications  totaling  approximately  15000000 
horse-power,  have  been  filed  with  the  Federal  Water 
Power  Commission  since  the  recent  passage  of  the 
Water  Power  Bill ;  a  measure  long  needed  and  which 
has  added  a  real  stimulus  to  this  important  phase  of 
our  economic  development  by  insuring  an  equitable  ad- 
ministrative control  of  our  natural  water  power  re- 
sources. 

While  the  use  of  water  power  is  by  no  means  new, 
the  real  development  of  the  water  turbine  practically 
parallels  that  of  the  alternating-current  generator. 
The  development  has  been  two  fold,  one  of  increasing 
unit  capacity  and  speed  and  one  of  higher  efficiencies. 
Twenty-five  years  ago  units  of  5000  hp,  were  the  larg- 
est to  be  found.  Even  as  recent  as  ten  years  ago 
20000  hp  was  the  maximum,  yet  today  units  as  large 
as  50  000  hp,  have  been  built  and  are  in  successful  op- 
eration, and  definite  plans  have  been  made  for  the  in- 
stallation of  units  up  to  75  000  hp.  Efficiencies  have 
increased  from  75  and  80  percent  to  as  high  as  93  per- 
cent or  more.  This  performance,  together  with  im- 
provements in  the  present-day  electric  generator  have 


made  possible  overall  efficiencies  as  high  as  90  percent 
for  the  combined  hydroelectric  unit.  But  progress  has 
not  been  confined  to  the  larger  and  more  spectacular 
units,  as  more  efficient  and  higher  speed  wheels  are  now 
available  for  small  powers,  at  heads  as  low  as  eight 
feet,  and  are  being  utilized  by  the  hundreds.  Formerly, 
such  plants  were  not  feasible  on  account  of  the  prohibi- 
tive cost  of  development,  due  to  non-suitable  apparatus 
and  its  inefficient  operation. 

Increased  efficiency  of  hydraulic  turbines  is  of 
especial  importance  in  those  installations  where  the 
quantity  of  water  available  is  limited  during  certain 
seasons  of  the  year,  either  by  lack  of  storage  facilities, 
as  is  the  case  in  many  of  our  Western  and  Southern 
developments,  or  by  legal  restrictions,  as  at  Niagara 
Falls.  Where  a  large  amount  of  money  has  been  in- 
vested in  storage  dams  and  in  long  distance  transmis- 
sions, it  is  important  that  the  maximum  return  on  this 
investment  be  secured.  In  such  cases  an  increased 
turbine  efficiency  of  ten  percent  means  a  corresponding 
increase  in  the  power  that  can  be  generated  with  the 
same  amount  of  water,  and  this  increased  percentage 
may  mean  the  difference  between  the  financial  success 
or  failure  of  the  installation. 

The  article  on  "Hydraulic  Reaction  Turbines"  in 
this  issue  of  the  Journal  is  of  particular  interest  in 
bringing  one  to  a  realization  of  the  many  factors  to  be 
considered  in  the  successful  design  and  application  of 
the  modern  water  wheel.  Efficiency,  simplicity,  dura- 
bility and  continuity  of  service  are  all  of  the  greatest 
importance.  These  features  involve  not  only  the  tur- 
bine design  but  all  the  water  passages  from  the  forbay 
to  the  tail  race,  and  the  auxiliary  equipment  as  welL 
Fundamentally  the  first  cost  of  the  hydroelectric  sta- 
tion generally  exceeds  that  of  the  steam  station.  This 
has  led  to  the  use  of  the  maximum  feasible  capacities- 
and  speeds  in  the  individual  imits,  in  order  to  take  ad- 
vantage of  the  accompanying  reduction  in  cost  per  tmit 
output  of  both  the  water  wheel  and  the  generating 
equipment.  The  range  of  application  of  the  reaction 
turbine  has  also  been  extended,  thereby  increasing  its 
general  adaptability  to  meet  the  varying  condition  en- 
countered. 

It  is  gratifying  to  note  the  manner  in  which  these 
various  problems  in  design  and  application  are  being 
met  and  the  assurance  it  gives  for  our  future  progress.. 

A.    L.    SCHIEBER 


il  (ycli'aHllc  Roacrtloji  TurMiios 


U.  J    McCOKMACK 

Hydraulic  Engineer, 
Well  man-Sea  ver-Morgan  Co. 


GREATER  interest  is  being  shown  in  water  power 
development  at  present  than  at  any  time  in  the 
past.  This  is  due  largely  to  the  high  price  of 
fuel  transportation  and  labor,  the  realization  of  the 
limited  extent  of  our  fuel  reserves,  and  the  great  strides 
made  of  late  years  in  increasing  the  efilicienc)'.  of  the  de- 
velopment and  transmission  of  water  power.  It  is 
therefore  evident  that  the  method  of  applying  modern 
hydraulic  reaction  turbines  in  the  development  of  water 
powers,  and  an  outline  of  the  advances  in  hydraulic 
turbine  practice  will  be  of  great  engineering  interest. 

CLASSIFICATION    OF    REACTIOX    TURBINES 

Single  vertical  turbines,  according  to  head 

I — From  8  to  30  ft.  head  open  flume. 


111.      I       I     r  ■  i     I    ■■.  :(,K   VERTICAL  TUl;i  !  M     . 

A  10  000  hp,  32  ft.  head,  57.7  r.  p.  m.     turbine  installed  at 
the  Keokuk  Plant  of  the  Mississippi  River  Power  Company. 

2 — From  17  to  95  ft.  head concrete  spiral  casing. 

3 — From  40  to  200  ft.  head steel  plate  spiral  casing. 

4 — From  60  to  450  ft.  head cast  iron  spiral  casing. 

5 — From  300  to  800  ft.  head cast  steel  spiral  casing. 

Horizontal  turbines 

I — Single,  twin,  triplex,  quadruplex,  and  sextuplex  open 
flume,  8  to  40  ft.,  head  inside  gate  mechanism. 

2 — Twin  and  quadruplex,  end  inlet,  15  to  140  ft.  head,  steel 
plate  cylindrical  casing  being  an  extension  of  the  pen- 
stock, inside  gate  mechanism.    ■ 

3 — Twin  side  or  top  inlet,  steel  plate  cylindrical  casing,  15  to 
140  ft.  head,  inside  or  outside  gate  mechanism. 

4 — Single  cast  iron  or  cast  steel  spiral  casing,  60  to  600  ft. 
head,  quarter  turn  discharge — outside  gate  mechanism. 

5 — Twin  cast  iron  or  cast  steel  spiral  casing,  center  dis- 
charge, 60  to  200  ft.  head,  outside  gate  mechanism. 


6 — Double  discharge,  200  to  450  ft.  head,  one  cast  iron  or 

cast  steel  spiral  casing,  two  quarter  turns,  outside  gate 

mechanism. 
7- — Single  cast  iron  or  steel  plate  conical  casing,  40  to  140  ft. 

head,  inside  gate  mechanism — for  small  exciter  turbines 

— less  expensive  than  spiral  casing. 

VERTICAL  TURBINF.S 

In  the  above  classification,  multiple-runner  vertical 
turbines  have  been  omitted.  This  type  has  been  su- 
perseded by  large,  single-runner  vertical  machines  hav- 
ing high  specific  speed  runners.  They  had  the  disad- 
vantages of  a  very  inefficient  draft  tube  and  flume  ar- 
langement,  an  exceedingly  deep  flume,  all  turbine  parts 
submerged  in  the  water,  causing  much  higher  main- 
tenance charges,  and  generally  insufficient  water  seals 
over  the  top  of  runner  to  prevent  air  from  being  drawn 
into  the  wheel.  Open  flume  turbines  allow  a  very  in- 
expensive construction  of  turbine  and  flume,  which  is 


Ilil!aii|| 


FIC.    2 — THE    LARGEST    SIZE    TURBINE    EVER    BUILT 

A  10  800  hp,  30  ft.  head,  ^4-3  r.  p.  m.  turbine  for  the  Cedars 
plant  of  the  Cedars  Rapids  M  fi;.  &  Power  Co.,  Montreal, 
(  nnada. 

imperative   with   exceptionally   low   heads   in   order  to 
keep  down  the  fixed  charges. 

At  present  costs,  for  heads  over  25  ft.  and  units 
over  1500  hp,  the  additional  cost  of  a  concrete  spiral 
casing  and  outside  type  of  gate  mechanism  and  bearing 
for  a  turbine  is  justified  by  the  increase  in  efficiency,  the 
decrease  in  repairs  and  renewals  of  turbine  parts,  and 
the  greater  reliability  and  continuity  of  service.  The 
maximum  head  for  a  concrete  spiral  casing  is  about  95 
ft.  and  there  is  an  installation  of  30  000  hp  units  under 
that  head  in  course  of  construction  now.  For  heads 
over  60  ft.  there  is  a  decided  tendency  to  use  circular 
instead  of  rectangular  sections  for  concrete  spiral  cas- 
ings to  reduce  the  amount  of  reinforcing  bars. 


December,  1921 


THE  ELECTRIC  JOURNAL 


525 


Where  the  water  is  led  through  steel  penstocks  from 
a  diversion  dam  to  the  power  house,  it  is  customary  to 
use  steel-plate  spiral  casings  connected  directly  onto  the 
steel  penstocks  for  heads  as  low  as  50  ft.  However,  for 
such  a  head,  if  the  penstock  is  exceptionally  long  an  in- 
expensive construction  is  to  form  a  concrete  surge  tank 
along  the  wall  of  the  power  house  and  take  concrete 
spiral  casings  from  this.  A  wood  stave  pipe  can  then 
be  used  instead  of  steel. 


were  used  extensively,  on  account  of  the  higher  speed 
possible  with  two  or  more  small  runners  on  a  shaft. 
This  of  course  greatly  reduced  the  cost  of  the  generator. 
It  used  to  be  considered  that  horizontal  wheels  run- 
ning at  210  to  240  r.p.m.  were  the  best  drive  for  pulp 
grinders.  This  practice  is  being  supplanted  by  the  use 
of  vertical  hydro-electric  units  and  driving  the  grinders 
by  synchronous  motors.  A  greater  production  and 
better  grade  of  pulp  is  obtained  on  account  of  the  uni- 
form speed.  Such  a  system  has  the  advantages  of  a 
high-power  factor  and  a  large  amount  of  flywheel  ef- 


FIG.    3^L.\RCEST   CAPACITY    TURBINE   EVER   BUILT 

A  61  000  hp,  305  ft.  head,  187.5  r.  p.  m,  turbine  for  the 
Queenston  Plant  of  the  Hydro-Electric  Power  Commission 
of  Ontario. 

Single  vertical  turbines  are  recommended  in  this 
country  for  all  new  hydro-electric  installations.  Hori- 
zontal turbines  are  still  being  used  on  foreign  develop- 
ments, but  of  late  there  has  been  a  noticeable  conversion 
to  vertical  units  in  the  foreign  developments.  For  replac- 
ing old  horizontal  wheels  or  in  adding  units  to  old  hori- 
zontal plants,  horizontal  wheels  are  still  being 
built,  but  even  under  these  conditions  many  vertical  tur- 
bines are  being  installed.     Horizontal  wheels  are  also 


Ml..    5      SI  XII    11  l.\     lhj|;l/u.\TAL    OPEN    FLUME    TURBINE 

A  2770  hp,   17  ft.  head,  100  r.  p.  m.  unit  installed  at  the 
plant  of  the  Southern  Wisconsin  Power  Co.,  Kilbourn.  Wise. 

feet  to  take  care  of  the  other  industrial  and  lighting 
load. 

The  greatest  advantage  of  single  vertical  turbines 
over  horizontal  is  the  increased  efficiency.  From  three 
to  seven  percent  higher  efficiencies  are  being  obtained. 
This  can  be  credited  in  large  degree  to  the  absence  of 
the  bends,  such  as  occur  in  the  quarter  turn  or  double 
discharge  casing  of  a  horizontal  turbine  at  the  discharge 
of  the  runner,  where  the  velocity  is  very  high.  For 
large  capacity  units  under  a  low  head,  where  two  or 
more  draft  tubes  would  be  necessary  for  a  horizontal 
unit  with  several  runners,  there  is  a  further  loss  in  the 
draft  tubes.  Also  these  draft  tubes  are  so  long  in  the 
horizontal  direction  that  surges,  and  in  some  cases  part- 


FIG.    6 — ENli 


AblXG   TURBINE 


FIG.    4 — TWIN    HORIZONTAL  OPEN    FLUME    TURBINE 

A  3200  hp,  64  ft.  head,  257  r.  p.  m.  turbine  installed  at  the  A  5  600  hp,  72  ft.   head,  240   1-.  p.  m.  unit  installed  at  the 

plant  of  the  New  England  Power  Company,  Shelburne  Falls,  Healy  Falls  Plant  of  the  Hvdro-Electric  Power  Commission  of 

-'^lass.  Ontario. 


used  now  for  construction  jobs  or  other  temporary  pur- 
poses when  efficiency  is  not  important. 

Before  the  advent  of  the  electrical  generator,  verti- 
cal wheels  were  used  as  often  as  the  horizontal  type,  for 
driving  sawmills,  grist  mills,  and  factories  through  line 
shafting  and  gearing.  When  coupled  direct  to  gener- 
ators, horizontal  wheels  with  single  or  multiple  runners 


ing  of  the  water  column,  are  caused  and  the  turbine 
regulation  is  seriously  affected.  The  water  approaches 
a  vertical  wheel  with  a  better  flow,  devoid  of  shaqi  turns 
under  high  velocity,  such  as  is  evident  with  inost  hori- 
zontal settings.  Where  the  height  of  the  tail  water 
fluctuates  considerably,  the  vertical  arrangement  allows 
the  generator  to  be  set  well  above  the  wheel  and  tail 


526 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


water,  and  thus  precludes  any  possibility  of  flooding  the 
generator  floor.  The  design  is  simplified,  there  are  few- 
er parts  and  generally  only  one  turbine  bearing  is  re- 
quired. Where  an  outside  gate  mechanism  and  outside 
bearing  is  used  the  cost  of  renewals,  repairs  and  con- 
sequent interruptions  in  service  are  greatly  reduced. 
Due  to  the  greatly  increased  speeds  of  low-head  runners 


vent  air  being  drawn  into  the  wheel.  The  height  of 
seal  will  vary  with  the  size  of  wheel.  In  cases  of  ex- 
tremely low  head  it  has  been  necessary  to  have  a  raft 
above  the  wheels  in  order  to  prevent  vortices  forming. 


FIG.  7 — A  TWIN  TURBINE  WITH    "i 

TOP   INLET   CASING 

A  4800  hp,  100  ft.  head,  360  r.  p.  m.  unit  with  two  bronze 
runners  installed  at  the  plant  of  the  Olympic  Power  Co.  at 
Port  Angeles,  Wash. 

developed  lately,  and  the  fact  that  the  electrical  com- 
panies now  have  developed  a  full  line  of  vertical  gener- 
ators, the  first  cost  in  most  cases  is  comparable  with 
horizontal  machines. 

A  great  element  in  the  success  of  large  vertical  units 
has  been  the  development  of  the  thrust  bearing  to  a 
high  state  of  perfection.  They  have  proved  perfectly 
reliable  in  service.  The  allowable  bearing  pressures 
rnnge  from  250  to  400  lbs.  per  sq.  in.,  depending  on  the 
speed.  The  thrust  bearing  is  now  considered  a  part  of 
the  generator  and  is  furnished  by  the  generator  manu- 


FIG.    9 — AN    INSTALLATION    OF    HORIZONTAL    TURBINES 

Showing  three  6400  hp,  320  ft.  head,  514  r.  p.  m.  main 
turbines  and  two  turbine  driven  exciter  units  at  the  plant  of  the 
Portland  Railway  Light  &  Power  Co.,  Portland,  Oregon. 

If  there  are  two  or  more  concrete  draft  tubes  to  a 
unit  with  multiple  runners,  the  horizontal  length  should 
be  reduced  as  much  as  possible.  Otherwise  the  inertia 
of  the  water  in  the  long  draft  tube  becomes  so  great  that 
upon  a  sudden  closure  of  the  gates  the  water  column 
will  part,  especially  with  a  high  draft  head,  and  come 
back  with  a  bang  like  the  report  of  a  cannon,  causing 
serious  damage  to  the  turbine.  It  is  very  hard  to  regu- 
late a  turbine  under  such  conditions. 

End  inlet,  cylindrical-casing  turbines.  Fig.  7,  are 
a  less  expensive  construction  and  provide  a  better  dis- 


FIG.  8 — A  SINGLE  HORIZONTAL  SPIRAL  CASING  TURBINE 

A  6  400  hp,  320  ft.  head,  514  r.  p.  m.  turbine  installed  at 
Mt.  Hood  Plant,  Portland  Railway,  Light  &  Power  Company. 

tacturer,   being   mounted   above   the   upper   generator 
guide  bearing. 

HORIZONTAL  TURBINES 

With  open-flume  horizontal  turbines,  the  runners 
should  be  submerged  enough  below  head  water  to  pre- 


FIG.   10— TWIN  SPIR.^L  CASING  HORIZONTAL  TURBINE 

A  2300  hp,  56  ft.  head,  300  r.  p.  m,  unit  at  the  Big  Chute 
Plant  of  the  Hydro-Electric  Power  Commission  of  Ontario. 

tribution  of  water  to  the  runners  than  a  side  or  top  in- 
let, but  are  not  adapted  to  the  use  of  the  outside  t>'pe  of 
gate  mechanism.  For  heads  of  90  ft.  or  over,  the  side 
or  top  inlet  casing  with  outside  gate  mechanism  as  shown 
in  Fig.  8,  is  used,  mainly  due  to  mechanical  reasons,  i.e. 
to  withstand  the  unbalanced   forces  on  the  bulklieads 


December,  1921 


THE  ELECTRIC  JOURNAL 


527 


and  to  have  all  possible  parts  outside  of  the  water  pas- 
sages. 


1,„;     II— A   SIXGLE  VERTICAL  OPEN   FLUME  TURBINE 

A  500  hp,  25  ft.  head,  200  r.  p.  m.  unit  built  for  Osweg-o 
Falls  Pulp  &  Paper  Co.,  Fulton,  New  York. 

High-head,  single,  horizontal  turbines  in  cast-iron 
or  cast-steel  spiral  casings,  Fig.  9,  were  for  a  time  not 
favored  on  account  of  the  unbal- 
anced end  thrust  on  the  runner.  This 
was  overcome  by  proper  design  of  the 
balancing  chambers  on  the  two  sides 
of  the  runner,  balancing  pistons  or 
pipe  connections  around  the  casing 
from  the  crown  plate  to  the  draft 
tube,  and  cored  holes  through  the 
runner  hub. 

Double  discharge  turbines  allow 
higher  rotative  speeds  than  single  on 
account  of  the  smaller  diameter  of 
the  runner.  They  are  also  well  bal- 
anced for  end  thrust.  However,  they 
are  limited  where  the  band  of  the 
runner  becomes  so  large  in  respect  to 
the  entrance  diameter  of  the  runner 
that  it  is  impossible  to  work  on  the 
gate  mechanism.  This  type  of  tur- 
bine is  generally  set  with  the  shaft 
lengthwise  of  the  power  house  in 
order  that  one  draft  tube  will  not 
have  to  pass  by  the  other,  and  also  to 
eliminate  bends  in  the  feeder  pipe. 
This  of  course  requires  a  longer 
power  house. 

A     single    spiral     casing    for    a 
double    discharge    turbine    often    be- 
comes    too     big     for    large-capacity, 
medium-head    turbines.      It    is    then 
necessary   to   use   two    spiral    casings 
with  a  central  double  discharge  cas- 
ing, as  shown  in  Fig.  11.     The  units 
are  generally    placed  with  the    shaft 
crosswise  of  the  power  house  to  save 
space,   and   a   Y-pipe    distributes    the 
water  to  the  two  casings.     As  the  double  discharge  cas- 
ing is  less  efficient  than  two  quarter  turns,  one  or  two 
installations  have  been  made  with  a   single  discharge 
turbine  on  each  end  of  the  generator. 


LIMITS  OF  HEAD  FOR  REACTION  TURBINE 

The  minimum  head  for  a  commercially  successful 
hydroelectric  plant,  with  present  costs  of  materials,  lies 
between  8  and  12  feet  depending  on  the  length  of  dam 
and  the  other  considerations  entering  into  its  construc- 
tion. It  is  then  possible  only  by  using  the  highest  speed 
runners  available  with  open  flume  setting  of  turbine,  as 
shown  in  Fig.  12.  A  high  load  factor,  high  power- 
iactor,  fairly  uniform  flow,  low  cost  dam,  controlling 
works  and  power  house  are  the  requisites  of  a  success- 
ful development. 

At  the  other  extreme,  reaction  turbines  are  limited 
as  to  maximum  head  in  most  cases  by  the  speed  of  the 
generator.  There  is  a  sudden  and  decided  increase  in 
the  cost  of  the  generators  when  the  speed  exceeds  the 
limit  for  standard  construction  and  it  becomes  necessary 
to  use  the  steam  turbine  type  of  generator  with  nickel 
steel  rotor   to   withstand   the   high   centrifugal    forces. 


Specific  Spet... 


FIG.     12 — SPECIFIC    SPEED    CHART 


For  example — a  6000  kv-a  generator  at  1200  r.p.m.  will 
cost  nearly  twice  as  much  as  a  600  r.p.m.  machine  of  the 
same  capacity.  For  these  exceptionally  high  heads,  re- 
action turbines  having  specific  speeds  below  16  are  not 


528 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  li 


as  suitable  as  those  having  specific  speeds  of  around 
20  or  over.  Witli  the  lower  specific  speeds,  the  runners 
and  other  parts  offer  too  great  a  wetted  perimeter,  which 
increases  the  frictional  losses.     There  is  also  less  over- 


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13 — COMPAR.\TIVE   GUARANTEED   AND   FIELD    TEST    PERFORMANCE     CURVES 

Taken  at  45,  47  and  49  ft.  head  on  a  7  500  hp,  100  r.  p.  m. 
turbine  at  the  Junction  Development  of  the  Consumer's  Power 
Co.,  VVellston,  Mich. 


very  large  capacity  units.  The  difference  in  efficiency 
between  93  percent  for  reaction  turbines  and  85  percent 
for  impulse  turbines  is  a  very  attractive  incentive  for 
pioneering  in  the  high-head  field  for  reaction  turbines. 

TURBINE  CHARACTERISTICS 

"Specific  Speed"  is  a  term  used  to  desig- 
nate the  type  of  a  turbine  runner  or  wheel. 
It  is  the  speed  at  which  the  wheel  would  run 
if  it  were  reduced  in  size,  without  changing 
the  design,  so  as  to  develop  one  horse-power 
under  one  foot  head. 

Or,  Specijic  Speed.  .\\  =  ^^  *"•  ^  ^    ^f- 

HxyTT 

A  convenient  graphical  method  of  deducing 
the  specific  speed  without  using  this  formula  is  afforded 
by  Fig.  12. 

Specific  speed  is  a  complete  measure  of  the  possible 
performance  of  a  runner  under  any  head,  both   as  to 


pressure  at  the  entrance  to  the  runner  and  a  greater  cur- 
vature in  the  vanes  which  increases  the  tendency  to  cor- 
rode. 

Further,  a  limit  is  reached  where  the  velocity  head 
at  the  top  of  the  draft  tube  (^)  approaches  the  head  l^wer  and  speed.  It  is  not  a  measure  of  its  efificiency 
due  to  barometric  pressure.  The  allowable  draft  head 
is  then  correspondingly  reduced.  In  one  case  where 
1000  ft.  head  was  considered,  the  velocity  at  the  top  of 
the  draft  tube  of  50  ft.  per  sec.  would  require  the  run- 
ner to  be  submerged  below  tail  water  in  order  to  main- 
tain the  water  column  in  the  draft  tube,  and  to  take  ad- 
vantage of  the  full  head.  In  several  installations  where 
the  velocity  head  at  the  top  of  the  draft  tube  added 
to  the  draft  head  approaches  the  head  due  to  barometric 
pressure,  a  crackling  noise  is  set  up  in  the  draft  tube. 
Upon  sudden  load  changes  of  any  magnitude,  the  water 
column  parts  and  comes  back  with  such  tremendous 
force  that  it  shakes  the  entire  power  house.  This  con- 
dition is,  of  course,  destructive  to  the  turbine  parts,  par- 


FIG.    IS— TURBINE   READY  TO  TEST  IN    HOLYOKE  WATER   POWER   COM- 
PANY'S     TESTING     FLUME 

but,  aside  from  that  consideration,  it  is  an  absolute  type 
characteristic  and,  given  the  specific  speed  of  a  runner, 
it  is  possible  to  decide  at  once  whether  it  is  suitable  for 
a  given  set  of  conditions. 

European  practice  is  to  use  exceedingly  high  speci- 
fic speeds,  even  for  medium  and  high  heads,  in  order  to 
reduce  the  cost  of  the  generator,  regardless  of  other 
considerations.  It  has  been  the  experience  in  this  coun- 
try' that  if  too  high  specific  speeds  are  used,  particularly 
for  medium  and  high  heads,  the  runners  are  liable  to 
show  corrosion  or  pitting,  due  mostly  to  the  excessively 
high  velocities  through  the  runner.  A  limiting  value  of 
specific  speed  for  any  given  head  as  determined  by  ex- 
5050 


no,      14 — HOLVOKE     TESTI.NG      FLUME 

ticularly  the  runners,  quarter  turns  and  metal  draft 
tubes.  It  also  increases  the  pitting  action  and  may  be 
relieved  to  a  great  extent  by  admitting  air  into  the  draft 
tube. 

The  highest  head  yet  attempted  for  a  reaction  tur- 
bine is  800  ft.     This  may  be  exceeded  in  the  future  with 


perience  is:  X, 


-  +  19. 


H  +  3^ 

For  high  heads  a  low  specific  speed  runner  is  used. 
This  type  of  runner  gives  a  flat  efficiency  curve  over  a 
wide  range  of  power  and  also  over  a  wide  range  of  speed 
or  head.  High  part  gate,  and  full  gate  efficiencies  are 
obtained,  and  the  maximum  efficiency  occurs  at  about  75 


December,  1921 


THE  ELECTRIC  JOURNAL 


529 


to  85  percent  of  full  load.  A  low  head  runner  of  high 
specific  speed  gives  a  more  peaked  curve  over  the  power 
range  and  for  a  variation  of  speed  or  head.  The  part 
•gate  efficiencies  are  lower,  and  the  maximum  efficiency 
occurs  at  90  to  93  percent  of  full  load. 


may  show  a  difference  of  three  to  four  percent  in  effi- 
ciency unless  the  speed  is  set  to  suit  the  characteristics 
of  the  wheel.  This  is  particularly  important  for  a  vari- 
able head  plant. 

Tests  made  on  25  to  30  inch  model  runners  at  the 


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FIG.    16 — CO>irAR.\TIVE  CU.^RANTEKn,    HOLYOKE  AND  FIELD  TEST,  PERFORMANCE   CURVES 

For  22000  hp,  515  ft.  head,  42S  r.  p.  m.  single  vertical  turbines. 


When  the  turbine  is  used  to  drive  a  generator  it 
has  to  run  at  a  constant  speed,  but  if  the  head  varies 
from  normal,  the  efficiencies  will  be  affected  the  same 
as  if  the  head  were  maintained  constant  and  the  speed 
varied,  as  shown  in  Fig.  13. 

On  large  units,  it  is  sometimes  desirable  to  block 
the  gate  stroke  at  the  gate  opening  corresponding  to 
maximum  efficiency,  and  not  allow  the  turbine  to  pull 
a  greater  load.  The  governor  can  regulate  the  gates  up 
to  this  opening  and  the  units  are  operated  at  this  point 
of  maximum  efficiency  as  much  as  possible.  This  is 
called  "running  against  the  block"  and  is 
very  good  practice  where  steam  aux- 
iliaries or  low  head  regulating  plants  are 
connected  to  the  system  and  can  take  the 
fluctuation  of  loads. 

The  number  of  units  to  be  installed  in 
a  plant  is  dependent  to  a  great  extent 
upon  the  variation  in  stream  flow  through- 
out the  year  and  upon  the  part  gate  effi- 
ciencies of  the  turbines.  In  order  to 
maintain  a  high  average  operating  effi- 
ciency of  the  plant  with  a  wide  variation 
of  loads,  it  is  necessary  to  use  a  larger 
number  of  units  for  a  low  head  plant  than 
for  a  high  head  plant  of  the  same  capacity. 
A  high  head  development  generally  has 
a  more  uniform  flow  and  the  part  gate  effi- 
ciencies of  the  turbines  are  higher. 

The  speed  of  the  unit  should  be  left 
to  the  turbine  manufacturers.     A  genera-     •'■■"     ^ 
tor    can    be    built    for    any    synchronous      ™-  i7— plan 
^peed    within    a    wide    range    and    give    within    one 
percent  of  the  same  efficiency  for  the  same  capacity. 
However,  a  turbine  is  much  more  sensitive  to  speed  and 


Holyoke  testing  flume  form  the  only  direct  comparative 
results  of  the  various  manufacturer's  designs  of  runners, 
as  this  is  the  only  official  testing  flume  in  the  United 
States.  All  tests  are  made  there  under  the  same  condi- 
tions of  apparatus,  methods  and  men.  The  results  of 
the  Holyoke  tests  are  applicable  to  the  prediction  of  the 
performance  of  a  larger  turbine  under  a  different  head. 
The  speed  will  vary  inversely  as  the  diameter  of  the 
runners  and  directly  as  the  square  root  of  the  head.' 
The  horse-power  will  vary  as  the  diameters  squared 
and    as    the    three-halves    power    of    the    head.     The 


VIEW  OF  A  4250  HP.,  32  FT.   HEAD,  100  E.   P.   M.  VERTICAL     THKUINE 

quantity   of   water  flowing  will   vary   as   the   diameter 
squared  and  as  the  square  root  of  the  head. 
(To  he  continued) 


Circle 


'^r 
o)^ 


irnE8n\mjo:n 


tDms 


R.  D.  EVANS  and  H.  K.  SELS 

General  Engineering  Dept., 


NO  method  for  the  complete  graphical  solution  of 
power  transmission  problems  has  been  de- 
veloped up  to  the  present  time,  which  in  itself 
covers  all  sets  of  conditions  with  any  degree  of  ac- 
curacy. The  possible  combinations  of  networks  for 
this  type  of  problem  are  quite  varied,  and  it  has  been 
shown  by  the  authors*  that  any  of  these  combinations 
can  be  replaced  by  an  equivalent  network  represented 
by  a  single  set  of  general  circuit  constants,  which  can 
be  applied  in  the  usual  manner.  This  article  is,  there- 
fore, limited  to  the  development  of  a  graphical  method 
for  the  complete  solution  of  transmission  problems  in 
their  many  and  varied  forms. 

The  primary  object  of  an  approximate  graphical 
solution  is  not  one  of  accuracy,  although  this  should 
be  within  a  few  percent  of  that  obtained  by  an  exact 
method  of  calculation  but  one  that  gives,  in  as  simple 
and  general  way  as  possible,  a  maximum  set  of  solu- 
tions with  a  minimum  of  calculation.  When  such  a 
diagram  has  been  finished,  the  most  desirable  condi- 
tions of  operation  can  be  readily  selected,  and  the 
rigid  mathematical  solution  may  be  applied  to  the  par- 
ticular case  with  any  further  degree  of  accuracy  that 
may  be  desired.  Usually  this  is  unnecessary  for  the 
majority  of  problems,  as  a  good  graphical  method  is 
limited  in  accuracy  only  in  the  drawing  and  reading  of 
the  scalar  quantities. 

DWIGHT   CIRCLE  DIAGRAM 

The  circle  diagram,  as  developed  by  Mr.  H.  B. 
Dwight*  and  as  quite  generally  used,  gives  the  condi- 
tions of  load  necessary  at  the  receiver  end  of  the  line 
to  obtain  a  certain  voltage  regulation.  In  a  recent 
article,  it  was  shown  by  the  writers  that  the  general 
circuit  constants  can  be  developed  so  as  to  include  all 
portions  of  a  transmission  system  from  the  low-tension 
bus  of  the  generator  to  that  of  the  receiver.  In  any 
case,  these  constants  reduce  to  the  familiar  form  of  the 
hyperbolic  or  convergent  series  method : 

E,  =  A„  E,  +  h\Ir (/) 

I,   =    Co    Er  +  D„/r {.-) 

E,  =  Do  E,-Boh (J) 

I, Co  Es  ^Aoh M 

Where,  A^  is  equal  to  D^  for  the  symmetrical  line,  i.e., 
the  case  of  the  transmission  line  alone,  or  where 
similar  supply  and  receiver  transformers  are  in- 
cluded. The  constants  A^,  B^,  Co  and  D^  have  par- 
ticular values,  dependent  upon  the  transmission  line 
conductors  and  their  spacing,  equivalent  transformer 
impedances,    and    the    operating    conditions    assumed. 

♦"Transmission  Lines  and  Transformers",  in  the  Journal 
for  Aug.  1921,  p.  356. 

*See  article  on  "The  Calculation  of  Constant  Voltage 
Transmission  Lines"  by  H.  B.  Dwight  in  the  Journ.vl  for  Sept. 
19 14,  p.  487. 


Westinghouse    Electric   &   Mfg.    Company 

Table  III*  is  very  useful  in  determining  these   con- 
stants for  various  conditions. 

The  development  of  the  circle  diagram  from  equa- 
tion (i)  shows  that  for  given  generator  and  receiver 
voltages  there  are  particular  circles  whose  ordinates 
represent  the  total  reactive  power  and  whose  abscissae 
represent  the  total  real  power  at  the  receiver,  the  par- 
ticular values  of  which  are  fixed  according  to  the  volt- 
ages assumed.  Similarly,  from  equation  (3),  it  may  be 
shown  that  the  generator  conditions  are  determined  by 
a  circle  based  upon  the  assumed  voltages.  The  con- 
stants of  these  particular  circles  may  be  expressed  con- 
ventionally as  follows : 

jJ_E£- 
1000 


An  = 


Bk  = 


Cu  = 


A^=- 


r  e;^ 


B»  = 


Cs  = 


1000 
SjtTE^ 

JOOO 

3nE,Er 
1000 


■(9) 
(/o) 


where  the  nomenclature  is  fully  explained  in  the  ap- 
pendix. 

This  completes  the  diagram  up  to  the  point  where 
the  generator  and  receiver  conditions  can  be  deter- 
mined for  any  given  voltages.  That  is,  for  any  given 
power  load,  Kv-aR  and  Kv-as  can  be  determined  from 
the  ordinates  at  the  intersection  of  the  power  abscissa 
corresponding  to  that  load  and  the  receiver  and  supply 
circles  respectively,  as  shown  in  Fig.  I*.  Any  point  not 
on  the  circle  represents  a  different  voltage  condition 
than  that  assumed.  Hence  when  a  vector  representing 
a  given  kv-a  load  at  a  given  pov\-er-factor,  such  as  that 
.shown  in  Fig.  i,  does  not  end  on  the  receiver  circle,  a 
synchronous  condenser  is  required  in  order  to  main- 
tain the  assumed  voltage  conditions.  The  condenser 
capacity  required  is  represented  by  the  vertical  line 
dropped  from  the  load  vector  to  the  receiver  circle. 
Thus  in  Fig.  i,  the  shaded  area  represents  the  syn- 
chronous condenser  capacity  required  to  maintain  the 
receiver  voltage  constant  and  equal  to  a  constant  sup- 
ply voltage  at  the  assumed  values,  at  all  loads  from 
zero  to  full  load,  as  identified  by  lag  and  lead.  The 
vector  shown  for  Kv-as  neglects  the  transmission  loss- 
es and  represents  100  percent  efficiency. 

It  will  be  seen  from  the  diagram  that  all  phase  re- 
lations can  be  very  easily  determined  directly  for  all 
loads,  and  by  plotting  other  circles  for  different  volt- 
age conditions,  for  practically  any  regulation.  Since 
/,  m,  I',  m',  and  n  depend  entirely  upon  the  general  cir- 


*In  the  Journal  for  Aug.  1921,  p.  358. 

*Some  prefer  to  plot  the  circle  diagrams  so  that  posi- 
tive Q  refers  to  leading  Kv-a.  However,  when  inductive  re- 
actance is  taken  a%  -{■  j  x  and  capacitance  as  -f  ;  B,  this  is  not 
mathematically  consistent.  For  this  reason,  minus  Q  refers 
to  leading  Kv-a  in  this  article,  and  in  order  to  plot  the  dia- 
gram the  other  way  the  formulas  or  diagrams  given  must 
be  reversed  in  sign  as  far  as  Q  is  concerned. 


Vol.  XVIII,  No.  12 


THE   ELECTRIC  JOURNAL 


531 


cuit  constants  of  the  system,  which  are  constant  for  a 
given  network  and  voltage  class,  the  circle  diagram 
constants  can  be  calculated  very  simply  for  a  variety  of 
voltage  combinations  at  the  supply  and  receiver  ends. 
This  is  quite  useful  in  representing  the  conditions  ob- 
tained by  utilizing  compensated  voltage  regulation  at 
the  generator,  a  falling  receiver  voltage  characteristic, 
or  constant  voltage  transmission  at  either  end  or  at 
both  ends  by  the  use  of  synchronous  condensers  at  the 
receiver. 


and  (7).  For  a  given  load  and  power-factor  at  the 
receiver,  the  generator  conditions  at  100  percent  effi- 
ciency will  be  given  by  the  intersection  of  a  perpen- 
dicular to  the  P  axis  with  the  supply  circle  having  the 
same  regulation  as  determined  by  the  receiver  circle. 
The  receiver  voltage 
for  any  load  at  any 
power-factor,  in  per- 
cent of  Sr  can  be 
readily     determined    by 


+Q 

L 

I     A 
-P                   K 

^'''^^^r^''?^»,''\r 

0    c/ 

^^^L-li^:^.^;;^ 

1        '^ 

100?..  Es  .    Er 

Er  -  Constant  Voltage 

FIG.     I — METHOD    OF    DETERMINING 

THE     SYNCHRONOUS     CONDENSER 

CAPACITY 

To  obtain  the  voltage  regula- 
tion desired  for  any  load  at  a 
given  power-factor. 


FIG.    2 — VARIATION     IN    RECEIVER 
VOLTAGE 

For  constant  supply  voltage 
with  constant  load  at  variable 
power-factors. 


FIG.    3 — THE    EFFECTS    OF    VOLTAGE 
CO.MPENSATION 

At    the    supply    end    for  a 
given  load  and  power-factor. 


The  diagram  shown  in  Fig.  2  is  representative  of 
the  conditions  obtained  when  the  generator  voltage  is 
held  constant  and  the  receiver  voltage  is  free  or  un- 
regulated and  takes  a  value  determined  by  the  constants 
of  the  circuit  and  the  load  conditions  on  the  receiver. 
With  constant  generator  voltage,  the  center  of  the 
supply  circle  is  constant,  as  located  by  equations  (8) 
and  (9)  but  the  radius  varies  with  the  receiver  volt- 
age (10).  The  center  and  radius  of  the  receiver 
circles    vary   in   accordance    with    equations    (5),    (6) 


interpolation  on  such  a  chart.  This,  gives,  perhaps,  one 
of  the  plainest  graphical  representations  of  the  effects 
of  variation  in  load  and  power-factor  upon  the  regu- 
lation, and  the  load  and  power-factor  conditions  ob- 
tained at  the  generator. 

Conversely  to  the  above,  the  diagram  shown  in 
Fig.  3  is  representative  of  the  conditions  obtained  when 
the  receiver  voltage  is  considered  constant  and  the 
generator  voltage  variable,  a  condition  such  as  would 
be  obtainable  by  the  use  of  a  compensated  voltage  regu- 


532 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


lator.  It  is  shown  in  the  diagram,  with  the  load  as- 
sumed, that  16.5  percent  voltage  compensation,  based 
upon  the  minimum  generator  voltage,  is  the  maximum 
necessary  to  maintain  constant  receiver  voltage  with- 
out using  a  synchronous  condenser.  That  is,  at 
no  load,  the  receiver  circle  must  be  drawn  through  the 
zero  load  point,  corresponding  to  a  voltage  of  96  per- 
cent Es,  as  shown  by  the  dotted  line,  and  at  full  load 
the   receiver  circle   must  be   drawn   through   the   full 

TABLE  I— EFFECT  OF  VOLTAGE  COMPENSATION 


Percent 
Generator     Voltage 

Percent 
Compensation 

Percent  Maximum 
Condenser  Capacity 

No  Load 

Full  Load 

Lag 

Lead 

96 
98 
100 

\12 
107 
ICO 

16.5 
9 
0 

0 
15 
30 

0 
40 
100 

load  point,  corresponding  to  112  percent  £s-  In  prac- 
tice it  is  not  necessary  to  draw  the  circles  which  are 
shown  dotted,  as  these  points  can  readily  be  inter- 
polated. 

With  only  nine  percent  voltage  compensation, 
such  as  between  98  and  107  percent  voltage,  the 
synchronous  condenser  required  will  be  as  designated 
by  the  cross-hatched  area.  Intermediate  points  on  the 
curve  KD  are  obtained  by  assuming  straight  line  com- 
pensation as  illustrated  in  Fig.  4  for  five  percent. 
Then  the  point  on  this  curve  for  any  load  is  at  the  inter- 
section of  the  ordinate  for  that  load  with  the  receiver 
circle  correspondmg  to  the  voltage  on  the  compensa- 
tion curve  at  that  load.  These  conditions  show  that  only 
60  percent  of  the  load  could  be  carried  with  nine  per- 
cent compensation  without  a  synchronous  condenser,  as 
represented  by  the  intersection  of  the  105  percent 
(96  -\-  9)  receiver  circle  with  the  load  line.  In  order 
to  carry  this  same  load  with  zero  voltage  compensation 
at  the  generator,  it  would  be  necessary  to  increase  the 
condenser  capacity  to  2.5  times  that  with  nine  percent 
compensation,  as  represented  by  the  dotted  line  at  full 
load,  and  throughout  the  range  of  load  as  bounded  by 
the  section  of  the  100  per- 
cent circle  AB  and  the  90 
percent  power- factor  load 
line.  A  summary  of  the 
diagram  for  the  same 
loads  is  shown  in  Table  I, 
in  which  the  maximum 
condenser  capacity  re- 
quired with  zero  compen- 
sation is  assumed  as  100 
percent. 
The  conditions  at  the  supply  end  in  Fig.  3  are  re- 
presented by  the  line  CD  for  a  90  percent  power-factor 
load  with  16.5  percent  compensation  and  no  synchron- 
ous condenser,  any  point  on  this  curve  being  at  the 
intersection  of  the  load  ordinate  with  the  supply  circle 
for  the  voltage  corresponding  to  that  load.  With  nine 
percent  compensation  and  40  percent  synchronous  con- 


no.    4 — STRAIGHT    UNE   VOLT- 
AGE   REGULATION 

At    both    supply    and    re- 
ceiver ends. 


denser,  the  line  EF  represents  the  supply  kv-a  for 
different  loads.  For  zero  compensation  and  with  re- 
ceiver conditions  defined  by  line  AB,  the  corresponding 
supply  conditions  are  defined  by  line  GH. 

By  combining  the  two  conditions  shown  in  Fig.  2 
and  Fig.  3,  that  is,  using  compensated  voltage  regula- 
tion at  the  generator  and  allowing  the  receiver  voltage 
to  fall  off  according  to  the  curves  in  Fig.  4,  conditions 
will  be  obtained  as  shown  in  Fig.  5.  Here  it  is  again. 
shown  that  the  synchronous  condenser  capacity  has 
been  materially  reduced  over  that  which  would  be  re- 
quired with  equal  and  con- 
stant supply  and  receiver 
voltages.  In  fact  in  this 
particular  case,  the  condi- 
tions are  very  similar  to  the 
conditions  in  Fig.  3,  using 
nine  percent  compensation 
with  40  percent  synchron- 
ous condenser. 

The      three       diagrams 
Figs.  2,  3  and  5,  are  com- 
parative as  they  were  taken 
from      an     actual 
v"'*  problem  of  a  giv- 

en   load    and   giv- 
en       transmission 
+p      system      and     the 
100    percent 
circles      are      the 
same      in     e  a  c  h. 
While  the  particular  percentages  given 
are    not    general,    they    serve    to    show 
what  can  be  done  with  this  method  of 
calculation  in  determining  the  best  op- 
erating conditions. 

Thus  far,  the  solution  of  a  given 
problem  by  the  methods  indicated  is 
fairly  complete,  with  the  exception  of 
the  determination  of  the  line  loss  and 
the  transmission  efficiency.  In  the 
diagrams  given  above,  100  percent  effi- 
ciency has  been  assumed  to  determine 
the  load  conditions  at  the  generator 
with  a  given  load  at  the  receiver,  but 
there  is  an  exact  method  which  may  be 
used  to  correct  for  this. 

LOSS    EQUATIONS 

The  line  loss  is  usually  determined 
from  either  the  i?/^  loss  or  the 
the  generator  and  receiver  loads, 
former  method  is  in  error,  due  to 
the  effects  of  the  line  charging  current  upon  the 
load  current.  The  latter  method  is  usually  approxi- 
mate as  far  as  calculations  go,  unless  these  are  carried 
out  on  a  calculating  machine,  as  this  method  involves 
the  small  difference  of  two  large  quantities.  It  is 
possible  to  express  the  generator  and   receiver  power 


FIG.     5 —    LOAD 
CONDITIONS 

Obtained  at 
the  supply  end 
with  voltage 
conditions  at 
both  ends  as 
shown  in  Fig. 
4- 

difference     of 
However,    the 


December,  192 1 


THE  ELECTRIC  JOURNAL 


533 


in  general  terms  and  show  that  the  difference  of  the 
power  components  gives  the  total  line  or  transmission 
loss.     This  may  be  expressed  as: 

Total  loss  =  IPr  +  uEk'  +  jz'/r-  +  zvQn (//) 

where  t,  u,  v  and  w  are  constants,  dependent  upon  the 
general  circuit  constants,  as  explained  in  the  appendix. 

The  terms  in  the  above  expression  may  be  identi- 
fied in  the  following  manner:  The  second  term  re- 
presents the  no-load  loss  of  the  system.  The  third 
term  gives  the  equivalent  Rl'^  loss  due  to  the  load  cur- 
rent alone.  Since  the  charging  current  and  load  cur- 
rent flow  through  the  same  conductor,  the  total  loss 
involves  more  than  the  Rl^  loss  of  the  individual  cur- 
rents as  given  by  the  second  and  third  terms.  This 
additional  loss  will  vary  with  the  relative  phase  rela- 
tions of  the  two  currents  and  is  provided  for  by  the 
first  and  fourth  terms. 

The  total  loss  that  is  chargeable  to  transmission 
is  made  up  of  three  parts,  namely,  transformer,  trans- 
mission line,  and  synchronous  condenser.  If  the 
general  circuit  constants  have  been  applied,  all  or  a 
part  of  the  transformer  losses  and  the  transmission 
line  losses  will  be  given  by  equation  (11)  and  to  this 
can   be   added   the   other   losses    for   determining   the 


PIG,    6 — METHOD   OF    DETERMINIXG    SUPPLY    LOAD   CONDITIONS 

With     given     receiver    conditions,     including   transmission 
losses. 

transmission  efficiency.  However,  this  may  not  be  the 
most  convenient  or  easiest  way  to  make  the  calcula- 
tions, as  the  segregated  losses  of  the  transformers  may 
not  be  at  hand  if  they  have  not  all  been  included  in  the 
general  circuit  constants.  If  this  is  the  case,  the  trans- 
mission line  loss  may  be  calculated  alone  for  the  dif- 
ferent loads  and  the  efficiency  curves  of  the  trans- 
formers and  condensers  may  be  used  to  plot  the  re- 
sultant efficiency  curve. 

LOSS  ON   THE   CIRCLE  DIAGRAM 

Having  provided  a  means  for  accurately  deter- 
mining the  transmission  losses,  these  may  be  added  to 
the  receiver  load  for  determining  the  conditions  of  load 
at  the  supply  end,  as  shown  in  Fig.  6.  It  must  be  kept 
in  mind  that  only  those  losses  as  given  by  equation 
(11),  using  the  same  general  circuit  constants  used  in 
equations  (5)  to  (10)  for  determining  the  circle  dia- 
gram, should  be  so  added  in  order  to  determine  the 
generator  conditions.  The  line  RS  shows  the  phase 
shift  of  the  load  or  change  of  power-factor  along  the 
line  from  receiver  to  generator.  This  phase  shift  will 
be  proportional  to  the  distance  along  the  transmission 
line  except  for  the  sudden  phase  shift  of  the  trans- 
formers at  the  ends  if  they  have  been  included. 


LOSS   CIRCLE  DIAGRAM 

The  loss  formula,  (n),  may  be  put  in  the  form 
of  a  circle  and  plotted  in  connection  with  the  regular 
circle  diagram*.  This  it  seems  desirable  to  do,  as  the 
losses  neglected  when  using  the  general  circuit  con- 
stants are  practically  constant  for  different  loads,  so 
that  the  most  economical  point  of  operating  the  line 
can  be  determined  from  the  diagram.  The  centers  and 
radii  of  the  loss  circles  will  be  given  by : 
t 


Pr  = 


Or 


-Ek' 


Er' 


Radius  =  Er  \l—+  (<-  +  a'-  —  4"  ^)  ~7gr 

where  the  derivation  and  nomenclature  is  fully  ex- 
plained in  the  appendix.  It  is  to  be  noted  that  the  posi- 
tion of  the  loss  circles  varies  for  changes  in  the  re- 
ceiver voltage  and  that  this  must  be  taken  into  account 
for  different  assumptions  in  regulation. 

EFFICIENCY  CIRCLE  DIAGRAM 

The  transmission  efficiency  -^  can  be  expressed  as 
the  ratio  of  the  receiver  power  to  the  receiver  power 
plus  the  losses,  and  may  similarly  be  expressed  in  the 
form  of  a  circle  which  can  be  plotted  on  the  regular 
circle  diagram.  The  center  and  radius  of  the  effi- 
ciency circles  will  be  given  by : 

■^R"  r      / 100       W 

w 


Radius  =  jyyj  ['-{^Y  -')]  +  ""'  "  ^  "'' 
where  the  derivation  and  nome  nclature  is  fully  ex- 
plained in  the  appendix.  It  is  to  be  noted  that  the 
ordinate  Qr  for  the  position  of  the  centers  of  the 
circles  is  the  same  for  both  efficiency  and  loss  circles, 
and  may  be  called  the  line  of  minimum  loss.  Also  the 
variation  of  the  receiver  voltage  effects  the  position  of 
the  circles  as  before,  except  that  the  radius  is  effected 
as  the  square  of  the  voltage. 

NEGATIVE    POWER 

An  analysis  of  the  voltage-power  expression  shows 
that  the  load  conditions  for  a  negative  load  at  the  re- 
ceiver or  supply  are  the  same  as  for  a  positive  load  at 
the  supply  or  receiver  with  the  same  voltages  as  the 
points  where  the  power  is  supplied  or  received.  This 
means  that  the  same  circle  diagram  for  receiver  or  sup- 
ply can  be  used  for  positive  and  negative  power  with 
the  voltages  fixed  at  the  ends  regardless  of  the  flow  of 
power.  The  same  is  true  of  the  loss  circles,  of  which 
there  are  two  sets,  one  for  the  supply  and  one  for  the 
receiver  end. 

An  analysis  of  the  efficiency  expressions  shows 
that  there  are  four  sets  of  circles,  two  for  the  supply 
end  and  two  for  the  receiver  end  for  positive  and  ne- 


*In   a   manner   suggested   by    Monsieur    G.    Darieus,    Con- 
sulting Engineer. 


534 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


gative  power  respectively.  The  two  expressions  for 
positive  power  at  the  supply  and  receiver  ends  are 
given  in  the  appendix  by  equations  (14)  and  (15). 
The  other  two  expressions  for  negative  power  are  the 
same,  except  that  with  negative  power  the  term  for 

percent  loss  is  negative,  that  is  the  terms  (   '— —  /  J  for 

the  receiver  end  will  now  be  f  / '—    J,  andl/-.^  I 

for  the  supply  end  will  be  (.]?_) 
\ioo      f 


COMPLETE  CIRCLE  DIAGRAM 


The  circle  diagram  as  now  modified  may  or  may 
not  include  transformers  and  will  appear  as  shown  in 


Minimum  Lo^» 


FIG.    7 — COMPLETE    CIRCLE    DIAGRAMS 

Showing  loss  and  efficiency  circles  for  a  constant  receiver 
voltage. 

Fig.  7,  from  which  the  loss  and  efficiency  can  be  ob- 
tained directly,  interpolating  where  necessary.  For 
example,  a  load  of  such  magnitude  and  power-factor 
that  it  would  be  represented  by  the  point  at  the  inter- 
section of  the  2000  kw  loss  and  95  percent  efficiency 
circles,  would  have  a  loss  of  2000  kw  and  an  efficiency 
of  95  percent.  In  the  example  given  a  load  of  50000 
Kw,  with  97  percent  leading  power-factor  to  maintain 
constant  receiver  voltage,  can  be  transmitted  with  an 


efficiency  of  94.5  percent  having  3000  Kw  loss  as  read 
from  the  curves.  This  shows  how  closely  these  values 
may  be  interpolated. 

In  order  to  simplify  the  computations,  the  loss  and 
efficiency  circles  need  only  be  calculated  for  the  voltage 
regulation  giving  a  condenser  of  normal  design  and 
minimum  size,  or  for  voltage  conditions  fixed  by  some 
other  factor  of  operation.  Since  tlie  loss  and  efficiency 
circles  may  be  developed  in  terms  of  either  generator . 
or  receiver  quantities,  as  shown  in  the  appendix,  they 
may  be  computed  for  whichever  end  the  voltage  con- 
ditions are  considered  constant,  and  in  this  way  the 
effects  of  different  voltage  regulations  will  be  reduced. 

The  point  of  disappearance  of  the  efficiency  circles 
on  the  diagram  is  the  point  where  the  radius  becomes 
equal  to  zero  and  is  the  point  of  maximum  efficiency 
of  the  line.     This  may  be  expressed  as  follows: 
E^^    \ 

2V     \ 


/'r  = 


(?K  =    -  —   ^•r' 

The  derivation  is  fully  explained  in  the  appendix. 

The  efficiency  circles  bring  out  very  clearly  in  the 
diagram,  without  further  derivation  of  any  formula, 
that,  in  general,  a  transmission  system  is  the  most  effi- 
cient when  operating  at  a  lagging  power-factor.  The 
efficiency  increases  very  rapidly  at  first  with  small  low 
power-factor  loads,  then  reaches  a  maximum  and  falls 
off  gradually  to  full  load,  which  is  probably  at  leading 
power-factor  in  order  to  maintain  the  regulation. 
Similarly,  for  a  constant  impedance  load,  the  varia- 
tion of  efficiency  witli  power-factor  is  rapid  at  first, 
increasing  with  low  lagging  power-factors,  reaching  a 
maximum  before  reaching  unity  power-factor  and 
gradually  decreasing  at  an  ever  increasing  rate  as  the 
power-factor  decreases  leading. 

For  a  transmission  system  to  operate  at  the  most 
efficient  point  throughout  the  range  of  load  with  con- 
stant receiver  voltage,  it  is  necessary  to  operate  with 
compensated  voltage  regulation  at  the  generator  in  such 
a  way  that  the  receiver  load  conditions  will  coincide 
with  the  line  of  minimum  loss.  With  constant  genera- 
tor voltage,  the  receiver  voltage  should  be  decrea'sed  at 
light  loads  and  increased  at  heavy  loads.  In  either 
case,  the  generator  voltage  will  be  approximately  equal 
to  the  receiver  voltage  at  no  load. 

CONCLUSIONS 

The  diagram,  as  modified,  shows,  as  completely  as 
possible  by  any  known  method,  all  the  solutions  of 
generator  and  receiver  conditions,  losses  and  efficiency, 
with  or  without  transformers,  to  a  degree  of  accuracy 
approached  only  by  complete  numerical  solutions. 
While  at  first  the  computations  may  appear  compli- 
cated, fully  half  of  them  are  simple  arithmetic  calcula- 
tions which  are  relatively  simple  in  comparison  to  the 
manipulation  of  the  complex  quantities  which  must  be 
used  in  solving  for  the  general  circuit  constant  or  mak- 
ing a  similar  mathematical  solution. 


December,  1921 


THE  ELECTRIC  JOURNAL 


535 


The  basis  of  the  graphical  method  which  has  been 
covered  by  this  article  is  exact,  and  the  only  errors  in- 
volved are  those  of  calculation  or  certain  approxima- 
tions which  have  previously  been  pointed  out  in  obtain- 
ing the  necessary  constants,  and  the  laying  out  and 
reading  of  the  scalar  quantities.  This  method  gives 
a  multiplicity  of  answers  for  arriving  at  a  concrete  con- 
clusion, whereas  the  same  amount  of  work  through  a 
mathematical  method  would  accomplish  the  solution 
of  only  one  particular  set  of  conditions.  A  further  ad- 
vantage of  this  method  is  that  it  points  out  the  best 
conditions  of  operation  in  regard  to  voltage  in  order 
to  obtain  the  maximum  efficiency  and  the  most  econo- 
mical balance  of  efficiency. 

APPENDIX 

In  Table  III,  p.  358  of  the  J&urnal  for  August  1921, 
formulas  are  given  for  determining  the  general  circuit  con- 
stants. Ad,  Bo,  Co  and  Do  for  practically  every  circuit  con- 
dition. By  similar  methods  of  solution,  constants  for  any  type 
of  network  can  be  obtained.  These  constants  have  been  defined 
in  this  article  by  equations  (i)  to  (4)  and  for  simplification  in 
the  following  equations  can  be  expressed  as  follows ; — 

Ao  =  <7i  +  ja-: 

Bo  =  y?o  +jXu 

Co  =  go  +  jbo 

£>o  =  d,+  jdi 

CIRCLE  DIAGRAM* 

From  equation  (i)  can  be  derived  the  usual  circle  dia- 
gram in  terms  of  the  load  conditions  at  the  receiver  as  fol- 
lows : — 

E,  E,  =    (./„  E,  +  i^o  It)    (.7o  Er  +' A  Z) 

This  expression,  when  expanded  and  simplified,  gives  the 
equation  of  a  circle: — 

(Pk  +  Any-+  (Qn  +  Buy-  =  Cr2 
Where : — 


^^^/A.B.  +  AoBo\^,^Ja,Ro+_^\ 
\       2Boho      )  \  yr,r-f  AV-  / 

(AuBo-AoBa\  /ai-Vi.  -  trgA'A 

^BoBo         )  \    A-n-'-l-A,,-    ) 


Er-  =IEh^ 


Cii  = 


EsEr 
BoBo 


Es  En 


>iEs  En 


V/ZAr'  -I-  Ao^ 

When  Pjt  and  Qb  are  expressed  in  Kv-a,  the  constants 
A,Ti  Be  and  Cr  must  be  divided  by  i  000  according  to  equations 
(5)  to  .(7). 

Similarly,  equation  (3)  can  be  expanded  into  a  ■  circle 
diagram  in  terms  of  the  load  conditions  at  the  supply  end,  as 
follows : — 

Er  E\  =  {Do  E,  -  Bo  Is)      (/7„  F,  -  Bo  7s) 

This  expression  when  expanded  and  simplified  gives  the 
equation  of  a  circle: — 

{Ps-  As)--^  {Qs  -  B^y-=  Ci"- 

Where : — 
^^  ^  /DoB, +  77oBo\  ^^^  ^  /,/,A>o  +  ^.Vo\     ^,  ^  ^,  ^^^ 

\        2  Bo  Bo        )  \  AV  -H  AV    / 

_        .( DoBo-DoB,\  ^         /d^Xo-d2Xo\ 

\       zBoBo        /  \    y?,r-|-AV    / 


Bo  Bo 


Es  Er 


flEti    Er 


Cr 


y  Ro'  +AV 

Reference  to  equations  (5)  to  (10)  gives  the  supply  and 
receiver    circle    diagram     constants     with    phase     to     neutral 

♦Where  capital  subscripts  are  used  in  this  article  line 
quantities  are  referred  to  and  small  subscript,  phase  quanti- 
ties (phase  to  neutral).  P  and  Q  are  expressed  in  watts  and 
volt-amperes  respectively. 


voltages  quantities  when  P  and  Q  are  expressed  in  kv-a. 
Fig.  I  shows  the  way  in  which  the  diagram  may  be  plotted 
and  the  quadrants  in  which  the  respective  circles  lie. 

Loss  Equations 
The  losses  of  a  transmission  network  are  equal  to  the  dif- 
ference of  the  power  supplied  to  it  and  that  delivered.  In 
other  words,  the  loss  is  equal  to  the  difference  of  the  real  com- 
ponents in  the  following  expression  with  £a  used  as  a  refer- 
ence vector : — 

Total  loss  =  3  E,Z  -  3  E,~  =  {Ps-Pn)  -\-  j  ((?s-(?n) 

p^  ^  (b^o±11^^  A„n.+A„D\p^^jAlo+^^j,^^^ 

(BoTjo -{-ITo  Do\  J  ( AoDo-AoDo      B.Z'o  -  B„Co\  n 

and  Pr  =  Fi,. 

Then  Ps—Pr=  total  loss  =  tPBi-uEa''+3vh'+wQ.  . 
which  is  the  same  as  equation  (ii),  where, — 

o-\-X'ob„-^aidi-{-a-jfi~j 


^  ^B„Co+B„Co_^AoDo-h'AoDo_\_^ 
„   _/-Ao'Co+'AoCo\ 
{BoDoJrBoDo\ 


=  a\go  -\-  Hi  ho 


=  (/i  /?„  -I-  di  Xo 
^  _   \{B,7:o-BoCo)  _  {AoDo^-^oDo)^ 


a-,  d\ 


=  Xogo  -  Kobo-\-axd2 
An   e-xpression    for   transmission   loss    similar   to   equation 
(11)    can  be  derived   in  terms  of   the  load  conditions  at  the 
supply  end  with  £s  used  as  a  reference  vector. 

Total  loss  =  -  tP^-^  u'  Es-  -[■  3V'  I^-  -  w'  Qs (/.?) 

(Di^,  +  DoCo\ 

: j  =  d,^o  +  d..bu 


Where  «' 


(^ 


(BoAo-{-   B„Ao\  r,       ,  X. 

^,  ^  _  ,-UPM,-iroCo)  ^  (AoDo-AoDo) 


=  A'o^o  —  Bo  bo  -i-  Hidi  —  Ui  d-2 
The  only  difference  in  the  two  expressions  is  in  the  con- 
stants of  the  last  three  terms  and  the  sign  of  the  first  and 
last  terms  and  this  can  be  explained  by  the  fact  that  power 
supplied  to  the  circuit  is  the  same  as  a  negative  load  so  that 
the  two  equations  are  the  same.*  The  fourth  term  of  the 
two  loss  expressions  involves  reactive  volt  amperes,  which 
has  been  previously  defined  in  a  foot  note  as  positive  for 
lagging  and  negative  for  leading. 

It  is  to  be  noted  that  these  constants  simplify  a  great  deal 
for  a  transmission  line  alone  when  leakage  is  neglected.  For 
these  conditions,  the  constants  become: — 

i  =  o  (an  approximation) 

u  =  U'lbo  =  n' 

V  =  ai  Ro  ■{■  rtL'  A'o  =  v' 

7t'  =  —  Ro  bu  =  re' 

Loss  Circle  Diagram 

For  the  purpose  of  determining  the  loss  circle  diagram, 
equation  (11)  may  be  written  as  follows: — 

Lr   =   t  Br  -{■  uBr-  -f  V  ^r-j +    U)  Qr (/j) 

This  may  be  expanded  and  symplified  to  give  the  equation  of 
a  circle : — 

(pr  -h  -L^  E^{-  j  -t-  ^  Cr  -I-  il  Er^  \  = 


-I-    {P    -I-    u!'- 


.-of^) 


*It  should  be  noted  that  the  only  difference  in  the  con- 
stants of  the  last  three  terms  is  with  regard  to  the  interchange 
of  the  Ao  and  Do  constants.  The  reason  for  this  may  be  seen 
in  equations  (i)  to  (4)  where  Ao  and  Do  were  originally  in- 
terchanged. This  also  applies  to  the  difference  of  the  I,  m 
and   /',   m'    constants. 


536 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


from  which  the  position  of  the  center  and  the  radius  are  self- 
evident  and  are  as  given  in  the  main  part  of  this  article. 

A  similar  set  of  circles  for  the  supply  end  can  be  deter- 
mined from  equation  (12)  or  written  from  similarity  to  the 
equation  above  by  changing  the  signs  of  the  t  and  zf  con- 
stants, changing  the  subscripts  R  to  s  and  changing  u,  v,  xu,  to 
V.' ,  v  ,  w' .    This  gives: — 

Efficiency  Circle  Diagram 
For  the  purpose  of  determining  the  equation  for  the  ef- 
ficiency diagram  the  transmission  losses  may  be  expressed  as 
Pb  (100/ t) — l"),  where  t)  is  the  percent  efficiency,  and  substi- 
tuted in  equation  (13)  for  L-r.  The  resulting  equation  may 
be  expanded  and  simplified  to  give  the  equation  of  a  circle. 

h+-¥('-<f-'>)]'+l'^"+^«]'= 


-f  iP^-ur- 


4  '■  -/ 


[f^^xlO 


'>y 


-\-ztfl~  I  u 


\ 


.  ('./) 


from  which   the  location  of   the  center  and  the   radius   is  as 
given  in  the  main  part  of  this  article. 

A  similar  set  of  circles  for  the  supply  end  can  also  be 
written  from  similarity  by  changing  the  subscripts  R  to  s, 
changing  the  signs  of  the  (  and  w  constants  and  changing  u, 
V,  zu  to  »',  v' ,  li',  and  also  remembering  that  the  expression 
(100/ -^—i)  now  becomes  (i— "r, /loo).     This  gives:— 


[;i7V(/+  ('-. 


-)  I  +w'—^v'u' 


.  (/5) 


The  point  of  maximum  efficiency  is  the  point  where  the 
radius  becomes  equal  to  zero.  This  gives  from  equations  (14) 
and  (15)  :— 

(/OO  \  .  

/-(—-/)  jand   ±i/,(«'c/-rc'2  = 

-('  +  ('-73.)) 
Substituting  in  equation   (14)   gives: — 

[''"  +  7F  •    ^  "  "  -  "■'] '+  [^^  +  ^  ^«'  ]  "  =  " 
and  in  equation  15  gives  :- 

Each  of  these  equations  has  two  solutions,  one  for  positive 
power  and  the  other  negative  power.  The  real  points  for  po- 
sitive power  will  fall  in  the  first  and  fourth  quadrants  for  the 
supply  and  receiver  ends  respectively  as  given  by  the  above 
expressions,  when  considering  the  minus  root  of  the  radical  in 
the  tirst  term.  Somewhat  more  simplification  in  plotting  can 
be  obtained  by  expressing  the  above  in  a  ratio  of  P  to  Q. 

The  j  term  is  not  involved  in  any  of  the  final  expressions 
for  the  circle  diagrams  because  the  constants  /,  /',  m,  m'  n,  t,  «, 
H,'  V,  V,'  IV  and  «''  have  included  it.  /*n,  /^s,  Qk,  Qs,  A'r,  /is,  A, 
and  /.  should  be  taken  as  scalar  quantities  in  these  final  ex- 
pressions for  the  loss  equations  and  the  voltage-power,  loss 
and  efficiency  diagrams. 


q\[o. 


77;^  £^ 


r 


riu) 


Dry  Coll  Radio   Vacintm  Tubs 


HARRY  M.  RYDFR 

Research  Laboratory, 
Westinghouse  Electric  &  Mfg.  Company 


THE  owner  of  a  radio  receiving  outfit  is  aware  of 
the  advantages  to  be  obtained  by  using  one  or 
more  vacuum  tubes  in  the  circuit,  if  other  than 
verj'  strong  signals  are  to  be  heard,  or  if  a  loud  speak- 
ing device  is  to  be  used.  Many  have  foregone  these 
advantages,  however,  on  account  of  the  expense  or  in- 
convenience of  the  accessories,  particularly  the  battery 
nece-ssary  to  supply  the  filament  energ)-.  As  most 
tubes  available  have  filaments  requiring  a  current  of 
from  0.6  to  i.o  ampere,  at  from  four  to  six  volts,  a  six 
volt  storage  batteiy  has  been  the  only  satisfactory 
source.  This  has  meant  the  presence  of  acids,  an  ex- 
pensive batterv  and  the  necessity  of  charging  at  inter- 
vals. 

A  new  tube  has  recently  been  developed,  which 
makes  the  use  of  a  storage  battery  unnecessary.  Fig. 
1  shows  the  tube  reproduced  to  two-thirds  actual  si7e. 
It  is  somewhat  smalle:-  than  most  tubes  and  fitted  with 
a  base  designed  to  prevent  its  being  accidently 
placed  in  a  socket  supplied  by  a  six  volt  battery  and 
thereby  having  its  filament  ruined.  This  base  is  also 
designed  to  prevent  the  accidental  connecting  of  the 
plate  potential  to  the  filament  terminals. 

The  filament  requires  but  i.i  volt  to  operate  and 
uses  0.2  ampere  continuously.  This  means  a  power 
consumption  of  less  than  one  fourth  watt  as  compared 
with  3  to  5  watts  in  the  ordinaiy  tube  filament.  For 
this  reason  it  is  possible  to  operate  the  filament  from 


a  single  dry  cell  and  avoid  the  greater  expense  and 
trouble  incident  to  the  u«e  of  a  storage  batteiT.  In 
addition  to  this  advantage,  a  plate  battery  of  22  volts 
is  sufficient  for  all  work,  except  where  tlie  utmost  m 
signal  strength  is  required,  in  which  case  a  plate  po- 
tential of  30  volts  will  give  slightly  better  results.  A 
higher  potential  than  this  is  never  necessary  and  a  po- 
tential above  22  volts  is  seldom  needed,  hence  this  tube 
makes  unnecessary  the  use  of  a  second  B  battery  block, 
and  the  expense  incident  to  it.  Again,  the  tube  is  hard, 
so  that  the  plate  voltage  adjustment  is  not  critical,  no 
adjustment  being  necessary  on  that  account. 

An  idea  of  how  long  a  dry  battery  should  last  in 
the  service  required  by  this  tube,  is  given  in  Figs  2 
and  3.  In  both  cases  it  has  been  assumed  that  the  tube 
is  to  be  operated  one  hour  out  of  each  twenty-four 
Fig  4  is  added  to  show  how  the  power  obtained  from 
a  single  No.  6  dry  cell  will  vary  with  the  rate  at  which 
the  dr>'  cell  is  drawn  upon.  Thus,  if  several  dry  cells 
in  series  were  used  to  supply  a  filament  requiring  O.S 
ampere,  only  five  ampere-hours  would  be  available 
from  each  cell  before  its  voltage  would  have  dropped 
to  one  volt  at  the  end  of  a  one  hour  run,  while  22  am- 
pere-hours would  be  available  for  supplying  a  filament 
requiring  0.2  amperes  before  the  voltage  would  take  a 
corresponding  drop. 

This  information  illustrates  the  wonderful  possi- 
bilities of  this  tube  in  a  portable  receiving  outfit.     It 


Decembei",  1921 


THE  ELECTRIC  JOURNAL 


537 


is  probable  that  more  such  outfits  were  carried  to  camp 
during  the  summer  of  192 1  than  during  any  previous 
season,  in  spite  of  the  Hmitations  imposed  by  a  storage 
battery.     This  "dry  cell"  tube  now  makes  it  practica- 


FIG.    I — NEW   VACUUM   TUBE  REQUIRING   LESS   THAN   0.25   WATT    FOR 
HEATING  FILAMENT 

ble  for  a  party  on  an  extended  canoe  trip  into  the  wilds 
of  Canada  to  carry  with  them  a  receiving  set  of  small 
dimensions  and  weight,  and  of  sufficient  range  to  keep 
in  touch  with  world  affairs.  With  the  present  radio- 
phone broad-casting  of  market  and  stock  reports,  and 
the  Post  Office  Department's  proposed  extension  of 
this    method   of    announcement,    it   is    not   necessary 


-.. 

^ 

^ 

^ 

V" 

x^ 

^ 

sJ 

■i" 

LSa 

\ 

"^ 

s^. 

hij". 

f , 

. 

\ 

\ 

\ 

k 

'^ 

■~~> 

■ 1 

> 

% 

sJ 

^ 

^ 

.^^ 

\ 

^ 

-1.0 

\ 

\ 

\ 

-..J 

\ 

i 

\ 

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3 

0.  of 

One 

iOUr 

Load 

1 
Run^ 

Olf 

Amfl 

,      ' 

u 

^ 

r 

FIG.    2 — VOLTAQES    OF   DRY    CELLS    .\T    THE    ENDS    OF    SUCCESSIVE 
ONE-HOUR    RUN 

that  a  man  become  an  expert  at  copying  code  in  order 
to  take  advantage  of  such  opportunities. 

The  advantage  is  not  limited,  however,  to  the  por- 
table set.  In  the  home,  a  dry  cell  is  always  to  be  de- 
sired in  preference  to  a  storage  batterj-,  not  only  on 
the  score  of  economy,  but  also  because  a  dry  cell  may 
be  located  in  any  convenient  place. 

It  is  logical  to  ask  how  this  great  decrease  in  fila- 


ment power  consumption  has  been  accomplished.  The 
design  of  every  essential  element  in  the  tube  contri- 
butes to  this  end.  Fig.  5  shows  the  interior  arrange- 
ment and  Fig.  6  the  elements  which  go  to  make  up  this 
structure.  The  filament  is  of  platinum,  about  one- 
eighth  as  thick  as  fine  tissue  paper,  and  one  one-hun- 
dredth of  an  inch  wide.  This  is  coated  with  a  very 
thin  layer  of  certain  oxides  with  the  result  that  a  spe- 
cial  form  of  Wehnelt  cathode   is   formed.     This   fila- 


-^ 

V 

■ 

r^ 

s 

s 

— ' 

^ 

~_ 

-£!aL=nt  iu  aL„. 

^ 

^.. 

--H 

— 

-  1 

r 

t 

°Tin,.,n* 

•linutcs 

e„ 

T 

FIG.   3 — DROP  IN  VOLTAGE  DURING  RUN  OF  A   NO.  4  DRY  CELL  WHICH 
IS    NEARLY   EXHAUSTED 

ment  is  welded  to  end  supports  for  easy  assembly,  and 
is  kept  in  position  by  the  aid  of  a  specially  constructed 
and  very  flexible  form  of  spring.  This  spring  en- 
ables the  filament  to  move  freely  in  case  of  a  severe 
jar,  but  otherwise  to  be  held  firmly  in  place.  It  re- 
sults in  an  exceedingly  rugged  structure  for  so  delicate 
a  strip.  The  grid  and  plate  are  of  the  common  forms 
except  that  very  small  and  exact  dimensions  must  be 
used.  If  accuracy  and  inspection  were  not  carefully 
maintained,  inoperative  tubes  would  result.  The  as- 
sembly is  centered  about  the  electric  welding  ma- 
chine. Fig  7,  and  this  operation  has  been  refined  to  a 
veiy  high  degree  to  make  possible  such  products  as  are 
represented  in  tliis  tube.  The  final  operation  in  obtain- 
ing this    tube   is  performed  by  the    exhaust   system. 


\ 

^0 

y 

\ 

V 

!-'■ 

\ 

\ 

< 

\ 

V 

■-^ 

,^ 

' 

Ji 

T 

0, 

1.0 

d  Ci 

05 
rrentiAmp 

.» 

6     - 

J 

' 

0 

'        i 

FIG.   4 — POWER  AVAILABLE  FROM  A   NO.   6  DRY  CELL  WHEN  OPERATED 
FOR  ONE  HOUR  A   DAY,   WITH   A  FINAL  VOLTAGE  OF    I.I   VOLTS 

Here  special  apparatus  and  special  schedules  have  been 
developed  to  make  possible  a  tube  of  high  quality  and 
uniformity. 

A  characteristic  curve  for  this  tube.  Fig.  8  shows 
that  the  unusual  filament  and  plate  structure  and  di- 
mensions have  in  no  way  produced  undesirable  varia- 


538 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


tions  in  this  curve.  The  amplification  factor  is  approxi- 
mately seven  and  a  plate  impedance  of  about  22  000 
ohms  is  obtained,  making  it  possible  to  insert  this  tube 
in  any  of  the  usual  circuits  designed  for  a  low  imped- 


FIG.    5 — ASSEMBLED   ELECTRODES   OF   THE    NEW    VACUUM    TUBE 


ance  tube,  without  fear  of  unsatisfactory  operation. 

In  operation,  the  low  voltage  and  power  require- 
ments of  this  tube  make  certain  precautions  necessary 
to  the  uninitiated  user.  The  filament  operates  at  a  low 
red  heat  instead  of  at  the  bright  point  to  which  users 
of  tungsten  filament  tubes  are  accustomed.     If  a  six 


FIG.  6 — PARTS  OF  THE  NEW  VACUUM  TUBE 

volt  battery  were  to  supply  power  to  this  filament  with 
only  the  usual  six  ohm  rheostat  in  series,  the  filament 
would  have  a  very  short  life,  since  the  rheostat  would 
not  have  sufficient  resistance  to  cut  down  the  current 


to  the  proper  value.  At  a  bright  yellow  heat  this  fila- 
ment will  deteriorate  rapidly,  even  though  the  inexper- 
ienced eye  may  consider  it  to  be  operating  at  a  conser- 
vative temperature.  It  is  necessary,  therefore,  until 
the  operator  is  well  acquainted  with  this  tube,  that  he 
take  special  precautions  to  maintain  the  filament  cur- 
rent at  the   lowest    value   which   will   give    full    signal 


FIG.  7 — ASSEMBLING  THE  PARTS  ON  AN  ELECTRIC  WELDING  MACHINE 

Strength.  The  filament  will  give  no  warning,  such  as 
a  bright  light,  or  noise  in  the  phones,  when  it  is  being 
operated  beyond  its  proper  temperature,  so  that  the  re- 
sponsibility for  a  long  filament  life  lies  with  the  opera- 
tor in  making  the  proper  rheostat  adjustments,  unless 
a  ballast  lamp  is  used.  If  this  simple  rule  is  followed, 
the  user  of  this  tube  will  find  that  he  has  a  new  device 
which  will  not  only  make  good  radio  operation  more 


/ 

/ 

. 

/ 

/ 

—& 

/ 

/ 

J 

( 

/ 

^ 

7 

/ 

1 

f 

/ 

3 

7 

/ 

/ 

/ 

/ 

/ 

f^ 

y 

1 J 

rid  1 

oiac 

* 

FIG.   8— CHARACTERISTIC  CURVES   OF   PLATE  CURRENTS   AT 
TWO  PLATE  VOLTAGES 

economical,  but  will  enable  him  to  enjoy  it  witli  much 
less  attention  to  the  accessories,  and  in  places  where 
he  had  not  thought  it  possible  to  carry  a  set. 


2 


G.  C    HECKER 

General  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


WITH  the  development  of  large  generating  units 
and  the  increase  in  efficiencies,  there  has  been 
a  tremendous  growth  of  the  central  station 
power  companies  in  the  past  ten  or  fifteen  years.  As 
a  result  of  this  growth  and  increased  efficiency  of  gen- 
eration, many  electric  railways  have  found  it  expedi- 
ent to  purchase  power  and  either  sell  or  scrap  their 
generating  equipment.  In  a  considerable  portion  of 
the  United  States,  the  standard  frequency  for  lighting 
and  power  is  60  cycles.  Numerous  electric  railways 
throughout  the  country  generate  at  25  cycles  and  use 
25  cycle  converting  equipment  in  their  substatioriS. 
Where  such  a  company,  located  in  a  60  cycle  power 
district,  finds  it  expedient  to  purchase  power,  it  is  con- 
fronted with  the  problem  of  equipping  its  substations 
to  utilize  60  cycle  power. 

Although  in  a  few  isolated  cases  it  may  prove 
economical  to  retain  the  25  cycle  converting  apparatus 
and  supply  the  system  through  frequency  changers,  it 
will  usually  be  found  advisable  to  make  such  changes 
as  are  necessary  in  the  converting  equipment  to  per- 
mit operation  at  60  cycles.  When  such  a  change  is 
contemplated  the  question  arises  as  to  how  much  of 
the  25  cycle  equipment  can  be  used  and  what  changes, 
if  any,  will  be  required  to  make  it  suitable  for  60  cy- 
cle operation. 

Although  it  is  not  possible  to  formulate  definite 
rules  covering  all  cases,  the  principal  considerations  in- 
volved are  outlined  below  and,  in  general,  this  outline 
will  serve  to  indicate  the  conditions  most  frequentlv  en- 
countered. 

SYNCHRONOUS   CONVERTERS 

In  making  such  a  change  there  is,  quite  naturall}', 
a  desire  to  rebuild  the  synchronous  converters  for  60 
cycles.  In  a  number  of  cases  this  problem  has  been 
invesigated,  and  it  has  not  been  found  practicable  to 
rebuild  23  cycle  converters  for  60  cycle  operation. 
From  an  economic  point  of  view,  there  is  practically 
nothing  to  be  saved  in  first  cost.  As  a  matter  of  fact. 
the  expense  involved  is  apt  to  result  in  a  cost  even 
higher  than  that  of  new  60  cycle  units.  This  will  be 
appreciated  when  it  is  realized  that  such  a  change  ne- 
cessitates the  manufacture  of  special  parts  for  the  ex- 
isting machines,  as  about  the  only  parts  of  the  25  cycle 


unit  and,  furthermore,  it  is  impossible  to  include  many 
of  the  improvements  embodied  in  the  modern  60  cycle 
converter  which  are  so  essential  to  its  good  perform- 
ance. 

The  six-phase  synchronous  converter  has  become 
the  standard  for  both  25  and  60  cycles,  because  of  its 
higher  efficiency  and  greater  output  for  a  given  arma- 
ture winding.  Many  three-phase  and  some  two-phase 
converters  were  built  before  the  development  of  the 
si.x-phase  machine  and  quite  a  few  of  these  machines- 
are  still  in  operation.  Therefore,  in  substituting 
modern  six-phase  converters,  several  problems  are 
encountered,  relating  to  the  proper  alternating-current 
voltage  and  grouping  of  transformers,  which  are  dis- 

TABLE    I— \'OLTAGE    RATIOS    AND    ALTERNATING 
CURRENT  AMPERES 


.\pprox. 

Approx.  Ratio 

Amps,  per  Ring 

No.  of  Phases 

Rmgs 

A.  C.  to  D.  C. 

in  Percent  of  D.  C. 

Voltages 

Amperes 

Single 

2 

0.71 

ISO 

Three 

^ 

0.6  r 

100 

Two 

4 

0.71 

75 

Six    (diametrical) 

6 

0.71 

50 

Six  (double  delta) 

6 

0.61 

50 

cussed  in  detail  under  the  heading  of  transforiners. 
Table  I  shows  the  theoretical  no-load  ratios  between  al- 
ternating-current and  direct-current  voltages  in  syn- 
chronous converters  and  also  the  values  of  alternating 
current  per  ring,  expressed  in  percent* of  the  cor- 
responding direct  current  amperes. 

TR.'iiNSFORMEES 

In  general,  a  25  cycle  transformer  of  the  type  used 
in  railway  converter  work,  will  deliver  its  rated  kv-a, 
at  its  rated  voltage  on  (3o  cycles,  without  exceeding  a 
safe  temperature.  With  the  same  impressed  voltage 
in  each  case,  the  core  losses  on  60  cycles  will  be  less 
than  on  25  cycles,  due  to  the  lower,  flux  density.  The 
copper  losses  will  be  soinewhat  higher  on  (5o  cycles,  due 
to  the  increased  eddy  current  losses.  However,  the 
eddy  current  losses  in  the  copper  are  usually  but  a 
small  percentage  of  the  total  copper  losses,  and  the  in- 
crease generally  may  be  neglected,  as  it  is  more  thani 
counter-balanced  by  the  decrease  in  core  losses. 

Modern  transformers  for  railway  converter  woi'k 
are  designed  with  approxiinately  15  percent  reactance. 


units  which  can  be  used  are  the  frames  and  bedplates  except  where  this  value  is  not  suitable  for  parallel  op- 

and    in    some    cases    the    bearing    pedestals.     Second,  eration   of    the    converter    with    existing    converters, 

the  possibilities  of  obtaining  good  operating  character-  Many  of  the  earlier  transformers  have  relatively  low 

istics  are  rather  remote,  as  the  old   parts    do   not   lend  reactance  values,  and  when  changed  from  25  to  60  cy- 

themselves  particularly  well  to  the  design  of  a  (5o  cycle  cle  operation,   the  reactance,  which   varies  directly  as 


540 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


the  frequency,  will  not  be  greater  than  15  percent. 
Special  attention  must  be  given  reactance  values  when 
parallel  operation  of  converters  is  involved  and  occas- 
sionally  it  may  be  found  necessary  to  install  reactance 
■coils  in  the  leads  of  converters  having  unusually  low 
reactance  transformers.  If  the  transformer  reactance 
is  unusually  high  when  operated  on  60  cycles,  it  is  ad- 
visable to  consult  the  manufacturer  of  the  converter 
regarding  its  performance  under  such  conditions. 

The  reactance  of  a  transformer  varies  also  as  tb.e 
square  of  the  total  number  of  turns  in  the  coils. 
Therefore,  if  there  are  any  full  capacity,  reduced  volt- 
age taps,  on  the  high  and  low  voltage  windings,  it  may 
be  possible  to  reduce  the  reactance,  if  necessary,  by  op- 
erating on  suitable  taps.  In  some  cases  this  can  be  done 
without  affecting  the  ratio  of  transformation.  Natur- 
ally this  method  has  limitations  beyond  which  it  is  un- 
safe to  go,  but  generally  any  full  capacity  taps  may  be 
used. 

If  the  25  cycle  converter  to  be  replaced  is  a  si.-:- 
phase  machine,  of  course  the  voltage  of  the  existing 
transformers  will  be  correct  for  the  standard  six-phase, 
60  cycle  unit.  However,  if  a  three-phase  machine  is 
being  replaced,  the  voltage  delivered  by  its  transform- 
ers will  be  too  low  for  the  operation  of  the  six-phase, 
60  cycle  unit,  assuming  that  the  same  direct-current 
voltage  is  to  be  maintained.  It  may  be  possible  to 
obtain  the  necessary  increase  in  voltage  by  operating 
the  transformers  on  reduced  voltage  taps  on  the  high- 
voltage  winding.  However,  if  suitable  taps  on  the 
high-voltage  winding  are  not  available,  and  it  is  nf)i 
practicable  to  bring  out  such  taps,  the  converter  may 
be  arranged  for  three-phase  operation.  This  may  be 
done  by  removing  the  taps  to  the  armature  windiriF 
from  alternate  collector  rings  and  paralleling  each  of 
the  remainini;  rings  with  an  idle  one.  This  leaves  the 
armature  connected  to  the  collector  rings  in  the  proper 
three-phase  relationship  and  provides  the  necessaiy 
brush  capacity  for  three-phase  operation. 

It  should  be  realized  that  three-phase  operation 
of  a  given  six-phase  converter  reduces  its  therm;>l 
capacity.  Its  ability  to  comniutate  momentary  loads, 
however,  is  not  affected.  Therefore  in  interurban 
work,  where  the  size  of  the  substation  units  is  deter- 
mined on  the  basis  of  the  heaviest  momentary  peaks, 
and  where  the  integrated  loads  are  but  a  small  percent- 
age of  the  converter  ratings,  the  reduction  in  thermal 
capacit}'  is  of  small  consequence.  In  city  work, 
however,  where  converters  are  fully  loaded  for  long 
periods  followed  by  overloads  of  several  hours  dura- 
tion, the  reduction  in  thermal  capacity  is  of  importance, 
and  should  be  given  careful  consideration. 

If  the  converter  being  replaced  is  a  two-phase  ma- 
chine, its  transformers  are  wound  for  the  proper  volt- 
age for  a  six-phase  diametrically-connnected  converter 
but,  in  order  to  obtain  the  full  capacity  of  the  existing 
transformers  and  the  nevir  six-phase  converter  it  will 
be  necessary  to  install  a  third  transformer.     This  re- 


sults in  an  increase  of  50  percent  in  transformer  capa- 
city and  permits  the  installation  of  a  correspondmgly 
larger  converter.  This  may  prove  desirable  in  some 
cases,  while  in  others  the  cost  may  be  prohibitive.  Al- 
though it  is  possible  to  operate  the  converter  on  two 
transformers,  its  thermal  capacity  will  be  lowered  ap- 
proximately 35  percent.  The  commutation  of  the 
converter  will  not  be  affected,  within  the  range  cf 
the  usual  ratings,  and  therefore  in  interurban  work, ' 
this  arrangement  may  prove  quite  satisfactory.  In 
cUy  work,  however,  the  better  plan  is  to  add  a  third 
transformer  to  each  bank.  It  is  of  interest  to  note 
that  in  a  station  having  three,  25  cycle,  two-phase  con- 
verters, the  transformers  could  be  re-grouped  into 
two  three-phase  banks  and  two  larger  converters  in- 
stalled without  in  any  way  affecting  the  station  capaci- 
ty. With  the  larger  converters,  heavier  switching 
equipment  probably  would  be  necessary. 

Where  the  converters  being  replaced  are  of  the  rl- 
ternating-current  self-starting  type,  the  starting  taps  on 
the  existing  transformers  should  be  satisfactory  for 
starting  the  60  cycle  converters.  However,  if  the  old 
25  cycle  converters  are  motor  started,  the  existi.ig 
transformers  probably  will  not  have  starting  taps. 
The  modern  alternating-current  self-starting  converter 
requires  approximately  one-third  voltage  at  the  collec- 
tor rings  when  starting.  In  many  existing  transform- 
ers it  may  be  difficult,  or  impracticable  to  bring  out 
one-third  voltage  taps  on  the  low-voltage  windings. 
In  most  cases,  however,  it  is  not  difficult  to  bring  out 
30  percent  taps  from  cross-over  connections  between 
the  low-voltage  coils,  which  will  be  satisfactory  for 
starting  the  converter,  provided  the  increased  kv-a 
drawn  in  starting  does  not  produce  too  great  fluctua- 
tions in  the  transmission  voltage.  If  the  increase  in 
kv-a  resulting  from  the  higher  starting  voltage  is  ob- 
jectionable, it  may  be  limited  by  inserting  resistance  or 
reactance  in  the  converter  leads  in  starting. 

Direct-current  starting  may  be  resorted  to,  if  di- 
rect-current power  is  always  available  and  if  the  direc:- 
current  voltage  is  fairly  constant,  so  that  synchronizing 
is  possible.  If  the  direct-current  supply  fluctuates  bad- 
ly, it  may  be  desirable  to  bring  the  machine  up  to  ap- 
proximate speed  and,  after  opening  the  direct-current 
switches,  connect  the  converter  to  the  transformers 
through  a  suitable  reactance,  which  may  be  short-cir- 
cuited or  cut  out  when  the  machine  has  pulled  into 
synchronism. 

CURRENT  AND  P0TI:NTI.\L  TRANSFORMERS 

In  current  transformers,  a  change  in  frequency 
from  25  to  60  cycles  reduces  the  magnetizing  current, 
therebv  tending  to  reduce  the  ratio  and  phase  errors. 
In  a  potential  transformer  the  change  from  25  to  60 
cvcles  affects  the  accuracy  but  slightly.  In  fact,  both 
current  and  potential  transformers  are  so  accurate  thai 
the  variation  in  error,  due  to  a  change  in  frequency 
from  25  to  60  cycles,  usually  is  negligible. 


December,  1921 


THE   ELECTRIC  JOURNAL 


541 


INSTRUMENTS   AND  RELAYS 

Most  25  cycle  instruments  and  relays  in  service  at 
the  present  time  will  require  re-calibration  for  use  on 
60  cycles.  The  expense  of  the  re-calibration  is  small, 
especially  if  the  operating  company  is  equipped  to  han- 
dle such  work.  Even  though  the  instruments  and  relays 
are  returned  to  the  factory  for  re-calibration,  the  cost 
is  low  compared  with  that  of  new  apparatus. 

SWITCHBOARDS 

The  change  in  frequency  in  itself  will  not  affect 
the  switchboard  or  the  wiring,  but  the  use  of  a  six- 
lihase,  alternating-current,  self-starting  converter  may 
require  some  changes.  For  example  if  a  motor-started 
converter  is  being  replaced  by  a  six-phase,  alternating- 
current  self -starting  unit,  the  motor  switch  and  wiring, 
main  alternating-current  converter  switch  and  the 
synchroscope,  synchronizing  receptacles  and  wiring 
may  be  removed.  A  three-pole,  double-throw,  starting 
switch  and  a  two-pole,  double-throw,  field  reversal 
switch,  with  discharge  clip  and  discharge  resistance, 
must  be  installed.  In  some  cases  this  apparatus,  to- 
gether with  a  small  differential  voltmeter  for  determin- 
ing the  converter  polarity,  may  be  mounted  on  a  sepa- 
rate panel  located  near  the  transformers,  thus  simplify- 
ing the  work  and  reducing  the  amount  of  cable  and 
wire    required. 

GENERAL 

It  should  be  realized  that  in  changing  from  25  zy- 
cle  operation  additional  operating  problems  are  pre- 
sented. As  is  well  known,  the  design  problems  in  a  23 
cycle  converter  are  simpler  than  in  a  60  cycle  con- 
verter, since  the  design  inherently  allows  greater  clear- 
ances and  creepage  distances  and,  in  general,  fewer 
space  limitations  are  encountered.  For  the  best  re- 
sults, therefore,  it  is  important  that  the  60  cycle  ma- 
chines be  kept  thoroughly  clean,  the  commutator  and 
brushes  in  good  condition  and  the  spacing  and  align- 
ment of  brushholders  properly  maintained.  Also  it  is 
important  that  proper  protective  devices  be  provided 
and  that  these  devices  be  carefully  adjusted  and  kept 
in  good  working  order.  From  the  above  the  impres- 
sion should  not  be  obtained  that  the  60  cvcle  converter 
is  not  a  thoroughly  satisfactory  unit,  as  the  contrary 
ir.  proven  by  the  large  number  of  60  cycle  units  in  satis- 
factor\-  service.  It  is,  however,  intended  to  point 
out  that  the  different  conditions  must  be  prop- 
erly handled  in  order  to  obtain  the  best  results. 

Many  of  the  earlier  converters  are  qrn'te  liberal!,- 
rated,  as  design  problems  in  those  days  were  not  so  well 
understood  as  they  are  today,  and  rather  large  factor.-; 
ot  safety  were  used.  Modern  synchronous  converte's 
closely  duplicate  the  calculated  performance,  with  the 
result  that  a  nameplate  rating  of  say  500  kw,  means 
that  the  machine  will  deliver  that  output,  with  such  ov- 
erload as  may  be  specified,  with  only  a  reasonable  mar- 
gin of  safety.  Therefore  in  choosing  new  units,  the 
actual   load  conditions,  rather  than  the  nameplate  rat- 


ing of  the  existing  machines,  should  govern  the  size  of 
units  selected. 

A  sychronous  converter  should  be  provided  with  an 
automatic  oil  circuit  breaker  connected,  preferably,  m 
the  hightension  leads  of  the  transformers.  The  oil  cir- 
cuit breaker  should  be  equipped  with  instantaneous 
overload  trip,  low-voltage  release  attachment  and  an 
auxiliary  switch  attachment.  The  latter  device  should 
be  connected  so  as  to  short-circuit  the  low-voltage  coil 
of  the  direct-current  machine  circuit  breaker,  thus  in- 
suring that  the  machine  will  be  disconnected  from  the 
direct-current  bus  whenever  the  alternating-current 
breaker  opens. 

The  proper  setting  of  the  alternating  and  direct- 
current  machine  circuit  breakers  is  of  great  im- 
portance if  the  best  results  are  to  be  obtained.  The 
modern  converter  will  commutate  large  momentary 
currents,  provided  the  direct-current  machine  circuit 
breaker  does  not  open,  while  almost  invariably  the  con- 
verter will  flash  at  no  greater  loads,  if  the  direct- 
current  machine  circuit  breaker  opens.  Therefore  it 
is  desirable  to  have  a  high  setting  of  the  direct-current 
machine  circuit  breaker,  particularly  where  there  are 
several  feeder  circuits.  The  feeder  circuit  breakers 
should  be  equipped  with  instantaneous  trip  and  set 
sufficiently  low  to  pennit  selective  action  between  them 
and  the  direct-current  machine  circuit  breaker,  so  as 
to  prevent  the  entire  load  being  cut  off  the  converter 
instantaneously. 

In  smaller  stations,  where  there  are  no  feeder 
panels,  the  tendency  is  toward  making  the  direct-cur- 
rent circuit  breaker  non-automatic  and  protecting  the 
converter  entirely  by  means  of  the  oil  circuit  breaker 
The  direct-current  circuit  breaker  then  is  equipped 
only  with  a  low-voltage  release  coil,  which  is  used  to  in- 
terlock with  the  oil  circuit  breaker,  as  previously  men- 
tioned. 

In  large  stations,  the  converter  capacities  in  serv- 
ice are  usually  great  enough  to  commutate  most  short- 
circuits  on  the  distribution  system,  and  selective  actio.i 
between  the  feeder  breakers  and  machine  breakers  is 
not  at  all  difficult  to  obtain. 

A  synchronous  converter  also  should  be  equipped 
with  a  direct-current  reverse-current  relay,  overspeed 
device  and  power-factor  meter,  all  of  which  are  essen- 
tial to  the  proper  protection  of  the  machine. 

The  importance  of  having  some  resistance  between 
the  converter  and  the  trolley  is  now  generally 
recognized.  This  may  be  most  easily  accomplished  bv 
removing  the  feeder  taps  near  the  station.  Obviously, 
the  distance  to  the  first  feeder  tap  will  vary,  depending 
on  the  size  of  feeders,  capacity  of  the  converter,  capa- 
city of  the  generating  system  and  other  factors,  but  in 
any  case,  feeder  taps  close  to  the  station  should  be  re- 
moved and  the  distance  between  the  station  and  the 
first  feeder  tap  increased  until  flashing  from  this  source 
is  eliminated.  Generally,  this  distance,  for  600  volt 
interurban  systems,  will  not  be  less  than  2000  feet. 


Civ'Cdlcs.Xyil 


.iV(>)'(jii'.}rs  for  Volia^n  Control 

\\M.  NESBir 


WITH  alternating-current  transmission  there  is 
a  voltage  drop  resulting  from  the  resistance 
of  the  conductors,  which  is  in  phase  with  the 
current.  In  addition  there  is  a  reactance  voltage  drop ; 
that  is  a  voltage  of  self-induction  generated  within  the 
conductors  which  varies  with  and  is  proportional  to 
the  current,  and  may  add  to  or  decrease  the  line  volt- 
age. If  the  line  is  long,  the  frequenc}'  high  or  the 
amount  of  power  transmitted  large,  this  induced  volt- 
age will  be  large,  influencing  greatly  the  line  drop. 
By  employment  of  phase  modifiers  the  phase  or  direc- 
tion of  this  induced  voltage  may  be  controlled  so  that 
it  will  be  exerted  in  a  direction  that  will  result  in  the 
desired  sending  end  voltage. 

A  certain  amount  of  self-induction  in  a  transmission 
circuit  is  an  advantage,  allowing  the  voltage  at  the  re- 
ceiving end  to  be  held  constant  under  changes  in  load 
by  means  of  phase  modifiers.  It  may  even  be  made  to 
reduce  the  line  voltage  drop  to  zero,  so  that  the  voltage 
at  the  two  ends  of  the  line  is  the  same  for  all  loads. 
Self-induction  also  reduces  the  amount  of  current 
which  can  flow  in  case  of  short-circuits,  thus  tending  to 
reduce  mechanical  strains  on  the  generator  and  trans- 
former windings,  and  making  it  easier  for  circuit 
breaking  devices  to  function  successfully.  On  the 
ether  hand,  high  self-induction  reduces  the  amount  of 
power  which  may  be  transmitted  over  a  line  and  may, 
in  case  of  lines  of  extreme  length,  make  it  necessary 
to  adopt  a  lower  frequency.  It  also  increases  the  ca- 
pacity of  phase  modifiers  necessary  for  voltage  con- 
trol. High  reactance  also  increases  the  surge  over- 
voltage  that  a  given  disturbance  will  set  up  in  the  sys- 
tem. 

On  the  long  lines,  the  effect  of  the  distributed 
leading  charging  current  flowing  back  through  the  line 
inductance  is  to  cause,  at  light  loads,  a  rise  in  voltage 
from  generating  to  receiving  end.  At  heavy  loads,  the 
lagging  component  in  the  load  is  usually  sufficient  to 
reverse  the  low-load  condition;  so  that  a  drop  in  volt- 
age occurs  from  generating  to  receiving  end.  The 
charging  current  of  the  line  is,  to  a  considerable  extent, 
an  advantage;  for  it  partially  neutralizes  the  lagging 
component  in  the  load,  thus  raising  the  power- factor 
of  the  system  and  reducing  the  capacity  of  synchron- 
ous condensers  necessary  for  voltage  control. 

The  voltage  at  the  receiving  end  of  the  line  should 
be  held  constant  under  all  loads.  To  partially  meet 
this  condition,  the  voltage  of  the  generators  could  be 
varied  to  a  small  extent.  On  the  longer  lines,  how- 
ever, the  voltage  range  required  of  the  generators 
,.  .   "-4    be    too    great    to    permit    regulation    in    this 


manner.  In  such  cases,  phase  modifiers  operating  in 
parallel  with  the  load  are  employed.  The  function  of 
phase  modifiers  is  to  rotate  the  phase  of  the  current  at 
the  receiving  end  of  the  line  so  that  the  self-induced 
voltage  of  the  line  (always  displaced  90  degrees  from 
the  current)  swings  around  in  the  direction  which  will 
result  in  the  desired  line  drop.  In  some  cases  a  phase 
modifier  is  employed  which  has  sufficient  capacit}'  not 
only  to  neutralize  the  lagging  component  at  full  load, 
but,  in  addition,  to  draw  sufficient  leading  current  from 
the  circuit  to  compensate  entirely  for  the  ohmic  and  re- 
actance voltage  drops  of  the  circuit.  In  this  case,  the 
voltage  at  the  two  ends  of  the  line  may  be  held  the 
same  for  all  loads.  This  is  usually  accomplished  by 
employing  an  automatic  voltage  regulator  which  oper- 
ates on  the  exciter  fields  of  the  phase  modifier.  The 
voltage  regulator  may,  if  desired,  be  arranged  to  com- 
pound the  substation  bus  voltage  with  increasing  load. 

CHECKING  THE  WORK 

A  most  desirable  method  of  determining  line  per- 
formance is  by  means  of  a  drawing  board  and  an  en- 
gineer's scale.  A  vector  diagram  of  the  circuit  under 
investigation,  with  all  quantities  drawn  to  scale,  greatly 
simplifies  the  problem.  Each  quantity  is  thus  repre- 
sented in  its  true  relative  proportion,  so  that  the  re- 
sult of  a  change  in  magnitude  of  any  of  the  quanti- 
ties may  readily  be  visualized.  Graphical  solutions 
are  more  readily  performed,  and  with  less  likelihood 
of  serious  error  than  are  mathematical  solutions.  The 
accuracy  attainable  when  vector  diagrams  are  drawn 
20  to  25  inches  long  and  accurate  triangles,  T  squares, 
straight  edges  and  protractors  are  employed  is  well 
within  practical  requirements.  Even  the  so-termed 
"complete  solution"  may  be  performed,  graphically 
with  ease  and  accuracy.  A  very  desirable  virtue  of 
the  graphical  solution  which  follows  is  that  it  exactly 
parallels  the  fundamental,  mathematical  solution.  For 
this  reason  this  graphical  solution  is  most  helpful  even 
when  the  fundamental  mathematical  solution  is  used, 
for  it  furnishes  a  simple  check  against  serious  errors. 
The  result  may  be  checked  graphically  after  each  in- 
dividual mathematical  operation  by  drawing  a  vector 
in  the  diagram  paralleling  the  mathematical  operation. 
Thus,  any  serious  error  in  the  mathematical  solution 
may  be  detected  as  soon  as  made.* 

*A  method  of  checking  arithmetical  operations  which 
requires  little  time  and  is  an  almost  sure  preventative  of  errors 
is  that  known  as  "casting  out  the  nines."  This  method  i.=  given 
in  most  older  arithmetics  but  has  been  dropped  from  many  of 
the  modern  ones.  A  complete  discussion  is  given  in  Robinson's 
'New  Practical  Arithmetic"  published  by  The  American  Book 
Company. 


December,  1921 


THE   ELECTRIC  JOURNAL 


543 


When  converting  a  complex  quantity  mathematic- 
ally from  polar  to  rectangular  co-ordinates,  or  vice 
versa,  the  results  may  readily  be  checked  by  tracing 
the  complex  quantity  on  cross-section  paper  and 
measuring  the  ordinates  and  polar  angle,  or  for  ap- 
proximate work  the  conversion  may  be  made  graphic- 
ally to  a  large  scale.  For  instance,  in  using  hyperbolic 
functions,  polar  values  will.be  required  for  obtaining 
powers  and  roots  of  the  complex  quantity.  For 
approximate  work  much  time  will  be  saved  by  ob- 
taining the  polar  values  graphically. 

In  the  graphical  solution  of  line  performance  it 
will  usually  be  desirable  to  check  the  line  loss  by  a 
mathematical  solution  in  cases  which  require  exact  loss 
values.  Since  the  line  loss  may  be  five  percent  or  less 
of  the  energy  transmitted,  a  small  error  in  the  overall 
results  might  correspond  to  a  large  error  in  the  value 
of  the  line  loss. 

EFFECT  OF  TRANSFORMERS   IN   THE   CIRCUIT 

Usually  long  transmission  circuits  have  trans- 
formers installed  at  both  ends  of  the  circuit  and  one 
or  more  phase  modifiers  in  parallel  with  the  load. 
Such  a  transmission  circuit  must  transmit  the  power 
loss  of  the  phase  modifiers  and  of  the  receiver  trans- 
formers. In  addition  to  this  power  loss,  a  lagging  re- 
active current  is  required  to  magnetize  the  transformer 
iron.  A  complete  solution  of  such  a  composite  cir- 
cuit (generator  to  load)  requires  that  the  losses  of  the 
phase  modifiers  and  transformers  be  added  vectorially 
tc  the  load  at  the  point  where  they  occur  so  that  their 
complete  effect  may  be  included  in  the  calculation  of 
the  performance  of  the  circuit.  A  complete  solution 
also  requires  that  three  separate  solutions  be  made  for 
such  a  circuit.*  First  with  the  known  or  assumed  con- 
ditions at  the  load  side  of  the  lowering  transformers 
the  corresponding  electrical  conditions  at  the  high  volt- 
age side  of  the  transformers  is  determined  by  the  usual 
short  line  impedance  methods.  With  the  electrical 
conditions  at  the  receiving  end  of  the  high-tension  line 
thus  determined,  the  electrical  conditions  at  the  send- 
ing end  of  the  line  are  determined  by  one  of  the  vari- 
ous methods  which  take  into  account  the  distributed 
quantities  of  the  circuit.  With  the  electrical  condition 
at  the  sending  end  thus  determined  the  electrical  con- 
ditions at  the  generating  side  of  the  raising  transform- 
ers are  determined.  The  above  complete  method  of 
procedure,  is  tedious  if  carried  out  mathematically, 
but  if  carried  out  graphically  is  comparatively  simple. 
It  is  the  general  practice  to  neglect  the  effect  of 
condenser  and  lowering  transformer  loss  in  traveling 
over  the  line,  but  to  add  this  loss  to  the  loss  in  the 
high-tension  line  after  the  performance  has  been  calcu- 
lated. If  the  loss  in  condensers  and  lowering  trans- 
formers is  five  percent  of  the  power  transmitted  the 

*A  method  for  calculating  a  transmission  line  with  trans- 
lormers  at  each  end  in  one  solution  is  given  in  the  articles  by 
Messers.  Evans  and  Sels  in  the  Journ.\l  for  Jul.v,  August,  Sept- 
ember, (•/  scq.  1921. 


error  in  the  calculated  results  would  probably  be  less 
than  0.5  percent,  a  rather  small  amount. 

In  order  to  simplify  calculations,  it  is  the  general 
practice  to  consider  the  lumped  transformer  impedance 
as  though  it  were  distributed  line  impedance  by  add- 
ing it  to  the  linear  constants  of  the  line  and  then  pro- 
ceeding with  the  calculations  as  though  there  were  no 
transformers  in  the  circuit.  This  simplifies  the  solu- 
tion but  at  the  expense  of  accuracy,  particularly  if  the 
line  is  very  long,  the  frequency  high  or  the  ratio  trans- 
former to  line  impedance  high.  This  siinplified  solu- 
tion introduces  maximum  errors  of  less  than  two  per- 
cent in  the  results  for  a  225  mile,  60-cycle  line. 

It  has  been  quite  general  practice  to  disregard  the 
eft'ect  of  the  magnetizing  current  consumed  by  trans- 
formers. The  magnetizing  current  required  to  excite 
transformers  containing  the  older  transformer  iron  was 
about  two  percent  and  therefore  its  effect  could 
generally  be  ignored.  Later  designs  of  transformers 
employ  silicon  steel,  and  their  exciting  current  varies 
from  about  20  percent  for  the  smaller  of  distribu- 
tion type  transformers,  to  about  12  percent  on  trans- 
formers of  100  kv-a  capacity  and  about  five  percent  for 
the  very  largest  capacity  transformers.  The  average 
inagnetizing  current  for  power  transformers  is  between 
six  and  eight  percent.  This  inagnetizing  current  is  im- 
portant for  the  reason  that  it  is  practically  in  opposition 
to  the  current  of  over-excited  phase  modifiers  used  to 
vary  the  power-factor.  If  in  a  line  having  100  000 
kv-a  transformer  capacity  at  the  receiving  end,  the 
magnetizing  current  is  five  percent,  there  will  be  a 
5000  kv-a  lagging  component.  If  the  capacity  of 
phase  modifiers  required  to  maintain  the  proper  volt- 
age drop  under  this  load  is  50000  kv-a  the  lagging 
magnetizing  component  of  5000  kv-a  will  subtract  this 
amount  from  the  effective  rating  of  the  phase  modi- 
fiers, with  a  resulting  error  of  ten  percent  in  the  ca- 
pacity of  the  phase  modifiers  required. 

In  the  diagrams  and  calculations  which  follow,  the 
transformer  leakage,  consisting  of  an  in-phase  com- 
ponent of  current  (iron  loss)  and  a  reactive  lagging 
component  of  current  (magnetizing  current),  is  con- 
sidered as  taking  place  at  the  low-tension  side  of  the 
transformers.  A  more  nearly  correct  location  would 
be  to  consider  the  leak  as  at  the  middle  of  the  trans- 
former, that  is,  to  place  half  the  transformer  imped- 
ance on  each  side  of  the  leak.  To  solve  such  a  solu- 
tion it  would  be  necessary  to  solve  two  cotnplete  im- 
pedance diagrams  for  the  transformers  at  each  end  of 
the  circuit.  The  gain  in  accuracy  of  results  would 
not,  for  power  transmission  lines,  warrant  the  in- 
creased arithmetical  work  and  complication  necessary. 
In  the  case  of  lowering  transformers,  it  would 
seem  that  the  magnetizing  current  would  be  supplied 
principally  from  synchronous  machines  connected  to 
the  load.  If  phase  modifiers  are  located  near  the 
lowering  transformers,  the  transformers  would  prob- 
ably   draw    most    of    their    magnetizing    current    from 


544 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


them  rather  than  from  the  generators  at  the  distant 
end  of  the  line.  Partly  for  this  reason,  but  more 
particularly  for  simplicity,  the  leak  of  the  lowering 
transformers  will  be  considered  as  taking  place  at  the 
load  side  of  the  transformers.     On  this  basis  we  first 


current  also  from  the  low  side;  that  is  from  the  gen- 
erators. Both  the  complete  and  the  approximate 
methods  of  solving  long  line  problems  which  follow, 
include  the  effect  of  not  only  the  magnetizing  current 
consumed  by  the  transformers,  but  also  the  losses  in 


TABLE  V— COMPARISON  OF  RESULTS  AS  OBTAINED  BY  FIVE  DIFFERENT  METHODS  OF  CALCULATIONS 


76.000  KW 

(88.S3B 

KVAA 

LENGTH  OF  TRANSMISSIC 

RECEIVER  VOLTAGE  HELD  CONSTANT  AT  220  KV     60  000  KVA 
N  226  MILES     ALL  TABULATED  VALUES  REFERRED  TO  NEUTRAL 

CONDENSER  A 

r  RECEIVING  END 

CIRCULAR 

RECEIVING  END  TO  NEUTRAL 

SENDING  END  TO  NEUTRAL 

LOSSES  IN  KW  TO  NEUTRAL 

LOW  TENSION  SIDE  OF 
TRANSFORMERS 

mOH  TENSION  SIDE  OF 
TRANSFORMERS 

HIGH  TENSION  SIDE  OF 
TRANSFORMERS 

LOW  TENSION  SIDE  OF 
TRANSFORMERS 

TRANSFORMERS 

CONDENSER 

HIGH         1        RAISING 
TENSION  LINE^RANSFORMERS 

TOTAL  LOSS 

VOLTS 

Eln 

Il*Ic 

LEAD 

Ern 

AMPS 

PFr 

VOLTAGE 

CURRENT 

Pl^s 

VOLTAGE 

CURRENT 

PlbEN 

LEAD 

IRON 

COPPER 

KW,, 

%or 

IRON 

COPPER 

KW„ 

*or 

^SN 

% 

Is 

% 

Eqen-N 

% 

'qen 

% 

tojooo 

e 

/J7010 

".."' 

IZ7  SSt 

J0<? 

9963 

;a'  l!° 

'°«3 

iUi 

;^9 

IIII 

'S6  920 

~9i-7 

UH 

IOO_ 

fTTT 

'" 

/30 

lit. 

is3 

23i 

;;! 

zLotl 

/?■*   iS7 

g 

" 

/3i7»3 

«8^ 

^'87 

/«« 

9j^ 

,27.537 

T^s 

22-».4 

Wa 

9iS7 

ii^ 

' 

7/JiOO 

% 

,X7SSi 

JO-lf 

99i3 

'ill'/, 

9«2 

§?fi 

103.9 

«o? 

llSitS 

'•?f2 

2~33~/ 

/osTs 

?7  3« 
91.93 

;55| 

Ws 

■• 

'>3 

2777 

«  8o 

t33  ^09 

i 

= 

iii.; 

too^ 

,7t  2?2 

/■SFJ 

f?SA 

99i 

9rr7 

/I?! 

i.o? 

T,S0„O 

B 

101.1 

996.3 

/S7  I9i 

'°°2 

ilio 

Toli 

Is?< 

il-f  909 

1?2 

2274 

r^7 

97  SI 
9f.SI> 

<:?t 

l«'7 

f 

9SJ, 

!OOJ 

'""' 

,oos 

22^8 

W3 

9TTS 

lit' 

X'so 

9S1000 

B 

117  SSi 

20«f 

9  9*3 

I'fi" 

'jI, 

Isl^ 

'l%%9 

'23  7*0 

Jfi 

~f, 

loa_ 

96  99 
9-f  Sf 

IS" 

*l\ 

liS'3 

iinte 

£■ 

■• 

113  737 

9t  1 

''—' 

/OOJ 

«»_. 

,2^3« 

,-0-^6 

7iT3 

99~i 

9S3I 

•       ■ 

9>9 

/«3: 

?l? 

*A — Transformer  impedances  treated  as  lumped  at  the  ends  of  the  line.  This  is  the  most  nearly  accurate  of  the  five  methods. 
It  is  referred  to  in  the  text  as  the  complete  solution. 

B — This  assumes  the  impedance  of  the  lowering  transformers  as  line  impedance.  It  takes  no  account  of  the  leakage  of  the 
lowering  transformers. 

C — This  assumes  the  impedance  of  both  lowering  and  raising  transformers  as  line  impedance — It  takes  no  account  of  the  leak- 
age of  the  lowering  and  raising  transformers. 

D— This  is  the  same  as  B  except  that  the  leakage  of  the  lowering  transformers  has  been  added  to  the  load— It  is  referred  to 
in  the  text  as  the  approximate  solution. 

E — This  is  the  same  as  C  except  that  the  leakage  of  the  lowering  transformers  has  been  added  to  the  load. 


have  a  load  current  expressed  in  rectangular  co- 
ordinates with  the  load  voltage  as  a  temporary  vector 
of  reference.  To  this  we  add  algebraically  a  phase 
modifier  current  (loss  +  j  or  leading)  and  to  this  we 
add  the  transformer  leakage  (loss  —  j  or  lagging).  In 
other  words,  these  three  components  of  current  at  the 
leceiving  end  of  the  line  add  up  algebraically  upon  a 


transformers  and  phase  modifiers  flowing  over  the  line. 
For  the  purpose  of  determining  the  magnitude  of 
errors  in  the  calculated  results  corresponding  to  sim- 
plified methods  of  calculation  where  transformers  are 
required  at  both  ends  of  the  line,  the  calculations  shown 
in  Table  V  were  made.  Five  methods  of  calculations 
were  made   for  each   of   four  sizes  of  cable.     A  con- 


TABLE  W-PERCENTAGE  ERRORS  IN  RESULTS,  AS  DETERMINED  BY  VARIOUS  METHODS  OF  CALCULATION. 
These  methods  do  not  take  complete  account  of  the  effects  of  the  transformers  in  the  circuit 


Method 

At  Generator 
Percent    Error 

At  Sending  End 
Percent    Error 

Line  Loss 
Percent 
Error 

Transformer  Account 

E„n 

Igen 

PFgen 

E, 

I,        PFs 

A 

0 

0 

0 

0 

0          0 

I 

0 

Complete  method— Assumed  for  comparison  as  resulting  in  100 
percent  values. 

B 

-3.7 

+3.9-0.42 

+0.37 

Leak  of  lowering  transformers  ignored.     Impedance  of  lowering 
transformers  assumed  as  line  impedance. 

C 

-1.8 

-f-2.8 

-2.35 

+0.17 

Leaks  of  raising  and  lowering  transformers  ignored.     Impedauce 
of  raising  and  lowering  transformer  assumed  as  line  impedance. 

D 

-1.6+0.4  ,+0.55 

+0.05 

Same  as  B  except  that  the  transformer  leak  has  been  added  to 
the  load. 

E 

-t-0.5 

-0.7 

-1.62 

-     1     

-0.12 

Same  as  C  except   that  the  transformer  leak  has  been   added 
to  the  load. 

common  vector  of  reference,  thus  making  it  very  easy  stant  load,  load  voltage  and  condenser  capacity  were  as- 

to  obtain  the  resulting  load  at  the  receiving  end  of  the  sumed  for  all  calculations  and  the  results  of  these  calcu- 

line  lations  are  tabulated  in  Table  W.  Thus  method  B  which 

The  transformers  at  the  sending  end  of  the  line  does  not  take  any  account  of  the  lowering  transformer 

have   been   considered   as   receiving   their   magnetizing  magnetizing  current  and  assumes  the  transformer  im- 


December,  1921 


THE   ELECTRIC  JOURNAL 


545 


pedance  as  line  impedance,  gives  the  sending  end  volt- 
age too  low  by  3.7  percent  and  the  current  too  high  by 
3.9  percent. 

Table  X  contains  approximate  data  upon  trans- 
formers of  various  capacities  25  and  60  cycles.  Since 
such  data  will  vary  greatly  for  different  voltages  it 
must  be  considered  as  very  approximate  but  may  be 
found  useful  in  the  absence  of  specific  data  for  the 
problem  at  hand. 

Fig.  67  shows  complete  current  and  voltage  dia- 
grams for  both  short  and  long  lines.  The  diagram 
illustrating  short  lines  is  based  upon  the  current  hav- 
ing the  same  value  and  direction  at  all  points  of  the 
circuit.  On  this  basis  the  IR  drops  of  the  line  and  of 
the  raising  and  lowering  transformers  will  be  in  the 
same  direction.  Likewise  their  individual  IX  drops 
will  also  be  in  the  same  direction.  It  is  evident, 
therefore,  that,   for  short  lines  where  the  capacitance 


voltage  circuit  in  order  to  combine  properly  with  the 
linear  constants  of  the  line.  Although  all  calculations 
are  made  in  terms  of  the  high-voltage  circuit  the  re- 
sults may,  if  desired,  be  converted  to  terms  of  the  low 
voltage  circuit,  by  applying  the  ratio  of  transformation. 
The  transformer  impedance  to  neutral  is  one- 
third  the  equivalent  single-phase  value.  The  reason 
for  this  is  that  the  PR  and  PX  for  one  phase  is 
identical  whether  to  neutral  or  between  phases.  Since 
the  current  between  phases  is  equal  to  the  current  to 
neutral  divided  by  V3.  the  square  of  the  phase  current 
would  be  one-third  the  square  of  the  current  to  neu- 
tral ;  therefore,  R  and  X  to  neutral  will  be  one-third  the 
phase  values.  Another  way  of  looking  at  this  is  that 
the  resistance  and  reactance  ohms  vary  with  the  square 
of  the  voltage,  and  since  the  phase  voltage  is  V3  times 
the  voltage  to  neutral,  the  phase  resistance  and  phase 
reactance   would   be   three   times   that   to   neutral.     In 


TABLE  X— APPROXIMATION  OF  RESISTANCE  AND  REACTANCE  VOLTS,  OF  IRON  AND  COPPER  LOSSES 
AND  OF  MAGNETIZING  CURRENT  FOR  TRANSFORMERS  OF  VARIOUS  CAPACITIES 


Capacity 

of 

Transformer 

KV-A 

60  CYCLES  PER  SECOND 

25  CYCLES  PER  SECOND 

Percent 
•Resistance 

Percent 
•Reactance 

Percent    Loss 

Percent 

Magnetizing 

Current 

Percent 
Resistance 

Percent 
Reactance 

Percent  Loss 

Percent 

Magnetizing 

Current 

Iron 

Copper 

Iron 

Copper 

200 
300 
500 

1.5 
1.3 
1.2 

5.5 
5.6 
6.0 

1.4 
1.3 
1.2 

1.5 
1.3 
1.2 

10 
9 
8 

2.6 
2.15 
1.85 

4.0 
4.0 
4.1 

M 
1.0 
1.0 

2.6 
2.15 
1.85 

10 
10 
9 

750 
1000 
1500 

1.1 

o.'d 

6.3 
6.5 

7.0 

1.0 
0.9 
0.8 

1.1 
1.1 

0.9 

8 
7 
6 

1.65 
1.55 
1.4 

4.2 
6.0 
6.2 

0.9 
0.8 
0.8 

1.63 
1.55 
1.4 

9 
8 

8 

2000 
3000 
5000 

0.8 
0.75 

0.65 

7.0 
7.0 
7.0 

0.7 
0.7 
0.6 

0.8 
0.75 
0.65 

6 
6 
6 

1.3 
1.2 
1.1 

6.4 

6.8 
7.2 

0.7 
0.6 
0.5 

1.3 
1.2 
1.1 

8 
7 
7 

7.500 
10000 
15000 

0.6 
0.6 
0.55 

8.0                     0.6 
S.O            \         0.5 
8.5                     0.5 

0.6 
0.6 
0.55 

5 
5 
5 

1.0 
1.0 
0.95 

7.8 
8.0 
8.0 

0.5 

0.5 

•      0.6 

1.0 
1.0 
U.95 

7 
6 
6 

25000 
35000 
50000 

0.5 
0.5 
0.5 

9.0 
9.5 
10.0 

0.6 
0.6 
0.6 

0.5 
0.5 
0.5 

5 
5 
5 

0.9 
0.9 
0.9 

8,0 
9.0 
9.0 

0.6 
0.6 
0.6 

0.9 
0.9 
0.9 

6 
6 
6 

•The  actual  ohms  resistance  and  ohms  reactance  will  vary  as  the  square  of  the  voltage.    The  values  in  above  table  must  be  considered  as  only  roughly 
approximate.    They  will  vary  materially  with  transformers  wound  for  different  voltages 

is  neglible,  the  transformer  impedance  may  be  added      calculating  the  impedance  to  neutral,  the  results  will  be 


directly  to  the  line  impedance,  provided  the  electrical 
characteristics  on  the  high-tension  side  of  the  trans- 
fomiers  are  not  required. 

As  the  line  becomes  longer,  the  current  changes  in 
both  amount  and  direction  from  point  to  point,  as  a  re- 


the  same  whether  star  or  delta  connection  is  used. 

Even  if  the  transformers  at  both  ends  of  the 
transmission  line  are  duplicates  their  impedance  will 
not  be  the  same  if  operated  on  different  taps  of  the 
windings  to  accommodate  different  voltages.     In  such 


suit  of  the  superimposed  distributed  charging  current  cases,  their  impedances  will  vary  as  the  square  of  the 
of  the  line.  The  result  of  this  is  that  the  impedance 
triangles  of  the  line  and  of  lowering  and  raising  trans- 
formers change  in  both  size  and  relative  position ;  so 
that  their  individual  impedances  can  no  longer  be 
added  together  and  considered  as  all  line  impedance, 
without  accepting  an  error  in  the  results  thus  obtained. 
The  complete  diagram  for  long  lines  shown  by  Fig.  67 
will  be  considered  later. 


TRANSFORMER    IMPEDANCE    TO    NEUTRAL* 

Transformer   constants   are    referred   to   the   high 

*The  writer  desires  to  express  his  appreciation  of  helpful 
assistance  and  useful  data  on  transformer  characteristics  receiv- 
ed from  Mr.  J.  F.  Peters. 


voltages.  For  instance,  if  they  are  operated  at  220 
and  230  kv  at  the  receiving  and  sending  end  respec- 
tively, then  their  impedances  will  have  the  relation  of 

220- 

^^  o.Qis.     In  other  words,  if  the  resistance  and 

230- 

reactance  of  the  receiving  end  transformers  is  3.185 
and  39.82  ohms  respectively,  the  sending  end  trans- 
formers will  have  resistances  and  reactances  of  3.481 
and  43.52  ohms  respectively;  provided  transformer 
taps  corresponding  to  this  higher  voltage  are  used. 

The  impedance  in  ohms  of  an  18000  kv-a,  three- 
phase,  or  of  three  6000  kv-a  single-phase  transform- 
ers,  connected   in  a  bank,  may  be  determined  as   fol- 


546 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


lows.     Assume  that  they  are  operated  at  104000  volts 

between  conductors  (60046  to  neutral)   and  that  the 

resistance  voltage  is  1.04  percent  and  reactance  voltage 

is  4.80  percent. 

The  single-phase  values  are : — 

6  000  000 

=  5/. J  amperes 


^1  = 


X,  = 


104  000 
lot 000  X  o  0104 

104000  X  0.04S 


=  fS.y$  ohms  resistance 


S6.^2  ohms  reactance 


The  values  to  neutral  are,  as  stated  above,  one- 
third  of  the  above;  but,  for  the  sake  of  uniformity  in 
determining  values  to  neutral,  should  preferably  be  de- 
termined as  follows : — 
6  (MO  000 


A',„  = 


99.9.?  amperes  to  neutral 

=  6.^5  ohms  resistance  to  neutral 
fS.S /  ohms  reactance  to  neutral 


bo  0/6 
60  046  X  o  0104 

99.92 

60046  X  0.04S0 

99.92 

If  two  or  more  banks  operate  in  parallel,  the  re- 
sulting impedance  Z,  can  be  obtained  by  taking  the  re- 


to  the  same  kv-a  base.  For  instance,  if  a  6000  kv-a 
and  a  3000  kv-a  transformer  each  have  a  resistance  of 
1.04  percent  and  a  reactance  of  4.8  percent,  their  im- 
pedance is  4.91  percent.  Before  combining  the  imped- 
ances, that  of  the  3000  kv-a  unit  should  be  put  in  terms 
of  the  6000  kv-a,  and  the  resultant  would  be: — 


Z,= 


4.91  X  9.c<-' 


=  sjy  percent  at  6000  kva. 


4.91  +  9.S2 
=  0.69  percent  resistance  volts  at  6000  kva, 
—  3 .19  percent  reactance  volts  at  6000  kva. 

If  the  impedance  triangles  of  the  two  banks  to  be 
paralleled  are  considerably  different  (that  is  tlielr  ratio 
of  resistance  to  reactance)  it  will  be  necessary  to  ex- 
press the  impedances  in  complex  form.  We  have  as- 
sumed above  that  the  triangles  are  proportional,  other- 
wise they  would  not  divide  the  load  evenly  at  all 
power-factors.  Solving  the  preceding  problem  for 
the  resultant  impedance  by  complex  notation,  we  get: 

(1.04  +  J4.S)  X   {2.0X  +  J9.6) 


z,= 


{,1.04  ■\-  j 4. 8)  -I-  (^.0.^-1-796) 
—4:1.917  4-  419.068 
3.12  -h  J14.4 


"°|SfsorcScuiF 


j,OLTiS!.iTJlS£S!»lS^i!!2- 


\7^^^^''^''^"^''^^SEn^srn;r--V 

|> 

^J^                   TP.XoR»= 

■- 

^r.'".":"."?"""""!;; 

X^ 

■"■" 

iiiii^H^^ 

FIG.   67 — VKCrOR    Dl.\r.R.\MS    FOR    SHORT    .\N'D   LONG   LINES 


ciprocal  of  the  sum  of  the  reciprocals  of  the  individual 
impedance.     Thus : — 

Z,Zi 


Zr  = 


Z^  4-  Zi 


In  the  above  example  Z^  =  I  1.0^  -\-  4.8^  = 
//.p/  percent  . 

To  parallel  two  banks  containing  transformers 
duplicates  of  the  above,  we  get,  by  the  above  rule,  the 
following  resultant  impedance : — 


Zr  = 


4.91    X    I.QI 


—, =  2.4^  percent 

4.91  +  49/  ^->  ' 

W'hich  is  just  half  the  impedance  of  a  single  bank, 
as  is  evident  without  applying  the  rule. 

Where  two  or  more  banks  are  to  be  operated  in 
parallel  consisting  of  transformers  not  duplicates,  then 
the  above  rule  must  be  applied  to  determine  the  re- 
sultant impedance.  If  the  impedances  are  expressed 
in  percent,  as  is  usual,  then  they  must  be  both  referred 


4S.2S  K'SSV^'SS" 

'4-734  irrj^lial! 

=  3.27  / 77" 46' 29"  ohms 
=  0.69  -H  j 3-/9  ohm' 

Which  checks  with   the  results  determined  above 

on  the  percentage  basis. 

THE  AUXILIARY   CONSTANTS 

The  graphical  construction  for  short  lines  repre- 
sented typically  by  the  Mershon  Chart  is  so  generally 
known  and  understood  that  a  similar  construction 
modified  to  take  into  accurate  account  the  distribution 
effect  of  long  lines  will  readily  be  followed.  Both  the 
short  and  the  long  line  diagrams  are  reproduced  in  Fig. 
68.  From  these  diagrams  it  will  be  seen  how  the 
three  auxiliary  constants  correct  or  modify  the  short 
line  diagram  adapting  it  to  long  line  problems.  The 
two  mathematical  and  three  graphical  methods  of  ob- 
taining  the   auxiliary    constants    are    indicated    at    the 


December,  1921 


THE   ELECTRIC  JOURNAL 


547 


bottom  of  this  figure.  Since  the  auxiliary  constants 
are  functions  of  the  physical  properties  of  the  circuit 
and  of  the  frequency  only,  they  are  entirely  independ- 
ent of  the  voltage  or  the  current.     Having  determined 


E:s-E„(a,.ja2)'lR('',-jb2) 
l,-|„(a,.ia,),E„(c,-,c,) 


(A)»(a 


.)=[-¥*^ 


vS^a 


yV 


ETC 


(B)-{ 


(C)  =  (c,.,c,)  = 


( BY  CONVERGENT  SERIES- SEE  CHART  X 
=  COSH  e   (BY  REAL  HYPERBOLIC  FUNCTIONS-SEE  CHART  XVI) 

=   TANH  61  e  'G'^'^P^^ICAL-SEE  KENNELLY  CORRECTING  FACTOR  CHARTS  XVIIIXIX-XX-X 
,=  COSHe  (GRAPHICAL-SEE  KENNELLY  S  CHART  ATLAS,  HARVAROPRESS) 
-  COSH  e  (ALL  GRAPHICAL  FROM  WILKINSON  S  CHART    A'— SEE  CHART  V) 

yV  -I 

162,880  *  etc  l(by  convergent  series-see  chart  x 

hyperbolic  functions-see  chart  xvii 

graphical-see  kennellys  correcting  factor  charts  xviii .  xix  i 

graphical-see  kennellys  chart  atus.  harvard  press) 

lall  graphical  from  wilkinsons  chart  b'-see  chart  vi) 

yV^. 


/  1  6         120       6,040. 

=  ]y  SINH  0  (BY  REAL  HYPER 


r        VZ     Y^2=      Y^Z^       yV*  1 

'  L'  *  T*T20"  *5040*36288(f  ^"'"^■J'^''^^^'*^^"'^^'^''"^^"'^^"^^^^"*''''' 
i  SINH  e  ( BY  REAL  HYPERBOLIC  FUNCTIONS-SEE  CHART 


f  ai.^r*  "   (GRAPHICAL-SEE  KENNELLYS  CORRECTING  FACTOR  CHARTS  X 
-  SINH  e  (GRAPHICAL-SEE  KENNELLYS  CHART  ATLAS.  HARVARD  PRESS) 


..^w 


L GRAPHICAL  FROM  WILKINSONS  CHART   C  -SEE  CHART  V 


FIG.    68 — HOW    THE    AUXILIARY    CONSTANTS     MODIFY     SHORT    LINE 
DIAGRAMS   ADAPTING  THEM    TO  LONG  LINE  PROBLEMS 

by  any  of  the  five  methods  referred  to,  the  value  for 
the  auxiliary  constants  corresponding  to  a  given  cir- 
cuit, the  remainder  of  the  solution  for  any  receiving 
end  current  or  voltage  is  readily  performed  graphically. 


Constants  a^  and  a^ — If  the  line  is  short  electric- 
ally the  charging  current,  and  consequently  its  effect 
upon  the  voltage  regulation  is  small.  In  such  a  case 
constant  a^  would  be  unity  and  constant  a^  would  be 
zero,  and  the  line  impedance  triangle  would  be  attached 
to  the  end  of  the  vector  ER  representing  the  receiving 
end  voltage,  since  this  vector  also  represents  the  send- 
ing end  voltage  at  zero  load. 

If,  however,  the  circuit  contains  appreciable  ca- 
pacitance, the  e.m.f.  of  self-induction  resulting  from 
the  charging  current  will  result  in  a  lower  voltage  at 
zero  load  at  the  sending  end  than  at  the  receiving  end 
of  the  line.  Obviously,  the  load  impedance  triangle 
must  be  attached  to  the  end  of  the  vector  representing 
the  voltage  at  the  sending  end  of  the  circuit  at  zero 
load.  This  is  the  vector  ER'  of  the  long  line  diagrams 
of  Fig.  68.  In  such  a  circuit  the  effect  of  the  charg- 
ing current  is  sufficiently  great  to  cause  the  shifting  of 
the  point  R  for  a  short  line  to  the  position  R'  for  the 
long  line.  The  constants  a^  and  a,  therefore,  deter- 
mine the  length  and  position  of  the  vector  representing 
the  sending  end  voltage  at  zero  load.  Actually  the 
constant  a^  represents  the  volts  resistance  drop  due  to 
the  charging  current  for  each  volt  at  the  receiving  end 
of  the  circuit.  That  is,  the  line  PR'  equals  approxi- 
mately one-half  the  charging  current  times  the  resist- 
ance R,  taking  into  account,  of  course,  the  distributed 
nature  of  the  circuit.  For  a  short  line,  it  would  be 
sufficiently  accurate  to  assume  that  the  total  charging 
current  flows  through  one-half  the  resistance  of  the 
circuit.  To  make  this  clear,  it  will  be  shown  later 
that,  for  a  220  kv  problem,  the  resistance  per  conduc- 
tor is  i?  =  34-<i5  ohms  and  the  auxiliary  constant  C^  = 
0.001211  mho.  Thus,  this  line  will  take  0.001211  am- 
pere charging  current,  at  zero  load,  for  each  volt  main- 
tained at  the  receiving  end,  and  since  FR'  ^  approxi- 

R 

we  have  FR'  or  a.,  =  0.001211   X 


^  0.020980.     The  exact  value  of  a.,  as  calculated 


by  hyperbolic  functions,  taking  into  account  the  dis- 
tributed nature  of  the  circuit  is  0.020234.  Since  the 
charging  current  is  in  leading  quadrature  with  the 
voltage  £7?,  the  resistance  drop  FR'  due  to  the  charg- 
ing current  is  also  at  right  angles  to  ER. 

The  length  of  the  line  FR  or  (one-aj,  represents 
the  voltage  consmed  by  the  charging  current  flowing 
through  the  inductance  of  the  circuit.  This  may  also 
be  expressed  with  small  error  if  the  circuit  is  not  of 

X 
great  electrical  length  as  /cc  X  — 


conductor    for    the    220    kv 
Therefore,  FR  =  0.001211 


The  reactance  per 

problem    is    178.2    ohms. 

178.2 
X =^  0.107900  and 

Jq2ioo.     The   exact   value 


Oj   ^    I    —  0.107900  =  0.Q92] 

of  Oi  as  calculated  rigorously,  is  0.893955. 

Constants    b^    and    b„ — These    constants    represent 
respectively  the  resistance  and  the  reactance  in  ohms. 


348 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


as  modified  by  the  distributed  nature  of  the  circuit. 
The  values  for  these  constants,  multiplied  by  the  cur- 
rent in  amperes  at  the  receiving  end  of  the  circuit,  give 
the  IR  and  IX  volts  drop  consumed  respectively  by  the 
resistance  and  the  reactance  of  the  circuit.  To  illus- 
trate this,  the  values  of  R  and  X  for  the  220  kv  prob- 
lem are  34.65  ohms  and  178.2  ohms  per  conductor. 
The  distributed  effect  of  the  circuit  modifies  these 
linear  values  of  R  and  X  so  that  their  effective -values 
are  b^  =  32.198  and  ^2  =^  172.094.  ohms.  The  line 
impedance  triangle,  as  modified  to  take  into  exact  ac- 
count the  distributed  nature  of  the  circuit,  is  therefore 
smaller  than  it  would  be  if  the  circuit  were  without 
capacitance. 

Constants  Cj  and  r, — These  constants  represent 
respectively  the  conductance  and  susceptance  in  mhos 
as  modified  by  the  distributed  nature  of  the  circuit. 
The  values  for  these  constants,  multiplied  by  the  volts 
at  the  receiving  end  of  the  circuit,  give  the  current  con- 
sumed respectively  by  the  conductance  and  the  suscep- 
tance of  the  circuit.  To  illustrate,  the  linear  value  of  c„ 
for  the  220  kv  problem  is  0.001211  mho.  The  distribu- 
tion effect  of  the  circuit  modifies  this  linear  value  so 
that  its  effective  value  c,  =  0.001168.  The  value  of  c, 
is  so  small  that  its  effect  is  negligible  for  all  except  for 
long  circuits.  An  exception  to  this  statement  would 
be  that  if  the  line  loss  is  very  small  compared  to  the 
amount  of  power  transmitted  the  percent  error  in  the 
value  of  line  loss  may  be  considerably  increased  if  the 
effect  of  f,  is  not  included  in  the  solution.  If  c^  is 
Ignored,  c„  will  represent  the  charging  current  at  zero 
load  per  volt  at  the  receiving  end.  Thus  c,  multiplied 
by  the  receiving  end  voltage,  gives  the  charging  current 
at  zero  load  for  the  circuit.  For  the  220  kv  problem 
c„  =  0.001168  and  this  multiplied  by  127020,  the  re- 


ceiving end  voltage  to  neutral,  gives  148.36  amperes 
charging  current  per  conductor. 

Referring  to  the  formulas  at  the  top  of  Fig.  68, 
•^r  (Oi  -|-  /  a„)  is  that  part  of  Eg  which  would  have  to 
be  impressed  at  the  sending  end  if  /,  =  o,  or  the  line 
was  freed  at  the  receiving  end  with  E^  steadily  main- 
tained there.  It  may  be  called  "free"  component  of 
Eg*.  Again  I,.  (61  -j-  ;  b„)  is  that  other  part  of  £, 
which  would  have  to  be  impressed  at  the  sending  end," 
if  Er  =  0,  or  the  line  was  short-circuited  at  the  receiv- 
ing end,  with  I^  steadily  maintained  there.  It  may  be 
called  the  "short"  component  of  £s. 

Similarly,  the  term  /r  (a,  -\-  j  a„)  is  the  compon- 
ent of  Is  necessai-y  to  maintain  I^  at  the  receiving  end 
without  any  voltage  there  (£r  =  0) ;  while  £,  (^1  + 
;'  Co)  is  tlie  component  of  /^  necessary  to  maintain  E^ 
at  the  receiving  end  without  any  current  there  (/r  = 
0).  The  reason  that  Cj  is  likely  to  be  negative  in  ordi- 
nary power  lines  is  because  the  complex  hyperbolic 
angle  of  any  good  power  transmission  line  has  a  large 
slope,  being  usually  near  88  degrees.  The  sinh  of  such 
an  angle,  within  the  range  of  line  lengths  and  sizes  of  B 
ordinarily  present,  is  also  near  90  degrees  in  slope. 
Z 


The  surge  impedance  Zo 


\y 


of  such  a  line  is  not 


far  from  being  reactanceless ;  but  it  usually  develops  a 

small  negative  or  condensive  slope.  This  means  that  the 

/ 
surge  admittance   !"„  =  y    usually   develops  a   small 

positive  slope.  Consequently,  C  or  the  product  E^ 
{^\  +  /  <^:)  usually  slightly  exceeds  90  degrees  in 
slope ;  or  r,  becomes  a  small  negative  rectilinear  com- 
ponent. 


*See  paper  by  Houston  and  Kcnnclly  on  "Resonance  in  A. 
C.  Lines"  in  Trans.  A.  I.  E.  E.  April,  1895 


MtJtlit^tls  ©f  Ma-innilc  Testing  (Concl.) 


1 .  SI'OONER 


HIGH   INDUCTIONS 


TO  obtain  normal-induction  and  hysteresis  data 
at  very  high  inductions  requires  special  meth- 
ods, since  the  ordinary  commercial  permeame- 
ters  have,  in  general,  an  upper  limit  of  magnetizing 
force  of  300  to  400  gilberts  per  centimeter,  though  for 
very  short  intervals  some  of  them  may  be  operated 
somewhat  higher.  The  teeth  of  rotating  machines 
sometimes  require  magnetizing  forces  of  thousands  of 
gilberts  per  centimeter  to  produce  the  required  induc- 
tion. Also  for  certain  scientific  work  it  is  often  de- 
sirable to  obtain  data  on  material  at  high  inductions. 

Isthmus  Method — The  best  known  method  for  ob- 
taining high  induction  data  is  the  isthmus  method  in 
one  of  its  various  modifications"^.  If  a  powerful  elec- 
tromagnet with  conical  pole  pieces,  Fig.  21,  is  arranged 


to- take  a  bobbin  shape  sample  b,  with  a  narrow  cylin- 
drical neck  a,  the  neck  may  be  uniformly  magnetized 
to  a  very  high  induction  if  the  pole  pieces  and  bobbin 
are  suitably  shaped.  If  two  concentric  coils  with  the 
same  number  of  turns,  but  one  with  an  appreciably 
larger  diameter  than  the  other,  are  wound  on  the  cen- 
tral cylinder,  we  can  measure  B  and  H.  B  is  measured 
by  connecting  the  inside  coil  to  a  ballistic  galvanometer 
and  removing,  or  better  reversing  the  bobbin  in  the 
pole  pieces.  H  is  measured  by  a  similar  operation 
with  the  two  concentric  coils  connected  in  opposition 
to  the  ballistic  galvanometer.  By  using  a  sufficiently 
strong  electromagnet,  magnetizing  forces  of  many 
thousand  gilberts  per  centimeter  may  be  obtained.  If 
a  ballistic  galvanometer  with  a  sufficiently  long  period 
is  available,  it  is  possible  to  obtain  satisfactory  resul's 


December,  1921 


THE   ELECTRIC   JOURNAL 


549 


by   reversing   the   magnetizing-   current   of   the   electro- 
magnet."-. 

Modified  Isthmus  Method — Campbell  and  Dye*^, 
and  more  recently  the  U.  S.  Bureau  of  Standards^* 
have  used  a  modification  of  the  isthmus  method  for  de- 
termining inductions  for  magnetizing  forces  up  to  a 
few  thousand  gilberts  per  centimeter  .  The  Bureau  of 
Standards  method  is  represented  by  Fig.  22.  A  power- 
ful electromagnet  was  drilled  as  shown  to  take  a  cylin- 
drical sample  0.6  cm.  indiameter.  Outside  of  this  sam- 
ple are  three  concentric  helical  coils  of  fine  wire,  each 
having  the  same  number  of  turns.  B  is  measured  by 
connecting  the  inside  coil  to  a  ballistic  galvanometer 
and  reversing  the  magnetizing  current.  H  is  determined 
by  connecting  the  two  inside  coils  in  series  opposing  to 
the  ballistic  galvanometer,  noting  the  deflection  when 
the  magnetizing  force  is  reversed  and  then  doing  the 
same  with  the  outside  pair.  The  gradient  of  the  mag- 
netizing force  can  then  be  determined  and  extrapolated 
to  the  surface  of  the  sample.  The  hysteresis  data  may 
be  obtained  by  a  procedure  similar  to  that  used  for  the 
Fahy  Simplex  permeameter. 

It  was  found  by  the  Bureau  of  Standards  to  be 
rather  difficult  to  obtain  correct  coercive-force  data 
due  to  the  magnetic  viscosity 
and  retentivity  of  the  yokes 
and  possibly  to  other  causes. 
By  a  modification  of  the 
usual  procedure,  however,  this 
difficulty  was  overcome.  Re- 
ferring to  Fig.  2 ,  if  the  induc- 
tion is  reduced  apparently  to 
zero,  the  actual  induction  i"; 
probably  some  other  value, due 
to  the  above-mentioned  ef- 
fects. The  procedure  adopted 
is  to  bring  B  approximately  to  zero  by  introducing  resis- 
tance into  the  magnetizing  circuit  and  reversing  the 
magnetizing  current  so  that  A5  ==  B^  apparently. 
Then  the  induction  is  rapidly  increased  to  — B^  and 
back  to  Ba-  In  general,  the  galvanometer  will  indicate 
a  residual  deflection.  By  repeating  the  procedure, 
varying  the  added  resistance  in  the  magnetizing  circuit, 
this  residual  deflection  can  be  reduced  to  zero.  Then 
by  repeating  the  procedure  with  the  H  coils  connected 
to  the  galvanometer  the  resulting  deflection  will  be 
2H^.  By  comparison  with  tests  on  the  same  samples 
with  other  types  of  apparatus,  this  procedure  was 
found  to  give  correct  results.  The  Bureau  of  Stan- 
dards method  has  the  advantage  over  the  original 
Ewing  isthmus  method,  in  that  it  uses  simple  cylindri- 
cal rods  instead  of  the  complicated  bobbin  samples. 
For  magnetizing  forces  up  to  several  thousand  gilberts 
per  centimeter  it  should  be  quite  satisfactory. 

Optical  Methods  — By  the  use  of  the  optical 
method  it  is  possible  to  obtain  high  induction  datai\  / 
(intensity  of  magnetization)  is  measured  by  noting  the 
angle  of  rotation  of  the  beam  of  polarized  light  re- 
flected from  the  magnetized  surface  and  B  is  measured 


ELECTROMAGNET  WITH 

CONICAL   POLE   PIECES  AND 

BOBBIN  USED  IN  THE 

ISTHMUS  METHOD 


according  to  the  method  used  by  DuBois,  by  noting 
the  angle  of  rotation  produced  by  the  introduction  of  a 
glass  plate  just  in  front  of  the  magnetized  surface. 
The  angular  rotation  produced  by  the  glass  is  propor- 
tional to  the  lines  of  flux.  If  the  glass  has  been  stan- 
dardized B  is  known.     Then  the  magnetizing  force, — 

H=  IS-4^1 U) 

This  optical  method  is  suitable  only  for  high  inductions 
and  is  not  as  simple  or  direct  as  the  isthmus  method. 
For  a  discussion  of  other  methods  see  Bureau  of  Stan- 
dards, Scientific  Paper  No.  361^^. 

Extrapolation  Methods — Kennelley^^  some  years 
ago  and  others"''  more  recently  have  shown  that  it  is 
possible  to  extrapolate  normal  induction  data  to  high 
values  with  a  considerable  degree  of  accuracy.  As- 
sume a  set  of  normal  induction  data  and  calculate  the 
values  of  the   reluctivity    po  corresponding  to  definite 

H 
values  of  H,  where, —         -— 

Ba  is  the  ferric  induction  as  explained  previously  where 


FIG.    22 — MODIFIED    ISTHMUS    METHOD    AS    USED    BY    THE    U.    S. 
BUREAU    OF    STANDARDS 

Ba  =^  B  —  H.  Now  if  we  plot  p'o  against  H,  Fig.  23, 
we  obtain  the  curve  cde  of  approximately  the  shape 
indicated.  This  curve  is,  in  general,  approximately  a 
straight  line  and  may  be  expressed  by  the  equation— 
p.,  =  (i  -\-  J  If  where  a  is  the  intercept  on  the  p.. 
axis,  and  a  is  the  straight  portion  of  the  curve.  The 
straight  portion  of  the  curve  may  begin  at  50  gilberts 
per  centimeter  or  more  often  not  until  we  go  as  high 
as  200.  For  most  commercial  materials  a  satisfactoiy 
extrapolation  may  be  made  from  points  at,  say  200  and 
400  gilberts  per  centimeter.  It  is  not  safe  to  use  points 
below  200  unless  the  curves  have  been  actually  plotted 
and  found  to  be  straight  below  200. 

Recently  San  ford  and  Cheney"'  have  shown  that 
an  entirely  similar  procedure  may  be  used  for  extra- 
polating I?r  <Tid  //c,  where. — 


550 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


//,„  -  ^,  =  ai  +  ^1 //„.  .  (7) 

//m    -i-   //c   =  "Z-J  +  *2//n.    .  W 

where  //„  =  the  maximum  magnetizing,  forec,  B^  =-- 
the  residual  induction,  H^  =  the  coercive  force,  a^  and 
a.,  =  the  intercepts  on  the  axis  of  ordinates,  tj  and  h^ 
=  the  slopes  of  the  lines.  The  reciprocal  of  tj  gives 
the  saturation  value  for  Bo-  The  reciprocal  of  b^ 
gives  the  saturation  value  of  Br  and  the  reciprocal  of 
b„  gives  the  saturation  for  H^.  Thus  we  see  that  B^ 
i.nd  He  approach  a  saturation  valuation  as  does  Bo 
when  the  magnetizing  force  is  increased.  This  fact 
was  demonstrated  with  the  Bureau  of  Standards  high 
induction  apparatus  previously  described. 

Accurate  extrapolations  can  not  be  made  by  this 
method  on  a  few  specific  materials,  such  as  the  new 
Honda  steels,  unless  we  go  to  magnetizmg  forces  of 
many  hundreds  gilberts  per  centimeter.  With  one  of 
the  Honda  steels  there  is  a  bend  in  the  reluctivity  curve 
at  1500  gilberts  per  centimeter.  Therefore,  m  oroer 
to  determine  the  saturation  value  we  must  obtain  test 
data  above  this  point.  A  bend  in  the  reluctivity  curve 
is  the  result  of  the  presence  of  two  or  more  consti- 
tuents in  the  material  having  different  magnetic  char- 
acteristics. 

HYSTERESIS   LOSS   DETERMINATIONS 

Hysteresis  losses,  aside  from  the  alternating-current 
methods  which  will  be  dis- 
cussed later,  may  be  deter- 
mined in  a  number  of  ways 
as  follows. 

I . — Most  of  the  previ- 
ously described  permeame- 
ters  may  be  used  for  ob- 
taining hysteresis  loops  with 
more  or  less  accuracy . 
From  the  area  of  these 
loops  hysteresis  losses  may  be  calculated. 

2. — Rice  and  McCollum=*  some  years  ago  de- 
scribed a  method  of  obtaining  hysteresis  losses  directly 
by  means  of  a  ballistic  hysteresis  meter.  If  a  dyna- 
mometer wattmeter  is  arranged  with  its  moving  ele- 
ment suspended  like  a  galvanometer  we  have  the  es- 
sentials of  a  ballistic  hysteresis  meter.  If  we  have,  for 
instance,  a  ring  sample  wound  with  a  magnetizing  and 
secondary  winding  and  connect  the  magnetizing  wind- 
ing in  series  with  the  stationary  coils  of  the  hysteresis 
meter,  and  connect  the  sample  secondary  to  the  moving 
coil  of  the  meter  and  then  reverse  the  magnetizing  cur- 
rent, the  ballistic  throw  of  the  moving  coil  will  be  pro- 
portional to  the  hysteresis  loss  in  the  sample. 

3. — Various  types  of  hysteresis  meters  have  been 
developed,  of  which  the  Ewing^^  is  a  typical  form. 
The  test  sample  consists  of  a  rectangular  specimen  5/S 
by  3  inches,  which  is  revolved  between  the  poles  of  a 
permanent  magnet,  the  latter  being  mounted  on  pivots 
and  provided  with  a  pointer.  The  hysteresis  loss  in 
the  sample  produces  a  deflection  of  the  magnet,  the  de- 
flection being  proportional  to  the  hysteresis  loss,  prac- 


EXTR.^P0I-.\T10N     CL'KVK 


tically  independent  of  the  speed  of  rotation,  provided 
the  speed  is  sufficiently  low  so  that  no  appreciable  eddy 
currents  are  produced.  The  apparatus  is  calibrated 
by  means  of  standard  samples  of  known  quality. 

The  Blondel  apparatus  is  similar  in  operation  to 
the  Ewing  except  that  in  this  case  the  magnet  is  rotated 
and  the  deflection  of  the  sample  is  noted. 

In  the  Holden  type  of  apparatus  a  ring  sample  is 
used  with  a  revolving  magnet.  The  sample  is  coii- 
troUed  by  springs  and  is  brought  back  to  its  initial  posi- 
tion by  means  of  a  torsion  head. 

The  permeameter  methods  of  obtaining  hysteresis 
losses  are  accurate  if  the  permeameters  are  accurate, 
:.s  discussed  above.  According  to  the  authors  the  bal- 
listic hysteresis  method  when  used  with  ring  samples 
is  accurate,  provided  proper  precautions  arc  iisgd  to 
keep  the  eddy  current  losses  down  to  a  minimum.  The 
hysteresis  meters  of  the  Ewing-Blondel-Holden  types 
are  now  practically  obsolete,  although  they  have  been 
used  considerably  in  the  past.  They  may  have  some 
applications  when  a  comparison  is  required  between 
small  samples  of  similar  material.  In  general,  how- 
ever, hysteresis  loss  is  of  interest  only  for  sheet  mater- 
ial. In  order  to  obtain  a  good  check  on  sheets  it  is  de- 
sirable to  use  a  considerable  quantity  of  material  as  the 
quality  from  one  portion  of  the  sheet  to  another  varies 
aiijireciably.  Moreover,  unless  the  samples  are  an- 
nealed they  must  be  fairly  large  to  eliminate  the  effects 
of  shearing  or  punching.  Also  changes  of  permeabili- 
ty of  the  sample  will  make  the  value  of  the  induction 
uncertain  in  the  Ewing-Blondel  and  Holden  types  of 
hysteresis  meters.  Due  to  these  limitations  the  alternat- 
ing-current methods  of  obtaining  losses  on  sheets  have 
superseded  the  other  methods  for  most  commercial 
work. 

CALCUL.'VTIONS  OF   HYSTERESIS  LOSSES  FROM    LOOPS 

If  a  hysteresis  loop  is  plotted  with  B  expressed  in 

gausses  and  H  in  gilberts   per   centimeter   or   gausses, 

the  hysteresis  loss  is  obtained  as  follows : — 

A'  A  ,  , 

»h  =-7v (y^ 

Where  W^  =  the  hysteresis  loss  in  ergs  per  cubic  cen- 
timeter per  circle,  K  =  B  yC  H  ior  unit  area.  A  = 
area  of  loop  in  any  convenient  units.  If  ^  is  measured 
in  square  inches  and  B  equals  i  kilogauss  per  inch  and 
H  equals  2  gilberts  per  centimeter  for  one  inch,  then 
A.'  equals  2000.  A  is  ordinarily  measured  by  means  of 
a  planimeter.  When  a  planimeter  is  not  available  or 
greater  speed  is  required  with  less  accuracy  an  approx- 
imate method  may  be  used  for  obtaining  Wi,.  Accord- 
ing to  circular  No.  17  of  the  Bureau  of  Standards, 

K  A  =  4f/oX  /'•„. ('«) 

to  an  accuracy  of  plus  or  minus  15  percent. 

A  more  accurate  formula  is  the  following  for  hy- 
steresis loops  having  a  maximum  B  of  10  kilogausses''". 


U\  = 


2  (Ns"  -  H,') 


//c   X  JO 


('/) 


where  //«'  and  H^'  are  the   two   values   of  H,    corres- 


December,  1921 


THE  ELECTRIC  JOURNAL 


551 


ponding  to  the  two  positive  or  negative  values  of  B  at 
8  kilogausses.  H^"  is  the  numerically  larger  value 
and  //g'  is  subtracted  algebraically.  The  accuracy  is 
usually  better  than  plus  or  minus  5  percent. 

ALTERNATING-CURRENT    METHODS 

If  a  sample  of  magnetic  material  is  subjected  to 
an  alternating  flux  we  have  the  following  losses. 

1 — Hysteresis  loss 

2 — Eddy-current  loss 

3 — Apparent  loss 
For  most  commercial  purposes  it  is  sufficient  10 
test  for  total  core  loss  under  standard  conditions  with- 
out separating  the  hysteresis  and  eddy-current  losse.i. 
However,  when  it  becomes  necessary  there  are  several 
methods  available  for  making  this  separation.  It  is 
customary  in  this  country^^  to  test  electrical  sheet  at 
a  maximum  induction  of  10  kilogausses  and  a  frequen- 
cy of  60  cycles,  the  corresponding  core  loss  being  de- 
noted by  the  symbol  fFioAo-  In  Europe  the  material 
is  usually  tested  at  inductions  of  10  and  15  kilogausses 
at  a  frequency  of  50  cycles. 

Apparent  loss  is  not  as  well  known  or  generally 
used  a  quantity  as  true  loss,  but  it  is  useful  in  trans- 
former design  for  calculating  the  exciting  current. 
It  is  equal  to  the  product  of  the  volts  and  amperes  for 
a  given  induction  and  frequency  for  a  given  weight  of 
core  material  surrounded   by   a   magnetizing   winding. 


FIG.    24 — CONNECTIONS   FOR   CORE  LOSS   TEST   OF   L-\MINATED   STEEL 
RING  SAMPLE 

In  tlie  finished  apparatus .  the  apparent  loss  is  a  func- 
tion not  only  of  the  intrinsic  quality  of  the  material, 
but  the  number  and  size  of  air-gaps  in  the  completed 
apparatus.  Therefore,  apparent  loss  factors  have  to 
be  applied  with  caution. 

Hysteresis    and    eddy-current     losses     may     be     ex- 
pressed by  the  following  well-known  formula, 

;//=  KxfB^  +  K.pr-By    {,2) 

where  /Cj  and  K„  are  constants,  /  is  the  frequency,  and  t 
is  the  thickness  of  laminations.  For  moderate  induction 
X^  1.6  approximately  (Steinmetz  exponent)  and  y= 
2  approximately.  For  commercial  sheet  steel  the  1.6 
law  for  hysteresis  will  hold  approximately  for  ranges 
of  induction  from  i  to  16  kilogausses.  Outside  of  this 
range  the  law  fails  to  express  the  facts  with  any  degree 
of  acucracy.  K^_  is  approximately  inversely  proportional 
to  the  resistivity  of  the  material.  For  a  more  detailed 
discussion  of  the  hysteresis  law  see  Bureau  of  Stan- 
dards Circular  No.  17. 

TYPES  OF  TEST 

Alternating-current  methods  of  obtaining  core  loss 
may  be  classified  as  follows. 
I— Ring  test. 
2 — Epstein 

a— Standard.        b— Dififerential.  c— Substitution. 


3— Lloyd. 

4 — Robinson. 

S — Three  phase  ring  (high  induction). 

6 — High  frequency. 

/ — If  a  ring  sample  of  laminated  steel  be  wound 
with  a  primary  and  secondary  winding,  the  core  loss 
may  be  tested  as  shown  by  Fig.  24.  The  primary  is 
connected  to  a  source  of  alternating  current  through  a 
wattmeter  to  an  autotransformer  T.  The  secondary  is 
connected  to  the  shunt  circuit  of  the  wattmeter  with  a 
voltmeter  V .  A  frequency  meter  F  is  used  to  indicate 
the  frequency  of  the  supply  circuit.  For  these  connec- 
tions V  is  proportional  to  the  maximum  induction  in 
the  sample. 

jg  X  /  X  />  X  n,^ 

^  ~yX/X-\X«X  //-'  (^-^^ 

Where  E  is  the  r.m.s.  volts,  1  is  the  mean  circumfer- 
ence of  the  ring  in  cms.,  D  is  the  density,  /  is  the  form- 
factor,  A''  is  the  number  of  secondary  turns,  n  is  the 
frequency  in  cycles  per  second,  and  W  is  the  weight 
in  grams.  The  wattmeter  gives  the  core  loss  plus  the  in- 
strument losses  in  the  voltmeter  and  the  shunt  circuit 
of  the  wattmeter.  The  use  of  the  secondary  winding 
is  desirable  because  it  eliminates  any  errors  due  to  IR 
drop  or  1-R  losses  in  the  primary. 

The  ring  test  is  subject  to  certain  errors^".  For 
reasonably  accurate  results  it  is  necessary  that  the  in- 
duced voltage  have  practically  a  sine  wave  form-fac- 
tor or  at  least  that  the  form-factor  be  known.     For  a 


FIG.  25 — .\RR.\NGE.MENT  OF  EPSTEIN  SAMPLES  FOR  CORE  LOSS  TEST 

discussion  of  the  effect  of  form-factor  on  iron  losses 
see  Bureau  of  Standards  Scientific  Papers  88^^  and 
106^-.  The  form- factor  may  be  determined  by  using 
a  synchronous  commutator  or  suppressor^^.  The  ring 
sample  is  used  only  in  special  cases  as  it  is  too  diffi- 
cult to  wind  each  sample  and  more  material  is  wasted 
than  for  the  Epstein  test. 

■2-a — The  Epstein  method  is  the  standard  method 
adopted  by  the  American  Society  for  Testing  Ma- 
terials^^  and  is  very  widely  used  in  this  country  and 
abroad.  The  connections  are  the  same  as  for  the  ring 
test  (Fig.  24)  the  only  difference  being  that  tlie  sam- 
ple now  consists  of  four  equal  bundles  or  strips  of 
sheet  material  arranged  in  a  hollow  square  as  shown 
in  Fig.  25.  The  strips  are  50  by  3  cm.  and  weigh  10 
kilograms.  Each  bundle  is  slipped  into  a  solenoid  as 
indicated  by  the  dotted  lines.  The  solenoids  each  have 
two  layers  of  wire.  The  outside  layer  is  used  as  the 
primary  and  the  inside  as  a  secondary.  The  four 
primary  and  secondary  coils  are  connected  in  series. 
Since  there  is  often  a  difference  of  10  or  15  percent 
between  the  losses  of  sheet  material  sheared  parallel 
and  at  right  angles  to  the  direction  of  the  grain^-*,  it  is 
usually  specified  that  one  half  of  the  material  shall  be 
sheared  one  way  and  one  half  the  other.     For  a  de- 


552 


THE   ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


scription  of  the  standard  core  loss  apparatus  as  used 
by  the  Research  Department,  see  a  previous  paper  by 
the  author*'^. 

The  Epstein  apparatus  is  suppHed  from  a  generator 
in  series  with  which  is  connected  a  harmonic  booster 
giving  a  third  harmonic.  By  varying  the  amplitude  of 
the  third  harmonic  the  form-factor  of  the  induced  volt- 
age of  the  Epstein  apparatus  may  be  kept  at  i.ii  as  in- 
dicated by  means  of  a  direct-current  voltmeter  and  sup- 
pressor together  with  an  alternating-current  voltmeter 
connected  to  the  secondary  of  the  Epstein  apparatus. 
This  is  an  expensive  and  complicated  method  and 
should  be  used  only  where  a  primar}-  standard  appara- 
tus is  required  for  standardization  or  special  work.  For 
routine  acceptance  tests  a  sine-wave  generator  may  be 
used  if  obtainable.  If  not,  satisfactory  results  may  be 
obtained  from  the  60  cycle  commercial  supply  by  u;- 
ing  some  compensation  or  differential  arrangement. 

3-b — Siemens  and  Halske  developed  an  arrange- 
ment using  a  standard  sample  and  a  differential  watt- 
meter, one  element  of  which  was  connected  to  the 
standard  Epstein  apparatus  and  the  other  to  an  Epstein 
apparatus  containing  the  unknown  sample.  By  vary- 
ing the  resistance  in  the  potential  circuits  of  the  watt 
meter  the  readings  could  be  brought  to  zero  and  the 
ratio  of  these  resistances  was  the  ratio  of  the  losses  i:i 
the  two  samples.  If  the  standard  and  unknown  sam- 
ples are  of  similar  material  it  is  obvious  that  commer- 
cial changes  of  voltage  or  frequency  will  not  alter  the 
results  appreciably. 

3-c — In  order  to  avoid  the  necessity  of  using  a 
special  differential  wattmeter  a  substitution  methjd 
may  be  used*^.  If  an  Epstein  apparatus  containing  a 
standard  sample  is  connected  to  an  alternaimg-current 
supply  in  the  usual  way  with  a  voltmeter  and  wattme- 
ter, and  the  voltmeter  is  adjusted  until  the  wattmeter 
reads  the  known  loss  in  the  standard  sample,  and  the 
apparatus  is  then  connected  to  another  Epstein  appara- 
tus containing  an  unknown  sample,  with  tfie  voltmeter 
adjusted  to  its  previous  reading,  the  wattmeter  will 
read  directly  the  loss  in  the  unknown  sample,  provided 
no  considerable  changes  in  the  form- factor  or  fre- 
quency have  occurred  between  the  two  readings. 
Moreover,  the  instruments  may  be  considerably  out  of 
calibration  without  appreciably  effecting  the  accuracy 
of  the  results. 

While  the  Epstein  apparatus  is  the  standard,  it  is 
subject  to  slight  errors  due  to  the  type  of  magnetic  cir- 
cuit. The  shape  of  the  circuit  and  the  butt  joints  tend 
to  produce  leakage  and  non-uniform  flux,  thus  intro- 
ducing errors  of  possibly  two  or  three  percent  in  the 
losses.  Also  the  effect  of  shearing  of  the  samples 
produces  quite  appreciable  increased  losses  unless  the 
material  is  annealed  before  testing. 

5 — M.  G.  Lloyd^"  undertook  to  overcome  these 
disadvantages  by  a  modified  Epstein  apparatus.  The 
samples  weigh  only  two  kilograms  and  are  10  by  2 
inches   and   are   placed   on   edge   with   special    formed 


corner  pieces  of  known  magnetic  quality.  This  ar- 
rangement keeps  the  flux  more  nearly  uniform 
throughout  the  sample  and  reduces  the  shearing  effect 
by  using  a  wider  sample. 

The  Epstein  and  the  Lloyd  apparatus  in  general 
require  a  considerable  quantity  of  the  material.  A  five 
kilogram  Epstein  sample  of  silicon  steel  will  cost,  in- 
cluding shearing,  perhaps  a  dollar  or  more.  When 
hundreds  of  samples  per  month  are  tested,  this  may  be  ■ 
an  appreciable  item. 

4 — In  order  to  reduce  the  weight  of  the  sample  re- 
quired Mr.  L.  T.  Robinson  some  years  ago  devised  an 
apparatus  for  determining  the  hysteresis  loss  by  a  low 
frequency  method''",  which  required  a  sample  weighing 
only  about  one  pound.  The  sample  consisted  of  a 
single  bundle  of  strips  10  by  0.5  inches,  placed  in  a 
magnetic  solenoid  supplied  with  current  at  about  10 
cycles.  The  los.ses  were  measured  by  a  sensitive  watt- 
meter and  corrections  made  for  the  small  eddy-current 
losses.  The  flux  was  of  course  not  uniform  but  a  cor- 
rection factor  was  applied  to  take  care  of  this  factor. 
The  apparatus  is  said  to  be  accurate  to  plus  or  minus 
five  percent,  which  is  not  quite  as  good  as  the  Epstein. 

5 — If  an  attempt  is  made  to  use  any  of  the;;e 
methods  to  obtain  results  at  high  inductions  it  is  diffi- 
cult to  obtain  satisfactory  data,  due  chiefly  to  the  fact 
that  the  large  exciting  current  with  its  high  harmonics 
greatly  distorts  the  induced  voltage  wave  due  to  the  in- 
ductance and  resistance  in  the  primary  circuit.  As 
a  consequence  the  form-factor  becomes  quite  different 
from  the  desired  value.  Nicholson^'  attempted  to 
overcome  this  difficulty  partly  at  least  by  using  three 
identical  ring  samples  with  primary,  secondary  and 
tertiary  windings.  The  primary  windings  were  con- 
nected in  5'  to  a  three-phase  source  through  wattmeter 
current  coils.  The  secondary  windings  were  also  con- 
connected  in  }'  to  the  shunt  circuits  of  the  wattmeters. 
The  tertiary  windings  were  connected  in  A  to  a  gen- 
erator giving  a  third  harmonic  current.  Since  the 
third  harmonic  is  chiefly  responsible  for  the  distor- 
tions of  the  induced  voltage,  these  distortions  could  be 
greatly  reduced  b}'  supplying  the  necessary  third  har- 
monic from  a  separate  source.  By  this  means  it  is  pos- 
sible to  obtain  satisfactory  iron  loss  results  up  to  con- 
siderably over  20000  gausses. 

6 — The  above  mentioned  methods  have  dealt  wi'.ii 
moderate  frequency  tests.  In  these  days  of  radio  de- 
velopment it  is  sometimes  desirable  to  obtain  iron-loss 
results  at  radio  frequencies.  It  is  undoubtedly  possi- 
ble to  obtain  satisfactory  results  by  the  use  of  an  elec- 
tro-static wattmeter  and  possibly  by  some  bridge 
method.  A  very  satisfactory,  method,  however,  due  to 
its  simplicity  and  its  reliability  is  to  use  a  ring  sample 
supplied  with  primary  and  secondary  windings  placed 
in  a  calorimeter  and  to  measure  the  losses  by  simple 
calorimeter  methods.  The  inductions  may  be  meas- 
ured by  means  of  an  electro-static  voltmeter  connected 
to  the  secondar\-  winding-'". 


December,  1921 


THE   ELECTRIC  JOURNAL 


553 


Recommendations — Due  to  its  simplicity,  its  re- 
producibility and  almost  universal  adoption,  the  Ep- 
stein apparatus  as  standardized  by  the  A.  S.  T.  M.  is 
probably  the  most  satisfactory  method  to  use  for  ac- 
ceptance tests  for  electrical  sheets.  By  adopting  the 
substitution  method  (2-c)  outlined  above,  simple  com- 
mercial apparatus  may  be  used  and  the  results  will  be 
entirely  satisfactory  for  acceptance  tests.  If,  how- 
ever, research  work  is  to  be  done,  this  simple  apparatus 
will  hardly  suffice,  especially  if  results  at  various  in- 
ductions and  frequencies  are  required.  In  that  case  a 
variable  speed  generator  is  required,  preferably  with  a 
harmonic  booster  and  a  means  of  measuring  the  form- 
factor. 

The  Lloyd  apparatus,  while  used  at  the  Bureau  of 
Standards,  has  not  met  with  wide  favor  elsewhere,  due 
probably  to  the  complication  of  making  corrections  for 
the  corner  pieces. 

The  saving  in  material  by  the  use  of  the  Robinson 
apparatus  is  probably  more  than  offset  by  the  greater 
complication  of  the  apparatus,  decreased  accuracy,  the 
effect  of  shearing  on  the  narrow  samples  and  the  fact 
that  material  from  at  least  two  sheets  of  steel  should  be 
used  to  give  a  good  average  for  the  lot. 

For    experimental    work    at    high    inductions,    the 


FIG.    26 — SEP.\RATIOX    OF    LOSSES 

three-phase  ring  method,  when  used  with  a   sensitive 
pol\"phase  wattmeter,  may  be  recommended. 

For  radio  frequency  work  the  differential  calori- 
meter method  can  be  recommended  as  being  simple 
and  giving  reproducible  reliable  results. 

SEPARATION   OF  LOSSES 

The  hysteresis  and  eddy  current  losses  may  be 
separated  by  the  following  methods^". 

I — Two-frequency  method.  • 

2 — Two- form- factor  method. 

3 — Two-induction  method. 

4 — -A.lternating-current  and  ballistic  method. 
I — The  well-known  two-frequency  method  con- 
sists in  obtaining  alternating-current  core-loss  data  at 
two  or  more  frequencies,  say  30  and  60  cycles  for  in- 
stance, dividing  the  results  for  a  given  induction  by  the 
frequency,  and  plotting  the  watts  per  cycle  against  the 
frequency  (  as  shown  in  Fig.  26).  The  intercept  on 
the  vertical  axis  gives  che  hysteresis  loss  in  Watts  per 
cycle,  as  indicated,  and  the  eddy  current  loss  as  indi- 
cated in  watts  per  cycle  for  60  cycles.  This  method 
may  be  applied  to  rotating  machines,  as  well  as  Epsteni 
and  similar  samples. 

■? — The  two  form-factor  method  consists  in  obtain- 
ing the  core  loss  for  two  different  form-factors  with 
the  average  volts  (and  therefore  the  hysteresis  loss) 
held    constant.      The    difference    in    the    two    losses    is 


equal  to  the  change  in  the  eddy  loss  which,  of  course  i? 
proportional  to  the  square  of  the  r.m.s.  voltages,  thus 
making  it  possible  to  determine  the  eddy  losses. 

J— By  measuring  the  losses  at  two  inductions  and 
assuming  that  the  hysteresis  loss  varies  as  the  1.6  pow- 
er of  the  induction  and  the  eddy  losses  at  the  square,  it 
is  possible  to  determine  U\  and  W^  from  wo  simultan- 
eous equations.  If  one  induction  is  one  half  the  other 
then, 

"'■   -         ^^- (/^) 

4—Ii  desired,  an  alternating-current  test  may  be 
made  on  a  sample,  then  the  hysteresis  loss  determined 
by  a  permeameter  or  some  ballistic  means.  This  hy- 
steresis loss  multiplied  by  the  frequency  of  the  alter- 
nating-current test  gives  the  hysteresis  loss,  from 
which  and  the  total  alternating-current  loss,  the  eddy 
current  loss  may  be  determined. 

The  two  frequency  method  is  the  simplest  and  is 
applicable  to  rotating  machines  and  polyphase  circuits. 
Care  must  be  taken,  however,  to  insure  that  the  form- 
factor  is  the  same  for  the  different  frequencies.  The 
two  forni-factor  method  is  perhaps  the  more  accurate 
where  suitable  means  are  available  for  altering  the 
form-factor.  The  two  induction  method  is  not  as  ac- 
curate as  the  two  previous  methods  since  there  are  of- 
ten quite  appreciable  departures  from  the  1.6  power 
and  square  laws.  The  fourth  method  is  of  u.se  only  in 
special  cases. 
"'Ewing.  138. 

■''B.  O.  Pierce,     Proceedings    American    Academy    of    Arts  & 

■Science.  Vol.  41,  p.  354,  TQop. 
■'Campbell  &  Dye.  Journal  of  I.  E.  E.  Vol.  54,  p.  35,  1915. 
^*\\'.  L.  Cheney.  Magnetic  Testing  of  Straight  Rods  in  Intense 

J^ields.  Bureau  of  ^ita.ndards  Scientific  Paper  Ko.  361 
■'Kcnnelley.  Trans.  A.  I.  E.  E.  Vol.  8,  p.  485,  1891. 
■'].  D.  Ball.  Some  Notes  on  Magnetization  Curves   G  E   Revie-cV 

Jan.  1915,  p.  31. 

='Sanford   and   Cheney.    Variations   of   Residual    hiduction   and 

Coercive    Force    with    Magnetizing    Force.    Bureau  of 

Standards  Scientific  Paper  No.  384 
"'Rice  &   McCollum.   Ballistic   Dynamometer  as   an   Instrument 

for  Testing  Iron.  Physical  Kcvicze—V ol.  29,  p.  132.  1909 
""Ewing.  p.  380. 
'"Kennelley  and  Alger.  Magnetic  Flu.x  Distribution  in  .\nnular 

Steel  Laminae.  Proc.  A.  L  E.  E.  Dec.  1917,  p.  1113. 
"M.  G.  Lloyd.  Effect  of  Wave  Form  upon  the  Iron  Losses  in 

Transformers.   Bureau    of  Standards   Scientific   Paper 

"■'M.  G.  Lloyd.  The  Dependence  of  Hysteresis  upon  Wave  Form. 
Bureau  of  Standards  Scientific  Paper  .\'o.  106. 

"M.  G.  Lloyd  &  J.  S.  Fisher.  Apparatus  for  the  Determination 
of  the  Form  of  a  Wave  of  Magnetic  Flu.x.  Bureau  of 
Standards  Scientific  Paper  No.  87. 

^'Chubb  &  Spooner.  Effect  of  Direction  of  Grain  on  the  Mag- 
netic Properties  of  Silicon  Sheet  Steel.  The  Electric 
JouRN.AL — Vol.  13,  p.  393.  1916. 

'■'Spooner.  Determining  Iron  Losses  of  Sheet  Samples.  Electrical 
World — \'ol.  77,  p.  Qi.  Ian.  8,  1921. 

'"Lloyd  and  Fisher.  The  Testing  of  Transformer  Steel.  Bureau 
of  Standards  Scientific  Paper  A'o.  log. 

''L.  T.  Robinson.  Commercial  Testing  of  Sheet  Iron  for  Hyster- 
esis Loss.  Proc.  A.  L  E.  E.  Vol.  30,  p.  741,  191 1. 

"Nicholson.  Proc.  I.  E.  E.  Vol.  53,  Jan.  1915. 

"Spooner.  High  Frequency  Iron  Losses.  Journal  A.  I.  E.  E. 
.    Sept.  1920,  p.  809. 

"Spooner.  Magnetic  Properties  of  Sheet  Steel.  The  Electric 
Journal.  Vol.  XIV,  p.  90,  March  1917. 


CoMBMialo?  liBTdailoji  ^ajkres 


J.  L.  KVLA.NUFK 

Motor  Engineering  Dept., 
Westinghouse  Electric  &  Mfg.  Company 


COMMUTATOR  insulation  failures  are  very 
annoying  and  aggravating.  In  a  large  plant 
these  troubles  usually  do  not  come  singly.  One 
motor  after  another  may  fail.  When  the  motor  is 
again  placed  in  service  after  being  repaired  the  trouble 
may  occur  again  after  a  period  of  operation  that  is 
entirely  too  short.  Sometimes  there  is  an  epidemic  of 
commutator  trouble.  The  reason  is  that  where  certain 
conditions  exist,  there  will  be  trouble  and,  as  these 
causes  often  extend  to  hundreds  of  motors  in  the  same 
plant,  many  motors  will  be  affected.  There  are  prob- 
ably more  of  these  failures  on  motors  operating  in  or 
ci round  steel  plants  than  on  all  other  applications  com- 
bined. A  failure  in  the  commutator  may  be  the  cause 
of  short-circuits  in  the  armature  winding  which  may 
necessitate  complete  rewinding. 

A  well  built  commutator,  properly  maintained,  will 

give  little  operating  trouble.     Commutator  failures  are 

usually  the  result  of  the  following  general  conditions : — 

I — Carelessness  and  neglect, 

2 — Lack  of  understanding  of  the  principles  underlying  the 

construction  and  operation  of  the  motor, 
3 — Indifference  of  the  operator,  who  is  more  interested  in 

output  than  maintenance  expense, 
4 — Improper  construction  of  rebuilt  commutators. 
Practically  all  commutator  insulation  failures  are 
caused    by    one    or    a    combination    of    the    following 
causes : — 

I — Rough  burrs  on  the  bars  or  clamping  rings. 
2 — Excessive  voltage  between  bars  due  to  turns  being 
cut  out  of  armature,  etc. 

3 — Carbon  dust  or  other  conducting  materials  under  the 
bars. 

4 — Oil  between  the  bars  or  at  the  edge  of  the  bars, 
causing  pitting  which  eventually  burns  through  the  mica  V 
ring. 

5 — Mill  dust,  carbon  dust,  copper  slivers,  moisture  and 
oil  on  the  exposed  parts  of  the  V  rings,  causing  insulation 
failures,  unless  precautions  are  taken  to  protect  them  and 
keep  them  fairly  clean. 

Usually,  the  fundamental  causes  are  due  either  to 
oil  or  to  conducting  dust,  although  there  are  many  con- 
tributing factors.  The  oil  may  have  come  from  the 
bearings,  if  there  are  no  oil  throwers  on  the  shaft,  or  it 
may  have  been  spilled  on  the  commutator  accidentally 
when  oiling  the  bearings,  or  oil  or  some  other  lubricant 
may  have  been  applied  to  the  surface  of  the  commu- 
tator bars  by  the  operator  with  the  object  of  improving 
commutation. 

Mill  dust  or  iron  ore  dust,  or  the  carbon  dust  from 
the  brushes,  if  allowed  to  collect  in  some  pocket  or 
crevice,  bridges  across  the  mica  between  two  bars  and 
causes  failures.  Dust  usually  accumulates  on  the  ex- 
posed insulation  at  the  ends  of  the  bars  and  even  works 
its  way  under  the  bars.  Small  slivers  of  copper  caused 
when  turning  or  machining  the  copper,  or  when  under- 


cutting  the    commutator   mica    segments,    may    be    the 
cause  of  trouble. 

COMMUTATOR   MATERIALS  AND   CONSTRUCTION 

The  kind  of  mica  and  copper  used,  and  especially 
the  dimensions  and  fits  of  these  materials  with  each 
other  have  more  to  do  with  commutator  insulation 
tailures  than  is  generally  realized.  When  it  is  con- 
sidered that  a  variation  of  o.OOi  inch  on  each  mica  strip 
or  on  each  commutator  bar  makes  a  0.031  inch  differ- 
ence in  diameter  for  a  commutator  with  100  bars  and 
may  be  double  that  if  the  variation  occurs  with  both 
the  bars  and  mica,  it  is  evident  that  precautions  are  nec- 
essary to  build  a  good  commutator.  The  copper  bar 
grooves,  the  mica  V-ring,  and  the  V  of  the  iron  b.ush  all 
require  the  same  diameter  at  the  point  of  the  V.  It  is 
also  vital  that  they  have  the  same  degree  of  taper. 
When  these  parts  do  not  fit  perfectly  with  each  other 
and  are  then  clamped  together,  there  will  be  small  cre- 
vices which  may  be  observed  only  by  making  a  very 
careful  examination.  Although  small  to  the  eye,  these 
crevices  will  be  large  enough  to  permit  fine  particles 
of  dust  to  find  their  way  under  the  bars. 

The  copper  from  which  the  bars  are  made  should 
be  hard  drawn  and  not  soft  copper  which  has  been  ma- 
chined to  shape.  Soft  copper  does  not  have  the  good 
wearing  quality  of  hard  copper.  It  is  also  liable  to 
bend  up  at  the  ends  and  allow  small  crevices,  as  well  as 
to  cause  chattering  of  the  brushes. 

The  built  up  mica  should  have  the  best  compound 
and  the  proper  amount  of  it  for  sticking  the  mica 
laminations  together.  Some  compounds  that  are  used 
do  not  stick  the  mica  to  the  bars,  which  will  increase 
the  probability  of  loose  mica. 

The  writer  recently  had  occasion  to  examine  some 
commutators  made  by  a  concern  which  "remakes  com- 
mutators" and  furnishes  parts  for  many  crane  motors 
and  mill  motors.  These  commutators  were  made  with 
the  following  modifications  from  the  original  construc- 
tion. The  mica  segments  were  0.031  inch  thick  in- 
stead of  0.025  inch,  which  would  increase  the  chance  of 
high  mica.  The  compound  used  for  sticking  the  mica 
laminations  together  would  not  stick  to  the  copper  bars. 
Soft  copper  machined  to  shape  was  used  for  the  bars 
instead  of  hard-drawn  copper  punched  with  a  die.  The 
f.iachined  V's  were  not  accurate,  and  one  end  was  1/16 
inch  smaller  in  diameter  at  the  gauge  point  than  it 
should  have  been.  This  shows  the  importance  of  hav- 
ing all  repair  parts  properly  made  from  accurate  draw- 
ings, and  of  having  suitable  dies  and  tools. 

When  assembling  the  commutator,  conduct- 
ing material  may  have  been  deposited  in  the  assembled 


December,   1921 


THE  ELECTRIC  JOURNAL 


555 


bars  or  perhaps  be  partly  buried  in  mica  V-rings. 
When  turning  commutators  there  may  be  small  slivers 
which  have  burred  over.  If  the  commutators  have 
been  undercut,  the  cut  at  the  end  of  the  mica  segment 
may  have  been  pulled  instead  of  cut  clean,  which  makes 
a  frayed  corner. 

EFFECT  OF  COPPER  SLIVERS,   CARBON  DUST,  MILL 
DUST  OR  ORE  DUST 

Heating  of  bars  is  probably  due  to  bridging  over 
the  mica  segments  between  the  bars  by  small  particles 
of  copper,  carbon  or  other  conducting  dust.  This 
trouble  may  occur  on  either  the  front  or  rear  end  of  the 
commutator  or  on  the  parts  under  the  bars.  If  the  rear 
end  of  the  commutator  is  not  fully  protected,  by  pack- 
ing it  solid  with  insulation,  there  will  probably  be  more 
trouble  there  than  on  the  front  end,  because  conducting 
dust  which  settles  on  the  armature,  cannot  be  removed 
from  the  rear  V-ring. 

EFFECT  OF  OIL 

Pitting  between  bars  is  probably  traceable  to  the 
presence  of  oil,  grease,  or  other  lubricant  on  the  com- 
mutator. This  trouble  from  oil  or  lubricants  usually 
affects  the  front  end  only.  If  the  V-rings  become  filled 
v/ith  oil  they  become  soft  and  gummy.  The  capillary  at- 
traction of  the  oil  draws  in  the  carbon  dust  from  the 
brushes  and  also  other  conducting  particles.  Although 
oil  itself  is  a  good  insulator,  it  adds  no  insulating  quali- 
ties between  two  bars  if  there  is  a  particle  of  conduct- 
ing material  bridging  across  the  mica  strip,  even  if  the 
oil  surrounds  the  particle  of  dust.  Oil  has  two  very 
harmful  effects  when  in  or  on  a  commutator.  The  first 
is  that  the  oil  dissolves  the  compound  used  between  the 
mica  splittings.  The  second  is  that  an  arc  breaks  up 
the  oil  into  carbon,  a  gas  and  a  liquid  which  makes  the 
path  more  susceptible  to  a  second  discharge.  This  is 
so  important  that  at  least  one  large  manufacturer  has  a 
metal  plate  prominently  fastened  directly  above  the 
commutator,  stating  "Caution — Use  no  lubricant  on 
commutator". 

VARNISH  ON  COMMUTATORS 

A  smooth,  hard,  glossy,  varnish  surface  on  the  end 
of  the  bars  and  on  the  insulation  which  protects  the 
projecting  part  of  the  mica  V-rings,  gives  excellent  pro- 
tection. However,  care  must  be  taken  in  applying  it, 
for  liquid  varnish  in  the  commutator  where  it  will  not 
dry  is  harmful.  Liquid  varnish  does  not  dissolve  the 
bond  in  the  mica,  but  it  does  act  much  the  same  as  oil 
when  subjected  to  sparking. 


REMEDIES 

/^Obtain  copper  bars,  mica  segments  and  mica 
V-rings  of  the  best  material  and  absolutely  correct  di- 
mensions. Be  sure  the  copper,  the  mica  V,  and  the 
iron  bush  fit  accurately.  If  the  commutators  are  to  be 
undercut,  make  a  clean  cut  at  the  end  of  the  bars  so  as 
not  to  leave  a  frayed  corner  on  the  mica  strip.  Do 
rot  undercut  a  commutator  until  after  it  has  been 
trued  up  by  turning,  as  the  turning  drags  the  copper 
more  or  less. 

2 — Make  sure  that  there  is  no  dirt  in  the  copper  V 
or  on  the  mica  V  when  assembling.  Sandpaper  lightly 
the  part  of  the  mica  V  which  rests  against  the  bars  im- 
mediately before  putting  it  in  place,  so  as  to  remove  any 
particles  of  dirt  that  may  have  accumulated  on  it,  and 
dc  not  lay  it  down  on  anything  that  is  not  absolutely 
clean.  Clean  out  the  copper  V  immediately  before  in- 
serting the  mica  V. 

S — If  the  commutator  is  of  the  solid  neck  type,  the 
rear  end  can  be  effectually  protected  by  filling  the  space 
from  the  mica  V-ring  to  the  bottom  lead  with  insula- 
tion. The  top  should  also  be  protected  by  placing  an 
insulating  hood  over  the  winding  which  extends  over 
the  leads  and  onto  the  commutator  neck. 

4 — If  the  motor  is  totally  enclosed  keep  the  hand- 
hole  covers  on  at  all  times. 

5 — Apply  over  the  projecting  part  of  the  mica  V- 
ring  three  turns  of  surgical  tape  which  has  been  treated 
in  varnish.  Sew  all  three  layers  so  as  to  join  the  start 
and  the  finish.  Apply  about  five  coats  of  varnish. 
Each  coat  of  varnish  must  be  thoroughly  dry  before 
applying  the  next  coat.  A  baking  varnish  is  preferable 
to  an  air  diying  varnish.  Apply  this  same  insulation  to 
die  rear  end  as  well  as  the  front  end  if  the  space  from 
the  mica  V-ring  to  the  bottom  lead  is  not  built  up  solid 
with  other  insulation  in  such  a  manner  as  to  seal  it. 
Apply  this  insulation  so  that  there  will  be  no  pockets 
f'Qrnied  next  to  the  bars,  and  also  at  the  end  of  the 
iinica  V  so  that  nothing  can  enter  between  the  mica 
ring  and  the  iron  bush.  This  will  make  a  smooth, 
hard,  glossy  surface.  Also  apply  five  coats  of  varnish 
to  the  ends  of  the  bars. 

6 — Keep  all  oil,  grease  or  other  lubricant  away 
from  the  commutator. 

7 — Do  not  allow  any  varnish  or  shellac  to  get  into 
the  commutator  under  the  bars  where  it  would  not  dry. 

S — Brush  off  the  dust  from  the  insulation  at  the 
ends  of   the  bars   occasionally. 

Adherence  to  the  above  suggestions  at  all  times 
will  reduce  commutator  insulation  failures  to  a 
minimum. 


556 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


THE 
ELECTRIC 
JOURNAL 


The   purpose    of    thi«    aection    ie    to    present 

accepted  practical  methods  used  by  operating 

companies    throughout    the    country 


The   co-operation   of  all   those   interested    in 

operating  and  maintaining  railway  equipment 

is    invited.      Address   B.    O.    D.    Editor. 


DECEMBER 
1921 


General  Information  on  Grid  Resistance  Design  for  the 

Operating  Man 


Probably  no  one  piece  of  apparatus  is  more  essential  to  the 
successful  operation  of  a  motor  car  or  locomotive  than  the  start- 
ing and  accelerating  resistor.  This  one  item  alone  causes  higher 
maintenance  charges  than  any  other  individual  piece  of  ap- 
pr.ratus. 
THE  NECESSITY  FOR  A  STAETING  AND  ACCELERATING  RE- 
SISTOR 

The  series  motor  used  in  railway  work  is  normally  a  low 
resistance  machine.  Should  it  therefore  be  connected  directly 
to  the  6oo  volt  trolley,  enormous  currents  would  flow  which 
would  be  limited  only  by  the  small  amount  of  motor  resistance 
and  that  of  the  circuit  connections.  This  current  in  addition  to 
the  serious  effects  on  the  mechanical  and  electrical  parts  of  the 
motor,  would  cause  a  very  severe  starting  jolt  on  the  car. 

WHY  THE  CAPACITY  OF  THE  RESISTOR  IS  BASED  ON  CUR- 
RENTS   LARGER    THAN    THE    CONTINUOUS    CAPACITY    RE- 
QUIRED OF  THE  MOTOR 

With  the  various  materials  available  for  the  construction  of 
grid  resistors,  cast  iron  is  chosen  as  the  best  for  flexibility,  ease 
of  manufacture,  and  application  to  a  particular  design.  Casting 
the  material  in  units  makes  it  possible  to  use  a  great  number  of 
combinations  in  the  same  assembly  and  still  maintain  a  structure 
which  is  satisfactory  in  appearance  and  size.  Although  cast  iron 
in  itself  is  bulkv,  it  gives  the  most  resistance  and  radiation  for 
the  same  space 'factor.  Should  it  be  assumed  that  the  capacity 
of  the  resistor  is  to  be  sufficient  to  carry  the  total  current  con- 
tinuously it  would  be  impossible,  in  a  great  many  cases,  to  place 
the  resistor  on  the  car.  This  is  due  to  the  fact  that  with  a  given 
mass,  only  a  definite  amount  of  radiation  can  be  obtained  under 
a  -given  mounting  and  hence  ventilation  conditions. 

In  calculating  the  total  continuous  capacity  required  of  the 
motor  for  a  particular  service  run.  the  time  that  the  power  is  on 
constitutes  a  large  percentage  of  the  total  time.  VVith  the  start- 
ing resistor  the  time  that  the  power  is  on  constitutes  a  small 
percentage  of  the  total  time.  The  average  heating  current  for 
the  resistor  is  therefore  considerably  less  than  that  of  the  motor. 
As  the  capacity  of  a  conductor  is  a  question  of  radiation  and  as 
radiation  is  based  on  surface  e-vposcd  to  air  currents,  the  smaller 
the  average  heating  curent,  the  smaller  would  be  the  conductor 
required.  The  conductor  in  this  case  being  the  grid  resistor,  the 
smaller  the  current  the  smaller  the  total  resistor  will  be.  In  a 
few  words  then,  the  resistor  size  is  kept  down  by  working  a 
small  amount  of  material  very  hard  for  a  short  space  of  time. 

HIGH  SPOTS  IN  THE  DESIGN  OF  A  GRID  RESISTOR 
In  the  design  of  grid  resistors  the  following  elements  enter 
into  and  affect  the  final  result. 

1 — Car  weight,  unloailcd, 

2 — Wheel  diameter.  |    ij^e    motor    curve    as    made    by    thn 

3 — Gear  ratio,  ^  manufacturer    includes    these    items. 

4 — Motor  characteristics, ) 

5 — Average   line    voltage, 

6 — Type  of  control 

7 — Number  of  motors, 

8— Motor  resistance. 
The  two  factors  to  be  considered  are,  resistance  value  and 
capacity.  Taking  them  in  the  order  in  which  they  are  calculated, 
the  resistance  is  determined  by  the  amount  of  current  required, 
on  the  first  notch,  to  give  the  necessary  starting  tractive  effort 
to  start  the  car  as  fast  as  possible  without  undue  discomfort  to 
the  passengers.  Experience  has  shown  that  for  average  city  and 
interurban  ser\'ice  135  to  165  pounds  tractive  effort  per  ton  will 
give  a  good  start. 

As  a  hypothetical  case  we  will  assume  30  tons  as  the  weight 
of  the  car  with  a  starting  tractive  effort  of  140  pounds  per  ton. 
The  total  tractive  effort  required  to  accelerate  the  car  will  be 
4200  pounds.  It  has  already  been  decided  that  the  service  in 
which  this  car  will  operate  requires  four  50  hp,  ventilated 
motors.  The  tractive  effort  required  per  motor  is  therefore  4200 
H-  4  or  1050  pounds.  The  motor  curve  for  the  conditions  involved 
gives  a  current  of  54  amperes. 

If  the  resistance  is  figured  for  this  current,  according  to 
Ohm's  law,  due  to  the  inductance  of  the  motors,  and  the  main 
circuit   connections,   the   current   per   motor   will   not   actually 


reach  54  amperes  until  a  short  interval  after  the  main  circuit  to 
the  motors  has  been  closed.  Therefore,  the  tractive  effort  will 
not  be  sufficient  to  give  the  desired  start.  To  take  care  of  this 
loss  in  tractive  or  starting  effort,  an  inductance  factor  of  0.75 
is  used.  To  obtain  the  proper  current  value  the  above  current  of 
54  amperes  is  divided  by  the  inductance  factor  0.75,  which  gives 
a  current  of  72  amperes. 

With  four  motors  and  series  parallel  control,  the  motors 
will  be  connected  in  two  groups  of  two  motors  in  parallel  with 
the  two  groups  in  series.  The  current  in  the  resistor  for  the  first 
notch  will  therefore  be  2  X  72  or  144  amperes.  Assuming  the 
average  voltage  to  be  550  volts,  the  total  resistance  required  will 
be  550  divided  by  144  or  3.82  ohms.  The  resistance  of  the  motor 
at  75  degrees,  is  O.745  ohm.  The  resistance  of  the  grids  and  the 
connections  between  the  motor  and  the  trolley  should  be  the 
difference  between  3.82  ohms  and  the  motor  rsistance  or  3.075 
ohms.  An  approximate  method  of  obtaining  the  resistance  value 
is  to  divide  the  average  voltage  by  the  hour  current  rating  of 
the  motor. 

The  next  step  in  the  design  is  to  divide  this  resistance  into 
the  proper  steps  to  obtain  smooth  acceleration.  There  are  various 
methods  of  doing  this  which  are  based  on  empirical  figures 
obtained  from  a  careful  study  of  the  subject  and  the  actual 
design  of  a  great  number  of  resistors.*  These  values,  however, 
vary  to  some  extent,  depending  on  all  the  conditions  involved, 
so  that  in  each  individual  case  there  is  a  certain  amount  pf  cut 
and  try  before  the  final  design  is  completed.  It  is  sufficient, 
therefore,  to  say  that  the  resistance  values  should  be  so  propor- 
tioned as  to  give  a  systematic  progression  in  cutting  out.  On 
motor  cars,  approximately  40  percent  of  the  total  resistance, 
including  that  of  the  motors,  is  cut  out  on  the  second  notch.  On 
locomotives  this  figure  is  considerably  lower,  and  will  vary  to  a 
greater  extent  than  on  motor  cars,  due  to  a  wider  range  of  con- 
ditions. The  remaining  series  notches  are  then  divided  in  pro- 
portionate steps,  keeping  in  mind  that  the  values  in  the  series 
position  will  in  most  cases  be  the  same  as  those  used  in  the 
parallel  position.  Some  manipulation  is  required  in  a  great  many 
cases  to  obtain  the  proper  notching  in  both  the  series  and  the 
parallel  positions. 

CURRENT  CAPACITY  OF  THE  GRID  RESISTOR 
As  stated  above  it  is  not  necessary  to  allow  a  capacity  in 
the  grid  resistance  equivalent  to  the  continuous  capacity  required 
of  the  motor.  A  still  further  reduction  in  capacity  is  possible, 
due  to  the  fact  that  only  a  small  part  of  the  total  resistance  is  in 
circuit  during  the  complete  acceleration.  It  is  therefore  evident 
that  the  capacity  of  any  notch  need  be  only  sufficient  for  the  pro- 
per radiation  of  the  heat  generated  while  that  particular  section 
of  the  resistance  is  in  the  circuit.  The  same  experience  which 
has  taught  the  proper  arrangement  of  the  resistance  steps  also 
teaches  to  allow  the  proper  current  capacities  for  the  various 
notches.  In  the  majority  of  cases,  this  has  proven  to  be  between 
the  values  of  35  percent  minimum  and  85  percent  maximum 
of  the  total  continuous  current.  In  other  words  for  the  first  notch 
we  would  allow  the  lower  figure  and  for  the  last  notch  the 
higher.  The  intermediate  notches  are  divided  proportionately. 
Consideration  should  be  given  however,  to  the  various  combina- 
tions where  the  steps  are  used  in  parallel,  in  which  case  allow- 
ance should  be  made. 

APPLYING   STANDARD   GRIDS   TO   THE   CALCULATED 
DESIGN 

.\s  the  resistance  values  and  the  capacities  of  the  several 
steps  are  known  it  is  only  necessary  to  pick  out  the  proper  grids 
t,i  fit  the  design.  It  will  be  found  that  the  design  must  be  modi- 
fied to  fit  the  resistance  of  the  grids  set  by  the  capacities  re- 
quired. In  some  cases  the  resistance  will  be  increased  and  in 
others  decreased,  so  that  the  total  resistance  will  remain  about 
the  same.  When  choosing  the  poper  capacity  for  the  grid  the 
calculated  capacit>'  required  must  be  the  same  as  that  listed  for 
the  commercial  grid.  The  current  value  listed  is  the  continuous 
c:;pacity  of  the  grid.  Harry  R.  Meyer. 

*See    article    on    "Design    of    D.    C.    Accelerating    Resistors" 
by  L.  J.  Hibbard,  in  the  Journal  for  Oct.,  1916,  p.  508. 


December,  1921 


THE  ELECTRIC  JOURNAL 


557 


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o 


2o6j— Connection  b  run  1'o\vi-:k-F-\ctor 
Meter— Kindly  explain  the  action  of 
a  power-factor  meter,  also  show  a 
diagram  of  the  internal  and  external 
connections   for  three-phase  systems. 

J.  J.  B.  (III.) 
The  power-factor  indicator  is  an  in- 
strument designed  to  give  a  direct  read- 
ing at  anv  instant  of  the  power-factor 
in  a  circuit  or  system  of  circuits,  as  well 
as  to  indicate  whether  the  current  is 
leading  or  lagging.  The  power-factor  of 
a  single-phase  circuit  may  be  calculated 
from  the  reading  of  an  ammeter,  volt- 
meter and  wattmeter.  The  power-factor 
of  a  balanced  three-phase  circuit  can  also 
he  calculated  directly  from  the  readings 
of  two  wattmeters  used  to  measure  the 
power,  knowing  the  voltage  and  current 
in  the  circuit.  A  direct  reading  power- 
factor  indicator,  however,  is  usually  to 
be  preferred  for  station  purposes,  as 
such  a  meter  gives  the  power-factor  dir- 
ectly and  also  indicates  whether  the  cur- 
rent is  leading  or  lagging.  Under  certain 
conditions  it  is  more  convenient  to  obtain 
a  direct  measure  of  reactive  (wattless) 
power  supplied  to  a  circuit ;  only  a  watt- 
meter can  be  used  for  this  purpose.  The 
moving  vane  type  of  power-factor  meter, 
contains  a  movable  soft  iron  vane  which 


ing  field  coils  are  shown  connected  in 
star  lor  three-phase  connection,  ihe 
single  current  coil  C  which  energizes  the  ■ 
moving  vane  has  both  leads  brought  out 
to  the  top  of  the  instrument.  This  dia-- 
gram  gives  a  general  idea  of  the  internal 
connections.  ".  P.  s. 

2063— Z-CONNECTION  OF  CURRENT  TRANS- 
FORMERS—The    system    shown    in    Fig. 
(a)  is  a  three-phase,  four-wire,  4000./ 
^^oo     volt      system      with     grounded 
neutral.  Will  the  Z-connection  of  cur- 
rent transformers  give  absolute  protec- 
tion on  all  phases,  using  only  two  re- 
lays, or  will  it  be  necessary  to  install 
three   relays   and   connect  the   current 
transformers  in  star.   A.  M.  N.  (Ohio.  ) 
Three  current   transformers   arranged 
according  to  the  Z-connection,  together 
with  two  relavs,  give  absolute  protection 
against  overload  on  either  a  three-phase, 
four-wire  system  or  a  three-phase,  three- 
wire  system  with  grounded  neutral.  The 
principal  disadvantage  of  this  scheme  for 


eliminate  all  protective  features,  such  as 
overload  and  no-voltage  release  protec- 
tion and  quick  transfer  from  low  to  high 
voltage.  Some  added  apparatus  would  be 
necessary  to  give  the  overload  and  low- 
voltage  protection.  A  three-pole,  double- 
throw  knife  switch  would  not  be  safe  for 
the  interruption  of  the  energy  of  S50 
volt,  250  hp.  motors.  Hand  operated  oil 


FIG.  Z062 — (a). 


in  the  polyphase  instrument,  is  magneti- 
zed through  a  stationary  coil  carrying  a 
current  in  phase  with  the  current  of  one 
phase  of  the  circuit.  There  is  one  station- 
ary shunt  coil  for  each  phase,  the  ar- 
rangement being  such  as  to  produce  a 
rotating  field.  The  moving  vane  thus 
takes  up  a  position  in  which  the  direction 
of  the  flux  produced  in  it  by  the  current 
coil  when  at  a  maximumis  coincident  with 
the  direction  of  the  resultant  flux  due  to 
the  voltage  coils.  In  the  three-phase  in- 
strument, three  voltage  coils  placed  120 
degrees  apart  are  used;  in  the  two-phase 
meter,  two  voltage  coils  at  90  degrees  are 
used.  In  the  single-phase  type,  the  iron 
vane  is  energized  by  a  stationary  coil 
placed  in  phase  with  the  current  of  the 
line,  while  the  rotating  field  is  produced 
the  same  as  in  the  two-phase  instrument 
by  means  of  only  two  potential  coils  ap- 
proximately 00  degrees  apart;  one  of 
which,  however,  is  connected  to  the  line 
through  a  non-inductive  resistance,  and 
the  other  through  a  reactance.  For  the 
purpose  of  damping  the  instrument  an 
aluminum  disc  operates  in  the  field  of 
two  permanent  magnets.  In  Fig.  (a) 
three  stationary  energizing  coils  or  rotat- 


r^'rn 


— irewswr 

Overload  Relay 


FIG.  2063— (a). 

straight  overload  protection  is  the  some- 
what more  complicated  wiring.  This  may 
be  an  important  factor  when  meters  and 
other  instruments  are  operated  from  the 
same  set  of  current  transformers.  R.  C.  S. 

2064— Starting  Induction  Motors  on  60 
Percent  Voltage— An  installation 
consisting  of  three  200  hp.  5.S0  volt  in- 
duction motors  is  supplied  from  a  bank 
of  transformers  consisting  of  three  l.SO 
kv-a,  single-phase  transformers  con- 
nected delta  on  the  secondary.  In  an 
installation  of  this  kind,  where  all  the 
motors  are  alike  and  consenuently 
having  the  same  starting  qualifies  i.e., 
they  start  on  a  60  percent  tap  or  .•^.so 
volts,  would  it  not  be  feasible  and  also 
practical  to  eliminate  the  autotransfor- 
mer  starting  equipment  for  each  motor 
and  have  taps  brought  out  from  the 
transformer  for  starting?  This  ar- 
rangement would  onlv  require  three- 
pole  double-throw  switches.  Do  trans- 
formers acting  in  this  dual  ranacitv' 
have  to  he  of  special  design?  If  so 
please  explain.  Is  mv  sketch  correct. 

R  H.  N.  L.  (B.  C.) 
The  three  motors  can  be  started  by 
using  low-voltage  taps  on  the  transfor- 
mers which  supplv  the  motors  with 
power.  The  transformers  would  be  of 
snecial  design  in  that  the  windings  would 
have  to  have  one  or  more  special  taps 
brought  out.  If  there  were  frequent  and 
long  heavv  starts,  the  windings  mi"ht 
have  to  have  heavier  bushings.  The 
elimination    of    the    autostarters    would 


FIGS.  2064— (a)  and(b). 

switches  or  magnetic  contactors  would 
be  more  suitable.  The  auto-starters  use 
oil  immersed  switches.  The  scheme  of 
connections  as  shown  in  Fig.  (a)  is  all 
right.  However,  a  better  connection  is 
shown  in  Fig.  (b)  which  requires  that 
onlv  two  of  the  three  transformers  be 
special.  W.  C.  G. 

,06=;— Connections  for  Synchronoscope 
—Kindly  explain  action  of  synchrono- 
scope when  synchronizing  two  alterna- 
tors, also  show  diagram  of  connections 
for  three-phase  •systems. 

J.  J.  B.  (III.) 
The  inductor-type  synchronoscope  as 
shown  in  Fig.  (a)  has  two  windings.  The 
upper  windingis  connected  directly  to  the 
incoming  machine  while  the  lower  wind- 
ing is  connected  to  the  running  machine 
through  a  resistance.  The  running  wind- 
ing consists  of  two  parts,  one  of  which 
is  connected  in  series  with  a  non-induc- 
tive resistance  and  the  other  with  an  in- 
ductive resistance  in  order  to  produce  a 


FIG.  206s  (a). 


rotating  field  necessary  for  the  operating 
elements.  The  pointer  can  rotate  freely 
in  either  direction  and  is  so  arranged 
that  when  the  frequency  of  the  incoming 
machine  is  lower  than  that  of  the  run- 
ning machine  it  rotates  in  the  direction 
indicated  by  slox^'  on  the  dial,  or  if  the 
frequency  of  the  incoming  machine^  is 
higher  than  that  of  the  running  machine 
it  will  rotate  in  the  opposite  direction, 
indicated  by  fast,  on  the  dial.  When  the 
frequencies  of  both  machines  are  the 
same,  the  pointer  will  stop  at  some  posi- 
tion around  the   dial,   depending  on  the 


558 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


angle  by  which  the  voltage  of  the  incom- 
ing machine  is  out  of  phase.  The  instru- 
ment is  so  designed  that  when  the  two 
machines  are  in  synchronism  the  pointer 
will  be  in  a  vertical  position  upward, 
which  is  the  only  position  marked  on  the 
dial.  Thus  the  instrument  indicates  when 
the  frequencies  of  the  two  machines  are 
the  same  and  also  when  they  are  exact- 
ly in  synchronism.  An  excellent  article 
on  "Synchronizing  with  a  Synchrono- 
scope"  by  J.  C.  Group  was  published  in 
the  Journal  for  Dec.  1920  p.  567. 

M.  M.  D. 

2066 — Two-Speed  Motor — Please  explain 
how  the  two  and  four-pole  change  is 
made  on  a  1/6  hp,  single-phase,  60 
cycle,  no  volts,  1700-3400  r.  p.  m. 
motor.  A.  H.  K.  (Calif.') 

The  1/6  hp,  single-phase,  60  cycle,  no 
volt,  1700-3400  r.  p.  m.  motor  is  provided 
with  a  special  main  winding  and  a  start- 
ing winding,  so  that  by  means  of  a  pole 
changing  switch  the  two  speeds  men- 
tioned can  be  obtained.  The  main  wind- 
ing is  wound  with  two  coils  as  in  a  two 


in  Fig.  (a)  in  each  pole  indicate  the  two 
coils  which  are  wound  in  parallel  as  men- 
tioned above.  The  operation  of  the  motor 
as  a  two-pole  or  four-pole  motor  is  the 
same  as  any  series  and  consequent  pole 
arrangement.  The  starting  winding,  how- 
ever, functions  along  slightly  different 
lines  and  an  analysis  of  the  flux  from 
the  various  starting  winding  coils  for  the 
two  connections  of  the  switch  will  indi- 
cate that  its  operation  is  the  same  as  a 
two-pole  motor  with  one  coil  missing  in 
the  one  case  and  a  four-pole  motor  with 
two  coils  missing  in  the  other  case, 
c.  A.  M.  w. 

2067 — Short  Circuited  Coil — In  a  five 
hp,  three-phase,  60  cycle,  220  volt,  1750 
r.  p.  m.  induction  motor,  star  con- 
nected, we  have  a  coil  which  I  think  is 
.short-circuited  within  itself  because  I 
disconnected  the  particular  coil  and 
there  is  no  ground  or  short-circuit 
with  another  coil,  making  the  test  with 
a  test  lamp.  So  I  cut  out  that  coil  and 
tried  the  motor  but  it  still  gets  hot  on 
that  particular  coil.   I   then   short-cir- 


FIGS.  2066 — (a)  and  (b). 


pole  motor  except  there  are  Ivo  wires  in 
parallel  and  eight  leads  are  lirought  out 
for  connection  to  the  pole  changing 
switch,  as  shown  in  Fig.  (a).  The  start- 
ing winding  consists  of  one  coil  with 
two-pole  pitch  or  throw  and  two  coils 
with  four-pole  pitch  or  throw,  six  leads 
being  brought  out  from  these  three  coils 
for  connection  to  the  pole  changing 
switch,  as  in  Fig.  (a).  The  leads  from 
the  main  and  starting  windings  are  con- 
nected to  the  pole  changing  switch  as 
per  Fig.  (b).  With  the  motor  leads  at 
the  left  of  the  pole  changing  switch  in 
Fig.  (b)  numbered  from  top  to 
bottom,  connecting  lead  I  to  one  side  of 
the  line  and  lead  t,  to  the  other  gives  the 
four-pole  connection  or  the  consequent 
pole  arrangement.  By  connecting  leads  2 
and  4  across  the  line  the  two  pole  con- 
nection will  be  obtained.  The  pole  chang- 
ing switch  is  so  arranged  that  the  start- 
ing winding  is  connected  across  the  line 
with  the  switch  in  either  the  two  or  four 
pole  position.  The  two  solid  outside  coils 


cuitcd  the  two  ends  of  the  coil  and  it 
heats  just  the  same.  It  seems  to  heat  up 
with  it  in  circuit  or  out  of  circuit  and 
I  have  not  been  able  to  locate  the 
trouble.  H.  i.  I.   (Hawaii) 

This  short-circuited  coil  is  cutting  the 
primary  flux  just  the  same  as  any  of  the 
other  coils,  and  acts  as  tlu  short-circuited 
secondary  of  a  transformer,  with  the 
other  motor  coils  acting  as  the  primary.lt 
is  necessarj'  to  clear  the  short-circuit  in 
this  coil,  either  by  opening  all  the  turns, 
preferably  at  the  hack  end  of  the  coil 
and  carefully  insulating  the  ends  of  each 
turn,  or  else  by  removing  this  coil  com- 
pletely. The  motor  will  never  operate  sat- 
isfactorily as  long  as  there  is  a  short- 
circuited  coil  where  it  can  cut  the  motor 
flux,  even  though  this  coil  be  electrically 
disconnected  from  the  circuit.  C.  R.  R. 

2068— Voltage  Drop  Across  Reactance 
AND  Resistance — Kindly  explain  the 
following  phenomena.  Fig.  (a)  shows 
the  connections  of  a  bake  oven  I  con- 


structed. As  it  is  used  on  alternating- 
current,  I  made  a  reactance  coil  with 
taps  at  different  points  in  the  winding 
to  regulate  the  heat.  This  coil  has  a 
closed  magnetic  core.  Fa.  Kb,  and  Ku. 
were  made  by  one  and  the  same  volt- 
meter, the  meter  being  moved  to  these 
different  positions  to  get  the  various 
readings. 


React- 

s'witch 
in  posi- 
tion 

Amps. 

Va 

Reac. 

Vc 
Res. 

Total 
Vb  &  Vc 

: 

1-5 

105 

'  ss 

17 

"5 

2 

2->5 

105 

93 

.36 

3 

3.' 

105 

83 

.W 

138 

4 

4.05 

105 

6S 

7< 

139 

5 

5.0 

105 

43 

80 

132 

6 

6.0 

104 

104 

104 

Now,  the  question  is,  why  is  the  sum 
of  Vb  and  Vc  higher  than  the  voltage 
Fa  accross  the  line?  Can  this  oven  re- 
sistance act  like  a  condenser? 

N.  J.  v.  (Cal.) 

Your  oven  resistance  does  not  act 
like  a  condenser.  The  sum  of  the  volt- 
ages measured  by  the  voltmeter  at  points 
B  and  C  is  greater  than  the  voltage 
across  the  line  measured  by  voltmeter  at 
A  because  the  line  voltage  is  not  the 
arithmetical    sum  of  the  two  voltages  but 


KccuUtinc  B«*c»i 


FIGS.  2068 — (a)  and  (b). 


is  the  vector  sum  oi  the  voltage  drop 
across  the  resistance  and  reactance  coils, 
as  shown  with  solid  lines  in  the  vector 
diagram  for  position  5  Fig.  (b).  If  the 
resistance  was  wound  non-inductively 
and  the  reactance  coil  was  without  re- 
sistance then  the  vector  RI  or  drop 
across  the  resistance  would  be  exactly^po 
degrees  out  of  phase  with  the  XI  vector 
representing  reactance  drop.  Since  there 
is  considerable  resistance  in  the  react- 
ance coil  and  a  certain  reactance  drop 
across  the  inductively  wound  resistance 
the  vectors  A7  and  RI  are  not  exactly  90 
degrees  out  of  phase.  The  rectors  repre- 
senting Fa,  Fb  and  Vc,  in  Fig.  (b),  are 
shown  dotted  for  reactance  switch  in 
position  I.  M.  M.  B. 

2069— Special  Insulation  for  Motors — 
I  believe  it  is  customary  to  furnish 
special  insulation  on  motors  for 
Panama,  India  and  other  tropical 
countries  in  order  to  make  these 
motors  serviceable  under  extreme  heat 
and  moisture  conditions.  Kindly  advise 
what  this  special  insulation  would  con- 
sist of  in  case  of  a  lOO  hp,  440  volt, 
alternating-current  motor. 

A.  K.  (Wise.) 


December,  1921 


THE  ELECTRIC  JOURNAL 


559 


The  coils  are  made  up  of  double  cotton 
covered  conductors  and  to  the  exact 
shape  for  winding  into  the  slots.  They 
are  then  thoroughly  treated  in  a  mois- 
ture resisting  compound.  The  slot  portion 
of  the  coil  is  wrapped  with  a  wrapper 
composed  of  mica  built  up  on  paper. 
The  first  and  last  coil  of  each  group 
where  the  phases  change  are  taped  on  the 
ends  with  treated  tape,  half  overlapped. 
All  coils  arc  then  taped  over  all  with  a 
layer  of  cotton  tape  half  overlapped  on 
the  ends,  but  not  lapped  on  the  slot  por- 
tion of  the  coil.  The  coils  are  then 
thoroughly  treated  in  a  moisture  resist- 
ing compound.  Paraffined  fish  paper  is 
placed  into  the  slots  into  which  the  coils 
are  placed.  The  completely  wound  wind- 
ing is  then  dipped  in  a  moisture  resist- 
ing \^rnish  two  or  more  times,  draining 
and  drying  it  in  a  heater  after  each  dipp- 
ing. J.  I"  R. 

2070 — Transmission  Line  Construction 
— Are  there  any  good  reasons  for  not 
adopting  a  method  of  increasing  the 
capacity  of  an  existing  6600  volt  trans- 
mission line  two  miles  long  by  string- 
ing a  second  300000  circ.  mil.  cable  be- 
low the  present  one,  which  is  sup- 
ported by  a  suspension  disk;  provided 
of  course  that  all  other  factors  enter- 
ing the  problem,  such  as  strength  of 
towers,  wire  spacing,  ultimate  tensile 
strength  of  suspension  and  strain  in- 
sulators, etc.  would  allow  such 
practice.  M.  G.  A.   (Asiz). 

The  addition  of  the  300  000  cir.  mil. 
cable  will  be  satisfactory  and  will  in- 
crease the  capacity  of  the  existing  line 
from  8700  to  14  500  kv-a  approximately, 
based  on  a  temperature  rise  of  from  10 
to  IS  degrees  C.  The  division  of  current 
between  the  two  cables  is  such  that  the 
smaller  cable  will  carry  48  percent  of  the 


FIG.  2070  (a) 


total  current.  The  rated  carrying 
capacity  of  a  500000  circ.  mil.  cable  is 
755  amperes  for  a  10  degree  C.  tempera- 
ture rise  and  for  a  300000  circ.  mil. 
cable,  515  amperes.  Of  the  total  current 
of  1275  amperes  the  smaller  cable  must 
carry  48  percent  or  610  amperes,  which 
is  in  excess  of  the  value  given  above  and 
corresponds  to  a  temperature  rise  of  ap- 
proximately 15  degrees  C.  The  larger 
cable  carrying  665  amperes  would  h.ive 
a  temperature  rise  of  8  degrees  C.  The 
calculation  of  the  division  of  current  in 
the  two  cables  is  as  follows : — 

-  Ma/a) (/) 

E^  =  /?2/j  4-/0,  {Uh  +  ^h^h 

-  MiaIj^j {2) 

where  £,  and  E,  =  Voltage  drop  in  the 
cables. 

Ri  and  R.  =  Resistance  of  cables. 

h  and  U  =^  Current  in  cables. 

Li  and  L.  =  Self-inductance  of 
each  cable. 

Af,s  and  M21  =  Mutual  Induct- 
ance between  two  cables. 

Mit.  and  AfiA  =  Mutual  Induct- 


ance between  each  cable  and  the 
return  circuit. 
El  must  equal  Ei 
Subtracting  (2)  from  (l) 

O  =  A-,/,  -  AWi  +-yco  [Zi/i  -  A2/2 

+  M,j  (/-,-  /,)] (3) 

(A/iA  is    assumed    to    be    equal    to  Mia 

which  is  a  very  close  approximation) 

/,  [A'l  +  /u  f/.i  -7)/i.O]  = 

/■[A'... +/u)  (/.«  -A/,:)\ (v) 

Then, 

h  ~  A-i  +  yo)  (A.-ii/ii,) ^> 

The  self-inductance  of  each  cable  may 
be  calculated  from  Equation  (6)  which  is 
the  same  as  equation  (95),  page  151, 
Bureau  of  Standards  Bulletin  169. 

L    =2l{^0g,'-^^    -    3<) (^) 

Where    L^  Inductance    in    centimeters 

(Multiplying  by  lo~'i  to  reduce 

to  henrys) 

/=  Length     of     conductor      in 

centimeters. 
7?g  =  Geometric  mean  radius  of 

conductor 
Rt  '=■  o.7788r  where  r  ^  radius 
of  conductor 
The  mutual  inductance  between  con- 
ductors is  calculated  from  equation  (7), 
which  is  the  same  as  equation  (qq),  page 
151  Bureau  of  Standards  Bulletin  169. 

/          2/               d  \ 
M=2l\lo,s,,-^-,  +— j (7) 

Where  Af  =  inductance  in  centimeters 
(Multiplying  by  io~''  to  reduce  to 
henrys). 

d  ■=  distance  between  conductors 
in  centimeters. 

From  (6)  and  (7) 

L~isr=2i(iog,^^-  k) 

(         2I  d  \ 

-  2  l\log,^-, +  -)._. {S) 

I         2ld  d\ 

-^log^R^i^y.-T) w 

(  d  \      .        d 

=  'lyog,-jT^  +  %^   smce  — 

is  negligible {10) 

Length  of  line  (2  miles)  =  321  869 
centimeters. 

L 1  -  Mvi  =  6/j  73S  (log,-^  +h) 

=  2  S60  000 
=0.00286  henry ;  hence  X  =  1.078 
ohms,   assuming  that  the  average   spac- 
ing of  conductors  is  10  inches. 

t^,_  j,r,„_  =  6,373s  [log.  ^  +  h) 

=  2  /oo  000 
=  .00270  henry;  hence  X  =  1.02 
ohms. 
Substituting  in  equation  (5), — 
_A  _    o..'34  +Jr.o-> 
!■■  "  0.302  -|-  j  r.O/S 
The  percent  of  total  current  flowing  in 
the  smaller  conductor  is  then : — 
/i   X    100      0.2^4  -\-  j  1 .02 

/i  +  h    "  0.626  +j  2.ogS  ^  '""  = 
2.2S6  -f  10.148  22g 

—s ^  '"^  =  T^  =  ^^-^ 

W.  E.  D. 

2071 — Re.  Question  igSo — Relative  to 
question  No.  1980,  please  explain  how 
the  capacity  of  the  transformer  second- 
ary is  figured  to  be  350  kv-a.  I  realize 
this  350  kv-a  is  220  volts,  three-phase, 


feeding  from  the  middle  points  of  the 
three  200  kv-a  transformers. 

w.  M.  E.  (III.) 
Fig.  (a)  indicates  the  loading  on  the 
secondary  of  the  bank.  The  load  current 
of  any  phase  has  two  parallel  paths 
through  the  transformers.  For  instance, 
phase  AB  has  one  path.  A,  1,  B  and 
another  path  A,_  3,  C,  2,  B.  The  first 
mentioned  path  is  one-half  the  length  of 
the  second  path ;  therefore,  the  current 
will  divide  between  these  two  circuits  in 
the  ratio  i :  2.  Let  /p  represent  the  cur- 
rent that  passes  any  point  between  B  and 
A  in  the  secondary  windings.  Then,  with 
an  equal  load  on  all  phases, 
/p  =  %  /.vB  —  Vs  /bc  —  %  /oA. . . .  (i) 
If  the  secondary  load  is  balanced  and 
/ab  —  1,  then 
/bo  =  {-Y2—]  0.866)  / 
/cA  =  (-¥2  4-  j  0.866)  / 
Substituting  the  values  for  /bo  and  /oa 
in  equation  (i),  it  will  be  found  that  /p 
=  /.  that  is,  the  current  in  the  secondary 
of  the  transformers  is  equal  to  the  220 
volt  phase  current.  The  normal  current 
.  200  000 
in  the  transformer  secondary  is  ttt 
440 

=  445  amperes,  therefore,  the  220  volt 
load  that  gives  normal  current  in  the 
transformer  secondary'  =  445  X  220  X 
3  =  300  kv-a,  balanced  three-phase.  The 
transformer  primary  supplying  300  kv-a 
will,  however,  he  only  one-half  loaded, 
therefore  the  loss,  and  consequcntlv  the 
timperati'.-.'"  will  be  below  normal.  Willi 


FIG.  2071   (a) 

equal  amounts  of  copper  in  the  primary 
and  secondary  the  sum  of  the  losses  will 
be  normal  when  the  transformer  is  de- 
livering 380  kv-a,  which  gives  63  percent 
load  on  the  primary  and  127  percent 
load  on  the  secondary.  But  normal  tem- 
perature would  be  exceeded  at  380  kv-a 
as  the  total  loss  is  normal,  but  the 
secondary  temperature  gradient  would 
be  hig-h  on  account  of  it  being  over- 
loaded. In  order  to  compensate  for  this 
the  load  must  be  reduced.  It  will  be 
found  that  350-kv-a,  which  gives  117 
percent  load  on  secondary  and  58  per- 
cent load  on  primary  or  86  percent  of 
normal  copper  losses,  will  give  approxi- 
mately normal  temperature  rise  in  the 
secondary  of  the  transformer.        J.  F.  P. 

2072— Cross-Connected  Relay  System 
— Fig.  (a)  is  a  diagram  of  a  cross- 
connected  relay  system  described  in  an 
article  by  Mr.  L.  N.  Crichton  in  the 
JouKNAL.  The  arrows  indicate  the 
direction  of  flow  of  current  in  the 
transformers,  relays  etc.,  with  a  short- 
circuit  on  feeder  D  as  shown.  As  the 
arrows  show,  the  reverse  power  relays 
are  tripping  out  their  respective  cir- 
cuit breakers  on  both  ends  of  the 
feeder  in  trouble.  I  can  readily  see 
where  there  is  a  reversal  of  povyer 
flow  causing  relay  8  on  the  sub-station 
end  of  the  defective  feeder,  to  trip,  but 
fail  to  understand  what  is  causing  the 
circuit  breaker  on  the  station  end  of 
the  feeder  to  trip,  as  there  is  appar- 
ently no  reversal  of  power  flow  here. 
Can  you  tell  me  why  the  current  flow 
in  relays  i,  2  and  3  is  the  reverse  of 


56o 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


that  in  4,  5,  6  and  7  when  the  current 
in  their  respective  transformers,  flows 
the  same  way.  H.  r.  l.  (penna.) 

In  this  relay  connection  or  in  any 
other  method  of  using  directional  relays^ 
it  is  not  necessary  to  have  a  reversal  of 
power  flowing  in  order  to  cause  a  relay 
to  trip.  Directional  relays  intended  for 
line  protection  are  so  connected  in  the 
circuit  that  they  will  operate  when  the 
power  is  flowing  away  from  the  bus- 
bars which  may  be  the  normal  direction. 
In  the  cross-connected  scheme  there  is 
no  current  in  the  relays  under  norma! 
conditions.  When  the  current  is  the  same 
in  all  the  lines,  the  secondary  current 
flows  around  the  loop  through  the  trans- 
formers and  does  not  go  through  the  re- 
lays due  to  their  impedance.  When  one 
line  carries  more  current  than  the  others, 
the  excess  secondary  current  will  be 
forced  through  the  relays,  part  of  it 
through  relay  No.  4,  and  the  remainder 
through  relays  i,  2  and  3  in  series.  That 
the  direction  of  the  arrows  on  relays  I,  2 
and  3  is  correct  is  evident  if  you  keep  in 
mind  that  the  terminal  A^  on  relay  4  is 
at  a  higher  potential  than  the  other  ter- 
minal and  that  terminal  N  on  relay  4  is 
at  the  same  potential  as  terminal  M  on 


circuit  can  easily  be  obtained.  The  con- 
ditions at  the  substation  end  of  the  lines 
are  similarly  shown  in  Figs,  (e)  and 
(f).  I-  N.  c. 

2073 — Testing  Transformer — We  have 
a  220  watt  air-cooled  potential  trans- 
former. 60  cycles,  2  200  volts  primary, 
122  volts  secondary  with  a  middle  tap. 
Please  advise  if  we  can  use  it  for  test- 
ing insulation  of  coils,  twin  wires, 
etc.,  at  about  4  000  volts  or  less  with 
the  connection  shown  in  Fig.  (a). 
We  have  put  110  volts  across  the 
middle  tap  and  one  outside  wire  with- 
out any  trouble  for  a  short  length 
of  time  (about  5  minutes).  How 
can  I  calculate  the  testing  voltage 
from  the  incoming  value — that  is, 
within  no  volts  of  the  true  voltage. 
What  voltage  should  I  get  (appro.xi- 
niately)  on  the  high  voltage  side,  with 
no  volts  connected  as  shown? 

R.  A.  B.  (mass.) 
Since  the  transformer  in  question  has 
rated  voltages  of  2  200  high  voltage 
and  122  low  voltage — the  ratio  of 
transformation  must  be  18  to  1.  Using 
one-half  of  the  low  voltage  winding 
will  give  a  ratio  of  36  to  i,  consequently 
no  volts  applied  to  the  middle  tap  and 
one  outside  wire  of  the  low  voltage 
winding  \vill  give  110X36  =  3960  volts 
on  the  high  voltage  side.  It  must  be 
recognized,    however,    that   by    applying 


FIGS.  2072— (a)  to  (f). 

relay  i.  A  convenient  method  of  analyz- 
ing the  circuit  is  shown  in  Figs,  (b), 
(c),  (d),  (e)  and  f.  Assume  that  the 
fault  draws  six  amperes,  from  the  line 
in  which  it  occurs,  and  that  each  of  the 
other  lini'S  Iced  into  it,  two  amperes. 
Since  the  current  is  the  same  in  all  good 
lines,  the  current  transformers  can  be 
represented  as  being  placed  in  series  on 
one  line,  as  shown  in  Fig.  (c).  Now  the 
current  from  the  current  transformer  Si 
through  the  jumper  X  into  the  relay  i?j 
is  just  balanced  by  the  current  in  the 
opposite  direction  in  transformer  5":.  In 
other  words,  there  is  no  current  flowing 
in  the  jumpers  X  and  Y  and  consequent- 
ly they  may  be  omitted  (for  purpose  of 
analysis)  as  shown  in  Fig.  (d).  It  is 
evident  that  the  current  which  will  flow 
through  the  relays  is  the  difference 
between  the  current  from  the  transform- 
ers in  the  good  lines  and  the  transformer 
in  the  bad  line.  The  current  which  flows 
between  M'  and  A''  through  the  relays 
divides  inversely  as  the  impedance  of  the 
two  circuits.  If  it  is  also  borne  in  mind 
that  the  potential  is  the  same  between 
points  M'  and  N',  no  matter  through 
which  of  the  four  paths  the  current  may 
be  traced,  the  solution  of  any  part  of  the 


A  polyphase  meter,  properly  cali- 
brated and  correctly  connected  will  be- 
have as  you  have  described,  at  certain 
conditions  of  changing  power-factor. 
Briefly,  stated  the  torque  on  one  ele- 
ment of  a  polyphase  meter  is  zero  at 
50  percent  power-factor.  At  power 
factors  below  50  percent  the  torque  is 
negative  on  the  same  element,  while  at 
power- factors  above  50  percent  the 
torque  is  positive.  Therefore,  as  the 
power-factor  changed  from  values  be- 
low 50  percent  to  values  above  50  per- 
cent the  direction  of  rotation  of  the  disk 
would  change  from  negative  to  positive, 
if  the  other  element  is  disconnected. 
For  detail  data  see  Metermans  Hand- 
book, pp.  167  to  175;  Meter  Code,  pp. 
86  to  93 ;  "A  Method  of  Determining 
the  Correctness  of  Polyphase  Watt- 
meter Connections",  by  W.  B.  Kouwen- 
hoven,  .\.  I.  E.  R  Feb.  1916;  and  "A 
Study  of  Three-Phase  Wattmeter  Con- 
nections" by  C.  R.  Riker,  in  the  Journal 
for  Sept  1912,  p.  765.  ■       A.  R.  K. 

2075 — Connection  for  Lightning  .Ar- 
resters— We  have  installed  some 
lightning  arresters  as  shown  in  Fig. 
(a).  Would  you  call  that  a  delta  or 
star  connection?  a.  a.  ( Mexico") 

We  would  call  the  connection  in 
Fig.  (a),  a  star  connection.  To  be  ef- 
fective the  arresters  in  Fig.  (a)  should 
have  a  ground  connection.  If  the  sys- 
tem has  the  neutral  grounded  the 
ground    connection    should   be   attached 


O.OOOQ 


M0W0"0"OW071 


FIG.  2073 — (a) 

no  volts  to  one-half  of  the  low  voltage 
winding,  the  insulation  of  the  trans- 
former will  be  subjected  to  a  voltage 
strain,  eighty  percent  above  normal. 
Furthermore  180  percent  of  normal 
voltage  applied  to  one-half  of  the  low 
voltage  winding,  may  cause  an  excessive 
value  of  exciting  current,  suflficient  to 
overheat  the  winding.  The  plan  is  not 
to  be  recommended.  However,  it  might 
be  used  in  an  emergency  for  very  short 
time  service.  e.  I-  c. 

2074 — Unsatisfactory  Operation  of 
Watthour  Meter — We  are  having 
trouble  with  a  2  200  volt,  200  ampere, 
60  cycle,  Watthour  Meter,  operating 
on  a  three-phase,  2  200  volt  circuit 
connected  in  the  conventional  way 
through  potential  and  current  trans- 
formers. The  meter  is  used  to  re- 
cord the  entire  station  output.  On 
one  phase  the  meter  will  rotate  very 
slowly-and  seem  to  hesitate  at  some 
point  in  the  revolution.  In  some  tests 
it  reverses  or  seems  to  do  so  while 
on  the  other  phase  it  operates  cor- 
rectly. In  an  attempt  to  correct  the 
trouble  the  meter  was  first  sent  to 
the  factory,  tested  and  calibrated  and 
O.  K'ed  by  them.  A  set  of  two  po- 
tential and  two  current  transformers 
of  the  portable  type  were  installed 
in  place  of  the  switchboard  type  but 
this  did  not  correct  the  trouble.  Two 
meters  of  the  same  type  are  operating 
satisfactorily  on  out  going  circuits 
on   the   same   switchboard. 

C.    H.   B.    (new  jersey) 


Wire  Grounded 
Ntulral  Syslem 


Arresler         1 
GrouiKl       "^ 

(0 

FIGS.  207S— (a),   (b)   and   (c) 

to  the  common  connection  of  the  ar- 
resters shown  in  Fig.  (b).  If  the 
neutral  of  the  system  is  not  grounded 
a  fourth  arrester  should  be  placed  be- 
tween the  fourth  lead  and  the  ground 
connection.  The  fourth  arrester  in  Fig. 
(c)  may  be  good  for  either  too  percent 
or  58  percent  of  the  line  voltage. 

G.  C.  D, 


December,  1921 


THE  ELECTRIC  JOURNAL 


19 


An  18-Year  Old  Vitrohm  Set 


Here  in  the  power 
plant  of  the  Metro- 
politan Building, 
New  York,  is  a  strik- 
ing example  of  the 
real  sturdiness  of 


Vitrohm  Field  Rheostats  ^S 


Note  how  these  units  are  ahnost  duplicates  of 
our  present-day  product.  I^ook  back  at  j'our 
motor  or  transformer  built  18  years  ago — 
compare  their  1903crudeness  with  the  present- 
day  refinements — then  consider  the  originality, 
the  correct  engineering  knowledge  that  enabled 
H.  Ward  Leonard  (the  founder  of  our  com- 
pany) to  design  and  build  Vitrohm  units  25 
years  ago. 

This  Metropolitan  job  of  tour  generators 
equipped  with  Vitrohm  Rheostats  has  been 
operating  satisfactorily  daily  for  each  and 
every  day  of  the  eighteen  years.  It  is  this 
kind  of  service  that  has  caused  the  growth  of 
Ward  Leonard  to  its  present  size. 

The  construction  of  Ward  Leonard   N'itrohm 


Field  Rheostats  is  fundamentally  the  same  to- 
day as  in  1003.  Solid  grids,  with  Vitrohm, 
vitreous  enamelled  insulation  enveloping  and 
protecting  the  resistance  element  against  cor- 
rosion or  oxidation,  which  would  destroy  ordi- 
nary resistance  wire  when  heated  and  cooled 
in  service. 

If  you  have  resistance  problems  in  connection 
with  plant  operation  or  manufacture  of  electri- 
cal apparatus,  our  experts  will  gladly  assist 
in  their  solution. 

W'e  will  gladly  send  you  a  free  sample  Mt- 
rohm  Resistor  Unit  (vitreous  enamelled,  just 
like  Vitrohm  Rheostats)  so  j^ou  can  see  and 
test  for  yourself  the  properties  of  Vitrohm. 


Ward  Leonard/Tectric  Company 


W.lter  W.  Caskill-Boston 

WUIiBm  Miller  Tompkins— Philadelphia 

Walter  P.  Ambos  Co.— Cleveland 

Wm.  C.  Merowit,  Buffalo 

Sperry&  Bittner,  Pittsburgh 

Intermountain  Sales  Co.,  Denver 


'yWount    ^ 
Vernon. 
Xewybrk. 


Westburg  Engineering  Co.— Chlci 
Electric  Material  Co.— San  Francii 
Electric  Material  Co.— Los  Angelei 
Electrical  Specialties  Co.— Detroit 
Ceo.  W.  Piel4sen-St.  Louis 
Wm.  Geipel  &  Co.,  London,  Engia 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


20 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII.  No.  12 


THE  HARRINGTON  ROCKING  CA- 

BLEWAY    FOR    MATERIAL 

HANDLING 


One  of  the  problems  of  central  sta- 
tions, as  well  as  steel  mills  and  other 
manufacturing  concerns  is  the  economi- 
cal handling  of  material  such  as  coal, 
ashes,  etc.  In  cases  where  a  permanent 
storage  space  is  desired  the  expense  of 
steel  structures  for  the  material  hand- 
ling devices  may  be  justified.  However, 
the  Railway  &  Industrial  Engineering 
Company  of  Greensburg,  Penna.,  have 
recently  developed  a  conveying  system 
that  seems  to  have  all  the  merits  of 
previous  systems  without  involving 
heavy  expense  in  structural  materials. 
The  Harrington  Rocking  Cableway,  as 
illustrated,  makes  use  of  swinging  end 
supports  for  the  cable  and  these  sup- 
ports  are   counterweighted   so   that   the 


type  and  each  tower  is  counterweighted 
in  such  a  way  that,  after  the  towers 
reach  an  inclination  of  about  45  de- 
grees further  inclination  is  prevented. 
Suitable  arrangements  of  cables  and 
carriers  have  been  developed  so  that 
the  loads  of  material  may  be  dumped 
at  any  desired  location.  Arrangements 
are  made  so  that  the  towers  rock  in 
unison  and  power  for  hoisting  is  sup- 
plied by  electric  motor  or  other 
drive.  The  cableway  can  load  to  and 
from  cars  on  tracks  running  either 
parallel  to  the  side  of  the  pile  or  at  an 
angle  across  the  pile.  Only  one  oper- 
ator is  necessary,  so  that  the  handling 
expense  is  very  low  and  the  operator 
can  be  located  either  at  the  hoist  or  at 
any  other  convenient  point  where  he 
can  view  the  operations.  It  is  claimed 
that  the  cableway  speed  allows  the  mak- 
ing of  two  or  three  trips  of  the  bucket 


A  NEW  AUTOMATIC  STARTER 
FOR  D.  C.  MOTORS 


ioN   OF  THE    HARRINGTON    ROCKING 
CABLEWAY 


FIG.    I — TYPE      SS 

STARTER   WITH   COVER 

CLOSED 


-VltW    Ul     luV.ER    SHOWING    COU-NIEKWEICIIT    IN 
ROCKED   POSITION 


FIG.    2 — TYPE 
STARTER    WITH    COVER 
OPEN 


entire  system  is  balanced.  With  a  sup- 
porting tower  at  each  end  of  the  stor- 
age area  the  overhead  cable  may  be 
moved  to  any  desired  alinement,  so  that 
the  material  can  be  discharged  at  any 
determined  position  in  the  storage  area. 
The  foundations  required  are  simple 
and  are  only  at  the  end  of  the  storage 
area.  The  cableway  can  be  built  to 
serve  an  area  approximately  one  and 
one-half  times  wider  than  the  height 
of  the  towers  themselves.  This  ar- 
rang'ement  is  entirely  independent  of  the 
contour  of  the  ground  in  the  area  to 
be  served  and  the  towers  may  be  at  dif- 
ferent elevations.  There  is  a  tower  at 
each  end  of  the  space  of  the  A-frame 


to  one  trip  of  other  types  of  machines 
such  as  bridge  cranes,  etc.  In  one  in- 
stallation with  a  span  of  220  feet,  the 
average  time  for  a  complete  cycle, 
which  consists  of  loading,  hoisting  and 
moving  the  bucket  diagonally  across  the 
entire  area,  unloading  and  returning  to 
the  loading  point,  was  50  seconds.  The 
speed  of  the  carriage  along  the  main 
cable  is  given  as  800  feet  per  minute 
and  the  hoisting  speed  of  the  bucket 
120  feet  per  minute.  This  development 
should  warrant  the  very  thorough  con- 
sideration of  those  having  to  analyze 
such  problems,  as  the  designers  have 
gotten  entirely  away  from  previous 
methods  used  in  material  handling. 


A  great  many  installations  of  auto- 
matic starters  for  D.  C.  motors  of  10 
H.  P.  or  less  are  in  relatively  remote  or 
inaccessible  places  where  operating  con- 
ditions are  by  no  means  the  best. 
Places  where  such  starters  are  in- 
stalled may  be  damp  or  subject  to  fumes 
which  promote  corrosion,  and  through 
lack  of  attention  it  frequently  happens 
that  the  equipment  which  the  motor 
drives  becomes  clogged,  jammed  or 
blocked  in  some  manner  which  will  pre- 
vent the  motor  from  starting  when  the 
automatic  starter  functions.  The  re- 
sult of  adverse  atmospheric  conditions 
is  the  deterioration  of  the  equipment, 
especially  of  the  starting  resistance. 
The  result  of  the  load  being  blocked 
is  the  burning  of  the  starting  resistance, 
the  motor  or  both,  and  so  there  has  been 
an  extensive  demand  created  for  a 
starter  which  would  withstand  these  ad- 
verse conditions  of  installation  and 
operation.  To  meet  this  demand  The 
Automatic  Reclosing  Circuit  Breaker 
Company  of  Columbus,  Ohio,  has  de- 
veloped, and  placed  on  the  market  its 
Type  "SS"  Automatic  D.  C.  Motor 
Starter.  This  starter  is  designed  for 
_'50  or  500  volt  service  in  capacities  of 
?>■  5.  7V2,  and  10  hp.  It  is  of  the  counter- 
c  m.  f.  type  with  one  step  of  resistance 
which  is  automatically  cut  out  when  the 
motor  comes  up  to  speed.  This  resist- 
ance is  made  of  nickel  and  chromium 
alloy  wire,  the  very  highest  gfradc  ma- 
terial available  for  withstanding  corro- 
sion, and  is  of  such  value  that  it  limits 
the  starting  current  to  the  full-load 
current  of  the  motor  and  of  sufficient 
capacity  to  carry  this  current  indefi- 
nitely. These  elements  of  design  give 
the  type  "SS"  starter  the  special  and 
important  charcteristics  of  protecting 
the  motor,  should  it  fail  to  start  its  load, 
against  burning  out  of  cither  motor  or 
starter,  and  insuring  the  very  longest 
life  under  adverse  atmospheric  condi- 
tions. 

This  starter  is  applicable  where  the 
starting  torque  required  does  not  exceed 
the  full  torque  of  the  motor  and,  in  a 
very  large  percentage  of  installations 
of  motors  of  this  capacity,  it  is  found 
that  the  starting  torque  required,  no- 
where nearly  equals  the  full-load  torque 
of  the  motor.  Especially  is  this  true  of 
motors  driving  pumps,  blowers  and  ro- 
tating apparatus  not  having  excessive 
static  or  starting  friction,  or  where  the 
load  comes  on  as  or  after  the  motor 
comes  up  to  speed.  As  shown  in  Fig. 
I,  the  type  "SS"  starter  comorises  two 
units;  one  the  starting  resistance 
mounted  and  completely  housed  in  a 
perforated  sheet  iron  box.  Connections 
between  the  starting  panel  and  resist- 
.  ance  are  made  at  the  time  of  installa- 
tion. The  cover  and  the  box  housing 
the  panel  are  provided  with  lugs  for  re- 
ceiving a  padlock  so  that  the  panel  may 
be  secured  against  exposure  of  any  live 
parts  or  molestation  by  unauthorized 
persons.  Fig.  i  shows  the  box  with  the 
cover  closed  and  Fig.  2  with  the  cover 
open.  The  construction  of  all  details  of 
this  starter  is  rigid  and  substantial  and 
all  current  carrying  parts  of  ample  ca- 
pacity. The  guiding  thought  has  been 
to  produce  a  reliable  and  durable 
starter  without  sacrifices  in  either  the 
amount  or  quality  of  material  or  work- 
manship. 


December,  1921 


THE   ELECTRIC  JOURXAL 


NEW  BOOKS 


"Space  and  Time  in  Contemporary 
Physics" — Morris  Schlick — 87  pages — 
6  by  9  inches.  PubUshed  by  the  Oxford 
University  Press.  For  sale  by  The 
Electric  Journal.     Price  $2.50. 

Sir  Isaac  Newton's  discussion  of  the 
gravitational  relations  between  heavenly 
bodies  are  highly  mathematical  and  are 
familiar  only  to  astronomers  and  ad- 
vanced physicists.  Nevertheless  every 
high  school  student  has  come  to  under- 
stand the  fundamental  principles  upon 
wliich  Newton's  work  was  based.  It  now 
appears  that  Newton's  work,  while  ac- 
curate, was  incomplete  and  a  broader 
general  theory  of  physics,  which  in- 
cludes all  of  Newton's  theories  as  a 
particular  limited  case  of  the  general 
theory,  has  been  announced  by  Albert 
Einstein.  This  new  theory  has  aroused 
profound  interest  in  scientific  circles  and 
has  been  brilliantly  confirmed  by  astro- 
nomical observations.  It  is  highly 
mathematical  and,  in  its  entirety,  must 
ever  remain  the  sole  property  of 
astronomers  and  advanced  physicists. 
As  with  Newton's  theories,  however,  the 
general  principles  upon  which  it  is  based 
can  be  understood  by  the  layman,  once 
he  adapts  his  mental  concepts  to  an  en- 
tirely new  viewpoint.  Schlick's  book  on 
"Space  and  Time"  gives,  as  comprehen- 
sively as  is  possible  with  only  simple 
mathematics,  -an  explanation  of  the 
general  and  special  theories  of  relativity, 
and  a  general  discussion  of  the  applica- 
tion of  Einstein's  work  to  modem 
physics,  concluding  with  a  discussion  of 
the  finitude  of  the  universe  and  the  rela- 
tions of  the  new  physics  to  philosophy, 
which  is  somewhat  startling  to  one  who 
has  not  yet  adapted  his  mind  to  the  new 
ideas.  c.  r.  r. 


As  in  other  text  by  this  author  much 
attention  has  been  given  to  the  matter 
of  illustrations  to  aid  readers  in  getting 
a  clearer  understanding  of  principles. 
For  a  book  of  this  kind  it  would  seem 
that  the  author  has  rather  gone  to  ex- 
tremes in  introducing  discussions  on 
such  terms  as  elastance,  darafs  ("fa- 
rads spelled  backwards")  etc.  Even 
discussions  on  resonance  and  similar 
expressions  would  seem  to  confuse 
rather  than  aid  the  practical  electrician 
who  really  has  little  use  for  such  terms 
in  his  ever>-day  work.  Of  course,  it  is 
easy  enough  for  one  to  skip  such  sec- 
tions in  a  book  but,  for  a  work  of  the 
extremely  practical  type,  it  would  seem 
better  for  the  author  to  play  safe  by  not 
attempting  to  show  off  his  entire  box 
of  tricks.  The  book  as  a  whole,  of 
course,  is  excellent  and  the  above  com- 
ments cover  only  minor  details. 


"Service  at  Cost  Plans"— Harlow  C. 
Clark— 31S  pages.  Published  by  Ameri- 
can Electric  Railway  Association,  New 
York  City.     Price  $2.50. 

Of  all  the  local  utilities,  the  street  rail- 
ways have  manifestly  suffered  most  at 
the  hands  of  city  governments.  For 
years  street  railways  were  the  football 
of  local  politicians.  The  rising  tide  of 
prices  only  served  to  crystalize  the  em- 
barrassing situation  some  had  already 
reached  and  towards  which  others  were 
rapidly  drifting.  As  Mr.  Clark  explains, 
the  street  railway  is  next  in  order  to 
sewage  and  water  works  systems  in  the 
matter  of  importance  to  urban  life. 
Therefore,  it  is  essential  that  the  ob- 
stacles to  the  solution  of  the  local  trans- 
portation problem  be  removed.  Munici- 
pal ownership  is  invariably  wasteful 
and,  therefore,  creates  extra  burdens  for 
the  tax  payers.  Cost-plus  plans  are 
next  in  line  in  eliminating  the  undesir- 
able antagonism  and  this  book  is  devot- 
ed to  a  thorough  discussion  of  the  his- 
tory of  such  methods  of  regulation.  In 
many  of  the  more  recent  cases,  broader 
provisions  have  been  inserted  in  the 
agreements.  This  work  is  so  arranged 
as  to  present  clearly  these  facts  and 
should,  therefore,  serve  a  most  useful 
purpose  in  aiding  the  utilities  to  secure 
not  only  fair  treatment  but  suiScent  con- 
sideration to  stir  private  initiative  to  ac- 
complish greater  public  service  and  con- 
venience. E.  D.  D. 


"Practical  Electricity"  —Terrell  Croft, 
646  pages,  548  illustrations,  Published 
by  McGraw-Hill  Book  Company, 
Price  $3.00. 

This  is  the  second  edition  of  this 
work  originally  published  in  1917.  It 
covers  substantially  the  same  ground  as 
the  first  edition,  that  is,  it  aims  to  give 
the  fundamental  facts  and  theories  re- 
lating to  electricity  and  its  application, 
in  a  simple  style  so  that  even  the 
readers  who  only  understand  arithmetic 
will    be    able    to    read    understandingly. 


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THE   ELECTRIC  JOURNAL 


23 


/ J 


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Moo 


When  a  Hindu  gets  seriously  ill,  his  folks  carry  him  to  the 
Ganges  river.  There,  with  his  body  almost  wholly  im- 
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advice  from  a  Morganite  prescriber. 
It's  the  only  way  to  get  deliverance  because — 
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LLIE  Corp. 

Boston.  Mass. 


W.  R.  Hendrey  Co. 
Hoge  Building  -  -  Seattle,  Wash- 

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150  Steuart  Street  -  San  Francisco,  Cal. 

Special  Service  Sales  Co. 
502  Delta  Building  .  -  Los  Angeles.  Cal. 

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THE  ELECTRIC  JOURNAL 


Vol.  XMII,  No.  i: 


Organized  1899 


Reorganized  1917 


REPAIR  WORK 


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December,  192 1 


THE  ELECTRIC  JOURNAL 


25 


A  Photostat  Would  Have  Prevented 
Such  a  Mistake 

Laving  Ihehlame  on  the  drafting  room  doesn't  help  us  Theoretic- 
all  V  they  should  have  noticed  those  transposed  hgures  when  they  checke.l 
^he  tracings!  but  the  fact  remains  that  the  error  crept  m  .n  sptte  of  the 
checkmg^  is  the  result  ?  It  will  cost  us  our  entire  profit  on  the  job  to 
correct  the  results  of  that  mistake.  And  we  could  have  bought  several 
PHOTOSTATS  with  what  we  will  lose.  t>l,r^•rr.cTi  x 

That  mistake  couldn't  have  occurred  if  we  had  made  PHOTOSTAT 
copies  of  the  blueprint  instead  of-  tracing  it.  The  PHOTOSTAT  makes 
photographic  facsmiiles  so  vou  don't  even  have  to  check  them. 

And  compare  the  time  it  takes  to  make  PHOTOSTAT  copies  against 
the  time  it  took  our  drafting  room  to  trace  that  blueprint  and  to  make 
additional  blueprints.  Why,  it's  a  matter  of  minutes  against  hours.  By 
copying  blueprints,  pencil  sketches,  drawings  and  orders  with  the 
PHOTOSTAT  we  can  get  all  our  work  into  the  shop  days  earlier  than  we 


do 


I  teil  you,  no  matter  from  ' 
r  of  the  PHOTOSTAT. 


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1  look  at  it.  everything 


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299  State  Street,  Rochester,  N.  Y. 


88  Broad  Street,  Boston 
7  Dey  Street.  New  York  City 
429  Monadnock  Bldg  .  San  Francisco 
Executive  Office: 


19  South  LaSalle  Street,  Chicago 
SIO  North  American  Bldg  .  Philadelphia 
601  McUchlen  Bldg.,  Washington 
PROVIDENCE,  R   I. 


Electricians'  Knife 
Scissors  and  Tweezers 

We  can  meet    dealers    demands  at  once 
and  offer  attractive  quantity  prices 

Write  for  description 

MATHIAS  KLEIN  &  SONS,  Mfrs. 

CANAL  STA.  3,  CHICAGO 


BRUSH  DATA  SHEET 

National  Carbon  Company,  Inc. 


dat^ 


DATA  ,„,  converter. 

otor   generator  or      ^^,^shes, 


„.t  tto  wrong  D> 


,  Carbon  Brushes 

^"*''°rdbV  expert  engineers. 
,3  recommended  bV  y,  \nC. 


A 


(halfonte- 

tlADDONHALL 

ATLANTIC  CITY,  N.  J. 

These  two  most  favored  of  Atlantic  City's 
famous  hotels  now  combined.  Same  home- 
like comforts  and  hospitality — with  added 
facilities  and  greater  charm. 
Beautiful  pavilions  and  sun  parlors.  Broad 
deck-porches  overlooking  the  sea.  Pleasant 
rooms.  Good  food,  perfectly  cooked,  per- 
fectly served.   Golf  club  privileges. 

On  ,heB<ra,har,dlh,Boj'ii-u'Mi.   American  PUn 
ih,h     n  nte  for  ,lhutrahj  folder  and  raUi. 

LEEDS  and  LIPPINCOTT  COMPANY 


Please  mention  The  Electric  Journal  zvhen  writing  to  advertisers 


26 


THE  ELECTRIC  JOVRXAL 


Vol.  XMII,  No.  12 


4NAC0NDA 

BARE  COPPER 
WIRE 

STRAMDED  CON- 
DUCTORS OFANY 
DESIRED  CAPACITY 

TROLLEY  WIRE 

flnacondA  Coppei^   k. 
'  Mining  Compa^ny  ;\ 

(         ROLLinO-  MILLS  DEPY. 

j  541  Conway  Bldj,  Chicago 


hl'r^m  QiV  ^'^  ^inrshpd  Prodi 


Galena  Quality 

zizzzZm  and  :r:r:;;z:r: 

Galena  Service 

are  the  Factors  that  Produce  Perfect 

Lubricating  Efficiency 


The  acknowledged  leadership  of  Galena  Car,  Engine, 
Valve,  Signal,  Railway  Safety  and  Long  Time  Burner  Oils 
is  the  result  of  fifty  year's  devotion  to  a  quality  ideal. 
Galena  supremacy  is  due  to  unapproachable  quality  and 
service,  combined  with  scientific  knowledge  of  lubrication 
in  all  its  phases. 

The  Galena-Signal  Oil  Co. 
Franklin,  Pa.  New  York,  N.  Y. 

OFFICES — All  the  Principal  American  Cities 
London  Ptu'is  Buenos  Aires 


Peerless 
Transformers 

In    the    Heart    of    the 
Steel  and  Iron  Industry 

Call    Warren,    Ohio,     1456 

When  You  Need 
Quick  Service 


w^mm 


Fully  Guaranteed 
for     One     Year 

ENTERPRISE 
ELECTRIC    CO., 

Warren,   Ohio 

LIST  OF  AGENCIES: 
THE  WALTERP.  AMBOS  CO., 

983  The  Arcade.  Cleveland,  O. 
THE  MOOCK  ELECTRIC  SUPPLY  CO., 
Cor.  Cleveland  Ave.  &  Fifth  St.,  N.  W., 
Canton,  O 
THE  NATIONAL  ELECTRICAL  SUP.  CO., 
1330  New  York  Ave.,  Washington,  D.  C. 
THE  LEE  ELECTRIC  CO., 

217  North  Calvert  St.,  Baltimore,  Md. 
THE  McCULLOUGH  ELECTRIC  CO., 

First  Ave.,  Pittsburgh,  Pa. 

THE  GEE  ELECTRIC  CO., 

Wheeling,  W.  Va. 

THE  MOORE-HANDLEY  H'DWARE  CO., 

Birmingham,  Ala. 


Please  mention  The  Electric  Journal  when  Kriting  to  advertisers 


December,  1921 


THE  ELECTRIC  JOURNAL 


27 


MOLONEY   TRANSFORMERS 


The  special  virtues  and  tlie  special  values 
attributed  to  MOLONEY  TRANSFORMERS 
are  the  simple  results  of  sound  manufacturing 
policies. 

Our  production  processes  have  been  developed, 
and  carried  closer  and  closer  to  perfection,  in 
our  factories.  MOLONEY  workmen,  in  MO- 
LONEY plants,  build  practically  every  im- 
portant unit  of  the  transformer. 

The  point  is  that  MOLONEY  COMPANY'S 
methods  are  highly  regarded  by  other  manu- 
facturers; and  that  the  greater  value  which  you 
recognize  in  MOLONEY  TRANSFORMERS 

is  directly  due  to  those  methods. 


MOLONEY  ELECTRIC  CO. 

Manufacturers  oj  Better  Transformers 


St.  Louis,  Mo. 
Windsor,  Can. 


OFFICES: 

New  York  Los  Angeles  Atlanta 

Philadelphia       Salt  Lake  City  Pittsburgh 

Chicago  Minneapolis  Detroit 

Cleveland  Seattle  Charlotte,  N'.  C. 

Indianapolis        San  Francisco  Kansas  City 


PELTON 


EXACT  REGULATION  AND  APPLICATION 


The  Hoyeinger  Plant  of  the  Norsk-Aluminum  Company 
of  Norway  consists  of  seven  Pelton  impulse  turbines  op- 
erating under  1800  and  2400  feet  heads,  direct  connected 
to  300  volt,  10.000  amp.  D.  C.  generators  which  supply 
power  for  electrolytic  reduction.  The  requirements  of 
this  plant  necessitate  reducing  the  voltage  from  300  to 
60  volts  during  periods  when  electrodes  are  being  changed 
and  the  turbine  regulation  is  so  exact  that,  even  at  this 
extremely  unstable  point,  the  voltage  is  held  steady  dur- 
ing the  entire  period. 

The  Pelton  Water  Wheel  Co. 

2183  Harrison  Street  83  West  Street 


■■^■■■■■■■■iiiM 


m^ 


■■^^■^HI^iBl^^MBilll 


Please  mention  The  Eleetric  Journal  zvhen  ivritiiig  to  advertisers 


28 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


THE  CIRCUIT  BREAKER  WITH  BRAINS 


Has    substantially    modified    the    circuit 
breaker  art  of  the  world. 


Gives    the    maximum    of    protection    to 
apparatus. 

Reduces  to  a  minimum  delays  due  to  loss 
of  power. 

Increases  your  output. 

Reduces  operating  costs. 

Promotes  safety. 

Is  the  only  circuit  breaker  that  completely 

protects. 


THE  AOTOrWlC  RECLraHC 
QRCOIT  BREAKER  UOHPAWY 


COLUMBUS, 


OHIO 


District  Sales  Offices: 
PITTSBURGH— 223  OLIVER  BUILDING  BIRMINGHAM— 510-512  BROWN-MARX  BUILDING 

PHILADELPHIA— 1613  CHESTNUT  STREET  ST.  LOUIS— 401   NATIONAL  BANK  OF  COMMERCE 

CHARLESTON,  W.  VA.— 110  HALE  STREET  BUILDING 


U.  S.  PORTABLE  ELECTRIC  TOOLS 

Xt 


UQ  DRILLS,  wher 
•v->.  comes  to  the  test 
of  service,  are  provcD  supe- 
riors. If  time  is  a  factor 
again  the  U.  S.  Drills  lead 
in  tests. 


THE  busiest  machine  in 
the  shop.  Put  it  between 
lathes,  or  at  a  convenient 
place,  so  operators  do  not 
lose  time  walking  to  sta- 
tionary grinding  machine. 


the  New  York  Nav>'  Yards,  made 
an  interesting  record.  We'll  send  a 
complete  report  upon  request. 


THIS  grinder  is  made  in 
four  sizes— from  '-j  H.  P. 
to  3  H.  P.  It  is  especially 
adapted  for  grinding  in  the 
lathe,  planer  or  boring  mill 
Air  cooled. 


Doubtless  your  experience  has  led  you  to  believe  that 
elecb-ically  driven  tools  are  in  the  repair  shop  about  half 
the  time.     That  is  because  you  have  never  tried  the  U.  S.  line. 

Write  for  Catalog;  or  better  still ,  let  us  setffl  a  Machine  on  trial, 

THE  UNITED  STATES  ELECTRIC  TOOL  COMPANY 

CINCINNATI,  OHIO 


NEW  YORK  OFFICE 
50  Church  St. 

DETROIT  OFFICE 
Marquette  Building 


BOSTON  OFFICE 
12  Pearl  Street 

CLEVELAND  OFFICE 
5U  Bangor  Building 


ST.  LOUIS  OFFICE 
1506  No.  Broadway 

PHILADELPHIA  OFFICE 
The  Bourse  Building 


CHICAGO  OFFICE 
547  W.  Washington  Blvd 

PITTSBUROH  OFFICB 
Oliver  Building 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


December,  1921 


THE  ELECTRIC  JOURNAL 


29 


^^^vesoF^e/^. 


.^C^f^. 


IStXalSLAt! 
[elect  r  I  c  a  l  [ 

Pyramid  Brand 

SLATE 

used  for  this  Battery  Charging 
Switchboard  with  Motor  Generator 

at   the  Panama     Canal 


This  tested,  finely  hone  -  finished 
and  economical  product  of  nature — 
from  the  famed  Pennsylvania  Slate 
district — is  sent  to  ail  parts  of  the 
world. 

THE   STRUCTURAL   SLATE   CO. 

PEN  ARGVL.  PENNSYLVANIA 


ELECTRICAL    SLATE  &  MARBLE 

OUR  "FAIR  LIST"  No.  7 
Gives  Prices  and  Shipping  Weights  Per  Slab 


fl 

Ul 


(I 


I 


Largest  American  and  Exclusive  Canadian 
Electrical  Slate  and  Marble  Producers 


610-618  East  40th  Street 
CHICAGO,       ILLINOIS 


131  Shaftesbury  Avenue 
TORONTO,     ONTARIO 


■FIVE  FACTORIES- 


ELECTRICAL    SLATE  &  MARBLE 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


THE  ELECTRIC  JOURXAL 


Vol.  XVIII,  No.  12 


HIGH  GRADE  HARD   PORCELAIN 

FOR 

Electrical  Specialties 


.  HIGH  VOLT.AGE  LOW  VOLTAGE 

IMPERIAL  PORCELAIN  WORKS      -      Trenton,  N.J. 

SPECIALTY    PORCELAIN    WORKS 

Devoted   to  the  Design  and  Manufacture  of 

Electrical  Porcelain  for  Special  Purposes 

Correspondence  solicited    with   those   needing 
porcelain  of  unusual  design  or  characteristics 

Individual  expert  attention  given  all  orders 

SPECIALTY   PORCELAIN  WORKS 

EAST  LIX'ERPOOL,  OHIO 


Box  374 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


December,  192 1 


THE  ELECTRIC  JOURNAL 


31 


We   Manufacture  Every 
Known  Carbon   Product 


Automobile  Brushes 


Carbon  Brushes 

For  Slationaiv  Motors  and  Generators, 
Rotary  Converters.  Turbo  Generators 
and  Railway  Motors. 

Carbon  Electrodes 

For  Electric   Furnaces. 

Carbon  Rings 

For  Steam  Turbines. 

Carbon  Rods 

For  Electric  Welding. 

Carbon  Plates  and  Rods 

For  Electrohtic  Work. 

Battery  Carbons 

For  Dry  Cells  and  Flashlight  Batteries. 

Plate  Carbons 

For  Furnace  Lining. 

Projector  Carbons 

For   Motion  Picture  Machines. 

Searchlight  Carbons 

For  Flood  I.ightins  and  Intense  Illuminat 

Studio  Carbons 

For  Moving  Picture  Studio  LightiTig. 

Carbon  Tubes 

For  Protective  Casings. 

Carbon  Contacts 

For  Circuit  Breakers. 

Carbon  Discs 

Fur    relephone  Equipment. 

Carbon  Specialties 

For  all  other  work. 


Twenty   Years'  Experience 


SPEER — The  name  of  quality 


Speer  Carbon  Co. 

St.   Marys,    Pa. 


UPERIOR  COMPOSITION   and   UNIFORMITY 
of  product. 

ROUBLE  eliminated  by  users  of  electrical  apparatus 
with  a  superior  carbon  product. 


ATTAINMENT)  xu      ..  •  .    t 

1  I   1  he  attainment  of 

PPLICATIONJ       shunt  applicatior 


the  ultimate 


K 


0 


OMMUTATION — The  clean,  glossy  appearance  of 
'      commutator  and  the  absence  of  commutator  wear. 

NOWLEDGE — A  product  that  is  the  result  of  ex- 
tensive experiments  and  a  thorough  practical  and 
technical  knowledge  of  carbon  requirements. 

I  ROMPT  SHIPMENTS— In  case  of  extreme  neces- 
sity immediate  partial  shipments  on  receipt  of  order 

PERATION — Each  grade  selected  for  the  service 
specified  or  required  only  after  exhaustive  tests  both 
in  the  laboratories  and  under  actual  operating 
conditions. 

UBRICATING  QUALITIES— Carbon  brushes  that 
are  self-Iubricating  due  to  the  exceptionally  high 
grade  material  used  in  their  manufacture. 

XCELLENT  WEARING  QUALITIES— Proven  by 
long  life,  absence  of  commutator  wear  and  thous- 
ands of  satisfied  customers. 


'STACKPOLE" — the  word    that   stands    for 'efficiency 
to  the  users  of  all  known  carbon  products 


STACKPOLE  CARBON  COMPANY 

St.  Marys,    Pennsylvania 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


32 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


OF 

WILKES-BARRE 


ISTS 


Safety  the  First  Consideration 

Any  hoist,  used  where  men  are  to  be  raised  and  lowered,  must  give 
first  consideration  to  safety.  Though  it  is  not  quite  so  vital  where 
material  only  is  to  be  hoisted,  safety  devices  are  nevertheless  essen- 
tial to  guard  against  loss  due  to  accidents  with  the- attendant  delays. 
Safety  devices  on  VULCAN  Hoists  insure  complete  control.  No 
safety  devices  are  dependent  upon  the  operator's  will,  and  no  safety 
device  delays  the  operation  of  the  hoist. 

You  may  have  safety  requirements  to  consider  that  our  engineers  can 
help  you  on. 

VULCAN  IRON  WORKS 

Established  1849 
1748  Main  Street  -  Wilkes-Barre,  Pa. 

n 


Mr.  Switchboard  Manufacturer: -- 

Of  the  electrical  slate  used  in 
1920  in  the  United  States,  over 
10  percent  was 

Penrhyn  Purple 

actually  quarried  and  finished 
by  us.  We  list  among  our 
customers,  five  of  the  largest 
switchboard  manufacturers  in 
the  United  States. 

Is  not  this  a  guarantee 
of  service  and  quality? 

The  Penrhyn  Slate  Co. 

HYDEVILLE,  VERMONT 


The  Babcock  &  Wilcox  Co. 

85  Liberty  Street,  New  York 

HsTAHLisin-.o  1S6S 


Water  Tube  Boilers 
Steam  Superheaters 
Chain  Grate  Stokers 

BRANCHES 

Boston.  49  Federal  Street 

Philadelphia,  North  .American  Building 

Pittsburgh.  Fanners  Deposit  Bank  Building 

Clevelamd.  Guardian  Building 

Chicago.  Marquette  Building 

Detroit.  Ford  Building 

CIXCINNATI.  Traction  Biiildiug 

Atlanta.  Candler  Building: 

Tucson,  Ariz.,  21  South  .stone  .\ venue 

New  Orleans.  521-5  Baronne  Street 

Houston.  Texas.  Southern  Pacific  Building 

Fort  Worth,  Te.^..  Flatircn  Building 

Denver,  435  Seventeenth  Street 

Salt  Lake  City,  70,5-6  Keams  Building 

San  Francisco.  Sheldon  Building 

Los  Angeles.  404-406  Central  Building 

Seattle.  L.  C.  Smith  Buildii 

Havana,  Cuba,  Calle  de  Agi 

San  Juan,  Porto  Rico,  Ro 

HONOLUL 


-  104 


si^-V^r^^X- 

^KSCHENECTADY.^ 

^.c^LV-r*^ 

CD 

C 

INSULATING  VARNISHES 

EAR  &  BLACK   BAKING 
:LEAR   &  BLACK   AIRDRYING 
CLEAR  &   BLACK   OILPROOI 
FINISHING   WIRE   ENAMEL 

Inquiries  solicited. 

We  gladly  cooperate  in  the  solution  o 
insulation  problems. 

S. 
f 

Schenectady  Varnish  Company 

SCHENECTADY,  N.  Y. 

Please  mention  The  Electric  Journal  when  writing  to  advertisers 


December,  1921 


THE  ELECTRIC  JOURNAL 


33 


STEEL    P OLEO    Pole  Purpose 


Cut  shows  Bales  50  foot  Sleel 
Poles  in  senice  by  Gary  Heal, 
Ligbl  &  Waler  Co.,  al  Gary,  bdi- 
ana,  carrying  Iwo  heavy  3-wire  cir- 
cnils  and  a  ground  wire.  Several 
miles  of  litis  inslalladon  in  service 
evidences  the  hroad  range  of 
adaplabilily  of  Bates  Steel  Poles, 
lileraily,  we  make  sleel  poles  for 
every  pole  purpose. 

Bates  Steel  Poles  are  becom- 
ing universally  popular  world 
wide.  Repeat  orders  testify 
their  general  suitability  for 
every  Pole  purpose.  Telegraph, 
Telephone,  Power  Transmis 
sion,  Electric  Trolley  Lines, 
Electric  Lighting,  etc.  High- 
est class  and  most  up-lo-date 
steel  pole  equipment  in  the 
world.  Our  STEEL  POLE 
TREATISE  tells  the  story. 
Ask  for  it. 

About  2,000  tons  of  steel 
constantly  on  hand:  mmedi- 
ate  shipments  and  lowest 
prices. 

Tubular  Steel  Poles  cost  8W 
more  than  Bates  Steel  Poles, 
yet  Bates  Poles  are  100* 
stronger — will  last  100*  longer, 
cover  a  much  broader  range 
of  adaptability  and  are  much 
more  artistic  than  Tubular 
Poles.  Ask  us  to  verify  these 
facts. 

Bates  Expanded 
Steel  Truss  Co. 

08  So.  La  Salle  Street 


CHICAGO,  ILL 


ENDURANCE 

UNEQUALLED 
PRACTIGALLY  PROVEN 


^w 


LOWEST  UNIT  COST 
OF  OPERATION  POSSIBLE 

CENTRAL  STATION    CATERING 


MOHAWK 
BELTS 

are  particularly  efficient  for 

Electric  Drives 

They  stand  hard  usage 

and  cost  much  less   in 

the  long  run  than  any 

other  good  belt. 

Made   by 

Smyth  -  Despard  Co. 

UTICA,    N.  Y. 


MICA 

Soft  India,  all  grades,  sizes  and  quali- 
ties. Mica  Splittings 

MICA  PLATE 

Sheets   of   all  qualities   for  moulding 
and  commutator  work 


Absolute  accuracy  in  thickness  and  finish 


Prices  are  low 
Let  me  quote  on  your  requirements 


L.  Vandervelde 

(Late  D.  JAROSLAW) 

London    19  Tower  Hill    England 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


34 


THE  ELECTRIC  JOURNAL  ' 


Vol.  XMII,  No.  12 


AJAX 

INSULATING  VARNISHES 
AND  COMPOUNDS 

We  offer  to  the  Elortriral  Myniifart- 
urers  and  Repair  bhups  a  line  of  In- 
sulating Varnishes  and  Solid  Com- 
pounds com  I'leteiy  meeting  the  physi- 
cal and  electrical  requirements  of  all 
various  classes  of  electrical  apparatus. 
Complctt  I nformation  on  Request. 

THE  SHERWIN-WILLIAMS  CO. 

INSULATING  VARNISH  DEPT. 

601  Canai  Road  Cleveland.  Oh 


Trade  Mark   Reg.  U.  S.  Pat.  Office 

AMELECTRIC-PRODUCTS 


TROLLEY  WIRE 


BARE  COPPER  WIRE  AND  CABLE 


WEATHERPROOF  WIRE  AND  CABLE 


PAPER  INSULATED  UNDERGROUND 
CABLE 


MAGNET  WIRE 


GALVANIZED  IRON  AND  STEEL 
WIRE  AND  STRAND 


American  Electrical  Works 

PHILLIPSDALE,  R.  I. 


CINCINNATI  NEW  YORK 

Tractioo  BIdg.  233  roadway 


DETROrT" 

RUBBER  COVERED 

WIRES 


Rubber  Insulated 
Wires  and  Cables 

for  Every  Electrical  Purpose 

DETROIT  INSULATED 
WIRE  COMPANY 

Detroit,  Mich. 


DISTRICT  REPRESENTATIVES: 
CHICAOU:  W'm.  P.  Crockett.  411  S.  Jeflerson  St. 
BIFFAI.O:  L.  A.  Wooley.  Inc..  SJ-s.s  Elllcott  St. 
BIRMINOHAM:  Robertson  Supply  Co.     Inc. 
PHILADELPHIA  :  L.  P.  Clark.  249  N.  Uth  St. ' 
PITTSBtROH:  Davls-Cottrell  Co..  JJ2-JJ4  First  Ave. 
SAN  FRANCISCO:  Baker-Joslyn  Co..  71  New  MontKomery  St. 
LOS  ANQBLES  :  Baker-Joslyn  Co..  J30  Azusa  St. 
SEATTLE  :  Baker-Joslyn  Co..  S26  First  Ave.  South 


ALLOYS 

for  Electrical 

Resistance 


Nichrome 

Advance 

No.  193  Alloy 

Therlo 


Also  Pure  Nickel 

in  Wire,  Strip  and  Sheet 

Driver -Harris  Company 

Harrison.  IV Ew  Jersey 

Chicago         •         Detroit  -         Conada         '         Eajland         '        Fraace 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


December,  192 1 


THE  ELECTRIC  JOURNAL 


35 


ADVERTISERS 


Acme   Wire   Co 

American    Brass    Co 

American   Electric   Works    

American    Lead   Pencil   Co 

American   Rolling   Mill   Co 

Anaconda    Copper    Co 

Atkins  &  Co.,   E.  C 

Audel   Co.,   Theo    

Automatic    Eeclosing    Circuit    Breake 

B 

Babcock  &  Wilcox  Co.,  The    

Bakelite  Co.   General    ■ .  .  . 

Baker    &    Co 

Bates  Expanded  Steel  Truss   Co.  . .  . 

Benjamin   Electric   Mfg.    Co 

Benolite    Co 

Biddle,    James    G 

Bond,   M.   &   Co 

Borne    Scrymser    Co 

Brill,  J.  G.  Co.,  The 

Bussman   Mfg.   Co 

C 

Chalfonte    Hotel     

Chapman  El.   Works    

Continental    Fibre    Co 

Commonwealth   Edison   Co 

Corliss  Carbon  Co 

Crescent  Electric  Mfg.   Co.    

D 

Davis  Slate  &  Mfg.  Co 

Detroit   Wire   Co 

Driver-Harris   Co 

Dossert  &  Co 

E 

Electric   Trade   Publishing  Co 

Electric  Furnace  Construction  Co.  . 
Electric  Power  Equipment  Corp.  . 
Electric  Supply  Jobbers  Assn.  ... 
Electric  Engineers  Equipment  Co.    . 

Electrose  Mfg.   Co 

Enterprise    Electric    Co 


Galena   Signal   Oil   Co 26 

Gamewell  Fire  Alarm  Telegraph  Co 21 

General  Bakelite   Co 9 

Gurney   Ball   Bearing   Co 14 

H 

Holbrook  Rawhide  Co 

Hope  Webbing  Co 37 

I 

Imperial  Porcelain  Works    30 

Indiana  -Rubber  &  Insulated   Wire  Co.    .  .    36 


Klein   &   Sons,    Mathias    25 

L 

Leeds   &    Northrup    22 

Luminous    Unit    Co 

M 

McGraw-Hill   Book  Co 10,  14 

Manning   Paper   Co 37 

Martinique    Hotel    21 

Moloney  Electric  Co 27 

Morgauite  Brush   Co 23 

N 

National    Carbon    Co 25 

National  Fibre  &  Insulating  Co 8 

Norma  Co.  of  America,  The    3 

P 

Pelton  Water  Wheel  Co 27 

Photostat     Corporation     25 

Pittsburgh   Malleable  Iron  Co 24 

Penrhyn    Slate    Co 32 

Powell,   P.   W 24 


E 

Railway   &   Industrial  Engineering   Co.    .  . 

Robinson   Co.,   Dwight   P 37 

Roebling  Sons  &  Co.,  John  A 24 

Rome  Wire  Co 22 

S 

Sangamo   Electric    Co ; 12 

Scaifo,   Wm.  B.    Sons   Co 27 

Sargent  &  Lundy    37 

Schenectady   Varnish    Co 32 

Sherwin-Williams    Co 34 

Sidcbotham,    J 24 

Smith   Co.,    S.   Morgan    6 

Smyth-Despard    Co ;  .  .  .  33 

SKF    Industries,    Inc 38 

Specialty   Porcelain   Works    30 

Speer  Carbon   Co 31 

Spray    Engineering   Co 24 

Stackpole-Carbon    Co 31 

Standard  Underground  Cable  Co 36 

Stone  &  Webster    37 

Structural  Slate  Co 29 

T 

Texas   Co.,  The    15 

Toledo   Crane   Co 

U 

U.   S.  Electric  Tool  Co 28 

V 

Vandervelde 33 

Vulcan   Iron   Works    32 

W 

Wagner   Electric   Co 

Ward  Leonard  Electric  Co 19 

Waterbury  Button  Co 22 

Wellman,   Seward,   Morgan  Co.  " 6 

Westinghouse   Electric    &    Mfg.    Co.    .  .  17,  18 

Westinghouse   Lamp    Co 16 

Westinghouse   Traction   Brake  Co 11 


^«Pi^P9Mppil||| 


.BENOLITE  COMPANY. 

PmSBURGK.PA. 


\UHN»SHES  a  COATINGS 


B.N.X.ISOS 


Please  mention  The  Electric  Journal  when  writing  to  advertisers 


36 


THE  ELECTRIC  JOURNAL 


Vol.  XVIII,  No.  12 


Standard 

Cable  Junction 
Boxes 

insure  economy  in  the 
installation  and  mainten- 
ance of  electric  cable  sys- 
tems, permit  rapid  dis- 
connection of  branch  cir- 
cuits and  give  absolute 
protection  to  the  cable 
against  moisture. 
The  box  illustrated  is  a 
three  -  way  sectionalizing 
box  largely  used  in  mines 
and  designed  for  mount- 
ing on  the  wall  of  the 
mine  shaft.  The  main 
line  is  connected  solid 
through  the  box  and  the 
branch  cable  has  the  dis- 
connecting feature. 
The  clamps  which  protect  the  lead  nipple  and  enclose  the 
armor  wires  of  the  cable  and  hold  them  in  place  are  also 
shown  in  the  illustration. 

For  detailed  information 
write  our  nearest   office. 

Standard  Underground  Cable  Co. 

Pittsliurgh,  Pa. 


Boston  Atlanta 

New  York  Washington 

Philadelpliia  Detroit 

.Minneapolis 


Chicago  Los  .\ngeles 

St.  Louis  Salt  Lake  City 

Seattle  San  Francisco 

Kansas  City 


£«» iiiK tiiiit iiiliiiiMiiii mil Ill iiiiiiiii iiiiiii 


IF  IT'S 


PARANITE 


IT'S  RIGHT 


More  than  Code  requires 


For  30  Years  the  Standard 


RUBBER  COVERED  WIRES  AND  CABLES  FOR  ALL 

PURPOSES 

HIGH  TENSION  CABLES 

LEAD   COVERED   CABLES 

LAMP  CORDS,  SILK  AND  COTTON  COVERED 

PORTABLE  CORDS,   SILK  AND  COTTON  COVERED 

MINING  MACHINE  CABLES 

TELEPHONE  WIRES  AND  CABLES 

FIRE  ALARM  CABLES 

STARTING,    LIGHTING    AND    IGNITION    CABLES 

FOR  AUTOMOBILES,  MOTOR  BOATS, 

TRACTORS  AND  AEROPLANES 


Factory  and  General  Office 


Indiana  Rubber  &lnsulated  Wire  Co. 


JONESBORO,    INDIANA 


Chicago  Office 
210  South  Dcsplaines  : 


N«w  York  Office 
The  Thomas  &  Betts 
63  Vesey  Street 


WIRE  AND  CABLE 

for  Electrical 
Purposes 

Bare  Copper  Wire — Soft,  Medium 
or  Hard  Drawn 

Copper  Trolley  Wire 

and 

Stranded 
Transmission  Cable 


Magnet  Wire 

Round,  Rectangular  and  Square 


Insulated  Copper 
Wire  and  Cable 

Weatherproof  and  Slow  Burning  Insulation 


"K.K."  Weatherproof 
Line  Wire 

For  Electric  Light,  Electric  Railway, 
Telegraph    and   Telephone  Purposes 


Annunciator 
and  Office  Wire 


Pi  ice  lists  a>iJ  descriptive  pamphlets 
furtiished  upon  request 

The 

American  Brass 

Company 

Main  offices: 

WATERBURY,  CONNECTICUT 


Mills  and  Factories 


I  ANSONIA  BRANCH 

I  BUFFALO  BRANCH 

=  KENOSHA  BRANCH 

I  TORRINGTON  BRANCH  - 

I  WATERBURY  BRANCH   - 

fiiiiiiniiiiiiiiiii I iiiiiiiiliiiiiiiiiiiiiuiiiiliiiiiiilHlliiiiiiimiiiii 

Please  mention  The  Electric  Journal  when  writing  to  advertisers 


Aneonia,  Conn.  = 

Buffalo,  N.  Y.  I 

Kenoiha,  Wis.  | 

Torrington,  Conn.  = 

Waterbury,  Conn.  | 

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