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Electric Journal 




Copyright, 1922 by The Electric Journal 

Publication Office 




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 



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. 


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. 


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 


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

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

The Dual Drive Units — Ivan Stewart 


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 


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 


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 


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 ''*>•» 


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 


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. ^^^ 

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 


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 


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 


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 


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 


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 



The Electric Journal 




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






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: — 



3 Brakes 3 General . 



Materials — Insulation 3 

Measurements — Meters — Relays 3 

Theory 4 


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 



Rectifiers 6 

Rotary Converters 6 

Storage Batteries 6 

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



General — Systems 7 

Lines — Overhead — Underground — 
Conductors 7 

Switchboards — Interrupting Devices 
— Protective 7 

Regulation and Control — Regulators 
— Controllers — Rheostats 7 


General — Electrochemistry S 

Lighting 8 

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

Intelligence Transmission 9 


General 9 

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


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


(pp. 12-16) 


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 


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, 

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. 


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


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. 


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. 


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. 


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. 



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. 


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. 


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. 

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. 


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. 


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. 


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. 


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. 


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. 

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, 

For Forward and Reverse Power- QB. 1928. 

Constant with Current Transformer — QB, 

Transformer Connections — QB, 1934. 

Changing Dial Constants — QB, 2003. 

Reversal at Low Power-Factor— QB. 2074. 

Connections for Synchronoscope — QB, 2065. 

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. 


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. 


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


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. 


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. 


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. 




(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. 

Changing Motor to Generator — QB, 1760. 

Coil Shape— QB. 1803. 

Banding Wire— QH. 1806. 

Reconnecting 500 Volt for 125 Volt — QB, 

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


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. 


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. 


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


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. 


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, 

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. 


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. 


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


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

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

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. 


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. 

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

Alternating Current 


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, 

Amount of Ventilation— QB. 1717. 

Magnetic Center— QB. 1733. 

Efficiency of Water Wheel Generator— QB. 

Terminal Insulation— QB. 1767. 

Wave Form— QB. 1789. 

Reactance Coils to Protect Coupling— QB. 

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. 

Oiling System of Vertical Units QB. 1914. 

Eiliciency of Water Wheel Alternator — QB. 

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. 


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. 


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




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

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

Phasing Out— QB. 2056. 

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. 


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. 


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. 

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. 

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. 

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. 

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. 

Starting on eo^i Voltage— QB. 2064. 


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. 

Winding of Universal Motor- QB. 1734. 

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


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. 


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. 



Mercury Arc 

Reduction of Chargins Current— QB. 1958. 



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. 


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. 



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, 

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. 


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. 


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, 


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


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. 


Motor Capacity of Open Delta Connection — 
QB. 1904. 

Open Delta— QB. 1827. 


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. 


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


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. 


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

Grounding — QB. 1868. 


(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. 

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. 


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


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

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. 


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. 


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






(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 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. 


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. 



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. 


Nicholson Arc Suppressor — QB. 1956. 


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. 


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. 


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. 

Static Wires of Transmission Circuits— QB. 

Effect of Ground— QB. 1961. 


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. 


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

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. 


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

Current to Fuse Heavy Copper Wire QB. 

Expulsion Fuses — QB. 1790. 

Temperature Indicator— QB, 1867. 

(kneralor Fuses QB, 1883. 

Carbon-Tetrachloridc — QB, 2008. 


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. 


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. 




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. 


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. 


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. 


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. 


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. 

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 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. 


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. 


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. 


(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. 


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. 


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, 



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 


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. 

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. 



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. 


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, 

Generator for— QB. 1997. 


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. 

Magnetic Brakes— QB. 2029. 



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. 


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— 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. 






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. 



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. 

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. 


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. 


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. 


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. 

Stopping a Car by Braking with the Molars 

ROD. XVIII. 334. 

Shape of Car Wheel- QB. 1984. 


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 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. 


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. 


Turning Wheels— QB. 1709. 

Wrenches for Mine Locomolires— QB. 1841. 



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, 

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. 


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. 


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. 


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. 


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— 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. 




AIMUTIS. F. J. ^,„ ^ 

Armature Slot Wedges XVI: Dec, 

ABBOTT, S. H. , o- 

Exnerience in Drying Out Large Irans- 

foi-mers XVIU : Mar.. 


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., 


The Foundations of Modern Radio 

_ XVIII : Apr.. 


Manual Starters for Small Squirrel-Cage 

Induction Motors XVI: Dec.. 


The Regenerative Circuit XVIII: Apr.. 


Enameling in the Automobile Industry.... 

XVIII : Jan.. 

ARTZ, W. H. 

Electric Paper Machine Drive (E) 

XVIU : Mar., 


Removing and Replacing Railway Motor 

Armature Shafts XVI: July. 

The Bus. the Trackless Trolley or the 
Trolley Car for Light Traction— 

Which? XVH: Oct.. 


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

York - XVII: Oct.. 


Proposed Reorganization of N. E. L. A. 

XVU : May. 

Adjustable Speed Motors and Control in 

Finishing Plants XVIU: Nov.. 


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

Convention at Pasadena (E) 

XVII : May. 

Constructive Central Station Suggestions 

(E) - XVIII: May, 

The Design of Large Induction Motors... 

XVI: June. 

The Propelling Motors of the U. S. S. 

Tennessee XVIII: June, 


Continuous Wave Radio Receivers 

XVIU : Apr.. 


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. 

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

BOL/.E. R. A. 

Electrically-Heated Metal Pattern Plates 

on Molding Machines XVI : May, 


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.. 

Things to Consider in Handling the 

Public XVI : Oct.. 


Impu-se-Gap Lightning Arresters 

- XVI : Feb., 

Radio Arc Transmitters XVIII: Apr.. 

The Future of the Birney Safety Car (E) 

XVI : Oct.. 

Chemistry and Chemical Control in the 

Lamp Industry XVI: May. 


Stroboscopic Slip Determination 

- XVII : Apr.. 


Power System of the South Philadelphia 

Works XVI: Apr.. 

Local Associations for Organization Bet- 
terment XVI: Oct.. 

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.. 


The Development of Rapid Transit Lines 

(E) XVIII: Oct., 

494 Th6 Future Outlook for Large Urban 

Electric Railways (E) XVI: Oct., 

397 The Electric Railway and the Jitney (E) 

_ XVIII : Oct.. 

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., 

77 Installation and Maintenance of Auto- 
matic Substations XVIII: June. 


311 The Safety Car _ XVI: Oct.. 


Inspection and Maintenance of Direct- 
Current Car Control XVII: Oct., 

443 CARLSEN. C. J. 

Electrical Refrigeration XVII: Nov., 

Proposed Changes in the American Pat- 

488 ent System XVI: July. 


Electric Furnace Gray Iron 

227 JCVin: Sept.. 


Heat Balance Systems XVIII: May. 

609 CHUBB. L. W. 

The Foundations of Modern Radio 

242 _ XVIII : Apr.. 


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., 

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.. 

52 The Control Equipment for the Propell- 
142 ing Machinery of the U. S. S. Ten- 
nessee XVIII: June. 

419 Testing Insulators in Factory and Field 

XVn : Nov.. 


198 The Irrigation of the Desert 

XVII : May. 


165 Expanding Bronze Bearings 

XVII : Oct., 

,.,, The Best Plan for Operating Street 

'-" Railways (E) XVII: Oct.. 

Methods of Computing Ifachinery Foan- 
464 dations _ XVII: Sept., 


Post-War Industrial Reconversion (E).... 
_...XVI : Jan.. 

Starters for Small Induction Motors (E) 
_ _...XVI : Dec. 

The Electrification of Industry (E) 

XVIII : Jan.. 


The Problem of Mass Transportation (E) 

—XVIII : Oct.. 


Transformer Equipment for the Chicago. 

Milwaukee & St. Paul Railroad 

XVII : Jan.. 


Water Powers (E) XVI: May. 


Allowable Working Stresses in High- 
Voltage Electric Cables. _ 

„ XVn : July. 


Munition Work in PitUburgh (E) 

„_ XVI : Jan.. 

Radio— Its Future (E) XVIII: Apr.. 


Dad, the Inspector, on Co-operation 

XVI : Jan.. 


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 


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., 


Reducing Mechanical Difficulties with 

Motor-Driven Applicationa 

XVIII : 'Sept.. 


The Development of Fan Motor Wind- 
ings XVI: June. 


Mazda C Lamps for Motion Picture Pro- 
jection XVI : May. 

DICK. W. A. 

Regulation of Automotive Generators... 

XVI : Apr., 


The Handling of Cooper XVIII: Feb.. 


The Student Army Training Corps (E) 

XVII: Feb.. 


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.. 

Steam for Extinguishing Fires in Turbo- 
Generators XVI : May, 





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' 


May, 189 

May. 163 
XVIII: Oct.. 448 

A. M. 

'DUDLEY, rx. ..i. . , „ . .. „f 

Eeversing the Direction of Rotation of 

Sincle-Phase Motors .XVI : Feb.. 

Storage Batteries 


DUDLEY. S. W. . ^ ,. 

Air Brakes in Electric Traction.......^^^.. 

Enpineers Should Study Cost Accounting 



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 


The Manufacture of Ferro-Alloys in 

Electric Furnaces ^^.XVI : Sept.. 366 

The Regulation of Electric Furnace|^(E) ^^^ 


..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 ^^ 


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 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., 


Application of Theory and Practice to 
the Design of Transmission Line Insu- 
lators XVI: Jan.. 


The Sale of Stock to Customer 

"fI;^; R^e^r'sing Mill Drive in^thi. Coun- ^^^ 



"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™„^ 




GILMAN. R. E. , ,u tt « '5 

The Main Generators of the U. h. » 

Tennessee XVIII: June 


Methods of Computing Machinery Foun- 
dati " 


..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.. 


Substation Short-Circuits XVI ; Feb., 


Electric Controllers fo 


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.. 


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 

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- 


HILD. F. W. ^ . , , ,p. 

Hold Fast to the Fundamentals <b) 



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 


XVI: Oct.. 412 

of Motor 

Sixty Thousand Kw Turbine-Generator 
""installation at the T4th Street Station 
of the Interborough RaP'^^j^"^^"^'^* 17.^ 

The Problem of Street Con|estmn.. ....... ^^^ 


M°n 'Shie' and "Turtine-lpid Con- 
trol for the U. S. S. Tennessee....^_^.. ^^^ 



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 


..XVII: Dec. 567 

Steam' Turbines for Mechanical Drive 


Inherent Defects and Future Sphere of 

Usefulness of Electric Traction (EK-- 


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 


The Lafayette Radio Station^......-^^^-- jj^ 


The Transmission System of the West 

Penn Power Company XVIII. May. io» 

HUTCHINSON. W. M. . . „ . 


'^^llf Jjatro^fr&c Llght^ Association 


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 ■*■'" 


Increasing the Load witl 


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 ^^ 





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 


Encourage Young Engineers to Enter 

Railway Organizations (E) 

,„ XVIII: Oct., 449 


Notes on Large Steam Turbine Design 

. XVI : Jan., S3 


Notes on Industrial Lighting 

,„•■■■" XVII : May, 198 


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'; 


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 


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).. 


■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, 

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 


Shop Facilities for Maintenance of Rail- 
way Equipment XVIII: Oct., 464 

Motors for Textile Finishing Plants 

XVIII : Nov., 504 

The Thermal Storage Demand Watt- 
meter XVII: June, 253 

Continuous Wave Radio Communication 

XVIII : Apr., 124 


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 


Large Capacity Circuit Breakers 

, ■; -" XVI : June, 261 

Inverted Contact Circuit Breakers. . 

XVII: Feb., 78 


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, 


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 

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 


Secondary Conductors for Electric Fur- 
naces XVII : Sept., 422 


Electric Furnaces for Steel Foundries — 

With Historical Introduction. 

XVI : Sept., 360 

Electric Railway Passenger and Freight 

Transportation XVI: Oct.. 422 


Cleaning Surface Condenser Tubes 

XVIII : July. 313 


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 

The Technical Work of the .Vational 

Electric Light Association (E) 

XVIII : May. 161 


Illinois Pioneering in Public Relations 

(E) XVIII: Oct.. 445 


Municipal Railway Operation at Seattle 

XVI : Oct., 428 

The Primaries of Today the Second- 
aries of Tomorrow (E) 

XVI : May, 168 


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 


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 


Research and Manufacturing (E) . 

■ XVII : Apr.. 127 


A High-Frequency Generator for Air- 
plane Wireless Telegraph Sets 

„ - XVI: Apr., 140 

Power-Factor m Polyphase Circuits 

XVIII: Jan., 20 


Electricity in Motion Picture Studios 

XVII: May, 223 


Construction of Semi-Steel. Front-En- 
trance Side-Exit Cars XVIII: Oct.. 468 




Characteristics of Startlnp: and LiRhtinff 

Batteries of the Lead Acid Type 

XVI : All!-.. 134 


Electricity in the Textile Industry (E).... 

XVtll : Nov.. 485 


Manufacturing Scheme of the South 

Philadelphia Works XVI: Apr.. 122 


Efficiency of Adjustable Speed Motors... 

XVIII: Jan.. 11 


Service with the Safety Type Car 

_ XVI : Oct.. 426 


The Future of the Autobus as it Affects 

the Electric Railway (E) 

XVII: Oct.. 430 


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 

Modernized Plant of Prudential Worsted 

Co XVIII: Nov.. 489 


The Logical Unit for Comparinij Repair 
Costs of Electric Locomotives and 

Cars XVII: Oct.. 475 


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 

Installation of Switching Equipment for 

Synchronous Converter Substations 

XVIII : July. 329 


The Association of Iron and Steel Elec- 
trical Engineers (E) XVI: Sept.. 357 


The Stability Indicator XVIII: June. 280 


Copper — A Delicate Material 

XVII: Aug.. 320 


Testing Railway Control Equipment 

XVI : Mar.. 87 


Reducing Mechanical Difficulties with 

Motot^Driven Applications 

XVIII: Sept.. 408 


Interchangeability of S q u i r r e 1-Cage 

Rotors XVI: Nov.. 481 


Heavy Alternating-Current Conductors.... 

XVI : Aug.. 343 

Current Limiting Reactors Commonly 
Protect Both Service and Equipment 

XVII : June. 248 


Electric Dredging on the Yukon 

XVI: Mar.. 86 


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 


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 


Dealing with the Public and Employees 
(E) XVIII: Oct.. 442 


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 

A New Form of Standard Cell 

XVIII: Feb.. 65 

ROOT. F. S. 

The Central Station and the Textile Mill 

XVIII: Nov.. 487 


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 


Enlarging the Field for Remote Control 

XVII: Feb.. 39 

Methods of Protecting Electrical Equip- 
ments XVII: Oct.. 453 


The Relations Between Gases and Steel. 

XVII : Apr.. 161 

The Dry Cell Radio Vacuum Tube 

XVIII : Dec. 536 


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 


Transformers for Synchronous Convert- 
ers XVIII: Nov.. 518 


3000 Volt Current Collectors for the Chi- 
cago. Milwaukee & St. Paul Locomo- 
tives XVII: July. 278 


The Gyroscopic Stabilizer on the 

donia" XVIII : 


Multiple-Unit Train Operation 

XVII : Oct.. 457 


The Development of Our Water Powers 

(E) _.. XVIII: Dec, 523 

Developing Our Electrochemical Re- 
sources (E) XVI: Jan.. 3 


The Design of Induction Motors for Tex- 
tile Service XVIII: Nov.. 494 


Lubrication of Steam Turbine Bearings 

XVII : Mar.. 90 


The Significance and the Opportunities 
of the Central Station Industry (E) . 

XVI : May, 166 


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 


The Liquid Slip Regulator.. XVIII : Jan.. 37 

Industrial Electric Heating 

XVI : May. 188 


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 



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. 


Expansion of Railroad Electrification 

(E) XVI: Jan.. 

Chicago. Milwaukee £ St. Paul Electri- 
fication (B) XVII: Jan., 


Utility Credit and General Prosperity 

(E) XVI: Oct.. 


Conduction in Liquid Dielectrics 

-..- XVI: Aug.. 

Vacuum and Heat Treatment of Insulat- 
ing Materials _ XVII: Apr.. 


Allowable Working Stresses in High- 
Voltage Electric Cables XVII: July. : 


Post-War Engineering Problems (E) 

XVI : Jan., 

The Story of the Insulations. 

....- XVII: Apr.. : 

International Standardization (E) 

XVII: July, i 


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. : 


The Flow of Power in Electrical Ma- 
chines _ XVI: July. ! 

Why High Frequency for Radiation 7 

XVIII: Apr.. 1 


The Power Indicating and Limiting Aiv 
paratus for the Chicago. Milwaukee & 

St. Paul Railroad XVIII: Feb., 


The Manufacturer and the N. E. L. A. 

(E) -....- XVIII: May. ] 


Main Driving Motors for the Chicago. 
Milwaukee & St. Paul Passenger Loco- 
motives XVII: July. : 


Interconnection of Power Systems 

- XVII: Nov.. I 

Electrical Transmission vs. Coal Trans- 
portation XVIII: Sept.. ' 

The Induction-Type Frequency Changer,. 

XVII: Aug., ; 


Condensing Equipment and Oil Cooling 

System for the U. S. S. Tennessee 

— XVIII: June, ! 


Reminiscences of the Erie Electrification 

at Rochester XVIH : Jan.. 


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 


Electric Drive and the U. S. S. Ten- 
nessee - XVIII: June. ', 


The Gyro Stabilizer for Ships (E) 

XVIII: Aug.. 


Adjustable Laboratory Rheostats 

XVIII : Feb.. 

A New Form of Standard Cell _. 

XVIII : Feb.. 

Methods of Magnetic Testing 

XVIII: July. 316: Aug.. 351; Dec. i 


Automatic Speed Control for Sectional 

Paper Machine Drive XVIII: Mar.. 


Lighting without Hanging Ceiling Fix- 
tures — A Tendency in Modern Light- 
ing Methods XVI: May. 


Use of Mica Insulation for Alternating- 
Current Generators XVI: Mar.. 

What Are Safe Operating Tempera- 
tures for Mica Insulation ? 

XVI: Apr.. 


Winding Railway Motor Armatures 

XVII : Oct.. 


Calvert Townley. President American 

Institute of Electrical Engineers 

XVI : July. 



The Function of Regeneration (E) 

XVII: Feb., 39 

3T0FFEL, T. H. 

Freight Service on Electric Railways 

XVIII : Oct., 474 

Development of Airplane Radio-Tele- 
phone Set XVI: May, 211 


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 


The Function of the Load Dispatcher 

(E) XVI: Nov., 469 

The Transmission Ring of the Du- 

quesne Light Company XVIII: May, 211 


The Graduated Fare System (E) 

- XVI : Oct., 417 

The New Passenger Locomotives for the 
Chicago, Milwaukee & St. Paul Rail- 
road _ XVII: Mar., 84 


Public Understanding, Consideration and 
Appreciation Necessary for a Solu- 
tion of the Electric Railway Problem 

(E) XVI: Oct., 408 


Effect of Short-Time Overloads on Rail- 
way Motor Armatures XVII: Oct., 473 

Some Mechanical Causes of Flashing on 

Railway Motors XVIII: Oct.. 481 

The Automatic Electric Bake Oven. 

„ XVIII: July. 296 


Electrical Propulsion for Battleships (E) 

XVIII : June, 237 


The Thermal Conductivity of Insulating 

and Other Materials XVI: Dec. 626 


A Tribute to Albert Schmid 

XVII : Feb., 40 


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 


The Comparison of Small Capacities by 

a Beat Note Method XVIII: Aug.. 349 


City Traction Problems (E) 

XVI : Oct.. 409 

The Relation of the Electric Railway to 
the Community (E) XVIII: Oct.. 443 

Dynamotors and Wind-Driven Genera- 
tors XVI: May, 20B 

Mutuality of Interests in Practice (E).... 

XVI : Oct., 418 


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 


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 


Co-Operation Between Operators, Car 
Builders and Equipment Manufactur- 
ers (E) XVI: Oct., 421 


Education of Radio Engineers at Yale... 

_ XVIII: Apr., 149 


Three-Phase Four-Wire Distribution 

XVI : Mar., 99 

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 


Automatic HL Control for Boston Sur- 
face Cars XVI: Oct., 469 

The National Electric Light Association 

for 1919 (E) XVI: May, 163 


Service versus Fares (E) XVII: Oct.. 436 


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 

Public Utilities— A Diagnosis (E) 

XVI : Oct., 414 

The Trackless Trolley or Trolley Bus (E) 
_ XVIII: Oct., 439 


The Application of Adjustable Speed 

Main Drives in the Steel Mill 

XVII : Sept., 367 


Portable Electrical Equipment for Mo- 
tion Picture Photography 

XVIII : Feb., 71 


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 


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 


Remote Control by Radio....XVIII : Apr., 146 

Oil Current Breaker Arrangement and 

Switching Schemes for Steel Mills 

XVH: Sept., 402 

Substations for Reversing Mill Motors.... 

_ XVIII : Sept., 389 


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

Three-Wire XVIII: Jan., 15 


Renewal of the Catenary Construction in 

the Hoosac Tunnel XVIII: Mar., 84 

WOOD. L. A. S. 

Ornamental Street LightinB..XVII : May, 195 

The Automatic Electric Bake Oven 

- XVIII: July, 296 

Testing for Short-Circuit Currents with 

Miniature Networks XVI: Aug.. 344 

F\iel Burning Equipment of Modern 

Power Stations XVI: Feb., 65 


Electrification of the Central Limones, 

Cuba XVII: Oct., 477 

Individual Motor Drive for Spinning 

and Twister Frames 

_ XVni: Nov., 501 


Selection of Motors for Service Condi- 
tions (E) XVII: Oct., 434 


The Development of Magnetic Materials 

XVIII: Mp.r., 93 


Farm Line Business at a Profit to the 
Central SUtion XVII: Feb., 79 

The Electric Journal 


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 

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 


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 

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 



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- 

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 


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 



of the 



"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 


\'o\. XVIII, No. I 

the good will of the public ; hence, the necessity of cul- 
tivating and establishing the good will of each local 

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 

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 


Trend of 



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 


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 

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- 

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. 




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 

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 


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 


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- 

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. 


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 









Pounds Baked ...... 

Minutes for Dipping. . 
Minutes for Dripping 

Minutes Baking 


Lbs. Baked per Kw-hr. 
Min. Current was on 









1 1.8 




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 


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. 


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 


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 


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. 


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- 


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 


/ / 



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 


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 


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 


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. 


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 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. 


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. 


\'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, — • 

} 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. 







s'sl >. 

■- 3 

■ Outer VVii 
of Cable 




.■\ssuined for 





a - 





600 000 Giro. 


5/16" Cable, Or- 

30 Amperes 










dinary Steel. 

60 Cycles 

600 000 Circ. 


5/16" Cable, Or- 

lo Amperes 











dinary Steel. 

60 Cycles 

600 000 Circ. 


5/16" Cable. Or- 

30 Amperes 









dinary Steel. 

25 Cycles 


400 000 Circ. 


9/32" Cable, Or- 

20 Amperes 







dinary Steel. 

60 Cycles 


250 000 Circ. 


No. 6 B. W. G. Wire 

12.5 Amperes 









Ordinary Steel. 

60 Cycles 


150 000 Circ 


No. 8 B. W. G. Wire 

7.5 Amperes 









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. 

(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 

/?, + 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. 





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 























^ i.i 



























































» 75 100 IJS 1 
1 ' Amfferes 



5 2io 


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. 


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 



-^ — ' 




■ — -Saas 
















, . 


















ill] ! 



/i 1 .^J^ 

pr \/ 




' i i .^ 



' '>^ 



.K, = 4 



/ , 


1 * * 

1 1 T<in,u. 

1 ? lb IS .'i 


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 


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. 


Shunt Motor 

Compound Motor 

Series Motor 

Torque — lb. ft. 
R. p. m 



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... 



17 020 

18 080 
33 000 
14 920 


1160 575 
10.2 5.04 

















17 170 

18 080 
33 000 
14 920 











10 790 












10 330 






33 330 
29 840 


17 466 

18 080 
33 GOO 
14 920 





14 820 

11 560 


10 000 

10 610 

14 370 




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- 


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 








Compound Motor 













33 350 

29 840 












17 410 

14 920 






































33 350 

29 840 


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 






















33 330 
29 840 





17 370 

14 920 




14 620 












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 



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 


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. 


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- 


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 


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- 



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 



































irake; Hon 




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. 


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- 


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 

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^ ¥ 


I v/o 



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 


J r, E 


ain Autotransformer r '■* 

F. ^ , 


A B 



GRE.IlTER than I22.S 



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 autotr ansformer 

Kv-a transformed ~ 

•^•■i I 1-333 2I3 ^i 


-E, , 











1 Main 


totransformer ] 








necessary for the two-phase three-wire system. 
are three cases to be considered. 




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 transfor m ed 


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-) 


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 


2-23 I , £, 

£717+ £7+ °-7°7 - °-s IT 

Kv-a of parts required for teaser 
Kv-a transformed 

= 4^(i-o.8i6|;) 

- (9) 


I2 = 



1.732 £1 ' 

Substituting this value in equation 
(i) gives, — 

/m = h 1(0.707 — £;) + ;'( (0.707 


FIG. 2 

FIG. 3 

0.577 ~|)] 

= /. -yi ( 0.707 — £■ ) -1- (0.707 - 0.577 g; ) 



2-2^ £7' 

/r.. = /, •y I + 1.333 £T 

*In the Journal for May, 1919, p. 216. 


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), — 



Vol. XVIII, No. I 

Kv-a of parts required for main unit 
Kv-a transformed 

= o.i8i 



-Ji.333 — 2.23 -f I + 0.707 - 

Also, from equation (10), — 

Kv-a of parts requ ired for teaser i_ / 

Kv-a transformed 2 \ 


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 



For the Two-phase, Three-wire and Two-phase, Four-wire 



Percentages for 

Percentages for 

Total Percentages 














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 part s 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? 

For this case-=— = 2 and from equation (9), — 

Kv-a of parts required for main unit 

Kv-a transformed ~ 


— 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 



o.5J = o.: 

Kv-a transformed 



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 £: 






+ 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' 


-+ 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 ? 


For this case -=-= 0.5 and from equation (14), — 

Kv-a of parts re quired for main unit 

Kv-a transformed ~ 


+ 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 



1 — 


















' V 























\ ^ 






















Ratio of gi 


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- 

/X^iilcutlom €)if Steam Coniloiii^tir^-II 

Seieciion of sSize 


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 .. 






















1— . 


e , 






















per A 


gallons per 
of steam. . . . 

2 Total lbs 

:! Vac. 75° 

■1 Improvt'inont in vacuum.. 

n Per cent corr. at 5% per 

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. . 


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 


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- 



10 000 

100 000 

100 000 

100 000 










4 900 000 

8 750 000 




11 430 

20 400 

12 0001 

100 000 


13 000 

100 000 






10 000 


100 oool 




16501 2000 2300 

1 1 550 000 14 000 000 16 100 000 

$40301 $49001 $5620 

26 900[ 32 7001 37 400 




11 130 000 


25 800 










3 850 000 

6 340 000 

8 540 000 





14 800 

19 900 






$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 



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 
















— r 

Rauo GaBons per 


10 Squa/e Fo 



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 



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 


427 000 

13 000 

13 900 




1 197 000 



12 000 

14 400 




2 989 000 




15 000 




5 040 000 


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. 












$4000 $7000 $73001 $6630 

lari;er condenser, are set down and the excess found as 

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 



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 









s " 







1 , 


Q ' 






^^ Size 


ire Fe 




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 


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 















4 200 000 

8 050 000 

10 500 000 





18 800 

24 500 










1 113 000 

2 219 000 

3 241 000 







16 000 
19 200 


4 438 000 


10 520 




45501 48501 

6501 950 

4340 6330 


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 


\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 

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. 


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 


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 



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 

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 

.'\.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. 


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- 

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 


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- 


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. 


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- 

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- 

i'atts positive sequence 

Pozver-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 

real power positive sequence 
fowei -factor ^^^^ power pos. seq. -j- reactive power pas. seq. 


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- 


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 

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- 




llo actors 


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. 


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- 


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- 



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 ' 


1 i_ 











_J 1=^ 

' — 

J ^ 


Fig. 2 

A, B, C, 

Kg. 3 

Mac ii 

. \L^' 

Rg. 5 

Fig. 6 








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. 


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- 

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. 


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 


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. 


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 

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 



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 



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 


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 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. 


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 


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 



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. 


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 



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 


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. 9 — UPS OF 6o 

FIG. to — 150 DEGREE 

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 



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. 

Rotors of somewhat higher peripheral speeds can be 
built by resorting to the use of removable pole tips. In 























































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 


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 



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^ 


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 

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 


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 



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- 


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 



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 



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 


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- 


I'or giving a definite time to ;i 


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 



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 


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 


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. 


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. 


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 


C T, 

Or for series winding.- 
2 Vt K ,_ 
C T, 

F. = 



January, 1921 




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 


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. 


Pitch Winding — From Figs. 5 and 9 it is evident 





FIG. 4 — TWO 





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. 


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 



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 


S N . 

I J I I 



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 

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 


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 



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 


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- 

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 



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 






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. 



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- 





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 : — 


^'= 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 


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 





FIG. 18 — COIL 





FIG. 19 — COIL 





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. 



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. 



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- 


mum of less than 800 kw, with an average of about 500 

The liquid type .slip regulator and the contactor 



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. 


\\ 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. 


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- 

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 


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. 


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; 


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, impair the operation of an electric loco- 


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; ■ 




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 


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 



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 

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 

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 

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. 










at iloohosLOi' 

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 



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. 



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. 


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- 


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 



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 

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 


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. 


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- 



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. 


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. 

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. 


1956 — Nicholson Arc SuppRESsoR-What 
is the Nicholson arc suppressor, and 
how does it work? 


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 



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. 


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). 


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) 


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. 


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. 



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. 


Three general types of transition have been employed in 
railway control apparatus, as follows: — 


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. 


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 


Manager, Small Turbine Division, 
W'cstinghousc Electric & Mfg. Company 


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: — 

Stoker draft fans 

Boiler feed pumps 

Condenser pumps 

a — circulating 

b — air pump 

c — condensate 

Service pumps 


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 



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 



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 

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^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 



\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- 

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 



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. 


R. II. XliU TON 

Power Engineering Dopt., 
k\'cstinghousc Electric & Mfg. Co. 


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 


Rs^'y"'"^ kssNsX'^ Rxwws^ 

fe";r/-.^ \.,.A "^//y^A 

Kssx*-!''?] K^wxsxN UxssWN 



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- 



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. 


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 



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 


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 



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 



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 


T-T,si.,t,ne,- Cooverter Arm. 
l.aii.ioimei Wattless 

H. T. 

Line Wattless Kv-a. 



Boost Buck 

5S Boost 


5S Bucl<. 


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 


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 






^' ■ • 





















D) «t qurref^\ Vol|«c« 1 

" 1 


Convener .\rm. 

H.T. Line Wattless Kv-a 

Mag. React. 
Kv-a. Kv-a. 

Boost Buck 

5"; Boost Voltage SSI Buck. 



10% Lead 

10% Lead] 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- 


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 



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^ 


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. 


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- 


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 


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 




























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- 

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. 



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. 

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 



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 









Lamp Board 


200 to 1** 

Limited by lamps 

Non • inductive 

Capacity based 


easily renew- 
able elements 

on ten 32 cp 
carbon lamps 

Slide rheostat 


to max. 

Min. — 2 
Max. ^ 5000 

Z«ro temp. coef. 

wire 15 inch 

Comp. rheostat 


200 to 1 

Min. =1 

Max. z:^ megohms 


Special resistor 

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 

-LnnRnrm l '" 

Binding Post 

Metal Tufc« 

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. 


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 



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 


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 


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 
















Fit-ld Amperes 



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 





























5- \ 
































' \ 


1 6 

) ■ 8 

from 1 

•0 I 


160 1 
3n in lj)«Kr«s 


axis at a. Then, by dropping tlie perpendicular ah to 
cut the ellipse at h the reactive drop oh or X^ is ob- 

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 





' / 






^ rn 


















5 — '■ 


nt of 


y 6 
No-Lcjad Ex 

f — ' 

) 1 


*See "Regulation of Definite Pole Alternators" by S. H. 
Mortensen, Transactions A. I. E. E., February, 1913. 


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 

Typical .lloJay i^ojiiioccioj]^ '!( 


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 



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- 



Vol. XVIII, No. 2 


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- 


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 

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 







'd) (e) (1) 


(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- 


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 



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 ,^_ 


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 

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 




\'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 

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 




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 

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 



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. 


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- 


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. 


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- 

It is interesting to note that the cell contents pene- 
trate the high lead and basic oxide 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 

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. 


For constant laboratory use, stable portable cells 

Februan', 1921 



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- 



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. 


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. 


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. 


Vol. XVIII, No. 2 


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- 


"-0 01860 
■ jH.01850 


» i 





jdl No. 10 
ell Ko. 10: 

S-Cell m 106 

6.ciu N4 107 




a-ceii ^o 10 

4-Cell ^o. 10 

^ ^ 



?-fJ — 

















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. 


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. 


Such changes noted at the mercurj- sur- 
face as the hydrolysis and formation of basic 
the solution give an increase of' e.m.f; 


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 

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 



E. M. F 





















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 leads gives a very stable contact with the cell and is 
free from the high resistance effects which accompany 
untreated electrodes. 


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- 


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 

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 


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 



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 


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 


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 


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 



Industrial Dcpt., 
Westinghousc & Ml'g. O 


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 


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. 



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- 


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 


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 


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 



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 

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 

Volt age 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 — 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 



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 
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 
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 



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. 


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. 


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. 



Vol. XVIII, No. 2 


) 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. 


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. 

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. 
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- 

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. 
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. 
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. 

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 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- 

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 

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. 
]_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 


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 



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- 


Equipped with individual motor drive, using 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 



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 


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 


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 

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- 


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 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 

J Reduction Gear unit 
f Control Spe«d Changer 
DSection Frequency Generator 



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- 



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!^^.: , 


I M .}r Cornice Works, ,San Francisco 


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 

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- 


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 


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 


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 :- 


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. 

Power- factor of heaters -— — — = 98.5 percent. 

Power consumed for entire bake = 100 kw-hr. for 
4000 pounds metal baked. 

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 



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- 

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 



instances, and a renewal in about two years was indi- 

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 


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- 

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 



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 



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 


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. 


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, 


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 



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- 

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 


Power Engineering Dept. 
Wcstinghouse Electric & Mfg. Co. 


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- 

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 


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- 



Operating without me- 
chanical load with normal 


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 





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 


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 


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- 

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 


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 



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 


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. 



















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- 


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 


, — 




Normal ./votagt ' j %^i^ 

lb/ ' . Jt^ \ \ 


X j?/\ 




fi^ '^ 




1 1 









Field Atniperes 



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 



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^ . 


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 

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 ^^"^^ 



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 


Electric Internationa 


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 



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 


more— the hottest current being near the center of the 

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 


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 


Research Laboratory, 
Westinghouse Electric & Mfg. Company 


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 

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 



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 

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 



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. '^ 


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. 


.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 


^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 

coming an 
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 


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. 


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 



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 


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. 




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- 


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 





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 


Vol. XVIII, No. 3 

as determined by the setting of the current-control casting and the deposited material. This zone of hard 


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 


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 


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. 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. 


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 



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- 

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 


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 


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. 


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- 

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. 






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 









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 




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 


Multi Contact 


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 


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 





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- 



Connections shown are as viewed from the rear of the 

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- 

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. 


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 


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- 

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- 

Soino lyal)Oi' ^Coiulltuyiis M 






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. 


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. 


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 



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 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. 


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, 



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 

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 



©FIEP'^'ir^^^f^ Data 
FOR com. -.ATEOl^S 



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. 


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. 


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 


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 






*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. 



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 

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 




Our subscribere are invited to use Ibis de;>artmenl as a 
means of securing authentic information on electrical and 
mechanical subjects. Questions concerning general enRinecr- 
ing theory or practice and questions regarding apparatus or 
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. 

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 
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. 

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 

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 


March, 1921 



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. 

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 



/iT"^ , (i^ 


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. 



\o\. X\'in, No. 




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. 





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. 


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 

Date— Month, day and year. 
Why Removed— Give briefly reasons for removing the 

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. 
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. 


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. 



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; 



Anhaturf Put In 

Motor No \-2i-^ 


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. 


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 


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 
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 


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- 

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 

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 



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 

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 

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- 

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 

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 

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. 


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 


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- 

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 

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 



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 


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- 

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 

The signals from the Lafayette station as received 
at Cavite, Philippine Islands : San Francisco, Cali- 
fornia ; Balboa, Canal Zone ; 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 


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 

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: 


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 

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- 



SiT>;5in!iTiT< Sy^tora 

for Arc Trau-siiiiUoj^^ 


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 

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 





Disconnecting antenna and 
back shunt circuit for arc radio 

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 



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 

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 

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 

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 



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- 

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, 





the current will build up by resonance to a maximum 

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 


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 


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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1 1 1 









nil ill! I 


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in 1 

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nil mil 















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- 

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 




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. 



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 


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- 

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- 





























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 



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. 


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. 


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- 

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 

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, 

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 

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 came into extensive com- 
mercial use. Its chief claim to distinction is the fact 
that it Was the forerunner of the three electrode tube 

In placing a grid between the plate and filament of 
a Fleming detector, DeForest did far more than merely 


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 

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 

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 

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 


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 


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 


Employing two identical transformers, each having three 

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 


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 

April, 1921 



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 





































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 

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- 


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 


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" 

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- 


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 


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 


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. 


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. 



Vol. XVIII, No. 4 


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 


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 


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 



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 


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- 

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- 


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 



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 : — 


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 

April, 1 92 1 



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 

W\x'/ IIls^i yrDq((Oiiey tor .lladladon? 


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. 


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..- 

It is desirable, for the sake of the <-xamples co be 
taken up further on, to consider the electric field pro- 

(a) (b) (c) 



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 



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- 

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' 







FIG. 2 — EFFElT of .\1.\X\\E1.]. ^ 1>1M']..\CEMENT CURRENTS OX 

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. 


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. 


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. 


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 



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 







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. 


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 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 


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 
— 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 : — 


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 



^r^ /r^ 





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 


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 


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 





ICOCO Cycles per Second 

Saturation Curves 

t / 


' / 



/ // 





/ J/ 


irve S 



£[ .^ 


'/ .^ 




V ,^7 











0/ / 

J?" / / 




/ y / 






















Field Amperes 



Vol. XVIII, No. 4 






10000 Cj'clos per Second 

IrOn-Lo6s Tests 








Ciii^ c St 





/ / */ 







/j^ y^y^ 






Field Amperes 

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 

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- 


10000 Cycles per Secood 

Short-Circuil Tests 





















if . 


i / ss^y /y 









\ X 







Field Amperes 

April, 1921 



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 
§, > 
0.8 160 

0.7 145 


0.1 U6 


10000 Cj-cles (>er Stecond 

BegMlatiun Test at 10000 CycluB per Second 



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- 

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^ 


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 

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 

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 



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 



;.*- Detector 


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- 

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. 


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 

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 



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 


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. 


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- 


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 


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 



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' 


Filament Battery 

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- 

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 


: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 



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 


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- 

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- 


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 



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. 


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 L 


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- 

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- 


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 

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. 


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 



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 


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 

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. 



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 

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 


Of a high power radio station cciuippid with arc trans- 

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 



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- 

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 

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 


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- 


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- 

*Described by the iiivciitcr on page 114 of this issue. 



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 



Radio Kiifiiiioir, 
M' I'.lcctric & .Mig. CDiiiijaiiy 


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- 

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 



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 






10 -■ 

10 ■' 


10 ■ 


10 I-' 1 

Cable Telegraph 

Wire Telephone 


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 


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, 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 


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- 

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 


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 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 


\ 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 


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 

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- 

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 


; 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, 

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- 

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 


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- 

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{ 

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. 


\'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- 

■1 .'IJO 


































































^ (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 


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- 

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 

4 Ycars-36 Weeks Per Year— 9 Hou 

ii.\r-iJisTHiuurio.N OK nouns 

rs Per Week— Total Hours 1296, 




Shop Work 













Pattern Shop 







Algebra 34 



Machine Shop 


Algebra 54 


Geonu-lrv and 
Trig. 54 








D. C. 36 




D.C. andA.C. 




Problems 36 

D.C. andA.C. 



Problems 36 

A. C. 54 



Total H 

ours per 










Percent, of 

11. 1 









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 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.'' 


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 

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. 



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 

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 



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means of securing authentic it 

mechanical subjects. Questions concerning eeneral euRineer- 
ing theory or practice and questions regardmp 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 neccssar>' for 
a complete undersL.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 bv an expert and checked by at least two 
others, a reasonable length of time should be allowed before 
expecting a reply. 


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. 



Vol. XVIII, No. 4 


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. 



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. 


In order to take care of surface burns such as result from 
coming in direct contact with an electric arc or flash of any 


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 

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 

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 


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. 


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'--" 


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. 


The Electric Journal 


May. 1921 

No. 5 

The National Electric Light Association 


National Electric Light Association 

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 


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 


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- 



\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- 

Constructive Suggestions by a 
Past President 


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 

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 



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- 

The Utilities' Situation 


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- 

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 

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 

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. 



Vol. XVIII, No. 5 

The Manufacturer and the N. E. L. A. 


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 Technical Work of the National 
Electric Light Association 


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 

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 


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 



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 

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 

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 



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 


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- 



\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 


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- 

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 Pittsburgh Power Zone 


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