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Electrical ENGINEER'S
POCKET-BOOK:
A HAND-BOOK
OF VaSFUL DATA FOR ELECTRICIANS AND
ELECTRICAL ENGINEERS.
HORATIO Ar*FOSTER,
WITH tup: collaboration of eminent specialists.
FIFTH KDITION,
COMPLHTELT REVISED AND ENLARGED.
NEW YORK:
D. VAN" NOSTRAND COMPANY
1908.
•l,
/
I
GOPYRTGHTED, 1902, 1908, BY
D. VAN NOSTRAND COMPANY,
New York.
fStanbope f>rM«
F. H. GILSON COMPAKY
BOSTON. U.S.A.
PREFACE TO THE FIFTH EDITION.
In appreciation of the very cordial reception accorded
the earlier editions of this book, and in recognition of
the fact that vast changes and advances have occurred
in every branch of electrical engineering since the
original publication, the author feels called upon to
issue the present revised and enlarged edition.
The book as now presented, exceeds the previous
editions in magnitude by about 600 pages, while the
subject matter of every section has been either com-
pletely revised and brought up to date, or entirely
re-written. The aim throughout has been to supply
in exhaustive and condensed form, the data essential to
the engineer engaged in any of the branches of the vast
domain of electrical engineering. While our concep-
tion of the fundamental principles of electrical science
can of necessity have undergone no very considerable
alteration, those essential details which in effect con-
stitute the working data of the practicing engineer
have so altered and grown that books published only
a fe#¥ years ago are already obsolete. It is believed
that a stage in the progress of electrical engineering
standardization has now been reached wherein a com-
pilation such as the present can be accepted as embody-
ing the vital element to which future advances will
appear to a degree in the relation of superficial alter-
ations.
The original plan of dividing the subject into a
number of sections and having each revised by an
iii
181662
IV PREFACE TO THE FIFTH EDITION.
eminent specialist in that particular field has again
been followed. Aside from the easy accessibility
afforded, this plan of construction is valuable only
in proportion to the weightiness of the authorities
entrusted with the revision of the several divisions,
and it is confidently believed that a perusal of the
names heading the sections will lead to the conviction
that a more approved and authoritative organization
could not have been wished for. The several con-
tributors are widely known and recognized as among
the first of their respective specialties, and it is be-
lieved that the general average of excellence assured
by their collaboration surpasses that of any compila-
tion of the kind previously attempted.
Each section is complete in itself, but needless
repetition has been avoided by the free use of cross
references through the medium of the very extensive
index.
Attention is directed to the large quantity of new
matter, appearing for the first time in print, in the
several sections. In the section on Conductors, e.g.,
the tables of Inductance, Capacity and Impedance, will
be found new and original. Many sections, e.g.,
Street Railways, Photometry, Conductors, Lighting,
Roentgen Rays, etc., are pointed out as examples
of exhaustive though condensed presentation. The
mechanical section has been treated with the same care
and attention as the electrical.
The matter has been confined to the requirements
of the electrical trades and sciences, the inclusion of
the usual mathematical tables and data found in the
commonly used handbooks having been avoided.
These tables being easily accessible, and the present
PREFACE TO THE FIFTH EDITION. V
edition being already of great magnitude, this exclu-
sion will be appreciated.
An important feature of the present volume will be
found in the voluminous and studiously developed
index and table of contents. The index is as com-
plete as the limitations of manipulative facility will
permit, and is calculated to render the finding of the
particular phase of the subject sought a matter of
least possible labor. The table of contents is designed
to supplement and extend the use of the index, and in
conjunction with the marginal thumb-index will render
instantaneous the location of sections and subdivisions.
The careful and lengthy work of revision and search
leads the author to believe that the number of errors
cannot be large, and he ventures to express the hope
that readers discovering any will have the kindness
to bring them to his attention.
In conclusion the author begs to express his grati-
tude to the many contributors for their cooperation,
and to the publishers for their painstaking effort and
g^enerosity in making so handsome and substantial a
volume.
HORATIO A. FOSTER.
100 Broadway, New York.
June 1, 1908.
/
LIST OF CONTRIBUTORS.
Smbob. unto, inrtnunent. { J^'p^iSlS^"'*
M«URirem«nts { Sif.^&S'sheldJii.
1
Magnetic Properties of Iron
Electromagnets
Properties of Conductors .
Properties of Conductors
Carrying A.C. Currents .
Dimensions of Conductors
for IHstrlbution Systems .
Underground Conduit Construction.
Townsend Wolcott.
Prof. Samuel Sheldon.
> Harold Pender, Ph.D.
(Harold Pender, Ph.D.
Standard Symbols
Cable TMIng . ,
Dynamos and Motors . . .
Tests of Dynamos and
Motors
Alternating Current Ma-
chines
N.E. Contractors* Assoc.
Wm. Maver, Jr.
I Cecil P. Poole.
< £. B. Raymond.
E. B. Raymond.
Cecil P. Poole.
( W. S. Moody.
( K. C. Randall.
A.I.E.E.
The Static Transformer . .
Standardization Rules . . .
*^„* "****^' '°*'°: I ^' C- H. Sharp.
J. H. Hallberg.
descent
Electric Lighting, Arc
vU
VIU
LIST OF CONTRIBUTORS.
Illuminatitig Engineering
Electric Bailways
Electrolysis
Transmission of Power
Storage Batteries . . .
Switchboards
Lightning Arresters . .
Electricity Meters . .
Telegraphy
Wireless Telegraphy
Telephony
Electricity In the U. S. Army
Electricity In the U. S. Navy
Resonance
Electric Automobiles . . .
Electrochemistry and Elec-
trometallurgy ....
X-Rays
Electric Heating, Cooking
and Welding
Lightning Conductors . . .
Mechanical Section ....
" " Index .
Dr. C. H. Sharp.
'A. H. Armstrong.
C. Renshaw.
N. W. Storer.
Milton W. Franklin, ALA.
A. A. Knudson.
Dr. F. A. C. Perrlne.
Lamar Lsmdon.
H. W. Young.
B. P. Rowe.
E. M. Hewlett.
Townsend Wolcott.
{
H. W. Young. '
J. B. Baker.
Ghas. Thorn.
F. K. Vreeland.
J. Lloyd Wayne, 9d.
Grahame H. Powell.
J. J. Grain.
Lamar I^rndon.
C. J. Spencer.
j Prof. F. B. Crocker.
) Prof. M. Arendt.
Edward Lyndon.
{Max Loewenthal, E.E.
Prof. Alex. G. McAdie.
I W. Wallace Christie.
Index
Max Loewenthal, EJS.
SECTIONS.
Page
SYMBOLS. UNITS, INSTRUMENTS 1
MEASUREMENTS 66
MAGNETIC PROPERTIES OF IRON 89
ELECTROMAGNETS 108
PROPERTIES OF WIRES AND CABLES 131
PROPERTIES OF CONDUCTORS CARRYING A.C. CURRENT 238
DIMENSIONSOFCONDUCTORSFOR DISTRIBUTION SYSTEMS 260
STANDARD SYMBOLS FOR WIRING FLANS, N. E. C. A. . 290
UNDERGROUND CONDUITS AND CONSTRUCTION .... 301
CABLE TESTING 321
DIRECT-CURRENT DYNAMOS AND MOTORS 334
TESTS OF DYNAMOS AND MOTORS 378
ALTERNATING-CURRENT MACHINES 404
STATIC TRANSFORMER 443
STANDARDIZATION RULES A. I. E. E 501
ELECTRIC LIGHTING 528
ILLUMINATING ENGINEERING 584
ELECTRIC RAILWAYS 612
DETERIORATION OF METALS BY ELECTROLYSIS ... 852
TRANSMISSION OF POWER 864
STORAGE BATTERIES 872
SWITCHBOARDS 906
LIGHTNING ARRESTERS 980
ELECTRICITY METERS 997
TELEGRAPHY 1040
WIRELESS TELEGRAPHY 1066
TELEPHONY 1069
USE OF ELECTRICITY IN U. 8. ARMY 1123
ELECTRICITY IN U. S. NAVY 1153
RESONANCE 1216
ELECTRIC AUTOMOBILE 1224
ELBCrROCHEMISTRY AND ELECTRO-METALLURGY . . . 1229
X-RAYS 1248
ELECTRIC HEATING. COOKING, AND WELDING .... 1266
UGHTNING CONDUCTORS 1277
FOUNDATIONS AND STRUCTURAL MATERIALS 1289
STEAM 1327
WATER-POWER 1460
SHAFTING. PULLEYS, BELTING. ROPE-DRIVING .... 1481
MISCELLANEOUS TABLES 1499
POWER REQUIRED TO DRIVE MACHINERY 1616
INDEX 1633
ix
M
/
TABLE OF CONTENTS.
ELECTRICAL SECTION.
STMBOLSk UHrfS, nrSTRUMEMTS.
Page
Beetrieal Engineerins Symbols 1
Electrical Engineering Units 2
Symbols for Phymcal Quantities (Table) 6
latemational Electrical Units and Measurements 10
Equivalent Units. Energy and Work (Table) 12
(losed areoit Cells 14
Open Orcoit Cells 15
Dry Batteries 18
Standard Cells 19
Grouping of Battery Cells 19
(ialvanometerB 21
Reaistanoe Standards 30
Wheatstone Bridge 31
Water Rheostats 83
(SalTanised Iron Wire, Properties of 34
(Condensers 35
SpedBc Inductive Capacity of Gases (Table) 35
Spetific Inductive Capacity of Solids (Table) 36
Specific Inductive Capacity of Liquids (Table) 37
Specific Inductive Capacity 38
Ekctioroeters 40
VoitmetecB 40
Ammetera 41
i3eetro-Dynamometers 42
WattmelecB 42
Kdrin's Composite Electric Balance 43
Potentiometer 47
Inttruments and Methods of Determining Wave Formn 49
QMliograph 60
MBASURBMEIITS.
Qemeotary Latvs of Electrical Circuits 55
BflBstanoe Measurements 56
Bflsistanoe of Galvanometers 60
Bentanee of Batteries 60
Beastanoe of Aerial Lines and House C&rottits 61
Xi
;
XU TABLE OP CONTENTS.
E.M.F. Measurements 02
Capacity Measurements 63
Electromagmetie Induction 64
Coefficient of Self Induction 65
M^wurement of Self Inductance 66
Measurement of Mutual Inductance 67
Measurement of Power in A.C. Circuits 69
Testa with Voltmeter 74
E.M.F. of Batteries . 74
E.M.F. of Dynamos 74
Comparison of E.M.F. of Batteries 76
Resistance Measurement with Voltmeter 78
Resistance Measurement with Voltmeter and Ammeter , . 78
Measurement of Very Small Resistances 79
Measurement of Insulation Resistances 80
Measurement of Insulation Resistance of Dynamos 86
Measurement of Insulation Resistance of Motors 87
Measurement of Resistance of Batteries 87
MAGNETIC PROPBRTIBS OF IRON.
Data for (B-3C Curves (Table) 89
Permeability at High Flux Densities (Table) 91
Methods of Determining Magnetic QualHies of Steel an<l Iron ... 91
Permeameters 94
Core Losses 98
Hysteretio Constants for Different Materials (Table) 99
Hysteresis Loss Factors (Table) 99
Hysteresis Factors for Different Core Densities (Table) 1(X)
Hysteresis Tests 101
Hysteresis Meter 102
Eddy Current Factors for Different Ckire Densities (Table) 106
Specific Energy Dissipation in Armature C!ore 107
ELECTROMAGNETS.
Principle of Magnetic Circuit 109
Traction 110
Magnetisation and Traction of Electromagnets (Table) Ill
Winding of Electromagnets 112
Resistance of Magnet Wire at 140*^ F. (Table) 112
Relation between Wire Length. Siie and Turns per Volt (Table) ... 114
Correcting Length of Magnet Coil (Table) 117
Linear Space Occupieti by Single Cotton-Covered Wire (Table) ... 121
Linear Space Occupied by Double Cotton-Covered Wire (Table) . . 123
Alternating (Current Electromagnets 127
Heating of Magnet Coils ' 127
Law of Plunger Electromagnet 127
PuU and Ampere-Turn Factors (Table) 12g
TABLE OP CONTENTS. Xlll
PROPERTIES OF WIRES AND CABLES.
Page
TJnite of Resistance 131
Speoifio Resistance, Relative Resistance and 'Relative Conductivity
(TaUe) 132
Temperature Coefficient (Table) 133
Fhyneal and Electrical Properties of Various Metals and Alloys (Table) 134
Wire Gauces (Table) 141
Wire Strands 142
Fhyaeal Constants of Copper Wire (Table) 143
Effect of Admixture of Copper with Various Subntances (Table) ... 144
Copper Wire Tables 146
Tenile dtrength of (Copper Wire (Table) 156
Weight o£ Copper Wire (Table) 157
UDderwriters' Test of Rubber Covered Wires 161
Standard Rubber Covered Wire Cables 161
SUodard Conductor, National Electric Code, G. E. (Table) 162
^ledal Oeblee for Car Wiring (Table) ' 173
Xavy SUndard Wires (Table) 174
Paper Insulated Cables (Table) 174
(^mbric Insulated Cables (Table) 179
Telephone Gebles (Table) 188
Teksraph and Submarine Cables (Table) 189
JointB in Rubber Insulated Cables 190
Jointing Gutta-Percha 0>vered Wire 193
Ahiminom Wire (Table) 194
Ahmunum and Ck>pper Compared (Table) 195
Ccwnparative Cost of Aluminum and Copper for Equal Cond. (Table) 195
Comparison of Aliuninum and Copper for Equal Length and C]!on-
doctivity (Table) 196
ReslBtanoe of Solid Aluminum Wire 62% Conductivity (Table) ... 196
Stnnded Weatherproof Aluminum Wire (Table) 197
Dimensione and Resistance of Stranded Aluminum Wire (Table) . . 198
Aluminuzn for Higb Tension Transmission Lines 199
Iron and Steel Wire, Phyeical Constants (Table) 199
Double Galvanised Telegraph and Telephone Wires (Table) .... 200
GalTanised Signal Strand. Seven Wires (Table) 200
Ptopertica of Steel Wire (Table) 201
BeslBtanoe Wires, Spec. Res. and Temp. Coeff. (Table) 202
Gennan Silver 202
Resistances of German Silver Wire (Table) 203
Ibnganin 203
Electrical Properties and C!onstitution of Manganin (Table) 204
Dimeosions. Resistanoe and Wei^ts of Resistance Wires (Table) . . 204
ResBstance Ribbon. la la, C^xiality 206
Krapp's Resistanoe Wires (Table) 206
Renetanoee of Driver-Harris Resistance Wires (Table) 207
Ckirrent Ganying Capacity of Wires and Cables 208
Ckrrsring Capacity of Wires for Interior Wiring (Tables) 209
X17 TABLE OF CONTENTS.
Carrying Capacity of Rubber Insulated Cables (Table) 210
Heating of Cables in Multiple Duct Conduit 210
Watts Lost in Single-Conductor Cables (Table) 212
Current Carrying Capacity qf Lead-Covered Cables . 213
Fusing Effects of Electric Currents 217
Tension and Sag in Wire Spans 218
Calculation of Vertical Sag 222
Properties of Dielectrics 227
Dielectric Strength of Rubber 229
Dielectric Strength of Gutta-Percha 202
Dielectric Strength of Air 233
Puncturing Voltage of Mica (Table) 234
Minimum Sise of Conductors for High Tension Transmission .... 235
PROPERTIES OF CONDUCTORS CARRTHTG ALTERNATHfO CURRERTS.
Skin Effect Factors at 20^ F. (Table) 237
Self Induction and Inductive Reactance of Circuits 23S
Self Induction of Iron Wire 240
Self Induction of Solid Non-Magnetic Wire (Table) 241
Inductive Reactance of Solid Non-Magnetic Wire (Table) 242
Inductive Reactance of Loop of Three-Phaae Line (Table) 245
Inductive Reactance of Solid Iron Wire (Table) 248
Capacity, Capacity Reactance and Charging Current of Transmission
arcuitB formed by Parallel Wires 248
Capacity of Transmission Circuits formed by Parallel Wires (Tables) 252
Simple Alternating Current Circuits, Definitions 259
DDfBllSIONS OF CONDUCTORS FOR DISTRIBUTION SYSTEMS.
Kelvin's Law 261
Calculation of Transmission Lines 204
Effect of Line Capacity 264
FormuIsB for Ooes Section, Weic^t and Power Loss (Table) .... 265
Cross Section, Resistance and Reactance Factors (Table) 266
Capacity Susoeptanoe of Two Parallel Wires (Table) . 269
Numerical Examples of Calculations of Wiring Systems 271
Transmission Line of Known Constants 274
Transmission Line FormulsB (Table) 275
Parallel Distribution 277
Calculation of Ooss Section, Weight, etc., of Lines 277
diart and Table for Calculation of Alternating Current Lines .... 279
Determination of Size of Conductors for Parallel Distribution of Direct
Current ." 284
Transposition of Lines 285
Loss in Sheath of Three-Conductor Lead-Covere<l Cables 293
Bell Wiring 293
Gas Light Wiring 296
Wiring for Generators, Motors, Transformers, etc 295
Wiring for Induction Motors 296
Connections of Transformers for Wiring 297
TABLE OF CONTENTS. XV
STAHDARD SYMBOLS FOR WnUHO FLAHS AS AOOPTBD BT THE
HATIOHAL ELECTRICAL CONTRACTORS' ASSOaATIOH.
UHDBRGROUHD CONDUITS AND. CONSTRUCTION.
Page
Cost of Manholes in DolUre (Table) 302
Cost of Sewer ConnectionB in Dollan (Table) ... 303
Cbostant Cdst per Conduit Foot for Manholes in Dollare 304
Cbst of Paving per Square Yard in Dollars (Table) 305
Cost of Street Excavation per (}onduit Foot (Table) 306
Constant Cost per Conduit Foot in DoUara (Table) 306
Cost of Duct Material in Place (Table) 307
Cost per Conduit Foot in Gties (Table) I 307
Cndergiound Work at New Orleans (Table) 308
Boston Edison O). Construction 309
Itemixed Cost of Conduit (Table) 316
Eaiinukting Cost of 0>nduit (Table) 317
Estimating Cost of Manholes (Table) 317
Grouping of Ducts in Manholes 318
UoderRTOund Cables 319
CkUe Heads 320
CABLE TESTING.
loBolaaon Resistance Tests 321
Testins Joints of Cables 323
Capacity Teats of Cables 324
Locating Breaks by Capacity Tests 327
Locating Crosses in Cables 327
Locating Faults in C^les 328
Copper Resistanoe or Conductivity of Cables 330
Testing Submarine (}ables During Maqufacture and Layiiiic 331
Locating Faults in Underground Cables 331
High Voltage or Dielectric Tests of Cables 332
DIRECT-CURRENT DYNAMOS AND MOTORS.
NotaUon ... 334
Fundamentals 336
External Characteristics 337
MagneUc Distribution 340
Armatures 341
Armature Windings 342
Balancing the MagneUc Circuits in Dynamos 349
Heating of Armatures 349
Armature Reactions 350
Commutators and Brushes 351
Field Magnets 352
Cboiing Surfaces of Field Magnets (Table) 352
GTToetatie Action on Dynamos in Ships 352
Direct-Current Motors •■ 353
Lsooard's System of Motor Control 354
XVI TABLE OF CONTENTS.
Page
Three- Wire System for Variable Speed Motor Work 354
Practical Dynamo DesifEn 355
Armature Details 356
Armature Loeoee 358
Commutator and Brushes 361
Air Gap and Pole Face 363
Field Macneta 364
Dynamo Efficiency 370
Armature Slot Sices for Arranisement of Standard Wires (Table) . . 372
Trial Armature Coil Slot Depths (Table) 373
Trial Values for Minimum of Armature Coils (Table) 373
Trial Values for Maximum Turns per Coil (Table) 374
Trial Values for CurrentOarrying Capacity of Armature Conduotoie
(Table) 375
Barrel Armature Winding Constants (Table) 376
Average Magnetic Leakage Coefficients (Table) 376
Average Dynamo Efficiencies (Table) 377
TESTS OF DYNAMOS AHD MOTORS.
Temperature Tests 378
Overload Tests 381
Insulation Tests 381
Strain Tests 381
Regulation Tests of Dynamos, Shunt or Compound, and Alternators . 382
Regulation Tests of Motors, Shunt, Compound and Induction .... 383
Efficiency Tests of Dynamos 383
Core Loss Test and Test for Friction and Windage 383
Brush Friction Test 384
Separation of Core Loss into Hysteresis and Eddy Chirrent Loss . . . 385
Kapp's Test with Two Similar Direct-Current Dynamos 387
Electric Method of Supplying the Losses at Constant Potential . . . 380
Calculation of Efficiencies 391
Hopldnson's Test of Two Similar Direct-^^hirrent Dynamos 303
Fleming's Modification of Hopkinson's Test 394
Motor Tests 394
Test of Street Railway Motors 397
Tests for Faults in Armatures 402
ALTERNATING-CURRENT MACHINES.
Energy in an Entirely Non-inductive and Balanced Threc-Phase (cir-
cuit 405
Energy in Non-inductive Thrce-Phaae Circuits 406
Copper Loss in Armatures of Alternators 407
Compensated Revolving Field Alternators 409
Regulators for Alternating (Xirrent Generators 409
Alternating (Xirrent Armature Windings 410
Armative Reaction of an Alternator 414
Synchronisers 416
Inductor Tjrpe Synchroscope • 417
Note on the Parallel Ruiming of Alternators 410
• •
TABLE OF CONTENTS. XVU
Page
Byndironisins 421
Alternating Current Motors 421
Elementary Theory of the Polyphase Induction Motor 422
AnalsrticBl Tlieory of Polyphase Induction Motor 423
Speed of Rotary Field for Different Numbors of Poles and for Various
Frequencies (Table) 424
Slip of Induction Motors (Table) 426
Core of Stator and Rotor 426
Number of Sots in Field-Frame of Induction Motors (Table) .... 426
Rotor Slots for Squirrel Cage Induction Motors (Table) 427
Flux Densities for Induction Motors (Table) 427
Rotor Windings 429
^rnchronous Motors 430
Theory of Synchronous Motor 432
Dynamotors 434
Direct-Current Boosters 436
Rotary Converters 436
Value of Alternating Current Voltage and Current in Terms of
Direct Current (Table) 438
Cbnverter Armature Windings 441
QMinertion of Transformers and Rotary Converters 442
Oxrrent Densities of Various Materials 442
THE STATIC TRANSFORMER.
Gores of American Transformers 443
Tiansfonner Elquations 446
Features of Design 447
Insulation 447
Temperature 447
Efficiencies 453
Magnetic Fatigue' or Aging of 8teel and Iron 455
Change of Hysteresis by Prolonged Heating (Table) 457
Regulation 458
Onnparative Expense of Operating Large and Small Trausformers 458
P6wer Factor 468
Testing Transformer 459
Sparking Distances Across Needle Points 462
Transformer for Constant Secondary Current 462
Economy Coils or (>ompensators 463
Transformers for Constant Current from 0>nBtant Potential 464
General Electric 0>nstant Current Transformers 464
Reactaooe for Alternating (Xirrent Arc Circuits 466
iy>tentaaJ Regulators 467
Separate Circuit Regulators 469
Three-Phase Regulators 469
Three-Fhaae Transformers 470
Ratio of Transformation in Three-Phase Systems 471
Tiaosformer Connections 472
Sagle-Fliaae Transformer Connections 472
XVlll TABLE OF CONTENTS.
Two-Phaae Transformer Connections 473
Three-Phaae Transformer Connections 473
Arrangement of TransformerB for Stepping Up and Down for Long
Distance Transmission 475
Three-Phase to Six-Phase Connections 475
Methods of Connecting Transformers to Rotary Converters 476
Converter and Transformer Connections 477
Measuring Power in Six-Phase Circuits 477
Y or A Connection in Transformers 478
Grounding the Neuttal 478
Unstable Neutral 479
Rise of Potential 479
General Electric Company Mercury Arc Rectifiers 480
Westinghouse Mercury Arc Rectifier Outfits 481
Transformer Testing 482
Insulation Test 483
Core Loss and Exciting Current 486
Measurement of Resistance 486
Impedance and Copper-Loss Tests 487
Heat Tests 489
Regulation 491
Efficiency 498
Polarity 495
Data to be Determined by Testa 495
Methods of Testing Transformers 496
Specifications for Transformers 498
Rise of Temperature 498
Location of Transformeni 499
Transformer Oil 600
STAITDARDIZATION RULES OF THE AMERICAN INSTITUTE
OF ELECTRICAL ENGINEERS.
Definitions and Technical Data 502
Performance, Specifications and Tests 605
Voltages and Frequencies 522
General Recommendations 622
Appendices and Tabular Data 523
ELECTRIC LIGHTING.
Light and Laws of Radiation 528
Intrinsic Brightness of Different Sources of Light (Table) 529
Units and Standards of Light 530
Photometers 534
Incandescent Lamps 640
Distribution Curves 540
Current Taken by Various Lamps (Table) 642
Proper Use of Incandescent Lamps 644
Life and Candle Power of Lamps 644
Importance of Good Regulation 646
TABLB OF CONTENTS. XIX
Page
Guidle-Houn — Regulatioii of Lamp Values 646
VariatioD io Candle-Power and Efficdency 647
Lamp Renewals 647
Luzninosity of Incandescent Lamps 648
Metallised Carbon or Gem Lamps 649
Tantalum Lamps 649
Tan0rten Lamps 658
Effect of Caianges of Voltage 658
When and How Incandescent Lamps are Used (Table) 666
Tbtals of Averafce Oonsumption, Showing Yearly Consumption per
16-cp. Lamp Connected (Table) 655
ODof>er-Hewitt Mercury Vapor Lamp 658
Neni0t.lamp 662
Tests of Various lUuminants by National Electric Light Assn. . . . 664
Moore Vacuum Tube Light 665
Efficiency of Moore Tube 666
Are Lamps and Arc Lii^ting 668
CUasiBeation 61 Arc Lights 568
Open Are Lamps ^ . . 669
Hi^ Tension Lamp 570
Magnetite Arc Lamp 570
Flaminc Arc Lamps 572
Searchlight Projectors 675
Eodoeed Arc Lamps 575
Terts of Arc Light Carbons 577
Endosed Are Carbons 578
Sins of Oarbons for Arc Lamps (Table) 578
Carbou for Searchlight Projectora (Table) 579
Carbons for Focusing Lamps (Table) 579
(handle Power of Arc Lamps 579
Arc Lii^t Efficiency 580
Heat and Temperature Developed by the Electric Arc 581
Balancing Resistanoe for Arc Lamps on Constant Potential Circuit . 581
Street Lic:hting by Arc Lamps 582
light Cut Off by Globes 582
Trimming Arc Lamps 583
QXUMIRATIlfG ENGHfEERIlfG.
Intensity of Illumination at Various Points (Table) 586
Grafrfiic Illuminating Chart 587
Required Illumination for Various Classes of Service (Table) .... 589
Skvinff by the Use of High-Efficiency Lamps (Table) 589
Experimental Data on Illumination Values 592
CoefficieDts of Reflection 693
Comparative Values of Illumination and Efficiency of Various Methods
of Lifting (Table) 594
Interior Illumination 596
Data on Arc Lighting Installations in Operation (Table) 598
Illumination ^99
XX TABLE OF CONTENTS.
Page
Correct Use of Light 600
Dietribation of Li^t by iDcandescent Lamps 601
Concealed Lighting Systems 601
Illumination Intensity Required for Reading 602
lighting Schedules 608
Lighting Table for New York City 604
HouxB Artificial Light Needed Each Month (Table) 606
Humphreys' Lighting Tables 607
Hours of Burning Conuneroial Lights (Table) . 611
Graphic Lifting Schedule for London, Eni^and . . . ^ 611
ELECTRIC RAILWAYS.
•
Grades and Oirves 612
Systems of Operation 613
Car Equipments 613
Locomotives 614
Weights of Rails (Table) 615
Radius of Curves for Different Degrees of Curvature (Table) .... 617
GradesiifperCent. and Rise in Feet (Table) 617
Elevation of Outer Rail on Oirves (Table) 617
Equipment Tables 018
Durability of Railroad Ties (Table) 619
Paving 619
Estimate of Track Laying Force 619
Railway Turnout 620
Electric Railway Automatic Block Signalling 622
Requirements of a Signal System 623
Typical Automatic Two-Line Wire, Non-Interfering Block Signal . . 624
Distributed Signal Block System 627
Material for One Mile Overhead Line Street Railway (Table) .... 628
Estimated Cost of One Mile Double Track Overhead Street Rail-
way System 629
SUndard Iron or Steel Tubular Poles 629
Standard Pole Line Construction 630
Double Track Center Pole CJonstruction 631
Plate Box Poles 632
Tubular Iron or Steel Poles (Table) 633
Oibic Ointents of Wooden Poles (Table) 633
Average Weights of Various Woods (Table) 634
Dip in Span Wire 634
Side Brackets 635
Trolley Wire Suspension 637
Guard Wires 639
Catenary Trolley (Jonstruction for A.C. Railways 640
Properties of Galvanised Steel Strand Cable (Table) 642
Line Material per Mile of Tangent Track for Catenary Construction
(Table) 643
Staggering Trolley for Sliding Contact 644
Bracket Construction 644
TABLE OF CONTENTS. XXI
Span Gonstruetion 644
Hangers per Span for Tangent Track (Table) 646
Hangera per Span for PuJl-Off Curve Construction (Table) 647
Energy Consnmption 652
Cowtants for Determining H.P. of Traction (Table) 663
florae Power of Traction (Table) 654
Traction (Table) 655
Revolution of Wheels for Various Speeds (Table) 665
Fb«er for I>ouble and Single Truck Cars (Table) 656
Tractive Effort on Grades (Table) 657
Kilowatts on Grades (Table) 657
Bower Consumption, 25 M.P.H., 85-Ton Car (Table) 668
Number of Can on Ten Miles of Track, Various Speeds and Head-
ways (Table) 658
Effect of SSiape of Moving Body on Air Resistance (Curves) .... 659
Headway, Speed and Total Number oi Cars 660
Kles per Hour in Feet per Second and Minute (Table) 660
Rating Street Hallway Motora 661
Tractive Effort :..!... 661
Thtftive Coefficient 662
IVain Performance Diagrams 668
Aeoderation 664
Goostenction of Speed-Time Curve 666
Data for Distance-Time Carve (Table) 669
Data for Speed-Time Curve (Table) 671
Rating Railway Motors from Performance Curves 678
Hotor Capacity (}urve 676
Graphical Approximation of Energy for Electric Cars 679
Train Friction Curves 679
Speed and Energy Chirves 680
Motor Cbaracteristic Curves 685
Determination of Energy 706
Single-Phase A.C. Railway Motors . 707
G. E. C^o/s Hand Potential Control System 710
SUigle-FliBse Motor C^haracteristios 713
Weights of A.C. Motor Equipments 719
Comparative Weights 75 H.P. 4-Motor Equipments 719
High Speed Trials on Lake Electric Railway 719
Interurban Car Tests 722
Train Los (Tables) 723
Oomparison of Car Tests (Table) 724
PenonaJ Factor of Motormen, Local Runs (Tables) 724
Tests of Interurban Cars. Northern Texas Traction Co. (Table) . . . 725
Two Motors va. Four Motors per Caa (Table) 729
Railway Motors, Standard Sises and Ratings (Table) 729
Weights of Equipment, Control Apparatus, Car Wiring and Motors
(Table) 730
Torque and Horse Power (Table) 731
mcy Braking of Cars 731
XXn TABLE OF CONTENTS.
Page
Copper Wire Fuses for Railway arcuits (Table) 731
Approximate Dimensions of Electric Cars (Table) 732
Weight of Car Bodies and Trucks 734
Dimensions of Brill Cars (Table) . . . ' 737
Electric Locomotives 789
Installation of Electric Car Motors 745
Preparation of the Car Body 746
Installing Controllers 746
Wiring 746
Operation and Care of Controller 747
Diagrams of Car Wiring . . . ' 747
Equipment Lists 752
Controllers 753
Series Parallel Controllers 755
Electric Brake Controllers 755
Rheostatic Controllers 756
Dimensions of ControUera (Table) 757
Sprague G. £. Multiple Unit Control 761
Westinghouse Unit Switch S3«tems of Multiple Control 766
Approximate Rates of Depreciation on Electric Street Railways . . 770
Depreciation of Street Railway Machinery and Equipment 770
Car Heating by Electricity 770
Track Return arcuit 771
Type of Bonds 772
Welded Joints 778
Resistance of Track Rails (Table) 770
Relative Value of Rails and Bonded Joints 780
Ingredients of Rails Under Test (Table) 780
Board of Trade Regulations for Great Britain 781
Calculation of the Overhead Conducting System of Electric Rail-
ways 785
Continuous Current Feeders Load Determination 780
Economical Design of Feeders 786
Limiting Potential Drop 788
Two Classes of Feeders 788
Calculation of Dimensions of Conductors 791
Drop and Loss in Line Between Two Substations of Unequal Poten-
tial 794
Impedance of Steel Rails to Alternating Chirrent 795
Experimental Determination of Impedance of Steel Rails 795
Experiment on Inter works Track of Westinghouse E. and M. O). . . 796
Comparative A.C. and D.C. Resistance Trolley and Track per Mile
of Circuit 798
Tests of Street Railway Circuits 798
Tests for Drop and Resistance in Overhead Lines and Returns . . . 798
To Read the Ground Return Drop Directly 799
To Determine Drop at End of Line 800
To Determine the Condition of Track Bonding and the Division of
Return Current 800
TABLE OP CONTENTS. XXIU
Page
Teiting Rail Bonds 801
Street Railway Motor Teating 803
Dnw-Bar Pull and Efficiency Test without Removing Motor from
Ckr 803
Testing Drop in Railway Circuits 804
Street Car Faults and Remedies 805
Wiring Diagrams for Lighting (Srcuits on Street Care 800
Special Methods of Distribution 807
Three- Wire System 807
Booster System 807
Retom Feeder Booster 808
Beetric Railway Booster Calculations 809
Series Boosters for Railway Service 813
Sbbstation System 814
Fbrtable Substations 819
Tlard Rail Systems 821
Rentanoe of Rails with Varying Composition 821
Beetrical and Chemical Qualities of Steel for Third Rail (Table) . . 822
Wrought or Refined Iron for Third Rail (Table) 824
Resistance of Steel, Variation with Manganese (Table) 825
Resistance of Steel. Variation with Carbon (Table) 826
Reristance of Steel, Influence of Carbon (Table) 826
Renstance of Steel (Table) 827
Location of Third Rail 830
Third Rail Insulators 831
Third Rail Shoe 832
New York Central Third Rail 834
Estimated Cost of One Mile Single Track Protected Third Rail. Approxi-
mate 836
Conduit Systems of Electric Railways 835
Sorfaoe Contact or Electro-Magnetic Systems 840
Westini^ouse Surface Contact System 841
Sectional Rail Construction S46
(jencral Electric Contect Railway System 847
DSTERIORATION OF UKDERGROnND METALS DUE TO
ELBCTROLTTIC ACTION.
Destnietive Effects 853
locrease of Current Flow upon Mains Due to Bonding same to Rails
or to Negative Conductors 856
eminent Movements upon Underground Mains 858
Beetrolytic Effects upon Water Meters 855
Dancer from Fire or Explosions 858
Qectrolysis in Steel Frame BuikHn^B 859
Current Swapping 859
Ahemating Chirrent Electrolysis 860
Insulating Joints in Mains 861
Surface Insulation 862
Summary 863
XXIV TABLE OP CONTENTS.
TRAHSMISSION OF POWBR.
Engineoring Features 804
Relative Efficiencies of Various Traosmiasion Methods (Table) . . . ' 8S5
Special Features of Design Due to Transmission Line Requirements . 868
Motive Power 807
Storage Reservoirs 867
'Generators 870
Transmitting Apparatus 870
Transformers 871
Pole Lines 871
STORAGE BATTERIES.
Theory and General Characteristics 872
Voltage 874
Types of Plates 874
Capacity 874
Discharge Rate Curve 876
Voltage Variation 876
Electrolyte 877
Cadmium Test 878
Polarisation 879
Efficiency 879
Comparison of Plants and Pasted Rlectrotien 880
Charging 880
Removal from Service 881
Battery Troubles 881
Testing 882
Weight of Complete Cell and Component Parts 882
Dimensions 883
Rates of Charge and Discharge 883
Capacity at Various Discharge Rates 883
Voltage Curves 883
Internal Virtual Resistance 883
Variation in Density of Electrolyte 884
Loss of Charge with Time 884
Efficiency at Various Char^re and Discharge Rates 884
Erection of Battery 884
Usee of Batteries 886
Methods of Controlling Discharge 889
End Cells and Switches 890
Counter E.M.F. Cells 891
Resistance Control 891
Shunt, Automatic, Reversible and Non-Reveraible Boosters 891
Comparison of Boostere 897
Installations 897
Three- Wire Sj^tems 899
Battery Capacity 900
Strength of Dilute Sulphuric Acid of Different Densities (Table) . . 904
TABLE OP CONTENTS. XXV
Page
Oooductinc Pbwer of Dilute Sulphuric Aoid of Different Strengths
(Table) 905
GDnducting Power of Acid and Saline Solutions 906
SWITCHBOARDS.
Design of Direct-Oontrol Panel Switchboards 906
Copper Bar Data (Table) 911
Alaminum Bar Data (Table) 911
Altematiiig-Current Switchboard Panels 912
Equipment of Single-Phase Feeder Panels 916
Equipment of Three-Phase Feeder Panels 917
Equipment of Two-Phase Feeder Panels 918
Equipment of Induction Motor Panels . '. 918
Equipment of Three-Phase Synchronous Motor Panels 919
Equipment of Three-Phase Rotary Converter Panels 919
Equipment of Constant-Current Transformer Panels 922
Are Switchboards 922
Direct-Current Switchboard Panels 924
Hsod-Operated Remote-Control Switchboards 928
Central Station Electrically Operated Switchboards 928
GrcumstanceB which Indicate the Necessity of Installing Klertrically
Operated Switchboard Apparatus 929
Hydro-Electric Generating Station Design 930
Bos-Bar and Bus-Bar Structures 933
(Seneral Arrangement of Switchboard Devices 935
Isolation of Conductors ' 936
Cdfa for Voltage Transformers 988
Hig^-Tension Conductors 939
Cbntrolling and Instrument Switchboard 940
Sabntataon Switchboard Equipments 942
Switchboard Instruments and Meters 945
Method of Figuring Instrument Scales ' 946
Brief Guide for Writing Switchboard Specif! cations .947
Switching Devices 948
SfMridng at Switches .948
CSrrait Breakers 949
Circuit Breaker Design 952
A.C. Ser\ice Circuit Breakers 952
Capacity of Circuit Breakers f Dr D.C. Generators 955
Cireuit Breaker Adapted for Motor of Given Size (Table) 955
Sgnalling Relays 955
Regulating Relays 956
Protective Relays 956
Applieation of Relays 960
Lever Switches 963
Plug Tube Switches 966
Disconnecting Switches 965
SvitdiM for High Potential 967
Westinghouse Oil Circuit Breakers 969
Oil (Srcuit Breaker Controller 975
General Electric Oil Switches 976
{
XXVI TABLE OF CONTENTS.
I lighthing arresters.
Li^tnins Protection Q80
Switching Q80
Cables 981
Engine or Water Wheel Governor Troubles 081
Protection Against Abnormally High Potentials on A.C. Circuits . . 981
Use of Reactive Coils 982
Use of a Protective Wire 982
Ground Connections 983
Lightning Arresteis 983
Lightning Arresters for Direct Current 984
Lightning Arresters for Alternating Current 987
Non-Arcing Metal Lightning Arrester 989
Garton Arrester 990
S.K.C. Arrester 990
Static Discharges 992
Arresters for High Potential Circuits 993
Low Equivalent A.C. Lightning Arrester 994
Horn Type 995
ELECTRICITY METERS.
Action of Integrating Meters 997
• Direct-Current Commutator Type Meters 997
Thomson Recording Wattmeters 998
Westinfi^ouse D.C. Int^n^ting Meters 998
Duncan Meters 998
Induction Type Alternating Current Integrating Meters 999
Wattmeters on Inductive Circuits 1000
Power Factor Compensation 1002
Minimizing Effect of Voltage Variation 1002
Westinghouse Single-Phaae Induction Wattmeters 1003
Wflstinghouse Polyphase Induction Wattmeters 1003
Thomson Hig^ Torque Single-Phaae Induction Wattmeteni .... 1005
Thomson Polyphase Induction Wattmeters 1005
Sangamo D.C. Integrating Meter 1006
Elementary Diagram of Sangamo D.C. Meter 1007
Sangamo A.C. Meter 1008
Wright Discount Meter . 1008
Meter Bearings, Registers and Commutators 1009
Prepayment Wattmeter 1010
Integrating Wattmeter Testing 1013
Testing Service Meters 1015
Calibration Data for Westinghouse Integrating Wattmeters (Table) . 1016
Testing Meters for Accuracy on Inductive Loads 1018
Method of Testing Service Meter for Inductive Load Accuracy ... 1019
Obtaining Inductive Load from Two-Phase Circuits 1019
Obtaining Inductive Load from Three-Phase Circuits ...... 1020
Testing Meters 1020
• «
TABLE OF CONTENTS. XXVll
Page
Tntiog Fblyphase MeteiB 1020
Standards for Testins Polyphaoe Meters 1020
Senrioe Goniwetions of Polyphase Meters 1023
Practical Methods of CSiecking Conneotions of Polyphase Meters . 1026
Meter Testing Formula) 1028
Formula for Testins the Shallenberger Ampere-Hour Meter .... 1028
Testing Formula for Shallenberger and Westinichouse Integrating
Wattmeters 1028
Testing Constant of Westinghouse Meters 1029
Westinghonse Direct-Current Meters 1030
Table of Testing Constonis for G. E. Co.*8 Meters 1030
* D3 '* Fblyphase Meters 1081
Formula for Testing Duncan Recording Wattmeters 1031
Table of Duncan Constants " K " and Watts per Rev. per M ... . 1031
IVr cent Error Table for Fifths of a Second 1032
Table Values of Constants for Fort Wayne Single-Phase Meters . . 1083
Formula for Testing Sangamo Wattmeters 1035
Tables of Constants for Sangamo Wattmeters 1035
Graphic Recording Metere 1036
Bristol Recording Meters 1036
General Electric Graphic Recording Meters 1037
Westin^ouse Graphic Recording Meters 1037
Action of Meters 1039
TELEGRAPHY.
Amoican or Closed Circuit Method 1040
European or Open Circuit Method 1040
Repeaters 1041
Umiken Repeater 1041
Gbegan Repeater 1042
Weiny-Phillipfl Repeater 1043
Duplex Telegraphy 1044
Dupleac Loop System 1047
Half-Atkioaon Repeater 1048
Doplex Repeater 1049
Steam Duplex 1050
Qnadruplex 1051
Tdegrai^ Codcfl 1062
WIRELESS TELEGRAPHY.
Electrical Oscillations 1055
E3eetromagnetic Waves 1055
Antenna 1058
Cbheicr 1058
Syntonic Signalling 1059
Skin Effect 1061
Tranmitten , • • • ■ 1062
Reeeivers 1064
Detectors 1066
Undamped Ownllations 1068
XXVUl TABLE OF CONTENTS.
TELEPHONY.
tleoeivera 1070
Transmitteni 1071
Induction Coil 1074
Hook Switch 1075
Calling Apparatus 1075
Series and Bridging Systems 1076
Polarised Bell 1078
Construction of Magneto Generator 1076
Factors Affecting Transmission: Inductance, Capacity. Resistance . 1079
Earth Currents, Induction, Cross-Talk 1081
Metallic arcuits 1081
Open Wire arcuits 1082
Cables 1082
Sample Specification for Telephone Cables 1083
Capacity of Aerial Telephone Cables (Table) 1085
Capacfty of Underground Telephone Cables (Table) . 1086
Sises of Cables (Table) 1086
Annual Expenses of Telephone (tables 1087
Lii^tning Arresters 1087
Classification of Telephone Lines 1088
Central Office 1089
Requirements of Satisfactory Operation of Switchboard 1089
Small Switchboards 1089
Multiple Switchboard 1090
Busy Test 1091
Series-Multiple Switchboard 1093
Branch Terminal or Bridging System 1003
Transfer Systems 1094
Relative Value of Multiple and Transfer Systems 1094
One Central Office va. Several 1094
Tninking 1095
Method of Operating Circuit Trunks 1096
Auxiliary Trunk Signals 1096
Ring Down or Common Trunks 1096
Common Battery System 1096
Rudimentary CJommon Battery Circuits 1097
Lamp Signals 1098
Circuits of Common Battery Switchboards 1098
Three-Wire System 1099
Two- Wire System 1101
(>onunon Battery Instrument Circuits 1102
Party Lines 1102
Selective Systems 1102
Method of Obtaining Impulse Currents 1103
Ontral Office Apparatus Auxiliary 1104
Automatic Exchange Systems 1105
Simultaneous Use of Lines 1105
Limits of Telephonic Transmission 1107
TABLE OF CONTENTS, XXIX
P»g«
NotM on Cost of Telephone Plant 1108
Private Linee, Intereommunicatins;, and House Syatems 1108
Common Return Intercommunicatinic Systems 1114
Tiro-Wire Intereommunicating Telephone Systems 1120
USES OF ELECTRICITY IN THE UNITED STATES ARMY.
SesrehUgfats 1123
Data ReiaUve to SeaKhttghts (Table) 1127
Rniaii0§ Chronograph 1128
Sehuits Chronoeoope 1130
Schmidt Chronograph 1131
Sqnire-Crdkore Photo-Chronograph 1133
Manipulation of Coast-Defenae Guns 1134
Electric Fuses 1134
Defensive Mines 1137
Fortress Telephones and Telegraphs 1140
Field Telephones and Telegraphs 1140
Telautograph 1141
Wireless Telegraphy 1145
Electric Ammunition Hoist with Automatic Safety Stop 1147
XightSi^ts 1148
Firing Mechanism for Rapid Fire Guns . . .• 1140
ELECTRICITY IN THE UNITED STATES NAVY.
General Requirements 1154
Engine 1154
Typical Results of Tests on Generating Sets (Table) 1150
SpedficatiooB for Turbo-Generator Sets 1 150
Turbine llflO
(jenerator 1161
Operation of Generator 1162
Steam Piping 1163
Switchboardb 1168
Doable Dynamo Rooms 1166
Wiring Specifications 1167
Single Conductor (Table) 1160
Twin Conductor (Table) 1170
Methods of Installing Conductors 1170
Lighting System, Lamp Specifications 1171
U. S. Navy Standards for 100-120 Volt Lamps (Table) 1176
U. S. Navy Standards for 200-250 Volt Lamps (Table) 1177
Valves for Navy Special Lamps (Table) 1178
Diving Lanterns 1 179
Searchlights 1179
Signal Lights 1181
ArdoM System 1181
Track Lights 1181
Power System 1188
XXX TABLE OF CONTENTS.
Tests 1184
Principal Requirements for Controlling Panels 1185
Tarret-Turnins Gear 1187
Ammunition Hoists 1191
^^ ft
Endless Chain Ammunition Hoists 1102
Boat Cranes 1194
Deck Winches 1196
Ventilation Fans 1196
Water-Tight Doors 1198
Steering-Gear . 1200
Interior Communication System 1202
Range Indicators 1204
Revolution Indicators 1204
Telephones 1206
Fire Alarms and Call Bella 1210
Range Finder 1211
Speed Recorder 1211
RESONANCE.
Formula for Alternating Current Flow 1217
THE ELECTRIC AUTOMOBILE.
Resistance Due to Gravity and Power Required 1224
Resistance to Traction on Common Roads (Table) 1225
Tires 1226
Motors 1227
Batteries (Tables) 1227
Rules for Proper Care of Batteries 1228
ELECTROCHBMISTRT-ELBCTROMETALLURGT.
Electrolysis 1229
Resistances of Dilute Sulphuric Acid (Tabic) 1229
Resistances of Copper Sulphate (Table) 1231
Resistances of Zinc Sulphate (Table) 1231
Applications of Electrochemistry 1231
Electrolytic (3iemistry 1231
Electrotyping 1233
Electroplating 1233
Electrolytic Refining of Copper 1235
Production of Aluminum 1239
Production of Caustic Soda 1239
Production of Metallic Sodium 1241
Potassium Chlorate 1242
Electrothermal Chemistry 1244
Calcium Carbide 1245
Manufacture of Graphite 1245
Electric Smelting 1247
TABLE OP CONTENTS. XXXI
X-RAYS.
Page
Tabet 1240
lUteoorative Tube* 1251
Eacdtinc Source 1252
Intemipten 1253
FIuorasoopeB 1266
BLRCTRIC HBATQIO. OOOKIHO AND WBLDIKG.
Variout Methods of UtUixinc the Heat Generated by the Electric
Corrent (Table) . . ; 1256
Equivaleat Vahiee of Eleotrieal and Mechanieal Unite (Table) . . . 1258
Oist of Electric Gookin« 1259
(}Qat oi Heatinc Water to Different Temperatures at Various Rates
for Current (Table) 1259
Eflideacy of Electric Cooking Apparatus 1260
Qxnparative Costs of Gas and Electric OmUdk 1260
CbmparisoD between Gas and Electric Rates 1261
Cbst of Operatins Electrically Heated Utensils (Table) 1261
Duly Electric Cooking Record for One Week (Table) 1262
Electric Irons for Domestic and Industrial Purposes 1263
Onunercial Electric Laundry Equipment 1263
Eleetric Heating 1263
Radiators and Convecters 1268
Energy Cbnsumption of Electric Heaters 1265
Gamparison between Electric and Coal Heating 1265
Beetrie Car Heating 1265
Industrial Electric Heating 1269
Beetrie Heat in Printing Shops 1269
Soldering and Branding Irons 1270
llttviog Water Pipes 1271
Electric Welding and Forging 1271
Electric Rail Welding 1273
Eaeetrie Smelting 1274
AaneaHng of Armor Plate 1274
Hydro-Electrothermio Ssrstema 1274
PoKDate 1275
T«ted Fuse Wire (Table) 1275
Installation of Fuses 1276
LIGHTNING CONDUCTORS.
Selection and Installation of Rods 1278
Chimney Protection 1281
Teitfl of Lightning Rods 1282
Directions for Personal Safety During Thunder Storms 1283
Economy of Isolated Electric Plants (Tables) 1283
Dtta on Isolated Plants (Table) 1285
Data on Isolated Planttf in Residences (Table) 1287
\
XXXll TABLE OP CONTENTS.
MECHANICAL SECTION.
FOUNDATIONS AND STRUCTURAL MATERIALS.
Page
F6wer Station Construction (Chart) 1289
Foundations 1290
Mortan 1293
Sand and Cement 1294
Weight of Flat Rolled Iron (Table) 1295
Weights of Square and Round Ban of Wrouisht Iron (Table) . . . 1297
Weight of Plate Iron (Table) 1298
U. S. Standard Gauge for Sheet and Plate Iron and Steel 1299
Columns, Pillars and Struts 1800
Strength of Materials laoi
Moment of Inertia 1802
Radius of Gyration 1808
Elements of Usual Sections (Table) 1303
Cast-Iron Columns 1806
Transverse Strength 1808
Fundamental FormuUe for Flexure of Beams 1808
General Formulie for Transverse Strength of Beams (Table) .... 1809
Approximate Greatest Safe Load on Steel Beams (Table) 1810
Beams of Uniform Strength Throughout Their Length 1312
Trenton Beams and Channels (Tables) 1318
Size and Distance between Floor Beams (Table) 1815
Properties of Timber (Table) 1816
Tests of American Woods (Table) 1317
Wooden Beams (Table) 1318
Southern Pine Data (Tables) 1320
Masonry 1322
Brick Work (Tables) 1321
Weight of Round Bolt Copper (Table) 1323
Weight of Sheet and Bar Brass (Table) 1328
Composition of Rolled Brass (Table) 1323
Weight of Copper and Brass Wire and Plates (Table) 1324
Galvanised Iron Wire Rope (Table) 1325
Transmission or Haulage Rope (Table) 1325
Iron and Steel Hoisting Rope (Table) 1320
STEAM.
Steam Boilers 1327
Types of Boilers 1327
Horee Power of Boilers 1327
Heating Surface of Boilera 1328
Grate Surface of Boilers 1329
Efficiency of Boilers 1329
Strength of Boiler Shells (Table) 1330
Rules Governing Boiler Inspection 1332
••<
TABLE OP CONTENTS. XXXUl
Page
Boiler Stays and Bnuses 1338
Boiler SeiUnsB 1334
CbimMya (Tables) 1338
dumney Constructioii 1339
BloweiB for Foroed Draft 1344
Pim for Induced Draft 1345
Eiadi and Ingredients of Fiieb 1346
ToUl Heat of GombuBtaon of Fuels 1347
Temperature of fire (Table) 1340
Amencan Woods (Table) 1340
American Coals (Table) 1360
Heating Value of Goah 13M
Anthracite Coal (Table) 1351
fiitominous Goal (Table) 1351
Approximate Analysis of Goal (Table) 1352
Anlyais of Coke 1353
Siiaee Required to Stow a Ton of Coal (Table) 1353
Wttght of Coal (Table) 1354
Rcbtive Values of Coals and How to Burn Them 1355
Wood as Fuel 1356
liquid PuelB 1356
Chemical Composition of Petroleum Oils 1357
Cbmparative Costs of Oil and Coal (Table) 1358
Mechanical Stoking 1350
Water 1360
Weight of Water (Table) 1361
Water for Boiler Feed 1362
flbhibilities of Scale-making Materials 1363
Purification of Feed Water by Boiling 1365
Table of Water AnalysM 1366
Feed Pumps 1367
Pomping Hot Water 1367
Injectors 1370
Ddiverics for Live Steam Injectors (Table) 1871
Rste of Flow of Water Through Pipes (Tables) 1373
Lose of Head Due to Bends 1374
Feed Water Heaters 1375
SsYinc by HeaUng Feed Water 1376
Pomp Exhaust 1377
Fuel EooDomisen 1378
Steam Separators 1380
SifetyValva 1382
Rules for Conducting Boiler Teste 1384
Determination of Moisture in Steam 1394
Tlirottling Glalorimeter 1304
Ikistuie in Steam (Table) 1396
Separating Odorimeter 1308
Qoslity of Steam Shown by Issuing Jet 1400
Fsctors for Evaporation (Table) 1400
XXXIV TABLE OP CONTENTS.
Properties of Saturated Steam (Table) 1404
Superheated Steam 1413
CoDdeusation in Steam Pipes 1415
Overflow of Steam from Initial to Lower PranureB (Table) .... 1416
Steam Pipes 1417
Flow of Steam Through Pipes (Table) 1417
Equation of Steam Pipes (Tables) 1413
Protection of Steam-Heated Surfaces (Table) 1421
Relative Value of Steam Pipe Ooverin^i 1422
Relative Ek»nomy of Different Thicknesses of Covering 1424
Wrought-Iron Welded Steam Gas and Water Pipe (Table) .... 1427
Lap- Welded Charcoal- Iron Boiler Tubes (Table) 1428
Collapsing Pressure 1429
Resistance of Tubes to Collapse 1420
Table of Dimensions. High-Pressure Cast-iron Screw Flanges (Table) 1430
Tensile Strain of Bolts (Table) 1431
Pipe Bends 1431
Standard Pipe Flanges (Table) 1433
Steam Engines 1434
Digest of Report on Standardization of Engines and Dynamos . . . 1435
Standardised Dimensions of Direct-Connected Generating Sets (Table) 1438
Summary of Tests of Steam Engines (Table) 1439
Horse Power of Steam Engines 1440
Cylinder Ratios in Compound Engines 1441
Number of Expansions for CJondensing Engines 1441
Mean Effective Pressure per Pound Initial Pressure (Table) .... 1442
Condensers and Pumps 1443
Ejector Condenser Capacities (Table) 1445
Air Pumps 1446
(Srculating Pumps 1446
Cooling Tower Test 1447
Gas Engines 1448
Classification 1448
Comparative Economy 1449
Value of Coal Gas of Different Camlle Powers for Motive Power
(Table) 1450
(3as Engine Power Plant 1450
Gs8 Engine Pumping Plant 1451
Steam Turbines 1451
De Laval Steam Turbine 1452
Pareons Steam Turbine 1453
Curtis Steam Turbine 1455
Steam Table 1458
ft
WATER POWER.
Synopsis of Report Required on Watcr-Powcr Property 1460
MiU Power 1462
Comparison of Columns of Water (Table) 1463
Yearly Expense per H.P. on Wheel Shaft (Table) 1464
TABLE OF CONTENTS. XXXV
Page
PMBore of Water (Table) 1465
Biv«tod Steel Pipes 1466
Data for FlumeB and Ditches . . . 1468
Wooden Stave Pipe 1468
Rireted Hydraulic Pipe (Table) 1469
Theoretical Velocity and Discharse of Water (Tubles) 1470
Flow of Water through an Orifice - 1471
Measurement of Flow of Water in a Stream 1471
Theory of Rod Float Gauging 1471
ICnera' Inch Measurements 1473
flow of Water over Weirs 1478
Weir Table 1474
CUcttlating the Hoxse Power of Water (Table) 1475
Water Wheels 1476
TWjiiMB 1476
Impobe Water Wheel 1480
SHAPTIlfG, PULLEYS, BELTING. ROPE-DRIVIKG.
Shafting 1481
Deaeetion of Shafting 1482
Hone Power Transmitted by Shafting 1483
Hone Power Transmitted by Cold-Rolled Iron Shafting 1484
Hollow Shafts 1485
Table for Lasring out Shafting 1486
PoDeys 1487
BdUng 1487
Width of Belt for Different Horse Power 1488
Hone Power Transmitted by Different Belts (Tables) 1489
Rope Driving 1490
Hone Power of Manila Rope (Table) 1491
Table of Horse Power of Transmission Rope 1493
Slip of Ropes and Belts 1493
Stiaiia Produced by Loads on Inclined Planes (Table) 1494
TVaosmission of Power by Wire Ropes (Table) 1495
(Jain (Tables) 1496
Labrication 1497
hinting 1498
MISCELLAlfEOUS TABLES.
Weights and Measures. English and Metric (Tables) 1499
Greek Letters 1605
Aagnlar Velocity 1505
Friction 1505
Temperature or Intensity of Heat 1506
Oomparison of Different Thermometers (Table) 1506
Coefficients of Expansion of Solids (Table) 1508
Specific Heats of Metals (Table) 1509
Heat Unit Table 1510
(
/
xxxvi ta6le of contents.
Specific Heat of Gases and Vapors (Table) 161
Total Heat of Steam 151
Mechanical Equivalent of Heat 1511
Specific Gravity (Table) 1519
POWER REQUIRSD TO DRIVE MACHIlfBRT, SHOPS AKD TO DO
VARIOUS KIHD6 OF WORK.
Prony Brake 1515
Horse Power Formulas 1515
Power Used by Machine Tools (Table) 1515
Motor Power for Machine Tools (Tables) 1518
Horse Power in Machine Shops, Friction, Men Employed (Table) 1523
Cotton Machinery (Table) 1524
Power Required for Printing Machinery (Table) 1525
Power Required for Sewing Machines 1525
Power Consumption in Industrial Blstablishments (Table) 1528
Power for Electric Cranes 1627
Operating Cost of Electric Elevators 1628
Saving by Electric Drive 1529
List of Tools and Supplies Used for Installing Electric Lis^ts and
Dynamos 1530
Material Required for installing Lamps 1531
Thawing Frosen Water Pipes Electrically 1531
INDEX 1633
SYMBOLS. UNITS, INSTRUMENTS.
CHAPTER I.
«
The followin£ Itet of symbols has been compiled from various sources as
beUur those most commonly in use in the United States. Little variation
wiUbe found from similar lists already publishtnl except the elimination of
wme that may be considered exclusively foreign. The list has been revised
by competent authorities and may be considered as representing the best
Bssffe^
I, Length, cm. =r centimeter ;
in., or ''=inch, ft. or ' =
foot.
Jf, Mass. gr. = mass of 1
gramme ; kg. = 1 kilo-
gramme.
T,tj Time. 5= second.
]>erlT«d: geometric.
S, f, Surface,
r, Volume,
t, p. Angle. »
Mechanical.
V, Velocity,
n. Momentum.
«, Angular velocity,
a, Acceleration.
9, Acceleration due to gravity
=32.2 feet per second.
F, /, Force,
r, Work.
P, Power.
<, Dyne, 10 3 = 10 dynes.
ft. lb.,
H.p. , h.
I.H.P.,
B.H.P.,
E.n.F.i
k
«.
^
Foot-pound,
.p. : HP, Horse-power.
Indicated horse-power.
Brake horse-power.
Electrical horse-power.
Joules' equivalent.
PresBQre.
Moment of inertia.
Quantity.
Current.
Potential Difference.
Resistance.
Capacity.
Specific Inductive capacity.
Derived lHakC*«tic.
Strength of pole.
Magnetic moment.
Intensity of magnetisation.
3.
Intensity of magnetixation.
Horixontal intensity of
«^rth*s magnetism.
Field intensity.
f lagnetio Flux.
r^agnetic flux density or
magnetic induction.
Magnetizing force.
Magnetomotive force.
Reluctance, Magnetic re-
sistance.
Magnetic permeability.
Magnetic susceptibility.
Reluctivity (specific mag-
netic resistance).
JD«ri%'«d f lectromarttetlc.
Resistance, Ohm.
do, megohm.
Electromotive force, volt.
Difference of potential, volt.
Intensity of current, Ampere.
Quantity of electricity. Am-
pere-hour; Coulomb.
Capacity. Farad.
Electric Energy, Watt-hour ;
Joule.
Electric Power, Watt ; Kilo-
watt.
Resistivity (specific resis-
tance), Ohm-centimeter.
Conductance, Mho.
Conductivity (specific con-
ductivity.
Admittance, mho.
Impedance, ohm.
Reactance, ohm.
Susoeptance, mho.
Inductance (coefficient of
Induction), Henry.
Ratio of electro-magnetic to
electrostatic unit of quan-
tity = 3 X 10*® centimeters
per second approximately.
0jmbola 1m ir«»«'<^l ume,
D, Diameter.
Radiiis.
Temperature.
Deflection of gahranometer
needle.
n.
A
c.
r,
t.
SYMBOLS, UNU'S, INSTRUMENTS.
A^.n.
I'
A.M.
V.M.
A.C.
D.C.
P.D.
C.G.S.
B. AS.
Number of ftnything.
Circamfereuce — cQameter :
8.141fi82.
2irN = 6.2831 X frequency, ID
alternating current.
Frequency, periodicity) cy-
cles per second.
Galvanometer.
Shunt.
North pole of a magnet.
South pole of a magnet.
Ammeter.
Voltmeter.
Alternating current.
Direct current.
Potential dilference.
Centimeter, Qramme, Second
system.
Brown & Sharpe wire gauge.
K.p.m.,
U.Pi
B.W.G., Birmingham Wire gauge.
UttJuJ
TncJnnr>
Revolutions per mixinte.
Oandlepower.
Incandescent lamp.
Arc lamp.
Condenser.
Battery of cells.
Dynamo or motor, d.c.
Dynamo or motor, a.o.
Converter.
Static transformer.
Inductive resistance.
Non-iudufitive resistance.
CHAPTER U.
Mjidex. ]f otAtloB.
Electrical units and values oftentimes require the use of large numbers
of many figures both as whole numbers and in decimals. In order to avoid
this to a great extent the index method of notation is in universal use in
connection with all electrical computations.
In indlcatinga larffenumber. for example, gay, a million, instead of writ-
ing 1,000,000, ft would by the index method bo written 10" ; and 3S.00O QOQ
would be written 36 X 10». '
A decimal is written with a minus sign before the exponent, or, tA« = .01
= tO-« ; and .00048 is written 48 x 10-». t^ . . t«b
The velocity of light is 80,000,000,000 cms. per sec., and is written 3 x 10".
In multiplying numbers expressed in this notation the significant figures
are multiplied, and to their product is annexed 10, with an index equal to
the sum of the Indices of the two numbers.
In dividing, the significant flgnrcs are divided, and 10, with an index equal
to the a»#«rence of the two indices of the numbers is annexed to the divi-
dend.
Fundant^atal Cntta.
The physical qualities, such as force, velocity, momentum, etc., are ex-
pressecl In terms of lenf/th^ mcuts^ time, and for electricity the system of
terms in universal use is that known as the C. G. S. system,
viz. : The unit of length is the Centimeter.
The unit of mass is the Qramme.
The unit of time is the Second.
Expressed in more familiar units, the Centim^^ is equal to .3937 inch in
lengtn ; the Qramme is equal to 15.432 grains, and represents the mans or
quantity of a cubic centimeter of water at 4° C, or 39.2° Fah. ; the Secotirl is
the HsiJkrov I^'^ o' ^ sidereal day, or the «b}bo part of a mean solar day.
These units are also often called absolute units.
Oerlved Oeomefric tJnlta.
The unit of area or surface is the square centimeter.
The unit of volume is the cubic centimeter.
Oarived Iflecliantcal ITnltn.
Velocity is the rate of change of position, and is uniform velocity when
equal distances are passed over In equal spaces of time ; unit velocity Is a
rate of change of one centimeter per second.
ELECTRICAL EKGINEEKING UKITS.
An/gniat Feleeiip is the angular distance about a center passed through in
«K Mcond of time. Unit ansruiar velocity is the yelooity oX a body moving
jseirenlar path, whose ramus is unity, and which would traverse a unit
.Mgle is unit time. Unit angle is 57°, 17^ 44.8^' approximately ; i.e., an angle
rnim are equals its radius.
iMtmatum is the quantity of motion in a body, and equals the mat$ times
P0 vthcitjf,
JeeeUraiUm Is the rate at which velocity changes ; the unit is an aceel*
tion of one centimeter per second per second. The acceleration due to
iTity is the increment in velocity imparted to falling bodies by gravity,
' a OBOsiiy taken as 32.2 feet per second, or 981 centimeters per second,
▼slue diiiers somewhat at different localities. At the North Pole g=:
1; at the equator g=978.1 ; and at Greenwich it is 981.1.
Force acts to eliange a body's eondition of rest or motion. It is that which
mds to produce, alter, or destroy motion, and is measured by the time rate
f cliange of momentum produced.
Tbe oait of force is that force which, acting for one second on a mass of
le ^nunme, gives the mass a velocity of one centimeter per second ; this
lit IS eallec^a dyne. The force of sravity or weight of a mass in dynes may
) fooad by multiplying the mass m grammes by the value of ^ at the pai^
eolarplace where the force is exerted. The pull of gravity on one pound
ibe United States may be taken as 446»000 dynes.
V9rk is the product of a force into the distance through which it acts,
unit is the erg^ and equals the work done in pushing a mass through a
aee of one centimeter sgainst a force of one dyne. As the " weight"
oaegnmmB is 1 x 981, or 961 dynes, the work done in raising a weight of
e gramme through a height of one centimeter against the force of gravity,
M dynes, equals 1 X 981=981 ergs.
na kilogramme- meter 7=: 100000 x 981 ergs.
'mac energy is the work a body is able to do by reason of its motion.
^(AmtitU energy is the work a body is able to do by reason of its position.
3to onit of energy is the erg,
*ovtr is the rate of workiiig, and the unit is the wattz=. IdC ergs per sec.
jte-ptmer is the unit of power in common use and, although a somewhat
ifrary unit, it is difficult to compel people to change from it to any other.
equate 33,000 lbs. raised one foot high in one minute, or S50 foot-pounds
^leoond-
ft.4b.= 1.356 X lO' ^rgs.
Tatt= 10* ergs per second..
fcoree-power=6BO x 1.356 X 10* ergs = 746 watts. If a current of I am-
EI I*R
Sow through B ohms under a pressure of E volts, then =— = -=2^ =
^represents the horse-power involved.
b French *■*■ force de chevcU" =736 watts =542.48 ft. lbs. per 8ec.=
H. P^ and 1 H.P. = 1.01389 '* force de chev<U:*
The Joule ^^1/= 10' ergs, and is the work done, or heat generated, by
tt ssoond, or ampere flowing for a second through a resistance of an ohm.
ff=heat generated in gramme calories,
/= current in amperes,
£=e.mX in volts,
J?=: resistance in ohms, and
/= time In seconds,
'J?=0u24/*iZt=0.24 Elt. gramme calorie* or therms.
IEt=zniU=:~=:EQ=zJoule».
\l horBe-iK>ver=650 foot-pomids of work per second,
Joules =:^^BQ=: .7373 EQ ft. lbs.
Heat Vmlte.
BHHah Thermal Unit is the amount of heat required to raise the
itore of one poimd of water one deg. F. at or near its temp, of max.
.. 30.1**; = 1 pound-degree-Fah. = 251 .0 French calories.
I Calorie is the amount of heat required to raise the temperature of a
i
4 SYMBOLS, UNITS, INSTRUMENTS.
nuiflB of 1 gramme of water from 4° C. to 5*^ C. = 1 gramme-degree-oei
grade.
Water at 4° G. ia at its maximum density.
Joules eqtUfXilent^ J, is the amount of energy equal to a heat unit.
For a B.T.U., or puund-degree-Fah., J=zl.(37 x 10** ergs., or = 778 f<
pounds.
For one pound-degree — Centigrade, J=: 1.93 x 10>" ergs.
For a ceiiorie /= 4.189 x 10^ ergs.
The heat generated in t seconds of time is
—J- = -J- , where .f =4.189 x 10',
and /, Rt and E are expressed in practical miits.
Blectrlcttl IJBita.
There are two sets of electrical units derived from the fondamea
C. Q. S. units ; yis., the electrottatic and the electromagnetic. The fin
iMuied on the force exerted between two quantities of electricity, and the t
ond upon the force exerted between a current and a magnetic pole. 0
ratio of the electrostatic to the electromagnetic units has been carefully
termined by a number of authorities, and is found to be some multiple
sub-multiple of a quantity represented by &, whose value is approximat
3 X 10^* centimeters per second. Convenient rules for changing from one
the other set of units will be stated later on in this chapter.
Eleccroatiatic VmIU.
As yet there have been no names assigned to these. Their values are
follows :
The unit of quantity is that quantity of electricity which repels witi
force of one dyne a similar and equal quantity of electricity placed at v
distance (one centimeter) in air.
Unit of current is that which conveys a unit of quantity along a cond
tor in unit time (one second).
C/nit difference of potential or unit electro-motive force exists between t
points when one erg of work is required to pass a unit quantity of elootrie
from one point to the other.
Unit of reeittance is possessed by that conductor through which unit e
rent will pass under unit electro-motive force at its ends.
Unit of capacity is that which, when charged bv unit potential, will h*
one unit of electricity ; or that capacity which, when charged with one v
of electricity, has a unit diiference of potential.
Specific inductive capacity of a substance is the ratio between the ca]
of a condenser having that substance as a dielectric to the capacity oj
same condenser using dry air at 0° C. and a pressure of 76 centimet
the dielectric.
Marn^ttc' (Jntta.
Unit Strength of Pole (symbol m) is that which repels another simili
equal pole with unit force (one dyne) when placed at unit distance
centimeter) from it.
Magnetic Moment (svmbol ^)1t ) if> the product of the strength of
pole into the distance between the two poles.
Intensity of Magnetization is the magnetic moment of a magnet dii
by its volume, (symbol (J)«
Intensity of Magnetic Field (symbol JC ) ^s measured by the force it l
upon a unit magnetic pole, and therefore the unit Is that intensity ol
wnich acts on a unit pole with a unit force (one dyne).
Magnetic Induction (symbol (B) is the magnetic flux or the nnml
magnetic lines per unit area of cross-section of magnetized materii
area being at every point perpendicular to the direction of flux. It
to the magnetixing force or field Intensity JC niultiplied by thept
f&: the nnu is the gauss.
Magnetic Flux (symbol «) is equal to the average field intensity mall
by the area, its unit is the maxwell.
MagnetUdng Force (symbol JQ, ) per unit of length of a solenoid
BLECTBICAL SNOIXEERIXG UNITS.
irlfl-i-L where N':=z the number of turns of wire on the solenoid : X =
dw loigth of the solenoid in cms., ttnd / = the current in absolute units.
MagneiamoHve Force (symbol fp ) is the total niagnetizlng force deyeloped
ta a magnetio oircvit by a coil, equals 4 r i^/, and the unit is the gil-
heri.
MdmUamfce, or Magnetic ReHstance (symbol (J^, is the resistance offered to
tibe macnetle flax by the material magnetizeOf and is the ratio of magneto-
Botireiorce to magnetic flux; that is, unit magnetomotive force will generate
a unit of magnetic flux through unit reluctance : the unit is the oersted; i.e.,
the reluctance offered by a cubic centimeter of vacuum.
Miaguetic J^ermeability (symbol fi) is the ratio of the magnetic indnotion
^ to the magnetizing force JCt that is ^ = m>
Magmetie Su8cq[ftibiUtg (symbol «) is the ratio of the Intensity of mag-
n to the magnetizing force, or k = ;^ •
Bdmetivit^, or SpecUic Magnetic Reeistance (symbol v), is the reluctance
nait of_ length and of unit croes-seotton that a material offers to being
SlectroBiagvettc ITnlta.
RtHetanee (srmbol R) is that property of a material that opposes the flow
«f aeurrent or electricity through it; and the unit is that resistance which,
vifli an electro-motive force or pressure between its ends of one unit, will
fermit the flow of a unit of current.
nw practical unit is the oAm, and its value in C.S.O. units is 10*. The
Litedard nnit is a column of pure mercury at 0^ C, of uniform cross-section,
IMZ centimeters long, and 14.4521 grammes weight. For convenience in use
I irverv high resistances the prefix meg is used; and the megokmy or million
MBS, becomee the unit for use in expressing the insulation resistances of
[sshmarine cables and all other high resistances.
L MAeetro-moHve Force (symbol E) is the electric pressure which forces, the
HBratt through a resistance, and unit £.M.F. is that pressure which will
^hnt a nnit c^irrent one ampere through a unit resistance. The unit is the
nltfSiHi the practical standard adopted by the international congress of elec-
Menas at CLicago in 1893 is the Clark cell, directions for making which
-01 be given farmer on. The E.M.F. of a Clark cell is 1.434 volt at 150 C.
The value of the volt in C.G.S. units is 10*. For small £ Ji.F's. the unit
UHtoU, or one-thousandth volt, is used.
lbs International Volt is 1.1358 B. A. volts; and the ratio of B. A. volt
die International volt is .9866.
difcremce of Potential^ as the name indicates, is simply a difference of
aetric preeeore between two points. The unit is the volt,
Oerrent (symbol /) Is the intensity of the electric current that flows
hough a clroait. A unit current will flow through a resistance of one
;<kaL, with an tfectro-motive force of one volt between its ends. The unit
tkeampere, and is practically represented by the current that will eleotro-
Sa^Kwit silver at the rate of .001118 gramme per second. Its value
. units is 10 ~*. For small values the milliampere is used, and it
■Is one-thousandth of an ampere.
n« QwanHiv of Electricity (symbol 0 which passes through a given cross-
Ktion of an individua] circuit in t seconds when a current of /amperes is
Sis eqnal to Jt units. The unit is therefore the ampere-second. Its
the Coulomb, and its value in C.G.S. units is 10-*.
Cetpacity (symbol C) is the property of a material condenser for holding
dMrae of electricity. A condenser of nnit capacity is one which will be
wed to a potential of one volt by a <mantity of 1 coulomb. The unit is
wad^ ita C.Q.S. value is 10-* ; and tnis being so much larger than ever
ilna in practical work, its millionth part, or the micro-farad^ is used as
practieal unit, and its value in absolute units is 10 ~ i^. A condenser of
4hird micro-farad capacity is the size in most common use in the U. S.
Ifattoic Energy (symbol W) is represented by the work done in a circuit
eondnetor by a current flowing through it. The unit is theJotUe, its
lute ralne la 10'' ergs, and it reprepresents the work done by the flow
He second of unit current (1 ampere) through 1 ohm.
EUetrie Power (symbol F^ is measured in watte^ and Is represented by a
of 1 ampere under a pressure of 1 volt, or 1 Joule per second. "Die
BTHBOLS, UNITS, HEASUBEHENT3.
hfiil
ll
C 1
lit
111
jp
• Is
If
II il II II nil II
- t. . » &.fc ft.
JM
II 4
1
lis
111
m
in
liss
sill
Iffl
Is si
lis
EI^tiTRICAL ENOINEKRING UNITS.
.1!
Ill
Hi il
« I » 3 4
II
I -I ^
11
is
Nitfljlil
' 5 ? : 1 1 3 1 1 i-
8
SYMBOLS, UNITS, INSTRUMENTS.
I
■
a
e
Z
n
I
9
■
or
£
4!
1
a
£22s3
88 W
S
a
1
Sao
6
5^(
© 2.
£•5
03
•i
•3
o
I
1.
s
V
E
.£4
O
o
.d
6
5 13 5
o
i^si
9
O
5
^-"2 a
o
9
0)
B
•S 2
fib ••*
® ■♦»
•3 *
1^
I
8 S S
Xi
.a
2
»
ff
s.
O ^ M
9
s
s
o
V
6
I
o
a
a
9
9 .
.a
08
§ S o
•S "S 'S
u^ I S I
I
III
*«• HN ^
i, ?1 t f^
^ ^ 2i 2,
2j "^ "^ t^ s "^ ""J
e^
II II II II ]i II II II II . II > E >
fcjSoO^ft, o.;*, ?.s .ts II]] II
N ^ 03
C5
I
►-* •^' <-:: f" ^ *• * «r ^
• « ^ N ^ fl^
s
9
00
s
0
O
0
c
as 00 ^_
O . 9 *iO ° 9
I
Pi
3
9
OQ
INTSBNATIONAL BLECTBICAL UNITS. 9
watt eoTuds 10' absolute unite, and 746 watte OQnals 1 hone-power. In elec-
trie Seating and power the unit kilowatt, or 1000 watte, is oonslderably used
to M,rwd the use of large numbers.
JSoMfinfir (symbol o) is the speclfle reelstanoe of a substance, and is the
raslstence in ohms of a centimeter cube of the material to a flow of our-
rsnt between opposite faces.
Qmduetance (symbol G) is that property of a metal or substance bv which
ft eondncte an electric current, and equals the reciprocal of ite resistanoe.
The unit proposed for conductance is the MhOt but It has not come into
prombient use as yet.
Qmdnclivitp (symbol v) is the specific conductance of a material, and is
therefore the reciprocal of ite resLBtiTitT. It is often expressed in compari-
•on with the conductivity of some standard metal such as silyer or copper,
and is then stated as a percentage.
Imduetance (symbol £), or coefficient of self-induction, of a circuit is that
coefficient by which the time rate of chan^ of the current in the circuit
most be multiplied in order to give the E.M.F. of self-induction in the
dreait. The practical unit is the Httnry^ which equals 10^ absolute units,
and eziste in a circuit when a current varying 1 ampere per second produces
%wolt of electro-motive force in that circuit. As the henry is so large as to
be seldom met with in practice, 1 thousandth of it, or the miUi-henry, is the
SBit most In use.
Below will be found a few rules for reducing values stated in electrostatie
■nits to unite in the electro-magnetic system. To reduce
eleotrostatic potenHeU to volt$, multiply by 800 ;
** capacity to micro-faradM^ divide by 900,000 ;
** quantity to eouUmbw, divide by 3 x 10* ;
^ current to cunperes^ divide by 3 x 10*;
" rtMittanee to okm$, multiply oy 9 X 10^^.
nmMlf ATlOIf AI. SIiECTRICAI. IJlflTA.
At the International CJongress of Eleotrioians, held at (Thicago, August 21,
Un, the following resolutions met with unanimous approval, and being
approved for publication by the Treasury Department ox the United States
wrremroent, Deo. 27, 1893, and legalised by act of Congress and approved
hj the President, July 12, 1894, are now recognised as the International
imite of value for their respective purposes.
RESOL VED, That the several govemmento represented by the delegates
of the International (Congress of Electricians be, and they are hereby,
recommended to formally adopt as legal unite of electrical measure the
following:
1. As a unit of reaistanee, the International ohm^ which Is based upon the
ohm equal to 10* unite of resistanoe of the C.O.S. system of electro-magnetic
ttoJte, and Is represented by the resistance offered to an unvarying electric
current \^ a column of mercury at a temperature of melting ice, 14.4521
grammes In mass, of a constant cross-sectional area, and of the length 106.3
ccDtimeters.
2. As a unit of current^ the International ampere, which is one-tenth of the
imit of current of the C.G.S. system of electro-magnetic unite, and which is
represented sufficiently well for practical use by the unvarying current
which, when passed through a solution of nitrate of silver in water, in
seeordance with the accompanying specification (A) deposits silver at the
rate of 0.001118 gramme per second.
3. As a unit of electro^motive force the international volt which is the
E.M.F. that, steadily applied to a conductor whose resistance is one Inter-
national ohm, will produce a current of one international ampere, and
which is represented suffleiently well for.praotical use by ^^04 of the X:.M.F.
between the poles or electrodes of the voltaic cell known as Clark's cell at
a temperature of 15^ G, and prepared in the manner described in the ac-
companying specification (B).
4. As the unit of quantity ^ the International coulombt which is the quan-
tity of electricity transferred by a current of one international ampere in
one second.
5. As the unit of capacity the international farads which is the capacity
(
1
10 SYMBOLS^ UNITS, INSTBUMBNT8.
of a oonductor charsod to AvotenHal of one tntemoHonal voU by one inter-
national coulomb of electricity.
6. As the unit of workf the Joule, which is 10^ unite of work in the C.O.S.
system, and which is represented sufAdently well for practical use by the
energy expended in one second by an international ampere in an inter-
national ohm.
7. As the unit ot power, the waM, which is equal to 10 ^ units of power in the
C.G.S. system, and^whicii is represented sufnoiently well for practical use
by the work done at the rate of one Joule per second.
8. As the unit of induction^ the henryf which is the induction in the cir-
cuit when the E.M.F. induced in this circuit is one international Tolt, while
the inducing current raries at the rate of one international ampere per
second.
•peciflcatloM A.
In employing the silver yoltameter to measure currents of about one
ampere, the following arrangements shall be adopted :
The kathode on wmoh the silrer is to be deposited shall take the form of
a platinum bowl not less than 10 cms. in diameter, and from 4 to 5 cms. in
depth.
The anode shall be a disk or plate of pure silver some 30 sq. ems. in area,
and 2 or 3 cms. in thickness.
This shall be supported horizontally in the liquid near the top of tho
solution by a silver rod riveted through its center.
To prevent the disintegrated silver which is formed on the anode firom
falling upon the kathode, the anode shall be wrapped around with pure
Alter paper, secured at the back by suitable folding.
The liquid shall consist of a neutral solution of pure silver nitrate, con-
taining aoout 15 parts by weight of the nitrate to 86 parts of water.
The resistance of the voltameter changes somewhat as the ourrent passes.
To prevent these changes having too great an effect on the current, some
resistance, besides that of the voltameter, should be inserted in the circuit.
The total metallic resistance of the circuit should not be less than 10 ohms.
Method •r maklMg- a ]Wetta«v«HseMt. — The platinum bowl is to
be washed consecutively with nitric acid, distilled water, and absolute
alcohol ; it is then to be dried at 160^ C, and left to oool in a desiccator.
When cold it is to be weighed carefully.
It is to be nearly filled with the solution, and conne<ited to the rest of the
circuit by being placed on a clean copper support to which a binding-screw
is attached.
The anode is then to be immersed in the solution so as to be well covered
bv it, and supported in that position ; the connections to the rest of the
oirouit are then to be made.
Contact is to be made at the key. noting the time. The ourrent is to be
allowed to pass for not less than half an hour, and the time of breaking
eontact observed. ^
The solution is now to be removed from the bowl, and the deposit washed
with distilled water, and left to soak for at least six hours. It U then to be
rlused successively with distilled water and absolute alcohol, and dried in a
hot-air bath at a temperature of about 160° C. After cooling In a desiccator
**m ^ ^J?®%^®^ Ag&in. The gain in mass gives the silver deposited.
To find the time average of the current in amperes, this mass, expressed
m grammes, must be divided by the number of seconds durins which thf
ourrent has passed and by 0.001118.
In determining the constant of an instrument bv this method the current
«f«»^fc.^5i as nearly uniform as possible, and the readings of the instru-
ment observed at frequent intervals of time. These observations give a
SSIILr^i^^KT^'®^ ^\^ reading corresponding to the mean current (time
average of the current) can be found.
tW^readln*"* ** calculated from the voltameter resulU, corresponding to
The current used in this experiment must be obtained from a battery and
not from a dynamo, especially when the instrument to be calibrated Is an
electrodynamometer.
ftpecMlca«l«B B. — The Volt.
The cell has for its positive electrode, mereory, and for Its negative elec-
trode, amalgamated sine : the electrolyte oonslsts of a saturateosolution of
BPEOIFIOATtaH ft
11
tfMtqhluto and merenrooa sulphate. The eleotromoilTe tone Is 1^484 Tolts
at 15° CC, and, between 1(P C. and 25o C, by the increase of !• C. in tempera-
mre, tlie eleetromotlTe foree decreases by .00115 of a volt.
1. BrmpmnMmm ef the Mercmvy. — To secure purity it should be
Int treated with acid in the usual manner, and subsequently distilled in
TaCQO.
S. PreparstloM ef the Zl»c Amalcan.— The sine designated in
eoDunerce as ** commercially pure** can be used without further prepara-
tton. For the preparation of the amalgam one part bv weight of sine Is to
be added to nine (9) parts by weight of mercury, and ooth are to be heated
ta a porcelain disli at 100^ 0. with moderate stirring until the zinc has been
fully diwolved in the mercury.
3. Prvpanatieia of tlie MeswHooe A«Ipluate. — Take mercurous
folDlute, purchased as pure, mix with it a small quantity of pure mercury,
aad vash the whole thoroughly with cold distilled water by agitation in a
bottle ; drain oif the water and repeat the process at least twice. After the
laitTashine, drain off as much of the water as possible. (For further de-
tails of ponilcation, see Note A.)
4. PrapanatloB of the Ziac Solpluato Aolvtloa.— Prepare a
aeotral aatorated solution of pure re-crystallised sine sulphate, free from
inn. by mixing distilled water with nearly twice its weight of crystals of
pare zinc sulphate and adding zinc oxide in the proportfon of about 2 per
ent b? weight of the zinc sulphate crystals to neutralize any free acid, ^e
aymk should be dissolved by the aid of gentle heat, but the temperature
to Thieb the solution is raised must not exceed 90^ C. Mercurous sulphate,
treated as described in 3. shall be added in the proportion of about 12 per
ecu by weight of the zinc sulphate crystals to neutralize the free zinc oxide
laaaini]^, and then the solution filtered, while still warm, into a stock
bottle. Crystals should form as it cools.
i. PiepsitwtloB of the Meiwrova Sislpliato aiad Zioc ftial-
pkale JPaete. — for making the paste, two or three parts by weight of
Bereoroos sulphate are to be added to one by weight of mercury. If the
fidphate be dry, it is to be mixed with a paste consisting of zinc sulphate
o^Mb and a concentrated zinc sulphate solution, so that the whole con-
*aaXtt a Btiif maas, which is permeated throughout by zinc sulphate crys-
t>lt and globules of mercury.
If the sulphate, however, be moist, only zinc sulphate crystals are to be
>dded ; care must, however, he taken that these occur in excess, and are
Mtdlisolved after continued standing. The mercury must, in this case
•bo, permeate the paste in little globules. It is advantageous to crush the
ifaK f olphate crystals before using, since the paste can then be better
Baaipalated.
le se« op tho Coll. —The conUining glass vessel, represented in the
lenopanying llgnre, shall consist of two limbs closed at bottom, and Joinea
•bore to a common neck fitted with a ffround-glass
^^liper. The diameter of the limbs should be at
n«t 2 ems. and their length at least 3 cms. The
>eek should be not less than 13 cms. in diameter.
it the bottom of each limb a platinum wire of
^t 0.4 mm. in diameter is sealed through the
To set up the cell, place In one limb mercurv,
*si in the other hot liquid amalgam, containing 90
^vta mercury and 10 partu zinc. The platinum
vvea at the bottom must be completely covered
b^the mercury and the amalgam respectively. On
fte mercury, place a layer one cm. thick of the
^ and mercurous snlphate paste described in 5.
»th this paste and the zinc amalgam must then
kenvered with a layer of the neutral zinc sul-
1^ crystals one cm. thick . The whole vessel must
■eabe filled with the saturated zinc sulphate solu-
^ and the stopper inserted so that it shall just
^h it, leaving, however, a small bubble to guard
^hml breakage when the temperature rises.
before finally inserting the glass stopper, it is to be brushed round its
^Vper edge with a strong alcoholic solution of shellac, and pressed firmly
* Plaoe. (For details of filling the cell see Note B.)
Fxo 1.
12
SYMBOLS, UNITS, INSTRUMENTS.
i
0
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P IS
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8
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B ::• '°-
S 2 a
t-
N
o
04
&
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w
els
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eo
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00
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•«8
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- I §,
d
n
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ill I ^ '
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e
ilo
&
s ^
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CI
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S^
s
s
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- 2
s g
5 ?
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s i '5. '^
op
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00
04 i-H
i§
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X X
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S ®
9
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9 O
4) «
DSSCBIFTION OF INSTRUMENTS. 13
Mmtmm tm tlM Apeeiflc«tl«Mi«
(J}. ViM Hevcvrovs S«lph»te.—The treatment of the merouroiu
Bolphate bM for its object the remoyal of anv mercuric sulphate which de-
eomposes in the preeenoe of water into an acid and a basic sulphate. The
latter is a yellow substance — turpeth mineral ^ practically insoluble in
vster : its presence^ at any rate In moderate quantities, has no effect on the
cell. If, however, it be formed, the acid sulphate is also formed. This is
lolnble in water, and the acid jproduoed affects the electromotive force. The
oblect of the washings is to dlssolTe and remove this acid sulphate, and for
this purpose the three washings described in the specification will suffice in
lesriy all eases. If, however, much of the turpeth mineral be formed, it
ibows that there is agreat deal of the acid sulphate present ; and it will then
be wiser to obtain a fresh sample of mercurous sulphate, rather than to try
by repeated washinn to get rid of all the acid.
The free mercury helps in the process of removing the acid ; for the acid
■loeuric sulphate attacks it, forming mercurous sulphate.
Pore mercurous sulphate, when quite free from acid, shows on repeated
vMhing a faint yellow tinffo, which is due to the formation of a basic mer-
carooB salt distinct from the turpeth mineral, or basic mercuric sulphate.
Ike sppearanoe of this primrose yellow tinge, which is due to the formation
of a basic mercurous salt distinct from the turpeth mineral, or basic mer-
eurie sulpluute, may be taken as an indication that all the acid has been
rasoved ; the washing may with advanti^e be continued until this tint
Meara.
(B). jnillar tlio Cell. — After thoroughly cleaning and drying the
&B vessel, place It in a hot-water bath. Then pass through the neck of
vessel a tnin glass tube reaching to the bottom to serve for the intro-
dsetion of the amalgam. This tube should be as large as the slass vessel
viU admit. It serves to protect the upper part of the cell irom being
wiled with the amalgam. To fill in the amalgam, a clean dropping-tube
about 10 cms. long, drawn out to a fine point, should be used. Its lower end
k bffoosht under the surface of the amalgam heated in a porcelain dish, and
fome of the amalgam is drawn into the tube by means of the rubber bulb.
Ibe point is then quickly cleaned of dross with filter paper, and is passed
throi^ the vrider tube to the bottom, and emptied by pressing the bulb.
Tb/t point of the tube must be so fine that the amlagam will come out only
oa iqueexing the bulb. This process is repeated until the limb contains the
dadred quantity of the amalgam. The vessel is then removed from the
saier-batlL. After cooling, the amalsam must adhere to the glass, and
most show a clean surface with a metallic luster.
For insertion of the mercury, a dropplng-tube with a long stem will be
loond oonrenient. The paste may be poured in throuah a wide tube reachp-
isf nearly down to the mercury and having a funnel-shaped top. If the
piste does not run down freely it may be poshed down with a small glass
rod. The paste and the amalgam are then both covered with the zinc sul-
•ttate crystals before the concentrated zinc sulphate solution is poured in.
lUs shoald be added through a small funnel, so as to leave the neck of the
Teoel clean and dry.
For oonrenience and security in handling, the cell may be mounted in a
fsitable case so as to be at all times open to inspection.
In using the cell, sudden variations of temperature should, as far as
possible, be avoided, since the changes in electromotive force lag behind
those of temperature.
CHAPTER III.
TOiscRKPnoir oi* nrftTRrMEivTA.
Although no attempt will be made here to f ullv describe all the different
isstmmente used in electrical testing, some of tne more important will be
Bsmed, and the more common uses to which they may be put mentioned.
The four essential instruments for all electrical testing of which all other
faistrumentB are but variations, are: the battery, the galvanometer^ the
Tt$i8taMce4>ox, and the conde^iser, and following will be found a concise
4Meription of the more important types of each.
14
SYMBOLS, UNITS, INSTRUMENTS.
PlUDHAlftir JBAimSlUJBS.
A Voltaic Battery is a device for convertiog chemical energy directly
iato electrical energjr.
If a plate of chemically pure sine and a plate of copper are imm««ed in
dilute sulphuric acid no chemical action takes place. As soon, however,
as the sine and copper plates are connected by an dectrical conductor
outside of the liquid a vworous chemical action is set up. the sine dis-
solves in the add. and hydrogen is liberated on the copper plate. As lon^c
as this action takes place an electric current passes from the sine plat«
through the acid to uie copper plate and through the conductor back to
the sine plate.
The chemical action in this simple voltaic cell soon becomes weaker,
and at the same time the intensity of the electric current diminishes and
finally becomes aero. The diminution of activity is chiefly due to the
accumulation of hydrogen on the copper plate, causing what is known as
"polarization." An agent introduced into a galvanic cell to preveat
polarization is called a "depolarizer."
The chemical reaction of a voltaic cell is directly proportional to the
quantity of electricity passing through it. The quantity (in grammes) of
an element liberated or brought into combination electrolytieaUy by one
coulomb of electridty, is called its electrochemical equivalent. (See table
on second page of section on "Electrochemistry.") The theoretical con-
sumption of material in a voltaic batterv doing a certain amount of work
can be calculated from the electrochemical equivalent of the material. For
example, in a battery doing work equivalent to one horse-power hour
746 X 3600 X .(X)3387
E
grammes of sine will be dissolved: E being the E.M.F. of the battery.
In practice the oonsxmiption of material in a galvanic cell is larger, due
to local action. €k>mmercial zinc always contams iron, carbon, or other
impurities: as soon as these are exposed to the liquid, local dosed circuits
are formed resulting in the consumption of zinc To prevent this wasteful
action, the zinc must be amalganuited with mercury. The action of the
mercury brings the pure zinc to the surface and in contact with the liquid.
Amalgamated zinc is not attacked by diluted sulphuric acid.
Zinc is amalgamated by immersing it in dilute sulphuric or hydrochlorio
acid for a few minutes to give it a clean surface, then mercury is rubbed on
with a head brush or cloth fixed on the end of a piece of wood.
Primary Cells may be classified into two groups; closed circuit and open
circuit.
Cloeesl CtrcnK Cella. — Cells of this group must be capable of work-
ing on a closed circuit of moderate resistance for a long period without sen-
sible polarisation. They must, therefore, contain an effective d^>olarizer.
The best depolarizers are copper sulphate CuSO^. strong nitric acid HNOst
chromic acid CrOg. oxide of copper CuO, and chloride of silver AgCl.
The following table contains data on the representative types of closed
circuit cells.
Name.
-fPlate.
Electrolyte.
Dei)olarizer.
— Plate.
E.M.F.
1
R.
Daniell
Zinc
Sulphuric Acid
Cop. sulphate
Copper
1.08
1.
(irove
((
»t ti
Nitric Acid
Platinum
1.9
.15
B onsen
it
11 M
(t «t
Carbon
1.8
.2
Peggen-
dorff
(t
4< If
Bichromate of
t<
2.
.2
Potassiura-
Sulp. acid
Lande
(t
Caustic Potash
Copper Oxide
Iron
1.
.1
Davy
11
Ammonium Chloride
Silver ChlorideiSilver
1.1
4.5
The values given as electromotive force and internal resistance of
the different types of cells are approximate only. The E.M.F. depends
upon the purity of the materials, the concentration of the solution; the
internal redstance, furthermore, depends upon the dimensions and general
arrangement of the cells.
BATTBBim.
>^«» Clvcalt Colls. — C«Ua ol Lhii group an only luitjible (or uaa nhcn
acting polariieT, aa tha affoct of polaruatiou can be takaa cara of durinc Uie
intcinlg of rrn. dlber by a ilow acting depolariio' or nven vithoui any
--'-^ — ■- '- >- ^rever, „[ the (raitat importMice that do local action
Sam..
-^^■"^
ElMlrolyte.
-Plate.
E.M.F
R.
Gaianar
ZlDC
OildeotZlDCMl-ani-
mooiac, Chloride or
BiDoiide or
Noae
Caibon
Carbon
13
'.i
Tha el
~ ~ ■.: (he »
(11.
"bhHstcoe," dieaolTed in wi
kbout 8 incbn higli and 6 inchea dismcLer. The
the middle, spread out, and set on ed£e in the
bottoTD of Ihe cell, tbe tenniaal bdng a piece of
ntta-percha inauiated copper wire extending up
tliTTHV> ^a aoiulion.
The nne ii usually cast with Bnicra spread out,
and a book for sus^enfliuf from tbe top of the iar
' — 1, the lamuial banc on top of tb« hook.
is aulphale o( ooppa, or
(•ee^.Z)iea Jaaa^c.
from
This U
, tbe top of t„_ ,_..
crystals src plac«d in the bottom of i... ...
tbe eoRMT, Ibe jar then being filled with water to
joM ■Dore the "crowfoot" or liac A Ubls-
ipDonfa] of Bulphurie add is added. A saturated
■ololioa of eoppcr sulphate forms aroiind the cop-
per; arui, ikfter use, a linc sulphate solution is
lotmod kround the side, and SokIs upon th« C(i>-
pa BuJpbatfl solution. The line of separation bet
■ called the bint Htu. As Ihe two eorutiooa are k
tbor diSerfml specific gravities, the name "gravity
This ceil does not polariie, and the E.M.T.a pra<
- ' ■ " - a eloani drcuit. If the cirei
■ not have work ei
— . __,_jn forming i_
ins an >ppearance^ike black mud.
Car« •# *hm tlwmwttr Csll. — For ordinarv
pomuls of "blnestooa" per cell is usually found ]
It is better to dean out the cell and supply new nolut
plrnisii "BhteatOD*" orrstals shaulil not be enulli. .
Urce BB «n egg. In good eoadilion the solulion at Ihn h-
j,^^^, ..,_. 3: : . ,„ .
copper dcpOBJIiog oi
"loBlworl
best. Whe
' about thr«
st»rtiny » new Mttterv ' -
farty-eigfat hours (o lo
LIT a layer of good
rhis oil should be
under •WO" F. H
liphkie and lower the internal resislance.
8VMUOLB, UNITS, INSTBUMKMTS.
■astAnce of the ordiDBir ffrmTity cfiU ii 2 to 3 ohmi. dcipaidii^
r oooditions, nich u the nM ol platn. Ibn nttmns LucMhcr,
Xk« CeclaMikd Cell.
Thifl «ii1 u cin« of the moet eommimLy lued outade of tedesraphy. and up
to the kdvent of the so-cklled dry cM wu prmcticall]' the only one in uh for
borne uid telephone work. The eLemeDta &re uno bud carbon^ with per-
oxide of mmgmngee about (ha carbon plate for a depolariuD^ e^*'^^' A#
luually oopjtrticted — for (here are maoy modififatioos of the type — the jar
u of guvBp about 7 iDchee hi^hand 5 inchee id diameter, ot BomeumeB h^uarQ,
loDgp ahd ie plaoed jq one corner of the jar in a solution of ^l-atnmoniao.
The oarbon plate is placed in a jwroiu cup withiD the jar. and the apace
olatad peroxide i^ oiaDganeiie, The nal-ammoniac aolution pasaee through
the poroiia cup and nuiBCei» the coDteols. Tliia cell will pdariie if worked
hard or abort dreuitad. but recuperatea quickly if left on open sircuit for
a while. The nnitance of the I«clspch^ oell vaiiei with ila nie and oon-
ditioo, butiasaunlly Im than one ohm. The initial ELM.F. i* about t^
volt. It ia dcainble not to u» loo stroac a ealutioo of aal^aimnKuiiac. ke
eryMali will be depoeited on the >ino; and nnt to Isi theaolutioa get too
weak, M ehlorida of linc will form on the linc: both eaaditioDi will
materially iacreaM the internal renstance ol the cell and impair iu
effiojenoy. nn**-™-* ^ — ■' — J: = ' — ■'- i' = * •^'~ --
cally pan line and a uu
in an electrolyte paale^
2i' long by |' diameter wilhtli^'
vBly used for teetJDK iiuulallr
e element* are a plate of chen
icted the jar ia of flas
B Fi«. 3. The paate ia pou
, .u«n hermetically Haled. The
rouj^h fiber tope ^ posts thereon.
I small sjie of the cell renders it pnasible to OOD"
■- containinjr box is providn with a pole-chan^
laired. Fig. 4 shows a portable testinc batt«ry
y of these cells complete roady for use.
I E.M.F. of the chloride of silver cell is .fl of
ind there is noloeml
The elements of this cell are linc in a dilute solution of sulphuric
BATTEKIES.
tir*raro»te of potuh. ooe mrt ■ulphurio acid, snd nine psrta water. Dii-
aln the bkbroiute in the watw at boiling, and when «wl add the sul-
ftarie aisd olowly. The line pl&te ia in the form of s cone, and ia plaCKl
■ lh> bottom at a poraiu eup inside a glau jar. The carbon plals u out-
br anaJnination, and the cup ii filled with a dilute Mluiion of aulphurio
•diL 1& outaida jar ii filled with the electropoin. In (hia the carbon
pU* m immcnad.
Tbe E.U.F. ia 2 volta, and thx intsmal |-«aiMance is about halt an ohm.
nc iDluIion is orisioally of an orange color. When thia becoRiea bluiah in
liM. add more cryitala. Bhould the color be notinal and the cell be weak,
■Id (raah anlpbune acid.
a C«U.
thia cell (Me Fie. S) are linc and copper 01
< a tl
L ataried. ia held in
it thia cell (Me Fie. S) are linc and copper oxide in a wal
e nnaah. The pIsteB ate suspended siile by side from t'
The copper oiide, which is plated with a thin Qlm of m
10 SYMBOLa, UNITS, IMSTKUMEMTB.
a tnine attuhed ta the coTsr. A 1>jar of oil U
Ins eilU. Tbe E.M.P. !■ law, etnitlng U .ts
era ohm for Ibe largesl cell. Verj Btrous cnr-
renu can be taken fruiu tbls cell : for laimnc,
tbe cell bBTlni an E.M.P. of .TS Tolt and rnlat-
ance of JTS oliia will prodnce 30 aaiperea on
Dtj BatMrlea
Tai^es illghdj In
Bur^lrtrdry cell Is madeof a Hoc tubedee Fig S) lu one element, vbieh acti
also a« tbe containing ]ar. a wrlion cjlluder ft th« negstite elemeut, and an
parte platter, J7 parti flour, and 2 part* water. In eoDBtructlng the cell'a
plnngergomeirliat larger than Che oaibon element iiplacDdiD tbe mldilla of
iJfe-
^
[
1
the lino Jar. ai
place, and tbe
on. 3 parts plaeler.
nl le fastened to
»n pUte. Tbe K.M.K. of the Bumler cell li 1.4 volt ; the Internal re-
Gamer diy otll, shown fn Pig. T, oonalits of a ilao cup as the posltl*«
up of the folium
BATTEBISB.
ClBik Cell.— The form i>[ celj called
Cbrk, necific&tiDru for mAkin^ whjch
nO be tound in tbe ehapter on udjU,
■ tbe <Hi« adopted as tbe vtandard of
E.11F. by tbe IntemationaJ Electrical
Coocnaa at Chicago in 1S93. The poii-
tai« to* and 26° C. the iiicr«» of 1° C.
deereaaee the E.U.F. .00115 rail.
Lalv inrestisatioos by the Phyiika-'
Tachniache R^ichnai
•f the E.M.F. a '
the eh*n^ due
oua I
15° C
llw Ciark~c^ great care must be~ taken
■Adent and from the Sot that the E.M.F.
bci behind the letoperature ch^^ise.
- — -—-'^■trk Ciell. — TCa.
Fla. 8. Cailiart-Clark Standard
the soiutioii of line eiilphalc la sal
■ad the temperature ooelGcLent
W«>o> CadMlaM Cell. ^ The elemente of
ud mtKcury. the eleetrolylm b«na ■•---■• " -
if the cadnuum sulphate crystal
cell has the ■atue elements
■ ■' ■ CC. ThBE.M.F. i
"- ■ 'lheCUrlt<
- ,- - 20* C
y the Wesi
I E.M J", n
( — 20° C.)"
^1 4^r 77'°" *H'Pi»n>- 'he mdmium iulphate ,
at ^ C. and has an il-M.F. ;^ I.OIBSS '- - -
' ™«*'='55;- The E.M.F. renmioB con
joesB of .0001 amp. ba passed throi«h tl
11 han largely siipereaied the Clark Tell b.
Its ooOBlancy and lis freedom from temp
«r*Mpiaf of Batterj Cell*.
D E.H.F,greftter than that of or
nold give an E.H.F. \ ^ f
■abof 14.
be dnirea to obt
Flo. 9. Battery Cells in SonH'
20
BYMBOLS, UNITS, INSTRUMENTS.
terminals to positlye terminals, and neeatire to negatire, adding their onr-
rents togetiier at the same E.M.F. as in Fig. 10 t>elow.
If still more current strength be needed, another series of cells may he
added, and their current added to the circoit, making three times the eorrent
of one series.
SERIES 1
— -^^ -_■♦• --+ r_4- -
- ♦ - 4- - 4- - V
Fig. 10. Battery Cells in Multiple
The reason for this is, that when two or more resistances are pJaeed in
parallel or multiple, the equivalent resistance is decreased, as is shown In
another chapter. If the resistance of one series be 10 ohms, the resistance
of two series in multiple would be one-half of ten, or 6 ohms ; that of three
series In parallel, one-third, or 3.33 ohms ; and of four series, 8JS ohms.
Let
E =. B.M.F. of a single cell,
r = internal resistance of one cell,
R — external resistance m a circuit.
Then for n cells arranged in aerie^^ the current which will flow will be
represented by the formula,
/ =
nE
nr-\- R
r-i —
E
If R is very small as compared with nr^ then / = - • or the current ia the
same as that from one cell on short circuit. **
If, as in telegraph work, nr is very small as compared with A, then
/= "jf * o^ ^^^ current increases in proportion to the number of cells.
The value of r is nearly inversely proportional to the area of the plates
when fronting each other in the liquid, and directly as their distance apart.
Therefore, if the area of the plate is increased a times, for one cell
/ =
E
aE
- + /?
a
r-i-aK
Let
Xziz the total number of cells in the battery,
fia = number of cells in each series.
Tip =z number of sets or series in parallel.
Then the internal resistance of the whole battery
Tur
To find the best arrangement of a given number of cells (N) to obtain a
maximum current (/) working through an external resistance {R), make
— = Rf or the internal resistance of the whole battery equal to R.
ftp
In any circuit /= -t——. :-— i and for any arrangement
voCAi resist.
BATTBRIES. 21
WlMn amnged for maximam corront through a glyen external resistance Ji,
«•= y— and np= y-^.
To find the greatest current that can be obtained from a given number of
eells {N ) through a given external resistance (/?>,
2 T i2r
Br
To find the number of cells in series (n«) and In parallel (rip) required to
! give a enrrent (/ ) through an external resistance (/?) and to have an efli-
cieaey (/»).
Efficiency F=: ^'temal work
' Total worlc
J*R It
^•a'+*) %+^
%p
The iatemal resistance of the whole battery is
mr Ri\ — F) . , n,EF
— "^ — - — = — and / :^
np F H
^IR ^ It
EF "'"~J»(1 — JO
KEACTRIGAIi MaA«lTltIir« lITSTMinHtKirai.
The electrical measuring instruments most used in practice are galvanom-
rwQutanoe boxes, condensers, voltmeters, anuneters, and vratt-
with Tariations of the same, such as millivoltmeters, milliammeters,
CtelrsusoBs
SLTe instruments for measuring the magnitude or direction of electric
Kots. The term galvanometer can also be properly applied to the many
types of indicating instruments, such as voltmeters and ammeters, where a
needle or pointer is under the influence of some directive force, such as the
serih'fl field, a spring, a weight, a permanent magnet, or other means, and
is deflected from zero by the passing of an electric current through its
Nearly all galvanometers can be separated into two classes. The first is
the maoing-needl* class. A magnetized needle of steel is suspended with
its axifl boriaontal so as to move freely in a horizontal plane. The suspen-
sioa is bT means of a pivot or fiber of silk, of quartz, or of other material.
The needle normaJly points in a north and south direction under the influence
of the earth's magnetic field, or in the direction of some other field due to
aojciliary magnets. Near to the needle, and frequently surrounding it, is
plai-^ a ooil of wire whose axis is at right angles to the normal direction of
the needle. When a current is passed through the coil the needle tends to
torn into a new position, which lies between the direction of the original
field and the axis of the coll.
The second class is the moving coU or d'Arsonval class. A small coil is
sespended by means of a fine wire between the poles of a magnet. Its axis
te normally at right angles with the lines of tne field. Current is led into
Che eofl by means of the suspension wire, and leaves the coil by a flexible
wire attached underneath it.
Tbe /Iffttre of merit of a galvanometer is (a) the current strength required
to eaiwe a deflection of one scale division ; or (6) it is the resistance that
mnst be Introduced into the circuit that one volt may cause a deflection of
dlTlsion. This expression for the delicacy of a galvanometer is
U:<1TS, IN8TKUMENT3.
InanlDcletit aiilcas tbe following quuitltfsa sr« sIbo elien : the Teeislwicf
ol the VHlTBiionieter. the dtiitaiica of tli« scale from the mirror, tha Bi>e ul
tbe Bufe dirlsluiia, and the Mms of vibration tl Ibe needle.
The lemitiveneti of a gftlvnnometor is the dlSerence ot poMntUl necea.
B*^ to be LmpreMed betweea tbe aalTuioiiaeter tensLiuJt In order to pro
dace adeSectlon ot one scale dlvisiun.
Movlsr*!'***"* ValvaaoBicters. ]
<a.) The Tangm Galra«omtttT. II the inside diameler of tbe coll vhieb j
■ arrounda a needle, held at lero by the earth's Held, be at least 32 times ttia '
length of ilie ueedle, then the deflectioni uf the needle which coireepODd to
different eurrent streuglha sent throiuh the colls, will be sncli tbnt the
current strengths will vary directly u the tnugenls of the angles o( defleo-
merlvmnch i»nl (or tlin nhiuiliiie uieasnremenl olourrent. IlhBE,howoTer,
of which are of uncertain magnitude; and.
rmore, for accuracy in [he reaalls yielded by It
tism. 1
rvlcinUy.
eiacl Ln^ivrledso of the lalue of the borlionta] component of the earth's
magnetism. Tills Quantity la condDually changing, and is atTected much
by the presenee ot large massn of iron and the eilstence of Leary cnrrenta
nsofa tangent galvanometer coll. In cen
iber of turns In the coll,
lortiil intensity of the earths magnetism,
ml Bowing In the coll [o absolute units, and
. Tftugeut UalyanomeU
oneformofthLlnal.
nrasnt. Tbs
rti rod to the cente
of which 1.
> lbs plane ot tbe m
oneendoftheqiuvrt
tube, l" fu-
tened a oomplei uF
Si'SC.
lectad mlnato tniMn
loae needles
&11 point §D tbs u
At the other end o
tba quarta
(nbelntaslsDedaalni
ilar complex
with the polarity rev
tbs too sompleiei
equal magnetfe mo
"thS'^'r^th";
fleld.nodlrootlfsM
on woDld be
felt. In fact, thli a
Btion IB lory
alion form.
vhal i< called an utaHc BVB ten).
Each magnetlo co
eloeed b«tveen tw
"^wSe col>"
ThefourcollBaiea
bInding-poBte. go as
Current i» lent thn
ugh them In
the proper illrsction
ineaehea«edsHectl
wSw no""BU.tlc'
fatlgne and
which la vsrj atron
K, i> used as
adju«tnble
on tbe top ol
M-Hi'.
fl,—,S
earth's fleld chu be
any extent. Under
»Te force Che sens
oHslllBt^nof iheiie<
XfiS::
long. Tbe limit of
la largely InBucncc
by tbe pa-
Hecclom of tbe nsedle are ob-
and scale. Flg.'tSahDWH^BUehTn
reflecta an iraage of the scale Into
Che objective of Che teleacope.
ContlnnouB worli with Ibe teV
Inly Cire«ome. Where much gal-
ne pereon, a ray of lliht from a
!ted as to be refleetetT from the
Such a lamp and scale la ahown
ulckly to reat when uoder tbs In-
r
24 STHBOLH, tnriTS, IN8TBOMBMT8.
lKiuilncLo««d chnxnlHr i
>Hdlal« Ineloced In & bniioT niiuig in ■ oiocE oi
Uoced bj the iDOTliig needle reftct upon It and
^B«t ofdelloney U required. In Ihe moal Mm
•ftbeaoll. Thiai
QALVAHOUBTERS. 26
me nifllhod of dunpEng mnat b« emploved. OlM
« vuB u iba moving syitem. and kllow It to iwlnt
Via. U.
km o4 gmlTUioDieler hu Ihs /olloirrng icood pcdnta : lt« rendlngn ace bnt
tiftatlv klf«ct«d bj the proaenca ot raMaatt\c subetuim in tlie Tirlnlty, uid
npnctlcsllTiodependeiiCoflbeeartb-ineld; Ibslai'trumfltit cm b«eBallT
mU d«Bd-bsm(; nnd many farmi ars not mucb nlfpcted by ilbcHtloDB.
B. U ahowi • f arm of D'Ationvsl galTnnumeter of blah wtiiilbirity, Tbe
(ibavD It tbe Hgbt) u iticloasdlii an alumlDuin lubo. Eridy cutreuta
''re iDdoead In tbia tube wben tbe cnll ^wingK. Tb?y Fnuae damping, Knd,
«k ■ pn^wr Ihlckneaa of tabe, Ebe gyitam may ba made apsrlodlc.
Bklltatia ^[vftoomelen are used for measurmg or cam
lectrietty such a< flow in drcuite when a ccinJenser ii
cue aux linkacea are disturbed. The time of osrilli
iwn Sl'tbe°nJIi3K
SYMBOLS, UNITS, IKSTBUHENTR.
All c&lyBnonMiun ha'
be Ions ms emnpanil with ihn di
iping or the nccdJe the eiuuititii
if half ths ugla of the fin
dumpinc. The rom
le with BaLvLDamftei
Tuter, by E. L. Nicbols.)
of m«iuu for MsiLy
bj m. r. Mortkrap.
(Abntraot from Tnnn. A. I. E. E.)
. hae dmrribed was devBloped to meat the frequent need
ud AccuTfttfily cv1ibrH.tiDg »]temiLtiDff-curr«it imitrit
voltmeten, irh&t?rer thor o&pacity.
ivfliiMB, and btnnp porfaotly *'i
with them it hoa an
le operatioD of Uie inaUU'
^. ^^
mail dqwndj upon the heating t
RererrinE to Fig. IS, two emsll
wire whBD shunlH are used, lie
0.158 in., beiDE held near their ei
medium ot heavy lesde and ■oI<lei
One faee of a email cirmlar die
St their middle point, a 0.5-in. ci
of ivory. D,
™lar mirror
being fastened to t>
QALVANOMKTEBS. 27
bca. Futcned >t the oeatEr of the ivory dink aad half ny bctmen lb*
warn. nbtD tha dulc ia id poution an tlio vim, is a xmall hook. To this,
tbougb the maliuin of a (hrwd. u futroeda imaJI ad J lu table spiral ■prins.
The small iTory disk malDtains iu posilioD by frictioa aad the leasion of
the sprins. Tho wires bend hack under Ihf tenaion of the apiing about
0^75 InTTrom the vertical. The ivory diak does not rent directly upon the
wirei but b^rs upon Okch win through the medium of a stoall agate stud
shaped like the hwi of a screw, each wire beiDg in the slot of the agate alud
which nets upon it.
Tub two iroiy damps holding the wires oeiu- their upper extremity are
made sepaimtely sdjuatsble in a vertical
direction by meana of thumbecrews which
pais through the hard-rubber top of the
mnmment. Springs • « preveat lost motion
doS. ' '""^ "** "" """^ "" "
The airannment of psrta above described
ii supported by a brass frame aud a circular
kaid-nibber top. This frame dropa into a
circular nickel -plated brass case (Fig. 17).
Ihe cue has a window in il directly in
faonl of the mirror on the smalt ivory disk.
Tig. 17 ihowi dearly Ihe arrangemant of
parts and Ihe appearance of the mstrument.
By means of the adjusting screws the
tension of the iwu wires may be so adjusted
(hat the plane of the mirror will be vertical
SHing which holds the mirror aeaiost the
wires. Nov if any dongation occurs in the
■ire on the tifihl, that side of the mirror
will be drawn downer back by thesprii^, or
a deflection to the right is obtained. Oke-
wisc if an oJoORation takes place in the wire
on Ihe left, the mirror will deflect to the left.
II, howevir, an exactly equal dongation Fio. 17.
plane of the mirror will not tilt but simply move back keeping psrallel to
If the mirror is obsirved with a tdescope and scale, say at a distance of
one mettr, very minute angular defiectioos of the mirror will be easily
observed, while a sinking back of the plane of t)ie mirror away from Ihe
sale will not be obeervable.
Now if an alternating current of unknown streogth be sent Through the
•ire A. the wire will e&ngate, deflecting the mirror toward the left. Pass
mtil Ihe deflection is reversed and brought back to lero on the scale. If
vhen the deflection is lero. and certain precautions to be staled later have
deal obeerred, the strength of the direct current is known. Ihe strenglh of
the alleniating currenl will also be known; for it is exactly equal to the
dimt current. This, howevs. is on the assumption that equal currents
throiyh the wirea A and B produce equal donKalinns of the wirra. I're-
'' Brough the circuit : it under theee
,. all, or only slightly, it provea th .....
y elougated by the same currnit strength. The I
"Tf'ihii;
eiwth of „
adjustable and measured dire
naling current for the pitrpose o
be not deflecled at all, or only slightfy, it provea that ihe
practically equally elougated by the si — '■■
this possible email deflection
diagram. W* and W4 reprc*
ahuDt, preferably of mangaain, having
28
SYMBOLS, UNITS, IN8TEUMENT8.
a negligible temperature coefficient, furnished with tap-off pointa c andd,
between which the resistance R has previously been determined. The
ammeter indicated in the diagram wiU measure from one to two amp«r<M
of direct current; r, is a slide wire resistance along which a slider p may be
moved, thereby varying the pressure difference at o-o from sero to ine
value of the electromotive force of the storage battery- .* u — . i-^^-
The pointa a, b, on the direct-current side of t*^«_«»^*J.^,T5«l!SJ
attached to them which go «ther to an accurately cahbrated direct-current
laboratory standard voltmeter, or to a potentiometer.
Mwem
POTtNTIOMITIII
MTIMATINO- BURMNT tlM S DmECT-CUMUMT MM.
Fig 18.
When the instrument is installed, a permanent adjustment of the
sistancee at any convenient temperature of the wires and leads must be
made as follows: (see Fig. 18.)
The resistances, 9 td 10 = 7 to 8,
inorwwwMi*, ' 10 to 1 + 9 to 6 = 8 to 4 + 7 to 2 and
2toc + 4tod = 3toa-h6to6.
Thus while this gives the over-all resistance from a through the wire W^
to b equal to the over-all resistance from d through the wire Wm to c, the
different portions of the circuit must be matched in resistance as stated
* When the switch S is closed on the alternating-current aide the two
wires Wm and Wd are thrown in parallel, and the two parallel-connected
circuits have the same resistance, by construction, and that to th«e par-
allel circuits at the points 2 and 4 is apphed the same potential difference,
this potential difference being the drop on the low resistance R carrying
the alternating current. The drop over R, inasmuch as it is a low resis-
tance, is only slightly lowered by being shunted by the two wires of the
instrument and their leads, and this lowering of the potential is not apore-
eiablv greater when the two wires in parallel shunt the resistance R than
when only one wire with its leads shunts the resistance. Disregarding
the slight lowering of the potential, both wires will now have passing through
them equal currents, each current being nearly the same a« would pass
through the one wire Wa if the switch S were open, and only this wire could
"^With^he resistances of the parallel circuits correctly adjusted to equality,
both wires will get equal currents, both will elongate equally or very nearly
TO and the mirror m instead of rotating will move back, maintaining ita
Skne narallel to the position which it has with no current passing.
"^ When Oie switch Sis thrown to the direct-current side, the potential
drop over the resistance R is now applied to ^^e wire f^- only; and tj^^^^
potential difference between the points o and 6 is applied to the wure W^
OALVANOHXTBBA. 29
uid b eui be Tkriad by the ■Udo' p aod ammr«d by
-.: .^ ■pplisd at a, b. Tbe aDimMer livca Iba
Tba ahuDt rMiataaw R nuy b« dcaisD«d to carry any ourrsDt, howsvv
lai^ Tha niiH nauMnce K, or a oombinatloii of lenaiaactB, niay be
densmd with aaml tap-off or potential iioiDts. k that the inaCrument
attj slway* have approximately tbe same poleolial applied to itg alier-
natinC^urreat aide, whaterfr tbe atrcDglb ol the current to be meaaured.
Tbie potential drop la beat made between 0.2fi and 0^ volt. Tba necee-
tmrj drop of poleotial bcuif ao to*, tbe eoercy djsaipated in the ahiiDU
ia •mail, and thereton thcv may be of very moderaM tla». It ki alto euy
to laakB them prmotietUly luui-iDdDetive^
OKlvsHaBantev •>>!*( B*xaa.
II I* nften dealr«bl* to nae a iialvjuiameter ol high gentlbllltT for work
ilwBiiaillin a mach lower unalbiniy. Again, it may be conienlent to oall-
°^:
1. Es;;:%r
_— AAAAAA 1 CoDTentencB dt
"''''*'' Die ratios be
lOD, and 1000 ; that ia i, A. or .1,,
t to go throuffh the galvanometer wblle
■buDC. lnfT(.l*let
al eorrent flowing In the drcalt. and
rt flowing thrDagb tbe galvaoometer,
= g- + I = tbe MaUiplymg potcrr of tbe •boDt.
nlwUch will give a certain multiplying power, h, la
aqoal to ^^^1 ■ Fig. » abovi a form
o( ahnnt need with a galvanometer, al-
tboBch it la perfectly teaalble to oM an
ordlnarr realatauoe box tor the poipoae. i
Hewn, Ayrton & Mather have developed I
anew ihunt, which can bt uaed witb any <
gatraitometer Ineapective of Ita reaiit-
anee : following li a dlagrmu of It.
A and D are termlnala for tbe galvano-
golng and outeolng terminal! for battery
clrCDit. To abort olrouit G, place pluga
In j and f. To throw all tba current
thronch G, put a ping In t only. To lue
Ibe (honte, place a plug In b, and leave It
thereaDtilthrDngbiuing. Inthiimelhod
o( eitber" O or r. Tb^abunt ^i can
therefore be uied with auy galvanometer.
Tetnpeirature varlatlone make no differ- ~
•nee, provided thev do not take place Pio. 20.
dnring one eet of teau. The reelitaiics
r may be auy number of ohiff, but In order nnt to decreue the •enalblllt)'
too Dneh r abould be at leaat aa large aa Q. The rnaiatance r ia divided tor
IH* aa followa : permanemt attaebments to tbe various blocks are made at
point) In the eoll oorretponding with ^^ j^ r^ obmt.
MBOLS, UNITS, INSTRUMKNTS.
-^ |/WVW,
AyrtOQ A M&ther's Univcml Shunt.
PRACnCAl. •TAHDABUB OF RKSISVAVCB.
Conduct^™"). Flatipoid is
ItsntUnl. of v«rioiu> conveni
«,.th
ted by Ibe rai>-
umno
mercury 106.3 pro. long
hcrefore Becondary stn
dards
rdi»J
will, a great dfKftw o
nude
»nd o
of wire. The iriitoria
f resLstivily. mini hav
> aTr
poaHn perma-
all temperature
ty, m
luit liave . smaJI then:
OD-elec
lOuldhavearBirlyliich
xaa bU nf Iheie quali
n (MH
^iCS^
po!d"
^^hio f'-«l^^^)'j__'^v -f^"
.sn:'Si-^°.'
I It*™
adopted by lh«Ph™ka
y law raittancM havm
i,chR
For ve
B'Wb
BE8I8TAKCE8.
31
^
in T»IuM of .01, .001 and .0001 ohm. the redBtanoes beinc that between
toe two amall binding posts called the potential terminala.
The farm of reeietanoe box most frequently met with is some type of
wjeatstone's bridge," the theory of which U described elsewhere.
The ooils are usually of silk insulated wire wound non-inductivelv on
ipoob, with the ends attached to brass blocks, so arranged that brass
phigB can be inserted in a hole between two blocks, thus short-circuiting
the reostanoe of the particular bobbin over which the plug is placed. By
Qoo-iodu^ye winding is meant that the wire is first doubled, then the
dosed end is placed on the bobbin and the wire wound double about the
bobbin. By this method any electro-
BBipetie action in one wire is neu-
trahsed by an equivalent action in the
other, and there is no inductive effect
when the circuit is opened or dosed.
The ixMt-office pattern of Wheatetone
brifbe is one of the most commonly
osed, a diagram of ite connections being
down in Fig. 24.
Ooe arm of the bridge has separate
reoftances of the following values:
1,2.3. 4. 10. 20. 30. 40, 100, 200. 300,
«0. 1000, 2000, 3000, and 4000 ohms.
AiMtherarm is left open for the unknown
reristance. z. which is to be measured.
The remaining two arms each have three
nantance coils of 10, 100, and 1000 ohms
wroeetively. Two keys are supplied
vith the P.O. bridge, one for dosing the
battery drcuit, and the other for dosing
the galvanometer drcUit. The battery
key should be closed first; and in some
Flo. 26. Diagram of Anthony Bridge.
32
SYMBOLS, UKIT8, IKSTBUHSKT8.
i
inBtnimentB the two keys are arranged with the battery key on top of
the galvanometer key, ao that but one finger and one pressure are necessary.
Prof. Anthony hais devised a resistance box in which there are 10 one
ohm ooils, 10 tens, 10 hundreds, and 10 thousands. Any number of any
TBM .lUT* «K>up can be connected either in series or in
TENS UMTS multiple. The means of accomplishing this
^w^ Xf'^L- *™ •**'' clearly in the cut.
irc5*
]>«ca4e Methods.
The Wheatstone brid^ arrangement has
the disadvantage of requiring a large number
of plugs to short-circmt the resistances not
in use. which introduces an element of uncer-
tainty as to resistance of the plug eontacts
and the necessity of adding up the values of
all the unplugged resistances in order to deto--
mine the value.
7 So ^^S- 26 shows the Weston arrangement of
Sr 91 coils requiring but one plug per decade and a
small number of coils.
In a later decade arrangement by Leeds ft
Northrup, 1, 3, 3', and 2 ohm boils are con-
nected in series as shown in Fig. 27.
Let the terminal of the 1 ohm coil and the
2 ohm coil and the points of union of the
Fio. 26. Decade Resist-
ance Box.
coils be numbered (1), (2), (3), (4), (5) as shown in Fig. 27. The current
(1) and leaves the coils at the point (5) traversing 1, 3. 3'.
2 = 0 ohxns in all. If this series is multiplied
enters at point
1 (i;
AAAAAAAA/W— +
C2)i 3
VVVVWVV\4
by any factor n, then n (1 + 3 -f 3' + 2) =rn
0 ohms. It will be seen that if the points
(1) and (5) are connected all the coils are
short-circuited and that the current will traverse
sero resistance. If the points (2) and (5) are
connected the 3, 8^, and 2 ohm will be short-
circuited and the current will traverse 1 ohm.
By extending this process so that we connect
two and only two points at a time, it is possible
to obtain the regular succession of values
n (0. 1. 2, 3. 4. 6, 6, 7, 8, 9) the last value
being obtained when no points are connected.
The following table shows the points which
must be connected to obtain each of the above
values and the coils which will be in circuit for giving each value:
3'
(41
C3)
(5)
Fio. 27.
Value.
0 =
1 =
2 =
3 =
4 =
6 =
6 =
7 =
8 =
9 =
Points Connected.
(6-1)
(2-5)
(4-1)
[l-t]
(1-3)
(2-3)
(5-4)
(1-2)
(0)
CoUsUsed
0
1
2
1.2
1.3
3', 2
1, 3', 2
1, 3. 3'
3, 3', 2
1, 3. 3'. 2
Fig. 28 shows a method of connecting these points two at a time with the
use of a single plug.
The circles in the diagram represent two rows of ten brass blocks each.
To the first two blocks at the top of the rows, the points 5 and 1 of dia-
gram 3 are connected, to the second two points 2 and 5 are connected and
RHX08TATS. 33
» OB, DO pointa bcins oonnectad at tba Inat PBir of bUwkK. It ia «vid(cit
tbat i( s. idue b« LiuerUd betwem the blocks 1 and iS, ibe poiuW 1 stul 6
of dialcrun 3 &rfl connected ^riog the vulue 0; if between the btocki 2 AOd
5» the pointB 2 mnd 5 aie ooaueoted Eiviag tbe TaLue 1,
•ad ao on. The vklue 9 is obtaiDRT when the plu( ii
diapoaad of by beans ioasrteil in the laat ptii of blooka
Id tartins dyoanua and other dactrioal apparstiu
prodqeiD|c }MTgn aiz»unta of enarn', it ia nBoeflavy to
UTO rtBiataacea of a capacity Humdebt t^ absorb the
efiern dsrelo[ied. and thii ia almost invariably done
br iba uaa ol the watbs anEoerAT. wbicH in ita
MUpleat EarEaT eDnaiata of a box or barreJ of wood, in
wiiieh are placed two matal eleetroda Hhiebcsti tw
adjuatai in nlation to each other ao as to increaaa
er aod horiaonULl aleotnxiea,
(b) aama jar aod (daetrodee u above,
nUr uaed; 11 ampereB.Tvo]ta, electrodeeZ]
tan nM to 122>T. and wag slowly rinng i
(e) Wooden trough '42* X «' X 8', vertioal sheet iron electrodes; oroeB
■eetHin of liquid, U iq. in. Witb 10% solutioo of salt water, and lOampens
flowing, temperature at end of run 85° F. Electrodes 411' apart, P. D.
X> Tolta, Current deneity, about 1 amp. per eq. in.; watta aosorbad, .11
watt per cu. in., would probably larry 13 to 15 amperee safely.
It u appaiAnt that salt increases the ourrent canning opacity, but
deerrasea watts abaoriied per cu. in.
(d) WUaka)' barrel filled irith clear watar, Eleotrodat were boriioatal
drcaW inm platea A' thiek. Plataa 20|' apart, P. D. of 486 volta gave
e«KTBit of 2^ amperea. With platea I* apart, P. D. of 2ZS volt« cave
3G,5 ampena at tha tnd of one hour. When temperature of the watar had
n»ebed 179° F., much taa was civeo off. Current density ,12 amp. pet
aq. in., and watts absorbed 30Ji per cu. Id.
iVith laiie current dauaity aiid dir«t currait there is much deoompo-
trodca are not to bo nooDUaanded uulees a large niunber of liol« are drilled
throDcli tha top plate to allow escape of as. It Is seldom neoeaaary to
nae Mronfer nhitioD than 2 or 3 per cent of salt, and in adding salt to tha
rheostat It.ia beat to dissolve it thoroughly in a separate Tseeel and then
add to the liquid aa needs). Liqind rheostats seem tn be mare satisfas-
BD decompaailion of alectrodn ti
RaaaHs ar« based upon a volum
34
SYMBOLS, UNITS, INSTRUMENTS.
Water and DiluU Sulpkurie Acid.
Water and Common Table SaU,
Per Cent Acid
Resistance in
Per Cent
Resistance in
by Weight.
Ohms.
Salt
Ohms.
.174
4.12
by Weight.
.435
1.75
.23
7.84
.724
I.IQ
.46
4.65
.986
.85
.70
3.12
.93
2.38
1.16
1.90
1.39
1.48
Use of salt solution is cheap and convenient, but very untrustworthy
for accurate work.
For the sake of convenience in choosing proper sises and loigtha of
iron wire for submerged rheostats, the accompanying table is given. The
safe carrying capacities are the currents the wires can safelV stand for a
continuous run. If the apparatus is to be used for short p^ods, as in the
case of a starting rheostat for a large motor, these values may be doubled.
Water should be kept circulating through the barrel, enough water being
used to keep the temperature below 200^ F.
of Oalvaalaetl Iron ITlre.
niieoiktialrii.
For SabMoiiped
Wire
c^ #
Minimum Length in Feet for Safe carrying
Num-
Safe
•
Capacity at Different Voltages.
T9 A
1 ,_ .
carrymg
Capacity ;
Feet per
Ohm, not.
bers:
Gauge.
Amperes.
100
110
220
500
20
36
22.8
25
50
114
8.5
19
42
24.6
27
54
123
10.4
18
50
26.4
29
58
132
13.5
17
60
27.2
30
60
136
17.1
16
71
29.0
32
64
145
21.6
15
88
31.0
34
68
155
27.2
14
103
32.7
36
72
164
34.2
13
122
34.5
38
76
173
43.2
12
146
36.4
40
80
182
64.3
11
173
38.2
42
84
191
68.6
10
205
41.0
45
90
205
86.5
9
245
42.8
47
94
214
109.1
8
293
46.9
52
103
235
137.5
7
347
60.1
55
no
250
173.5
6
412
53.1
59
117
266
219.0
5
489
56.4
62
124
J?82
276.0
4
584
59.5
66
131
298
348.0
CONDENSERS.
S5
If one terminal of a source of E.M.F. be connected to a oonduotor»
and the other terminal be connected to another conductor adjacent to the
first but insulated from it, it will be found that the two conductors exhibit
a capacity for abs>orbing a charge of electricity that is somewhat analo-
gous to the filling of a pipe with water before a pressure can be exerted.
The ehaiige will remain in the conductors after the removal of the touroe
of supply. This capacity of the conductors to hold under a given E.M.F. a
cfaarge of electricity is governed by the amount of surface exposed, by
the nearness of the surfaces to each other, by the quality of the msulating
material, and by the degree of insulation from each other. If the ter-
minals of a battery be connected through a battery and sensitive gal-
vanometer to a long submarine cable conductor and to the earth, it will tie
found that a verv considerable time will elapse before the needle will settle
down to a steady point. Tliis shows that the cable insulation has been
ftiied with elc(:tricity; and it is common in so measuring the insulation
resistance of a cable to assume a standard length of time, generally
three minutes, during which time such electrification shall take place.
A condenser is an arrangement of metallic plates and insulation so made
ap that it will take a standard charge of electricity at a certain pressure.
Toe energy represented by the charge seems to be stored up in the insu-
lation between the conducting plates m the form of a stress. This property
of insulating materials to take on a charge of static electricity is known as
inductive capacity, and the following table shows the specific inductive
eapacitiea of^ different substances.
Specific liidactlT« Ciapaclty of Oiaaea.
(From Smithsonian Physical Tables.)
With the exception of the re8ult« given by Ayrton and Pebrt,
for which no tempebature record has been found, the
values are for 0° c. and 760 m.m. pressure.
Gas.
.4ir
Air
Air
r«Tbon disulphide
Carbon dioxide, COg
r&rbon dioxide, CO«
CarboQ dioxide, CO*
Carbon monoxide, CO ....
Carbon monoxide, CO ....
Coal gaa (illuminating) ....
Hydrogen
Hydrogen
Hydrogen
Ni'troua oxide, N^O
Hitroua oxide, N«0
Sulphur dioxide
Sulphur dioxide
Vaeaum 5 mm. pressure . . .
VaeuunaO.001 nun. pressure about
Vacuum
Vaeaum
Sp. Ind. Cap.
Vacuum
= 1.
1.0015
1.00059
1 .00059
1.0029
1.0023
1.00098
1.00095
1.00009
1.00069
1.0019
1.0013
1.00026
1.00026
1.00116
1.00090
1 .0052
1.00955
1.0000
1.0000
1.0000
1.0000
Air=l.
1.0000
1.0000
1.0000
1.0023
1.0008
1 .00039
1 .00036
1.00010
1.00010
1.0004
0.9998
0.99967
0.99967
1.00057
1.00040
1.0037
1.00896
0.9985
0.94
0.99941
0.99941
Authority.
Ayrton and Perry.
Klemencic.
Boltzmann.
Klemencic.
Ayrton and Perry.
Klemencic.
Boltzmann.
Klemencic.
Boltzmann.
Ayrton and Perry.
Ayrton and Perry.
Klemencic.
Boltzmann.
Klemencic.
Boltzmann.
Ayrton and Perry.
Klemencic.
AjTton and Perry.
Ayrton and Perry.
Klemencic.
Boltzmann.
36
SYMBOLS, UNITS, INSTRUMENTS.
Bpmmmm Indvctfre Cmp^uAtj of AolMa (Air Vaity).
Substance.
Oaloflpar parallel to axis . . .
Oalospar perpendicular to axis
Caoutchouc .....
Caoutchouc, vulcanised
Celluvert, hard gray
Celluvert, hard red ,
Celluvert, hard black
Celluvert, soft red .
Elbonite .
Ebonite .
Ebonite .
Ebonite .
Ebonite .
Ebonite .
Ebonite .
Fluor spar
Fluor spar
Glass,* density 2.5 to 4.5 .
Double extra dense flint, den-
sity 4.5
Dense flint, density 3.66
Light flint, density 3.20
Very light flint, density 2.87
Hard crown, density 2.485
Plate, density
Mirror . •
Mirror . •
Mirror . •
Mirror . .
Plate . .
Plate . .
Plate . .
Guttapercha
Gypsum .
Mica . .
Mica . .
Mica . .
Mica . .
Mica . .
Papa% dry
Paraffin .
Paraffin .
Paraffin .
Paraffin, quickly cooled trans-
lucent.
Paraffin, slowly cooled white .
Paraffin
Paraffin
Paraffin fluid, pasty
Paraffin, solid
Sp.Ind.Gap.
7.6
7.7
2.12-2.34
2.60-2.94
1.19
1.44
1.89
2.66
2.08
3.15-3.48
2.21-2.76
2.72
2.56
2.86
1.9
6.7
6.8
5-10
9.90
7.38
6.70
6.61
6.96
8.45
5.8-6.34
6.46-7.57
6.88
6.44-7.46
3.31-4.12
7.5
6.10
O •«)' '4 .17
6.33
6.64
8.00
7.98
5.66-5.97
4.6
1.25-1.75
2.32
1.98
2.29
1.68-1.92
1.85-2.47
2.18
1.96-2.29
1.98-2.08
1.95
Authority.
Ronuch and Nowak.
Romich and Nowak.
Schiller.
SchUler.
Elsas.
Elsas.
Elsas.
Elsas.
Rosettl.
Boltimann.
Schiller.
Winkelmann.
Wullner.
Elsas.
Thomson (from Herts's vi-
brations).
Romich and Nowak.
Curie.
Various.
Hopkinson.
Hopkinson.
Hopkinson.
Hopkinson.
Hopkinson.
Hopkinson.
Schiller.
Winkelmann.
Donle.
Elsas.
Schiller.
Romich and Nowak.
Wullner.
Subnuuine cable data.
Curie.
Klemencic.
Curie.
Bouty.
Elsas.
Romich and Nowak.
Abbott.
Boltimann.
Gibson and Barclay.
Hopkinson.
ScluUer. t
Schiller.
Winkelmann.
Donle, Wullner.
Axons and Rubens.
Axons and Rubens.
* The values here quoted apply when the duration of charge lies between
0.25 and 0.00005 of a second. J. J. Thomson has obtainea the value 2.7
when the duration of the charge is about A X 10* of a second; and this is
confirmed by Blondlpt, who obtained for a similar duration 2.8.
t llie lower values were obtained by electric oscillations of duration of
charge about 0.00006 second. The larger values were obtained when
duration of charge was about 0.02 second.
1
C0NDEN8BR8.
37
■pMlfle Iiid«c*lve Capocttj of Solids (Air 'WJmlktj). — Oont.
Substance.
Sp.Ind.Cap.
Authority.
Poredain
4.38
4.55
4 ^
2.48^2.67
18.0
5.85
10.2
3.10
3.67
2.96-3.73
2.18
2.25
3.84-3.90
2.88-3.21
2.24
2.94
Curie.
Quartx, along the optic axis
wrti, tranar^ve
Resin
Rock salt
Curie.
Curie.
Boltsmann.
Hopkinaon.
Curie.
Rock salt
Miminin . . ^
Rrktninh Anrl Nowak.
Shellac
Shdlae
fteflac
Spermaceti
Spermaoeti
Sdphur
Sulphur
Solphur
Winkelmann.
Donle.
Wullner.
Rosetti.
Felid.
Boltzmann.
Wullner.
J. J. Thomson.
Blondlot.
Sulphur
2.56
Trouton and Lilly.
•pociflo iMductiire C»paci^ of Iiiqnida.
Substance.
Akohola:
Amyi
Ethyl
Methyl
Ptopyl
Anifin
Beojene
ficDMne averaM about . . .
Benaene at 5** C
Bcaune at 15** C.
Beoaene at 25** C
Baueoe at 40<* G
Hexane, between 11"^ and 13<* C.
Ortane, between 13* .5-14* C.
Decane, between 13* .5-14* .2 C.
imylene, between 15* -16* .2 C.
Octytene, between 11* .5-13*
.6C.
Dieeylene, between 16* .7 C.
(Xk:
Aiaehid
Ckstor
Golia
lAHDOn.
Neatafoot
vJDTe .. .••••*..
FetixMecmi ....••••
Petroleum ether
Rape-eeed
Seaame
Sperm .. ........
TarpcDtine
Vaadine
Oiokcrite • .r . .
Toluene
Xjieue
Sp. Ind. Cap.
15-15.9
24-27
32.65
22.8
7.5
1.93-2.45
2.3
2.1898
2.1534
2.1279
2.1103
1.859
1.934
1.966
2.201
2.175
2.236
3.17
4.6-4.8
3.07-3.14
2.25
3.07
3.08-3.16
2.02-2.19
1.92
2.2-3.0
3.17
8.02-3.09
2.15-2.28
2.17
2.13
2.2-2.4
2.3-2.6
Authority.
Cohn and Arons; Tereachin.
Various.
Tereachin.
Tereachin.
Tereachin.
Various.
Negreano.
Neereano.
Negreano.
Negreano.
Landholt and Jahn.
Landholt and Jahn.
Landholt and Jahn.
Landholt and Jahn.
Landholt and Jahn.
Landholt and Jahn.
Hoi>kinBon.
Various.
Hopkinson.
Tomaszewski.
Hopkinson.
Arons and Rubens; Hopkin-
son.
Various.
Hopkinson.
Various.
Hopkinson.
Hopkinson; Roaa.
Various.
Fuchs.
Hopkinson
Various.
Various.
38 BVUBOLS, UNITS, INSTKUHBNTS.
■peclflc iBOBCtl** C«pt>cltj-, — I>efinilion: The ipecific iodueUyi
spsdty of Ihe suhaUncF with vhith ii
1). of one voU. The rorfEoicE nr* tables
en fmiti "»mi1hsoni>n TaLles''
of pnper cubits viiri« from 3 to 4. ko
niitture silopieil. The induFiive caueiiy
3 lo 3. oQcordmit lo its origin; and mii-
rile. and olher materials have a capkdl}.
itnole. lubricBting oil 55 pane, roiia 6«C,
mdard inductive ca parity of 3.6^ oxidiud
- _ pitch 70, have 4.4; ArkangH pitch it nelf
.^e 5.9: a mixture with GBllipot. instead of rosin — for exampte, Callipol
eOO. Arkaogel pilch 1 10, and Unseed oil 130 — hsi 4,8; n miiiure of lubri-
cating oil 9. rosin 52, blark owke.ite 23. white oiokerite Itl, has only 3.55.
The unit of canictW I9 the inleinalional larad. ohii-h ii defined u Ihe
capBcity of a condeneer wliirb requira one coulomb (1 ampere for 1 second)
lo raiso its potential from lero lo one volt.
Fioa. 29 and 30. Standard Condensors.
As the fvad in far larger than ever is met in pracllce. Ihe ]
min'o-farads or frattioiii. of (he same. Fig.
ao [■)iows the ordinary ) micro-
farad coniicDaer. anil Kik. 30 one that ii t
..Ijustable (or different valuer.
Diagram 31 showi an outline of Ihe Conner
lions inside an adjustable con-
T is most usually made up of
ler by some insulator such aa
sheets of tin toil neparalel from each oth
paraffined paper or mica. Every altemalp
sheet of foil is connected lo a
aimmon terminal. As the eatwcily of a on
ness of Ihe conductors to each oilier, and u
pon Ihe aru of llie same, the
^ and still be safe from kakase
insulating material is mode Di thin aa ptmibli
or puncture. Many oheets of (oil are joinni
tocelher ss d«cril.ed lo m^iEe
la™a"« M'p^iat^ inio bliidi<S.
CONDBHSKKS.
i
Fio. 32. HodUled Mftscart ElecCrometeT.
r
4U BTMBOI^, UNITS, INSTRUMENTS.
mnd krrucsd k> that bdv of them «an be iduned in or ont to add to or
IsMan the total capaaty. If connected in tnulliple «■ shown, or if Iba
poeitive Bde of one condeiaer be eoDoecled to the nwative aide of utotber,
or a number of them are thiu added together, then the condetLsn are aan
to be Brraaaed in "cuoade" or in aerin. Thii ia seldom done unl^ it b*
to nbtiun ir«tor variation in capacity.
Elect r«aH«ter. — Another uutruraeut uied whsr* i,„ u„vu>
eleetnacatie capaaliea or potaatiala is eonunon, is the rtectmnitltT.
"ho wSTi"
L. The
mi each other. Oiifntito
guadnuita are connected by
nne wirea. A eharee of riec-
oonneotinc tba ■uspcosioD
GlamaDt with a Leyden jar
If the needle be oharKed
poaitivelv it will be attracted
by a ne^tive charge and r^
pel led by a pontive charweu
If, therefore, thire ba a At.
lero. The usual mirror,
scale. s,nd lamp are uaod
with this iostrumenl.
Sown in Fi«.'32.
>0 T*lt-
Fio. 33. Kelvin's ElectroeUtie Voltmeter. ^ modificaOon of the els
ins high, and in aome «hb tow, altematii
trostaliD voltmeter of Lord Kelvin. It
In the high potential inslrument. Fig. 33. the needle is made of a thin
aluminium plale suspended vertically on delicate knife-edgea. with a pointer
extendiatf from the upper part to a scale.
On oilher side of the needle, and parallel to its faoe, ate placed two
quadrant ptila metallically connected snd serving as one terzninal of the
terminal. Any electrical potenlial dilferencB between the needle and tha
plates will deflect the needle out of its neutral pantion. Calibraled weights
can be hung an the bottom ol the needlo to change the value of the acslo
TOK.I'nfBTBHS.
These are indicating instruments which ahow the eleetroDKitiv* force
impraseed upon their lermimils. They are, in nearly all casae, caUbrated
cafvanomptera of constant high reaiatance. When eonneetsd across the
terminals of any aouree of electromotive force, currents will flow through
them which are directly proportional to the Impressed voltocca. A pointer
connected to the movrng element moves over a st»Io which is empiricelly
graduated to ahow the impressed voltage. The reaistanoe of eommeroid
^
CONDENSERS. 41
ToUmetcn in ohms varies from 10 to 160 times the lull scale reading in
voHs; thus, a voltmeter of Weston's make having a range of 150 volts may
have a resistanoe of from 15000 to 325.000 ohms. The reaistanoe should be
vouiid non-induetively and of a wire possessing a negligible temperature
qpfcffideat. The coBtrolling or directive forces to Ining the pointer back to
sero are gensrally obtained from springs or gravity and occasionally from
murneta.
Inece are several types of voltmeters in commercial use, those devel-
oped by Edward Weston being j;>erhap8 the best known. For direot-
cuneat measurements in either switchboard or portable forms the moving
coil type constructed on the general principle of the d'Arsonval galvanom-
eter with pivoted coil is most frequently used. They can be constructed
nss to have high remstanoes and perfect dam|>ing and are but little affected
by eztstnal fields, especially if shielded with iron casing, as is often done
whb switchboard instruments. .
For altemating-ourrent measurements the electromagnetic or soft iron
iBftniment is very commonly used for switchboard work. ^ In this instru-
moit a mass of soft iron is so placed in a solenoid that it will be drawn
irom the center to the edge of the solenoid, or drawn into the solenoid from
•a outside point. These instruments are correct only for the particular
freqaeney for which they were calibrated and corrections should be made
for sny change of frequency. When properly calibrated they may be used
OB direct-current circuits.
Pbrtable voltmeters for alternating-current measumnents frequently
enq>by a sjrstem based upon the electro-dynamometer. This instrument
lai the advantage of being independent of frequency variations or wave
fona. It can also be used' for cUrect-current measurements if correction
(or external fields is made.
la addition to the above types, voltmeters are constructed on the hot
wire principle in which the passage of the current causes heating and a
muequait expansion of the wire tnrouffh which it passes. The expansion
of the wire is taikexk up by a spring which causes a pointer to move across a
mduated scalei
The ecale of a voltmeter may be graduated and marked so as to indicate
the value of the currents passing through it instead of the volts impressed
ignn iu terminals. It will then be an ammeter. To be of value its
nsntanee must be small. Many ammeters consist of moving-cpil milli-
voltmeters oonnected to the terminals of shunts through which the
comnta to be measured are passed. The shunts are made of a high resist-
•ace kiw temperature coefficient alloy and. since the resistance remains
eoostant. the drop in potential between its terminals will be proportionate
to the current flowing through it. The scales are graduated so as to indi-
tate the currents passing through the shunts. The shunt type of instru-
neat is particularly applicable to switchboards, but is adapted for direct-
cvrent measurements only.
For altemating-curreat measurements the electromagnetic systeni is
RMally employad. the total current to be measured passing through a
bv<resistanoe solenoid, or the current flowing through the ammeter may be
redwed by inserting the primary of a series transformer in the mam circuit
•ad eonneeting the ammeter across the terminals of the secondary. Since
theatio of current in the primary to that in the secondary is constant, the
iaimeter may be calibrated in terms of the primary, but need have only the
mall secondary current flowing through it. «^ :« „ r«o«
••ft IroM lMatmai«Bt». — If a piece of soft iron be pUced in a mag-
»e«ie fieM it becomes itself magnetic. This fact is utilized in the so-called
"soft iron" instruments in wKch the movable system consists of a. soft
iron needle pivoted within a coil and normally placed oblique to the direc-
tioaa of its magnetic field. When a current passes through **»« coil the
awdle tends to assume a position parallel to the lines of force, and being
«»t«>lled by a spring or other controlling force, the deflection is a measure
ThL^^SS^oflmrSSmcnt is used to some extent for switchboard work,
but eamrot be used in measurements where great accuracy is reqmred on
MBomt of magnetic lag in the iron.
>
SYMBOLS, UNITS, INBTRUHENTS.
- throuffb two ooilB of ivirB, which ars caeai
h othsr. they will lend to place themidw
40TI. The Biemen'i eJ«ctro-dynunar
mmoatiued. It connaU of a fixed o
nf a few lurns of heavy wire (or heav
aDd another ot many tun
ibleof
Sfi'
i Ihereto, ig >i;
nil of few Cur
lial the degreefl
The["iower ende of the
lion with the Bsed
Bows throiwh the
IS pontioD at risht
of angle through
t dependinc
■prina, / iB^hl."" *"
the angle of defiecli
of the
Tent, and d be
The eleetro-d;
'tematin, ^„,„_
. alao di
Item* tint eurrenia o(
myable roll ol the eleclro-djmamometBr be of
led roil be ol heavy wire, then the imtruiiient
the work of a circuit in watts, by oanaecting
the circuit under test, and Ihn movable ooil
■cult. In thia case, if the voltage current be i,
fiied coil he vi. then the power «1«*1»K^
er. H the inovable coil be not brought back
ted with it be pBrmitTed to move over a grmd-
calibrated dir^tly in watti.
tmeter >> oonaCnicCed eubetsntiilly on this
r (elect ro-dynamometer) mny be reliable for
DOwer, il ia needful thnt <he fine-wire circuit.
QCreAsed by adding auxiliary non-induotiva
CONDEHBERg.
■ Conysalte Eledrlc Balnnc*.
rmploycd to B conniileratile exlent u n etftDdard (c
fafX^wu™' ^tlt h«L9 been almoal enlLrelv guperne-led by Ihe
acliun KDil tepui-
■a Stacdnrci CoropusLte Uslanw.
IningihoHB the tjieory on wliifh tlie "]''''""^?:j^',„ '-i,. „„■ imrlii- a
yriHD foi
_. . _ _ llie riKl.t. Wli.
HCh Wirt
imiUtc<l;«nH, to an taraflP'^''''?*""''' '" n,nife oi"|
pllhi-bcam. leovinif it fr«. ,, ._ r. . .i..in.iminBi
To VtoM ViJlnvlerorCtrUt-amptTrMrlrr. — (A/nBerltueinsttumf<
Ih. circuit or »ur<* of V.M .F throuEi' a non-mJucl.vB «'''' »|"'1 '';f her
inllw tollowira '''»«'■■"; 't' 3"'^* "/"/htZThe'wt^«.ntoi^
_ One o" tlU weinlil- otr,. r UM. •'™. ''. "i»" 'l";^'!"",™* 'n'l'^l.'^hTr; a
44
SYMBOLS, UNITS, INSTRUMENTS.
)
lated by a oompariaon of the scale-reading with the certificate accompanying
the instrument. The volts E.M.F. at the terminals are calculated from the
current flowins and the resistance in circuit, including the non-inductive
resistance used, by Ohm's law, v = IR.
To Uaeaa Hekto-amjiere Meter. — Turn the switch H to ** watts," inisert
the thick wire coils in circuit with the current in such a way that the right-
hand end of the beam rises. Use the " sledge " alone or the weight ma^ed
tD.W,
Terminals E and ^i are then introduced into the circuit, and a measured
current passed through the suspended coils a and h ; and the constants given
in the certificate for the balance used in this way are calculated on the as-
sumption that this current is .26 ampere. Any other current may be used,
say 7 ampere, then the constant becomes 7 •+■ .25 or 4 7.
The current Bowing in the suspended coils g and h may be measured by
the instrument itself, arranged for the measurement of volts. To do this,
first measure the current produced by the applied E.M.F. through the ooiU
VWSAAAAA/ '
SI *'
Fig. 36. Diagram of the Kelvin Composite Balance.
of the instrument and the external resistance, then turn the switch IT to
** watt," and introduce into the circuit a resistance equal to that of the fixed
coils.
To Uae <u a WaUmeter. — Insert the thick wire coils in the main circuit ;
then join one end of the non-inductive resistance B to one terminal of the
fine wire coils, and the other end of /2 to one of the leads ; the other termi-
nal of the fine wire coils is connected to the other lead. The current flowing
and the E.M.F. may now be determined by the methods described above.
The watts can then be calculated from the F^M.F. of the leads, and the
current flowing in the thick wire coils by the formula,
P^=Vr — i IR,
Where i = current in the suspended coil circuit.
7 = current in the thick wire coils.
R = resistance in the circuit.
When working with alternating currents the non-inductive resiiitance R
must be large enouj^h to prevent any difference of phase of the current
flowing in the fine wire coils and the E.M.F. of the circuit.
DOUBLBD SQUARE BOOTS.
46
SMile 9t ]»*«ble« S^vare
r«r liimA KelTte*» Stead-
0
100
200
300 1
400
600
600
700
800
900
O.00O
20.00
28.28
34.64
40.00
44.72
48.99
62.92
66.57
60.00
0
2jOOO
20.10
28.36
34.70
40.06
44.77
49.03
52.96
56.60
60.03
1
2.828
20.20
28.43
34.76
40.10
44.81
49.07
52.99
66.64
60.07
2
3.464
20.30
28.50
34.81
40.16
44.86
49.11
63.03
56.67
60.10
3
4.000
20.40
28J}7
34.87
40.20
44.90
49.15
53.07
66.71
60.13
4
4.472
20.40
28.64
34.93
40.26
44.94
49.19
63.10
66.75
60.17
6
4.880
20.60
28.71
34.99
40.30
44.99
49.23
63.14
56.78
60.20
6
8.292
20.69
28.77
35.04
40.35
46.03
49.27
53.18
66.82
60.23
7
5.867
20.78
28.84
35.10
40.40
45.08
49.32
53.22
56.86
60.27
8
8.000
20J»
28.91
36.16
40.45
45.12
49.36
53.25
66.89
60.30
9
10
6.325
WM
28.98
35.21
40JS0
45.17
49.40
53.29
66.92
60.33
10
u
6.63S
21X7
29.06
85.27
40.56
45.21
49.44
68.33
66.96
60.37
11
12
6.928
21.17
29.12
36.33
40.60
45.25
49.48
63.37
66.99
60.40
12
13
7J11
21.26
29.19
36.38
40.64
45.30
49.52
63.40
67.03
80.43
13
M
7.483
21.36
29.26
36.44
40.69
45.34
49.66
63.44
67.06
60.46
14
15
7.746
21.46
29.33
35.50
40.74
45.38
49.60
53.48
67.10
90JSO
16
IS
8jOOO
21.54
29.39
36.55
40.79
45.43
49.64
53.62
67.13
eoja
16
17
8.346
21.63
29.46
35.61
40.84
46.48
49.68
63.56
67.17
60.56
17
18
8.486
21.73
2dJa
36.67
40.89
45.62
49.72
53.59
67.20
60.60
18
If
8.718
21.82
29.60
35.72
40.94
45.56
49.76
53.63
67.24
60.63
19
%
8.944
21.91
29.68
36.78
40.99
46.61
49.80
63.67
67.27
60.66
20
&
9.166
22.00
29.73
36.83
41.04
45.66
49.84
63.70
57.31
60.70
21
SS
9.381
22.09
29.80
36.89
41.09
45.60
49.88
63.74
67.34
60.73
22
SI
9JW2
22.18
29.87
35.94
41.13
45.74
49.92
63.78
67.38
60.76
23
M
9.798
22.27
£•2
80.06
36.00
41.18
45.78
40.96
63.81
67.41
60.79 ' 24
S
IOjOOO
22.36
•
36.06
41.23
45.83
50.00
63.86
67.46
60..83
60.86
26
18
10.198
22.46
3Oj07
36.11
41.28
45.87
50.04
53.89
57.48
28
27
10.392
22M
30.13
36.17
41.33
45.91
50.06
53.93
57.62
60.89
27
28
10583
22.83
30.20
36.22
41.38
46.06
60.12
53.96
67.65
60.93
28
28
10.770
22.72
30.27
36.28
41.42
46.00
60.16
64.00
57.58
60.96, 29
88
10.964
22.80
30.33
36.33
41.47
46.04
50.20
64.04
67.62
eoM
30
«
11.136
22.89
30.40
36.39
41.52
46.09
50.24
64.07
67.66
61.02
31
82
11.314
22.98
30.46
36.44
41.57
46.13
60.28
64.11
57.69
61.06
32
3S
11.489
23.07
30.53
36.60
41.62
46.17
50.32
54.15
57.72
61.00
33
81
11.602
23.15
30.50
86Ji6
41.67
46.22
5036
64.18
67.76
61.12
34
m
11.832
23.34
30.66
36.61
41.71
46.26
50.40
54.22
57.79
61.16
36
38
120)00
23.32
30.72
36.06
41.76
46.30
50.44
54.26
57.83
61.19
38
37
12.166
23.41
30.79
36.72
41.81
46.35
60.48
54.30
57.88
61.22
37
88
12.329
23.49
30.85
36.77
41.86
46.38
50.52
54.33
57.90
61.25
38
98
12L480
23.58
30.92
36.82
41.90
46.43
60.56
64.37
57.93
61.29
39
48
12.849
23.66
30.98
36.88
41.06
46.48
60.60
64.41
57.97
61.38
40
41
12.808
23.75
31.06
36.93
42.00
46.62
60.64
54.44
58.00
61.35
41
42
12.961
23.83
31.11
36.99
42.06
46.56
fiO.68
54.48
58.03
61.38
42
a
13.115
23.92
31.18
37.04
42.10
46.60
60.71
54.62
58.07
61.42
43
44
13.268
24.00
31.34
37.00
42.14
46.65
60.76
64.55
58.10
61.45
44
4B
13.416
24j08
31.30
37.15
42.19
46.69
60.79
54.69
58.14
61.48
46
48
13^665
24.17
31.37
37.20
42.24
46.73
60.83
64.63
58.17
61.51
46
47
13.711
24.25
31.43
37.26
42.28
46.78
60.87
54.66
68.21
61.55
47
48
13.868
24.33
31.50
37.31
42.33
46.82
50.91
64.70
68.24
61.68
48
48
14M00
24.41
31.56
37.36
42.38
46.86
60.95
64.74
58.28
61.61
49
68
14.148
24.49
81.62
37.42
42.43
46.90
50.99 r>4.77
58.31
61.64
60
46
8TMB0L8, UNITS, INSTBUMEKTS.
0
100
200
300
400
500
600
700
800
900
51
14,283
24.58
31.69
37.47
42.47
46.95
51.03
64.81
68.34
61.68
61
52
14.422
24.66
31.75
37.52
42.52
46.99
51.07
64.85
68.38
61.71
62
53
14.560
24.U
31.81
37.58
42.57
47.03
51.11
64.88
68.41
61.74
63
54
14.697
1M.82
31.87
37.63
42.61
47.07
51.16
64.92
68.45
61.77
64
55
14.832
24.90
31.94
37.68
42.66
47.12
51.19
64.95
68.48
61.81
66
56
1 14.967
24.98
32.00
37.74
42.71
47.16
51.22
54.99
68.51
61.84
56
57
15.100
25.06
32.06
37.79
42.76
47.20
51.26
55.03
68.55
61.87
67
58
15.232
25.14
32.12
37.84
42.80
47.24
51.30
55.06
58.58
61.90
58
59
15.362
25.22
32.19
37.89
42.85
47.29
51.34
65.10
68.62
61.94
69
60
15.492
25.30
32.25
37.95
42.90
47.33
61.38
65.14
68.65
61.97
60
61
15.620
25.38
32.31
38.00
42.94
47.37
51.42
65.17
68.69
62.00
61
62
15.748
25.46
32.37
38.05
42.99
47.41
51.46
65.21
68.72
62.03
62
63
15.875
25.58
32.43
38.11
43.03
47.46
51.50
56.!U
58.75
62.06
63
64
16.000
25.61
32.50
38.16
43.08
47.50
51.54
66.28
58.79
62.10
64
65
16.125
25.69
32.56
38.21
43.13
47.54
51.58
66.32
68.82
62.13
66
66
16.248
25.77
32.62
38.26
43.17
47.68
51.61
65.35
68.86
62.16
66
67
16.371
25.85
32.68
38.31
43.22
47.62
61.65
65.38
68.89
62.19
e7
68
16.492
25^
32.74
38.37
43.27
47.G7
51.69
65.43
68.92
62.23
68
69
16.613
26.00
32.80
38.42
43.31
47.71
51.73
65.46
68.96
62.26
69
70
16.733
26.08
32.86
38.47
43.36
47.75
61.77
66.60
68.99
62.29
70
71
16^2
26.15
32.92
38.52
43.41
47.79
61.81
65 J»
69.03
62.32
71
72
16.971
26.23
32.98
38.57
43.45
47.83
61.85
65.67
69.06
62.35
72
73
17.088
26.31
33.05
38.63
43.60
47.87
51.88
56.61
69,09
62.39
73
74
17.205
26.38
33.11
38.68
43.54
47.92
61.92
65.64
60.13
62.42
74
75
17.321
26.46
33.17
38.73
43.59
47.96
51.96
66.68
69.16
62.46
76
76
17.4;J6
26.53
33.23
38.78
43.63
48.00
62.00
65.71
69.19
62.48
76
77
17.550
26.61
33.29
38.83
43.68
48M
62.04
66.76
59.23
62.61
77
78-
17.664
26.68
33.35
38.88
43.73
48.08
52.08
65.79-
69.26
62.55
78
79
17.776
26.76
33.41
38.94
43.77
48.12
52.12
65.82
59.30
62.58 79
80
17.889
26.83
33.47
38.99
43.82
48.17
62.15
65.86
59.%
62.61
80
81
18.000
26.91
33.63
39.04
43.86
48.21
62.19
65.89
69.36
62.64
81
82
18.111
26.98
33.59
39.09
43.91
48.25
62.23
66.93
69.40
62.67
82
83
18.221
27.06
33.65
39.14
43.95
48.29
52.27
66.96
59.43
62.71
8»
M
18.330
27.13
33.70
39.19
44.00
48.3:1
52.31
66.00
69.46
62.74
84
85
18.439
27.20
33.76
39.24
44.05
48.37
52.36
66.(H
59.50
62.77
85
86
18.547
27.28
33.82
39.29
44.09
48.41
62..38
66 07
59.53
62.80
86
87
1S.&55
27.35
33.88
3Q.M
44.14
48.46
62.42
66.11
69.57
62.83
87
88
18.702
27.42
33.94
39.40
44.18
48.50
62.46
66.14
59.60
62.86
88
80
18.868
27.50
34.00
39.45
44.23
48.54
52.50
56.18
59.63
62.90
89
90
18.974
27.57
34.06
39.50
44.27
48.58
52.54
66.21
69.67
62.93
90
91
19.079
27.64
34.12
39.55
44.32
48.62
62.57
56.26
69.70
62.96
91
92
19.183
27.71
34.18
39.60
44.36
48.66
62.61
66.28
69.73
62.99
92
93
19.287
27.78
34.2,J
39.65
44.41
48.70
52.65
66.32
59.77
63.02
93
94
19.391
27.86
34.29
30.70
44.43
48.74
52.G9
66.36
59.80
63.06
94
95
19.494
27.93 34.;«
30.75
44.50
48.79
52.73
50.39
59.83
63.09
95
96
19.500
28.00
34.41
39.80
44.54
48.83
52.76
56.43
69.87
63.12
96
97
19.698
28.07
34.47
30.85
44.59
4S.87
52.80
56.46
59.90
63.15
97
98
19.799
28.14
34.53
39.1K)
44.rt3
48.91
52.84
56.50
59.93
63.18
98
99
19.900
28.21
34.58
39.95
44.68
48.95
52.88
56.53
59.97
63.21
99
100
20.000
28.28
34.64
40.00
44.72
48.99
62.92 50.67
60.00
63.25
100
THE POTENTIOMETER. 47
In its simplest form the potentiometer may be represented by the dia-
gnm. Fig. 37.
A B la & resistance in which a constant current from the battery IF is
znalntained. The regulating resistance R is used to compensate for varia-
tions in the E.M.F. or internal resistance of the battery W. The con-
stancy of the current in yl B is checked by seeing that the drop in poten-
tial between two points chosen in it is equal to tne E.M.F. of a standard
oelL The standard cell is introduced into the circuit M. E. M.' tit E^ and
the regulating resistance R adjusted until the sensitive galvanometer O
shows no deflection. Assuming A B to have a uniform resistance through-
out its length, and the current in it to remain constant, it is obvious that
any other voltage not greater than the drop between A and B can be
measured by introducing it at E and shifting the points MM' until the
gahrmnometer again comes to a balance. Further, a direct reading scale
may be placed between A and B, For
most potentiometer work the drop i iL
between A and B is made about 1.5 | A
volts, as this is about the E.M.F. of a/a/vw^aaaa/v ^
a standard Clark cell. That the instru- | m " VT
ment may have a wide range and ■" ^
B
ment may have a wide range and '^ +
make measurements to a sufficiently p /^^^
high degree of accuracy, it is neces- 1— o o ( t V- — '
sary that it be possible to sub-divide V_>^
this resistance, so as to read voltage -r. 07
to at least the fifth decimal place. '*"• ^'•
Since the current must be kept constant the total resistance in the circuit
must not be varied by raising the resistance between M and M\
SaaC** — To meet general laboratory requirements the potentiometer
must measure directly as high as 1.5 volts so that all kinds of standard
cells may be compared with each other; and it must measure as low as
.00001 volt so that reasonably )ow_ resistance standards may be used in
measuring current. An example will make this point clear. To measure
1000 amperes the current must flow through a standard low resistance
and the drop in E.M.F. across its terminals be measured on the potentiom-
eter. With a potentiometer reading only to .0001 volt the drop across
the low resistance must be at least .1 volt in order that it may be read to
an accuracy of ^%. If 1000 amperes is the maximum current to be used
on the particular low resistance it should be so designed as to give proper
readings with a minimum current at least as low as 100 amperes. 100
amperes must consequently give a drop of .1 volt, which fixes the resistanceat
Ml ohm. .001 ohm to carr^ 1000 amperes must be able to dissipate 1000
watts, and in order to remam a standard it must do this without heating
enough to vary the resistance outside of small limits. With a potentiometer
reading to .00001 volt the same range of current can be handled on a resist-
ance of .0001 ohm and can be measured to the same degree of accuracy.
To carry 1000 amperes it will only have to dissii>ate 100 watts. To maintam
the same degree of accuracy while a current is flowing it can consequently
be made of a very much smaller size and with -t^^he radiating surface.
Methods of VJslnir tli« Standard Cell. — The standard cell is
used to measure the current flowing through the potentiometer, which is
done by making the drop in E.M.F. across a known resistance in the circuit
equal to that of the standard cell.
Ist Method. — The standard cell maybe used as indicated in Fig. 38.
The gialvanometer is permanentiv in circuit with the points 3/ A/', and by
meanii of the double-throw switch U the standard cell *S', or an unknown
E.M.F. Et may be thrown into the same circuit. If the resistance A B is
Sovided with a scale by means of which it is sub-divided into, for example,
,000 equal parts, the points MM* may be set to a reading corresponding
to the E.M.F. of the standard cell and the current from the battery
W reipilated by the resistance R until there is a balance, the standard cell
beins in circuit with the galvanometer and points MM'. There will then
be such a current flowing that for any other position of the points MM',
producing a balance with the unknown E.M.F. in circuit, the reading from
the scale will be direct in volts. This method is open to the objection that
it requires a resetting of the points MM' to make a check measurement
of the current flowing. In making accurate measurements these check
48
SYMBOLS, UNITS, INSTRUMENTS.
moamirementfl have to be made frequently and are especially inconvenieat
by this method when the points Mm* are multiplied from two to four or
five as they generally are.
2d Method. — A meihod of measuring and checking the currents whidi
avoids this objection is shown in Fig. 39. It is not necessary that the re-
sistance which furnishes the drop, against which the E.M.F. of the standard
i^ M^iB ijHAlv «
Fxo. 38.
Fio. 39.
eell is balanced, be between the points A B, which limit the motion of MM'.
If placed at lU and proi>erly cnosen with reference to the E.M.F. of the
standard cell and the resistance of the wire A B, the current which pro-
duces a drop across it equal to the E.M.F. of the standard cell will make
the scale of A B direct reading in volts. In this case the double-throw
switch is arranged so as to thvow the galvanometer eithor into the circuit
containing the standard cell and the resistance R*, or into the circuit con-
taining the points MM' and the imknown E.M.F. This method is, how-
ever, open to a serious objection from the standpoint of accuracy, which
is avoided by the first. To illustrate this by a numerical example, assume
in both cases all the resistances adjusted to an accuracy of ^ of 1% and
the error to be in such a direction as to produce the worst result. In the
second method if the resistance R* were ^% high the current flowing
through the potentiometer would be A% lower than it should be. If now
the resistances of A B were i^% low this
would introduce a second error of the
same amount in the same direction
and the resulting error in measurement
would be A%> Iq other words the
measurement accuracy throughout the
range of the potentiometer may be
only half so good as the adjustment
accuracy. In the first method, since
the standard cell E.M.F. and the un-
known E.M.F. are balanced against
the drop across the same resistances
in meastuing an E.M.F. nearly equal
to that of the standard cell, inaccura-
cies in the resistance are the same in
both cases and balance each other,
measurements are bound to be more
In a potentiometer
Fio. 40.
Consequently by this method measurements are
accurate than the adjustment of the resistances.
arranged to be used with a Clark cell using the first method of applying
the standard cell and with resistances adjusted to A% it can be shown by-
calculation that the maximum error in measurement will vary with the
value of the E.M.F. under measurement. For E.M.F. of 1.5 volts this
crrorwill be less than .003%. For E.M.F. of 1.2 volts it will be about .01%.
For E.M.F. of .8 volts it will be about .02%. For E.M.F. of .3 to .1 volts
It will be .04%, and in no case will be larger than this. To sum up the con-
trast in accuracy between the two methods: in the second the errors may
be twice as great as the adjustment errors throughout the range, while in
the first method they only become this larae for .3 volt and under, and for
higher voltages have increasing accuracy becoming equal to that of the
adjustment at .8 volts and much better as they approach the E.M.F. of
the standard cell; at exactly the E.M.F. of the standard cell the accuracy
of comparison becomes independent of the accuracy of adjustment of the
resistance.
DST1ESMINATION OF WAVE FORM.
49
ad Method. -—A third method combines with the aoouracy of the firet. the
JS!lS!!KSi'*'. l^ *25**- ?*"'»»f"»t«tedinFig.40. Tli E.M.F. b? tS
stABdani edl u balanMd against the drop across a part of the potentiometer
wire ii/^ asm method No. 1, but the termmals of this resistance are found, not
^* k R*??^ ^ W' ****.* *^*y *" permanently fixed, and the double-
♦wlf— ^!^*;iX" /VTiT TL* "V "**'*'' "^"" Kj»*u»««?uwjr IM.I3U. fuia cne aouoie-
tArra- switch U throws the galvanometer mto one circuit or the other as de-
AA TtMllNALS
OJT WAITS FORM or cimiftMirv
KliBCXliOMOTKVJB f OJROM.
TBSBS are numerouB methods of determining ware form, those used in
uboratm experiments commonly making use of the ballistic galranometer.
Of the siinple methods used in shop practice, R. D. Mershonrof the West-
*W?^?®***'^^*?*l^*°^*®**^"K ^'* *>»■ applied the telephone to an
Old DalUatIc method in such a manner as to make it quite accurate and
readily u^plied.
McnteB'a Method.— The following cut shows the conneoUons. A
telephone receirer, shunted with a condenser, is connected in the line from
the Bonrce of current, the wave form of which it is wished to determine. A
eoatact-^iaker is placed in the other leg, and an external source of steady
earrent, as from a storage battery, is opposed to the alternating current, tm
shovB. The pre^ure of the external current is then varied until there is
BO sound in the telephone, when the
pcesnres are equal and can be read
from the voltmeter. The contact-
maker being revolved by successive
itMs, pointB may be determined for an
oittre cycle. ^^
•■McauB'a H«tb9d. — Where it
ii desirable to make simultaneous de-
teradnatioiis it will ordinarily require
several contact-makers, as well as full
sets of instruments. Dr. Louis Dun-
can baa devised a method by which one
eoolact-maker In connection with a
dvnamometer for each curve will ena-
Ne all readings to be taken at once.
The following cut shows the connec-
tkine. The nxed coils of all the dy-
aamcnneterB are connected to their
reqieetive circuits, and the fine wire
iMvablecoila of atwut 1,000 ohms each,
are connected in series with a contact
■laker and small storage battery. The contact-maker is made to revolve in
■yacbronism with the tutemating current source. Now, If alternating cur-
nuts frcwk tbe different sources are passed through the fixed coils, and at
intervals of the same frequency current from
the battery is passed through the movable coils,
the deflection or impulse will be in proportion
to the instantaneous value of the currents
flowing in the fixed coils, and the deflections of
the movable coils will take permanent position
indicating that value, if the contact-maker and
sources <n alternating current are revolved in
unison.
The dynamometers are calibrated first by
passine continuous currents of known value
through the fixed coils, while the regular in-
terrupted current from the battery is behig
passed through the movable coils.
JRym'a Jtetliod.— Prof. Harris J. Ryan,
of Cornell university, designed a special elec-
trometer for use in connection with a very fine
series of transformer tests. This instrument
. ^ ^ . . ^^1 ^ found described and illustrated in the
chapter on desoriptioii of instruments.
Fio. 41. Mershdn's method of d^
termining Wave Form.
Fio. 42. Duncan's method
of determining curves
of several circuits at the
time.
60
STUB0I.8, UXIT8, IXSTRUHEITTS.
• ■w«n«rtmMftn
The method of using it is shown in the cut below, in which the contact-
maker shown is made to revolve in a^'nchroniam with the source of alter*
nating current. The terminals, d di, of the indicating instruments can be
connected to any one of the three sets of terminals, o Oi, 6 &i, e C|.
The terminals, a ai, are for readinjg
the instantaneous value of the pri-
mary impressed E.M.F.; b 6|, the
same value of the current flowing
through the small non-inductive re-
sistance, R\ and c Ci the same value
of the secondary impressed E.M.F.;
the secondary current being read
from the ammeter shown. Of course
if the contact -maker be cut out, then
all the above values will be 's/meau^*
nTTTTTTT
A.C.AMICTtK
Rosa Carre Tracer.
IVAN ILECTMHCTU
Fio. 43. Prof. Ryan's Method of
obtaining Curves of Wave Form
for studying Transformers.
This instrument consists of a hard-
rubber cylinder upon which is wound
a single layer of bare wire. A con-
stant current from a small storage
battery is sent through this coil causing a uniform drop of potential be-
tween its ends. (See Diagram, Fig. 44.) A voltmeter connected between
the terminals indicates the drop, and the resirttance R in series with the
battery serves to regulate this drop. The current to be plotted passes
through the non-inductive resistance A B and the problem is to meajnure
the instantaneous values of the drop between these two points at succes-
sive instants throughout the perioii of a wave. The point B is joined to
the middle point Q of the spiral wire ^fN,
A is joined through the revolving contact'^
maker C M to a sliding contact P.
The contact-maker is joined to the
shaft of the alternator, or is at least
driven in synchronism with it; then
every time tne contact is completed at
any pmrticular phase of the wave, the
current has the same value and the gal-
vanometer will show a deflection. If
the sliding contact P be adjusted so that
the galvanometer shows no deflection,
then the potential diff'erence between the
points P and Q is the same as that
between the points A ami B. Tliis value
is proportional to the distance P Q, and
is positive on one side and n^ativo on the other side of Q.
For making the record, a cylinder is arrangc<l opposite the potentiom-
eter wire and slider, upon which the paper for the record is wound. A
tripping point is attached to the slider in such manner that when the gal-
vanometer has been brought to zero by the adjustment of the resistance /?.
the pointer is tripped and a point impre^scxl on the record paper through
a typewriter ril)lD<m, and at the same time the record cvlinder is advanced
a notch or series of them as may he renuirwi, ready for the next record.
By this means the plotting of a curve of current or potential takes but a
few seoomls.
OMcillocrapli- — Tljis form of instrument devised byBlondel and others
is much used for the analysis of wave forms of current and electromotive
force, and for the study of potentials anfl other properties of alternators
or other forma of dynamos and motors. It is extremtly sensitive and will
detect and show either on a screen or a photograph, the most minute varia-
tions in current and potential. Tlie Blondrl t>'pc described below will
serve to show all the principles of the instrument- Durlell has somewhat
improverl upon this one. anrl the Grnrral Electric Co, has designed another
that is especially adapted to workshop practice.
Fio. 44. Rosa Curve Traoer.
DBTEKHIKATION OF WAVE FORM.
ThengrsTini; (Fif. 46)shoi>a tbe Mtieral Kppeaninn of the OKtllognph.
Thaappuatiu IS mounted in a box (Pig. 4a)wjth an ani lamp at ona tnd.
Abore a a crouDd-slaBa screen upon which the wftve Fonns are ti^ced by
Tia. 46. Blondel Osoillograph,
■ ipol of light. The magrnal ^
the poles are placed two aimil
inm bridaa-piece which rende
mounlsd on the left in an iaveited jsoaitioD
made up o( six horaeahoe pieces. Betweei
,r aetH of vibratioR bands, separated by ai
s ewh one im iudependent uikil. in thi
>
BTUBOLSj UHITB,
UrSTBUHENTS.
ud eumot. knd ■» leen on ta
Ths HTftngeDHat of moUDliiii
fine and nturow itiip of soft in
nnd one five-bundrcdlh of an
LM, Bucb HI (Jib eleotR>nu>tiT« fOTM
in Iheir rdativa ru— irir^n-
seeoin.Fig.47; t
LS band ia a "nry
i ibiek. fiiis l»nd ie heJd in a mov-
abla BUppon in a verticsJ position be-
tween the polen of Lh« taAgnet, It
ftt a to a Blidlng piece which ma
■ reotansular groove. The slidi
rice a rod n above, which paaaec
■o that by turmo
ia atrelohed more
bridcCB. The b»
ntainsl in a tubL
of Ivory, which Gta into |
the nudnet poln and a
about Sy the collar D.
D the
a a small
~he mirror
oil boi T
be turned
nucn ett-ve to coneentraie the field;
tt £ ia a lene placed in front of tbe
□itror. In tins way the aoft iron
Hece vibratee without the use of piv-
>tg or suBpension. Each horiiontal
na^net, and the deflections produced
}y the Doib socumulale from the ex-
^remitiea to the ceutv of the baud.
ddenbly. The toUl deflecliona in-
iicated by the mirixir are propor-
JODsl to tbe current. Owing (o the
)ropertiefl peculiar to vibrating bands
Blondel O^lo^aph, ^hL"^ "fifnhwTZLSi ty^'ib? ES^-
poution in the inacnetio fidd. Where
it be affected by
, and the higher t'
n Fig. 4S.
"tw^'dHarei
ncillographs which a
j«. Atlw ia an tuiJuBtsble i
form the beae line of the c
g the vibrating banr). a per
tlone. which will answer in moat ou
irrwilar. The wmsitivEncm in the
of the spot of light of 100 millimeM
e the pole-piecea. built of
the atrip. Th«e are two
lotion in (he center, tbiu
quite independent of aach
ray. The oil tube T oon-
. On the left is geea™e
:ical opening Co allow '
15.000 T^""
cave fot
— sacoDd
o the band.
20.000 viim.
ia geoflrally brought U
Ibkl the band haa ai
DBTKRMI.VATIOM OF WAVE FORM.
Ok band it nol yM iBtunud. than d«(ir«u« when ihe muneiiulJ
. . ■ ._, rapidly tbmn the fidd Mrmglh. Tlie numl
^ [»pidly at first, then iloirly, u I
1
i
fn. 18. Blondel OMiUasrkph, ahowing the Amncemant ol the Macnet.
itrip. lltey hava dow bwD nduoed a
0.5 mUliowtcr bixh, ^th a thiclcoflaB of but u.uo to u.i mijiimQcer. Diirer«a
•ha or mica ia ussd, aod ths miironi are fastened to Hie bands with BbelJao
Btfcn the toiler are mourned. Aa the baad i> enclowd in so oil box it
■ tm from mat and wall protected. The eensilivenna dF the initniment
j mj be creatly varied by usinB an iron yoke which is placed against the
iltiie firld at the poln.
. To U» lisbl of Ihe bol irill b« seen the arrangement of the oscillating
I wrar rnbiA Dvea Che (o4iHi-fro motion to tha HWt o( light in order to
I fccni the wmTB. The device will be understc-^ ■-- ■'■--'^ — -- ^■■' ■"
Stta arc lamp whieh throws a beam of light
' iiBtter F upon the mirror of the oscillograph i
'ud tmmtt throuih the lios /. falling on the OKiiiBiitv mirror m |
I Hbind it. The latter i* given s to-and-fro motion by a small synchi
~" ' m of light thus far has two movemenW, one by the i
• oi the oeeillocniph and the other by Ihe
. ibf two giv«0 the wave form which b ]
ited above on iba ground-glaai
1
54
SYMBOLS, UNITS, IXSTKUMENTS.
BcreOD P. The to-and-fro movement of the mirror is obtaiaed by a cam
fixed to the motor-shaft. During two complete periods of the wave the
"t
Fio. 49. Diagram showing the Arrangement of the Apparatus in the
Blondel Oscillograph.
mirror must be moved at a continuous rate from top to bottom, and during
the next period it must be able to return so as to continue the movement
(as will be noticed on the photograph two
complete waves are throvoi on the screen).
This is carried out by the profile of the
cam which is such that the mirror has a
uniform movement during two cycles of the
wave, and the next cycle is occupied by the
return of the mirror (during this time an
electrically operated shutter placed at F cuts
off the light), so that the eye perceives only
a continuous trace of the wave. To observe
phenomena which are not periodic the motor is replaced by a pendulum
device.
Fid. 60.
r
MEASUREMENTS.
Rbvued bt W. N. Goodwin, Jr., axd Pbof. Sam ukl Shbldoit.
is the fundameDtal law of electrical ciroiiita and is ezprened t
ID the following equations.
R
E = IR
«=?
where / = Current strength in amperes,
R ^ Resistance in ohms,
E = Electromotive Force in volts.
The oonductance of a conductor is the reciprocal of its resistance, and
tltt unit is called a mAo, so that Ohm's law may be stated as follows:
I=BO
where O = conductance in mhoa.
Maltlpl« Gii«aMa. — The oonductance of any number of circuits in
psimDd is equal to the sum of the conductances of the individual drouits.
which is, as stated abore, the reciprocal of their resistanoes. The combined
raastanee then is the reciprocal of the conductance thus found.
Thus in Fi^. 1, if r and ri be two resistances in
pscsllel, the oombLned renstance = ^ 1 = , ^ «
1 , J. r-\-n
r n
The joint reodstanoe of any number of resistanoes
in parallel as a, b, c, and d is
1_l1_i_1_i_1_i_ *
a+6 + c+d + **^
C«rreBt Im m MslMple CIrcatt is divided Fio. 1.
unoQg the separate circuits in direct proportion to
respective conductances, or inversely as their resistances.
In Fig. 2, the total resistance of circuit
£"=
'v total current
r-i-n
j^ J?(r + r,)
and i =:
En
Rr + Rri+ m
%t =
Er
Rr -t- Rri + m
Fio. 2.
Rr + Rn + m
a^v» AiK
Vfrat litter. — If in any circuit a number of currents meet at a point,
the sum of those flowing toward that point is equal to the sum of those
flowing away from it.
Sc^m4 MtAir. — In any closed circuit, the algebraic
mm of the products formed by multiplying the re-
^i»ri^
VWiV^AW^AAAX
SMtanoe of eaeh part by the current passing through
it is equal to the sum of the electromotive forces m
the dreait.
By means of these laws, the current in any part of
sa intricate system of conductors can be founa if the
resistanoes of the different parts and the electromotive
iorees are fliyen. I
Thus in Fig. 8, according to the first law i = t| + ia — 1
aad from the second law t={i ^ is and from the secona
law E^uTi and iitt =iiri. Fio. 8.
From these three formuls, the three unknown currents can be dedused
Toe sanae method can be applied to more complex drouits.
5fi
56
MEASUREMENTS.
RSAUTAirCB MMAMMJMMMMM'Em.
Metli«d* — This is the nrnplcet method of measorinc
resietanee. The resistaaoe to be measured is inserted in aeries with a
Sulvanometer and some constant source of current, and the ^Ivanomeier
eflection noted; then a known adjustable resistance is substituted for tiie
9 unknown and adjusted until the same deflection is acain obtained. Then
this value of the adjustable resistance is equal to that of the resistanoe
to be measured.
IHIVeremtiAl CtAlvAaometcir Metltod. — In galvanometers ha vine
two coils wound side by side, separate currents sent through them in opposite
directions exert a differential action on the movable system. In a differ-
ential galvanometer the two coils are equal in their magnetic action on
the movable system for equal currents, so that equal currents sent through
them in opposite directions will not deflect the needle. If the currents
' are unequal, then the deflection is a measure of their difference. Thia
form of galvanometer may be used to measure resistanoe by inserting the
unknown resistance in circuit with one coil of the galvanometer and a
known adjustable resistanoe with the other, both circuits beins connected
in multiple. Then when the resistanoe is adjusted imtil no deflection is
produoea the resistances in the two circuits are equal.
The method is often used in the comparison of the conductivity of wire,
and where rapid measurements not requiring great accuracy are desired.
W^lieatet4ni«*a JBrMfpe. — For accurate measurements of resistance
the Wheatstone Bridge method is almost universaU:^^ used; Fig. 4 is a dia-
gram of the connections in which a, 6, and R are
known resistances and x the unknown resis-
tance to be measured. O is the galvanometer,
and fi is a battery of several cells, the number
.4 of which may be varied according to the value
of the resistance x. R is adjustM until there
is no deflection of the galvanometer needle when
both keys are dosed.
The battery key should always be closed be-
fore the galvanometer key is depressed or there
will be a ^' kick " in the galvanometer due to the
sdf inductance or capacity of the circuit under
test.
FiQ. 4.
X h h
When a balance is established - =-, or x = R -•
. Ran
Tlie resistances a and b are, in practice, made even multiples of 10, so
that X can be read directly from R, the proper number of figures b^ni;
pointed off decimally.
If a = 6 the value of z is the same bb R, If x be sreater than the ca>
pacity of R, or low in comparison to it, then a and 6 must be so chosen
that their ratio respectively multiplies or divides R,
For example, let
6=1000 {then x = ". ft=^-^X 243 = 24,300.
« = 243 ) «
10
The ratio of a to 6 being 100, any reading as ft is multiplied by 100, or
again let
a =1000
6=10
« = 243
then X =
10
1000
X 243 - 2.43.
The ratio of a to 6 being r^. any reading as R should be divided by 100.
A commercial form of Wheatstone Bridge of the Weston Model is shown
diaKrammatically in Fig. 5. This type, called the "plug in" type, or some
modification of it, is most commonly used. It has tne advantage over the
'* plug out " type in that fewer plugs are required, there being but one
plug needed for each decade; this reduces the plug error to a minimum.
BESISTANCE HBASUBEMEKTS.
67
igr OlHMHieter. — Another form of instrument used
for mtmmannf resistances is known as the direct reading ohmmeter. Briefly
described it is simply a slide wire bridp^e. the wire formins two of the arms
of the bridce. a known resistance a third arm, and the unknown resistanee
rH(i[iH
^ B« 6- C13:
HUNOS. TEMS UNITS R X
c— — X — ^l..,l^. —
T-_,I j-
-SBa
1 -P Qa P
I X I
1-^-i
Fia. 6.
tiie fourth. The shde wire is graduated to read directly in ohms, and is
printed with niunbers in black and red. The black numbers refer to a bw
reading scale which is used when the single plug of the instrument is fitted
into tbe hole marked black, and the red numbers refer to a higher scale
Fio.6.
♦HI
Fio.7.
F%. 6 shows diagrammatically the oonneetions of this Ohmmeter, and Fig. 7
gives Uie same ones expanded into the conventional Bridge Form.
the plug is inserted in the hole marked red. This instrument usually
kss four scales, although it is sometimes made with three and five. The
Aie wire is doubled back on itself by means of a heavy cross block of
practically sero resistance.
The detector circuit comprises a detecting instrument ordinarily a tele-
% and a stylus, which is touched at various points along the
68
MEASUREMENTS.
slide wire until the detector by silence indicates a balance, when the resoit
is read directly in ohms. In some of the instruments the battery is equipped
with a small induction coil which provides alternating current. In this
form the instrument is useful for meiisuring electrolytic resistance and
other resistances containing electromotive forces that may be developed
by the presence of current therein, and by the use of a suitable condenser
in place of the known resistance, capacities can be compared.
virectloBUi for Use of liar« Direct RoiMtUiir Oliii«ot«>r. —
To Measure Resietance. Connect the terminals of the circuit to be measured
to the posts, A and D. Place the telephone receiver to the ear and cloee
the battery key, K, located in the receiver. Hold the stylus, <S, in the
hand in the same manner as a pencil, and with it touch the straight wires
along their entire length until a point is readied where gentW tapping the
stylus on the wire produces no sound in the telephone. The resistance
sought is then that indicated by the scale under that point of the wire.
Dunng these readings the plug, P, must be in one of the sockets at the
right-hand end of the rubber cross-bar. When in the socket marked "red"
the scale numerals printed in red should be used. When in the socket
marked "blue" the blue numbers should be read, etc.
Slide-wire Sridflr** — A very convenient form of bridge for ordinary
use where extreme accuracy is not de-
manded is the slide-wire bridge, shown in
Fig. 8. It consists of a wire 1 meter long
and about 1.5 mm. diameter stretched
parallel with a meter scale divided into
millimeters. A contact key is so arranged
.as to be moved along the wire ao that
contact with it can be made at any
point.
A known resistance R is connected as
shown; x is the unknow^n re8i8ta.nce; the
PiQ. 3, galvanometer and the battery are con-
nected as shown in the figure; atter closing
the key Art the contact 3 is then moved
along the wire until the galvanometer needle returns to zero;
then again;
and
a : b :: R i x^
bR
x =
a
The C»rey-Foater IVIetbod. — For the very precise comparison of
nearly equal resiKtances of from 1 to 100 uhms this method yields exquisite
results. In Fig. 9, Si an<l .S'2 represent the two
nearly equal resistances to be compared, and Ri,
R2 represent nearly equal rei^istances, which, for
best results, shouUl not differ much in magnitude
from iS, and S2. *^i and ^^2 s^^e connected by a
slide wire whose resistance per unit length p is
known. The battery and galvanometer are con-
nected as in the diagram. A balance is obtained
by moving the contact c along the stretchecl wire.
Suppose the length of tlie wire on the left-hand
side to the point of contact to be a units. Then
exchange iSi ami S^ for each other without alter-
ing any other connections in the circuit. Vpon
producing a new balance, let oj be the length of
wire to the left of the contact.
Fio. 9. Carey-Foster
Bridge.
Then
Siz=St+{a-aOp.
. Special commutators are upon the market which have for their purpose
the easy exchange of /?» and *S2.
To avoid thermal effects, wliich arc nuite considerable with resistances
made of some materials, the battery sliould be commutated for each pC'sition
of the resistances to be compared. The readings for the two balances ac-
companying the battery commutation shouUl l>e averaged.
BESISTANCE MEASUREMENTS.
69
3K9mmur9m^0tmtm of JLow ]i«»Uitamce««
KelTla's ]»o«ble
Bridge* — If a Wheatotone
bridge be used to compare re-
sistanoeB hftving a value much
lesB than one ohm, the terminal
and eontact resistances produce
a considerable error in the re-
sults. In conductorB having
such low resist ance, the value
of the resistajioe pven or to
be measured is considered as ly-
ing between two definite points.
In standard resistances these
points are connected to twoter-
Fia. 10. Kelvin's Double Bridge.
Biinals called potoitial terminals. ^ .,^ ... . «_. i_ ^.
Kelvin has designed a modified form of Wheatstone bndge m which the
above-mentioned errors are eliminated. The method is shown dii«rammati-
cally in Fig. 10, in which R and x, the resistances to be compared, he between
5 and Si on one and between T and Ti of the other, and are connected
together at y; n and o are auxiliary resistances also adjustable. A galva-
oometer is connected through a key, as shown, to two pomto. one at the
junction of nand o; the other at the junction of a and o. If n and o be
so adjusted that n:o::R:x, and a and b be adjusted so that the galvano-
meter is balanced, then
a :h : : R : x.
or
« =
hR
In practice, n and o may be changed during the adjustment of a and 6
so as to maintain the ratio of n to o the same as that of a to 6, cither by
ehanjqng n and o, on standard rheostats, or by opening the circuit at y
sod adjusting n and o. as in a regular bridge, for a balanc^ after each trial
value of a and b; then when a balance is obtained in the galvanometer
with circuit at y both open and closed the above equation holds good.
Amotiier Metliocl War Compfarlaon oflow JR«al«tances. —
For comparing the resistances of ammeter shunts, etc., with standard side
terminal resistances of the Reichsanstalt
foam, the method of Sheldon yields
rery accurate results. The unknown
rodstance z. Fig. 11, which may be a»-
ramed to be supplied with branch po-
tential points a o, is connected bv heavy
coodoctors in series with a standard re-
sistance R, having potential points c d.
From the two free terminals T T^ of
these resistances are shunted two 10,000
ohm resistance boxes S P, adjusted to
the same normal temperature, and
voond with wire of the same or negli-
gable temperature coefficient, and con-
nected in series. From the point of
connection c, between the two boxes, connection is made to one terminal uf
the galvanometer g, the other termhial being coimected successively with
the potential points a, b, c, and d. At the outset all the plugs are removed
from the box Sj and all are in place in the box P. After connecthig T and
r» with a source of heavy current, plugs are transferred from one box to the
eorresponding holes in the other box (this keeps the total resistance in the
two boxes constant) until no deflection is observed in the galvanometer.
This (Moeration is repeated for each of the potential points a, 6, c, and d. Bep-
rsientlng the resistances in the box S on the occasion of each of these bal-
ances by 5«, Sh, 5e, and Sd respectively, we h^ve the following expression
for the value of the unknown resistance :
Fig. 11. Precise Measurement.
0? =
Sa — Sb
Se — Sd
R.
60
MBASUBEMENT8.
NoTK. — Mr. E. F. Northmp gives the following formula as handy in
determining the percentage conductivity of metal wires. This oonductivitv
is generally expressed as a certain per cent conductivity of Matthiessen^
stands^. To determine the conductivity, a resistance A of a sample is
usually determined at a temperature 20^ C and of a length L From this
measurement the pa* cent conductivity may be expressed as follows:
i> * J *• * _ P X d X 100
Percentage conductivity = ;g^ ^ IF X 581.054'
where I = length in centimeters, W =r weight in grams,
Am = resistance in ohms at 20^ 0, << = specific gravity.
RKSKSTAlfCB OV AAKVAirOMBTBRft.
When a second galvanometer is available, by far the most simple and sat^
isfaotorv method Is to measure the resistance of the galvanometer by any
of the ordinary Whoatetone's bridge methods. Take the temperature at
the same time, and, if the instrument has a delicate system, remove the
needle and suspension. _ ^ . ^ , * i _• —1*1.
Half Deflectton MeiMoA. —Connect the galvanometer in series with
a resistance r and battery as in the following figure.
^ Note the d^ection d ; then increase r so that the new
>.JCr-VVVSAA-^ deflection d^ ^U ^ one-half the first, or | = d^ ; call
Y^ J the new resistance r. ; then
> ^ Resistance of Galvanometer = r. — 2 r.
If the Instrument be a tangent galvanometer, then
d and d| should represent the tazigents of the deflec-
tions.
Kelvin** Method. — Connect the galvano-
meter, «s a; in a Wheatstone's bridge, as in Fig. 13.
Adjust r until the deflection of C7 is the same,
whether the key. is closed or oi>en.
a
The result is independent of the resistanoe of the
battery. The battery should be connected from the
1 unction of the two highest resistances to that of
he two lowest.
RKSISTAliCB OV BATTKRUBA.
Goadeaaer Metlioa. — For this test is needed a condenser C, a balUstle
galvanometer (7, a double contact key *», a resistance -R,
of about the same magnitude as the supposed resistanoe
of the battery B, and a single contact key k^. Connect as
in the following figure. With the key k^ open, press the
key *,, and observe the throw B^ in the galvanometer.
Then, after the needle has come to rest, with key «,
cloeed, repeat the operation observing the throw 9^
Then the resistance of the battery
Fia. 12.
Fia.
x = R^'
»i
Fig.
n««««^« IH»llectlon Mtetliod.-- Connect the
battery B in circuit with a galvanometer G and a resist-
ance r as in Fig. 16. Note the deflection d, and then in- ^^ . _ _^
^«Ma rto r. Sd note the smaller deflection d, ; then, if the defleetions of
^^^ ' the galvanometer be proportional to the currents,
_ r^di - rd
^ - d-d^
-O.
FlO. 15.
If Tx is such that d^ = ^ ,
then
i?=r,-(2r+flf>.
BESISTAirCIt OF BODflB CIRCTTITS.
61
Tlie E JI.F. of the battery is supposed to remain unaltered during the
messorement.
MsBC«*s Heth«Ml. — Connect the battery as x
la Wheatstone's bridge as in Fig. 16. Adjast r until
the deflection of O Is the same whether the key be
dosed or open.
-^ h
Tim £c-r-'
a
The galranometer should be plaoed between the ^*-«'^
pii
lisl
junction of the two highest resistances and that of
the two lowest.
Fig. 16.
while W«rkt«c* — Connect the battery B
alranometer
Jtesuuuaee mm mwOMmirr wane ¥r •ricivr* — «Jounecv tne km
with a resistanee r, and also m parallel with a eondenser C, jralrax
6, snd key k \ shunt the battery through s with key A), as in FIk, 17.
Close the key k, apd note the denectii
ection d of
the galvanometer, keeping X; closed, close kx and
note du the deflection in the opposite direction.
Then tne battery resistance
B = s
d^dx-^
dyt
If r be large, the term -^ is negligible, and
I Mag the multiplying power of the shunt.
le M well tm ]»7H«Bsoa.— With
djnamo or battery on open dircuit, take the Toltage across the terminals
Tith a Toltmeter, and call it d ; take another reading d, at the same points
vith the battery or dynamo working on a known resistance r : then the in-
tvnal resistance B = "7 * r.
In the ease of storage batteries, if the current / be read from an inserted
immetar when charging, the resistance of the battery is
2^ = ^.
ad irtien discharging
B =
\mmTJLMCM ox*
AMMKA^Ms JLEMMB OB HOVAB
GMMGVITA.
•oadni
.—When the circuit has metallic return, it is
ured by any of the Wheatstone's bridse methods, or, if the circuit
can be supplied with current through an ammeter, then the full
of potential across the ends of the con-
ductor will give a measure of the resistance
by ohms law, vis.,
_ . ^ drop in volts
Resistance = — . — .
current
If the circuit has earth return as in tele-
graph and some telephone cirei:dts, then
place far end of the line to earth, and con-
nect with bridge as in Fig. 18.
Then the total resistance x of the line and
Earth'
Fte. 1&
earth, is
b
x^r-
a
If a second line be available, the resistanee of the first line can be deter-
■Uaed separated from tiiat of earth, as well as the resistance of earth.
62
MEASUREMENTS.
Let
r = resist&nce of first line,
n = resistance of second line,
rs = reisistance of earth.
First connect the far end of r and rt tog^ether, and get the total reaistanoe
R] connect r and r2> and measure the resistance Rg, connect ri and r^, and
get total resistance R2, Then if
— 2
ri=T-Ru
rt=T—R,
This test is particularly applicable to finding the resistance of trolley
wires, feeders, and track.
For other methods for resistance measurements see under "Tests with
Voltmeter."
mSA/ilJRlilllE^T OF EM.ECTROinCO'MVS JPOHCE.
Of Batt«rl««. — This can usually be measured closely enough for all
practical purposes by a high class low-reading voltmeter (see Tests with a
Voltmeter).
lVli«atiitoiie'a lVKetlio«l. — Connect the cell or battery to be oompared
in circuit with a galvanometer and high resistance r, and note the oefleo-
tion^; then add another high resistance
-/V^s/4'VN^
R.,
0
r* (about equal to r), and note the de-
flection <ii. Next, connect the cell -with
which the first is to be compared in cir-
cuit with the galvanometer, and connect
in resistance until the galvanometer
deflection is the same as d; then add
further resistance R until the galvano-
meter deflection is the same as a, ; th«i,
if e equals tlie E.M.F. of the first cell,
and E equals the E.M.F. of the cell with
which it IS compared,
ri : R
e
E..
and
Fio. 19.
Or, the electromotive forces are pro-
Sortional to the respective resistance
eflection the same amount.
Ijiiiiiii4eii*« ]iI«tli«Nl, — The two cells Ei and ^2 to be eompared are
arranged as shown io Fig. 10. R^ and R^ are adjustable resistances which
are large, as compared with the resistances of the cells. Ri and R^ are
changed until the deflection in the galvanometer is reduced to lero.
Then
El _Rx
Et - Rt
If greater accuracy be required than that obtained by the above methods,
some potentiometer method may be used,
in which the cell to be measured is compared
directly with a sttandard cell.
Iiord Kajlelflrh'a Compcnaatlom
IHethoil. — In the following diagram let
R and Ry be two 10,000-ohm rheostats, B
be the battery of larger E.M.F. than either
of the cells to be compared, B| he one of the
cells under test, G be a sensitive galvano-
meter, HR be a high resistance to protect
the standard cell, and k be a key. Obtain
a balance, so that the galvanometer shows
no deflection on closing the key k, by trans-
FiQ. 20.
MEASURING CAPACITY.
63
: fening reaiBtance from one box to the other, being careful to keep the sum
of the resistance.? in the boxes equal to 10,000 ohms. Observe the resistance
; ID R and call it R,. Repeat with the other cell ^21 ^^^ c&H ^he resistance
I Rf. Then the CM.F.'s of the two cells
Ei: Ei «- Ri: R^.
Note. — Special boxes are on the market which automatically change the
resistances R and Ri, maintaining the sum of the resistances constant, the
vsiue of the resistance being read directly from the dials.
Direct JtteiaJing' Pot«iitloBi«t«r. — There are many forms of po-
tentiometers available, which are used in connection with a standard cell,
And on which the potential difference to be measured is read directly from
the switch dJalu of the instrument when it is balanced as shown by a gal-
▼iDometer. Such potentiometers generally read to 1.5 volts. To meas-
vc higher voltages than this a volt box must be used, which is simply a
bigb resistance, across which the voltage to be measured is connected.
C'ODnections are brought out from the resistance so as to include a known
ponion of it. having such a value that the potential difference across it
win be less than 1.5 volts. This is then measured on the potentiometer,
ud the value found multiplied by the constant of the volt box.
M«aaBr«»as«iiit of Current Uj Potentiometer. — The current to
be measured is paf»ed through a standard low resistance, say, .01 or .001
olun, and the mfference of potential across its potential terminals meas-
ored by m^ins of a potentiometer. Then the current is by Ohm'a law
R
*here E is the difference of potential as measured, and R the reeistance
«f ibe itandard.
imAAVRiiiC} cAPAcionr.
Arranyeniont of Condenaem. In Pnrallel. — Join like poles
of the several condensers together as
in the figure ; then, the loint capacity
of the set is equal to the sum of the
several capacity.
Total capacity = c + C/ + <^// + <*//<•
Condenacfra In Herlea. — Join
the unlike poles as if connecting up
battery cells in series as in Fig. 22,
then tne joint capacity of all is the
Fio. 21.
rcetpfrocal of the sum of the reciprocals of the several capacities.
Capacity C= ^
W.+^
+ ^
'//
"///
Fia. 22.
Capncltj' bj IMrect lliiicliarg«. —
Charge a standard condenser, Fig. 23, ( « by
» battery E for a certain time, say 30 sec-
(4feis; then discharge it through a ballistic
plFsnometer G ; note the throw d.
X?xt charge the corideiiBer to be measured,
^i, by the same battery and for the same leligth of time, and discharge this
through the same galvanometer noting the throw d| ;
Then C* : C\ :: e^ : d^.
d.
and
C,=
^ d
For Kelvin's and Gott's methods see pages 326-^27, ** Cable
Testing."
64 MBASU&EMENTS.
.Vrtdirv Metli«d. — For comparing the capacities of two oondenMn
a and C, which are approximately the same, connect as in Fig. 94 thioiifl
two rather high induotionless resistances
i?i and R^ to the key k which makes and
breaks contacts at each end. £ is a bat-
tery. A galvanometer is inserted between
the ends of the condensers where they
Join the resistances. Adjust the resist-
ances so that no deflection results when
the key is manipulated.
Then C=C,^. Fio. 24.
»f PotoBtlAl Method. — The capacity of a condenser may b
determined by the following formula:
<^= — - — s
2.303 R log -
«
where C is the electrostatic capacity, in microfarads, of a oondeneer^ thi
potential of whose charge falls from E to e when it is discharged during ;
seconds through a resistance of R megohms.
If C is the known and R the unknown quantity, then
R = —*-
2.303 Jfc log-
a
In measuring the insulation resistance of a short cable by this method, thl
discharge deflection E, compared with the discharge deflection obtained witi
the same battery from a standard condenser, would give the value of h
For long cables, however, this does not give correct results, and the ca-
I>acity must be determined by other methods.
H<SOT]tOHA«irCTIC Ilff]»UCTIOir.
Xaw of iMdvotfoM. — When the magnetic induction or flux inter
linked with an electrical circuit is changed in any manner, an ^ectr»
motive force is induced in that circuit which is proportional in anK>unt U
the rate of change of the flux, and acts in a direction which would, bg
producing a current, tend to opxwse that change.
Symbolically expressed the induced electromotive force in voits ia
n d^
*"" 10" dr
where ^ is the magnetic flux through the circuit, n the ntunber of tura
of wire, and t the time.
Self-induced electromotive forces are those induced in a circuit by changi
in the current in the circuit itself.
C4»efBcdemt of S«lf-IiSil action. — The practical unit of self-inductioi
is the kenry, and is equal to 10* absolute units.
The self-induction m henrya of any coil or circuit is equal numerically U
the electromotive force in volts induced by a current in it changing at th(
rate of one ami>ere per second. Thus the electromotive force in volte pre
duoed in a circuit by a varying current is
' = -^dt'
vehere L is the self-induction in henryt and % the current hi
If ^ = n, ^ represent the flux turns in the circuit,
then ^ = Li X 10".
For example, if a coil have 150 turns of wire, carrying a current of tv
MEASUREMENT OF COEFFICIENT INDUCTION.
65
produeiiis 200.000 linea of force, or 200 kUoaHttMes through it,
the flux turns equal 200,000 X 160 = 30,000.000. and the self-induotion is
tbcrefore
__ ^ _ 30,000,000
L = ^S-. =
lOH ~" 2 X 100,000,000
= .15 henry.
If the current of 2 amperes die out uniformly in one aeoond, then the
deetromottve force induced is
e= L ^ = .16 X 2 = .30 rolt.
L =
10»
wlicn the permeability is unity.
Where » = total number of turns of wire,
n* = number of turns per centimeter length,
A = area of cross section of solenoid.
For mscnetic substances the above equation muat be multiplied by Mi the
permeability of the medium.
laiemta •€ Tke Coefldemt •€ MmAmeH^m,
wlOi
Caimcity. — The coefficient of self-
Fig. 25.
Fio. 26.
iaduetion majr be determined by means of a Wheatstone bridge as follows:
Let A and B, in Fi^. 25, be the bridge ratio arms, Rt the adjustable rheostat.
Cooneet the ciromt to be measured as RL in series with a variable
BoD-iadufltive resistanoe r and n a portion of which rt is shunted by a
<Mdard condenser of capacitj^ C. First balance the bridge for steady
evrents by adjusting Rj,t that is, when the key K is closed continuously.
"ten alter the proportion of non-inductive resistance ri, shunting the
Modenser until no deflection occurs in the galvanometer when the key K
■ open and dosed. Then the self-inductance
Cvtmpmwimmm iHrith Kaown ••If-InducteMce. — Arrange in form
of bridge as shown in Fig. 26, L being the imknown and Li the standard self-
iadiKianee. Adjustable non-inductive resistances are connected in series
«ith them. Call the resistances in each arm R and Rt, A and B are non-
iBdnetive resistances. First adjust to a balance for steadv currents by
rttsnging R and Ri, then adjust A and B until no throw ot the galvano-
juter is observed when the galvanometer key is closed before dosing the
wtery key. Then B vad Ri must be again adjusted for steady currents.
HBAS0KKUKNTH.
^
!' A R
Then ^=b = b;
II t, be oat of Ayrton »nd
Porry'i bdjiutable iit>n<Urdj of
•elf-mduetion (»m Fig. 27), than
the brides can tw baJsand la the
iHmt'^'' "■I' 'a' aUxly eumnt,
ftoa [or tnuuieot auiTe&U by
mryinctba mlf-induction stand-
eoilfl woimd oti BMtioiu of ood-
oeotrie ■pherica] mrfaoea. the in-
nde CDS of which oui be rotated
with refvenee to the outnde oDo,
and thua their enefficicot of in-
dufltion vuied without cha&rinc
tbeir rerirtwice. The Hie u
nilUhwiryB m
, dwrei
i to42
-n the
Fio. 37. Ayrton i
of aitOTuliDa or r«pidly interrupted direct current for tiio bstt«
■howa in Fi^. 2S. The p&rt oA ia & ilide wire wilh telephoae oont
K\ the ML[-induetanc« L uid Li iire eonnected m in the prerioui □
iLli£«r]^
<f the above, which
■le^o"e'ln pta?«' rS
for ^iie bsttery, u
MBA8UBEHBNT OF MUTUAL INDUCTANCE.
67
AlUrsatiiis eurrent, J7, and the same with oontinuous ourrcot, £|, and the
reading oithe ammet^' with the latter, /.
Th
L-
Vjg» - Ex^
2wnl
If the rerifitance Ri be known, and the ammeter be suitable for use with
am
Fzo. 29.
akernating currenta, the switch and non-inductive resistance may be dis-
poised with. We then have L — ~ — ^— ^ . where I* is the value of the
altvoating eurrent.
Note. — The resistance of the voltmeter must be high enough to render
itB eurrent negligible as compared with that through the resistance Ri.
MeaanreaieBt of BlHtiuil MndncteMce.
Connect the two coils whose mutual inductance ia to be determined,
fir^ in series and then in opposition to each other. The self-induction of
escb combination is then measured by any suitable method.
Let M » the mutual inductance between
the two coils.
L ■■ the self-inductance of one coil.
L, "> the self-inductance of the other
coil.
L„ -■ the self-inductance of both coils
in series.
» the self -inductance of both coils
in opposition.
Then nnee L^, — 1/ 4- L/ -f 2 3f
«ad L,„ - L -f i^/ - 2 Af .
Thfon the coefficient of mutual inductance
desired is
-•<//
M
L„ - L
m
Gomparlaon wltls a Kmowb Ca-
_ ici^. — Connect as shown in Fig. 30
vhcre A and Z> are two coils wnose
1
•
~" '
«
umitif.
J
Fia. 30.
Bnitoal inductance M is required. R
■nd Rx Are two adjustable non-inductive resistances and C a standard
condenser placed in shunt to R and R-t. Vary the resistances R and R^
ontil no deflection is observed en the galvanometer when the key is opened
or Closed. Then the mutual inductance is
68
MEASUREMBKTS.
Coi
iriaoa witli Known Self-Induction bj IB
iiMinaon wiui jft.nown neii-mnancvion oj .vndfre. — la
this method the mutual inductance of two coils is compared with the known
self-inductance of one of them. The coil whose self-inductance is known
ia connected as i? in Fig. 31. The other
coil is connected in the battery circuit with
its magnetic circuit opposed to that of the
other coil. Then by adjusting the other
arms of the bridc^e to a balance for both
steady and transient currents, as in the
methods for self-inductanoe, the mutual
inductance is
M ^.
r-f fi
Anotlior lUetliod. — In order that a
balance may be obtained without the incon-
venience of trial and approximation as in
the foregoing method, the batterv circuit
may be shunted by non-inductive resistance as 8 shown in Fig. 32. The
other connections are similar to those of the previous test. The bridge
is first balanced for steady currents in the regular way by adjusting the
resistances Ri, r, and ri, and then 8 is changed until no deflection occurs when
the key is opened or closed. Then the mutual inductance is
Fig. 31.
Af--
LR^S
(Ri + fl)6' + (R + r)«i
Contpniiaon of Mntnal Indnctnni^ wltk Known Solf-Mn-
iiactnnco of Anotltor Cotl. — Connections are made as shown in Fig.
33. One of the two coils whose mutual inductance is to be measured ia oon-
Flo. 32.
Fig. 33.
nected in the battery circuit, and the other in series with an adjustable
non-inductive resistance as a shunt to the galvanometer. The known
self-inductance L is connected in the bridge as A. The bridge is first
balanced, as before, for steady current, then the resistance S is chaoged
until no deflection occurs when the key is opened or closed. Then if iSTbe
the total resistance in the shunt circuit, the mutual inductance is
-- LiR\S
M ■""" "777
iR+Rx)*
Volopliono nCetliod. — As in measurements of self-induotanoe, a tele-
phone may be used in measurements of mutual inductance,^ as shown in
Fig. 34. The coil of known self-inductance L is connected in one arm of
the bridge, as shown at R. The other coil is connected in opposition
to that coil in the main current circuit, the current supplied being either
alternating or a rapidlv interrupted direct current. The non-inductive
resistance and the telephone circuit contact are varied until silence occurs
in the telephone in a manner similar to that described for self-inductance.
MEASUBKMENT OF A.C. POWEU.
69
^
Then if p is the resistance of the slide wire for unit length, and the position
for a baknce is a units from the right as shown, then the mutual inductance
M --
Lap
____ jter. — In measurements of inductance, when balancing for
transient currents the galvanometer deflects in one direction when the
bettery key is dosed, and in the opposite direction when it is opened. To
increase the sensibility of such tests, Ayrton and Perry have devised the
■eeohmmetcr. The battery and galvanometer circuits are each commuted
Flo. 34. Fio. 35. Ayrton and Perry's
Secohmmeter.
■0 18 to prodttce a galvanometer deflection in one direction, and increased
ia amount. This apparatus may be used in connection with any of the
above testa where ^Ivanometers are used, the balance being obtained
when the deflection is reduced to aero. Below is given a description of the
apparatus as shown in Fig. 35.
This instrument serves the purpose of making an alternating current to
on in measurements of self-iiKluction, and of commuting such portion of
tfait current as flows in the galvanometer circuit to a direct current.
The instrument consists of two rotating commutators mounted on one
axii and a train of gears for rapidly driving them. The commutators are
oa the two sides of a cast metal case, one only being shown in the illustration.
They are electrically insulated from each other. The brushes of one com-
mntator are mounted on a disk, which can be rotated through an angle of
90* around the axis. The brushes can accordingly be set so that they will
KTcrse the circuits in which they are connect^ at the same time, or so
that one will reverse at any desired fraction of a period after the other.
The driinng handle may be attached at two places on the train of gears,
thv pving two speeds. A pulley wheel is also provided', which may be
used m place of the handle and the apparatus be driven by a motor.
MMJkSmMMXmwm of POUnER Iir AI^VlSRIf ATIIf«
CimitBira GXRC17IT0.
In alternating current circuits having inductance in any part of the cir-
cuit, such as motors, unloaded transformers, and the self-inductance of the
line itsdf, the product of the values of the current and the E.M.F. as shown
by an ammeter and voltmeter does not give the power in the circuit,
niee the current is not in phase with the E.M.F.
The power at any instant of time in any alternating current circuit is
eooal to the product of the instantaneous values of the current and E.M.F.
This is shown graphically in (Cut A) Fig. 36. The mean power in the circuit is
P ''EI,
vhere B is the effective E.M.F. and / the effective current. The effective
nlueB of E.11.F. and current are the square roots of the mean squares of
their respective instantaneous values, or numerically, their maximum
Tdoee divided by V2 or 1.41. Alternating current measurinia; instruments
of either the "hot wire" or dynamometer type indicate effective values.
If the current is not in phase with the E.M.F.,
m phase is ^, then the power is
P - J?/ cos ^
and the angular difference
70
MEASUREMENTS.
n
\7
/.
* /
^y
.^'
Fio. A.
Fig. B.
-7^
'1 2/''
Fro. C.
Pio. D.
Fxa. £.
Fio. 80.
^
M£A8UH£M£NT OF A.C. POWBB. 71
Cm ^ is oan«d the power factor, since it \b the factor by whioh the apparent
power BI must be multiplied to obtain the true power.
Suppose that curve No. 1 in Fig. B, page 70, represents the various values
of the impressed voltage throughout a cycle, and that curve No. 2 represents
tbe various values ofthe self-induced voltage. Curve No. 2, it will be noted,
if not in phase with curve No. 1. Its highest value comes at a later time
than that of curve No. 1, because the self-induced electromotive force it
never in phase with the impressed electromotive force, as the self-induced
eleetromotive force is obviously at its highest point when the lines of force
induMd by the coil are changin|[ P?*^. "^pidly. This occurs when the
cuiTCDt is rapidly increasing or dimimdbing, and not when it is maintain-
ing a momentarily steady value at its highest point.
Current will flow in the circuit in proportion to, and in phase with, the
resultant of the two curves, and the ordinates of this resultant will be the
&||ebnucal sum of the corresponding ordinate of the two curves. Curve No.
3du>ws the resultant curve constructed in this way. It will be found to be
amilar to the other curves but of a different maximum value, also lagging
behind the curve of impressed E.M.F., but occurring earlier than the curve
of aetf-indueed E.M.F.
la fig. C are shown the curves r^resenting the impressed E.M.F. and
the resulting current, and as will be seen the current lags behind. If
the values of these curves be combined by multiplying them toi^etha*.
ordinate by ordinate, this curve representing power will result. This will
be the true curve of power, as it obviously represents the power at every
instant, the instantaneous voltage being multiplied by the instantaneous
current, and eonsequently takes account of the fact that th«r maxima
■re shifted with reference to one another.
If the current and voltage curves are arranged as shown in Fig. D. in
wbidi the maximum value of the voltage occurs at the same time as does
the minimum value of the current, the result will be as shown, and no
power will be produced.
If the current is in phase with the electromotive force as shown in
Fig. £, the power curve will appear above the aero line, and the true
power will also be the apparent power.
'WMw Voltatetcr Method. JLyrtmwt * flvaipMcr.
This method ie good where the voltage can be regulated to suit the load.
In figure 37 let the non-inductive re-
sistance B be placed In series with the
load a b ; take the voltage V across the
terminals of Ji\ Vx across the load a 6,
and V^ across both, or from a to c.
Then the
True watts = — ? — .
Fio. 37. The best conditions are when V = Tj,
and, itR=:\ ohm,
then ir= r,«— Ki«— F».
C«aiMn«d Vol«M«ter and Ammeter TUmt^mtL
Hiis method, devised also by Fleming, is quite accurate, and enables the
accuracy of instruments In use to be
checked. In Fig. 38 A Is a non-inductive
resistance connected in shunt to the Induc-
tive load a 6, and the voltmeter V mesAures
the p. d. across xy. A and A^ are ammeters
connected as shown ; then
True watts = ^ (a,* -A*-(^)^.
Fig. 38. If the voltmeter F takes an appreciable
amount of current, It may be tested as fol-
towii : disconnect R and V at y, and see that A and A. are alike ; then con-
Met R and K at tf again, and disconnect the load a h. Then Ai = current
taken trr Jt and Fin multiple.
72
ME AS UREMENTS.
WA!rrMKVKIt METHOIMi.
(Contributed by W. N. Goodwin, Jr.)
For meaaurement of power in electric circuits, the wattmeter eivee the
ciiiickest and most accurate reeults. Since the instruxnent mechanically
integrates the products of the instantaneous values of current and E.M.F.,
the power is indicated directly, regardless of the power factor.
When a wattmeter is coimectM to a circuit, the instnunoit itself re-
quires current and. therefore, some power is consumed in it. This error
must be calculated and subtracted from the observed readings. Weston
wattmeters are compensated for this error by means of a ooil wound in
opposition to the field coil and adjusted with it. The following are a few
of the important tests with a wattmeter used in power measurements.
Fig. 30 shows the connections for measurement of power in either m
direct or single phase alternating-current circuit. The power oonsumed
by L is read directly from the instrument.
Fio. 39.
Fxo. 40.
In direct current measurements, to eliminate the effect of the earth's
magnetic field, two readings must be taken; either the connections must
be reversed for the second reading, or the instrument turned 180^ from its
first position; the mean bf the two readings gives the true power.
If the instrument have a multiplier, it should be connected as shown in
Fig 40j so that the difference of potential between the stationary and mov-
able coils shall be a minimum.
Clieoktii^ IVattmeters. — In checking wattmeters either directly with
other wattmeters, or by means of a voltmeter and ammeter, the wattmeter
should be connected so as not to include its compensating ooil. In a Wes-
ton wattmeter the "independent" landing post should be used, shown in
Fig 30, the pressure circuits being connected in parallel and the field or
current coils in series.
Hire«i«PluMe Power llleasiireiiiente. — In unbalanced systems
two wattmeters are required, connected as shown in Fig. 41 . llie totalpower
transmitted is then the algebraic sum of the readings of the two watt-
meters. If the power foctor is greater than .50^ the power is the arith-
metical sum, and if it is less than .50, the power is the arithmetical differ-
ence of the readings.
Fio. 41.
WATTMBTER METHODS.
73
Xterce^yfcwc •TNteaui. — One wattmeter may be used
in three-phase circuits in which tne current lag is the same for all parts
of the circttit and the load is uniformhr distributed. The connections are
ihown in Fi|^ 42. The current coil oi the wattmeter is connected in one
Tb
J^
■•'NXWV^
FiQ. 42.
of the leads as A; one end of the pressure circuit to the same lead, the other
end is connected successively to each of the other leads as B and C, a read-
ioK bains taken in each position. The i>ower is then the sum of the sepa-
rate readings.
•ecMM JHKetkod f«r Jtoliaitced Ctrcnlte. — Another method may
be and by which the power may be obtained from a single reading of the
iiatnunenti as shown in Fig. 43. The current coil of the wattmeter is
eonneeted in one lead as A; one end of the pressure circuit is connected
to the same lead.
FiQ. 43.
The other end of the pressure circuit is connected to the junction of
two renstances r and r, each equal in resistance to that of the wattmeter;
tbe ends of these resistances are connected to the other two leads as
■bown at B and C. llxe power is then
P = 3p
wfwre p ii the instrument reading.
If it be desired to use the instrument for higher voltages than that for
viueh it was designed, then a resistance R must be added to the instru-
i2 -f- r
mnt branch, of such a value that — ■ — is equal to the multiplying con-
stat m desired.
Each of the other two branches must be increased to B-^r,
Then the power is
P = 3 mp.
The Weston *' Y box" multiplier, which may be made for any multiplsong
motant, is constructed according to this principle.
Any of the above methods can be used equally well for the delta as for
UMstiir oonnection.
74
MEASUREMENTS.
The following are a few of the more important testa for which Toltmetcn
and ammeters are especially adapted. With some changes and additions
they have mostly been condensed from an article by H. Maschke, Ph.D.,
of the Western Laboratory published in the Electrical World in April, 1S92.
The scales of the better known portable instruments read, in general,
from 0 to IGO, or some even multiple or fraction of this value. Voltmeters
are available having scales rannng from 1.5 volts to 750 volts for a fall
scale deflection, and when used with multipliers for any higher ranee.
Two or more ranges may be had on the same mstrument, so that by mmply
transferring connections from one binding post to another, voltaces aif-
fering greatlv in amount may be measured on one instrument. Millivolt-
meters may be had reading as low as 20 millivolts for a full scale deflection.
InatnuBenta wltb PermMsent Ma^rnete should not be placed on
or near the field magnets of motors or generators, nor should they be used
for measurements in very strong magnetic fidds, such as those produced
in the vicinity of conductors carrying heavy currents. If the fields be
not too strong, then the error produced in the instrument from this cause
may be eliminated by taking the mean of two readings, one in position,
andf the other when the instrument is turned 180^ from that position aroona
its vertical axis.
Slectroatotlve Farce of IBatteiiea.
The positive post of voltmeters is
usually at the right, and marked +•
In a battery the sine is commonly neg-
ative, and should therefore be con-
nected to the left or negative binding
post.
For single cells or a small number,
a low-reading voltmeter, say one read-
ing to 15 volts, will be used, the con-
nections being as per diagrams.
Klectromotlve
of
WiUJUHh
For voltage within range of the instrument available for the purpose. It ia
only necessary to connect one terminal of the voltmeter to a brush of one
polaritv, and the other terminal to a brush of the opposite polarity, and
read direct from the scale of the instrument. As continuous current volt-
meters usually deflect forward or back according to which pole is connected^
It is necessary sometimes to reverse the lead wires, in which case the polar-
ity of the dynamo is also determined. Of course the voltage across any cir-
cuit may be taken in the same way, or the dvnamo voltage may be taken at
the switchboard, in which case the drop In the leads sometimes enters into
the calculations. Following are diagrams of the connections to bipolar and
multipolar dynamos :
PlO. 46.
Fio. 47.
TESTS WITH A VOLTMETER.
76
In fhe eaae of arc dynaxnoe or other machines giving hish voltage, It is
necessary to provide a multiplier in order to make use of the ordinary in-
strument ; and the following is the rule for determining the resistance
Yhich, when placed in series with the voltmeter, will provide the necessary
raoltiplying power.
Lst e = upper limit of instrument scale, for example 150 volte,
E = upper limit of scale required, for example 760 volts,
R = resistance of the voltmeter, for example 18,000 ohms,
r = additionid resistance required, in ohms.
Then
r==Ji^-J5orr==18/)Oo5?^gJ!5? =72,000ohms.
J? TfiO
The multiplying power = — or -^^ = S.
Should the exact resistance not he availahle, then with any available
mistaooe r^ the regular scale readings must be multiplied by ( ^ + I ] •
of Hlrli BeaiateBce for Volta
5 .-A/WVsA/VA— A
It is highly important, as reducing the error In measurement, that the in-
ternal resistance of a voltmeter be as high as practicable, as is shpwn in the
following example :
Let £ in the figure be a dynamo, battery, or other
KKiroe of electric energy, sending current through the
reHBtance r; and vm. be a voltmeter indicating the
pneeore in volts between the terminals A and B. Be-
fore the vtn. is connected to the terminals A and B there
will be a certain difference of potential, which will be
kas when the voltmeter is connected, owing to the les-
Beniiig of the total resistajice between the two points :
if the resistance of the vm. be high, this difference will
be Tery small, and the higher it is the less the error.
Following are the formulas and computations for de-
tenaining the error.
In Fig. 48 let £ be the E.M.F. of the generator,
r the resistance of the circuit across A and B when
the difference of potential is to be measured, Vx the
raistance of the Mads, generator, etc., and R the remstance of the volt-
Bicter. Before the vm. is connected the diflerence of potential between
AaodBis „
r + rj
With the roltmeter connected the difiference of potential indicated by
the instrument is
V,-
Fio. 48.
rRE
tR + Tir + TxR
The voltage aeroes A and B is, therefore, reduced by the introduction
*ie amount of
rvxVx
(tf the voltmeter by the amount of
V-Vx
The error is
{X'\-rx)R
100
(^)
lOOrr,
U
Vx / (r-f ri)ft
The error is inversely proportional to the resistanoe R of the yoltmeter.
Example :
E "10 volts,
r — 10 ohms,
ri *- 2 ohms,
R — 500 ohms.
IhsQ the reading of the voltmeter is
„ 10 X 500 X 10 n -rtRft ^^u-
^'"(10 X500)-K2 Xl0) + (2 X500)"^-^^^^'*^
76
and the error ia
MEASUREMENTS.
y _ K. - ^^4441^ - .0277 volt..
and the percentage error is
P =
(10 + 2) 600
100 X 10 X 2
aO-f 2) X600
If R be made 1000 ohma. then
,, 10 X 1000 X 10
\ ^ mm
-.333%.
and the error is
and the percentage error is
(10 X 1000) + (2 X 10) + (2 X 1000)
— 8.32 volU
V^ -V - ^?.^^,^J^,^^?? - .01387
P -
(10 4- 2) 1000
100 X 10 X 2
- .166%
(10 + 2) X 1000
or just one-half the error with R — 5(X) ohms.
If the error of measurement is not to exceed a stated per cent p, then r
an:i ri must be such that n
I * is less than :^-
r-j-ri 1(X)
If the circuit is closed by a resistance ri, and it be deared to measure
the E.M.F. of the generator by connecting the voltmeter between any
two points as A and B, then E '^ ( — ^^— * ) Vi, where Vi — reading on rm.
The error between the true value of the E.M.F. of the generator and that
shown by the voltmeter is t^
{^
R
and the percentage error p °« 100
If the error is not to exceed p per cent, then the resistance of the gen-
erator, cables, etc., must not exceed -—z-
For example, with a voltmeter having 15,000 ohms for 150 volts; if p
— 30 ohms.
must be less than i%, then r^ may be fts great as
i X 15000
100
CoBip»riiiOM of IRJIK.V, of liatterltw.
l«'h«at)iitoii^*ii lUethfid. — To compare E.M.F. of two batteries. A and
X, with low-reading voltmeters, let £ be the E.M.F. of A, and E\ the E.M.F.
of X.
■V^/W^AAAAA^
Fxo. 40.
First oonneot battery A in series with the voltmeter and a resistance r,
switch B being closed, and note the deflection K; then open the switch B^
and throw in the resistance r^ and note the deflection T,. Now connect bat-
tery X In place of A^ and close the switch 5, and vary tne resistance r until
the same deflection Fof voltmeter is obtained and call the new resistance r. ;
next open the switch B, or otherwise add to the resistance r, until the deflec-
tion f\ of the voltmeter is produced ; cull this added resistance r„ then
E -.Ex ::r, :r,.
If E be smaller than i^,, the voltmeter resistance R may be taken as r, and
it is better to have r^ about twice as large as the combined resistance of r
and the resistance of A.
It is not necessary that the Internal reBistance of the cells be small as
compared with R.
^
TB8XS WITH A VOLTMETER.
77
PonremdorlTB MetMoA HodUlcA by Clark.
Ite Compare the EJtf .F. of a battery cell or element "with a standard oelL
Let i9 be a standard cell,
7* be a cell for comparison -with the standard,
^ be a battery of hfsher E.M.F. than either of the above elements.
A reaistaaee r ts joined in series with the battery B and a slide wire A D,
A mflllToltmeter is connected as shown, both its terminals being oonnected
to the like poles of the battery B and the Standard S.
Fig. go.
MoTe the contact C along the wire nntil the pointer of the instnunent
ituids at zero, and let r^ be the resistance of A C.
Throw the switch 6 so as to cut out the standard S^ and cut in the cell T\
now slide the contact d alons the wire until the pointer again stands at
SHO, and call the reelstance oi ^ <7i r,,
Then the £.M.Fb. of the two cells
T: S ::r, : r,.
If a meter bridge or other scaled wire be used in place of A 2>, the results
nay be read directly In yolts by arranging the resistance r so that with the
pointer at zero the contact C is at the point 144 on the wire scale, or at 100
tim«8 the E.M.F. of the standard 8, which may be supposed to be a Clark
«eQ. All other readings will in this case be in hundredths of volts ; and
dwald the location of Cx be at 175 on the scale when the pointer is at zero
mlhemllliToltmeter then the E.M.F of the cell, being compared, will be
LISTOltS.
MMksvrlaff Curr«Bit fitr«Mr<b witli i» Voltmeter.
H the resistance of a part of an electric circuit be known, takine the drop
la potential around such resistance -will determine the current flowing by
ohms law viz., /= -^ .
In the figure let r be a known resistance be-
tvwD the points A and B of the circuit, and /
fteitrengtn of current to be determined ; then
if tiie Toltmeter, connected as shown, gives a
MtftjiTn of V volts, the current flowing in r
viUbe
r
For the corrections to be applied in certain
ciMs, see the section on Importance of High
BaUbuux for VoUmeters. page 75.
Always see that the reelstance r has enough
eurying capacity to avoid a rise of temperature
vfaieh -woold change its resistance.
If the reading is exact to — volt the meas-
^ 1
srement of current will be exact to z-rr^ *™-
ff WVS/WNA/WNAAA* 00
FlQ. 51.
78 MEASUREMENTS.
peres. Ji r^JH ohm, and the readings are taken on a low-reading volt-
meter, say ranging from 0 to 5 volts, and thai can be read to sio volt, thea
the possible error will be
300XT *" fso '"P*'*-
If rbe made equal to 1 ohm, then the volts read also mean amperes.
]IIeaa«v«Hi«Bt •€* Cvrreat with m HlllllT^ltiii^ter. — This ia the
method generally used in practice for the measurements of currents, and
is the same principle as the one outlined above with the substitution of a
millivoltmeter for the voltmeter.
As the drop is much lower, a comparatively low resistance shunt may
be used, so that heavy currenta mjfty be measured without thediunt becom-
ing disfH'oportionately large.
For portable instruments, detachable shunts are generally adjusted with
the instrument so that the instrument scale reads directly in amperes, llie
shunts are constructed of resistance alloy having a negligible temperature
ooeflScient.
Switchboard instruments also have shunts with slotted terminals ao
that they may be connected directly to the bus-bars.
In some cases where the currents to be measured are very large the in-
struments are adjusted to the drop across a portion of the copper bus-bar
through which the current passes. To compute the leni^th of the copper
bar of a given cross section to give a certain drop for a given current,
let i4 » the area of the cross section of bar in square inches,
/ — current in amperes,
V ■■ drop in millivolts desired for instrument for current I;
then, length in feet - ^^ ^ "^ at 20" C.
HteaaviiMiT nealateMoe witli » Voltmeter.
d«ii«Tml Metlioda. — In the figure, let X = the unknown reeistance
that is to be measured, r = a known resistance, E, the dynamo or other
steady source of E.M.F.
f. When connected as shown In the figure, let
the voltmeter reading be V ; then connect the
voltmeter terminals to r in the same manner
and let the reading be F^ ; then
X:r::F:Fi
and X = '^.
If, for instance, r = 2 ohms and F = 3 volta
and Fj = 4 volts then
X
— VNAAAAAr
'A/^NSr-^
Vm,
FlO. 62.
ji:=?^= 1.5 Ohms.
If readings can be made to ^ volt, the error of resistance measuremant
will then be P
100 X J- 1^^+ jrj per cent.
and for the above example would be
1 (i + J) = 0.68%.
Should there be a considerable difference between the magnitudes of the
two resistances X and r. it might be better to read the drop across one of
them from one scale, and to read the drop across the other on a lower scale.
Re«tataBc« HIeaaiir«ai«iit witM Voltmeter and Ammeter.
The most common modification of the above method is to insert an am-
meter in place of the resistance r in the last figure, in which case X=z-f
where / is the current flowing In amperes as read from the ammeter.
TESTS WITH A VOLTMETBB.
79
If tfae readings of the roltmeter be correct to — and the ammeter read-
P
ings be correct to the same degree, the possible error becomes :
100 Xj ( ^ + i) per cent.
lest of T^wy AnuUl
ilstancea witli
a MUltTolt-
By using a milUyoltmeter In connection with an ammeter, Tery small re-
fistances, such aa that of bars of copper, armature resistance, etc., can be
ftccnrately measured.
sio.6a
In order to have a reas-
onable de^ee of accuracy
in measuring resistance by
the " drop" method, as this
is called, it Is necessary
that as heayy currents as
may be available be used.
Then, if iP be the dynamo
or other source of steady
E.M.F., X be the required
resistance of a portion of
the bar, V be the drop
in potential between the
points a and 6, and / be
the current flowins in the
circuit as indicatea by the
ammeter, then
lbs applications of this method are endless, and but a few, to which it is
ttpedally adapted, need be mentioned here. They are the resistance of
armatures, the drop being taken from opposite commutator bars and not
from the brush-holders, as then the brush-contact resistance is taken in : the
ratfttsuice of station instruments and all switchboard appliances, sucn as
tbe resistance of switch contacts ; the resistance of bonded Jotuts on electric
nOway work, as described in the chapter on railway testing.
mm
irenseat of Hlfli IleaiateBcea.
WiUi the ordinary voltmeter of high internal resistance, let R be the re-
Bstance of the voltmet^*, X be the resistance to oe measuredi. Connect them
ap fai series with some source of electro-
aotiye force as in the foUowins figure.
Cloee the switch 6, and read tne voltage
r vith the resistance of the voltmeter
thne in drcuit; then open the switch,
Uioi cutting in the resistance X, and take
ttofher reMing of the voltmeter, V,,
Tta X=b{^-i).
FlO. 64.
If the readings of the voltmeter be cor-
rect to - of a volt the error of the above
p
nnltwiUbelODx-jr (y"^ p) percent.
Vef7 Higrii nealatWBce. — For the measurement of very high resis-
tsDCSB a more sensitive voltmeter will give much bett^- results for the reason
thst the reading Vi when the switch h is opened, becomes so small with the
ordhiary voltmeter that the error is relatively very great. Instruments are
<m the market having a sensibility of 1600 ohms per volt or about 260,000
ohPH for 150 volts.
80
MBASUREMENTS.
For example if x — 1 mesphm and an ordinary voltmflier be used
R ^ 15,0(X> ohms for 150 volts,
and Z — 120 volts.
ER 120X15.000 . 1.772 Tolta;
whUeif
Vt would be j^ _j_ ^ 1 ,000,000 + 15,000
R were 250,000 ohms.
120 X 250,000
Vi would be
» 24 volts.
1,000.000 + 250.000
that is with the high resistanoe instrument, with the same aoearaey of
the instrument soales, the percentage error is about ^ as great as with the
lower resistanoe instrument.
Meaavrteg' tlie Mnaulatloa SeeiatAiic« of lAtflMUmtr wtmd.
Power Clrcvita wltli m Voltmeter. — For the measurement of in-
sulation resistance, a high resistance sensitive voltmeter is needed. For
rough measurements where the exact insulation resistanoe is not reauired
but it is widied to determine if such resistance exceeds some stated figiure,
then a voltmeter of ordinary sensibility will answer. The methods in general
are as follows :
Let X ■• insulation resistance to ground as in Fi|(. 55,
Xi » insulation resistanoe to ground of opposite lead,
R — resistance of voltmeter,
V — potential of dynamo E,
Vt -> reading of voltmeter, as connected in figure,
Vi ■• reading of voltmeter, when connected to opposite lead.
Fig. 66.
"^" AfVlfMl
Then
and
The above formula can be modified to give results more nearly eon«et by
taking into account the fact that the path through the resistance R of the
voltmeter is in parallel with the leak to ground on the side to which it to
connected as shown in the following figure :
"^Ground
FlO. 66.
Ground "^
TE8T8 WITH A VOLTMETER.
81
1
In tUa ease the Toltage V of the circuit will not only send current through
the lamps, but through the leaks ef to ground, and through the ground to
d and c, thenoe through 4 to 6, and c to a, these two last paths being In par-
allel, therefore harlng less resistance than if one alone was used ; thus if r
he the resistaaee of the ground leak b d^ and rj be the resistance of the leak
f /• aad JK be the reslstanoe of the yoltmeter, then the total resistance by
way of the ground, between the conductors, would be
i2-|-r + *^»»
F= Toltage of the circuit,
V =r reading of roltmeter from a to 0,
V, = reading of roltmeter from gtoe.
=«(
r-(»+r,)
)•
Thesum of the resistance r + r^ will be = JS
(
)
Seel«tsft»c« of Are IilrM Ctac«lt«.
Are lamps are to a great extent run in series, and the Insulation resis-
taaee ot their circuits is found in a manner similiar to that for multiple
cfanrits, hut the formula differs a little. Let the following figure be a
tnieal are cfrenit, with a partial ground at c.
ttast fliid the total Toltage K between a and b of the circuit. This can
WMt handily be done with a voltmeter having a high resistance in a sepa-
Bte box and so calibrated with the yoltmeter as to multiply its readings l>y
FlQ. 67*
eomreniMtt number. For oonrenience in locating the ground, set the
voile per lamp by dividing the total Tolts V by the number of lamps
M the drevit ; the writer haa found 48 volts to be a good average for the
flidtavy 10 ampere lamp. With the 16 lamps shown in the above figure, V
eeeU probably be about 768 volts.
Sest take a voltmeter reading from each -end of the circuit to ground.
Can the reading from a to ground v, and from b to ground v,^ R b^g the
s ot roltmeter as before, and r the insulation resistance required.
.=.(
)•
; the location of the ground, provided there be but one and the jB^eneral
of the circuit be good, will be found closely proportional to the
V aad V/ ; In the aoove figure say we find tne voltmeter reading
frail 0*10 gronnd to be 38, and from b to ground to be 36 ; then the distance
•< the gnMBd e tnmk the two ends of the circuit will be in proportion to the
nadtagi S8 and m respeetirely.
Itee being 16 lamps on the oironlt, the number of lamps between a and c
82
UEASVREMES TS.
^°?^oJ^ ^.•^-^"♦"2^ = M of 16 = 7, «nd from 6 to c would be 36-^
(28 + 36) = If of 16 = 9 ; that la, the ground would most Ukely be found be-
tween the Beventh and eighth lampe, counting from a.
lBs«]»tlo» acr«M a Doable Pol« Fane Block or Otker
Similar Bevico wfeiero Botk TonMiaalii are on
tihe Same liaeo.
Let// be fuses in place on a base,
V = potential of circuit,
R = resistance of voltmeter,
w = reading of voltmeter,
required the resistance r across the base
a Of to ft &,.
Then r^R^"^
V
FlO. 68.
JHSASURBMBITT OF THB nVdlTIiA'nOir RKAIS.
TAH CS OF Air EI<BCTItICWIJU]!f« ftYSVIDMt
iriTH VHB JPO^TBli OH.
The following methods have been devised by Dr. Edwin F. Northnip
for the measurement of insulation resistance of a circuit where it is im-
practicable to shunt ofif the current.
1. — Voltmeter HEetiiod.
Let A (Fig. 59) represent any wiring
system in which Xi and X2 are the
insulation resistances between the bus-
bars, Bi and Bg and the earth (the
gas or water pipes beins taken as at
the potential o! the earthT. In Fig. 50,
/, //. and /// are equivalent diagrams
in which y represents the unknown
resistance of all the lamps, motors,
etc., across the line.
If direct current is supplied to the
bus-bars, a direct-ciirrent voltmeter
should be used. If the current is
alternating, then an alternating-cur-
rent voltmeter will be required. The
resistances, Xi and Xs, are determined
by knowing g, the resistance of the
voltmeter, and by taking three volt-
meter readings.
ist. Measure the voltage, which
we will call E, across the bus-bars
(Fig. 50) /.
2d. Connect the voltmeter be-
tween the bus-bar, Bi, and the earth
and take its reading, which we will
call Vt (Fig. 60) //.
3d. Connect the voltmeter be-
tween the bus-bar, B2, and the earth
and take its reading, which we will
call Vf (Fig. 59) ///.
If the readings in either of the two
latter cases are only a fraction of a
scale division, then the insulation re-
sistance is too high to be measured by
this method ana we may resort to
'j?'i f'H ^ ^
4!^0mmmi^
I B,
fmEADSE
Xi X,
f READS Yl
B.,
.'/
II B,
Xi
«MWMWWWWWIWW<WWW»»^
II-
B.
«>«READSV,
m
. Ca
ci
.'/
„..Ca
Xi X,
w
B.
Fio. 50. Voltmeter Method.
MEASURING INSTTLATIOX RESISTANCE. 83
Uieaeeood method to be described. Having taken the above three read-
ioc*. it can be ahown that
_ fJB - V. - V,l
The carreat /, which leaks to the ground will be^
Xi -\- X2
Per example, the insulation resistance of the wiring system of a large
ofBee buildmg was determined by means of a Weston voltmeter, the fol-
loving readings and resistanceB were obtained:
a — 12,220 ohms,
E - 113 volts,
Vi - 1 volt,
Kj "" 4 volts.
X. _ 12.220 018 - 1 - 4) _ 329.940 ohm..
y^ _ 12.220 (113 - 1 - 4) _ ,3,,^^ ^^^
The above example shows that where the sum of the resistances, Xi
and Xt, are not over one or two million ohms, the voltmeter method is
wffidently accurate for the purpose. If one side of the line is grounded —
tkat is« if Xz « 0 — then from (2) E - V, + Vj - Vi, as fa - 0, and
the metbod fails to give Xi,
Expressions (1) and (2) above are obtained as follows: The meaning of
the mters used are indicated in /, //, and /// (Fig. 59), Ci, Ca, etc., being
earrents and g the resistance of the voltmeter.
c. *
x,+ '^'
Xi+a
C B
Uj ^ ■my '
, or Ci - ^
. or Cj « -^
d ^
iff + xo
Xi g
ig-^x^)
Xig
X,+
gXt
*" Xag
Xa-i-g
^* 'liTXt'l
ff + JTa ' g
Heoee, we have the two relations,
X 4- ^^* •** ^
Xj + 0 X2 -r V
firom whieh the values for X* and X2 are obtained as given above in equa-
tioDi (1} and (2).
'Any uutrument, as a galvanometer, in which the deflections are pro-
portional to the currents, may be substituted for a voltmeter. In such a
ease, if D, dt, and d^ are deflections corresponding to the readings £, Fi,
tod Vt, and O ia the total resistance in series with the instrument, we have
u before:
X «- ^ (^ "" ^1 " *^»^ (3)
«d X,- g (P -/. - <<.) (4)
84
MEASUBBMENT8.
If two or more electric lamps are connected in series, their resist^noeB,
while carrying current, can be determined by means of three readings,
as above.
If X2 <*• 00, Vt •■ 0, and Xi — ^-^ — p ^1 which is the ordinary ex-
V 2
pression used in measuring a resistance with a voltmeter by reading the
voltmeter with the resistance in series with it and again with the resLstance
out out.
n. — OalTaiiOVi«ter Metliod.
This method may be used when greater accuracy is reqtured or when
the insulation resistance to earth, of at least one side of the line, is over a
megohm.
Tlie wiring; system is represented in 1 of Fig. 60, and 2 of Fig. 60 gives
equivalent circuits.
The method consists in connecting across the bus-bars a moderately
lugh resistance and finding on this resistance a point, p, where the poten-
tial due to the generator vb the same as that of the earth, and then with
Fio. 60. Galvanometer Method.
the aid of a sensitive galvanometer and an external source of E.M.F.. meas-
uring the resistances. Vi and r^, to earth in the following manner: A; is a key
and S an Asrrton universal shunt. This latter may be omitted if the aouree
of E.M.F. can be varied in a known planner.
It is evident from Fig. 60 that a balance will be had when ? — ^ ,. the
key, k, being in its upper position. If k is now depressed, the resistance,
R, encountered by the current generated by the source, e, will be
fi - J^i +
1
1
1
6 -f rj o + ri
where gt is the resistance of the galvanometer; but in comparison with
Ti and r2, i7i, a and 6 can be n^Iected, and «
R -
r,r2
By construction, - -^ r >■ AT, a known ratio. From the last two rola-
Tj O
tions we deduce
fa — -
and
N
r, -/2(JV + I).
Taking d as the deflection of the galvanometer and K as the galvano-
meter constant, the current through the galvanometer is
^-^.or/?--^..
MSASITBING INSULATIOS- BESISTANCE. 86
K should be defined aa the reeUtanee which muBt be inserted in circuit
with the galvanometer Cincludinc its own resistance), so that it will give,
with one volt, a scale deflection of one scale division at the distance at
whidi the scale is placed from the mirror during the test, usually taken
as one meter.
Then we will have:
eKiN + 1)
r, --
sad rt —
Nd
eK iN + 1)
Tkking K ■■ 10* as an average value for an ordinary D'Arsonval gal-
vaoometer and « >" 100, n — 2, and d — 100, we have:
100X10»(2 + 1) ,^ ,
''» 2X100 150 megohms.
r.-^^^y-^^^- 300 megohms.
This example shows that a salvanometer of very moderate sensibility
will measure in this wav a very nigh insulation reelstanoe. If, on the other
hsod, the insulation is low, nmall battery power may be used or the defleo-
ticnt of the galvanometer can be out down to V^t ihtt ii(ira> or iphn by the
Ayrton shunt. The only difficulty likely to be experienced in applying
the shove method is that, while ynttttinf^ the test, the relative values of r*
sad Tf wiU keep changing, due to motors or lights being thrown on or on
tbc line. In this event it is only possible to obtain a sort of average value
(or the resistance to earth of eaush side of the line.
la the United States It is unite common to specify that the entire installa-
tios vben connected up shall have an insulation resistance from earth of at
kiit one megohm.
The National Code gives the following :
The wiring of any building must test free from grounds: I.e., each main
npply line and every branch circuit should have an insulation resistance of
•t MMt 100,000 ohms, and the whole Installation should have an insulation
radfttance between conductors and between all conductors and the ground
(not including attachments, sockets, receptacles, etc.) of not less than the
foUoving:
Up to 5 amperes . . 4,000,000. Up to 200 amperes . . 100,000.
Up to 10 amperes . . 2,000,000. Up to 400 amperes . . 60,000.
Up to 25 amperes . . 800,000. Up to 800 amperes . . 26,000.
Up to 60 amperes . . 400,600. Up to 1,000 amperes . . 12,600.
Up to 100 amperes . . 200,000.
All cutouts and safety devices in place in the above.
Whsre lamp-sockets, receptacles, and electroliers, etc., are connected,
CM>hsU of the above will be required.
PiufsMor Jamison's rule is :
Bceistance ttom earth = 100,000 x E-^-^-
nimiber of lamps '
KsDipe'sruleis: —
Besistanoe in megohms = i: ^-. .
number of lamps
A rale for use in the U. S. Navy is :
BesisUnee = 800,000 X
number of outlets
S6
MEASUBBMENTS.
Institation of Blectrical Engineers* rule is :
7900XE.M.F.
Ji.
the least li*
number of lamps'
Phoenix Fire, Office rule for circuits of 200 volts is that
12.5 i|pegohni8
number of lampH*
Twentv-five English insurance companies have a rule that the leakage
from a circuit shall not exceed t^hw pBrt of the total working current.
Below is a table giving the approximate insulation allowable for circuita
having different loads of lamps.
For a circuit having—
26 lamps, insulation should exceed
GO lamps, insulation should exceed
100 lamps, insulation should exceed
600 lamps, insulation should exceed
1000 lamps, insulation should exceed
600,000 ohms.
250,000 ohms.
125,000 ohms.
26,000 ohms.
12,000 ohms.
All insulation tests of lighting circuits should be made with the working
current'. (See page 80, voltmeter test.)
In the following table Uppeubom shows the importance of testing with
the workinx voltage.
Table 1. snows the resistance between the terminals of a slate cut out.
Table IX. shows the resistance between two cotton-eovered wires twisted.
]
•
.,. 1
Volts.
Mbqohms.
Volts.
M BO OHMS.
6
10
13.6
27.2
68
63
45
24
5
10
16.9
27.2
281
188
184
121
M«itiiariii|r thm Innalatlon of l>jB«nao«.
Tlio same formula as that used for measuring high resistances (see Fig.
5o) applieH equally well to dettTmlnlng the insulation of dynamo conductors
from tlie Iron btHly of the machine.
Fig. 61.
Connect, as in Fig. No. 61 » all symbols having the same meaning a«
before.
Let r = insulation resistance of dynamo, then
r=7j(-,':-l).
M2ASUBINQ INSULATION RESISTANCE.
87
turn MmrnmUmHawt ]KestoteBC« mf Blotors.
Where motors are eonneeted to isolated plant oirculte irith known high
intnlatlon, the formula used for insulation of dynamos applies ; but where
the motors are connected to public circuits of questlonaDlo insulation it is
aectsisry to first determine the clreuit insulation, which can be done by
vrinf the connections shown In Fig. 66. Fig. 62 shows the conne<^tions to
motor for determining its insolation by current from an operating circuit.
Fig. eXL
Here, as before, the insulation r of the total connected devices =
.(z-i).
If r= total resistance of circuit and motor in multiple to ground, and r,
is the insulation of the circuit from ground, then X, the bisulation of the
■otorwiUbe X=^^^^^.
X«anu«Bs«Bt of th« Intoroal lt«aleta»ac« of m MmtUiry,
Is the following figure (No. 03), let E be the cell or battery whose resistance
is to be measured, a be a switch, and
. r a suitable resistance.
^k N Let V = the reading of yoltmeter
* ■ with the key. A", open
(this is the E.M.F. of the
battery), and
F^ = the reading of yoltmeter
with key, /T, closed (this
is the drop across the re-
FlO. 63. sistance r),
Then the battery resistance
F— V
r,=:rx — jT — - ohms.
The same method can be used to measure the interna! resistance of
OTosiDas. An ammeter may be connected in the r circuit, in which case
F — V
h ■ i — - where / is the reading in amperes.
CmrnAmtUritj with a IHllIlvoltaietcr.
This is a quick and conyenient method of roughly comparing the conduc-
tMty of a sample of metal with that of a standardpiece.
In Fig. 64, /7 is a standard bar of copper of 100% conductivity at 70° F.;
tUs Imu- may be of convenient length for use in the clamps, but of known
eroM section. X is the piece of metal of unknown conductivity, but of the
88
MEASUBEMBNTS.
■ame croM section u the standard. J? Is a souroe of steady carrent, and if
a storage battery in arallable It is much the better for the purpose. AT U a
mUllToTtmeter with the contact deyice d. The distance apart of the tvo
pointe may be anything, so long as it remains unaltered and will go between
the clamps on eitner oi the bar*.
Now with the current flowing through the two bars in series the fall of
potential between two points toe same distance apart and on the same flow-
FlG. 64.
line will, on either bar, be in proportion to the resistance, or in InTerse pro-
portion to the conductivity ; theref orcf by placing the points of d on the bars
in succession, the readings of the millivoltmeter will give the ratio of the
conductirities of the two pieces.
For example: ^ ..,. ,
if the reading from /? =? 200 millivolts,
and the reading from X=zW5 millivolts,
then the percentage oonductivi^ of JT as compared with B is
205 : 200 : : 100 : conductivity of JT,
or — goS — ^*^*^
MAQNBTIC PROPERTIES OP IRON.
BBVI8£D bt Townsknd Wolcott.
With a giren excitation the flux ♦ or flnx-^ensit^CEof an eleetromagnet
will d^MDiT upon the quality of the iron or steel of the core, and is usually
iBted as compared with air.
If a solenoid of wire be traversed with a current, a certain number of
magnetic lines of force, JC* will be developed per square centimetre of the
core of air. Now, if a core of iron be thrust into the coil, taking the place of
the air, many more lines of force will flow ; and at the centre of the solenoid
these will be equal to(j^ lines per square centimetre.
As iron or steel varies considerably as to the number of lines per square
centimetre (]^ which it will allow to traverse its body with a given excitation,
its conductivity towards lines of force, which is called its permeability ^ is
BQiBeilcaLlly represented by the ratio of the flux-density when the core is
presoit, to the flux-density when air alone is present. This permeability
li represented by «&.
The permeability |t of soft wrought iron is greater than that of cast iron ;
and that for mild or open-hearth annealed steel castings as now made for
dynamos and motors & nearly, and in some cases quite, equal to the best
soft wrought iron.
The number of magnetic Unes tuat can be forced through a given cross-
leetion of iron depends, not only on its permeability, but upon its satura-
tion. F6r instance, if but a small number of lines are flowing through the
Iron at a certain excitation, doubling the excitation will practically double
the lines of force ; when the lines reach a certain number, increasing the
excitation does not proportionally Increase the lines of force, and an excita-
tion may be reached after which there will be little if any Increase of lines
of foree, no matter what may be the increase of excitation.
Iron or steel for use in magnetic circuits must be tested by sample before
■By aoeurate calculations can be made.
IHito for C&-3C Cnrwes.
▲verage First Quality American Metal.
(Sheldon.)
w5
^3i
u4
Cast Iron.
Cast Steel.
Wrought Iron
^heet Metal.
oc
1=1
^1
ilomax-
ells per
sq. in.
4
5|
Xi
■"
t0
\<>
60
74.2
~i3".cr
\^^
be
14.3
wl
10
7.95
20.2
4.3
27.7
11.5
83.8
92.2
»
15.90
40.4
5.7
36.8
13.8
89.0
14.7
94.8
15.6
100.7
30
23.^6
60.6
6.5
41.9
14.9
06.1
15.3
98.6
16.2
104.5
40
31.]»
80.8
7.1
45.8
15.5
100.0
15.7
101.2
16.6
107.1
SO
».75
101.0
7.6
49.0
16.0
103.2
16.0
103.2
16.9
109.0
SD
47.70
121.2
8.0
51.6
16J>
106.5
16.3
105.2
17.3
111.6
10
55.6.141.4
8.4
63.2
16.9
100.0
16.5
106.5
17.6
112.9
80
83.65i 161.6
8.7
56.1
17.2
111.0
16.7
107.8
17.7
114.1
W
71.60,181.8
9.0
58.0
17.4
112.2
16.9
109.0
18.0
116.1
MM
79.50
202.0
9.4
60.6
17.7
114.1
17.2
110.9
1S.2
117.3
m
119.25
903.0
10.6
68.3
18.5
119.2
18.0
116.1
19.0
122.7
no
150.0
404.0
U.7
75.6
19.2
123.9
18.7
120.8
19.6
126.5
»>
198.8
506.0
12.4
80.0
19.7
127.1
19.2
123.9
20.2
130.2
300
238.5
606.0
13.2
85.1
20.1
129.6
10.7
127.1
20.7
133.6
JC = 1.267 ampere turns per cm. = .495 ampere turns per inch.
80
HAGNETIU PKOPBRTtES OF 1
ii
^
1
i
. 1
'
5
--
i
[i
"•:;
—
j|l
-
■
\
1
p
--
>
1
«i
si*
' ^1
\
■fU
\
^i\\
!\
■u
\"
-F
1
i\
s
\\
-
n\ 1
\,
VMii
\
--
J \
"
\\ '
1
\
'V V
1
^^■^
__
+]^
=:=
-■^4
-
-
^
J
L-
r"
^^
-
T i s
"
-
Fro. I. HacDatle Propartla ot Ii
HAONKTIC TEST METHODS.
91
In Izrge genermtora, haytnir toothed armaturee and Ime flux densities In
th« air-gap, the flux is earned chiefly bv the teeth. Tms results in a very
hlfl^ tooth flux density, and a corre^pondinely reduced permeability. The
rebted raluee of (]^, Jji£, and ft are given In the following table. These
rallies are for average American sheet metal.
PenH«al»IUtjr »t Hlrh Flax ]»ciBaM|ea.
Ampere
Ampere
(B
.Kilomax-
je
Turns per
Turns per
Kilo-
wells per
M
cm. Length.
Inch Length.
gausses.
Square in.
200
159
404
19.8
127
99.0
400
318
806
21.0
136
52.5
eoo
477
1212
21.5
138
35.8
no
637
1616
21.8
140
273
1000
795
2020
22.0
142
22.0
laoo
954
2424
22.3
144
1.8
1400
1113
2828
22.5
145
1.6
OS* I»ETSRllfI!VMW« THE 9fA«lfStnC
4fcUAI«ITIBS OF XROM AMD SVEKI..
The methods of determininz the magnetic value of iron or steel for elec-
tro4iuignetic purposes are divided by Prof. S. P. Thompson into the follow-
ing classes : MagnetometriCj Balance^ Ballistic^ and TYactUm.
The first of these methods, now no loneer used to any extent, consists in
eslealating the magnetisation of a core irom the deflection of a magneto-
metw needle placed at a fixed distance.
In the Balance class, the deflection of the magnetometer needle is bal-
anced by known forces, or the deflection due to the difference in magnetiza-
tion of a known bar and of a test bar is taken.
The BaltUtic method is most frequently used for laboratory tests, and for
sQch cases as require considerable accuracy in the results, lliere are really
two ballistic methods, the Bina method and the lAvided-bar method.
In either of these methods tne ballistic galvanometer is used for measur-
iitg the currents induced in a test coil, by reversing the exciting current, or
cutting the lines of force.
Miac- SKethod. — The following cut shows the arrangement of instru-
B«ntnor this test, as used by Prof. Rowland. Tlie ring is made of the
nmple of iron which is to undergo test, and is uniformly wound with the
BALLISTie
GALVANOMCTBII
•wrrcH
9iGk 3. Connections for the Ring Method.
cxdting eoll or circnit, and a small exploring coil is wound over the excit-
ing coif at one point, as shown. The terminals of the latter are connected
to the ballistic galvanometer.
92
MAGNETIC PBOPEBTIES OF IRON.
The method of making a test U as follows : —
The resistance, R, is adjusted to give the highest amotmt of ezeitlns eiu>
rent. The reversing switch is then oommutatod several times with the sal>
vanometer disconnected. After connecting the galvanometer Che Bwit<£ is
suddenly reversed, and the throw of the galvanometer, due to the reversal
of the oirection of magnetic lines, is recorded. The resistance, R, is then
adjusted for a somewhat smaller current, which is again reversed, and the
galvanometer throw again recorded. The test is carried on with rarious
exciting currents of any desired magnitude. In every case the exciting cur-
rent and the corresponding throw of the galvanometer are noted and
recorded.
If « = amperes flowing in the exciting coil,
n. = number of turns of wire in exciting coil,
/ = length in centimetres of the mean circumference of the ring,
then the magnetizing force
If
3fC=^X^orl.2B7xY.
l'^ = length of the ring in incheSt then
If
wC — '^wO X -p?'
9 = the throw of the galvanometer,
K=. constant of the galvanometer,
R r= resistance of the test coil and circuit,
94 = number of turns in the test coil,
a = area of cross-section of the ring in centimetres, then
(B=
2 an.
To determine K^ the constant of the galvanometer, discharge a condenser
of known capacity, which has been charged to a known volume, through it,
and take the reading «S then
•
If c = capacity of the condenser in microfarads,
e = volts pressure to which the condenser is charged,
then the quantity passing through the galvanometer upon discharge in
coulomb. 1. Q= p^.
and the galvanometer constant
c e
jr=
1.000,000 0^'
IHTid«d-Bar Bletliod. — As It is often inconvenient or impossible to
obtain samples in the form of
a ring, and still more incon-
venient to wind the coils on it,
Hopkinson devised the di-
vided-bar method, in which
the sample is a long rod h'^
diameter, inserted in closely
fitting holes in a heavy
wrought iron yoke, as shown
in Fig. 3.
In the cut the exciting colls
are in two parts, and receive
current from the battery and
through the ammeter, resist-
ance, and reversing switch,
as shown.
AMMrrt*
HanoCe
coiu {_\ oon.
ynt^oKAiiXMOiM
tKLLMTIO
Fio. 3. Arrangement for Hopkinson s di-
vided-bar method of measuring permea-
The test bar is divided near the centre at the point indicated in 5® ^'l*:
and a small light test coil is placed over it, and so arranged with springs as
HAONETIC TEST HSTHODS.
93
Id be thitrvn dear ont of flie Toke when released by polling out the looM
Old of the test bar by the handle Bhown.
In opeimtion, the exciting current la adjosted by the reeletance R, the teat
bar tnddenly pulled out by the handle, thua releasing the test coil and pro-
doeing a throw of the galranometer. As the current is not reTorsed, the
ladieed pressure is due to Jf only, and the equation for (Ria
3C
IV RK9
«4
, and
ffiX^* = l.»T^*.
Whsre Z = the mean length of the teat rod as shown in tha out
In uring the diyided-bar method, a correction must be made, for the rea-
foa that the test coil is much larger than the test rod, and a number of
Bnes of force pass through the coil that do not through the rod. This oor^
reetion can easily be determined by taking a reading with a wooden test
rod in place of the metal one.
An examination of the cut will show that the bar and yoke can also be
' for the method of rerersals. . .
■«tlc teiusre Hetk^d. — G. F. C. Searle iJourwd I. B. B.,
er, 1904), nas suggested another method of avoiding the use of the
RowiuKi ring arrangement. The apparatus consists of a square, with strips
hid oveiiapping at the edges. To obtain accurate results, the dimensions
of the square must be large, as compared with the width of the strips. The
Mine is true, but in a somewhat less degree, with the Rowland ring.
Anording to A. Press, when the relative dimensions are correctly adjusted
the ballistic galvanometer will give repeatable results, if the iron be first
effeetivdy demagnetised by means of an alternating current gradually
redaoed to sero, and then subjected to a series of reversals, from oO to 200
vitk normal magnetising current, before actual readings are taken.
(
The following eut shows tbe method with suiBcient clearness. A heavy
yoke of wrought iron has a small hole in one end through which the test
rod is pushed, through the exciting coll
shown, and against the bottom of the
yoke, which is surfaced true and smooth,
as is the end of the test rod.
In operation, the exciting current is ad-
lusted by the resistance R^ and the spring
baUmce is then pulled until the sample or
test rod separates from the yoke, at which
time the pull in pounds necessary to pull
them apart is r6ad. Then
(B=: 1,317 X
•Ji
+JC-
Where P = pull in pounds as shown on
the balance,
A = area of contact of the rod
and yoke in square inches.
JC" found as in the Uopkinson method
preceding this.
Following is a description of a practical adaptation of the permeam«for to
ibop-work as used in the factory of the Westinghouse Electric and Manu-
fietaringCo. at Pittsburgh, Pa.
8. P. Thompson'! per-
meameter.
94 MAGNETIC PROPERTIES OF IRON.
She PemteaBietcr, as med by the 1Ve«tl«fffti4»««« Klectric
ntfCT. Co.
Dbbiok akd Dbbcriptiok prepared by Mr. G. E. Skihiter.
A method of meaiurine the permeability of iron and steel known as tl&e
" Permeameter Method *^was devised by Prof. SilTanns P. Thompson, and is
based on the law of traction as enunciated by Clerk Maxwell. According to
this law the pnll required to break any number of lines of force yaries as tbe
so uare of the number of lines broken. (A complete discussion of the theory
of the permeameter, with the deriyation of the proper formula for calculatinf
the results from the measurements will be found in the " Electro Magnet,^
by Prof. S. P. Thompson.)
A permeameter which has been In use for seyeral yean in the laboratory
of the Westinghouse Electric and Manufactiu-ing Company, and which bas
given excellent satisfaction, Is shown in Figs. 5 and 6. The yoke, A^
congists of a piece of soft iron 7" x 8)" x 2}'', with a rectangular open-
ing in the center 2^" x 4''. The sample, X, to be tested is f ' in diATn.
eter and 71'^ lonjl; and Is introduced Into the opening through a |'^ hole in th»
iroke, as shown m the drawing. The test sample is flnished very accurately to
f^ in diameter, so that it makes a very close fit in the hole in the yoke. Tlia
ower end of the opening in the yoke and the lower end of the sample are
accurately faced so as to make a perfect joint. The upper end of the saia-
ple is tapped to receive a i'^ screw j" long, twenty threads per inch, by
means of which a spring balance is attached to it. The magnetizing coil. C,
is wound on a brass spool, 5, 4/' long, with the end flanges turned up so that
it may be fastened to the yoke by means of the screws. The axis of the coil
coincides with the axis of the yoke and opening. The coil has flexible leads,
which allow it to be easilv removed trom the opening for the inspection of
the surface where contact is made between the yoke and the test sample.
The spring balance, F^ is suspended from an angle iron fastened to uie up-
right rack, /, which engages with the pinion, «/. The balance is suspended
exactly over the centre of the yoke through which the sample passes, to
avoid any side pull. A spring buffer, K, is provided, which allows perfectly
free movement of the link holding the sample for a distance of about 4'%
and then takes up the jar consequent upon the sudden release of the samiue.
The frame, £, which supports the pullluff mechanism, is made of brass, and
has feet cast at the bottom, by means of which the complete apparatus Is
fastened to the table. Two spring balances are provided, one reading to 30
lbs. and the other to 100 lbs. These spring balances are of special construc-
tion, having comparatively Ions scales. (They were originally made self-
registering ; but this was found unnecessary, as a reading could be taken
with greater rapidity and with sufficient accuracy without the self-r^ster-
reeling the readings. With a sample |^' in diameter, or } of a square inch
area cross-section, the maximum pull required for cast iron is about 25 lbs.,
and for mild cast steel about 70 lbs.
With the number of turns on the coil given above, the current required
for obtaining a magnetizing force of JC= 300, is about 12.6 amperes. This
is as high a value as is ever necessary in ordinary work. For furnishing the
current a storage battery Is ordinarily used, and the variations maoe by
means of a lamp board which has in addition a sliding resistance, so that
variations of about .01 ampere may be obtained over the full range of cur-
rent from 0.1 ampere to 12.5 amperes.
The operation of the permeameter is as follows : -—
The sample to be tested is flrst demagnetized by introducing it into the
field of an electro-magnet with a wire core, through which an alternating
current is passing, ana gradually removing it from the field of this electro-
magnet. The sample is then introduced into the opening in the yoke, care
being taken to see that it can move without friction. Measurements are
taken with the smallest current to be used first, gradually increasing
to the highest value desired. In no case should a reading be taken with a
current of less value than has been reached with the sample In position,
unless the sample is thoroughly demagnetized again before reading is taken.
It is usually most convenient to make each successive adjustment of cur-
THE PERU E A METER,
nat with the umple out ot poalttoD, then Istradnoa Iha umpls uid glre It
■ hiirnni.to ln>nr«|ierr«ct contact belwaenlheumpUsiidtbeToke. Ths
ml^t lotrodDCt nrlon* eitott Id Ibe mauureniantg. Tbe pull it made by
' 'If the plnkui elowlf bjr m««w of a hiuulle, E, cu-efull]' Dotlug uacL
^
■ PMloB o( the Indei of the upring helmnce u It adTUicsa oTer the bci
•M BoUng the polnl of reieue. The niMn of three or fi.ur readliig.
?«*Ul teCen u the correoted Tslue tor pull, the correiit In the cuil renm
}
UAONBTIC PBOPBKTIB8 OP JBOK.
The mugnstlilBg force JC = -737-
Vb«reni = nnmb«ro( tonu lo Ihe mignsUiing coll = 123,
f = lenfth of iDiuneUc eircalt Id oenllmeterm, mUib
SobMltDtlng the kuovu ikliut In the aboie formala we hare
3C = 13^i-
The number of 11d« of force per iqu«
./? +
Where p^puU In lh«.
^=;BreH of tlio sample In aqunre lnch«=0,306>.
JC = ''alueof [he migDetlilng force for the slTen poll.
THE PBRMEAMETEB. 97
Substituting the Talue of ^ in the aboTe formnlA we hATe
(B = 2,380 Vp + 3e
Tliere are aerend sources of error in measurements made hj the permear
meter which should be carefully considered, and eliminated as far as possible.
a. The unaToidable air gap between tbe sample and the yoke where it
paaies throosh the hole in the upper part of the yoke, together with the
more or less Imperfect contact at the lower end of tne sample, increases the
magnetic reluctance and introduces errors for which it is impossible to make
due allowance. By careful manipulation, however, these can be reduced
to a minimum, and be made practically constant.
h. As the magnetisation becomes greater the leakage at the lower end of
the lample increases more rapidly; and there .is considerable error at yery
bigh values from this source, as toe leakage lines are not broken with the
reit.
c. Errors In the calibration and reading of the spring balance. None
Imt the best quality of spring balance should be used, and the average of
icveral readlnn taken with the current remaining perfectly constant for
«Bch point on the (B'JC curve. As the square root of the pull is taken* the
errofs due to reading the spring balance make a larger and larger percient-
age error in (g as P approaches sero, thus preventing accurate deterxn^iu*-
tioiu being made at the beginning of the curve.
From the above it will he seen that the pcrmea meter is not weU adapted
for siving the abaolute values of the ouaUty of iron and steel, but is especially
•mtable lor comparative values, such as are noted in ordinary work, where
* '^Tf number of samples are to be quickhr measured. A complete curve
esn be taken and plotted in ten minutes. By suitable comparison of known
wnples measured by more accurate methods, the permeameter readings may
be evaluated to a sufficient degree for use in the calculations of dynamo
ciactne machinery.
liryedftlc's Permseameter.
Tliis instnunent is designed to enable one to test the magnetic quality
m^iron or steel magnet castings and forgings under commercial conditions,
by dnOine it vrith a special drill. A testing plug is inserted in the hole
tluM drilled and the magnetization or permeaDility is then directly mens-
It —
— - ^— =A.
1"
r.
*l m^m ■
>g ' - — - 1
Fig. 7.
ond on an instoument attached, without any calculations, by mmply
tiuoiniig over a reversing switch.
Fig. 7 shows the special form of drill employed. It has four cutting
ekes at the lower ena, which cut a cylindrical hole in the specimen. The
<lnll ia, however, made hollow, so that a thin rod or pin of the material is
Wt atancting in the center of the hole, as shown in Fig. 8, which shows a
caat steel pole piece, and some small specimens of iron and steel actually
(billed. In adaition, cutting edges are provided at the top of the drill,
vhieh cive a conical shape to the top of the hole drilled. The hole is
About f in. deep and ^ in. in its laig<»t diameter, while the pin is ^ in. in
hamster. Such a hole may be drilled in any position where a bolt hole is
afterwards to be made in the back of a pole piece, or face of a joint, or
otherwise in projections left specially for the purpose, which may be cut
off the Tasting or forging on delivery and sent to the test room.
MAGNETIC PK0PEBT1E8 OF IRON.
*^.
/
Fio. a Bpsnmacis Showing Hoii
id tha iMtiiif plug. Fig. S
. .._li'i?uii«o"
Ihs Bids* yield slightly and grip the f
pus through the pin into the plug, KDd
thence round tho muB of the mel«i to ths
pin M»in. u .hewn in Fig. ». The pi» it
nugnetiBd by current in > coil wound
is tested by use of a second or »»rch coil.
lines of force pKasina through the search
lo the cb..«e m the mvetiHtion ol tb.
CMtllE MM»»WM.
Thse result trom Hytmti* and Eddy F
a.O,
Section t
rough Plug
uidSpeoin
Profensor Ewing has given the name
causes the bigaing o7 the inducfum behind th
ma*
heating o( the iron. 11 ineruses in direct p
tevflnali. and acoording to Steinnisti. u the I.
tI
it'-lsr
number of
value ot Che induction in the iron cots. The h
nl pro<lucRi has
to be diMi-
nted either by radialian or conduction, or by
following torinula lor hysletesis loss in ergs
per cycle; h-^ (B— ''. where n - a consuin
botfi.
*r cu
ic centime
t^.'^i^
nding upc
n the kind
of iron. Taking not .002 and reducing to Engl
per cubic inch d? mstAvl Px will bo. ft - lOJ
OS-
V10-*.
n which/-
OO&B LOSS.
99
It is to be oLsaveJ that, in praotioe. oonsidemble variations in the mag-
netie density take place in parts where the macnetomotive force is a con-
stant, due to the dinerenoes in the lengths of the lines of flux. Tiiis will not
only affeot the measured hysteresis losses, but the eddy currents as well.
For this reason, machines of geometrically different form will not obey
quite the same law of loeses. Considerable question has been raised
rsffutiing the constancy of the hysteresis index. According to A. Press,
the experiments of Mordey and Hansard with transformer iron imply that
the hysteresis index for the range taken should be at least 2. Lancelot
Wildkave the index as 2.7 for densities varying from (B — 200 to 0^-400,
W. E. Sumpner states that the index varies 1.47d to 2.7, depending
upon the range of the density, and Prof. Ewing gives the index as varying
from 1.9 to 2 with densities (R - 200 to (B - 500. depending upon the
Hjatsreilc Cwuitmmtm for IMirercmt Haterlala.
Matbrial.
Htstbretic Conbtant.
1.
Beet annealed transformer sheet metal . .
Very soft iron wire
.001
.002
Thin good sheet iron
.003
Th«»k"'Bh4«t iron . x . . ,
.0033
Moit ordinary sheet iron
Tnosformer cores
.004
.003
Soft annealed oast steel
.008
^oh machine steel
.0094
Gutsteel
.012
Ckstiran
.016
Widened cast steel
.025
Hjraterciala I*o«a Factors.
(B^
®— .»••
i»(B,^i..
in Gausses.
i|- 0.002
11-0.003
11-0.004
1.000
63,100
126
189
252
2,000
191.300
382
573
765
3.000
365.900
731
1,096
1.463
4,000
580.000
1.160
1,740
2,320
5,000
828,800
1,667
2.486
3,315
6,000
1,111,000
2,222
3.333
4.444
7.000
1,420,000
2.840
4,260
5,680
8,000
1.758,000
3,516
5,274
7,032
9.000
2,122.000
4.244
6.366
8,488
10.000
2.511,000
5.022
7,533
10,044
Eddy Currenia are the local currents in the iron core caused by the E.M.F/s
CQccsted by moving the cores in the field, and increase as the square of the
mmber of revolutions per second. The cure is to divide or laminate the
on so that currents cannot flow. These cturents cause heating, and unless
tbc eore be laminated to a c^eat degree are apt to heat the armature core so
moefa as to char the insulation of its windings.
Wieoer gives tables showing the losses by Hysteresis and Eddy currents
ft one cycle per second, under different conditions. These are changed
>Bto any number of cycles by direct proportion. The formula for eddy
cvrentloss is:
p» - 42 (B"2 ff* 10-",
ia wfaidi P* — watts per cu. in., O&mm'' — maximum value of the magnetic
deaaty per sq. in., t — thickness of plate in mils, and/ —frequency.
HAOHETtO FBOPEKTIBS OP IRON.
Kraterala Vacton tor I
ATtBDIBMPATEDiT*
I'-U
WA™D«,PATn.AT*
FiiEQDBNcr or One
p;
COHFLKTE MAONmc
CoHPLKTE HjuiNenr
Ctcle m Second.
Hi
Ctcl. rn Bko«d,
■ .002
ir- .003
III
*- .002
^- .003
Per
Per
P«
Pbt
Per
Per
P<r
~
cu. ft.
r„. ft.
lb.
OTlT
1.069
0023
ae.ooo
iTeT
.0305
22.02
.04SS
2.055
!0041
67,000
,0313
52
-0045
3.24
.0068
68,000
I .3S
0064
!0S06
0137
7i:000
1 :5o
21
75
OOM
1 .87
0159
74:000
;0388
2(
41
0111
7.B8
75,000
1 .»»
.0378
26
BS
!06M
.0G7a
8!73
77I000
.osss
0128
B.12
018B
781000
I :is
:0400
78
.0000
1 .58
0204
8o;000
0416
90
.0624
0142
0.31
81,000
»:37
0424
S5
oe3«
ous
0048
S3i000
0440
ooao
0160
lisi
0240 ,■
84,000
aiieo
0448
12
40
0672
016a
1.93
ai.OOO
ii.as
»2
98
06S«
017S
2^80
0267
s7;ooo
0711
0184
3.22
88,000
13.28
0483
34
87
0724
(5
01M
4] 10
90,000
0202
0303
81,000
4:si
OSIO
ta
78
0765
37
077S
0214
.'i:46
B3'wo
^:4i
3S
0221
5.S7
0332
B4.000.
r5.88
0538
38
0548
3B
45
\0
26
0242
7!40
0363
97i00O
27! 30
7.91
0374
B8:000
27.73
0578
«.1B
0588
12
28
0883
0263
looiooo
85
0808
0270
b:42
0405
105.000
fliSO
29
0005
110.000
33.20
0694
80
1041
5.70
0746
53
55
me
0291
20.96
0786
;7
30
1194
0208
21.47
0447
ISoioOO 40.83
25
1276
CORE LOBS. ;l{)-l
Thm fttei^l»yftt«p Bletliod of Kjflter«ato Test.
The samples for hysteresis tests, being generally of sheet iron, are made
in the form of annniar disks whose inner diameters are not less than % of
their external diameter. A number of these disks are stacked on top of
eaeh other, and the composite ring is wound with one layer of wire form-
ing the magnetizing coil of n, turns. This ooil is eonneotod through a re-
Teraiog switch to an ammeter in series with an adjustable resistance, and a
storage battery. A secondary test ooil of 94 turns is connected with a bal-
Ustle galTanometer, as shown in Fig. 10.
MLLirne
QALVANOMCTCR
STOKAQC'.
■Revcmma
SWITCH
Pig. 10.
lb make the test, adjust the resistance for the maximum exciting current.
BererM the switch several times, the galvanometer being disconnected.
Thsn connect the galvanometer, and reduce the current by moving the con-
tact arm of the rheostat up one step. This rheostat must oe so constructed
that an alteration in resistance can be made iHtkout opening the circuit even
for an ieHstant. Note the throw in the galvanometer corresponding to the
diange in exciting current. Follow this method by ohangin|[ resistance
ite^-by-step until the current reaches zero. Reverse the direction, and in-
ensse step-by-step up to a maximum and then back again to zero. Reverse
oaee more, and increase step-by-step to the original maximum. In every
cue note sund record the value of the exciting current i, and the corre-
iponding throw of the galvanometer, B, Form a table having the following
fcwidingi to its columns : —
<, JCi •. change of (B, (R.
TalUfW of S9xe obtained from the formula,
3C = T^*i when I = average circumference of the test ring.
Change of (Bis obtained by the formula,
- la^R KB
vhereall letters have the same significance as in the formula on page 92.
Bemember that we started in our test with a maximum unknown value of (g.
■ad Uiat we gradually decreased this by steps measurable by the throw of
the galvanometer, and that we afterwards raised the (Bin an opposite direc-
tip& tothe same maximum unknown value, and still further r^uced this to
zero, and after commutation produced the original maximum value. Ac-
eording to this, if due consideration be paid to the sign of the (B which is
determined by the direction of the fralvanometer throw, the algebraic
ram of the changes in (B should be equju to zero ; the algebraic sum of the
int or second half of the changes in (B should be equal to twice the value
aeuTe of JC^^<1(B' ^^® ^^^ enclosed represents the energy lost In carry>
ing the sample through one cycle of magnetization between the maximum
liniti -f-(Bftnd — (B- Measure this area, and express it in the same units as
ii employed for the co-ordinate axes of the curve. This area divided by 4ir
102
MAGNETIC PROPERTIES OF IRON.
gires the number of eras of work performed per circle upon one cubic c«:&ti-
meter of the iron, the mduction being carried to the limits -f- (E<uid '— (B-
V^e WattBi«f«r Method of HyvtemMs Testa.
Inaemuch as the iron, a sample of which is submitted for test, is generally
to be employed in the manufacture of alternating-current apparatus, it &
desirable to make the test as nearly as possible under working conditions.
If the samples be disks, as in the previous method, and these m shellacked
on both sides before being unitea into the composite test^ing in order to
avoid as much as possible foucault current losses, the test can be quickly
made according to the method outlined in the following diagram :
ALTERNAT
Fig. II. Wattmeter Test for Hs^teretic Constant.
Altematins: current of / cycles per second is sent through the test-nns.
Its voltage, E, and current strength, i, are measured by the aitematins-
current voltmeter, Y , and ammeter, A. If r be the resistance of the test-
ring coil of »i turns, then the watts lost in hysteresis W, is equal to the
wattmeter reaaiug fl^' — ih'. II the volume of the Iron be T cubic centl*
meters, and the cross section of the iron ring be a square centimeters, then
Steinmetz's hysteretic constant
71 =
Vf\ E\»
i.«
Foucault current losses are neglected in this
formula, and the assumption is made that the
current is sinusoidal.
Swliisr*s Hysteresis Tester. — In this lu-
strum en c, Fig. 12, the test sample is made up of
about seven peces of sheet iron \*' wide and y*
long. These are rotated between the poles of a
permanent magnet mounted on knife edges.
The magnet carries a pointei which moves
over a scale. Two standards of known hyster-
esis properties are used for reference. The de-
flections corresponding to these samples are
plotted as a function of their hysteresis losses,
and a line joining the two points thus found is
referred to in subsequent tests, this line show-
ing the relation existing between deflection and
hysteresis loss. The deflections are practically
the same, with a great variation in the thick-
ness of tne pile of test-pieces, so that no cor-
rection has to be made for such variation. This
instrument has the advantage of using easily
prepared test samples.
Feo. 12.
Hysteresis Uteter, ITsed by General Klectric Co.
Designed and Described by Fbaxk Holden.
During the last few weeks of the year 1892 there was built at the works of
the General Electric Company, in Lynn, Mass., under the writer's direction,
an Instrument, shown in Fig. 13, by which the losses in sheet iron were
determined by measuring the torque produced on the iron, which was
punched in rings, when placed between tne poles of a rotating electro-mag-
net. The rings were held by a fibre frame so as to be concentric wiUi »
a«A«d m pointer, with
■ bilicsl (prluK roMM
Bd tbM nhflu Oia Tul
top pvt o' thU iiH
■ tbln brua STUti-
.Dg WM put in plkG«, the
Ina ensued wltb the tbktt,
tlv rotated with the ringa. A
»1tb the lower end of thsapilng
aero of the degree acale when
'■■ readv for na*. By tlilj ai-
m found what diilortioQ It «M
1 t^b *'
le rlua, mad*
>trioailT oppc^
ivolied with > masnet.
,„ ig agalnat whioh ruhbed
Joined through a geiialtlTa Weaton
.. .1, II . right anglea to the
i
__ _ cnit being negllglWe,
manTalDeotthecurrentia theelrcolt was proportroral to the
Unaih the coll. Knowlngthe gonatant of (hn volimeter, ihedoflectlon wai
tadlT ealeniated from the ipaed of the magnet, the number of lurn> fn the
«il. Moanecti ■ -* -*■ ' "•- "'-"■ ■'* ""■"■ •"
■dnetiun ol 2,1
MWgaiiai
le Bhaf t :
ounUng. the deQectloni
nh U« daalred Inducllo
^e of tl
aea, tbe 1<
iBIerior apace of the ringi wM iK«Hglble.
Carriwl on tbe >ha« below the msgnet wa« a pnllay aro
8* wiull be found by obaerTlng that
to be produced on tbe Toltmeten
I In the rings, were flnt calculati
104 HAGNETIC PROPBKTIES OF IBOIf.
rvTolntloaa par mlnnte vu genarallj udoptod u the ipseil In thb aaso.
Ttis molor being run at the dHlrsd gpeed, Cbe magnetliliiE onrrant iru mA-
Ctted until the caloulHteddaH action vu produced^ou tbe vDltmaUir. KMp-
t tbc magnaticlng aurreutoonttADt, tbe^peed waa changed aucoaaaWalj In
Talua to certain Tsluea, and the corrv«p>indlng cllglortlans of tba Bpriac
ti»c»aarT to balance tbe affect of the magnet noted. When tbla prooeaa
waa cairM out at dlffsrenl inductinn values, and tbe ergi eipundxd par
Sroduced, as ibowaln Fin. 1* and IG. It waa found tbat tbe ilope of itao
nee decreaaed veij rapldlf wltb tbe deoreaee In tbiokneea of (he Irun aheet
uaed ao u to Indicate tbat had it been cbln euougb ibe ilope would tuiT«
been lero between 100 aod SOO revalutlons per mlnule, which wag abuat ths
higbeat speed penniaalble. From tbii It would eeBni ibat. In these taeta, th«
total loBB per c^cle bad two componenla ; one remaining canatant, due to
hyatereala, and [be other larylng ae tbe gpeed it tbe magnate, due to anr-
Fla. ISglrea obeervatloni oleddjcuneut loMand thlckneea of iron aheet
on this aaamnpUon. Tbe line drawn la a Mrabola, ao tbat II would appeu-
ranee of obaer
•aid thaatieet
Fig. 11 glTea Unea troi
taken lower
the Unea , ,„ ^ _ — „,
read with tbe tacbometer arallable for tbli partkuliLr teal. Plotting the
hntereala ae a function of the lndu(;(bm. In (his caae tbe polnta are all qolt*
otoaa to a curve wbuae equation la, Krgn = A constant X (Uenalty peraquarB
caatlmeter)'", three points In the Utter cnlculHted curre beliig ahown by
tblck. and ibowa a greater eddy current loss. Tbe equation for the byitere-
sle curve tor tbla aaniple la, Hrgn ^ A constant x (Density per square oenti-
melera)'-', some points In the laller curve being shown bycrosees.aa before.
the Induction In Fig. IT. The cunw dr:iB n are paraliolas; ahowJng that In
Induction, altboQgb there were often greater varlatli>ns from tbat law than
these two samples abow. The average exponent tor tbe hyatereala cnrrea
was a little over 1.5, although It varied Irom t.4 to I.T. Sings tested In tbla
ftep-by-atap method. There were dtscrepanclee of n« much as 4 per cent be-
tween the two resalle, but an average it ten teeCB ahowed the balllstlc^il-
Tanometer method gave results 2.6 per cent lower than the other. Tbia
difference la eaailv attributable to eiperlraental errors.
It being noticed that for a given indactlon In the rings, the masnetlalag
eurrenta for dlffeient aamplea did Dot vat; much, it waa planned shortly
lEM eompIaUng tb« mboie tppuatu* t.
■hiebwoDktnM«leetTO-iiiagneU ot ■nchhlghTelucti^.- .--..
ofUieringewoiildb«negllgtbl*,»iiiili»lo«on
._„_, be d«nii3eD( only on Uie cuirent fly maliln •
^^^^BBM^DBn^ Uis electio-inuDeta ot soluble Iron uin ot
I Ifa^r 1 rtK,nt«i»-tWrftli8croM-«Kilono[ tberlLji
*^^^^S»S^^** uHHl. the Iron muj be no LlgbU wtumled
ts^_^ UMt tbs Induction *iLl ™m^Qqiiile coi..liiiit
Pio. H. Hodlfled Hy>l«r- under eoiiHlderable Tarlnlion In "^ ";»8""-
«i, Meier. !^J«„™"£, co "p.tToS! "^ r«J"e^z?nl
oorronti, imd the f Inra can be at ■boat their
mulBiiiin penneBbllltT irhen tboi msgnatlied. Such an laatruroeht 1*
item in Ft la ill luioriglntil eiperlmental Iorni,»^th the rinm In potlHon
nd) tor ^1. A oiotRaed form i. shown In Kg. IB. Tie ring, are
Iwn. .llo«ed to rotate In opposition to Ibe action ot H^priag and tarry ft
pranter oxer a scale, so that II In qnlte direct reading. Twenty^vo oompar-
i
koM of this [Ditrainent irlth the original one gare reanlti that >cre*d
■tihlD a per cent In all caeca, and more than half were within 2 per cent of
•fnwnent. Permanent mBgnela had been preTlouilj tried, but the attempt
Koud to (how (bat tho Inatrnment would not, In that caae, compare sam-
plci ol Iron vldelT different In character ; and tbe writer not being able to
Fio. IS.
the taj attention to tbe matter, no further lnTe«llgatlonj la that direction
Ttic inatrumeni tint deacribed has been In use contlDuonily alnco itii com-
(latlon at the worke of the Oenatal Electric Company, In Schenectady.
106
MAGNETIC PROPERTIES OF IRON".
MI»I»ir CVlftltBllT FAOTORA
coRB DKirftnniBS a]Vi» for tarkovs
IiARXlTATIOirS.
(Wie&er.) .
o5«o
10,000
16,000
20,000
26,000
30,000
31,000
32,000
33,000
34,000
36,000
36,000
37,000
38,000
39,000
40,000
41,000
42,000
43,000
44,000
46,000
46,000
47,000
48,000
49,000
60,000
51,000
62,000
53,000
64,000
65,000
50,000
57,000
68,000
59,000
60,000
61,000
62,000
63,000
64,000
66,000
Watts dmsipatkd
PKB CUBIC FOOT OF
IBON AT A FRB-
QUEKCY OF 1 CYCLE
FEB BBCOKD.
Thickness of laminatioii,<
.010"
.020"
.040"
.0007
.003
.012
.0016
.007
.026
.0020
.012
.046
.OOtf
.018
.072
.0066
.026
.104
.0070
.028
.111
.0074
.090
.118
.0079
.032
.126
.OOM
.034
.134
.0060
.036
.142
.0094
joas
.150
.0009
.040
.158
.0104
.042
.167
.0110
.044
.176
.0116
.046
.185
.0122
.049
.194
.0128
.061
.204
.0134
.064
.214
.0140
.056
.224
.0146
.000
.234
.0153
.061
.246
.0160
.064
.266
.0167
.067
.267
.0174
.070
.278
.0181
.072
.289
.0188
.075
.300
.0196
.078
.312
.0202
.061
.324
.0210
.084
.337
.0218
.087
.349
.0226
.001
.362
.0234
.004
.375
.0242
.007
.389
.0261
.101
.403
.0260
.104
.416
.0269
.108
.430
.0278
.111
.444
.0287
.116
.458
.0296
.118
.473
.0306
.122
.486
.060"
.046
.104
.185
.288
.416
.444
.472
JS03
J69i
.567
.600
.633
.667
.703
.740
.777
.816
.855
.896
.987
.979
1.022
1.066
1.110
1.066
1.200
l.ifflo
1.297
1.346
1.397
1.446
1.500
1.666
1.610
1.666
1.720
1.776
1.833
1.891
1.961
66,000
67,000
68,000
69,000
70,000
71,000
72,000
73,000
74,000
75,000
76,000
77,000
78,000
79,000
80,000
81,000
82,000
83,000
84,000
86,000
86,000
87,000
88,000
89,000
90,000
91,000
92,000
93,000
94,000
96,000
96,000
97,000
98,000
99,000
100,000
106,000
110,000
116,000
120,000
126,000
Watts dissipatbd
per cubic foot of
tbov at a krb>
quevcy of 1 cyci<b
pb& second.
Thickness of lamination, S
.010"
.0316
.0325
.0336
.0345
.0366
.0366
.0375
.9386
.0396
.0407
.0418
.0429
.0440
.0451
.0462
.0474
.0486
.0498
.0510
.0623
.0535
.0648
.0660
.0673
.0686
.0699
.0612
.0625
.0638
.0661
.0666
.0679
.0693
.0707
.0722
.0797
.0675
.0056
.1040
.1128
.020"
.040"
.126
.503
.130
.519
.134
.634
.138
£60
.142
.566
.146
£82
.150
JBOB
.154
.616
.158
.633
.163
.660
.167
.668
.171
.686
.176
.708
.180
.721
.186
.740
.190
.758
.194
.777
.199
.796
.204
.815
.209
.836
.214
.866
.219
.876
.224
.896
.229
.916
.234
.937
.240
.968
.245
.979
.250
1.000
.266
1.021
.261
1.043
.266
1.064
272
1.066
.277
1.109
.283
1.132
.289
1.156
.319
1.274
.360
1.396
.382
1.528
.416
1.664
.451
1.806
.080"
2.013
2.076
2.187
2.200
2.285
2.380
2.386
2.483
2JB»
2.800
2.870
2.740
2.810
2.888
2.968
3.038
3.108
3.184
8.280
8.840
3.420
3JS00
3JM0
3.682
3.746
3.880
3.915
4.000
4.085
4.170
4.257
4.345
4.436
4.528
4.622
5.006
6.598
6.113
6.6S5
7.28S
ELECTROMAGNETS.
PIftOPfiJRTlES Ol*.
RXYISJCD BY TOWVBKSD WOLCOTT AJXD PbOF. SAMURL SHKLDOX.
Reaidtuil MctoneHtm is the ma^etieation remaining in a piece of mag-
netic material after the magnetiniu; force is discontinued.
RetenHveness is that property oi magnetiaable materials which is mnns
ured by the residual magnetism.
Coercive Force is the magnetising force neoessary to remove all reeidual
magnetism.
PermaTient maoneHam is residual magnetism in a material of creat coer-
cive force, as hard steel, which has little retentiveness; while soft iron has
great retentiveness but little coercive force.
The following paragraphs are condensed from 8. P. Thompson's "The
Electromagnet : '*
Hagm^to-MottT* force. — The magneto-motive force, or magnetl*-
liig power of an electro-magnet Ia proportional to the number of turns of
wire and the amperes of current flowing through them ; that is, one ampere
flowing through ten coils or turns will produce the samema^iMtoHBiotive/wvf
aa ten amperes flowing through one coil or turn.
If n == ja umber of turns In the coll,
/= amperes of current flowing,
1.267 = ^ (to reduce to C. G. S. units).
Magneto-motive force = 1.257 x n/= ^.
Xtki/^nalitj of REacnotlc Force. — Intensity of magnetic foroe in aa
electro-magnet varies In different parts of the magnet, being strongest in
the middle of the coil, and weaker toward the ends. In a long electro-mag-
net, say a length 100 times the diameter, the intensity of magnetic force wiu
be found nearly uuiform along the axis, falling off rapidly close to the ends.
In a long magnet, such as described above, and in an annular ring wound
evenlv over ite full length, the value of the magnetic foroe, JC* >* deter-
mined by the following expression :—
3C== 1-257 —r- , in which {= centimeters.
If the length la given in inches, then
5C.= .496-^ , in which l,,^ Inches.
If intensity of the magnetic force is to be expressed in lines, per sq. ln<^
JC/,= 3.198 x^.
Valve of JC ^^ <^« centre of a Mncle-tiini of Coaductor.—
In a single ring or turn of wire of radius r, carrying / amperes of current
3C= I X ^= .6284 X ^
-Force on Conductor (cnrrjl nir cnrrent)
In n mnynetlc Field. — A conductor carrying
current in a magnetic field \» repelled from the
fleld Dv a certain mechanical force acting at right
angles Doth to the conductor itself and to the lines
of force in the field ; see Fig. 1.
The magnitude of this repelling force is deter-
mined as follows, assuming the field to be uniform :
ft
JP =r magnetizing force, or intensity of the fleld.
I = length of conductor across the field in cm.
I,. = ditto in inches.
/ =r amperes of current flowing in the conductor.
F r= repelling force.
:=3^i/. Jf in dynes =?^"'^'/
10 ^ 25.4
F in dynes = "^^^ • F in dynes = 5^^;; j' -' . ^ in grains =
Fio.l. Action of Mag-
netic Field, on Ckm-
duotor carrying cur-
rent.
UV// »// /
16146 ■
108
PBOPEBTIBS OF ELECTROMAGNETS. 109
'mriL 4Lmm9 lajr GoBdvcior (e^rwyiw^p Cnnreat) te aioviaf
acroas m Magmetlc field.
If the conductor described In the preceding paragraph be mored acroM
the Held of force, the iiik>rk done will oe determined as lollows : in addition
to tbe symbols there used, let b = breadth of field in and acroM which the
ecmdnetor is moTed ; «o ^ work done in ergs.
5/ =: area of field,
If=blx^ = number of lines of force cut,
of Comlvctor (oarrTin^ carrent) »ro«ad a V/Lmffn^t
Pole.
If a eondnctor (carrying current) be so arranged that it can rotate about
Ob pole of a mamet, the force producing the rotation, called torgtu, will be
aeterniined as f^lows : The whole number of lines of force radiating firom
the pole will be 4 v times the pole strength m.
DlTidlng by the angle 2v, the torque^ T, is
T Z^ "Tn" —- '2 flu,
Xverif eleetrie efrcuii tends to place itself so as to embrace the masckmim
TWo eieetric oonduciors caarryina cwrraUs tend to place themselves in poeitkm
"'' that their mutual flux may oe mctxvmum ; otherwise stated : if two cur-
I ran parallel and in the same direction, each produces a field of its
own, and each conductor tends to more across the other's field.
In two coils or conductors lying parallel to each other, as in a tangent gal-
ranometer, the mutual force vanes directly in proportion to the product of
their req>ectire n/,and inversely as the axial distance they are apart.
PrlBCi|»le or «!■• IHofvetlc Circuit. —The resistance that a mag-
netie circuit offers to the nassage or flow of magneiie lines of force or fiux^
has been given the name of reluctance^ symbol (^, and Is analogous to resist-
mneej to the flow of electric current in a conductor.
The magnetic Jiux or lines of force are treated as current flowing in the
flsasnetie oirenit, and denoted by the symbol ^.
The above two factors, together with thomagneto-motive force described in
the eurly part of this chapter, bear much the same relation to each other
do resistance, current, and E.M.F. of electric circuits, and are expressed
follows: —
Maimetitt flux - Magneto-motive force
" reluctance
<F=^'= 1-287 n/.
._ 1.257 n/
1.257
110 ELECTKOMAGNETS.
If dloMiudoiis are in inoh«s, and A\Bin Bqnare inches, Umb
and ^ = (B" A",
TMe Itaw of Tmctloa. — The formula for the pnll or lifting-power
of an electromagnet when the poles are in actual contaot with the arm*>
tare or keeper is as follows :
Pull (in dynes) = ^
8 IT
Pull (in grammes) = ^^^^^ •
PuU (in pounds) =^j^P^.
In inch measure: Pull (In pounds) = -^ «^ooo '
Traction.
This proportionality to the square of the induction aooounts for some
anomalous peculiarities in the way that the keeper of a magnet holds fast
to the poles. If the pole faces be perfectly true and flat and the face of
the keeper the same, the keeper U actually held with less force than wheo the
I>ole faces are very slightly convex. Or, aflnin, if the keeper be slid to one
side until only its sharp ease and that of the poles are in contact, it will be
found to adhere more firmly than when placed squarely and centrally on
the poles. In general, a magnet holds titter to a slightly uneven surfaoe
than to one which perfectly fits the poles. The reason is that, when the
area of contact is decreased, the intensity kA the induction throuf^ the
remaining contact is increased by the crowding together of the hues of
induction; and, as the traction is proportional to the product oi the area
and the square of the intensity of the induction, so long as there is sufficient
crowding of the lines so that the square of their intensity increases more
than the area is diminished, the traction is inoresised by inducing the area
of contact. ^^
The amount of the traction is usually determined by the formula, T =: ^^<
in which T is the traction per square centimeter expressed in dsmes: to
express the taaction in grammes, this ficnire is of course divided by 981, or
for pounds avoirdupois per square inch it should be divided by 60()O0.
This formula is correct tor the force required to separate the halves of a
straight bar mafcnet out in the middle, if the winding be also in halves and
these halves separate at the same time as their respective halves of the
oore and if, further, the winding fit the core closely. It is also oorreet for
the separating force when the magnetism is residual; as in the case of a pet^
manent magnet. In other oases, for example, where an ordinary keeper is
pulled away from a magnet, the formula is not strictly accurate on account
of the keeper being attracteid partiv by the core of the magnet and partly
by the current in the winding directly. However, the attraction exerted by
the coil is usually small as compared to that exerted by the core; and the
formula is not very much in error.
The attraction between the two parts of the iron is always 2 w^ dynes
per square centimeter, ^ being the intensity of magnetisation, that is the
number of units of free magnetism per square centimeter. But (gr=4 v^
+ 5C 80 when J(^ = 0, that is when there is no magnetizing force, 2 «(5a
/o«
=: ^ , which is evidently correct, as there is no attraction except between
the two parts of the iron. When JC '" "^^ equal to zero, that is, when the
magnetism is not residual, there is a force between the coil and the ]>art of
the iron that is move<l away from the coil equal to J(^, 3 fis^es per square
centimeter, so that the whole force of separation is 2 ir^* + 3C 3* "^lien
there is a coil on each part of the magnet and both parts of the magnet
PBOFBBTIES OF ELEGTKOMAOXET8.
Ill
the
the
the
the
but.
tkmbet
both ooils are just alike, there are two of these 5C0 forces, because
eofl attracts the other part of the iron; but as in this case ^ represents
intensity of the magnetising force €i the whole coil each half now
the other part of the iron with a force of ^—^ and both forces
2 T^l
equal JC5- The two eoils attract each other with a force of^
square oentimeter. so the whole force is2ir3*+3C3+ ^^. which
be written^ (l<Jw»5» +8»5C3 + 5e«)-^(4»3+3e)»-^
square centimeter, so in this case also the traction is proportional to
square of the intensity of the induction. If the eoils be loose upoo
eoras so that their areas are sensibly greater than those qt the cores.
whole force of separation is fp-eater than that aiven by the equation;
in praetieal cases, the error is usually small. ' In all eases, the attrao-
''-* the iron parts is 2 «- (P per square oentimeter.
Tr«ctl«M •f Slectr* Mm^pmmtB*
A
(ft'/
Dynes
Grammes
KllogB
Pounds
Lines per
lines per
per
per
per
per
sq. inch.
sq. em.
sq. inch.
sq. cm.
sq. cm.
sq. cm.
1,1100
6,400
30,790 «
. 40JS6
.04066
jm
2,000
12,900
169,200
162.3
.1623
2.306
9,000
19,360
368,100
366.1
.3661
6.190
4,000
2B,aoo
636,600
648.9
.6489
9.228
ffiiOOO
32,260
994,700
1,014
1.014
14.39
iJOOO
38,700
1,432.000
1,460
1.460
20.75
7J0OO
46,160
1,960,000
1,987
1.067
28.96
MOO
51,000
2,647,000
2,696
2.606
36.96
9A»
68,060
3,223,000
3,286
3.286
46.72
10,000
64,600
8,979,000
4,066
4.066
67.68
11JU»
70,160
4,816,000
4,907
4.907
69.77
13,000
77,400
6,730,000
5,841
6.841
83.07
13JD0O
83,860
6,726,000
6,866
6.866
97.47
14,000
90,300
7,800,000
7,660
7.660
113.1
15,000
96,760
8,963,000
9,1'^
9.124
129.7
lf,/00O
UttJUO
10,170,000
10,300
10.390
147.7
17/100
100,660
11,600,000
11,720
11.720
166.6
18,000
116,100
12,890,000
13,140
13.140
186.8
»JBO0
122,660
14,360,000
14,630
14.630
208.1
»,000
129,000
16,920.000
16,230
16.280
230.8
■xcitii
»srcr mrn^ TvACtlOM. — If we can assume that there is
no magnetic leakage, the exciting power may be calculated from the follow-
iqg expression; AUdtaneDSions being in inches, and th^puU in pounds:
,»7=ffi^'x.3132.
^ ~i"X.3132'
also,(B^'=8494y^
PulT
Area"
fll/=2061 X — X y •
If dimensions are in metric measure,
r=3961 -^
Area"
«/:
Pull in kilos
ji Y Area In sq. cms. '
*» T Area in sq. ins«
oi=««v's:
Pull in kilos.
Area sq. cm.
112
ELBGTR0MAQNET8.
^fmmilf « OV EJLECTl»OMA«mET0.
The method uaed by Cecil P. Poole for predetermining magnet windinn
is as follows: Temporary test ooils, of wire much larger than wiU probalMy
be required in the permanent coils, are wound to occupy the space th&t
it is estimated the permanent coil will occupy. Current ia passed throueb
the temporary coils in series with a water rheostat or finely graduated
reaiatance, by means of which the excitation may be oloeely adjusted,
llie exciting current is adjusted until the desired magnet pertormanoe is
obtained; the current producing this e£Fect is represented by /«. Tlie
current is then increased or decreased as may be required imtil the resist'
anceper foot of the winding corresponds with the resistance per foot given,
by Table I herewith, after five hours. The current required to produoe
this result is indicated bj^ Ih,
The size of wire required to produce a given nutnber of ampere-turns
under given conditions of mean length and voltage is
€P
KAtLm
in which eP equals circular mils of the wire to be used, JT is a ooeflScieiit de-
§ ending upon the specific resistance of the wire, A t equals the ampere-tums
esiredV-^ equals the mean length per turn of wire in inches, ana V equmls
the volts at the terminals of the coil. With the best commercial graoe of
magnet wire, K becomes unity at a temperature of about 140" Fanr., since
the resistance per mil-foot of the wire at that temperature is 12 ohms.
The resistances of wires given by Table I are based on this temperature.
Table II has been calculated from the foregoing formula for this temper-
ature.
From the first test made with the temporary winding the desired ampere-
turns are obtained, and from Table II the sise of wire required to give the
nearest number of ampere-tums per volt corresponding to this test and the
proposed working voltage may be obtained.
Table I. —
e« irire at \4M» Tent]
•ft.
Wire No.
Resistance per Foot.
Wire No.
Resistance p^* Foot
4
5
6
0.0002875
0.0003625
0.0004571
19
20
21
0.009316
0.01176
0.014814
7
8
9
0.00057662
0.0007268
0.0009168
22
23
24
0.018601
0.023575
0.0297
10
11
12
0.001156
0.0014575 >
0.001838
25
26
27
0.0375
0.04725
0.05956
13
14
15
0.0023175
0.002922
0.003684
28
29
30
0.0751
0.0947
0.1194
16
17
18
0.004646
0.00586
0.007389
31
32
33
0.1506
0.1899
0.2395
WINDING OF ELECTBOHAGNETS. 113
Thm number of turns of wire in the test coil will, of oourae, be known,
mod the product of thiB number and the current, /•. u the required exciting
force in uiq>ere>tums. The mean length per turn of wire in the perma-
nent minding will be the same as that in the teet winding, subject to minor
oonections that may prove necessary in rounding out the final results.
Tentatively, at least, the mean leqgth, L», will be equal to
in wfaidk Gt is the i^rih of the test coil and g the girth of the bobbin of form
in whi^ it was wound. Having the ampere-tums required, the mean
leoKtli per turn of wire and the voltage that will be applied to the terminals
of tne coil (or each coil, iJf there are more than one), the sise of wire that
inuat be used in tiM permanent winding is obtainable by the application
fd TaUe II. It may nappen that none of the mean length values in the
table will be found to correspond with that of the test winding; in that
event, the nearest talt>ie value may be adopted and the mean length per
turn of the permanent winding made to conform to this. In many cases
it will be found that both the excitation per volt and the mean length per
torn of the test winding will differ from all values in the table; in such a
ease, the nearest meanlength value in the table should be adopted which
gives the nearest excitation per volt in exeett of the desired value.
Hm table is worked out on the assumption that any two wires drawn to
B. A 8. gauge and differing in sise by ten gauge numbers will have cross-
sectiooa] areas differing in the ratio of 1 to 10.163 or 10.103 to 1, according
to which wire is considered first.
As stated in the note at the foot of the table, the amp^-e-tums per volt
in eolmnn a apply to the wire sises in line A across the top of the table:
tikc ampere-turns per volt in column b apply to the wire sixes in line B, ana
those in column e, to the wires in line C. Thus, if a coil wound with No.
S wire has a mean length of 45.11 inches per turn, its exciting force will
be 366 ampere-turns for each volt at its terminals; a coil of the same mean
lenpith 'but wound with No. 18 wire will have 36 ampere-turns per volt.
whDe a ooil of No. 28 wire with the same mean length pa- turn will yiela
oniy 3.54 ampere-turns per volt of applied E.M.F. The table is calculated
OB the basis of the wire sises in line B and the ampere-turns per volt in
eDhmm 6, henoe the latter values are not numbers from which dedmals
have been dropped, but are exact.
If the winding is to operate at constant potential, as most magnet wind-
ings do, the watts dissipated will be exactly proportional to the current
ps Sling, and this will be invers^y proportional to the length of the ooil par-
alel with the magnet core if the s:irth and temperature remain constant.
The temperature will be imchangeoTof course, the value A, of the current
seesssary to produce the working temperature having been ascertained by
trial, as previously described. If the girth of the permanent winding
cannot be made identical with that of the test winding, the correction in
dimemions will be simple. First, the proper length on the hypothesis of
anebanfed girth must be detemuned. As the temperature of the coil is
a function of the heat dissipated per unit of effective radiating surface,
and the radiating surface is approximately proportional to the length of
the ooil parallel with the core (assuming the girth fixed), the heat disn-
pated per unit of surface will be approximateiv proportional inversely to
the square of the ooil length. Therefore, if the girth of the permanent
winding were identical with that of the test windingi the proper length
of the permanent coil would be given Ky *'' equation.
IrtX /^-L. (1)
in which L* is the length of the test ooil and Le the eaiculated length of the
permanent eoil on the basis of unchanged ^rth. Table III (divided into
ibttr sections. Ilia, Illb, Ille and Hid,) ^ves the corrected ooil length,
Lc, corresponding to a considerable practical range of test coil lengths,
L^ and ratios oi /• to /*• If no correction in the mean length per turn
114
BUDOTBOHAaifETS.
t
I
0
I
1
e
B
H
k
I
i!
m
t
fl
I
fl
e
6
a
R
I
•
H
H
9
I
CO
!^
»o
»0
•*
-^
«5
CO
CO
CI
04
^$4<-i^C4 cQiooo>-«o aboot^M tviHioOtO
uQ^coci^ oa»aooor«^ oio-^'^co cio)<-«i-^c>
tOiOOOOIb-
^CO WCw06
V^Hoo'toeo
coo «D
cieooooo
2<r^eooii
^iovhoco <»t««i-4(o <S c!iooo» OtoStOO
^Jtrdsiff »-<o6Maeod ofi^'d«5co -^0050^53
oaoSoooo ootN.r«t«h- oootoio io9-9^-«
^a»^eo<D cotoScI «-4t^Sr»S ioiot<>'^oo
Ooih^Mh^ C09iOC9O> fOQiOr-^t* '^'HOQ^OCO
6lC4^^0 OS0»0»00 00Q0t«r^«O «DCO>OiO<0
o»^rH(Dt» cieococoeo uSi^oo^h- 'ifuSooooo
C4»OQQi-4iQ Q>OQ(00« 00*-*i90!0 ^l<*^Or*
cDuS^^m eoc(c9«-4*-4 oooSSoo oot^-ror^e
coooh*co-i cioS^hSo °^.^^ . <ot^eocsik5
tOQOQOad^ ^^•c^«P^ tdood'^qo c^^codtn
OOOOKt^ <OiOiO^'^ €00404^0 OOtOOOOO
CI
s^
CI
CO
vMiovHoSt^ «SSb>SrH <<iioSSdn Se^icSco
ssass sssisa ssssss sssss
•
t-4
CI
CO
40.5
38.67
36.82
35.22
33.75
32.4
31.15
30.
28.95
27.93
27.
25.31
23.82
22.5
21.31
20.26
19.28
18.41
17.61
16.87
0
s
s
rH«5<^9hS ooco^iocs ookdcooo ScommS
iiii9 ii^ii isiii iiiii
a>
s
iiiii iitiii ii^ni iiiii
»
00
s
sf:s:s^ s^sss ssijiiiii iiiis
u
t^r<*«oo« <0(p<piou2 ioio:i«-<f'« ^cocococ«
aoi-fcico '«*u5«t>.o6 o5»Meo»ii> di-<coioi^
^cJcicici cicicic4C4 cicoeocoeo co**^^-"*
iO
Sc^g^S^^ ^^^^^ UU^^^ ?^999
O^deo"*
RC4CICICI
'h' '4; ^ '
C4C4C4<
COCOCOCOCO ^^"T^^
^■B
=1
WINDINO OF ELBCTR0MA6NBTS.
116
s^^s^ ^^^,^,^ ss^ss ^^,^^^,
oc»aor»r>- <o«Dioio>o lo^^eooo cocqoc^m*
aeor^QO^ SotS^to ^QOnSS ^ot«>oM
e««^c>oie» aooot«r*o oious^^ ^^coeoeo
o<^eo94'H ooo»a»ao oot«^<D<OiO loiO'^^V
^^^^<> ^^,^^^, ^^^^,co ^^^^^.
QXr«>iO'« e09«C«^O OOkOOt^r* ««0«C>iOiQ
h--«7ao^ ^^rHeo>3 SBt^b^Okci lOo>o^^*
gn-^okoo t^cDio^eo ct^ooob Qooot-b^td
9ioo3m veo^oo e>4t«>io^Q0 oo^uSoio
nAfx-^eo •-•do»«t« <o^eQC4«H ddo»o>od
eOfiCldOt C*CiiM»Hw^ (Ir-liHt-lr^ i-Hi-H
c«<-«49l cQOot*»o ^«Dot-co ooooeot*
Qr«^^9 t-w)^c^^ OQOt^io^ eoc«e4i-td
#eoeoeQci c)clc^C4C« e5,-«^^iFS ^^^^^
SSSi«Cft 9Smi»<-4 So^udSo^ Sl^*<^^S
i-i9»dd ^oioQDt^ uam^doo r»«io^oo
to^'^mn eoeocoeic^ eIe«c«t-«.-« p^ri^»-ii-t
^C««C«4eO CO<-lMOQQ |x.*H^iA«9 •-•lQ<Da'«
-»c«5i--»<5 ^t^eo^N udOi-ioci b»w»-«o«-<
ss;ss$ ma ui^^^ ^^ii^
^KiQOh- O^CimCO r^MMOcO €Qr««0f-H«-4
^o7*>40 »«eoeo«c< ococnoco nce^ooo
ei^gDeoco ^"-"OQiQeo .-it-^^a* b-iQ^cii-i
aeh>38S> loud?^^ ^eoeococi Mc{e>i94C4
o^Ok^S eoxAoon ooci<-4or« «D^co«-4
^«3<o<o«> fr*t«aoooa oopootot^ t<*t«r^r^i»
! SSS3S SSSSSSS 8SSS9 SSRSS
S90»^e« geo^fioio coooo^eo «o<DOQQ-*
S^^fir* P^S^S ^«^»^c<« ciMclMeQ
«4««t^ t^oeoBciOk 0'^clco-<«* tocDr«o6a»
116 BLECTBOMAGKETS.
is neoesiary, thiB set of tables will, of course, give the proper length, L,
of the |>ermazient ooil. which in such cases is identical with Lt. If a oor-
recUon in mean length is necessarv and is such as to alter materially the
girth of the ooil, and, therefore, the radiating surface per unit of lr~ ^'
after making the correction in mean length as explained in a precTvuuw
pamgraph, and asoertainiiu; the calculated length of coil. L», by meanaoff
Table III, the final value for the length (L) of the permanent ooil may be
obtained by means of the formula
-O ^ C2)
O being the girth that the permanent ooil will have after oorreeting the
mean length per turn, and Oi the girth of the test ooil.
For convenience in making corrections in the mean length oer turn and
the girth of the finished coil. Table IV (divided into IVa to iVe inclusive)
has been prepared. This gives the depth of coU that will be obtained with
different numbers of layers of the standard siiee of magnet wire, single
and double cotton covered.
The table is based on the insulation thicknesses used by the Roebling
factory, and while the coil depths are given to the second and third decimal
places, it will, of course, be understoM that this is not intended as an in-
timation that coils can be wound in practice to any such degree of accuracy,
even if the insulation ran absolutely uniform always, which it does not do.
The full figures are given in this, as in Tables I and II, merely in order thi^
one may see what the exact theoretical values are. The table has not been
made to include very small sixes of wire, for the reason that any approach
to accuracy in calculations based on the insulated diameters of sudti wires
is impossible.
For coils wound around a continuously convex surface, such as that
of a bobbin for a round magnet core or one of oval cross section, the mean
length per turn of wire ia roidily obtained by means of the formula
9 + ir d - L» (8)
in which g is the sirth of the bobbin or former in which the ooil is wound
and d is the depth of the winding (in inch measure,or whatever unit of
linear measurement may be used; not in layers). The girth of the ooil
will be obtainable by means of the formula
a + 2»d-(? (4)
The mean length per turn in a coil wound on a bobbin of substantially
rectangular cross section will be greater than the value given this formula
on account of the bulging of the wire away from the core in the parts of
the winding which cover the straight surfaces of the bobbin or former.
This is also true, and to a greater extent, of the girths of the finished
coil.
WINDING OF BLECTBOMAGNBTS.
117
le
•r Magnet €)mtL
It
LfiDsih of Test Coil, Lu
Ih
U
.96
If
If
li
1.19
2
1.27
2i
1.35
21
1.43
21
1.5
2*
1.58
21
2i
21
A . .
1.03
1.11
1.66
1.74
1.82
.425 .
.98
1.06
1.14
1.22
1.31
1.39
1.47
1.55
1.63
1.71
1.8
1.87
.45. .
1.01
1.09
1.17
1.26
1.34
1.43
1.51
1.6
1.68
1.76
1.85
1.93
.475 .
1.08
1.12
1.21
1.29
1.88
1.47
1.55
1.64
1.72
1.81
1.9
1.98
J& . .
1.06
1.15
1.24
1.33
1.42
1.5
1.59
1.68
1.77
1.86
1.95
2.03
.525 .
1.00
1.18
1.27
1.36
1.45
1.54
1.63
1.72
1.81
1.9
1.99
2.08
.56. .
1.12
1.21
1.3
1.39
1.48
1.58
1.67
1.76
1.86
1.95
2.04
2.13
.675 .
1.14
1.23
1.33
1.42
1.62
1.61
1.71
1.8
1.9
1.99
2.09
2.18
.6 . .
1.16
1.26
1.36
1.45
1.55
1.65
1.74
1.84
1.94
2.03
2.13
2.23
.625 .
1.18
1.29
1.38
1.48
1.58
1.68
1.78
1.88
1.98
2.08
2.17
2.27
.65. .
1.21
1.31
1.41
1.51
1.61
1.71
1.82
1.92
2.02
2.12
2.22
2.32
.675 .
1.23
1.34
1.44
1.54
1.64
1.76
1.85
1.95
2.05
2.16
2.26
2.36
.7 . .
1.26
1.36
1.47
1.57
1.67
1.78
1.88
1.99
2.09
2.2
2.3
2.41
.725 .
1.28
1.38
1.49
1.6
1.7
1.81
1.92
2.02
2.13
2.24
2.34
2.45
-75 . .
1.3
1.41
1.52
1.62
1.73
1.84
1.95
2.06
2.17
2.27
2.38
2.49
.8 . .
1.34
1.46
1.57
1.68
1.79
1.9
2.01
2.13
2.24
2.36
2.46
2.57
.65. .
1.30
1.5
1.61
1.73
1.85
1.96
2.08
2.19
2.31
2.42
2.54
2.66
-9 . .
1.42
1.54
1.66
1.78
1.9
2.02
2.14
2.25
2.37
2.49
2.61
2.73
.95. .
1.46
1.58
1.71
1.83
1.95
2.07
2.19
2.32
2.44
2.56
2.68
2.8
1. . . .
1.5
1.63
1.75
1.88
2.
2.13
2.25
2.38
2.5
2.63
2.75
2.88
1.05. .
1.54
1.67
1.79
1.92
2.06
2.18
2.31
2.44
2.56
2.69
2.82
2.95
l.l . .
1.67
1.71
1.84
1.97
2.1
2.23
2.36
2.40
2.62
2.75
2.88
3.02
1.2 . .
1.64
1.78
1.92
2.05
2.19
2.33
2.47
2.6
2.74
2.88
3.01
3.15
K3 . .
1.71
1.85
1.99
2.14
2.28
2.42
2.57
2.71
2.85
3.
3.14
3.28
1.4 . .
1.78
1.92
2.07
2.22
2.37
2.51
2.66
2.81
2.96
3.11
3.25
3.4
1-5 . .
1.84
1.99
2.14
2.8
2.45
2.6
2.76
2.91
3.06
3.22
3.37
3.52
1.6 . .
1.0
2.06
2.21
2.37
2.53
2.69
2.85
3.01
3.16
3.32
3.48
3.64
1.7 . .
1.06
2.12
2.28
2.45
2.61
2.77
2.93
3.1
3.26
3.42
3.59
3.75
1.8 . .
2.01
2.18
2.35
2.52
2.68
2.85
3.02
3.19
3.35
3.52
3.69
3.86
1-9 . .
2.07
2.24
2.41
2.59
2.76
2.93
3.1
3.27
3.45
3.62
8.79
3.96
2. . . .
2.12
2.3
2.48
2.65
2.83
3.
3.18
3.36
3.54
3.71
8.89
4.07
2.1 . .
2.17
2.36
2.54
2.72
2.9
3.08
3.26
3.44
3.62
3.81
3.90
4.17
2.2 . .
2.23
2.41
2.6
2.78
2.97
3.15
3.34
3.52
3.71
3.89
4.08
4.27
2.3 . .
2.28
2.47
2.65
2.84
3.03
3.22
3.41
3.6
3.79
3.98
4.17
4.36
2.4 . .
2.32
2.52
2.71
2.91
3.1
3.29
3.49
3.68
3.87
4.07
4.26
4.46
The Above numbers (in the body of the table) are oorrected lengths, Zc
118
ELECTROMAGNETS.
Tal»le mb.— ff^r carvecttnc
of Mac^et Call*
It
Length of Test Coil. Ll
Ih
3
1.9
3i
1.98
3i
2.06
31
2.14
3*
2.22
31
2.3
3i
2.37
31
4
4t
4i
41
.4 . .
2.45
2.63
2.61
2.00
2.77
.425 .
1.96
2.04
2.12
2.2
2.28
2.36
2.45
2.53
2.61
2.60
2.77
2.85
.45 . .
2.01
2.1
2.18
2.26
2.35
2.43
2.52
2.6
2.68
2.77
2.85
2.04
.475 .
2.07
2.15
2.24
2.33
2.41
2.5
2.58
2.67
2.76
2.84
2.03
3.02
.5 . .
2.12
2.21
2.3
2.39
2.48
2.56
2.65
2.74
2.83
2.92
3.01
3.00
.525 .
2.18
2.26
2.36
2.45
2.54
2.63
2.72
2.81
2.9
2.90
3.08
3.17
.55 . .
2.23
2.32
2.41
2.5
2.60
2.69
2.78
2.87
2.97
3.06
3.15
3.28
.576 .
2.28
2.37
2,46
2.56
2.65
2.75
2.84
2.94
3.03
3.13
3.22
3.31
.6 . .
2.32
2.42
2.52
2.62
2.71
2.81
2.91
3.
3.1
3.2
3.20
3.30
.625 .
2.37
2.47
2.57
2.67
2.77
2.87
2.97
3.06
3.16
3.26
3.36
3.40
.65 . .
2.42
2.52
2.62
2.72
2.82
2.92
3.02
3.13
3.23
3.83
3.43
3.53
.675 .
2.46
2.57
2.67
2.77
2.88
2.98
3.08
3.19
3.29
3.30
3.40
3.50
.7 . .
2.51
2.62
2.72
2.82
2.93
3.03
3.14
3.24
3.35
3.45
3.56
3.66
.725 .
2.56
2.66
2.77
2.87
2.98
3.09
3.19
3.3
3.41
3.51
3.62
3.73
.75 . .
2.6
2.71
2.81
2.92
3.03
3.14
3.25
8.36
3.46
3.57
3.68
3.70
.8 . .
2.68
2.8
2.91
3.02
3.13
3.24
3.35
8.47
8.68
3.60
3.8
3.01
.85 . .
2.77
2.88
3.
8.11
3.23
3.34
3.46
3.57
8.69
3.81
3.02
4.03
.9 . .
2.84
2.97
3.09
3.2
3.32
3.44
3.56
3.68
3.8
3.01
4.03
4.15
.06 . .
2.92
3.05
3.17
3.29
3.41
3.53
3.66
3.78
3.9
4.02
4.14
4.26
1. . . .
3.
3.13
3.25
3.38
3.5
3.63
3.75
8.88
4.
4.13
4.25
4.38
1.05 . .
3.07
3.2
8.33
8.46
l:t?
3.72
3.84
3.97
4.1
4.23
4.36
4.48
1.1 . .
3.14
3.28
3.41
8.54
3.8
3.93
4.06
4.2
4.38
4.46
4.60
1.15 . .
3.21
3.35
3.49
3.62
3.75
3.89
4.02
4.16
4.29
4.42
4.56
4.60
1.2 . .
3.28
3.44
3.58
3.72
3.85
3.99
4.13
4.27
4.4
4.54
4.68
4.82
1.25 . .
3.35
3.49
3.63
3.77
3.91
4.05
4.19
4.33
4.47
4.61
4.75
4.80
1.3 . .
8.42
3.56
3.71
3.85
8.99
4.13
4.28
4.42
4.56
4.7
4.85
4.00
1.35 . .
3.49
3.63
3.78
3.92
4.07
4.21
4.36
4.5
4.65
4.79
4.04
5.08
1.4 . .
3.55
3.7
3.85
3.99
4.14i4.29
4.44
4.59
4.73
4.88
5.03
5.18
1.45 . .
3.61
3.76
3.91
4.07
4.22:4.37
4.52
4.67
4.82
4.97
5.12
6.27
1.5 . .
3.67
3.83
3.98
4.13
4.29
4.44
4.59
4.75
4.9
5.05
6.21
5.30
1.6 . .
3.85
3.95
4.11
4.27
4.43
4.59
4.75
4.9
5.06
5.22
6.38
5.53
1.7 . .
3.91
4.08
4.24
4.4
4.56
4.73
4.89
5.05
5.22
5.38
5.54
5.71
1.8 . .
4.02
4.19
4.36
4.53
4.7
4.86
5.03
5.2
5.37
5.54
5.7
5.87
1.9 . .
4.14
4.31
4.48
4.65
4.83
6.
5.17
5.34
5.51
5.09
6.86
6.03
2. . . .
4.25
4.42
4.6
4.77
4.95
5.13
5.31
5.48
5.66
5.83
6.01
0.10
The above numbers (in the body of the table) are corrected lengthB, Lc
^
mSDISQ OF BLEGTROMAOirETS.
119
Tabl« me. — For correcilnr IiCBi^tli of IHagvot Coll.
/(
length of Test Coil, Lu
Ik
4*
3.18
41
3.27
41
3.36
4i
3.45
6
3.64
5i
3.62
6i
3.71
61
3.8
5i
61
6}
4.07
61
.5 . .
3.89
3.98
4.16
.525 .
3.26
3.35
3.44
3.53
3.62
3.71
3.81
3.9
3.99
4.08
4.17
4.26
.55. .
3.34
3.43
3.52
3.62
3.71
3.8
3.9
3.99
4.08
4.17
4.27
4.36
.575 .
3.41
3.51
3.6
3.7
3.79
3.89
3.98
4.08
4.17
4.27
4.36
4.46
.6 . .
3.49
3.58
3.68
3.78
3.87
3.97
4.07
4.16
4.26
4.36
4.46
4.66
.825 .
3.56
3.66
3.76
3.86
3.95
4.05
4.15
4.25
4.85
4.45
4.56
4.66
.65. .
3.63
3.73
3.83
3.93
4.03
4.13
4.23
4.33
4.43
4.64
4.64
4.74
.m .
3.7
3.8
3.9
4.01
4.11
4.21
4.31
4.42
4.52
4.62
4.72
4.83
.7 . .
3.77
3.87
3.97
4.08
4.18
4.29
4.39
4.6
4.6
4.71
4.81
4.92
.725 .
3.83
3.94
4.04
4.15
4.26
4.37
4.47
4.68
4.68
4.79
4.9
5.0
.75. .
3.9
4.01
4.11
4.22
4.33
4.44
4.55
4.66
4.76
4.87
4.98
6.09
.775 .
4.01
4.07
4.18
4.29
4.4
4.51
4.62
4.73
4.84
4.96
6.06
6.17
.8 . .
4.03
4.14
4.25
4.36
4.47
4.68
4.7
4.81
4.92
6.03
5.14
6.25
.825 .
4.09
4.2
4.32
4.43
4.64
4.66
4.77
4.88
5.
6.11
6.22
6.34
.85. .
4.15
4.27
4.38
4.5
4.61
4.73
4.84
4.96
6,07
6.19
6.3
5.42
.875 .
4.21
4.33
4.44
4.56
4.68
4.8
4.91
6.03
5.16
6.26
6.38
5.6
.» . .
4.27
4.39
4.51
4.63
4.74
4.86
4.98
6.1
5.22
6.34
6.46
6.67
.825 .
4.33
4.45
4.67
4.69
4.81
4.93
5.05
6.17
5.29
6.41
5.63
6.66
.85. .
4.39
4.51
4.63
4.76
4.87
5,
6.12
6.24
5.36
6.48
5.61
6.73
1. . .
4.5
4.63
4.76
4.88
5.
6.13
6.26
6.38
6.5
5.63
6.75
6.88
1.05. .
4.61
4.74
4.87
5.
5.12
5.26
6.38
6.51
6.64
6.76
5.89
6.02
1.1 . .
4.72
4.85
4.98
6.11
5.26
6.38
6.61
6.64
6.77
6.9
6.03
6.16
1.15.-.
4.83
4.96
5.09
6.23
5.36
6.6
6.63
5.76
6.9
6.03
6.17
6.3
1.2 . .
4.96
5.07
5.2
5.34
6.48
6.61
6.76
5.89
6.03
6.16
6.3
6.44
1.25. .
5.03
5.17
5.31
6.46
5.59
5.73
5.87
6.01
6.16
6.20
6.43
6.57
13 . .
5.13
5.27
5.42
6.66
5.7
5.84
6.99
6.13
6.27
6.41
6.66
6.7
1.35. .
5.23
6.37
5.52
6.67
5.81
6.96
6.1
6.25
6.39
6.64
6.68
6.83
1.4 . .
5.33
6.47
5.62
6.77
5.92
6.07
6.21
6.36
6.51
6.66
6.81
6.96
1.46. .
5.42
5.57
5.72
6.87
6.02
6.17
6.32
6.47
6.62
6.77
6.93
7.08
1.5 . .
5.51
5.67
6.82
5.97
6.12
6.28
6.43
6.58
6.74
6.89
7.04
7.2
1.55. .
5.6
5.76
5.91
6.07
6.23
6.38
6.54
6.69
6.86
7.
7.16
7.32
i.e . .
5.69
6.85
6.01
6.17
6.33
6.48
6.64
6.8
6.96
7.12
7.27
7.43
1.65. .
5.78
6.94
6.1
6.26
6.42
6.68
6.74
6.91
7,07
7.23
7.30
7.66
1.7 . .
5.87
6.03
6.19
6.36
6.62
6.68
6.86
7.01
7.17
7.33
7.5
7.66
1.75. .
5.96
6.12
6.28
6.46
6.61
6.78J6.96
7.11
7.28
7.44
7.61
7.77
1.8 . .
6.04
6.21
6.37
6.54
6.71
6.88
7.06
7.21
7.38
7.55
7.72
7.88
1.85. .
6.12
6.29
6.46
6.636.8
6.97
7.14
7.31
7.48
7.65
7.82
7.99
18 . .
6.2
6.38
6.65
6.72 6.89
7.07
7.24
7.41
7.68
7.75
7.03
8.1
I*- •
6.286.46
6.63
6.81,6.08
7.167.33
7.51
7.68
7.86
8.03
8.21
2. . . .
6.37 6.54
6.72
6.9
7.07
7.25 7.42
7.6
7.78
7.96
8.13
8.31
(
The above numbera (in the body of the table) are corrected lengths, Lc,
120
BLBCTB0B1A.ONBTS.
Table md. — for corractlar I<cnMrtli of Maff»«t C«Pil.
It
Tipjigth of Test Coil, Lu
Ih
6
6i
4.33
6i
4.44
61
4.61
6i
4.6
61
4.69
6i
4.77
61
4.86
7
4.95
7i
7i
71
.6 . .
4.24
6.04
6.13
5.22
.525 .
4.35
4.44
4.63
4.62
4.71
4.8
4.80
4.98
5.07
6.16
5.26
5.34
.55 . .
4.45
4.54
4.64
4.73
4.82
4.91
6.01
5.1
6.10
5.20
5.38
6.47
.575 .
4.55
4.65
4.74
4.83
4.93
6.02
5.12
5.21
6.31
5.4
6.5
5.50
.6 . .
4.65
4.75
4.84
4.94
5.04
6.13
6.23
6.33
6.42
5.62
5.62
5.71
.625 .
4.75
4.84
4.94
5.04
5.14
6.24
6.34
5.44
5.53
5.63
5.73
5.83
.65 . .
4.84
4.04
6.04
5.14
6.24
6.84
5.44
5.54
5.64
6.76
5.85
5.05
.675 .
4.03
5.03
6.14
5.24
5.34
6.44
6.66
6.65
5.76
5.86
6.06
6.06
.7 . .
5.02
5.13
6.23
5.33
5.44
6.54
5.66
5.76
6.86
6.06
6.07
6.17
.725 .
6.11
5.22
5.32
5.43
6.53
6.64
5.76
5.86
6.06
6.07
6.17
6.28
.75 . .
5.2
5.3
5.41
6.52
5.63
6.74
6.85
5.05
6.06
6.17
6.28
6.30
.775 .
5.28
5.30
5.5
5.61
5.72
5.83
5.04
6.06
6.16
6.27
6.30
6.40
.8 . .
5.37
5.48
5.69
5.7
5.81
5.93
6.04
6.16
6.26
6.37
6.40
6.6
.825 .
5.45
5.56
5.68
5.79
6.91
6.02
6.13
6.26
6.36
6.47
6.50
6.7
.85 . .
6.53
5.65
5.76
6.88
5.99
6.11
6.22
6.34
6.46
6.67
6.00
6.8
.875 .
5.61
5.73
5.86
6.96
6.08
6.2
6.31
6.43
6.56
6.67
6.78
6.0
.9 . .
5.60
5.81
5.93
6.06
6.17
6.29
6.4
6.62
6.64
6.76
6.88
7.
.025 .
5.77
5.80
6.01
6.13
6.25
6.37
6.40
6.61
6.73
6.86
6.07
7.00
.05 . .
5.85
5.07
6.09
6.21
6.34
6.46
6.68
6.7
6.82
6.05
7.07
7.10
1. . . .
6.
6.13
6.25
6.38
6.6
6.63
6.76
6.88
7.
7.18
7.25
7.38
1.06 . .
6.15
6.28
6.41
6.53
6.66
6.79
6.02
7.05
7.17
7.8
7.43
7.66
1.1 . .
6.29
6.43
4.56
6.69
6.82
6.95
7.08
7,21
7.34
7.47
7.61
7.74
1 . 15 . .
6.44
6.57
6.7
6.84
6.97
7.11
7.24
7.37
7.61
7.64
7.78
7.91
1.2 . .
6.57
6.71
6.86
6.99
7.12
7.26
7.39
7.63
7.67
7.81
7.04
8.08
1.25 . .
6.71
6.85
6.99
7.13
7.27
7.41
7.55
7.69
7.83
7.07
8.11
8.25
1.3 . .
6.84
6.08
7.13
7.27
7.41
7.66
7.7
7.84
7.08
8.13
8.27
8.41
1.35 . .
6.07
7.12
7.26
7.41
7.65
7.7
7.84
7.99
8.13
8.28
8.43
8.57
1.4 . .
7.1
7.25
7.4
7.54
7.69
7.84
7.99
8.13
8.28
a. 43
8.68
8.78
1.45 . .
7.23
7.38
7.63
7.68
7.83
7.98
8.13
8.28
8.43
8.58
8.73
8.88
1.5 . .
7.35
7.5
7.66
7.81
7.96
8.11
8.27
8.42
8.67
8.73
8.88
0.08
1.55 . .
7.47
7.63
7.78
7.94
8.09
8.25
8.4
8.66
8.72
8.87
0.03
9.18
1.6 . .
7.50
7.75
7.91
8.07
8.22
8.38
8.54
8.7
8.86
0.01
0.17
0.33
1.65 . .
7.71
7.87
8.03
8.19
8.35
8.51
8.67
8.83
8.00
0.16
0.31
9.47
1.7 . .
7.82
7.99
8.15
8.31
8.48
8.64
8.8
8.96
0.13
0.20
0.45
9.62
1.75 . .
7.04
8.1
8.27
8.43
8.6
8.77
8.93
9.09
0.26
0.43
0.50
0.76
1.8 . .
8.05
8.22
8.39
8.55
8.72
8.89
9.06
9.22
0.30
0.66
0.73
0.0
1.85 . .
8.16
8.33
8.5
8.67
8.84
9.01
9,18
9.36
0.52
0.60
0.86
10.03
1.0 . .
8.27
8.44
8.62
8.79
8.96
9.13
9.3
9.48
0.66
0.82
0.00
10.17
1.06 . .
8.38
8.65
8.73
8.9
9.08
9.25
9.43
9.6
0.78
0.06
10.13
10.3
2. . . .
8.49
8.66
8.84
9.02
9.19
9.37
9.56
9.72
0.0
10.08
10.25
10.43
The ftbove numbers (in the body of the table) are corrected leogths, Le*
WINDIKO OF ELECTROMAGNETS.
121
VaMe TVm. — lilBear flimce •ocniH*' l»7 Marl« C«ttom
or
2
3
4
5
6
7
S
9
10
11
12
13
14
U
le
17
18
19
20
21
24 .
25 .
21 .
27 .
28 .
29 .
» .
SI .
32 .
S3 .
34.
35 .
3S.
37.
41
42
43
44
45
47
48
»
52
54
54
58
60
52
54
Wire Numbers, B. A 8. Gauge :
0.432!0.388
0.648
0.864
1.08
1.296
1.512
1.728
1.994
2.16
2.38
2.59
2.81
3.03
3.24
3.46
3.67
3.89
4.11
4.32
4.53
4.76
4.97
0.582
0.776
0.97
1.164
358
552
746
94
14
33
52
72
91
11
1.
1.
I.
1.
2.
2.
2.
2.
2.
3.
3.3
3.49
3.69
3.88
4.07
4.27
4.46
4.65
4.85
5.06
0.344
0.516
0.688
0.86
1.032
1.
1.
1.
1.
1.
2.
2.
2.
2.
2.
2.
8.
3.
3.
3.
3.
3
4
4
4
4
4
4
5
204
376
548
72
89
07
24
41
58
75
93
1
27
44
61
.78
.95
.125
.3
.47
.64
.81
.98
.16
0.308
0.462
0.616
0.77
0.924
1.078
1.232
1.386
1.54
1.69
1.85
2.
2.16
2.31
2.47
2.62
2.77
2.93
3.08
3.24
3.89
3.54
3.69
3.85
4.
4.16
4.31
4.46
4.62
4.77
4.98
5.08
8
9
0.274
0.411
0.548
0.685
0.822
0.959
1.096
1.233
1.37
1.51
1.64
1.78
1.92
2.06
2.19
2.33
2.47
2.61
2.74
2.88
3.02
3.15
3.29
3.43
3.56
3.7
3.83
3.97
4.11
25
38
52
65
79
93
.69
.81
.93
3.05
3.17
5.07
0.244
0.366
0.488
0.61
0.732
0.854
0.976
1.098
1.22
1.34
1.47
1.59
1.71
1.83
1.95
2.06
2.2
2.32
2.44
2.56
29
41
54
66
78
3.9
4.02
4.14
4.27
4.39
.51
.63
4.76
4.88
5.
10
0.216
0.324
0.432
0.54
0.648
0.756
0.864
0.972
1.08
1.19
1.3
1.41
1.51
1.62
1.73
1.84
1.95
2.05
2.16
2.27
2.38
2.49
2.59
2.7
2.81
2.92
3.03
3.13
3.24
3.35
3.45
3.56
3.67
3.78
3.89
3.99
4.1
4.21
4.32
4.42
.53
.64
4.75
4.86
4.97
11
0.194
0.291
0.388
0.485
0.582
0.679
0.776
0.873
0.97
1.07
1.17
1.26
1.36
1.46
1.55
1.65
1.75
1.85
1.94
2.04
2.14
2.23
2.33
2.43
2.52
2.62
2.72
2.82
2.91
3.
3.1
3.2
3.29
3.39
3.49
3.59
3.68
8.78
3.88
3.97
4.07
4.17
4.27
4.36
4.46
.56
.66
4.76
4.85
12
0.174
0.261
0.348
0.435
0.522
0.609
0.606
0.783
0.87
0.96
1.05
1.13
1.22
1.31
1.39
1.48
1.67
1.66
1.74
1.83
1.92
2.
2.09
2.18
2.26
2.35
2.44
2.53
2.61
2.7
2.79
2.87
2.96
3.04
3.13
3.22
3.3
3.39
3.48
3.56
3.65
3.74
3.83
3.91
4.
4.09
4.18
4.27
4.35
4.52
4.7
4.87
13
0.16
0.24
0.31
0.39
0.47
0.55
0.63
0.70
0.78
0.86
0.94
1.02
1.09
1.17
1.25
1.83
1.44
1.48
1.56
1.64
1.72
1.8
1.87
1.95
2.03
2.11
2.19
2.26
2.34
2.42
2.5
2.58
2.65
2.73
2.81
2.89
2.97
3.04
3.12
3.2
3.27
3.35
3.43
3.51
3.59
3.66
3.74
3.82
3.95
4.06
4.22
4.37
4.52
4.68
14
oTii
0.21
0.28
0.35
0.42
0.49
0.56
0.63
0.7
0.77
0.84
0.01
.98
1.05
1.12
1.19
1.26
1.33
1.4
1.47
1.54
1.61
1.68
1.75
1.82
1.89
1.96
2.03
2.1
2.17
2.24
2.31
2.38
2.45
2.52
2.59
2.66
2.73
2.8
2.87
2.04
3.01
3.08
3.15
3.22
3.29
3.36
3.43
3.6
3.64
3.78
3.92
4.06
4.2
4.34
4.48
122
ELEGTBOMAONBTS.
Turns or
Wire Numben. B. & 8. Gauge:
Layers. •
15 .
16
17
18
19
20
21
22
23
24
6. . . .
0.38
0.34
0.31
0.28
0.25
0.23
0.2
0.19
0.17
' O.U
7. . . .
0.44
0.4
0.36
0.32
0.29
0.27
0.24
0.22
0.2
0.17
8. . . .
0.5
0.46
0.41
0.37
0.34
0.8
0.27
0.25
0.22
\ 0.2
9. . . .
0.57
0.51
0.46
0.41
0.38
0.34
0.81
0.28
0.25
> 0.21
10. . . .
0.63
0.57
0.51
0.46
0.42
0.38
0.34
0.31
0.28
E 0.2i
11 ... .
0.69
0.63
0.56
0.61
0.46
0.42
0.37
0.34
0.81
0.27
12. . . .
0.76
0.68
0.61
0.56
0.5
0.46
0.41
0.37
0.34
0.8
13 ... .
0.82
0.74
0.66
0.6
0.55
0.49
0.44
0.4
0.36
0.33
14 ... .
0.88
0.8
0.71
0.64
0.59
0.63
0.48
0.43
0.30
0.3C
16 ... .
0.96
0.85
0.76
0.69
0.63
0.67
0.61
0.46
0.42
0.38
16
1.01
0.91
0.82
0.74
0.67
0.61
0.64
0.6
0.46
0.4
17 ... .
1.07
0.97
0.87
0.78
0.72
0.65
0.68
0.68
0.48
0.42
18. . . .
1.13
1.03
0.92
0.83
0.76
0.68
0.61
0.66
0.6
0.46
19 ... .
1.2
1.08
0.97
0.87
0.8
0.72
0.66
0.69
0.63
0.47
20 ... .
1.26
1.14
1.02
0.92
0.84
0.76
0.68
0.62
0.56
0.6
21 ... .
1.32
1.2
1.07
0.97
0.88
0.8
0.71
0.65
0.69
0.52
22 ... .
1.39
1.25
1.12
1.01
0.92
0.84
0.75
0.68
0.62
0.56
23. . . .
1.45
1.31
1.17
1.06
0.97
0.87
0.78
0.71
0.64
0.57
24 ... .
1.51
1.37
1.22
1.1
1.01
0.91
0.82
0.74
0.67
0.6
25 ... .
1.57
1.42
1.27
1.15
1.05
0.95
0.86
0.78
0.7
0.62
26. . . .
1.64
1.48
1.33
1.2
1.09
0.99
0.88
0.81
0.73
0.65
27 ... .
1.7
1.54
1.38
1.24
1.13
1.03
0.92
0.84
0.76
0.67
28. . . .
1.76
1.6
1.43
1.29
1.18
1.06
0.95
0.87
0.78
0.7
29. . . .
1.83
1.65
1.48
1.33
1.22
1.1
0.99
0.9
0.81
0.72
30 ... .
1.89
1.71
1.53
1.38
1.26
1.14
1.02
0.93
0.84
0.75
31 ... .
1.95
1.77
1.58
1.43
1.3
1.18
1.05
0.96
0.87
0.77
32 ... .
2.02
1.82
1.63
1.47
1.34
1.22
1.09
0.99
0.9
0.8
33 ... .
2.08
1.88
1.68
1.52
1.39
1.25
1.12
1.02
0.98
0.82
34 ... .
2.14
1.94
1.73
1.56
1.43
1.29
1.16
1.06 0.96
0.85
35. . . .
2.2
2.
1.78
1.61
1.47
1.33
1.19
1.08
0.98
0.87
36. . . .
2.27
2.05
1.84
1.66
1.51
1.37
1.22
1.12
1.01
0.9
37 ... .
2.33
2.11
1.89
1.7
1.56
1.41
1.26
1.16
1.04
0.92
38 ... .
2.39
2.17
1.94
1.75
1.6
1.44
1.29
1.18
1.06
0.95
39 ... .
2.46
2.22
1.99
1.79
1.64
1.48
1.33
1.21
1.09
0.97
40 ... .
2.52
2.28
2.04
1.84
1.68
1.52
1.36
1.24
1.12
1.
41 ... .
2.58
2.34
2.09
1.89
1.72
1.66
1.89
1.27
1.15
1.02
42 ... .
2.65
2.39
2.14
1.93
1.76
1.6
1.43
1.8
1.18
1.05
43 ... .
2.71
2.45
2.19
1.98
1.81
1.63
1.46
1.83
1.2
1 .07
44 ... .
2.77
2.51
2.24
2.02
1.85
1.67
1.5
1.36
1.23
1.1
45 ... .
2.83
2.56
2.29
2.07
1.89
1.71
1.63
1.89
1.26
1.12
46 ... .
2.9
2.62
2.35
2.12
1.93
1.75
1.66
1.43
1.29
1.15
47 ... .
2.96
2.68
2.4
2.16
1.97
1.79
1.6
1.46
1.32
1.17
48 ... .
3.02
2.73
2.45
2.21
2.02
1.82
1.63
1.49
1.34
1.2
49 ... .
3.09
2.79
2.5
2.25
2.06
1.86
1.67
1.62
1.37
1.22
60 ... .
3.15
2.85
2.55
2.3
2.1
1.9
1.7
1.66
1.4
1.25
62 ... .
3.27
2.96
2.65
2.39
2.18
1.98
1.77
1.61
1.46
1.8
54 ... .
3.4
3.08
2.75
2.48
2.27
2.05
1.84
1.67
1.61
1.35
56 ... .
3.53
3.19
2.86
2.58
2.35
2.13
1.9
1.74
1.67
1.4
58 ... .
3.65
3.31
2.96
2.67
2.44
2.2
1.97
1.8
1.62
1.45
60 ... .
3.78
3.42
3.06
2.76
2.52
2.28
2.04
1.86
1.68
1.5
62 ... .
3.91
3.53
3.16
2.85
2.6
2.36
2.11
1.92
1.74
1.55
64 ... .
4.03
3.65
3.26
2.94
2.69
2.43
2.18
1.98
1.79
1.0
66 ... .
4.16
3.76
3.37
3.04
2.77
2.51
2.24
2.06
1.85
1.65
68 ... .
4.28
3.88
3.47 3.13
2.86 2.58
2.31
2.11
1.9
1.7
70 ... .
4.41 3.99
3.57 3.22
2.94 2.66 2.381
2.17
1.96
1.75
WINDING OF ELECTROMAGNETS.
123
^
Wire Numbers,
B. A S.
Gauge:
Turns or
Lftyen.
17
18
19
20
21
22
23
24
72
3.67
3.31
3.02
2.74
2.45
2.23
2.02
1.8
74
3.77
3.4
3.11
2.81
2.52
2.29
2.07
1.85
76
3.88
3.6
3.19
2.89
2.58
2.36
2.13
1.9
78
3.98
3.58
3.28
2.96
2.65
2.42
2.18
1.95
SO
4.08
3.68
3.36
3.04
2.72
2.48
2.24
2.
82
4.18
3.77
3.44
3.12
2.79
2.54
2.3
2.05
84
4.28
8.86
3.53
3.19
2.86
2.6
2.35
2.1
86
4.39
3.96
3.61
3.27
2.92
2.67
2.41
2.15
88
4.49
4.05
3.7
3.34
2.99
2.73
2.46
2.2
»
4.59
4.14
3.78
3.42
3.06
2.79
2.52
2.25
82
4.23
3.86
3.5
3.13
2.85
2.58
2.3
M
4.32
3.95
3.57
3.2
2.91
2.63
2.35
W
4.42
4.03
3.65
3.26
2.98
2.69
2.4
88
4.51
4.12
3.72
3.33
3.04
2.74
2.45
100
4.6
4.2
3.8
3.4
3.1
2.8
2.5
102
■ • ■ •
4.28
3.88
3.47
3.16
2.86
2.55
■ « « •
4.37
3.95
3.54
3.22
2.91
2.6
106
....
4.45
4.08
3.6
3.29
2.97
2.65
• • • •
4.54
4.1
3.67
3.35
3.02
2.7
no
• « ■ •
• • • ■
4.18
3.74
3.41
3.08
2.75
112
• • • •
4.26
3.81
3.47
3.14
2.8
« • • •
4.33
3.88
3.53.
3.19
2.85
116
• • • •
4.41
3.94
3.6
3.25
2.9
• • • •
4.48
4.01
3.66
3.3
2.95
120
» • ■ «
....
4.56
4.08
3.72
3.36
3.
lE^aUe ITd. — IJ»«»r Jlpa«e occajpled Iby ]>oabIe Cottom-
Ccvrered 'Wfre».
Wire Numbers, B. dc S. Gauge:
1)uDsor
Uy«ra.
4
5
0.4
6
7
0.32
8
9
10
11
12
13
0.16
14
2. . .
0.444
0.356
0.284
0.252
0.224
0.202
0.182
0.15
3. . .
0.066
0.6
0.534
0.48
0.426
0.378
0.336
0.303
0.273:0.24
0.22
4. . .
0,888
0.8
0.712
0.64
0.568
0.504
0.448
0.404
0.364 0.32
0.29
5- . .
1.11
1.
0.89
0.8
0.71
0.63
0.56
0.505
0.455 0.4
0.36
8. . .
1.332
1.2
1.068
0.96
0.852
0.756
0.672
0.606
0.546
0.49
0.44
!■• •
1.554
1.4
1.246
1.12
0.994
0.882
0.784
0.707
0.637
0.57
0.51
8. . .
1.776
1.6
1.424
1.28
1.136
1.008
0.896
0.808
0.728
0.650.58
^l■ • •
1.998
1.8
1.602
1.44
1.278
1.134
1.008
0.909
0.819
0.730.66
?• • •
2.22
2.
1.78
1.6
1.42
1.26
1.12
1.01
0.91
0.8110.73
11. . .
2.442
2.2
1.958
1.76
1.562 1.386
i
1.232
1.111
1.001
0.89.0.8
{
ELEGTROMAONETS.
"MAmmmr Space occupied by lieable
Gorered ITire*. — OmftfUMd.
Turns or
Layers.
12.
13.
14.
15.
16.
17.
18.
19.
20
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
89.
40.
41.
42.
43.
44.
45.
46.
47.
48.
48.
50.
52.
54.
56.
58.
60.
62.
Wire Numbers, B. A 8. Gauge:
2.664
2.886
3.108
3.33
3.55
3.77
4.
4.22
4.44
4.66
4.88
2.4
2.6
2.8
3.
3.2
3.4
3.6
3.8
4.
4.2
4.4
4.6
4.8
5.
6
2.136
2.314
2.492
2.67
2.85
3.03
3.2
3.38
3.56
3.74
3.92
4.09
4.27
4.45
4.63
4.81
4.98
1.92
2.08
2.24
2.4
2.56
2.72
2.88
3.04
3.2
3.36
3.52
3.68
3.84
4.
4.16
4.32
4.48
4.64
4.8
4.96
8
1.704
1.846
1.988
2.13
2.27
2.41
2.56
2.77
2.84
2.98
3.12
3.27
3.41
3.55
3.69
3.83
3.98
4.12
4.2
4.4
4.54
4.6
4.8
4.97
9
1.512
1.638
1.764
1.89
2.01
2.14
2.27
2.39
2.52
2.65
2.77
2.9
3.02
3.15
3.28
3.4
3.53
3.65
3.78
3.91
4.03
4.16
4.28
4.41
4.54
4.66
4.79
4.91
5.04
10
1.344
1.456
1.568
1.68
1.79
1.9
2.02
2.13
2.24
2.35
2.46
2.58
2.09
2.8
2.91
3.02
3.14
3.25
3.36
3.47
3.58
3.7
3.81
3.92
4.03
4.14
4.26
4.37
4.48
4.59
4.7
4.82
4.93
5.04
11
1.212
1.313
1.414
1.51
1.62
1.72
1.82
1.92
2.02
2.12
2.22
2.32
2.42
2.53
2.63
2.73
2.88
2.93
3.03
3.13
3.23
3.33
3.43
3.54
3.64
3.74
3.84
3.94
4.04
4.14
4.24
4.34
4.44
4.55
4.66
4.76
4.85
12
1.002
1.183
1.274
1.36
1.46
1.55
1.64
1.73
1.82
1.91
2.
2.09
2.18
2.28
2.37
2.46
2.55
2.64
2.73
2.82
2.91
3.
3.00
3.19
8.28
3.87
3.46
3.55
3.64
8.78
3.82
3.91
4.
4.1
4.19
4.28
4.37
4.46
4.55
4.73
4.91
13
0.97
1.05
1.13
1.21
1.3
1.38
1.46
1.54
1.62
1.7
1.78
1.86
1.94
2.03
2.11
2.19
2.27
2.35
2.43
2.61
14
2.50
2.67
2.76
2.84
2.02
3.
3.08
3.16
3.24
3.32
3.4
3.48
3.56
3.65
3.73
3. '81
3.89
3.97
4.05
4.21
4.37
4.54
4.7
4.86
0.88
0.95
1.02
l.J
1.17
1.24
1.31
1.88
1.46
1.53
1.61
1.68
1.75
1.88
1.9
1.97
2.04
2.12
2.19
2.26
2.34
2.41
2.48
2.56
2.63
2.7
2.77
2.85
2.92
2.99
3.07
3.14
3.21
3.29
3.36
3.48
3.5
3.58
3.65
3.82
3.94
4.00
4.23
4.86
4.58
WINDING OF BLECTKOMAaNETS.
126
IWUe IVe.— UMcai* Space occupied 1»y ]»oiilile G«tt«m
Wire Numbers
, B. and S. Gauce:
Tumor
Uyen.
15
16
17
18
10
20
21
22
23
24
7. . . .
0.46
0.42
0.38
0.35
0.32
0.20
0.26
0.24
0.22
0.2
8. . . .
0.53
0.48
0.48
0.4
0.36
0.83
0.3
0.27
0.25
0.23
• • . . .
0.50
0.54
0.40
0.45
0.4
0.37
0.34
0.31
0.28
0.26
M. . . .
0.66
0.6
0.54
0.5
0.45
0;41
0.37
0.34
0.31
0.28
11. . . .
0.73
0.66
0.50
0.55
0.5
0.45
0.41
0.38
0.34
0.31
a. . . .
0.79
0.72
0.65
0.50
0.54
0.40
0.45
0.41
0.37
0.34
13. . . .
0.86
0.78
0.71
0.65
0.50
0.53
0.40
0.44
0.41
0.37
14. . . .
0.92
0.84
0.76
0.60
0.63
0.58
0.53
0.48
0.43
0.30
15. .*. .
0.00
0.0
0.81
0.74
0.68
0.62
0.56
0.51
0.47
0.42
18. . . .
1.06
0.06
0.86
0.70
0.72
0.66
0.6
0.54
0.5
0.45
17. . . .
1.12
1.02
0.02
0.84
0.77
0.7
0.64
0.58
0.53
0.48
18. . . .
1.10
1.08
0.07
0.80
0.81
0.74
0.86
0.61
0.56
0.51
19. . . .
1.25
1.14
1.03
0.04
0.86
0.78
0.71
0.65
0.59
0.53
». . . .
At
1.32
1.2
1.08
0.00
0.0
0.82
0.75
0.68
0.62
0.56
21. . . .
1.30
1.26
1.13
1.04
0.05
0.86
0.70
0.72
0.65
0.50
2. . . .
1.46
1.32
1.10
1.00
0.00
0.0
0.83
0.75
0.68
0.62
23. . . .
1.52
1.38
1.24
1.14
1.04
0.04
0.86
0.78
0.72
0.65
M. . . .
1.58
1.44
1.3
1.10
1.08
0.08
0.0
0.82
0.75
0.67
25. . . .
1.65
1.5
1.35
1.24
1.13
1.03
0.04
0.85
0.78
0.7
24. . . .
1.72
1.56
1.4
1.20
1.17
1.07
0.08
0.88
0.81
0.78
27. . . .
1.78
1.62
1.46
1.84
1.22
1.11
1.01
0.92
0.84
0.76
28. . . .
1.85
1.68
1.51
1.30
1.26
1.15
1.05
0.95
0.87
0.70
29- . . .
1.01
1.74
1.57
1.44
1.31
1.19
1.00
0.99
0.9
0.81
30. . . .
ikft
1.08
1.8
1.62
1.40
1.35
1.23
1.13
1.02
0.93
0.84
31. . . .
2.06
1.86
1.68
1.54
1.4
1.27
1.16
1.06
0.96
0.87
32. . . .
2.11
1.02
1.73
1.58
1.44
1.31
1.2
1.09
0.99
0.0
33. . . .
2.18
1.08
1.78
1.63
1.40
1.36
1.24
1.12
1.02
0.02
3*. . . .
A*
2.25
2.04
1.84
1.68
1.53
1.4
1.28
1.16
1.05
0.05
35. . . .
2.31
2.1
1.80
1.73
1.58
1.44
1.31
1.19
1.09
0.08
38. . . .
2.38
2.16
1.05
1.78
1.62
1.48
1.35
1.23
1.12
1.01
37. . . .
2.44
2.22
2.
1.83
1.67
1.52
1.30
1.26
1.15
1.04
38. . . .
2.61
2.28
2.06
1.88
1.71
1.56
1.43
1.29
1.18
1.07
38- . . .
2.58
2.84
2.11
1.03
1.76
1.6
1.46
1.33
1.21
1.00
*. . .
2.64
2.4
2.16
1.08
1.8
1.64
1.5
1.36
1.24
1.12
41. . . ".
2.71
2.46
2.22
2.03
1.85
1.68
1.54
1.4
1.27
1.15
42. . . .
JA
2.77
2.52
2.27
2.08
1.80
1.72
1.58
1.43
1.3
1.18
43. . . .
2.84
2.58
2.32
2.13
1.04
1.76
1.61
1.46
1.33
1.21
44. . . .
2.91
2.64
2.38
2.18
1.08
1.81
1.65
1.5
1.37
1.23
45. . . .
2.97
2.7
2.43
2.23
2.03
1.85
1.69
1.53
1.4
1.26
48. . . .
3.04
2.76
2.40
2.28
2.07
1.80
1.73
1.57
1.43
1.20
47. . . .
3.1
2.82
2.54
2.33
2.12
1.03
1.76
1.6
1.46
1.32
48. . . .
3.17
2.88
2.50
2.38
2.16
1.07
1.8
1.63
1.49
1.34
49. . . .
PA
3.23
2.04
2.65
2.43
2.21
2.01
1.84
1.67
1.62
1.37
50. . . .
3.3
3.
2.7
2.47
2.25
2.05
1.87
1.7
1.55
1.4
52. . . .
3.43
3.12
2.81
2.57
2.34
2.13
1.95
1.77
1.61
1.46
{
126
ELECTROMAGNETS.
Table IV««
MAn^mv Space occapled bjr DoaMa d
Covered ^^ire**^ Continued.
Wire numbersp B. and S. Gauge.
Turns or
layers.
1
15
16
17
18
10
20
21
22
23
24
54. . . .
3.56
3.24
2.92
2.67
2.43
2.22
2.03
1.84
1.67
1.51
50. . . .
3.7
3 .36
3.03
2.77
2.52
2.3
2.1
1.9
1.74
1.57
58. . . .
3.83
3.48
3.13
2.87
2.61
2.38
2.18
1.97
1.8
1.63
60. . . .
8.06
3.6
3.24
2.97
2.7
2.46
2.25
2.04
1.86
1.68
62. . . .
4.00
3.72
3.35
3.07
2.79
2.54
2.33
2.11
1.92
1.74
64. . . .
4.23
3.84
3.46
3.17
2.88
2.63
2.4
2.18
1.00
1.79
66. . . .
4.36
3.96
3.57
3.27
2.07
2.71
2.48
2.25
2.05
1.85
68. . . .
4.49
4.08
3.67
3.37
3.06
2.79
2.55
2.31
2.11
1.01
70. . . .
4.62
4.2
3.78
3.47
3.15
2.87
2.63
2.38
2.17
1.96
72 ... .
4.75
4.32
3.89
3.57
3.24
2.95
2.7
2.45
2.23
2.02
Turns or
layers.
74
76
78
80
82
84
86
88
90
92
94
96
98
100
102
104
106
108
110
112
114
116
118
120
122
Wire Numbers, B. & S. Gauge:
17
4
4
4
4
4
4
4
4
11
21
32
43
54
65
75
18
3,67
3.76
3.86
3.96
4.06
4.16
4.26
4.36
4.46
4.56
4.66
4.75
19
3.33
3.42
3.51
3.6
3.69
.78
.87
.96
.05
.14
4.23
4.32
4.41
4.5
4.59
4.68
20
3.04
3.13
3.2
3.28
3.36
3.45
3.53
3.61
3.69
3.77
3.86
3.94
4.02
4.1
4.18
4.27
4.35
4.43
4.51
4.59
21
2.78
2.85
2.93
3.
3.08
3.15
3.23
3.3
3.38
3.45
3.53
3.6
3.68
3.75
3.83
3.9
3.98
05
13
2
4.28
4.35
4.43
4.5
22
2.52
2.59
2.65
2.72
2.79
2.86
2 93
2.99
3.06
3.13
3.2
3.27
3.33
3.4
3.47
3.54
3.61
3.67
3.74
3.81
3.88
3.05
4.01
4.08
4.15
23
2.3
2.36
2.42
2.48
2.54
2.61
2.67
2.73
2.79
2.86
2.92
2.98
3.04
3.1
3.16
3.23
3.29
8.35
3.41
3.47
3.54
3.6
3.66
3.72
3.78
24
2.07
2.13
2.10
2.24
2.3
2.35
2.41
2.47
2.52
2.58
2.63
2.60
2.75
2.8
2.86
2.91
2.97
3.03
3.08
3.14
3.19
3.25
3.31
3.36
3.42
^
WINDING OP ELECTROMAGNETS. 127
Altera»tini^C«iTent Slectrovaffmct*.
^The cores of etectromaf^nets to be used with alternating currents must
> tatmiDAtedf and the laminations must run at right angles to the direc-
n in which eddy currents would be set up. Eddy currents tend to cir-
jeulate parallel to the coils of the wire, and tne laminations must, therefore,
m longitudinal to or parallel with the axis of the cores.
! The ootla of an alternating-current electromagnet off^* more resistance
to the passage of the alternating current than the mere resistance of the
eooductor in ohms. ' This extra resistance is called inditetance, and this
eomluaed with the resistance of the conductor in ohms produces the quality
criled impedance. (See Index for Impedance, etc.)
If L -B coefficient of self-induction,
N -" cycles per second,
R •■ resistance,
Impedance - V^a -f 4 irW'L^;
MaTimum current •—
Mean current »
Maximum E.M.F.
■ ■ ■ «
Impedance
Mean E.M.F.
Impedance.
I
B[e*tliiflr •f TUKwktem^t Cell*.
Profbbsor Forbes.
/ «B current permissible.
r( -■ resistance of coil at permissible temperature.
PoToiBsible temperature » cold r X 1.2.
t * rise in temperature C**.
« -> sq. cms. surface of coil exposed to air.
-v/^
.0003 XtX9
.24 X rj
Oiarles R. Uoderhill gives the following formula as having been found
by practise ^e moet accurate and complete for the design of plunger electro-
Let P -> pull in pounds.
B -> flux density in the working air-gap.
I ■- length of the air-gap.
IW — ampere-turns in the winding.
A — cross section of plunger in sq. in.
P» » pull at 10,000 ampere-turns and 1 sq. in. of plunger,
n "■ ampere-turn factor.
L " length of the winding in inches.
Then, the pull due to an iron-clad solenoid is
APe (/AT - n)
P -
10,000 - n
and, at points along the uniform range of solenoids, the pull for the plunger
dcctromBgnet willbe
p . X ( ^^ + ^^^-— ^-^Y
^ ^ V 7.075,600 P ^ 10.000 - n /
Here I must include the extra length assumed due to the reluctance outside
of the worldng air-gap.
128
ELECTROMAGNETS.
!■ P««Bds,
Aaiper«-tan Factor mt
L
P.
n
1
33.0
3600
2
28.3
3160
3
23.4
2800
4
19.2
2500
6
16.0
2200
6
13.8
1970
7
12.2
1760
8
11.0
1580
9
10.0
1400
10
9.2
1230
11
8.4
1100
12
7.8
1060
13
7.2
840
14
6.8
725
15
6.4
625
16
6.0
526
17
6.7
430
18
6.3
850
19
6.0
270
20
4.7
210
To approximate the curve of a plunser electromagnet at points bflhfi
le center of the winding, and the end of the wincunc where the phflj
enters, assume that the curve is a straight line for the last .4 of the i
tance: then the pull at any point, la as measured in inches, back from t
end ot the winding, will be
{t.
IN^
laP^ilN -n)
076,600 «» ' .4 L (10,000
-n))
where L equals length of the winding. In this it is assumed that the wind
is approximately as long as the inside of the frame.
In cases where a low density in the core is used, the curve for the in
clad solenoid effect cannot be calculated with so high a degree of aoenn
.//////f/////ff£f^^////{{£f/A
7//////////////M////^//^
r'f!^^:^^^::^^.^^T:y^.-T
zvu.'m^iimiLLM
FiOB. 2, 3, 4 and 5. Shapes of Electromagnets.
1
WINDING OF ELECTBOMAGNBTS. 129
i
POSITIONS INSIOS OF WIHDINe,(INCHES}
no. fl. OhuKotarlttliM ot El«ctri>m*fD*t*,
130
BLECTBOICAQNBTS.
^
^
)
Fig. 3 shows a simple ooll and planger and Fig. 4 the same magnet, but
with an iron jacket or return curoaii about the outside of the winding.
This is usually referred to as an iron-olad solenoid.
Bv placing a ** stop " inside the winding at the rear end of the frame
we hare the plunger electromagnet in Fig. 8.
It is to be obserred that the same coil and the same plunger are used in
each case. The cross section, A^ of the plunger is just 1 square inch.
Beferring to Fig. 8, curve "a" is due to the simple coil and plunger in
Fig. 2, and cunre ** 6 " is due to the iron-clad solenoid in Fig. 4. the ampere-
turns in the winding being 10,000 in all eases. It will be noticed that the
oiilv difference between curves ** a" and " fr " is that curve " 6 " is slightly
hiffher at distances greater than 6 in., owing to the confinement or the
field, and also that it bends upwiutl for short distances instead of falling
oif like curve " a.** This latter effect is due to the attraction between
the end of the plunger and the iron frame of the iron-olad solenoid. How-
ever, the pull throughout the eenter of the winding is the same in both
oases.
Where there is » hifl^ density of the lines of force in the plunger, aa
additional reluctance is in evidence, which
must be added to the length of the work-
ing air-gap.
The range of a solenoid is the distance
through wEich its plunger will perform
work when the wmding is ene(gised«
llie greater the length of the solenoid,
the greater will be the range, as the range
varies in nearly direct proportion witn
the length of the solenoid. The range of
the solenoid is constant regardless of the
ampere-turns, but Uie attraoti<m or pull
on the plunger varies directly with the
amxiere-tums after the core is saturated,
there being some variation below this
point due to change in the permeability
of the plunger.
In designing a solenoid, the pull should
be taken at a point on the curve which
is considerably below the maximum, as
this will allow for enough extra attraction
to overcome any friction, and also to keep
assuming a low point for the necessary pull,
greatly moreaseo.
AMWIW-TUIM*
Fio. 7. PuU due to Solencrfda of
Different Loigths with Plunger
1 sq. in. in Cross-Section.
the load moving, and by
the effective range will be
^
PROPERTIES OF WIRES AND CABLES.
RBTiaao BT Habold Pindbr, Ph.D.
Tax unit of resbtanoe now universally uaed ia the International Ohm.
Tbe following multiples of this unit are sometimes employed.
Megohm — 1,000.000 ohms,
lliorohm « 0.000,001 ohm.
The following table gives the value of the principal praotioal units of reeis-
taaee which existed pzevioai to the establishment of the International Units.
(
Unit.
International ohm . .
B, A. ohm
ohm
I's ohm ...
International
Ohm.
1.
0.0866
0.9072
0.9407
B.A.
Ohm.
1.0136
1.
1.0107
0.0536
Legal Ohm
1884.
1.0028
0.0804
1.
0.9434
Siemens's
Ohm.
1.0630
1.0600
1.
Ihtis to reduce British Association ohms to international ohms we divide
bv 1.0136. or multiply by 0.9866; and to reduce legal ohms to international
ohms we divide by 1.0028, or multiply by 0.9972, etc.
Lei
I
A
R
Sp«clllc ]|«alateMC«.
length of the conductor,
cross section of the conductor,
resistance of the conductor,
specific resistance of the conductor.
Then
or
R
I
'a*
If I is meafured In eentimeten and A in square oentlmeterB, p Is the
resistanoe of a centimeter cube of the oondnctor. If Ms measured in
iaehes and A in square inches, p is the resistance of an inch cube of the
eondoctor.
In tei^raph and telephone practice, speoiflo resistance Is sometimes
expressed as the weight per mi/e-oAm, wnicn is the weight In pounds of a
Mudiietor one mile long naving a resistance of one ohm.
Another oommon way of expressing speoiiic resistance Is in terms of
sAsif per milrfooi, i.e., the resiatance of a round wire one foot long and
QuQOi inch In mameter ; I is thenmeasured in feet and A in circular mils.
Xierohma per inch cube ■• 0.3887 X microhms per centimeter cube.
Ponnds per mile>ohm ■- 67.07 X microhms per centimeter cube X
speoiflo gravity.
Ohms per mil-foot » 6.016 X mlcrohma per cantimeter cube.
181
132
PROPERTIES OP CONDUCTORS.
ftpecMIc CoMdMCtiTftj U the reciprocal of speoifio renstanoe. It e ^
vpeofio oonductivity
I
^' RA'
1
c — -■
P
By RelatiTC ^r P«rceBtoc« CoMdnctlTltT' of a aample is meant
100 times the ratio of the conductivity of the sample at standard tant-
perature to the oonduotivity of a conductor of the same dimensions niade
of the standard material and at standard temperature. If Ao ib the specific
resistance of the sample at standard temperature and a* is the specific resist-
ance of the standard at standard tempw ature, then
Percentage conductivity — 100 —
Po
In comparing different materials, the specific resistanee should always
be determined at the standard temperature, which is usually taken aa 0"
Centigrade. If it is inconvenient to measure the resistance of the sample
at the standard temx>erature, this may be readily calculated if the tem-
perature coefficient a of the sample is known, i.e.,
l + o/
where pt ifl the specific resistance at temperature t.
]lffattlile«ieni*a Staadard of CoBdnctlvltj', which is the commercial
standard, is a copper wire having the following properties at the standard
temperature of Or C.
~ " 8.89.
1 meter.
1 gram.
.141729 ohms.
1.594 microhms per cubic centimeter.
100%. .
Specific gravity
Length
Weight
Resistance
Specific Resistance
Relative Conductivity
SpecUlc lteiiiiit»nc«. Relative RcMifaiteiic^, aad llelatlT«
Coadactl«'ity of Coadactom.
Referred to Matthiessen's Standard.
Resistanee in Microhms
at 0'
»C.
Relative
Relative
Metals:
Resis-
tance.
%
Conduc-
Centimeter
Cube.
Inch Cube.
tivity.
%
Silver, annealed . . .
1.47
.679
92.5
108.2
Copper "
1.65
.610
97.6
102.6
Copper (Matthiessen's
Standard).
1.594
.6276
100
100.0
Gold (99.9% pure)
2.20
.865
138
72.6
Ahimfniim (00% pnrft^
2.56
1.01
161
62.1
Zinc
5.75
2.26
362
27.6
Platinum, annealed . . .
8.98
3.63
665
17.7
Iron
9.07
3.67
670
17.6
Nickel
12.3
4.86
778
12. g
Tin
13.1
6.16
828
12.1
Lead
20.4
8.04
1.280
7.82
Antimony
35.2
13.9
2.210
4.53
Mercury
Bismutn
94.3
37.1
5,930
1.69
130.
61.2
8.220
1.22
Carbon (graphitic) . .
Carbon (arc light) . .
2.400-42,000
950-16.700
about 4.000
about 1,590
Selenium
6X10"
2.38 X10«
GENERAL.
133.
LdquidB»t 18<*C.
Ohms per Genti-
motor Cube.
Ohmii per Inch
Cube.
Pnreimtcr
2650
30
4.86
1.37
9.18
1.29
21.4
in.'tn
Sea water
11 R
Sulphmie acid, 5%
Snlpharie acid, 30%
Solphiiric add. 80%
Nitricadd, 30%
Zine solphate. 24%
1.93
.544
3.64
.512
8.54
VeatperAinr* C^eflident.
Tlie
doetor.
Let
reaistanoe of a conductor varies with Xhe temperature of the
con*
(
Ro " Reeietance at 0**.
R <- Resistance at (^.
R - iWl + a 0.
a is called tlie feinpemter« coefficient of the oonduotor. 100 a is the per-
eeatage change In resistance per d^ree change in temueratore.
The following ralues of the temperature coefficient naye been found for
temperatures measured in dozrees Centigrade and in degn^ees Fahrenheit.
It is to be noted that the coomoients yary considerably with the purity of
th» conductor.
Pure Metals.
Centigrade
Falirenhdt
a
Slyer, azmealed
Corner, annealed ....
G«WC».9%)
Ahuninium (99%) ....
SSm
^iDam, annealed . . .
IPOO
Nkkfli
0.00400
0.00428
0.00377
0.00423
0.00406
0.00247
0.00625
0.0062
0.00440
0.00411
0.00389
0.00072
0.00354
0.00222
0.00242
0.00210
0.00236
0.00226
0.00137
0.00347
0.00346
Tin . ;
0.00245
Lesd
^imony
Biansth
0.00228
0.00216
0.00044
0.00197
Matthieseen's formula for soft copper wire
R - Bo (1 + .00387* + .00000697^).
TIm wire used by Matthiessen.was as pure as could be obtained at the
tine (1^0), but in reality contained considerable impurities; the above
fecmnk, therefore, is not generallv applicable. Later experiments have
ihown that for all practical work the above equation for copper wire may
bsvritten . . «^
H - «b (1 + .00420 for « in • C.
PROPERTIES OF CONDUCTORS,
111
III
,ST1.S«
iU : § 1 : S
■iCiu«iD »gT»<lB
« o« : S S jr.
■tpoi annbg «!
S S?! : : : : :
*a ■loTM »Diir»n
S i§ i ; ; : :
HMJ3III low J»J
MM ; ; M
prfs^sas'H
IE. 4
17.4
20,0
27.8
76.6
qooiMdralvSoiM
s S3 2 a a s s
InnioiOTWOJIW
S !£8 S = S 3 .
J ELECTRICAL PROPERTIEa OF METALS. 135
^.^^oJJS^
s 8Si s ; g ; ;§ 1
s ;; !
■«)U«D ■>BF«»B
^ ™8 . ; , : iS s. ; ; ;
mill ! H
■mH°^P^
i=i; :! ; : 1 ilM;
-»a ■»««'d »«mi»H
S i^ : i i ; ii 11 ; M
ssrSlj
i ;^5 i ; ; ;3 P i ; : S
;a':,-sia.
„^»S%,
. ;:«s Is s s «! s§g§: S
« *-» - « ^ ^
"■niMOHI ■£>*»■.
.. . = s= s . ,» sss=s s
S 2|2 — ^ p -- »" -
■
1
jlr
Ml
k-Ji
tills
if
PBOPERTI£S OF CONDUCrOR8.
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PHYSICAL AND ELECTRICAL PROPERTIES OP METALB. 137
pmmi -ipoi SSI ■ i«==i S' 5 S S
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PHYSICAL AND ELECTRICAL PROPEBTIEB OF IfETAU. 139
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140
PROPERTIES OF CONDUCTORS.
O C4 C4 C«
CO CO CO CO
•X^IAWJO !>Sia»<Jg
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3 d d SQQfdaQ d d
WIRE GAUGES.
141
The naes of wir«s are ordinarily expressed by an arbitrary aeries of num-
Unfdrtunately there are several independent numbering methodB,
■0 that it » alwajrs necesaary to specify the method or wire gauge U8«l.
The following table gives the numbers and diameters in decimal parts of an
inch tar the various wire gauges used in this country and England.
Pttrta •#
Number
of
Wire
Onto.
Roebling or
Washburn
AMoens.
Brown A
Sharpe.
Birming-
ham, or
Stubs.
English
LegaTStand-
ard.
Old English*
or London.
ft^>
.400
• • V ■ • •
• • ■ ■
.464
5H>
.430
• ••■•■
• • a •
.432
• •••••
4-0
.393
.4600
.454
.400
.4540
^
.362
.4096
.425
.372
.4250
a^
.331
.3648
.380
.348
.3800
0
.307
.3249
.340
.824
.3400
1
.283
.2893
.300
.300
.3000
2
.263
.2576
.284
.276
.2840
8
.244
.2294
.259
.253
.2590
4
.225
.2043
.238
.232
.2380
5
.207
.1819
.220
.212
.2200
6
.192
.1620
.203
.192
.2030
7
.177
.1443
.180
.176
.1800
8
.162
.1285
.165
.160
.1660
9
.148
.1144
.148
.144
.1480
10
.135
.1019
.134
.128
.1340
U
.120
.09074
.120
.116
.1200
12
.105
.08081
.109
.104
.1090
13
.092
.07196
.095
.092
.0950
14
.080
.06408
.083
.080
.0830
15
.072
.05706
.072
.072
.0720
10
.063
.05082
.065
.064
.0650
17
.054
.04525
.058
.056
.0580
18
.047
.04030
.049
.048
.0490
19
.041
.08589
.042
.040
.0400
20
.035
.03196
.035
.036
.0350
21
.032
.02846
.032
.032
.0315
22
.028
.02534
.028
'.028
.0295
23
.025
.02257
.025
.024
.0270
24
.023
.02010
.022
.022
.0250
25
.020
.01790
.020
.020
.0230
36
.018
.01594
.018
.018
.0205
27
.017
.01419
.016
.0164
.01875
28
.016
.01264
.014
.0148
.01650
29
.015
.01125
.013
.0136
.01550
30
.014
.01002
.012
.0124
.01375
31
.0135
.00893
.010
.0116
.01225
32
.0130
.00795
.009
.0108
.01125
33
.0110
.00708
.008
.0100
.01025
34
.0100
.00630
.007
.0092
.0095
35
.0095
.00561
.005
.0084
.0090
38
.0090
.00500
.004
.0076
.0075
37
.0085
.00445
• • • •
.0068
.0065
38
.0080
.00397
• ■ • •
.0060
.0057
39
.0075
.00353
• ■ • •
.0052
.0050
40
.0070
.00314
• • • •
.0048
.0045
(
142
PROPERTIES OP CONDUCTORS.
_ »• — Used almost universally in this oountry for iron
and steel wire.
BrawM * BUaurpm €taMic«« — The American standard for wires for
eleotrical purposes.
BlnsBliBrliMM ChaoM. — Used largely in England and also in this
country for wires other than those made especially for eleotrical purposes,
ezoepting iron wire.
Saw of the Sro
)
The diameters of wires on the B. and S. gauoe are obtained from the
geometrio series in which No. 0000 — 0.4600 inch and No, 36 — .005 in.,
the nearest fourth significant figure being retained in the areas and diametera
so deduced.
Let
llien
n —
d-
gauge number (0000 -• - 3; 000 — - 2; 00 — — 1).
diameter of wire in inohes.
0.3249
1.128* *
Wires larger than No. 0000 B. and S. are seldom made solid but are
built up of a number of small wires into a strand. The group of wires is
called a "strand:" the term "wire" being reserved for the individual wires
of the strand. Strands are usually built up of wires of such a siie that the
cross section of the metal in the strand is the same as the cross section of a
soUd wire having the same gaug^ number.
If n — number of concentric layers around one central strandi
then
3 (n* + n) + 1 *. t metal area
(2n+l)a " ™**° *" available
The number of wires that will strand will be 8 n (n + 1) + !•
Number of Strands.
metal area
available area
1
7
19
37
61
91
1.000
.778
.760
.755
.753
.752
•lietttlilBflr Cor«. — The number, N, of sheathing wires
eter, d, which will cover a core having a diameter. D, is
having a diam-
COPP£B WIRE TABLES
143
of C«Bi
■••■clal Wlr«. — Aremc*
FwCcntConduetrnty (Matthieaaen's Standard 100)
Speoifie GraTity
Pbuadfl in 1 cubic foot
IVMiiidi in 1 cubic inch
Pbunds per mile per careular mil
Ultimate Strength
eq. m.
lb. X in.
Modnius of Elasticity
in. X sq. in.
Cbefficient of Linear Expansion per •C
Cbeffident of Linear Expannon per * F.
Mdtins Point in*C .,.,.
luting P6int in * F. .*
Spedfie Heat (wafct-«eoonda to heat 1 lb. 1** C.) . .
IbsoMl Conductivity (watte through cu. in., tem-
perature gradient 1** C.)
IGoohme per centimeter cube 0^ C
IGaohmfl per inch cube 0^ C. . .
Ofams per nul-foot 0^ 0
Ohms per mil-foot 20^ C
Rerifltanoe per mile O' C
Bcsistanoe per mile 20^ C. .
^nods per mile ohm 0^ C. .
Pounds per mile ohm 20*' C. .
Tompvature Coefficient per ** C.
T«nperature Coefficient per ^ F.
• • • •
• ••••••
Annealed.
100
8.9
555
.321
.0160
23.000
• ••••«••
.0000171
.0000095
1060
1920
176
8.7
1.594
.6276
9.59
10.36
50.600
cir. mils.
54.600
cir. mils.
810
875
.0042
.00233
Hard.
98
8.94
558
.323
.0161
55,000
16,000.000
.0000171
.0000095
1060
1920
176
8.7
1.626
.6401
9.78
10.67
51.600
cir. mils.
55,700
cir. mils.
830
896
.0042
.00233
(
144
PROPERTIES OF CONDUCTORS.
•peclllc ^wwtltlM of Varlew
•f C:«pper wtOi
SubstanoQB alloyed with Pure Copper.
Carbon:
Copper with
Sulphur:
Copper, with
PhoephoniB:
Copper, with
Copper, with
Copper, with
Araenio:
Copper, with
Copper, with
Copper, with
Zinc:
Copper, with
Copper, with
Copper, with
Iron:
Copper, with
Copper, with
.05 per cent of carbon . .
. 18 per cent of sulphur . .
. IS per cent of phosphonia
.96 per cent of phosphonu
2.6 per cent of phoephoruB
traces of arsenic ....
2.8 per cent of arsenic . .
6.4 per cent of arsenic . .
traces of line
1 .6 per cent of sine . .
3.2 per cent of sine . .
.48 per cent of iron . .
1 .06 per cent of iron . .
1 .33 per cent of tin .
2.52 per cent of tin .
4.9 per cent of tin . .
Tin:
Copper, with
Copper, with
Copper, with
Silver:
Copper, with
Copper, with
Gold:
Copper, with 3.5 per cent of gold . .
1 . 22 per cent of silver
2.45 per cent of silver
Aluminum:
Copper, with
Conducting
Power of
Hard -drawn
AUoy. Pure
Soft Copper
being 100.
. 10 per cent of aluminum
77.87
92.06
70.34
24.16
7.62
60.08
13.66
6.42
88.41
79.37
69.23
35.92
28.01
60.44
33.93
20.24
90.34
82.52
67.94
12.68
Temperature
Centigrade.
18.3
19.4
20.0
22.1
17.5
19.7
19.3
16.8
19.0
16.8
10.3
11.2
13.1
16.8
17.1
14.4
20.7
19.7
18.1
14.0
COPPER WIRE TABLES. 145
Below are ^ven the Oopper Wire Tables of the American Institute of
Beetricsl fiigmeers. The table for the Brown and Sharpe sauce is derived
from the following fonnulas:
Lei A — wire gauge number.
d "■ diamet,er of wire in inches.
C.1C ■" area in dreular mils.
r — reeiatanoe in ohms per 1000 feet at 20* G.
m — weight in pounds per 1000 feet.
0.3240
Vm d —
CM. ^
1.123"
105.500
B
1.261*
r - 0.09811 X 1.261*
810.5
• " 1.261*
A uKfoI approximate formula for resistance per 1000 feet at about 20* C.
r - 0.1 X 2*. {^ - 1.26; 2t - 1.5o).
Fnim this it is seen that an increase of 3 in the wire number corresponds
to donbfing the resistance and halving the cross section and weight. Also,
that aa increase of 10 in the wire number increases the resistance 10 times
and diminiahes the oroes section and weight to ^th Uxeir original values.
Tbe data in the following table has been computed as follows : Mat-
thictsen'a standard resistivity, Matthiessen's temperature coe£Bcient, specific
. fitvityof copper --S^. lusistanoe in terms <» the international ohm.
MattUesien's standard 1' meter gramme of hard drawn copper— 0.1469
B.A.U. a <P C. Ratio of resistivity hard to soft oopper 1 .0226.
Matthiessen's standard 1 meter sramme of soft drawn copper— 0.14366
BXU. @ OP C. One BJL.U. - OiMW international ohm.
MtrthJiesBen's standard 1 meter gramme of soft drawn copper— 0.141729
iatenational ohm at HP G.
Ttmperature coefBcients of resistance for 20^ 0., 60^ G., and W* G., 1.07968.
1J«5 and 1.33681 respectively. 1 foot -6.3048028 meter, 1 pound - 453.50266
SnauBfli.
Althongh the entries in the table are carried to the fourth significant
j!«>t, the eompaUtions have been carried to at least five figures. The last
jVkii therefore correct to within half a unit, representingan arithmetical
^cp«e of aceuracv of at least one part in two thousand. The diameters of
»«B.» 8. or A. W. G. wires are obtained from the geometrical series in
vbiek No. 0000=0.4600 Inch and No. 36 = 0.006 inch, the nearest fourth sig-
Bileaat digit being retained in the areas and diameters so reduced.
It a to he observed that while Matthiessen's standard of resistivity may
Be panoanently reoogniaed, the temperature coefficient of its variation
vbkh he Introduoed, and which is here used, may in future undergo slight
ItllliML
(
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146
PB0PBBTIB8 OF CONDUCTOB8.
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COPPER WIRE TABLES.
147
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PBOPEBTIE8 OF 0ONDUCTOB8.
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COPPER WIRE TABUBB.
140
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PROPEBTIES OF CONDUCTOB8.
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COPPER WIRE TABLES.
151
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Il
111
FBOFBltTlES OF CONDUCTORS.
I
It!
Ill t
COPPER WIRE TABLES. Ibi
Si §9Slii sSP^S SSiS^ 8«88« eeoA^
■5 sSsfifi nSs^s 885fis qZSSs Sfis«*5
99 fiOOvO 000*^*^ *^99C9& 09C«wCl 2Q9^*0
»e oeooo cSeooe oSeeo oooo<S SnSiiaS
»eooe oeoeo eoeeo eoeeo oeo
s;
Crfi^noS eSv^Sio^o lo^oMO e»e9ion
oo oeooo ooooo ooooo ooeoo ooooo
bS s^ssS SSS9S S&ssa XH^ssfi s^ssssr?
I 89 fi09**9 OxvvO vSO^fi^ O^es^^S trs^^'^t'
SS SSfififi SSS9S SSS9S9 xSxSss S!*^S3SX
33 **53^ SR^^o 9$«?99 o.S^^I *in*1"t^
I oo ooeeo ooooo ooooo odooo ooooo
SS 8§2*** SS-4e«A o
ll iiiSS ^^M% |25?5;? Scjcoc,-, «?^^«-.
oo doodo oo-«^ «^SSSil SSggg ||?J|
si lii^^ iiSSI ^Ssjjss ^s
SS S55-« ».SS9^S «^:85^^ «o^oq«)^ "^^i^^^
oo oeooo oo^«rf »«SSa8 S8838 88SS8
»H »-i 55 Z oS "I'^wi
o^ iiiii i§|S^ %^^M s88oo «^^
I O© e€>dOG» od-.«« "ooo^gg ^8Sg| Sg§S8
* • ^
'S= S5SSS &S$S8S3 882^298 ^888;; SS8$88
f
154
PROPERTIES OP CONDUCTORS.
The following oondenBed copper wire tables for both solid and stranded
conductors are more convenient tor ordinary calctilations.
Aolld Copper ITIre.
No.
B.A8.
Diam.
Mils.
Area,
ar. Mils.
Weight. Pounds.
Resistance. 20® C.
Bare.
1000'.
Mile.
Feet
per
Pound.
1000*.
Mile.
0000
000
00
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
460
409.6
364.8
324.9
289.3
257.6
229.4
204.3
181.9
162.0
144.3
128.5
114.4
101.9
90.74
80.81
71.96
64.08
57.07
50.82
45.26
40.30
35.89
31.96
211,600
167,800
133,100
105,500
83.690
66.370
52.630
41,740
33.100
26.250
20,820
16,510
13,090
10.380
8.234
6,530
5.178
4.107
3.257
2,583
2.048
1.624
1,288
1,022
640.5
508
402.8
319.5
253.3
200.9
159.3
126.4
100.2
79.46
63.02
49.98
39.63
31.43
24.93
19.77
15.68
12.43
9.858
7.818
6.200
4.917
3.899
3.092
8,381
2,6^2
2,127
1,687
1,337
1,062
841.1
667.4
529.0
419.5
332.7
263.9
209.2
166.0
131.6
104.4
82.79
65.63
52.05
41.28
32.74
25.96
20.59
16.33
1.561
1.969
2.482
3.130
3.947
4.977
6.276
7.914
9.980
12.580
15.87
20.01
25.23
31.82
40.12
50.59
63.79
80.44
101.4
127.9
161.3
203.4
256.5
323.4
.04893
.06170
.07780
.09811
.12370
.1560
.1967
.2480
.3128
.3944
.4973
.6271
.7908
.9972
1.257
1.586
2.000
2.521
3.179
4.009
5.055
6.374
8.038
10.14
.2583
.3258
.4108
.6180
.€631
.8237
1.0386
1.3094
1.0516
2.0824
2.6257
3.3111
4.1754
5.2652
6.6370
8.374
10.560
13.311
16.785
21.168
28.690
33.655
42.440
53.540
STRANDED COPPER WIRE.
155
No.
Diam.
Mils.
Ar«a
Weight PoundB.
Reflistanee 20** G.
68* F.
B^8.
Or. Mils.
Bare.
LOOO*.
Per
MUe.
Feet
per lb.
1,000'.
Bflle.
1.500.000
4.575
24.156
.219
.006902
.03644
1.250.000
3.813
20.132
.262
.008282
.04373
1.152
1.000.000
3.050
16.104
.328
.010353
.05466
1.125
050.000
2,808
15,200
.345
.010900
.05755
1.002
000.000
2,745
14.404
.364
.01150
.06072
1.062
850.000
2.503
13.688
.385
.01218
.06431
1.036
800,000
2.440
12.883
.409
.01294
.06832
090
750.000
2.288
12.078
.437
.01380
.07286
963
700.000
2.135
11,273
.468
.01479
.07809
027
650.000
1,083
10.468
.504
.01593
.08411
801
000.000
1.830
0.662
.546
.01725
.09108
855
550.000
1.678
8.857
.596
.01882
.09937
810
500.000
1,525
8,052
.655
.02070
.10930
770
450.000
1.373
7,247
.728
.02300
.12144
728
400.000
1.220
6.442
.819
.02588
.13664
670
350.000
1.068
5.636
.936
.02958
.15618
630
300.000
015
4.831
1.003
.03451
.18221
590
250.000
762
4.026
1.312
• .04141
.21864
OOQO
530
211.600
645
3.405
1.560
.04893
.2583
ooo
470
167,800
518
2.700
1.049
.06170
.3258
00
420
133.100
406
2.144
2.463
.07780
.4108
0
375
105^500
322
1.700
3.106
.09811
.5180
1
330
83.600
255
1,347
3.941
.12370
.6531
8
201
66.370
203
1,072
4.926
.15600
.8237
s
261
52.630
160
845
6.250
.19670
1.0386
4
231
41.740
127
671
7.874
.2480
1.3094
Tlw table ia oalculsted for untwisted strands; if the strand is twisted the
erooi section of the copper at right angles to the length of the strand, the
vciiht per unit length and the resistance per unit length will each increase
&tn& 1 to 3 per cent, and the length per unit weight will decrease from 1 to 8
per eent, depending on the number of twists per unit length and the number
a vires in the stzmiid.
(
156
PROPERTIES OF CONDUCTORS.
Teaalle AtreBgtb of Copper Wlre«
ROBBLINO.
Numbera,
B.ftS.
Gauge.
Breaking Weight, Lbs.
Numbers.
B.&8.
Gauge.
Breaking Weight. Lba.
Hard-
drawn.
Annealed.
Hard-
drawn.
Annealed.
0000
000
00
0
1
2
3
4
5
6
7
8
8.810
6.580
5.226
4,558
3.746
3,127
2.480
1.967
1.559
1,237
980
778
5,650
4,480
3.553
2.818
2.234
1,772
1,405
1,114
883
700
555
440
9
10
11
12
13
14
15
16
17
18
19
20
617
489
388
307
244
193
153
133
97
77
61
48
340
277
210
174
138
100
87
60
65
43
34
27
The strength of soft copper wire varies from 32.000 to 36,000 pounds per
square inch, and of hard copper wire from 45,000 to 68,000 pounds per
square inch, according to the degree of hardness.
The above table is calculated for 34,000 pounds for soft wire and 60,000
pounds for hard wire, except for some of the larger sises, where the breaking
weight per square inch is taken at 50.000 poxmds for 0000, 000, aiMl 00,
65.000 for 0, and 57,000 pounds for 1.
n«HI.]»ni
Copper
ROEBLXNO
Siie
Resistance
Breaking
Weight
Furnished
in Coils
as follows,
HUes.
Approx. Sise
E.B.B. Iron Wire
Equal to Copper.
Dm Ob D.
Gauge.
in Ohms
per Mile.
Strength,
Pounds.
]^L
9
4.30
625
209
1
2 .
10
5.40
525
166
1.2
3
11
6.90
420
131
.52
4
12
8.70
330
104
.65
6
Iron-Wire
13
10.90
270
83
1.20
64
Qmagp,
14
13.70
213
66
1.50
8
15
17.40
170
52
2.00
9
16
22.10
130
41
1.20
10 ^
In handling this wire the sreatest care should be observed to avoid kinks,
bends, scratches, or outs. Joints should be made only with Mclntire Con-
nectors.
On account of its conductivity being about five times that of E2x. B. B.
Iron Wire, and its breaking strength over three times its weight per mile,
copper may be used of wUon the section is smaller and the weight less than
an equivalent iron wire, allowing a greater number of wires to be strung on
the poles.
Besides this advantage, the reduction of section materially decreases the
electrostatic capacity, while its non-magnetic character lessens the self-induc-
tion of the line, both of which features tend to increase the possible speed of
signalling in telegraphing, and to eive greater clearness of enunciation over
telephone lines, especially those of great length.
WEIGHT OF COPPER WIRES.
157
ITelirlk* ^ C«9per Wire.
Eiraunc Stbtbm, pbb 1,000 Fsbt and per Mils, in Pounds.
Boglieh Legal
Standard.
Birmingham.
Brown A Sharpe.
«
Weiffht.
inBfils.
Weight.
Diameter
in Mils.
Weight.
i
7i
1000
Feet.
MUe.
1000
Feet.
Mile.
1000
Feet.
Mile.
6-0
404
432
400
052
565
484
3,441
2,983
2.557
fi-0
4-0
454
624'"
ai,294
• • ■ • •
460
64i"* ■
3,'38i2""
W)
372
419
2,212
425
547
2,887
410
509
2.687
2^348
367
1,935
380
437
2308
365
403
2.129
0324
318
1.678
340
350
1,847
325
320
1.688
1
300
272
1,438
300
272
1,438
289
253
1.335
2
270
231
1,217
284
244
1,289
268
202
1.064
8
252
192
1.015
250
203
1,072
229
159
838
4
232
163
800
238
171
905
204
126
666
5
212
130
718
220
146
773
182
100
529
6
102
112
589
203
125
659
162
79
419
7
178
94
496
180
98
518
144
63
331
8100
77
409
165
82
435
128
50
262
0
144
63
331
148
66
350
114
30
208
10
12S
50
262
134
54
287
102
32
166
11
116
41
215
120
44
230
01
25
132
}?W>*
33
173
100
86
100
81
20
105
13
02
25.6
135
96
27.3
144
72
15.7
83
14
80
19.4
102
83
20.8
110
64
12.4
65
15
72
15.7
83
72
15.7
83
57
9.8
52
16
64
12.4
65
65
12.8
68
51
7.9
42
17
56
9.5
50
58
10.2
54
45
6.1
32
18
4S
7.0
36.8
49
7.3
38.4
40
4.8
25.6
10
40
4.8
25.6
42
5.3
28.2
36
3.0
20.7
20
38
3.9
20.7
35
3.7
19.6
32
3.1
16.4
31
32
3.1
16.4
32
3.1
16.4
28.5
2.5
13.0
21
33
2.4
12.5
28
2.4
12.5
25.3
1.9
10.2
23
24
1.7
9.2
25
1.9
10.0
22.6
1.5
8.2
24
22
1.5
7.7
22
1.5
7.7
20.1
1.2
6.5
25
30
1.2
6.4
20
1.2
6.4
17.9
.97
5.1
2S
18
.98
5.2
18
.98
5.2
15.9
.77
4.0
27
16.4
.81
4.3
16
.77
4.1
14.2
.61
3.2
2S
14.8
.66
3.5
14
.59
3.1
12.6
.48
2.5
20
13.6
.66
3.0
13
.51
2.7
11.3
.39
2.0
30
31
12.4
.47
2.5
12
.44
2.3
10.0
.30
1.6
11.6
.41
2.15
10
.30
1.6
8.9
.24
1.27
32
10.8
.35
1.86
9
.25
1.3
8.0
.19
1.02
33
10.0
.30
1.60
8
.19
1.02
7.1
.15
.81
34
0.2
.26
1.35
7
.15
.78
6.3
.12
.63
35
8.4
.21
1.13
5
'.075
.40
5.6
.095
.50
36
7.6
.17
.02
4
.048
.256
5.0
.076
.40
i
(
The dJameten giren for the yarlons sizes are those to which the wire is
Mtoally drawn.
158
PB0PERTIE8 OP CONDUCTORS.
•f Copper Wli««
Mmsic Stbtbm — Per Kzlouetbr, in Kilooraiu.
Number
of Wire
Gauge.
Roebliog.
Brown A
Sharpe.
Birmingham
or Stubs.
Legal
Standard.
e-0
954.3
• • • •
970.9
6-0
833.9
• « « • •
• • • • •
841.6
4-0
696.6
954.3
929.4
721.6
8-0
691.0
756.8
814.6
624.0
:m)
494.1
600.2
651.3
646.2
0
425.1
480.4
621.3
473.4
1
361.2
877.4
405.8
406.8
2
311.9
^99.3
363.3
843.5
8
268.6
237.4
302.6
286.3
4
228.3
188.3
256.3
242.7
5
193.2
149.3
218.3
202.7
6
166.2
118.4
185.9
166.2
7
141.3
93.9
146.1
139.7
8
118.3
74.5
122.8
116.4
9
98.8
69.0
98.8
93.6
10
82.2
46.8
81.0
73.9
11
64.9
37.1
64.9
60.7
12
49.9
29.5
63.6
48.8
13
38.2
23.4
39.8
38.2
14
28.9
18.6
31.1
28.9
15
23.4
14.7
23.4
23.4
16
17.9
11.7
19.1
18.6
17
13.2
9.23
15.2
14.1
18
9.96
7.32
10.8
10.4
19
7.68
6.80
7.95
7.22
20
6.52
4.61
6.52
6.85
21
4.61
3.65
4.62
4.61
22
3.54
2.89
3.64
3.64
23
2.81
2.16
2.81
2.59
24
2.38
1.82
2.19
2.19
25
1.80
1.44
1.80
1.80
26
1.46
1.16
1.46
1.46
27
1.80
.908
1.16
1.21
28
1.16
. .720
.884
.988
29
1.02
.672
.762
.833
30
.884
.462
.649
.694
81
.822
.359
.461
.607
82
.762
.284
.365
.625
88
.644
.226
.289
.461
84
.461
.179
.220
.881
86
.406
.141
.113
.819
86
.365
.113
.071
.260
STANDARD COPPEB STBANDS.
159
ROKBUNO.
CJL
Wiraa.
Outride
Diam.
Weisht
Ibfl.per
lOOOft.
No.
Sise.
2.000.000
1,990.000
1.900.000
127
127
127
.1255
.1239
.1223
1.632
1.611
1.590
6100
5948
5796
135O.O0O
IJKOfiOO
1,7504)00
127
127
127
.1207
.1191
.1174
1.560
1.548
1.526
5643
5490
5338
1.700.000
MGO.00O
1.600.000
01
91
91
.1867
.1347
.1326
1.504
1.482
1.450
5185
5083
4880
1.650,000
1.500,000
1.450,000
91
91
91
.1305
.1284
.1262
1.436
1.412
1.388
4728
4575
4423
1.400,000
1350.000
1.300.00O
91
91
91
.1240
.1218
.1196
1.364
1.340
1.315
4270
4118
3965
l;2SD,U0O
1.200,000
1.150.000
01
61
61
.1178
.1403
.1878
1.289
1.263
1.236
3818
3660
3508
I.IOOXXX)
14UOJ00O
1.000,000
61
61
61
.1343
.1312
.1280
1.209
1.181
1.152
3355
3203
3050
950.000
9Q04M)0
860,000
61
61
61 .
.1247
.1214
.1180
1.122
1.093
1.062
2898
2745
2593
800.000
750,000
7004)00
61
61
61
.1145
.1108
.1071
1.031
.997
.964
2440
2288
2135
6604)00
6004)00
6504X)O
61
61
61
.1032
.0091
.0949
.929
.892
.854
1988
1830
1678
500.000
460,000
400.000
61
37
37
.0905
.1103
.1039
.815
.772
.727
1525
1373
1220
960.000
900,000
2504)00
37
87
37
.0972
.0900
.0821
.680
.680
.575
1068
915
763
r/
160
/
PROPERTIES OF CONDUCTORS.
AtaiidAMl Copper Stnuids. — (Con^tntMd).
ROXBUNO.
SiM.
D% &. S*
Wires.
No.
0000
000
00
10
10
10
.1055
.0041
.0837
0
1
2
10
10
7
.0746
.0663
.0075
8
4
5
7
7
7
.0866
.0771
.0688
6
8
10
7
7
7
.0612
.0484
.0386
12
14
16
7
7
7
.0306
.0242
.0103
18
7
.0151
Site.
OuUide
Diameter.
Weisht.
Lbs. per
1000 ft?
.528
.471
.410
645
513
406
.873
.832
.293
322
255
203
.260
.231
.206
160
127
101
.184
.145
.116
80
50
32
.002
.073
.068
20
12
8
.045
5
IVeailMr-proof Use amd Homo fTlre. Aolid C«bA«<
Standard Undbrqround Cabls Co.
B. dc S.
Gauge.
0000
000
00
0
1
2
8
4
5
6
7
8
0
10
11
12
14
16
18
20
Double Covered.
Lbs. per
MUe.
3690
2070
2300
1860
1500
1225
080
800
640
520
420
345
275
235
100
145
105
80
55
42
IAm. per
1000 ft.
600
562
452
352
284
232
186
151
121
08
70
65
52
45
36
27
20
15
10
8
Triple Covered.
Diam. in
MUs.
725
655
585
545
505
470
385
360
335
300
270
245
225
105
180
165
140
130
125
122
Lbs. per
Mile.
3010
3160
2560
2020
1650
1340
1050
860
700
575
465
300
320
265
226
180
130
100
80
68
Lbs. per
1000 ft.
741
508
485
382
312
254
100
163
132
100
88
74
60
50
42
34
24
10
15
12
Diaxn. in
Mils.
780
700
635
590
550
515
450
430
400
360
335
265
255
220
205
185
160
150
145
135
RUBBER COVERED WIRES AND CABLES. 161
17a««rwvMem' T«st of Sablier Govered Wir»«
Adopted Dec 6, 1904,
Tlie ISectrieftl Cominittee of the Underwriten National ABBooiation
rMoamiended the foUowinc, which was adopted.
Each foot of the completed oovering muat show a dielectric strength
■ofBcieat to resist throughout five minutes the application of an electro*
motive force proportionate to the thickness of msulation in aiooordanoe
with the following table:
Tliieknesi Breakdown Test
m 64ths indico. on 1 Foot.
1 8,000 Volts A. C.
2. . . 6,000 " "
3 9,000 "
4 ii,oo6 ••
6 13,000 "
fl 16,000 " ••
7 16,600 •• ••
8 18,000 " ••
10 21,000 •• ••
12 23,600 " ••
14 26,000 " "
16 28.000 " ••
I
nl livbber Corered ITlrea and Cables.
(Made by General Electric Company.)
Bnbber covered wires and cables are insulated with two or more coats of
Tobber, the inner ooat in all cases being free from sulphur or other sub-
rtance liable to corrode the copper, the best grade of nne Para being em-
plored. All conductors are heavily and evenlv tinned.
nve distinct finishes can be furnished as follows: — White or black braid,
phdn lead jacket, lead Jacket protected by a double wrap of asphalted Jute,
lead jacket armored with a special steel tape, white armored, for submarine
For use in conduits the plain lead covering is recommended, or if corro-
iU>B is especially to be feared, the lead and asphalt. For use where no con-
dvit is available, the band steel armored cable is best, as it combines
moderate fleadblUty with great mechanical strength, enabling it to resist
treatment which would destroy an unarmored cable.
Id addition to the ordinary galvanometer tests, wires and cables are
teited with an alternating current (as specified in table) before shipping.
.Special rubber covered wire and cable with lead jackets will be covered
viththe following thicknesses of lead unless otherwise specified:
Outside diameter of cable (inside diameter of lead pipe).
Up to and including . 600* A'
JiOl'to .reO*. inclusive h'
.751' to 1.250', inclusive h'
1.26rtol^. inclusive ... A'
Larger than 1.501' i'
PROPERTIES OF CONDUCTORS.
HatioBal HBctPtc Cml«,
Si«.
1
-?
t"
1.
J
f
i
7^S^
B. * 3.
II
ll
n
ll
IS
IM
20
33
170
253
A
ft
.000
ISOO
i«
190
35
40
203
284
ft
ft
IMXI
1500
H
ao3
33
47
220
397
ft
ft
i<m
IfiOO
12
230
43
58
213
314
ft
ft
1000
IJSOO
10
Ml
58
74
273
335
ft
ft
1000
ISOO
B
ZBB
81
99
318
3S3
ft
ft
1000
IGOO
6
M3
130
lao
389
411
ft
A
sow
2500
e
372
159
ISO
433
431
ft
A
woo
2500
- 4
3M
187
210
476
453
ft
A
2000
2500
9
*I9
830
254
538
478
ft
A
3000
2500
3
448
273
298
599
507
ft
A
aw
3600
1
540
362
390
722
670
ft
ft
2600
3900
0
576
438
«7
981
636
A
ft
25«)
3500
00
eie
633
582
1116
675
A
ft
25m
3500
000
961
648
678
.279
721
A
A
2500
3500
0000
711
7B4
R27
1473
771
A
ft
250O
3500
ohl* Ho. 1 B. A 8 uid la
«r ofdou
ir diunatar of doubls
BCBBEB IHSULATBD WIBSS AND CABLES.
Sa.
II
loft.
b*.
11
B.*9 ud
li
1
I
u
1
l«
.196
38
43
210
.ai2
3S
50
30
4S
63
258
33
10
s
.355
.2SS
aa
86
107
162
2S8
410
34
37
43
fi
.3»a
las
IS9
4S5
45
.423
1B7
321
48
240
365
507
60
280
316
639
54
.587
S81
935
loom
.eia
M7
478
1030
67
.6M
403
loss
68
laooo
.OH
513
1138
563
£96
1303
T
liOMO
.am
1278
OOO
.721
BS3
smn
8W
834
1532
82
.779
83S
809
1583
S3
KmoD
.873
1032
WOOOO
.1)32
1218
1283
2303
01
UOODO
1449
2527
««wo
sooooo
1.037
161S
1958
3203
IS
momo
3725
2S
MOOT
1,384
2619
4148
TSXW
I.32S
3791
2S80
4365
wxno
39G9
30S1
4912
4
mnco
1.423
339S
looono
1.482
3631
3721
IBOOM
1.650
449S
4600
7704
8
IWOOO
5433
8754
94
WOOOO
1.W2
0958
7075
10821
3S0
^
>
1000
306
325
g
1
1000
1000
379
1
1000
433
3000
405
sooo
481
aooo
609
3000
i
2000
3S00
676
2500
686
2600
716
2600
730
2600
i
2500
823
2600
839
948
4000
008
103
^
4000
188
4000
298
1
5000
430
6000
580
i
i
SOOO
820
1
5000
942
SOOO
163
*
5000
ir diamMer of doubl*
J
164
PROPERTIES OF CONDTTCTORS.
TVT P&
n«ctrlc CoaiiMuij It
Cable (^' livbber).
(iJBi. — Rbd Cobb, 2500 VoLim; Wbitb Cobb, 3000 Voias.
ix>B 30 Miinrra&
Wire.
SiM.
B. A. S«
I
16
14
12
10
8
Diametw,
.221
.234
.251
.272
.209
Weight
per 1000 ft.
in Lbs.
odA
83
40
51
67
91
.2 .
48
56
67
85
100
233
249
273
305
.315
.328
.845
.366
.803
li
§
i:
Insulatioin
ReBiotanoBin
MeeohtDS
perllile.
Red
Core.
350
850
850
860
860
Whita
000
600
600
600
eoo
Cable.
16
.227
39
56
242
.326
^
800
600
14
.248
43
61
260
.337
A
350
600
12
.262
60
80
285
.356
A
850
600
10
.286
78
99
316
.380
A
350
600
8
.816
106
127
360
.395
A
860
600
NoTB. — Add -in* to lingle braid for diameter of double braid*
RUBBER INSULATED WIRES AND CABLES.
— Rmd Cobk, 600O Vovn; WoiTa Oobb, 0000 Voun,
Sb>.
Diuiats,
p«lC&Oft.
P.
1_
4
3
B.A8.ud
S
pwMil*.
C.H.
n
I
ss.
^^
.396
81
80
zea
870
^
400
~700
313
78
93
31S
303
3M
90
400
700
381
116
138
396
400
414
103
177
467
474
434
181
498
494
eoo
400
S3«
646
610
300
eoo
481
203
SSO
flOS
041
i
360
S40
313
340
S74
609
eoo
403
013
8S3
860
000
007
44B
478
103S
■07
f
360
00
947
643
300
600
OOO
aei
OM
1323
300
GOO
OODO
743
800
841
1619
803
A
800
GOD
.300
00
91
304
'Z
400
700
324
332
400
700
368
103
120
307
427
400
700
308
131
156
410
457
7»
430
4SG
49S
700
468
203
229
S28
618
360
800
484
339
see
683
G23
360
642
000
830
305
878
834
iV
380
000
018
409
438
900
678
^
360
047
467
498
1084 .
600
007
480
360
000
687
062
G0«
1183
747
300
600
701
686
618
1255
761
300
731
638
1339
300
600
752
709
748
1430
812
t
300
600
7W
820
861
16W
864
300
,
810
804
900
1043
870
lV
300
600
Br of double brv<l-
166
PROPERTIES OF CONDUCTORS.
(A
//
Tbvt PBsee
UBB. — Rbd Cork, 7500 Volts ; Whttb Cobb, 9000 V01.TB,
roB 30 Minutes.
I. Wire.
Sue.
B. 9 S.
14
12
10
8
6
5
4
3
2
1
0
00
000
0000
.379
.396
.417
.444
.477
.527
.549
.572
.603
.634
.670
.710
.756
.805
Weight
per IWX) ft.
in lbs.
.£73
18
84
98
117
144
186
224
259
300
351
414
493
591
712
859
J2 .
106
121
141
169
213
252
287
329
380
445
525
625
746
895
•
372
398
432
479
547
583
635
852
933
1028
1142
1282
1450
1649
I
.438
.455
.478
.503
.536
.568
.578
.833
.663
.604
.730
.770
.815
.865
II
.az-
A
A
A
A
A
A
A
it
it
A
A
Insulation
Reaifltanoe in
Megohms
per Mile.
Red
Core.
White
Core.
600
1000
600
1000
600
1000
600
1000
550
900
550
900
550
000
550
900
550
900
550
900
500
800
300
800
300
800
300
800
BUBBEB INSULATED WIRES AND CABLES.
tHamwml Mtoetoto «J*npwv JBalikMr M— l«f< CMI
I FtMmtjam. — Bbd Cobb. 7500 Voltb ; Wnini Cobb, QOOO
u
373
447
^
BOO
401
4M
BOO
t
600
401
S30
900
ses
568
J
660
eos
580
821
e3«
S60
S96
eos
660
B81
<W7
560
1104
741
560
110S
770
660
7S0
1290
810
600
laM
SM
600
1443
IMS
875
BOO
1939
MS
600
leST
064
2178 1
031
400
2444 1
070
400
2872 1
3901 1
104
400
33M 1
2E1
360
329
4222 1
401
■
47S1 I
460
300 i
S012 1
498
300 1
6432 1
661
300
5852 I
630
300
SatM, — Aild ^ to sDcia braid (or diuoMar of doubla braid.
168
PROPERTIES OF CONDUCTORS.
Tnr pRjBflBuiiB. —
Cable ({k' RiaM»er).
Rbd Cobs, 12,000 Voi/»; Whitb Cobb, 16.000
VoxAB, FOB 30 Mznutbb.
L Solid.
Sise.
B. A S*
14
12
10
8
6
5
4
8
2
1
0
00
000
0000
.534
.551
.672
.598
.682
.652
.674
.609
.728
.750
.795
.860
.805
.945
WeUcht
per 1000 ft.
ID lbs.
£-6
OQPQ
156
173
196
226
272
302
340
386
441
509
592
696
851
1011
O u
184
201
224
255
303
833
372
419
474
643
638
732
926
1084
IJS
512
540
736
792
872
924
982
1053
1137
1235
1356
1708
1898
2109
\^
.562
.680
.eoi
.668
.692
.712
.734
.759
.788
.819
.855
.926
.971
1.021
a
A
h
A
A
A
A
A
Insulation
ResiBtance in
Mogoluna
per Mile.
Red
Core.
700
700
700
700
700
600
600
600
600
600
560
550
550
550
White
Core.
1200
1200
1200
1200
1300
1100
1100
1100
1100
1100
1000
1000
1000
1000
BUBBER INSTJLATBD WIRES AND CABLES.
169
Kleotaic Crnmtpmmj MnM^r Mmmlmtmd. IfTIre
(A' IftaMwr) — QmUnued.
II. Stranded.
B. k S. and
CM.
14
12
10
8
6
6
4
3
2
1
lOOOOO
0
126000
00
ISOOOO
000
200000
0000
250000
aooooo
350000
400000
fiOOOOO
0OOOOO
700000
760000
800000
900000
lOOOOOO
Diameter, Single
Braid. Inches.
Weight
per 1000 ft.
in lbs.
Double
Braid.
.543
162
190
.562
181
209
.586
205
233
.616
239
268
.654
200
820
.676
323
354
.702
366
397
.730
413
447
.762
472
506
.806
555
591
.850
619
656
.860
637
676
.800
708
759
.904
780
844
.924
838
903
.965
915
981
.997
1042
1110
1.013
1083
1151
1.060
1225
1294
1.119
1424
1404
1.167
1600
1675
1.213
1781
1860
1.300
2138
2226
1.378
2407
2589
1.450
2854
2950
1.484
8080
3127
1.516
3206
3304
1.579
3557
3658
1.638
3000
4004
-8
h
it
3
524
.572
566
.591
758
.646
822
.676
012
.714
968
.736
1034
.762
1112
.790
1201
.822
1332
.866
1638
.926
1666
.936
1750
.966
1834
.980
1017
1.000
2032
1.031
2212
1.073
2271
1.089
2473
1.136
2745
1.195
2m)
1.243
3218
1.289
3679
1.376
4474
1.485
4938
1.557
5161
1.591
5384
1.623
5820
1.687
7085
1.808
i
i
A
A
A
I
Insulation
Resistance in
Megohms
Mile.
S
6
700
700
700
700
000
600
600
600
600
550
550
550
550
550
550
550
500
500
500
500
450
450
460
400
400
350
350
350
350
.Sfi
1200
1200
1200
1200
1100
1100
1100
1100
1100
1000
1000
1000
1000
1000
1000
1000
900
900
000
900
800
800
800
700
700
600
600
600
600
(
Hon. — Add -fg' to single braid for diameter of double bfaid.
^or j^' insulation the insulation resistance will be in proportion with A'
■n^A' insulation.
"^^ pressure for A' Red Core, 10,000 toKs; White Core, 12,000 Tolts
PROPERTIB8 OP CONDUCTORS.
B CMaHMf T1
TiaT PBDviuBm. —
3000 Vol™ roil
30 M
MUTEB.
L^td.
Brmided.
lomila.
■ndC.M.
II
Mi
i
1
.s
740
M
iie2
.8
440
600
1728
9
WH)
653
SOO
1880
OM
7S8
BOO
2123
t
a 1
900
2358
077
1063
500
3847
3 1
230
13S2
600
100000
^
301
600
331T
3! 1
1633
500
125000
3631
t
41 1
X>ft
1800
GOO
40*S
1967
4333
51 1
600
000
4610
K 1
M7
2381
GOO
4968
71 1
tS6
3638
500
0000
6318
A
7; r
66V
2805
600
TutPfb.™
.,-8000 VOLT5 TOS 30 Mi»DT«.
I-d«..
Bniid«l.
Iiunila-
udCU.
i .
t
1
.9
S I
1
u
Sis-
I8S2 1
2144 1
IKH
133
796
2332 1
236
170
913
900
2400 I
292
Z36
1029
000
2B26 1
363
3354 1
463
J 1
Jt56
1378
900
451
1647
000
lOOOOO
3947 1
900
4134 1
MS
SMI
800
136000
4385 1
607
594
3083
800
00
4636 1
3361
800
leoooo
S372 1
77(1
800
000
6108 I
t 1
740
2606
800
3OOO0O
6500 1
831
2967
800
6SB3 2
036
J 1
S6E
3238
800
RUBBER INSULATED WIRES AND CABLES.
I^VT Pbusukb, — 16,000
LMdad.
Br>id«d.
'"i'Bf
wIC.U.
i
1!
pi
11
i
i.3:«
1300
3077
1.4M
362
1087
1300
3283
i.S38
440
1224
1300
3488
1-5M
i 1
toe
1353
1200
3707
1S36
1300
4046
1.723
J 1
626
ITSl
1300
1.818
721
2030
1100
lOOOOO
1.043
ZIM
1100
0
S78e
l.BM
115000
2.030
•m
2490
1100
00
1
300
2670
uoo
ISOOOO
6677
! i
itoo
000
7013
2.170
MOOOO
i '
101
3421
1100
0000
7S23
2.205
i 2
I3J>
3707
1100
T
BTP.IB.
™«--26
000 VoLn roM 30 HiHim
I«ded.
iti,
Ill
1!
1.873
1668
1600
4437
I.OflO
1770
4661
3.008
HI1
1019
4885
3.064
1500
0710
2281
6535
3.256
im
2405
6005
3.351
IIW
1500
lOOOOO
7259
2.414
246
2908
7533
2.436
271
3145
1400
13W00
7838
3.500
33S
3354
oo
3.530
3563
1400
uoooo
8400
2.576
3813
8SU
3.641
481
attwo
0302
1300
0000
0738
3.786
au«
4893
1300
172
PROPERTIES OF CONDUCTORS.
«eB«na fltoctefte GoaipaMy Bxtim ftoxil^le
Hub is adapted for use as brush-holder leads, or to any use
flexibility is required. The finish is Uaek glased linen braid,
of the strand is No. 25 B. & 8.
Eaoh wire
I
Dimensions in Inches.
' Number
arcular
liils.
Wires in
Strand.
Diameter
Thiekness
Diameter
Bare.
Rubber.
OirerAIL
25
8.000
.108
.047
.276
50
16.000
.150
.047
.820
76
24.000
.205
.047
.876*
100
32,000
.235
.047
.460
150
48.000
.285
.047
.600
200
64,000
.325
.047
.640
250
80.000
.350
.047
.600
300
96,000
.385
.065
.666
350
112.000
.425
.065
.706
400
128.000
.460
.065
.740
450
144.000
.485
.065
.765
500
160.000
.570
.065
.810
550
176.000
.530
.065
.830
000
192.000
.570
.065
.870
050
208,000
.605
.065
.935
700
224.000
.625
.065
.966
750
240,000
.640
.065
.970
800
256.000
.680
.065
1.010
900
288.000
.700
.065
1.030
1000
320.000
.725
.065
1.066
1250
400.000
.825
.065
1.166
1500
480.000
.880
.065
1.213
1750
500.000
.960
.093
1.360
2000
640.000
1.060
.093
1.410
2250
720,000
1.100
.093
1.500
2500
800.000
1.200
.093
1.600
2750
880.000
1.250
.093
1.650
3125
1.000.000
1.480
.093
1.830
^
SPECIAL CABLES.
173
GENERAL ELECTRIC COMPANY.
iblaa are adapted for use as brush-holder and field leads, and for
wiring ear bodies and oonneeting them to the trucks.
The jumper cable is made with an outside rubber jacket protected by tiro
braids, the outer being of the best linen thread. It is made very flexible for
eoaneeting cars, and is designed to withstand the constant swinging with a
auBiBunn Mwou«t of
f^A J
li
1^
•
8
4
is
A
Single Braid.
Extra Braided.
strand.
1
Nanbcr of wires and sise
of wireB.ft 8.
|5
Weight in
lbs. per
1000 ft.
Diameter
in
inches.
Weight in
lbs. per
1000ft.
1 j
Q -3
40/24
.180
107
.315
146
.600
49/^
.207
6
^
161
.362
200
.600
49/22
.226
4
174
.380
260
.626
49/21
.262
3
A
205
.407
281
.626
75/25
.206
6
A
132
.360
186
.600
100/25
.236
5
A
• • •
.390
286
.625
150/26
.285
4
260
.440
300
.625
200/25
.326
2
A
• • •
.480
446
.760
250/26
.350
1
A
.506
480
.750
860/25
.426
1/0
A
■ • •
.670
555
.750
7/.0485
.146
8
A
103
.280
146
.405
7/.0613
.184
6
^
138
.339
189
.464
7/.0773
.232
4
A
209
.387
276
.512
Type U Train Control
Siocle 19/26 ....
.090
12
A
• • •
• • • •
65.6
.280
9 GmifaKtor Tram Cable
.000
12
A
« • ■
« • • ■
600
.940
9 Gonduotor Jumper
CsbJe
.000
12
A
■ • •
• • « •
640
1.030
(
- Sade conduoton of both train and jumper cables composed of 19/26
B.CB. wires.
174
PROPERTIES OP CONDUCTORS,
UTAVY 0XA9|]»AJB1» ^tmjrsa.
In the following table are given uaes of Navy Standard Wires
■pedfications issued by the Navy Department in March, 1897.
•
8'2
e
Diameter
Diameter in
32d8
fe -
•
god
8«
m
Inches.
of
an inch.
<
Over
copper.
Over
Para
rubber.
Over
vulc.
rubber.
Ova-
tape.
Over
braid.
4,107
1
14
.06408
.0953
7
9
11
56.9
9.016
7
19
.10767
.1389
10
12
14
103
11.368
7
18
.12090
.1522
10
12
14
108.5
14,336
7
17
. 13578
.1670
10
12
14
115.5
18.081
7
16
.15225
.1837
11
13
15
140
22.799
7
15
.17121
.2025
12
14
16
165i
30.856
19
18
.20150
.2328
12
14
16
184
38.912
19
17
.22630
.2576
13
15
17
218
49.077
19
16
.25410
.2854
14
16
18
260i
60.088
37
18
.28210
.3134
15
17
19
314
75,776
37
17
.31682
.3481
16
18
20
371
99,064
61
18
.36270
.3940
18
20
22
463
124,928
61
17
.40734
.4386
19
21
23
557
157.563
61
16
.45738
.4885
20
22
24
647
198,677
61
15
.51363
.5449
22
24
26
794
250,527
61
14
.57672
.6080
24
26
28
970
296.387
91
15
.62777
.6590
26
28
30
1.138
373,737
91
14
.70488
.7361
29
31
33
1.420
413.639
127
15
.74191
.7732
30
32
34
1.553
Double Gonducto
r. Plain
, 2-7-22 I
J. & S. .
• • ■
• • •
• » •
181.5
Double Gonducto
r, SOk,
2-7-25 B.
AS.. .
• • ■
• ■ •
• • •
28
Double Gonducto
r, DiviE
ig Lamp, .
2-7-20 B
(.AS.
• « ft
• • •
218.3
Bell Cord, 1-16 E
;. Sc8.
20 7
PAPKII nSlTIiAarEO AITD I<KA]»K]» wxrbs aitd
CABMJEII.
GENERAL ELECTRIC 00.
There will be found on the following pages data of a full line of paper
insulated and lead covered wires and cables. All cables insulated with
fibrous covering depend for their successful operation and maintenance
upon the exclusion of moisture by the lead sheath; and this fact should
be borne in mind constantly in handling this class of cables, consequently
the lead on them is extra heavy. The use of jute and asphalt covering
over the lead is strongly recommended on all this class of cables, inasmuch
as their life is absolutely dependent upon that of the lead. Paper insulated
cables cannot be furnished without the lead covering.
PAP£B INSUI<ATED WIRES AND CABLES.
175
I. Solid.
B. 4 a and
CM.
10
8
6
5
4
A' Iiunil*tion
Test Pressure, 4000
Volta for 30 Minuiee.
^9 *
^8
413
461
530
674
626
-414
.441
.474
.494
.517
^1
A' Xxwulation
Test Pressure, 6000
Volts for 30 liinutes.
^8
493
542
613
660
716
.477
.603
.637
.667
.679
A
A
A
300
300
300
300
300
II. Stranded.
6
668
.WD
A
646
.669
A
250
6
606
.518
A
604
.681
A
260
4
662
.644
A
764
.607
s
250
2
814
.604
A
1.068
.098
250
1
1.072
.679
A
1.184
.742
A
250
lOOOOO
1,176
.708
A
1,289
.771
A
250
0
1,190
.718
A
1.316
.781
A
260
125000
1.276
.748
A
1,393
.811
A
200
00
1.364
.762
A
1.470
.826
A
200
160000
1,431
.782
A
1.647
.845
A
200
000
1.536
.813
A
1,656
.876
A
200
200000
1.703
.866
A
2,046
.949
A
160
0000
1.768
.871
A
2,106
.965
A
150
250000
2,165
.950
A
2,304
1.012
A
160
aooooo
2.435
1.009
A
2,574
1.071
A
160
aaoooo
2.660
1.067
A
2,804
1.119
A
125
4000OO
2,890
1.108
A
3.041
1.165
A
125
500000
3,029
1.252
i
4.106
1.315
i
125
600000
4,409
1.330
i
4.608
1.393
i
125
7U000O
4.876
1.402
i
6,067
1.466
i
100
750000
6.106
1.436
i
6.298
1.499
i
100
800000
6.337
1.468
6.623
1.631
i
100
900000
6.782
1.581
i
6.976
1.694
i
100
lOOOOOO
6,213
1.690
■J-
6,416
1.663
i
100
1250000
7.293
1.727
1
7.600
1.790
i
100
1500000
8.329
1.840
i
8.542
1.912
i
76
2000000
10.866
2.060
It
10.686
2.132
*
50
PS0PERTIE8 or GONDDCTOK8.
rmmmr
I cAi«.
1 ,.
Bp\^
4
^
h
n
?i
l^
s
U
i
U
n
S.9
|3
-9 ^
10
678
.030
iV
etw
.603
A
40O
s
632
.S«5
iV
87fi
.6S9
A
*00
e
707
.S09
iV
960
.693
A
6
t
1,011
g
40O
*
003
,673
1,078
.738
400
i
egg
716
400
943
674
1,056
737
1
400
i,oia
700
1,1S4
400
1,800
833
360
1,300
804
1.420
867
360
1.407
S33
1,639
896
1,433
1,566
906
360
1.618
878
1.762
967
j
360
1.693
887
1,049
981
300
1,802
001
300
2006
970
3,147 1
033
300
a,lB7 1
01!
3,330 1
A
2,246 I
3,390 1
090
^
250
3.451 1
076
Z897 1
137
a.734 1
134
269
a,9B8 1
3,716 1
307
8.796 I
290
3,980 1
363
4.29f) 1
377
440
4.793 1
i&6
4,983 1
5,209 I
E27
I
5,463 1
890
5.600 1
624
6.721 1
639
666
«.189 1
666
j
6,390 I
719
e.63i 1
716
6,838 1
778
j
7,943 1
8.776 I
9,001 3
10,834 2
IM
i
11,066 2
367
PAPER INSULATES VHtES AND CABLES.
D«w»a cSSmi.
T«t Prwin. ie,60O
i
C.H.
k
Bi
l=-
IM
"5 =
1.IB7
.S20
t
1,770
1.030
eoQ
1.223
fm
1,S46
i.oeg
SCO
1.313
fWl
1,0«
LOW
BOO
1,309
mt
3.013
i.iie
5G0
1.868
953
iV
%080
1.141
eeo
<
n. BtrudMl.
1.357
003
■ '
3.001 1
121
600
1.63B
OSS
2,008 1
143
600
600
l'.917 1
0*1
■ ■
2.e6S 1
2B2
600
aJ3B2 1
OSS
330
Mnooo
2,17B 1
3,207 1
4S0
0
3.204 1
3.800 1
376
460
usooo
!l.aB3 1
164
3.404 1
406
4S0
00
3.3S2 1
168
3.608 1
lEOOOO
3.063 1
3.610 I
430
480
3,2ie 1
383
3,766 1
470
460
noooo
8.400 1
8.970 1
40O
oooo
3.473 1
340
4.046 1
3S000O
3.70« 1
387
4.203 1
676
400
4sm 1
440
4.811 1
034
400
asoooo
a.393 1
4«
4.8S8 1
360
«»0OO
4,6» 1
640
6,108 1
738
360
wnoo
6,088 1
037
6,707 1
816
300
«aoooo
SM* 1
708
j
0,328 1
803
soo
TDOOOO
8,087 1
777
0.740 1
see
300
noooo
8.331 1
Sll
e.as3 1
BOB
300
0,666 1
7.334 3
031
800
mooo
7.040 1
SOS
7.708 2
UOOQOO
SOS
8.171 3
163
aso
13S0OOO
8.808 3
9,334 2
290
200
UOQOOO
B.703 3
mnooo
11.810 2
443
I
12,670 a
031
160
PROPERTIES OP CONDUCJrORS.
TbtP
nacRB. 3000 Vo
LTBTO
^
Tmt Pucuhrb. SOOO Voub
30 AiNDTM.
FOB 30 MiNims
B. « S. and
1
ll
■^i
%i
1
i
J^
]
C. U.
1^
ji
i
i
s
ii
8
138S
150
■cot
30O
18T4
ITS
12S
182
175
2270
l!o83
125
218
175
2
2837
346
IM
1,314
j
ISO
3035
1.437
100
504
150
0
3SM
160
125000
1.634
ISO
4420
1.653
100
823
12S
150000
4750
063
126
000
I2S
6300
1.815
i
100
879
135
0000
0700
j_
r»
\_±
filtt
125
■Tan P
■ButntE, 15.000
VOLTB
nPtaa
yiiSSS"--
ran 30 Hindt»
~A~~
319B
A
300
742 2
100
6
3422
A
275
020 2
150
400
4
3646
299 3
208
400
2
278
052 S
835
400
4708
1.837
275
581 2
433
S50
100000
I.S63
883 3
495
360
275
618
850
I2S000
6433
2.040
275
493 2
580
360
00
6766
841 2
908
350
250
246 2
350
000
7513
2.190
250
057 2
730
200000
7»80
2.208
160 2
806
3O0
0000
S44fl
2,315
250
983 2
845
300
Thlakne»o[ mndotio
nfn
r3000 V
?s
S-:
"*
15 000
itor. A' I»P« oym
for
38.000 V
CAUBRIC INSULATED WIBES AND CABLES.
WoaEiHo PanaoBE, t.OOO Vova ok Low.
TsBT PbBBcsb, 3,000 Vovn.
Braided.
Laded.
W^hl in
Weight ia
^r^K^ (t.
1000 ft.
I>iq>lci «bl« Imr^t* thw 2SO.00O Cm. »n diffisult to hwdlfl and thers-
■n» fourth colunui — Dik. in Inches — is the over-mil dinineter of the
Uriwd oiljli and la iv>pn>xlni»tal}' tbs mas for (itber btaided or leaded.
PSOPBBTIBS OF CONDUCTOB8.
WoBKora PuaanxB, S.OOO Voun o* Ln*.
Thiok.
LwliD
Brudsd.
Wsichtin
1000 ft.
400.000
eoo.000
TSO.OOO
1.000,000
1.260,000
1. 100,000
2,000.000
2;673
3,14S
3,817
4.7M
S.TBS
Duplax ublaa largai than 290,000 Cm.
therefon are not noomnModed .
Ill* fourth oolumn — Dia. in tushea — is (he c
diffioult to bi
ov«r-all diuuv
biaidodoi
CAMBRIC INSULATED WIRES AND CABLES.
a PsMaimB, 5,000 Voun om L
■T Pbhsumb, la^SOO VoLia.
TWet Tbiek.
Inohn. Iiuhn.
BraidMt.
Dik. ID Wnght in
Lidn Lba.
2100
2347
2Gfi«
-fl difficult to handle and tbere-
— M«. in Ineh«« —
r
182
PROPERTIES OF CONDUCTORS.
ITandAlMd
Working Pressttrk, 7,000 Volts ob Lbss.
TsBT PsESSURB, 17.500 Voivre.
)
Size.
B. A S. and C. M.
Thick,
Ins. in
Inches.
Thick.
Lead in
Inches.
I>ia.in
Inches.
Braided.
Weight in
Lbs. per
1000 ft.
Leadarl.
Weight in
Lbfl. pa*
lOOO ft.
6 Sol.
A
A
.68
320
851
4 Sol.
A
A
.72
380
058
est.
A
A
.70
336
884
4 St.
A
A
.76
413
1002
2 St.
A
A
.81
620
1164
ISt.
A
A
.88
605
1505
1/0 St.
A
A
.05
730
1871
2/0 St.
A
A
1.00
860
2047
3/0 St.
A
A
1.05
1003
2254
4/0 St.
A
A
1.11
1175
2506
250.000
A
1.15
1317
2718
300,000
H
A
1.24
1565
3003
400.000
a
A
1.36
1064
3627
500.000
A
1.46
2364
4161
760,000
4s
n
1.67
3264
5707
1,000.000
A
i
1.85
4155
7279
Daplex cables larger than 250.000 Cm. are difficult to handle and there-
fore are not recommended.
The fourth column — Dia. in Inches — is the over-all diameter of the
finished cable and is approximately the same for either braided or leaded.
1
CAMBRIC INSULATED WIRES AND CABLES.
183
WoKKiNQ PRsasimx, 10,000 Volts ob Lbm.
P&BMmiB, 25,000 Voun.
Siae.
B. k S. and
CM.
Thick.
Ins. in
Inehes.
Thick.
Lead in
Inches.
Bia. in
Inches.
Braided.
Weight in
Lbs. per
1000 ft.
Leaded.
Weight in
Lbs. per
1000 ft.
6 Sol.
i
A
.80
424
1063
4 Sol.
A
.84
408
1176
est.
■ ■
A
.82
441
1102
4 St.
• ■
•h
.87
521
1227
2 St.
y
A
.00
712
1651
ISt.
A
1.04
703
1925
1/0 St.
A
1.08
801
2182
2/0 St.
A
1.12
1009
2365
3/0 St.
A
1.17
1150
2580
4/0 St.
A
1.23
1327
2839
250.000
A
1.28
1483
3058
300.000
A
1.88
1707
3353
400.000
1.48
2087
4031
£00.000
X
1.57
2467
4709
750.000
1
n
1.80
3458
6470
1.000.000
i
1.96
4386
7688
(
Dovlex caUea laxser than 250.000 Cm. are difficult to handle and there-
fare are not reoomxnended.
TIm foorth oohimn — Dia. in Inohee — is the over-ail diameter of the
bnfaed cable And ia approziiiiately the same for either braided or leaded.
184
PROFEBTIES OF CONDUCTORS.
W«
WOBKDrO
Tmn
)
listed CtaiftlM.— Ma«le
K, 16,000 VoLom OK
PftaBSmus, 83.000 Voxab.
SiM.
B. &. 8. and
Thick.
Idb. in
Thick.
Lead in
DUkin
Braided.
Weight in
Leaded.
Weight in
CM.
Inch«8.
Inches.
Inches.
Lbs. per
1000 ft.
Lbe. per
1000 ft.
6 Sol.
u
A
1.06
660
1039
4 Sol.
•: •
A
1.10
767
2084
est.
■1 •
1.08
705
1994
4 St.
•1 '
A
1.12
797
2163
2 St.
A
1.18
927
2373
ISt.
•
■
A
1.29
1110
2098
1/0 St.
■
•
A
1.83
1225
2860
2/0 St.
,
•
A
1.87
1360
3061
3/0 St.
■
•
A
1.42
1538
3288
4/0 St.
1
•
A
1.48
1732
3562
250,000
.
■
i
1.63
1901
3795
300.000
■
1.63
2130
4487
400.000
f
1.73
2530
6246
500.000
1
I
1.82
2930
6006
750.000
tt
4
2.05
3998
7468
1,000.000
*
2.23
6006
8d36
Duplex cables larger than 260,000 Cm. are difficult to handle and there-
fore are not recommended.
The fourth column — Dia. in Inches ~- is the over-all diameter of the
finished cable and is ^;»prozimateiy the same for either braided or leaded.
CAHBBIC IN8TTLATBD WIRBe AND CABLES.
WdkUHa PmiiaiFmB, 1.000 Voun oa I w.
1. 3.000 Voum.
Six.
B. A&ud
aM.
TUcsk. Ins.
inlnch».
TTiiA-
Inclua.
ll-.I»r
Laded.
WBishtiD
LbM»
'■"^
1000 ft.
1000 ft.
;
U
J
.87
z
1034
1
1.17
1340
2437
I/O
J 1^
g
1.34
1480
1781
31S2
i J
Jj
l.«
1.58
3144
30S9
4536
4/D
* i
S331
190.000
i
1,97
3784
7107
WoaEDia Pkihdu. 3.000 Voiob oa
TiBT .PanaiiBB. 7i>00 VoLie.
s^
A 1
fW
804
1837
1029
2170
1 i
27
1384
3679
3343
«)
1W4
38S3
3/0
1 A
BO
2354}
3/0
7R
2S31
B172
4/0
i
3504
flS24
1»M»
i A
07
3083
7498
9 Gnt eoluom is the
:h eoBdoctor'aiid the second eotumn !■ the thici
iltiiiui — DU. In Inohaa — in the over-all dia
186
PROPERTIES OF CONDUCTORS.
Working PasasuBB, 5,000 Vouis cm Lbm.
Tbbt Pbbbsubs. 12,600 Volts.
)
Sise.
B. A S. and
Thick. Ins.
in Inches.
Thick.
Lead in
Inches.
Dia.in
Inches.
Braided.
Weight in
Lbs. per
Leaded.
Weight in
Lbs. per
1000 ft.
1000 ft.
6
A-A
A
1.20
956
2419
4
A-A
A
1.30
1204
2804
2
A-A
A
1.43
1601
S361
1
A-A
A
1.56
1916
8834
I/O
A-A
A
1.64
2221
4268
2/0
A-A
A
1.74
2608
4792
3/0
A-A
i
1.91
3083
6287
4/0
A-A
i
2.03
3650
7090
250.000
A-A
i
2.13
4118
7755
WORKINa PBBBStTRB, 7,000 VOLTB OR Ll
Tbbt Pbbbsure, 17,500 Voum.
6
4
2
1/0
2/0
3/0
4/0
250.000
»-4
A
1.42
1304
3056
i-i
A
1.53
1583
8473
i-i
A
1.66
1979
4057
i-i
i
1.81
2268
5296
i-i
i
1.89
2602
5783
i
1.99
3001
6364
i
2.10
3597
7169
i-i
i
2.23
4077
7890
i-i
i
2.33
4610
8697
Under "Thickneaa of Insulation '* the first column is the thickness of
insulation on each conductor and the second coKunn is the thickness over all.
The fourth column — Dia. in Inches — is the over-all diameter of the
finished cable and is ^proximately the same for either tvaided or leaded.
CAMBBIC INSULATED WIRBS AND CABLES
* -"ti— *— - I— l««aJ CMilM. — Triple 0*i
WoaKiHa Phbwuib, 10,000 Vomb <■■ L^h.
Tut pBaauKE, 25,000 Volt*.
Bnidad
B.A&HK1
Thiek. Ids.
in Inchs.
iDcfaa. '"
ha.
Weight in
Lb». pet
1000 ft.
Wrighl in
Lb..P«
1000 It.
i
1 1
ez
73
so
1833
1030
38S1
4713
3860
0433
10
3222
6M3
a/0
2B
3000
J/0
40
11BS
8343
1
S2
4851
eisa
tsoooo
i
j-a
oa
5405
0933
WoKKJHa PaXHDBE. 16,000 VoLTfl
Ttot PaEHDBi, 33,000 Vol
1^ A
1
82
3005
4.2S9
ll .
4.744
1
30
2768
3320
9,305
7,2H
1/0
39
3715
7303
2/0
8.485
S»
4731
a.aoi
4/0
72
6406
^
82
6B82
10,851
Undw "Hucknw ot ImnilatioD" the fint column is (he Ibkkqen of
innliboa OQ each conduetor »nd the seconJ coluEon ia the thickoesa over all.
The foonh oolumn — Di*. in Inches — is tho overall dinmeter of the
faiiihcd cable and is approionuitely Che name for either bruded or leaded.
188
PROPERTIES OF CONDUCTORS.
BUtmrnHMmA for llMtoiyr^i
w JLmtUa Um.
I
The ioBulation of these oablee is dry pi^Mr. The foUowiog qMoifioatioiie
have been adopted by the larcer telephone oompaniee wid» therefore, loay
be considered standard*
€;al>le Coadvct^r. No. 10 B. and S. G.. 08% oonduotivity. inrnilatfij
with one or two plater tapes; conductor twisted in pairs; one of the pain
to have a distinctive colored paper for marker; len^^th of twist not to exceed
3'. Pairs to be laid up in reverse layers; insulation to be unsaturated ex-
cept two feet from each end to prevent moisture from entering. The lead
sheath to have an alloy of 2^ to 3\% of tin; thickness of sheath A* for
fifty pair of cables, /b* for one hundred pair of cables, and ^' for iaiKsr
sixes. Insulation resistance to be at least 100 mecohms per mile after Uie
cable is laid and spliced. Electrostatic capacity no greater than .054 with
a maximum of .060 microfarads per mile.
The aeHal cables for telephone companies usually follow the same speci-
fications as those for underground use, being purchased with the ultimate
intention of being put underground. Gables that are to remain overhead
indefinit^y are usually made with a lighter sheathing of lead than tlwt
specified for underground work.
Number Pairs.
Outmde Diameters.
Inches.
Weights 1000 feet.
Pounds.
1
^
214
2
#
302
3
*
515
4
A
620
5
t
747
6
H
877
7
■ i
012
10
' i
1.214
1,375
12
i V
15
1
1.566
18
IJ^
1.758
20
l4
1.040
25
iX
2.332
30
l£
2.748
35
1»
2.085
40
^f'
3,176
45
11
3.365
60
3.678
55
11
3.867
«0
If
4.055
65
IH
4.241
70
2
4,430
80
2|
4,804
00
2<
5.180
100
«
5,505
SUBMARINE CABLES.
189
for V:
C»r
▲erial Vae.
The xnautaifcion of these cables is made of a compound containing not
hm than thirty per cent pure Para rubber. These specifications may be
oooaidered standard, being used by the principal telegraph companies.
¥»SMlMtf»J Aerial Vel«gT«ipli Cable.
GngeB.ft8.
No. of Conductors.
Outside Diameter.
Weight per 1,000 ft.
14
14
14
7
10
19
li^
426 lbs.
600 lbs.
8^ lbs.
i
GoDduetors No. 14 B. and S. insulated to diameter of 6-32', cabled
toieUier and covered with a rubber tape, one layer of tarred jute, a rubber
tspe, sad a heavy cotton braid saturated with waterproof compound.
•mBHAJtXlVS CAJBI.KA.
Hmss faf4<Mi are insulated with a rubber compound containing not less
tfasa thirty per cent (30%) of pure Para rubber.
Tbese specifications have been adopted by the various telegraph com-
psnia and the United States Government for general use.
No. of
Coadae-
(OCB.
Gauge of Con-
ductors.
No. of
Armor
Wires.
Gauge of Armor
iVires.
Outside
Diameter.
Weight
per 1.000
feet.
I
2
3
4
5
•
7
10
14 B. ft a
14 B. ft 8.
14 B. ft 8.
14 B. ft 8.
14 B. ft 8.
14 B. ft &
14 B. ft &
14 B. ft 8.
12
10
14
16
19
21
21
22
8 B. W. G.
8 B. W. G.
6 B. W. G.
6 B. W. G.
6 B. W. G.
6 B. W. G.
6 B. W. G.
4 B. W. G.
i'
1150
1675
2400
2760
8100
3600
8600
4600
GoBdaetors built up of 7 No. 21 B. ft S. copper wires, heavily tinned. Each
wadaetor Insulated with A" Rubber and Taped.
ne above specifications refer only to river and harbor cables. Ocean
Okies are of an entirely different character, and consist of Shore End, In-
Wnaediate and Deep 8ea Types.
PHOPEBTIES OP CONDUCTORa.
■ KbMmv Wmamlmtm* ObMm.
Upe, uid bare ilie t
a ths metdl oarrfully by m
or w)iD Bumpeper.
Mmtml JtoUit.— If solid oonductor, louf lb* ends with ■ file » u ta
give k good iont eoniact mrfacB (or Boldering, K oonduciot ia sInuidHL
carefully apnad apart the itianda, outting out lh» cmun » cooduotom
can be butted (ocethar, the louee ends inUrlaaitic an in Pig. 1, and bind
•rirei down tight as in Fig. 2. witb gn or other plien. Solder wefully.
uniw no acid; resin ia the b«t, althotiifa jc
candle as beins handy to UM and eaey to pro*
Aoldeied by dipi^ag Che joint into a pot of mi
molten metal over tt
be insulated aa previously dooribed.
r ebo* a atyle of oo
lolder; when dry a
JOINTS IN CABLES. 191
_^ tMe ^•Ibc— Jointers must have absolutely dry and
E hands, and all tools most be kept in the best possible condition of
[ness. Clean the Joint carefully of all flux and solder ; scarf bacli: the
r insulation like a lead-pencil for an inch or more with a sharp knife.
Ohiefully wind the joint with three layers of pure unvulcanised rubber,
~ 1^ care not to touch the strip with the hands any more than neces-
; orer this wind red rubber strip ready for yulcanizing. Lap the tape
k tlw taper ends of the insulation, and make the coyerms of the same
r as the rubber insulation on the conductor, winding even and
OoTcr the rubber strip with two or three layers of rubbw-saturated
^Tertrnf. — If the insulation is covered and protected by lead, a
kxise sleeve is slipped over one end before jointing, and slipped back over
the joint when tne insulation is finished, a plumber's wiped joint being
■ade St the ends.
Fio. 9.
VelHta l» Wavlnir Cable*.— This cable Is covered with cotton,
tkoronghly impregnated with a composition of hydro-carbon oils applied at
U|b temperature, the whole beina covered with lead to protect the iusula-
tioo. Thelnsnlating properties of this covering are very high if the lead is
knt intact.
Metai joints are made as usual, and a textile tape may be used for cover-
iag the bare copper. A large lead-sleeve is then drawn over the joint,
and viped onto the lead covering at either end : then the Interior space is
filled with a compound similar to that with which the Insulation is im-
pregnated.
. ^per t— latid Cablea. — This cable is covered or
luslated with narrow strips of thin manila paper wound on spirally, after
vh&eh the whole is put into an oven and thoroughly dried, then plunsed
late a hot bath of resin oil, which thoroughly impregnates the paper. This
iasoktion is not the highest in measurement, but the electrostatic capacity
b lev Bud the breakdown properties high. When used for telephone pur-
C«s Uie piqper is left dry, and is wound on the conductor very loosely, thus
▼ing Ivge air spaces and giving very low electrostatic capacity.
Joints are made as in the waring cable by covering the conductor with
paper tape of the same kind as the insulation, then pulling over the lead
■leere, which is finally filled with parafflne wax.
^ — A new joint for stranded or solid conductors is made
by Doswirt Sc Company, of 59 Fulton Street, New York. It is said to have
a BMcfaaaical strength exceeding 75% of that of the cable itself, and an
eleetriesl conductance in excess of that of the cable.
The joint for stranded conductors consists of (see Fig. 10) a compressor
ant **&," an outside ring "b,'' an inside ring *'c,'^ and a nipple "d.'^ The
iBStthree parts are in duplicate.
Jm joint is applied as shown progressively in Fig. 10. The wire is first
■v^ppedfor a space A of an inch longer than the compression nut. The
MBqwenon nut and the outside ring are then slipped on, being driven
>^M with a steel driver provided for the purpose. The outer strands are
tftt separated and the inner ring slipped on over the central core and
skD dnyea home with a special driver. The outside strands are then
|)Boulded back into ix>sition and the nipple is screwed in place still further
m fonniBg the joint into shi4>e.
I
PROPEBTIEIS OF a
mftcr the luhliL.
By unettinc
tba ■phViilov*,
Fro. 12. AHsinbly.
(ubttuitial hooli, oanfulty nukchinad ta
of the ioint. The ahuk of the hook ii
nlptils of the Randiird DgaMri joint for
feuLlAbJy nbmped CASting. wtuch fit* in the epuia bi
hue of the hnok, ii held in pliuie hf mevu of ■ nom
JOINTS IN COPPER WIRES.
193
jr^latlair C(«tte-P«v«ha Covered frir««
the gutta-peroha for about two inehcs from the ends of the
whieh are to be jointed. Fif. 14.
Fio. 14.
If«ct mes tiie wires midway from the gutta-pereha, and grasp with the
fig. 15.
Fio. 15.
Thea twist the wires, the overiapping right-hand wire first, and then,
letvetsiug the grip of the pliers, twist the left-hand wire over the right. Cut
^ the BuperanoQaendflof the wires and solder the twist, leaving it as shown
in Fig. 16.
(
Fio. 16.
Next warm up the gutta-percha for about two inches on eadi side of the
twist. Then, first draw down the insulation from one side, half way over
Fio. 17.
the twisted wins. Fig. 17. and then from the other side in the same way. Fig.
1&
Fig. 18.
Then tool the raised end down evenly over the under half with a heated
{too. Then warm up the whole and work the "drawdown" with the thumb
md forefiiicer until it resembles Fig. 10. Now allow the joint to cool and set.
Fio. 10.
Next roagjien the drawdown with a knife, and place over it a thin eoating
of Ghatterton's compound for one inch, in the center of the drawdown,
which is also allowed to set.
Next cut a Uiick strip of gutta-percha, about an inch wide and six inches
194
PBOPERTIE8 OF CONDUCTORS.
long, and wrap thlB, after it has been well warmed by the lamp, evenly OTer
the center of the dvawdown. Fig. 90.
Flo. 20.
The strip is then worked in each direction by the thumb and forefinger
oyer the drawdown until it extends about 2 inches from oenter of draw-
down. Then tool over carefully where the new insulation Joins the old,
after which the ioint should be again wanned up and worked with the fore-
finger and thumb as before. Then wet and soap the hand, and smooth and
round out the joint as shown in Fig. 21.
Fio. 21.
Between, and at e.Tenr operation, the utmost care must be ezerolMd to
remove every particle of foreign matter, resin, etc.
NoTB. Cbatterton's compound consists of 1 part by weight Stockholm tar;
1 part resin; 8 parts Qutta-percha.
Pliyalcal Cmwtamta •f CoMincrctally (<»•%)
Per cent Conductivity (Copper 100)
&>ecifio Gravity
Founds in 1 cubic foot
Pounds in 1 cubic inch
Pounds per mile per droular mil
Ultimate strength.
sq. m.
Modulus of Elasticity, .-
lb. X in.
m. X aq. m.
Coeffident of Linear Expansion per ^C.
Coefficient of linear Eximnsion per ^ F
Melting Point in *»C
Melting Point in "^F
Specific Heat (watt-eeconds to heat lib. l** C.)
Thermal Conductivity (watts through cu. in. temperature grad-
ient,l*0.)
Renttance
Microhms of centimeter cube at 0^ C
Microhms of inch cube at 0* C
Oluns per mile>foot at 0^ C
Ohms per miMoot at 20^ C
Ohms per mile at 0** C
Ohms per mile at 20®C. . . .
Pounds per mile-ohm at 0^ C. .
Pounds per mile-ohm at 20^ C.
Temperature coefficient per " C.
Temperature coefficient per * F.
2.68
107
.0007
.00481
26.000
0,000.000
.0000281
.0000128
025
1157
402
36.5
2.571
1.012
15.47
16.70
81.700
(dr. mils
88.200
oir. mils
808
424
.004
.0022
1
ALUMINUM WIRE.
Ids
Ahnnmmn wire of 62% conductivity is the generally accepted standard.
Atnminum d 92% c(»duotivity. bought at 2.18 times the price of cop-
per per pound, will give the same length and conductivity for the same
r for Mq««l "Mj^mt^tM
Cost per
of Copper of 100
Pound
Cost per Pound
% Conductivity.
of Alurainnm of 62% Conductivity.
14 cents
28.8 cents
15
*■
82.0
•«
16
M
84.1
i«
17
• I
36.2
••
18
t*
38.4
••
19
■•
40.6
••
20
M
42.6
••
21
M
44.7
••
22
M
46.8
tt
23
M
40.0
••
24
M
51.1
•(
25
53.2
tfTitt<
m for
i of Tariova
CondnctlTfttj
Metal.
Conduc-
tivity.
Cross
Section.
Weight.
Breaking
Weight.'
Price
per lb.
Copper ....
100
100
100.0
100
100
54
180
54.0
85.1
185
M
55
176
53.0
83.5
180
•4
56
173
52.0
82.0
192
M
57
170
51.1
80.6
196
M
58
167
50.2
79.2
199
••
50
164
49.4
77.9
203
N
60
162
48.6
76.6
206
m
61
150
47.8
75.3
210
m
62
157
47.0
74.1
213
m
63
154
46.3
72.9
216
* Breaking weights (i)ound8 to break wire of equal conductivity) are cal-
culated on tne assumption of an ultimate strength of 55,000 pounds per
sqpiare inch for copper and 26,000 pounds per sqiuure inch for aluminum*
196
PROPERTIES OP CONDUCTORS.
XWble«r
ieakttmmm^m of Solid AlmMiai
CondnctiTitj.*
PiTTSBUBa Rkddction Oo.
Oooducimty 02 in., the Matthiessen Standard Scale. Pure
weighs 167.111 pounds per cubic foot.
¥
ResistanceB at 70** ]
F.
LogcP.
OoS
R
LoeiL
IS
Ohms per
1000 Feet.
Ohms
per Mile.
Feet
per Ohm.
Ohms per lb.
0000
.07904
.41730
12652.
.00040985
5.325516
V. 897847
000
.09966
.52623
10034.
.00065102
5.224808
,.998521
00
.12569
.66362
7956.
.0010364
5.124102
1.099301
0
.15849
.83684
6310.
.0016479
5.023394
T. 200002
1
.19982
1.0552
5005.
.0026194
4.922688
T.30063B
2
.25200
1.3305
3968.
.0041656
4.821980
X. 401401
8
.31778
1.6779
3147.
.0066250
4.721274
,.502127
4
.40067
2.1156
2496.
.010631
4.620666 ;. 602787
6
.50526
2.6679
1975.
.016749
4.519860 T.703515
6
.63720
3.3887
1569.
.026628
4.419152
X.804276
7
.80350
4.2425
1245.
.042335
4.318446
T. 004986
0.006662
8
1.0131
5.3498
987.0
.067318
4.217738
0
1.2773
6.7442
783.0
.10710
4.117030
0.106293
10
1.6111
8.5065
620.8
.17028
4.016324
0.207122
11
2.0312
10.723
492.4
.27061
3.915616
0.307763
12
2.5615
13.525
390.5
.43040
3.814910
0.408494
18
3.2300
17.055
309.6
.68437
3.714202
0.600203
14
4.0724
21.502
245.6
1.0877
3.613496
0.609860
15
5.1354
27.114
194.8
1.7308
3.513788
0.710574
16
6.4755
34.190
154.4
2.7505
3.412082
0.811373
17
8.1670
43.124
122.50
4.3746
3.311374
0.912063
18
10.800
54.388
97.15
6.9590
3.210668
1 .012837
19
12.985
68.564
77.06
11.070
3.109960
1.113442
20
16.381
86.500
61.03
17.596
3.009254
1.214340
21
20.649
109.02
48.44
27.971
2.908546
1.314899
22
26.025
137.42
38.4
44.450
2.807838
1.416301
23
32.830
173.35
30.45
70.700
2.707132
1.616271
24
41.400
218.60
24.16
112.43
2.606424
1.617000
25
52.200
275.61
19.16
178.78
2.505718
1.717671
26
65.856
347.70
15.19
284.36
2.405010
1.818595
27
83.010
438.32
12.05
452.62
2.304304
1.919130
28
104.67
552.64
9.55
718.95
2.203696
2.019822
29
132.00
697.01
7.58
1142.9
2.102890
2.120574
30
166.43
878.80
6.01
1817.2
2.002182
2.221232
31
209.85
1108.0
4.77
2888.0
1.901476
2.321909
32
264.68
1397.6
3.78
4595.5
1.800768
2.422721
33
333.68
1760.2
3.00
7302.0
1.700060
2.623330
34
420.87
2222.2
2.38
11627.
1.599364
2.624148
35
530.60
2801.8
1.88
18440.
1.498646
2.724767
36
669.00
3532.5
1.50
29352.
1.397940
2.825426
37
843.46
4453.0
1.19
46600.
1.297234
2.926064
38
1064.0
5618.0
.96
74240.
1.196626
3.026942
89
1341.2
7082.0
.75
118070.
1.095820
3.127494
40
1691.1
8930.0
.69
187700.
0.995112
3.228169
* Calculated on the basis of Dr. Matthiessen 's standard, vis.: The
sistance of a pure soft copper wire 1 meter long, having a weight of 1 enxa^
.141729 International Ohm at 0" C. The purest alununum obtainable has a
conductivity of over 63 per cent, but this gain in conductivity is at a greatly
increased cost.
STHANDED ALUMINUM WIRE.
■ded lT»a«fcei'pi'««f AlaatlBBii Wire.
(Triple Bimid.)
udB. AS.
^^sr
\^%
SsM w-sr
VSSb's:
231
wof
H. W. Bock.
Betelin CoDdactiTitr ■2%.
Rautance per Hil-f<w( lO.SS ohmt
TeccqMratare 76* F,
BmMic Limit 14.000 lbs. per sQiure in
Dtlimkta Strencth 20,000 Iba. per iquue in
I
M
it
n
a
a
MU
ly
li
I
!«
I
H
.-;
ill
ll Sasis sSisS SSiSi siiis
°» SKsSo 53*»3 SSSSa 2S_,2"'
.T -" , ,"""."1P ^''l^ , . **. . .*^''! T*^ , . .
IBON AND STEEL WIRB.
199
1. Struftded wire should alwavs be used, even in the smaller tises, as
tbe action of the wind causes solid aluminum wire to "crvstallise," thereby
its strangth; also, there is less liability of flaws in the metal
camuiff trmtrngTi
y» ^hr***!**""* gathers much less sleet than copper.
8u It ooots less to string aluminum than copper, due to the less weight.
4. Qve must be taken in stringing tflununum to prevent denting and
abrasion, as the wire is very soft.
5w Meefaanical and splice joints made without the use of solder are entirely
6L Wires should be strung far enough apart to prevent trouble from
barmng-off of the wire in case of a short eireuit.
7. ^le to its high ooeffiei«it of linear expansion and low tensile strength,
tba minimnm allowable sag for aluminum wire is considerably greater than
for copper. This is one great objection to aluminum for telephone and
telepapb Unea. For long spans the differenoe in deflection between alu-
nattiim and oopper wires may be so great as to require a considerably higher
pole in eaae aluminum is used, although the pole need not be as strong as
would be required for copper^ as the weight of aluminum for equal oon-
duetivity is but 47 per cent of the weight of oopper.
C^aatoata of ]B«at CfalTaalaed Telegmpli 'VTire.
Per eent Conductivity (copper 100)
Per eent Conductivity (pure iron 100)
teedfie Gravity
Ibunds in 1 cubic foot
n>andB in 1 cubic inch
Founds per mile per circular mil
Id*
Ultimate strength, -. —
sq. m.
Modulus of elasticity,: — ^ — ^-4—
m. X sq. in.
Coefficient of linear Ejcpansion per ° C
Coefficient of Linear Ebcpansion per * F
Point in • C
Point in **F
\& Heat (watt-seconds to heat 1 lb. 1** C.) .
Conductivity (watts through cu. in.,
temperature gradient 1* C.)
Mtencf
Maerohms per centimeter cube at 0" C. . . .
IBerohms per inch cube at 0^ C
Ohms per mil foot at'0° C
Ohms per mil foot at 20^ C
Ohms per mile at ** C
Ohms per mfle at 20^ C
Pounds per mi]eK>hm ^ C
Pounds per mile-ohm 20° C
Temperature (Toeffident per ** C
Temperature Coefficient per *^ F^
Iron.
16.8
05.5
7.8
487
.282
.014
66.000
26.000.000
.00012
.000067
1600
2910
200
1.39
9.5
3.74
67.2
62.9
302.000
dr. mils
832.000
cir. mils
4230
4700
.005
.0028
Steel.
12.2
09.2
7.86
480
.284
.0141
68.000
30.000.000
.00012
.000067
1475
2685
209
1.39
13.1
6.17
78.9
86.8
417,000
cir. mils
458.000
cir. mils
5850
6500
.005
.0028
200
PROPERTIES OP CONDUCTORS.
IKradile Ctal'
of ili« KUflieet Bl«ctric«l 4t«alUI
ROBBLING.
►
4
6
8
9
10
11
12
14
8
09
-0
•g
c
a
o .
in P
Mile
1
eight
per
M
730
.225
.192
540
.162
380
.148
820
.135
260
.120
214
.105
165
.080
96
I
mile,
mile,
mile,
mile,
mile.
Imile.
mile,
mile.
Approximate
Breaking Strain in
Poundo.
E.B.B.
B.B.
2.190
2.409
1.620
1.782
1.140
1.254
960
1.056
780
858
642
706
495
545
288 817
Steel.
2.701
1,998
1.406
1,184
962
792
611
355
Ayerage Reaistaaoe
in Ohma at 68'* F.
E.B.B.
B3.
6.44
7.53
8.70
10.19
12.87
14.47
14.69
17.19
18.08
21.15
21.96
25.70
28.48
33.33
48.96
57.29
Steel.
8.90
12.04
17.10
20.31
25.00
30.37
39.39
67.71
The values given in this table are averages of a larse number of tests.
They are withm the limits of the specifications of the Western Union Tele-
graph Company.
The average value of the mile-ohm is 4,700 for E. B. B. wire.
The average value of the mile-ohm is 5.500 for B. B. wire.
The average value of the mileK)hm is 6,500 for Steel wire.
The average breaking strain is 3 times the weight per mile for E.B.B.
wire.
The average breaking strain is 3.3 times the woght per mile for B. B. wire.
The average breaking strain is 3.7 times the weight per mUe for Steel wire.
The mile^m — weight per mile X resistance per mile.
Ctelrawlsed SigrBAl Stnuid. Sotmi fTirea.
Diameter.
Weight per 1000'.
EMmated
Breaking
Weight.
Inches.
Bare Strand.
Double Braid
W. P.
Triple Braid
W.P,
1-2
15-32
7-16
&-8
5-16
9-32
17-64
1-A
7-32
8-16
11-64
9-64
1-8
3-32
520
420
360
290
210
160
120
100
80
60
43
33
24
20
616
510
444
362
270
214
171
148
122
96
76
60
48
38
677
561
488
398
297
235
188
163
134
105
84
66
53
42
8.320
6.720
6.720
4.640
3.360
2.560
1.920
1.600
1.280
960
688
528
884
320
IBON AND STEEL WIRE.
201
• of Steel ITire.
ROBBLINO.
NoTB. — The breaking weights given for Heel win are not thoee of 5fael
Tdtgraph wire. Thev appl^ to wire with a tensile strength of 100,000
per square inch. This strength is higher than that oxtelegraph wire.
No..
Roeb-
iingO.
6-0
5^
4-0
3-0
^-0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
30
21
22
23
24
25
28
27
80
31
32
33
84
35
Diam-
eter in
.460
.430
.893
.362
.831
.307
.263
.244
.225
.207
.192
.177
.162
.148
.135
.120
.105
.092
.080
.072
.063
.064
.047
.041
.035
.032
.028
.025
.023
.020
.018
.017
.016
.015
.014
.0135
.013
.011
.010
.0095
.009
Area in
Square
Inches.
.166191
.145221
.121304
.102922
.086049
.074023
.062002
.054325
.046760
.039761
.033654
.028953
.024606
.020612
.017203
.014314
.011310
.008659
.006648
.005027
.004071
.003117
.002200
.001735
.001320
.000962
.000604
.000616
.000491
.000415
.000314
.000254
.000227
.000201
.000177
.000154
.000143
.000133
.000095
.000079
.000071
.000064
Breaking
Strain
100.000 lbs.
aq. inch.
16.619
14.522
12.130
10.292
8,605
7.402
6.200
5,433
4.676
3,976
8.365
2.895
2.461
2.061
1.720
1.431
1.131
866
665
503
407
312
229
174
132
96
80
62
49
42
31
25
23
20
18
15
14
13
9.5
7.9
7.1
6.4
Weight in Pounds.
Per
1.000 ft.
558.4
487.9
407.6
345.8
289.1
248.7
211.4
182.5
157.1
133.6
113.1
97.3
82.7
69.3
57.8
48.1
38.0
29.1
22.3
16.9
13 7
10.5
7.70
5.83
4.44
3.23
2.70
2.07
1.65
1.40
1.06
.855
.763
.676
.594
.617
.481
.446
.319
.264
.238
.214
Per Mile.
2.948
2.576
2.152
1.826
1.627
1.313
1.116
964
830
705
597
514
437
366
306
254
201
164
118
89.2
72.2
66.3
40.6
30.8
23.4
17.1
14.3
10.9
8.71
7.37
6.68
4.51
4.03
3.57
3.14
2.73
2.54
2.36
1.69
1.39
1.26
1.13
Feet in
2,000 lbs.
3.682
4.099
4.907
. 5.783
6.917
8.041
9.463
10.957
12.730
14.970
17,687
20.669
24.101
28.878
34.600
41.584
62,631
68.762
89.525
118,413
146.198
191.022
259.909
843.112
450.856
618.620
740.193
966,651
This table was calculated on a basis of 483.84 pounds per cubic foot for
ed wire. Iron wire is a tri6e lighter.
The breaking strains are calculated for 100.000 pounds per square inch
tbran^iout, simply for convenience, so that the breaking strains of wires
of aaj strength per square inch may be quickly determined by multiplying
the values given in the tables by the ratio between the strength per square
inch and Iw.OOO. Thus, a No. 16 wire, with a strenirth per square inch of
150.000 pounds, has a breaking strain of 407 X \^^ - ^10.6 pounds.
The "Roebling" or "Maricet wire Gauge" is now' used as standard for
ated wires in America.
202
PROPERTIES OP CONDUCTORS.
lUBSMATAlfCS W^JLIIEA.
SPKcmo Rbsistanck and Tempbratube CoBrFiciBirr.
Substance.
Platinum Bilver
(Pt 66. Am 33)
Patent-Niokel
(Cu74.41. Zn0.23.Ni26.10.Fe0.42.
Mn0.18)
Platinoid
(Cu 50 Zn 25.5, Ni 14, W 56)
German Silver
(Cu, Zn, Ni in various proportions)
MaDganin
(Cu, Ni, and Fe-Mn in varioiis propor-
tions)
Boker A Co.'s lala, hard
Boker & Co.'s lala, soft
Krupp's metal
Driver-Harris 0o.'8 "as."
Driver-Harris Co.'s "Advance" . . . .
Driver-Harris Co.'8*'Ferro-Nickel" . .
Constantin
Microhms
oer Cubic
(Centimeter
about
20*F.
31.726
34.2
32.5
10 to 46
42 to 74
50.2
47.1
85.18
55.8
48.8
28.3
50 to 52
Temperature Coeffi-
cient per ** 0.
.000248
.00019
.00025 to .00044
.000011 to .00014
—.000011
+.000005
.0007007
Small
Very small
.00207
««]
Silver.
German silver is an alloy of copper, nickel, and lino. The eleotrioal
properties of the alloy naturally vary considerably with the proportions of
the constituent metals. The proportion of nidcd present is ordinarily used
to distin^^uish the various alloys, as the amount of this metal jpreeent in the
alloy fixes the proportions of tne other constituents in order that the result-
ing material may be easily worked. As made in the United States, com-
mercial German silver is made with approximately the following propor-
tions.
(Dr. F. a. C. Perrine.)
Designation.
0>nstituents.
Resistance at ** C.
Per Cent.
Alloy.
Nickel.
Copper.
Zinc.
Microhms
Per Centi-
meter.
Ohms
Per Mil
Foot.
8
12.5
20
30
8
12.5
20
30
60
67
66
60
32
30.5
24
20
19
26
32
46
114
160
193
277
Specific gravity, 8.5.
Temperature toeffident per <» C, .00025 to .00044.
GERMAN SILVER WIRES.
203
•f «•
•Uvcr fl^ire.
1»%
a©%
81m.
B.dES.
Ohnuper
1.000 fW.
Ohms per
Pound.
0hmsj;>6r
1.000 Feet.
Ohms per
Pound.
No. 8
11.7
.235
17.6
.363
9
11.8
.374
17.7
.662
10
18.7
.696
28.0
•o94
11
23.5
.948
85.3
1.42
12
29.7
1.50
44.6
2.26
13
87.6
2.39
56.2
3.59
14
47.3
3.81
70.9
5.71
15
69.6
6.06
89.4
9.09
16
75.2
9.63
112.
14.4
17
94.8
15.3
142.
22.9
18
119.
24.3
179.
36.5
19
166.
40.9
232.
61.4
20
190.
61.6
285.
92.4
21
239.
97.9
359.
146.
22
302.
155.
453.
233.
23
381.
247.
671.
371.
24
480.
393.
721..
690.
26
606.
626.
900.
939.
26
764.
995.
114.
149.
27
964.
158.
144.
237.
28
121.
261.
182.
377.
20
153.
400.
229.
600.
30
193.
636.
289.
955.
31
243.
101.
366.
151.
32
307.
160.
461.
241.
88
387.
255
581.
383.
84
488.
407.
733.
610.
36
616.
647.
924.
970.
36
777.
102.
116.
154.
37
979.
163.
146.
245.
88
123.
257.
185.
386.
39
156.
409.
233.
614.
40
196.
652.
294.
978.
Db. F. a. C, Perrinb.
Perfaaiw the meet remarkable remstance alloy which has been produced
is manganin. invented by Edward Weston in 1889. It is composed of
co^cr, niekd, and ferro-manganese in varying proportions.
fTci. Nichols of Cornell, has shown that coils made of this material
sre spt to chance their resistance when successively heated to 100*^ Cent.
^ cooled toO**Cent.. but Dr. lindeck, working for the Reichsanstalt. states
that when a completed coil is aimealed at a temperature of 140^ Cent, for
vn boors, no finlher difficulty is experienced from any aging change,
*l^ha> produced by time or repeated heatings and coolings.
^A fortner advantage of man^^anin which has been noticea by Dr. Lindeck,
*wa used for resistance coils, is its very feeble thermo-electnc power when
y»q<PBd to copper, as is almost idways the case in standard coils. While
lor german sinner the thermo-electric power is between 20 and 30 micro-
voHa par degree Centigrade, and for oonstantin, an alloy of copper 50 parts
^^M^mekel 60 parts, having a temperature coefficient between .00003 and
•OCODl a thermo-electric power of 40 micro-volts per degree Centigrade is
"Old. the thermo-^eetrio power of manganin is not above one or two mioro-
^ws par degree.
(
204
PROPERTIES OP CONDUCTORS.
■lectrlcal P^pertt<
«• AMd COIUltltllMOM of IHtftBVABftM*
Dr. F. A. C. Perrxne.
1
Mi-
Composition.
Ohms
crohms
Temper-
ature Co-
efficient*
Authority.
per
Mil-
Cubic
Cu.
Fe. Mn.
Ni.
Foot.
Centi-
meter.
Nichols
78.28
14.07
7.65
• • •
0.000011
Nichols
51.52
31.27
16.22
• p •
• • • • •
0.000039
Perrine
70.
25.
5. ) J, 4)
392
65.15
Perrine
65.
30.
s-lli
404
67.2
Perrine
65.
30.
6.)S5
443
73.6
Feussner and Lindeck
73.
24.
3.
287
47.7
0.00003
Lindeck
84.
12.
4.
253
42.0
0.00014
Dewar and Fleming .
84.
12.
4.
287
47.64
0.0000
leitaiona, Realatttnco, and Weicltta of
BoKER A Co.'s IaIa.
RosUtanco 11^1
I
Specific gravity 8.4
Microhms per centimeter cube, 0^ C, hard 50.2
Microhms per centimeter cube, 0° C, soft 47 . 1
Microhms per mil-foot, 0^ C, hard 3.10
Microhms per mU-foot, 0° C, soft 28.4
Temperature co^&cient per 0° C, hard . — .000011
Temperature coefficient per 0° C, soft + .000005
Carrying
B. &. S.
Gauge
No.
Diameter,
Inch.
Area,
Circular,
Mils.
Ohms per
1000 Feet.
Feet per Lb.
Approxi-
mately.
Capacity
with Free
Radiation
Amperes.
14
.0641
4107.
73.5
86.
■ • • •
16
.0508
2583.
116.9
135.3
• ■ • ■
17
.0453
2048.
147.4
170.6
• • ■ •
18
.0403
1624.
185.9
215.5
15.8
19
.0359
1289.
234.3
271.0
13.6
20
.0320
1024.
295.6
842.3
11.5
21
.0285
812.3
374.4
433.
9.7
22
.0253
640.1
470.1
543.5
8.0
23
.0225
506.25
596.6
689.6
6.8
24
.0201
404.
747.6
870.
5.8
25
.0179
320.4
945.6
1098.
.4.9
26
.0169
252.8
1192.9
1370.
4.1
27
.0142
201.6
1497.8
1724.
3.6
28
.0126
158.8
1890.1
2174.
3.1
29
.0113
127.7
2407.8
2777.
2.9
30
.0100
100.
3005.3
3448.
2.7
31
.0089
79.2
3789.2
4347.
• • • ■
32
.0080
64.
4779.1
5555.
2.5
33
.0071
50.4
6025.1
7142.
■ • « •
34
.0063
39.69
7600.4
9090.
2.2
35
.0056
31.56
9582.7
11100.
• a • •
36
.005
25.
12081.
14286.
2.0
37
.0044
19.83
15229.
17543.
....
38
.004
16.
19213.
22220.
a . . .
39
.0035
12.25
24218.
27700.
....
40
.0031
9.61
30570.
35714.
• . . •
Supplied by Boker Co.. 101-103 Duane St., New York.
boker's resistance ribbon.
205
I» K« <^wai«7.
•
S4
Ohms per 1000 feet.
ni
o
iin.
1 in.
fin.
i in.
1 in.
|in.
iin.
1 in.
8
.128
1
14.81
7.40
4.93
3.70
2.96
2.46
2.11
1.85
9
.114
16.69
8.34
5.56
4.17
3.34
2.78
2.38
2.08
10
.101
18.80
9.40
6.26
4.70
3.76
3.13
2.70
2.35
11
.0907
20.97
10.48
6.99
5.24
4.19
3.49
2.99
2.62
12
.0808
23.46
11.73
7.82
5.86
4.69
3.91
3.35
2.93
13
.0719
28.63
13.31
8.87
6.65
5.32
4.43
3.80
3.32
14
.0641
29.62
14.81
9.87
7.40
5.92
4.93
4.22
3.70
15
.0571
33.38
16.69
11.12
8.34
6.68
5.56
4.77
4.17
16
.0508
37.60
18.80
12.53
9.40
7.52
6.26
6.37
4.70
17
.0452
41.94
20.97
13.98
10.48
8.38
6.99
5.99
5.24
18
.0408
46.02
23.46
15.64
11.73
9.38
7.82
6.70
5.86
19
.0359
53.26
26.63
17.78
13.31
10.64
8.87
7.60
6.65
20
.0320
59.24
29.62
19.75
14.81
11.84
9.87
8.46
7.40
21
.0284
66.76
33.38
22.25
16.69
13.35
11.12
9.53
8.34
22
.0253
75.20
37.60
25.07
18.80
15.04
12.53
10.74
9.40
23
.0225
83.88
41.04
27.96
20.97
16.77
13.98
11.96
10.48
24
.0201
93.84
46.92
31.28
23.46
18.77
15.64
13.40
11.73
25
.0179
106.52
53.26
35.50
26.63
21.30
17.78
15.21
13.31
26
.0159
118.48
59.24
39.49
29.62
23.69
19.75
16.01
14.81
27
.0142
133.52
66.76
44.50
33.38
26.70
22.25
19.07
16.69
28
.0128
150.40
75.20
50.13
37.60
30.08
25.07
21.50
18.80
29
.0112
167.76
83.88
55.92
41.04
33.55
27.96
23.96
20.97
30
.0100
187.68
93.84
62.56
46.92
37.53
31.28
26.81
23.46
31
.0089
213.04
106.52
71.01
53.26
42.60
35.50
30.43
26.63
32
.0079
236.96
118.48
78.98
59.24
47,40
39.49
33.82
29.62
33
.0071
267.04
133.52
89.01
66.76
63.40
44.50
38.15
33.38
34
.0063
300.80
150.40
100.26
75.20
60.16
50.13
42.97
37.60
35
.0056
335.52
167.76
111.84
83.88
67.10
55.92
47.93
41.94
38
.005
375.36
187.68
125.12
93.84
75.07
62.56
53.62
46.92
87
.0044
426.06
213.04
142.02
106.52
85.21
71.01
60.87
53.26
38
.004
473.92
236.96
157.97
118.48
94.78
78.98
67.64
59.24
206
PROPERTIES OP CONDUCTOR0.
Specifie sravity 8.102.
Specific resistance at 20^ C. mean 85.18 mierohins.
Temperature coefficient, mean 0007007.
Resiatance per circular mil-foot 314. ohms.
Resistance per lOOO', 1 square inch area . . . .8613 ohms.
This metal can be permanently loaded with current sufficient to raise its
temperature to 600^ C. (1112^ F.) without undergoing any structural chan^
It should never be put in contact with asbestos, however, as this matensl
oauses it to deteriorate rapidly*
Diam.
Diam.
in Inches.
Keai^
est
B.&S.
Gauge
Feet
Resistance In ohms per foot.
In m.m.
at
at
at
at
No.
68° F.
1760 F.
2840F.
4280 F.
6
.1968
4
9
.0132
.0138
.0143
MBO
4
.1772
6
12
X)163
.0170
Mie
.0184
4
.1576
6
15
.0206
.0216
.0224
M36
H
.1378
7
19
.0209
.0280
.0291
.0907
3
.1181
2+
26
.0368
.0382
.0896
J0417
21
.1063
9-
31
.M37
.0456
.0472
JM/n
P
.0864
10
37
.0628
JOBBO
.0670
Mtn
.0686
11
46
.0663
.0679
.0706
.0742
2
J0787
12
68
.0826
.0860
J0892
M¥}
If
.0688
13
76
.1078
.112
.116
.123
1}
.0600
16
104
.1468
.163
.169
.107
1|
jM92
16
160
.2116
.220
.229
.241
1
.0383
18
234
.3306
.344
.366
.376
J
01296
21
416
.6870
.610
.633
.067
.0196
24
937
1.324
1.38
1.43
IJil
American Agent, Thomas Prosser A Son, 15 Gold St., New York C^ty.
-wi
Hside bj DrlTer-^Uurrla IFire Co.
HsMTviaoM, If. jr.
•*B. B." — Resistance per mil-foot at 76" F.
Low temperature coefficient and low thermo-eleotrie effect
against copper. Will not rust.
"AuVANCB." — Resistance per mil-foot at 76** F.
A copper-nickel alloy containing no sine. Temperature
coefficient practically nil.
•*F«RRO-NicKEL." — Resistance per mil-foot at 76* F.
Temperature coefficient per ^ F.
About the same resistance as German Silver, but weighs
about ten per cent less and is cheaper.
830 ohms
204 ohms
170 ohms
.00116
DRIVER-HARRIS RESISTANCE WIRES.
207
vf l»rlY«r»Hw
:
"S. B."
"Advance."
••Ferro-Nickol."
No. B. A &
Ohma per
1.000 ft.
Ohmsp^r
1.000 ft.
Ohms per
1,000 ft.
10
82
28.
2.0
11
40
35.5
2.5
12
51
44.8
3.2
13
64
56.7
4.1
U
82
71.7
5.1
15
103
90.4
6.5
10
130
113
8.2
17
168
145
10.4
18
210
184
13.1
19
260
.226
16.3
20
328
287
20.5
21
415
362
25.9
22
526
460
32.7
23
600
575
41.5
24
831
726
52.3
26
1.060
010
65.4
26
1.828
1.162
85
27
1.667
1.455
106
28
2.112
1,850
131
29
2,625
2.300
166
30
3.360
2.940
209
31
4,250
3.680
266
32
5.250
4.600
333
33
6.660
5.83a
425
34
8,400
7,400
531
35
10.700
9,360
672
36
13.440
11.760
850
37
16.640
14,550
1,070
38
21,000
18.375
1,330
39
27.540
24.100
1.700
40
37,300
32.660
2.120
■ •
• • •
. • «
. • •
208 PROPERTIES OF CONDUCTORS.
oiTMmmx cAS]ftiniv« cajpaoktit ojt
A]ffl» GAllIiKII.
Let Z> "■ dimmeter of wire or cable core in inches.
T — temperature elevation of wire or cable core in * Centigrade.
/ — current in wire in amperes.
r ■■ apecifio resistance of wire in ohms per mil-foot at final tena-
perature.
The following ^>proximate formula give results sufficiently accurate for
practical purposes.
Bare Owrhead Wzrks Out of Doobs.
Stranded : Solid :
Barb Wues In Doors, Expobbd.
Stranded : Solid :
/ « 610
y Z:^. / - 060 y/I^.
SxNOLB Conductor Rubber Coybrbd Cable in Snix Air.
Stranded : Solid j
ijei iwin iTiia * a^^s&^A
/ - 490 y^. / - 530 y ^
SiNaLB Conductor Rubber Covbrbd Lead Sheathed Cable im
Underground Single Duct Conduit.
Stranded : Solid :
/ - 490 y^. / - 530 ^I^.
SiNOLE Conductor Paper Covered Lead Sheathed Cable in
Underground Single Duct Conduit.
Stranded : Solid :
/ - 430 y^. / - 470 ^T^.
* Three-Conductor Rubber Covered Lead Sbeathbd Cable in
Underground Single Duct Conduit.
Stranded :
Solid:
/ - 370 i/^^-
^ r
7-4O0v/^^.
* Three-Conductor Paper Covered Lead Sheathbd Carle in
Underground Single Duct Conduit.
Stranded :
Solid:
/-320\/^^.
7-350 y/^^.
* / is here current per wire.
CAPACITY or WIRES AND CABLES.
NinoHAi. ELBcniiciL Codb.
V'^
c^
^
¥
^^
W
"a^
AmpanuL
AiDptna.
211,800
210
312
l.OIO
ii
,870
<
idetf 0*p|Mr CtmdBt
Natiohu, Ei-ectbical
CODt
B,4&C.
n.'E"'
No. of
StlSBdlU
«s!"ii:'^
Ampffo.
■■■ 111
1.28S
18
.1
B
i?
21
SS
".338
60
60
«igT
73:778
99,064
120
124,628
145
is7%ea
170
198,877
235
127
m win Uie c&rryiajf capainty of any fii
of the TBlot giTBD tn the sbon table.
SIM is to be takso
r
210
PBOPERTIES OF GONDUCTOBS.
Carrjlair Capacity of 1
{From Uehnieal letter of Oeneral Electric Company.)
The following table of earrjring capacity ia baaed on teste of cables in
■till air. Insulation alone A' thick; lead A' to f thick; jute and
asphalt jacket A' thick. Pap«r insulated cables heat S% to 10% more
than rubber insulated cables with same current and thickness of ooverixiga.
Cables require about four hours to reach final temperature.
60% of total increase in temperature in Ist hour.
30% of total increase in temperature in 2d hour.
8% of total increase in tenq>erature in 3d hour.
Cables immersed in water will carry 60% more current with same inc
of temperature, and cables buried in moiet earth about 15% more. Rubber
cables should not be run above 70^ C. Paper cables should not be run aboTS
90* C.
)
Amperes at 30"* C
Amperes at 50^ C
Diameter
Bise.
Rise.
Copper
Core.
Inches.
Bise.
Leaded
Leaded
Braided.
and Jute
Braided.
and Jute
Covered.
Covered.
6 B. dc & Aolid
.162
61
56
76
68
4 B. & S. Solid
.204
85
78
104
94
2 B. & 8. Stranded
.300
133
121
162
146
1 B. A S. Stranded
.325
155
141
189
'170
0 B. 4c S. Stranded
.390
191
174
231
210
00 B. & S. Stranded
.420
218
199
268
241
000 B. ft a Stranded
.476
266
242
326
283
0000 B. ft S. Stranded
.543
320
291
891
352
250000 CM.
.570
355
824
435
892
300000 CM.
.640
414
877
506
456
350000 CM.
.680
460
419
568
607
400000 CM.
.735
512
466
626
564
450000 CM.
.787
562
511
687
618
500000 CM.
.820
606
551
742
668
600000 CM.
.900
604
631
848
763
750000 CM.
1.020
825
760
1016
915
900000 CM.
1.096
940
855
1149
1034
1000000 CM.
1.157
1017
925
1338
1200
1250000 CM.
1.298
1204
1095
1481
1328
1600000 CM.
1.413
1376
1251
1644
1480
2000000 CM.
1.760
1766
1606
2178
1960
HeaiiBC of Cable* la Maltlpla l»ac« Caadait.
The mutual heatins of cables in multiple duct conduit has been hum'
tigated experimentally by H. W. Fisher. The following diagram sad
table shows the arrangement of the conduit system used by him and the
size and kind of cable in each duct. Means were provided for copnectiog
any or all the cables in series and observing the temperature of the eeiw
doctor in each duct.
CAPACmr OF WIRES AND CABUBS.
211
© ® ®
©
© © ®
©
0 © ©
®
Fio. 22.
Number of
Sise B. A B. and
Cable.
ConduotorB.
CM.
Insulation.
A*
000
Jf' and ^' Paper
B
1
600.000
X' Paper
0>
000
X" and A' Paper
D
500.000
X' Paper
E
1.260.000
jC' Paper
F
1,260.000
X' Paper
G
000
j^' Paper
H
000
Rubber
I
1.260.000
A'Papw
A' Paper
J
1.260.000
K
000
Rubber
L
000
A' Paper
* The three conductors of A and C in multiple.
Fisher's restilte are summarised in the following table :
E,F.I,J.
Conductors
Canying Current.
G, H, K, L.. ••■•••■
A, B, C, V, £, Ff If J. ...
SO*" C. Rise.
Conductor.
A.AC.
(G
L
I
E
J
F
B
D
(J
\
Amperes.
130
155
180
600
690
560
636
355
400
60« C. Rise.
Conductor. Amperes,
A.AC.
G
L
I
E
J
F
B
D
180
190
260
766
760
725
690
425
550
An tnq>ectk>n of this table will show that the current corresponding to a
nwtn temperature elevation is in each case less than that given by the
lormulaB on page 206. the difference bein^ from 4 to 26 per cent, depend-
>t conductors in service and the location of the cable
the number oi . . .
in question. It is to be noted that comer ducts radiate heat the best, and
■U outside ducts radiate heat much better than do the inside ducts.
r
212
PROPERTIES OP CONDUCTORS.
per Voot 'Ei9mt Im ftiBirl«*CJoM«l«ctor C«1»le« »«
IHIIereat MAxtmvm TeBftp«ratiir« wltli IMIi«reM«
Amouito or 4
(From Handbook No. XVII, 1906. Copyrighted by Standard Under-
ground Cable Company.)
•
Sise B. A S.
Current in
6
66
81
93
104
114
123
5
74
91
106
117
128
138
4
84
102
117
131
144
153
3
93
114
132
148
161
175
a
106
128
148
186
181
196
1
118
148
166
186
203
220
0
132
162
187
209
228
247
00
149
181
210
235
256
277
000
166
204
235
263
288
311
0000
186
229
264
'298
828
260
Area in
1000 C. M.
300
222
273
315
352
385
416
400
248
316
363
406
445
480
600
288
352
406
456
498
537
000
315
385
445
497
646
587
TOO
841
416
480
688
688
6S6
800
364
446
514
676
628
679
000
386
473
545
610
666
720
1000
407
498
575
642
703
758
1100
426
522
602
674
736
796
1100
446
846
630
706
772
8SS
1300
462
668
655
732
802
866
1400
480
590
681
761
834
90O
1500
496
610
704
788
862
931
1600
512
629
726
812
889
960
1700
629
649
780
887
916
990
1800
543
667
770
862
943
1018
1900
557
686
792
886
970
1048
2000
573
705
813
910
995
1075
Watts lot
it per ft.
Temp. (100
1.81
2.71
3.62
4.52
6.43
6.33
of oond. 128
1.91
2.87
8.82
4.78
6.78
6.69
in«F. 160
2.00
3.00
4.00
6.00
6.00
7,00
The watts lost per foot means the amount of electric energy lost in heat-
ing the conductor and is equal to the product of the resistance per foot of
cable times the square of the current in amp>eres.
The above table is useful in showing the watts lost in heating effect per
foot of cable with dififerent currents, and also in finding the sue of con-
ductor that must be used for a given current and watts per foot loss.
for Two-Condactor Cables the watts corresponding to the dif-
ferent currents must be multiplied by two, and to obtain the currents
corresponding to the watts in the table multiply the currraits given in the
table by .707.
for Vhree-Conductor Cal»Iea the watts corresponding to the
currents in the table, must be multiplied by 3. and to obtain the currents
corresponding to the watts in the table multiply the currents given in ike
table by .577.
CAPACITY OF WIRES AND CABLES.
213
€;«iv«Mt CanyiaiT Capacity mt
C«T«re4 CaMes.
(Fiom Handbook No. XVII. 1900. Gopyrighted by Standard Under-
ground Gabla Company.)
The eurrcnt carrying cai)acity of insulated copper oablei sheathed with
lead depends primarily upon
(a) The sise and number of oonductonti and their relative position.
(&) The ability of the insulating material to withstand high tempera-
tnras and to conduct heat away from the copper conductor, — this latter
being in turn dependent upon kmd of insulation and its thickness.
(e) The initial temperature of the medium surrounding the cable.
la) The ability of the medium surrounding the cable to dissipate heat
with small temperature rise.
(e) The number of operating cables in dose proximity and their relative
Where a number of insulated conductors are under the same sheath,
they are subject to an interchange of heat somewhat similar to that which
takes place when a number of separate cables are laid closely together,
and for that reason each conductor of a multi-conductor cable will nave a
smaller current carrying capacity than a singlensonductor cable. If the
rariouB oonductora are separately insulated and laid to^^her in the form
of flat or round duplex or triplex, thdr carrying capacity will be greater
than if they are laid up in the form <^ two-conductor concentric or thre&-
oonduetor concentric, since the enveloping conductors in the latter forma-
tion seriously retard the dissipation of heat from the inner conductors.
Assuming that unity (1.00^ represents the canying capacity of single-
eonductor cables, the capacity of multi-conductor cables would be pven
by the following:
2 oond. flat or round form,
3 eond. triplex form
.87; concentric form,
.75; concentric form.
.79
.60
The following experiment on duplex concentric cable of 525,000 C. M.
iadiestes clearlv the danger in subjecting this type of cable to heavy over-
ioeds Of even snort duration. The cable was first heated up by a current
cf 440 amperes for 5 hours. An overload oi 50 per cent was then applied,
the resolts In degrees Fahrenheit above the surrounding air being as
follows:
Time from Start.
OMin.
15 Min.
30 Min.
45 Min.
60 Min.
90 Min.
Inner Conductor
Outer Conductor .
LeadCover . . .
70°
55
31
84«
65
35
98*
76
40
111«»
85
45
123*
94
49
142«
108
57
In any eaUe the area over which dissipation of heat must take place is
proportional to the circumference of the conductor or (since the oircum-
loenee varies as the diameter), upon the diameter of the conductor, while
the croas section of the conductor varies as the sauare of the diameter.
Hence the sise of conductor varies much more rapidly than its heat radiat-
iac sm^iee, and in oonsSQuenoe the amperage per sauare inch, or circular
inu of oopper seetion, must be less for large size oonauctors than for small,
in order to have the same rise of temperature under the same conditions.
Hie nsoal formula for carrying capacity.
Current »
(diam. of Cond.)*
A constant
aeoount of this fact but not to a sufficient degree, and we find that
for caUes as ordinarily used in underground work, a more correct expression
li the following:
Current — (d"Mn. of Cond.)t
A constant
214
PROPERTIES OF CONDUCTORS.
Rubber iiuulation ia a somewhat better heat conduetor than dry or
saturated paper, and therefore, when applied to the same siae eonduetor ia
equal thickness, will permit of a larger current flowing in the conductor fer
the same rise of temperature above the surrounding air. On the otbcrl
hand, rubber deteriorates much more rapidly at high temperaturee thaa
saturated paper, and while this disadvanta^ is apparently oompenaated
for up to about 150^ Fahrenheit by its superior heat dissipating qualities, at
higher temperatures deterioration takes place and becomes so serious tnat
its value as an insulating medium disappears in a comparatively short tixncl
As the thickness of insulation is increased, the temperature of the con-i
ductor, with any given current flowing graaually, increases and tbereforei
the current oarrsring capacity becomes reduced. The reduction in capacity
however, is not very great, being in the ratio of about 03 for H instuation
to 100 for A insulation, so that the values in the table given below ahould {
be slightly cfecreased when greater thicknesses than A are used.
As It is the final temperature reached which realiy affects the cajryincl
capacity, the initial temperature of surrounding medium must be takeefi
into account. If, for instance, the conduit system parallek steam or ha%\
water nuuns, the temperature of ISO** F. (which we have assumed in th«|
table on page 215 to be the maximum for safe continuous work on cables]
will be reached with lower values of current than would otherwise be
case; and as 70^ is the actual temperature we have assumed to exist in
surrounding medium prior to loading the cables, any increase over
must be compensated tor by reducing the current carried.
For rough calculations it will be safe to use the foUowing multiplicn to|
reduce the current carrying capacity i^ven in the table on page 2lo to thej
proper value for the corresponding mitial temperatures:
Initial Temp. .
70
80
90
100
110
120
130
140
150
Multipliers . .
1.00
.83
.86
.78
.70
.60
.48
.34
.00
The ability of the surrounding medium to dissipate heat, directly affeets
the carrying capacity of the caDles, as with the same current the cable
might be comparatively cool tf laid in good heat conducting matoial such
as water, and dangerously hot if laid in poor heat opnduol-
O^^-^y^^ ing material such as dry sand. Ordinary conduit Bystema
I of clay or terra cotta oucts laid in cement, dissipate heat
^ J fairly wdl, the outside ductSL however, bemg much more
OV-*'^^"~K^ efliaent in this function than the inner ones, so that an ideal
I system, from this point of view, would consist of a single
^ J horisontal layer of ducts. As this would require an enormoos
O^^ • C width of trench and considerable inconvenience in handling
I the cables in manholes when many cables are to be installeo.
^ J we would suggest the form shown in Fig. 28 as being more
O^^^^FTTTx practicable.
T( ] I Where more ducts are required, the vertical section shown
JC^J could be easily duplicatecLa considerable space, however,
"^"^Ti^ being left between them. With this arrangement, the cany-
Fig. 23. {Qg capacities given in the table on p. 215 could be somewhat
increased.
When a number of loaded cables are operating in dose proximity to one
another, the heat from one radiates, or is carried by conduction, to each of
the others, and all raised in temperature beyond ^„^^^ — ^
what would have resulted had only a single cable fVSY/^^Y/'^ 1/^^
been in operation; and if the cables occupy ll^lv^I^H^
adjacent ducts in a conduit system of approxi- S— A.i ^ ^ (
mately square cross section laid in the usual way, (/Ok | /TnT/^ T /^^
the centrally located cable or the one just above I V5/l VC/lL-zlw
the center m large installations (A in Fig. 24) ^ ^ ^ ^
will reach the highest temperature. This is equiv-
alent to saying that its carrying capacity is
reduced, and while this reduction does not amount
to more than about 12 per cent (as compared piQ. 24.
with the cable most favorably located, — as at
Z>, Pig. 24) in the duct arrangement given, it may easily assume much
greater proportions where large numbers of cables are massed together.
©MoTq
CAPACITY OP WIBES AND CABLES.
tatn b* Wed, lbs unncB nurriag npaeity mny M takce
Kiir Hopv «H of oonduetor,' and for isbls of > clvai
■nnruiK eapscitics of all abW evao thou^ plaoad ia M
■ b* Rtnssiled by the following fisuna, takiiiB unity aj
mpm avaty <d tour ablu:
CwTwat CarcTJar 0>a«clH«» f»r Coble*
a^ fTatU l.M« p«r Km.
kvuM giogls eonduotor paper i-.iiT.ijH lead
B> adi of four equally loadad giogle n
^^ «^n tha initial tampentun do«g oot aiOMd 7U" tr„ ttae nuauaum
■taBpantun for eontinuoui opsntion beioi takan at 1«)° F.
Wm HandbDok No. XVII. lOOS. Copyri(h(ed by Studud TToder-
fmund Cable Compaay.}
as;
Siw
Ampwea.
Watti*
toot per
.M.
C. H.
,£•¥.
87
300,000
333
4 32
03
400.000
09
.01
IS
,1S
M
.M
e07
650
:7i
.1 00'
ess
.88
00
710
.01
1,: 00
TW
3t
. .: 00
S90
:25
54
00
M7
.37
S95
0.49
'.■ 00
033
M
t^ «
•TO
«:Tt
40
00
toio
.86
OB
.900,000
99
Z.000.000
1085
:o9
at* Uia amount of oiersy whioh la traiuformed
t be diMlpated. It ia wEst is usually called the
lytulnctor/ tha DURcnt values Elvao: and for A
<otiTe oooduotor at a temperature of 150° T.
eompiled from a loni seriea of testa made by ua
{lacan Falls Power Company, the sonduil system
in Fig. 24. The dusla ware ol terra cotta with
i
216
PROPERTIES OF CONDUCTORS.
SecoHiHieadcd Power Cmwwjtmg Capaclt;^
of ItoUverMl fiaovjirj, Xltroo-ConAactor
Calilos.
Itr i» KllowaiJ
, Throo-Pli«oo 1
(From Handbook No. XVII. 1906. Copyrighted by Standftitl Under-
ground Cable Company.)
Sixe in
Volts.
B. & S. G.
1100
2200
3300
4000
6600 1
11000
13200 1
22000
Kilowatts.
6
02
183
275
333
549
015
1098
1831
5
100
217
326
395
652
1087
1304
2174
4
130
200
300
473
781
1301
1562
2003
3
154
309
463
562
927
1544
1854
3080
2
179
S58
586
650
1078
1788
8146
8878
1
209
418
626
759
1253
2088
2506
4178
0
240
481
721
874
1442
2402
2884
4805
00
279
558
836
1014
1674
2788
3347
5577
000
322
644
965
1172
1931
3217
3862
6435
0000
S7S
744
1116
1S6S
SSSl
8717
4468
7488
250000
413
827
1240
1503
2480
4132
4060
8264
mairl« Coadnctor Gable*
, JL.C
. or D
. G.
Volts.
Siiein
B. & S. G.
125
250
500
1100
2200
3300
6600
11000
Kilows
kttS.
6
8.0
16.0
32
70
141
211
422
704
5
9.5
19.0
38
84
167
251
502
836
4
11.4
22.8
45
100
200
300
601
1001
8
18.6
87.0
64
119
838
886
718
1188
2
15.6
31.2
62
138
275
413
825
1375
1
18.3
36.5
73
161
321
482
964
1006
0
21.0
42.0
84
185
370
554
1109
1848
00
24.4
48.8
97
215
429
644
1287
2145
000
S8.1
66.S
lis
848
496
748
1486
8478
0000
32.5
65.0
130
286
572
858
1716
2800
900000
40.4
80.8
162
355
711
1066
2132
3558
400000
48.8
97.5
195
429
858
1287
2574
4200
500000
56.3
112.5
225
495
990
1485
2970
4M0
600000
68. 1
186.S
868
656
nil
1667
8888
8886
700000
69.8
139.5
279
614
1228
1841
3683
6138
800000
75.9
151.8
304
668
1335
2008
4006
6677
900000
81.3
162.5
326
715
1430
2146
4290
7150
1000000
86.9
173.8
348
764
1529
2294
4587
7645
1100000
92.5
186.0
870
814
1628
2448
4884
8140
1200000
97.5
195.0
390
858
1716
2574
5148
8580
1400000
107.1
214.3
429
943
1885
2828
5656
9427
1500000
111.9
223.8
448
985
1909
2954
5907
9845
1600000
116.6
tss.s
467
1086
8068
8078
6168
10888
1700000
121.3
242.5
485
1067
2134
3201
6402
10670
1800000
126.3
252.5
505
nil
2222
3338
6666
11110
2000000
135.6
271.3
543
1104
2387
3581
7161
11935
These tables are based on the recommended current carndng capacity dt
cables given on pMtge 215. A power factor » 1, was used in the calcula-
tion and hence the values found in the last table are correct for direct
currents. For alternating currants the kilowatts given in both taUes
must be multiplied by the power factor of the delivered load.
FUSING EFFECTS OF ELECTMC CURRENTS. 217
Fvsnro XFVJBCx* ojf kubcvmo cviuunriw.
By W. H. Preeoe, F. B. S. See " Proo. Roy. Soc.," toI. xUt., March 15, 1888.
The Law — 7 r= cufi , where /. current ; a, constant ; and d, diameter —
ii strictly followed; and the following are the flnal yalnes of the constant
*'a," for the different metals as determined by Mr. Preeoe : —
Copp« . .
Alomlnnm
Platinum
German Silver
Platinoid
Iron . . •
Tin . . .
Alloy (lead and tin 2 to 1)
AliOJi
Inches.
10,2M
7,585
5,172
6,230
4,750
3,148
1,642
1,318
1,379
Centimeters.
2,530
1,873
1,277
1,292
1,173
777.4
406.5
326 JS
840.6
Millimeters.
80.0
69.2
40.4
40.8
37.1
24.6
12.8
10.8
10.8
Cable CSlTiBs*
tte ]MaHiet«m of Wires mt Variooa Mnierl*
^ITklcM frill He I'vaed kj a Current of Olrea
Mreafftb.— W.H.Preece,F.B.S. d=-/^^*/'
- i^r
^
Diameter tn Inches.
3 .
A
^
II
Silver.
6230.
a-*
31
|y
•
n
§11
5«
|!
u\\
111
it
III
3©
1
^(Wffl
O.0026
O.0083
O.O0R3
O.O086
0XNM7
0.0072
0.0083
0.0061
2
OuO094
0.0041
0.0063
0.0063
0.0066
0.00^/4
0.0113
0.0132
0.0128
S
OU0944
OJ0064
0.0070
04W69
0.0074
0.0097
0.0149
0.0173
0.0168
4
ftflffiCff
Oi»66
O.0064
0.0084
0.0089
0.0117
0.0181
0.0210
0.0203
6
(MUffi
CM»76
0*0008
OJ0097
0.0104
0.0136
0.0210
0.0243
0.0236
10
OiNM
0.0130
0.0165
0.0154
0.0164
0.0216
0.0834
0.0386
0.0876
tf
<Mn29
Oi»fi8
0.0208
0.0202
0.0215
0.0283
0.0497
0.0606
0.0491
»
OjOUa
0^191
0.0246
0.0245
0.0261
0.0843
0.0629
0.0613
0.0686
S
OjOlgl
0.0222
0.0286
0.0284
0.0903
0.0898
0.0614
0.0711
Oj0690
38
fltjfflMg
0.0250
O.0323
04»20
a0342
0.0460
0.0694
0.0603
0.0779
as
OJ0SS7
0.0277
0.0368
0.0366
0.0379
0.0498
0.0769
0.0890
0.0864
49
OJQMS
0.0903
0.0391
0.0388
0.0414
0.0645
0.0640
0.0973
0.0944
«
Oj02B8
0ii328
0.0423
0.0420
0.0448
0.0689
0.0009
0.1062
0.1021
»
0j0288
Oin62
0.0454
0.0460
0.0480
0.0632
0.0975
0.1129
0.1096
m
0iQ326
0^1397
0.0613
O.O609
0.0642
0.0714
0.1101
0.1275
0.1237
10
O-Offffff
0.0M0
0.0668
0.0664
0.0601
0.0791
0.1220
0.1413
0.1371
m
0JB94
0.0481
0.0621
0.0616
0.0657
0.0864
0.1334
0.1544
0.1499
»
ojotas
0.0620
0.0672
0.0667
0.0711
0.0936
0.1443
0.1671
0.1621
100
QMBI
0iffi68
0.0720
0.0716
0.0762
0.1003
0.1648
0.1792
0.1739
139
OL0616
0JM30
O.0814
0J06M
0.0861
0.1133
0.1748
0.2024
0.1964
149
OJBSn
O.O098
0.0002
0.0696
0.0054
0.12B5
0.1937
0.2243
0.2176
m
ff^flff
0X^763
O.0086
0.0978
0.1043
0.1372
0.2118
0.3462
0.2379
rm
OUO078
0.0626
0.1066
0.1068
0.1128
0.1484
0.2291
0.2652
0.2673
m
0J1T86
0.0686
0.1144
0.1135
0.1210
0.1682
0.2467
0.2846
0.2760
2B
OJ079i
OJ0868
0.1237
0.1228
0.1309
0.1722
0.2658
0.3077
0.2986
:«•
a08U
0.1028
0.1837
0.1317
0.1404
0.1848
0.28bl
0.3301
0.3208
^zs
0i»B7
0.10B6
0.1414
0.1404
0.1497
0.1969
031R8
0.3518
0.3413
m
' -
OljfflffO
0.1161
<U408
0.1487
0.1686
0.2086
0.3220
0.3728
0.3617
1
21S PBOPERTIES OF CONDUCTORS.
By Harold Pbndbr, Ph.D.
The aooompanying oharta* (No. 1 for loii^ spanB, No. 2 for short spaiMi}
enable one to determine without arithmetical computation the variatiaa
ol the tension and sag in copper wire spans with the temperature and resoK
tant load on the wire. Similar charts can be readily prepared for wires «f
any material.
The symbols used in the discussion below are as follows:
m -" wei|iit of wire per cubic inch in pounds,
a -> coefficient of linear expansion of wire per degree Fahr.
M ■" modulus of elasticity of wire (pounds — square indi).
P •* ratio of resultant of the weight of wire, the weight of sleet and the
wind pressure to the weii^t of wire.
I — length of span in feet.
( — rise in temperature in degrees Fahr.
T <-• tension in thousands ol i>ound8 per sc^uare inch.
D a- deflection at center of span in feet in direction of resultant force irtieo
points of suspension are on the same level.
8 •" vertical sag at center of span in feet when points erf support are oa
the same level.
The lines on the charts are plotted as follows:
The hyperbolic curves on the ri^t have the equation y » f^J iriiere y
is the ordinate and T the abscissa. A curve is plotted for p •* 1.0, 1.2,
1.4 . . . 4.0. The value of p for each curve is indicated at the top of the
chart. It is to be noted that the horisontal distance between these curves
at any level is directly proi>ortional to the increment in the value of p.
These curves are independent of the material of the wire.
The inclined strai^^t lines have the equation y » T-jr= — ^ T. For a
given matmal the equation of these lines depends only on the length of the
span. The lines on the charts are drawn for copper wire for whidi m ■-
0.321 and Af ■-> 12 X 10". The corresponding length of span is indicated
on the right-hand margin ci the charts. For any other material, the line
for a given length of span will have a different slope.
The temperature scale on the X axis to the right of the origin is laid off
so that X — Ma t. The scale given on the chart is for oopper, for whidi
Jlf » 12 X 10« and a » 9.6 X uT*. This scale will be different for any
other material.
The parabolic curves on the left of the chart have the equation D -> 0.0015
m P ^fy, where D is measured off from the left of the oripn. For a gives
material these curves are fixed by the length of the span. The curves
p;iven on the chart are for copper, for which m — 0.321. The oorreepond-
ing lengths of span are indicated on the curves. These curves 'mil be
different for any other material.
Rules for tlie 17e« mt t1i« CMarta.
Given: A span of length I and the points of support on the same level,
tension Tt; ratio of resultant force to weight of wire^ pi; to find the tension
T when the temperature rises t degrees and the ratio of resultant force to
weight of wire changes to p (for example, sleet melts off).
At the point 1 (Pig. 27) on the curve corresponding to pi and having
the abscisiia 7^i, lay off 12 <» the ordinate of the point 3 on the line corre-
sponding to { having the abscijisa t on the temperature scale.
* These charts were devised to obtain a graphical solution of the equa-
tions deduced by the author in an article in the Electrical World for Jan.
12, 1907, Vol. 49, p. 99. The present article also appeared in the BlectneiU
World for Sept. 28. 1907.
i
WIRE SPANS.
219
Throusfa 2 draw a line parallel to the line I : the abecissa of the point 4
Miere this line outs the curve oorresponding to p ia the tension T at the
lem^eratuFe t when the ratio of resultant force to weight of wire is p. The
■hsciasa of the point 5 where the horixontal line through 4 outs the para-
bolic curve corresponding to { gives the corresponding deflection D at the
cater of the span in feet. Instead oi actually drawing the straight line
M. a pair of oompassee may be used; i.e., lay on the distance 12. then open
the compasees until the lower ooint touches the straight line I; then keep-
ing the compaaees vertical, diae the lower point along 2 until the upper
point intereeets the curve corresponding to p. If < is negative, i.s., if the
temperature decreases, lay off 12 in the opposite direction. To determine
D with greater accuracy use the formula
D - .0015 m P ^ •
Fig. 25.
C«lc«latloM 9f p.
Let w — wel^t of wire in pounds per foot.
The weif^ttt ideet (and hemp core, if any) in pounds per foot of wire is
w, - 0.314 W - d*) + 0.25 <V,
where d is the diameter of the wire, di the diameter over sleet and dp the
<fiaraeter oi the core, all in inches.
The wind pressure in pounds per foot of wire is *
10S - 0.00021 F2 du
where V is the actual wind velocity in miles per hour; di — d in case of no
rieel. The relation between indicated wind velocity (as given by U. S.
Weather Reports) and actual velocity is as follows:
The ratio p is then
Indicated Velocity.
10
20
30
40
50
60
70
80
90
100
Actual Velocity.
9.6
17.8
25.7
33.3
40.8
48.0
55.2
62.2
69.2
• 76.2
-/O-^M^)'
* H. W. Buck in Transactions International Electrical Congress, 1904.
r
220 FROPEBTIES OF CONDUCTORS.
1 <
ii i
222 PROPERTIES OF CONDUCTORS.
Oalcnlatfon of V«rMcal Aar.
In case of no wind the vertical sag S is the same as the deflection D,
The wind pressure gives a horizontal component to the resultant force si
that the vertical sag when wind is blowing is,
5-
D
v/^ - (i^r
Exampls: A No. 00 stranded copper cable is to be strung in stall air
at 70° F. between two points on the same, level 800 feet apart, ao that at a
temperature of lero degrees Fahrenheit, with a coating of sleet i inch thi^
all around and wind blowing perpendicularlv to the cable at o5 miles aa
hour factual velocity) the tension in the cable will be 30,000 lbs. per tn.
in.; (1) at what tension must the cable be strtmg and (2) what will be the
vertical sag at stringing temperature, i.e., 70^ also (3) what will be the sag
at sero temi>erature when the cable is coated with i-in. of sleet and ^rina
is blowing with a velocity of 65 miles an hour, and (4) what will be the sag
at a temperature of 150°, in the still air ?
We have
w -0.406
101 - 0.314 (filS* - 0418*) - 0.426
tDi- 0.0021 X 66* X 1.418 - 1^.
Therefore, at sero degrees with wind and sleet,
. //, ^ 0.425V . /1.28 V « ^«
(1) Measure off with compasses, on chart No. 1, the vertical dtstaaee
from t — 70 on JT axis to the straight line corresponding to 2 = 800. Lay
this distance off vertically above the point on the curve corresponding to
p « 3.72 having the abscissa T — 30. Keep the upper point fixed, open the
compasses until the lower point touches the line I -■ 800; then, keepmg tiw
compasses vertical, slide the lower point along the line I » 800 until the upper
I)oint intersects the curve 0 « 1 at 7 — 8.d5: the cable must therefore be
strung at a tension of 8950 lbs. per so. in. (2) The abscissa of the point
on the parabolic curve I — 800, having the same ordinate as the point
corresponding to p « 1 and T *- 8.95 is I> «- 34.4 feet, which is the vertical
sag S, in still air at 70° F.
(3) The deflection at sero degrees with sleet and wind is the abscissa
of the point on the parabolic curve { — 800 having the same ordinate as
thepoint corresponding to po — 3.72 and To — 30. i.e., Dq — 38.2 feet.
The vertical sag is
8 - 3^-^ - 21.afeet.
\/^ - CiD"
(4) to find the sag at 150° proceed as under (1) and (2) taking ( - 150.
The sag will be found to be 5 — 36.8 feet.
WIRE SPANS. 223
Wire /iBspeadMl fToat Palate mot on tbe BtiWM ILmrmii,
The charts also apply directly to the determination of the change in
Uoiion in spans when the {Mints of support are at different heights. In
Ihis case, howevar, the vertical sag iSi ^ — deflection in case of no wind)
below the hij^eet point of support is given by the formula
5.-s(i + A)'
where h h the difference in height of the two points of support, and 8 is the
mtiesl ng for a span of equal length, but points of support on the same
^erd: 8 is calcmlaten by the formula given above, t.e..
5-
V \io + tPi/
D befais the deflection, taken directly from the chart, for a span of equal
iCDgth but points of support on the aame level; in case of no wind 8 •» D.
The distance of the point of maximum sag from the highest point ot support
2V ^ 4 8/
When k is greater than 4 S the lowest point of support is the point of max-
raom sag. i^., the lowest point in the span.
Saompie; In the example given above, suppose the difference in height
of the points of support is 20ieet : Then (1) the tension at 70° will stiU be
80S0 lbs. per sq. in. (2) The corresponding vertical sag at 70** in still
■ir for points of support at same levd is 34.4 ft., therefore, for the span
tmder consideration the vertical sag from the highest point of support ie
(3) The vertieal sag at sero degrees with sleet and wind for points of
npport on the same level is 21 ft.; therefore, for a 20-ft. difference in the
Bo^t of points of support the vertical sag from the highest point of sup-
port is
(4) The vertical sag at a temperature of 150°, for points of support on
the lame levd is 36.8 ft.; therefore, for a 20-ft. difference in height of the
VmU of support the vertical sag from the highest point cdF support is
The aeeompanjring table, giving the value of T and p for various values
of y * Usj will be found useful in plotting the hyperbolic curves in case one
to make charts on a larger scale than those given herein, or similar
cherts for wires having different con.itants. The other lines are readily
plotted from the equations given above.
224
■»
1
0
I
9
1
>
8
i
^
8
1
I
I
9
&
•8
9
2
00
CO
CO
CO
00
o
o
«
09
O
00
N
9
>
I
PROPEBTIES OF CONDUCTORS.
Sr-o (D*-io iHcor- ooioo r«<0<D moo o^c«
■ea
OOOft^ C9>C
^ SSS I^SS SSSS 9SS S&{3 sss ss
8»3 SS8
otoftiH iHr-o >o<-4b- fHe>4<« oo*-) e«o
r-4 iHr-irH 0<nS COCOCO 9<<I<S SSS t^SS SS
oKa» cotoo 0010(0 ^a»o e^icak a»oot«> Oioa» oco
00 00 Oft
;:ss S^^ S3S 39S SSlg f^SSS ss
Sci^ t»wo 3o^ t»oo ootiH oou)^ oooo «»o
h>aoaft oc^r^ c»^«p odih^ oocqoq mr«e4 ootot^ r«ei
r^^r-t *HC«cl cicoeo m^9 iSioo Sh-S S<
OMO O0eoe« <DiH^ 0«>«D C9«4
i^b-00 oe^cD
S2S ^^^ ^^n ^^"Qi S2S St^SS S9
eoc>)o
OtoQO OkvHiO
1-i-H fHC404
"*^^0 iOI^^ ^h-00
St-s" eoooci h-'Q'<^
040405 coco^ ^SSttb
0^'« 901
^F>K> ooioo i-<ooto
VDCDb* OOO^
»-i»-iOI
t<*<DO eoi-4«o cooovH
nnS w«» 5^13
0(D-« too
«0MO9 OQiQ
00 CO 04
ooaft^3
S8?
I0>
iOXO)
Ot»0 rH<DX WOftiO
^sis ini 4^^
0*Hf4 C^CQ
ciQor« c«0
ioSS<D 00^4
t^04O
CO 00 CD
u)00
r-oo'oi
I to 1-4
coco 00
CO 0)0
S04S
000 A
COCOCO
OtCDOO
eo9'^
Ot^Q 9C0
^*»o«o
Scoo
<O00iH
- .2500
04IO«0
S»H«
OOOM
f-«o5oi
00 01 01
eoco^
O0400 <D'<f
m ii
^0610
-^'■^'10
OKQO
CO too
iO^(
ot^o
ICO
i-lTflO
SS8
«>«o'
"^00 CO
<ooo»o
cocora
OtN.«0 C9'«
oih>a
ocoS
^^^
sss
loooi
OftCOr^
eob-oo
loo'oo'
1F-I04IO
O09C0 lOOOO QCf>«Q
vHi-ir^ ^^^M^^ ^0«04
lo^a
OC4IO
O)i0
coco^
id CD 00'
"^i-ir^
«coo«
04^04
04«-iQ
«0«DO
CO^CO
06b-«D
C0O04
Oooco coo
OltOi-i
coco^
Sri
2§2
CO CO CO
9^S
^loV
ssr
lb-
xoao
S?28
ior«Q
^ooo
co<
idxoft
fHf-oO
Ocoi-< coo
S»HO
coco
^o«
4o
SSP
CO
oio4co
^S8
co^co
0400
0»-^04
<ooo*o»
1-1 OiO
0004
04a>h-
■*"*0»
r^
900 O)
ooiOco
000^
»-l04O«
0000
^SSco
at'
eg 00
r^g
s^r
1^
04*04 04
OOOQ
»Ht^O
CO CO id
Koco
idt^'t-'
IOC9Q
^»-iO
odoio'
00 -^"^
^0»»H
fMOl^
ooSSS
id 40 00
O-^oo
CON
t« ^040
^r-co o^^ fiSSS^ i-iihS
eqr-iiH «hoo 000 000
.100
»io 00
18 si
WISE SPANS.
i
Orculai Mils
Fm. 28. — Tbetop bounduT of eaoh mma diunm is dnwD for
ul(10° F>hr.: the bottom Vmndsry line forO°. Far other lenL,
mterpolftte or exterpoLatA proportionately. For mecluiDictU reuioas it
■at raooimiiaiided to itring JAri^er ciiee of wire tlun appear in mny c]of
^■B diuimm, ■-^"' '- ■' — **-^ — ■-- -' *!-— ^- 1
226
PROPERTIES OP CONDUCTORS.
Ilellectloas Im Veet
of fttnuided
•tiU
H. W. Buck.
Wire stnmff so that the mudnmm tanston at mtnlmnm temperatDre of
Qo F with wind blowing »t 06 milM per bow (Mtaal Telooity) will be 14,009'
Ibe. per iqiiare in^.
Bpenin
Feet.
Area
of Wire
inCir.
Mils.
1
Degrees Fahrenheit Rise above Minimum Temperature.
0«
2ff>
40'*
60**
80**
lOO'*
120*
140*"
150"
200
558.150
266.400
132,300
.42
.45
.46
.51
.52
.55
.66
.66
.60
.83
.85
.92
1.07
1.13
1.30
1.57
1.65
1.82
2.20
2.27
2.45
2.76
2.80
2.95
2.97
8.03
3.10
400
563.160
266.400
132.300
1.80
1.95
2.20
2.20
2.42
2.75
2.70
2.90
3.40
3.35
3.70
4.20
4.15
4.50
5.10
5.05
5.45
6.00
6.00
6.40
7.00
6.90
7.35
7.85
7.20
7.78
8.50
600
558.150
265.400
132,300
4.3
5.1
6.2
5,1
6.1
7.2
6.0
7.1
8.4
7.0
8.2
9.7
8.2
9.5
11.0
9.5
10.8
12.2
10.8
12.0
13.3
11.9
13.1
14.4
12.5
13.6
15.7
800
553.150
266.400
132.300
8.4
10.3
14.0
9.5
11.7
15.4
10.8
13.2
16.0
12.3
14.7
18.3
13.8
16.4
19.6
15.4
17.7
29.0
16.9
19.1
22.2
18.3
20.4
23.4
10. 0
21.5
25.5
1000
553.150
265.400
132.300
13.9
18.6
26.0
15.6
20.3
27.6
17.8
22.0
29.0
19.1
23.8
30.5
20.8
25.5
31.8
22.5
27.1
33.1
24.2
28.6
34.4
25.9
30.0
36.8
26.7
31.5
37.5
•m XmcIm
of AtnuidoA
•tin Air.
H. W. Buck.
iriro tM
Wire stnmg go that the maximum tension at minimum temperature of
0^ F with wlna blowing at 06 miles per hour (aotual Teloeity) ml be 14/no
lbs. per square inch.
Gsloulatiions made for No. 2 B. and S. stranded conductor, but it is safe
to follow this table for all sixes of cable, for the lar^ sixes will ha.v9
slightly smaller deflections without exceeding their elastic limit on account
of their greater relative strength.
Decrees
Fahren-
Length of Span in Feet
r
heit Rise
above
Minimum
200
180
160
140
120
100
Temp.
0
6.3
5.3
4.2
3.1
2.2
1.7
10
7.0
5.7
4.5
3.4
2.4
1.8
20
7.8
6.4
5.1
3.8
2.8
1.9
30
8.8
7.3
5.8
4.6
3.2
2.2
40
10.2
8.4
6.7
5.2
3.8
2.7
50
12.0
9.8
7.8
6.4
4.6
3.3
60
14.0
11.6
9.4
7.5
5.6
4.0
70
16.5
14.0
11.5
9.2
7.0
5.2
80
19.8
17.0
14.3
11.4
8.9
6.8
90
23.1
20.0
16.8
13.8
10.3
8.8
100
26.6
23.3
20.0
16.6
13.1
10.8
110
29.8
26.6
23.0
19.5
16.6
13.1
120
33.5
29.8
25.8
22.2
18.7
15.2
130
36.8
32.8
28.7
24.5
20.8
17.2
140
40.0
35.8
31.6
26.8
22.8
18.8
150
43.0
38.4
33.6
29.1
24.8
20.3
DIELECTRICS.
227
Valves of SmcIIIc Xsd«ctfve Ciftpaciljr •f
Vartoo* iMelectfiok
NaD-eonduetins materials or Izwnlaton are called dieleetriea. Tbe di-
veetxie eoostant or speeifio indiietlve euaeity of a dieleotrie is the ratio
of tile capacity of a eondenser havinc the apace between its plsAcs filled
vith this substance to the cmMtdty of the same condenser with this spaoe
filled with air.
AD gases and vacuum 1.00
Glass 3to8
IVeated paper used in manufacture of power cables 2 to 4
Poroelain 4.4
Ebonite 2.5
Outtanpercha 2.6
Pure ^va Rubber 2.2
Vulcanised Rubber 2.5
Paraffin 2.3
Rosin 1.8
Pitch 1.8
Wax l.«
Mica 0
Water 80
Tupentine oil 2.2
Petroleum 2
of IHelectiica a* abo«t Mr> C.
I are approximate value^ the resietance of dielectrics varies greatly
vith their punty and method of preparation.
Material.
Ebooite
Glsa» flint
GtasBk ordinary
<jtitka-percha
lfie»7T
{ficsnite cloth . . I ! . !
wcsnite paper
Oaasbeetos
Olhreoil
Onkerite (crude)
raiMr, parchment
I^^lcr, ordinary
Treated paper used- in manufacture of power
cables
Paraffin ....•
Paraffin oil
Bhdlse
Vukaniaed fiber, black
Vokanind fiber, red
Vuleaaiied fiber, white
Wood, ordinary
Wood. para£Bned
Wood, tar
Wood, walnut
Resistance in
Resistance
Millions of
in Millions
Megohms per
Cubic Centi-
of Meg.
ohms per
Cubic Inch.
meter.
14
5.22
28.000
1.100
20,000
800
90
80
450
180
80
30
2.500
900
300
120
1.200
600
850
315
1
0.4
460
180
0.03
0.01
0.05
0.02
10 to 20
4to8
24.000
13.000
8
3
9.000
3,600
68
27
10
4
14
6
600
250
3.700
1.500
1,700
670
60
20
{
228 PROPERTIES OF CONDUCTORS.
The wistionB in reaistance of dieleotrics with temperature is muoh mon
rapid than in the case ol mf»tal8. The variation can be exproMed by an
exponential equation.
fio ■• R/i •
Where R9 ■■ resistance at standard temperature.
A| « resistance at tempo'ature diflPerins t degrees from standard
temperature.
t — temperature,
a -■ constant depending on the material.
For gutta-percha, I in <* C a - 0.88
For pure rubber, < in ** C a « 0.06
For other substances, the processes of manufacture vary too widely to
permit the establishment of temperature coefficients.
IMelectrlc Atresir^ of Mnawlattagr HEatorlala.
C. KiNEBRumncB.
Let V >■ Voltage required to puncture a given tluokness of material.
V <> Volts required to puncture a sheet of material .001 inch thiok.
t "■ Thickness of the material in thousandths of an inch.
For aU the materials given in table below, ezo^t pure para.
For pure para,
For all the materials jD^iven below, except ordinary paper and impreg-
nated paper, tlie pimctunng voltage is the same for a solid sheet of matorial
as for a sheet built up of thin layers. In the case of ordinary paper and
impregnated paper the puncturing voltage is proportional to the number
of layers ; t.a., V "■ ntfVf', where n is the number of layers and t the
thiclmess of each layer.
Punaurino Voltaget for Sheet .001 in, thick (v.)
Presspahn 117
Manila paper 56
Ordinary paper 37
Fiber 67
Varnished paper 207
Red Rope paper 239
Impregnated paper 107
Varnished linen 260
Empire cloth 201
Leatheroid 73
Ebonite 082
Rubber 602
Gutta-percha 464
Fktra 370
I>I£L£CTRIC8. 229
The 'vmloM in the preeedinc table are for ieeta made under the foUow-
ins oonditioTui:
1. ESeetiodee, flat disks with round edges 1.5 inches in diameter.
2. Pressure on deetrodes 0.5 pounds per square inch.
3. Voltage curve sinusoidal.
4. Frequency of the alternating current between 20 and 76 oyoles per
second.
6b Temperature 17* C, humidity of the air about 70 per sent,
d. iPniiure applied for 16 minutes.
Pure rubber is a liquid gum having a spedfio gravity of .015. The
mUser of eommeroe is obtained by coagulating this gmn by various means,
the zDoet approved method being by the hot v^;x>r rising from a smudge
madefinom oily nuts. Rubbers prepcved in this way are called "Para"
rubbers; Ftea is the name of a province of Brasil which supplies a large
quantity of this kind of rubber. Vulcanised rubber is a mixture of this
lypegTiletiwI gmn, thoroughly cleaned and dried, with sulphur. Pure rubber
deieriocBtes rapidly, whereas vulcanised rubber is oomt>arativelv stable,
and at the same time retains the properties which make it valuable as an
«'*«"'r*i"g material. The amount of sxilphur present varies from five
to twenty per cent of the entire mass, the amount determining the hardness
of the proauet. Rubber with a large admixture of sulphur is called vari-
oolv *Miaid rubber," "vulcanite" or "ebonite." Vulcanised rubber is
asea largely for insulating cables of all kinds.
loaa for 30% Rvbber laavlattav Cobs;
AdopUd 1906, by the following wire manufacturers:
Ameriean StttA A Wire Go. Indiana Rubber A Ins. Win Co.
Eleetrical Works. National India Rubber Co.
Bishop Gtttta Pereha Co. New York Ins. Wire Co.
Cenanian Qen. Electric Co. John A. Roebling's Sons Co.
Creeeent Ins. Wire A Cable Co. Safety Ins. Wire A Cable Co.
General Eleetrie Co. Simplex Electrical Co.
Hasard Mig. Co. Standard Underground Cable Co.
India Rubber A Gutta Pereha Ins. Co.
The eompound dial! contain not less than 80% by weight of fine dry
Fsxm n^ber which has not previously been used in rubber compounds.
The compoeition of the remainiag 70% shall be left to the discretion of the
> — The vulcanized rubber compound shall contain not more
than 6% by weight of Acetone Extract. Tor this determination, the
Aectcme extiraetion shall be carried on for five hours in a Soxhlet extractor,
as improved by Dr. C. O. Weber.
Me^hwBtoMl* — The rubber insulation shall be homogeneous in char-
aetcr, shall be placed conoentrio^ly about the conductor, and shall have a
tenatle strength of not less than 800 pounds per square inch.
A sample of vulcanised rubber compound, not less than four inches in
length snail be cut from the wire, with a sharp knife held tangent to the
copper. Marks should be placed on the sample two inches apart. The
aanqile diall be stretched until the marks are six inches apart and then
imoMdiat^y released; one minute after such release, the marks shall not be
over 2| inches apart. The samples shall then be stretched until the marks
are 9 inches apart before breaking.
For the purpose of theae tests, care must be used in outtinr to obtun a
im»per sample, and the manufacturer shall not be responsible for results
drained from samples imperfectly cut.
MIgutslcal* — Each and every length of conductor shall ccnnply with
the rsquif«meDts flpven in the following table. The tests shall be made at
the Worka of the Manufacturer when tne conductor is covered with vulcan-
lubbcTt and before the application of other coverings than tape or braid.
230
PROPERTIES OP CONDUCTORS.
Tests shall be made after at least twelve hours' subiziersion in water and
while still immersed. The Toltaffe specified shall be applied for five minutes.
The insulation test shall follow the voltage test, shall be made with a battery
of not less than 100 nor more than 500 volts, and the reading shall be tskea
after one minute's electrification. Where tests for acceptance are made hj
the purchaser on his own premises, such tests shjUl be made within ten dmya
of receipt of wire of cable oy purchaser.
KnapecttOB. — The purchaser may send to the works of the mannfaetnrer
a representative, who snail be afforded all necessary facilities to make the
above specified electrical and mechanical tests, and, also, to assure himseff
that the 30% of rubber above 8|>ecified is actually put into the compouiKi,
but he shall not be privileged to inquire what ingredients are used to make
up the remaining 70% of the compound.
SO% R«bb«r C*iiB|Mand Volte^^ Tea* for ft
Fob 30 Minutes Tsbt, Takb 80% or Thbss Fioubeb.
I.
Sise.
Thickness of Insulation in Inchea.
A
A
A
A
A
A
1.000.000 to 550.000 .
4.000
6,000
8.000
10.000
11.000
0.000
500.000 to 250.000 .
4.000
6.000
8.000
0.000
8.000
4/0 to 1
Zto7
8 to 14
'8.666
4,666
5.000
4.000
6.000
7,000
10.000
12,000
13.000
II.
Sise.
1,000,000 to 550.000
500,000 to 250,000
4/0 to 1
2to7
8 to 14
Thickness of Insulatbn in Inches.
A
10.000
12,000
14,000
16,000
17.000
A
14,000
16.000
18,000
20,000
21,000
A
18.000
20 000
22,000
24.000
25.000
A
22.000
24.000
26 000
28.000
26.000
28.000
30,000
32.000
a
30.000
32.000
34.000
86000
1
DIELECTRICS.
231
Onk MxnUTS ELBCTBmCATION.
1000000 CM.
WCOOOC. M.
800000 CH.
700000 CM.
600OOOC M.
600000 CM.
4oooooaic
800000 CM.
250000 CM.
4/OStrd.
3/OStrd.
2/OStnl.
1/0 Stztl.
ISoCd
2 Solid
SSoUd
48ofid
6 Solid
6 Solid
8 Solid
0 Solid
10 Solid
12 Solid
USofid
A
A
A
A
A
• • •
200
235
270
305
340
850
376
■ • ■
390
420
• • ■
43!0
470
■ • •
455
500
.. 4
L40
480
520
.. A
kSO
490
535
.. 4
160
500
545
.. 4
190
540
590
I
»20
580
635
»00 I
»50
015
680
>30 I
m
650
715
»60 (
(20
690
750
^90 4
)55
720
790
120 (
380
760
840
610 \
no I
MX)
880
985
650 :
rso )
^
940
1050
600 \
r95 1
)05
1000
1120
750 \
570 1
)90
1110
1260
[
VX) 1 1
»30 1(
)60
1200
1340
A
210
260
290
325
365
405
450
505
540
566
580
590
650
700
760
795
830
870
920
1060
1130
1200
1370
1470
A
235
280
325
370
420
465
530
590
680
660
675
690
760
830
900
940
990
1040
1100
1240
1310
1380
1540
1640
265
315
370
420
470
526
600
680
720
750
770
790
860
950
1040
1080
1130
1180
1230
1370
1440
1510
1680
1780
A
300
360
420
480
540
600
670
750
810
840
860
880
950
1060
1160
1210
1260
1300
1350
1490
1560
1620
1790
1890
•
A huchfer crade of ixMulaiing material is another gum, gutta-percha,
vixidi 18 used in ite pure state. The use of this gum is confined almost
eatirdy to the construction of the insulated core of submarine cables.
SDeeafic gravitv. 0.0693 to 0.981.
Weight per cubic foot, 60.56 to 61.32 pounds.
Weight per cubic inch, 0.560 to 0Ui67 os.
Softens at 115* degrees F.
Becomes plastic at 120 degrees F.
Melts at »2 degrees F. ...
Oxidiaes and becomes brittle* shrinks and cracks when exposed to the air,
eq>eeially at temperatures between 70 and 90 degrees F.
Oxidatioa is hastened by exposure to light.
OzidaAum may be delayed by covering the gutta-percha insulation with a
tspe wnich has been soaked in preparedstocluiolm tar.
Where gutt»-percha is kept continually under water there is no notice-
sble detenoration, and the same applies where gutta-percha leads are cov*
end with lead tulnng.
Stretched gutta-percha, such as is used for insulating cables, will stand
s strain of 1,000 pounds per square inch before any elongation.
The breaking strain is about 3,600 pounds per square inch.
The tenacity of gutta-percha is increased by stretching it.
maalatoace er Cl«ila-P«rclla under PrMa«r«. — Tlie resistance
of guttarpereha under pressure increases according to the following formula,
when R » the resistance at the pressure of the atmosphere, and r the resis-
tSQoe aft p pounds per square inui.
r-B (1+ 0.00023 p).
{
282
PROPERTIES OF CONDUCTORS.
Let D "■ diameter in mils of over gutta-percha inBuIation.
d — diameter of cable core.
W -* weight in pounds of gutta-percha per knot.
w *>« weight in pounds of copper.
Then for SoUd Cable
D - -^/Sfiw-f 491 W.
For Stranded Cablee.
D - >/70.4w + 491 W
f-V
w
1 4- 6.97 — •
Approximate Electrcetatic Capacity of a gutta-percha cable per knot is
0.19
log D — log d
microfarads.
The ^ectroataUc capttdty of a ^tta-percha insulated cable compared with
one of the same sise msulated with India rubber is about as 120 is to 100.
)
IHTidlay Cocttcieata for CorrwctlBr <k«
aace of C^atte-Porclia at aaj- Xeaiperatare to tft** f •
K. WlNNERTZ 1907.
Degree F.
Coefficient.
Degree F.
Coefficient.
Degree F.
Coefficient.
95
0.1415
74
1.089
53
6.015
94
0.1561
73
1.187
52
6.373
93
0.1721
72
1.293
51
6.722
92
0.1898
71
1.409
50
7.057
91
0.2105
70
1.535
49
7.377
90
0.2332
69
1.672
48
7.670
89
0.2574
68
1.821
47
7.943
88
0.2836
67
1.984
46
8.178
87
0.3125
66
2.161
45
8.383
86
0.3442
65
2.353
44
8.499
85
0.3833
64
2.562
43
8.585
84
0.4304
63
2.790
42
8.637
83
0.4801
62
3.035
41
8.678
82
0.5251
61
3.302 .
40
8.719
81
0.5848
60
3.588
89
8.767
80
0.6458
59
3.896
38
8.796
79
0.7066
58
4.223
87
8.834
78
0.7707
57
4.564
86
8.880
77
0.8406
56
4.919
35
8.932
76
0.9168
55
5.282
34
8.990
75
1.0000
54
5.650
33
0.053
^
DIELECTRICS.
233
IMelectric Mve«stft of Air.
The voltage required to break down the air between two terminals de-
pends on the aha^ of the terminals, the distance between the terminals,
and the constants of the circuit in series with Uie twminals.
The following curres. published by Mr. 8. M. Kintner in the proceedings
of the American Institute of Electrical Elngineers, give the voltage re-
quired to break down air gape of various len^ha under various conditions.
^^^
"*■"
^""
■■^
^""
*-
tt
u
ift
<
III
^
-^
9
Am
s-iS
^
■^
tr'
<:
^
?^
^
^
^
^
IV
X^
^
^>—
1.
^
0
7^
"?
X^'
H"
m
A
i
r
s
— ^
/.
^
w^
HKBDLBPOIVTSI
1 j^j.E.Bi> Currv
PAHKOAPOVj
BV4
•
u
r
w
^ Jl Water SbwMUtla Q«p drculi
lux Small Oondenaer
u
.
7
• V C
BoBall OoBdamn In <tap Oreati
bitldea ndtli ^maew
IB
I
^
E
•
z
1
I
(
1
III
chei
B ^
t
4
I
s
(
Fio. 29.
With regard to the use of a spark gap for measuring high voltages, Mr.
KmUier makes the following recommendations:
For the measurement of sudden pressure variations, such as those pro-
doeed on transmission lines by lightning, switching, grounds, short cir-
^ut*, etc., where Uie use of an oscUlograph or similar device is not feasible,
^.^isrk-gap method is very useful. It is, in fact, the only method bv
vbidi any satisfactory quantitative results can be obtained under such
^OBditions.
"Wlun using a gap the writer prefers 'round nose' (hemispherical
•welded terminals); (slightly concave shield/i placed back of and coaxial with
toetmuals); the gap should be standardised over the range for which it
M to he used just prior to taking measurements, and tmder as nearly the
ne surroundings, connections, etc., as possible. This preference is based
^xi. pc>nvenience of operation and greater freedom from erratic behavior
Mthuformof gap.
The aperk gap, although apparently a very simple device, requires an
*>P«t operator to get results that are at all satisfactory.'*
ii
r
234
PROPERTIES <
OP
CONDUCTORS,
1
70
lU
^
66
y
^
^
80
56
80
a at
yj
^
Y
y
^
F
IV
^
r
.
p^
P
OUBVES OF JUMP DI8TANGBS
8hleld«d Oapa. K'NoMte'Bhlelda Placed
K'Back of Tenniaab
9 1 Nonnal Qap
O II Voltmeter B«irtane« In Oi4> Obcoit
• III Water Beilatenco •• »
• lY BmaU OoadeiiaBr t
^^^
A
B
30
fiS
9A
r
-<^
16
J
10
5
0
7
f
1
1
1
a
1
I
\
1
i
0
Oap Distances in. Inches
Fio. sa
)
Volte«« •f Micift im
W. S. Andrkws.
TnuMa Oil.
Thiokness of
Mica.
Average Puno-
turing Voltage.
Thioknenof
Mica.
Average PuDo-
turing Voltage.
.001'
8,800
.006'
6,700
.0016'
4,500
.0065'
6,030
.oor
4.600
.007'
7,290
.0026'
4,760
.0075'
7.400
.003'
5,300
.008'
7,700
.004'
5,570
.0085'
8,550
.00475*
5.950
.01'
8,900
.005'
6.050
Specillc TMeraaal Coadvctlvltj of IMelcctrlcs.
Wattb Through Inch Cubb. Teupbraturc Gbadibnt 1^ C.
^>ecific
Specific
Name of Substance.
Conduc-
Name of Substance.
Conduc-
tivity.
tivity.
Air
.0006
Vulcanised Rubber . .
.00105
Glass
.0053
Beeswax
.00093
Wood
.032
Felt
.00093
Caoutchouc
.0044
Vulcanite
.00089
Guttapercha ....
Sandy Xoam ....
.0051
Cotton Wool
.00046
.085
Sawdust
.00131
Bricks and Cement
.032
Sand
.00140
India Rubber ....
.0043
Paraffin
.00121
Sand with Air Spaces
.96
DIELECTBICS.
235
ictovs for Hlffli TMMiea
Tlie lofls of energy in a high tension tranBmiaaion line due to the bniah
(fachaige from the wires depends on the electric pressure, the siie of the
conductors and the atmospheric temperature and barometric pressure.
For any given stae of conductor a certam critical electric pressure exists for
▼hich there is a sudden rise in the curve of "loss between wires." Con-
ductors should never be used in practice so small that the operating pres-
sore is greater than this critical pressure. Mr. H. J. Ryan has deduced
the following table, giving the minimum sise of conductor which should be
used for prassures from 50,000 to 250,000 volts for a distance between con-
ductoTB of 48 inches:
Operating Pressure;
Minimum Diameter
90 per cent of Critical
Kfleetive Volts.
of Conductor in
Inches.
50.000
0.058
75,000
0.106
100.000
0.192
150.000
0.430
900.000
0.710
250.000
0.990
The equation showing the relation between the maximunx value of the
preisure wave, the atmospheric tempa«ture and barometric pressure, the
oiatance between the line conductors and the radius of the conductors
for conductors larger than No. 4 B. and S. gauge is as follows:
(
where
r
9
17.940
450 + <
X 350.000
logto (^ <r
+ .07)
t
b
critical pressure at which the sudden increase in the
brush discharge takes place,
radius of conductors in inches,
distance between conductors from center to center in
inches,
atmospheric temperature in degrees Fahrenheit.
barometrio pressure in inches of mercury.
PBOPBBTIES OP CONDUCTORS CARBTINO
ALTERNATING CURRENTS.
Bbyued bt Harou> Pkndbr, Ph.D.
Beaides the ohmio nsiBtaaoe of a wire, Um following phenomena affeol
the flow of aa alternating ourreat:
Skin effeetf a retardation of the current due to the property of alter-
nating currents apparently flowing along the outer surfaoe or Miell of the
conductor, thus not making use of the fuU area.
Inituiim eifecU, (a) teUtnducHon of the current due to its altemataona,
induoing a counter JB.ALF. in the conductor; and (&) mutual induekinee, or
the effect of other alternating current drcuita.
CapacUv e^eeto, due to the fact that all lines or oonductors act aa deo-
trioal oondenaers, which are alternately charged and diichaxged with the
fluctuation* of the £Jd.F.
The eifeeUve retUlanee of a dreoit to an alternating curmt dependi
on the shape of the circuit, the specific resiatance, permeability, onoss
section and shape of the conductor, and the frequency of the current. The
current density over the cross section of the conductor is a miniTnnin at
the cento*, increasing to a maximum at the periphery; in a solid conductor
of large cross section the current is confined almost entirely to an outer
shell or *'skin." The "Skin Effect Factor" is the number by which the re-
sistance of the circuit to a continuous current must be multiplied to give
the effective resistance to an alternating current. The following oorv^
formula and table give the "Skin Effect Factor" for a straight wire of
circular cross section, the return wire of the circuit being assumed suffi-
ciently remote to be without effect, whidi is practically the oeae in an
afirial transmission line.
Let R M Reristanoe of wire in ohms to a oontinuoiifl current.
R' — Effective resistance of wire in ohms to an alternating current.
/ "■ Cycles per second.
A "- Cross section of wire in circular mUs.
^ — Permeability of wire in O.G.S. units.
I — Temperature in "C.
a * Temperature coefficient per ^C.
C «>« Percentage conductivity of wire referred to Matthieassn's
copper standard at 0^ C.
Then R'. faction of (|!|^).
This function is a complex one, and can be represented best by the
accompanying curve; however, for
f:^>3xio».
the approximate formula ^ - lO"* / p^^ +0.28
is sufficiently accurate for all practicable purposes.
286
BSIK EVrCCT FACTOItS.
« Vactan at SO° C for ■to«li*t VTIVM I
Ctivalar CrM* •»€«•
■T.
Pndaet of Cir-
tXA.
Faotorfoi
f'lSO.
Cog^W,™
"S-
.000
ffl
loiooo'ooo
fS
ss
•9
<
• nib oorrcipoDds to B3£. Mdegnph win.
238 CONDUCTOBS.
The approxiinate formula
For Iron (E.B.B. telegraph wire), reduces to
~ - 479 X 10-«\/7I + 0 J88
for fA > 12.6 X !()• and « - 20« C.
For Copper, reduces to
^ - 96 X 10-« Vfl +0.28
for M > 300 X lO* and I - 20*» C.
For Aluminum^ reduces to
^' - 76X IO-VM+0.28
for M > 500 X 10* and < » 20*' C.
ExampleB: To find the effective reeiatance of a round-wire .£ inch in
diameter, permeability 500, oonduotivity 10 per cent, at 15 eydee per
second and 0° C:
|^.15X500X10X.26X10>_^^^^^
R'
From the ounre -^^ — 1.63
or effective resistance R' •-> 1.63 R,
To find the effective resistance of the same wire at 60 cycles per second:
UCA
l+ai
7.5 X 10-w
therefore, from formula ^ ^ 2.73 + 0.28 - 8.01
or effective resistance R* » 3.01 R.
AKIil* IlfOITCTCOlV Alfl» IlfDUCmrC lUBACTAHCK
Of TSAHftninMioir cmucvixs foiuubi*
BIT VAMMMJLMMa WUKKS.
The CoeMcient of Self Indudion (L) of an elementarv circuit is defined as
the ratio of the number of lines of induction produced by a current flowing
in the circuit divided by the current in the circuit. When the conductor has
a finite cross section the exact definition of the coefficient of self induction
is the ratio of twice the energy of the magnetic field produced by the cur-
rent flowing to the square of the current.
The practical unit of self induction is the henry; sometimes the milli-
henry is used, which is equal to tiAtv of a henry.
The coefficient of self induction of a circuit depends on the sise and
shape of the circuit, the cross section and shape of the conductor, the per-
meabilities of the conductor and the surrotrnding medium, also, when the
skin effect is large, upon the frequency of the current and the specific re-
sistance of the conductor. The instantaneous E.H.F. induced in a cir-
cuit by any change of the current flowing in the drouit is e ■» — -j; {Li), or,
at
if L is constant, which is strictly true when there is no iron in the circuit,
and approximately so in any case, « -" ^ ^ j^ *
When a constant RM.F. is impressed on a cirouit or coil coDtainiii|S
iDdtfoJiMloe, the current does not reach its full value instantly, as it »
8SLF INDUCTIOK AJfD DTDUCTITS BEACTAKCS. 239
oppand at first by a oountar-eleetroiDotive force due to the induotanee.
TiaB eoonter-eleetroiiiotive force gradually grows less until the current
tttchfls its full strength, which theoretically takes an infinite time, and in
^etiee it is usual to determine the time taken for the current to attain
63^ of its full value and this period is called the time<on$ianU
'nine«>nstant in seconds -■ -;: ^rT
ohms resistance
henrys X final amperes
applied volts
If the impressed E.M.F. varies according to the sine law and L is con-
Btant, the aective value of the counter inductive E.M.F. is
viwre / — cydes per second or frequency and / — the effective value of
the nvTcat. 2 wfL is called the inductive reactance or simply the inductance
of the eiremt.
Ihe induced ELM.F. lags 90° behind the current. The E.M.F. required
to onreome the induced £LM.F. leads the current by 00°.
rmwmmim for BwiifMmAwugtimm a«d M«d«ctlve
I^ r — radius of wire in inches.
n -■ number of wire on B. and S. gauge.*
D ■■ distance between wires in inches. ^^
I ■■ distance of tranomission O^^g^^ o' one wire) in 1000 feet.
L - eoefllcient of self induction of 1000 feet of wire in millihenrys.
~ frequency of current in cycles per second. ....
- 2 «/L X 10^ — inductive reactance of 1000 feet of wire m ohms.
i
Bnreu-vBASB Cncnir — 2 Wibi
iQ_-^-— 9 (
Fu. 2«
Total self induction of circuit — 2 2L.
Total inductive reactance of circuit * 2 IX,
THln-PBASB ClBCITXT 8 WfRBB.
Fi«. 3*
Total aelf induoUon per phase (circuit formed by any two wires) ^y/ZW.
Total inductive reactance per phase — V^S IX,
L - 0J01524 + 0.14 logio (^
-0.00705n+A.
where i4 - 0.14 logic + 0.1258.
* Bee table on next page for values of n for wires larger than Ko. 0.
^
r
240
CONDUGTOBS.
Jfor UiOir
L - 0.01624 y. + 0.14 log^o (^
where ^ — permeability of the iron, m varies with the qoality of the inm
and also with the strength of the onrrent. The above formiila is '
only in case ^ is constant over the cross section of the wire, which in any
Eractical case is only approximately true. The tables on p. 248 are calen-
ited for |A — 160, corresponding to good quality telegraph wire, and.
therefore,
X -2.386 +0.14 logto-'
F
D.
ii.
^
1 in.
.0662
.0687
.1083
.1268
■k
2
.1679
n
3
.1925
li
0
.2347
w
12
.2768
V
18
.3016
24
.3190
36
.3436
48
.3611
60
.3747
\
72
.3867
}
V»liiea of n for IVlrca Iia
^iV^r tluuft IVo. O, II. ai
sd A.
Sise.
n.
«
00 B. and S.
-1
000
-2
0000
-3
260,000 C. M.
-3.743
800.000
-4.636
860.000
-6.203
400,000
-6.783
460.000
-6.206
600,000
-6.762
660.000
-7.166
600,000
-7.644
060,000
-7.891
700,000
-8.212
•
760.000
-8.612
800,000
-8.792
860,000
-9.066
900.000
-9.302
060,000
-9.637
1.000.000
-9.760
L ^
k.
8BLF INDUCTION.
241
^
•M Hk MilltfcwiTy pmr 1
Nora. — The self izuiuetion of ft stranded wire is alichtly less than that
of a aolid wire of the same cross section, and slightly greater than
that of a soiid wire having the same diameter, but more nearly equal to
tbat of a solid wire with equal cross section. . The exact value of the self
induetaon of a steand is a complex expression involving both the sise and
number of the individual wires. (See UEetairaqe Blectrique, Vol. Ill, p.
20.) For aD practical purposes the self induction of a strand may be
taon oqoftl to that of a solid oonductw having the flaose oroee eeetion.
L-m .00705 n + ii.
B.aad8.
0000
000
00
0
1
a
4
6
6
8
10
U
14
Interaxial Distances.
r
V
!6977
.1117
.1013
.1180
.1084
.1269
.1225
.1401
.1367
.1541
.1507
.1682
.1647
.1822
.0871
.0043
.1012
.1083
.1154
.1223
.1364
.1436
.1506
.1647
.1788
.1928
.2068
1'
.1046
.1116
.1187
.1258
.1329
.1398
.1539
.1610
.1681
.1822
.1963
.2103
.2243
2*
8'
.1467
.1714
.1538
.1778
.1608
.1855
.1670
.1926
.1750
.1946
.1830
.2066
.1961
.2207
.2032
.2278
.2102
.2349
.2243
.2490
.2384
.2631
.2525
.2772
.2665
.2911
Interaxial Distances.
Or. Mils and
B.and&
Gn«e.
6»
12*
18*
24'
36'
48'
60'
72*
UOOXXX)
.1659
.2080
.2327
.2502
.2748
.2923
.3059
.3169
900.000
.1691
.2112
.2359
.2534
.2780
.2055
.3091
.3201
800000
.1727
.2148
.2395
.2570
.2816
.2991
.3127
.3237
700000
.1768
.2189
.2436
.2611
.2857
.3032
.3168
.3278
000.000
.1815
.2236
.2483
.2658
.2904
.3079
.3215
.3325
500000
.1871
.2292
.2539
.2714
.2060
.3135
.3271
.3381
iBOJOCO
.1903
.2324
.2571
.2746
.2092
.3167
.3303
.3413
J0O.OOO
.1939
.2360
.2807
.2782
.3028
.3203
.3339
.3449
850,000
.1980
.2401
.2648
2823
.3069
.3244
.3380
.3490
800.000
.2027
.2448
.2095
.2870
.3116
.3291
.3427
.3537
250.000
.2083
.2504
.2751
.2928
.3172
.8347
.3483
.3593
0000
.2135
.2666
.2803
.2978
.3224
.3399
.3535
.3645
000
.2206
.2627
.2874
.3049
.3295
.3470
.3606
.3716
00
.2276
.2648
.2945
.3120
.3366
.3541
.3677
.3787
0
.2347
.2768
.3015
.3190
.3436
.3611
.3747
.3857
1
.2418
.2839
.3086
.3261
.3507
.3682
.3818
.3928
2
•248«
.2009
.3156
.3331
.3577
.3762
.3888
.3998
4
.26291
.3050
.8297
.3472
.3718
.3893
.4029
.4139
6
.2770
.8191
.3438
.3613
.3859
.4034
.4170
.4280
8
.2011
.3832
.8579
.3754
.4000
.4175
.4311
.4421
10
.305^
.8478
.3720
.3895
.4141
.4316
.4452
.4562
(
r
242
C0NDUCTOE8.
ReactMuse Im OIimm P»r lOOO feet •T fl^lM ]V«m-
Mapnetlc IFire.
100 Ctcles pbb Sbcomd. X >« 0.6283 L,
NoTB. — Inductive reactance at other frequencies proportional to ▼aluet
given in this table.
B. and 8.
Gauge.
Interaxial Distances.
r
r
r
1'
2*
3-
0000
000
00
0
1
2
4
5
6
8
10
12
14
.0636
.0681
.0770
.0858
.0946
.1034
ioeis
.0702
.0747
.0791
.0879
.0968
.1056
.1144
.0547
.0592
.0635
.0680
.0725
.0768
.0857
.0902
.0946
.1034
.1123
.1211
.1299
.0657
.0701
.0745
.0790
.0834
.0878
.0966
.1011
.1056
.1144
.1233
.1321
.1409
.0922
.0966
.1010
.1055
.1099
.1143
.1231
.1276
.1320
.1409
.1497
.1586
.1674
.1076
.1116
.1165
.1209
.1254
.1298
.1386
.1431
.1475
.1564
.1652
.1741
.1828
I
Cir. Mils and
Interaxial Distances.
B. and 8.
Gauge.
6'
12*
18'
24*
36'
48*
60*
72*
1.000,000
.1042
.1307
.1462
.1572
.1727
.1837
.1922
.1901
900.000
.1062
.1327
.1481
.1592
.1747
.1857
.1942
.2011
800 000
.1085
.1350
.1505
.1615
.1769
.1879
.1965
.2034
700,000
.1111
.1376
.1531
.1640
.1795
.1905
.1990
.2060
600,000
.1140
.1405
.1560
.1670
.1825
.1954
.2020
.2089
500,000
.1176
.1440
.1595
.1706
.1860
.1970
.2065
.2124
450.000
.1196
.1460
.1615
.1725
.1880
.1990
.2076
.2144
400,000
.1218
.1483
.1638
.1748
.1902
.2012
.2098
.2167
350.000
.1244
.1509
.1664
.1774
.1928
.2038
.2124
.2193
300,000
.1274
.1538
.1693
.1803
.1958
.2068
.2168
.2222
250,000
.1309
.1573
.1728
.1838
.1993
.2103
.2188
.2257
0000
.1341
.1606
.1761
.1871
.2026
.2136
.2221
.2290
000
.1386
.1651
.1806
.1916
.2070
.2180
.2266
.2335
00
.1430
.1695
.1850
.1960
.2115
.2226
.2310
.2379
0
.1475
.1739
.1894
.2004
.2159
.2269
.2364
.2423
1
.1519
.1784
.1939
.2049
.2203
.2313
.2399
.2468
2
.1563
.1828
.1983
.2093
.2247
.2357
.2443
.2512
4
.1652
.1916
.2072
.2181
.2336
.2446
.2531
.2601
6
.1740
.2005
.2160
.2270
.2425
.2535
.2620
.2689
8
.1829
.2093
.2249
.2359
.2513
.2623
.2709
.2778
10
.1918
.2182
.2337
.2447 .2602
.2712
.2797
.2866
^
INDUCTITE BEACTAKCS.
243
InOlmui 99W%OOmWm$ •fS^lMiroi
25CTGiiS8 Per SBCOZfD. X - .1571 L.
IntaraxiA] Distaaces.
B-andS.
Gaoge.
V
y
f
1*
TT
3'
0000
.0137
.0148
.0160
.0175
.0230
.0242
.0209
000
.0279
00
.0159
.0186
.0253
.0291
0
.0170
.0181
.0108
.0209
.0264
.0276
.0302
1
■ ■ • a
.0313
2
.0153
.0192
.0220
.0286
.0325
4
.0176
.0214
.0242
.0308
.0347
5
•oiio
0187
.0225
.0253
.0319
.0358
6
.0170
0108
.0236
.0264
.0830
.0360
8
.0192
0220
.0259
.0286
.0852
.0391
10
.0215
0242
.0281
.0306
.0374
.0413
12
.0237
0264
.0308
.0330
.0396
.0435
14
.0250
0286
.0325
.0352
.0418
.0457
(Tir. Mibaiid
B.aad8.
Gauge.
Interaxial Distanoefi.
1,000,000
MXMXX)
800000
TOOiOOO
eoaooo
soaooo
4B0M0
400.000
mooo
aootooo
250000
0000
000
00
0
1
2
4
6
8
10
6'
12*
18'
24'
36'
48'
60*
72*
.0261
.0327
.0366
.0393
.0432
.0460
.0481
.0498
.0286
.0332
.0371
.0398
.0437
.0465
.0486
.0603
.0272
.0338
.0377
.0404
.0443
.0471
.0492
.0609
.0278
.0344
.0383
.0410
.0449
.0477
.0498
.0616
.0285
.0351
.0390
.0417
.0456
.0484
.0505
.0622
.0294
.0360
.0399
.0426
.0465
.0493
.0514
.0631
.0209
.0365
.0404
.0431
.0470
.0498
.0619
.0536
.0306
.0371
.0410
.0437
.0476
.0603
.0626
.0542
.0811
.0377
.0416
.0444
.0482
.0510
.0631
.0548
.0319
.0385
.0423
0451
.0490
.0517
,0538
.0656
.0327
.0393
.0432
.0460
.0498
.0526
.0647
.0564
.03S5
.0402
.0440
.0468
.0506
.0534
.0656
.0673
.0347
.0413
.0452
.0479
.0518
.0646
.0667
.0684
.0358
.0424
.0463
.0490
.0529
.0566
.0578
.0596
.0369
.0435
.0474
.0501
.0540
.0667
.0589
.0606
.0380
.0446
.0485
.0512
.0551
.0678
.0600
.0617
.0391
.0457
.0496
.0523
.0562
.0689
.0611
.0628
.0413
.0479
.0518
.0545
.0584
.0612
.0633
.0650
.0435
.0501
.0540
.0568
.0606
.0634
.0655
.0672
.0457
.0523
.0562
.0500
.0628
.0656
.0677
.0696
.0480
.0540
.0684
.0612
.0661
.0678
.0699
.0717
(
COITDTJ0TOB8.
M CrcLn Pbr Sboohd. X — 0.3770 L.
loMnxia] DiMuioaB.
Or, WlaMid
350.000
300,000
InMnxUI DiaUoMa.
a-
w
w
48*
60*
72*
.67
^
INDUCTIVB BEACTANOB.
245
of Xoop Vonsetf bj Two
hoao XvuMMiliMion m<lii«>.
of
Ormb pkr 1000 Fbbt or Lnni* (Cokdvctor Non-Maonbtio )
100 Ctclks per Skcond.
■^loop — ' -^for angle wire.
Nor. — Inductiire reaotanoe at other frequenoies proportional to ralaes
$wa in thiB table.
1
il.ani1.S
Ga««e
1'
V
r
1'
2'
3'
0000
.0047
.1138
.1596
.1864
000
.1025
.1214
.1673
.1933
00
.1100
.1291
.1749
.2018
0
.1178
.1368
.1827
.2094
1
.1255
.1445
.1903
.2171
2
.1062
.1331
.1521
.1980
.2248
4
.1215
.1484
.1674
.2133
.2401
5
.1102
.1293
.1563
.1758
.2210
.2478
«
.1179
.1369
.1638
.1828
.2286
.2554
8
.1333
.1523
.1791
.1982
.2440
.2708
10
.1487
.1677
.1945
.2135
.2503
.2862
12
.1630
.1830
.2097
.2288
.2746
.3014
U
.1791
.1982
.2250
.2440
.2898
.3167
Or.lCibaad
InteraxiBl Distances.
B.iDd8.
Gm«b.
6'
12"
18»
24'
36'
48*
60*
72*
IJOOO.000
.1807
.2285
.2538
.2724
.2992
.3183
.3330
.8450
900,000
.1842
.2300
.2568
.2759
.3027
.3218
.3365
• o4oO
9QO.O0O
.1881
.2339
.2807
.2798
.3066
.3267
.3404
.3524
700.000
.1928
.2384
.2652
.2843
.3111
.3302
.3449
.3569
600.000
.1977
.2435
.2703
.2894
.3162
.3353
.3500
.3620
6004X)0
.2038
.2496
.2764
.2955
.3223
.3414
.3561
.3681
4604)00
.2073
.2530
.2799
.2989
.3258
.3449
.3596
.3716
jOWOO
.2111
.2570
.2889
.3029
.3296
.3437
.3636
.3755
S60.000
.2156
.2615
.2884
.3074
.3341
.3532
.3681
.3800
3004)00
.2208
.2865
.2984
.3125
.3393
.3584
.3731
.3851
250000
.2268
.2726
.2995
.3185
.3454
.3644
.8702
.3911
oooo
.2324
.2783
.3052
.3242
.3511
.3702
.8849
.3069
000
.2402
.2861
.8180
.3320
.3587
.3778
.3927
.4047
00
.2478
.2937
.3206
.3397
.3665
.3856
.4003
.4123
0
.2556
.3014
.8282
.3473
.3742
.3932
.4079
.4199
1
.2632
.3092
.3360
.3551
.3818
.4008
.4157
.4277
2
.2709
.8168
.3437
.8627
.3894
.4085
.4234
.4353
4
.2863
.3820
.8591
.3780
.4048
.42LD
.4386
.4508
6
.3015
.8475
.3743
.3934
.4203
.4303
.4540
.4660
8
.8170
.8627
.8898
.4088
.4355
.4546
.4695
.4814
10
.3324
.8781
.4060
.4241
.4509
.4700
.4847
.4967
{
^ Uncth o( line equals one half the total length of wire in the loop.
CONDOCTOBS.
;rioap - v/3 X for eioelt
»
Im™=^ Db.«z.«.
Gauge.
i-
i'
I*
1'
2'
3'
0237
028S
039D
*02B5
ra«
14
0563
Cir. Mi
,r.
GBuge.
I.-
24'
»-
48*
60"
72-
1.000
1
' i
1
1
WO
1
2
10
;E
:0721
:o7a;
fl
Q70C
11
07fi7
E
si
ORSR
1
Q7S7
E
nsa;
1
093;
loi;
S
085;
0871
0S8.'
OSll
1
i
ii
08W
0909
if
oat
1
OM3
0039
DOSS
0978
0093
IIW
lias
li hall the total Imgth of wire in the knp.
INDUCTIVB
0 FmBT or Iohc* (Cohdoctob Nox-ll^aHi
Zknp — Va Jl (or HDcls wire.
InUnzuJ Kstuion.
B.ud&
Gn*..
1*
r
*-
i-
2-
3*
(UOO
0508
0«S3
OOSB
1118
on
06UJ
0728
1004
1190
oo
OSOO
0774
1049
121L
M3f
i
E
ii
1303
vn«
0B38
0821
0983
1372
1533
0»i4
075
1164
1625
1
08B2
0083
loss
268
1373
1M8
14
107S
1180 1
3fi0
14M 1
1739
1900
CSr. Kilt and
B.uda.
(i»W>.
-
UPOO0W
000
00
10
i
* Uofth nf line equals one half the Ui
J leOBth ot wire in the loop.
248
COKBUCTOBS.
•elf HnducMmi
IM ]HUlllb«av7« ptBT 1«90 Feet •f
I, -2.286 +.14 logic (f)-
1
Roeblioc
Dia.
In.
•
Gauge.
t
.225
1'
2*
3*
6'
9'
12*
18'
24'
4
2.4189
2.4610
2.4857
2.5278
2.6526
2.6699
2.5946
2.6121
6
.192
2.4285
2.4706
2.4953
2.5374
2.5621
2.5796
2.6042,2.6217
8
.162
2.4389
2.4809
2.5056
2.6478
2.5724
2.5899
2.6146
2.6321
9
.178
2.4443
2.4865
2.5111
2.5533
2.5779
2.5964
2.6201
2.6376
10
.135
2.4499
2.4921
2.5167
2.5589
2.6835
2.6010
2.6257
2.6432
11
.120
2.4571
2.4992
2.5239
2.5660
2.6907
2.6082
2.6328
2.6503
12
.105
2.4652
2.5074
2.5319
2.6742
2.6988
2.6163
2.6409
2.6584
14
.080
2.4817
2.5239
2.5485
2.5907
2.6163
2.6328 2.6576
2.6748
JbudnctiTe lieactence to Olinu per 100# F«e4 of ftolid
Iron lirire.
100 Ctcleb Per Second. X — 0.6283 L.
Note. — Inductive reactance at other frequencies prop(Mttonal to
values given in this table.
Roebling
Dia.
In.
.225
.192
.162
.148
.135
.120
.105
.080
Interaxial Distances.
Gauge.
1'
2*
3*
6'
9*
12*
18'
24*
4
6
8
9
10
11
12
14
1.5191
1.6251
1.5316
1.5350
1 .6386
1.5431
1.5482
1.5585
1.5455
1.5516
1.5581
1.5615
1.5650
1.5695
1.6746
1.6850
1.6610
1 .5671
1.5735
1.5769
1.5806
1.5850
1.5901
1.6005
1.5875
1.6936
1.6000
1.6035
1.6069
1.6116
1.6166
1.6269
1.6029
1.6090
1.6165
1.6189
1.6226
1.6269
1.6320
1.6424
1.6139
1.6199
1.6266
1.6299
1.6335
1.6379
1.6430
1.6684
1.6294
1.6356
1.6419
1.6464
1.6489
1.6634
1.6585
1.6689
1.6404
1.6466
1.6529
1.6664
1.6590
1.6644
1.6605
1.6700
CAiPAcnnPY. c Ar Acnnr »» actawcjbl j^to ch[a»€»-
rara cumtsif t of ntAivsmssxoM cmcuixs
9'OlUIIEIi mr PARAIiIiBIi ^imsA.
Whenever a difference of potential is established between two or more
conductors a static charge manifests itself on each conductor. If there
are but two conductors present these static charges are equal and oppMite.
Two conductors thus carrying equal and opposite charges are said to foiiBi
a condenser. The ratio of the otiarge {q) on one of the conductors to the
difference of potential (e) between the two conductors is called the capa*
city (C) of the condenser, %,e„
If Q is expressed in coulombs and e in volts, the unit of capacity as de-
fined oy this eqiiation is called the farad. A capacity as large as a farad
^
TBAN8MI8SI0N CIRCUITS. 249
li ft ntftthamatieal fietion ; the mit wi^lojred in praotioe is the microfarad,
'which u one millionth of a farad.
Tike capacity of a condenser depends on the sise and shape of the con-
doctora, the specific inductive capadty of the surrounding medium, and
its distanoe from other conductors.
Tba iofltantaneouB capacity E.M.F. is in practical units.
and ths effective value of this E.M.F. for a sine wave current is
10«
S^
2irfC
10*
The cqveaaion .^ is called the capacUy reactance, or simply the cap€U!v-
iBaee, of the circuit. The reciprocal of this quantity, namely, -r^. ib
csOed the capacity 9U»ceptancef this is the quantity used in the treat-
. smt of the capacity of transmission circuits.
The earrent required to charge and discharge a condenser is called
ths danfing eurrerUi for a sine wave of imprened E.M.F. the chatging
cmtntii
7,-2 *fCB X 10-«.
TIm oapadty E.M.F. leads the current by 90^; the E.M.F. required to
ovveoDM the eapactiy E.M.F. lags 90** behind the current.
Naglv-PlMiM Tirmaemisetom Mila«. — The capcuuty effect in a sin^le-
; Plksie transmisrion line is the same as would be produced by shuntmg
; aenai the line at each point an infinitesimal condenser having a capacity
:*Visl to that of an infinitesimal length of circuit. The
I {net ealculation of this effect involves the use of hyperbolic t I
I nnetions and oonmleac algebraic quantities. A close approz- _ _
I matMB is to oonsioer a condenser of half the capacity of the >-''~| |~^
I iM ihimtsd across the line at each end. A still closer ap- I
P^ramatton is to divide the fine into three equal parts and '
2J«i«r the capacity of each section concentrated m a con- Fio. 4.
I ^"■■^ •.* the center of that section, but in most practical
f M> this refinement is not necessary. For the purpose of calculating the
I r^'IVJiK current tL very simple and in general sufficiently accurate method
I i'S.^fS^P* the current taken by a condenser having a capacity equal
wwat of the entire line when ehaiged to the pressure on the line at the
g«Mwg end. For the calculation of the effect of capacity on the effi-
^S~ wgahition of transmission lines see page 264.
araree-PliaAe TnMntiaeiMt Xitee. — The capadty effect in a three-
phase transmisrion line is the same as would
he produced bv shuntini? the line at each point by
tiiree infinitesimal condensers connected in star
^th the neutral point grounded, the capacity
of each condenser being equal to twice that of
a condenser of infinitesimal length formed by any
j^ two of the wires. The effect of capacity on the
JSr^/jt p«uIation and efficiency of the line can be deter-
^'^^ '^V^ mined with sufficient accuracy in most cases by
Of ^Si^rj eoDsidenng the Kne shunted at eaeh end by three
«_^ _ oondensers connected in star, the capacity of each
"O. D. condenser being equal to that formed by any two
A. -.«.—_« A . T''** *" *•** '™«- OSee page 264.)
■M*wro™»te value for the charging current per wire is the current
jgwwi to charge a condenser, equal in capacity to that of any two of the
mSTllS Jr* P«""»® •.* ^^^ generating end of the line between any one
*"• and the neotral pmnt.
{
250
CONDUCTORS.
Formuls:
Let
r « radius of wire in inches,
n » number of wire on B. and S. gauge.^
H ■" height of wires above ground.
D ■• distance between wires in inches.
I >■ distance of transmission Oength of one wire) ia 1000 f
V ■■ impressed voltage between adjacent wires at generating
Fo"" impressed volts between any wire and ground or n<
at generating end.
Co"* capacity per 1000 feet of a single wire parallel to the
in microfarads.
C — capacity per 1000 feet of circuit (2000 feet of wire) f<
by two paralld wires.
/ — frequency of impressed E.M.F. in cycles per second.
2 wiC
(iD -" ~TqF "" capacity susoeptance per 1000 feet of a single
parallel to the earth.
h "" -775- "■ capacity susceptanoe per 1000 feet of circuit (2
feet of wire) formed by two parallel wires.
K * dielectric constant of surrounding medium. For bare
insulated overhead wires, without metallic sheath, K ■■
Sinrle Overficiad Wire with Bartk lt««iai
I
Co-
.007354
logio
2H
Total capadty of circuit ^ IC,
Total capacity susceptance of circuit ■■ { 6.
mi^/A^M.yMm^'jA,My//M ^otal charging current - X hV^
Fig. 6.
Vwo Overhead ITi
, SlB^le-Pliiiae.
C -
.003677
k-2^--H
1
B + 13.7n
Total capacity of circuit — Z C Fia. 7.
Total capacity susceptance of drcuit— { b.
Total charging current •» 2 b F.
Two irirea In Oronnded MeUilllc Alieatli, AiBrl«-P^
.003677 K
FiQ. 8.
, \2a R^ - an
^"^'^ L'V «H^J
Total capacity of circuit — Z C,
Total capacity susceptance of circuit
Total cliarging current ^ lb V.
- lb.
• For values of n for wires larger than No. 0 see page 240. ^
t B - 272 logiQ D - 215. For values of B see p. 251. For stranded wira
neither formula is strictly accurate: the logarithmic formula gives reaulti
practically correct; values calculated by the second formula are about 3 pe
cent too small.
TBAN8MISSION CIRCUITS.
251
CmMeatrtc Cable la «r«aad««l Metallic Slieatb,
JU*. C* «» oapaeity in microfarada per 1000 feet of oondeoMr fonned by
the two eonductors.
<y»- capacity in microfarads per
1000 feet of oondeosa' formed by
outer ooinduetor and sheath.
Then C ' - ^5QI3S1^«
^„ _ .00735Jjgt
Total chaiKins crirrent =- / 6' F + / 6" Fo.
Three Overliead irire», Tliree-Pliaae.
.003677
Fig. 0.
q::?^
c-
logio
D
r
1
O
Fio. 10.
B + 13.7 n
Total capacity per wire — 2 Z C.
Total capacitance per wire — 22b.
Total cbaiiging current per wire *= — -=- — 2 Z 6Fo.
V3
la Metallic Slieatb, Tliree-Pliaae.
.007364 if
[3 a» (ft«j-a»)n
To«al capacity per wire — 2 Z C.
Total capacitaiuse per wire «> 2 Z b.
t ^_^
• B - 272 lo^jo r> - 216. For vahiee see table. For stranded wirce
n«j«r formula is strictly accurate; the logarithmic formula gives results
J««i«ally correct; values calculated by the second formula are about 3
<Kos too small.
per
PROPBBTIBS OP CONDUCTORS CARRYING
ALTERNATING CURRENTS.
Rbtubd bt Harold Pbndsb, PhJ).
BendM the ohmio resiatonoe of a wixe, the foUowing phenomena a£Feet
the flow of an altematinf current:
Shin effeotf a retardation of the current due to the property of altera
nating currents apparently flowizu alone the outer Burface or ahell of the
conductor, thue not making use ofthe fuU area.
Inductive effeeU, (a) teUinduction of the current due to its altonationfl,
inducing a counter £.M.F. in the conductor; and (6) mntual induckinet^ or
the effect of other alternating current drcuite.
Capacity effeetB, due to the fact that all lines or conductors act as elee-
trical condensers, which are alternately charged and dischaxged with the
fluctuations of the KM.F,
Tlie effeetiM retirtanee of a circuit to an alternating currant depends
on the shape of the circuit, the specific resistance, permeabihty. enm
section and shape of the conductor, and the frequency of the current. Tne
current density over the cross section of the conductor is a minimum at
the center, increasing to a maximum at the periphery; in a solid ocmductor
of large cross section the current is confined almost entirely to an outer
shell or "skm." The *'Skin Effect Factor" is the number by wUdi the re-
sistance of the circuit to a continuous current must be multiplied to give
the effective resistance to an alternating current. The following curv^
formula and table give the "Skin Effect Factor" for a straight wire of
circular cross section, the return wire of the drcuit being assumed suffi-
ciently remote to be without effect, which is practically the case in an
a&ial transmission line.
Let R mm Resistance of wire In ohms to a continuous eurrsnt.
R* >« Effective resistance of wire in ohms to an alternating current.
/ >« Cycles per second.
A ■" C^ces section of wire in circular mils,
fi — Permeability of wire in O.G.S. units.
< — Temperature in ®C.
a -■ Temperature coeffident per ^G.
C ■■ Percentage conductivity of wire referred to Biatthi assent
copper standard at 0" 0.
Then B'.toetionof (|!|^,).
This function is a complex one, and can be represmted best by the
accompanying curve; however, for
{^>3X10W.
R* I fp^CA
the approximate formula -^ — 10~*y Yt:^"+0.28
is sufficiently accurate for all practicable purposes.
286
SKIN SrFBCI FACTORS.
mtm ■«*•« rmetmtm m* MK O. tmr MnUfM W^lM* Ba*iar
Pioduotofar- p,^
ar*lbT
ProduetofCii-
rMtorfor
tXA. '
■uo.
Cydi^J*^ Co^
'00 "
■>Ji'
— Sooiooo
fi,000.000 1
■ooo~
.000
i.ooa.000
10,000,000 1
.000
2,000.000
0«8
20,000,000 1
.000
s.000.000
IM
ao.000.000 1
4MO.00O
40.000.COO 1
UODOOO
333
50.000,000 1
ftOOO.000
70,000,000 1
12«
80
»o,ooo
158
!ow
M
IBS
.OSS
785
vo.tm
.104
974
IM
XX),000
ISO
iTjsooiooo
:2eo
a».ooo.ooo
42
200
.330
26.000.000
B8
260
790
.46e
30.ODO.aOO
30C
037
.570
.680
31
40C
20
.737
4M)00.000
40
4SC
000,000
31
sajmjooa
XJO.OOO
!oe5
S6M0m
S3
oooioSo a
-06
»
600
6S
.18
i
' Thk corrMpondi to E.B.B. Mesnph wire.
TRANSMISSION CIRCUITS.
267
mf
C«
per IV^lrtt per lOOO
M< Im Am
drcnn
■ BXTWKSN WiRss, E" 10,000 VoLTB. Frbqubnct, / — 26 CrcLBS
PBR SSCOND.
Ca^BOINa CUBBJBNT PBB WtBB — 1.815 C.
NoTK. — Values of chars^ing current at other pressures are proportional
to those given in this table.
Interazial Distances.
Dia.
over
Insai.
I'
01358
.01312
.01263
.01214
.01167
.01230
.01138
.01001
.01045
.01073
.00082
,00006
.00833
.01083
.01002
.00800
.00768
.00690
.00624
.01132
.00967
.00900
.00844
.00748
.00671
.00610
.00559
Y
.01299
.01183
.01085
.01004
.00933
.00871
.00769
.00728
.00690
.00624
.00670
.00523
.00486
1'
.01044
.00069
.00902
.00844
.00793
.00740
.00673
.00641
.00610
.00559
.00515
.00479
.00446
.00710
.00673
.00641
.00612
.00584
.00559
.00515
.00497
.00479
.00446
.00417
.00394
.00372
8'
.00597
.00572
.00548
.00526
.00606
.00488
.00454
.00430
.00425
.00309
.00876
.00856
.00337
6'
.00470
.00454
.00439
.00425
.00412
.00399
.00377
.00367
.00856
.00337
.00821
.00307
.00294
12*
.00388]
.00377
.00367
.00367
.00347
.00337
.00321
.00314
.00307
.00294
.00281
.00260
.00259
18'
.00852
.00843
.00834
.00327
.00318
.00310
.00296
.00290
.00283
.00272
.00261
.00252
.00243
Sue Cir. Mils
Interaxial Distances.
Stranded.
6'
12*
18'
24'
36'
48'
60*
72*
14)00.000
000,000
SOO.OOU
750000
7O04X)O
eooxxK)
fioaooo
450.000
4oaooo
350.000
300.000
260.000
0000
000
00
0
1
3
4 .
Solid 0
Solid 8
Solid 10
.00055
.00641
.00626
.00617
.00608
.00590
.00570
.00559
.00548
.00535
.00521
.00504
.00492
.00474
.00457
.00443
.00426
.00412
.00388
.00356
.00337
.00321
.00506
.00497
.00488
.00483
.00506
.00466
.00454
.00446
.00439
.00430
.00421
.00410
.00403
.00390
.00379
.00368
.00357
.00348
.00330
.00307
.00^4
.002dl
.00446
.00439
.00432
.00428
.00423
.00416
.00405
.00399
.00392
.00386
.00379
.00376
.00363
.00354
.00345
.00336
.00327
.00318
.00303
.00283
.00272
.00261
.00412
.00405
.00399
.00396
.00392
.00385
.00376
.00372
.00367
.00361
.00354
.00347
.00341
.00332
.00323
.00316
.00308
.00299
.00287
.00269
.00259
.00249
.00370
.00367
.00361
.00859
.00856
.00350
.00343
.00337
.00334
.00328
.00323
.00318
.00312
.00305
.00298
.00292
.00285
.00278
.00267
.00252
.00241
.00234
.00847
.00343
.00337
.00336
.00334
.00328
.00321
.00318
.00314
.00310
.00305
.00299
.00296
.00288
.00283
.00276
.00270
.00265
.00254
^239
.00232
.00223
.00330
.00827
.00323
.00321
.00318
.00312
.00307
.00805
.00301
.00296
.00292
.00287
.00283
.00278
.00270
.00267
.00259
.00254
.00245
.00232
.00225
.00218
.00318
.00314
.00310
.00308
.00307
.00301
.00296
.00294
.00290
.00287
.00283
.00278
.00274
.00289
.00263
.00258
.00252
.00247
.00238
.00227
.00218
.00212
ALTEBKATINO CURBBNT CIRCUITS.
259
ja,e tntp^nee («) of a circuit is defined aa the ratio of the difference in
preasure (^ective) between the two ends of the conductor to the current
^*%Sp'*I?},™^°8 through the conductor. ,
The £.M.F. required to overcome impedance is
In the case of direct currents « — r.
The following are typical altonating current circuits:
B *■ resistance in ohms.
Z -• impedance.
• — 2 ir/.
L — coefficient of sdf induction.
C ■» capacity.
or diacrminmaitieaUy,
and I»dactaMC«, In
(
Fio. 12.
and Capadtar li
Fxa. 13.
Jic«, XndnctoBC*, and Capacitj li
or di^fti ammatically,
Nors-T-Intiunsausaion hnes the capacity is m parallel with the reaist-
anee and mductance; the above formula mvolving capacity do not there-
fore apply. For the discussion of capacity of transmission lines see p 264.
260 CONDUCTORS.
THE DIMENSIONS OP CONDUCTORS FOB
DISTRIBUTION SYSTEMS.
Bt Harold Pendeb. Ph.D.
To proportion properly the sise of the conductors for a distributioo
■ystem. the following data with res&rd to each circuit ia necessary:
1. The nM»-yimiim power to be transmitted, or the maTimiiTn load on the
line.
2. The load factor, or the variation of the power delivwed with tima.
8. The length of the line.
4. The distribution of the load alon^^ the line.
5. The pressure at which the power is to be transmitted.
6. The loss of power which may be allowed in the line.
lliese six ooncfitions will determine a conductor of a definite cross sec-
tion, but no conductor should ever be used which is not of sufficient siae
both to insure the proper mechanical strength and also to prevent a dan-
gerous temperature elevation; the first condition is of particular impc»^
tance in overhead lines, the second in underground and interior wiring.
Assuming that the amount and distribution of the load and the timnt-
mission distance are known, the engineer has next to determine, what line
pressure to employ and wliat power loss to allow. To do this, he must
keep in mind two fundamental facts, namely, that the transmission syatem
is but part of the entire plant, and that the object of the plant as a whole
is to gain the maximum net revenue for the least expenditure of money;
also, that there is usually a limit to the capital available for the enter-
prise, which the first cost of the entire plant must not exceed, even thou^
a further increase of the capital outlay might gain a desirable revenue.
Consequently, in the selection of the pressure and efficiency for a distribu-
tion system, many complex factors enter, such as the nature of
the supply ot energy, the nature of the load supplied, the probability of
increase in the demand for power, etc., as well as the relative costs of the
various parts of the plant. Space does not permit of a detailed discus-
sion of all these factors here; it will suffice to state briefly the general Amer-
ican practice under the most common ocMiditions.
XIME PREAHURS. — To transmit a given amount of power a givioi
distance at a fixed efficiency, the amount of copper required will vary
inversely as the square of toe pressure. High pressure then means de>
crease in the cost of the conducting material, but an increase in the cost
of insulating the line and the rest of the system. As a general rule, espe-
cially in long distance transmission, the saving in copper as the pressure
is increased more than offsets the increased cost of insulation, up to about
60,000 volts, but in many cases other factors fix a much lower economical
limit to the line pressure. Recent improvements in the design of insula-
tors accompanied by a decrease cost of manufacture have raised the
economic limit of line pressure to 100,000 volts.
Direct Current jDtstrlbatlon. — On direct current systons supply-
ing directly incandescent lamps and small motors, the maximum pressure
allowable is 125 volts for two-wire distribution, 250 volts for three-wire
distribution; in certain cases where cheap power may be had, these figures
may be increased to 250 and 600 respectively. For large direct ctirrent
motor systems the corresponding figures are 500 to 600 volts for two-wire
and lOOiO to 1200 volts for three-wire ssrstems. The limiting transmisnon
pressure is fixed by the maximum pressure which can be employed on the
various translating devices, motors, lamps, and the like. Future devd-
opments in the latter may set a new limit tp the allowable pressure; in
fact, the compensating pole direct current motors now being placed on the
market will permit the use of pressure as high as 1200 volts for two-wire
and 2400 volts for three-wire systems. On circuits supplying direct cur-
rent series arc lamps, pressures as high as 5000 volts are used.
^
DIMENSIONS OF OONDUCTOBS. 261
AHmwwkaMng Current IMsteflNitioB* — The line pressure on thftt
part of an altematins current distribution system connected directly to
the various tranriating devices, motors, lamps, and the like, is fixed by
the practicable pressure that mav be used on these devices. For direct
distnbution for incandesoent lignting, the tine pressure between wtres
ihoukl not exceed 125 volts, or poesubly 260 volts if power is cheap and
220 to 2dO vdit incandescent lamps can be advantageously employed.
IHstrllbattoB l» Glttew. — In the larger cities the tendeney of modem
pcmetios (1907) is to generate three-phase alternating current at 11,000
or 13i000 volts (delta), and to transmit the power at this pressure either
U> fltatie transformer or rotary converter substations. For the dia-
tribution of direct current from rotary converter sub-stations see above
ondcr "line Pressure for Direct Current Distribution." At the statio
tnniformer sub-etatione the pressure is reduced to 2200 volts, and the
power tranamitted at this pressure to the centers of distribution, where
BaoUi«r reduction in pressure to about 125 or 260 volts takes place, and
firam here tlM energy is distributed directly to the lamps, motors, or
other translating device. In smaller dties, or when it is desired to employ
overhead lines entirely (mnoe 11,000 volts overhead in cities is not advis-
able), the sub-stations may be omitted and generators for 2200 volts be
OMd. Large induction motors may be suppued directly with 2200 volt
current, the very largest sometimes with current at 11.000 or 13,000 volts.
POfrSlK XiOM M THS ULM A. — To transmit a given amount
of power a given distance at a given pressure, the amount of copper
rsqoired wilTvary inversely as the amount of power lost in transmission.
Low effideney, therefore, means decrease in the cost of the conducting
material, but an increase in the central station output.
KAlvta'a Iiiftvr. — In genual, if two quantities A and B are both funo-
tioof of the same variable x, then the sum of A + B is a minimum when
tiie rate of change of A with respect to that variable is equal and opposite
to ths rate of change of B with req>ect to that variable, i.e., when
dA dB
dx dx
Numerous attempts have been made to apply this law to the determi-
uukn of the most economical efficiency for a transmission line. At first
a^t it would seem logical to proportion the costs of the central station
ud ttaasmismlon line so that the annual cost of delivering an additional
kilowatt of power by increasing the central station capacity will equal the
*Biam\ cost of denvering an additional kilowatt of power bv adding
OMe copper to the line. On this basis a very simple law is found to hold,
o>ndy, that the most economical current density per million circular
inileiB*
880
v/g-
vhtte K* M increase in annual charges on transmission line, resulting
from inereasing the weight of copper oAe ton (1^)00 lbs.). &nd Kp *" increase
m annual operating and capital charges on the central station, resulting from
inoeastng; the output one kilowatt.
rlj ^^* ^vcver, is true only for a given current; when the power sup-
^fn by any plant, and therefore the current, varies over wide Umits
^viqg the year, as is almost invariably the case, the current density as
^f^^naaed by the above law refers to the square root of the mean square
^v^t for the year, a quantity which can be determined only to the
'^''VBeet approximation.
Farther, the whole disciission of economical cross section is based on
two aasiimptions, usually unwarranted, namely, that the amount of capital
Avauable ia unlimited, and that a market can be found for the maximum
jvtput of the plant; it will evidently not be economical to install copper
to aave power which cannot be sold. In short, neither Kelvin's law nor
* The formula for aluminum is 106
v/^-
(
262 OOKDUCTOBS.
any modifioatton of it is a safe general guide in determining the proper
allowance for leas of power in the line. Each plant has to be oonaiderad
on its individual merits, and VariouB oonditione are likely to determine
thepreasure and loss in different cases.
MMmMhmtk^m JDIroct to Xnuulatanir Devtoee. — The power lorn
in a tranamission line also fixes the pressure loss or volts drop. In direct
current systems the per cent power loss equals the per cent pressure loss;
in an alternating current line there is also a fixed relation between the two,
see page 264. In that part of a distribution system connected directly
to the translating devices, lamps, motors, etc., the regulation of the line,
or the percentage pressure loss, must not exceed a certain amount oon*
sistent with reasonably ^dent operation of these translating devices.
For example, the maximum variation in pressure on incandescent lanqis
should not be more than 2 per cent; distribution lines which supply incan-
descent lamps and on which the pressure at the sending end is fixed,
should thereifore be of sufficient sise to insure a pressure loss of not over 2
per cent at maximum load. When a line supplies a large number of Istmpa,
all of which are not likely to be burning simultaneously, the per cent drop
in pressure for the connected load may be taken considerably greater.
For example, if the probable maximum load be figured at one third of
the connected load, a drop of 6 per cent for all lamps burning may be
allowed.
matiil»«tton in Ctonen^l. — The followinc discussion of the proper
?Dwer loss to allow in transmission lines is taken from Bell, "£3ectrie
6wer Transmission."
" The commonest cases which arise are as follows, arranged in order of
their frequency as occurring in American practice. Ekich case requires a
s. mewhat different treatment in the matter of line loss, And the whole
classification is the result not of a priori reasoning but of the study of a
very large number of concrete cases.
Cask I. General distribution of power and light from water-power.
This includes something like two thirds of all the power transmission
enterprises. The cases which have been investigated by the author have
ranged from 100 to 20,000 H.P., to be transmitted all the way from one to
one hundred and fifty miles. The market for power and light is usually
uncertain, the proposition of power to light imknown within wide limits,
and the total amount required only to be determined by future oonditionk.
The average load defies even approximate estimation, and as a rule even
when the general character of the market is most carefully investigated
little certamty is gained.
For one without the gift of prophecy the attempt to figure the fine for
such a transmission by following any canonical nues for maximum econ-
omy is merely the wildest sort of guesswork. The safest process is as fol-
lows: Assume an amount of power to be transmitted which can certainly
be disposed of. Figure the hne for an assumed loss of energy at full load
small enough to insure good and easy regulation, which determines the
quality of the service, and hence, in large measure, its ^p^wth. Arrange
both power station and line with reference to subsequent increase if needed.
The exact line loss assumed is more a result of trained iudgment than of
formal calculation. It will be in general between 5 and 16 per cent, for
which losses eeneratorc can be conveniently regulated. If raising and
lowering transformers ore used the losses of ener^^y in them should oe in-
cluded m tiie estimate for total loss in the line. In this case the loss in the
line proper should seldom exceed 10 per cent. A loss of less than 5 per
cent 18 sddom advisable.
It should not be forgotten that in an alternating circuit two small con-
ductors are generally better than one large one, so that the labor of in-
stallation often will not be increased by waiting for developments before
adding to the line. It frequently happenn, too, that it is verjr necessary
to keep down the first cost of installation, to lessen the financial burden
during the early stages of a plant's development.
Cass II. Delivery of a known amount of power from ample water-
power. This condition frequently arises in connection with manulactur-
ing establishments. A water-power is bought or leased in toto, and the
Sroblem consists of transmitting sufficient power for the comparativdy
xed needs of the works. The total amount is generally not laige, seldom
DIXSKSIOKS OF C0NDUCT0B8. 263
tfaaii a few hundred hone-power. Under these ciroumstanoee the
diottld be derigned for minimum fini coat, had any loss in the line
'Ue that does not lower the efflcienoy^enough to force the ubc
IMS of dynamos and water-wheels. These nses almost invari-
•re near *»^»Fg** toKether to involve no trouble in regulation if the
be chw deaopied. The operatijctf eTpense beoomes practically a fixed
fB io that the first cost only need be considered.
Sen phats are increasingly common. A brief trial calculation will
ov St once the conditions of economy and the way to meet them.
CissllL Dehwy of a known power from a closely limited source,
ease resembles the last, except that there is a definite limit set for the
mtfae system. Instead, then, of fixing a loss in the line based on regu-
and first cost alone, the first necessity is to deliver the re9uired
This may call for a line more expensive than would be indicated
•By of the formuls for maximum economy, since it is far more impor-
to avoid a siyplementary steam plant entirdy than to escape a con-
ible increase in cost of line. The data to be seriously considered are
COM of maintaining such a supplemoatary plant properly capitalised,
theprioe of the aoditional copper that render it unnecessary. Maxi-
' flficiency is here the governing factor. In cases where the motive-
is rented or derived from steam, formulas like Kelvin's may some-
be eonve&ient. Losses in the line will often be as low as 5 per cent,
isMs only 2 or 3.
Ciss rv. lAstribution of ]x>wer in known amount and units, with or
^^tboQt long distance transmission, with motive-power which, like steam
tetted water-power costs a certain amount per horse-power. Here the
idmtiim is minimum cost per H.P., and design for this purpose may
euiied oat with fair accuracy. Small line loss is generally desirable
the systenx is complicated by a long transmission. Such problems
/ w often appear as distributions only. Where electric motors are
enpetition with distribution by shafting, rope transmission, and the
' 2 to 5 per cent line loes may advantageously be used in a trial oom-
Tbe problem of power transmisson may arise in still other forms than
inst mentioned. Those are, however, the commonest types, and are
"^ to show how completely the point of view has to cnange when
. . ^ Ji^^ta under various dreumstanoes. The controlling element
.■tf be minimum first oost, maximum efficiency, minimum cost of trans-
' I, or eombinations oi any one of these, with locally fixed require-
as to one or more of the others, or as to special conditions quite apart
aayof them.
a T«ry many cases it is absolutely necessary to keep down the initial
*Mt, eren at a considerable sacrifice in other re^>ects. Or economy in a
*^Ks ffireetion must be sbught, even at a considerable expense in some
*^ direetion. For these reasons no rigid system can be followed, and
y* »i eoostant necessity for individual skill and judgment. It is no
**<MD>noQ thing to find two plants for transmitting equal powers over
*w ame distance under very similar conditions, which must, nowever. be
"WNPsd on totally different plans in order to best meet the requirements.''
264 00NDUCT0B8.
Let
CAMXJUMJLTMON OF TRAIVSIHIASKOM UOTBft.
Harold Pbndbr, Ph.D.
E — pressure between adjacent wires at receiving end in volts.
W « power delivered in kilowatta.
k a- power factor of the locui expressed as a decimal fraction.
A — cross section of each wire in millions of cireular mils.
w -a total weight of conductors in pounds.
{ <* length of cireuit (length of each wire) in feet.
R ■■ resistance of each wire in ohms.
U a" reactance factor of line ■■ ratio of line reactance to line resiatanes
(Table II).
Q ■> per cent power loss in terms of delivered povrer.
P » per cent pressure drop in terms of delivered pressure.
Put
F
IW
{kEV
In Table I are given formule for calculating the cross section, weight,
and power loss for any kind of conductor. The per cent pressure drop, /*,
can be readily calculated when the per cent power loss is known by means
of the formula
Where M and N are oonstants depending on the power factor (7;) and the
ratio tt of the line reactance to the line resistance, this ratio is called the
"reactanoe-f actor"; Tables III and IV rive the values of the constants M
and N for various values of k and (i. To a dose approzunation. ezospt
when the power factor is nearly unity, or the receiver current is leading, the
term NQ^ mtiy be nM^leoted. i.e.. in most practical cases P -■ MQ, The
complete expression P'^ MQ 4- NQ* ia exact in all eases for a 10 per cent
power loss; it is in error less than 3 per cent for any value of P less than SO;
m any case likely to arise in practice the discrepancy is less tlum 1 per cent
in the value of P. The exact expression for P in terms of Q is
P - Vi04 + 200 (1 + tt'bcHi + (1 + <i») kHi^ - 100
where I is the tangent corresponding to the oosine k. (See p. 276.)
Effect •r I^tne G»pttcMj.
The effect of the capacity of the line b to reduce the pressure drop, i.e.,
improve the regulation, and to decrease or increase the power loss depend-
ing on the load and ix>wer factor of the receiver. Let
6 - 2 ir/C X 10-«.
Where C is the capacity of the condenser in microfarads formed by any pair
of wires of the line, f is the fre9uency; 6 is called the capacity susceptance
of the line (for a single-phase line, the charging current is ba; for a three-
phase line the charging current per wire is 1.155 bE.
Table V gives the values of the capacity susceptance per 1000 feet of
cireuit for various sises of wire spaced various distances ajpart for a frequency
of 100 cycles per second; the values for other frequencies are directly pro-
portional. (Continued on p. 270.)
CAtCDLATlOV or TKAK8MIBSION LINES.
1
3
fell
i
1
!
t*
r
i»
S
i
li
3 o
z
3
S
1
8 o
S
8 r
fell
V
s
i
b,
K
3
S
i
I
S
ifclii
^ 1
8lo
=u
3
S
S -!
1
f
J
»
9
i
1
1
II
1
i
If
-■■3
I;
h
■Mi
&
fei
ii
6
1
1
CALCULATION OF TBAN8MISSI0N LINES.
267
Tabto lUL— Valm
Power Factors of Receiver.
Raactanoe
Fketon.
Current Leading.
Current Lagging.
tt-
90
95
98
100
98
95
90
85
80
70
0.0
0.1
0.2
.81
.77
.73
.90
.87
.84
.96
.94
.92
1.00
1.00
1.00
.05
.98
1.00
.90
.93
.96
.81
.85
.89
.72
.76
.81
.64
.69
.74
.49
.54
.59
0.3
0.4
0.5
.60
.65
.61
.81
.78
.75
.90
.88
.86
1.00
1.00
1.00
1.02
1.04
1.06
.99
1.02
1.05
.93
.97
1.01
.86
.00
.94
.79
.83
.88
.64
.60
.74
0.6
0.7
0.8
.64
.60
.72
.69
.66
.84
.82
.80
1.00
1.00
1.00
1.08
1.10
1.12
1.08
1.11
1.14
1.05
1.09
1.13
.99
1.08
1.08
.93
.98
1.02
.79
.84
.89
0.9
1.0
1.1
.46
.42
.38
.63
.61
.58
.78
.77
.76
1.00
1.00
1.00
1.14
1.16
1.18
1.17
1.20
1.23
1.17
1.20
.1.24
1.13
1.17
1.21
1.07
1.12
1.17
.04
.90
1.04
1.2
1.3
1.4
.84
.80
.26
.55
.52
.40
.73
.71
.69
1.00
1.00
1.00
1.19
1.21
1.23
1.26
1.20
1.32
1.28
1.32
1.36
1.20
1.31
1.35
1.22
1.27
1.31
1.09
1.14
1.10
1.5
1.0
1.7
.22
.18
.14
.46
.43
.40
.67
.65
.63
1.00
1.00
1.00
1.25
1.27
1.29
1.35
1.38
1.41
1.40
1.44
1.48
1.39
1.44
1.48
1.36
1.41
1.46
1.24
1.29
1.34
1.8
1.0
2.0
.10
.07
.03
.37
.34
.31
.61
.59
.57
1.00
1.00
1.00
1.31
1.33
1.35
1.44
1.47
1.50
1.51
1.56
1.59
1.53
1.58
1.62
1.50
1.55
1.60
1.39
1.44
1.49
2.1
2.2
2.3
-.01
-.00
.28
.25
.22
.55
.53
.61
1.00
1.00
1.00
1.37
1.39
1.41
1.53
1.56
1.50
1.63
1.67
1.71
1.66
1.70
1.75
1.65
1.70
1.75
1.54
1.59
1.64
2.4
2.5
2.0
-.13
-.17
-.21
.19
.16
.13
.40
.47
.45
1.00
1.00
1.00
1.43
1.45
1.47
1.62
1.64
1.67
1.75
1.79
1.83
1.80
1.84
1.88
1.79
1.84
1.89
1.69
1.74
1.79
2.7
2.8
2.9
-.25
-.29
-.33
.30
.07
.04
.43
.41
.39
1.00
1.00
1.00
1.49
1.61
1.53
1.70
1.73
1.76
1.87
1.91
1.96
1.93
1.98
2.02
1.94
1.98
2.08
1.84
1.89
1.94
3.0
3.1
3.2
-.36
-.40
-.44
-.01
-.02
-.06
.37
.36
.34
1.00
1.00
1.00
1.55
1.57
1.58
1.79
1.82
1.85
1.99
2.08
2.04
2.06
2.11
2.15
2.08
2.13
2.18
1.99
2.04
2.09
3.3
3.4
3.5
-.48
-.62
-.56
-.08
-.11
-.14
.32
.30
.28
1.00
1.00
1.00
1.60
1.62
1.64
1.88
1.91
1.94
2.10
2.14
2.18
2.20
2.24
2.29
2.23
2.27
2.32
2.14
2.19
2.24
i
268
OONDUCTOKS.
Tal*l« IV.-~Val««* of M.
Power Factors of Receiver.
Reactance
Factors.
Current Leading.
Current Lagging.
h-
90
95
98
100
98
95
90
86
80
70
0.0
0.1
0.2
.001
.001
.002
.001
.001
.001
.000
.000
.001
.000
.000
.000
.000
.000
.000
.001
.000
.000
.001
.000
.000
.001
.001
.001
.001
001
.001
^062
.001
.001
0.3
0.4
0.6
.002
.003
.003
.002
.002
.003
.001
.002
.002
.000
.001
.001
.000
.000
.000
.000
.000
000
.000
.000
.000
.000
.000
.000
.000
.000
.000
.001
.000
.OUU
0.6
0.7
0.8
.003
.004
.005
.003
.004
.005
.003
.004
.005
.002
.002
.003
.000
.001
.001
.000
.000
.001
.000
.000
.000
."boo
.000
.000
.000
.000
.000
.000
Am
.000
0.9
1.0
1.1
.006
.007
.008
.006
.006
.007
.006
.008
..007
.004
.005
.006
.002
.002
.003
.001
.002
.002
.001
.001
.001
.000
.001
.001
.000
.000
.000
.000
.000
.ouo
1.2
1.3
1.4
.009
.010
.011
.008
.010
.011
.008
.009
.011
.007
.008
.009
.004
.005
.006
.003
.003
.004
.002
.002
.003
.001
.001
.001
.000
.000
.001
.000
.000
.000
1.6
1.6
1.7
.013
.014
.016
.013
*.014
.016
.012
.014
.015
.010
.011
.013
.007
.008
.009
.005
.006
.007
.003
.004
.004
.002
.002
003
.001
.001
.002
.000
.000
.000
1.8
1.9
2.0
.017
.018
.020
.018
.019
.021
.017
.019
.021
.015
.016
.018
.011
.012
.013
.009
.010
.005
.006
.006
.003
.003
.004
.002
.002
.003
.000
.000
.001
2.1
2.2
2.3
.022
.023
.025
.023
.025
.027
.023
.02r>
.027
.020
.022
.024
.015
.016
.017
.011
.012
.014
.007
.008
.009
.005
.006
.006
.003
.003
.004
.001
.001
.002
2.4
2.6
2.6
.027
.029
.032
.029
.031
.034
.030
.032
.034
.026
.028
.030
.019
.021
.023
.015
.017
.018
.010
.011
.012
.007
.008
.009
.005
.005
.006
.002
.002
.003
2.7
2.8
2.9
.(M4
.036
.038
.036
.039
.041
.037
.040
.042
.033
.035
.037
.024
.026
.028
.020
.021
.023
.013
.015
.016
.010
.010
.011
.006
.007
.008
.003
.003
.004
3.0
3.1
3.2
.040
.042
.045
.044
.046
.049
.045
.047
.050
.040
.042
.045
.030
.033
.035
.024
.026
.028
.018
.019
.020
.012
.013
.014
.009
.009
.010
.004
.004
.005
3.3
8.4
3.6
.048
.051
.053
.052
.055
.059
.053
.056
.060
.048
.051
.054
.038
.040
.043
.030
.032
.034
.021
.023
.024
.015
.017
.018
.011
.012
.013
.005
.006
.006
or TRAHSHISSIUN LINKS.
ZSS 8|g SSS
SSS 33S Si;
s^^ sss sss s;gg gsi
S3S 338 SSS 1
;S5 ?3S nnS SS- 2~S S
sti Wi^ l?i sp ii2
270
COKDUCTOBS.
Using the same notation as given on page 264, putting H for the total
rasistanoe and X ( — tiR) for the total reaotanoe of each leg of the fins^
Decrease in per)
cent pressures p—
drop )
Decrease in per) ^^
cent power loss j
Single Phase.
50 bX
at -
2kHi
Three Phase.
100 bJt
2at -
km
where a «- 100 bR and ( is the tangent corresponding to the cosine k. (See -
p. 276.) The true regulation of the line is then P — p, and the true per
cent power loss is Q — q,P and Q being calculated by the formulae given
on pages 264 and 265. These formulsB are approximate, being deduced on
the assumption that the line oapBrcity can be represented by a condenser of
half the capacity of the line shunted across the line at each end, but they
are sufficiently accurate for any case likely to arise in practice. It is to be
noted that the chan^ in regulation is independent of the load and the
power factor, and is mdepenoent of the line resistance; the change in the
per cent power loss varies with both the load and the power factor.
IMrect Cmnremt, Tlu««* Wire B/mtmwi^. — Figure the wei^t and
eross section of the outer conductors as if the middle or neutral wve was
not present, putting E "- volts between outside wires. The neutral wire
is usually taken from one-third to full sise of each outer conductor. The
total weight of copper required will therefore be one-sixth to one-half
greater than the weight determined by the above formula.
Two-PIUMe, VQ«r« Wlr« System. — Treat each phase separately,
remembering that half the power is delivered by each phase, and B *
volts between diametrically opposite wires.
Two-Pliflwe, Three- Wire Sjetem. —
Let
E
V
pressure between each outer and middle wire at receiving end in volts,
pressure between each outer and middle wire at generating end in
volts.
Other symbols as above.
Then for equal rise of temperature in the three conductors the following
formtilsB hold. (The total weight of conductor required for this condition
is only a fraction of one per cent greater than for the condition of maximum
economy.)
Copper.
100 % conduc-
tivity.
20*» Centigrade
or 68« P.
Aluminum.
62 % conduc-
tivity.
20*" Centigrade
or68«F.
Any Material.
pB microhms
per cu. in.
6 — lbs. per
cu. in.
Cross section of each
outer wire in million j4i -•
CM* /
Cross section of middle 1 j _
wire in milUon CM. }-*«
Total weight in pounds w »
Total weight in pounds v> =
0.93F
1.60F
1.37pF
Q
1.26A,
9.85Mi
9A51F
Q
1.26^1
2. 971 Ay
AA51F
Q
1.26iii
30.7«4i
42.lpHF
Q
Q
Q
On the B. A S. sauge the middle wire is larger than each outer by one
number (see p. 146;.
HXTMBBICAIi BXAMPLEB OF CALCULATIONS. 271
• mr si«re Clrealte In ggrt— .
The above formalie and tables are also applicable to the ease of two or
more drouite in series, i.e., a transmisaion line and transformer, if we put
A ■■ Ri + R% 4* • • • •
Btlt + R^
iHm Ai, A,, etc., are the resistances of the separate eireuits and tu h, etc.
are the reactance factors of the separate drcuita.
IMrect C«rmaty Vw«-¥Ftre Sjateaa.
CoppsR WntBiL
Gnm W ^ 40 kilowatts.
E " 200 volts.
2-500 feet.
Q ■• 5 per cent,
^*" ^^ — (20oF •
Ch» section A - ^Q^^^'^ = 0.208 million CM.
o
The nearest commercial sise b No. 0000 B. db S. (see Table II) which has
to area of 0. 212 million CM.
Totol weight of copper w — 6.06 X 500 X 0.212 = 641 pounds.
Power loss Q - ^ Q^^^g '^ - 4-»2 per cent.
Prenure drop P »- Q "■ 4.92 per oent.
Prenure at senerating end — 1 .0402 X 200 » 209.84 volts.
{
Take tbe same constants as in the preceding case, considering E — 200
volta as the pressure between outer wires. If the neutral wire is to be half
ihe size of each outer, the total weight of copper required will be
641 + ^-801 pounds.
When the system is balanced there will be no current in the neutral wire
and the r^ulation and efficiency will be the same as above. If one side
(rf the 83rstem is ftilly loaded, and the other side not loaded at all, the volts
(hop in tiie loaded outer will be the same as if the system was balanced,
anoe the same current flows, and the volts drop in the neutral will be twice
the drop in the outer (same current and double resistance); hence total drop
will be 14.8 volts in 100 volts or 14.8 per oent. The power loss will also be
14.8 per cent or 2.96 kilowatts.
272 CONDUGTOIUS.
Copper Wirxs Spacbd 3 Fbbt Apabt.
QiTon _/ •> 25 cycles per second.
IT - 600 kilowatU.
E -i 10.000 Tolts.
I - 45,000 feet.
k i- 0.9, i.e., 00 per cent power factor.
Q "■ 10 per cent.
Th-n V - 45.000X500 ^
^*'*" ^ " (0.0 X lo.ooo)^ " ®-2^^-
CitMfl section A - ^ ^ ^^^'^^^ - 0.0678 miUion CM.
The nearest oommerdal siie is No. 2 B. & S. (Table II), which has an area
ol 0.0664 nuUion CM.
Total weight of oopper to « 6.06 X 45,000 X 0.0664 ^ 18.100 Ibe.
1? * ^1 j^ 2.08X0.278 o ^1
Exact power loss Q -• — ^ ^^^^ — — 8.71 per cent.
Reactance factor i^ - ^^ - 0.36. (Table II).
Therefore Af - 0.05 (Table III).
N - 0.000. (Table IV).
Then, neglecting the capacity of the line.
Pressure drop P - 0.95 X 8.71 - 8.27 per cent.
Pressure at generatmg end - 108.27 X 10,000- 10.827 volts.
Vwo«Pliaa«, Three- Wire Ayateai.
CopPBB WiBBS Spacbd 3 Fbbt Apabt.
Given / "■ 25 cycles per second.
Yr - 500 kilowatts.
E » 10.000 volts.
I - 45.000 feet.
h — 0.9. i.e., 90 per cent power factor.
Q >- 10 per cent.
Then
V - 45.000. X 500 _ J.
(0.9X10,000)* "■
Cross section of outers At - "^ iq " 0.0259 million CJI.
The nearest commercial sise is No. 6 B. & S. (Table II) which has an area
of 0.0263 million CM. The middle wire must therefore be No. 5 B. A S.
Total weight of copper w - 0.85 X 45,000 X 0.0263 - 11,600 lbs.
1? * 1 r. 0^3 X0.278 . p- .
Exact power loss Q — — K-Tji^ii^ "■ 0.87 per cent.
U.UzOO
The pressure loss will depend upon how the wires are arranged on the
poles. As a first approximation for anv ordinary arrangement, the reao*
tance of each phase can be considered the same as in a single phase S3«tem
with wires of the same cross section as the outer, spaced a distance apart
equal to that between each outer and the middle wire.
From Table II the reactance factor of a No. 6 wire correspondiii( to a
three-foot spacing and 25 cycles is
• t. - ^-0.15.
Whence Jf - 0.87.
NUMERAL EXAMPLES OF CALCULATIONS. 273
Th«n D«glectm« the eapeoity of the line, and uaing the approximate
fofmula P ^ -Az V*
gwirediop P - 9.87 X 0.87 - 8.69 per eent.
rnoBure at gieneratins end — 1.0859 X 10,000 — 10,869 volte.
I
GoppBB WiBBS Spaced 6 Kbit Apast.
Qiwi / i_ 60 cycles per aecond.
W » 10,000 kilowatts.
B - 60,000 volts.
I - 400,000 feet.
k — 0.86, i.e., 86 per cent power factor.
Q » 12 per cent.
^a^ J, _ 400.000 X 10.000 ^
(0.85 X 60,000>« •*^*
Owi aeetion ^ - ^-^^ X1.04 ^ ^ ^^ ^^.^^ ^^
-^^JJS*'^* commercial size ib No. 00 (see Table II), which has an ana
(10.133 milhon CJf.
Total vdght of copper w - 9.09 - 400,000 X 0.133 X 484.0001b.
Ntgltaing Kne eapacUy,
Eaet power loss Q - ^'^^^'^ - 12 per cent.
Beaetaoce factor «, -3.06x0.6-1.84.
Tbewfore M - 1.55.
^ N - 0.003.
fttwiredrop P - 1.55 X 12 + [0.003 X (12)1 - 19.0.
^M of U%B eapaeHy (see p. 204).
b -.00000089X0.6x400-0.000214.
(Table V).
R -0.0778x400-31.1 (Table II).
^j^^ X - 1.84 X 31.1 - 67.2.
Dwwse in per oent preasure drop - p « lOO X 0.000214 x 57.2 - 1.2.
a -100x0.000214X31.1-0.67.
t - 0.62.
DwBMsinperoent power loes-ff -2X0.67X0.62- ,-^^fP* ^ - 0.8.
\U. ooj* X12
Whence
Jae presBiiPB drop - 19.0 - 1.2 - 17.8 per oent.
jgqe power loss - 12.0 - 0.8 - 11.2 per cent.
ntmazt at generatmg end - 1 . 112 X 60.000 - 66.720 volta.
(
274
CONDUCrOHS.
TRAJTsmssioiv uoRns OF Kirowir comstahva.
The following formuUe and tables give an exact method of calculating
the efficiency and regulation of a tranamiasion line of known conBtanis,
in terms of the pressure between adjacent wires at the generating end of
line.
Given:
The kind of system, direct or alternating,
n — number of phases, for the ** single phase " system n -» 2.
/ B frequency in cycles per second.
V = pressure between adjacent wires at generating end, in volts.
W » power delivered in watts.
COS a ■■ power factor of load at receiving end.
R -■ resistance of each wire in ohms.
X = inductive reactance of each wire in ohms,
, Z — \/R^-^ X^ — impedance of each wire.
Required: E — pressure between adjacent wires at receiving end in volts.
/ ■» current per wire in amperes.
H •- total power lost in watts.
The values of E, /, and H are given in the table on p. 275. For approx-
imate calculations J can be taken equal to unity; the exact value of J is
given in the table below.
ITalnea of 9»
e
000
.001
.002
.003
.004
.005
.006
.007
.008
.009
.00
.01
.02
.03
.04
.05
1.0000
1.0001
1.0004
1.0009
1.0016
1.0025
1.0000
1.0001
1.0004
1.0010
1.0017
1.0026
1.0000
1.0001
1.0005
1.0010
1.0017
1.0027
1.0000
1.0002
1.0005
1.0011
1.0018
1.0028
1.0000
1.0002
1.0006
1.0012
1.0019
1.0029
1.0000
1.0002
1.0006
1.0012
1.0020
1.0030
1.0000
1.0003
1.0007
1.0013
1.0021
1.0031
1.0000
1.0008
1.0007
1.0014
1.0022
1.0032
1.0001
1.0008
1.0008
1.0014
1.0023
1.0034
1.0001
1.0004
1.0008
1.0015
1.0024
1.0035
0
.000
.002
.004
.006
.008
«
.000
.002
.004
.006
.008
.06
1.004
1.004
1.004
1.004
1.005
.29
1.102
1.104
1.106
1.108
1.110
.07
1.005
1.005
1.005
1.006
1.006
.30
1.111
1.113
1.115
1.117
1.119
.08
1.006
1.007
1.007
1.007
1.008
.31
1.121
1.123
1.125
1.127
1.129
.09
1.008
1.008
1.009
1.009
1.010
.32
1.131
1.133
1.135
1.137
1.139
.10.
1.010
1.010
1.011
1.011
1.011
.33
1.141
1.143
1.146
1.149
1.151
.11
1.012
1.012
1.013
1.013
1.014
.34
1.154
1.166
1.158
1.161
1.163
.12
1.014
1.015
1.015
1.016
1.017
.35
1.167
1.169
1.171
1.174
1.177
.13
1.018
1.018
1.019
1.019 1.020
.36
1.180
1.183
1.186
1.189
1.192
.14
1.021
1.021
1.022
1.022 1.023
.37
1.195
1.199
1.202
1.206
1.209
.15
1.024
1.024
1.025
1.025| 1.026
.38
1.213
1.216
1.220
1.224
1.227
.16
1.027
1.027
1.028
1. 02911. 030
.39
1.231
1.234
1.238
1.242
1.246
.17
1.031
1.032
1.032
1.033,1.034
.40
1.250
1.254
1.258
1.263
1.267
.18
1.034
1.035
1.03G
1.037 1.038
.41
1.272
1.276
1.280
1.285
1.280
.19
1.039
1.040
1.041
1 .042 1 .043
.42
1.296
1.301
1.307
1.312
1.318
.20
1.044
1.045
1.046
1.046 1.047
.43
1.324
1.330
1.336
1.342
1.349
.21
1.048
1.049
1.050
1.051 1.052
.44
1.356
1.363
1.370
1.377
1.385
.22
1.053
1.054
1.056
1.057 1.058!
.45
1.393
1.401
1.410
1.409
1.428
.23
1.059
l.OGl
1.062
1.063
1.06.5
.46
1.437
1.447
1.467
1.468
1.479
.24
1.066
1.067
1.068
1.070
1.071
.47
1.491
1.504
1.518
1.632
1.547
.25
1.072
1.074
1.075
1.076 1.078
.48
1.563
1.580
1.599
1.620
1.643
.26
1.079
1.081
1.082
1.083 1.084
.49
1.668
1.697
1.733
1.778
1.835
.27
1.086
1.094
1.087
1.096
1.089
1.098
1 .090 1 .092
.50
2.000
.28
1.099
i.iool
TRANSMISSION LINE OF KNOWN CONSTANTS. 275
i
!
I «
K}
SI
o
5
o
^^>3
a:
feNfe
8^
^
aq
^
kl«
Bq
> -S
|fiQ|S|fiQlS|flqiS|flqi'^J«il'> Wl*^
«
0)
ig
QQ
8fe
Skit:
oq .3
"§
I
I I
+
05
+
I
I
5.
I
03
CI
I
s
+
ft;
I
9
+
ft;
kl «
a
001 C
I
t
s
S
8
8
8
u
U
J"
.fci
c«
^
^
^
^
^
^
e«
a
-*
CO
^
c
1..?
1
J
o
1
1
t^
C4
CO
"♦
s:
<0
1 a
1 1
S I
.9 ;:
♦ S5
(
276
OONDUCTOBS.
i
ValBM
of taa a
(= t) tn toi
«••
f CM
«(=
k).
C08«
.000
.002
.004
.006
008
ooea
"k
.50
.000
.002
.004
.006
.008
.00
502
250
167
125
1.732
1.722
1.713
1.704
1.605
.01
166
83.3
71.4
62.5
55.4
.51
1.686
1.677
1.668
1.650
J -SI
.02
49.8
45.4
41.6
38.5
35.7
.52
1.642
1.634
1.625
1.617
1.600
.03
33.4
31.2
'29.4
27.7
26.3
.53
1.600
1.592
1.582
1.574
1.560^
.04
24.9
23.8
22.8
21.7
20.8
.54
1.558
1.550
1.542
1.534
1.520
.05
20.0
19.2
18.5
17.8
17.2
.55
1.518
1.510
1.503
1.494
1.487
.06
16.6
16.1
15.6
15.1
14.7
.56
1.479
1.471
1.464
1.456
1.440
.07
14.2
13.8
13.5
13.1
12.8
.57
1.441
1.434
1.426
1.419
1.411
.08
12.5
12.2
11.9
11.6
11.3
.58
1.404
1.397
1.389
1.383
1.375
.09
11.1
10.8
10.6
10.4
10.2
.59
1.368
1.361
1.354
1.347
1.3«
.10
9.96
9.76
9.57
9.38
9.21
.60
1.333
1.326
1.319
1.312
1.306
.11
9.03
8.87
8.78
8.56
8.41
.61
1.299
1.292
1.285
1.279
1.27S
.12
8.26
8.14
8.01
7.88
7.75
.62
1.265
1.258
1.251
1.246
1.230
.13
7.63
7.51
7.40
7.28
7.18
.63
1.232
1.226
1.219
1.213
i.aoo
.14
7.07
6.97
6.87
6.77
6.68
.64
1.200
1.194
1.188
1.181
1.175
.15
6.59
6.50
6.41
6.34
6.25
.65
1.168
1.162
1.156
1.150
1.144
.16
6.17
6.10
6.02
5.94
5.87
.66
1.138
1.132
1.126
1.119
1.113
.17
5.80
5.73
5.66
5.60
5.53
.67
1.108
1.102
1.095
1.09O
1.084
.18
5.47
5.40
5.34
5.28
5.23
.68
1.078
1.072
1.066
1.060
1.055
.19
5.17
5.11
5.06
5.00
4.95
.69
1.048
1.043
1.037
1.031
1.02S
.20
4.90
4.85
4.80
4.75
4.70
.70
1.020
1.014
1.008
1.002
.998
.21
4.66
4.61
4.57
4.52
4.47
.71.
.992
.986
.080
.976
.070
.22
4.43
4.39
4.35
4.31
4.27
.72
.964
.968
.953
.947
.042
.23
4.23
4.19
4.15
4.12
4.08
.73
.936
.031
.925
.920
.014
.24
4.05
4.01
3.98
3.94
3.90
.74
.909
.904
.898
.803
.887
.25
3.87
3.84
3.81
3.78
3.75
.75
.882
.876
.871
.866
.861
.28
3.71
3.68
3.66
3.62
3.59
.76
.855
.850
.845
.839
.834
.27
3.57
3.54
3.51
3.48
3.46
.77
.829
.823
.818
.813
.807
.28
3.43
3.40
3.38
3.35
3.33
.78
.802
.797
.792
.786
.781
.29
3.30
3.27
3.25
3.23
3.20
.79
.776
.771
.765
.760
.755
.30
3.18
3.16
3.13
3.11
3.09
.80
.750
.745
.740
.735
.729
.31
3.07
3.04
3.02
3.00
2.98
.81
.724
.719
.714
.708
.703
.32
2.96
2.94
2.92
2.90
2.88
.82
.698
.693
.688
.683
.677
.33
2.86
2.84
2.82
2.80
2.79
.83
.672
.667
.661
.656
.651
.34
2.76
2.76
2.73
2.71
2.69
.84
.646
.641
.635
.630
.625
.35
2.68
2.66
2.64
2.63
2.61
.85
.620
.614
.609
.604
.598
.36
2.59
2.58
2.56
2.54
2.53
.86
.593
.588
.583
.677
.672
.37
2.51
2.50
2.48
2.46
2.45
.87
.667
.562
.556
.651
.545
.38
2.43
2.42
2.40
2.39
2.37
.88
.540
.534
.529
.624
.518
.39
2.36
2.35
2.33
2.32
2.31
.89
.512
.507
.601
.496
.490
.40
2.29
2.28
2.26
2.25
2.24
.90
.489
.479
.473
.467
.461
.41
2.23
2.21
2.20
2.19
2.17
.91
.456
.450
.444
.438
.432
.42
2.16
2.15
2.14
2.12
2.11
.92
.426
.420
.414
.408
.401
.43
2.10
2.09
2.08
2.06
2.05
.93
.395
.389
.383
.376
.370
.44
2.04
2.03
2.02
2.01
2.00
.94
.363
.356
.350
.343
.336
.45
1.98
1.97
1.96
1 95
1.94
95
.329
.3M
.314
.307
.290
.46
1.93
1.92
1.91
1.90
l.HO
.96
.292
.284
.276
.268
.259
.47
1.88
1.87
1.86
1.85
1.8t
.97
.251
.242
.232
.223
.213
.48
1.83
1.82
1.81
1.80
1.79
.98
.203
.192
.181
.169 .156
.49
1.78
1.77
1.76
1.75
1.74
1 .99
.143
.127
.110
.090 .063
NoTa.— ThiB table is to be u^ed like a table of logarithms. e.g., the
tangent corresponding to coe « ^^ .816 is .708.
TRANSMISSION LINB CALCULATIONS. 277
I When the tnoatadnc devices, whether lamps or motors, are scattered
'~nier a ooosidenble area, the usual method of supplying them with power
to ran a single feeder to some point near the ** center of gravity " of
load, and from this center run out branches to feed groups of lunps or
in paraUd. The center of gravity of the load can be readily deter-
Bs follows:
Let Wi, tPa, 10s, etc.
icpresSDt the individual loads,
i vkI Xi, za, X9, etc.
: Bad Vu V% VH. etc.,
i icpresent the distances of these loads from any two fixed lines OX and OY
! at ri^t anfl^es to eadi other. Then the center of gravity is that point which
I k the distance
_ ».«H +*">*+ **^+ ■■■ from OX
mi r. - »'«H+«^+«^+--from OY.
I
The center of gravity of the load is by no means always the most economl-
I esl beation for the center of distribution, as considerations of the relative
eoit of establishing the cent^ at this point in comjparison with the cost at
oth« points, the probable change in the distribution of the load with the
grovth of the system, etc., have all to be taken into account.
The general scheme of feeders, centers of distribution, and branches
caa be developed still further, and sub-centers, sub-feeders, etc., estab-
fidied, until a point b reached where the saving in the cost of copper is
hifiiiiwd by the increase in the cost cd the centers of distribution.
CalcvlatloM at CrOM Section, W«lrliti *c.
When a transmission line is loaded at more than one point, the conductor
ihooki have such dimensions that the pressure drop at the end of the line,
vhcn the line is supplsring the maximum load at each point, shall not exceed
ft era amount. Whether the conductor shall be mode of uniform section
thnndiout the length of the line, or be reduced in sise as the current
» Muried diminishes, will depend on the r^tive amounts of energy su]^
pBed at, and the distances between, the various points at which the line is
bided. Below wiU be found formulsB for determining the weight and
crasi ssetion of a line of uniform cross section, and hawng no returnee,
■ipplyuig a distributed load. When the line has no inductive reactance
the vei0^t and cross section of the conductor for a given pressure drop
i ftre to a dose approximation independent of the power factor of the loads
*t the various points. When the line has reactance, the formulse^ will mve
only a first approximation to the correct weight and cross section. The
nor invotved can bA determined by considenni^ each section of the line
Mperateiy, and calculating the drop in each section, assuming the dimen-
lioM civen by the approximate formulae. (See page 264.) If the pressure
yop at the end of the line thus calculated diners considerably from the
pcnmaable drop ^ven, chooee a lar^r sise wire and make another trial
•ilealation, etc., until the proper sise is found.
278
CONDUCrOBS.
u
i.
<— il — *-
2
-h
Fio. 15.
In the figure let G be the generating end of the line; / the far end off
Given:
B — pressure between adjacent wires at far end of line In volte. '
Wt, Wf, W9, etc., the loads in kilowatts at the points 1, 2, 3, etc.
^1 ^ ^ eto^ the distanoes of these points from the generating end ia
feet.
P ■- per cent pressure drop at far end of line in terms off ddivend
pressure.
Required:
A — cross section of each wire in million CM.
to » total weight of conductors in pounds.
Put ^
TT - TTi + TFa + TTs + . . . total power delivered in kilowatts.
I " li + It + h + ' ' • total length of drowt (length of each wire) infeet
kWi + hWt + ItWi + ...
F -
E^
Then, for a line havino no reactance:
Cross section in million
CM
Total weight of conduc-
tors
Or total wei^t of con-
ductors
Vlar«« Plfta««.
Cross section in million
CM
Total weight of conduc-
tors
Or total weii^t of oon-
ductoxB
A -
w •»
u> —
A -
w —
Copper.
100% conduc-
tivity.
20° Centigrade.
2.08F
6.06M
12.6F{
~P
1.041^
P
0.09U
0.48F2
Aluminum.
62% conduc-
tivity.
20**Centigrade.
3.34F
1.83U
6.11FZ
1.67F
~
2.741A
4.58F2
Any MatenaL
P"B meitihnis
per eu. in.
^■"Ibs.per
ou. in.
3.06pF
P
18.9<Li
P
1.53pF
P
28.3aLi
4A.2pnF
^
TRANSMISSION LINE CALCULATIONS. 279
When the distanoes between the points at which the line is loaded are
eooildetmble, it is ustially advantageous to taper the conductor; the most
^ff^f^^m'"^^ pressure drop per section must be determined, and each section
of the line calculated mdependently. The following formuke give the
iDost eeooomical division oi the drop, taking into account the cost both
o( conductor and insulation. For snort runs the saving in cost of con-
ductor and insulation may be more than offset by the extra cost of handling
tvo or more sizes of wire.
The same notation as in the preceding paragraph Is used. In addition,
let
Vt^Wi-^- TTj + TTi 4" • • • "• total load in kilowatts at and beyond point 1 .
(^ <- ITs 4- Wt +..."*> total load in kilowatts at and beyond point 2.
Ob - YFs + ... as total load in kilowatts at and beyond point 3.
eU.
A| B 2| aa distance in feet from generating end to point 1.
Af — 4 — 'i ■" distance in feet between points 1 and 2.
^ " ib — b -■ distance in feet between points 2 and 3.
e.
Then the most economical per cent pressure drop for the tth section is
Ai a mtei the sise of wire used in wiring ordinary bufldings for light
•ad power as fixed by the permissible heating of the wire (see p. 265) is of
niaeDt nse to keep the pressure drop within the prescribed limit, since
the distances the wires are run are comparatively short. It is always well,
bovcfsr, to calculate the drop in the heaviest and longest circuits, to be
■OR that one is on the safe side as regards regulation.
Cksrt wad Val»l« for CAlcelatfns' Altcntafing'-Cnrreat
Baxph D. Mkbshon, in American Electrieian,
Aeaeoompanying table, and chart on page 232 include everything neces-
wy for ealcalatlxig the copper of alternating-current lines.
Ihetehns, reslstanoe volts, reelstanoe E.M.F., reactance volts, and react-
iKeEJI.F., refer to the voltages for overcoming the back £.M.F.'8 due to
t«iit«Dce and reactance respectively. The following examples Illustrate
Um use of the chart and table.
FBOBLEJf.— Power to be delivered. 260 k.w.; E.M.F. to be delivered, 2000
Tolti; distance of transmission, 10,000 ft.; size of wire, No. 0; distance be-
tVMD vires, 18 inches ; power factor of load, .8 ; alternations, 7200 per min-
ote. Knd the line loss and £rop.
The power factor is that function by which the apparent power or volt-am-
pereg most be multiplied to give the true power or watts. Therefore the
qiPimt power to be delivered 18^^^ = 312.6 apparent k.w., or 312,600
tolt«iiperei, or apparent watts. The current, therefore, at 2000 volts will be
~j|ilip= 166.25 amperee. From the table of reactances, under the heading
^ISiBches,** and eorreBponding to No. 0 wire, is obtained the constant. .228.
Msriag the iMtmettooj of tM table in mind, the reaotanoe volts of thif
280 OONDUCTOBS.
line are 166.26 (ftrnperoB) x 10 (thousands of feet) x '228 = 366^ Tolto*
are 17.8 per cent of the 9000 TOits to be deUvered.
From the oolamn headed " Besistanee Volts," and oorrespondiiiff to Kaj
wire, is obtained the constant .197. The reslstanoe Tolts of the line
therefore, 166.25 (amperes) x 10 (thousands of feet) x .197=807.8 Tolta, ^
are 15.4 per cent of the 2000 Tolts to be delivered.
Starting, in accordance with the instructions of the sheet, from the
where the vertical line, which at the bottom of the sheet is marked **]
Power Factor .8," intersects the inner or smallest circle, lay off horixoni
and to the right the resistance E.M.F. in per oent (16.4), and " from
point thus obtained," lay off. vertically the reactance E.M.F. in per
(17.8). The last point falls at about 23 per cent, as given by the circmar «
This, then, is the drop in per oent of the E.M.F. acliverea. The drop in
28
oent of the generator E.M.F. is, of course, , = 18.7 per oent.
The resistance volts in this case being 3077, and the eurrent 166.25
peres, the energy loss is 807.8 x 166.26=48.1 k.w. The percentage loss
48 1 __
^iqI^i = 16.1 . Therefore, for the problem taken, the drop is 1S.7 per <
and the enercy loss is 16.1 per cent.
If the problem be to And the siae of wire for agiven drop, it must be sob
by trial. Assume a sixe of wire, and calculate the drop in the manner aboi
indicated ; the result in connection with the table will show the direct'
and extent of the change necessary in the siae of wire to give the reqi
drop. '
The table is made out for 7200 alternations per minute, but will answi
for any other number. For instance, for 16,000 alternations, multiply
reactances by 16000 -f 7200 = 2.22.
As an illustration of the method of oalculating the drop in a line and
former, and also of the use of the table and chart in oalculating low-roll
mains, the following example is given :~
Pboblbm . — A single-phase, induction motor is to be supplied with 20
Sres at 200 volts ; alternations, 7200 per minute ; power factor, .78. '. _
itance from transformer to motor is 160 ft., and the line is No. 5 wire,(
inches between centres of conductors. The transformer reduces in the
900O : 200, and has a capacity of 25 amperes at 200 volts ; when deliverii
eurrent and voltage, its resistance £ JC .F. is as 2JS per oent, and its rea
E.M.F. 6 per cent, both of these constants being furnished by the mak4
Find the drop.
The reactance of 1000 ft. of circuit, consisting of two No. 6 wirea, 6 ini
IfiO
I4>art, is .204. The reactance-volts, therefore, are .204 x jg^ X 20= .61 Tolta.
The resistance-volts are .627 x j^ X 20 = 1.88 volts. At 26 amperes, the re>
tlstanoe-volts of the transformers are 2Z per cent of 200, or 6 volts. At 90
amperes they are ^ of this, or 4 volts. Similarly, the transformer reactance
volts at 26 amperes are 10, and at 20 amperes are 8 volts. The combined re-
actance-volts of transformer and line are 8+ .61 = 8.61, which is 4.3 per cent
of the 200 volts to be delivered. The combined resistance-volts are 1.88+4,
or 6.88, which is 2.94 per cent of the E.M J. to be delivered. Combining these
quantities on the chart with a power factor of .78, the drop is 6 per cent of
the delivered E.M.F., or t^ = 4.8 per cent of the impressed E Ji.F. The
transformer must therefore beaupplied with 2000 -r .962 = 2100 volts, in order
that 200 volts shall be delivered to the motor.
To calculate a four-wire, two-phased transmission eirouit, oomputo, aa
above, the single-phased circuit required to transmit one-half the power at
the same voltage. The two-phase transmission will require two such
eireuits.
To calculate a three-phase transmission, compute, as above, a single-phaae
eirouit to carry one^half the load at the same voltage. The three-phswe
transmission will require three wires of the slse obtained for the sliigia-phaae
circuit, and with the same distanoe (triangular) between centres.
By means of the table calculate the Re*i$tanee- VoU$ and the
1
TRAN3MtaSION UNE CALCULATIONS. 281
i
i
»
CONDUCTORS,
TBANSMIBSIOH LINE C
wine suma publiihed by the 0«aeral E]«tric Compuiy (ira
al «>pp«T per kitowatt (Mivmd for varioua paroeatace* of powv
ioiB preaaun indieDU (volla per mile). It i* lo be Dat«d thM
I are eorrecC only for unity poim [actor.
liui Leas in par cent of Pomr Delivered-
i
i
{
rrealndlcateTOltapernilte, I.e., potential
iRlit of eoppar, potBiiHa!, sad Udb Iobb ws
CarTca are «oiTeet onW (ot 100% power factor. Tirn-piiiih«, Biiigle-pbflM
or CODtlanaiu eurrenl iiuumlsaion requires one-third more cupper. E%
Ui beni allowed for eag and tie virea In welahta of copper given.
ExAMPUt Aaaamlng that 1000 k«, at lOloOO volte are to tie dellTered
ortt a Uue 10 mllea lon( irltb S% loH, wo bavo -"fl"^!!^'- - "W Tolti
per mile. Looking on tbe ICOO TOlt curve, we flna G% line loee oorreapondl
la SI lU. of copper per kilowatt delivered.
284 CONDUCTORS.
DDXBiunEHrAxioir or bwmm oc comtircvoits rom
PAiftAULJBii DiATimuanioir or doibct
Beaifltanoe of one oir.-mll-foot Of pure hard drawn copper wire
at aO» C. (68° F.) (see page 200) lO^ohiiit
Resifltance uz one cir. -mil-foot of pure hard drawn oopper wire
at 97JS per cent oondttctirity 10.6 obiot
Thus the resistance R of any hard drawn copper conductor is,
and
or
^ length in feet X 10.8
cir. mils '
Clr. mil. - '^i^ *" '«*' ^ "•*
Length in feet
Ji
R X cir. mils
10.8
Let / — Current in amperes flowing in circuit.
^ . Watts, power in circuit.
E « Volts at reoelying end of circuit.
V — Volts drop in circuit.
A <" Cir. mils area of wire.
P •- Per cent of power lost.
p >■ Per cent of volts drop in circuit.
d — Distance from generating to receiylng end of circuit or center
of load»^ the length of wire if the load is uniformly dlA*
tributed.
21.6-10.8X2.
Then
or
or
. 21.6 X dX /
^ - ^ .
. 2160 X J X /
^ PX~B •
2160 X dxjr
^ 21.6 Xd XI
V -^ .
100
T&AK8P08ITI0N OF LUfXS.
■mAirspoaxnoH or iMMxm.
F. F. Fowi^
of OTarhflad linn ii ft nwana for eliminatiiis in
uniwBaUy aroployttl on tcLopbone linM aod Qi
only und(
Lnd th« muTHtJo fields about & lins econAtlD^ of a luulo
ia eomplaMd thcoucli the Muth. Fif . Ja ibon tlu Gald*
Fig. 18. Fio. 10.
>boM 111* two wira <4 a malallio alrouil. will) «tual and oppoaiM curmila
in Iba vim and no ceriDsclioii U> aatth at any poinl oa the oiniuit. lo
M^booT this CDndition ri lins is termad " baUncnd."
tat iotendty of ths inducsd eumnt dspends on thg aileot to which th«
; Md <rf ana eirouit thnadi into the othsr. and tbonfore upon the diitanoe
tMnea the wires and the eitent to which Ibsir fields spnad bio the sur-
nmdiiif dieleetrie. The ipnod ot the Geld of a linila-wire circuit, shown
n Rf. IS. is equsl to that ol an imuinBry mstaliiB circuit c^ which one
I vm m the sidsejng overiiead wli« and the other a ■'"*"*r wire puaUd to
c I
i
i
1 «>
1*
Fro. 2a
Um nistins wlra but beneath the eanh's surfaos a distance equaJ to tha
•JevmOoB rf the eiiitiTis wire. The tpr«Kl of the field of .initle-irire eartii-
"ratD cireuits is therefore eioenive.
fif. 20 shows the maoner of neutralisinB mutual inductive effects of
Iw DMalGe rircnits by the tianspojition ofthe wires nf one circuit. By
UK Inaqxisitian of Rircn 3 and 4 midway in the section the licld nf the
BTtrnt M from a lo fc is oppomle in it4i direction and polarity to that be-
l<nai b and e. so tliat the induced E.M.F.'i in circuit 1-^2 between a and b
*" oppoate to thoM between b and c The same is true of induced E Jd.F.'a
286
CONDUCTORS.
V ^^u^} ?^ prod***^ ^y mrouit 1-2. Tha effecta would have been idea-
ti<^I had 1 and 2 been transpoeed instead of 8 and 4.
Kefemng to Fig. 20, the Itm^th of the section I must not be so sreat tha
the current and the potential in the section (t-b are materially diffmnt fnm
X
X
-f-
-4^
D
•«-
t
3!)
Fia. 21.
WnSi^^'^^^^ i^cL^^^tj^SeTXSsSrbT^^^r 5 ^
Se^tinS^Vnf'i?^' '^* ™^«. ^.^*»« measurem^Irof a^disSSSe «
iJliS^l;?***^ **^ **°if " ^°* * multiple of Z. the last section may be Uken
somewhat longer or shorter than the stand»^ section, but it shduW bs S
Fio. 22.
Fig. 22A.
more than one and a half regular sections nor less than half a regular see*
tion. Fig. 21 shows a line haying four and a quarter transpositio?seotiSL
A transposition at the junction of two adjacent sections is wi^iTnnt *^M«t
on those sections, therefore the Fig. 22A ii ^uivSeLTto F^S-^^ fwl
A
^ 4^
3
Fio. 23.
TBABTSPOSITION OF LINES.
287
^
b tins only when the standard section length is not in excess of that per-
misrible, as outlined above.
The transposition of power and lighting drouits is not often necessary.
In Qomplicated networlu it is almost unKnown, because the troublesome
C
n
^ ^ ^,
w
Fig. 24.
oreoits are asoally short. At the frequencies used in power and lighting
the. transposition section may be several miles in length, much longer than
in tdephone practice.
The transpctfition of polyphase lines is sometimes employed to balance
ndafitive effects which would otherwise be troublesome.
!;
5^
K
V—w-'
■H4-
-^ 4
■2
■;3
I
Fio. 25.
F%. 23 shows a balanced three-phase line, which would be transposed
QOly to avoid inductive interference with other lines.
Fig. 24 shows an unbalanced three-phase line and Fig. 25 shows the
BvUiod of transposing it to secure a balanced circuit, or eaual inductance
per phase. Fig. 28 illustrates the application of the section shown in Fig. 8.
I
1—
4 1 -
Fia.26.
3E
Tlis transposition of telephone lines becomes a complicated problem when
tfane are many circuits, as it is necessary to arrange the transpositions in
nidi s manner that each circuit is transposed with respect to all the others;
r
288
GONDUCTOB8.
Also the drouita that are adjacent must have more frequent relative iraae*
poeitiona than those further apart. The method of deriving differently
transposed types of circuits is given in an American Institute paper on
"The Transposition of Electrical Conductors." *
Fig. 27 shows fifteen different types of transposition. The "expoeure,"
as it is termed, of circuit 1 to circuit 2 is i; of 1 to 3 is i; of 2 to 3 is i;
because a transposition at the junction of two sections, ea<ui tran^poeed at
1^
Komberof
Traiufposltioitt
0-
i:
81
e:
t:
&:
9:
ID'
XL
DC
3C
X
(^
I-
XZXIX
XZXZDC
X
3CZ3CDC
i^^^H^^^^^H^^^M
DCZDCDC
y — x—r
Tjpe BerlTatici
No. ofTn»
no
:8 - n- «
1^5 -1+4
ZZI6- «-^4
=17 -8 + 4
Dczrs
xz:9 » 1 + 8
DCZ:10"8 + 8
■^■^■■^^■^i^^^
X.X X.
^^^^a^^^^mm^^m
xzxzx
Dczxzx:
^^H^H^klV^/^M^B^«^B^\^^B^\^l^^^^
DCDCDC
XZIU- 8 + 8
:i8a4 + 8
lis- 6+8
18
11— y V Y-v—v— >r-y y— v— r-Y-^x— Y-n< 14»ii -i- 8
151 „ )R X y. x X tLJH ■ ji .rnt X X-IXI-X— x m* 7 + 8
i^^
^
DCZ318-7
Fia.37.
ita eenter. has almost no beneficial effect. The exposure of 1 to 5 is f; of
2 to 6 and 3 to 7, ^; of 2 to 8 and 2 to 9. A ; and so on. The tabulated ex-
postves are given m Fig. 28, in terms of the length 1 of a transposition
tion. The method may be extended as far as desired, but 15 types ars
usually sufficient.
It has been found' experimentally that one-fourth mile exposures are sat-
isfactory in telephone work for circuits immediately adjacent to each other;
for circuits not adjacent the transpositions mav be farther apart. The
distance I in Fig. 27 may then be taken at four miles, and fifteen differently
transposed types are available. The method may be extended to thirty-
two types with an eight mile section. The eight mile section is rather
cumbersome for most work and a four mile section is more adaptable to gen*
eral conditions.
The transposition of telephone circuits a^inst power and lighting circniti
should be treated on the sectional principle. It is possible to improve
some cases by reducing the separation between the wires of the power or
lighting circuit; this is usually the cheapest plan if the transposition section
• Vol. XXIII. page 659, Oct. 28, 1904.
■TBAMBPOSITIOH OV LINB8.
fiOOoTia duuibui
A^ poiQl* when telephoiie Ud<
Uiapbooa dreuit*. For the toIU^v* len thui
Expoaiin otTyiM No.
To
0
1
.
.
.
•
.
a
,
10
11
i:
13
,4
1
-
i
i
4
!
i
t
i
)
-
«
*
i
1
i
1
7
i
*
t
t
I
i
1
B
i.
A
A
A
A
A
A
A
.
A
A
A
A
A
A
A
A
10
1,
A
A
A
A
A
A
A
11
A
A
A
A
A
A
A
A
IJ
A
A
A
A
A
A
A
A
»
13
A
A
A
A
A
A
A
A
*
i
14
A
A
A
A
A
A
A
A
*
i
t
IS
A
A
A
A
A
A
A
A
1
1
i
i
i
m two mdiictjc
Tha procedure ie to hr
• in the dinr
on will Dot b
jutinc circaiU, u on oppoaite ndea of theee
nee are ncpoMd to oompU»ted dietributk
lie, it DO( effeetiTe.
290
GOKDUCTOB8.
B
s
1
1
ladoctton
8«otioa
•*•
Indpotton
I r.
Indaetton
Sootion
Induction
Fto. 20.
Mfavara lif ■•• — The condaeton on this line are bare eables of II
Btrands, equlTalent to 360,000 circuit mils, and are arranged aa shown in
the fonowing diagram. The first arrangement was with two three-wire eir-
FlO. dO. Niagara-Buffalo Line. 11000 to 22000 VolU.
onlts on the upper cross-arm, the wires being 18 inches apart. Bo mueh
trouble was experienced from short ctrenits by wires and other material
beins; thrown across the conductors, that the middle wire was lowered to
the bottom cross-arm as shown, 'since which time no trouble has been
experienced. With iK>roelain insulators tested to 40,000 volts there is no
Appreciable lealcaffe. These circuits are Interchanged at a numbs* of
points to avoid inductive effects.
TRAirSPOaiTIOIT OF LINKS.
291
Ctvcoite* — « The diagram (Fig. 81) shows another ar-
xangement now eeldom used although it nuikes lines oonyeniently aooeesible
for rqpaira. Under the ordinary loads usual in the smaller plants the unbal-
andiig ^ect is so small as to be inappreciable. .
Fio. 31. Convenient Arrangement of Three-Phase Lines fori
6000-10,000 Volts.
.X. •&!
• a.
I
Fio. 32. Arrangement of Two-Phase Circuit. No Reversal
of Phases necessary.
(
Tw«.|Phae«, Conr-is'lre Clrculte. — The arrangement of conductors
•nown in Fig. 32 is probably the best for two-phase work; as no reversals
cK wires are needed, the inductive effects of the wires of one circuit on those
« the other are neutralised.
292 CONDUCTORS.
Vwo-Pluw« Ctvcoltw te Wame P1»b«i. — If the phases are traal
u separate cireuits, and earned well apart, as shown in Fig. 33, the inl
PHASE B.
18^^ Ht 18^
Fio. 33.
enoe is triflins; and should the loads carried be heavy enough to cause notioe*
able effect, the reversal of one of the phases in the middle of its length will
obviate it. The following diagram illustrates the meaning.
PHA8E A.
1
PBA8E B. >(^
Fio. 34. Arrangement of Two-Phase, Four-Wire Circuit with Wires on
same Plane. ^Wires of One Phase should be interchanged at the Middle
Point of the Distance between Branches, and between its Origin and
First Branch.
Messrs. Scott and Mershon of the Westinghouse Electric and Manufactur-
ing Co. have made special studies of the question of mutual induction of
circuits, both in theory and practice; and their papers can be found in the
files of the technical journals, and supply full detau information.
Mataal Hevtrallaattoii of CapACtly aad ladvcteace. — In
order to completely neutralise j^hase displacement due to distributed in-
ductance a distributed capacity is essential. Localised cai>acity can, how-
ever, produce a partial neutralisation. Ehceessive distributed cafiacity
can also be partially neutralised by inserting inductances at proper inters
vals. In treating of local neutralisation of capacity by inductance, the
assumption is frequently made that the capacity is constant irrespective
of the voltage, and that the inductance is constant irrespective of the
current. Under these conditions neutralisation can be obtained. As,
however, inductance is dependent upon the permeability of the assodated
magnetic cirouii, and permeability varies witn the saturation of the iron. —
that is, with the current, — * complete neutralisation cannot be obtained
with iron inductances.
Over-«xcited sjaichronous motors, or sjrnchronous converters, take cur-
rents which lead the electromotive force impressed upon them, and they
therefore o|>erate as condensers, and they may be utilized advantageomly
in neutralising the line inductance. The power factor of the transmisaion
ssrstem can therefore be varied by varying their excitation.
BELL WIRING.
293
COVBJUBl^ GAJBUM.
Jobs T. Uorsib {Slectridant London) gjves the following formula, con-
finned by experini«ntfl, for the loas of power in the lead sheath of a three-
Amdoelor cable.
Let J « current in amperes.
/ — frequency.
I — length of cable in 1000 ft.
£ » thic
Thco:
t » thickness of sheath in mils.
Watts lofls - 123 X lO'^Pf^lfi-^
If the eaUe is placed in^ an iron pipe the loss is increased about 75%.
]s;bia iraurare.
The following diagrams show various methods of connecting up-call bells
for different purposes, and will indicate ways in which incanaescent lamps
Bsy sho be eonnected to accomplish different results.
=4
Q=W
fim. 35. One BeO, qpemted by
One Push.
Fia. 96. One Bell, operated by
Two Pushes.
G
i
P>B. 37. Two Bells, operated by
One Push.
Fio. 38. Two Bells, operated by
Two Pushes.
When two or more bells are required to ring from one push, the common
pnetice is to connect them in series, i.e., wire from one directly to the next,
snd to make all but one single-stroke ends. Bells connected in multiple
•re, M in diagram Ho. M, glye better satisfaction, although requiring more
vixe.
i.i-fi— !
^•9. Three-Line PMtory Call.
A amber of Bells operated by
ttynmnber of pushes. All bells
niog by each push.
£
FiQ. 40. Simple Button, Three-
Line Return Call. One set of
battery.
F
SCMM
Tm> 41. Blsr^e Button, Two>Llne
tDdOrofmdB«tvimCaU. One set
of battery.
&
3*]
Fio. 42. Two-Line Return Call.
Illustrating use of Return Call
Button. Bells ring separately.
294
CONDUCTOBS.
^
t
&
ii!i
Fia. 43. One-Line and Ground Betum
Call. lUuBtrating use of Return Call
Button. Bella ring separately.
Fig 4i. Simple Button, Tv<
Line Return Call. Bella
together.
i
i
Ftg. 46. Simple Button, One-Line
and Ground Return Call. Bells
ring together. The use of com-
plete metallic circuit in place of
ground connection is adylsed in
all cases where expense of wire
is not considerable.
Fig. 46b Four Indication Annunoia-
tor. Connections drawn for tv
buttons only. A burglar alarm dr*
cult is similar to the above, bul
with one extra wire running frmii
door or window-spring side of bat-
tery to burglar alarm in order to
operate continuous ringing attach*
ment.
C^
Fig. 47.
m of connections for control of lights from two points.
)
qhsslJ^
Fig. 48.
Dia^pttm of connections for control of lights from four points. By in-
troducmg other switches like A and B control can be had from any number
of points.
d
M.
^nssassk
Fig. 40. Four Indication Annuncia-
tor, with extra Bell to ring from one
Push only. Illustratii^ use of
threo-point button.
|f\ j^
Fig. 50. Acoustic Telephone with
Maf^neto Bell Return Oall. Ex-
tension Bell at one end of fine.
TRANSTOBMERS.
295
In nnmins lines between any two points, use care to plaoe the battery, if
. iwbkL near the push-button end of the line, as a slight leakage in Uie dr-
enit win not then weaken the battery.
When mat is to be used, throw it into the oircuit
by the twitch, so that when the circuit is closed by a
penon stepping on the mat, the automatic drop will
keep it dosed, and both bells will oontinue to ring
mul the drop is hooked up again.
Fig. 51. Diagram of Burglar-Alarm Mat, two Bells,
Qoe Poeh and Automatic Drop; all operated by one
bstterv. Both bells ring from one push or mat, as
dewed, by changing Uie switch.
Fie. 53. Pendant and Automatic Gas- Fio. 63. Pendant Qas-Iighting Cir-
U^ting Circuit, with Switchboard. cuit, with Switchboard, Relay
and Tdl-Tale BelL
The generators are rated by their volt-ampere capadty and thdr appai
vatu, and not their actual watts, so that the mse has to be increased if
poTO-fsetor of the system is low.
rent
if the
I
WJ[KKli« V^U TltJLlVSFOMMBmS.
For lighting eirrndts using small transformers, the voltage at the prima-
nyol the step-down transformers should be made about 3% higher than the
t^taodagf voltage multiplied by the ratio of transformation, to allow for the
drop in tiansformers. ui large lighting transformers this drop may be as low
M 2%. Standard lighting transformers have a ratio of 10 to 1 or some m\il-
tiple thereof .
For motor drcwts, the voltage at the primaries of step-down transformers
uoold be made about 6% hithte than the secondary voltage multiplied by
we nUo of transformation. Transform<»« used with 1 10 volt motors on any
f^ vnrimn should have a ratio of 4i to 1, 9 to 1, or 18 to 1 respectively
^ 1040, 2060t and 3120 volt generators. The transformer capacity in kilo-
*s8t ihoQld be the same as the motor rating in hone'pawer for medium-sised
potori, sad slis^tly larger for small motors and where only two trans-
"nners are used.
296
CONDUCTOaS.
0»pttcitte« of T
fomi«ni to b«
Iiftdactlon Motoni.
wttM
Kilowatts per TraoBformer.
Size of Motor.
Hone-Power.
Two Transformers.
Three Transformers.
1
.6
.6
2
1.5
1
8
2
1.5
5
3
2
7i
4
3
10
5
4
15
7.5
5
20
10
7.5
30
15
10
50
25
15
75
25
friJEuor« FOR inmjcnoiv hkoxora.
The standard (General Electric) induction motors for three-phase cir-
cuits are wound for 110 volts, 220 volts, and 550 volts; motors of 50 H.P.
and above are, in addition, wound for 1040 volts and 2080 volts. Motors
for the two latter voltages are not built in sizes of less than 50 H.P. Where
the four-wire, three-phase distribution ssrstem is used, motors can also be
wound for 200 volts.
The output of an induction motor varies with the square of the voltas» at
the motor terminals. Thus, if the volts at the terminals happen to be 15%
low, that is, only^ 85% of the rated voltage, a motor, which at the rated volt-
ace gives a maximum of 150% of its rated output, will be able to give at the
l5% lower voltage, only (^)^X 150— 108% of its rated output, and at full
loaia will have no margin left to carry over sudden fluctuations of load while
nmning.
Thus it is of the uftmoBt importance to take care that the volts at the motor
terminals are not below the rated volts, but rather slightly above at no load,
so as not to drop below rated voltage at full-load or over-load.
The output of the motor may be increased by raising the potential; in
this case, however, the current taken is increasecf, especially at light loads.
The direction of rotation of an induction motor on a three-phase circuit
can be reversed by changing any two of the leads to the field.
Like all electrical apparatus, the induction motor works most efficiently
at or near full load, ona its efficiency decreases at light load. Besides this,
when nmning at light load, or no load, the induction motor draws from the
lines a current of about 30% to 36% of the full-load current. This current
does not represent ener<:;y, and is not therefore measured by the recording
watt-meter; it constitutes no waste of power, being merely what is called an
idle or ''wattless" current. If, however, many induction motors are oper*
ated at light loads from a generator, the combined wattless currents of the
motors may represent a considerable part of the rated current of the gene-
rator, and thus the generator will send a considerable current over the line.
This current is wattlecs, and does not do any work, so that in an extreme
case an alternator may run at apparently half-load or nearlv fulMoad cur-
rent, and still the engine driving it nm light. While these idle currents are
in general not objectionable, since they do not represent any waste of
power, they are undesirable when excessive, by increasing the current-heat-
ing of the generator. Therefore it is desirable to keep tlie idle currents in
the BysienL as low as possible, by carefully choosing proper capacities of
motors. These idle currents are a comparatively small per eent ol the total
CONNECTIONS.
29T
■^
eorrent at or near fall-load of the motor, but a larger per cent at light loads.
Therefore care should be taken not to install larger motors than neoessarv
to do the required work, since in this case the motors would have to work
eontinuoualy at light loads, thereby producing a larger per cent of idle cur-
rent in the system than would be produced by motors of proper capacity;
that is, motors running mostly between half-load and full-load.
C«rraat taken l»j
C^nenil Electric Co., Tli:
■ Metors lat UO l^olta.
Starting
Starting
H.P. of Motor.
Full-Load
Current at
Current
Current.
150% of FuU-
Load Torque.
at Full-Load
Torque.
1
6.5
10
2
12
36
3
17
54
5
28
•42-84
28
10
55
70
55
15
80
120
80
20
105
167
105
30
150
252
150
£0
250
400
250
75
370
585
370
100
600
825
500
150
740
1180
740
l^e current taken by motors of higher voltage than 110 will be proportion-
ally leas. The above are average current values, and in particular cases the
▼klosB may vary slightly.
comrsenoiTA oi* oniAirsvoiuiisiis x-os irisiirc}.
The connection of three transformers, with their primaries, to the genera-
tor and their secondaries to the induction motor, m a three-phase system,
are ghovn in Fig. 26. The three transformers are connected with their pri-
mvies between the three lines leading from the generator, and the three
Keondaries are connected to the three lines leading to the motor, in what
ii called delta connection.
Tht connection of two transformers for the supply of an induction motor
(nnn a three-pliase generator is shown in Fig. 56. It is identical with the
^F
ToTOt
Fio. 64.
FlO. 65.
vnngement in Fig. 64, except that one of the transformers is left out, and
ttietTiro other transformers are made correspondingly larger. The copper
f^qidred in any three- wire, three-phase circuit for a given power and loss is
^« u compared with the two-wire, single-phase, or four-wire, two-phase
^tem, haying the same voltage between lines.
* The 5 H.P. motor is made with or without starting^witch.
298
CONDUCTORS.
The connections of three transformers for a low-tension distribution ays*
tern by the foar-wire, three-phase system are shown in Fig. 56. .The thras
transformers have their primariesjoined in delta connection, and their mo-
ondaries in '* Y " connection. The three upper lines are the three main
three-phase lines, and the lowest line Is the common neutral . The differenee
of potential between the main conductor is 200 volts, while that between
either of them and the neutral is 115 volts. 200 volt-motors are joined to the
I
^31
~3i:
s
I
Fio. 66.
Fio. 67.
mains while 116 volt-lamps are connected between the mains and the neutraL
The neutral is similar to the neutral wire in the Edison three-wire system,
and only carries current when the lamp load is unbalanced.
The potential between the main conductors should be used in the formulB,
and the section of neutral wire should be made in the proportion to each of
the main conductors that the lighting load is to the total load. When lights
only are used, the neutral shomd be of the same size as either of the wree
main conductors. The copper then required in a four-wire, three-phase sys-
tem of secondary distribution to transmit a given power at a given loss is
about 33.3 %, as compared with a two-wire, single-phase system, or a fonr-
wire, two-phase system having the same voitage across the lamps.
The connections of two transformers for supplying motors on the four-wire,
two-phase system are shown in Fig. 57. This system practically consists of
two separate single-phase circuits, half the power being transmitted over
each circuit when the load is balanced. The copper required, as compared
with the three-phase system to transmit given power with given loss at the
same voltage between linesi is 133i % — that is, the same as with a single-
phase system.
STANDARD BYMBOLS FOR WIRING PLANS
AS ADOPTED BY THE NATIONAL ELHO-
TRICAL CONTRACTORS ASSOCIATION.
(Copyrighted.)
S{ Celllns Outlet; Electric only. Numeral in center iadioatai
number of Standnrd 16 G.P. Incandescent Lamps.
K^ Celling Outlet; Combination. | indicates i-16 C.P. Standard
Incandescent Lamps and 2 Oas Burners. If gas only ji(
Bracket Outlet ; Electric only. Numeral in center Indieates
number of Standard 16 C.P. incandescent Lamps.
Bracket Outlet ; Combinations. | Indicates 4-16 C.P. Standard
Incandescent Lamps and 2 Qas Burners. If gas only ^^^0i
Wall or Baseboard Beceptacle Outlet. Numeral in center indi-
eates number of Standard 16 C.P. Incandescent Lamps.
^ Floor Outlet. Numeral in center indicates number of Standard
16 C.P. Incandescent Lamps.
i3 S Outlet for Outdoor Standard or Pedestal: Electric only. Numeral
indicates number of Standard 16 CJP. Incandescent Lamps.
tt-f- Outlet for Outdoor Standard or Pedestal ; Combination, t iudi-
** cates 6-16 C.P. Standard Incandescent Lamps ; 6 Qas Burners.
Drop Cord Outlet.
^ One Light Outlet, for Lamp Beo^tacle.
d Arc Lamp Outlet.
ft Special Outlet, for Lighting, Heating and Power Current, as
described in Speciileations.
^^OO Ceiling Fan Outlet.
S^ S. P. Switch Outlet.
S* D. P. Switch Outlet.
S^ 3-Way Switch Outlet.
S* 4-Way Switch Outlet.
3° Automatic Door Switch Outlet.
3^ Electrolier Switch Outlet.
B M«ter Outlet.
^^ Distribution Panel.
^1 Junction or Pull Box.
J^ Motor Outlet ; Numeral in center indicates Horse Power.
Motor Control Outlet.
Transformer.
209
Show as many Symbols as there
are Switches. Or in case of a
very large group of Switches,
indicate number of Switches
by a Roman numeral, thus ;
S^XII; meaning 12 Single Pole
Switches.
Describe Type of Switch tn
Specifications, that is, Flush
or Surface, Push Button or
Snap.
<
300
STANDARD SYMBOLS FOR WIRING PLAKS.
Main or Feeder run concealed
under floor.
Main or Feeder run concealed
under floor above.
""■■■■ Main or Feeder run exposed.
Branch Circuit run concealed
under floor.
Branch Circuit run concealed
under floor above.
Heights of Center of Wall
Outlets (unless otherwise <
specifled):
Livinff Rooms 6 ft. 6 ins.
Chambers 5 ft. 0 ins
Offices 6 ft. 0 ins.
Corridors 6 ft. 3 ins.
Heights of Switches (nnl^
otherwise specdfied) :
4 ft. 0 ias. *
""""*■" Branch Circuit run exposed.
•• — •• Pole Line. ' —
• Riser.
P Telephone Outlet ; Private Service.
J^ Telephone Outlet ; Public Service.
□ Bell Outlet.
O^ Buzzer Outlet.
S2 Push Button Outlet ; Numeral indicates number of Poshes.
"N^ Annunciator ; Numeral indicates number of Points.
-^ Speaking Tube.
— © Watchman Clock Outlet.
— 1 Watchman Station Outlet.
— O Master Time Clock Outlet.
— HD Secondary Time Clock Outlet.
f7l Door Opener.
B Special Outlet ; for Signal Systems, as described in SpeolfloaUons.
l|l|l||||| I Battery Outlet.
{Circuit for Clock. Telephone, Bell or other Service, run under
floor, concealed.
Kind of Service wanted ascertained by Symbol to which line
connects.
(Circuit for Clock, Telephone, Bell or other Servloe. run under
floor above, concealed.
Kind of Service wanted ascertained by Symbol to which line
connects.
UNDBBGBOUND GONDUITa AND
CONSTRUCTION.
Wrb tte Mtablishment of ihs fink eomnMroul Hone teltmph lint
9R»bibly oommcnoM the hiatorv of Um "underground wire" when a.
lokto-fiereha coTered eable wm laid in m tnsoh inade oy an oz-draim plough.
8tavM in the evohition of the preeent "monolithio" conduit are promi-
HBlly marked by the eyttem of croupinc wiiet permanently inetalled and
■eperiled by the pourixue about them in the trenoh of vanoue inwikting
•oa^oaads; by the " buut up ssrttem" made of oraoeoted boards ao plaeed
at to form aqnare <^i*«»w*>i« or dueta; by the **pump log'' ayatem or aquared
timber bored to required aiae and creoaoted; by the oament lined iron pipe
CjaUm; by the uae of imper moulded and treated with dielectric oompounoa;
lad hv the now -very huiely uaad Titrified elay. Olay oonduita ahouki be
manaiaotured from a clay which will vitrify to a hishly homogeneoua and
■oa-afaaoibfait condition and be free ficom chemical elamenta (iron, aulphur,
atCL) wliifili under the action of heat in the kilna reault in nodea or buaten
ia the ware.
There are two eatabliahed atylea of olay conduit commonly deaignated aa
"ncia duet" and "multiple duct." The atandard unit of the einale duet
ii of aquaie eroea aection meaennniB 4^' by 4}" with oomen ohanueredt ia
18 inebea in len^pth, and hae a 3| moh round core or hole. The atandard
■aWple duet umte an of two, three, four, or aiz duct aectiona, the bore of
each duct of any aection bein|; aquare and meaauilinj 3i bv 3}, the interior
and exterior wall being f " thick; the lengtha of unite are, for two and three
duet. M incfaea. and for four or aix duet 86 inobea. The demand for 3i inch
aad 4 inch boree or even larger ia oonatantly increaaing. Multiple duct
eooduit of nine duct and twelve. duct aecticma have been offered to the
Inde but ao far have not come into extenaive uae.
Siagle duct eonduita being mora flexible are better adapted to uae whera
MTriee pipee, eurvea, or ofaetaelaa ara frequently encountered. Laid with
bvofcea jomta the poaaibility of the heat from a burning cable, being oomf
■mirateH to a neighboring cable, ia precluded. Where hi^ conatruotion
OB a email baae (two dueta wide by more than five ducta high) ia required,
•mdea ara not used to advantage. A maaon ehould, under fair working
eoadttiona, average in a day of eiight houn from twelve hundred to aixteen
handred duet feet of aingle duet conduit.
Muhiplca have in thair frivor fewer joiata, ai eater weight per unit, and the a
JMt tbat their installation requirea only unaJdUed labor. Two men aelected M
mm a gang of laborera will lay from eighteen hundred to twenty-four hun- ■
dred duet leet per day of ten boura. 1
Tkroo^ town or city atreeta the conduit ehould have a foundation of
•PBcreie at leaat 3 indiea thick. Whera fre9uent excavationa for other
eorke are probable a complete encaaement of 3 mchea to 4 inchee of concrete
•honld be placed on both eidee and on top of the ducta. The aide protec-
tion is, however, aometimea omitted and creoaoted boarda aubatituted for
amerete on top. The top covering over ducta ehould be not leee than 24
iaehea below the aurface of the atreet.
Tk» aaverml comdmlt torme ara generally defined aa followa:
The word "Conduit" meana the Mgregation of a number of hollow
tebee of duet material and indudee aUof the ducta in a croee eeetion of
Ike eubway. In general a conduit will conaiat of four ducta or mora.
The woid "Duet" meana a aingle continuoua paaaageway between man*
Bolee or through any portion of the conduit or laterals.
The word 'llanhole" meana an underground chamber built to raeeive
ilactrioal equipment and auitable to give acoeea to the conduit.
The word 'Service Box" meana an underground chamber eimilar to a
■aahoU but of emaller aiae, and deaigned primarily to give acceae to dia-
triboting eondttctora.
801
302
UNDERGROUND CONDUITS.
Hm word "Lateral" meant one or more dueta extending from a maahole
or eerrice box or from one or more of the main conduit oucte to aome dii-
tributing point. In general Jaterala will oonsist of one or two ducts few the
■ame service connections. One or more laterab may be installed in the
same trench. .
Manholes Vary >o much according to the ideas of the diffennt ensineera
that it is' difficGUt to give data that would suit all of them. However, the
average sise of manhole is 5' X 6' X 6' in the clear with a 12f waU. The
covers for same vary from 800 to 1400 lbs. The general practice is to
have vmtilated covers and sewer connections with automatic badc-watsr
trans.
The Servioe Boxes are made generally of concrete with an 8' wail, either
S' X 2^ or 2' X 3' in len^^h and width, and extending in most eases to the
top \tkyet of the conduit system, which would make the depth of tfas
servioe boxes vary according to the depth of the conduit system proper,
the upj;>er tier of duets being used for distribution. Covers for servioe bo3
inchidmg inside pan, weigh from 400 to 600 lbs.
Us«al Prftctloe of CoMdnlt fTork.
Manhole walls, where built of concrete are generally 8 to 12 inches tfaiek,
made of Portland Cement concrete, using, 1^ inch stone, mixed in the pro-
portion of an 1-2-5 and in some iiutances as high as 1-3-8. While in some
cases the conduits proper are surrounded with Portland Cement oonorete,
the usual ^actios throughout the countrv is with casing of hydraulio
eoncrete m a 1-2-6 mixture, stone f inches to 1 inch.
Tlie Cost of CoMdoits.
(A. v. Abbot in Eledrical World <md Enginmr.)
The items of cost of conduit construction are:
1. Duct material. 2. Pavement per square yard. 3. Street
tion per cubic foot, including the removal of paving, the refilhnent of the
excavation sJFter the ducts are laid, and the tonporary replacement of the
paving. 4. Concrete deposited in place. 6. Linbor of placing duct ma-
terial 6. Engineering expenses. 7. Manholes. 8. Removal of obstadsi-
TASXiB ITo. 1.
Cost of H»aliolos In I»oll»ra.
A, Briei with Brick Roqf,
Bate (Dollars).
Item.
Amount.
Min.
Amt.
Per
Ct.
Av.
Am.
Per
Ct.
Max.
Amt.
Per
Ct.
Min.
Ave.
Max.
1
12.6
$
11.26
S
Excavation
376 cu. ft
.02
.03
.04
7.60
11.8
15.00
11.2
Concrete .
.7 yard
2200
6.00
7.00
9.00
3.60
6.9
4.90
6.3
6.O0I
4.4
Brick . .
12.00
16.00
18.00
28.40
44.6
33.00
35.3
39.60
294
Covsor . .
1
6.00
10.00
16.00
6.00
8.4
10.00
10.6
16.00
11.2
Iron . . .
500 lbs.
.016
.03
.06
7J60
12.6
liJOO
16.1
26.00
18.6
Repaving .
6 vards
.76
2.00
4.00
4.50
7.6
16.00
12.8
24.00
17.3
Cleaning .
10 loads
JSO
.76
1.00
5.00
8.2
100.0
7J50
93.66
8.1
10.00
7.4
Totals . .
. • • .
m «
• •
■ •
60.40
100.0
134.00
100.0
COST OF UMOERaROirND CONDUITS.
303
B. Brick with Qmcrtte Ro4tf.
Item.
Amoimt.
Bate (Dollars)
Per Unit.
Min.
Amt.
$
Per
Ct.
14.8
18.7
37.8
9.0
8.9
9.9
At.
Am.
•
Per
Ct.
Max.
Amt.
•
Per
Min.
ATe.
Max.
Ct.
ExetTation
CoDcrete .
Bilek . .
Corer . .
Bspavlng .
375 on. ft.
1.9 yards
lOOO
1
6 yards
10 loads
.02
6.00
12.00
5.00
.75
.60
.08
16.00
10.00
2.00
.75
.04
9.00
18.00
16.00
4.00
1.00
7.60
9JS0
19.20
5.00
4JS0
5.00
11.96
13.80
24.00
10.00
12.00
7.60
14^
17.0
aos
12.8
16.4
9.5
100.0
15.00
17.10
28.80
15.00
24.00
10.00
18.8
15.7
95.7
13.8
21.9
9.1
ToUb . .
. • • .
• ■
• •
• .
60.70
1004)
78.06
100.90
IOOjO
C
Ctmerete, Manhole,
Itsm.
Amount.
Bate (Dollars)
Per Unit.
Min.
Amt.
f
Per
Ct.
16.8
60.6
11.2
10.2
11.2
100.0
At.
Am.
•
11.25
31.60
10.00
12.00
7JJ0
72.26
Per
Ct.
15.6
43.6
13.9
16.6
10.4
100.0
Max.
Amt.
•
Per
Min.
Are.
Max.
Ct.
KxesTation
Goocrete .
Cow . .
BcpsTing .
375 en. ft.
4J> yards
6 yards
10 loads
.02
BM>
6.00
.75
M
7.00
10.00
2X0
.75
.04
9.00
15.00
4.00
1.00
7.60
22M
5.00
4JM)
5J0O
16.00
40.60
16.00
24.00
10.00
14.8
38.8
14.4
23.0
9A
Totals . .
....
. .
• ■
. .
44 JO
104UI0
lOOX)
Wl>enevcr praetioable, a sewer connection to each manhole is desirable
to provide exit for street drainage. Such sewer connections are essential
is sli esses wfaAre manholes are equipped with Tmtilating covers, otherwise
the insnboles will fill durins every storm.
Gm8 ef Saw
•r G*«M«cti«Ba IH Dollan.
Bate (Dollars)
Itsra.
Amonnt.
Per Unit.
Min.
PAr
Ave.
Per
Ct.
Max.
Per
,
Amt.
ct.
Am.
Amt.
Ct.
Min.
Ave.
.03
Max.
.04
$
•
1
SsesTstion
826 ca. ft.
.02
4 60
36.1
6.76
26.0
9.00
21.4
Oooerete .
6 yards
.76
2.00
4.00
3.76
29.2
10 00
38.8
20 00
47 0
^ •
1
1.00
2.60
4.00
1.00
7.6
2 60
19.6
4 00
9 3
Oorer . .
16 feet
.04
.07
.10
.64
6.0
1.12
4 4
1 60
3.6
Beparlng .
2 loads
.60
.76
1.00
1.00
7.6
1 60
6.8
2.00
4.7
QssBlng .
1
9.00
4.00
6.00
2.00
15.6
4.00
15.4
6.00
14.0
Totals. .
. • •
• .
• •
•
12.89
100.0
25.87
100 0
42.60
100.0
(
304
UNDERGROUND CONDUITS.
Bianholee win occur at intervals of from 250 to 6(X) feet,
the constant cost per conduit foot for this item is obtained by dividilQg tlw
various manhole costs by the distances between them.
VAsxa no. s.
€)mmtitmmt Coet p«r CondaiC Foot for Mfuiholoa Ui Dolli
Distance between Manholes in Feet.
260
300
860
400
600
Brick manhole with
brick roof . . .
Min.
Are.
Max.
.238
.872
.636
.196
.310
.427
.170
.248
.384
.148
.236
.336
.118
.186
.268
Brick manhole with
brick roof . . .
(Min.
{Ave.
(Max.
.203
.300
.440
.168
.260
.363
.146
.223
.314
.127
.196
.272
.102
.166
.218
Concrete manhole .
Min.
Ave.
Max.
.176
.278
.416
.148
.242
.347
.127
.200
.298
.111
.180
.260
.069
.144
.206
Sewer connection
(Min.
{Ave.
(Max.
.061
.104
.170
.043
.086
.142
.038
.074
.121
.082
.064
.106
.025
.061
.064
Engineering expense will vary from a minimum of 5 cents per oonduii
foot to a maximum of 12 cents, depending chiefly upon the difficulty of
the worlc
The cost of the removal of obstacles is an item impracticable to estimate
a priori with any degree of certainty, as it is imposdUe to foresee, and
usually impracticable to ascertain, even with the greatest care, the impedi-
ments to be encountered beneath street surface. Experience indicates
that this expense will vary for small subways from 10 cents to 62 oente per
foot of conduit; for medium-sized ones from 12 cents to $1.10, and for
large conduits from 15 cents to $2.25.
The cost of paving is partially dependent upon the number of duets.
It is impracticable for workmen to perform their avocations in a trench
less than 18 inches wide, and, therefore, a strip of pavement of this width
must be opened irrespective of the number of ducts to be installed.
The cost of repaving will further vary with the kind of paving. In
Table No. 4, the usual kinds of pavement encountered, the minimum,
average, and maximum prices per square yard, and cost per conduit foot
are given.
Allowing a disturbance of paving for six inches on each side of the trench,
the cost per lineal foot for small conduits will varv from 2.3 to 26.3 cents;
for medium-sized ones from 4.6 to 29.2 cents, and for large conduits from
6.0 to 35.0 cents.
Similarly the cost of excavation is only partially dependent upon the
number of ducts.
^
COST OJ" PAVING.
306
i
a
I
I
h
I
1
e
8
I
t
I
5jH
§
-81
?
l.i
I
■31
6«
§
SSI"
I
P4
S>188858S8
CO
' s
s
S 8 S 8 8 » ^.
eO M 99 pm ci ^
S1i§§S§§S
OQ
§1§iS|g§§
Of
• «■
!^ ^ 8 8 8
c« ei ^ * iH i^'
8 S f^
S*". §§§ISi§
9
§»: §§§§Hi§
■ Jf
cr •••••• •
IS SS 8 8 8 8 S
•ii e<i ^' ' ^
I
8
I •§ -S
11-
•a t ""
« ■ H <D ^ 9
^ ^ O O « H
(
306
UNDERGROUND CONDUITS.
Ezperienoe shows that 3 feet 6 inches is a miniroynn pennisnble deptb
for the bottom of subway oonstruotion, and that the cost of street excava-
tion will vary from two to four cents per cubic foot of material excavated,
including the removal of the pavement, the refillment of the trench, aod
the replacement of temporary paving. The cost of excavation will, Uwe-
fore, stand as in Table No. 1.
Coat of Atreot M^mrnvwiUmm per CoMdvit Foot Ib Doll
Minimum
.02
per Cu. Ft.
Average
.08
per Cu. Ft.
Maximim
.04
perCn. Ft.
1 to 9 ducts . . .
10 to 16 ducts . . .
17 to 26 ducts . . .
.106
.160
.226
.1075
.MO
.8876
.210
.830
.460
Table No. 5 summarises these constant items; for oondmts of frook one
to nine ducts, ten to sixteen ducts, and seventeen to twoity-five doflks^
giving the minimum, average, and maximum prices of all, together with
the percentage that each bears to the total.
Table No. 6 enumerates the probable prices for the varioua forms of
duct material laid into place, calculated in a manner similar to the precsd-
ing tables, including a percentage column showing the effect of eara item
upon the total expense.
CoMatMit Coat per
COO«B
It Foot te Dollars.
•
Minimum.
Average.
Maximum.
Item.
Cost.
Per
Cent.
Cost.
Per
Cent.
Cost.
Per
Cent
1 to 9 ducts.
Excavation ....
Paving
.106
.0696
32.6
21.2
15.2
32.0
100.0
88.6
20.2
12.1
29.1
.1576
.185
.06
.25
23.4
27.5
11.9
37.2
.210
.279
.12
1.00
13.0
17.4
Engineering ....
Removal of obstacles .
.06
.10
7.6
es.i
Total
.3245
.6725
.24
.222
.06
.28
100.0
29.1
27.0
9.8
34.1
1.609
.82
.3318
.12
1.10
100.0
10 to 16 ducto.
Excavation ....
Paving
.16
.0645
17.0
17.7
Engineering ....
Removal of obstacles .
.06
.12
6.6
6S.8
Total
.4145
100.0
43.0
18.6
9.6
28.8
.822
.3875
.26
.08
.35
100.0
82.8
26.3
7.8
34.1
1.8715
.46
.63
.12
1.26
100.0
17 to 25 ducts.
Excavation ....
Paving
Engineering ....
Removal of obstacles .
.226
.0970
.06
.15
19.2
28.2
6.1
58.6
Total
.522
100.0
1.0276
100.0
2.34
100.0
^
COST or UNDERGROUND CONDUITS.
307
From the data thus ooUeeted, the total cost of a conduit of any riie is
readily determined by taking first the cost per foot of street for manholes
and sewer eonnections; second, the cost of the constant street items as
given in Table No. 6 depending upon the number of duets, aiKl third,
the ciotX pet duct foot determined from Table No. 6 multiplied bjr the
number of ducts to be laid, and adding these three items together, giving
immediatdy the total cost per conduit foot.
Coat of Sact Hat«rlal
TABIDS Ma. V.
te Place IM Oollara.
Minimum.
Average.
Maximum.
Item.
Cost.
Per
Gent.
Cost.
Per
Cent.
Ck)st.
Per
Cent.
Hollow brick.
1>aet material . . .
PkMing
.02
.006
44.4
11.2
44.4
.035
.01
.06
36.8
10.5
52.7
.06
.015
.06
34.5
10 3
Enctsement ....
.02
56.2
Total
.046
100.0
67.6
2.2
30.3
.006
.06
.0026
.0475
100.0
60.0
2.5
47.5
100.0
53.6
3,4
43.0
.146
.066
.004
.07
100 0
Multiple duel.
Doet material . . .
Plsdng
.036
.011
46.7
2 9
Eneasonent ....
.015
50.4
Total
.061
100.0
62.5
3.2
34.3
.10
.06
.004
.06
.138
.08
.006
.068
100 0
OeiBeat-llned pipe.
Cement pipe.
Wood pulp.
Dnct material . . .
Placing
.04
.002
48.2
3 6
BDcasement ....
.022
48.2
Total
.064
100.0
98.04
1.96
0.00
.114
.95
.0015
.00
100.0
98.0
3.0
0.0
.174
.06
.003
.00
100 0
Creosoted wood.
Duct material . . .
Placing
.04
.0006
96.0
5 0
Eoeasement ....
.00
0.0
Total
.0406
100.00
.0615
100.0
.063
100.0
Cloa* per Conduit Foot ta Cltloa.
GoBtper
Trench Foot.
Number of Ducts.
2
4
6
12
16
$2.76
2.76
2.82
3.13
2.78
2.91
20
24
AtlanU . . .
Louisville . .
Cfaieinnati . .
Boston . . .
Springfield . .
Brooklyn . .
$.88
.89
.92
1.06
.90
.96
$1.14
1.12
1.18
1.34
1.16
1.21
$1.43
1.40
1.48
1.65
1.45
1.51
$2.31
2.29
2.36
2.66
2.34
2.45
$3.22
3.19
3.26
3.66
3.24
3.39
$3.53
3.63
3.72
4.10
3.68
3.84
(
r
308
UNDERGROUND CONDUITS.
m o
1 •
iCKI^flOO
a I S i S 8
s
I
t
9
I
9
!
I-^I
at I g g 8 I"
to
8. S9 ^siisi^SsS::
i S "'^ ' ^ ^ ^ I
gS8 SSCiS, 88 ^9
iS(i«»a
fr
^*»|
^ Q
S Ss Ssi^isls^sis S89 88 S8
g '^S si S § 55 g §9*8'- •s^
So §9 S8i»88g8i88? 9S3S 88 S^
§ g ^^5; s e a
5* i
9 J8s SBialsagSsie wa sg s
a -3 a SB I g
e*
^s«a»- «B«
J ft
S S^S l8§»§^§8§Sigl S38S 88 ^&
fWl«fc« '^IQ*^
§ §
9 S t: - 8
2^
8 g s •• g
S
t»t« •<<
S
to
a
s
.•a
' o
•w
S 5J «^^5»iSts5^«| til?
OHOHOHOHUHOH OHO
S
^
HO
2.
•I ' -a
.&
••d
•d
* 'a
fl
4f.d
a •2'-*
•a
e<8
|S
^_ -||^ r^ ^-
'8.
m
•'O
3
I
O
.4
Za
t
•3
§
&
^1
«
3
9
3
0
A
a
a
M
P
1
e
0
a
.8
9
Ok
►
^S^Z!!^;::? l: '» «°U mu.t«(iij(; ae pr«ilce of the Boitoii KdUon
W NBi oc muuiolea mud otcondulu. ——».■«■)( iwiu-
1
noi. Suidt. HubolM.
310 UNDBRGS
^
WiM
Fio. E>. Plan and
Fro. e. Pm
i
MMA-^-A
Wl*
Hf\
r*Ti .■
^flilft
1
1
Fia. T. Tmufornier Huiliola.
312
UNDERGROUND CONDUITS.
Street Ljvl
Fza« 8.
Fio. 9. Gest'B Patent Manhole Deslgni.
i
•to. 10. Sootlon*! Vleir of Mmholo Coxers,
r
314
UNDEBQROUND CONDUITS.
INNER COVER
8ld9
/^yvv/^v^\vy\^Y/\v^vv/v^^^
<
aosQDsaa
aosoasaa
aasunsafls
UOSQQ
oil
aasoDSQO
m
QDSDasQa
I
7
STREET COVER
Fig. 11a. Manhole Corers.
TIGHT COVER FOB MANHOLE. 815
i
316
UNDERGROUND CONDUITS.
li«mls«« Gm« of G««di«tt.
W. P. HAirCOCK, BOBTOK Edisok Gokpaitt.
Material and Labor.
Material.
Lumbor at $16.00 per M., or .016 cents per
square foot, B. M
Concrete at 94.86 per cubic yard, or 18 cents
per cubic foot
Mortar at $3.98 per cubic yard, or 14 cents
per cubic foot
Ducts laid down beside the trench at $.0602
per duct foot
Labor.
Bzoarate and backfill at 16 cents per hour
or 9.0278 per cubic foot
Cut and place lumber at 20 cents per hour,
or 9>0006 per square foot B. M
Mix and place concrete at 16 cents per
hour, or $.0222 per cubic foot ....
Mix andplace mortar at 26 cents per hour,
or 9.0026 per cubic foot
Lay the dnots at 60 cents per hour, or 9*0040
per duct foot
Haul away the dirt at 60 cents per hour, or
9*0142 per cubic foot
Paye the trench at 91.44 per square yard,
or 9.16 per sauare foot
Cost of manholes per duct foot
_ Total cost of manhol^ __ 490.28
"~ Total number of duct feet ~" 22,200
Inspection at 60 cents per hour, or 9'0033
per duct foot
Engineering expenses at 9.0214 per duct
foot
Incidental expense at 6 per cent of
total
Cost
per Duct
Foot.
9
.0106
.0231
.0026
.0602
Cost per
Conduit
Foot.
Total
Expense.
9
.1676
.0390
.7630
.0206
.0004
.0029
.0016
.0040
.0047
.0600
.0221
.0033
.0214
.0116
9.2350
.0060
.0436
.0240
.0600
.0706
.7600
.8316
.0486
.8210
.1740
93.6260
Total
Coat for
Itomfbr
the Total
Une.
9
.10
614.16
68.90
1U4.4I
9.31
6S.48
37.09
88.00
104.7S
1109.S8
400.28
73.26
476.08
948.22
96218.78
Camt of 5' X *' X »' MaMliol*.
W. P. Hancock, Boston Edison Compakt.
28.76 cubic feet concrete, cost in place 9.202 per foot 9J.2
2,500 hard sower bricks, cost $9.00 per M ».W
If S. 6' trap and connections cost 5.W
30' 6' Akron newer pipe, cost 30 cents per foot. . . . . • ,. ... 9.W
R. R. steel (60 lbs. to the yard), 8 pieces 6' 4' k>ng (1013 Iba)
cost 9.0126 per lb IJg
H yards mortar, cost per yard 93.08 •••••• *•:!
1 manhole frame and cover, 962 lbs., cost 9.016 lb H.w
973.50
COST OF UANHOLBS.
317
We Shan need labor that will ooet^ follows:
Bxeavate and backfill part of same, ineludinc that for eewer
oonneetiona, 785 cubio feet, cost $.0378 per foot $21.82
RtfDovB from street 304 cubio feet of dirt, coat 50 centa double
load or $.0142 per foot
Fa;ve 11.08 yarda (includins nuuihole and sewer oonnection),
ooet $1.44 per yard
B. 10 hours, cost 40 cents per hour
n helpers, 10 hours eaoh— 20 hours, cost 15 cents per hour,
1
S
4.30
16.05
4.00
8.00
$40.07
Total cost 1 manhole, complete . $122.57
€:••$ •€ JDmdmwgrammA Cmidiitts la Cklcagv.
G. B. Springer, civil engineer of Chicago Edison Co., says:
The differenoe in local conditions, variations in cost of material and labor,
make it very difi&cult to give a set of figures which will hold good in many
places or in fact in the same place under different drcumstancss.
The following table, however, is submitted as a guide in i4>proximating
the eoet of work of this oharacter as a result of conduit construction cov-
ering ten years in Chicago. The cost of manholes is not included in this
table, but is given in the one following.
Ti*le r^r
■sati^ Coat 9i CoMdvlt, P»r !»««< Wmmt^ ii
Kinds of Pavement
Number of Ducts.
2
4
$.18
.21
.22
.24
.31
.43
6
$.18
.20
.21
.23
.28
.37
9
$.18
.20
.20
.21
.24
.31
12
16
20
$.18
.19
.19
.20
.22
.24
25
30
No pavement
Mai'imfif^t^ . . a . . . • .
Cedar
Cedar i sen we and granite •
Graaite reserve
A^halt and brick reserve .
$.18
.24
.26
.31
.43
.68
$.18
.19
.20
.21
.24
.29
$.18
.19
.19
.20
.23
.26
$.18
.19
.19
.20
.21
.24
$.18
.19
.19
.19
.21
.23
The foUowinfl^ table contains approximate figures based on conditions
pKvailing in Chicago, and may be used as a guide in estimating the cost of
eonduit construction in connection with the table preceding.
Valblefor
V«tal Coat of Manholoa Im IMlToroMt
Kinds of Pavement.
Sise of Manholes
in Feet.
3X3
$41
42
43
44
46
50
3X4
$47
48
49
50
53
58
4X4
4X5
5X5
$109
111
112
113
117
126
6X6
$133
135
136
138
144
156
6X7
$142
146
146
149
155
168
7X7
$160
163
164
167
174
188
8X8
$189
193
194
198
207
224
9X9
No pavement ....
Crfar
Cedar reserve
and granite ....
Granite reaerve . . .
Asphalt and brick
$53
55
56
57
60
67
$64
66
67
68
72
80
$222
226
227
231
243
264
The above figures are based on the same prices for repaving, labor, brick-
layers, cement and sand, as given in the table for conduit, and upon the
loflowing unit prices:
Brick work including labor and material .... $12.50 per cu. yd.
Conerete tope and bottoms $7.50 per cu. yd.
Back water gates $6.50 each.
Bewer grates 30 cents each.
Sewer connections $12.50 each.
8?*f ?"»*■ • ■ .• $5.50 each.
Manhrwe frames and covers
$15.00 each.
UNDERaROUND CONDUITS,
H. W. BnCE IN Electric Club Journal, An
Attcotlon U tailed (a the oroupinc of duoti uid oona
OrdiDuily ducU an bunched U«ether uid broucht
the numhole, w sbown in Fig. 12. Hen tbe <»blei di
one aide and bkU oD the otber aide of tbn manhole.
manboJe inUb, Thu deBgn u objectionable lor a
MBaracked
Fra. 12. Ordinarj' Type at Ifauhola.
onduit to dann^ trom Aart-«ircotl
-„,^ in doee [Hx>xinuty to each other.
I bendinc every cable •faarply M pdnta A and B
i™i;
DNDEBOROUND CABLES.
no. 15. HaalKita OaaMraatian of
■ in tha tood\
s "tr Lj"ti''i
Uihi in tha »i
K>dtd«n tha a
La pU« vh«
{kninElc 15
dunaeed by ■hort-drcuit *t wiy time. In
■trufiit through th» muihoJe vitbout bfiud-
r thg ■urtun of tha Kraund tha ooturtructioD
VmiBBClMOIJirD CABl
JMlM Kt placad audi
DdarKTOi
dmring
recent wai*. cbleC
tTpe of the aolld ijitsnu 1« that In vLlcb the condncCon, properly
"nd lead aorared and proteeted bjr armor, are laid directly In the
. pluk that haa been videly adopted In Bnrope-
^BrawlK^lB" Phua la Uia one Bowir
mtry. Thli plan ntfliiea the manholi ...._ .
Ttia eablea are dnTn Into the dneti from manhole
' ~ ipe that baa bean prevjoiulv drava through tt
■'^roddlng." Boddlng conaliita of acrewInK one -. -■
— — manhole and pnahlng Ihein throogb the duct ontil the
— end la mcfaed. The rope is atlaehed to thelwt rod and the rods
vitbdravn from the dneti bringing the rope irltb them, Sometlmealn
« rf ™i. . ««r ..—1 -i_ i, pngied through the docta. Tha lopa I*
' Boddlng
be r
ii»» rtroda'V 'ia« "iteai'*wlre
■at generallT adopted
le duct by a
i
r
320 UNDERGROUND CONDUITS.
attached to the cable by a mechanical deTice which securely gripe the i
of the cable.
Various means of drawing the cables into the dncts are arailed
depending somewhat on the sise of the cable and the length of the
hand power, man power with windlass, horses, electric motors and
eurines being thus employed.
Types of VnAergTOiuid Cables. —The type of cable employed J
nndergronnd service varies largely with the reaoirements. VirtnaUy
nndergronnd cables are lead covered to prevent Injury to the insulatioBl
moisture, gases, etc. For telephone purposes, lead covered, dry j
insulated cables are universally used, to obtain low static capacity,
pases 180 and 188.} For telegraph purposes rubber Insulation (see pagej
and oil saturated cotton or paper are utilised, as in the telegrl^ph serriflej
static capacity is not of so much importance, but still cannot always *
disregarded, especially in high speed telegraph signaling. The eonduo'
commonly usea in underground telegraph cable Is No. 14 B. ft S. eopi
having a conductivity of 98 per cent. In the case of cotton fiber or pap
cable, each conductor is insulated to six thirty-eeoouds (A) of an ii
outside diameter. The insulating material is thoroughly <med and V
saturated with an insulating oil or compound.
for JBlectrIc MAgl^t and Power purposes rubber, paper
varnished cambric insulation are largely used. (See pp. 174 and 180^ O
to its high cost, rubber cables are not now in as high demand as ionn<
especiaUy as oil saturated paper cables appear to be quite as d
efficient and reliable as ruboer Insulation for high potential work.
It was formerly the practice to place as many as six lead covered el'
liffht cables in one duct, but experience demonstrated that this wss
advisable owing to the difficulty In withdrawing when necessary one
more cables from the duct without injury to the remaining cables. A baisj
out In one cable also frequently injured adioininff oaoles in the dsctj
Present practice favors having onlv one cable in eacn duct, although tiun
may be several conductors within the lead covering. (See page 185.)
To prevent burning of light and power cables due to short circuits in ttl
manholes and other ulaces where the cables are bunched, the cables art
frequentlv covered with asbestos strips about 3 inches wide and A la#
thick, well impregnated with a solution of silicate of soda which aofltt
hardens over the lead. The lead covers of cables carrying altemstial
currents of high amperacre and low E. M. F. should be bonded or careiw
insulated in the manholes to prevent sparking and possible conseqiNii
damage, due to Induced currents In the lead cover of the cables.
All lead covered cables used on high potential circuits should be prs*
tected from damage by static discharge by flared ends or bells, that Ir, W
enlargement of the lead sheath to fully twice the diameter of the lead if^
the cable, for a distance of about a foot. The bell should then be T*
with some good insulating material like Ghatterton (Compound, the
ductor ends, in case of multiple conductor cable, being carefully separ
Cable Heads. — To prevent the entrance of moisture to the ends
telegraph and telephone paper cables the conductors of a short lenm
(about two feet) of rubber covered cable are spliced to those of the P*PV
cable. These splices are then Insulated. A lead sleeve is passed over tti
rubber insulated conductors and the lead casing of the paper cable to vhM
it is then soldered. The outer terminal of the rubber cable is led lutol
metal box or head to which the lead sleeve is soldered. The free condneMMj
are solidly connected to insulated binding posts on the inside of tiie
which binding posts extend to the outside of the head, thus slving sees
to the conductors externally. The sleeve and box are then filled wila
melted rubber compound, the temperature of which must be below tbat
which the rubber insulation will soften ; otherwiso the rubber will
seriously damaged.
^
CABLE TESTING.
BBYUW) BY Wm. Mavxb, Jb.
The majority of the methods of tests and measurements glFen herein are
')le to a<$rlal, underground, and submarine cables.
l||»Ueab]
Blrect lleflectlom Method, w14b Mirror C^alvanoBsotor. ~
SUi method, Fig. 1, is generally used in this country in underground and
Mbmvine vork.
CASLt
FlO. 1.
s and 6= leads.
G=galTanometer, Thomson or D'Arsonral, mirror type.
8zz ihonU for O, osnally A, ,1,, r^.
£= battery, 20, 60, or 100 chloriae silyer cells.
R=z resistance box of megohm or more.
BK= battery reyersing kejr.
Af =short-clrcnit key for O.
Vbtt eoanect a to lower contact point of SK, and take constant of O,
Mriag xiu shunt, and small number of cells, say 6 (depending upon the sen-
■mieM of €f)t vlth standard resistance J7 only in circuit, b being discon-
Medssihown. If 6 cells aroused in taking constant, and 100 cells are
obevedfortest,
fi«n.».«ft - G deflec. X shunt x i? X «)_ „,^. ^.
Constant = i^ooo,00O = megohms.
L jj^'^ obtaining the constant, measure insulation resistance of lead &. by
' ]"Bi]ig it insteadcf SK to a« disconnecting the far end of b from the caole.
jwwwlt ihonld be infinity ; but if not, deduct this deflection from the
;• MBction to be obtained in testing the cable proper. Now connect the far
uS|>ff & to the conductor of the cable, the far terminal of latter being free.
2*Bop«a^ir carefully, and observe if there are any earth currents from
; y csSle. If any, note deflection due to the same, and deduct from bat-
.JJ'TJMdiiigif in the same direction, or add to it if in opposite direction.
«m«lreiA 0 with 8K, and close one knob of BK^ using, say, the ^ shunt.
*pff * few seconds open SK; if spot goes off the scale, use a higher shunt.
!> Mfleetion is low, use a lower snunt. After one minute's electriflcation,
Bote the deflection. The result may be worked out from this reading, but
Qe current should be kept on for three or five minutes longer, and rcMlings
wen at end of each mninte. The deflection should decrease gradually.
At the end of the last minute of test, open BK, and allow the cable to
821
{
322
CABLE TESTING.
discharge fully. Then oloee SK and prees the other knob of BK, roTem*
Ing the battery. After a few moments, open SK, and take readings of dellefr^
tions as before.
The insolation resistance in megohms =" ^°* ,
o X o
where d is the deflection at a given time, and S is the shunt used. If no
shunt is used, x >«
constant
Note that in the aboye constant, the ordinary constant is multiplied bjSQ
for the reason that the battery is Increased 20-fold, or 6 :: 100. In ease tiie
same battery is used for testing as for obtaining the constant, then
G deflec. X S X li
constant
1,000,000
InavlaMaC Cable EnAs for Teato.— Much care must be employed
in order to insure accurate results.in measuring insulation resistance. The
ends should be well cleaned and thoroughly dried. For this purpoae they
are sometimes immersed in boiling paraffin for a few seconds ; or the
ends may be dried by the careful application of heat from an alcohol lamp.
If there be no earth currents, the readings with opposite poles of battevr
to the cable should not varv appreciably at any j^yen minute. Pronooneed
yariation between the readings at given times and unsteady deflections Indi-
cate defective cable.
Ijnavlattoa ]ieaiatauic« by Method of
of Chaive«
The insulation reslstuioe of a cable or other conductor having considera-
ble capacity may be measured by its loss of charge. Iiet one end of the
conductor be insulated, and the other end attached to an electrometer, in
the manner shown in Fio. 2.
Fio. 2.
Let J7 := Insulation resistance in megohms per mile.
C= Capacity in microfarads per mile.
E r= potential of cable as chained.
e = potential of cable after a certain time.
Depress one knob of key iC, and throw key K' to the right, and chuge the
cable for one minute ; then throw key K' to the left, thus connecting the
cable to the electrometer. Note the deflection J7. Noting the movement <4
the spot for one minute, take reading e at end of minutCi then
J?=
26.06
Clogf
If an electrometer is not conveniently at hand, use a reflecting galvanom-
eter, and after charging cable as before, take an instantaneous nlBchargg.
noting deflection E due thereto. Becharge cable as before, then open JT
and at end of one minute, the galvanometer having been disconnectea from
cable in the meantime, take another discharge-reading of cable, and ^pply
CABUD8.
323
the SUM formola m before. If a condenser of low eapaeity be Inserted be-
tween P and thegalyanometer, the latter need not be dlseonnected. The
adTantage of the use of the electrometer is that the actual loss of potential
of the cable may be obserred as it progresses.
VMttar Y^iBte It Cable* b J Claric's KetkadL
In the flgnre (FlG. 3) the letters refer to the parts as follows :
=rB
Fio. 3.
0 li a high-reelstanoe mirror galvanometer.
Aitthediant.
^ ii the shortHsircnlt key. It may be on the sbnnt box or sepaimte.
Xr U a reversing key.
Ju/ii a discharge key.
B iba battery, nanally 100 eella chloride of silrer.
Ch s ) microfarad standard condenser.
The jmnt to be tested Is placed in a weU-insulated trough, nearly filled
vlth lalt water. A copper plate attached to the lead wire is placed in the
vtter to ensure a good connection with the liquid. The connections are
ottdeat shown in the figure, one end of the cable being free. To make test
ekMX^/forahalf minute; then release it^rst depressing one knob of
^ ^#)f (herebv dischazwing the condenser C, through the galvanometer,
vA note the denectlon, if any. A perfect piece of cable of the same length
at the Joint is then placed In the vessel, and if the results with the joint are
praetieally equal to those obtained with the perfect cable, the joint is passed,
wboi the direction is very low, it is evident that the joint is sound, and it
Bay then be considered nnneoessary to compare it with the piece of cable,
it ii Twy important that the trough and apparatus be thoroughly insulated.
' Ketlaod. — This method possesses the advantase that
it dispenses with a condenser, and thereby avoids possible misleading re*
ralti doe to electric absorption by that instrument. The connections for
A« «>eetrometer test are shown in the accompanying figure (Fig. 4).
{
ELECTWMIETEa
(
ltd. 4.
B is a battery of about 10 cells.
^j is a batteiy of 100 or more cells.
324
CABLE TESTING.
As in the preoedins test, it is here Mghly essential that the insulation ef
the trough should be practically perfect, or at least known, so that if not
perfect, proper deductions may he made for deflections due to it alone.
To test the insulation of the trough, depress K„ and close switch S, Thk
ehaiges the quadrants of the electrometer, and produces a steady deflectlai
of its needle, and shows the potential due to the small battery B. Now
open switch S, still keeping a^ closed, and watch the deflection of needls
for about two minutes. IS the insulation of the trough is not perfect, thert
will be a circuit, so to speak, from the earth at the trough to the eaitk
shown in the flgure, and a fall in the deflection will be the result. If, hov-
erer, the drop of potential is not more than is indicated by a fall of two cr
three divisions, the insulation of the trough will suffloe. The electrometer
is discharged by closing switch 5. which short-circuits the quadrants, K,
being open at this time. The loint is now connected as in the figure.
Switch S is opened|and key K„ depressed, thus charsing the joint with the
large battery^,. This produces a quick throw of the needle, dne to the
charging of the Joint. Next, keeplng/f^ closed, discharge the electrometer
by closing switch S for a moment. The switch is then opened, and If the
Joint is imperfect as to its insulation, the deflection will rise as the e]ee>
tricity aocuniulates in the trough. The deflections are recorded after one
and two minutes, and are compared, as in the previous test, with a piece of
perfect cable. The results obtained with the Joint should not greatly a-
ceed those with the cable proper.
Capacity tests are usually made by the aid of standard condensera. Con-
densers, or sections of the plates of condensers, may be arranged in parallel
or in series (cascade).
AmMiC«aneM« of GoBdeaaera— Parallel.— Join like terminals
of the condensers together, as in the flgure : then the Joint capacity of the
oondensers Is equal to the sum of the respectlTC capacities.
Capacity, C=z € + €,-{- e„ + c,,„
X
X
x-~i
z
»wl
Fig. 6.
CoBd«Ba«n la Aertea or Caacado. — Join the terminala, as la
Fig. 6. The total capacity of the condensers as thus arranged is equal to
the reciprocal of the sum of the reciprocals of the several eapaoitlea, or
1
Capacity in series = lil..J_.JL
FlO. 6.
Condensers are now constructed so that these two methods of arranging
the plates of a condenser mav conveniently be combined in one condenser,
thereby obtaining a much wider range of capacities.
1
CABLES.
325
CapacHj kj IMrvct lMwlui>S«.— It iB ftMiumitly d^
ilnMe tolmow the eafMoity of » oond«iiaer, a wire, or a cable. This may
be awertaiaed by the aid of a standard oondenaer, a trigger key, and an
attatte or ballistio galTanometer. First, obtain a conttarU. This is done by
■otiBg Uie deflection d, due to the discharge of the standard condenser after
s eiisi|s of, say, 10 seconds from a giTcn E.M.F. Then discharge the other
eoadeoMr. wire, or cable through the galvanometer after 10 seconds charge,
•■d note IM deflection df. The caitacUy e' ot the latter is then
c hdag the ci^MwIty of the standard condenser.
GnyfBcHy ^y TIiobmom** Metk««.— This method is
'tsln
■eeonte results
used with
testing the capacity of long cablet. In the flgnre (Fig. 7)
l=- ukthI
I
FlO. 7.
'= battery, say 10 chloride silrer cells.
t= adjustable resistance.
B= lized resistance.
ttiritalTanometer.
C zz atandard condenser.
1,2, 3, 4, 5, keys.
To (Mt, eloae key 1, thus connecting the battery B. through the resist-
•Be«B£,A^ to earth. Then
F: r,::R:E,
vWa Fand F, = the potentials at the innctions of the battery with Jt Jt^.
Next close keys 2 and 3 simnltaneonsqr for, say 6 minutes, thereby char-
M the condenser to potential V. and the cable to potential V,
l«t Cbe the eapacitv in microfarads of the condenser, and C, capacity of
cable, and let Q and Oy be their respective charges when the keys were
*•?!??: '^^^ Q:Q,::VCi V,C,.
Open kejB 2 and 3, keeping key 1 closed for say 10 seconds, to allow the
cBargee of cable and condenser to mix or neutralise, in which case, if the
eif^ ve equal, there will be no deflection of the galvanometer when key
«« eloied. If there is a deflection, it is due to a preponderance of charge
n Cor Cf. Change the ratio of it to jR^ until no deflection occurs.
■nwn. VC= V, C,
Batwefoond V,\V\\R,\R
•^ C,-=z% C microfarads.
(
(
326
CABL£ TESTING.
CapAcMor 1»7 Cl«tt*« H«tk«d.-~Fic. 8 ahowB the oooaeeikMM far
teBtiuff the influlation of » cable by this method, whidi ie oonndered m»ii»>
whatbetter than Kelvin's, aa it does not necessarily require a well insulated
battery.
First adjust the resistances R and Ri to the proportions of Ci to C. ss
nearly as may be, by moving the slider 8. Depress K for five aeeonda,
which will charge both cable and condenser. At the end of the time, de-
press k and observe if there is any deflection of the galvanometer O. If
there be any such deflection, open k again, let up the key K, and shori-
55
miiiiiiiii
?
*\AJv%A^>A/WW^^^^>/\^N^>5|r^/N/v
L ^(2Pi c.ini
Ocound
\
Fio. 8. Qott's Method of Cable Testing with Condenser.
eirouxt the condenser Ci with its plug for a short time, then readjust R and
Rt and repeat the operation until there is no deflection of the galvano-
meter O; uien
C I \j\ I I iC% I K
and C - ^ C,.
llie best conditions for this test are when R and R^ are as high as poiH
sible, say 10,000 ohms, and C| and C are as nearly equal aspossible.
X«stiBr Capacities by I.ord M.elvte*s I»ead-S«ttt, M«Ui-
oelliil»r Toltmeter. — Suitable for short lengths of cable (See Fig. 9.)
MV ■■ multicellular voltmeter.
ilC -• air condenser.
B-" battery.
iS— switch.
Qoi total charge in condenser and Af V, due to battery.
Ca — oapaci ty oi AC.
(76— capacity of cable.
First dose switch S on upper point 1 and charge MV and AC to a desired
potential, V. Next move switch S from point 1 to lower point 2, and note
the potential V, and MV.
Then Q' - V (C+ Co)= KCC + Ca + Cb). where r in the capacity of volt-
meter. Ordinarily C can be neglected, as comparea with the capaoitiea of
AC and the cable, in which case, by transposition,
C6-(y-7/)Ca- V,.
1
CABLES.
327
OondueUNrB of telephone cables are measured for eapaoity with the lead
•heathinc of annor and aU oondoetois but the one under test grounded.
Fio. 0.
_ Brealca la Calll«e or OT«rlam4l Wiroa by Capa-
city TmtaT— When the capacity per mile or knot of the oonouotor of a
cible ia known ita total capacity up to the break ia measured by comparison
Ma
with a standard oondenaer. Then z^ —,, x being distance to fault in miles,
m
sr espseity of eondncCor per mUe and m total oanacity of conductor from
the testing station to break. ▲ dear break in the cable or conductor is
la GalblM or Aairlal ^iTtvaa^-Ptof. Ayr-
■To locate the oross at d (Fig. 10) arrange the connections
'tfTnnr
Fio. 10,
•tihown. This Is ylrtnally a Wheatstone bridge, in which one of the wires,
a, Is one of the arms of same. Adjust r until a (« + y) = ftr, when r will be
HWl to a 4- y , if a = ft.
d
{
I
Fig. 11.
328 CABLE TESTING.
Next eonnect the hattery ^ line m fnatead of to earth, as In Ills. 11,
adjust a until ax = by.
X h
and as X 4- y = r in the first arrangement,
henee, « = j-j-^.
This test may he yarled hy transposing O and the battery, in Fig. 9, whUk
is the old method of making this test.
liocatlnr S^nlte !■ Aerial inr«a •w Cablea bj «li«
Test. — Two conductors are necessary for this test, or both ends of a
must be available at the testing-point. Also it is assun^ there is bat
defect in the conductor. The resistanoe of the fault itoelf is negligible la
this test.
Measure the resistance L of the loop by the ordinary Wheatstone bridss.
Morraj Metbod.— Connect as in Fig. 12, in which a and 6 are the
arms of a wheatstone bridge, and y x are resistances to fault, the eondao-
tors beins joinedat J'Cin the case of aerial wire, for instance). Gloeekey
and note the deflection of needle due to E.M.F. of chemical action at faalK
if any. This is called the false sero.
Fio. 12.
Now applT the positive or negatire pole of the batteir, by depressing one
of the knobs of rerersing key A*, and balance to the false seropreTioosly
obtained by varying the resistance in arms a or 6. Then, by wheatstone
bridge formula,-
axzz hy,
and l = x -\-y
y=zl^x
« = r—.l
a-\- b
y = p-r L
To ascertain distance in knots or miles from 2 to ^, divide x by resistanos
per knot or mile ; to ascertain distance from 1 to /^, divide y by resistance
per knot or mile.
The foregoing test is varied in the case of comparatively short lengths of
cable, in the manner shown In Fig. Idy in which the positions of the battery
and galvanometer are transposed. Otherwise the test and formula are the
same. It is advisable to reverse the connections of cable or conductors at 2
and 1 , and take the average of results obtained in the different poeitloot.
In this latter method, battery B should be of low resistance, and well insu-
lated.
Best conditions for making test, according to Kempe. — Resistance of (
should be as high as necessary to give required range of adjustment in a
"^
CABLES.
329
9 of SBlvAnometer should not be more than about five times the
of the loop.
Fia. 13.
Tari«7 Mj^mp T«flt. — Measure resistance of loooed cable or oonduo-
ton as before. Then connect, as shown in Fig. 14, in which r is an adjustable
ifBstanee. If currents due to Ifault be present, obtain false sero as before.
Thai dose key K, and adjust r for balance. In testing, when earth current
IB pRMnt, the best results are obtained when the fault is cleared by the
MtpLtire pole, and just before it begins to polarise.
Fio. 14.
Then
X —
L -r
«We X fa the distanee of fault, in ohms, from point 2 of cable proper.
Tbeo X •+■ by the resistance of the cable or oonduotor per knot or mile
Vnt ths distanee of fault in laiots or miles.
When the resistance of the **good" wire used to form a loop with the
«f«etive wire, together with that portion of the defective wire from J to F,
a leM than the resistance of the aefeotive wire from the testing station to
wilt, the resistanoe r must be inserted between point 1 and the good con-
<iiutor, the defeotive wire being connected directly to point 1. The formula
i> thii ease is x "- — x — . x, as before, bang the distance to fault in ohms.
Vb localise Wmmit wliea lieeleiaBc* of CoMdvctor ie
u«WBMiA a Paralleil CFo«d Wlr« ieMot A Tafllable.^ Measure
'>J Wbeatstone bridge resistance (r) from A to earth through fault F^ and
f^iiBtuice (r^ from A' to earth through fault, Fig. 16. Let li be resistance
of coodnetor from Aio A'^* the actual resistance of conductor from A to
' and y actual resistanoe of oonduotor from A' to F,
i
(
« —
R +r - f
330 CABLE TESTING.
and V-
in ohma, from wfaioh th« datanoe in feet or miles may be oaloulated.
A R A
r
Fn. 16.
r
liOCAtlar Faalte im lMMa»t«d fTliwe.— The following. w» (o
speak, ** rule of thumb," or point to point electro-meehanical meiliodi of
locating faults in unarmored cables, in which the defect is not a prononnoed
one, haye been found snccessf ul.
fFarr^B'a BIetli«4«— The cable should be coiled on two insulated
drums, one-half on each drum. The surface of the cable between the dnuns
is carefully dried. One end of the conductor is connected to a battery which
is grounded. The other terminal is connected to the Insolated quadrants
of an electrometer, the other pairs of quadrants of which are connected to
the earth. Both drums being well insulated, no loss of potential is obeerred
after three or four minutes. An earth wire is now connected first to one
and then another of the drums, and the fault will be found on the drmn
which shows the greater fall on the electrometer. The coll Is now uncoiled
from the defectiye drum to the other drum, and tests are made at Interrali
until the defect is found.
F. J'ttcob coils the core from a tank to a drum. The battery is
nected between the tank and the conductor, one end of whidi is free. A
galvanometer is joined between the tank and drum, which need only be
partially insulated. The needle shows when the fault has passed to the
drum, and it can be localised by running the galvanometer lead lUons the
insulated wire.
Copp«r Keeletence, or CwBdnctlTlty of C»blea«
The copper resistance of the submarine and underground cables used in
telephony and tdegraphy is always tested at the factory, usuallv by the
Wheatstone bridge method. In such a case both ends of the cable are ac-
cessible. Whcb the cable is laid, if the far end is well grounded, the oop-
per resistance may be measured, either by the Wheatstone bridge meCliod,
or by a substitution method, as follows: First, note the deflection due to
copper resistance of conductor. Then substitute an adjustable resistance
box and vary the resistance in the box until the deflection equals that due
to cable. This latter resistance is the resistance of the cable. If there are
earth currents on the cable, take readings of cable resistance with each
pole of battery. Should there be any difference between the results
obtained with the respective poles of the battery, the actual resiatanee
will, according to F. Jacob, be equal to the hannonic mean of the two
results, i.e.,
where R is the actual resistanoe, r is the resistance with •(• pole, i' is the
resistance with — pole.
To measure copper resistance of conductors by the voltmeter, first
measure the E.M.F., V of testing battery. Then place the voltmeter in
series with the battery and conductor or instrument to be tested| exactly
as a galvanometer would be placed, and note the deflection V in volts.
It win be less than in the first instance. Unknown resistanoe z will be
found by the formula:
where r is the resistanee of the voltmeter ooiL
CABLES. 331
Tk«» C«re of the cable, that Is, Uie insulated oopper conductor, Is
made, as a rule, in lengths ox 2 knots, which are coiled upon wooden drums,
ind are then immersed in water at a temperature of 76^ F. for about 34
boTm. The coils are then tested for copper resistance, insulation reeia-
tanee. and capacity ; the results of which tests, together with data as to
length of coils, weight, etc., are entered on suitably prepared blanks.
iJter the tests of some of the coils have been made, the Jointing upof
the cable begins, which Is followed by the sheathing or armoring. The
jotntB are tested after *24 hours immersion in water. I>uring the sheathing
. proeeM, continuous galvanometer or electrometer tests are made of the
core, to see that no Injury befalls the cable during this process. In fact,
pnctkally eontlnuous tests of the cable for insulation resistance, copper
rcaiitaiice. and capacity should be made until the laying of the cable b^ins.
During laying, the cable should be tested continuously, and communica-
tion ihonld be practically constant between the ship and the shore. An
anangsment to permit such tests and oonununioation is shown in Fig. 14.
OABLt
V//////////y///y
Fro. 10.
hi tUs ^ure, Oi is a marine galvanometer, B is a battery of alx>ut 100
Mb on dup-board. In the shore station, L is a lever of key JiC, C is a con-
t^eoiw, 0} IS a galvanometer. Normally key K is open and the cable is
charged hy battery B, If. while the cable is beinjg paid out a defect occurs
ia the insulation, or if the conductor brealcs, a noticeable throw of the galva-
ooneter follows, and the ship should be stopiied and the cause ascertained.
By pr^arrangement the lever of shore key K is closed, say every 6 minutes,
thereby charging the condenser C, which causes a tnrow of the galvano-
neten' needles. If the ship or shore fails to get these periodic sipials, or
if they vary as to their strength, it indicates the occurrence of a defect.
At the end of every hour the snip reverses the batterv, which reverses the
weetkm of the deflection of the galvanometers. Ii the ship desires to
mnnumieate with the diore, the battery is not reversed at the hour, or
» ravened before the hour. If the shore wishee to speak with the ship, the
W JT is opened and closed several times in succession. In either event
with eonneet in their regular telegraphing apparatus for conversation.
Gmap^uiid CablttSt that is, cables of more than one conductor, have
their eonductora connected in series for these tests. If there is an even
umber of conductors, two of them must be connected in parallel.
ittefT Faolta la VsAerrroaad Cables.
-. .^..v.-.^ • ..^ult in a c
dowtive conductor and
Iiocatiair Faalta la VaAerrroaad Cables. A
TV> loeaHse a fault in a conductor ol a cable, form a loop consisting of the V
u*f«tive conductor and a x'^A i
VMd conductor of equal resis- ^ { \\
tanoe and length, with battery / V"/
* a •hown.Tig. 17. Place y
>n ammeter in each leg of
«»p \' If current in leg A — ^ ^ / a \" r
to fault F ia /, and current .r— . E ^'•*— { T ) i
»nleg/'tofaultis/':Pbeing T vLy I
^b of loop L and X the i 4
«««M»fiain A' to fault J?, ^ ^
Fro. 17.
332
CABLE TESTING.
then
/'
D-x
andz —
IL
The compttM method of locating faulte in underground cables oonaista*
briefly, in sending a constant continuous current of about 10 amperes infco
the cable through the ground, the current first passing into an automatie
reverser which reverses the direction of the current flow every ten seoonda,
A manhole is then opened near the center of the cable length and a pockeC
comnass laid on the lead sheathing of the faulty cable and observed for
say naif a minute. If the ground is further from the source of reversed
current the compass needle will swing around approximately 180^ upoA
every reversal at the end of each ten seconds interval. The manhole m
immiediately closed and another opened, say a mile further away from the
source of test current, and if no motion of the compass needle occurs, then
the fault has been passed and another manhole is opened between the two
first positions, and so on until the fault is finally located in a section be-
tween two manholes. H, O. SUM, in Trans. A. /. E. E,
Hirli V»ltace or IMelectric Teato of CaMm or OOMr
Gables intended for high pressure circuits ranging from 500 to 60,000
volts or more are usually tested at the factory to ascertain their ability to
withstand specified voltages. For
the lower voltages the cables are
^netallv tested for three or four
times the contemplated working
pressure. For higher voltages the
cables are usually tested for one and
a half to twice the working electro-
motive force. iSss ttandcardiaoHon
ndeBofA.I.E.B. The present limit
for undernound power cables is
about 30,000 volts. The alternat-
ing electromotive force for these
tests is supplied by specially de-
signed step-up transformers, which
must be of suflSdent kw. capacity
to supply the charging eurrent called
for b^ the eable to be tested. The
charging eurrent varies directly as
the frequoicy, directly as the
E.M.F.. and aireotly as the statio
capacity, and as apparent enercr
(Skintter. EUdrical Age, Julv, 1905)
is equal to current multiplied by
E.M.F., the apparent output of the
transformers reauired must vary
directly as the frequency, directly
as the square of the E.M.F., and
directly as the static capacity in
microfarads of the cable or apparatus under test. ^ For example an under-
ground cable having a statio capacity of one microfarad, and tested at
20,000 volts, 60 cycles, requires a testing transformer of 160 kilowatt capao-
ity; tested at 40,000 volts the same cable would require a testing trans-
former of 600 kilowatt capacity. The testing electromotive force is regulated
hi several ways, for Instance, by means oi a rheostat in the field of the
generator, as in Fig. 18, or by employing a number of small transformers
capable of being connected up, as indicated in Fig. 19, in which the range is
from 10,000 to 40,000 volts in steps of 10,000 volts. The voltmeter or toI-
Fio. 18.
i
^i
"o'^.F
- - -, ioof prinaiT
er, or the voltmeter may be Disced directly in the
I m the IntiDjf circuit is Imiueptl^ employed
've £000 volti. to ■ »ble or
IK its iiuulHtion. care ihould
Ignited; And for thia it 'im
the Intini; truuformer iwd
try. gsUEiiiE their poinli at
miltee of elaDdudi d the
ig the voltmeter « Ibe pm-
1. what the indicktiou el the
r rheoet'ta eoniletliis
1 ailed with w
r,Duke
••■b r«r CbKIo E>«i<. — All lead-covered cable end* rboald be pro-
tected from dAmage bv fltatlo dUcbarga bv Aarad ends or bella, that li. by
anlarnneiit of the lead ibeath to Fully tv(ce the dlsmeter uf tb* lead over
the cable, for a dlstaooe of about a fnot. Lead or bran cable headi or
belli are niDcb Died on the endi of hiib patenilal underinnuid oablea.
Tbli bell etaonid then be fllled with aome gnod Iniulatlna material like
Chatterton Compnaod, the eondactor ende, In CAM ol maluple oODdnetor
(Sblea, batug carefully aeparatad and Brrangad.
s;
DIRBOT-CURRBNT DYNAMOS AND MOTORS.
Rbyibbd by Cbcil p. Pools and E. B. Raymond.
Bzoept where other deflnltions are ffiyen, the definitions of the Bymlwilfl
used throughout this section are as f oflows : —
A = Area in square inches.
^ = Aggr^ate area of all brush faces.
; = Magnetic density in armature core body at full load.
«»= Magnetic density in field magnet core at full load.
= Average magnetic density over pole-face at full load.
T = Magnetic density in armature tooth tops at full load.
1^= Approximate magnetic density in armature tooth tops at full load.
:= Magnetic density in armature tooth roots at full load.
/ = Approximate magnetic density in armature tooth roots at full load.
;r = Magnetic density in armature teeth at a specified point,
r'rr Approximate density in armature teeth at a specified point.
= Brush-face dimension crosswise of commutator bars,
y = Average distance between interpolar edges of adjacent pole-faoes.
Z>c "=. Diameter of armature core over teeth.
Dk = Diameter of commutator barrel.
/)• = Diameter of central hole in armature core.
Dp = Diameter of pole-face bore.
Dt = Diameter of circle drawn through narrowest parts of armatare oore
teeth.
d = Diameter of bare round wire, in miZ«.
A = Depth or thickness of winding in a magnet coil.
3 z= Air-sap length from pole-face to tops of armature teeth.
S = Total E Jtf .F. generated in an armature.
Bw = E.M.F. delivered by a dynamo or applied to a motor.
e = E.MJ?*. at terminals of one magnet coil.
JF = Ampere-turns per pole required by complete magnetic eircalt at
full load.
Fq = Ampere-turns per pole required by complete magnetic olreuit at
no load.
Fa = Ampere-turns per pole required by armature core at full load.
Fg = Ampere-tums per pole required by air-gap at full load.
Fm ■=. Ampere-turns per pole required by magnet core at full load.
Fp = Ampere-turns per pole required by pole-piece or shoe at fall load.
Fr = Ampere-tums per pole required to balance full-load armature
reaction.
F» = Ampere-tums per pole in series field-winding at full load.
J^«A = Ampere-turns per pole in shunt field-winding at full load.
Ft = Ampere-turns per pole required by armature teeth at full load.
iV = Ampere-tums per pole required by field-magnet yoke at full load.
/ = Ampere-turns per inch length of magnetic path at full load :
Subscripts a, m, p, t and y apply to armature core, magnet core,
pole-snoe, armature teeth and magnet voke, respectively.
(7 = Girth or perimeter of a complete magnet coil.
g = Girth or perimeter of form or bobbin on which a magnet coil it
wound.
h = Depth of armature coil slot.
la = Total armature current.
Ith = Shunt field current.
/w = Current delivered from a dynamo.
i = Current in a specified conductor, or coil.
«• =r Current in each armature conductor.
Am = sin (180 ^-^p); hat Dp = chord of polar arc.
kff = a coefficient ; ib^ £ = increase of air-gap span due to fiux spread.
i^ = a coefficient ; 1^6=. increase of air-gap width due to flux spread.
ic» = Number of commutator bars between the two to which the terml>
niUs of each armature coil are connected.
834
NOTATION. 835
Im = Length of magnetie path In umatnre oore beneath slots.
1/ = Length of a epeeUlea lield-magnet coll parallel to flux path.
Lm = Length of magnetlo path in one field-magnet oore.
Im = Length of magnetlo path in one magnet pole-piece or shoe.
If = Length of magnetic path in fleld-magnet yoke between adjacent
It = iStel iisngth of each annatnre oondnotor.
SI = Number of windings in a multiplex armature winding.
Jf« = Total number of armature conductors around armature periphery.
Kk = Number of commutator bars and armature coils.
^« = Number of armature teeth (and slots).
m = Maximum number of commutator bars simultaneously in contact
with one brush at any instant.
F =Goefflcient of magnetic leakage.
P^ = Total watts loet m armature.
f = Total watts lost in armature excluslTe of projecting parte of tha
winding.
A = Watts lost at all brush faces.
P, = Watts lost by eddy currents,
ft = Watts lost by hysteresis.
Pr = Watts lost in entire armature winding atone.
P/ = Watts lost in armature winding excluslre of projecting parts.
/». z= Watts lost in series fleld-magnet winding.
P* = Watts lost In shunt fleld-magnet winding.
Pw = Watts of dynamo armature output or motor armature intake.
p = Number of fleld-magnet polos. ^ _^ ^.
0 = Number of parallel paths through an armature winding :
NoTK :--In a multiplex lading, q = total paths in all the
windings. ^ . .
Jl = Resistance of armature, commutator and brusnes, warm.
& = Resistance of armature winding, warm.
JU = Keeistance of embedded part of wrmature winding, warm.
A =MectiTe resistance of aU brush-face contacts; 7.R» = Volts drop
at brush faces. , ., . w
r =: Resistance of a speclfled conductor or coil in ohms.
r.p.in.=: Rerolutions per minute.
r.pA = Revolutions per second.
1 = Width of one armature coil slot.
T' = Torque in pound-feet.
T rr Width of one armature tooth at the top. * ^ ^ »«
I = Wld^ of one armature tooth at the narrowest part, exeept in
equation 82 and Table V. „.*i^« tM ^^a
I = NmSber of turns per armature coil ; only in equation 32 and .
Table V. M
9j^ =z Temperature rise of armature, Fahrenheit degrees. ■
•k = Temperature rise of commutator, ^^o«^\«l* degrees. 1
•t = Temperature rise of fleld winding, Fahrenheit degrees. ^
T = Width of one armature tooth at a speclfled point.
♦ = MaSetlc flux passing from one pole^f ace to armature at full load.
♦• = Magnetic flux in magnet core at full load.
♦» = Magnetic flux In one air-gap at no load.
tm^ — MAffnetIc flux in magnet core at no load. .
r = ISS spSn 5- polo-pftch = proportion of armature circumference i
coTcred by all pole-faces. I
» = Volnme of iron or steel, cubic inches. ^
«• = Volume of iron or steel in armature core body,
w = Volume of iron or steel in armature teeth,
r. = Gross length of armature core, between end plates. _ « q ^
«. = Net measurement of armature core Iron parallel to shaft = 0.9 X
/ Wm — ventilating ducts).
Wh = Width of commutator barrel, parallel to shaft.
IFp = Width of pole-face parallel to shaft.
HOTK.— All dimensions are in inches, except wire diameters.
336
DYNAMOS AND MOTORS.
FU]!ri»AMEirTAIJI.
One Tolt is generated in anelectrical oondootor by tbe *^eiittl]R£'* oC
100,000,000 maxwells per second.
One volt 1b generated In a looped or coiled conductor by a uniform Taria-
tlon of magnetic flux threaded through the loop or coll when the
rate of change is 100,000,000 maxwells per second.
Consequently, Uie E.M.F. generated in any direct-current armatnro is
E=z*N0^r.p.8,l(r*
(1)
Dynamos are
Serles-wound, to dellTer constant current,
Bhimt-wound, to deliTer approximately constant E.M.F.,
Compound-wound, to deliver strictly constant E.M.F. at some point in
the work circuit.
The entire field winding of a series-wound machine is in series ^rith its
armature, and therefore carries the full current ; an auxiliary regulator is
required to maintain the current constant under varyins loads.
The field winding of a shunt- wpund dynamo is connectidd to Its bruahes in
series with an adjustable resistance (rneostat) : as the load increases, the
drop in the armature wlndinff and connections increases and the ayailable
E.M.F. at the terminals is thereby reduced, necessitating adinstment of
the rheostat to strengthen the field excitation and bring the terminal
E.M.F. up to normal.
A compound-wound dynamo ia proyided with a shunt field winding oan-
nected either to its brushes or to its main terminals, in series with a rheostat,
and an auxiliary winding of relatively large conductor connected in series
with Uie armature. The shunt winding excites the machine to normal vol-
tage at no load ; the application of a load causes the field excitation to be
strengthened by reason of the current flowing in the series winding. The
series winding is proportioned to increase the field strength in reeponee to
any increasein load, to such an extent as to maintain the proper E.M.F. at
a predetermined point in the work circuit. The rheostat in the shunt field
circuit is for the purpose of adjusting the no-load E.M.F. within praotical
limits.
The relation between fl^d excitation and generated E J!iI.F. is shown by
the " magnetization characteristic " curve. See Fig. 1. The early part
of the curve is practically a straiight
line because the iron or steel in tne
magnetic circuit has such high perme-
ability at low degrees of magnetixatton
that the flux Is almoet directly pro-
portional to the exciting toree. As
the iron or steel approaches sat-
uration, the permeability decreases
rapidly and a given increase in excita-
tion win not produce an increase hi
flux equal to the Increase produced
by the last previous equal increase
ill excitation ; hence the sharp bend
in the curve. In constant-potential
machines, the magnetic eircmt should
be proportioned so that at no load
the characteristic curve has corn-
intersection of the lines a and e in the
-TMMt OH PIKLO
Oil ounmirr w nckM
Fig. 1. Magnetisation Curve.
menced to bend sharply, as at the
diagram ; the lines b and d indicate respectively the total internal E.M.F.
f generated at full load and the ampere-turns required to produce it, and their
ntersection establishes the point on the magnetization curve oorreqionding
tofuUload.
DYKAMO CHARACTERISTICS.
337
Ckaracterintlc— This corro li acurreof regnlto, in
which the dyiiAmo is excited from its own current, and with the speed con-
etaat, the terminal Toltaee is read for different values of load.
The ennres for series, shunt, and compound wound machines all differ.
The obserratlons are best plotted in a curve in which the ordinates repr»*
■ant volt values, and abscissas amperes of load.
Seriu dynamo. In a series machine all the current flowing magnetises
tbe field, the volts inorease with the current, and if fully developed the
carve is somewhat like the magnetisation curve, being always below it.
however, due to the Ices of pressure in overcoming internal resistance ana
armature reactions. The diagram. Fig. 2 (armature reaction being neg-
lected), is a sample of
the external characteristic of a series dynamo.
To oonstmct this curve from an existing
machine, the curve of terminal voltage can
be taken from the machine itself by ariving
its armature at a constant speed, and varying
Ike toad in amperes.
The curve ** drop due to internal resistance,"
sometimes called the " loss line,*' can be con-
stmeted by learning the internal resistance
of tiie machine, and computing one or more
values by ohm's law, and drawing the straight
hue through these points, as shown.
The curve of total voltage is then con-
structed by adding together the ordinates of
the ** terminal volti^e " and " drop due to
iatemal resistance."
A very good sample of curve from a modem
series machine is to be found in the following
description of the Brush arc dynamo.
llg. 3 is * characteristic curve of the new Brush 125-lt. Arc pynamo
MWUIUUMO
Fig. S. External Charac-
teristic of Series Dynamo.
as
1 —
__
—
^~
^^
^
•MO
/
/"
\
CflflB
z
>
SMO
MQQ
4M0
«M0
f
tMO
J
/
mmm
/
m»
/
uoo
oHARAOTemsno curve
vmy^at rkv. pm mm.
vm
MO
,f
:
1
1
1 i
1
\ <
AM
r (
PCW
i 1
> u
> 1]
I 1
1 1
1 1
1
(
Fio. 3. Characteristic curve of Brush 125-LIght Arc
Dynamo wltixout Regulator.
AND MOT0B§.
maohine wlthant ui; r«aol>tor. Tlie rtadlnsi v*r« ti\ Ukan at tim iDart-
leupocltlonofcoRimutation. ThJi enrre l> remarkable from tbe fact tbat
afUir we get over tbe benil, the curre Is almuet perpeDKcular, and t* prob-
ably the neareflt approach to a conAtoDt ourreot machlue ever attained.
By irlndliie more wire on the armaCure the maehlue eonld ha*e bean made
to deliver a ooiiBtaDt ourreat of ft.O amperea at all loada, wltbout •hoiiUiiff
bu
thii
dbave
dthelDtemal
machine
much
lent at light
slat
e-qiiartsT load
atfi
the
gal
being
aim
»t
one eleetrioal
my of the cnirent f ton
Pie. 4 la a curve at the electrical elDcleDflT. It vlU be notioad that thll
at full loul reachei H per cent, whloh is accounted for by the liberal allow-
clrcnlt, and by the large il» of Che vire lued on both Held and airaatBra.
Fig. fl la a curve of the commercial efficiency. At full load thia la >Tar
90 per cent, and approaches very cloaely tbe etDclency of Ineandeaeent
dyiiamoB of equal capacity, but the moat noteworthy point la the high aft-
cfency phuvrn at one-qaarter load.
Fix, S la scorve of the machine separately eidted, with DO etureat in tbs
armature. The ordlnataa are the volla at the armature larmlnala. and tha
alwclstir the ampereg In the field. Thli la Id reality a pemeablllly OBTre ot
the magnatlo circuit. By a comparison ol the tollage ihimMn iriun
DTlfAMO GHARAGTEBISTICS.
339
1
tbere ve Bine amperes in the Held, with that of the machine when dellTer-
faig eamnt, can be seen the enormous armature reaction. The onrTe also
■
^
"^
mo
X
r^
^
^
MOO
>
/^
r
/
moo
/
j
NOO
T
1
"t
f
■
4000
•000
tooo
E.M.P.
•
BlOO
BOO
1
1 1
1 1
i
k (
i (
1
r
1 {
1
A 1
1 1
1 1
t 1
4 1
%
Fig. 6. Permeability Gurre <rf Magnetic Oironit
of Brush 125-Li£ht Arc Dynamo.
indicates a new departure in arc dynamo design, namely, that the mMnetio
ciremt is not worked at nearly as high a point of saturation as in the old
tjpes.
Skmt dynamo. Tlie shunt dynamo has, besides an external characteritHc,
■bovn below, an internal characterisHo. The first is developed from the
Tolii read while the load in amperes is being added, the armature reyolu-
Uons being kept constant (See Ing. 7.)
Adding load to a shunt dynamo means simply reducing the resistance of
tbe external circuit. With all shunt machines there is a. point of external
mistsnce, as at n, beyond which, if the resistance is further reduced, the
Tolts will drop away abruptly, and finally reach zero at a short circuit.
,.-'
}n
i
Miftwe T^Km m f leto
0 b
Fig. 8. Internal Charaoter>
istio of Shunt Dynamo.
^10. 7. External Characteristic
of Shunt-wound Dynamo.
The internal ehairaeterisHe^ Fig. 8, or, more correctly, curve of magnetiza-
tion, of a shunt dynamo, is plotted on the same scale as those previously
deoeribed, from the volts at the field terminals and the amperes flowing in
ttie fleUtwinding.
DYNAUOS AND MOTORS.
Til* nditanea Ui
a to tlia potnt a on tba onrre. ukd tb
leo aonlj kppllea t- . — r— - _ —
__„ b lot (bat polac ia detsnnliiail bjohnu law, or ■■ fat
lows : Am the aurre oE magDetiiatloD Ig dctermliiea from tbo rakdln^ of
nlto plotted Tcrtlckllj ksd ampeiei hoiliantall j, and m r = y or r = ^-i
1 -—i^Uiagaob, therafors the resljtuMs M kny point on UucnrroTlD
u'of the
obtaload
i«of aoB-
■tdenble importuioe vhore mora tluB
one drnuno la to be B>nneet«d to tlw
Mune olronit, or when close reKnlalliia
Fig. II la a Eunple oorre from m oamt-
ponnd-woond dynamo, where the ia-
oreue of munetlzatfon of the tlddi
dae to the leris oolla and load oaniM
tbeCecmlnalToltaeetoilMaathelaHl
)■ Inorsaaed. Tbla la commonly dOM
" ke DP for drop In feeden to Of
,r,Buaa 1 of dlsCrlbaUon. It la Imptal-
' ble In ord[nar7 oommerolal drnanua
to make thla enrre oloael; approach ■ atralght line, aod the antfior baa
tODDd It dllBcalt tor good makea to approaoh a alralght line of regoiatlia
nearer than It per cent elthar aide of it for the extrame rarlatlon.
Ctarre vr MacHiIM IMalrlkatl**. — This ourre la oonatmctad
from ailatlng djnamoa to show the dlatrlbntlou of (he Held aboni the pola-
K'neee; II can be platted on (heregolai rectangular eo-ordinate plan, or oa
epolar co-ordinate.
The foUowingcDt* lUnatrate the commoneat mathoda of settins the data
for the onrre. Wltb the djmamo ranalng at the ipeed and load dealr«d, (he
pilot broah, a, in Tig. 10, or the
la started at the brnah x. and 'morlng
the difference In Tolte between the '
bruah, a, la read on the Toltmeter.
ARMATURES. 341
Dtreet-enrreiit armatnres are diylded lato two ffeneral f onus. — drwit arm«-
toxea. In whieh the condnctors are placed whoUy on the snrtaoe or ends of
a ejlindrlcal core of iron ; and ring armatures, In which the condnetors are
wofuid on an iron core of ring form, the eonductors helng wound on the out*
side of the ring and threaded through its Interior.
Another form need somewhat abroad is the disk armature, in which the
eoBdnetors are arranged in disk form, the plane of which Is perpendicular to
the shaft, and without iron core, as the disk rerolves In a narrow slot be-
tween the pole-pieoes.
Annatnres of the slotted or toothed core type are almost exolusirely em-
ployed now. The coils are set into the slots, with the results that eddy cur-
rents In the conductors are prevented and the conductors are positlrely
driTsn hy the core teeth. The cores are built up of sheet steel disks in small
siMs, annnlar sheets in medium sises, and staggered circular segments la
largi slaea ; the steel Is from 16 to 2S mils thick and the sheets are clamped
firmly together by end-plates. In order to prevent eddy currents in the
core, the dlaka or sheets are either coated with an insulating varnish or
separated by tissue paper pasted over the entire surface of one side of each
disk or sheet.
The toothed armature has the following advantages and disadvantages as
compared with the smooth body:
1. The reluctance of air-gap Is minimum.
2. The conductors are protected from injury.
S. The conductors cannot slip along the core hy action of ^e electrody-
aaBiie force.
i. Eddy eurreats in the conductors are almost entirely obviated.
6b If the teeth are practically saturated by the field magnetism, they
oppose the shifting of the lines by armature reaction.
I. More expensive.
S. The teetn tend to generate eddy currents in the pole-pieoes.
3. Seif-induetion of toe armature is increased.
If the slots can be made less in width than twice the air-gap, so that the
Ifaies spread and become nearly uniform over the pole-faces, but little
sffeet will be felt from eddy currents Induced In the pole-faces. When It is
not poasible to make such narrow slots, pole-pieces must be laminated in
the same plane as the disks of the armature core, or the gap must be eon-
ridcrably uicreased.
n^BteruiM In the armature core can he avoided to a great extent by using
the Dest soft sheet iron or mild steel, which must be annealed to the softest
point by heating to a red heat and cooling very slowly. Disks are always
poneheo, and are somewhat hardened In the process; annealing will
entirrty remove the hardness, and any burrs that may have been raised.
Disks should be punched to sixe so carefully as to need no filing or truelng
19 after being assembled. Turning down the surface of a smooth-body
snnatnre core burrs the disks together, and is apt to cause dangerous
1*****^ in the core when finished. Light filing is all that i8 permissible for
truing vp aueh a surface. Slotted cores should be filed as little as possible,
and can aometlmea be driven true with a suitable mandrel.
Armiatmre ahaftt must be very strong and stitT, to avoid trouble from the
nngBetie pull anonld the core be out of center. They are made of machin-
ery steel,_aDd have shoulders to prevent too much endwise play.
* X o
Cmrm Timsil«tln« — A great variety of material is used for insulating
tke eore, inelndlng asbestos, which Is usually put next to the core to prevent
damage from heanng of that part, oiled or varnished paper, linen, and silk ;
praasDoard ; mica and micanite. For the slots of slotted cores the insula-
tion ia frequently made Into tubes that will slide Into the slots, and the con-
ductors are then threaded through. Special care must be taken at corners
and at turns, for the Insulation is often cut at such points.
DYNAMOS AMD MOTOHS.
For kU Hull dTnainiia, ud In muijr of conildanbis gin, tbe wiadlDf ta
of doubla eatton-covared wire. Where tbe required oarryiug upuliy |« '
more Ibui thai of a Ho. 8 wire, B. & 8. gauge, the conductor inould b*
itruided for amootli-core arniatures. In liirge djoiuDaa, reotaugnlar cofB {
per bAn, oablea of twiAted copper, uid lanomeouefl luve cehU comprcMAd :
Into leoMngulM shape, are more camntoDlr lued. If the capper ban »« '
too wide, or wide enouEh eo that one edge uf the bar enten the fleld pereap
tlbly before tbe ramaiDUig parts of tbe 5sr, eddy currenti are Indneed la li ; :
■uch ban a» therefore made quite narrow, and It I* common to alope the -
pole-faoa a trifle, ao that tbe ban may enter tbe field gradually.
iItlhod$ or armngatttiu of v!indimii ate ol a moit oomplai nature, and
only theiDOet feueral [n u» will be daacrlbed bare, and theM only tn tbeorr ;
Panhall £ Uohart bar* dtHcrlbed aboat all tbe poaelble oombinatluoa ;
8. P. Tlioiii|iaoa,Uawkiua£Wallli,BudoCbare bare alio written quite fallT
on the iDbleot.
There are two fundamental types of armature winding : ring and dr
In a ring-wound armature, the core !■ nereuarlly anaular, tbe wire b>
wound tbrough the core as wall as along tbe eitarior, as Indicated In f
13 to is. This form of winding la now used only In aro-llghl dynamos
The llmpleet form of ring wlndluB [s the tvo-<:ir«ii( ilapir windiiu, wl
a conllnuoua conductor Is wound about the ring, and taps taken off to
*""■"""*•*- %t regular Interrals.
n this will be the mHJM-cirruil tingle wind ia^, d
-«.:
circuit winding can be crou-
occuPTlog ilmllar poelllons !
the lame commutator bar. I
number of commutator legmen
lo awib Mgmant luil«ad o:
Die aiuiit>ar of pol«,
Bat twOHti oibnubM uauvxtimij for Iha twoflrcnJC vlnilliin. anl
Ha corrflnt 1« hesTj «ioiu[h to rsqaire ■ long comicatator. In tEIoI) ci
dUmt Mta Df btnthea eta be added, up to tha noinlMC of pole*.
. mug WtivUns Croae-oonnected Co Bedaoe Uucqnol Indastlon,
lecllon type of this olut. oonduatora under sdjaeeDt Held
i
>ol« KTeeoDitMitod togetiieVio' that tbecirculu froia broah (o briuh are M
InJIanioed bj allthe^le* itnd^are tbereforaequal. __ .^ , H
lonioed b j all the pole* and .
[b the faN-rowuwnDii tfpe th
rted, mt that the coDdnclon
ii<n!t«, ■<• liuai me coDdnclon from bruah to briuh are Inauenoei
oaeiail the number of polee.
Tlie number of Mill Ina rvD-eimiif long-eotaiection tmtU^olar lei
■- d b; tbe lonnala
i
bar of paiTM of polea.
nie pitalk, y, u the namb
for Inatancet ui an armatni
,ber of colli adra
i. the b^nnlEK otcoirF+
i„gtoi
.. _ ._ iflngta
tana* between broabea for tbli olasi
^ItlpolMrtfiptong-connecHon wi „ , , . „
Kapp glvea In the folloiAnE table the beat practise sa to uignlar dli-
DTNAU08 AND UOTORS.
•>t™l«.
AnBul«dl.tanoBbetw«i.
bnuhoi.
.Degreen.
Degree..
D.gr«,.
D.«««l.
D«CTM..
2
180
«
«0
<
60
ISO
B
K
IX
10
36
106
160
W
30
90
IW
14
».T
77
US
160
le
2i£
ei£
111
IH
18
to
100
IW
160
ao
«
M
136
Iffi
^
Fig. 17 anoUier mapk u naed wIUi ■ gTeftt«r number ol pt
Fio. le. TuD-path Uultlpalir WinJlngx. Fia. IT.
Both ol the nbDve eunplea are of the Irmg-ctmntcliint lypa- In the it
(wniucfion type the fonunU for determining the Dumber of the eoU la
and Fig. 16 ia • Muaple diagram of thli Ijpe.
ARUATURES.
Pio. 18. BhDrl-40Dneet[on Tiro-pntli King Winding.
tn order tluU th« E.IiI.F.'i gsneuteil In the coUii of ft drum knnatan lattj
teln UM*une dInBllon. ttli neCHHur Itmt thet*D sldiH of «uh coll be la
* -■ desof the..::.
II bipolar maoMiua, and part
li of oppoalte poUtitT. and thsretora the aides of theooilaaieoonDected
— ---^-^Tonheflore; direc '— ' ■-' — "' '
d[ the multipolar type.
no, 19, Bipolar Dram Winding.
Tbe dnua vlnding la wholly on the exterior of the sore, FIb. 19 Is a dln-
■rain of a bipolar dram vlBdWopa nuoolh core ; the dolled Imce Indicate
IhecroHing* of the Tiros orer the rear head of the core. Dram windings
are moatlT of the tvo-lajer type, of whieh P^g. 10 J« a dlaarua; wltli a
(btted core, the oumbered conifac tors would lie within thesloti. In this
diagram eacfa pair of condaclors harlng niimbcn dilferlng br IScompoge
the twi>"(ldas" of one coll, and are therefore Integral with eashotbet.
DYNAMOS AND MOTORS.
nsrnl tTpea of drum wlndinjE; Up fti
s dlitlu|[QfBblDg tensB. Blpolu- machlue* ueoenkillr
FlQ. 20. Jllpolar twu-liiyer druni wlodluc.
Flo. II. Two-pnth single fonr-pols winding
baTelap-soDiiBctedirliidliigg. In mal tl polar mnobl nee the two "alda" of
eiwh coll tn liwuted n dlstsnce snart approilmiuelv eqatl u> the pal*
pUph Initsad of on oppoKite sides of the core (lee Fig". 21). TUa proporSeo
of ■rmatnre olreomlereDcs apanned bjr eai^ coil li preferkbly > trifle 1<m
ARMATOSES.
tkan the pals nltoli ; for > toothed amutim t&a nmnbar of taatb
by <ach ODil ■Eould be egnal Ui A'l — p ~ xi . llA', — p\t% whole .
zi = li l( U Is ■ mlied!^iiumber.:n = thelTMUoaKl putorl + th
U ihoDld aeldom SMeed 2 in ui j sua.
Alllap vlndioa have Jt m parallel paths. A multiple' vritLdlbg
of (vo or more dutlDct vlndiD^f the couducton of wlilch are am
tt eaaunntator aegmeuta aHembled In a amgle comiautatc
Wm. SZ. Bii-path alnile
ITJJ. J3.
_ I
tiare an; eren number of narallel patha ^
net polei. within practicaJ limits. The ■
if aafle and method of connecting thorn. W
>f onlle (and commnlacor segmcnli^, noni. \
The nikllar Talne of >■ la preferable, bat choice betwMn the two la tun-
■ ally detennlned by the oholie between the r--'" ' • -'-■••— "
■■ + 1 and m haTB a common f«ct.>r. the w
I aoiUp'--- ■•-- - -■-- '
detenulued by the choice between the reHultlng cljuseaof w
.■ 1 and m haTB a common f«ct.>r. iho winding will be of tho
inldplei tn>e ; If not. a aimpla waTe-eonneoMd winding will It
In slotted armatoree the niunh«r of conductors must be a multiple of the
DYNAHOS AND MOTORS.
ng. IS !■ k dlasrsm ot & two-pUh trtplsi winding, i^., thrM tvo-pal
IndtDg* HDUMted In piirallel br the briubsg. II b mathenuUcitllT U
IhItbIsdI of k alHgls ■Ii-pBth winding.
-hiSti
Fig. M (hmn dl>c'*''i<'»tl<'*llT tl'> chanoterUtla ot the oaiul tw»«al
Mure wlDdliig died on itreet rallwsy motor*, In which there mra thn
■ M muij eoUa M there ue alote. In thi* oHe n = 0.3S Ukd fa = "
ARMATURES. 349
tmm mmtrmmtU GIvcvite im H^ymmammB.
IMfBenltT htm been experienced in the operation of Urge multipolar direct-
nrrent mAcblnes with parallel wound armatures, owing to differing mag-
iBtic itrenfftba in the polee. The potential generated in couduoton under
At pole differed from that generated in conductors similarly situated under
■otoerpole of the same polarilT, the result being a slignt difference of
ptentiai between brushes of similar polarity. This caused currents to flow
DEcm one brush to another, and from one section of the armature winding
\» anotheTjattended by wasteful heating of conductors and sparking at the
This difficulty is obviated by the Westinghouse Electric s Manih
betwing Companv by the following method of balancing :
A nnznber of points in the armature winding corresponding to the num-
Wr of pairs of poles', which are normally of equal potential, are connected
W leads through which currents may pass from one section to the others
vtth wliich it IS connected in Darallel. The currents are alternating in
cksmrter and lead or lag with reference to their respective EJd J'.'s.
r thus magnetize or demagnetize the field maimets and automatically
[see the necessary balance. This method of balancing is also of advan-
Ib eliminating the sparking at the brushes and the wasteful heating.
ik occur when an armature becomes decentralised, owing to wear ox
tte bearings, or to other causes. When an armature gets out of center the
air-g>p on one side is greater than the air-oap on the opposite side. The
fdoitlal generated in the coils — if the anuMure has the ordinary multiple
winding— will be much sreater on the side haying the smaller air-gap than
that generated under poles of the same polarity on the opposite side. Con-
isqaently . a current correspondinff to this difference of potential flows
fhmigh the brushes from one section of the winding to another. This flow
of eurrent will act the same as if two generators were coupled rigidly on one
■kaft and the poteutial of the one raised above that of the other. The
Bsehiae lunring the higher potential would act as a generator, and the
otksr would run as a motor. This, of course, would result in bad sparking
and the burning of the brushes.
Bj the use oCthe above balancing method, however, the armature could
ke considerably out of center and no injurious results occur, as the balano-
isg ettrrents flow, not through the brushes, but, as explained above, through
9«d*Ily provided connections. In addition, the currents in these conduc-
tonare alternating currents—'* leading" in some coils and ** lagging" in
othen— a fact which enables a relatlveqr small current to balance the oir-
eoitifffectlvely.
The temperature an armature will attain during a long run depends on
Hi peripheitd speed, the means adopted for ventilation, the heating of the
Mnductors by eddy currents, the heating of the iron core by hysteresis and
sddr currents, the ratio of the diameter of the insulated conductor to that
of its copper core, the current density in the conductor, the radial depth of
vioding, whether the armature is of cylinder or drum type, and the amount
asd ebaracter of the cooling surface of the wound armature.
The higher the peripheral speed of the armature the less is the rise of
temperature In it. Mr. Esson gives, as the result of some experiments on
iZBiatures with smooth cooling surfaces, the following approximate rule :
iSr(l + 0^)0018 V) "" «S'( 1 + 0.00060 K') '
vkeref^ := difference of temperature between the hottest part of the arma*
tore and the surrounding air in degrees, Centigrade,
Pj^ = watts wasted in armature,
5 = active cooling surface in square inches,
jy =: active cooling surface in square centimeters,
V = peripheral speed of armature in feet per minutei
V = peripheral speed in meters per minute.
r
350 DYNAMOS AND MOTORS.
The more ef&cient the means adopted for ventilatlnff the amuitiiTe ■
cnrrentB of air, the smaller is the temperature rise. Some makers lad
spaces between the winding at intenrals, thos allowins the air free mm
to the core and between the condnotors. A draught of air through tbe^
terior of the armatwe assists cooling and should oe arranged for wlie
possible.
For heavy currents it is sometimes necessary to subdiTide the oondi..
to prevent eddy currents; stranded conductors, rolled or pressed hydrai
ally, of rectangular or wedge-shaped section, have been used. Such
division shoula be parallel to the axis of the conductor, and prefei.
eifected by the use of stranded wires rather than laminie. Few armat
conductors of American dynamos of to-day are divided or laminated fni
degree whatsoever. Solid copper bars of approximately reotangalar eiu,
section are often used, and little trouble is found from FOucault oarrenlfc^
Mr. Kapp considers 1.6 square inches (9.7 square centimeters) of c<
surface per watt wasted in the armature a fair allowance.
Esson gives the following for armatures revolving at 3000 feet per mini
P^ = watts wasted in heat in winding and core, J
S = cooling surface, exterior. Interior, and ends, in square innhij
S' = cooling surface, exterior, interior, and ends, in square oeflij
meters, ^
^^ = temperature diiferenoe between hottest part of armatareMl
surrounding air in C^.
Then 0^^±^ or ^t^.
S ^
Speclfloatipns for standard electrical apparatus for XT. S. Navy sav. "St
part of the dynamo, field, or armature windings shall heat more than 60° M^
above the temperature of the surrounding air after a run of four honnsi
maximum rated output." -««*• -»
According to the British Admiralty specification for dynamoe the tear
perature of the armature one minute after stopping, after a six hours* rS,
must not exceed 30° F. above that of the atmosphere. In this test the thZ
mometer is raised to a temperature of ac F. above that of the atmosphsn
before it is placed in contact with the armature, and the dynamo oomnlifli
(or does not comply) with the specification according as the thermomei«
does not (or does) indicate a further rise of temperature ^^^^^^^
The best dynamo makers to-day specify 40^ and 46° 6. as the maximum
rise in temperature of the hottest part of a dynamo, or BS® If the t«mi>em>
ture of the commutator surface is to be measured.
In many direct-current dynamoe having no special devices for rereraiJig
the current in each armature coil as It passes through the " commntaHS
■^5i®» li' *■ necessary to rive the brushes a forward lead so that the raj?
nettc fringe from the po^tip toward which the coil is moving may induce
*?ir'?-^* *" ^°? *^" *°^ reverse the current. In motors thebrushee si»
shifted rearward instead .of forward, the polarity of the approaehlns sole'
tipbeinff of the wrong sign. * *^
With the forward lead Sven to the brushes the effect of the armature eu^
rent is to weaken and distort the magnetic field set up by the field m^g.
nets ; a certain number .- depending on the lead of the brushes— of thesr*
mature ampere-turns directly oppose those on the field-magnets and rendsr
a somewhat larger number of these ineffective, except as regards waatltf
power ; the remaining armature ampere-turns tend to set up a magnetic fleM
at right angles to the main field, with the result that the resvdtant fleM
Is rotated forward in the direction of motion of the armature, and that ths
field strength is reduced in the neighborhood of every trailing pole-pieoe
horn, and is increased in that of every leading pole-piece bom. When,
therefore, the brushes have a forward lead each armature section as It oomef
under a brush enters a part of the field of which the strength is reduced bf
DraECrr-CtTRKENT UOTORS.
353
^
i =
(LordKelYin.)
andP =
vlwre
If =r moment of couple on axis,
Pz= preesure on eftcn bearing,
W = veiffht of armatore,
k ^ nuiiui) of gyration about axis,
Sir
0=? ^ w4 = maTimnm angular velocity of dynamo in radians per
■eeond due to rolling of ship,
A = — =: amplitude in radians per second,
(Radian is unit angle In circular measure.)
d =r degrees of roll from mean position,
T rr periodie time in seconds,
M = 2 m = anffular velocity of armature In radians per second,
n = number of revoUitionil of armature per second,
i = distance between bearings,
g = acceleration, due to gravity.
Note. — On applying the above formula to dynamos, where IT, k, aii<^«D
sre great, it will be f aqnd advisable to place their plane of rotation athwart-
ihips, in order to avoid as for as possible wear and tear of bearings due to
t^ gyrostatio action.
The eounter B.M.F. generated in a motor armature is given by equation
(1). This E.M.F. is equal to the E.M.F. applied at the motor brushes minus
the drop in the armature winding and connections ; consequently, the speed
of a motor la
B.t>.m. = '»<^''-^-")^'» (4)
At no load, the drop in the armature circuit is so small that Sw — ImR
my be eooaidered equal to £«, for the purpose of computing the no-load
(6)
The torque of a motor armature, in pound-feet, is
r=ii7*^«f-pi<r" . . .
Motors for operation on constant-potential circuits are :
Shunt-wound, for service requirfiig practically constant speed and im-
poses small load at starting ;
Senes-woond, for starting heavy loads from standstill and running at
apeeds inreraely varying as the loftd ;
Compound-wound, for starting heavy loads and
numtag at nearly constant speed.
Differentially-wonnd, for starting under light
mads and running at strictly constant speed.
(This type la not mneh used now.)
The remarks concerning dynamo maffnets, ar-
iMtareB,ete., apply also to direct-current motors.
The magnetiaatlon curve may be obtained by drfv-
mg the machine as a dynamo ; or it may be plotted
iFom readings of field excitation and armature
Bpsed ; in the latter ease, the curve will be the In-
▼ene of Fig. 1, as indicated by Fig. 25.
Brushes on a motor muRt usually be Set hack of
rae neutral point, or with a ** backward lead."
TUs tends to demagnetize the fields, and as weak-
Ming the fields of a motor tends to increase the
^•ed, the increase of load on a shunt-wound
>K>tor tends to prevent the speed falling, and the shunt motor is very
Asarly self-regalating.
i
Fio. 25. Magnetization
Carve of Motor.
DTKAUOa AND UOTORS.
I con^enble
H. Ward LMDud Inveuted tbe method bLuwu
mo«t Biaallant mnlti, Klchough to some eiieat en,
•fllolaDt.
Tba drlTliig motor, or ntbar motor wlilali It li viBhsd to oontnd, la p
Ttded vlth a Mpuately aiclled flald, vblob sMi b« TBiied bj IM rfaeottM ^
prodace an; rata of apeed, from just turnlnc to the full ipeed of irhleh %
mar ba c*pabla. Corrent Is supplied to lla Knuatun from a s«pankt« f ~
enlor, aud bj tujIdk the aaparatel]' exalted fleJd of thlasenari '
amoont of eucreot lapplled to the motor armature can be Taried at
the torque Eherefore cbangsd to suit Ch* clTsumitanoei.
Thegsnerator is driien at ooDatant nwed bj direct ea —
which get) lt« c
Fig. 26. Leonard's Sntem of Hotoi
BtfoT'"
entoraoppllM ODirent for i
Bt rerenliu tba flald of the earn
reversed, andlfaerefoTe so is the direc
Fig, 27 showi the Leooaid BTstem ai
Tkrwe-irir* SjiMBa far Tarlab
OmlttlBf sraaes, street rallwajB, holiits, and otJier i
{I) Machines requiring . .
fans belong to this class. Tbe poi
v»rj rapldfj -- "■ •" '-—
Taiiabla apM
GTMalng Kith tbe spaed. Bloi
w the speed iBcreaset, i
UDh eervlae. However.
<2) Machines
Is usnall; Binml'
IDUed for ^e machine J
bould be axaroised In seteeuDf
rarlatlob required Is usoaln
idard motors od a single nt '
„„„.j jfl nomiHiund-if Dund aud tb ~ *
The speed variation n
■eterably b.
id aud the apeed
d blo'
equlred for such aervlea
of tba shant fleld tEw-
_.... _HaairlndlnKtBe«peclsllT
ntlng the heavy fluctuatlona at cvl-
- oonptant speed motor In >
PRACTICAL DYNAMO DKSION.
355
rk beeawe « eoaatant speed ftt any point on the controller !■ not
{^ Machines requiring approximately the saoie maximum output at any
iMd, or a torque yarylng liiTersely as the speed. This class includes most
tthe machine tool work where automatloauT constant speed regulation on
notch of the controller is especially desirable. It is, therefore, neces-
ta> ose a shunt motor haring good inherent regulation.
C>««enit«r.— The stanoard Edison three-wire system for general
ition consists of two 12(>volt generators connected in series with
I awtral wire brought out from between them. A single generator of the
rell Toltage, with a motor-generator set of sufficient capacity to carry
I BBbslanced current, is used in many places. Still another system con-
I tecsdlT of a standard direct-current
ntor designed for the maximum
fSfoind EJi.Pr having collector rings
•osseeted to the armature windinc lile
atVMhsM rotary converter. Theleads
ftsnttese rings are connected to auto-
tmrfarmers or balancing coils, the
■iddle points of which are connected
to tiw Beatral wire. With no external
i^erieM whatever, the neutral wire is
i ttu maintained at a voltage midway
! tstvtea the outside wires of the system
|M» Jig: 28). These generators may be
1 9*nted in multiple with any standard
! Itne>vire i
system, whether it consists
«tyo machines operated in series, a
■BfleToltsgeceneratorwith a balanc-
iig wt or a double commutator gen-
mtor. Any standard single-voltage
ijitimmay be changed into a three-wire system by adding collector rings
to tk« generator ana using balancing coils to supply the neutral wire.
Pm ACETIC AX. lOmtAMO l»KSI«ir.«
It li nis to follow the rule of using bipolar fleld-magnets for maehlnes of
lulovttts or less and multipolar magnets for larger machines.
For eommatation reasons the current passing anv one set of brushes
Mould oot exceed 260 amperes ; this gives a criteiion of the number of
Cka for maehlnes of 260 amperes output or more. Lap windings should
ved on such machines. Then
1» =
0.006 Tm
m
(«)
The nomber of poles on machines having wave-connected armatures is
wemlned by commutation considerations oniefly ; more than six poles are
Mdomnsed.
The best construction Is a laminated magnet pole with extensions at the
w-gap end. bolted to a cast-steel yoke. I^rly good results are obtained,
jl^ever, with cast-steel poles. Laminated cores, cast-welded into either
ina or steel yoke and provided with cast-iron shoes embracing the ends at
tte sir-cap, give excellent results if the east^welding is properly done.
^fom the ratio of air-gap length to the width of each armature core-slot
^^P^niag is maeh less than 0J(, the pole-face should be laminated in order to
Vvftn excessive eddy curents in it : otherwise it may be solid. A cast-iron
poleehoe must not cover the end of the magnet core, but should surrotind
n ud serve merely as lateral extensions ; the cross section of the core
■hould be slightly reduced where it is surrounded by the pole-shoe.
• Cecil P. Poole.
i
356 DYNAMOS AND MOTOB8.
The E.M .F. generated in the direct-oorrent armaiare ia, from eq. ^),
P q W
which reduces to
B = 0.06236 IhWp^Bf-^' ■'•pm. VT* -^ q.
The output In vatta is Pw = E» /«, which for preliminary puiposas
be considered the equal toEuq; whence
P« =0.06236 ZV FF>V' Bp««'^« r-P>ui- 10-* ....<!
For eooaomioal use of material, the projected outline of a pole-f ae« alioiH
be square, so that the width parallel to the armature shaft should appatin
matel; equal the chord of the average polar are: whence Wp shoaM
be= Z>^ dn (180 V* -r P)- For moderately high-apeed maohinea, ^ mmj bi|
Uken at 0.7 ; for slightly lower speeds, at 0.72, and for slow-speed nuielkliM^
at 0.75. For reversing motors it ia beat put at 0.6606, except aeries-wouaa
reversing motors ; finr ^ese, let ^ == 0.7.
Representing sin (180 1^ -ri?) by li^, page 371, results.
The average magnetic density over the pole-face ranges from 25/Mn t^^
60,000 lines per square inch, according to the designer's method and the
of the macmne. It is rational to make B^=c x Dp^^yO being aeoeffiei
varving according to the type of machine. For constant^tential drnai
and motors for general service, 28,120 is a suitable value for c ; for annnt
compound-wound reversing motors, 33^60 is appropriate, and for rnvries t9^
versing motors, 36,620.
The permissible number of ampere-conductors around the armature paifr
phery ranges from 1200 to 2200 per inch of armature diameter. For
chinos designed according to the method outlined herein, it la
practice to apply the formula:
The values of kt are as follows :
Dynamos and motors for general service, ka = 679.
Shunt and compound reversing motors, ke = 564.
Series-wound reversing motors, ke = 678.
From the foregoing equation an equivalent Is obviously obtainable for
UHe ^, and substTtutmg tliis and the equivalents for Bp ^nd Wp prerioaaly
obtained, equation (7) reduces to the following two :
For all machines except series-wound reversing motors :
„ tA/>p*-*r.p.m. ^
^-=—100 «
For seriea-wound reversing motors :
i>» = 0.013 Au 1V> r.p.m (^
For belted machines which need not have any particular rate of speed, as
economical rate is
8500
r-P.m. = jy;^'
Considering Dm and Dp equal, which is allowable in preliminary " rough-
ing out," ana substituting in equation (8) the above equivalent for r.p.m.:
P. = 85 JtM A>*'" W
Araaataire Iletaila. — Gore disks 25 mils thick mav be used in moat
armatures ; only those In which the core is subjected to nigh rates of
netic reversal need have thinner disks. When p x r.p.m. exceeds 3000, it
advisable to use disks 20 mils thick, or less ; wnenp X r.p.m. exceeds 4000,
15 mils should be the limiting thickness. The final criterion, however, li
the eddy current loss in the core and teeth.
PRACTICAL DTNAUO DB8ION.
367
I HaTlng a means of determining the pole-f aoe width parallel to the arma-
twe abitft, the length of the armature oore follows within dose limits.
Ihe armature oore ahoold extend beyond the edges of the pole-face at eaoh
tad by a smaU amoont^not less than the aix^ap length, and preferably
15 times the air-gap.
Armatnre cores more than 6 inches long should haTe Tentilatlng duets
■ot ksB than | inch wide at interrals of 2# to 8^ inches. The exact duct
I vidth is usually determined by the amount of steel required paridlel to the
•luf t in order to keep the magnetic density in the teeUi within suitable
Umits.
The" nominal " magnetic density at the narrowest part of the teeth should
be between 140,000 and 165.000 lines per square inch of net cross section.
The "nominal *' densitr is that which would exist if the flux did not spread
bsjond the geometrioai contour of the pole-face In passing from the latter
l»tks armatore, and if all of the flux passed through the teeth ; that is,
,- ,^ — = nominal density at tooth roots,
wa = 0J» ( IT* — yentiUting ducts).
Is Older to obtain dimensions that will result in a ** nominal " density at
tbe roots of the teeUk that will be within the specified range, the number of
teMh (sad slots) may be approximated by means of the formula
wDt-
At =
Vfm
(11)
Themmber of teeth must, of course, be an Integer ; If the result of eq. (11)
■booU be a mixed number, therefore, the fractional part should be discaraed
U it ii 0^ or lees ; if it be more than 0.8, the next higher integer Is to be
taken as the number of teeth. The net measurement of the armature iron
psnliei with the shaft must then be corrected to satisfy the equation.
«^ =
ki
Us value of Ai for all oases is
9D*^9lf$
(U)
When the armatore eonduetors are round wires, the size of the coil slot
if determined chiefly by thesise and arrangement of the wires. Form-wound
%
W^
J
Fie. ao.
^
uid Mparately-insnlated ooOs are generally used, so that the coil slot is
^ uY?^^ of one of the shapes shown In Fig. 29. the slots a or ft being used
l^eubliidlnfF wires are employed to keep the wires in their slots, and one of
•*• others Trtien the colls are held in by wedges. Two-layer windings are
2™Jost iarariablT used in this country. Fig. 30 shows two half-coils
araesst" in eaoh layer, each coil haying three turns of wire ; this makes
358 DYNAMOS AND MOTORS. '
the toMl QuDibtr of soils twice tba nunibar of ilota. Tig. 31 alioiri UuM
half floila " nefllwl." witb two turrti p«Tcolt ; thfaglrfle thi^ llnrn a« vumf
eolliu (bare are Blots, "tliraeeoUe per slot." iirBaitremelTobtwittoiiiilA
to '■ neat " the eoile, but MmetimeB unaToLdsble when round wirw lue iwei.
Table II, p. 372. glvei elot widche and deptlu suitable for rarions Brran|»
mania ot round eonilur ton dniwn toB. AS. noge, bavsd on two-lnver wtnd-
ingsuid the tusulatlou Indlnted In Fig. 39. TheindlTldnal ooUa mto tnwfptt
Fid. SO. Pio. SI. Fig. 32.
cb ralea-ti
verlng of
icb ralea-treated prcM-boud, each trorat el
Sb oiled tape, h&iriapped,
and tbe slot !■ lined with a troogb of a,D2-lDah mica-treated preas-board.
If tbe presB-board Is ■ '■ -•'-■- - - --
coils ara dipped and bal
tlon win be adequate fo
. .. >t Is lined with a troogb of a,D2-lDah mica-treated press
If tbe presB-board Is well Tamlsbed wltli Insulatlne corapoimd, a
ra dipped and baked before being aseembled In the slota, this
not be less than I of Its depth nor >non
than i the depth. Tlie depth ot the coil Blot, Cor annatnra ot IS InehM
diameter or orer. may be eitlmated for prellmlDary pnrpoeee hj meuu at
•=.+^ „
Appropriate trial depths for (he ooil alota at imaUer cores are (tven bf
Table IILpage 3T1.
Table iK ^ge 3T3 eIth empirleal bnt pradtlcal trial mines for tlie mini-
mam allowable numbarof armatore cntln, andTabla V, paf* 874, gives Talne*
for the mailmnni allowahla number ot turns per coil, for nse In prellmlnatT
domX eioeeded without riBk of Bparklng at the bnUbea.
Table VI, page 376, gives trial values for armature oondnclor sins ; the
actual allowable enrrent density in the conductor!, boverer, la determined
bT the heating at the armature.
AFMStBiw Iassvs.— The total losse* In the armature should oc*
exceed the value which will give a temperaiura rlne
The relation betveen lont watts, radiating Burl
and temperature rise Is. tor talrly well ventilated ai
Held magnet trames, approilmately u lollows :
peripheral velodlT
ires in ni>ik.«DOlOHa
and allowing a riae ot 7D° this (
O.IF.fl-
PRACTICAL DYNAMO DESIGN. 359
The roMoo for laklng P*^ insteMl of Pj^ m the eritarion of heftHag to
tbftt the projaetlng parts of the winding do not act effeetively in radiating
0M \%!emX produced by the core and teeth loasee, although their radiating
■■rf ace ia always ample for the iV ices In them. Since they are not included
in the radiating surface, the loss in them is not included in considering the
With round conductors, the watts lost in the embedded part of the wind-
li^ will be, with sufficient accuracy,
if the condootors are rectangular In cross section, -z — must be substituted
for ^ in this equatioA.
Tlie kMsas in the armature teeth must be estimated separately from those
in the body of the core, the densities being widely different in the two parts.
The general formula for hysteresis loss in either part of the core to
Pk:^4IMchvp r.p.m. 10" »
and the formula for eddy current loss to
P« =r 4 ktvp^ (r.p.m.)« 10~«
fai which kk to the loss per cubic foot of iron due to hysteresis, as giren in
the table on page 100 and k* the corresponding eddy current loss as gireu in
the table on page 100. It should be borne in mind that although uie con-
ftanto taken from the tables mentioned are based on losses per cubic foot of
iiOB or steel, the Tolume of iron or steel represented by v in the equations
it fai cubic inches. Combining the three equations Just given, the total low
ts be considered in estimating the heating of the armature is
Pa' = FF« a; ^ +P r.p.m. JO"' [48 {vmkk* + vt km)
-\'OApr,p.m,(vmkm-\-vik0ty] (15)
In order to allow for the crowding of the magnetic flux toward the slots
the eroes section of the armature core body may oe taken at 0.8 of the actual
eross section, making the effective volume
o« = 0.2 V (ZV — Z)o>) tr« (1^
and the effeetlTe density will be, accordingly,
^=0.8(Z)»-2>o)tr. ^^''^
For computing the probable losses in the teeth the following relations may
be assumed without appreciable error :
active
per
> teeth) /2*^« . ^\« .
pole }=lr5 + pj^''
avenge width of each tooth = (T 4-2 0 -f 3 ;
and since (t -f 2 0 -f 3 = [v (Dm — 1.33 A) — A^« s] -f Nu and the average density
in the teeth, for the present purpose, is equal to tne flux per pole -7- active
teeth per pole x average cross section per tooth, the average density will be
Avg.BT=.2ifc»8 ^\ ' ... (18)
(^ + 1) [ir(D.-1.3A) + J^i*]w-
The volume of iron in the teeth to
WsTj/A.*- j2>i»-A*iVil w. (19)
PRACTICAL DYNAMO . IXE8IGN. 361
ihovn vere plotted by Heesra. Eaterleln and Keid from t«8t0 made on a
ttige number of actual machines.
In estlmatins before hand the eflElciency of a machine, the loss in the pro-
Jading parts <H the armature windins must, of course, oe considered. The
•etuaT total loesee in the armature winding and core will be approximately
P^*=. UN*^-\-p r.p.m. 10-' [48 {p»hm + wAaw)
-\-OApx.^.m.{vtk^-\-f)mkmy\ (20)
In a barrel winding, the length of each conductor ({«) will be practically
that glTen by the formula
<• = ir« + Aw (2>« — A) + 0.8 (1 -f A),
if the oanduoton are bent around |-inoh pins, as indicated in Fig. 35, and
Flo. 85;
lAsrvard palled out to span the proper number of teeth. Table Till, page
3RigiTes raluee of km for different numbers of poles. Each coil will project
Wjoad the armature core at each end about
^ <2Jb- A) + ii^ inches,
sad Ihe distance fit>m center to center of the winding pins must be equal
to
W*-\-hm{Dm — h) inches.
CoMHBstetor aad Br«ali«a.— The number of commutator barss
santber cf armature coils or elements, in practically all modem windings.
Tbit diiuueter of the commutator barrel must be kept as small as possible In
Older to reduce the friction loss at ther brush faces as well as to keep down
the eoit of the commutator and to fayor good commutation. From purely
MSfhanical considerations,
Dk > 0.06 X Number of segments (21)
lor Momatatioxi reasons and to keep down friction,
JDi> 10,000 -hr.p.m (28)
la flaalty rovndijig out the dlmenoloiui, tiie following relation should be ob-
Mned, ft possible,
*=^ <^
U|dn I thould preferably be an integer.
Xbe enrTSDt aensity in each commutator segment should not much exceed
'''^unperee per square inch in the horizontal part find 2600 amperes per
*4nare inch in the connecting lugs or risers.
The brush faces should be of such area and number that the current den-
fity at the faces will not exceed 40 amperes per square inch for carbon
broghai, 160 amperee per square inch for woven wire or gause brushes, or
i
362 DYNAMOS AND MOTORS.
900 amperes per square inch for leaf oopper bnuhes. Good areni^ fan
densities are 90, 120. and 100 amperes per square inch, respectively.
With pressures of 14 to 2^ lbs. per square inch of brush face, the effective
resistance of the brushes wiU usually be
Carbon brushes :
Copper brushes :
0.0125 ^
M
The total drop in volts at the brush faces, therefore, will be
Carbon brusnes :
^ - volts drop (M)
Copper brushes :
— volts drop (3«a)
90M
The loss in watts due to the friction of the brush oontaote with the com-
mutator Is
M Dk r.p.m.
H »
jbt varying aocordlnff to the brush pressure, condition of commutator and
quality of brush. The total losses at the brush faces, therefore, are
Carbon brushes :
Ah Dk r.p.m. ,/•*_„. ^,
te + 8"^ = ^ W
Copper brushes :
Ai Dk r.p.m. J^ _
— H — + §r2i=^ ^J
With ordinarv grades of copper and carbon brushes and a commutator in
reasonably good condition,
680
~ brush pressure in lbs. per sq. inch'
The maximum efficiency is obtained when the two terras of eqe. (26) and
(26a} are equal, i. «., when the friction loss equals the P R loss.
Tne temperature rise of the commutator \nll usually be
86 X total lost watts ^ ^^
= » (26)
If the lugs of the commutator segments are of considerable length, the
rise of temperature will be somewhat less than calculated; on the other
hand, if the commutator and brushes are not in good condition, the loases
will be considerably more than given by eq. (26) or (25a) and the tempera-
ture rise win be correspondingly greater. The temperature rise should in
no caae exceed 76^ Fahrenheit, and it is preferable to keep It down to OOP or
70®.
The dimensions of the brush face transverse to the commutator segments,
is determineil almost solely by commutation requirements, and these in-
volve so many widely varying factors that no hard-and-fast general nda
can be laid down. For machines of ordinary types and fftlrlj large sixes —
100 kilowatts and over, say — the span of a carbon brush may be roughly
estimated by means of the formula
PBACTICAL DTNAHO DESIGN.
TUi lonnBlB vUl sppl; vlUi infllcli
iwiliilin tb« mlng, for % ilrwi tjim v uoiku, u> iiki
duomlnator of ths brmoketAa (rmctlon. For toT«n]ne m
tipe. (or ujunple, it b ISOO. ud for aiiul], ■tLiuK^vound i
tliBul dfalfu, ft iMBgtt from SOO to 1000.
Alr-^kmf. — Tile mschuilcal slr^np, trom tba pole-fi
tkeumUureueth, ibonld be made the
thM ilreai bj the fonnnlm
for >11 pneUokl work bj
of th« oo«flelont In tbe
ling molon of « certain
nB,UtlMfoni
micUne ii to r
HDldbeAlnch
nadiUiinaer U
Iktphiiof .
pTvnbury
[hs bwla of thli uctloD. Bea"CheoklDg op
iwlovlj described, Ihe aTerafo chord b^ng oqiul i
pBiUel lo the ahart being prefenblT equal to Uie ch<
II ._ii.i — 1-1 — 1 .I. Intetpolar edge*
3 jU /)> and Ihe wldtb
F^llj oblli
ha aimatnre slota. A common expedient tor avoiding Ihli par-
lo round the Inlerpolar edges M In Pig, 36, or to make them
rwlth npoot to the aiK of tha machine, u In Fig. ST. If
vKbont ahoe* are DMd, (he eonnn at alternate eheeli of
I
•MihooldbeentswaTaalnFIg. tS f >
*- Id I^. 3«. for polar ■ilesair—
tv..___. 3f fh< '— ---
- in nf. w. lor polar ■itesalona.
ibtlanrth of the pola-taoe epan ihoald never exceed 2.6 I>,-^p; prMtl>
olnluaareglTan In the beginning of thia aeetlon (pageSM.)
Checlilac "r grgU»tiM»ry PI»«iiaal»M.— Before pagalngon to
Ibe Deld-mignat proportlooa, and proftrablj ba(or« taking up the probable
■"Batna Icnea, the prallmlnair dlmenalona ahoald beobaakad ap In order
atna Iceae*. the prallmlnaiT dlinenaloni
uka inre^Mt tbe dealred E.M.F, la o
—■ aolalling tl ' '
iia oeinaeaea np inoraer
able at the dealred apead
364 DYNAMOS AND MOTORS.
HftTing ascertained by meana of eq. (11) the maximtun niimber of coQ
sIotB allowable and adjusted the net armature iron dimension axiaUy W
eq. (12) the £ Ji.F. or counter KM.T. of the armature should be tested by m§
formula:
„ __ k^D^^Wp^N. r.p.m. IQ-* ^^
P5« ^
and if the E.M.F. is not what is desired, the armature diameter should be
changed to correct it rather than change the value of either Wp or ^ or both.
On the basis of the author's method, the E.M.F. is proportional to hj^^. if it
be assumed that the number of wires will increase or diminish in proportioa
to small variations in the diameter ; therefore, if the preliminary dinieB>
sions do not {dve the proper E.M.F., the correct dimensions may be clQeoTr
approximated by
Trial ZV-w xE ^ ^ ^ ^^
5^2P = Correct ly--;
the word ** trial" referring to the diameter and E.M.F. first obtained.
If the air-gap length actually adopted is not precisely the value given by
eq. (28), the pole-face density snould be adjusted to satisfy the equMion,
P^- p6 <"^
The values Of k* and kd are as follows :
Type of Machine: General Service. coST^e^g. ^^'S^'
!:•= 81 86 96
kd=z 1662 16B2 1831
The tendency to field distortion and sparking at the brushes should also
be checked (after correcting the armature dimensions and pole-f aoe density
as just explained)_before taking up the field magnet propornons.
pS is approximately proportional
-gap, and ii ilT* dr ~ P = Armature
nder each pole-face.
Arasatnre lt«ac«ioB sutd CoMHiBtatloB. — • In order to guard
against excessive field distortion the relation between the air4ap ampere^
turns and armature ampere-turns should be as indicated by the following
formula, for operation with fixed brushes at all loads :
Bfpa^lvl.Jr«^ (31)
The value of A> varies as follows :
In general service machines, kr n 2.8.
In ahuut and compound reversing motors, Jv ^ 8.
In series-wound motors, kt « 2.7.
The formula is based on the facts that Bp2
to the ampere-turns required bv the air-ga^
ampere-turns tending to distort the field under
Tne tendency to sparking at the brushes is proportional to the inductance
of each coil, the number of coils simultaneously short-circuited by one
brush, the number of coils in series between one positive and one n^atlve
brush and the current in the coil being commutated, and inversely pnmor-
tional to the length of time the coll Is short-circuited by the bmsn. The
inductance of the coil is proportional to the length of the conductor and
the square of the number of turns per coil. The following formula, based
on these considerations, is an excellent criterion as to the sparkleasness of
a machine :
(Fr« + 0.1^)<«t.n*^|r.p.m.lO-«-Z» (3^
The value of Kt varies as below :
Kilowatts of machine : Up to 15 30 80 100 600 1000 or over.
Kk= 80 70 00 00 40 86
Field MLmnmt. — Gores of circular cross section are most economical
of wire in the field windings, and a square cross section is next best In this
respect. The temperature rise is greater, however, in a round eoll ot given
P&ACTIO^Ii DYNAMO DBSIGN. 365
Miignfitiring nmrnr Ihan in a squure one, the oroes seotloii of the core and
lenifh of coilalonf the core being the same in both oasee. Bound ooila are
cnSer to windy and are nenally preferred. ^ . .
The length of a magnet core from the yoke to the pole-shoe or beginmng
of polar extensions, £«., the space available for windings, parallel to the
§ax path In the core, may be roughly estimated for preliminary Uying^ut
MfouowB:
jU = . ^^ ._, (38)
900
o.3 4pap\
V "^ UN.
The trial core length obtained by means of this formula will nsnaUy require
rwrteion in ordorto obtain the proper radiating surface for the coils.
Tkt nagneiie densUy in field-manciet cores ranges from 90,000 to IQOfiOO
lines per square inch for cast steel, and from 100,000 to 110,000 for sheet
itoel. The density in magnet yokes ranges from 3&,000 to 45}000 maxwells
periqiiare inch in cast iron, and 85,000 to 05,000 for cast steel. In railway
motonand others of extraordinarily light weight, the yoke density is con-
Bidenbly higher than in stationary machines ; the core density is also
Mmsvhat higher, bat the dUference is not so great as in the yoke.
The density is not uniform throughout the length of path in the core, nor
bit 80 in the yoke, but for conyemence the maximum density is assumed
to eiist fhionghout the length of each path.
Lmkage of magnetic Imes between adjacent poles and between each iwie
ud the yoke surfaces makes the flux in the field magnet considerably
1
FlO. 40.
rMier tiiM^ that in the airgap. The relation between the magnet-core
In tad the air-gap flux is
TheTslue of r varies widely with different types of machines and different
liiM of a glTen type. Tot well-designed machines of conventional types it
■sf he assumed tentotively to have the values given in Table X. It is con-
lUerably higher for poor designs. In the absence of data from existing
■ashlacs ofthe type being desiened, the field magnet may be proportioned
on the basis of the values in Table X, page 870, tentatively, and the leakage
nMighl J cheeked up as follows:
Lay out to a rather large scale two poles of the machine and the corre-
■ponJliig portion of the yoke, as shown in Fig. 40 for a circular joke. The
nengelraisth of the leakage path between the uoper surface of the polar .
•xteSkm and the inner surface of the yoke wlU be about as indicated by M
the dotted line Z, and the length of the leakage path between the neighbor- m
tag polar extensions wUl be about as shown by the line Z,. The mean ^
^gth of the leakage path between the flanks of neighboring pole-ends is \
pncticaUy eqwOto the dtotance between the centers of the two measured
•long a cinr^ar arc concentric with the armature ; repreront It by Z,. 1 Je
mm length of the leakage oath between each Po\tP*2'**SS"^!^1™«S7fl„5
nriaceWng between «Mid» may becalled equal to Z. The maximum flux
fa the ma^t core will be approximately as given by the equation,
VleM-Manie* Kxcttaitloia.— In order to estimate ^^^o'^^fj^ *52
•wsltatton required by the machine, the quaUty of the Iron and steel to be
»
Aoipent-tumi p«r Incb of lausth
ir-gap of > dyiiamo U no load 1*
PRACTICAL DYNAMO DESIGN. 367
For a motor tbe flu is the same at fall load m at no load, except in special
Cises where a series winding is used in order to start a heary load, and ex-
e^»Ung series-wound motors. The maiimnm air-gap flux for a motor haying
to itart under a load is
^-^-inpiaN. ^
The full-load ampere-turns per pole for a dynamo or motor are ^-4- iV.
The ampere-tums per inch fbr the armature teeth will be the mean be-
tvcm the ampere-tums per inch required to produce the density at the tops
and those required to produce the density at the roots —not the ampere-
tuns required to produce the average density in the teeth. The approxi-
msts dmsity at the roots of the armature teeth will be, at full load,
and flie approximate density at the tops of the teeth will be
Ai tome of the flux passes to the armature core body through the slots
ind ventilating spaces, the aetual densities in the roots and tops of the teeth
an k» than the approximate densities given by the above formulas. The
aetual densities cannot be computed directly, but may be derived from the
niatioh between the actual ana approximate densities, which is as follows:
Br'=Br + 3.1i«A[^'(l+J)-l]
(40)
Sbee the fonnula cannot be transposed to solve for Br l>«oause Br *°<l/r
■re interdependent and vary at different rates, a table should be prepared
■bowing values of B/ corresponding to different values of /^ at different
ratioa of « -^ r and Wm -4- w. The preparation of such a table is greatly
fsriHtsted by first preparing a table of values for
Npreaenting this expression by Jb^, and thereby reducing eq. (40) to
B/=Br + *r/r («)
Table XI, page 377, gives values for kr for practical ranges of values for the
tvo ratios mentioned. From eq. (41) and curves such as those in Fig. 41, a table
of eorreaponding values for Br' <^<^/r ^ easily prepared. From such a table
the Tslue of /^ should be ascertained for the root and top of the tooth and
also for two or three equidistant intermediate points between the root and
Vofr* the average of these will be the working value.
The ampere^nms per pole required by the air-gap will be
r,= »^"" V . — r w
i
<»F>+»*.*.»(^+*»)
368 DTNAM08 AND MOTORS.
Table IX, page 37S, giTM TslDMot tt, »"> ^- *1 >>"■ tli«flo' i^l vltUn otdt
atrj natgtm. Ths coneUnt kn la Dierel; Ibe number wblch, mnlUiilisd b
tfae Blr^sp lenffth, fiTet the extent to Tbkch the atr^^p dimenBLon pai«I*~
' (0 tbe iban U luureMtil bj the boving OQtvud ot tti« masnatlo fliumpi
«
>
tog troin the t^le-faoe edgei to the umalure core teeth. The oonttMit ki l<
the proportion ot the pbytlcal Blr-up length. J, by vhl^ the gmp ts inenOMl
etfflctWeLy by the pbiBii^e of flux mto the iJdH of the ftrmmfnre cere teeth.
Thlshu been uken from Mr. F. W. Carter'* article Id the Bledrical WarU
and Engincrr tor Nov, 90, igoi.
The THlue of F- csunot be predetermlQed aith any approach t« aoemraey
luilflfle one baa data from exlitlna niaoblnee of oorreeporullng tjpe and oD^
pnt. The following empirloal formula vlU eerie bi eitiniaM nnghly tha
Talue otJ'-{-Fr for modern Amerloan dynamo* and non-rererdng moton :
^
PRACTICAL DYNAMO DESIGN. 3g9
J-+^.= <^-^'"^-»»>*'^'+i/i^«+(^-»*^^'V . . (48)
iy»«T«»ing motor., ^___1 ^ ' '
F+Fr= J^tj^ /aejfr*;^ (4aa)
The no-load excitotion of a ahunt-wound dynamo need not be predeter-
Dined. The no-load exeitation of a oomponnd-woimd dynamo is
Tlie ampere-tnms of the MTeral parts of the mag netio oirovlt are deter-
BdDed M in the case at full load, taking into aooount the difTereneee in
magnetie density in each part.
iuter tiie first machine of a giren type has been constrnoted, with the
ezetttUm of the fleld-magnet coils, it should be tested with temporary
fixdyng ooils ; the resnlts of these testa should be taken as the foundation
of the magnet coil calculations.
rield-BEaiC**^ WIb^Ibm. — The field winding of a series or shunt-
vmind dynamo must be capable of giying the excitation required at full
losfd.
The field winding of a shunt-wound motor must give the excitation re-
quired at the proper full-load speed.
The field wmdmg of a series-wound motor must gire the excitation re-
quired to produce the starting flux, •,.
The shunt winding of a oomponnd-wound dynamo must glTe the exoita-
tka required at no Toad ; the series winding must gire the difference be-
tween this and the exeitation required at full load.
The shunt winding of a oompound-wound motor must gire the excitation
required at normal no-load speed ; the series winding must give the difiTer-
saea between this and the excitation required to produce the starting flux,
Iha surface of any field magnet coil on a dynuno or motor of open con-
itmetion (non-enclosed frame giving the external air free aoceaa to the
vindin^), should be
IfO^^ (44)
r bebig the resistance of the coll when warm. For enclosed or poorly Ten-
tilated frames, the coll surface per watt per degree of temperature rise
mait be determined by trial ; no general rule wUl apply. In all oases 0/
ihould not expeed 70^.
The proper slae of wire to be used in a shunt field coil is approximately
^ _ ^M(g + irA) ^^
Should the calculated ralue of cP not correspond with any standard sise, the
aearest standard slxe should be adopted and the depth of the winding ad-
Iwted to suit it by transposing eq. (45) and solyiug for A, thus :
d*e
£,^— («)
ir
Bee also Magnet Windings, page 112.
The minimum number of turns per pole for the series coils of a com-
poand-wonnd machine is
Turns =
Iw
or
^+ ^; - ^'* (long shunt)
(47)
»
DYNAMOS AND UOTORS.
sot nceed OiXIIB tmn
lb per *4n[Mro ordluirllr ; It w\u ba fiiuIlT deCerniliMd kr
« per ■mpATB ftotiuil; canied b; tl
tbechnrnftrr-.f norrlM, Table XII, jmm y... ,.,_
dlnsry coiistHiit-potBDlUI dynrnmia, ■nd>rg. Wglrdi
'ton for genBral nerTice. Traotluu md nutonioHls »
I7 from ftiHa laluea.
A trUI pol&r bore, eq- S or 9 or 10.
TypoofurmiHurB wfndlnB: numborof pull
Numbar of polM ; eq , 6, for Isp-wonnd niM
Hatio of pole-fauB span : pols pitcb (#).
Mulmuin pole-f ue iridth (W,^bi. D,).
Alr-gsp, eq. 26; the Brmalnre dluneter fell
k Tri™i^^o( ooDductor, Wble VI.'
1
PRACTICAL DYNAMO DESIGN,
371
9.
Sixe of eo!l slot, based on number of conductors per Blot, either
Table HI or eq. 13, and rulee« <28 and « =- to— .
10. Possible number of coil slots, eg. 11 ; hence, total number of armar
tore conductors, keepixig in ylew type of winding, eq. 2.
11. Corrected poie-faoe density, eq. 30. «. .^ ,
12. Field-distorting armature reaction, eq. 31; if *> comes out too
■mall, the polar bore must be increased, thereby increasing the pole-face
dsnstty and air-gap ; then solve eq. 31 for A;, taking the nearest smaller
Tslne chat will lit the winding. ^ ^ ,». .* *v i^
13. Corrected pole-face width, by soMng eq. 29 for Wp; if the result
5 ** 23^ accept it ; if not, take a stiU larger polar bore, with the corre-
nondiBg air-gap, and start oror from Determination No. 11.
14. Net axial iron measurement in annatiure,eq. 1^ , .,,. ^^^^if^^
15. Groes length of armature core (= Wpf2lXo FTp + 4 1) ; ttie dlffer-
«DC8 between tWTand the net iron to be o«caPj«d by ventilating ducts^^^
18. Number of armature ooiU ; check by Table IV roughly ; a discrep-
SMyof 25% is not prohibitive. ^^ . «« »^ u »^ - «-
17. Diameter of commutator barrel, eqs. 21 and 22 ; Z)» should never ex-
QMd0.9Z^, andO.7 />• is an excellent limit: if the diameter comes out too
great, the number of armature colls must be reduced and the axial dlmen-
•ions of the machine increased correspondingly, if practical : if not. a larsrer
poUr bore must be Uken and the determinations revised from No. 11, also
rfnsingtheair^apbyeq.28. _^ ^ « ^ ^ «t
13. Complete commutator and brush dimensions, eqs. 25, 26, and 27.
19. Probable tendency to sparking, eq. 32 : if Kk is excessive, and the
tsms per coil cannot be reduced without entailing an unwieldy number ox
oaib, the polar bore must be Increased in, order to permit reducing the
lM|th of the armature core, the determinations being revised from No. 11
•ft«r finding the new air-gap, eq. 28.
». Armature losses with respect to heating, eq. 15 et seq. ; if P^' ^-
ewds the limit set by eq. 14, and cannot be brought within the limit by re-
doelng the hole in the center of the core, the ventilatinK ducts may be
redaoed sufficiently to accomplish the result ; if not, and if Wa cannot be
•sfBdently increased on account of eq. 32, the polar bore must be increased,
the corresponding air-gap adopted, and the determinations revised, begtn-
BlnfwithNo.il.
luvimr progressed this far, the remainder of the desiffn is straight work,
only a slight revision of the trial magnet core length beingprobaDly neces-
nrv to oDtain the Tniniiniim quantity of Aeld copper within the neatlng
lioilt.
VAJDMJB I.
Valvea of Im.
Poles.
^ 1= 0.066.
4r = 0.7.
^ = 0.72.
4f = 0.75.
2
4
6
0.866
0.5
0.342
0.891
OJ5225
0.3684
0.9048
0.5358
0.3681
0.9239
0.56S6
0.3827
8
10
12
0.2588
0.2079
0.1736
0.2714
0.2181
0.1822
0.279
0.2244
0.1874
0.2906
0.2334
0.1961
14
16
18
0.149
0.1306
0.1161
0.1564
0.137
0.1219
0.1609
0.1409
0.1253
0.1676
0.1467
0.1305
20
22
24
0.1046
0.QM9
0.0872
0.1097
0.0998
0.0915
0.1129
0.1026
0.0941
0.1176
0.1069
0.0979
i
DYNAHOe AND IfOTOBB.
Ill
3-1
«
I
3 111
9
I
■<«Ifl"I*,
„.
-""SssaxasKssa
i
3
1
1
1
1
1
1
1
1
"
: : : : :»3«iii»ss*«
=
:::::: :S35?>iiii!
S
■ '■ ■■S5S=5'i""^=5«
S
: : : : :5^s?si:i5«?
•
i!S:353S"*5''<'^^^'
•
3S53S'*5^"5???,.=.^^
-
|S«i!i;88*?fl?^Si^H??
-
?????!!,<wi?^,.s ; : : :
■«l6"!il.
— ""■•■ sssassassaa
1
3
1
■s
1
■8
-
.
-
: : : : :!?ss?>.ii!i^s?r!ii :
t.
: : : : :3S!i!*?«ii!iS!!ii!!i :
« 1 ;;^S«4li<;^S!>|Ii«!)3t!tS! 1
&
!j3SS!S!l?«Si5(!Sass!!I|i!
-
ssii^asajsaaas ::::::
18 911
a
...
"•"asHHsasaaaa
^
FRACTICAL DYNAMO DESIGN.
373
Trial Jkwmmtmrm G«ll Mot Depths.
Cora Diameter.
Slot Depth.
Gore diameter.
Slot Depth.
6
?
ft
1?
11*
S
H
Ift
12
i?
k
If
15
1?
Vvtal ▼•!«•• for MfniaauM Vwamh^r •f Amature ColU.
The nnmberB in the table are Talaee of ^^ X -^KW.*
KW.»
125 TOltB.
260 volts.
600 TOlts.
1
11.2
16.8
24 JS
2
14.1
19.9
80.9
8
16.1
22.8
85.3
4
17.8
25.1
38.9
6
19.1
26.9
41.9
6
20.3
28.7
44 J»
8
22.4
31.8
49.
10
24.1
84.1
62J
15
27.6
89.
60.4
20
80.4
42.9
66.6
25
82.7
46.2
71.6
90
84.7
49.1
76.1
40
88.2
64.1
88.8
60
41.2
68.2
90.2
80
43.7
61.9
95.9
75
47.1
66.7
103.3
100
61.9
78.4
113.7
126
65.9
79.
122.6
IfiO
60.4
84.
130.
20O
66.4
92.6
143.
960
70.4
99.6
154.
30O
74.8
106.8
164.
400
82.4
116J»
180.
GOO
88.7
125.
194.
flOO
94.3
133.
207.
TOO
99.3
140.
218.
800
103.8
147.
227.
1000
112.
158.
246.
•KW.
Fbr» = 2
^pf^ = 1.4
Kilowatts output of dynamo or intake of motor.
4 6 8 10 12 14 1.6
2.4 3.36 4.2 6 6.8 6.6 73
i
r
374
DYNAMOS AND MOTORS.
Vrtal ValmM for Maximim Allowable Mi
A.nM»t«re Coll.
ibor of It
Formula : /> ^ 240 9 -p Up.
Lap
Winding.
Two-path Windings.
Torus per
Coil.
p = g.
/, = 4.
|> = 6.
p = 8.
1
i.
U
U
240
120
80
60
1
60
30
20
15
S
26
13
9
6.6
3
16
7J5
5
8.75
4
9.6
4.8
3.2
2.4
5
6.6
3.3
2.2
1.66
6
4.9
2.4
1.6
1.22
7
3.75
1.87
1.25
0.03
8
3
1.5
1
0.75
9
2.4
1.2
0.8
0.6
10
1.8
0.9
0.6
0.45
11
1.66
083
0.66
0.42
12
1.42
0.71
0.47
0J5
13
1.22
0.61
0.41
0.3
14
1.06
0J63
0.35
0.26
15
^
PRACTICAL DYNAMO DESIGN.
375
TAJIII.V VI.
mm for Carrytef Cmpm^ity of Ai
2 or 4 Wire* in Parallel Considered a Single Conductor.
Bonnd Wires, Drawn to B. A 8. Oange.
No.
n
M
15
H
13
»
11
I
7
6
2
4
in nar-
alieT
inpar-
aliS.
No.
No.
• •
• •
* •
• •
• •
90
• •
• •
19
■ •
18
• •
17
20
16
19
16
18
14
17
IS
18
13
15
11
14
10
13
9
12
8
11
7
10
6
9
8
7
6
IM X r.p.m. s=
4000 to
eooo.
8000 to
10.000.
Amperes.
2
2i
S
4
6
6
71
9
U
\^
17
21
26
m
40
62
66
80
104
130
160
5
6
74
I
33
40
60
80
100
132
160
200
Rectangular Conductors.
/>• X r.p.m. =r
10,000 to
16,000 to
12/100.
17,000.
•
o
o
«
.a
«
«
s
s
O"
c
a
«
i
1
S
s
1
i
9
i
^*
i
«M
«4
o
o
►»
«»
^
"S
A
A
•d
•o
*»
•*•
a
p
O
o
20,000 to
22,000.
•8
i
I
i
a
c
I
376
DYNAMOS AND MOTORS.
From ** The Dynamo," by Uawkliu A Wallis.
V»1«M Of k,.
a
J=«.
5: =10.
2=12.
}=^
J-".
0»
100
W>
909
B09
1.96
1.86
1.76
1.66
IM
1JS2
2.18
2.06
1.96
1.84
1.75
1.606
2.38
2.23
2.10
1.98
1.89
2.66
2.38
2.26
2.12
2.00
1.90
2.7
2.6S
2jn
2JM
2.12
2i»
Poles =
4
6
8
10
12
14
16
18
20
km =
0.8
0JS6
0.42
0.36
0.3
0.9RA
0.226
0.2
0.18
ai6
From " The Dyxuuno/' by HawkinB ft WaUis.
Wd— Wp_
a -
1
0.74
1J(
\J0
2
1.2
2JS
1.88
3
1.64
9Z
1.68
4
1-8
Avenic« Magvetlc Iieakac« Go«iiel«ati.
KUovaUe =
10
26
40
60
75
100
200
300
600
1000
" =
1.36
1.3
1.27
1.26
1.23
1.2
1.18
1.16
1.13
1.12
PRACTICAL DYNAMO DE8ION.
377
ValvM
•f k^
f
'^•-i.ie
1.17
1.18
1.19
1.20
1.22
1.24
T
MA
0.^
3.10
3.16
8.21
3.26
3.32
3.43
iJA
0.75
3^
3.34
3.4D
3.45
3.51
3.62
3.73
dflO
3.47
3JS8
3.59
8.64
3.70
3.82
3.93
ftiS
3.06
3.72
8.78
3.84
3.88
4j01
4.13
aso
ZM
3.90
8J6
4.02
4.09
4.21
4.38
QJ96
4.03
4.09
4.15
4.21
4.28
4.40
4JSS
1J»
4.21
4.38
4.34
4.40
4.47
4.60
4.72
IJB
4.40
4.46
4.63
4.60
4.66
4.79
4.92
U8
4.58
4.65
4.72
4.78
4.86
4.96
5.12
U5
4.77
4.84
4.91
4i»7
5.04
5.18
5.32
UO
4.96
5.02
5.09
5.16
5.23
6.87
5.52
136
5.14
5.21
5.28
5.35
5.43
5JS7
5.71
1^
6^
5.40
5.47
5JS4
5.62
5.76
5.91
L3S
5JS1
5iS6
5.66
5.73
5.81
5.96
6.11
140
5.69
6.77
5.86
5.92
6.00
6.16
6.31
\A6
6.88
6.96
6.04
6.11
6.19
6.36
6.51
liO
eM
6.14
6.22
6.30
6.88
6.64
6.70
tSB
6.36
6.33
6.41
6.48
6JS7
6.74
6.90
lA
6.43
6.52
6.60
6.68
6.77
6.98
7.10
\M
6^
6.70
6.77
6.87
6w96
7.18
7J»
UD
6^
6J9
6.96.
7.06
7.16
7.32
7.40
US
6J0
7joe
7.17
7.25
7.34
7.62
7.69
liO
7.18
7.26
7.36
7.44
7J»
7.71
7.89
i IJS
7.36
7w46
7i»4
7.63
7.72
7.91
8.09
! »•»
7JS5
7.64
7.73
7.82
7.92
8.10
8.29
i 2410
7.92
8i>l
8.11
8.20
8.30
8.49
8.68
TABUB
ApproprUte DUtributlon of XjOmoi
•
in Per Cent.
•a
3
*^^
*i*t
1
Annatore Lofges.
2 •
■
dp
gH
o
Si
1
Per
Lom;
M
Copper.
Iron.
1^
30
90
44)
8.0
2A
0.5
10
40
90JS
3.8
2.8
3.4
0.5
9JS
60
91
3.6
2.7
2.8
0.4
9
75
91Ji
8.4
2JS
2.2
0.4
8.5
UO
92
8.2
2.4
2j0
0.4
8
200
93
2.7
2.15
1.8
0.35
7
300
98.5
2JS
2.0
1.66
0.35
6Ji
600
94
2.3
1.8 •
IM
0.36
6
TSO
94.6
2U»
1.7
1£
0.3
5.5
1000
96
1.8
IJ^
1.4
0.3
5
378 TESTS OF DYNAMOS AND MOTORS.
TSftTS OF DYlTAHOft AITO HOTOBA.
All reliable manufacturers of electrical maclilnery and apparatus l.
provided with the necessary facilities for testing the ef&ciency and
properties of their output, and where the purchMor desires to oonfixm
tests and guaranties or the maJcer. he should endeavor to have nearly.
In some cases all such tests carried out in his presence at the factory, uz
he may be equipped with sufficient facilities to enable him to carry out '.
tests in his own shops after the apparatus is in place.
Some tests, such as full load and overload, temperature, and insuli
(except dielectric) tests are best made after the macninery has been inst
and is in full running order.
Owing to the ease and accuracy with which electrical measurement*
be made, it is always more convenient to make use of electrical drii
power for dynamos, and electrical load for the dynamo output, and in
case of motors, a direct-current dynamo with electrical load makes the ~
load for belting the motor to.
No really accurate tests of dynamo efficiencies can be made with iratap^
wheels, and only slightly better are those made by steam-engines, owlM
to unreliability of friction cards for the engine itself and the change of £rl»>{
tion with load. |
Where it is necessary to use a steam-engine for dynamo testing, mil Mss
tion and low load cards should be taken with the steam throttled so low m\
to cut off at more than half stroke, and to run the eng;ine at the same speolj
as when under load.
The tests of the engine as separated from the dynamo are as follows :—
a. Friction of engine alone.
6. Friction of engine and any belts and countershaft between it and ths
dynamo under test.
Consult works on indicators and steam-ensines for instructions for detep>
mininff power of engines under various conditions.
The important practical tests for acceptance by the purchaser, or todete^
mine the full value of all the properties of dynamos and motors, are to lesn
the value of the following items : —
Rise of temperature under full load.
lExiulation resistance.
Dielectric strength of insulation.
Regulation.
0\'erload capacity.
Efficiency, core loss.
Bearing friction, windage and brush fHction.
I*R loss in field and field rheostat,
/■72 loss in armature and brushes.
Note.— If a separate exciter goes with the dynamo, its losses wUlbe
determined separately as for a dynamo.
Methods of determining each of the above-named items will be described,
and then the combinations of them necessary for any test will be outlinsd.
V«Hip«rfstar«. — The rise of temperature in a dynamo, motor, or
transformer, is one of the most important factors in determining the Hfe of
such piece of apparatus; and tests for its determination should be carried
out according to the highest standards that can be specified, and yet Iw
within reasonable range of economy. The A. I. E. £. standards state the
allowable rise of temperature above surrounding air for most conditions,
but special conditions must be met by special standards. For instance, no
ordinary insulation ought to be subjected to a degree of heat exceediiv
212° F., or 100° C. And yet in the dynamo-roora of our naval ress^ Uie
temperature is said to at times reach 130° F., or evenhlffher, which leaves t
small marein for safety. It is obvious that speciflcauons for dynamos in
such locations should call for a much lower temperature rise in order to be
safe under full load.
For all practical temperature tests it is sufficient to run a ma<diine onder
Its normal full-load conditions until it has developed its highest temperatnrSi
although at times a curve of rise of temperature may be desired at varioof
loads*
TEMPERATURE. 379
i mauJl djaamos, moton, and transformers, up to, say, 60 K.W., will
Hiaximam temperature in five hours run under full load, If the teiiH
«re riae is ncnrmal ; but lareer machines sometimes require from 6 to 18
•lUuNigh ttxis depeoDds qmte as much on the design and oonstruction
apiwratiia as on size, as, for instance, the5,000 h.p. Niagara Falls Oen-
Kaaeli full temperature in five hours. Temperature tests can be
~ by oTerloadijog the apparatus for a time, tnus reaching full heat
akorter petriod.
dynamoB and motors the temperatures of all iron or frame parts, com-
B, and pole^ieees, have to be taken by thermometer laid on the
and eoTerea by vaste. Note that when temperatures are taken
the iiia<diine runmng, care must be taken not to use enough waste to
the maehine*s radiation. Where there are spaces, as air spaces,
[re eorea or in the field laminations, that will permit the Insertion
tkcrmometer. It should be placed there. Temperature of field coils
rtd te t«Jcen by thermometer laid on the surface and covered with waste,
Vf taking tbe reaistance of the coils first at the room temperature and
B while hot immediately after the kecU run. Temperature rise of arma-
windinsB can be taken by surface measurement and by the resistance
od also ; although being nearly always of low resistance, very careful
kj flne flcalTanometer and very gteadf current are reqtdred in order to
aything like accurate results.
fom&nla for determining the rise of temperature from the rise of
is as follows :
^X v*** ^^ Tcalatance; for copper. — The in-
due to increase in temperature is approximately 0.4%
sik degree Cent, above zero, the resistance at zero being taken as the
If then
1} = tamperatiire of copper when oold resistance is measured (Cent.),
' = resiatance at temperature ^,
, = temperature of copper when hot resistance is taken,
: reeiataiice at tMoperature f«,
Snt reducing to zero degrees, we hare
^ ~ 1 H- 0.0042 ty ^'^
' The increase in reaistance from 0 to 1^ degrees isR,'^ R^^ and hence we
^T« £or final temperature,
^=^^^.f 0.0042 (?)
ptIistttitUng (1) JZ, (1 -f 0.00*2 tx) — Rt .,v
I ^^ 0.0042 iti - ^*'
Jt is etftea convenient to correct all cold resistances to a temperature of
>C, in vbieb case we first redaee to zero and then raise to 20^.
~ ~ formula for obtaining the resistance at t degrees Is \
A = (l-f 0.0042 Qi^.
R^ rs 1J004 Ko and in terms of the cold resistance at temperature t.
^""(14-0.0042/} ^'
<3> then becomes, when the cold resistance is at 20^^,
first formula requires but une setting of the slide rule, and the sub-
of the eoastant 238 can usually be done mentally, the advantage of
equation la tids f ona is very great as regards both speed
coefflcieiits most generally used are
0042
Ybriron 004B
Par German sUver .00028 to .00044
380 TESTS OF DYNAMOS AND MOTOB8.
The following parts should be tested by the resiatanee method and tte
surface methotralBO :
Field coUs series, and shunt.
Armatwre eaiU, In 8-phase machines, take resistanoe between all time
rinKS.
llie following parts should be tested by thermometer on the snrfaee : —
Boom^ on side opposite from steam-engine, if direct connected, and always
in two or more parts of the room, within six feet of machine.
JBearingSt each bearing, thermometer held against inner shell, nnleae oU
from the well is found to be of same temperature as the beazing.
Commutatorg and collector rings.
Brvsh-holdera and bruthea^ if thought hotter than the commutator.
Fole-tipi^ leading and following.
Armature teeth, windings, and spider.
Field/rame.
Terminal block$, for leads to switch-board, and those for leads from tih*
brushes.
Series akuntt if in a compound-wound machine.
Shunt field rheostai.
On transformers which are enclosed in a tank filled with oU,temperatcmi
by thermometer should be taken on —
(hUHde ea««, in several places.
OU, on top, and deeper by letting down thermometer.
Winding$t by placiniz thermometer against same, eren if under oil.
LaminaHontt by placing thermometer against same, eren if under oil.
TerminaU.
Boomf as with dynamos and motors.
Also resistanoe measurements of primary and secondary windings, £roiB
which the temperature by resistance can be calculated as shown.
On transformers cooled by air forced through spaces between windings
ind spaces in laminations, temperatures by thermometer ahonld be taken
•n~
Outside /irune*
Air, outgoing from coils.
Aitt outgoing from iron laminations.
Windings.
Terminals.
Boomt in two or more places.
Also resistance measurements, hot and cold, should be taken, from which
rise of temperature by resistance can be calculated.
Finally, the cubic feet of air, and pressure to force same through qmums
(easily measured by " U " tube ot water), should be measured.
When other fluids are used for cooling, such as water passing through
piping submerged in oil, in which also the windings and core are submerged,
or through windings of transformers themselves (made hollow for the pur*
pose), the temperature of incoming and outgoing nuid should be measured,
the quantity used ajnd the pressure necessary to force it through the path
arranj^ed. besides the other points mentionea above.
Careful watch of thermometers is necessary in all eases, as they will rise
for a time and then begin to fall : and the maximum point is what u wanted.
British authorities state a demiite time to read the therm<mietera after
stopping the machine.
Care must also be taken to stop the machine rotating as soon as possible,
so that it will not fan itself cool.
A handy method of constructing a curve showing thexise of temperature
in the stationary parts of a machine at full load is to insert a smau eoil of
fine iron wire in some crevice in the machine in the part of which the tem-
Serature is desired. Connect the coil with a mirror galvanometer and
attery.
The temperature ooeffloient of Iron is high, and the gradual increase in
resistance of the coil will cause the readings on the gammometer to grow
gradually less ; and readings taken at regular intervals of time can be
plotted on oross-eeotion paper to form a curve showing the ehanges in
temperature.
TEMPERATURE. 3S1
Mmemr^m •f tmmnfmrmtmw i««t. — During all heat mna readingi
•honld be taken erery iuteen {IS) minutes of the following itemt:
On direct and alternating current nu>tor8 and generators —
AiDiatiire, Yolts (between the ▼arlous rings where maobine is more than
single-phase, In the ease of alternators, and between bmshesi
* in the case of a D. G. machine).
Amperes (in each line).
Speed,
field. Volts.
On synchronous eonyerters : —
Armature, Tolts (between all rings on A. O. end, and between brushes on
D. C. end).
Amperes, per line A. C. end, also D. C. end.
Speed.
Pleld, Volts.
Amperes.
On transformers, compensators, potential regulators : —
Volts, primary.
Volts, secondary.
Amperes, primary.
Amperes, secondary.
Cycles.
Amount and pressure of oooUng-fluid (If any Is used).
On induction motors : —
Volts, between lines.
Amperes, in line.
Speed.
Cycles.
•rerlofliA —The A. I. E. E. standards contain suggestions for orerload
ettsdty (see page 303).
the writer has uniformly specified a standard overload of 26% for 3 hours,
sad there seems to be no* especial difficulty in getting machines for this
ittadsrd that do not heat dangerously under such conditions.
lMi«l»tl«m tcet« — Insulation resistance In ohms Is of much less Im-
portsnoe than resistance against breakdown of the insulation under a
itratm test, with alternating current of high pressure.
Mske all insulation tests with a Toltage as high, at least, as that at which
the machine is to be worked.
The following diasram shows the connections to be made with S some
external souroe of B.M.P. The formula used is
J^sresistamoe of voltmeter. .._
B = E JiJ. of the external source. nlSm\
c = reading of voltmeter eonneeted as in I | ^
mce in ohms. unarm " >f
x= insulation resistance in ohms. Mna^
According to the A. I. E. E. standards,
the insulatwn resistance must be such that Fio. 1. Connections for volt-
tbe rsted voltage of the machine will not meter test of insulation re-
aend more tlian rnknp of the full-load cur- sistanoe of a dynamo,
rent through the insulation. One megohm
k umally considered sui&cient, if found by such a test. Where one megohm v
iiipecifled as sufficient, the maximum deflection that will produce that
Tslne, and that must not be exceeded in the test, may be found by the f ul-
ioving variation of the above formula :
BXB
Itrttia tost.— llie dielectric strength of insulation should be deter-
mined by a eontinued application of an alternating E.M.F. for at least one
(I) minute. Tlie transformer from which the alternating E.M.F. is taken
ihoQld have a current capacity at least four (4) times the amount of current
382 TESTS OF DYNAMOS AND MOTORS.
BeoMsazy to olmrge the apparatoB mider test aa ft Aondenter. Btrmln
■hoald only be made with the apparatus f uIIt assemhled.
Gonneot on a D.O. machine as in the following diagram.
Strain tests should be made with a sine
-., B wave of B.M.F., or with an E.M.F. haTii^
nmiaBi\ "K"- ^® ^™o striking distanee between noedle
P""™^ m points in air.
L^O/ ^i A^ , .nr .. See article 219 A. I.B.E. standards for
■— r^rtT. i3« ii»! A. proper voltages.
^^ ri li*J © lKr«liSo«.-The test for rs«»l*-
/ \^|>* n o T J *ion in a dynamo consists in detemmiiiw
^gnAMc — ' tts change in voltage under differaS
^^ loads, or output of current, the speed be-
Fio. 2. Connections for strain ingmaintained constant,
test of dynamo or motor or The test for r^^ulation in a motor
transformer insulation. consists in determining its change of
speedt under diiferent applied loads,
when the voltage is kept constant.
AtaMdar^U.— For full details of standards of reffulation of different
machines, see report of the Committee on Standardisation of the A. I. S. E.
at Uie beginning of this chapter.
lieff«latloM Testa, Dyaaaios, ftkoat mr CaaspooBA, asiid
The dynamo must be nm for a suflDksle&t length of time at a heavy load to
raise its temperature to its highest limit : the field rheostat is then adjvistsd,
starting with voltage a little low, and bringing up to proper value to obtain
the standard voltage at the machine terminals, and since a constant temper-
ature condition ha» been reached, must not again be adjusted during the
test. Adjust the brushes, in the case of a D. C. machine, for falMoad oon-
ditions, and they should not receive other adjustment during the test. Tlds
is a severe condition, and not all machines will stand it ; but all good dy-
namos, with carbon brushes, will stand the test very well, provided the
brushes are adjusted at Just the non-sparking point at no load.
Load is now decreased by regular steps, and when the current has settled
the following readings are taken : —
Speed of dynamo (adjusted at proper amount).
Current in output (a non-inductive load should be used).
If alternator, current in each line if more than singlei>hastt.
Yults at macnine terminals.
Amp«:es, field.
Volts, field.
' Note sparking at the brushes (they should not spark any with oarbon
brushes).
Readings should be taken for at least ten intervals, from full load to open
circuit (no load) ; and load should then be put on gradually and by the same
steps as it was brought down ; and the same records should be made back
to full-load point, and beyond to 25% overload.
If the readings are to be plotted in curves, as they always should be, 11
will make little dilference if the intervals or steps are not all alike ; and
should the steps be overreached in adjusting the load, the load must not, in
anv circumstances, be backed up or readjusted back to get regular Inter-
vals or a stated value, as the conditions of magnetisation change, and throw
the test all out. In case the current is broken, or the test has to be slowed
down in speed or stopped, it must be commenced all over again. Finally,
when the curves are plotted, draw, in the case of a eompound-wonnd ma-
chine, a straight line joining the no-lemd voltage and the full-load voltase ;
and the ratio of the point of maximura departure of the voltage from tnil
line to the voltage indicated by the line at the point will be the reffttiation
of the machine.
The readings as obtained give what is called a field compounding enrve.
In the case of a shunt or separately excited machine, the procedure for the
test is the same : but when the curve Is plotted, the regulation is figured ss
equal to the difference between the no-load voltage and full-load voltage,
divided by the full-load voltage. The curve is called a oharaeteristio la
this case.
DYNAMO EmCISNCT. 383
Par ftltanwion thftt are too large to apply aotiial load as sugfested aboTo,
■other " no>load '* method eommonlj oned with sattsfaotory reenlts upon
jllernatori designed upon the usual linee is to short-oirenit the alternator ar-
■atore upon itself and determine the amperes in the field required to produce
varmal eurrent in the armature so short-ciroulted^e speed of the machine
Mni normal at the time ; call this eurrent F, Take anothei' reading of
%b field eurrent required to produce normal Toltage at the machine ter-
■faials, with the armature on open circuit and the speed normal ; call this
nrisnt C. Then the current required in the field winding for full non-
MnetiTeload will be /= Vin+ C*.
Having calculated the ralue of this current, pass it through the field
■ladings of the alternator with the armature on open circuit and running
tt normal speed, and read the Tolts F. Let E = normal Toltage, then the
Hgnlstien ^ iy ^*
The current l^is called the " Synchronous impedance *' field current, being
n named by Mr. G. P. Steinmets, who proposed and has used the above-
ieKribed method.
When regulation is desired for a power factor other than unity the field
wrents >^nd C must be combined at the proper angle corresponding to
the power factor. For instance, for a power factor ox 0 (i.e., Wfi lag) the
leld currents would be directly added. This method is used extensiTsly
nd gfres results agreeing very well with those of actual tests.
Kttf«lss««m Scats, Kot«rs, Slhwit, ComfcwmA,
iBdvctlom.
After drhrfnff the motor under heavy load for a length of time sufllcient
to develop its full heat, fuil>rated load should be applied, the field rheostat,
tt toy is used, and brushes adjusted for the standard conditions ; then the
Mikmld be gradually removed by regular steps, and the following read-
lap be made at each such stop : —
Amperes, input.
Volts at machine terminals (kept constant).
Watts, if induction motor.
Speed of armature.
Koto sparking at brushes.
Amperes, field (in D. C. machines).
At least ten steps of load shoold be taken from full-rated load to no load.
The ratio of the maximum drop in speed between no>load and full-load,
vlkieh vill be at fuU-load, to the H>e«l »t fnU-load, is the rtgukUkm of the
■olor.
XiktCBcx Teste. I^ymamoa.
As term <|leieii«|f has two meanings as applied to dynamos ; yiz.^ electrical
J^d ettmmereuU. The eUctriceU efflciency of a dynamo is the ratio of eleo-
tneal energy delivered to the line at the dynamo terminals to the total electri-
nlenergv produced in the machine. The commercial efficiency of a dynamo
■ttwraflo of the energy deHrered at the torminals of the machnie to the total
■MrS7 fuppUed at the pulley. Otherwise the electrical efilcienoy takes into
•eeonnt only electrical losses, while the commercial efAciency includes all
nvM, electrical, magnetic, and frleUonal.
CareXcaa Teat, aadi T^ut for X'rlctioa and ITlBdisffe.
T^Mse losses are treated together for the reason that all are obtained at
ueiame time, and the first can only be determined after separating out the
«cbeii.
A eore>loss test is ordinarily run only on new types of dynamos and
■totoTt, but Is handy to know of any machine, and if time and the facilities
ve available, should be run on acceptance tests by the consulting engineer.
U eonsists in running the armature at open circuit in an excited field, driv-
ing it by belt from a motor the input to which, after making proper deduc-
"<>Qi, is the measure of the power necessary to turn the iron core in a lield
01 the same strength as that in which it wiu work when in actual use.
i
i
384 TESTS OF DTKAMOS AND MOTORS.
Conneot at In tb» f oUowlng diagram, la wliSoh A is dio drnamo or
under teat, and B la the
motor driving the
tore of A hy meana of
the belt. The Held of A
muat, of heceMlty, be
aeparately excitea, aa
Its own armature olronit
moat be open bo that
there may be no current -iKS^SS-
generated in its oonduo- ■*•*** ^
wTB. Fio. 3. Conneotiona for a test of oore Visa.
The motor field is sep-
arately excited and kept constant, so that its losses and the oore loea of thaj
motor itself, being constant for all conditions of the teat, may be «*f^FM^tHttfl
in the calculations. The motor B should be thorou^ly heated; and besi^!
ings should be run long enough to have reached a consumt frietlon eoniii*
tlon before starting this test, so that as little change as possible will tafct
place in the different " constant" Taluea. It is neeessary to Icnow aoea*
rately the resistance of the armature, B, In order to determine its I^B loss
at different loads, and to use copper brushes to practically eliminate As
/*/{ of brushes.
It is well to make a test run with the belt on in order to learn at whit
speed it is neeessary to run the motor in order to drive the armature A at Hi
proper and standard speed.
nf ettoB, core l«aa, aiad wtstdagr* of asotor. — The speed havtac
been determined, the belt is removed, and the motor field kept at ita final
adjustment, and enough Toltage is supplied to the motor armature to diiTS
it free at the standard speed. The watts input to the armature is then the
measure of the loss (I*it) in the motor armature plus the friction of ita bear-
ings, plus its windage, plus core loss, or the total loss in the motor at no
load. This is called the " runnins light '* reading.
I*rictloa asid wiBda|fr« of oynAflso.— After learning the lossss
in the driving motor, the belt is put on and the dynamo is ariTon at Its
standard tpeSa without excitation, and In order to oe sure of this a volt-
meter may be connected across the armature terminals ; If the allghtest
indication of pressure Is found, the dynamo field can be reversely excited,
to be demagnetized, by touching its terminals momentarily to a source of
E.M.F. Take a number of reaolnflpB of the input to the motor in order to
obtiUn a good mean, and the friction and windage of dynamo la then the
input to the motor, less the " running light " reading previously ohfalned,
the I*B of motor armature having been tiken out in eaok oaaa.
Let P = watts input to motor,
P. = 7> Jt loss in motor armature when driving dynamo,
/=** running light " reading of motor,
/, = friction and windage of dynamo atmature,
P. = />/{ loss of motor armature when ** running lisdht,"
then /J = p-(Pj4./-p,).
Brauili friotioa.— The friction of brushes is ordinarily a smalt portion
of the losses ; but when it is desirable that it should be separated from other
losses, it can be done at the same time and in the same manner as the test
for bearing friction. The brushes can be lifted free from the commutator
or collector rings when the readings of input to the driving motor for bearing
friction are taken ; dropping the orusbes again onto the commutator and
taking other readings, tne difference between these last readings and those
taken with brushes oil will be the value of brush friction. Note, that alIow>
ance must be made as before for Increase of T*R loss in the motor armature.
Xoat for eort) loaa. — Having determined the friction and other lossss
that are to be deducted from the total loss, a current as heavy as will ever
be used is put on the dynamo field, the motor is supplied with current
enough to drive the dvnamo at its standard speed, and the reading of watts
and current input to the motor armature is taken.
The dynamo field current is now gradually decreased in approximately
regular steps, readings of the input to the motor being taken at each such
step until zero exciting current is reached, when the exciting current is
reversed and the current increased in like steps until tlie hli^est current
DYNAMO EFFICIENCY.
385
_ ta again readied. This may nov be again decreased by Interrals
;toxero^ rerened and increased back to the starting-point, which will
complete a cycle of magnetization ; ordinarily this refinement Is not,
MTi neceBsaxjT*
test moat always be carried throagh without stop ; and although It is
• to make the step changes in flem excitation alike, if the excitation
pad In exoeaa of the regular step it must not be changed back for the
of making the interral regular, as it will change the conditions of
'oal Held. When the readmos are plotted on a curve, regularity in
of magnetization is not entirely necessarr.
fc4k>wing ruling makes a convenient methoa of tabulation : —
1 ImiAMO.
MoToa.
h
amperes
field
Speed
amperes
field
amperes
armature
i
TOltS
in
armature
e
L
Constant.
Constant.
OOMPUTATIOHB.
Itttoia
Running
PR
PB
Core loss
Mure,
light
Inarm,
inarm,
belt oft
CtOB
reading
belt on
P..-(Pi+/-Pi)
fm=^it
f
Px
^t
iw curve with exciting-current values on the horizontal scale, and
) loss on the Tertical, and the usual core-loss curve is obtained.
mm mft Core
iMto K/s««rMls mmA Kddy
^ due to hysteresis and friction vary directly with the speed \ lossed
>eddy currents vary as the square of the speed.
jmx and voltage must now be applied to the dynamo armature to
I ft M a motor at proper speed, with the current in the separately
•-ed Iftld kept constant at proper value. Drive the motor (dynamo) at
r tPodUferent speeds, one or which may be K times the other ; let
P = total loss in watts,
/. = loss in friction,
ir = loss by hysteresis,
D = loss by eddy currents, or
/» = A -j- ^4- 2) at the first speed,
p,-=.Kfy\- KH-\- IPDsX second speed,
i
{
tr=2,then
"~2(2— D 2
sad HoQsman separately devised the above method of separating
M, but stated them somewhat dUferently.
ttbe field separately excited at a constant value, different values of
''are supplied to the armature at dilferent voltages to drive it as a
. Tke results are plotted in a curve which is a straight line, rising as
^^<te sre iaereaaed.
{
386
TESTS OF DTKAICOS AND MOTOBS.
>
\
)
The following diacEram shows how the loeses are plotted in curreB.
test as a separately exdted motor is run at a number of different values
voltage ana current in the armature, and the results are plotted in a
as shown in the following diagram. The line a, 6, is plotted from the
of the current and volt readingi.
The line a, e. is then drawn parallel to the base, and represente the sum <
all the other losses, as shown by previous tests, and they may be fi
separated and laid off on the chart.
Foueault currents are represented in value by the trian^e a, c, b.
If another run be made with a different value of ^excitation, a curve, at, -
or one below the original a, b, will be gotten, according to whether the tot
losses have been increased or decreased.
If the higher values of current tend to demagnetise, by reason of the
currents in the armature, the curve a, 6, will curve upward somewhat at
upper end.
it is thus seen how to measure core-loss, and friction and windage cf
dynamo ■ knowing this and the resistance of the various parts, the emcienc
is quickly calculated, thus
Let P — core-loos + friction (obtained as shown).
V -• voltage of armature,
■- current of dynamo armature,
— current of dynamo field,
" resistance of armature and brushes,
B resistance of field.
/
■oatH FmoTioii
■nCTHMMlDWiHOMQS
9
Then, considering the above as ihe only loasee (l.e., negleetlag rl
etc.), jpr
Efficiency - ——.^—j^^-^p .
This Is a satisfactory method of getting the effioienoy, bat does not 1
• ^ In 'Hoad loMes" If
should exist.
The simplest meth<
of determining the
ciency of a direct-eoi
machine is to nm it'
as a motor, without
or belting or geaiinj
its proper field streL
and its proper speed
measare the mpiit
the armature, Fran
value subtract the PI
loss in the armatare
the remainder Is the <
and friction loss. Knoi
ing this and the
tance of the remali
circuits, all the k
are known, and h«u
the ef&ciency can be cal-
culated. This method is
an accurate one and Is
easy to carry ont.
Amother toe* for
•flcl«Mcy . — 11 the dy-
namo under test is not
of too large cMacity, and
a load for its full output is available, either in the form of a uunp bank,
water rheostat, or other adjustable resistance, then one form of test is to
belt it to a motor.
By separately exciting the motor fields, and running the motor free with
belt off, its friction can oe determined, and with the resistance of the srma-
ture known, the input to the motor in watts, less the friction and thei^Je
loss in its armature at the given load, is a direct measure of the power ^h
Slied at the pulley of the dynamo. The output in watts, measured at the
ynamoB terminals, then measures the efficiency of the machine.
VQCn m ABiumsr
»^
Fio. 4. Diagram showing separation of losses
in dynamos.
DTNAMO KFFICnurCT.
387
Ii«* P = watts Input to motor.
Pi = losaes in motor, friction, PR^ and oore-loBf ,
Pi = watts output at dynamo terminals.
% of e£ELciency = 100 X p^p^ = commercial efficiency.
Knowing the current flowing in the armature and In the flcldB. and also
1 »*'T"^*\® resistonce of the same, the PR loBses In each may be calcu-
lated, which, added to the output at the dynamo terminals, shows the total
deetrieal energy generated in the
machine.
lla-tbe^i21o68 in the armature, ^ - i ne-o
/ -the P 12 loss in the fields. ^ ' ^^^
Ths electrical efficiency in ner-
cestage wUl be * *«
Tke adjoining diagram showa the
eoaaaetlons for this form of test.
It mat be obrious that a steam-
€ngIse,or other motiye power that
can be accurately measured, may be
JMod in place of the electric motor :
bet measurements of mechanical
power are so much more liable to
vrar that they should be avoided
vbere possible.
The only obiectlon to this method
ttttst the friction of the driving-motor varies with the load, and the loas
u ths belt is not considered.
OENERATOR
UNDER TEST
Fio. 6. Oonnections for efficiency
test of a generator, driven by an
electric motor.
Kftpi^s TMt wltk Tw« Slflsaar JMract-Cvn^at DjaaaaiM.
Where two similar dynamos are to be tested, and especially where their
e^»clty is so great as to make It difficult to supply load for them, it is com-
"jjp to test them by a sort of opposition method ; that is, their shafts are
•{•■«r «>i>pled or belted together, the armature leads are connected In series,
we leki of one is weakened enough to make a motor of It ; this motor drives
8f ^•iS'' ">»«*>*'>« a» * generator, and Its current is delivered to the motor
I u ^w^nco in currents between the two machines, and for exciting the
i«NB of each. Is supplied by a separate generator.
The following diagram shows the method of connecting two similar
SWITCH
{
Fio. 6. Connections for Kapp*B method of efficIenoT
test of two similar dynamos.
388
TB8TS OF DYNAMOS AND HOTOBS.
dynamo* for Kapp's test. D is the dynamo ; M the machine vlth fteld
weakened by the reslstanoe B, that acts as a motor, and O Is the goneracor
that supplies the energy necessary to make np the losses, excitation and
differences.
Start the combination and get them to standard voltagOf as shown by the
Toltmeter : then take a reading of the current with the switch on 6, and
another with the switch on a. Xet the first reading be m, and the seoond <
and let x be the efficiency of either machine, then
Per cent efficiency of the combination = 100 x -ft <uid
=V(ioox^).
In using this formula the efficiency of the dynamo at its load is aasumsd
the same as the motor at its simultaneous load, which is usually true aboie
the I load point. The loss in motor-field rheostat should also be allowed for.
Another similar method, called **pumpinq back," is to connect the shafts
of the two machines as before, by clutch or belt ; arrange the eUotriesl
oonneottcms and instruments as in the following diagram :
Fto. 7. ' Efficiency test of two similar dynamos.
D is the dynamo under test ; M is the similar machine used as a motor;
and G is the generator for supplying current for the losses and differenest
between M and D. The speed of the combination, as well as the load on D,
can be adjusted hy raxyiua the field of M.
The motor, M, drives D bv means of the shaft or belt connection. M geto
its current f dr power from two sources, yiz. , G and D. In order to detennlDS
the amount of mechanical power developed by M, and also to be able to
separate the magnetic and frictional losses in the two machines, a oore4M>
test should have been made on the machine M at the same speed, eurreol^
and E.M.F. as it is to have In the efficiency test. The loss in the cable oon-
nections between M and D must also be taken into account, and is eaual to
the difference in Tolts between roltmeters c and 6, X the current nowinl
in ammeter n.
Let
r= E.M.F. of D, shown on c,
F, r= E.M.F. of M by rm. 6,
K/y = E.M.F. of G by tbci. a,
/= amperes current from D by am. n,
I, = amperes current from G by am. I,
Iff = amperes current In M = / + A,
€ = drop in connections between D and M = F— 9^
L = loss in connections between D and M r= e X /|
r = D*8 internal resistance,
Tx = H*s internal resistance,
w = core loss -4- armature loss -f- field loss + friction of M is
watts + L (loss in connections).
'm
SLECTRICAL METHOD OF SUPPLYING LOSSES. 389
Tb
fr= the Qflefnl output of D = F x A
Wf =: tnem supplied by O = V„ X //,
W-\-WiZs. totafenergy sapplled to M,
ir+ Wf — «r = energy required to drive D,
nr
% commercial effloienoy of D =
JV = electrical loss In D,
% electrical efficiency rr
w
xioo.
>r + /«r
XIOO.
Tbe other way of calculating the efflctenov with this arrangement is to
yutMaox^ the output = Wy from O, with full load on D. Wx then is the
kMsas of boUi machines under load ; and knowing the /*A loss In the arma-
tare and field of each, the efficiency is quickly and accurately calculated.
Thk method ia best, as no core loss is required, and includes the " load
Hetk^kl of AopplytniT tlftfi
Sfct
Mod^leaHon qf " Kapp Method,'* by Prcf. Wm. L. Pvffertfrofn noiti
privuLtely printeafor the itudents of the Maseachtuett* Institute
of Technology,
0p«clflcatiOB.
Two similar shunt dynamos under full load, one as a motor driving the
other as a loaded dynamo through a mechanical coupling. Mains at same
voltage a» dynamos, and only large enough to supply the full-load losses of
bomaynamos.
line up the two dynamos carefully, and mechanically connect them by
a good form of mechanical coupling, strong enough to transmit the full load
to the dynamo.
Connect the field magnet windings of each machine to the supply mains,
natttoc a suitable fiela rheostat In each. If desirable for any reason, the
field of the dynamo may be left connected as designed ; but the field of the
motor, which does not in any way enter as a quantity to be measured during
the test, should be c<mnected to the supply mains.
Fio. 8. Diagram of Connections for Professor Puffer's Modifir
cation of Kapp's Dynamo Test.
Mtetliod of AtsMrttng*.
dose the field oirouit of the motor, and by the motor starting rheostat
gradually bring the motor up to full 8i)eed. The dynamo armature will be
alio at proper speed and on open circuit. Now close the dynamo field and
at^ust the field rheostat until the dynanio is at about normal voltage.
▲4vt t^o speed ronshly at first by the use of the field rheostat of the
motor, remembering that an added resistance will cause the speed to rise^
Next see that the voltage of the dynamo is equal to that of the motor, or,
ia othn* wordSf that there is no difference of potential between opposite
sides of the main switch on the dynamo. Close this switch and there may,
or may not, bo • amaU eurrent in the dynamo armature. Now carefully
390 TESTS OP DYNAMOS AND MOTORS.
increase the armature voltage of the dynamo, watching the ammeter^ and
weaken that of the motor ; a current will flow from the dynamo to the
motor, and the motor will transmit power mechanically to the dynamo.
The current which was first taken from the supply wires to run the motor
and dynamo armatures will increase somewhat. By a careful adjustment
of the two rheostats and the lead on each machine, the conditions ot f uC
load of the dynamo may be produced. The motor Is overloaded and Its arm-
ature will carrr the sum of the dynamo and supplv currents. Great care
must be taken in adjusting the brushes of the machLaes, because of great
changes in the armature reactions which take place as the bruahee are
moved. It is well to remember that a backward lead to the motor brushes
will increase the speed, as the armature reactions will considerably weaken
the effective field strength.
Gautloita.
The increase of speed will raise the dynamo voltage, and eause the cur-
rent flowing in the armatures to greatly increase. A forward movement of
the motor brushes will reduce both speed and current. A forward move-
ment of the dynamo brushes will increase the armature reaction, and cat
down the current through the armatures, while a backward movement will
cause it greatly to increase. Very sreat care must be taken in adjusting
the brush lead, as a movement oi the brushes of either machine, which
would be of little importance luually, will produce sometimes a change in
current value equal to the full-load current. It is quite possible but poor
practice to produce the load adjustment by use of the brushes alone.
It is best to have ammeters of proper sise in all circuits, but those actually
required are in tlxe dynamo leads and in the supply mains. A single volt-
meter is all that is required.
The field magnet circuits ought to be connected as shown, and the am-
meters placed so that the energy in the fields does not come into the test of
the losses in the armatures. The magnet of the machine under teat, a
dynamo in this case, should be under the proper electrical conditions for
the load, yet not in the armature test, because the object of the test can bert
be made the determination of the stray power loss under the conditions of
full load ; then having found this, assume the exact values of E, I, and
speed, and so build up the data for the required efficiency under a desired
set of oonditions which might not have been exactly produced during the
test.
Immediately after the run, all hot resistances should be measured ss
rapidly and carefully as possible, to avoid smj error due to a change in
temperature.
The energy given to the two armatures less the I*R in each armaturSt
will be the sum of all the armature losses of the two d3rnamoe under the
conditions of the test, so that we measure directly the armature lo^tes of
the dynamos while fully loaded.
It is evident that the two armatures are not under exactly the same 000-
ditions, except as to speed, for the dynamo armature will have an intensity
of magnetic field that will give an armature voltage of Vf -f* ^A^A*^^^^
the motor will be weaker as F^ is the same for both armatures, and tbe
motor armature voltage will be Vf — ^A^A» ^^^ the iron core losses wiUba
made much greater in the dynamo than in the motor. The motor armature
must carry a current equal to the sum of the dynamo and supply currents,
and will get much hotter : its reaction will also be greater, and there will be
a tendency for greater sparking at the brushes.
The total stray power thus obtained may be divided between the two
armatures equally, but preferably in proportion to the armature voltages,
unless the true law for the armatures is known. All resistances of wires, etc,
must be noted and corrections applied, unless entirely negligible.
Two 15-H.P. dynamos were tested by the class of '93, usijig this method.
One of the full-load tests is here given as a sample of calculation. Ths
exact rating of the dynamos Is not Known, but is nearly 46 amperes at 230
volts, with the dynamo at a speed of 1600 r.p.m.
KUSCTBICAL METHOD OF SUPPLYING LOSSES. 391
The averages of tlie obserred readings taken during the test, and after a
mn of about fire hours to become heatod, was as below.
Sxaaaple of Calc«latloa,
(Connections as shown in Fig. 8.)
Volts at supply point 220.3
Amperes ox 16.71
Output of dTnamo, amperes 46.80
I>Tnanio field current 1.M6
Speed 16M.
To Meature Armature HeHttance.
Motor F= 1.962 /= 10.18
Dynamo r= 2.406 7=10.06
The motCM' field is out of the test while the dynamo field is in the test.
Calculation.
Watts supplied 220.3 x 15.71 = 3461.
Dynamo armature J2. =5 Motor armature Ji» =
_. 2.406 AM<OT n 1.962 -A.n
*-=io:08=-^ ^=10l8=-*«^«
PmtRmd nmm lUm
U = 45.80 + 1.M = 47.74 7« = 45.80 + 15.71 =. 61.61
47.74* X .2387 = 56i=PmRmd 61.613 X .1918 = 725.4 = 7*. /2m»
Dynamo Field = 1.946 X 220.3 = 428.4
Watts supplied = 3461
Dynamo field = 428.4
PR M =i 726.4
PB D z=i S54.0
Total heat lost = 16U7.8 1608
Total stray power = 1763 watts, for both machines.
47.74 X .2387 = 11.4 + 220.3 61.61 X .1918 = 11.8 + 2203
= 281.7 =r VmA. = 206JS = r«».
Diride the total stray power between the two armatures as their arma-
ture Toltages.
231.7
Stray power of dynamo, 231.7 +208.5 ^ *^® ~ ^^'
Stray power of motor r= 1763 — 028.0 = 835.0.
The quantity 928.0 is the object of our test, i.e., the stray power when
is nearly as may be under actual running conditions.
Calcwlatton of Xfiidond^.
As run.
Output of dynamo = 220.3 X 46.80 = 10090 Watts output
' 664 HRmd
10090 428 Field
644 928 Stray power
428 11990 Watts input to the dynamo.
11062 = Work done by current.
392
TESTS OF DYNAMOS AND MOTORS.
Effloienoj of GonTenlon:
11002 X 100
11990
= 92.2 per cent.
Gommerolal eiBoienoy;
10090 X 100
119.90
r= 84.1 per cent.
=: 16.1 H.P.
Power required to run dynamo:
11990
746
In this test, carbon bruahes were used, and the lead adjuBtod afe carefvUt
AS possible, if the exact rating of this dynamo had been 46 amperes and S20
▼olts at a speed of 1000. and we wished to find the efllolencies corresponding,
we should proceed In this way.
The test was made under conditions as nearly as possible to the railng,
and the stray power as found will not be perceptibly different from what It
would be under the exact conditions.
When the load has been as carefully adjusted as in this test, It Is seldom
worth while to make these corrections, as they are smaller than ehaoffes pro-
duced by accidental changes of oiling, temperature, brush pressure, eCe,,
of two separate tests.
itac«a of tta« Metfewd.
Small amount of energy used in making the test, namely, only the losses.
No wire or water rheostat required. Test made under full load, and yet
the losses are directly measured. AH quantities are expressed In terms de-
pending on the same standards, and therefore the efflcienovwill be but little
affected by any error In the standards. No mechanical power messure-
ments are mikie, and all measurements are electrical.
Bequires two similar machines. Armature reactions are not alike In both
machines. Leads are not alike. The iron losses are not the same. No belt
pull on bearings. Must line up machines and use a good form of mechanical
coupling. Sometimes difficult to set the brushes on the motor. The motor
armature is much OTorloaded.
RH.
RK.
scpar9<te exciter
for fields
of motors
FlO. 9. Diagram of Connections for Test of Street
Motors, Prof. Puffer.
Gar
ELECTRICAL METHOD OF SUPPLYING LOSSES. 393
(LflA
FIKLO
Fio. la Diagram of Connections of ModUoation of the
Preylona Diagram, by Prof. Puffer.
lUs melhod Is of advantage In the test of railway seriee motors, If slightly
modified bj the separate ezoitation of the motor fields. If the series field
vliidlna be not separately excited there will be a great deal of nnneces-
nry difflcolty from great changes of speed as the load is raried. HoweTer.
one field may be kept in circuit on the machine used as a motor, as ihe test
esn then be made with the motor under its exact conditions. There will be
a rery great change of speed during adjustment of load, but there will be no
dssfer of injurinflr anything, as the separate excitation of the dvnamo field
is an aid to steaolness. lutilway motors, as generally made, iRill not stand
tfaslrfnll rated load continuously, and tne motor is likely to get too hot if
not watched ; the machine Ufted as a dynamo will run cold, as it will not
have a large current in it. The friction of brushes is very large In these
BMitors, and in general there is a want of accuracy In the diyision of the
total stray power between the two armatures. It can only be very approxi-
mately done by the aid of curves showing the relation between speed and
stray power, and armature voltage and stray power.
IftyMmaem's K«et of two Siaillmr I^lroct-CTmrromt Pymmmioe.
In the original Hopkinson method, the two dynamos to be tested were
placed on a common foundation with their shafts in line, and coupled to-
gether. The combination was then driven by a belt from an engine, or other
source of power, to a pnlley on the dynamo shafts. The leads of both ma-
chines were then Joined in series, and the fields adjusted so that one acted
as a motor driven by current ftom the other. The ot^ide power in that
esse sni^lied, and was a measure of the total loesea in tne combination, the
efficiency of either machine being taken as the square root of the efficiency
of the combination.
Many modifications of this test have been used, especially in the substitu-
tion of some method of electrically driving the combination, as the driving-
power is so much easier measured if electncal.
This test is somewhat like that last given, but the two machines are con-
nected in ssHes through the source of supply for the dWerence in power,
soeh as a storage battery or generator. The following cuagram shows the
eonneetions for the Hopkinson test, with a generator tor supplying the dif-
ference in power.
In this test the output of G plus enezgy taken by M| (motor driving the
system), gives losses of motor and dynamo (the losses of M, being taken
out), lliese losses being known, the efficiency can be calculated.
If the two machines D and M are alike, O supplies the i^^ losses of arma^
tores, and M the friction, core losses, and /> Rot fields.
Another method useful where load and current are both available, is to
drive one of two similar dynamos at a motor, and belt the second dynamo
to it. Put the proper load on the dynamo, and the efficiency of the com-
Unation is the ratio of the watts taken out of the dynamo to the watts
sumllsd to the motor. The efficiency of either machine, neglecting small
dineienees, is then the square root of the efficiency of both.
r
394
TESTS OP DYNAMOS AND MOTORS.
A.M.I
Fia. 11.
Diagram of connections for Hopklnson'8 test of
two similar dynamos.
If
watts put into the motor,
watts taken from the dynamo,
per cent efficiency of the combination,
efficiency of either machine,
Px XlOO
The above test is especially applicable to rotary converten, the belt being
discarded, and the a e sides bmng connected by wires ; thus the first ma*
chine supplies alternating current to the second, which acts as a motor
generator with an output of direct current. The only error (usually small)
I due to the fact that both machines are not running same load, since that
one supplies the losses of both.
Fleaslar'a ModMlcatloa of HfovblMaoB T««t. — In this ease ths
two dynamos under test are connected together by belt or shafts, and ars
A.M.nr
7
7
I
FlO. 12.
driven electrically by an external source of current, say astorace battery or
another dynamo, which is connected in series with the circuit of the two
machines. Figure 12 shows the connections for this test, which will be found
carried out in full in Fleming's '* Electrical Laboratory Notes and Forms."
Motor Teste.
Probably the most common method of testing the efficiency and capA>
city of motors is with the prony brake, althougn in factories where spars
dynamos are to be had, with load ayailable for them, there can be so
MOTOR TESTS. 396
qMBtion Uiat b«lUiig the motor to the dynamo -with an electrical load ia
by far the moet accurate, and
L I t the easiest to carry oot.
t t f » briA* teat. — In
this test a pulley of suitable
dimensions is applied to the
motor-shaft, and some form of
friction brake is applied to the
puUcT to absorb the power.
The following diagram shows
v«>j 13 one of the simplest forms of
prony brake ; but ropes, straps,
and other appliances are also often used in place of the wooden brake shoes
u shown.
NoTB. — See Flather, ** l>fnamometer» and the Meamrement of power,"
As the friction ot the brake creates a great amount of heat, some method
of keeping the pulley cool is necessary if the tost is to continue any length
of time. A palleT with deep inside flanges is often used ; wator is poured
foto the pulley after it has reached its full speed, and will stay there by
resson of the centrifuiral force until It is eyaporated by the heat, or the
speed is lowered enough to let It drop out. Rope bralces with spring bal-
ances are quito handy forms.
Tlie work done on the brake per m inuto is the product of the following items:
I = the distance from the centre of the brake pulley to the point
of bearins on the scales, in feet.
n = number ofrevolutions of the pulley per second,
w = weight in lbs. of brake bearing on scales.
Power = 2 V inir = foot-pounds per second, and
wv _2*lntD
^•^— 560
Tbe input to the motor is measured in watts, and can be reduced to horse-
power by diTiding the watts by 746 ; or the power absorbed by the brake
esD be reduced to watts as follows : —
If the length, /, be given iu centimeters, and the weight, 10, be taken in
grams, the power absorbed by the brake is measured directly in
ergs, and as one watt = 10' ergs, the
Watts output at the brake = —.57 — = -P-
p
The watts input = Pt and ei&ciency in percentage = ^ X 100.
If the output is measured inlzs: feet and fo=z lbs., then
P = 2.72»Iir.
Pi
Input in horsepower = ^^i
2irlniff .
Output in horsepower = — and
BAciency in percentage = 100 . A^.
If it is desired to know the friction and other losses in the motor, after the
brake test has been made, the brake can be removed, and the watts neces-
•sry to drive the motor at the same speed as when loaded, can be ascertained.
Clsictrlcal l««d Uittiincluding loss in belting, and extra loss in bear-
ings due to puU o/beli).— This test consists in belting a generator to the
motor and measuring the electrical output of the generator, which added to
the friction and other losses in the generator, makes up the load on the
motor. The efflciency is then measured as before, bv the ratio of output to
input. The great advantage of this form of test is, tnat it can be carried on
for any length of time without trouble from heat, and the extra loss in
bearings due to pull of belt is included, which is therefore an actual com-
mercial condition.
I
396 TESTS OF DYNAMOS AND MOTORS.
In thto form ol test the losset in the generator are termed eomnier torque,
and the method of determining them is given following this.
CoMBter torq««t— In tests of some motors, espeicially indnotlon mo-
tors, the load is supplied by belting the motor under test to a direet current
generator hairing a capacity of output sufficient to supply all load, inclndiqg
orerload.
In determining the load applied to the motor and the counter torgme, it is
necessary to know, besides tne /. S, or watts output of the generator, tlie
following : ~
T^R of generator armature.
Core loss of generator armature,
Bearing and orush friction and windage of gonerator^
Extra bearing friction due to belt tension.
It is necessary to know the above items for all speeds at wbloh the
bination may have been run during the testing. This Is especially useful
in determining the breakdown point on induction and synchronous motors,
both of which can be loaded to such a point that thev ** fall out of step.**
While the motor is under test especial note should oe made of the speeds
at which the motor armature and generator armature rotate, and of the
watts necessary to drive the motor at the various speeds without load.
The eownter torque will then be the sum of the following three items : —
P = i* J2 of generator armature,
p0 =: core loss of generator armature,
J^= bearing and ornsh friction and windage of the generator armature.
The field of the dynamo must be separately excited and kept at the same
value during the load tests and the tests for " etrap po»er,*'^ and does not
enter into any of these calculations.
JBclt-on tmmt, — After dlsconneotinff current from the motor under
test, and with the belt or other connection still in place, aupplv sufficient
voltage to the dynamo armature to drive it as a motor at the speeds
run during the motor test, holding the field excitation to the same value as
before, but adjusting the voltage supplied to the armature for changing the
BDeed
Take readings of
Speed, i.e,, number of revolutions of dynamo armature,
volts at dynamo armature.
Amperes at dynamo armature.
Oonstruct a curve of the power required to Mre the eomblnation at the
various speeds shown during the motor test.
Relt-oir teat. —Throw the belt or other connection off, and take read-
ings similar to those mentioned above, which will show the power neoeesary
to drive the dynamo without belt. ^ ^
Then for any speed of the combination the " itray power** will be found
as follows : —
P, = watts from helt-of curve, required to drive the dynamo as a motor.
P„ = watts from lelt-^m curve, required to drive the combination.
P« =r core loss in dynamo armature.
^ = friction of dynamo ftel<-e>^. ,. , - ...^ ^ ,.
F, = friction of motor under test, running light and without belt.
y''= Increase In bearing friction of dynamo, due to belt tension.
f-zz increase in bearing friction of motor, due to belt tension.
From the 6eW-o^ curve,
P.zzPc + F 0)
From the beltrcn curve,
P„:=P, + F'\-F,+/+/, A
INDUCTION MOTORS.
397
Ssbtraet (1) item (2)
P,,'-P. = F,'^/+A
(3)
Tlie Talnet of / and A eannot be determined aeonntely : but If the ma-
ehinM are of aooat the same sise aa to bearings and weights of morlng
parts, it is Tery close to eall them of equal ralue, when,
/ or/^ = ^
(4)
The friction F, of the motor under test has been prerionsly found by
Bocfng the watts necessary to drire it at the various speeds. If it is an iii-
iiacHen motor, the Impressed voltage is reduced very low in determining
ttM friction in order that the core loss may be approximately aero.
As sll the Talnes of the quantities on the right-hand side of the equation
(^ are now known,/ is determined, and may be added to P^ to give the total
"tlnui power.** A curre is then plotted from the ralues of ** $tray power '
at diiferent apeeds.
■
Qmmier torque = (P, +/).
Total had=i IJB + PR+ (^/ +A
vbare IJS = watts load on the D. C. machine when it is being driren by
tha motor.
tba motor.
US=:P, +/= " stray power,*'
Total load = /JP + /*ii + '9.
then
TkeTalueof/is so small when compared with the total load, that any
■itaary error in its determination will be unimportant.
VMt of MU'm^UWkmtHwrmj Hotova.
Tha **pmHping-baie1k *' test, as described before, with some little modiftca-
tkm aenres for iesting street-railway motors. The following diagram shows
tba arrangement and electrical connections.
The motora are driren mechanically by another motor, the input to which
k a meaaure of the
loiMa, frictional, oore
loMea, sears, bearings,
ate., in the two motors ;
tlis two motors are
Mueeted in series,
ttroqrii a booster, B,
cira Deing taken to
nuke the connections
In luch a manner as to
bare the direction of
rotation the aame ;
and their voltages op-
POriag
SUPPLYING CORE
L088E8 AMD Fmcmi
8UPPLYINQ
VM.
Fici. 14. Diagram of connections and
ment of street-railway motors.
arrange-
AflMlnies are taken and the efficiencies are calculated as in the " pumping-
WFtSt.
In eliminating the friction of bearinffs, etc., and of the driving-motor, it is
'Ui ftrat without belts, the input being recorded as taken, at the speed
itoceiBary. The belt is then put on and a reading taken at proper speed,
vlth beta the motors under load.
The load being adjusted by varying the field of booster B, the total losses
otttie ayatem are then IB from booater plus the difference between belt-on
'Mding with full load through the motors, and belt-off reading as noted
(allowance being made for onange of I*R of driving-motor). If the two
motors are similar, half this value is the loss in one motor, from which the
sfBdeney oan be calculated as previously shown.
* ~ — In addition to the tests to which the D. G. motor
398 TESTS OP DYNAMOS AND MOTORS.
b oixUnarily submitted, there are seyeral others usually applied to the in-
duction motor, as follows : —
ExciUUUm; Stationary impedance ; MaxUMun output; and some Tarlations
on the usual heat and emoiency tests.
Excitation: This is also the test foroore loss^- friction, allowaiie« beioff
made for / *R of field ; with no belt on the pulley the motor is run at f nfi
impressed voltage. Kead the amperes of current in each leg, and total
watts input. The amperes give the excitation or " running-light*' oorrent,
and the watts g^ve core loss + friction -f- /'J7 of excitation current.
Stationary impedance: Block the rotor so it cannot move, and read volts
and amperes in each leg, and total watts input. This is usually done at
half voltage or less, and the current at full voltage is then computed by
proportion. This then gives the current at instant of starting, and a meas-
ure of impedance from which, knowing the resistance and core loss, other
data can oe calculated, such as maximum output, efficiency, etc.
Maximvan output: TnU might be called a orecuc-down test; as it merely
consists in loaiung the motor to a point where the maximum torque point is
passed and thus the motor comes to rest.
Keep the impressed voltage constant and apply load, reading volts, am-
peres In each leg, the total watts input, and revolutions ; also record the
load applied at the time of taking the input. Then take countet: torque as
explained before, from which the efficiency, the apparent efficiency, the
power factor, and maximum output are immediately calculated.
IIe»t t«a*.— Bun motor at full load for a sufficient length of time to
develop full temperature, then take temperatures by thermometer at the
following points : —
1. Room, not nearer to the motor than three feet and on each side of motor.
2. Surface of field laminations.
3. Ducts (field).
4. Field or stator conductors, through hole in shield.
6. Surface of rotor.
6. Rotor spider and laminations.
7. Bearings, in oil.
During heat run, read unperes and volts in each line.
IMcteiicy t«at. — Apply load to the motor, starting with nothing birt
friction ; maxe readings at twelve or more intervals, from no load to break-
down point. Keep the speed of A. C. generator constant, also the impressed
voltage at the motor.
Bead, Speed of motor.
Speed of A. G. dynamo.
Amperes input to motor, in each leg.
Volts impressed at motor terminals.
Watts input to motor, by wattmeter.
Current and volts output from D. G. machine belted to motor.
Counter torque as explained above, and excitation reading watts.
From the above the efficiency, apparent efficiency, power factor
— P*^ -^~ ? ) , and maximum output can be calculated.
real efficiency /
In reading watts in three-phase motors, it is best to use two wattmeters,
connected as shown in following sketch : —
1, 2, 3, are the three-phase lines leading to the
motor.
A and B are two wattmeters.
6 is the current ooil of A, and h^ of B.
a is voltage coil of A, and a^ of B.
The sum of the deflections of A and B give total
watts input. At light loads one wattmeter usually
reads negative, and the difference is the total watts.
Resolts* — At the end of the preceding tests the
following results should be computed, and curves
plotted mm them.
^ « % synchronism = ^55*^B2*2I21i??-
Fig. 15. ' Synchronous speed.
(
"^
BYNCHBONOU8 HOTOR.
Tarqa»fWDiid> poll at 1 n. radln* =
- iboTB r««QltB
n tnm Stelnmai
ee gliDlUr to Fig. le,
Tia. IS. CtuVH of rwultiottnta of Induction motor.
■7wkr*B««B H*tar. — Synchronoiu moton ^re senaratelT eiclted,
"olUaD.C. exciter ihould hme Its qu»lLtI« tostert u a djnamo. Bjn-
'"MOMmotorBsretffliledforflrrai-iJoimpoinf,- Starting Burr«iiBt dlffer-
W polali of locatioR of th« ntor ; Lrait rxciUnn carrenltor T&rtoug lowls.
AU Ukh Id Bddillon to the regulitr emciencT and other testa. Core loHei,
™a<. />JI loHea. etc.. can be foond by any of the usnal methods pre-
"OMlT dwertbed.
Bnatdmm point. SjnehrnnoiiB molore have but little etartlng-lorquo ;
™ " li n9««ftry to rtart them without load, throwing It on gradaally
«Biii.motorhMMittled>te»dlly and irlthonf hunting'- on lu lynehro-
""■ ipBHl. The bresk-Jown point Ii found by applylna loud to the point
■bnihemotor fall! outor>tep. which nil! be Indlnaled by a violent rash
«nrnnl Id Che ammeter simultaneous witb the I'luving dovrn.
TUtlsPtlsusnaUy carried out at abonl half vnltage.fiie ratio of the load
°;a|eniotor»t the moment of dropplnr out of Ble|, will be to the full load
« htak-down aa Ihe square of the vollngcs, the load being adlualed at
"otaiim Input In each case. For eiample. say a certain motor, built to
"""WOO Tolta, breaks down at IBO K.W.. with an impraued Toltue of
Wn. Tlienllu true foil brea)t.dowii load will b«
i
i.oon' _
K.W.
Dai
flel
400 TESTS, ETC.
Starting ewrrent. Owing to ooiueqaent dbturbanoe to the line, tt Is dani-
rable that the starting current of a sTnchronoos motor be out down to the
lowest point ; but it is difficult to reduce this starting current lower tbaa
200% off ull-load current. A synchronous motor also starts easier at certain
positions of its rotor as related to poles. With the rotor at rest, and the
location of the centre of its pole-pieces chalked on the opposite member,
the circuit is closed, the impressed voltage Is kept constant, and the current
flowing in each leg of the circuit is read, and the time to reach synchro-
nism. Care should be taken to note the amount of ttkeftrstrush of current,
and then the settling current at speed.
Lecut exciting eurrent. The power factor of a synchronoiis motor will be
100 only when, with a given load on the motor, the exciting current is ad-
justed so that there is neither a leading nor lagging current m the armature.
Sometimes It is desirable to produce a leading current In order to halawe
the effect of induction motors on the line, or inductance of the line itself.
This is done by over-exciting the fields.
With fL given load on the motor, the 100 power-factor is found by coin-
aring the amperes in the motor armature with the exciting current in the
_eld. Starting with the excitation rather low, the armature current will be
high and laggmg ; as the excitation is increased, the armature eurrent will
drop, until ft reaches a point where, as the excitation is still increased, the
armature current begins to rise, and keeps on rising as the exciting current
is increased, and on this side of the low point the armature current is
letiding.
With no reason for making a leading current, the best point to run the
motor at is, of course, that at which the armature current Is the lowest ; and
at that point the power-factor is 100.
SrncliroMom Insp«d»ac«.— The EJBC.F. of an altematixig dynamo
is the resultant of two factors, i.e., the energy E.M.F. and inductive E^Ji.F.
The energy E.M.F. may be determined from the saturation curve by run-
ning the machine without load, and learning the field strength necessary to
produce full voltage.
The inductive E.M.F. is at riffht angles to the energy B.M.F., and Is de-
termined by driving the machine at speed, short-circuiting the armature
through an ammeter, and exciting the field just enough to produee full-load
current in the armature. The amount of field current necessary to produee
full load is a measure of the ifufuclire E.M.F., which can be determined ftom
the saturation curve as before, and the resultant E.M.F, will be
Besultant E.M.F. = Venergy E.M.F.* -{■ inductive E.M.F.*.
•tttvratloa teat.— This test shows the quality of the magnetic <Ar^
cult of a dynamo, and especially the amount of current necessary to saturate
the field cores and yokes to a proper intensity. In this test it is Important
that the brushes and commutator be in good condition, and that all oontaets
and joints be mechanically and electrically tight.
The dynamo armature must be driven at a constant speed, and the leads
from the voltmeter placed to get readings from the brushes of tixe dynamo
must have the best of contacts.
The fields of the dynamo must be separately excited, and most have in
the circuit with them an ammeter and rheostat capable of adjusting the
field current for rather small changes of charge.
The armature must be without load, and a voltmeter must be connected
across its terminals.
Should there be residual magnetlBm enough In the iron to produce any
pressure without supplying any exciting current, such pressure should be
recorded ; or perhaps a better way is to start at zero voltage by entirely
demagnetizing the fields by momentary reversal of the exciting current.
To start the test, read the pressure, due to residual magnetbm if not de-
magnetized, or if demagnetized, start at zero. Give the fields a small ex-
citing current, and read the voltage at the armature terminals ; at the same
time read the current in the fields, and the revolutions of the armature.
Increase the excitation in small steps until the figures show that the knee of
the iron curve has been passed by several points ; then reverse the operation,
decreasing the excitation by like amounts of current, until zero potential is
reached.
This is usually as far as it Is necessary to go in practice ; but occasionally
^
RB8ISTANCE OF ARMATURE. 401
It li well to oompleta the entira magnetio eyele by Mrenlng tho ez«itiBgeiii^
not, and lepeaong the steps and readings as abore described.
The readings should be plotted in a cnrre with the amperes of ezeitiag
eurrent as abedasae, and rolts pressure as ordinates.
The E.M.F. will be found to inerease rapidly at first; and this increase
vill benearlT proportional to the exciting current until the ** knee ** in the
enrre is reached, when the E.M.F. increase will not be proportional to the
excitation until after the ** Jntee" is passed, when the increase in E.M.F.
vill again become nearly proportional to the excitation, but the increase
will be at such a low rate as to show that the magnetic circuit is practically
ntnrated ; and it is not economical to work the iron of a magnetic circuit too
fir aboTe the knee, nor is it expedient to work it at a point much below the
"faiee,'* except for boosters.
The excitinig current must not be broken during this test, except possibly
at lero ; nor must its Talue be reduced or recededf rom in case a step should
be made longer than intended. Inequalities of interval in steps of excit-
iBf eorrent will make little difference when all are plotted on a enrye. For
tke same Talue of exciting current the down readings of E.M.F. will always
be Ugher than those on the up curve.
MmaUimm^m of fleUI coils.— The resistance of the shunt fields of a
dynamo or motor can be taken in any of the usual ways : by Wheatstone
bridge ; by the current fiowing and drop of potential across the field termi-
Bals ; and it is usual, in addition, to take the drop across the rheostat at the
now time. The resistanoe of each field coil should be taken to insure that
•U are alike.
Besistanee of series fields, and shunts to the same, must be taken by adif-
faent method, aa the resistance is so low that the condition of contacts may
vary the results more than the entire resistance required. The test for re-
riitekoe of armatures following this is quite applicable. Of course any test
for low resistances is applloable ; but the one described is as simple as any,
•ad quite accurate enough for the purpose.
Mesistaaca •€ »msatnre. — In order to determine the I*R loss in a
ffBaerator or motor armature, its resistance must be measured with oonslder-
aUe eare ; and the ordinary Wheatstone bridge method is of no use, for the
nsson that the Tarlable resistance of the contacts is often more than that
of the armature itself. The dr(^
■Mthod, so useful with higher re-
tltitiaee derices. Is not accurate
caoBf^ for the work ; and the storaqe .
nost accurate method Is probably battery :
Uiedirect comparison with a stan-
dard resistance by means of a AojurrASLEi
pod galTanometer and a storage RESiSTANCi \
Clean the brushes, commutator resistanoi
Rirfaee, or surface of the col- a
)eetor>rittgB, and in the case of a
D. C. machine, see that opposite FlO. 17. Diagram of arrangement for
brushes bear on opposite seg- measuring resistance of armatures.
Bents.
Connect tbe galvanometer and Its leads, the storage battery and resis-
taaeee, ss in the following diagram. The standard resistance, R, will ordina-
rily be about .01 ohm, but may be made of any size to suit the circumstances.
Toe storage battery must be large enough to furnish practicallv constant
current during the time of testing. The galvanometer must be able to
■tand the potentials from the battery ; and it is usually better to connect in
Mries with it a high resistauce, so that its deflections may not be too high.
The deflection of the galvanometer should be as large as possible, and pro^
portional to the current flowing. The leads a, a,, and b and &i, are so ar-
laased with the transfer switch that one pair after the other can be thrown
in (nrcuit with the galvanometer ; and it is always well to take a deflection
lint with B, tiien again after taking a deflection from the armature.
The leada a and Oj must be pressed on the commutator directly at the
bnish coataeta, and may often oe kept in place by one of a set of brushes
at either side.
Test.— Close the switch, k^ and adjust the resistance, r, until the am-
meter shows the amount of current deured, and watch it long enough to be
402
TESTS, ETC.
rare it is oontteat. Oloae the transfer switeh on b and 6|, and read fhe fil-
▼anometer deflection, oalling it d. Throw the transfer switch to the eo»>
tacts a, and a,, read the gaWanometer deflection, and call it d,. Transter
the contacts back to b, and fr| and take another reading ; and if it diffen
from di, take the mean of the two.
Let X = resistance of the armature, then
*= B^.
a
NoTB. — See Fleming*s ** Electrical Laboratory Notes and FomiB.'*
Teats for Faulta la Amata
STonoEnxrrrcw
The arrangement of galvanometer for testing the resistance of an armap
tnre is Uie very best for searching for faults in the same, although it is not
often necessary to measure resistance.
T«tst for opciB circBlt. — Clean the brushes and oommutator, then
apply current from some outside source, say a few cells of storage battery
or low pressure dynamo, through an am-
meter as in the following diagrams. Note
the current indicated in the ammeter; ro-
tate the armature slowly by hand, and if the
break is in a lead, the flow of current will
stop when one brush bears on the segment
in fault. Note that the brushes must not
cover more than a single segment.
If on rotating the armature completely
around the deflection of the ammeter does
not indicate a broken lead, then touch tiie ter-
Fio. 18. Test for break in ar- ?»n*^» <>' t^« galvanometer to two adjaoent
mature lead. hunt working from bar to bar. The defleo-
tton between any two oommutator bars
should be substantially the same in a perfect armature ; if the deflection
suddenly rises between two bars it is indicative of a high resistance In the
coil or a break (open circuit).
The following diagram shows the oonne^y
tions.
A telephone receiver may be used in place
of the galvanometer, and the presence of
current will be indicated by a " tick '* in tha
instrument as circuit is made or broken.
Toat for abort circuit. — Where two
adjacent commutator bars are in contact, or
a coil between two segments becomes short-
circuited, the bar to bar test with galvanom-
eter will detect the fault by showing no
deflection. If a telephone is used, it will be
silent when its terminal leads are connected
with the two segments in contact. See dia-
gram below for connections. If there be a short circuit between two coils
the galvanometer terminals
should include or straddle three
commutator bars. The normal
deflection will then be twice that
indicated between two segments
until the coils in fault are
reached, when the deflection will
drop. When this happens, test
eacn coil for trouble ; and if indi-
vidually they are all right, the
trouble is between the two. The
following diagram shows the con-
nections.
tvro. — Place one terminal of the
galvanometer on the shaft or
Fio. 18. Bar to bar test for
open circuit in coiL
SHORT coMurr
BETWEEN SEQMENTfl
OR IN OOIL
.StMAOa ■HUMT **
^TTEBY
9n. 20. Bar to bar test for short eir-
enit in one coil or between commuta-
tator segments.
frame of the machine, and the other terminal on the commutator. (Ihm
ARMATURE FAULTS.
403
9agt battery, ammeter, md leads most be thorotghly insulated from
mL) If, DUDder these ctronmBtancee, there is any deflection of the gal>
pNseter, it indicates the presence
.** STOfUdC
Shimj
Fig. 21 . Alternate bar test for short
circuit between sections.
p fmuuf , or contact between the
Imre ooaductors and the frame
ifte machine. More the terminal
Mt the eommntator until the least
pKtioa is shown, and at or near
liinist will be found the contact
[lie particular eoil connected be-
ns two segments showing equal
■etian^ unless the contact happens
dose to one segment, in wnich
will be aero deflection.
^ ID field coils can be located
method. The following
I riiowB the connections.
tfarmatitre qf nmUipolar dynamo U electricallp centred, put
down brushes 1 and 2, and take rolt-
age of machine ; put down brush 3,
and lift 1, take voltaae again ; put
down brush 4 and lift 2, again tak-
ing yoltaee; repeat the operation
with all the brushes, and tne volt-
age with any pair should be the
same as that of anv other pair if the
armature is electrically central.
The same thing can also be deter-
mined by taking the pressure curves
all around the commutator as shown
in the notes on characteritUei on
dynamos.
T«8t for ground in armature
coils.
As tbore the brushes should be exactly at the neutral point.
(
ALTERNATINGh-CUBBENT MACHINES.
RaviasD bt E. B. Raymond and Cbcil P. Pools.
Fob altematlxig or periodically yarying oorrents there are three Talon at
the E.M.F. used, or of which the ralue is required :
a. The maximum value, or the top of the urare.
6. The instantaneous value of a point in the wave.
c. The effective E.M.F., or Vmean* value of the full wave.
Since the maximum value of a sine curve = | x its average value, the
maximum value of the E.M.F. of a single-phase hi-polar alternator pro>
ducing an alternating sine waye of E.M.F. Is
_ V • jy^ 2 r.p.s. ^^^^ w* Ift r.p.8. 10^
2 q q
In an alternator having p poles and m phases,
w Jfc ♦ N9P r.p.s. IIP*
2 mq
where X; is a number ranging from 1 to 2.5, depending upon the shap^ of the
coil of the armature ana al«> upon the shape of the pole-piece. iv« = nnm*
her of conductors ; q == number of paralleT paths in each winding or phase 1
The instantaneous B.M.F. in one winding at any moment
- ' V ^'«Xr.p.s. x»XPX*i<r< .
-gX — ^ Xsinf,
where 9 = the angle through which the armature has turned from the posi-
tion where the coil embraces the maximum flux. The most important value
of all is the square root of the mean square value of the sine wave of KMJF^
since this value is the effective or working value. It is equal to the maxi-
mum value of a sine E.M.F. wave -f- V2,
Hence
_ w *»^«p r.p.s. 10-« l.llh*jrtpT.pjk.Vr*
2 V2 mq mq
In lAree-^Aoss alternators the E JIC.F. between terminals will depend upon
the method of connecting the armature conductors. The two most common
methods are called the delta connection and the Y or star connection, both
shown in the following diagrams.
DELTA OONNECTMMI Y OR STAN OONNECTIOII
Flos. 1 and 2. Values of E.H.F. in three-phase connections when x =: y = s.
In the delta-connected armature the E.M.F.'s between terminals are those
generated in each coil, as shown in the diagram.
In the Y-connected armature the E.M.F. between any two terminals is
the E.M.F. generated by one of the coils in that phase multiplied by the Vi
or 1.732.
Two-phase circuits are sometimes connected as a three-phase circuit ; that
is, both phases have a common return wire. In this case the pressure be-
tween the two outgoing wires is V2 x E^ and the current in the oomraca
return will be / V2, both conditions are on the assumption that E and / hi
each phase is the same.
404
ENERGY IN THREE-PHASE CIRCUITS.
405
kolst
bcsmat from an alternator depends npon inductance and reeietance.
reoeSeient oC inductance 1b represented by the letter L. The B.M.F.
. alternator follows approximatelr a sine curve, and the cnrrent from
>y the same kind or curre. Since in a circuit, lines of
in proportion to the current flowing, at each of its different our-
tnere is a new value of lines in force. Thus, in a circuit of
J current there is a continuously raryiug flux, and hence there is in-
1 a back £^.F. This back B.M.F. is called the back E.M.F. of self-
. and it retards the current flow Just as does resistance,
back £J(LF. of self-induction combines with the reBistaiioe» but at
lassies thereto, the result being called impedance.
tsodBciant of self-induction =r
msiC. flux X t«rn« ^ ».«««„
^ = amperes XIO* -^"^^^^
I multiplied by 2 v / = reactance ohms (/= cjcles per seoond).
a cireuit where R = resistance ohms, ana 2 n fL = reactance ohms.
MBbiiie at right angles to produce impedance ohms, or the total
foree of the current, thus:
Impedanoe = Vjp-4-(2»/Z)2.
b an alternator circuit if the coefilcient of self-induction of the
be X, and that of the external circuit be £, ; and If the resistance
sltemator armature be J2, and that of the external circuit be ^ti
eSeetiTe E.M.F. generated in the alternator armature =: J?, then
flowing will be
itir«lj' ]f«M-Iad«ctlre aaiA 1
Three«Pliaii« Otrcolt.
.•.Mknrtm, dl.c»m of . TH«mn«rt«l m-ltiphMO ^n,r.tor and olr-
Cj =r E.M.F. of any phase in the armature,
i, =: current of any phase in the armature,
B = E.M.F. between mains,
/ = curroit In any main,
Fig. 3.
Py = power of one phase of the armatursi
P =r total power,
P = 8 »t = ^^= 1.732 EI,
/=
1.732 ir
.406
ALTERNATING-CURRENT MACHINES.
In the following diagram of a delta-conneoted polyphase generator
eirooits, let
/> = 3P, = ?J^ = 1.782 JP/,
1.732 f
Fio. 4.
Where the olronit is indactive, in order to determine the teal power the
above result must be multiplied by the " power factor.*' or theoosine of Uwj
** angle'* by which the current lags behind or leads the E.M.F. Thus tw
power in a circuit in which the current lam 9 degrees behind the E.M.Fr^
IE cos 9. If the current lags W^ behind the E.M.F. there will be no energf
developed as cos 90^ = 0. {
The cosine of the angle of lag «, or the power factor, is equal to the ratii^
of the true watts to the apparent watts. In ordinary lighting dlstributioafel
the power factoi* is high so that rough calculations are made without Hij
▼alue being exactly known.
Aarl* of Iifici V« AeteraslMe with a watt aseter ta tlm**^
pluwe drcaita (Fig. 6) : Connect the current ooU in one lead ; oomwtt;
Wm
Fio. S.
one end of the potential ooil to a; on the same lead ; now eonneet the r^
maining end first to one of the remaining leads y , then to s, calling the fint
reading Pj and the second, Pjj ; then if 9 = angle of lag,
When 9 is greater than 60 degrees, one reading will be negative, so tbst
the difference of readings will to greater than their sum.
If JR= resistance per leg of T-connected armature,
r= resistance per phase of A-connected armature,
then,
PR loss in Y-connected armature =8 l^R
I^R loss in A-connected armature = 3 (tt^V = Pr.
CHrcaifa.
■aerfy ta Hoa«ladactlTe Vlirea-
/ =■ current in any one of the three wires of external circuit,
« = current in one phase of the armature for delta connection,
7>= watts output oi a balanced three-phase generator,
1.732= VJ,
.STTzzl-i-Va,
£=Tolts between terminals (or lines) on either delta or Y svstem,
v = volts of one phase of the armature if connected in ** Y,*'
22= resistance per leg, of Y-connected armature,
r= resistance per phase of A-connected armature,
P^Z /, © = ^-^jz^-^r B 1.732 (either with Y or A armature).
COPPEK LOSS IN ARMATURES.
407
lor A
P=3r,i=zSv, 4=
3X1
*.* P = — T— ^ = 1.732 K /, whioh shows statement in brackets to be trve.
V3
J- ^
'"My. 1.738
I, = 1.73S i In delta system.
I^R loss in Y conneeted annatnre = 3 /y*JL
/*i? low in A oonneoted armatnre = 3 ( -^ ) r = /,V.
E
A.
J<'
E
1 1 ■•
t1 ^
E
E-E,
E-E.
FlO. 6.
Fig. 7.
^=V§^,= 1.732^,.
/ JUMPBin - i.7S> X ror 9
/ Aiimu^f
/ AiiP0tES-l.7t>x«ory
/Aipraa-i. Tttx y or •
/ AMKREt-tr
/ ampehes-*
l>elta Connection. Star or Y Connection.
Rhm. Sand 9. Yalnes of current in three-phase connections, where xzzyzr^z.
%m iSkm Amata
A. Ruckgaber
•f AUeimatora.
In the armature of any altemating-cnrrent dynamo or motor of either
■ingle or polyphase the copper loss is always equiyalent to —^ , in which
/= tots! amperes and R = the measure of resistance between leads of a
pluse, osually taken as an ayerage of the measurements of the armature
resifttanee of each phase.
Let H = Resistance as measured (ayerage).
r == Resistance per phase.
/ = Total amperes = watts -7* yolts.
/, =r Amperes per lead.
t ^ Amperes per phase, in winding.
Wkmi^m^
Here /= A = i ; and R-rzr
l^R loss = /»-».
408
ALTERNATING-CURRENT MACHINES.
Tw
(Fig. 10).
E is meMured from 1 to 3 and 2 to 4.
T — ^ — ^'^^^^
JB "" Tolta
i.=i.
Then I*R loss = 2i7«J2
7»J?
31
Fio. 10.
Two-Ph
friMdlnffs CoMBect«4 1m Sert
The/i«-B loB8 = -4i*r =
4/«r
8
TV
2
J2 1b measored from 1 to 8 and 2 to 4,
the arerage of these two being taken
for the yalue of R*
Then
J»=&±4^>=r.
The I^R lose = -5-*
Tlftre«-Pba«e f^tmr GosttectloB (Fig. 12).
Then the I^^R loea = 3 iV = S /i«r = iV.
ii i8 measured from 1 to 2^ 2 to 3, and.S to
1, the ayerage of the three being the value
nsed for R.
Then B as measured =: 2 r.
™^ ,.„, PR
.-. The I^^R loss = -y
Fig. 12.
Three-Pliaae n«l«a CoMMCctfon (Fig. 18).
Then Ii*R loss = 3 iV =
/V
3
i{ is measured from 1 to 2, 2 to 3,
and 3 to 1, the arerase of these being
taken as the ralue of R,
-VVWWWWW>AAA/V\r
r
Fio. 13.
2^
r (r -\-r) 2 I^R
Then R as measured = -^^^i^. = - rand the Ii*B loss = -j—
1
REGULATORS FOR GENERATORS. 409
Tli« General Electric GomiNUiy in October, 1889, placed on tbe market a
lev type of polyphase alternator, which Is claimed to overcome many of
HidfauItB common to the old Btyie of machine, eepecially when oBed on
eomUned lighting and motor loads. While it has been found a compara-
tive] j easy matter to compound and oTer^sompound for non-inductlTe loads.
It has been heretofore quite difficult to add .excitation enough to oomppuna
for indnctiTe loads which require considerably more field current than do
leads of a non-inductive nature.
The following description is taken from the bulletin issued by the makers
[ deKiiblng the machine, which is of the revolving field type : —
I "The means by which this result is accomplished are as follows : The
i daft of the kltemator which carries the revolving field carries also the
i aniutare of the exciter, which has the same number of poles as the alter-
! sator, go that the two operate in synchronous relation. In addition to the
I eommntator. which delivers current to the fields of both the exciter and the
I altcnuUor, the exciter has three collector rings throush which It receives
eorreotfrom one or several series transformers inserted in the lines leading
: from the alternator. This alternating current, passing through the exciter
'■ ■nnatore, reacts magnetically upon the exciter field in proportion to the
rtco^ and phase relation of tne alternating current. Consequently the
Bagaetie field and hence the voltage of the exciter, are due to the combined
«iwt of the shunt field current ana the magnetic reaction of the alternating
evieiit This alternating current passes through the exciter armature in
nek t manner as to give the necessary rise of exciter voltage as the non-
bidietfTe load increases, and without other adjustment, to give a greater
lin of exciter voltage with additions of inductive load."
MBQVMiA^T^mm worn AiiorsRiTATiirc} cujimKirr
General Electric €k>mpany.
Tbk regulator antomatically maintains the voltage of the generator at
ws deeired value by varying tne exciter voltage. Tnls is done by rai ' "
<9«mnf and closing a shunt circuit across the exciter field rheostat. Fig. 14
>(ovi the elementary connections of the regulator. The rheostat shunt
fttvit is opened and closed by a differentially wound relav. The current
for operating this relay is taken from the exciter bos bars anu is controlled by
ueflotting main contacts. The current for oneratins the direct-current con-
tni msgnet is also taken from the exciter bus bars. The relay and the dlrect-
wnnteontrol magnet constitute the direct-current oortion of the regulator,
lid maintain not a constant but a steady exciter voltage. The alternating-
cvrent portion of the regulator consists of a magnet having a potential
^Bdiag connected, by means of a potential transformer, to the bus bars or
tie elrenit to be rMuiated. This magnet also has an adjustable compen-
Htlng winding which is connected in series with the secondary of a current
^BMormer usually Inserted in the principal lighting circuit. The core of
tmi magnet is attached to a pivoted lever carrying a counterweight which is
^VBneed by the attraction of the magnet. If a load is thrown on the genera-
tothe voltage will tend to drop, the alternating-current magnet will weaken
^destroy Oae balance of the core and lever and cause the main contacts to
eloie; this in turn will close the relay contacts and entirely short-circuit
MM aciter field rheostat, thus increasing the exciter voltage until the origi-
ui haUnce of the alternating-current magnet core and lever is restored
^ the altematixig-earrent vmtage maintained at the required value.
Is BOfme eases the exciter voltage will vary from 70 to 126 volts from no
KM to full load. This is especially true if the load is partly inductive
ttd ^e rsffulator is adjusted to compensate for the line loss. In order to
l[tthe fall range of regulation within the scope of the regulator in such
*SM, the alternating field rheostat should be turned entirely out and the
*^ter field rheostat adjusted to lower the alternating-current voltage
wont flSper cent below normal. When the regulator is switched in, it will
CUM tbe rheostat shunt circnit and instantly build the voltage up to nor-
^« and maintain normal voltage by rapidly opening and closing the
rheoftat shunt circuit. --• * f ^ ^ •
(
410
ALTERNATINQ-CURRENT MACHINES.
MAIN eOtfTACTt
0.C.0ONTM0LI
MAONtT-*.
m
POTINTIAL
MNIOSTAT
Tcn^
^=<ouiiMNT mAiiaFOf
rvCOBHS
ntur
A.e. MNUMTOII
<M MAIM
m
HOTOM
Fio. 14. Diagram of Xlrrell regulator and connections for a single genera*
tor and exciter.
AlteimatincwCarrent Amtati
Almost any continnons eorrent armature iHndlng may in m general way
be naed for alternating currents, but theT are not veil suited for suoli work,
and speoiiJ windings better adapted for the purpoee are deeianed.
Alternating current armature windings are open^circuit wmdlngs, exeeot-
ing in the rotary converter, where the rings are tapped directly on to tne
direct current armature windings.
Early forms of armature windings of this type, as first used in the United
States, had pancake or flat coils bound on the periphery of the core, in
the next type the coils were made In a bunched form, and secured in lane
slots across the face of the core. Both these types were used for alngfe*
phase machines. After the introduction of the multiphase dynamo,
ture windings begun to be distributed in subdiyided oolis laid m slots of the
core ; and this is the preferred method of to-day, especially so in the
revolring field mtMshines.
The sinffle coil per pole type of winding gires the laiver E.M.F., as the
coils are thus best distributed for influence by the magnetic field. This type
also produces the hishest self-induction with its attendant disadvantMes.
The pan-cake and aistrihuted^oU windings are much fk^er from Belf-aidn»>
tlon, but do not generate as high E.M.F. as does the single-ootl windings.
In well-considered multiphase windings the E.M.F. Is but little leas for
distributed coils than for single coils, and has other adyantagee, espedaUy
where the use of step-up transformers permits the use of low voltages, and
conseauently light InBulatlon for the coils. The dlstributed-ooil winding
offers better chance for getting rid of heat from the armature core, and the
conductor can in such case oe made of less eross'^ection than would be
required for the single-coil windings.
— nii^ greater numl^r of coils into which a winding is divided, the less will
ARMATURE WINDINGS.
411
be tbe terminal TolUge at no load, Pantaall A Hobart gire tli« following
fatio for termiiial roltage under no-load conditions :
ttnsle-eoil winding =r 1. for the same total number of conduoton, the
•pacing of eondneton being nnlform oyer the whole oircomf erenoe.
Two-eoil winding = .707.
Three-coil winding = .687.
Foiii>-coil winding r= .664.
When tbe armature ie loaded, the cturent in itreectB to change the termi-
nal S.M.F., and this mfty be maintained constant by manipuMtion of the
exciting current. With a glTen number of armature conductors this reac-
tion is greatest with the single ooll per pole winding, and the ratios just
giTen are not correct for full-load conditions.
Mmcle-pksuMi IFImdla^.— The following diagram shows one of the
iplest forms of single-phase winding, and is a iingle coil per pole winding.
Fio. 10.
Another similar winding, but with bars In place of colls, is shown in the
nUowtng figure. It can oe used for machines of large output.
{
Fto. ]&
412 ALTERNATING-CURRENT MACHINES.
Ttia followlnf flgnra ihawi k good (jpe of thrMban p«rpola«:
»
* •rinding tar 4
llowliur dlunm il
. It oIutiM tbe 1
l«>d HlTaoUige, and UappllMbl* (o Miy nombat ol
)dtj^
Flg^ 1tl« a dlaffam of a bar irladlng fOr
bur oondooton p«r pole par phaae.
'lBdlBc>. — Fig. a« li a dbwrun of a tbrM^M*
ARHATUBE WINDINOB.
I vliidliis eoaaacttd In T, lo wbloh ooe aad of «Beli ctf the three vtndlnn
Eli soDBeetfld to > common taimliul, the other endi ly' '-■ —
I tkree eoUeclor rlngi.
■J HiItH nf %tiM tnt*1 iMnJth,
the proDer eudi to sUDUect to tha common terminal and
telbartain mm* be neleeteif u follova: Auume that the cocducCoi
■UdLeolthepole-plecelsurTTlnffthemmxlmur
Hub bj ui arrow ; then the current In the condu
jMiii lo it Till be In the ume dliacUi
amimffrinm the common termlnel, the end toward which the arrow point*
■«tba«nm«tad to ona of therlngi, vhUa the other end is connected to
ikaMmmon termlDftL It [• anlte u evident that the carrenta in the two
Hijaeant coDdnoton mnit be trwjnff <nfo the common terminal, and Ihcre-
ibte tbe nula toward vhleh the arrowi point muat tte connected to tha com-
■OB tariDiiuJ, while their other enda are connected to the remaining two
In a delt* winding, atarthie with tha condacton of one phase In the mid-
Koaaafla^la conductor; then but one-half the aune lalue of current
I
(
It In the other two phuw. a
414
ALTERNATING-CURRENT MACHINES.
and Talae will best be shown in the following dlagrem, In whieh x nuKj
taken as the middle eollector-rtng, and the maximam current to be flo
from X toward z. It will be seen that no e
is coming in over the liney. bat part of the cnrreBfc
at » will nay e been indncea in branches b and e.
Most three-phase windings can be oonneetod
either in Y or delta ; but it must be borne in ntind
that with the same windings the deltapOonnecUon
will stand 1.732 times as much current as the T-
connection, but gives only t-=~ as much voltagew
FI0.2S. Path and Value
of Current in Delta-
eonnected Armature.
«t«re R«SMtl*B «f
AHe
Since the armature core is a part of the magnetic
circuit, and since the armature winding surrounds
thU core and also carries current, It must b« '
expected that this current influences the total magnetism of the macbine J
and hence ita yoltage. This eifect. combined with the natural IndactaDce 1
of the winding, itself constitutes wnat is called armature reaction. Fig. 29
■^
FlO. 23.
shows an alternator in its elements. The armature winding is tapped in
two places and connected to the collector rings d and e, from wmeh the
current flows to the external circuit. This current passing through the
winding on the armature creates a magneto-motlTc force, which tends to
produce the flow of magnetism as shown by the dotted lines a — b—e;
a' — f—e'.OT in a general direction, m—n.
The field current proper entering at A and coming out at B tends to pro-
duct magnetism in the direction a; —y, at right angles to m~n. Under
such conditions, therefore, the ampere-cums of the armature are acting at
right angles to the ampere-turns of the field. This is the condition under
non-inductiye load, the maximam current of the armature occurring in
time and space simaltaneoosly with the maximum E.M.F.
If the maximam of the current of the armature occurs later than the
maximam of the E.M.F., or in other words, if the current lags behind the
E.M.F., the ampere-turns of the armature are no longer acting in a direo-
tion m^n when the current is a maximum, but in a direction m' — n',
partially opposing the main fluxx — y. If the lag of current becomes 90*
the armature reaction would turn still more around, becoming, in fact. Just
opposite tox — y.
Thus, on non-inductive load, the armature ampere-turns combine with the
field ampere-turns at right angles, and with increasing lag show a liigher
and higher resultant until at 90^ las the two combine by direct addlUon.
Just similar to all this is the self-induction component of the armature
inductance. As has been pointed out, self-induction lags in its oppoeiog
1
ARHATURE REACTION.
415
■eta behind tlie oarrent, thus on non-lndootlye load, the oppoainff effect
Elir-lndQction is shown by Fig. 24.
Fio. 24.
Ml a— c = /= theenrrent,
' a— d=: J? = the E.H.F. generated by the revolutioiu of the arma-
ture,
a— 6 £= the reelstanoe drop = IR in phase always with the current,
a— 17 = IX =: the inductive drop 90^ away from the oorrent.
': The resultant of these =r a — e =: ^o = ^^^ total E.M.F. neoMsary to pro>
bse to give the value E under the conditions.
V Am current lags these values are as shown in Fig. 25, the current lag-
FlO. 25.
Ihg behind and E.M.F. bv the angle 9, At VP lag the E.M.F. of self-
woetion is just in line with E^ hence is added directly to give the total
EJfJ. E^ necessary to generate to product B,
Ikos a similarity exists between the armature reactive effect shown in
1^28 and the armature self -inductive effect shown in Figs. 24 and 25. On
ft« aoeoimt it has been suggested by Mr. C. P. Steinmetz that the two
Vihiai be combined into one and the combined value be given the term
"^ndironous impedance.*' This value is obtained in an actual alternator
^ ibort^iireniting the armature upon itself and reading the anipere-tums
k the Held coils necessary to give full armature current, whion is then
^i^nnedin terms of ampere-tnrns. Since on short-circuit the armature
^•rs^oms are exactly opposing the field ampere-turns, this reading
V^ a direct measure of the armature opposing forces, but conveniently
^oafvted into ampere-turns. To calculate from this value the amount of
^^oe-tums necessary in a given alternator to give a certain voltage, pro-
*tN as follows :
Ut A equal the ampere-turns necessary to produce the terminal voltage
' of the alternator when running on open circuit : let B equal the syn-
chnmoQs impedance ampere-turns obtained as above. Then the total
— >pere-tunis required to produce the voltage B on non-inductive load
^'^ J^-\-B^ If the current Is not non-inductive the two values must be
^onMned with pn^Mr phase relation, as shown in Figs. 24 and 26. The
(
416
ALTERNATING-CURRENT MACHINES.
method has been exteiulTely wed and for ordinary deeigne seems »
nsef al one to follow. A designer can calonlate this yalne to a yecy
aoproximatlon, thus predetermining the regulation. It can be seen __
tnlB that a single-phase alternator ^res a pulsating armature reactioai*
polyphase armature ffives a constant armature reaction since it can bes
that at any instant the magnetic resultant of the current is the same.
For this reason, among others, a polyphase alternator is more elBcis^
than a single-phase macnine since the pulsating armature reaction sets i|
eddy currents from its rarlable nature, which increases the losses.
SYlfCHIiOintZBlift.
There are numerous methods of determining when alternators are in sti^
some acoustic, but mostly using incandescent lamps as an Indioatar. -j
In the United States it is most common to so connect up the synchroaiM
that the lamp stavs dark at synchronism ; in England it is more usual jj
have the lamp at full brilliancy at synchromism, and on some aoeounts la
latter is, in the writer's opinion, the better of the two, as, if darkness ia4|
cates synchronism, the lamp breaking its filament might cause the mnrMsn
to be thrown together when clear out of step ; on the other hand. It is soMW
times difficult to determine the full brilliancy. I
The two following cuts show theory and praetice in oonneetins synehie
nizers.
/^
/^
i
a
1
a
b
ft
Fio. 26. Synchronizer Connections.
W hen connected as ahown^ the lamp
will thowJSUl c,p. at tynchronism.
If a and b are reversed^ darkness of
lamp will show synchronism.
Fio. 27. Synchronizer Gonneetionf*
Lamp lights to full c.p. when dgnth
mos are in spnchronism*
Two transformers having their primaries connected, one to the loaded
and the other to the idle dynamo, have their secondaries connected in series
through a lamp ; if in straight series the lamp is dark at svnohronism ; tt
the secondaries are cross-connected the lamp lights in full brilliance sft
synchronism.
me I^lncolB ft jncliroBlser is so made as to move a hand around a
dial so that the angle between the hand and the vertical is always the
phase angle between the two sources of electro-motive force to which the
synchronizer is connected. If the incoming alternator is runnins too fssi
tne hand deflects in one direction, and if too slow, in the opposite airectioo.
Coincidence in phase occurs when the moving hand stands vertically. A
complete revolution of the hand indicates a gain or loss of one cycle in tlis
frequency of the incoming alternator as compared with bus-bars.
SYNCHRONIZING GENERATORS.
417
Bvppose a ■tationaiy coil F, Fig. 28, has suspended within it ft eoil A, free
|o moTe ftbont an axis in the planes of both coils and including a diameter
^ eatik. If an alternating current be passed through both coils, A will
tike np a poeition with ito plane parallel to F. If now the currents in A
lad F be reTersed with respect to each other, coll A will take up a position
180^ from its former poeition. RcTenal of the relative directions of currents
ii A and F is equivalent to changing their phase relations by 180", and
tterefore this change of U09 in phase relations is followed by a correspond-
fag change of 180^ in their mechanical relations. Suppose now, that instead
of reversing the relative direction of currents in A and F^ the -change in
pbase relanons between them be made gradually and without disturbing
Ihe enrrent strength in either coil. It is evident that when the phase
41iference between A and F reaches 90P the force between A and F will
Weome reduced to zero, and a movable system, of which A may be made a
Mrt, is in condition to take up any position demanded by any other force.
Ml a second member of this movable system consist of coil B^ which may
> te fastened ri^^dly to coil A, with its plane 90P from that of coil A, and the
mk of A passing through a diameter of B.
liuther, suppose a current to circulate
Afough Bf whose dlif erence in phase rela-
tire to that in A^ is always 90°. It is evident
•Oder these conditions that when thediffer-
eoee in phase between A and F is 90Pf the
BOTsble system will take up a position
laeh that B is parallel to F, because the
force between A and F is zero, and the force
betveen B and i^ is a maximum ; similarly
vbien the difference in phase between B
and j* is 90°, A will be parallel to F. That
ii, beginnine with a pnase difference be-
tween A ajxaF of 0, a phase change of 90"
vill be followed by a mechanical change
OB the movable system of 90°, and each suc-
eeiriTe change of 90° in phase will be
followed by a corresponding mechanical FiO.28. Lincoln Synchroniser,
change of 90°. For Intermediate phase
relations it can be proved that under certain conditions the position of
equilibrium assamecf by the movable element will exactly represent the
JMttte relations. That is, with proper design, the mechanical angle between
the plane of F and that of A and also between the plane of F and that of B
is alvays equal to the phase angle between the current flowing in F and
thoee in A and B respectively. „ , . ^ . .
As commercially constructed coil F consists of a small laminated iron
fleld-maniet with a winding whose terminals are connected with binding
posts. The coils A and B are windings practicallv 90° apart on a laminated
iron armature pivoted between the poles of the magnet. These two
windings are Joined, and a tap from the Junction is brought out through a
•lip-ring to one of two other binding posts. The two remaining ends are
biwttht out through two more slip-rings, one of which is connected to the
nnuuning binding post, through a non-inductive resistance, and the other
to the same binding post through an inductive resistance. A light
almniniim hand attached to the armature shaft marks the position assumed
bj y^ armature.
nrovcTom typb sinsrcHiftOftcoPiB.
From T%« KUetric JoumcU.
This type is especially applicable where voltage transformers are already
fantalled for use with other meters. As It requires only about ten apparent
watts It may be used on the same transformers with other meters. There
are three stationary colls, N, M and C, Fig. 29, and a moving system com^
prtsing an iron armature, A, rigidly attached to a shaft, 5r, suitably pi^pt^
and mounted in bearings. A pointer, B^ is also attached to the shaft S,
The moving system is balanced and is not subjected to any restraining
418
ALTERNATING-CURRENT MACHINES.
forc«, iQoh as a •pring or gravity oontrol. The axes of the eoil« J^aad
are iu the same Tertloal plane, bat 90 degreee apart, while the axle of Cla
a horisontal plane. The ooils JVand M are connected in " split phase ** r ~
tion through an indnctire resistance P and non-indnotire resistance Q^
these two circuits are paralleled across the bus-bar terminals 8 and 4 of
synchroscope. Coil C is connected through a non-inductive reirist
across the upper or machine terminals 1 and 2 of the synchroscope.
In operation, current in the coil C magnetises the iron core carried
the shaft and the two projections, marked A and ** Iron Armature** In
S9. There is, however, no tendency to rotate the shaft. If current
Sassed through one of the other colls, say if, a magnetic field will be
uoed parallel with its axis. This will act on the projections of the
armature, causing it to turn so that the positive and negative pro|eei
assume their appropriate position in the field of the coil M, A reversal
lO— I OS
Pdnlar-Brt
^baft-B
Iron Amutiara
FfO. 29.
the direction of the current in both colls will obviously not aifect the posi-
tion of the armature : hence alternating current of the same frequency and '
phase in the coils C and M cause the same directional effect upon the^
armature as if direct current were passed through the coils. If current ^
la^ng 90 dsfrees behind that in the coils ^and C be passed through tiie^
eoU N^ it wfll cause no rotative effect upon the armature because the
maximum value of the field which it produces will occur at the instant
when the pole strength of the armature Is sero. The two currents in the
coils M and N produce a shifting magnetic field which rotates about the*
shaft as an axis. As all currents are assumed to be of the same frequency,
the rate of rotation of this field is such that its direction oorresponds witti
that of the armature projections at the instants when the poles induced in
them by the current in the coll C are at maximum value and the field ahlfts
through 180 degrees in the same interval as is required for reversal of the
poles. This is the essential feature of the instrument, namely, that the
armature projections take a position in the rotating magnetic field which '
corresponoa to the direction of the field at the instant when the prolectlons
are magnetised to their maximum strength by current in the coil C If
the freqnwioy of the currents in the coils which produce the shifting field Is
less than that in the coil which magnetises the armature, then the arma-
ture must turn In order that it may be parallel with the field when its poles
^
PARALLEL OPERATION. 419
I
Joe lU muTlimifn strengtii, cooMqnently rotation of its annature indicates
Fa differenee in frequency, and the direction and rate of rotation show,
[THpectirely, which current has the higher frequency and the amount of
the difference.
Maim om tk« Par»ll«l KaBatafl* of Alt«nufctom. — There is
Uttie if any tronhle in running alternators that are drlren hy water-wheels,
oving to the uniform motion of rotation. With steam-engine driren ma-
^iaes it is somewhat different, owin^ to more or less pulsation during a
itroke of the engines, caused hy periodic variations in the cnfc-oiT, wmeb
eaose oscillations in the relatiTe motion of the two or more machines,
•eeompanied by periodic cross currents. Experiments haye prored that a
fllsggisli governor for engines driving alternators in juir^el is more desi*
tibfe than one that acts too quickly ; and it is sometimes an advantage to
9pftf a dashpot to a quick-acting governor, one that will allow of adjust*
BeDt while running, it is quite desirable also that the governors of engines
designed to drive alternators in parallel shall be so planned as to allow of
sdjiistment of speed while the engine is running, so that engines as well as
djiuunos may be synchronized, and load may be transferred from one
nachine to the others in shutting down. Foreign builders apply a bell con-
tact to the same part of all engines that are to be used in this way, and throw
■seUnes together when the bells ring at the same time. These bells would
abo wrre to determine any variation, if not too small, in the speed of the
Mfiiines, and assist in close adjustment.
Haanfacturers do not entirely agree as to the exact allowance permissible
for Tviation in angular speed of engines, some preferring to design their
djinanos for larse synchronizinc power, and relatively wide variation in
ttgnUr speed, while othen call ror very 'Close reg^ation in angular varia-
mi of Mgine speed, and construct their dynamos with relatively little syn-
duonlang power.
I>7namos of low armature reaction have large synohronising power, but if
uodentslly thrown out of step are liable to neavy cross-currents. On the
Motnrr, machines with high armature reaction have relatively little syn-
cfatoDlAng power, and are less liable to trouble if accidentally thrown out
ofEtep.
The uutller the number of poles the greater may be the angular variation
wtTeen two machines without causing trouble, thus low frequencies are
more favorable to parallel oi>eration than high ; and this is especially so
where the dynamos are used to deliver current to synchronous motors or
rotary converters.
8peeifleations for engines should read in such a manner as to require not
Bore than a certain stated angular variation of speed during any stroke of
the machine, and this variation is usually stated in degrees departure from
Aneanipeed.
Tlie General Electric Company states it as follows : —
"We have . . . fixed upon two and one-half degrees of phase departure
trom a mean as the limit allowable in ordinary cases. It will, in certain
^*Mi, be possible to operate satisfactorily in parallel, or to run synchronous
apparatus from machines whose angular variation exceeds this amount,
ud in other cases it will be easy and desirable to obtain a better speed con-
[nd. The two and one-half degree limit is intended to imply that the max-
u&om departure from the mean position during any revolution shall not
cxMed ^ of an angle corresponding to two poles of a machine. The angle
of dreiunf erence which corresponds to the two and one-half degrees of
me variation can be ascertained by dividing two and one-half bv one-half
the number of poles : thus, in a twenty-pole machine, the allowable angular
variation from the mean would be r^ = .25 of one degree."
Some foreign builders of engines state the conditions as follows : Galling N
thenmnber of revolutions per minute, the weight of all the rotary parts of
the engine should be such that under normal loiul the variation in speed dur-
ing one revolution ^"^'""^ *"***' will not exceed ~ - Some state ^ -
N average 250 200
Oadin says : " The rc«ulatlon of an engine can be expressed as a percent-
Sfo of variation frcnn that of an absolutely uniform rotative speed . A close
Bolitionof the general problem shows that 1\° of phase displacement cor-
(
420
ALTERNATING-CURRENT MACHINES.
responds to a speed yariation, or *' pulsation/* with an alternator of two ■
poles, as follows : —
2 75^
In the case of a single cylinder or tandem compound engine *
A cross compound
ft
5.5%
A working out of the problem also shows . . . that no better reaolts are
obtained from a three-crank engine than a two-crank.
The Westinffhouse Company designs its machines with larger syDehro-
nizing effect oy special construction between poles, and allows aomewhat
larger angular yariation, stating it as follows: The variation of the Ay*
■ wheel through the revolution at any load not exceeding 25% overload, shaU
not exceed on&-sixtleth of the pll^h angle between two oouBecutive pc*l«
from the position it would have if the motion were absolutely uniform at
the same mean velocity. The maximum allowable variation, which i» the
amount which the armature forges ahead plus the amount which It h»M
behind the position of absolute uniform motion is therefore one-thirUeth of
the pitch angle between two poles.
The number of degrees of the circumference equal to one-thirtieth of the
pitch angle is the quotient of 12 divided by the number of poles.
The cross currents of alternators can be shown by reference to Fig. 39t
Fio. 30.
6 6
which represents the E.M.F. vectors of two alternators which have swung
apart in phase due to any cause, such as variation in speed of their prims
movers or fluctuations of speed during a revoln-
I tion.
a I b Let O^A = E.M.F. vector of alternator A.
O—B =. E.M.F. vector of alternator S,
As drawn, the vectors are displaced in phase by
the angle 0. When theee alternators are con-
nected In multiple there will be acting between
them the E.M.F. ^ — 2?, or drawn to the center
point O, the E.M.F. O ^ D. This E.M.F. acts
through the two armatures in series, the oireuit
being a — h — c — d, (Fig. 31); the current result-
ing is equal to the volts O — D divided by the im-
pedance of the two armatures in series, which is
equal to
V(/2. + /?»)« + (2 ir/Za + 2 ir/i*)a
where JU and Jtb = the resistance of the two al-
ternator armatures respectively and Im and I*
their inductances.
Since in such a circuit the proportion of inductance is greater than the
resistance, the current flowing from the E.M.F. O — Z> is lagging a large
amount as shown by the line O— C. Hence the £ Jd.F.'s O — ^ and O — J
Fig. 31. Two Alterna-
tors Connected in
Multiple.
ALTERNATING-CURRENT MOTORS. 421
of the alternators proper are In phaae approximately with this cro«B carreat
and henoe onder sach conditions as the figure indicates there will be an ex-
dian^ of energy (since E.M.F. and current are in phase) which is what
actually happens, thus tending to bring the two aitemators together in
phase.
Fig. 32 shows the vectors of two alternators A and B in phase but the
».B
FlO. 32.
IJf.F. 0 — A smaller than the other, O — B, due, for instance, to the field
(A one being weaker than that of the other. In this case there is a difference
of O—D volts to act through the armatures of the two aitemators in
■erics, as in Fig. 31. As shown in Fig. 32 the current from this E.M.F.
O—D bigs 9fP and is indicated by the vector O— C. This current is, how-
«Tflr,90° away from the £.M.F.*s O^ A and O — B of the machine proper
and httioe does not represent an exchange of energy ; therefore, it nas no
tendency to bring the machines together or increasing the dephasing.
It is plain from the foregoing that to connect an idle alternator in
panllel with one or more already in use :
£zdte the fields of the idle machine until at full speed the Indicator
ikovs bns-bar pressure, or the pressure that may have been determined
on as the best lor connecting the particular design of alternator in circuit.
Connect in the synchronizer to show when the machines are in step, at
which point the idle machine may be conneoted to the bus bars. The load
viB now be unequally divided, and must be equalized by increasing the driv-
liVhpower of the idle dynamo until it talces on its proper part of the load.
vsrv little control over the load can be had from the field rheostats.
To aiseonnect an alternator from the bus-bars : Decrease its driving power
ilovly until the other machines have taken all the load from it, when its
lain switch may be opened and the dynamo stopped and laid off.
Ibe single-phaee alternating-current motor has been quite well developed
vuing the last few years, but it has as yet come Into rather limited use.
rbe polyphase motor has come into very general use, its relative simplicity
Aelng a strong feature.
Only the most elementary formulsa will be given here, and the reader is
nferred to the numerous books treating on the subject ; among others,
8. P. Thompson, Steinmetz, Jackson, Kapp and Oudin.
Following is a statement of the theory of the polyphase motor, condensed
from a pamphlet of the Westinghouse Electric and Manufacturing Com-
Ptty.
<
I
ALTERNATING-CURRENT MACHINES.
nMry "Tliecr; of the P*lj|ik«aa Xa<l«(;tl*M 91***r.
ins4ho« magnet bo held 01
be mada to flow about eltherone or the saU ot pole* HparatalT. Che di
will Uke lu poaitlon pumllsl iritta the line* of forua that mar ba flowlB
will be Hen Dj tba following agurea.
U the two Hts of pole* are eiolted at the >ama tima by curreDti of sqnal
■tnngth, tben the needla will take Ita iHHitlao diagonaJlr. half wa; ba-
tween the two aeU of polee, u will be aean by tiie [ol lowing diagnm.
It la now eaiilT coDcelrable that If one of theaa anrrants la gnwiiit
■ttoiuer while thaotheiiaattbeutmeUme
beeomlng weaker, the oeedle will ba at-
trsotad toward the former nnttl it reaohaa
it* mailianm Talne, wheo if tba currants
reached^iU laailmum btsioa to weaken,
and the other cnrreDt having Dol only re-
vaned Ite direction but begun to grow
Itrong. attnota the needle away troTn (be
Brat catrent and In tha aame direction o<
roMIlon. If thig proceea ba aontlnuallr
r«>eated, tba Beedla will eootlnaa to re-
•Dire, and Itt direotiOD of rotation will be
determined b; the '
h»e windlnn, which wt 11 react on tba Said windings, and roUUonwUl
« produced In the core ]uit m It waa !n the eompaM needle. Two cranlu
it right anglea en an engine abaft ara »nnlogoua with tha qnutor-phaia
Vh^owy of the Polyphftafl lAAacitloB M«t«r.
Condensed from C. P. »telnmeti.
id eymbola are uaed for deelgnatlng the parta tod
THE INDUCTION MOTOR. 423
R= stattonaiy part, nearly always oorrespondlng to the field.
Boior ^ lotatiBg part, oorraipoadlng to tlie armature of the dlreot-emrent
Ajaaljtlcttl leummwj vi ]P*Iypkaa« Ijadvctloii Motor.
Let r = resistance per olreult ofpHmory,
Ti = re^tanoe per oircuit oi seoonaary,
being redaeed to primary system by square of the ratio of turns.
Ijet p = number of poles,
X = react anee w. primary t per oirenit,
f Xi = reactance of secondary ^ per circuit.
rsdoeed to primary system by square of the ratio of turns.
list J =: per cent of slip,
I = current per circ
B =z applied E.M.F. per circuit,
J = current per circuit of primary ^
'E.M.F. perc'
Z = impedance of whole motor per circuit,
T^ torque between the stator aud rotor t
f ss freqaetiey of applied B.M.F.
Lst the primary and secondary consist of m circuits on an m phase system.
n := primary turns per circuit,
»!=: secondary turns per circuit.
Let a := — ratio of transformation.
Then
sE
/(neglecting ex. current) = V/ ■ v« i ^/ i^^^ •
_, -,_ mpr^E^B
Torque r^ 4ir/ [(n + ,r)« + *"(uri + ar)»] '
Power - ^^i^'O-'y .
mpE^
Starting current s= i =r ^ *
Starting torque = q(^ X ^,-
Note that the maximum torque is independent of ieoondary reaiatanee r^, m
depends on the tecondary re$iitance» W
sod thus the speed at maximum torque depends on the tecondary retietance*
Current at maximum torque is also independent of secondary resistance.
Hie maximum torque occurs at a lower speed than the maximum output.
A resistance can be chosen that when Inserted in the secondary, the maxlmmq
424
ALTERNATING-CURRENT MACHINES.
torqae will be obtained at startlxig ; that is, the speed at irhioh
torque oooors can be regulated by the reslstanee In the xotor.
ViQ, 36. Torque otmres for Polyphase Indnotion Motor.
Onnres 1, 2, and 3 show the effect of suooesslTe increases of rotor reals*-
anoe, rotor rnn on part of cnrre o-^ ; for here a decrease of speed dne to
load increases the torque.
Spe«id of Indaction Motor.— The speed or rotating Tolooitj of
the magnetic field of an Induction motor depends upon the frequency
(cycles per second) of the alternating current in the field, and the nvaalmr
of poles in the field frame, and may be expressed as follows :—
r.p.m. = reyolutionfl per minute of the magnetic lleld»
p = number of poles,
/= frequency; then
r.p.m. = 120 "^
P
The actual revolutions of the rotor will be less than shown by the formula,
owing to the glip which is expressed in a pero«itage of the actual revoln-
tions ; therefore the actual revolutions at any portion of the load on a
motor will be
r.p.m. X 9l^ due to the part of the load actually in use.
actual speed = r.p.m. (1 — % of slip.)
The following table by Wiener, in the American BUetrieicm, shows the
speeds due to dBf erent numbers of poles at various frequencies.
•poodi of Jtotakry
Field for I»lireroBt ITaasbo
for Vttrioiia JProqvoBcioa.
ra of Poloa
^
Speed of Revolving Magnetism, in Revolutions per Minute, when
li
Frequency is :
Is
j5
25
30
33i
40
50
60
66}
80
100
120
125
133J
2
1500
1870
2000
2400
3000
3600
4000
4800
6000
7200
7500
8000
4
750
900
1000
1200
IGOO
1800
2000
2400
3000
3600
S760
4000
6
500
600
667
800
1000
1200
1333
1600
2000
2400
2600
2067
8
375
450
500
600
750
900
1000
1200
1500
1800
1875
2000
10
300
360
400
480
600
720
800
960
1200
1440
1500
1600
12
2S0
300
333
400
500
flOO
667
800
1000
1200
1260
1383
14
214
257
286
343
428
514
571
686
857
1029
1071
1143
16
188
225
260
300
375
460
600
600
750
900
938
1000
18
167
200
222
267
333
400
444
533
667
800
833
889
20
150
180
200
240
300
360
400
480
600
720
760
309
22
136
164
182
217
273
327
364
436
645
666
682
720
M
125
160
167
200
260
300 333
400
600
eoo
626
66r
1
'
THE INDUCTION MOTOR.
I. — Tlw Mp, or dWoraiM
. lor, 1a da« to tha rMUtuia"
BUp TBrI<« from 1 pw oent In
-wWljrtorti
« of TOteUon betWNO roMitaMi iotd
, J Jaglpiod lor Yuy clou rsgnlatfon
> 40 par cent tn onfl twllj doBicBfld, ordcfllnedfoTH>nieip«cl»l purpo**-
WiiBat (tf as Om fallowing Mbls u embodfln^ Che ufoti TUJUIon* :
O^iHdtrofHotor.HJ.
Blip, at full iMul, p«r oant.
CulUmllik
AY»™^
i
30 tow
30
I
XI
1
» " ao
IS
l'
* " "
U
s
19
s
T » 16
11
T)
' " "
10
m'
*
16
0 '■ 11
SO
4 " 10
ao
8 ■■ 0
e
EO
B
TB
im
1 " «
uo
I |. E
S
a»
3A
300
1 " 3
ud the ■rnuLtore core, or Botor,
The niodins) Id both ettrt an
ud For Ihli reH»a both psr^ ■
Uk meptlon of tha winding
— BoA t1i« Deld-tnms ooro. or SUUor,
built npof Laminated Iron punchLcgi la
■"■--•—"- i.-.—- ,o( either part.
i
,gt. Th«followiiigcul^tak
■anal lorm ol aloii uimL
FiOB. 37 and 88. Forma of Pouchlnga of Indnotlon Hoton.
nu number of iloti Id tbe tliiAn- mnit he amaltlple ot '
aadnnnbet of phaM, and Welaetglveg the following tH
<an EleetrieUD, u inowlng the proper Dombar to be ns
1— i .._ . tiir^^piuua maehlnea. In practice tl
(
u> dealgned m Co be eqnall]' ipiiaed at
li the whole Innef
426
AI/TERNATINQ-CURRENT MACHINES.
9 mf n«ti to VIaM-Vi
Capaeitj of Motor.
Number of
Poles.
Blots per
Pole.
Bloti per Pole per Phue.
TWD^hMO.
Tliree-PhMe.
i HJP. to 1 H.P.
4to<
8
4
J»
1
|H.P.tolH.P.
4to<
6
6
l»
2
4tol0
5
6
?
"i
2 HJr. to 6 H.P.
4to6
7
8
9
3
6H.P.tofiOH.P.
• to 13
7
8
9
4
"i
4to8
10
11
13
1
10 to 90
7
8
9
3
60HJ».to200H.P.
8tol3
10
11
12
18
6
6|
4
<tolO
14
15
16
7
7
The number of nlots per pole per phase in the rotor must be prime to thft[
of the MkUor in order to arold dead points in startingf and to insnre smooUi
running, and commonlv ranse from 7 to 0 times the number of poles, or
any integer not divisible by the number of poles, in the squirrel cags or
single conductor per slot windings. The proper number ox slots may M
taken from the followiug table by Wiener :
^
THB INDUCTION MOTOR.
427
ib«r mi
op to A H.P. Gapacliy.
Number
of
PoIeSf p.
Limits of Slota,
Number
7 p. to 9 p.
Number of Rotor Slots.
4
6
8
28 to 96
42 " 54
66 " 72
29| SO, 31, 33, 34, 36, 37.
43, 44, 46, 46, 47, 49, 50, 61, 62, 63.
67,68,60,60,61,62,63,65,66,67, 68, 69, 70,71.
In larse machines, where there is more than one conductor in each slot
apd fai which the winding is connected In parallel, the number of slots in
toe rotor most be a multiple of both the number of phases and the number
MjuifB of poles.
The following table glTes numbers of slots for yarlous field-slots :
MmwAmr of IKotoiHiloto
for iBdnctloi
over A K.P.
Motors of Cs^iMscitioa
Kmnber of
FMd-SIotsper
Pole.
8
9
10
12
14
15
16
Number of Botor-Slots. (n« = number of
Field-Slots.)
JRu OoMfli^. — This must be settled for each particular case, as it
nU be governed much by the quality of iron and the particular design of
toezaotor.
Hysteresis loss increases as the 1.6 power of the flux density ; and eddy
cvnnt lasses are proportional to the square of the density and also to the
M^re of the frequency.
The following table shows practical ralues :
for IndnctloB
(Wiener.)
GMMdty
<rf
Motor,
Flux-Density, In Lines of Force per Square Inch.
For Frequencies
from 25 to 40.
Practieal
Values.
ISOOOto 18000
15000" 25000
18000" 32000
Arer-
age.
15000
20000
26000
For Frequencies
from 60 to 100.
Practical
Values.
10000 to 15000
1200O *• 18000
16000 " 26000
Aver-
age.
12500
15000
200OO
For Frequencies
from 120 to 180.
Practical
Values.
7000 to llOOO
7500 •* 12500
8O0O '* 17000
Aver-
Age.
9000
10000
12500
(
ALTEBNATING-CDRRENT MACHINES
■1
■■•VnoittM for
Moten-(a>ii«awd
>)■
Flnl-DWMlty. In Una <rf Force per Squre Inch.
C«pMity
For FreqneDole*
trom^Uiim.
fromlGtoW.
IramOOtolOO.
HJP^'
FTMtiail
Ater.
Prutloal
Atw-
PrmoMol
ATar-
V»lu«.
nge.
VHOM.
age.
J
!000ou> Mon
30000
18000 to 32000
25000
9000 h> 31000
uooo
asooo
' 40000
10000 " »ooo
ITBOO
30000" BOOB
M00(
11000 ■' 29000
mo*
10
toouo" eocoo
12S00 " MSOO
9D
soooo" Toooo
60000
16000 II 36001
SO
wooo" aoooo
70000
MCN»
KEOO
100
roooo" 90000
iSOOO
09000
G6000
2O0OO " wou
ISO
wooo" 100000
50000
TOOOO
OOOOO
26000 •' «00»
aoot
OOOOO " 110000
100000
TOOOO
30000 '■ 60000
«w»
I
In tba earlier ind action moloi
to connect the drlrlnB correnC
hlgh]]r Important that
Iha number of wlDdlnga
on (he ralor be prime to
that uf Che italor. Fig. »
otCL-
i.belDgSl.orthrea
Mlator winding!
at either enj to A
copper ring, thti
heavy copper
In the modem ma-
ehinei the winding
■hown would be In coUe
end* being curled to
outalde of tbe machine
Infltead of to rlnm ■■
e laced on the rotor and
9 made of ban ai men-
tioned.
StarMMf ud H«ir-
slaMiMr DwTlcda. — Small
eltj. are alartAd by closing (he c
noton, up to about S h. p. oap*-
:tlj to the motor. In large mn-
if atandlng. and woald act In a
itj of a atatlc tranaformer. and
« method with tbe Oeoetal
ny. A get of strongly conflrucled tealetancfa Ib ae«at
rtnv, and lo arranged with a leTer that they niar be cla
id after the motor baa reached iti toll apeed. These r«l
THE INDUCTION MOTOR. 429
i
rncM are in Che armatoreoirtfaits. In order toglre maTJmqm ttarting torque
ilotal armature reaiatanoe should be
\ Whwe rj = rotor realstanoe per circuit rednoed to fieM system.
Xx = rotor reactance per circuit redueed to field system,
r = reaiatanoe per field circuit.
y = reactance per field circuit.
i Ttdi method serves the double purpose of keeping down the starting cur-
i xtnt snd increaaing the starting torque.
AcaUt«MC«« isi 0t«t«r. — Besistance boxes may be connected in the
ciicults supplying induction motors: three separate resistances in three-
fbase circuits, and two separate resistances in two-phase circuits. They
Hwt be all eonneeted in such a manner as to be operated in unison. Under
thsie conditions the pressure at the field terminals is reduced, as is of course
tks starting onrrent and the starting torqae. In order to start a heavy load,
ader this arrangement, a heavy starting-eurrent is necessary.
CawpsiMasitaM ot A««e-Tni«af<»ms«i«.— This method is greatly
fiTored oy the Westinghouse Electric Manufacturing Company, and is used
extensively by the General Electric Company. It consists of connecting an
iiKptdanee coil across the line terminals, the motor being fed, in starting,
from some point on the windinff where the pressure is considerably less
thaa line pressure. This avoids neavy drafts of current from the line, thus
not disturbing other appliances attached thereto, but as regards starting
eaxrent and torque has the same effect as resistances directly in the line ;
that is, greatly reduces both.
■•(•r WfaMllmn C^a
psrt of the rotor windings are designed to be connected' in series when
■•(•r Wfaasilmn C^nssBntsstod. — In this arrangement all or a
■tsilhig, and are thrown in parallel after standard speed is attained.
Another design haa part of the conductors arranged in opposition to the
raasinder in starting, but all are thrown in parallel in regular order when
nniiing at standara speed. These commutated arrangements have not
hew much used in the United States.
The lioale-phaae alternating-current motor brought out by the Wagner
Beetiie Hannf acturing Company of St. Louis, is, in mechanical construc-
tion, similar in many respects to the two and
three-phase motors on the market. A field is
built up of iron plates very much like ^ of Fig.
40, and an armature core is also built up from
iron plates very much like B.
The field is wound with so-called pan-cake coils
threading through the slots of the punching, as
shown at C, thus producing a magnetic pole of
intensity, varying from a maximum along the
radius x —yio sero along the radius x — z. The
armature core is wound with an ordinary direct-
current progressive winding, connected up to a
commutator in exactly the same fashion as is the
direct-current motor winding.
Pig, 40^ The commutator of this armature is so designed
that it may be completely short-circuited by intro-
ducing into it a short-circuiting circle of copper
B^JDents. When so short-circuited, the winding affords a substitute for the
■qmrrel-cage form of winding, above described, differing from the squirrel
^, in that instead of currents being able to select paths for themselves,
they are restricted to flowing in paths afforded bv the individual coils. The
('Ps^tionof this motor, as stated, is based wholly upon the principle that
sntadoetion motor with a completely short-circuited armature will, when
j9 to the running speed, operate on single-phase current supply in exactly
ue same manner as does a two or -three-phase motor with two or three-
PhJJB current supply.
Ths armature winding is short-circuited through carbon brushes bearing
^KHB^e commutator surface, and the currents flowing in it are generated
^1 uMTOCtion from the fleld. These currents flow out through the carbon
i^vlies either into an outside resistance box, or where a direct short cir-
ALTEHNATINO-CUBRBNT UACBINE8.
one bnub ami back into Of
onlt of tba bnuhM li piorlded, oat tbroturh one bnu
anuatore thrauch tbe otber. By tha thUSng of ttw „
mutator ■nrlaoe, tbaj are forced Uj take audi poaitlou relatiTS Xl .
nellc polaa cif tb« flald, that T«pallant action bMvsttn them and th« pols
of tha field! ta oBected, and rotaUon reaolM. Who ' ' *-
atlalnsd. tba bnuhea are no longer reqnlred and tha i
completetv ahart-olrcnlled, u atated. The -*- — ' -'—
up of ■Biall copper llnki, vhloh Unki, being
ildi ta etiected, and rotaUon reaolta. When muDliig apaed la
. tba bnuhea are no longer reqnlred and the armBtnro wlndl — '-
iletetv ahort-olrcnlled, u atated. The ihortHilroiiltlna ring la i
' aBiall copper llnka, vhloh llnka, being In torn mounted npnn a el
Lltiogbaod, are thrown Into the annular opeulng in the commutator and
br making cloae contaat with the Indlildual eeoraaDti, produce aTarrelTee-
tlTe Bhort-olroultliig of tbe entire armature winding. In the operation of
the motor, It la Tery adrantageona to have thla abort-clrcnltlng operalioB
perforniadeltherat or aUghtlylwloir tbe running apeed, ao tbeee motors an
bnllt Kith an aatomatli: deilte for performing thla operation. This deTka
oonalate of a aet of fforemor walghte acting against a spiral spring. The
aentrlfngal aotloD of tbe weight will, at the proper speed, force tbe iboct-
|)
Fio. 41. Oroae 8eatlan of Wagoer Motor.
eirculting links Into the commutator, agalnai
gramj^FlR.
dinKrnmtnAtlc mnCoT be^nff aliunn aa In the starting
diagram at the right abuwlng the conditinn at tbe aj
attained full rimnTag speed and the cammutstor Is ahoi
:[Ian of the Wagner motor, and the dl
ting condlllon, and U
- -irnialure after It hi
irtHilrcuited.
Alternators are convertlblH Into motors ; and one alternator win run iB ,
synchrontsni wUb another almlliir machine after it Is brought to the asma
apeed, or. If of unlike number of poles, to some multiple of the (peed of the ,
drlleu dynamo, provided the number of pairs of poles on the motor il
SYNCHRONOUS MOTORa.
no. 43. Connsctlcnu ol Winner 9liigl»-Phue Mat
Aflifbla [nto tb'e moltipla. finch motors «fll run u It se4rsd to tbe drlToo ^|
itnuusTu up to tiro or thrsa timta ita Bannk] rull torque or capacitr. ^H
mulfrphMa (TiiehroiMnii nioton have no atutlng-torque, but iTncbronona ^H
BOton for nmltlpbaM clrcnlla will come ap to ijjichroDlnn irllhont mocb V
nd, gMu Kbont left Martloa-torqne, atutlna u Induetiou motora, with ™ I
tluj.«.aelda[isa.
When coDDSOtod to li»a on which are connecMd iudoctlon moton that
ttadtoeatas l^alnK cnrreiiU and low-power factor ot the line, orer eiclta-
tloi ot the ■jncliTOnona motor fields scti In tbe lame manner aA a condenser ^ I
(■aodiieed tn tb« Une, and toida to reatore tbe current to pb»e with the M
ln|niH<l KM.W., and therefore to do away with IndncltTe dlstarbaiHea. ■
rtliaeoeaBarytoproTlde some sonrco from vblcb ma; be obtained con- H
tUDDaiiuTeDtforeisltlnctbetleldsof tbe irnchronaDs motor; and this Is «J
"(tsust dinio bj the nio of a small d. c. dynamo belted from the motor- ^
■Hft, the exeltlns onrrent not being put Into use tudl the motor annalare
nsehis STDBlinHiEm.
In ttartbig ■ ■jnohTownis motor tbe Held li op«n-clrcnlt«d. and current Is
trnsd on the snnatore. lupraetlce, Seldcolls areconnectedlDTarloiuwars .1
h oMats the duinrs otlsdnaed Toltage, and a low reslstunce coll similar M
tBlheseriiBwliidingof thed.cnmcblneissometlmeesoarrangedonthefleld ■
Mm as to gl*a the necewarj reaction for gtartlng. Another waj is to ns« ■
alow-sTSssnre eicltfttlod. and therefore few turns on tbe Held eo!U : aleo ^
O* Held coOs are " split np " hj a switch at starting. The Deld eidutlon li >^
Unwn on after tbe rolstlni part approaches sTnchronlsm, which may be
wUoated br a lamp or other loltable derlce at the operating switchboard.
.CouMerablo care most b« siercised In tbenssotsTnohrouons motors, and
uslt best eondiUoo Is where the load Is quite steady, othsrwlsa they iulro- A
due IndnctlTe effeets on the line tbM ars qaite tronblssome. The Held of M
•Hb a molar emx be adjusted for a wtlcular load, so there will be neither ■
ludlu nor lantng current, but onlty power factor. If the load change*, V
thsnlhepawwfactoraUo changes, nntll thefleld is readjusted; If tbeload
432
ALTERNATING-CURRENT MACHINES.
has b66n leseenod the curreiit will lead, and if it inoreaaes the curreot
lag. If indaotion motors are connected to the same line, with a syncl
nous motor that has a steady load, then the field of the synchronous mot
can he over-excited to produce a leading current, which will conteraet
effect of the lagging currents induced bv the induction motors. If two or n
synchronous motors are connected to the same circuit, and the load on oi
of them is quite variable, and its field is not changed to meet such chi
conditions, a pumping efrect is liable to take place in the other motors,
especial proyfolon nas been made in the design of the motors to prevent it.
is only necessary to arrange one of the motors of the number for preventi
this trouble, but better to make all alike. A copper shield between pol<
pieces, and covering a portion of the pole-tip, will prevent the trouble ;
the Westinghouse £lectric and Manufacturing Company use a heavy eoi .
strap around each pole-piece, with a shoe covering part of the pole-tip iA]
the air-gap.
Tlieorj of the Ayacbroi
Let R = resistance of whole circuit,
L = inductance of whole oircoit,
El r= generator E.M.F.,
E^ =: motor E.M.F.
refultant.
Fig. 43.
Take the origin at 0.
Let B represent maximum value,
t = Instantaneous Value,
«i = Bx sin (« < + i>\n
eg = ^s sin (m < — ^),
where « = 2 ir/, and /number of complete cycles per seoond.
« = *oBln(«« — ^),
where ^ = angle of lag of i7o '^^^'^ respect to the origin.
Bf,^ = £}> + j^a* + 2 BiEt COB 2 ^,
For
cos 1^ =r — i-= — 2 cos ^,
-Co
f.<l;; B\'^'\^*='»^r,^^*,
— ^» — ^\
8ln^=:l^L±S}coe*.
V. If©
B^ and ^ are known,
Energy shifts the origin by the angle ^.
e| = ^ sin <b> < — > ^ + i/f>.
THE SYNCHRONOUS MOTOR. 433
Sow / = ^ *— — »
•od /1«gi behind ^o ^7 ^^ angle 4 where
By intFodneliiff the angle ^ we are referring the E.M J'.'s of both maehinee
to tbe lero pomt of the resultant waye as origin.
Inffemeral
vbere P = the power in watts, and
9 = lag or lead of / with respeet to JS,
E and /are mazimiun Tallies,
T= - f or the periodic time.
lifit A = power giren to the circuit by the generator,
P^ = power absorbed from the circuit by the motor,
Then
TJ^ 2 V jp -f »a /;»
A =^-^=^==[cos (* + *)«>8«-8in (^ + ^) 8in«],
sin « = — » cos * =
•••^^ = 273?M^^ {i2cos(* + ,^)-Z;«rin (* + *)}.
and mbsUtuting — ^ f or + ^ we get
Sow rin,fr = =i£L+^^^,
If,
~ i
BabititQting and redncing
An angle ^i is Introduced such that
sin 3 ^1 = . — f and cos 2 ^i =
1
^
(
ViP -|. mS xs Vip -I- «a X«
434
ALTERNATING-CURRENT MACHINES.
Substitute in P,, and
P, i« a maximum when 2^ + 2^' = W
or
* + *'=4''
that is, the *' sine term " =s unity.
Ps is positiye provided
B,
Et V/p + «az>
the
I.
i
^:2
ncLO
I
Fia.44.
which BhowB that it is possible to hare E^ mater than E^ if there is
proper ratio of resistance and reactance in the circuit.
Kow, if we plot from an actual motor the
armature current and the field excitation we
get a curve shown in Pig. 44.
This shows that the armature current
varies with the excitation for a given load.
The flatter curves are for Increase of load.
Point a shows under excitation,
6 shows over excitation,
c shows the excitation which
makes the power factor unity ; it is well
from the point of stability of operation to
slightly over excite, and this makes E^E* ,
s^ also counteracts the Inductive drop in
the line, thus showing that the action of an
over excited synchronous motor is similar to a condenser.
Graphical treatment.
Eg = generator E Jf J*.
j?«i = motor E.M.F.
E9 = resultant B.M J*.
/• = resultant current.
01§z=. projection of /• on O ^
O Im =: projection of A on O Bm.
O £# =r w# = energy given 19 by
the generator.
OBm = <*«• = energy abaorbed by
the motor from the cir-
cuit.
, is negative, which shows that wm is the
motor, because it is Uking energy from
the circuit f and similarly «■»« is the gener-
ator, because O Eg . 01$ U positive, and
gives up energy to the circuit.
[For further discussion see Jackson'i
Alternating Current and AtternaHna Cuf-
rent MacHtnes; also Electrical Wond for
March 30 and April 6, 1896, by Bedell and
Eyan. The latter is the classic paper on the subject.]
01,
Olm
vuMfovnm
FlO. 46.
OTlTAMOTOIiA.
These are of two styles, one for changing direct current of one voltage
Into direct current of a different voltage, and usually called in America
motor-generators; the second class chanRes alternating current into direct
currSt or vict verta, the voltage not being changed excepting from alter-
nating Vmean* values to direct-current values equal to the top of the
alternating wave ; these latter machines are now called rotary converttn^
and are largely used.
DIRECT-CUREENT BOOSTERS. 435
lyynamoton are now lazigely used In telegraph offices for redncinjr the
preesore of the supplj current to roltages suitable for use in telegraphy
and for ringing and charging generators In telephone offices.
Theory. I/et
B = Toltage at motor terminals.
e = voltage at generator terminals.
/ = current in motor armature.
II = resistance of motor armature.
N* = number of condactors in motor armature.
L = current In generator armature part.
it = resistance of generator armature part.
iv«j=r number of conductors in generator armature part.
-ir-= ^ = eoefflcient of transformation.
S = induced E.M.F. in motor part.
Bx = induced E.M.F. in geuwator part*
K = r.p.s. XN»x^,
B^ = ej- n.Iy
he ^E^kl—krJ^.
If it be assumed that losses by hysteresis and eddy currents be negligible,
or that £/= ftA whence A = it/, then
= f-(«.+lK
Boeh machines run without sparking at the commutator, as all armature
rsaetions are neutralized.
DutKcx-ciJRiftflmr booatsma.
litis Is a trpe of motor generator much in use for raiting or lowering the
pfsssme on long feeders on the low-pressure system of distribution, and is
to be found in most of the larger stations of the Edison companies. It is
also mncb used in connection with storage-batterv systems in charfflng cells.
Hm ^ booster " consists of a series generator drfyen by a motor direct con-
Bscted to its armature shaft. The terminals of the generator are connected
tai series with one leg of the feeder ; and it is obyious that the current in the
feeder will excite the series field Just in proportion to the current flowing,
pnrrided the design of the iron magnetic circuit is liberal enough so that
we field is way below saturation (on the straight part of the iron curve wav
below the knee). As the armature is being independently rotated in this flela,
it will produce an E.M.F. approximately in proportion to such excitation,
which B Jf .F. will be added to that of the feeder or will oppose that E.M.F., ac-
endlng ss the terminal connections are made. On three-wire systems two
generators are direct connected to one motor, and for convenience on one
Ded-plate.
Such a booster can be so adjusted as to make up for line loss as it in-
ersaaes with the load.
One danger of a booster that is not always taken into account is, that if
die sham of the driving-motor should happen to open, or, In fact, anything
should happen to the driving-motor that would result in its losing its power,
the generator would immediately become a series motor, taking current
from the line to which it is connected, and by its nature would reverse in
direction of rotation, and increase in speed enormously, and if not discon-
neeted from Its circuits in time would result in a complete wreck of the
machine. It is always safest to have the generator terminals connected to
their line through some automatic cut-out, so arranged that should
the shunt break, as suggested, it would actuate the device, and automati-
eally detach the booster from the circuit before harm could be done.
436 THE BOTARY GOKVBRTEB.
A rotarp converter is the name giren to a maohine de«igiied for changing
alternatlug currentB into direct currents. If the same maohine be used
inverted, i. e., for changing direct currents into alternating, it is some-
times known as an inverted converter. Again, if the same machine be
driven by outside mechanical power, both alternating and direct carrents
may be taken from it, and it then becomes known as a double current
generator.
Theoretically the rotarv converter is a continuoua current dynamo with
collector rings added, which are connected bv leads to certain parts of tike
armature windings, sometimes at the oommuiator segments.
In the following flgure, which represents in diagram the eingle^kaM€
rotarv converter^ the collector rings r and r^ are connected by leaos to di^
metricallT oppoeite segments or coils of the armature at c and c,. It is
obvious that as the armature revolves the greatest difference of potential
between the rings, or maximum E.M.F.. will be at the instant the segmento
e and c, pass under and coincide with the brushes B and Bi ; and this
E.M.F. will decrease as the rotation continues, until the lowest EJiJP.
will occur when the sennents c and C| are directly opposite the centre of
the pole-pieces P and /*x>
; WTMT OONVUm
Fio. 48.
The maximum alternating E.M.F. will be equal to the direot-euneBt
voltage at the brushes B and B^, and if the maohine be designed to produes
a sinusoidal curve of E.M.F., then the alternating B.m!f., that is, the
Vmean> or effective E.M.F., will be,
V2
where e = Vmean' value of the alternating E.M.F.,
and E = direct-current voltage between orushes.
In a bipolar machine the frequency = r.p.8., and In a maohine with/
poles the frequency will be -^ r.p.s.
Neglecting losses and phase displacement the supply of alternating e1l^
rent to the rings must be / V2 = 1.414 / where / is the direct-current
output.
If, as shown in Fig. 47, another pair of rings be added, and connected to
points on the winding at right angles to the nrst, then another and similar
THE ROTART CONVERTER.
It. wfH ba pmdnced, bnt In qnadntim to ths lint. Tb* B JI.F. will tw
Ptor aaeh phue u In ttas •lD(le-plia«e aoBDMtlan preiioiulv ■hovn,
■cKleedng pbaH dinplHoamsDl mid losHa tbe ourranii wlu b« for
KInta on tko ummtnra wlndlugL ._
^. . , . tlie (ollowlng dlagnun, A Ikmfihatt MiDT*Tt«r li
Fia. «
ibteoBBMUoDaof BfbvMtoM rotoir J ,
_^_j _i.t .1. u__' . DUD t i„„ ^, (ollowim
Ml eoDaator rluf and nentnl point t = —p. = JM X.
Toltaffo bstiriHUi oollsMor linp (i = ^.^ = .011 X.
i
r
438
THE ROTARY CONVERTER.
fl
t
u
B
t
s
e
i
I
fl
1
fl
i
I
fl
d
fl
0
B
fl
phase.
II
I*'
q
•4:
?I«
Hi*
•
«
6
II
•
?
^
U
II
1!
i«
- II
11
I**
•
II
II
i-ii«
•
II
-1?
II
II
II
II
1
II
•9 1.
II
•
II
II
II
Continuous
Current
^
M
Vi4
v4
III
1
•
i
is
3
THE ROTARY CONVERTER.
439
1
Thm TsloM of &M.F. and of omrent stated abore are theoretical, and are
varied In practice by reason of drop in armatnre oondactors and phase
dinlaeement. In conrerting from a.c. to d^s., if the current in the rotary
ii m i^iase with the impressed E.M.F., armature self-induction has little
effect : but with a kuoing current, which may be due to nnder-excitation,
the induced d^. E.M.F. is somewhat reduced ; and if the machine be over-
szeited, thus producing a leading current, the induced d.c. B.M.F. will be
laised. TIm same is the case in oonyertiiig from d.c. toa.c., the a.o. volts
bdng down on a higgina circuit.
The corrections for tne theoretical ratios of Toltages as shown are, first
for drop in the armature ; and second, they hare to be multiplied by the
fseton shown above.
Steiamets satrs that the current flowing in the armature conductors of a
notary is the diif erence between the alternating current input and the cox^
dauouB current output. The armature heatinff is therefore relatively small,
asd the practical limit of overload is Umitea by the commutator, and is
sbssUt far higher than in the continuous current generator.
In nz<i>base rotariee the /'it losses of the armature are but 90 % of the
iwilar i*R loss in the armature as used for d.c. dynamo.
Kapp shows that width of pole-face has a bearing on the increase in out-
pat m a rotary converter over the same machine used as a continuous cur-
net dvnamo. He compares the output of two converters, one in which
tts pole-faoe is two-thirds the pole distance, and another in which it is one-
bali the pole distanee. In sinale-phase converters the output is not equal
to that of the d.e. dynamo, ana two- and threei>hase machines are much
tiffarent.
He |rfves, in the following table, the percentage of d.c. output of what
voQldoe the output of the same machine used as a d.e. dynamo.
{Cos = l
9SLzi S
Cos= .7
(Oos = l
nne^hase {Oos= .9
(Ck)s= .8
T^or (Se? = ^ • • • •
toor-phsse jco8= is !!'.'!!!!'!
Fole-width.
i
i
88%
81
73
63
05%
88
80
70
138
128
117
144
137
126
167
160
144
170
167
153
To find the voltage required between collector rings on rotary con-
Tcrten, when
T= number of turns in series between collector rings,
• = flux from one pole-piece into the armature,
/= cycles per second,
S = required E.M.F.
Ihen
For single-phase and two-phase machines
JB = 2.83r/»ia-«,
For three^hase machines
^=3.e0r/»io-«.
(
440 THE ROTARY CONVERTER.
Ttkt lingle-i^hase rotary haa to be turned up to ByooliroDOiii speed by i
external power, aa It will not start itself.
The polyphase rotary will start Itself from the a.c. end, but takes a
mendous Logging current, and therefore, where possible, It should be started
from its d.c. side.
Hie starting of rotaries that are oonneoted to lines baring lights also
nected, should alway§ be done from the d.c side, as the laxve starting cur-
rent taken at the moment of closing the switch will surely show in the
lamps. Polyphase rotaries are sometimes started, as are induction moiOEBy
by use of a ** compensator.*'
In starting a rotary, the field circuit must be opened until synchronism is
reached, after which it is closed. Tlie d.c. side must also be disoonneeted
from its circuit, as it is obvious that the current produced is altematiK
until synchronism is reached. Care must be taken to keep the field cireott
dosed when tb» d.c. side is connected in parallel with other machines, and
the a.c. side open, or the armature will run away and destroy itself.
As the change in excitation of the field of a rotary chsmges the d.c. voltage
but little, and on the other hand produces wattless currents, the regulation
of E.M.F. must be accomplished by some other method. This can be donehy
changing the ratio of the static transformer by cutting in and out turns as
its pnmary, or by the introduction of self-induction coils in the a.c leads to
the rotary.
The first introduces a complicated set of connections and contacts, but li
unlimited in range.
The second method seems especially suited for the purpose, but is sam»
what limited in range. Theoretically the action is as follows : Suppose the
excitation to be low enough so that the current lags 9QP behind the impressed
E.M.F., the E.M.F. of self-induction laos 90P behind the current, and is
therefore 180° behind the impressed E3I.F., and therefore in opposition to it
On the other hand, if the excitation is lai^e, and produces a leading current
of 90°, the E Ji€.F. of self-induction is in phase with the impressed £3(.F.
and adds itself to it. Therefore, with self-induction introduced In the a.e
lines, it is only necessary to vary the excitation in order to change the coo-
tinuons current E Jft.F. A rotary can thus be compounded by uunjg ^unt
and series field, to maintain a constant E.M.F. under changes of load, the
compounding taking place, of course, in the a.c. lines and not in the field of
the machine, as usual in d.c. dynamos.
In handling the inverted converter care must be exercised in starting It
under load, as it is apt to run away if not connected in parallel with otner
alternators. If they are started from the d.c. side, and hare lagging cur-
rents flowing from a.c. side, this current will tend to demagnetise or weaker
the fields, and the speed of the. armature is liable to accelerate to the dan*
ger limit.
A lagging current taken from an inverted rotary, even after having reached
synchronism, will cause an immediate increase in speed, and if enough lag-
ging will cause an approach to the danger point.
Running as a rotary, and converting from a.c. to d.c, the phase of the en-
tering current has no effect on the speed, this being determined by the
cycles of the driving generator, nor upon •the commutation, simply innuen-
olng the heat in the armature and ratio of voltages slightly.
DoubU-etirrent generatoTi are useful in situations wnere conttnoous cor
rent can be used for a portion of the day and the current transferred througL
the a.c side to some other district for use in another portion of the day,
thus keeping the machine under practically constant load.
The sise of €touhle-<mrrent generators is limited by the sice of the d.c gen-
erator that can be built with the same number of poles as a good alternate.
The heating of the armature depends upon the sum and not the difference
of the currents, as in the rotary ^ and the capacity is therefore no greater
than a d.c. machine of the same total output.
Automatic compounding of double cxtrrent generatore is scarcely feasiUe
in practice, and the field must be very stable, as the demacnetixing effect of
the lagging a.c. currents tends to drop the excitation entire^. Such maehinef
run better separately excited.
BOTART CONVERTER WINDINGS.
no.4S.
flu loUoiriiig dlacnuD ahoin the cDanaotloiu of the thres collector riugi
BtlHeoBtlniioiuourTeDt winding of » Bli-pole d^iiainu. As in the lutSg-
Mi Uia rtugi u-* oooDMted (o pulut« on tha comniutktor Bt nwrlr aqiU-
■Untpdnia.
i
(
442
ROTARY CONVERTER CONNECTIONB.
^
CoMTerters.
In the use of rotary oonverters, two or more of these machines are
times oonneoted in multiple to the secondary of the transfonners, and thdi
direct current leads then oondnoted in multiple to a common bua-har elrevM
aa shown in Fig. 61.
INmATOR
(wmismov)
•TATIO
\msmsmm
mrnmm.
mm vms
rOr rO^
MfTARy ROTMr
3
FlO. 61.
FlO. 52.
With the above connections, currents are often formed in the rotaries that
disturb the point of commutation, and it becomes practically impossible is
adjust the brushes so they will not spark. Rather than connect across fit
the above manner, it is better that each rotary have its own transformer, or
at least its own secondary on the transformer, as shown in Fig. 52.
CvrreMt DeMaltl«a.
Current leads ./hmi brushei to binding-potts, must be ample to produce as
appreciable drop in voltage. The following table gives current densitii^
etc., for brush-holders, conductors, bolted Joints, and switches.
Arer«f« Can«Ht JDe«sitlea for Croaa ftecttOM
Sarfisce of Variowa Blateiiala.
Material.
Square Mils,
per Ampere.
Amperes per
Square Inch.
Cross section
Copper wire . . .
Copper rod ...
Copper-wire cable .
Copper casting . .
Brass casting . .
600to 800
800 " 1,200
OOO " 1/K»
1,400 " 2,000
2,500 ** 3,900
1,200 to 2,009
800 •• 1^
i/no " 1,M
600" 700
300" 400
Brush contact <
Copper brush . . .
Carbon brush . . .
6,700 " 6,700
28,600 " 83,600
160 " Iff
30" «
Switch jaws
Copper — copper . .
Bra» <ar. :
10,000 " 16,000
1 20/)00 " 26,090
67 " lOOl
40 " m
Screwed contact
Copper— copper .
6.000 " 8,000
1 10,000 " 15,000
120 " 90d
67" lOil
THE STATIC TRANSFORMER.
RJEYIBED BY W. S. MOODY AKD K. C. BA^NDALL.
Tbk itatle traiMf onnet is a deTioe med for changing the Toltage and our
mt of an alternating circuit inprcMnre and amoant. It consiBti, emen-
tially, of a pair of matoally inouctiye circuits, called the primarr and
Moondary coils, and a magnetic circuit interlinked with both the primary
and secondary coils. This magnetic circuit is called the core of the trans-
fMtner.
The primary and secondary coils are so placed that the mutual Induction
bctveen them Is very great. Upon applying an alternating voltage to the
primary ooil an alternating flux is set up In tne iron core, and this alteniai-
ng flux induces an £.M.F.ln the secondary coil in direct proportion to the
ratio of the number of turns of the primary and secondaij.
Technically, the primary is the ooil upon which the E.H.F. from the line
orioorea of supply is impressed, and the secondary is the ooil within which
asfaidaeed KMIT. is generated.
The magnetio circuit or core in transformers is composed of laminated
ibeet iron or steel. The following cuts represent aeonons of seYeral dif-
fasDt types of single phase transformers.
_R H
U
_ ■ t
- %^
/ — s
Fio. 1. Gores of some American Transformers.
p » primary winding ; • « secondary winding.
In those showing a double magnetic circuit the Iron is built up through
sad around the ooijs, and they are usually called the *' Shell" type of trans-
{
former.
448
r
444 THE STATIC TRANSFORMER.
Fia. 2. Unfiniibed ukd Fiuiibed Coila liir Cora Type Tnnafanun.
V
Fm. 3. nnnoidied Mid Finkhad Coil* for Bhell Type
Fls.4. SbflllTyp*Tniufonii« Pm.S. Cora TnM TnnatociM I
in FnxMBB of CoDsttuctioa. ip ProceM ofConMnutioD. |
i
DUTIES OF TRANSFORMERS. 445
Thofle huTing a stnsle magnetlo dronlt, and haTing Ihe ooils built aroimd
ttie long portions or Tegs oftbe core, the short portions or yoke connecting
ttMse legs at eacb end, are called ** core " type of transformer.
The duties of a perfect transformer are :
(1) To abeorb a certain amount of electrical energy at a given yoltage and
free aency, Mid to give out the same amount of energy at the same frequency
•nd any desired voltage.
Ci) To keep the primary and secondary ooils completely isolated from one
iDoCher electrically.
(3) To maintain the same ratio between impressed and delivered voltage
al ail loads.
The commercial transformer, however, is not a perfect converter of energy,
iltboiigh it probably approaches nearer perfection than any form of appa-
ntiis need to transform energy. The diilerence between the energy taken
fato the transformer and tluit ^ven out is the sum of its losses. These
kMB«s sre made up of the copper loss and the core loss.
The core lose is that energy which Is absorbed by the transformer when
the teeondarr circuit is open, and is the sum of the nysteresis and eddy cur-
rent loss in the core, and a slight copper loss in the primary coil, which is
IBDenlly neglected in the measurements.
The hysteresis loes is caused by the reversals of the magnetism in the
iron eore. and differs with different qualities of iron With a given quality
of iron, tliis loss varies tm the 1.6 power of the voltage with constant fre-
qsency.
Steinmetz gives a law or equation for hysteresis as follows :
»^a= ^ (»*•••
Wr=z Hysteresis loss per cubic centimeter per cycle, In ergs (= 10~*
joules).
i| = constant dependent on the quality of iron.
U j|^=r the frequency,
y = the volume of the iron In the core in cubic centimeters,
P z=z the power in watts consumed in the whole core,
ihn i>=i|JV K(B»«ia-%
uid ■ =
In the eonstniction, the eore loss depends on the following factors :
Magnetic density,
We^j^ht of iron core,
Frequency.
Qnauty of iron,
^ Thickness of iron,
(fl) Insulation between the sheets or laminations.
The density and frequency being predetermined the weight or amount of
Iron is a matter of design. The quaUty of the iron is very variable, and up to
the present time no method has been found to i^anufacture iron for trans-
bnnen which gives as great a uniformity of results as to the magnetic
ion«s as could be desired.
On the thickness of the laminations and the insulation between them de-
pend the eddy current losses in the iron. Theoretically^ the best thickness
of iron for minimum combined eddy and hysteresis loss at commercial fre-
fiuncies is from JOW to jOV/^ and common practice is to use iron about
JM4'' thick.
The copper loaset in a transformer are the sum of the I*R losses of both
the primary and secondary coils, and the eddy current loss in the conductors.
In any well-designed transformer, however, the eddy current loss in the
nndoetors Is negligible, so that tne sum of the I*R losses of primary and
Meondary eac be taken as the actual copper loss in the transformer.
* Bedell, Kldn, Thomson, Else. W., Dec 11. 18B6.
I
THK STATIC TRANS FOBHEB.
Practice)!* ftll iuoBSHful ialgni ol truuformera ue dal
oieaCer or leu eiunt by the method ol cat uid trT. Emntrl'
■re ul little laloe U the deilgner can obtain data on otber inco
formen for the Hame kind uf work, uid bue Itie oalcolatloiu
aMvatna on the behsTlor of the old irhlle under te«c.
Let S ^ Vmean' of the induced E.M.F.
A = Kctlon or miimetia circuit In aqoare Inolie*.
J/= Frequency In cyclea per ascond.
T^ total luroi of wire In MTlu.
Thenr = — ^ — (1)
ThiB equation ifl baaed od the awunptlon of aalne Tsreof eleetroniotin
force, and li the molt tmporluiC of the formnlaa n*ad in Ui« dealsn of la
al taroBtl as current tranalonner.
By Bubatltutlng and tranipoaing ire oan dariTe an equation Anany oa-
knovn quantity.
Tbni It the TOlla, frequency, and tumi are known, then —
«X W*
W
4.M X^XT
(&'■ A W
iMxffxTx (B'*
■t once the croae aflctlon at Iron nscewaiy tor the
knawn, we b»Te, tmnapoelng eqiutlon (4),
' core, and dengllj ar*
^
FEATURES OF DESIGN. 447
Fig. 6 if ft «iiiTe gtring the total flaxea m ordiiuttas and oapaoitiw la K. W*
M aSticAmm. Thto eonre represents approximately oommon praotioe for a
Hm of lighting transformem, to he operated at 60 oydes.
For anj other frequenoy or for power work, a onrye of total fluxes can be
4nvn after three or more transformers have been oalonlated with quito
fiddy dliferlng eapacities.
MMfetic deiMltlce in the eores of transformers vary considerably
Tith tSe different freqnencies and different designs of rarious makers. The
fnctiesl limils of these densities are as follows:
For 26 cycle transformers from 60,000 to 90^)00 C.G.S. lines per square inch.
For 60 cycle transformers from 40,000 to 60,000 lines per square inch.
For 136 cycles from 30,000 to 60,000 lines per square inch.
Densities for other frequencies are taken in proportion.
Cmrrmmt lieaMdtiea* — Current density cannot be determined except
; Beoonsetion with the coil surfisee exposed for heat radiations, and if, there-
fan, for sny reason, different portions of the winding hare relatively differ-
est smounts of exposed surface, current densities must be adjusted to give
' tqusl best distribution.
FBAXIJltBS OF ]»C9I«ir.
In tiie design of successful transformers the principal features requiring
itUstionare:
(1) Quality of insulation between primary and secondary windings*
(2) Temperature rise,
C3) Regulation,
(4) Efficiencies,
15) Agring of iron or increase in core loss,
(6) Power factor and exciting current,
(7) Cost.
■ KneuilatioB.
. No losture of a successful transformer should be given more considera-
tion tl)sn the quality and durability of the insulation used to separate the
two vindiiigB. Good insulation means few bum-outs and interruptions ojf
Mnrice, safety of customers, and low maintenance. The failure of the
fliwlition is mtal to the primary function of the transformer.
Not onlv must the transformer withstand the strain when first installed
V tcrted by the manufacturer, but during years of continued use after
oast mbjected to frequent overloads and probably high temperatures
BMOort periods.
No msnlating material has been found which fills the purpose outlined
wore BO well as mica, first, because of its l>eing fire-prooi, and second,
Mcauae of its high dielectric strength. In a construction where there are
>o sharp comers to insulate, no insulation can surpass mica.
Next in value as insulators^ are perhaps varnished or oiled cloths. The
^se of such insulation varies greatly, and depends not only u|>on the
luUty of the cloth, but more especially on the qualities of the varnish and
^ oaed in their manufacture. Their particular value over mica is their
mptability for use with coils having sharp or abrupt comers or edges,
^iwr, preesboard, fuller board, or other artificial boards are lowest in
theaeale of insulations, and are generally used not so much as insulators
*> lor mechanical separation. If treated with oil or varnish, however, ^
tliar usulatiDjg value is greatly increased. ^
For very high voltages no better insulator is known than mineral oils fH
I*op«ly refined. Oil-filled spaces insulating great differences of potential ^
•"wl be sub-divided by partitions to prevent bridging of the space by n
eradueting material.
T«aapenit«r«.
ftstwnents regarding temperature rise and method of determining the
isme^mam little unless all the conditions are considered. Measurement
M temperature by thmnometer is superficial and of little value.
'[JjrauiU transformers in which relatively lar^e coil surface results, the
'""VMBMore tise is quite uniform, and there is little possibility of any
I
448 THE STATIC TRAN8PORUER.
locml hifli tompflrature [n uiy pvt of tha vrindinjifl. Tempetmlim a
ured by the rm»l»ri«i method or thermr — "- ' — ~—
ftmp«r«tiire It to prorido Ijboral dueU between ftdiacent poitiozu of the
On lergs tisnafonnen the only •((««!¥« tnetbod of innrinc unilona
. „. — ... . ;j- 111 ■ J,.... between adjacent poitiona of tin
i the core. Such docta (rstlr
perienee hafl ibown their neeeeiitf,
I, trangformen an cnxip^ >■
natural draft and ■elf-cooled oi
~ ' intl DiaR Xtaiura
rhieh the beat ie diani ^ , , _,_
.... circulation of which ia generated by the rin in teniperatnre o( th«
ait itedf. Such traneforoiera are i' — "-■ ' -■ — -— ■-^ -■
are expenuve becwiee of the larte i
Oll-C**led' TruaferKcn. — The oil-oooled (luifbrm
which the heat 'a diiaipated by the oil circulatins throuch the
Fla. 7. 176 K.W. Oil-Iniolated S-
> rapid eoDdH-
udttie umf
OIL-COOLED TRANSFORMEBB. 4
buuiated trmaofomka-, in which tha oil haa flowed in ftud r«pftir«d th*
- —^ '"h wu Un uhaII to Gbiue immcdi&ta '' ~
E may b« elTvctJTcJy Lacrcasfld by m
eomutiom, Ihua lAfg^y iacreaiini
in FliT^S wrVB to lEow the etf«cl
tbi oae of oil- Curre 1 repnAflDts the temperature
mm 5. th* biffheot temperature rise acceoeible lo thermometer,
■no] temperature by roisianoe je shown in curve 4.
TliiM ciovM show very totdbly the value or merit of meanir
tBapntors rise of trauiionura by rceiatance method latbei t
AmDDmeter. Tha dilFer«nc« of temperai
•itb and without oil ai aliDwa in Ibue c>
^b^
.„_. BUffieient rtdiatinj enrfa™
~>wt be had in the tank lo disaipale the heat, it becomes necHsary lo
pievide aniBeial cuewu for awling the Hune. The principKl method*
npkiycd are the useof a forced blast of air and by the circulation of water
tbigu^ (be coils immenwi in oil-oooled transformers.
Tbe brmcr am known u air-blaat traosfortners and the latter as waters
rs have been built, wherein
rilMlf.
ucMdln slzea up lo about 4000 K.V., nsliig
Ab Alr-BlBat Xl«Bs7*raeir, or one In which Tentllatlon and radl-
•noo of beat Is. by means of a blast or current of air, forced through Iho
traasformer eoila and dnre, is shown In Figs. 14 and IS, In this trana/ormer,
ue colli are bnlll op bigh and thin, and asaeinbted with spaces between
Ihni. Ihe^r being forced through these spsces. Thelroncore Is also bollt
P»c^ Thlf atrle ol tranafonuBr has been coaslrucled In sixes op to about
THE STATIC TRANSFOBMEB.
Fni. 11. 200 K.W. n.OOO-Volt OH-IunUUd,
S«lf-CaoliDi Tmuforacr.
WATEB-COOLED TBANSFOEUEBS. 461 I
i\
Fm. 13. Watar-CooM TraiwtoniHr out of Tuk.
^
Fio. 14. 250K W. Singla-PluMAir- Fio. 15. Sectios of Air-Blut I
EFFICIENCIES.
■PTMCIBIf CI ■■.
Tba aSlelenej Dl ■ tnsaformer La ths ntloot tin anlput iraUa totbeinpnt
ra k>M, Thlcb U nuds up of tha hjfltf
THE STATIC THANSPORMER.
'hlla the copper lo«, or ^ff lou, TkrlM u th« iqDkra of the eom
-■ via Moondmry. H«thodfl for dfltBrmtamg mil bha ^
J ... .^_ _>. — jj. uji trwuforaoer tating.
truufonner la lensraliy worked >l
dfltBrmtamg mil bha lo«Ma rnr* folly
^Hrilwd III tba oimpMT oD (ruufoi
la • tarTloe whare a truufonner _ . ^ .-
GODDHted to tbe olreult. w In power work, tha sTengs
>ower worE, uia btotuv or ■■ ■ii-oin vo- 1
Ita lalUoiKJ et&elenoj. B; "kll-da;" sS-
Glanoj I* meknt Uie peroeDUge wbieh the enern lued by tha outomat li <rf
Uia totkl anaitT ■•ot Into the trunf oruer daring twaulf -fonr boon.
In iighHin work tha tmuformgn ttn nanall; aonnaotod to tha Dutoa oc
K. W. CAPACITY
Flo. IS. Compumtiv* tWren of Con Lohm and RapiliAia,
Sbowiog tbe ImprcTement made In Tnuulbmun iroDi
igsTto&K.
AMumln/on iin a^rmge fire hours furflokd the iMai will be fi houn >S
uid M hQun (tors loH. ^%e cslcnIftClDn of the "altdBT" elBdaoeT eta,
tberafore, be made by tbe following forr- "'- '
All^, eneiwwjr - core !«. X M + fJtX 6 ^-ruli lo«l y 6 '
FroTD tbig It <i erldaot that while tor power work or eonttnnoiu full load
day " efficlenoy aerlonaly, vat In the oeaifn of tranafonnen whleh are
worked at full load only a atiort time, bat are alwayi kept excited, a large
core loaa meant a rary low " all-day '* efflolancy.
UAQNETIC FATIGUE.
MAHIIWMG VAnciIJE OB AOHMlTe Or XBOH ASH
•TBBI.
TbefabjMt of Mflnf » of vut importaaoe. Thenmilt of invcatjntiaiH
by PmltmoT Gold^n»«h, Mr. Williun H. Mordey and Ur. B. R. Rougct.
B-A.. lad to tbe following cddcIuuoiu:
fint. There is uaquectiaiubly Boah a phfioomena mg ftcoing. J||
Swond. A great ditfsrance eiiata In tha amnunt of BRring taking placa flj
Third. Thia lnn«iH in the Ion [n a giTcn body a[ Eron ii dapeudeot
nWy oa Iba tsmiwaturca at which it is ouioUuned.
Fosrth. Within ordinarr limit! of tBmperature the tsadency to age ■*
VMt the sroUer the temperature. > jm
TiTih. Bolt ibeet ited b mudi le« aubjeot to ageing than Hft iheet iron. fl
Sith. Sheet ited th&t doea not age materially at moderate tempara- «
tme (below 76° C.) caa be obtaioed, but aJmoat any iron or iteel ages more ^
BeTtttb. The real cauae of agdng has not been djieoTered. Many ftt
I1» lawa goveraiiv it have boen determined, but thare ia much room
ferthgr itudy and Taveatigation.
i
Oi^
CHANGE OF HYSTERESIS BY PROLONGED HEATING. 457
If
Z
%
]
M
I
i
1
«
R
e
}
M
N
S
CO
G«
00
o
!8
Is
O
I
o
S
.a
»
^SS.!
®g2g
•lOQQ 04 'CO •Q<-<
• mSiq to •IQ *IOW)
»o<
SI
i
I 3 ^-^
•O • -OCO W -^ »-l •
j5c5
C5
■d
■ COi
3;5 f
•a
i
• 3 t'-ti
lor^ •00
CIQO
SI
•O'
•I
t
■ 3 ^t?
Ot*f^ 00 'f^ '^ • 00 "Q 'Q
U)(0 to •»-» -CO • CO -^ "^
^ :!2
o
9
;i
t
lib.-**
O 9
f-iC) '^lO iQ 'US CO .« 0000
5°^
)tOO
>0 *0 -Q
:I2 S^
•Oft Oi^
bl-e
1-4 b AS
JScJ
<d
CO«
lO 'OO >OiO • >0 '»0 Q>0
O 't^t^ h>OD ' OO '00 OlOl
s
' 3 >4-t^
<3 1> s ?.
00 'CO
»^H ^ •O)
• • CO ••© • • • .ig •
• ^( * ^4P • • • • ^m
• • f^ *^0 • ■ • "CD
O<-i04 CQ-^O t^ooo Necio fi^fc
<
<
THE STATIC TRANSFORUEB.
The moat ImporUuit t»etor la tha life of ineandnemt lamp* is > lUsd^
Tolto^, and ■ Byfltem of dlitributLoa in wbich tha ngulation of pranure tm
not malnuUned to within 2% u liable to ooiuidenbls raduction in ths lif*
and oaadJv-power of ila lunpa. Fur thie ranvja It a hiEUy unportaat tliaX
the rtffulalioTt, i.e.. tha ohance of voZta^ dua wholly to ohanca of load owt
tha ■eoondat? of a transfonaer. be maiatained within aa dooa liiniti m»
In the desi^ of ■ tnnaformar, aood nrulatloo and low oont hua an ia
diTwit oppoaitLon to ona aoothar whan both ara daairad in tha hifhcat d^
crae. For iastanee, ■agumiDs tha danaitleg will not h« obanted in tha itoa
tha core km ooa-half. The turns of win, howavar. an doubled, and lb*
naotanoa of tha aoili quadniplad, bacauna tha iwiatanM chiuicaa with ttie
aquare of tha turaa ' '—
A wrt- ■ ■ ■
Inted inuHformer, howavar, should siva (ood naulta, both ■■
ioaa and regulation, tha nlatlva valuaa dapcodioc upon tktt
it la to do, and tha aiao td the Iranafon
u that tha deal^a of the dlatrihntlng intem hai gnlte a* mnita
ae madntanMiDe of a ataadr roltase aa doea tbs reffuUUio^ of tbm
I, and tha proper iwleotlon ot the ali« of tranafonnara to b»
When tnnafoimeri were tlnC used It wa* tha ouitom to inpplj one for
Bach bouse, and ■ometlmea two or three where the load was baaT]r. Expe-
rience and tata soon niade It AFldent that the Installation of oi,e larga
irKnitormer In place of seieral ema]] one* waa very muoh mora eoODOmkal
In fl rat cost, running eipi^nsee (cost of power toanpply lon>,and regulation.
'H'liere trans form Bra are supplied one for each bouia, It 1* naceaaarrta
proTlde a CBpacIt; for 1)0% ot the lamps wired, and ollowtng an OTerload of
WH at t Imea. Where one large Iranstornier la liutalled lor a gronpof hoaaaa,
capacity for only B0% of the loUl wired lamps Dead he provided. For red-
deuce lighting, where the load factor Is always Tery low. It Is often beat to
runallneof tecoiidaHss over the region to be served, and ooDnectafew
A study of the folluwlng cunea will show In a measure tbs reantta to ka
curve. Pig. ^, shows the relative ciist per lamp ur unltot Itansfonngra ot |
dllterent o^wlty, showing how much cheaper large ona aia tbaa smiU
no. 3S. BalMlTe Cost ol Trantf ormen of Dlffervnt Oapaeltle*.
id set of curves, (Fig. 23). shows the power aaved at ditferoit
Vnctor is tha ratio of tha actual watts in a line to the voJt
amparea or appannt watta in that line. It is alwj defined as the eoalna td
the ancle at phase displsoemaDt ot the eumot from tha voltac* io tha
loads.
1
SWrxMA TBAIflVOVmB.
^
Fia.M. Sbop TMliic Sat. 0 to 12,
nntM. Soeh iipp«»tu« ■■ «m"'-.ILv
ID tioM th* nu-kiDC pnman. li
0 Volb by 300 Volt SU|M.
— ■— < nC ■ volUfe from 2 to
therefora, lo build luch
THE STATIC TRANSPORUER.
T tiish voltascs, gona hkvinc bean nude lor piuMiuw.
IS 600.000.
.r the Hvsre Daiun
kl tbtx mom thui ol
FM.SI.
mom potantUI (train
pfOTidtti bMw<
typ* ol dvdgn, I
TESTINO TRANSFORMER.
I whJBh an sonneeMd to th* (nuiid
Bdanl from the tftio induosl by tb*
0 typ« ot thii sppliBose, Fin. 24 knd 3B show*
ihoviDi ■ s«t for modentvly hi^ To]tac«,
tbt ontv nrmi<4;i>>] w(y of nHniriiic tiM Ufh potatld pcHrMed hj
y spvL-gap Bhunted uroaa '^' "■ — —'--'- -' '*--
i
Fm. 36. a. K. C. Hi(h Volt«ce Teitinc Brt.
wk-gsp is B«t lor the, desired roltaca by
i
with the ipuk-gap to
It should the potcntikl
■ocuiDulUioii o( bich
THE STATIC TRANSFORHEB.
Mriaa, ud ■ ooDttant et
,_ J mMntaliied In the primary. Thl* Ii ihownb
dlBgrkm In Tig. M. Serin tranetomiera for thie pmrioie ban narer beaa
Terj nooeutol, due M the tnnible aaaud bj (he nae ot poaentUI la tka
TYPES OF TRAN8FOBMERS.
463
MMondary wh«n opened for any caiite. Various derloee (Fig. 38)» saoh u
■bort-cirevitiiis polnto aeparaied by a parmfBned paper, or a reaetife or
ehoUzig-ooll connected across tlie secondary terminals, lutre been Intro-
duced to prevent any complete opening of the secondary by reason of any
defect in the lamp or other deylce oonnected in the circuit.
BeactlTe ooils used as shunt devices hare been used under dUfereat
names; as eompensators, choking coils, and economy colls.
A deyice of this kind has been Introdnced by the Westinghouse Electric
and Mfg. Gompanr, and others, for use in street-lighting by series Incan-
deseent lamps. It is shoim diagrammatioally in Fig. 29. The lamp ia
r^ r^ r°n
CONSTANT
CURRCirr
C3 — CS
1
FlO. 29.
placed in shunt to the coil ; vhen the filament breaks, the total current
panes through the coil, maintaining a slightly higher pressure between its
terminals than when the lamp is burning. It is thus eyident that the regu-
laUon of the circuit is limited, due to the exoesslTe reactance of the coils
vhsn several lamps are taken out of circuit.
Se«BOBB J €7«lla or CoHipesMaiers.
A modifloatton of the above is built bv several companies for use on ordi»
aary low potential circuits, where it is desired to run two or three arc
lampa. It Is a sinale coil transformer, and is shown in Fig. ao, and dlagraro-
nutically in Fig. H, same page. If any lamp is cut out or open-circuited.
D. p. FUSE SOX
COMPENSAXOa
•.^
S.P.SWITCt*
Fio.ao. Arrangement of Apparatus for Fio. 31. Westinshouse Econ-
use of Economy Coil or Compensator. omy Coll, for A.C. Arc Lamps.
the current la the main Hne decreases slightly. As more lamps are out out
the remaining lamps receive less current, ana it is necessary to replace the
bad lamps in order to obtain normal current through the circuit.
THE STATIC TRANSFORMER.
BO deelgned that ttiere li tt IcKkpcv
pkth for th« flux betveen thn pr1mmr7
] wid woondiiry. This la BbDiiii Is (ks
^ diaffnun at a and 6. At opeD BAOODd-
U tlltls or no tCB-
Isakagfl MroH thIapMh, kud If properlj proporttonnd.thU Makagawlll — -
u regnlata tha carrent tn tba MCondftrT, m> tbal It vlU be approilmaulj
throocb tha
there li this k
««a«inU BIsetrtc C*K>titBt CarrCMt TnaasforHen.
irormst thna dncribad hu tha dlaikdTantua that Ita ranlatloB
. . ■« tha dlaadTantua that Ita ragal
la flied far uir tniuformac and ma; mry In tiwuronnsra of tSs
deaion without bht ready loeana of sdjUHtment. The Iranafomier ■>
regiuMee (0' mDitant onrrant oTor bni a llralted nwge Id tha aeeundi
The General Electrie Compuy eomiant-ourrenl tnmsfanner ihovn
Figs. 3E and 38 ia eonstnioted inth movable oeooiuiary ooili. and fixed p
DUUT oihIi.
Fio. 33. Constant-Cumnt Timna-
former ihawing CounterweUht
and PrimRry and SecDodary
Lmda from WindioE-
The weight of the movabia mil i
normal I ull-l»ui, currant the moyah
Fra. S4. Conneotlan* for Altar
Beriaa Encloaed An
■ Syatem, with 80, TS.
Li(h%
lially
IBM 8y»t«n, 1 ,
I Osht Tnnsformar.
larbalanoed. a<
Uiua entirely aulomatic. and is fo
eunant, or a dmiartara from oonatant rjurrent if deeirad.
SBo be adjuatad for ticBctioally eonatsnt ounaat tor pi
.. . T^-<J"Ki
inf the magaetjo repulwoii bctwea
ape are out ol the oireuit. the Id
(Bee Fin, Sfi anil 38.) At mid
a im maximum. The reflulation i
if deeiiadTThatra
Jktku:
TTPE8 or TBAHBrORUKBS. MS
■d to \itb% kub. or for ■ iMaliva ngo-
D luQ load to ligbt kwla. lUi tdf^t-
1
w a obiidsad br diuidna th* pod
i^lbBinmiipendfld. Tbaourvaili
iildWi^i tnoifontier.
^ • * aidcMd in a
m in FU. 37 iliow tbe nags obUinsd
iiuD or ah«l Inn lan^ filled with
t ol the secondary ooib.
1
^
r1»
^
.,.00
;■
asaa
ea
il
TTl
KM
«.
«.
=
LU
2!
ItkS
—
^
"^
!,
T.r
-*-
' '
'
i.,
_J5S^
^*
"ni^ B^tfS^^eed by ■ weifdit ot
25?»'^of IheremtaWr. '^ ^
nfM d the tioib. but alow api:
" - ■•OBJ to
tnuafotmer the moTubls ooll Ig
nnnthtftr Tnnvnhltt OOl], dependioc
<rtant at Btartinc
BSD. '^!s'de™''taiir
type is piBclicslly the ume u that
the nnu atpscity. The pmnr [set
<
THE STATIC TRAN870RK&B.
For Low Toltaie oirmiitt required on ti
ooniUknt-oumnt trmiufonneT Ufl been d ,_.— .. ,
•DimMUd IB Hdee with the line. Fig. 38 tfaom k typical a
Pn-SS. aecdlBtincReMtukeaOaDbrllaDlutMn OeocnlOanalnietionCa.
adopted by one of the leadina nuuiufacturen. It oonriate of ■ lioKle nil of
iDiiUkted wire vruised to indoM more or leai of one leg of > " W^'-ehaixd
magoet ej ihuwn in the foUowini cut. Tlie coi] is nupendcd from one aid
of a law and counterbelnneed bf
■ wd(ht on the other, and m
amaaed that at all poiote of iti
traveTU juM balancea the T«ryiii(
. lie eon with a - —
to optD the circuit. Without ciB>
I rent flowina. the noimaJ poftilion
I of tlw ooi] ■ at the top or oS Ibl
!«■ of the mapiat. When the
■Atdi ii (ioMdr eurreot flowi ia i
the eirsuit (and «oil). and dran j
the ooil down oD the l<c to a poba i
relheeameED- |
hoMa the eorreot BtreOKtbat a pn-
determined point: aa, say, O.S un-
pnjea. . It ia said that thia deria I
vithiD oue-tanth ol an ampere.
Thek»ett-»«h*i*^-.*- i»— «u1 '
i*Aloa>«in
der all eonditioiM ot Iwd.
Ai it I* not always, or *
«t«B, that it u DMenary to i
vide for raculation id ma are _
ndt to (he sitral of ila foD haiL
themakars have adopted the pol-
«..»..._. ley 0* lupplyiDV inrtmnuol* to
Se, "0.1." BerleaA.O.BaBulator. care for but that part <4 the load
that b expected to vary, in lonM
I 10% of the circuit and in othen 7S%, thiu avddinc the ■>— ' *"
T appantua. or for iBBulstion for the total - ^ '
POTENTIAL REGULATORS. 467
TbsT claim nuotba- vlTBntsni in being able to oonnKt tha devioa Id on*
l<« of the neriea cinuit, aod allawing tbe other end of the eireuit to be oca-
w.
(^
1 altonadnc currenl potantUl nculator i» Mgentiall; a tnarformar h»r-
ti pfimarT connened aenoa the tnaini, and iti leooDdair In MHee wf A
nauu. The ■eeondsry ii arranied so that the voLtufe at It* tumiuli
y particular ran^r
Dticrambf Connectiona far Single-Phase Potential Reguiatoi, 1
WeMioshouae Eleo. snd^Ulg. Co.
468
THE STATIC TRANSFORMER.
The MToral different styles of feeder regulators hare been deTisod* differ-
ing in principle of operimonf but all of them hare the primary coU con-
nected across the mains, and the secondary coils in series with the mains.
The " Stillwell *' regulator, which was designed by Mr. L. B. StniweJl, hss
the usual primary and secondary coils, and effects the regulation of the cir-
cuit by inserting more or less of the secondary coil in series with the line.
This secondary coil has several taps brought out to a oommutating swit^
as shown in Fig. 40. The apparatus is arranged so that the primary can
be reversed, and therefore be used to reduce as well as to raise the roltage
of the line. It is evident from an ol)servation of the diagram that if two
of the segments connected to parts of the coils were to be short-cirenited, it
would be almost certain to cause a burn-out. To prevent this, the moTable
arm or switch-blade is split, and the two parts connected by a reaotanoe,
KAPP6 MOOIFIOATION
OP STtLLWlLL REOUlATdl
Fig. 42.
this reactance preventing any abnormal local flow of current during the
time that the two parts of the switch-blade are connected to adiaoent seg-
ments. The width of each half of the switch-arm must of neoeasity be less
than that of the space or division between the contacts or segments.
As the whole current of the feeder flows through the secondary of the
booster, the style of regulator which effects regulation by commntating
the secondary cannot well be designed for very heavy currents because of the
destructive arcs which will be formed at the switch-blades. To overcome
this dli&culty, Mr. Kapp has designed the modification wldeh is shown in
Fig. 42. In this rcoulator the primary is so designed that sections of it can
be commutated, thus avoiding an excessive current at the switch. This
regulator, however, has a liimted range, as the secondary always has an
E.M.F. induced in it while the primary is excited ; and care must be taken
to see that there are sufficient turns between the line and the first contact
in order to avoid excessive magnetising current on short circuit.
Fio.48. Connections for M. R.
Feeder Regulator of G. E. Co.
Fie. 44. Diagram of Con-
nections ox Feeder Po-
tential Regulator.
The General Electric Company have brought out a feeder regulator, in
which there are uo moving contacts In either the primary or secondary, and
which can be adapted for very heavy currents. This appliance is ^plainly
shown In Figs. 43 and 44. The two colls, primary and secondary, are set at
right angles in an annular body of laminated iron, and the central ImqI*
^
THBEB-PHA8B REOULATOBS.
469
tan ii arranced so as to be rotated by means of a worm wheel and
chance in the seoondary voltage, while boosting or lowering th^ line
■ sontinuoos, as is aJso the ohaiwe from boosting or lowering, or
In this re^ilator, the change ot the seoondary voltafre is effected
ngs in Oux through the seoondary ooil, as the position of the
I eore is changed by the turning of the nand wheel and shaft. There
Nfoce, no interruptions to the flow of current through mther the
or seeoodary oous, and the regulator is admirably adapted for in-
It K|^t4ng service^ where interruptions in the flow of current, how-
mtftneous, are objectionable.
Mmwtkrmim Ctvcait ]ft«ff«1aion.
a number of dreuits are run out from the same set of bus bars,
B of each drcoit is prpvided for by the use of a single coil trana-
from TariouB points, on the winding of whioh leads are brought out
^ngaktor head, from which any part or all of the transformer may be
iBtD isrvioe to increase the pressure on the line.
Segwlatonk
Ngnlator deseribed above is suitaUe only for operation on single-
ckcnits. The primary is connected in a shunt and the secondary
vith the circuits to be eontroUed. Two or three-phase regulators
but having either primary or seoondary on the moving
Fm. 45. Three-Phase Induction Potential Regulator.
0 eommonly used. The voltage in such a design is constant in each
of the secondary winding, but by varying the relative positions of
rj sod secondary the effective voltage of any phase of the secondary
^Qfeoit is varied from maximum boosting to maximum low«ing.
to the diagram which remsents graphically the voltage of a
i of the regulator, e o — Generator voltage or the E.mIjP. im-
00 the primary; a o "^ E.M.P. generated in the seoondary coils,
eoootant with constant esnerator ELM.F.; 6' a* » Seoondary XM.F.
with the generator ElM.F.: e' a' » Line E.M.F. or resultant of
E.MJF. and the seconoary E.M.F.
^eoutraetion of the rogulator is such that the secondary voltage o a
e to ssrame any desired phase position relative to the primary Ejif.F.,
iZl^h^oc, etc
>^it8 phase relation is as represented by o f, which is the position
ths north poleo and the south poles of the primary and secondary
"^ sre opposite, the seoondary voltage is in phase with the primary
.■ad is added directly to that of the generator. The regulator is
to be in the position of maximum " ooost." and by rotating the
with refsrenoe to the fields, the phase relation can be changed
ttteot between this and directly opposed voltages. When the
of ths seoondary is directly oppoeed to that of the primary or gen-
[»ite phase relation is as represented by o d in the disigram, while o b
' the phase rdation of toe secondary when in the neutral position.
i
(
r
THE STATIC TRANSFORMER.
SASB TBAirsroBMflma.
immonly uasd "■broad" tot * toaa
, sd into AnKTiao prutig*. Sutt
:• differ UtU« from the liiiclA-phHe deeifiu Bud loay be boiH ia
The tbree^tuae ihell type tnuufonner eonset* dmplv of i
phsM unite ■□ united thet oorundenkble of the iro- '- * —
imiininwij Thi* i* iUuatntad by the lollDwioc ei
dmply of
I in the o
i threfr^hve core type trvuformer eonnrt* oF three ie^e of nimfn jitnan
B treiietoTiaer pidcwl aide fay aide uid united M eithv and by ■ yika
he Hm* sroee •ection m eaoli ancle-phM* be.
mil nil
Fm. tt. OroM BeoUoD of the Oara* and OoUa of Time SiiwIe-PhMa
Air-BIan Transformar*.
Fm. W. CroM Swtioi
jt tha Sam* Coi^i Combined In On* Thi«»-PhaM Ail-
T of a Capacity Equal to the Total OaMwlty at
Tbow Above.
aATlO OF TBANBFOBIUTION.
ATnrfiwlTIi
TiiBilDmien ara unially tniih with both their primary
nih moAd ia two or more ■mUodii in ordsr to faouilats ehAiwv oi timaa^
ttoMioo nUio. Thii iM MpMially uMful irli«r« three trudotman are
■id in a thr««-pbMe ■ystam. Lat
■ — latio of tnuufomiMioii from one seeUoa of hich-t«uiDn ilda
to one aeotion of kw-teoiioD aide, exprtaaed ta an iDta(<r;
''■™Bid« " " " •™ " ' »*"■
imbar of aaetiona io aariaa in eaeh aim of the delta, hiah-
teniioD aide:
fi ud d, bdoK the evmapoDding qnaotitica tor tlu lev-ten^n aidaL
_ H.T. line TolU Ys/S + D
"W* formnik ia applicable to aombinatian Man and daltaa aa wall i
r
472
THE STATIC TaANSrORMBR.
TRAif AfoiKHJBit coiffirscnrjiOHA.
Some of the advantages claimed for alternating current STstems of di^
tribution over the direct current gystems is the facility with which the
potential, current, and phaaeB can be changed by different conneetiotui of
tranaformera.
On single-phase circuits, transformers can be connected up to chany
from any potential and current to any other potential and current; but a
a multi-phase svstem, in addition to the changes of potential and eurreDli.
the phases can be chaiiged to almost any form that may be desired.
Mavl«-Phaa«.
The connections of the
having parallel connections.
a favorite method of supp.^ — v-.^,— « ....^.^ ,,— ^ ...i— «-
three-wire seoondaries. A ti^ is brought out horn the middle of the
Ffo. 63. Arrangement of Balanoinj^ Transformer for Three-
Wire Secondaries.
ondary winding, this tap connecting to the middle or neutral of the three-
wire system. In this way a few large transformers can be connected by
three-wire secondaries in a residence or other district, and will take care of
a large number of connected lamps.
^
ammsmuL
*-»?»•« »tf ■*
wsKn |uiiuiii
y
-O—
FiQ. 55. Sind^e-Phase,
Fio. 54. Single- withThree-WireSeo- Fro. 66. Two-
Phase, ondary, Useful for Phase, Four
Residence Circuits. Wires.
Fio. 67. IbTee-
Wire, Two-
Phase.
TBANSrORHBB CONNECTIONS.
473
a modification oi the three- wire circuits, in which the out-
are fed by a singje tmnsformer. and the neutral wire is taken
of by A balandng transformer, connected up at or near the center of
ibotion. The capacity of the balancing transformer need be but half
taet variation in load between the two sides.
makers of transformers have the connection board in their trans-
ao mmngfid that the two primary coils may be connected either in
paraUcs by mere ehangw of small copK>er connecting links, so
amaMB transformer can be connepted up for either 1000- or 2000-volt
and the secondary for either 50 or 100 volts.
or
The plain two-phase or qaarterwphaae oonneetiop <Fig. 56) is simply two
' nuiaformerB oonneoted to their respective phases, the phases oeing
tirely separate. In the three-wire quarter-phase circuit, one of the
'b« used as a oommon return, as shown in Ffs. 57.
. three-phase connections shown in diagram 58 are known as the
eonneetions, and are of great advantage where continuity of service
important. The removal of any one transfonner does not interrupt
^
JL JL-I
twwilaml
Fio. 58. Three-phase
Delta Connection.
Fio. 59. Three-Phase
Star Connection.
the thive-pliase distribution, and the removal of two transformers still
of power transmission on a single phase of the circuit.
Y or star connection, as shown in diagram 50, has one of the
of each primary and secondary brouffat to a common oonnec-
tMm, the rwnaining three tenninals being Drought to the main line and the
distributing lines. The advantage of the star connection over the delta con-
aeetion is. that for the same transmission voltage each transformer is wound
for only 50% of Che line voltage. In high-voltage transmission this admits
of mncli smaller transfonaen being bult for mgh potentials than is possi-
ble with the delta eanneetion.
i
r
474
TH£ STATIC TRANSFORMER.
MC«BieB« of TnMsformen for Atopptar Up
for Iionc IMsteneo XnuumlMlon.
Figares 60, 61, and 62 show diagrammatioaUy tbe oonnectioiis for
threo-phase transmission to quarter-phase generators, with luterchang*
and non-interohangeable transformers.
VCKUUTM
mr w
i;::a»«/uJ ™
iCBwn (VlffVn rvwmn nuMroMaKP
V- - —in
Fio. 60. Changing Quarter-Phase to Three-Phase,
Non*InterchangeaDle Ste{>-up Transformers.
QENeRATOfi
OCNERATOR
jjUJjulAMfl
[
V
Fio. 61 . Ghangiiiff Quarter-
Phase to Three-Pnase, and
back to Quarter-Phase.
All Transformers Inter-
changeable.
Fig. 62. Changing Quarter-
Phase to Three-phase. All
Step-up Transformers Inter*
changeable.
^
TRANSFORMER CONNECmONS.
475
A rotmrj oonrarter wound for 8lz-phM« has a RHMter oapaolty for work
tfaa sAiDie machine wound for three-phaae. Three-phaao tranamlasion,
-er, is rery economical, and in Fin. 63 and M is ahown a dlamm by
•iz pbaaea can be obtained from three phasee by the use of only three
haosformers.
Each transformer has two secondarv coils. One secondary of each trans-
temeriaflrsteonneotedinto a delta, then the remaining secondary coils are
WWWWVA/V wwvwvvw wvwvwvJ
^/vw^^
l^^/^AA^J^/VV^/sA..p/sA/VV^
/WVA/^ /SAAA/>^ AAAAA
Six-Phase A
Figs. 03 and 64. Three-Phase to Six-PluMe Connection.
oooneeted np Into a delta, but In the reyerse order of the first delta. This
is sn MuiTalent of two deltas, one of which is turned 180° from the other.
Is the dlagrmm ABC represents one delta, and DBF the other.
Fio. 66. Diagrams of Connections for Changing from Three-Phase to
Six-Phase.
In the same way the two seoondaries can be connected up T, and one
T turned l$fp to obtain six phases. The disadrantage of Y connec-
tion, however, is that in case one transferrer is burned out, it is not possl-
»!• to Qontlniie mnning, aa can be done with delta connections
476
THE STATIC TRAN8FORMEB.
Meth'
»rcMu
Wwi^^ VM^KMAMf
Fig. so. Two>Pha«e.
wvwvw^vw^rJwM^wwww
AvwvAa>a/\
2
"VvyvAW'
IlG. 68. Three-PbweJ.
Vwww^^ w^ammM^ Uwvm^^
Fio. 70. Six-Phase I>iameUio«l.
pAVNAA/WV\2^AAAAAAA^
AAAAfVWNA K/yWWVV
Mrs t#
Uwwwww Umvmww Wmmmv
f3
kwVWAAAAAMJ/VNA/Vil
IflO. 67. Three-PhAM A.
Fio. 6B. Three-Pbue Y*
^fMMfMl wNmMi Vmmim
1.3
lv\A/V^yAAAVSMf>NAAA/)
Fig. 71. 8ixrPhM«A.
P.I.Kttllf VWWWVWVVv* vVWWIVvVv
V//W^^» ^^A/W^a l^AAA^M^
VNAAA /W\AA A(W\A
Pig. 72. Siz-Phase T.
Fig. 73. Siz-PliaaeY-
GONVEBTER AND TRAN8F0BMSB CONNECTIONB. 477
l...Jl.iJu^
I I >1 .■■r"TSasgi
Fio. 7L ThrM Transfonnen Arranmd in Inter-oonnected Star, Operatiiig
a n&ree-PhaM Botary Conrerter on a D. C. Throe- Wire System.
The** Scott" eonnection is used a great deal in transmiwions and dittri-
bataoiifl (See Fig 75.) One transformer is designated the nuun, and the
other the teaser. Two transformers are required. They are made exactly
•Eke, so that with proper connections either nuty be used as main or teaser,
ns winding is provided with a 50% tap and with taps so that 86.6% of
U» winding may be used. 1-2-3 are three-phase voltage, A-A' one-phase,
B-Bf the other of the two-phase circuit. Keference to the small diagram
rinws the jeaaon for using 86 6% of ^lindins of one transformer; also the
ity lor the 60% tepT
Tco^er
Mafn/OOX
iooT
Fra. 76.
Fio. 76.
ASHBiiro PowvR wm aix-phask cMncrrxTS.
478
TH£ STATIC TRANSFORMER.
A comtsonoir of vmambwo
(F. O. BlaelnraU. Trmns. A. I. E. E., 1Q03.)
AMmninc that three trmnsfonneni are to be uaed for a three-phase pow
traaamiwion and that the potential of the line is settled, eaoh of the "~
formers, if eonneoted in Y, must be wound for —jz or about 58 per esnt of
the line potential, and for the full line current. If eonneeted in A, eaea
transformer must be woimd for the line potential and for 68 per eent of ths
line current. The number of turns in the transformer winding for Y
connection is, therafore, but 68 par cent of that required for A oonneetioa*
to avoid eddy current losses that occur when the cross section of the eoa-
duetor is too lai^e.
The Y connection requires the use of three tranaformera, and if aa^
thing goes wrong with one of them the whole bank is disabled. With tia
A connection, one of the transformers can be cut out and the other twa
atill deliver three-phase power up to their full oapadty; that is, two-tbirai
of the entire bank.
Fzo. 77. Step-down Transformer for 4000 Volt Y Diatribaftioa.
Combined three-phase transformers are generally of small aiae, and on
that account are preferably Y connected on the high poten^al side.
«rowi«lMc tlie ireatraL
If the common connection of transformers joined in T is grounded, the
potential between windings and the core is limited to 68 per eant of that
of the line.
Under normal conditiona, the potential between any conductor of a
three-phaae transmission circuit and the ground is 68 per cent of the lias
potential, with either Y or A connection, but the neutral may drift ao as
to inoreaae the potential with an ungrounded ayatem. If *^ ^ ^ ''
')
Fm. 78. Step-down Tranaformer for 200 Volt Y
partly or completely grounded, the potential between the other two braaefaca
and the ground is, of course, incrMsed and may be the full line pTTtfffti»>-
With a grounded neutral Y system, a ground is a diort dreuit of the traoa-
foTBierB on the grounded branch, and the tranamiaaon beoor^-* ' ^-^
CONNECnON OF TRANSFORMERS.
479
^
, Firoiii the poiai of view of nfety to life and unvtoiion of fim this ia •
iannble oonoitioii, wpaoiaUy if the low tenaioii dSetribution ie aiao grounded,
i If the high tenaiott oireuit iD*kee eontact with the ground or low potential
tgftUan, it can be immediately eut out by funs or automatic eirouit breakers.
; The difficulty is that a power transmission with grounded neutral b
^ikdy to be frequently shut down by temporary grounds, such as would be
icsosed by a tree blowing against one of the wires. E>ven if the circuit is
'set opsned, the drop in the pressure due to the sudden "short" on the
fine will eauee synehronons apparatus to lall out of step.
If two tTmoaformers are oonneeted in series, there is no certainty that
ttey will diTifde the potential equally between them. A ssrstem in which
•B the electrical apparatus is oonneeted in Y has somewhat the same char-
aderistics. The neutral mAv drift out of its proper place and there will be
■Bsqosl potentials between it and the three conductors of the eirouit, due
to nequal loading and differences in the transformers or transmission or-
aits. Such unbalancing would cause unequal heating of the transformena
sad if a four-wire three-phase system of distribution were employed, would
Mciooriy interfere with the r^ulation of the voltage. If transformers,
tlMrcibre^ have Y seoondaries, it is desirable that the primary should be
A eonneeted. Two systems in common use with which A primary wind-
Off ihould be need, are shown in Figs. 77 and 78.
The high potential windings of transformers are necessarily of hif h
nsetance, and if left in series with a circuit of large capacity, as shown m
FipL 79, 80, 81, and 82, the leading changing current flowing over the react-
■nee may set up extraordinarily high pressures. Figs. 70 and 80 represent
Y-sonaeeted banks of three transformers each connected so as to cause such
Fia. 79.
Fio. 80.
tnae of potential. In Fig. 70 the primary of one transformer is exdted by
scaerator, the primary of the other two transformers being open-cireuited.
u Fig. 80 the primary of one transformer is opai-eireuited, the other two
wing eonneeted to the generator. Figs. 81 and 82 show T-conneoted banks
« two transformers, wiiich might be used to transform from either two-
phsis or three-phase to thre^phase or vice versa, and are simibu' in action
to Fig. 70. If m anyone of figs. 79t 80. 81 and 82 the secondaries are con-
asetea to a long distance transmisrion circuit, a pressure of many times the
aocmsl potential will beset up between A and B.and between^ and C, that
Mtwen A and C not bong affected.
It is theoretically possible for a potential 100 times that for which a trans-
fanDSr is wouiid, to be caused by opening the primary switches of one or
more of the ttanafomiers of a bank connected in Y before the secondary
■witdies are used. Actually, the current jumps across the insulation at
some point in the system before there can be any such increase in pressure.
If thfiie are a number of banks of transformers in parallel, this olkenomenA
osmot occur except when all but one bank are disconnected. This source
of trouble coukl be obviated by emptying oil switches on the high poten-
,1
/
480
THE STATIC TRANSFORMER.
tial aide which disoonneet the line before the low tension switdias
iiBed, or by triple pole switches on the primary which open all three
of the bank of tnuo^onners at once.
The selection of Y or A connection of transformers for long
Fig. 8i.
Flo. 82.
transmissions should only be determined after a careful oonaidemtion of
the conditions in each case.
There is little choice between Y or A without a grounded neutral.
NoTB. — For further information on this subject 'see discussion on this
paper in Proceedings of A. I. E. E. for 1903.
iAMs EUBCTRf c coimPAinr ansiftciT]
ARC
■WWWVWWAr
TRANeFORMVR
J
(By P. D. Wagoner.)
A detmled idea of the operation of the mercury arc rectiBer drcuit may
be obtained from Fig. 83. Assume an instant when the terminal H of tbi
supply transformer is positive, the anode A is then pontive axui the are is
free to flow between A and B, B being the mercury cathode. Followiiig
the direction of the arrows stiU further the
current passes thro^^ the load J, thioqgh
the reactance coil £ and back to the iM«a-
tive terminal O on the transformer. A little
later, when the impresaed dectromotrre
force falls below a value suffident to mminr
tain the arc against the counter elcctio-
motive force of the lu-c and load, the
reactance E, which heretofore
charging, now discharges, the
current benug in the same direetk>n
formerly. This serves to maintain the are
in the rectifier until the dectromotive force
of the supply has passed thitray^ aeit^
revcroce and builds up to such a value a»
to cauae A* to have a sufficiently posHjve
value to start an are between it £od the
mercury cathode B. The disehavge eireuit
of the reactance coil E is now throu^ the
arc A^B, instead of through its mmcr
circuit. Gonsequently the arc ^'B is now
supplied with current, partly fnon thetTaB»>
former and partly from the reactance ooil XL
The new circuit from the traoaformar is
indicated by the arrows indosed in ciwkB>
The amount of reactance inserted in tlie
drcuit reduces the pulsations of the direel
current sufficiently for sXL ordinary com-
mercial purposes. Where it is advisable to still further reduoe the ai^ll-
tude of the pulsations, as. for instance, in telef^one work, Hob ia done with
very slight reduction in efficiency by means of reaetanoes.
0
F E
Fia.83. Rectifier Conneotk>ns
Shown Diagrammatioally.
WESTINQHOUSE MERCURY ARC RBGTIFIER OUTFITS. 481
!K13r«Hai70iB
OWJTMTS.
Thmam cratfita are a development of the conetant ouirent traiiflfoniict
adapted for uae with the mercury rectifier, receiviiig alternating current at
e conatant potential, and deliverinc a ooiwtant direct ooRent. By a special
. OQQQQQQOOQQ R OQQQ JSftQQPQ.,
ra
TTOnrowrnTragro-dM'
Fie. M and Fto. 0. Dlagrama of Weitinghoiise Mercury Arc Rectifler.
■nannment of coils the usual suetainins reactance is omitted, resultini
ID reduced floor apaoe and an improved eflidency. A boiler iron tank
nth cast iron cover, two alternating currents and two direct currents leads,
dssoibes the simple and rugged appearance of an outfit. (See Fig. 84.)
, Hie connections (Fig. 85) explain the operation. P-P and 8-S are respeo-
tave^ the primary and secondary; 8t the starting transformer. R the
netifier, ana A the auadliary coil for exciting the starting transformer.
,1
•
1
^^^
r-^
1
t
Fig. M.
The oatfit is eiafted by tipping the bulb, causing a spark between the
tcnninab of the starting transformer as the current path through the
mereory is intermpted. This breaks down the hi^ resistance of the nega-
tive deetrode and permits the establishment of the direct current.
The bulb is carried in a box which b easUy slid in or out between guides
to the bottom of the containing tank, thus making the buH> r^Iaeement a
Better of but a few moments.
Simple variable weights permit of adjusting the transformer so as to
Mver its exact rated direct current (Fig. 86), at aD ioads.
The power factor at f uD load averages over 70 per cent and the effidsncy
watt over 90 per cent for all sises of rectifier outfits. These are regularly
built in 25, 35. 50, 75 and 100 light capacities, either 25 or 00 cycles, for
KOO v.. oWoV.. 11,000 v., and lZ,2O0y. eirouits.
i
i
482
THE STATIC TRANSFORMEB.
MnRRRnr
^ili]ili!»lili!»l»
Fxo.87. Weettnghoose Meronry
Arc Rectifier for Battery
Ghargljig.
for which these outfits are built,
These outfits are intended to operal
frtun low constant potential eireuitsaa
deliver a oonstent D. C. voltage, varyiai
from 5 to 125 volts, aeoordins to deoiiu
Fig. 87 indicates a method of oonni^
tion which is essentially the same as k
the arc lighting outfits. SR ia a staria
reststanoe, for the rectifier; MN, the auB
transformer, BB* the D. C. terminals, sa
AA* the A. C. terminals. '
These outfits are started by tipping Ik
bulb. A spark due to interrupting
current in the starting resistance bi
down the hif^ necative electrode
anoe, permitting ^e direct current to I
established. In this outfit, like the ai
outfit, a special arrangement of ooils i>g
mits the omission of the usual sustains
coil. The D. C. volta^ is varied o
changes in the connection to the autt
tranaormer, or by changes in the A.(
impressed voltage msuie by an adjustao!
senes reactance. Control i>anels carryis
instruments, control dial, circuit breiucfl
etc., are furnished. Thirtjr amperes. 11
volts, is at present the maximum capacit
for either 25 or fiO cycle aervioe.
Althouffb the standard types of transformers of to-day are made on li»
found by long experience to be the best for all purposes, and are subject I
careful inspection and test at the factory in most oases, vet the variol
makers have such different ideas as to the value of the different polol
th:it in order to obtain fair bids on such appliances when purchased, it
always best to prepare specifications, and tne buyer should be prepared 1
conduct or check teste to determine whether the specifications have bei
fulfilled. Large stations should have a full outfit of apparatus for condog
iuK such tests ; but smaller purchasers can do quite well by having acom|l
tout superintendent, or by hiring an outside ei^neer to witness t£e tests i
tlie factoiy. It is not alwavs necessary to put each individual transfonm
! hrough all the teste, but the break-down test for Insulation should be m
I«< <>d to all.
Prof. Jackson gives the following requiremente for guarantiee of tnu
firmers.
IroM !•■• for 1000-voU transformers and for frequencies over 100 1
follows:
Capacity.
Iron Loss.
Exciting Current.
1000 w&tte ....
30 watte
1 jOEH ajDnAFMi.
L^watu
.tJOO watte
JiOO watte
^<I00 watte
u'.OO watte
r 500 watte
40 watte
60 watte
60 watte
80 watte
100 watte
150watte
.080 amperes.
.150 amperes.
.200 amperes. (
Fur frequencies less than 100 it may be advisable to allow 10 % higher lo
t-> avoid excessive cost.
KoTS. — Guaranties for iron loss should cover ageing for at least ot
-'war.
TRANSFORMER TESTING. 483
9 in •aoondary prewnre not to exceed 3 % between no load and full
CMd.
WUa9 •f <— iperaf rs after 10 hours' ran under full load. 70^ F.
Kb(mt«r'C.>.
KoTX,— TlUs meaenrement was probably meant bv Professor Jackson to
• made by thermometer. It is better to take the rise by resistance meas-
nment, in which case the allowable temperature is 60^ C.
vwrnwHv atraigtk of taMal»tl«a after full-load run, between
Mis and Detween primary coil and iron, at least 10 times the primary volt-
fe. Insulation resistance to be not less than 10 megohms, and guaranteed
lot to deteritwate with reasonable Berrioe.
NoTX. — See preTious matter as to test voltage.
SxdtlBir carrent for IOOO-toU transformers not to exceed yalues
ftnn in the above table, when the frequency is above 100. Tbe exciting
■Treat tacreoses as the frequencv decreaseSy and vuies inversely as the
eltsge. For intermediate capacities proportional values may be expected.
He further says : ** Tyant/ormers trhich do not meet the insulation and heat-
VffwtrantieM are untafe to Ji$e upon commercial electric liphting and motor
trcuitSy while tho$e tchtchdonot meet the iron loM^ regulation^ and exciting
^irrent guaranties waste the company's monty."
Tbe characteristics of a transformer, to be detennined by tests, are as
bllowB :
(1) Insulation strength between different parts.
(2) Gore loss and exoiting current.
(3) Besiataneea of primary and secondary and PS,
(4) Impedanee and copper loss, dlreot measurement.
(5) Heating and temperafeuve rise.
(S) Ratio M voltages.
(7) Regulation and effioieaoy, which may be calculated from the results
ti tests ($, (3), and (4), or may be determined directly by test.
(A Polarity.
Toe instruments required to make these tests should be selected for each
prticiilar case, and eoasiat of ammeters, voltmeters, and indicating watt-
seters.
For central station work, the following instruments will suffice for nearly
HD7 ease which may come up in <vdinary practice.
A. C. Voltmeter, reading to 150 volts, and with multiplier to say 2600 volts.
▲. G. Ammeter, reading to 160 amperes, with shunt multiplier if necessary
to carry the gresktest output.
indicating wattmeter, reading to 160 or 200 watts.
' NoTB.>- For full data and examples of transformer testing, see pamphlet
Ro. 8126, '* Transformer Testing for Central Station Managers." by Gen-
eral Electric Company, and Westinghouse Pamphlet No. 70».
Xiia«latl«B T««t.
This is the simplest and most Important test to be made, for the reason
ihat one of the principal functions of a transformer is its ability to thor-
oughly and effectually insulate the secondary circuit from the primary
drcuit.
Tests of the insulation of practically all high^potential apparatus are now
esrried out by high pressure, rather tnan by test of the Insulation resistance
^7 galvanometer. Some insulatlosis wiU show a very high test by galva-
•ometer, but will fall entirely under test with a voltage much exceeding that
at which it Is to be used. On the other hand, it is not uncommon to And
insulation such that, while the galvimometer tests show low resistance, it
vill not break down at all under the ordlnarv voltases. For this reason, it
a common practice among manuiFacturers of transformers to apply a rood-
^ratelj hi^ voltase, from two to three times the working voltage, for a
<bort period, usually about one minute.
_ The Committee on Standardisation of tlie A. I. E. E. has given certain
voltsges which they recommend to be used in the testing of anelectrical ap^
paratus, and the tables sad methods of application for the testing of trans-
lonners will be found in paragn^^hs Nos. 217 to 221, both inclusive in tae
434 the: static tbansfoeukb.
latMl rarltlon ol tbe rnlM at tliM ComnilHat vUsh vUl be foBBd ■!
In the book,
Xd ctukd&rd trftnifonaoim th«e« In^nLetlen taeU ihouid be (1) betweea prt-
xnarj uul un^ooA^rj, and batwoeu prlmuy imd corv »nd frftm* ; (3) tMtwMK
MOonduT uid core end ciue.
ToobTlaw uiT Indosed polentlalitrtln, (be iMonduT ilianld b« frcoDdel
wbUa ""fc'"g Iha teat between the prlmuj uid MiynidkiT, and betae^
priiiiktj uid core ud esM.
lu tcetlng between tbe prlnuur A>d Meondarr, or batmen the prtmaiT
and oore and fnuo*, the aooondaij moat ba oonnaotad to the oore ana
Itlial
aa Tall aa all aeooudary leada, ...
a nutform poUntlal itrftlu during uio «»•■
SiyiK. — Sittmtltx/0nparIciiie-gapimrvt,aiuliutiutBiut4t4t<tftm'tnrf
ditclUMTit.
Froni one point o( Ttar, the f aotor of aafel* o( tht aaoondarj need ihM be
peetar than (hat of (hs primarr, and If 10.000 Tolti laoonalderedaaanelest
teat for a MOO-Tolt primary, UOOTaita might b« inlBolent for aVO-n>llaee-
ondar J. But a (hln Mm of IninlmUou may aaall; irl(hi(and a teat of lOO
TOlta, although k la to weak maflhanl-
oallj aa to be daugetooa. A KM^Ttdt
aeocmdazy ihonld therefozv be taateJ
for at leaal KOO Tolti In order to goar-
antee it anlnat breakdown dve to
maohanioal veakneaa.
like dnradon of the Imnladon teat
maj T^T ■omewhat wl(fa the roagnl-
tode <a tbe ToKage spiled to Oe
tranaformar. If (ha (eat la a a«*ere
one, 1( abonld not be long eondnmdi
for while the intnladon niay niailllj
wllha(and (he momeotarr wlta»-
tloD of a Toltaga St« or ten Umae the
normal B(raln,'re( eoatinnad mpplit»-
don of tho Toltage naj Injare tAo tn>
ondarj ahould ba grounded. Id taal-
Ing between one wladlDg and the core. Ear uample, an Induoed notenUal
■train li obtained b«(weaD the sore and tha Mlmr winding whlsh may be
giDOb greater than tbe strain to whloh the Iniulatlon |j labjeoted imdar
Bar working eonditlong. and grealer (heratore (ban It la dealgned (r
d. In tMtlng betweao Che primary and the eore, tha Indacedpo-
etweea the lecondarT and tha core mat be HTenil (houaand Tolti,
peoondary mny thus be broken down by an Inanlatlon teat a^^Uad
H> inn prtmarr under oondlUouB which do not exist In tha natural uae of
(he iraiutoniier.
Attention te further called to the fao( (hat during the teat all prtmair
lead! as well as nit lecondary leads should be oonne^ed together. If only
nne terminal of Gha (ransformar winding Is oonneated (o the high potontial
(ranstoraier, tbe poteDtial strain to wblob It li subjected may raij throng^
Dut (he winding, and may ereu be Tory much grea(er a( aome point Iban at
the termlDala to wbleh tbe roltase Is mimliaa. Under saeh oondlUona the
reading of (he stado TolUne(eT affords no Indloatlon of the strain (o whMi
(he winding U lubjeeted.
Indications which are best learned by experienee rereal to tbo opermttv
the eharaatar of (he Inaalatlon under test. The tranafomar tn teat requlra
a charging corrent tarylug In magnitude wlUi Its sixe and dadn. Fran
iitomiar, tha oharglDE current mar be
oltage applied to the Insulation laloen
I tnsnlatlon under test be good there will be no dinonlty In
mtlal up to the dealred pniit by Tarylni Uw rhaottat. U tl
TRAJSBWOSMM& TXSTINQ.
486
ttoBbevwk or detoattTo, 11 will be lmpoMlbl« to obtain » blch Toltage
•eroH It, and an excetaiTe eharglng ourrent vlll bo Indloftted by the am-
laabUity to obtain the desired potential acroea the inanlatlon may be the
nielt merely of Urg« eleotioataae capacity of the insulation and the eonse-
qiMnt high charging current required, so that the high potential trans-
fonaer may not be large enoo^ to supply this current at the voltace
deiired. ^
A breakdown in the insulntion will result in a drop in Toltage indicated
by the electrostatic roltmeter, an ezoesslTe charging current, and the bum-
iag of tbe insulation if the discharge be oontinned for any length of time.
In tsking measurements of core loss and ezdting current, the instruments
zeosired are a wattmeter, Toltmeter. and anmieter.
One of the two f ollowins described methods for connecting up the instru-
Bsats ii uoally employed, although scTeral others might be shown. These
■wttiode differ only In tbe way of connecting up the instruments, and are as
fiBilovt:
Melh«4 1. — The Toltmeter and pressure coil of the wattmeter areoon-
neeted directly to the terminals of the test transformer. When the pressure
of the Toltmeter Is at the standard Toltage the reading of the wattmeter will
be the eore loss in watts. It is oTident from an inspection of diagram 89
tbstthe wattmeter will indicAte, in addition to tbe watts consumea by the
tait transformer, the /*i2 or copper loss in both the pressure coil of the
vsttaeter and Toltmeter. Hue error, howcTcr, being constant for any
INMiire, is easily oorrected. This method is Tery good for accurate results,
•adirtisre the quantities to be measured are smaliit is most desirable.
i
WITOII MAlCTAIieC
WATTMme TSaTTIMM
Fio. 89. CJore Loss (Method 1).
••—The current coils of the wattmeter are inserted between
stermlBalof tiietest transformer and the terminal of the Toltmeter and
prenve ooll of the wattmeter (see diagram 90). In this method the error
istiDdiKed Is the HM loss in tbe current coil of the Toltmeter. This is a
vwy mseh smaller error than in Method 1, but does not allow of an easy or
Mcwate correction, and the results obtained by it must, therefore, be' taiken
jnthoat eorreoticm. For this reason Method 2 is more couTenient, and for
wo aessurement of large core losses, and for commercial purposes, it is
"™«l«Btly sccurate.
VMNMLV
■aeitTANCt
TEST TRAM*
Flo. 90. Gore Loss (Method 2).
Ooie kasM and exciting current should be measured from the low-poten-
wiUe of the transformer to SToid the introduction of high Toltage In Uie
teit.
vmA Kxdtailoa Cvrremt.
hi «a ordinary commercial transformer, a glTcn core loss at 00 cycles may
JJ>>itt of 70 per eent hysteresis and 80 per cent eddy current loss, while at
»«yelei the same transfomer may bays 06 per cent hysteresis loss and 16
iVfSBt sddy cnrrsDt loss.
486 THB STATIC TBANSFOBBIBR.
Tho oore Ion is also dependent npon the wave form of the impressed
£.M.F.y a peaked ware giving somewhat lower core loeses than a flat irm^e.
It is not uncommon to find alternators havlns such a peaked ware form
that the core loss obtained, if the transformer Is tested with current f^rom
them, will be 6 per cent to 10 per cent less than that obtained if the trauM*
former is tested from a generator giyin^ a slue wave. On the other hAnd,
generators are sometimes obtained which hare a rerv flat wave form, «>
that the core loss obtained will be greater than that oStained from the use
of a sine wave. •
The magnitude of the oore loss depends also upon the temperature of the
iron. Bota the hysteresis and eddy current losses decrease slightly as Um
temperature of the iron increases. It is well known that if the tempersr-
ture be increased saflldently, th^ hysteresis loSS disappears almost entirelr,
and since the resistance of iron increases with the temperature the eddy
current losses necessarily decrease. In commercial transformers, an is-
crease in temperature of 40^^ G. will cause a decrease in core loss of f roai 6
per cent to 10 per cent. An accurate statement of core loss thus nnrowi
tates that the temperature and wave form be speclfled.
If, in the measurement of core loss, the product of impressed Tolts and
excitaUon current exceeds twice the measured watts, tnere is jreasoa to
suspect poorly oonstructed magnetic Joints or higher iron densitieB than are
allowabm in a well-designed transformer.
meaattremeni of Realetaacti.
Resistance of the colls can be measured by either the Wheatstone Bridge
or Fall of Potential Method.
For resistances below one or two ohms it is generally more accurate to nsa
the Fall of Potential Method.
Besistauces should always be corrected for temperature, common prae-
tice being to correct to 2fP centigrade. For pure soft-drawn copper this cor-
rection is .4 % per degree centigrade. Beadings should be taken at several
different current values, and the average value of all the readings will be
the one to use. (See Index for correction for rise of temperature.)
Having obtained the resistance of the primary and secondary coils, the
PB of both primary and secondary can be calculated ; the sum of the two
being (very nearly) equal to the copper loss of the transformer. If it is
preferred to measure the copper loss directly by wattmeter, then we most
make test No. 4.
The fall of potential method is subject to the following sources of error :
(1) With the connections as ordinarily made the ammeter reading Includes
the current in the voltmeter, and in order to prevent appreelable error the
resistance of the voltmeter must be much greater than that of the reeiscanee
to be measured. If the resistance of the voltmeter be 1000 times greater, an
error of ^ of 1 per cent will be introduced, while a voltmeter resutanoe 100
times the coil's resistance will mean the introduction of an error of 1 per
cent. Correction of the ammeter reading obtained in (3) may thus become
necessary, but whether or not it be essential will depend upoii the accuracy
desired. (See example below.)
(2) The resistance of the voltmeter leads must not be sufficient to aifect
the reading of the voltmeter. .
(3) Since the resistance of copper changes rapidly with the temperature,
the current used in the measurement should oe small compared with the
carrying capacitv of the resistance, in order that the temperature may not
change appreciably d urine the test. If a large current is necessary, read-
ings must be taken quickly in order to obtain satisfactory results. If a
{gradual increase in drop across the resistance can be detected within the
ength of time taken for the test, it is evident that the current flowing
through the resistance is heating it rapidly, and is too large to enable accu-
rate measurement of resistance to be secured.
It is quite possible to U8e a current of sufficient strength to heat the winti*
ing so rapidly as to cause it to reach a constant hot resistance before the
measurement is taken, thus introducing a large error in the resyulta. Great
care should be taken, therefore, in measuring resistance to avoid the nse of
more current than the resistance will carry without appreciable heating.
(4) Considerable care is necessary to determine the temperature or the
whiding of the transformer. A thermometer placed on the outside of the
winding indicates only the temperature of the exterior. The transformer
TRAKSrOBMSB TB8TINO.
487
; 111001(1 be kept in a room of oonitant temperatore for many hoars in order
Ithat the windlngB may reach a oiiiform temperature throughout. The
; rarfaee temperature may then be taken u indicative of tliat of the interior.
JiHipedmnce mmA Copper-MiOee Test.
MeikodI 1. — In this method, which was first described by J>r. Sumpner,
the secondary coU is short-circuited through an ammeter. 4- wattmeter
and a voltmeter are connected up in the primary circuit in a manner similar
to either of the two methods described for the core-loss test. An adjustable
resistamee or other means for varying the impressed voltage is placed in
series with the primary circuit.
To make the test, the voltage is raised gradually until the amineter shows
that normal fall-load current is flowi^ through the secondary circuit.
Besdlngs are then taken on the wattmeter and voltmeter.
This method of measuring the impedance and ooppw loss of a transformer
is now seldom used, on account of the llabilitv to error due to the insertion
of the ammeter in the secondary. In addition to being Inaoeuratei it usu-
tlly requires an ammeter capable of measuring a very heavy current.
HetkWI 9, — This method differs from Method 1 only in that the seo-
ondsry Is short-circuited directly on Itself, an ammeter being inserted in the
primary circait. The diagram of connections Is shown in Fig. 9L In con-
neeting up the voltmeter and the potential coil of the wattmeter, the same
eonecBonB hold as in the measurement of core loss and exciting current,
and e<mnoction8 nuMie according to whether accuracy of results or slmpUolty
of test is the more imporant.
WATTMnSR
Fio. 91. Impedance Test with Wattmeter.
HsTing the readings of amperes, volts, and watts, we obtain from the
tnttwo the Impedance of the tranaformer. Thl8 Impedance Is the geo-
metrical sum of the resistance and reactance, and is expressed algebraically
ss foIlowB :
«=Vi?« + (2»mX)«»
vbere s = Impedance,
R=: Resistance,
L = Coefficient of self-induction,
/= Current in amperes,
a = Frequency In cycles i>er second,
3r a Z = reactance of the circuit.
In a test on a transformer with secondary short-circuited as In Fig. 91
tVjTe,and primary connected to 2000 volts, the impedance volts were 97 at
fuU-losd primary current of 2.5 amperes, then
Impedance = r-^ = 38.8 ohms,
ud
97 X 100
Impedance drop = -«qqq- = *-8B per cent.
The reading on the wattmeter Indicates the combined PR of the prlmarr
uid secondary coils, and lu addition includes a very small core loss, which
can be neglected, and an eddy current loss In the conductors.
In standard lighting transformers, the impedance voltage varies from
Spsr cent to 8 per cent. In making this test, careful reoord of the fre-
qoency should be made, as the impedance voltage will vary very nearly
vith toe frequency.
488
THB STATIC TRANSFORMER.
j^WWA^t^^ "^'"^
! -MlMARY
TO TNNEeH»HASC
ALTERNATOR 8
j PMHARy
I TRAmPORMER MX S
Q
ALTERNATOR
Fio.92.
PRIMARY
•EOONDARV
■W/J/V^ j^WWi/^ fMWAi
->/WW\r-M/WV\r' WWWV-*
rVWWS
PRIMARy
MCONOAFjr
.B'
.B'
■l-vsv-f
U/yJUsyJ
^11*^11^*11^ r^'T'^r^
TO THREE-PHAaC ALTERNATOR B
TO THREE-PHAae
ALTERNATOR A
Fxo. 03.
Figures 02 «nd 93 show a method of loading three-phaae traDRfbrmfln
for heat test.
TBANSFOBMER TXSTING.
4S9
To tati the traasfonner for its temperatiire liMt it la neoesMurj to run it
it fall excitation and full-load correut for a certain length of time. An
(Mgh^honr run at foil load will usaally raise the temperatare to its highest
iefakt, and in the case of lighting transformers a full-load run very seldom
jKAtinaes longer than eight hours in practice. If it is desired to find Just
||Ast is the final temperature rise under full load (as is often the case with
tnoslormers for power work) the transformer can be operated for two or
ttres hoars at an overload of about 26 %, after which the load should be
^Mdaeed to normal, and the run continued as long as may be necessary.
: There are sereral methods for making heat runs of transformeri, and all
of them aiwrozimate the condition of the transformer in actual serrice.
Hemt Vewt, Heth«dl 1.— The primary is connected to a circuit of
ifbe proper Toltage and frequencj. and the secondary loaded with lamps or
^reabtance until fall-load current Is obtained. The temperature of all acces-
libls parts shoald be obtained by thermometer, and the temperature rise
of the coils determined by increase of resistance. Frequent readings should
bs taken during the run to see to what extent the transformer is heating.
Hettt T^wt, ]H«th«4 9. — Where the transformer is of large siae, or
soflcient load is not obtainable, the motor generator method of heat test is
preferable. Two transformers of the same Toltage, capacity and frequency
are reqi^red, and are connected up as shown in ^g. M.
vokTAOi TO M Arraox. Twiec thi
VOLTAQC OP KAON TIUMroiniU,
.IT MUST M AOMOTCD OMTIt. nJU. LOAD
m.'
Noorti
TNM VOkTAM T9 It THAT Of Jtm,
WOONOARY OP lAON
FlO. 94.
The two secondaries are connected in parallel, and excited from circuit
A at the proper voltage and frequency. The two primaries are connected
In Mries m such a way as to oppose each other.
Theresaltant voltage at B will be aero, however, because the voltage of
the two primaries Is equal and opposite. Any voltage impressed at Bwill
tbv cause a current to flow independent of the exciting voltages at the
tnuformer terminals, and approximately twice the impedance voltage of
one transformer will cause full-load current to flow through the primaries
and teeondariee of both transformers.
The total energy thus required to run two transformers at full load is
nsrely the losses ui the iron and copper. Circuit A supplies the exciting
earreat and core losaes, and circuit B the full-load current and copper
Heat Tmmt, Metb^d 3. —When only one transformer is to be tested,
and this transformer is of large capacity, a modification of the motor gen-
erator method can be used as described below :
This method was first used in testing an 890 k.w. 25-eycle transformer made
for the Carbomndum Company of Niagara Falls. The connections are
■bown In Fig. 9&. ^ _,
Both primary and secondary windings are divided into two parts, the pn-
nvy coils x and y being connected in multiple to the dynamo circuit, but
tt auxiliary transformer capable of aAding a few per cent E.M.P. to that
knlf of the primary is connected as shown in the y naif.
490
THE STATIC TRANSFORMER.
By this means the primary colli are properly magnetised, anA
currente oan be passed through them by varying the auxiliary £.Mr»J?
The two halves of the secondary coils are connected in series In.
tlon to each other, and are subject to an auxiliary E.M.F. from tb^
!;enerator, but reduced to the proper voltage by the auxiliary
ormer B.
The currents were measured in all three transformer circuitSi
E.M.F. of one-half the secondarv was measured.
The method is accurate enougn for large units, and is quite handy "vJ
no large dynamo can be gotten for supplying full-load current«, a« in CI
ease current is required only for the transformer losses and for suftj
the auxiliary transformers.
PftlMART
Fio. 96. General Electric Method of Testing One
Large Transformer.
Fig. 96 shows connections for heat-nin on three single-phase
formers, or one three-phase transformer. The primaries and secondaii«s
are oonneoted in delta, and in one oomer of the primary impedance toI-
TOALTERNATOft
SUPPLVINQ
TOTHmS'MMai
ALTERNATOR SUPPLVIMQ
CORE
PMMAfty
FiQ. 96.
tage for the three transformers connected in series is impressed. Tlie
current circulates in the delta connections and is entirely independent of the
secondary voltage. The method outlined above requires only power enou^
to supply the losses.
TRANSFOBMER TESTING.
491
TeMijperatvre Rise.
To asoertain the temperature rise of the differeut parte of a transfonner,
tbliermometers areplaced on the Tarious parte, antf readings taken at fre-
quent interrals. Tlieae readings, however, Indicate only the surface teoi'-
peraAvire of a body and not the actual internal temperature.
Xl]ke areraffe rise of temperature of the windings can he more accurately
determined bv means of the increase of resistance of the conductor, and
is «leteniiliied[ by knowing the resistances hot and cold.
Let Rt =r resistance of one coU, cold. .
Bk = resistance of one coll, hot.
Tt = temperature of one coil in cent, degrees, cold.
Th = temperature of one coil in cent, degrees, hot.
K ^ temperature of coefficient of copper .00#,
r* =
This equation is based on the assumption that the resistance of pare cop-
per increases .4% of its yalue at zero for every degree centigrade rise in
temperature.
If it be desired to know the temperature rise^f both primary and Second-
ary ooils, their hot and cold resistances must be determined separately ; but
it 18 eostomary to determine the temperature rise by resistance of only one
eoiL, osoally the primary, and comparing the secondary temperatures by the
thermometer measurements. The method for taking these measurements
is described in the paragraph in this section on measurement of resistance.
Am a cheek aoainst possible mistakes in winding the ootls and connecting-
op. a test ■hoold be made for ratio of Toltages.
The ratio test is made at a fractional part of the full voltage at no-load
enrroit, and sbonld not be substituted for a regulation test. An error of one
or two per cent is aaite admissible in making this test, beoaose of its being
tslwB at partial voltages.
Reirnlatloa.
The regulation of a transformer can be determined either by direct meas-
nrefment or by ealcolation from the measurements of resistance and reac-
taaee in the transformer. Since the regulation of any commercial trans-
former is at the most but a few per cent of the impressed voltage, and as
errors of observation are very liable to be f uUv one per cent, the direct
method of measuring regulatfon is not at all reliable. ,
Ses«latloa by Direct IHCeaevremieMte.
Connect np the transformer with a fully loaded secondary, as in Fig. 97.
If the primarv voltage is very steady, voltmeter No. 2 only will be neces-
sary, but it is better to use one on the primary circuit also as shown. A
TOW
TW^
UMPUMD
rm
3i U
!
Fio. 97. Test for Regulation of Transformer.
Teading of roltmeter No. 2 is taken with no load, and again with load, the
difference In the two readings being the drop in voltage on the secondary.
We. therefore, have,
% Regulation - 100 - (100 X Reading at full loadx
-K mnpuawuu .v« y Reading at no load /
492
THE STATIC TRANSFORMER.
Several metho<ls of oalealating the regulation of transformers from tbt
measurements of resistance and reactive drop bare been deylsed.
Below is a method of Mr. A. B. Erereet, which hss been found to answer
the requirements of daily use.
Let IR — Total resistance drop in transformer expressed ss per e«&t of
rated voltage.
/JT -i Beaotire drop, similarly expressed.
P — Proportion of energy current in load or power factor of load. Wat
non-inductive load P « 1.
W " Wattless factor of primary current.
(With non-inductive load, W — Magnetising current expressed as
a fraction of full-load current. With inductive Ipad, W « Watt*
less component of load, plus magnetising cnrrento
Tien if volts at secondary terminals — 100%,
Primary voltage —
JT- V(ioo + PIB + fnx^+ (/Jr)«.
Wot ladvottve liOadi
jr - V (100 + PIR + WIX)* + (PIX - WIR^,
In each of these equations the last expression within parenthi
sents the drop " in quadrature.'*
The magnetising current — y (Exciting current j — (v itMf) *
For frequencies of 60 cycles or higher, magnetising current may be taken
as 76 per cent of the exciting current.
Extracting the square root in the expression for regulation may be
I of the following table :
avoided in the use
Quadrature Drop.
Increase In Primary Yoltage.
%Ji per cent.
8 " ••
8J5 " "
.026
.04
.06
II
cent.
II
II
4
4JS
It
t(
It
II
.06
.10
II
II
It
II
6
0.6
«•
It
II
It
.13
.16
II
ti
II
It
6
t(
««
41
l«
.18
.21
it
It
u
II
7
7JS
tt
II
<l
.24
.27
It
II
It
II
8
Ii
II
.31
II
It
II
II
9
9.6
l«
*l
II
.30
.46
II
It
II
II
10
1*
II
M
It
II
I
I EFFIGIENCT. 493
Aj an example, take a 2 k.ir. transfonner haTing the following losses :
/Jtdrop-«2%.
/JT drop -• 3J(%.
Bxeitiiig eurrent — 4% or JtH; then magnetising current — 75% of this,
or in.
1. Wmm'WmMmetirm I<«ad.— 8eeoudarTToUage» 100%.
Primary roltage in phase - 100 + 2% + (.08 X sif) - 102.1%.
Qnadratnre drop — 8.5% ; this from table adds .00% of total primary Tolt-
■ge — 108.16%.
A IS
The drop ia 2.16% of secondary roltage, or ' ^- «• 8.11% of primary rolt-
age, which is tbe tme regulation drop.
•• W^Jmsitlte JLoad. — With a power faelor of .88, wattless factor of
load « A, and adding magnetising current (which in most cases mighf'be
neglected on Indnctire load), W becomes JS2.
The prinaary voltage in phase is now 100% + (2% X ^) + (3.5 X ^2)
«103^%.
The quadratniw drop is (.SOX 3.5%) - (.52 X2%) - 1.97.
From the table 1.97% adds .02% to primary yoltage or
108.54 + .02%- lOaJMw
Primary Toltstge « 103.56
Repdation drop — loajifl'* ^*^% ^' primary voHageb Regulation drop
ihoald always be eacpressed finally in terms of primary roltage.
The aboTe-deseribed methods of transformer testing are in use by one of
the lam mannfartturers, and present average American shop practice.
The loUo wing matter is laigely from the important paper by Mr. Ford
and prssents the eommonast theoretical test methods.
The elHoleiney of a transformer is the ratio of its net power output to Its
BOSS power Input, the output being measured with non-lnductlve load.
The power Input includes the output together with the losses which •re as
foOows:
(1) The core loss, which is determined by test at the rated frequency and
^IThe i* B loss of the primary and the secondary calculated from their
riiiiiitsnfiTe
Saaasple.
Transformer, ^pe H, 00 Cycles, 5 k.w., 1009-3000 Yolts Prim., 109-209
Tolls Sec.
AVPE&BS.
Primary, at 2000 Tolts 2.5
Secondary, at 200 Tolts 25
BssiSTAKCK. Ohms at QKP O.
Primary 10.1
Secondary 0.087
AtPnIlLoad. _
LoBSxa. Watts.
Frimaryi*ie 83
Secondary i* J2 48
Total PB 106
Core Loss 70
Tbtal Loss 176
Output at Full Load 6000
Input *• " " 5176
Efficiency 6000/5176 or 98.6%
494 THE STATIC TRANSFORMER.
At Half Load.
Losses. Watts.
Total i* 22 26
Gore Lobs 70
Total Lobs 96
Output 2600
Input 2G96
Bffiolenoy 2600/2S96 or 96^
The all-day effloieney of a transformer is the ratio of the output to tbm
input during 21 hours. The usual conditions of practice will be met if ths
ealculationTs based on 5 hours at full load, and 19 hours at no load.
Output. Watt Hbs.
5 Hours at Full Load 26O0O
19 Hours at No Load 0
Total, 24 Hours 26000
Im*TTT
5 Hours at Full Load 25875
19 Hours at No Load (Neglecting PB Loss due
to Excitation Current) 1330
Total, 24 Hours 27206
AU-day Efficiency 26000/27206 or 91.9%
In calculating the efSciencies in both of the abore examples, the copper
loss due to ezoilation current of the transformer has been neglected. Tlib
current, in the example given above, is less than 3%, and its eflfeet on the
loss of the transformer is thus negligible. Even at no load the total P R
IjM introduced by it is less than one watt. It is quite necessary, howev^
that the loss introduced by the excitation current should be checked in all
oases. In some transformers, for example, the excitation current may
reach 30% of the full-load current, and thus its effect is noticeable at large
loads, while at \ load the loss in the primary winding due to exoitatioiB
current is greater than the loss due to tne load current.
Inasmuch as the losses in the transformer are affected by the tempera-
ture and the wave form of the £Jtf.F., the efficiency can be accurately
speciHed onlv by reference to some definite temperature, such as 25° C, sjia
by stating wnether the E.M.F. is sine or otherwise.
The foregoing method of calculating the efficiency neglects what are
known as *Qoad losses," i.e., the eddy current losses in the iron and the
conductors caused by the current in the transformer windings. The watts
measured in the impedance test include ** load losses " and /* ^ losses to-
gether with a small core loss. Considerimj; the core loss as n^Iigible, the
** load losses " are obtained by subtracting from the measured watte the P£
loss calculated from the resistance of the transformer. It is sometimes
assumed that the " load losses " in a transformer when it is working under
full-load conditions are the same as those obtained with short-circuited
secondary, and it is stated that these losses should enter into the calcula-
tion of efficiency. Many tests have been made to determine whether or not
the above assumption is correct, and while the results cannot be considered
as conclusive, they indicate in every case that, under full-load conditions,
the " load losses " are considerably less than those measured with short-
circuited secondary. Inasmuch as these losses, in general, form a small
percentage of the total loss in a transformer, and in view of the difficulty
in determining them with accuracy, they may be neglected in the calculs-
tion of efficiency for commercial purposes. The measurement of watts in
the impedance test is, however, useful as a check on excessive eddy current
losses m a poorly designed transformer.
DATA TO BE DETERMINED BY TESTS. 495
SnFhmiformera ar« generally deslsned so that the InstantaneoTU direotion
lov of the current in certain selected leads is the same In all tranaform-
of the same type. For example * referring to Fiff. 98, the transformer
there shown Is designed so that uie current at any in-
j^ B Btant flows into the primary at A, and out of the sec-
II I A ondary at C. Some such system is necessary, in order
I 9tm0K9 I y tliat transformers may run In parallel when similar prfc
* "^ mary and secondary leads on different transformers are
connected together. The test which is made to determine
whether a given transformer is identical in this respect
-with other transformers of the same type is known as
the polarity test.
The polarity test should be unnecessary when banking
transformers of the same type and design. When, how-
eTcr, transformers manufactured by different companies
are to be run In parallel, it is necessary to test them in
order to avoid the possibility of connecting them in
such a way as to snort circuit the one on the other.
Their polarity may be determined by one of the follow-
ing methods.
In Fig. 98 primary lead A should be of the same po-
aritj as the secondary lead C. Connect the primary lead B to the second-
ary I«ad C. Apply 100 volts, say, to the primary AB of the transformer.
The voltage measured from A to D should be greater than the applied volt-
age If the traneformer is of the correct polarity. In other wordis, a trans-
fofiaer connected as shown should act as a booster to the voltage. If the
l«adi A andD are not of the same polarity, the voltage measured from A to
C iboold he less tban that applied at AB.
If a standard transformer, known to have correct polarity and the same
ratio SI the test transformer, is available, the simplest method for testing
the polarity is to connect the primaries and secondaries of the transformer
in parallel, placins a f uae in series with the secondaries. On applying volt-
sge to the primanes of the transformers, If they are of the same polarity
and ratio, no current should flow in the secondary circuit, and the fuse will
remain intact. If the transformers are of opposite polarity, the connection
vill short circuit the one transformer on tne other, and the fuse selected
ihoald therefore be small enough to blow before the transformers are
ininred.
In nearly all tranaforraers there will be a slight current in the secondaries
when connected as above. This current is known as the exchange current,
ad shoold be leas than 1% of the normal full-load current of the trans-
nmaer.
DAVA VO BS DETKIUHLKIIKXK SIT TBAU.
Partly from a paper by Arthur HiUyer Ford. B. S.
!• Copper loss-, to determine the efficiency.
IL Iron-core loss, hot and cold, to determine the efficiency : to separate
.. tlM hysteresis from the foucault current loss,
u Fr= watts output,
/=: watts iron-core loss,
... C= watts copper loss,
USD us
KffletoC7 = 100 - {TrTT+C >< "")
Foucault currento loss should decrease with an increase in tempera-
ture.
HyBteresis loss ia supposed to be constant regardless of heat.
^> Open circuit or ezoitmg current.
I*,' regulation, to determine the masnetic leakage.
V > Bise in temperature In case ana out of case, for no load and full
_, , load ; with and without oil.
vl. Insolation.
THE STATIC TRA.NSFOBHBS.
li npMlallT Tklukbla irhera ths {ruufonaen to b« tMt«d are of lu
paoItT, uidKaoariwof pow«ri[re»tei>ouIi to put them auder tnll km
the ordlnuT «■; Is nnBTallablfl. A Bapply of cnirent at an UDODnt •
Tlut grular than tha total Iimbm of both iraiufonDen li all that li n
larj. f ollaving la a diagram of the conDeotlDns, bj vhloh It will be
(hat the tmufonnen an M> oonneoted that one teedi the othoi, or
Toik In oppoalUan.
F >r ATTton
Tnuwformer*.
tn mtklng tbs (eat, cnmnt !■ tarned on and the ralslauce R adjwti
nntll fnll-Iiwd carrant flom In the aecondiry, u thown bj the anuneiari
tbe vatta r«ad on W are eqoal to tSe Iron loeaoi In both tnuuformsi*! u
W, the loaiee In the oopper of the tranafonnan ploi the eiqiper km IB tt
laiidi and in the oairant sotla at W, and A.
The total Ioh In both tnnstoimen 1« mtta losa - W + W.-'^.vhen
la the loM In the IsadJ and Inatriuaents wbieh ma; ba ealeDfated'tn> PR.
MXIWMl vr Dr. >aB>Ki>(>r. ■»■ I.m» - The f olIowlnsJUnM
Vi.. ihowi the oauneotloni fur Hi. Bmapner'* tatt for iron lone*. 3ha low
Fio. 100. Dr. Smnpuer'a Taat tor Iron
DATA TO BE DETBRMIKED BY TESTS.
497
^
imwiiiw Bide im eonneot«d to a Boarce of current of the same praMure at
vUeh tlM transformer Is expeoted to work, thus prodacin^^ the same pri-
-Marr Toltace in the high-presanre fide at which it is expeoted to work.
WItA the primary eiroult open, the iron losses in the tvaosiormer are read
tfreetly in watts on the wattmeter.
Copper MiSaa. — The next diagram shows the oonneetions for determin-
ing the eopper losses. The low-pressure side is short-elrouited through an
ammeter, the high-pressure side being connected to the 100>volt supply-
mains. The resistance B Is then adjured to obtain full-load or any other
derired current in the secondary, as shown by the amjneter. The reading
of the wattmeter will then show the total copper losses in the transformer
sad in the ammeter plus a rery small and entirely negligible iron loss. The
ammeter losses and that in the leads may be calculated i>y PR. The small
iron loss can be separated or determined by disconnecting the aouneter and
JUC
^-X/^^Mn^
n.
Fio. 101. Dr. Sumpner** Test for Oopper Losses.
adjusting B until the pressure on the primary is the tame as in the oopper
mil test; the wattmeter will then show the small iron loss.
The Iron loss is proportional to (R^-* and (gthe magnetic density is pro-
portional to the pressure at the terminals of the transformer, therefore the
iron loss is equal to K.(5^^'* where JT is a constant and (K the Toltage. In the
inm-loss test the (J^ — 1000 and in the oopper loss test
(B-100.
X X 1000>« - 63,000 K
KXIW"* - 1,600 i: - 2.5% of total iron loss.
Heatlmr.— Tests should be made at no load, at full load, and at inter-
mediate loads for rise of temperature of the transformers out of their cases,
ia their cases, without oil and with oil, if full data is wanted. If a strictly
eommerclal test is all that is necessary, a test with the transformer at full
load and set up in the condition it is to be run, will be sufficient.
Sorfaoe temperatures can be taken by thermometers laid on and covered
vith cotton waste. In oil-insulated transformers, the temperature of the
oil should be taken in two plaoes, — inside the coil, and between the coil
and case.
I«akmg« Di«p. — The drop in the secondary due to magnetic leakage
ean be found by deouctlng from the measured total drop in the PB drop due
to the resistaaoe of the ooll.
498
THE STATIC TRANSFORMEB.
•IPKCUPIOATIOIVA FOlt VJftAMSf OIUUBR9.
It is almost impoarible to enumerate the features to be induded in
fieatioos oovering transformers, because of the wide range of operation' and
service to which they may be put, necessitating different charaeteristies
for the transformers intended for different kinds of services.
For transformers operating from a fairly expensive source of supply, the
leading manufacturers have decided on characteristics which, in genflnL
will be covered in the. following tabulation.
This gives average characteristics of transformers designed for operation
on 60-«yole oiro\iits, and the figures given are based on operation of 2000
volts and sine wave alternator.
Capacity.
Core Loss
Watts.
Copper Loss
Watts.
Exciting Cur-
rent%.
Regulation %
1
85
30
9.0
2.8
2
45
50
7.0
2.5
3
55
70
3.0
2.3
6
70
105
2.5
2.2
7.5
100
150
2.3
2.2
10
120
180
2.3
2.0
15
155
275
2.2
1.8
20
185
300
1.5
1.7
30
235
475
1.2
1.5
50
335
675
1.0
1.3
Guarantees against serious ageing of iron should oover a period of at least
one year.
MSB OF TEm>ClKAT17IKS«
The rise of temperature should be referred to the standard oondltioos
of a room-temperature of 26° C, a barometric pressure of 760 nun. and.
normal conditions of ventilation: that is, the apparatus under test should
neither be exposed to draught nor inclosed, except where expressly specified.
If the room temperature during the test differs from 25" C. the observed
rise of temperature should be corrected bv ^ per cent for each" C. Thos
with a room temperature of 35" C. the observed rise of temperature hss
to be decreased by 6 per cent, and with a room temperature of 15" C. the
observed rise of temperature must be increased by 5 per cent. The tbsr-
mometer indicating toe room temperature should be screened from thermal
radiation emitted oy heated bodies, or from draughts of air. When it is
impracticable to secure normal conditions of ventilation <»i aooount of
adjacent engine or other sources of heat, the thermometer for measuring
the air temperature should be placed so as fairly to indicate the tMnpera-
ture which the machine would have if it were idle, in order that the rise
of temperature determined shall be that caused by the operation of the
machine.
The temperature should be measured after a run of sufficient duration to
reach practical constancy. This is usually from six to eighteen hours
according to the sise and construction of the apparatus. It is permissibls,
however, to shorten the time of the test by running a lesser time on an
overload in current and voltage, then reducing the load to normal, and
maintaining it thus until the temperature has become constant.
In eleotncal conductors, the rise of temperature should be determined
LOCATION OF TRANSFORMERS. 499
by the inereaae of their resist«nce where practicable. For this purooee
the reeiitenct miKy be meatured either by gaivanomater tebt, or vy drop
of potential method. A temperature ooefiicient of 0.42 per cent per degree
C tram and at 0° C. may be awnimed for ooppw . by the formula:
i;»-i2o(l+a00420aad JBi + 0 - i2o[l - 0.0042 (< -f 0)]
where Rt -> the initial reaistanoe at room temperature f C.
r« + 0 — the final xeeiatanee at temperature elevation 0° C.
R9 « the inferred reeiatance at 0° C.
These combine into the formtila:
0- (238.1 +.)(?:^±|^)'C.
For iaeiilation teet aee report of Committee on Standardisation of
ALE.E.. page 514.
I.OCATIOIV or TllAlffll^lftlUBlM.
1. Where practicable, the traDsformere should be placed in a boiler
iroo eaae, capable of withstaodinc an internal pressure of 50 lbs. per
■qfare inch, the case to be suitably vented.
1 Where a sheet iron construction is necessary, the case should be
made practically air tight and provided with a very large safety valve,
•0 that an internal exploeion cannot burst the case.
3. Provision should be made for rapidly drawing o£F the oil in case it
becomes necessary to do so.
4. Individual transformer units, or groups of units, should be located
in fireproof compartments, such compartments to be suitably drained so
tbat in case the oil escapes from the cases, it can flow out where it can do
00 harm.
5. Adequate means should be provided for extinguishing fire, and the
station attendants should be trained to know what to do in case of emer-
gency.
An oil should be selected which has a flash point not lower than, say,
175** C. Such an oil, if properly made, will have practically no evapora-
tion whatever at 100^ C, this temperature being higher than will be found
exeept under the most extreme conditions of temporarv overload.
Too high a flash test oil is undesirable on account of the viscosity being
■D great that the power to carry heat from the transformer to the cooler
ciw is greatly reduced, and on account of it being very unpleasant to
handle
Where rubber-covered leads are used, the rubber should be heavy (not
MSB than 1' wall per 10,000 volts) and of high quality, and a fireproof
covering should be used. Extra flexible cable is usually preferable. Rub-
bar may be tested for dielectric strength, insulation resistance, etc., but its
<iaalification for important uses is best judged by its mechanical proper-
to. To examine these, remove the braid from the wire for several inches,
rat without cutting the rubber except at the ends of the space. Here it
mould be cut (at both ends) down to the wire. It will be found in many
makes that there are two iomts in the rubber running parallel to the wire.
A bngitudkial cut alon^^ the wire, and down to it, should be made midway
between the joints. This will make it possible to easily remove the rubber
from the wire. First, test each of the joints by bending them over back-
*>n»- The best joints will sliow some tendency to open, and for this
"Cflson a double layer of rubber, with joints staggered, is desirable. In
^BBoy (so called) first class wires it will be found that the joints are just
wchtly stuck together, or break open on the slightest provocation. Such
^"uation is worthless. The quality of the rubber may be judged by cut-
tmg long stripe, about ^ wide, or less, and bending it double and as short
^possible. It should show no signs of cracking. Pure rubber is very
wti^nuKi strong, and it loses these properties in proportion as it isadul-
I
500 THE STATIC TRAN8FOBMEE.
•PBOKHOATlOirA 9^11 TMAItmWO
(G. E. Skinner.)
In the foUowing vill be found a brief spedfiention for & transfonner oil.
(1) The oil should be, a pure mineral oil obtained by Iraotional distil-
lation of petroleum unmixed with any other eubstanees and without sob-
, eequeat cnemieal treatment.
(2) The flash teet of the oil should not be lees than ISO*" O. (36«* F.),
and the burning test should not be less than 200^ C. (302* F.).
(3) The oil must not contain moisture, add, alkali, or sulphur
pounds.
(4) The oil should not show an evaporation of more than 0.2%
heated at 100<* C. for eight hours.
(5) It is desirable that the oil be as fluid as possible and thai the color
be as light as can be obtained in an untreated oil.
The method of making tests to determine the aboTS qualities should be
distinctly spedfied so that there can be no misunderstanding on aocount
of results being obtained by di£Ferent methods of test.
The spedfication for flash test giTsn above is intended to be low eoomh
so that there will be some leeway to allow for slight variations in the oil
and for variations obtained by different observers. It is expeeted thaft an
oil to fulfill this speoifieationwiU run soaathing higher than 180* flMh test
STANDARDIZATION BULBS OF THE AMBBI-
CAN INSTITUTE OF ELECTRICAL
ENGINEERS.
(JfowNd to JtcfM 7lh, 1907. A pproved hy ths BoaM of Diredcrt, Jun€ 21. 1907.)
DBFiifiTiONS Airo Tbchnical Data.
A. Definitions — Currents.
B. Definitions — Rotating Machines. '
C. Definitions — Stationary Induction Apparatus. i
D. General Classification of Apparatus.
B. HotocB — Speed CUssificanon.
F. Definition and Explanation of Terms.
Load Factor.
Non-Induotive and Inductive Load.
Power Factor and Reactive Factor.
Saturation Factor.
Variation and Pulsation.
IL PBBPOmCAMGB SPBOIVIGATlOlfa AMD TeSN.
A. Rating.
B. Wave Shape.
C. Efficiency.
Definitions.
Detennination of Efficiency.
[III) Measurement of Losses.
[IV) Efficiency of Different Types of Apparatus.
Direct-Current Oommutating Machines.
Alternating-Current Oommutating Machines.
Synchronous Oommutating BCachincs.
Synchronous Machines.
Stationary Induction Apparatus.
Rotary Induction Apparatus.
Unipolar or Acyclic Machines.
Rectifsrin^ Apparatus.
Transmission Lines.
Phase-Displacing Apparatus.
[8.
%
D. R^ulation.
Definitions,
t) Conditions for and Tests of Regulation.
B. Insulation.
fl) Insulation Resistance.
(II) Dielectric Strength.
(a) Test Voltages.
(b) Methods ofTeeting.
le} Methods for Measuring the Test Voltage,
(a) Apparatus for Supplying Test Voltage.
F. Conductivity.
G. Rise of Temi>erature.
(I) Meeenrement of Temperature.
Methods.
Nonnal Conditions for Tests.
501
^]
502 STANDARDIZATION RULES.
(II) Limiting Temperature Rise.
Machines m Greneral.
Rotary Induction Apparatus.
Static Induction Apparatus.
Rheostats.
Limits Reoommended in Special Oases.
H. Overload Capacities.
III. VoLTAaBS AND FRBQUBNCnS.
A. Voltages. !
B. Frequencies. |
i
IV. GuNBBAL Recommendations. '
V. Appbndicbs and Tabular Data.
Appbndix a. — Notation.
Appbndix B. — Railway Motors.
(I) Rating.
(II) Selection of Motor for Specified Service.
Appendix C. — Photometry and Lamps.
Appendix D. — Sparking Distances.
Appbndix £. — Temperature Coefficients.
1. NoTB. The following definitions and classifications are intended to
be practically descriptive and not sctentifieatly rigid.
A. DEFINITIONS. CURRENTS.
2. A Direct Current is a unidirectional current.
3. A Continuous Chirrent is a steady, or non-pulsating, direct eurrent.
4. A Pulsating Current is a current equivalent to the superposition of an
alternating current upon a oontinuous current.
5. An Alternating CHirrent is a current which, when plotted, consists of
half-waves of equal area in successively opposite directions from the aero
line.
6. An OsdUating Current is a current alternating in direction, and of
decreasing amplitude.
B. DEFINITIONS. ROTATING MACHINES.
7. A (Generator transforms mechanical power into electrical power.
8. A Direct-CHirrent (venerator produces a direct current that may or
may not be oontinuous.
9. An Alternator or Alternating-Current Generator produces alternating
current, either singl»;phase or polyphase.
10. A Polyphase Cfenerator produces currents differing symmetrically in
phase: such as two-phase currents, in which the terminal voltages on the
two circuits differ in phase by 90 decrees; or three-phase currents, in which
the terminal voltages on the three circuits differ in phase by 1!^ degrees.
11. A Double-Current Generator produces both direct and altenutting
currents.
12. A Motor transforms electrical int-o mechanical power.
13. A Booster is a machine inserted in series in a circuit to change its
voltage. It may be driven by an electric motor (in which case it is termed
a motor-booster) or otherwise.
14. A Motor Generator is a transforming device consisting of a motor
mechanically connected to one or more generators.
15. A Dynamotor is a transforminfl: device combining both motor and
generator action in one magnetic field, with two armatures; or with an
armature having two separate windings and independent commutators.
DEPINITIONS AND TECHNICAL DATA. 503
16. A Canverttt* is a nuushine employing mechanical rotation in changing
el«etrical energy from one form into another. A converter may belong to
flitber of sereriu types, as follows:
17. a. A Direct-Current Converter converts from a direct current to a
direct current.
18. b. A Ssnachronous Converter (commonly called a rotary converter)
converts from an alternating to a direct current, or vice vena.
19. c. A Motor Converter is a combination of an induction motor with
a synchronous converter, the secondary of the former feeding the armature
oC the latter with current at some frequency other than the impressed
frequency; xjb., it is a synchronous converter concatenated with an induc-
tion motor.
20. d. A Frequency Converter converts from an alternating-current
syrtem of one fregueney to an alternating-current svstem of anotho- fre-
quency, with or without a change in the number of phases or in voltages.
21. e. A Rotary Phase Converter converts from an alternating-current
■yston of one or more phases to an alternating-current system of a different
number of phases, but of the same frequency.
C. DEFINITIONS. STATIONARY INDUCTION APPARATUS.
22. Stationary Induction Apparatus change electric energy to electric
energy through the medium of magnetic energy. They comprise several
forma, distinguished as follows:
23. a. In Transformers the primary and secondary windings are insu-
lated from one another.
24. b. In Auto-Transformers, also called compensators, a part of the
primary winding is used as a secondary winding, or conversely.
25. e. In Potential Regulators a coil is in shunt and a coil is in series
with the circuity so arrani^ that the ratio dt transformation between them
is variable at will. They are of the foUowing three classes:
25. (a) Compensator Potential Regulators in which a number of turns
of one of the coUs are adjustable.
27. (6) Induction Potential Regulators in which the relative positions
cf the primary and secondary coils are adjustable.
28. (c) Ifagneto Potential Regulators in which the direction of the
maoietic flux with respect to the coils is adjustable.
29. d. Reactors, or Reactance Coils, formerly called choking coils, are a
form of stationary induction apparatus used to produce reactance or phase
(fisplaoemeat.
D. GENERAL CLASSIFICATION OF APPARATUS.
30. CoiiMiTTATTNO Macrinss. Under this head may be classed the
following: Direct-current generators; direct-current motors; direct-current
boosters; motor-generators; dvnamotors; converters, compensators or
balancers; cdoeed-coil arc machines, and alternating-current commutating
notorB.
31. Commutating machines may be further classified as follows:
32. a. Direct-Current Commutating Machines, which comprise a mag-
netie fidd of constant polarity, a closed-coil armature, and a multiseg-
mental commutator connected therewith.
33. 6. Alternating-Current Commutating Machines, which comprise a
magnetic fi^d of alternating polarity, a closed-coil armature, and a multi-
segmental commutator connected therewith.
34. e. Synchronous Commutating Machines, which comprise ss^ohro-
ootti converters, motor converters and double-current generators. ,
35. Synchronous Machines, which comprise a constant magnetic field,
and an armature receiving or delivering alternating-currents in synchron-
ism with the motion of the machine; i.e., having a frequencv equal to the
product of the number of pairs of poles and the speed of the machine in
revolutions per second.
36. Stationary Induction Apparatus, which include transformers, auto-
tnuMformen, potential regulators, and reactors or reactance coils.
{
604 BTANDABDIZATION RULES.
87. Kotanr Induotlon Apparatus, or Induction Maehines, which ladiida
apparatus wherein the primary and secondary windinsi rotate with reopeet
to each other; ».«., induction motors, induction generators, frequency CKut*
▼ertera and rotary phase converters.
38. Unipolar or Acyclic liachines, in which the voltage generated in the
active conductors maintains the same direction with respect to thoae
CX>nductorB.
30. Rectifjring Apputitus, Pulsating>Current Generators.
40. Electrostatic Apparatus, such as condensers, etc.
41. Electrochemical Apparatus, such as batteries, etc.
42. Electrothermal Apparatus, such as riieoetats, heaters, eto.
43. Protective Apparatus, such as fuses, lightning arresters, eto.
44. Luminous Sources.
E. MOTORS. SPEED CLASSIFICATION.
45. Motors may, for convenience, be classified with reference to their
•peed characteristics as follows:
46. a. Constant-Speed Motors, in which the speed is either constant or
does not materially vary; such as synchronous motors, induction motofs
with small slip, ana ordinary direct-current shunt motors.
47. b. Multispeed Motors (two-speed, three-speed, etc.). which can be
operated at any one of several distinct speeds, these speeos beins praeti-
eally independent of the load, such as motors with two armature winding.
48. e. Adjustable-Speed Motors, in which the speed can be varied grad-
ually over a considerable range; but when once adjusted remains pract^
oally unaffected b^ the load, such as shunt motors designed for a oonsiaerable
ranse of field variation.
49. d. Varyin^-Speed Motors, or motors in whidi the speed varies
the load, decreasing when the load increases; such as series motors.
F. DEFINITION AND EXPLANATION OF TERMS.
(I) Load Factor.
60. The Load Factor of a machine, plant^ or system is the ratio at the
average power to the maximum power dunng a certain period of time.
The average power is taken over a certain interval of time, such as a day
or a year, and the maximum is taken over a short interval of the maxim^nm
load within that interval.
61. In each case the interval of maximum load should be definitely
specified. The proper interval is usually dependent upon local conditSoas
and upon the purpose for which load factor is to be determined.
(II) Non-Inductxve Load and Inductive Load.
52. A Non-inductive Load is a load in which the current is in phase with
the voltage across the load.
53. An Inductive Load is a load in which the current laas behind the
voltage across the load. A load in which the current leaoi the ventage
across the load is sometimes called an anti-inductive load.
(III) Power Factor and Reactive Factor.
64. The Power Factor in alternating-current circuits or apparatus is tiis
ratio of the electric power in watts to the apparent i>ower in volt-amperes.
It may be expressed as follows:
true power watts energy current energy voltage
apparent power volt-amperes total current total voltage '
^, 65. The Reactive Factor is the ratio of the wattless volt-amperes («.<..
the product of the wattless component of current by voltage, or wattless
somponent of voltage by current) to the total amperes. It may be ex-
/ pressed as follows:
wattless volt-amperes wattless current wattless voltage
total volt-amperes total current total voltage
DEFINITION8 AND TECHNICAL DATA. 506
M. Foif«r Factor and RaaeUve Faotor are related aa foUom:
H 9 «- power factor, q ■> reactive factor, then with nne waves of voltaae
Ufd emrent,
j>» + a» - 1.
With distorted waves of voltage and current,
p» + fl* — or < 1.
(IV) atdwntion Factor.
57. The Saturation Factor of a machine is the ratio of a sniaD jperoenta^
bersaM in field excitation to the corresponding percentage increase m
Toltsge thereby produced. The saturation factor is, therefore, a criterion
of the degree ot saturation attained in the magnetic circuits at any ezcita-
tion aeteeted. Unless otherwise specified, however, the saturation faotor
of s machine refers to the excitation existing at normal rated speed and
tclta^. It is determined from measurements of saturation made on open
anmt st rated speed.
n. The Percentage of Saturation of a machine at any excitation may
be found from its saturatiop curve of generated voltage as ordinates, against
tzdtation as abscissas, h}[ drawing a tangent to the curve at the ordinate
eorresponding to the assigned excitation, and extending the tangent to
Btcreept the axis of ordinates drawn throu^ the origin. The ratio of the
fateroept on this axis to the ordinate at the assijEned excitation, when
ejiiuened in percentage, is the percentage of saturation, and is independent
of tht aesle selected for excitation and voltage. This ratio is equal to
^ redjprooal of the saturation factor at the same excitation, deducted
nom uuty. Thus, if / be the saturation faotor and p the percentage of
atantion ratio.
00 Yarialum and PuUaUon,
59. The Variation in Prime Movers whidi do not give an absolutely
snirotin rate of rotation or speed, as in reciprocating steam engines, is the
OKzimiim angular displacement in position of the revolving member ex-
iniBou] in degrees, from the position it would occupy with uniform rotation,
sad with one revolution taken as 360°.
60. The Pulsation in Prime Movera is the ratio of the difference between
the mairimum and iwwitnnm velocities in an engine-cycle to the average
nloeity.
61. The Variation in Alternators or alternating-current circuits in gen-
ttal is the nuurimnm difference in phase of the generated voltage wave from
^ wave of absolute^ constant freauency, expressed in electrical degrees
(one eyele squals 360r) and may be due to the variation of the prime mover.
^. The Pulsation m Alternators or altematin^urrent circuits, in gen-
wu. is the ratio of ti^e difference between maximum and minimum fre-
Qoney during an engine-eyde to the average frequency.
w. Rehition of Variation in prime mover and alternator.
64. If fi «■ number of pairs of poles, the variation of an alternator is n
^MB the variation of its prime mover, if direct connected, and n/p times
(he ^rariation of the prime mover if rigidly connected thereto in the velocity
laHop.
A. RATING.
65. Ratiho bt Output. All electrical apparatus should be rated by
?B^ut and not by input. Generators, transformere, etc., should be rated
HA n^^ output, motors by mechanical output.
«J!!l '^'I'lMo o* KnowATTB. Electrical power should be expressed in kilo-
tn" V^^*^ ^^*^ otherwise specified.
i^2jl A'^abint Powbb, KxL0Voia*-AuPB]ai8. Apparent power in altemat-
"t'^onent dreuits should be expressed in kilovolt>amperes as distinguished
i
506 STANDARDIZATION RULES.
from real power in Idlowatta. When the power factor is 100 per cent* the
apparent power in Idlovolt-amperes ia equal to the kilowatts.
68. The Rated (Full-Load) Current is that current which, with the rated
terminal voltage, gives the rated kilowatts, or the rated kilo vol t-ampavB.
In machines in which the rated voltage differs from the no-load voltage
the rated current should refer to the former.
60. Dbtbrmination of Rated Currbnt. The rated earrent may be d»-
termined as follows: If P — rating in watts, or apparent watts if the power
factor be other than 100 per cent, and E = full-load terminal voltage, ihtt
rated current per terminal is:
p
70. / -> -g in a direct-current machine or single-phase alternator.
1 P
71. / — -7= Bi in a three-phase alternator.
V 3 ^
1 P
72. / » ^ ^ in a two-phase alternator.
73. Normal CoNDmoNS. The rating of machines or apparatus shouM
be based upon certain normal conditions to be assumed as standard, or
to be specified. These conditions include voltage, current, power factor,
frequency, wave shape and speed; or such of them as may apply in each
particular case. Performance tests should be made under these standan!
conditions unless otherwise specified.
74. a. Power Factor. Alternating-current apparatus should be rated
in kilowatts, at 100 per cent power factor; i.«., with current in phase with
terminal voltage, unless a phase displacement is inherent in tbe apparatoa*
or is specified. If a power factor other than 100 per cent is specified
the' rating should be expressed in kilovolt-amperes and power factor, a£
rated loadf.
75. .6. Wave Shape. Id determining the rating of altematinc-carrezit
machines or apparatus, a sine wave shape of alternating current and voltage
is assumed, except where a distorted wave shape is inherent to the appa-
ratus. See Sees. 79-83.
76. Fuses. The rating of a fuse should be the m^Titni^m euxtent which
it will continuously carry.
77. Circuit Breakers. The rating of a circuit breaker should be the
It is to be noted that the behavior of fuses and of circuit breakers is mueh
influenced by the amount of electric power available on the oirouit.
B. WAVE SHAPE.
79. The Sine Wave should be considered as standard, except where a
difference in the wave form from the sinusoidal is inherent in the operatkn
of the apparatus.
80. A Maximum Deviation of the wave from sinusoidal shape not exceed-
ing 10 per cent is permissible, except when otherwise specified.
81. The Deviation c^ wave form from the sinusoidal is measured by
determining the form by oscillograph or wave meter, computing therefrom
the equivalent sine wave of equal length, superposing the latter upon the
observed wave in such a manner as to give least difference, and then dividt*
ing the maximum difference at any ordinate by the maximum value of the
equivalent sine wave.
82. The Equivalent Sine Wave is a sine wave having the same frequency
and the same effective or r.m^i. (root of mean square) value as the actna^
wave.
83. NoN Sine Waves. The phase displacement between two waves
which are not sine waves, is that phase displacement between th^r equiv-
alent sine waves which would give the same average product of instan-
taneous values as the actual waves; i.e., the same electro-dyxuunometer
reading.
PEKFOBMANCE SPECIFICATIONS AND TESTS. 507
C. EFFICIENCY.
(I) Definiliona.
84. The eifieiency of an apparatus is the ratio of its net power output to
its avaa power input.
85. a. NoTB. An exception should be noted in the case of storage bat-
teries or apparatus for storing energy in which the efficiency, unless other-
wise qualined, should be unoerstocva as the ratio of the energy output to
the eoetgy intake in a normal cycle. An exception should also be noted in
the case of luminous sources.
86. Appaunt EmcisNCT. In apparatus in which a phase displace-
ment is inherrait to their operation, apparent efficiency should be under-
stood as the ratio of net power output to volt-ampKere input.
87. a. NoTX. Such apparatus comprise induction motors, reactive syn-
ehronous converters, synchronous converters controlling the voltage of an
alternating-currait system, setF-exciting synchronous motors, potential
renUators and open magnetic circuit transformers, etc.
88. 6. Noix. Since the apparent efficioicy of apparatus delivering
electric power depends upon the power factor of the load, Che apparent
cffioeoor, unless otherwise specified, should be referred to a load power
factor 01 unity.
(tl) Ikterminalion of Efficiency.
80. MxTHODB. Elffidency may be determined by either of two methods,
tiz.'. by measurement of input and output; or. by measurement of losses.
90. d. licTHOD or Input and Output. Toe input and output may
both be measured directly. The ratio of the latter to the former is the
tit. b. Hbthod bt Loeeaa. The losses may be measured either t)ol-
loelively or iadividually. The total losses may be added to the output to
derive the input, or subtracted from the input to derive the output.
02. OoMPARiaoN OP Mbthods. The output and input method is
preferable with small machines. When, however, as in the case of large
maduneB, it is impracticable to measure the output and input, or when
thepCTrontage of power loss is small and the efficiency is nearly unity, the
method of determining efficiencv by measuring the losses should be followed.
03. Electrio Power should be measured at the terminals of the appa-
ratus. In tests of polyphase machines, the measurement of power should
not be confined to a sinpe circuit, but should be extended to all the cir-
emts in order to avoid errors of unbalanced loading.
94. Medianieal Power in machines should be nteasured at the pulley,
gearing, coupling, etc., thus excluding the loss of power in said pulley,
gearing or ooaplin||, but including the bearing friction and windage. The
magnitude of bearing friction and windagn may be considered, with con-
itaat speed, as independent of the load. The loss of power in the belt and
the inereaae of bearing friction due to belt tension should be excluded.
Where, however, a machine is mounted upon the shaft of a prime mover
ia such a manner that it cannot be separated therefrom, toe frictional
jOMHij in bearin0i and in windage, which ought, by definition, to be included
ia determining the efficiency, should be excluded, owing to the practical
impossibility of determining them satisfactorily. ^
95. In Auxiliary Apparatus, such as an exciter, the power lost in the
undliary apparatus snould not be charged to the {principal machine, but
to die luant consisting of principal nuushme and auxiliary apparatus taken
together. The plant efficiency m such cases should be distmguished from
the madune efficiency.
96. NoBMAi« OoNomoNB. Efficiency tests should be made under normal
jBooditions herein set forth and which are to be assumed as standard,
nese oooditions indude voltage, current, power factor, frequency, wave
uape, speed and barometric pressure, temperature, or such of them as
nunr apply in each particular case. Performance tests should be made
■Kter tnese standard conditions unless otherwise specified. See Sees.
7»-75.
97. a. Tbmperatubk. The effioiency of all apparatus, except such as
nuy be intended for intermittent service, ohould be either measured at, or
nduoed to, the temx>erature which the apparatus assumes under continuous
508 STANDARDIZATION RULES.
operation at rated load, referred to a room temperature of 28* C. Sm
Sees. 267-202.
08. With apparatus intended for intermittent eervioe, the efficieaor
■hould be determined at the temperature assumed under specified ooa<a>
tions.
00. b. PowiB Factoh. In determining the effidenoy of altematinc-
ourrent apparatus, the electric power should be measured when the cuiieui
ii in phase with the voltage, unless otherwise specified^ except when a
definite phase difference is inherent in the apparatus, as in induction motossi
induction ffenerators, frequency converters, etc.
100. c. Wavb Shapb. In electrical apparatus, the sine wave ehouid be
eonflidered as standard, except where a dmerenoe in the wave form froca
the sinusoidal is inherent in the operation of the apparatus. See Sees.
70-83.
(Ill) MetuuremetU of Lottea.
101. LoesBS. The usual sources of loasee in electrical apperatua awl
the methods of determiniuK these losses are as fottows:
(A) Bbabotq Fbiction and Windaob.
102. The magnitude of bearing friction and windage (which ramjr be
eonsidered as independent (rf the load) is conveniently measured by dnviiig
the machine from an independent motor, the output of which may be aiiitabty
detennined. See Sec. 04.
(B) OOMMUTATOB BbUSH FbICTION.
108. The magnitude of the commutator brush friction (which nmy be
considered as independent of the load) is determined by meaaurins the
difference in power required for driving the machine with broshea on aod
with brushes off (the field being unexoited).
(C) Ck>LLBcroB-RiNa Bbubh Fbiction.
104. Collector-ring brush friction may be determined in the same meiuMr
as commutator brush friction. It is usually negligible.
(D) MouBCULAB Maqnbtic Fbiction and Eddt Cubbbnts.
106. These losses include those due to molecular magnetic frieti<» aad
eddy currents in iron and coppa- and other metallic pairts, also the
due to currents in the crossHM>nneotioiis of eross-oonneeted aimatures.
100. In Machines these losses should be determined on open eiromt and
at a voltage equal to the rated voltage -I- /r in a generator, and <- /r in e
motor, where / denotes the current strength and r denotes the intemei
resistance of the machine. They should be measured at the ooireet speed
and voltage, since they do not usually vary in any definite pioportiim to
the speed or to the voltage.
107. NoTB. The Total Losses in bearing friction and windage, brash
friction, magnetic friction and eddy currents, can, in nneral, be detennined
by a single measurement by drivug the machine with the field excited,
either as a motor, or by means of an independent motor.
108. Rbtabdation Mbthod. The no-ioad iron, friction, and windage
losses may be segregated by the retardation method, in which the gen-
erator should be Drought up to full speed (or, if poasible, to about 10 per
cent above full speed) as a motor, and, after cutting off the driving powef
and excitation, frequent readings should be taken of speed and time, as tiM
machine slows down, from which a speed-time curve can be plotted. A
second curve should be taken in the same manner, but with full field exal-
tation ; from the second curve the iron losses may be found by subtraothig
the losses found in the first curve.
100. The speed-time curves can be plotted automatically by belting e
small separately exdted genwator (say 1/10 kw.) to the generator shaft and
connecting it to a recording voltmeter. When the retardation method is
not feasibls, the f rictional losses in bearings and in windage, which ouaht,
by definition, to be included in determining the effidenoy, may be occluded;
but this should be expressly stated.
PEBFORHANCE SPECIFICATIONS AND TESTS. 509
(O AaMXTUTm-RmaufTAMcm Loss.
110. This loss may be expressed by pPr; where r •« resistanoe of one
snoaiars eirouit or oranoh, / — the ciUTsnt in such armatare oiroult or
bnaeh, aad p «» the number of armature circuits or branches.
(F) COMMUTATOB BbUSH AND BbUSH-CoNTACT RbSISTANCB LoSS.
111. It is desirable to point out that with carbon brushes these losses
nsy be considerable in low-voltace machines.
(0) CouMcrott-RjMQ AND Bbusjei-Contact Rbsistamcb Loss.
112. Thb loss is usually negligible, except in machines of extremely low
ToltM^e, or in unipolar machines.
(H) Fuld Excftation Loss.
113. With separately excited fields, the loss of power in the resistance
of the field coils alone should be considered. With either shunt- or series-
ieU wiodinn, however, the loss of power in the accompanying rheostat
riMHiid slso be included, the said rheostat being ponsidered as an essentia)
psrt of the maehine, and not as separate auxiliary apparatus.
O Load LoasoBs.
114. The load losses may be oonsidered as the difference between the
total loBMB under load and the sum of the losses above specified.
115. «. In Cooxmutating Machines of small field distortion, the load
KMMB ate usually trivial and may, therefore, be neglected. When, how^
ever, the field distortion is large, as is shown, for instance, by the necessity
for ^lifting the brushes between no load and full load, or with variations of
load, these load losses may be considerable and should be taken into
sooount. In this case the efficiency may be detwmined either by input
sod OQtput measurements, or the Toad losses may be estimated by the
method of Sec. 116.
116. 6. EsTiifATioN OF Load Lobsbs. While the load losses cannot
vdl be determined Individually, they may be considerable and. therefore,
their iotnt influence should be determined, by observation. This can be
dou by operating the maehine on short-cirouit and at full-load current,
tlttt is, bv determining what may be called the "short-circuit core loss.'*
With the low field intensity and great lag of current existing in this case,
tiie losd losses are usually greatly exaggerated.
117. One-third of the short^ircuit core loss may, as an approximation,
sad in the abeeace of more accurate information, be assumecf as the load
(IV) Bffcieney of DiffmvrU Type$ of AppanUut.
{A) Doacr-CUBSBNT OoMMUTATINO liACHINBS.
118. In Direct-Current Commutating Bfachines the losses are:
110. a. Bbabino Fbiction and Windaqb. See Measuranent of Losses
U), See. 102.
120. b. MoLBCULAB Magnbtic Fbiction and Eddt Cubbbnts. See
Mesiurement of Losses (2>), Sec. 105.
121. e. Abmatubb Rbsibtancb Losbbs. See Measurement of Losses
(B). See. 110.
122. d. CoMMUTATOB Bbubh Fbiction. Scc Measurement of Losses
iB), See. 103.
123. e. CoifMDTATOB Bbush and Bbubh-Contact Rbsistancb. See
MesBBcement of Losses (F), Sec. 111.
^ 124. /. FiBLJ> ExcrrATioN Loss. See Measurement of Losses (H),
See. 113.
125. a. Load LoasBS. See Measurement of Losses (/), See. 114.
128. Norm, b and c are losses in the armature or armature losses,"
«snd f "commutator losses," / "field losses."
510 STANDARDIZATION RULSS.
(B) AlAVBNATINO-CniUIBNT COMMUTATDIO MaCHINBS.
127. In Altematiiig-CurreDt Commutftting MaohineB. the
128. a. Bbarino FaicrioN and Winoagb. See Meaaurement of
iA), Sec. 102.
129. 6. Rotation Loes, measured with the machine at open circuit,
bnuhes on the commutator, and the field exoited by alterxiatixis
when dlriving the machine by a motor.
130. This loss includes molecular ma^etio friction, and eddy
caused by rotation through the magnetic field. Pr losses^ in croa»-coi
tiona of cross-connected armatures, Pr and other losses in anxutture-
and armature-leads which are short-circuited by the brushes as far
these losses are due to rotation.
131. c. Altbrnatino OR Tranbforickr Loss. These losses axe
by wattmeter in the field circuit, under the conditions of test 6. Tk^'
include molecular magnetic friction and eddy currents due to tbe altfl^
nation of the magnetic field, Pr losses in cross-connections of oroaa-ci
nected armatures, Pr and other losses in armature coil and commotalor
l«uia which are short-circuited by the brushes, as far as these losees am
due to the alternation of the magnetic flux.
132. The losses in armature ooib and commutator leads shortr-circuiteA
b^ the brushes, can^ be separated in 6 and c, from the other loeeee, by ruH
mng the machine with and without brushes on the commutator.
133. d. Pr Loss, other Load Losses in armature and compensatiac
winding and Pr loss of brushes, measured by wattmeter connected mioM
the armature and compensating winding.
134. a. FimiJ> ExcrrATioN Losa. See Measurement of LooBeg iS),
Sec. 113.
135. /. CoicifUTATOR Brubh Friction. See Meosarement of I ouuee iBh
Sec. 103.
(C) Synchronous Comuutatino Machinxs.
130. 1. In Double-Current Generators, the effieienev of the mn^'n^
•hould be determined as a direct-current generator, and also as an alter>
nating-current generator. The two values of efficiency may be diffeteBt*
and should be cleariy distinguished.
137. 2. In Gonvertere the losses should be determined when driving the
machine by a motor. These losses are:
138. a. Bbarino Friction and Winoaob. See Measurement of
(A), Sec. 102.
139. 6. Molbcular Maonbtic Friction and Eddt Currbntb.
Measurement of Losses (D), Sec. 105.
140. e. Armaturb Rbbistancx Lobs. This loss in the armatore it
ql*r, where / >■ direct current in armature, r ■- armature resistance and q,
a factor whieb is equal to 1.47 in single-circuit single-phase. 1.15 in doubl^
circuit single-phase, 0.59 in three-pnase, 0.39 in two-phase, and 0.27 io
six-phase oonvertera.
141. d. Commutator-Brush Friction. See Measurement of Losss
iB). Sec. 103.
142. e. CoLLBCTOR-RiNO Brubh Friction. See Measurement of Laesai
(C), Sec. 104.
143. /. CoMHUTAToR-BRtTSH AND Brubb-Contact Rbbibtancb Losa
See Measurement of Losses (F), Sec. 111.
144. g. CoLLBcroR-RiNG JBrush-Contact Rbbistancb Loss. See Meas-
urement of Losses (G), See. 112.
145. A. Fibld Excftation Loss. See Measurement of Losses (H), Sec. I09«
146. t. Load Lobseb. These can generally be neglected, owing to the
absence of field distortion.
147. 3. The Efficiency of Two Similar Converters may be determined
by operating one machine as a converter from direct to alternating, and tba
other as a converter from alternating to direct, connecting the altematiiig
sides together, and measuring the difference between the direct-eunent
input and the direct-current output. This process may be modified by
returning the output of the second machine through two boosters into the
first machine and measuring the losses. Another modification is to siq>ply
the losses by an alternator between the two machines, using potential
regulatoiB.
I
%
j PERFORMANCE SPECIFICATIONS AND TESTS. 611
p) SnrcHiiONOUS Uachinbb.
148. In Qsmduonous Machines the loases are:
149. a. Bbasinq Fbiction and Windaob. See Measurement of LooBei
. See. 102.
SO. b, MoLBCiTX^AB Magnetic Friction and Eddt Cubbbnts. See
ent of LoflMB (D), Sec. 105.
ISl. e. Armatubb Rbbibtancb Loee. See Meaaurement of LoeMs (£),
e.110.
US. d, OoLXBcroB-RiNO Bbush Friction. See Meaaurement of
(O. See. 104.
153. e. Oollsctor-Rino Brush Contact Rbsistancb Lobs. See
t of Losses (G), Sec. 112.
L 154. f. Fibld Excitation Loss. See Measurement of Losses (/T), Seo.
155. a. Load Xxmsbs. See Measurement of Losses (/), Sec. 114.
9) SxATioNAjrr iNDucrioN Apparatus.
150. In Stationary Induction Apparatus, the losses are:
157. a. Molecular Magnetic Fnetion and Eddy Currents measured at
Qpea seeondary circuit, rated frequenc;)r, and at rated voltage — Ir, where
1 ■• imted current, r — resistance of prunary circuit.
158. 6. Resistanoe Losses, the sum of the Pr losses in the primary and
h. the seeondary windings c^ a transformer, or in the two sections of the
ea0 in a compensator or auto-transformer, where / ■■ rated current in the
toil or seetion of eoil, and r ■- resistanoe.
159. c. Load Looses, t.«., eddy currents in the iron and especially in the
copper conductors, caused by the current at rated load. For practical
twirjinsw they may be detennined by short-circuiting the seconfJUiry of
the tnosformer and impressing upon the primary a voltage su£5eient to
Knd imted load current through the transxormer. The loss in the trans-
former under these conditions measured by wattmeter gives the load losses
+ Pr kmes in bothprimary ijlid seoondatp^ coils.
150. In Closed Circuit Tn^pformers either of the two circuits may be
uwd ■■ raimary when determiiking the efficiency.
151. In Potential Renilators. the efficiency should be taken at the
maximiiin voltage for which the apparatus is designed, and with non-
UMsetive load, unless otherwise specified.
C^' ROTART iNDUCnON APPARATUS, OR INDUCTION MaCHINBS.
162. In Rotary Induction Apparatus, the losses are:
/ }^ ''' Bbarino Friction and Windagb. See Measurement of Losses
W). Sec. 102.
154. 6. Molecular Magnetic Friction and Eddy Currents in iron, copper,
•M other metallic parte; also Pr losses which may exist in multiple-circuit
*]^nCi. a and 6 together are determined by running tiie motor without
lie* »ted voltage, and measuring the power input.
156. c. Primary Pr Loss, which may be determined by measurement
« the current and the resistanoe.
^JJj*- ^- Secondary Pr Loss, which may be determined as in the primary,
^n feseible; otherwise, as in squirrel-cage secondaries, this loss is meae-
ww as part of e.
157. e. Ixiad Losses; i.e., molecular magnetic friction, and eddy currente
miioQ, copper, etc.. caused by the stray field of primary and secondary
g™»ts, and seoondarv Pr loss when undeterminable under d. These
"MM may for practical purposes be determined by measuring the total
J^*^« vith the rotor shortp-cirouited at standstill and a current in the
pnmuy oreuit equal to the primary energy current at full load. The loss
PjMmotor under these conditions may be assumed to be equal to the
"fl iones + Pr losses in both primary and secondary coils.
«?) UmpoLAR OR Acyclic Machinba.
iSo* ^ S*^^^^ Machines, the losses are:
M\<L "•,]^^*'^Q Friction and Windagb. See Measurement of Losses
). Sec. 102.
ul?' ^- MoLBCULAR Magnbtic Friction AND Eddy Cubbbnts. See
***««n»«t of Losses {E), Sec. 106.
512 STANDARDIZATION RUUBS.
171. e. Abmatubb Rbsistakgb Loaswi. See ICeaauremenC o£
(J^, Seo. 110.
172. d. CoLLBCTOR Brush Friction. See Measurement of
Seo. 104.
173. e. Ck>LLacroR Brush Contact Rjbsbtancb. See Men
Looses (G). Seo. 112.
174. /. Field Excitation as in Seo. 113. See Measuremeot ot
(H). See. 113.
175. g. Load Lossbs. See Measurement of Losses (/), See. 114.
iH) RRCTimNO Apparatus, Pulsating-Currbnt Grnkratobs.
176. This Division Includes: open-ooil arc machines and mechanioat'
and other rectifiers.
177. In Rectifiers the most satisfaetoiy method of deterxnininK the
efficiency is to measure both electric input and electric output by vat^i
meter. The input is usually inductive, owing to phase diaputeement aail '
to wave distortion. For this reason the power factor ana the uppmnaA I
efficiency should also be considered, sinoe the latter m^ be mucb lower I
than the true efficiency. The power consumed by auxiliary devioesL svdb |
as the synchronous motor or ooolinc devices, should be included m the i
electric input. |
178. In Gonstant-Current Rectifiers, transfonninc from constant poteo- ;
tial alternating to constant direct current, bv means of oonstaot-ouii aut ,
transforming devioes and rectifying devices, the losses in the tranaf ormiag
devices are to be included in determining the efficiency and have to be |
measured when operating the rectifier, since in this case the loesea may be
greater than when feeding^ an alternating secondary circuit. In ooastaat-
current transforming devices, the load losses may be considerable and.
thwefore, should not be neglected. i
179. In Open Coil Arc Machines, the losses are essentially the same as ia j
direct-current (closed coil) commutating machines. In this case, however, f
the load losses are usually greater, and the efficiency should prefttably be
measured by input- and output-test^ using wattmeters for meaeuriag ths
output. In alternating-current rectifiers, the output should, in genera^
be measured bv wattmeter and not by voltmeter and ammeter, since owing
to pulsation of current and voltage, a considerable discrepancy may exist
between watts and volt-amperes. If. however, a direct-current and an
alternating-current meter in the rectified circuit (either a voltmeter or aa
ammeter) give the same reading, the output may be measured by diieel*
ouirent voltmeter and ammeter. The type of altemating-eurrent insti»>
ment here referred to should indicate the effective or root-of-mean-etiaafa
value and the type ci direct-current instrument the aritfameticel
value, which wouJa be sero on an alternating-current dreuit.
(/) Transmission Linrs.
180. The Efficiency of transmission lines should be measured with ».^
inductive load at the receiving end, with the rated receiving voltage and
frequency, also with sinusoidal impressed wave form, except n^i^e ea>
pressly specified otherwise, and with the exclusion of tranafonnen or other
apparatus at the ends of the line.
(/) PHASR-DlSPLACINa APPARATUS.
181. In Apparatus Producing Phase Displacement as, lor example
synchronous compensators, exciters of induction generators, reactors, eoe-
densers. polarisation cells, etc.^ the efficiency should be understood to be
the ratio of the volt-amperes minus power loss to the volt-amperes.
182. The Efficiency may be calculated bv determining the losses. sub»
traoting them from the volt-amperes, and then dividing the difference by
the volt-amperes.
183. In Synchronous Compensators and exciters of induction geneia'
tors, the determination of losses is the same as in other aynihroaoim
machines.
184. In Reactors the losses are molecular magnetic friction, eddy Iosbsb
and Pr loss. They should be measured b^ wattmeter. The effieieney of
reactors should be determined with a sine wave of impressed voitagt
except where expressly specified otherwise.
PERFORMANCE SPECIFICATIONS AND TESTS. 513
•
185. In Condeiiaera. the losses are due to dielectric hysteresis and leakage,
amd should be determined by wattmeter with a sine wave of voltage.
186. In Polarization Oells, the losses are those due to electric resistivity
aad A loss in the electrolyte of the nature of chemical hysteresis. These
Ifiwim may be considerable. They depend upon the frequency, voltage
and temperature, and should be determined with a sine wave of impressed
Toltaee, except where expressly specified otherwise.
D. REGULATION.
(I) Definitions.
1S7. DEFiNmoN. The regulation of a machine or apparatus in regard
to sovne characteristic quantity (such as terminal voltage, current or si>eed)
is the ratio of the deviation of that quantity from its normal value at rated
load to the normal rated-load value. The term "regulation," therefore, has
the same meaning as the term "inherent regulation/' occasionally used.
IHS. Constant Standard. If the characteristic quantity is intended to
remain constant (e.(7., constant voltage, constant speed, etc.) between rated
load and no load, the regulation is the ratio of the maximum variation
from the rated-load value to the no-load value.
189. Vartinq Standard. If the characteristic quantity is intended to
vary in a definite manner between rated load and no load, the rejiulation is
the ratio of the maximum variation from the specified condition to the
normal rated-load value.
190. (a) Note. If the law of the variation (in voltage, current, speed,
etc.) between rated load and no load is not specified, it should be assumed
to be a simple linear relation; i.e., one undergoing uniform variation between
rated load and no load.
191. (6) Note. The regulation of an apparatus may, therefore, differ
according to its qualification for use. Thus, the regulation of a compound-
wound gmerator specified as a constant-potential generator will be different
from that which it possesses when specified as an over-compounded gen-
erator.
192. In Constant-Potential Machines, the regulation is the ratio of the
maximum difference of terminal voltage from the rated-load value (occur-
ring within the range from rated load to open circuit) to the rated-load
terminal voltage.
193. In Constant-Current Machines, the regulation is the ratio of the
maximum difference of current from the rated-load value (occurring within
the range from rated load to short circuit, or minimum limit of operation),
to the rated-load current.
194. In Constant-Power Apparatus, the regulation is the ratio of maxi-
mum difference of power from the rated-load value (occurring within the
razure of operation specified) to the rated power.
195- In Constant-Speed Direct-Current Motors and Induction Motors
the r^n^lation is the ratio of the maximum variation of speed from its rated-
load value (occurring within the range from rated load to no load) to the
rated-load speed.
196. The regulation of an induction motor is, therefore, not identical
with the slip of the motor, which is the ratio of the drop in speed from
83mchroniszn, to the ^nchronous speed.
197. In Constant-rotential Transformers, the regulation is the ratio of
the rise of secondary terminal voltage from rated non-inductive load to
no loflwl (at constant primary impressed terminal voltage) to the second-
ary terminal voltage at rated load.
108. In Over-Compounded Machines, the regulation is the ratio of the
maximum difference in voltage from a straight line connecting the no-
load and rated-load values of terminal voltage as function of the load
current, to the rated-load terminal voltage.
199. In Converters, Dsmamotors, Motor-Generators and Frequency
Converters, the regulation is the ratio of the maximum difference of ter-
minal voltage at the output side from the rated-load voltage, to the rated*
load voltage on the output side.
200. In Transmission Lines, Feeders, etc., the regulation is the ratio of
Che maximum voltage difference at the receiving end, between rated non-
inductive load and no load to the rated-load voltage at the receiving end
(with constant voltage impressed upOn the sending end).
614 STANDARDIZATION RULES.
201. In Steam Engines, the regulation is the ratio of the niAxiinidB
variation of speed in passing slowly from rated load to no load (with ooi^
■tant steam pressure at the throttle) to the rated-load speed. For v&riatiov
and pulsation see Sees. 50-64.
2102. In a Hydraulic Turbine or Other Water Motor, the raculation m
the ratio of the maximum variation of speed in passing slowly from ratad
load to no load (at constant head of water: t .«., at constant differenoe of
level btetween tau race and head race), to the rated-load speed. For vai^
iation and pulsation see Sees. 59-64.
'203. In a Generator Unit, consisting of a generator united with a prune
mover, the regulation should be determined at constant conditions of the
{>rime mover; t.e., constant steam pressure, head. etc. It ini^ttdaa tlia
nherent speed variations of the prime mover. For this reason the ragiK
Iation of a generator-unit is to oe distinguished from the regulation of
either the pnme mover, or of the generator contained in it, wheo takMi
separately.
(II) CondUiona for and Tetta of ReffuUUion.
204. Speed. The Regulation of Generators is to be determined at
constant speed and of alternating apparatus at constant impresaed fre»
quency.
205. Non-Inductivb Load. In apparatus generating, transforminc; os
transmitting alternating currents, regulation should be underatooa^ to
nfer to non-inductive load, that is, to a load in which the eurreiit is in
phase with the E.M.F. at the output side of the apparatus, except whi
expressly specified otherwise.
206. Wave Form. In alternating apparatus receiving deotrio poi
regulation should refer to a sine wave of E.M.F.. except where
specified otherwise.
207. Excitation. In commutating machines, rectifying machines, and
synchronous machines, such as direct-current generators and motors,
sJtemating-current and polyphase generators, the regulation is to be deter-
mined under the following conditions:
(1) At constant excitation in separately excited fields.
i2) With constant resistance in shunt-field circuits, and
(3) With constant resistance shunting series-fidd dreuits; «.«., the
field adjustment should remain constant, and should be so chosen as to
give the required full-load voltage at full-load currmt.
208. Impedance Ratio. In alternating-current apparatus, in addition
to the non-inductive regulation, the impedance ratio of the apparatus
should be spedfied; i.e.. the ratio of the voltage consumed by me total
internal impedance of the apparatus at full-load current, to its rated fuO-
load voltage. As far as possible, a sinusoidal current should be used.
209. Oomputation of Regulation. When in synchronous machines
the regulation is computed from the terminal voltage and impedance vol-
tage, the exciting ampere-turns corresponding to terminal vintage plus
armature-resistance-drop, and the ampere-turns at short-dreuit eoues
ponding to the armature-impedance-drop, should be combined veotoriaOy
to obtam the resultant ampere-turns, ana the corresponding internal £ Jf ^.
should be taken from the saturation curve.
e. insulation.
(I) Iruulation Reaiatance.
210. Insulation Resistance is the ohmic resistance offered by an insu-
.j^ lating coating, cover, material, or support to an impressed voltage, tending
ur to produce a leakage of current through the same.
211. Ohmic Resistance and Dielectric Stbbnotb. The ohmio
resistance of the insulation is of secondary importance only, as eomnared
with the didectric strength, or resistance to rupture by hig^ voltage. Sinoe
^ the ohmic resistance of the insulation can be very greatly increased by
.i baldng, but the didectric strength is liable to be weakened thereby, it m
preferable to specify a high didectric stren^, rather than a hi^ insula-
tion resistance. The high-voltage test for didectric strength sbooid always
be applied.
212. Recommended Value or Resistance. The insulation reststanee
of complete apparatus should be such that the rated voltage of the appa-
PERFOBMANCE SPBaHCATIONS AND TESTS. 615
will not send more than i qqoooo °^ ^^ ratad-Ioad eumnt, at the
XBtad terminal voltace, throu^ the insulation. Where the value found in
tbis way eoceeede 1 mefohm, it ia usually luffioient.
213. Imnilation Reeistanoe Tests should, if possible, be made at the
for which the apparatus is designed.
(U) Dideetnc Strmtgth.
214. DBvmrrioN;. The dieleetrio strength of an insulating wall, ooat-
Ibs, eover or nath is measured by the voltage which must be applied to it
efleet a disruptive discharge through the same.
inoider to
215. Bamb por DBTBmmiNO Tbst Voltaobs. The test voltage which
ithAii'^ be applied to determine the suitability of insulation for commer-
cial operation is dependent upon the kind and sise of the apparatus and
its ncnmal operating voltage, upon the nature of the service in which it
is to be used, and the severity of the mechanical and electrical stresses to
wfaidi it may be subjected. The voltages and other conditk>ns of test
whi^ are reoommended have been dettfmined as reesonable and proper
lor the great ma|iority of cases and are proposed for eeneral adoption.
tvenipt men speofio reeeons make a modincanon desirable.
216. GoNnrriON of Apparatus to bb Tb0Tbd. Commercial tests
shoold, in gsncral, be made with the completely assembled apparatus and
not with individual parts. The apparatus should be in good condition,
and high-voltage tests, unless otherwise specified, should be applied before
the "»*^*'"* is put into commercial service, and snpuld not be applied when
the insolBtion resistance is low owing to dirt or moisture. Hi^-voltage
teals should, in graersl, be made at the temperature assumed under nor>
mal opemtioB. Hi^-voltags tests considerably in excess of the normal
voltages, to detemune whether specifications are fulfilled, are admissible
OB Bsw machines only.
217. PoDffTB OP Application of Voltaob. The test voltage should
be socecseively applied between each electric circuit and all other dectric
■reoits including conducting material in the apparatus.
218. Tlie Fbbqubnct of the alternating-current test voltage b, in gen-
enl. immaterial within commercial ranges. When, however, the fre-
qiamt^ has an appreciable effect, as in alternating-current apparatus
of hign ventage and considerable capacity, the rated frequency of the appa-
ratus should DC used.
219. Tablb of Tbatino Voia'aobs. The following voIta|^ are recom-
mended for testing all apparatus, lines and cables, by a continued applica-
tioo for one minute. Tne test should be with alternating voltage having
an effeetive value (or root mean square referred to a sine wave of vol-
tage), given in the table, and preferably for tests of alternating apparatus
at tlie normal frequency of the apparatus.
Rated Terminal Voltage of drouit. Rated Output. Testing VolUge.
. Under 10 kw. . . 1,000 volts.
. 10 kw. and over . 1,500
. Under 10 kw. . . l.fiOO
. 10 kw. and over . 2,000
. Any 3,500
. Any 5.000
Any . . Double the normal
rated voltages.
231. BzoBFTiON. — Transforicbbs. Transfonneri having primarv pros-
sores of from 560 to 6,000 volts, the secondaries of which are directly con-
nected to consumption circuits, should have a testing volta|[e of 10,000
volte, to be applied between the primary and secondary windings, and
also between the primary winding and the core.
222. EzcBPTiON. — Fblo Windings. The tests for field windings
should be based on the rated voltage of the exciter and the rated output of
the maehine of whdcdi the coils are i^ pctft. Field windings of synchronous
motofB and converten, which are to be started by applying alternating
220. Not exeeecfing 400 volts . . .
400 and over, but less than 800 vo'lU
•■ •• •• •• •• ••
800"
■•
(•
1,200
1,200"
*t
*•
2,600
2,600"
t«
J
516
STANDARDIZATION RULES.
current to the armature when the field is not excited and a high voltage j
induoed in the field windinni, should be tested at 5.000 volte.
223. Rated Terminal voltage. — DBPiNmoN. The rated
voltac;eof circuit in the preceding table means the voltaoe between the
ductors of the circuit to which the apparatus to be tested is to be oonn4
•—for instance, in three-phase circuits the delta voltage should be ^
In the following specific cases, the rated terminal voltage of the
to be determined as specified in ascertaining the testing voltage.
224. (a) TRANSFORiaGRB. The test of the insulation between the pi
ary and secondary winding of transformers is to be the same aa
between the high-voltage wmdings and core, and both tests should be
simultaneously by connecting the low-tension winding and core tof, _
during the test. If a voltage equal to the apedfied testing voltage
induced in the high-tension winding of a trannormer it may be
insulation tests instead of an independently indueed voltage. Theae
should be made first with one end and then with the other end of the
tension winding eonnected to the low-tension winding and to the oon
225. (6) GoNafTANT-OuRRBirr Apparatus. The testing voltage is
based upon a rated terminal voltage equal to the maximum voltage
may exist at open or dosed circuit.
226 (e) Appabatus in Sbribs. For tests of machines or apcaiv
%'oita«
be operated in series, so as to employ the sum of their separate _
testing voltage is to be based upon a rated terminal voltiue equiU to
sum of the separate voltages, except where the frames or the maeh
are separately insulated, both from the ground and from eadi other,
which case the test for insulation between machines should be based u|
the voltage of one machine, and the test between each madiine and ^ro*
to be based upon the total voltage of the series.
(B) BIbthodb op Tsstino.
227. Clabsbh op Tests. Tests for dielectric strength cover such
wide range in voltage that the apparatus, methods ana precautions whic
are e^ential in certain cases do not apply to others. For convenience,
testR will be separated into two classes:
228. Class 1. This class includes all apparatus for which the test vol"!
tage does not exceed 10 kilo volts, unless the apparatus is of very lann]
static capacity, e.g.y a large cable system. This class also includes 2^]
apparatus of small static capacity, such as line insulators, switches and th€|]
like, for all test voltages. !
229. Method of Test for Class 1. The test voltage is to be continu-
ously applied for the prescribed interval, — (one minute unless otherwim
specified). The test voltage may be taken from a constant-potential
source and applied directly to the apparatus to be tested, or it may be
raised gradually as specified for tents under Class 2.
230. Class 2. This class includes all apparatus not included in Class I.
231. Method op Test for Class 2. The test voltage is to be raised
to the required value smoothly and without sudden Large increments and
is then to be continuously tipplied for the prescribed interval. — (one
minute, unless otherwise specified), and then gradually decreased.
232. CoNomoNs and Precautions )^r Class 1 and Class 2. The
following apply to all tests:
233. The Wave Shape should be approximately sinu.soidal and the
apparatus in the testing circuits should not materially distort this wave.
234. The Supply Circuit should have ample current-supply capadty so
that the charging current which may be taken by the apparatus under test
will not materially alter the wave form nor materially affect the test volt-
age. The circuit should be free from accidental interruptions.
235. Resistance or Inductance in series with the pnmarv of a rmistng
transformer for the purpose of oontroiline its voltage is Inble seriously
to affect the wave form, thereby causing^ the maximum value of the ^-olt-
age to bear a different and ^unknown ratio to the root mean square value.
This method of voltage adju.stment is, therefore, in general, undesinbie.
It may be noted that if a resistance or inductance is employed to Kmit the
current when burning out a fault, such resistance or Inductance should be
•hort-cirouited during the regular voltage test.
^'
PERFORMANCE SPECIFICATIONS AND TESTS. 517
The Insulation under test should he in normal condition as to dry*
and the temperature should, when possible, be that reached in nonnal
.^.ee. ^
237. A2>DmoKAi« OoNDmoNS and PBXCAirriONa fob Class 2. The
following conditions and precautions, in addition to the foregoing, apply
to tests of apparatus included in Class 2.
238. Sadoen Increment of Testing Voltage on the apiparatus under test
^kould be avoided, particularly at high voltages and with apparatus hav-
oonaiderable capacity, as a momentarily excessive rise in testing voltage
J result.
239. Sadden Variations in Testin^^ Voltage of the circuit supplsring the
-voltage during the test should be avoided as they are likely to set up mjur-
SocB oscillation.
240. Good Connections in the circuits supplying the test voltage are
easentlal in order to prevent injurious high-frequency disturbances from
being set up. When a heavv current is carried by a small water rheostat,
&rctng may occur, causing high-frequency disturbances which should be
earef ally avoided.
241. XBANSFORiCBR CoiLS. In high-teusion transformers, the low-ten-
aoo eoil should preferably be connected to the core and to the ground when
tlie hi^i-tenaion test is being made in order to avoid the stress from low-
tension to core, which would otherwise result through condenser action.
The various terminals of each winding of the high-tension transformer
onder tent should be connected together during the test in order to pre-
vent andae stress on the insulation between turns or septions of the wind«
lag in case the hig^-voltage test causes a breakdown.
(C) MjCTHODS VOB BiSASURINO THS TB8T Voi/FAoa.
242. For Measuring the Test Voltage, two instruments are in eommon
ose, (1) the spark gap and (2) the voltmeter.
243. 1. The Spark Gap is ordinarily adjusted so that it will break dowti
with a certain predetermined voltage, and is connected in paralld with
the insolatJon under test. It insures that the voltage applied to the insu-
latioa is not peater than the^ breakdown voltage of the spark gap. A
|[rven setting m the spark gap is a measure of one definite voltage, and, as
Its operation depends upon the maximum value of the voltage wave, it ia
ntdependent of wave form and is a limit on the maximum stress to which
the insolation is subjected. The spark gap is not conveniently adapted
for comparatively low voltages.
244. In Spark-Gap Measurements, the spark ^p may be set for the
required voltage and the auxiliary apparatus adjusted to eive a voltage
at whiefa this spark gap just breaks down. The spark gap should then be
adjusted for, say, 10 per cent higher voltage, and the auxiliary apparatus
again adjusted to give the voltage of the former breakdown, which is to
be the assumed voltage for the test. This voltage is to be maintained for
the required interval.
245. The Spark Points should consist of new sewing needles, supported
azially at the ends of linear conductors which are each at least twice the
length of the gap. There should be no extraneous body near the gap within
a radius of twice its length. A table of approximate striking distances is
gxven in Appendix D. This table should be used in connection with testa
made by Uie spark-gap methods.
246. A Non-inductive Resistance of about one-half ohm per volt should
be inserted in series with each terminal of the gap so as to keep the dis-
charge current between the limits of one-quarter ampere and 2 amperes.
TTie purpose of the resistance is to limit the current in order to prevent the
■urges which might otherwise occur at the time of breakdown.
247. 2. The Voltmeter gives a direct reading and the different values
cf the voltasB can be read during the application and duration of the test.
It is suitabie for all voltages, and does not introduce disturbances into the
test cireoit.
248. In Voltmetar Measupsments, the voltmeter should, in general,
derive its voltage from the high-tension testing circuit either directly or
throo^ an auxiliary ratio transformer. It is permissible, however, to
measure the voltage at other places, — for example, on the primary of the
tianflfornier, provided the mtio of transformation does not materially vary
during the test, or that proper aeoount is taken thereof.
240. Sfask Gap and Volticbtbr. The spark gap may be employed
618 STANDARDIZATION RULES.
M a eheok upon the voltmeter used in high-tendon tetti In order to
mine the truisf ormatioa ratio of the tranaf ormer, the variation f lom tiM
■ine wave form and the like. It is alao useful in oonjunotion with veil*
meter measurements to limit the stieaB applied to the tmptiUtJnj matcriaL
(D) Apparatus iob Snppi.T»o Tan YovrAam.
250. The Oenerator or CSrouit suppljring voltage for the test should haw
ample current carrying oapaoity, so that ^e current whidi may be takm
for charging the apparatus to be tested will not materially alter the wave
form, nor otherwise materially change the voltage.
The Testing Transformer should oe such that its ratio of tranafomi^
tion does not vary more than 10 per cent, when delivmng the chanciBif
current re9uired by the apparatus under test. (This may oe deienninm
by short-circuiting the secondary or high-voltage winding testing tnms-
former and supplying ^ of the primary voltage to the primary under this
condition. The primary current that flows under this condition is the
maximum which should be permitted in regular dielectric tests.)
251. The Voltage Control may be secured in either of several waye,
which, in order of preferenoe, are as follows:
252. 1. By generator field drouit.
253. 2. By magnetio commutation.
254. 3. By dumge in tranrformer ratio.
255. 4. By resistance or choke coils.
256. In Generator Voltage C>ontrol, the voltage of thtf generator alKNild
preferably be about its approximate normal rated-load value when ths
full testing voltage* is attained, which requires that the ratio of the ra
transformer be such that the full testing volti^ is reached when the
erator voltage is normal. This avoi<ls the instability in the gen
whidi may occur if a considerable leading current is taken from it
it has low voltage and low fidd current.
*257. In Magnetic Commutation, the control is e£Feeted by shunting the
magnetic flux throudi a secondary coU so as to vary the induotion tfarooi^
the coil and the voltage induced in it. The shunting should be effected
smoothly, thus avoiding sudden changes in the induced voltage.
258. In Transformer Voltage Control, by change of ratio, it is iieoei>
sary that the trandtion from one step to another oe made without inteiw
ruption of the test voltage and by steps suflidently small to prevent snrns
in the testing drcuit. The neoeedty of this precaution is greater aa the
inductance or the static oapadty of the apparatus in the »^m*i»|[ eimiit
under test is greater.
250. When Resistance Coils or Reactors are used for voltage oontrol,
it is dedrable that the testing voltage should be secured when the eoo-
troUing resistance or reactance is very nearly or entirely out of dxeuit, in
order that the disturbing effect upon the wave form ^Rwoh resulta may be
negUgible at the bluest voltage.
F. CONDUCTIVITY.
260. CoppBR. The conductivity of copper in dectric wires and eabks
should not be less than 08 per cent of Matthieesen's standard of oondae-
tivity. as defined in the Copper Wire Table of the American Institute of
Electrical Engineers.
G. RISE OF TEMPERATURE.
(I) Meaatsrement of Temperature,
(A) Mbtbods.
261. There are two methods in common use for detennining the rise in
. temperature, viz.: (1) by thermometer, and (2) by increase in resistance of
% an electric circuit.
'* 262. 1. By Thrrmombtbr. The following precautions should be
observed in the use of thermometers:
/263. a. PROTBcriON. The thermometers indicating the room temper*
ature should be protected from thermal radiation emitted by heated booiee,
or from draughts of air, or from temporary fluctuations of temperature.
Several room thermometers should be used. In usiiig the thermometar
PERFORMANCE SPECIFICATIONS AND TESTS. 519
bar applsriac it to a boated part^ eara should be taken so to protect its bulb
a* to prevent radiation from itj and, at the same tinie, not to interfere
sr with the normal radiation from the part to which it is applied.
6. BuLS. When a thermometer is applied to the free surface of a
a, it ia desirable that the bulb of the thermometer should be oov-
b^ a pad of definite area. A convenient pad mav be formed of cotton
a in a shallow circular box about one and a hau inches in diameter,
tfaroon^ a slot in the side in ^irtiioh the thermometer bulb is inserted. An
vaduly latse pad over the thermometer tends to interfere with the natural
fibcratioa of neat from the surface to which the thermometer is applied.
. 2. Bt iNCBBAsa IN RasurTANca. The resistance may be measured
by Wbaatstone bridge, or by drop of potential method. A temper-
«... ^ Q^^ 1^^ ^^^^ P^ degree C. from and at 0^ C, may be
fcad for oopper.
Tha tomperature-ooefficients from and at each degree C. between 0^ C.
and 50^ C. are given in Appendix E. The temperature rise mav be deter-
mined either (1) by divkung the percentage mereaae of initial resistance
by tbe tempeiature-ooeffieient for the initial temperature expressed in per
eent; or (2} by multiplying the inerease in per cent of the initial resistance
by 238.1 pluB the imtial temperature in degrees C, and then divicUng the
pfodnet by 100.
260. 3. Comparison or Mithods. In electrical conductors, the rise
of temperature should be determined by their increase of resistance where
praetioabla. Temperature elevations measured in this way are usually in
exeoss of temperature elevations measured by thermometers. In very
lofw lesBstanoe dreuits, thermometer measurements are frequently more
reliable than measurements by the resistance method. Where a thermom-
eter applied to a coil or winding indicates a hidber temperature elevation
than Sat abown by resistanee measurement, the thennometer indication
shoeld be aeoepted.
<B) NoBiiAZ* Conditions iob Tbsts.
267. 1. DcKATioN OF TasTB. The temperature should be measured
a run of sufficient duration for the apparatus to reach a practically
eiHMiaat temperature. This is usually from 6 to 18 hours, according to
tfM siae and construction of the appaiatus. It is permissible, however, to
sborten the time of the test by running a lesser time on an overload in
earrent and voltage, then reducing the load to normal, and maintaining it
thus until the temperature has become constant.
268. 2. Room 'nMPBiiATnitB. The rise of temperature should be
referred to the standard condition of a room temperature of 25^ C
209. TBMraaATUBa_CoRRBcriON. If the room temperature during the
differenc
from 25^0., correction on* account oi difference in resistance
■bonild be msde by changing the observed rise of temperature by one-half
per cent for each degree C. Thus with a room temperature of 35^ C, the
observed rise of temperature has to be decreased by 5 per cent, and with
a room temperature of 15" C, the observed rise of temperature has to be
Increaead by 5 per cent. In certain cases, such as shunt-field circuits with-
out rheostat, the current stren^^th will be changed by a change oi room
taatperatore. The heat oroduction and dissipation may be thereby afiFected.
Oorreeticm for this should be made by changing the observed rise in tem-
perature in proportion as the Pr loss in the resistance of the apparatus is
altered owing to the difference in room temperature.
270. 3. Babombtbio Pbbsbubb. Vbntilation. A barometric pressure
of 760 mm. and nonnal conditions of ventilation should be oonsiaered as
standard, and the apparatus under test should neither be exposed to draught
nor endooed, except where exprsssly specified. * The barometric pressure
needs to be considered only when dilfering greatly from 760 mm.
271. Babombtbic Prbbsubb Oorrbction. When the barometric
pressure differs greatly from the standard pressure of 700 mm. of mercury, as
at hif^ altitudes, a correction should be applied. In the absence oi more
accurate data, a correction of 1 per cent ot the observed rise in temper-
ature for each 10 mm. deviation from the 700 mm. standard is recommended.
For example, at a barometric pressure of 680 mm. the observed rise of
tmperatiiie is to be reduced by — ^ — • >« 8 per cent.
520 STANDARDIZATION RULES.
(II) lAmiting Temperature Rise.
272. Genbral. The temperature of electrical machinery under rei^uku
service conditions should never be allowed to remain at a point at which
permanent deterioration of its insulating material takes place.
273. Limits Rbcommendbo. It is recommended that the followinc
maximum values of temperature elevation, referred to a Btandard room
temperature of 25^ C, at rated load under normal oonditiona of ventilation
or cooling, should not be exceeded.
(A) Machines in Genbral.
274. In commutating machines, rectifying machines, pulaatinf^-eurreDt
generators, synchronous machines, synchronous oommutatmg machines and
unipolar machines, the temperature rise in the parts specified should not
exceed the following:
276. Field and armature, 50<* C.
276. Commutator and brushy, by thermometer, 55* C.
277. CJolleotor rings, 65° C.
278. Bearings ana other parts of machine, by thermometer, 40^ C.
(B) Rotary Induction Apparatus.
270. The temperature rise should not exceed the following:
280. Electric circuits. 50** C, by resistance.
281. Bearing and other parts of the machine 40* C, by thermometer.
282. In squirrel-cage or short-circuited armatures, 55* C, by thermom-
eter, may be allowed.
(O Stationary Induction Apparatus.
283. a. Transformers for Ck>NTiNuous Service. The tem^^atare
rise should not exceed 50* C. in electric circuits, by resistance; and m otbes
parts, by thermometer.
284. 0. Transformers for iNTERMriTBNT Service. In the case of
transformers intended for intermittent service, or not operating contin-
uously at rated load but continuously in circuit, as in the ordinary case of
lighting transformers, the temperature elevation above the surrounding air-
temperature should not exceea 50° C, by resistance in electric circuits and
by tnermometer in other parts, after the period corresponding to the term
of rated load. In this instAnce, the test load should not be applied until the
transformer has been in circuit for a sufficient time to attain the tempc^r-
ature elevation due to core loss. With transformers for commercial lift-
ing, the duration of the rated-load test may be taken as three houre, umeas
otherwise specified.
285. c. Reactors, induction- and .magneto-regulatora — electric circuits
by resistance and other parts by thermometer, 50* C.
286. d. Large Apparatus. ^I^ar^e genexators, motors, transformera,
or other apparatus in which reliability and reserve overload capacity are
important, are frequently specified not to rise in temperature more than
40^ C. under rated load and 55° C. at rat«d overload. It is, however, ordi-
narilv undesirable to specify lower temperature elevations than 40^0. at
rated load, measured as above.
(D) Rheostats.
287. In Rheostats, Heaters and other electrothermal apparatus, no com-
•ustible or inflammable part or material, or portion liable to come in con-
act with such material, should rise more than 50° C. above the surround-
ag air under the service conditions for which it is designed.
288. a. Parts of RuacitTATS. Parts of rheostats and similar apparatus
rising in temperature^, under the specified service conditions, more than 50*
C, should not contain any combustible material, and should be arranged
or installed in such a manner that neither they, nor the hot air issuing from
them, can come in contact with combustible material.
(E) Limits Recommended in Special Cases.
289. a. Heat Rbbistino Insulation. With apparatus in which the
insulating materials have special heat-resisting qusLties, a higher tempei^
ature elevation is permissible.
PERFORMANCE SPECIFICATIONS AND TESTS. 521
290. b. High Air Tbmpbraturb. In apparatus intended for service
In plaoea of abnonnaily hiffh temperature, a lower temperature elevation
riiould be specified. ...
291. c. Appabatcs Subjbct to Overload. In apparatus which by the
nature <^ its service may be exposed to overload, or is to be used in very
hi^voltace circuits, a smaller rise of temperature is desirable than in
apparatus not liable to overloads or in low- voltage apparatus. In appa-
xatua built for conditions of limited space, as railway motors, a higher rise
of temperature must be allowed.
292. d. Apparatus for iNTBRMrrrsNT Sbrvicb. In the case of appa-
ratoi intended for intermittent service, except railway motors, the iemper-
atnre elevation which is attained at the end of the period eorresponaing
to the term of rated load, should not exceed the values specified for machines
in general. In such apparatus the temperature elevation, including rail-
vav motors, should be measured after operation, under as nearly as pos-
siUe the conditions of service for which the apparatus is intended, and
the conditions of the test should be specified.
H. OVERLOAD CAPACITIES.
293. Pbrporiiancb wrni Ovrrload. All apparatus should be able to
mzTf the overload hereinafter specified without serious injury by heating,
spatyng. mechanical weakness, etc., and with an additional temperature
riM not exceeding 15^0., above those specified for rated loads, the over-
load bring applied after the ai>paratus has acquired the temperature corre-
■pooding to rated load continuous operation. Rheostats to which no
temperature rise limits are attached are naturally exempt from this addi-
tional temperature rise of 15*' C. under overload spedfiea in these rules.
294. NoBMAJU Conditions. Overload guarantees should refer to normal
eoDditions of operation regarding s[>eed, frequency,- voltage, etc., and to
non-inductive conditions in alternating apparatus, except where a phase
displaeement is inherent in the apparatus.
295. Otsrix>ad CAPAcrrnui RB(x>iiiUNOBD. The following overload
capacities are recommended:
296. a. Grnvrators. Direct-current generators and altenutting-current
lenentors, 25 per cent for two hours.
297. b. Motors. Direct-current motors, induction motors and synchron-
ous motors, not including railway and other motors intended for intermittent
serviee. 25 per cent for two hours, and 50 per cent for one minute.
298. e. CoNVBRTBRii. Synchronous converters. 26 per cent for two
houn, 50 per cent for one-half hour.
299. d. Tranbforicsrs and Rectifiers. Constant-potential trans-
formers and rectifiers, 25 per cent for two hours; except in transformers
eoDoected to apparatus for which a different overload is guaranteed, in
which case the same guarantees shall apply for the transformers as for the
spparatus connected thereto.
300. e. ExcTTBRS. Exciters ol alternators and other ssrnchronous
msdunes. 10 per cent mote overload than is required for the excitation of
the synchronous machine at its guaranteed overload, and for the same
period of time. All exciters of alternating-current, single-phase, or polyphase
generators should be able to give at its rated speed sufficient voltage and
current to excite the alternator, at the rated sp^sd, to the full-load terminal
^Itage, at the rated output in Idlovolt-amperes and with 50 per cent power
factor.
301. /. A Continuous-Service Rheostat, such as an armature- or field-
[esuiating rheostat, should be capable of carrying without injury for two
ooan, a current 25 per cent greater than that at which it is rated. It
snoald abo be capable of carrying for one minute a current 50 per cent
P^ter than its rated loa^^ current, without injury. This excess of capacity
u intended for testing purposes only, and this margin of capacity should
not be relied upon in the selection of the rheostat.
302. 0- An Intermittent Service or Motor-starting Rheostat is used for
9^ing a motor from rest and accelerating it to rated speed. Under
ordinary conditions of service, and unless expressly stated otherwise, a
motor is assumed to start in fifteen seconds and with 150 per cent of rated
current strength. A motor^tarter should be capable of starting the motor
under these conditions once every four minutes for one hour.
$^:
522 STANDARDIZATION RULES.
808. (a) This Test may be earned out either by startins the motor al
four-minute intervals, or by placing the starter at normal tempeiattire metom
the maximum voltage for which it is marked, and movins the lever uai*
formly and gradually from the firat to the last position during st period
of fifteen seconds, the current being maintained substantially constant aA
said 50 per oent ezoess by introducing resistanoe in series or by other suateUl
means.
304. (b) Other Rheostats for Intermittent-Service are employed undsr
such special and varied conditions, that no general rules are appUeatde t»
them.
A. VOLTAGES.
805. DiBXCT-CuRiOBNT Gbnsratoiui. In direet-ourrent, Iow^volta0i
generators, the following average terminal voltages are in general use and
are recommended:
125 volts. 250 volts. 550 to 800 i^ts.
306. Low-Voi^TAGB CiBcnrrs. In direct-current and alternating-cur-
rent, low-voltage circuits, the following average terminal voltages are la
gencMral use ana are recommended:
110 volts. 220 volts.
307. Pbiuart Distribution Circuitb. In alternating-current, eon-
stant-potendal, primary-distribution circuits, an averafce voltage of 2.200
volts, with Btep^own* transformer ratios ^ and #«. is in general uae. and
is recommended.
308. Tranbiiisbion CiRCurrs. In alternating-current, constant-poten-
tial, transmission circuits, the following average voltages are reoommendedi
6,600 11.000 22.000 33.000 44.000 66.000 88,000.
300. Transporicbr Ratio. It is recommended that the standard
tran^ormer ratios should be such as to transform between the standard
voltages above named. The ratio will, therefore, usually be an exact mul-
tiple of 5 or 10. e^., 2.200 to 11.000: 2,200 to 44,000.
310. Rangb in Voltaob. In alternating-current geneoratora, or gen*
crating ssrstems, a range of terminal voltage should be provided from rated
voltage at no load to 10 per cent in excess thereof, to cover drop in trans-
mission. If a neater range than ten per oent is specified, the cenerator
should be considered as special.
B. FREQUENCIES.
311. In Altemating-Ourrent Circuits, the following frequeneieB are
standard:
26^^ 60^
312. These frequencies are alreadv in extensive use and it is deemed
advisable to adhere to them as closely as possible.
TV, AKlfBRiAX. llKCOMmiBirDATIOMft.
313. Namb Platbs. All electrical apparatus should be provided with
a name plate giving the manufacturer's name, the voltage and the current
in amperes for which it is designed. Where practicable, the kilowatt
oaiMtcity, character of current, speed, frequency, type, designation and
serial number should be added.
314. DiAORAMs or Connbctionb. All electrical aoparatus when leav-
ing the factory should be accompanied by a diagram snowing the electrical
connections and the relation of the difFraent parts in sufficient detail to pve
the necessary information for proper installation.
APPENDICES AND TABULAR DATA. 623
WHBm RsBOSTAT Data. Eyery rheottot ■hoiild b« daarhr and p«m»-
MBftfar marked with the voltac^ *nd amperai, or rence of amperee, for
vSb H k deeicned
8M. CbiiOUD Imdicatino Liqhtb. When ueins eo|ored indioetiiur
danger ■uoh at "switch eloeed.
<Mk switehboards, red should denote
"eirouii alive"; green should denote safety, such as '^switoh open," or
areait ilead.*'
317. When white lights are used a light turned on should denote danger.
a« ''switch dosed" or "circuit alive"; while the light out should
denote safety, such as "switch open," or "circuit dead." liow-efficiency
faonpa should be used.
31S. The use of colored li|hts is wwommended as safer than white lii^te.
319. OnoTncDOfo Mbtal Work. It is desirable that all metal work
Bear hii^potential drouits be grounded.
320. CmcuR Ofbnino Dbvicbs. The following definitions are reoom*
I mended:
[ 321. a. A Greuit Breaker is an apparatus for breaking a drcuit at the
huAMst current which it may be called upon to carry.
322. b. A Disconnecting Switch is an apparatus designed to open a
dremt only wbuk carrying little or no current.
333. c An Automatic Circuit Breaker is an M>paratus for breaking a
dreoit automatically under an excesdve strength of current. It should
be capable of breann^ the drcuit repeatedly at rated voltacB *nd at the
meTJmnnfc current which it may be called upon to carry.
APPENDIX A. NOTATION.
The following notation is recommended:
B, «, voltage, EJf .F., potential difference.
^ i, current.
P^ power.
#. magnetic flux,
ffi, Bt magnetic dendty.
s. re
SS, s, impedance.
L, I. inouotance.
C, c capacity.
x . y, admittance.
ft, susceptance.
0» Ot conductance.
Veetor quantities when oaed should be denoted by capital itaUcs.
APPENDIX B. RAILWAY MOTORS.
0) RaHng.
325. Imtboduciort Nois on Ratino. Railway moton araally
MMtate in a service in which both the speed and the torque developed by
tM motcv are varying almost contintuUly. The average requirements,
htfweteM, during succcMive houn in a given dass of service are fairly uni*
Ibnn. On accoont of the wide variation of the instantaneous loads, it is
inqpraeticable to asdcn any simple and definite rating to a motor which
wifl Indicate aeeuratciy the absolute capadty^ of a given motor or the rda-
thre eapadty of different motors under service conditions. It is also im*
pffaeUcable to select a motor for a particular service without much fuller
data with regard both to the motor and to the service than is required, for
eoaaiple, in the case of stationary motors which run at constant speeds.
33n. SoopB or NoiinrAL Ratino. It is common usage to give railway
moton a nominal rating in horee^power on the basis ot a one>hour test.
As above explained, a dmple rating of this kind is not a proper measure of
service o^Muaty. This nominal rating, however, indicates approximatdy
the amximam output which the motor should ordinarily be called upon
to develop during aooderation. Methods of determining the continuous
eraadty o(f a railway motor for service requirements are given under a
wineeqnent luMdingi
524 STANDARDIZATION RULES.
827. The Nominal Rating of a railway motor is th« borse-poi
at the car-axle, that is, including gear and other tranamiaBion loi
gives a rise of temperature above the surrounding air (referred to a.
temperature of 25° C.) not exceeding 90° C. at tlie commutator and. '
at any other part after one hour's continuous run at its rated voltAi^e (i
frequency, in the case of an alternating-current mot<Mr) on a stax
the motor-covers removed, and with natural ventilation. The
temperature is to be determined bv thermometer, but the resistance
electrical circuit in the motor shall increase more than 40 per cent di
the test.
(II) BdeeHon of Motor for Specified Sernce.
328. Genbral Rxquirsmsntb. The suitability of a railway motor
a specified service depends upon the following considerations:
329. a. Mechanical ability to develop the requisite torque and
as given by its speed-torque curve.
330. 6. Ability to commutate successfully the current demanded.
331. c. Ability to operate in service witnout occasioning a tempera tun
rise in any part which will endanger the life of the insulation.
832. Ofbbatino CoMorrioNS, Typical Run. The operating oondxtioiis
which are important in the selection of a motor include the wei^t of lottd,
the schedule speed, the distance between stops, the duration costope, tlie
rate of acceleration and of braking retardation, the ^prades and the curves.
With these data at hand, the outputs which are requued of the motor may
be determined, provided the service requirements are within the limits «
the speefl-torque curve of' the motor. These outputs may be expressed
in the form of curves giving the instantaneous values of current and of
voltage which must be appued to the motor. Such curves truky be laid
out for the entire line, but they are usually constructed only for a oertaia
average or typical run, which is fairly representative of the conditions of
service. To determine whether the motor has sufficient capacity to per-
form the service safely, further tests or investigations must be made.
333. Capacity Test of Railway Motor ik Servicb. 'Hie capacitv ol
a railway motor to deliver the necessary output may be determinea by
measurement of its temperature after it has reached a maximum in service.
If a running test cannot be made under the actual conditions of service, aa
equivalent test may be made in a typical run back and forth, under aueh
conditions of schedule speed, length of run, rate of acceleration, etc., that
the test cycle of motor losses ana conditions of ventilation are cnsentUdly
the same as would be obtained in the specified service.
334. Methods of Comparing Motor Capactft wrrn Service Rbquibs-
MENTS. Where it is not convenient to test motors under actual service
conditions or in an equivalent typical run, recourse may be had to one of
the two following metnods of determining temperature rise now in general
use:
33.5. 1. METHOf) BY LosABS AMD Thermal Capactty CuRvm. The heat
developed in a railway motor in carried partly by conduction throuia^ the
several parts and partly by convection throu^ the air to the motor^rame
whence it is distributed to the outside air. As the temperature of the
several parts is thus dependent, not only upon their own internal ki^«s
but also upon the temperature of neighboring parts, it becxnnes necessary
to determine accurately the actual value and distribution ci loeses in a
railway motor for a given service and reproduce than in an equivalent
test run. The results of a series of typical runs expressed in the form of
thermal capacity curves will give the relation between degrees rise per watt
loss in the armature and in the field for all ratios of looses between them
met with in the commercial application of a given motor.
336. This method consists, tiierefore, in calculating the several internal
motor losses in a specified serWce and determining the temperature rise
with these lossies from thermal capacitv curves giving the degrees rise
per watt loss as obtained in experimental track tests made under the same
conditions of ventilation.
337. The following motor losses cause its heating and should be oarefully
determined for a given service: PR in the field; PR in the armature; PR in
the brush contacts, core loss and brush friction.
338. The loss in the bearines (in the case <^ geared motors) also adds
APPBNDICJBS AND TABULAR DATA. 526
to the motor heating, but owin^ to the variable nature of such
they are seaeraily Delected in making oalculations.
(C 2. Kbthoo bt Continuous CAPAcrrr or Moior. The essential
in the motor, as found in the tjrpical run, are in most cases those in
Kiiotor windinei and in the core. The mean service conditions may be
rvssed in terms of the current which would produce the same losses
Lbe motor windings and the voltage which, with that current, would
luce the same core losses as the average in service. The continuous
icseuaty of the motor ia given in terms of the amperes which it will ccury
wsrl^jeai run on a testing stand — with covers on or ofiF, as specified — at
cftxfiTcvQnt voltages, say, 40. 60. SO and 100 per cent of the rated voltage —
wi^c^ a tonperature rise not exceeding 90 degrees at the commutator and
'7^> ^i^jees at any other part, provided the resistanoe of no eleotrie circuit
\ta. "the motor increases mora than 40 per cent. A oomparison of the equivar-
Icnat service conditions with the continuous eapaqitjr of the motor will
d^^ermine whether the service requirements are within the safe capacity
43C the motor.
340. Tbia method affords a ready means of determining whether a speci-
fied service ia within the capacity of a given motor and it is also a
oonvenient approximate method xor comparing the service capacities of
<liflerent motora.
APPENDIX C. PHOTOMETRY AND LAMPS.
Ml. Caitdlb-Powbr. The luminous intensity of sources of li^t is
expressed in candle-power. The unit of candle-power should be derived
ffram the standards maintained by the National Bureau of Standards at
'Washington. D. C. whjoh standard unit of- candle-power equals W of
Honer.
the Heiner unit under Reiohsanstalt standard conditions for the
In pcaotioal measurements seasoned and carefully standardised incan-
deseent lamps are more reliable and accurate than the primary standard.
342. GAN]>i.ii>-Lcna!N. The total flux of light from a source is eaual to
its mean spherical intensity multiplied by 4 r. The unit of flux is called the
candle-IumeD. A candle-lumen is the .— part of the total flux of light
emitted by a source having a mean spherical intensity of one candle-power.
343. Candij&-Mbtbr. The unit of illumination is the candle-meter.
This is the normal Ulumination produced by one unit of candle-power at a
distance of one meter.
344. a. Candlb-Foot. Illumination is occasionally expressed in candle-
feet. A candle-foot is the normal illumination produced by one unit of
amdle-power at a distance of one foot.
345. 1 candle-foot » 10.764 candle-meters.
The use of the candle-meter unit is preferable and is recommended.
346. The Efficiency of Electric I^mps is properlv stated in terms of mean
sdberieal candle-power per watt at lamp terminals. This use of the term
efficiency is to be considered aa special, and not to be confused with the
generally accepted definition of efliciency in Sec. f>5.
347. a. Eppicienct, AtrxiLtAKY Dbvicks. In illuminants requiring
auxiliary powernsonsuming devices outside of the luminous body, such as
steadying resistances in constant potential arc lamps, a distinction should
be made between the net efficiency of the luminous source and the gross
efficiency of the lamp. This dutmction should alwasrs be stated. The
gross efficiency should include the power consumed in the auxiliary resis-
tance, etc. The net efficiency should, however, include the power con-
sumed in the controlling mechanum of the lamp itself. Comparison between
such sources of light should be made on the basis of_ gross efficiency, since
the power consumed in the auxiliary device is essential to the operation.
3W. b. A Standard Circuit Voltage of 110 volts, or a multiple thereof,
may be assumed, except where expressly stated otherwise.
349. Watth pbr Candle. The specific consumption of an electric lamp
a its ^WEtt consumption per mean spherical candle-power. "Watts per
candle" is the term used commercially in connection with incandescent
lamps, and denotes watts per mean horizontal candle-power.
350. Fbotometric Tests in which the results are stated in candle-power
should always be made at such a distance from the source of light that
i
526
STANDARDIZATION RULES.
the
the Utter may be regarded aa practically a point. Where teste are
at shorter distances, as, for example, in the measurement of lamps
reBeotora. the results should always be given as "apparent candle-poi —
at the distance employed, which distance should alwasrs be epeoificsalljr
stated.
361. Basis bob Comparibon. Either the total flux of U^t in
lumens, or the mean spherical candle-power, should always be used
basis for comparing various luminous sources with each other, unler
is a dear underatanding or statement to the contrary.
352. iNCANDaacBNT Lamps, Rating. It is customary to rate
descent lamps on the basis of their mean horisontal candle-power; but ia
comparing incandescent lamps in which the i-dative distribution of Ittm^
inous intensity diflFers, the comparison should be based on their total finz
of li^t measured in lumens, or on their mean spherical oandla-power.
3^ The Spherical Reduction-Factor of a lamp
mean spherical candle-power
mean horisontal candle-power
354. The Total Flux of light in candle-lumens emitted by a lamp »
4 V X mean horisontal candle-power X spherical reduction-factor.
355. The Spherical Reduction-Factor should only be used when properly
detennined for the particular type and characteristics of each lamp. The
spherical reductioiwactor permits of substantially accurate oompaxiaoiis
being made between the mean spherical candle-powers of different ty|>es
of incandescent lamps, and may be used in the absence of proper facdtties
for direct measurement of mean spherical intensity.
356. "Rsading Distancb." Where standard photometric nifeasiire-
ments are impracticable, approximate measurements of illuminants. sudi
as street lamps, may be made by comparing their " reading distances: t ^^
by determining alternately the distances at whidi an ordinary siae of read-
ing print can just be read by the same person or persons, whca all other
liipit is screened. The angle bdow the horisontal at which the measure-
ment is made should be specified when it exceeds 15^.
357. In Comparing Different Luminous Sources not only should their
candle-power be compared, but also their relative form, intrmsie brilliancy,
distribution of illumination and character of li^t.
^
APPENDIX D. SPARKING DISTANCES.
858. Table of Sparking Distances in Air between Oppoeed Sharp Needle-
Points, for Various Effective Sinusoidal Voltages, in inches and in oenti-
meters. The table applies to the conditions specified in Sees. 246-240.
359.
Kilovolts
Distance.
lOlovolts
Distance.
Sq. Root of
Sq. Root of
Mean Square.
Inches.
Cms.
Mean Square.
Inches. Cms.
5
. . 0.225
0.57
140
. . 13.05 35.4
10
. . 0.47
1.19
160
. . 15.0 38.1
16
. . 0.725
1.84
160
. . 16.05 40.7
20
. . 1.0
2.54
170
. . 17.10 43.4
25
. . 1,3
3.3
180
. . 18.15 46. 1
30
. . 1.625
4.1
190
. . 19.20 48.8
35
. . 2.0
5.1
200
. . 20.25 51.4
40
. . 2.45
6.2
210
. . 21.30 54.1
45
. . 2.95
7.5
220
. . 22.35 56.8
50
. . 3.55
9.0
230
. . 23.40 50.4
60
. . 4.65
11.8
240
. . 24.45 62.1
70
. . 5.85
14.9
250
. . 26.50 64.7
80
. . 7.1
18.0
260
. . 26.50 67.3
90
. . 8.35
21.2
270
. . 27.50 60.8
100
. . 9.6
24.4
280
. . 28.50 72.4
110
. . 10.75
27.3
290
. . 29.60 74.9
120
. . 11.85
30.1
300
. . 30.60 77.4
130
. . 12.90
32.8
1 ii-
APPENDICES AND TABULAR DATA.
527
APPENDIX E. TEMPERATURE CX>EFFIGIENTS.
300. Table of Temperature Coefficients of Resistivity
DiJIneDt Initial TemperatureB Centigrade.
in Copper at
Initial
Temperature
Cent.
Temp.
Coeffiaent
in per oent per
degree Cent.
Initial
Teoiperature
Cent.
Temp.
Coefficient
in per cent per
degree Cent.
0. .
. . 0.4200
26
27
0.3786
1. .
. . 0.4182
0.3772
2. .
. . 0.4165
28
29
0.3758
3. .
. . 0.4148
0.3744
4. .
. . 0.4131
30
31
32
0.3730
5. .
. . 0.4114
0.3716
6. .
. . 0.4097
0.3702
7. .
. . 0.4080
33
34
35
0.3689
8. .
. . 0.4063
0.3675
9. .
. . 0.4047
0.3662
10. .
11. .
. . 0.4031
. . 0.4015
36
37
38
0.3648
0.3635
12. .
. . 0.3999
0.3622
13. .
. . 0.8983
39
40
41
0.3609
14. .
. . 0.3967
0.3596
15. .
. . 0.3951
0.3583
16. .
17. .
18. .
. . 0.3936
. . 0.3920
. . 0.3905
42
43
44
0.3570
0.3557
0.3545
19. .
20. .
21. .
. . 0.3S90
. . 0.3875
. . 0.3860
45
46
47
0.3532
0.3520
0.3508
22. .
23. .
24. .
. . 0.3845
0.3830
. . 0.3815
48
49
50
0.8495
0.4383
0.3471
25. .
. . 0.3801
•
The fundamental relation between the increase of resistance in copper
and the liae of temperature may be taken as
JJ, - fi, (1 + 0.0042 0
where R^ b the resistance at f* C. (rf the copper conductor at 0** C. and Rt
is the corresponding resistance. This is equivalent to taking a tempera-
ture coefficient of 0.42 per oent per degree C. temperature rise above 0° C
For initial temperatures other than (rC, a similar formula may be used
■ubstituting the coefficients in the above table corresponding to the actual
initial temperature. The formula thus becomes at 2o^ C,
0.3801
-«i(
1 +
-0
*+»• "*V ' 100
where ff| is the initial resistance at 25** C, Rf^^ the final resistance and
r the temperature rise above 25** C.
In order to find the tonperature rise in degrees C. from the initial
rarietanoe R^ at the initial temperature i? C. and toe final resistance Ri^ we
nay use the f oxmula
See See. 266.
r - (238.1 + 0 (-^ -1 ) degrees G.
^
y
ELECTRIC LIGHTING.
RsvisxD BY Dr. C. H. Sharp..
VxLociTT of light 300,000 kilometers per second, or 186,000 miles per
•eoond.
CompoAltlom of Sanlls'lit.
Violet produces the maximum chemical effect.
Indigo. Blue. Green.
Yellow, the maximum light effect.
Orange.
Red produces the maximum heat effect.
The most luminous part of the spectrum is the yellowish green.
Colors.
Prlmarj. Red. Yellow. Blue.
Orange. Purple. Green.
I.AWS of SadlatioB of » Black Body
SUfan-BoUzmann law. The total energy radiated by a black body is
proportional to the fourth power of its absolute temperature.
S - a9*.
Wien's displacement law. The product of the wave-length of the max-
imum of radiation and the absolute temperature of the radiating body is a
constant.
Aw0= const. •■ A.
The quotient of the maximum radiation by the fifth power of the abso-
lute temperature is a constant.
Bm»-^ = const. = B.
Applsring these laws the temperature of radiating bodies can be det^r*
mined with a degree of accuracy which depends chiefly on the degree to
which the body approaches a black bod^ in its characteristics. Luminer
and Pring^heim have found that for polished platinum Am9 « 2630. while
for a black body Am0 = 2940. Hence the temperatures of other radiating
bodies such as carbon must lie between the limits set by the two equations
^ 2630 , ^ 2940
e oa — — and B = — - — •
Am Am
Tlio lDt«iiMit^ of a ftonrco of light is measured by comparison with
source of unit mten.sity. The unit of luminous intensity commonly
tiployed is the candle- potter.
ufensttj of UlamlnatfOB produced on a surface by a source
i light concentrated at a point is inversely as the square of the distance
oetween the surface and the source of light,
- ^ .^ - ... . ^. Intensity of source ^
Intensity of illumination = rr— z X ooe t,
diatance*
where t is the angle of incidence of the rays.
Units of illumination are the foot-candle and the meter-candle or candle
lumen (A. I. E. E.) The foot-candle \h the illumination produced on the
surface one foot distant by a source of one candle-power, the rays falling
normally on the surface.
628
1
LIGHT.
529
Tlie meter-candle or candle lumen is similarly defined, the meter being
substituted for the fooC
The unit of iBBSlaove llax is defined as follows : A unit flux is that flux
smt by a sooroe of unit intAwity (eandie-power) through a ui^ selid angle.
Thb unit is csgdled the lumen or oaodle lumen (standardisation rules of
A. I. E. E.) From a source of 1 o.p. the total flux is 4 x lumens. The
symbol for flux is ^.
Flux and mtenatty of illumination are connected by the following relation:
Illumination *
Flux
Surface
or B
-i.
iS
Mean horizontal intensity is the average intensity in all directions in the
horisontal plane passing through the source. In case of an incandescent
lanip this plane is taken perpendicular to the axis of the lamp.
Mean spherical candle-power is the average candle-power in all directions
in space. It bears the following relation to the total luminous flux from
the source,
4 ir
Mean hemispherical candle-power is defined as the average candle-power
in an directions in a hemisphere having the source of light at its center.
The spherical reduction tactor is the ratio of the mean spherical candle-
power to the mean horizontal candle-power.
Trotter gives in the following table the intrinsic brightness of different
sonrees of Hgfat.
I of Dlllerciit fto«roe« of JLIgrbt.
(Trotter.)
Platinum (Violle standard) . . .
Sun's disk
Skjr, near sun
AIdo carbon on edge
White paper, horisontal, exposed to
minuner sky, noon
White paper, sun 60^ high, paper fac-
ing sun
Albo carbon, flat
Argand
Bliiuck velvet, summer sky, noon . .
White paper, reading without strain-
ing V. . .
C.P. per Sq. In.
Red.
120
487.000
120
73.6
ie.5
8.25
10.5
6.8
0.0333
0.0018
Green.
120
1,000,000
120
00.7
35.2
17.
8.
5.
2
7
29
0.07
0.0024
C.P. per Sq. Cm.
Red.
18.5
75.500
18.5
11.4
2.56
1.28
1.63
1.05
0.0052
0.00028
Green.
18.5
155.000
18.5
9.4
5.45
2.67
1.35
0.82
0.0109
0.00037
8penn candle
Moon, 35° above horlzoa
Mcjon, high
Batswing (whole flame)
Methren standard
Incandescent carbon filament (glow lamp)
Crtter of electric arc
White.
2
2
8
2.
4.
120
45,000
26
3
White.
0.31
0.31
0.46
0..36
0.666
18.5
7,000
fiSO EL&CTBIC UGBTINQ.
Vmm Bad ■*•>«•(«■ 1 U^t.
Tks iBMaa)^ vf <» «»■»•« b sf I.lrk« ia »iipnw«d in tomi rf '■
thai o( (ome apedfisd unit or ■tamUrd of rrfwenoe.
No very wtWioiom aUnitonl for nil purpowa hu u r^ b«B prndoKd,
but thoM liitsd below an uaoai the bat in laa or propoaad.
a. rJw AnfuA Mandarrf candU, a a| ^ ..-i.
Tbb lurin, (Aich ia soa cl
- D atandanM. ia abowti in FifL
tbafoim Inwhiib it ia opuatraetad H
EUDater. mlffainc one-aiith pound, and butoiu at iha ntia of
r hour. In aaaa th( rMa ul bunuiw of t&e candle doaa
equal 130 Buina p«r hour but falla vilUn the UniM of 114 to 13B paia*
par haar, tCa value td tha ll«tat ia to be detarmiued by aimj^ rai^ioRiiM
aaauDiinc tliat tbe intenalty of tbe oandle Udit vaiias in praporHoD to iha
mte of eonaumptliui tt apenn. Tfaia atandard, in apita of manjr drfaiN^
ia ((Ul in eitanaive ua* and ia kcaliKi in many — — '• — "-
(uniiaiUB tha unit of mcHunaneot in thia oountry.
t. Hareaurt 10 doikU* panlona tbmiard. Tbia lamp,
tb* bwt of niDdem atandaida.
landSi
theAmi
Boaed of • mlxtnra of pantane vapor and air.
The poitane ia a H^t dIalillaUof pelrolan
paaainc ovar at a tamparatara baiwaan 35* ui
W° C. TIh pentane ia oontaiDad in tha tbikx-
iaer at tha lop of the lamp, from wUoli it baa
by ila own wii^t down uuoush tha amaD tuba
to the liaae <jI an Arsand l>umar. irtict« itr«>ma
a flame iuaide a metal ehimiMy. The baae d
the diimnay ia acljuatad aoeuialdy to a bcafht
of 47 mm. above the top of tlw buniB. and ll
ia only tlie portion rf the flame wfaiob ooma be-
heifht by obaerviuit tl
in tha diimnay. Tb* expoaad poHion d tha
flame ia pcoteoted fmn dimuchta l>y a eoojaal
ahield ofxn on ona rida. Tha lamp ahonld ba
used in a wcil-vwUIatwl room free 7ran anid-
abla draujrfita. Aoeordlna (o PaMnoo of tha
National Phyalcal Labamtorr the eandle^xiw
of the lamp ■ expnaaed by (he equaticia:
op. - 10 + o.oae (10 - •) - oiwe {7« -«.
- DndlUon
e. Tha Carrd lamp, tha prineipafFrw
of purified oolia oU par hour, the Suae bejna 40 mm. hixfa. Hit. RmbhiIi
and DuDiaa bava proven by experimenla that whan uia conaumption of
ooLaa ia al a rata batwean 40 and 44 (rami par hour, tha liiiit emitted br
thia atandard is propDitional to the wscht o( colia burned. FoUowiag ■
a lalile ahowini the proper dimcoiatoaB oT (iua a(andan]-
(]
582
ELECTBIC UGHTING.
Dimeoaions of Garoel Lamp.
External diameter of burner
Interior diameter of inner air current . . .
Interior diameter of outer air current . . .
Total heiglit of chimney
Distance from elbow to base of ^ass . . .
Exterior diameter at level of bend ....
Interior diameter of glaos at top of chimney
Mean thickness of glass
23.5
17.0
45.5
290
61
47
34
2
J^
Use Ufldithou9e wick weii^ng 3.6 grama per decimeter and woven with
75 Rtrancb. This standard is quite satLsfactorv if carefuUv used.
d. The platinum atandard proposed by Violle is the light emitted by one
square centimeter of platinum at its melting-point. Violle shows that tlie
light emitted by this unit is equivalent to 19^ to 191 British candles. This
standard haa never been reduced to practice. The French bougie ^<4Wmi^
is supposed to equal the 20th part of the Violle platinum unit.
6. nefner Amyl Lamp. The legal standard in Germany is the so-called
Hefner unit, which is the light given by the Hefner-Alteneck amylacetate
lamp. This lamp haa been exhaustively investigated by the Rdcfaauutalt,
which certifies to the aoeuracy of lamps submitted to it; its Intensity is about
10 per cent less than that of the English candle, and ita nonnal flame is 40
millimeters high. It is very uniform and reproducible, and owing to the
fact that lamps of certified value can be so readily obtained it ia widely used,
not only in Germany, but ebewhere. Careful inatructiona are issued with
each lamp, and when used in accordance with these instructions the errors of
measurement are not more than half those met with in the use oi standard
candles. The color is somewhat against this unit, being a distinctly reddish
orange, which ia a, rather aerioua objection when used as a working standard
in measurements 'of Webbach burners or incandescent and Nemst lamps.
Even with its faults though, it is probably the best primary standaitl tokt
we have, as it can be reproduced accurately to a most unusual desree.
This lamp has of late come into very general use as a reliable, moderate-
priced and eaaly reprodudble standara. It has been reconmiended by
the American Institute of Electrical Engi-
neers and the German Rachaanstalt.
A cylindrical base contains the amvl acetate,
which is drawn up through a wick tube of Gei^
man silver in a specially prepared wick. The
height of this German silver tube and the
height of the flame are of vital importance.
To secure the proper adjustment at the time
the lamp is used, an optical flame gauge b
provided, consistmg of a small camera with
lens, and ground glus plate. On this ground
glass plate a horisontal line determines exactly
the point at which the top of the flame should
be kept. An error of 0.2 oi a millimeter is
the height of the flame produces an error of
^ of 1 per cent in the candle-power, so their
setting must be made closely.
In using this lamp special care should be
taken that fresh air m abundance is supplied,
but the room must be perfectly free from
draughts or air currents, and it should be
watched by a person at a distance from it.
If the flame does not bum steadily the wick
should be carefully trimmed, making itsome-
what crowned. Never char the wick bjf
burning it too high; after continued use it
Fio. 8* should appear to be only sli^tly browned.
LIGHT.
533
With & httle experiMioe it will be found that the flame can be kept accur-
ately on the line of the optical flame gauoe and quite steady. The variatioiu
at temperature, humidity and barometerneicht affect the candle-power of the
M 40 (0 CO 70 so
CHANGE IN INTENSITY FROM HUMIDITY
AT MPPERENT TEMPERATURES
Fro. 4.
lamp to a certain extent, but these fluctuations have been investigated fully,
and oorrections are given in the accompanying diagrams (Figs. 4 and 5).
600 ttO MO CM TOO 76b 80O 860 MO
CHANQC IN INTENSITY WITH BAROMETER HEIGHT
FlQ. 6.
It lAmpa SM S«coB€lary Atandarda. Carbon fila-
ment lamps which have been seasoned by burning them a few hours until
their initxai period of rise of candle-power at constant voltage has been
pasaed, furnish secondary standards of light of remarkable constancy. It
should be understood, however, that no single lamp can be relied on abso-
lutely, but rather the average value ip ven by a group of such lam ps . The uni-
formity of results which is obtained in the photometry of incandescent lamps
in prea«it practice in this country ia due in no small measure to the fact that
incandescent lamp standards, practically all of which emanate from the same
laboratory, are in nearly universal use. These sub-standards have been
etandardixed not by direct reference to a primary standard, none of which
is entirely constant, but by reference to>a eerier of incandescent lamp secon-
dary standards, whereby a constant value for the unit is obtained. An
invariable unit of himinous intensity has been maintained by such a series
of lamps by the Electrical Testing Laboratories in New York for upwards
of ten years. The standardisation value for these lamps was derived from
a nmilar series in the possession of the Edison I^mp Works, which were
in turn standardised originally by reference to lamps standardized in the
Reichaanetalt. The basis of this original standardization was the assump-
tion that the Hefner unit equals 0.88 candle-power. This ratio has since
received the saoetion of the A. I. E. E.,and more recently the Bureau of
Standards in Waahhigton has established its unit of luminous intensity
(
534
BLECTBIC UGHTING.
OB Uie nine baois. Thus it has oome about that photometrie
ments in thia country which are nominally based on the British nandly
a unit are actually, as far as electrical measurements are oonoemed, '
on an invariable unit representing one of the yalues which the vi
candle may assume, which is maintained by standardised inc&ndc
lamps, ana which is reproducible only throng the intermediary td_ihm
Hefner standard lamp. Standardised lamps are furnished by the
trical Testins Laboratories in New York of any required candle-powei
voltage and for use either stationary or rotating. A special type of
has been devdoped for use in making stationary standards. Tneae lamna
have two horM-shoe shaped filaments in the same plane, one inaide taa
other. The standard direction in these lamps is at right angiea to tte
plane of the filaments, as indicated by vertiml lines etched in the ^aaa.
Lunps are also standardised and certified by the Bureau of StandAras.
On account of the adoption of the Harcourt 10 candle pentane lamp
as the official standard by the Metropolitan Board of Gas Referees of Ixmdoa
and the introduction of this standard into practice in this country, diiefly
in the photometry of illuminating gas. a discrepancy has aiiseii between
the candle of the electric industry and the candle of the gsa industry.
Recent international determinations of the ratio between the Hefner unit
and the pentane unit, have shown that the Hefner equals 0.915 candle-power,
the candle being defined as the one-tenth part of the intensity of the
pmtane unit. As has been said, the value of the Hefner in terms of the
candle of the dectrical industry and of tibe Bureau of Standards is 0^.
The matter of this discrepancy i» now (Dec., 1907) under advisement by
a joint committee cNf the Illuminating Engineering Society, the Ameriean
Institute of Electrical Engineers, and the American Gas Institute.
The following is a table giyinff the values of the various standards and
units in terms of each other. This table is compiled from the most reoent
data on the subject.
<
•
m
m
h9
H
^
•
0* .
O
1
^1
25
•
II
■
1
1
UnitN
Londoi
Hefner unit
1
0.0915
0.093
• • ■
0.88
• • ■
• • •
10 c.p. pentane
10.95
1
1.02
• • •
• • •
• • •
• ■ •
Oircel
10.75
0.980
1
9.6
• ■ •
* ■ • •
» ■ •
Bousie dMmale
Oandie unit. U. S. A. . .
• ■ •
0.1042
1
• • ■
• tt •
• « ■
■ • •
■ • •
1
1.018
1.090
Unit National Physical Lab-
oratory. London . . .
• • •
• • •
• • •
• ■ •
0.984
m • •
• • •
Unit Laboratoire Central
d'Eltetridt^. Paris . .
• • ■
« • •
• • •
■ • •
0.982
• mm
• ■ •
/
A photometer is an apparatus for measuring the intensity of a source cf
H|^t or ot an illuminatton in terms of a standard. In case the apparatot
is intended for the latter purpose only, it is sometimes called an illmni-
nometer." All photometric measurements are made by a visual oompar>
ison of the source to be measured with some standani. The eye oannoi
tell us how many times brighter one liriit is than anothw. It can say
only that one illuminated field is just as bright as another. A photometer
consists, then, of two essential parts: first, an arrangement whereby two
fields are obtained in juxtaposition to each other, one of them being Uliimi-
PHOTOHSTEBS. 635
-„ 'IhaUshlwUthbtobciiL ,
wbrntar tlM b^tnaw of onaor both tht 6Mm
- b* sompuud ■■ (ODa u tbi
tha bilda ua hukI Id Uluml
must bt prevldwl; nunily.
liaUkin wCU i* to be nwui
■ whi«h I* bmM oomaraalr •mplcmd is
a from a pwiMitoEiii ■outdo of lint vuli
rtooM to UM aoani. A eominoa Tons o( ,
in Re. 4. Tho bsht to bo mmmand ood tba ntuiduil Ugbt
oppoiiM aodi <!< a bar oo wfalob tlu daht4>ox oontainitic a
laiiMi or diak tor taatinc tha aquaBtr oT iUumlnktioa naa b«
novad. Wban ■ Mttinc ha* ba«i mada. (ha
Flo. 8. PbotonMar, Quam 4 <7o.
at H(ht aia dlraatlr proiiortioDal to tba aqiura cf their nipaotiTa diataoaaa
hoB tba pbotomatrie aoraan Id tba riaht-boi,
Tba fonu of liaht-box *hiah an moat oouunonlr tinplojiad ara tha
n and tba Lnmma^Bnidhuii. Tlia Utiar ia uoeioelled by ^nv nthw
tAotamalria davica irixn tba H^t* to ba oomparad ■» cf tha
Wb«a color diStcaoeaa an triimt, tba Buoaan is ti *^
■Daeiallyaa whaa It la aqulpiiad with tha Lacaon atsr dii-,
lBBHBa*B*apbotomat^apiaeaitf iriutepapar — aartajnkindacf dnochu
(■V papar aia BDod — with a fraaaaapot in ila imlaria plaead betwaao tba
n> tisbta with ila aurfaia at ri^t anclaa to tba nyi. Bahlnd (ba papar
tsD inaaai at limit* iiwar at tba piapar dacna d I
rida piaaaa nar ba pSad faat lo tba middla piaoa.
r
ELBCTBIC UGHTINQ.
536
In the
meter, diagram and cut of the
of which are shown below, the rajm
light from the two souroee under
pariflon enter at the sides so as to
the surfaces of the opaque gypsum »
Diflfused lis^t from these white su
reaches two parallel mirrors (inside)
an angle of 45^, and is reflected to
angled prisms which have the
portions of their hvpothenuse su
cut away and coated with asphalt v
to secure complete absorption. ,
entering the pnsms from the mirrors k'
Lummer> either transmitted or totally reflected at
their surface of contact, so that an ob*
server at the telescope tube sees a ciroB*
lar disk of light from one side of the gypsum screen surrounded by an as*
nular ring- of light from the other side, the boundary line between ttei
two being sharply defined.
Fia.
7. Diagram of
Brodhun Photometer.
Fig. 8. Lummer-Brodhun Photometer Carriage.
/
Rnmford'a photometer compares the shadows of an opaque rod throm
on a white screen by two lights.
When the shadows are of equal density.
5?
In Ritchie's photometer two equal white surfaces are placed at n
ani^e with each otoer, and with the line of light and their bn^tness com-
pared, moving back and forth on the line of light until both surfaces sn
alike in illumination ; the relative intensities of the lights are tben the sszbs
as with the Bunsen instrument.
In JToly'a photometer, two slabs of paraffin wax, or transluooit gjtfi
about 3' X 2*^ X 4', are fastened together back to back by Canada balsun,
a sheet of paper or silver foil being first interposed, after which the edgsi
and surfaces are ground smooth.
This slab is placed between the two lights, with the plane of the joint si
right angles to the line between the lights, and moved back and forth ot
that line until the observer looking at the edge of the slab finds both sidsi
equally illuminated, when the relative intensities are as before. By revere
ing the slab, a check can be had oa the observation.
PHOTOMETERS. 537
• W^m Vefl< JPlaie. — Pnaion 3. MiUar. In geoer»l work the intensity
'rtbe lisht incident upon a given surfaoe is the only quantity which it la
' learoe or even desirable to measure. This is not proportional necea-
to the illuininatinc effect, which varies as well with the point from
the Borfaee is viewed, with the color of the light and with the color
_, character of the surfaoe.
The criterion by which the light intensity is judged must be strictly
JMiportional to the light incident upon the test plate, and must be inde-
Inident of each of the other improper variables just n^entioned, if the
■nits of the observation are to show the intensity of the light incident upon
be surface.
Whether or not the light falling upon the photometric device varies only
irtth that incident upon the test plate, depends upon the design and looa-
Ion of that plate.
The requirements for a theoretically correct test plate ^ftre:
First, a plaih white surface which, when viewed from the pohit of photo-
■Ktrie observation, obeys Lambert's law of the' cosines with reference to
fetensity of illamination produced by Ught incident upon its smiace at any
befination and from any direction.
Second, a material .which will not introduce errors due to color differences.
Thiid. a plate which may be placed at any angle.
Fourth, a location such that neither the body of the observer nor instni-
iBeDt parts shall obstruct lig^t which wolUd otherwise fall upon the plate.
It is, of course, desirable to measure all of the light which would oe inci-
dent axwn an object at the point to be considered. In all interior lighting
■ystems there is more or less diffused light, all of which has some illuminat-
B)^ value. In order to measure all of the effective lighL there must be no
objective interference with light incident upon the idate at any angle.
TUs means that all instrument parts, as well as the observer, must be
beneath or behind the surface of the test plate. This is possible only when
tnnsmitted h^t, instead of reflected light, is measured.
The only oiMor which is practicable is white, of as great purity as mav
he obtainable, and as free as possible from selective absorption. With such
• test plate, lights of different colors are credited with approximately their
true intensities, when the test plate is viewed from the pnotometrio device
has invented a photometer, as follows:
The apparatus consists of a tube, A. about 30 cm. long, which can be
noved up and down and swung in a horiaontal plane on the upright, c.
The itandard light. S, a beniine lamp, is contained in a lantern fastened to
the ri^t end of the tube, A. Within the tube. A, a circular plate of opal
I^MB can be moved from or towards the light, S; its distance from E is
lead in centimeters on the scale, a, by means of an index fastened to the
Pu>ion, P. At right angles to tube. A, a second tube, B, is fastened. This
tobe can be rotated in a vertical plane, and its position in reference to the
BoriaoQtal is read on the graduated circle, C. A Lummer-Brodhun prism
eootained in tube B in its axis of rotation ' receives light from the opal glass
plate in tube A, and reflects this light towards the eye-piece, O, so that the
eater half of the field of vision is illuminated by this light; the inner half is
moiniiiated by the light entering the tube^ B, through g.
In maidng measurements, the tube B is pointed toward the source of
fij^t to be measured. The light has to pass through a square box, p, in
^niieh may be inserted one or more opal glass plates, Jn oraer to diminish
me mteonty of the Ught, and thus to make it comparable with the standard
vht. The apparatus permits the measurement of light in the shape of a
flioe, as weUas the measurement of diffused light.
Since the measurement of diffused hght interests us most at present, a
ehort description of the method will not be out of place.
A white screen, the surfaoe of which is absolutely without luster, fur-
phed as part of the apparatus, is placed in a convenient position, either
uDnaoQtal or vertical, or at any desired inclination, toward the source of
hvit.
The photometer having been located at a convenient distance from the
>^*en, the tube B is pointed to the center of the screen. The distance of
uM photometer from the screen can be varied within very wide limits, the
0017 reitrietions being that the field of vision receives no other light than
^ Trans. Illuminating Engineering Society, October. 1907.
ELECTBIC UOHTINQ.
that aiuiialiac from thaiaraui. ThenaiMnry pr«»uM,„ ... . — .
hitvlni been obHrvscl. the oiiel ^ua plmte in the tuba A ig Ii»*«il m..
hklvaa of the 6M, of visioo spp»r MUftUy lUumiBBted. nw diatuK
(kli ^Mtm plate from the itudard ucht at (fai moiiMOt <d eqaal Bl
Fta. e. Prof. L. Webar'i Portable PhobunBtw.
ID b KBd OD the aeala o
lub*.1
PBOTOMETEBS.
!. A itandanl «uulla or jU aqulTsleat w piaoBil aiacUy ona nnUr dufauit
boo (k* vUm Mram, >ad lh« Mb*. B. (< Qm pbotonMMr i* poiDWd tomtdi
ilh* HI Mil. B tlut tlw eaDtw ol the HiMtii. wUeh i* mulcsd by ■ etom,
bNHiB the MDMr <rf ifa* 6«ld of viooD. A*iiuli«l«d ioFis-O, tin pboto-
■Mar must be ■> cduiad that tlM tyt, kwkifia tfaitxish Ih* aya-pieoa. laii
■Dikioa bat ibB iiluta termo. Tba to£a ol a " '
■niB la obaai v«J auy b* irmriad vithiii frida
o of botli hAh^oa ol tha fiald ol vUod havinc baon ob>
of aiJiiirHnt tha opkl cUb plsta ia tuba jl , tba oi
dilriuad Ucbt without tha
1; but tor turthar detaila tha laadar la nltml to tba
Im^ittaD of tha ijPiwimtiH by Prc4<aKH Wabar, BUUnitaAiiHdka ZtO-
Tba vbol* ■pP">tna oan aaoly ba lakea uart. and paekad in a box
■boiit 31 X S X 13 in bea. lo aoma OM*a tha baniiDa lainp mi^t wall ba
whloh tha Wsber ii fitted tor, lAUa It la B
nts thui tha latter inilnunent, and ]ai
t la Uluitrated In Fif. It*
- Pboicmatcn bui ba oonatruetad. ao
Diean BphrTica] oandl^powar of lampa.
— , . '—f by Pnfaaaor Hatthem both tor an
id toraadaaaant Umpa. (Trmni. A. I. E. E.)
'08. £IeclricaI Ktvitrn, LU.
p. 181. Jan. 3fi, '08. Bltclrieal Stvit
m <Lnidoo>. I^. p. H3. Ju. 31 'OS.
(
/
540 ELECTRIC LIGHTINQ.
A simple form of this type of photometer is the Ulbrioht flphora
meter. This consists of a large sphere coated on the inside with do!
paint and furnished with a small window of diffusing giass. The
IS introduced into the interior and a screen is so plaoed that the direct
of the lamp cannot fall on the window, which is consequently iUumin
by reflected rays alone. The theory shows that the intensity of such
mination is proportional to the total luminous flux, or the mean sphi
candle-power of the source within, so that it is necessary only to i '
meter tne lig^t issuing from the window to have a measure of these
titles. The sphere must be calibrated by the "substitution metlKxl,'
using an incandescent lamp standardised for mean spherical oaadle-poi
JBatiMi* of m«niina«<ii. — lUuminants are rated aocordmg to tl
candle-power and their volts, amperes or watts. Differences oeeur
practice as to what is meant by the candle-power, that is. in what directive
the candle-power is to be measured. In the earliest days incandeooenj
lamps were rated by their maximum candle-power; now. however, the
common practice is to use the mean horitonial candU-^power. In oo
ing lamps having differently shaped filaments this is in general not _
basis, since two lamps might give the same total flux of ught and yet
of them niiidit have a much smaller mean horijontal candle-power
the other. These difference) are recognised by the differences in the b|
ieal reduction factors of the two. A small cufference in spherical redi
tion factor mav have a very large influence on the results obtained
life-test. The fair way is to use the total flux oi hgjtit or the ftuan
candle-power as the basis for comparing lamps or lUuminants of
tjrpes. The American Nemst lamp is usually rated by its maximum oandli
power, that is, the candle-power immediately below it. The intensicy ii
this direction is increased considerably by the light reflected from the heatetj^l
coils and other parts of the lamp. No standard method for candle-poweiN
rating of arc lamps has ever been adopted in America. In Oenaaajr the|
mean lower honispherical intensity is chosen for this puipooe.
IK'mttm p«r candle. — The condition of operation of an incandes^
cent lamp is usually specified by the watts per candle, meaning, ordinarily,
the watts per mean horizontal candle. The efficiency of a lamp is inveraeiy*
proportional to its watts per candle. The life history of a carbon filament'
lamp is characterised by a small initial increase in candle-power lasting for
about 50 hours in the cfise of a 3.1 watt per candle-lamp and then by a.
unform decrease in candle-power until the lamp fails. This is aeoom-'
panied by a resiilarly increasing blackening of the bulb. It has been
shown (Sharp, EletUncal World, Vol. 48, p. 18), that the age of a lamp
may be estimated by an examination of the decree of bulb blackening.
The light from frosted lamps decreases more rapidly than that from ux»-
f rosted: ones, an effect which has been shown (Millar. Bleetrical Worid, April
20, 1907) to be due to the increased absorption of that portion of the H^t
which suffers multiple reflections. Any lam^ may be operated at any watts
per candle simply by raising or lowering the impressed voltage, but the life
of a lamp decreases very rapidly with decreased watts per candle. In opeia-
tion it is necessary to strike a balance between increased efficiency and in-
creased cost of lamp renewals. The standards are 3.1, 3.5 and 4.0 watts
per candle. Closely r^ulated voltage is essential to successful 3.1 watti
per candle operation.
After a lamp has reached a certain point in its decline in candle>power
and efficiency, it is more economical to replace it with a new one than to
consume energy in a wasteful device. The period of the me at which this
condition is reached is called the "emaahino point,** of the lamp. The
smashing point may be computed, but it is found in practioe that it is most
satisfactory to assume uniformly that its point has been reached when the
candle-power has decreased 20 per cent from the initial value. This con-
stitutes by common consent the close of the "useful life" of a carbon fila- ,
ment lamp.
Splierlcal CandIe-pow«r and IMatrlbntton Cfvrres. — A.
lamp filament giving a certain total flux of light may be made to gare a
greater or a smaller proportion of this in the horizontal direotion. Therr
1
INCANDESCENT LAMPS.
641
I fore the mean horusontal candle-power is not a trtie basis for oomparinK the
performance of lamps of different types. The "spherical reduction fao-
^lor," or ratio of mean spherical to mean horizontal candle>power must be
[ takien into consideration. The following curves and table give values for
; this factor for different types of lamps and the axial distribution of candle-
t jpower about the same types. The curves show also the Rousseau diagrams
' for the lamps, that is, curves the area enclosed by which is proportienal
to the mean spherical candle-power. The data were obtained at the Eleo-
trieal Testing Laboratories.
Lamp
Type.
1
2
3
4
5
6
7
Description.
Double loop.
Oval.
Small spiral; single turn.
Large spiral; sin^e turn.
Medium spiral; smgle turn.
Short-legged spiral ; double turn.
Ellipticalspiral. double turn, axis of ellipse horisontal.
Fia. 12.
Table I.
Lamp Type. '
Watts.
End-on c.p
MesD horizontal c.p. . . .
Mean spherical c.p. . . .
Ratio: Mean spherical c.p.
Mean horizontal c.p.
^Wq. Mean spherical c.p.
End-on c.p.
Ratio: End-on c.p.
Mean horizontal c.p.
Watts per mean spherical .
^atts per mean horizontal
Jl«tte per end-on ....
1
49.6
5.06
16.00
12.82
0.802
2.54
0.316
13.88
3.10
9.8
2
49.6
7.3
16.0
13.19
0.825
1.81
0.456
3.76
3.10
6.78
3
63.5
7.7
16.0
13.42
0.840
1.74
0.481
4.73
3.97
8.26
4
56.6
9.6
16.0
13.63
0.854
1.42
0.602
4.15
3.52
5.90
5
53.8
9.31
16.0
13.78
0.862
1.48
0.582
3.91
3.36
5.78
6
59.3
11.4
16.0
14.07
0.880
1.23
0.712
4.22
3.70
5.20
64.74
15.9
16.0
15:72
0.^83
0.864
0.092
4.d9
4.02
4.04
§
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IKCANDESCENT LAMPS.
64S
e
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• 3k • ■ • • •
• ^^ • • • • •
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r
644 ELECTRIC LIGHTING.
Tktt Proper lJii« of IncMideacoiit
(From a Circular of the General Electric Company.)
A lamp to gire satisfaction must not only be properly made, bat ft h
also be properly used. A lamp of tlie highest quality may be so misoMdj
to give only a small fraction of its rated light capacity. Proper iiao, pnrf|
cing a maximum of light at a minimum expense, requires :
That the lamps be burned at marked roltage.
That the voltage be kept constant.
That lamps be replaced whenerer they get dim.
The last requirement Is not considered economical by many usees
prize lamps that have long life, and insist on using them as long as
will burn. Let us see by an example if extremely long life is deeirabie.
As the cost of current varies greatly, we will assume an avarmge cost
one-half cent per lamp hour. If a rated 16-candle-power lamp, bi
for 1000 hours, be burnetl an additional 1000 hours, it takes practical Iv the
current during the last period, but gives an average light of only ab
candles. The cost of current for the 2U00 hours is fio.uo. A now lamp eo^
ao to 25 cents; and had three lamps, with a life of about 700 hours each, bMJ
used during the entire period, the average light would have been f afl
doubled, at an added expense of not more than GO cents, or 5 % of oost^
current. In other words, by adding 5 % to operating expense fr«>res^' "
the cost of the two renewal lamps) tiie customer would add 100 % to
light given. One new lamp gives a lieht equal to two old ones at half
cost of current. If the old lamps gave Tight enough, the new lamps ««
halve the number of lamps in use, and produce the same light with half tfl
current. j
It is important to note that the above example is based on results obtaiM
with the Highest grade of lamps. With an Inferior quality of lamp the if
gument against extremely long life would be still stronger and the asMi
slty of frequent renewals of lamps much greater. _^
Thus, from any point of view, it Is false economy to select lamps wttkl
sole regard for long life. Lamps should be renewed when dim, foriaM
other wav can light be produced economically.
The points to be remembered are as follows : ^
Do not run pressure above the voltage of the lamps. Increased presi^
means extra power; and although the old lamps may thus give more Upl
for a while, every new lamp that does not break from the excessive presstfl
will deteriorate very rapidly and give greatly diminished light. ^
Do not treat incandescent lamps like lamp chimneys, and use themiiatl
they break. They should be renewed whenever they get dim.
lilfo mmA Gaiidlo-poiror of Idunps*
Since the prime function of an incandescent lamp is to give light, the M
lamp is that which f^ves maximum light at minimum cost. This u ■•
exceedingly simple axiom, and yet few users of lamps follow it out in pne*
tioe. Lamps are repeat«aly selected for loni^ life, irrespective of nood, an*
form candle-power. Lamps are often continued in use long after thflT
candle-power has seriously diminished.
An examination of the characteristifes of an incandescent lamp will gi^
a clear understanding of the principles applying to their selection and ma
A theoretically perfect lamp would maintain its normal candle-poiitf
indefinitely, or until the lamp was broken. In practice the deterioration of
the lamp filament causes a steady loss of candle-power.
Hgyiirdtaig' Mjotm in Csmdle-power. — The drop in candle-pojstf.
is a cnaracteristie of an incandescent lamp always to be borne in miad>'
The relative drop or loss of candle-power, other thiiun being eqadi
determines the comparative value of different lamps. We may haw »
lamp that loses 50 per cent in candle-power inside of 200 hours on a ^
watt basis. Considered from the standpoint of life only, audi lamps ait
mCANDEBCENT LAMPS. 545
leotw beeaiwe their filaments deterioimte to lueh » denee that it to
Ically impoadbla to supply enough current to brishten them up to the
kldnc point, but no disoeming station manafer would want such dim
ips, eyen with unlimited life. As in the selection of incandescent lamps
in their use — the exclusive consideration of life leads to poor results.
of candle>power in a lamp sooner or later makes it uneconomical to
itinue in use.
A customer cares little how efficiently a station is operated, but is much
■Memed about the quality of light fuitushed. Some means of keeping the
'average life bdow 600 hours should be adopted by every lii^ting company
that hss any repird for the economical production of light, or the satisf ac-
tioo of their oustomers.
A simple method is to fix the average life at 600 hours or less, and then
\ detemiine from the station record how many lamps should be renewed each
.month to keep the average Ufe within this limit. The required number of
kouis should DO renewed eadi month.
[. If, for example, a station decides on an average life not to exceed 600
'iMwa and the station records sImw that on the average 60.000 lamp hours of
camnt are sopiriied i
100 lamps a month.
camnt are sopiriled monthly, then it would be neoessaiy to renew J^^ or
mtm MMmmmwimmmm of
S«lectl«m mmA Vee of Vnuuf anM«vs» — Poor regulation
' of ToltaiBB probably results in more trouble with oustomers than any othv
' fsolt in deetrio li^ittng sovioe.
Some eentral station managera act on the theory that so long as the life
of th» lamp is satisfactory, an Increase of voltaae, either temporary or per-
manent, will Increase the averase lifljht. The fact is that when lamps are
iMuned above their normal rating the average candle-power of au the
lamps on the circuit is decreased; and if the station is on a meter basis, it
Increases the amount of the customers' bills.
■vtia mt Kxc«aaive VoltBsrg. — Excessive voltace is thus a double
VTor — it deereases the total light of the lamps, and mcreases the jpower
eonsumed. The loss of light displeases the customers and discredits the
aenrice. If light is sold by meter, the increased power consumption dissat-
isfles the customers; if light is sold by contract, the additional power is a
dead loss to the station. If increased light is needed, 20 candle-power
lamps should be installed, instead of raising the pressure. Their first cost
is the lame as 16 candle-power lamps; they take but little more current
tlum 16 candle-power lamps operated at high voltage, and glTC greater
STerage light.
Increased pressure also decreases the oommerclal life of the lamp; and
this decrease is at a far more rapid rate than the increase of pressure, as
•hown in the following table. This table shows the decrease in life of
standard 3.1 watt lamps, due to increase of normal voltage.
Per Cent of Normal Yoltage. Life Factor.
100 1.000
101 0.796
102 .615
103 4B
10ft 40
105 84
106 20
Phm this table it Is seen that 3% increase of voltage halves the life of a
lamp, while 6% Increase reduces the life by two-thirds.
Irregular pressure, therefore, necessarily results in the use of lamps in
which the power consumption per candle is greater than a well-regulated
pressure would allow. The result is reduced capacity of station, and
reduced station eflleleney.
646 ELECTRIC UOHTINQ.
Th6B0' remarkB apply with spedal foro« to alternating-oiiiTaiit
alnoe we haTe here two sources of possible irregularity in Toltace —
flenerator and the transformer. Poor regulation is most apt to oooor in i
transformers, and the ntmoet oare should, therefore, be taken in th^r
tion and use. The elBoiency of the average lamp on alternating ayn
is nearly 4 watts per oandle. With good regulation obtained by the ml
gent use of modern transformers, the use of lamps of an efBciency of
watts per candle becomes practicable. It is thus possible to eaTe 25 % I
power consumption at the lamps, and inoceaae the capacity of the
and transfonners by the same amount.
The general adoption of higher voltage secondaries mves smaller loee ia
wires, and permits the use of larger transformer units, tnus grsatly improv-
ing the regulation. On this account 60-volt lamps are gradually goinc
out of use. The replacement of a number of small transfonners bjr one
large unit, and of old, inefficient transformere by modem types, haa alaa.
been of immense advantage to stations. A large number of statioa^
however, still retain these old transformers, and load their dreuits witk
large numbers of small units. Such stations necessarilv suffer from loss
of power, bad regulation, and a generally deteriorated lifting serviee.
Simply as a return on the investment, it would pay all such stations to aemp
their old transformers and replace them with large and modem units.
Proper care in the selection of transformers considers the quality and tba
sise. Quality is the essential consideration, and should have preferenoe over
first cost- No make of transformer should be permitted on a station's eir*
ouit that does not maintain its voltage well within 3 per cent from full load
to no load. The simple rule regarding sise is to use as large units as posaiUe,
and thus reduce the number of units as far as the distribution oi service
permits. Every alternating station should aim to so improve regulation as
to permit the satisfactory use of 3.1-watt lampe.
Good regulation is eminently important to preserve the average life and
light of the lamps, to prevent the increase of power consumed by the lamps,
and to permit the use of lamps of lower power consumption, so that bm
the etBciency and capacity of the station may be increased.
Constant voltage at the lamps can be maintained only by constant use of
reliable portable instruments. Ko switchboard instrument should be
relied on. without frequent checking by some reliable standard. Owing to
the varying drop at different loads, constant voltage at the station Is not
what is wanted. Pressure readings should be taken at customers' lamps at
numerous points, the readings being made at times of maximum, average
and minimum load. Not less than five to ten readings should be made at
each point visited, the volt-meter beinf left in circuit for four or five misf
utes, and readings being taken every flneen seconds. The average of all the
readings gives the average voltage of the circuits. Lamps should be (or-
dered for this voltage, or if desired, the voltase of the circuits can be re-
duced or increased to suit the lamps in use. The practical points are to
determine the average voltage at frequent periods with a portable volt-
meter at various points of the circuits, and then to arrange the voltage of
the lamps and circuits so that they agree.
GaMdle-Hoors— Hie Regvlatleit of Iiweip VAl«e.
The amount of light given by lamps of the same efRcIency is the only
proper measure of their value. The amount of light given, expressed 1b
candle-hours, is the product of the average candle-power for a given period
by the length of the period in hours.
Many of the best central station managers consider that a lamp has passed
Its useful life when it has lost 20 % of its initial candle-power. An the ease
of a 16 candle-power lamp, the limit would be 12.8 candle-power. Ths
period of time a lamp barns until it loses 20 % of its candle-power may
therefore be accepted as its useful life. The product of this period in honn
by the average oandle-power gives the *' candle-hours " of U^t for asy
given lamp.
The better a lamp maintaina its candle-power under equal conditions of
comparison the greater will be the period of "useful lifCi" and therefore
^e greater will oe the "candle-hours." This measure is, therefore, the
only proper one with which to compare lamps and determine their quality*
INCANDESCENT LAMPS.
S47
.lb» imfiliQ^ method of oompariaon is as foDoms Lamps of
power and voltage are burned at the same initial emoienoy ol 8.1
oaodle cm circuits whose voltage is maintained exaotly normal.
ol 50, 75^ or 100 hours the lamps are removed from the oireuite
candle-power reading! taken, the lampe being replaced in dreuit at the
cf each reading. Readings are thus continued until the candle-power
a to 80 % of normal. The results obtained are then plotted in curves,
the areas under these eurves give the " candle-hours uid the relative
of the difFerent lamps.
In the following table is shown the variation in candle-power and effl«
ciencjr of standard 3.1 wattHamps due to variation of normal voltage.
Per Cent of Normal
Voltage.
Per Cent of Normal
Oandle-power.
Watts per Candle.
90
63
4.68
01
67
4.46
92
61
4.26
93
66
4.1
94
691
8.92
96
74
8.76
90
79
8.6
97
84
3.45
98
89
3.34
99
94i
3.22
100
100
8.1
101
106
2.99
102
112
2.9
103
118
i:l
104
1244
105
131
2.62
106
138}
2.54
Eiample: Lampe of 16 candle-power, 106 volts, and 3.1 watts, if burned
ftt98f of normal voltage, or 103 volts, will give 88 % of 16 candle-power, or
14) eandle-power, and the efBcienc j will be 4.94 watts per candle.
X«aaap ReBewala.
The importance and necessity of proper lamp renewals applies foroiblv
to sO stations, regardless of the cost of power, and whether lamp renewals
u« diamd for or furnished free. The policy of free-lamp renewals at the
present low price of lamps is, however, preferable for both station and cus-
tomer. Free lam]) renewals ^ve a station that full and complete control of
their Gifting service so requisite to perfect results.
Palate tm b« ]Keaa«Mb«»v«d«
That a constant pressure at the lampe must be maintained.
That the lamps are not to be used to the point ci breakage — they should
be renewed when they beocnne dim.
That satisfaction to customers, and the success of electric lighting, are
<^*P«Mient upon good, full, and clear light, which old, black, and dim lampe
eeaootgive.
(
548
ELECTRIC LIGHTING.
That to furnish a cood, full, and dear tight is as mudi a part of the
inc company's business as to Supply currant to licht the Uunps.
That a oompany should always endeavor to keep the averace life of
within 600 hours.
That to renew dim lamiM properly on the free renewal system,
should examine the drcuits regularly ynhen the lamps are buRuhs-
lamp renewals are eharged to customers, induce them to exchange
dim lamps.
t lABipa.
linoaltj of Ii
As showing the quality of incandesoent li^t, we present here s eunra
showing the relative luminosity of au Incandescent lamp at different regioM
of the visible spectrum.
On this subject Prof. E. L. Nichols states the following :
** The most important wave-lengths, so far as light-giving power Is eon*
cemed, are those which form the yellow of the speiotrum, and the relatif*
too
LUMINOSITY OF
INCANDESCENT LAMP
400 SELATIVC
WAVE UENOTM
RED ORANOr YELLOW
OftEER
SLUE VIOLET. .
Fig. 13. Regions of Spectrum.
luminosity falls off rapidly both toward the red and the violet. The lonMr
waves have, however, ranch more influence upon the candle-power than the
more refrangible ravs.
" Luminosity Is the factor which we must take into account in seeking t
complete expression for the efficiency of any source of illumlnatton, «hI
the method to be pursued in the determination of luminosity must ds^toA
upon the use to which the light is applied. If we estimato light bV iti
power of bringing out the colors of natural objects, the value which v«
place upon the blue and violet rays must be very different from that whidi
would be ascribed to them if we consider merely their power of illniBiiis-
tion as applied to black and white. In a picture gallery, for instance, or
upon the stage, the value of an llluminant increases with the temperstois
of the incandescent material out of all proportion to the candle-poirar,
whereas candle-power affords an excellent measure of the light to iM
used in a reading room.
INCANDESCENT LAMPS.
549
ip^ — The to-oalled "metal-
, M applied to earbon filamentfl eonaiati in licatana the 61amentc
loan enoimoiMly hish temperature both before and alter ffaahing. ueinM
A carbon tube eleetric furnace for the puipoee. The term **metalttBed"
V applied on aeeount of the positive temperature coefficient which the
' ftimentB acquire in the proceeB. The useful life of the metallised filament
limpe at 2JS w.p^o. is said to be the same as that of the ordinary carbon lamp
•t 3.1 w. p.
e.
The style of label employed for Oem Lamps is as here shown. These
labels are printed for all the Toltages from 100 to 130 and
for the Tanous sizes of lamps.
Am shown In the cut of label, only the total wattage of
lamp and the rolta are printed. Candle-power yalaes
are not ciTen. as these Talnes yary with the different
forms or reflectors. (See candle-power distribution
eorres.) The Toltage markings are arranged to show
three roltages in steps two rolts apart, and this proyides
a ready method of yarying the efllcleney and life of lamps
to tnit different conditions. The yalues at each of the
three yoltages are shown in the following table :
Lamps ahoald, of course, be ordered at the *' Top " or
int voltage (Vl) wheneyer possible, so as to secure the full
lighting yalue said maTimnm efliciency and brlllian<7. Fio. 14.
Talble •€ Valnce at let, Smt
Voltage of Circuit.
Per
cent
Total
Watts.
Per cent
of 0. p.
Values.
Eff.in
w. p. c.
(mean
horisontal
c.p.)
Useful
Life
in
hours.
Same as ** Top " or 1st Voltage (VI)
Same as '*Middle " or 2nd Voltage (V3)
flsneas" Bottom" or 8rd Voltage (V8)
100%
100%
2.6
2.66
8.8
600
700
1^)00
The filament of this lamp is a fine wire of metallic tantalum. The high
flndting point and low vapor pressure of this metal make it possible to
cpeiate the lamps at 2.0 w. p^c. with a life comparable with that of the
ordinary lamp at 3.1 w. p. c. The life on alternating current is much shorter,
tlna on direct current and is a function of the frequency. Fig. 15 shows
freehand drawingi of microscopic views of the tantalum filament as affected
by rise on alternating and direct current. The vertical distribution of
mtspaity changes dunng the life of the lamp, the horisontal intensity
gminiwhing more rapidly than the spherical, due chiefly to more rapid
bulb blackening in the horisontal sone. On this account the spherical
nductaon factor also changss. (See Fig. 10.) CSiaracteristic life curves
of tantalum lamps manufactured in Grermany in about 1904, are shown
m FIgi 17 and 18. These tests were made in the Electrical Testing Lab-
ontories. ^ee Sharp, ^sio Typm of Ineandeteml Lamp§, Proc. A. I. E. £.,
lW,p.8».)
SLEcraic LiuatiHQ,
Fio. 15. Itiaroaoopio Views of tlia TaaUlum FIluQCDt
INCANDiiSCfiNT IiAMPB.
551
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ai
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UFB CURVES OP REP.BE8ENTAX1VI
TANTALUM LAMPt
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SLECTBIC UQBTISQ.
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id^!--'4*f^
Fig. 18. Curves d Tantalum and Carfoon Lamps.
/
INCANDESCENT I^HPS.
,_ _— . ^ ^rftbla ooDdition of aiMcmdoD ■- ->
s. nrhlsfa ii ItM poiDt
Fn. 10. Tata of Six
Mil 1 1 mf rfcatu la T«lf|ii
Chut*<rltb 9 per c«ot laenus ja toIuc* nbovs noima).
CkDiUf-pQver. Watt* ptrOuidla.
CMboo +M% -15%
MMolliHd +37% -13%
TiBtalum +^S "I'S
r
ELECTRIC UGHTINa.
J
M 1 M M
~
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HAHACTERISTIO CURVES
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Fra. 20. OuusaMriatiB Curves of Tan(sleii. l^lalum, If eulGied
■ffeeled by Toltegs fluotiutEii
lampi. The opermltng temperBtnra of the Tcjit'
gten It >o blrh IhaE tEe liglit !■ of pecoliu ud
(greeable wHUene«. maoh better fltt*il for thf
luatcbliig of colon tbsa !■ tbat of tbs cu-bcs
burning Iimpa for atreet lighting an tim
bis. Tbs life of ■ Tonnten multiple lams
S watts per candlelB aald to be N
Bnllatln of the Engineering Departmenl ol the
Batlonal Electric Lump AsMKlatloa.
OprraMBgr C<Mt.~Table 6 ahoiri tbe total
of power. The ooaiUoed ooataf power and lamp
MTljig effeeted by ibt .
when the coat of power la high.
At costs of power gre»ter tl
if high efflcisDCj lamia.
t cocl of the lunp awl
ipting only the higher
cheaper than the Tunnten ai coata of ponr
i>na»«yc]e h] ternatlag and four ceodiwikllanU
Bout on direct current.
INCANDESCENT LAMPS.
655
AHD HOW IlVCAimSSCBSV
Bt MORTimB NORDBN.
Tba foOowinc data hftra been oollated to show the yearly eonsumption of
corrcnt ner 10 o.p. lamp on the oircuita of a large central station company,
■mnc the yearly average of current used in kw.^iours. The data represent
ten plants all operated by the one company :
V«teU •€
C«M«uMF««mf SM^wlar Yearly C«m.
1 Greenhouse
M Colleges and schools
127 Chnrehes
8 Parks
150 Residences
64 l>entists* and physicians' oAees ....
Ml Fsotories
8 Signs
14 Public halls
6 Dressmakers
1 Gndn elerator
m Mnnidpal buildings, hospitals, armories and
city halls
HM Clnhs and lodge rooms
W Nine o'clock stores
401 BeTen o'clock stores
M» Eight o'clock stores
187 Livery stables and stables
96 Eleven o'clock stores
987 OflSee buildings and ofllces
10 Theaters
0 Boad houses
IB Banks and insurance companies ....
11 Ten o'clock stores
2 Cold storage companies
4 B. B. terminals and docks
180 Drag, confectionery and cigar stores . .
610 Saloons, restanrants and concert halls .
327 Six o'clock stores
92 Wholesale batchers
16 Commission dealers
8 Tvelre o'clock stores
8 Steamship docks
6 Hotels
28 Bailroad stations
2 All night stores
4804 enstommni.
liightS.
Kir.-hoars.
M
1.33
2,888
6.70
11,616
7.76
416
9.24
40/106
10.78
1,008
16.10
21,986
16JS8
865
18.48
1,781
18.81
111
90.24
94
20.76
14,604
24.79
7,891
24.82
4,433
26J6
17,823
26US6
18,228
27.10
1,776
29.66
024
80^
7,363
80.65
10,661
32.13
306
82.70
3,322
83.80
839
88.34
168
40.82
864
42.14
4.37t>
42.44
17,602
43.62
23,684
46.61
1,012
46.92
618
48.06
170
62.44
2,203
61.71
1,009
66.
900
118.98
410
218.06
214,934
Grand average
27.28
II
ill
%
IP
Jll
'ill
lU
■11
111
pi
II
INCANDESCENT LAMPS.
667
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558 ELECTRIC lilGHTINQ.
Cnh»nMStoii«tlo»« — ^This lamp is an arc lamp rather than an incaiidi
lamp, the arc having a meroui^ cathode and pmunng throufl^ vapor of me.
at low vapor tension. Hie hght probably results from the eieeirc»-lanii!
oenoe ol the meroury vapor and not from any very hi^ temperature
duced either at the anode, the cathode or in the arc stream. Beins prod<
in this way, the lii^t shows not a continuous spectrum of all the or
but a discontinuous or line spectrum ohaxaoteristic <A mercury. The
oentage of the electrical energy which is converted into light is relatj
hi|^, and the lamp is very efficient. It would constitute for many puxi
an almost ideal source of li^t were it not for the unfortunate zaet tfail
in the spectrum of mercuzy red is almost entirdy lacking. The result is thai
the li^t d this lamp has a tint which to most peopw is very diatawtrfuj,
name& a strongly greenish hue. Red obj^ts look black or purple in %
and Ml colors containing red are falsely rendered. When this oharade^
istic is not objectionable the Cooper-Hewitt lamp may be used to good
advantain. It is asserted that the liidit is very favorable for the esr-en.
causing uttle fatigue. It has been used in draupiting rooms to sonoe ex-
tent. Its actinic powera are hi||h, due to the presence of bri^t violet }aam
in its spectrum, hence it Is a desirable source oi li^t for night photocFaphy*
for copying, blue-printing, etc.
Pli^twHietvy. — The photometry of the Cooper-Hewitt lamp is attended
with considerable difficiUties due to the large linear dimensions of the lamp,
and to the wide divergence of the color of its ll^ht from that of other soureei-
As a result of its large linear dimensions it is necessary to place the laacm
at a considerable distance from the photometer. For distances iriiioh
are small in comparison with the length of the lamp, the intensity of tbs
li^t does not diminish as the square of the distance. The difBculties due
to the color of the light are two-fold. In the first place photometer aettinfi
are difficult and uncertain to make unless a flicker photometer is used, and
the personal equation of the operator is a large one. In the second place
what is known as the Purhinje Phenomenon plays an important part in the
results. This is a physiological effect, accordini^ to which if a reddirii and
a peenish or a bluish light appear equally bnj^t when the inteoai^ of
each is hiffh, the reddish li^t appears much fainter than the other fraea
the intensity is greatly diminished. It follows from this that the apparent
candle-power of the Cooper-Hewitt lamp ^en photometered against aa
ordinary standard, such as an incandescent lamp, is higher the farther the
lamps are removed from the photometer or the dimmer the tUuminatiae
on the photometer disk. In order to get even approximate^ aooorats
results in the photometry of this lamp a standard illuminauon on tha
1>hotometer disk must be chosen and adhered to. No sudi standard iUiuar
nation has as yet been designated and established.
The following matter is condensed from an article in the Bleeineai Age.
The Cooper-Hewitt lamp consists essentially of a glasa tube, from which
all the air has been exhausted, but which contains a small amount of liqnid
mercury and is filled with mercury vapor. At the ends of the tube ai«
means for introducing the electric current. At the positive end the tabs
swells out| forming a chamber, which is called the condensing chamber
A platinum wire is sealed into each end of the lamp. At the positive end
the wire connects either with a small puddle of mercury or a piece of iroa.
according to the type of electrode used, and this constitutes the positivs
electrode, or anode. At the negative end the wire connects with a small
puddle or mercury constituting the n^ative dectrode, or cathode.
The lamp may be made of such dimensions as to make it suitable for a
direct-current line of any assigned voltage. Most lamps are designed to
run at a pressure of about 115 volts. A lamp about 4 feet in length and
1 inch in diameter would be suitable for this voltage and would work bert
on a current of about 3 amperes.
Before being started, the electrical resistance of a mercury vapor lamp
b very hi^.
This nevitive electrode resistance to starting ma^^ be almost totally
destroyed in various ways. One method consists simply in tilting the
lamp until the two electrodes are brought into connection by a thin stream
of liquid meroury along the length of the tube; then, upon tilting back.
INCANDESCENT LAMPS. &59
Cmits is started whiefa prevaito the high cathode reeistuioe from making
appearanoe, and the lamp continues to operate until the current 10 turned
\9/B.' Another method of starting is to send a small, momentary high-
jfenmoa current from an inductance coil throui^ the lampj which at toe
iffBine tin&e 10 connected with the low-voltage mains. This high-tension
[Mtfrent penetrates the high cathode resistance, and the current from the
! iDiw^voltage xnains follows, and if this latter current be great enough the
■ hia^ cathode resistance does not again make its appearance until the oun>
1 18 turned off; and if it is desired to relight the lamp the same procedure
to be repeated. To facilitate the starting of the lamp by this method
so-ealie«l "starting band" is employed. This is simpl:^ a narrow, thin,
metallie band attached to the outoiae surface of the lamp in the neighbor-
hood of the cathode, and connected by a wire to the positive temunal of
the lamp.
In the latest model ot automatic lamps this operation is accomplished
by the use of a "shifter." This consists of an evacuated glass bulb oon-
taining mercury which is shifted by the action of an electromagnet when
the circuit ia dosed and whidi interrupts the current. Thereby a high
potential Is induced which starts the lamp.
A view of this lamp is shown in Fig. 22, of the interior of the auxiliary box
ia Fis* 23, and a diagram of connections m Fig. 26.
^•'^ Fio. 22. Type " P " Lamp.
The renstance which a mercury arc offers to the passage of electric
eurrent may be separated into three distinct parts: — First, the resist-
ance encountered l^ the current in passing from the anode into the
▼apor ; eeoond, the resistance of the vapor column itself; and third, the re-
sMtanee encountered by the current m passing from the vapor into the
cathode.
In the commercial lamp the potential drop over the anode is about eight
Tolta and is approximately indepoident of^the magnitude of the current
flowing and the diameter of the tube. The anode resistance, then, variee
i&wady with the eurrent. The potential drop over the cathode is about
five Toita and is approximately independent of the diameter of the tube
and of the magnitude of the current flowing, provided that the. current is
aboTe a certain minimum value, depending upon the inductance and re-
sistance in series with the lamp. If the current falls below this minimum
value,^ the cathode resistance immediately becomes enormous and the
lamp ia extiiu^ished. A certain amount of inductance and resistance is
usually plaoea in series with the lamp, as this has a beneficial effect, caus-
ing the lamp to operate more steadily.
In fixing the resistance of the vapor to the passage of the currmt, four
quantities predominate, namely, the length of the tube, the diameter of the
tube, the magnitude of the current, and the density of the vapor.
The results can be roughly expressed as follows: — The resistance of
a lamp increases directly with its length; it decreasee with increase of its
diameter and at a (plater rate when the current and diameter are small
and the vapor density large; it decreases with increase of the current and
at a greater rate when the current and diameter are small and the vapor
density large; it increases with inorease of the vapor density and almost
560 ELECTRIC ug:
dirastly, ■Ithmifh at ■ otrMin vktu* o( thi
mntwita and different diAmoten), the rat
•briipUy aad i* Itt* lor value* of the deoa
it Ufor lewt TBluee.
WImb the vapor detuity ii qnila hi«h, ■
jer fi^i the tube; and whin
Coil. 6. Ballut. 7. Shifter.
pmura of ■ lamp optratinfl under nortnal oonditbni U In the tMJshlun'
bood of one DiJiimeCer of niarcury.
It baa bna obHrved by Dr. Hewitt that then la a value of the vapar
danaitjr at which the light effioieocy of a lamp ii creatert, and tanipg r>
dcngned to run at this dennty whm Ihny an to Be oparaMd undsr miii-
martial coBditiona. Id order to maintain the denaity at the piDpo- point
the oondeneing ehamber mentioned at Ibe beginning of thia anjel* u ra-
ployed. Thi* cbambar oaually, though -■ "-
of Ka dnH
. aitd oonaequvt^
.'hith i» quite chiM
other parte of the lanV'
a the great«*t light idfi-
. imembered that thenm^
tinually vaporiiing, owing to the heat producn
^
INCANDESCENT LAUFB.
561
the eomnt. Aft«r oondenaiiig in the oondeDoios chamber the mercury
bade into the cathode end, and after a while aeain takee its turn at
▼aporiied.
e efficaeDcy is said to be somewhat higher than that of the are lamp,
and mueh higlMr than that of the incandescent light.
Fio. 26. Diagram Illustrating the Method of Op-
erating Lamps in "— '—
MMM
1
S
]-^ww-
QUIM-IMAK SWITON
IWNIQTilMOC OOlk
rrARTiM
■AND
^
Flo. 27. Diagram illustrating the method of starting by high-tension dis-
ebsnES. To li(^t the lamp, the main switch, which is mounted on a small
psiM board, is closed, and then the lever handle on the quick-break
nricdi is pressed down, thus completing a circuit through the series
nristances and inductances, charging the coil. On releasing the
hsodle the quick-break switch autotnaticallv opens the circuit and
the disdiarge df the coil pawnfn througdi the lamp, breaking down
ill reaistaace and establishing a path for the main current.
ELEdTRIC LIQHTINO.
Euly in 1893 Dr. Waltber NemM exhjbitsd
type of inundescent electrie luop. Mr. W«
patflotfl And pluwd ftt pmrk upon it a atbff of t/n^ii
a tato th« preaeat commerciu form in Uiifl CDuntr^ .
The tishl-emittinceJament of the btmp w developed by the Nenut I^mp
Company of Pittsbutih. is termed a slower." It ig made by p
through ■ die. a doujih compoeed of the oiidea of the imre eauiha
3*
ue iMiiiliaaiii lb<
rho have dBrdopiil
■ an oxide inopkble o
operative in the opeDur. The presence of oxygen la easantial. Olovaaaie
innulatorB when ooLri, but become oonduetort whOE hot, henev Ihey mnet ta
heated before they will oonduct declricity raffidanlly w^ to maintiiD
"he charapl eristic of the slower with refcrBnoe to voLtage UeaibtlowB: —
the current traveraing the glower u mcreued. the voltage acn» iU Ifl^
hea drops off with increasing rapidity u the euireat through the gtowB
ated oE the Mcending^part of the curve at a point just prewUng tlat ol
of the glower mak« the current difficult of control without k MMdjiM
reeiBtance in seriei with it. Thin balFsAing ifl accompliBbsd by meanvef
a fine Iron wire mounted in a BmaJi ;laas tube filled with hydrogeo. 1^
~ ~ . ' '. failed critical temperature, the prop«rt]' of
b great rapidity with riiinf tvn^ntun.
THE NERNST LAMP. 563
' TliB iiiaalii II nautaDM Mmparmtura ooeSciant of ft Aymc nur thus
Ik* raor* ih»n eounter-bAluiwl by the tcmperaturfl ooefficiflot of too iron
*in ballBst pUoed in Hriet with it. For k 10% >iH in cLtrreut tha rniM-
Hce'uilheballul increuH 1S0%, » that & glower Ibiu Dratectsd at anna
>MPHiw optntive throuch • wide nuue of T^ti^e.
(Idas in itmnina'
The beaun coruiM of thin
de nuufl of Taltl^e.
icreioJ lamp reqiurei
r» by a refraeiory tf
coEutrueted with a
itaut faora tbs dreuit aa ■oon a> the slowen li(bt.
A CToefal idw at tba uoiuttiMtioa ^ Uie lamp and (< <U priaoipal part*
icceiiia' witli bd uodentandiiic of its eleotrioal eooneetlona may M fained
SGLCumU/iflP
p.;r
sUoD of a llanut lamp when the iwitch ia ti
ba cntmtt tiainiw through the heater, brinf
jr<nlmity of the glower Co the beater reeull
Qduotor. tbrou^h which the curreiit then pi
(*) the ■rmature of tbe cut-out
it ii atlneted: and (S) Ihii c
•wm in opeiatiDii luiliJ the o<
"'tfio hi
the ewHch which oooUola tbe lamp circuit allows the ci
Iill_b]to place asain. thug eoODeetiDK the beaten^ tea<ly :
if the Nemn lamp
564
RLECTRIC LIGHTING.
curi'gut in the nnilti;de glower lamp than \b the ease wh6n they are
in the open air, this dmerence amounting to about 16 Tolta in
glower lamp.
Pkoteaeetrlc Teats of Varlooa Ill«ail«a»<a ^y BTatt
Sl«ctrtc Ur^t Aaa«clatioA.
lUuminants.
Multiple
D.C. Arc.
Multiple
A.C Arc.
Nemst 6-Gloi
W^Fm
OpaL
Opal.
Clear
Giobee and Shades.
Inner.
Clear
Inner.
Clear
Clear
Globe.
Opal.
Globe.
OpaL
Outer.
Outer.
Shade.
E.M.F.
110
110
226
226.5
226
Current
4.9
6.29
2.4
2.4
2.4
Watts
629
417
642
648
542
Power Factor
1
.6
1
1
1
Mean Spherical c.p. . .
Mean Hemispherical c.p.
182
140
168.9
168.6
155.8
239
167
289
258.6
254.2
Watts per Spherical c.p.
Watts per Hemispher. o.p.
2.90
8.02
8.30
3.22
3.48
2.26
2.63
1.88
2.10
2.05
Illununants.
Globes and Shades.
E.M.F
Current
Watts
Power Factor .....
Mean Spherical cp. . .
Mean Hemisphencal o.p.
Watts per Spherical cp.
Watts per Hemispher. cp.
Nemst 3-Glower.
Nemst 1
Clear
Globe.
Sand
Blasted
Globe.
Clear
H.C.
Opal.
Shade.
Clear
Globe.
218.8
219.5
220
223.7
1.2
1.2
1.2
0.4
262
263
264
89
1
1
1
1
65.1
61.5
68.6
21.8
112.6
96.9
118.3
38.7
4.04
4.28
3.86
4.11
2.33
2.72
2.23
2.31
Sand
Blasted
Globe
220.5
0.4
88
I
20.5
31.8
4.S
2.78
The British unit of o.p. used in above.
The arc lamp figures were taken from the R^iort of the Oommittae for
Investigating the Photometric Values of Arc Lamps, read before tlis
National Electric Light Association in May. 1900. The Nemst lamp dste
were obtained from the report of the same committee which was presatsn
at the Twenty-Sixth Convention in May, 1903.
llIat«tenAnoe. — The frame and connections of the Nemst Itaap ktn
a permanent structure having an indefinite life, but its perishable parti
have from time to time to be roiewed. Of these, the ballast has a fife
averaging 25,000 hours. The heater has a life averaging about 8 months
in ordinary use. The glower, however, like the incandescent lamp filaiwtt
has a practically definite term of use at the end of whi<^ it would bt
advisable to replace it whether burnt out or not. 800 hours are gLyntk by tin
company as the guaranteed life on 60 cycles.
JB«lwTior o« Altenuatlnr mmA IMrect CmrrmmL --Unlili
the carbon incandescent ]am|> the life of glowers is not the same «>
direct current as on alternating current, and is affected evten hf tibt
frequency of the latter. The American grower was ooostrueted origmafly
for use on alternating current only, while in Europe direct cuirant luni
predominated. The direct current lamp in this country is a oomparativHy
recent devriopment and its grower life is shorter than that of the ^ow
used with alternating current.
THE UOORE VACUUM TUBE UOHT.
:■ !■•«■■ VAOVTH TUBS K-XOHT.
iMd by D. UeFarian
Fio. 31.
S feet. A sraphlte electrode (3, FU;. 81) !■
od thelaro etwtrodea enoliMed irithinB iMel
.□(mereunr. The taeder valve
B-vlee of te«diD| the tube eome
llMot F/lOi
lat which ia used upb.,
^t throuah the tube. All
iMi or boibe thnu^ which ourrent pawee
■in a hicber vmoniini due to eolidlfioanoa or
1 of tha raridml v>Ht. Thm ia ■ untied
■nt Oils mm. of mereniT. at wUoh the oon-
I a "—"■"""' and thd sraataat eanent will
pimure at aunmiun li^t effieieney ii. how-
& bMier. I.e.. 0.1 to all mm., henn the
> ia adjnatad to maiotaln tbepmaureat this
I H doM aa follows:
nine (8. Pif . 31 ) 1> eonent
I bo™ Wba (0) which oonni
the tifbtins
oemiry the
igplaoer (7) whieh
lid coil (S) whieh
the fifhtinff tube fallfl the eoixductivity and
fy to fall Ip^eiTI^ <
, j^_ „ eappGed to the feeder valve. Altera yja 89
t puruua earboD phic and find^ Lta way to the
bavlhe aetion eontinaiDK until the pnaaun i* brouaht back to
be eaiboD plug
V
566
ELECTBIC LIGHTING.
normal. The device is capable of very close adjustment. The tranafoiiBa
ia usually supplied with alternating current at 220 volts and raises Ail
voltage to 2(XX) volts or more, depending on the length of the tube.
The tube is self-starting and responds at full brilBaney instantly upOB
closing the switch.
The intensity may be made anything desired from 5 to 50
per lineal foot, the normal commercial brilliancy being 12 candle-po
toot, the radiation being uniform in all directions in planes perpenc
to the axis of the tube. The efficiency is said to vary from 1.4 to 2
per candle-power depending upon the length of tube, « the light intensiQlw
etc., and is not affected by variation of supply voltage. See Fig. 33.
In practice, tubes are said to have a life of from 3000 to 5000 hours aad
then can be renewed at small cost. The efficiency is said to remain
after the first 50 hours' run.
BO
7ft IM m- 160 Uf ,»o
UNOTM OFTUM IN
Fig. 83.
The color depends upon the gas supplied to the feeder vabre. It v
exactly the same shade of white diffuaea aayUgfU when fed with pure oitn^
gen, and orange-pink when fed with air.
The intrinsic brilliancy is claimed to be the lowest of any known Ulima-
nant and therefore is extremely soft and agreeable to the eyes and doa
not require to be shaded or diffused to avoid glare but may be reflected to
obtain any distribution desired. An intensity of 0.66 candle-power per
square inch corresponds with 12 candle-power per lineal foot.
EAciency of Moor« V«l>«.
Earlv in 1907, Sharp & Millar conducted a series of teste on a Mooie
tube that had been installed in Assembly Room, No. 7, of the United
Engineering Societies Building, and reported the following results.
The tube was 176 feet long and approximately li inches diameter,
was fed with nitrogen gas, and operated as a 60-cyole system.
Total watts consumed by tube system 3451
Line volts 220.3
Amperes 21.6
Volt-amperes (apparent watts) . . . , 4736
Power factor 73%
Total lumens produced 17,400
Efficiency as light producer — lumens per watt .... 5.5
Lumens per apparent watt 3.68
Watts per equivalent mean spherical candle-power ... 2.i9
Apparent watts per equivalent mean spheneal candl»>
power 8.41
It
THE MOORE VACUUM TUBE LIQHT.
567
'Sham inetaUation of Moore Tube waa oombared with three installationa
'of ineandeeoent carbon filament lamps in the same room; they were ae
foilowa:
No. 1.
Installatton
' Moore Tube.
TnBtBllation No. 2,
Itunps under Tube.
Installation No. 3
I^impe in Reetanslee.
Installation No. 4
Lamps with Reflectors.
-Moore Tube, 176 feet long, running around the
room close to the cove.
— One hundred 16>e.p. lamps placed horiiontallv
5 inches beneath the tube, and equally spaced.
. — Eighty-four 16-oandle-power lamps bare, ar-
ranged in equal rectangles, 15 teet, 4 inches,
above the floor.
. — Same as No. 3, except that the lamps were
equipped with Holophaae distributing refleo-
tori No. 7381.
t«a«lta of the Coatpttnfttire Veaie.
Instal-
lation
Num.ber.
Number
of
Lamps.
Mean
Horison-
tal c.p.
Mean
Spherical
c.p.
Watts per
Horison-
tal c.p.
Watts per
Spherical
c.p.
Total
Watts.
1
2
3
4
1
100
84
84
(per ft.)
8.1
13.82
11.31
11.11
(per ft.)
7.9
11.41
9.33
9.16
2.39
3.48
4.26
4.32
•
2.48
4.21
5.16
5.23
3451
4810
4040
4027
■
]
Illumination Values
Efficiency Values.
H
root uandies.
Lamp.
Gross.
Net.
Ir
mum.
Mini-
mum.
Mean.
Vari-
ation.
Lumens
Watt.
Lumens
Effective
per Watt.
Lumens
Effective
per Lumen
Generated.
1
2
3
4
4.38
3.27
2.10
2.61
3.18
2.28
1.16
1.26
3.69
2.69
1.71
1.97
16.2%
18.4
27.5
31.7
5.05
2.98
2.44
2.40
2.08
1.08
0.82
0.95
41.2%
36.2
33.6
39.6
The above table showe that, witii regard to the uniformity of the dis-
tribation i^ illumination, the Moore Tube performance was very good, but
that the performance of the incandescent lamps arranged beneath the tube
was practically the same.
' A disadvantage from which the Moore Tube suffers is that it flickers in
onlson with the alternating current which feeds it. On 60-cycle current
this flickering is iK>t noticeable, except when the eye is moved rapidly or
when an object is moved rapidly before the eye. It then becomes notice-
able, and for certain work is very objectionable. It, however, has the great
advantacB of throwing a very soft light of low intrinsic brilliancy, which
does not need to be diminished by olffusing glasses in order to make it
entirely bearable for the eye. The test shows that its efficiencv, while not
•quailing that of the tungsten lamp, is about equal to that of the tantalum
wmpw and greater than that of any o^er incandescent lamp.
{
568
ELECTRIG IJOHTINQ.
AMC MJLBO^ AJr]>
lO
Rbvisbd bt J. H. Hai^lbsro, ConauUing Bnoincer.
Tea arc lamo is an deetrioal apparatus in which an electric ara
and maintainea between two or more electrodes, givins a brilliant illi
nation, the color, and intensity of which depends upon the oompoMi
and diameter of the electrodes, the kind of current supplied and the —
consumed.
Owing to the extremely high temperature of the eleetrie are fvi
between 2500 and 4000° C.) the electrodes must have a hig^ volatiKaat
Eint in order to obtain sufficient life from one set of them to make
np practical. Caibon has been found to be the most suitable material :
the purpose. A pair of carbon electrodes of proper diameter to nuuntaia
steady arc with a given current strength and voltage drop, will ooi
itpproximate rate of 1.25 inches per hour in open arc lampe. aj
at the approximate rate of 1.25 inches per hour in open arc lampe. and .1^
inch per hour in those of the enclosed type. If cross section of the
be too large, the arc crater will cover a comparatively small part of
carbon point. The shifting of the arc moves the crater to a oooler
which makes a considerable change in the resistance of the aao.
change is so rapid that the lamp mechanism cannot compensate for it
quicldy as required, hence a variation in the candle-power of the
which makes the use of carbons of large diameter impractical. With
bons of too small cross section, the candle>power is greater, and the are
very steady, but the life of the electrodes is too short lor practical
In Europe, the practice is to use carbons of comparatively small
of extra length, or to trim often in older to secure peifeeUv steady ill
nation at maximum efficiency. In the United States, the piaetiee
been to use carbons of larger diameter, giving longer life with one trim
limiting the length of the carbon to about twelve indies, thereby red
the cost of the carbons and labor required, but sacrificing steadinea
illumination and efficiency.
Developments have been made in the manufacture of cariKma for
flaming arc for open arc lamps, which have more than doubled their
denoy, and give four times the effidency of the enclosed arc. Tht in
duetion of arc lamps with dectrodes placed points downward at an
to each other (instead of one above the other as in the old style of lamp]
makes it possible to use carbons over twenty-four inches long, if n<
without making the lamp impracticably long.
The metallic oxide electrode has abo bMn successfully developed,
open arc lamps commonly known as "magnetite" lamps nave been put
the market and show a marked increase in effidency over that of
enclosed arc.
There are seven governing faoton to be considered by the dedgner of ant
lamps:
1. Steadiness of the light.
2. Watt consumption per useful candle-power.
3. Maximum practical length of the dectrodes.
4. Length of fife with one trim.
5. Cost of the dectrodes.
6. Cost and rdiabiiity of the lamp.
7. Adaptability of lamp to the several systems of dectrieal diatributaoa|
in general use.
Op«M Area, ]>tr«€t CvrreBtt
Ordinary open are lamp with carbon dectrodes. Series or multtpkl
6 to 10 amperes, 45 to 60 volts at terminals for constant current acne"'
fiO to 60 volts at terminals for constant potential multiple or multiple sent
operation. Life of carbons, 10 to 14 hours, approximatdy .6 watt ptfj
candle-power, dear globe. j
"Magnetite" arc lamp with metallic oxide dectrodes in series only on
ABC LAMPS AND ARC LIGHTING. 569
iteat earrent, 4 Mnperes, 75 to 80 volts at terminali. Life of dee-
les, 150 boura, approzimatflly .7 watt per oandle-^wer, dear globe.
'naminc" u« lamp, carbon electrodes with chemical core filUng. Seriee
multipKe, 8 to 12 amperes, 45 to 50 volts at terminals for constant current
50 to 60 volts at terminals for constant potential multiple or mul-
enn operation. life of carbons. 10 to 18 hours, approzmiatdy .22
kt per oandle-power yellow flame, approzimatdy 3 watt per oancUe-
wrfaita flame, dear i^be.
Oidinsuy open arc lamp with carbon dectrodes in multiple only, 10 to 16
iariBperes, 40 volts at termuals — minimum practical frequency — 60 cycles.
'IlFe of carbons 7i to 12 hours, approximatdy .75 watt per candle-power.
rciobe.
"Flaminc" are lamp carbon dectrodes with chemical core filling. Series
«r multiple. 10 to 14 amperes, 40 to 45 volts at terminals for constant current
ariea; 5o to GO vcdts at terminals for constant potential multiple or multiple
■kies operation; minimum practical frequency, 25 cydes. Life of carbons.
ID to 16 hours, approximately :25 watt per candle-power, yellow flame;
sppsoTimately 3Z watt per candle-power, white flame with dear globe.
Wm^mmm^k Arcs, IMrect C«rremt i
Ordinary andoeed arc lamp with carbon dectrodes. Series or multiple,
{ to 7i amperes, 75 to 85 volts at terminals for constant current senes;
200 to 250 volts at terminals for constant potential multiple or multiple
series operation. Life of carbons, 75 to 150 hours, approximately 1 watt
|Nr canole-power. dear ^obes.
Enclosed arc lamp with indined dectrodes d pure carbon. Multiple
pperatioa, 8 to 10 amperes, 100 to 120 volts at terminals. Life of carbons,
90 bouts, approximately .45 watt per candle-power, dear globe.
AltcniiatlMr Cmrresit t
Ordinary endoeed arc lamp with carbon electrodes. Series or multiple, 4
to 7| ampeiea. 75 to 85 volts at terminals for constant current series; 100 to
120 volts at terminals for constant xx>tential multiple, or multiple series
operation; minimum practical frequency, 40 cycles. Life of carbons, 70 to
too hours, approximatdy 1.33 watts per candle-power, clear globes.
Enclosed arc lamp with inclined electrodes of pure carbon. Ifultiple
qwrataon, 10 amperes, 100 to 120 volts at terminals; minimum practical
ey, 40 cycles. Life of carbons, 20 to 25 houxv, approximatdy ,6 watt
per candle-power, dear globe.
OPSir ARC X.AMPS.
_* requires for most successful results hi^-grade
earbooe, oored positive and solid or cored negative. LampB wiw either
rinmt or di€Ferential carbon feed-control, operate 2 in series on 100 to 125
ralta, direet-corrent dreuits with any current adjustment between 6 and
13 amperas. The are should be set for an average of 42 volts, and suffident
pwistanee must be introduoed in series with each pair of lamps to make up
Lbe ditferenoe between the required lamp voltage and the voltage of the
iDppiy dreoit. Attempts have been made to operate from 4 to 10 lamps
n Btnem on constant potential circuits of 200 to 600 volts, but with only
^artxal sueoess.
On alternating current the low-tension open-arc lamp requires a very
imAl grade of carbon both cored and of the same diameter ana length.
1^ following are the best dimendons for the carbons:
Tea amperes. 9i X i inches; 14 to 16 amperes, 9i X I inches giving
iboat 10 to 12 boars' life.
The alternating current, open are lamp requires about 30 volts at the
ae with 35 to 40 volts at the terminals. The carbon feed is controlled by
k flioipto magpaet connected in series with the are. The lamp is, therefore,
k strictly multiple, 35 to 40-volt lamp, and requires spedal means for pro-
570 fiLECTRIC UGHTING.
viding this pressure. For large inataUations a special traiuformer _ _
ing to about 35 volts is used. Where only a few lamps are requiied
small ("economy") single-ooil transformer with taps for one, t^vo, or
lamps IS used.
The illumination from the open are, altematiitf current lamp has
sen altogether satisfactory, mostly on account otlow oandle^po^
Sled a
been
sive amount of violet rays, and noise.
The low-tonsion, open arc lamp has not been in general use in the Units^
States since 1900, having been supereeded by that of the encdoeed tym.
In Europe, however, this form of lamp has been in use until quite reeaiaff,
as the enclosed arc was never very generally adopted there. The flamiiv
arc lamp is now, however, replacing many of the other forms of open ai«
lamps.
Hlrli-Teiieiov ILmmxp requires ordinary grade carbons, both at wbUk
may be solid, although in some cases it is of advantage to use a cored po4»
tive. The usual carbon dimensions are, for 6 to 7 amperes, 12 X A mdk
upper and 7 X A i°cb lower; and for 0 to 10 amperes, 12 X i ineh uppv
and 7 X h inch lower. This is a strictly constant current series hut^
operating any number in series up to the capacity of the generator. Odd*
stent current series arc generators have been built for singfe eircuits of 175
to 200 lamps, requiring as much as 10,000 volts. Later practice is to boid
generators for 100 to 150 lamps, but bringing out leads tor several circoiti^
tnus reducing the maximum [totential of the system and still seeoring the
benefits due to the use of fewer and larger generators of higher efficiency.
The brush multi-circuit arc generators, as Duilt by the General Bleetna
Company, represent the latest development in large aro-Kghting units fbf-
direct current series lighting.
The high-tonsion lamp has either shunt or dififerential carbon feel and ii
built for 6.8 amperes with 42 to 45 volts at the arc, usually rated at 1200
nominal candle-power; and for 9.0 amperes with 45 to 50 volts at the are,
rated at 2000 nominal candle-power. The high-tension series open are
lamp, operating on direct-current arc generators was the standard for stred
lighting in the United States until about 1900, since which time many of
them have been replaced by enclosed arc lamps.
Vli« '' ]ilac>>ecit« *' Arc Mtaaip is of the hi^- tension, direot-euirsnt
open-arc type metallic oxide electrodes. It is especially designed for outdoor
lighting, to which it is limited on account oi the fumes and heavy deposit
from the electrodes. The positive electrode is made of pure copper, or inMa
copper in combination with small non-conducting particles. Another
form of positive electrode for this lamp is made of convoluted stripe <i
laminatea copper and iron, and is 1 inch long by i inch diametor. The nMe-
tive electrode consists of a steel tube, tightly packed with a fine powwi:
the principal ingredients of which are: oxide of iron (magnetite), oxide of
titanium and oxide of chromium. The steel tube serves as a conductor for
the current to the crattt* and is also the holder of the oxide powder, makrtf
a binder unnecessary. The oxide of iron gives conduetivity to the fused
mixture when cold, the other oxides being conductors only when hot. The
titanium oxide has the property of rendering the arc luminous. Hie oxide
ck chromium prevents too rapid consumption, thus giving long Hfe to tbe
electrode. . ^
Unlike all other arc lamps the maximum illumination in the "Magnetite
lamp comes from the ne^tive end of the are. The General Eleetnc Oo^
pany have designed their "Magnetito'* lamp with the negative deckrode
below the positive, while the Westinghouse Electric 4e Blanufacturing Ooo"
pany place the negative electrode above in their metallic oxide lamp. Ad-
vantages are claimed for both forms of construction. An electrode havtef
12 inches to bum will last about 150 to 176 hours. The positive eleetroda
although only one inch long, would last much longer, but is generally renewed
at each trimming.
The metallic arc electrodes, being chiefly composed of oxides of iron
titanium and chromium, do not bum away to an invisible gas, as does s
carbon stick, but are volatilised bodily, and the vapors instantly oondetos
on leaving the arc to a fluffy reddish soot. This soot if allowed to cotss
in contact with the reflectors or globes will smudge them badly in a few
minutes. It will also condense and settle on the electrodes, hiding the hffi^
so special means are introduced for carrsrine it off. Air currents are
caused to circulate past the arc, under the reflector and within the gjkwe
^
ABC LAMPS AND ARC UGHTINQ.
671
■ neh a maniMr that all soot deposit is carried up through a chimney in
pi enter of the lamp and out in the open air. The sucoeas of the " lias*
plito" lamp depends to a lazse extent upon the creation of air ourreota
Hod LmniDOQs
fright Bellootioii
B Luminous
NouLut&Iiioas
Brishi
FM.M. A. Metallic Arc, with negative below. B. CSandle flame.
C. Metallic Arc, with negative below.
within the globe, and it has been a great problem to get sufficient natural
sod to control it with the short chimney permissible in an arc
Starting
^ststonc9
Fio. 35. General Electric Co.'s Magnetic Arc Lamp.
The ** Magnetite" lamp has a white dassling arc of great intensity, but
n^uer small volume. The candle-power is greatest at 10 degrees to 20
B^grees bdow the center line of the arc. This fact makes it especially
■natlT iDGmnnt its
lisnc;. Bsvenl mctbods of Munbining mMallle nlta with U
b«eD trifldt but creat diffioutty hu b«aa eTpcriennd in sMUnoc ■ aoinjna
wbich would evcpiually iutomipt tbs service o[ tbs Ump. Huso Bnn>
of Nihom. Gemuny, hM gscuiwl & number □[ patmU od spesul aketndB
tor »n lamps. sompoHd of "an intinut« mixture" vl oubon uid mouUt
ulu or DiM&lloid«, u Cildum, io»«nB>iooi, alua, fluorspar, o- "■-- ■"-
Mr. Bramer hu bUo developed s line c^ an U^^or his ipedal
It has been found by eiqwriaDDe tbst tbe Bremei eleetrodes an
■lag formation and insure cdchI 130 . .
Tbe carbon manufaeturen appreciating the peat eommntdal Vmin •»
effimeDfv of tba flaming aro hava devriapad a hne of cored narinaa, tbed^
of vhicb consisla of carbon, the sore being made up of a mixture of pow-
dered carbon, mineral salts and a euitabia binder. This deetrod* ka
■beolutely removed tbe diffioulty from the abg formation with Uie BnMi
electrode, allowing the useof very simple an iampa amnged U> feed theri•^
tn^tt with poinle downward at an an^ towards cadi other. Ckrtfa
that of tbe ordinary iaoandncenC Ump. iCrea tima Ukat olSe onliiiwl
open arc, and six (imea thalof the enclcMd are. Theintrinrie brilHucri*
the are Same Is about one-tbird that of its poriti' ' -—
Tbe candle-power dialribution in th- " — ■
lows: Positive orat«r, 20 p«f coat; r
flame. 75 per cent.
Bjr placing tbe carbon ixilnis downwartl. m
obtained from the oraten without inlerferenoa ai
naitive and ns^tive cntM- <
arc is apprvximatdr ■■ M-
ntar, S par cent; and thaMt
ARC LAUPS AND ABC LIOUTING.
b nttinlsiiMd too
."Sit
s lylp nBrbon NpantloB, tba
ivB uid lotcrlcra wmawlut with
tfluly mt vottui
By ntaoa 01 tt
Lt«n. Tbs Somioc are bcaoiiMi luxtoady mt vottuia
IS BuiTMit. uid 4S on dinct OQtnnt. By rcMoa 01 UM
tha loi>«r and o( Um two ■leatn>d«^ with poinla down-
...._ .!> provida mauu for tuudtaiiiiiic It ». .
iitrof the pointa, u othui win the beet of the flune wilTinduoa en
d dnft which will eenr the bto up between the deotroda, (oob
the enten end prevcntin) proper sombuatioD. It ia well koowa
■a rfeetiio ue Duy be oontnriled by nucnatio Unea at toroe. Thk
Toi200>^/C A.C. Sot/rca
Fm. ar. IMksrun Cooneotions G. E. Ifiiciietite Are Liihtinc Syitem.
■Kindiila haa been taken adrantaEe of in the f
^_i _;.u . -... — J — „ o^.. ii„i„. tha in
' « if b3d ID a
e eomplioeted mechsnienit
---_ ■iwtfcfwiiwj the ait) lencth oonatant. iB«L ,._. .^ .^-^ -—
ibe lersa vn Seme navinc nn mna of about \ inchfv BquAre. furauhea
It PIT etot sit the Ulumiaetioa. This pest KinKus of lisht is loroed down
tewHidi the ooiter flf the ciobet which la praferabLy [nad« of Light atabaiter
lliH, miiiiiMlliii It M k U^ intODdt]' end without sbadowa. The ilium-
C
r
574 ELECTRIC LIGHTINO.
IxiAtioii from the flaming are lamp with H|^t alabaster i^obe is
uniform in all directiona, beginning about 10 de^pees above the
oenter line of the arc. The downward illumination is slighty g
to the Ught from the oraters, but as the flame throws the greater part
Ught in the horisontal direotion, the praotioal result is unitonn iUumh
of the entire globe. Flaming are lamps should be hung high, 20 to 6ft
above the floor or street level, excepting for advertising purposes wfaers 1
may be hung lower. If the lamps are placed 50 feet above the floor sad
feet apart, a practically constant and unifonn illumination of great in
will be the result.
The OoaetMst PotemtlAl ]>. C Flfsasteff Arc KAHip imum
to 60 volts at the terminab and is adjusted for 46 volts at the arc. ^lelM
operates in multiple on 60 to 00 volts, two lamps in series "on 100 to T
volts, four on 250 volts, ten on 500 volts, twelve on 600 volts, and fiftea
750 volts. When more than two lam|M are to operate in series, an est
automatic out-out with equalising resistance must be put in multiple
each lamp to protect it against excessive voltage. The standard »HHittt0
is 10 to 12; the positive carbon is ,10, and the nentive 9 mm. in dismettt.
A pair of carbons 500 mm. long give 12 hours' me outdoors and 13 to 14
hours indoors; the 600 mm. carbons give 16 hours outdoon and 18 hooi
indoors.
The C«H«taB« Potential A. C. FlaMtac Ave Mmm^p reqmni
50 to 60 volts at the terminals and is adjusted for 38 to 40 volts at thssia
One lamp operates in multiple on 50 to 60 volts, or two in series on 100 to 129
volt drouits. When one lamp is to operate in multiple on 100 to 12Q'VQtt
oircuitj a small auto-transformer is required to reduce the voltags to fiO or
55. Similar auto-coils should be used when lamps operate on 200 to 4fl&
volt systems. When a large number of lamps are to be used a regtdar tlirw*
wire system can be installed with 55 volts between each outside wire Md
the center wire. One large transformer reducing from the pdaaaty poMr ■
tial to 110 — 55 volt three- wire system — shoula be installed, allowini m J
flaming arc lamp to operate in multiple on 55 volts without loss and ests^
expense for separate auto-transformefs or other compensaton. The fl*^ 1
ing arc lamp will operate successfully on any frequency from 25 to 1#-
cydes. Below 40 cydes, lamps should always be operated in moltipleaB
55 volts. The standard current adjustment is 12 amperes. Hie ositatf
are both 9 mm. in diameter. The 500 mm. earbon gives 10 to 11 hoM,
outdoors and 11 to 12 hours indoors. Oarbons 600 mm. long give 13 to If
hours outdoors and 14 to 16 hours indoors. The alternating current nap
is practically noisdeas and sives a very steady illumination. The effi^eMf ,
of the alternating current flaming arc lamp on constant potential ii vMm
80 per cent and the power factor about 90 per cent, ^e effidency tff
quality of the illumination compares favorably with thatctf the direct eurrflii
lamp, which is an important pomt in favor of the flaming arc lamp for alt>^
nating current drcuits.
Tlie GoBstaitt D. G. S«rl«e XlttBilay Af« XiABBVreqiiireB 46 ▼«■
at its terminals and is adjusted for 43 volts at the arc. The lamp ii *
tical in construction witB the direct current constant potential lamp, M
rcNquires no resistance in series with the arc. An automatic cut-oot is uiM
with each lamp to shunt the current in case the carbons should stick orW
prematurdy consumed. The lamp can be operated in series on the regoV
9.6 ampere arc dynamos used for uie ordinary hip^tension open are IsfflP^
The mercury arc rectifiers with constant current transformers can eho W
used to supply current for the direct current flaming arc lamp. As a ntttr
of fact, it may be operated in series with the old style, high-tension, opg>*g
himp. The sise and life of the carbons is the same as for the direct comn,
constant potential lamp. ^i
VlM CoMstttBt A. O. 0eTl«« risuMlar -dLvo l4Mip reqiiii« *
volts at the terminals and is adjusted for 38 volts at the are. The ooiat>?
current lamp is practically the same as that for constant potential, t>«t '
provided with an automatic out-out to shunt the current. The hunpoM|
ates with 10 to 12 amperes in series on constant current drouits controWB
bv constant current transformers or automatic reactive coils. As pi*)*"!
^ alternating current series drcuits for street lighting carry only 4 to 7t
^ amperes, it is necessary to install with each lamp on such drcuits s flo*"
senes transformer or series auto-coil which wiU deliver from its seecjodsiT
10 to 12 amperes at 40 volts to the lamp. ' In oonjunotion with series TuBf
ENCLOSED ARC LAMPS.
576
ting on the same oirociit, the entire street lifl^ting field
fumisning both large and small units from the same wires.
and ufe of the carbon is the same as for the constant potential
current lamp.
io 600 watt direct current flaming are lamp, with yellow flame
approximately 2700 mean spherical candle-power; white
give about 2000 candle-power.
_ power of the alternating current flaming arc lamp is about
las than that pven for the direct current lamp of the same
always
a and focusing lamps for theatrical use and
ving. etc., take large and varied Quantities of current, as
.t connected across the terminals of constant potential cir-
a regulating resistance in series with the lamp. The General
~l)any state in one of thmr bulletins the following as being the
oarrents taken by the different sisee of searchlights:
Dujc. OF Pbojkctob.
12 inch
18 "
24
30
36
60
Ampbrbs.
18 to
20
30"
35
60"
60
76"
OO
90"
100
125"
150
ElVCHMMiSl^ ARC X.AMPft.
foand that by eneloeing the arc in a small globe, more or less
_ air-tight conditions, combustion of the carbons is practically
fisving no dust, and takes place at a slow rate, burmng with a
^ carbon 75 to 100 hours without attention. The enclosed arc
ipoperly maintained below 65 volts, and 70 to 75 volts is the usual
^ * for alternating current lamps, and 75 to 85 for the direct
The n»T™'"""> current is 3 and the maximum for enclosed
are. low amperage and enclosing globe all tend to lower the
efficiency of the «iclosed arc lamp, but notwithstanding this
Bded most di the open arc lamps for general illumination. The
the carbon has greatly reduced the cost of trimming and the
tfboo renewals. It permits the use oi very simple mechanism,
a dutch which operates directly on the carbon. Enclosed arc
made for all commercial circuits.
P»teatl«a D* €• Sacloa«d Arc I<anap requires 100 to
\ St the terminals with 75 to 160 volte at the arc. The minimum
is 2\ and the maximiun is 6. The 2k to 4-ampere lamps use
ii eubons. The 5 to dntmpere lamps use {% to i-inch carbons,
bog, giving 75 to 150 houns life. Each lamp is fitted with a
ooil, and is a complete unit for multiple connection on 100 to
vith 75 to 85 volts at the arc, or on 200 to 250 volts with 140 to
et the are. The oonstant potential lamp is controlled by a series
If the lamp is provided with differential clutch controlling ma^-
■atie cut-out imd equalising resistance, it can be connected m
eoosteat potential circuits, as follows: 2 on 220 volts, 5 on 500
' 6 OB 600 volts.
teattol A. C. Sncloa«d Arc I^amp requires 100
Its at the terminals, and is adjusted for 70 to 80 volts at the arc.
lage mavbe anywhere between 4 and 7}. The alternating current
poteatiai lamp is not operated in series. The power factor of the
woat 70 per cent. The minimum frequency ^ving satisfactory
"^ is 50 cycles; and the maximum frequency, m general u.se, for
I style of lamp is built, is 140 cycles. The carbons are usually
^g X I to 9 inch in diameter and give from 65 to 100 hours'
•Itemating current constant potential lamps are to operate on
576
ELECTRIC LIGHTING.
▼oltageB above 125, an auto^tranafonner or other oonverter for redu.
the voltage should be used. A reactive ooil is also put in the top of
alternating current lamp.
Co— tiaat D. C. Sorlea KMcloned Are lABsp requires 75 to 80 '
at the terminals. The arc is set for 73 to 78 volts. The amperage is 1 _
5 and 7. depending upon the candle-power desired. The lamp oas diinv
tial feed and is provided with automatic out-out to shunt the current, ff
carbon sticks or is consumed. The lamps operate in series on any eopfll
current source of supply. The carbon is 12 X i inch and lasts about
hours.
C^matmmt A. C. Aeiitti Baeloaed Ave lABsp reauiT«a 75 t^J
volts at the terminals. The arc is set for 72 to 77 volts. The
amperage is 4 and the maximum is 7^. The feed control may be eil
shunt or differential. The carbon is 10 X i inch and lasts 75 to 100 ~
Ekich lamp has an automatic cut-out. The lamps operate in serif
stant current drouits, usually controlled by constant current tranafc
or automatic reactive coils. The eflBiciency of a complete system, incl
transformer and lamps, is about 85 per oent, and the power nctor is beti
70 and 80 per oent at full load. The system operates on any frequi
from 50 to 140 cycles.
Metkods of ltog:«l«tloB Ib Arc IiaBipa may be dasaified
follows:
Carbons lifted or separated by direct or main magnet; shunt
acting on a variable resistance to cut out the main magnet in feeding.
Carbons lifted bv main magnet as before, and shunt acting to put
main magnet (made movable) into position for feeding.
Carbons sepiarated by main magnet armature; shunt circuiting
acting to divert or shunt the magnetism of the main magnet from its
ture.
Carbons separated by main magnet and shunt acting to free the
holder, independently of the support given by the main magnet.
Carbons separated by a spring allowed to act by the main magnet lift
a wei^t which otherwise holds the spring from acting; shunt magoet
against the spring, to feed and regulate the length of are.
One carbon, generally the lower, separated by main magnet, while
other holder is released for feeding only, such feeding being under tbe
trol either of a differential system or a shunt magnet only.
Carbons separated by main magnet, which lifts the shunt and its
ture toother, while the shunt magnet armature, acting on the U
mechanism, controls the arc and feed of the carbons.
Carbon feeding mechanism independently attached to main magnet
ture and to shunt armature so as to receive opposite movements of
tion, and feed from each respectively.
Carbons separated by a feeding mechanism moved by the main
and fed by a further movement <^ said mechanism, causing rei4
turn of same under the accumulated force of both shunt and main
aotinc in the same direction.
Differential clock gear for separation and feed of carbons under cool
of the regulating magnet svstem, either simple or differential, fiome of '
older clook-work lamps embodied this prindple.
Carbons controlled by armature of a small dectric motor under oontrol
a differential field which turns the armature in one direction for
and in the other or reversed direction for feeding the carbons.
Carbons controlled by a motor running at a certain speed when the ate
of normal length, and varjring in speed when the are is too short or too loi
combined with a centrifugal governor on the shaft of the motor, acting
variations of speed to gear motor shaft to screw carbons together or a]
as needed to maintain the normal arc. Hiis medianism has beeti
to large arc lamps, such as naval search lii^ts, and has the advantage
great positiveness, and an ability to handle heavy mechanism.
There are also a condderable number of modifications of these prindi
or
ENCLOSED ARC LAMPS. 577
TMta for Ave Uffht
jWw Open Area,
Tlie ■atisfMtonr working of aro lamps la largely dependent upon the
ty of the carbons need. If carbons are made of Impure materials, they
^epttrad In its preliminarr stages, the carbons will have either too short a
^llfe, tbroqgh giyiug a good quantity and qualitr of light, or will have good
Ufe, bat wHl bum with an excessire amount of riolet rays, hence with poor
ttlgmlnation.
For indoor use a iree-buming. nnooated carbon of medium life should
fee used, so as togire a £ood quality and quantity of light, if longer life is
desired they may be lightly coated with copper without materially interfer-
ing with the light. (About 1^ lbs. to 2 lbs. of copper per thousand, f^" x V2f*
carbons, and a half pound more for f x I7f' carbons will give gooa results,
increasing the life from an hour to an hour and a half.)
F6r ont-door use a more refractory burning carbon may be used to advan-
tage, glring a longer life, as the quality of the light is not so important.
Copper-coated carbons are^also usually employed, and may have about four
rDonds ot copper per thousand for f^'' x V2r carbons, and flTe pounds for
'' X V3f. Other sizes in proportion.
All plain molded carbons, and most of the forced carbons, deposit dust
when Domed in the open arc. Those depositing the most dust give out the
moat light, but have the least life. Those depositing the least dust usually
!save the longest life, but the light is of inferior quality on account of the
increase in the proportion of violet rays.
The quality of any carbon may be verv quickly tested in any station by
using the following method, which has oeen largely employed by carbon
manoiActurers.
The important points to be determined are theranM. including the hUB-
trnff^jtumptng^ andjfaminff points, the reeiataBce, ana the life.
Ine Msiaic« is found Dy trimming a lamp with the carbons to be tested.
allowing them to bum to good points and tne lamps to become thoroughly
heated; then connect a voltmeter across the lamp terminals, and very
slowly and steadily depress the upper carbon until the lamp hisses, when
the voltage will make a sodden drop. This Is called the HtsslBflr-Polnt.
and varies according to the temper of the carbon. It should be between 40
and 46 volts — preferably 42 voits. Then lengthen the arc somewhat, and
allow it to become longer by the burning away of the carbons. Presently
the arc will make small jumps or sputters out of the crater in the upper
carbon. This is the J'aiispiBiir*l^olBt, and should be not less than 5s or
60 volts. Let the arc sttU increase in length, carefully watchingthe volt-
age* and in most carbons there will soon be a decided flaming. This is the
nssBilBir^P«lBt- This should not be less than 02 to 66 volts. Very im-
pure carbons will commence to Jump and flame almost as soon as the volt-
age Is raised above the hlssing-point, and even the hissing-point in such
eases is very irregular and difDcult to flnd. The Range is important as
heing a practical test of the purify of the material used in the manufacture
of the carbon, an increase of a quarter of one per cent of impurity making
a Tery decided reduction in the extent of the Range. The hisslnff-point
ahoQ]dbe4or6volt8below the normal adjustment of the lamp to Insure
steady burning.
JB«eiatsuM«. — The resistance is measured on an ordinary Wheatstone
bridge. Care must be taken that the contact points go slightly into the
earbon. A i/' x 12^' plain carbon should have a resistance of between .16
and .23 ohms, and y x 12^' between .14 and .18 ohms. ^' x 12^^ carbons coated
with three pounds of copper per thousand, have a resistance between .06 and
jOOohms, and ^' x 12^-' with four pounds of copper between .04 and .06 ohms.
MJkf^m — The life of a carbon is most easily tested by consuming it
entirely in the lamp, observing, of course, the current and average voltage
during the entire time. A very quick and accurate comparative test of dif-
ferent carbons can be made, however, by burning the carbons to good points,
then weighing them, and let them burn one hour, then weigh them again.
The amonntbumed bv both upper and lower carbons bIiows the rate of
eonaumption which wiu accurately indicate the comparative merits of the
rbons tested as to life.
578
ELECTRIC UGHTINO.
To oalottUte the life from a burning test of one hour, l)oth carbons shodd
be first weighed, the upper carbon broken off to a 7-inch length, in order to |
make the test at the average point of burning, and with the lower oarino.
burned to flood points, weii^ed again, and after burning one hour in a
lamp that has already been warmed up, taken out and wetriied. The
amount of two carbons 12 inches long consumed in a complete Uxe-tast is 63
per cent of the combined weight of both upper and lower carbons, llief^
fore 63 per cent of the weisht of the two carbons, divided by the rate per
hour obtained as above, will give the life approximately.
l^v*i« — The dust from burning carbons can be collected in the glob^ or
better, in a paper bag suspendea below the lamp. In an ordinary pudD
molded carbon this dust amounts to 4 per cent of the weight of the upi^
carbon. A variation below this amount will indicate good life, but inferior
light. An excessive amount of dust would show a short life, but ueuaUy ■
good quantity and qiuility of li|^t. Coating a carbon with copper eUmiaatsi
this deposit of dust entirely.
Carbons for oiolosed arcs can be very conveniently tested as to their rel-
ative values in an open arc lamp as described above. As their diam^en
regulate the admission of air to the inclosing globe, thus greatly affecting
their life, they should be oarefulhr measurea with micrometer calipen. A
greater variation than .005 inch from the required diameter should not be
permitted. The deposit on the inside of the inclosing i^obe is caused by
impurities, prindpaUy in the core. The relative injurious amount of this
deposit can be measured by carefully taking the globes off the lamps after
burning, and measuring the amount of light absorbed by them with an
ordinary photometer, using an incandescent lamp as a source of B^t, and
cutting the light down by means of a hole in a screen so that it will peas
through the part of the globe to be measured. Twice the light so measured
through the globe, divided by the amount coming through the unobstructed
hole, will fdve the per cent of the light transmitted throui^ the s^be friMn
the arc. That carbon whose globe absorbs the least amount of n^t is, of
course, the most desirable.
The resistance of forced carbons, whether cored or solid, used in inclosed
arc lamps, is very important. Carbons of hi^ resistance are difficult to
volatilise, and hence there \b trouble in establishing the arc iriiere wnaaH
currents are used, and in case of any interruption in refistablishing it after-
wards. This IB especially true of carbons used in alternating arcs, and of
cored carbons. The resistance of forced carbons is usually much hifi^er
than that of molded, ranging from two to four times as much. This will
undoubtedly be corrected wnen the manufacturers become more familiar
with the requirements. The lower the resistance the better the quality of
the light and the operation of the lamp.
Stxea of Carbon* for Arc timtmpm.
Open Arcs.
Continuous Current.
Upper.
Lower.
6.8 amperes
9.6 •'
9.6 ••
9 . 6 amperes *
9.6 "
12 in. X A in.
12 " X i ••
12 " X i ••
12 in. X A in. X i in.
llf" X i " XI ••
7 in. X A in.
7 " X I "
7 •• X 1 "
61 in. X A in. X I in.
ri " X ♦ " XI ••
Alternating Current.
15 amperes
9i in. X 1 in. | 9i in. X i in.
Enclosed Arcs.
5 amperes
3 amperes
Continuous Current.
12 in.
12 •*
X^in.
X I ••
5i in.
6 "
xl"
* These are elliptical in cross section, for higher candle-power and k»Qger
burning. ,
ENCLOSED ABC LAUPS.
579
for ft««>«IUIrlt( PraJ««t*nfc
(Golttinbia or Hardtmuth or Schmeltser.)
Sae of Iwnp.
Potttiv«. Cored.
Nogative. Cored or
Solid.
9 inch
5i in. X 1 in.
H
in. X A in.
13
•1
6 " X 1 -
4i
"X i "
18
M
8J " X }|"
"X 1 "
24
M
12 "XI "
"X f "
30
M
12 " X H "
"X i "
36
••
12 " X IJ "
"XI "
48
M
15 •• XIU"
12
" XI ft"
60
• 1
15 " X2 "
12
" X 1 1 "
'■■■ieBd««l for AntOMiatlc AMd HaM«l-Feed
Continnons Current.
Amperes.
PoeitiTe. Cored.
Negative. Solid.
6 to 10
10 •• 18
18 «- 20
2( " 30
6 in. X A Jn-
6 •• X f "
6 •♦ X f "
6 " X 1 "
6 in. X ft in.
« ** X "
6 " X *'
6 " X J " .
Alternating Current.
6 to 10
10 " 18
18 *' 20
2S " 30
6 in. X ft in.
6 " X I ♦*
6 " X t "
6 " X 1 "
Same m for Positive.
CaadI««power of Arc I^aaipa.
The candle-power of an arc lamp is one of the most troublesome things to
determine in all electrical engineering ; the rariations being great the arc
unsteady, and the implements for \ise In such determination being so liable
to error. Again, what is the eandle*power of an arc lamp, or rather, what
is the meaning of the term ?
When the lamp was first put forward, for some reason, now in great 'ob-
scorikT, the regular 9.6 ampere lamp was called 2000 candle-power, and it
has Mways since been so called, although the word " nominal " has been
tasked on to the candle-power to indicate that it is a rating, and not an
actual measurement.
The candle-power of the arc raries with the angle to the horizon on which
the measurement is made ; in continuous current arcs the maximum can-
dle^Knrer Is at a point about 46 degrees below the horisontal if the upper
carbon is the posltiTe, and of course above the horizontal if the negative
carbon Is above.
In alternating current lamps there are two points of maximum light, one
about 60 degrees above the horisontal, and the other about the same an^e
the line, and the mean horisontal intensity also bears a greater ratio
680
ELECTRIC uasriNO.
to the mean spherical intensity than in the direct current are. In the
alternating enrrent are mnoh of the lisht is above the horizontaJ plaa^
and it is neoeMary to arrange a reflector above the arc' to throw th&t portioB
of the liffht downward.
all
•Mwer Is the mean of the eandlo-powarj
measured all over the surface of a sphere of which the arc ia the eentsi
usually about one-third of the maximum candle-power. In practice tht
spherical candle-power is seldom fully determined, but a fair approzlmatia
may be had by the following formula :
Let
Then
S = mean spherical candl^iiower,
J5r= horiaontal candle-power,
if =r candle-power at the maximum.
In a test of arc lamps in November, 1880, for the New York City Bv«sa
of Qas, Captain John Millis found the following results in his trial of ths
Thomson-Houston lamps.
The same lamp was used, but connected to the different street circait8,sll
measurements were made at 40 degrees below the horiaontal, and ^ineh
copper-plated carbons were used.
Ten readings were taken on each of four sides of the lamp when
nected to each circuit, with the following results :
Circuit No. 1.
" " 2.
" " 3.
i« •« 4
♦• " s!
Means
Caitdlb-powbb.
2072.7
1981.0
2048JS
2000.2
2067.0
2033.9
Watts.
482.88
486.10
488.23
404.40
40S.96
490.19
Mean current, amperes . 10.36
MeanvolU 47.32
The results of tests of candle-power of arc lamps at the Antwerp Bq»csl>
tion, shown in the table below, would tend to verify the above trials.
Am-
peres.
Volts.
Maxi-
mum
O.P.
Horison-
Ul G.P.
4
6
G.8
8
10
37.2
46.2
.46
46
45Ji
390
1090
1240
1£60
2070
74
168
240
334
421
Upper
Hemi-
sphere
Mean O. P.
17
63
65
70
102
Ix>wer
Hemi-
Mean
sphere.
C.P.
Mean C.P.
110
136
296
361
320
386
386
464
610
760
Watts.
W
VB
313
360
491
i^
Ai« Iflfrlit Sfllcieacj. — The light efficiency of an arc lamp ii
the ratio of ita mean npherical candle-power to the watts consumed between
the lamp terminals. »Some energy is used up in the lamp-oon trolling median-
iam, in the carbons themselves, and the remainder is used on the are. Aro
lamp efficiency is sometimes described as the ratio of the watts used in ths
aro to the watts used between the lamp terminals. This is true of the lamp
as a machine; but the first statement is the correct one, as it is li^t that it
turned out, and not watts consumed in the arc that is the object of ths
lamp, and the two depend so much on quality and adjustment of carbons,
even with the same consumption of current, as to make the latter method
erroneous.
ENCLOSED ARC LAMPS. 581
HMit mmA 'Kva^p^rmtmrm Derelopad bj the JBlectrIc
Hie temperature of the orater, or light-emitting eurfaoe. of the arc, is the
mam ai the point of volatiiijtation of carbon, and therefore constant under
CDostant atmoeph^o presBure. This temperature is variously stated by
dUUarent investigators: Dewar nves it as 6000^ C; Roeetti. the positive as
noire., and the negative 2500^ C.
The carbon in the erater is in a plastic condition during burning; and with
the same adjustment of carbons, as to length of are, the lii^t per unit of
power increases with the current.
Hiswig. flaming, and rotating of the arc are some of the defects. Hissing
is due to a short are, and was a constant accompaniment of the low poten-
tiaL high current arc so prevalent during the earlier days of arc lifting.
Flaaung and rotating in open arc lamps are due to long arcs and to unpure
csrfoons, or carbons not properlv baked.
With good carbons the length of arc, or distance between carbon tips
lor open arcs direct current, continuous current lamps, should be, for 6.S
ampere lamp, A inch; and for 0.6 or 10 ampere lamps, i^ to A inch.
ice for Ai« lA«iM •■ ConstSMt
Potential Clrcolt.
As the ordinary arc lamp takes but 45 to 60 volts, iniien used on constant
potntial dreuits of more than 50 volts, it is neceseary to introduce a cer-
tain rentance in series, in order, first, to take up part of the voltage, and
seoond, to act in a steadying capacity to the arc; in fact, until the dead
rewtanee was introduoea in series with the arc lamp on constant potential
drenita. sudi lamps were entirely unsuccessful.
Praf. EKhu Thomson says, **a certain line voltage as a minimum is abso-
lutely necessary in working arc lamps on constant potential lines, whether
thejr be open arcs or enclosed arcs. Thus two 45-volt arcs in series, with
nneored carbons like the brand known as 'National/ cannot be safely
voAed below 1 10 volts on the line without resistance m series with them.
Mora than 100 volts should, of course, be maintained for safety of the
**The tests show, also, that with a cored upper carbon, the limit is fowered
■e?enl volts on the average, and it is known that the voltage of the arcs
mav be safely reduced somewhat when cored positives are used.
It is also shown that a 76 to 80>volt enclosed arc, run upon a constant
potential line. Is stable at a considerably less line voltage than the open arc.
It would appear, also, that with either open or enclosed ares at ordinary
current strengths of from 5 to 10 amperes, the steadying resistance in the
branch is required to cause a drop of about 15 to 20 vohs, or waste energy
at the rate in watts of 15 to 20, multiplied by the amperes of current used
in the lamp.*'
Let fa EJIft.F. or difference of potential between the circuit leads.
e » E.M.F. required at arc wmp terminals.
i ■- current required by the arc lamp.
R » dead resistance to oe put in series,
r — resistance of the arc lamp burning.
r* — total resistance of dead reaistanoe + lamp.
Then
r - ^ (1)
r. - ^ (2)
R" r, -r. (3)
As the E.M.F. of most of the circuits on which lamps of this tvpo are used
n more than 100 volts, it is customarv, and in fact economically necessary,
o place two arc lamps in series, and the formula (3) then becomes,
18 — n - 2r.
582
ELECTRIC UGHTINQ.
For good lUamlnAtion, diBtuic« apart of arc lamps should nol exceed fix
times nelffht of are from ground.
For rai&oad yards, 10 ampere arc lamps 30 feet from the ground and abost
200 feet apart are found to gire good results.
The following table shows some arrangements of arc lamps in foreifi
cities:
Arc Lamps in Foreign Cities.
Amperes
per Arc.
Distance
Apart In Ft.
Height of
Are in Ft.
City of London Streets
10
115
17J
GImsow Streets
Hastuiffii Streets
Berlin Streets
10
160
18j0
10
300
18.0
15
137
96.7
Milan Streets
• • ■
80 to 100
25.0
Charing Cross Kailroad Station .
10
90
18.6
Cannon Street Railroad Stf^tlon .
16
180
36.0
St. Pancras Railroad Station . .
10
60 to 80
14.0
Central SUtion, Glasgow . .
St. Enoch's Station, Glasgow .
Edinburgh Exhibition, 136
10
75
19j5
10
90
10
88
12.0
Edinburgh ExhibiUon, 1886 . . .
16
41
184)
lAipUt Cut off hy «lobM.
Dr. Bklx..
With respect to porcelain and glass, the following table gives the general
results obtained by several experimenters on the absorption of variow
kinds of globes, especially with reference to arc lights.
Per cent.
Clear glass 10
Alabaster glass 15
Opalesoent glass 20to40
Ground glass 25to30
Opal glass 26to60
MUky glass 30to00
f^
Too much importance should not be attached to this large absoiptioD,
since it has already been shown that in most cases, so far as useful effect if
concerned, diffusion and the resulting lessening of the intrinsic brilliaacT
is cheaply bought, even at the cost of pretty heavy loss in total luminoui
radiation.
The classes of shades commonly used for incandescent lamps and pa
lights have been investigated with considerable care by Mr.'W. L. Smith.
The experiments covered more than twenty varieties of shades and re-
flectors, and both the absorption and their distribution of li^ht were inves-
tigated. One group of results obtained from 6-inch spherical i^obes, in-
tended to diffuse the light somewhat without changing its distributioD,
was as follows, giving figures comparable with those just quoted:
Per cent.
Ground glass 34.4
Prismatic glass 20.7
Opal glass 32.2
Opalescent glass 28.0
ENCLOSED ARC LAMPS. 583
The prisnuitie globe in question was of dear glass, but with prismatie
loQgiittdiiial gnx>Tes, while the opal and opalescent globes were of medium
deniity only.
Elcfied glass has considerably more absorption than any of the above,
tbe etching beimc optirally equivalent to coarse and dense grinding. Their
diffuiioii is less Eomogeneous than that given by ordinary grinding, so that
thev may fairly be said to be undesirable where efficiency has to be sen-
ooily ooDsidflced.
One trimmer oan handle the following number of lamps per day:
Walking. Riding.
Regular open double carbon street arcs .... 80 100 to 120
Msgnetite lamps 80 100 " 120
Flamingares 80 100 " 120
Enclosed arcs 50 100
TIm number of commercial lamps which one man can trim depends so
noeh upon bcal concUtions that it is not possible to give any general figu!«.
ILLUMINATING ENQINEEBINQ.
Rbvisbd by Dk. C. H. Sharp.
Thb problem of the itluminating engine^' may be stated in general Cemft
an follows: to obtain the illuminating efifeot desired in any case with the
maximum economy, having due regard to the protection of the eyes from
disagreeable or harmful effects and to arcbiteotural and asth^c oonsidef^
ations.
Illumination may be dind, coming straight from the lamps whidi thca
are visible, or indinci, as when the lamps are hidden from view by a eornice
and the illumination is due to the light reflected from a cove above.
Measurements of candle-pow^r values are horisontal, vertical and nonnal
illuminations, according to the position of the plane of refermoe, horUonUU,
vertical or normal to the light rays.
Curves of illumination have as their abscissas distances from the souree
of light measured along a horisontal line and as their ordinates intensities
of illumination. If the vertical distribution curve of the source of li^t is
Imown the corresponding illumination curves can be computed according to
the foUowing equations, in which E a the illumination, a the height of the
lamp above the plane of reference. I the distance from the {mint in questioD
to the point immediately beneath the lamp, and /^ the intensity of the
lamp at an angle ^ with the vertical
En^
Eh"
E9
fB
h* +P
IgOOB $
M +P
/^ sin B
I^k
(a» + P)i
^B^
A« + i« (A* + i»)l
/^C08»#
A«
/^ sin» •
•
w
In considering the availability of any source of lig^t due regard must h*
^ven to the proper selection of shades, reflectors, etc.. which may be used
m connection vnth it. These appurtenances serve the following purposes:
to direct the lis^t most advantageously; to diffuse the light, decreasing the
apparent specific intensity of the source and thereby saf eipiarding the eyes;
pure decoration. The efficiency of an illumination installation often
depends to a very great degree on the selection of proper auxiliaries.
The illumination on a surface is equal to the luminous flux in lumens
per unit area of the surface, e.g. the foot'-candles are equal to the lumens
per square foot. The average illumination on a plane of reference is equal
to the 'lumens through the plane divided by its area. Hence we have the
following definitions: The net efficiencjf of an illumination installation is
equal to the ratio of lumens through the horizontal plane of r^erence to the
total lumens generated by the lamps. The groits effieieney of an installation
is the ratio of the watts supplied to the lamps to the lumens on the plane of
reference.
The net efllciency depends only on the method of installing the lampsi
on the r^ectors, etc., used, and on the coefficient of reflection of the walb,
ceiling, floor and contents of the room. If we represent this avnage oo>
* The values of sin' 9 and cos* ^ are given in Table I.
684
ILLUMINATING ENGINEERING.
585
seat by ft, multiple refleotioas theoretically increase the illumination
Uifi ratio - _■■• In practice this is found to be modified by many
Boditions. A general knowledge of the value of the net efficiency to be
ivipeetod in any ease enables the illuminating engineer to form a very ready
Iflrtimate of the number of lamps required.
Table X.
a'to29
o
•
30° to 59
>«.
60*>to89».
9.
Ooe>«.
Sin»«.
30
Cos>*.
Sin* •.
60
Coe»«.
Sin*«.
0
1.0000
0000
0.6405
1250
0.1250
6495
1
0.0994
0000
31
.6299
1366
61
.1139
6690
2
.9082
0000
32
.6008
1488
62
.1035
6882
3
.9958
0001
33
.5900
1615
63
.0936
7073
4
.9029
0003
34
.5697
1749
64
.0843
7261
5
.9886
0007
35
.5498
1887
65
.0755
7444
6
.9836
0011
36
.5295
2031
66
.0673
7623
7
.9777
0018
37
.5003
2180
67
.0506
7800
8
.9712
0027
38
.4893
2334
68
.0526
7971
9
.9636
0038
39
.4693
2492
69
0460
8137
10
.9551
0052
40
.4495
2656
70
.0400
8298
11
.9458
0069
41
.4299
2824
71
.0345
8452
12
.9357
0000
42
.4103
2996
72
.0295
8604
13
.9251
0114
43
.3913
3172
73
.0250
8745
14
.9135
0142
44
.3722
3353
74
.0200
8883
15
.9011
0173
45
.3535
3535
75
.0173
9011
16
.8883
0209
46
.8353
3722
76
.0142
9135
17
.8745
0250
47
.3172
3913
77
.0114
9251
18
.8604
0295
48
.2996
4103
78
.0090
9357
19
.8452
0345
49
.2824
4299
79
.0069
9458
20
.8298
04pO
50
.265«
4495
80
.0052
9551
21
.8137
0460
51
.2492
4693
81
.0038
9636
22
.7971
0526
52
.2334
4893
82
.0027
9712
Z3
.7800
0506
53
.2180
5093
83
.0018
9777
24
.7623
0673
54
.2031
5295
84
.0011
9836
25
.7444
0755
55
.1887
5498
85
.0007
9886
26
.7261
0843
56
.1749
5697
86
.0003
9928
27
.707»
0936
67
.1616
5900
87
.0001
9958
28
.6882
1035
58
.1488
6098
88
.0000
9982
29
.6600
1139
59
.1366
6299
89
.0000
9994
* Values of k are given in Table II.
ILLUUtNATINQ BNOINEERINQ.
iowIbt the KaMMlty of tiMi niualaadaa
'-iKmA mt T«rtor- -"-'— ^ — — — ■ —■ —
eorx.<~ ~
Ima Pnrpondli
<( ^ U« Nationai Eltdrie Lamp
HoiiHUtal DIiMdm Id fmt from Potst Dlreotl; Dnder Luup tt
I.OOHS J *
|.oaise»|n e Loainaj
D !<mi04su ttkoouNu
|i!^:^
80 M
001109
-J ^
00072a
S2 M
00IM7J
U«0
OOOMl
MIS
.^
OOOSSTG
es u
3S!^S
M M
M) IS
ei 0
M 19
H 30
GO 5S
St »
jj
ID 40
ii
49 36
001801
4S M
II
IP
;oou«
tot
4>0
:i
as 40
4(0
0010S8
N3D
49 10
.<
U M
as u
»H
^
13 10
000091
II 1^
oooon
SI 35
O0OSI8
0OOS34
nil
■!oO«B
i;it
!
M
SI BO
ioOOSSB
25 0
OOOSM
28 S
000786
310
.OOOTtK
nw
to
GRAPHIC ILLUMINATING CHART. 587
Clrmphic MllwMlmiUiBc CUmrt,
A. E. Pamcb, Trmns. I. E. B., Oct., 1907.
TIm oqnation upon which the chart u baaed is the well-known one.
Where / ■■ niumination In foot-oandles nonnal to the plane to be iUuml-
nated.
C — Candle-power readin|e from a photometric curve.
« <- Ang^ made by reading C witn nonnal to plane illuminated.
a ta MiniTniim distanoe flouroe of illumination to thia plane.
Sohinc this equation by locarithme oonaiBte, as is well known, oi findinc
kg cf C, loff of ooeVi, addini^ same together and subtracting log oi H\
the mkainder giving the loganthm of the result desired, this being exactly
the gn^ic method followed in working the chart.
In Fig. 1, if the distance A-B be laid off representing log C, and A-C a
distsnee representing log oos^, completing the rectangle will nve point D.
It is desired to adcT the length of A-C to the length A-B. however, and
lortonatdy we may do this graphically if from D we draw a line D-B at an
angle of 45 degrees till it cuts the line A-B produced. A-E now represents
kg C + log. cos%. We now wish to subtract from A-B a distance equal
to log ^.
ol
Ii«C + log coe^ — k»g ifi, it now the diagonal O-F l>e properly labeled,
su values of E-F falling on this line will have the same foot-candle readings,
end for evety other foot-candle reading there will be a diagonal parallel to
F-O.
While a diart constructed exactly as per the foregoing description may
be eonveniently used, the form here presented is somewhat different in
snaogement, for by a proper manipulation of axes, one set of diagonals may
be made to do duty for both D-B and F-O functions, and considerable
iavisg in space and oomi>lexity results.
A few samples will elucidate the working ol the chart.
^8sy that from a photometric curve we get 50 candle-power in a vertical
direeiion,and 100 candle-power at an angle of 46 degrees. It is desired to
find the Olumination on a plane at six feet below the source of li^t.
Taking first the 50 candle-power reading. As « in this case is 0, we find
50 on the top candl»>power scale, and follow the diagonal lines to the right
hand margin, giving the point 5. We now follow horisontally toward the
kf t to the vertical uiroum the point 6 found on the lower inclined margin.
FoUoving a diagonal afoun to the right hand margin we find for the value
xequired 1.40 foot-candles.
Again from 100 candle-power on the top scale we foUow vertically to the
horiaoDtal line through 45 degrees found on left hand margin, from this
intefsection foUow diagonal to rii^t lumd margin to 3.5.
Proceed toward the left horisontally to vertical through 6 as before, and
sgsin along a diagonal from this intersection to the right hand margin, giv-
ing 1 foot-candle as the desired result.
As an example of the reversibility of the diart, the following problem will
be solved. Let it be required to construct a photometric curve that will
prodace a uniform illuminadon of 1.5 foot-canoles upon a plane seven feet
bdow the Hgfat source. Find the intersection of the diagonal from 1.5 on
rii^t hand margin with vertical through 7 on Iowa* scale.
follow horisontally to the right to right hand margin, continue from this
point along a diagonal towara the top, and where this diagonal cuts the
eevenU degree lines, will be found the candle-power readings required at
these angles. As 205 candle-power at 45 degrees, 165 candle-power at 40
degrees, 132 candle-power at 35 degrees, 110 candle-power at 30 degrees,
06 caadle-power at 26 degrees, etc. etc., to 72 candle-power at sero degrees.
r
S88 ILLUMINATING ENOINEERINO.
GRAPHIC ILLUMINATING CHART.
589
Sible m. mM|«ir«A nimBUmatloBi for VAriom Cli
•f 0«rvlc«.
Fro/m a pamphlet by the National Electric Lamp AuoeiaHon,
Oam of Service. Ligbt
Intensity in
G«nenu illumioation of: Foot-OandlM.
Auditoriums lto3
Theaters Xto3
Cihaiehes 3 to 4
Blading lto3
Geunl illiiminAtion of raoidenoes lto2
Desk iQuminAtion 2to5
Postal service 2to5
Bookkeeping 3 to 5
Stores, general iUumination 2to5
Storas, clothing 4to7
Drafting 5 to 10
Engraving 6 to 10
rmkUm IV. ftkowiisir AAvter l»J tlhe Vre« of Hick S«cl«a<7
Front a pamphlet by the National Bleclrie Lamp Aaeoeiation.
I
2
3
4
5
6
7
8
10
11
Gkndl^power
Watts per candle, nominal . . .
Watts per candle, actual . . .
Total watts
Hours total life
Cost of lamp
Cost of renewals per year of 1000
hours
Goat of power per srear of 1000
hours at 10 c. per k.w. hour . . .
Cost of power and lamp renewals
per year of 1000 houiB . . . .
Saving over 3.5 W. P. C. lamp .
Saving over 3-0 W. P. C. lamp .
Carbon.
Carbon.
Gem.
20.
20.
20.
3.5
3.0
2.5
3.48
3.04
2.5
09.6
60.8
50.0
1040.
520.
560.0
$0.16
SO. 16
f0.20
0.154
0.308
0.36
6.96
6.08
5.00
7.11
6.30
5.36
• • •
0.72
1.75
• • a
> • a
1.03
Tanta-
lum.
20.
2.1
2.1
42.0
600.
SO. 54
0.00
4.20
5.10
2.01
1.20
Line 5 eves our best knowledge of the life of our lamps with good volt-
age regulation. A slight difference in standards, a variable rw&tion or a
poor regolation wiU cause lamps to average better or poorer than these
nguiea. Lme 6 ahowe the cost of lamp in 10,000 quantity.
ILLUMINATING ENQINEBRINO.
DATA ON ILLUMINATING VALUES.
S
17 v>^
-^ ^^*-
-->^^
Fro. 8.
592 ILLUMINATIffO ENGINEERINQ.
Kxperiaif»ntal JDatA on IlliuilaatiBg' V»la4
From paper by Sharp A MiUar before Ediaon Aasociation,
This auditorium is equipped with a eove-lii^ting installation and with
arrangement of ceiling lamps and side brackets. The Ediaon Gomi
undertook the work of arranging such temporArv installations as „
required for the purpose of the test. These instaUations were selected
the suggestion of the advisory committee in such a way as, first, to ~
out the relative illumination raiciencies obtainable with similar illumi]
variously arranged and variously equipped with reflectors, ete^ seoood,
S've a basis for reliable comparisons of the illuminating ctmci«icaas
luminants of different tvp^.
The fact should be emphasized, however, that the results here given
in all strictness only to the room in question, and that in using thes
in connection with other installations, proper consideration should be ^wi^
to this fact.
The sixteen candle-power carbon incandescent lamps which were used it
the installations requiring such lamps, were new lamps taken from a pae*
which had been purchased recently subject to the inspections of tM ]
trical Testing Laboratories, and which could therefore be considered _
well-rated lamps. These hunps were burned about fif tv hours before Cte i
first test was undertaken. The frosted lamps were sdected in a siw^tt
manner. The actual candle-power and watts of these lamps were deto^
mined by selecting a donsiderable number of representative ones and piioto-
metering them in the laboratory, at the actual voltages used in the tests.
The deterioration of these test lamps in successive tests was also deter-
mined in this way.
It is desirable, also, to know what ratio of the total light which is emitted
by the lamiM in a room may be expected to fall on a plane of reference^
i.e., the horizontal plane on which measurements of the intensity of d*
illumination are commonly made. This ratio of the light generated to the
light utilised on the plane of reference gives a value for the net efficient
of the installation. However, in order to arrive at an expression for ibm
efficiency, it is necessary to employ some unit in which the total li^t fron
the lamps and the total li^ht falling on the plane of r^erence can be cacpresswL
For this purpose the notion of the flux of light is used, and the unit in whidi
luminous flux is measured is introduced. This unit is the " lumoi, *' which
is defined as the flux of light emitted by a source of one candle-power in a
unit solid angle. The total luminous flux from a source of ligl^t is equal to
s its mean spherical candle-power. We can measure ia
4V, or 12.57 times
lumens not only the output of the lamps, but also the flux of light throu^
the plane of reference, and the ratio of the lumens through the pbme of
reference to the lumens yielded by the lamps gives the net efficiency of the
installation. In a similar wav the efficiencjr of the lamps may be measured
by their lumens per watt; ana the gross efficiency of the illumination instal-
lation can be measured by the lumens on the plane of reference per watt
expended in the lamp. The lumens on the pUne of reference are deter-
mined by multiplving the intensity of illumination on this plane, as ex-
pressed in candle-feet, by the area of the plane in square feet, i.e., ^e flux
through a plane is equal to the intensity of the illumination on the plane
multiplied by the area of the plane, or the illumination on the plane is equal
to the density flux of the light falling on that plane.
In measuring the illumination, forty-five stations were sheeted, equally
spaced over the floor of the auditorium. The values of illumination were
then plotted on a map of the floor area, and then all points having the same
illumination were connected by lines. This gives a set of lines which w«
have called equilucial lines, by analogy with equipotential lines of an eke-
trostatio or a magnetic field.
If the lines are plotted representing in all cases the same percentafe
variation of illumination, the closeness of the lines to each other represents
the illumination gradient, or the rate at which the illumination is cnanginK
from place to place on the plane of reference, and consequently the lack v
uniformity in the illumination. Diagrams of this character have been
prepared for the various tests.
A number of such diagrams are given on pages 590 and 691 . These, io
I>ATA ON ILLUMINATING VALUES. 593
. show the amnfament of the lumps and a oondenasd desoription
I of the ty^ of iBstallation is given. These diagrams show lines of umfonn
[fllomimation for various types of installation. The equilucial lines show
diffeieneeB in intensity of ten per cent. Diagram 1 shows the effect of the
rfloye lighting alone; 2, ceiling lamps and brackets frosted; 3, concentrating
— '-mmtio reflections, high level; 4. mirror reflectors, high level; 5, distribut-
^ reflectore, low plane; 6, gem lamps; 7, tungsten lamps; 8, are lamps,
ith dilFuser shades.
In a general way the tests made were intended to show, first, the compar-
(fno between the various pennanent installations in the auditorium; second,
■llie increaae in illumination efficiency resulting from equipping the ceiling
|iuDp8 with varioiis reflectors, and the effect of using frosted instead of clear
bulb lamps: third, the effect of lowering the same eauipment to a point
nearer the floor. Furthermore| gem lamps, tungsten lamps, Nemst lampe
and arc lamps were installed with the idea of obtaining comparative data
«n their illuminating values as used in a room of the dimensions and char-
acteristics of this auditorium. These varying results are summarijEed in
the aeeompanying table.
By a comparison of the lumens which become effective on the plane of
leferenoe with the lumens which are ^nerated by the lampA, we get a value
for the net efficiency of the installation. The value of this efficiency indi-
cates the degree of skill with wtdch the installation has been planned and
sairied oat. It is totally unaffected by the efficiency of the lampe employed
and refers only to the illumination installation as such, irrespective of the
ffluminants used. It is, however, largely affected by the character of the
nwm iHiich is illuminated, as is also the gross efficiency of the installation.
Bill.
Many cocperiments have been made to find the absolute loss of intensity
doe to reflection. This absolute value of what is called the coefficient of
reflection, that is to say, the ratio of the intensity of the reflected to that
at the incident lii^t, varies very widely according to the condition of the
reflerting surface. It also — in case the surfaces are not without selective
reflection in rerpect to color — varies notably with the color of the inci-
dent light.
The following tablejorivesa collection of approximate results derived
from various sources. The figures show clearly enough the uncertain char-
acter of the data.
Material.
Ck>efficient
of Reflection.
GBgUy polished silver . .
IGrrorB silvered on surface
Highly polished brass . .
Highly polished copper .
ffighly polished steel . .
Bpeoolum metal ....
Fblisbedffold
Bamished ooppw ....
.92
.70 to
.85
.70 '•
.75
.60 "
.70
.60
.60 "
.80
.60 "
.55
.40 "
.50
Smooth papera and paint give a very considerable amount of surface
reflection of white light, in spite of the pigments with which they may be
colored. The diffusion from them is very regular, except for this surface
sheen, and may be exceedingly strong. When light from the radiant point
falls <» such a surface it produces a very wide scattering of the rayn, and
an object indirectly illuminated therefore receives in the aggregate a very
large amount of light. A great many experiments have l>een tried to
determine the amount of thii* diffuse reflection which becomes available
for the illumination of a single object. The general method has been to
compare the lig^ht received directly from the ilhiminant with that received
from the same illuminant by a reflection from a diffusing surface.
594
ILLUMINATING ENGINEERINQ.
Val»le V.
C«
mp»n
s«lT« Val«M •€ lUuMlMsUi^a «|g
Iiutallation.
Equipment.
.
S.
6
•
121
2
10^
•
o
4*
t
H
1
1
1
•
1
Core and
Brackets.
•
5
1
CoTe
Clear
Permanent
Brackets
42
8^
2
Clear
Clear
Clear
InatalUtion,
A
16 o.p.
Lamps Oval
Border
IM
14-10
3
Clear
Clear
Clear
Clear
Anohored
Center
98
15-6
4
6
"6
Frosted
Frosted
Frosted
Frosted
Frosted
Clear
Frosted
"~~
HolophAM
16 e.p.
7
ConeeD*
Lamps
Center
R2
14^
All
All
No
tratii^
s
Suspended
from
Alternate
Lamps
ILamps
Side
HoIophaM
Border
48
14-1
8
Clear
Clear
Lamps
IMffnsiBf
Ifirrorea
Sockets
9
10
CoBeen-
Holophaat
11
Conoen-
Same at
Center
62
12-6
All
All
No
tratiai
C
Different
12
Lamps
Lamps .
Side
HolophsM
Height
Border
48
11-10
13
Clear
Clear
Lamps
DtfTodw
Mirrored
Gonoen-
iratiM
Mirrored
Pendent
Same
Center
38
14-8
14
Clear
Clear
Clear
Goneen-
n
Border
48
14-1
tratiw
Lamps
Brackets
12
84)
15
Clear
Clear
Clear
Mirrored!
TUtedCoH
oentratim
Gem
Oem
HoloDhane
Bowl
No. 16, Qem
16
Frosted
Frosted
Border
Tip
Tip
Center
HolophsM
Coneen-
tratlni
HoIophaM
JB
Center
12
13-6
17
Tungsten
Tungsten
No. 17,
Border
12
13^
Clear
Clear
Bowl
Tungsten
Nos. 18 & 19,
Center
12
13-
18
Opal
Opal
Nernst
Border
12
13-
19
Opal
38"
Opal
HolopbaM
DiiTiuinff
^^"
Con-
Dtffuser
Outer
eentrio
Alabaster
6 Ampere
Bobesche
JF
Enclosed
D.C. Aro
9
12^
20
Alabaster
Globe
Inner CloM
Outer
' 1
'21'
Clear
Inner
DATA ON ILLUMINATING VALUES.
595
teUaicy •€
' Ws»
riM
m M«tfeMida •
f iiifiiMBr-
Photometrie Data.
Illumination Values
Foot Candles.
Lam|i.
Effioienoy
Values
Illumination.
^
16.S8
I'
]3w42
1^
3.06
8.73
g Total Watts.
•
M
2.27
1.11
•
1
1.72
•
>
%
29.7
620.
1.48
Lumens
per Watt.
Oroee Lumens
lEffeetive
per Watt.
Net Lumens
Effective
per Lumen
Qenerated.
8.88
0.8
%
23.7
1
14^
122
3.26
3.96
11000
7.10
3.92
6.18
26.7
6.62
8.16
1.64
48.8
1
140)5
llJiO
8.38
4.05
17300
8.41
6.60
1J6&
21.0
6.72
3.06
1.266
41.8
M
13.88:11.41
3.48
4.36
11930
6.63
3.70
6.65
25.1
6XR
2.89
1.365
47JI
■ • «
« « •
* • •
3.12
• « •
3.84
17760
4810
8.00
8.80
6.57
1.96
7.23
8.30
16.85
28.6
6.42
8.08
1.18
89.0
15.6
12.78
8.28
1.91
68.2
f
15J8
12.84
3.22
3.80
4030
5.47
2.08
4.07
36.8
8.23
2.36
72.7
bd
1&.17
12.5
3.28
8.95
4940
5.16
2.08
4.02
38.3
3.19
2.31
72.4
M
15.43
16.11
12.71
13.28
3.17
3.06
8.86
3.72
4900
4940
7.68
4.15
1.60
2.38
4iK2
3JS0
62.9
25.8
8.26
2.86
87.7
oo
3.38
2.02
58.8
n
14.72
12.13
8.30
4.0
4885
6.83
1.86
3.94
50i)
3.13
2.30
73.6
DO
I.V4
12.80
3.22
3.9
4951
6.92
1.91
4.28
46.9
3.22
2.46
76.4
BO
I5.t3
12.63
8.19
3.87
4802
8.20
1.12
4.46
72.4
8.25
2.60
79.6
18
14.9
13.28
8.29
3.99
4798
7.07
.83
■ ■ •
66.4
4.70
3.76
2.79
88.3
IB
15.26
12JS8
32J»
87.8
3.19
2.07
2.43
3.87
3.14
2.93
4775
4328
6.82
4.61
.64
2.08
« • •
3.33
76.9
37.8
3.92
...
3.26
2.33
IIJH
K
ao.i
105.8
4.21
2.0
52.2
«
79.3
63.4
1.19
1.49
1694
4.75
1.88
3.29
30.2
...
8.46
6.52
65.2
<
• • «
37 J)
• ■ •
3.15
2802
8.0R
1.14
2.09
46.4
• « .
8.98
2.12
53.2
f
38.9
• • ■
8.16
2798
3i»
.95
2.21
68.0
■ . •
3.98
2.28
57.3
»
« « «
22.9
• • •
2.7
5590
7.88
2.ar
4.31
67.6
• • •
4.64
2.22
48.9
i
• * ■
22J»
• • •
2.7
6630
6.46
1.73
4.01
58.6
- . •
4.64
2.06
46.3
596
ILLUMINATING ENGINEERING.
The followtng table gives an aggregation of the molts obtaaned bj i
eral experimenters, mostly from colored papers:
Bfaterial.
OoeffieicDt of j
Diffiue
White blotting paper
White cartridge paper . . . .
Ordnary foolscap
Chrome yellow piH>er
Orange paper
Plane deal (clean)
Yellow wall paper
Yellow painted wall (dean) . .
Light pink pa|>er
Ydlow caroDoaKl
Light blue cardboard
Brown cardboard
Plane deal (dirty)
Yellow sainted wall (dirty) . .
Emerald green paper
Dark brown paper
Vermilion paper
Blue green paper
Ck>balt blue
Black
Deep chocolate pi4>er . . . .
French ultra-marine blue paper
Black cloth
Black velvet
BSLIi.
To Illuminate a room 20 ft. square and 10 ft. high on the haals of a oial*
mimi of 1 candle-foot, will require from 80 to 144 effective candle-poww.
according to the arrangement of the lights, if the finish is llffht, and half
as much again, at least, if the finish is dark. The floor space betng €1
sq. ft. it appears that the illumination is on the basis of about 3 to 6 sq. ftp
per effective candle-power. The former fisure will give good illnminatloa
under all ordinary conditions; the latter demands a combination of ligfcl
finish and very skfllfullv arranged lights.
For very brilliant effects, no more than 2 sq. ft. per candle shonld be
allowed, while if eoonomv is an object, 1 c.p. to 4 sq. ft. will famish a
very good groundwork of illumination, to be strenguaened locally by *
drop-light or reading lamp. The intensity thus deduced may be comptind
to advantage with the results obtained by various investlgaJkors. radoeiaf
them all to such terms as will apply to the assumed room whfdh is ante
discussion.
Just deduced
Uppenbom
Piazzoli . .
Fontaine . .
1 c.p. per 3 sq. ft.
1 c.p. per 3.6 sq. ft.
1 c.p. per 3Ji sq. ft.
1 c.p. per 7.0 sq. ft. (approximation}.
In very high rooms the illumination Just indicated must be matedsHf ;
increased, owing to the usual necessity for placing the lamps rather hiidMr !
than in the case Just given, and on account of uie lessened aid rececral
from diffuse reflection. The amount of this increase is rather onoarttbt.
but in very high rooms it would be wise to allow certainly 1 c.p. for emy ^
2 sq. ft., and sometimes, as in ball-rooms and other special cases requtrinf
the most brilliant lighting, as much as 1 c.p. per square foot.
Perhaps the most important rule for domestic lighting is never to nie,
indoors, an incandescent or other brilliant light, wuhaded. Ground or
frosted bulbs are particularly good when incandesoents are used, and opal
INTERIOR ILLTTMINATION.
597
!«, or bolophana globes, wbioh also reduce the intrinsio brilliancy, are
' ible with almost any kind of radiant. Ornamental shades of tinted
or of fabrics are exceedingly useful now and then, when arranged to
oixe with their surroundings.
tsble below is intended as a hint about the requirements for domes-
lighting, and while it is laid out for a fairlv larse house, containing
„ ttty rooms and three baths, its details will fnmisn su^estions applf
hUe to many cases. An 8-c.p. lamp of the reflector variety shoula be
lieed in the ceiling of eTery larse closet, and controlled br a switch from
m room or by an automatio switoh, turning it on when the door is fully
Room.
Ksry* i
MeeptionToom
iuiic room
_,njom .
piJardioom .
nvth ....
Mrooms (6) .
Dtaring rooms (2)
HTTHits' zooma (3)
Smvooms (3) . .
?taitry
BaBB
Teflsr
(4) . . . .
Total ....
8 c.p.
8
12
4
12
14
10
4
64
10 c.p.
14
4
3
3
• •
3
• •
3
30
32 c.p.
1
2
» •
4
1
8
Sq. Ft.
per cp.
4.7
3.1
7.0
3.0
2.7
2.3
• •
7.0
4.7
0.4
5.0
Remarks.
8-c.p. reflector lamps
Eight reflector lamps
32 cp. with reflectors
Reflector lamps
WmUmmt
■sp VerailMals P«r Aqvar* Foot
IWr Hirh Glass Are IJ^hMaff.
(By W. D'A. Rtan.)
Building.
Range.
Average
Condi-
tions.
jsehine shops; high roofs, electrically driven
machinery, no belts
.5 to 1
.75 to 1.25
.5 to 1
.75 to 1.26
1 to 1.5
.9to 1.3
l.lto 1.5
1.25 to 1.75
1.5 to 2
•
.75
aehine shops; low roofs, belts, other obstruc-
tions
1
ardware and shoe stores
epsrtment stores; light material, bric4i-brac,
etc.
.75
1
Epsrtment stores; colored material ....
in fighting; plain white goods
in lightmg; ook>red goods, high k)oms . . .
nsral Office; no inosDdescents
rsfting rooms
1.26
1.1
1.3
1.5
1.75
Nora : Energy based on watts at lamp terminals.
ILLUHINATINQ ENQINEEBING.
P
|5g-s ssSss'i^sk ;||
4="°li«»^ ;|s
:*s!;;s|3isa|||
S-s =a<j
-1; i;|
SSSeS SnXSSai
i^isll ^1
1
^
GENERAL ILLUMINATION. 599
M aubjaet of iUuminatioD has been divided by Mr. E. L. Elliott, to
n W9 are indited for many suavitioDe, into the followinc sub-divisions:
Dflity or brillianGy. distribntion, diffusion, and qjuality.
Bt«aflHgr •f Snlli«»ojr« — The average bnUianoy of illumination
ired will depend on the use to which the Tight is put. " A dim li^t
wvMild be very satisfactory for a church would be wholly inadequate
k tibrary, and equally .unsmtable for a ballroom."
M illumination ^ven by one candle at a distance of one foot is called
** candle-foot" or "foot-candle," and is taken as a unit of intensity. In
ml, intensity of illumination should nowhere be less than one oandle-
» and the dmoand for lic^ht at the present time quite freauently raises
brinianey to double this amount. As the intensity of light varies
arsehr witn the square of the distance, a 16 candle-power lamp gives a
lie-foot of lii^t at a distance of four feet. A oandle-foot of light is a
i intensity for reading purpoeei.
Hiuning the 16 oandle^wer lamp as the standard, it it generally found
t two 16 candle-power uunpe per lOO square feet of floor space give good
ruination, three very bright, and four brilliant. These general flguree
I be modified by the height of ceiling, color of walls and ceiling, and
or local eonditious. The lighting efrect is reduced, of ooune, hy an
peaaed height of ceiling. A room with dark walls requires nearly three
es ae many lights for the same illumination as a room with walls painted
(te. With the amount of intense lisht available in arc and incandescent
iting, there is danger of exceeding " the limits of effective illumination
I producing a glarmf intensity," which should be avoided as carefully as
little intensl^ of illumination.
bin a given space. A room uniformlv lighted, even though compara-
bly dim, gives an effect of much better Illumination than where there is
•t briUiuiey at some points and comparative darkness at others. The
leer Muts. even though actually light enough, appear dark by contrast,
Ue the lignter parts are dassllng. For this reason naked lignts of any
id are to be avoided, since thev must appear as dawlJTtg points, in
itrast with the general illumination."
lie arrangement of the lamps is dependent verv largely upon existing
iditions. In factories and shops, lamps should Be placed over each ma-
ne or bench so as to give the necessary Ught for each workman. In the
Iting of halls, public buildings, and large rooms, excellent effects are
ained by dividing the ceiling into squares and placing a lamp In the
Iter ot each square. The size of square depends on the height of ceiling
t the Intensi^ of illumination desired. Another excellent method cen-
ts in placing the lamps in a border along the wall near the celling,
'or the illumination of show windows and display effects, care must be
:en to illuminate by reflected light. The lamps should be so placed as to
'ow their rays upon the display without casting any direct tajB on the
wver.
lie relative value of high candle-power lamps in case of an equivalent
Bber of 16 candle-power lamps is worthy of notice. Large lamps can be
Idently used for lighting large areas, but in general, a given area will be
Kh less effecttvely lighted by high candlepower lamps tnan by an equiva-
tt Buaber of 16 candle-power lamps. Ix>r instance, sixteen 64 candle*
rsr lamps distrlbnied over a large area will not give as good general
imimtion as sixty-four 16 candle-power lamps distributed over the same
a. Hi^ candle-power lamps are chiefly useful when a brilliant light is
Mled at one point, or where space is limited and an increase in illuminat-
l«ffeet is desired.
IHihel«fM of Ui*bt. — "Diffiftlon refers to the number of rays that
*■ ssehpoint. The amount ot diffusion is shown by the character of the
idow. I>aylifl^t on a cloudy daymay be considered perfectly diffused :
Coes no uiadows whatever. The light from the electric arc is least
, since it emanates from a very small surface ; the shadows cast
^t hsTe almost perfectly sharp outlines. It is largely due to its hi^
tts of diffusion that daylight, though vastly more intense than any artlfl-
ufflunination, is the easiest of all lights on the eyes. It is a common
I
600 ILLUMINATING ENGINEERING.
and Berious mistake, in case of weak or overstridned eye*, to radnoe tk«
intensity of the light, instead of increasiM the diffwion.
ifcrnltty of JLIeit. — " Aside from dWerence In intensity, liglit w^
duces many different effects npon the optic nerves Md their ceojtOT to tte
brain. These different impressions we ascribe to difference in the qiu
ofth; light. Thus, ' har<f light,' * cold light,; • mellow light.' • mii
light/ et?.. designate various a ualities. QuaRty In light Is exactly xmI
to timbre or quality in sound, which is likewise Independent of uit«ntfeb
The most obvious differences in quality are plainly those called <»lj>f • ^HJ
color U by no means the element of quality. The proportion of inriaom
rays and the state of diffusion, are highly Important factors, but on aea
of not being directly visible, they have been generally overlooked, and
but imperfectly understood."
XlM Correct IJso of XJgrM.
BCow to AtoMI H»nMftel Bfiocts ob tlio Sjo«.--An obJeetta I
frequently urged against the incandescent lamp is that it is harmful to A* 1
era and ruins thesight. This is true only m so far as the lamp may bo Im-
orooerly used. Any form of light as frequently moused would produce tta .
same harmful results. Few people think of attempting to read by an u^
shaded oil lamp, and yet many will sit in the glare of a clear glass xncaif
descent Ump. Incandescent lamps are more generally oompla^ed oi,
because, unlike oil or gas, they can be used in any position. Bookke<»ea
and clerks are often seen with an incandescent lamp at theend of adm
hanging directly in front of their eyes -an impossible position of tlie la^
from gas or oil. .
The first hygienic consideration in artificial lighUxig is to avoid the use off
a single brigut light in a poorly illuminated room. In working under sutt
a light the eye is adapted to the surrounding darkness, and yet there is om
spot in the middle of the eye that is kept constantly fixed on the very brl«
light. The briUianoy of the single light acting on the eye adjusted to dai«-
ness, works harm. There should be a general illumination of the room ia
addition to any necessary local light. If sufficient general illumumtlon w
provided, the eye is adjusted to the light, and the local light can be safflly
used. The ideal arrangement provides general illumination so strong thst
a pencil placed on the page of a book oasts two shadows of nearW equw
intensity ~ one coming from the general light and the other from the loesJ
light.
Oare should also be taken to prevent direct rays from striking the eye.
The light that reaches the eye by day Is always refiected. In readii^ «
writing, to avoid shadows, the light should come over the left Bhonld«r.
Only the reflected rays can then reach the eye.
Another point to be avoided is the careless, general use of elear glssi,
unshaded lamps. Frosted bulbs should be used in place of clear gtut
where soft light for reading Is required. The Intensity of light refiected
from a small source is increased, and Intense light injures the eye. With s
dear glass globe the whole volume of light proceeds directly from the smsfl
surface of the Ump filament. With a frosted bulb the light is radiated
from the whole surface of the bulb, and while the total illuminating effect
Is practically undiminished, the light is softened by diffusion, to the grest
eomfort and relief of the eyes. , .. «
Finally, the use of old, dim, and blackened lamps, giving but a smsli
fraction of their proper light, is very often a source of trouble in not suppiT;
ing a sufficient quantity of light. Users of lamps are not otfen aware of
the loss in candle-power a lamp undergoes, and so it happens that lampt
are retained in use long after their efficient ]ightr«riving power hae vanished.
Proper attention to lamp renewals on the part ox Central Stations is nec«t-
sary to correct this evil.
The correct use of light requires :
That there should be general illumination in addition to the light nearst
hand. .^ ,
That only reflected light should reach the eye. The light should be lO
placed as to throw the direct ravs on the book or work, and not in the eye.
That the light should be placed so that shadows will not fall on the work
in hand.
That shades and frosted bulbs should be used to soften the light.
That lamps be frequently renewed to keep the light up to full candle-
CONCEALED LIGHTING SYSTEMS.
601
1
»f MAgm br
It M^ttMl
(bast form of lidbiting intorlors is to have single lamps uniformly dis-
^ over the eeuinis; unless the room has been especially designed
in view, it is sometimes difficult to accomplish.
method giving most excellent results, but requiring more candle-
the arrangement of lamps around the sides of the room close to
If the walls and ceiling are of a light color, this method ia
iaetorr, and easier to wire.
ehandeners, or more correctly in this case, electroliers, are used,
; to have but one main or large one in the room, balancing the Ught
brackets.
ItnA suspended lights should be above the line of vision as far as
It,
eeoDomical distribution, as far as candle-power necessary, is the
where li^ts are evenly distributed over the ceiling. To
luminosity by using clustere of lamps more widely £strib-
of single ones, imll require much more candle-power.
smdifr'Power lamp is the universal standard in the United States
g lamps or illumination, and following are given some ratings
niminatioD of different classes of buildings is figured.
illumination, 1 lamp, 8 feet from floor for 100 square feet, as in
walks, etc.
.-rooms, ferry-houses, etc., 1 lamp for 75 square feet.
oE&oea, etc., 1 lamp for 00 square feet.
.. the above must be varied to suit the circumstances, such as
or other surroundings requiring more light, as the walls reflect
't furnished; and in rooms with dead white walls the reflection
90 per cent, and less lamps would be required than in interiors
le reflecting sorfaees.
iD^enioas and satisfactory method of illuminating his^ arched
id mteriors, developed first by Mr. I. R. Prentiss of the Brush
'^ is to idaoe a number of lamps around the lower edge of the arch
vith reflectors under them, and so located behind the cornice as
is to tJhe eve from the floor.
at arch will reflect a large i)art of the light so placed, giving a
eren iOomination to the whole interior, without shadows, and very
the eye.
m the arch must be oi good color for reflecting the light, or much
be wasted.
of inefficiency of systems in which the lighting is by con-
of light, or different lighting systems, have been dassined by
four neads as follows:
absorbed by oeilings and walls,
due to unneceesary intensity at unimportant points.
iCiveoess of sharply inclined mya.
inteoaity necessary with diffused lighting.
- his expoimental data illustrating these elements quantitatively
I in the f blowing tables.
r. Tnuis. Illuminating Engineering Society. Oct., 1907.
602
ILLUMINATING ENGINEERING.
MlLULB.
Total flux of lif^t, lumens ....
Flux on workins plane, lumens . .
Efficiency of li^bt utilisation . . .
Efficiency of illuminanta (lumens
per watt)
A Diffused
Relative en. of systems; -^. — r
Sacrificed to secure diffusion . . .
Temporary
Installation at
Electrical Test-
ing Laboratories.
System.
Direct.
424
180
42.3%
2.92
Diffused.
4824
579
12.0%
2.01
28 per cent.
72 per cent.
Hariem Officvi
New York
Company.
System.
IDireot.
13938
6642
47.7%
3.34
ZM
32 per eent.
68 per cent.
Table Vm
MiLLAS.
r«v
Angle of Paper
Foot-Candles.
Observer.
with
Horison tal .
Diff. in Par
Direct.
Diffused.
Cent ai
Direct.
H. E. Allen ....
46*
2.5
4.7
184
Night watchman .
420
3.7
4.8
130
Dynamo tender . .
SB'*
1.85
2.7
144
H. E. .\llen
47'»
3.0
5.3
180
W. S. Howell .
470
2.95
6.3
217
C. H. Sharp .
44'*
3.6
5.0
140
Z. N. Corras
49"
2.3
8.1
135
P. S. Millar .
46*
2.75
5.0
181
F. M. Farmer
49*
2.1
5.0
237
E. Fitzgerald .
49*
2.9
2.6
100
2.7
4.45
165%
Note. — The last value obtained, in which the 6XT>erimenter reqnifvl
the same intensity of illumination* with the diffused lifting system that vH ^
desired for the direct lighting system, differs from all the other valos-
Subsequently it was learned that this observer was influenced by the bridit'
ness of the v^lls to select the stated intensity upon the paper, feent
that greater brightness upon the walls would be annoying and unpleawnt
UGHTING SCHEDULES. 603
t*» oondodoDfl are u follows:
) eonditions of the instaUatione were euoh that the increase in inten-
uiredfor reading with diflfused lighting was probably larger than may
jdered a rapreBentative value. The factor is a function chiefly at
^tacBB of toe walls and of the extent to which the walls and other
' illuminated objects come within the angle of vision,
as found that if a placard was viewed at a distance of ei^t or ten
rty times as much of^t was required to enable an observer to read
1 with the difFuBied lighting as with the direct lighting arrangement,
at iaise ooitions of the walls were within the angle of vision, and
I a powenul influence upon the eyes of the observer with both light-
ams. With the direct lif^ting system the walls were relatively
lueneing the pupilary action of the eye so that a low intensity upon
id appeared satisfactorv. With the diffused lighting system tney
liaatiy illuminated and so affected the eye that a very intense
ion was required upon the placard.
the foregoing, the writer nas drawn the following conclusions:
d hating systems of the class considered, where the illumination
ing plane ia one of the prime objects, a large proportion of the light
at which is not lost becomes less effective: bnlliant illumination
xi where it is useless and even undesirable; and conditions are
i wiudi create a demand for an unduly high intensity of illumi-
objects viewed,
effects are present in varying degree in all systems in which con-
large proportion of the light is lost. Among such are cove light-
5, and all systems in whi "
iffusing surfaces used y
reeting adjuncts. Lighting with large sources is more liable to
ig with slnrlight effects, tube lighting, and all systems in which
icy of the ught source is reduced by diffusing surfaces used with-
■M than lighting with small sources.
rts indicate the need for devoting as much care to securing suit-
um intensities, as is generally expended in striving for maximum
certain classes of fighting where more light is asked for, the
ts may be served by reducing the intensity of Ulumination on
t objects which are unnecessarily well illuminated. By taking
af opportunities to minimise intensities at unimportant places
gained, and, in the opinion of many, good lij^ting as well."
UiC^HTXirCl 0Cmi>lTIJB9.
■«nil Iftale for CoaatractloB of Acliod«loe«
— Start lamps one half hour after sunset
nigfat of new moon; start lamps one hour before moonset.
1 lamps one hour before sunrise, or one hour after moon-rise.
ke niffbt before, the ni^dht of, and the night after full moon.
Euner months there wul be found nights near that of full moon
tike rule, the time of lighting would be very short. It may not
to light up during such times.
rvice be desireo, but not full every night and all-night service;
started at sunset and run to 12 or 1 o clock on full-time sched-
12 or 1 on the moonlight basis.
rules bv Ai<nc. C. Humphreys, M.E., have been modified by
ws: Light every nigfat from dusk to 12 o'clock; after 12 o'clock
\TBy's rule for moonlight schedule, excepting there will be no
o'clock during the three nights inunediatdy preceding full
:, "M^^ryHtght ftcli^diile. — Start lamps one half hour
nd extinguish them one half hour before sunrise every day
Full aohedule commonly called 4000 hours for the year.
ire rules serve to make schedules for any locality, and such
b be based on tun time for the locality, and not on ttandard
kvenuM schedules are tised in New York City, but for other
usually made up fresh every year.
ill be found New York City time tables, also another set by
at ia » flood avenge for sun time in any locality.
604
ILLUMINATING ENGINEERING.
H
D
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UGHTING TABLE.
605
n\i
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lo lo lo ae lo iO lo le le lo lo le .
lq«nottott«««ttio««iott«ioioioaoiOioioioioioioieioie<D
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^^
H3?S§?8?Sl??5?§S3SS2S!SSJ;S2^53giaSI^^
^^•^lOiOlOiOlOiOiOIOteiOlOttlOtOlOlOlOiOlOtOiOiOIOlOlOlOIOlO
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joeaoaDaoaoaD«o«oaecbtte»<ftO»Oke»akc»AOttoo»AO»o»ttttaA
s
jSS;g?a^;5885^8S?R§§8????9J??5^???S???§§
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01
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9 00 flo 00 QO 00 00 flOooflOdoaooooot<"t»fr"t*t*t»t»t"t"t*t"k*'*fc*fr*t"fc™
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EvadDC bvin
i
1
1
1
1
s
1
■=
1
1
1
i
i
J
I
...
"J!
i
'i
IS
iii
1
lfi(
217
421
S(
1!
82
^
6
13
33
88
■I!
11
3
S3
2
1
5?
r»
Duik to S o'dwtk
Diuk to 9 o'cbck
Duak to 10 o^clock
D^i to 12 o'cl^k
AllDi,ht . . . .
Uoroinc from
4 o'otoak to dkwn
122114:
1
2
11
1
ec
91
94!
96
195
J
43IT
T2I
u
'
^
UGHTING TABLE.
607
^^ P w ^^ ■— * W^ T^ ^^ ^— ■
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i1
3
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s
9
2
i
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«*ss»ss9ss;sssaasias«8s;aa8s
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o
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I
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U3 lo le lO le lo M> le lO lo lo lO ■> o le lo lo lO lo lo lo le le lO le to lo to lo
2S
^MM^
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I
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UQHrmo TABLE.
i si j5552535$3SS3'3'3SSS3l535l3lli!
SSS5S3Sa52Sa33i5§aSSSIS!lll3!53
sn^s^ssssasaaaxas^sas
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LIGHTING TABLES. 611
BHolsr aU-Dlglit uhednla MWlioan
Kaw Tork Cltr Ktiadnle 3W0 lioun
FUladelphlB Khsduls 4388 boun
ProTidBuee Kh«dnto MlSboun
Phlladelphlk mooBllcht KbHlule Simhoiin
rmdaeudnls 8000 boon
mlmg Canmaictel U^to.
n«,if5-ri««Hi
S^,U.
11
liii
ii
11
a|
i
11
ll
3,
5
?!
431
4jn *xo
B.30
TJIO
T.ao
7.4B
Ifi.45
SM %M
3J0
4J)0
4J0
SJO
fl.3D
BW
6,18
13.00
{ CiBjlihi U^kUmf Bak«<>le far »■■«*»», Mmffimmt,
L 4. — Tbe (ludad >rsa r«pt<MDti Uut tlm« daring whlcb llgbt :
nd. Tb« boriionMI lince inoir tbe moDth* of tb« Tear. TbsTBrtlsi
*9v tha boon of tlia dar and Digbt. Tba Inner dotted linsi ahoir tli
!•«( ■■mil and innrtM. Tbe onter Un«a ghov the time of llihbisg n
I
ELECTRIC RAILWAYS.
Rbtisbd by a. H. Abmstbono, C. Rbnbhaw and N. W. Btobmm.
Tbb electric railway motor has made such rapid strides in tractioii ttaat H
has pre-empted the entire urban field, taken most of the traffic from th* '
suburban steam lines and is now appearing as a formidable competitor to
the steam locomotive in heavy haulage. In considering, therefore, the ap|)B>
cation of the electric motor to traction work, it is necessary to determine its
capacity and characteristics for citv service and single car operation, aed
also for electric locomotives hilling heavy trains, either high speed pasaen^vr
or slow speed freight. Small cars weighing 10 to 12 tons may be fitted witk '
two 35 h.p. motors and be geared for a maximtun speed of 25 to 30 m.pJi. j
lArp^ cars of the sini^e tniek variety wei|^hing dose to 15 tooa may ba
equipped with motors of 40 h.p. capacity. Sin^^ truck cars are used (to a
large extent) for city work, although in this class of work the use of douhls
truck cars is rapidly increasing.
Suburban cars weighing 18 to 25 tons and measuring 46 ft. oTerall
be equipped with four 60 h.p. motors and be geared for a masdmuni i
of 40 m.p.h. Such cars usually make stops approximately every mile,
a schedule speed of about 20 m.p.h. outside of the city lixmts. I^r^er typM
of suburban cars 50 ft. overalL seating 52 passengers, weigh 28 to 30 foaa
and are eqmpped with four 75 h.p. motors geared for maximum speed cf
45 m.p.h. These cars usually make a stop every mile and a half, and m
schedule speed of 25 m.pJi. for the local and 35 m.pJi. for the expnm eais
outside of the city limits. The lar|[;est tsrpe of suburban car, of whi^ thatd
the Aurora, Elgin A Chicago is tsrpical, is equipped with four 125 h.p. motocn;
is geared for maximum speed of 60 m.p.h. ana stops but once in two or thies
miles, making a schedule speed of about 35 m.p.h. These ears represeDt
the highest type of interurban electric railway and their use seems justified
under certain conditions.
Cfmdea. — Grades upon city lines may run as high as 13 percent, and to
surmount these it is necessary to have every axle od the cars equipped with
motors; thus a sin^e-tnick car would reqmre two motors and double-traGk
cars four motors; and even then the oars will be unable to sunnonnt thess
grades with very bad conditions of track. Surface cars operating over dtJr
streets have no option but to use the prevailing grades, hence for city work
where 'heavy grades are liable to be met, the motor capacity per car shodd
be liberal, not so much on account of the danger of overheating the mot<ns.
as to prevent undue sparking when surmounting the heavy grades. The
tendency of the suburban roads is to operate over private right of way, and
grades on these roads do not generally exceed two or three per cent, except
for very short runs where they may reach four or five per cent. Gmae*
exceeding these are infrequent, and on the best high speed suburban roads
two per cent srade is the maximum allowable. The effect of grades upoa
the heating ormotors is largely compensating as the motors cool off nearir
as much in coasting down grades as they overheat when doing extra work
in surmounting the grades.
Cnrrea. — In citv work sharp curves are necessary in rounding strest
comers and curves of 50 ft. radius are sometimes met. These curves are
oftentimes so sharp as to prevent the use of heavy, long double-truck sub-
urban cars. Such curves cannot easily be avoided and dty ears are designed
with short wheel base of trucks, generally not over 6 ft. m order to be able
to round these sharp curves. The maximum speed of city oars is limited
to about 15 m.p.h., so that these sharp curves cannot interfere seriously with
he schedule.
Suburban cars operate over much straighter track and have a maTimnm
speed of 25 to 50 miles per hour. It is seldom that the curves are sbaip
enough to seriously inconvenience the purely suburban class of service.
Roads operating over private right of way endeavor to limit the curves to
five degrees, which can be rounded at a spteed of 35 miles per hour, so that
612
*ar
ELECTRIC RAILWAYS. 613
to BOt seciouBly interfere with the schedule. Very high speed suburban
wiB not p^^nit curves of more than three degrees, as a sharper ourva^
inlerferee with free runnine speed of the cars, which sometimes
caches 60 miles per hour. Sharp curves are more detrimental to the
teoaiMae of hiffh speed than graoes of four or five per cent unless the
- be of ocmaiderabie length.
»■■« «f OpenstlOB. —There are four systons of operation now in
electric raUways, each of which has some distinctive advantages
uiting its use under oertain conditions.
2>. C. ffeneraUon and D. C. diatrHnUion with the poanbU tue of hoosten
(iHhq seorage ftotteriet. — This system is pre-eminentl;sr adapted to the
^eMCBBted travel of the more densely populated sections ol our larger
<«. It is not well adapted to the operation of roads covering large areas
( ii impidly becoming obsolete, owing to the great amount of feeder
Mi ii4|iiired to transmit large amounts oi energy at 000 volts, which is
Hwrd poteotial used. The use of boosters is objectionable for con-
work as they add largely to the fud expense, while a floating storage
at the end of a long feeder is oftentimes more expensive to install
t «i«nte than some of the other systems described later. ^ The direot-
i generatfaig system for lar^^ supply is rapidly becoming obsolete,
in localities where the conditions are very favorable for its retention.
ti^Ui I w<if I'lijii < ufftnt peneration and transmiasion to rotary converter
— This system is being used almost entirely for our suburban
■ad laz«er city systems. Alternating current generation and trens-
offers the advantage of the ability to transmit ffreat power over
tanees at very high potentials, in some cases reaching 00,000 volts,
(the copper expense is relatively small. New York City is fed entirely
y converters which receive their power from alternating current
and alternating current transmission lines at 11,000 and 0,000
The ofibe of .the rotary converter sabstation, which was fint used
m to redaoe the high potential alternating current to low potential
ing eonent, then convert it into 000 volts direct current which feeds
trottey or third rail, as the case may be.
»<iAas0 aUemating current feeding direct into high potential trolley
tmio tkree-'jJuMee motore upon the care is used on some European
eingie-jiha^e aUemating current eommtUating motor has been devel-
I several ffonns sinee 1904, and there are now quite a large number
opemtiiig in this country and abroad, using this type of motor.
)r is said; to be more flexible than the three-phase motor, as it has
B qpeed characteristic very similar to that of the direct current
\mator. Its application in the railway field is therefore much more
''I and it will undoubtedly find considerable use in suburban work
the heavier class of dectric railways.
\mWw%tMamm — The resistance offered by air against the front and
a rapidly moving car forms a very important factor and has been
bsyeet of a large numbtt* of experiments. The most complete are
qr the Berlin-zloesen experiments where speeds of 125 miles per hour
rnached and wind pressures noted. A large number of formulse have
Jbtrodooed by different authorities covering the resistance offered by
'r, tailB, joumaJs, etc., when operating single cars and trains at different
\ The formulse developed bv steam railroad experimenters using
trains of many cars may be discarded as worthless when applied to
e tractam using single car units. In the same way the results obtained
the operation of sin^ cars cannot be applied to trains, as the wind
m of the soooeeding cars is not as great as that of the leading ear.
. train friction reeuits will be treated and commented on later on in
jtliaptcr. Wind friction plays a very important part in determining
*"' eonsumption of eleetnc cars operating at high speeds, and both
_j consumption and eapadty of Uie motive power plant must be
ly determined with a full experimental knowledge of wind friction
_ _ ite. — Gar equipments have increased from motofs of
_ for small singlo-truck cars on city streets to motors dl 550 h.p. each,
the '* Mohawk '^tjrpe of electric locomotive designed for the New York
* Railroad. Electric motors can be designed to meet practically any
of operation, but the standard lists of manufactureiB run from
f
614 ELECTRIC RAILWAYS.
25 h.p. to 200 h.p. in about 25 h.p. steps, in the lai«er sims. and lew differ*
enoe in capacities in the smaller sues. It is better to refer to ihe mamrfse-
turers when a motor Ib to be selected for a civen class of service wbadk
differs materiaUy from a known service upon whioh fuU data is at liaad.
With such a wide ransn in capacity of motors it is neoossary to stiadv the
conditions very carefully in oixler to properly determine the correct sias of
motor to use. Some general curves are given later from whieh irawniaMj
correct approximations can be made, but these should be verified by oo»
sultation with experts in motor design.
IfOOOHSOtlTee. — Electric locomotives have been built for a variety of
purposes from yard shifting to the hauling of passenger trains wei^ag 900
tons at speeds approaching 60 miles per hour. Nearly all these eieetne
locomotives so far have been equipped with direct current series woond
motors operating at 600 volts. A number of locomotives in Europe, how-
ever, have been equipped with three-phase alternating ourrsot motors and
a few with sinfl^e-phase motors. In this country there are now in operatiaii cb
the Spokane a Inland Railway, 1907, six 50-ton locomotives, each equippsd
with four 150 h.p. single-phase motors arranged to optfate on eitner 600
volts direct current, or 6o00 volts sinc^e-phase alternating ounent. The
Westingbouse Electric A Manufacturing Company, who buut these loeomo-
tives, have recently completed thirty-nve 88-ton electric locomotives, each
e(|uipped with, four 250 h.p. single-phase motors arranged to operate ob
cither 600 volts direct current, or 11,000 volts sinjde-phase, alteraatiag
current for the New York, New Haven A Hartford Kailroad, and also six
60-ton locomotives, each equipped with three 240 h.p. motors for operatioB
on 3300 volts alternating current for use by the Grand Trunk Rauroad ia
the Samia Tunnel. The use of electric locomotives is rapidly inereasxng
as the economic operation and other advantages of their operation are
appreciated.
DeelnOtle Poimte ta noton and Car Bqalpnieat.— It is denrw
able that motors should be electrically sound, i.e., that their insulation should
be high, mechanically strong, and waterproof. It is of great advantage in
this connection if the entire frame of the motor can be insulated from the
oar truck and consequently from the ground, thus relieving the insulatioD
of the armature and fields of half the strain. The mechanical diflBeulties
in the way of accomplishing this, however, go a great way towards eouatsr-
balancing the advantage gained.
A high average effidenoy between three quarters and full load should be
obtained if possible, but mechanical points should not be ne^ected to obtain
this.
A motor should run practically sparkless up to } of its rated caimcity. A
low starting current obviously is desirable, and for obtaining this nothing
is better for continuous current operation than a multiple series contnrfling
device, which cuts the starting current in half. This device also enabiei
cars to be run at a slow speed with good efficiency.
Mechanically, the motor should be simple. The fewer the parts, and
especially the wearing parts, the better. It should be well encased in a cover*
ing strong enough not only to keep out water, pebbles, bits of wire, etc-.,
encountered on the traok, but to ^love aside or slide over an obstmetioa
too high to be cleared. At the same time, the case should be hinged so that
by the removal of a few bolts access can be had to the whole interior of the
motor. The brush holders and commutator should be easily aoeonible
throui^ the traps in the car floor at all times. As much of the wei^t of
the motor as possible should be carried by the truck on springs ; if practicable
all GC it. This arrangement saves much of the wear and tear on the trado-
A switch in addition to the controlling stand should always be j[>rovided,
by which the motorman himself can cut off the trolley current, in esse of
accident to the controlling apparatus.
Roads having long, ste^ grades should have their oan provided with s
device for using the motors as a brake in case the wheel brake gives oitt.
There are several methods of accomplishing this, but limited apace prohibits
any description of them.
Last, but by no means least, all wearing parts should be eapable of being
eatUv and cheaply replaced.
WEIGHTS OP RAILS.
615
yfrmmitktMTm or mammm.
Ttfd.
26
30
ft
48
60
a
a
M
58
68}
60
83
63
per
67
70
n
Weight per Mile.
iJong Tons.
640
47;
320
2240
66
1920
'^ffliO
960
^^^240
IMO
'^2240
1600
®^2240
960
88
320
^^2240
2080
•^2240
94^5-
•^2240
960
'"2240
99
%
1760
108
2240
320
2240
640
2240
1920
110
111 280
2240
39.286
47.143
66
62JB7
70.714
74.428
78.671
81.714
86.428
88
91.143
91.928
94.286
97.428
99
99.786
102.143
108.714
104.5
105.286
106.867
110
111.126
Weight per 1000^.
Long Tons.
986/r
"2240
2060
®2240
933.3
lOffliO
11
2026.6
2240
880
635^
**"2a40
14
.1973.3
2240
1066.7
"^"2240
826.6
*®K40
1604^
** 2240
IT
686.7
17.-
2240
1920
17,
2240
920
2240
1013.3
*®2240
imo
^240
18
2013.3
19
2-.M0
773.3
2240
1440
%240
1773^
*^'2240
2106
^^40
Jg3.3
^2240
2000
2^2240
^*2240
7.441
8.929
10.417
11.906
13.383
14.284
14.881
15.477
16.369
16.667
17.262
17.411
17.857
18.462
18.76
I0.BW
19.346
19.643
19.792
19.910
20.238
20.888
21.131
616
ELECTRIC RAILWAYS.
¥rN«BIT« OF ViAMMM^ QmHnMed.
Ponndfl per
Yard.
72
76
77
78
80
82
86
90
91
96
100
Weight per Mile.
Long Tons.
390
1132240
1920
II72JJ40
121
122:
820
125;
2240
1600
129
2240
1920
2240
1280
060
143
164
157;
,320
2240
113.143
117.867
121
122.143
126.714
129.867
133^71
141.^8
143
IM
157.143
Weight per 1000 '.
I^ngTons.
960
^^2240
720.2
^2240
22
2063.3
2240
480
23
1813.3
24
2240
906.6
26
2240
666.6
2240
1760
186.6
27 2240
373^
29^40
1706.7
29 2240
21.4S9
82:917
2S.214
23.810
M.406
26.786
27UI63
29.167
29.76S
For iron or steel weighing 480 lbs. oer cubic foot : Cross-section in aqaan
inches = weight in Ihe. per yard -7- 10.
Gross tons of rails in 1 mile sin^e track ■■ — '^ TH^ .
RADIUS OF CURVBS FOR RIFFEREMT RSARnDl
OF CURVATURE.
t^
!
^s
•
tsS
i
«9
•
!
^3
^3
1
1
11
1
11
1
l|
1
5730
11
621
21
273
31
186
41
139
2
2866
12
477
22
200
32
179
42
13«
3
1910
18
441
23
248
33
174
43
13S
4
1432
14
409
24
238
34
169
44
130
6
1146
15
382
26
229
36
163
46
m
6
966
16
868
26
220
36
' 150
46
IS
7
818
17
337
27
212
37
166
47
12
8
716
18
318
28
206
38
160
48
119
9
636
19
301
29
197
38
147
48
117
10
573
20
286
30
191
40
143
60
m
NoTB No. 1. — A 1° carve has a radius of 5730 feet; 29 curre, fthis; 3^
curre, | this, etc.
OF OUTER BAIL ON CDBVE8.
■ pia cwn aud ■»•■ ra w
lirtD Dlitwioea.
~l «.,>.
IWO Feet.
ls,XSO FmI (1 Mile).
U
5
26.4
1
7M
-For
other diatanaw
Interpolate tbsta
ri*ir or •!:«■■■ mau. on ovrvbs.
Bpoed In Mllea p«r Hour,
ij lfi|2o|2s|3Cl|-3s|40|u|ci0|<
Slevation of Ou(«r Kul
in In
Chi*.
i
,.'
1
1
1
3
n-
2
i
1
i
Si
•■
I'
ID
f
61
• 1
12 1
"
4
^
"i
gjt
11 '
1?
.K=:eJeT-«
■JlBbO
V ^ velootty of car In feet per aeooud j
B ^ radlOH of inrre In fMt ;
E = 1.7B7B ^irben gange of truk ii I'-BI"
618
ELECTRIC RAILWAYS.
size.
No. per Keg of
200 Lbs.
LlM.per Spike.
Spikes per Lfeu
6 X k •
m
633
680
620
393
466
384
360
200
3752
.8077
.3846
.6089
.4292
JS206
.6714
.7692
2.68
3.26
2.8
1.98
2.3S
1^2
1.15
SPJLKBS JPBR 14NNK AITO PKR MUJB SliirO&S
Spacing of Ties.
Per lOOy.
Per Mile. ,
lOtieetoSO'rail.
11 " " " " .
12 •* «« " " .
13 " " ". " .
14 " " " " .
16 " •• •• " .
16 " " " " .
1600
;^
2000
2133}
7049
7744
84tt
mm
9866
10609
11264
•
J-OIHTS PKIK MMI.B
OF •IHOIiB
VRACK.
Per 1000'.
Per Mile.
Joints --SO' rails
Anffle ba.ra
400
533}
800
362
704
Bolts — 4 hole iMtrs
11 6 ** **
11 8 ** **
" 12 " ** !'.!!!'.
140S
2112
2816
4224
TIJBS PKIK 14M>0^ AMD PKIK HKILM^M.
Spacing. *
Per lOOO'.
Per Mile.
10 ties to SO' rail
333}
868}
1760
11 " " »• •
1936
12 11 II 11 (1
40p
2112
13 «« " »« «*
^
2288
14 II II II II
24M
16 " " " ** .......
600
2810
16 " " " ♦«
533}
2816
BOARD FKKT, CUBIC KEKT, AIfl» M^VAIKB VU<
OK BKAIKIIVG SVKFACK PKIK TEK.
Size.
Board Feet.
Cubic Feet.
Bearing SorbM
6" x 6" x T
14.56
1.213
2.91
6" X 6" X T
17.6
1.468
3J(
f/' X V X V
20.41
1.7
4X)8
5" X 8" X 7'
23.33
1.944
4.66
6" X G" X V
21
1.75
SJS
6" X 7^' X r
24.5
2.041
4.06
6" X y' X V
28
2.333
4.66
6" X 9" X V
81 JS
2.625
6.S5
e^xio^'x 7'
36
2.916
6JS
6" X 8" X y
32
2.068
6JS
6" X 9" X 8'
36
3
6
6" XlO" X y
40
8.333
6.66
L
ChuiT, blMk vkIduI, looiul .
Kad uid bU«k oalu . . . .
Ath, bsacli, uid nuple . ■ .
Cfpr«aa uid red ceditr ....
nnuinck
LoDsleat pina
H^lDck
I HllF not ba dsng
g Id ciil«* In tha i
- UMTlkl,
DthBtIt Itdlfflcult tuaUtea
'en an wproilnutB o«t
■t kU anka (or uptialt,
= *8B.
Per lOOO'
Par mlla ioB = ^Kaji
jardi.
uid Labor.
PATBMKNT.
i
1
1
"1
It
s
•
*
f
4NW
JiO
TUB
eat e( single tmok par day.
cai« It la dadred to prwieed D
■ TBACK i-AvntC) womcm.
it tnwk-l>Ten,
a; from lio to
rapidly, Iha abore UDDibar of mao
■bonld l>« tiwMftied propoTtloDstelT, c
theM tiro tIQ bt able to buidle u* i
how widely DCBtteTad, II ■ hone uid bi
Taob for Truck Qau' m» Al
iMliBd, I omall Sit lar, 1 ponsble (on
eiba-: 1 sledKe.l2 Iba.; 2 sic*, 2 mIm.1
Willi bits, 1 track "J:
transit, 1 leveling-rod. 10
lu-iiuM anoveia, lo uuu|
ifflit-«dn, 4 pair nil loi
ther end ohiael-poi
ma, 111 jurveyor'i mi
chalk. 1 uuirt oil-a
oi tula, 1 bro«d-b
BAIKIVAV 1
By W. E. Uwi
Wot siunple, uaiunt it nllwa; to
minatea, with a la; over at «ach a
The time neceaisry to mn from
tarminuB to teriainiu la hslf of at
mliiDt«, le« I of ten miDuCea (the
UyoTsr lime), or 2B minatea. liet
•uh dlvlilan on the ordinate aili
rapreuDt the dlitaaca traveiaed by
K oar !□ one minute, which Id tbs
abOTS oaae Is 8M^ feet per mlDnte.u-
nille» per honr.
I minutM. The
onsl lineOA. Thli 1
the other termlnns will have a lay- I
over of Ave mlniilea ■« repre-
■ented by the hnrlzuntal gbane AB.
Upon the expiration of the time of )a'
ran. Thla detemlnes the loene of the
Eiiaa eath of the renmlnlnE cara. The I
T the line BC. tlnon the arrlial of tli
time the Brat ear la rtmnlng Iti ronnd
tarrala of IS mtnnlea. aa repreeented bi
theee three tinea interaeet the line BC t
meat and paaa at theae points. The dist
their dlKtance from the atarMns terrain
projecting the InteraeoHone on tbe alia
t. Thennmberof (omonta for aglTei
lumber of ean rauilng.
^
BAILWAY TURNOUTS. 621
I time eofuofflad rooBing between tumoiita mnet be the lame
all the turnouts. For insUnce, If it is foand neceM&ry to Irrego-
^te tornoatfl for any reason, then the time eoneumed bv a oar ron-
roen these two tuniouta farthest apart determines the time the
; nm between the remalninff turnonts, even though two or more of
<ati be only a slight fraotionof the distance apart of the two
les.
{me eonsomed ronning between two oonsecntiTe tnmonts is one*
mninff time between cars.
rminiog the distance apart of turnouts without the aid of graph-
is:
To the length of the railway from termlniw to terminus add the
ar would travel ronning at the same rate of speed as running on
16, for the time of lay-over at one terminos. DiTide the abora
16 number of cars desired to be run, the result is the distance
Qonts. Moltlply this latter result by two less than the number
fedoct the result obtained from the length of the line from ter-
ninus, and divide by two. The rorate is the distance from
ins and the first adjacent turnout.
more or less cars on a railway than It is designed for is a quea-
luently met in railway practice.
us that we must have one turnout less than the number of
In Fig. 1 we liave four cars and three turnouts. If we pro-
hree cars we would use two turnouts, by omitting the middle
result is at once apparent : for according to Rule 2, the time
n turnouts is determined by the tim« consumed in running
two turnouts ftkrthest apart. Since the distance is doubled,
aied is doubled. Wherewith four cars, with fifteen minutes
nd sixty minutes for the round trip, with three cars the time
• by Kule 2 is thirty minutes, and the time of round trip is
making at once a yery pronounced loss.
an« ana the one usually pursued by railway managers, is to
aumbor of ears on the same trip time as the raUwaV was
1 our example above, the three cars would be run as if the
lunlng. with the exception that the space which the oar
ig in will be omitted, leayins an interval between two of
ty minutes, giving only the loss occasioned by the omission
h] to pursue, especially so where additional cars will be
1 BB holidays, excursions, and other times of travel reauir-
) regnlsuc number of cars to accommodate the travel. Is to
a mora tomoats. The expense of doubling the number of
ey would be a great convenience, would not be warranted
ay were doing a lArge and growing business, with a fluctu-
irs in service. Two cases should be considered.
.in fixed number of cars are to be operated for the greater
1 the extra cars for odd and infrequent Intervals, locate
t the regnlar business.
3aae of a railway running an irregular number of cars ->
rar running a heavy business at certain times of the day
mSer of cars are subordinate to the greater number,
to run the greater number of cars the most efficiently.
e might state that the grades, the running Uirough
reeta, stoppages occasioned by grade railroad crossings,
tSy all enter In and must be considered while designing.
3F OUTER HAIL OK CURVES.
Blie In Feet Kt GlTsu Diitasoa.
F«.t.
1000 Feet.
K,2«0 Feet <1 Mile).
g
S
other dlitancB
le by direct multl-
.
SlIMd
nMUw
per
Hour
I
l.|l,|»|»|»|-»|«|«|«|«
»
s
1
»
J
■1'
4
a
i«
3,
1
'(I
4
}
I
;
1
1?
1
1
1
(
i
'
1
Tiartten E = 1.78TO g-wlien gauge of ti
BLOCK SIGNALLING. 623
wfar tbe iviteh, otfaenriae it would rastore th« signal set by th*
idly io U)e block.
R— In this type the tit>lley switokes ara loeated on iho double
■ turaouts. These switches are single noting and will only set or
he offiBl II srrufed for. lliis tjrpe requiraB four switehes per
It ins tlM tdvanticB that a oar can oaas under the swit<^ in the
inetioD without restoring the sifniar. It requires that the oars
I the tunottti in one fixed direction.
' lepreseDti a combination of Type A and Type B, and osui be
eet ^Mcial conditions bf road and travel.
IBlreMeate ef a SlgmAl •jst«Hs »r« mm folio we i
oil and dectrieal simplicity of all signal movements and applianoes
automatic, npn-interfering and interlocking;
Inespeble of wnog Indioatione under any of th« foHowing men-
litioDs, and must not permit restoring to normal except under
ditions of operation, otherwise it oould be set or xevened by
flotering the blodc.
rent on signal lines,
oal fines.
lis setting 8i|;nal lines or on the restoring signal lines,
le troiie^ wire between the setting or restoring signal lines.
is set in one direction luid the line then opened, it must be
t( being set from the other direction, i.e., tne si[epMl must be
^ run under a trolley switch when the signal is set agsinst it,
restore the sij^l, i.e., it must be non-interfering.
ploy as few wires as poesible.
Dpoesible to get two safety signals should cars operate the
each end simultaneously. In this ease both sig^tal mov»*
d set, and it is desirable that they ma^^ be automatioally
he oar leaving the block without being required to be manually
tion of an electric railroad signal requires i^t each end of a
cars in both directions the following, with the
aent and a lighting and extinguishing switch.
Ciired are these:
wire from same to signal box^
; switch wire from same to signal box.
rires.
king and an extixiguishing signal line wire running between,
as at each end pi^the block.
;tion between signal movement and rail.
d connection between signal movement and trolley.
ter should be attached to the permanent feed wire and one
nal line wires.
rmbered that the trolley is connected to the ^px>und when-
is set and thus a path of low renistanoe and mductance is
y ligiitnins <lischarge which may take place on the trolley
led upon the signal systems that are in practical operation
oode, and does not apply to systems as used upon elevated
tter are operated by track instruments and give only
ndioatione.
^m. eonsieta simt>ly of a group of larope &t each end of a
to licfat and extinguish tne same. This system operates
r to the automatic system referred to in the first part of
iljies the stoppage of the ear to set the same or to restore
aotioe it has been found that the signal has at times been
peo|3le ^mrho are able to reach the switches which are
*nggsido the track.
les in use are of two types. One consists of a i>arallel
) trolley runs and in so doing oonnects the two sides of
<le 10 permanently connected to the trolley wire and
n&l mo-venie&t. This switch will not difFerentiate in
624 ELECTTBIC RAILWAYS.
direotion and muat theref ora be placed upon tumoats and not
main line.
The other type is a mechanioally operated ewitoh which has a _
lever hanging down and straddling the trolley wire. The trolley
strikes this and moves it in the direction in which the car is going,
pendant arm Is about four inches Ions it remains in contact with the
wheel only about one-fifth of a seoona for a oar si>eed of a mile per houri
proportionally less for hi^er speeds. This requires that all swttcfaas *^
a retarding device to keep the contacts closed longer than would the
wheel. The most common switches to-day use a pallet and wheel
ment as retarding devices.
Kl«ck •igvMU.
The following description of the Block Signal System made by the
Signal Go. of Boston, Itass., is illustrative of what such a simal must i
plish. Fig. 3 shows the wiring for a complete block and rig. 4 the
wiring at each end of the block.
The signal movement consists of iron back plate upon which are
three magnets known respectivdv as the ligjhting magnet, extir
ma^et, and locldng ma^et. The first two mentioned are of
resistance while the third is of 10 ohms resistance. The magnets are of
well Imown semaphore type. The lighting and extinguishing magnets *
notched iron cores in which loosely play one arm of a swit^ing
In the extinguishing magnet there is also an additional magnet core
when down doses a pair oi contacts. The other two contacts are shoi
in Fig. 4 directly above the large magnets and are circular contact di
loosely mounted upon a rod between stops. These rods rest directly n|
the magnet cores and are moved to open or dose the contacts as the i
ment operates. The armature of the lockinf[ magnet is attached dl
to the rod over the exting^uishing magnet and is so adjusted that it is agali
its seat ^en that contact is made and the rod in its lowest poeitioQ. *"
lamps are of 110 volts and one-half ampere and the resistance plate of
ohms is dearly shown.
The operation of the signal is as follows, and can be seen by refereace
Pit3.
when a oar enters a. block it causes current to pass from the tR>ney
through the lii^tinjs magnet and resistance plate to ground at that
Hub causes the switch lever to be thrown over to the left hand con!
thus causing current to be taken from the leaving end of the block, passii
through the red lamp, locking magnet at that end, and then throi^ tl
lij^ting signal fine to the entering end, where it traverses the green lam^
and resistance plate to ground.
To extinguish the signal, current is taken from the trolley at the leaving
end of the block through the extinn^uishinc magnet at that end« thence
through extinguishing line to the entering end and through the extinguishing
magnet at that end to ground throu(^ the resistance plate. It mi^^t appear
at first sight that there would be current throu^ both magnets at the enter-
ing end, and under sudi condition impoesible for the switch lever to be
restored to its normal position. Examination, however| will show that
as soon as current is established in the extinguishing circuit Uie gravity
armatures, so called, at their lower end, are raised, and the one in the leaving
end of the block cuts off the current of the lighting magnet in the entering
box, thereby allowing the extinguishing magnet in that box to operate. B^
taking the permanent feed from the leaving end and also opening that eiraoit
at that end, it will be apparent that grounds on the lig^tin^ line will not
prevent the restoration of the signal. A cross between the signal lines wffl
not restore the signal, but will extinguish the green aigniU. whidi wHI.
however, relight as soon as the cross is removed. Grounds on either ixnei
will not restore the signal when set. Ground ovw 1600 ohms resistance wfll
not affect the op«ation of the signal even if on both signal lines at the same
time. This is equivalent to i ampere leak while the normal current in the
signal circuit is only ) ampere. Ixms of current will not restore the eignsl
^
BLOCK BIQNALUNG.
625
Mi and wfa«n tiw eanwi is ratumed the signal will indicate tiie same
«id tin fa'shtms dranit be open after the signal is set* for instance by a
bflio{[ burned out, and another oar at distant end should enter the
it will be seen by Fig. 3 that the switch lever in that signal move-
it that end irould M tnrown over to the left-hand contact as in the
ovD at the left hand, the result being that the permanent feed is out
lotb endi and no lignal is obtained. LAok of green signal on entering
traed as a danger or eautionarv signal.
ose that a ear should pass under the lighting switch at the red lamp
a bloelL as repreeented by the movement at the right hand side
3, it will be seen that current will be taken throu^ the lighting
at that end and thenoe through the resistance plate to ground. This
Ihi^ti^ Win
LA
^t^tA
OcruMe AcHnglrvltoy Svttchat
L €avj0f£ft^0fB/§ck
J
Fio. 3.
3ve the lever or switch arm over to the left hand contact,
tbe mimnal vrere it not for the looking magnet whose sole
'veat tfikr movement. As soon as the lighting circuit has
lie looking magnet at the red end is energised and its oore
ie»t at tfaat time it is held there. To the oore is attached
>ther end of which is one of the contact discs mentioned
wxhI presBins against the lever arm prevents the lighting
toting it. It will be noted that the locking magnet is
\ lias oo naM>vin^ part to operate before locking, and on
led ma^pnetic circuit is more powerful than the U^ting
nature la retracted at that time, and has a large air gap
tbuB 18 made non-interfering.
ELECTBIC BAILWATB.
In Typa B nsnal ouds by tb« lama oampany. tha virilv is Uw ■
•iBKiI tbmt the mutui«e puM ia plMed in the panuuiint fnd, «Bd
additioiul cnphiu ndnuae roda of 600 ohina an pbwcd io cadi Unl
■wiufa itf. Etiib Itunp ii further pcoWoIed by ft pwar ihnat wbiob da
tbaoirGuit irtwo the lamp bum out. FortbernHra tn w le ft mtniM opft
Uni ■ red, end dim opecftUu a (reeo wmapbot* (Hie Bioal. irlueh
into the ciniuit adjaeent to the red and gntat lankpa.
The UoUajr ewlMhei aia double setiai sod dlBerantialms, op«n
Fra. 4. SiCDftl Set ftt Edterinx End o( Bloek, Oraeo Imdp LWiUr.
toUowa; Tbe firat blow of the tn>ll«)t wheel hiu a pendant hausbic ma ll*
win and brin^ the twitch oontaoti iota weehaninal loeic At the Mdi
time it winda up a pallet <Mapara«Bt. whieh. when it ruui down, kkta iM
loek oil and allowa the eonlatit to open atter a predetermined tunc, Vf
working parte are in balanoa and made aa li^t ae oanaliteat with ■tnnft''
Ufhte when tuieed under in one direction, and natorM 1^ ei^ni
operated in the olherdiTection. A time elenuut ie neoeeanry, aj it nqiuf*
atxnit i aeoond [or the aisnal mechaniam to opemt*. The power laQiui*)
to operate the ■ignal switDh ig 21 pounda pull, while the (eoiion on a (ro&r
wheel to bold it acainst the ironey wit* u over twenty pound*.
BLOCK SIGNALLING.
627
Atotribitod Mffwiil Block ftjattuB.
doped by R. D. Slawbon, Eleotrioal Engineer of Eaeton Ttaosit Go.)
ii is • nuurad qfit«in» and is used by the Easton Transit Goxnpany on
utim, hdlDtt rad fiethleham division, and differs from others in having
{Dsb dutributad along the line between turnouts. There are two seta
ik, one beiiiE used for oufe-bound and one for return oars. The signal
an eoelosed^in alvianiied iron boxes, attached to poles along the
SKgiiai poles are abo painted with two 12 inoh bands of white, and a
r either red or green, ae the case may be. Switohes are looated at
d of the turnouts on poles and the covers are marked "Throw on "
Trolley Wire
iagnun of Oonneetions d Slawson's Distributed Signal Block
Byttem for Singie-Traok Railways.
off/' and each eonduotor Is responsible for xnaintaining his own
iilated iron wire is used for the signal dreuits. 16 c.p. 110
e used for signals, and as the signal boxes are triangular, the
eea from almost any position.
tps are used for out-bound, and the green for return ears.
m ol the system is as f olfows: The conductor of a ear leaving
a terminal out-bound, first throws the switch marked
"Throw on." This lights the five lamps in the red boxes in
he eeetlon ahead of him, and he proceeds to the first turn-
at, and, if there is no green lamp burning at that place, he
lirows off the red signals behind and sets the red lights in
le flection ahead.
If a lamp should bum out whfle the oar is running be-
Teen turnouts, warning of the fact is given by the absence
(he red. ViAt. and by watching the green signals the motor-
in can teuwnen a car is coming in the opposite direction.
If the out-bound car, coming to a turnout, finds the red
nal bumixuc for the section ahead, showing that the section
Toeupied by a car |poing in the same direction, it must
it until the section is cleared by the car ahead.
{lie sisnals nxay then be reset, and the car can proceed.
»uld a €srevr find that they are unable to li|^t the red
lals, thesr may use the reverse, or green signal, to the next
return the green signals are used in the same manner as
>r the red aisnals and an out-bound car.
boxes are placed about a car's length outeide of the ends
ill al wajrs approach at slow speed, which is quite desirable
;un>ou^.
ELKOTRIC RAILWAYS.
IMlleOrerhsKi.
■^".ts,:-
AKbor.
■"'"'
•Sir
^"^°*
Hain
Lino.
"So.
§
1
i
1
£
1
&
t
1
t
^
ft
t
i
j
No. OB. 4 9.
Ft.
Lb.
1«W
lOHO
B200
108B
SMS
«
J-
&V°i»„
"■
400
IM
IIDO
»
a
1
No.™ip«l
&.
TBI
3000
mo
ISO
801
801
800
18»
la
■»
400
«4I
»
1
Iitnnd
No-USgnj
Lb.
m
1B00
450
m
101
100
10
too
101
SSr. ; ; :
n
ao
»
'
■
«
S
«
M
1?
a Bt«k8i . . .
41
41
90
00
40
;
-
I
i
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3
3
,
Tn
If
1
On
vlD inguUEun
mbnoklee .
»
M
4fi
00
4S
'
^;^X- : :
J
t-lron breckota .
Cn
_
Li
M
M
45
144
4E
90
,f I?.^ br.ckBt»
Polei,lse'[I. Hparc .
m
4ft>
1
1
1
Boi
Bdj
m
-
;
i
Seotion twitch boiH
2
a
2
ffFANJ)ABS> IRON OR STEEL TUBULAB POLES. 629
TIMAn Ot COM! !rO PM01»VTOB Olf M MXIiB OF
JDOrBIX TAACK OVSltHBAD T]|OI«I«BY
COHMrBVCTIOH JPOR OXTY ftOnftSJETA.
(Report of BioD J. Arnold, November, 1002.)
too poles, set in ooncrete, at $28 $2,800.00
1»n iron erois &nns, with pina and ins., at $3 .05 . . . 107.50
nail Brooklyn insdAtora for spaas, at 50e 50.00
obe stnin insulators for spans, at 22o 22.00
wisfat line hangers, at 32io 20.25
xl-in hangens, at 50e. 5.00
jered &-ineh ears, at 16o 22.40
9 erofls-oven (estimated), at $3 36.00
listed eroaM>ven (estimated), at $6 48.00
y frofs (estimated), at $3. 24.00
6-16 inch galv. strand wire for spans, at $10 per M. 30.00
a plates (strain layout), at 32c 1.02
Brooklyn (strain layout) at 50c 6.00
insulators (strain layout) at 22c 2.64
-inch galv. strand wire (strain layout) , at $7 . 25 per M . 10 . 88
J hangers (2 double curve layouts), at 44c. ... 8.80
hangers (2 double curve layouts), at 35c. ... 7.00
nch strand wire (2 double curve layouts), at $.725 per M . 7 . 25
Brooklyn (2 double curve layouts), at 70c. 2.80
t troUey wire, 4246 pounds, at 13ic 562.50
n^eara. at50e 1.00
spans, trolleys, etc 225.00
sive of feeder wire $4,100.03
ire eetimated avenice per mile 4,000.00
$8,100.03
Oir OR VMHWMJL TUBlJIiAn POU8S.
or eJectrio railway lines are made up of the regular pipe
idord and extra heavy.
OS in oonunon use are :
lard tuhinm.
heavy tubing,
torn aeotion of extra heavy tubing, and other sections of
tCom and middle sections of extra heavy tubing, other
«re 28 feet end to end for side or line poles, and 30 feet
gfolem. Tlie standard joint insertion is 18 inches, and
ooloulAted from reguLar standard pipe list (see pages
Btion poles are most commonly made up of 6 and 5 and
* aidt^ or line poles; and 8 and 7 inch pipe for comer or
.^^6 sumI S and 4 or 7 and 6 and 5-inch pipe for aide
d O-inoJb for oomer and strain poles.
ELECTRIC RAILWAYS.
■taa^Bid Paid Use r*»tF«c«*^
For m«( nrbui and all tntemTbui or •iibnrbaii llnea, wnodsn poW u
(ueil.iuid are e<[hsroctii«oniDr iliaTad. Tbs folio vLng onti ihow oonimc
_.__ i__j_ .. J. ._^ j„j arrangmoDts of org** anna.bTackata,ata.
w
OBLE TRACK CENTER POLE CONSTRUCTION. 631
e rowlt IVB > ^e«tar dlAluio* bfltwA«ii trlMk ceoten „__
nee periDilKng «aater pole oomtruoilon, wltb Imt eoct p«t mlU
< nHd, altbonsb Iba latter 1« oftun preferred.
r In. &«■•'>«>«'
Aiis.
!yft:::«i
i:
5
na. 8. TTPloal Center Fole
E1,ECTB1C RAILWAYS.
PIMc B«K P*laB.
1\i
i%!
POLES.
633
By MorriB, Tasker, & Go. (Inc.).
lize.
Wrought Iron or
Steel.
Length.
Weight.
t .
T
( .
y .
5 in., 4 in., 3 in.
5 in., 4 in., 3 in.
6 in., 6 in., 4 in.
6 in., 5 in., 4 in.
7 in., 6 in., 5 in.
7 in., 6 in., 5 In.
8 in., 7 in., 6 in.
8 in., 7 In., 6 in.
27 ft.
27 ft
28 ft.
28 ft.
30 ft.
30 ft.
30 ft.
30 ft.
360 lb«.
60011m.
475 ItM.
70011m.
600 lb«.
1000 lbs.
825 lU.
130011m.
ITelg-lite IVrovflit'
IroM »nA 9te«l Poles.
i.
DiAmeter.
Weights.
5 In., 4 in., 3 in.
6 in.. Sin., 4 in.
6 in., 5 in., 4 in.
7 in., 6 in., 5 in.
8 in., 7 in., 6 in.
8 in., 7 in.. Gin.
360 lbs. to 515 IbB.
475 lbs. to 725 lbs.
510 lbs. to 775 lbs.
000 lbs. to 1000 lbs.
775 IbB. to 1260 lbs.
826 IbB. to 1360 lbs.
■Mc CoMtsMBte of ^^oodon Poles, la Toot.
Diameter.
Section.
Cubic Feet.
6 in. X 8 in.
Girenlar
7.36
7 in. X 0 in.
Circular
9.56
7 In. X 9 in.
Octagonal
10.1
7 in. X 9 in.
Circular
0.92
7 in. X 9 In.
Octagonal
Circular
10.46
Sin. X 10 in.
12.52
8 in. X 10 in.
Octagonal
Circular
13.2
7 in. X 9 In.
10.63
7 in. X 9 in.
Octagonal
11.21
Sin. X 10 in.
Circular
13.41
Sin. X 10 in.
Octagonal
14.15
9 in. X 12 in.
Octagonal
19.06
ItAko of Polos.
em should be giyeu a rake of 9 to 18 inches away from the
>r steel poles set in concrete need be giren but 6 to 9 incheB
poles, ana those supporting cunres, should be given additional
aroly guyed.
634
ELECTIUC BAILWAYS.
POVMOII.
xev*
Kind.
LiTeoak
White oak
Bed oak
Chestnut
Southern yellow pine
Northern yellow pine
Long-leaf yellow pine
Norway pine
Spruce «
Hemlook
Conditien.
Perfectly dry
Perfectly dry
Perfectly dry
Perfectly dry
Perfectly dry
Perfectly dry
Unaeaioned
Perfectly dry
Perfectly dry
Perfectly dry
Weightper
Cubic Foot.
48
as
41
45
94
as
46
36
95
The weight of green woods may be from one-fifth to one-half greater than
the weight when perfectly dry.
(MerrUL)
The following tables give the dip of the spaa wire in inches under ttie
combined weight of span wire and trolley wire, for yarions spans and strains.
I/ength of trolley wire between supports, 125 feet. Weight of trolley
wire, 319 lbs. per 1000 feet. Weight of span wire, 210 lbs. per fiOO feet.
illMrl* Trollej irira.
Spans in
Strain on Poles, in Pounds.
Feet.
600
800
1000
1600
2000
2600
8000
80
7.8
4.9
3.9
2.6
1.9
40
10.6
BJ6
6.3
8.6
2.7
60
13.6
8.5
SM
4A
3.4
2.7
00
16.7
10.4
8.3
6.6
4.2
3.8
2.8
70
19.9
12.4
9.9
6.6
4.9
4
3.8
80
23.2
UJH
11.6
7.7
6.6
4.6
8.9
90 •
26.7
16.7
13.4
8.9
6.6
5.8
4.5
100
80.8
18.9
16.2
10.1
7.6
6.1
5.1
110
3i
21.3
17
11.3
8.5
6.8
6.7
190
87.9
23.7
18.9
12.6
9JS
7.6
6.8
Vwo Trolley -VTlrea, lO Fetit JLpmrt,
Span in
Feet.
Strain on Poles, in Pounds.
600
800
1000
1600
2000
2500
3000
8500
40
15.4
9.6
7.7
6.1
3.9
3.1
60
20.8
13.
10.4
6.9
6.2
4.2
60
26.8
16.4
13.1
8.8
6.6
6.3
4.4
70
31.9
19.9
15.9
10.6
8.
6.4
6.8
80
37.6
23.5
18.8
12Ji
9.4
7.6
6.3
5.4
90
43.6
27.2
21.8
14.5
10.9
8.7
7J
6.2
100
49.6
30.9
24.8
16JS
12.4
9J9
8.8
7.1
110
65.6
34.7
27.8
18Ji
13J
11.1
9.3
7.9
120
61.9
38.7
30.9
20.6
IBA
12.4
10.8
8.7
KOTB. — See also chapter on Oondtteton.
For tahU of atranded wire for tpam ctnd guyt tee p<ig€ 200, PropertUM
qf Conductor 9.
SIDE BBACEET8.
635
i|NiH WIrct should be stranded galvanuied iron or steel, stses i ineh
diameter A* jLor | inch aooording to the weight of trolley wire, ete.. to be
supported. Where wooden poles are used it is not neceMary to provide
otoer instdation for the span wire, and the wire can be seeured to we loop
of an Qr»>bolt that ia long enough to pass through the pole at a point from
twelve to eighteen inches below the top, and that has a long thread to allow
taidng up abek. Where naetal poles are used it is necessary to insulate the
span wire from the pole. This has been done in some cases by inserting a
Jong wooden plug in the top of tubular poles, capping it with iron, the wooden
plug then being provided with the regular eye-bolt. The most modem way
18 to provide a good anchor bolt or clasp on the pole, then insert between
the s^n wire and this bolt one of the numerous forms of line or cirouit-
breanng insulatore devised for the punxwe. If the anchor bolt is not made
for taidng up slack, the insulating device can be so designed as to be used
as a tuniDuckle. Of course insulation must be provided for both eilds of
the span wire.
Span wire must be pulled taut when erected so that the sag under load will
ie a minimum. Height above rail surface should be at least 18 feet after
he trolley wires are in place. This height is regulated by statute in some
tates, and runs all the way from 18 to 21 feet.
Btd9 JBracbets. — Along oountiy roads and in such places as the track
' along the side of the roadway or street, it 14 customary to use single poles
ith side braekets to support the trolley wire.
Where side brackets are used it is not safe to place the pole less than four
et away from the nearest rail, and to give flexibility to the stranded sup-
10. Single Suspension.
For Wood Poles.
wire, ndv alwasrs provided for the tToUeiy wire, the bracket should
enough to reach the distant rail, thus giving a little more than two
table for flexibility. A common length of bracket is 9 feet.
B0 lO and 12 show the simple form of side bracket in most general
f*i0B. IX and 13 show vaciataons of the same. It is obvious that this
of aupport may be made as elaborate and ornamental as may be
2ble-track roada cerUer-poU construction in sometimies used, in which
plaoed alons the center line between the two tracks, ana brackets
fa OMi Btujh. aide of the poles overhanjging the tracks. Where wooden
used a ipood form of construction u to bore the pole at the proper
i run tlux>ush it the tube for the arms, this long tube being properly
botii aides of the pole by irons from the pole-top to the bracket
y braeee a^ainat Uie pole. The trolley supporting wire can extend
to end OS the brackets throuph the pole, or can be cut at the
eye-bolts be used, aa in the side-braeket construction shown by
636
ELECTRIC RAILWAYS.
VM
Fzo. 11. Sini^e Siupeosion.
For Wood PoI«B«
Fig. 12. Single Suspension.
For Iron Poles.
^•^A
Fio. 13. Single Siupemrion.
«For Iron Poles.
TROLLEY WIRE SUSPENSION.
637
14 mnd 15 illustrate simple fonns of oentei^pole braokets.
Fio. 14. Double Suspeosion. For Wood Poles.
pole eonstruetion b quite often used on boulevards in cities, where
and poles can be made quite ornamental.
Fio. 15. Double Suspension. For Iron Poles.
OMJLBY -WEMX ftVAPBliAlOlV.
of th« trolley wire along straight lines is
er and needs no explanation; at curves
! have been some simple forms developed
that are handy to have at hand . Following
of the points:
fcl maacliomic«. — Sin^e track. See
_ —See Figs. 17 and 18. To be
foot of all grades, at the top of hills,
, three (3) per mile is good practice;
i.re frequent th^ will afford all the
ry.
Fig. 16.
Tta. 17. single Traek.
FlO. 18. Double Track.
ELECTRIC RAILWAYS.
CBrT«a, llaaHBclMi. Mid ea^B.— The nupvnilan of tha trollaj wire
■IcurreilgcumpllcKted or afinple, SMOrdlng utbs truck ms]' bs tingle or
iloabls, or tbe corrs majr be at ■ iinHaliiE or a clmpJe carre. Below an
(katghea of aeTeral typw nt foapenitan Tor dlSereiit tormt ofcunea, tor
■ln(le and doable trai^, for oruai autpeualoa, and for center-pole oonatniB-
Single Track, Obtnae AngU.
le Track, RIgbt-angle Fio. !
^
TROLLEY WIRE SUSPENSION.
639
aft. Single Track Grossing,
Cross Snnpeiision.'
FlO. 25. Single Track Crossing,
Cross Suspension.
i^a, muip«MiiOM, AMdl C^ojs. — Simple crossings of
mplication In the suspension of the trolley wires, when
tracks
QO oomplication in the suspension of the trolley wires. When cnrres
Ided to connect one track with the other, compHoatlons begin, and
double tracktt cross double tracks, and each is oonneeted to the other
'yes eaeh way, the network of trolley wires becomes very complicated.
» are sketches of a couple of simple crossings which will clearly
;h illustrate the methods of suspension commonly used.
CROSS SUSPENSION WITH GUARDS
FOR TROLLEY WIRE.
Fio. 2a
Where trolley wires are used in cities or in any location where there are
her oTerheM oonduotors liable to fall across the trolley wire, it is custom-
T to place svird wires parallel with but above the trolley wire, as shown
1 the aboTe sketch. A piece of No. 6 B. ft 8. galranised iron or steel
640
ELECTRIC RAILWAYS.
wire is drawn taut abore the regular suspension wire ; porcelain InsulatorB
are secured to the same at a point about a foot or 18 inches either side of ti&e
trolley wire, and through these insulators is threaded and tied a Ko. 10 gal-
▼uiised iron wire. This guard should be broken at least every half-mile
where it is in any great length, as it is not advisable to have it a oontinuoos
conductor for any great distance, and it is advisable to avoid its use where-
ever possible.
AXVS]lliATUI« CVlUftBirT IKAULlirAYS.
Abstract of O. E. Co. Bulletin, Kev., 1997.
The radical departure in the design of trolley line construction made
necessary by the advent of high tension alternating current distribution
for electric railway operation naa resulted in the catenary system of line
construction, which while providing ample insulation surface for the high-
ii
0
4- -/
t z
z -,^z
J^ ~fev
U Zl&L
w^ wL
ih Hrtfi^
vV \i^y
iJLjm'^
~yu A
^/ \y
7 ^
2^^"^
2
.« .04 M >oa 'fo jz
7?h7e ^co/?cfs
S4 J6
Pio. 27.
est potentials used or contemplated, also incidentally affords marked me-
chanical improvement which is important with the high speeds of modem
suburban and interurbau operation, and steam railroad electrification.
The catenary system which is equally applicable to bracket or cross span
construction, consists essentially of an arrangement of a slack messenger
CATENARY TROUiEY CONSTRUCTION.
641
cable and Builable bangers ao distributed as to maintain tbe trolley wire
practically without sag between BuspeuHlon points, or to limit the sag as
may be necessary tor various conditions of operation. ^ . ^.
Ae blow of a collector passing suspension points at high speed Is thus
creatly reduced. The shorter distance between hangers necessitates lees
Stress In the trolley wife and reduces danger of break in the line.
The catenary system, therefore, offers the meehaiUcal adjantages of a
longer pole spacing and a flatter trolley wire, and a flexibility in the lino
whteh obviates the hammer blow of the eolleetor at suspension points, and
rodnooB danger of inefthaBi*??-^ bipeakaf e.
The three-point su^>ension in wmch, with 150 ft. pole spaefag, the
.^
^
i
5
:^oao
ieoo
i600
i4ao
iZOO
iOOO
eoo
zoo
o
/40
iOO
%
60
40
ZO
O
'4Q
I
«
y
dJ
^n
f\
\
^
\
•^
X
/
\
>.
si
•J
f-
s
''J
J
^^iS?
I
i
f Ji
> :
S 4
t ^
5 e
^ :
r <;
> £
^ /
0
_
Dff/ec6/on /r?c/?e^
Fia. 28.
Isangers are 60 ft. apart, has been found ample to maintain a sufBciently
leTol trolley wire for operation with wheel collector at speeds up to sixty-
fi-FO miles per hour. A new element is, however, introduced by the sliding
pantograpn or bow trolley which, on account of its great inertia, requires
sb closer spaolng of the trolley support.
t\%, 27 shows comparative curves of time required for vertical vibration
of wheel and pfuitograph trolley respectively. It has been found that an
^leren-point suspension renders the trolley wire sufficiently level for the
p^latiTely slug^lish action of the pantograph collector. This brings the
^ers 13.6 feet apart, and for all operative conditions with sliding colleo-
the eleven-point suspension is recommended.
'F\%. 28 shows the effect of temperature variation on sag and stress in
ley wire with the three-point construction.
642
ELECTRIC RAILWAYS.
Bt—t Strand.
Common galyanised strand ia not recommended for any purpofle In oat*
nary constmction, and wherever steel strand U used it should be one of the
three special grades, properties of which are giyen in the following table.
Plijsical Propertlea of Scvom Wire Kxtra CtelTaateod
Steel Strand.
EXTKA OALVAiriZBD SIBMEKS-MABTIK STBAITD 90,000 PER SQ. IN.
Diameter. atJ^JllZ 'rVT^tf Elongation. Lay.
Tensile
Elastic
Strength.
Limit.
3060 lb.
18301b.
48ao '*
2910 «♦
6800 "
4060 *«
9000 "
5300 «*
11000 •*
6600 ••
19000 "
11400 "
8"
4"
ExTBA Qalyanized Hioh Stbbnoth (Cbuciblb) Steel Stbavd.
Diameter. a*-^^K Vi^iT Elongation. Lay.
ft
Tensile
Elastic
Strength.
Limit.
6100 lb.
3316 lb.
8100 "
6266 "
11600 "
7476 "
16000 **
9600 **
18000 "
11700 "
26000 "
16250 '•
6^
ExTBA OALYAiriZBD EXTRA HlOH STRENGTH (PLOW) STEEL STBAVD.
Diameter. ar.'LT^K TnT^iV Elongation. Lay.
f
¥
Tensile
Elastic
Strength.
Limit.
70001b.
5700 lb.
12100 ••
9075 "
17260 "
12930 "
22B00 "
16800 ••
27000 "
20260 "
42000 "
31500 "
4"
i*"
6"
0"
For ordinary conditions, the messenger cable should be of .V' extra gal-
▼anlaed Slemena-Martin steel. For puU-offs \*' cable is satisfactory, and
for general guying purposes |" extra ealvanlzed Siemens.MartIn strand Is
generally recommendea. Special condttions may call for " high strengtii "
cable, but as this cable requires mechanical* fastenings on account of its
stiffness, it should be used only where absolutely necessary.
1
CATENARY CONSTRUCTION.
643
LIM Maltitol per ■!!• wT
ComstractlOM.
t<mr Cmtmmmrj'
ID viro m«Mttiger
tngKM
lia iof nlAton
okdtf
datorplof
leofer fotnlftton . .
uigen
(UUVfttV
ngsri
iDfSIl
uiffn
\gen
logen ,
agen
g Bleerm
hMMtgen
eje§
tambneklei
sJamps
SiiifU Track.
Braeket
Ooiuitrao-
tlOB.
S
Point
4
86
W
86
36
68
11
Point
tor cnnrM,
gs, He,, depen-
pon Joonl oon
3
4
2
4
lalaton.
ice emn.
rhangen
' hmngerm
!gefs
DnokJes
Mtara ..
tofv. . . .
BriBit
8
8
d trolley
BrstrAiid
itnuMl ..
6800
64S6
1400
36
72
72
72
72
72
8
4
2
4
OroM Span
Oonttmo-
tion.
Double Track.
8
Point
86
80
11
Point
80
Center Pole
ConBtmc-
tion.
8
Point
8
8
S300
5400
1400
8
4
4
2
88
72
tarn
6400
2600
72
72
72
72
72
8
4
4
2
88
88
72
6800
B400
8
72
72
72
72
186
11
Point
Crow Span
CoAitmc-
tioni
8
Point
8
72
72
72
6
8
4
4
72
5800
5400
72
144
144
144
144
144
6
8
4
4
72
5300
5400
2600
8900
72
11
Point
72
72
136
6
8
8
4
72
144
144
144
144
144
6
8
8
4
72
10600
10600
2600
3200
88
88
72
10600
10600
8600
644
ELECTRIC RAILWAYS.
•<anr«rtii0i VdoU^jt for mitaamg tUmmtmmi*
Where a Blldlng oolleotor ia to be used, it Is recommended that the tan-
gent line be sta^ered by means of steadv braces in braclcet construction,
or pull-off, in sjMui construction, to avoid wearing grooves in the collector
contact surface.
For this purpose the trolley wire should be displaced approximately eight
inches on eaeh side of the center line of the track every 1000 ft., i.e., there
should be one complete wave from the extreme position on one side acroes
the track and back to the extreme position on the same side in each 2000 ft.
of line.
When the road bed is new, it is well to simply make provisions for stag-
goring the trolley wire, but to defer actual staggering until the i^ad bed Is
settled and put in final shape, as the sway of the car due to irregularities in
the track may be great enough to throw the sliding contact enurely off the
wire.
llmcket ConatrvctloM.
After the poles are installed the brackets should be located at a height
of sixteen inches more than the required distance between the top of the
rail and the trolley wire. This allows for two inch sag of the bracket due
to the yielding of the pole when loaded, In single track construction. For
double construction tnis distance should be fourteen inches greater than
the desired height of trolley above top of rail. The messenger wire should
next be adjusted for tension to jAre a sag at the center of span of about 9
inches at 90'' F.; 10 inches at 00» F., and 11 inches at 86^ F.
Spaa ConatractioM.
In span construction the span wire should be installed so that when the
weight of the messenger and trolley is put on It, there will be a sag of at
least three or four feet between a straight line drawn through the pomts of
support of the span wire and the point on the span wire where the mes-
senger hanger is attached. When unusually Ions distances are necessary
between the poles the sag should be greater. The back guys should be
insulated for full line potential.
Fig. 29. Catenary Coufltruction. Single Track Bracket.
^
CITEMABY CONSTRUCTION.
645
Fie. ao. Catenary Conitmotioii. Doable Track Span.
ai. Catenary Curve GonBtmotlon Using Steady Brace.
Spreader Cnnre Construction.
646
ELECTBIC RAILWAYS.
FiQ. 8S. Oatenary ConBtmotlon. Street Corner.
MiCIMfftll of
(ipAM for
ELXYSK-Ponrr Gor^stbuctioh.
Length Pole
Spacing.
Polnte.
1
41"
2
6i"
2
9"
10'
\\\"
12|"
14"
18*"
17J"
2
2
• • • •
• • ■ •
2
8
181^'
Number of hang-
era required.
160 ft.
11
9
8
7
6
6
4
2
1
• • • •
2
• * ■ •
2
2
2
• • • •
2
125 "
2
• • • •
8
• • ■ V
2
2
2
110 **
•
96 "
80 '*
70 •'
66 "
Thbks- Point Ck>MBTBUcTioK.
160 ft.
8
8
8
3
3
2
2
1
2
• • • •
• ■ « •
2
2
• • • •
1
• ■ ■ •
• • • •
• ' • •
2
2
125 "
1
110 "
1
■ ■ • •
• • • •
1
95 '*
80 **
• • • •
70 *•
• ■ • •
66 **
2
CATENARY CONSTRUCTION.
647
e
3
i
0
9
1
&
o
h
I
I I
I!
I
s
!
t
I
I
-a
00
^
ST
CJW'*
C4
04
e«e«e4
«
eoci
64 00
e«
OMeteo^
liSi^gi
o
H
Q
P
09
5
O
flu
ill
H
M
39
H
1 |e«e««
<N« 1
FN •
• 1H •
FN •
e^MMco'^
pg^i
iii
I
I
I
I
I
li
ll
ELECTRIC RAILWAYS.
■■Whe™ Uma or more tracks sre squip^ u on the New York. Hew
tlavMi 1 Hutford Rjutrokd, (ho ticdim' wire ii ncervlly supporled [nun
two catetury nblea, which are c»rnec] on fltovl ondfo. pJaoed 300 feet
■part, Uaavier bridgn an uud at intflrvala to aooEor the lyglMn, uhJ
viewi of one of tbCM uohor bridga are ibowD io fi^, 34, 35, and 3t.
1 view of BridtarwSupHirtWCbtenBiyHuiii Trolley,
BLBCTBIC RAILWAYS.
Plui View u[ BdiloB (ai Supporling Cktcury Hunt TroUgT,
N.Y.,N.U.AH. R.R.
CiTENABT CONBTBUCnON.
651
,^
Fio. 37. Detail of Oat«iiary GonttnMtion, Spendenfekb LiiM.
I. T-Iron Bracket with liain Infulator and Steady Strain.
» 4l«Telopmeikt of the A. C. notor 1b in no way handicapped br
*lie teoflew oonstmetion to withstand high potential, as A. C.
'vrorKed inoceufuUy at 10,000 volta and 16/100 Tolts.
Ofi2 ELECTRIC RAILWAYS.
wrsBov coNsmiPVKOit.
■■•war Cbfwwi For nnvsnicnn) in quiokly BsocrtBiaini tha hora»-
powflT nauind to propd & nr oF knovij wdK^t under known otjnditioiia of
■pMd luiil inulg. ths ourvs uliawn below have been olouLiiIed.
The Mlrb^Bd portion of Che loner horiioaMI line repiwenU tha epeed in
milea per hour; the rigbt-hand portioa of nine line, tha h.p. per car; th«
oblique linea in left-hand side of cut. the per cent grade aa marked on each
line ; the oblique hnn on ri(bi-hKnd side of out, the w«i^( of car u marked ;
whilo the verticnl liae in center of cut repreeentj tha h,p. per ton. Tbi«
curve ii based upon a flat friction rate of 30 Ibe. per ton TsiWO Un.) for all
E
1
H0R8K-POWXB OV TBACTION.
653
11
HI
11 P8 %%% |s?S III |M %%% 8.1
iHiHiH fHdc^ e^cieo eoeoeo 'ifi'^ lOiott «ei*
%m IIS iig i§§ §11 m s§
*^^^ i-iiHe« e«««e>< e4e»m toco^ ^o4D ««
if ii
III iiy §11.11 IP i§iip ip ^1
^^^ ^i-4«H efefct 04MC) ncin ^^^ loia
«
i§ m m m m% iii is
^ lH*-liH i-lfHCI 00404 CIMCO COCO^ ^V
f
is^ m ill 111 iiH ps 111 III ^1
. ^T^^ iH«Hi-i «-ic4c« eieim eicow «q^
9i
s I III Hi ill i§s ill i§i i^i 188 88
y 91-! <^«i^ •f^* «q« »?*Z Sa^S ^^9 ^^^ R8
I *•<*■* <^^iN «"<i»<th «e4e< www ww
¥ I ill ill ill lis ^SS ^SS SSS3 98P S8
¥ ^•n «?»?'T "^^fct ««« ^.»«( ^^^ 00^^ ^^i: ^^
I *^ »-ir^i^ ^ii^^ ««vNe>i eteiw weo
ijili ii. Ill ill i§§ ill III 11^ ii
I «i4<^^4 ii4r4»H V4lHVi4 WWW WW
f IP sp III PI III ill III III II
9^ v^f^fH vHT^r4 r^F^W WW
nil
11 §ig i§g SI
•^w
§888 8Sg} 88|
111 ill §ii i§
t»
A • • • ^
8^
gl
'I
5oS
i§S S§§ S§S III §§| i§
^«>««i4 «^^M v«ww WWW wnm m9
• •• ••. ••• ••• •)« ,*
o
I
«-i^w ^«oeS* "^i^ie i?<o^ »>?oo a8*akO i-iwn ^^
;jr:ir2000 sin «). W=Load in tons. n = Speed in milee per boor,
.OO9^(Kj=4S000iltt«). X^=Reil0Utieeln lbs. per ton. ^=^
( of po-«rer reqnired^tfifmoTe oma ton ok lieyxl ftt speedi in
eh Jr=: lO.
9 of j\.i>i>iTiOKAL POWEB required to raise OKB ton ov
»i]<l at speeds given. *
P. reQnired on letblb alone for speeds glren.
juSditional on obadxs alone for speeds and $^^teB.
■ total BC. P. required.
O-l ven a motor ear, total weiffht 9 tons, to aseend a 7 per
speed of six miles per bonr. wbat Is tbe estimated borsc^
wltb Jr=:301b«.?
654
ELECTRIC RAILWAYS.
H for 6 milM per hoar b . 16, which, multiplied by 0 X t^, - 4 . 33 h.p., in
oyeroomins the track resistMicee alone.
H' — 2.240, which, multiplied by 0. '^ 20.16. The eum of the two wfli
mve the total theoretical, i.e., 24. 48 h.i>. required. Allowinc 50 per eent •■
the eombined effidenor of moton and geannc to operate ^U car would
require a draft of 48.96 h. p. upon the line.
OV TMAGTIOir. (Dayis.)
Speed in Milei per Hour.
4
6
8
10
12
15
20
25
30
35
40
50
60
Horse-Power Required to Propel One Ton at Various Speeds up
Various Qrades.
0
.32
.48
.64
.80
.96
1.20
1.60
2.00
2.40
2.80
3.20
4.00
4.80
1
.53
.80
1.07
1.33
1 60
2.00
2.66
3.33
4.00
4.66
2
.74
1.12
1.49
1.87
2.24
2.80
3 63
4.66
5.60
3
.93
1.44
1.92
2.40
2.88
3.60
4.80
6.00
4
1.17
1.76
2.34
2.93
3.52
4.40
5.47
5
1.39
2.08
2.77
3.46
4.16
5.20
1
6
1 60
2.40
3.20
4.00
4.80
7
1.86
2.72
3.62
4 53
8
2.02
3.04
4.05
•
9
2.24
3.36
4.48
10
2.47
3 68
4.90
•
11
2.67
4.00
12
2.88
4.32
13
3.09
14
3.29
■
15
3.52
Nora No. 1. — The h.p. required to propel a oar equals the total weight
of oar plus its load (in tons) multiplied by the h.p. in table eorrespondinc to
assumed srade and speed.
F. E. IdeU, M. E.
Track. — To start car 116 lbs. per ton.
To keep in motion at 6 miles per hr. 15.6 lbs. per ton
Track. — To start oar 135 lbs. per ton
To keep in motion 32 lbs. per ton
•s. — To start oar from 0 to 6 miles per hour . 284 lbs. per ton
ayerace, 264 feet per minute.
TBACTION.
655
(Davis.)
Load of Trailer Gars in Tons which a Motor
^%t cent
Grade.
Tnotire Foroe
In PoandH
per Ton.
Car of one Ton will Haul.
Snowy Bail.
Wet Bail.
Dry Bail.
0
30
8.50
12.33
16.00
1
60
4.70
7.00
9.00
2
70
8.07
4.21
6.14
Z
90
2.17
3.44
4J{5
4
110
1.60
2.63
3.54
5
130
1.19
2.07
2.84
6
150
0.90
1.66
2.33
7
170
0.70
1.35
2.00
8
190
0.50
1.10
1.63
9
210
0.36
0.90
1.38
10
230
0.24
0.74
1.17
11
260
0.14
0.60
1.00
12
270
0.05
0.48
0.85
13
280
Wheels slip.
0.38
0.77
14
310
• • •
0.30
0.61
15
330
0.21
0.61
16
360
0.14
0.43
17
370
0.06
0.35
18
390
0.02
0.28
19
410
Wheels slip.
o.:a
ao
430
• . *
0.16
21
460
...
0.11
22
470
• a .
0.06
S3
i
480
• ■ •
Wheels slip.
K l!io. 1. — Maltiply figures in table by
weight of trailer (in tons) that said
aggrades.
weight of motor ear (in tons)
motor ear will haul up eorre-
XO BEAKS VAREOVS
Miles per Hour.
>r
4
6
8
10
15
20
25
30
40
Feet pdr Minute.
/ 176
352
528
704
880
1320
1760
2200
2640
3520
»
06
84
112
140
210
280
360
420
560
1 26
62
78
103
129
194
258
323
388
517
' JM
48
72
96
120
180
240
300
360
480
22
46
67
90
112
168
224
280 '
336
448
ao
41
61
82
102
153
204
265
306
406
19
37
56
75
93
140
187
234
280
374
le
92
48
64
80
120
160
200
240
320
656
ELECTRIC RAILWAYS.
POWSm AE^ilJUB
B]» vol
TR170]
OAllA.
Wattmeter placed on car.
(MeCullooh.)
•
<
Average Watt-hours per
Car-mile.
Average Speed.
Miles per Hour.
Average Watts, per Seat
Capacity.
Averase Watts per Ton
(car empty).
Average Watt-hours per
Cai Mile per 1000
Passengers.
Double-truck car. Seats
36 ; weight, 11.75, tons ;
average for entire day
12040
1334
9.03
335
1025
5.9
Same as above. Average
for heaviest trip . . ,
13080
1412
9.25
335
1025
fiingle-tnick car, no
trailer. Seats 28;
weight, 8 tons ....
8471
921
9.20
303
1060
Single-truck car. Trail-
ers operated 26% of the
time. Average for the
entire day
9400
1110
8.42
264
1068
IS
81ligle-truok motor and
open trailer. Seats,
63; weight, 10.5 tons.
Average for heaviest
trip
12680
1440
8.84
201
1208
Meaio for DetorminAttoM of Power Roqalrocl for
Opersitloii of Utroet Rallwaya.
„ jy Pounds torque X R.P.M.
^'^' 5252
H.P. -^
Pounds traction eflfort X M.RH.
0.376.
Pounds
tractiv
efifort
'.^* I ^ Number gear teeth X 24 X gear efficiency X pounds torque
f. } Number pinion teeth X inches diameter of wheels.
Miles ( _ Inch diameter of wheels X number pinion teeth X R.P.M.
r Hour, j "" 336 X number gear teeth
Assumed — 3 miles per hour speed on curve, 4 ft. 8| in. gauge.
KILOWATTS ON GRADES.
Pomb per V9m for lA Toa Car.
667
Grade.
Speed — Milee per Hour.
i'erct. I i 1 1
1
6
8
10
12
14
16
18
20
0
1 15.03 16.11
15.24
16.42
16.06
16.95
16.29
16.09
17.14
17.64
1
35.03 36.11
35.24
36.42
36.66
36.96
36.29
86.69
37.14
37.64
n
46.08 46.11
46.24
46.42
46.66
46.96
46.29
46.60
47.14
47.64
2
6603 66.11
66.24
66.42
66«66
66.96
66.29
56.69
67.14
67.64
H
66.03 a6.11
65.24
86.42
66.66
66.96
06.26
66.60
67.14
67.64
?
75.08 76.11
76.24
76.42
75.66
76.96
76.29
76.69
77.14
77.64
H
86.03 86.11
86.24
86.42
86.66
86.96
86.29
86.69
87.14
87.64
r
96.03 96.11
95.24
96.42
96.66
95J96
96.29
96.69
97.14
97.64
{
116.03 115.11
116.24
116.42
116.66
116.96
116.29
116.69
117.14
117.64
t
136.03 135.11
136.24
136.42
136j66
136.96
136.29
136.69
137.14
137.64
/ 156.03 155.11
156.24
166.42
156.66
156.96
166.29
166.69
157.14
167.64
175.02 176.11
175.24
176.42
176.66
176.96
176.29
176.69
177.14
177.64
106.03 106.11
195.24
1S6.42
196.66
196.96
196.29
196.69
197.14
197.64
/ 215.03 216.11
^ 1
215.24
215.42
216.66
216.96
216.29
216.69
217.14
217.64
KIXOWATTS OM «RA]»lUi.
nieiuvred Knpat to Car.
IS VoB Car. Eaorgy
Speed — Miles per Hour.
6
8
O/ 2.19/ 3.31
4/ 5.07/ 7.06
9/ e.52\ 9. so
W 7.96/12.00
9.41/14.15
flO. 85/16. 30
ri2. 30/18.50
13. 75/20 - 70
ie.e5\2S.GO
\9.e0\29.40
n . 48 33
*.5. 30/38
8.30/42.50
1.10/46.70
SO
10
4.46
10.25
13.15
16.00
18.90
21.80
24.70
27.60
33.40
39.20
45.00
50.80
56.50
62.10
10
12 14
5.67
12.90
16.50
20.10
23.70
27.30
30.90
34.60
41.80
40.10
56.30
63.50
70.70
78.30
6.92
15.60
19.90
24.22
28.60
32.90
37.22
41.60
50.30
58.00
67.60
76.30
85.00
95.10
8
18
23
28.
33.
38.
43.
48.
58.
69.
79.
89.
99.
109.
25
35
42
50
60
60
70
70
00
10
20
30
40
80
16
18
9.65
21.20
27.00
32.80
38.50
44.30
50.10
55.80
67.40
78.00
00.50
102.20
113.80
125.8
11.15
24.10
30.62
37.20
43.70
50.20
56.70
63.20
76.20
89 . oU
102.50
115.30
128.50
141.50
20
12.75
27.20
34.40
41.70
48.90
56.20
63.30
70.60
85.00
99.40
114.00
128.50
143.00
157.20
.ble is baaod upon an average eflSciency of 83 per cent for the
n^. Tlus efficiency is assumed flat for all loads, hence giving
tilg^ for tlio low kilowatt oar inputs and slightly low for the
658
ELECTRIC RAILWAYS.
Power CoasM
■iptlOM. fleh«d«le
36 Tmm C»r.
Stops per Mile.
KUowatts.
maximum Speed.
Total Motor Oapadty.
0
20
26 m.p.h.
143
.2
36
29
176
.4
44
31
186
.6
61
33
207
.8
63
37
245
1.0
79
43
301
1.2
100
51
396
The energy values given in above table represent input to the car not
including any line losses. The mifc-rimiiin speeid values represent nnm-giwmnri
speed reached during the run. Motor capacity is based upon a temperature
nse of 00° C, above surrounding air, taken at 25** C, after a full days*
at the schedule of 26 miles per hour noted.
run
PoMlble Acbedwle wttb 46 1H.P.
Wmwjim^ Wr^^mmmcy mt Atopa.
Maxim
36 Vaa C
Schedule Speed.
Kw. Input.
Number Stops per Mile.
46
106
0
40
101
.18
36
97
.40
30
93
.70
26
87.6
1.08
20
84.
1.80
HO. or CAS3 oir tsm bhi^sa
0173 3PKMM AMD H
OF TRACl
VAmx-
Minutes
Apart
Average Speed in Miles per Hour.
or
H*dway.
6
7
8
9
10
12
15
20
25
80
1
2
10
16
20
ao
100
60
33
26
20
17
14
18
10
7
5
8
86
44
29
22
17
14
12
11
9
6
4
3
75
88
26
19
16
13
11
9
8
6
4
8
67
88
22
14
13
11
10
8
7
4
8
2
60
90
20
16
12
10
9
8
6
4
8
2
60
26
17
13
10
8
7
6
6
8
8
2
40
20
13
10
8
7
6
5
4
8
2
1
30
15
10
2
2
1
24
12
90
10
Note. — Fractions above one-half are considered whole numbers,
fractions below one-half are neglected.
VABIOVB SPEEDS. , 659
TDffitaEDlbtDDDb«rof flATfl Toqulrvd tooparmt« ubj length n»d| lUrld*
Uw lonlHr Itllid In Ihe table ludgr tha dcairsd BTsraie ipeed Hud bud-
njft^MD, udmiilUplrbT Cha length irf theriMdln qiuitiOD. Shonldll
660
ELECTRIC RAILWAYS.
Formula: —
Let n — number of oars required,
m — miles of track.
S «- average speedu in miles per hour.
/ a interval or headway in minutes.
m X 00
Then,
n
S X I
, AXMB TOTAJL NMJMMM]
CAJRft.
Total number of oars on a given length of street on which cars are running
both ways » (length of street X 120) -r (headway in minutes X speed in
miles per hour).
PER HOVJft nV rBBV PSR MIMCTB
Alf]» Pfili SBCOim.
(Merrill.)
Milee
Feet
Feet
Miles
Feet
Feet
per
per
per
per
per
per
Hour.
Minute.
Second.
Hour.
Minute.
Second.
1
88
1.46
16
1408
23.47
2
176
2.94 1
17
1496
24.93
3
264
4.4 '
1
18
1584
26.4
4
352
5.87
19
1672
27.86
5
440
7.33
20
1760
29.38
6
548
8.8
21
1848
30.8
7
616
10.26
22
1936
32.26
8
704
11.73
23
2024
83.72
0
792
13.2 1
24
2112
35.2
10
880
14.67
25
2200
86.67
11
968
16.13
26
2288
38.14
12
1056
17.6
27
2376
39.6
13
1144
19.07
28
2464
41.04
14
1232
20.52
29
2552
42.60
15
1320
22
30
1
2640
44
RATING STREET-RAILWAY MOTORS. 661
STRSKT.AAU.HrAT MOTORS.
(CondeMed from W. B. Potter in Street Railway Journal.)
^otJi^^P«ntnntdteroM hoar's run under rated full load not to ex-
Md75°C. ', room being assumed at JB® C. Average load for a day's run
lonld jiot«zoMd90per cent of its rmted fuU load, whloh wUl give a rUe of
mporature of about 60OC. » — v
The Above ratings are based on a line potential of SOOyolts. but the aTer-
B performance can generally be increased in proportion to the increase In
8 roltage; that is, a motor will do approximately 10 per cent heavier
wee for tbe same temperature rise when operated at 650 volts.
nth electric brakes, motors must have increased capacity, as heatine
wses 20 to 25 per cent. The aO per cent increase is on roads having few
les and stops, irhile the 26 per cent is on hilly roads with frequent stops.
iproxtiDAte rated horse-power of motors =
Dtal weight of car in tons) x (max. speed In miles per honr on level).
5 ■
' eqoipmenti with electric brakes, divide bv 4 instead of 6. When
niun speed is not known, it may be assumed as twice the schedule
laiple It
car (loaded) X 60 m. p. h. ,,^ ^ , .^ ^
g = 200 h. p., or four 60 h. p. motors. In
le, if the line pressure were raised to 600 volts, electric brakes could
on the equipment by changing the gear ratio so aa to have the same
un speed.
>r (loaded) x 25 m. p. h. „. * *^,
g = 66 n. p., or two dO h. p. motors,
ules indieate minimum capacity under ordinary conditions.
Timcttv* Sir«rt.
' ettort iB dependent on the rate of acceleration, grade, car frio-
air resiatanoe, which latter is ordinarily included in fricticn.
>n la expre&aed in miles an hour per sec. 1 mile per hour per sec.
S oer sec. ISxcluding car friction, a tractive effort of 92^ lbs. per
ill produce an acceleration of 1 mile per hour per sec. on a level
the rate of acceleration will vary in direct proportion to the
ractive effort. On ordinary street cars, tractive effort during
often rises to 20O or 300 lbs. per ton.
sd or suburban roads the maximum tractive effort is generally
.per ton. For heavy freight work with slow speeds, the trao-
aonx exceeds 30 to 40 lbs. per ton.
commonly expressed in percentage of feet rise in 100 feet of
i tractive effort for a grade is the same percentage of the
drawm as the rise is oi the length of 100 feet. For mstance,
aftort tor a wreight of one ton (2000 lbs.) up a grade of 3 per
3 per cent of 2000 lbs., or 00 lbs. For the total tractive eiiort
aidded to tliis, the effort for overcoming the car, wind, and
on A level,
tiwe efforts from numerous tests are shown in the following
Tractive effort in
^ ^,^ , lbs. per ton.
r, up to 25 m. p. h 26
** " BO •* " •» ISA
«« •• 26 *• " " i ! * . ' 20
a •• •* 2B *•«»•« .'.!!!!!!!.'! 16
l^lat trmiza up to 26 m. p. h. *.'.!!'.! 6 to 10.
t
tiave to be increased for snow and ice on the track.
662 ELECTRIC RAILWAYS.
Thii eoeAelent is usually expressed as the ratio between the weight oa
the drlTing-wheels and the tractive effort, and varies largely with the oon-
dltion of the rails.
In train work, the weight on drivers shoold be six times the Imetlve
effort.
•
x»asple:— Required the weight of a locomotive to draw a lOO-ton
train up a 2 per cent grade.
For train.
100 tons X 16 lbs. for friction = 1600 lbs.
>i 4« j^40 14 u gff^^^ =4000 "
6600 lbs.
▲ssnme a 90-toii locomotive.
20 tons X 16 lbs. for friction = 800 lbs.
20 M X 40 «* " grade = 800 ••
Total tractive effort, OBOO lbs.
6000 lbs. equals IHJS per cent of 20 tons, or a tractive coeAcient of ISJi per
cent. Startmg the train on a 2 per cent grade with acceleration of | m. p. h.
923
per sec. would mean additional tractive effort equivalent to — ^— =:ao.8 lbs.
per ton.
This would add to the requirements as follows :
Train 100 tons, for friction and grade as above . . . 6600 lbs.
** " *' at ao.8 lbs. for acceleration 3060 "
Total for train 6680 lbs.
Assume 36-ton locomotive with motors on all axles.
36 tons at 16 lbs. for friction 626 lbs.
•• *• •' 40 ** " grade 1400 ••
•• •• «« aa.8 for acceleration 1076 *•
Total tractive effort . . . 11683 lbs.
or a tractive coefficient of 16.5 per cent for the 36-ton looomotiva.
Tests show the following tractive coefficients :
Sanded
per cent. per cent.
Dry rail 28 30
Thoroughly wet rail 20 26
Greasy moist rail . 16 26
With ice and snow on the track, the coefficient is lower, and the rollings
friction higher.
« •Merry. ~ Approximate capaeitv of a power station may be
assumed as about 100 watt-hours per ton mile of schedule speed for <ndinary
conditions of city and suburban service.
■xaasple t — 16-ton car, 12 miles per hour schedule,
k.w. at station = 100 x 16 X 12 = 18 k.w.
If stops are a mile or more apart, only 00 to 70 watt-hours may be neces*
sary.
Frequent stops and high schedule speeds take 120 or more watt-hours.
THAIN PERFORMANCE DIAGRAMS. 663
Th«{ollowlngt$!bleoi «8lelenole8 will b« found oonyenlant in estimating
e power raqaired for operation of motor oars, nsing three-phase trans-
'wlon and direot carrent motors. The effioiendes wonld rary somewhat
th the load factor, bat can be taken as generally applicable.
lOBfideriiy tbs I.H.P. of the engine as a basis, for the
ATerageeffloieiMy of engine Mpereent.
" " " generator 94 " "
u u 41 Blgh potential lines .... 95 *« •<
" " " substations 90 ** *<
** " " direct enrrent lines .... 92 " "
" " " motors, including losses of
control 72 " «•
Oombinsd sffloiency of the motors and series parallel
control during pmlod of cutting out the controller
msj be taken as 63 ** **
IfflelanoT ot moton after cutting out the controller,
dflptiuung on siie of motors 80to8B per eent.
rdsr to aocorately ascertain the power required to operate a given
' system ft is necessary to analyse the performance of its trains or
m'ts of transportation. Tliis is oest done by constructing train per-
M diagrams. Such diagrams may be constructed for a desired
9 and other data, in order to determine the siae and type of motor
fted to the purpose; or they may l>e made up from the characteristic
a given motor, to determine if that particular motor will fit the
toint, or just what will be the result from its use. Such diagrams
iseful in predetermining the heating effect upon the motors.
The diagram ordinarily includes:
S^eed-time curve.
Di8tanc»-time curve.
Current curve.
Voltage curve and
Power or kilowatt curve.
Is poBtihle to construct a performance diagram for a i^ven line
I diagram must be based upon the characteristics of some known
it 18 neoeeaary therefore that the schedule be stated, and
e am to heatinjc and economy be given and that motors to pro-
Mults be desijsiied by maken of such apparatus — or that motors
tandard densna be selected, which come nearest to fitting the
I €3i the case; and in determining this fitness, performance dia-
te oonatruoted from the Icnown charact^stics cl the motor
the ooiaditiona it is obvious that profile and eontour maps of
be haul in order to determine the effect of grades and curves.
tg the method of laying out these curves, the first case given
'jpon a straight ana level track and the simplest possible con-
» aeooncl example will be shown which includes grades and
A diacram o£ train performance, which shows the speed-time
-tiix&e curve, and the current curve, as well as the schedule
he diststooe between stops. This diagram is simply typical.
a typical Rsdlway Motor diaracteristic, and for simplicity
tqi veil, that of tractive-effort and of speed, the speed being
sr liour skiicl the tractive-effort in pounds draw-bar pull for
and gcectr ratio 3.09. The ampere consumption at the
snP>oou is alao given. Unless armature revolutions instead
per botir be used, it always will be neoessary to state the
\ sumI lliie acear ratio.
I
664
ELECTBIC RAILWAYS.
""
td
, 1
46
TYWCAL
RAILWAY MOTOfi
CHARACTERISTIC
88*W KEELS
PINION 88, GEARS 71.
RATIO SjO»
4S
\
\
)
90
'
V
/
■J
\
/
94
^
V .
^^
n
so
04
\
!^^
■
V
v*
^
r
r
\
^
A
^A
r
H
S4
\
^
^
/
X
y
r
so
18
^
>^
/
F
^
7^
^
^
/
ss
L
-
10
14
IS
10
^
/"
■
y
/^
/
/^
/'
B
^
tx
9
4
^
z'
^
y
L.
^
1
^
\
41
1M»
losoaoMMMioaow
UO ISO 180 no 190 SIO 180 S80
Amperec
Fio. 41.
Acceleration* — Acceleration is the time rate of velocity and is pro-
duced by the application of force. The application of a constant force will
tend to result in constant acceleration. The force of gravity will accelerate
a falling body 32.2 feet per second. The relation of acceleration to train
performance wll be shown by the following formula: Let
T — the total tractive-effort or force applied in pounds.
i «- tractive effort in pounds per ton due to train resistance.
a » acceleration in miles per hour per second, covering all train and motof
friction.
W «=» weight in tons being accelerated.
va — weight in tons being accelerated plus 10 per cent for fly-wheel effect,
« 5280 feet per mile
91.1
3600 seconds in an hour
1 . 467 X 2000
Then.
32.2
r- (91.1 aW) -{-iW
T - iW
a ■■
91.1 IF
If the fly-wheel effect be considered, then
T = (91.1 ow) +iW\
T - tW
**" 91.1u>*
1
TBALV P£RFORMANC£ DIAGRAMS. 665
CFradAh — A grade of one per cent means a oh&ngfi in altitude of one I
>( for enek 100 feet of track on the grade, and this is equivalent to a 1
ctive force of 20 pounds per ton, which will be positive, or to be added
he tractive effort per ton, if the train is going up |^de; or to be deducted
D the same if the train is on down grade. Then if (/<« grade per cent X 20
Q
formula becomei
T - (91.1 ctii>) + (t±g)W and
T - (t ±g)W
a -
91.1 w.
a —
trret. — Values of railway curves are expressed in terms of the
U angle subtended by a chord 100 feet long; thus a one deg^-ee curve
I one such that the angle at the center end of the radius will be one
; or A radius of 5730 feet, thus
de » 5730 ^
radius in feet
n'ment shows that the effect of curves is to introduce a resistance of
5 pound per ton per diM^ee of curve; thus a two degree curve will
a tractive effort of 1 . 2 pounds per ton of train to overcome the
se.
> tractive effort of a curve at d^ degrees, the formula will become
T - (91.1 olT) + (t+ c) W;
T - (t ■i-c)W
91.1 u>.
iiiAtion of a grade and a curve will make the formula:
r- (91.1 alF) + (t +e±a)W;
T - (t +c±o)W
"" 91.1V7
>f the polar planimeter will very much facilitate the eonstruction
igrams.
lod of oonstruotins the speed-time curve as described below is
ipie as can be made and was used by Mr. H. N. Latey in laying
'c o/ the Interborough Company in New York.
ee of explanation the following example of train performance
•j»Ie JU JPor VmlM V*«rfonBianc« JHarnaai.
8 motor cars, 2 trail care.
le 20 miles per hour.
2 per nule.
viiu>n a — 1.25 m.p.h. per second.
7 & "• 1.5 m.pli. per second.
r effort C » 13 pounds per ton of train.
e/ effect 10 per cent of train weight.
4 for each motor car.
vra iveigh 60,000 poimds each.
•9 -weigh 40.000 pounds each.
f train. W = 130 tons.
' effect — 13 tons
-«■ 143 tons.
( dri-oerB all motor cars « 180,(X)0 pounds.
ffort du« to weight on drivers 18 % «■ 32.400 lbs.
7* — C « X tP X91.1) +fTr.
7* = CI -25 X 143 X 91.1) + 13 X 130 = 17,974 lbs.
T per motor — 17974 + 12 = 1498 lbs.
. Fiie. 41, 1498 lbs. «> 20 miles per hour at a « 1.25.
. 1 .2^ milos p4»r hour per second is the first point p on curve.
666 ELECTRIC RAILWAYS.
Other points, jh, Ps, pa, etc., are determined by the formula,
o '^ 77r~; — • where T ia taken from the motor curve at the mOes per boor
the train is moving.
Then, let T - (IT — B. and a - - , from which the following table
may be constructed for the diagrams:
arable I.
M.P.H. r. Moion T. tW B a
7 at 20 " 1498 lbs. X 12 - 17974 - 1690 - 16284 - 1.250
" 22 - 1100 •• X 12 - 13200 - 1690 - 11610 - .840
" 24 - 840 " X 12 - 10080 - 1690 - 8390 - .644
•• 26 - 700 " X 12 - 8400 - 1690 - 6710 - .516
" 28 - 690 " X 12 - 7080 - 1690 - 6390 - .414
" 80 - 600 " X 12 - 6000 - 1690 - 4310 - .831
" 82 - 420 " X 12 - 6040 - 1690 - 3063 - .267
tw
Coasting after shutting off current •- —
or
91. Iw
13 X 130 1690
91.1X143 13027
-" — . 129 m.p.h. per second.
Table U.
Amperet per motor. Amperea per trtnn.
at 20 m.p.h. - 134 X 12 - 1608
22 '^ - 108 X 12 - 1296
24 " - 93 X 12 - 1116
26 " - 83 X 12 - 996
28 *' - 76 X 12 - 900
80 " - 68 X 12 - 816
32 " - 62 X 12 o. 744
CoaatmctlOB of Speed-Time Cnrre. — An inspeotioD of
Fig. 42 will show that the speed-time curve is divided into four parts: (a)
the acceleration due to starting the motors and bringing the train up to
the speed that will be given by cutting out all resistance, and leaving them
in multiple connection. This is shown on the diagram by oJP. (b) the
acceleration in multiple, running from P to a; (c) at which point the cur-
rent is cut off and the train lulowed to coast ifor the distance indicated
between s and n: and (d), where brakes are applied| and from n to 0 the
curve is diagonally downward, assuming that the tram retards at a regular
rate, which obviously is never the case, but is near enough so to be indi-
cated by the straijsht line as shown.
Referring to Fig. 42: The straight part of the curve, from o to p, is laid
on the drawing at an angle determined by the rate of acceleration, which in
this ease is 1.26 miles per hour per second. The example shows that at
this rate of acceleration and for the weight at train idvmi, and at a tractive
effort of thirteen pounds per ton, a total tractive effort per motor of 1408
pounds will be necessary, and by reiference to the curve 01 tractive effort in
Fig.f41, it is found that 1498 pounds correspond to a speed of twenty mlks
per hour, which becomes the first point P on the accderation curve. At
this point the resistance of the controlling devices is all out out and the
motors are in multiple from this point on, to the point t. When the current
is cut off for coasting, the speed will be accelerated at a gradually decreasing
rate as shown. The lines between the points p, pi, ps ps ^^^P* represent
the averape rate of acceleration for speeds of 22-24-20-28 and 30 mues p«
hour, and in each ease start from a point half way between the lines whieh
TBAIN PERFORMANCE DIAGRAMS.
-"^wi Sills
667
S § § 8
668 ELECTRIC RAILWAYS.
represent the ratee of speed named, the acceleration onrve o, », being
tended one-half of the speed Interval selected, or to point pi, tne other i
tions being attached to the ends.
The angle of theee lines is determined by the rate of acceleration for the
intervals shown, and in this example is based npon rates of speed Taryl^g
by intervals of two miles.
T tW
Table I has been calculated from the formula a ^ '-qT-, — • ^ being
taken from curve sheet. Fig. 41.
An examination of Table I shows that at the rate of speed of 20 m.p.h^ the
rate of acceleration is 1.25 m.p.h. per second; at the average rate of 93 m.pJi.,
or from 21 miles to 23 miles, per nooTj^he rate of acceleration is .84 ni.pJi.
per second; at 24 m.p.h., or from 23 to 25 miles per hour, the rate of aoeelera-
tion is .644 m.p.h. per second, etc., etc. In practical work intervals of one
mile each should be taken, as the curve will then be more nearly correct.
Coaatlngr. — At the point 9 current is cut oif and the train allowed to ooaat
to the point where brakes are applied and the train brought to rest at tlie
point g, 85 seconds from the starting point o. The rate of retardation, or
as it is sometimes called, deceleration a, of coasting is determined by the
tw
formula, azn— ^r-z — . or in this case, ~ .129 m.p.h. per second.
81.1 to
Sniklng'.— This line is laid on the sheet at an angle representing the
rate of 1.5 m.p.h. per second stated in the example.
Mtocatinr the Coa«tln|r JLte«. — Tne area inclosed by the
rectangle o, m, :e, y, represents the distance traveled by train in the time
shown, or a speed of twenty miles per hour, for a half mile, with a stop (tf
5 seconds duration. Therefore, the area inclosed by the speed-time carve
Of Pi *i fi> Ot must be equal to tnat of the rectangle o, m, «, y, which can be
Met determined by a polar-planimeter. The coasting line «, n Is then
adjusted up or down, always retaining the angle due to the rate of acceler-
ation, until the area inclosed by the speed-time curve is the same as that of
the rectangle. The maximum speed will then be shown by the point e. In
this case 30J( miles per hour.
]MetnBC«-Vtni« Carre. — This curve should be plotted at the
same time and in connection with the speed-time curve. Its value may be
determined for as many points as desired, but it will be sufficient for all
practical purposes if plotted for two second Intervals at the start and at the
end, as shown on Fig. 42, and at longer intervals, say 6 seconds for the
straight part of the curve. The values may be calculated at any point
along the speed-time curve and this has been done on Fig. 42, at the aame
points as were assumed for calculating the speed-time curve.
If Z) » distance from starting point in feet,
and d «• distance in feet traversed in time f, then
" -^- '•«• •'.
and JD — <f + <ft +<Ka4* <!,+ d^, etc., etc.
If the speed-time curve is very irregular it is more conrenlent to use a
polar-planimeter in getting the average rate of speed, but in cases like that
shown in Pig. 42, where the sections of the curve are drawn in straight lines,
the average rate of speed will be at the center point of each section, and
the time Interval <is the time space covered between the ends ox the
section. For instance, to locate tne first point on the distano»>time ennrs
at t, the average speed for the time interval of 10 seconds is 124S •!> 2 — 6.26,
then 6.25 X 10 X 1*467 — 01 feet and this value laid ofP on the sheet over
the time 10 seconds, and at a value of 91 feet on the scale of " distanee
feet*' shown at the right, ^ves the point I.
The average speed on the speed-time curve between 12A milee per how
and 21 miles per hour, is 16.75 miles per hour for the time interval f,
between the two points shown, of 6.5 seconds; then 16.75 X ^ X 1^467 •» JgB^
and
2> M 91, + 150 « 250, or the point I, on the distanee-tlme onrve. Agala
1
DI8TANCB-TIMB CURVE.
669
w Bnnfi tpted beCmen the next two points p and pt is 22 miles per hoar,
id the time ioterval is 2.5 BMonds, thus,
22 X2.5 X 1.407 -80andZ>-260+80- 330,
jch u (h« loeatioD of point tf.
rbe abore deMribed process u repeated to obtain each point on the curve.
)Je III hfM beta eoostnicted in this way in order to show the progressive
wal D.
rmt cafe ehookl be exerdaed in plotting both speed-time and distanoe-
) eurvei u tnoTB of loeation are cumulative, and when many points are
the error at the end msy throw the result quite out of line.
Va»le in. - Date F«r IMataAce-TlBse €«rre.
/
Total
/ •-
Time
Interval.
Total
1.407 vl
Distance
it / Averase
Time
■■
in feet
UB.j Speed u
/ Jl.P.H.
from
Distance
from
Start.
Intervals.
Starting
Point.
6.25
10
10
91
91.0
/ 16.75
6.5
16.5
159
250
22
2.5
19
80
330
/ ^
3.0
22
105
435
26
3.50
25.5
133
568
/ ^
4.75
30.25
195
763
/ 29.7
5.25
35.5
228
991
/ 30
4.5
40
197
1188
/ 29.5
5
45
215
1403
/ 28.7
5
50
210
1613
r 28
5
55
204
1817
27.5
5
60
200
2017
26.7
5
65
195
2212
26.2
3
68
113
2325
22
5
73
158
2483
14.2
5
78
103
2586
6.7
5
83
48
2634
1.5
2
85
4
2638
Cmr¥9» — From the speed curve on Fig. 41, the current,
«ed of 20 miles per hour, is found to be 134 amperes, which for
U be 2608 amperes for tne train. Point e is thus located, and
ftken with motors in multiple is twice that required for series
Ji locates point d.
per hour the curve shows that the motor will require 108
f90 tor the 12 motors, which locates point c. Table II gives
aU the pointa on the current curve, having been made up
19 on Fig. 41.
'•wmwrvmm — It is only possible to plot this curve from actual
estimating, it is common practice to assume an average
' U> mrorh out the power curve.
.■Cf Iovr»«* Cvrve. — This curve is plotted from a
(he ourrent curve and the voltage curve, the instantaneous
"yeiag multiplied to obtain the value of the power at the
r eimplicitsr neither of the last two curves are plotted here.
cilo'vrat^t ourve is ordinarily plotted by using the average
retfaer ^VFitli the current curve.
*• KK« ITliia run is of the name length as that in Example
If mile, but instead of being all straight and level traek,
*SMles stn<i curves with a portion of track which is strai^t
\ riMki^ of f*is. 43 is shown the profile and contour of the
\tStS. of csctoh change, and opposite each section will be
•ffort per ton necessary to overcome the various oondi-
ires 13 pounds per ton to overcome the train resLetance
fit trade ; grades require an additional 20 pounds per ton
ohansev and the values are shown in column g. In the
{
BLECTBIC RAILWATS.
■■•f'-i
1 - *! 'I'j-ltl
■S. !■••
■ ■> i. ..:»|.!«
.n,ni-"*f "-h::
TT ° fTwi'
~ -..Jr^-i "-I
■ "B
~ : ^ ^ : ., _ :
: ^ ~~~: :~ "
. -pZ :~
- . ± :. :
5
: ^::_ "^^ "
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::::::::!::^5:
--- s
iS
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u 2
5"
-\ , ■
s - --'•;--
' \,'
'. z 1. "^
. : T "" "
irldi SCI 1+
«»ta
1 1 1
DISTANCE-TIMB CURVE.
671
td oolamo vn shown the various effort* per ton necflasary to overcome
I ranstAnoe of the curves, at the rate of . 6 pounds per ton per decree.
t fourth ooiunm shom the combined values of all the tractive efforts
each division of the run, and in the last column are given the total
itive eft>rt for the train of 130 tons weisht.
IWble IT. — Date for 0pMi«-TlM« C«rT«, Vig. 4LB.
1 »••
.H. / Per
No.
T.
for
(W.
B.
B
1 Motor.
Motors.
Train.
- 13027
1 1408
12
17974
- 1600
16284
i.250
1 1300
II
16000
- 1600
13910
1.068
1100
••
13200
- 1600
11510
.888
1 0dO «
•<
11520
~ 1600
9830
.754
/ 870
tt
10440
- 1600
8750
.672
1 760
f
0120
- 1690
7430
.570
1 700
•«
8400
- 1600
6710
.515
/ &40
•<
7680
- 1846
5834
.448
1 690
«•
ooeo
- 1846
5114
.393
1 seo
it
6720
- 1846
4874
.375
1 *50
••
6600
- 4290
2310
.177
/MO
II
6000
- 1024
4076
.313
...
■ . •
Coast
- 1924
1924
- .148
1 540
11
6480
- 6890
- 410
- .082
• • •
...
6110
- 1690
+ 4420
+ .340
...
...
Braking
~ 1690
- 1690
- .130
- 2.05
Coast
- 1690
- 1690
- .130
1
Braking
- 1.5
1
I
y y. — M^mtm for JMaUuace-Ttaao Cvrrc, W%g. 4S.
Total
Time
from
Start.
1.467 Tf
Total
Distance
V.
1.
Distance
from
Intervals.
Starting
Point.
6.25
lO.O
10.0
91
91
16. 50
1 6.5
16.5
157
248
U.OO
1 1.5
18.0
46
294
».oo
1 2.5
20.5
84
878
15. OO
1 3.5
24.0
128
506
3. SO
1 2.26
26.25
87
503
7. SO
f 2.25
28.50
91
684
1.13
1 0.75
29.25
21
705
t.eo
1 4.65
33.90
196
900
*.70
1 1.60
85.50
69
1969
.70
6.50
41.00
238
1207
.OO
4.75
45.75
200
1407
70
7.16
52.90
300
1707
SO
7.85
60.76
340
2047
60
2.6
63.25
100
2147
70
7.0
70.25
240
2387
76
6.0
75.25
148
2527
)5
6.0
80.25
83.5
2610
'«
6.0
85.25
28.5
2638
672
ELECTRIC RAILWAYS.
The speed-time ourve on Fut. 43 is worked out in the SAtne manner a* that
on Fig. 42, except that while the speed-time curve in Fig. 42 ma^ beploCtea
without reference to the distance-time curve, in the case of Fig. 43, they
both must be plotted together, as care must be taken that the speed-time
curve is not carried beyond the point where the tractive effort, and, therefore,
the acceleration changes, as at 7, Tu T^t, etc.
Tabic VI. — G«rr«Bt ]»ata for Vig, 43.
M.F.xXt
Amps, per Motor.
Amps, for Train.
12 Motors.
20
134
' 1608
22
108
1296
24
93
1116
26
83
996
28
75
900
30
68
816
29
71
852
Tables IV and V are made up as the plotting |)rogreese8, and in the former
nve the values of a at which to lay the speed-time curve, and in the latter
snow the dbtance D and the time (i, being respectively the dietanoe and
time from the starting point o.
It reouires considerably more care to work out one of these irregular
curves for, while the method here explained is probably as short and as
simple as any, yet it requires much cut-and-try to make the sections of the
two curves fit for time and distance, and the location tff the point »j at which
current is cut off and coasting begins, rec^uires experience and judgment|
in order that the total area ex the speed-tune curve o, p, «, n, y, may equal
that of the schedule o, m, x, y.
Both the previous examples have dealt with short runs where the motors
are never left in circuit long enough to reach their speed and current Umit.
In case of long runs as on suburban lines, current is left on in full, and the
train is accelerated until the values of T "^ IW, and B is therefore sero and
there is neither acceleration or deceleration, the train moving forward at a
level rate of speed, as the tractive effort is just enough to overcome the
whole train resistance.
The values of T and tW will then only be varied by grades and carves,
and the prolongation of the acceleration curve will have to be plotted to
the point when coastinfc can begin in order to complete the time schedule.
Of course if the track is straight and level, after 7* -> <IF, the speed-time
curve will be straight and levd to the coasting point «, and the mirrent
curve also will have reached a constant value and its curve will be a straight
line until cut off for coasting.
Curves must be plotted for each run, then motors best adapted for all
purposes can be selected and the amount of power needed and the best
equipment for producing the same can be determined. After all points
have been carefully considered, due attention must be given to future needs,
and great care be taken that the equipment has not been worked up to so
fine a point that no allowances have been made for the idiossmcrasies of
the motorman who, in many cases, will entirely undo all the results of fine
calculation.
Curves like that in Example II are seldom calculated as rolling-ctock;
being operated in both directions, grades praoticall3^ neutralise each other,
so that a curve like that in Example I for strtuj^t and level traek is
quite accurate enough for all practical purposes.
BATING THE CAPACITY OP RAILWAY MOTORS. 673
MAXaQ THE CAPACnr OF lftAII.tr AY KOTORS
JPROM FBAFOlftlKAlf CS CVJBTK0.
Th0 limitiof ooodition in ntins the eafiaeity of « raUwrny motor b th«
gst developed in its use. ...
Wbeo s motor 10 carrying any load, eertain oopper and iron Io««b take
ace in it, irhioh depend upon the load. It ii these loases, whieh appear
beat, tliat tend to raise the temperature of the windings. Thua a loos of
<ee watti (oeglectiiv radiation) will raaae the temperature of one pound
1
Fig. 44.
xxmatflly 1^ C. per minute, or of one pound of iron approzt*
r xnjnute. Tbe oopper lose depends upon the current only,
luaJ to ita sauare, out the iron, or core Iom, depends upon
and tliQ volts^pe and does not follow an^ simple law. The
lotors in Question, when carrying any nven current at any
1 aiio'vni, in Figs. 44 and 46. Its dependence on both
ta^sm mAy be seen in Fig. 44, from the fact that 20
olts proauoes the same loss as 105 amperes at 305 volts.
Qsat -mAmaf of metal in its frame, a motor has a considerable
trflMce o&pcusity. Instead of only a few hundred pounds ci
.„^ to be aoted on, the temperature of the frame must
ooolins. tJ^e entire mass must oool off simultaneously*
674
ELECTRIC RAILWAYS.
Put j^ when th» t^mp«ratiir«of the windinfB is rwinc, that of the fraoM
must abo rise, and siimlarly when faUIxi]K. The actual temperattiree of the
different parts may, of course, be Widely different. Owing to this action,
the temperature of the windings of the motor does not fluctuate in aceord-
anoe with the instantaneous losses but rises at a fairly uniform rate dependhic
on their average value.
The important factor as regards the effect of the service loads on the
motors, provided that the mazmium loads are within the proper limits, it
thus the average value of the loeses, averaged, of course, over the entire
lime of the cycle. Ibis evidcDt that the averace copper loss In any oaae if
Fio. 45.
equal to that which would be produced by the continuous ap|)lieation of a
current equal in value to the root mean square oi the service currents.
ThuH, if this current and voltage b applied to the motor for the entire cyde.
the averace losses in the motors -^ both copper loss and iron lose — will
have the same value and the same distribution as the losses due to the
service loads. This voltage noay be called the '* equivalent " ventage of the
service.
This method of equating the service loads on a railway motor to aimi^
and intriligible terms was devised by Mr. N. W. Storer, of Pittsburg, anl
(tives a convenient way of expressing the service capacity of railway motors
m a usable manner*
The limiting capacity of any type of motor may be readily expressed bv
the nmnufacturer in terms of the current (root mean square) which it wiu
carry continuously at various voltages (equivalent volta^) with a safe rise
ii^ temperature. In choosing a motor for a given service, the root maaa
^
MOTOR B£BVICE CAPACITT CUBVBS.
677
{
8EBVICB CAPACrrV CURTfiB
Th¥rUsUoa Carve
fiSOVolfii
OrMiioceliBnUioo 290 Cte. per ton
Braking' ISO ^» ^t s*
DmUonof stop* iftSeo.
Coutlng 10 »«
XsTd taDgeat tnck .
?
•MM
7 M
1 I I \
III]
III 1
/ / I
^
/ / / i
^
/ / / 1
^
y
' / / 1
<^
•
/ 1 1
^
>•*
/ / 1
^
/ / / 1
-*^
/^
^
^
/ / 1
x^
*^
^
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•
/ / / J^^
^
-^
'•T
tf^
r
/ / -T^l
-
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—
-
m**^
lA^
•
^J^^'-^^
— —
•^
^
—
1 M*'
i=^=F^
—
30 40 SO eo TO 80 >S0 JOO no laO laO 140 IfiO leo 170 180 IM
CommercIU H^-IUUns of Motor
rotor C^paoiiy Curves, 60^ C. Rise. B-Friction Curve.
r
678
ELECTRIC RAILWAYS.
)
flBBVICB CAPACrtTT CITRVBB
O'SMbtioii Cturvo
5B0 Volts
< GroM Aoeeloration uo Lbt. per coa
^rakliig • uo ** . ^ <*
DOTAtion of ttOM 15 Seo.
Contlna 10 •» '
X«vd tangent track
t . 10 so W 40 60 00 70 80 90 100 110 120 180 110 UO liO UQaIBO ISO
"" Commercial H.£. Bating «f llotof
FiQ. 48. Motor Capaoity Curves, Q0° C. Rise. C-Friotioo Curve.
^
JSNERQT REQUIRED FOB ELECTRIC CARS.
679
QMAnac At ipPROxiMATxoir or
jumviBiD roift sMiBcnuio caim.
Mr. A. fir. Arautroim has dttvdopMMl a BMies of ounres, based upon th«
hieUon diaipvi), Fig. ^, from experimenta by W. J. Davis, Jr. B^ the use
i tiieM carm a quick approjcixnate determination of power required may
« made. Too curves shown in Figs. fiO, 61, and 52, are referred to curves
I, B, C, tm^KUfdy on diagrum. Fig. 49.
(
IRAIN^ FRICnOK CDBVES
A Ten or more 40 ton sars
B Two 40 ton cart
C One 40 ton car
ff '
"*^
^MM
^^
r^
/
/
/
A
/
^
;^
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i
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y
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=5
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te / 1 f
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y
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....
1 1 " / ' " /
>
/
r
/
/
^
J M 1
10
9C M 40 60
Lbs. per Ton
60
70
80
Fio. 49. Friction Curves.
— -Oiven an eig^t'car train for a scbeduleepeedof 26 miles per
the znaadmum speed and watt-hours per ton-mile, at one
!ie lx>ttom of the diagram, Fig. 49. for one stop per mile;
" this, opposite 25 miles per hour will be found a curve; follow
■cl to the left to the sero stops per mile where wiU be found the
•45 miles per hour. Again, above the one stopper mile the
cujrve of 45 miles per hour crosses, opposite 68 watt-houn
le first ooluznn.
680
ELECTRIC RAILWAYS.
170 86
8PEED AND ENERGY CURVES
A-Friction Curve
550 VoltB
OroM ftoceleration 120 Lba per Ton.
Braking 120 **
Duration of stops .16 8eo.
Coasting IQ
Lerel tangent track
it
»«
ti
BtopB per Hile
3
Fio. 60. Speed and Energy Curves. Referred to A-Friotion Curve of Fig. 49.
^
£N£BQY BEQUIRED FOR ELBCTRIC CARS. 681
(
SPEED AND ENBaRGY CURVES
B-Priction Curve
560 Volts
Grott acceleration 120 Lba. per TV>a.
Braking 120 **
Duration of stops 15 Sec.
CoMtlng 10 '*
lerel tangent track
«i
I
/
/
uv vvi
iV OtfT
iK
y
£> 351 1 '^
i
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p
4\
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1
i
.._^
cHf
pee
=
=
/ /
/ / 1
1J( 2 2JS
Stops per Mile
8
&6
nd JCnersy- Curvea. Referred to B-FrioUon Curve of Fig. 49.
882
ELECTRIC RAILWAYS.
180
170
160
160
140
130
120
05
90
86
80
76
70
66
eo
I 110 £ 55
^VOO^ 60
5 90^ 45
M 8o| 40
^ 70* 35
$
eo
60
40
80
20
10
0
30
25
20
16
10
5
0
SPEED AND ENEKGY CURVES
C-Friction Curve
550 Volts
Gross acceleration 120 Lbs per Ton.
Braking 120 "
Puration of stops 15 See.
Coasting 10 '*
Lerel tangent traek
.• 41
/
^
s
J
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f
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M
V
A
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r A
7
J
f
f
«^
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^^
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f
y
7
y
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y
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S
K$
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^
^
v„
X
x^
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k^
^^^^
V.
^
Q=n
Bu!
i=l
pei
^£
ScE
lis 2 2J(
Stops per Mile
3
8.5
Fio. C2. Speed and Energy Curves. Referred to C-Friction Curve of Fig. 49.
ENEBOT BE4DIBBO TOB SLBCTBIC CABS.
ass
Th« oootroUiag faotor in all of th«M ourves is the f riotlon tnrr%. whioh
iooludes truk, rollmg, journal and wind-f notion.
The ooQstantt assumed in calculating the above curves are thoee pertain-
iflff to averefi higiHspeed sutmrban work aa follows :
Groae aecelenting rate 120 lbs. per ton
BnMng effort (aven«e) 120 lbs. per ton
Duntionofatop 16 seconds each.
1>8ck aeeumed to be perfectly straight and level.
Jo the aboTS ourvee. due consideration is given to all the losses opourring
ring AooelenttoD with the standard series-parallel oontroUer and direct-
TBDt inOtDB.
1 1
ICar
Tnin
/
f
/
/
y
/
y
/
/ .^J
y
/
»
l_ ^
1 ^^
1
» «
css^
|CO^
JO 90
D 1
0 «
0 1
I — i
Wia, 53.-Tmin
Speed M. P. B.
Beslstanoe Curves for 1 Car Train
of tlae rotatins parts of the equipment generally amounts to
I this value is taken throughout, being perhaps a Httle htf^
nT^t^ioAB and low for the lower speeds. The speed curve or a
torse-po'vrer motor is used throughout. Tho energy curves
erhat affected by the amount of coasting done, although this
lininflr a faotor in htgh-flpeed work as it is in sIow-epeecT accel-
s. In order that the energy curves should be oonservativs,
I ^vitla only 10 seconds of coasting permitted and therefore
eds siven are nearly the maximum possible, and the energy
also praotieally the maximum possible with the maximum
Should power be shut off earlier and more ooMting be
SLBCTRIC RAILWAYS.
)
684
pennittad, the energy oonsumption would have been decreaeed and the
Bohedule speeds decreaaed eomevHiat also, especially with the more frequent
stops per mile.
An mspeotion of these three sets of curves will brine out the very crsat
effect ol the wind^riotion when using trains of one or two oars at vwy ni|di
speeds: in fact at 75 miles per hour maximum speed the operation of ainde
ear trams becomes impracticable with light 4(^ton care of standard construc-
tion* and even at 60 miles per hour is (]uestionabIe. To quote from the
curves, it requires an energy consumption of 47 watt-hours per ton-mile
for a train of eeveral can, ■• against 137 watt^houn per tonnaulefor a aiiicl*
10
Ca
rT]
aln
»
I>a1s
IB
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18
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bs
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orl
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0
1
A
9
0
8
0
4^
i>
1
0
f
0
T
0
1
10
9
0
Speed fn Miles p«r Boor
Fici. 6i.-TralnBe8i8tanoeGurveB for S Car Train
LeD8thofOBr,6l'5'
Height, 8'9K'
Blametar of wheeU 8B '
. Effective area, 96 squafFO foot.
No.ofiiiiii8^
ear operating at 75 miles i>er hour without stops; that Is, a dns^e car opera-
tion would demand 3.7 times the ener^of per ton that would be required
for the operation of a train of many similJar cars. Even a twc^car train
wlU require but 92 watt-hours per ton-mile, or only 67 per cent of the energy
required per ton for sin^e car operation. As these values are for constant*
speed running, while more or less frequent stops would obtain, a comparison
at say one stop in 4 miles would be nearer the actual results in practice.
Here a single car requires 157 watt-houre per ton-mile, a two-car train
requires 120 and a tram of several cars 70 watt-hours per ton-mile.
With one stop in 8 miles it is possible to make a schedule of 61 miles per
hour with maximum speed of 75 miles per hour, and a schedule of 28 miles
per hour with maximum speed of 30 miles per hour. U stops be increased
1
MOTOR CHARACTERISTICS. 686
thftt tb«y •venge one per mile, howvver. the achedole speed poadUe with
naxifflain ipeed d 75 aiilee per hour is dropped to 29 miles per hour, while
) 30 mileg per hour maximum speed permits of • schedule speed of 22
lee per hour. Thm while 30 miles is but 40 per cent of the higher mazi-
m speed it penntts a eehedule at one stop per tnile of 76 per oent of that
sJbJe with To miles per hour maximum speed. The fallacy of using high-
ad eqiiijMDeate for frequent stops is forcibly brought out by referring to
eneiiy eurvesin FIcb. fiO, 51. and 62. With one stop per mile it requires
wBttloun per ton-mile with 75 mile maximum speed equipment, and
30 miles msTimnm speed equipment can obtain 76 per oent of the same
duis with so expenoiture of only 28.5 per cent of the energy.
— 53 sad 54 show the oomparative values of train resistanoe as deter-
by various authorities. Following are several train reaistanca
f
ifae
fisldwin. A - 3 + ~
o
y
ioeering News, i? - 2 + —
I (45.ton car). « - 4 + .13 V + 0°^^^^ [i + .i(iv - 1))
Smith. B - 3 4- .167 V + .0025 ^ V*
MM 'n D / ^ . \ . ir Tr . 02^ + .25 -«
IfatUoux, R — (r7= + a J + .15 F + V.
tanoe in pounds per ton. b ■■ constant depending on diame-
iity in miles per hour. ter of wheels and journals (6 to 9).
section of car in square feet, g -■ constant depending on oondi-
it of train in tons. tion of track (2 to 5).
ler of can per ton. n — total number of cars in train.
lotor oharaeteristics are generally escpresaed in curve form as
» per hour for 33 inch wheel, tractive effort at the rim of a
1 and effiotenoy. The efficiency is ordinarily expressed as
•etweea the electrical input to the motcM* and the mechanical
ts armature shaft. When the losses in the gears connecting
shaft with the car axle are also deducted, the efficiency thus
I the relation between the electrical input to the motor and
the rim of the car whed. This relation is ordinarily referred
oy writh gears." The efficiency with gears is the one most
althoui^ it is best to have both given in order to eliminate
ciet«niuiuns ccear and friction losses by different methods of
o^ motnirtkoy.
tfrnriaMoB form the basis of all calculations involving maxi-
iute speeds auid are generally determined for 500 volts.
siU x«iiDr&y motor are now destined to operate at 600 volts.
optor oliskrmoteristics follow. It is not practicable to include
finotorB ehange so rapidly.
%nsitiS secki* ratio on the same class of motor the sum of the
ojeestr SLXkdL pinion must always be the same. For example,
OE^-^58— A--4 ; the sum of the number of teeth in gear
i
ELECTRIC RAILWATB.
^ ODtent Bt 71 Amp. Inpit AnutnroJ ttinu, V
u U Votot T«tnlii«li tM Fluloa
S » ^M JIM
ta^^otoi
Fio. U.
1 tnnu, Flald BpooU IM tnna
Pinion U, Omi M, Batlo 2M.
0 Hs filO(
» J» U» m MM
IIOTOB CHABACTEKISTICS. "687
Toft, j^tut nSU W *™»«»» * tarni n.ld Bpoob I fltnflHI) tuu I
I*
I
s- -I
i I i
i ^ t
SLEcnUC RAILWAYS.
DluacUr of WbMli t
i'3- i
/
!',
UorOB CHARACTERI8T1CS.
49 II.P. mbtt tt 7! tup. Itprt
Itit, tt mitr ttmliali 590
DkiHlv at car rim/ 3S'
iiMtlut J ttrt. RtM ipooa 110 J lin
flntm 17. ettf Si. ha, 4M
1
Flo. ei. G, E.-ao-A-t.
690
SLECTRIC RAILWAYS.
1
1
4
1
1
m
90
90
90
92
10
29
90
24
so
20
40
10
so
12
20
9
10
4
9
6
I
2000
1900
1900
1400
1200
1000
900
400
200
0
40 )I.P. oatpuf tt 72 imp, tapti
9oftM at motor lormfnak 500
Ofamotor of ear wtml 33'
irmafun 3 turiu. FhU opoo/t 110 S tum
Pfn/OM 19. Ooar 97. Bttlo 3J3
y
+ ^ £
«Btat U^
A^^"
*--^
ip
V^
it
y
t\
y
1- \
.7'
4 ^^
7
I s
7
r ^^
y'
t ^=-*
7
i ^^
it -*v^
it ^^
■■
i ^i
i -««^
4 ^S^
1 ^^
j^'^
9 10 20 90 40 60 60 70 90
imporm
99 100 119
Fio. 62. a. E.-80-A-3.
HirroR cHASAimmiBTics.
;'■
liitt tt MW~ brwlMdi sot
BItaittr t/ ear wM 33'
Itmtttrt 3 Aim, fkU ipotk IIOS ttf
riUta a. itar S4. fitlt ISI
20 M «
Pia.63. G.E.-80.A-*.
ELECTRIC RAILWAYS.
> H
if 3
\*iKa ae moear- earmlf>a*a SQO
Ota/neeer- oTcar- nr/too^ -33'
Armature Stoi-n^. f'ielct ^aoola 07.3tijma
fVn/on/e. Oear ?/. ftaUO *-*<
BO /e /eoo -
7Q ** MOO -
eo tz /ioo -
so lO /ooo -
so '€ eoo -
so 4 400 -
'O 2 ZOO -
a /o zo 30 fo w eo TO ooso JoouonoaoMoisotea
Fio.M. G-E^7-AorB-l.
MOTOB CHARACTBBISTICB.
tOH.I}ot)^)tjt at /OSAnux irmsut
MWi at motor termfncila SOO
Diamftigr of car- ivAea/s J-J'
f^ihnSSS.Oetre^./ft'CkiZ.Te
/o SO SO to so eoTo eo ao ioo/fO/iO'3o/4oiso'6o
Sia. 65. C.E.-87-AorB-«
694
cent per Irao. "
ELECTRIC RAILWATS.
30 32 leoQ -
TO 23 MOO -
eo M 1X10 y
so 20 I
10 M eooV
30 12 too ■
X a -Koy
C9nl Hr tru- ^ I'''- •>'>*pnt >t n Amp. Input Ain»ton 1 tunu, Fli
eaicl-£oar tiTe VolU Mmotorlannliuliloo ipooliM.t tami
«DCT elTuTt l>iuiist«r of ou wbMla U" nnloa B, oiui «t, Ki
K 23 /■WO
60 M tlOO
SO 20 lOOO
X 12 300
20 a ^00
m ^ 200
MOTOR CHARACTERISTICS.
B.F.oatpDtBtttATBp.lnpnt Amutun
'24 .^400
zz azoo
100 20 ZOOO
SO 'IB 1000
60 16 1600
70 U 1400
00 IZ 1200
ao 10 1000
ao 9 wo
so 0 600
ZO 4 400
10 2 ZOO
O C 0
FbSw at.
aoo
(ioo
4C
1000
36
300
32
eoo
28
too
24
000
20
MO
14
400
IZ
300
«
ZOO
0 « X JO 40 X c
0 00 X 100 "a
696
ELECTRIC RAILWAYS.
WESTINQH0U8E
No. 12A-25 RAILWAY MOTOR
500 VOLTS
GEAR RATIO, 1 4 TO eS WHEELS «« '
CONTINUOUS CAPACITY 21 AMPERES AT SOO VOLTS
OR 20 AMPERES AT 400 VOLTS
_2_
•
1
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Fxo. 70.
MOTOR CHARACTERISTICS.
697
' 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
^~
1
WE8T1NOHOU6E
No. 92 A RAILWAY MOTOR
500 VOLTS ,
QEAD RATIO, 1 8 TO 86 - 88 WHEBLB
COtrriNUOU« CAPACITY 80 AMPERU JfT MO VOLTS
" " 88 '< " 400 "
--
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Fio. 71.
698
ELECTRIC RAILWAYS.
1 1 1 1 1 1 1 1 1 1 M 1 1 1 1 1
WE8T1NQH0U6E
No. 101 B RAILWAY MOTOR
500 VOLTS
DEAR RATIOiUTO M-m' WHEELS
OONT1NUOUI OAPACITV'M AUDCBCa at ann vni t*
3"
9
•
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Fio. 72.
MOTOR CHARACTERISTICS.
699
(
■^
^
1 1 1 1 1 II 1 1 1 1 1 1 1 1
f
WESTtNGHOUSE
No. 92 A RAILWAY MOTOR.
500 VOLTS
eONTINUOUe capacity, M amperes at 800 VOLTS
if ii 28 << *• 400 "
£
-J.
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1
TH
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without Gears
Fig. 73.
700
ELECTRIC RAILWAYS.
r"
^^
1 1 1 1 1 1 1 1 1 1 1 1 1 1
5,
WE8TINQHOUSE
No. 98 A RAILWAY MOTOR
500 VOLTS
CONTINUOUS CAPACITY »0 AMPERES AT MO VOLTS
• • II 40 << II 4^ (•
1
4;.
t
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Fig. 74.
MOTOR CKAHACTEBI8T1CS. 701
r
702 ELECTBIC RAILWAYS.
MOTOS CHARACTERISTICS. 703
ELECTRIC BAILWAT3,
MOTOR CHARACTEBISTICS.
f
7/^20
"min f run ton in'
ALTEBNATING CURRENT SYSTEMS. 707
nc alfort or retardation b taken at 150 pounds per ton. Tha
I at 15 Moonds eaoh, except in the ease of the 15 miles per
m, where the stop is taken as 10 seoonds.
SBS fisores are for cases of approximately level and approzi-
Mfit roads.
Mole of 40 miles per hour the speed attained will be between 00
» per hour. A schedule of 25 miles will require speeds of from
4bb per hour, etc.
4 aeoelaration for the long runs varies from 75 to 110 pounds per
"% high as 210 pounds per ton for short runs.
«in^ applies to single car units. If units of more than one oar
« fnotion in pounds per ton will decrease and with it will also
coasumption in watt houn per ton mile.
i^Msm-nLABM AMsTmmMJL'm€^ ciiRiuBiri*
r of the aingie-phase commutator tsrpe motor for eleotric traction
ftiooBiy advocated by the Westinshouse Electric A Manufacturing
^mod a deeeriptiaii of a single-pnase systen^ proposed by that
=^ wm the Waehington, Baltimore A Annapolis Kaflwav was read by
^ g^w»w»^ before the American Institute of Electrical Engineers in
4K2. The development of this type of motor was at once taken
— manufaetoren mduding the General Eleotric Companv in th«i
a number of prcMninent companies in Europe. Toe first rail-
r the ayst«n on a large commercial scale was the Indianapolis
raction Gompany which began operation over a short portion
on Deoember 30, 1904.
an manufaeturers employ a laminated field, an armature wind-
^jeneral to that used in direot^surrent machines, and an auxiliary
Ling winding on the fidd, to neutralise the armature reaction.
also* the ain^a-phase motors <rf idl manufacturers are designed
on 250 volts or less.
_ of twenty-five cycles has been used exdusively in this country.
however, some roads employ this frequency, some lower and
frequencies. Lower frequendes are now being advocated in
»tor8 up to 260 horse-power have been built. Those in service
It time ranfs from 40 to 150 horse-power and are used in both
^ )i(^ equipments.
sntial advantages of the sini^phase system is the economy
which is secured, due to the use of a high trolley voltage.
the ventage the grsater the saving thus effected. On the other
greater the troll«y voltage the greater the difficulty of insulating
v«dta«es of 3300. 6000, 11,000 and as high as 13,000 are in use.
I have been made to standardise trolley voltages at present, but
ieiideoey seems to be toward the use of 6600 volts for ordinary
and off 11,000 volts for the electrification of existing steam
Vhmae eooipments in general indude, in addition to the motors, a
deafened troUey to ooUeet the high-voltage current, a transformer
the voltage for use at the motors, and the necessary controlling
» regulate the supply of the current and control the speed of
Thcoe latter devices consist of dnim-tjrpe controllers for small
its and sin^ ear operation and unit switches operated by inde-
power for large equipments, or where multiple unit service is
•phase alternating current motor will operate equally well on
It of the proper voltage and by connecting two or more motors
a ain^e^phaae ear equipment can be arranged to run from an
direet-eurrent trolley as well as from a high voltase single-phase
Witii mnA an arrangement, cars can be run over the same tracks
oity can when entering a town.
r
708 ELECTRIC RAILWATS.
ALTEBNATINQ CURBENT SYSTRUB.
709
inipmiint for multiple
t. Id thig equipment
lie* opeiBted by oom-
u those wopli^'ed in
dirMt-current moton.
inet valvee opented
nie ftuidliuy dreuiti
the uaiwl my » that
tee the main iwiteiua
I.
knd the main eiritcbei
ped with lour 50 hone-
ndnipla ecmipment at
by the Oenetml Eiectrie
. and fipre 86 etiom
ourrent.
I lingle-phAM moton
rtrio Oompania.
710
ELECTRIC RAILWAYS.
Fio. 82, Diasram of Appwatus for Unit Switoh Syston of Multvit
A. C. EquipiiMDt.
Fio. 83. Diasram of Apparatus for Hand Oontrol, A. G. EqaipoaBBi
««n«r»l Blectric Companj*a "BLmmd P»teMtl»l CTMilMi
Uymfwm.
Thifl being a Bystem of hand control for alternating current ninaii
it IB lesB oomplioated and somewhat lifldnter than a train Bystem. T1ie< ^
Electric potential oontrol is also used for combined alternating eumwj
direct current running by the addition of starting resistances and a '
tating switch, whose office is to make the neeessaipr change in —
This potential control gives a higher efficiency equipi
by any form of resistance control.
equipment than Si
ALTEBNATINQ CDBSSNT SXBTElfS.
R
r
712 BLBCTTBIC RAILWAYS.
SINGLE- PHASE MOTOR CHARACTERISTICS.
aA»M M*TOB CnABACTBBISTKca.
ma* u« ■ numbo' of Durveo ■bowing the chuia
r
rfUiudiH^
-
-
-
QBHERAL ELEOTRIO
OOMPEH8ATCO A. 0. MOTOR
T6M.P. 200ValU
83*WhHl asOvsIn
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704 BLECTBIC RAILWAYS.
MOTOR CHARACTSaiSnCS, 705
i
706
ELECTRIC BAILWATS.
1000
P XK
X
X
60
1000
P XK
T
00
1000
T
Qotahall gives the foUowins aa a method of approximating the demaad
lor energy of an eleotrio railway.
Let
W — maximum wei^t of loaded oar* or train uniti in tons of 2,000 pounds «ad&-
D i" length of rocuT
T —time in minutes occupied in running between termini •- single trip.
K -■ enero^ consumption in watt hours per ton mile.
N — numoer of can or train units on the road during time of mmwiw^^nw
service of minimum headway.
Then.
TF X X> - ton mile per trip - P.
P X K
"■ energy per trip in kilowatt hours.
"■ mean rate of energy input per car or train unit.
X AT " A "■ total maximum average energy required at ths
oar motors for maximum service condition.
If to the foregoing, 25 per cent be added for transmission losses and hast
and light,
eOxPXKXNX 100 ^ ^^PXKXN . j j »
— 1000 X r X 75 " f ■* "**"'""'" average demaDd-£.
To R must be added the fluctuations, which will vary from .2R to .33 JI.
as the number of train units in regular service are great and the average load
consequently relatively high, or as the number of train unite in rfM{uIar esr-
vice are few and far apart, and the consequent relative increase or the load
during certain hours relatively neat.
In the foregoing, the quantity & is the important quantity. K will vary
with the schedule and tne location, the distance between, and number at
stops and stations, as well as with the alignment and gradients. Table VIL
has been compiled from data showing relations between schedule speed
and energy consumption in watt hours per ton mile. These figures are
based upon approximately straight and level roads. As the effect of grades
upon ener^ consumption is, to a large extent, compensating, the data may
be used with safety. The compensating effect above referred to is due to
the fact that while a oar 'going up-grade is consuming more energy, per
contra a car going down-grade consumes much less or none, thereby eqwtl-
ising the effect of, or compensating for, the gradients.
Table VU.
Watt Hours per Ton Mile for Schedule Speeds of
Distance between
Stops.
40 miles
35 miles
30 miles
25 miles
20 miles
15 miles
perhr.
per hr.
perhr.
perhr.
perhr.
perhr.
Miles.
Feet.
3
15.840
110
80
78
65
53
40
2i
13,200
121
90
83
74
54
40
2
10.560
142
99
86
80
60
41
u
7,920
123
95
85
68
43
1
5,280
128
90
74
50
1
2.640
145
119
56
1.320
120
Train friction in
pounds per ton
35
30
27.5
25
20
15
be used, the f notion in pounds per ton will deercMe and with it will abo
deeneM the enecgy oonsumpUon in wntt houn per ton mile.
Tlie UM of the eini^e-phAae eommutator type motor for electric traotion
- first seriovnly advooated by the Westinghouee Eleotiio A Manufaoturing
Gbmpany, and a deseription of a Binc^e^phase systeiXL jpropoeed by that
company for the Washington, Baltimore 4c Annapolis Kauwav was read by
Mr. B. G. Lamme before the American Institute of EUeotrical Engineers in
October, 1902. The development of this type of motor was at once taken
op by other manufaoturers mduding the General Electric Company in this
ooontry and a number of prominent companies in Europe. The first rail-
way to employ the system on a laige conmiercial scale was the Indianapolis
A (^einnati Traction Company, whioh began operation over a short portion
of iU track on December 30, 1904.
Practically all manufaoturen employ a laminated fidd, an armature wind-
ing similar in general to that used in direct-current machines, and an auxiliary
or compensating winding on the field, to neutralise the armature reaction.
In general, also, the single>phase motors oi all manufacturers are designed
for opefataon on 250 volts or lees.
A frequency of twenty-five cycles has been used exclusively in this country.
In Europe, however, some roads employ this frequency, some lower and
eome higher frequencies. Lower frequencies are now being advocated in
the United States.
Siaes of motors up to 250 horse-power have been built. Those in service
at the present time range from 40 to 150 horse-power and are used in both
two and four-motor eqmpments.
One of the essential advantages of the single-phase system is the economy
if feeder copper which is secund, due to the use of a hi|^ trolley voltage.
rhe hi|dier the voltage the greater the saving thus eifectwi. On the other
Mtnd. toe greater the trolley voltage the greater the difficulty of insulating
he line.
TioIl«y Toltages of 3300. 6600. 11,000 and as high as 13,000 are in use.
fo Aitempte have been made to standardise trolley voltages at present, but
he genenl tendency seems to be toward the use of 6600 volts for ordinary
noUey rornds and of 11,000 volts for the electrification of existing steam
ulwftvs.
Since-phase equipments in general include, in addition to the motors, a
leeially designed trolley to collect the high-voltage current, a transformer
» reduce the voltage for use at the motors, and the necessary controlling
rvioea to regulate the supply of the current and control the speed of
e ear. These latter devices consist of drum-type controllers for small
utpments and single car operation and unit switches operated by inde-
naent power for large equipments, or where multiple unit service is
sired.
Fhe aincie-phase alternating current motor will operate equally well on
ae^ current of the proper voltage and by connecting two or more motors
mmwimm a sini^e-phase car equipment can be arranged to run from an
lixaskry direct-current trolley as well as from a high voltage single-phase
Uey. With sneh an arrangement, cars can be run over the same tiaeka
oraiiisbry eity can when entering a town.
(
ALTERNATING CURRENT SYSTEMS. 707
The bnaldng effort or retardation is taken at 150 pounds per ton. The
•tops ars taken at 15 seconds eadi. except in the ease of the 15 miles per
hour ichedttle, where the stop is taken as 10 seconds.
The foregoing figures are for cases of approximately level and approxi-
matdy strai^t roads.
For a sebedule of 40 miles per hour the speed attained will be between 60
end 65 mQes per hour. A wmedule of 25 miles will require speeds of from
40 to 50 miles per hour, etc.
The rate of aooelwation for the long runs varies from 75 to 110 pounds per i
ton, going as high as 210 pounds per ton for short runs. I
The forsgoing applies to single car units. If units of more than one ear 1
hfl tHMr). thA fnniinn in tmunHa fwtp trun ^11 At^rmmam And writh it vrill alaa ^
SLECTRIC RAILWATS.
WntingbouH Eisotiio A Uaoirfutiiridi Compaay.
the dlasram that tb
of Thlcb the motoi
former « ■
■pes^ tha pover [aquljeii ii laduosd In *i>pnHElm^ pn^nntan t
ALTBRNATINO CURBBNT STSTEM8.
709
Ficim 81 rimm a sebemAtio diacmn of a oar equipineiit for multiple
onit ofmtion on either direct or altematins current. In this equipment
the main drouits are opened or oloeed by unit switches operated oy com-
pressed air from the brake system in the same way as those employed in
the Westingfaouse unit switcn system of control for direct-current motors.
The main switches are controUed by means of maoiiet valves operated
throu^ auxiliu7 drouits from a master switch. The auxiliary circuits
are carried from car to car by flexible connections in the usual way so that
the operation of the master switch on any car operates the main switches
on allmotor cars simultaneously. See Figs. 81 and 82.
TIm auxiliary drouits between the master switch and the main switches
(
OhndtBkr.
^.C.TroUfly D.G.TroUey
/
MSracf Switeb
PoHBwItcbw
i^ Ss S* ^8
L.A. ^ lft« b
^1~\ I BaterMf <
X flaqtwnce of 8wi«cb«s
a
I.
U^IBBCIBaS-> ■
BJifSgLSS^dT
OBwwlns MotchM
Fxo. 81. Sehematie Diagram of Westinshouse A. G.^D.C. Gar Equipment.
^^^ led through an automatic change-over switch, which normally remains
in the poaition for direct-current operation but which changes to the position
for alternating-current operation whenever alternating current is suppned
to the oar transformer. By this armngement operating the same master
scmtioUer doses different main switches, according to whether dirset current
>r altematins current is bdnc used by the car.
For the sake of deamess the auxiliary circmts are not shown on ttiis
*- igure 83 shows a schematic diagram of a car equipped with four 60 horse-
x>vrer sinRle^phase motors for operation on 3300 volts.
Fisure 84 shows diagram of connections for a quadruple equioment of
'5 horae-power motors with hand control, as supplied by the General Electric
V>inpekny for operation on alternating current onlv, and figuw 86 shows
iasrazn of connections for the same equipment with multiple unit control
yr operation on both alternating current and direct current.
Fisnire 86 shows performance curves of typical single-phase motors
uuiafaotund by the Westin^ouse and General Eleotno Umipames.
710
ELECTRIC RAILWAYS.
Fig. 82. Diagram of Apparatus for Unit Switoh System ai Multiple OoiUro^
A. C. Equipmeot.
■■MMMOTiiVi
7>»//#K
iCcif^wur
hMr//tCyMw
Fig. 83. Diagram of Apparatus for Hand Control, A. C. Equipment.
C^enorwl Slectric Companj'a HiiMd Potential Control
filyatOMi.
This being a system of hand control for alternating current running only,
it is less complicated and somewhat lighter than a train system. The Geoeiml
Electric potential control is also used for combined alternating current and
direct current running b^ the addition of starting resistances and a oonunu-
tating switch, whose office is to make the necessaiy change in eonnection.
This potential control gives a hiefaer efficiency equipment than is i»OTided
by any fonn of resistance control.
ALTSKNATING CDBSBNT SXSTBHS.
Id
m
14
1
BLBCTBtC RAILWAYa.
^
SINGLE-PHASE MOTOR CHARACTERISTICS. 713
Following are a number of ourvee showing the characterifltios ol the
General Electric and WeBtingbouse single-phaee railway moton of this date,
November, 1906.
^
nBMVDAi B-t Btvratn
0QMPEN8ATCO A. O. MOTOR
76 H. P. 200 Volte
88' Wheel 26 0volea
A« 0, Oharaotertatioa
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PI
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14
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18
10
A
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Fio. 80.
714
ELECTRIC BAILWATS.
ncMacDAi CI Kn^oifs
g
OOMPEN8ATED A. 0. MOTOR
76 H. P. 160 Volts
33' Wh*el
D. O. Oharactertstlcs
1
m
'X
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— 1
0
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Fia. 87.
SWaiiB-PHASB MOTOB CHABACTEBISTICS.
715
400
Ampwwii
Fio. 88.
r
716
ELECTBIC BAILWAYS.
s
IBO
180 80 40
140 70
120 80
100 60
80 40 SO
80 80
40 90 10
SO 10
4188 RAILWAr IfiOTOR
IfiO VoltA Direct Ciurent
86'WheeJ8 Gear Batio SQtaS
Performance of WeedogbooM
UO.H.P« Single Pliaae Motor '
operating four in terlea oa
800 volts direct cotrent.
I
i
sooo
400
Anipei^
Fig. 88.
^
BINQLE-PHABB MOTOB CHABACTEBI8TICS.
717
i
I
I
100 600
1
I
8
o
m
•0 100
10
10
40 too
10
•f lao aAlCWAY MOtOB
0Oyolt»— SOQOAltt.
BliifflePhftse
tt*W1iecfl»
PwfOcniAaca o^ao fl.r.
IVMtiiighoiue gewlaci
Single PhMe Motor for
Sbvt Yonc, Hew HaTon
* HMttdrd BalltoiA.
tooo
i
{
0 too 400 ooo
£
1000 uoo laoo lioo imo
Fio. 90.
r
)
)
718 ELECrSIC RAILWAYS.
HIGH SPEED TRIALS. 719
Wdf hte •€ Altenmtli^rwCi
The aJtenuitiQg'KmiTent motors are somewhat heavier than dueot-ourrent
moton of equal capacity.
C«aipai«ttTe fTelrliti tS Hone-Power, Waur Motor
Sqolpment,
Direct Ctirrent. Alternating Current.
Ckrbody 22.000 lbs. 22,000 lbs.
Trueka 14,000 lbs. 14.000 lbs.
Motore 15.000 lbs. 20.000 lbs.
Tiansformera and control 6.000 lbs. 8,000 lbs.
Total 57.000 Ibe. 64.000 lbs.
A C
Increased weight ^^ — 12.3 per cent for total equipped car.
OnCfH SPUBD TMMJLMM Olf XiAKS SIiSCTUliC
The motor equipment of car No. 18 with which the records were made
comprises four G. £. No. 66 125 horse-power motors, and G. E. type G
controller, connected up for train control. A q>eed of 65 miles per nour
was attained at a pressure of 575 volts. The car requires between 400
and 600 amperes during acceleration, and 260 amperes at full running
speed. It is veetibuled at both ends, seats 56, and is 49' 6' long by 8' 6*
wide, webbing, loaded, 36 tons.
On a nii^t run from Fremont to Toledo and return, with a loaded car
weighinfic 36 tons and with a dear track, the distance of 33.16 miles was
ooivered in 1 hour. 11 minutes and 10 seconds on the down trip and 1 hour
and 10 seconds on the back trip, an average of 34.3 miles per hour on
the down trip and 35.3 miles per hour <» return trip. From Fremont to
the Toledo city limits, 30.42 miles, the time was 52 ndnutes and 10
seconds, and on the return trip 44 minutes and 30 seconds, the former
to average of 41.2 miles, and the latter an average of 41.85 miles per
iioiir. It will be noticed from the accompanying table marked "theater
•un/* that when the car was making its highest speed the watts per ton
nile "were practically equal to the speed in miles per hour. The current
oosumption within the city limits of Toledo where city cars were in
operation, and where there were many bad curves, was about three times
m gnreat aa on a straight level track and with less than one-fifth the speed.
lie incrooso of current consumption caused by grades and curves is also
(
(
720
ELECTRIC RAILWAYS.
)
I
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J3
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• •••••••■•••••••••••a
h»h-r>-r^h»1^00000»0»0»0«0»00000t^
MNdWC^NCOCOCOCOCO
eowpoeoN
mOH SPSBD TRIAIiS.
1
721
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OO^iO<-iCIC4'HiO«4ioOCOCOOQ
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^;5^oot;3cgr^oo^«gg5cj|
722
ELECTRIC RAILWAYS.
By W. E. Ooldsborougfa and P. E. FaoBler. Trant. A. I. B. B.
Tests Madb upon Cabs of thb Union Tbachom Gompamt op Indzaxa.
The cars used measure 52 feet 6 inches over all and weigh 63.100 pounds.
The motiTe power equipment consKSts of two number 50 G Westanshouse
motors, which are mounted on the forward truck and are nominally rated
at 150 horse-power each. The motors are geared with the ratio of 20 to
51 and are geared to 36-inoh wheels. Records were obtained from 10
oars of this t^pe.
The following tables give the results for several different cars used oa
various routes, a special test of three cars, and a table showing the pereooal
factor of different motormen:
TrrfnNo.
Gar No.
Direction.
K.W.n.
Per Ckr Kile.
1
12
19
28
35
246
246
246
246
246
East
West
East
West
East
131.2
128.5
125.6
134.8
119
2.32
2.28
2.21
2.38
2.11
2.21
Average. West
2.33
9L
18L
25L
34L
250
250
250
250
East
West
East
West
107.4
123.8
108.5
119.6
1.9
2.19
1.92
2.11
Aversce. East .
1.91
Aversge. West
2,15
39
32
44
252
252
252
East
West
West
128.7
139.5
113.1
2.27
2.46
2.00
Average, East
2.27
Aversge. West
2.23
6
13
22
29
41
42
254
254
264
254
254
254
West
East
West
East
East
West
142.5
137.6
189.2
162
119.0
126
2.52
2.43
2.46
2.86
2.10
2.23
Averagf^, East .
2.46
Average, Weat
2.40
^
INTERURBAN CAR TESTS.
'• -* ^OAlKIMtd*
723
nainKo.
GbtfNo.
Direction.
K.W.H.
K.W.H.
Par Car Bfile.
lOL
17L
26L
33L
255
255
255
255
Weit
Eaet
Weet
East
101.0
96.0
106.0
101.0
1.77
1.70
1.87
1.78
AvnraM, KtJHt .
1.74
Arense. West
1.83
2
7
15
16
23
38
260
260
260
260
260
260
West
EMt
East
Weit
Eaat
West
122.4
130.6
127.6
114.2
133.5
128.5
2.16
2.30
2.25
1.85
2.35
2.27
Aviing9, Rftst . .
2.30
Averacei Weit
2.09
31
8
24
261
261
261
Eaat
West
Weat
156.5
142.0
132.8
2.59
2.51
2.34
Armun. Tkurt . .
2.59
ATeraseb Weft
2.42
30
3
14
21
37
262
262
262
262
262
Weat
Eaat
Weat
Eaat
Eaat
127.0
111.0
122.0
123.0
112.5
2.24
1.96
2.15
2.17
1.98
A.verure. £aat .
1
2.03
Ikverace. West
2.19
11
20
27
40
43
4
263
263
263
263
263
263
1
East
Weat
Eaat
Weat
Eaat
Weat
124.5
135.5
94.5
134.0
118.5
140.0
2.20
2.39
2.48
2.37
2.09
2.48
-vMr^f «. FiMt .
2.20
V^TMPM iXraMft
2.41
{
724
BLBCTRIC RAILWAYS.
VmMOm
of Oav
I
Number of
Serviee, weft bound
Weight
Gear ratio*
Total time trip, min
Time urban work, min.
Time interurban work, min. . .
Ayerage apeed for trip, m.p.li. .
Average urban 4>eed, m.p.n. . .
Average interurban apeed, m.p.h.
Total aUrta
Urban atarta
Interurban atarta
Maximum apeed, m.p.h. ....
Running apeeda
Ruimiiig ourrenta
Train reaiatanoe oorraaponding
Iba. per ton
Time to reach 25 m.p.h
Acceleration current, max. aeriea
Acceleration current, max. par .
Conaumption, k.w.h., p.cm., weat
Conaumption. k.w.h.. p.cm., eaat
Conaumption, watt-hour per ton
mile, weat
Conaumption, watt-hour per ton
mile, eaat
8q. root mean aq. ourrent, weat .
8q. root mean aq. current, eaat .
Running factora, weat
Running factora, eaat
Average voltage, weat
Total conaumption k.w.h., weat .
Total conaun^tion k.w.h., eaat .
255
i-limited
63.100
23:48
122
44
78
28
8
39
18
5
13
64
50-^
173
27.7
30
280^40
320^640
2.20
2.38
69.7
75.5
95.6
105.5
43.5
43.3
485
124.9
134.3
252
k>cal
63.100
20:51
156
40
116
22
9
26
44
15
29
52
40^*5
145
19.9
30
200-300
250-300
2.44
2.80
77.5
89.0
92.1
98.4
87.8
31.5
429
138.0
176.2
252
limited
63.100
20:51
126
84
92
27
10
33
12
7
6
« ■ B • a
40-46
145
10.9
30
200-800
250-300
2.10
2.32
66.7
73.5
78J)
87.2
36.2
37.6
• ■ • • ■
118J
131.2
Viable JLKJL
mml Factor of Moto
Eaat.
•
Weat.
Tripe.
Total K.W.H.
Total K.W.H.
Namb.
Min.
Average
Max.
Min.
Avenge
Max.
East
Weat
Eller
122
135
148
114
125
136
6
6
Lee . .
116
121
126
124
129
130
4
4
Robbina
122
131
138
119
124
128
4
4
Qreen
113
123
131
126
134
141
3
3
Young . .
118
122
128
112
128
145
3
6
Griffin . .
124
130
140
127
131
134
3
4
Embry . .
108
126
154
134
135
135
3
2
127
130
26
29
1
INTEKtmBAN CAB TE8T8.
725
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RAILWAY MOTOBS, STANDARD SIZES AND RATINGS. 729
Tr8T bt United Railways and Electric Compant or BAi/mfosB.
Reported bt H. H. Adams.
Gab Na 710. — 31-foot body; double tracks; 33-inch wheels: weight,
45.000 jMunds empty; seats 44 paseeiicers; 4 Westinghouse 101 S motors;
gear ratio 1:3.66.
Cab No. 730. — 31 foot body; maximmn traction truck; 33-inoh driving
wheels; weight, 31,700 pounds empty; aeats 46 paneogers; 2 Westinghouse
56 motors; gesr ratio. 1 :3.56.
Test.
Horsepower . . .
Gear ratio ....
Average kw. . . .
Average anmeree
(asmiming 500 v.)
K. W.H. per ear mile
(V^att-hours per ton
mile
iverage number
paseeng«s carried
per round trip .
Car No. 710.
160
18:66
28.47
56.05
3.525
155.5
145
Relative
per cent.
100
100
100
100
100
100
100
Car No. 730.
110
18:64
25.65
60.6
3.17
200
148
ReUitive
per cent.
68.7
07
00
00
90
128
102
i
{
laflway Motors, ftteMdAvd Mses »■# liatfaeg^, Ifor. 194HI.
Type.
Make
Rating.
Weight.
12A
49
Westing
ouse 30 H.P.
35 "
2200 lbs.
1920 ••
92
M
35 ••
2265 ••
68
•t
40 "
2280 ••
101
•t
40 ••
2730 "
38B
•«
45 "
2390 •*
56
Ct
50 "
3000 "
93
#•
60 "
3350 "
112
• •
65 "
3490 ••
76
M
75 "
3840 "
121
««
90 "
4300 "
119
«t
125 "
4600 ••
60F
• «
150 "
5560 "
114
• «
160 ••
5300 "
86
««
200 •'
6600 "
113
1*
200 ••
6550 "
Weight including Gear
and Gear Case.
.£. 800
Gcoi. EU
sc. 25 H.P.
1800 lbs.
52
25 "
1725 "
•• 1000
36 "
2180 "
67
40 ••
2385 "
70
40 "
2530 "
SO
40 ••
2530 ••
67
50 "
2972 "
74
65 "
3534 "
73
75 "
4022 "
66
•• •
126 "
4378 '•
66
160 "
5416 •'
09
200 "
6100 ••
1
730
BLBCTBIC BAILWAYS.
I
Type of Motor.
HotoiB.
Cootrol.
WciKht.
G.E. 800
2
KIO
4.750 Iba.
•* 800
4
K 6-
8,740 -
- 52
2
KIO
4«390 **
•• 62
4
K12
8,100 "
- 1000
2
KIO
5310 -
- 1000
4
K 6
10.290 -
- 67
2
KIO
5.710 "
" 67
4
K 6
11.090 "
- 67
2
Kll
6.994 -
- 57
4
KU
14,108 "
- 74
2
TndnTypeM
•^925 Z
- 74
4
M
16.586 "
- 73
2
••
llj0*4 -
- 73
4
M
20.768 -
- 66
2
M
13.230 -
- 66
4
••
23.760 -*
- 65
2
M
13.680 "-
•• 55
4
M
26.640 **
- 09
2
M
13,600 -
69
4
M
26.600 -
W— liyhotiwl2A
!
KIO
K12
5.400 *-
10.100 "
49
2
KIO
4J900 -
49
4
K12
9300 -
92A
2
KIO
5.570 -
92A
4
K28
10.500 -
68
2
KIO
5.T0O -
68
4
K 6
10.700 -
lOlB
2
KIO
6.600 -
lOlB
4
K28
12.500 -
38B
2
Kll
5J»0 "
38B
4
K14
12.150 *
lOlD
2
Kll
6.600 -
101 D
4
K28
12.500 -
56
2
Kll
7.200 -
56
4
K14
14.600 **
93A
2
, Kll
7310 -
93A
4
' K14
14.700 -
76
2
K 6
9.450 -
76
4
L 4
19.000 -
112
2
K28
8.000 -
112
4
1 ^ ^
15.750 -
93A
4
Unh Switch
15445 -
112
4
M
16,205 *
121
2
••
103T0 -
121
4
*"
19.485 -
119
2
M
11.495 ~
119
4
••
21.100 -
114
2
••
12.915 -
114
4
••
M.455 *-
113
2
••
15.785 -
113
4
29w535 *
COPPER WIRE FUSES FOR RAILWAY CIRCUITS. 731
iffoni^ini Aim HonsiB-powvm.
^
H.P. per Lb. Applied at Periphery at 100 Rev. per Min.
Diameter
Wheel
26'
23'
30'
33'
36'
H.P.
.02062
.02221
.0238
.02618
.0^2856
Pounds at Periphery per H.P. at 100 Rev. per Min.
Diameter
Wheel.
26'
28'
30^
33'
36'
Lbe.
48.481
45.018
42.017
38.197
35.014
i
{
Lbe.
126050.9 X H.P.
Diam. X Rev.
H.P. — .00000793 X diam. wheel X rev. X lbs. at periphery*
EI.P. per lb. at peripherv at one mile per hour » .002667.
Lba. at periphery per H.P. at one mile per hour » 374.9.
If •#• OB BBteiv«Bcy BrvakiBC of Cars.
n ease of emergency, motormen often reverse the motors, which brings
ear up with a severe jerk, and is quite apt to strip gears. This Is
necessary, and should never be done unless the canopy switch is first
>wn off. then when the motors are reversed and the controller handle
>wn around to parallel, the motors will act as generators and will briim
car to an easy stop with no harm to the apparatus. In case circuit
Lkers are used m place of the plain canopy switches, the reversal of the
ors will draw so much current from the line that the circuit breakers,
roperly adjusted, will open the circuit and the controller can then be
[ as susgested abov&
IPTUB rVBMB rOR R JJEIiWAY OXliClIITA.
AS.
uses.
17
16
15
14
13
•
12
11
10
9
390
8
450
7
» Point
in
l>or<eo»
100
120
140
166
200
235
280
335
520
732
5
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ELECTRIC RAILWAYS.
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APPROXIMATE DIMENSIONS OF ELECTRIC CARS. 733
i i
8 S 8 S 91
?* ?« 'i ^ ^
|l |t |l i §
* * ^ i s
II
Sis
^ 1
1
tationary baek
8 reversible
2 stationary
13 reversible
2 stationary
seats each side
of aisle
1
s;
•
^ —,
^ j_
•
•
s
S S ¥
) S3
t»
■
•
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•
■
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•
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•
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ft
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1
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1
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t
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1
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c
1 c
5
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ft
9%
|l
1
11
i
i
DIUEN8I0NS AND WEIOBTS OF CABS AND TBUCKB. 735
ifaiiiijiiill
Mi SSSSS S SS8S S IS§8S3
3 **
e
i ' , . , I
3 J«='S = S2= = 2sas 2 52 = 822
II
1
■*. |. ^ . ■ -s' 1 J-iJ
rl'i . li;; ; iiJj
ELECTEIC RAILWAYS.
!
1
if:
u
ii
i;
1:1
1
•s
1
I:
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1. 1
8 8
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55
Hi
■lb t !. h
;SS S = g
11
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iii^g sis
1
u
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Mill!.
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nil:
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DIUENSION5 AND WEIQHTS OF BRILL CARS. 737
li:
1
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ill li II
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ElifeCTRIC RAILWAYS.
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BLBCTRIC LOCOUOTt^^
Tb* nnmber of alflotilfl IcHmnotlTH in flommfralBl op^rmtloD 1* rmpidly
burcadiic. Tha aarviea m](«a fnMn ysrd ■hiltinc, for whiah they mn
IBTtinibuiy ml] adiipWd. up to the tuuIitiK of puBouin truni of BOO ton*
■t to BtOm per hour. The motor cspedly vuiee from two 50 hone-po<rer
moton of tb* £Mr«d type up to the four 650 hone-poirer geailMa moton
00 the "UotiA" type of the Ne* York Ccntrml looomottra.
The foUowinf Ikt i* of intersit: ISOT.
Oendntla . . .
9£t«i BftlUmore
Hoboken' K.R. '.
BuSido dt U»kport .
Puie i Oi-1esn* .
ConpAfikie FrAncmL
TboauDO-Hounon 1
it. Louie ± Belleville 1
3. a Co. 30-Too
Yud Looomotlve
afVTcHi Baltimore *
lueh Tarmiwl Ca .
I. E. Co. 40-Ton
Y»«l Loeomotdve,
.T. C. 4 H. H. R.R.
O. E.CO. . . .
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p- Hoton in multiple
II Operate* >ba on IIMO TOlM. A. a
Jo Btaadard eleotHo locomotive deeicn ba« been re&ohed. iJtbouch m&Djr
>mfiCiv«a fltjuipped with seftred moton have the geneiAl Bhape ehowD
Fw. 92 (G. E. Co.). The moton, four b aumbar. kre feered to the
Lt u^t wt^l ''i5r"T'Si i^n™™«.ntSi.'^e Pontrolkir. 'end^tS
itArtin^ Tseutanoei. While thie design
le latftr lowmoUvee ue^iuL
^ _ .ype havitig m. lolid ctut-iteel
the letei B. ± O. locomativee tn
ii twccie truiilu ii luitible fai
>t«d to withstwid the etnini „
h], baiHiik there hae beaa developed
740
ELECTRIC RAILWAYS.
G.C.CQ.
No:4
. o "^ o ji
Fio. 92. Typical Eleotrio Locomotive of Q. E. Go.
typieaL A ctom cection is shown in Fis. 03 of a half unit of the B. & O.
locomotive. This locomotive has a rigid wheel base and contains foar
geared motors of a total capacity of 1600 horse-power. It is well adapted
to stand the shocks of the most severe service and handles all
trains in the tunnel at Baltimore.
Fko. 03. Electric Locomotive used in Baltimore tunnel by B. h O. R.R.
The 6000 or ''Mohawk** type of locomotive adopted by the New York
Central R.R., shown in Fig. 94. differs from others in having four gearlea
motors mounted directly upon the axles. The armatures are not even
spring suspended, but are keyed solidly to the axles. The dead weight
per axle is said to be less than in the case of the larger types of steam
locomotives. The fields are bipolar and are so arranged that the same
flux passes through the four sets of fields in series, returning partly thnMgfa
jthe side frames and partly through an overhead longitudinal frame. Ine
departure from the previous methods of construction, using geared motois,
is pronounced, and exhaustive tests seem to prove its wisdom for the pro-
posed service. In Fig. 05 are given the motor characteristics of the 650
ELECTRIC LOCOUOTIVES.
I HI
III
111
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742
ELECTRIC RAILWAYS.
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ELECTRIC LOCOMOTIVES. 743
hoTM-poi™ nwtor. E1(. 06 (JTM k •pceimBi ^wed nin ol tha SOOO looo-
motive luuliac > (nia of 338 torn oi a toUl trvia wacbt of 431 t<uu. 1d-
cludlof tha locomotive itaslf. Tb* ipMd nuhed, S3 milaa itar bour. hu
■incB EflCD (T^tly OTCHded, ono run being made during wbioh a ap««d
of S4 mila per hour wu recxinlsd.
A loconwtire which li of partioular laMnat u (hat ibovn in Fig. 97.
{
ThiM ii equipped with four 250 hone-power Bngle-phue tearlav :
which an atianged for operation on dtber 600 volU dlrnct cur
11,000 lolU ■ncIe-phM* alteiTAting ouncnt. Thi* looomotive la the Brat A
id Uuitr-five (1&07). which the Weatinghouae El«ctric and Maoufactuhna M
Co. haiiupplied to the N.Y.. N.H. A HT R.R. ■
It ■• of the doubJe-truck lyjie and baa two (wiveliiii tnjcka with a wheel ^
1. M. Preliminary Speed Bud oT N. Y. C. Lo«oinotive SOOO.
■ u-nuigBioent eliminatn any danger
( Bmuturea of the moton ue buitt
round tha ailea and are coruiecWd b
d fitted into pockatg in the wheel huba.
rins supported from (he journal boira.
e trsck. rimi'
with Che Bpring aupp
obtainsd in the
MMBJble.
Y., N.H. A II. H.R. are equipped with an 11,000
re, but Ihoae of the New York Central JUUtomI.
r
)
)
744 ' -It ELECTRIC RAIL WATS.
^
ITAL.LATION OP ELECTRIC CAR TiiOTORS. 746
h,e tndns must run from Woodlawn Junction to Grand Central
•quipped with a direct current third rail. For thii reason
otives are arranged to operate from either of theie conductors
ee from one to the other without alaokeninc speed,
rs are cooled by means of an air blast forced through them by
n blowers in the cab and on Uiis aooount they are oapable cm
200 horse-power each continuously, although an ordinary raU-
of the same nominal rating could operate continuously at only
liorae-power. The performance of the motor is shown by the
1g. 90. p. 717.
;ht of the locomoUve complete b approximately 88 tons. A
is capable of handlini^ a train of 200 tons in local service or a
) tonB in through service, and two or more units may be readily
lether and operated as one for handling heavier- trains.
AXAJinoir ov suBcn^ic cam motor*.
(General Electric Company.)
ing the various parts of the equipment and in wiring the oar, par-
Bntion should be taken to secure the following results :
tenanee of high insulation.
usion of all foreign material, particularly grease, dirt, and water,
ileotrical eaimpment.
ikvoiding oi fire from arcs, naturally occurring at fuse-box, light*
ter, etc.
prevention of mechanical injury to the parts.
pladng of the parts so as to be accessible for operation and inspee-
yet out of the wny of passengers.
Preparatloa of ^m €)mv
lor should be provided with a trap-door of such sise as to allow as
BS as possible to the motors. Particular attention is called to the
ity of haviiuE the bar across the car between the trap-doors remov-
irder that the top of either motor can be thrown back.
>of ^oiild be provided with a trolley board which strengthens it.
teets in case tne trolley is thrown off; it also deadens the noise,
upport should be provided for the Ittht clustera Grooves should
or the* leading wires in the roof molding, and also in two of the
osts, one for tne trolley wire, the other for the ground wire of the
eirouit.
closed csr four 2-inch holes should be bored through the car floor
le seats, one as near each comer of the car 9fl possible,
le ride of tiie ear, four f-inch holes should be bored in a line, and 4
part, to receive the taps from the cable to the leads of motor No. 1.
«t location of these holes depends on the type of motor used. The
» from the center of the axle to the center of this group of holes
be about two and one-half feet for G. E. motors. On the same side
Bar, and in the same Hne, four other f-inch holes should be bored
i apart, to receive the taps from the cable to the resistance boxes,
other side of the car three f-inch holes in a line and 4 inches apart
be bored to receive the taps from the cable to the leads^ of motor
and on mme aide of car and in the same line five other f-inch holes
s apart ihould be bored to receive the taps for the trolley, resistance.
ant for Motor No. 2. . - . , . i,
renoe ihouki be made to diagram in order that each set of holes shall
the pwpet ride of the car, and at such a distance from side-sills as to
of the way of wheel throw.
i
i
746 ELECTRIC RAILWAYS.
MeMoriag about 38 inches from the hrake-ataff and a snitablo dtrttiicw
Inside of the dash rail, au oval hole 6 in. x 2] in. should be cut in each plsO-
fonn to receiye the caoles.
On an open car no holes need be bored for the floor wiring ezoq»t tboao
through tne platf on&.
iMitalllaiir C«Btvoll«ra.
In the standard ear equipment one controller Is placed on each platforaa
on the side opposite the Drake handle, in such a position that the controller
spindle and tne brake^tatf shall not be less than 96 inches, nor more duui
40 inches apart. The exact position depends somewhat on the location o(
the sills sostaininff the platform. The feet of the controller are deeifmed to
allow a slight rocking with the sprins of the dasher. Two one-half inch
bolts secure the feet to the platform. An adinstable ansle iron is furnished
to be used in securing the controller to the aash-rail. A wire guard ia idao
furnished, to be secured to the platform in such a position that the cables
pass through it into the controller. A rubber gasket Is furnished with each
controller, to be placed between the wire guard and the platform,to exclndo
water. For dimensions of controller, see figs. 104 and 105.
This work can be conrenlently divided into two parts ; namely,
wtriMir *^^ floor wlrlMgr*
vrlrlag* includes the running of the main circuit wire from the
trolley throughboth main motor switcnes down the corner posts of the car
to a suitable location for connecting to the lightning arrester and fuse box ;
also wiring the lamp circuit complete, leaying an end to be attached to the
ground, wheneyer wires lie on the top of the roof, they need not be
coyered with canyas or moulding,, except to exclude water where they
pass through the roof. In such cases a strip of canyss the width of thm
moulding, painted with white lead, should be laid under the wire, and oyer
this and the wire should be placed a piece of moulding extending far enough
in either direction to exclude water. The moul<ung should be flrmiy
screwed down and well painted.
The aboye wiring should be done if possible while the oars are beine
btillt. ^^
Floor wtrtaf may be done after the ear is oompleted without inlnrlBc
the finish.
HsUio «p cskMoe giye £sr better protection to the wiring, and are
easier to install than separate wires, and should be used in the floor wiring
tf possible. The simplest way of installing them on box ears seems to be as
follows :
After the car bodies are prepared according to the aboye instructions, the
cables (one on each side of the car) should be run through holes in the plat-
form, and the connections made to the motors and controllers.
After making connection to the controllers, all slack should be polled tip
inside of the car under the seats, and held in place, preferably amnst the
side of the car, by canvas or leather straps. Motor taps snould project
through the sills for attachment to the flexible motor leads just far enough
to permit easy connection, leaving as little chance as possible for vibration.
No rubber tuoing will be requireaon taps, as they all have a weather>proof,
triple>bralded cotton coverins outside of the rubber insulation to prevent
abrasion. All joints should be thoroughly soldered and well taped. The
Grtions of the cables passing under the platforms should be supported by
Lther straps screwed to the floors or sills. Cables should never be bent
at a sharp angle. The ground wire should run under the oar floor rather
than under the seats.
On open oars all wires and cables must be run under the car, and should
be well secured to the floor with cleats or straps.
A good Joint can be made by separating the itraadf of the tap-wire, and
"^
INSTALLATION OP ELECTRIC CAR MOTORS. 747
vnpping the two iMutt In opposite direetion* arouud the mAtn wire. Both
Qk<Mut« and rubber tape are loriiiahed. It is desirable that Okonlte ibottld
be med flnt and rubber tape put over it, as the latter will not loosen and
mwrsp SB Okonlte will. AU openings in the hose should be sewed up as
tightly SB possible around the wires.
Sepnmte wlr«e can be installed if neeessary, obserring the following
directions :
The floor wires on box oars should be placed under the seats as much as
possible. In the few places where it is necessary for wires to cross, wood
should intenrene in preference io a piece of rubber tubing or loop in the
air. This rubber tubing is not necessary where wire is cleated under the
floor (as on open cars), if it does not pass over iron work, or is not ex-
posed to mud and water. Where so exposed, it should be ooreredwith
moulding, but where moulding Is used it should be carefully painted inside
and out with good insulating compound to exclude water. Tne wire passing
to the fuse box should be looped oownward to prerent water running along
the wire and into the box. Care should be taken to aToid metal work about
the ear in running the wires, and that nails or screws are not driven into
the insulation.
la g«aeral it is not desirable to use metalllo staples and cleats for ear-
wiring, except about the roof, or Inside the car. wnere wires are subject
to vibration, as between the car bodies and motors, flexible cable must id-
ways be used. A certain amount of slack should be left in the leads from
the motor to the ear body, depending on their length. On cars with swivel-
iiig trucks a greater amount of slack is necessary. As slack gives greater
opportunity for abrasion, care should be taken to leave only what u Abso-
lutely neoenary.
OpevAtlOM sMid Care af CoMtr«11«r.
When starting, regulate the movement of the handle from point to point
IO as to secure a smooth acceleration of the car.
not rmm botweoM p^tata.
The resistance points Ist, 9d, 8d, 6th, and 7th, are intended only for the
•nrpoee of giring a smooth acceleration, and should not be used contin-
onsly.
For oontinoous running, use the 4th, Sth, 8th, and 9th points, which are
liown by the longest bars on the dial.
When using the motor cut-out switches be sure tha^ they are thrown xtp
I far up as they will ga
In ease the trolley Is off and the hand-brakes do not hold the car, an
nei^ency stop may do accomplished by reversing the motors, and turning
te power-handle to the full speed, or next to full speed point.
To examine the controller, which should be done regularly, open the
rer, remoye the bolt with wrench attached, and awing back the pole-piece
tbe magnet.
rhe contact surfaces and fingers should be kept smooth, and occiwionally
•ated with a small amount of vaseline to prevent cutting.
All bearings tfurald be regularly oiled.
A repellent eompound, paral&ne, rosin, and vaseline, equal parts by
iffhtt, placed in ue water-caps of the power and reversing shaft, is an
i<nent protection against water.
>lrt most not be aflowed to collect inside of the controller.
"MBtm^^wmmtm mf Car Wirlair*
1 general car wiring is carried out in about the same manner for all
aa and sixes of car. more particular description being civen above. Wir-
differs mainly in details, governed by the number, style and horsepower
notora iiaed.
{
ELECTRIC RAILWAYS.
>DUBr>nu ot »laiul>nl vlrlng for two motora per ctz and for tour motorf
per eu follow In Flfi. W.W, 100, 101. Tber ue bII from the O. X. Co. lUU. ai
•OBtroUen made by UiM Compttnj ue ilmoM ■mlTerullT' med, ■Hhtrnffc
BUST of older deaign bj oltaar mnpaoln are lUU la tbe field.
\
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if
I
:ng diagram of elbctric cab uotobs. 749
II hmu.
i
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iiifi
ELECTRIC RAILWAYS.
ii .
lu
1
il
I
IING DIAGRAM OF BLECTKIC CAR MOTORS. 751
i|
lil
11 I
is .
ill
= 8
752
BLBCTTRIC RAILWAYS.
The following is a lUt of material required for tho electrical equipEnani cf
one car fitted with two motors:
QUANTITY.
1
1
2
1
1
1
1
1
2
1
1
76 ft.
20
10
30
25
110
25
25
100
lib.
lib.
1 lb.
480 ft.
100 ft.
41
64 ft.
Ih lbs.
4Ibe.
Ulbs.
Trolley pole.
Trolley base.
Motor circuit switches.
Li^tning arrester.
150 ampere magnetic out-out (fuse-box).
Resifltance box.
Resistance box.
Core for kicking coil.
Controllers (includes wire guard and gasket, supporting bracket^
cap screws, and washers for fastening to dasher).
Controlling handle.
Reveraing handle.
One of each of these handles is always shipped with each pair at
controllers unless specified to the contrary.
No. 6 B. & S. strand wire (7-.061 in.) for roof-wiring.
100 or 150 ampere fuses.
Two-way connectors, i-inch hole. No. 6.
Brass comer cleats, i^inch slot.
Brass flat cleats, ^inch slot.
i-inoh No. 4 R. H. brass wood screws for brass cleats.
Wood cleats, i-inch slot.
Wood cleats, |-inch slot.
li-inoh No. 8 R. H. blued wood screws for wood cleats.
Solder.
|-inch Okonite tape.
1-inch adhesive tape.
Material for set of cables as follows:
No. 6 B. & S. strand wire (7-. 064 inches), single braid.
No. 6 B. & S. strand wire (7-. 064 inches), triple braid for taps.
Brass marking-tags.
l^-inch cotton hose.
Rubber tape.
Paragon tape.
Solder.
This material can be procured made into a
out extra cost.
Car-lighting equipment.
'set of cables" with.
CONTROLLBKS.
Undar tlili twadlnc are included ^,tl>At type nf mppliapM lued for aUrlJiic
* "n abudan
of thou QDW Id use be mttecapt«-
on the old fDmu of rheintat with ditleniDt atep* luve bean abftndaned fi
the fo-CLllcd teriet-paraU^ cod' •■•■•'- -- ^ "
But DDS form a now in Eananil uaOt via., the mamgiic bimB-out type, nuile
by the Gsnsnl ELeclrio Company ud used also by ^a WntiafhauH Eleotrie
and JCanufacturins Company
ciul of line and extioEuiahed or out in two. Tbia fact
in tba etmcnUar of tGe Qeaent Electric Company by uains a strong electro
uunat to extincuiah the area fonoadat thecontact-pointa, when the oircuita
anbrokra. Tm eooatruotion la ahowa is the cut ol seriee-panllal oontroUa,
Pnim K3. fciIklwlDC-
._.i J- ; fgpjQg ^j variolJ« that it ta im-
le United StatM.
> by (he WMtiagbouaa Eleolrie and UanufaoturinE Compaay.
i
i
The prinoiple of the mainetio blow-out type waa Srat developed by F
''lu thomaon, i.e.. that an eleotrip are in astpng macnetio Geld ia bk
>
ELECTRIC RAILWAYS.
The GflfumL Elflfltho Compaay nuuiifurtuTtt
mm painllal
toJnutioD into fivfl foier^ cJaoaM, ewth deBign&l«d by ui vbiUs^ |c
I^VC ■ Con«r»li«>ri may be of «th« tha aeria □anlU ot i
fealuts of shuatina at abort circuitini; ong nl a
irom Mriee to iMnll«l oonnectioa.
"rjpe Ii Caatr«llen an kIh ot Ihe aerin pusUd typB, bat
oom[>let«ly open tba power oinniit wbcm -h^njinj from aeriea to puuM,
Fra. 103. "R"Typs(if RbeoetitleCootndtar.
TjlM n C*B*niIIen a» of tba rheostktio type ftnd are deucnid
•n*i Vjr* "■. Cfntral STateaa devalnped by the Ganenl
in trains, is hIao suitable for Dperstinn of larRe eguipmente, wher« the aiie
snd weidht of B cylinder type controller are objectionable.
This system of control cansiitii eeffiotisUy of & number of eleotrieelly
motor circuits, and which are in lum eoBtroUed by anull nueler oontrollen
which ate called upon to oarry only the current for the openling ooila al tba
oontsclora. The molatn ace reverwd by eleetrieally operated reverdiit
Bwit^n olao controlled by the master controller. When equtpmeqta are
operated (ocetber In trains, the control cintuita are oooneetad betwen
■diaoent oan by suitable couplen and the opention of the oontooton and
reverHiB on alt the can in the train am motrolled ilmultaneoualy from an/
muMr eontroUer on the train.
CONTBOLLEBS. 7&6
M VArallal Gwatrallan.
K9«ctrlc BnkB C)»B(r*II«ira
Title.
0-^". rsa-
RemarLa.
fr^
"«.S„"
!&
gupewded for Eonanl um by the B-13.
B-7
Tm 100 h.p.
^d5-
Haa aepanta brake handle.
B-S
'"ai"
Hu Mp>i>te bmha handle.
B-13
'"..S.'"
? &■
SuprniHi™ the B-3 from which it diffm in
lo render the aliidiUrut of the car wheela
756
ELECTRIC RAILWAYS.
Ml«ctrlc Brake Co»ir»llen.«-Coiifinii«r.
Title.
Capacity.
Controlling
Points.
Remarks.
B-18
Two 40 h.p.
Motors.
4 Series.
4 ParaUel.
6 Brake.
Similar to B-3 but arranged for rheostatic
braking only.
B-19
Four 40 h.p.
Motors.
5 Series.
4 ParaUel.
7 Brake.
Similar to B-^ having separate handles for
power and brake. Supersedes B-6.
B-23
Two 60 h.p.
Motors.
5 Series.
4 ParaUel.
7 Brake.
Similar to the B-13 but has oonneoting
wires and blow-out ooU of larger oapao>
ity.
B-29
Two 60 h.p.
Motors.
5 Series.
4 Paralld.
7 Brake.
Similar to B-23 but haa separate brake
handle.
Electric braUIng is made Uttle use of owing to the fact that it adds
siderably to the beating of the motora. The conditions are such thai the
motors are already over-taxed and the use of brake oontroUers neoeasitates
an increase in the siae of motor required. Air>brakes are in almost uni-
versal use on the heavier cars owing to their smaUer expense of installataon.
itetic CoBtr«llen.
Title.
Capacity.
ControUing
Points.
Remarks.
R-11
One 50 h.p.
Motor.
6
For motors using shunted field for running
points only.
R-14
Two 35 h.p.
Motors.
5
Very short and speoiaUy adapted to mining
locomotives. Motora connected perma-
nently in paraUel.
R-16
Two 80 h.p.
Motors.
6
Moton connected permanently in paraUel.
R-16
Four 40 h.p.
Motors.
5
Similar to R-15 but has reversing switch
arranged for four moton. Motors eon-
neoted permanently in paraUd.
R-17
One 50 h.p.
Motor.
6
R-19
Two 50 h.p.
Motors.
6
Similar to R~17 but has reversing switch
arranged for two motors. Motors eon-
nectea permanently in paraUel.
R-22
Two 50 h.p.
Mot-ors.
5
Similar to R-14 but has connecting wiiw
and blow-out coil of larger capacity.
R-29
Four 25 h.p.
Motors.
6
Similar to R-19 but has reveraing switch
arranged for four motors. Motors con-
nected permanently in paraUel.
R-37
Two 50 h.p.
Motors.
6
Similar to K-22 but has extra contacts on
the reversing switch for connecting the
motors either in series or paraUel.
R-38
Two 35 h.p.
Motors.
5
Similar to R-37 but has connecting wirw
and blow-out coU of smaUer eapaoity.
R~48
Four 75 h.p.
Motors.
8
R-55
Two 150 h.p.
Motors.
7
Has series parallel reversing switch same as
R-37. It is speciaUy adapted to mining
locomotive service.
These controllers are used with sin^e motor equiiMBaits or for loeo>
motive work where the speed is very low, as in yara snif ting servioe.
CONTROLLERS.
757
3
5
M
Z
e4
2
A
CO
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e
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<noQHhOHMiJ:0OP4tioQ:3>^M
>
ELECTRIC RAILWAYS.
ML LJ
at
Pm. km. TypeK. Flo. 106. Type L.
Tr%
i-- !
id L.J h— — —J.
^^■^^j
FiQ. lOe, Type B. Fro. 107. Typ. H.
Dialniiu tor DinwiuwiM of CoaUollem.
CONTKOLLEBS.
759
•
m
I
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t-
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s
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g cc eo*5? r" w* 3J o o*o» "df^o oo'«S'd"tS'^ :
•
760
ELECTRIC RAILWAYS.
MOTOR COMBINATIONS
■OTCH
it
4
9
II
^DtmTROLLlM
K_« MO K.il
ma. MOTOR 1 MOTOR ■
—UL O »H» O tH^
-Ptn O %Wf O ¥>W
-Qfll 0 MW> O %#>
-MnV*-o <iii» o WW
fc-t^flj O" "wwl o-¥w»l
l-^J o <w»l| o-
i
if
a
ic
II
I
umn
eBNVNflUKIH
'k IS AND K 1.1
RU.MOTOR I MOTOR I
— {nil o ***** o ^w>»
-Qtyi)— Q ¥w»i
-Qftn— o wnM
-Mnft— o Miw> o »mf
-HHJMkj ¥W o ^iwiip
-OhflT-o -^^i-o '***^^
-J-flm-t^ ^M»lpO ^(Wf ^
FlO. 108.
ifl
II
oom-noujni
"^mH^ 4w» ^fcQ-'iwp-*
II
II
11
MRIU Lf CONTROLLCR MULTI^LC
RU.MOTOR 1 MOTOR •
■^NUir-
-O Wf O %»W
■O %iMf 0--^Wi»-
iBi 0 ^MW o ow
NROUr OPCN
CMANOU TO MULTinf
WE NKXT OOCUMN
FlO. 109.
1
ELECTBIC MULTIPLE UNIT CONTBOL. 761
Tlie multiple onit control is dMicned primarily for the operation of motor
oars in tndn«. Motor cars and trau ears may be coupled in any combination
and tlie whole operated as a unit from any oontroller on the train. The
■ystam may also be used to adrantage on mdividual equipments and looo>
motives.
The control apparatus for each motor car may be considered as consisting
esseatially of a motor oontroller and a master controller.
The former comprises a set of apparatus, — usually located underneath
the car, — i^ch handles directly the power circuits for the motors, con-
necting them in series and parallu and oommutating the starting resistance
in series with them. This motor oontroller is operated electrically and its
operation in establishing the desired motor connections ia controlled by the
motorman by means of the master controller. The latter is similar in con-
struetion to the ordinary cylinder controller and is handled in the same
manner, but instead of effecting the motor combinations directly, it merely
controls the operation of the motor oontroller.
Tike latter consists of a number of electrically operated switches, or ** con-
taoton" which dose and open the various motor and resistance drouits,
and an deotricaUy operated reverser" that connects the field and armature
leads of the motors to rive the desired direction of movement of the oar.
Both the contactors and reverser are operated by solenoids, the operating
eurrent for which is admitted to them by the master controller.
In addition to the motor and nuwter controllers, each motor and trail ear
is equipped with train cable consisting of nine or ten individually insulated
eonauctors connected to corresponding contacts in coupler sockets located
at each end of the cars. This train cable is connected identically on each
motor ear to the master-controller fingers, and the contactor and reverter
operating coils; and the train cable is imtde continuous throughout the train
by couplers between the oars, connecting together corresponding terminals
in the oouplw sockets.
AU wires carrying current supplied directly from the master controller
form the "control circuit;" those carrying current for the motors, form the
"motor" or "power drouit."
Inaonuch as the motor controller operating coils are connected to this
oontrol train line, it will be appredateci that energiring the proper wires by
means c£ any master oontroller on the train, wul simultaneously operate
eorresponding contactors on all the motor cars, and consequently establish
similar motor connections on all oars.
In case the "power" circuit is momentarily interrupted for any reason,
the system of oontrol provides for the immeaiate restoration of the motor
and resistance connections, which were in effect immediately preceding such
interruption. Should the motorman remove his hand from the operating
handle of the master controller, the current will immediately be cut off from
the entire train, thus diminishing the danger of accident in case the motorman
should suddenly become incapacitated. The system must be supplied with
a potential of at least 300 volts to insure sucoenf ul operation.
The approximate total weight of control equipments, exclusive of supports
is as follows :
Aggregate H.P. of Moton. Weight of Equipment in Pounds.
125 1500
250 2000
400 8000
600 4500
800 6000
The approziiiiate weight of the apparatus for each trail car, which included
train eaUe, coupler sockets and oonneetion boxes, is 100 pounds.
The position off the handle on that master controller which the motorman
is operating always indicates the poeition of motor-control apparatus on all
ears. The motor controller wliioh handles all the heavy aromg is located
underneath the car.
r
The fBDcn] deaicn of the nvenwr <■ Minievbat etmiUr lo thmt el tbi
magnetj for throwing Et to either tomiil or nvase pcaitloTi. In aatrtti
oonslructioQ, the op«™iin» coils are limtlaT to them ined on the ODaloeton,
but in order to secure reliability of ncllon the mil ig wiraa full tins potential.
The leTBTflaf ii providHl with em>ll Gngere for handiiiw <nntrD)>«iretIJt
connectioiw nnd when it throwi, the apenting mil is diwDnDMitad fma
arDDDd and is pUoed In Mries with ■ *ee of eontutor Doib. tlin> ovMnt Ifai
EIiECTRIC MULTIPLE UNIT CONTBOL. 763
I (
ELECTRIC HAILWATS,
C aurrent down loanfe ninninc vilua. Thn* ooib
e, which will opan the oiTcuil If Ihe revsner full (o '
of th« revuHr doe* not oorrttpond to Ch« dirsotion
■■rgbed, uid
: thnxriiic.
113. kUaMr Controller Sprwuc G. E. Uiillipla Onit SyiUm.
Her Is ooBodaniiij ■'B>l|^
M hudlea uo pfovidad. u
iety. open-«irouiling devioB ia provided, whf(<d>T, is mm
amuD mnoveii hii hand from the iiia«ter-oontit>ller IiadcUb, 1^
lireuit will be mutonutioUy openad by mMJU of knxilluT eonlwli
mtroUer. phiflh are operated by a flpnns when the bii"~ "^
I releued. Thb device ig eniltely Mpatste uid diitiDot
t of the mmin oylindar. Uovinr "■" i.-ji- j.
« handle dtber forward
iwer handle ia median inall)' In
^
ELECTRIC MULTIPLE UNIT CONTROL.
765
ment when the revene handle is removed, it is only necessary for the motoi^
man to oairy this handle when leaving the oar.
When the master controller is thrown off, both line and ground connections
are cut off from the operating coils of important contactors, and none of
the wires in the train cable are alive.
The current carried by the master controller is about 2.6 amperes for
each equipment oi 400 horse-power or less.
Fio. 113. Details of Top of Master Controller Sprague Q. E. Co.. Multiple
Unit System.
nUMstor C«Btr«ll«r Awltcli. — A small enclosed switch with magnetic
bk>w^<nit is used to cut off current from each master controller: and it is
rallied with a small cartridge fuse enclosed in the same box. When this
BwitcAk is open all current is cut off from that particular master controller
which it protects.
MrMffg O^auiMctiOM. — A noteworthy feature of the- control is
the method of aocomplishina the series-paraUel connection of the motors.
liida is by the soHsaUed "Bridge" method of connections, which are so
arranged that the circuit through the motors is not opened during the tran-
sition fnvm series to parallel and substantially the full torque of both motors
is preserved at all times, from the series to the full parallel connection. This
eonaeetion does away with any serious falling off in the rate of acceleration
irikioh is sometimes noticed when the motor circuit is interrupted during
tratt^tion from series to parallel in other methods of control. The " Bridge
eonneetion is therefore partieulariy adapted to hich rates of accelera^on
ivfaieh oan thus be sustained throu^out the accelerating period without
aausing diseomfort to passengers.
766 ELECTRIC RAILWAYS.
^\t/t 9mr-fm9 O
/ ^'ryt, ^»oilrf^ ^
fO
Fia. 114.
MUM.TKPI.IS COMTBOI..
The system of multiple unit oontrol developed by WeBtinshouse Eleotrio
and Maoufacturing Company employs a combination ol electromacnetie
and pneumatic devices to produce a method of controlling from a sin^
point a single car or train of care, all or part of which are equipped with
motors. It is applicable alike to alternating and direet-onrtent okoton,
and to double and quadruple equipments. It may be airanged for either
automatic or non-automatio ac(»leration and for operation with or without .
a train bus line.
The complete equipment oomprises apparatus pertaininc to the main
control system, which operates the motors on eaon independent oar: the
auxiliary control system, which consists of the Qleotrio circuit whieh aotuates
and controls the various devices but is entirely separate and diatinot from
the main motor control system; and a number of nfety devioea and attach*
ments which protect the apparatus and safeguard its operation.
JHaln Control. — The active element of the main oontrol syatem
is made up of the following apparatus:
WESTINGHOUSE MULTIPLE CONTROL. 767
A group of unit awitohes whieh regulate the supply of current to the
motore.
A set of reeiatances or an auto-transformer whioh ia used in oonneotion
with the unit-switch group to control the supply to the motor.
A line switch which controls the main supply of current to the unit-switoh
group.
A reverse switch whioh govema the direction of car movement.
iLsxAliAsy CoMtrwl. — The auxiliary control system derives its
>perating energy from a storage battery which forms part of each car equip-
ment, and actuates the main control through the intervention of compressed
air dnwn from the brake supply. It oompriaes the following apparatus:
The master controller.
The train line.
The line relay switch.
The series limit switch.
The control cut-out switch.
The auxiliary control regulates the operation of the main control by the
action of the master controller which governs the circuits connecting the
storage battery mains and the valve magnets which regulate the air supply
to the switches of the main control system. By the admission of air to the
opfltrating cylinders of the switch group, the motors are connected in the
desired oomoinations.
Asritclt Oroap. — The switch group consists of a number of powerful
circuit-breakers mounted in a common frame and assembled with their
air esrlinders in such a manner that when a valve magnet is energised the
air win be admitted to the cylinder, forcing the piston forward and closing
the switch.
The switch contacts consist of two heavy L-shaped pieces of hard-drawn
copper which close the circuit first at the tip and then roll and slide on each
other, finally resting at the heel under the full air pressure. The switches
are opened by the action of powerful springs. As their normal i>osition is
open, any fauure of the air supply or interruption of the circuit is accom-
panied by the immediate opening of all switches. A magnetic blow-out
assists in the breaking of \,he arc.
]ft«sUtence or Auto-tnuufomser. — The main control resist-
ance consists of a suitable number of grids mounted in frames and so
connected to the unit switches that theyj'egulate the current flowing throu^
the motors as the switch group advances through its oyole of operation.
With a single-phase altematingKnirrent railway equipment an auto-
transformer may be used in place of a resistance to regulate the voltage
supplied to the motors.
JLilii« Awrlteli. — The line switch comprises a group of switches —
one for each motor of a double equipment or each pair of a quadruple equip-
ment — connected each in circwt with its motor and carrying the current
of that circuit alone. Their construction ia similar to tnat of the units
f9rming the switch group, except that each has an independent magnetic
dreuit lor the magnetic blow-out and is provided with an automatic trip
whieh opens and renders inoperative the auxiliary control whenever the
oxrrent in the blow-out coil becomes excessive, allowing all the switches
of both the line switch and switch group to drop out.
■^•▼•■w* ftwiteb. — In the direct-current reverse, an insulating
block carrying two seta of metal strips arranged to make contact with sta-
tionary fingers is oi>erated forward and back in a strais^t line motion by a
pair Of pneumatic pistons which form part of the auxiliary control. The
o|Mrating oytindeis are governed by magnet valves which are interlocked
with those of the switch group in such a way that the reverse can be thrown
only when the main control circuit is open.
The reverse for alternating-current equipment is of the drum type.
HalM •witeb ami Fine. — As an additional safeguard a switch
and foae may be introduced in the main line to open the circuit in case the
automatic overload trip should fail, or if a ground or short circuit should
oconr on any unprotected portion of the main control system. When it is
open the oonneotion between the third-rail shoes or trolley and the main
oontrol apparatus is broken.
Haatoi' Coatrollei*. — The master controller consists of a mov-
able drum and stationary contact fingers. The handle is brought to the
I
>
ELECTBIC RAILWATB.
■1 or "oS" poaition bjr the m
. ,__ .. . .. wane (rf tliB HI .
iBtarlsck HwUcltmm, — The interlook ai
MuUiBiy poiilraLiyileia,Di>iiiti( (4 tpriof.oo '
ontroller huicUa. Whan i'
iiIIOD HI lot mr DT tnja at InWnnadut* p
iini>ly ToovBd off the et ' '
■nd ar* dMtrioallv oonDsotod with tha nucnat ralvai ia nch ft miiTwr that
the dosinc of one energiHa the valve mecoFt itf (he iwiUdi next BueeeadiBf
produoiotf an aulomatio progrmiva aocLoa which ptovulfH a unifQrra aeoir
eiali^mlb
VrttiB ]
eiteod throi^u .», -^.^..^ ..u.^. »b««.« « . —
tMkata and jumper*. It ooooeoM the aevenl portkNM of tba aiufliwr
*ral> 1,1m. — The train lini
•xleod through the entire train, tocether with the .
ooBttol syatsm to the nonse 1stt«rl« by whUi the opsntluK cumnt b
■nDplisd. The pcTtantiKl of th«g drouiU u mbout 14 volts.
fJMtriCBl oonDoottOD b«tvwD osbln al Adjoining can is [ormed by miwu
of soaketa parmfnently mounted on tbe ends of the cars and s jump« whiofa
»■■ parmfnently mounted on tbe ends of the c
M o( a psir of Maci oonneoiiid by « ahort piec
<**r OtrntT^TCut-vrnt IHrlMlb. — To i
— . ,-jvidBd with ewib eqmpmmt. It oon-
a drum with copper ne^uenta vhicb make ooatact with
either side and formiag part d the auxilijLry aontroL
•wltoh. — Rasulatian of tbs motor ourrent durini
Ml IB >wvmpli«bed by a amall switch in the auxiliary oontrdl
eirvi^t govcnilnf the progressive aotioa of the unit switcheSj throu^ the
lliA pivsreaaive adtioa of tbe awit4ih sroup arreated wbeoever the cunent
neeods a pre-dstaimiaed limit. When the current afain lallg below this
Hmit. the iwitoh doeee by gr&Tity and the proEreHive action of the awiteh
BTOup U oontinued.
Ua« Belay. ^ To proleot tha melon from an abnormal rush of
eurrml in ease the main Gne eircuit Is suddenly msUblialuid after Inter-
ruption, a line relay Is intriKtuced in the eontromas ■yHtem and arraneed to
onan the unit Bwitohex in oasa of failum of the line supply, but a held eloied
I interrupted. This action takes place on each
___ , the ourrent suifply ig interrupted on any car the
■witoh Roup on that ear will be out out independently oi all other cars in
tbe train, atid U the surreat supply Is rwtared while the master eontroller
ia ID a running position, the line relay will reatore the battery oonneotion of
tfae ODDtrol ebeuit and the switefa croup will then pass throuch ite eyol*
S««r^r* aaftorlM. — The i
.. r .1 1 .._. : u, ^ _ ^
potential ol t
esidi eonsisiiu vl sevea eSta. The i
ifl about 14 volts. One battery is on „ — , —
the air ooiDpressor or the car liKhting sysleni whjja thi
^-^ ve and negative rf tbe ti
bAttflnea of the several ears are therffore connected in pa
nerative side is also oonneoted to oi ' ' '' '-■-----■---*-
toaking th ' ......
>n the batteries
■witeb croup may b« operated thraufh its oyele tor the purpoee of I«t
"buek the raoCors and effect a audden stop In an emergency.
The »e*)nd or overiowl trip reeetswiloh is normally held open by asjl
or eoasting podlion^^any trip that may be open will be ™eel-
•wn thqn^ die trolliN or third-rail afaDea of any car be not in nonlaot
necteil from oar to ear by jumpers, i^ugs and sooketa.
■aaaai mt tke AdrBatag** GlalwMI.
A oontrol power wholly independent of tbe line power and voltane.
SafMy secured by the impossibility of short drcuiia, the line power eo
beii^ local to eaoh oar.
Ataenee nl trouble with oontrol circuit oonlacts.
Low potential train line, practically eliminating tram hn* troubh
ihort drcuiM of the oontrol system.
Qreat power at the switcb contacts, made available by the use of
pressed bit. which secures greater carryina capacity and permits the i
powerful springs which insure nperation of tbe switches under au oondi'
Effective oircuil-bTeaklng devices with powerful magnetio blow-outa
Absolute independence in tbe regulation of Ihe eurronl input of eacl
Antomatic letoni of tba nuUo oontrol to the "off" position jf die en
770
ELECTRIC RAILWAYS.
supply of any or all oars fails, and automatic return to action when the
current is restored.
A main control which is not brought into action by the auziuary oontrol
whoi currmt is cut off. . - * -
A main control which may^ be operated ^en the power is off for the pur-
pose of test or to stop the train in an ecuOTsency.
ft03CIMAVl! RATKS OF DEPRSCIATKOflT
(Dawson.)
to
It
2%
9
10
<<
<4
(I
((
tl
10
30
6
8
6
n
14
4i
U
• •
<4
((
««
Buildings 1
Turbines 7
Boilers 8
Dynamos and Engines,
belted plants ... 6
Belts 25
Large, slow-speed steam
engines 4
Large, slow-speed direct-
arlven plants ... 4
Stationary transformers, 5
Storage batteries in cen-
tral stations . ... 9
Trolley line 4
If interest rate is 5 per cent, and plant has to be renewed at the end of 20
years, 3 per cent of original outlay must be reserved annually to provide for
renewal.
mSPRECIATIOM OF 0VREET RAnWAY IHA-
CIKIIVKRir AlVR fii^lIEPRSHV.
tt
11 "
8 "
Feeder cables ....
Lighting and current
meters 8
Cars 4
Repair shop and test-
room fittings ... 12
Motors 6
Rotary transformers . . 8
Boilers and engines . . 6
Spare parte H "
Track work 7 •'
Bonding 6 "
On remaining capital ex-
penditure 4
3 to 5%
14
10"
6*'
15"
8"
10"
10"
2"
13"
10"
4«
Street Rail
R»tea Stated by Chlcaffo Cl^ S^JJl'^'g: *"
v»*wM«>.fttAtloB. Engines, 8 per cent ; Boilers, 8 per cent ; Gene-
Powei>»<»n<»>* ^ ^^^ 3 _^ ^^„t . Buildings, 6 per cent.
Cable Racklaery. Cable machinery, 10 per cent ; Cables, 176 per cent.
-•^ -- - ^ Rails. 5.5 per cent ; Ties, 7 per cent.
Granite, 6 per cent ; Cedar blocks, 16 per cent ;
Brick. 7 per cent ; Asphalt, 7 per cent ; Macadam,
6 per cent.
Car bodies, 7 per cent ; Trucks, 8 per cent.
Armatures. 33 per cent ; Fields, 12 per cent ; Gesx
cases, 20 per cent ; Controllers, 4 per cent ; Com-
mutators, 33 per cent.
Wiring and other electrical equipment, 8 percent.
Iron poles, 4 per cent ; Wood poles, 8 per cent ; In-
sulation, 12 per cent; Trolley-wire, 6 percemt;
Trolley insulation, 7 per cent ; Bonding, 8 per
cent.
All based upon renewals and per cent of wear.
RolliBor stock
I«iae Eqnlpvieiit.
CAR mSATIlfA mr n.SCTRlCXTV.
Vest oa Atlaatlc Avenae Railway, Rrooklya.
Cars.
Temperature F.
Watta
Doors.
Windows.
Contents,
Cu. ft.
Outside.
Average
in car.
Consumed.
2
2
2
2
4
4
12
12
12
12
16
16
850^
850
808
013
1012
1012
28
7
28
35
7
28
66
39
49
52
46
64
2296
2325
2180
3746
3088
3160
TRACK RETURN CIRCUIT.
771
VKACK JUBTVlUf CUeiTXT.
It so«t without saying that the return circuit, however made, whether
throush track alone or in connection with return leeders, should be the best
possible under the circumstances. Few of the older roads still retain the
bonda and returns formerly considered ample and good enough.
Eleotrolsrsis and loss of power have compelled many companies to replaoe
bonds and return circuits by much better types. The British Board of Trade
psdd especial attention to the return circmt in the rules gotten out by them
(see page 781)| and many American railroads would have been much in
pocket to-day if such rules had been promulgated in the United States at
tl&e beginning of the trolley development.
With few exceptions the praetioe of engineers has been to connect the rail
joints by bonds, ooth rails of a track tofi^ether at intervals, and both tracks
of » double-tiaok road together. To this has sometimes been added track
return wires laid between the rails, and in other cases return feeders from
seeticHis of traek have been run to the power house on pole lines or in ducts
underground.
The writer favors the full oonneetion return with frequent insulated over-
head return feeders where there may be danger from electrolysis of water
and gas pipes; in fact, ample return circuit has been proved time and again
to be the only preventive of that trouble.
On elevated nulways where the structure is used for the return, the ends
of abutting longitudinal girders are likewise bonded together at the expan-
sion joints. Tests have shown that the riveted joints, where well riveted,
have a oonductivity nearly equal to that of the prder itself, henoe it is not
neoeseary to bond them. The return circuit of the New York Subway is
designed for an extreme drop of five volts.
Oareful and continuous attention should be given to bonds from the
moment oars are started on a line.
CaoeSMO or two BI.ICTKIC K^AOS CMSHNO or BLSCTIUC AMOSTftAll ftOAM
Fig. 116. Showing Gable Connections for Bonding Around ** Special Work."
Dr. Bell gives the following ratios of track return circuit to overhead
Bsrstem as being average conditions.
Let
Then
R, -
Ri "> resistance of track return circuit, and
.1 to .212.
.2 to .ZB.
.4 to .6R.
.2 to .3A.
.3 to .7R.
.7 to I. OR,
resistance of overhead system.
Exceedingly good track and very light load.
Good track and moderate load.
Fair track, moderate load.
Exceptional track and large system.
Good track, large system.
Poor track, large system.
772
ELECTRIC RAILWAYS.
In exceptional cm«s traek reeistance may exceed tbat of overhead aywUBL
It is sometimes assumed that Ri <— .2512, but this is rather better than
usual.
Under ordinary conditions J2i <— . 4i2 is nearer correct.
II / rwjrf
If formula for copper circuit -> cm. -• j= — - then for Ri -• . 4R, the
constant 11 should be increased to between 14 and 15 in order that copper
drop may bear correct proportion to that of the ground return.
Tjpe of
(Bt F. R. Sultbr.)
Bonds are divided into two general classes, (1) those which are faatened
to the surface of the rail or girder to be bonded, commonly called "aoldered"
bonds, and (2) those having terminals with a shank which is expanded into
a hole in the rail or girder to be bonded, commonly called "riveted" hoods.
In both classes that portion which is attached to the rail is called the tenninal,
the remainder the body of the bond.
tiolderod Boadis. — These are formed in varioos ways but in
general by a series of thin strips of annealed copper bent in the form of an
Fia. 117. Soldered Bond.
3
II — ST
^
Fio. 118. Bond Attached to Base of
Rail by Soldering only.
arch for the greatest degree of flexibility, with a pair of feet or terminals
to provide contact suiface. The stripe of each foot are soldered or welded
together, making a solid terminal, while the intermediate strips of the arch
are free and unattached to each other so that they can readily take up vibia-
tions. Figs. Ill and 112 illustrate this type.
Skawmiit 0«lder«id Boad. — This bond is constructed of copper
laminations .088 inoh thick, the ends separately tinned, clamped together
Fio. 110. Soldered Bond Applied to Head ol RaU.
FiQ. 120. Soldered Bond Applied inside of Angle Bar.
TYPE OF BONDS.
1, uid the form o(^
In applying wldsrsit
cKnnot beaierclied. T
p«rfActly mt the paint uf BpplLoatLon uid thi
Unned. The bonil li then oliinipad In uoaltli
mad iteaX sppilBd to bo"- '— -• '
antrnuM of tk double burner
polder being Applied with :
Bondacan bs applied to m
bMeo(an]l,u.d eanh or the
■bODld be able to wltbituid
■train of two thoDsand poondi ■heulBg
ifSTS
i
Pta. 122 Soldend Bond AppUed
^--••^* ^
off. The rige u
t. bood iDeLted o
SSTld
the imperfect Aolderi
774
ELECTRIC RAILWAYS.
— These are fonned of a length of wire or oable
having a oopper terminal pressed or welded to ite ends. Solid wir« bonds
of this type break easily from track vibration tf short, and are used most
lar^y for oonnecting around special work. This type of bond is sub-
divided into several styles, according to the way the shank of the tenninsl
is fastened into the hole in the rail.
1. Bolt JBKpfMidea VerBtlnttl. — In this one the shank of tbs
terminal is made with a hole through its center. Throui^ this hole is
passed a steel bolt ^Hiieh is threaded on one end and has a bevded slM>tt]dar
^^.niimini'iMW
&
Fio. 125.
on the other. After the shank is fitted into the hole, it is expanded by pull-
ing the bolt through the terminal by means of a nut, the tapered shoulder
expanding the shank into the hole. This is shown in Fig. 125.
9. PlM Kxpaaded Temslnal. — In this type the tenninal is
made with a hole through the center of the shank which is fitted into the
hole it is to occupy and a beveled steel pin is driven throuf^ its center,
expanding the shank to a tight fit. This is shown in Fig. 126.
Fio. 126.
Fio. 127.
These two types are used principally for bonding the channd rails of the
conduit system of electric railwajTs.
In both t^pes the shank of the terminal should practically fit the hols
before the pm or bolt is driven in.
3. Maoltlae JAlT«ted Vernitii»ls. — In this type the shank
of the terminal is made solid and is compressed into the hole by meaiks of
mechanical or hydraulic pressure (Fig. 127).
Terminals of bonds should never be riveted by hammer as the shank is
Fra. 128. Poorly Riveted Tenninal. Fio. 129. Well Riveted TerminaL
not properly expanded into the hole (Fig. 128). An imperfect contact
increases the resistance besides making the bond liable to further deteriora-
tion by reason of the accumulation of moisture between the shank and the
hole. By means of the compressor the back of the terminal is first held
securely against the face of the rail, then the shank of the terminal is ex-
panded, forcing the soft metal back toward the base, making a uniforai
contact throu^aout the thickness of the rail, filling the hole so ooxopletdy as
TTPE or BONDS.
776
D Iha tool mu-ki o
thB diilL sndmoraa
Mlb iiuniuia tha
_- _ ol tha button hnd
(kubM by UM oomprCBMir (Fiz, 129). This oontaot suifiuie iii im nuoitUl
l«Btaie, mud the sffimcney of tha band depeodi upon ttiu eonDectlon bdni
Tata allow that it takaa twioa the power to turn the oompr^Hed tcnninal
Id Ita bole that it don M tuni the pin-drivan terminal. Aa the onl^ reaist-
th« aidea of tba Itola. the oomprtaiied terminal must have mueh the aupeiior
Fio. 130.
Fisune 130 a
Fio, 131. Fio. 133,
npeetivelv the doubl»«crew Bad hydimiilie
booda in the tjose cl tha nil.
le body portion of
3. Ita body portion ahould be ek> oonatruoted aa to poaatn mmcLeat flex
ibility to withetand all ribrationg to which it may be aubjecled. such m
haamer blowe. of paaains ear wheata on tl
(raetion cS the niils due to temperature vi
4. A method of applying the bond whJ
he bonds as little axpoaad aa ]
th«r bein« elolen. This b |
Etonda should alao be made i
776
ELECTRIC RAILWAYS.
desirable that the bonds be placed ander the splice plates whenever poooibleL
In new installations standard splice plates are now procurable which hare
ample space between their inner surfaces and the rail to allow for the bonds,
and in ohanjKing over old installations the saving in the initial cost of the
bonds and the saving from loss by theft wiU go far towards pajdng for new
splice plates.
With the idea of placing the bonds under the splice plates, manufacturers
have designed them in suitable shapes, either by flattening the strands.
Fia. 135.
or the use of flat wires in the strands. Figures 133 and 134 show eitder
rails with bonds under the splice plates, and fig. 136 shows a standard"** T '*
rail stndlarly bonded.
ItMUataace of Bonds. — The total resistance of a bond is oom-
posed of three factors, the resistance of the copper in the bond, the resistance
between the body of the bond and the terminal, and the contact resistance
between the terminal and the rail. The following table ^ves the resistance of
some of the more common siies of bonds used:
Sise
of
Bond.
Length of Bond.
6"
6"
7"
8"
0"
10"
0
00
000
0000
.000047
.000030
.000033
.000028
.000056
.000046
.000038
.000032
.000064
.000052
.000043
.000036
.000072
.000059
.000048
.000040
.000081
.000053
.000053
.000044
.000080
.000073
.000050
.000048
For any given sise of bond the only variable factor in its resistance with
the lengtn is the resistance of the copper in the bond, the other two factors
remaining constant. Hence the resistance of different sises can be plotted
as is done in Fig. 136, using resistance in ohms and length in inches
as ordinates.
At least \ inch extra length of short bonds should be allowed for extreme
contraction of rails due to changes in temperature, and bonds shorter than
0 inches are liable to excessive breakage due to vibration.
The most common practice has been to have the bond holes drilled at the
rolling mills. Hence, when it is desired to do the bonding, the holes are
rusty and will need to be reamed out until clear and bright. The cost of
having the holes drilled at the mill at the current price ($1.00 per ton of
rail) usually amounts to about 20 cents per hole, ana the reaming to about
6 cents per hole — a total of 25 cents per hole, while if the holes are drilled
just as the bonding is done, they will cost about 7) cents each, including
tools and supervision. Punched holes cost about 4 cents each. Theee
costs will vary with conditions and rates of wages, the above being based
on $2.00 for a day of eight hours. There is no material disadvantage in
drilling the holes with oil.
{ I i
RESISTANCE OF BONDS.
BE8IBTAHCE in 0HU8
>
ELECTRIC RAILWAYS.
lUlcr the bo]« have bcsn pnipErly prepared lbs lurfuic of the meul
■luface tor the bsw of the leimin&l on the one side, ud the buttoD head,
when riv9ted» on the other, Jf (be nh&nk of the temiinAl beiumM oxidiBaa
or dirty it nhould be cleaned before being put into the nil.
Tklrd RaU BsmIIbc.— The practioe in Ihiid imil boadinc hu beta
rmil nBaHy'«™un'ifonn''modu^.",li ■""""""
iron eplics plalM are used wbicb allow luffieienl
137 nhoWB the bondini of the third nil of (be 1
Company (New York Bubwmy).
Iittia trouble ia axpenennd by broken Joints or bent nili, Theaa *r« not
pnctieable on third mila or track raila that ere not ambeddad and Ihu*
axpoaed to all temperAture ehanEes.
In (be eleclricklly welded iiyiiteni an iron plate in welded acron the joint
on each side of the rail web by means of heavy eurt^nt of electricity applied
by apecial low voltage machinery.
The cait weld joint ii simply a Urge lump of >t«el cast about the joint
in a mould after the rail ends have been cleaned.
V»r»»w *»lMfc— (Sire* RaQicau Joumof.) The Voynow joint con-
eiflte o( what may b« called two special ehannd ban whiea are riveted (o
the ends of the rail. Theea plates are not made to fit tbe Bshing »e-
tion of the rail; on the contrary, spaoes ara loft uDdnt- (be head, tram
and around the foot of the rail. The flat surfaces of botb siiiee of Iha
rails and of (he joint bam having been previously cleaned by sand-blast.
theMspaces are ailed with molten sine, which entera into and fills out all the
irregularities of the rolled lurfacea, (bus giviaE a oontinuous bearing (brough-
out the wllc^e langlb and width of the ftangee of the plates. The adhesion
of the molten sine to the rails and plHles, toffelber with tbe body-bound
expanrion. thus making rails continuous. ' As (be rail ends and inside of tha
plates are eleantd to tha metal by sand-blast, the joint is atio of the beat,
electrically considered.
Tkemlt Hall-Woldliar. — The thermit process is a pur^v cbemi-
eal operation, based upon the fact (bat melallio aluminum, under proper
tbe iron free. As (he pri>e9is of reduction libentee a p«at amount of beat,
6000° F.V changins the iroa to a moltea low-oarbon ila^. £x[H«aad in
RESISTANCE OF TRACK RAIId.
779
tifht proportion, and introduced into a crucible lined with macnesia, or
with material obtained from a previous fusion. In order to set off the con-
tents of the crucible, a small quantity of ixnition powder (barium peroxide
and pulverised aluminum) is put in a smalTheap on top of the mixture, and
is isoited by means of a match or red-hot iron rod. The reaction propagates
itself quickly through the whole mixture, with the result that in a few seconds
the whole charge is a mass of white-hot fluid material. The contents of the
erueible have separated into two layers, the molten metal reduced by the
altuninum being at the bottom and the molten almninum oxide above it
In the application to rail-welding, a cone-shaped crucible, with magnesite
lining, is mounted on a tripod over the joint to be welded, a proper^ pre-
pared iron sand clay mould havinfj^ been previously clamped around liie joint.
The conical crucible has a hole m the bottom, and bdore the operation a
small iron rod or pin is placed in this hole with its end projecting several
inches below the crucible. Above the head of the pin in the bottom of the
erueible is first carefully fitted an asbestos washer, and on top of this is
placed a solid ciroular metal washer to hold it in place. About 15 pounds or
20 pounds ai powdered aluminum and oxide iron are then poured into the
crucible. This mixture is known as "Thermit," and is furnished properly
mixed and ready for use in small ba^ by the manufactures. On top of the
mixture is placed a quantity of ^ition powder, about enough to cover a
50-oent piece. When all is readjr, a match is applied to the powder and a
conical cover with a central opening is hastily placed on the crucible. In a
few seconds the reaction commences, and witnin thirty seconds the contents
of the crucible become a seething, boiling mass of molten metal. As soon
as the reaction has reached its height, a man strikes the pin projecting from
the bottom of the crucible with a rod or smaU shovel, driving the pin upward,
thus freeing the hole and allowing the molten metal to flow down into the
mould around the joint, depositing a mass of metal around the joint and
welding the ends of the rails into one piece.
i
i
ReslstaMce of Track Rails.
The resistance of the commercial steel track rails is about thirteen times
that of copper. On this basis the following table of resistances of rails is
computed.
Weicht
Sectional
Equivalent
Cir. Mils
Resistance
Area
per Mile
Rail.
Sq. Inch.
of Copper.
Ohms.
45
4.4095
431.883
. 13074
50
4.8904
479,884
.11766
65
5.4874
536,034
.10602
60
5.8794
575.605
.09806
65
6.3693
623.887
.09051
70
6.8592
671,825
.08404
75
7.3491
719,380
.07844
80
7.8392
767,763
.07354
85
8.3291
814,873
.06922
00
8.8190
863.766
.06537
05
9.3089
911.767
.06193
100
9.7988
1,072,068
.05883
Area in cir. mils «
EUiuivalent cir. mils of copper —
1.000,000 X weight per yard
10.2052 X .7854
Area in cir. mils
13
780
BLBCTRIC RAILWAYS.
BRIMSim von DBTBrnHKNTATIOM OS* THB
lUBiiAxrrK vai.uk of RAJXS A1V1»
BOITOKD jroKirxA.
(W. H. COLB.)
Fifteen rails were used, ipving three joints for each of the five different
daeses, and in makin^E the tests and observations an average of the rwults
for the three rails of its class was given. Micrometer calipers were used in
measuring the wear of the rails each month, three different measurements
were made at each place, and an average was calculated from theee three
measurements, vis.:
A. At a point at or near the sage line.
B. At a point in the center ca the tread.
C. At a point near the outside of the rail.
The joints that were bonded were fished with standard fish plates, bolted
with ei^ht 1-inoh bolts, screwed up tight; the rail ends butting each other
were laid, fished and bonded in the maximum heat of the day, and imme^
ately covered and iMived around them.
No. 1. Three joints fished aa above and bonded around the fish (>iateB
with standard Chicago bonds No. 00 B. A S. gage, two bonds to each joint.
No. 2. Bonded with "Grown" concealed bonds, with two bonds of a
section equal to two No. 00 copper B. A S. gage, and the fish plates bolted
over them.
No. 3. No. 2 plastic bonds, made by Harold P. Brown, and carefully
installed according to instructions, by a man formerly experienced ior this
work.
No. 4. Three joints welded by the Falk process.
No. 5. Three joints welded by the Qoldsohmidt thermit process.
The rails were laid continuously so the same cars passed over the same
section containing the different types of joints. The subjoined tables
give the results, from which the wnter has arrived at the following con-
clusions:
That for dectric street railways under average traffic conditions* raik
should give a life of about forty years if the joints are made continuous, and
are composed of
Carbon 56 to .58
Silicon 10 or under
Phosphorus 08 or under
Sulphur 06 or under
Manganese 83 or under
iMrvedisnte of Iftalla Uaaer Test.
Carbon.
Carbon
Silicon . .
Phosphorus
Sulphur .
Manganese
Iron . .
Soft.
.284
.061
.105
.065
.784
1.299
98.701
100.000
Medium.
.572
.235
.052
.078
.981
1.918
98.082
100.000
Hard.
.591
.057
.098
.060
.830
1.636
98.364
100.000
NoTB. — Metalloids ignored.
I
BOARD OF TBADE REQULATIONS.
781
The f oUowing would be the eleetrioal effioieney and Icmb at the besinniiis
and end of the firat year:
Class of Joint.
Chioaflo bonds
Crown bonds
Plastic bonds
Falk cast weld . . . .
Goldsohmidt thermit weld
Electrical
Percent
Efficiency
at Ban-
ning of
Year.
80.51
86.71
80.72
101.16
101.14
Electrical
Efficiency
at End
of Year.
74.43
73.72
77.84
86.53
100.39
Per oent
below
EqiualSeo-
tionof
RaU.
29.67
26.28
22.16
10.44
100.30 +
MOAMJ» OF TRAAB RadDXiATMOliS.
For C»r«at Brltialau
Begnlations prescribed bv the Board of Trade under the provisions of
geotion — of the — — >- Tramwavs Act, 189—, for regulating the employ-
nient of Insulated returns, or of uxunsulated metallic returns of low resist-
ance; for preventing fusion or injurious electrolytic action of or on gas or
water pipes, or oUier metallic pipes, structures, or substances; and for mln-
ImiMg, as far as is reasonably practicable. Injurious interference with the
electric wires, lines, and apparatus of parties other than the company and
the currents thereiia, whether such lines do or do not use the eartn as a
return.
l^ilBitloiia*
In the following regulations :
The expression " energy ** means electrical energy.
The expression ** generator" means the dynamo or dynamos or other
electrical apparatus used for the generation of energy.
The expression " motor ** means any electric motor carried on a car and
used for the conversion of energy.
The expression *'plpe" means any gas or water pipe, or other metallic
pipe, structure, or suMtance.
The expression ** wire ** means any wire anparatus used for telegraphic,
telephonic, electrical signaling, or other similar purposes.
The expression " current " means an electric current exceeding one-
thousandth part of one ampere.
The expression " the company " has the same meaning or meanings as in
the Tramways Act, 189—.
JRegvlatioaa,
1. Any dynamo used as a generator shall be of such pattern and oon-
stmction as to be capable of producing a continuous current without appre-
ciable pulsation.
2. One of the two conductors used for transmitting energy from the gen-
erator to the motors shall be in every case insulated from earth, and is
hereinafter referred to as the ** line"; the other may be insulated through-
out, or may be insulated in such parts and to such extent as Is provided in
the following regulations, and is nereinafter referred to as the "return.**
3. Where any rails on which ears run, or any conductors laid between or
-within three feet of such rails, form any part of a return, such part may be
uninsulated. All other returns or parts of a return snail be insulated,
nnless of such sectional area as will reduce the difference of potential be-
tween the ends of the uninsulated portion of the return below the limit
laid down in Regulation 7.
4. When any uninsulated conductor laid between or within three feet of
the rails forms any part of a return, it shall be electrically connected to
the rails at distances apart not exceeding 100 feet, by means of copper
782 ELECTRIC RAILWAYS.
strips having a seotlonid area of at least one-sizteentli of a square inela, or
by other means of equal oonductivity.
6. When any part of a return is uninsulated it shall be connected wltli
the negative terminal of the generator, and in such case the negative termi-
nal of the generator sliall also be directly connected, through the currooit-
indicator hereinafter mentioned, to two separate earth connections, which
shall be placed not less than twenty yards apart.
Provided that in place of such two earth connections the company may
make one connection to a main for water supply of not less than three
inches internal diameter, with the consent of the owner thereof, and of the
person sum>l3ring the water ; and provided that where, from the nature of
the soil or for other reasons, the company can show to the satisfaction of an
inspecting officer of the Board of Trade that the earth connections herein
specified cannot be constructed and maintained without undue expense, the
provisions of this reffulation shall not apply.
The earth connections referred to in this regulation shall be eonstmetad,
laid, and maintained so as to secure electrical contact with the ffeneral
mass of earth, and so that an electromotive force not exceeding four volts
shall suffice to produce a current of at least two amperes from one earth
connection to the other through the earth, and a test shall be made at least
once in every month to ascertain whether this requirement is comoUad
with.
No portion of either earth connection shall be placed within six feet of
any pipe, except a main for water supply of not less than three inches In-
temal diameter, which is metallically connected to the earth oonneetioos
with the consents hereinbefore specified.
6. When the return is partly or entirely uninsulated, the company ahall,
in the construction and maintenance of the tramway (a), so separate the
uninsulated return from the general mass of earth, and from any pipe in
the vicinity ; (b) so connect together the several lengths of the ruls ; (e)
adopt such means for reducing the diiference producM by the current be-
tween the potential of the uninsulated return at any one point and the po-
tential of the uninsulated return at any other point ; and (d) so maintain
the efficiency of the earth connections specified in the prececUne reffulations
as to fulfill the following conditions, vix.: ^
(1.) That the current passing from the fearth connections through the in-
dicator to the ffenerator shall not at any time exceed either two amperes
per mile of single tramway line, or 6 per cent of the total current output of
the station.
(2) That if at any time and at any place a test be made by connectinir a
galvanometer or other current indicator to the uninsulated return, and to
any pipe in the vicinity, it shall always be possible to reverse the direction
of any current indicated by interposing a battery of three Leclanche cells
connected in series. If the oirection of the current is from the return to the
pipe, or by interposing one Leclanche cell, if the direction of the current is
from the pipe to the return.
In order to provide a continuous indication that the condition (1) is com-
plied with, the company shall place in a conspicuous position a suitable
{>roperly connected, and correctly marked current indicator, and shall keen
t connected during the whole time that the line is charged.
The owner of any such pipe may require the company to permit him at
reasonable times and intervals to ascertain by test that the conditions
specified in (2) are complied with as regards his pipe.
J\.Y^f^ ^^t return is partly or entirely uninsulated, a eontlnuons record
shall be kept by the company of the difference of potential during the work-
ing of the tramway between the points of the uninsulated retuni furthest
from and nearest to the generating station. If at any time such diiference
of potential exceeds the umit of seven volts, the company shall take imme-
diate steps to reduce it below that limit.
8. Every electrical connection with any pipe shall be so arranged as to
admit of easy examination, and shall be tested by the company at least once
in every three months.
9. Every line and every insulated return or part of a return, except any
feeder, shall be constructed in sections not exceeding one half of a mile in
length, and means shall be provided for insulating each such section for
purposes of testing.
BOARD OP TRAD£ REGULATIONS.
rent iball not aioeed one-huudredtb ot ma iimp«r« per mile of ti_u....
Tha lukua oamDt itull b« MCartatDsd dally, berors or mftw tbe boon ot
1 — -^-in (he lino l» folly charged. If»t anytime It (hoald befoand
..» .,,^..^1 «»__!. — .^i..i. ^ .J, atnpg„ pg, „)], (,[ inun-
■!» praetloble, and tha
tI thin TwoDty-f our hoars. Protlded, tbBi wbsre both line and return ai*
plaoad vithin a conduit tbli regnlallon ahall not apply.
11. The Insulation teglaUnce of all oontlnuously LnsDlated cablca need for
Unea, for Ininlatod returns, (or feeden, or for oflior pnrposoB, and laid be-
low tha BUrfBoe of the ground, ■hall not be penntlted to fall below the
aqnlTstent n[ 10 megohms for a length of one mflc. A teat ot (he Insulation
12. Where In any cue In any part ot the tramway the line Is erected OTcr-
hwMl and tbe return li laid on or nnder the ground, and where any wire*
luTe been erncted or laid before the eoottrnctlon ot the tnuaway, In the
panjehall. If required to do no by ttie owners of such wires or any of them,
permit ■Dob owners to Insert and maintain In the company's lice one or
more imlnelton coils, or other apparatna ^>prr»'ed by the company lor the
pnrpose of prerentlng dlstnrhance by electric Induction. In any case In
which tbe company withhold their approTal of any eoch apparMns, the
owneni msT appeal to the Board ot Trade, who may. it they ttilnk lit, die-
dispense with BUcb apprnval-
13. Any Insulated return shall be placed parallel to. and at a distance not
eioeedlut three feet from, tbe line, when the line and return are both
erwted overhead, or 18 Incbes when tbey are both l^d undergroand.
U. The company shall so constroct and maintain their gystema as to
•eonra good aoDt*o( between (he motors, and the line and relum reepao-
UTOly.
tf. Tbe oompany shall adopt the best meant arallable to prayant the oe-
eurrence of undae sparking at the rubbing or rolling contACts. in any place,
17. In working the cars tbe current shall bo varied as required by menu
ot a rheoelut coDtolnlng at least twenty sections, or by some other equally
efficient method of gradually varying reelstani
18. Where the line or return or both are lal , _ _
conditions shall be compiled with In the construction and malulanance '
kid In a conduit, the (ollowlug
_, — _-f-.. „^j — ],., leeof
(a) The oondull shall be so constrocted as to admit of easy examination ot,
and access to, the conductors contained therein, and their Ineulatort
(by It shall be BO eonetrnctad as to be readily cleared of accumulation of
dust or other ddbrls, and no inch aocumulatlou shall be permitted to
(c) It shall be laid to such fBlls, and so connected to sumps or other means
of drslnueos to automatically clear itself ot water without danger
of tbe water reaching the level of the conductors.
lay If tha conduit Is formed ot metal, all separate lengths shall be so jointed
currente. Wl.ere the rails are us'ed to (orm any par t of" the ^return,
uieh, or other mearw of equal conductivity, at dlHtaneee apart not e^-
oeeding 100 feet. Where the return is wholly Insulated and contained
within the conduit, the latter shall he connected to earth at the gi
arating station through a high i '
the indlcatlDn of any or partial co
wl(h the eoudDlt.
784 ELECTRIC RAILWAYS.
(6> If the oondalt is formed of any non-metellle material not being of hi^
insnlatinff quality and iraperriooa to moisture throughout, and it
I>)aoed wfthin six feet of any pipe, a non-oonducting screen shall be
nterposed between the conduit and the pipe, uf such material and
dimensions as shall prorldethat no current can pass between them
without traversinff at least six feet of earth; or the conduit itself shall
in such case be flned with bitumen or other non-conducting damp-
resisting material in all cases where it is placed within six feet of any
(/) The leakage current shall be ascertained daily before or after the hours
of running, when the line is fully charged, and if at any time it shall
be found to exceed half an ampere per mile of tramway, the leak shall
be localized and removed as sood as practicable, and the running of
the cars shall be stopped unless the leak is localised and remored
within 24 hours.
19. The company shall, so far as may be applicable to their system of
working, keep records as specified below. These records shall, if and when
required, be forwarded for the information of the Board of Trade.
Number of cars running.
Maximum working current.
Maximum working pressure.
Maximum current from earth connections (ride Regulation 6 (1) ).
Leakage current {tfidt Regulation 10 and 18/.).
Fall of potential in return {pidt Regulation 7).
Moailily liecorda.
Condition of earth connections {vide R^^lation 6).
Insulation resistance of insulated cables (ride Regulation U).
4(vart«rly Record*.
Conductance of Joints to pipes (ride Regulation 8).
Occaaloaal Records*
Any tests made under provisions of Regulation 6 (2).
Localization and remoyal of leakage, stating time occupied.
Particulars of any abnormal occurrence affecting the electric working of
the tramway. ... , ,
Signed by order of the Board of Trade this day of 188
Assistant Secretary, Board of Trade.
^
OVERHEAD CONDUCTING SYSTEM. 785
0ir»TJBH OF SJiBCVMIO SAU^^TAYS.
Dr. Louis Bell sives the following steps as the best to be followed in
e&iaring upon the oaleulation of the oonduoting system of a troD^ road:
Extent of lines.
Average load on each line.
Center of distribution.
Maximum loads.
Trolley wire and track return.
General feeding system.
Reinforcement at special points.
It must be said at once that experience, skill, and good judgment are far
better than any amount of theory in laying out the conductmg system of
any road.
Much depends upon the charaoter of the load factor, i.e., the ratio of
average to maximum out-put; and this, varying from .3 to .6, can only be
judged from a study of the particular locality, the nature of its industries
and working people, the shape of the territory, and the nature of the sur-
rounding oountry.
Map out the track to scale, noting all distances carefully, and dot In
any contemplated extensions, so that adequate provision may be made in
the oonduoting svstem for them. Note all grades, glvinff their lensth, gra-
dient, and direction. Divide the road into sections such as may best sng-
Sest themselves by reason of the local reqnirements, but such as will make
he service under ordinary conditions fairly constant.
The average load on each section will depend, of course, upon the
number of cars, and the number of cars upon the traflic. This can only be
arrived at by a comparison with similar localities tdready equipped with
street railway, and even then considerable experience and keen judgment
of the general nature of the towns are necessary in arriving at anything
like a correct result.
If the road has been correctly laid out as to sections, the load on each
win be uniform and may be considered as concentrated at a point midway
in each section. Now, if a street railway were to be laid down on a per-
fectly level plain where the cost of real estate was the same at all points,
and wires could be run directly to the points best suited; then it would only
be necessary to locate the center of gravity of the entire system, and build
the power station at that point, sending out feeders to tne center of each
section. Unfortunately for theory, such is never the case; and cost of real
estate, availability of the same, convenience of fuel, water, and supplies
will govern very largely the selection of a location for the power-house.
Even when all the above points necessitate the placing of the power-house
far from the center of gravity of a system, it may be possible to use such
center as the distributing point for feeder systems, and even where this ia
not possible, it is well to keep in mind the center, and arrange the dis-
tributing system as nearly as possible to fit it. i
All this relates, however, to preliminary determinations for the system
as determined at the time, and in large systems will Invariably be supple-
mented by feeders, run to such points as the nature of the traffic demands.
A baseball field newly located at some point on the line not known to the
engineer previous to the installation, will require reinforcement of that
particular section; and often after a road has been running for some time,
the entire location of traflic changes, due to change in facilities, and feeder
iystems then have to be changed to meet the new conditions, so that after
ail, location of the center of distribution depends largely on Judgment.
The maximum current will rise to four or five times the average where
but one or two care are in use; will easily be three times the average on
'pads of medium sixe, while on very lai;^ systems it may not be more than
double the average. If speeds are maintained on heavy grades the maxi-
mum is still further liable to increase.
Another point to be considered in connection with maximum load is the
location, not only of heavy grades, but of parks, ball-grounds, athletic fields,
wmetenes, and other such places for large gatherings of people that are
Qftble to call for heavy massing of care, many of which must be started
786 ELECTRIC RAILWAYS.
praotioaily at the sitme time, and for which extm feeder, and in eome
extra trolley capaoity, must be provided.
Having determined the average current per section of track, the majdmnm
for the same, and the extraordinary maximum for ends, park looationa, etc^
as well as the distances, all data are obtained necessary for the detemuua-
tion of sixes of feeders.
The sdection of the proper size of trolley wire is somewhat empirical, bat
the sise may be governed by the amount oi current that is to be carried. It
is obvious that with given conditions the larger the trolley wire the fewer
feeders will be necessary, and yet with few feeders the voItagA is liable to
varv considerably. In ordinary practice of to-day No. 0 B. A. S. and No. 00
B. &. S. gauge, hard-Klrawn copper are the sixes mostly in use, the latter on
those roads having heavier traffic or liable to massing of cars at oertain
localities. On suburban roads using two trolley wires in plaoe of feeden,
0000 B. db S. gauge will probably be best.
Track return circuit has been treated fully in a previous chapter (see pa|{e
771); and all that is needed to say here is, that some skill in judgment is
necessary in settling on the value of the particular track return that may be
under consideration, in order to determme the value of the constant to be
used in the formula for computing the sise of wire or overhead eireuit. In
ordinary good practice this value may be taken as 13, 14, or 16, aocordins as
the bonding and rail dimensions are of good type and huge.
It is quite obvious that the current-carrying capacity of the feeder must
be taken into consideration, in spite of any determination of drop; and this
can be found in the chapter on Condticton. Sixes of conductors are also
fovemed to some extent by convenience in handling, and it is found that
,000,000 cm. is about the largest tiiat can be safdy handled for under-
(ETOund work, while anything laxger than 500,000 cm. for overhead oircaits
IS found to be difficult to handle.
COlfXKiriJOUA CmUiKItT S'KSIDBItS rOAD DSVKlt-
MIMATIOM.
The first step towards determining the load is to draw a train _
from the propmeed time-table or scheoule of trains. Such a diagram, having
as abscissse the length of the line and as ordinates the hour of ue day.
shows in a graphic form the course of every train and the number of trains
on the line at any time. The stops may be omitted if they are very short
compared to the runs, but in any case it is usual to show the course of
each train by a straight line over each run, variations of speed being
ignored unless of considerable duration and magnitude. An example of su^
a train diagram is ^ven in Fig. 138, in which each train is indicated by a
special kina of line m order to illustrate how it travels to and fro. The load
at any time is estimated by counting how many train curves cut the line
representing that particular time. Knowing the average amperes per train
the total amperes are easily estimated for any time of day and may be
plotted in the form of a load dia^Eram. The average value of amperes for
this^ purpose is obtained by plottmg the curves of current for each run and
adding the ampere hours of all these runs. The total ampere hours divided
by the total number of hours occupied by the runs, is the average current
taken by a train.
The method of plotting the current curves is described on page 667.
Bconoiitlc»l ]!••%« of feeders. — The investmwit in a system
of feeders may be expressed as an initial cost, or as an annual interest or
percentage thereof. The value of the kilowatt-hours lost in the feeders is
most conveniently expressed as an annual expense. The sum of these two
annual items is the total annual expense of the feeders. If the ooet of
feeders be proportional to the amount of copper and if the energy loss be
computed for exactly the same part of the system as the first cost expense,
the total cost will be a minimum when the interest and energy iteins are
equal. This is known as Kelvin's Law. Unfortunatdy the conditions
which are necessary for the correct application of this rule are not usually
met with in practice. The cost of conauctors is seldom proportional to the
amount of copper owing to the existence of such items as cost of manu-
facture, installation and insulation. When, however, it is desired to find
the m<»t economical sise of feeder to connect to a trolley wire or contact
COSTINOOOS QU.MBT MEDBES.
ELECTRIC RAILWAYS.
the lost JD ihe fi
Mw »
lut by trial. A table sliowiiiB bow to do this is civen
ae uied in ootmectJoD with that on " DistributioD of
ea below. In ths fonntr I«ble the (jntem of moU
□ (.CtM 3) <rf the latter tabli^ ia anumed (o be inL
iry, and u not oven upplimble it then ia no drain at
, R.M.8. ^
i. .SS^
D tfainl
a — aquan root of ths mMui of ths ourrenta aguaied.
■.iKltlBr IPoMa*l«l Dr»p. — The total drop In ths poaitive and
negative fesSera is regulated by leveral oondiiiona aome d riiltii, unfo>
tunaldy, may bs eontrediotoiy. Tbs line volla«e must always be hich
li«hU bright. For a multipl»-unit syilem. Ihe Gm voltage muat be
auffloieat to operate the cootacton and air compreaAora with oerlainty
The General Electric Company'a tyi>a M ajratem of coolrol should have
at least 300 volu. The partoiasible drop is also influenced by ooDsiden-
tiona of ecnooniy, and in grounded feeden is often required not 10 noeed
a certain limit died by Uw, this limit varying according to the locality. In
Enj^and the maxinmm drop allowed in the grounded conduetors is eeveo
volte, whereas in mopt Ainericau cities no limit at all exists, it beiog only
nocSHaary for the railway campany (o take whatever preoaution may be
^Fwv ClaaMia at Verlldra. — Anv direct eurrent teeder ayitsn
eonsisU of two parla, the conductoni which carry the currvnt to the line
vey current to the cam. One .let of oonducton may be ao dsaigiied w to
fuRil these two functions, or Ihe lines from the power slalioo may be quite
from the power station carry the same current along Ihrir entire leniUi,
p. etc., may be treated by Ohm's L*w. Tlie
eontact oonduetore ii
df^ienda on (lie dJatributlcm o( 01
mentioned above
^
CONTINUOUS CURRENT FEEDERS.
789
Various amtngementa of feeder and eontaet oondttotora are shown in
„ ICi. 139, 140. 141. 142, and 143. Fig. 130 shows the simple ladder system
in which the f eeden and trolley wire are jMned at intervals so as to form vir-
FEEOn
TROLLEY Wim
TRAOKIirrURN
ciROurr
Fio. 139.
tuaUy a sin^e eonduetor. In its best form the eroes section of the feeder is
tapered according to the rules given below. Fi^. 140 shows a modification
of the last scheme. In this case the trolley wire is cut into sections, so
that while losing the extra conductivity of the continuous trolley, each section
TRACK RETURI
cmouff
Fio. 140.
may be cut out in case of trouble without depriving the remainder of the
systesn of current. Each section may be protected by a fuse and switch
or a circuit breaker, but it is a disadvantage to have such apparatus scat-
tered along the line. Fig. 141 shows a system where the current leaves the
TRACK RETURII
CMCUIT
Fig. 141.
L
TRACK RETQl
cmouiT
Fio. 142.
r
^
•
790
ELECTRIC RAILWAYS.
Btstion by several lines, thereby enabling; a number of small oirouit brsi^oKs
to be used instead of the larce one required b^ the other systems. It, how-
ever, has the disadvantage of oeing uneoonomiical in oopper, as the Ions lines
carry very little of the load near the generators. The system shown in
Fig. 142, IS in many respects ideal from an operating standpoint, but it is
very uneconomioal m copper and energy. Each section of the tiolley '~' —
, Station Bw
Feeders
Baa
Fia. 143.
or third rail may be controlled by a circuit breaker in the power station thus
giving the operators complete control in case of overload, short-circuit, or
accident of any kind. It is also quite advantageous to replace a large circuit
breaker by a number of small ones where thousands of amperes have to
.sue'
MIAVY MAMS *0
Q
TRACK RETURN
omcurr
FiQ. 144.
be transmitted. A combination of the last two ssrstems is where the sections
are connected by switches which can be opened in case of aoddent, but
are normally kept dosed. Fig. 143 shows a system that is useful for nega-
tive return conductors in cases where it is important to keep down the drop
■ALL PARKAT END OT UNt
TRACK RETURN
CIRCUIT
FlO. 145.
in the grounded rails. The numerous taps drain off the oamnt in theb
neighborhood and so prevent the current in the rails b^ng great at any
point. The drop of potential in these insulated feeders will be oonsiderable,
out in the grounded ones it will be very little. This is in some oases noore
economical and certainly more simple than a " negative booster."
CONTINUOUS CURBBNT FEEDERS. 791
The problem of determination of the proper size of oondnotors to be
used in diBtribnting the current for an electnc railway is somewhat com-
plicated by the fact that the load is moving or changing ite location all
the time, and more so by the always changing condition of the resistance
of the ground return, due to load, to track oending, condition of the earth
return, and nearness of water and other underground pipes. Owing to this
changing condition of the ground return part of the circuit it is necessai-y
to assume some arbitrary yalue for it, in comparison with that of the oyer-
head or insulated portion. The resistance of the ground return is seldom
as high as that of the orerhead part, nor is it often as good as .25 of that
value ; these values change with the load and track conditions, and it is
now most universal to use the factor 14 as a number which represents the
value of both overhead and return conductor, in place of 10.8, the resistance
per mil-foot of copper, and that value is therefore used in the formulso
for calculating the sizes of overhead conductors, and has been found to
produce good results in practice.
Let d mm distance from switchboard to end of conductor.
CM >■ cir. mils area of the conductor.
V «- drop in volts at far end of line.
/ >■ current.
JF — watts.
E -> volts at switchboard.
10.8 -■ resistance of arc mil-foot of commercial hand drawn copper
wire U 2ff C or eSP F.
14 — resistance factor, including track return.
% — per cent expressed as a whole number, as 10 or 20.
Then for plain feeders between switchboard or other source of supply
and the attaching point to the system.
CM^
V ■'
CM ^
1400 X rf X /
%X^
CM ^
1400 Xdx watts
% XB*
r-
14 X rf X /
CM
r.
% XE
100
The above formulso can be usQd for nearly all practical determinations of
feeder and other conductor sizes, but must always assume the load to be
concentrated at one point or center. For other formulie for calculation of
the size of conductors see chapter on conductors.
IMatribatloB of Garr«Bt. — It is usual to assume the drain of
current from the contact conductor to be uniform, so that the current at
any section is given by the ordinates of a straight line sloping down from the
power station. The error in this assumption is decreased on account of the
motion of the caxB as this causes the load to act as if more distributed.
INctrUb«tlon of Copper — As the feeders carrying the same
current along their entire length can be treated by the simple f ormulss shown
above, it is only necessary to consider those along which there is a uniform
drain of current. Four typical cases are shown in the table with their respec-
tive f ormuUe for circular mils, CM. ft., watts lost, and potential drop. The
following abbreviations are used.
Where conductors of iron or aluminum are used it is best to reduce them
to equivalent sections of copper.
The volts drop given by the formula are from the far end of the line; in
order to get the orop from the power station, the values obtained by the
fonnuUs must be subtracted from V.
792
ELECTRIC RAILWAYS.
'
tJntfomt lK«ta of Current.
AMPS.
CM.
Fig.
146.
Case 1.
Gondncior ITnifomi.
/T«^ _ 10.8X/X«
Watt8l08t = |/r.
Cif. ft.= 10 «^/''.
AMPS.
r\
CM.
FlQ.
147. Case 2.
CoHduotor
CnlfoHMly Tapered.
CM.
10.8 x/Xd
Wattd lost =
CM. ft.
10.8 X/XP
Volts drop =
10.8x/Xrf
CONTINUOUS CURRENT FEEDERS.
793
AMPS.
CM.
Fig. 148. Cue 3.
fjjur _2xio.8x/xVrxVa
CM ft ^^X10.8X/X^»
Watte loBt = I /r.
5
Volte drop = F x V-r
(7mAf,
CM. ft.
Fig. 140. Case 4.
«c«or IJiiifonn. Cnrr«nt I »« Atatioa and 1 a«
IHstaat Bad.
= "•«>«^+*>'. Watt, lost = JO«x^x(/'+iI+<^.
-* '^ Cilf. X 3
10.8X</+»W'
2 r
Totaldrop. r=-!?i^^^^.
794
ELECTRIC RAILWAYS.
In case 3. the formula for CM. gives the most economical dtstributioci of
copper to produce a certain drop V to the far end of the line. It is, of course,
impossible to get this exact arrangement in practice as conductors of definite
sixe must be used. The conductors are, therefore, arranged in steps of
AMPS.F
CM.
FiQ. 150.
decreasing area as shown in Fig. 150, each of which may be treated as an
example of case 4.
IlKtacelliaBeoiu Voraialfe. — Walla loat, <u8uming tuuform drain
of currenl.
Watts ■= amperes per foot X area of "Drop" curve in volt-feet.
Potenlial drop in uniform conductor unlh any distribtUion of currenl.
Volts » ohma per foot X area of current curve in amjpere-feet.
Mo^ economical distribution of copper unlh any diatrUnUion of currenl.
Cross section of copper proportional to ▼current.
NoTB. — Do not connect trolley wire to feeder too close to power line or sub-
stations, as if done this will cause frequent opening of circuit breakers.
]>rop and JLoaa, etc.. In Iilne l»«tweeB Two Anbatetlons of
Unequal Pot«ntl«U. Aaeomptloaa.
One train moving between S.S. with constant speed and constant current.
/ — current per train.
L = distance between sub*stations.
R » resistance of line per mile of track.
El <<- potential of S.S. No. 1.
Ea — potential of S.S. No. 2.
8.S. 1.
!S.
l2
s.a.2.
FiQ. 151.
IMPEDANCE OF STEEL RAILS.
795
mimisMi
Drop at Trste.
t\ 4
Dmmm
IRL , El - Et , (El - g,)»
2 "^ 4/ia.
/«i 2
I'l ) « :t ± gi -g«
Ex- E
2RL
2IR
I»r»p mt Train.
DmmiX IRL
Ex — E%
h\ 2
6 2
, E\ — E^
RL
between ••••
nRL . {Ex- B^*
6
RL
nnPEDAircB of stbsi. rau^s to
cvitiusirr.
The impedanoe of iron or steel oonduotors to altematiii|E currents is
a complicated phenomenon which varies with the frequency of the current
flowins with the area and the shape of the perimeter ot the cross section and
the permeability; and the permeaoility depends upon the current in the oon*
ductor; therefore statements of the impedance of iron or steel conductors
to alternating currents convey little true meaning without a statement of
all the conditions named above. Owing to the complexity of these con-
ditione it is practically impossible to compute the values which must there-
fore be determined by experiment.
FoUowing are tables showing the results of experiments upon steel track
raila.
Kxperimeatal I^terntlnatloa of Impedance of Steel Raila.
{A. H. Armatrongt O. E. Co.)
4&-poand Rail.
Measured cross section — 4 . 26 square inch. Perimeter — 15 . 875 inches.
Direot current resistance of 180 feet — .00371 ohm.
Cycle
Amps.
Volts
Power
Factor
Imped-
ance
Watts
Eff. Res.
React.
25
25
25
223.2
332
438
4.18
6.75
8.85
.834
.852
.864
.01875
.0203
.0202
776
1910
3350
.0156
.01735
.01747
.0103
.0106
.0102
40
40
40
223.2
332
438
5.37
8.8
11.47
.826
.876
.889
.0241
.0265
.0262
990
2560
4450
.0199
.0233
.0232
.0136
.0129
.0120
60
60
60
223.2
332
438
6.88
11.06
14.46
.850
.901
.877
.0308
.0334
.0330
1308
3305
5550
.0262
.0300
.0289
.0162
.0145
.0158
BLECTRIC RAILWAYS.
•O.paaml mil.
DD — 6 Hiuare inches. !
»oI LSOCeet— OOISf ol
Wfttls Eff. Ra. R<Mt.
»0-»*aB« r*ll.
I inoh. Perimator —
it naiBbuiM of 180 fast — .002036 obm.
38.
VolU
&,
Imped-
W«»
Eff. R«
Rmu*.
ik
.7M
,756
.834
;01665
8780
S
«
n'.as
:8M
!02I2
3440
12300
S
;S"
10. IS
.863
.0264
3430
MSO
15150
.0223
:2i
■Mt •> Xatcrworiu Trttclu sf WeaUavksHaa
■■ * M. C*.
o Jotermine the drop in voltage in a sirouit eompoMd nf a
id ■ pBir of track raib and to determine tiao the effect of the
kdditioD of ft feeder, the (hUowIiik tenia wen
made on the Wntiofftujuse Intenntrb R«U-
I ■ my. in March. 190K. The seotion ot the roiA
n ielected wiu 4000 fert long and oonsiated of 1200
" feet of double catenary oonetruetion and 2800
feet of smRle catenary conntniction. ThotroUev
wire was No. 000 and the trafk rails wen TO
pounds. The trolley wire waa M ftel kbore
the track on the double catenary portion and 23
(OBt on the aingle catenary. The maeseiiHr
; cable eoiuiiied of /^inch stranded steel cable.
' i A No. 0000 feeder waa lonaled appranmalriy 3
feet above and 8 feet to the side of the trcdlay
, 152. wlt«, as indicated in iketoh ffig. 152).
EXPERIMENT ON INTERWORKS TRACKS.
797
With the end of the trolley wire grouoded to the track and an alternating
current of 25 cycles appliea at the points B, C, the following results were
obtained, with the aid dL the No. 0000 feeder used as a voltmeter lead.
\
Total
Volts
Volts
Total Im-
Power
Amperes
volts
B -C
A - B
A - C
mdanoe
Factor
50
23.5
15.5
8
.47
.646
100
46.2
• ■ • •
• « • •
.465
.637
150
68.5
45
22
.456
.639
200
89.6
63.2
29.5
.448
.63
300
138.4
97
44
. 44o
.62
Average
.457
.634
On direct current the average resistance of the total circuit B-C was
.248 ohm; of the portion B-D, .219 ohm; and of the portion C-D, .0266
ohm.
It will be seen from the above that the drop in voltage in this circuit,
oomposed of trolley and track, was 45.7 volts per 100 amperes and that
approximatelv two-thirds of tins was due to the trolley wire and one-third
due to the raus.
In the second set of tests, current was supplied to the No. 0000 feeder
and trolley wire in parallel and with 25 cycles alternating current, the
following results were obtained.
Total
Amps.
Amperes
in trolley
Amps, in
feeder
Voltage
Imped-
ance
Power
Factor
100
150
200
51.5
72.7
95.3
48.5
77.3
104.7
32.5
48.4
63.2
Average
.325
.323
.316
.321
.553
.544
.54
.642
On direct current the resistance of this circuit was .1298.
It will be seen from these results that the addition of the No. 0000 feeder,
which reduced the resistance from . 248 ohm to . 1298 ohm, or nearly cut
it in half, reduced the drop with alternating current from 45.7 volts per
100 amperes to 32. 1 volts per 100 amperes or only about one- third.
This indicates that for single-phase railways the most economical use of
oopper is to place it in the trolley wire onlv and to so locate the feeding
points that proper voltage will be obtained.
In general, with a circuit consisting of No. 000 trolley and a pair of 70-
pound rails, the drop in voltage with 25 cycle alternating current is approx-
nnatdy 60 volts per 100 amperes per mile, but only from 60 to 65 per cent
of this voltaoB represents a loss oi enerflpr.
With the slternatinjc current system using a trolley and track return, there
is an inductive drop m the trolley and rails, with an additional loss in the
latter case due to eddy currents and hysteresis. Measurements made upon
tha Bailstoa line indicate an apparent trolley resistance of 1 . 8 times the
ohmie resistanee. and a rail resistance 6 . 55 times the ohmio resistance.
798
ELECTRIC RAILWAYS.
Coaip»TOttir« A. C.
»U« of Clr««lt.
Two troUeya in series ....
One trolley and double track .
Two trolleys and double track
Double track alone
DjC.
Resistance
Ohms.
.318
.167
.088
.0174
A.C. Resist.
25 Cycles
Ohms.
.417
.259
.155
.114
Ratio
A.a
DXl
1.31
1.55
1.76
6.56
The impedance of an deotrio railway conducting system oonsistinc of a
trolley wire overhead, placed in some sort of location above the two traek
rails, IS a still further complication, and this impedance comprises the resist
ance and reactance of the trolley wire, and if dT catenary construotioii, the
messenger wires; the resistance and inductance of the ruls; the inductance
of the circuit bounded by the rails and the trolley wire^ and the mutual
inductance of the currents in the two rails. The calculation of this imped-
ance is therefore hardly possible and in all cases its value must be detflt^
mined by experience.
TBATA OF STltBBT RAU.WAY CXRCinVS.
The following tests are condensed from an article by A. B. Herricli In Um
Street MailvHxy Journal^ April, 1899. i
The following instruments will be required :
A barrel water rheostat to take say 100 amperes.
A voltmeter reading to 600 volts.
A voltmeter reading to 126 volts.
An ammeter reading to say 160 amperes.
A pole long enough to reach the trolley wire, with a wire running along it
having a hook to make contact.
Use one generator at the station, and have the attendant keep pressure
constant.
Teet for Drop
Itoetataaco ta OrorlMad KJtai^
of instruments is run to the end
desired to test, where a Une circuit-
The car containing the above equipment
of the section of conductor which It is dcf
breaker divides the sections.
The instruments are then connected as shown in Fig. 168.
It is clear now that if the switch Q be olceed, current will flow throu^
the rheostat and be measured by the ammeter. We now have the trolley
and feeder B for a pressure wire back to the station, and the reading of
voltmeter G therefore gives the drop between the station and the point A
in the feeder and trollev carrying the load. Voltmeter D shows tae drop
across the rheostat ; and if the sum of readings 0 and D be deducted from the
station pressure, the difference will be the drop in the ground return.
zSi
The lUtloii preMura can ha t»kt
dovn to F H ihowu br the dotted II
The drt^ on A and lu i
X* Road tke firoud B*t
K Drop Directly.
CKwn IhaiUtloniwltcb on tbtit feeder that Ig Twine dm
uul ernubd the feeder to the ground biu through a fuse
,-■- — .^.i.. i„..^«.„b ^ ihown In (belolloi "
ring cat; then when the
Alo^read on voltmeter
-p
3;
r
800
ELECTRIC RAILWAYS.
>• lietevBtlBA livep »t 1B«< •f Ume*
F6r use on doable-track lines only, nnleea a preuore wire can be nm to
the end of line from the last line eirooit-breaker.
Break all cross connections from feeder to troUey-wire for one track, as
at n ; connect this idle trolley to the next one back toward the station, as
at 0, then make the tests as in the two methods described aboTe, oonneotlogia
being shown in the following cut.
FEEDER
Fia.165.
IHYlaiom of M^tm
M of «^..«^ «.«.^».,
rr«mt tlirovr>> Ralb, Wfi
or C(oa Ptpoa,
The cnt below shows the connections for this test as ^plied to a sln^
track, or to one track of a double-track road.
Oround the feeder A at the station, or rather connect it to the ground bos
through a fuse. Then connect the track at G to A by the pole £ through
the ammeter M. The drop between points F and D will be the drop through
the rail circuit between G and D, due to the current flowing.
If connection be made to a hydrant, or other water oonneotion, and to a
gas-pipe, as at X, still retaining the rail connection at C, more ourrent will
Vta, 166.
It !■ Dot 00DUD«rd»llT pnoUekbla (o
Joint*. H •Dch roitalanee li gmmll vndei
ooDdiliodi TKTT to mooh H to wsvaut ■
Til* nalaUDoe of rail Joint! Ii a
nUl lUMlt, uid (li«re w* nBDMnnu uuuiiii
Dearljr •11 being buad upon tbm pIin(^lple of (ha vhw
reafstmn«e of the nUI Joint bdng balMuwd agKiiut a ■eotioD ol (h
the rollowlns diagtam.
Fra. 167. Diapam of Method of Taiting Ball Jolnta.
retlabli
point In the mtd-
dlaof the aoala, 1« the handleet Inatrnmeiit tor nmking fiuaetasU. The
point* ft and eueflieil tuoallT at a dlBtanoe of 12 inch« apart, the pointa
[* than moved aloiig the rail nntll thare la no deflection ot the needle vhen
both dritehea are eloied. The reelitanM ot the joint or the portion batvean
the polnta b and c Ig to that of the length, x. loieniely ai the lenfrtb ot the
tonnarlato that of the latter, all being In tannaot the length ot rail, or,
z = dUtanoe in Inohea between polnti a i
v = dlatanoe between the polnta c and b.
V = realatanoa of Joint in lemu of length
802
ELECTRIC RAILWAYS.
and if X = 36 inches and y = 12 inohet,
tbep
36
V = T^ = 3 times its length in rail.
Another scheme for testing rail joints is pointed out hy W. N. Walmaley
i& the ** Electrical Engineer j*' December 23« 1897.
In the following cut, the instrument is a specially designed, double miUi<
)ltmeter, both pointers having the same axis, and indicating on the sjune
voltmeter
scale.
OOUBLC
IMVIVOLTMBTifl
WALMSLEVS RAlk TESTER
FlO. 158.
The points ab are at a fixed distance <f , the point o being morable along
the rail. Points a and b are set on the rail astride the joint, as shown ; the
point c is then moved along the rail until the pointers on the instroment
coincide, indicating the same drop. Then the resistance of x' is the same
as d, in terms of the size of rail used.
Harold P. Brown has devised an instrument for testing rail joints with
littlepreparation. It consists of two specially shielded mllli-ToItmeters of
the Weston Company's make, put up in a substantial irooden ease, the top
of which is made up in part ox two folding leas which, when unfokUtd, oover
six feet of rail. These legs form one length, which is divided by slots into
two lenrths, one of one foot, the other five feet long. The instnunent is
placed alonffside the track in such position that the leg rests on the rail, and
the joint to DC tested is between the ends of the shorter branch or leg, while
five feet of clear rail are included between the ends of the longer leg.
The instrument terminals are connected to small horseshoe magnets, that
fit into the slots in each leg, and when rested on the rail always make the
same pressure of contact, the poles beins amalgamated and coated witii a
ppeclai soft amalgam « called Eaison Flexible Solder.
With the five feet of rail as a shunt, the instrument will read to IISOO am-
peres.
There are several separate resistance coils and binding-posts supplied for
different sizes of rail in common use, so that the dial of the milU-yoltmettf
needs but one scale.
The second milll-voltmeter measures the drop around the one foot of
joint, and has coils so arranged to permit of reading .15, 1.5, 15. Tolte.
A reading of the current value is taken from the five feet of rail, and a
simultaneous reading of the drop across the Joint and one foot of nil is also
made. The resistance of the latter is then found by ohm's law.
TESTING RAIL BONDS.
803
FlO. 159. Brown's Bail-bond Tasting Instrument.
Atreet Jiallwaj Mot«r T«s«lB|r-
Baxn test for efficiency : —
Pnt a doable-flange pnlley on the car axle for the application of a prony
brake, pour water inside the pulley to keep it oool., Use common platform
•oale, as shown in cut.
y
Pio. 100.
Then let D = distance from center of axle to point on scales in feet,
meMured horlsontally.
ir = 3.1418,
R = revolutions per minute,
E = voltage at motor,
/^ amperes at motor,
T= force applied to balance scales, in pounds.
2wDRT
B.H.P. at 600 volte =
EI
Then B. H. P. =
33,000
600'
746
600 /
746
33,000
= E.H J*, supplied to motor.
= E.H.P. supplied to motor at 600 volte.
,^ ^ - ^ B.H.P. B.H J». at 600 volte
Efllciency of motor = -^^^^^ x e.h.P. at eOQ-^SiTs'
PaU
d Sfliclency Xeat IVitlioiit li«moTlBc
llIot«r IVom Car.
Big up lever as shown in cut, being sure the fulcrum A in strong enough
to stand the pull. Poste, as shown, make good fulcrum ; have turn buckle
# for taking up any weakness.
ELECTRIC RAILWAYS.
804
TeatlM Drop !■ MAllwaj Ctimlte. — Fbr this test
be made of any oar that is in good order, and it ahould be carried out
after the last oar is in the barn, and the track is dear. Run the car OTer
the line starting from the point nearest the power house, making the test
at any points that may be selected. The following cut No. 101 sbowe the
arrangement of instruments.
Amnmmr.
Fig. 161.
B "■ drop a to b without load, and in dear dry weather this should be
same as at the switohboard. In wet weather or with poor insu-
lation the drop without load may be considerable.
El -" drop a to 6 talcen with the brakes set and the controller on the
first notch.
/ ■■ amperes of current under conditions ^i.
E — Bx^ e ^ drop in circuit due to current /.
R '^ -J ^ resistance of entire drcuit of trolley wire; feeders, and rail
returns.
Rx ~ resistance of feeders and trolley wire as calculated from
known dimensions.
R — Rx'' resistance ol the return oirouit.
Fia. 162.
Let D = diameter of car wheel in feet.
V = 3.1416,
T= force on scale in pounds,
L = length of long arm of lerer,
L, = length of short arm of leveri
It == rerolutions per minute.
Place a jack-screw under each side of the car, and lift the body until there
is only friction enough between wheels and rail to keep the speed of rerolu-
tions down to the normal rate.
Then
and
Draw-bar pull = T -_ - 1
B.H.P. =
T-^DwR
33,000
FAULTS AND REMEDIES. 805
and the eflloienoy ii the same m befbre,
1.6. „ -- p = effieiency.
Mr. A. B. Herrick has derlsed a testing-board for street-railway repair
shopfl that will greatly assist in making all Inspection tests, and which is
described in the '* Street Bailway Journal " zor January, 1898, pages 11
and 13.
Car ITfll Mot Btmvtz «
a. Tom on lamps ; if they bum, trolley and ground wires are all right
and current is on line.
6. If lights die down when controller is thrown on. trouble may be poor
eontact between rails and wheels, or oar may be on ** dead " track.
e. If oar works all right with one controller, fault may be open circuit, or
poor contact in the other. Throw current off at canopy, or pull down the
trolley and examine the controller.
d. See that both motor cut-outs are in place.
e. Fuse may be blown : throw canopy switch and replace.
/. See that motor brushes are in place and intact, and make good eontact.
47. Gar may be standing on " dead " or dirty rail ; in either case connect
wheels to next rail by wire. It is better to open canopy switch while eon-
necting wire to wheels, or a shook niay be felt.
A. Ice on trolley wheel or wire will prerent starting.
•p«rblngr ttt Contmatator Bmslies:
a. Brushes may be too loose ; tighten pressure spring.
b. Brushes may be badly burned or broken, and therefore make poor con-
tact on the commutator. Replace brushes with new set, and sandpaper
commutator surface smooth.
e. Brushes may be welded to holder, and thus not work freely on commu-
tator surface.
d, Ck>mmutator may be badly worn and need renewing.
e. Ck>mmutator may hare a flat bar, or one projecting aboye the general
surface ; oommutator must then be turned true in lathe.
y. Dirt or oil on commutator may produce sparking ; clean well.
S*lssas« at the commutator may be produced bv : —
a. Broken lead wire or coil, producing a greenish flame, and burning two
bars usually diametrically opposite each other. If left too long the two
bars will be badly burned, as will also the insulation between.
Temporary relief can be had by putting a Jumper of solder or of small
wire across the burned bar, connecting the two adjacent bars to each other ;
one jumper is enough.
b. A short-circuited fleld coil, or a field coil improperly connected, will
produce flare at commutator. Short-circuited coll can oe found by yolt-
meter test across terminals showing drop in coil. Wrong connection can be
detected by pocket compass.
^
it KAns|M sometimes bum out or break. Replace with
new ones. If they do not bum when switch is on,
a. Examine each for broken fllament.
b. Bzamlne for poor contact in socket.
c. Bxamhie switch for poor contact or broken blades.
d. Examine each put of circuit, switches, line, and sockets with magneto,
which will locate opening. The wire may be broken at ground or trolley
connections.
SrakM 1*811 t9 Operate:
In great emergmicy only, throw controller handle to off^ ro^one reyersing-
■witch, and turn controller handle to first or second notch.
806
ELECTEIC RAILWAYS.
In sliding down srades, or when there is time, proceed as follows :
a. Throw controller handle to off point.
b. Throw canopy switch off.
e. Reverse reversing-switch.
d. Throw controller handle around to last notch. Both methods •»«
more or less strain on the motors, but the second Is somewhat less so than
the first.
C^roands: Either on field or armature coils will nearly alwavs blow
fuse ; It can then be tested out. ' ^
Backlwz When running along smoothly, a car will sometimes com-
m^ce Jerky, bucking motions, and should be thoroughly examined at onoe.
U may be due to a ground of field or armature that may short-circuit one or
m other, either fully or intermittently. Ininred motor may usually b«
located by smell of burning shellac, and can be cut out at the eontroUer
and the car run in with the good motor.
Mud and water splashing on commuUtor will sometimes produce bucUmr.
and oft«D a piece of wire caught np from the track may do the same.
n[tac<illwii«««a ITote.
Experiments show that four arresters per mile of trolley wire are plenty foi
safety.
Green wooden poles should not be painted for at least a year after they
are set. as the paint will peal ofiF and not give good results.
Loose ornamental joint caps frequently used on iron or steel poles collect
moisture and rust out the pole.
irirlngr DlagrvAma for UgrltMar Clrc«ite •« Atreet Cavb.
ivon«r
rraller
-2*i*l2-j^
FiQ 163. TMairramfor two Circuits Fio. 164. Diagram of Wirinc to
Headli/^hts. Platform Lights and permit use (tf 32-p. Headlight.
Sign Lights Interchangeable.
C
c£
Thm Point
Swltoh
^
B«MLIi|ht
BM4U(hl
^
^ 17
Fio. 165. Diagram of Wiring where Fia. 166. Same as above but three-
Headlights are placed on Hoods. poiut Switch located on TroUeor
End of Car.
^
SPECIAIi METHODS OF OIBTUIBUTION.
807
L
^
iV^i
^
1
8%BLI|h«
Ughtl
B
AmPsteft
BvHoh
5
■*"
iflMdJUilU
Flo. 167. DUcram of Wiring for Fio. 168. Same a* above exoM>t
five-light Circuit with four-point Uuee-point Switch.
Switch for Headlights and Pkt- ^^
form Li^ta.
BptOml Mvtiioda •f IMatrlUstl^s.
For cases requiring excessively large currents carried a considerable dis-
tance, or for ordinary currents carried excesslye distances. It Is usually
economy to adopt some special method ; atid among those nKwt commonly
mentioned are : the three- wire system, the booster system, the substation
system.
ftyatem. This system, patented some time ago by the
General Electric €!ompany, has been seldom used, and where used has met
with little success, owing to the difficulty met in keeping the system bal-
anced.
The diagram below will assist in making the method plain. Two 600-yolt
generators are used, as in the lighting system of the same type. The rail
return is used as the neutral conductor; and if both trolley wires could be
made to carry the same loads, and to remain balanced, then the rail return
THREE WIRE SYSTEM
Fia.169. Three-Wire System.
would carry no current, and no trouble would occur from electrolysis. The
orerhead conductors could also be very much smaller, as currents would
be halved, and the full voltage would be practically 1000.
A balanced three-wir« system has been proposed and is in limited use
abroad in which the car carries two trolley poles, making contact with both
trolley wires. The motor equipment is in duplicate, thus each set of motors
is fed from 600 volts making the current through the return practicaUy sero,
and the whole equipment forming a balanced three-wire system in itself.
This svstem is the only practical tnree-wire system and ^offers some advan-
taMs for transmitting large amounts of power over oonsiderable distances.
Tlie Booat«r Sjratom. — Where current must be conveyed a long
distance, say five to ten miles, and be delivered at 500 volts, It is hardly
good economy to install copper enough to prevent the drop ; and if the volt-
808
ELECTBIC RAILWAYS.
Me of the generator be raised suf&clently to delirer the required Toltage,
tne ▼arlations due to change of load will be prohibitive.
In each caaes a ** booster " can be connected in series vith the feeder,
and automatically keep the pressure at the required point, as long as the
generator delivers the normal pressure.
The " booster " is nothing more than a series>wound dynamo, eonneoted
so that all the current of the feeder to which it is attached flows throng
both field and armature coils, and the voltage produced at the armature
terminals is added to that of the line, and as the voitaffe so produced Is in
proportion to the current flowing, it will be seen that ttie pressure will rias
and fall with the current. This is now used in many Instances, both in
lighting and for railway feeders, and especially in feeding storage batteries,
and has met with entire svocess. The following out is a diagram of the
connections.
f V01«l
OVnHEAO BCTUMN
BOOSTER SYeXDI
FlO. 170.
r. — Maior Cardew, Electrioal Engineer for
the Board of Trade, some time ago devised a method of overcoming exces-
sive drop in track return circuits oy the use of insulated return feeders, in
series with which he placed a booster.
The booster draws current back toward the station, adding its E.M.F. to
that in the feeder. Gardew used a motor generator, the series field of
which was separately excited by the outgoing feeder for the same section of
road. Thus the volts ** boostea " were in direct proportion to the current
fiowlng. H. F. Parshall, in adopting the return feeder booster for some of
his work in England, used a generator in place of the motor generator of
Major Cardew, exciting the field by the current flowing out on the trolley
feeder, thus producing volts In the armature in proportion to the eurrent
flowing. The following diagram shows Parshairs arrangement.
TfWLLXI
>^ (SEPARATELY EXOTTEO)
y4- ^AENEnrraa i
BUS BASS A7 STAXna
aENERATOKS
Fig. 171. Modification of Major Cardew's System of Track Return
Booster for Preventing Excessive Drop in Ball Return Circuits.
ELECTRIC RAILWAY BOOSTER CALCX7LATI0NS. 809
■Icctrlc Iftailwaj ]i«o«tor CaUcoIatloMs.
(H. 8. Pvtnam.)
The following method of oaloulatins the else and characteristios of eleetric
railway boostecB, and the graphic representation of the reeulto will be found
useful.
A\ A^t A*. A\ etc., — load in amperes at various points along the line.
These loads should be taken from schedule, and should ordinarily represent
an average maximum condition.
R^, R*t R*, R\ etc., — feeder resistanoe (including trolleys) to the corre-
sponding load points.
1 « drop in volts to the point at which it is proposed to feed into the
system with the booeter.
V — allowable volts drop in feeder system with the booster in cinniit.
/ — amperes in booster.
S « volts boost.
g
p — 7- — ratio of volts boost to amx)eres boosted.
Rb «" resistanoe of booster feeder.
R — resistance of feeder system to point selected for the booster feed.
Then assuming that all the load beyond the point at which it is proposed
that the booster should feed into the system £b concentrated at the latter
point,
2 - A» «> + A«il» + A*R*, etc. — A» «.
' R •
V
J»-j +p.
E" I Xp.
V
p-Rb -f-
These equations give the necessary data to determine the required sise
and raUo of the booeter and its feeder. In case it is desired to install a
aecative booster, the same method is followed.
In case the load is uniformly distributed over the line, or is assumed as
distoibuted in that manner, the voltage drop at any desired point on the
line is found from the equation:
- (2 L - d + 1) d/Jg
X- 2 •
in which L — total length of line in feet.
d — distance to point selected.
/ M amperes per foot.
R — resistance of feeder system per foot.
If desired these units can be expressed in 1000 feet or miles or any other
unit of distance.
When the drop to the end of the line is desired, this equation becomes:
2
J
5
810 ELECTRiC RAILWAYS.
It ij oftsn deiirabJe to npremnt Uum oalculatkins cniDhioKlly. Bpodal
cua sn ebown m f^. IT2 173 nnd ITl. in which the potsntul dia<na
u flhown for differcDt cOQditJdna and schAduleH. In the prfipKfKtkiD cf
th^« diApAiOA it will tw found cunVBoiAnt to plot the loneduls oxfed
feederandretumruistuioeioiilliesame sheet. In Fis. 17Zit iiM(tntbM>
nfgative booateris not required though one la IncLudM. Fii. 173 iihowm >
■yiWmia which ■ booster la lued at either end. Fit. 174illiutrateiiidilhraat
and more Hvers operating condition than ahown m Fis. 173.
Kdvln'e L>« cat) be appUedto the boogterdiitributian m vail aatootkar
matboda of diatrfbution. In moat caaea, however, it wilJ be found that Um
Toltaee t»<iuifemen[» will rovem. Thn quegtioo u to whether a booilar.
more feeder copper or a aui>-e(«tJon ahall be employed. i> one which muat
be determined from the annual eha»a asainat the mveetnient and the eoat
of the power Lo3t in each method. ^ calculaCins the coat of the bower loat.
the load factor muat be conaidered.
In selectioK a booeter care muat b« exertnaed that ite overload eapadtv
shall be sufficient to take care of the niuximum operalinc condition whien
oocaoionaUy arisee in any ayalem where IxKntcra are likely (o be empkayed,
namely, when all the cars are accelerating at once. Ap auoh oecaaiona may
be rare, it ia only necenaary that rhe voltage ahall be maintained above tb*
employed, that the booster motor ahall carry auch overload, and that tha
maeluDea shall properly oomtnulate at the ovarioad eutretit.
By varying the value of "p" (he ratio of the vol ta of boost to the ampana
booatfld, the si» of the booaiw feeder and the amoant of power lost in th*
booeter ayatem is changed. By Kelvin'aLawtheannualcharffesoD theboo^
tar feeder and booaler should equal the annual mat ot the powar kwt in Uw
booster ayat«n .
ELECTRIC RAILWAY BOOSTER CALCULATIONS. 811
ELECTRIC RAILWAY BOCBTEB CALCULATIONS, 813
SB mlkmbl* in Iha voltsfS sbBnurtcrinio of i
datanniaa the HBauiit ol nuuriil raqoirad
kOtiul volt&CB eluradtari»tiB id eommATci&t ~
■-'-- "— • •. whioh Bt panlftl bad iriU
i
Bommerci&I Hriea bogatm ia not a itnushl
IftI bad iriU b« kbovs tba th«oreti«I l[ne u
, - Aoiain. The unount of vuutiati fnnn tha
nndly aSeol
Uih, th*v)
' )«. tba voltaca oliarmatenitio* cu b« madii
ItniahC Una; bat. obvioiuly, ■ DuotuM (o
a boMtar having a valtai* chaimctenitio
i^t Una. Theae FacU are partioularly jm-
ice booit«n an used, aa may be asen (roin llw
iportADt faetoT
'eommercial a
, ^ Jal bad aitl b
■bows in tlta aecnmpanyinc diamjn. The
•Uaicht line ia prindpally aSeolM by the uCnratioa ol the loacnatie sinuit; ,' A
if tlia ■aluiBtion ia hish, tha varialioD of the voltage ehanoMriatit will be MM
cnat' By inareaaiiiB the amount of iron in ttie macnetio fnine and there- t ■
lore keeping Cha taturation lov. tha voltaca obaraateHitioa can b« mada VI
(o mora naariy approilmate a atcaiBhC line; bat. obvioiuly, a maohine ao ^^
deaijcned ia mora tioatiy titan a boMtar havinc a valtasa chaimcCeriitio
depvtinc furtiiar from a itrti^t line. Tlieae FacU are partioularly im-
portant in eaaea where high voltan bocMt«ri are used, aa ouy be aeen Itum iIm
Qlowing eumiJe:
In the aosoompanylns diagnuu of a 200-kilowatt, 40O-volC booatar. tlia
potential at half load k 240 volta, that ia. 10 volla, or 10 par omt (i< tha full
Fio. 17S. Charaatoiatloa at a 200-Kw. 40O-Volt Boorter.
load voltage. hi|ber than a theoretio^ atraiiht line charac^terietic. I
itral^t line muat be Iiei>l within reasonable linuU.
Uoleaa otherwiae specified, the volta^ charaeU
Mrifv booatars of different potentials should not exc
at partial ourrvnt load and at conatant speed:
FnU Load Voltage, of Booaten.
SSSiraa'-
IeIIs'
lOperoant
I giimniiKlioc air, pn>vid«d
■y eoavertcn iiaa led to mtttiy ilnilkr ds^cna of
ry to inslall Ih ■" " ' "" - '•
111 170 "hnw ft
I in reality b coiniileta supply i
Mliva devicn for both talch-U
a iDslBll Ihe rotarica in buitdinH dnicnad tor
■ 'n plui and elerb-
aUa-STATION SYSTEM.
SSsi
tin
ilii
If
ELECTBIC RAILWAYS.
natiuiiil 600 Toltidlnet-ourraDt siroaita. Tha i
m in Fis. 180.
a FiK- iBl is Bbciwa ■ aiom saotian of oaa of tl
eloped for Ihe United Rwlnys uid ElKtrio
Mr, i.. E. Utillvdl. This itaUon hu ■□ umu
oanuir id lead.
D daiznini gub-gUtioag. their equipment ahoul
■ of (E* Duximum losd of tb« gtalioog, vhile ■ MatnJ p
nLtiny tlifotich lobuice m^y be deoisned to tAka the m'
PLAN
Pio. ITS. Rotuy CoDvarto' But>«t«tioii.
1
aCB-BTATlON 8C9TXU. 817
i
i
Fio. m. itoUuT CimvwMr Sut^Mtion.
r
8J8 BLECTHIC KAILWAYS.
5
Fio. 180. DUcnm of Conncstiona far PropoMd Rotuy
1
SUB-STATION SYSTIill.
819
(
Fio. 181. CrooB seetion of typical large 8ub-«tation (1007) 12,0(XV-kilowatt
13,00O>volt8 alternating cuirenL 575-volt8 direct current.
L. B. Stillwell, Engineer.
Sii1»«Stetl4nM. — Many roads have a heavy traffic on
certain lines for a portion ol the year only, thus making it hardly feasible to
expend a large sum in a permanent sub-etation. For such cases, the porta-
ble eubnitation has been designed, consisting of a box car containing step-
down transfonners, rotary converter and all necessary protecting devices.
Sudi a sub-station can be run out on any line having a transmission system
oofxnected up, and put into service in a very short time. It thwefore
forme a reserve sub-etation. A i;>lan, elevation and diagram of connection,
of a tsrpioal portable sub-station is shown in Fig. 182.
A portable sub-station having as high as 1000-kilo watts capacity is in
use, see Street RaUway Journal, November 4, 1905 and June 23. 1906.
1
THIRD RAIL SYSTEMS. 821
(By F. R, SlaUr.)
For o«rtaiii cIiumm of eleotrio railwmjrg. cuoh m elevBt«d, interurban and
undersround, a steel conductor inaukted from and alongaide the tniok.
commonly ealled the third rail, ia much uaed in place of the copper over^
head trolley wire.
This oooduotor ia eaaily inatalled. cheaply midntained. presenta a laxv*
aoiface area for oonduotin^ and oollectinc the current, and it, therefore,
particularly suitable for high speed and neayy service. With eosts cal-
culated on the basis of equal conductivity in rail and trolley wire, the
third rail is the che^Mr. except where the necessary troUesr wire would be
of oonaderable lees conductivity than would be obtained with the smallest
■as of steel rail that would ordinarily be used. Even in such cases the
fewer ooet of maintenance, together with the advantage of adaptability
(partieularlv in the case of terminals, yards and very heavy high q^eed
service), wiu frequently offset the higher first cost of the third rail and
make it the praferable means of conducting the current from the power
station to the car motor.
With the coming of the heavy Ughnvpeed service of the past fow yean,
the resistance of standard "T*^ raus has been found to be so high, that
rails ci higher spedfio conductivity were sought, and specifications have
been drawn, usually based on the fact that the conductivity oi a metal is
generally direcUy proportionate to its purity.
JtMUteace of WtaMm witti Vavylvv Coaspoaltloa. — Mr.
J. A. Oapp. of Sohaneotady, conducted a series of tests of steel for
eieetric conductivity. He BByn in part: "In most cases the purity of the
iron specified for sooh rails has been so high, that not only was it difficult
to obtain, but the iron was also corresponmnKly high in price. One of the
factors governing the choice between a third rail and a trolley wire is the
lelativo price of steel and copper, aUowance being made for the difference
in conductivity. Hence a balance must be struck between high conduo-
tivity (vriiich IS equivalent to saying a liigh degree of purity or freedom
from toe usual metalloids assooiatea with ut>n) and the cost of producing
the steel of the composition necessary for the conductivity required.
"Table XVII below states the electrical resistance and the chemical com-
position of 47 samples of steel, and Table XVIII ■mibtf data on 7 samples
of wrought or refined iron:
ELECmiC RAILWAYS.
S5!:ssi|?5S§l=ii=i=SsS3iJ2
S;
li
R!s^-l".S^2S23Sj^2^^2Ei^^^!S22^^
&l^lfelill5!^S!S2^life&!2S^l5^l;
824
ELECTRIC RAILWAYS.
!
I
U
•
I
I
i
i
a5
+
OQ
+
s
•
^
3
•
ii
A.
l!
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m
a
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•
■
«
• •
0
•
'3
^
r*
es to
1
^
>o
CO
o
s
Ji
»-« I-l
QQ
•
•
•
•
o
■
o. <=i
^
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1
Oi
OQ
s
•
s
•
•
•
■
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CD
-^
•^ Q
o;
CO
•
?
C4
•
•
%
1-t ^
1
•
i
1
•
•
r-l O
•
•
-i
to
u»
«D
n
t*
S «0
o
*
•
•
•
• ■
o'
1
1-
1^
•
B
• •
<D CD
1
il
1i
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CO
1-*
•
CO
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1
jS*
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e
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o^
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*-(
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1
RESISTANCE OF BTEEL.
825
vnpopdmaim in influ-
reBistivity tnia element
'A itiidy of tbft tablet ihowi that
the reeietance of eteele and that for lowest reristlvity
present in yery emaU quantity, much smaller than is usual in mer>
chant or stnietural steels. While all the other elements must be present
only in very small percentacWt ao great is the prqK>nderanoe ol the in-
fluence of manganese that tney may be tolerated in quantities whioh the
steel makers would consider reasonable, without unduly increasing the
»•
•f Steel. VsMlatiem with M»
(Cabbon raoM 0.17 to 0.23 Pan Cxnt.)
Sample
Nmnber.
Manganese.
Resistance.
Copper — 1.
Carbon.
P + S + fli.
Per Cent.
Percent.
Per Cent.
2
1.09
12.12
0.17
0.144
4
0.95
11.56
0.20
0.23
7
1.08
11.61
0.22
0.210
13
0.80
9.94
0.23
0.066
16
0.89
9.48
0.23
0.073
19
0.68
9.36
0.22
0.197
36
a48
8.36
0.188
0.17
26
0.66
8.22
0.22
0.058
37
0.67
8.16
0.192
0.068
31
0.48
7.96
0.23
0.057
36
0.40
7.73
0.23
0.028
86
0.37
7.71
0.19
0.15
43
0.21
7.38
0.19
0.099
44
0^
7J28
0.216
0.164
1
ef Meet. Variatlem with UKa
(Carbon fbom 0.27 to 0.33 Pbb Cknt.)
Sample
Blanganese.
Resistanoe.
Copper — 1.
Carbon.
P + 8 + 8L
Percent.
Per Cent.
Per Cent.
1
1J87
13.20
0.33
0.190
14
0.96
9.86
0.30
0.083
16
0.99
9.86
0.29
0.104
18
0.66
9.42
0.28
0.193
31
0.49
8.90
0.33
0.138
22
0.46
8.46
0.31
0.166
37
0.41
7.70
0.27
0.035
38
0.28
7.66
0.28
0.111
40
0.42
7.60
0.28
0.070
S26
BLECTRIG RAILWAYS.
Restotamce of fttoel. ITarlatton with Cm
(Manoansbb ntoif 0.15 to 0.28 Pbb Gent.)
Sample
NumMr.
Carbon.
Reostanoe.
Copper — 1.
P + S + fii.
PerOnt.
Per Cent.
Per Cent.
3
1.40
12.09
0.222
0.112
9
1.61
10.76
0.147
0.125
33
0.10
7.92
0.25
0.11
38
0.28
7.66
0.28
0.111
43
0.19
7.38
0.21
0.099
44 •
«r.216
'7.28'
•0.21'
' ' 0.»4
45
0.05
6.40
t
0.19
0.143
To determine the influeDce of carbon in the above table, thoee steels
have been sdected which have manganese constant at from 0.15 to 0.30
per cent, with carbon as the principal variable.
neatataace of 0«ool. VarlAtloit wltlt Gorboa.
(Mangansse Fsoiff 0.4 TD 0.49 Per Gent.)
Sample
Number.
Carbon.
Resistanee.
Copper ■■ 1.
Manganese.
P +S +8L
Per Cent.
Percent.
Percent.
21
0.33
8.90
0.49
0.138
22
0.31
8.46
0.45
0.166
23
0.25
8.42
0.41
0.17
24
0.144
8.42
0.46
0.17
25
0.188
8.36
0.48
0.17
28
0.16
8.06
0.48
0.144
30
0.14
8.02
0.41
0.109
31
0.23
7.95
0.48
0.057
35
0.23
7.73
0.49
0.028
37
0.27
7.70
0.41
0.035
39
0.07
7.66
0.40
0.163
40
0.28
7.60
0.42
0.070
42
0.15
7.40
0.45
0.044
loaiataaco of Atool. IbIImooco of Ci
(Rbsultb of M. Le Ch atelier.)
Resistance.
Composition.
Microhms.
Copper — 1.
C.
Mn.
SL
Per Cent.
Percent.
Per Cent.
10
5.78
0.06
0.13
0.05
12.5
7.22
0.20
0.15
0.08
14
8.10
0.49
0.24
0.05
16
9.25
0.84
0.24
0.13
18
10.40
1.21
0.21
0.11
18.4
10.64
1.40
0.14
0.09
19
11.00
1.61
0.13
0.08
RESISTANCE OF STEEL.
827
•W,
»r Steel, Varto«l
m Mid Hadfleld. Tei
lite
1»» C.
of
ReaiataaM;
Compoatton;
1
Sample
Mark.
Microhm*.
per
Copper— 1.
Carbon.
Manganeee.
Sil|oon>
Cu. CM.
'
Percent.
Percent.
Percent.
1392Q
19.1
11.19
1.23
0.14 .
0.12
1392L
17.6
10.31
1.09
0.32
0.17
1392A
17.9
10.49
0.85
0.32
0.17
1392B
17.2
10.07
0.84
0.18
0.20-
13921
16.7
9.78
0.83
0.25
0.06
1392H
16.1
9.43
0.78
0.10
0.10
1166A
13.4
7.85
0.14
0.06
lUBSmSTAirCK OF «KEBIi.
COMPZXiBD BT H. N. LaTBT.
C. GUATBR THAN .50%.
{
C.
.535
.568
.Ooo
.610
.740
.780
.830
.840
.840
.850
.900
1.000
1.090
1.210
1.230
1.250
1.400
1.400
1.610
1.610
.780
1.200
1.230
1.500
1.540
1.660
Mn.
.592
.608
.632
.650
.580
.100
.250
.180
.240
.320
.200
.580
.320
.210
.140
.620
.140
.222
.130
.147
3.810
7.000
13.000
15.25
18.50
11.50
Si.
.201
.204
.214
.220
.200
.100
.060
.200
.130
.170
Tr.
.490
.170
.110
.120
.460
.090
.082
.080
.092
.630
.630
.630
.630
.630
.630
P.
s.
R.
CU.-1
.051
.053
.056
.062
.043
• ■
• •
.059
.061
.065
.071
.036
• ■ •
11.30
11.40
11.50
12.90
11.40
8.50
8.87
9.36
9.25
9.55
9.78
13.00
10.10
9.25
10.20
13.70
10.64
10.76
11.00
10.76
25.70
32.40
37.10
38.55
40.10
35.80
.040'
.030*
m ■
.Old
.015
.018
'.0*18
•
• • •
Authority.
Parshall
G. £.Co.
Barrett
Chateher
Barrett
G. E. Co.
Barrett
Chatetier
Barrett
M
Chatelier
Q. £. Co.
Chatelier
G. E. Co.
Barrett
Remarks.
TRaa.
««
M
Bar.
M
u
Bar.
Bar.
Bar.
•«
Bar.
BLECTBIC BAILWATS.
c.
Ud.
8L
p.
8.
■x-i.
Authority.
Ranarlu.
.028
.030
s
.osa
s
.090
a
.100
i
.!»
.150
■1
•1
TV.
ss
ii
1
s
.200
1
i
i
.870
S
j)70
.140
S
i
■i
1
.ISO
Si
1
1
:oo4
.004
1
.014
■.080
i
i
;i
.130
.on
:o8o
i
■.cm'
s
Tf.
.070
:i
1
s
JMO
.033
1
1
.005
fl.oe
B.08
6.38
i
1
Is
i
11
7.8!
7-40
If
iL
sii
Burett
a, E. Co.
Bairttt.CE
Bamtt
G. E. Co.
a. E. Co.
Bamtt
G. E. Co.
Chat»H«T
g-po.
■'"do^-"-*^-
Bai, Swadid. iron.
Btaybolt iron.
Win, 3 U.H. diapL
Win,3M.H.diam.
Win,3U._lI.diam.
Bar.
Bar, n>ac. nl, irvL
TRaiU.E.*C.Ry.
^
RESISTANCE OF STEEL.
0. Lbsb Than .50%.
829
c.
Mn.
SL
P.
S.
R.
CU.-1
Authority.
Remarks.
.260
.830
.004
.053
.010
9.44
Q. £. Co.
.270
.410
.001
.024
.010
7.70
ft
«
JiSO
.280
.040
.027
.034
7.66
«*
J280
.420
.008
.022
.040
7.60
••
.280
.650
.050
.083
.060
9.42
••
.290
.990
.010
.084
.010
9.86
••
.300
.950
.010
.063
.010
9.86
4«
.310
.450
.026
.100
.040
8.46
M
.330
.490
.020
.068
.050
&90
•4
.360
.800
.047
.100
.040
11.51
M
.360
.870
.040
.080
.090
10.04
4«
TRaU.
.370
.730
.060
.090
.040
9.94
•«
41
.378
.650
.181
.040
.041
10.80
PanhaU
M
^10
.720
.110
.039
.041
10.56
Q. £. Co.
.430
.770
.066
.100
.040
11.51
•t
.446
.568
.188
.046
.044
11.10
ParahaU
TRail.
.400
.240
3.500
.050
.130
8.10
17.28
ChateUer
Barrett
Bar.
.080
• • •
• • •
.150
5.400
.130
■ • ■
• • •
19.65
i<
••
.150
15.400
.130
• • •
• • •
37.80
••
««
.160
10.100
.630
• • ■
• • •
37.10
•«
ti
.170
1.090
.004
.090
.050
12.12
G. E. Co.
TRaiL
.220
1.080
.060
.100
.050
11.51
M
•«
.240
1.000
13.000
5.15
.130
.130
.130
13.70
35.80
21.75
Barrett
•i
*4
Bar.
•«
.260
.320
■ • «
• • •
.330
1.27
.050
.09
.05
13.20
G. E. Co.
TRaiL
.360
4.00
4.75
2.25
.130
.130
.130
16.70
17.10
17.00
Barrett
««
Bar.
•4
*t
.360
.410
■ • •
• • •
(
For a aatisfaotory third rail, the lowest poorible resistance (from 6 to
6.5 times that of ct^per?) is not necessary: and the sreat cost of making
such extremely pure steel is not warranted. Assuming, then, that a rail made
from steel having a resistance not greater than eight times that of copper
(13.8 microhms at 20^ C.) would be desirable, the figures tabulated seem
to indicate that the following extreme composition would be permissible:
PWl CENT.
Carbon up to 0.2
Manganese up to 0.4
Phorohorus up to 0.06
Sulphur up to 0.06
Silicon up to 0.05
This composition, however, would be extreme, and any overstepping
of bounds nught result in too great resistance; therefore, for resistance
op to eight times that of copper, the specified analysis should be:
PKR CENT.
Oarfoon not to exceed 0.15
Manganese not to exceed 0.30
Phosphorus not to exceed 0.06
Sulphur not to exoeed 0.06
Silicon not to exceed 0.05
ELECTRIC BAILWAY8.
.. ^ ODB irhiuh lodd be mad* Mdr I" ■o)' omb-
e, mnd it ibould prBKOt no difficulty in rolling to & anape
(Fil. 183). In fut, itni ot (Us oompoatioo Iw
Man BUOMMfully rolled into shwuutbinuO.OM
ln„ ud wu For a looff tims a staodani product
of a ititfl (baet-milL.
Aiectionof a oi>nduoU>r-ruJ haa b«cn dwagnwi
by Mr. W. B. Potior, Chirf Engineer of theluD;
way Department iS the Gencni Eleolrio Co-
Hhich. vhen 2.5 in. wide by 4 in. high, will wn^
about (181b. Co the yard. This shape, n-hich la
abowa in Hg. 18S, may be «dly n>Ued in any
merchant-bar mill heavy enough to attempt no-
_ ouiin.. Tbe HuhattaD lUlway Company (Glsvated)
?wil;5^r ""1 *• Interborough Ramd Ttnoai Compotiy
HMiy m/ (Subiray). of New JorlTcity, both pur^Sefl
.S3. Ottm Beetioi
a New Cc ' '
L Deaigned
1 mllirtg waa aoalyaed. ■
FoUowing are the analyaea and Bpeci&caljoiu:
«.„.„.,.
Ir^aaoaonoK.
Spedfieation..
An»ly-a.
Analyrti.
Weight or rail . . .
AmoF ex»i aection
100 Iba.
'!"""■
:o3
t
:022
n.13%
8.98
1J89.000
75lba..
8.37
Si
.091
.055
Tia«
^x^tl'".^.
1.500.000
&50
1.100,000
IiOcaHOBorXblrdBall. — The loDstioi
enee to the track rails has been dilTereat iar ea<
.. Long Island, Ni — ■ " . ■
railroads have agreed upo
pasaage pf any of their r
of the third rail with refif~
h road using it. The Poin-
Interborough Rapid Tranal
will not interfere inth_tha
„. .HI k»ateil outflde
BD that its oenter Hne ahall b* 37 inehn
M uHXr face 3} Inehea above the bv of
^
THIRD RAIL INSULATORS.
831
lUUtATIFB X«0CATION OW TlUJlD RaIL
ON DiFFSiusirr lUxifWiLT Stbtsmb.
Gooeral Electric R«iIro*d, ScheQect»dy
Met. West Side Elevated, Chicago . . .
Lake Street Elevated. Chicago ....
South Side Elevated. Chicago .....
Northwestern Elevated. Chicago. . . .
Brooklyn Elevated, Brooklyn
Manhattan Elevated. New York . . .
Albany ft Hudson. New York ....
Boston Elevated, Boston
Aurora, Elgm A Chicago. Ill
Columbus, Buckeye Lake A Newark, Ohio
Columbus, London ft Springfield, Ohio .
B. ft O. R.R., Baltimore
N.Y.. N.H. ft H. R.R.. Connecticut . .
Central London, England
From Top of
Third Bail
to Top of
Track RaU.
From Track
Gauge Line
to Center of
ThiidRafl.
The requirements for a third ndl insulator are:
J a) That it shall have sufficient strength to carry the weight of the
; and not crush Uhder the vibration of passing trains.
(6) That its insulating body duill be made of a thoroughlv vitreous
material, practicallv impervious to heat and moisture, and having its
caq>oeed simace well gtaied.
(c) That its lelJStance shall, when wet over its entke surface, be 1 megohm
at kast.
(d) That it have a dtip edge between the rail and ground.
(e) That the portion upoif wlucn the rail rfleU.shaU allow free move-
ment of the ran, laterally and longitudinatty to allow for expansion and
contraction, and vertically to »llow Tor d^ression of ties during the passage
of trains.
CO That it must be capable of easy and quiiak renewal.
Those here illustrated show the two general types which have been most
widely used (Fig. 184 and Fig. 186). Fig. 184 consisU of a metal base
surrounded b^ an insulating body of vitreous material to which are clamped
the dips which hold the rail. Fig. 185 is practically the same, except
that in place of thct clips ehunping the insuuiting body there is a metal
em> setting over it, having ears which ma^ or may not be bent over the rail.
(
Fia. 184.
Fio. 185.
These insulators are usually placed 10 feet apart, except on sharp curves,
where U&ey are generally placed on 5-foot centers in order to keep the rail
up to gauge, to lulow for the expansion and contraction. The rail is usually
anchored at the two center insulators, any movement being taken up at
the joints where a sufficient distance has been left between raib for
832
ELECTRIC RAILWAYS.
the prnpooe. This is either done (1) by malring the portion of the faun-
later upon which the rail rests in such wa/ that it may be bolted to the
web of the rail, or (2) by making the portion of the insulator upon which
the rail rests with a lug that fits Into a slot punehed in the bottom flai^e
of theraiL
Where the shoe or ourrent eoUeetor leaves the third rail at the ends
on straight track and at the side at switches and crossovers, suitable in-
clines must be provided, because the shoes normally hang lower than the
top of the third rail. (See Fig. 186.)
Fig. 186.
■•11 Ali^c. — These shoes are of praotacally but two types
visv. the link shoe and the sUraer shoe.
The link shoe is shown in Fig. 187. and is attached to the coil spring seat
of the truck, and the shoe proper is suspended by two links from the yoke
Fio. 187. Link Shoe^ used on Manhattan Elevated Railway.
which is in turn bolted to castings on the shoe beam. This type of shoe ts
not entirely satisfactory because it has a tendency for the shoe to ride
on its nose when the speed is high, and does not permit of adequate pro*
tection of the rail from the weather.
THIRD RAIL IN8DI.ATOR8.
ir *bM abowD Id Ftg. IBS it
i
D
)
>
ELECTRIC KAILWAYS.
Mow Tcric <;«>nwl Tfel>«Ball. —
nil ia the joint InvntioD ut W. J. Wilsua aad Fntnk J, ^ns»,
^ Qot«d in tlw illuBtratioii, ia ■uppoited eraiy dvTflD f«et by iro
MiOD_ blooks by «fMul olunpL Theaa bl<
i»U ths upper part of
which hold the inaulMioD i>
wki, vfaieh
J mintcr-
Fn>. ISO. Ddtuls o[ Third RaU ConatniotioD, New York Centrkl R.R.
covered by wooden jiKp&thiiig, whiob ._ „p, . ,- r-
ti«eth<ir. At the joinU where the thinl rul is bonded, aai
tspi. the wooden Hiealhing Is
lima thut of copper,
■bove the tap of the
>ppliad in three parta and nuM
"■•' is bonded, end at the fewleT
xxmdfl per yard; is of ipw^
under nr conliuit flUrface is pLuced 2| in^c»
rail Md ite center in 4 feet Bl inchea (rom
traek» or 2 feet fi inohee from the (AdC* lio*
ie anchored. It weighs 70
Lpoeition; uid has a reslAtr
CONDUIT SYSTEMS OP ELECTRIC RAILWAYS. 835
I03LOIACT fl0VIMACT]» <?0»V OF OITB nXA
(W. B. POTTXB.)
0-Inch Channel Ibon Pbotbction.
fi26(y 754b. S" X 2Y eonduotor rail at $43 per ton (Od tons) . . S2.840.00
^8 Reoonatruoted granite insulators, olamps and lag screws
at 40 cents per set 211.00
352 Na 0000 QE 9" Form B bonds at 38 cents 134.00
$3,185.00
5280^ 31f-Ib. 6' channel iron guard for conductor rail at $45
S Br ton (27.71 tons) $1,248.00
ie^ron guard supports at 36 cents 286.00
176 Malleable-iron Bah plates and bolts at 25 cent 44.00
$1,578.00
Ai^iozimate labor for installaUon, including drilling rails and
channels 900.00
Total cost $5,663.00
8-Incr Channbl I«on PitOTBcnoN. '
6280* 75-Ib. 3' X 2Y conductor raU at $48 per ton (66 tons) . . $2,840.00
528 Reconstructed granite insulators, clamps and lag screws
at 40 cents per set 211.00
352 Na 0000 GE 9* Form B bonds at 38 cents 134.00
$3,185.00
5280' 4fr-Ib. 8* channel iron guard for rail at $45 per ton (42.24
tons) $1,900.00
792 ICalleable-iron guardr-rail supports at 36 cents 286.00
176 lialleable-iron fish plates and bolts at 25 oents .44.00
^J2i230.00
Approximate labor for installation, including drilling rails and
channels 900.00
Total cost $6315.00
8-Inch Wood PBoracnoN.
5280^ 75-lb. 3' X 2)^ conductor nil at $43 per ton (66 tons) . . $2,480.00
528 Reconstructed granite insulators, clamps and lag screws
at 40 cents per set 211.00
352 Nob 0000 QE 0* Form B bonds at 38 cents 134.00
$3,185.00
5280^ Ash plank li' X 8* at $48 (M board feet) in the rough,
5280 board feet $253.00
792 Malleable-iron guard-rail sxipports for wooden guard
plank at 39 cents 308.00
176 Malleable-iron fish plates and bolts at 25 cents 44.00
$605.00
Approximate labor for installation, including drilling rails . . . 750.00
Total cost $4,540.00
COiroiTIT SYftTflllKS OF BIACTSIC ItAUWAYA.
Previous to 1893 many^ patents were g^nted on conduit and other .sub-
mrfaoe systems of earrymg the conductors for electric railways, and hun-
dreds of experiments were carried on; but it has been only since that year
that e^talists have had the necessaiv courage to expend enough money
to make a really successfully operatmg road. The work was put into
the hands of competent mechanical engineers, who perfected and improved
the meehanioal details, and the electrical part of the problem was by that
nMSBs rendered very simple.
\
836 ELECTRIC RAILWAYS.
The Metropolitan Street Railway Company of New Tork, and the Metro*
poUtan Railroad Company of Washington, deeided, in im, that, hy build-
ing a conduit more nearly approaching oable oonstraetUm, the underground
electric system could be made a Boocees. The former contracted lor its
Lenox Avenue line, and the latter for its Ninth Street line. The New York
road was in operation by June, 1^95; the Washington rood by August of
the same year ; and they continue to run successf uUy. While modmcationa
have been made in some details since theee roads were started, yet the
present construction i« substantially the same. These roads were the first
to avoid the almost universal mistake of spending too little and baildins
unsubstantially where new enterprises are undertaken, ^e historyin
these particulars, of the development of overhead troUey and oonduit tobOm
is to-day repeating itself in the third-rail equipment of branch and local
steam roads.
The Metropolitan Railroad, in Washington, used yokes of cast iron placed
on concrete foundations, and carrying the track and slot rails Thealot
rails had deep inner flanges, with water lips to prevent drippixur on con-
ductors. The conductor rails were T bars 4 inches deep, 13 feet 6 inches
long, 6 Inches apart, and were suspended from double porcelain corrusated
insulators HUea with lead and mounted on cast-iron handholes. A sudinir
plow of soft cast iron collected thecurrent. During the first few months of
Its operation there were but few delays, mostly due to causes other than
electrical defects. Some trouble came from short-circuiting of plows which
was remedied by fuses on plow leads, and a water rheostat at the powei^
house. The flooding of conduits did not stop the road, althou^ the
leakage was 300 to «S60 amperes. Under such circumstances the voltiSe was
reduced from 600 to about 800. The average leakage on minus sideT when
tested with plus side flpx>unded. was one ampere over 6,600 insulators. The
positive side always showed higher insulation than the negative, possibly
*H2L *®,®^®'''°*y**® action causing deposits on the negative pole.
The Lenox Avenue line of the Metropolitan Street Railway was the first
permanently successful underground conduit line in the United States.
The oast-iron yokes were similar to those used on their oable lines, placed
6 feet apart. Manholes were 30 feet apart, with soapstone and sulphur ped-
estal Insulators located under each, carrying channel beam conductors,
making a metallic circiUt. At first the voltage was 360, but it was gradually
raised to 600. The pedestal support was afterwards abandoned, and sus-
pended insulators used every 16 feet, at handholes. At one time iron-tube
contact conductors were tried, but they proved unsatisfactory.
The details of track coni^truction for underground or sub-surface trolley
railroads are essentiallv of a special nature, and are determined in every
case by the local conditions and requirements. They belong to the civil en-
gineering class entirelv, and will not be treated here in any way other than
to show cuts of the yokes and general construction.
The requirements of the conduit for subsurface trolley conduetors are
flret, that it shall be perfectly drained, and second, that it be so desiimed
that the metallic conductors are out of reach from the surface, of any-
thing but the plow and its contacta. Another requisite is that the conductr
ing rails and their insulated supports shall be strong and easily reached for
repairs or improvement of insulation.
The conducting rails must be secured to their insulating supports In such
a manner as to provide for expansion and contraction. 'TOis can be done by
fastening the center of each section of bar solid to an insulated support at
that point, and then slotting the ends of the bar where they are supported
on insulators. The ends of the bars will be bonded in a manner somewhat
similar to the ordinary rail bonding.
The trolley circuit of the sub-surface railway differs from the ordinary
overhead trolley system in that while the latter has a single insulated con- '
ductor, and return is made by the regular running rails, the former has a
complete metallic circuit, local, and diMonnected m every way from track
return.
The contact rails must be treated like a double-trolley wlre,aad oalculatlom
for feeders and feeding in points can be made after the methods explained
for overhead circuits and feeders earlier in this chapter. Feeders and mains
are usually laid in underground conduits for this work, and the contact rails
may be kept continuous or may be divided into as many sections as the ser-
vice may demand, taps from the ipains or feeders being made to ttie oontaet
1
OOMDUIT SydXRHR OF EI^CTBIC BAILWA^S, 837 ^
CT^fcy
iiIHilltBii Kallroad, Wmshlnytmi.
.tag rill u
( Ib dimcuH to uj maoh rwknl-
> expeiuiTe U liuUlI that It su
CONDUIT SYSTEMS OF BIBCTBIC RAILWAYS.
Followliig in ■
■lectTlB oondnlta i . -, —
CampsDj, ol New York. Tba ajBtun of nllv
■lectTlB oondulta u d«>lxned uid bollt bTlE
Tho poroolaln iiuulator hei« iliown for mpportina ths ooDtact
ier7 BiibttuiUal In dwign aod CDDBtTontloD, uid by Its lookUon ■■
hole 1b flBflllT Tfluihed for deanlne, npAlrii uid replwwmaiit. Ths;.
also reaelTM careful attention, i^ tCoee now used «■ Jtuidnrd bj (he Met'
i
Studud Work, 1W7-SS.
r. Hew York. — Standud Work, 1
ELECTRIC RAILWAYS.
Fia. IfiT. PlsQ and ElBTAtlon of Plow Siupflntlon
Iroin Truck, Metropollun Street Railway, Neir
Tark.— Staudud Work, ll»7-l)g.
■VKFACn OOHTACT OR BI.KerKO-KAe»nO
The derslopment of aiirfacfl contuct iTiteniB bmn eron auller thu Ih«
hm of tba orwhwul-nDUar wira, uid nunr pslenta hiiTs bMO luaed on Ilia
WESTINQHOUSB SURFACE CONTACT SYSTEM. 841
flame. Moefe of these failed through ignoranoe of the reaulrements, and
timiditv of capital in taklns up a new device answers for others.
The westinghouse Electric and Manufacturing Company and the General
Kleotrio Company finally took the matter up, and being equipped with yast
experience ox the requirements, and the necessary engineering talent and
appturatiu, haye each deyeloped a system that is simple to a degree, and is
Bud to cost but half as much to install as the conduit system, and to offer
adyantages not known to that or other systems.
I ouote as follows from a bulletin issued by the Westinghouse Electric
and Manufacturing Company.
•onse Advamtefea of tlie Aystcns.
No poles, oyerhead wires, or troublesome switches are employed. The
streets, yards, and buildings are left free of all obstructions.
The facility with which freight cars can be drilled in yards and through
buildings, without turning the troUej wheneyer the directioa of a motor
oar or locomotiye is reyersed. and the absence of the necessity of guiding
the trolley through Ihe multiplicity of switches usually found in factory
yards and buildings, is of great adyantage. permitting, in fact, the use of
electric locomotlyes where otherwise electricity could not be used.
The only yisible parts of the system, when installed for street railway
work, are a row of switch boxes oetween the tracks, flush with the pave-
ment, and a double row of small contact buttons which prodect slightly
aboye the payement, and do not impede traffic in any way.
This system can be used in cities where the use of the oyerhead trolley is
not permitted, and if desired the continuation of the road in the suburbs
eiw DC operated by the cheaper overhead system. It would only be neces-
sary to have a trolley base and pole mounted on the car, the pole being
kept down when not in use.
"niere are no deep ezcayations to make. The system can be installed on
any road already in operation without tearing up the ties.
The cost is only about one-half that of a caole or open conduit road.
The insulation of all parts of the line, the switches, and the contact but-
tons is such that the possibility of grounds and short circuits is reduced to a
minimum.
The system is easy to install, simple in operation, and reliable under all
conditions of track and climate.
Finally, the system is absolutely safe. It is impossible for anyone on the
street to receive a shock, as all the contact buttons are " dead '* except-
ing those directly underneath the car.
!Be«iHlremeBta.
In devisiiig this system the following requirements of successful working
were carefully considered.
The insulation must be sufficient to prevent any abnormal leakage of
current.
The means for supplying the current to the car must be infallible.
The apparatus must be simple, so that inexperienced men may operate it
without difficulty.
The system must operate under various climatic conditions.
Finally, absolute safety must be assured.
This system includes the following elements.
First. Electro-magnetic switches, inclosed in moisture-proof iron cases.
Each switch is permanently conuected to the positive main or feeder which
Is laid parallel to the track.
Second* Cast-iron contact plates or buttons, two In each group, placed
between the rails and electrically connected to the switches. A separate
switch is provided for each group of buttons.
Third. The conductor forming the positive main or feeder. This is com-
pletely inclosed in wronght-iron pipe, and is connected to the varioas
switches.
842
ELECTRIC RAILWAYS.
Fourth. Metal oontact ihoM or ban, siupended from the car tmeka ;
two bars on each car.
Fifth, A small storai^e battery oarried npon the car.
The operation of the ayttem ia described as follows, and is illustrated by
cuts making plain the text.
RAIL
Fio. 100. Diagram of Switch Connections.
L D^STOflAOe BATTCRr'
C\J\A ~
IR PICK UP BAR
FiO. aOO. Diagram of Oar Oonneotlons.
Electro-magnetic switches, Xj, X., X.., inclosed In water-tight caalnga,
are installed at interrals of about 15 feet along the track to be operated.
Bach switch is prorlded with two windings, I and H, which are connected
by the wires li and M to two cast-iron contact buttons, 1 and 2, which are
mounted on suitable insulators and placed between the rails.
Each car to be operated on this system is provided with two spring-
mounted T steel contact bars, Q, and Q,, and a few cells of storage battery
in addition to the usual controllers and motors. The contact bars are
mounted at the same distance apart as the contact pins, 1 and 2, so that as
the cars advance along the track the bars will always be in contact with at
least one pair, as the length of the bar exceeds the distance between any
two pairs oy several feet.
Suppose a car is standing on the track over the switch X«, the contact
bars, Qi and Qt* b«^g then in connection with the buttons 1 and 2 reapeo-
tively. The iirst step is to *' pick up** the current, i.e., render the buttons
1 and 2 alive.
Switch A is first dosed : this completes the circuit from the stonue bat-
tery, D^ through the wlnng.B, contact shoe, Q., button 17o. 1, ana shunt
coil, H, to the ground. Tne current passing through H magnetizes the
core, S, which in turn attracts the armature. P, closins the switch and es-
tablishing connection between the BaO-Y main feeder K, and button No. 2.
through the contacts, JJ, coil I, and wiring N. Switch G is now closed and
switch A opened ; the switch X, is kept closed, however, by the eorrent
flowing from button No. 2 through bar Q„ connection T, resistance L, cmi-
neetion B, bar Q|, button No. 1, connection M, coll H to ground.
The car now proceeds on its way, current from the main panlng through
connection T, to the controller and motors. When the car naa advanced a
short distance the contact bars make connection with the pair of buttons
connected to switch X,. Current then passes from bar Q. through the
shunt coll of this switch. The operation described above is then repeated.
As soon as the bars leave the buttons 1 and 2. current eeases to past through
the coils I and H of switch X,, and this switch immediately opena by grar*
'WESTINQHOUBE 8DHPACE CONTACT SYSTEM. 843
1 ud huTulni. A» eooiiMtloii
d thionih iwllflh Z,, Ihsn wlU
Jiraiwti iwlleh oobUoM J J pane* through tha ■«rlBi ooU, I, boldlDg Iha
•Vltan flrmlj cloaed &nd preolndlng all poulblUtTot lU opaulng vUla e\a-
— . . .__ .t — ^ ^g ooutaoU, even ihonW the cironll Ihroogh ooll H
-.though the ftct ol "pioklug up thi euriant ''^require*
„„„ ..u. » ...dribs. It take* In pnatt«e only a few Hwondi.
Two separate awltghea, A and C. are Bhovn in Che dUgruni baC Inpnotlee
one ipectal twltoh of circular form U prOTided, and the Deceieary eombtna-
dona reqnired for "picking up thecarreut" are made by one rerolntion of
tha iwltch handle.
The battecy need only be smploTed to lift the flrit (witeb; for after that
ha* been doeed, the contact shoet bridge the daId Toltage orer from one *et
of pina to another, aa dcHiibed. thai oloilne the luoceeali* iwllohes. wllh-
ontlnrtharatteDtlon from the mototman. ^
The batteij la charged by leaiiug awltohn A and C eloaed at the Him*
Flg.aot ihowi the general arnutgamaDt of awlMh, bell, and pan. Th*
■wileb and tnagnat are mounted upon a marble ilab, which 1* teeored In
the ball tn mean* of lerew* to the boaaea, B B.
TheiwlMb magnet, U, la of the Iroit^lad type. It la aeeoied Co tha uppai
Via. 901. Section of Swlteh, Ball, and Pan.
■Idii of the marble baae,
" pick up " enrrsnC, and
'•%X.
Whan magnetlted the pole* attract an amistura atlachad to abridge piece,
.each end of whlah carriea a carbon dlak, N. B. R, are goldea for the bridge
lece, J. Directly abOTe each of the carbon diaka, N, b a atatlonart disk,
^ece, J. Directly abore each of the i
O, tnoauted upon a marble baae. One ui vuo uibk*, \i, ■■ uwin&uuuhij w.
neeied by meana of one of the eoDlact cups, Q„ aa eiplaleed later, to tl
. . ,... __. .,._ pQ,^^ through tha •aria* ooll and cup, Q,, (
844
ELECTRIC RAILWAYS.
TheiMui, G. i« provided with four bOMes, B, to sapport the rertieal split
pins, F, whioh ar« insolAted from the pan. These pins slide into recepta-
eles, G, on the switch base. The pins, F, are provided with connectors, I,
for the purpose of making connection with the several cables, H, whichpass
through the holes in the under side of the pan. The pan is completely filled
with i^ralllne after the connections are made, thus effectually keeping out
all moisture.
The object of the bell, A, and the pan, G, with the split pins, F, and the
cups, G, is to provide a ready means of examination of the switch without
disconnecting the wires. The bell can be lifted entirely free of the pan.
In replacing it, it is only necessary to see that a lug, T, on the side of the
cover, (Its into a slide, U, on the frame. When in this position the split
pins make connections with their corresponding cups, G.
The bell, A, is provided with lugs. L, to facilitate handling; and also a
double Up, W. Tne inner portion of this lip fits into and over the annular
groove, D, of pan G. This groove is filled with a heavy non-vaporizing oil.
The outer portion of lip, W, prevents water from entering the groove. The
object of the groove, D, and tne lip, W, is to make a waterproof Joint to pro-
tect the switch and cable terminals without the necessity of screw Joints or
gaskets. The bells are all tested with 25 pounds air pressure ; they may be
entirely submerged in several feet of water without affecting the operation
of the system.
Tlie Contact ^vttons are made of cast iron. They are about 4| inches
in diameter, and, when installed on paved streets, prolect about flve^ighths
of an inch above the pavement and offer no obstruction to traffic, lids Is
sufficiently high to enable the collector-bars to make contact, and at the
same time to entirely clear the pavement. For open-track Installations they
are substantially mounted in a combination unit as described below.
Fio. 202. Section of Combination Unit.
The boll and pan are entirely inclosed in a cast-iron switch-box. This box
and the contact buttons are made into a complete unit as shown in Fig. 101.
Each unit consists of three separate oastinffs. The cylindrical east-Iron
box, which incloses the switch, bell, and pan.Ts bolted into a recess provided
for that purpose in the bottom of the splder-lIke structure, which is a sep-
arate casting, consisting of box rim, receptacles for the button insulators,
and supporting arms. The removable lid is the third casting.
The Insulators, A, Flg.202,are made of a special composition, and are e^
roented Into the tapered cups, B, and supoorted by the iron plates, C. The
contact buttons, E, are mounted on top of these insulators and stand, when
installed, about one inch above the rail. - xv i tt *v
The four arms, O, are secured to the ties by means of the bosses, H, thos
reducing to a minimum the labor of leveliiig the boxes and avoiding the
necessity of special ties.
WESTINGHOU8E BURFACB CONTACT S
ib-boiw beinc iU ooDDooMd bf (hs iron pipe, m par oi
Fid. 203. Trkok Equipped tor Tnok Ratard Clieiiit.
Ho sdillttonsi wins tie naed to iDteroonneet th« ooUa oi •lonUcIa of ad-
JBcsDt iwltcbas.
Tk« CaaMct B«n we of >t«al, of ordlnu? T lectiou. TbsT are inp-
Krled from tlie car triuki b; two Qat steel ■prln^ and adjnatable llntt.
eae ban are Inellned at the endii >o that they may Teadlljr illde OT«r tbs
bottoDe and oier any ordtnary obalacle.
In eaae It !■ oonslderad b«t ni
Isted malug lor (bli pnrpoge maj bi
BOHMary to Inatall another row of cc
Via. 204. Track Equipped lor lniala(«dB«turnClTeult.
ki'ndr
pTBcedlng pa«ea appliea to the ■ntem
Fork. Modlflcatlnn* caa be maoe audi
•tn«t Bnllwaj' vr*rk.
The (oregDlng deecrlptlon spplie* to iDatslUt
(unpSTed),anil where It la unnecewiarT to make
(h« truki ei
placed between 'the ralli ud mounted on a light metal tie, aa ghown'in I^T
ELECTRIC RAILWATB.
ratloii of the irrtmn li ezuiar tha wme u In oMn.tn«k woA.
• wHroa nua fntin iha >.n.«~n. n«^., .1.. .1. .„ (£, Slrttoh-boiB«,
-n Ih« two traeka.
IDS. Seetlon of Track Equlppad for Street B^njStTTloe.
9 I* wuetlmda necaaMrr, (be button* ue plued Id a alnsle rtnr.
luythsl the "iilok-up'' ourtBOt ■bouldKa of tbe wmeToItu^
the msln cipnit. uuf eotuegnantlT tbe o»r-wliini ladiomledb
SMd, Iiutcwl of that ahoim In Fig. aoo.
Fio. ZOO. Diagram of CM-Wlrlnj.
ItoFls.aM, tbemethodof "plotilns np" tbe oomnt la m fol-
«h A li flnt cloasd ; Eh[g oomploCea the olroult ttom ■ alorace
tbrou(h a amall M»-Tolt molor-ceDetalor F, irhlob ImmadUtelT
: »oon a> It ia up to apeed, wbloL onlr reqolrea a few awundL
I closed ; ciurent tbsn oauea from F throogk tbe wlriu B to
>e Q, uid tben tbruugh the awltcb magnet, aa eiplaloed on pace
lea A and B are tben opened, thiu atopidiis tha motor-aanent^
d onl^ be lued to operate the lint ■wltcb. The luooeaal**
■e eloeed. aa deaotibed on page BO.
XmentofB hIgb-Toltige "plck-np" roav also be Daed adruh
tTo rove of buttons where the track la llabl« to be obatrooted
hanrallwajorilmllar
ivuMU, ouu ..«.j atHj irv uipuiOWU IIUIU QBCU DiaOT WnerOTBr
huabroalduglbemuplnloBeotloM which are each oonlTolledbi
tch. The lectlona ms; be made oi any deilied length to ault tbe
deetrlcal opei
! buttons are iiqm. i
der the control of tbi
aur moment should o
u or cmeslngi, when anTone Is liable to come I
:he length of ■ section nsT be reduced to M feet i
iratton of two-rail tiistallatlaiu Is tbe same as whe
lectlonal awltchea along tbe traeka ai
n, and Uie raUi mar be
G. E. CO. SURFACE CONTACT SYSTEM. 847
Fio.207. SoottoDKl Rkll luMllMIou.
conxACT KAii.YrAir.
yollowlnn la ■ dMorlpHon of the iurfies oontnot mtem, u devBloped by
the Oeneria Elsctrlo Comp&iiy, and pruUoal apptloitlaii of It hM b«aii
mule U Monte Cirlo, uid at the comptuiy'a Tork* a( HchenectKdj. The
deecrlpttim li tiom ■ report mida by w! B. f otter, CI. Eb%. ot tht kallvi;
DepBrtment. uid viitEen by Mr, 9. B. Btewdrt, Jt.
In theopermtlon arelectrEo cats, by th« cloeed cotidolt aarfaee piste con-
tut eyatem of the OsDentl Electrlo CompsDT, the current Is collected for
tbe motor service by means of two llffbC ateel ahoq carried nnder the csr,
making cuncaet with n teHts ot metsi pl>te«, Introduced >1cing the track
between the rolla, sntomstlcally snd altemslely energlied or ds-energlied
by meana ot awltches ^reaped at eonTenicnt plaeF« along tbe line ; the
melbnd of the swlteh oonCrol being anch (hatln the puisse of the csr, In
•Ither direction, It la ImpoailMe for any plate to becomeallTe except when
directly under the our body.
In ordlnsiT atreet ear practice, tbe contact platea are spaced approit-
mmtely ten feet apart, poeltlTe and negatlTe plates being ataggered. ai
ahowDlnFlg. aoa/»hlch admits ot but three plstea erer being coTeted at any
ptaMs of the same polarity.
In grouping the awltche* It la cnatomary to locatethem either Invsnlti
Mnutrnated baiireen or near Ihe tritckn, or Id acceaalbleplacm along the
fide of the street, the location and spacing of groi- ■■ •■ *
awltch« In each group being baeci' "■ — ' -'- *■'
style of Tanlt or otber recmlscle.
iwltch« In each group being baaed npon a cc^mparatlre cOHt bt
.^.^ -. ,.. ■•^ — T»«eptw;le,and the amoont ot wlrewltl
I and their cortenpondlngap ~
n generator feeder la carried to cHch vault or gronp,atii( auilllary
Dm It are distributed to eacb switch, the track raU b^ng utlUmi
^
848
ELECTRIC RAILWAYS.
TIm operatioii or performanoe of this lyBtem can be readil j traced out by
referenoe to Fig. 208. It will be Been that the current In its passage to the
motor from the positive generator conductor passes to contact A oi switch
No* 2 through the carbons on Its magnet armature (which has been lifted
by the energised ooilQ) to contact plates B and G, through the contact shoe
D to the controller and motor, coming out at contact shoe E to the contact
plate F, when It passes through the coil of the automatic switch G, ener-
gising it and returning by the track-rail H ; thus maintaining contact at
switch No. 2 armature carbons as long as the shoes remain on the contact
plates 0 and F. It should now be noted that oontact plate B is energiaed
MOTOR
MOTOR ''CI
Fio. 208. Diagram of Connections for Surface Contact Railway Plate
System, General Electric Co.
as stated above. As the car proceeds, the shoe D spans the plates B and C*
thereby keeping the coll of switch No. 2 energised after shoe has left plate
C, and until shoe £ comes in contact with plate J, which immediately ener>
gizes coil No. 1, thus making the preceding oontact plate energised, prepaiap
tory to the further advance of the oar. It will be noted in the above
description of the performance of the system, that we have assumed switdi
No. 2 on Fig. 208 as closed; it should therefore be understood that an aux-
iliary battery circuit is necessary in startlntr or raising a first switch, pre-
paratory to its armature being held in oontact position by the generator
current, which current energises the preceding contact plates oonaecutiT^
as described above.
The battery current Is brought into the automatic switch circuit momen-
tarily during the pwiod of flrat movement of handle of the controller in
starting a car, the transition of the controller cylinder also bringing the
generator current In connection with the battery for a short periodof time,
thus replenishing the elements sufBolently to operate the switches. The
battery is also used to supply current for lightmg the car, the generator
circuit b^g disconnected while the car is at rest.
•nrfacc Contact Platoa.
The surface contact plates are made of cast iron, with wearing surfaces
well chilled, designed to be leaded into cast-Iron seats in such a manner
that they are thoroughlv secure, but can be readily removed by ^spedal
Umg» for the purpose, ^e sent is imbedded in a wooden or composition
block set into a cast-Iron box, the latter beins spiked or screwed to the tie.
A brass terminal is fastened to the seat for the reception of the connecting
wire from the switch. See Fig. 209.
. E. CO. SURFACE CONTACT SYSTEM.
AaiMtad kbore, the pUMa ua niokllj liMsMd 10 fMtuiut (otitnl|Ai(
line work, bat ■omewhut cloaer on outtei, depandlng npoD the ndliu of Uu
■ndlansthofMntutttuM. The nagUlTe uuTpoalilTQ oontMt pUt«a
" 'u dlMiiuoe betnan them, altDBted not
>» lUgiered with k unUonn ■uguliu' dla
tflM thmn 10 InoliM £rom the irmol nlil.
i
i
i
•■rfaca CratMst •wltcb.
re of Thlch la emptojad b
PlO.210. AQl«iiiMlaSwltohforOt>«iiC<}Ddt)lt,BQtfiMMPlateOoiit)H:tBT(taia.
G. E. CO. SURFACE CONTACT SYSTEM. 851
The batteriat are only lUghtly ezhaiuted In making the initial oonneo-
tiona through the automatic switch, as it only takes approximately 15 am-
peres momentarily to perform this work, the battery is immediately
rooharged by current wnioh has passed through the motors. The battery
■erring as a rheostatic step, this momentary charging does not represent
airr extra loss of eneisy.
The circuit connections of the battery are accomplished in the controller
and require no attention on the part ol the motorman.
The amount of reohu-ging derived from the motor circuits Is sufficient to
operate the automatic switches, but where lighting of the car is done from
the same battery, an additional recharge is required.
Assuming that 10 20-Tolt lamps are used for lighting a car, the batteries
will need to be recharged every night about five nours, at an approximate
rate of 25 amperes.
It is customary to rmi leads from both the positive and negative terminals
of the batteries to charging-sockets attached to the under side of one of
the car sills in a convenient place for connection to the charglng-wire.
A small generator of low potential (30 volts) driven by a motor or other
method is required for supplying current for recharging the batteries where
the desired low-potential current is not accessible, and the wiring from the
charging source should be run to a location in the car-house most convenient
for connections to the battery sockets. These locations may be fixed either
in the pits or on posts at the nearest point to where the cars will be sta-
tioned, and there should be flexible lead wires attached to plugs for connect-
ing to the battery circuit on the car. In wiring the car-nouse for the
battery connections, it would be found convenient to designate the polarity
of the various wires either bv diiferent colored insulation or tags, and the
plugs at the ends of the flexible leads should be marked plus and minus to
avoid mistakes in making connections with the car battery receptacle.
Motoiw aadl Controllera.
The motor and controller equipment used with the surface plate contact
system is standard apparatus as ordinarily employed for electric car servioe,
with the exception that provision is made in the controller for cutting in
SAd out the storage battery while starting the car.
Care vt Apparai
As success in the operation of the contact plate system depends largely
on the care of the apparatus, a few general remarks on the subject will not
be out of place here.
Care should be taken that the contact plates are kept clean, and they
should be frequently inspected, the roadbea being well drained. Any small
anantity of water temporarily standing over the tracks, however, would do
ttle harm, as the leakage through the water would not be sufficient to
ereate a short circuit, although this condition should not be allowed to
exist any length of time.
The automatic switches should be carefully inspected and all cast-iron
parts thoroughly coated with heavy insulating paint, and a test for insula-
tion or grounds be made frequently, and all the parte kept clean and free
from moisture.
The contact shoes, in order to prevent leakage, should have their wooden
supports well protected with a coating of an Insulating paint, and should
also be occasions Uy cleaned.
The storage batteries should be properly boxed and should have the ous
tomary care which is necessary to keep them in good working order.
ITBBIORATION OF UNDBRGBOUITO
METALS DUE TO ELECTBO-
LYTIC ACTION.
Rbvisbd bt a. a. KNitDaoN. BUcthcal Bneii
: dectroli
III el ths aubjaot
if tb» diff«i*nt pbMM ud effen* of electrolytio i
'. seenu ewwntiu, whiuv a cJaat iansht of tha AubJAot ia c
[ii«ef which undsrlie ths prindpJvs of Buch
and ths Mlaving is abstrKted from ths Rtparl of On E
Iht Natimal Board if Firt UndmrrUnr; PampUtl No. a. wuaa
sea, vii: This d»Ji with ear]]/ diHOTsris slid represciiti the
la Bivcb by severkl muthoritiH ud thift subject si
JO ui thi« articJe ia treated in a pur«Jy prerrtical inennvr.
reports ghow that ths dsstruotivs effects of slectric*] our
metal pipes are beooming sufficiently marked in n_ , ^_ ._
/ to seriously interEere with the ssrvjes the jHpeaare intended
id water mains have broken down, because of faults unoues-
Buch an extent as to break at critical luornvnUi. when eicea
u unquratiooably exist in nurl^ every district in the United
eed elaborate doeriptinn. Briefly it may be compared to tha
ich takca place in an electro-platini bath.
rent whieh enters the bath tbrough thn njekd or rilver metal bd*-
arcdn. Sowing throuch thn bath and out through the object to be
timatelr brinsi about the deetniclinn of the suapcnded piece of
imilafly., the ourrenl from a grouDded trolley syRtnn flowing
I pMh of least reaietanoe,* which is generally for the whole or a
to reaob the station the iron at the pipe wastes away until at
I walls become too thin to withatanil the pressure of the water,
DTOUndinv earth, such acti
er, then, a reading is shnwn by an ordinary portable Toltroatar
; tenths of a volt with ths positivs bindiog^ost in electrical oon-
lection with an adjacent lamp-post, car track, or metal rod driTSD
Lh. electrolytic action will be found upon examination to be tak'
It that point which will ultimately result in the deettuctioa of the
I, provided that the reeiatanoe ol Ihesoil is sufficieatly low to
the generator out over the troTley line, through the motor to rail.
ELECTROLYTIC ACTION. 853
eurreot. One ft return through the rail, the other a return through the
earth and any existing gaa-pipes, water maine, or other metallic strueturea
that noay be in its iMtth in the earth. The current flowing through these two
paths in parallel is plainly inversely proportional to the resistance of these
two paths. Therefore, in a general way the current will leave the rails at
A, flowing into the water-i>ipe at B, and will a^n leave the water-pipe at
C and enter the rails. Here, then, is an electric ctirrent flowing between
metallic structures that may be called electrodes at places in the return
path from the motor to station. AU that remains, then, to promote
^ectrolytic action is the presence of some solution which will act as an
eleetrol3rte. .
Observation has shown that the earth, especially in the larger cities, con-
tains a large percentage of metallic salts in solution, which will readily act
M electrolytes upon the passage of electric current. It can be seen, then,
referring to this disfnam, that if there exists in the ground suflicient moist-
ure of some metallic salt, electrolytic action will take place between the
electrodes A and B, aud between the electrodes 0 and the rails. In the earlier
deetrio roads the positive terminals of the generators were connected to
ground. This arrangement of the polarity of the street railway has a
tendency to distribute the points of danger on water-pipes, gas-pipes, cable-
sh^thing, or any other undergrotmd metallic structure throughout a large
and extended territory. By reversing the polarity of the railway generator.
"\..u 'E%i
eCATIOH
Fio. 1.
bringing the positive terminal to line and negative to ground, the points
where the eurrent leaves these metallic structures will be brought much
never the power station, and will be localised in a much smaller area.
*rpm the electric railway standpoint, the prohibitive expense of the
requisite addition of copper to make a complete circuit is advanced, to-
gether with the impracticability of a double-trolley sjrstem that is appar-
ently a necessary concomitant of the metallic return; and these arguments
have ascertain weight. ^ There is no question but that the complete metallic
return is in the begjnmng a more expensive installation, but per contra few
railway ooinpames have any idea of the energy now expended in returning
the energy delivered by the power station through the poor conductivity of
theavwage railwaytrack with its surrounding earth.
IPeaU««ttye IBfl'ecto. — In the process of electrolysis upon under-
mund pipes there are two distinct phases of action considered as follows:
A, the taUraleffeel which is most common, illustrated by Fim. 2, 3, 4 and
B, thejKjnis^ertasshownin Fig. 6. .^ »« . .
A, Where the current is leaving a cast iron main and passing into the soil
the iron is usually removed in spots, causing pittings of varied sise and depth,
spondingly iBTfser surfaces.
When a section of cast iron pipe contwning such pittings has been removed
"?°l- w /i?" ^.. •'^'^■^.to the sun, the graphitic carbon and impurities,
of which the pittings are filled, become dry and hard and drop out or are easily
renooved. In appearance they are flat, or nearly so, at the surface of the
pipe and oval in depth, as in Fig. 2.
These are J of the actual size and shape taken from a pipe. In weight
*"fKi?" *feli* *J»o.8ame as dry wood of equal dimensions.
s rL~®SS:'^-^*® ^^^^^ ^ ^^^ severe and the main has burst, the most
of these impunUes will have become detached or washed out by the force of
<
ELECTROLYTIC ACTION. S55
8. Joint Elttet — llii ii eitusiil by dsotriB eum&U Bowing through at
alone tb* inp« l«ictbwi». sod by reuoa of mUUnce K Cba joints, elac-
tnlytio action talua nlue. RonitsacB ia cuised partly by the ooitinc of
wpbtlt vuniih upon both the inside and outside of the pipe, mskiue sputial
inmilmtioD; and iiartJy by corruaioa due to the coDtiaueu prneacB of watu^
■aunt* th« iouit, the damace occurriof al puinle where it IPAves. cauflinc
[dttiue in Um iron doHto the lead, Kiitaniiia of tha lead, [eeultini in lealu.
fit. (T — the iiriEat end of acast iron pipe — «howB caiue of a leak through
diaintceiation ofthe iiDD D«at the lend of Cheiaiat; thefurroirof initings —
between obalk-nlarki — extend half way around the :npc: the left end of
the pipe laflened three-eishth* of an inch deep waa cut with a pociiet knife.
The otonl oE icunt dama^ depeoda upon the atrength of current Qowjiic in
The action upoa wrought iron or cteel iripea diSera aomewhat from that
upon out iiDU. In the reduction of wroucht troD by the pro«e«, there ii
ft Msmy, or shradded wipearanoe, with but little nqdual earbou. Upon
Meel «uoh «a (ha bawi of M«l raila, or rail ohaira (the latter now little uaed).
the effeet i* a nMdHncawayaf the metal, leaving aliarp edgea at their twttom
portioiu. This effect ia found where raila are positive to pipes-
ThBMtion upoo lead aervice pipee, or lead covBring upon eabl», is aoma-
eamed, but InauauTof the (nphitic reeidue there i> left in the pitiings and
the aorrounding aul a whitiah matter conaiBting of the ojtidc or midue of
lead.
Ms^a to Hatla «r to ifoevtiTe CoiMlacton.
Meaaurementa in different dliee under Tarying conditione ahow the in-
ereued How of current through mains after bondine the maine to the raJIs,
(roia four to ten times above the normal at iwinta near the bonds, in aome
caaea veiy much higher. In one rase where 5 amperea marimum waa found
Sowing throngh a IT' main a temporary oonnnjtion with ammeter and leada
waa made between mala and P H nORalive mth reeult of ovBrlSOamperee.
The flow in axeeaa of normal ia gena-ally lees aa the duUmoe is mcreaaed
856
ELECTROLYSIS.
The following tables represent actual measurements made in differeat
dties. Measurements made near the bonds, except in No. 3, Table 1.
Tal»le S.
Flow in
Amperes.
No. of
Notes.
Test.
Normal.
Connected.
1
21.0
41.7
2
21.0
60.2
3 bonds.
8
30.5
4.3
3000 ft. from bond.
4
5.0
128.0
In negative district 5 mile
from P.H.
6
6.0
32.0
Genera, Switierland.
6
11.5
37.5
7
80.0
125.0
8
27.7
45.1
9
9.8
80.5
10
6.6
10.5
Table H.
Three Cases Difference of Potential in Average Volts.
In one city examined by the writer two water mains in front of a power
house were connected by copper cables directly to the negative bus tmr of
the switchboard. The estimated amount of current flowing by this path was
found at times to be over 1000 amperes; a very much smaller flow has been
known to damage the joints of mains.
Carr«Mt AovemeBto vpoM 'WJnd^rgr^nmA MaIim. — The
flow of current upon underground mains is proportional to the traflBe
upon the car lines. When raUway traffic is heavy inomings and eveningi
more current output is required at the power house than during hours of
light loads. Such changes are faithfully reflected by current flowing in the
mains. This is illustrated in curve sheet. Fig. 7, where the load line of a
24-hour log of a power house is shown, and directly above it is placed the
line of current strength flowing through a 36-inoh water main. It will be
notioed that the rise and fall of current strength upon the water main takes
place at the same hours of the twenty-four as the load changes at the power
house. This effect is more or less common in all cities where electric railways
with the usual ground return prevail.
Many instances of railway currents flowing through and across waterways
have been discovered, where, as is often the case, the power house is located
upon the banks.
One instance of such action was discovered at Bayonne, N.J., November,
1904. At that time current was supplied from the Power house in Jersey
City, five miles from the central part of Bayonne. The city is nearly sur^
rounded by salt water. Mains in streets near the shore and in salt marsh
BLECTROLTTIC ACTION.
iON CU«Vt5
RENT VARIATIONS
ER MAIN 24 MRS.
^T
,
f|
2
li
i
?
I
i^\°v
A
!
11
i\
w
I
/
\
V,
\
\
! «
«!■
ELECTROLYSIS.
ling s heavy ton in pipinc property to the city by »lectrolyiu.
0 point in the dly where muni were poeJlive l« the nili:
te m discovered by' tbe miUr in 1908 during > lurvn in
!*Dn>tito, Ouiada. where mains jtdiacent to the shore of Lska
4 miies dist&noefiom the powar house, were bbUy d^r
HI in BATOrme have been chaoged by the plasins of
Cases have bsea
alus in tha (team p1i_._.
8. aswas dfiooverwi in Ihrcity'of New Y^
through [4paa
tS. as was disooverwi in the city of New York.
UM is located near the Navy Yard, in BrooUj^. Aportba
ingeurren^ , as _ _wo^ y arrowe.^ wiover_^^ Wllli™l>ur«
atlTet, Co power booiie. In this cue damage may be einwtsd
ts, tit,, where curTeiitn leave brldse meUli nn the Kfanfiattiui
■ley leare pipes to enter WIllLaniBhnrg bridge, where Ebey leave
for pipes oil Brooklyn side. When the t<*ci bridge structurea
I Id Manhnttnn as proposed, then there will be further change*
new briilge was built, these currents reCTnnecl Ihrough lbs
ning mains all along the docks on the Manhattan sde, for th*
kving At riirr for mains or other metoLi ak>iig the docks of
I side. Traces of thne currents have been Ibund as tmr norlk
diatanee of over two miln from the Brooklyn Bridge
fVilliamBbuis Bridge bu been built, nearly all traces of thne
ing north oi it have clisappcaroJ. nhowing that the maaa of
ung the etrurture ads as a "short rircuit " or palll <jt lower
i now carries praclirally all of the returning ournota flowing
T*lt Wtictrlm ■><>■ IFater KlaMra. ^ This is a eompaiB-
discovery, and is due to the Incalion in which many metcn
rhose found daraavHl bv electrolysis in one dty examined hav«
t>Bcn taken from pits in the cellar bottoms ot dw^ngs. etorta,
Fjng thelo'
ELECTROLYTIC ACTION. 859
The quality of auch liquid makes a convenient eleetroiytio for any current
of eleetoidty. Railway or other current paaaing to the meter through
the service pipes, and out of the meter into this liquid, in time causes a
rupture c^ the thm iron shell of the small sises where the top is iron.
llie actual weight of iron lost through electrolysis by a 4-inch meter located
in a ferry house and subject to tide watw was in about six years 15 pounds.
This meter was near a power house where the p.d. at times reached 2S5
Tolts, with mains positive to rails. These severe electrical conditions have
■inee been modified by the railwav company improving their track return.
Meters constructed of bronse have had holes eaten through their base
where resting on damp soil in odlars. Such grounds often attract trolley
eiurrent thiou^ the service pipes.*
^^mm^^rnmrnk Fire or BxploatosM. — Currents entering buildings
which contain explosives, through water or gas mains, are dangerous owing
to snarks when gas mains are separated or the cross-connecting and discon-
necting of pipee containing current, by movable metals is made.
The usual course of such currents is to enter a building on one pipe and
poos out upon another when a cross-connection is made between the two
systems anywhere inade of a building. When the connection is broken the
qiark appears, and it may appear at any point in the building, possibly
in the presence of explosives.
Bonding the pipes together where they enter the building has proved
effective as a temporarv remedy in some cases. As no two cases are auke, no
particular rule can be laid down as a remedy. Where the oonditions are
considwM dangerous the services of a specialist should be engaged.
filoctrolysis !■ Stool JFranao Bf«iUlinc*« — While no instance of
serious damage to a steel structure through the disintegration of supports
caused by dectrolytic action can be dted, still this question is now receiving
attention by architects and others, and methods for safeguarding ai;;ainst
such corrosive effects are being applied. One such instance of protection is
the new New York Time* buildiiig. In one of their publications the fol-
lowing is stated in reference to this structure:
"The dan^ that in case of the steel frame rusting the disintegration
of electrolysis would hasten the process of dissolution so much as to make
structures of this kind prematurely unsafe through the destruction of their
supports, was recognised in time to permit of ample safeguarding in the
case of the steel fraiae of the Ttmss Building.
" It is axiomatic that columns to which moisture has no access will not be
impaired by rusting, and that those effectually insulated from vagrant
electrical currents will not be iJTected by electrolysis. The first considera-
tion was to keep the basements dry; hence the thorough waterproofing
and draining of the retaining walls already described, which was also carrira
under the floor of the pressroom, occupying the great area of the sub-
basement. As a further safeguard, all the steel members up to the street
level are incased in Portland cement mortar to the minimum thickness of
three-fourths of an inch. This is effectual protection against rust deten-
orataon. Under these conditions electrolytic dirintegration is deemed
impossible, but the probability of its occurrence in even microscopic defrree
IS rendered still further remote by as perfect insulation as can be provided.
There is sufficient grounding to relieve any electrical tension which may
exist in any part oT the steel frame by drawing off the current at pomts
where electronic action cannot be set up. Tfis also makes it hghtninj-
pnxrf to the extent to which it is possible to impart that quality to a bmld-
For results of experiments by the writer upon metals »n.^ concrete, see
Febmary, 1907. Proceedings of the A.I.E.E. in a paper, entitled Electro-
lytic Corrosion on Iron or Steel in Concrete," discussion m Apnl number.
~ ~ % — The transfer of currents between the tracks ol
different companies through underground routes, often by way of ™*J'*f''
is of frequent occurrence, particularly if the lines parallel even for a snort
distance.
This is more noticeable at the terminus of suburban lines, but also pre-
vails in cities.
♦ Case illustrated in abstract of the writer's report for Providence, R.I.
In Water and Qaa Review, N.Y., March. 1907.
860 ELECTROLYSIS.
One oaM in a oity where the termini of two different lines were but a few
feet apart, showed upon measurement a heavy delivery at times, leaving
tracks of one company for tracks of another, soil conditions oontinually
wet, conseciuently a large percentage was flowing through soil and the
watw mains. Another case near suburban terminals ot two railway
lines about 000 feet of 6-inch water main with a number of service
pipes ware practically destroyed by electrolysis; the main acted as an inters
mediate conductor; the pipes were destroyed under the tracks of one road
hu Ike curreiUa from the other. An attempt to remedy was made by bonding
tne two tracks together. This method cut the potential difference be-
tween mains and rails from 6.7 volts down to about 2 volts. After six
months' standing no further breaks in the mains have occurred. This plan
was considered of value in a£Fording temporarv relief, but is not now of
importance as the tracks of the two lines have been joined by new tracks
in a cross street.
Current swapping is more frequent than generally supposed, and is caused
largely by loci^ conditions, such as swamps, rivers or other waierwmya to
which a company's tracks connect and are grounded, offering paths wiiidi
attract their own as well as foreign currents. In the case cited of damaced
mains, the flow was from newly eonelnttted (rodbs, seeking grounds on anotnsr
road where rails were in wet soil. Usually, however, the cause is due to
opposite reasons, vis., currents seeking a track return of lower resistance.
A well-constructed road bed on suburban lines will often avoid saoh
opportunity for grounds, and current swapping.
Alt«ni«tliigr»Carreiit Kle<;trolyal».
The possibility of damage to underground structures by alternating
currents has been investigated by several authorities both in this ana
foreign countries. As no actual damage has yet been discovered so far as
known to the writer, these Investigntions are necessarily confined to labor-
atory experiments. The following abstracts from a few papers give a fair
Idea of what is known of the subject, and where further Informatlou may be
obtained.
The Ultimate Solution qf the ElectrolwHe Problem by 8. P. Obacb, paper
before the Pittsburg, Pa., Branch A.LE.E., read December 12, 1906:
" Our many hundreds of laboratory tests have shown us that the electrol-
ysis to be expected from alternating currents is by no means negligible,
and that while it is far loss than that encountered with direct currents, In
practice wo should anticipate that it Is onlv a question of time until Its
action would destroy many millions of dollars of underground metallic
structures."
From transactions of the Farady Society, Volume I, February, 1906, Part 4.
Alternating-Current Electrolysis as shoum by Oscillograph Records^
by W. R. CooPBB, M.A.B. So., read October 31, 1905:
Photoffraphio reproductions of oscillograph records are given illustrating
results of his investigations. The author also gives results of several other
investigators of this subject.
From transactions of the Farady Society, Volume I, August, 1906, Part 3.
Alternate Current Electrolysis by Pbof. Ebkebt Wilson, paper read
July 3, 1905:
The author gives results upon different metals at different frequencies
and In different solutions, and begins by saying, ** It is well known that if
an alternate current be passed between metal eleotrodes in an electrolyte,
electrolysis may take place."
The Electrolysis Problem ftom the Cable Manufactwrers* Sta/ndptHUt^ by
H. W. FisHRR, paper before A. I. E. £., Pittsburg, Pa. Branch, read
December 12, 1905:
'* My experiments have not been very comprehensive, but I have found
under certain conditions, destructive electrolytic action may occur with
altoruating currents operating at a frequency of 60 cycles per second.
The solution I employed for the electrolyte was water containing oomjnon
ELECTROLYTIC ACTION.
861
■alt and galammoniae, all of which may occur in and around duct ayBtemB. I
found that with a current density of 0.1 ampere per sq. In. of lead, there
no electrolytio action.
Amperee per sq. in.
of Snrface.
Lead Destroyed per
Ampere, per hour,
per eq. in.
3.04
11.8
17.9
.004 Grammes.
.136
.237 • "
with a frequency of 25 cycles per second, the alternating
onrrent action would probably be greater than shown by my tests." This
latter statement agrees with Prof. Wilson's tests above referred to, where
he um, ** It will be seen from the table that the total diminution in weight,
which was equally distributed between the two plates, in a glTcn cell is
nearly twice as great at low frequency as it is at high frequency.'*
jawnawJiswi — Several methods have been suggested for counteracting
the eril effecte of electrolysis.
Tke ittmtated metaUic ctrcuil.
The underground, known as the "slotted conduit," has been in sucoese-
fal praotioal use in the borough of Manhattan, city of New York, some
ten years, and for a still longer time in the city of Washington, D. C.
The double overhead trolley has been in successful practical use in the
euburlM of the dty of Washington for some years, and in the dty of
Cincinnati, Ohio, since 1880, ana more recently has been established in the
city of Havana, Cuba.
Both outgoing and return conductors of either construction are insu-
lated; where there is no connection to the rails or ground the currents which
propel the cars are confined to their respeciive conductors, consequently
no damage to underground metals is possible.
Improved Track Rtturr^
Next to the double trolley, this method is probably the beet, although
a modification of the trouble.
In some cities a large amount of copper for returns has beenjplaeed for
this pumose, as well as heavy double bonding at the rail joints. The expense
involved in providing copper returns sufficient to give a fair degree oi pro-
tection to mains, would m most cases be considered unnecessary by the
railway companies, unless compelled by law.
Bonding Main* to Ae Track CircuiL
This has been done in some cities for the purpose of protecting a positive
area, where electrolysis was found to be acute; usually this is near a power
house. Some effects of such bonding have been mentioned.
While this may ]^rotect from injury the immediate area where such con-
nections are made, it is likely to aggravate joint corrosion by the increased
flow which has been pointed out.
Hf •<•■«• — A remedy for exterior electrolysis upon meters is to place
them in iron or other receptacles under a sidewalk where they will be free
from liquids or damp soil. Such methods are used in the cities of Cleveland,
Ohio; Uichmond, Va.; and Louisville. Ky. Official reports show in such case
they are in no danger from electrolysis, or from freezing, and are easily
accessible for reading, and removing when desired.
KManlatiar J'ointe In IHDatna. — This is a further attempt at remedy,
and much attention has been given to this phase of the suDJect by rail-
way companies in Boston, Mass., with the Metropolitan Water Works
oo5perating.
The Metropolitan Official Report dated January, 1005, contains much
information on this and other attempts to stop the current action which
• In this case a large hole was eaten through the lead, and the surface
exposed to electrolytic action was nearly a square inch.
BLECTROLTSia.
K nuin. UnulLy, howevi
s tried o[ t<ro ioiatt i
ther with rubber. J
Evli=^lP^
■^
itr tmt batirMD A and C gave BO to 110 unpera
If there were no joints. Between A and B, aow pi
bb«) O.S la 1.0 ampere. Between B ■ ' " '
'.) 0.1 unpere. This muling ahouli
aked. Twq Joints wer.
mil
nrrfrr
iothoesol
■ubber.
^r''
-%r.pp,
-,«, ^
4a-in
■i!'
S5.":
^h
burlap
n, thi> met bod
ELECTHOLYTIC ACTION.
m
i
, Ths Undmeu at r
power ho^ i. to leave tha
Thi» may be by way of other
raoVs near a terminus and
seek "poun
traoks. by way of undergro
nd marns, o
Jis
low that a vary good return
oonstruotion
sioQ o( currents.
v's road bed. where raila are
in contact with
wet »il. offer an altracUve outlet for their own. or foreign
nirreDt..
3. Bondinc nili to taaioB
f cuiTcnta to
the
ifacturing or carrying eip
orives should be
' oontiguoui to electric rsilwayB, and il ir
B. Protection of metal fou
m the pasHing of m raying
daliona of import ant struct
urreiits mto
and
tall
offi« buildinc. briden. etc.,
roiB olectrolylie action nho
ll"'be well
■idered before their ronstruFt
railway traclu Jhould Ee soug
in citl™ or towM where uoiH
^The cause for current swapping bet
ht out and removed where jn
Mihle. eepecialiy
ergrouad mains are likely 1
D be included ai
f tracks of
[i'ef. '" """ *** '""'"°' °
water maina have proven eSeotive to stou
r«n> flow >D »n.e »«., but
often at the eipeow of diverting il to o
her
™."no complete, oure for
tb*
TRANSMISSION OP POWHB.
Bbvubd or F. A. C. Pebbuib.
tann " Tnmtmiitlon iif JVhht." u iu«d by •lactrle*! encliMBn, bm
o hkTa m oanTaDtltuUkt meuilnB uhleli dJfiwsntUlM It from «hM
« sonililBTeil it* tail monlna- Anr tnninilulon of alwtrla eairait,
jterer pmctlul pDrpoae, wGather tor llgliUog, hesttug. (naUod, or
drlTtng, miut of oourae b* » truwniMlon of pov«r ; **■'* '*•" — — — -
" ° ,.. .1 — , „"oot«7 ,-
L from m jnor« or lea dlituit point oi
nuu m Inlon , ieVlba 'tonaeilS ~DBT8r~Bl'i uded" t<
rerlng milet of tucrltory, uid yet It 1* odI^ kUndwl U
J «nglnQ«rliig teatutoa of tranKmiuion nf poMur vlLl b« fonnd trvatad
the Hpmnte liuda In their mpeotJTe oh>pten, and (ha foUowlMf li
Stmotoral oondlUon* and matarUl.
maUv* Power.
Wntor poirsr : Tarblnw, eU:.
SteAin power : boUers and appllonoee.
Knglnei >Dd nppllanoM.
I>Tiiainoa : DIreat c
DlatrlbBlliiar Appltui»B.
SptrtUtloni and terminal haoen.
BwltebboBrdi.' high tendon and aaoondarr.
Freq uBoci'Jihaiiiwn,
DUtrlbulIng clrcolti.
DISTRIBUTING APPLIANCES.
865
Mvch hM been written regarding the relatiye valuee of the different
methods of transmitting power, and comparison is often made between the
following types, i.e.,
a. Wire rope transmission.
b. Hydraulic transmission, high pressure.
e, Hydraulic transmission, low pressure.
d, €k>mpre8sed bAt transmission.
0. Steam distribution for i>ower.
/. Gas transmission.
ff. Electrical transmission.
All of the first six methods listed hare so many limitations as to distance,
efficiency, adaptability, elasticity, etc., that electricity is fast becoming the
standard method. Tne matter of efllciency alone at long distances is one
of the best arguments in its favor, and we take from Prof. Unwin's book,
** DeTCIopment and Transmission of Power," the following table of the effl-
eiencies such as have been found in practice.
System.
Wire rope
Hydraulio high pressure .....
Hydraulic low pressure
Pneumatic
Pneumatic reheated virtual efAcieney
Electric . .
Per Gent Efficiency at
Full Load
Half Load
96.7*
93.4*
»
46
60
60
51
44
76
04
78
66
For short distances out of doors, transmission by wire rope is much used
both in the United States and Europe, and where but few spans are neces-
sary, say less than four, it Is obvious that the efficiency is veir high.
Hydraulic transmission is in considerable use in England, but except for
elevator (lift) service is in little use in the United States.
Pneumatic transmission Is in wide use In Paris, but not so for general
distribution in the United States, although for shop transmissions for use
on small cranes and special tools is making good progress, the principal
usage being for the operation of mining drills, noists and pumps.
Eiectricu transmission is so elastic and so adaptable to varied usee, and
has been pushed forward by so good talent, a not small factor, that its pro-
gress and growth have been simply phenomenal. In one place alone, that
of traveling cranes for machine sinops, it has revolutionised the handling
of material, and has chei^yened the product by enabling more work to be
done by the same help. Indeed the great increase in size of imits which is
such a distinguishing characteristic of modern engineering has been ren-
dered possible by the capacity of the electric traveling crane for lifting
great weights.
BUctrio Pimer TransmUaion may be divided into two classes, i.e., long
distance, for which high tension alternating current is exclusively used ;
and local or short distance transmission, for which either direct current or
polyphase alternating current are both adapted, with the use of the former
largely predominating owing perhaps to two factors: a, the much earlier
development of direct current machinery, and 6, to the fact that a large
number of manufacturers are engaged in the building of direct current
machinery. Both types of current have their special advantages, and
engineering opinion is, and will probably remain, divided as to which has
Uie greater value. n 't
* Per span.
866 TRANSMISSION OF POWER.
Long diaianee transminlon is now aeoomplished bv botb three^bMe
three-wire, and by the two-phase fonr-wire syfltems, with the former pre-
dominating for the greatest distances, owing to economy of copper.
£very case of electric transmission presents its own problem, and needs
thorough engineering study to decide what system is beet adapted for the
particular case.
Limitaticna of Voltage.— While 10,000 volts pressure was nsed with some
distrust for a time preylous to 1898, since that time yoltages up to 70,000
volts have been and are still in use with substantial satlsfaotton, and i^uts
using voltages of 80,000 and 100,000 are under construction.
Properly designed glass or porcelain insulators, made of the proper
material and tested under high pressure conditions, cause little Ut>ui>le
from puncture or leakage. The latter is its own cure, for the reason that
the leakage of current over the surface of the insulator dries up the mois-
ture. Dry air, snow, and rain-water are fairlygood insulators, and offer no
difficulties for the ordinary high voltages. XMrt, carbon from locomotive
smoke, dust from the earth, and such foreign material that may be lodged
on the insulators, are sure to cause trouble. In the West and some sections
of the East many insulators are broken by bullets flred by the omnipresent
marksman.
At the lower voltages glass makes a satisfactory insulator, as the eye can
make all necessary tests ; but it is so fraffile that porcelain is more com-
monly used. It is not safe to accept a single porcelain insulator without a
test with a pressure at least twice as great as that to be used.
Mr. Ralph D. Mershon of the Westinghouse Electric & Manufacturing
Company made a long series of tests at Telluride, Col., on the high-pressure
lines in use there, with a No. 6 B. & S. copper wire he found that at BOfiCO
volts there will be a brush discharge or leakage from one wire to the next
that can be seen at night, and makes a hissing noise that can be heard a
hundred feet or more. This brush discharge besins to show at about 20,000
volts, on dark nights, and increases very rapidly, as does also the power
loss at 50,000 volts and higher. This loss depends upon the distance futart
of the conductors and their size. For these reasons, wires should be kept
well apart and be of as large size as other properties will allow.
The wave form of E.M.F. used also influences the brush dischaive, being
the least in effect for sine wave curves of E.M.F., and being much Cncreased
by the use of the sharp, high forms of curve.
In regard to the frequency to be adopted for power transmission, one has
to be governed by the case in hand, and the commercial frequencies avail-
able at economical cost.
UPSCEAI. FKAV1JRB8 OF DS0IO1V I»17B TO TRAITS.
MIfMIEOlV I.IIVK RK^VmSFlHEIfTII.
While the general requirements for the design of a power plant and line
for Ions distance power transmission are practically similar and theoreti-
cally identical witn those for other electrical installations, at the same time
special features are important. These are due to the character of service
required, the size of tne plants, high voltage, and location of the plants.
The general features of design have already been considered In this
book, and a short resume is given on page 864. Below, attention is called
to special requirements to be considered in power transmission instal-
latioUB.
JBiilldlngvi. -^ Transmission generation sta£loiu are commonly located
in relatively inaccessible locations, and the siae of unit is therefore limited,
whereas the total capacity of the station may be great and the current Is
transmitted at high potential.
Transportation and labor conditions must be carefullv studied, as the
neglect of this precaution may readily involve an underestimate of no less
than 26%, and has often so resulted in estimates otherwise correct. This
Is especially true as regards the use of patented or special building con-
struction, which might result in savings where competent workmen are to
be had, but which actually result in excessive cost where the amonnt of
work to be done is not sumcient to import men familiar with the type of
construction.
SPECIAL FEATURES OF DESIGN. 867
llo»llMr Thn bvildingi should be entirely fireproof, and whereM thto
is easily taKen care of by ayoiding wood altogether in the interior construc-
tion, supports and widls of the building, a mistake is often made in choos-
ing a roofing whi<^ must be laid upon planks. Such construction has
frequently resulted in disastrous fires at power plants otherwise inde-
structible.
■Seattisg'.— Where temperatures do not fall to less than l<f F. the
waste, of energy from the machines is commonly sufficient for heatinx ;
where lower temperatures are encountered, special prorisions must oe
made for heatlxig. Boilers for steam- or water-heating fired in cellars
accessible^ from the outside of the building only are the best.
0«tlf»te for Kigrli-TeMiioa W^lr«a.— In buildings where the tem-
perature falls below freesing, sewer pipes with larse openings for high-
tension wire outlets should not be used on account of the excessive dxaft
through these openings. A number of systems for high-tension wire out*
lets are described in TrantacHont of Jmerican Ifuitituie of Eltctrieal
Snginterst Vol. 22, p. 313 ; Vol. 23, p. 578 ; Vol. 25, p. 866. Special methods
for carrying out some of these plans hare been designed and are described
in the catalogues of the porcelain insulator manufacturers.
UclBtetair Arrceter Protection. — Arresters should be considered
as belonging to the line and not to power house, and lightning] arresters
should not be installed in the power house itself, but in a separate neigh-
boring enclosure especially erected. Arresters are to be considered as a
means for prerenting line disturbances entering the power house in any
manner.
Seiwnstinr CloMonstor and Vramfonnor ]|oonM.~The only
reason for attempting to separate generator and transformer rooms is on
account of the oil contained in tne transformers which may become the
source of fire haxard. If, howerer, the oil transformer is properly enclosed,
separate buildinss are unnecessary. See Transactiont ^ Amenean Insti-
tute of JBlectricM Enffineers, Vol. 23, p. 171.
Auxillaary Snildloira. — No estimate on an isolated transmission
power house is complete which does not include houses for the married
employees, a central mess house with reading room, assembly room and
offices, and stables for the accommodation of horses. Unless these features
are properly taken care of, it will be difficult to retain satisfactory em-
ployees and to operate the plant economically and continuously.
MOnirjB PO^TKlft.
"Wmtmr Poirer. —Load factor and total capacity are closely related
in questions of design and revenue.
Tne effect of yearly load factor on revenue is shown by the curves below.
By reducing all yearly load rates to a K.W.U. basis we are enabled,
through the use of these curves, to determine the total revenue to be
derived when we know the total yearly K.W.H. that any variable water
snjmly may sell when applied to the operation of any set of variable loads,
ana hence the value to the plant of an annual storage.
In "Tariable loads there is a variation in the daily load factor as well as in
the annual load factor.
A.pmwi flpOHi Plant.— These reservoirs serve to aid in properly sup-
plving variable annual load factor, but on account of plant distance, cannot
take care of daily variation in load factor.
A4|ncont to Plant.— When a daily variation of load factor is to be
met, revenue may be increased bv reservoirs near the plant that may be
called upon for conserving water flowing at low power periods and deliver-
ing it at pttsks, which oannot be done by distant storage.
AuLlUMy Powor.— The value of any plant should be based, not
upon the total maximum or minimum capacity, but upon the K.W.H. sala-
ble, and in obtaining the maximum K.W.H. capacity it is often possible to
inorease this by auxiliary machinery to be used at the low water periods or
TBANSUISSIOir OF POWEB.
at ptrloda oT e\a
THulM In Htlmat
Ad It 11*17 pooei
kbig at the niiMt
most sMlgfactorT
'■ puk. MegleotlDg II
■tnd; of thli factor ofloa
T gu. M li obtain-
5
Curre lor r«diidBg cost of pov«r
pov«r p«r niailmnm hone
lala sad otfedr CcBdalta. — Conatrofltion of opes
y the cheapaat iiiechod wksre water ia lo tie ourlml a lou
— •* '-Jcly uBllonn and capable of beiiia made tight.
a from canals inainlj bjalw ; the term "canal"
Dltchea are dlitingulihed (roin canals mainly by slie ; the ierm " cai
belD|r applied to Ignge open water carrlera»Bac] Is particularly applied w!
the (Ides and bottom are reinCorced lor redoolug motiOD or maintalDlBi
SPECIAL FEATURES OF DESIGN. 869
stmctnre. Where ground Is of Bnoh ebaraoter m indnoes leftkAge, or irhor*
■vrf aoe eTaporation is ezoesBlTe, It is neoeMarj to oarrr water through pipes
or throogh eneloeed condnlte. In snoh ease the conduit is run full and nnder
Seeanre, whioh means that the top of the eondolt mast always lie below
e hydraulic gradient. Economy in construction is obtained by running
close to the hydraulio gradient and concentrating the fall near the power
house.
PiM Uses or Pensiocks. — Pipe lines near the power house, where
a rapid fall greatly exceeding the slope of the hydraulic jgradient is allowed
for useful head, are generally called penstocks. Such lines are built at as
rapid a fall as possible and constructed of Tarious thicknesses or strengths
to conform to the increased water pressure.
J^h JLadders. — In all streams where there are any fisheries or where
the government is introducing spawn or small fish, the law requires the use
of flsh ladders, which must be included in the estimate on any such plant.
No standard type of ladder has erer been permanently adopted, and the
construction must depend upon the character of fish they are intended to
aerre. Salmon will go up ladders requiring jumps of from two to four feet;
but smaller fish, shad, trout, etc., must be provided with ladders with Jumps
not oyer one foot. These ladders consist of flume boxes rising from the
river to the point above the dam, each box rising slightly above the preced-
ing one from the river, and each allowing a rewtively quiet flow near the
dam into the next one.
■ITect of MIt mm 9tonic«. — ^o"^ streams carry more or less silt,
and have been known to carry as high as 13 tons of silt per second foot of
water per day. Under such circumstances the capacity of the storage is
often reduced, and where such conditions are encountered, only a small
proportion of the total storage area can be relied upon, unless special means
are provided for removing the silt. Dams will flll less rapidly with silt if
the surplus water during floods is carried olf through the bottom of the
dam ratner than over the crest.
Cliolce of Hoad.— It is an error to subdivide heads which are not
more than 2,000 feet in height, since pipe can be readilv obtained to handle
2,000 feet hMd, and sub-division of the head not only increases the cost of
Installation, but also the cost of operation. This is true, not only for high
heads, but for low, as the building of a high dam in place of two low onea
more than doubles the available storage. Exception to this is when rela-
tively constant load is to be operated, m which case the increase of storage
does not increase the total yearly K.W.Hs., and the cost of the high dam,
which is about double that for two low dams, is unwarranted. Here, as
sJways, the construction of the plant should depend upon the total yearly
K.W.HS. salable, without special reference to the total yearly K.W.Hs.
available for sale, unless it may definitely be shown that the surplus yearly
K.W.H8. salable at the time of construction can be increased by reason of
having a greater available quantity of energy.
Batlnsato of Water. — Excepting at the head waters of streams or
where an actual gauging is obtainable, it is unwise to estimate any stream
in the United States at a minimum greater than .26 per second foot per
square mile of drainage area. In the east and south this minimum is pro-
duced by the summer drought, whioh is also true on the Pacific CkMwt. In
the west and north this minimum is produced by the cold winter weather
when the streams are frozen and fiow diminishea below that of any other
period of the year. The best estimate of water flow can be obtained where
aoenrate gangings have been made by a careful and experienced govern-
ment office. Even these must be modified by a study of the local conditions
and of the rain fall. Where gaugings for a considerable period of time are
not obtainable, an approximate estimate of the water flow can be obtained
by a study of the ram fall and then compared with gaoflingB in a similar
locality, though the extreme minlmam cannot be obtained in this manner.
and a minimum considerably below that indicated by the rain fall should
be taken.
Coal Powor. — Ck>al power for transmission is only practical in one or
two conditions: First, where waste coal is obtainable ; and secondly, where
inaccessible coal can be marketed by transmission. Coal is primarily a
domestic fuel and material for chemical reduction. Its continued use for
power is only a question of relatively few years, excepting where coal can
be obtained which la not adapted to other purposes, or where it cannot
870 TRANSMISSION OP POWER.
readily be made aTallAble by other means^ Aa an auxiliary power material
it is well adapted for sapplementing the deflciencies of wMt&r power planU,
or for handling the peaks of loads, thereby enabling a greater total yearly
K.W.H. output from any given installation.
Fr«qa««cl«a.'^Thls subjeot is much oonfused at the present time.
Twenty-^re cycles has been a standard frequency for power work as it is
well adapted to use of the present type of syneluronous rotary converter.
It has never been well adapted to lighting work or to the induction motor,
and at the present time, with the strong development of single^hase rail-
road working, it is a questionable frequency for that service. A frequency
of 00 cycles is perfectly adapted to all lighting needs, motor generator
sets for conversion to direct current, and for inductor motor converters, as
well as the newer types of synchronous rotary converters. The elTect of
increasing the impeaanoe of the line at 00 cycles has not given added
trouble over that found when low frequencies are used, excepting in the
ease of linos delivering over 10,000 K. w. In any case of transmission the
frequencies must be determined by the market to be served, both for the im.
mediate future and the distant future, where power is available to oon>
template increased development. A choice of frequency different from
00 cycles must be well warranted by the circumstances, or not adopted.
wWltaipe. — IMrect generation of hish voltage should not be contem-
plated, excepting where the present and future market can be reached at
not over 600 volts per mile, when direct generation is not contemplated,
standard 2300 volt generation is to be preferred, unless the plant to be in-
stalled contains great capacity, in which case 0000 volt generation is pref-
erable.
HernlsitloA.— Close regulation for inductive loads should at all timee
be preferred, but in large stations, wh,ere the load is relatively steady, it
should be remembered that a change to 1,000 K.W. on a 10,000 K. w. machine
represents only one-tenth the variation of what the same change In load
means in a 1,000 K.W. machine.
Apetid. — Hiffh speed is always preferable in power honssa for transmis-
sion work. It snould be remembered, however, that for Impulse wheels the
correct speed of the wheel buckets is about one-half spouting velocity of
the water, and in consequence, all machinery should be installed to allow
a speed practically equal to full spouting velocity of the water when the
load goes otT.
For turbine wheels the speed Is approximately 7%, the moutlng velocity
of the water, and for no load does not increase more than 26%.
ftlse of IJnIta.— While large sized units are preferable, units should
not be chosen which are greatly underloaded for long periods of the day,
nor should units be adoptM which do not allow the installation of at least
one spare at the maximum load.
Un« of IMrort CarroM*. — In the United States direct current to-day
is practically unused. In Europe it Is somewhat used in Italy and Switser-
land. The success obtained by the use of direct current where It has been
employed, and the recent developments in the design of direct current
machines warrants Its future employment, but as direct current is only used
in constant current circuits the line loss Is constant, and is onlv warranted
where there is constantly flowing a surplusage of water which cannot be
conserved.
TRAlfSlCKt'mifCF apipahawts.
Awltchboarda. — For transmission plants which run to very high line
Toltase, it is preferable, even in comparatively small stations, to install the
high tension oil switches in such a manner as will not tend toward the
destruction of the plant should they fail and bum. The lower tension gen-
erator switches may be installed in the line of generator leads without
attempting to bring the generator leads to one central point for re-distrlbn-
tion of the current from that point. These provisions can be carried out by
\
8PECTAL FEATURES OF DESIGN. 871
means of the installation of centrally located distant control switches,
while keys or switches are installed for operatinff the hig^h and low tension
twitches, without bringing any current aboye UO rolts to the operating
board.
•ftafle or HfolM-Phaao. — In large installations multi-phase trans-
formers reduce the number of units to be taken care of and the complexity
of the wiring. In the smaller Installations they involve a greater pro>
portion of spare units. Accordingly multi-phase transformers are to be
considered preferable to single phase, excepting where their sixe calls for
too much added machinery in the spare units.
PmvtoctlOB HMlmet Flr«.-~ A large majority of the transformers
used in transmission plants to-day are oil filled. Experience seems to
Indicate that this does not increase the fire hazard, excepting in so fnr aa
this is due to the presence of a large quantity of oil. When oil can be kept
eool and within the cases of the transformers it does not increase the
Are risk. It may be kent cool by circulating water rapidly through the
cooling coils in the transformers, though a separate enclosure of each trans-
former within a space where water may be sprayed on the outside of the
ease, or the enclosure filled with water, is a surer means than that of
relyinff on the circulating pipes, whenever any serious accident has occurred.
Accordingly transformers should be enclosed where water can readily flow
on them without damaging the remainder of the machinery. Transformers
through which the oil is circulated and the oil cooled outside the trans-
formers constitute a greater fire hazard than those in which the water
circulating coils are immersed in the oil within the case.
Another way is to provide a laree tank into which the oil from the trans-
formers may be drained in case ox fire.
POUB IiXlVJBA.
lilgrbt of 'WWrnw, — For hlsh tension work private rights of way are
to be preferred ana result in final economy in operation. Bights of way
adjacent to steam railroads result in difficulty with the insulation on
account of the coal smoke and are not to be sought. It is not generally
praetical to obtain a right of way so wide that in case the pole or tower line
fall it will fall entirely within the right of way. Width of from 60 to 100
feet is entirely practical, provided the additional right is given to cut
diseased trees within an additional 60 feet on either side of the right of way.
Character of construction has already been described under the following
headings : Wood poles, towers, cross-arms, pins, insulators, attachment of
inaulators*
BTOKAaS BATTERIES.
RjBViasD BY Lamar Lyndon.
■leaieAte. — The form of storage battery now in genend use is that in
which the electrodee are of sponoe lead (Pb) and lead pMoxide (PbOa)
which, when immersed in dilute sulphuric ado, form a voltaic couple. Its
action differs in no wise from that of the ordinaiy primary battery, excmt
that when it has given out all the energy that the chemicals present eDable
it to supply, instead of having to put in new chemicals, the cell can be
regeneratea or broui^t back to its original condition by paosing current
into it in a direction opposite to that in which the flow took place on di»-
charge. Obviously, there are many combinations which can be used as
storaoB batteries, but with the exception of the lead-sulphuric add battery,
none nas proven commercially practical, unless it be possibly the Edism
battery, which has lately appeared. This battery has for one of its cleo-
trodes, nickel oxide, and for the other, finely divided iron or iron spon^s,
these being immersed in a solution of sodium hydrate. Up to the present,
however, tneee cells have not been used for power work, and therefore tha
discussion will be confined to the lead battery.
The plate on which the lead peroxide is carried is termed the positive
plate, and the lead sponge nlate is termed the negative, the reason being
that on discharge, current nows from the lead peroxide plate and returns
to the battery via the lead n>onge plate. The condition, however, is the
opposite of this inside the oeu, as the current flows from the lead sponge
plate to the lead peroxide plate. Therefore, considered as a voltaic ooupM,
the lead sponge plate is the positive; considered as a souroe of electric
current, however, the lead peroxide plate is the positive, since it is fit>m
this dectrode that the current flows out.
Tlieorlea. — The first and oldest theory is that on discharge. Hydrogen,
which is rdeased at the lead peroxide plate (PbOs), combines with some of
the oxygen in the peroxide, forming water, and reducing the oxidisation
of the PoOa by one molecule of oxygen, bringing it to a state of lead oxide,
or PbO. At the sponge lead plate oxygen is released (these rdeased gases
coming, of course, from the electrolytic deoompodtion of the water in the
dectrcMy^), and this oxygen (O) combines with the sponge lead (Pb), and
oxidises it, caudng it also to become lead oxide (PbO). Thus the two
plates tend to approach the same chemical compodtion. If lead oxide
(PbO) be immersed in sulphuric add, it will be chemically attacked, inde-
pendentlv of any current flow, and change into lead sulphate, the ch«nical
reaction odng
PbO+H^04 - PbS04+H«0.
Thus the active material on both the plates tends to approach the oondi-
tion of lead sulphate.
On charge, the reverae condition takes place, the hydrogen bdn^ rdeased
at the negative plate and the oxygen bang released at the poeitive, the
hydrogen reducing the oxide in the n^cative plate and carrying it back to
its original condition of sponge lead, and the oxygen at the pnodtive increas-
ing the oxidisation of the podtive plate and returning it to its condition of
lead peroxide PbOs.
The later theory is that the plates do not pass through the intermediate
stage of bdng changed to lead oxide, but, on discharges, change direct^
from thdr respective states to that of lead sulphate. This theory is doubt-
less the correct one, for the reason that in the chemical change from lead
oxide to lead sulphate, heat is released, which represents lost energy, and
if this energy loss should take place it would be impoadble to get from the
storage battersr a large proportion of the amount of energy which might
have oeen put into it on charge.
872
THEORY AND GENERAL CHARACTERISTICS. 873
The foregoing is set forth by the following reyernble equAtton, which
shows the sction that takes pUoe:
charge
(1) PbO»+HsS04-PbSO« + HiO + 0
(2) Pb + H^04 " PbS04+H>
(8) - (1) + (2)-PbO,+Pb+2H^04-2Pb804 + 2H«0.
discharge
The fint equation shows the reactions which take place at the Doaitive
plate; the second shows those which occur at the negative: and tne sum
of these two, the third, is the combined effect and is the fundamental equa-
ticA of the storage battery. Reading from left to rii^t the leaotions are
those which take phMse on discharge, while read from rif^t to left the
reactions are those which take place on charge.
ClusBM iM Slectroljte. — The reveisible eciuation of the storage
batteiv shows that some of the SOs in the sulphuric add (which majr be
lookea on as being made up of HjO + 80s) goes into chemical combina^
tion with the plates on discharge, and a definite amount of SOs is abstracted
from the electrolyte from each ampere hour of discharge, and therefore the
concentration of the electrobrte decreases and is lower at the end of di»>
charge than at the beginning. The amount of SOs abstracted per 100
ampere hours is 296 grams, and therefore, with a given quantity of electro-
lyte and add density, the final dendty at the end of discharge after a cer-
tain number of ampere hours has been taken out, can be computed.
The formula for computing the quantity of electrolyte required, when
the initial and terminal dendties are given is
^ 1290- 10.53 d
irge.
I of H^iSOa in the electrolyte at the beginnina; of discharge,
of H18O4 in the electrolyte at the «id of mscharge.
X — number of ounces avoirdupois of dectrolarte per 100 ampere hours
of dischai
D ~ percentage
d — percentage
For discharge other than 100 ampere^ hours, multiply the computed
value of X by the actual discharge and divide by 100.
^y^ , ^^ 1290 + d(X- 10.53)^
And d ^
X
1290 - XD
10.63 - X'
S»1*luito« — Lead sulphate, which is a white substance, has no eon-
ducttvity whatever, and ii too much sulphate be allowed to form on
discharge, it is difficult to bring the battery plates back to thdr original
condition because the regenerating current cannot be made to flow through
the sulphated masses. If the plates are only partially sulphated, the high
conductivity of the active material with wmcn the sulphate is mixed will
afford a path for the current which can eadly reduce the sulphate back to
spon^ lead or lead peroxide.
This is one of the reasons why discharge should never go beyond the
point where the voltage per cell is 1.8 with normal outflowing current.
Chaa|pe \m Volvm^. — Another reason lies in the increase in volume
of the active material when converted into lead sulphate. If too much of the
active material be converted into lead sulphate, the increase in volume sets
up strains in the plates, tending to buckle them, and causes the active
material to crack or shed and uill away from the supporting grid, thus
redudng the amount of available active material, the capadty en the plates,
and shortening thdr life.
874 STORAGE BATTERIES.
▼•Itaipe* — The roltage of lead peroxide against eponge lead in dilute
sulphuric acid is about 2 volts, varyini^ with the concentration of the acid.
The actual voltage for any concentration may be computed by Streints'a
formula: E - l.wio + 0.917 (5-s). in which
E = E.M.F. of cell.
S "■ Specific gravity of the electrolyte.
• -" Specific gravity of water at the temperature of obeervation.
In practice it is generally assumed as 2.05 volts, this being the E.M.F.
on opoi circuit when the battery is fully charged; that is, both electrodes
being free from any lead sulphate. As the battery discharges, the voltage
gradually decreases, so that when the battery is nearly disohari^ its voltage
IS less than at the beginning of discharge. The reasons for this will appear
hereafter.
AppeaniMce of Plat«a. — The battery plates are distinguishable
both Dy their appearance and hardness, the peroxide plate being of a reddiah
brown or chocolate color and hard tike soapstone, and the sponge lead
plate is a grayish color, and can readily be cut into with the thumb nail.
Ite<|^HtreMieBta. — Neither lead sponge nor lead peroxide poosess any
mecbamcal strength, and therefore in order to make them into suitam
electrodes it is necessanr that they be attached to a supporting plate or
grid, and since lead is the only metal except the so-called noble metab"
which resists the action of sulphuric add, the supporting grid is always
made of it.
In order that a storage battery should work satisfactorily the current
must be distributed equally over the surface of the plate and pass throu^i.
practically, all the molecules of the aotive material both on cbar^ and
discharge, and it is essential that batteries be so designed as to attain this
condition; otherwise portions of the plate will be overworked and will dia-
integrate, while other portions may be left in good condition.
Tjp^m of Platoa.
In the production of battery plates there are three general methods:
One is known as the Plante process, which consists in chemically or
eleetrochemically forming sponge lead or lead peroxide directly on the
surface of a lead plate, this active material being produced from the lead of
theplate itself.
The second method consists in* taking certain oxides of lead, principally
litharge and red lead, and mechanically applying them to a previousQr
prepared leaden grid — generally under pressure — and afterwards reduiv
ing these oxides to sponn^ lead or lead peroxide.
The third method, which is not much used now, is to prepare pellets of
sponge lead or other lead compounds which may easily be reduced to
sponge lead, placing them in a mould, and casting the supporting grid
around them.
In the Plants type of battery the layer of active material produced ia
comparatively thin, and in order to obtain a sufficiently large quantity to
K've each plate a reasonable capacitor, it is necessary that the area exposed
i made as large as possible. Tlus is accomplished by some method
which raises grooves or webs in the plate, or by making up the plate of
narrow ribbons of lead, which are foloed backwards and forwards until an
electrode is finally produced, the thickness of which is e^ual to the width
of the lead ribbon, the length and breadth of the plate being anything that
mav be desirable.
The comparative value of these different types of batteries will be taken
up after discussion of various characteristics of batteries in operation.
Capiaclty. — The unit of storage battery capacity is the ampere hour,
that is, the ability to discharge one ampere continuously for one nour.
The capacity is dependent on the rate of discharge; tne temperature; the
quantity of active material present; the quantity of electrolyte in the cell,
and the exposed surface of the plate.
Theoretically, .135 ox. of active material per nefcative plate, with .156
OS. per positive or .201 oz. for both electrodes will, in the presence of suffi*
eient electrolyte, give a discharge of one ampere hour. In inactice about
^
TYPES OF PLATES.
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five timee thi« much, or 1.45 o». for both plates, ie required. The reason
of this is that the active material is not completely reduced, the discharge
being stopped before the point of xero voltage is reached, and the gradual
formation of sulphate as discharge phoceeds. tends to close up the pores
and prevent access of the electrolyte to the mass of active material.
The capacity increases with increase in temperature, being about I per
876
STORAGE BATTERIES.
cent for each degree Fahrenheit increase in temperature. Theoretically,
the ampere hour capacity of a battery should not vary with the curient
rate. If a battery oischarge continuouslv 100 amperes for 8 hours, giving
800 ampere hours at this rate, theoretically it should di^harge 800 amperes
for one hour. As a matter of fact, however, the ampere hour capacity of
a battery decreases rapidly with increase of rate of current flow. The
reason for this decrease m capacity is due to several causes, the most impor-
tant one being that as discharge proceeds, the active material begins to
turn into leaa sulphate. The volume of the lead sulphate is very much
greater than the volume of the active material from which it is fonned, and
since the action takes place most rapidly on the surface of the plates where
they are in contact with the electrobrte, the formation of the sulphate also
takee place most rapidly at the sunaoe, and this increase of volume tends
to fill up the pores of Uie plate and prevent access of the electrolyte to the
active material which lies beyond this shielding layer. If the discharge
;^ rate be very rapid, the masking layer of sulphate is raindly built up. and
«^ the shielding effect takes place more quickly. In a batteiy discharged at a
^ low rate the formation of this sulphate layer is so slow that the electrolyte
can reach the innermost portions of the porous active material, the chemi-
cal action takes place more thoroui^ily, and a greater amount of current
can therefore 'be taken out.
Curve No. 1 shown in Fig. 1 gives the variations in capacity with vaiving
rates of discharge in percentages of the ei|^t-hour rate, and curve No. 2
shows the increase in amperes output with increased discharge rates.
Thus if a battery have a capacity of 400 ampere hours, it will discharge
50 amperes continuously for eii^t hours. If the total capacity be taken
out in one hour, the discharge rate will be 200 amperes, and the ampere
hours will be 200, this being 50 per cent of the eight-hour rate as indicated
by the curve. If the ampere hour capacity of the battery at the eig^t-hour
rate be known, its capacity at any other rate can be determined fiom this
curve, or if its capacity at any rate be known its capacity at the ei^t-hour
rate can be also deteimined. The curve is an average, and applies approxi-
mately^ to nearly any type of battery, although different characters of
batteries will give different curves, but none of them will depart materially
from that shown in the figure.
Volteff« Variation.
As stated, the voltage depmds on the character of the electrodes and
the density of the electrolyte. The available potential at the battery ter-
minals is further dependent on the internal resistance of the cell. These
facts explain the drop in voltage as discharge proceeds, as indicated by the
eurves in Fig. 2.
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ELECTROLYTE. 877
The electrodes gradually change from pure active material to a mixture
of active material and sulphate; the formation of the sulphate increases the
resistance front the surface of the dectrodes to their conducting srid,
thereby increasing the internal resistance, and the surface layer of sulpnate
prevents access of electrolyte to the interior poree of the active material,
and the small amount of electrolyte imprisoned in these pores has its SOs
rapidly abstracted from it, greatly reducing its concentration and there-
fore the voltage of the cell. To this cause nearly all of the fall in voltage
may be attributed.
Slectrolyto.
The conductivity of the electrolyte varies with the density of the acid,
being a minimum when 30 or 35 per cent of the mixture is acid, and
increasing if a greater or less percentage of acid be pres^it.
Parts of the plate surface may do more than their share of the work if
the plates be very long and the containing tanks deep, this condition aris-
ing from a difference in the density of the electrolyte at the top and bottom
of such tanks. The containing ouls should therefore never be deeper than
20 inches, unless some artificial means of acid circulation be used, such as
compressed air introduced into the bottom of the tank through small rubber
tubes. With such circulation the electrolyte density is maintained con-
stant in different portions of the tank, and the plates will then be worked
at equal current densities over their entire surfaces.
Conductivity also changes with the temperature, being greater for
increase of temperature. The table on page 1229 under caption "Electro-
chemistry" shows the changes in electrolyte resistance with variations in
density and temperature.
The density of electrolyte in storage batteries should never exceed 1.200
when the batteries are fully chargea, and there should be ten pounds or
more of electrolyte per 100 ampere hours of battery capacity on a basis of
the ei|(ht-hour rating. The final density at the end of discharge with this
quantity of add ana 1.200 initial density, will be about 1.134.
In motor car batteries about four pounds of electrols^e per 100 ampere
hours is sufficient, and because of the small amount of acid present the
initial density must be higher. If the initial density be 1.265 at bednning of
discharge it will, with this amoimt of acid, fall to about 1.137 at the end of
discharge. Since there is a definite change in density for a given amount
of discharge taken from a cell, the density of the electrolyte is one of the
best indications of the state of charge of a battery, provided, of course,
that no internal discharge, due to loo&l action, takes place. If, when the
cell is charged, it shows a density of 1.200 and when discharged 1.130, the
difference, .07, represoits the total change. If at any time the density is
1.165, just one half the amount of capacity has been taken from the cell.
In order that these observations mav be reliable, however, it is necessary
to stir the electrolyte well, so that the density is the same all through the
tank: also if the oischarge has taken place at a high rate, the cell must
stand for an hour or more before the electrolyte will completely diffuse so
that the density readings are correct.
The electrolyte must be made of either distilled or rain water, mixed
with pure brimstone add. Ordinary dty or well water will, in all prob-
ability, ruin the batteries, and pyrites aad will most certainly do so.
The electrolyte should always oe tested to discover if harmful impurities
are present, which are platinum, iron, chlorine, nitrates, copper and acetic
add.
The tests for these are as follows:
Plattnnm. — A complete test for this substance can only be made by
an experienced chemist with proper appliances. A good rough^ test for
traces of platinum is to pour electrolyte into a cell and note if gassing takes
place on open circuit. If it does, and continues for some time, it is an
indication of the presence of platinum, and the suspected electrolyte should
then be sent to a chemist for analysis. Never use chemically pure sul-
phuric add which has been refined in platinum stills.
TroM* — Take a sample of the electrolyte and neutralise with ammonia.
Boil a small portion with hydroijgen peroxide, which process will change
whatever iron may be preeent mto the ferric state. Add ammonia of
878
STORAGE BATTERIES.
» V
caustic potash solution until the mixture becomes alkaline. Iron will be
indicated by a brownish red precipitate which will then form.
CliloiiMe. — Take a small sample of the electrolyte, add a few dn>ps of
nitcate of silver solution of concentration of twenty to one. A white pro-
dpitate will indicate chlorine. This precipitate will be redissolved h^
addition of ammonia, and can be re-precipitated by the addition of nitrie
acid.
lVltratea« — Place some of the dectrolyte in a test tube, and add strong
ferrous sulphate solution. Then carefully pour down the aids of the tube
a small amount of chemically pure concentrated sulphuric acid, so that it
forms a layer on top of the Aquid. If nitric add be present it will be
shown by a stratum of brown color, which will form between the eleetn>-
lyte and concentrated add.
Acetic Acfld. — Add ammonia to a sample of electrolyte until it beoomee
neutral, then add ferric chloride (FejCle). A red color will indicate tlw
presence of acetic add, which may be confined by the addition of hydro-
chloric add. which will bleach the mixture.
IiOCaI ActlOM* — Certain metallic impurities present in the electrolyte
may be, on chance, carried over to the negative plate, and the hydrpfen
there evolved wiU turn these impurities into pure metal. The condition
then exists of the sponge lead plate having a different metal attached to
it, and in electrical connection therewith^ and the two immersed in elec-
trolyte. If the voltage of such a couple is suffidently hi|^ to decompoae
the dectrolyte, current will be^n to flow, the whole acting as a short-
drcuited battery at the negative plate. This discharges the negative,
dther wholly or partially, according to the amount of metallic impurities
which may be carried over, and it is then not in a proper condition to
discharge m company with the positive plate when it is desired to take
current from the ceU. If this local action continues for some time the
negative plate may be so far discharged that it will sulphate, and finally
become worthless.
Cadmlam Teat.
The condition of the negative and positive plates can best be^ Mon^
tained by measuring the voltage between the plate under examination
and a small test electrode of cacmuunu This cacbnium should be covered
:.iO
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FIG. 8.
with rubber, perforated so that the test piece cannot come in contact with
any of the battery plates or connections, thou^ the dectrolyte may freely
penetrate to it.
When a cell is fully charged, showing a voltage of 2.5, the voltagis
between the negative plate and the cadmium should oe from .16 to .2 voft.
When disch&n^ takes place, this voltage gradually reaches aero, after
which a potential begins to rise in the opponte direction, gradually increas-
ing with discharge. When the voltage^ after pasdng through sero. reaches
a value of .25 volt, the -full amount of discharge has been taken from the
negative plate, and the current should be cut off regardless of the potential
of the cell.
Figure 3 shows the way in which the potential between the negative
EFFICIENCY. 879
plate and tbe CMbnium chances. The cadmium undeiv>iniK no discharge
does not change, and its line of potential is therefore horixontal and
unchanging, as indicated. The negative plate, however, is discharging,
and its potential decreases so that, though it begins to discharge at a poten-
tial of .18 volt above the cadmium, it soon reaches a point at which it is
the same as the cadmium, the voltage between them then being sero. As
the potential of the n^piitive falls further, a potential begins again to
appear between the two, but, as is obvious, it is in the reverse direction*
as the potential of the negative plate is now lower than that of the positive.
On charge, the voltage between the cadmium and the negative plate
should be brought up to at least .17, even if continued overcharge after the
cell has reached 2.6 volts is necessary to do it.
Batteries are so designed that the negative plates work through their
proper range of potential with normal change in the cell E.M.F., but over-
sulphation, reduction in amount of active material, or, most of all, local
action, will destroy this balance, and these cadmium tests are useful in
keeping watch over the condition of batteries in service.
PolArlsattoB.
If the voltage of a battery on open circuit be a given amount, say 2
-volts, and charging current iff sent mto it, it would be natural to assume
that the potential rise at the battery termmals would be equal to the drop
due to the internal resistance of the battery. It is found, however, to be
very much gnaXer than this amount — the actual internal reedstance of
large cells being practically negligible. This increase in drop, when cur-
rent passes throus^ a cell, comes from a phenomenon known as polariza-
tion, which is, in effect, the production of a counter E.M.F. which opposes
the flow of current, and which always takes place whenever current passes
from one electrode to another inunersed in an electrolyte. This effect also
opposes the flow of discharging current, and causes the voltage drop at the
cell terminals, which is observable when current is taken from a oattery.
The principal polarising agent is hydrogen, which may be considered as
an electro-positive element. It always forms at the negative electrode
and sets up an E.M.F. opposing current flow.
In cells of the same tyi>e the drop at any given time rate of charge or
discharge is the same.
Vli« Volta(r« Itrop in cells of a given type is independent of the
sue of the coll, out varies with the state of battery charge and the rate
of dischar^. This drop is also fairly constant for various types of cells.
The following table fpves the Call or rise in voltage from the open circuit
E.M.F. when discharge or charge takes plaoe:
6
4
3
2
1
The efficiency of the storage battery, similarly to that of any other
device, is the ratio of the watts output to the watts input. If current be
taken out at a high rate, and a resulting small .capacity be obtained, it
does not follow that the efficiency has been lowered correspondingly, as
it will be found that the amount of current required for succeedins charKe
will not be so great as if a lower rate of discharge had been used, and a
peater amount of energy taken from the battery. In other words, there
IS a relation between the amount of energy derived on discharge and the
amount of energy^ required on subsequent charge to bring the battery
back to the condition at which the discharge began. The efTiciency of
batteries which discharge only a few moments and immediately after
receive charge, that is, in which the charge and discharge fluctuate rapidly.
{
•. * *
. . .065
. . .09
. . .11
. . .14
. . .2
BflctetMCj.
880 STORAGE BATTERIES.
and the net amount discharged from the battery in an interval of time ia
small, is about 00 to 02 per cent. Where used for power storage, a lone
continuous charge being sent into the battery and foUowed by a Ions con-
tinuous discharge, the efficiency is from 75 to 80 per cent.
The losses in a battery are made up of the PR, and the gassing at the end
of charge, in which the constituent gases which are released by the action
of the electric current do no chemical work on the electrodes, but eeci^M
into the air, the eneivy required for this dissociation betnn^ lost. There is
also the further loss due to the counter E.M.F. of polarisation, as has been
explained.
GomparlaoB of PlaMt* and Pasted
Klectrodea.
Of the two types of cells mentioned, the Plants and the pcMted, each has
its particular place, and one is more suitable than the other for its partic-
ular class of work.
The paBted negative plate is. in general, the best ty|>e for nearly every
class ojf work. Patted positive plates are necessary in batteries where
light weight is required, such as in automobile and train lighting batteries.
They are also suitable for battery plants which receive long charge, store
the energy and discharge over a considerable length of time, such as resi-
dence and isolated plants, and central lighting stations. The PlanU posi-
tive is most suited to those conditions where the battery discharge takes
place for short intervals at very high rates, such as regulation of railway
and elevator loads, and also when prolonged overcharge is likely to occur
frequently.
Charrlac*.
In charging the voltage gradually rises, as shown by the upper curve in
Fig. 2, until about 2.5 volts are reached, when, at both the positive and
negative plates, gases are rapidly released. Charge should alwa^ be
continued until both i>late8 gas freely. Full charge will also be indicated
by the electrolj'te density rising to its proper value.
The best way to charge is to send in current rapidly at the be^^nning
and gradually decrease it until at the end of charge the current flow is very
small. For mstance, in charging a 1,000 ainpere hour cell for e!|^t hours,
the average rate of flow is 125 amperes. The proper rates at which to
charge this cell would be
250 amperes for 1 hour
200 " " 1 "
160 " " 3 "
76 " •* 1 *•
26 •• " 1 ••
For rapid charging, when a battery has to be charged in four hours, the
current should vary as follows:
40 per cent of total 1st hour !
25 * 2d *• I
20 •• " •* 3d " I
15 4th " i
I
For quick charging in three hours the rates should be:
50 per cent 1st hour
33J •• •• 2d '•
16J •• •• 3d "
BATTERY TROUBLES. 881
Whatever the rapidity of ehartn, never send a heavy current into a battery
toward the end of charge. Tne rapid ratee can only be lued during the
early part of charge.
In case of lorn of electrolyte from the celb from evaporation or sprasring,
add only pure water to maintain ita level, as the addition of normal elec-
trolyte will gradually increase the density of that in the cells, because the
added liquid merely takes the place of that which has been carried off as
gas or lost from evaporation, which, in either case, is pure water only. High
electxolsrte densities tend to accentuate all the troubles that can befall a
batteiy, and accelerate the formation of sulphate. The water should be
introduced throuidi a rubber hose or lead pipe extending nearly to the
bottom of the ceU, so that it will diffuse and mix with the dectrolyte. If
the water be poured in. it, b«ng lifter than the electrolyte, will float and
take a long time to diffuse with the liquid in the celL
To take a batteiy out of commission it should first be fully charged,
then given a good overcharge, and then. discharged down to 1.7 volts per
cell in the electrolyte, immemately after which the electrolyte should be
drawn off, and either distilled or rain water put in the cells. The dis-
charge should then be continued until the volta^ comes down practically
to sero. In most cases it is necessary to short-circuit the cells m order to
get them down nearly to xero with pure water as the electrolyte. Dis-
charging^ them in the water has no injurious effect, however, as no sulphate
can form. Upon complete discharge the water should be poured out of
the cells, and the plates thoroughly washed, generally by nmning water
continuously through the cells. All water is then drawn offhand the plates
mi^ then stand for any length of time without injuiy. When the bat-
twies are again to be used, it is only neoessaty to pour in the electrolyte
and give a long overcharge.
B»ttei7 Tronblea.
The princi|>al troubles which are encountered in battery operation are
loss of capacity, buckling, shedding of active material, sulphadon and
loss of voltage.
Mtoam of Capactt^ usuallsr comes from dograng of the pores in the plate
with sulphate which is not visible to the eyebecause the surface of the
plate is maintained in proper condition but the interior portions of the
active material have not beien thoroughly reduced. This condition can be
remedied by prolonged overcharge at low current rates, say about one-
fourth the normal eight-hour chaiging rate.
Miomm of Active Material will also reduce the capacity of a plate,
and this takes place continuously, but slowly, in every storage battery, ana
may be considered as the normal depreciation. If the battery be over-
worked, however, and especially if discharge be carried too far, the amount
of sulphate formed will so expand the active material as to cause it to crack
or shed off veiy rapidly.
SBdcliag*. — Unoer the action of unequal exiNinsion of the two sides
of the plate, or certain portions of the plate, the strains may distort it and
cause it to assume a buckled shai^, that is. bent so one side is concave and
the other convex. This is due, m every case, to over-discharge on either
the whole or some portion of the plate, and consequent over-sulphation and
over-expansion. In certain battery plates, which are designed to allow this
expansion, budding cannot take place, but in most of them the active
material is on an unexpanding framework, and over-discharge is therefore
to be avoided.
ftalplufttlom* — > This is practically the cause of every storage battery
trouble, and can only be avoided by stopping the discharge before the
voltage of the cells has fallen too low, namely, at 1.3 volts per cell, with
normal discharge current flowing, and by occasional boiling, that is, over-
eharge which should be given at intervab of about three or four weeks.
U. N
882 STORAQE BATTERIES.
In giving thie ovcroharge the battery should be fully charged at noimal
rates until it shows about 2.6 volts per cell. The current should then be
decreased to about one-half its normal eijdit-hour rate, and the charge
continued until the cells show about 2.65 volts, and about twraty minutes
after this potential is reached. This will effectually reduce any aolphate
which may have accumulated in the pores of the aotive material. A bat-
tery should never be allowed to stand idle or uncharged after disobarga^
as the plates will sulphate very rapidly. A charge should be started immo>
diately after discharge, or as soon thereafter as poesible.
I«oaa of VoltaM. — > It will frequently be found that one or more of a
number of oeUs willshow a lower voltage than the others. This generally
occurs because of Von in capoctiv. ao that a cell having this lower d^padty,
and in seriee with the main battery, would diachargie the same amount as
the other cells having a higher capacity, and in this way its voltace would
drop more raiHdly and always ba lower than that of the other cells on
discharge.
There are two classes of stotage battery tests. One Is to determine
whether a battery which has been installed meets the conditions of the
specifications; the other is to determine all the constants of a battery as
compared with others on the market, either for purposes of improving the
product of the factory or determining its oommeraalvalue.
The first class of tests will not be gone into here, as they will be indicated
by the conditions of the contract and 8i>ecifications. In the second clasa
of tests the following are the points to be determined:
1. Weiii^t of complete odl.
2. Weight of the separate component parts, namely, elemeata, eleetro-
Isrte, separators and containing cell.
3. Dimensions of component parts of the odl.
4. Rates of charge, maximum and normal.
6. Rates of dischaige, maximum and normal.
6. Capacity at low, nonnal and rapid diecharge rates.
7. Voltage curves of charge and discharge.
8. Internal vvrtMoX resistance.
0. Variation in density of electrolyte.
10. Loes on charge with time.
These are all determined by test and observation, and from them are
dleduced:
11. Charge and discharge rates per square foot of positive plate suifaoe.
12. Charge and discharge rates per pound.
^a) of complete odl.
(6) of element.
18. Capacity per pound.
(a) of complete cell.
(6) of element.
14. Efficiency at various charge and discharge rates.
ITeirM of Complete C«U aad CoMpoaesi
The weii^t of complete cell is of course found by means of the
and in order to determine the weight of the component imrts theel.^^
should be partly discharged, then removed from the dectrolyte and dried
with blotting paper, after which they are weighed. Do not keep the nega-
tive plates in the air any longer than necessary. The weight of the elec-
trolyte is equal to the total weight, less that of the elements and jar.
INTERNAL YIRTUAb BE8ISTANCB.
883
These are detennined by usual
gfe dismantied for weighing, and
CUfmiNT tUPPLV
FOR CHARQINO f^
vwww.^
OiaCHARQINO REtWTANCE
Tig. 4.
and V ia a low-reading voltmeter
measurementfl at the time when the oelb
should include dimensions of sex)arator8.
hdfl^t of lower edce of plate above bottom
of jar, clearances between adjacent plates
and between interior of jar and plates.
Also area of plate surfaces and of con-
ducting lU0. This latter for the puipoee
of determining if current densities are
within usual practice, namely, about 160
amperes per square mch. The cell may
then be reassembled, given a prolonged
overcharge, and connected up for testing.
CoBBectiona tor Teattnar. — Re-
ferring to Fig. 4, R is an adjustable resist-
ance oy means of which the current to
the battery nuiy be kept constant. B is
the cell under test; S a D.P.D.T. switch;
Rt a variable resistance through which
discharge takes place and is maintained
at a constant value; A is a two-way
reading ampere meter which measures
both mflowmg and outflowing current
acroflp the cell terminals.
The charging rates are usually given by the manufacturers, but if with-
out this data, six amperes per square foot of positive plate surface may be
taken as a trial rate, and ttter a few charges and discharges may be deter-
mined by the length of time required to fully charge or discharge the cell,
llie eight hour is the standard normal rate. Hie maximum charge and
diecharge rates are usually taken as the one hour rate, althou^ the current
flow should never be so rapid on charge as to heat the cell more than 25^ F.
above aoirounding atmosphere, or cause excessive gawsing
Cai^ctty at Varioas ]Macluurf« Ratoa.
These are determined on taking out a constant current <m discharge at
say, the eight hour, the four hour and the maximum rate, whatever the
latter may be, and noting the length of time during which this discharge
continues, the battery having been charged up to 2.5 volts before beginning
discharBB, and being out off when a voltage of 1.8 is reached, except in the
case of the maximum rate, when the voltage can be carried down to 1.78.
Since the capacity will change with temperature, it is necessary to note
the temperature, and keep it constant throui^ any one detennination.
Voltage Carrea.
During charse and discharge — both of which should take place at the
constant rate for testing — frequent obaervations should be made of the
voltage across the cell terminals. From this the regular charge and dis-
charge curves are plotted with voltages as ordinates and time as absdsss.
latonial VIrtaal Itoalstaaco.
There are many methods of determining the internal ohmie resistance of a
oell, but this has no bearing whatever on oractice. Furthermore, it is not
eonstant, but changes with the state of charge and discharge. What an
cni^neer requires to know, is the drop at various discharge rates due to
wfaa««w iBleRial elleeta may take place. The net result ofaD the factors.
V
'I
884 STORAGE BATTERIES.
namdy, intenuU ohmio resistance, polariiation, increase in nonnal int«nial
ohmic resistance, due to the passage of figses throuch the electrol^^, etc.,
are all included in the term, " Virtual Resistance/' To determine this,
note ^e voltage of the oeU on open circuit. Then dose the diaoha»
switch quickly, allowing a heavy discharge current to flow. The volt-
meter wul immediately indicate a lower value than when the battery was
open circuited. Read the voltmeter within four aeponds after dosins the
discharge switch. The difference between the discharge voltage and the
open-drcuit voltage, divided by the amperes flowing on discharge, is equal
to the virtual internal resistance. Severn! tests should be made at different
rat«e of discharge, and also several tests in which charginfr current is sent
into the battery; the rise in voltage above that on open circuit noted, and
the difference between the open circuit and the observed charging voltage,
divided by the inflowing current^ will give the internal virtual resistance.
Owing to the small changes it is difficult to get accurate results, and the
average of a number of testa both on charge and discbarge should be taken
as the actual value.
ITsirimUam la J^eaaity of Slectroljrte.
This should be noted as discharge proceeds, by reading the speeifio
gravity on a regular flat bulb hydrometer immersed in the cell itseu. At
the end of charge the hydrometer should be allowed to stand in the acid
for about four hours before taking the final spedfic gravity in order to
allow the dilute add in the interior pores to mingle with the main body of
add in the jar. If the gravity be taken without allowing this time to
elapse it will be found higber than the actual gravity will be after complete
diffusion.
IfOea of Cliaiv« wfttli XiMie.
This is determined by subjecting a battery to severaJ crdes of ehainee
and discharge, untU its capadty becomes constant at the giv«i rate.
Knowing this capadty, if the cdl be fully charged and set aside for several
da3^ and then discharf^ at the normal rate, the difference between its
capadty when immediately discharged, and that after the interval of
time has elapsed, shows the loss which may occur from leakage or local
action. The cells should be kept perfectly dry and well insulated to
prevent any leakage whatever when set aside.
These are computed from a knowledge of the dimendona and the charg-
ing rates, determined during the test.
BfldeBcy at Varfoaa Chaise aad IHechaiv^ liataa*
Effidency is determined at the various charge and discharge rates by
dividing the output on discharge by the input on charge. In all cases the
diacharge should precede the diarge against which the ratio is to be taken,
and in every case the cell should be brought back to its ori^nal condition
on charge. In taking effidency, if a charge be given and a chscharge folk>w
it, to compare these would give no reliable results, as it is the charge whicii
succeeds a given discharge that bears the proper relation to it.
Failure to recognise this fact has been the cause of the extraor<fiiiary
results which certain tests have shown, in which the effidency haa been
over 100 per cent, though in most cases the erroneous method of comparing
a charge with its succeeding discharge will give a residt below the actual
effidency of the battery.
Erectloa of JBattorfoa*
Storage batteries should always be installed in a oool room, which is
well ventilated. The floor should be of cement, tilee or brioks, and it
should slopNB slightly to one or more drains, so that water or electrolyte
which is spilled or leaks may easily run off and the floor be kept dry.
ERECTION OF BATTEBIES.
885
An ezpoflod iron work should be covered with some cood acid-proof
pttint, and all expooed copper should have a coating of lead or tin, to pre-
vent the corrosive action of acid fulnes.
Provision should be made for easy and thorough inspection of the cells.
Thery should therefore be accessible, and hand uunpe connected to long,
fleziDle conductors provided so that each cell may be inspected.
In the installation of large station batteries consisting of a number of
larfpe plates in lead lined tanks, it is usual to set these on 4X6 inch stringers
which run underneath a row of cells. Four or more porcelain insulators
are placed between the stringers and the cells, and in many cases it is usual
to doubly insulate the cells by putting under each one a wooden fram^
work which is the sise of the bottom of the cell, above the strinsers, resting
it on insulators which aro supported on the stringers. The cell rests on a
second set of insulators which are in turn supported by the framework.
The number of insulators depeada on the sise and weight of the cell to be
supported. The positive plates in each cell ara connected to the negative
plates in the adjacent cell by bundng each of the olates separately to the
feaden bus bar, as shown in Fig. 6. In the ■maUer siies of oells which
MEO.- MATE LI
BURMEO
XMNT
PLATE LU«
SURNBO tfoticr
MEa PLATE LUa
,SUS BAS
OLASs supposrr plate
LEAD LININO LEAD LJNINO
WOOD TANK WOOD TANK
Fio. 6.
have lead lined tanks, thev aro generally set on a framework from twenty
to twenty-four inches high and rest upon four insulators. The plates of
each cell may be joined to those of the next succeeding cell either oy burn-
ing to a common bus bar, as above mentioned, or by boltini; together lead
straps which fonn the eell terminals, the bolts and nuts being, of course,
lead covered. If the containing vessels aro glass jars, it is usual to set
each of them in a shallow wcx>den box about li inches deep and filled with
fiiie, dry^ sand. The glass ceil beds itself in this sand, gi\nng an equal
distribution of pressure over the bottom of the Jar, and the sand also catches
and absorbs such electrolsrte as may be spilled or sprayed out with escap-
ing gases. Each sand tray, as these are termed, rests upon four porcelain
insulators, and the cells are placed on a framework in one or two tiers, as
may be desired. Fig. 6 shows this method of installing.
l««»d BvmlniT; — The hydrogen flame has the special property of not
osdising, or otherwise soiling the lead, and is therefore used for melting
toother two lead surfaces, notably that between cells and the sheet lead
limng of the tanks.
Hydrogen gas is generated in a vessel from sulphuric add and sine. The
gas is couected and passed through a water bottle to a burner, where it is
mixed with air that has been forced into the burner by a pump or bellows,
the mixture bdnf ignited for the welding.
, The use of^ this burner reauires some skill and practice, especially in
joimng the edm of sheet lead, as it is very apt to bum away. All plate
tenmnals, and all lead connections of any kind, must be scraped clean
baore connecting up.
886
STOBAQE BATTEBIBS.
lt^:fe^^viJ^<iy^;^^#^^^y^l#| [lli;v^)^:x?jiw»Aaifei^sgS]
! 8AN0 TRAY
aANQ TRAY
Fia. C.
•f llatterie*.
The principal uses are :
(1) For propelling electrically driven motor can.
(2) For railway train lighting.
(3) As a subetitute for the ordinary primary battery in tdephone and
To cany the load peak on a supply system.
telegraph work.
T4) Tocarrj .. , .
(5) To carry the entire load during the periods of light demand, the
generating equipment being shut down.
(6) To regulate the load on systems where the d«nand fluctuates
widely.
(7) To act as an equalizer on three-wire systems in which the geoei^
ators are connected across the outsides of the system and gjve a oorre-
sponding voltage.
(8) To reduoe the amount of copper required for systems supplying
variable loads.
(9) To insure continuous service.
(10) As auxiliaries to exciter dynamos in large alternating currant
stations. •
(11) Combinations of any of above from (4) to (8).
The first three applications involve no special engineering knowledgie.
(4) In case of a supply nratem on which the load rises greatly during
certain hours^ of the day. as shown by the load curve A, B,C, D, i?, F, <7, W,
in Fig. 7, it is often advisable to install a batterv to receive charge during
the period of light load, as shown by the shaded area in whidi toe heavy
curve is the demand on the station and the light curve, the load on the
generating equipment, the difference going into the Imttery; and to dis-
charge in parallel with the generators during the heavy output on peak
d, £, e, aa shown by the cross-hatched area. Such a oattery aaaiats to
USES OF BiTTEBIBS.
fc.
M
^
(^
^-1
^1
/i
^■€mmmmi--i i
N
! '
—
-
1 1 1 =1 s
1 /
i/
/
/
/
«(
i
M i 1 1 U L-
\ *
s
°
J
888 STOBAQB BATTERIES.
mainUin % nuaxailiy ooDcUtnt load on tha dynstngs. raduoea ths ooat of
th« nuarmtinc equipment, ard ia always rea*^ to take up any exene load
on tbe ayitem, aucb as may came frnrn a BUddcnly overrsst gky or atonn,
without the hw of time neoeaury to fire up addltloaal boilers and start
sdditioDa] nnsjaes, aa would tw tlie cssa if tb« entite k«d w«re oanied by
genenMiuc machinaty.
(S) After tbe peak disehati^ is mdad aod Uw load on tb* oyatam
*— '-iw tbe teoPTStor capacity, the batteiiea may be fully charasd
UKht. and tba cnlire plant shut down during tha period ol
s may be fully
, n during tha pn
Thii is also indicated in Fis. 7,
charge, while the croas-natchcd area h, k, vt, n, indicates battery uscharge.
If the battery in large enough to do this, (he oust of the fuel and thg d«i>re-
attendimtn only ftr« reniuired insttiuj of three.
Ifl) Id oaxe of a system on which the load auetuatea r^dly and
between wide liiQite, auch ( ... . ' -.- . . . , . i ^l_ ,
of load diasiam will be as
no.i.
o I.OOOampoea, thont]i the mtregt load takoi <r
r the geneimting equipn
s, will hare tobeof aufl
._..g machinery wiU be n
and Btrains due to the nudden loads. ''^- '-
uch more than it would be if the i
reflating battery b
if the syatem be without a battery the genermttng equipmeot. includinB
_. 1 — . . 1 : ml .- I 1 _..iB_:g„, e«II«dtT
iMNbSeoted
he fud con-
oould work
4idy load. If a reflating battery be used, the fleneratiue BQuip-
id onhr be ETMC enou!^ to supply the avtmgt load, as the batterr
irb aJl fluctuBiiona. When the current required to supply ths
elitemiU circuit !b RmaEI, tbe additional anioutitH etijqilied by a BenBrator
workinc under conutaiit load, will so into the batteiy and be stored th^
sa charRe. Wheo the eilenia] load exceeda the sveraKe Kenentor out-
put, the eiceas in fumiM}ied by (he battery disoharge.
liiuB tbe bsttery maiatBina a oonstsni load on (he naeistJnE equipman[
regardless of tbe variatioDS in the eTtemal load, and the attendant advan-
(ofCe of fuel ecoDDm;^. normal duty only on moving maofainery. deoreasfld
depredadon and repairs, are realiied.
(7) In tbraa-wira lyatema. if the Kenentors dve a vollaa* eqittl ta tliat
between the outaide mains, some Fornix of equaliser are neoesaary toprevcBt
tbe unbalancins which may lake place. U a battwy be comMoMuros
tha outadaa wiUi a aufReient number of oella in Mnw to giva u BJI.F.
METHODS OP CONTROLLING DISCHARGE. 889
equal to that of the system, and the neutral be connected to the middle of
the battery, any excess of current flow^ on one side of the system, 'will be
supplied 1^ discharge from the half of the battery connected across that
outside and the neutral, while the half of the battery on the other side
mill receive an equivideot amount of charge. This is a widelv used
arrangement, as all the other advantages of storage batteries are obtained
in addition to the balancing effect.
(8) In cases where cunmt is transmitted over a considerable distance,
and the load varies either at different periods of the day, such as a lighting
load, 'or rapidly, as a railway load, a storage battery located far away
from the station, near the iioint where the load comes on the system, may
be made to maintain the voltage at periods of heavy load when the feeder
droi> would be excessive, and the useful potential too low for satisfactory
service. This is accomplished by the discharge of the battery when the
heavy load oomes on, reducing the amount of current transmitted and
therefore the drop. The battery is charged during the time of light load
when sufficient current is transmitted to supply the load, and also charge
the battery. In other words, the battery equsJises the load over the line,
causing the continuous flow of average current, and reducing the cost of
feed or copper.
In certain classes of rapidly fluctuating loads this effect is automatic
and produced by slifi^t changes in line drop, with small changes in the
load over the line.
(9) To insure continuous operation of any electrical plant a storage
battery is necessary. No matter what may happen to the generating
part of an equipment, if a storage battery be coimected to the mtem it
will immediate take on the load and carry it a suflicient length of time to
enable any quick repairs to be made and the machinery a^n started up.
(10) In large central stations where alternating current is generated and
distributed to substations, and a large territory is dependent on the station
supply, the failure of an exciting dynamo would cause a shut-down of pos-
sibly several minutes, which would be a serious mishap. To insure agamst
this a storage battery is connected directly across the exdter bus bars. It
does no work and is never of any real service unless failure of an exciter
takes place, in which case the alternator field excitation is taken up
without a break or intenral. The insurance against stoppage, even for a
nxoment, by means of the stora^ battery, is so thoroui^Iy demonstrated
that nearly all the large alternating current stations have added this equip-
ment to thdr exciter systems.
(11) O>mbinations of (4) to (9) inclusve ran be in part ^ected by a
sinfl^e battery, such as regulation of fluctuating load, discharging on peaks
and carrying the night load alone, or equalizing on a three-wire system,
carrying peaks on both sides of the system, and also carrying the light
load alone. Many other combinations will suggest themselves to the
engineer as the conditions to be met may fequire.
Rfetb^Wla of CoBtrolltas' IHacharyv.
In Fl^ 2 is shown the change in voltage of a cell when charging and
diseharging at the normal rate. In order to compensate for this variation.
BO that the E.H.F. supplied to tiie discharsing arcuit may be maintained
constant or varied at will to meet external load conditions, the following
methods of control are used:
Jl) The number of cdls in series may be altered by means of suitable
tehing mechanism.
(2) Counter oells, or cells oonneoted in opposition to the main battery.
may be included in the discharging circuit and the desired voltage obtained
by varying the number of counter cells in this dronit.
(3) A variable resistance may be interposed in tbe main drcuit to regu-
late the discharge.
(4) A dynamo-electric machine, termed a "booster,*' having its arma-
ture in series with the battery drcuit, its field bdng variable at will as to
either direction or magnitude, may be employed.
If any of the fixvt tovee methods be employed, the total number of cells
890
STORAGE BATTERIES.
compomng a batteiy must be such that at the end of discharge, mth
normal outflowing current, the sum of the voltages of all ceUa in series is
equal to the voltage to be maintained on the supply circuit.
When discharging at normal rate, it is usual to stop discharge when ths
E.M.F. per cell has dropped to 1^8 volts.
■ad CelU
Swfttchea.
^|i|l|i|<|iii|i|i|i|i
Fio. 9.
As shown in Fig. 2 the E.M.F. at the beginning of discharge is 2.15
volts, and at this point on the discharge curve only 51 cells would be
required to give 110 volts; as discharge continues and the E.M.F. falls, the
number ci odls in series must
be increased aocordin^y, and at
the end of discharge, when the
cell volta^ is 1.8, 61 oells are
required m series to supplv a
llO-volt system, 10 of them
being end or reserve cells. The
whole 61 celb would be con-
nected in a single series, a
conductor being connected to
each of the ten aid cells and to
suitabto contacts on an end cell
switch.
The voltage across the (fis-
charging circuit will be diepen-
dent upon the number of celb
included in the circuit.
Figure 0 shows an arrangement of cells, all connected in series, a portion
of these being end cells; the voltage when the moving arm M is in the posi-
tion shown by the full lines will be that due to all the cells in the main bat'
tery, plus the voltage of the two end odUs included by the arm. If now
the arm be moved to the position shown in the dotted lines, the voltage
across the mains L will be increased by the addi-
tion of the end ceUs 4 and 5. In switching from
one end cell point to another the discharging
circuit must not be opened, neither must the
movinfi; arm touch one contact before leaving
the adjacent one, since the jdfning of two con-
tacts will short-circuit the cells connected
thereto.
In general, the form of switch for this pur-
pose IS essentially that shown in Fig. 10, waere
the moving arm is provided witn a small ad-
vance arm, the two being insulated from each
other but connected through the resistance X.
The npacings of the two arms and contacts are
such that when the main current carrying arm
is squarely on an end cell contact, the advance
or auxiliary arm touches no other contact, but
in passing from one point to the next, the ad-
vance brush reaches the contact towards which
the arm is moving, before the main brush leaves its contact; the reristance
X between the two points prevents short-circuiting, and the current to
the main circuit is never broken.
The conductors joining the end cells to the end cell switch oontaets must
be of the same sectional area as the conductors of the main circuit, for
when any end cell is in use the conductor connecting it to the switch
becomes a part of the main drctiit. 1000 amperes per square inch, when the
bcfctteiy is discharging at the two>hour rate, is good practice.
End cell switches of small capacity are made circular; the lat^ger sins
are, however, made horisontal in form, and both types may be either manu-
ally operated or motor driven.
End cell switches of large capacity are generally located as near the
battery room as possible, to avoid the cost of running the heavy coo-
mo oius
Fig. 10.
BOOSTEBS.
891
duotors, and when such switches are motor driven, the usual practice is to
oontrol their operation from the main switchboard.
Automatic end cell switches have been used more or lees abroad, but
have found little favor in this country. The controlling devices for such
•witches are so arranged as to make the switch automatically respond to
ohanges in the discharging circuit.
Coniiter K.]H.F. Cella.
Counter celts or counter electromotive-force cells are merely lead plates
in an electrohrte of dilute sulphuric acid; they have no capacity but set up
an opposing £.M.F. of approximately 2 volts per cell if current be passed
through, them.
In using these cells for controlling discharge, the total number of active
cells in the battery will be the same as if the method of end cell control had
been used. The oounter cells represent an increase in equipment, the
additional expense being 8 per cent or more.
Figure 11 shows the method of oounter cell control; these cells are con-
nected in opposition to the main battery, and conductors are run from each
of the oounter cells to points on a switdx similar to an end cell switch. At
the beginning of discharge aH the counter cells aie in circuit, acting in oppo-
sition to the main battery. As
discharge proceeds and the battery
voltage falls, the oounter cells are
gradually cut out of circuit.
Controlling discharge by oounter
oelhi is now nearly oosolete prac-
tice, and is scarcely ever to be
recommended; the only advantage
in this method of oontrol is that
the discharge throughout the l>at-
tery is uniform, but this fact alone
does not warrant the use of such
methods on account of the addi-
tional expense involved, and the
energy loss when discharging
against counter cells is the same
as if resistance had been interpoeed in the discharging circuit.
Fio. 11.
lKealat»nc« Control.
The discharge may be controlled by a variable resistance included in the
discharging circuit. This method
is not used unless the battery is
of small capacity and the cost of
energy low.
Figure 12 shows a diagram for
resistance control. In small
{>lants, where the available space
or battery auxiliaries is limited —
such conditions obtaining in bat-
teries for yacht lighting and the
like — the resistance oontrol has
some merit.
I i
il
II
II
L^VWWWN
I VAAMBUI
NUMTANOI
FIO.12.
A booster consists of a dsmamo electric machine, the annature of which
is in the battery circuit, its E.M.F. being added to or subtracted from that
of the battery to produce discharge or charge. This action of the booster,
i.e., the direction and magnitude of its armature E.M.F., may be auto-
matically or manually controlled.
892
STORAGE BATTERIES.
iUPPLY MAWS
nCLD
RHECCTAT
The Aliaat Booster.
As shown by the battery curves in fig. 2 the nuudmum voltage per tell
at the end of charge is 2.6 volts. As 61 cells are required for a battmy
operating on a 110-volt circuit, the total charging voltage requirad is
2.6 X 61 — 158.6 volts, or about 60 volts higher than the voltage of the
supply circuit, and to fully charge the batteiy this additional voltage
must be supplied by a booster or by an excess voltage in the «l<*ip|pti£
generator.
Figure 13 shows the diagram of a simple charging booster. Its armatme
should be wound for the normal chargmg current, and have a Tw^iw^^^p
voltage equal to the differenoe
between that of the supply
circuit and the ma-w^TY^^im
charging voltage. The field
is separately excited, cither
from the bus bars or the bat-
teiy, and the voltage at the
armature may be varied by
the field rheostat.
Instead of discharging
throu^ an end cell swit£
or resistance, the current
through the booster field may
be reversed and varied, so
that the E. M.F. of its arnw-
ture may oppose that of the
battery, this E.M.F. being
reduced as the batteiv v^
tage falls, the algebnue sum
of the booster and battery
£.M.F.'s being always equal
to that of the supply oirouit.
In this case, however, it is
usual to put in feww odls, the
available voltage being taken
as 2 volts per oelL On dis-
charge when the voltaim of
all cells in series is greater than that of the supply oirouit, the booster voltage
in equal to the excesa battery voltage over the supply circuit potential,
and in opposition to the battery voltage: when the battery voltage becomes
equal to that of the supply circuit the booster voltage is sero; when the
battery voltage falls below that of the supply circuit, the booster voltage
must then be in a direction to assist the battery, adding its voltage to
that of the battery.
END CELL swrrcN
009"
Fio. 13.
AutOBsatlc
In batteries which are used for regulation on fluctuating loads, the
changes from charge to disohar^ and vice vsrsa are so rapid that the slate
of battery charge changes but httle. The voltage of the batter^', however,
changes with these fluctuations, increasing with inflowing and decreasing
with outflowing current.
In this respect the storage battery has much the same characteristics as
a shunt wound generator: with increasing output the battery voltage falls,
due to the drop caused by internal resistance and polarisation; with
decreasing output the voltage rises for the same reasons.
These voltage changes are approximately proportional to the rate of
current flow causing tnem. The fluctuations coining with such raindity
and irregularity must be automatically compensated for by changes in
booster voltage, which vary both in direction and magnitude with the
direction and rate of current flow.
There are two generic types of automatic boosters, vis., the non-revexmUe
and the reversible.
BOOSTBBS.
893
In inatallatioiit where it 10 detiired to supply both an approadmatel^
eonatitat and a fluotuatina load, from the same generators — such condi-
tionB obtaininc in an office DuUding or hotel, where it is necessary to supply
UjBhta and elevators from the same source of supply —- the ^fluctuations in
ifie power ^circuits must not interfere with the lighting oirouits, and to
piwent this, two sets of bus bars are provided. The generators are con-
nected in the usual manner to one set of bus bars, and the lighting circuits
ace oonneoted across these. Across the other set of bus are connected
the drouits supplying the fluctuating load, and the batteiy is also oon-
neoted directly across these power bars. The power bare are supplied
with oorreat from the li^tingl>ars. a non-reversible or so-called " constant
eurrent" booster being mterpoeed between the two, as shown in Fig. 14.
Sinee this permits onb^ a constant current to pass from the lighting bus
bars, the load on the generator does not razy. although the load on the
power busses may vary widely. The oonnectiona and operation ol this
IS follows:
Fio. 14.
Hie booster armature and field are in series between one side of the Iigfat-
ing and power bus bars. A shunt field is also provided, which acts in
opposition to the series field. This booster carries a practically unvarying
current from the lighting to the power bus bars, regardless of the fluctua-
tions of the external load, which current is equal to the average required
by the fluctuating load.
Except under abnormal conditions, the shunt field always predominates,
giving a voltage which is added to that of the lighting bus bars, so that the
voltage across the power busses is always higher than that across the
lighting by an amount equal to the booster voltage.
^ If an excessive load comes on the power circuits, the increased excita-
tion of the series coil, due to a slight increase in current from the lighting
to the power bus bars, lowers the booster voltage and consequently reduces
the voltage across the power bus bare. The battery discharges, furnishing
an amount of current equal to the difference between that required by the
load and the constant current through the booster.
If the power load decreases below the normal value, the slight decrease
in ourrent in the booster series field increases the booster armature voltage,
end the excess current goes into the battery. The booster therefore does
not in reality give a constant current, but by proper design the variation
Btgr be kapt mthin a few per cent.
894
STORAGE BATTERIES.
liMe
r.
Fio. 15.
Fieoie 16 BhowB a diagram representing one form of booster for prodw^
InR (diarae and diBcharae in aooordanoe with variations m load, in wfaioh 0
represents a series field winding, and / a shunt field winding. The gen-
erator output passes through the series winding, and the current in the
coil JS is to remain practically constant. The shunt coil / produoea a field
which opposes the field produced by 8, the resulting magnetisation betng,
in direction and amount, the resultant of the two field strengths.
The adjustments are so made that
when the normal generator current is
passing through the series eoil 5, the
shunt field just neutialiaes its effeet,
and the resultant magnetisation is aero.
Sinoe the open-drcuit voltage of the
batteiy is equal to that of the system,
neither charge nor discharge takee place.
WttJi increased demand on the line, the
slight increase in generator current in
the coil 8 oveipowers the shunt field, and
causesan E.MJF. in the booster armature
in such a direction as to assist discharge.
If the external load falls below the average demand, the current in tarn
coil S decreases slifldithr so that the shunt field predominates, producinc a
booster armature E.M.F. in a direction to assist charge. Althouc^ tne
voltage of the battery falls while discharging by an amount proportional
to the outfiowiog current, the increased excitation dae to this current
through 8 is also proportional to it, and tlM booster voltage rises as that
of the battery falls, their sum being alwi^^ equal to that of the ssrstem.
In other words, the booster serves to compound th^ battery for constant
potential.
» Mxtmrmmilj CoMteoUed m^o^n.
»
The types of boosters before idescribed, depend for their action on the
differential reUtion of shunt and series coils, and prpdace a constant volt-
age change, to charge oc discharge the battery, w^th a given change in
generator ourreni. • This is not the desired relatiobs|iip, as the voltaes
required to. e£fectt o) given char^ or discharge of a oattei7 varies greatly
with its state of charge and its condition. Also, such boosters require
large frames for a given kilowatt capacity in order to aooommodate the
windings.
Recently, systems of external control have been devised, whidi make
use of orcUnary shunt^wound machines as boosters, the fields being regu-
lated to produce the proper voltages for effecting charge or discharge, by
an .eiEtemal device which is. in turn, controlled by small ehanoes in gener-
ator current. So successful ha.v9
these later forms been, that they
have superseded the differentially
wound boosters for both reversiUe
and non-reversible control.
One form is that of Hubbard, in
which the external controller is a
small exciting dynamo. The gen-
eral. arrangement is diagrammati-
callv shown in Fig. 16.
Hie exciter is provided with a
single series coil, through which the
station output or a proportional
part thereof , passes; the armature ol
the exciter is connected to the excit-
ing coil on the booster, and thence
across the mains, as shown. With
the average current passing throui^
the field coil or the exciter, its arma-
ture generates an E.M.F. which is equal to that of the system, and in oppo-
cxcrru Mum eoii.
tTVMt
■ocxrniii
MRIM cote
I
Fio. 16.
B008TBBS.
895
■ition to it. ThMe two oppotinm EM.F,*b bahaoe. tad no oumnt flows in
the boostor field cdb. Witn mn mcrease in extemiu loftd Above theavemoe,
the tendenejr is for an inoreaae to take plaee throui^ the exciter series coil,
ausmenting its field strength and consequently the exciter an&atvre voltage.
This latter now bcinc hif^er than that of the fine, causes eunvnt to flow
in the booster field coil, in sueh a direction as to cause an E^.F. in the
booster aimatnie nHiioh assists the battery to discharge, and is of a magni*
tade to compensate for the battery drop occasioned tberebv. When the
load decreases below the normal, the enrrtnt in the ncdter field is decreased,
and its annature voltaee falls below that of the system. Current will now
flow in an opposite direction in the booster field coil, generatinR an E.M .F.
in the booster armature to assist oharBS. Since the exciter alwajrs (pener-
aies a voHase in opposition to that of uie line, this system is known m the
trade as the Counter E JI.F. System.
Another typeof eocteinatly
eontiolled booster is that of
Elnts. The anangement and
oonneetions are shown in
Rr. 17.
Rt and R9 axe two reeis-
tanoes made up of piles of
csurbon plates. These resis-
tanoes diminish greatly in
value when subjected to pree-
sure. Ir is a lever resting on
the to]^ of the piles, Rt and
fist which is puUed downward Flo . 17.
to comprees them, by the
spring at one end and the electromagnet 8 at the other, as shown.
The magnet winding is in series with the current from the generator, and
with normal output to the load M.M., the pressures of the spring and the
magnet are so related that the resistance of Ri^ euuah that of Rt. The
booster field has one terminal connected to the middle point of the battery,
and the other terminal is connected to a wire which joins the upper ends of
the two carbon piles.
The lower end of Rt is connected to the positive side of the circuit, and
the lower end of R9 to the nefsative side.
The drop throui^ Ai plus /C2, i.e., from the positive to the negative side,
is equal to the potential of the S3^em, and therefore, when Ri is equal to Rt
the drop through either is equal to one-half the potential of the system;
hence the potential of the terminal of the field coil /, connected to the
upi>er ends of the reastances, is midway between the potentials of the
positive and ncugative mains.
Since the other ternunal of coil / is connected to the middle point of
the battery, its potential is also midway between the potentials of the
positive ana negative mains, from which it follows that when Rt and Rt
are equal there Is no difference of potential between the field coil termi-
nals, consequently no excitation, ana the booster potential is sero.
If the external load should increase, a small increase in generator current
win cause a stronger magnet puU, decreasing the reastance of Rt and
increasing that of Rt. The drop through ^t becomes much less than half
the potential across the mains, and ccmsequently there is a potential across
the field winding / to cause current flow from the middle praint of the
battery, throuj^ the winding, throui^ tl]« diminished resistance JZ*. to the
negative main. This i>roduoe0 a booster E.M.F. in a direction to mscharge
the battery and cause it to assist the generator to supply the load demand.
Conversely, if the external load M.&t. should decrease, the diminished
pall of the magnet due to the slight decrease in generator current allows the
spring pull to predominate, and the resistance dt Hi is decreased while that
of R^ LB increased. The field / becomes excited by current flow from the
positive main, through the diminished resistance iRf. through field /, to
the middle point of the battery. This sets up an E.M.F. in the booster
armature to charge the battery, the difference between the normal gen-
erator output and the load demand being thus absorbed.
Owing to the comparatively small change in the pressures which the
magnet 8 exerts, and the thereby limited sixe of the carbon piles, this sys-
tem is only directly applicable to small boosters. Where large machines
896
STORAGE BATTERIES.
are to be controlled, the booster hae a amall exciting dynamo, its field beinc
controlled aa above described.
Another form of externally controlled booster is that of Bijur and is
phown diacramraatically in F^g. 18.
The booster field winding has one terminal connected to the middle
point of the battery, the other terminal being connected to the wire Joui-
mg the resistances Rt and R*. L is a lever carrying at either end a number
of metallic contact points Pt and Pa which dip into troughs of meroory
D] and Z>2 when one end of the lever moves upward or downward. Tliese
points are connected to corresponding points on their respective resiaUuioes.
and therefore all of the resistances connected to contact points which are
immersed in the mercury are short-circuited. The points are of unequal
length, being in a step formation, so that they gradually contact with the
mercury as the lever is moved.
If more of the points Pi than points P3 are immersed in the mercmy the
resistance iZs is less than £1, more sections of it being short^reuited.
Current will therefore flow from the middle point of the oatteiy, throudi
the booster fleld / and throudi resistance R2 to the negative side of tas
system, exciting the booster field and producing a booster EJf.F. to oharfe
the battery; while if more of the points Pi are immersed the resiBtanoe Ri
beoomes the smaller, and current then flows from the posithre aide of the
P +
.1^®®
i:
system throudi resistance Rt, through booster field /, to the middle point of
the battery, the field exdtation and the booster E.M.F. pitxluoed bong in a
direction opposite to the first described, and tending to discharge the battery.
When the resistances Rt and Ra are equal there is no potential to send
current in either direction through the field coil /.
When the load on the external circuit lb normal, the lever L is in a hori-
sontal position, resistance of Rt is equal to the resistance of Rm, no current
flows through the booster field, the booster E2Jf.F. is sero, and no current
passes into or out of the battery.
With increase of external load the pull of msgnet 8 is strengthened by a
small increase in generator current passing through the wmding. "lius
draws down the left end of lever L, overcoming the pull of the spring. The
contacts P| are immersed to a greater or less degree m the mercury, thereby
short-circuiting portions of Rt and decreasing its resistance. This pro-
duces a current now in the booster field to cause an E.M.F. to dischaige
the battery and assist the generator to supply the load demand.
A decrease in ext^msj load is att^ded by a slight diminution in gen-
erator current; magnet 3 is weakened, the pull of the spring predominates,
resulting in a movement of the lever to immerse points P2 in the mercury
trough D3 and thereby reduce the resistance of /fa, causing excitation m
the booster field to produce an E.M.F. to send charge mto the battery.
The essential difference between this form of regulator and other tgrpes
is that the design provides for a condition of neutral equilibrium between
the pull of the magnet and that of the spring for any position of the moving
parts; that is, with a given current jMUsinC throuf^ St the pull of ^he msg-
net * "
INSTALLATIONS.
897
<|D«ntly, thfl ehaace in the generator eurrmt with ohaiige in external load
is apt pro^rtioniQ to the load but is a fixed amount. This variation is
jnat Buracient to cause such a change in the pull of the magnet that the
resulting unbalanced force overcomes the friction of the parts. The lever
will begin to move and will continue to move until the current through 3
i» restored to its normal value, which is accomplished by causing the bat-
tery to absorb or discharge current equal to the difference between the
xK>rmal generator current and that supplied to the external load. The
eihange in the reristances, being made b:^ the immernon of the small eon-
tact points in mercuiy, offers no appreciable opposition to the movement
of the parts and thxis allows a contmuous condiUon of neutral equilibrium
to be maintained throughout the travel of the moving parts.
Obviously by providing externally controlled boosters with a sindte vari-
able resistance, a non-reversible booster is produced, its action beini^ in
effect the same as that described under tne heading " Non-Revennble
Booster."
Reversible boosters should be used where the average, total current to
the fluctuating load is greater than the battery discharge current, and
where the jwtential of the power bus bars must not fall off with increase in
load. Electric railway ana lighting plants having long feeders are examples
of the sjrstems to which reversiDle boosters are suited. Non-reversible
boosters should be used where the average total load is less than the bat-
tery discharge current, and where a drop in the potential of the power bus
bars is of advantage. Examples of such plants are hotel or apartment
houses where electno elevators are operated from the lighting dynamos.
Boosters are usually driven by electric motors directly connected to
them, though any form of driving power may be used. They are scune-
times operated by engines or turbines.
MMtellatloaa.
Figure 10 shows diagram of connections and Fig. 20 the switchboard of
ft battery equipment for a residential lighting plant. In the diacram, the
▼oHmeter and voltmeter connections have been omitted. The bus bars
oo the battery panel are connected directly to the bus bars on the gene-
rator panel. In this installation the generators are ran during the after-
'I'l'I'l'I'I'I'I'I'I'I'l'i'l'I'M
FiQ. 19.
896
STOBAOB BATnatlBS.
i^
/
\
I
DIFFERENTIAL
' AMMETER
11
BATTERy
SWITCM
MOTOR 8TARTINQ BOX
BATTERY
CIRCUIT
BREAKER
4
VOUMEXER
VOLTMETER
8WJTGH
U LJU
!L
CUARQE AND DISCHAROE
SWITCH
I
n
BO08TERFIELD
SWITCH
BOOBTERFIELD
RHEOSTAT
MOTOR SWITCH
t3NDERLOAD
GJRCUrr QREiX£ir
END CELL SWITCH
i
lllgSIE^II
i
FlO.20.
noon, efaargins the battery and supph-ing the load. Whoa the battsfy
if fully charged the generators are ahut dovn and the battery caniet
the load alotfe. In this manner the plant gives oontinuouB Mrvioa, while
thegenerators are run only from five to nine houn per day.
The bui bar voltage remaine oonstant at all tuaee, tha battery Toltaca
INSTALLATIONS.
S99
diMbme beinc raculated by mean* of mi aad odl fwHob. On ehftfie.
the fiJi.F. above thet ol the bui ben, nqwied to brine ell eeUt up to turn
ebar8»,is lupplied by meens of e motor driren ohergUit booster, the volteg*
•t the ennetttie b«ine auitebly veried by ehenging the field exdtetion.
FSsure 21 ■hows diecrem of oonneotioos erranged for eherging the bet*
tery In two pereMsl jpoups end dieduusing in Miies, the oherpe end die*
cherge being eontraued uy Terieble leMsteDoae. In yeoht hgbting the
Kmited ipeoe generally Mohibits the use of a ehevging booster, end in saeh
inetaaoss this method of eherge end cUeehacge oantrolis the usual preotioe.
In cess the generator from whidi the battsry is oharged has suffieient
range in voltage to oharge all esils in series, a eherging booster is not
I A 6 }
VnocauMS
CtMOUU eitAKCII
OVMLOAO ^
OMCUITl
-•••we
FIO.21.
fequiied, nor is it neesssary to eonneet groups of oeDs in parallel, es the
generator vohage may be varied es ohar^ proceeds.
The diecam shown in fig. 22 permits of ehargiDg the battery at one
voltage ana supplying lii^ts at a different voltue. As may be seen, two
end cell switches ere required for this plant. The voltage of the supply
circuit is adjusted by the number of cells in series on switch iSf, while Sz is
moved to cut out cells a» they become fully charged. In tU.^ instance the
end cells included between the contact arms of the two end cell switches
must be of sufficient sise to receive the charging current, plus the current
to the supply circuit.
If the battery can be charged at times when the genemtor is supplying
no other loed. only one end cell switch is required.
. Figure 2a shows a diagiam of connections for a constant eiirrsnt booster
system, in which the same genemtors supply a lighting and a power load*
the bettery being connected directly across the power bus bers. The
diagram further provides for the bettery to supply lights at such times es
the gsnentors may be shut down.
Tlire«*'Wlve Bytitm
In thne»wtro ssfstems it is usual to put in two equipments, one on each
side of the system. Figs. 24 and 25 show the genera] schemes of two
oiiierent
plete bi
In this „
the neutral being taken from the battery. This makes a good errange-
ment. One side of the betterv system will discharge a Bumdent current
ta take up any unbalanced load.
900
ffrOBAOE BATTERIES.
k
ngiire 26 is a battery three-wire syBtein in whieh only end booeter b
vsed. The mein battery iA ^hargDed from the outaides of the syetem, and tbe
booster forms a tooal oirouit m the end oeils and gives them the proper
charge; the voltaoe of the system being high enou^ to ehatye the oella v
the main battery. In the ooosters shown in these diagrams the arm*-
tures only have been indicated, as in nearly every instanoe booeten on
three>wire systems are merely diarging nuushines, the fields beinc separ-
lately exdted from the bos bin or from the battery.
Figures 26 and 27 show eleariy the switchboard conneetions of a central
stati<Mi battery woridng on thiree>wire nmtems. It is obvious that the
systems would work just as satasUetoiily u the 0Bncratot« wafe of a potest-
-;
^'Y^
ii<i<{i
QQQQOQQQQ9%
666666666
tMDCIU.
St
FiCF. 82.
tial equal to that of the outsides, and connected directly
as any unbalancing would be taken up by the batteries.
the
liatterj Capacity.
In computing the capacity of a battery to give a certain discharge, it it
necessary to take into account the fact that the o^iaflitv of a oattery
varies greatly with the rate of discharge. This variation in capasity can
be computed from the curves. Fig. 1. Taking the ei^t-hour rating as a
basis, it is seen that only 60 per cent of the ampere hour oapacity is avail-
able at the one-hour rate of dischanse. Therefore if 200 ampere hours be
required at the one-hour rate, the normal ampere hour capacity must be
•szsr ** ^^ ampcie hours. In a like manner the normal capacity required
for any other rate may be obtained. In the case of a load eorvs such at
BATTICBY CAPACITT.
C^)-'-HIl
22: r
iiiiiiiiiiii
:cjM
m
902
STOBAQB BATTERIES.
I
/
that ihowD in FEc. 7, when the peak dBe if to be oanied by the faAt4crr<
it win be Men that the rate oc battery diMsharge changwi oontinuafly.
If the ana of the p«ak be taken above the line of cenuKataon supplxi
^G. 24.
t t t
J
/Of
■©
MKKIUTM
j ,? t
.■CUT.
•I'HtM+Httmtt
e
Fio. 26.
«*
d§" it will be found equal to 650 ampere hours, and the time of disdiariB
is 2.1 hours. ^ ^ . ^
On a basis of the two-hour discharge rate, the stse of battery raquired
« S^ . 8G0 ampere hours. This, however, is the average rate of dis-
M% . . . «« .^
and on a basts of 860 ampere hours battery oapaoity. When the
BATTERY CAPACITT.
903
diachwga tekee place along the hish portion of the peak at S the amperca
supplied by the battery are 400, which ie nearly the oDe-hour rate. To
determine the actual capacity required to take care of the load indicated,
a capadiy greater than that aeoenary for the ayerasB rate of
•f lUalM
fr
JT&
4- AuUim
'.
-H
CM_A -f Bwlwbw
~ AuUlMy
rn
win
C MA CM AC MA
Tig. 99.
•If (If f I'
fi^ ff^
CM
A-r.
».P.ftT.»t«i«»
A«««ttr
•.PAT.
HD-
^ffTff
3MAa».
tMO-lXMAMp.
C«ll»«iMk;
_ J>iJ«fitol
rj_A«-w_
^llSMb^Asr. Bad (Ml
_■«••• r
A«i 1ft
twtuk
X$mf»
FIO.S7.
cfiacharge. The portion of the load peak to be carried by the battery !■
divided into vertical divisioDs, aa indicated by the dotted linee. The
ampere hours of each strip, divided by the rate of discharge factor (from
ourvea, Fl^ 1), givee the ampere hours capacity, on a basb of the normal
for that particular strip. - ' " ""^^ '"* -
sate, required
The sum of all tfaese capadtiee
004
STORAGE BATTERIES.
miut b6 the eapftdty of the proper battery. If the assumed figure be too
siaall or too lurge, a second computation must be made, based on a capa
city again assumed, which is greater or less than that just taken according
as the result of the first computation is too small or too large For instance,
if peak E be divided vertically into areas V, W, X, Y, and a 900 ampero
hour battery assumed as the proper sise, the nornuu rate of discharge iriB
be 162.5 amperes. The ampere nours of area V are 76, and the avenge
discharge rate is 210 amperes. Dividing 210 by the amperes of normal
discharge, tJlie result is 1.86. Locating 1.86 on the right-hand aeale oi
curve. Fig. 1, and moving horisontally to curve No. 2. and then downwards
to the lower scale, it is seen that this corresponds to the Si-hour rate. The
percentage of the normal capacity at the eight-hour rate, when the dis-
charge takes place at the 8i-hour rate, is shown by curve, Fig. 1, to be 78
per cent. The capacity required to cover strip V then is -^ix ■" 90 ampere
.78
hours. Similariy the ampere hours of strip W are 193, the rate of dis-
340
charge 340 amperes, the factor ■■ TTo~e "" 3*02 corresponding to the 1^-
hour rate. Percentage of eight-hour capacity, .68. and ampere houn ■■
.68 •^•
In a like manner, the capacity required for area X is 269 ampere hours,
and for Y is 237 ampere nours, the sum being 938 ampere hours. The
assumed capacity is therefore nearly correct, and a 960 ampere battery
will be the proper sise in this case.
If the battery is also to be used for supplying the light load from 11 p.m.
to 5 A.M., the capacity must be computed from the area A, k, m, n. which is
990 ampere hours. The rate of discharge is fairty constant, and extends
over six hours. The percentage of normal oapaoity available at the six-
hour rate of discharge is 94 per cent.
990
-^ *- 1060 •» ampere hour capacity of battery required to carry the
load given from 11 p.m. to 6 a.m.
•traartk of IMlMto ABlpbvHc Add •f IfttftoMBi
(Otto,)
Per Gent
Specific
Per Cent
Percent
Specific
Per Cent
of H^O«.
Gravity.
of SOi.
of HaS04.
Gravity.
of 80a.
100
1.842
81.63
23
1.167
18.77
40
1.306
32.65
22
1.169
17.96
81
1.231
25.30
21
1.151
17.40
80
1.223
24.49
20
1.144
16.32
29
1.216
23.67
19
1.136
16.61
28
1.206
22.86
18
1.129
14.69
27
1.198
22.03
17
1.121
13.87
26
1.190
21.22
16
1.116
13.06
26
1.182
20.40
16
1.106
12.24
24
1.174
19.58
14
1.098
11.42
Ordinarily in Aoeumulators the densities of the Dilute Add vary between
1.160 and 1.23a
^
CONDUCTING POWER OP ACID.
905
wer •# ]Ml««e AmlplHuric
iMattkieMsen,)
Sulphuric
Relative
Spedfio
Acid in
Temperature.
Reaiitancee.
Gravity.
lOOparts
by Weight.
C*
OhmajDer
cubic centimeters.
1.003
0.5
16.1
16.01
1.018
2.2
15.2
5.47
1.053
7.9
13.7
1.884
1.060
12.0
12.8
1.368
1.147
20.8
13.6
.960
1.190
26.4
13.0
.871
1.215
29.6
12.3
.830
1.225
30.9
13.6
.862
1.252
34.3
13.5
.874
1.277
37.3
• ■ •
.930
1.84S
45.4
17.9
.973
1.393
50.5
14.5
1.086
1.402
60.6
13.8
1.540
l.«3S
73.7
14.3
2.786
1.726
81.2
16.3
4.337
1.827
92.7
14.3
5.320
1.838
100.0
■ • •
• . .
CoMdvcttef Power of Acid mmA Aallme ftol««i<
Copper (Metallic) at 66*' F 100.000,000.
Sulphuric Acid 1 Measure )
Water 11 Measures ( qo n ..>n».^-».««
(Equal to 14.32 parts by weight of Add in 100 ( ^'^ approximate.
parts of the mixture), at 66^ F )
Sulphate of Copper, saturated solution at 66° F. 6.1
Chloride of So<£um, saturated solution at 66° F. 35.0
Sulphate of Zinc, saturated solution at 66° F. . 6.4
i<^
SWITCHBOARDS.
BsnsxD BT H. W. Youiro, B. P. Bows axd E. H. Hjwltt.
Thb object of a switchboard is to collect the electrical enei^^ in an inataH^
tion, for the purposes of control, measurement and distribution.
In small stations this is accomplished by concentrating the energy at a
sin^e place. In the largo modem stations this is often impractical, and it
is, therefore, customary to concentrate only the control and measurins
apparatus.
There are two general tsrpes of switchboards:
s^ \ (1) ]Mrec«-GoM*rolPMiel0wlteld»MiriU, in which the airitolimc
** and measuring apparatus is mounted directly on the switchboards.
(2) Reaioto-CoMtrol •wlte]dH»«Mu. in which the main current
oarrying parts are at some distance from the controlling and measuiing
apparatus. Tlus type may again be divided into two divisions, vis.: han^
operated remote-control, and power-operated remote-control apparatus. The
best modem power-operated apparatus is electrically operated, although
there are a few installations which have employed compressed air.
The above general types may both be sub-divided into Direet-Curreat
and Alternating-Current Switchboards, and there are numerous and distinct
classes in eadb subdivision.
It is customary to mount apparatus and switching devices for low-tension
service up to and including 750 volts directly on the face of the switchboard
panels.
For voltages from 1100 to 6600 volts it is necessary to eliminate all Hv«
conductors nx>m the face of the switchboard to insure safety to the operator.
If the plant is of small capacity, the switching devices and conductors may
be provided for on the rear of the panels. Heavy capacity plants from 2200
to 6600 volts, however, are invariably remote control, and nearly always
electrically operated.
In all high-tension plants from 6600 to 33,000 volts the switchboard is in-
variably remote control, and if oS heavy capacity it is invariably eleetoically
operated. In large stations, for pressures above 33,000 volts, switohboar^
are invariably Mectrically operated remote control. In small capacity
installations where the high-pressure swvice consists of only one or two
incoming lines, which will not warrant expensive remote control switches,
a set df simple fused circuit breakers or expulsion fuses are often installed
and a switchboard dispensed with. Cut out switches are used, however,
in addition, for disconnecting the lines.
IBeaIni of IMroct-CoMtroI Panel Bwttthbomwdm, — In de-
signing buildings for control stations or isolated plants, the switchboard
shoula be located in an accessible place, with plenty of room in front and
rear. If care is taken in locating the various paneb with respect to the
machines and feeders to be controlled, much unnecessary expense and com^
plication may be avoided.
If extensions to switchboards are expected, which is usually the oaae,
pands controlling generators should be together at one end of the switdi-
board, and those controlling feeders at the other end. When total output
panels are used, they are placed between the generator and feeder sections.
It is advisable, however, m some special oases, in order to save copper in
the busses and simplify the station wiring, to interminsie the generator and
feeder switches although even in this case it is desirable to group the gen-
erator indicating devices together and likewise those of the feeders.
Unnecessary complications and extra flexibility being at the expense cf
simplicity are always to be avoided. For instance, in a majority of cases
it would seem unnecessary to provide more than one set of bus bars.
Plainness, neatness, and svmmetrv in design should be aimed at, and
Bothini^ placed on the switchboard which has no other function than orna-
mentation.
Sufficient indicating and recording instruments should be used to deter*
906
L
8WITCHBOABD8. 907
•
mine if the niMhinea Are working efficiently, to obtain a noord of the outi^ut
of the feedera, to detect eztenutl or internal trouUeB, and to ohedc with
records obtained from outside sourees. The degree of accuracy required in
the s^tohboard instruments depends entirely upon the conditions involved,
greater accuracy being required where power ui bought or sold. Instru-
ments ^diich are accurate to within 2 per cent of the f uD scale deflection will
generally fulfill all requirements.
Switchboards are now standardised, covering a large range of requirements,
and standard panels are advisable for general use, although epecial conditions
nuMT usually be met with small modifications of the standaras.
For ordinary direct-current switchboards, 4 feet is little enough behind
the panels. In any case there should be a clear sraoe between the connec-
tions on the paneb and the wall of 2i to 3 feet. For heavy direo^-eurrent
work and moet alternating-current work tt is often neceesary to have 6 to
8 feet behind the panels.
Hand-eontrol panel switchboards may not be advisable in direot-cunnnt
stations where cspaeities are laiige, and in such cases remote-control instnuQa-
tions should be considered. It is ukewise inadvisable to deeign switchboards
of this class for heavy capacity alternating-current circuits of 2200 volts or
upward, as the conductors for such service should be specially isolated. '
It should be noted especially that heavy capacity conductors and switch-
ing devices for oisouits of 4000 alternations and above abould be avoided,
on account of excessive heating to be met with due to eddy currents in the
conductors. It is doubtful if satisfactory switching devices can be easily
procured, which will carry currents of more than 3000 amperes at 7«M0
alternations or the equivalent, and such devices require special design and
expense.
in locating swit<diing apparatus it is usually assumed that dynamo leads
come up from bdow, and feeder wires go out overhead except that under-
ground feeden naturally go out below.
In order to avoid a very unsightly complication of wiring and apparatus
on the rear of switchboaixis, it is best to locate series and voltage trans-
formers apart from the switchboard on the incoming and outgoing cables,
if at all sossible, and to make all large rheostats operate with sprocket ana
chain, thufl kicating the rheostats scnpuurate also. Any extensive system of
fuses to be suppUcid on the rear shoufd preferably be provided for on a sepa-
rate framework.
The material from ^hich panels should be made varies with the service.
Plain slate can be used for anjr panels where the potentials are not above
750 volts. This slate may be either plain, or oil filled, or it may be given a
blaek finish. The black enamelled slate is very satisfactory for use where
oil is prevalent, but it shows scratches easily, and is not easily repaired if
shipped-. The most popular finish is the black marine, which may oe made
dQ Jbroof, and is a durable dead black. It is easily replaced when damaged.
For switch bases and panels not xeauiring finish, soapstone is often used
as it is a better insulator than slate, the latter being liable to contain con-
ducting veins. Such slate should be rejected.
Marble is largely used for switchboard panels because of its good insulating
Jiualities. Many varieties, are available, the most ooxnmoa being the white
talian, pink or grey Teniiessee, and several varieties of blue Vermont
marble. The colored nu^tblei do not show oil stMns as readily as the ^ite
varieties, and present a more pleasing appeamnce. The blue Vermont
marbles are more uniform in coloring, and therefore easier to match; but if
absolute uniformity in this respect is desirable, it is advisable that all paneb
be given a black marine finish, as it is often difficult to get new panels with
exactly the same shades and markings as those it is desired to match, marble
being a natural product.
Stapdard Central Station switchboard, panels are commonly made 90
IncheB high, and composed of tWQ or three slabs. The upper slab of a two-
^eee pan^ is usually from 60 to 65 inches high, the lower one being from
25 to 30 inches high. The General Electric Company's standard is 62 and
28 inches respectivelsivthe corresponding Westinghouse Standard being 65
and 26 inches. The Westinghouse three-piece panel has an upper slab 20
inohes.high, middle slab 45 inches high and lower slab 25 inches, the 20-inch
■lab being provided primarily to permit circuit breakers to be directly
mounted thereon, and allow of easy removal in case of substitution or
repairs.
(
SWrrOHBOABDS.
■iana cIvMi Mu
SwitahbcHrd fnunesfor
ik for inUted pbwU. the Watln^uniH itudud for
48 lnofaM biih BDd 11 or 1) iouha Ihiek u raquired.
-- ■- — --[1710 i Inch aU uouod the (rant ■>£[«■ tlie
" ' Itom ths «d«ea ol the puiel, BDd not Be
eKvy puieJfl
cf OButnJ Si
Slatloa Buritahbaard fnuna u
mada ol atael BOile ban TBryinK from 21 X 1 1 X ) Inehaa to 3 X 2 X 1 iuta.
The Bosle ban are gupportM (n an upritht palnlioo on a level itriit «Ua
neU on ih* floor. Tlila may be of elate, an invertad cbannel Itod. or a hud
lie pani^ are bolted to the nanov veb at the ande ban and tha adlaaant
anile* ballad tonther Uirou^ their vide wsba. (&» ¥]». Z.)
Another method mod mtb paneli whiob sairy a moderata veicht d
■pparatiu ka to maka a frame oI iron [Hpinc aBBured lo tha pwmIb by omim
a Buitable iron lupportinc dampa.
SVITOBBOABDS.
909
TIm f nuDflWork of all svitehboArds ahould be fawiUtad f lom sround whmi
used on t^temfl ci 600 volta or less. In hi«h-t«nBion altem*tinc-4Mirrani
■vBtems, It ifl neoessaxy to ground all framework to carry off ratio dia-
obargea, and to inaure safety to the operator, should he touch the frame-
work. For seouiinc the frame in a vertical position, rods are used with or
without tumbuckleB, or dse angle iron braces.
Ae a general thin^ alternating and direct-current panels should never be
intermini^ed. espeouuly when this involves the mingling of conductors on
the rear.
It is recommended that illuminating lamne be omitted from the front of
■witehboards. and that the instruments be Illuminated by lamps in front of
the same.
The copper bars and oonneetions on the rear of switshboards should be
**/^e^»>
Showing Method
dngS^tohboard
Fknel to WalL
Fro. 4
of Bradn,
Fro. 5.
Showing Gaspipe
Frame woik.
earcfully laid out in order that the current may be carried economically and
without ovwheating, and especiaUy to prevent undue crowding and msure
a neat and workmanlike appearance. The best ])ractice requires that bus
bars be not placed near the floor. Switches, circuit breakers and other
i^paratus are connected up with bare copper strap or insulated wire as
oeession requires, bent in suitable forms. Where bus bars are not rigidly
■upported| it vb not recommended, as a rule, to have long studs on the appa-
ratus, projecting out far enough to connect to the busses, as the strain on
the apparatus due to the weight of the busses may affect the adjustment
of electrical contacts. Except for small switchboards the bus ban are
usually supplied with insulated supports.
Bare flat or round copper bars are now used almost universally for con-
ductors on low-potential switchboards, the flat bar being usually preferred
on account of ease in making connections and the facility with which addi-
tional capacity may be provided for. The prevailing thiekneBsee vary from
i to I inches with widths proportioned to suit the capacity. The sise of
oopper conductor is usually figured out on the basis of 800 to 1000 amperm
per square Ineh of eroas section . By property laminating the bars, even very
dio
SWITGBBOARDS.
heavy euirents may be provided for on this basis. Contact stufaoes should
be fignred on a basis of 100 to 200 amperes per sauare inch aooording to the
method of damping, bolting, or soldenng. Bted oolts are used in clamping.
Oire must be taken, however, with altematinr-eurrent circuits to see that
iron damping plates and bolts do not form complete magnetic dreuits and
cause undue neating, due to eddy currents set up in the iron.
Oonnections and apparatus for carrying current should be guaranteed to
oury thdr normal current at a temperature rise not exceeding 25* C, above
the surroimding air. Rolled copper should be used for conductors to secure
the best conductivity, but it is often necessary to use copper or brass eastingi.
As their conductivity is usually low, such materials should be avoided as
much as possible. Where it is necessary to use castings they should be of
new metal only and care should be taken to insist on a standard of condne*
tivity for each piece where such a condition counts. The ordinary mixtures
vary from 12 to 18 per cent according to mixture. A conductivity of 50 per
cent may be considered high and suffident, but it is not obtainable in a
regular brass casting.
The following table from "Modem Switchboards.*' by A. B. Herridc, gives
percentages of mixtures with resulting conductivity as compared widi 100
per cent copper:
%
%
Conduc-
%
nJ^
Conduo-
Copper.
Zinc.
tivity.
Copper.
•Hn.
Uvity.
98.44
1.56
46.88
98.59
1.41
62.46
94.49
5.51
3a. 32
93.98
6.02
19.68
88.89
11.11
25.50
90.30
9.70
12.19
86.67
13.33
30.90
29.20
89.70
10.30
10.21
82.54
17.60
88.39
11.61
12.10
75.00
25.00
22.08
87.65
12.35
10.15
73.30
36.70
22.27
85.09
14.91
8.82
67.74
32.26
25.40
16.40
83.60
12.76
100.00
27.39
100.00
11.45
All minor connections to bus bars such as switcb leads, feeder terminals,
or any attachments whatsoever, whether clamped, bolted or soldered, should
have ample contact surface contact rated at 100 amperes per sauare inch,
and all round conductors should be cup-soldered to flat lugs leaving proper
amounts of contact surface.
Cup-soldered oonnections should enter the sockets from two to three
diameters. All permanent joints of this nature should be soldered, as
required by the National Board of Fire Underwriters. Where it is essential
to leave a joint that may be easily disconnected, the old style sleeve or
socket with binding screws can be used, but the oonnections should enter
from four to ten diameters to make a secure connection.
An exceedingly clever device to take the place of the connection lefeiteJ
Co or to use in place of cup-soldering is the Dossert joint which is ouickly
and easily applied to the end of a wire or cable, and is so designed as to
insure the full conductivity of the conductor to which it is applied.
The tables given below furnish the dectrical constants of copper and
dluminum bar» which are most likely to be of use to the switchboard designer.
The current which any given section may carry is calculated upon the basis
of a load factor of 50 per cent, and the densities given are those which for
average conditions of radiation would result in a temperature rise of about
10 decrees Centigrade. Where the load factor is to be 100 per cent, and it
is desired to keep the heating within the above limits, the current densities
must be halved.
The data given show in an interesting manner the relative values of copper
and aluminum in switchboard construction.
COPPIB BAB DATA.
Thi CuUtr CoinpaiqF.
Tlu CaUa- Company
91?
BWITGHB0AKD8.
Gbouit breaken, if required to open oirooite earryins heavy loads, ohoold
be mounted at the top of the panels to give the arc plenty of room to net
without eoorehing the inetniments or the panel, ana to keep it above tfai
attendant's head. Instruments should be mounted below the circuit break-
ers, while the lower portion of the panel should be utilised for switdaii^
devices.
Switches, circuit breakers and fuses are usually rated at their maximum
oontiauous ampere capacity and for this reason care should be taken in
selecting these devices. Take into account the one hour, two hour and
three hour overload guarantee on the machines. Indicating instrunkents
should have scales calibrated to read in excess of the overload guarantee of
the machines to which thesr are to be connected. It is usually good practioe
to have the needle about in the middle of the scale at normal loaa, but a
good reading should be obtained as low as one quarter load. Meters a£Fected
by stray fields should be kept away from the inBuence of connections canyii!^
heavy currents.
Pand swiudiboards for small capacity stations for altemating-eurrent
circuits from 1100 to 6000 volts are usually supplied with oU switclies,
mounted on the back of the panels, with handles for manual operation oa
the front. In large stations, however, these are usually replaced by remote-
control switches.
ImauUMtloM ]MateMC«a« — In high voltage switchboard work wbare
there are bare conductors, safe distances must be maintained between the
conductors and from the conductors to the switchboard stmctora. The
striking distance through air may be somewhat less than the distance over
surfaces. The air distance should not be less than two and one half times
the striking distance of the given voltage as taken from the curve on pase
482, and the surface distance should not be less than three times the lur
distance allowed for the given voltage. It is obvious that the greater the
distance the greater the factor of safety ; and In large cuacity stations this
greater factor of safety is usually advisable on Mconntoi the greater Insor-
ance given by the use of greater distances.
The creepage distance to be maintained in the switohboard depends upon
many conditions some of which are: The material of the surface: the con*
tour of the sutface: the liability to coDeot dest and the properties of the dosi;
and the amount of moisture in the atmosphere.
▲]:.niiiiATnrch-cijnRa]fT swivc
The instruments, switches, etc., required for the various tjrpes of paneb
are listed below, for assistance to the engineer when designing a switch-
board. Each type of panel will be described individually.
■qvlpMent ef S-PIUMe Oeaertttor Pamela*
8 Ammeters (one is sufficient for practically balanced loads or may
be connected by means of plu^i so as to read the euitent la
either of the 3 phases).'
1 Voltmeter.
1 Polvphase indicating wattmeter.
1 Field ammeter.
1 Polyphase integrating wattmeter (optional).
1 Wattless component indicator or powcMaetor indicator (optional).
Hie first instrument indicates the useless watts and the iheoetat
should be adjusted to reduce them to a minimum. The power-
factor indicator is used for the same purpose, but does not give a
direct indication of the idle currents at all loads.
1 Voltmeter switch for reading voltage on either of the 3 phases
(on balanced systems this is usually omitted ana voltmeter per-
* manently connected to one phase). . .
1 Ssmchronising switch (one ssmchronism indicator can be used for
all generators).
1 Field rheostat with chain operating mechanism (small machines
may have the rheostat mounted at the back of the panel). If
electrically operated rheostats are used the handwheel would be
replaced by a controlling switch.
ALTERNATINGh-CUSBBKT SWITCHBOABD PANBLS. 9t8
1 Fidd switch with disoharfln clips.
1 Diaehatse raeiatance for field cireuit.
1 Non-automatio main switch (oontroUins switch required if oil switch
electrically operated is used).
2 Current transfonnere (8 trannonners are necessary if neutral of
cenerator is grounded).
Pbtential tnuisfonners (3 potential transformers are desirable If
neutral of generator is grounded, but one is reciuired if used only
for synchronising). Both may be omitted on cirouita of 600 volts
and less, if ail meters have their coils wound for operating at
generator voltage.
1 Engine governor control switch if goveraor is electricaDy controlled.
If each alternator has its own exciter the exciter ramy also be controlled
from the alternator panel, by the addition of an ezater field rheostat.
VOLTHEm
lOAMMimi
ATMARDWMIIL
neiO OMCMAMI SWTCM
VOLTMCTM PUie RICIFTAeLI
FMb 6. 440- and OOO-VoIt Three-phase Qenerator Panel.
Two-phase generator i>anels have a similar equipment to the three-ohase
except that but two main ammeters, two current tranaformen ana two
potential transformers are required.
SiriTCH BOARDS.
AliTSBKATlMO-CUKlUINT flWITGUBOXKO PANU.8. 91$
TM. S. Tm-PhM* Z300-Valt Qcoentor FaoaL
jbeiKtirrjirAnar
2300-Vall Qanntor Pk
916
aWIT0HBOABD8«
•1.
1 Main ftmmeter.
1 OompeDsatinc voltmeter (optional). As nnsle-phaae
invariably used for lighting it is necessary to maintain a
potential at the point of distribution, and as each feeder
is likely to have a di£Ferent load characteristic, potential
tors are frequently installed. The o(nnpaisating voltmeter
pensates for the ohmic drop or for both the ohmic and inductiw
drop in the line at all conditions of load and gives a direct iadi-'
cation of the voltage at the center of distribution.
1 Potential regulator and operating mechanism (optional).
1 Biain switch with automatic overload trip or automatie oirouit
breaker.
1 Current transformer.
1 Potential transformer if voltmeter is used.
1 Time limit overioad relay (optional).
1 Single-phase integrating wattmeter (optional).
r
A«««M>M9C«y
Fio. 10. 2500- Volt Single-Fhase Feeder Paaeb with Primacy Ammeters
and with Series Trip Oil Switches.
ALTBBKATIKG-CUBBBNT 8WITCHBOABD PAXBLS. 917
BlqwiyiWit of VU
3 IfaiD ammeters for tranamissioD lines used to detect any unbalanoinif
due to leakage to ground. A single ammeter may be used if
desired, with suitable plugs, to indicate the current in either of tha
three phases. (One ammeter is sufficient on feeders for induction
motozB and rotary converters, or on incoming lines in a substation .)
1 Polsrphase indicating wattmeter (optional). For power circuits in
mills and mines. This wattmeter gives a sufficient indication of
the output without the ammeters.
1 Polyphase integrating wattmeter (optional).
1 Oil break switch with overload trip, or automatic circuit breaker.
2 Current transformers (three transformers are necessary if neutral of
three-phase system is grounded).
2 Potential transformers for wattmeters.
1 Time limit overload relay (optional). The number of potential
transformen can be reduced for a switchboard containing a niui-
ber cl feeder panels by coaneeting two potential transformers to
the busses and feeding all the wattmeters.
1
I
I
L
flli!
*--«'—»
if
mm
Otenvi^wortbn^
Fig. 11. 26(X>-Volt Three-Phase Feeder Panels with Primary Ammeters
and Stties Trip Oil Switches.
8WITCHBOABI»8.
2 Hkin unraalcrB.
2 Pauathi t:
overtoh] niMy (Dptiotta
Lmlw o[ feeder pAnAlo by eounefrl
to tb* buB« >I
« all the mttowtan.
nifl Diimba of potcntiil
1 Oit break iwitch with OTerinul trip, or
3 Cumnt tTAngfarTDerv.
1 Time limit ovsriosd relay (optional).
ducfli variatian
V npaoity. baoaiue it pn>-
]l at tbem.
3. Bj XuflRHaff «l IaMTB«I ■dalata
3. Bj iBtrsJadiv as Xit«rml Be*
Duil tbtnuch oalleeter Hngi. Tbia rvistanoe is eu
It br« emtroDcr-
.. Mj Tint OsKBeetlBr *k« Xmtmw «■ K.*w-V*lMt« Tapa,
— If the motor ti fad from atep-down transfonnen. it may Snt b« Bon-
necled to low-voltacc taps on the tnuuformar uid then to the full-voltac*
G. By EiMploylir m BttiwUmg CMgetiaaf r. — Many eompeoaa-
lon bava aa iaMrnal switoh for itartinc; othenriM the panel should be pro-
Tided with iwitchas to oooiieet and disoonneot ths oc
u
ALTERNATIKG-CUBRBKT SWITCHBOARD PANELS. 919
■tpBteat of Thvee-Phase Bjm^hr^mmwm Motor P»ools«
1 Ammeter.
1 Three-phase indicatinc wattmeter.
1 Field meofltat with operating mechanism.
1 Synchronising switch. (The synchronism indicator will answer for
any number of motors or the generator synchronism indicator
may be used.)
1 Main oil switch with automatic overload trip.
1 Field switch with discharge resistance.
2 Current transformers.
2 Potential transformers.
1 Time limit overload relay (optional).
A synchronous motor driving a direct-current generator can usuall^r be
started from the direct-current side, in which case the synchronising switch
is necessary. If always started as an induotkm motor the synchronising
switch is unnecessary.
The equipment of a two-phase motor oanel is the sune as for a three-
phase^ except that two ammeters should oe used.
SqvtpniOBt of a Throo-Pliaeo Motmrj- CooTovtor Ponol.
For rotary converters oonnected in the high-tension side of step-down
transformers, the panel for the alternating-current side is the same for three-
phase or six-phase machines.
. 1 Three-phase integrating wattmeter (optional). «
1 Ammeter.
1 Power factor meter.
1 Main oil circuit breaker with automatic overload trip.
1 Ssmchronising switch (not necessary if rotary is started, from the
alternating-current side).
I Starting motor switch (only used where rotary is started by a starting
motor).
1 Switch for synchronising resistance (only used vrhBre rotary is
started by a starting motor). . .
2 Current transformers.
1 Potential transformer (if rotary is started from the directHmrrent
side or by a starting motor).
1 Time limit overload rday (optional).
The above list includes two current transformers which provides against
a short circuit in any phase under usual condittons of operation. Il the
meters are not adaoted to operate on the altemating-ourrent circuit without
series and potential transformers, all of the transformers mentioned wfU be
required for operating the meters. Certain forms of relays may also demand
additional transformers to avoid interference with the accuracy of the meters.
One method of startini^ a rotary converter is bv connecting tht altertiatiog-
eurrent side first to fractional voltage taps on the tranafoimem, and tb^n to
full-voltage connections. This is accomplished by means of double-throw
switches on a separate pand, as shown in the diagram, Fig. 13. Another
method is by the use of a motor on the rotary shaft, as shown on diagram,
Fli. 14.
The rotary may also be started from the direot^current side.' In either
of the latter cases it is necessary to synchronise.
In case several rotary converters must opwate from the same bank of
transformers, it is best to have a separate set of secondaries for each rotary.
But in case of rotaries which must be paralleled on the alternating-current
side under such a condition, it is essential that reactances be provided in
the circuits to prevent interchange of current between machines, and that
switches be provided in the altemating-eurrent leads. These are used as
main switches in synchronising and are usuallv mounted on the alternating
eurreot panel. For the condition just described, the panel would contam
the same list of apparatus mentioned above, except that these switches
SWITCHBOARDS.
)
)
r* Jf»no^n7iar
Fid. 18. Diatnni of Conncctiani, Thn»-PhaM Rotary
itwtod dmotly fiwn Altenutini-CucTtDt 91d«.
ALTEBNATUia-OUBBlMT flWIIOBBOABD PAMBLS. 921
i
with SUrtma Hutor.
RiUn' tram (Im di[«ot4urnot nda. and k Geld tnorfer BwiUh provided for
BH in mtMTiinm- Tbe pud far the jUtemAdnaMnirTODt sida would be tlM
■m* ■■ prvvtously d«nnbad. nanpt lor the derwag nMatioiwd. uid Ihst
gi> ponnr-Iutor met«r i* uimlly rtplnoed by ui LDduBliuc ir-" — ■--
rmrWoa miBt alec ' '- ' ' ' - ' ^ '-
■t aod fouc-irato altviiiaUncHiuinat
r
922
SWITCHBOABOS.
mmt •/
at
ler
for
The primaries cl theM tramformen may be oontroUed by an ofl switdi,
with automatic overload trip, or by plug switches and fuses.
The seoondaries, being of small capacity, are usually oontit>Ued by
plu^ switches. An ammeter should be connected in the secondary side to
Indicate the current and to detect grounds or open circuits.
An integrating wattmeter on toe primary side is a valuable adjimot to
record the total power consumed. The diagram shown is that of a ain^e-
drcuit transformer. Various modifications result from using multi-circuit
transformers and introducing transfer systems in either the primary or
secondary side.
'44tMM^Arrmaif^
■^E"
*Am fliW
\
Fxo. 15. Constant-Current Transformer Panel for Sinfl^e Circuit.
▲mc «¥nT€HiiOAii]»ft.
This line of switchboards represents an entirely different construction
from that of ordinary switchboards.
Extra flexibility makes it desirable, and smaU currents make it poasible,
to use plug connections instead <A the ordinary tsrpe of switches.
The function of arc switchboards is to enable the transfer ol one or mors
arc light circuits to and from^ any of a number of generators. This trans-
ferring is sometimes accomplished by means of a pair of plugs connected
with insulated flexible cable: sometimes by plugs without cables. idUch
bridge two contacts back of the board, or by a combination of cable plugs
and plugs without cables. The type using plugs without cables is preferable
because danger is eliminated, which would otherwise be possible to attendant,
due to contact with exposed or abraded cables carrying hi^-potentiai
current.
The accompanying illustration shows an arc switchboard of the Genefal
Electric panel t^rpe, arranged for three machines and three eiromts. llie
vertical rows of sockets are lettered and the horisontal numbowl. The
ends of the vertical bars are connected to the machines and circuits. Each
of the bars is broken in three places, and the machine may be oonaeeted
to its circuit by plugging across these breaks, thus making the bar eoiH
tinuous: by removing any pair of plugs the machine may be diaconneetted.
Cll, Ell and Gil are ammeter jacks, and are used in connection wilJi
two plugs connected with a twin cable, for placing an ammeter in the eirouit.
The six horisontal bars are for the purpose of traasferrinc a madiine or a
feeder to some circuit other than its own. Each horisontal bar is provided,
at one side of the panel, with a soeket (A8, A4, A5, A7, Aft, and A9) by
means of which it can be connected with the horiBontal bar on the adjoining
panel. All ordinary combinations can be made by means of the bans and
J
ABO SWITCHBOARDS.
plua: but (iabl« plu(i u« provjdad with each paacl, K> Ibftt when mcMMfy,
naioUmal Aofl f«ad«n oan bs tmalami -wiftaul Iha un o( tha b«. Vuto
nliua uid nbin ■» ioieoded tor UM only in esM ol ui emsTKenoy,
^ run nuMhine No. 1 on Itadtt No. 1, ionn plugn inBlD, CK). Be. OS,
<
plu^mtOO mod DS; thu ]atvm P.
^'— -"—- =• — -hilt* No. 2 by iqnerting the plug at E7. Cut out nu<
« tb« plug St DIO •wTBIO. laka out pluc at D7.
r
924
SWITCHBOARDS.
»CI7
Birr A^rxTOMiiOAitii
I
■qvlpaiCMt of D.G. CF«B«i»C«r
1 Overioad eirouit braakor.
1 Ammeter.
1 Voltmeter switch. (One voltmeter will answer for all generaton.)
1 Fidd switch with disoharge resistanoe (optional).
1 Positive main switeh.
1 Negative main switch. (For railway service where tha geBerator
series coils are on the negative nde. and the ncpatiTe aide is
grounded, this switch should be reputoed by a eueuit breaker
mounted near the aenerator, and connected in the armature lead.)
1 Equaliser switch. (Mounted near the genemtor. For small eapadty
generators all three switches may be combined into a tiipie-pok
switch mounted on the panel.)
1 Field rheostat.
1 Reoordin^ wattmeter (optionaT).
For small machines, fuses may be substituted for the eirouit breaken.
■q«i|HBi«at of A.C. aaA ]>.G. Motmvx CosTeitor
The equipment of a direct-current converter panel may be the
a diredt^^uzrent generator panel, but a field switeh with discharge
is unnecessary aad the
mrrcK
e-MWEII FACTOR MCTEII
SYNCHSONtZBR LAMP
SVNCHKONIZefl PLUO RCCCrTACLE
MMCTER PLUO RCCCPTACtU
RHEOSTAT (If NOT MOUNTED,
*~ &a FANSL)
tWrrCH FOR SYN0NR0NI2INO,
RESISTANOI
SWrrOH FOR STARTMa MOTOa
ouit breaker in the n«
tive on grounded return
system should be omitted
as the neoessaxv protectioa
is secured on the altemat-
in^current side. The main
switches, however, shouU
all be sin^e pole.
Rotary eonvertars
started from the altemat-
ing-current side may boiki
up with reversed pMarity,
which will be indicated on
the voltmeter. To t^t^ngm
the polarity back to nor-
mal, a doable throw field
switch is provided (uattsUy
mounted on the ocmvcrtcr
frame) for the puipoee of
momentarily revemnK the
field to **flDp a pole.*^ To
reduce the destmctiTV In-
duelive discharge of the
field a multi-pole switch is
used, each pole of awiteh
breaking only two or three
field spools.
Rotary oonvei tera oper*
ating on grounded return
systems may have the neg-
ative side eonneeted direot-
ly to ground without the
interposition of a switch.
Rotary converters start-
ing from the direotrcttrreat
side require a field-transfer
switch, as well as a starling
Flo. 17. Three Phase Alternating Current switch, which are usually
Rotary (inverter Panel for use with provided with the direet-
Rotary and Starting Motor. eurrcnt panel. A double-
reading ammeter is usually
provided, or else other provision to prevent damage to toe meter by reversal
of current.
DIREGT-CUBSSNT §WITCHBOAKD PANBU.
It or SotuT Stutod br
SWITCHBOARDS.
Pio. 20. OnaiiMtkitiB of s IHraot-Cumnt RotAry OiHiTarter FUmL
Tha Wcatin^unua thrM-win geDBntor enmbicn in ile ayntttn el oon-
neolioiK tii of lb* circBitfl wfaioh were required for tbe uiukI cenvntioc eett
of an Edina three-wire syitem. uid ■ double equipmtBt of appuvtiM ia
required, u loUows:
2 AmmeterB (opaiBtini from Bhtmti laoatod in UTOktun hula if
2 Qrcuit breakos, eudi dtber two pole or «ip[di«d witb nualiar
awCaoM. to open » msla mad equaliied lend (with opaaliuc oou
in the main l«d)'-to trip tocetbiv.
3 Double-pole maiD jswit^^hes.
1 Double-pole two-way vpltmeler ping mnplaisto. ,
1 Field rbeoatat.
2 DouUe-pde balanoiDg eoil awilchea.
(It the unbil)u>eed toad ii to be meaeurvd, a doDble-TeaiUnc dIr««t«uffM(
The oonDeatioDS for such a ayitem are gbowii In diapmm. Flc. 21.
DIRSCT-CUBUDTT BWITCHBOABD PAMKL8. 927
I!!
i
928 8WIT0HBOABDS.
■qal^BieBt ^f D.O. Feeder PttaeL
Direet-ourrent feeder oirouite should be protected from ov«ri<Mu]a by
euit breakers or fuses. Circuit breakws sbould be used if overloads
frequently, such as on railway and most power dreuits. They^oold abo
be used for all large ampere capacity circuits — say above 000 i
Small feeder circuits may be controlled solely by a double-pole cireuit
but on large circuits a switch in series wiui a circuit Ineaker is nc
The equipment diould then consist of:
1 Single-pole circuit breakec.
2 Single-pole switches. (On nounded return systems the
•witdi will be unneoessaryQ
Ammeters and integrating wattmeters are optional devi<
SaaipaeeMt of D.C. Meter
1 DouUe-pole automatic circuit breaker.
1 Starting switch and resistanoe,
or
1 Single-pole automatic circuit breaker.
2 Sin^e-pole switches or one double-pole switdi.
1 Starting switch and resistance.
or
1 Double-pole switch.
2 Inclosed fuses.
1 Starting switch and resistance.
^ Ammetem are optional, but are recommended for motors of lai^e irfmi
r* Either the cireuit breaker or the starting switch should have a low-voltace
rdease attachment. The starting switch and resistance should be so con-
nected that the field, when the switch or cireuit breaJcer is opened, wiU
discAiarge through the armature.
Startmg switches for motors starting under heavy torque should have at
least eight steps. Motoi^generator sets may properly be started with but
three or four steps.
As the starting resistances are invariably designed for intermittent service,
Btartiag switehes. except in power stations whoe an eleetrioal attendant is
in diarge, should be providea with a spring or other means to prevent the
■witch arm from remaining on an intennediate starting point.
0aad-Oi»enited lleBiete-CeBtrel •wlteUbeeurde. — Whct^
ever it is desirable to install a plant of moderate sise and obviate the
necessity of having any high potential conductors on the rear dL thie switch-
board, a hand-operated remote-control switchboard may be inetaDed. The
panels will have the same appearance on the front as any other hand-operated
alternating-current switchboard, but the rear of the pands may be made
nfe and accessible wiUi a neat arrangement of small wiring, inaamuoh as
all heavy conductors, meter transformers and aocenories are mounted apart
from the panda. A oonmion method of providing for the switehes and
transformers mentioned is to mount them on a separate framework in eome
distant place and control the switches frcnn the switchboard bv means <tf
bell cranks Jevers and connecting rods. These latter are usuauy made of
gas pipe, llie framework used to support the switches is usually utiHaed
to support the bus bars also. As the connections between the panel boaxd
and the switching structure are made by small seoondaxy wiring for meten
and instruments, and the bell -crank attachments permit oil aninmute variety
of combinations, the location of the switching devices may be selected to
best suit the station wiring so long as the oranks and toren can be arranged
to operate suitably and avoid total length in any single set of bell cranks and
levers of more than 50 feet.
CeMtral StatloM KlectHcally Operated
The concentration of energy in large central stations requires that the
measuring and controlling devices shall be concentrated also, in order to be
under the hand of a single operator and enable him to have abeolttte control
of the whole installation. This end is best attained by the use of electrically
opemted switchboard apparatus.
Electrically operated switchboards may be divided into two rlnmia
namely, alternating-current and direct-current equipment. As laise oentnl
stations almost invariably generate alternating current for distribtttion.
the deotrioally opemted switohboard is usually of the latter olaas.
ELECTBIGALLT OPERATED 8WITGHB0AKDS. 929
^■witohes used to control the oircuita may be 00 heavy that they
e easily oi»erated by hand.
Second, the location of these switehing devices can be made most oonven-
ient to the oirouits to be oontiolled and axMut from portions of the equipment
nrfaloh are liable to cause trouble, such as steam pipes, etc.
^hirdt in case of accident to any of the apparatus, the operator may be
locsfcted well awav flx>m the seat of trouble and is therefore not so liable to
be frightened or lose his head in an emergency.
^ouriht the entire absence of dangerous potentials at the center of control
provides absolute safety for the operator.
Fiftht the number oc drottits and amount of power may be such that the
control cannot be concentrated within a space of reasonable sise unless
electrically operated.
3x3^ it may be necessary that the operator be located a long distance
from the apparatus which he controls.
mtmUmamtj ef Ser«'tce. — When the choice of an electrically
operated switchboard is made, the next consideration is as to how much
AOpMatus to install to insure reliabilitjr of service. It is possible to carxv
tnis idea to an unneoessary refinement in some cases, where the chances ol
a ahut down are small and the consequences of it are not very disastrous.
On the other hand there are some plants where no expense must be spared
to provide against the oontini^cy of a shut down even of a very short
duration. The latter case requires much duplication of apparatus and great
flexibility.
Where a large number of feeders are used a circuit breaker is sometimes
provided to connect between certain groups of feeders on the bus-bars, and
is known as a noup drcuit breaker. Each feeder circuit of the poup has
ita own individual drcuit breaker to open automatically and relieve the
croup on the overload, but in an emergency the whole group can be switched
on or off the drcuit by means of the group circuit breaker.
The value of this group drcuit breaker for a single-throw system is doubt-
ful except in cases where transfers of load must be very rapid and a large
number of feeders are installed. It is more valuable in such a case on a
doublo-throw system, because it enables the transfers from one set ctf bus-
bars to the other to be made very rapidly and with a Twinimiim number of
•witches, as one pair of circuit breakerB will transfer an entire fl^roup of
feeders instead of having two drcuit breakers for each feeder drcuit. There
are four systems of copneotions for bus-bars commonly used. The first is
the singlfr-throw system, the second is the relay system, the third is the ring
ssretem, and the fourth is the double-throw system. Each of these may be
made more flexible by dividing the btis-bars into sections by means of
sectionalising switches.
Except in spedal cases it will be found that where any system is required
to provide flexibility, the double-throw system will be most satisfactory.
It is conddered the best practice to provide disconnecting switches
between all bus-bars and oil circuit breakers in order to permit a disabled
switch to be isolated and repaired without shutting down the system.
As the bus-bars form really the vital part of the system, it is necessary
that care be taken to insulate them so that short drcmts shall be'imposdble
and that trouble on one set shsJI not communicate to another.
Where absolute certainty must be insured against interruption of service,
all conductors should be isolated from each other and all adjacent material
made as fireproof as possible. In Larse stations this is attained by means of
masonry structured and barriers ana flame proof cables, with absence of
inflammable material for supporting the cables, using cells for all fuses and
apparatus liable to are and all oil-msulated transformers that are so con-
structed that danger from burning oil exists. This includes voltage trans-
formers which are oil-insulated.
The greater the energy involved the greater is the necesdty for isolation,
espedaUy in plants of pressures under 45,000 volts. The isolation is most
needed in heavy capadty stations of 2,200 volts and upwards, but it is rarely
advisable in stations above 45,000 volts, as small isolated conductors weU
•Of^orted in air will in such oases prove quite satisfactory, while barriets or
SWITCH BO ABDS.
Tra. 22. W.OOO-Vott RydK>-B1«otHo Ommtliic Btotion.
Svotioosl Etavatioo.
i
SWITCHBOARDS.
Hi
BUS-BAB AKD BD»-BUt 8TBUCTDBBS.
la ap the baekboDa of (faa
•houJd bfl antinly Jaolatwl f rooi mil duiHr from Kra, i
All !«<• alatktna aboold b« Ud out wlih k mdubk u — „ ,
to EuArd tsBinit inUmiptioa ol sarvlea frooi onlonMcn «na* uid to pro-
vldv a ZDAUV iriMnby cueuita flui ba inatelled uid oonnaotcd with faciUty.
oreta with aMfa bua-bw of opposlM potential in its own upanta oomr
pArtznant, wall aupported oo ponolaiii huutaton.
The ahdvaa or buricn in sueh k atniolura are usually ot MMipatOM or oon-
Btet«. Some of thae atniotana an oneloud antiialy. ooa aide hkvlni
mnoTmbls doon, while othera kre ouHla with the entire (Ida onn (or inipee-
tioD and facility io maldna oonneolioni and alterations. The bna-bara,
bang will proteeted and insulated, are luiuUy eompoaed rd bare ooppar.
For hi^er voltaces than above mentioned a different foim of bue-bar aup-
port ia lenenlly uaed. and the mnnectiona to the bua-ban an made with
wire or cable wall lupporced on auiuble lajutatora. D« * " *—
typioal airanxameata of bua-ban and oil awitohn follow:
8W1TCUU0AKD8.
BUS-BAB SIBUOTUBZB.
oirouit br«ak«m. Tha ^snenta nrs
tnnl intrk al brink or oooonW. On uoounC o( Ihic n
dooimbility of "■■'^'■t HHueetioai b«tw*Ba lb* npnuiil
BUd dinet nunnai, it ia snenUy naniMiry to build ai
<
<
Ofw aba** the otliar. DT if (BUcriaa kn not toba eomidend. then kbnaamant
niust b« provided to t^ln a portion el the ceer. The airapLnt awitfihboarda
an (uiiaUr doable desked, whila olben nguira thnn or four nalleria. For
a iLvao unount of mpfnrmtua, m double-deoked arreDireinent requina the
losnatasUeiiauid more nut«ial foe bus-ban. It is tbeiimplaat. bowarM',
ud cflen the moet eooTUHniasL when cbti sirlti^boerd sppenttia ia lookted
DpuiMotiiu oAbln. On the other hand, where the (uLariaa mutt ba ■oull* e
UuMdaok ■nrnncement ia more eiLtiafMlory.
SWITCHBOABDS.
In caoh pvtiBuUr aua tha aonditlcnu of ipaae. lenwrtbilitr. Mb., ma
daMnnlna the meat loiubtt pkoa tor the
Tb« HritB ud voltajit tmiur<n
bnakn, meten, Bto-. in almost i-^.j ««- ». ,
bat unoienunt dcpvodios upon Ifwal oooditit
n Uka ■uiiBtiir^ tk*
. . —When bairlvs an lucdCBsh aoodaetcr
im eonSiied to ita own oompartowDt and in oau <4 aoeadeDtal Eroond «
sbort-cimuit tha fluluriE or oorabiution u oonGnad to the oondaolor inTolTid
and pravantad fram datroyinc nBghborinc Knutootora.
Barrien. while fim-prtiof , mm not neosHarit; mada of inanlating matoiiat,
allhouch, war* it not tor the sipnue, chey might wntl be mMe of ludi
DutaHal. They are frequently made o( bnck. muoory. eoDeret& or lila.
lavorad material. It absorbs !•■ mdatur* than marble, but the inmlatiin
Btia-BAU HTBUCTURSa. 937
pfopertuv omnDot be dapBDd«d upon. The ooflt is a little lea. 8o&petoIM
la raulily obtnined in aoy rewoiubl* nt» or iIuih, uid la eedly diillad uid
out when fittini ii neoeaiAry at tlie plu» of erection.
When the burian and ooiupertiiiuiU of the iwiUiblxMRl ilniotun an
Dwds bom uiy of the ebove-nwntioiMd materUli, thiy (hauld be trCBtod •■
I. 29. Thne-Deok Oil anuit Breaker and Biu-Bar Strusture, Two 8eU
grounda irith r^emiM to hifh-tonaioa oiraaita. It tg true that vitrified
brick and mncrste. when very dry. an loor* in the natiue of Inaulaton tbui
Donduotun. but lite tandanoy of all auoh matariala. and even Hvpatone, la
' noie or leaa moiiture. prevmCiDg any abaoluU dapendmot bainB
Q than aa inaulatora, and all sandueton miut. thmfore. be inju*
pUiwdup
HWITCHB0A.BD8.
a, «u) «u^ pol« of a
. _ , , tmenl. Ibmiuy buiiM
Hpunts the Imdt from ths oil circuit brmken (« the biu-ban Bad lo lim
IB linet. Whsnver it a duinbla to u "
a UM idroiut bnkkan and the bue-tian o
)
outfoinc linn OD cirouita not exoeedinc 13.000 volte, thcee disoooneBtinf
■witches OD be mount*! lu ebDirn in Fii. 30, which ■tso itluatntee oM
C«lla .tar V«lMt:« "Amtmrmnmen amt Hue*. — In l^^taUr
liona of (hb nstun the voltage tnuuroriDen Bre ooDoected U Urce mMnm
of pi>w«r, Aod it beeonHfl neeeAeary lo avoid poerible demeie to the ijt
ton br «D* of them burnioc out; it ia theraore oudomaij to promt
BUS-BAB STKUCTUSE8.
989
Hum with endcwed fuses, the fuse and transformer bdng: Isolated in their
own individual cell in keeping with the practice of isolation which has been
deooribed.
When the fuses are installed as described it is often dedrable to dose the
odds with doors.
flDrli-TeaaloiE C^adafltovs. — lianafaetarers supply Mbber^nfeu-
lated cables for use up to a oertain voltage, which oan be rdied upon for a
long time in rMard to insulation; but it is a well-known fact that rubber
<leieriorates with age and the higher the voltage the faster the deterioration,
'vrhen conditions are favorable; so it is the best practice in all high-tension
installations not to depend upon the rubber insu*
lation, but to support the conducting cables on
porcelain insulators and keep them away from
all grounds and other oonductore. The insulation
on the cable serves, under such conditions, onl^
as a posdble preventive of troubles due to aooi-
dentu contact therewith. This does not mean
that the insulation is useless, as it might at times
prevent loss of life or serious troubles due to
aoddental contact.
Isolated cables laid against the grounded
structure or covered with lead are subjected to
atrainSf which mii^t sooner or later break the
insulation down.
Lead-covered, paper-insulated cables are sddom
used in high-tension switchboard structures.
Some of the best cables obtainable are insulated
with rubber. As the rubber, however, is com*
bostible and easily takes fire from flash, manu*
faoturers supply cables, when required, covered
with fire-proot braid of aslMstos. or with the outer
braid saturated with a fir^-proot paint to prevent
aoddental burning of the rubber cover. For
very high voltages, cables insulated with wrap-
pings cT impregnated cambric may be obtained,
with or without a flame-pnx^ covering.
The tenninals of cables used in the construe*
tion of high-tendon switchboards can be insulated
with any good material such as (»led linen ooated
with shdlao^ but this should not be rdied upon to
prevent {aceidentai contact with live tenninals,
and no attempt should be made to insulate for
safe handling, as the only time to safely handle a
faifl^tendon dable is when it is absolutely dead.
jnaaaa-Proof CoTorias** — In order to prevent the flame from an
are setting fire to the insulation of a cable and bang thereby communicated
to other cables or setting fire to the buildings flam»-proof coveritags are often
used. These coverings are always suppliea by the cable companies, bdng
purchased under spedfications which require that they shall meet the
reqmrements of the National Board of Fire Underwriters.
when inafjuliiig sucfa cablcs they must in every case be supported on
insulators, and not carried in ducts, as the flame-proofing a a poor insulator
and when saturated with moisture will serve as a conductor. For the same
reason the covering^must be stripped away from all live terminals a suitable
distance for insulation purposes.
Aaxillaiy JMract-Carreat Clrcalta. — The direct current for
operating the oil switches and other apparatus may be obtained as follows:
From aujdliary storage batteries.
From motor^^enerator sets.
From direct-current exciter systems or other direet-current bus-bars.
It must be especially noted that where the exdter system is controlled by
a Tirrill regulator, the voltage fluctuation is likdy to be so great that it cannot
be rdied upon for standara deotrically operated apparatus. In this case
dther a small storage battery or a motor-generator set must be relied upon
to supply the ener^. In oases where a storage battery must be employed,
owing to sudi considerations, and no charging current is available, a mercury
reotiner may be relied upon to charge the battery.
Flo. 31. Thre^DeckOil
Circuit Breaker and
Bus-Bar Structure.
Two Sets of Bus-Bars.
940
SWIT0HBOABD8.
)
r'^-^
/li^iyTW.
In eyaeg where it is absolutely neoenary to operate oil oirooii hrcmkm»
from direet-ouirent exdter Bystecns which are oonneoted up to Tiicill regia-
latoze, the ooUb can geQerally be spedally wound so as to operate at a k>w
voltage, and the mai^etio oirouit be designed to saturate at hieh voltngw so
as to prevent the switch closing with too much force.
C«B*MUtar mnA MmmtMmmfmt SwMeklbMivd. — Under thw bead
will be considered the installation of controUing switches and acoeaamiiM
that control dectiically operated oil switches.
In this connection it is essential to make sure that direct eurrent is rnvmSkaJblks
at a suitable voltage to operate the dectrically operated devices. Tte
standard controlling devices are desimed to operate from 126, 250 or 500-
volt circuits, but when the potential is liable to drop below 80 volts, operatiag
coils must be specially provided for the low voltage. The eontrolliiic appa-
ratus can be mounted on the face of the switchboard panel together with
the instnunents where the system is simple and an inexpensive atranj
is desired. Nearly all large stations have the generator-control afn
mounted on control desks or pedestals. A feature of some oontrol
is the use of miniature bus-bars with lunps and indicators in the dnmits. By
means of these bus-bars the entire mam station connections are embodied
in miniature on the controlling desk, and. if the indicators or lamps are
placed in the miniature circuits, the switching operations can be seen to ts^
place when the operator moves his controller exactly the same as they oeeur
in the main drcuit. When the desk tsrpe switchboard is used, it is iisaally
placed directly in front oi the instrument switchboard and the operator has
his oontrol apparatus arranged as neariy as possible opposite the respective
instrument panels.
Neariy every large installation starts with a few generating nnits and
Increases as the demand for power increases. For this reason it is desirable
that the structure used for carrying the contool apparatus be so desigiied to
admit of extension to meet future demands, or be
made in the form of pedestals carrying the various in-
struments. Quctk controlling table or pedestal shoald
Snerally contain controllers, indicators and lamps for
e oil circuit breakers, synchronising phigs and
lamps, voltmeter plug, electrically operated raeoetat
controller, a controller for the engine governor to
change the speed in synchronising the generators,
and a controlling device to open and dose the deotn-
cally operated altemating<;urrent generator 'ficid
switch.
The usual method of controlling feeder eireuita is
to place the controllers on the switchboard directly
beneath thdr respective feeder instruments.
C}eii«nit«»i^Cantrol !*•*— tala. — For aux-
iliary controlled switchboard apparatus, mountincs
must always be provided for the oontrol apparatus of
each generator. The pedestal shown in the illmtraF-
tion is deei[^ed for this purpose, and is used in com-
bination with an instrument post or pand located
immediately in front of it.
The pedestal as shown in Fig. 32 is designed to
take the following apparatus:
Signal lamps.
Six oil drcuit-breaker indicating lamps.
Three oil drcuit-breako* oontrolleiB.
One voltmeter plug and receptacle.
Two synchronising plup^ and reeeptades.
One controller for engine governor motor.
One controller for dectrically operated fidd rheo-
stat.
One oontrol switch for electrically operated fidd
discharge switch.
One control switch for engine sij{nal.
The controlling devices are not mduded but must
be spedfied separatdy, and may be sdected to suit the requirements of the
installation.
Fio. 32. Control-
ling Pedestal.
CONTBOL DESK.
941
C«»tr»lliair liMlKk — Wherever great oonoentratioii of cbntroDing
apparatue is neoeseary, a desk or benoh-bcNBtrd is often used. Tlue b usually
built of marble or steel, and special oonditions sometimes require speoiiu
desiKns.
This tvpe of controlling desk as shown in Fig. 33. has an iron frame enclosed
by paneled steel sides and a marble top.
Tht construction is such that each top panel with its correspondiite J^neled
sides forms a section, and the desk may be extended in either direction by
installing additional sections, the end |^els and end moulding being remov-
able in one piece to provide for insertmg the necessary additions.
JbMtroBient Poetf. — The instrument posts used with desks or
control pedestals are divided into two general classes, via.: swivel type and
stationary type.
Fio. 33. Sectional Controlling Desk.
These asain may be designed with suitable bases to mount jacks, or reoep-
tades. to enable one to calibrate or check up the meters, by comparison with
standards whose terminals have plugs to fit the receptacles.
A post supplied with receptacles for calibrating meters as described above
k shown in Fig. 34.
Oallbratter JTacka. — In many instaUations it is desirable to have
Steks or reoei^aoles provided in the series and shunt transformer drouits to
enable standard meten with suitable plugs attached to be connected in
theae circuits for comparing the readings of the switchboard meten.
There are two kinds of these receptacles used, one for establishing a loop
IB a series transformer circuit and used for an anuieter jack or an ammeter
juug receptacle, the other being a double-pole receptade or voltmeter jack
for use on shunt transformer arouits.
SVITCnBOABDS.
wheel g««r«d cfirectly
»mti4. — The i
■« puiejj finiahed h
>
■ulomslic. beioa uied oiil^ to trip b; hand
when the circuit ii to be mtemipted. to pre-
vent Iho »rc from humiog •■- '•'•' "
bM^en"""''™ " " "
providing I
loa Ap^mtB*. —
Fin. 34. Poat with nine
m meU?
opentedthrQUKh onndenHn » located Hut
The thme oepanitea and tar enauEh fmn ntigliboriDC
.— — -nil or on suitable BuppoMa new the
(eaentor. The pjug eondeneen if it ia difficult to propeHy nin the
«*itche» inthe base pel- leadii to the operating gallery.
mit tatini the calibn- KBlhtttatlaa ■wflckb*ar< B^bIb-
tiOQ of the InHtnimen^ BieBte. — Sub-eCAtiotia an mora eommoDlf
without ramoval. used for rail my Bervics. The unuJ aquipmeat
of awitehboard apparatus tor a aub-atatioo ia
snil aeiection of the eiiuipmeiit ia ehansed to acrae wiUi the requiramaBt*
of the caae. Aa tilting and power aub-elatioua are more or legs ipeoial it
ia impoHaible to give a deecription which wili be generally applicable.
Railway aub-aUtiona. however. fulGll piaotiBally the same purpoM and
in general diSer only in number and capacity of the units. The conduetora
the'niruTM short and'^"r«l aa poealbl?
A number of modificationa may be made in the apparmtua supplied.
lo aave eable and pernut of srealer coneetitnLtion. or for anuUJ atations the
■iMmatiDHHirreat switchboard may have hBDftiiparated eirauit bteakss
— unCed directly on the panels.
. .- — ■__! 1 ■LoK-ourrent railway systams. the satMtatioH,
houses and are very simple. Fu. 85 and SS
of this shanolf r. This ^iparatn* for lueli >
SUB-BTATIOM 8W1TCHB0ABD XQUIFHEHTS. 943
{
Fio. 35. Sui^e-FtMMAIMnuitiiit-CutTaiitSub-eutioaorTniulDRiur
HooM — End View.
8WITCHBOAUD8.
:>
8WITCHB0AKD IHSTBITHENTS AND METERS. 946
Power f Bolor fudintor,
Fnqumoy u
Dirtd CuTTtrit
GnLphJo ami
loiiH&tiiu V
Graphic dm
Gnphieir
oet OMS dfMrib* th^r dh. Int«-
J _ dM thn WBllliour output. Graphic
■ chut by K llnE the Siictustion of th« voltage, our-
liovD by the uiimat«r multipijed by
LElD-phfl^e cirvuitii-
. uaed only tor high-potential oirouite,
raoh M 20,000 to 100,000 volts. Tbey are conneoteddfrecliy to the dr^
ciuit without the interoeption of pot«iitia! transfotruBrB and do Dot tATty
■my curroit. CondenKn are somBllniea intcrpoged.
AIM>Bat>B|r-CarreBt iBstranieBta (or higlt-lension dreuitg sre
not connected directly to the circuit, but are uoed in eoiiDectJon with cur-
imt and potential tmufonners. Ciirrent trHmdonoen are coDDCoted in
aeries wilh the main circuit, but are wound for different ratios of imna-
usa tj( the currwit tr^oaformer ma.koi it unnecaraary to inauIaLe the instni-
ment for hi^ voftaeai and furthermore doee not nBcemitate ninnine the
hiEh-tenalon leads to the nwitchboard. AimneterB are Aometimea connected
Potential transformerH are usually wound b
on the seoondary and are used on circuits of above 000 vi
ajld other iostnuneata having potaxtial winding.
946 SWITCHBOARDS.
SINGLE-PHASE GENERATORS:
Minimum ammeter scale
K.W. X 1000 X (1 4- per cent overload guarantee)
voltage
Wattmeter scale » ammeter scale obtained from above X voltage.
THREE-PHASE GENERATORS:
Minimum ammeter scale
_ K.W. X 1000 X (1 -f per cent overload guarantee)
" voltage X 1 . 73
Polyphase wattmeter scale ■- ammeter scale obtained from the above
X voltage X 1.73.
TWO-PHASE GENERATORS:
Minimum ammeter scale
. K.W. X 1000 X (1 ->- per cent overload guarantee)
" voltage X 2
Polyphase wattmeter scale »- ammeter scale obtained from the above
X voltage X 2.
DIRECT-CURRENT GENERATORS:
Minimum ammeter scale
_^ K.W. X 1000 X (1 + per cent overload guarantee)
voltage
THREE-PHASE MOTORS:
Minimum ammeter scale
Horse-power X 746 v n 4. «• tn n\
" voltage X per cent Eff. X per cent P.F. X 1 . 73 ^ ^ '^'' **°* "* "*'•
TWO-PHASE MOTORS:
Minimum ammeter scale
Horse-power X 746 v /"i j. tn n \
" voltage X per cent Eflf. X per cent P.F. x 2 ^ ^^ "*" '*"" **"* "■^•'*
DIRECT-CURRENT MOTORS:
Minimum ammeter scale*- — ;- — t-ets' X (1 + per cent O. G.)
voltage X per cent En. '^ *-
THREE-PHASE ROTARY CONVERTER:
Minimum ammeter scale
K.W. X 1000 v/ij. ♦nn^
" voltage X per cent Eff. X 1 . 73 X per cent P.F. ^ ^* + Percent u.U-h
Wattmeter scale « ammeter scale obtained from the above X voltage X 1 . 73.
TWO-PHASE ROTARY CONVERTER:
Minimum anuneter scale
K.W. X 1000 y n ^ t o n ^
" voltage X per cent Eff. X per cent P.F. x 2 ^ ^^ "^ ***'" **"' ^-^h
By per cent overload guarantee is meant the i, 1 or 2-hour overload guaf
antee on the generator and not the momentary guarantee, although some
prefer to have scales calibrated to read momentary fluctuations.
The per cent efficiency and per cent power factor should be taken at full
load or overload.
The wattmeter ncales should theoretically be multiplied by the power
factor, but practically the scales work out better as given. Integrating watt-
meters have no scales and therefore need only have sufficient current carrying
capacity.
When the minimum scale is determined from the formula the next larger
standard scale, depending on the manufacture, should be selected.
P.F. — Power Factor.
O.G. ■■ Overload Guarantee.
GUIDE FOR 8WITCHBOABD SPECIFICATIONS. 947
The iDitial and ultimate number of each type of generator, motor and
feeder circuit with their voltage, kilowatt and frequency rating riiould be
civen. The overload guarantees of the machines and duration of same
snould also be specified. Other characteristics of the machine, such as ** Y "
connected three>phase generators with grounded or ungprounded neutral,
two-phase generators with inter-connected phases, direct^urrent generatora
with grounded or ungrounded negative^ should be clearly stated.
Flans of the building, or of that section of the building occupied by the
switchboard should, if available, accompany the specifications. It is essen-
tial to know the construction of the floor supporting the switchboard, and
it there is a basement below the floor, when oil switches, rheostats and other
similar devices are not to be mounted on the panels.
Specifications should be specific as to just what the switchboard contract
is to cover. Switchboards as furnished by the manufacturers usually do not
include the following, which should, therefore, be furnished by the purchaser
iinleas otherwise specified.
Complete flooring, sills for supporting switohboard and other pieces set
in the floor or wall for supporting cable racks, oil switch operating
mechanism, etc. All false flooring, if any is required.
All masonry work for oil switch odJs and bus-bar compartments.
All opeoings in walls or floors, with suitable bushinf^.
All elay ducts, iron conduit and other similar matenal to be laid in the
concrete floors.
Doors for bus-bar eompartments, lightning arrester or static discharge
comi»artment8.
All cable between switchboard and machines and between switchboard
and feeder drouits.
All bus-bars not connected directly with the switchboard, such as equal-
iser or negative buinbars near me machines.
If the purchaser desires to include any of the above material in the switch-
bofljxl contract, such material should be clearly specified.
A connection diagram showing the proposed main connections, providing
they are unusual or complicated, should accompany the specifications.
'Die height and width of the panels should preferablv be left to the discre*
tion of the manirfacturer. The thickness of the panets depends on the sise
(rf Uie panel, the material of the pan^ and the devices mounted thereon.
The design of the supporting framework need not be specified. In general,
statements in specifications can be made as follows:
1. '*The material of the panels shall be such as to afford the proper insula-
tion between hve metal parts mounted directly on the panel, for tne voltage
on iiduch the^ are used. It shall have a (natural oil), (black enameled) or
(poUshed) finish, and the panels shall harmonise in color and markings and
fit together in a neat and workmanlike manner. The panels shall be properly
supported on iron framework. Connection bars, bus-bars and wires shall be
property supported and insulated."
2. "AU instruments shall be dead beat and protected from stray fields
prodttoed by adjacent connections or bus-bars."
3. **Qrcuit breakers shall be of suflS.cient capacity to carry the overload
ampere capacity o^ the generator or motor, without overheating. They
shall faMB capable of opening under short circuited conditions without dan-
p^erously burning the contacts and shall be of such a design as to be positive
m action."
4. **€>il switches shall have a kilowatt rupturing capacity based on the
ultimate installation of generators as heretofore stated in these specifications.
The switdies shall withstand for one minute a potential test between con-
tacts and frame, of at least twice the rated voltage of the circuit."
5. **AU switches shall be of such capacities as to carry the one or two
boiin overioad rating of the circuits to which they are connected without
undue temperature rise, and shall be properly designed for the service for
which they are intended and without defects of workmanship."
948 SWITCHBOABDS.
6. '* Conneotlon baiB and wires shall be of sufficient eroos section so thmt
with TnaTinnim load the temperature rise at no point will exceed 40* C. nam
above the surrounding air, which may be based on 20** C. Bus-bars shaU
be of sufficient cross section to carry continuously the total normal load of
all the generators feeding in parallel through the busses at various jpoints.
The design of the busses shall, as far as possible, permit additions azui
extensions without materially interfering with the operation at a later date*
or changing the existing supports.
"Insulated main connection wires or cables should have flameHproof
covering, and the insulation should not be wholly relied upon but should be
supported by suitable insulators."
It is not advisable to specify the contact area, cross section or rating of
switches, circuit breakers or connection bars, as this often necessitates spedsl
devices, whereas standard devices could have been used if only the temper-
ature guarantees were given.
If purchaser has determined as to what instruments and switches axe
necessary, a complete list, giving the equipment of eadi iianel, should be
nduded. Otherwise this equipment should be specified in detaO in the
manufaoturero' proposal and inserted in the specincations forming part of
contract.
Switching devices in connection with switchboards can be divided gen-
erally into the following-named classes, vis.:
Switches for low voltage and small current are of tiie same seneral fonn,
though differing in details. In the main they consist of a blade of copper,
hinged at one end between two parallel dips, the other end of blade shoing
into and out of two parallel clips. The cups are jcHned to oopper or brass
blocks to which the circuit is connected.
There seems to be little uniformity among manufacturers regarding the
cross section of metal and stirfaoe of contact to be used. Perhaps a cross
section of metal of one square inch i>er 1000 amperes of current capadty is
as near to the conunon practice as any, and a contact surface for bolted con-
tacts of at least one inch per 100 amperes or ten times the cross section of
metal is also common practice, but will depend somewhat on the pressure
between surfaces. For sliding contacts Ihe density per square inch should
not exceed 75 amperes.
Auxiliary breaks are demanded by the National Gode for currents ex-
ceeding 100 amperes at 300 volts, and "ouiok-break" switches are now
quite common for pressure as low as 110 volts.
The rules on switch design issued by the National Code cover the require
ments well, and they must be followed in order to obtain or retain low
insurance rates; all switches must meet the requirements.
Blades, jaws, and contacts should be so constructed as to give an even
and uniform pressure all over the surface, and no part of the surfaces in
contact should cut, g^nd, or bind when the blade is moved. The workman-
ship should be such that the blade can be moved with a perfectly uniform
motion and pressure, and the clips and jaws should be retained so perfectly
in line that the blades will enter without the slightest stoppage.
. flparklnir at Swltolice. — In a paper read before the British Institu-
tion of Electrical Engineers. A. Russell and C. Piaterson discuss the subject
of sparking at switches. . In the diagram are given lengths of sparia at
various constant voltages. Following are the conclusions arrivea at: (1)
The spark at break ought to be taken as a guide to the rating of a switeh
for use on direot-curroit drouita. (2^ The shape of the terminals does not
make much difference in the length of the spark. ^3) The effect of inereae-
ing the speed of break above that ordinarily employed is small. (4) The
effect of a double break is to make the lengths of the spark the same as the
length of a spark with the same current at half the voltaije. (5) The dif-
ference in the length of the spark when copper, steel, or sine is used is not
great. (6) For small double-break switches for use on drcuits of 200 volts
and upwards, when the trailing spark just fails to bridge the air-gap. the air-
gap should be double the distance at which a permanent arc can De|obtained«
(7) For double-break switches for large currents under the same ciroom-
stances the air-gap should be more ihan double the arcing distanoe.
SWITOHIirO DEVI0B8.
949
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SPARKING AT SWITCH8S»
Fw. 37.
Switohins deyioes used in oonneetion with switchboards oan be divided
into severafolasseB as follows, vis.:
Circuit breakera, automatic.
Rdays.
Lever switches (knife switches).
Quick-break switches.
Plug switches.
DisconnectinK switches.
ControUins switches.
Oil-break switches (oU circuit breakers).
Fuses.
Ctrcnii Breakers.
A etrouit breaker is a device which automatically opens the circuit in event
of abnormal electrical conditions in the circuit. Automatic circuit breakers
are designed for alternating and direct-current circuits. Alternating-current
circuit breakers are usually made to operate on overload or low voltage.
The ufual oonditiooa under which dromt breakers operate are:
Overload.
Underload.
Reverse current.
Overvoltage.
Undervoltage.
Electrically tripped from a distance (shunt trip).
8WITCHBOAKD8.
« ipaabed it ii almys uodnitood that tli* firwloul
liwf. u rtivene lurreot. low-voltara fMtuna. ew,, uc
' ■ttAchnwDts b> ui« flt&nd&rd overload oirctut brouv.
* I used to prDt«ct Uie s
feature consiata al a coi. ow-
whioh opaiatea the dnniit bnakv
uii^'iui bn^ktf it ia oljviaus that tbe number of tuma <^ wire or bar on lb*
iu.t«u*l (inwrnls on the ampern capacity of tlie cinjuit brealier, Cimiit
viw lun wbTch 13 obtained by encirctiag one irf tbe ■tudn ij the dnuit
tiiuiLkar wilh an iron hDraeshoe to which is pivat«d the airaature. In onto
uwn. nrh circuit breaker ie dnigned to cover a torge ranee of eumnt.
b«IH«<n the timita of which It may be set to trip at praeliiailly aoy poinl.
^-h» liiniti of calibration luuail)' mngt from 50 to 150 per cent of the un-
liiiUKiu current carrying: capacity.
The llBJvrload cTmlt Breaker \r, irimilar to that for overiwh.
•imvl that it acts in event of an underload instead of an overioad. Thk
type of breolier is applied to itorBKa batter? circuits to cut oB the battery
wben the current falla (n an amount which would indicate that the hallen
,. j.._:— -v. . .1 ._„ ..._ Thounder^
jh ae if the (
However, it is not always
ibie to use an underload breaker for such p
my cas« on imill loads when not iiitendedto.
E Direct Cnrrewt Ile*er>e Carreat OlrsBlt
tiaily an overload breaker, having a polenlial wind
lit breaker would be required to opermle oi
urrent. Botti kinds of circuit breakers an
liable metbod is to apply a leveiBe oumni
SWITCHING DEVICES.
i«Uy u dnaribed on pass Ml to ■ Muiiiud ov«lo*d braakar, haTiac ■ ahunt
trip or loi^volun stUiduoait. In thia com the overload rgatnre mBy b«
Afljuated ind^wndentiy of tharevumfrcurrgatattaohmant, or may bo blocked
The piinoipnTuiw oC the revwM-eumnt oiKuit bnaker are lHlea]> da-
Bcribad under the luhjeat idayi on pace Ml.
The low-voltacfl feature b usually an attaohnumt to a atandard overioibt
bnaker, and ia uved ductfy on motor dreuits to cut oS n motor from the
Bouroa ol power in event of an Interruption ol ourrent, in order that tba
nutor may be properly atartod by the attendant, frith the aid o( a etsrtloE
itoml. The tow-
power la delivered to a ainile n
wly diapo«d, a ahott-cireuit upon one set of fmderB will be fed not only
through the portion of the feeder located between the ahort-cireuit and the
aourva d eupply, but abo by meani of the portion of the dunaged feeder
beyond the abort-circuit, with current Sowing in the reverae neniw from the
reeeivinf atatlon. " Overload" HKuilbreakBrBatbothgonerKtingand reoeiv-
iagendaottheoablearaimameanaof iaolatinglhedaniB^ tines. Their u»
uniniui«d cablea. which will be repeated until the cbroaged line ii Gnally
operation located at the receiving end of the trBngniission linee will autotnal-
ieatly aever the damaged cablte at thui end and prei-eot the receivinf aladon
from feedlDabiick into the short-circuit; this being attained without inier-
o( reedeiB of approiirnaiely the sune oapacily, ordinary overfoBd''ci'r<:uit
brcakera wiD cenerally afford ample pratei^tjon because a Hhort-circuit on
rectiTinc rtation circuit brcakera in parallel. Thia will tend to open (he
bnaker on the ahort-eimiited feeder line lirsi. and rrlieve the system. If
dwa not obtain and revena eirouit breakera are very (•■entlal.
962 SWITCHBOARDS.
The AnllcatlOTi of CIrcwtt Braakeiv to tk« y^if ctt— M
St«niC« lMtt«v7 IBooAten. — BooBtera of th« compound or series tjrpt;
if left oonneoted with the ssrstem when the circuit of the drivini^ motor is inter-
rupted, will act as series motors rotating in the reveree direction, and, if not
promptly disconnected, will attain a destructive si>eed. Similar oonditioBi
occur should the booster circuit be closed before the motor has been started,
or should the motor for any reason lose its field. Proper protection oBvdsr
these conditions is secured only by having an oveiioad and no voltage eireoit
breaker in the motor circuit interH)onnected with the circuit breaker in lbs
battery circuit in such a manner that the motor eirouit breaker must be dosed,
before the booster circuit breaker can be made to latch, while the opening
of the first-named instrument instantly causes the opening of the second.
Tli« ApFllcatlOB of Clrcvlt lireaken to tko IProtocUoM of
Booetora Boppljiog' W—Amwm* — Boosters employed to oompeoaate
voltage looses in leeders, incident upon transmission over considerMile dis-
tances, are either series or compound wound; if, therefore, when for any rea-
son the driving motor is not receiving current, the boostM* should be left in
connection with the system, it will run reversely as a motor; and in view
of its series field-winding will attain destructive speed. Tnis oonditiott
may be adequately dealt with bjr the emi>loyment of circuit breakers similar
to those prescribed for the previous section.
The low-voltage trip coil consists of a shunt winding connected aeroas the
circuit in series with a resistance, or may be connected in series with the
shunt field of a motor if used on direct current. So long as the voltage
remains constant the coil holds up a plunger, but if the volta^ drops below a
certain limit the pluncer is released and the force (rf the blow tnps the breaker.
The shunt trip cou is normally open-circuited, and when energLsed, by
means of a controlling switch or auxiliary switch or such device, it actuates
the circuit breaker.
GliiCIJJII? BMIAKBll 1»B«I«M. — IMract-Cmnromt Gir^
colt Bvookovs are made single, double and triple pole and four pole.
The double-pole circuit breakers usually have the overload feature on one
pole only, which is sufficient protection, except in case of the three-wire
systems where a triple-pole breaker having two or three coils should be
provided. Some types of double-pole brealcers have a coil to a pole.
Altomatiogr^on'oot Cireoit Sroakera are made single, double,
triple and four pole. The sinc^e-pole circuit breaker has one coil ; the douUe-
pole circuit breaktt* has one coil ; the triple-pole circuit breaker may have but
one coil if used on a motor circuit, as there is practically no chance of a short
circuit between but two of the leads, otherwise it should have two coils, and
in cases where the three-phase system has a grounded neutral it should have
three coils; the four-pole circuit breaker should have^two coils, unless the
phases of a two-phase systwn are interconnected, in which case it should have
three coils.
The carbon-break circuit breaker has been generally adopted for station
work on account of the fact that it requires minimum attention, and will
openkte many times on short circuits without requiring cleaning or repair of
the contacts.
The sequence of operation of the various contacts of the carbon-break
circuit breaker, is as follows: First, the main contact opens, which shunts
the current through the intermediate and carbon contacts, then the inter-
mediate contacts separate; this leaves the circuit through the carbon con-
tacts, where the circuit ia finally broken. The object of the intermediate
contact is to prevent an arc forming on the main contact.
Where it is desired to definitely direct the arc from the circuit breaker,
or the amount of space for the arc i» limited, such as would be the case in
car work, magnetic blowout breakers are preferable.
Circuit breakers of the carbon break type which are in most common use,
are preferably mounted at the top of the switchboard panels, as the arc
formed in opening is invariably blown violentlv upward, and is liable to
damage any apparatus mounted directly above (t, or blacken and bum the
panel. This tendency is not pronounced on small capacity circuit breakers
on circuits of 250 voitn or less, and thi» precaution is unnecessary.
GmCVIT liltKAKiiltM For Altoroottoff-Corroot Soi^
▼Ico. — The class of circuit breakers reouired for polyphase circuits larg^
depends upon individual conditions; the few cases considered here will sumoe
to mdicate the principles which should influence the s^eotion.
OIBOUIT BBSAKKBS.
963
In the oonnddration of polsrphase syatema, it must not be forgotten that
•• iiP P«^ijM>n of the generatora and motors are made with interlinked
windinjpi, and for this reason oirouit breakers for the protection of two-phase,
Ipur-wire generators and eirouits should, r»pudlera of voltage, provide for
the severance of aU four leads, as a single break in each phase stiU leavtt
the two rwnaining leads subject to a potential difference of not lees than
•eiven tenths of the voltage in either phase.
This point is made dear by reference to the accompanying out A. whioh
•hows two pieces of two-phase apparatus, as. for instance, generator and
P?^^ ??^°^*^..*? ***• •*?• circuit. On account of the windings being
interlinked. It wiU be seen that^the passage of current from one to the other
IS sUll possible, unless at least three of the four wires are severed.
Where, as is frrauently the case, the entire output of the two-phase
generator is supphed to single-phase transformers having independent
primary wmdinss, then it is true that in the absence of grounds or oxtMses
jyyyuuuuu uitinuii
WWWWii mrVmn
fm\ /WW
A B C
Fio. 30a. Girouits Oonneeting Polyphase Apparatus.
the generator will be fully relieved of its load by the opening of both phases,
each at one point only. Reference to cut B shows, however, that the possi-
bility of grounds or crosses is a contingency which in this esse needs to be
carefully reckoned with, as in the event of either of these conditions involving
both of the unsevered mains, the opening of the circuit at one point in each
phase does not relieve the eenerator.
Clrcaftte C^— etlay JPolraliAee JLpmmrmtwu, — In the event of
a short cirouit on the mams supplying a synchronous motor this piece of
apparatus, kept in motion by its own momentum, acts for the time being
as a generator, thus, much increasing the severity of the short circuit.
Again upon tiie opening of the circuit breaker the coincident slowing down
of the motor results in its E.M.F. droi^ping out of phase with that of the
generator, thereby ver^ greatly increasmg the total electromotive force of
the cirouit and producmg abnormal strains upon opening devices and insu-
lation.
Therefore^ the drooit breaker chosen should be such that when it is opcm.
not more than one main of the drcuit shall remain in connection with the
souroe of the supply. Motors operating on three-wire circuits of mod^te
voltage may be adequately protected by double-pole circuit breakeni. Those
^
9o4 8 WITCH BOA BDS.
OB taa^■lrin ■ystcnia fad from tnixfonnen whoM •aoondwica an not m
•IsoWinI eomwoIiaD may kba be im>tMted in Ihs mne muuier. Foar-mn
tnUBOiiiBioD olnuita miuin oinniit bnskcn of not Itm thui tbrat polw.
•to., but prrf«nbly the dtouit bmtken ohoMn lor tb« prolectioD of poli^
phant tmeratoci mad ffleden should be ompable ol ■everioi evory maui vf
the eirouit, thai aeouiinc oompleM iatanuptkni of the cumot rt^eiillmi ot
poiaible (rounds and amsa. Tha hichcr urn Toltac" of the dreuit the own
iTTinnrtaiit thii oouiidenitioD beoomcB.
le protootioii of polyphaie moton l> a subieot
ation. Tha staunoh buQd of thin cstaH of a]
Fio. •
hile , „
■ive diaturbanoce in the voltace tt tht
The heavy starting current rtiiuLred by many typca at polyphaee moton
brealun for (heir proiection, Thia difficulty ia ov«roame by makini tb>
connectiooB between the auto-B(arter and einmit bnaker msh that the Iatl«
wiUbeindiuled in Ihe drauit of the motor only whm tfaeBWitefaof thcaato-
ilsrter is in tbe nianin( posfdoti. RdetcDK to Fig. *0 ebowB how this im
be eBealed. When the dreuit breaker ia mnneoted in tha toanner thse
UDOu (he resultine overload, eg
ociiily lOHdad.
o epBed, (he drouit breake
lao be the caae should the c
...... *-i--:: """^
veiv [i^tty loaded, comi
witl be icHougty injured.
poUnt Buroe of damage^to^ potyrdiBae moton ia lit
CIBGUIT BREAKERS AND RELAYS.
956
Cmpmeity of Glrcnlt Breaker ]tM|«ir«d for D.C.
The siae of a cirouit breaker is ordinarily determined b^ its normal ourrent
oarryins oapadty, and for any generator the capacity of the oireuit breaker
should be the same as the normal rated oapaoitir of the generator, and the
breaker should be calibrated for such a range oc overload as is required by
the service oonditaons.
CapacUj of Ctrcaii Sreakor lioet ▲daptod for Motor
of Oiven Siso.
The Cutter Company.
The following table indicates the sixes of circuit breakers best adapted
for the protection of various sises of motors of from \ horse-power to 100
horse-power at volti^ges of 125, 250, or 500.
The figures given in the left hand column indicate the horao^power of the
motor at full load; the remaining columns show the normal eapadty of the
eirouit breakers required for each of the voltages given.
Horse-Power
of Motor at
Rated Load.
For 125 Volts Noi^
mal Capacity of Cir-
cuit Breaker.
For 260 Volts
Normal Capacity
of Circuit
Breaker.
For 500 Volts
Normal Capacity
of Circuit
Breaker.
»
4 amperes
• ■ a
• • •
1
8 amperes
4 amperes
• • •
2
16 or 20 amperes
4 amperes
4 amperes
3
24 or 30 amperes
12 amperes
8 amperes
6
45 amperes
20 amperes
10 amperes
Z*
60 amperes
30 amperes
20 amperes
10
SO amperes
40 amperes
20 amperes
15
150 amperes
60 amperes
30 amperes
20
200 amperes
80 amperes
45 amperes
25
200 amperes
100 amperes
60 amperes
30
300 amperes
150 amperes
60 amperes
40
300 amperes
150 amperes
SO amperes
50
400 amperes
200 amperes
100 amperes
75
600 amperes
300 amperes
150 amperes
100
800 amperes
•
400 amperes
200 amperes
liollailtlOB. — A relay is a device which onens or closes a local circuit
under pre-determined electrical conditions in the main circuit.
CSaMtflcatioa. — There are three general classes of relays as follows:
1. Signalling.
2. Regulating.
3. Protective.
MriialliiBg> Itolajs.
»a. — The signalling relay acts to transmit signals from a main
to a seoondary circuit.
Ampltcaaon. — They are mainly used in telegraph and telephone
work, oeing known by the terms telegraph or telephone relays, and do not
need further description here.
956 SWITCHBOARDS.
VvBCtlOM* — The regulating relay acts to control the conditioo of a
main drouit through control devices actuated by a secondary circuit, lliis
control may involve the maintenance of either the voltage, curreat, fie>
quency or power factor of a circuit at a constant value.
Appllc»tlam. — The regulating relay finds application in generator
and feeder circuit refnil&tors* such as the Tirrill Regulator, ete., in which it
forms the main device, all other apparatus bong subsidiary and actuated
thereby.
It di£Fere from the usual protective rdajr in having its contacts differ-
entially arranged, that is, so that contact is made on a movement of the
relay to either side of a central or normal position.
The regulating relay is usually considered a component part of its par-
ticular regulator and for this reason it will not be farther considered here.
Protectlre ]ftel»ja.
F«MCtl«B. •'- Distributing systems requiring more selective and flexible
protection than that affordea by the inherent control features of automatic
circuit breakers are equipped with protective relays.
Protective llelaje. — Protective relasrs are used entirely for the
Krotection of circuits from abnormal and dangerous conditions such as over*
>ads, short circuits, reversal of current, etc. They act in conjunction with
automatic circuit breakers, operating when their predetermined setting has
been reached, energizing the trip coils of the breakers and opening the circuit.
Anxlllairj Relaja, — Sometimes a main relay, due to inherent
limitations, is not able to fulfill all of tiie necessary requirements. An
"auxiliary** relay is then used in conjunction with the "main" reiay and
supplies the missmg functions. Such missing functions may be for exampJe:
1. Lack of time element feature in the main rday.
2. Insufficient carrying capacity of the main rday contacts.
CUMelflc»tloiA. — Protective relays are sub-divided aooordinK to their
particular function into the following classes:
Over-voltage^ overload, overload and reverae eurrenl^ revene eorrent*
underload, low-voltage and reverse phase. These designations indicate
the drcoit conditions under which the various classes operate. For examples
the oveav voltage relay operates when the voltage rises above a predetermined
amount; the reverse current relay operates upon reversal of current, etc
TlBie BleaieBt Veatare. — Continuity of service is an essential
consideration in all installations, and interruption of the service cannot be
tolerated unless the protection of the apparatus demands it. There are^
however, certain abnormal conditions of euirent flow which may exist for
a short time on a circuit without causing serious damage, such as swinffog
grounds, intermittent short circuits, synchronising cross currents, etc. The
simple instantaneous relay would in such eases act instantly and intermpt
the serviob unnecessarily. There has, therefore, arisen the neoessity for
relays having a retarded or time element action.
Ileflnlte Tlnae Iilnslt Ilelaj. — For certain service it is sufficient
that this retarded action have a definite predetermined value independent cf
the load condition. Such a relay is termed a "* definite lime" Umit relay,
Inveme Xime Iilmtt ]ftel»7. — For other service it is necessary
that this time element vary inversely with the load, that is, with greater
load the time element should be less, and vice versa. Such a relay is termed
an '* inverse time'* limit relay. .«« . • ,
Application of the Inetantaneoua Ifteiay. — Instantaneous
relays are used where it is desired to give protection only at the limiting
carrying capacity of the apparatus. . ^ ^ .
Application of Definite Time Iilnalt Iftelajr. — Defimte time
limit relays are used where it is necessary to maintain service on a given
circuit at all hazards for a predetermined time. This allows temporary
grounds and short circuits to clear by burning themselves out, and prevents
synchronising cross currents from opening the breakers. Most desirable of
all, however, it enables instantaneous and inverse time-element relays on
CIBCUIT BBKAKKM.
967
eontisaoiit drouits of loss impprtanoe to opemta and eut off under di»-
turbanoee without openinic the important drouit, even thoush the latter is
temporarily heavUy overloaded during the disturbance.
Cluinkcteriatlca of the Mmr^nm VlHie SleaaeBt SoIaj. —
— Inverse time element relays poaeess two valuable oharaoteristics as
follows:
1. Their operation is inversely proportional to the strain on the system;
the greater the strain, the quicker the relay will operate.
2. By virtue of 1, they act "selectively," those nearer a point of dis-
turbance in a 83f8tem, and which, therefore, receive the greatest load, oper*
B.tinK first, cutting out the affected portion and dealing the system wnile
connning the disturbance to a minimum area. As an example, consider a
system « three feeders (1. 2, and 3, Fig. 41) connecting a set of power station
bua-ban, Af with a set of sub-etation Dus-bars B, ana protected with auto-
matic dremt breakers controlled by overload inverse time dement rdays
at D, B. F. and reverse current inverse time dement relays at P, Q, R. The
overload relasrs will each be adjusted for operation at the same current; like-
wise the revene current rdays will each be adjusted for operation at the
■ame current.
Assume now that a short drouit devdops in 1 at point X. All three
feeders will at onoe oommenoe to supply euxient to the short oirouit from A.
D
C
M ■ "S
Fio. 41. lUustration of Selective Action of Inverse Time Element ReUy.
If B is a rotary converter sub-station, the rotaries, by virtue of thdr enormous
fly whed effect, may tend to supply current also, but as this has no par-
ticular bearing on the point to be Drought out it will not be further consid-
ered. D bein|( nearest the fault X, and therdore in the circuit of least line
drop, will receive more current thiin E and F. By virtue at the inverse
time law it therdore operates first or "sdectivdy," cutting off the feeder 1,
from A bdore E and F have time to act. Simultaneously P has been receiv-
ing current in the reverse direction through bus-bars B, from feeders 2 and 3,
and has out off feeder 1 from B. Q ana A will not operate as they receive
current only in the normal direction, and E and F will not operate as the
fault has been isolated and they have been relieved of thdr overload before
they have had time to act. In actual practice on alternating-current drcuit
relays P, 0. E will operate on both overload and reversal of current, and
are so designed that the operation on reversal of current is at a much lower
value than on overload (about i to | in representetive types). If overload
and reverse current rdays were used at P, Q, R, the relay at P would operate
bdore Q and R. for the reverse fault current flocwing through P is the sum of
the noxmal fault currents through Q and R.
Where only two feeders exist as, say 1 and 2, P and Q would each recdve
the same amount of fault current, and the selective action is not so great,
but is still amply sufficient to allow P to operate bdore Q, on account of the
difference between their reverse and overload tripping values.
958 • SWITCHBOARDgC
Similarly to the definite time element relaj;, the invene time element nlay
will allow temporal^ grounds or short circuits to dear themeelvee and vm
prevent synchroni«ng cross currents from opening breaken. HusaetiiMi
18 somewiiat more limited in the latter on account of the inverae feature,
but is quite sufficient for all ordinary conditions.
Heolaaiilaai of thm Protective Rolaj. — Protective relays in
tiieir simi^est fonn oonaist ol three elements:
1. The actuating meoluuusm energiaed by the line aouroe to be pro-
tected.
2. A set of contacts operated thereby.
3. The time element feature (where present).
Aetuatlnin' MochantaiWi — The actuating medianism aasumes the
form which wiU pve operation under the desired conditions. It tisually
involves a motive device consisting of a solenoid and oore, a rotatins motor
m some form of instrument movement.
tfwkpiping JMoclinwIewi. — This usually consists of a set of movinc
platinum, silver or carbon-tipped contacts engaging a oorrespondins set of
stationary contacts. Some rda^ have sini^e contacts for dosing a single
tripping drouit; otiiers are provided with multiple contacts for dosing two
or more tripping drouits, as in the operation of double throw systeons where
a rday in the main circuit has to operate drcuit breakers in each of the
dujdicate feeder bus-ban.
KImo SloaiOBt Mecbaniaat. — In this instantaneous relay aS
retarding mechanism is eliminated, the relay actinsc ptacticallY instantane-
ously with the application of an excessive current. In the defimte time limit
rday it is the usual praotioe to employ an fur dashpot, such as used in are
lamps, to the pbton of which the contact mechanism is attadied. Upon
the operation of the actuating mechanism the contact mechanism is rdeased
and allowed to descend by (gravity against the action of the dashpot, th«^y
making contact a definite interval of time after the disturbance and inde-
pendent of the majsnitude of the disturbance.
In the inverse time limit relay the actuating and contact mechanism is
attached directly to an air bellows and upon operating tends to oompress
the bellows against the action of a spedally oonstructea escape valve in the
latter.
The amount of the retardation varies invecsdy with the pressure on the
bdlows and} therefore^ inversdy with the magnitude of the disturbance.
An alternative arrangement replaces the bellows with a conducting disk
cutting a magnetic fidd, in which the retardation due to the eddy current
reaction, induced on moving the disk throufi^ the fidd, varies inversely with
the magnitude of the force with which the disk is urged through the fidd
and hence inversely with the disturbance.
Shiuit Vrip OoMtact*. — The usual airangement of rday oontaefa
provides for thdr dosure upon the operation of the relay, in which case the
relay is spoken of as bdn^ provided with '* shunt trip contacts." Tlie con-
tacts are connected in senes with the tripping drcuit of the brealrer and
an independent source of current, and upon dosing enerf^ the tripping
drcuit and open the breaker.
The tripping coils are wound for shunt operation from the independent
source which is usually a direct-current exciter drcuit or a storage battenr.
and the circuit breaker is spoken of as bdng equipped with shunt trip oois.
The operation of shunt tripping coils from the drcuit bdng protected is
inadvisable, owing to the liability of the trip coil failing to operate on the
low voltage existing under short drcuit ana overload conditions.
ftovioa Trip Contacts. — Where an independent source of current
is not available the drcuit breakers are provided with series tripping ooils,
wound for operation from series transformers in the main drouit. Overload
relays are also provided with series trip contacts which differ from the shunt
trip contacts in being normally closed instead of open, and opening upon
operation of the relay. They are connected in shunt with the senea trip
coils short drouiting the same. Upon operation of the rdav they open,
allowing the transformer secondary current to flow through the tnp coils
and trip the breaker. As there is always suffident current flowing under
overload and short drcuit conditions to operate the trip ooib, this arrange-
ment is as satisfactory as shunt tripping.
V
\
V
CIBCUIT BREAKERS.
M9
I •r AltonuitlBr-OvrreMt •ytifiii , -^ Tha
Hon of raUys to an^ given system depends almost entirely upon tbie local
eonditions en operation, varrins somewhat with each installation.
d«m«niior CiPO«M ProteciUrai* -^ Representative practice leo-
i>inn*f«**^* the placing on generator circuits ol either a reverse cuitent
iday, with a time element f eatureb or dse the entire elimination ol automatio
piotcMSiion.
W99^9w Givcvtt Protocttoa. — For feeders at the power statSoo
«nd, overload inverse time element relays are desirable. For feeders at the
aub-station end, overload and revene current inverse time element relays
are desirable.
Kotarj CJoMvertor Cliwli ProtectloB. — With rotary convert-
ers, an overload inverse time limit relay in the high tension side of the
power transformers will give protection for the alternating-current side.
For the direct current side a reverse current inverse time limit relay operating
the direct current breakers will be required.
gg^fcttay Vomr-Wtre Vlir««-PluM« djetem. — An example
of the relaying required in a typical four-wire three-phase system is illus-
^olMMtlb Oil OUmU:
' with letejra.
Kentral
aroeadsd.
--^
--©*
A.O.
DistrlbetlOB
-i#-
C
■4^
r^
B
■*f-
iofMft
ties
fi !(' ' o^-"*—
Diattl>
^Uoa
OuteabvUkiv wlUinlam
Fio. 42. Relaying of a Four-Wire Three-Phase Bsrstem.
trated in Fig. 42. Three generators operating with thdr neutral pcrints
pounded through a resistance, feed a common bus ssrstem, four sets of
feeders, power transformers, rotaries, etc., for alternating-current and direct-
current distribution of power. Automatic circuit breakers are inserted
operated by relays as follows:
At A, A.G.
At B, A.C.
At C, A.C.
At D, A.C.
At B, D.C.
Overload and reverse current inverse time element relays.
Overload inverse time element relays.
Overload and reverse current inverse time element relays
Ovoioad inverse time element relays.
Reverse current inverse time element relays.
The relays at A are intended for reverae protection only and so have their
overtoad adjustment set at the mitximum value.
SWITCHBOARDS.
■■It aBaittoyed,— TlM typa* of pioM«ti*« nkn
D.C. Oveivvnitace ralayi.
D.C. Haver™ cunwil nitan-
D-C- £x>1r-volt4Cfl relayH.
D.C. UndtriDwJ mlnyi.
A.C. Overioul rel«y».
A.C. Overlowl and nvene oamot raUiiB.
A.C. Lowvoltan raUn.
AXl. Bav«ne phsH rahyi.
Si--
Fto. 43. 'WatinsbouH DlnctCunwit UmB Limit Rdky DiAniM Tin*
. at' aver< V*ltaa« Relar. — TIib dinet-omrait otk-
votUc« relky i* us«l Dhicfly on baitery cbiinniii paneli. but ia aJsi laid
age from exceAs voltage. Tn storaffe battery work the nlay m&y be laed
to diflconnect tbe battery from the circuit when it ig fully di&raed, as undH
certain welt-de6nad ooadiltoiu the vnltaie nf the battery ii a meuun al
iU (duTgfl. The VDllaxe of a bBtl*ry ii dependent, homrer, not only on
BBLATS.
961
pcmuoMndy change the Uw of a battery'a voltage eurve. and an over^yoltace
relay set for a 0ven full ehanro condition may aotually operate when the
battery ie not at full char^. The proper settinc of a relay on such a cireuit
is, therefore, a matter entirely to be determined oy the operating oonditione
and with fiul conaideration being given to the effect upon the full charge
voltage of the charge and dischaige factors.
IMrect-G«rr«Mt ll«v«ne Currmmt Wt^lmj, — The direct-current
reverse current relay is chiefly used for the protection of storage batteiy
installations and rotary converters. When applied to rotary converters
operating in parallel the relay serves to protect i^ainst short circuits ooour-
nng on the alternatini^eurrent side of the rotarvt on the dkeot-ouxrent side
between the rotary and relay, or in the rotaiy itself.
I-
Fio.44. General Electric Alternating- Fio. 45. General Electric Alternating-
Current Overload Relay Instantan- Current Overload Relay Instantan-
eous Action Shunt Trip Contacts. eous Action Series Trip Contacts.
Short circuits occurring on the direct-current side beyond the relay are
taken care of by the circuit breaker overload coils. When applied to
storage battery installations the relay prevents the battery from discharg-
ingback into its charging source. ...
Tlaa« BlmsiMat ]r«atore, — When synchronismg machines to^ a
system operating a rotary converter, momentary and harmless corrective
currents are liable to flow toward the rotary on the direct-current side. In
order to prevent interruption of the circuit by such flow, where reverse
current relavs are present, it is necessary that the latter have a time element.
This time element must oe of the inverse order to give ^uick interruption
on overioads and short circuits and to give a selective action so as to cut off
affected drouits.
Orentpe^dtec o' Rotaitea. — Reverse current relays are not a
eomi^te protection against the overspeeding and running awav of rotary
oonverten such as would result from the opening of the rotary 's field. They
should be supplemented by mechanical ovenpeed devices attached directly
to the shaft of the rotary and arranged to close the trip circuit ujran operap
tion. Such additional precaution is necessary as very low reverse currents
exist under sneh conditions, only sufficient to supply the losses in the rotary
and less than the minimum setting of the ordinary reverse current relay,
which will therefore fail to operate and protect the machine.
lMr0ct«Gmnr«Mt Ii«w- Voltage Ilelaj. — This relay is generally
used in eonnection with direct-current motors and operates when the vol-
tage ai the cireuit falls below a predetermined value.
SWITCHB0ABD8.
■■« Vnd«vl*ad Belay. -
rkii rday is nwinljr laad
In (b<ehBrciBs<rf«tora«ebatteHalodisooiuiKt thebi.t(«ri« wt...
AIMrBai£Hr-V>rnM 0*«r)*ad a*lB7- — This relay
Twy mtleomvely, nuinly (or the promotion tjt f—^—
mMan and tnuutormen. All Uires forma eiiat
dofluiM time limit mnd inverse time limit, eaoh hut
»m ouUinad in tha prerading pages- Blther senes
provhlad depoidiDc on the trippine source.
AWarMaM^iOMTWrt OvdrivaJ aMI 1
lur^^Thls relay is an important one, very exif
and feeder pnitaotion. Itexiits only in theinver
used (or geoentor protection the overlosd luUiu'
mom value to clva overload protection only a
u spedil sppliflativi
Imiun oairyinc
)
I 47. Wcetinfhouse Alteniatlnc-
lurrent Ovariouj RtJav (Cover Ra-
noved) taverae Tims Umit Action
oapsflity of the generatoi
Lhis relay hai been onvered in the_preoedin| paca.
at lAw-VoI(ar« n«il*r. — 'Hiis type cf tday
n of induDtion molnra sRHinit a fall in the liM
a( HavorHi-Pkiwe Rslay. — Tbia relay is
u.<iw vi praieci Hyncnronous apparatus affainnl a revena] of direetion of
n^ratinn or phiue prosreHJon nf the alleTnatine-currenl aouree.
Bcmvtv-Cmtrol Swltcbee for B^BBllaer ClrcBlla In hufe
'iffi,
DISTANT OONTBOL SWITOBKS.
Tb«ri«6l
3.0O0. Ths upper tsj
eciuaU(«r duId, iridob Ukm tha pUoe of the aqua
*t the ■wiletiboud. Tha lower lermiiuJ of ai
spprvprimCe termioal of the aariaB wiDdinc of tl
Tba duaiac at aaab awitch. Uianfore, aomplel
lacti with (ha
■7& (h*
4
(
Flo. 48. Ramala-Conti
I Switch (or EqiuUaer CSrsuitt.
iwitahbiiknl looalad i
unHnt nf ■ 4mAjl doi „.-
ipeninK ocnI, uid upan
for oontrnl (n
eSaatad by thi
ment, the doalDE ooiT Badi switch' _ .
mechAnifljii. ao that it ean ba opatAtad at
■(•▼•r •wHvksB. — Lever ■witahee
eumot dreuita up to SOO vulia. The deei
oovered br the "Fire Daderwritan Codi
repraMoU typioal lever awitoha. It aho
a diateDoe, such control bain^
'" ■'""iw awitch, brlD^ng into
.- ..;b a DAad-oLoflitic
plain knife blada awitchca
250 voitf and on altaniRtjng-
theaa switchH la thoroughly
The aocompanyins diagram
SWITCHBOABDfl.
oHMdtr ol ISOO uniMna io ■ aiiifl* (wiMh te aboiit •> Uah
__ i__.j :. :..L B EibU to b» loo h«nl for tb
M ii pi»etioal,_»» haaviar^MiMmty
n
^MCi
Fia. SO. SOOO Anpan, aP., 8.T.
lie quick break airiCah ia (
—.ii— , ., „ driven foUowM bl*d« which r
(1m eUp« aftM the baId blula Invn ud ia opened quiakly by m
Q,Hleh Sreab SwUckas. — Tlie quick break airiCah la aMantuIlT
" ii provldsd witb gpring-driven [oUowai bl*d« which nautioa io
PLUO TUBS SWITCHES.
Inc; th* object beioc to bnak ths oinmit qulekly m
th* bnnilL. _
iiut«ad <d tbe bwId blade,
but ft qiiiok bnftk Bwit '
Tbe degicn (< ■ qi
WTJt«r> Code." A I;
diunuD.
lug OP ihs uH ud the i
qulekly and thereby Iaboh
I follower take lb* buniina
er iwium may abo b« opomd qidekly
I auDoi oe opoied sUiirly.
k bn^ ■witsh ia sovand by tlie Tin Uiider-
ioal switoh ia illoatratad in the a«oorapuiyinB
~ Tbe plug ewftflh hai numy fonn* deiMad-
pany mimufaiiMirlBt It. Tba prindpta ot a
«1P) i
Plui Tube Switiih. ^
Fio. E2. lO.OOO-Volt 10-Ampere Plui Tube Switiih.
plus tube ■witch ia to niptura the drauit in a tube which is eodoaed at one
enoT thereby Donfining the are and limitini the eupply of air. Flu*
'[due Bre also used for trvnaferrins live aiTouile and for voltmeter and
iCflhea nuy be oved
flireuit4. the 01
!>□ hi^ voltase drcuita providlM the
beinc uaed exteoaivdy 00 lOOOO to
irrent ivi(lnf from 4 to 7J> amparei.
i
Fio. S3. 16,000-Volt SOO-AlDpare Front Coi
966
SWITCHBOARDS.
The form of switch is similar to the low^volta«e lever switch ezoepi that
it is mounted on insulaton. It is not intended to open any load, with a
possible exception of the magnetising current of a tninsf ormer. ana should
not be used for such purpose. Howeverf it should be thorou|dily insulated
for the voltage of the circuit to which it is connected and should be capable
d oarr^g the maximum current of the circuit. Disconnecting nwitrhm
for high voltage circuits, such as 60,000 volts, are designed with a view to
rigidity rather than current-carrying capacity as the switch becomes vecy
large and the current oonespondingiy smalL
Fro. 54. Rear Connected 300- Ampere Sd.OOO-Volt Disconnecting Switch .
¥
Fio. 55. Front Connected 300-Ampere SS.OOO-VoIt Disconnecting Switch.
Disconnecting switches have the following vxdtage rating:
r6,600-16,000
22.000
Voltage \ 33,000
i
45,000
66.000
These switches are made single pole only and are <^>erated by means of
a long wooden handle provided with a hook. This handle acts as insula-
tion between the attendant and the switch.
CIRCUIT BREAKERS, 967
SwiteUM for KliTli Poteaitf »U.
Typos. On American high-toision tranamission lines there are four
seneral types of switches now in use:
(1) Switches designed to break the circuit in the open air.
(2) Switches designed to break the circuit in an enclosed air space.
(3) Switches designed to break the circuit with the aid of an enclosed
metal fuse.
(4) Switches designed to break the circuit under oil.
Type No. 1. The large amount of space required by this switch, in order
to be certain that the arc will be broken, makes its use limited and it can
be used only with safetjr when the line potential is comparatively low for
the reason that a circuit containing inductance and capacity may have
very hi||[h-voltage oecillationB set up in it bsr an open air arc unless the
current is broken at sero value, resulting in highly increased voltage.
Type No. 2. This switch occupies less space than type No. 1. but its
effect on circuits containing inductance and capacity ia verv little different,
80 tiiat there wiU be the same oscillatory rises of potential on opening the
circuit. In addition, the explosion on opening heavy currents with this
switch is at times so heavy as to endanger not only the switdi itself but
all d^cate instruments in the immediate neighborhood.
Type No. 3. Two forms oi this switch have been more or less used.
In the firat form the fuse is connected in parallelj and in the second in
series with the current-carrying parts of the switch. The first form is
limited to low-voltage circuits, because of the unreliability of the enclosed
fuse on comparatively high potentials when the circuit is fed from large
oentral stations. The second form operates through the severing of a
metal fuse within an enclosing tube filled with powdered carbonate of
lime or some other non-conducting powder. The end of the fuse is drawn
through the tube by the moving arm of the switch and the circuit is opened
without serious commotion, if the switch has been well designed ana care
has been taken to properly fill the tube. This switch will open safely
almost any circuit at almost any potential, but like the open air switch is
limited by the amount of space required, and the jx>wder set flying by the
explosion of the arc is a decided objection if there is any moving machmery
in the same room.
Type No. 4. This type of switch is almost universally recognised aa the
only switch suitable for use upon high-tension circuits.
^ It has been shown by numbers of experiments that the opening of a
circuit by an oil switch is not a quick oreak; the oscillograph shows that
the effect of the oil is to allow the arc to continue for several periods and
then to break the current, as a rule, at the zero point of the wave. The
result of the brei^ng at this point is that the opening of any circuit with
oil switches is rarely accompanied b^ destructive rises of potential. An
oil switch creates less fuss in the oil if it is opened slowly, but it is also true
that an oil switch for 40.000 or 50,000 volts must have a depth of oil over
the terminals of at least four or five inches. If less depth of oil is used,
the oil is likely to be thrown out of the oil pots, on the opening of the
circuit, although the arc will be broken.
On the assumption that the oil switch is to be used for high-tension
work, the followmg points of construction will bear consideration after the
Xiarticular form of oil switch has been selected:
(1) Rating. The performance of the switch under abnormal conditions
of a low resistance snort circuit should be considered as well as the capac-
ity of the switch under normal operating conditions.
(2) Oil. Any good paraffine oil will answer, but it should have about
the following characteristics: flashing point not less than 180° C; fire-test not
less than 200^ C; specific gravity, .865; acid, none; alkali, none; evaporation,
negligible.
(3) Insulation. The insulator and insulating bushinei should be either
mss or porcelain. The switch should stand a break-down test between
the live parts and the metal case and frame work of at least twice the
working voltage applied for one minute. The external terminals should be
far enough apart, or sufficiently well insulated, so that there can be no possi-
bility of the current striking across through the air from terminal to terminal.
(4) Location. Oil awitdiM tor UM oD dnuili of above 6000 Tolts ahooU
« placed at a diatanee from tha ■wit4jhboard and away from tfao sBocn^
DC aod tnuufomiiiic appantua. Bach pole iboulil b« plaoed in a aepaiaM
ir«-nn>of nil, so that by no po«ibility oould an arc or oxploaion ia nji* A«Ji
immunioaud to another ocll, or Co the naiihboriiia maehioMy.
"-"---' -' lion. AU —■■-'- '-—'-' ■-- -"■■
(5) Method of operation. AU awitohca should b „ ,
or electrically aontroltad from a central ■wiCchboard, and all the polea of a
Builch should be operated ■imultutaouiilr. Whau equipped mlh nla*
for opening automatically this Bwitch beoomca one of tiie boat forme a
eircutt breakert, and is so designaled fay the Weailocbouse CompaDy. It
ia alao desinble Ui equip each switch, eapeciaily if it is automatiCi with ■
time fdemenl attachment, bo thAt the circuit eanuot be opened for at laaeC
Following are cuti i^ oil switches for diSsrvnt purposM attd potantialB
Fm. Be. Type C Oil Circuit Breaker, Showing Oil Tank ai
CIRCUIT BRBAKXSS.
Ktatwn.
'hr™dr
TV
nM poBibli
^tbe"
ultiDwM brnkiu ca
ity
tllB(Vl«
st«d
them, uid I
the rule.
."SSi,
g iiw(«]|i<d .on
HitohM whioG
^«BtlBrkou« 'Trf C oil Clrcnlt Bnkkcn. {Flo>>«.M.)
This eireuit bmlur will open cirsuita uiryins the hesvieat eumoU
in(x>uDt«nd In modem pnuiUce.
It ia dewsDod for operfttioQ <m oircuite up to vnd iaduding 3A.000 volu.
i
Fia, 67. Type C Circuit Breaker, Side
end will oanr tbn nomul curnot at ZS oycteB, n
exceeding 25''C.
Evih pole Ifl encloeed in a eeparate compartm
Dlo»d bj meeni al k salenoid and opened by gnvi
:>
aWITCHBOAKDS.
Hounl«d on ausb dioait bnaker Ei ■ rdi
avit«h la opflt*it«d by tha motion of Ihe leven
for the indinlins ud trippinc dreuita, >l»
lo«lda| tha nirouita when required.
«Hk. liull«ttD« Uut iwltch la
Fio.58.
Fio. GB. DiacnuD of Conneotioni. 3-Pola Electrically Op««t«d Typ* C
Oil Ciniuit BrealMt.
CIBCUIT BBXAKBKS.
Fta.flO. DiaciminatCoiuMintoiB. 3-Pate EtntrioaHr Opostod Noar
Aulomiitia. C Oil Cirenlt Breaker.
iraaMBCksBM T7V<| ■ Oil ClFCBtt Kraaber.
The typ« E droult bnkkin are nutd* in the elHtrlcalljF optntei fon
for polsntiali rrrnn 3,S00 to 35.000 volts. The ultimBtn biwkinK upuit
al tCij brsaker ia B.OOO k.w. for single-phaaa, 13.000 k.w. for tiro-phsH an
10.400 k.w. for lhn*.phB*e eimiits.
A ninpl* antam ot tooln and Isthb is mouatud on th« top of it
bnaker, and a pointful ttMtniDUiciiM it arranged with Its mavabls ooi
i
Pia. SI. Sinfle-Pole, Type E Oil Ctrvult Brwkar.
H bi^ikar, and
A trippin(-ooil ii also mouoiAl with the
.t email liocle-pole. double-throw switch is mounMd
■ cqMimtsd by the motion cf the levw in openins and
972
8WITCHB0ABDS.
elosing the oiroiiit; it oontrols the tell-tale indioator sad lamp wliioh an
mounted in view of the operator. These circuit breakers are opeimted hw
125. 250 or SOO-volt direct oarrent, and are calibrated for 25 cycles.
The electrically opemted type E oil circuit breakers are made both ixmh
automatic and automatic, t(e latter being operated by means oC overload
relavs.
The breaker is made in siaffle-pole units, each being mounted in » brick
or concrete compartment. Two, three and four-pole combinationa aze
made by placing these units side by side. The tanks are of a derign aizmUr
to those of the type C circuit breaken.
Oil Awttcli Stractiirea. — The structural work for tjrpes C or S oS
switches may be brick or concrete.
When the etrtieture is of brick, it is neoanary that the anchor bolfia
)
)
Fig. 62. Diagram of Connections. 3-Pole Electrically Opemted Type E
Oil Cirouit Breaker.
outside of the brickwork. When the switch has a concrete base, howerrer,
the bolts are usually anchored in the concrete. The only soapetone sup-
plied with the type C oil cirouit breakers is the top slab, the blocks to hold
the terminal insulators in the rear, and the soapetone barriers between
these terminals.
^fr«atlairh«iue Type O Blvctrlciillj Operated OH
■XK
lit
This tsrpe of circuit breaker is supplied to operate on circuits up to and
including 60,000 volte^ and to carry continuously currents up to and in-
cluding 500 amoeres. It is designed to open the circuit on any condition
of overload or snort cirouit which may occur wi^ a power station capable
of delivering 200.000 H.P.
Elaeh pole of the switch gives a double break, each break being approxi-
mately 17 inches. The closing magnets require approximately 5,000
isatts direet current, while the tnpping magnets require about 300 watts.
CIBCUIT BBXAKBB8.
973
The oO tanks, three in number^ are made of boiler iron, lined with an
Inaulating matenal with barriers mterpooed between the stationary oon-
tsusts. 'nie leads with their insulation and the upper porcelain insulators
ky be removed from the switch, giving access to the contact parts for
stion aatd repain. The top covers of the tanks ars made of soapstone
The total weight of each three-pole switch complete, induding oil, is
approximately 16.000 pounds. The oil alone weighs approximately 4000
pounds.
A two-pole, double-throw indicating switch is provided upon each three-
Fio. 63. Type G Oil Circuit Breaker, Thf«»-Pole.
pole oil switch for use in connection with the controlling and indicating
devices. The circuit breaker is not automatic in< itself, an overlcMul relay
operated from series transformers being necessary.
IFttatlarliAV** V7P« ^ Oil Circuit Breaker.
These oU circuit breakers are designed for mse on circuits of limited
capacity and high voltage. While they are built for use on circuits up to
and including 88.000 volts and with a carrying capacity up to and includ-
ing 200 amperes, they are not guaranteed to open euvuits whose maximum
capacity exceeds 20,000 to 25,000 k.w.
The tanks of these drouit breakers are of wood*
FN. M. TnM L ElMtrtoaDy OtxnMd OU Onoit
VIS
•11 GIrcBlt-Braaliar C*Btr*ll«r. ^ Thia nrntnUing nritah ia
ot tli« drvm typA with k hinged handle, which, when tiirowD to the open
poution, msy bs looksd by iwinEmE tlifl handls outmrd » that it ia Id
has with the drum ahaft. It aannot be locksd io the oloud pniilioD.
When the hudle a niwd u daaiibed it iadicKta to the operator that tha
awitoh ia out of servioe. The aeC of raisiog the handle buU the nurenC ofl
from the oantrolLer and thus extiniuinhte the Umpe. The awitoh ia
mrr«aKfld for switchboard mouatinff. the dial and handle b^ns on the faea
of the panel. It ma; alio be provided with an imlioator to ahow the
joa parfomed.
Fra. 06. CoDttoUiDC Siritdi, Cover Rtcoovad.
I^BHp IWUcat*r for Oil Clrnlt ttntJtmr. — The indioalor
oonaiitn eesentialiy ol a hollow tube with a lamp aoeket mounted on a
porcelain besa in one end, held in poeitioD by Buiteble dipe. The aocket
am be eajniy removed and ia intended to hold a 5 c.p. oandle-ahaped in^
[• widoh eilflDda into the tuba. Suitable holn a
rided Cor ventiiatioD.
A coloTVd lens ia secured to the front end of the tube. A ipaDial
. , _ any ansle within an arc o( 180°.
C*>tTOl aad XutrBsaflB* Leada. — The coatrol wirea
the operator
a V-ehaped projf
lecKically operated cireui I breaker!
litable toaoner, to the place where the operatiDf Awitcbboanl ia located.
'he uoall alee of the oontrolliag and conducting devicee permits a large
umber to be grouped in a comparatively email space where they ate eaeily
cobble to t£e operator.
The aiiea cl conducton usually required where leugtha do not exceed
OO fnt. ar« as foUowa:
For Hriea tranfonaer oiromtB, each lead eqiiivaleait to No. 7 B. A 8.
For voltage tiwufortner cirouita, each lead equivalent to No. 10 or 13
<a. B. A S. eonduDtor.
For static ground detMtors, each lead equivalent to No. 10 B. A S. son-
eloain^ coil lead equivalent to No.
i
SWITCBHOAltDS.
:>
:>
rio. SS. IS.OOO-Voll. SOO-AiDpcn T. P. UoUr Opentad Oil Bisk
SwiMh aa lUsulkoUmd by (b« Canenl £lasiiia CoapmBj,
CIBCUIT BJ
■V DtneOT CURRENT BY MEANB Or CIHCurT CLoaiNQ R1
I I
Wii
SWITCHBOABDd.
s
LIGHTNING ABRESTEBS.
RbVISBD BT TpWNBBND WoiXX>TT.
IiI«HTlf K1V« PROTKCnOM.
(From BuUetiDB of W. E. A M. Co. and G. E. Ck>.)
Elbctbical apparatUB may receive injuries of two sorts from Iwhtiiiiw.
namely, pounds and short circuits. (1) A ground or connection Det ween
the oirciut and the earth is caused by the potential of the insulated portions
of the apparatus rising abnormally above that of the earth and thetvby
rupturi^ the insulation. But as any properly designed piece of a|>Darmtus
has sufficient insulation strength to witnstand a potential oonsraerably
higher than that normally impressed upon it, a up^htning diachaise to
produce a ground must cause a very considerable rise in the potential of the
circuit. (2) Short circuits are caused by the abruptness of the static
dtsturbanoes produced by lightning. The abruptness of the statie wave
which is the form of disturbance produced in the line by the Ughtning dis-
charge, may strike a coil a blow, so to speak, that under some circumstances
causes a short circuit. Electric apparatus requires, therefore, lightning
protection of two sorts. First, protection against grounds; second, ■g^J'Mit
short circuits. Protection from grounds is secured by means of Ughtning
arresters; protection against short circuits, by choke coils or static inter-
rupters. In very high tension circuits all sudden changes of statie potential,
such as may be produced by switching, accidental grounds, or short cirenits,
cause the same abrupt static disturbances as lightning.
Tli« Function of a lilirktelnir Arrester. — The proper fanction
of a lightning arrester is to prevent, in an insulated cirouit, an abnormal rise
of potential above the earth. This result is best attained by placing one or
more carefully adjusted air gaps between the insulated drowt, commonly
called the "line," and the evtn connection, or ''ground." Exeapt during
times of discharge, these gaps resist any flow or current tunnn^ from the
normal voltage of the line: but, whenever the line potential rises abnor-
mally, they break down, allowing a free discharge of electricity. By care-
ful adjustment of the gaps, an arrester can be made to dischai^e when the
voltage of the line has risen to any predetermined value.
On account of the extreme suddenness of the surges caused in the fine
by lightning discharges and other static disturbances, the gaps and ground
connection must be able to discharge electricity very freely or a dangerous
rise of potential of the line will not be preventea — in other words, the fisht-
ning arrester as a whole must be able to discharge electricity faster tiian
it appeare on the line.
It IS foxmd that there is a very strong tendency, especially with generators
of large output and high voltage, for an arc to form in the tg^ when onee
their resistance is broken down by a lightning disdiarge. Tms are, which
can occur only when one line is grounded, or when two legs of the same
circuit discharge at once, is maintained by the generators, and if not pre-
vented or extinguished will cause a shut-down of the plant. Consequently
the lightning arrester, in addition to preventing an abnormal rise of line
potential, must also suppress any are which tends to form in the arrester
gaps.
AwltcUnr.
On high potential circuits of considerable capacity, an arc produced by
switching, circuit breakers, fuses, or short circuits, causes an electriou
oscillation of extremely high value. Voltages of double normal potential
are often produced when connecting a cirouit of considerable oapadty to
the generating system at no load. These high potentials subjeet the Mpa-
ratus momentarily to enormous strains, and it is well to have some low
breakdown path in which the dsmamic arc will be immediately ruptured,
so that these high potentials will equalise themselves from line to fine with-
out damage to the apparatus.
080
UGHTNING PBOTECTION. 981
In laying out circuitB, it is frequently neoeesary and deeirable to dip
underground when paesing through cities, or tinder rivers, etc., and in these
eases some form oi metal covered cable is generally used. It has been
.noticed from numerous installations that high potentials invariably occur
where these underground cables are used, due to resonance effects, and
these high potentials are often of suflScitot value to break down the cables
themselves, or the insulation of apparatus installed on the Hues. The
strains very often produce pinhole punctures in the insulation of under^
ground cables and thus relieve themselves temporarily j they mav there-
fore remain unnoticed for a number of months until the msulation becomes
verv much impaired, ultimately resulting in a complete breakdown.
Whenever fines contain both inductance and capacity in noticeable
quantities, high volta^^es, which endanger the insulation of the whole
system and which it is impossible to detect on ordinary switchboard instni'
ments, may exist. We tnerefore frequently find such abnormal voltages
in circuits containing a combination of underground and overhead cir-
cuits, and in long-distance transmission lines.
Kngrlne or fVater 11^e«l Chtveiiaor Tr««Uea.
A great many cases have been noted where engines and water wheeli
have raced, caused by the governors becoming inoperative, and high poten-
tials have resulted, which have caused serious breakdowns in insuuition.
This has generally occurred when a considerable load has been switched o£f
from a oircuit.
IHITerencc im Sl«vatton ]i«tw««B Ditfierent Portloaa af
thm Circnlto.
Farticular mention was made at the reomt meeting of the A. I. E. E. at
Niagara Falls, of the abnormal high potential strains which have been
noted on long transmission lines running through mountainous countries
where considerable differenoes of elevation occur between different portions
of the circuits. These differences in potentials are, without a doubt, due
to difference in mafrnitude of the atmospheric electrical potential at differ-
ent altitudes, and m some cases the condenser effects oi the line produce
potentials considerably in excess of the line voltages.
Protection Agrainat AbnonHally Hlg>k Pot«ntl»l« on
A. G. Ctrcnlti.
In planning protection against the disturbances previoush^ mentioned,
it is necessary to provide discharge paths from line to line of the different
phases, and discharge paths from lines to ground with suitable ground
oonnections, except when the circuits are entirely underground, when the
ground oonnections may be omitted.
In view of the fact that it is necessary to take care of considerable quan-
tities of current from Kne to earth when lightning discharges take place, it
is advisable to have an arrester of as large current carrying capacity as
possible, and with this in view, it is often advisable to install a number of
arresters in multiple where the conditions are particularly severe.
Potentials between lines, which are more of a static nature, can gen-
erally be equalised with small flow of current.
In discharging a line to ground, the simplest form of dischMger would be
one single gap, or a series of small gaps with a breakdown point just above
the voltage of the circuit. Although it has been found that a single gap
will discharge a line effectively, the single gap, of course, will not rupture
the dynamic arc when it is once started by a nigh potential discharge.
With a suflioient number of short gaps, it has been found that under
oertain conditions, the dynamic current is ruptured by cooling the arc down
between the numerous conductors; also due to the fact that in some of the
gape the value of the alternating wave is zero, and, thmrefore, after a high
982 LIGHTNING ARRESTERS.
potential diaoharge has passed, the dynamio arc does not start agaiiu Tfaas
arrangement of a large number of small gaps in 8«ies is, however, out of
the question as far as practical use is concerned, as enormously h^h tiraak-
down voltage is necessary to overcome the Jf4>s. resulting in injnrioos
strains on the insulation of the apparatus. ^ Under certain conditions oS
inductance, capacity, etc., a discharger of this construction will not inter-
rupt the dynamic are.
Having selected a length of spark gap as a standard, the point abow
the line voltage at which it is aecided that the arrester shall disduuve
should be decided upon. A definite number of these standard gape wiD m
necessary to prevent the arrester from discharging below this point, and
this number of gi^M will interrupt the d^outmic arc, provided the ourrcnt
is limited to a proper value. With this m view, it is necessary to place a
determinate resistance in series with the gaps, in order to limit the eunrent
to this point.
High potentials between lines or phases occur much more frequently than
is the case with lightning, and it is advisable to increase the non-induciiw
resistance in series with the jgaps to a considerable extent, as this renders
the possibility of short circmts less liable and, as stated above, Uiese hi^
potentials between phases can be equalised through high resistances as well
as through low resistances. A further reason tor placing a oonsidenJ>le
amount of resistance in series with the gape when placed between tines is that
in case of discharge from phase to phase, if the resistances are low, the
circuit breakers or other automatic devices on the line open, finMiting a
temporary shut-down, and this, of course, is inadvisable as well as anno3ru«.
Use of HeiictlT« Colla.
Although considerable doubt has existed as to the adviaabiHtv of in-
stalling reactive coils in connection with lightning discharges. It is Mieved
by many prominent engineers that reactive coils are of considerable vahie,
in connection with the proper protection of apparatus.
Without a doubt, the frequency of lightning disturbances varies greatly
in different cases, although, as a whole, it is probably high. Inasmuch
as the action of the reactive coils is not dependent on the voltage or fre-
auency of the line, it is inadvisable to design a large number of oous having
ifferent reactances, and it is evident that a coil can be designed with ample
current carrying capacity, which may be used on a number of voltages,
firovided it has sufficient insulation for the highest voltage determined upon,
n this connection, air insulation is to be inferred between turns and laym
as other forms, due to minute discharges, gradually deteriorate and change,
becoming partial conductors.
lJa« of a Protoctlvo IViro.
Protective wires have been used in a great many cases by different iraas-
miasion companies with varying success, although the experience gained,
as a whole, has been in favor of this form of protection. A neat many of tlw
troubles encountered through the use of this wire have oeen due to the
selection of improper materials in making the insulation. Barbed wire has
been used in a great many cases, and the commercial barbed wire purchased
in the open market is of very |)oor quality and has a tendency to hold water
in the joints and interstices.
In one place, in particular, different forms of protective wire have been
used, placed in various positions with regard to the drouit wires, and it
has been fotmd that plain iron wire installs directly below the transmission
wires, furnishes practically as good protection as barbed wire instsdled over
the transmission.
As a matter of fact, there are few reasons why this should not be the case,
provided the iron wire is properly grounded at every third or fourth pole^
as the disturbances which this form of protection is supposed to take cars
of are generally at considerable distances from the transmission wires.
While this form of protection may help out in the case of a direct stroke
of lightning, it is not to be presumed that it will prove entirely efficient under
this condition of affairs.
LIGHTNING ARRESTERS. 983
While the eamerience of the above mentioued plant has been that a wire
placed below the transmission is as satisfactory as if placed in any other
poaition, it is as well to string it above the transmission lines at aa ancle of
approximately 45^ to the outside transmission wires, as this locality wul aid
in taking care of direct strokes of lightning.
With the improred lightning protective devices on the market, the
grounded protective wire need only be resorted to where the most severe
conditions exist, and then it should be put up in the most thorough manner
with regard to the sise and quality of the mat«ial used and with regard to
grounds.
In the installation of lightning arresters it is very imdesirable to endeavor
to effect a saving by cutting down the expenses connected with making
proi>er ground connections, as fully 75% of lightning arrester troubles can
be traced directly to this source.
The connections from the line to the arrester and from the arrester to the
ground should be as free from angles and bmds as possible, and where turns
are absolutely necessary, the wire should never be bent at an aiigle. but in a
curve of long radius. Care should be taken that no inductive loops are
formed by the complete arrester and its connections.
When the use of an iron pipe at the foot of a pole is considered advisable
for the protection of the ground wire, a plug should be put in the top of
the iron pipe and the wire soldered to it; otherwise the reactance of the
ground wire surrounded by the iron pipe will impede the discharge.
Copper sheets should be used for the ground, thick enough to prevent
wastmg away and having at least 4 square feet surface. The gpx)und wire,
which should not be less than | inch diameter in cross section, and prefer-
ably in flexible strip form, must be carefully soldered and riveted to this
plate, the joint covered with asphaltum, and the plate then buried in
powdered coke in soil which is always damp.
Dry, sandy soil should be kept wet by artificial means if this is the only
soil available for the ground connection, and it is advisable to dig several
trenches radiating out 50 feet from the main ground wire, in which ground
wires are buried, so as to get a large surface for the dissipation of the dis-
charges. Where plates are buried in streams of running wa^ or dead
water, they should be buried in the mud ak>ng the bank in preference to
merely laying them in the streams, and streams with rockv bottoms are
to be avoided tmless as a last resort. Where there are metal flumes, pipes or
rails, it is advisable to rivet and solder the ground wires to them in addition
to the connections to the copper plates, and when rails are utilised they should
be thoroughly grounded.
Xiiglitiitiic Arresters.
Practically all plants with outdoor circuits require Ughtnixig protection.
With reference to the type of lightning protection required, electric plants
may be divided into two general classiBS — those plants in which the ap-
paratus is widely distributed, and those in which the apparatus is concen-
trated at a comparatively few points.
JPlanta lI»vlB«r Api^ratiia Dlatrlbated. — To obtain abso-
lute protection, arresters must be placed at all points where apparat\i8 is
located, but experience has shown that in certain cases such a large number
of arresters is unnecessary.
In circuits not exceeding 2500 volts, it will usually be sufficient to place
arresters at various intervals where good grounds are available. These
arresters should be so placed as to leave no considerable length of circuit
(electrically speaking) unprotected, and should be more numerous in neigh-
borhoods where the circuits are exposed. These are more likely to be the
outlying districts where the lines are not protected by buildings and trees.
The exact number to be used in any given case depends upon circumstances.
Under average conditions satisfactory protection wiU be secured if no point
of the circuit be more than 1000 feet from an arrester.
For voltages exceeding 2500 volts, arresters should be placed as nearly as
possible at or near apparatus on exposed lines. However, circuits of this
type with voltages ezoJaeding 2500 are rare.
984 UOHTNING ARBESTEBS.
Points. -~- In plants of this ehus, whioh comprise praotioally all high ten-
sion work, one arreeter should be used for each Ime wire, at or near each point
at which apparatus is connected to the drouit.
In all esses of circuits with ungroimded neutrals, arresters rated at the
voltages between line wires ahouki be chosen; that is, Cor the maximnsi
working voltage and not for the voltage between line and ground. This
method insures that the arrester will be non-ardng when one leg of the
euit is aoddentally grounded.
If the circuit has a Orotmded Neuiralt arresters, to secure ample mai
for i>roteotion. should be chosen for a yoltage 20 per cent greater than tl
liaTimiiTn voltage between Hne and ground. For example, for a circuit
with grounded neutral having 16,600 volts between line and ground Cap-
proximatehr 28,000 volts between Knes) arresteri for 20,000 volts shoukl be
chosen. If. however, the transformers are connected in star in both high
tension and low tension windings, arresters should be chosen as though
the neutral were not grounded.
The arrester should always be placed on the line ride of all appanftua.
The arrester (if of low equivalent alternating current type) is choeen solely
with reference to the voUa0§ of the line upon which it ii placed, and is inde-
pendent of current.
JInaalatlon. —A Ughtninf^ arrester is naturally exposed to severepotential
strains, and therefore all active parts must be well insulated. To obtain
sufficient insulation on circuits exceeding 6000 volts, the panels should be
mounted on shellacked wooden supports, well seasoned and very dry. On
arresters exceeding 12,500 volts, the paneb should receive additional
insulation in the form of porcelain or glass insulators. It should be assumed
in installiiu: an arrester that all parts of the resistance except the ground
terminal ot the series resistance may be momentarily at linepotential auring
the discharge. Two hiah tension arresters attached to different line wires
should not be placed side by side without either a barrier or a considerable
insulation space between them. The resistance, which during the dis-
charge mav reach full line |>otential, must be soaoed or insulated (except the
ground eikd of the series resistance) as well as tne line.
IiMvectlon. — As the effectiveness of the arrester is of great importance
it should be inspected from time to time and the reeistances and earth
oonnection*te8tea for open circuit.
Clioke colls should be so mounted as to have free access of air for cooling
purposes, and should be so spaced from one another and removed from other
objects that sufficient insulation space will be obtained for the moet severe
conditions, vis.: during lightning discharges.
A non-arcing D. C. arrester has been devised by Mr. A. J. Wurts based
upon the following facts: —
Fir^ A discharge will pass over a non-conducting surface, such as glass
or wood, more readily than through an equal air-gap.
Second. The discharge will take place still more readily if a pencil or
carbon mark be drawn over the non-conducting surface.
Third. In ordw to maintain a dynamo arc, iumes or VMors of the elee*
trodes must be present; consequently, if means are provided to prevent the
formation of these vapors there will be no arc.
Tlio Typo *'K^' Arreator. — The illustratk>n, Fiff. 1, shows the
type "K" arrester for station use on D. C. circuits up to 700 volts. Ths
instrument is single pole, and consists of two metal electrodes mounted
upon a lignum-vite block, flush with its surface. Charred or carbonised
grooves provide a ready path for the discharge. A second lignum-vito
block fits closely upon the first block, completely covering the grooves and
electrodes. Disruptive discharges will pass readily between the electrodes
over the charred grooves, whicn act simply as an electrical eraek through
the air, providing an easy path.
The resistance between the electrodes is more than 60,000 ohms, so that
there is, of course, no current leakage, but it should not be understood that
the lightning discharge passes through this high resistance — it lei^s over
ASREBTEBS FOB DUtECT CURB£NT. 985
® wna ®
EM^
• "
"
»
') ^
n
•
0
•
s
<9
1
^
•
(S
Fid. 1. Mon-ArelDS lUihray Lightolac AiT«n«r, Tyfw "K.
Lightolnc
thtl aurfsM of ths ohBirvd sroorsa Iroi
one •lartiwla to the
I tichtly GtliDs bkwka, no
i luchCnliuc anvflter ba*ed
lUiia by B macnetia field.
i
koroas whluli th« lichtDiDg dbcharrca to nac
1 fiakl of ft strong electro-munet. Whan iL
to follow th* high potcDtisT dbchvcs, it
iQ on the divwcioc oiwtoeM wh«« it ouuiot t
r
986 LIGHTNING ABRESTEBS.
The munMia blow-out principle bmM beeti employBd in th*
of K oompTets line ol lisbtniug sirasten for >U direr' '
ftruk itt more tbui ten yean of Bervioe mBgnetia b
mlmyi l»eii effective in ■flaniing proterrtion to elBotcickl kpparatu*
la deei^ning Lifhtnins >TTeater9 for the protection of lush-TDlt«
Dating current circuilB. ncwerer* different eonditicne have to be m
Ugb-voltage mm »« not re«iiiy ■itingulslwl by r ■"•"■■*«. hin^-
• recently deeisned liclitning vnater for kit*
metallic eyUndera withlarKe mdimting (urfaoes ni „
tempantim of the arc tlut rolatiliiation of the met«] Masea and the an ■
•itincuiabad.
The variety of these lightuing aireaten provides for the pnteetion of al
fonna of electrical appanttiu and circuiie.
The Type "A" Arreeter is manufactured tor the protectian of ve Kghtinf
drcuits. Id cooilmctioa inciudea a pair of divernng terminsla moonud
on a elate base with an eleiitrD-nu«net connected m seriea with the Em
The magnet windioBB are of low reaigtanoe, and therefore ooasuine an i>-
appreciable amount of energy with the nnAll ouirent uaed for arc iia>»tiii^,
although Ihey are aJwayi in circuit.
The liiiBle Type "a"' Anwter ii luiUbte for eirouite o( any Quobv ol
a double aireets' known as the type "AA" ie made by mounting two
arreateri on one iuse and ounnecting them in seriei. One arreater ebould
be ingtalled on each side of the dniiiit, aa shown Id the Diagiom of Coa-
For use in places oipoeed to weather, the Type "A" Arreeter la
eodoaed in an iron case, and designated Type "A," Form "C."
Fia. S. Connections for Tyiie Fis. 4. Type "L
"A" Arreelers. Station Arreater 300 Volt. u. .«
The eanslructian ol the Typo "B" ArrBetHr is similar to thai of the Type
"A." but lis magnst windings are eitcited only when a discharge lakes place
across the air-eap- A aupplementvy pap is provided in the Type "B"
Arrester, in shunt with the magnem. Ibus providing a relief for the eoUs
from eicesHlve sialic charge withuut frffectiog their action upon the main
gap. The magnet hiiIh, carrying current only momentarily, allow the lanie
arrester U) be used on circuits <if larice and small ampere capacity. The
Type "B" cKi, also be furnisbKi with westberpruof <ase slcnilar to thai
used with Type "A."
The Type ''MD" Ughtning Arrester has been dnigned briM on djieet
current ei.cuits up tofcO volts. While similar to Type "M," Form "C
UGHLTNING ARRESTERS FOR ALTERNATING CURRENT. 987
Tl&e srreBter has b«en adopted as standard for railway and all direct
earrent 500-volt drouits. It nas a short spark gap, a magnetio blow-out
and & non-induotive resistance.
co*<NECTioNe or
MAGNETIC BLOW-OUT LIGHTNING ARRESTeRS TYPE MD.
FOR DIRECT CURRENT CIROUrrS OP TO SBO VOLTS.
COWIlBTIOia PM LMKPWO OH TOwn
(WTALio omosrre)
«MMTM STATION* AMmTEm
CAN AMD tS« AMM
FOR RAILWAY
nrr.oit ooHOwmM woono «
MIL or TWO 9m wow
M ooNvcNicirr.
Fio. 6. CSonnaotionfl of liasnetio Blow-out Lightning Arresters,
Type "MD." for DirectCurrent Circuits up to 860 Volts.
The G. E. Alternating Current Arresters have been designed to operate
properly with very smaUgi^) 8pa<»8. The arrester for 1000-voIt circuits has
two metal cylinders 2 inches in diameter and 2 inches long, separated by a
spark gap of about Jk inch. One cylinder is connected to tne overhead
hne and the other cylinder to the ground, and a low non-inductive graphite
resistance is placed in circuit. The large radiating surface of the metal
cyUnders combined with the effect of the non-inductive resistance prevents
heating at the time the lightning discharge passes across the gap, and the
formation of vapor which enables the current to maintain an arc is thus
avoided.
The arrester under normal action shows a small arc about as large as a
pin-head between the cylinders.
The arrester for 2000-voIt circuits is designed with two gaps of approxi-
mately A inch each and a low non-inductive resistance.
The G. E!. Arresters are now furnished by the General EHectric Company
lor use on all alternating current circuits at practically any potential. For
oireoits above 2000 volts, the standard 2000-volt doublenpole arrester has
been adopted as a unit, and several of these are connected in series to give
the necessary number of spark gaps.
r
988 LIGHTNINQ ARRESTERS.
t*mA.A -i^
Fio. 0. G. E. AltenmCioK Curmt
Three-Phue flukiplei Ugbtoiag
LJQHTNINQ ARR£ST£RB FOK ALTBBNATINa CURRBNT. !
Fia. 10. Diasnm Bhowlng Heotrio] Coanectiaiu lor A. C. LightnlDs
Fin. 11. ODabl»-Pt
i
-Aroiu Metal Ughtnius AuvbUt, TypB "A."
n the I
f mode by Mr. J
when Ibe etectrodee doi
mnd "C" ureflters, dee
Tbe xrpe " A" Ai-rrtsHir ine ooai
be best imdentood by reference to Fig. 11.
It iritl b« DoteJ that there sre »eveD iaJepei
metal pboed ekle by aide sjid separated by oir-sapB. 1
are mounted on a marble base, are knurled, thiu preeiiui.uia uuuuisu> m
coarrnnliiu points for the diKharie. The dynamo terminals are eoDDeeted
tu the eDcT cylinders, and the middle cylinder is ooDnected to the ktouikI.
The arrester ix. thmlore. double pole, that is, one arreela- pmtectg both
■id» of the dniuit. Wben the bnes beoome —--"-■ ->- ■ -■-- J'-
oharse epark pus« acroaa betweeo the cyLinde
the ground. The non-ardi " " "
TKioui areins and ihort d
y eha^ed the dia-
r
990
LIGHTNINQ ARRESTERS.
Tli« Vjp« «< G '* Arrmifer. — This is similar to type " A." but iniTfil
of being mounted on marble it is enclosed in a weather-proof iron, case fiar
line use. The cylinders are placed in porcelain holders, as shown in Fig. 12.
M
Fig. 12. Unit Lightninc Arrestert Type*'C," Showing Cylinden in Pboft.
Tbe C^arton Aii—ter.— In Fig. 13 a<
section view is shown of the Garton Arrester.
The discharge enters the Arrester by the Idnd-
!ng post A, thence across non-inductiye resistaaee
B, which Is in multiple with the eoll F, thiv>Q^
conductors imbedded in the base of the Arresfter,
to flexible cord G, to guide rod D and armature
Ef which is normally In contact with and reet-
ing upon carbon H. thenoe across the air-oap to
lower carbon J, which is held in positfon bT
bracket K. This bracket also forms the gromra
connection through which the disoharge reaches
the earth.
We have noted that the discharge took its
path through the non-inductiTe rwlstanee in
multiple with the coil. This path b, howerer,
of high ohmio resistance, and the normal car>
rent Is shunted through the coll F, which is
thereby energized, drawing the Iron armaturo
E upward instantly. This forms an are between
the lower end of the armature and the upper
carbon H. As this arc is formed inside the
tube O, which Is practically air-tight, Uie oxygen
is consumed, the current ceases, and the coll
loses its power, allowing the armature to drop
of its own weight to Its normal position on
the upper carbon. The arrester is again ready for another discharge.
mi« A. K. C. l«lrli«BilBr Arr««tf)r Bo«lpni«B«, manufactured by
the Stanley Electric Mfg. Company of Pittsfleld, Mass., consists of three
essential parts. The Lightning Arrester proper is two nests of conoentrie
cylinders, with divergingends held in relative position by porcelain caps, as
shown in cross section. Fig. 14. To the innermost cylinder the line is con-
nected ; to the outer, the earth. The porcelain oaps are proTided with
Fio. 13.
THE QAKTON ARRESTEE. 991
pooTsa >o placed u to make nil ipnrk gan oas-iiIt«inth in<ib wide. Be-
.-we«n tlieee groovoa arc euQIeleDt perf oratfona to allow the free clrcnlatioD
it air betKeen the CTlinden. If, on the occasion oF UghtnlDK, the dTnaino
jorrent follova the llghtnlns. a current of sir Is at once catablTshed through
lUe perforatiODB betwsan the CTllnders, blowliig the arc between the flar-
Ing ends where It Is Inatantly ruptnreil.
Between the line tsrmlDal and the groond connection there are three
■park gape, each onfreliteenth Inch In width, ■"■'■'"g a total ot Chre»<Ei-
Via. M. Pio. IG,
teenth inch air-gap between either llne-vlre and the ground. At ordinary
arrester^ but at the frequency ef a lightning discharge theeparklug poten-
tial is reduced to lees than one-haU of tbla. Thll phenoiaenon ebuve that
■■ long," and their effectlTanees ai lightning protection cantiot be meaanred
Vhe ipark gaps of the arrester described are about double the widths
ordinanly used, yet the sparking potential at llghtnLng frequenclee is less.
Tha concentric cylinders prov^e large discbarse sarface, enabling the
arreecar to take care of all the heavj discharges, rellerlng the line cumpletelT.
Tbe second essential feature of the B. K. C. Lightning Arrester Eqidpnient
[fl a Choke Coll, m> wound (Fig. IC) ss to possess great opposition to the
ke Coll, M> wound (Fig. IC) ss to possess great opposition to i
if lightning, yet practically no self-lnduotlon wllhourrenta of or
luency. This ooll is (o be placed In
'"--■----,B the lightning arrester and
be protected. Introducing
the elre^t
the appara
and the maehlne will oilfer praeticaTiy no dls-
torblug effect, either as to magnitude of the
ontpat or regalatlon of theiystem. and at the
same time int^rpceaB enormous opposition to
the passage of lightning discharges towards
tha machine to be protected.
To remoToeien th s slightest Btattediaebsrae
frn-. the line, in In.trnmnnt similar to the
^Alled a -'Line
le appa
ir
tabee,
: practically an Indnlte resistance to dynan
Line DlacliargBr Is connected Co tlie line u shown In Fig. i;
DIscbargBr." when
plately. The S.'k,
niled with oiidlied
B Discharger is i
i
of bib« nquind ia delcmiined by thevidtBca. Ai the ',
nmov« even tba snull Btatio elatgt, it pravtota the w
ohargBB on the line which mi^t prove dutgeroiiB-
oaeotloru are vb- ,
d odjiuud to break iotra et lUfht b
if Stktle Diediaisvs.
^ ^ . _._ , .. Eiequently pAaaes with diffloulty tbrou^
oils of win. Moieova, the freauency ol ogcUlatioa ol a lichtnios dis-
ib&rce beina much BrMtB- than that of commeccial aiCernatlna «i ~
oil cfw Totaily ■- ._...._... .
ARRESTERS FOR HIQH POTENTUli CIRCVIT8.
(AbMrset at pM>Br by Percy S. Thoiaat ia FranUia IniL Jaun.)
A. liahtninc discharge ii of an □sdllHtory
iiS?
lly ba ooiutructni which will offer a relatively hish
HI iius tiiuu^ of UBhtoins and at tiie w — •'■ " — '
onlinory eleotrii: aurra&ta.
A more oomplete metiiod. a metliod of
whlcli i« available lor Usher voltacn, if
which is lubstaotiatly a macni'ied chokt
the «t-' ■- -■ '-- "- '
full poteatiall
the traDsformer, wt
Uia instant* of liuie' » that the'
coil will be. oompamtLvely speak-
ins, sruiusily brought 1<j full pc^
the ata..-
mod clioked bftok n
diacharzed b ^'
b« > licbtnii.
la evident that this choke a
be atlMtivek must be ao pt-^:..
tioned M to delay Uie incomina Flo. IB. Slalio IntBmipter Proteoling
WftVO CDOUffh BO that the portion 'j'»....tf^»»^ *
of tike windiOE which has become
shanced whan full potential is reached at (he tenrnnsl shall be suiSdeDt to
iHthstand the strain of the lull valtsge of the wave. It is evident that such
adjustmeDt dose not depend directW on the frequaioy or abruptness of the
HtMlo wave, since both the tiuulornier and the ijuika ooil are similaily
aitected by the frBqueiicy.
But a choke coil eufEnenI
of the siu, o
I a choke coil eufEoiently powerful to accomplish this result satisfi
IS found to be imprMtioabieon very high potwtial cinniitson accou
aver, if (he anaogement of the static interrupter I
d ground behhid the choke odU
,B, tected, this S^ltTcoU will ab£^
a considemble portion of the aa-
rent actually pawed by the choke
li. coll. and the time required to pan
BuffirJent electi^ity Ki charge the
*na. twminal will be much increased.
With this BiranoemeDt a compera-
„ lively small choke coil may be
,,„„^^,^ If oeod. The condenner has ■ very
-JO. Statio Infarmpter Proteot- email elcctro-gtatic cawcity, and
ing Hlgh-len»lon QensBtor. ™" "? appreciable eftect upon
_ normal operslinn, and yet has a
._^ powerfui effect an the statis wave on account uf its extremely bigh
trequenoy. As in the case of the choke coll. the siKtlc Interiupter must be
Li.. .: 1 ,_ j^g transformer wlndine to be protected. Th«
— . citable for the voltage between line BJid ground.
miptera be placed in each Ipftd nf high tension apparatus
njuied by local ronoentmtion nf potential, its windings wiB
., tted against danger of short drruite from static wave either
nr ne«alive. Such an orrangement is shown diagmmmaticariy In
Ion witb a transformer and a high teoiioii geiieratar in Fi^s. 3 and 4.
roughly proportioned b
i
994 UOHTNINQ ARRESTERS.
8«MIC ■■**■
I.e. Ll^IilBlai: Arr«t*r eoa^sUoIi
numoer ?' A iacb air gapg betwem dod-aibdc
tftnoe. A porlion of the miatsnDe. cajlcd ihiuit
nautancA, la Bhuat«d by a Becond «ec of ^ir [■[«
sailed ahuuted giam. llu object ot thin mtnarf-
ment ia to reduce the ainount of the serin n»-
taooethroush which the diacbarge must mm to
iSted in Fig. ST"'" " '■■™™"' ™^ """"^
The aeriea gap* withhold the line voltaee aod
are chosea so as to hiflc down M SDmethiis
between SO per ct^t and 100 per cent liaT^
voltage above thai of the earth. A mrtior -*
U„ : :- :. .u...._i ....
>
5
0 o o-L-o o o o o o o o-kyWHl"
FiO. 23. IKaeTBm of Low Equivalent tlgbtnins Arrstor.
In place of alf. Thla has the double efTeet of Increaalng its eleotrprt^ie
(»pacily and chanciim the Telocity at which w»v« proneaa. The in-
owwd electroatatic capacity teait to dtwcaae the apeed, but as (he
inductance of the cable ia amall this partially eocopenaatea lot the m-
ereased capacity. The differences tram the air fine are diffennoeB In defie*
only, and do not affect the paMa«e of wsvee, re6ection, reeonanee. e«t
Conaeqiwntly, no phenomena different from the air hoes may he expeel^
aa a result of atatic dieturbaocee.
fflnee the cable contains no colli of wire, no local ooncenlrmtion of potm-
tiai wilt be (ounil bite that in transtonner coils, and there ia no oecunn foe
the lue of a alatio interrupter.
ABKESTEBS FOB HIQH POTENTIAI, CIRCUITS.
In anienl mr ic mut b« uraacMd that tba mrgliw about of the i
vhieh u Noni wUMurar a line la ohariad will au» fiiwi il pot"
lertain pointa. This ahaiild b* prevklM for br phudDS sultabM 1
'XSS
ths oirouiu »a the racuH ot all itaUc duturbuuKK Suoh ti . .. _
other eoik abould almya ba dthec «uffid«ally innihitwl or piotactcd br
lOtokB colli or BUtio iDtWTupten or by Bine ather aulubia mnhod.
^•imTn>*- — This MTMUr wu Invstted by OriwhlMgaf (or the AU-
-mfiiie ElMtridtaeti OaHUoihalt, ud like the Thamaon MCM>ir«iit
reotar, Ita openUou ia baasd on the fut that ■ Bhort dreuit onoa itartad
«v the beae, the haet of the are will cauae it lo travel upward until it nq>'
turea by attenuat^n* On ^ciuta of high voltage Ihia nipture- aometlmea
takea a aeoond or two, but aaema (o aot with but Uttls digturbanoe at the
liiiB. It haa bean uaed little in tbla asantry until lately when it baa been
lactaDed on a tsw ot the hich voltase linea on the Pamfio eoait, and the
reaulta are an tit highly oomraeodable.
The IbUowinc firirea. Nob. 23 and 24. ahow the ^ipUcatioo, one aa applied
to tbe line, andthe other in diacratn.
The bnee-ah^ied harm are of No. 0000 eopper wire, one oonneoted directly
to the hna, the other throUBh a WBt<r reditance and cluke coil lo the aniund.
The borna an mounted on the re^olar Ena Inaolatora. and lor WjOOO Tolta
reoeptaole ihould have a caiiadty of at least If
_i — 11 — .1 . 1 u 1— J ,j|. added. .
gut one-eiohth inch deep ia order to prevent
•an be made of atxiut eichteea tuma of iron
, , J n ISnUona,
wheths the waMr ahoukl have aalt added. Tbe water diould, however.
be eoveied by a layer of oil al '
i
996
LIGHTNING ARRESTERS.
Care abould be taken that the knee ia not too sharp, or the are ia liable to
reform alter being once broken: a^n, the home shoukl not lie too flat, or
the arc will strike.down as shown in Fig. 24. The curve of the knee is aoi
alike for all parta of the line, but depends on the line count: ante, and will
have to be fitted to each case.
OM-CWNTN mCM
or OIL
"tfc MOTION or X
TO MAIN LINI
*hvr-r \^
• IMCNCS
. OOPMU STIIir
ONI INCH WIOC
0 TOOSMACL
ARONOCMON
KNCt
TOOIMANT
ARC rrmicco
•ACK
mOUNDCO ON
riMUNB
Fio. 24. Arramrainent of the Parts of a Horn Tvpe lichtnioe
Arresto*, the Two Small Diagrams to the Right Showing Faulty
Conatruotion of the Horns. — N. A. Eckert*
BLBCTBIGIT7 MBTER8.
Reyisbd bt H, W. Youko.
IbTBRS for meMurins the amount of eleotrioal energy f umiflhed to oon-
•omen are known as recording or integrating watt^our meters and are
made in several different forms to meet the varying oondidons. The regis-
tration of an intejsrating meter must be very accurate to meet commercial
requirements owing to the fact that any errors which may be present are
oomulative and even a small percentage error will, after a lanse of time,
become relatively important from a pecuniary standpoint. The accuracy
must be especially high at the lower end of the curve owing to the fact that
for the larger part of the time the actual load is but a small percentage of
the meter's capacity, and a meter which shows inaccuracy at this point
eannot be a profitable investment for the central station for the reason that
the tendency is to under register rather than over renter.
JLmUmm of Mmtm^prmma^ Hetora. — The action and operation of an
integreting meter may be likened to that of a smaU direct-connected motor
senwator set in which the current and potential coils are considered as the
motor element and the disk and the permanent magnets as a magneto-
genemtor with a short-cirouited disk armature. The work expended by the
motor is absorbed in driving the short-circuited generator and overcoming
friction in the bearings and registering mechanism. In a perfect meter (or
motor generator) all the work woula be expended in dnving the disk or
generator — friction being absent — in which case a direct ratio would
exist between the speed and the energy passing through the motor ssrstem,
thus giving a meter absolutely accurate throughout its entire range.
It 18, however, impossible to entirely eliminate friction, but it will be seen
that the more perfect the meter is, the greater will be the ratio between the
work expended usefully in driving the disk or armature of the generator
and that expended in overcoming motion; or, in other words, the Ratio of
Torque to Friction" in the meter will be high. Meter manufacturers,
recognising this essential feature, endeavor to make this ratio of torque to
friouon verv high by efficient design of the measuring elements and reduc-
tion of friction m the bearings and registering mechanism.
The best known of the direct-current meters is the commutator type con-
sisting of a small motor driving a registering mechanism. There are ususlly
two series coils wound with comparatively tew turns of heavy wire and prac-
tically surrounding a pivoted armature containing several coils of fine wire
suitably connected to a conmiutator on which bear small brushes. In
series with the armature is a comparatively hi^ resistance and a light load
or friction compensating coil. The stationary series coils are connected in
series with the load and the shunt cireuit consisting of the armature and its
resistance is connected across the line.
The construction employed gives a driving torque proportional to the
energy flowing in the cireuit. and to secure correct registration it is necessary
for a retarding torque to be provided which will be proportional to the
driving torque. A controlling force varying directly with the speed is
obtained by causing an aluminum or cop];)er disk to pass between the poles
of permanent magnets whose fields induce "Foucault" or eddy currents in
the disk. The interaction between the fields of these eddy currents and the
field ci the permanent magnets produces a retarding torque varsang direcUy
with the disk speed. With such an arrangement of dnvini^ and retarding
torques a rotation is produced which is alway; proportional in speed to the
driving toraue and, therefore, to the energy passing through the measuring
ooils. As the measuring elements do not employ iron and are practically
non-induotiveb the meters can be used on either A. C. or D. C. eireuita.
997
{
ELECTRICITY METERS.
nand E[«l
>
TbM DMlan (Ft(. 1) iin of (be eommuUtor tri» pnvlouBlr dsBribnL
Ukd lh« t^iBDt foitund d&imed arc a« foJlom: Hisb toit^ufl, dinct-nKdini
NgiaMn. diut proof ooiutnHtioa, noaU ■!■• oonunutBlor. cravity biusho,
kdiuat&blashunt Gold ooil. inur-
ohBOcMbla on D. C. «od A C..
Cftpfcit]'. imii bnnnsa.
■ [ arlliai — The top baar-
idiu bavins a bole tjt ~
liM U> allow fna lotet
umatun ihaft.
The lower bsari^ eoOBBto <f
• hsrdaned slaal pivot nuda d
piapo wlra and nalinc on ■
■piini aupportad tkppfaiia or
■fiBiDOad 3*wd. Thn manna
a bcarins hannc a lowftietkn
value and lonf life. Duriat
ahipment Iha ;e«ila ttra pio-
Fio. 1. Tlom*™ RMnrdini Wattmater ^ °L"m^^ ^^
(Cover Ramoved). highly poUabed atoal ball m-
tng between two wpphiie )■*■
•la, one of which ii aecured in a rsmnvable Jewal screw. The idea of thia
foim. of beacinc ii to pmeni constantly ohnnging contact! between the baO
!llief^ jewel ll°e and fnor^td ^urac?* '"Burint^Bbipm^Pl^diskw
looked |in poaition by a suitable locklni device operated tioin the Uig
Thii metn- (Fit:. B) in canunon with Ihe Thonuon and Weatlnshonaa
forms, ffl of (he commutator type and practically the aame daima are made
m* for the other fomu.
It diflara in the method In the friction
the auxiliary Rtld coil ia provided with
awilch. Tina ■rraniPment enablea the auniiiery lorqu
TheHower bearing is of the "i-iaual" t^pe deai«ned U
VE3TI1TGU0USE D. C. INTEQBATIlia WATTMETEB.
FrlMiv'* 'f OparitlliMi, — The nngle-phue lndnctloD mttmsterli
• Btsttoiwry ^DDt lud serica winding to rdsted iLnd loonMd u to produn ■
the iwooiiiUry oongista ^ a 1i(bt aJumiiium diik. The ehaat wiBding, con*
«i.ifiD^ of a Larse Dumber of cunu of fine wire wound on a Lamina(«d iron
ooT«. JB hii^v inductive &ad i(e oottvpC Ibeh approilautelr 00 dearer
behind the impreeied oi luie voltase, The leries windius ooosieliiig of but
i
« D. C. Inle«rating WatI
eriiv masnetio fieJd will be in phase with the impreeaed or Jine volte^.
'htu the magnetie field produced by the shunt winding will lA^ approxl-
aalely 90 decrea behind thai of the eerin windini on ■ non-induelire
ud.
With thii relation ol the two Gelds at the instant of time when the curm
n the eeriee soil ia grealal the ourrenl in Ihe nhnnt ooil is the leaet. Of
■ TOuld be exactly »0 it^reei.' " '^ ■ •
KlteniatioD of theelnult the series ooil helps the Sux of one pole of iheshui
baa tha oppoMta •ffeot; theea naotions beini oombined in lueh a way u
SLMCTKlCtTX HKTKSS.
i] ihif tine ol Cfae linea of tone in oh dinctimi — tlut is.
Atcinff a rviatinojieit—
Ba«stlH PlaM.— That the shiu
rDbttiai field m '
n^CioD of Uhbb two iHtoa lor
the WHS.
RcfvTinx to Fic^ 4 and Doling
an dcnnuted by ttu Ictton A — A, and C. and i
maanat br B~b. a dear ilstsasnl o( the rBlali..
quarlflT periodi ifl ^veo in the table shown in Fie. ^-
nwriVM BTOi ID thii table rcpneent the imtanti
induoe Foucaull " ™ .
betweoa the fidda of th^te taay
^a«nete prodacre a retardiDE lorotw
therefore to the enersy paesinf
ly BO deer«a behind the line voltaiie and
. _. .__n "(he loiui i« non-iadiietivt (such ae offered by incut-
deaeent lampa) the ourrent of (he eerin »!! will be in phue tritb the line
voltnce and the ahum and eeriH fieldi will differ in phaae by exsclly tW
decreaa. Fram the table (Fii. 5) It will be aeen that this ciTea a mailmiim
pulTon the disk.
eumtnt ia Ihe'aeriea ooii willlag 90 degreea behind the line voitasa mod wtU
be in phaw with the current in the ahunt mil. Under theae wnditioiH th«
■Nation between the flelda for »ch one-quart«r period of a complete eyd*
INTSaRATING WATTMBT8R8.
1001
FiQ. 4.
A
+
KP«W 0
Si Period ^
•^PWod 0
PuO Parted
I
B
0
1 i
:*» :« ^ K
Fio. 5. Table Qiving Relation of Fields by One-quarter Periods.
r
1002
BLBCTRICITT MBTEB8.
At start . .
At i period .
At I period .
At I period .
At full period
When A' b
B'u
Cis
Dia
.4. is
+
+
+
0
0
0
0
0
—
—
+
+
—
0
0
0
0
0
+
+
^^
"^
+
As no progression or shifting of the field oeoura, there is no rotation of the
disk and thus the meter will not record when the current in both the somi
and shunt coils is 90 degrees out of phase with the impressed voltage; henet;
the meter will record true power whelher the load be inauetive or non-indutiiee*
P«w^er Factor C«Bip«Ba«ttaB. In the preceding diagrams it was
demonstrated that foroorrect registration on any power factor, exactly 90 per
cent phase relation between the shunt and series fidds must be obtained.
Consequently, compensation must be made for the small decrease of tfaii
anjde caused oy the copper and iron looses in the shunt circuit.
Tliis compensation is usually obtained by placins one or more short cir-
cuited turns (or secondary) of conducting material around the projeetiBC
pole C of the shunt electromagnet, producing an induced magnetic Ma
which, acting with the shunt magnetic field, produces a resultant field
lagging behind the field of the series coil. By varying the poeition or rcsia^
ance of this short-circuited turn (or secondary) the compensation neceasaiT
to obtain the exact 90 degrees phase relation may be obtained. This method
of securing the resultant field can be better under-
stood by referring to Fig. 6 in which:
OA represents the voltage oi shunt coils.
OY represents current passing through ehuat
coils.
YOA represents angle less than 90 degreee doe
to iron and cop|>er losses in shunt coils.
OS represents induced volta^ of short-circuited
turn K and exactly opposite m phase reJatioD to
that of OA, but very small in value; the current
passing throui^ the short-circuited turn K being
m phase equal and approximate to OC.
This current OC and main current OY have
Fia. 6. Diagram of R^ a combined magnetising effect on the iron core,
sultant Field. which effect is found by forming the parallelo-
gram OC — X Y when OX is the resultant cflFeeC
now practically at rid[it angles to the impressed E.M.F. of the circuit. By
raising or lowering, thus changing the position of the short-circuited tura,
the magnetism of the shunt field can he shifted back to the proper aa^e.
giving the 90 degree phase relation and adjusting the meter so as to nad
eorrectly under all conditions of power factor.
NoTB. — This power factor compensation holds true only for mppnar-
mately the frequency for which the meter is adjusted and^ if highest accuracy
induction meters be capable of operating over a wide voltage variation without
impairment of accuracy, and freedom from error due to voltan variatioiii
is accomplished by the des^ign of the shunt magnetic circuit, ^y referring
to Fig. 4 it will be seen tht«t the shunt magnetic circuit is so arranged thet
the neater portion of the magnetic lines generated by the shunt winding
are shunted across the narrow air gaps FF and do not pass through the disk,
thus cutting ftr damping its action and thereby impairing the aecoracy.
While the exact leakage across the gftps cannot be accurately determined,
it is a large proportion of the total flux generated so that a comparatively
wide variation xrom the normal voltage has practically no effect on the
inrt«>>Sai«Miatration owing to the snuill percentage of damping flux whiflh
TBSTtNOHOUSK IKDUCTION WATTHETERfi.
^nn 7 muatnlM a tvpio*! voltue ourva t
will be Dotsd thkt M. voJU«ii nofe Irom 60 i
nn&l vo[tAffa doa not EOAteruJly impiur the lu
n tFi(, 8) «
htiiu tiflld type prei
is foUowi: High n
lower ioHIdi I
Fio. 7.
fiiation; hlA nfio
bwrinK: improTed iwu
Iflakase flap of shunt ouii suu uiwunswu uj
power factor mod frsqueocy ■djustmsnt: B«sursl« on uon-4Ddustive or
InduGlivs load*; freedom Inun Mlaet c4 atrfty GtMii; pecnunant nwsDaU
DUffDeticBUy shielded; li^t rotstlni element (16 crsmmes): luulTsated
by voltas* vuistion fromSO per cent to 136 peroenlof nomwl; unaBeetsd
by wide wUtlooi In wave lorm uid trequenoy; trMdam fioo ntUlnc or
t refio of torque to wei^t: Impnived
nTvd iielf oilins lop bauinc: li^t Kwd t
I ehunt ooil and unaffected by Bui of aai
and frequency adiustment: B«sural« <i
Fio. 8. Typo "C,
i
1004
ELBCTRICITY METERS.
Figure 0 iUustrates a House Service P^ljrphase Meter and Figure 10 the
Polyphase Switchboard Swvioe Meter.
0^
POLYPHASE
INTEGRATING WATTMETER.
WE8TINQH0USE
ELECTRIC & MFG. CO.
PITTSBURG, PA., U S.A.
Fig. 9. WeetinghouBe Polyphase Induction Meter (House Service).
Fio. 10. Westinghouse Polyphase Induction Meter
(Switcbboara Service).
BIHQLB-PHASE INBUCTIOM WATTHKTKKS,
(Geogisl ElectHc Co.;
Th«e Diet«r» (Fig. 11) are of the
BBine genenJ type m the W«tin(p-
buDH, but differ in mechsiUiiu oon-
slruatioD Tba salient feat urea clajmed
Ate pTMllsaUy idantieat with time ol
tbB Watiu^KiuH meten.
The beerimn, however, are of »
alurtBlookad.-
er niniilBi to that of the Thi
(Fig; 13)are8l8c. of tl.e rotjiting fial.i (yp«. but employ a
■tor instmd of a Hwlt, The lighl load Bdjuelmml i» aBected
BI.ECTKICITY HETBUS.
cimslio>iiy idaui
WortiD^uMue ■
5
Fro. 13. Type "E" Meter
(Cover Removed). Fort
Wsyne El«>. Co.
•nerc pauiiis Ibroucfa
D. C, INTEOBATIKCI BIBTEB. 1007
PrtBdplB mt OiHiTadoB. — Tbepiineii^ cooperation Duyb«andv-
•tood by refsring u Fig. IB, and tbB followinc desoriptioD : A — A ara
(he poJeg of ui eleotromsKnFt energiKd by tha poUotial coil which, thnni(fa
tbfl line, thiis (orming Ihs voLtsga nlenieiit
tbe Una aad fomu the oumnt alemffit ctf
the meter. In npocitiv emedins lOeob-
irbnt the disk oaiy carriai a certaLi] poi^
7™dijS! '■
_ motor (Jetc
ita edgAB pjun between the poln of two pei^
^n™ b'.™ loounted™". Somr^otTrfuji
which is suitably pivoled or iiupeaded.
The third element of the meter, n»mrfy,
the regiatsring mechiuiapi. ia Dot ihown.
but. in eommon with other (oirns of motor c
meiere. la driven by a suitable gearing
aotuatad by the ratkbla ihaft.
i
BI«<H«BtBi7 UtMrraia of SttivaHfl It. C IIIflMr.
From the arrows on A - A it will b^ wen (hst the field generated by tha
potential eoU threads the two air saps and in doing eo cuts or nefleei Ihttnigh
the copper disk D. The digit D being in xriin with the load ia. Iherr'"—
~*J^ 'A"A*aiS
1008
BLKCTBICITT MBTBBS.
V
ia at right an^es to thia fidd. As is well known, a oonduotor free to
and carrying a current whose direction of flow is at right angles to a
field will tend to move out of the fixed field.
As the disk moves from its initial position the eurrent enters at a
point on the periphery of the disk which is again impelled forward, and this
constant change in point of current entrance to the disk produces a coa-
tinuous rotation. It wiU thus be seen that the meter, in common with the
Westint^ouse D. C. meters, operates as a simple motor driving a nukgneU^*
generator having a short circuited armature.
The Sangamo meter differs, however, in its construction from that cm-
ployed in the commutator D. C. meters in that the voltage element is statioe-
ary rather than rotable; the current element being rotable rather thaa
stationary and instead of employing a commutator and brushes to lead
current in and out of the rotaole dement, or armature, it is submersed in
mercury contained in an insulating chamber having contact pieces at each
edge to which the circuit connections are made.
Figure 15 illustrates a meter as actually constructed. Hie a&eroiuy b
contained in a dome-shaped chamber and not only serves to conduct the
current to and from the armature, but also tends to buoy up the disk and
relieve the pressure on the lower bearing.
The full load adjustments are accomplished by varving the strength of
field through which the disk passes, and the adjustment at
the magnetic
light load is accomplished^ by^ a compounding coil so located as to
field generated by the potential coil.
t the
iL. C. Meter.
This meter has the same general appearance and operates upon the same
principle as the D. C. meter, but differs somewhat in the arrangement of the
measuring elements. In the A. C. meter the main current energises the
stationary electromagnet and the shunted or potential current passes through
the copper disk. Compensation is provided for light load and inductive load.
urnioHT TCScoinra mctjbii.
This instrument is for use in oonneotion with a watt hour meter for da-
terming the maximum use of current during any given period ; or may be
used without the watt-hour meter in connection with any electrical device
for which it is desired to know the maximum use of current, either direct or
alternating.
It is slow acting so as to take no account of momentary spurts, such as
starting an elevator or street car, and is rated to record as follows :
If the maximum load lasts 5 minutes, 80 % will register ;
If the maximum load lasts 10 minutes, 96 % will register ;
If the maximum load lasts 30 minutes, 100 % will register.
The following
glass and
reading. As shown, one leg of tbe circuit passes around a glass t>ult> wnicn
is hermetically sealed, and connected to a glass tube holding a suitable
liquid.
T, Terminals.
B w, House wires.
B w, Resistance wire.
E B, Heated bulb.
B, Air Bulb.
Indicating tube.
L, Liquid.
^ Direction.
Wright Discount Meter.
XXTKS BEABtNOS. 1009
Tbe heat dne to the cnrrsot paulns in Iba olroait eipuida the »b In the
bulb, vhtoli for«ei the liquid down In tbe lett ooliunn luid up tn tbe right.
Blioiildihe qoutitT of heU lie snchu to force eome of the liquid higb eDough,
It vfll fail o>er Into the eeotnl tube, where It mu«t itaj nntil the liutro-
ment ti readjusted. Tim waie hack of the sentrai tube ie eallhrated In am-
pere* on ibe left and In watt* on tbe right. Af t«r r«>dliif and recording
the indioatlon for any period of tims, tbe llqald Is letumed to the outer
tabaa bj almpiy tipping up tbe tubea. et«., whlnh are hinged at the top
eouneetiona for the purpoae.
The readings of the demand Meier or tUteotatl meter, either of vbloh names
Are used, together with tliose of the watt-honr recording meter, fumUb a
basis for a more ratlona] system of ohargjag for electriclt j than has been
This subjeot is bslDg taken up by many of tbe hu^er electricity
anpply eompaulee.
The I — ' '^"
luatmmeDt I* handy to use In circuit with a transformer to ib
— -'iiufid eompares with the transformer capacity;
II to show now beaylly they ma; be loaded.
i
Fio. IT. VlBuai HTot Tjpa
Fia. 18. Pivot Type Bearing.
I BBAarircM. hkoisvaks aich com-
HIJTATOMS.
Two forma of lower bearinn are in cBneiHl use In both direct s
s. EWT? and 18 repp ' ■
Figure 1
p^iihedst
and hi^ily poUatuid eieel pivat testlog on a oupped sapphire,
ne end-stone or oupped diamond jewu.
a rolling type ball bearing farraed by a small hardened and
ball rating between two jewels, one of wbieb ia attached to
r
1010
ELBCTKICITY MBTBBS.
WSMIM
l*C« or MU.IMID OtOTN
MAKCD IN JIWIUM Olt
•TUt Ml
JSWCU
the armature shaft and the other to a
fixed support. By this oonatruction a
rolling action is secured as oontnsted
to the rubbing action of the pivot
bearing.
Both types of bearings are «xta»>
sively employed by meter manufactur-
ers and each has strong advocates.
The pivot form of bearing is invariaUy
supported by a spring suspension, ivhfle
with the ball bearing the spring ia cmly
resorted to in the direct-eurrent meten
having comparatively heavy moving
elements.
The registering mechaniams of the
various tyi>es of meters are quite simi-
lar in appearance, dififering principally
in the method of construction. Fig.
20 illustrates a typical form of register-
ing mechanism employed in both D. C.
and A. C. meten.
To reduce the variable nature of the
contact surfaces of the commutator
«. «/v n »• rr. n ii «> ^^^ brushcs It Is oustomary to em-
Fia. 19. RoUmgType BaU Bearing, ploy non-oxidising metal in the con-
struction of these elements, thus reduc-
ing to a minimum ohansses at this point. Fig. 21 illustrates the damping
disk, armature and commutator mofUnted on the rotable shaft.
JCWBL SOIICW
mm MUT
l^iattinetcr.
The prepayment idea for
the purcnase of practically all
forms of commodities is rap-
idly growing, for the vending
of practically all forms of com-
moditi», and is now receiving
recognition in the electrical
field. Like the installment
plan of payments, the prepay-
ment meter appeals to a class
of people who are accu»-
Fio. 20. RegLstering Mechanism.
tomed to receive and spend their monev in small quan-
tities. The success of sew companies has been greatly
aided and furthered by the prepayment meter, and its
use in the electrical field should prove as great a suo-
cees as it has proven in this field.
Prepayment meters are especially applicable in su]^
plving energy to customers whose total consumption is
relatively small and the collection of whose bills is a
very considerable proportion of the total revenue de-
rived. Their use reduces the amount of bookkeeping
and unavoidable monetary loss due to poor accounts,
for the service is such that before securing li^t it is
necessary that payment be made. This system, there-
fore, automatically collects its own bills, registers the
actual consumption, and when the energy prepaid for
is consumed, automatically disconnects the service.
In installations such as flats;, dormitories, barber shops,
caf<58, saloons, boot-blacking establisnments, eigar
stands, rented houses, or in any other installations where
Fio. 21. Rotating the volume of energy consumed is necessarily small.
Element of D. C. the prepayment meter will be found extremdy useful.
Commutating Type Central stations supplying towns having a large **float-
^eter. ing'* population, such as seashore resorts or college
THB FaKPATKENT WATTUKTEB.
to-wm, when tbe rap
of ncoounto. will find ,._,
Cnitn] Htationa fmiueotly uvs a oaiuJdaraUa □„,„ . ^ s.»..v»^^... ^..^
■re usuKlly backmrd in piynunla, kllbouafa they ultimstely pay their
bills. One melboil of [ondDf nioh ousUiiiieim to pay luck billg ia <o thnaten
diacontinuancs al Himce, but thia meChod ia only resorted to ae an eximae
m«uure. owing to tbe reaultiiiE UDplanasntniia and very pwibi* loss of a
Intimate revenue tied up even with cmWmora who will ultuuMly paj;.
the service, might be to install a prepaynunt meter adjuated for a higher
r«t« per k^r.-bcur than tbe regulamte. For instance, (ueuiniDg the norma]
rate 1« be 10 cents per kw.-bour, the meter may b« set at IS eenta per kw,-
hour, so that the cmlomer not only pays for the energy bdng consumed,
but also snidusUy pays up the old bdl on the installment plan. Tbe
majority ol suslomen would undoubtedly prefer thia method of payiog up
Fia. 22. General Eleotrio Prepsy- Fio. 23., General E
. After the
At the preqflnt ti
iderable number o
not undentand I
per year, and assuming the cost of generation and distribution is one-hsif
the gross receipts, it would leave a remainder or profit of tS, Ifhs the inleretl.
oolleetlon and maintenance cost. While the grow profit would not be very
advantage that a larne maiority of Itine new cugtomeni would gradually
uae Urger amounts of energy and in time come within the cIsbb of denirable
The use of eleetridty inereasca with the knowledge of ita advaotageg, aod
ELECTRICITY METERS.
tfa«ra is no Iwttiir wmy
siutomeni. Chu with tli«
With tlM preparmcot coeUr, diffi
kw.-twur
5
itndusina its UM ap«ouUly with
mitiAl nMa oui «uily b« mule, owii
IHt tint ths iBte par k— '- -
n the mslar biUa ud the .
suy. tlwtefon, pUoa melj
teroit rata to meet thr
vhiflti krua: for inatulM, A uinc-bDur 0O£i»1>-
luppUed throucfa a iDei«r aAjiaiBd
witS a, pr«p>yiaBDt meur ouiuuineis [»! they
*n puniuaiac Jjcht tud not lEW--bourAr
ooniiflDtion with electno oDoldug uid hiKtiitf
■nslitliMB, whioh fiequcnlly are siipiilied with
than ia cbarnd lor Sishtinit, TLeae appliaijcei
maybe euppLied through a prepayment ineirT.
and thU Byalem baa the addLtioruJ advantage
ouraltlyjiHl what the deolrio moldrn or hal-
ine outnt u oosting for the naulla obtained.
Fio. 24. PrHiayinent At- c
taihment fnr Onarml i
hJ fonns ^^ comiDa^
fing illiutrationi. Ejnentialty the lue-
ooniunotion witb a ipecial reauter, an-
Bwitchins device aacl ooiri obuM. n*.
Pia. 25. Fort Wayne Prapar-
INTBORATINQ WATTMBTEB TESTING.
19ITS«nA'X'll«CI H^ATTMETKB TH«XZIie.
I quite sencra.\ly teoasaiied tbat inteKrstms wattmtiUin an
-intoiiked in mj accur&te and eScicTiC conditLoo by oninpfirine (1
la intwvfela with koowa BtaadArde, aad ic ia obvious ttiAt tbe 0<a]
nkeats they flhould have a wide opentinc ruw
may ba obuinad luimuily by a Ions Kalg.
'ben poeaible the mace thouhT be further in-
wbii^ may b. ^ , ^
lot tutrame Mmimoy and " nooondary
■landanls [or use directly with Ibe servii
Cksckt^ af MBcsBdarj MUad ^.
8econ<lary elandarde ehould be frequently checked -
with the prboary standard^ It- ' ' — ■-
cbeckiDc varylni laiinjy with lo
■tkndanla M Inst onoe a moDin. capaaauy wnen
■uch (tandardi oontiat o( iodiciatinB meler*, owin<
to the fast that all portable indieatiDg maten ara
more or leu ddisate and (be njufb uiAite attendant
OD oaininercial teelioE is liable lo malenaUyohsiige
the calibnitioD.
h local nwiditioiM, j
S3J
wattmeter with the
rter^^nt
bankof incanducent
i
Flo. 28. CoDneotiona for Comparins Seoontlaiy with Primary Standanl.
1014
ELECTRICITY METEBS.
metera, it being somewhat difficult to secure accurate rmdings on a dreutt
having a badly fluctuating voltage. A convenient arrangement of load
is shown in Fig. 29, and consists of a bank of lamps of ai£Ferent candle-
power ranging from 4 to 60 C.P., these lamps being arranged in oonnectioa
with single-pole, sin^e-throw switches so that the smaller sises may be
thrown in circuit individuallv and the larger sises in groups. The arrangi^
ment shown may, of course, be varied to suit local conditions.
In circuit with a portion of the lamp bank is placed an adjustable re-
sistance or rheostat for use in obtaining exact current values and also to
assist in maintaining a constant load. The water rheostat is very con-
venient for this class of work as the load can be varied quickly and with
perfect uniformity. The resistance of the water rheostat can be readily
changed to almost any value by chanpng the strength of the solution.
Having made connections as above, it is now only necessary to take the
readinei on the portable meter at convenient points and to compare
LAMP BANK
^
/
4)4)4©^ ®
SINGU POLE
SWITCHES "
ADJUSTABLE
RESISTANCE
O O
+-1 PPIMARY 8CG0N
^ STANDARD STANOA^
RESISTANCE
OQOOO
Fio. 29. Lamp Bank and Connections for Comparing
Secondary with Primary Standards.
readings with the true values as given on the primary standard. It is
considered good practice to check the portable meter at each of the mailced
points on the scale, simply estimating the error of the intermediate points,
thus showing the error very closely at all points of the scale.
Cbfickfnir CallbnUMom of Portable Standiard Imtot '»<*->'
fVAitiiietor. — If the portable rotating standard meter is used as a second*
ary standard, it should be checked with a primary standard wattmeter from
time to time and for this punxw^ should be connected in the same manner
as the indicating standard shown in Fig. 28. To make a oompanson of
the rotating standard with the primary standard it should be properly
connected and placed in series with a primary standard of approximately
the same ampere capacity. , . . ,
I<larlit I<OMl Test.— -The load should now be mamtamed ponstaat at
approximately 4 per cent of full load and the pointer revolutions of the
rotating standard timed by a stop watch. Having obtained the tune oon-
INTSGBATIKO WATTMETER TESTING. 1015
sumed in making a certain number of pointer revolutions, the watts should
be computed by the formula applying to the particular meter under test.
Vall-Mfoacl Test. — The meter may be tested on other loads ranging
from the light load to full load, but as the calibration curve of the rotating
standard from light load to full load is practically a straight line, it is unnec-
eeaary to take readings at other points than light and full load unless
extreme accuracy Ib required. If this is desired, raadings may be taken at
several intermediate points, from which readings a curve may be plotted
giving the exact ealibraticMi of the meter at all points.
Miectiom •f Prlisarj •taaMlard Meter Cap«clty. — In com-
paring secondary with primary standards, care should be taken to select the
windings of the primary meter having a capacity nearest that of the meter
under test, in order that it may be used at the highest possible part of the scale.
This rule aJso applies to the comparison of service meters with secondary
standards.
Teattatr Scrrlce BKeier*. — For the testing of service meters, either
the "portable indicating" meters may be employedin conjunction with a stop
watch and the reading commuted by the use of a calibrating formula, or the
meter may be compared with a portable standard integrating wattmeter.
To use either of these methods the standard should be connected in circuit
with the service meter as shown in the diagrams usually accompanying
each meter.
Where meters operating from series and voltage transformers are to be
tested, it will usually be found advisable to test them as 5-ampere, 100-
volt meters without using the tranrformers. If such meters are to be
tested under the running load, the standard may be connected in the
secondary transformer circuit cl the meter under test, using the fr*ampere,
100- volt coils of the standard.
Te«tlar fteiTlce Meters wltb fttaadArd Indlcattef Meters.-*
To conduct a test with the indicating meter it will be necessary to hc^d the
load as constant as possible and while noting the reading of the standard,
count the revolutions of the disk of the meter under test, taking the time
by means of a stop watch. To eliminate personal errors several readings
of at least one minute each should be taken and averaged. To compare the
reading of the meter with the standard, it is necessary to use a formula
pertaining to the particular meter under test.
Vse ef Step Watcll* — When employing the indicating wattmeter
method it should be remembered that the stop watch is not infallible and
should be frequently checked by comparing it with the second hand of a
good dock. For this purpose a clock m which the pendulum beats seconds
or half seconds should oe used, starting the watch with a certain beat of
the pendulum and having allowed the watch to run several minutes to elim-
inate perM>nal errors, it should be stopped on the same beat of the pendulum
on which it was started. A little practice will enable the operator to check
the watch within .1 of a second without difficulty.
Testiar S«rTl«e Meters wttli Portable Staadartt late- *
iprattaMT Wattateters. — If the integrating standard is used for tenting
single-phiase service meters, the operation is much simpUfied, as the use of the
formula and stop watch can be eliminated. To conduct a test by this
method, the standard should be connected as shown in Fig. 30, and the
oonneotions so arranged, if possible, Uiat the capacity of the standard will
be the same as that of the meter under test. The proper connections
having been made, the load should be adjusted to the desired value and a
direct comparison made of the number of revolutions of the meter under
test with the number of revolutions shown on the counter of the standard.
In common with the indicating standard method, readings should be taken
for at least one minute to eliminate personal errors. The percentage of error
in the meter under test may bo found directly by dividing the number of
revolutions oi the service meter by the number of revolutions made by the
standard meter ; that is, if the meter under test makes 10 revolutions while
the standard meter shows 10.4 revolutions, the ratio would show the meter
under test to be approximately 4 per cent slow. The above applies only
when the meter unaer test has the same full-load speed as the standard.
In order that the standard meter may be conveniently employed m
testing meters in which the full-load speed is other than twenty-five revo-
lutions per minute, the following table has been prepared as applying to
Wsittnghouse. GsnSFal Electric and Fort Wayne meters. By the use of
ELECTRIC ITT HETEBS.
3
11
it
1
1
•bI
m
s
s
-
82
2-
a
S
'^
a
5
m
a
s
ss
s
a
;
S9
a
;;
m
3
s
s
S2
t
a
S
S5
;;
s
ill
5
s
R
3
"
^
"
»s
J
:
m
s
3
!?
^
S2
a
s
3
a
3
;
ill
s
s
8
i
^
^=
E
a
s
Si-
a
R
1
li
m
a
„
9
^
»■;
R
;
a-
a
a
m
a
a
;
S
^
^5
s
ss
a-
5
&
m
a
s
s
s
sa
s
3
a-
^
a
1
sii
a
3
s
s
sa
X
i?
a-
S
g
1
sll
s
a
S
a
"
■a
n
s
3S
a-
S
s
i
m
a
i
a
^i
sa
2-
8
s
!5
8-
J
*
<
m
!
s
s
=
2-'
5
3.
a-
I
1
-sgs
"sas
e>o«o
:=
■"2
**
as
83 83
1
i
11
oo
ll
iiasa
= ;
s ;
3S
s i
SS
■duly
"28?
"285
iiS
""
"2
"2
22
as
as
i
■■■^i
w»
•m
1'
X
o
■iia
•»
•o
m
"
9
"
;
• m
IS
g
^
3
im
«
3
«
J
j'-'^
3
^
S
!S
1
im
S
i;
s
t
1
Ms§
8
"
8
r
1
: m
i
;
a
;
'
Sf sfl
Z
a
;^
1^ Si|
s
t
!?
i^^i
2
5
s
i
^*i
!■
it
s
srs
n
*
s
si
s
'
»ji
*
s
n
"
ft
uodiuv »l
H tuKpawts
-ss
"SS
gs
as
1
.jM
°°;
°°
1
irii
8SS
ss
'
1S?
"SS
»2S
as
as
1
iii
If
1
I
k
1018
ELSCTBIGITY MBTXB8.
this table any one of the three makes can easily be tested with die
standard.
In explanation of the use of this table the following examples are fpv«
(1) l£ it is desired to test a Westinshouse service meter by usins the
rotating standard, the two meters should be connected in series and loaded
so as to give one revolution of the disk in approximately one minute's ttme
for a light-load test, and for full load, twenty-five revolutions of the disk in
the same time. The number of revolutions made for these two loads by
the standard — if the service meter is correct — would be one and twenty
five respectively. K the number of revolutions made bv the standard b
25.77 tne service meter is three per cent slow at full load. If the niunber
of revolutions of the standard is 24.27j the service meter is three per cent
fast at full load. From this example it will be seen that the accuracy eaa
be determined for anv speed within six per cent fast or slow, reading same
directly from the table without any calculation whatever.
(2) If it is desired to test a five-ampere General Electric meter the load
can be adjusted to give say — two revolutions at light load and thirty
revolutions of the disk at heavy load in approximately one minute's time.
If the meter is correct the standard will show 1 .8 and 27 revolutiona respcc-
tively. If the standard shows 1.86, the service meter is three per cent siov
LOAD
PORTABLE
STANDARD
llfTEGRATING
WATTMETER
WATmCTBfi
Fio. 30. Connections for Cheeking Ser\'iee Meter with Portable
Standard Integrating Wattmeter.
at liriit load. If the standard shows 1.75 the service meter is three per
cent last at light load.
(3) It it is desired to test a five-ampere Fort Wayne meter the load can
be adjusted to the same value as with the General £lectric meter. If the
meter is correct the standard will show 1 .5 and 22.5 revolutions respectively.
If the standard shows 1 .54 the service meter is three per cent slow at liipbt
load. If the standard shows 1.45, the service meter is throe per cent fast at
light load.
If it is desired to test three-wire meters, the standard should be con-
nected into the circuit with one side of the meter under test, the other side
of the circuit being left open. When the test is conducted in this m^ner
the pointer of the standard will revolve at a rate twice as fast as the disk
of the meter under test, which has but one-half of its current winding in use
during the test. To effect a direct oompari.son, the number of revolutions
made by the meter bing testeed should be multiplied by two.
TestlBi* Metcm ror Accaracj on Inductive XHNS«U.-^When
it is desired to test meters for inductive load accuracv the necessary load
may be obtained in one of several ways as outlined below:
For obtaining the inductive load from a single-phase circuit a set of two
or more five-ampere reactance coils, such as are used in the multmle A. C.
arc lamp, will be found convenient. The coils can be arranged to give
almost any current value, when used on a 110-volt circuity up to 25 am-
peres by means of series parallel oonneotioos. The taps which are brought
IHTBQBATIHQ WATtMBTEB TESTINQ.
•xis
arc uarf ul In oblAinii
OQ induBtive IcAdi, lh« powar futor of wb
a power-fMtor metar or by tha uH a( i
t olosaadiuiitniMitti of ounvnt
□an be dirsclly dMonmnod hy
OAU of uie vult-ADip«r« rMdina n
multipLied by the votto^e of the oi
catiDE Tattm«t«r u lued. the w&tt voJua ia &t onoa mpparent-
ttapoanl jntesntin^ meter ia used, however, the ApproxiiuACe n
be obtAiaed by Dotinc tha apaed of the pointer whiah should r
aa fast as it would IT the suae volI-Ampens wen applied ai uuiy powir
taMor. Tha fuU-load speed at (ha rotating standard oparating at the ow
KLECTaiClTT METBBS.
f
t
t
f
c
I
..e inplutitaoeak is exactly 90 degtecs tlie
, ,( .fro ;H>wcr factor or quadrature may also be ob-
\ ^^ . /■^^-;.>i.iai9e circuit by connecting the
-.'cut ootb in phase A, taking the
If
H^ in phase
placed betwi
^.^ vtni^ piacea between phases AB aikd AC.
>aij^c«d on each phase to obtain the desired reaoh.
^;(j^jnmg this condition from a three-phase cirenit ii
-t J>>tMks« to two-phase and connect the niMter into the
( All in Fig. 34. This method neceositatea the oae of
'. iA>iag the "Scott" three-phase to two-phaae coe-
oa:>a$ this method may be more oonvenieiit tlkaa the
' >J. as >t eliminates the neoessitv of wimi»if^|njny the
jtf 'oree-phase circuit, it being only necessary to ^tv
•ue phase of the two-phase circuit for a load. Having
'. o quadrature with the potential, the test should be
aiiineJ >° ^® preceding paragraph describing the two-
C* Me^'**'"^^'' ^^tins D- C. meters a testing arraniev^
t^iaC ,.th»t shown in Fig. 31 may be employed and the meters tested
pown
TRANS.
OLAliPS
tAUPS
C( '
ho
u,' :
It ;
I'..
Ii.'.
i'
of »}>.
th.> ••
of t»i,
T«5ii».
it i^ •:
nuxv ^•
PORTABLE
STANDARD
INTEGRATING
WATTMETER
INTE6RA1
WAnMETER
POWER
TRANS.
."^itaining Inductive Load from Two-Phase Circuit and
«, Integrating Wattmoter as Standard.
^%Bt
«-ammeter method or by the indicating wattmeter method.
h\s would not be employed, but in general the method of
-,- tin for A. C. meters previously described. Owing to the
;>eing different for the shunt circuit and the disk, it is neoes-
• leter be run lon^ enough before test to allow it to reach its
ug condition, which is approximately 15 minutes.
Pwlypliaae ••r^-ice Meters. —As the polyphase meter is
:ti4ie-phaae meters having a common aha/t and registering
general instructions for the single-phase meters wm apply
_ "-i^ Xhe calibration and checking of these meters,
~nore complicated and the following geDcral in-
>ce in the testing of this type of meter.
r Pol7phaa« ]II«tev*« — As yet a rotating
) is not (December. 1907) on the market> aoa
■ »o
IKTSaRATINU WATTHBTRR TKSTIKO.
Fra. 33. ObtKining Inductive haaA from Tbr««-FhitM aniuit.
To teat ft polyphAs« meter it a cOBtomary to employ &q Artificift] loftd
KDd Iwt «ch Hiae u ■ Hingle-phiue nlemenl. Ta tnit n Belf-coDlained
b* nude u ■bowD in Fl(. 35, indTfor t«atla| ■ meter uaini trtUBformen
CUHREffr CCm. JHETEI
— nrfmrX- —
(Trnnr
-o-PhoM Comi
In Flc 3fl.
T»1lf>OI9T SmiTCK /
^ ^ INFtGR
muTM
CATIMG •^'^
(r(o)ii """HI t
<
Fio. 3fi. Conne
1022 BLECTBICITT METERS.
mulljplr tbs disk ravolutioni bj' two or divide tha oaUbniUiiK n
by two. The tat should b« flooduotAd in th« suae roiuner la wbi
ioa Binsle-phsn metum pnviausly deacribad. It will ba notad tin
poMntiftl elements of the lerviiw metw ere enereied, this bejns a
la poIypliBee teetiof.
LOAD ^*^' f^Kt g-fft* /^~i?^- n
^-'^ llfTtGIUTM
WXTTMETER
Fio. 36. CaDnwUou for Testing Poly^uwa Uet«r Emplorios
Traostgnners and Using SinglfrPbue Standaid.
J@tlJ POLYPHASE
•/S\! iHOltWIIMS WAHMETER
5:
OonnecUaiu for Tesling Polypluue Meier Employinit Tnne-
'S. Tatint on Itunnini Load and Using Folypliase Suuidoril.
INTBOBATTMO WATTMKTBB TB8TING.
To tMt ft polfphue meter on tha nmniag load. euDDMUona aOould b«
' maila u shown in Fiei. 37-38 uad tha Mat oanducted in the aama munar
■a for einsio-phaae tucitiK- Cara should ba axercisad to coaneot tha potan-
tiftl cJenwiit to the Huae point to avoid daDgn- of one QietAr m^iaunoff the
watt loas of tha othar.
andard IntwraEina iiatt-
H ingtasd of Uia in^eatinv
r ..jater ihould be onnneotad
^ - Jard intHtniting meter aubatituted
.-• iodicalinc meter. Whan >o ooonecled the diiE revolution. o( tha
polyphaae matar abould ba nmltiplied by two and diractLy eomparad with
-u* w^*.*i»- .*.*«^.»J i^ *k:.k «» :.^^*.. ..•;»«- *<^- -dnde-phftrt taflting
lyphaae maMr may
.. _,„ , .._j pinsla-phaaa portable
neter may be UKd for checking polyphoae me
mttmater. For ihii purpoM tha pnivnh...
a shown in Fiff. 3fl-3~
I
i
Fta. 3a Connections
) oonneeted in Mrien. in which caK tha nervioa and l«et meter dieka will
Non: — In all tenta o( polyphase meleni both potential eoila miut be
mneeted in circuit and anargiied. PolyphsM matem ghould be given
le aama teats at liiiht and fuD load, an (he sinKle-phaae meCara and tha
Line adjiutmenrs apply-
■errU* CosnectloiH afPolrpkaiw Meten. — Great cure ihould
Hng moda exactly in accordance with the pmper diagranu. This is
iicins exct^va arroraou inductive loads'aud" sUlT^e ^e"meter roU(«
jDneetions by alterni
u power faeter ia de&nitely Iuiowd, II tha i
1024
ELBGTfilCITY MBTEBS.
a thra^phase drouit operating at a power factor of lew than 50 per
one element should oause the cusk to rotate baolrwards, and if the bJoov
alone is depended upon when installing the meter, it is ver^ probable
that the average man installing the meter under these conditions woold
reverse the side rotating backwards, thus introducing an enonnous error as
the power factor of the circuit changed. It is also possible to so oonifteet a
polyphase meter that it will run in either the forward or revene direetioa
on Doth elements regardless of the power factor, the meter either ruimiv
faster or slower than it would on nnit^r power factor, depending upon the
phase relation of the particular connection used.
The action of two single-phase metoni, or the two single-iihase alementi
oi a polyphase meter operatmg upon a thre^phase circuit, may be explained
by the following vector diagrams.
Figure 39 shows the phase relations between the current and potential of
each single-phase element when operating on a threfr-phase drouit at onity
power factor, one meter element having its series oou in A and its poten-
tial coil across AC and the other element having its series coil in B mad its
potential coil across BC. From this diagram it will be seen that the ear-
rent in phase A is displaced 30 degrees from its respective potential AC and
the current in phase a is also displaced 30 degrees from ito potential BCX
Fio. 39.
but in the opposite direction from that in phase A. thus giving the effect of
a lagging current in phase B and a leading current in phase A, ue resultant
bdng sero displacement, or unity power factor, on the three-phase ciromt.
From this it will be seen that at unity power factor on the three-phase ar-
cuit each single-phase dement of the polyphase meter wUl operate at the
same speed, each element operating at a single-phase power factor of about
86 per cent, or the cosine of 30 degrees. , , .....
Kgure 40 shows the condition existing when the current in the thrse-
phase circuit la^i 30 degrees or is operating at a power f^tor ^ 86 per ewit.
From this diagram it wiU be seen that the current m phase B lags behmd
its respective potential BC 30 + 30 degrees or 60 degrees, while the cur-
rent in A has been brouAt exactly in phsae with its respecUve potentttl
AC. This gives a condition where one single-phase dement is operatmg at
a power factor of 50 per cent (or comne of 80 degrees), while the otb^ ele-
ment is operating at unity power factor, its current and potential bdng
exactly in phase. Under this condition one dement will run twice as fast
as the other. Ox, Ov and Or show positions of three-phase current with
30 degrees lag. To show phase relation of each current with its respective
voltage. Ox is rotated about center A instead of O imd falls in phase with
its voltage AC. Current Oy is rotated about center B and falls 60 degress
behind its voltage BC. . . ^ .u * • au *t-
Figure 41 shows the condition met with when the current m the three-
phase drouit Ugs 60 degrees or is operating at a power factor erf 60 per cent
From this diagram it will be seen that the current m phase B la«9 its re>
INTBOHATINa WATTMBTBR TESTING,
1026
■peetiTe pot«ntial BC 60 + 30 dagraw or 90 decrase. while the euRent in
phAse A ia«B its potential AC 60 - 30 dei^rees or 30 degrees. This gives a
condition vmere one singl»*pliaae element is operating at seto power factor
or cosine of 90 degrees, while the other elemen^ is operating at 86 per cent
or cosine of 30 degrees. Under this condition one element has stopped,
the other element doing all the work. For clearness in showings phase
relations the centers of rotation of the currents are ohuiged as in Fig. 40.
Figure 42 shows the condition met with ^en the current in the three-
phase circuit lagi 90 degrees or is operating at a power factor of sero. From
this diagram it will be seen that the current in phase B lacs its respectiTe
Ktentiai BC 90+30 degrees or 120 doKrees, while the current in phase A
Es its respective potential AC 90 — 30 degrees or 60 degrees. As the
angle of lag in phase B now exceeds 90 degrees, the cosine of the angle is
the same as the sine of the difference between the angle and 90 degrees, in
this case minus 30 degrees, pving a power factor of minus 60 per cent in
phase B and a power factor of plus 60 per cent in phase A. From thii it
will be seen that at sero power factor of the three-phase circuit, one sin^de-
phase element ol the meter will try to operate at half speed in one direction
Fio. 42.
while the other element is trjdng to operate at half speed In the opposite
direction, the resultant of these two equal forces acting m opposite directions
being sero; hence, the meter as a whole will not move.
From the preceding explanation oi the phase relations of single-phase
meters used on a three-phase circuit, it will be apparent that the ener^ of
a three-phase circuit cannot be measured by the use of one standard single-
phase meter. It also shows why it is extremely important to have the
polyphase meter connected into the circuit in accordance with the proper
diagrams as, owing to the fact that one element of the polyphase meter
should tend to reverse its direction of rotation on a power factor of less than
50 per cent, it is not safe to depend upon the direction of rotation of each
element separately to determine whether or not a meter b connected into
the drouit properly unless the power factor is known.
The general scheme of connections for correctly connecting a polyphase
meter to measure the energy of a three-phase circuit is shown in Fig. 43,
the current coil of one element being connected in line A and its poten**
tial acmes A and B» the current coils of the other element being connected
In line C and Its potential coils across B and C.
If a meter should be connected, as shown in Fig. 44, with the current coil
of one element in line A and its potential across A and C and the current
of tiie other element in line C with its potential coil across B and C, both
■InnMiiilii of the meter will ran in either the forward or reverse direction at
1026 ELECTRICITY METERS.
all values of power factor at equal speeds, and will be either fast or dow on
all power factors other than unity, depending on the phaae relations of the
particular connection used. This erroneous connection should be ear^
luUy guarded against, and it^will be readily seen that this condition eanaoL
be detected by the common method used of opening one side of the meter
at a time to determine that the meter runs in the forward direction on each
element alone.
The effect of the connections shown in Fig. 44 can be seen by referring to
Fig. 45. If one series element of the* polyphase meter is connected in at A
and its potential element connected acroes AC, and the other series element
CtMTHttCatf
LOAD ( fl LINE
Potenfiai Coil
■ VSA/V^
Curr^ni Colt
FiQ. 43.
•
connected in at B with its potential element connected across BA. when
operating under 30 d^rees lag the currents Ox and Oy will be shifted so
that both will be in phase with their voltage and the meter will run in a
forward direction faster than it will at unity power factor of the three-
phase circuit. With one series element of the meter connected in at A and
its potential element connected across AB and the other series elranent
connected in at B and its potential element connected across BC, the eur-
Cunrenf Coil ^
PotontfaJ Cott
LOAD t ^ ^ LINE
PoHnHaJ Coli
— AAAAA*-
Curnenf OoH
Fio. 44.
rwits wiU be shifted so that both Ox and Ov Isg behind their respective
voltages and the meter will consequently run slower than it will at umty
power factor of the three-phase circuit. _ ^ ^ ^-^ •
Practical nietliodii of Cli«ckliir Co»»octlo»» •f JP^ly-
gliisse ]ltet«rs. — In cases where it is not positively known that the power
ictor is above 60 per cent, the following method may be used, which is
based on the fact that the sum of the two readinm should be positive, so
long as the power is in the positive direction, when the currents m the
voltage and series coils, as indicated by the clock dwgrsm, are m the same
direction, or within 90 degrees of being in the same direction, the j>net«rwiU
read forward. When the current in the series coil is more than 90 degrees
out of phase with the voltage, the meter will reverse.
First. By proper testing ^ith an incandescept tamp or a voltmeter,
obtain three voltage leads, A. B, C, having equal voltages between then.
nrxBQBATnro wattmstbr tkstino.
1027
1
Seetmd. Conneot these leads to the voltage eirouite of the wattmeters
I per Fig. 48.
TfvanL Oonneet the series transformer at A to meter whose poteotial
is oonneoted to AC, and secies trans-
former at B to metw whose potential
is connected to BC. See clock dia-
gram (Fig. 46) giving the phase rebk-
tions. In Uus diagram. AC repre-
sents the voltage on meter connected
at A, BC the voltage on meter
connected at B. OA the ourrent in
mfCter connected at A, and OB the
ourrent in meter oonneoted at B.
Fottrth. Change voltage conneo-
tion from AC to AB on meter con-
nected at A. If power factor is 100,
Uie readings will be alike with both
connections. If the power factor is
less than 100 and greater than 50,
the readings will differ, but be in the
same direction (either both positive or
both negative). If equal to 50, one
of the readings will be sero. If less
than 50, the readings with connec-
tions A() and AB will be reversed in
direction, with respect to each other.
F^h. The same test may be performed on meter connected at B, by
ehanging the voltage connections from BC to BA. If the power factor
Fio. 4S.
I
Fio. 40.
OA current in meter at A 100 oer cent P.P.
OA 00 current in meter at A OO per cent P.F.
OA 50 current in meter at A 50 per cent P.F.
OA 40 current in meter at A 40 per cent P.F.
OB current in meter at A 100 pcur cent P.F.
OB 60 ourrent in meter at A 60 per cent P.F.
OB 50 current in meter at A 50 per cent P.F.
OB 40 current in meter at A 40 per cent P.F.
1028
BLBCTBIGITT MBTBRS.
IB 100, the raadingB will be alike. If less than 100 and more tlMUi 5QL
the readings will dmer, but be in the same direction. If equal to 50, one of
the readincB will be aero. If less than 50. the readingw with conneetioDa
BG and BA will be reversed in direction with respect to each other.
Sixth. If it is found from the above tests that the power factor is greater
than 50, connect the series coil of the meters so that both read forward.
If the power factor ie leas than 50, connect the series coil of the slower
meter so that meter reads baokwbrd, and the aeries coil of the faster meter
80 that it reacb forward.
The above description indicates the uae of two single-phaae meters, but
holds equally true for a polyphase meter oonsiatinfe of two aingle-phase
o»eter elements driving the same shaft.
Below will be found the formuln and testing constants to be oaed in oot
junction with the teating methods described on pages 1013 to 1023.
■1a f«r VMtlaiir <k« ftlialleBlMrirvr
' Tc Tdl the Exact Current Flowing al any Time.
Note the number of revolutions made by the small "tell-tale" index of
the register dial, in a number of seconds equal to the constant oi the meter.
The number of revolutions noted will correspond to the niunber of amperef
passing throuf^ the meter. For example: toe 20-ampere meter constant is'
03 .3 J if the mdex makes 10 revolutions in 63.3 seconds, 10 amperes are
passing through the meter. In order to avoid errors in readines, it ia cus-
tomary to take the number of revolutions in a longer time, say 120 aeoonds,
using the following formula:
No. of Rev. X Meter Constant
No. ot Sec.
— Current.
If. therefore, the index of a 20'ampera meter makes 19 revolutions in 120
aeconds the ounent passing is
19 X 63.3 ,rt -^
J20 — ™ 1" amperes.
The cover should be left on the meter while these readina are taken.
The constants of the different capacity meten are given bdow:
Meter Capacity.
Amperes.
Calibrating
Constant.
Meter Capacity.
Amperes.
Oalibniting
Constant.
5
10
20
40
22.5
33.8
63.3
126.6
80
120
160
253.1
386
506
Teetlngr FonMala for AballealM
ir««r
ttmm
The standard formula for testing all types and capacities, when using
o
indicating standards and stop watches, is Watts •* ^ /C in ?^ch:
R — Number of complete revolutions in time T.
T « Time in seconds required for revolutions R.
K — Constant.
The constant '* K " varies with different types and capacities aa outlined
on the following page.
^
METER TESTINQ FOBMUL^. 1029
Rattttips.— In all oases the volt and ampere values used with the
foimvhi are those marked on the meter. The fulMoad speed oC TVpes
••B" and '*C" metera is 26 R.P.M.
Fall-I^oad ftpcgde. — The fuU-Ioad speed of Shallenbenmr, Westinc^
house. Round Pattern and Type "A" Single and Polyphase Wattmetets is
60 R>.M. The full-load speed of Type '^B" siuola phase and Type "C"
single or polyphase wattmeters is 25 B.P.M.
For Shallenberger. Westingbouse Round Pattern Back Connected and
Type "A" Meters the constant " K " has the following values:
2'Win Meten {StnoU Phaae).
For sdf-contained meters K -■ volts X amps. X 1 -2.
For meter used with series transformer only (but checked without) K —
volts (as marked on dial) X 6.
For meter used with series and volti^e transformers (but checked with-
out) K -> 600.
For meter used with traosformen of either or both forms (and dieeked
with) K - volts X ampa. X 1.2.
S-Wire Meten (Single Phase).
For self-contained meters K « volts X amps. X 2.4.
For meters used with series transformers only (but cheeked without)
K - volts X 6.
Type " A '* Polyphase WaUmelen.
For self-contained meters K -• volts X amps. X 2.4.
For meters used with series transformers only (but checked without)
iC - 5 X volts X 2.4.
For meters used with series and voltage transformers (but checked with-
out) K - 1200.
For meters used with transformers of either or both forms (and checked
with) K - volte X amps. X 2.4.
u aa ft
Tke T—Unat ComatABt <* k " of W^eatterkovae Vyp«a
wmA *^ G *' Utetein la aa followa t
2'Wire Meters (Single Phase).
For self-contained meters K — volts X amps. X 2.4.
For meters used with series transformers only (but checked without)
K — volte X 5 X 2.4.
For metere used with series and vdltage transformeni (but checked with-
out) iiC - 6 X 100 X 2.4.
For meters used with transformers of either or both forms (and checked
with) K - volte X amps. X 2.4.
3-TFir« Meters (Sing^ Phase).
For self-contained meters K «- volte X amps. X 4.8.
For meters used with series transformers (but checked without) K »
volte (as marked on meter) X 12.
NoTB. — When the volta^ge marking of Westingbouse three-wire meters
covers both the voltage between neutral and outer and the voltage between
outers such as l(X>-200 volte, K — volte (between outside wires) X am-
peres as marked on meter X 2.4.
Type "C" Polyphase WaUmeters.
For self-contained meters K — volte X amps. X 4.8.
For meters used with series transformers only (but checked without)
K — 6 X volte X 4.8.
For meters used with series and voltage transformers (but checked with-
out) K — 2400.
For meters used with transformers of either or both forms (and
cheeked with) K — volte X amps. X 4.8.
<
BLKOTBICITT MBTEB8.
r*nnUt for TmHbc CI«aei«l HleMria KecArAlaC
Hu ataadard formula For tcatins nil types uid oapaoitLa vbai md
Indintinc ■Undanb and atop mMhlB b WaM— ^"" ^ ^ « j^ ^^
^ of "dirnal" readioc m
Xalile •r Claui
^
CapMdty
lOO-iaO VolM.
200-240 Volla.
500-000 Volte.
H^
por«.
a.K'
Minuta.
EuS-
7 6
as
IB
g
50.
3000
Xaltl*
atuK
per Be>«lBtl«
C<i^ly
100-130 VolM.
200-260 VolU.
BOC
MWOVolta.
HMsn
g
,S
^
?B
»
**
<$
u
^
e
z
380
W
2400
"D S" r«ir*hM« a«««n.
lOtt-lMVolta,
200-260 Volti.
SDO-OSO VolM.
W
«;?
«s;
Tiy,^r
»?
rasr
I
!■.
i
?
5S
IM)
«.
IS.
75
«i
Non:— Tsitliig Mutant liMlual wktt-honn p«r rerolntlDii of disk.
JVmala for VaattB): I
Ilia ftudsnl tonnut* lor la
idiiMlliic Muidardg and itop
S -Ttttiofx
la required tor mvolntioiu A.
at mnriMd on nwtw diik .
TeMlajr Canateata "K"
10O-136 Volt.. I a30-2«) VolU. |
T-tU.,
W.lt
^
I'l
f.
400
M.0
r«»tin.
WMlaper
i
i
1032
ELEGTBIGITY METERS.
The table given below will be found convenient In showing the per
fast or slow which a meter is running when employed in conjunction
., . „ , ^ , Watts Constituting Loaa _ « »-•
the following formula : ,_ ^, — ri—z—rrrsr- " ^▼^ Pw Mln.
" Testing Constant x 60
with
P«r Ceat Error VaMe for Fiftlia of » Second.
Time
in
Seconds
Per Cent
Time
in
Seconds
Per Cent
Time
in
Seconds
Per Cent
Time
In
Seconds
Per Cent
Fast
Fast
Slow
Slow
40.20
48.26
60.20
19JS2
00.20
0.33
70 JO
14.53
.40
68.61
.40
19.06
.40
0.67
.40
14.77
.00
47.78
.60
18.68
.60
0.99
.60
16.01
.80
47.06
.80
18.11
.80
lUll
.80
16 J5
41.00
46.34
61.00
17.66
61.00
1.63
71XN)
15J0
.20
46.63
.20
17.19
.20
1.96
.20
15.73
.40
44.93
.40
16.73
.40
3.37
JO
15.96
.60
44.23
.00
16.28
.00
2JS0
.60
16.30
.80
43JS4
M
16.83
JO
2.91
.80
16.4S
42JI0
42.86
62.00
16-38
62.00
8.32
724)0
16.06
.20
42.18
.20
14.94
.20
3J»
.30
10.89
.40
41JS1
AO
J4JiO
.40
3.84
.40
17.12
.00
40.86
.00
14.07
.60
4.16
.00
17.36
.80
40.19
.80
13.64
.80
4.46
.80
17.58
43.00
39 J»
63.00
13.21
63.00
4.76
73.00
17.81
.20
38.89
.20
12.78
.20
6.06
.20
18.03
.40
88.26
.40
12.36
.40
6.36
.40
18.25
.60
37.61
.00
11.94
.60
6.66
.60
18^7
.80
36.98
.80
11.62
.80
6.96
.80
18.70
44.00
36.36
64.00
11.11
64.00
6.26
74.00
18.93
.20
96.76
.20
10.70
.20
6.64
.20
19.14
.40
36.14
.40
10.29
.40
6.88
.40
19.36
.00
84.63
.00
9.89
.00
7.12
.00
13.67
.80
33.93
.80
9.48
.80
7.40
.80
19.79
46.00
83.33
66.00
9.00
66.00
7.69
76.00
80X»
.20
82.74
.20
8.69
.20
7.97
.20
30.81
.40
32.16
.40
8.30
.40
8.26
.40
3043
.00
31J»
.00
7.91
.60
833
.60
20.6S
.80
31.00
.80
7.63
.80
8.81
.80
20.84
46.00
30.48
66.00
7.14
66.00
9.09
76.00
21.05
.20
28.87
.20
6.76
.20
9.36
.20
21.26
.40
29.31
.40
6.38
.40
9.63
.40
21.47
.60
28.76
.00
6.01
.60
9.92
.60
21.68
.80
28.21
.80
6.63
.80
10.17
.80
31.88
47.00
27.66
67.00
6.26
67.00
10.44
njoo
32.07
.20
27.12
.20
4.89
.20
10.71
.20
32.27
.40
26.68
.40
4J»
.40
10.97
.40
82J8
.60
26.06*
.60
4.17
.60
11.34
.00
82.68
.80
26.62
.80
3.81
.80
11.60
.80
22.88
48.00
26.00
68.00
3.46
68.00
11.76
78.00
83.08
.20
24.40
.20
3.00
.20
12.02
.20
23.28
.40
23.96
.40
2.74
.40
12.28
.40
33.47
.60
23.46
.60
2.39
.60
12JS3
.60
23.06
.80
23.16
.80
2.04
.80
12.79
.80
33.86
49.00
22.46
60.00
1.69
69.00
18.04
79.00
24J06
.20
21 J6
.20
1.36
.20
13.29
.20
34.34
.40
21.46
.40
1.01
.40
13JM
.40
34.48
.60
20.97
.60
0.67
.00
13.79
.60
34.63
.80
20.48
.80
0.33
1 .80
14.04
.80
34J8S
60.00
20.00
00.00
0.00
i 70.00
14.28
80.00
85.00
"1
FOBT WATNB SINGLB-PHABB MBTEB8.
1033
Example. — If the revolutions to be made in one minute are completed
inezaetlv 00 aeoonds the speed is oorrect and the per cent error is sero, out if
the revolutions were made in 67 seconds then the meter is running 6.20 per
cent fast; if completed in 68.4 seconds it is 2.74 per cent fast. When the
time exceeds 00 aeoonds. the meter is slow. If it requires 03 seconds it is
4.70 per cent slow: if 04.0 seconds it is 7.12 per cent slow. The per cent
error will be found in the column after the time in seconds. The seconds
columns are divided into fiifths of a second so as to oonfonn to most stop
watches whose seconds are split to fifths.
Wwrmulm, for Veatinr Wort ITAjme Tjpm
u-mr ft
The standard formula for testing all types and capacities when uaing
indicating standards and stop watch is Watts — '■ — «— .
TaMm of V»l«Mi of CoBMtan* <«K" for I»lflorcBt Gi
itioe, VrP« ^WL** Fort UTa^Bo Mnirlo-Pliaao Moton^
(For metera whoee serial number is 344,900 or less.)
Am-
2-Wire
2-Wire
2-VVir«
3- Wire
2-Wir«
2-Wire
2-Wife
60 V.
110 V.
220 V.
220 V.
650 V.
1100 V.
2200 V.
peres.
" K."
" K."
" K."
••K."
" K."
"K."
"K."
3
• ■ ■
9
18
18
45
90
90
5
9
9
18
18
45
90
180
7*
■ • •
■ • •
• • •
27
• ■ •
■ ■ •
■ • •
10
9
18
30
30
90
180
300
15
18
30
54
54
180
300
540
20
18
30
72
72
180
300
720
25
18
30
72
72
180
300
900
30
30
72
90
90
300
720
1,080
40
30
72
108
108
300
720
1.440
50
30
72
144
144
300
720
1.800
60
64
108
180
180
540
1,080
2.100
75
54
108
210
210
540
1,080
2,700
100
72
144
288
288
720
1.440
3,000
125
90
180
300
300
900
1,800
4,500
150
108
210
432
432
1.080
2.100
5.400
200
144
288
570
570
1,440
2,880
7,200
250
180
300
720
720
1.800
3.000
9,000
300
270
540
1.080
1.080
2,700
5,400
10.800
400
300
720
1,440
1,440
3.000
7,200
14.400
500
450
900
1,800
1,800
4.500
9,000
18.000
000
540
1,080
2,100
2.100
5,400
10.800
21.000
800
720
1.440
2.880
2.880
7.200
14,400
28.800
1.000
900
1.800
3,000
3,000
9,000
18,000
30.000
{
Use these Constants for High Torque Meters.
15
30
13
Vi
27
54
54
90
54
90
135
270
270
540
540
1.080
1034
ELECTRICITY METERS.
Table of Values of Ooiutaa« <« K *' for IHITeveat Cmrnm
Ities, Type *" K " fort Wajne 81nrl«-PIUMe JKotoi
(For metera whose serial number is 345,000 or above.)
Am-
peres.
1^
0^
5
10
15
20
25
40
50
75
100
125
150
200
300
400
800
800
2-Wire
110 V.
" K."
9
18
27
36
45
72
90
135
180
225
270
360
540
720
1.080
1.440
2-Wire
220 V.
" K."
18
36
54
72
90
144
180
270
360
450
540
720
1.080
1,440
2,160
2,880
3-Wire
2-Wire
2-Wire
220 V.
440 V.
550 V.
" K."
" K."
" K".
18
36
45
36
72
90
54
108
135
72
144
180
90
180
225
144
288
360
180
360
450
270
540
675
360
720
900
450
900
1,125
540
1,080
1,350
720
1,440
1.800
1,080
2,160
2.700
1.440
2,880
3,600
2.160
4,320
5,400
2.880
5,760
7,200
2-Wire
1100 V.
90
180
270
360
450
720
900
1.350
1,800
2,250
2.700
3.600
5,400
7.200
10,800
14,400
2- Wire
2200 V.
((
•>
180
360
540
720
900
1.440
1.800
2.700
3,000
4,500
5.400
7.200
10.800
14,400
21.600
28,800
Table of Val
Tjpe *<1
of Coaatant
** Fori ITajai
' K " for ]»lirereat Ct
Poljpbaae ^irattatetena.
(For meters whose serial number is 344,999 or less.)
I
Volts.
Amperes
Oapaoity.
110
220
440
550
1100
2200
.. K/»
"K."
" K."
"K."
" K."
" K."
3
18
36
72
90
180
360
5
36
72
144
180
360
720
10
72
144
288
360
720
1.440
15
108
216
432
540
1.080
2.100
20
144
288
576
720
1.440
2.880
25
144
288
576
720
1.800
3.600
30
216
360
720
1.080
2,160
4.320
40
288
576
1.152
1.440
2,880
5.780
50
288
576
1.152
1,440
3,600
7.200
60
432
864
1.728
2.160
4.320
8.640
75
432
864
1.728
2,160
5.400
10,800
100
576
1.152
2,304
2,880
7,200
14,400
125
720
1,440
2.880
3,600 ,
9,000
18.000
150
864
1.800
3,600
4,320
10.800
21.600
200
1.440
2.880
6.760
7,200
14,400
28.800
250
1.800
3.600
7,200
9,000
18.000
.36,000
300
2,160
4.320
8,640
10,800
21,600
43,200
400
2,880
5,760
11.520
14,400
28,800
57.800
500
3.600
7.200
14.400
18.000
36.000
72,000
600
4,320
8.640
17.280
21.600
^•289
86.400
800
5.760
11.520
23.040
28.800
*7'S55
115.200
1.000
7,200
14.400
28,800
•
36.000
72.000
144.000
SANOAUO MBTEB8.
atrial Dumber ii 3'
Volt..
■■K."
"K."
■■ K."
J
36
73
144
iBtura. 3400 nK-HOanda
L tor obtuninc florrect HpAat mt &ay kiad la i
■vad mlta aflDitd. B equiUi eomct time in i
^ -y. If a-is theot
3f (TTOr Htiwll S
mater ii ful, if tl
■ given bdow wll
K'-'«uiUg ISdo. ■ndfor tbs e-ajniwi':^^
Seauala "K" divided Vw! If a-iii theobierved
ovofulion. the pei«iiUn of error eqiwli 8" minue 8, divided by S".
" K" u given bdow will ■!» apply In all oaa« ti
I for tba 5-aD
I
i
rCvBatoBlB " H " tmr ■wiffawo HM«n.
«n« ^:^»" II.C. .irf *yp« »■'
A.C.
U*l<_
48.000
00.000
240
000
OLKCTHtCITY MKTBBS.
«}KAPJHJIC
Fia. 48. Ccuonl EkaUis Curve Dmwins If star.
WUTIKOHOUSE UBAFHHJ BBCOBDINQ MBTBBfi. 10S7
a R, Ih* pt^t of
polypluM
1«™°— The volUnelwi and wnttmettra work
DjtiimomeWr" priaoipiB, uroployinK "
in uniofthe "Magnrtio. VwiB Type,'
4
'— Sprios controiled pen i
pivoted Bt I Kod curyins I
pen K. I
■ Pivoted support for pen ^
■ CoDtiol Bpriaa; hokUna Fia. 40.
cairut lh« r«wrd chart L.
■• ReoordiDK l^ua pen bntlnE on ofaart L.
' Rsoord chart drivv by clook median Um (not sbown).
tMrnrn me IKmtmr. — The amuture B is so looated in lelation (o the
oih AA tiuC when cumnt fiows tbnmgti them it la dttraoted by the
tio Add and tends (o ratate ihe iiupendecl element. Thii movanent
the rtHKirdiiiK pen K to move aemeg the chart L. a^inal the restrain-
.loQ of the eobtrol springs E, frtiich t«nd io return the pen to Hn)
1. The tumini or aotuaUnt forge o( the annature ii thug balanced
ths ooerolvB forse of the control spring and their point of bekDoa
asm* of the oumot flowing through the ooih.
'«V«>Mn«-ko«a« dnipUc HHwrdlar H*t*n.
9 AO iUuBtnttee the Watin^ouse " Relay Type " Graphio Recording
The metem are mad* as voltmeten. anuneten, gingle-phasa and
•a -wwttiaetan, poww faetor and inqviiui)' metan.
KLECTRICITT HKTBBS.
>. — The eongtruotioii of > vollmMcr <i iBi|T«mTii»<irMllr
Fin. SO. Wntioi^Kiun Qraptaio Rerordins Voltmetet With todi*
Fm. SI. DUcnunmatio Skateb o( WattnibcniM OnpUi
WSSTIN0H0U8B GRAPHIC SBCOBDINa METERS. 1039
A-B-O-D - Fixed coils.
£— F - Movable coils mounted on supporting structure pivoted
atG.
0 - Kvoted support of E^P.
H " Upper adjustable relay contact.
1 - Loirar adjustable relay contact.
J " Movable relay contact attached to movable dement Er—
F.
R - Pen aetuatinff electromagnet (left hand).
K'" Iron core of R.
L •- Pen actuating electromagnet (ri|^t hand).
L'* Iron core of L.
H *" Ann supporting iron cores pivoted at N and connecting
0 by pin bearing P.
N •- Pivoted bearing for M.
0 ■■ Pen arm connected to M by pin bearing P and provided
with guide slot at upper exwl which bean on stationary
guide pin R.
P -• Pin bearing connecting M and O.
R >- Stationary guide inn tor O.
8 " Recording pen arranged to pass across a suitable mov-
ing record paper T.
U " uelioal spnng connecting movable coil system and
movable pivoted supporting arm M.
keUmm at Het«n. — The system of fixed and measuring coils is so
inged that when current flows through them the left-hand coil B is re-
ed by A and attracted b^ B, the ri|^t-hand coil F being repelled, by D
attracted by C. Assunung the recording pen to be at sero position on
chart and connection made to relay and measuring circuits through
ling posts Nos. 1, 2, 3 and 4, it will be seen that the movable ssrstem
take up a position which will force contact J against contact I. A circuit
thus be completed throu^ the right-hand solenoid L and the dectro-
letic attraction will cause the core U to move downward, which move-
will turn M about its axu and through its connection with O cause the
o move across the chart toward full scale position. This movement
places tension on the spring U and continues increasing this tension
the core has travelled a sufficient distance to place such a tension on
t it balances the torque of the movable measuring sjrstem E — ^F and
the contact J away from I.
entire moving ssrstem. including solenoids, pen arm and measuring
nnajns in the position last assumed when the ** relay " circuit was
and the pen continues to draw a line which represents the voltage
or watta^ values as the case may be.
{
TELEGRAPHY.
Rbyisbd by Chabubb Thom.
Ix this oliapter only the instramento used in telegraphy will be notl«ed ;
and these, with their connections, in theoretloal olagranis only. For the
rarioiu details, whose presentation woald defeat the purpose of cleamoM
in this compilation, readers are referred to various woru on telegraphy.
Lines, batteries, etc., are each treated in other chapters.
AMSMMCAH, or CI<OIIBI» CERCVIV HBVHOl^.
The following diagram shows the connections of the Morse sTstem of
single telegraphy, as used in the United States. Tlie terminal stations only
are shown, and in one case the local circuit is omitted. Several Interme-
UNE TO TERMINAL
SOUNOCR
ilAIN
BATTERS
LOCAL BATTBnr
iY
UNI TO lARTN OS
~ TO RiTuiiN wait
Fra. 1.
diate stations (in practice 25 is not unusual) may be cut in on one cirenit ;
all the instruments working in unison, in response to one key only.
In Fig. 1 at either end u a key which, wnen open, allows the now nn-
attractMl armatures to be withdrawn by the retractile spring, S. Cloaing
the key restores the current to the relays, attracts the armatures to the
front stop; the local circuit through the relay points is closed, and the
signal is heard on the sounder. The attracting force of spring, S, is less than
that of the relay cores as energized by the current from the battery used
for a given circuit. It can, by 'fulling up " on the spring, be made greater ;
in which case the ffiven current is ineffective to close the relays, and if the
tension of spring, S, fs maintained, battery must be added to close the relays.
It is possible, therefore, by means of spring, 8, to make a comparativcuj
weak current ineffective to close the relay points. The significance of thn
will appear later in connection with the quadruples.
BUROPnAH, or OPSlf CIUCVIT MHMieP>
The following diagram shows the connections of one terminal station with
the line connecting to the next. The ground plates may be dispensed with
if a return wire from the next station is used, thus forming a metallic cir-
cuit.
This method of connecting Morse apparatus is used mostly in Europe, and
has two advantages over the American method .
a. The batterv is not in circuit except when signals are being sent.
b. When the key is closed and the current admitted to line, the coils of
the relay are cut out of the circuit, thus lessening the hindrance to the flow
of current.
1040
^
TELBOBAFHT.
1041
UNE TO NIXT STATION KIV
UM TO MOUND OH
TOMTUNN
FlO. 2.
prmcftica] telegraphy, the high reeistance of the line wire between the
tnal stations, ana imperfect Insulation permitting leakage in damp
ler, make it inexpedient to attempt to transmit 8lg>^8 over circuits
) lengths have not well-defined limits. Bat a oircnit may be extended,
lessages exchanged over longer distances by making the receiring
ment at the distant terminal of one oircnit do the work of a transmit-
ij in the next. The apparatus used for this purpose is called a re-
, and Is nsnally antomatie, In a sense which will appear later on.
I among the scores of repeaters, selection must be made of repre*
re types, — the tturee In most geiMral use.
Hllllk«m ]ftepe»ter.
tllowing diagram illustrates the theory of the Milllken repeater.
in general nae in the United States and Canada. The essential
/ ererr form of automatic repeater is some derice by which the
to which the sender is repeating not only opens when he opens, but
en lie closes.
I
l|l|l|l|ljlll}— ^G
MILLIKEN
REPEATER
FlO.8.
1042
TELEGRAPHY.
In the diagram is represented the apparatus of a repeating station in
which appear the instruments and tliree distinct circuits in duplicate, tuu:
the east and west main line; east and west local (dotted); east and wert
extra kMal (dash and dot). Starting with both ''east" and "west" Inys
closed and the line at rest, battery br\ whose circuit (dash and dot) ia eom-
Slete through transmitter, 7*', energises extra magnet, S\ attracts the pen-
ent armature, P', leaving the upright armature free, the pendent annative,
P, being similarly held bv battery, 6. In operation, the distant east opens
his key, relay, E, opens, then transmitter, T. through whose tongue and posi
passes the west line, which opens, and would open relay, W, and theraors
transmitter. T*; but at the moment transmitter, 7*, opens, the extra local
circuit (dasn and dot) opens, releasing pendent armature, P, which is drawn
by its spring against the upright armature holding closed the points of relay,
Tr, and transmitter, T^ana therefore the east Tine, which passes through
its tongue and post. When the distant west breaks and sends, the actim
basins with the west relay instead of east, and follows the same oourae.
C^hegWB Repeater*
In repeaters for lines worked single, the characteristic is a device in the
repeater which holds closed the main line on wliich the sending is being dons^
3
^0
QHEGAN
REPEATER
B
t
Fio. 4.
while the distant relay on the second main line records that sending; the
parts arranged to effect this result should act 9uickly on the "break^* and
a little slowly on the "make" of the main hne current — "break" and
"make" being the technical terms respectively for the opening and cloeing
of the circuit. A form of repeater intended to effect in a higa degree this
result, called from its inventor the Ghegan, is shown in theory in the dia-
gram, Fig. 4. The characteristic instrument is a transmitter havinj^ a
second armature-bearing lever placed above the first one in such a poeitK>n
that one electromagnet serves to work both; the upper armature lorms a
l»ck contact simultaneously with the oooiing of the transmitter, and it
inclines to preserve the contact at U' untu the regular k>cal drouit (dotted)
has been closed at the local points in relay E: the action is therefore qmck
or slow as occasion requires. As in the Milliken and Weinv-Philline, there
sre three pairs of circuits; the main lines (solid black); the local dreuits
Jdotted); and the Shunt circuits (dot and dash). When relay W open it
^
BEPBATEB8.
1043
htm Um trnature of transmitter T; through ita toncue and post ^_
• west wire which opeoa, relemamg the armature of reUy £, and openinc
Joeai pointf. At (be ame time upper armature U* flies aninst its bacE
itMt sod eompletei s shunt eireuit by^ which battery b holds transmitter
dosed; and tM wire passing through its tongue ana post is kept intact.
rerting to the position of the instruments in the diagram Jt he distant east
(apposed to hsTS opened his kev. This opens relay W, which opmis
ismitter T (both anaatures); the drop in the fewer armature oi>ens
west msin Ime, wbiob opens relay S and its local points; but, as just
'aioed, ths eirocdt of battery h is now complete through the dot and
t h'nes. 80 that tnuismitter T is held closea and the east Ime is kept
It by its tongue acauut the stop. When the distant west breaks, the
ttnrs ot reky S remains on its oack stop, and, on the first downward
» of ths uroer armature of transmitter T\ the local circuit of trans-
r 7^ is broken, and at its tongue and post the east line opens. The
Modsr, thus warned, closes his key; the sender at the distant west takes
ircuit; sad action siiular to that just described begins with relay £, and
« a IjJm ooorsa.
Weli^-JPiailipa Repeater*
leoretical disgram of the Weiny-Phillips repeater is given herewith.
1 general use by one of the prinoipal telegraph eompanies, and is
. ..J
HHH HI'IP
Fio. 6.
!iere because it involves the principle of differentiation in mag-
doh plays so important a i>art in duplex telegraphy. As in the
iTB are three distinct circuits in duplicate; and m the disgrams
rformixis like functions in the two types of repeaters are simi-
• The connections and functions of the main line (solid black)
^i JooaJ (dotted) circuits are identical with those of the Milli-
stead of the extra magnets and pendent armature of the latter,
buJsLT iron shell enclosing a straight iron core and its windings,
ion of shell and straight core performing the same functions
horse-rshoe core. The turns of wire around the core of the
stre eQually divided, and the current traverses the two halves
rectlons. Such a core is said to be differentially wound, be-
la enersia^ by the difference in strength of the currents in
when the coils are equal in resistance, the equal currents.
K>ait;e directions around the core, neutralize each other. If
s ia opened, the core at once becomes a magnet capable of
-nsbtiire at the moment when, the repeater in operation, the
key, opening relay E\ then transmitter T\ then
{
1044
TELEGRAPHY.
opening the "west" wire, which would open relay IT, timiiamitter 7*, aad
therefore the east wirej but the opening of tranemitter T* in prevented bi
the energisinfic at the cntioal moment of oore YF' ,oneooil of which is openeo
when transmitter T opens. When the distant west brei^ and senda. the
action begins with the west relay instead of the east, and foUoiva the
oourse.
Duplex JeleuM'ispliy.
That method of telegraphy by which meesages can be eent and leneited
over one wire at the same time is called duplex; and the system in genenl
use. known as the polar duplex, is illustrated in the aooompanvins diagfaao.
In single telegraphy all Dm relays in the circuit, including the nonke oina
respond to the movements of the key; the duplex system impliee a hone
relay and sounder unresponsive, but a distant rday r^gpaomye to the morve-
ments of the home key; and this result is effected by a differential arrang^'
ment of magnet ooils, of which the extra magnet coils in the WeinyoPhilfaps
repeater furnished an example. A current dividing between two eoili and
their connecting ?rirefl of equal resistance will divide equidly, aod imiwring
round the cores, Will produce no mapietio effect in them, lids oonditioa
is established when the resistanee of the wire marked -rrX-" in the diagram
WEST
EAST
THEORETICAL DIAGRAM OF POLAR DUPLEX
BALANCINO SWITCH OMITTEO
Fxo. 6.
fs balanced by the resistance of a set of adjustable ooOs In a rheostat marked
R. This is called the ohmie balance (from ohm, the unit of resistanoe); and
the static balance is effected by neutralising the static discharge on long
lines by means of an adjustable condenser C, and retardation ooil r, shunt-
ing the rheostat as shown. In the single line relay the movement of the
armature is effected by the help of a retractile spring in combination wHh
alternating conditions of current and no current on the line. In the polar
relay the spring is dispensed with, and the backward movement of the arm-
ature is effected, not by a spring, but by means of a current in a direction
opposite to that which determined the forward movement. This reversal
oi the direction of the current is effected by means of a pole-changer, PC,
whose lever, T, connected with the main and artificial lines, makes contact,
by means of a local circuit and key, /C, with the zinc ( — ) and copper (-f>)
terminal of a battery alternately. The usage in practice is sine to the nne
when the key is closed; copper, when open. The law for the produetion of
magnetic poles by a current is this: When a core is k>oked at "end on,*
^
REPEATERS. 1045
imnt pttsing round it in the direction of the hands of a clock produces
h-Mekiiu; matpefcinn, 8; in the opposite direction, north-seeking mag-
nOf marEed ft. A sprinf^less armatureu permanently masnetixed and
ted, BB shown in the drawing, will, if its tree end is placed between S and
agnetio poIeB, be moved in obedience to the well-known law that like
I repel, while unlike poles attract each other. The "east" and "west "
inal is each a duplicate of the other in every reqpMsct; and a description
e operation at one terminal will answer for both.
der the oonditione shown, the keys are open; and the batteries, which
the same JB.M.F.. oppose their copper (+ ) poles to each other, so that
Trent flows in the main line. But in the artificial line the current
round the core in such direction as. according to the rule just given,
(duoe N and S polarities as marked, opening the sounder circuits at
enninals. If, by means of key. K\ the pole-changer, PC', of "east "
I is closed, the connections of battery, B\ are changed: it is said to
ersed; and it now adds its £LM.F. to that of battery B, the current
; in a direction from "west" to "east"; Le., from copper to sine
e current in the main line is to that in the artificial as 2 to 1; and if
itive strength of the resultant magnetic poles is represented by smidl
r that produced b^ the current in the artificial line, and by large type
main, the magnetic conditions can be graphically shown, as they are
d on each side of the permanently magnetised armatures marked
! (ATO. In reUy. PR\ iiiaSn (JVO bN, causing it to remain open; in
? it has changed to At (N) n3 — just the reverse of that shown in
ram — the relay therefore closes, and the sounder also. If key, K.
est station is cloeed at the same time, the batteries are again plaoea
ition, but with sine (— ) poles to the line, insteftd of, as m the first
copper (+) poles. The result is no current on the main line; but
•nt m the artificial lines, flowing in the direction from the ground
otential is 0) to the zinc (— ) of the batteries, the magnetic condi-
east " station is represented bv n (AT') «, which closes relay, PR';
west " station by n (iV) «, which closes relay PR. The conditions
to duplex work, vis., tha^ the movement oi key, K% should have
)n relay, PR', but should operate the distant relay, PR, are thus
nd the transmasion of messages in opposite directions at the same
de praoticablew In the case of the Wheatstone Automatic duplex
age goes on at high rate of speed, the maximum rate being 250
inute.
ive already been traced out the magnetic poles formed in the
of the relay cores as the result of three possible combinations of
) copper to line at each end; (2) zinc at east, copper at west end;
(ne at each end.
r poflsible ^ combination remains to be traced out with reference
I formed; it is shown in Fig. 7, where the duplex b represented
ore near^ approaching that which obtains in practice. At the
shuTg end, nnc is to the line; at the east, or New Yprk end. it is
affect on the distant relay in each case is indicated m the draw*
9 mke of clearness the local ssrstems are omitted ; at each terminal
circuit is represented by a dotted line; the main line by solid
ays 'ndth their windings are shown in a manner fitted for tracir ~
effects. Representing the polarity of the armatures by (i
^ the magnetic condition of the cores in the manner aooptc
lug paragraph, it must be imderstood that the point of view
tireea tHe cores. The direction of the current on the main
atfram is from New York to Pittsburg. At the New York end
yf the current in the artificial line is from the battery to the
JPIttsbur^K end the current sets in from the ground to the zinc
tanoo. In the Pittsbure relay the magnetic conditions, begin*
Jowuut core, are Na (AT) nS; the laige letters are the poles
>ie TURin line current: the small are those resulting from the
artificial line whose direction is from ground to dynamo; the
a-vw upivard and the relay opens, as shown. In the New
» mayietic conditions Qower core first) are Nt iS) nS; the
.vm. clo'^m amd the local points closed.
of tli^ duplex are apparent on examination of the diagram.
fri^h disks on the top are rheostats; each contains a number
for making the resistance of the artificial line equal to that
(
1046
TELEGRAPHY.
of the main. Under the rheostata are the oondenaers for
e£Fectfl on the relay of the static dieoharge of the line. At the N
end is a chemical battery with the old style of pole changer; when
shown, it sends copper to the line, and puts sine to the ground; whMi
it puts sine to line and copper to ground. At the Pittsburg end
an entirely different arrangement; it is the one now almost uni
use. Two dynamos fumiah the current ; the jrasttive pole of one is
tte
c
^^
^
o
Fig. 7.
the other pole is led throu^^h a safety lamp to a cut-off switch, thence to the
pole changer which sends smo to the line when closed. Of the other dynamo
the negative pole U grounded: the copper current goes to the right-hand
post of the pole changer, which is very much simpler In form than the old
style. The Dalancing switches, omitted from Fig. 6, are shown marked A
and F: by means of these whoi the lever, say F, is thrown to the right, the
main line wire is detached from the pole changer and paanno through a
compensating resistance to the ground.
1
BEPEATEBS.
1047
Dnplex I<oop AystoHB.
For many years after the introduction of the duplex and quadruplex
8 number of lines operated by those systems was small; but with im-
orements in the material for wires and in line construction the number
tdually increased until now nearly one half the wim of the two leading
npaniee are utilised for one syst^ or the other; and of the wires thus
irated the working sets, to the extent of nearly one half, are assembled in
'h offices, and the wires themselves are worked, by what are called loops,
a branch offices located mostly in the different exehanees. The appara-
and connections by which the service of the duplex is extended to a
ich are therefore an essential part of multiplex telegraphy. Fig. 8 is a
ram of the duplex loop system; the places of polar relay, pole chanser
rheostat are indicatea; the main line connections shown in Fi^. 6 and 7
)nutted; and the local connections which are entirely omitted from
DUPLEX LOOP
Fio. 8.
lere inserted; 00 that Fiffs. 7 and 8 combined give a representa-
1 woridng duplex. The polar relay controls the local circuit,
>agii its points; the thumbscrews mark the Joining of the office
!iose of the instrument; the electromagnet of the pole changer is
V means of two keys whoee connecting wires jom those of the
ft at the thumbscrews. A sounder, a six-point switch^ a thre»-
two lamps, and a 23-voIt dynamo complete the outfit for the
The current is led first to the three-point switch where it
circuit, called the receiving side, may be traced (dotted line)
oints of the relay, through the soimder, to a lever in the six-
vhich, if turned to the n^ht, conducts the current through a
rround. The other circmt, called the sending side, may be
ine^ through, the magnet of the pole changer, through two
y a lever in the six-point switch which, turned to the right,
2Cts tiie current through a lamp to the ground. There are
rrounded circuits, with connections as described, the current
for zzuuiy like circuits is supplied by one dynamo. In the
1 are Bnnyvm other two pomts: to one, marked Af, is con-
rtendiu^ to a distant branch office, through a sounder there-
3 j^rouoa ; to the other point, marked iV, is connected a wire
led through a sounder and key, thence to the ground.
na oompleted, the levers of the six-point switch may be
^t to left: the use of the duplex is then extended to the
) polar relay works the sounden in both main and branch
{
1048
TELEGRAPHY.
office; the key in the branch controls the electromagnet of the pole cfaaa^
in the main office. The lamps A and B are in the main office local circuita.
and compensate severally for the resistance of the two esEtennons when Use
loop is cut out.
Half-Atkinson ]ftcp«iater.
The description of the duplex local (office and branch) ss^atem ,
the way for an interesting form of repeater by means of which the o —
a single wire of considerable length may repeat into, i.e., alternately .^
and receive on, a duplex wire or one side of a quadruplex. This ac>parmt
on
Fio. 0.
^
BEPEATER8. 1049
named by prefisnc the word "half" to whatarer form of single line re-
ater is used; e^., half-MiUilE«n, or hatf'-Ghenii. To present m many
ferent forms of repeaters as possible within the limits of this article, the
gnun (Fuf. 0) ibows a half-Atkinson. In the upper right-hand corner is
msented m akeletoD form the duplex local system Just described, to-
her with the jack in the loop switch for the placmg of the repeater wedge.
) apparatuf of the repeater is seen to be a transmitter in the lower left
ler, a oommon reby of 150 ohms resistance, two sounden, two ke/s.
pe,ana a amall dynamo. In the lower right comer is a jade to which
»ae n'de is oonaected the single line to distant points; on the other side
le main battery. With the wedge, as indicated, inserted in the jack, the
1 line drouit can be traced from the battery MB throui;h the post and
ue of the transmitter, through the key and magnet coils of the relay*
OS back to the jack and main line *'out."
addition to the main line dreuit there aie four others; two of them are
isions of the 23-volt system of the duplex; of these one has in circuit a
ihanger, Uunp, sounder, and the local points of the oommon relay, and
Dates in a ground; this arrangement places the pole changer in the
>J of the coDunon relay. The other circuit has witmn it the local points
polar reky, lamp, the electromagnet of the transmitter, and termi-
In a ground; this arrangement places the transmitter (and the single
hich passes through ita poet and tongue) in the control of the local
of the polar relay. Of the local circuits of the repeater proper, one
)d dot and dash) extends from one pole of a 7-volt dynamo through
rer post and lever of the transmitter, through the ooils of a repeat-
inder RS; thence back to the other pole of the dynamo: another
(dotted) runs through the lever and back stop of RS, making oon-
as shown, with the local points of the common relay. On the base
sla/ the connecting posts on the right join the ooils of the relay with
a Ime wires; the posts on the left connect with the local points of the
fVhen the transmitter is open the sounder RS is open: the lever
ontact on the back stop, and completes a circuit in which is the
agnet of the pole changer.
le all the circuits closed and ready for work. When a distant
the single line writes, he operates the relay through whose local
isees the pole changer circuit; he controls the pole changer and,
the relay at the distant end of the duplex. Wh«i the distant
the duplex writes, he operates the polar relay whose local points
e electromagnet of transmitter T, through whose tozigue and post
I single line. He thus controls every relay on the single line cir-
«8poiiae of the pole changer to his own sending ^which it is the
the repeater to avoid) is prevented by the bridging of the local
he oommon relay through the lever and back stop of RS. The
tion on the duplex may thus oommunicate with any office on the
and conversely.
>n of this repeater can be utilised to repeat from one single line
r; when so arranged it is known as the Atkinson repeater, wad
adard of one of the leading companies.
Il«i]ilex Itepeiater.
orked in the duplex or quadruplex system, the static capacity
rhich plays little if any part in the operation of circuits oy the
i, plaoee & limit on the length of the continuous circuit. But
betvreen vrorking stations can be greatly extended by the use
1 vrfaich, by an arrangement perfectly simple, the pole changer
rcuit is controlled by the relay points of the first. The long-
'Ouit in the United States is that worked between New York
CISCO, 'with six repeaters.
' tixc repeater in this and many other duplex circuits has been
tl&e recent introduction of the J. C. Barclay pole-changing
riata of a polar relay so constructed that two armatures, in-
»iii tlie otner. move on a common arbor^ one armature con-
circuite; to the other is attached the mam line which makes
It sumI back stop with the poles of the battery; it is thus a
pole obancer combined.
(
1050
TELEGRAPHY.
The operation of differential relays like M in the diasnun of the
plex, by alternations of "no battoy" and "battery,^ is the "^^
the Steams duplex, which, as the first oondenserHisin^, and therefore
eliminating duplex in the world, has a oertain histone intereoi. In J
ary, 1868. there were in use by the Franklin TelegrN>h Compstny a diipfeit|
set New York to Philadelphia, and another to Boston; and in Afloat. ISJL,
by the Western Union Telegraph Company, a duplex. New York to Albany
— all without condensers. In March, 1872, the Steams duplex, with eos-
denser, went into operation between New York and Chicago, out it has been
superseded by the polar system.
Reverting to the diagram, the pole changer with tta adjunota, and the
polar relay of the quadruplex, are omitted; one pole of the bsAtery i||
\
LAvMW-
WEST
fE^ fm
d'l'l'l'l#l'l"l'l'[+S° T^G
B
STEARNS DUPUEX
Fio. 10.
grounded, and the lever of transmitter, 7, is grounded through a _
equal to that of battery, B. This grounds the line through tongue, <» and
leaves the battery open at the post, P, The "east " station (not uiown ) is a
duplicate of the west," and the control of relay, D. by the distant trans-
mitter, 7*', may be traced as follows. Suppose distant transmitter, T*', sends
copper to the line when closed, the current dividii^ equally between the
main and artificial lines indistcmt relay, D\ has no effect upon it; but at the
west station there is no current in the artificial line in relay, I>, so Uwt
the current in the main line doses it. Open the key, K\ and the line is
grounded through the lever of transmitter, T*\ battery B* is open, and there
S-ound through the lever of open transmitter, 7^, to the^ sine pole of battery,
, is neutralised in relay. D, by an equal current flowing from the ground
through its artificial line in the opposite direction around its oorea, so
that relay, D, remains open. Now close distant transmitter, T**, and the
current in the artificial line (i.e., through the rheostat, R) of relay D is over-
powered as to its effects bv a current on the main line of twice its strength.
and relay D is cbsed. It is thus shown to be controlled by the distantkey.
K\ irrespective of the position of home key, K, and the conditiona neoeaaary
to duplex tel^raphy are met.
e4_
QUADRUPLJBX.
n of takacnpby alloin of two dm
Iho HiDe win, tad at the luu til
m duplsXM, BO diffemit in peine
V oomwiKioD u>T the purpoM d<Bis>u>t«d. If tl
a of the qiudiuphn is exuiiaed, there will be o
ilex, ao Ions u the working □
wurkiiis roinimuDi eon be doubled, I
BfKblfl difference 1o the polar relays. —
>h]', the opentioD ot the sinsle relay, fitted i
1052 TBLBORAPHT.
■pring, WM effeoted bv opening and clooing the key; T>r, tn other words, by
alternating periods of "no ottitAt" and cuerent" on the wire. It wm
further stated, in anticipation of its introduction at this point, that the
■pring ooiild be so adjusted that a weak current, thoqgb flowing all the time
tnrough the coils, would not close it. To effect the closinc an inrriaw
of battery, and therefore of current strength, is necessary, so that the relay.
instead of, as in the first instance, responding to alternating periods of "no
current" and " current "xiouki be operated by alternating perioda of "week
current" and "strong."
The diagram, Fig. 11. illustrating ihe theory of the quadruplex, will be
seen on examination to be a combination of the polar and Steams duplexes.
each of which has already been described. The^ operation of the Yearns
duplex in combination diners from that described in connection with Fig. 10.
only in that there is always on the wire a minimum of current sufficient to
operate the polar side of the quadruplex ; the neutral relays M and M\
iaeatical with that marked D in Fig. 10, are operated by alternating periotb
of "weak" current and "strong." after the mannw of the Steams. In
practice the weak current ia technically called the "short end"; the strong,
the "long end"; and the diagram shows how, with different methods of
current production, vis., the chemical battery and the dynamo, the pro*
portioning of the currrat in the ratio usually of 1 to 3 is effected, ilie
clock-face pole changer operates, as already described, to send when open
(see diagram) copper to line ana zinc to the ground; when closed, nnc to
the line and copper to the ground. If the connections of transmitter T
are traced it will be seen to admit to the pole changer one third of the battenr
when open, and the entire battery when closed; in other words, the move-
ments of the transmitter determine a "short" or "long" end to line. At
the left-hand terminal transmitter D effects a like result but by different
means. In connection with the transmitter are two sets of resistanoe ooib;
80 proportioned that when transmitter D is closed all the cturent from ths
djrnamo goes to line: when open, one third of it goes to the line and two
thirds is leaked " on to the ground. One pole of each dynamo is grounded;
the other is connected through a lamp to the pole changer in such a war
that the rule " zinc to the line when closed, copper whmi open " holds good.
The main line is shown in solid black; the artincial in dotted lines: the rheo-
stats and condensers with their retardation coils marked RC are identical in
principle with those shown in the polar duplex. In the diagram transmit-
ter D with its companion pole changer is closed; transmitter T wHh its
pole changer is open; the effect of these conditions is respectively to close
relays Af'and /C, and to open relays M and F\ the reasons for these results
have already been set forth in detail in connection with the polar and
Steams duplexes, so that it in not necessary to repeat them here. In short,
there is in the quadruplex a pair of polar relays which respond to changes
in the direcHon, not in the stren^h of the current; and a pair of neutral
relays, which respond to changes m the s(reni^, not in the direction of Uie
current. The diagram shows the apparatus m its simplest form; tlure are
a nimiber of details in oonnectksn with its operation, the complete eonnee-
tions for which are rather too complicated for this book. On page 190 of
Mavers's American Telegraphy wiWoe found a diagram embodymg the full
scheme of connections; and Thom and Jones' Telegraphic ConnecHonM con-
tains diagrams and detailed descriptions of the systems in general use.
Morse, used in the United States and Panada.
Conttnc«t«l« used in Europe and elsewhere.
Pkilllpa, used in the United States for "press" work.
Dash — 2 dots.
Long dash — 4 dots.
Space between elements of a letter * 1 dot.
Space between letters of a word >« 3 dota.
Interval in spaced letters ■" 2 dots.
Space between words ^ 3 dola.
TELEGRAPH CODES. 1053
A
B
G
D
£
F
G
U
I
J
K
L
M
N
0
P
s
T
U
V
IV
K
kr
5
t3h
311
a.
Mone. ContineniaL
a
MumertftU.
Mone. ContineniaL
^
- . . • .... — .
. ..
iiPiuictaifttfaii, Ate.
Morae, Continental.
'ins
k
1054
TELEGRAPHY.
Morw,
Contmtnial
J. I
Oapitatised letter
Colon followed I
by quotation: " |
o cents
. Decimal point
If Paragraph
Italics or undwUne
) Parentheses
Brackets )
" Quotation I
marks.
Quotation within)
a quotation J
Period
Colon
— Colon dash
Semicolon
, Comma
7 Interrogation
! Exclamation
Fraction line
— Dash
- Hyphen
' Apostrophe
£ Pound Sterling
/ Shilling mark
$ £>oIlar mark
d Pence
Capitalised letter
Colon followed by quo- \
tation: " )
o cents
. Decimal point
H Paragraph
Italics or underline
Parentheses
Brackets
Quotation marks
PhiUip:
Q ^
Quotation within a \
quotation""" J
▲bbr«vf atloaa Im Comhiob 17e«.
Mtn. Minute.
Maqr. Messenger.
Mak, Mistake.
No. Number.
Nta, Nothing.
N,M, No more.
O.K. All right.
Ofa, Office.
Opr. Operator.
8tg, Signature.
Pd. Pwd.
8 k. Quick.
J3.A. Give better address.
Bn. Been.
BaL Battery.
BbL Barrd.
CoL CoUeet.
Ck. Check.
Co. Company.
D.H. Free.
Ex. Ebcpress.
PrL Freight.
Fr. From.
O.A. Go ahead.
P.O. Post Office.
R.R. Repeat.
WIRELESS TELEGRAPHY.*
Revisbd by Fbsdbbick K. Vbbkland.
ooflequenoe of the rapid changes which the art of wireleee telegraphy
trgowg, it is impracticable to give here more than an outline of the
les involved, with descriptions of a few typical forms of apparatus,
ther details the reader is referred to the more complete works on the
«!«■• Ttflermphjr, as it is practiced to-day, is based upon the
t an electrieal oscillating system, when suitably proportioned, may
the source of electromagnetic waves, which radiate throufch space
it waves, and which have the power of exciting oscillations m a
>r on which they impinge.
M cal OsdllatloBa. — The essential elements of an oscillating
-e a capacity and an inductance, and means for charging the capacity
and allowing it to discharge through the in-
ductance. Fig. 1 represents such a system,
in which the capacity C may be a Leyden
jar, and the inductance L a coil of few turns
of coarse wire. A is a pair of knobs sepa-
rated by an air gap, and / an induction coil.
When the coil /is set in operation the jar C
is charged until its potential is sufficient to
break down the air gap O. When a spark
occurs, the air i;ap becomes a good conduc-
tor, and the jar discharges through the
inductance L.
If the ohmic resistance is not too high
the discharge is oscillatory, and the current
surges through the circuit with a frequency
N
1
2n?
«»
ux
or, if Ji is small.
Oecillatins Circuit
>y an Induetlon
^' 2nVLd'
I
AT » Frequency tn cycles per second.
£* " Inductance in henrys.
O » Capacity in farads.
H -• Resistance in ohms.
, iV becomea imaginary, and the discharge is undlreetlonaL
L;
C
r im vuBually very high; for example, if C — .005 microfarad
filienrv, — fi^cures which roughly represent the case cited, —
O cycles per second.
iB«#i« v^aavea. — Such a closed circuit oscillator may
urerful inductive effects, but it gives off little energy in
y l>e oon verted into a good radiator by separating the con-
.pacity, mo that the electrostatic field which lies between
ill ust rations for this chapter are taken from MaxweWt
9M Tel^ifra^ahVj^ by L^ Poincar<^ and Frederick K. Vreeland,
ay of tl&e AffcQraw Publishing Company.
1065
1056
WIRELESS TELEGRAPHY.
tbem may spread out into space instead of being concentrated in the
the iar.
Figure 2 shows an open drouit oscillator as used by Herts in the disoovery of
electromagnetic wares in space. Here the capacity between the q>heree &
and St, and the inductance of the short rod joining Uiem, are both small, ana
the frequency is correspondingly high, say 60,000,000 eyoles per eeoofid.
Fig. 2. Open Circuit "Dumb-bell" Oscillator, showing Electrostatic
Lines at the Moment Before the Air-gap Breaks Down.
The high frequency combined with the open eharaoter of the ciroait makes
this oscillator a good radiator. The dotted lines (Fig. 2) represent the
electrostatic field ^ust before the air gap breaks down. When the snark
occurs and the oscillations commence, these electrostatic lines shrink back
Fia. 3. Fidd surrounding a dumb-beO
osdUator when in operation. At the
moment illustrated the spheres are
discharging and the lines within the
large circle show the beginning of a half
wave about to be detached. Outside
the circle the preceding half wava is
started on its journey throu^
The oscillator
is shown, greatly ra-
duoed. within the small circle. (After
Herts.)
into the oscillator; but the shrinking is so sudden that portfons of them are
snapped off, as it were, forming closed loops (Fig. 3). which go off into spaoe
with the velocity of light (300.000 kilometera per second) expanding vwU-
cally as they go, and carrying energy with than. This is repeated in eaeh
hsSlf oscillation, until all the energy is radiated or wasted in internal '
INTBODUCmON.
1067
The nindly moving electrofltatic lines carry with them a magnetio field,
lOfe lines o? foroe form ooazial cirolm with centers in the axis of the oscil-
or, exptkodbg oooUnuously as npples expand about a pebble thrown into
) water. Their rajation to tlM electrostatic lines is shown in Fig. 4.
rhie oombioatioii of electrostatic and magnetic fields, traveling outward
h (he veioaty of light, constitutes an ewotromagnetic wave. When
b s wave encounters a
oooductlng obstacle it
les throtttb it without
rference, but if the ob*
le bea oonductorithe mag-
) h'oes eutting it induce
snts which absorb energy
the wave. If the o&>
9 be large, such as asheet
letai, the wave is oonar-
y out off aiKl reflected
tm a mirror; if theob-
beawire panallel to the
f the oscillator, it b^
the seat of secondary
iions, like those in the
or. but weaker. Any
lent capable of defeeet-
ee oscilbtioiis may be
us the receiver of a
telegraph system, of
the oscillator is the
tter.
Antenaia. — The
( oscillator shown in
Fi«. 4. A Portion of the Spherical Wave-
front proceeding from an Oscillator. The
Full Lines Indicate the Biagnetic Foroe,
the Broken Lines the Electric Force. The
Direction of Propagation is Perpendicular
, . to Both of these, and is therefore Radial,
operative only over
tanoee. The energy of the waves is limited by the small capacity
iciUator, and waves of such high frequency are readily absorbed
oies. In actual practice the oscillator takes the form of a
are or antenna, supported by a mast, and grounded at the lower
fh a spark gap (Fig. 5).
(
}
.B
TVansmitter with
»le AnteniiA.
Fia. 6. Receiver with Simple
Antenna and Coherer.
v&leot to luklf of a Hertsian oscillator, the lower half being
»plAced by the earth. The capacity and inductance are dis-
Jie wliole leni^h of the wire, and the law of their distribution
kve-leosth is four times the height of the antenna. Thus
WIRBLBBS TBLEQRAPHT.
trtNiiieney - velodty * mve-leLgth. would b« ^^'^"^ - 1,500.000
ordra per Hoond.
A Irse Bcrlium ouillfttor emiU irea Hartnui mvog. vhioh tr»Tel throuA
nace IUm UghC. A sTonitdcd oaailkMt bIvm oB Brouaded mvcs (FIi. 71.
They ue hkU warea, irhow electroiUtu Unsi, Lnstwl of bdnii ■Blt~ela*td.
Mrmln&t* in tb« garth, to wblfb Oary
m inacfiarBblv bouod. Inrtcad of
traveJioiiaiwania nraight lines, tlicy
miut IoUdw tha mntour ol the a»-
ductinj lurhce ots- wUeb thay ahdi.
and BO thay may croag mauDtaini or
traval about tba aartb.
In Elidiiit over the eoDdueCiac aai^
faee m theearthtfaayBraaooompaniad
by altamaliBs oiutsita to Um surfaeg.
tlieae oorrents im*t« OHrcy Id dv»-
, aurfuH, with tha nault t, i, ,,
' the ia(«isitv of the wavea. Forthia
Fig. 7. Propaaation of GrouDded naaon the pnpafstiDH ■ muoh bwui
ftjTved Suiiaoe. dry or f roieo uoundwhoee n
ses.
of fiigjLblj in the day ai
a i^rouodcd reectver !• naad (Flf, 0>. llui
wnh « detaator C, aoDiMMed in langa mar
d A a relay or Ulcphoaio reoiiTar.
he beat known detaeton of eleetricKl oadl-
enr. A typical (arm ia ihown in Ftc. S. T ii a ^am
I two tightly fittinc ailvar plucg. B and £'. attaehoa lo
The eodj of the phiga axe about .6 ndUimetO' apart.
la another veni(«L anMnna A, wnh «
the ground- 5 is a battery and R a r — ^ _ ^ .»-
Tke Cfrfe*r«r. — One of the beat known detaeton of eleetrinl oadl-
latlons is the mhertr. .~-_.
Fio. 8. Coberet — Loncitudhial Croaa Beetioii.
and the niac* between them oontatna a mixture of aitvir and nicke)
filing!, with sumetimn a traee of mercury. The tube ia then exhauMed
and aealed.
NormaUy. the fitinga lie looaely together, and pnaent a high reaialance.
Tha coherer is practKally open circuited, but under the inSuoice of tba
electrical oscillAtiana the filings cohere, and the reiiitance Calli at once to a
few hundred ohma. If the coherer be connected in circuit with a battary
and a sensitive reiay CFif. 0), this drop (n reaiatance will opfnte the relay
and live a signal.
The filings continue to cohere after the oceaation nf the impulae that
affected them, but they may be aepanted by a mechanic shock. Or-
dinATily an automatic tapper ia arr^i£ed tc -'^'" '^^ *_i.- — i. **.-
relay fpVEa a aigaal. and ao reatore it to its sc
BYffTONIC SIONALINa.
1059
±^B
^^!ij^
9. ArrsDgwnent of Coharer C with Bmttecy B and Relay R
Recording Instrument, and T an Automatic Tapper.
/ is a
mple grounded antenne has a definite natural period of vibration,
tendency to adhere to this period is weak, and it may execute forced
jDB orer a wide range of trequenciee. Thus a given receiving an-
rtli respond to the radiations of various sending antenna, with only
preference for radiations whose period is the same as its own. Such
nna constitutes a simple "responsive" system, which is adapted to
shipboard or between ships and shore, where it is desirable that
ion may communicate with any other station fn. the vicinity,
a number of stations are so close together as to interfere with
sr, a responsive aystma is not suitable, but the apparatus must be
eotive, eo that any given pair of stations may mteroommunicate
(nterferenoe from the others. The most usual way of securing
r ia by Bpplying the principle of Electrical Resonance or Syntony.
Etrioal oecillating drcuit may be so oopstructed as to maJce it a
tor, i.e., the Dositiveness of its vibration p«iod may be greatly
so that it will remwnd readily to vibrations having its own nat-
i but will be little affected by impulses of a different period: just
led string win respond to a sound to which it is tuned, but not to
lifferen t pitch.
■ilT* — The criterion of sharp resonance is a persistent oscillation in
litter and receiver. In the transmitter there is a certain initial
lergy stored in the antenna or other charged condenser, and this
aduaily expended in radiation or in resistance of the conductors
e&p and other internal losses. The rate at which the stored
rpended determines the "damping" or rate of decay of the
In the reoeiver, energy is recdved by the antenna and consumed
fkU trork In the detector, or wasted in ohmic and other losses.
lai^e resonjant accumulation of energy, all these jos"^ should
o a minimum. In other words, the damping of both trans-
Kseiver must be smalL A simple antenna is a poor oscillator
^ersv ie radiated rapidly, and tne amplitude of its oscillations
a oorreeponding rate. The curve (Fig. 10) represents the
»ed oscilUktion ofa dumb-bell oscillator (Fig. 2) as determined
Tbe amplitude falls to ^ of its initial value after nine osoll-
oscillation of a simple grounded antenna may decay even
Ttlll, and this is why sharp resonance is Impossible between
le oBcillatin^ systems.
(
WIRELESS TELEOSAPHT.
Of dnuii (Fig. n Duy ba nuda quite t, peniBMnt vi-
ly u Ion in radiktioa, tad tb« ■<-mi-tn, o( the Mall»-
Fw. 10. DiMhaii* Cnrr* of Dumb-bell OnBator.
tiooa la dna nolnly to the abmio rcabtanos of tha aircuic.
aueh ■ lytMm ia rapraMOtcd by tha aguaUoa
.-\/A-/
R being tha resigtance in ohnu (or Id abaoluta luita).
L bains the iniiuctuin in hennia (or In ■baolute unita).
C bnnc the capacity in Israds (or in ahaotule units).
*nn expnagioa cot (t' + »> datenninea the frequency o( ■'
It — ^^ ^ Mid ia repraaantad by K rimiila hannuoiD eun
determinae the dlampina. and ia rapreaanted by tha lo(arithniie ei
indDliadliuBiDrig-lO.
For I — T, a mmplele pariod, the eipoDaotial term beooma
irtiloh ia tlia ntb of any ti
^
8TNTONIC SIQNAUNQ.
1061
ieeranent fa ddiiMd m the iMpurithm of the ratio of ttro cbniwntiTB Htn^
ng poinit, ud heDM hu halfthe aboTe value.)
lo i perauteat Tibntor of high frequency the ratio — ie imaU, and the
lUition may be writUn,
|.g£-^<eofyi;
^Ai
,.g6""«^ eoeV^^-,^.^
fhis form is more oonvenient than the oomplete equation, and ia
Seiently soourete for praetical purpoees.
ilfln JMrect.~Tbe value of A M here uoed is quite different from
reBwtanoe m measured by ordinary methodB, owing to the faet that
I rapidly oecilktiog ourrante are confined to a thin auperfioial layer on
ouUide of the oonduotor. The thiokneee in centimetere of the skin
nired to the point where the current dennty b — of ita value at the
oe,ii,
S
▼ 4w
*t^N*
where 9 «■ specific resistance of conductor,
M 1^ permeability of conductor,
N ■■ frequency of oscillation,
le eifeotive resistance of the skin is equivalent to the
nuous current of a shell whose thickness is.
for
^-^.-v^
Sw*iiN
topper 9 mt 1600 C. G. 8. units, and m = 1. If the frequency be
0 ^ per seoond the effective thickness 8' of the equivalent shell will
1 om. or about .001 inch.
A
at
with
Circuit
Fio. 12. Closed Oscillatang
Circuit Coupled to Antenna
Through a Transformer.
1062
WIRELESS TELEGRAPHY.
M/fmtom^e AppAvatvik — Two eloted dreuH oMillAton nuy eadiibil
▼er^ sharp resonance — a slight variation in tlie capacity or the induetanee
of either circuit will throw them out of tune — biit they cannot affect each
other at any great distance owing to their poor radiating and aboorfaing
powers. To make them available for signaling, they are oou|>led, each to
an antenna. The coupling may be effected by a direct eleotrieal oonnection
across an inductance coil or auto-tramrformer as in Fig. 11, or through an
air-core transformer PS (Fig. 12). Such a compound oeoillating •ya(«Bi
combines the virtues of its two component parts. The closed oarillating
circuit stores energy in its large-capacity condenser to maintain the osctUa-
lion, and this enernr is fed out slowly
to the antenna, which radiates H into
apace. In the receiver, the process li
reversed: the antenna absorbs energy
from the passing wave train and com-
municatee it to the elosed resonant
circuit, which is tuned to respoiMl to
impulses of the desired frequency.
To obtain the best results in both
transmitter and receiver, the cloeed cir-
cuits should be tuned to the
natural frequency as their
antenna circuits. For this purpose a
variable inductance L (Fig. 13) is often
placed in the antenna circuit, aikd thus
a given receiver or transmitter may be
FiQ. 18. Inductively Coupled ^^^ *<> ^y*if*^»S^ frequenciee. ine-
Transmitter with Tuning CoU in «P«ct» ve of the height of the antenna.
Antenna (Srouit.
TatJLTtmMETTMWiB.
The simple antenna system of Fi^. 5 and 6 has been almost enUrel^
superseded by the oompound oscillating system, even where selectivity, is
not important, because of tiie far greater intensity of radiation that may
be obtamed with the compound oscillator. With the nm]rie antenna tlw
energy of a wave train, such as that illustrated in Fig. 10, consists entirelv
of the energy which is stored up in the antenna at the moment the spark
occurs. Tnis energy deoends upon the capacity of the antenna and the
potential to which it is charged. As the voltage that may be suceessivebr
used is limited and the capacity of an antenna is comparatively small,
the enen|y oi the wave train is not sufficient to carry it over a long di»-
tance. Where a oompound oscillator is used, however, the condensers may
have a capacity many times as great as that of the antenna, and the po
of the apparatus is greatly increased. ....
A typical form of transmitter with oompound oscillating cirouit is shown
in Fig. 13, when / is an induction coil controlled by a senaing key and dia-
charSng across a spark-gap B. CPB is a dosed oscillating circuit com-
prising a battery of Leyaen jars C and the primary P of
transtormer, whose secondary S is
connected to the antenna A and to
ground. Both primary and second-
ary of this transformer consist of a
few turns of stout copper wire, or
cable, and the whole is immersed in a
vessa of oil. L is an additional in-
ductance coil, whose number of turns
may be varied, inserted in the
antenna circuit to facilitate tuning.
By varying this inductance and the
capacity ox the condenser C the two
X
c
eircuiU may be tuned in unison with . . __ .^. -al . n a _i_
each other and with the receivinc Fio. 14. Tnoumtter with A. C. Supply.
"*fiS»»Si«l««e»» wltfc A. C. Jhtpply.— A.more. powMful f otm o(
tnuumitter U afaown in Vig. 14. Here the power is detiTed from an A. <*
TRANSMITTERS.
1063
loenlor D wbkAi feeds an ordinary A. C. transformer T wound for a seoond-
kfy voltage of about 20.000 volts and immersed in oil. This takes the plaee
i the induction ooil of Fig. 13 for feeding the osoiUating oirouit QCOC. The
ecillating oirouit is ooupled to the antenna through a single coil L having
idjufltable terminals, which performs the double function of auto-trans-
ormer and tuning oou. It thus serves the same purpose as the toansformer
"^8 and the inductance L of Fig. 13.
If the alternator were directly eoupled to the transformer shunted by a
park-gap the apparatus would not operate satisfactorily owing to its tend-
ncy to form a not, low-frequency arc across the gap. As long as this arc
ontinued it would be impossible to charge the condensers to a sufficient
oltage to excite oscillations. To prevent this arcing a lam adjustable
sUf-induotion L. is inserted in the primary circuit of the tranistormer. This
hokfls down any sudden rush of current when the air-gap breaks down
y/y/////
Fio. 15. High-power Transmitter.
nd allows the arc to extinguish itself so that the condensers may be
barbed anew. When the apparatus is suitably adjusted it is possible to
btain several sparks to each alternation of the supply current.
IBI«>li*pow«r Trananstttera. — Where very intense radiation ii
iquired, as in transatlantic work, still more powerful apparatus is used,
iich as that shown in Fig. 15. The source of power does not directly
KMte the active oscillatini^ circuit, but is used to set up low-frequency
■cillations in a primary oscillating drcuitf which acts as a secondary aonrot
t power at hign voltage to supply the active circuit. D ia an A. C.
snerator whose voltage is stepped up to, say, 20,000 volts by the trana-
irmer To. A is a rotating arm geared to the shaft of the generator, and
aseing within sparking distance of two metallic sectors, Bo, Bx, When
le arm comes opposite the first sector, Bo. a spark leaps across and ehanci
Large condenser, Cf When the arm reaches the second sector, B|, thit
>ndeneer is discharged through the primary, P,, of an air-core transformer,
s. OscillaAions are set up in the primary oeeillating circuit CxBxPx, but
My Are of comparatively k>w frequency, owing to the laive capacity and
kductanoe of the circuit. They are stepped up to a very high voltage by
le transformer, T], and serve to charge the smaller condenser, C%, of the
3iiTe oscillating circuit, CfiP^ This condenser discharges across the
k-gap (?, and sets up a new series of oscillations, of the same high fre-
iieacy as that of the antenna circuit, A8%, to which the circuit C^fiPt
ooupled by a second air-core transformer, T9. The huse condenser, C* . is
lus cnarged at a moderate voltMe, and its energy is raoiated at a stiitable
orkin^ mouency, which woukTbe impractieaDie if the condenser were
mply mduaed in the working circuit in the usual way.
Vni«snsltterB« — The distinctive feature of this system
1064
WIRELESS TELEaRAPHT.
1
ia the fact that th« antenna is not grounded (Fig. 16), but is oonneeied tea
capacity area K. This is made in the form of a metal cylinder with rounded
}S
p§ is
<^^rx/n^y/r^^^
Fio. 16. Transmitter with Artificial Ground.
ends, made in two parts which telescope one over'the other, so that its
ity may be varied. It forms with the earth a condenser, whidh "^^
purpose of a ground connection.
ths
The principles which govern the design of a syntonic receiver are sbnilar
to those which obtain m the case of the transmitter, but their practical
application is somewhat different. In the transmitter a considerable sim-
ply of energy is stored in a charged condenser, and this energy takes tut
form of powerful oscillating currents in the transmitter circuits. These
currents are surprisingly heavy — an induction coil fed bv a few oells
of storaip battery may generate currents of several himdred amperes,
representmg an activity of many horse-povrer. To carry such currents
emcientlv heavy conductors are required, and circuits of large capacity and
small inductance are desirable in order that the requisite energy may be
handled at practicable voltages. In the receiver, howevu-, the amoimt of
energy received from the incoming waves is exceedingly small, and the
currents induced are correspondixigly feeble. Where a conerer — a
potential-operated device — is used^ for detecting the oscillations, the
voltage applied at its terminals should be made as large as possible. Henee
the osoiliating circuits are made with small capacity and large inductance,
and their ohmic resistance may be quite large without seriously increasfaig
the damping of the oscillations. (See Fig. l7.)
But where the sluupest selectivity is required it is of the utmoet lmport>
anee to make the resistance as small as possible so as to diminish the
damping, for a strongly damped receiver circuit is not only incapable of
sharp resonance, but It requires a close eoupllnff to the antenna cfreult to
secure the necessary stren^h of signals. The sharpest resonance is secured
with a loosely coupled system, for there the oscillating circuit is eampar»>
tively free from the disturbing influence of the strongly damped antenna
circuit; but loose coupling diminishes the intensity of the aecondary
oscillations, and requires a strongly resonant osoiliating circuit to give
readable signals. Xfsually a compromise is required, and the cloeeness of
coupling Is made adjustable by varying the distance between the primary
and secondary colls, so that loose coupling may be used when the shaxpest
selectivity is required, or stronger signals may be secured by bringing the
coils in cuMcr inductive relation.
C«k«r«r IKccetrer witli ^IcMr. -* This rscdver CFig. 17) is
denigned to give a high voltage at the coherer terminals. A is the receiving
antenna, which is grounded through an inductance L and the primary Ju
of a transformer of special construction, which is called a " jigger. " /, is
RECEIVERS.
1065
tbe seoondsry of this transformer, to whoae outer temdnalB the coherer T
b oonneoted. The secondary ooil J*\b broken in the middle and the inner
terminals thus formed are connected to a condenser C, and also to the
relay and recording apparatus.
The peculiar construction of the jigger is shown in Fig. 17, which repre-
sents hiuf of the coil in longitudinal cross section. / is a glass tube on wnich
is wound a single layer jt of primary winding.^ /s /s are the two halves of
the secondary winding, which is represented diagrammatically, each of the
sigssg lines on the aiagram representing a layer of winding. The imier
iaytfnas the greatest number of turns, and the number of turns decreases in
the suooesBive layers to the last, which has only two or three turns. ;s is
the eondenser, from which wires lead out to the relay and auxiliary apparar
fto. 17. Coherer Receiver
with Jigger.
Fxa. 18. Method of Winding
Jigger.
,us. The secondary winding has a large number of turns of fine wire, and
ta distributed capacity and mductanoe are such that it has a natural period
>f vibration, when connected to the coherer, equal to that of the antenna
circuit and of the incoming waves. It is thus, to a certain extent, syntonic
n its action, and it has the further advantage of stepping-up thr voltage
»f the receiver oscillations and thus increasing their effect on the coherer.
IkS the capacity of a coherer is a rather uncertain and variable quantity, a
ondenser C« is sometimes shunted across its terminals to make tne appaira-
us more dennitely selective.
Aec«lv«r with IiOw-r«alat»»ce ]>«t«ctor. — The peculiar ar-
angement of tbe last-described receiver is due to the practically open-clr*
ult character of the coherer. When low-resistance detectors are used they
lay be inserted in series in a simple resonant circuit as shown in Fig. 19.
f ui an air-core transformer whose primary coil is connected in series with
he antenna. A, The secondary is connected in a closed oscillating circuit
icluding the condenser C, which is preferably adjustable for purposes of
anlng, the detector D and sometimes an additional inductance coil L.
lie transformer if is preferably a loosely coupled one,
s the low-resistance character of the oscillating dr-
oit permits comparatively strong resonant currents
> be induced by a feeble electromotive force. The
>ilB are usually mounted so that the distance between
lem may be varied, to adjust the coefficient of coup-
Receiver wltli Shomted Detector.— Another
'rangement, which permits a high degree of selectiv-
y while not requiring a detector of especially low
8i8tance,is shown in Fig. 20. Here the oecillatinff
re alt SC is closed upon Itself and the detector D
shunted across the condenser. This arrangement
ay be adapted to detectors of widely varving charac-
rfatlcs; thus, if the detector is one whroh requires
high voltage to operate it, the condenser C is made
small capacity and the inductance is made corre-
ondingly large. If, on the other hand, the detector has comparatively
w reautanoe, the oscillating circuit Is made of large capacity and low
Fio. 19. Receiver
circuits with De-
tector in series.
K
1066
WIRELESS TELEORAPHT.
rMistance, ao that it may be robbed of ooaslderable current withoot
greatly increasing the damping. The particular detector shown in the
figure is the electrolytic (" polanphone *') cell described below. ^ ia a kical -
battery and F is a potentiometer for adjustins the voltage implied to the
ceil. C ia A larse condenser which permits the flow of the osoiUaton t9
the detector wmle prereuting the short-cirooiting of the battery throngk
the coil S.
I ^B
JLMtl- umA Ante-Colierera. — Besides the typical filings
above described, many other forms of coherer have been devised. Some owe
their distinctive characteristics to the material of which they are made.
For instance, if carbon grains be used instead of metallic filinss the operation
of the coherer is reversed, i.e., the apparatus is normally a fairly good conduc-
tor, but on the receipt of a aiigal
its conductivity is destroyed. De-
tectors of this type are oalled anti-
cohtren. Hie De Forest "Respoo-
der " acts in a similar manner. Two
electrodes of tin or other suitable
metal are immersed, close toseiher.
in a poorly conductiog liquio, such
X*" yT~V*"-fHg I as glycerine eontaining a trace of
^ ^ p I water, in which are suspended
• minute particles of metaL Under
the influence of a local battery
these particles form conductii^
bridges or "trees" reaching across
between the two eteetrodes. and
eompleting the circuit through the battenr and a telephone. When oscilla-
tions are iiassed through the apparatus the bridges are disrupted, the con-
ductivity is destroved, and a sound is produced in the telephone.
Other modifications have for their object the abolition of the tapper,
and give rise to the class of auto-coheren^ whose action is entirely autommtie.
A globule of mercury in light contact with electrodes of iron or carbon eon*
stitutes an effective form of this device.
Various mineral substances also have been found to be more or less
effective as detectors of hlgh-freanency oscillations. For example, if a
crystal or fragment of carborunaum magnetite or metallic silicon be
clamped between a pair of metallic ternunals its resistance is altered
when the oscillations are caused to pass through it. When properly con-
structed such detectors are quite sensitive.
An improved form of mercury auto-coherer is shoit'n in Fig. 21. A disk
of steel a rotates in light contact with a globule of mercury 6 contained in a
FlQ.
20. Receiver Circuits
Shunted Detector.
with
^y>JvW>^tf
— T'-T
— — .._...«. - ^-K -
PLAN
Fio. 21. Meroury Anto-Obherer.
oup d, wUoh eonstitutes one terminal of the apparatus. The spring s,
bearing on the shaft / which carries the disk a. constitutes the other tei^
minal. The disk a is normally separated from the mercury by a thin film
DETECrOSS.
•Md thrau(di
itltnnariy Itteh
beplaoMl Id
, ..._ -^ b^Dd tha
jt th* byitovd*. or "nugnftlo Irtetfam."
But If ■ nj^dly oacUlntlna cumut ba puaed tbrouah &
il KurrouiidiD^ the iron, the hystweris is reduced and a Buddcn ehaose in
a niajraetisAtion accun. Thia ahanae In madnetiiAtloD
ty be ouiasl to Induoe aa E.M.F. in a aeo^ coil >ui-
iiodioy the oon, and thua op«Ma • talaphone ntmvtt in
Fis. 32 ibomonatDnaof thaM>P"*t<i>- Wlaaatnuided
It of Gna inn wicea paaaiua om the puUeyi /"i". whiah
I diiran by oloekworlc MW are permanent iaa«Deta
iob Bupcdy tba Aald to ioduoe a aoptinuDUBly varyinc
■DMIaMioQ Sa thamoving aire W. A iaaooil of supper
a IhrouEh whicb the oaoillatioiiB are paaaed, eaeiraluig
oara W, and £ ia » aeoaod soil ia iruah aurnBta an
oaed toopantta thatalaptwne T.
Blec*ral7tl« ItoMaton. — Another doteetoc, which
ixtramely aeiuicive. dapanda kur Ita oparatkon on tha
1 ia polariiatioD of a apeeiaUy cDDatnieted eieotrolytla
'-■ -' ' 'lUitloa. *- ^■
Che metal.
whioh a
i
i by oaoilbitlaiu
iSSlflmi
thraiuh it.
._ , atariaTaliDh
ilatlnuin, and a lari«r cuboda, Immaraad in a auitabba
Lrolyta. Wbea inota a cell Is ooaneoted aoroH • source
-M.F. ^raMer than tha daeoniDoaltion E.U.F. of the cell.
rraitvil] flovandUia cell wiUbeiniaapolBriMd.oppDnng
•untar ELU.F. to tba puoc* of the eunwt. If the
-F.BeroaatheoeUbaao adiuatad that the cell ia polariied
>* proper critical l>olnt. It bwomn remarkably HnuitiTe
KtarDBl impulaea. The oacdllatlonB from an ant«nna ^
Ins tliroua|fa It ha*< tha affeet of partially or eompletely
lariaiiig tha minota anode, and a taice momentary in- Fio. 23.
>a in the local corrent ooean, with tha elTect df repolar- Electrotytle
thsaelltolti aaoaitive point, ready for the next impulse. Detector —
a sbaona Id the local eutrent are lued in nperate a tek- Croai Section.
BDn-veolent fbrm of the cell b ibown in Fig. 23, and the connectloiu nt
att«ry, ato., an abown io S^. 30. T in a alaaB tube contalninc th«
1068 WIRELESS TELEGRAPHY.
eleetrohrie, C ii the esthode of stout platinum wire, and A is tht miaaftl
anode, both sealed by fusioa into the glass. The anode is a fine platimM
wire, .001 ineh diameter or even less, sealed into the oaiMllary tip of a amsB
class tube and then ground down flush with the surface of the naee, leading
only the end exposed. The area of anode surface is thus of the order of a
millionth of a square inch. In the oonneotion diagiam (Fig. 90) l> m ths
deteotor proper, F an adjustable inductive resistanoe or potaotiometer, te
regulate the voltage, and T a telephone.
IS«i-Filaai«mt Detectora. — Another type of detector owes ia
ezistenoe to the peculiar properties of an incandescent body when placed
in a rarifled gas. Under such conditions the incandescent body emits nmi
tirely charged corpuscles or electrons, which are free to move about In tM
rarifled gas, thus rendering it a more or less good conductor. If, for ex-
ample, an incandescent lamp filament be mounted in its exhausted bulb io
close proximity to a plate of metal connected to a third terminal, and a
battery be connected between this terminal and one of the torminala of the
filament, a current will flow from the
battoiy through the gas. If now
electrical osciluttions be eauaed to pass
. through the tube between the filament
1^ and insulated plate, the eondnetivity
QL^ of the tube is altered and Tariations
1 4 of the current from the battery oeenr
•^ . mil imimim illim ##% #l«ik ~-— — — ^•^■m bV_
•=-^/ corresponding to the preaenoe or
senoe of the oscUlationa. fig.
■hows a hot^lament detector 2>,
neeted acroas the condenser C of a
closed oscillating circuit SCC\ which
in turn is coupled to the *T»fc«*w^*M ^
'p*^"" throtigh a transformer PS. The &]*•
p.« i>A w^ vfiamonf n*4>«M«<^.. mcut of the deteotor is heated by a
Fio. 24. Hot-FIlament Deteotor. battery B and the local receiver cirtjiit,
including a second battery B* and a tolepnone receiver T, la connected
between the insulated plate IT and the positive terminal of tne filanient.
17«danBp«« OscilliittoM.
It has been pointed out above that a prime requisite of a seleeCive sic>
naling system is a transmitter whose oscillations are not strongly daznpeo.
An ideal transmitter for this purpose Is one In which the oeclTlatlona are
absolutely undamped ; that is, they are hlgh-fk«qneney alternating currents
of constant intensity. Such a transmitter, besides making poealble the
highest degree of selectivity, possesses other advantages: for example, the
continuous character of the oscillations enables a given amount of energy
to be transmitted at a very much lees intensity than is required wiHi a
strongly damped oscillator, which emits verv intense radiations for a brief
space of time, with long Intervals of inactivity when no enerrv la radiated
at all. Furthermore, the radiation from an undamped oeoUlator, betng
continuous, may be stored up cumulatively in the receiver, ao that a
siirnal of very feeble intensity maintained for a oomparatlvely long tfane
will have a relatively powerful effect on the receiver.
All these and other considerations point to the undamped oaeiUalor as
an importent factor in the future of wireless telegrM»hy. Already such
oscillators have been produced and applied to practieai work, but it Is
Impracticable in this section to discuss them in detalL
TELEPHONY.
Rktwbd bt J. I/LOTO Watnb, 3d.
Tn eleetrie speakiiiK telephone waa invented by Alexander Graham Bell
then of Boston) in 1876. While exciting great interest in soientific ae wdl
M popularordeB, it bade fair to be little more than a scientific toy untU the
tLteroommvnicating or exchan^se idea was brought forward. It is in this
oanection that the telephone is of primary importance to-day, the nmnber
a use rwuiinc well into the millions.
IVord Telepii*B«. — At first a single insUimient of
lell's type at each end of the line served aU purposes. Now oonmiercial
slepfaony has rendered it necessary to universally associate with these
iriBary instruments several other pieces of apparatus, and the scope of the
Hocd telephone has been broadened to indude all this allied apparatus of
lie telephone or subscriber's set.
Keq«lr«aieata for Op«rtatiom. — The fundamental problem
F the telephone is really more one of acoustics than of dectridty, and be-
muse of this all attempts to solve the problem failed until it was approached
■om a purely acoustic standpoint. In order to understand the reauire-
lents of operation it is necessary to understand the nature of sound and
;>eech.
Sound is propagated by means of vibrations of a purely physical naturei
le vibrations of the various partides of the sounding body being so timed
Fio. 1. Phonogram of the Word " Hdlo."
it there results a progressive wave motion. It is such a wave motion
(Hxiging upon the ear-drum and forcing it into a sympathetic vibration
.t ia reeogniaed as sound. Sound has three fundamental properties, —
dneas, pitch, and timbre or quality. Loudness depends upon the energy
the vibrations, pitch depends upon the rate of vibration — thus, the
rations per second — while quahty depends upon the kind of vibration
individual partides are performing.
F the character of the vibrations is such that the wave follows a simple
) law. a fine tone is produced. Every other kind of sound is produced
a wave more complicated than that of a pure tone. Eaeh source of
ad produces a wave form oharacteristio of that sound. Sounds vary in
lity from the pure tone to the most discordant noises, but there is no
srally reoo^ised point of transition from one to the other,
peech consists of a proper combination of many sorts of sounds varying
1 pure tones to mere noises and hisses, intermingled in a proper order,
each given a proper relative pitch.
he requirements for operation of the telephone are that any series of
idfl spoken at one end of a line shaU be transmitted to the other end
there siven out correct in relative pitch and in quality. The term
^ve piteh is used, as a corresponding change in the pitdi of all sounds
no distorting effect more than the difference between a low-pitched
1060
(
TELEPHONY.
knd hich-ititctiad Toios. Loudncaa ii ■lao of liltls nv
Iww tbs resaiw in nifficiait Tolume to b« hcBrd.
««•>■ sf XiBBUilMlMk — With tlie daoti
noQ u aooomplinhed by dmui* of deotrio oumnt ^
nmduotiiis lino from the nBtion at odb end to thftt _ _ . ... __
pwfeot trkDUDiwoD nich elMtrio w*ya an aiwet aquirmleiita, axtniit b
__.r nf ih> tound nvai producius them, the etnoatb of tlw •lactik
It each inctuit dinct ration to the sound Tibratioiu. Tilt
it the oth» ondTPuf
periodidly oTthe ei
pit<di of the Bound, while the auoceeding iDstuiUnc
eurrenl muit be auch that iba quality factor of the i
pictured electrically. From thiB it will ha avident
t«Dt ii a vibratory or alternating cun
Thifl muBt be con tinuallv borne m mJ
tora to be contended with in telepbonf
alteniatinc curreota, of power macnitudea, and
upon theiubject of telepho"- •——"!--!'". ■- "-
remeJy oomplei ch&ractw.
of the moet flvaential Eao-
H the foUowin
fl. Call Kadloc apparal
The daaJKii and tunctiq
(oh. or > band awltch.
>f these dementi dillar maierially for diOemt
vecmny naed, it beii«
t atari. Hthw itnuaht or U-«haped. ao mounted aa ta exert a polaf~
luenoe upon an eleatromasnet. before the polee of whiob latter
liaphraitm is iDouateil. For eonveoiaoee tittub alenunta are a— en*-
lin a oaaiag of one of the weli-known lofnu. nieh ae ahown in Fici.
ELEMENTS OF TELEPHONE SET. 1071
In all oommeroifll forms, the dectromagneto are made quite short and are
mounted directly upon the permanent magnet. The oorea are of soft iron
and are almost completely cohered by the ooil. In 8ingle-|>ple receivers (see
Fk. 2), but one end ot the bar magnet is used, one ooil and extension
pob sufficing. For such the permanent magnet is usuallsr compound^ wad
the coil and pole circular in section. In double-pole receivers (see Fig. 8)
both poles of the permanent magnet carry soft iron extensions, both corea
and coils being of oblong section.
The 8oft iron diaphragm of circular shape about ^ of one inch in thick-
ness and 2 to 2i inches m diameter is secured by its ed^es in a manner to
clear the soft iron extension cores from A to ^ of an mch. The magnet
thus exerts a continual pull upon the diaphragm, tending to distort it, con-
cave inwards. When the alternating telephone currents are admitted to the
receiver coil, part of each wave assists the permanent magnet by its electro-
magnetic influence, increasing the attraction and causing the diaphragm
to further approach the magnet. Haat portion of the current of opposite
sign detracts from the magnetic pull and allows the diaphragm to recede
from the magnet. The diaphragm thus takes up a vibratory motion cor-
responding to the electrical waves supplied to the coil, and it imparts
motion to the surroundinc air, which rmlts in sound waves.
Receiver casings are of various shapes, the shape beingdettfmined by
the siie of the parts and the dictates of convenience. The most usual
form is the hanci type shown in Fi|^ 2 and 8. The second common type
is the "watch-ease receiver " shown m Fig. 4 and used where a small instni-
ment is required. Lastly, there is the head telephone, in shape much
like the watoi-case receiver, but provided with a spring head band to hold
it to the ear, leaving the hands free. The shape of the air space between
the diaphragm and the aperture in the ear-piece of a telephone is of prime
importance. This air space is now universally made Bhallow, from A inch
to A inch in depth, and of an area nearly equalling that of the diaphragm.
A rdatively small hole connects the air space to the outside air.
Many kinds of receiver are now manufactured and are upon the market.
Detailed descriptions of these may be found in the trade catalofiuee, the
later works on the telephone, and in a series of articles by A. V. Abbott
n the Electrical World and Engineer, VoL XLII.
Miagnvto Vraaamlttem. — The ordinary receiver will also oper-
ate as a transmitter, and it was thus originally used by Bell. It is so mis-
irably inefficient in this r61e, however, as to have been almost immediately
rupeneded by the battery transmitter. There are. however, some house-
«lephone systems and private lines which «nploy two Bell instruments in
leries, as receiver and transmitter respeotivdy. When so used the dia-
phragm of the transmitting instrument should be much heavier and lareer
han for receivers if the best results are to be produced. At times the
peration of the receiver as a transmitter is of material advantage, as one
nay so use it by talking sufficiently loud^ when the regular trannnitter ia
ut of order and unusabla In this case it is, of course, necessary to shift
he receiver from ear to mouth and vice verta, as the case demands.
SAttcvy Vnuunnltter. — The battery transmitter depends for its
jperation upon what is known as the microphonic action of a loosely formed
leotrical contact. It is found that if a souree of steady or constant electric
otential, such as a battery, be applied to a loose eontact, within limits the
Lirrent which will flow will be in exact proportion to the pressure between
le contact points. If, therefore, one contact point be hdd stationary and
le second be clamped lighUy between it and a diaphragm vibrating under
le influence of a sound, the pressure between the contact points will vary
ith t^e motions of the diaphragm to produce current fluctuations exactly
>rre8ponding to the sound vibrations. It was at once found that under
3 circumstance must an actual rupture of the circuit be allowed to occur
i the loose contact. It was also found that carbon of all conductors could
9 subiected to the greatest extremes of pressure within the range of true
jerophonic action, and because of this property it is largely used for trans-
itter electrodes.
9tmflrl«-C«raitfftct TmBarasittor. — Of the early successful transmit-
oni, the Blake is by far the most important, obtaining at one time almost
liversal use, although it is now almost obsolete. In this^ transmitter
.e microphonic action took place at a single contact point between
slobule of platinum, driven by the diaphragm, and a button of carbon.
I
TBLEPHOMT.
nng. uia Bla^ tnuunuttfr could ba used for bol
oompKntively ahort linn, becausa o[ (hefBct UimtiU
ooDtsct 19 only nutable far ooinpmtivriy ir««t
n el the HumunCB tjrpt the i
obtAined fron
MBlU.C*B«»a« VrauKlHeia. — The multi-
ple OOntaet tr*naTnitt*r nf thn Rjm. Mr TtnuniniFm
!*M tb« tl
wid impcovtmnt* nulnuiuiMd ia (b
typOL derdopad by Anthony White.
E«U tranamir- ' "•- " —
— phiMiic butliA oc . .
Fia. S. Section oF (urroundiDC 'whieb i* a auum of cumulated cmrDou
Blaka Truumitter. approuhioE lUnDOwder in ■ppeannoa. Tlie decttM
J>, duphrapn ; iS. ciraoit I* froin one to the other electrode thmucb tba
nrbon apfinji ; 3", ftrmaalar maB. Aa long aa the granular earboD ic
platinmu spring : L. kept in a wndition of looamiw or "liyhlawu." nidi
iron brasket; /\Bd- a (mumitler with its multitude dT mioroiihaue
iuitinc acre*. oontact point*, •ome in write and aorae in pMallcl
coDjieclion. ia ideaL The renatance of audi a timns-
milter ia capable of a itbanga. many tinue that of a ainale eootact,
it bwoc prutioUly impotoible to actually break the electric cucuit. Un-
fortunate it baa proved to be abooat iznpoflaii^ to keep ^e man at cran-
ular carbon in a kwae ooDdition, there beins a tendency to a "padunc"
which rapidly reducea the effieieney. The oolid-baek tinnamittar larceJy
owea its lucceaa to ita ability to wiuietand thia aaoking tcodncy.
I»«M)r«iniaB mf H*ll«l Baek " •EimmamUtmr.—ThwmAitijl the
tianiiniitteT ia usually the only part in view, the operstins parts being witbin
It. The Inumnittar front ia supported by the|on«4hapedb»ak, and canw
all the parts. This front ia very stiff, and the mouthpiece cf bard rubber
scnwi into it. The olununum diapbraom lies in a raasptade eut (or It in
the rear of the front. Tbia diapbrsjpn haa a rubber band anapped over ita
penpliery. an anulua of rubber being thus formed upon eaah taoe at iU
This pniyidn an iniuUted auabioo a«t for the diaphrasTO. Damping
seourdy and at the same time ii^eveat its aaBtiming any but forced
In Fig. 7 b shown the various parte of the tnionphone button. Ilie
electrode chamber is formed out in a single pieee, an insulating lining td
vamiihed paper oovehni its cylindrical side watle. Tie bu;k electtode ia
Dompoaad of i ' " . f. . . .
The mica diaphragm m ia perfon
slamped by the out u, whioh e
IB down upon the
Theahamberis now charged with granules, the front electrode is pkaeed in
poaltionand Ibeedgeof the auxiliary mica diaphragm clamped Ii A tty by
the clamp ring f. whioh screws down upon the ohuober. "Hie nanuHs «
carbon are insulated from the aide walls of the chamber and-theiroot eleo-
trode ia inaulated by the mira mounting, bo that an tdeotric circuit may he
led through the butloo from eJcclroda to electrode.
The completed button in now secured between the main diapbra^^m and
pie«. Tbe Btud H' (Fig. S> has a neat ^^e bridge, while the front elee-
trofle ia secured to the center of the diaphragm by tHe elud md nuta sbowu
in Fig, e. ^VlIm everytbins is adjusted, a set nut clampa the stud W in
place. A small flexible insulated wire extends from Ibe fronl eleetioda to
u msulated tenninal upon the bridge pieces the metallic body serving a* a
termiDai for the rear electrode.
Tkevibratiena of thediapbrBganare conuaunicated to the front electmle
^
ELEMENTS OF TELEPHONE SET.
1073
7 the pin. which forms a rigid connection between them. The deetrode,
mng a certain freedom of movement within the little chamber, rariee the
assure on the layer of carbon granules between it and the back deetrode
ereby setting up the usual variation of resistance required in a carbm ^
liter. Tlie aeaign of the instrument is very
od. The two electrodes, being of carbon,
chly polished, make excellent contact with
e carbon granules, thus affording the best
portunity for wide variation of resistance
der vibration, while the carbon electrodes.
ing soldered to brass disks, have good
itallio contact obtained with Uie two sides
the primary circuit. The "packing"
Bculty is nearly obviated in this form of
nsmitter. The space in the chamber is
t partiattv filled with carbon, and the
.ce around the edges of the electrodes ^ . , -„.-,- , , ,f^
itains a certain quantity of it, which is not tfoa®? ?* back etoctrode; W.
9ctly in the circuit, and does not become electrode chamber ; P, metal
Fia. 6. Section of Solid-Back
Transmitter. Af. mouthpiece;
D, diaphragm; B, front dec-
bridge piece; d, set screw; m,
mica washer; p, threaded pin
on front electrode: «, ruboer
band; /, damper; C, case; F,
cover.
ted by the current. Any exJMUision of
granules immediately between the elect-
es through heating causes a displacement
■art of the heatea carbon Into the cooler.
en the transmitter is out of circuit and
a off, the granules tend to resettle into their original p|osition.
The chamber ^ containing the working-
parts of the instrument is extrconely
smaU. By unfastening the screws which
hold the cover, the entire transmitter can be
withdrawn, the connecting cord ioined to the
iramlated binding-post havixig 6rst been dis-
connected. On account oi^ the smaUness
and deUoacv of the parts, great care is
required in handling the transmitter when
assembling or taking apart. When properly
7. Details of SoUd-Baok
anamitter. IT, electrode
&mber; i. insulating lining; set up, it needs no adjustment ; and indeed
back «aeetrode; a, brass
eking; JS», front electrode :
brass backing; p, thread
nut U; m, mica washer; u,
', for clamping m in place ;
iiread for t and f: c, cover
V; TT» nuts for clamping
there is nothing that can be adjusted unless
some radical defect exists. Figs. 6 and 7
show the details of construction by means
of a section of the transmitter mounted,
and a section of the various parts of the
chamber, and a front view of the chamber.
The following dimensions give an idea of
it electrode to diaphragm, the siies of the parts of the carbMm button
of the solid-back transmitter.
8e[>aration of deetrodes 05 indi.
Diameter of front electrode 66 inch-
Diameter of back deetrode 69 inch.
Diameter of chamber 75 inch.
Thickness of paper lining 005 inch.
Thickness of mica diaphragm 010 inch.
rht of carbon granules used — Approx. 400 ro^pms.
iiracm of aluminum, 2^' dia., .02^ thick, varmshed
on one side.
solid -back transmitter is most efficient when the diaphragm is in a
I plane, but the efficiency is not much changed so long as the dis-
snt from the vertical is not great. As the diaphragm approaches
isontal position the transmitter not only loses its efficiency, but
ill be much confusion and distortion of the sound, and at times
nsmitter may be whoUy disabled, the cause of this being that the
r 18 but partially filled with granules, and the carbon may fall almost
dy A'vray from the upper deetrode.
1074 TELEPHONY,
CoHiaieKial " SolM.Ba«k " TnuMmtiter.— Olie Bofid-bMk
transmitter manulactured by 0om« oompanies f<Mr the o|>ea market is prae-
tically a duplicate of the above, except as to unesaential details. Oae
notable ezoeption is the inverted type of solid back devised b^ Mr. W. W.
Dean. In this transmitter, the carbon retaining chamber b forxned in
the diaphragm, and, ther^ore, there is introduced oy the vibration of the
latter an additional tendency to shake up the carbon granules. In detail
design and size of parts this transmitter adheres closely to the Bell "Solid-
back" modeL
*^ Cona Plaat«r '* Type. — Another type of Agranular transmitter eon-
siderably used but not so good as the preceding, is that employing a feH
washer as the containing cnambor for the granular carbon. Such a tran»>
mitter depends upon the elasticity of the felt to permit of the relative motkms
of the electrodes which close the chamber at the front and rear
r esDoct i vel v
*^ PacklBc and Uapackliir.*' — A packed transmitter may be recog-
nised by the dullness of the transmitted tone, the life being so liar taken
out of the tone at times as to render the words indistinguishable. To
unpack a transmitter a slight jarring will at times suffice, tnis being best
accomplished by striking the casing sharp, 'light blows witn a hard object.
The best transmitter may be packed bv j^ulling the di^shragm Ibmaid
either manually or by closing the ooouthpiece with the hps and suekinc.
To avoid such abuse of the transmitter, mouthpieces are now provided with
gratings in the front and air ducts at the base.
How to Use a GmB«lar Snttov Tnuuaiittor. — Tbe electrodes
of the transmitter should alwa^ns be in a nearly vertical plane. The lips should
be placed close to the transmitter and the voice directed into the mouth-
piece. As the weight of the parts to be moved is oonsSderable, a latse pro-
portion of the energy of the voice must be expended upon the diapEragm.
When used properly, a tone of voice, such as used in orainary converaation.
should be amply sufficient, and of this soaroely any need escape to tlie aixr-
rounding air.
Indnctlosi Coll. — When the battery transmitter was first introdw«d
it was planned to connect it directly in the line in series with tin battery
and receiver. In this connection the total allowable resistanoe obange in
the transmitter is very small in comparison with the total Hne leeistanoe.
and therefore the corresponding current changes in the receiviss are small
and of little effect. Furthermore, the longer the line, the less proportioaal
part of the total resistance is the changeable part of the transmitter resist-
ance, and thus the longer the line, the lees the possib^ timnsmitting
effect.
To obviate this difficulty Edison introduoed the induction ooil oonnecthig
the transmitter and battery in circuit with the low^resistanoe primarv and
connecting the secondary in series with the telephone and Una Wrta this
arrangement, not only is the variable transmitter resistanoe made a huge
proportion of that of its circuit and this proportion made invariable with
the length of the line, but also, by makin|; the number of turns in the
secondarv winding large in comparison with those of the primary, the
Eeneratea secondary voltage is made quite high, and thus suitable for kang
nes. There is yet another effect: vis. : the variable current of the trans'
mitter circuit becomes transformed into a true alternating current.
Coaatmctlom of Indoctiom Coll. — The induction coil is almost
invariably of the open magnetic circuit type. The core is composed oi a
bundle of annealed iron wire, upon which is wound the primary, usually of
comparatively heavy, insulated copper wire, while the seoonoary <rf fine
wire surrounds this.
]>«sl|rit of the laductlon Coll. — Thus far no general method
of computing induction coils has been devdoped, the best design for any
work being found by a "cut and try" method. Usually each manuJEacturer
has determined by a series of experiments, more or lees daborate, that a
certain induction coil will i^ve good results when coupled with his trans-
mitter and receiver. He will then use this coil until something better is
happened upon. Very few comparative tests of induction coils are upon
record, and such as are, give no clew to any relation whatever between good
transmission and the phyaicai dimensions and dectrical constants oTths
coiL
CALLING APPARATUS. 1075
Aftar fettampting in vain to use as a means of calling grestlsr macnified
Burrents of the teraphone type, produced by over-exciting the transmitter,
there remained but two altemativee. Of theee, one was to parallel the
tdephone line with a calling line, each line to carry currents of its own tvpe;
frhile the second was to use the telephone line in a double function, switcnmg
ipon the ends either calling or talking apparatus as desired.
This latter method was used, hand switches being adopted until the
brgetfulnsBS of users proved that such were most unr^iable, a ♦^^^■rg and
I oalling apparatus being frequently inadvertenUy left connected together
n a manner to defeat the whole system. The hook or automatic switch
troved a fairly satisfactory means of overcoming this difficulty, being tOHJay
B almost universal use. In the first place the switch lever is pronged to
orm a support for the reoeiver, and it should furthermore be about the
oly visible means of support for the receiver. When the wefaeht of the
Boeiver is upon the prongs, the lever is depressed so that the calling appa-
&tus alone is oonneoted to the circuits. On the other hand, when the nook
ies in response to a S|Ming. the reoeiver being removed, the switch operates
> oonneet in the taUoaff eireuits.
Scalgm of Hook ovrlioMoa. — Hook switches are of many demgns,
ich manufacturer producing his preferred idea. Bfany are of equal effi-
ency. The main points to be considered, are: first, to have the switch
)rmgs perform exactly the functions desired; second, to be sure that they
sriorm no skccidental and detrimental functions; third, to have the motion
' the sprmgs limited by positive stops; fourth, to be sure that the weight
the reoeiver is ample to actuate the switch; fifth, to have a sliding motion
the points of contact which should preferably be platinum tipiMd; and,
cth, to have the hook prongs so shaped as not to injure the reoeiver. In
planation of these points, it may be said that in usual systems, the switch
7vr on rising must connect two contact points to a third in common, as
U be seen from later circuit sketches. In the depressed position some-
nes it is merely necessary to break this connection, and sometimes in
dition necessary to make a third connection. As to positive stojM it
ty be said that when switch springs are allowed to come to a position of
it due to their own set, they are quite sure in time to have the position
normal set sufficiently disturbed to disarrancje the apparatus. A sliding
)tion of the contacts over each other is desirable, as the contacts thus
mme largely self-cleaning. As to the hook prongs, it has probably been
ted that nearly all are now provided with ring aids which cannot be
sad flsaanat toe reoeiver diaphragm.
UUhk aoparatus has been worked out upon several complete systems.
I moat obvious one, emplosdng direct current from a battery wiui push
tone and vibrating bells, while still holding its own for the very short
B of some house systems and for toy lines, has proved unauited for com-
ctal telephony. This system will therefore be ignored here, but it will
nentioneid in the sections on House or Interior systems.
or general oommeroial working the polarised bell, sensitive to alternating
enta, has proved to be the beet. To produce the alternating currents
actuating it. a magneto g«ierator, «. «., a dynamo having permanent
^eta for fields, was long ago adopted, and this fact has given the name
lie syatem, vis., the " Magneto system. Recently a oalling system, a
bination ol battery and magneto calling has been extensively adopted.
i this myntmrkf ealls for the stations are made by means of the polarised
with aitematmg current, while calls towards the central or interoonneot-
itation are made by direct battery current operating an annunciator.
sending of the calling signal is effected by merely removing the receiver
the hook. This is the calling system employed with the now prevalent
amon battery'' system.
1076
TELEPHONY.
•KltUS AMD ]»mil»«IlV^ •YSVBMA HBMMnatMWB.
circuits. The first ot theee is termed series," ana is tnat sli
where it will be seen tliat the generator and bell are wired iiL
there be an extension bell as in Fig. 0. this is connected in series also. In
the "bridging" system, on the other hand, the generator and bell are
■^t£-^»
n.
H
Fio. 8. Diagram of Oonneotions Fi«. 0. Diagram showing Proper
of So-ies Magneto Bell and CJonneotions of Extension BieU.
Telephone Set.
connected across] the line in parallel, or, in other words, they are "bridged"
across the line. In case there is but one wire used for the line» the earth
serving for a return circuit, the bridges are made from the line to eatth.
Diagrams of bridging sets are shown in Figs. 10. 27, 28, and 68.
FiQ. 10.
As the requirements for operation of the caOing apparatus are
different in the series and bridging systems, it will be necessary, from
on, to point out the differences in the apparatus designed for mem.
The working parts of a polarised bdl always include an elactromMoalt
a permanent magnet, a pivoted armature canying a bell dapi>er, and two
gongs, lliese may be disposed with reference to each other in a variety
of ways, but alwasns with the same result. It will, therefore, be neceeaaiy
to consider the most general tjoM only, a diagrammatical view of which type
of bell is shown in Fifi. 11, ana a side view in Fig. 12.
The armature is pivoted to vibrate in front of the poles of th« efoetro-
magnet, the pivot lying in a plane parallel to the pole faces, being midway
between the two poles and so placed with reference to them that the arma-
ture cannot touch both poles at the same time. Tlie permanent or polar-
ising magnet, usually a very broad U, has one of its poles seeured to the
middle of the yoke of the electromagnet, while the other extends to a point
just beyond and over the middle of, out out of contact with, the amtatura
The coils of the electromagnets are connected directly together and to tha
wiring, without movable contacts of any kind.
When there is no current flowing in the coils, the electromagnet eores
act merdy as extensions of the permanent magnet, both poles of It becoming
magnetised alike and of opposite polarity to that of the free end of the pei^
1
THE POLARIZED BELL.
1077
manent magnet. The arxnatiire also becomes magnetiaed, but by induction,
with two free and one oonaecnient pole, the free polee being euob that there
is an attraction for each by uie oppooed core of the electromagnet. These
attractioDfl are not equal, except when the armature ia exactly in ita mid,
an unBtable, position. In any other position the attraction ia greater for
the nearer end of the armature than for the other. Thus the armature
naturally comes to rest a^inat one or the other pole,aa the case may be.
When alternating current la put on the line, the first impulse may do one ol
two things: it may be of direction such as to strengthen electromagnetically
the poll of the pole upon which the armature ia resting, by adding the effect
of the current to that of the permanent mafpet, while at the same time
decreasing the effect of the other pole by a similar but subtractive effect;
or the current being in the opposite direction may weaken the pull of the
poles in proximity and strengthen that of those separated. It is this
utter kind of impulse which starts the bdl. for the armature will rapidly
tilt in response to the changed attractions, only to be tilted back immedi-
ately by the suoceeding current impulae of oppoaite sign. Thia action is
^^
m. 11. liaci^eto-GeDerator and
BeU.
Fxa. 1 2. Polariaed Bell with Long
Ck>re for Ringer of Bridging BeU.
Mated for each reversal of the eurrent, the armature and bell olapper
Jdnc a double vibration for each cycle of the current.
PorlMidginc working it will be seen that the beUs are shunted directly
■oea the talking instruments, and they must therefore be designed with
ereooe to thia effect. . It has been found that with a resistance of winding
1000 ohma, using No. 33 copper wire and cores about three indies long,
■hiiwtiwg effect is negligible even when a considerable number of beUjB
placieri across the line. It is essential, of course, that the resistance be all
Umoet all wound upon the cores of the b^, as the telephone current
ag aitamating the virtual resistance due to the inductive winding is far
fctar in effect than the ohmio resistance, and again, as the ^ciency
ha beUs demands the greatest possible number of turns where effective
perating the armature.
or seriea systems the very opposite condition obtains, for not only is
beQ alwa^ra removed from influence upon the talking circuit, but econ-
dwmanae that the resiBtance be kept low, especially where several
Be of Apparatus are in seriea. Eighty ohms is the usual resistance for
a bellfl, and the cores are made much shorter than for bridging bells.
icently a type oS bell known as "biased" bells has come into use for
.in party line systems. Such bells have in addition to the features
e mentioned, an adjustable spring which serves to give the armature a
in one direetlon so that it wiU always come to rest against the
pole piece.
TELEPHONY,
Ab pTwioiuly noted, (he nu
■teel approxiniBtely )' X 1' in
irovided with m field bj
J are uned. three bema
luUy cold bcot from bu
■mstu™ turns. The annatnlTia of xhTH.
rt>n,_ and wuund full with fitie wire. Tltf
IB size of Hire vary noniudenibly vith the
esignKi. The winnuie is driven by baul
0 tbkt one will ordinarily drive the «ma-
ture about 1000 revolutians per minute. At this speed the proper potenttAl
tor DpeTstine tbe bulls ehould be delivered. This latter ranges from fortj
vnlla up, eenes ayetem machinea usually geiierBtiot a higher voltage and
I — * .L — *L__^ j^j. ijj^tjgjng gjTReniB. One tcmunal of the i
le for which the appan
iTDnafa s aeKr train arranged si
ireabout lOOOre--'-- -
It pint
between tbe dri\
a of deeign upon which conndecsble tboncht 1^
is the interpuflition of a flexible u>riDX eoupMiw
PACrOBS AFFECTINa T&LSPHONB TRAN8M188ION. 1079
ilmyi Mods to cboka of! uwraiitinf cucrsnu pawiiig throush
WMk ill bMhiTB litduauitn,
to Mill of ' '
ile^iDDy, dujkis or>il«, retiMtl&tioa coil^inductanoA coils, Knd, »l(bouffh
•□tirely prop«ly, impftd&Dce coila. The inductance of i coiL auch u
"Oftivor nr a bell ra^gaot hAA A reducijiE effect e(iii»i to » Uio^ lemth
- -..J « J--, .».ii -.,ii-. i.^ o^..;.^ :« . ij.^- „.. yne l&Tge one. will have
Complete Macneto-Ball Fio. 16. TheBridsins B4.
« which renden the bridEing bell pnetinble. Inductmnc* hu
tITect, viw., it diftortB uid oonfuoes timnsnunton; the remAnn
t [aductAnoe chokefl the higher frAquBaey wbvea, i.«,, tbe bi^b
more thAn the lower. Even vhen pnoflDt Ln imkll dflcree, il
tct of c&incity or condeaaers ig hI« twofold. Cepecity placed or
roas a line oonductd tbe telepbone current, but afTordfl a freer
i« hishsr frequaticiea. It thus reducn the volume of tbe whole
n And difltorti by ebunting out tbe higb pitchee. In aerii«
£ho diBtcH'tiiic effect of c&pactty ia juel the opposite of UiiA. It
IB low frequmcv and permiia the puuge of a diBpraportJonBl«
hu;I> /rsQuoncy current.
exwts in Ita abaniina rdlation, in all Unee. becsuee every pair
the form cif b oondanser nf thin pUles. It is used in this rda-
Une vrhenevcr it is deurabla to permit the flow of altaroaling
to stop tho flow of dirtel cuirent. Similarly it must be under-
-eat the flow of ultematinE rurrenU. Capacity and iDductimoe
1 in oonjunctiDn, each to partially aeutraliie the effect ol the
XAXUpl* of aucli B uM ia Ibe ahunling by a ooDdeager of a relaj
1080
TELEPHONY.
the ooil of which is necessarily induded in aeries in s fAHring circait for siff-
nalini: purposes.
Resistance aets just as would be escpeoted, to attenuate the tdephens
current. As all component periodicities are reduced equally, howersr,
there is no distortion. Leaving out of consideration the condneticHi cT
direct currents, the only case in which resistance is of mudii importance
is when it is combined with distributed capacity. For a lone time Lwd
Kelvin attempted to apply his KR (capacitv resistanoe) law to tdepfaoae
lines, but this law has been found to not fit the case. Tne beat lisht upon
the subject seems to show that the combined effect of distributed capacity
and resistance is nearer proportional to the square root of their produei, th»^
« VX A. rather than the product itself.
Besiaes these three most important factors, there are sefveral other,
though less important, effects. Among these there are tosses due to Foo-
cault or eddy currents, hystwesis losses, and reflection losses. These lest
'^'eaggaaaj ■■■'■■ '■'
8]^aturns fOr^ B.W.a
Stitftiafor 12 ftl.B.S.flk
B
Loop 2 inches fron\
Insulator
Fxe. 16. Regular and Fob Transpositions.
occur when there is any abrupt and considerable change in Uie transmit*
ting medium. Thus, for instance, where a line of almost no inductance
is connected directly to a line of very high inductance, such as is used in
the Pupin system of transmission. These reflections are analogous to the
reflections of light and sound. In most telephone work little conatderatioB
is given to theee last mentioned losses.
EARTH CITRRBNTS.
MAmlH CVBBBHTS, XVDVCTIOH, <:»OM.TAI.K.
Wbsi tht UlislioH KU Ent adapted, all tinea wve imrlceii lu "crounded "
fliiU. Tbll u. but ons win wu UMd in oonuection with aa orth ra-
1L Ai lani aa the lina were fairly short, and thcia naa an laoanaidcT-
s lo distuHuDg «arth curreata only ia timea of faoaral maffnatia atomu.
(hi diiiurbaiiMa occurrBd, howHvw. at all timw.
t has bscD found that ths earth ia Bub|act Co eontinual pot«a1ial Buctua-
u, uaualty minute, but chuicing mih sreat rapidity. These eauae
itrbinc nicmU to Bow over grounded tdephone linn. When peich-
ng iiolity liaea sl» use the euth ai a return, nounded cireuita b«-
t unbearable not cnLy from the earth palential dislurbaQceg. but alas
1 inductioo. Thil laller effect ia due tfl a mutual induetive action
nen the Maphow and nei^hborins wire*. Induclioa may be due to
ing Sett of Araee about a wira carryinc a diaturbiog ci
up a cofrevpondiiic field about a parallel tclcDhone
J mduetioD it caum by a aeriea of rapid ndiatribulJoa
Fra. 17. Tranapontbns on Twenty-Wire Idnea.
aoe in the neighborhood of the diiturbing wire. That it ii thii
t to irhicb mogt tine induction may be traced woa proved by
in m Beriea of moet Lnt«r«tinE enwimenla. reported in ISSB to
ork Eanetric Club, and in ISBI to the American Institute of
Ic iH thR nKTT^e eiven U> induction or leakage from one telephone
liBtinsuiahed by the faint sound of voices.
tc da^iaita. — With a. ,_ ^_
I pr&cticable. to do away entirely with dliturbaneee. It a.
ot iDtsrfsre materially with converaalion. By metallic circuit
llii^^e. bSth*rf wh*™™ bThave t?^nl? aSd nimil'ar^^
iatADCe, tlie aame capacity, and the ume uimlation rcsialance.
4>tla luntw should be equally eipoaed to all disturbing inSu-
1082
TELEPHONY.
enoes. With insulated wires this last condition ia easily obtained by tvfirt-
ins the two wires about each other to form what is called a ''twisted pair.*
With bare wires "tnuuqioaition" must be resorted to.
Open Wire Ciro«ita. — Open wire circuits are carried ui>od pokiL
or in citiee, sometimes upon house-top fixtures, although this latter type
of construction is rapidly disappearing. The i»inciples underlying the
construction of telephone pole Imes are exactly simiUu* to those for otlier
lines. The factor allowea for wind-pressure and for weight of ioe fran
sleet storms must, however, be proportionally greater than for most otlar
k&ads of lines, because of the large exposed surface of conductor.
CroBe-arms for tel^hone lines are usually 10 or 6 pin, tiie wiree
to ^e pole being 16 inches apart and others 12 inches apart. Cr
are mounted two feet apart. Poles are usually set to gire an average ^laa
of 130 feet, Le., 40 poles to the mile.
The requirements for metallic circuits dictate that both wires of a par
shall be of the same diameter and material, and that they shall be placed
in adjacent positidns on the same cross-arm. Furthermore, at intervals the
two wires must change places, in a manner such that both shall have the
same average distance from all disturbing influences. This inter^iaage
of wires is termed "transpoeitton." In case of extreme expoeurcL sudi as
whore telephone signal-wires are run ui>on the same poles as high-teoBOB
transmission lines, continuous tranq>oaition may be resorted to. Under
ordinary conditions of tdephone praetiee, it
is found satis&Mtory, hovrever, to tranq>oae the
wires upon a sjrstem which _ treats each two
cross-arms aea jMur, i.e.t 20 circuits as a grouft
and which provides for the transposition of each
with reference to its mate ana to disturbing
untransposed wires, at least once eat^ mile.
Tliis brings " tranq>o8ition poles" one quarter
_..!_ , ...«-_, . Ad»-
Fx<3. 18. English Method
of Transposing Metallic
Circuit.
mile, or approximately 10 poles apart.
gram of inia transposition scheme is shown in
Fig. 16.
>ig. II
Fig. 17 shows a diagram of this transmissioo
system, a study of i^ich will show that only
those wires furthest apart in the group, transpose upon the same pole. For
very long lines a further refinement must be introduced treating four eroee-
arms as a transposition group, for it has been found that oross-taUc will oooor
between alternate arms of tine two-arm system. Fig. 18 shows a method
of continuous transposition.
Recently much of the transposition has been of a tsrpe known as sins^e
pin. This is much cheaper than that shown in Fig. 16. By this method a
cross over of two wires is distributed over two spans of the line, the actual
cross taking place at one pin of the middle pole. This pin is provided with
a double groove transposition insulator, while its mate carries none. In
the first span, one wire passes from its own pin position to the base of the
glass in its mate's position. It then continues m this position while the
mate wire passes over to the position in the second span vacated by the
first wire. If both wires be tied to the same side of the insulator at the
middle pole there is no danger oi a short circuit.
The properties of^ccmdu^ra need not be discussed here. Suffice it to
say that for open-wire circuits, iron, sted, aluminum, bronse, and copper
have been used. Hard drawn copper is undoubtedly standard. Iron sad
steel are less satisfactory not only because of hi^ resistance, but be-
cause of the difficulty of making good permanent jcMnts, of deteriocatioiu
and of their highly magnetic properties with attending induotancew
Conductors laid up into cables were first brought into use to relieve
congested or overcrowded pole lines. At first they were of small copper
wire insulated with rubber or similar compounds. With the introductioa
of metallic circuits came the introduction of twisted pair cables. Such
cables are of course relatively free from cross-talk so annoying with
SAMPLE SPECIFICATIONS. 1083
nMA away cables. Because of the very high epedfie induetive capacity
rubber, and the proximity of the wires of a pair, so high a mutual
KJtrostatio capacity was introduced as to greatly reduce tranamisBion.
>r aerial lines, rubber cables are yet used in some localities, especially for
leigency and tonporary work. (General practice has, however, substi-
tad the cheaper and far better paper insulated cable for all uses.
PrapeHtes of Pap«r X»a«l»t«d Cables. — Present day telephone
)]et are what are known aa dry oore cables, as the insulation is untreated
)er, thoroughly dried. Strips of paper are loosely spiraled about the cable
e, and this is then twisted together in pairs with a lay approximattng
iches. Tlie purs are then layed up in reversed layers to lorm a cylin-
ial oore which is served with paper or cotton ^am or both. The core is
D thoroughly dried by baking, and it is run directly from the kiln to the
I press which surrounds it with a moisture proof sheathing of either
e lead, or an alloy of lead with 8 per cent of tin, this alloy bemg tougher
a pure lead.
he paper used is very porous, and beuig loosely wrapped the insulation
at each wire is largely dry air. and it is this fact to which the low
trostatic capacity and the high insulation of such cable is due. The
itest moisture will greatly impair and may ruin paper cables and the
is 80 dry that suxncient moisture may be absorbed from the air to
re them. To prevent this, the ends of each length of cable are usxially
sd" with parafl^ for a few feet, and whenever a cable is cut at an
led «pot, it is immiediately "boiled out" by pouring over it hot paraffin-
obaUy the oreateot number of cables now in use are of No. 19 B. and S.
e wire, whue of those being manufactured the greatest number sire
Oi 22 gauge wire. For long-distanoe lines cables have been used of
18, 16, 13. and 10 gau«e.
blee are known, according to their use, as aerial, distributing, under-
id, and submarine. Aerial cables are made as light weight as is con-
it with durability. The usual sizes are from 15 to 100 pairs,
iributing cables have a thicker sheath than aerial, but are made in
the same sizes. Underground cables are used in conduit beneath
reets. The usual sizes are from 100 to 300 pairs if the size of wire
>. 10, and 150 to 400 pairs if the wire be No. 212. Underground cables
been made up to 600 pairs, but such cables are not practicable at
it for general use, as the allowable diameter of cable is limited, on the
ftnd, by the size of the conduit duct, usually 3 in. in diameter, and it
ted on the other by the electrostatic capacity. The smaller the cable
ven number of pairs the higher the capacity per pair,
il recently submarine cables were all rubber covered and of not over
*s. Now paper submarine cables of far better insulation, less electro-
capacity, and a greater number of pairs of wires have been success-
e\'«lopeci. These cables are of from 30 to 150 pairs size. The lead
18 UBuall^r thicker than for underground cables, and after being
with jute is covered with an armor of steel wires.
following sample cable contract written by A. V. Abbott sets forth
iar form the details of several types of cable.
CABUBS.
(A. V. Abbott.)
men: — XJnder the conditions hereinafter specified, please deliver
>'«vlnc enumerated telephone cables free on board cars at freight
reel, marked , containing jfeet of
B. and S. gauge, ps.ir, aerial (or underground) paper
kpaeity — ^— to -^— ^ m,f. per mile, inch plain lead (or
— per cent tin) at quoted price of ' " ■ ■ ■ cents per foot
'ked , containizig, etc.
.«BC<s»ra« —^ Each conductor shall fully and throughout its entire
sfcve tlie diameter corresponding to the gauge stated above, and
I
not more than
...25...
ohms per mile of
not more than
■ • . ol . • •
ohms per mile of
not more than
... OO . . .
ohms per mile of
not more than
• • • 9f . « •
ohms pw mOe of
not more than
. • . Ov . . .
ohms per mile of
not more than
. . . 95 . . .
ohms per mile of
1084 TELEPHONY.
shall be eylindrical and free from imperfections. Hie matarial of the
ductdtrs shall be soft-drawn copper.
CMavtotlOB. — Each eonductor shall be insulated with ooe for two
reverred) wrapping of dry paper; the insulation of one oonduotor m eaek
pair shall be colored blue and that of the other conductor red.
If «Bil»«r ^f Pisiiw. — Each cable shall have the number of pain
called for above, plus at least one extra or additional pair for each ene
hundred (100) or fractional part of one hundred (100) pairs o£ condiMtatB
called for.
TwiatlBff- — The two wires of each pair shall be twisted together with
a uniform lav, not to exceed f4>proximat8ly three inches for No. 19 B. and
3. ffauge ana smaller wires, ana approximately six inches for laisar wins
in a complete twist, so as to effectively prevent cross-talk.
CAbltmiT' — The twisted pairs shall be laid up into a eylindrical ooc^
arranged in reversed layers, so that the length of each complete turn dial
not exceed thirty inches.
9lto«tli. — The core shall be incased in a cylindrical sheath of jifma
lead (or an alloy of lead and per cent tin) of the thickneus specified
above. The sheath shall be free from holes or other imperfeetioDa and
shall be of uniform thickness and composition.
Cosulactor Hswlatanc^. — Each conductor shall have a reristaaea
equivalent to
No. 16 B. and 8. cause eabis:
No. 17 B. and 8. gauge eabk:
No. 18 B. and 8. gaugie cable:
No. 19 B. and 8. gauKO cable:
No. 20 B. and 8. gauge cable;
No. 22 B. and 8. gauge cabla
All measurements to be made at 60 deg: F.
The conductivity of any wire shall be equal to at least 98 per oent of
that of pure copper.
Iji»«laUoai B«nlataMC«. — Each wire shall have an insulation re-
sistance of not lees than three thousand (3000) megohms per mile at 69
deg* F., when tested at the factory in the usual manner, and shall have an
insulation resistance of not less than five hundred (500) mes^hxns per miW
at 60 deg. F., when installed, spliced, and connected to office terminals;
each wire being measured against all the rest and the sheath grounded.
Electro«t«tlc Ca|Mcltj. — The electrostatic capacitv of the wires
Aail remain inside the limits specified above (see p« 889) . Theee limits to amdy
to measurements of each wire anainst all the rest and the aheath grounoed
and at a temperature of 60 deg. F.
PacklB^r aad AlitpplBC* — The cable shall be delivered on reels in
lengths specified above. At least eighteen inches of the inside end of the
cable shall be brought out through the side of the reel so as to be aoceosible
for testinsc. This end shall be seciuvly boxed to protect it from meefaameal
injury. The outside layer of cable on each reel shall be properly wrapped.
and each reel shall be incased in stout lagging. Each red to carry in plain
sight the company's name, the above specified identification mark, length
and sise of the cable.
Delivery. — Reel marked , shall be delivered at
on or shortly before 190 — . Reel marked : — at
on or shortly before , etc.
nKeaaaremeaite mmA Teata. — The company roeerves the rii^t Co
send an inspector to the factory to be present during the process of mann*
facturing and to test the qualities of the materials used and the ^ectrioal
properties of the cable before shipping. He shall have the power to reject
any material or cable found defective. Such inn)eetion, howerer, uMdl
not relieve the manufacturer from furnishing perfect material and satis-
factory work. Final measurements and tests are to be made after the
cable IS installed, spliced, and connected to office terminals. In case the
cable falls so far tihort of the above specified requirements that the company
is not willing to accept it, the manufacturer will be called upon to examine
the work done by the company, and, if able, by remaking spCoee or repair^
ing injtuies to the cable received in handling and laying, to bring tiie cable
SPECIFICATION TABLES.
1085
to ils roquiremoDU: the cost
pany. If " ' *
up
of the work ahall be borne bw the com-
auoh work, however, does not bring the cable up to the require-
ments, and the cable is shown to be defective in material or work done by
the numufacturer, then the manufacturer shall make the cable good by
replacing as many lenj^hs as may be neoessarv^ and shall not be entitled
to pay for work done m examining and lemakmg splices. The company
wiUt u the manufacturer fails to do so, perform all the work of testing and
remaking splices, and charge the cost ox such work to the manufacturer in
ease the daeot is found to oe due to ]MK>r material or workmanship on the
part of the manufacturer. The manufacturer shall be notified as soon as
the company's inspector reports any defects, and he may have a repreeen-
tative present durinc such tests and work done by the company to detect
or repair defects. The company reserves the right to have a representar
tive present whraever the cable is tested or work is done by the manu-
facttirer in repairing defects.
C^«Ar»iitoe* — The electrostatic capacity shall not increase, nor shall
the insulation resistance decrease, beyond the qieoified limits due to defec-
tive material, manufacture of workmanship, for a period of years
after the cable has been installed.
a^rimmmU. — Payments for the cable shall be made within thirty (30)
days from the receipt of a consignment, except that fifteen (15) per cent
of the price of each consignment shall be held thirty (30) days after each
separate consignment is mstaUed and accepted by the inspector of this
eompany, who shall make a written report accepting or rejecting the cable
within twenty days after installation; m case or rejection a written notice
and statement of the defects shall be sent immediately to the manufacturer,
and if the manufacturer fails inside of ten davs to remedy such defects
they will be remedied by the company and the cost deducted from Uie
final payments, or if the percentage is not suflScient to pay for such repurs
the manufacturer must refund the difference.
(Signed)
Telephone Company.
•PSCIFICATIOlVft VOM TBUPVOMS CABUBS.
Vtotola I. >- CaR»«U7 mt A«rtal VeleplioM« Cables.
BevUed by John A. Roebling*i Sons Co.
Approxi-
Thick-
Approxi-
Approxi-
mate Cost
Nnm-
B.ftS.
Gauge.
ness of
Capacity per
mate
mate
per Foot,
f.o.b. Fac-
1>er of
Lead,
Mile,
External
Weight
per Foot
Paira.
Inch
Manufactured.
Diameter
tory,
Meas.
in Mils.
in Pounds.
in Cents
(May. 1907).
10
19
t
.06 to .066
.800
.986
14.0
10
20
.086 to .09
.700
.9
12.3
95
19
.06 to .086
1.07
1.7
26.6
9B
90
.066 to .09
.97
1.30
20.
95
22
JL
.10 to .11
.76
.96
14.6
00
19
JL
.06 to .066
1.41
2.7
42.6
00
90
JL
.066 to .09
1.28
2.16
88.8
00
22
JL
.10 to .11
.99
1.6
26.
75
19
r
.08 to .066
1.70
8.46
66.6
75
20
'
.066 to .09
1.66
3.08
48.7
75
22
JL
.10 to .11
1.19
2.2
36.0
lOO
22
A
.10 to .11
1.36
2.68
43.
1086
TELEPHONY.
Meviaed by John A, Jtoebling^t Son* Cb.
Appioxi'
Thiok-
Approxi-
Approxi-
mate CoH
Num-
B.ftS.
Oauge.
nenof
Capacity per
mate
mate
per Foot,
flcb. Tm-
tMrof
Lead,
Mile,
External
Weisht
perlroot.
Fain.
Incli
Manufactured.
Diameter
tory.
Meas.
in Mils.
in Pounds.
InCenti
(MayJSiJ).
25
19
A
.06 to .006
1.07
1.7
25.5
25
20
X
.086 to .09
1.
1,64
23.5
25
22
S
.10 to .11
.790
1.15
16.
60
19
;
.06 to .086
1.41
2.7
43.5
60
20
£
XM6 to .09
1.31
2.46
«7.
60
22
1 w
.10 to .11
1.02
1.86
27.5
100
19
'
.06 to .065
1.96
4.6
74.T
100
20
.065 to .09
1.81
4.1
64.6
100
22
f
.10 to .11
1.39
3.
46.5
160
19
,
.06 to .085
2.33
5.8
90.9
160
20
■
.085 to .00
2.16
5.2
86.3
160
22
.10 to .11
1.64
3.77
61.2
200
19
.10 to .11
2.94
6.1
116.
200
20
i
.10 to .11
2.1
5.47
89.
200
22
1
i
.11 to .12
1.84
4.45
76,1
260
22
'
.11 to .12
2.08
5.00
89.0
300
22
.11 to .12
2.21
6.7
102.
860
22
.11 to .12
2.3
6.3
115.
400
22
■
.11 to .12
2.5
6.8
122.
K
ftiaeSS OF CABCKS.
Conduita as now built readily take a 2i-inch diameter cable, and possblr
one 2|-inch; so by existing construction, cables are now limited to these
sizes, and design must accommodate itself thereto. It appears dear-
able to iiave about seven varieties of cable for subscribers' lines, and thrR
varieties of toll and trunk-line service. An appropriate set of cables it
the following:
Purpose.
Subscribers* lines, distributing cable ....
Subscribers* lines, distributing cable ....
Subscribers' lines, distributing cable . . . '.
Subscribers* lines, main and difttributing cable
SubSGribers' lines, main cable
Subscribers' lines, main cable ....'...
Subscribers* lines, main cable
Subscribers' lines, main cable
Trunk line cable
Toll line cable
Toll line cable
No.
Pairs.
10
30
60
100
200
300
400
60O
75
50
10
Sixeof
Wire.
19
19
19
19
20
20
22
24
17
14
10
Capacity
per Mile.
.086
.086
.IM
.116
.129
.1«
.on
.086
ANNUAL EXPENSES. 1087
m AHHVAXi SXPSlVAm OJF TJBI.BPHO]Va CASUBft.
The followinc has been pubUehed ae a basia for eomputation of the annual
ehareeB to be inade against cables.
"Even with the utmost care, and in n>ite of the apparent protection
" offered by conduit and sheath, underground cables graduallpr faiL In some
, eases life is vary long, but from one cause and another, owmg to extension,
necessary rearrangement of plant, etc, a thousand and one causes <^Mrate to
injure the cable insulation and deterioration is inevitable and must be pro-
vided for, in the depreciation account.
" For undergroimd main cable from 6 per cent to 7 per cent is a fair
annual charge, while for laterals from 8 per cent to 10 per cent is essential.
Aerial cable is much more esEposed to mjury than underground lines, for
it is a constant prey to all sorts of additional destructive forces — sleet and
wind storms, lightning, crosses with high-potential wires of all kinds; the
small boy with a shot-gun or rifle, and hundreds of other influences con-
stantly attack it. Moreover, aerial lines have a shorter life than under-
ground ones, as being chiefly erected in districts which are growing rapidly
tnev are soon superseded by conduit work. For these reasons an allowance
of 10 to 12 per oent for dcspreciation for aerial cables is none too great.
" The maintenanoe to which cable wire is subjected will depend very Ur^dy
upon the rate of growth in the exchange. Where this is rapid there is a
constant necessity for rearranging ana remodeling cable plant. Under
such circumstances maintenance charges will vary from 2 per cent to 5
per cent on the cost of installation. For where growth is slow, and there
IS but little change in districts, maintenance may fall as low as from 1^ per
cent to 3 per cent. With aerial cables 5 per cent for maintenance is the
least charge which should be considered. Combining the charges for both
depreciation and maintenance the annual expense for underground wire
?lant should be taken at from 5 to 10 per cent for main cables, from 10 to
5 per oent for laterals, and from 12 to 16 per cent for aerial cables."
UrIitAliif Arrestem. — Many telephone lines are exposed to light-
nine discharges and to accidental contact with wires carrying currents which
^rould be destructive to the telephone apparatus and liable to cause fire.
AU of some lines are exposed while only short portions of others are. In
ltx>th cases protection is needed although the best practice distributes it
differently in the two cases. It is generally conceded that telephone cables
run xmderground in subways wholly given up to telephone purposes are
oaie, oerss.
It has been found that three different elements are necessary for com-
plete protection. These are : first, an open space cut-out for grounding
momeotary high-potential discharges; second, a fuse of such caliber as
to amply protect the line against abnormal currents; and third, a sneak
current protector or thermal cut-out, which operates with a time factor.
And protects the telephone apparatus from small currents, which by a
Ipradual heating effect might destroy it.
For lines exposed throughout their length, complete protection demands
All three tvpes of safety devices on each wire, and at both ends of the line.
JPor lines beginning in cable and with the outer end exposed, the central
office end fuses are usually transferred to the outer end of the cable. It
is found economical to terminate cables upon frames or strips designed to
hold the yarious protective apparatus. At subscribers' premises the lines
terminate upon a protector built up on a (porcelain block, and arranged
with binding posts for incoming ana outgoing lines and for a ground wire.
Open space cut-outs almost always consist of two carbon blocks, the
one grounded and the other connected to line. These are held tightly
rgr**"** either side of a small sheet of mica. This mica is perforated to
permit of sparking between the carbons, and it is of gauge thickness such
tbstt 350 volts difterenoe of pressure will strike across between the carbons.
Fuaee are of various construction and capacity. Best practice pre-
soribee a fuse between 3 and 6 amperes rating. Some prefer a fuse mounted
upon a strip di mica which isprovided with terminal pieces of copper, and
pome pr^er tubular fuses. Tne tubular fuse has the advantage of quite
alfeotually blowing out arcs, but it has the incidental disadvantage of at
ames blowing itsdf all to pieces upon a violent disruption.
1088 TELEPHONY.
Tbs kinds of mckk cuirent pral«c(or ue now ahnoot lee
upui thu gradual haatioc ttf MHiu BubMaiun aouitiTe to b._,
way undo- Aum« mecliaDiPAl strain and opens or frouDda ti
a coil of fiii« vnre. intarposad in th« circuit.
uKoiber. In practically all wwa osruin of (be fH^ an haU'u. ^--r—
nlation by fuiible mnt^ or fusible cement, and lbs mounting spring tmad
the adh«on and thereby move the parts to i>pan or ground the fvToit*.
An old form ie that ibown in Fi^ IS and 20, wherein the KjfteninK of the
- '' Ude within the coil UDder the pressure of ipriiiK B,
oircuit. Many mod(rn bakt eoilii, iibito
Fro. 19, Combinalion Protector. A,
line-post : F, instruinent post : B,
German-silver spring; CCT carton
blocks : M. mica sheet ; 8C. snoak Fio. 20. Plan of Combination t
different m detail, operate similarly. A disadvantace of tliis type lies in
the neDHsity of reheating it for repairs. Reositly sevtral lypee of aetf-
repairine proteclon have been produced. One such has a UMr-Amped
latch wbicb. in releasng the ^ rounillng sprin^E. reaelA ilaeU while still wum.
Anotlier depends upon shearuig a heat soflsied washer, which latMr nuty
be replaced by a new one at any time.
CI.A«HVICATIOIf OF TB1.HPHOKB I.IHni.
Every telephone line may be included in one of thne elaeess. aeeordinc
to the eiteni to which it may be interconnected with other lines.
Under the bead "Private Lines" is included all linea wfaibh hain no
facility for interconnection. They may be direct, with but two autioo^
InstnjmentB kxAted in different placee. Private lines are largely used in
cities by brokers, railways, etc., and in the country upon the prsmieee of
Hoime or Hotel Systems include Uses which are apable of intetooa-
nection, but which serve a very limitfd area, unially all within the prsnoa
ing. With this latter arrangement the aystom is tsrmal " intscommuni-
The third class includes the great bulk of telephone linea. namdy thoae
Donnected to an E;<change and capable of intemoaneiTtian to not only aU
other lines of the system, but also through toU lines, to other exchuffs
the switching operations necessary for inlaroonnecting lines ara pvtonscd.
in each eichange system the llDea are traatad in groups aooonUDK to ihs
fEeographical location of th«r atationa. The territory ted b;^ ea^ g\
REQUIBEUENTS FOB OPEKATION.
THB CKIVTBAI. OFFIOB.
Evny Mcphona diUriot hu it
s wbtn lin» may be iotcrcluiaced, Dr IboM whioli eroa (he duttiet
be coaneeud together from the approaohuif to the reeediHf vire-
. The equipment uf ■ csenlnl offim is the mull of gndual expari-
ona fe&buia after uiothar h&vlDg been kdded »■ the damAmi Eor it
r a anuU number of lines • ■witchbosnl of the utinogt gimplioitv will
.,..;-. .:__.! . 1. ■'---■imberbenom™
to ]Mm th»t it requirea several opermton to UMnd to thsi ,
is dimoulty in Douneotiuc tocetber two lines siqwuinB in fmot of tvo dU-
ferent operator* and ipaeial provisioa must b* made lo handle siuih ealli.
Three coieral lyMeais have been developed, the mulUpla, tba traodw,
and the autonutio. Thaae will all be briefly omridered. Fint, bowonr,
it seems best to review the ge ' '-— -' "- -■" ■*-
siilit from that ol an uprigbt piano. We
have ruDniog along the [rant at mid-beight a nanvw keybocrd, beneath
_n Fig. 21.
In all mwiually "operated" switcbbDards the linee
of the aubeeriben terminate in sinials and in switch
sockets, and there are provided flexible connecting
soDductoTB having tenoiDels whisb rcnstor properiy
witb the CDDtaetj of the sooket bwiUImb. These
sooket switehn are caUed ''spring iaoke." or, for
■hort, "iMlu,"*nd theyconrist of a guiding thimble
behind whieh are arraaged contact springs ol sheet
metal. The Haiibk oonduotora are usually mads
in two Isogths coupled together to farm a pair of ,
oonfMCtlog cord*, and there is anociateil with each i
er*tar nuiy cooneet her t^ephone set to them at *
will, and also means for applying ringiDK eurreat
to tbe oondtiatiiw str«Dds of the cords.
Thus far the <&«ription holds for all mtmusUr
opented switohbiumis, but from this point a difler-
eotitttion must be made iietween tbe various systemfl.
For tbe present the macneto system only will be
Donaidered. For this system the switahboard Riicnal
foroKlliu tbe attention of the operator is a "drop."
IVhen a
(
1090
TELEPHONY.
operator answens by flelectins one of an idle pair of ooils, and inaeriinc it ia
the jack oorreeponding to tne fliipial, and then connecting her telephone
to that pair of cords. On ascertaining the number of the hne deeirea, die
takes the second cord of the pair, inserts it in the jack of the dedred line,
and pushes the ringing key to call the subscriber. She then diaoonneots
herself from the cords and is ready to proceed with other conneetiooa. Ia
all early switchboards, the operator was required to also restore the drop
shutter by hand and she must still so do with man^. There are, howwer,
a number of admirable combined drops and jacks m use, where the aet of
answering a call by inseitang a plug automatically restores the drop.
There is one more piece of apparatus which has not been mentioned.
This is the "clearing-out" drcm, which serves as a signal for disoonneetioa
when a conversation is finished. It is to throw this signal that one tnras
the magneto-crank before leaving the tel^hone. In operation the "dear-
ing-out" drop is exactly like the calling or "line drop," and indeed, the
line drop may serve as a clearing-out drop. As, however^ a user may not
always desire disconnection when he rings up central durmg a oonneetioa
but may desire the further attention of the operator, whenever the drop
falls, instead of disconnecting immediately, the operator must first inquire
"ThroughT" or "WaitingT" Because of this, and because the liateiung
key through which she must respond is associated with the cords, it has
been found best to associate the clearing-out signal with the cords. Jnil
Fio. 22. Arrangement of Ringing Keys.
K
\
as with bells, drops may be made with high-inductance and connected
directly across the line, or they may be made of low-inductance and become
cut out during conversation. For clearing-out drops the former method
is always used, while line drops are made both ways.
Arrwukg^wnmmt of JRIaglBC M«ya. — It was stated aboiFa that
in calling a subscriber an operator connects alternating-current to the
connecting cords. This statement must, however, for accuracy be qualiBed.
as were the current applied to both cords of the pair simultaneously, the
fact that Uie receiver is off the hook at one of the connected stations wotdd
not only cause the disagreeable sensation to the listening subscriber of
being "rung in the ear," but in addition the call would like as not fail,
the bell of the called line being shunted bv the low-resistance receiver.
Becaase of these effects, ringing kevs are made not only to connect riAging-
current to the cord toward the called line, but also to separate the strands
of thin". cord from those of its mate and tluB listening apparatus of the oper*
ator. The exact manner of accomplishing this result will be spparent
from Ihe circuit drawings.
lVI«ltlple flwitclib^ard. — As soon as the number of subscriber!
is so lafge that the lines are spread out before several opwators, if all of
these operators are to make connection to any line, then either must two
or more oiMrators assist each other on some connections, or every operator
must be given access to all lines. Both methods have been^ tried, and
each has proved Huocessful for a certain class of service. It is genersDy
agreed, however, that the multiple switchboard, that in which every, opera-
tor has accem to all lines, is the more efficient. Switchboards of this tjrpe
are made up of a number of sections or independent frameworks set side
THE BUSY TEST.
1091
by side as though one continuous frame. Each such section aooommodates
two or three operators, and the kevboard is provided with a corresponding
number of equipments. Above the keyboard there are arranged sets of
jacks and signals, one set for each operator. These are ooimeoted to the
group of lines which the corresponding operator must answer. Beside
these, there is in each section another group of iaoks called the multiple.
This group contains as many jacks as there are lines entering the switch-
boara and eiush line is connected in every section to that jack having a
position in the group corresponding to the number of the line. That every
operator may have access to every line, a full group of multiple must be
within her i]|Bech, and this fact limits the practical height and length of the
group, and incidentally the maximum number of lines that can Be accom-
modated upon a multiple switchbownd.
As may be inferred, the connecting cords previously described serve as
the means of making connection. As before the operator answers in re-
sponse to a signal using the jack in her small or ''answering jack" group
Line 1
Fig. 23.
wrhioh eorresponds to that signal. In calling the desired line she usm the
nearest multiple jack bearing the number of that line. This may or may
not be in the section before which she sits, for as the sections are placed
0ide by side, the multiple is continuous from end to end of the switchboard,
wutd it is often more convenient to reach into an adjacent section.
!!na« B«ay Teat. — With a small switchboard it is at all times evi-
dent to the operator just which lines are busy. On the other hand with
the multiple switchbcMud, each line being accessible to many operators,
some sort of signal must be provided to indicate when a line is busy, as it
is imprsMrtical to attempt to find out by direct inquiry. The weU-nigh
univeraally adopted "bu^ test" is an audible one, a chck being sounded
in the operator's tel^hone if she attempts to connect one of her cords to
Si biisnr line. The guide thimbles of the jacks are expanded to expose a
oonmderable surface upon the face of the switchboard, and all thimbles of
corresponding number throughout the switchboard are wired together. A
teat battery becomes connected to this conductor whenever a plug is in
position in any^ of the jacks, this being the condition with the line busy.
Mow if a circuit containing a telephone be connected to one of the jack
(
1092
TELEPHONT.
thimblei in a nuumer to complete the test battery oirouit a eliek will be
heard in the telephone. To amplify the movements of the opetmtorB the
tips of the onnnenting plugs usually serve as the test oonnaetion. Tim
if a line is oalled for, the operator sdeots her plug and touobes it '^w^***^
the thimble of the nearest jaok of the desired line. If the line be basr
the oliek at onoe announces this fact positiveiY. If no click is bestfd lbs
line is free and the connection is completed by inserting the plus.
It is always a matter of perplexity to telephone users as to now opentan
may discover so qjkiiokly as to whether or not a line is busy, but mm tbt
above description it will be sssn that the work of testing a line for bsuiy is
practically incidental to any attempt at making a conaeotion with it* and
well accounts for the quickness of the busy report.
A«rt«e-]HL«lttpl« 0wltclilM»ard. — The series-multiple switehboaid
was the first developed. Tlie fimdamental circuits of this system are aboira
in Fig. 23. The jack thimbles serve for the terminals of oim wire of
the hnes, while a spring in each jack serves for the other. Witb this
ssrstem a low-resistance drop is used and it must be out off during
Fig. 24. Cord Circuits of Series-Multiple Switchboard. The Induction
Coil and Receiver are each wound in Two E9ual Sections that the
Ground Connection may be made at an Inductively Neutral Point.
versation. This outting-off is accomplished by the insertion of the plqg,
as it will be noted that one side of the circuit passes throu^ a series of con-
tacts. As a plug is pushed home, the contact ^ring a ndes up, upon the
point or tip of the plug becoming clear of the point e.
The busy-test battMv with one pole grounded is shown at B. This
must be oonneoted to the thimble circuit which is alnady in use for talk-
ing-currents. The high inductance coil / is therefore inserted, to prevent
the alternating talking-current from being earthed throiufh the battery.
It is evident how a contact between the tip of a plug and the thimble or
a busy-jack completes the battery circuit.
This system has been extensively used and is not yet whodly soperseded.
yet it has never been entirely satisfactory. This type of oomrd is e^ie-
eially susceptible to dust, because of the numerous contacts. Dirt m wy
one of these will reduce greatly the volume of sound transnutted. Ins
busy test may become over-powered by extraneous currents due to aocH
dental conditions of the line, either to make the test continnous and ** fabs'
or to countermand it. With this switchboard both effeeta are equaOy
annosring, as in one case a desired connection cannot be completed.
BRANCH TERMINAL OR BRIDGING SYSTEM. 1093
la mftj' b« mntittd by a "eat-off" upon the inasF-
_ . _ __ •rl«rla( B]rM»m. — tha bridgiiu
jT brmo^ tcnninal nritahboArd overooobva th«fl« diffleultifls, but M origt-
Dklly dcglciMd (he copena -mta snkter than the betteimeot of nrviiie
mmntad. Bridmiif iwitohboudi did not, tlwrefore, eoma itito genenl
■ue until eomblned intb the oocomon b«(t«i7 and nUy — t"'""ir A l«r
word* BB to the munato biidpng board mil not b« out of puee. For
tUi (TStem. the jaok thlraUw are divided into two partiv tlu froot one
barinc the laisar bora and bong naed moUiy tat the auy test. Tha rear
— yj^ Ug, oonneaUofL The Hoond line eoniMetioD aad two
from the drauit diacram vtiereiB one of the fMka ia ktteied to eoiraapond
to the drawins of the plog and jaok. The jaoka have no out-off faatuta.
and thua the drops muat t-- - • '- ^- ^ —-■ _.._...
Furthermore, aa tlie dropn ai
d
apd_^thiia tiia drops muat be wound to Ugh
don tocother, they mittat be eubject to
mutual iadnctive effeots to oauaa croaa-taJk, unleaa macnetieally ahldded. M
Beoauaa ol thia, tha dn>p ooiia are eooBMd in tubea of umt, which bewme M
entirely cloaed by tha armature of tha drop, and hanea diapoaa of all atray ■
field. 1
The omiMion of a eut-oR feature also tenders it neoenary to look the
drop ahutten during oonneolion. Otherwise any slight oumnt impulae,
or any rioging-euTTant aant upon the line^irauld throw not only the alaar-
ioH-out drop but alvo tha Una drops- This would signal the a — ^ — '~-
___ ^ ._.,, ._ . . „ _. ,._ ._ ,._ ^^ __ auxiliary ooil
^rbieh acts npon tha drop shutter directly, to restore it and to hold H up.
— :_u:_„ ^". :.. :_.„:_: : bv the buBv-tM* '
A by Oa plus oollar juit ai
1094 TELEPHONY.
Tmasfer Byvimwmm, — Those systems in which eaoh sabaeriber*!
line has but a ein^e terminal jack, and two or more c^pvnXan aasiat each
other in oompleting connections, are called "transfer" aysiema. Prob-
ably the oldest is one in which each section of the switchboard aooom-
modates 100 subscribers' lines, and there extends a series of tranafer lines
from each operator to every other. Upon asoertaininc the number of a
desired subscriber, out of reach, an operator selects a non-busy tranaier
line extending to the position at which the line of this numbw appear
and connects the calling subscriber thereto. By means of an order dreuit
with which die may connect herself at pleasure, and which oonneeta di-
rectly with the head telephone of the operator at the deaired aeotioA, rite
cives an ord«r for the connection of the wanted line and the proper traiirfer
fine.
In another aystem the p«urs of connecting cords of one posittoo are ccn-
nected to branch lines having single cords at each of several other aectiuos,
the transfers being made by means of these. In other systems the transfer
lines have jacks at one end which multiple throughout the awitofaboanl,
while at the other end they have a single cord and plug at one position
only.
The so-called " Express" system is a kind of transfer system where three
operators assist in each connection. One responds to the signal by exteikd-
ing the calling line to a second operator who answers, ascertains the deaired
number, and orders a third operator to extend the line to hw position. She
then connects the two extended lines and is responsible for the call.
There is no transfer system where there is not some delay caused by
the neoeesary eo-oparation of two persons, and although thie delay may
be sUi^t where there are many connections to be handled, it ma^ readily
amount to the entire time of an extra operator. Furthermore, in times
of excessive traffic due to a sudden emergency, this delay may result in
the complete break-down of the system. The success of the transfer sy-
tem is in direct relation to the efficiency of its auxiliary signals. idtM^
signals indicate at a glance the complete condition of the transfer lines.
e.g., as to whether either or both ends are oonnected to subeeribMB, ■*#[■**'*
for connection, for disconnection, to indicate mistakes, etc Tlie advan-
tage of the transfer system in comparison with the multiple syvtem ia Ha
cheapness. The cost of i^paratus with this latter goes up almost as the
square of the number of subscribers and for a large switchboard is enor-
mous. A 1000-line multiple switchboard having 200 answering jacks in a
section, will require 5 sections of multiple plus an extension for eadi end
operator of i or a multiple. This amounts to 5700 multiple jacks. Add
to this 1000 answering jacks, gives a total of 6700. Contrast this with a
5000-Une board, which, by the same reasoning, has 25 sections and 133,300
jacks. Consider that these jacks must all be caUed together and some idea of
the vast cost may be obtamed. This cost must be offset by the effioicn^
of operation, and that it is so offset is beet testified to by fact that practi*
cally aU the large manual switchboards thus far installed are of toia mul-
tiple type.
OMB CKlf TSAI< OFFICS va. 0BVKltAX..
Most of the larger cities now have several oentral offices each with its
own switchboard, yet the lines of all must be interoonneoted almost as
often as those of the same office. Connections between two different officea
must be handled by some transfer method involving two operators, with
the consequent delay, and it would, therefore, seem at first night advis-
able to concentrate all lines in one switchboard. That for a anall oom-
munity this is the case can hardly be questioned, but as the territory reached
Sows the cost of the wire plant for the lines increases so fast that the
vision of territory becomes imperative.
TRUNKING. 1095
It may not be apiwrant b« to why tlie «8tabti8hme&t of additional eentral
offices effects a saving, as lines must be provided between these. How-
ever, it must be understood that there is never more than a small per-
eentaoe of the lines of a system in use at once, and it is only neoessaiy to
provide sufficient tie lines, trunk lines as they are called, to continaously
take care of this peroenta^. The usual maximum number of connec-
tions provided for m denanmg a switchboard is about 20 per cent of the
total number of lines. Wnere there is more than one central, it ia usually
assumed that the number of calls local to each switchboard will be a slightly
freater proportion of the whole number of calls than the ratio of the num-
er of its subscribers to the total number in the system.
Leaving out of consideration the question of economy there is another
ample reason for several offices in some cities. Hiis is that there is no type
of switchboard which can accommodate satisfactorily a sufficient number
of lines. Switchboards designed for an ultimate of 10.600 lines are now
in use, but this seems to be about the practical limit, although in a number
of cities the number of lines is far greater than this.
TAVIVKIIVO.
Those calls which involve two central offices are termed ** trunk calls,"
and the ratio of the total number of these to the total number of calls
expressed as per cent of the whole is called the "tninkiog percentage."
This of course varies from sero. where there is but one switchboard, to
-well up to 90 in the largest cities. When the truoking percentage is over
50 this kind of traffic becomes the more importaot, and every effort must
be made to handle it quickly and positively, and without too great ex-
pense either for lines or operators.
The most efficient method thus far devised is that known as the calling-
circuit method. By this method each central has two kinds of trunk
lines, termed respectively outgoing and incoming tnmk lines, and each
is used exclusively for calls in the direction its name indicates. Of course
the incoming lines at one central are but one end of lines outgoing from
«ome other central. The switchboard at each central is divided, one part
being termed the subscribers' switchboard and the other the incoming
trunk switchboard. The outgoing trunks terminate in jacks and multiple
throughout the subscribers' sections, forming a group usually placed be-
neath the multiple line jacks, but above the answering jacks and signals.
These outgoing lines do not appear at all on the incoming sections which
bAve the subscribers' line multiple only. At these latter sections the
incoming trunks terminate at the keyboard in single islugs and cords.
Besides the trunk lines there are wires called calling-cirouits which extend
between each two offices, from the subscribers' board at one to the incom-
ing trunk board at the other. At the subscribers' switchboard the calling-
oircuits are available to eveiy operator, and she may connect her telephone
0et to an^ one of them at wii], by merely depressing one of a group of caU-
ing-circmt keys. The other ends of the calling-circuits connect directly
'with the telephone sets of the operators who manipulate the incoming
^runk switchooard; each calling-circuit terminating at that position where
the corresponding group of incoming trunk lines terminates.
Bietlk«« of OpvnMm^ Circuit Tnnka,
When a subeoribers' operator at one central receives a call for a line of
snother central, she depresses the proper calling circuit key, and speak-
ing directly to that trunk operator racing trunks from her own office.
I^ves the number desired. The distant operator can tell at a glance which
-trfunks are not in use, because the plugs of such are at the keyboard. She
delects one and assigns it by nving its designating number. Upon hear-
ing this assignment the subecnDcrs' operator proceeds to connect the call-
ing subscriber to the nearest jack of the outgoing trunk, which bears the
designation.
1096 TELEPHONY.
In thft meantime the trunk Bwrigning operator haa with tbe plus off the
inooming trunk tested the line of the aaked-for subfleriber of her dietriet,
and either connected the trunk thereto, and rung the subaoriber. or he
being hxuy haa oonneoted a hum or other busy signal to the trunk to aig-
nifv this tact.
It must be tmderstood that the incoming trunk operator can never talk
to any of the subscribers, i.e., she cannot talk upon any of the Unea but
merely upon her calling oirouit.
Auxiliary Trank Stfaala.
A oirouit trunk system will only work satisfactorily when equipped with
certain auxiliary signals. One of these has already been mentioned. This
is the busy signal. Sometimes this is an audible signal and sometimes
a visual signal such as the flashing of a lamp. Such signals are introduoed
upon the trunk by the insertion of the trunk plug in a jack to which the
signal currents are wired.
Sometimes a phonograph is used. This repeats, "The line is bu^
please call again," or some amilar phrases. Such an arrangement in-
cludes a telephone set, the transmitter of which is agitated by the phono-
graph reproducer.
The disconnect mgnal is an almost indispensable auxiliary. It usually
takes the form of a small incandescent light in front of the trunk operator.
This glows when a trunk is to be disconnected from a line. As the trunk
operator cannot listen on a trunk, die has no means of discovering just
when a conversation is completed. The subscribera' operator can, now*
ever, listen, and she has in addition, her regular olearing-out signals. Upon
discovering or being notified that a conversation is completed, she cleers
the cords from the jacks without reference to the trunk operator. Hm
disconnect signal lamp near the plug socket at the incoming end of the
trunk glows at once, mdieating to the tnmk operator which oonneetioaa
she must take down.
Rlagr DowM or Coaiai«« TnuUca.
Such an elaborate trunking system as that just described is, of course,
economical only when the number of calls between two ofRoes is oonidder-
able. This is evident when it is imderstood that two lines, vis., the oallingo
circuits, are required solely for carrying out the system. When the traffie
is small, but one group of trunks is used. These trunks end in jacks and
signals at both ends. When a call must be passed over such a trunk, the
operator tests through the group until she finds a trunk not busy, and
then rings upon it. This throws the distant signal. When the distant
operator answers, the call is passed to her and handled by her an thougn
direct from a subscriber. Such a call, involving two pairs of oonneeting
cords, has, of course, two cIeariniq;-out drops as disconnection signaJa This
system is much slower than the oirouit sjnstem.
COHHOIf JBATinmY tYMEm.
As mentioned in the description of telephone instruments, in some
systems the individual transmitter batteries are replaced by a storage
battery, located at the central office, which serves for the entire system.
Such systems are variously called Central Energy, Central Battery, or
Common Battery Systems. There have been sugi^sted a number or dif-
ferent ways of appljring the current from the common battery to the uses
of the transmitter, but the onlv one of practical importance thus far is
that in which the current is applied to the transmitter direotly, the oircuita
being variously arranged to permit of this.
CmCUITS OF COMMON BATTERY SYSTEMS. 1097
One of the primary festures of all oommon battery eyatems is the use
of direct eurrent or battery si^alins from the subeoriber to the oentral
ofBoe. This permits of the omianon ii
of the hand generatorj aa all eig^ i zCZlT' I
nals to the oentral office whether \_ HI
for coDiMotion or disoonnection
are made by the mere ckwinc
openinf of toa line cirouit.
or
MmUmrj Clrcvlto.
•c
u
«
In the two cirouit diagrams here-
with given are shown the rudi-
ments of two oommon battery sy-
tems. In the first (Fig. 27) axe —r--
shown two lines connected together T
and supplied from a common bat- !
tery. In this system the trans- ;
mitter and reeeiyer at the substa-
tion are shown in series. This is
a practical method of connection,
but has been largely superseded by
others jnvin^ more powerful re-
sults. Ine nnging keys at the cen-
tral are omitted from the circuit to
simplify the diagram, but they are
wired exactly as earlier described.
The battery is connected to
the line through the retardation
coil. The left-hand receiver is
shown off the hook and the bat-
tery circuit is complete, flowing
out through the signal. Tnis signal
being enersised raises its target
above the shield. The right-huid
instrument has not yet responded
and its circuit is open at the hook
switch. No current flows through
the bell drcuit because of the con-
denser. The right-hand signal tar-
get is behind the shield.
Suppose the response of the
rieht-hand station to be nuide,
'mrrent will then flow stMdily to
both stations. Hiis steady current
will magnetiie the core of the re-
tardation coil. Now when any
sudden change in the resistance of
one line is made, due to the agita-
tic»i of the transmitter, there will
be a rimuHaneouB change in the
eurrent to the other. The reason
for this is twofold; first, there is
a reapportionment of currents be-
tween the lines due to the resist-
aooe change ; and secondly, the
rapid chanip of current affects the
magnetization of the coil, eaunng
eitber inductive discharges to the
line* or absorption of the eurrent Pjq, 27.
as the case may be. Additional ....
pain of lines maybe wired off the battery from additional coils, as indicated,
up to the current capacity of the battery.
JO
3
{
1098
TELEPHONY.
In tile BMond circuit (Fi^. 28) it will be seen that the TTBngvaeot of
the subecriben' initruments is considerably changed, an induotian coil beinc
used. Another diCferenoe lies in the suratitution of a sort of quadruple
wound transriformer, called a reiMating coil, for the retardation ooil. It ie
mere chance that the retardation coil and series connected itketrunscnte
should be associated, as these instruments will work equally well wfaaa
wired to a reiieating coil, provided the parts be properly proportioned.
The operation of the repeating coil is almost self-explanatory, the eurrent
changes m one pair of coils being inductively repeated by the other throu^
electromagnetic induction. The distinction oetween an induction ooU
and a repeating ooil lies in the fact that the latter has a ratio of tranaform-
ation of unity, i.e., all its coils have the same number of iurns.
FiQ. 28.
With this repeatinjK coil system as with the other, many lines may be
simultaneously supplied by the same battery, each pair of lines, howeirer.
having an individual repeating coil. The battery must be of extremely
low internal resistance, for otherwise the varying currents supplied to
one Une might cause a corresponding potential fluctuation at the batteiy
terminals; and thus cause mmute current fluctuations on all lines ood-
nected thereto. The result of this is battery cross-talk, or battery noise.
A storage battery of large current capacity nas proved best, this usually
consisting of from 11 to 25 cells according to the circuit system used, the
corresponding mean voltages ranging from 24 to 52.
Iiaasp Slgmale.
The magnetic signals shown thus far are likely to be replaoed by Incan-
descent lamps controlled by relays. These latter are similar to telegraph
relays in function, although usually of far more compact design. Hie
contacts of the relajns control circuits local to the central oflioe, whi«^ in-
clude miniature incandescent lamps, the i^lowing of which gives the wignali
Sockets of the general appearance of jacks are used as receptacles for
the lamps, which are generally of tubular form. The lamps carry terminals
which register with terminal springs in the sockets. As a cover for the
lamp socket, a bull's-eye of opalescent ^lass is mounted with the convex
side outwards. This, by internal reflection, glows throughout, and renders
the light visible from a considerable angle.
Clrctilta of Coasmom Battery 9wltclidb«a*4a.
Common battery switchboard systems are now of many types, and new
schemes are continuallv appearing. All, however, may be referred back
to one of the two fundamental schemes. The first switchboards to meet
general adoption had jacks wired on the bridging system, each ci whidi
has two sprmg and one thimble contact. Three wires run throujdiout the
board for each line, and this has led to the name "three-wire" syvtem,
this name having been given in distinction to a later "two-wire" system.
CIRCUITS OF COMMON BATTERY SYSTEMS. 1099
Eftoh syBtem has many modifications and developments to fit different
5f oonditiona and the different ideas of various inventors. It is possible, how-
ever, to consider here but one system of each kind, and these with
• regard to fundamentals only.
Tkree-'VITIre BjBtmmk*
Tb» subscriber's Une circuit is bridged to the multiple and answerins
jacks and in addition is carried to two contacts of a relay, called a "cut-off"
relay. The armature of this relay is arranced to cause the opening of two
independent circuits when the relay is energised. From the cut-off relay
contacts the branch circuit leads on one side directly to the battery,
while on the other it is carried to the coil of a sixigle eontact relay and
thence to battery. Thb latter relay is called the '%ie'' relay, and it is
evident that it will be energised whenever the telephone is removed from
its hook if the contacts at the cut-off relav be closed.
Associated with the answering jack of the line is a lamp signal whoso
circuit is controlled b^ the line relay.
The cord circuits for interconnecting lines are used as with the switch-
boards already described. There is, however, a most admirable feature
added. This is what are called the supervisory signa^ by means of which
an operator ma^ know the instant that a conversation is completed.
These supervisory circuits are controlled jointly by the third-wire <nr-
euit, in which they are wired, and by relays wirea directly in the talking-
circuit. Referring to the circuit (uagTam, the battery circuit may be
traced through the repeating coil and supervisory relay to the plug, jack,
and subscriber's instrument. It is also evident that the rapidly alternating
current will be greatly attenuated in passing through the inductive winding
of the relay unless some iliunt circuit is provided about it. This is usually
done, the relay winding beine the combination of a non-inductive and an
'inductive winding in parallel. A condenser will serve as a shimt, and
many consider this the more desirable arrangement.
The supervisory lamps are designed to operate upon 12 volts, one half
the battery potential. There must be placed in series with them a resist-
ance equal to that of the lamp, approximately, 120 ohms. This is made
up as follows : 88 ohms of resistance coil, and 30 ohms in the cut-off relay
winding, with an allowance for 7 ohms in the wiring. Under these cir-
cumstances, the lamp glows. If now the supervisory relay dose the shunt
circuit about the lamp, the combined resistance of shimt (40 ohms) and
lamp is but 80 ohms. The total resistance Is then \60 ohms, correspond-
ins to a pressure at the lamp of but ^ or i of the battery voltage, too
little to affect the lamp.
The progress of a call may now be traced. The reoeiver being removed
from the hook at the calling station, the line lamp lights, calling attention.
The operator responds with a plug and cord. T^ corresponding super-
visory light fails, for as soon as its circuit is closed the shunt becomes
operative, as the receiver is off the hook and current flows through the
supervisory relay.
At the instant of inserting the plug, the cut-off rehiy is onergised and
breaks the circuit of the line relay, cutting it off the line. The line lamp
of course goes out. Incidentally the busy test battery is put upon the
jack thimbles, as these are at a potential corresponding to the drop of
potential in the cut-off relay, vis., 4 volts.
The operator, using her listening key, ascertains the desired number and
connects to that line and rings. As long as the station fails to answer, the
eorresponding supervisory lamp remains aglow, as the shunt circuit is
open. When the receiver is removed from the hook, the shunt closes,
ft must be noted that the cut-off relay of the called line operates upon
tha insertion of the calling nlug in its jack, and thus there is no possibility
>f affeoting the line lamp of this line.
Trunkinc is accomplished by exactly the same methods as with magneto
rvst«ins. This eh-ouits used are so various that it is useless to attempt to
rhoose one as standard. One of the most interesting features largely
i/fopted -with circuit S3rstem trunks is that of through supervision. By
bis is meant that the subscriber's operator, at whose position the call is
TELEPHONT.
■*5^5f"
^
CIRCUITS OF COMMON BATTERY SYSTEMS. 1101
first received, has in lier lamps a direct indioatlon of the position of the
hook switch of a eubeoriber of another central office connected throuch a
inink line.
Two-l¥tr« Byatoaia.
There are eo many different schemes for two-wire systems and this
system is of such recent introduction that it is difficult to select any one
which might be considered standard. One of the earlier types is shown,
LlA*
Clrautt
— ► ^J H
Cut On OCU
UnaLam^
csnotpOD
«ortf Clrotilt
Suparvltory
Lamp
QD=p?
5 £J
COa
aIj25
P
Fro. 30 Circuit of Two-wire System. Relays A, A, serve as
Retardation Coils.
RaUrdktIon -
Fie. 81. Recent Common Battery Subscriber Set Circuit.
lio'vrev'er, in Fig. 30. The out on relay severs the connection between the
line relay circuit and the line, and at the same time connects this latter to
th» jack circuits. Tlie supervisory circuit is self-evident. It mii^ht seem
-thstt the contact with the jack thimble, in testing for busy, mi^ht mterfere
-vHth a conversation by shunting off part of the current. This is avoided
tyy reducing the bunted current to the smallest amount and making this
«neetive in a very sensitive relay. This relay in turn closes a circuit which
«If eks the receiver. This test apparatus and the ringing and listening keys
«re not shown in the diagram.
{
1102 TELEPHONY.
G«HiMOB Jtattoiy Iiifltmai«i« CIrcvlte.
The oirouits of instruments are also of many sorts. One kind laifsly
used is shown in connection with Fig. 28. In this the induction ooil primaiy
and secondary have a ratio of turns of 1 to 2, and of resistance of 2 to 1 .
The transmitter affects the repeating coil directly, and in addition throush
the induction ooil causes a more intense current to be sent out on the ttne.
Another type of circuit is shown in Fig. 31. Here the ooil shunted
about the receiver serves as a low-resistanoe path for the transmitter ouxieai,
while the voice currents find a path through the receiver.
Demand for party lines has existed since the early days of telepkaoy.
Nothing really successful was accomplished in this direotion until the
advent of the Carty brid/Eing-bell. With series bells good party-fine
service with a two-wire line is out of the question, as all voice ourrenta must
necessariljr travose the bell-magnets of all idle stations. The bridsing^
bell, previously described, connected across the line^ireuit and of solii^
impedance as not to appreciably shunt the voice-currents, can be used
for a number of parties up to twenty or more so far as electrical oonBaderar>
tions go. Practically the number of stations is limited, for with the unxnodi-
fied bridgin^bell a code of signals must be resorted to, to distinxuidi
between stations. As all bells respond to all signals, confusion and annoys
anoe to subeeribers limits the numoer of parties.
With the magneto system the signal, one ring, is reserved for *«n1mg
oentral. The stations must then have signals from two up; and when
their number is large, a differentiation is made between long and sltort
rin^. With the common-battery system all signals may be aasigned to
stations.
AalecttTe Sjateaui.
Before the bridging-bell was introduced, attempts were made to aolTe
the party-line problem by some sort of selective device, which, by respond-
ing to a code of signals, would succeed in ringing the desired party to the
exclusion of others. At first all systems were what are now known under
the generic name — "step-by-step systems." Each station has a pcHot
switch, the arm of which is driven by a motor. The motor is oontroUed
from central, and drives its mechanism in a series of steps.
All motors run synchronously and they are arranged to oonneet the
bells one after the other in operative relation to the line.
Another and later type^ of selective syst-em has been developed, in wliieh
the bells work entirelKr independently of each other and of any motor
device, the selection of any particular bell being dependent upon toe eom-
bination of currents wnt out upon the line.
0tep*l»j«0tep Bjmimmam,
Probably hundreds of step-by-step mechanisms have been invented.
but it can scarcely be said that any are in general use. Both spring and
electrical motive power have been tried, but the fact that this system places
all the more complicated apparatus at the subscriber's station, where it
is most troublesome to wAl concerned to get at it for repairs and SKljust-
ment, weighs too heavily against all step-by-step systems.
Two-Party Aelecilre AyataHU.
The simplest selective ssrstem is the two-partsr system, largely used by
the Bell companies. In this system one bell is wired to ground from eaeh
side of the line, bridging-bells being used. In ringing a party the rin^ng
current is connected to ground on the one hand and the proper side ot the
line on the other.
PARTY lilNBS.
1103
M9mt>^mrty Bytm
I'
Four-pArty syBtems aeem to be the most popular, and there have now
been many eohemee for acoompUshinK selection. The so-called Newburgh
system uses what are termed " biased bells. These are polarised brid^ng-
ttells with the armatures biased to always come to rest in the same position.
The biasing means is usually an adjustable spring acting upon one end of
the armature. Two such bells are wired to ground from each side of the
line. The currents used are impulse currents of one sign only, being
comprised of a series of half waves of alternating current separated by an
equal period of no current. Two of the bells, one on each side of the line,
are connected to respond to positive impulses only and to fail on negative
impulses, these latter merely assistmg the spring to hold the armature
stationary.
After an armature has been moved by a current imi)ulse of the proper
nsn, the spring returns the armature auring the period of no current.
The other two oells are similarly arranged, but are connected to respond
to negative currents.
For the common-battery system the Newburgh system becomes mod-
ified as it will not do to have permanent grounds upon the line, and the
insertion of a condenser will not help matters as it converts the impulse
currents to alternating currents to which all bells are responsive. The
Fia. 32. Four-Party Newburgh System Arranged for Common Battery,
Two Stations wired from Line A, and Two from B,
flowigement usually adopted is indicated in Fig. 82. The relays at all
stations are in series with condensers and all operate irrespective of the
kind of current impulses. These relays connect the bells to line and that
responsive to the impressed current rings.
There are other four-party systems in which the bells respond to changes
of frequency of the current, the bells being wired with such combinations
of inductance and capacity as to make the response and failure positive.
Other systems use combinations of direct with alternating currents, while
at least one, the "B.W.C.," which at one time bid fair to be very p<4>ular
but which has now largely gone out of use, depends entirely upon various
combinations of direct oiurents.
Metliod of Obtelntmg- Impula« C«rr«»te.
The impulse currents for the Newburgh system are obtained from the
ringing generator by the use of an auxiliary two-part commutator cme
eeppcnait of which is connected to one of the usual alternating-current ter-
minAlfl and the other of which is either left blank or connected to the
other alternating-current terminal, if this latter be grounded. Two brushes
diametrically opposite each other bear upon the commutator, and these
wuce adjusted witn reference to the field so that the passage from one seg-
(
1104
T£L£PHONT.
N
OE
L«=»aq=*
Fxa. 33. Arrangement of Oenerfttor for Obtainins Impulae Carraats.
meat of the commutator to the other oceurs juBt at the lero or point of
reversal of the alternating wave.
Between either commutator brush and a collecting ring an impaba
current can be obtained.
CSITTltAIi OFnCB APPARATITS AMTXMMJLJkmir.
Besides the switchboard there is in every central office eonsiderabia
auxiliarv apparatus. The sise of the oflSce generally deteimines the kiad
re9uired. Of such apparatus, in every office of any siie, the main distrib-
uting frame is of prime importance. As it is imperative that all stations
be given as near continuous service as possible, and as it is alwajra dis-
tasteful to subscribers to have a change of number, it is found neoeasaiy
to have some flexible link in the wiring between the line cables and tlie
switchboard. The main distributing frame provides the facility for this
connection. A steel framework carries strips of terminals, to some d
which the switchboard cables are connected and to others the line or out-
going cables are connected, each pair of wires being asaignad and o<mneeted
to one pair of terminals according to some carefully planned scheme. A
flexible or temporary connection, usually termed a **croflB connection " is
run from any one pair of terminals to any other, as the service may requira.
Mun distributing frames are usually arranged with two aocesable ades.
The terminals upon one side are vertical and are supported from a set of
uprights so as to form a series of vertical runwaira netween the terminal
strips. On the othec side the terminals and framework are usually ar-
ranged in horisontal i^lanes that horisontal runways may be formed. With
such construction, wire may be run with the greatest ease between any
two terminals.
Of late years it has been considered good practice to use the main frame
as a support for the central office thermal out-outs and carbon plate arresters,
the vertical side of the frame having arrester mountings substituted for
the simple terminals. The strips of arresters are often called arrest«r bars.
The mtermediate distributing frame has only come Into univeragal use
lately. It is similar in construction to the main frame, but its purpose Is to
provide a flexible link between the multiple and answering jacks. It is
clearly impracticable to have the multiple jacks ammged in any order save
that indicated by the line numbers. The wiring of these jacks is tkersfors
made permanent once for all. On the other hand it frequently becomes
necessary to chanse the position from which any line is answered, in order
to properly distribute the work between the dififerent operators. Tw
example, Nos. 1 to 60 may call frequently enough to require two operators
to properly care for them; while Nos. 50 to 150 may require but one operator.
It would clearly be impossible to distribute answering iadcs and signals to
meet such conditions while designing a switt^boara. The question of
distribution must be met by the intermediate frame. The multiple jack
wiring connects to one side, and that for the answering jacks and sii^iUB
to the other, and the cross connection serves to connect any anawering jadk
1
AUTOMATIC EXCHANGE SYSTEMS. 1105
to any multiple jadE. It is of no momait thai aniweriog jacks be placed
in an order having no relation to the line number, for they are never sought
for by number, but only in response to an associated signal.
Of the other apparatus the most important is the power plant. In mag-
' neto offices this oomprises a small four-volt rtorage battery, sufficient to
ener^se the operators' transmitters and to opente misoeUaneous signal
lamps and magnetic signals. A power-driven generator for chaiging the
battery and power-driven ringing machines are also required.
For oommon battery offices the battery is usually of from 16 to £2 volts
and of huge capacity. The charging generators must be coneqKmdingly
large, having sometunes as great as 20 kw. output, which at low voltaJKC
means a big and heavpr machine.
It might seem at mst thought that the battery coukl be omitted as
generators must be provided to charge them, the gmerators being used
directly. Unfortimately^ the difficulty of making a generator which will
produce a current sufficiently smooth to permit of any service whatever
without a battery is so great that the use of the battery is a necessity.
The battery smooths out the irregularities caused by the commutation of
the generator, which irregularities, of no moment at all in any other service^
are entirely disastrous to telephony because of the noise introduced.
•
Thtfe are in operation quite a number of automatic exdiaoge
systems. These range in sise from accommodations for a few lines, to a
capacity approaching 10,000 Knee. The subscriber's instrument for all
automatic systems is provided with a numbered dial and a movable indi-
cator. This latter is set in some manner to Indicate the number of the line
desired. When released it returns automatically to sero and in so doing,
throxigh the agency of auxiliary contacts, it causes a selecting apparatus
at the central office to make connection between its line and the desired
line.
Almost all automatics dei^d upon the multiple i>rinciple. Each line is
assigned a switching mechanism before the moving switch arms, of which are
arra3fed contact pomts for all otho* lines in the district. There is thus one
multiple for each line. The multiple line contacts are arranged in conseo-
iitive order. For small systems they are often placed as radii of a circle
>ver which the contact arms move. In such systems the motor for the
nvitch arm requires but one motion, that of revolution. In other small
lyetems the contacts of the multiple are arranged in a single row. The
vritoh motion then become* a simple longitudinal one. As the cuMcity A
rows, the multiple contact points assume the form of a superimposedT series m
f rows, the contact of each line occupying a position which can be K>cated ■
y its co-ordinates. The tens of the number usually correspond to the ^
ertical and the units to the horiiontal co-ordinate. For such systems the
loving switch arms require two motions. If thepoints be arranged upon a
Kane surface, these motions are an elevation and a transverse motion. If
le contacts b« arranged upon the inside of a cylinder the motions are
eviation and rotation. . . , « , ..
Suppoee with such a system Number 70 b desired. Seven elevating
ipulaes will be sent so that the switch arm will traverse the vertical co-
dinate. Then nine transverse or rotating impulses will cause the arm
traverse the horisontal or units ordinate and rest upon the point 7-9.
A eeoond system, more akin to a manual switchboard, has been mvented.
this system the lines have each but one set of terminals, but there is
ovided a system of circuits corresponding exactly to the cord circuits of
unial switchboards. The starting of a call causes one of these circuits
first beoome connected to the calling line and then to the called line
lich is automatically rung up.
Whesn automatic systems are used for a great number of lines the method
ooxnpleting calls, while becoming little more complicated for the user,
x>mes excessively more so at the switchboard. It is not possible to
^^pt to explain here the scheme of operation, nor is it possible to con-
Ihe detaus of any of the smaller systems.
(
1106
TELEPHONY.
AXMIIIiTAVfiOlJA HAS OF UOrBA.
Efforts have been made to use telephone lines for two distinGt a,,...,^.,.-,
simultaneously, in two ways. The first has been but paxtially suooeMni
and contemplates sending iliore than one telephone mwwwge at a tina
The second, very succeesinil, and in everyday use permits of the wmiitor
neous transmission of telegraph and telephone messages.
Duplex and multiplex telephony depends upon the arrangenkeDt oi iht
various instruments with regard to the conductors so thai each tekpfacAs
Fia. 34. Duplex Telephony.
connects equlpotential points of the system with respect to all other instra-
ments save its mate. Thus in Fig. 34, if the resistance and capaciiy vaan
the upper branch of the parallel line equal exactly that of the lowvr Ine.
both m value and distribution, the terminals of both T* and T^ will eoonect
equipoteatial points with respect to instruments Ti and T^ Siiiularly wii
Fio. 35. Multiplex Telephony.
7i and ?*« connect equlpotential points with respect to Ta and 7*4. 8o also
in the multiplex circuit it will be found that equlpotential points are
Retardation' coils serve better than resistances, in such systems, as thec«
mav be connected to form an Inductive path for currents, the passage of
which should be resisted to prevent loss ox volume and to form a noiiriiidae-
tive path for those currents which should be conducted.
The difficulty with such systems has lain in the inability to make the two
sides of the various lines exactly alike, with the result that the supposed
Fia. 36.
LIMITS OF TELEPHONIC TRANSMISSION. 1107
aquipotential points were not suoh. Under this condition tbe two drcuita
overlap Aod croBs-talk.
The method employed for rendering telegraph eignals of no effect upon
telephone lines has involved the rounding ox the telegraph current impuJaes
to such an extent that there is no change abrupt enough to affect the tele-
phone. The first ssrstem was invented by Van Rysselber^e and after
modification is used to-day. Such a system is indicated in Tig. 36» taken
from Maver's American Telegraphy. It will be seen that one pair of wires
provides simultaneously for one telephone and two telegraph messages.
Another system in use sometimee called *' Simplex, " provides for but one
message of each kind for each two wires. Simultaneous telegraphy and
telephony is used extensively on \otut distance lines, and the application of
this system is called " compositing, while the coils, condensers, etc., are
called a "composite set."
MiiMrrs or tbugjpkoitio viijLjrsMSisioir.
The limiting distance through which coounercial telephony is practi-
cable is as yet an unknown <|uantity. Every few years the idea becomes
general that the working limit has been reached, ^hen some new invention
or construction permits of a further ext ension. The limit for the magneto
transmitter was extended by the Blake transmitter, and then by the solid
back type. The bipolar receiver has replaced the single pole. Dry and
LeClancne batteries were superseded by the more powerful and steadier
Fuller cell and this in turn by the storage battery of practically constant
strength. In the direction of the line the srouiided circuit ^ve way to
the metallic and the iron and steel wire to nard copper. This latter has
been used in constantly increasing sixes until the oommercial limit seemed
to be reached at number six B. &S.
The most obvious way of inoreasing volume is improvement in the sen-
sitiveness of the transmitter and receiver. Imi^rovements in this direction
have been at a standstill for some years. Nothmg has been found to better
the sofid back, except increase of current* and the effect of tlus is tem-
porary only, resulting disastrously verv soon. Improvements in the
receiver, on the other hand, prove a disaovantage at once, as with a sensi-
tive receiver the effect of Ime disturbances grows at a rate entirely incom-
mensurate with the increase in volume of transmission.
Anotho" method of extending the limit for speech transmlsfflon attempted
alnoost since the beginning of telephony is the use of a repeatec, in a manner
exactly similar to that which has worked so successfully in telegraphy.
Up to this time, however, no success has been met with along this line.
No repeater has as yet been developed which does not do at least as much
harm as good.
Within the lut few years an entirely new means of improving the effi-
ciency of transmieeion has appeared. This, briefly, conosts in, the change
of the electrical characteristics of the line by means of auxiluiry mduo-
tances or capacities or auxiliary conductors in a ^manner such that the
telephone eurrents are transmitted with better efficiency. «, . ^ .
The first method to be developed was that invented by Dr. M. I. Pupm
and termed "loading." Dr. Pupin showed how coils of certain known
induotance can be spaced along a line and thereby improve its efficiency.
The adaptation of such a system of course requires much study and experi-
ment. Coils must be designed which are non-interfcnng and the energy
abflorbins properties of which are sufficiently reduced so that there is a
net gain in transmission. lines are now in use equipped with this system,
but it ean scarcely be safd to have passed the expcnmwital stage. The
improvement hi transmission thus far is, as far as can be learned, ab9ut
as 2* to 1, when all conditions are normal. When, however, the insulation
of a line is reduced irrc^larly as by moisture, the effect upon a loaded cir-
cuit IS at times very disastrous. , ^ . , , ,
Two later systems have been invented. One of these involves putting
Dondensers in series with the line and inductances across the line, at regular
Intervals. This system has as vet been placed upon no practical basis.
The aecond of these systems has been developed in theory to the most
snoourasing state. It may be termed the method of "distributed shunts.
1108 TELEPHONT.
The theoretical condition to be fulfilled is that of eqoiJ Teloelty of ti .
mission for waves of all frequency; thus the condition for no distortioB «!
the wave forms. The inventor has found that to fulfil this oondition fe
must increase the inductance of the co])per line byr platinc it with -^afprl^
mat«ial such as nickel or an alloy of iron and nickel and that It mvsl be
shunted at stated intervals. The shunts consist of graphito or other bob-
inductive resistances of many thousand ohms resistance aaoh; opaced at
equal intervals of from one to several miles.
MOTBA OH COST OV VKI^BPHOITS
That the cost of telephone switchboards for laroe central oflioea inc.
faster than the number of lines is of course evident f^noi what has
said concerning switchboards. It must be pointed out, however, that
when the plant is considered as a whole, the cost for burge plants ia
Sar station than for small. The following by H. S. Kerr w the Ai
lectrieian may throw some light on this subject.
" The cost of a telephone puint can be estunated approximately on the
basis of the number of instruments installed. An exchange of 600 tel»>
phones Installed within a radius of 1^ miles without any conduit or caUs
work, but with up^to-date pole>line construction, will cost about S66 per
instrument: this will oome so near to the actual cost that a company may
base its calculations on it with a degree of certainty. As the nmnocr of
telephones increases, that radius or distance from the exchange vrill also
increase, and, therefore, the cost per instrument. In estimating on a
plant oX 1000 telephones some aerial cable and more substantial oonstrac*
tion must be taken into consideration as well as more costly equii>ment; eon-
sequent ly, there will be a material increase in the cost per instmment;
without conduit work a safe approximate figure woukl be $85 per inatra-
ment within an ordinary radius.
**When an exchange has more than 1000 subscribers, and quick, strictly
modem service is required, necessarily it must be equipped with eentral
energy and multiple switchboards, and in towns where electric Kgfat and
railways are usecf many additional appliances are re9uired to neutralise
the interference from the heavy circuits. Where it is necessary to ooa-
struct conduits it is not safe to alk>w less than 1100 per instrument for
the installation. In large cities where 6000 to 10.000 subeeribera are
connected up, the cost woiild approximate from $150to $200 per instnunent."
Besides the interest on the investment, maintenance and d^reeiatfen
are of vital im|x>rtanoe. Something has already been said with roBard
to the maintenance and depreciation of cable, but further opinion may be
of value. In 1809 the Michigan Board of State T^ Cbmmiasion armred
at the following schedule of depreciation for various telephone equipment
** Poles and cross-arms, accepting about twelve years as the average Ufe
of a pole, a depreciation was allowed of eight per cent per annum; under-
ground conduits, two per cent; underground and aerial cables, lead>«overed
and rubber, ten per cent; subscriber's station equipment, ten per eent;
switohboaras. ten per cent. For copper wire in use one year or lees, iu
full value will be taken: for two years and lees than three ymrB, two and
one-half per cent; for three years and less than five years, fiva per «eot:
for five years and less than ten years, ten per cent; for ten prears and over,
twenty per cent. This makes an annual average of about eight per oentr."
PRKVATB IiXirSS, IMVBlftCOMHnnVSCATSirCI, Jkwm
HtOlJSS SYSTBMft.
(Condensed from articles by W. 8. Henry in Atner. Blsc^ 1900).
Thus far only the central ofiiee ssrstem has been considered. For
Private lines, intercommunicating, and House Systems, verv different
apparatus and circuits are used. Such systems have been well described
in the technical press and it therefore seems sufficient to review briefly
'*-- of articles treating of such systems. , ,. . .
^« telephone systems may be divided into seriM party tmss, ortd|0»i^
^
PRIVATE LINES.
1109
u
%r partif Une$f inUroommMmeaiinp aiftlema, and rnnaU ctniral
•y«<MU« Ab the last lystam di£Feni praotically onlv in aiie from the regular
oentral station aystem no description of it will be undertaken here. In
these systons either magneto or microphone transmitters may be used, and
the signaHng apparatus may be either magneto bells and generators or the
sommon vibrating bell and battery.
Where microphone transmitters or yibrating bells are employed, the
batteries mav be distributed among the various stations or, in some cases, aU
eonomtrated at one place. It is generally desirable althouigh not really
neoessary, so to arrange the circuits that the bell at the calling station, or
the home bell as it is called, should ring whan calling up another station.
This assures the person signaling that his own circuit and probably the
I
W
K*
-^.
Fio. 37. Series System with Magneto Transmitters and Signaling Batteries.
whole system is in working order, and that his call is being transmitted to
the desured station.
One of the simplest telephone systems comprises magneto instrummts
connected in series in one line. Fig. 37 shows an arrangement of this kind
requiring at each station two magneto instruments; T is the transmitter
and R is the receiTer. An ordinary vibrating battery bell, V, a battwy. B,
of two or more oells, and a hook switch. H, complete the equipment. When
tbe receiver, £, is hanging on the hook, the line is connected to the lower
contact; when the recover is removed, a spring pulls the lever up against
IFl
Fio. 88. Series System with Magneto Transmitters and Generators.
the contact, h. The smaller auxiliary switch, I, is arranged to normally
rest on the contact, c. It may be pressed down upon d, but when released
t should be returned to c by a stiff spring.
In Fig. 38 a very similar arrangement is shown, the only difference being
a tne nrst system, ine signaling key, A, has only the upper contact, to
tornuJIsr short-circuit the generator, O, as indicated in the sketch. Some
.utonoatic arrangement may of course be used.
The above described systems are known as aeriet party linear meaning
b*t »II of the stations connected up are in series with each other. When
hiB arraxiAement is used, even for a small number of stations, the bell mag-
ets^ should have as low resistance and as few turns of wire on them as
oaaible, in order to reduce the impedance of the circuit; and the generators
bould be woxmd with rather nne wire, because the current generated
tuet jmam through all of the bells in series.
In order to avoid forcing the talking current through the magnets of the
"~* '*•*•" bells, the latter may be "bndged" directly across the circuit, as
1110
TELEPHONY.
shown in Fig. 39, in which case the bells may be wound for high
and knpedanoe so that the talking currents will pass them.
V
Fio. 30. Bridging System with Magneto Transmitters and Geaooaiora
xu^'l^?*.* ^®' **^®®^ diflferent methods of bridging are shown. At Station 1
tbe bell is removed entirely from the circuit when the receiver hook is uk
at Station 2 the bell remains constantly across the circuit in aeriea with \£e
transmitter and receiver, but when the hook is up it is short-circuited br
the hook and its upper contact through the wire, a; at Station 3 the bSo
remains permanently connected across the circuit, and when the recciw
hook IS up the transmitter and receiver are connected in parallel with h
<^^
Fxo. 40. Series Systems with Microphones and Betteritt.
Fi^. 40 shows the simplest method of using microphone trmiwmittera.
The mstruments are a transmitter, T; an ordinary receiver^; a vibratii«
bell, F, and one or two separate batteries at each station. The battery. B,
IS used only for rin^ng the bella; the battery M.B., only for operating the
microphone transmitters, and the battery D, for both purposes. In this
FiQ. 41. Series System with Microphones and Magnetos.
arrangement, as well as in the one shown by Fi^. 41, the microphonea,
receivers, and microphone batteries are directly in series with the line,
no induction coils being used.
Instead of vibrating oells and batteries for ringing, we may use a poiar>
ised bell, C, and a generator, O, as shown in Fig. 41.
A better arrangement is to use high-impedance bells bridged across the
two-line wires, as shown in Fig. 42. The generator, as is the case in I^.
39, is normally on open circuit.
^
PRIVATE LINES.
1111
Three bridging methocU are ehown. At Station 1 some of the current
from the batterv, if .B., can flow through the bell when the receiver is off
the hook, but tnie will do no harm; in fttct, it may be beneficial, for it
aHowB a larger direct steady current to flow through the microphone. The
fluctuationB in the current produced by the microphone cannot paae
through the bell-nu^net coib, but will pass through the line circuit on
account of the lower imoedanoe of the latter. At Station 3 the bell is cut
out when the hook switch is raised, and at Station 2 both the generator and
bell circuits are cut off by raising the hook. An extra contact, <f, is re>
quired at these two atations, but on the other hand there are two bells
Fxa. 42. Bridging System with Microphones and Magnetos.
less across the circuit to form shimts or leaks for the current when two
parties are conversing. On the whole, the arrangement at Station 3 is the
best of the three.
Fig. 43 represents a series party system (corresponding with that which
was shown at Station 1 in Fig. 40) in which a battery, B, and vibrating bell,
Vt are uaed for signaling, and an induction coil, /, is added to the speaking
apparatus. The primary of the induction coil is in series with the micro-
phone transmitter, 7, and its battery, M.B., and the secondary b in series
with the telephone receiver and the line.
The connections at Stations 1 and 2 are identical; when the receiver
hook, Ut is down the t>alking instruments are entirely cut out, and when it
"lo. 43. Series Party System, with Induction Coils and Signaling Batteries.
. up the signaling key, battery, and bell are thrown out of circuit and the
isun circuit passes through only the telephone receiver and the secondary
r the induetion coil. At Station 3 the oonneetions are different; when the
loeiver hook is down the telephone receiver and secondary of the induc-
911 ooil are merely short-circuited, while the transmitter, its battery, and
Ml prinouary of the induction coil are open-circuited. When the hook is up,
i« talking instruments are connected up for service and the signaling part
the apparatus is short-circuited. Fig. 42 corresponds with Fig. 43, except
sat ma^i^eto-generatoni, O, and magneto-bells, C, have been substituted in
e place of the signaling battery and vibratin(^ bells shown in Fig. 43. The
ation connections correspond also, the receiver hook, H. at Stations 1
d 2 being: arranged to throw in and out of circuit the talking apparatus
d the signaling apparatus, while the hook at Station 3 merely short-
cuits the signaling apparatus or the receiver circuit, according to its
(
1112
TELEPHONY.
position. This arruigem«iit ib the preferable one of the tub, Ibr the
that faulty switch oontacts at the reeeiver hook will not open the <__
so that there will always be a continuous line through whii^ one
signal.
A simple system installed where there was considerable noise, dirt, hI
▼ibration, is represented diacrammatically by Fig. 46. Here, there are tkm
line wires, a, o, and «, the line e forming a oonunon return for both thi
Fig. 44. Series Party System Using Induction Coils and Signaling
signaling and the talking circuits, a and 6, on which the apparatus is si^
ranged m series. In this system the talking line is never open-circuited, the
telephone hook, H, serving to merely short-circuit the receiver and tte
secondary of the induction coil when down, and to remove the short -dreoft
and close the local circuit of the transmitter and induction ooil primaiy
when up. It is obvious that the middle line wire, e, gives a free path to im
talking current, instead of its being forced through the supaling biells. Sock
an arrangement facilitates the separation of the signaling and talking ap-
Daratiis, so that the call bells can be located where they can be easily faesra
while the transmitter and receiver may be put in a sound-proof ck>set. Tb0
HM
h-^»-
Fio. 45. Three-Wire Series Party System.
disagreeable noises due to induction from lighting or power dreints
overcome by using a twisted three-conductor cable between stations.
an installation is greatly superior to the series system shown by FSgs. 43
and 44.
, Fig. 46 shows a series system in which one battery is used both for njgnal
mg and for talking. In tnis system the connections are alike at all stationa;
when the receiver nook, H, is down and the signaling key, U is up. there are
included in the line drouit only the vibrating oells. Deprnssing the steal-
ing key, U puts the battery in the line and causes all the bells to ring. It is
preferable to have the batteries so connected up that if two or more
tng ke3^ should be depressed at once the batteries will agree in polarity,
when the receiver hook is up the battery is connected in series with the
PBIVATB LIMEB.
1113
mumktttr ftnd the primary of the indaction oofl, while the skiiftliikc key
« md bells ftre thrown out of drcoit and the telephone receiver and aecondary
f tinding of the indaction coil are included in the line, aa shown at Station 3.
Ts. Jfk this, as in previous series systems, with the exception of Pig. 46, the
^Udng ourroit must flow through the signaling bells at idle stations. The
:4dvantage of the system is obviously that it eliminates half the batteries,
^tnly the one battery being used at each station for both signaling and talk-
no. 46. Series IVuty Byvtem Using One Battery at each Station for both
Talking and Signaling.
Ingj Am in all series systems where vibrating bells are used, the vibrators
niouJa be short-circuited on all bells except one.
The best method for connecting a large niunber of telephones on a single
lystem where onlv two line wires may be used is to bridge them, as shown
in Fig. 47. Tlxe dots A and A\ represent the binding-posta of each complete
>utfit. The bells are permanently bridged between the two line wires at
Stations 1, 2, and 4, irrespective o! the position of the receiver hooks. The
JtOm 47. Bridging Party-line Ssrstem; Three Arrangements of Station
Instruments.
ftgneto-generator is also bridged across the two line wires in an independ-
t oirouit, which is normally kept open either by a push-button, k, or
' mn automatic device on the magneto spindle.
At Station 3 the magneto-generator is bridged permanently across the
B HBin Stations 1, 2, and 3, but the bell is connected across only when the
«iver hook is down, being thrown out when the hook is up. At Station 5
» beil and generator are oridged across the line wires when the receiver
>Jc is down, and are cut out entirely when it is up. At all of the stations
liird bridging circuit includes the receiver and the secondary winding
tbe induction coil in series, this circuit being open when the receiver
ik. is down and closed when it is up. The hoox also closes the local
nsznitter circuit in the usual way when it is up and opens it when it is
m. The connections shown at Stations 3 and 5 possess the advantage of
ling ottt their signaling bells entirely when the receiver hooks are up.
end of leavins the bMBlb shunted across the line continuously, as is the
9 At Stations I, 2. and 8.
(
1114
TELEPHONY.
COHMOlf SKTVJRir XlVTK]iCOMM17VMCATn«
An intoroommunioAting Byatem may be defined as a system bavii^
or more telephones oonneoted to the same system of wiring in •aetia
that one may from any station call up and converse with any oilier
without requiring any central-station switchboard what«y«r. Ibi
munioating systems require one wire from each station to every other
and at least one more wire running through all the stations, wlkiere .
ing bells and one common ringing t>attery are employed, at least two _
w&es than there are stations are neoessarv. At each station th/^r« mwt
a switch of some kind whereby the telephone at each station may be
nected to any one of the wires belonging to the other stations. Intca
munioating systems are very practical and satisfactcnry up to llfteeik or
twenty stations ; beyond that, the large number of wires nmniiig ihnm^
all stations makes the cost of the system increase rapidly, eepeciaUy "whm
the stations are some distance apart. For a large number of sutttoos «d
scattered, a simple central-station switchboard system Is preferable.
FIr* 48 shows a very common but not a good method of intereoim<
number of telephones, where each station is equipped with ordinary
bells and magneto generators. Theoretically any number of telepf
be connected on such a system, but practiciu consideration would pi
limit at about twenty. In this figure there are four stations ; at ^
l.t
and 4 the telephone connections are drawn in full, while at Ko. 3 is
the telephone ouMt as it usually appears. There are four individual Itoi
wires, numbered 1, 2, 3, and 4, and a common return wire. Thus there k
one more wire than there are stations, and all these wires run throo^ ^
the stations, each wire being tapped at each station and not cut. At wk
station there is one ordinary telephone instrument consisting of Uieuflri
talking apparatus, magneto-generators and polarised bells. Below cacft
telephone there is an intercommunicatinff switch, the buttons of whldi tet
connected to the respective line wires, and the common return wire. Wl
not in use the switch at each station should remain on the home buttoe.
¥ •'
Fio. 48. Intercommunicating System, with Magneto SignaUiig
ators and Polarised Bells.
With all the levers In this position, a person at any station can caD vm
any other station by moving tne sAvitch lever to the button connected win
the individual line of the station desired, and turning the genento
handle ; onlv the bells at the home station and at the station called op wffl
ring. The ringing and talking currents pass through only the Instrvmeati
at the stations In communication. After finishing the conversatioa, ilit
switch lever at the home station must be retumw to its home poiltloiB,
otherwise the system will be crippled.
^
INTERCOMMUKIGATIKO SYSTEMS.
1115
Id
In Fig. 40 is shown a method of wiring the Intercommnnioatlng swltoh
that »yoids the prineipal ohjeotion mentioned in connection with Fis. 46,
that is, the failure to return the switch to the home position does not leare
the station so that it cannot be called up. OnlT four stations are shown,
but the system can be extended to include as large a number as may be
desirable. The usual telephone sets, consisting of a microphone trans-
mitter, induction coil, recefrer, hook switch, two cells of battery, a series
magneto-generator ana polarized bell, are included in the outfits indicated
by T,, Tf, etc The inside connections of these telephones are the same as
shown in the preceding figure.
^****** ^****'? ****i
FIO.49.
Xn Fig. 40 one bindlnff-poet of each telephone is connected to the common
return wire, and the other binding-post is connected to both the lever arm,
Sf and the Individual line wire belonging to that particular station.
The home button in this last system is the first on the left and is not con-
nected to anything : it is really a dummv button, but it should be there by
All means, for the lever, s, of the switch should always be returned to It
-when the original calling party leaves the telephone. If all switch arms, s,
are on the home buttons it will be found that the circuits of all instru-
ments are open and no bell will ring, no matter what generator is turned.
tf Station 2 desires to call Station 1 it will be necessary to first move the
switch arm, «, at Station 2 to button 1.
fig. 60 is a system similar to that shown in Fig. 40, but arranged for vi-
k>ra.ting bells and one common calling battery, CB, in place of magneto-
FiQ. 50. Ck>mmon Signaling-Battery System.
r
)
uia
TELEPHOmr.
Si»uox*k>ML «»d iiolariaed belb. A bAtterr U naed at aach stetlonfor<if«>
Ulu^ bha UttMNnitter. This ia probably the best arrangement of bMS«ia
tvi >UN'b ^ »^lam where Tibratiuff bells are used. This systecn requirasMi
luvuo vku^ iban that shown in Figs. 48 and 40 where magneto-oaillJiffif
(M^^fUtt •« Muployed; thus there are two more wires throughout thanttW
.Ki c ^b^«K^M•, The calling battery, CB, must be connected to the two viv
iCu'^Uv ^ut it may be located at any conyenient place. In thla arraBgHMrt
s^;u> ibk« bell at the stotion caUed will ring, the bell at the oaUlng itstta
wiM^uing silent. If the bells are not arranged in this manner, tosvikifr
Wi% vM« the two bells that happens to be connected in series when msktai^
v<m mttfbt interfere more or less with good ringing. Furthermore. It vow
ik4 <K> To short-circuit any of th6 vibrators, because there is no teUug vbia
|w^ stations may be connected together in making a call.
JAlL
3&
Fio. il. Common Signaling-Battery System.
Trouble is experienced with intercommunicating systems aimUar to thij
of Fig. 60 by reason of the user carelessly leaving the selective switch S^ot
the home button after using the telephone. Fig. 51 shows a method of vi^
ing such a system which obviates to a consioerable extent this tro«M«|
Here, the vibrating bell is permanently connected to the home buttoo,tfB
the pivot of the switch, 8, is connected to the arm of the pash-switehi a.
Any station can still be called up, no matter on what button iu switch,^
may Deleft.
F10.6S.
The same system of wiring employed In Fig. 48 is applied to the 07*^
shown in Fig. 62, in which magneto-generators, 6, andpolarlaed bell^C.
are used in place of the battery and vibratiuff beUs. There ia no n^^^
having a push button or automatic shunt on the generator, althou^ i^^
do no harm. The generator is norroallv on open circuit because one ofjtt
terminals is connected to the under contact of the push switch, K. InoivBr
to call up a station, the switch, S, is placed on the button belonging totM
station desired, the push switch, K, depressed, and the generator hsaaH
turned. Since no common battery is employed for ringing, this vj^*^
requires one leas wire through all the stations than the preceding airaog*'
ment.
INTEROOUXimiCATINa 8TSTBHS.
1117
ektf In Fig. 53 is shown an arrangement In irhloh one conveniently located
gfi eommon battery, G B, Bupplies current for ringing and also for ill trans-
(gs mitters. No matter wnere the lever of the eelective switch is left, the hell
0rvt cau still be rung, but conversation cannot be carried on until the switch at
:. the station callM is returned to the home button. This system Includes a
"^ piece of apparatus at each station that has not been required in anyof the
,r systems previously described, to>wit: the impedance coil B. Where a
l\ eommon battery supplies all the local microphone circuits with current In
systems of this Idna, there is very apt to be cross talk hetween two pairs of
telephones that may be in use at the same time, In which case the oattery
will be supplying current to four microphones.
tAtmr
Vfi I tTATWil 1
PL
OCMMCI* WTMIW>
• Y»
9*
uwt »
UM. »
•TATiei* »
Fig. 63. Common Battery System with Impedance Coils.
The cross talk is due to the variation in the fall of potential along the
battery and common return wires.
The cross talk may be greatly reduced by using batteries of very low in-
ternal resistance, such as storage cells, and making the common return
and battery wires extra large, that is, small in resistance, so that the vari-
able fall oz potential through the battery and in tiiese two wires may be
small. However, it is impractical to make the resistance of these two
wires low enough, especially where they are of considerable length, to
eliminate all cross talk.
Another way to reduce the trouble from cross talk Is to insert an impe-
dance coil in each microphone circuit, as shown in Fig. 63. This makes
the impedance of each microphone circuit large compared to that of the
two lines and battery, Mid in order to get the same current as before in
each microphone the e. m. f . of the battery must be increased. These im-
pedance coils reduce the efficiency of the system, but the reduction in
oroes talk compensates for this loss to a great extent.
— f-|
CMVlNNWr*
OMiWb««a.t
Pig. 54. Badial System ; Selective at One Station Only.
1118
TELBPHOKT.
It Bometimes ooonn that a syitem is required to be bo arranged tbAt
station oan call up any one of the others, bat the others can call up
oonverse with the nrst station only. Fig. 54 is a diagram of snch a sys
Station No. 1 or No. 2 can call up station C by merely depressing tbe
switch Kl or K2, but they cannot call up or converse with each
Station O by means of the switch, S, and push, K, can oall ap
Station No. 1 or No. 2. There are only two wires that must run throogh al
the stations. There is one wire, however, from Station C to each one of
the other stations. These wires, Call Wire No 1 and Gall Wire No. S,
used only when Station 0 calls up one of the other stations. On
could be made to answer if there was no objection to having all bat
home bell ring when Station G makes a call. In this case a certain n
ber of rings would be necessary for each station except C, and the .
common call wire would be connected to the signaling key at a. Station
and there would be no need of the switch, S.
As arranged In the diagram, the push switch, K, is normally open.
Station C desires to call Station No. 2, for instance, the switch, S, must
turned to button 2 and the push switch, K, depressed. The one eom
batterv, B, furnishes current for all ringing and talking. At each statkm
there is an ordinary receiver, microphone transmitter, and vibrating belL
There Is only one bell in circuit when a call is made so that each beu most
have a vibrator. It makes no difference upon what button the switch, S,
is left.
In the systems so far described there is nothing to prevent the intereetn-
munlcating switch from being left off the home button when the convmae
tion is ftnished and the receivers hung up.
Pia. 55. Ness Automatic Switch.
An example of a device obviating this trouble is the Ness automatte
switch, illustrated by Fig. 55. arranged so that the replacing of the re-
ceiver upon the hook causes the switch to fly back to its home poeitioa.
In the engraving S is the lever of the selective switch, adapted to be ro>
tated over the various contact buttons, 1, 2, 3, etc. It is mounted upon a
shaft. A, passing through the front board of the box and carrying a rmtchet-
wheei, £, Inside the box. This ratchet-wheel is held in any poalilon to
which it may be rotated by a pawl, F, and thus prevents the lever B, from
turning backward. Upon the short arm of the hook lever, H, is pivoted a
dog, Q, adapted, when the receiver is removed from the hook, to engage a
notch in the pawl, F; when the receiver is replaced, the dog, G, is pmled
upwards and lifts the pawl out of the engagement with the ratchet-wheel,
allowing a spiral spring around the shaft, A, to return the switch lever, S, to
the home button. Alter raising the pawl out of the notch on the ratehet-
wheel the dog slips out of the notch on the pawl, thus allowing the latter to
return into contact with the ratchet-wheel in order to be ready for the next
use of the telephone. In order, however, that the pawl may not engage the
ratchet-wheel Def ore the lever, S, has fully returned to its normal podtion,
t^TERCOMMlTNICATING SYSTSUS.
Vuemenl wllh Ihe ritMhet-wheel ontll the toUtlon of ths larar U oom-
.#M. A t till* point k pin on the f vtber ilde of the rmtohet-vhwl pmllM
• dog, J, out of enengenieDt with the V^-Pi ""i aUowi the p*«I, 7, to
l))i isio eontaot with the ntohet-nheel.
Inng.Mmreiho<
DD bitUenr, CB, t,
L DnllumrT TlbrMli
11. vbile thow -
-'illT or— -
imoD SlfOBllns BMMiy Bfetem; tndlTidiul Talking
oiTD the clraolts of > [oor-eUtloa ayatem uilnE one oom-
for ringing up the luion* (tkUoni, ewsh (tatlon harlng
bell, tf. The olronlta of Statloiu I ud 4 ue ehown In
■ itloOH, being oiaotly the (sine,
xnlltad. It wlU benol
(]
fia. 67. Sritein LaTing Common Talking and Signaling BatWry.
1120 TELEPHONY.
that etation which does bear the same nnmber In th« mmatnur ^
▼iously described, by means of the wire. e. In this eommoD^iatterT
system two additional wires are run, one t>eing termed the " call wire*
the other the " common talking wire." The oall wire and th« talkiu
are connected through the calling battery GB, as shown. It is erideat
the number of wires passing through all the stations will be two mo(«
the number of stations, irrespectiye of that number.
If Station 4 desires to call up Station 1, for example, No. 4 will tuts
switch lever until it rests upon button 1, then a slight pressure apoa
switch knob causes the switch lever, S, to touch the contact atripTDTtf
Dieting a circuit from the battery, CB, to contact strip, I>. 1«t«- Li
button, 1, at Station 4; line wire, 1, wire, d, switch, H, and bcA, C
Station 1, and back to the battery through the common talking v
When both subscribers remove their receivers from the hooka, the d
are completed over line wire 1 with the common talking wire as a i
At the dose of the conversation the receiver is simply hung upom the
and the automatic mechanical device returns the lever to Sie ~
sition.
Fig. 57 shows the application of the Ness automatic switch to kn isi
communicating system, using one common and centrally located battery
supplying both the ringing and talking current. The section. TB. o# w«r
battery supplies all the microphone transmitter circuits, and the wheat
battery, KB, supplies the current for ringing the ordinary vlbratiBc 1 ~
that are used in this system. In this arrangement it is evident ^t
number of wires passing through all the stations will in anT aiae of
be three in excess of the number of stations.
Tiro-^inikB iimiicoiianmcATKM « VBK.Kra«xB
By H. S. Wkbb.
By a two-wire intercommunioatin|( telephone systmn is meant one that
has two wires for each telephone station in addition to the two wirea used ■
common by ail the stations in some systems for signaling puipoees only.
The object of using two independent wires for each telephone staticm w t»
eliminate cross-talk.
In a single wire system if one wire in use by one pair of telq>hottc0 owi^
laps the wire in use by another pair of telephones, there is very apt to bt
more or less cross-talk.
This can be avoided by using for each conversation two indepoidcBtt
wires; that is, by using what is here termed a two-wire system. If tl*
wires for an intercommunicating system are run in cables, each pair most
be twisted together, as in telephone cables used in complete noetallic ex-
change svstems. If not in cable then the different pairs must be fairly wdl
se;>aratea, and if two pairs nm parallel to each other for any distanee tbs
wires should be properly transposed in order to eliminate cross-talk.
A two-wire system is shown diagrammatioally in Fig. 58. A contact
piece, e, is fastened to, but insulateofrom, the hook switch, in sucli a ntss*
ner as to close tha circuit between d and / when the telephone receiver reiu
on the hook. A double switch. S, is also required. The latter maybe mad*
in a variety of ways, but is here shown in a simple form in order that ite
connections may be clearly seen. The two levers m, and n, are me^uuiicdBy
fastened together so that moving one handle will move both levers ; b«a
the two levers must be insulated from each other; P is a simple poilh
button switch. One common and centrally located battery, RB, is need
for ringing the bell at any station.
To call up a station the switch, S, is turned until the straps, m and a, rest
on the buttons of the number of the station deaired and the posh-button
pressed. It makes no difference whether the receiver at the station where
the call originates is on or off the hook, nor is it necessary for the switch at
the station called to be at the first, or home, position. However, the leven.
m and n, at the station called, must rest on their home positions before any
conversation can be carried on. When ringing, only one wire of a pair a
used, the wire, V, serving as a common return; but when oonversins, both
wires of one pair are in use, and neither wire, Tr, nor V, is used; thus thers
J
INTEKCOMMTJNICATINQ SYSTEMS.
1121
a be no eross-ialk du« to induetion. The rinsiiig ourrent may cause
{ht trouble from tnduotion, as it traTeraee but one -wire of a pwr. By
atns of a doable contact push-button switch even the ringing ourrent can
made to flow through both wires of one pair and aU danger of induction
rubles be eliminated.
Fio. 58. Two-wire Telephone System.
ich an arrangement is shown in Fig. 50. The wiring at Station 1 is so
nged that the station can be called up from any station, no matter in
t poeition the intercommunicating switch St may have been left*
Fxa. 50. Two-wbe System with Automatic Switch.
rver, the wiring at this station has been purposely so arranged that
witch must be returned to the home position before anything can be
in the receiver.
(
1122 TELEPHONT.
When BUtoDUtla nrltebca an uHd tb> ivitcb ia kOtODiKtleatlT ratv^
ta the borne insitian when the recelviir la hungup. At StstioDSia f^^
the oooHHtiom im aleo niitkble tor uk with ma autoniMIe siriich.
If lar^Ho belli uul sotiermMn ne included In euh talnbone Ht iuUI^
of >D orriinuT vibrating bell, then the ringing batterv uicf tba tm iaxua
wir«e will nut be required, and the oonnectloni w"" ■"" *" '~
3'E
LB ihown ia Ht
■^ Pairs
Fra. eO. AutnmMia TalnplwD* ByMcm with HmgoMo Bda.
M. Thiian
At BUtion 1 ,
ia required tor ringing purpoeea, while the
double onntact Duih, P '. Tbe wliing tX
more evenly balanced gystem. but doeg not teau h> in n.iiii luum
over thai M Station 1. whieh ia the Ampler. At Station S i
oontaot pieoe on the under tide of tlie hook awiteh ia reqidrad.
rssa
^
USES OF BLBCTRICITY IN THE UNITED
STATES ARMY.
RsvifljiD BT Gbaham H. Powbll.
Tin OM of deetrioity 10 prevalent in nenriy every branoh of the military
t, being emplo3red in tlie operation of searonlictits, manipulation of coast
fense guofl, ammunition hoiatg; in range and poeition ftnden; for field
id fortreai telephones and telegraphs : for firing guns, submarine and sub-
rranean mines, and the control of dirigible torpedoes: while electrically
lernted ohronographs are utilised in the solution of ballistic problems.
In March, 1006, the President submitted to Congress ihe report of the
itional Coast Defense Board, appointed in the previous year to reeom-
md the annament, fixed and floating, mobile torpedoes, submarine mines,
d all other apidiances that may be necessary to complete the harbor de-
ise" of the United States and its insular possessions. Tliat board made
9 statement in its report that "Electricity nas become of vital importance
an efficient system of gun defense."
The foUowing were the general recommendations of that boaid so far as
etrical appliances are concerned:
I. That the electrical power for fortification and defense purposes be fur-
bed by an adequate steam-driven, direct-current producing central power
at, all machinery to conform in type to approved commercial standards.
t That each battery or group of battenes, depending upon local con-
ions, be equipped with direct-current generatons, gas or oil engine driven,
Called as a reserve to the central plant.
t. That searchlights, except such as are in dose proximity to the central
nt, be provided -mth and operated by self-contained units,
r. That the tor^o Msemates be eqmpped as heretofore with independent
rer for submanne-mine purposes, as an int^^ part of the subinarine-
le defense.
. That when alternating currents are essential, they should be obtained.
raoticablOj from direct current by means of a suitable converter; or, if
•e eoonomical, by a separate alternating unit.
. That the current from the fortification oentral plants, wh«i not needed
fortification service, may be used for garrison purposes when such distri-
on does not require too large an increase in the sise and number of units.
That if garrison service requires alternating current, this should be
>lied by the oentral plant, either throui^ a suitable converter or from
mating current units specially installed for the purpose in |the central
ion; such increase, however, and all additional cost due to post lighting
g a charge against the proper appropriation.
That uniformity of tsrpes and accessories is desirable.
That all electneal power plants for the use of fortifications shall be
ated by the Artillery.
irchlights are used both as olTensive and defensive auxiliaries; defen-
wlien used by shore fortifications to light channels or by a vessel to
•ver the approach of torpedo boats; offensive when used as " blinding,
s" to smotner the liffht of an approaching vessel and confuse her pilot,
e aooompanying illustrationB snow the searchlight manufactured by
ckert ft Co. of Nurnberg, Germany.
9 lamp fa placed on top of the two lowest longitudinal rods of the cas-
ind 1b held in place bv four lugs, two on each side. The carbon holders
I upward through a slit in the casing, and there is a small wheel in rear
loVins the light parallel to the axis of the reflector for the purpose of
Ing It. The trunnions of the casing are fastened to two longitudinal
■ ■" ■ lisof t ^'
1 what
1128
>n each side, parallel to the axis of the cylinder, and can be moved for-
OT back so that the casing and what is carried with it will have no pre-
(
1124 USES OF ELECTRIGITT IM UNITSD STATES ABHI
Fic. 1. SahDokert BAareMlght.
SEAKCHLIGHTS. 1125
ponderanoe. The tninnioiia are supported in trrmnion beds In the endx of
enpports which project upwards from the racer.
The elevating arc is attached to another longitudinal rod beneath the
cylindrical caeins and is capable of adjustment on this rod. Engaging in
tnis arc is a small gear attached to a horiiontal shaft passing thrpngh the
right trunnion support and carrying a small hand wheel. This small hand
wneel is for the purpose of elevating or depressins the light rapidly.
The light may be elevated or depressed slowly oy means of a small hand
wheel attached to another horizontal shaft in front of the one Just described.
This shaft near its center carries a worm, engaging in a worm wheel on a
rertic^ shaft, to which is also attached a bevel gear. This gear engages in
another, which is attached to the quick-motion shaft, but is free to turn
about it until it is connected with the elevating gear wheel by means of a
friction clamp. The relation between the worm and worm wheel is such
that a slow motion is obtained. *
The racer rests upon live rollers and fs joined by a pintle to the base ring.
Attached to the oase ring is a toothed circular rack, into which on the
outside a gear wheel attached to a vertical shaft engages. This vertical
•haft projects upward through the racer and carries a worm wheel, which
engages in a worm carried on a horiiontal shaft having a hand wheel. The
worm wheel is entirely independent of its vertical shaft, except when con-
nected with it by means of a friction clamp. When so connected, by turn-
ing the hand wheel the light is travorsea by a slow motion. To traverse
the light rapidly, the frietlon damp is released and the light turned by
hand, taking hold of the trunnion supports. One of the ends of the slow
motion elevating and traversing shafts is connected with a small electric-
motor, which is encased In a box on top of the racer. By means of these
motors the motion of the searchlight can be controlled fk^m a distant point.
A switch Is provided with contMts so arranged that the currcmt can be
passed into the armatures of the motors in eiwer direction, so as to obtain
any movement the operator may desire. The current needed for the move-
ment is obtained from the lines supplying the current used in the light
itself. The current Is brought to tne motors by means of contact points,
bearing on circular contact {Heces attached to the racer.
The reflector is a parabolic mirror embedded in asbestos in a cast-iron
frame, and is held In place by a number of brass springs. The frame of the
reflector is fastened to the overhanging rear ring of the casing with studs
and nuts, the overhanging part of the ring protecting the reflector from
moisture. In order to enable the operator to observe the position of the
carbons and the form of the crater while the apparatus is in use, small
optical projecton are arranged at the side and on top of the casing, which
enables images of the arc as seen from above and from the side to be
observed. When the light is properly focused the positive carbon reaches
a line on the glass on top of the casing.
There are two screws on the positive carbon holder which enable the end
of this carbon to be moved vertlcaUy or horizontally to bring it to a proper
adjustment.
In consequence of the ascending heat the carbons have a tendency to be
consumed on top : and to avoid this there is placed just back of the arc and
concentric with the positive carbon a centering segment of iron, attached to
the casing, which, becoming magnetic, so attracts the current as to equalize
the upwfl^ burning of the carbons. In taking the light out of the casing
this centering segment must be unfastened, and swung to the side on its
hinge.
An example of the method of calculating the intensity of the light sent out
by the mirror followi :
Diameter of parabolic mirror, 60.06 inches.
Diameter of positive carbon, 1.6 Inches.
Diameter of n^ative carbon, 1 inch.
Power consumM, 160 amperes x 60 volts.
Maximum intensity of rays Impinging upon the mirror, 67,000 candle-
power.
ATerage intensity of rays impinging upon mirror, 45,600 candleiwwer.
Diameter of crater, 0.005 incn.
Intensifying power of the mirror -^ — fooos)' —4,258.
UHES UV EL1K;TSICITY IB UNITED STATES AKMF.
Fio.a. DUgiwn ulioirliig Bowuhllght Oonneelton*.
DATA RBLATIYE TO SEARCHLIGHTS.
1127
'm af 'in OOOI tv
aowTOiwmui jo pie^
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i §
1128 nSBS OF Ba.BCTBICITT IN UNITED STATES AMXI.
. Ths IdckI diatmaoc of the mimr k &J
The diaperaioo ui(le of tha OBea-
Tha diunat ' -
«t a diMapoB of 1111 y»rda « 84 nnk.
Konat for ttu purpon of r^mktiia
□Hurx tb«iunp ■bould indicmtaahK
W^vDlti Tb« amueclioa ofihrS
•IcvMing uid trsvaraiiu ia - J?^jf!lJ*
Until raomtly tl» SwaT^JSS.
"rJtr^'^?!" th.tiSrin'SShffiJ
■t the Pwia Expoutioo of IftOO in tte
Airadn ds T«cn «t ds Har " whi^»
0 feet fl iDBhM in diamdw. uid btbi
bBim of 310.000,000 candl™. t£™
•IigWly UMMdttl by tbs ao-incli !>»>»■
tor of th« Qaoeral B«trio Oo. SlS
Lojuiana Porehaas EiixwitioD.
, The table on precadinc naan rrm
dau in nsard lo warehliiEta^^^aSS
In the eiHrjmeati
suiu. etc. it beaomaa ..„«rf «> ucer-
t^n the Tclositr of prnjaetilH, both
while PMsna throoth the bore of th,
KDn and dunn( flighl. Chroii^Ktuiilu <<
DTOiecUe d '^^^h v*>titr rJ a
taiT[eU are sH up in tiie aXDaa'^tba
Pffieotjle, canarally 100 fen .nart.
frame of wood oarryioB a nnmba- of
•mall pwaUel^pper wirta. Tha ivtmk-
■at inventsi by Cmo-
uin u Boulanc« of the BelciBn anU^
Ijry. which wu afterwardi T>wiJitii-| br
Captain Breger, '
mrent at the first frame and ■
laer; the Icft-hana magnet. :
rame, and eupporta an armati
rtrument depends foritaaeev-
tbe Law of Callinc bodi« or the
'" ^" ^ f ™Tity, nantely. 31
t eaoBiU of anitiealoohinui(Fic.3}
rbich are affixed two eleotroDiacnau:
"1
CHBONOOBAPHS.
1129
1m ehroDometer C ia a lone, cylindrieal br^as tube terminating at its
wr extremity in a piece of eoft iron, and bearing at its lower extremity a
A bob. It ie eurrounded by a nno or oopper eyunder called the recorder.
i ruptwe of tbe first target causes the demagnetisation of the magnet A,
anag the rod C The registrar Z> is of the same weight as the chronome-
ana is a tube with soft iron and bob. The cores of the electromagnets
the loft iron of the armatures terminate in cones slightly rounded at
ir vertices in order that the armatures when suspended can take a verti-
position.
Hien the registrar is set free by the rupture of the second target it
kes a horisontal plate (<0. which turns upon its axis (c) and releases the
ng id). The spring is furnished with a square knife («)» which strikes
recorder and leaves an indentation iroon it.
f tbe two ourr«»t8 be ruptured simultaneously the indentation is found
n the recorder at a height h, indicating that since the chronometer
tmenced to fall the time t has elapsed, i
->/f-
i is evident that f is the time required for the apparatus to operate; it
systematio retardation inherent in the instrument.
. special device, called the disjunctor, permits the simultaneous rupture
he circuits to be prodjioed, so that the time t is alwaiys known.
very simple device is resorted to in order to render it cointant. If the
ent of the registrar b not ruptured until after that of the chronometer,
if an interval T has elapsed between these ruptures, the time during
ah. the chronometer will fall before receiving the indentation of the
e will simply be augmented by I, and calling B the height of the inden-
>n, we will have
i+r
■•¥•
bus the detennination of an interval T always comprises two
s: the measuronent of the time (f) reoluired for tne instrument to
«te, and that of the time t-\-T. The dinerenoe of these two measure-
ts gives the time sought. This indirect method of ascertaining the
It is the eharaeteristie feature of the instrument and explains its accu-
-. When the rupture of the currents is produoed by the projectile the
ion (Z>) of the trajectory between the targets is regarded as rectilinear
the mean velooity F is D
F-
v/f(«-*)
Hh the time known that the projectile takes to pass between the two
ms, the velocity in feet per second, the usual mode of indicating, is
lly obtained.
10 arrangement of the circuit must vary according to eircumstanoes,
no partioular system can be preseribed. The genmd arrangement,
is shown in the sketch.
Fig. 4. Connections of Bouleng^ Chronograph.
1130 USES OF ELECTRICITY IK UNITED STATES ABMY.
SclisltB Cliraa
The Bouleogd ohronograpb measures velocity at one point only, bat it iij
frequently necessary to measure the velocity of the same piojee^ m
different points, as in determining the laws of the resistanee of Um air to jm
motion, or in ascertaining the veloeity of a projectile at daffeffent poiaia isi{
the bore of the gun.
Fia, 6. Sohulta Chronoacope.
For such purposes an instrument must be used which will prm a seals of
time of such length that all the phenomena may be registered i^ran it.
There are several instruments of this class, of which the best known is the
Schults chronosoope. In this instrument a drum (a), one meter in cireiiiB'
ferenoe, and covered with a coating of lamp-blaofc, is driven by the msaiM
of a clock movement and weight, so as to revolve once per aerond and
at the same time slowly advance longitudinally. In front of the drum,
mounted on a support and actuated by two magnets, is a standard tunias-
fork (c). vibrating 250 times a second: on one link of this iotk is a qniB (•)
which traces a line on the blackened surface of the drum, and theNidn
will record 250 complete vibrations for every revolution of the dnun.
A microscope with micrometer (not shown in drawing) is also attached to
the support fork: and each vibration of the fork, traced on the dnun in fonn
of a curve, can be subdivided in 1000 parts, thus allowing readings to bt
made to tri/^os o^ one second. On the support wHh the tuning-fork is s
small pointer which traces a straight line on the drum. This pointer has sa
electrical connection with an accurate chronometer which at crvery hsK
second closes the circuit and causes the pointer to make a sueoeesion of
records on the revolving drum. These marks serve as starting-points to
count the number of vibrat|pns of the tuning-fork, and to check them up
every half-seoond.
In order to measure the velocity of projectiles, the gun must be fitted
along its bore with special electrical circuit breakers, usually pWoed oat
foot apart. Each circuit breaker is so constructed that the curreot if
interrupted as the projectile passes, but is made a|^n before the projMUte
reaches the next breaker one foot further on.
These breakers, with appropriate battery, are all in one circuit with tht
primary of an induction coil. One terminal of the secondary of the eoil is
grounded to the frame of the chronoscope, while the other terminal cod
sists of a fine point near the blackened surface of the drum.
CHBOMOaSAPHS.
n tba primuy dnuit ii onocd by th* Bnt olreuit bnakar aloiic tb*
s of tb* (UO, the ipuk uulucad in the MintidHy of the inductioD ooil
ipa from tha points to the nvohrinc drum, IwTing ■ diillnet mark on
bUeluDed aurfBce. A> the next circuit bnakai in the gaa (g paasad
■pBrk agaia pinw to tbe dnun. and thil operatton la repeated lor every
■kanlDBgttiecuD bore. Thus on the dnmi, akniptde ot tbe Indieatjona
la by tfaa tualnE-tork, will be recordad a •uoDeaaaD of apot* at oertaia
«D«a from aacE other. The time elapeinc between any two of theee
La can be oalealated directly from the record which tb« tuninf-lork
le, ud thiuthe time (meaaured to the,,^ii part of aaeooatl) taken )»
projectile in pagaina a koowa diftanoe aloas the sun batral ealoulatad,
fUdriiol World and Engineer, June 23, IQOa
hi! ii a portable inatnunent, and while probably not ao acourata a* tb*
he chmnocraph ia oompoewl of the foUowinc ptiuoipal pafia (■•• Fisa.
Fia. A. ConnectioOB of Schmidt Chronosr^ih,
a balaooa-whaal ,d . with ita aprlnc and needle.
a •leetiomacnet B, which halda tbe balanc«-wh«l at tba atartinc-
ion and rehaaca it the initant the firat current ia broken.
• «lactRi>naan«t C, with ita meehaniam, which atopa the balance-wbee)
latant tha aeoond current ia broken,
fl dial D, Biaduated for T^odty resdinci.
lirEnlar frame £. for aettinc tbe inalrument at lero.
a button F, refetabiiflhiuE tba current in the macnet C
e rheoatata O asd O'. with their natitaace ooila for regolathic the
Ota.
' - ' ' etic metal. i> about 21 inohta in
licb ia beld by two atronfly made
- '-- itrument. The pivota of the
. _ _ „. ^.1 apring H ia faateaed to the
impoaed of two pane, »a abown fnFig. B. One part. a. of
Iriiidlyto the axia: tbe other, b. a iteel aprinc. ia faa-
' 'Ming Umited in its motion by two amall
USEB OF ELKCTKrCITT IN tJNITED STATES ABUT.
Fio. T. Interior Bshmidt Chronocnph.
il broken- ThiA nugDet ji Himev
placed tuicantially with reference to the
two Brrnktuna d. d'. placed opposite
Flo. 8. Conilrudion
mounted on (he btIi e, e', parallel to tb
■imilarly rupported. Tbe other eodi of iL-
Bprinc C. with its »diuittin«-Mrew. Set Id the ^^
pina. f, /, /'./'. that ordioBrily. due to the teuton of than-. _—,
the nm of tba baboce-vheeL boMins it fait. Wb« the e
^
CHROKOORAPHS. 1133
roach thit masnet, the armaturefl on tho kiren are »ttnoted by tho
re, the ipring ia elongated, and the premure of the pins upon the bamnoe-
teel IB renaaed. When the eurrent is Innolcen the annsturee are released.
d the tension of the sprinc eloaee the pins upon the wheeL To insure
Botive action the pins are aocuiately set ana the rim of the wheel is
Ued.
rhefaoe of the ehronograph is a graduated dial eonoentrio with the
lanoe>wheel axis. When the wheel is held at its 8tartinfE*point the needle
into at the sero of the graduation. The ecale in black indioates the time
tfaoutandths and two-ten-thousandths of a second. Another scale, in red.
es the velocity directly in meters per second when the screens are plaoea
meters apart.
rhe dial is covered with glass enclosed in the circular metal frame B,
;>in 0, fixed in the glass, is used to set the needle at sero by turning the
me, to which is al^ fastened the lens h, to facilitate reading. This lens
)rovfded with two pointers so placed that the reading is always taken in
\ vertical phme.
rhe button F is for the purpose of reestablishing the eumnt through
magnet C after it has once been broken. Pressing the button cloees
circuit; the magnet then attracts the armatures d, dr, fixed to the ends
bhe levers K, K7, This motion of the levers brings the small spring I,
unted on K', in contact with the projection A, thus forming a circuit,
ough which the current continues to flow after the pressure on F has
n released. This contact is broken by the motion of the lever when the
rent is interrupted by the shot. This arrangement prevents the current
n passing through the magnet and releasing the balance-wheel before
circuit is closed by pressing the button F. even though the broken screen
epaired, and gives the operator time to take the reading and prepare for
next shot. This is especially important when targets that ofeee the
uit automatically are used.
"he rheostats for regulating the currents are placed above the dial, their
rtance ooils being inside the ease. One binding-post of each rheostat is
irided with a circuit closer for passing the currents through the resist-
B coils or direetly into the rheostats.
his instrument was designed to overcome the minute errors inherent in
a* forms of chronographs, such as the inertia of the armature, the time
lired to magnetise iron, or in instruments employing a sparking de-
, the fact that successive sparks do not proceed from the same point by
itically the same path.
he agents employed in this instrument are light and electricity. Briefly
ad, a ray of light from an electric arc is reflected upon a revolving
x)graphic plate. The interposition of the shadow of a tuning-lork
8 on the plate a curve which is used as a scale of time.
I the path of the beam of white light is placed a Niool prism in order to
in a beam of plane polarised light. This prism is made of two crsrstals
oeland spar, which are cemented together oy Canada balsam in such a
as to obtain only a single beam of polarised light. The crystal is a
>ly refracting medium; that is. a light beam entering it is in f^eneral
led into two separate beams which are polarised and have different
siioDS. One of theee beams in the Niool prism is disposed of by total
Btion from the surface where the Canada balsam is located, and the
r emerges a completely polarized beam ready for use.
aeconcT Nicol pnsm exactly like the first is now placed in the path of
polarised beam. This second prism is called tte "analyser," and is
o that its plane is just perpendicular to that of the first prism, called
'polariser," so that all the light vibrations not sorted out by the one
a will be by the second. In this position, the planes being just perx>en-
ar to each other, the prisms are said to be "crossed," and an observer
Off ihiough the analyser finds the Ught totally extinguished as though
liter interrupted the beam.
' tnmixig the analyser ever so little from the crossed position, light
9s through it, and its intensity increases until the planes of the prisms
larallei. when it again diminishes ; and if one of the prisms is rotated
) will be darkness twice every revolution. In order to accomplish this
1134 USES OF ELECTRICITY IN UNITED STATES ABMT.
eikd without actually rotating the analyier, a traiki|>arent medii
whi<di oan rotate the plane of polaruation of the light mibjeet to the a^
trol of an electrio eurreat is plaoed between the two prisms. The »«*»<^«
used is oarbon bisulphide* oontained in a glass tube. To prodvee »
netie field in the carbon bisulphide, a coil of wire through which pM
electrio current, is wound around the glass tube. When the eurreat
the oarbon bisulphide instantly loses its rotatory power, and tha ray«tf
light is free to pass through the prisms.
Breaks in the current are made in the same way as in other IralliitTT
chronographs. This instrument is not now in use, but the fc
description is f^ven as showing the develo|mient of such devi4
complete desonption of this instrument, with an aooount of e«
see The Polaruina PhoU><!hranoQr«ph, Jtkn WUey dt Sont, New
MJkJnUPmLAXSOBr 4^9 COAftT-DBFBliSB C»TOS.
Until recently the carriages for the laiger caliber of guns w« . _
lated only by band-power, but tests having demonstrated the utility of
eleotric power for this purpose, such carnages are now etiuipped wiA
motors for the purpose.
In disappeanng oarriages of the type in use in the United Statea, the
operations to be performed are those of elevating and depressing, tn
and the retraction of the gun from the "in battery " position to that
after firing. This recoil position is normally obtained by the disc
the gun operating throi;^ recoil oylindera and a counterweight, the
being prinoipiUly for returning the gun to the firing poaitaon. Ho'
it is frequently aesirable, or necessary, to retract the gun without firing thi
piece, and for this purpose wire ropei are attached to hooks on the gaa
wvers near the trunnions of the /sun, the opposite ends winding on dnuns.
The electrical equipment consists of the following apparatus:
Traveraf efT Motor. — A 4 horse-power, totally enclosed motor, 110
volts, and having a speed of about o06 revolutions per minute. This
motor has a pinion upon its shaft which engages directly with »
the traversing crank shaft.
Blevtti^[»lieppeaeif mm^L lieinMiiMi M«i»v. — A si
motor is used for all of these operations. It is rated at 4 horso'^ioi
110 volts, and speed of 625 r.p.m.
A lever carries an idler gear so that the motor shaft may be thrown into
with either the gear on the retracting or that on the elevating crank abaft.
Both traversing and elevating motors are shunt wound, the fields being
energised directly from the switchboard and the armatures being operated
by individual controUers.
The two controllers, one for the traversing and one for the elevating-
retracting motor, are placed side by side on a frame bolted to the woikieg
platform m rear of the left standard of the carriage. Each controller slwxt
has a vertical extension reaching to a convenient height above the sigfatinc
platform from which the controllers may be operated if desired, tnou^
only one set of handles is provided, to avoid the possibility of attempts to
maneuver the carriage from two different points.
In the side and rear elevations (Figs. 0 and Oa) A is the rievating and
depressing hand*wheel, B the retracting hand-wheel, with lever C carryins
idler gear between them: D is the traversing crank shaft, S oontrolMa.
F controller extension shafts, O sighting platform, and a wire n>pe for
retracting.
The motors heretofore described are bolted to a bed plate inaide the
ehassls and inmiediately in rear of the hand wheels.
■I.BCX]ftIG F1J8SA.
It is often necessary to fire at a distance from the gun. as in experhnenta,
and for this purpose the electric fuse offers the safest, simplest. cheimMat sad
most effective means of firing high expfesives or laige charges of powder, and
the onl>r means of igniting separate charges simultaneously for greatir
.dwtructiveness, or a single charce from a distant point, or at a raiiuind
'-aent, or under water.
MAKIPULATION OF COAST-DEFENSB GUNS.
J
e elsetrie fuMi eonsina of tboul 1-ineh kncth of 6i
m stloy. 0.001 lo 0.003 inch diaowter, 1 oEid to 1 i
I the bride* vbioh ■■ lurrouiulKl by ■ little pin <
oed finv p&npomler for icnitiDsa powder ch^^ or
1136 USES OP BLECTRICITT IN UNITICD 8TATB8 ABUT.
Fut. Ob. Rtmr.
« firmLy tbfl Aulphur
bald« Hrmly in pUea the tuw wim. B ii Iba chunbar eontainiiw 30 lo M
gnina of lulminUe. A little gun cotton niimuDda (he bridce whieli u
Kldsred to ths buad endi ol tbe fUH «in* £>. The wine, * tolO fM* loi«.
have fottcn ooTen eoaked in AAphalt for otdinary outdooTi work uid pittft'
pergha ooverint lot aubcoaritie work.
1
DEFENSIVE MINES. 1137
o. 11. A. loimr tube; B, upper tube; C, plus of sulphur and glaae;
Z>, bridge legs ; B^ bridge ; F, gun ootton ; v, f uuninate ; H, fuse wires.
or end gkas, which holds fixed in plaoe the wire ends »nd bridge.
1 the fulminate is dry, the spaces in both parts are filled with dry pul-
snt gun cotton and tne parts are screwed together.
dine is a charge of explosiTe contained in a case which is moored be-
the surface of the water or buried beneath the soiL The mines laid
|Mrated in and around ■ea9oa8t fortifications are for the most part
nve in their character, fixed m position, and hidden,
sfensire mine Is either self-«eting, — a mine which, once placed, ceases
onder control, and is fired by means within Itself, mechanical or eleo-
,— or controlled, a mine fitted with electrical apparatus, which ena-
distant operator to ascertain its condition, and to fire it at any time ;
r also be fired automatically.
mtroUed mine may be fired in four different ways : (a) by contact with
tne only ; (6) at will of the operator only ; <c) by contact and wiU, both
leh are necessary ; (d) by obseryatlon from two stations.
»ntrolled sea mine may be either a buoyant mine whose case floats 8
let beneath the surface, and contains both the charge and electrical
ttUB, or a ground mine. The latter is in two parts: one a case contain-
e charge and fuse, rests on the bottom ; the other, containing the elec-
apparatuB, floats 3 or 4 feet beneath the surface.
>er wires lead to two or three Sampson-Leclanch^ cells, which are
oircult with the torpedo casemates ox the fortification.
Fio. 12. Electrical Land Mine.
sketch shows a self-acting electrical land mine, and Is self-ezplana-
By using three lead wires the mine may be flred by the enemy's con-
th it, or Dy the operator at the station.
1138 03BB OF ELECTBICITC IN UNITED STATKB AKVT,
DEFENSIVE MINES. 1139
. OlBOUXT CliOSBB IN TORPBDO. (866 Fig. 13.)
9, clnnilar permanent magnet with attached eleotromagneta N and S.
, armature whoee adjusting spring near K holds it away from the mag«
while a weak current flows In through the electromagnet oolls in a
ttlon to assist the permanent magnet. But If a stronger ouirant flows,
krmatnre is attracted, and sticks to the magnet, until a reverse current
St .in. The spring then draws the armature away, and breaks the oon-
oi the circuit closer K on W.
a brass ball f inch diameter, held by spiral 8.
a silk thread running through the vertical axis of the ball from adjust-
erew to the armature. When the vessel strikes the mine the brass ball
{ knocked sidewise pulls, by means of the string, the armature i^iainst
K>lcfl where it sticks.
JOOO-ohm resistance coil, which is cut out of the mine circuit by the
ftct of K on W.
;. priming-chacge.
OPEKATISG-BOX OJ5 SHOBS.
cells and brass bar.
and brass Imr.
Wf watching-batterv of gravity «
V, firing-battery of Sampson cells
, uringHDlug.
Mf, ordinary electro-magnet, 100 ohms. (See Belav No. 7.)
, armature pivoted at the center. (See Relay No. 7.)
spring holding armature back against a weak current. (Belay No. 7.)
snutter arm pivoted above its center of gravity. When set as in relay
1, shutter-arm 1/ makes electrical connection with the armature at N^ :
1 armature is attracted It releases i/, whose lower end strikes a bell, and
as electrical contact with the flring-bar at W,
terminal of mine circuit which may be plugged to WB^.
terminal for testing-set.
>, two reversing-keys.
md T are two stations, 1 to 8 miles apart, each having a key and an ob-
»r of the mine field.
Opsbation.
e torpedo having been planted and connected with its relay, whose
ier-arm 1/ is set as in relay No 1, a small steady watching-current flows
gh CK, WB' 6, MOI', H, N', J', C, V, coU 8, coil, N, W, K (1,000 ohms),
' again. The direction of the current is such As to preserve the mag-
m of the magnet. If the circuit closer is accidentally closed (indicate
shange of the resistance in the circuit) it can be opened by using the
sing-key from shore.
9 fuse F may be fired in four ways : —
Bff contact toitk the mine only. Insert firing-plug P'. When a vessel
M a mine the brass ball B in the circuit-closer is thrown aside, closing
W and thus short circuiting K. The watching-current, thus made
ger, flows from coil N through K, A, Z, fuse, G^y to Q'. Coming from
vj cells it cannot flre the fuse, but is strong enough to operate the relay
rop I/, whidh throws in the firing-battery. A strong current now flows
gh €K^ FB', P', W, J^ C, V, c<ai 8, coil N, W, K, A, Z, F, Q„ to CK'
, and flirea the fuse.
Ji will of operator only, who niayat any time drop the shutter arm 1/
ad and insert the firinff-plug. The flringHsurrent is strong enoush,
through B in the torpedo, to close K, short-circuiting R, and to fire
ise.
By eofUact vfith the mine and at operator* a UfUl. Remove firing-plug
lie watching^nrrent fiows as above in (a). When the vessel strikes
Ine 1/ drops, striking the bell, when the operator inserts P', throwing
flrtng-eurrent which fires the mine.
By oOBervation from two atatione ; shutter arm 1/ set, and firing-plug
When a hostile vessel appears over the mine from the positfen of X
leerver closes Ids key. X has like instructions. When both keys are
I the mainpart of the current from WB' flows throush €K, wB', fr,
H, Qf, X, T, O, to CK again, drops the shutter-arm and fires the mine.
obTious reasons the forwoing is not a description of the service cir-
toaer, but the principle of construction and ofMsratlon of the mines of
intrlee are much ^ke.
{
1140 UBES OF ELECTiUCiry IN UNITED 8TATBS ABHT.
. Uw IMOMMT)' oonuauMla to tht nin
d InCBDuity nas b«en ipcDt in deru «
(hnwh tha mediaca of printipc ukd dial tahKn(>hi.
praonoally tlu imiwnu method of mmimimimtinn
CDnuuBnd to another- Ai ordinary sommirdal talet
Comriiy ai.it doMsepawlCTabl* ana, the modccB ftirtififtion noMhot
Tba forte
battery eoDunandera, and tfaey ia tm
... ..__. ^ijj ,rtiaeB«*
Df primary oonBideration. Hi
the 8ini>[ Corpe.
rieia Vclenwfer. -
131 X 7 X 8t ineSm, vitb a
5|(^> 3
WirinsD
Q Field Induotion Telegnipta.
mil. the ratio betnea tha
ip«v(ed by means of an induatlc
Bondary wirinii beitig 100 lo 1. The muxnecio arouit w broken aif*
3 give inoreued apeed^ A polariaed relay ie used. The lino tatCaf
u tt three No. 6 dry oelli, pvinl 4i volu. Thie apparatus nita
juoceerfuUy for 250 lo 300 iiiil« over No. B ^vsniwd iron wire. fi|, »
efaowB (Jie oinniit.
n«la Tel«|»h«««. — Outfitie ooDUuMd in an oak eanyina oM.
( 10 iDcLo, and «
TwoN
FI«M Bnaaeii
idvtDt a biab-pitched note. Tdephone noeiver Is uMd tor ■□undcT
employed aa a teluraph iOBtrummt. Thie ia a very effident is '
operate. Has bew opentad o
ordioaty inslnuE
jne irf 30 miW o
bats iiii* lyiBf C
TELAUTOGRAPH. 1141
ground and praotioaUy short^rouited all the way; abo over 18 mileB vith
breaks in line totalinc 20 feet. The outfit is oontained in a leather oanTing
oese 10^ X 5i X 8i inohes, and weijEhs llpounda.
Telephone AwltclalMNardL — The Signal Corps also employs a
portable telephone switchboard, mounted on a tripod and weighing about 75
pounds. This has a capacity of 10 lines, cordless connection and magneto
call. It can be set up in a few minutes.
Wire. — Three different grades of wire are used. One form consists of
2 strands d steel and 1 of copoer, cotton covered, weighing about 12 pounds
to the mile, carried on reels of one^half mile. Another grade consists of 11
itrands of steel and 1 of copper, rubber covered and braided. This is capable
xf standing very rough usage. A third type of wire, but little used on ao-
K>unt of its weight, consists of 19 strands of steel and one of copper.
^
In the transmission of ranges and asimuths froA the observers, where
reat accuracy is required, the telautograph is largely employed. The fol-
»wing description of this instrument is tsjcen from ** Handbook for the Use
f Electricians," Government Printing Office, 1004.
lieacrlptlon, iPrlmciplea, and Operatlosi.
Tnuumltter. — By means of two light rods attached to the, trans-
it ting pencil near its point, the arbitrary motions of writing or drawing are
solved into simple rotative or oscillatory motions of two pivoted arms,
cated on either side of the writing platen. These arms are included in the
le circuits and carry at their extremities small contact rollers which move
and fro upon two rheostats, or resistance coils, these being so connected
rough the arms to the line and to the source of energy as to act both as
justable shunts and as rheostats in the line circuits, ay this method the
Ita^e supplied to the line is made to vary with the position of the pencil upon
writing platen, and definitely variable writinff currents are transmitted.
Receiver, — The receiver principle is equally simple. The variable line
rrents coming in over the line wires are lea through two vertically movable
Is, each suspended in a stroni; uniform magnetic field by a well-sweep
angement, from which they derive the name of "buckets."
Sacn coil is supplied with an adjustable retractile spring which tends to
x>8e the movement of the coil downward throu^^h the field. It is evident
t for given values of the line currents, each coil will have a definite position
ts respective magnetic field, depending upon the tension of its retractile
ictjgs. The vertical motions of tnese receiver " buckets," due, to the vary-
bne currents, are used to cause rotative motions in two pivoted arms,
ilar to those at the transmitter, which motions, through another system
:ght rods, compel the receiving pen to exactly reproduce the motions of
tranamitting pencil.
o aocomplish the x>«i-lifting at the receiver an automatic device is used,
astiofif of an induction coil at the transmitter, having two secondary
lingB and performing; the double function of pen-lifting and reducing
ion. The primary circuit of this coil is entirely local at the transmitter,
includes an interrupter and a shunt circuit controlled by the platen. ,
le vibratory secondary currents are superimposed upon the writing
mts, and serve to keep the receiving pen, in continual though impercep-
vxbnttton, reducing friction in, the moving parts, to a minimum. The
lal writincT pressure of the pencil, upon the transmitter platen opens the
t oircuit and causes an increase in the stretysth of the secondary vibra-
. Thia operates a vibratory relay inserted m one of the line drouits at
eoeivBT, opens a local circuit, and causes the armature of the pen-lifting
let to be released and the pen is allowed to rest upon the paper.
!iine the transmitting pencil from the platen decreases the strength
9 Vibrations, closes the local receiver circuit, and the pen-lifting magnet
eta its armature and raises the pen clear of the paper,
e shifting of the paper at the transmitter is done mechanically by
a of the master switch. The same motion of the switch operates an
■oxnaccnetio device over one of the line wires, which automatically and
Vely alufts the paper at the receiver a corresponding amount.
1142 nBES OP ELBCTHICITT IN DNITED STATES ABUT.
Theti
pen u madB
■ (all ben mi
^
TELAUTOGRAPH. 1143
lififld M to maka perfect linee ngardleeB of the cUreetloii of motion, and
fcble of hokUiifl^ an am|>le eunply of ink.
be inldnf devioe ooneiste of a bottle or eupply well, with a hole and
iper for refilling, and alflo with a second small nob in the side of the well.
I hole ii below the surfaoe of the ink, and the top of the well beins eorked
airtight, the ink is prevented from £k>wing out by the pressure of the
mal atmosphere.
be small hole is located at the unison point, and whenever the paper is
;ed the pen returns to this position and automatically^ dips its pomt into
ink which etands at the mouth of the hole. Capillary attraction is
dent to completely fill the pen, and, resting in the hoto as it does, the
t does not elog up with dry mk when not in use, but is always ready to
i writing with a full fresh supply.
SxplABAtion of IHsfTaai. (Vic* ^Uft*)
Tinaenslttor.— The motions of the transmitting pencils! are oonveyed
ilgh the pencil arms BB*. and pencil arm levers CC to contact arms
, which carry contact rollers BE\ these contact rollers bearing upon
|)eriphery of rheostats FF\ the terminals of theee rheostats being con-
sd through master switch O to the jwsitive and negative polee of a
J}le source of electrical enei^, indicated by batten^ H. The con-
arm ly is connected to the n^t line through one of the eecondjuiee
le induetiMi ooil /. and through the ri|dit-lme contacts O* of master
sh, whsn the master switch is m the wnting position as shown. The
act arm D is connected to the left line through the other seoondaryof
nductaon coil /, through the left line contacts 02 of master switch. The
prunary
ooil / and battery H, and rapidly vibratee, the current passing through
>rimary of the iiuiuotion coil, thus causing a vibratory current to trav-
the right and left line wires, the strength of this vibratory current
nding upon the position of the platen /; when this platen is depressed
le pencil in the act of writing the shunt around the primary of induc-
oou / is open, consequently the strength of the vibratory currents on
a inereasea; this incroBeed strength of vibratbn actuates the pen-lifting
m (in receiver). The paper at the transmitter is shifted by moving
andM N of lever O, which is connected to shaft P, which carries the pawl
gaging the ratchet wheel It, mounted on shaft of pi4>er-ehifter roller S.
movement of this handle N to and fro causes the roller 8 to rotate,
1 movce the paper forward. The shaft P also carries master-switch
vet plates Q^ Ul, 02, which open and close the line and battery circuits,
ding to the position of handle N; circuits being cloeed and instrument
ulinc position when handle N rests in position shown by arrow. The
ment of the handle N in the oppoeite direction cuts the instrument out
Duii. The handle is locked in either position by lever P, and cannot
leased except by pressing point of pencil A on button T, A signal-
Ik push button is shown at u; this switch when operated throws current
litive polarity through right line, which rings receiver bell, u, as here-
deeerioed.
ReceiTttr. — ^ The motions of receiver pen a are caused to duplicate
otions of transmitting pencil A through the pen arms h9/. pen-arm levers
hieh are mounted on shafts carrying sectors dd\ Light metal bands
» attached to the peripheries of sectors dd' and carry at their lower ends
[or "buekets") ff, and their upper ends are attached to springs mK.
>i]a ff* are movable in the annular spaces between the poles ox the mag-
and t, and h' end t^ Coil / is in circuit with Morse relay j and the left
ad coil /' is in circuit with pen-lifting relay m and the right line. As
mnsmitung pencil is moved its motions are transmitted to contact
SB', the strength of current on line is varied, the currents becoming
«r ae the rollers approach the positive ends of the rheoetate FF\ these
kte iraTeming line and passing through coils ff. causing them to take
nt poaitions in the magnetio fields, opposing the pulls of the sprinfrs
eee eprings being so adjusted tlMvt the positbn of the receiving pea m
■Hanf field will dways be the same as the position of the transmitting
on ita writing platen.
1141 USES OF ELECTRlcrrr IN UNITED STATES ABMT.
8- Tbs dcpnuKO of pUtao J, Buaisf ■
em line, musg the ■imstun of pta-Uhing ■»■
tha dreuit of pen-lifter m', thiu ndeuinc th(
lomdnf the Doi-anii nM ra ■■ ui lOlo* tba v
Fio. 10. TelButocra[>h.
tarreumnt will be weakaned. the annatun of poi-liftuic ralar M MaMiW
vibnte. dcMte the dreuH □! paq-lifler m'. whiota Bttnote it* knnuure Nd
thu« lidi the pm Iram the paper.
4. Tbe tiaper4bift«r <i' u an eleotronaatfoetie derioe and *- ~»-*--a^
bv the Hone relay ]'. tba annatiire of thla relay elonns tlw a
uiftar throu(fa iti fantard contact whto tba iwlu' I >■ •nwvaad
rent throusb the macter ■witoh by tbe m ■■-<.■-
1
WUUCLESS TBLEQRAPHT. 1145
5. The ncnal bell u. which is of low resistance, is thrown in parallel with
he right-line ooil, or '* bucket " ft when no current is passing through the
•pernilufter. consequently when signatinc current passes over right line
he bulk of toe current passes through the oell, rather than throujih coil /'.
A. The ink well (anonlinary glass bottle) is shown at d. the receiver pen a
Dtering the opening 3/ and receiving a fresh suppler of ink every time the
■per is shifted, the pen resting in this opening and in eontaot with the ink
hen the instrument b not in use.
iMtalllaff.
The instruments are furnished with a suitable backboard. theeoBnaetions
nng made between the instruments and the circuits on the backboard by
itomatio contact pins, so that the instruments can be put on and taken
f readily. The terminals on the backboard for connecting to line and
(ttery are plainly marked so that the proper connections may be easily
ide.
1. Vo wiit«. — Depress button with pencil point and pull lever towards
u a full stroke; release button with lever in this poaition, and write with
m pressure on paper.
2. T« sklfl Mipvr. — Depress button, holding it down until you have
»ved lever back and forth its full stroke as many times as you wish to
ft paper, then release button with lever in position towards you.
t. Vo li»Mir VP* — Dmress button, allowing lever to rest m position
sy from you. Always, after writing, leave the wver in position from you.
Care of Mmmtrwam^mim*
lie eare of the instruments consists mainly in keeping the ink bottles
perly filled with the ink which is supplied for that purpose, the occasional
ining of the pen points, and the insertion of fresh rolu of paper which is
plied for thai purpose.
he wirdess tdegraph outfits used in the Annv have been developed by
Stgnal Corps, and embody some of the best features of other systems.
oTtho most effective outfits is that designed to be carried on pack mules,
this purpose it is divided into three loads, each weighing approximately
pounds, the transmitting and receiving apparatus, the batteries, and the
I far afciai wires.
le transmitting and receiving apparatus is contained in a leatheroid trunk
*17 X 14 inches inside measurement. Fig. 17 shows the wiring arrang»-
t. Current is furnished from storage batteries or by hand generator,
itorage battery consists of 8 cells ci about 50 amp.-hour capacity. The
of the induction ooil is about 1 to 200. About 16 volts are required in
primary. Tlie key ia an ordinary open circuit key with extra large
mun oontaot points. A special double head telephone receiver is used.
tvpes of deteetors are employed, eleetrolytic ana silicon. The dectro-
deteotor is similar to that used commerciaDy, but differs in design.
lilioon detector is that invented by O. W. Pickard in which the action,
irmo-eleotric, and is in form of a brass contact resting on the silicon
U, which is embedded in a brass cup.
B allrial -wires are supported on a jointed pole 00 feet in height. The
B hollow and is made of spruce in 9 sections, 6 feet 8 inches long and 2^
■ m diameter. The atrial consists of 6 umbrrila wires, 85 feet long, and
aterpoise wires. 75 feet kmg. The counterpoise is used in preference to
d. The aerial wires are lormed of 42 strands of No. 33 phosphor
e twisted around a hemp center. They have a tensile strength of 300
Lb and ^^ele^ about 7 pounds per thousand feet.
;h a similar station receiving; this outfit fasa been successfully operated
k distanoe of 27 miles.
as are sometimes used for supporting the a&ial wires, and with the
thus obtainable messages have been received over 800 miles.
til wireless telMraph outfits have been made, wughing approximately
mds* csapable of covering 3 or 4 miles.
r
1146 USES OF ELECTRICITY IN UNITKD STATES ASm.
Sia. 17. Fidd Wirelna 8et-PMk. Tnink Typx ^iriii« Diacnm.
ELECTRIC AHUUNITION HUIST.
„ __, la CUB [xaitioi —
It ii ippJiod lo two platfoiini, Q Q, Fl(. 18, sithv of Hhidi u drsvn
pnid, whila tha otbar dwaada, by ■ winch driTen bya motor Uvoofk
xmn or Inin ■ear. A 5-l»n»-pi>VH' motor fmn nuiv S.OOO poonda oomitai^
eiglilad brOOO pound* of tba other plaUonn at themtaof 1 foot paraaooad.
he daaifo ii aimple, InexpeikBiTa, uid tba motor and bout arc fairky watt
1. tf 1( tba motor with both lerieg and ahuat fieldg. Iba Uttar baiu
Bittad whoi tiS la oloasd. &9 la ■ throe-pole reranins awlteb ahowD in
^tlnn hr tha risht-baiKl phUbrm lo aagsid.
troUer haa a ftartinc rheoatat, Rh; a hand lever, W: s iDrina
' ' ' ' isa^ ZfZ.,- and aa ovaclowl wleaat, Olh Tha
A
Fm. la AminuiiHion Hotat.
net VL dspvidi for Iti exoitatloti upon the Tottage of the motor tafmi-
Bod also upoa the integrity of ita circuit at any one of the four poinla
as. E. or F. The roaia circuit (rom ^f3 ia itrough the electromM-
I brske BB. seriee Gelde OL. to Iha oontacl piece b when the le«r V
Id down by UL masnet. th« circuit in cloerd fmm i> through d. V. W,
JT dlnot mftv the motor hs« attsitifd full in«ed), to RS. U U> US.
The nuin eireuit is broken either whpn the levBr V ii releued (e and
iiW the Bp«rk), or when Wis moved to the left (t and 1 taking tl
c). Tlie fever 7, when released by UL. is carried to the right by tl
S St ita Bxia until it atrik™ IP. The rheostat " "-- '-'----■
mf tho motor ooutinijoualy at difTenmt epwda,
o be In tlie eireuit longer than thirty aeoonda.
S Sa » bahy switch heU open by a epring. Ita object is to close, if
kJ. tba UJ. inacnet oircuil when open at E at F.
A and 4 are the deriMa lot sutomatical^ breaking the circuit through
tod thus tbe m»in eireuit when the platiorm ascanding ttrikn the luc
iob \m ■djOitaUe od the b«r aliding m guides h. On tb« tower end of
(
U4d UsySS^ OF ELECTRICITY IN UNITED STATES ABMT.
tlM» b«r an inaukM* copper wedse makes, when down, contact bciwoen \m
vvik|>er Uf niabat Mot F, and Iwei^ it wh«i up, thus *"«^M'^ vr
thi« cu«HU» tWvuch UIh B and F are alike and adjustable
6. VW rijikt'>hand platform is at its upper level, the left-hand is at di
(v>^«; vW Circuit through armature M has been bronn aod V is «ip ,
4'. U iftow we Xxy to start the motor without reversing RS. tJke
vhtuMsk .V will still be open at B. But throw AS down and the
UuviM VL will be doeed at F, and the left-hand platform can be raised.
7. TU start the motor at all, W must always be bioui^t iq> to tiis ML
■Wsfc^JM ^* before it until held by the underload naacnet UL, tiien W nv
S^ «M»r«d to the right, closing tluB circuit first through Rh and at bst wilk-
vM it*
^ When the left-hand platform, on nearly reaching its opper level
tswagss 0 and opens F, the main circuit will be opened at h mMifitb» molor
WMSIop.
Ik If it is necesoofy to move the platform farther up after the eiresit
Was bewi broken at E or F, the switch S may be closed and the pla^oni
may th«i be moved by the motor. So long as 5 is dosed V vrill not be
released except for no voltage or overload.
10. The motor may be slowed down or even stopped by moving W to
the leftjprovided Rh is large enough to carry the current.
11. The electronuurnetio brake on the gear wheel next the motor anus-
ture automatically ouunps it whenever the main current oeaaes and tbe
motor stops. It gives a auick stop for heavy or light loads.
12. If the electric maeninery is disabled the motor is quickly thrown ooi
and the platform can still be raised by a crank handle and gearing.
Electric night sights for rapid fire guns consist of a fitting and tiem
which can be inserted in the front sight bracket in place of the bead si^t
used in dasrlij^t. This fitting receives an encased white electric light
which illuminates a glass cone set under a pierced cap, so that the point (^
the oone only is visible as a bead to be used in aiming. The lirht proper
is shipped into a holder and down over two plugpins to the other end of
which the cable wires are soldered (Fig. 19). The rear edge of the rear
Fio. 10. Front Eleetrio light and Plug Conneotknw.
sight ring is grooved and the groove baked full of scarlet enamel, which is
illuminated by an encased red electric light, fitted similarly to the ftt>nt
light. Power is obtained from a battery consisting of ten O.K. dry oelb.
No. 4, If by 2k by 5| inches hijgh. Four ee^s are connected in series tnro«gli
a rheostat to each lamp, a fifth cell in each case being held in leeeivtt to put
into the circuit when the four cells fail to give proper light.
For use at night, range finders are equippeci with lights for UluminatiiV
the cross-wires of the instrument. The illuminating deviee consists of t«o
small electric lamps in sockets attached to the rear, or ejre-^ieoe, end of tbs
telescope, the beam of light from each lamp being reflected on the croflfr'
wires by two small mica mirrors. The lamps are i^proximately i ca
and 4 volts. Power is obtained from the main lighting circuits throqgn
suitable resistanoe.
FIRING HECHANIBH FOR DAPID FIRE OUN8. 1149
nMine mec^aitish ram mapxd ma oirna.
The elMtri<«l cairer for firliw rapid Ore (unz ii ohtBined fram two O.K.
IT tatteria, ash Bonsuting of ewht cellg in lerln. Thve bsttsrin v*
i( lUBd limulUuieaualy, but oiu ii kcft far uh in cue the other ihouU
iL Each butery ii itowed in a oorend box, carried in bracketi bolted
tb* aicii huH* of tbe gun cwrian. A third box ii ■imilai'ly carried for
j'ini tba alMniative BriDc cable. The battery cwried on the left u
Jinarily iukI to fire thepieee through the piMol eomiaatian. while the
eoDtberiflitlimedviththaaltdmatiTeariiwkey.
ODetemiiDalaleach battery u attacked br a short cable to the framaot
> caniac* u an eartb namiMitlaD. The othv lermiDal of the battcfrou
rft aide of tha hame 1> eonnected by a cmble 4 (eet lone with tbe front
lenniler tbepii«olCFi|a.31an(l 22). Whan the trinerta polled tha cir-
ia oompletad to tbe rear nipple, from which a al>le7S (eet fi inches Idu,
Of under the cradle ana through a twieted boolc to tbe right side
BCta with tha contact surface plug. This is bracketed to the cradie in
, -- a into "battery" .
lOt pin, preaeed out by a spring in the contact-pin plug, attached to
at the plug before mentioned. The connection for the next shot is
im the contact-pin plug the Hrinc-pin cable siteads thniush a locking
: the hiuKS of the breech mechanum to the firing pin. the last 10 inches
armorad for protection (Fig. 22). To enable the euinoneer who
:ha piece to aecertaiD whether tbe bteech block is entirely closed and
mneotlona otherwise complete, a busier is incased with the pistol,
SO) so that when the button over the triager is pressed b)^ tba thumb
uit fa oompleted through a reeistaace wilTwhicb perrnita just enough
■t on for an instant only. The ear must behekl ckiae to tbe buuar
i
r
1150 USES OP ELECTRICITY IK UNITED STATES ABHI
I I ,
PtRlNO MECHANISM FOR RAPID MRE GUNS. UM
BUcttbeHniHl. Wlum tlw triner !■ pnllBl,B dirtoteinnit ia nmpMad.
nittiacttw hill mmBt bom tM bWury to pMalhrouchtbcprtmar, thu*
and the pMoI liH«d oM of lU dot. The nufMC-eoDtaet plan an than
soaeoted by withdrawinc the locking pinn whjch enwevith bayonet
■ in the contKflt-pluf block, kfter wbich KODlber piatol uid cables loay
pplied or the altemative liriDC key and cebln ueed. . 1
I tbe alternative battery, in the Cmnt box on the ri^ht lide ol the Irame. M
other tenuioal ii dinctly soiuiected *itb the flrinc pin thnnish the fl
Vn. as. Altnnatlve Plrinc Key and CablM.
11,8 teat bmc The leoath of th«M
-, : ..» kay may be taken under the pleee to the Wt lide
— d by the eaanoneer wb^ia aimins.
B aH«rnatnB lay (Fia. 33) conaiMa of a tuba into one and ol vhich a
aodia eoupled laat. ^be cable enterina tbe other end ia aecurad to a
«r wfaioh la held oat by a ooilad aprins. When ccaqwd in the band
1162 USBS OF ELKCTRICITT IN DNITED STATES ABUT
with tba thumb on ^ pliucwm^ the imble ind^nuy ba V^jb^ U^tM
sompMiaB tba olrcuit. To gaarJ t
piCM. > vlit kw i* wirw* to tbi» firinL — — ,--,. — _
at tha pliiD«r. mad tbb i> kept p(uh« under tin plunnr hmd imli tk
piMia ii about tfl be find. FigB- 31 ud 23aboirthe coiuwctkuu ferbotl
night ■ichu*ndfiriii«einiuita,aixl Fig.MKinadM*il>orthe '
« IhTph
ELECTRICITY IN THE UNITED STATES
NAVY.
w
fiBYlBED BY J. J. G&AJ3X.
A.T the present time (January, 1908) the standard practice on ships of the
dted States Navy is to use direct current, at 126 volts, distributed on
) two-wire system. Previous to 1902 the standard was 80 volts, conso-
sntly many vessels have apparatus of that voltage.
L ship's installation is conveniently divided into dynamo room, lighting
tern, power system, and interior communication system. The wiring of
sh sytitem is kept entirely separate from the other.
?he dynamo room contains the generating sets, main switchboard, and
aetimes condensers for the engines.
*he lighting system supplies all ship's lights, searchlights, and signal
tits. These are installed in two separate systems called "Battle Service "
1 *' Lighting Service.*' Battle service comprises all lights necessary dur-
actiou, and these llshts are arranged so as to be invisible to the enemv.
^ttng service comprises the additional lights necessary for ordinary hao-
bion.
'he power system supplies the various electric auxiliary machinery which
f resent conshits of all ammunition hoists, turret turning gear, elevating
ramming gear for the larger guns, boat cranes, deck winches, ventilat-
fans, water-tight doors, and motors for driving line shafting in laundry
I engineer's workshop. Anchor handling gear and steering gear are at
iseut always steam driven, but electric devices are being experimented
h. Tho auxiliaries in the engine and boiler rooms, consisting of numer-
i pumps and the forced draft fans, are all steam driven, except In a few
ftels not yet linished where electric forced draft fans are being installed,
'he interior communication system consists of various devices for trans-
iting signals and orders from one part of the ship to another. Most of
se are electric, but in some cases they are paralleled by mechanical
livalents, as, for example, voice tubes paralleling telephones.
DYIf AMO nOOM.
he generating plant is located In a compartment called the ** Dynamo
)m,'' which is under the protective deck and adjacent to the boiler
ms (when practicable), so as to secure a direct lead of steam pipes.
dfiMKAATIirCMIKTS.
he followitijg are the principal requirements contained in the standard
oiflcations for reciprocating generating-sets :
aoh set to consist of an electric generator direct-coupled to a steam
ine, both mounted on a common bedplate.
he sols as a whole shall be as compact and light as is consistent with a
> r^ard to strength, durability, and efficlencv. The standard sixes, with
Ir corresponding maximum allowable speeds, weights, and over-all di-
isions are :
!ize in
Revolutions
Weight in
Length in
inciies.
Width in
Heiffht in
inches.
lo watts.
per minute.
pounds.
inches.
2Z
800
660
32
20
30
6
750
1,900
60
28
40
8
660
2,600
64
34
60
16
460
6,G00
78
40
60
24
400
7,300
88
48
68
32
400
10,000
101
62
78
60
400
16,000
110
00
85
100
360
22.000
126
70
95
1153
1154 KLBOTBICITY IN THB UKITBD 8TATS8 NATY.
The dMign iliall proride for aoeeBsibllity to all parts requiring ii
during operation, or adiuatment when under repair. Sets arQ tooe
to operate right-handed, i.e., counter clockwise when facing the ccmbhiWh
end, or left-handed, as required. The design to be preferably unch tliat
same parts may be used in each, in order to avoid iiiorease In nai&ber.
The sets must be capable of running without undue noise.
wear, or heating. Must oe balanced and run true at all loads, up to 3S||Mt
eent abore ratins ; must be capable of running for long periods under nfl
load and without eontinued attention.
Cast or wrought iron shall not be used for bearing snrfkoea, exeepk b
cases of cylinders. yaWe chests, and crosshead slides. Both upper aai
lower halyes of main bearings to be remoyable without removal or ms^lae*'
ment of shaft.
The driving shaft must be fitted with thrust collars or other suitable de>
vice which will prevent a movement of the shaft in the direction of iii
length, as might be caused by the rolling of the ship.
The combination bedplate to be a substantial casting, and provided wtth
accurately spaced drilled holes for securing to foundation.
An oil groove of ample width and depth to be cast in the npper flaaae of
bedplate, to be continuous around the engine, and to be provided with a
stopcock for drainage. The lower side of the combination bedplate te be
planed perpendicular to the line of stroke of engine.
Seats for all bolt heads and nuts to be faced. All nuts to be case hardened,
and to be U. 8. standard sizes. Where liable to work loose from TibratfoB,
nuts are to be secured by use of ]am nuts and spring cotters. All bolt
to be neatly finished.
The two halves of the main coupling to be either keyed to or forged _.
with the engine crank and armature shaft. The coupling to be bolted
gether by well-fitted bolts, driving to be done by a cross key set in tts
faces.
Adjoining portions of the machinery shall be given corresponding maiki
whenever tnu may be desirable for insuring correct assembly.
luterohangeablllty among the different sets and their spare parte, of As
same slie and make, as furnished in any one contract, is requlnd. This to
be demonstrated as part of the final test for acceptance.
Engines are to be of the automatic cut-off vertical eneloaed type, <
to sun condensing with maximum practical efliclency at au loeda,^bat
capable of satisfactory operation when running noncondensing, to i»e of
sufficient Indicated horse-power to drive the generator for an extended ttne
at the rated speed, when said generator is carrying a one-third overload.
Sizes 2| K. W., 6 K. W., ana 8 K. W. to be simple engine, single or twin
cylinder at the option of the contractor. Sixes of 16 K. w . and above to bs
crossHsompound with cranks set at 180^.
The normal steam pressure under which the engine, running eondenstiv
with 26-inch vacuum, for different size sets, is to operate, and the maxiBiuB
allowable water consumption per K. W. hour output of ueset are :
•
K.W.
Normal steam
pressure.
Water ooosnmptloB
per K. W. hoar.
f uU load.
8.6
100
106
6
100
90
8
100
65
16
100
44
94
100
40
62
100
97
60
100
88.6
60
160
88.S
100
160
91
SKGiirB. 1165
la l6itlBfff aoRMtloos than be made Inr ealorfmeter for entrained melt-
re. Baperheatinc f ball not be need in tne teet.
Snginet matt run unootbly and f nmiab tbe required power for full load
anv iteaiii preMnre wltbin 90 per cent (aboye or below) of tboee giren in
I aoore tablejiand ezbanating to oondeneer at 25 Inobes Tacuttm ; to f ur-
b power for IN) per eent of ful load at steam preesnre 90 per oent below
rmal, and for fall load at any steam preaenre between normal and 90 per
it aboTe normal, wben ezbaotting witb tbe atmospbere. Mnet be able to
ur without injorr tbe sudden throwing on or off of one and one-lJiird
les the rated full load of tbe generator, by "**^'"g and breaking tbe
leralor's external eirouit.
?o be so designed tbi^t tbe work done by eaeb cylinder, as shown by indi-
or eards, will be as nearly equal as praetieabie under all ecmditums of
d. Indicator motions must be proTided which will accurately reproduce
t motion of the pistons at all points of tbe stroke. This will require, for
se-compoond engines, the operation of the reducing motion for each
Inder from tbe orossbead or other moTlngpart belonging to that cylinder,
ndioator pt||>ing to be installed in a manner to secure accuracy of indl-
or cards. Connections to be made at each end of each cylinder, and
ed to a three-waj cock In order that one indicator may be used for both
id and crank encu of cylinder. Connections are to fit the standard indi-
ors of the Bureau of Equipment.
be length of stroke of the engine to be not less than the diameter of the
e of the bii^iipressure cylinder.
lie cylinders to be made of hard, close-grained chareoal iron, bored and
ned true, of sufficient thickness for operation after reboring once, steam
I eadiaust ports to be short, of ample area and ftree from fins, scales,
d, etc. Cylinders to be fitted with tbe usual drain cooks, all drains to
i in one outlet. In addition to these drains, relief Tslycs are to be fitted
lacb end of each cylinder, and both high-pressure and low-pressure ralTcs
to be free to lift from their seats to reliere the cylinder of water,
be low-pressure cylinder most be fitted with a fiat, balanced slide valTe ;
iston TalTc on tbe low-pressure cylinder will not be accepted,
be pistons to be of cast iron or steel, strongly ribbed, light and rigid,
fitted with self-adjusting rings, each piston to baTe two or more rings.
El to oTcrride counterbore of cylinders, to prerent wear to a shoulder,
ton rods to be of forged steel securely fastened to pistons and cross-
ds. Crossbeads to be of steel with adjustable shoes. Connecting rods
»e of steel witb remorable babbitt-lined boxes for crank pins and bronse
es for crossbead pins.
lie crank shaft to be forged in one piece ; counterweights for balaneing
proeating parts to be forged witb it or securely fastened thereto. V alye
I, eeoentno rods, and rocker shafts, as well as all finished bolts, nuts,
, to be of best forged steel.
igging shall be fitted as extensirely as practicable to cylinders, receir-
and steam chests. This shall be done after a preliminary run of the
ne In order that any defects in castings or Joints may be readilv found,
arrangement for securing the lagging in place shall admit of its ready
oral, repair, or replacement.
le steam and exhaust outlets shall be so placed as to admit of piping
I eltber side witb equal facility. Blank flanges shall be furnished con^
B wben required to corer altemative outlets.
urottle and exhaust Talres to be OO^egree-angle Talye, looking up, nn-
otherwlae specified. Handwbeels to be marked, indicating direction of
Ing for opening and dosing. Wben so directed, larger sixes shall be
laned witn by-pass tsItcs for warming up cylinders.
le goremor to be of tbe weight and spring type, arranged to operate tbe
i
-preesure Talre by a shifting eccentne, thus automatically rarying the
e travel and point of eut-oixr Ko dashpots or friction washers shall be
In ite construction.
m speed rarlatlon must not exceed 9^ per cent wben load Is Tarled
'een full load and 90 per cent of full load, gradually or in one step, engine
iji£ witb normal steam pressure and yacunm. A yariation of not more
Sfper eent will be allowed when full load is suddenly thrown on or off
generator, witb constant steam pressure either normal, or 20 per cent
a normal; a yariation of not more than S| per cent will be allowed
1 90 per oent of full load is suddealy thrown on or off tbe generator, witb
)
1166 BLECTEICITY IN THE UNITED STATES KAVY.
constant Bteam pressare 20 per oent below normalt eilhaast fn both
be either bito condenser or atmosphere. No adjustment of the g
or throttle valve daring the test snail be necessary to inavre proper ;
formance under any of the above conditions.
The engine column to be designed to enclose all moving pstfta as fsri
practicable, or where weight may be saved, by using a wrouslit-eteel fiase
with an enveloping enclosure of metal. Detachable hinged doors to be pr»-
vided for examining moving parts while in operation. The design to ^ba-
inate ail chance of oil or water leaking or being forced through.
Stuffing boxes for piston rods to be slightly longer than length of stroks,
in order that no part of the rod exposed to the oil in the enclosure vUl (
the cylinder. Stuffing boxes for piston rods and valve rods to be
from the outside of the enclosing case of the enflrine.
A guard plate to be provided to prevent oil from being thrown
the lower cylinder heads and valve chests.
Engines are required to operate satisfactorily without the use of labn-
eants in the steam spaces. The lubrication for all other working sarfara
shall be of the most complete character. No part shall depend on squiit-
can lubrication.
Forced lubrication shall be used wherever practicable, which includsi
engine shaft, crank pins, erosshead bearings, eccentric, etc. Theengtee
shall be capable of satisfactory operation with a low grade of lubrieaciw
oil, and the forced lubrication snail not be a necessarvmctor in its oool aaa
satisfactory running. The intent of the forced lubrication is to redi^e
friction, noise, and attention requir^.
The pressure for such forced lubrication shall be approximately 15 ponadi
per square inch, and shall be bet\feen 10 and 20 pounds under all serries
conditions.
The bedplate is to contain a reservoir and cooling chamber of ample es-
paeity, to be provided with a strainer which may be removed withoat inter-
rupting the oil supply. The pump to be direct driven by a crank or ecceutrie
on the engine shaft, construction to be simple and durable, and to fnclwi*
a proper guide or support for the plunger rod. The pump to handle elea
oil oiuy, not drawing from the top or bottom of re8ervolr.
To allow inspection while running, the engine crank is not to dip In oQ is
reservoir.
Flv wheel to be turned on face and sides. Inner edge to be flanged to
retain any oil Which may drip thereon. Hub to be split and chunped to
shaft bv through bolts. A steel starting bar or its equivalent to be fur-
nished in sizes of 16 K. W. and over, the fly-wheel surface to have not lesi
than six holes for starting bar.
Mandrels, with collars, complete, shall be furnished for renewing whtte
metal of all bearings so fitted.
«£]!fBRATOIft«
To be of the direct-current, multipolar type, eompound-wotind loof-
shunt connection, designed to run at constant speed and to furnish s
Eressure of 126 volts at the terminals, at rated speed with load varyixif
etween no load and one and one-third times rated load.
The raaguet yoke or frame to be oircular in form, to have Inwardly pro-
jectlng pole pieces, and to be divided in half horizontally, in all generaton
above 5 K. W. capacity, the two halves being secured with bolts, to allov
the upper half with its pole pieces and coils to be lifted to provide for in-
spection or removal of armature. Pole pieces to be bolted to frame, bolti
to be accessible in assembled machine to enable removal of field coils vidi-
out disturbing armature or frame. Magnet frame to be provided with ttro
feet of ample size to insure a firm footing on the foundation.
Facilities for vertictd adjustment of frame to be provided In sixes of
16 K. W. and above.
Armature spider to be designed to avoid shrinkage strains. To b«
accurately fitted and keyed to shaft and to have ample bearing etafuoi
thereon.
The disks or laminations to be accuriUely punched from the best quality
thoronghly annealed electrical sheet steel, slots to be punched in peni^ieiy
OKNERATOB. 1157
of UuniBAtilons to reoeive armature vindings. Bialu to be masnetieally
faifliilated from one another, and securely keyed to spider or hela in some
other suitable manner to obviate all liability of displacement due to maa-
netie drsg, etc. Space blocks to be inserted between laminations at oertam
interrslf to proTlde TentUatinf ducts lor cooling the core and windings.
Laminatioos to be set up under pressure and held securely by end flanges.
Bolts holding these end flanges most not pass through laminations.
The commutator bars or segments to be supported on a shell, which must
>e either part of or directly attaohed to the spider, to prevent any relative
motion between the windingB and these segments. Ban to be of hard
drawn copper finished accurately to gauge. Insulation between bars to be
of carefully selected mica and not less than 0.08 inch thick, and of uni-
form thickness throughout.
Bars to line with shaft and run true, to be securely clamped by means of
bolts and clamping rings. Bolts to be accessible for tightening and remov-
able for repair.
Brushes to be of carbon. In sizes over 6 K. W. there shall be not less
than two brushes per stud, each brush to be separately removable and
adjustable without interfering with any of the others. The point of con-
tact on the commutator shall not shift by the wearing away of the brush.
Brush holders to be staggered in order to even the wear over entire
inrface of commutator ; the generator to be provided with some device tor
ihifting all the holders slmultaHeouslv. All insulating washers and
brushes to be damp proof and unalfected by temperature up to 100^ C.
finished armature to be true and balanced both electrically and mechan-
ically, that it may run smoothly and without vibration. The shaft to be
sroviaed with suitable means to prevent oil from bearings working along
lo armature.
All copper wire to have a conductivity of not less than 98 per cent.
The snunt and series field colls to be separately wound and separately
nonnted on the pole pieces. The shunt and series coils, respectively, of
jiy one set to oe identical in construction and dimensions and to be
eadily removable from the pole pieces. The shunt coils as well as the
erles coils are to be connected in series.
In sizes of 15 K. W. and above a headboard is to be mounted on the
enerator containing the necessary terminals for main switchboard and
qualizer connections, shunt and series field connections, pilot lamp, and, If
pacified, an approved tvpe of double-pole circuit breaker whose range of
djustment ahali cover from 100 to 140 per cent of rated full-load curreu^t of
he generator. Field current not to be broken by -the circuit breaker.
The field rheostat to be of fireproof construction suitable for mounting
Q baok of switchboard, with handle or wheel projecting through to front,
Ither directly connected or by sprocket chain, handle to oe marked indicat-
ig direction of rotation for raising and for lowering voltage of generator.
lie total range of adjustment to be from 10 per cent above to 20 per cent
elow rated voltage, the variation to be not more than one-half volt per
«p at both full load and half load.
The eomponnding to be such that with engine working within specified
mite, flelct rheostat and brushes in a fixed position, and starting with
>niiAl roltage at no load or at full load, if the current be varied step by
ep for no load to full loader from full load to no load, and back again, the
ination from normal voltage shall at no point be in excess of 2 per cent.
The dielectric strength or resistance to rupture shall be determined by a
ntinned application of an alternating E.M.F. for one minute.
I*he testing voltage for sets under 16 K. W. shall be 1,000 volts and for
ta of 16 K. W. and above shall be 1,600 volts, and the source of the alter-
■ting E.M.F. shall be a transformer of at least 5 K. W. capacity for sets
60 K. W. and under, and of at least 10 K. W. capacity for sets of greater
aut than 60 K. W.
e teat for dielectric strength shall be made with the completely as-
nblod apparatus and not with its individual pafts* and the voltage shall
applied between the electric circuits and surrounding conducting
kterial.
The teats shall be made with a sine wave of E.M.F. , or where this is not
iilable, at a voltage giving the same striking distance between needle
nts in air, as a sine wave or the specified E.M.F. As needles, new sew-
needles ^lall be uaed. During the test the apparatus being tested shall
iibi^ lUUM^TUClTT IK THB UNITBD 8TAT1S8 KAYT.
b# AikttiM«il ¥y ft MMTk gmp of needle points set for » Toltage ex<
i4>auii^ n^Hftge by 10 per cent.
wiUk iKiiektee In a fixed position there sh*U be no sparklnc when loedii
%c«UH«Jly ineieMed or decreased between no load and full load ; no dstii-
i&4M««al »^arking when load is raried up to one and one-Uiird times rated ~
«K^ ikwhinf when one and one-third ImuI Is remored or applied In one _
(1M j[Hinp In Toltage must not exceed 16 per eent when full load Is
^Hait^r thrown on and off.
'the temperature rise of the set after runnlnc continiioasly uiMler fSS
Med load for four hours must not exceed the following :
Armature . .
Ck>mmutator
Field coils
Shunt rheostat
Series shunt .
Method of meMure-
ment.
Electrical .
Thermometer
Electrical .
Electrical .
Thermometer
allowmble
lii«C
331
€0
78
The rise of temperature to be referred to a standard room temperature el
36^ C, and normal conditions of rentilation. Boom temperature to be
measured by a thermometer placed 8 feet from commutator end of the
erator with its bulb in line with the center of the shaft.
The generator to be capable of satisfactory operation for a period of
hours carrying one and one-third times its rated full load, and no part shall
heat to such a degree as to injure the insulation.
Generators of the same sixe and manufacture to be ci^iable of cmenUiea
In parallel, the dlrision of the load to be within 20 per cent throughout ttie
range. The magnetic leakage at full load shall be imperceptible at a hor>
Uontal distance of 16 feet, measurements to be taken with a horisontal
force instrument.
The minimum allowable efficiencies of the generators are as follows :
Loads.
K.W.
t»
1
1
*
Percent,
Percent,
Percetit.
PercemL
2A
78
78
76
73
6
80
80
78
75
8
84
84
83
80
16
87
87
86
84
94
88
88
87
85
82
88
88
87
86
60
89
89
88
86
. 100
90
90
89
87
SPECIFIOATIONS FOB TUBBO-GENEIUTIKa SBTS. 1159
Typical RMvlts of TMte •■ CI«B«rAtlBr i^ts
Blse.
100
K.W.
60
K.W.
32
K.W.
24
K.W.
Neater oonsamption per K.W. hoar ;
iformal steam and vaoaiun lbs.
29.8
31.6
29.7
28.2
36.0
36.6
86.6
88.4
34.0
84.1
Smrine regulation %
foil load to no load
!f ormal steam and Taenom
2.77
• • •
1.36
2.8
2.66
1.9
2.9
2.
2A
1.0
Snfflne regulation %
Pun load to no load
K)% abore normal steam with
raeuum
• • •
s • •
• • •
• • •
2.66
• • •
1.2
1.96
1.75
2.4
3.0
2.66
Snffine regulation %
P'uU load to no load
90% below normal steam with
raeuum
*2.«
...
2.24
3.17
8.27
2Ji
2.09
2.67
8.0
3.6
6.0
]^enerator efflolency %
Pull load
91.3
91.7
89 J>
89.1
88.8
88.8
89.1
88.8
88.2
88.6
88.7
Femperature rise in
Armature coils
By resistance, <H?
32US
33.3
...
22.
18.
24.8
20.8
19.
22.
26.1
20.1
23.2
temperature rise in
nela coils, shunt
3y reslsUnce, <>G
29.
81.
• • •
24.
24.
30.7
18.1
26.7
20.8
19.2
213
19.0
femperature rise
>>mmutator
3y thermometer, <K)
28.
• • •
24.6
23.
19.
18.
14.6
16.
17.
29.
21.
•PBGUnCATlOirA FOR TVlftllO-AKinBliATKirCl
IIBTS.
Elach set to consist of an electric generator driven by a steam turbine,
th mounted on a common bedplate.
The set as a whole shall be as compact and light as is consistent with due
^rd to strength, durability, ana ejfidenoy. The maTrimnm allowable
rmal speed, weight, and over-all dimensions are:
isein
LW.
R.PJtf.
Weight
in lbs.
Length
in inches.
llax. width
over pipe
connections.
Width in
inches
base.
Height
in
inches.
200
300
1700
1600
25.000
20,000
150
165
inches.
100
100
75
76
87
90
rhe design shall provide for accessibility to all parts requiring inspee-
n during operation, or adjustment when under repair. Sets are to be
ngned to operate counter-clockwise when facing the steam inlet. The
rign to be preferably such that the same parts may be used in each, in
ler to avoid increase in number.
1160 EliECTKIGITY IN THE UNITED STATES NATY.
The sets mtuit be capable of mnnins without undue noiae,
wear, or heating. Must be balanoed and run true at aU loada, np to 33}
per oent above ratine; must be eapable o£ jninning for ions periods nodm
full load.
Cast or wrou|^t-iron shall not be used for bearing surfaces. Both upptr
and lower halves of main bearings to be removable without removal or 0^
placement of shaft.
Suitable thrust bearings will be provided to prevent movenient of tibt
shaft in direction of its length as might be caused by rolling of the ahiph
Sets to be erected with shaft extending in a fore and aft direction.
The combination bedplate to be a substantial easting^ and provided with
accurately spaced drilled holes for securing to foundation. ProvisioB wiB
be made to receive duct from the ship's ventilating system.
Seats for all boltheads and nuts to be faced. Alinuts to be case haideoed
and to be United States standard sixes. Where liable to work loose from
vibration, nuts are to be secured by use of jam nuts and spring ootten.
All bolt ends to be neatly finished.
Adjoining portions of the machinery shall be given corresponding macks
whenever this may be desirable for insuring correct assembling.
Wrenches and lifting eyes to be furnished in sets as specified.
Omvas covers to be furnished for each set, engine covers and senerator
covers to be sepanite. To be made of Navy standard 8-ounee khflud oottoo
ravens (Specification 215) stitched together with a double seam.
If reqmred in advance of delivery of set, templates of the oomblnation
bedplate or of the shunt field rheostat shall be furnished by the oontractor
free of additional expense. These may be of paper, full sise, with dimen-
sions entered complete in order to obviate errors due to shrinkage or expan-
sion.
Interchangeability among the different sets and their spare parts of the
same sise and make as furnished in any one contract is requirod. This to
be demonstrated as part of the final test for acceptance.
Spare parts supplied to be boxed and protected in aooordanoe with
*' Specification 3B2'* issued by the Navy Department, September 12. 1906.
The general appearance of the set resulting from design and workman-
ship must be of the highest character. Any defect not cauaed by *iwwm
or neglect, which may develop within the first six months of service, to be
made good by^ and at the expense of the contractor.
The works in which the construction of the contract is being carried on
shall be open at all times during working hours to the inspection officer and
his assistants. Every facility shall be given such inspectors for the pcoper
execution of their work.
Copies of the original shop drawings of the genenting set 9haU be fur-
nisheS as part of the ooutraet as soon as possibid after safd ebntmet is
awarded. Before final acceptance of generating set a complete aet of fiiat-
class detail and assembly drawings on tracing cloth shall be supplied.
Turbine.
The turbine will be of the horizontal multi-etacce tyije* It will be de-
signed to run condensing with maximum practical emciency at all loads.
It will be of sufficient power to drive the generator for an extended time at
the rated speed when said generator is carrying li load.
The normal steam pressure under which the turbine will operate^ and at
this steam pressure the maximum steam oonsumption for various degrees
of vacuum, is:
Steam K.W. pressure,
normal.
Water consumption per K.W. hour, full k>ad.
25 in. vac.
26 in. vac.
27 in. vac.
28 in. vac.
200
300
150
200
• a •
30|
28}
281
261
27
251
SPECIFICATIONS FOB TUBBO-GBKEBATING SETS. 1161
These rates should be interpreted as dry saturated steam, steam pres-
sure being measured at throttle and vacuum in exhaust casing. Super*
heating shall not be used in the test.
The turbine to run smoothly and furnish the required power for full
load at any steam pressure within 20 per cent (above or below) of those
given in the table, and exhausUnK to oondenser at 25 inches of vacuum;
to furnish power for 00 per cent of full load at steam pressure 20 per cent
below normal, and for full load at any steam pressure between norioal and
20 per cent above normal, when exhausting into the atmosphere. It will
bear without injury the sudden throwing on or off of one and one-third
times the rated load of the generator by mitking and breakinc the gener-
ator's external drcuit.
The steam outlets shall be so plaoed as to admit of piping from either
side with equal facility. Blank flanges shall be furnished complete when
required to cover alternative outlets, turbine to have exhaust outlet on
right or left side as specified. AU piping shall be firmly supported at
points close to the turbine, so that the weiff&t of same shall not effect the
alignment of the parts involved.
Steam inlet valve shall be a combination throttle and emergency valve
equipped with strainer intervenins between valve and steam line. It will
be connected to the emeraenev governor in such a way that it will auto-
matically dose if the speed of the turbine rises more than 15 per cent above
normugJ. Flange drilling to conform with specifieatione of the Bureau of
Steam Engineering.
The ^vemor wul be of the centrifugal type ooerating a series of valves.
I Jigging to be fitted as extensively as practicable to turblae. It shall be
ione after a preliminary run of the turbine in order that any defects in
auting or joints may be readily found. The arrangement for securing the
aaring in place shall admit of its ready removal, repair, and replacement.
Tne speed variation will not exceed 2i per cent when load is varied
>etween full load to 20 per cent of full load gradually or in one step, turbine
mining with normal steam pressure and vacuum. A variation at not
acre than 3) per cent will be aUowed when full load is suddenly thrown
»n or off the generator with steam pressure constant between normal and
O per cent above normal, a variation of not more than 3i per cent when
0 per cent of full load is suddenly thrown on or off the generator with
onstant steam pressure at 20 per cent below normal, exhausting in both
sees either into condenser or the atmosphere. No adjustment of the
ovemor or throttle valve during the tests shall be necessary to insure
roper performance under the above conditions.
"The turbines will operate without the use of lubricants in the steam
saoes. Forced lubrication will be used on all bearings. The bedplate will
sntain an oil reservoir from which oil will be drawn oy a pump operating
irectly from the main shaft, and forced through the system. To be pro-
ided with a strainer which may be removed without interrupting the oil
ipply. The oil will be cooled by water which will pass through a coil
"ound which the oil will circulate.
Mandrels, with eollara, complete, will be furnished for renewing the
bite metal of all bearings so fitted.
The material and design of the turbine will be such as to safely withstand
1 straina induced by operation at the maximum steam pressure specified.
To be at the direct current, multi-polar tsrpe, compound-wound long-
lint eonneotion, designed to run at constant speed and to furnish a pres-
re of 125 volts at the terminals, at rated speed with load varying be-
een no load and one and one-third times rated load.
The magnet frame will be circular in form; will have inwardly pro-
ittng pole pieces and will be divided in half liorisontally, the two halves
ng seciired with bolts to allow the upper half with its pole pieces and
la to be lifted to provide for inspection or removal of armature. The
le pieces will be bolted to the frame.
The maipet frame will be provided with two feet of ample sise to insure
irm footing on the foundation.
«*flusilities for vertical adjustment of the frame will be provided.
I
1162 BLECTBICITY IN THE UNITED STATES KAV7.
The laminationB for the armature will be aoeurately pundied fron the
beet quality, thoroughly annealed, electrical sheet steel, siote to be punched
in the periphery oflaminations to receive armature winding . Tne Ibbm-
nations will be insulated from each other and will be aaaembled on the
spider or shaft and securely keyed. Siiaoe blocks will be inaoftecl betwmu
laminations at certain intervals to provide ventilating ducts for f>ffoKTFg the
oore and windings.
Laminations will be set up under pressure and held securdy by end
flanges.
The commutator bars wUl be supported on the shdl iHixoh will be korsd
directly on the shaft so that no relative motion can take plaoe between the
windings and bars. The bars will be of hard drawn copper finished aeea-
rately to gauge. The insulation between ban will be of oaref iilly nrlfirtnt
mica not lees than .03 inch thick. The bars will line with tbe shaft
and run true and will be securely held in place by means of **'*«Trrr*g
ringB.
The brushes will be of carbon. Each brush will be separately removable
and adjustable without interfering with any of ^e others. The point nf
contact on the commutator will not shift by the wearing away of the bnuk.
Brush holders to be staggered in order to even the wear over entire Bnr>
face of commutator; the generator to be i^vided with some devices for
drifting all the holden simultaneously. All insulating washers and bus
to be damp proof and unaffected by temperature up to 100 degrees C
Finiihed armature to be true ana balanced both electrically and m«i
ioally, that it may run smoothly and without vibration. The afanft to be
provided with suitable means to prevent oil from bearingi workinc
to armature.
All copper wire to have a conductivity of not less than 98 per eesit.
For sets of 100 K.W. and less the shunt and series field cofls to be __^_
rately wound and separately mounted on the pole pieces. Hie ahunt ttd
series coils, respectively, of any one set to be identical in oonstnietaon and
dimensions and to be readilv removable from the ^le |neees. Tbe diaat
eoils as well as the series coils are to be connected m senes.
A headboard wiU be mounted on the generator containing tbe neoessary
terminals for main switchboard, equalising connections, shunt end seriei
fidd connections, and pilot lamp.
The field rheostat to be of fire-proof construction suitable for mounting
on back of switchboard, to be provided with handle or wheel projeetuig
through to front, either directly connected or by sprocket chain, bandle'lo
be marked indicating direction of rotation for rusing and for lowering volt-
age of generator. The total range of adjustment to be from 10 per cent
above to 20 per cMit below rated voltage, the variation to be not more than
one-half volt per step at both full load and half load.
OpenttioB of Qememtorw
The compounding to be such that with turbine working within apeeified
limits, fiela rheostats and brushes in a fixed position, and starting with
normal voltage at no load or at full load, if the current be varied 8tq> by
step from no load to full load or from full load to no load^ and back agsiii|
the difference between maximum observed voltage and minimum obeerved
\ voUage shall not exceed 2| volts.
The compounding and heat run (full load and ovwload) of the generatuig
sets must be made with identical brush positions.
The dielectric strength for resistance to rapture shall be determined by
a continued application of alternating E.M.F. of 1500 volts for one minute.
Test for dielectric strength shaU be made with the completely aesemUed
apparatus and not with the individual parts, and the voltage shall be appBed
between the electric circuits and surrounding conducting material.
With brushes in a fixed position there shall be no sparking when load h
gradually increased or decreased between no load and full load; no detri-
mental sparking when load is varied up to one and one>third times ratnl
load, no flashing when one and one-thira load is removed or applied in
stajM.
The jump in voltage must not exceed 16 per cent when full load is
denly thrown on and off.
SPECIFICATIONS FOR TUBBO-OEKEBATING SBTB. 1163
The temperature riae of thle aet, after runmng oontinuouely under full
rated load with air of auxiliary ventilation at room temperature for four
hours must not exceed the following:
I/esreea C«
Annature. by thermometer 40
Commutator, by thermometer 46
Series field coils, thermometer 40
Shunt field ooils, reaiatanoe method 40
^unt rheoatat, reaiatanee method 76
Sttiea ahunt, thermometer 40
The rise in temperature to be referred to atandard room temperature of
26 deneea C. Room temperature to be meaaured b^ a thermometer placed
three feet from commutator end of the cenerator with ita bulb in line with
the center of abaft.
A avstem of air dueta for the ventilation of armature and commutator
ahall be provided. Thia ayatem afaall be connected to the ahip'a venti-
lating system. The amount of air per minute required for the vaxioue
aiaedaeta will not exceed the fcdlowiag:
Sim K.W. Cubic feet air per minute.
aOO 2000
300 3000
The generator to be oapable of aatiaf aetory operation for a period of two
hours carrying one and one-third times ita rated full load; alao full load
oontinuoualy In a room temperature of 80 degreea C, without auxiliary ven-
tilating ayatem, and no part ahall heat to auch a degree aa to injure the
insulation.
Generators of the same aiae and manufacture to be capable of operation
n parallel, the division of the load to be within 20 per cent throu^out the
■ange. The magnetic leakage at full load ahall be imi^eroeptible at a hori-
lontal diatanoe caf 16 feet, meaaurementa to be taken with a noriiontal force
natrument.
The dynamo room ia aupplied by a apeoial ateam pipe which uaually ia ao
onneeted that it can take ateam direct from any boiler or from the auxil-
uy ateam pipe, it paaaea into a ateam separator from which branches lead
o each of the generating'^eta in the dynamo room. Thia separator ia
rained by a ateam trap which aends the water back to the hot well in the
lain engine room.
The exhauat pipe from eadi aet joins a common exhauat which eonneota
rith the auxiliary exhauat aervice of tiie ahip. If the acta are located
elow the level of the ahip'a auxiliary exhauat pipe, a aeparator is placed in
le oommon exhauat pipe before it goes up ana joina we ahip'a auxiliaipr
Kbauat. Thia aeparator ia drained by a amall ateam pump, which la
iitomatloallv atarted and stopped by means of a float in the body of the
)parator, wnich float atarta tne pump when the aeparator ia full and atope
when empty.
In tho iateat veasels a separate oondenaer ia inatalled in the dynamo room
»r thm generating sets.
%]
Switehboarda are divided into:
Generator boarda.
Diatribution boarda.
The cenerator boarda are provided with two aeta of bua-ban. one aet for
e Uchting system, and the other aet for the power ayatem. The deaign is
eh that any of the generators can be operated singly or in parallel on
hmr system. Fig. 1 ahowa diagrammatioally the generator botud uaed on
B U. S. S. " Vermont."
Current is aupplied to the different appHanoea by means of diatribution
itehboards, which have two aeta of bus4»fB. one for lighting and one for
wer, and are oonneeted directly to the corresponding bua-bara on the
kin oenerator board. Feeders run direct from these distribution boards.
1164 ELBCTRICITT IK THE UNITED STATES HAVT,
•Mfa ftd*T Mof provided oitb • fiued toHch. IHatribntian bosnb u*
tinuoiB'5ith™eminbMrii* • ip " ihbb am-
Ward-L«iianl syatem of ooncrol. ■ upknia ■anantor vs* usad for aA
tutnt. Thiaraquiied KOftdditiouilHt of biB-Cu OD Uu
Fia. 1. DlBgnifi of VtrraoDi (jonentor Bwitohboiud.
kch titnvt. Fig. 2 nhowB tbt dnign i
eriu Said >bon ci
\oi
„ ._ „ to fie noted Unit (he ti__.
SnenlniT on llie puwer and LiRhtinE lysletus have the rtaht-faand blkdei tl
ai triple pole field amtchea cloeecC givina KlT-eioitalioo tlm>uch the 6«ld
rbfoalal, w£ile the niBcliinB far turret tamlnK hu the. middle bladca cfcBHl,
field naiatuiaa ettaishad tu the controller in tfaa turret.
I
' 1.
!M
a
1166 ELSCTBICITZ IN THB UNITED STATES MATT.
Pla. 3. IH*siwno( Doubls Dyouno Room DiitribntioB.
ddent dinbling one plant will not kffKC tha B^Oat Bbility (< tha A^
loh pluit ia of BUffielBat topudtr to carry ths mtin woridnk loBd.
Hie distribution iiahowndlagrammatieallv In Fig. 3.
« room ara contcoUsd by tha saina boaid. TIm feadtn to Iba
WIRIKG. 1167
parts of the ship are supplied by the two dlstrlhutioii boards, one forward and
»ne aft. Each of these dUtriDution boards can take energr from either of
the generator boarda by means of transfer switches and tnteroonneotlng
Feeders.
The oirooits supplying the lights in the engine and Are rooms, and the
turret feeders are made double, one set running from each distribution
iKMud, and transfer switches provided at their ends; thus allowing these
important parts to be suppllea even if either dynamo room or either dia-
trioution board is destroyed.
Hie prineipal requirements of the Nary standard speeifioationi for light
ind power conductors are :
All conductors to be of soft-annealed pure copper wire, and, unless other-
trise qMcified, each wire to be thoroughly and evenly tinned.
All sinsle strands must show a conductivity of not less than OB per cent
ind the finished cable not less than 95 per cent of that of pure copper of
h» same number of droular mils.
AH layav of pure Puna rubber must contain at least 08 per cent pure
Para rubber; must be concentric, of uniform thickness, elastic, tough, and
'ree from flaws atoA holes.
All layers of vulcaniaed-nibber compound shall consist of the best grade
>f fine unracovered Para rubber, mixed with sulphur and dry inorganie
nineral matter only. The compound shall contain from 99 to 44 per cent,
jy weight, of fine Para rubber, and not more thvi 3 per cent, by weight,
n sulphur. Thb sulphur shall be so combined with the Para rubber tnat
lot more than two-tenths of 1 per cent shall remain in the compound as
ree sulphur. The rubber shall be so conqK>unded and vulcanised, that
rhflo test pieces taken from the wire (2 inches between jaws and 4 inch
vide when possible) are subjected to a tensile stress, the^ shall show a
>reaking strain of not leas than 1,000 pounds per square mch, and shall
tretoh to at least three and one-half times tneir original length, llie
aws will be separated at the rate of 3 inches per minute.
When test pieces, as described above, are subjected to a stress of 900
lounds per square inch for ten minutes, the compound shall be of such a
tharaoter as to return to within 50 per cent in excess of its original length
t the end of ten minutes after being released.
All lasers of vulcanised rubber must be concentric, continuous, and free
rom flaws or holes: must have a smooth surface ana circular section; and
aust be made to a diameter in the finished conductor as tabulated.
Measured dimensions "over vulcanised rubber" or *'over tape" must
ome within 2| per cent of tabulated values, the departure in no case to
xoeed ^ inch.
All layers of cotton tane must be thoroughly filled with a rubber-insulating
on4>ound, the tape to oe of a width best adM>ted to the diameter of thai
art of the ooaductor which it is intended to bind. The tape must lap
bout one-half its width; must be of such thickness as to maJce dimensioha
onform to tabulated values, and be so worked on as to insure a smooth
orfaoe and circular section of that part of the finished conductor which is
eneath it. The tape must not adhere to the rubber.
All exterior braia or braids must be closely woven, and all, except silk
raid, must be thoroughly saturated with a black msulating waterproof
impound which shall be neither injuriously affected by nor have injurious
BTect on the braid at a temperature of 06° C. (dry heat), or at any stage of
i« baking test, nor render the conductor less pliable. Wherever a di-
meter over outside braid is tabulated or specified, the outside surface must
a sufficiently smooth to secure a neat working fit in a standard rubber
Msket of that diameter for the purpose of making water-tight joints.
Measured dimensions **over braid " must* come withm 5 per cent of
kbulat«d values, the departure in no case to exceed A inch.
All wire and cable shall be subjected to a test for continuity and for insu-
tins properties, the latter by measurement of insulation resistance and by
tfh potential test on the entire length of the oables, either or both, as per
le following table:
1168 ELECTRICITY IN THE UNITED STATES NAVY.
LiohHng vnrt.
Up to and including:
500,000 o.m., single . . .
650,000 cm., single . . .
800.000 cm., sinfsle . . .
1,000,000 cm., single . . .
Ail twin wire:
Between conductors . . .
From conductors to ground
Double condudar.
Plain:
Between conductors . . .
Each conductor to ground
Diving:
Between conductors . . .
Each conductor to ground
Silk . . .
Bell wire
Bell cord
CcUU.
Interior-communication cable:
Between conductors . . .
Each conductor to ground
Night ^signal cable;
Conductor for
Completed cable:
B^ween conductors . . .
Cable to ground .....
Insulation resistanca.
30
ut
IjOOO megohms per knot
900 megohms per knot
800 megohms per knot
750 megohms per knot
1,000 megohms per knot
1,000 megohms per knot
1.000 megohms per 1,000 feet
1,000 megohms per 1,000 feet
1,000 megohms per 1.000 feet
1,000 megohms per 1,000 feet
No test
500 megohms per 1,000 feet
No test
1,000 megohms per 1.000 feet
1,000 megohms per 1,000 feet
1,000 megohms per 1,000 feet
1,000 megohms per 1,000 feet
50 megohms per length . . ,
4.500
4.500
4.500
4,500
3,500
3*500
2;500
3*500
3.500
3.5O0
5.O00
1.500
&000
1.500
3.500
3.500
3,500
3,500
Tests for insulation resistance shall be made after immersion of wire
(not less than three days after manufacture, the three days to be reckoned
back from the end of the immersion period) in fresh water at a tempera*
ture of 2^ C. for a period of twenty-four hours, the test to be made by the
direct-deflectbn method at a potential of 500 volU after five minutes
electrification. ..... ....
High-potential tests shall then be made with the wire still unmersed, the
source of power supply to be a transformer of not less than 5 K.W. capactty*
For double-conductor silk and bell cord the high-potential tests will be made
with the dry wire freely suspended in the air.
Six-inch samples of wire, with carefully paraffined ends, shall be sub-
merged in fresh water of a temperature of 22° C. for a period of twent3s
four hours. The weight of the wire before and after submersion, deduct-
ing weight of copper and vulcanized rubber, will sive the per cent of water
absorbed by the braids. This snail not be more than 10 per cent.
A sample of suitable length (1 foot k>ng for small wires) shall be exposed
for several hours at a time, alternately, to a temperature of 05^ C (diy
heat) and the temperature of the atmosphere, over a period of three daya
The braid and insulation must then stand sharp bending to a radius of seveo
times the diameter without breaking or cracking. For twin conductor the
pijnjnft^Tnn diameter will be used.
Unless otherwise called for, all wire supplies to be delivered in lengths of
not lees than 500 feet. To be delivered on reels of strong construction to
admit of transportation to long distance, which reels on direct purchases
will remain the property of the Government. The flanges of the reels to bt
WIRING.
1169
least 8 inohee longer in diaoMter than the diameter throush tlie eoiL
) loose end of the ooil to be secured to prevent damage in timnsit.
JO insure mf^ximnm flexibility, the pitch of the *' standing " or
" of all conductors eo formed shall not exceed values tabulated:
(«
Number of wires
Length of pitch,
expressed in
forming strand.
diameters of indi-
vidual wires.
*
7
30
19
60
87
90
61
120
91
150
127
180
Hben greater conducting area than that of 14 B. A S. G. is required, the
luotor shall be stranded in a series of 7, 19, 37, 61. 91, 127, wires, or as
' be specified, the strand consisting of one central wire, the remainder
around it concentrically, each layer to be twisted in the opposite direc-
from the preceding; and all single wires forming the struKi must be
be diameter given in the American wire-gauge table as adopted by the
irican Institute of Electrical Engineers, October, 1893.
Slaffle G*sd«ctor«
Tablb of Standard DiMXNSioNa:
Actual
G. M.
Number of wires
in strand.
■is
Diameter, inches.
Diameter in 32ds
of an inch.
;>roxi-
»C.M.
Over
copper.
Over
Para
rubber.
Over
vul-
can-
ised
rub-
ber.
Over
tape.
Over
braid.
4,000
0,000
1,000
5,000
8.000
O.OOO
0.000
0.000
0.000
0.000
5.000
0.000
5.000
0.000
0.000
0.000
DbOOO
5.000
0,000
D.000
9,000
>.000
>.0U0
4.107
9,016
11,368
14.336
18.081
22.799
30.856
88,912
49,077
60.088
75,776
99,064
124,928
157.563
198,677
260.527
296.387
873.737
413.639
521.589
657,606
820.310
1,045,718
1
7
7
7
7
7
19
19
19
37
37
61
61
61
61
61
91
91
127
127
127
127
127
14
19
18
17
16
15
18
17
18
17
18
17
16
15
14
15
14
15
14
13
12
11
.06408
.10767
.12090
.13578
.15225
.17121
.20150
.22630
.25410
.28210
.31682
.36270
.51363
.67672
.62777
.70488
.74191
.83304
.93548
1.05053
1.17962
.0953
.1389
.1622
.1670
.1837
.2025
.2328
.2576
.2854
.3134
.3481
.3940
.4386,
.4885
.5449
.6080
.6590
.7361
.7732
.8643
.9667
1.0818
1.2109
7
10
10
10
11
12
12
13
14
15
16
18
19
20
22
24
26
20
30
34
38
42
46
9
12
12
12
13
14
14
15
16
17
18
20
21
22
24
26
28
31
32
36
40
44
48
11
14
14
14
15
16
16
17
18
19
20
22
23
24
26
28
30
33
34
38
42
46
50
1170 SLBCTBItiITT IN THE UKITED STATES NAVT.
rollod tjju On
Bacvnry. to mMt tbn nai
Ssoana. A lays of vu\<
Tbird. A layer of cotton tuB.
_ Foiuth. A cloH braid to b» nwda of No.
bnided with thr« «&di, for all coodiuton uiul_ ,^ -__ .„_
of No. la thne-ply cotton Ihnad, br^d«d with hat end*, for all BODdncI^
el and abon St.OOO circular mila Tlie outMe diamMv OTar th* tol
to b« in oonformity with that tabulatad.
TaMiB of SrAHDaBD DmBmnm:
All (win Uvhting conductors ihall eooijit ot two condoeton. aadi
which •hall te inaulatrd ai (ollowr
Fint. A layw of pure Para rubbar, tiot lea than A •>' *■> Id™ in
DCH, lolled on.
Beeond. A layer of vulcaniied nibbar.
Third. A loyar ot cotton lape.
Two lueh insulated eonduMors shall be laid tosether, the int«atiea
Blied with juts, and covered with two Imytn ot ckae braid.
Each braid to ba mads of No. 20 two^ly cotton thread, biaida
three ands.
Three methods of
ondnit; 3. Molding; and 3, Porcelain iiipTKiits.
oudult Is tbc prlnoJpal tnetbod. belruruseiimalmoat all spaeea Wk*
,.jitH!tlTa deok. and whereTer wiring aiposad to neohanleal IM«T
or the weather, [ron-armored conduit Is used, excapt within 11 (aei at tit
■tandard cc
Conduit pseelng through watar-tlght bulkheads )■ made water4l(fa( U
means of stuttng-boxee and heiuf^pscklnff. Water^tivhtrieas Is prorlM
at the ends ot eondait bf a stufflng-boi and • saft-mbber neket, thinfk
which the condoolor passe*. LongTinee of oondntt psialng ttrongh —tmiI
LZOHTIKCH8T8TSM. 1171
r--T-j,-T- ji '—^ r- — w — ^w V ^ pvoiMr
mUs, wlii«h dliido the nm Into water-tight Motions, thni preTeniuic
- ' " " - mthronffE
ar-tlfht oompArtmenti are pwfiM with ^Iwnd ooapUiiti
mUs, ■■ " " " " ' ' '" ^ "^ ----
eonanit Into another 'eompartment. Theee~fland oonplingi are aJio
in a flooded oompartment from allowing the water to run
1 where oondoit paaeee Tertieally through decks.
Wood molding is nsed in liTing spaees hut has been abandoned on
latest Tsseels. it consists of a backing piece fastened to the iron work
be ship, to which the molding proper is secured by screws and corered
I a woo<kui oapping-piece. where leads installed in molding pass
ugh water-tight bmkheads, a bulkhead stuffing-box is proTided for
ir-tightn
Porcelain supports are used in dynamo rooms and for the long feeders
ih are run in ^e wing passages where there is no danger of interference.
Ang-tnbes are used where the wires pass through bulkheads, the saoia
ith molding.
U conductors are branched by being run into standard Junetioii boxes,
ih are usually prorided with fuses. Where conduit is used these boxes
tapped, to hare the conduit screwed into them ; where molding or
elain is used the boxes are proTided with stuffing-tubes. The box corers
made water-tight with rubber gaskets ; inside the fuses and eonneetioii
« are mounted on porcelain bases.
le maximum drop allowed on any main is 8 per cent at the farthest
»• Mains are required to be of the same siae tnronghont, and to be of
circular mils per ampere of normal load.
Mt incandescent lamps are installed in air^ht glas* globes of different
es, depending upon position or location. Magasines are lighted by
gaslne Light Boxes," which are water-tight metal boxes set into the
Mines through one of its walls, and proTided with a water-K^^ht door
ing into the adjacent compartment, so that the interior of the box is
isiDle witiiout entering the magasine. The sides of the boxes have
windows, and each box is flttM with two incandescent lamps, each
• haying its own separate fused branch to the main, so that one lamp
M used as a spare.
witch Receptacles ** containing a snap switch and a plug socket are
Ided for attaching portable lamps.
a principal requirements of the standard Navy specifications are :
alt mt €3tta«le«lPower* — The unit of canole-ppwer shall be the
le as determined by the Bureau of Standards at Washington, D. C.
Ii«t«mietrlc Meaavre. — The basis of comparison of all lamps shall
le same spherical candle-power. The normal candle-power referied to
ese specifications shall be the mean horisontal candle-power of lamps
ig a mean spherical candle-power value of 82.5 pw oent of the mean
ontal candle-power, which is the standard value for filaments of the
anohored tsrpe.
r lamps having filaments giving a different ratio of mean spherical to
i horisontal candle-power, the norisontal candl^-power measurement
>• corrected by a reauction factor determined by uie Bureau d Stand-
or other authority mutually agreed upon.
Mt 4MuimtMgr« — The test quantity shall consist of 10 per cent or
of any lot or paekage, and in no case be less than ten lamps.
^
1172 BLECTBIGITY IN THE UNITED STATES KAV7.
From enoh package there will be seleotod at random the test QOBBiily te
the purpose of detemuDine the meohanioal and phyrical charaotcrieCm^f I
the uunps. the individual umits of oandle-power and watte -per l^wp^ «S|
finally the life and candle-power maintenance. Theee lunpe will be ki
as the test lamps.
AJi lamps ahall oonf orm to the manuf aoturen' standard ahapes axid
of bulbe, and to the standard forms of filament, and the standard
power and watts per lamp.
All bulbs shall oe uniform in siie and shape, dear, dean, and free
flaws and blemishes.
All lamps, unless otherwise specified, shall be fitted with the
Edison screw base, fitted with glaas buttons, fonningthe ineulatio
oontacts, and rendered impervious to moisture. The diella of
ahaU be of good quality brass, firmly and aocmmtdy fitted to tike bulb
moisturcHproof cement, and in length to conform to the National
Code of fire Underwriters.
The lamp filament must be symmetrieally disposed in the bulb a
not droop excessivdy during the life of the lamp when the lamp is burned a
test in the one horfsontal porition at a voltage correspondins to a '^-^
specific consumption <rf 3.70 watts per mean spherical candle and
excessive vibration.
All filaments must be unifonn and free from all imperfections, spotm,
disoolorations.
Leading in wires must be fused into the glass with the joints beti
per and platinum wires bedded wdl within the glass; the wires to be straiglrL
wdl separated, and securely soldered to the base and cap, without exoess at
solder and so threads of baser-are free from solder.
All lamps must have first-class vacuum, showing the oharactaistic gisv
of good vacuum when tested on an induonon coil.
A printed labd, showing manufacturer's name or trade-mark, ^oltagi^
and candle*power, must be placed on each lamp near base.
The lamps must be well made and free from all defects and impeifectiaak
so as to satisfactorily meet the conditions of the Uchting service.
If 10 per cent of the test quantity of lamps selected from any parlm^
show any physical defects incompatible with good worlonanship, good ser*
vice, or with any clause of these spedfioations, the entire lot from wlneh
these lamps were sdeoted may be rejected without further tests when tests
are made at the lamp factory. When the tests are made elsewhere, if lbs
firat test quantity prove unacceptable, 20 per cent more lamps will be
sdected from the package or lot of lamps, and should 10 per cent of *>»■■
second lot of sample lamps be found to h&ve any of the phArsical dcfcou
above mentioned, the entire lot from which these lunps were sheeted may be
Rjected without further test.
When tested at rated voltage the test lamps shall not exceed the lumti
l^ven in schedule. IS 10 per cent of test lamps from any package is found to
fall beyond the limits stated, when tests are made at the tannp factory the
entire lot from which these lamps were sdected mav be rejected withoet
further test. When tests are inade elsewhere, if the first test quanti^
prove unacceptable. 20 per cent more lamps will be selected from the package
or lot of lamps, and should 10 per cent of these additional Uunps be found
to fall beyond the limits the entire packai^ may be rejected without further
test.
Life tests shall be made as follows: From each acc^ted package of
lamps two sample lamps shall be selected which approximate most dosely
to the average of the teat quantity. One of the two lamps thus selected wffl
be subjected to a life test and designated as the life te»l lamp, the seocmd
or duplicate lamp bdng reserved to replace this teal lamp in case oi acd-
dentai breakage or damage during the life test. The test lampa sbafl be
operated for candle>power performance at constant potential, avi
variations of voltase not to exce^ one-fourth of 1 per cent either
The voltage for each lamp shall be that corresponding to an initial sp _
consumption of 3.76 watts per mean spherical candle, or if tested upon a diff-
erent !>asis, the resnlts shall be corrected to a basis of 3.76 watts per rnmn
spherical candle. If desired, the life tests may be made at such other watte
per candle as may be mutually agreed upon.
Readings for oandle-power and wattage shall be taken' dttrin)^ life at tlie
marked voltage of the lamps at approximatdy fifty hours, and at
LIGHTINQ-SYSTBM. 1173
f one hundred houn afterwards until the candle-power shall have faUen
ir cent below the initial candle-power, or until the lamp breaks, if within
period. The number of houxs the lamp bums until the candle-power
Menased to SO per cent of its initial Yalne, or until the lamp breaks, is
n as the useful or effective life.
e averaiee candle-power of lamps durins life shall not be less than 91
ent of their initial candle-power. In computing the results of test of
of lamps the average candle-power during life shall be taken as the
caetical mean of the values for the individual lamps of the lot tested,
mps selected for the life test, which for any reason do not start on
test, shall be replaced by others.
mps which are accidentally broken but are burned out on test shall not
unted to diminish the average performance.
case both test and duplicate lamps are broken or damaged before the
Bt is completed, the aveorage performance of all lamps <A the same class
ousiy determined under the same contract shall do assigned to the
ige represented.
all tests for determining average candle-power and life each
Ige -which will be affected by the results of test shall have at least one
on such test.
sorate recording voltmeter records will be obtained during the test
mps to show the average variation on the circuit,
len so tested the lamps shall averace at least the values for useful life
in the tables on pages 1176 to 1178,
Values for Oral Amtl^ovA PUOa tktmaMax&. MJigtuOmm
mps of this type of voltages 106 Mid below, at 110, 120, and above, and
it 220, may Dave double the limits of variation in the initial limits
led for their respective daases.
nps and other types of filaments to give equivalent performances.
: lamps between 1(20 and 125 volts, the useful life values shall be 95
nt of thoee given in the table, and for lamps between 126 and 130 volts
leful life values shall be 90 per cent of those given in the tift)le.
ralaen for lloaaA Balliw Vobalar, and otiicr Irregralar
I individual limits for irregular types of lamps, such as round bulb
ubular bunps, shall be twice the mdividual Imiits given in the body
I preceding schedules for regular lamps of corresponding candle-power.
; individual limits for metallised filament and roiind bulbs primo types
ips shall be 15 per cent above and 15 per cent below the mean candle-
' rating, and 15 per cent above and 15 per cent below the mean total
fating. Tlie candle-power rating referred to are the mean horisontal
»-power ratin^B of dear lamps without reflectors.
(c) IfaTjr Apocial Ijantpe.
lamps mnst conform in their general shape and form to drawing No.
C, see Figs. 4 and 4a, and overall dimensions must not be exceeded.
Sojectloas aad Peaaltloe.
I failuie of the-lamps in any package to conform to the spedfications
mechanical and physical characteristics, or to initial limits, may cause
lection of the entire package.
' failure df the lamps to give within 90 per cent of the values ol useful
ven in the tables may cause the cancellation of the contract.
tips which have not been used and are rejected under the terms of these
cations will be returned to the manufacturer at his expense, and no
ant will be made therefor.
mpt notice will be served upon the contractor of the test results on
that are rejected, or that fau to meet the specified requirements.
(
r
1174 ELBCTHICITY IN THB UNITED 8TATB8 NAYT.
/W.c/r DiVlNQ LAMP
Flo. 4. Standard Ineandesoent Lampa aa Covered by U. B.
Navy Speeifieationa.
LIOHTIMO-aXSTIM. 1175
<]
Fin. «i. BMadard Inciudgaonit Lunpa ■■ Corarad by U. 8.
1176 BLBCTRICITT IN THE UMITKD STATES NAVT.
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1178 BLBCTRIGITY IK THIS UNITKD flTAXES HAYZ.
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^4 V4»4
LIGHTINCh-SYSTEM. 1179
ring-lantertis oonalst of a glass oyllnd«r closed at eaoli end with a metal
haTliig the Joint between the class and metal paeked with a soft-rubber
Bt. On the inside of one of the caps is provided a standard marine
i-soeket for UO candle-power incandesoent lamp, to which is eonneoted
Mt of twin oondttetor cable, at the other end of which Is connected a
le pcde ploc for a standard marine receptacle.
len flrst sobmemd a considerable amonnt of moisture is deposited in
Bside. which is drawn oat through a small hdia made water-tight by a
r with a rabber gasket.
•••vclUirlito.
b reqnirementi of the standard Nary speeiflcatioDs are :
ihali, in general, consist of a fixed pedestal or base, sormonnted bT a
»ble carrying a dram. The base shall contain the turning mechanism
the elecmo connections, and be so arranged that It can be bolted
'cly to a deck or platform.
B tnrntoble to be so designed that it can be rcTolTcd in a horiaontal
» freely and indefinitely in either direction.
B dnxm to be trunnioned on two arms bolted to the tnrntable, so as to
a free movement in a vertical plane, and to contain the lamp and re-
ng ndrror. The drnm to be rotated on its trunnions. The axis of the
I to be OMMtble of a movement of not less than 70^ above and ao^ below
oriaontai.
B drum to be thoroughly ventilated and well-balanced ; to be fitted with
sights for observing the arc in two planes, and with hand holes to give
IS to the lamp. It must be so designed that a parabolic mirror can be
, and means tor balancing it m nst oe provided.
B mirror to be made of glass of the beet quality, free fkt>m flaws and
t, and having its surface ground to exact dimensions, perfectly smooth
dghly polished. Its back to be silvered in the most durable manner :
Uvering to be unaffected by heat. To be mounted in a separate metal
e lined with a non-conducting material, in such a manner as to allow
cpansion due to heat and to prevent Injury to it from concussion.
B lamp to be of the horisonUu carbon type, and designed for both hand
lutomatic feed. The feeding of the carbons must be effected by a posi-
mechanieal action, and not by spring or gravitation. It must Surn
ly and steadily on a 125^volt circuit in series with a regulating rheostat,
hall be capable of burning for about six hours without renewing the
ma,
I front of the drum to be provided with a glass door composed of strips
lar plate glass. The door to be so arrangM that it ean be put in place
e drum easily and quickly.
Slecirtcalljr Comtrolled JPTC||«ci«r.
be In all respects similar to the hand controlled, with the addition of
tiunt motors, each with a train of gears ; one motor for giving the ver-
tad the other the horisontal movement of the projector. The motors
ears to be contained in the fixed base, and to be well protected from
ure and mechanical injury. A means to be provided for quickly
ing out or in the motor gears, so that the projector can be operated
r by hand or by motor, as desired.
I motors to be operated by means of a compact, light, and water-tight
»ller. which^oan DC located in any desired position away from the pro-
'. Tne design of the controller to be sucn that the movement of a
t handle or fever, In the direction it is wished to cause the beam of
to more, will cause the current to fiow through the proper motor In the
r direction to produce such movement. The rapidity of movement of
rojector to be governed by the extent of the throw of the handle or
A suitable device to be included whereby the movement of the pro-
' ean be iivtantly arrested when so desired.
projectors to be finished in a dead-black color throughout, excepting
orUngiiMtfts, which tihaU, be bright.
1180 KLBCTRICITY JN" THB UNITED STATES NAT*.
SIGNAL LIGHTS. 1181
he lampc to be designed to produce the best results when taking current
ollows: 18-inch, 30 to 85 amperes; M-inch, 40 to 60 amperes; 30-inch,
9 90 amperes.
tie 18-inch projector shall project a beam of light of fuilicient density to
ler plainly discernible, on a clear, dark night, a lighVoolored object 10
D feet in slse, at a distance of not less than 4,000 vards : the 94-inch pro-
or, at a distance of not less than 5,000 yards ; and the dO-inch projector,
distaoce of not less than 6,000 yaids.
le connections for the electrically controlled projectors as manufactured
the General Electric Company are shown in the diagram, Fig. 5. The
Is of the two training motors are in series with each other and connected
»ss the 125-yoIt circuit. Both horixontal and vertical training can be
iltaneonsly produced. The controller-handle when released, is Drought
le oif position by springs and short circuits, both motor armatures thus
ping all movement.
le horizontal training motor drives through a worm gear, and the verti-
motor through a revolving nut on a vertical screw shaft : all gearing
be easily thrown out for quick hand control.
le highest speeds are 360P in 30 seconds horixontally, and 100** in 00
nds vertically. The motors may also be operated at four lower speeds.
le lamp has a striking magnet in series with the arc and feedinff
net in shunt with the arc. when the arc becomes too long, sufficient
ent is forced through the shunt feeding magnet to cause it to make its
Etture vibrate back and forth, and thus move the carbons together
ugh a ratchet which turns the feed screws. The point at whicn the
net will begin to feed is adjustable by means of a spring attached to
itnre. The feed screws are so proportioned that the positive and
»tiTe carbons are each fed toeether at the same rate that they are con-
3d, thus keeping the arc alwavs in the focus of the mirror. Sight
B are providea through which the arc may be watched. A permanent
net, fastened to the inside of the projector and sorronndlng the arc on
ides but the top, causes the arc to bum steadily near the upper edge
le carbons and in focus with the mirror.
e rheostat is located near the switchboard, and after being once set
•roper working does not need to be again changed. Doable-pole circuit
kers are used at the switchboards for switches.
e Ardois signals consist of four double lanterns, each containing a red .
i white Ugnt, which are hung from the top of the mast, one under the A
r and several feet apart. By means of a special controller any number M
ntema may hi^re either their red or white lamps lighted, thus produo- ■
ombinations t^ which an]r code can be signaled. The lamps used are ^
, and the color is produced by having the upper lens which forms the ^
of the lantern colored red ; the Ibwer lens is dear.
B controller consists of eight semi-circular plates, with pieces of hard
er set in the inner edges where needed, and a rotating center stud
eight plunger contacta rubbing on the edges of the plates. By suitably
ng the pieces of hard rubber for any given position of the contacts,
leeired combination of lights can be produced.
» operation consists in moving the ami carrying the contacts to the
ion desired (m shown by a pointer on an inaieating dial) and closing
perating switch, when the proper lamps will light,
ater design is provided witn a typewriter keyboard, the depression of
:ey making the proper contacts to light the lamps giving the combina-
M>rrespon<fing to the character on the key.
Track I<lghts.
> tmok lights are lanterns of construction similar to the Ardois
i^s, mounted, one on the top of both the fore and main masts. By
s of a special controller the red or white light in either lantern can be
td.
r
1182 SLKCTBICITT IN THK UNITED BTATKS NAVT.
Tia. (■ IMasTkm ol Ardoli SIfnal Bat.
POWXB 8Y8TBM. 1183
on an kept eniinly sepamte from lights by the om ci diffennt bne-
a the fenerator switohboard and distnbution boarda. Eaeh motor or
ci motoffB is supplied by Its own feeder running from the disUibtttion
when it has its own fused switch. A maximum drop of 6 per oeot
ired.
^
on to be wound for 120 volts, direct current, for both armatun and
rindinffi, unless otherwise specified, and to be either series, shunt or
•und wound, according to worlc they an to perform.
Ises above 4 hone-power, moton to be multipolar; 4 hoiBe-power or
may be bipolar. Itoton to be as compact and light as possible, con-
) with strength and effictenoy. The method of runmng wirss to
I to be in all cases by tapping conduit directly into the motor frames
) connection boxes attached to frames, as may be spedfied in each
lual case; connection boxes for enclosed moton to be wateivtight.
loeed moton should be provided with openingi of sufficient siae and
r to give easy access to brush rigipng, commutator, and field coib;
peningB to be provided with coven and fasteningi of approved desicn.
mtact surfaces between these coven and motor frame should be flat
aed surfaces, provided with rubber gaskets. Rubber gaskets for all
tight work to oe in accordance with the Navy standard specifications
i same as issued by the Bureau of Suites and Accounts. All en*
moten to be provided with drain plugi or cocks which will thorou^ikly
out any water that may enter the motor easing,
armatun shaft to be of steel and strong enous^ to resist appreeiable
ig under any condition of overload, to have sufficient bearing surface
» be efficiently lubricated by grease or self-oiUng bearings, or sifht-
il cups, as occasion may require. Oil cups to oe of sise to afford
ktion for at least eight houn. A satisfactory arrangement to be made
vent oU from running along^ the shaft or being spilled. Visual <m1
I to be provided for determining the amount of oil in pocket and
for drawing oil prior to renewal.
Mevent deteriontion from rust and corrosion, bolts for end brackets,
ts and inns one-half inch diameter or less not in the magnetic circuit
cb nuts and other special fittii^ as the Bureau may direct, will be of
Toeive metal, rolled bronae or its eauivalent.
ilectrical connections to be designed with special reference to the pre-
n of their becomini^ loose from vibmtion or shock. All connections
;o become loose by vibretion are to be provided with approved efficient
I devices.
Donneoting pieces and other current-carrying parts to be so propor-
tfaat no undue heating will occur when th/qr are worked under the
it possible conditions.
the field poles to be equally energised. In compound moton, series
unt windings to be sepante. The windings of armature and field to
1 protected from mechanical injury, and to be painted with water-
ing material not soluble in oil or grease. No insulating substances
ised that can be injured by a tempenture of 100 degrees C.
armature to be of the ironclad type, built up of thin laminated disks
iron or steel of the very best quality, having the spaces between the
>unohed out of each separate disk and not milled axter assembly,
disks to be properly insulated from each other. The coils to be prcf-
of the removable type, and to be retained in slots of the armature
ty maple wedges running full leni(th of armature, or other approved
1. No more than three band wires under poles will be accepted,
sires must be of nonmagnetic material. The armature to be electri-
nd meebanicidly balanced. The winding at pulley end to be pro«
from oil in an approved manner. The commutator segments to be
I copper, hard-dnwn or drop-forged and tempered. The segments to
mpie depth and insulated from each other and the shell by pure mica
i quality as to secure even wear with the oopper.
1184 ELBGTBICITT IN THE TTNITEB STATES KAVT.
Brushes to be of carbon; current density \^ brushes most al-u.
i^ven and should be in aeodrdance with th^ iMt practice. Special
tion must be given to the selection of brushes, that their material B-_
homogeneous and the quality such as to give perfect commutation «il_
cutting, scratching, or smearing the oonunutator. Brush bolden to
readilv accessible for adjustment and renewal of brushes and sprincs;
entirely of nonoorrosive metal and of the sliding shunt-eocket tvpe» in
the brush slides in the holder and is provided with a flezibre eodun _
between brush and holder. The springs are to be phosphor>braue
shall not be depended on to carry current. Brush holdan oo aU
be adjusta1)le for tension, and 'on motors of nve-horse-power and abowtsl
be adjustable for ten«on unthoiU tools, and so constructed as to permit rf
g roper staggering oi brushes. Brush holders for nonreversible motoo of
ve-horse-power and above to be simultaneously adjustable for postiaBi
Proper position of rocker arm to be plainly marked. Tliis pontioa ki
reversible motors to give same speed in either direction.
Gontraoton are required to afford facilities for inspection of
during manufacture, if required.
Individual motors or small lots will be tested at the point of deliTcry.M
all large lots of materials to be shipped to distant points will be tested at te
works of the manufacturer. The contractor will provide all faeilitieB» mi
have all the required tests made in the presence of an authorised inspadBK:
The contractor will present a certified record of such tests with the ifaiv-
ery. The tests to cover the following points:
(a) A4|«stme»t mnA WH of Parts. ~ The inspector to see that A*
materials and workmanship of all parts of the machine are of the bait
quoiityand satisfactoiV in evenr respect.
(6) nlecluusicAl mtr^mg^tm. — The base, bearinn, shaft armatuze. id!
magnets, and other main parts should not spring with any reasonable foiii
that mav be applied to them. The strength to resist strains due to es^
trifugal force to be tested by running armature without load for 30 mlns'—
at double its rated speed for shunt motors and four times full load tv^
for series motors.
(c) B«lttBce* — The perfection of balanee of the armature to be tested
by running the motor at its normal speed, at which 8i>eed the motor m«t
not show the slightest vibration.
(d) If olse. — The motor to run at its full-rated speed and load withoel
noise.
(e) Sparlcliiir* — Open motors to run without sparkinfE from no load to
full load without shifting the brushes and under all conditions cS full ssd
weak field when fidd regulation is used. Enclosed motors to 25 per csst
overload.
(/) V«ria.ti4Mi of 0p««d. -^ For shunt-wound motors the variatica »
speed from no load to full load shall not be more than 12 per cent in molsB
of less than five-horse-power and not more than 9 per cent in motors oC flw
horse-power and above. Series and compound wound motors to make it
rated outputs their rated speeds. The motor should be designed to oMi
its rated speed when hot, with atmospheric temperature of approzimrt^
25 degrees C. and the speed actually obtained on test at the end of W
heat run must be within 4 per cent of the rated. The variation in npm
due to heating shall not exceed 10 per cent. ■
(g) IMelectrIc itrength. — The test for dielectric strengtb to beoaife
with a pressure of 1,500 volts alternating E.M.F. for 60 seconds, tested «A
a generator or transformer of at least 5-kilowatt capacity. The iosdslM
resistance between windings and frame to be at least one megohm iiiianiww
with fiOO volts direct current. . ^ . , . ,
(h) Heattnr* — The rise of temperature cf the field wmdinsi aboiv ttt
surrounding air is to be measured by the resistance method acoordtafto
the rules and coefficients adopted by the American Institute of EMnatt
Ehgineers. appended. The rise of temperature of all other parts to tehy
thevmomstsr. The temperature of the room is to be read fram ''
meters, conditions of ventilation being normal.
1
POWEB 8T8TBM. 1186
iw following an the maTrimnm temperature rieea allowed:
i) Open-type motors desicned for continuous work, eight hours' run
with a rise of —
Commutator, 40 degrees C.
Field winding, 40 degrees C.
All other parts, 35 degrees C.
i) Enclosed motors designed for continuous work, eii^t hours' run
with a rise oi —
Commutator, 50 degrees C.
Field winding, 50 degrees C.
All other parts, 45 desrees C.
i) Intermittent-running moton wiu have heating limit and length of
heat-run separately specified for each ease.
le temperature rise of bearings shall in no case exceed 35 degrees C.
MBctomcj* — Motors must have the hii^est oonunerdai efficiency
heir sise and speed. Each eon tractor must state weight and effieiency
loton at one-quarter, one-half, three-quarters, and full load. Prefer-
will be given to liiptest weiJEfat and best effieienoy consistent with
design and the speeifio requirements. When thorough reliability and
lom from danger of breakdown are the prime requisites, as for turret-
ing motors, boat-erane motors, etc., the i«**<»«i»m efficiency will not
isisted on.
> JLabrlctttlon. — The inspector will see that oil cups and wells of
ipecified capacity are provided and that all the necessary provisions
oade for the supply and drainage of oil without injury to toe electrical
I.
eotric brakes, solenoids, ete.. to stand the same heat and insulation
as the apparatus to which they are attached. All spare parts to be
leted to the same tests as origiiuUs.
Mt intermittent running motors, such as boat crane, deck wineh, turret
ng, etc., have the following heat tests:
icb motor shall be tested at the works of the maker by running for a
Auous period of one hour at 120 volts at its rated output and speed,
rat increasing the temperature of the series field windings more than
agrees C, the shunt field windings 50 degrees C, the connmutator 65
na C, the armature or any other part 60 degrees C. above the sur*
iingair.
JPrlMdpttl ]K«4«lre«ie»ta f*r Go«trollliir IRmmmU,
strolling panels for installation in locations not exposed to the action
ater outside cf ammunition passages, handling rooms, etc., where
er is handled, ma^ be of the nonflaroe-proof type, in accordance with
lUowing specifications:
B panel to consist <^ a suitable insulating slate base with black polish
, canying a double pole main-line knife switch with enclosed indicating
a starting arm with automatio no- voltage release and overload cir-
ireaker and the necessary resistanoes mounted at the back. A double
eirouit breaker with independenUv operating arms may be substi*
for the line switch if desired. On panels where speed control by
resiatanoa is required, suitable rheostat connections are to be pro-
, giving ample number of steps to secure smooth control and accurate
tment, and must be a separate multipoint switch so arranged that
lotor oannot be started on weak field. On panels where speed con-
•y armature lesistance is required, the starting arm must be so con-
ad that it will stay only on the contacts designed for continuous
ng.
' motors requiring more than 60 amperes of current, the starting arm
not be r^ied upon to carry the current in the running position. The
Ag peeiatanoe must not be left in series with the field on the running
E>n ; oomieetions to be such that there shall be no disruptive discharge
I field on opening the oircuit. either by opening the main-line switch,
forcing ih» starting arm to the off position, and provision to be made
ivent areing on the initial starting contact. Panel to be so connected
i ahall be impossible to have full voltage on the field with the starting
1186 ELECTRICITY IK THE UNITED STATES NAVY.
arm in the off position. Care should be taken in the dcsisn oC the
to see that there is no interference between operatins parts, such i
switch, when opened, and starting arm. AU magnet ooik and all
parts carrying currents must be renewable from the face of the paod
out disturbing any of the rear connections. Pand to be mounted oAa
rigid box metal frame, with the top and bottom of solid sheet mctsl
the sides (if so desired) ol perforated metal, which must extend the li
and breadUi of the slate and which must protect the connections and _
back of the panel: suitable lugs or extensions to be provided for snpoert-
ing the frame. Hinged doors with composition lock and duplicate bhi
shall be provided over the face of the pand. No part oo the fmoe cf vt
panel is to project beyond the edge of the panel.
The automatic no-volta^ release must operate and either bring tht
starting arm to the off position or opm the circuit breaker upon f silme sf
voltage. The windinc of the no-voltage release magnet muet not hs
put in series with either the field winding or armature rewiirteme Ita
automatic overload release must be of the nature of an ordinary s|
operated circuit breaker, having the release mechanism operated h^ a
tive hammer blow, delivered by a core or armature moved mgm
action of gravitj, and must have its own independent oooUtots for
the armature cirouit; and it should open the cireait m case of 01
under any oondition, i.e., during ordinary running, during the act d
ing the motor, or if the starting arm should become struck on any
point and the ourrent then switched on from the outside. Por
having a rated full load current of 50 amperes or less, the overioAd
nutv be of the interlooking type, in which esse it must be so interoo
with the starting arm that it cannot be closed with the starting
any but the off position. For motora requiring nuMe than 50 ami
single or double pole dreuit breaker entirdy separate from the
arm muit be used. An overload device vriiioh operates by sbort-eireaitiM
or opening the drouit of the retaining magnet of the no-voltaoe
under no conditions be accepted. The overload device is to be providsi
with renewable ardng oontaots of carbon, to be adjustable and pitj^iitBi
with a scale graduated from normal current to 100 per cent overload ts
facilitate adjustment to the dedred number of amperes, and to be abfe to
carry a ourrent of 00 per cent in excess of the rated full-load motor ewrcsi
oontinuoudy without undue heating. The tripiMng device moat be able to
withstand severe shock without opening.
The insulating material used on the iMmd must be noneombustible, noe-
absorbent, and not damageable by moisture or by heating to a tetnpsta*
ture of 150 degrees O. The frame of the pand is to be insulated from the
hull of the ship. All paneb are to pass the same dideetrie and insnlatkn
tests as the motors for which they are supplied.
All windings of magnet ooils are to be run throngh an insulating varaiA
and the outside of the coils to be wdl varnished ana taped. When oontxne'
oudy in drouit, the temperature rise of these ooils must not be mote
than 40 degrees C. above surrounding atmosphere, measured by tiisf
inometer ^aced on the coil.
The main operating springs for the no-voltage rdease and the oveilced
dreuit breaker must be amply strong to prevent any sticking after tfa
appliance has become worn or roufi(hened. All flat springi are to be d
pnosphor-bronxe and all helical springs of oopper>plated sted. AU eo»>
tacts to be easily renewable from tne face oi the pand. The etreuit is aet
to be opened on the rheostat contacts, and spedal arrangementa to fct
made for opening the dreuit and rupturing the arc independent of
contacts. All sliding brushes to be easilv renewable and of the i
ing, sdf-adjusting type, and able to ride over any projections
one-dxteenth of an inch above the contact segments.
All operating parts to be strone and very substantial; thin ^
stampings are not to be employed. All such operating parts which earrf
current to be copper or composition. Where the employment of oxkBasUe
metal is necessary for magnetic purposes thdr surfaces shall be tfaoioaghly
protected against oxidation by copper-plating. Where used for other pap>
poses to be very heavily coated with a nonvitreous enamd. The ooataet
points to be of composition or copper, ample in dse and wdl fitted on ilM
surface and eadly renewable. Pands should be as small and ^'-^^
dble, consistent with other requirements.
POWSB SYSTEM. 1187
in nsistaneea and all insulation used on them and their oonneetins
CB must be noncombustible, and the connecting wires must be capable «
rying their full current under ail conditions of test and operation without
loming dangerously hot. All resistances to be of the unit type, so eon-
icted and instdtted that they may be easily replaced and the whole
ostat readily removed from the casing. The method of mounting and
tilating the resistances is to be such that the result of a bum-out
iild be practicflJly the same as would occur with an entirely enclosed
btance, and no resistance is to be used until a sample has been submitted
the Bureau for test and approval. The capacity of aU controHing panel
stanoes must be obtained without placing the coils in parallel with each
er, unless eadi is capable of carrying fuU-Iine voltage. Starting resist-
es when cold must be capable of carrying 50 per cent overloaa in cur-
t for one minute, and 100 per cent overioad for twenty seconds. Incan-
oent lamps or carbon shall not be used as resistance. Resistances must
mounted at the back of the pand upon the supporting frame, and not
Bctly on the panel, for motors having a rated fuU load current over 50
peres. For motors requiring 50 amperes or less, the resistance may be
Mported from the back of the pand bv suitable brackets, if desired.
Ivater-tight, flame-];>roof panels will be used as directed in locations
atly exposed to moisture and where powder is handled, as ammunition
sages, handling rooms, etc. They will, in general, consist of a cast metal,
ter*tiffit, flame-proof case containing the necessary resistances, con-
tions, and operating parts, which must be controlled from without by
■ns of rods or levers passing throu^ approved stuffing boxes. The
lels must contain within the casing at least the following parte: Rosist-
les, circuit breaker or overload release, no-voltage release, reversing
tch (when required), starting arm and contacts, and the necessary field
tacts when necessary for variable speed motors. They will conform to
requiremente for nonflame-proof panels as reimrds connections^ capacity
lesistanoe, construction of overloaa and no-voltage release, springs, con-
ts, etc., but such deviations from these requirements as may be absolutely
eosary to simplify the construction of the panel and reduce its sise and
^t to a minimum will be considered.
lie panel will be provided with suitable removable covers provided with
nping devices of approved construction, made water-tifcht by means of
ber gaskets, which will permit easy access to the interior. It must be
mg and substantial in design, but ot lightest weia^t and smallest dimen-
is consistent with other requirements. Suitable Ixmses for tapping
duit into casing to be supplied, the casing to be drilled and tappecT after
verv. The casing Is to oe sufficiently water-tight to permit of immer>
I without leakage. Nonoorrosive metal requirements will be strictly
ered to, and aU operating levers passing thit>u|^ stuffing- boxes will be
omposition.
lie following are the requirements of turret control:
'ini. Turrets to be able to be turned at a maximum rate of 100 degrees
minute, and at a minimum rate not exceeding one-fourth of a degree
minute, as large a number of speeds as possible (not less than 50) to be
inded between the limits of one-fourth and 22 degrees per minute and a
ident number of speeds between 22 and 100 degrees per minute to per-
of smooth and easy acceleration. The total number of speeds to be
leas than 70.
econd. Turret to be capable of acceleration at such rate that it can
Parted from rest and brought to its full speed of ICN) degrees per minute
sn seconds of time, and while turning at its full speed of 100 degrees per
ute to be able to be stopped in five seconds of time.
Mrd. At aU speeds between and including ono-fourth and 1(X) degrees
turret is to turn continuously throughout the arc of train on each con-
ler position with practically no variation in speed due to increased load
he motors caused by allowable irregularities in track, gearing, etc.
ourth. Turret to be able to be started and stopped ten consecutive
98 without turning throu^^ a total arc of train greater than five
utaa.
1188 SLECTBICITY IN THB UNITED 8TATB8 KAYT.
There are four different systeme in use at present:
1. Ward«Leonard System.
2. Rotary Compensator System.
3. Differential Gear System.
4. Mechanical Speed Gear.
1. The Ward-Leonard System was used on the first electrieaOy opcniil
turrets in the Navy. The actual connections and elementary aia^am of
the installation on the " Illinois " are shown in Fie. 2.
The motora are shunt wound, and have the fields constantly aepaiat^?
excited from the bus-bars of the ship's power system. A separate geaeatat
is required which cannot be used for any other purpose when used with the
turret. The generator is also separately excited from the power l>iie-bs0,
but a variable liieostat, located in the turret, is connected in the shosi*
field circuit. The brushes of the motor are directly oonneeted to tfai
brushes of the i^nerator, and the generator is keot runninf^ at eaaetsat
speed by its driving-engine. It is now evident that oy varying the ilieoslBt
in the turret, the field excitation, and consequently the voltase prodaad
by the generator, will be varied; and any^ variation in the v^tace of the
generator will produce a corresponding variation in the speed of the bm^ot.
which has a constant field from separate excitation. The direction of ictt-
tion of the motor is reversed b^ reversing the leads to the armature. Th*
actual connections for the application oi the above principles are abowa is
the main part of the diagram. Generator No. 4 is shown oonneeted lor
operating ue after-turret.
Closing the after- turret field switch and the center blades of the senemor
field switch separately excites the fields of the motors and generator fraa
the power bus-bars. The regular field rheostat of the generator is entirely
disconnected, and a rheostat located in the turret and operated by the tar>
ret-tuming controller is used instead.
Closing the positive and negative single-pole switches on the af ter-cairsBt
bus-bars connects the generator armature to the motor armatures, thnmgli
a circuit breaker, the reversing contacts of the controller, and sepaiats
armature switches for each of the two motors, which are operated is
parallel.
The controller has one shaft, at the top of which are located the cos*
nections for the generator field rheostat, so arranged that as the oontrofiv
is turned either way from the off position the rheostat is gradually cut cat;
below are located the revening contacts, which reverse the conneetaoss
between the generator armature and the motor armatures; these oontai^
are so arranged that at the off position the motor armatures are enlirejy
disconnected from the generator, and are short-circuited throuffa a lev
resistance called the "Brake resistance.** The effect of this brake remft-
ance is to bring the turret to a quick stop when the controller is broufkt
to the off position, as the motor armatures revolving in a separately exched
field generate a large current, which passes through the braking resiit-
anee, and thus absorbs the kinetic energy of the turret, giving a quidc and
smooth stop. In parallel with each oT the large main finseis of the re-
versing contacts is a small auxiliary finger and an auxuuuy resistaBCS
connected to it. This auxiliary finger makes contact a little before sad
breaks it a little after the main finger, and thus reduces the spa^asfr
The controller is also provided with a magnetic blow-out for redncnf
sparking at contacts.
When used on this system for operating a turret the generator has ¥m
series coil short-cirouitea by a very low resistance shimt, so that it has veff
little effect on the field excitation, but this resistance is so proportioBid
that enough of the total current generated by the generator will pass throe^
the series coil to give a quick and positive start of the turret; beuauss i
the series coil is absolutely short-circuited, and only the separately cxdtsd
shunt coil used, the time required for the field to ouild up is sumeieat to
make the starting of the turret very sluggish and irregular, and prevsalt
very fine training from being obtained.
It is seen that the above-described arrangement requires a separate it-
erator for each turret, and while operating a turret no power can be taksa
from the generator for any other purpose. The first ships to use eleetris
turning gear had only two turrets, and two generators can easily be aUowed
FOWSK 8Y8TBK.
1189
turret turning; but on the latest Bhips aiz turrets are used, and it is
y undenrable to allow six generators for this purpose. To overcome
I objection the Ward-Leonard method of control is obtained by means
i motor generator located at each turret, all of which take power directly
m the main bus-bars of the dynamo room, thus materially reducing
reciuired generator capacity. An elementary diapam of the airange-
Qt is shown in Fig. 7. It will be noted by comparison with Fig. 2. that
y two instead of five wires have to be run from the dynamo room to
h turret,
lie Ward-Leonard system will not give the large range and low speeds
At
QroMao Boom aa4 Tujsl
Fio. 7. Diagram of Motor Generator on Turret-Turning System.
r required by the Navy Department and therefore the other above*
itioned si^stems have been devised.
. The Rotary Compensator System is shown in Fig. 8. A and B are
armatures of a motor generator balance set. called a Rotary Oomi>en-
»r Set. L is a large shunt motor geared directly to the turret. S is a
11 shunt motor the shsft of which carries a worm. Wl. working in a
m wheel. W2, mounted on the shaft of L. This worm wheel is pro-
id with a magnetic dutch D so that it can turn f redv on the shaft of L.
le held to it. C is a contact in the controller which opens one side ot
armature dreuit of L. R is a field rheostat for A and B and is operated
Jie controller. With the connections ss drawn in the dianam. B has a
Ic field and a low voltage, thus driving S at a low speed ; ^ is driving L
ui^ the magnetic dutch aini worm gear and thus turning the turret
very low speed; Gis open, so L turns fredy, and does no work. As the
roller is turned R is gndual^ inserted in the fidd of B, thus increasing
iroltage and increasing the speed of S. When B has full field the mag-
3 duteh is opened and C is closed, thus transferring the load from S to
idpermitttncS torunfree. At this time A has weak fiekl and supplies
r voltage to L. and further movement of the controller brings the arm of
ick to the first pontion, thus increasing the voltage of A and the speed
^until A has full fidd and the turret is turned at full speed. At the
>d of transition when the load is shifted from S to L it is necessary that
ratio of the speeds of S and L shall be the same as the ratio of the
ngearing by wnich S drives L. so that the transfer will be made smoothly
without shock or change in speed of turret. In shutting down the
'0 actions occur in reverse order. Reversing is accomplished by rever-
the armature loads cf the two motors, and in the off position
armature of L is short-drcuited to produce a braking effect: these results
tocomplished by oontroUer contacts similar to those for Ward-Leonard
am as per Fig. z. This system is made by the General Electric Company.
1190 BLECTBICITY IN THE UNITED STATES KAVY.
Fio. 8. Rotary Compensator Turret-Tumins Systflm.
3. The Differential Gear System is shown in Fig. 9. L and S are .,
ively l&ree and small shunt motors running continuously on tike supply
main. They are both directly geared to a differential gear which is ao pco*
XMrtioned that with L running at full speed and S at weak field the soil
A will stand still, but any change in their relative speeds will oauae A to
n eeman
[
:^
DirF£REMTrm. GeAR
Pio. 9. Differential Gear Turret-Turning System.
rotate at a speed proportioned to the relative change. This chann ia
relative speed is produced by the field rheostats Rl and R2 whidTaie
pperat^l by the controller, and first decrease the speed of S by strengtheeiBC
I? # ,.' *'*° ^y^^ increase the speed of L by weakening its field, thus cmM
the full speed range of the turret. The shaft A is geared to the tomt
through the gears Gl and G2, each of which is provided with a masDotis
AMMUKITION HOISTS. 1191
teh CI and C2. G2 ia geared direct, and Ql throush a reveiM cear,
a aooomplishing the revening of the turret motion. The magnetio
tohes ate operated br oontaota on the oontroUera. Thia eystem Is made
The Cutler-Hammer ICanufaottuing Company.
:. The Meohanioal Speed Gear System uses a oontinuooaly running, con-
st speed, shunt motor geared to the turret thxovu^ the speed gear. The
ad gear consists of a variable volume oil pump and an oil jnotor mounted
ft common casing and provided with mechanical means for varying the
ome of oil d^vered by the pump per revolution and ita direotion of
r. The speed gear is made by the Waterbury Tool Company.
n all the above systems two sets of raoton are usuaUy provided and
ftnged so that by means of switches either set may be out out ami the
ret operated by one set. Turrets carrying two 12-inch guns usually
'e two 2&-horBe-power main motors, and S-inch turrets two 15*4orse-
vet motors.
IioadlMr »Ml Tmtmlnc C}«Ar for
fUns of 8-inoh and over are elevated and rammed by power; smaller guns
^ handcar.
Three kinds of elevating gears are in use:
1. Plain rheostat control with series motor.
2. Ward-Leonard control.
3. Mechanical speed changing gear with constant speed, shunt motor.
Iheostatic control with series motor as used in the first vessela does not
B suffidentiy close and even control. A 24-hone-power, 300 r.p.m.
tor with plain drum-reversing controller is used.
Vard-Leonard control as usm is similar to that used for turret turning
shown in Fig. 7. The control obtained is quite satisfactory, but Uie
iplication is objectionable and there is not suitable space available ia
turrets for the motor generators. Ten horse-power elevating motors
I eight K.W. motor generators are used.
lie latest vessels are using constant speed shunt motors and obtaining
control by means of mechanical speed gears as described above for
ret turning.
tammen consist of a telescopic tube worked through spur and chain-
ring by a 5 H.P., 775 r.p.m. series motor. A friction slip clutch is
irted in the gearing to prevent damage when the shell seats itsdf in the
9ch. Ordinary rheostatic control is used.
Hien ramming a shell but little power is required, as the shell slides
ig the breech, out as it is being forced to its seat at the end of the breech
mber a sudden rush of current of from two to three times the full-load
"ent of the motor is produced.
AMnrcriHntTioif hoiatb.
ower ammunition hoists are of two kinds: first, those In which a car
age is hoisted up and down by a line wound on a drum on the motor
iter«haft; and second, those in which the motor runs an endless chain
rided with toes or buckets on which the ammunition is placed and con-
xl up through a trunk.
BEoiete for IS-tecH muA IS-lncli JLnunumiUam.
{
heee hoists are of the first kind. The motor frame is provided with
ings for a counter-shaft, geared by a spur-gear and pinion to the arma-
shaft; on the counter-shaft is mounted a grooved drum for the hoist-
cable.
n the armature shaft is mounted a solenoid band-brake. The cores of
solenoid are weighted and attached to the brake-setting lever so that
n free their weight is sufficient to hold the loaded car from falling;
n the solenoids are energized the cores are drawn up and the brake ro-
ad.
he controller is constructed so that on the off position the solenoids are
energised and the brake is set; but at all other points, both hoisting and
(ring, the aolenoida are energised and the brake released.
1192 BLSGTBICITY IN THE UNITED STATES ICAVT.
(Ettiimi moton are used, and the control for lioistinc is ^
the rabtanoe beinc put in serieB with the armature and sradoally cut
the field is always oonstantly excited as soon as the feeder-ewitcfa is '
For lowerins. the entire rheostat is thrown directly aoroas the Kas^ oasj
armature lead oonneeting to one side of the tine ana the other load snd^^
ally moved (as the motor is brought to full speed) from the eondition ef a.
short-dreuited armature at the oft position to direct conneetioii to the othv
side of the line at the full on position; in all intermediate posstioos Ihi
armature is in shunt with a part of the rheostat. The ohjeot of tfaia is is
cause the armature to take current from the line and run as a motor
lowerlng a li^t load which will not overhaul, but to run as a itnuwfii
send current throuj^ the rheostat if the load is very heavy and oi
the motor and gearing. In either case the speed will d^Mnd upon Iht
amount of the rheostat that Ib in shunt across the aimature. The off .
tion of the oontroUer short-circuits the armature, and since the fields aic
always excited, this gives a quick stop and also holds the load.
The 13-ineh hoists of the U.S.S. "Kearsarge" and '* Kentucky'* iMeSO
H.P. motors running at 360 r.pjn.» with a gearing ratio of 6.43 from anw
ture to counteivshaf t.
The load was, empty car 1,846 pounds, and full charge 1,628 poonds, crs
total of 3.474 pounds.
The following average results were obtained when testinc b hoiatiag fdl
ohaive:
Hoisting-speed, feet per minute 18D
Mechamoil H.P. in load 18.96
Input of motor, E.H.P 28.5
Total efficiency 66.6SS
Moton were designed to be suspended under the turret, were entirill
enelotedy and weighed 3,000 pounds complete with brake.
Holate for •-Inch Aaini«Bilti«n.
Hoists for smaller ammunition are made and controlled In » ■"•*—>
similar to the above.
The 8-inoh hoists Jued a 6 H.P., 375 r.p.m. shunt motor to hoist a totsl
load of 910 pounds at 163 feet per minute.
Tests gave average results or—
Mechanical H.P. in load . . . . 4JS
Input of motor, E.H.P 7.4
Total efficiency 60.^
■Mdleae Chain Ajnninnltlon H«lirta.
These hoists run continuously, the ammunition being fed in as desired.
The motor is geared to the chain sprockets by spur gearing, is shunt wound
and is started and stopped by a controlling panel, which la provided with
no-voltage and overload release, and a reverslng<switch.
A solenoid brake is mounted on the armature shaft, and is set when tie
starting-arm is in the off position, but has its coils energised and is released
when the arm makes the first contact in starting^ At the full on poeitica,
part of the starting rheostat is in series with thebrake, thus cutting dovs
the current consumed by it. This does not affect the reliability of tk«
brake, since the current required to hold up the cores is much lees thss
that required to first start them, and at the start the full-line voltage li on
the coils.
To lower ammunition the reverslng-switeh Is thrown down, whi<di re-
verses the connections to the motor armature, and puts in U>e armatsre
circuit a safety switch. This safety switch is attached to the lever whidi
operates the catch pawls in the hoist trunk. These pawls will allow arane-
nltion to go up. but will catch and prevent it from going down, ai^ ars
used to keep the ammunition from falling in case any part of the hoist
should be shot away. When the pawl lever is thrown down It throws the
pawls out of action, and allows ammunition to be lowered by rerersing the
AMHDMITIOK HOISTS.
■otor ; It iilaa oloMi tba *B(«Ir ivltch which compUtM th* unuitDT* d
init for thaloveriuEPiMltlooor tha tfiT«nliig4witch.
Tbl( It jia ot hoUt & and lor all klndi ot unmnnltioD Bp to uid Inclndlni
■etori tztau 2| to S U^. i
I
nonltioti from Mime niB[Ulii» to the loot ot theboiit. Tba eniUeat
In la taoriioirtal, uid no btske or Mfetf awltoli li nMd.
1194 ELECTRICITY IN THE UNITED STATES NAVT.
For handllDg tteun ouCtan and other htatt ■ nvolTlne er«ae bafiu ttt
1 -w . . J — ■. J . . ,. „t«ini> down to tEe jvotaetiia on*.
i ciroulaf piatfonu fuieusd to tie en
central ahapt ol • davit l> iu«<l ; It •it«Dilg <loim to t£e prDtaetiia lid.
AOd luu BiteiMW bearing at each deck paased through, and the *ei^i i
oarrlad by a rolfor Ihruit boailng. Tho oporalinj macUli ' ' "
titeady bearing at each deck paased through, t
Ifonn faiMned to tEe crue.
rdiiwclflcallonB require Cbefolluwingoontrol to be obtained:
«(loiu between motor and controller to he aiKttW
■ obtained
tbe followtaic reHnlla
I. Nofnalble con
afcijeultbrSakar,oi
Via. 11. Diagram ot Connectlaai for Boat Crane IfoMn.
II. The load to alsajra atop and ha held 11111 fmmedlately wbao Um*"
IrolUngorDperatlngleTerlatrouabt to the otT poiltlon during hal<>li>l°'
lowering. The alee trk brake lieslf O" cane of failure o[ meohanicaltnl')
to he of aufflolent power to alop anil bold ^e nnulmum load ai tl» »
potltlon or upon faflnra o( currant. . ^
lU. Haiimum laad not to lower while the eontroller operattug lererlil*
any halat position.
The control of the rotating motor mnat glTe the rollowlng result* :
IT. Smooth atariliig ainl stopping niiuT he obtained under all condlM*
ot load aud apeed.
VI. Svli«fng or the luipeiKed'loadur rolling of theahlpm
duce dangerona or exoeailTa Tarlatloaa In tbe rotating apead.
ontrellcT ofxralW
BOAT CBANSS.
1196
dintfilT two motions are prorided, rotating and hoisting, and a tepa-
motor 18 Qsed for each ; h«t eometimee a tvoUey Is used so that the Imul
be mored radially ; when used the trolley is operated from the hoisting
>r, which is then proTlded with a ohange cluton in the gearlBg.
lin series motors are used. The hoisting motor is nsitallT geared to th4
1 by one pair of spars and a worm, the worm wheel being fastened to
Irnm. and the pinion being on the armature rtiaf t. At some oonrenlent
k in the gearing an automatic mechanical brake is inserted, which will
allow the loacTto lower when the motor is run bv electric power in the
ring direction, and which absorbs the energy of the lowering load In
ton. The design which at present has given the best results Is that
; friction disks and a foUow-up screw similar to the brake used in the
;on triplex pulley block. A solenoid brake is also mounted on the
iture snaft, which sets at the off position of the controller. The rotat-
lotor is similar to the hoisting motor, but smaller. Cranes are required
tate at the rate of one reyoluiion per minute.
s slses of motors used on the usual capacities of oranee on the latest
Is are as f<^ows :
C/apaeity
of
jie Pounds.
H.P.
of Hoisting
Motor.
H.P.
of Rotating
Motor.
Hoisting Speed,
Feet
per Minute.
93,000
17,000
10,000
6,000
50
30
80
20
ao
2t
20
15
26
26
40
40
ts on typical cranes gaTe the following results :
[ioad.
£in.
H.P.
in
Load.
Motor
Input,
E.H.P.
Ei&oiencies.
Weight
Rotated,
Lbs.
Motor
Lbs.
Total.
Motor.
Qear-
ing.
LTk
9,000
B,ooa
9,300
29.7
21.1
S1.0
17.1
18.1
9.67
29.7
27J
19.3
67.6
47.0
60.1
86.
82.
82.
66.8
S7.8
61.1
82,000
72,000
46,000
1.46
.80
1.86
16.4
14.8
9.9
of the aboTe cranes hoisted the load by a two^art tackle, and the
I of the gears were :
1. Pinion 22 teeth, gear 70 teeth, 1^' pitch, 4^' face.
Worm triple threaded, 32" pitch, O.O'' lead, 121^' P.D.
Worm wheel 42 teeth, drum dia. 29^".
360 r.p.m. of motor =30 ft. x>er mln. hoist.
2. Pinion 19 teeth, gear 87 teeth, 1|'' pitch, 4" face.
Worm triple threaded, 3" pitch, 9" lead, 12^ P.D.
Worm wheel 33 teeth, drum dia. 24".
400 r.p.m. of motor = 26 ft. per mln. hoist.
This erane had also a pair of miter gears of 18 teeth, 2f* pitch,
6" face.
I. Pinion 29 teeth, gear 63 teeth, 1|" pitch, 4" face.
Worm triple threaded, 2" pitch, 6'^\eadj 9" PJ>.
Worm wheel 67 teeth, drum dia. 26i".
800 r.p.m. of motor = 30 ft. per min. hoist.
1196 BLBCTKICITY IN THE UNITED STATES KATY.
The usmal design of eleotrlo deck winch oonslste of a series moior l
"by spur gearing to a shaft carrying a gypsy head, all beins mounted eai
suitable t>ed-piate. Fart of the winches on a Tessel nsnafly hnTe dum
gears |iying two speeds, which are operated by clutches. Tne asnal<
city is 2,200 pounds' pull at a speed oi aoo feet per minute, and on wii
haTing change gears the low speed is 13,000 pounds at 00 feet per i
A friction band brake operated by a foot lever is used. RheostaUe
is used, with a rerersible controller. Motor and oontroller are both
tirety water-tight, and will stand a stream of water from the fire bone. *
rheostats are mounted in the bed-plate, or else in a water-tiglit Iron box.
The usual method of operation is to run the winch conuniioutsly st f
speed in one direction, and then control the hoisting and lowering of
load by taking a suitable number of turns of the hoisting rope aronnd _
revolTing winch head. Very good control of heary loads can ne obtainsd I
this manner ; but if much lowering of heavy loads is done, dlflleQlty vfll f
had with the winch heads becoming hot.
On single geared winches haying but little friction In the searing.
speed of a plfin series motor at no load would be dangerously nigli, ant
overcome wis a small amount of shunt winding is added. On tw
winches the initial friction is usually enough to prevent dangeroos
speeds.
30 H.P. motors are used on both of the designs*
in
▼■MTU.ATIOM WAJtB.
Nearly all compartments of a ship have artiBoial ventilation by
ally-driven fans, usually operating on the Dressure syston, but in
eases exhaust fans are used. All of the huD ventilation fans a
but the forced draft fans for the boiler rooms are steam diivi
cases, althoufl^ a few of the Inter vessels have electric drive.
Fans are driven by shunt motors, usually of the opm type, but in
exposed locations entirely enclosed motors are used. Full speed of
is that required to make the fan deliver air at 1^ ounces per square
pressure, and speed variation down to the speed giving 1 ounoe ia reqi
which is a reduction of about 20 per cent. This speed variation ia obtL^
by field resistance on motors above 1 H.P., and bv armature resiatanoe
smaller sises. Controlling panels are used which have the neoe
stats for the speed control, and also overload and no-voltage reli
PiiMdpal ItequireaseMta for TmstHattar
The following may be considered as standard capacities for Tontilatiiv
fans and will in general be specified:
600 eubie feet.
1,000 cubic feet.
1,600 cubic feet.
2,500 cubic feet.
4,000 cubic feet.
5,000 eubie feet.
6,000 cubic feet.
8,000 cubic feet.
10.000 cubic feet.
12.000 cubic feet.
All fans to be built up of sted plate with the exception of the 000, I.O0QI
and 1,600 cubic feet, imich must be of east shell oonstruetion. Fana to be
practically noiseless and to be of the convertible tvne so eonstructed tbst
they will be suitable for either right or left hand and for at least ei|dit differ-
ent angles of discharge. Cast shell fans to be so eonstraeted that tk^
may be installed on deck, on vertical bulkhead, or sospended frocn dsK
above. All fan wheels and the interior of steet-i^te fan '^'^'^pi to be
Klvanised to prevent corrosion. Interior of casings of cast shelTfaos to
thoroughly coated with asphalt um. Fan wheds to be of steel, keyed on
shaft with set screw in hub; hubs to be brass bushed; cast shell fans to be
of heavy, soft, cast iron, free from all cracks, blowholes, or other defeets. and
suitably re-enforced at all points of strain. A hand hole to be provided in
^
YBNTILATION FANS. 1197
ins of all cast shell fans for aoceas to set seraw in hub of wheel; cover
this hole to be finished and made air-ti^t without the use of putty or
ilar substances. Scrolls of steel-[>late fans to be in three removable
tions. Each fan to be provided with a name plate (dving the capacity
subio feet per minute. Inlets and outlets of cast sheU fans and inlets df
il-plate fans to be circular in shape, outlete of steel-plate fans to be
tangular. Area of fan inlets shall not exceed area of outlets, the inlet
be straisht, and no temporary means shall be emploved in any test to
ace the friction of the inlet. After installation on shipboard, the fans
ye provided with suitable drip pans with cocks.
Saen fan with its motor and controlling panel to be assembled and tested
the works of the maker in the presence of a government inspector, suit-
B means being provided for measuring all data.
n maldng shop tests the set shall be erected with free inlet to the fan.
ire shallbe attached to the fan outlet a pipe of the area of the outlet,
see lensith shall be not lees than 20 diameters of the outlet for fans with
nd outlets, or twenty times the avera^ol the breadth and depth for fam
h rectangular outlets. A double Pitot tube designed to indicate the
■sure produced by the impact of the moving air. and the actual pressure
;he moving air shall be inserted in the center of thu pipe at about one-
t its length, with the axis or the tube in the center line dT the pipe. The
ot tube to conform to dimensions shown on drawing, which may be
ained on application to the Bureau of Construction aind Repair. An
ustable throttUng device shall be fitted to the end of the pipe ana adjusted
h the fan running at its designed full speed, with motor fields hot, until
d of water, in inches, shown oy a manometer connected to the pressure
9 of the Pitot tube, is not less than 13.4 times the weight per cubic foot
Jie air in pounds. When this condition is obtained the head of water, in
ties, shown by the manometer connected to the impact side of the Pitot
«, shall not be lees than 17.4 times the weight of the air per cubic foot
^unds. The correct weight of the air in pounds per cubic foot shall be
ained from the tables of the Bureau of. Construction and Repair, which
entered with the barometric pressure and wet and dry bulb temper-
res. The wet and dry bulb thermometer shall be placed near the fan
>t but not so dose to it as to appreciably obstruct the current ot approach-
air. It is the object of this test tp make sure that the fan under test,
»n running at full speed, shall be capable of discharging air through a
e the full sise of the outlet against ajpressure of five pounds per square
t, with a velocity of not less than 2,200 feet per minute at the center of
discharge r4pe. A hook-draft water gaun^ or approved manometer
laratus shall be used in connection with the Fitot tube. For apparatus
record pressure direct a pressure of 5.2 pounds per square foot shall be
Ml as equivalent to one inch of water. No specific requirement as to
delivery with free outlet ia made.
FoTB. — The above-mentioned tables of the weii^t of air under di£Fereat
lospherie conditions will be furnished by the Bureau to fan manu-
iirers upon application.
'ans when tested under the above conditions must deliver their rated
imes at the required pressures and a static pressure in inches fsreater
n 14.74 times the weight of air in pounds per cubic foot, or an impact
Bure greater than 19.14 times the wein^t of air will not be allowed.
difference between the static and impact pressure must never be less
1 four times nor greater than 4.4 times the weight of the air. No means
I be employed to reduce the friction of the inlet during the tests.
I calculating results ctf tests the following approximate formulas will
ised:
r-997
V w
tiis formula assumes that a velocity at the center of the pipe of 2,200
iw minute corresponds to an average velocity over the whole area of
pipe of 2,000 feet per minute.
V " Av
5.2hiAv htAv
H.P. -
33000 6346
r
1198 ELECTRICITY IN THE UNITED STATES NAYY.
when V •- volume in oubio feet per minute.
V "- velocity in feet ])er minute.
Ai -■ impact pressure in inches of water.
As — static pressure in inches of water.
Ai ■*■ At -As -> velocity head in inches of water.
A — area of outlet in square feet.
H.P. '» horse-power delivered by the fan.
W » weight of air in pounds per cubic foot.
NoTB. — Instead of a sin^e Pitot tube a number of tubes, not lev fba
nine or more than thirteen, distributed over the pipe section may be mad i
preferred, by the contractor. In this case the mean statio pressure. ■
inches of water, must not be less than 13.4 times the weif^t per cable M
of the air in pounds, and when this condition is obtained^ the meao impHi
pressure in inches of water shall not be less than 16.72 times the weight ^
air in pounds per cubic foot. It is the object of this test to detenmne tbis
tibe fan will deliver the required volume of air at a mean velocity of 2.0(6
feet per minute over the whole area of the pipe. Similar variatkn ii
pressures to that specified above will also be allowed under these oonditiosi'
The heat run on each motor is to be of eight hours' duration, made vte
driving its fan with free outlet and inlet at the above required full speai
and under such conditions the temperature rises of all parts moat not exeeed
those allowed for continuous-running motors. Also these temperature ne
are not to be exceeded when the fan is run as above at fuU field strength <(
the motor.
Each set is also to be given an endurance test by running for forty-e^
hours continuously at full speed with free inlet and outlet of fan (fortr
hours in addition to the above test of ei^t hours at full speed, the fan to be
started up immediately after taking temperatures at end of ei^t-hour roei,
and during this run absolutely no attention or adjustment is to be gn«
to the motor. At the end of the run the motor must be in operation is*
satisfactory manner and without sparking, blackening, burning, or roop^
ening of the commutator, or the development of high mica^ copper stieknc
to the brushes, or any other latent delects. Any set which fails to ps*
this endurance test on the first trial will be allowed a second trial, utv
overhauling and adjusting, but if i^ fails on the second trial it will be le-
jected.
lieanlta Obt^teed fVom above Sbop
Rated
Sise.
r.p.m.
Ai.
1.36()
A*.
As.
W.
V.
2072
A.
.306
F.
u H.P. from
g Motor.
•
fit.
lit
600
2200
1.041
.309
.0715
634
.135
45.3
BIJ
2500
1140
1.352
1.036
.316
.0726
2076
1.25
2505
1.415
j^afi
39 j;
78J
2500
1140
1 HKi
1.075
.308
.0734
2037
1.25
2546
1.25
.555
443
W
4000
875
1.318
1.014
.304
.0721
2052
2.00
4105
2.08
354
41.
SM
6000
810
1.377
1.062
.315
.0722
2084
2.50
5210
2.97
1.131
38.1
S^
10,000
576
1.268
.971
.297
.0724
2016
5.00
10.080
5.00
2.014
403
su
12.000 525
1.275
.970
.305
.0725
2050
6.00
12,300
6.28
2.47
39.4
^
Electrically-operated water-tight doora are now being InstaDed on nM<^
large ships. Tne requirements of a successful syvtem are that all doo^
can be simultaneously closed from the bridge, that during or aft« vb»
closing any door can be opened by a person desiring to pa» through fron
either side^ and after such passage the door to automati(nUy close itseo-
-. mL^ design in most genwal use is that of the Long- Arm System (^-t <■
VATEB-TI6HT DOOBB. 1199
ngUnd, 0. Th« doon ue mored bj ■ 1 U.F. oomponnd-woiind motor
-■d to tha door plate tbrongh Rpur Bean aod a worm mod rMk. Control
lie door la obuhiad bv ■ imall bufopanMd ODDlroUer, havlu an opsr>
t hondls on MMh (Ida or Ibe bulkhead. ConUal from a dlitano* Ij
dned by an " emaTBaBo* itatkni " located on the bridge whiob oloae* tbe
1 bj meana ot a leeondar; drooit and aolenold*. An ludloalor ti alao
allM at tbe emergeno; ■tation to ehow when eaeb doer eloaei.
laajiteinlBaliawndlaanuiiaatlaally Id Pig. IS. The oontroller oonDeeti
motor dlreflCly to the line, without [be oae of any itartlug teeUtaooa,
the molon are epaelallT deeigoed for thie. When tbe door reaebe*
eh." or the "lower Mmll avilcb," oVtch opeu* the fine afeuit »d
a the door. Theae limit swlt^hm are sctuxted tbTougli a leriea ot
a, epriogi, and loTore. altaabed to tbe driving gearing, lo that a limit
ch 1] opened vbenerer the door plate encounters any great rnelatance.
act the operation of tbe limit svltchi when the door opena or olD«ee,
iiued by the realatauoe to lurther motion, and not by uis poaltlon of
IHUUTOR.
10. 11. Ulacramul
door plate. Thta arrangement prerenta any nbatraoMon from biinilii(
Ihe motor, end at the same time, i( the einergency station aotioil ii on,
door will continue Ita closing motion when tt« obatrnotioB la ift-
', vhlcb, ivben closed, excite aolenoids located In the band oontrollen.
t-baod side of the dlBgrani. are free to rotate on Ihe controllor abstt ;
when the solenoid la excited it nitntes tliem eo that they make eon-
wlth Iheil flugera, and thus prmtuce the same result aa notlnc tha
bo oTerpovered by the hand operation of the controller wben it le
ed to tbe "open" position, Ihua allowing a man at th* door to make
len at any time when the emergeney cloelug ■■ Id aatlon. Upon releaa-
^
i
1300 ELKCTBlClir in THE UNITED STATES KATT.
Ma: >k* kaxUe et tb* band eontrollei It oomet back bj a aprinc to A
•T^- uilttOB, and l( tbs cmsnniicj U itill on, tbadooriteia leda
«ntB. Trfc» in«ih»tito«l eonttruoUon of tba emargenB? ,-•-*' — '- — ' •'-^
)ij ikOTliic » lersr Ibe ountacU tar tbs dlllereiit doon
*ll). In I
ttt.bT«
opermtfls *j
itlufta
UcTAid
r ii powarfnl SDOogb to oat ttarongb htomI locbsa ot eoKl « da
irrioa tba enrrent requlrad for aparaUon ot a TerUoal alidlu '
C » Id. la aboDt aa foilon :
Opemivo :
Buddan throw, ilart X siop.
BuDnlne op S to H) amp.
SoddoD tbroir, atop IB amp.
Cunna :
Soddsn throw, aUrt 10 amp.
BunDlnaduwn StoSaaip.
SuddaD throw, atop .,-,,.-. 11 aatp.
Toltaga la 19S volti.
Tia, l3.I>l>cramotStesrtiii-Oear.
at anT dulmd plaea, moat oOBTwilaitl:
It motor gaared bv inltsble narlns to
otutantlT aiclted trom tba shlp-s malna,
to the brnihaa of tba eonatantlr nmi
< sqaal and ajm metrical rbeoctata, Ibe (
0 tba roddsr p — ' -"
heoiLtata and tba Held of G for
rheoatat on each aide of tba ec
. -Bid of G taking tba plaoe at tba (alTU
battery. Tbla bridge 1* In balaoea, and
STKBBtNO-OBAK. 1201
omot will flow (hrongh tha flald of G vhoDiTBr the two rhaoitaBt trot
cenpj ilmllaT poeltloiu on thxlr rMPMtlTo rhacvUta : but 1( the; du not
wiBpy iliiillar poallloni, Ihen the bridge irlll be out of bKluice uul ouneut
rUl Bow tbroDgh the Held ol O.
The opentiOD li m foUowe : SMrtlns with ererjlhlug coutnl u ihowB
1 the dla[run, If the ■Eeerlng-wheel is turned, moTluB Otn um ot B' k
•rtalu diitaooe, the baluice wQl be dliturbed uKl eurrsDt wllJ How throuh
halMdof O.uoBtBglt CogenenteaoE.M.F.uiilitfttt lb« motor p, whlob
'111 oODtluDe to ruD astll the um of B tau bean moTad > dUtuiae equal to
lie orlgliul moTament moda bt the uxa ot U/, wbeo the bslacee will be
■atored, do eurrent will flow thronch the field ol Q, whleh will then
eralop no B.H.F., uid the motor F will ooiuequaDtlj ilop. The seftrlu
■tweu F ud the wntut arm of B la eo arrwued lh>t the moremaat (3
le aim will be In the proper direotlon >o leatore the balance. The dIrsetlOD
r suirant flow In the field of O, and ooowqaaotlj the polarilj of Q and
Ireotion of rotation of P, wUI depend apon the direction at moTement of
le arm of B'. It la thsi aeon thai iha arm of B Is ilTen no eiaet oopiing
lOtlon ot the arm of B', both tor dlalanse moTed and dlreotiun of rotation.
Innlead of actoallT turning the raddar, the motor P ean be made, If
Mired, to onlj operate the ralTa of a ■taam-ateerlng eugtna ; when tbl( la
)ne tha darlee la sailed a " Talemotor,"
Another method (which haa onl; been appLed for oaa *■ a talemotor) hai
IB flrat moTemant of tha a tec ring-wheel connect the opemtlnj motor
reotl; to the ahlp'a malna, and the motion of the motor caoaea a atep bj
Bp niachanlam to diaeonnect It when it haa moiad the i
atanae proportional to the original moTament of the ateering-wneei. D*na
lUieotiOD and dlaeonneetlon of the operaliug motor are made by a awltcb
the aleerinc-wbeel, the interrapter ot the atep-br-al..
a <qi«rattng motor and the mechanlam Itaelf at the ateering-wheel. The
MShauloal arramsementi are qalte complleated.
ioraral aUpa ol the Hnaaian KsTy h»a been fitted with direct aotlnw
>erin(«eaie bi the Eleotro-Dynaralo Company, of Philadelphia, Fa.,
d work on the abore firat deacribed bridge principle, with (be addition
ft small eielter for the geuarKtor mounted on the Reoerator abaft, and
a Held of thia aiclter la oonnecled with tha bridge rheoataCa, inatead of
( main Benerator Raid luelf. Tba motor of the motor-generator la rated
70 U.P., the generator at EOO amperea and 100 Tolta, and the mdder
tor at EO H.F. : ail being aaallT capable of aUndlng 00% orerioada for
irt perioda of time. The motor-generator rnna at tSO r.p.m. and walriu
MMponnda; (he mddai motor rnoa at WO r.p.m. and wetghaEAnponnda:
acceaaorj appllanoea weigh 1,1100 pounda, making a total weight of
oata made on the Bnaalan Cmisar " Variag" took UO HP. to more the
derfrom hard-*-port to hard-a-atarboard In lOaeeonda. while going at a
i>d of 23 knoti anhonr. For ordinary lEeering at about ISknota, raading*
an ererj Uma tha mdder waa mored gare the following reanlla : —
(J
1202 BLBCTBIGITY IN THE UNITED STATES NAVY.
Readings were taken for every movement ooeurring for a period of |
rudder was never moved more than 16 degrees.
XHTBlilOIt COHBTOinECAVXOir ftYSKKH.
The interior oommunioation system of a ship consists of. as th«
implies, the appliances for transmitting signals of all kinds from one part
ai the ship to another.
Ord«r and Position Indicaton.
Many devices have been tried for the electrical transmianoii of pre-
arranged orders, or the paiition of a moving body, such as a rudder-liaHi;
but tEe most successful and the one generauy installed constats at the re-
ceiving end oi a number of small incandescent lamps, each mounted in a
small, separate, lisht tight cell with a gjass front, ana the whole enclosed is
a suitable case. On the glass front of each li^dit cell is marked an order or
number, or whatever i>articular information the particular deviee is to ia-
dicate. This receiver is connected to the transmitter by a cable having s
separate wire for each lamp, and one wire for a common return. The tnu**
mitter consists of a switching device, by means of wMch any lamp or lamfa
in the receiver may be lighted, the current being taken from tne UgfatiBi
mains. As many receivers as desired can be operated from one tranamitts,
the receivers being connected in parallel.
Aolaa Aagrle Ksdicaior*
When the above-described device is used to indicate in different parti if
the ship the angle that the helm is turned, the transmitter switch oonsitf
of an arm, as shown in diagram (Fig. 14) fastened to the rudder stock, and
moving over a series of contact pieces arranged in an arc in the same rrt^nt,mr
as an ordinary field rheostat. Each of the contact pieces is conneeted
through one wire of an interior communication cable to one side of one cf
the receiver lamps, which lamp has marked on its front the number d
degrees that the given contact is situated from the center line of the ship;
the other side of the lamp is connected to the common return wire, i^m
goes to the source of current and then to the contact arm. As the rodder
turns, the contact arm makes connection with the different contact pieon,
and as it touches each piece the corresponding lamp in the receiver lighti
up and indicates its position within the limits shown: when it is just mid-
way between any two pieces it will touch both and light both corresponding
lamps, which doubles the closeness with which the position is indicated.
As many receiverB can be connected on as desired, aU being operated io
parallel.
When used for en^ne order telemphs the contact arm is mounted in s
metal case and operated by a hand lever of the same construction as tke
hand lever of an ordinary mechanical ship's engine telegraph, as shown is
Fig. 15. The case contains indicator lamps in parallel with the lamps cf
the receiver at the engine room, so that the operator on the bridge hsB
visual evidence of the order sent. A small magneto is geared to the tiaa»>
mitter handle, and rings a bell at the receiver whenever the handle is movsd,
thus calling attention to the change of order.
Battle Order Isdicaiors.
The receiving indicators are of the same construction as above described
for the Helm indieators. but the transmitter consists of singjle-pole snap
switches, connected up exactly like the lamps of the indicator, so that nr
turning the proper switches any desired number of lamps can be Mgb**«\
INTXBIOB COMMDMICATION 8YSTKH.
i
I
i
*l of BBorw ■ny d«iini] order eu b« markad in front of uiT Immp. Sev-
■I indiostfxa. looated id dWennt parti of the ehip. *t« uninlly worked by
"■" " '''"~r, oil bfliBff AOniiBotA] In pvrAllei.
ih mnUiiui ttM irananit|«r owitches also ooDlaioa an llidlca-
■e bcinc indioaMd on Ibt (yiton.
V
1204 EI.ECI&I01TY IN THB UHITIID STATES NATT.
Fra. U. DUgism ot Engioe Tolicnph.
IniteaS at hsTlng dUTsrent . . _
naeDtlngUM rkonln jarda In
A nnge iDdlealar and a battle ordar :
gMher M dealrvd staUou, tbna (having
battle order [ndieatoTB, ttXMpllM
bridge the dlrestlon
- ' '--nidOTliod, Tneonemo
>llKeirK,noiuitMl*<
ihatt 9, and meehlug vuh a pinion t>, wbt
in arm A. The arm A li alolted and mon
en S la routing, A will be (omed lo oae all
le dlnnMon oTrotatlon of 8. natll It hito oi
Lortit vUlBiakaaiH
Toeht .
(eTeral applUnaaa hkrebeen derlaed.
In Fig. Id, and aonglits al I '
trl-MAj upon the prapellei
the other, depending upon
■ top B, and (rill then remain againn toe atop
from tbe eeeentrlo aotlan of B ; an eaeh np m_ .
— <Ui slip 0 OI 0", depending opoB trhloh iCda U la tu
INTBRIOB COHMUNIOATIOH STBTBX. 1306
Ibe rcoaiTar soiuUlii of two plrotad polnton, aanB«Uil <■ ihowB t« two
MtronuftiMa KDd markad " Astsm" uid ■■ Afasad."
PruED tha ooDDHtlon* abown, It Is Mea thAt mt oAch rotation of the pciH
ll«r ituft IbapoiDtsr eorraapondluc to tbo dlnetlon of rolBUcm will nuke
nanmant, uid mt Iha ume tlm« Ui« mafixt armature will maka a plalnlr
dIbU oUek, thoa Indloatliic botb rtiaallf and andlbl)' tkft rotatloD. Tb*
i
1206 ELECTRICITY IN THE UIFITED STATES NAVT.
other iwlDt«r oomflponding to the dlnotion in the oppoAitfl rotatioB *rit
— _?__ — ^jj^^ ^i^j prevanta irear- E ifl m Imrfe muJupie wata
ropaUer nhift S. D ii a trnnii whul on tha hukU iWl
id inakn'cxmtut actnMTwo of thflnds oa ahon. C
•vti B Klong its shafh and bokb B in U» i«itiai] ibmi
lulloo al F. Cor ahwd ratation C ahitu B to the n#(
Fki. it. IKaflnm of CoiuiMtloiu of TmumltMr for Revolulioa IiKficaM-
eonlaot ia made between the realer and ncbl-tttcd leads, fa
' with faaC ninninl propdtar ehafts the ceannc imtio «( E
rbine vhhIb with faaC ninninl propdlor ehalts
d D it proparlioned no (hat ODly one indicator is
Od the latest TeMekseentisl etatknls provided to which eBchnttadinellT
conneoted. Fia. 18 ii a diuram of the ByeteiD >a turniahed by tba Wretaa
Elactrlc Oo. The oaitral hoani )■ known ai the conlkas ami phvlw
type. Ita nuin featur* osnaiati in havlnf the oonnectioD cirniita •rmatv'
In a aeriea of horiiontal biu-hare wlich are srnased vcrtlakUy by tbe talU«
wirea of each ttation. ao tbat by siiltiiw an ordiDary aprint lerer kiv ai
each interseetioB any dwiml ooiibiiutiOD of a>D»etkau can be mada
IIhuUI)' the board is arranged fur fifty stations and fire oooiMctioB
■o that five scoirate convenation* between any five pain -' - ■
ma/ be carried on at the same time; also for isauins nne
deeinid number n! telephonn may be eonnectdl tqaotber. .» »_v_-
ahnwi only two oonnectinn circuits and two stations. &it it can be bxmM
as dnired in cither way. •
The operalion is aa followst
Three wires mn In pach station, two for taldnc and one for riaef-
When the rereivsr ia taken olT the hook, eurrsnt rrom the talkinK tiatlat
flows (hrouah the lalkinx line wircx and diapta^ the line ei(iua: Vks
the operator throws one of the oonneotion keys of the sbUIh set tha Ii*
Bignal ia cut out and the talking wirfs oonneatad direc* to the borisc^
eonnection bus which ia pennBHently conoeoted to the t^kiiw nmot
supply. Throwing the Mnoeciion km of the pMty to ha ealled, wbid'
Ringing is acHimpi iabed by a separalfl rlngiUR key lor Mch sM. taiaia
current from a Bcparale ringing battery and operalinj; through th« comiacs
riDgins wire and the left-hand talkinit vin aa abawn.
Each boriaonla] connection bus has a olearing-out sigttal whicft is dia-
plared when eumait it flowinc from tlie talkuw supply. Whan toik
INTSRIOB COMMUNICATION SYSTEM. 1207
rcu/t. Circuit,
W" 20"
I . I [ . 'II ^'^•^^"'"^ A
(
WTSSTHfl/. KKTScrmZ
Fla. 18. Dbwmn of WcaWrn Electiic General Telephone Syatcm.
1208 ELECTRICITY IK THE UNITED STATES NAVT.
parties haaff up th« reoeiren the flow of the talkinc eorrent rrBirm and thr
signal falls back.
, A nicht bell is provided which is operated by a relay when any line
IS displayed, also when any oleariiiK<out signal falls baiok and the
qwnding connection keys are not opened.
Gross-talk is prevented by ohoke coils (not shown on diacnoa)
IkLSn'JIf^d
7ki.^mz
w ^ TilLMMV CnMOT A^Mltltf
Fio. 10. Diagram of Holtaer-Cabot Qenetel Telephone Syateai.
in each side of the horisontal connection busses just after their fonnerti*
to the talking current supply. Both talking and ringing eurrents ffc
supplied either from batteries or motor generators taking power from tks
ship's generating plant, thus giving a reserve.
Both watei^tignt and non-water-tight telephones are used. The bob-
water-tight are of the ordinarv wood case wall pattern, while the wmteMig^
sets have the mechanism enclosed in a brass box with the cover havinf *
rubber gasket and heavy clamps.
Figure 19 shows the design made by the Holtaer-Cabot Go. Thegeosnl
s<^eme of operation is the same as above deseribed, the main dunereaos
IMTEBIOR COMHUNICATIDK STSTEU. 1209
HI thai tli< opentar'i ut is hmndlcd by ft wpante uMitional raw of
•ainiUad of beiac tmMd simplv u ■ itetion.
Isun 20 nbawa tha daato made by Ch&rln Corry A Bon. It u |«wr-
' vmilii to the above lyitsmi, but lua a Mparate battuy tor eadi
daa: olreuit Iiutcad of luins tailing curreDt from a oomnujD bus 4up-
■d^ d}iiamo ourrent. Also oacb talkinc stnuit oonaiaU <d tno Mta <d
iDlal buMM. and tha ixiDn«tion keys may be thrown cdtber way to
It flow tbroii^ tbe eontanta andliutnnncntii. Euh sa
ia ao cmupad that one lever opentsi them all.
Um »bovit tdephona dlagrBina the following notstioD i> und:
1210 BLIOTKICITV IH TUB UITITKD STATES SAVT.
at CooDMtioiu of EI«trio WliiaUa.
Tbe Gn aluta Byitsn oan
And bfsvt haviQE 4 h'lgb t«inpfintturfl ooeffidont of flKpu
oos tad Ins so Uut (ba totuonai «SMt produnad by ■
1
MISCELLANEOUS. 1211
08 a slicht displaMment of the free end, thus clonus the drouit and
ftting- the corresponding annunciator drop. The working parts are
3eed in a heavy brass case.
lal bunker and storeroom thermostats are set for 200 degrees Fahrenheit,
those in magasines at 100.
IPFator-tlg'lit Hoot Alanna.
» give a general signal for the dosing of all water-tight doors, a system
arm whistles is used. The whistle consists of a solenoid which pulls
ore down into an air chamber, and thus forces the air out throUjKh a
I shriU whistley The core is restored by spiral springs. All whistles
lonnected in parallel, and are operated by a make ana break mechan-
whi(jh by the pulling of a lever will interrupt the circuit oontinuously
,bout,30 seconds, each interruption giving a blast froc^ each whistle,
snt from the lightning mains is used.
le construction is shown in Fig. 21. The clockworks for operating the
ict maker is constructed so that by rotating an operating lever it is
id up, and upon releasing the lever it vibrates the oontaot wnUe running
1, thus giving periodicaTsignals.
the latest design the whistle is inverted and pulled up against gndvity,
dispensing with the restoring springs.
Call ]|«1U.
. elaborate Myntem of call bells, annunciators, electro-meohanieal signal
I, etc., is installed on all large ships. The main difference from ordi-
oommercial work is that all appliances are made water-tight.
m»cKi:.i.Aifsoij».
9 following is a brief outline of the principles employed in the ixtttru-
designed Dy Lieutenant Bradley Fiske of the United States Kavy.
Fig. 22 let A represent the target and BC a known base. Then
ACiBC: : sin ABC : sin BAC.
sin ABC
AC '^ BC X
sin BAC
i ang|e ABC can be readily measured. The angle BAC « DBE, the
'>E being parallel to AC.
I Fiske rauA^finder measures the angle DBB by the use of the Wheat*
bridge, as follows:
tpose the two semi-circles in Fig. 22 replaced by two metallic arcs (Fig.
At the center of each of these arcs is pivoted a telescope, the pivot ca
is oonneoted to a batl^Bcy B, ..Xiie tMespopes are in electrical contact
he arcs. These metallic arcs are connected at their extremities with
anometer, e, th« whole, forming a Wheatstone bridge, whose arms are
sn the tdesoopes are pointed at the object A, it is evident that the
if the bridge are unequal, and hence do not balance; and this fact is
ted by the deJSection <^ the needle of the galvanometer. The arc FD
ad. By swinging the telescope at F around till the needle of the
IOmeter indicates sero, the b^dge balances, the telescope beixig
d to the one at C, and the arc or, angle DF — FE is equal to the
at A, From this the distance AC can be calculated, or read off
y on a properly constructed scale.
endly, m using the instrument, the telescopes are mounted at a
DO from the battery, whjere the view is uninterrupted, while the gal-
\etw. in at the gun. The observers keep the telescopes constantly
1212 BLBCTBICITY IN THB UNITKD STATKS NAVT.
dirMtad on the target, and the maa at the gun halanoee the bridce hr i
trodooins * variable rasistanoe into the oiiouit till the needle ataodi
Fio. 22.
Fi0.2a.
aero. Tliis variable resistanoe is graduated so as to indioate the ruM
eorresponding to the resistanoe introduoed. This instrument is not now weo.
Large jnins are arrangsd to use both peroussioa and eleetcie primen for
firing. The electric primer is of the same external shape as the
primers, and is exploded by a fine platinimi wire, heated by ourreot from
the cells of a dry battery mounted near the gun. A ground return is ussd
and a safety switch is fastened to the breech plug, so that the etreoit esa-
not be completed until the breech plug is closed. A push-button Is used to
complete the circuit and fire the gun.
The same primer is also used for igniting the charge of powder to eipd
torpedoes from their directing tubes. Fig. 24 shows a section ni the prinNr
ano diagram of connections lor both torpedo and gun filing. In torpsifo
firing the opening of the sluice gate, which permits the torpedo to be <&»•
c^rged from the tube, closes the circuit and operates the sisnal lights at
the tube and firing key. This also acts as a safety device by ptwvaitiBf
the primer being fiied baore the gate is opened.
An instrument called the "Weaver Speed Recorder" is ^ ^. _
for measuring the speed of ships when run on the measured mile, and irfuk
being launched; also to measure the acceleration of turrets dnuing (art-
It consists essentially of a clockworks, which drives a paper faipe ovws
set of five pens operated by deotromagnets, so that when any magsitii
excited it ^lls its pen against the moving paper tape, and makes a dot
thereon. The connecting levers between the magnet and pen are anangv
something like a piano finger action, so that no matter how long the ma|^
is kept excited, the pen will only make a quick, short dot. All pens ars
located side by side in the same line, so that if they wne all operated it
the same instant, the result would be a line of dots across the tape.
When used for measuring mile runs, one pen is connected to a make sod
break chronometer, so that it makes a dot on the tape every aooond; sa>
MISCELLAintOUS.
1213
1
•fthar ptn is eonneoted to a hand push-button, to that a dot oan be made at
Um start and finish of the run, and at as many inteimediate points as d»>
rffed; the other three pens are oonneeted to oontact maken on the shafts
of the main eonnes. so that a dot is made for eveiy revolution cf the en-
line. (If the ship has twin serews, of oourse only two of the remalninc
pens ars ussd ana if sinsle screw, only one.)
It is thus seen that by oountins the number of second dots between the
itart and finish dots, the length of time to make the ran is given, and by
Nsuunoif
9ECTI0N OP PRlMERt
ILUICC GATE
f fICUIT CLOSCR
INOICATDII
LAI4F
i^
fllftNaKCY
s
PILOT LAMK
AT TUBE
W9ISTANCC
r-^iMoi
CONNECTIONS FOR TORPEDO TUBE riRING.
nmm key
BATTERY
PRIMER
«^ SAFETY
dWiTCH
Q ^0
Fio. 24. Connections for Torpedo and Oun Firing.
r
1214 BLEGTBICIT7 IK THE UNITED STATES NAVY.
oouDtiii|s the number of revolution doto in any desired spftee, the speed rf
the engine is given. Fraotional seoonda or revolutions can easily be sr *' '
. When used to obtain Launohing curves, a long steel wire wound on a
has one end attached to the ship, and a contact maker is fastened to i
drum. As the ship slides out the drum is revolved and dote made on
tape at each revolution; knowing the diameter of the drum, the speec
any instflcnt is f6und by comparison of the revolution dote with the sew.—. ^
dots> The band-iMish is usea to mark the starts finish, instant of pivofwfc i
and any other desired matters. i
When used for acceleration runs on turrets, the same procedure as
launching curves is followed, except the contact maker is attached to
rotating part oi the turret meohanism.
J
1
RB80NANCB.
RjiTisBD BT Lamar Lyndon.
F in an dtemating eurrent drouit, an indaotence be inaerted, the aelf*
ueed E.M.F. will oombine with the impreased E.M.F. and the reaultant
the two will be the active E.MJB*. wluch cauaea current flow. The cur-
t will alwaya be exactly in phaae with and proportional to the renUtant
4.F.
The inductive E.M.F. is 90 degrees, or one-fourth of a cycle, behind the
r«it, and, therefore, behind the reaultant E.M.F. which is in phaae with
current. The iJgebraio aum of the inatantaneoua valuea of the reault-
and inductive ELMJ.'e wiU ghre the corresponding valuea of the im-
aaed ELM^F.
Ig. 1 ahowa thia aummation. v.v,v,v. ia the reaultant E.M.F. re-
ned to aend current i,i,t,i, which is in phaae therewith, through a given
atanoe. LfL^L.L^ is the curve of inductance E.M.F.. one-quarter
iod or 90 degreea behind the eurrent and the reaultant E.M.F. Combin-
the ordinatea of v,v,v,«, and L,L,L,L, the curve s.ej0.a, ia produced,
I repreaenta in phaae and nmgnitude the impreaaed E.F.M. required to
i eurrent i,i,tti« through the resistance and overoome the counter E.M.F.
he inductance. As may be seen, it ia aomewhat in advance of the
Jtant E.M.F. and, therefore, of the current. Also it is higher than the
iltant E.M.F. by an amount which at each instant ia equal to the coim*
EI.M.F. of the inductance.
Fio. 1.
» oondenaer or capacity be included in a circuit, and an alternating
nt be sent into it, flow will take plaoe in the condenser, the eurrent
inir and oharging it. Aa the amount of electricity atorad Inereaaea,
STIl.F. of the condenaer inereaaea also until the impreaaed and con-
a* £LM.F.'s are equal. The condenser E.M.F. being a counter pressure,
Dt flow oeasea when the two E.M.F/S balance. The current being
at this point, and the condenser E.M.F. a maximum, it may be aeen
the oondenaer E.M.F. ia one-quarter period or 90 degreea in advanee
9 ourrent, ana, therefore, of the resultant E,M.F.
Piff. 2, V,V.K,K, ia the reaultant E.M.F. made up of the two E.M.F.'a
r on the circuit, ititi,if the current, c,e,e,e, the condenaer E.M.F.,
1216
1216
RESONANCB.
which is 90 demes ahMd of %,%,%,%. GomUnixiff V,V,V,y, and
impressed E.M^. curve «,«.«!«» is produced, whioh is
curreat and resultant E.M.F., and behind the condense
the impressed EI.M.F. is ip'cater than the resultant E.M.F.
From the foregoing it is evident that if either a capafdtv or ind
be inserted in an alternating current circuit, the phase of thie
As
respect to the impressed EIM.F. will chanM, and the current flow be i^
duoed. Since the one sets up an E.M.F. 90 degrees in advanoe of tbs cn^
rent Sow and the other a pressure 90dcKreeB behind it, the two effects tend to
neutralise each other when connected in series, and when thev are jurt
equal, no E.M.F. other than the impressed is left to act on the cira^
the resultant and impressed E.M.F.'s are identical, and there is no phase di»>
placement. This condition is called nmmanee and is shown m Fig. Si
Fm. 3.
The curves L,L,L,L, and e,e*c,e* are equal and opposite at every
and neutralise, feaving the impressed E.M.F. as the only one
circuit.
The conditions lor resonance then are, that with a given
current the capacity and inductance be so related that the counter
set up by them are equal, or it may be stated another way. If in
Dating ourrent circuit an inductance and a capacity be oonneeied
either of which, if inserted in the circuit alone, reduoes the ewrent
same amount, resonance occurs and the current flow is not changed
presence of the two in 9€ri99»
•ctii«cate
frequency ssd
m
flowtbi
hytte
^
BESONANCB. 1217
Tlie fommk for altcmalinc enmni flow in % oireait of>nfiBiiwg vniatanM,
induoUnoe and oi^Micity ia
' -
V*+(^-i^)*
in whieh E = E.M.F. (Impressed rolts),
/ = Current in nmperes,
J? = Besistence In ohms,
L = Indnotenoe in lienrysv
J=i Capacity in farads,
w = 2 i^T = 0'28 X frequency in cycles per second.
If tlie capacity and inductance effects neutrallae,
Im=z--jt and JW — j^ = «, (9
md formula (1) becomes
/=--==-• (8)
rhich is simply Ohm's law, showing that the current flow is opposed only
»y the resistance.
The larad is too large a unit for practical work, cMMurfties seldom bdng
acre than a few micro-farads (or one miUionih of a feuwd). If / be
B mioro4iarads and called J«, then for resonance
, 1,000,000
too « = 2^.
,000,000
~2ir r LJm
(^
<n
bieh is the frequency at which resonance will occur for a capacity Jm
id an inductance L, Since the opposing: E.M.F. of the inductance ia-
■ that of "
with increase of frequency, and that of the coskdenser d< _
th a given inductance and capacity there is only one frequency at wliloli
ey will neutmiise and resonance result, and if this frequeney be changed,
B EJflaF. of one will increase while that of the other will decrease, thus
Btrojdng the balance between the two.
Am ua eocampie, assume a drouit having an inductance of 0.44 henry,
d a eapacity of 16 micro-farads. For resonance the frequency must be
Phe oppoBing inductance and capacity E.M.F.'s often set up local poten-
\m very greatly in excess of the impressed*
ince the voltage required at the terminals of an Inductance to force a
s*
en enrrent through it = JS| = mLI, and for resonance, ^=^t (be roltage
ibe Inductance
1218
RESONANCE.
Alflo the Tolta^e required to tend a glTen eurrent throngb «
— » or
/ X 1,000,000 _Xx 1,000,000 m
AMmne the olronlt of 0.44 henry 16 micro-fanuls and 6 ohma.
/=:00o7olee,
ImproMed E. M. F. = 250 Tolte,
the Toltage at the terminals of the indnctanoe,
while the Tolts at the oondenser terminals
_ _»021iOWjOOO_ _ ,
which is the same as the voltage at the terminals of the Indnotanoe.
Fig. 4 shows the diacram oi such a eirouit and indieates the potaBtak
between tlie different terminals.
RM OHMS
(^AAA
nnnnni
HSt9»V0L
sImr
m
•0 AMPCKS
Pig. 4.
From the foreffoinc It is obvious that the smaller the resisCaaes. tkt
greater will be the local voltages set up by the capacity and indiictaaea
For instance, if in the previous eacample the resistance were S} <A0i
instead of 5 ohms, the current flow would be 100 amperes and the poAeo-
<tlal at the terminals of the inductance and of the oondenser wDud be
16.580 volts, the impressed E.M.F. being only 260 volts as belbra.
In practice the capacities and induetaaees are seldom ao related si ta
• allow complete resonance to occur at commercial frequenoiee, tlwM^ ufan*
ever a civMciiy and inductance are in series the partial nevtiafiMO*
which takes place is liable to increase the E.M.F. kxaily to a hig^ ^nki
than that of the impressed.
All the foregoing is based on an Impressed E.MJP., which is a pore waf
function.
In practice, however, the E.M.F. wave differs more or less froo d*
form, and may be considered as the resultant of several nure sine «sitf
of varying amplitudes and frequencies. Those waves whioi have a U^
or "uDper harmonics" may have a frequency at which resonance e9i^
suit. From equations JQ and (7) it is clear that, with a given i wj^iy*
in circuit, the rise in E.M.F. due to resonance is proportional to tfes B^
pressed B.M.F., and since the voltage of the ujver harmonics if laowf
small, the rise in E.M.F. cannot be great.
When resonance occurs with one of the upper harmonies, the wave Ibis
of the current becomes greatly distorted, because while the ether eoHPS*
nent waves must force the current sgainst both the resistance and tss
reactanoe (i.e., inductance and capacity E.M.F.'s), this partMsr «•«
^
BKSOKANCE.
1219
only to oTaroomo the ohmite reristanoe and, thereCore, mdcU a graaUr
■«nt through the oireuit in proportion to its Toltage than do the other
[.F. waves.
11 these considerations apply only to eireuits in which tbe induetaace,
ftance and cmMurity are in series. If the inductanoe and capacity be
neeted in parallel, as shown in Fig. 5, there can be no rise of voltage
ve the impressed even if the two be in resonance, but currents greater
1 those supplied by the source of impressed E.M.F. may snige Imok
forth through the local ctreuit, joining the condenser and the induct-
B, and, unless the resistance be high, the current sent through the main
5.fl4AMPS.
Fio. 5.
uit will be greatly reduced: indeed, if the resistance were leio, the alter-
>r could not send any current whatever through the circuit, for at every
M of the impressed E.M.F. there would be an equal and opposite E.M.F.
jmt from the condenser or inductance, and the resultant or active E.M.F.
}mes aero. This condition is represented in Fis. 6 in which the curves
resents the impressed E.M.F. c is the curve Oi condenser emrrtrUt and
f cunnsnt in the inductance. The condenser current is 90^ in advance
;he impressed E.BI.F. while the inductance current is 90^ behind it.
Fio. 6.
e being no resistance in the circuit. The sum of the two currents then
ways equal to sero. as may be seen.
lie physical conception of this condition is that of current flowing into
oondenaer, ehaxtdng it, while the previous stored energy in the induct-
> discharges. This discharge sets up an E.M.F. opposing the impressed
JP., and also furnishes the current supply to diar|(e the condenser,
reversal of the impressed E.M.F. the condenser disehuges into the
otaooe, at the same time setting v^ a counter £Jf .F. to oppose the
of onrrent from the line.
HE80KANCE.
dlipluB the phan relBtiou of th«
flow In thft main oireuit, but this w
Aa Ml Bctual IBM, consldar the bi
A hu %a indiiotaaiw of .03 beory i
m, upMlt)' of Wmlenhfkndi, mndt
tjtltm par HHiul, mod tiiipr«Med KM.r.
Impeduioe of branch A = VCS)' + (S-W x
Currant through bttuioh ^ = ^ = 7^ «ii
Twi. »ngleoI i^g — '-^X "'"^■'" = ajM
oorrMpondlnB to nn nngls atttf — W.
= v'w+(j3
Tu. MIglSDf lead =
Combining thsH two ourrent* in thdr mpper phu> nlUioD. ttam''
tlw ourreot throuch the suia dreuit. Thb am b«t b« don* OwU-
OKlly after the uninl muiner ot combinint EJIJ.'C
J, current* Teo«ori«lly.
ft In Eic. 7 let the boriioBtal hoe OB reprmnt Ihi M-
/ I preaed E.M.F, ud be the refertnee lina. FnnOMB
/ \ uuleof 68° - IS* upvMiJi by off 7.12 ampsa u> i«
/ 1 nuUble sole. At nn ugle of 76° - M^dom"*
/ '.>!■)' of 3.0S amperee. CompleM the pumIMc«nii>. •>
./ j iiidt(«ted by the dotted UtH*. Thediaconft]fnMnO|i<^
// /7 the value of the riaultant eurmt (brouch tbt OM |
// „// dreuit ai 6.34 amiMTea. and dwwaaln that it iibdk^
*/ JR' / the impreiHd HsTf. by «° - 39'. Thu. H wH^
*>7 j>X ' MW. lA Ina current than would flow through thi (0^
/ *Y ' ^y brand) A if the parallel branch 8 war* liB*
/ /N / romoTed.
A(f Hifi.- H the roMitanM E.M.F.'i have the eaiM rah**
A oapacity belns .00006 farad (- GO miero-UrvIa). <"
ti — E iDductanoB wBl bo equa] lo .0808 henry, Aaeonw *[
V<25)»+<31.83)' -40.47 and eomnt- i^''*
ampena. Tan. of the an(1a of la( — —^ - ■ ■'"'
oorreapondlng to £1° - 40*. Combhiitic Ui« nM
with the 8.0B ampera at an angle of lead of 7S* - 64* la FIc 8. (ba i^>-
RESONANCE.
1221
onmot is 3.49 amperei, and has an angle of lead — 4^
rant 18 lefle than that in braneh B alone.
iV>r the currenta in two parallel branches
balance each other, so that the resultant
rent thronirh the mnin eirouit is brought
phase with the impressed E.M.F., the
>wiDg condition must exist.
Iw amperss flow through one braneh,
Itiplied oy the sine of the angle of lead or
ox the current (referred to the impressed
LF.), must be equal to the amperes through
other branch multipUed by the sin at
uigle of lag or lead, llbat is:
X sin ^=/. X sin f , in which /, and /,
the currents through the two branches,
angle of lag of /, and it is an^e of lead
••
'^in branch B of two parallel elronita the
Impressed E.M.F. =: iP,
Capacity = J,
Besistance = A,
theimpedanee= y iP+ (rrr) *
dng 6.28 X frequenoy.
B
The onrrent =:
- 94'. This
Mi^r
Tan of the angle of lead = -^,
I which the angle and its sine are found. In branch A, either the resist-
> or reactance must be known. Calling I^ the current and ^ the angle
»ad in branch B^ Ix the current in branch A, and ^ its »ngle of lag,
/, sin 4r = /| sin ^,
Tan4=— jj^i— =:^. («)
y/l — sin« 4 Bi
re J2| is the known or assumed resistance in branch A,
JZji X sin> 4 = 2A*2 (1 — sln> ^),
sln^=y.
Ii sin ^ =
Bt^-^L^
B
\/B^^-\-V^
BZm
= /, Sin ^.
ng /, sin ^ = #, and solTing,
^,
(•)
m
(11)
len i2,s is equal to or greater than —^ the quantity under the radical
nee saro or negatlTe. and there Is no reactance which will -compensate
&e effect of that In the other branch, the reeistance being too high.
1222 RESONANCE.
The sign before the radical being either plug or miaiis, there mre
of reactance with a given resistance which will eompeiiMUe (If iK^ be noi toe
great) . The lesser reactance will, of oourse, permit the greater enrrent flew,
both through branch A and the niain olronit.
As an example, assnme a resistance of 8 ohms, a eondeneer eaiwdty cC
60 micro-farads in branch B ; also a freqoenov of 100 cycles per seeoaA,'fae"
{iressed E.M.F. = 100 rolts, and a resistance of 10 ohms in braaoh A» Whsl
ndnctance must be inserted in branch A to compensate for the reaetaiiee ia
branch^? Amperes through branch if == /. = 3.06. Aiurle of l««d = 18*
6i" = i^. Sin ^ = .96887.
/,sin^ = 8.06x .90087 = 2.9681 = 9.
Substituting in formula (11)
J. _ 100
2 X 24W81
L« = 16.902 ± 13.614= {gjgj.
Tan, = ^.
8 288
Taking the first value. Tan ^ = -^g- = . 3288,
corresponding to an angle of 18^ — 12^',
sin ^ = .31233.
Current through .^ = - — = ii.47 Mnp^F— .
V(10)> + (3.288)»
/sin ^ = 9.47 X Jn23 = %MSt,
which (within the limits of tabulated values of functions of angles) dieeks
with the value of / sin ^.
^V*X(2JI681)t ^ '
Flo. 9.
The resultant current in the main circuit is found graphicallv — shown br
full lines in Fig. 9 — to be 9.76 amperes, and in phase with the impraiced
E.M.F.
If the greater value of £m be taken,
Tan 4 = ?^^= 8.0616 = n<>-fiO",
sin ^ = 0J)6016.
Current through branch A = — _ = 8.12 amperes.
VCIO)* + 0*0^1^
/, sin ^ = 3.12 X 0.06016 = 2.964, which checks with /, sin ^ (within limits of
tables of functions of angles).
^
RESONANCE. 1223
Basnltuit omrent ii found mphloally, as shown by dott«d lines in F!g. 9,
to be 1.72 amperes, and Is in phase with the impressed E.M.F.
From the foresting equations it can be seen that if Xm be known and R^
i the quantity to be determined,
'.=^/^f^y
(12)
If JL and L of braneh A, and J^ of branch B are known, the capacity re-
inirea in branch B is f otma from the formula,
•/» S z=z* (13)
II which H a /i sin ^.
If Bi, X, and Jm be known,
If /be taken in farads, formiil* 14 becomes,
THE ELBCTRIC AUTOMOBILE.
Rbvisbd BT C. J. SniNCBB.
Elbctbio automobiles are desirable for deUyery service where the
traveled per day is from five to thirty miles. Where the distance tnti
day is less than five miles the service can be performed at least ooet intk
horse-drawn vehicles. Where the distanoe traveled per day is sreals
than thirty miles, gasolene can give better results than those operated nlnftri
caUy.
llie above statements should be taken as applying to gsnecal oolKfitioaa
Where the conditions are in any way special, costs for operation by eadk
of the three sjfstems should be computed. Owing to the ooet d m hoot
and wagon being less than that of an automobile, a certain anKmnt d
work must be performed each day before the efficiency of the autonwIiSe
becomes apparent. The actual cost for gssolene usually is found gjieinr
than the cost for diarging storage batteries of automobiles transporliac
equal loads to equal distances within the limits above givm, aiul toe eon
for repairs to the mechanical equipment aveiages higher for the
than tor the electric machine. Certain limits to daily travel will
be found ^ere each type of transportation is cheapest.
Ilcelatence ]>«• t« C^r»Tttj, mmA P«irer Se^v
W. WORBT BbAUMONT.
The horse-power reauired to overcome weijBht. speed, road .
gravity resistance, ana efficiency of transmission between armature akmh
and iMd wheel, may be found as follows:
Let R "■ the resistance to traction of the vehicle on the road in poandw
per ton.
O 'm the resistance due to gravity in pounds per* ton.
W — total weight on the wheels in tons.
V •" speed in feet per minute.
V » speed in miles per hour.
S » mechanical effidenoy of transmission from armature sfaalt to mad.
P •« brake horsei;>ower.
s -■ efficiency of motor.
p «i watts supplied to motor.
p « <n + G)WV .. ^ PB d76 ^^
^ 33.000 JS *^' (R + 0)IF' ^*
(^R-\-0)Wv . Pg375 ^
(fi + <?)-^^' (3) p-74e^. (7)
1? (R + G) vW f..
For a more detailed discussion of the mechanics of traction see Blaeirk
Traction,
1224
TIRES.
1225
R«aUt«mce to Vractioa oa Coaii
W. WORBY BbaUMONT.
Road Surface Material.
sphalt
^ood, hard
" soft
(acadam, very hard and amooth . . .
'* traffic rolled, wet
" steam rolled, new and muddy
** new, flat spread
rarel
ranite tramway
■on plate tramway
Resietance in Lbs. per Ton.
On
On
Iron-tired
Solid Rubber
Wheels.
Tires.
22 to 28
35
to 40
22 '* 26
iO
•• 45
80 " 38
40 *' 45
35
« 40
45 *' 52
52 ** 58
58 ** 02
95 " 105
100 *' 140
12.6 •• 15
10 " 12
In most cases these resistances increase slowly at hicher speeds, and it
net also be noted that the resistance on bad, soft, and gntvel roads will
'obably be gnaUr with propdljng wheels tkum with most hauled wheeb.
oat ox the figures relate to road resistance at walking or slow trotting
Solid rubber tires have a higher reslstanoe than steel tires on asphalt
ads and have less resiatanee on macadam and other roads. The per-
stly smooth surface of the asphalt produces a drag on the rubber iires,
us increasing their resistance. Pneumatic tires are best adapted to
ads with slimt inequalitfes, and for pleasure can run at high speeds.
»r both solid and pneumatic tires, the draw-bar puU reouired to over-
me the rolling resistance depends on the speed. This subieet has been
restigated by Mr. Alex Churchward, and the results of his tests* are
irinted below:
Material of Road.
Grade.
phalt
Level
«adaxn
1.1%
cadam
Level
!gium blook ....
9.5%
>halt
4.7%
M>^*^TW| ^
3.75%
»halt and brick . .
3.125%
halt
2.25%
Draw-Bar
Miles
^.•'
Pull in Lbs.
per Hour.
40
12
Solid
50
12
Pneumatio
48
11
Solid
65
10.6
Pneumatio
41
12
Solid
49
12
Pneumatio
250
5
SoUd
270
132
5
7
Soli<i
150
7
Pneumatic
114
8
Solid
128
8
Pneumatio
95
8.5
Solid
119
8.5
Pneumatic
85
8.8
Solid
103
8.8
Pneumatic
* See Th€ Commercial Vehicle, April, 1906.
1226 THE ELECTRIC AUTOMOBILE.
Tbs above fisurn iu« sveniM of rcadinci Ulcm for ■eymtsi
bait ETCatly affect* Uie (
diScraooe of 40 per cent wu found ia the power r«qiiii*i] E
of 119 poundj
muddy rt»di
^«ed In lUles pe^ Hooi
Rnulti of Ueti lor the trulive effort »t WTnl ipeeda u« ibown hr tkl
curves in Fir, 1. It will be notioed that the draw-bar pull dimiiuAaa M
the ipeMi ia rttlueed, toa miDimuDi. and InBreaMa a> the ipeHl ia atiU tutbc
BATTERIES.
1227
le present practice is to install one motor on all, except the very
!st trucks. The reason for this is that one large motor is more efficient
two small ones. A normal voltage has been adopted at 80 volts to
aspond with the minimum discharge voltage of the batteries adM>ted
110-volt charging circuit. Some of these motors are deeignea for
ation at increased speeds by shunting the series field with a resistance,
practice is considered by aome to be preferable to the praetioeof com-
Uing the batteries.
tterl
le standard equipment for the wagons and trucks is 44 cells of the lead
I of stora^ battery or 60 cells of the Edison t^pe and of a suitable
ere capacttv. lliese numbers permit of charging from the lighting
panics feeders at 110-115 volts with a minimimi loss in the charging
etat. Runabouts and other very small vehicles are eauipped with
r 30 cells of moderate ampere capacity, as a saving in weight is thereby
ined over 44 cells of smaller ampere capacity that more tEan offsets the
in the charging resistance. A battery can be supplied to meet almost
requirement of travel in miles per day. but it is generally found that the
^t of battery required for distances above 30 miles per day so reduces
sffideney of the automobile as a whole that the gain over other methods
ransportation is not so marked as it is with the battery of standard
le following lists of batteries may be used as a guide in selecting those
iny equipment:
Vhie Slectric gtoraga llAttory CoatpttMj.
Type MV "Exide."
TypoPV
lypo t"
Exide.
t«
iber of plates
iharge in amperes for 4
>un
7
21
9
28
11
13
15
49
17
56
19
63
21
70
5
12
7
18
9
24
35
42
11
30
of plates:
Width .
Height .
81 81 81 81 81 81 81 81 8f Sl \s\ 81
ride measurements of
ibber jara, in inches:
Length
Width
Height
12} 121 121 lit 12} 121 111 111 111
41
5
1
ft
Allow f inch above the top of jars for straps.
fri^t in pounds:
Element . .
Electrolyte
Complete cell
28f
31
35i
34
4§
41
39
5
461
54i
7
661
10
1
14i
14
2
19i
18
24
22
5
291
1228
THE ELECTRIC AUTOMOBILE.
CtoaUl S«ei«v« Battery C«na|
6f X 8f
TypeTP.
Plates
5J X8f
TypeNP.
nates
41 X 8|.
Number of plates . .
11
13
15
17
19
7
9
11
13
5
7 9
11
UD
Disoharce in amperes
at four-hour rate .
Oapaoity at four>hour
rate at discharge
42
168
49i
198
67
228
64i
258
72
288
21
84
28
112
35
140
42
168
12
48
18
72
24
W
1
Outside dimeneiona
of rabber jar in
inohfls:
Letigth ....
Wicfth
Heisht ....
5
6i
12
II
12
SI
12
U
12
8
12
II
12
n
12
n
12
5
6i
12
2
fflTlt
Weiffht of cell complete:
Founds ....
45
53
81
59
77
24i
311 38i 45i 14i I9i 24i 2H
To height of jar add i inch for fftrapa* and 1 inch for bottom of tray.
n«l«a fmr thm Proper Care mf
A battery must always be charged with direct current and in tiie zigiit
direction.
Be careful to charge at the proper rates and to give the risht amount cf
charge; do not undercharge or overcharge to an excessive desree.
Do not bring a naked flame near the battery while charging or in%ww*^AimtMly
afterwards.
Do not overdischarge.
Do not allow the battenr to stand completely disdiarged.
Volta^ readings should be taken only when the battery is chantDg or
discharging; if taken when the battery is standing idle they are of httb or
no value.
Do not allow the battery temperature to exceed 100^ F.
Keep the dectroWte at the proper hei^t above the top of the platee end
at the proper spedno gravity, use only pure water to replace evaporatioB.
Nev0r add ocuT except under conditions as explained in Uae instructkins.
Keep the cells free from dirt and aU foreign substances, both aofid tad
Uquid,
Keep the battery and all connections clean; keep aU bolted conneeCioai
tight.
If there is lack of capacity in a battery, due to low ealls, do not dofaij »
locating and brincing them back to condition.
Do not allow sediment to aoeumulate to the level of the platea.
BLBCTBOCHEMISTBT. — BLECTBO-
MBTALLUBOY.
Rbtisbd bt PitoivaflOBa F. B. Crocxsr and M. Arbndt,
OV COLUIIBIA UNIVXBaJTT.
itwlyatm i Th« Moaratlon of a ehemieal oompoimd Into its oonstlt-
Qente by meana of an electric currenL Faraday gktB the nomenclatnre
relating to electrolyala. He called the compound to be deoompoeed the
ISloctrolyte, and the prooeu Electrolysia. The plates or poles of the battery
he caUed Electrodes. The plate where the greatest potential exists he called
the Anode^ and the other pole the Cathode. The products of decomposition
ha called Ions.
Ix>rd Bayleigh found that a current of one ampere will deoosit 0.017258
grain, or 0.001118 gramme, of silrer per second on one of the plates of a sil-
Ter roltameter. the liqaid employed oeins a solution of silTer nitrate con-
taining from 16 per cent to 20 per cent of the salt.
The weight of hydrogen similarly set free by a eormnt ot one ampere is
,00001044 gramme per second.
Knowing the amount of hydrogen thus set free, and the chemical equira-
lenta of the constituents of other substances, we can calculate what weight
of their elements will be set free or deposited in a given time by a giren
current.
Thus the current that liberates 1 gramme of hydrogen will liberate 7.94
grammes of oxygen, or 107.11 grammes of silver, these numbers being the
chemical equivalents for oxygen and silver respectively; the chemical
e«iuivalent belns the atomic weight divided by the effective ralenoy.
To find the weight of metal deposited by a given ouiVent in a given time,
llnd the welsht of hydrogen liberated by the given current in the gi?en
time, and multiply by the onemibal equivalent ofthe metal.
Thus: Weight of sflver deposited in 10 seconds by a current of 10 amperes
== weight of nydrogen liberated per second x number seconds X enrrent
strength x 107.11 = .00001044 X 10 X 10 x 107.11 = .1118 gramme.
Weight of copper deposited in 1 hour by a current of 10 amperes =
.00001044 X 3000 X 10 X 31^6 = 11.86 grammes.
SInoe 1 ampere per second Uberatea X0001044 gramme of hydrogen,
•trangth of current m amperes
__ weight in grammes of ff. liberated per second
~ .00001044
— weight of element liberated per second
~* .00001044 X chemical equivalent of element
( Jamin and Bouty.)
Ohms per c.o. at
Ohms perOn. In. at
Density.
s.ri
SS3
8.
&9
Sri
Uo
1.1
1.2
1.26
1.3
1.4
1.6
1.6
1.7
1.37
14S
1.31
1.36
1.69
2.74
'4.82
9.41
Ma
JB9e
.940
1.30
2.13
3.02
6.26
.846
.668
.024
.082
1.06
1.72
2.76
4.23
.737
.486
.434
.472
.896
1.62
2.21
3j07
.640
J(24
jn6
.606
1.16
IJO
3.71
.409
.304
363
J70
JS12
JM
1.43
2.46
JI33
.262
.246
.280
.413
.677
IJM
1.07
.280
.191
.171
.186
JI53
JBM
J70
1.21
1220
APPLICATIONS OP ELECTROCHEMISTRY. 1231
itotABCM mf «iil|^lMit« of Copp«r a« lO^ C. or ftO^ JT.
^Bwlng and MacOregor.)
Ohms per
Ohm* per
I>eiiflity.
Density.
C.C.
Cu. In.
e.c.
Cn. In.
1X>167
164.4
64.8
1.1886
36.0
13J
14»16
134.8
63.1
1.1438
34.1
13.4
1.0318
98.7
88.8
1.1679
31.7
12Ji
1.0022
60.0
83.2
1.1829
30.6
12.0
1.0868
47.3
18.6
IfflRl
Saturated >
19.3
11JS
i.in4
88.1
15.0
llesiataMCM of «iilphat« of Sl»c •« IQo C. or ftO<» F.
Ohma per
Density.
Obmi per
Denaltj.
c.c.
Cn. In.
e.c.
Cu. In.
1.0140
1.0187
1.0278
IXXMO
1.0700
1.1019
1.1682
1.1845
1.2186
1.2562
182.9
140 JS
111.1
63.8
60.8
42.1
33.7
32.1
30.3
29.2
72.0
55.3
43.7
26.1
20.0
16.6
13.3
12.6
11.9
11.5
1.8709
1.2891
1.2886
1.2987
1.328S
1.3630
1.4063
1.4174
1.4220 )
Saturated )
28 JS
28.3
28.5
28.7
29.3
81.0
82.1
83.4
33.7
11.8
11.1
11.3
11.3
11J(
12.2
12.6
13.2
13.3
Specifie resiataDoa of fused todlom chloride (common salt) at wioiis
tamperatnres.
Temperature Cent. 720o 740o 760o 770° 780°
Ohms per on. cm. J84& .810 .894 .266 .347
Appllcotlona of BloctrockonUjti7.
The word electrochemistry is here used to include eleetromeCalhusy* M
there is no generic term for the two subjects. Electroehemistiy may be
defined as that branch of science relating to the eleotrioal proauotion of
chemical substances and chemical action or to Uie generation of ^eotrieal
eneigy by chemical action. On the other hand eleotrometalluivy is the
branch of science that relates to the electrical productKm and treatment of
metals. The two subjects are based upon the same prindples, the theory,
laws and data of one being applicable to the other. Hence it Is proper
and now customary to combine them under the head of eleetroehemistry.
Electrochemistry maybe subdivided as follows:
A. Kloctroljttc Cnhomistrr, which consists in separating or produo-
ing other action upon chemical substance by the decomposing effect of an
^ectric current or yice versa. Since the electrolyte is iJMally in the liquid
state, there are:
"Wet methods'* with solution.
*' Dry methods " with fused materials.
In tne latter case the materials are maintained in a state of fusion by the
heat due to the electrolytic current or by external heat.
12)32 ELECTROCHEBaSTBT.
Elaotrolsrtie ohemistry is applied to the foUowing, — ^
1. Frimary baUeriM, induaaos varioua forms oc Yoltaic oefl in
eleotrieal eaergy Ib geaerated by chemical action.
2. Secondary or aiorage hattervM are similar to the foresoins. bat tbe
chemical action must be reversible, so that after periods of workuiK the ed
may be ehaised or brought back to an active condition by sendij^ ttuv^k
it a current oppomte in direction to that which it generates.
3. BUetrotyping is the art of reproducing the form of type and _
objects by electrodepositing metal on the object itself or on a mold
tamed from it.
4. Elfidroplating is the art of coating artictes with an adherent layer ol
metal by electrodeposition, as in nickel plating.
& BleetrtUytie refining of melaU ond cftsmusoit by the »KTnl»^*|^f^ gf im-
purities, as in the oonveraion of crude copper into pure metaL
6. Steetrolytie production of meiait ond ektenieau, as in the Hall piute—
for eactiBoting aluminum from alumina dissolved in fused eryolite. stiid a
the Oastner prooew for making caustic soda and chlorine traax a aolatioa
of common salt.
7. Bleetrolytic chemical effeete, such as bleaohimi. tanning, ete.
8. Slectrolytio dtemical oiMlyeie, as in copper cwtennination.
B. aiectrotMannal Chemlstnr includes thoee meibods in vfaieh
dectric current raises the temperature of materials, usually to a
in order to produce fusion, chemical action or other MFeets.
trolysis is not desired an alternating current Is generally emplojped.
9. Chemieal aeHon tri^ electrical heaUnq^ as in the productiwi of
carbide from lime and carbon in an electric furnace.
10. Bledrical emtUinq consists in reducing metallio compounds at » high
temperature produced by an electric current, as in the reductioii of iroa
ore m an electric furnace, or in the Cowles process for "^nHng sifaimiinim
bronse trova a mixture of alumina, carbon and granulated copper.
11. Bledrie fimen of ehemieale, usually those that are ye^ reCrBctacx.
such as silica and alumina. It has been proposed to make bncka by nidt-
ing instead of baking day; dectric heat has been used in foraaoes §ot
melting glass.
12. Biectrioal heaHng and working of metala consists in treating metals
mechanically with the aid of heat generated b^ dectric coxreats. as is
deotrical welding, forging, rolUng, casting, tempting, etc
Strictly speakmg. the last two applications are not chemical^ bat aoose
chemical actions usually occur and they are similar to the others m methods
and results, so that it is customary to consider them under the head of
deotrochemistry.
C. Chemical Aettma Due t« Sl«c«rtoal BMmmWmwfptm.
13. Chemical effects of ^eetrical aree to produce combinations of nitarocBD
and oxygen, for example.
14. uKemical effeeta of eleelrie eparka.
15. Chemical effeete of eHent eledtrical dieduxrge, as in the produetiasi of
oBone.
Hietorical Notee. — The first electrochemical apparatus was the primanr
battery invented by Volta in 1799. The next year Nicholson and Cacfisto
discovered the chemical action of the dectric current in decomposing water*
In 1807 Sir Husophrey Davy gave his famous lecture "On Some CbemiQsl
Agendes of Eleetridty." he having, the same year, dlsoovoed the metals
sodium and potasdum by reducing their compounds dectrolytically. Ik
1834 Faraday established definite laws and nomenclature for dectro^MB-
istry. From 1830 to 1839 Jaoobi, Spencer, Jordan and Elldngton asplsd
these prindples to practical use in the making of dectrotypes. naftl
began the devek^Hnent of the storage battery m 1859. Since that ttsM,
but mostly after 1886, the theory and applications of deetrochemistqr
have made great progress, so that now it js one of the most importaat
branches <A science as well as of industry.
Priimssr J wtmA Bm^mmAtMPj Bisttoriea. — The various forms of these
batteries may be regsjrded as applications of electrochemistry, but thery are
treated as special subjects in other parts of this book.
Blectr«typt«g-. — To reproduce an engraving, typographical composi-
tion, or other object, a mold of gutta percha. wax, plaster or fusible aUoiy
is made from the object. If it is not a conductor it Is coated with graphite
to start the action, connection being made to it by a wire or clamp
1
APPLICATIONS or BLBCTROCHEMISTRT.
1233
aroand it. It ia used bb the cathode in a bath eonnsting of a 20 i>er cent
aolution of copper sulphate addxilated with 2*8 per cent sulphuric acid,
'while the best results are obtained with a current density of .2-.25 amperes
p«r aquare inch of oatliode surface. The anode is a plate of copper. The
ordinary thickness of deposit is .01 to .03 inch. The "shell" thus formed
is separated from the mold and backed by a filling of type metal.
Bleots«pl»tiafr an article with an adherent coating of metal requires
the artiele to be thoroughly deaned mechanically and chemically.
C71«tt»inff* — Solutions for cleaning Oold. SUver, C&pptr^ Braat and Zine
preparea as follows:
Hydro-
chloric.
For copper and brass
Bilver
ZIne
Iron, wrought . . .
Iron, east ....
Water.
100
100
100
100
100
Nitric
Add.
50
10
"i
3
Sulphu-
ric.
100
10
8
12
2
2
3
JAad, Ttn, Pewter, are cleaned In a solution of caustic soda.
Objects to be plated with gold or silrer must bo carefully and thoroughly
freed from acids before transfer to the solutions. Objects cleaned in Hoda
or those cleaned in acid for transfer to acid coppering solutions may be
rinsed in clean water, after which they should be transferred immediately
to the depositing solution.
liAtlM fer platlair* —The reader is referred to the yarions books on
eUctroplatinff for particulars, as but few, and those the most used solutions
can be referred to here.
Solutions should be adapted to the particular oMect to be plated, and
most hare little If any action upon it. Oyanideof gold and slWer act chemi-
eally upon copper to a slight extent and the objects should be connected to
the electrical circuit before being immersed.
Solutions are best made chemically, but can be made by passing a current
through a plate of the required metal into the solvent.
C*v»«r. — A good solution for plating oblects with copper is made by
dissolving in a gallon of water 10 ounces potassium cyanide, 6 ounces copper
carbonate, and 2 ounces potassium carbonate.
The rate of deposit should be raried to suit the nature and form of the
surface of the object, large smooth surfaces taking the greatest rate of
deposit. Electrotype plates must be worked at a slow rate, owing to the
rough and irregular surface.
AoiMiM/a//ic Surfacf may be plated by first providing a conducting snr-
faee of the best black lead or finely ground gas coke. Care is required in
starting objects of this sort, to obtain an even distribution of the metal, and
hollow places may be temporarily connected by the use of fine copper wire.
Oapper en iron or on any raetiQ that is attacked by copper sulphate is
effected by an alkaline solution. One which can be worked oold is made
up of i ounce of copper sulphate to a pint of water. Dlssolre the copper
sulphate in a half pint of water, add ammonia until all the first formed
precipitate re-dissoWes, forming a deep blue solution, then add cyanide of
Stassium until the blue color disappears. A heavy current is required with
is solution, enough to give off gas from the surface. This solution will
deposit at a high rate but ordinarily leaves a rough and crystalline surface,
aaa will not do good work on steel.
A cyanide solution is the most used, takes well on steel or brass, as well as
on iron, and permits of many variations.
Tor each gallon of water use :
Copper carbonate Soss.
potassium carbonate 2oxs.
Potassium cyanide, chem. pure. .......... 10 oss.
Dissolve about nine-tenths of the potassium cyanide in a portion of the
water then add nearly all the copper carbonate, which has also been dis-
solved in a part of the water: dissolve the carbonate of potash in water and
add slowly to ihe above solution stirring slowly until thoroughly mixed.
Test the solution with a small object, adding copper or cyanide until the
deposit is uniform and strong. For coppering before nickel plating, the
1234 ELECTROCHEMISTBY.
ooating of copper must be made thiok enongli to bUumI hard bulBng, aadte
this reason the coppering solution must be rich in oyanide amdnave jvl
enough copper to give a free deposit. Use eleoferolTtieallT deposited ttpftt
for anodes, as it g[yes off copper more freely. Begulate theevrreBtfordki
work in the tanks, and it should be rather weak for working this soiutka.
Bra$$ SoluHona of any oolor may be made '^ adding carbonate of tiaelB
Tarlous quantities to the oopper solution. Tne sine should be dissolved ii
water with two parts, by weight, of potassium eyaaide, and the niiitm
should then be added to the oopper bath. A pieee of work In thetaiA it
the time will indicate the change in color of the deposit. Two parts Mffv
to one sine gives a yellow brass oolor. Fbr the oolor of lig^t bi
little carbonate of ammonia to the brass solution. To darken the eolor
add oopper carbonate. Varying the amount of current will also ehangi
the color, a strong current depositing a greater amount of sine, thus pto-
dncing a lighter color.
Allver. — The standard solution for silrer plating Is chloride of rilfv
dissolved in potassium cyanide. This solution oonswts of 3 ounces silnr
chloride with 9 to 12 ounces of 96 percent potassium cyanide per ganosof
water. Rub the silTcr chloride to a thin paste with water, dasolvs I
ounces potassium oyanide in a gallon of water and add the paste, stinlsi
until dissolved. Add more cyuilde until the solution srorks freely. Tba
bath should be cleaned by filtering. Great care should be taken to ktv
the proper proportions between current, silver and cyanide. A weak tm-
rent requires more free cyafilde than a strong one, and too moeh eysaldff
prevents the work plating readily, and gives it a yellowiah or browukb
oolor. If there is not enough cyanide in the solution the realataiioe lo tk#
onrrent is increased and the plating becomes irregular.
The most suitable current for silver plating seems to De about one amper*
for eaeh sixty (90) inches of surface ooated.
Ci<aM. —Cyanide of gold and potassium cyanide make the best solntios
for plating with gold. The solution Is prepand in the same maDner ss tts
silver solution just described, using ohJoride of gold in place of chloridsof
silver. The electrical resistance c» the bath Is oontrolled by the qusntitT
of cyanide, the more cyanide the less the resistanoe, but an exeev «
cyanide produces a pale color. Hot baths for hot gilding require froB U to
w grains of gold jper quart of solution and a considerable ezceaa of cyanide-
Baths for cold gilding and for plating should have not lees than60grsiB»
per quart and may have as much as 2SSb grains, this quantity being used vitk
a dynamo current for quick dipping.
lllckel.— The solution now almoet universally used for nickel ptodsf
is made up from the double sulphate of nickel and ammonia, with tte
addition of a little boracic acid.
The double salt is dissolved by boiling, using 12 to 14 ouncee of the sslto
to a gallon of water; the bath is then diluted with water until a hjdrom^»
shows a density of 6.5<> to 7° Baum^.
Cast anodes are to be preferred as they give up the metal to the solotkn
more freely. Anodes should be long enough to reach to the bottom of tto
work and should have a surface greater than that of the objects b^ng plit«K<
Current etrength should be moderate, for if exceesire the worku Wt(i*
be rough, soft or crystalline. Voltage may vary from 3J^ to 6 volts and tie
most suitable current is from .4 to .8 ampere per 16 square inclies iiiH*^
of the object. Zinc is the only metal requiring more current than this, ^
takes about double the amount named.
A nickel bath should be slightly add in order that the work may bsve ft
suitable color. An excess of alkali darkens the work, while too much acid
causes " peeling.'*
Iron. — A hard white film of Iron can be deposited from the doibi*
chloride of iron and ammonia which can be prepared bv the eorrcBt
process. It is somewhat used for coating copper plates to make ttxa
wear a long time, the covering being reneweid occasionally.
The SHeciromotiTe forces suited to the different metals sro:
Copper in sulphate Volt, 1^15
** cyanide 4.-6.
Silver in " 1, -5.
Gold in " .W.
Nickel in sulphate 2.$^
THE ELECTROLYTIC BBUNINQ OF COPPER.
1235
Resistance will depend on the nature of the snrfttoe. Work it
b€st effeoted with about equal surface of anode and objects, and the coating
will be more eren, the greater the distance between them, especially where
tlMre are projecting pointa or rough surfaces.
Cbopsr and stiver siiould nerer Mkow anv siffn of hydrogen betng given off
at the objects; gold may show a few bubbles if deep color Is wanted.
Klokel ia always accompanied with cTolution of hydrogen, but the bath
sboald not be allowed to froth.
VMe Mate ef Depealt is proportional to current, as described under
tbe bead of " Blectrolysis," in the proportions given in the table of electro-
ebemlcal equivalents except in the case of gold, the equivalent of which in
eombination with cyanogen is 196.7, but sul^ect to roodiiications dependent
upon the hydrogen action just described; there is also a partial solution of
the metal, so that there Is always a deduction to be made from the theoret-
ieel Talue. Thus : — .
Qold gives about 80 to 90 per cent.
Nickel *' 80 to 95 **
Silver ** 90 to 96 **
Copper " 96
(•
An ampere of current maintained for one hour, which serves as a unit of
quantity called the "ampere-hour,** represents
Gramme
Ounce Troy
.0376
.00121
Grain . . .
Ounce Avoir.
58
.00132
which multiplied by the chexnical equivalent will furnish the weight of any
substance deposited.
The Klectroly-tic Ileflalag- ef Copper.
The largest and most important of electrochemical industries is copper
refining, conducted at many places in this country and abroad. The pro-
oess of refining copper electrolytically consists in the transfer of copper
from the anode to the cathode, by the selective action of the electric cur-
rent, and in leaving the impurities behind in the anode, electrolyte or
sediment.
Theoretically the mere transference of oopjper should require no expendi-
ture of energy, the oiergy needed to precipitate it from its solution being
balanced by the energy set free upon its change to copper sulphate, but
practically some is needed on account of the resistance of the electrolsrte,
and differences in mechanical structure as well as in chemical purity of the
anode and cathode.
The material at present subjected to profitable electrolytic refining is
crude copper containing from 96 to 98 per cent pure copper and varying
amounts of other elements according to the character of the ore and mewod
of diy refining adopted. The composition of the crude material varies
atly, typical samples being given m the following table:
No. L
Percent.
No. II.
Per Cent.
No. III.*
Per Cent.
Copper . .
Arsemc . .
Antimony .
Lead . . .
Tin . . .
96.35
0.08
0.10
1.19
0.22
0.05
0.61
97.19
2.68
0.01
98.60
0.80
0.10
0.10
Bismuth .
Iron . .
Nickel .
0.08
0.02
0.02
0.06
0.10
0.10
Sulphur
Silver
0.69
0.10
0.05
Oxygen and loss
0.71
100.00
100.00 10.000
•Chitibar.
BLBCTBOCHEUIBTRT.
The enids mtMttel i* out in ir
(eat ]oag, two f«et wld*. and dim Ineh thick, wdchiiic atn/nainmtitr
poondf. Tha nttude phtoa an of alsetrolytinl^ n6iwd oodpar pn
<ally (be mae in Itocth and width u llie BDodia but only OM-tnal
inoh ttiiok. Tba eleotndyt* or bath in wluoh tin pintia are i
•olutba of 12 to 20 iter cent of^iper lulphate. and 4 to 10 per
aeid, the latter boos added lo daci^ue tba nditaooa al tba a
Tfitir"'** 11 furtber reduoed by ''■t"'w the eLeatroEyta
♦0°C.
Tba ooDlaioing tanki are of wood, mually Iu>nr1 wit
Darefuiiy eoatad with a plteh cotopoimd, and rd i
a pitel
some caaea tbe platee %j* arransed in aefiea. and in o;»»- ».
lultJpie. aa illiutr*t«L Tha former bM the adiniBla«e of leqiuiins
"leal ooanectiona to ba roada at the fint and la«t plataa aulj. wfaui—
eleotrieaf ooonactiona
Fio. 1. Sarin Arrangement <d FlatM.
equina a conoeclion at erery^Uta: but ii
d tha eire«dt ia tbe paialU
run at two diffemt Wda
^ and one for e>thod«. In
d V (bape, ■> th»t theadseawiD
mt tbimish any oi
taot. The drop in , . . _ „._
*« arranged ao tbat eaob La am i—ililii ftota all ■
tioa of the electrolyte ie poinUe. This circulation may be obtsined br
blowing a Btree.m ol air tbroush tba alastroiyte, but more b«quently tr
. ^J tiig vata in ei«pa and coonaotiDC them by plpea ao tbat tbe elae-
may pass from the <op of one vat to the bottom <rf tbe next, a*
a Fist. 3 and 4, Tbia maintaina a unifOim deoiitv of tbe alectrolrta
T inportatit, b
1
THE ELECTROLYTIC REFINING OF COPPER. 1237
•md anenie if preMnt would prevent the use of a current deuity of more
than 10 amperes per square foot, aa they would be carried over and dqwe-
ited, especially if present in a soluble form. The maTJmum current density
oBDipioyed in ordinary copper refineries is as above stated, 10 to 15 amperes
l>er square foot. If the current density is too Rreat the following difficulties
isdll occur:
a. libecation of hydrogen at the cathode, and thus a resultant waste of
b.FooT charsoter of deposit.
If the current density is too low, the copper is in the tanks too long,
and this rssults in eonessive interest ehanBee.
The individual vats are connected in series with each other, so that the
total voltage required may be i^pproadmately equal to that of the gener-
Fio. 8. Oreulatinc System.
ator. allowing the usual drop of about 10 per cent. Standard generators
are built to give 125 volts so that a working pressure of about 110 volts is
obtained, which is a standard value for lighting and other purposes.
In practice from 400 to 450 ampere-hours are required per pound of
copper d^Moited, the theoretical amount according to Faraday's Jaw being
H-
l t
I
i\
Fio. 4. Qeneral Arrangement of Plant.
only 386.2 ampere-hours. The loss varies from 4 to 20 per cent, according
to the syvtem employed.
AM«de iMpvrltlee aad tkelr BiTect nposi «b« Klectroljt«. —
The eieetroljrte when first added consists of 12 to 20 per cent copper sulphate
and 4 to 10 per cent sulphuric acid. The impurities likely to exist in the
crude metal anodes have been given in the sample analyses preceding,
and the following reactions generally occur in an acidulated solution:
1. Silver and gold remain undissolved in the anode or fall to the bottom
of the vat.
2. Lead is converted to lead sulphate and precipitates.
3. Antimony, bismuth and tin are part.ly dissolved as sulphates, or
form unstable sulphates which precipitate as basic sulphates or oxides:
they partly also remain in the anode sludge.
4L Arsenic, nickel, cobalt and iron dissolve, but are not under ordinary
conditions redeposited, hence they merely contaminate the electrolyte.
1238 ELECTROCHEMISTRY.
5. AllukliDe earth metals except barium and cakimn diaaohre iiiailHy
the latter predpitatios as sulphates.
In addition to oontaminatinc ihe electrolyte and thus interferiiiff *ni>
the purity of the dqxMrit the preeeDce of theae impurities, except cold.
■Uver ana lead, is objectionableb due to the fact that the anode ia
unevenly. The more electropositive metals such as tin, sine, etc, besH
more rapidly attacked, the anode surface does not remain smooUi. na
frequently pieces break off and fall to the bottom of the tank. Arasae. if
present, often forma arsenates on the anodes, which results in a noB-eoa-
duclinK film, decreasing the currait and thus the output.
Bffect of the Cloctrol jto KMi»«rita«s •■ Om WB^mmaMt. — The
electrolyte does not aocmnulate all the impurities of the anode Deeauaeiaany
of them never ^o into solution but simply fail to the bottom of the vat ai
mud. In addition to the proper constituents of the electrolyte there oksy
be present in the dissolved state the sulphates of iron, sine, ff»Hg*i»n"« ahh
minum. sodium, etc., besides basic sulphates of arsmic, bismuth and anti-
mony. The lanest part of the impurities present consists of irtMi, but the
most objectionable are compounds of arsenic and antimony, as these yidd
their metals at the cathode, with serious results, since as little as .01 pv
cent of either will reduce the electrical conductivity of copper from 4 to 5
per cent.
Cuprous oxide and copper sulphide remain partly in the aludge aad
partly dissolve according to the acidity of the electrolyte. Their otkly evfl
effect is to neutralise some of the free sulphuric acid.
The composition of the anode sludge (residue) will evidently vary as-
cording to the composition of the anode employed, and in praotioe variasi
amounts of gold, silver and lead are obtained therefrom by snlwwimiiirt
treatment.
The cost of refining copper by the electrolytic method ia from | to }
cent per pound. The following products of refining are mariceted:
mercial cathodes, which are sometimes shipped to oonsumeia but
frequently cast into wire bars, ingots, cakes or slabs of standard
and weight. Thev usually assay from 99.86 to 99.94 per cent of pure
per, a sample analysis being as follows:
PEB CENT.
Copper* 99.938
Antimony .002
Iron .004
Oxygen and loss .056
100.00
The yield in commercial cathodes is from 97 to 99 per cent of the anodes
treated, excluding the anode scrap which varies from 7 to 15 per cent of
the original anode in parallel operated plants; but this scii4> ia not a loss,
as it is collected and recast into anode plates. Besides eleetrolytie copper,
most plants reoover gold, silver and mckel from the slime as previoudy
stated.
The electrolytic copper refineries in the world are now producing copper
at the rate of 322,29d tons annually, valued at 196 .688.500 with copper
selling at $300 per ton. In addition the byHproduct in recovered gold iad
silver is valuea at $20,000,000 per aimum. There are now in active open-
tion 33 electrolytic copper refineries, with a total generator caiMuatv of
20.000 kilowatts; 10 of these are located in the United States aad supp^
about 86 per cent of the world's output; 6 plants are in England and Waw
producing about 9 per cent, while the remaining plants are on the eooti-
nent of Europe,
Silver is refined from copper bullion by taking anodes of the buHkn i
inch thick and 14 inches square, and cathodes of sheet silver slightly oifea.
The electrolyte consists of water with 1 per cent of nitric acid. Wbcn the
current is started the copper and nlver form nitrates of copper and abrer
and free nitric acid from which the silver is deposited, leaving the copper
in solution. Trays are placed under the cathode for catching the depodted
diver, and if there is any copper deposited owing to the soiudoQ contun*
*Thi8 sample was obtained by refining the crude cc^per g^yto. m
column III of the preceding table of crude copper anodes.
PBODUCTION OP CAUSTIC SODA. 1239
ins too Utile lilver or a BUperabimdance of copper, the oopper fallfl into the
tnure and \b rediasolved.
In the Moebitu proeeM the dmoeit ia oontinually lemoved from the
cathode by meana of a meehanioai arraogemeDt of bniohea, and falU into
the trays above mentioned.
^A.lHmlBMMi. — Praotieally the output of this metal for the entire world
ia now produeed eleetrolytically. The only prooeea uaed on a large eoale
ia that invented independently in 1886 by Mr. Charlea M. Hall in the
United States, and b^ Paul L. V . Hdroult in France. This process consists
in electrolysing ahmuna dissolved in a fused bath of cryolite. The alumina
ia obtained from the mineral bauxite which oocura abundantly in Georgia,
Alabama and other regions. The natiual material, beinc ^ hydrated
alumina containing silica, iron oxide and titanic oxide in the following
pn^jxxrtions:
AlsOt .56
FmO. .03
SiO, .12
TiO .03
H|0 .26
muat be treated in order to drive off the water and eliminate the impurities.
Thia may be accomplished by a chemical process, but it is effected more
simply by heating the material mixed with a little carbon as a reductng
asent in an electnc furnace. The impurities are thus reducMi and collect
aa a metallic reculus in the bottom of the mass. Thia leaves the alumina
nearl^r pure and it may be tapped off while fused or easily separated by
breaking it up after cooling. In practice it requires two pounds of alumina
for each pound of aluminum produced. The flux or bath in which the
alumina is dissolved consists of cryolite, a natural double fluoride of alu-
minum and sodium (Al2Fo.6NaF) found in Greenland. This is melted in
a lar^e carbon-lined, rectangular, sheet-iron tank, which constitutes the
negative electrode, a group of 40 carbon cylinders, each 3 inches diameter
and 18 inches long, which are suspended in the tank, forming the positive
electrode. A direct current of about 65 horse-power at 5 to 6 volts is used.
Only a portion of this voltage is required to decompose the alumina, the
balance, amounting to about two or three volts, represents the heat pro-
duced which keepe the bath at the proper temperature and fluidity neces-
aary for electrolyria — 850 to 900^ 0. The passage of the current causes
the aluminum to deposit on the bottom of the tank as a fused metal, being
drawn off periodically. The oxygen set free combines with the carbon of
the positive electrodes and passes off as carbonic oxide. The reaction is
AlaC^ + 3C — 2AI + 30O. About one pound of carbon is consumed for
one pound of aluminum produced. When the alumina becomes exhausted
from the bath, the voltage rises and lights a lamp shunted across the
electrodes, thua giving notice that more material is needed. Each elec-
trical horse-power produces about one pound of aluminum per day of 24
Inyurs. According to Faraday's law the weight of aluminum deposited by
1,000 amperes is .743 pound per hour. The actual jdeld of metal by the
Ilall process is about 85 per cent of this theoretical amount.
The aluminum obtained averages 0.1 per cent iron, 0.3 per cent silicon,
with traces of copper, titanium and carbon, but is guaranteed over 99 per
cent pure.
The metal when drawn from the tanks is cast into rough ingots which
are afterwards remelted and converted into commercial shapes such as
aheets, rods, wires, etc.
nio]»i7cacMO]V of causimc «o]»a.
Caustic soda or sodium hydrate (NaOH) is used in the manufacture of
hard soaps, in the rendering of wood pulp for paper manufacture in the
purification of petroleum and petroleum residues, and also for the produo-
tion of metallic sodium.
Many attempts, extending over nearly a century, have been made to
manufacture caustic soda maOH) and chlorine (CU) from ordinary salt
CNaCI), by means of electroljrtic action. The fundamental reaction:
2NaCI + 2HsO + Elect. - 2NaOH +H9 + CU
1240 BLBCntOCBBiaSTBT.
if nadilv obt»ln«d apsinwiUlT. but ii diSoult to Moomnlbh o
menial buu. 3kJt. or (odiuiD cUoridB, when elsoIroIrHl^n the .
' ' It Haondkry raoMioiu taka pteoa ftndtkB
a utd hrponliloRta at bocIk. ^lia dift'
- ■' luitio »dk Mdutina ttakt b fen— I
rsr p«r unDm (24 boun p«r dky).
I. Th» I ' '
3. TIh elsitradaa miut ba u iMBrijr indsctnuitiUa M ,.
4. Tbe prodiwu of etoctrolyu muat be o^Bble of n
TwI or clHitnilrte i ■'- '-
nET^wU.'
„ . Ji (SSO- C).
Tha Cutaer pnwgaa cmplojrad in this eoontry at Nianra 1
follow*: Tha ataetrDl>-tui lank mnasta of a aUta box « f«M la
Fia. S. Cattaa Gall.
nlda and 0 Inshaa daep. tha joiata baina mada by maani.af a nibber eamat.
Two alale pwiitiaiu naehioc wilhia ^ iaoh of tha bottom (UDdar wbi^
mn iroovaa) divide the oell Into thne ooupartnUDla. eaoh IS ia^tea bf
4 faet, aaaled from eaoh otbac by a layer of nMimiiy oovninc tha boCUa
of the tank to a eoiuidenbl* dipth. Tha two cod oompattiBenu thm^
which the brine ia paased are provided with carboa aoodea, ahjaped lika a
rail eenUon. the broader flance btinc pboad about a half iadi sbove tht
mercury. Theee eempartmenta are provided with tl^ht cidvwb and a»
humt pipe* of rabber and lead to ooavey tha ohioriBe away. TTw aninl
eompartment ha* an lion cathode eompoaed of twenty upiicbt Mripa iDd
it luppliad with pura water, whish ia dtaws off wbaiani lta,apecifie C"*^
increaaea to 1.27rdua fo the prcMnce of the maufacturMl oauaiie, ^A
the libanied hydrocen ia led (ram thl* ohmbar by maaoa << pipa* lad
uaed aa a fuel for the awkoentntion of tbe oaiatte. Tte tank ia nvolad U
one end on a knife-blade and reela at (h* otbv OD an eeoaatrie. wtuch nka*
and bwara that and of the tank ^- ' '- -
ween the (ut«r and middle oompart-
r ehambara, ifilila up the aodiiiia
hum and oblonna (Na and CI), lb*
ride (oommon Hit. NaCl) into udium and oblonna (Na and CI), lb*
IT ii Ubeialed at the caibon anode* and paaaea thiouch the ecbaoal
to tha abaonitiou ohambara, when it eonbinaa with alaekaJ lime to
PRODUCTION OF CAUSTIC SODA. 1241
form. b1«ftehiiig powder (GBCl«O^CaCI|). The sodiiim oombmes with the
mercury, forming an anoalgam oontatning about 2 per cent of eodium,
wfai/'h by the tilting of the tank paaaes to the central chamber, where it
•erver as the anode, and combines with the water to form caustic soda
(NaOH) and hydrogen (H>, the latter appearing at the iron cathode.
Bach of these tanks uses 630 amperes at 4.3Tolts; 10 per cent of this
current is shunted around the inner cell, because otherwise the amalnA
would fail to detiver enough sodium, and the mercury would oxidise, thus
producing mercury salts and contaminating the caustic. The theoretical
Toltage required is but 2.3, the remainder being utilised in overcoming
the onmic resistance of the electrolyte and in keeping it warm, the limit of
temperature being 40^ C, as above this point chlorate is formed. The
output of this process per horse-power oer day is 12 pounds of caustic and
80 pounds of bleaching powder tor each cell. The product contains from
97 to 09 per cent caustic. ^ per cent sodium carbonate, .3 to .8 per cent of
sodium chloride and traces of sodium sulphate and silicate.
The Acker process, formerly used at Niagara, for obtainin^s caustic soda and
ehloiine from salt is dmilar to the Castner-Kellner process just described, but
differs in that it employs molten lead in place of mercury as a seal, fused salt
instead of brine as the electrolyte and operates at a temperature of 850** C.
which IB required to maintain the fused condition of the electrolyte. The
containing vessel is a cast-iron tank five feet long, two feet wide and one
foot deep, the sides above the molten lead being eovend with ma^esia so
that the current must pass from the carbon anodes to the lead which aets
as the cathode, the lower faces of the anode blocks being three-fourths
inch above the lead. At one end of the tank is a small compartment
separated from the remainder of the vessel by a partition dipping into the
lead to such a d^th that nothing but this fused lead can pass ^m one
oompartment to the other. The chambers are loosely closed by fire-clay
slabs and the escaping chlorine drawn away through mde flues by powerful
exhausts. In the smaller compartment the lead is subjected to a stream
of steam, which, Acting upon the lead sodium alloy, forms caustic soda and .
liberates hydrogen, 'ijm steam jet is introduced below the surface, but
pcunts vttrtically upwards, and the resulting spray strikes a curved hood
which deflects it into a third chamber in which the lead and caustic sefwrate,
the latter flowing out of the furnace over a cast-iron lip. the lead sinking
and passing back to the main chamber, while the evolved hydrogen is con-
ducted away. The fused caustic is collected in an iron pan where it solidifies
and is removed every hour. The output is 26 pounds o£ solid caustic per
hour. This process avoids the evaporation of the water required in the
Castner-Kellner prooess, but higher maintenance costs offset this advan-
tage, llie current employed per vessel in the Acker process is 2100 am-
peres at from 6 to 7 volts^ of which energy 64 per cent is used in chemical
aetion and the remainder m maintaining toe temperature.
The same methods that have been commercially successful for the pro-
duction of ca\]stic soda and chlorine from salt are used to produce caustib
potash and chlorincw Caustic potash is of value for the manufacture ci
soft soi^M, the preparation of oxalic acid from sawdust, and for the ex-
traction of metallic potassium. The raw material, potasdum chloride (KCl),
is more expensive than sodium chloride, costing approximately four times
as much,* so it is an advantage to ^employ the electrochemical process
which is more economical in raw material than an ordinary chemical method
wouldbe.
Prodnctl^B •f Metallic 0o«lliiiii. — This metal was formerly ob-
tained by the reduction of its carbonate or hydrate mixed with carbon, but at
the present time all the metallic sodium emploired in commerce is obtained by
means of the Castner electroljrtic process. The raw material is solid caustic
which fuses readily at a low red heat and is obtained by the Castner
caustic prooess already described. A diagrammatic view of the apparatus
is shown in Fig. 6. The containing vessel is of steel, the electrodes are
usually of cast iron. The electrical pressure employed is about 4.4 volts
direct current, the action being as follows: The vessel is placed in an ordi-
nary furnace flue, in which the gases are at a temperature high enough to
iPf<Vititiw the caustic soda in a fused state. The curroit enters at the posi-
* NaCl oosts 10.00 per ton; KCl oosts S37.05 per ton.
1242
ELECTROCHEMISTBT.
tive electrode, which is a hollow cyUnder provided with vertiesl ..^
to allow free circulation of the electrolyte. The necattve ctoetgode ie
at the bottom of the veMel, and terminatet in the vaoe in tbe '^
the anodew A cylinder of iron wire gauie is placed between the e
its function being to prevent the eoparated sodium from a>readtm_ .
the entire surface and coming in contact with the oacygea Ubecmted aft the
anode. The extreme fluidity of the fused eaustio, however, allowa ift Is
pass readily through the gause openings, while the greater surCaoe
of the liberated sodium will not allow it to pass through the
metallic sodium in its fused state has a lower necifio^ graTi'
fused eaustio, hence it remains at the surface, and is f " *
to time. The liberation of hydrogen at the cathode
metal from the possible action of the oxygen.
gat^eeiM Cbloimto is produced m considerable quantities both heie
and abroad. The Qibbs prooess ueed at Miegaia Falls ooosists in tfas -^^
to prataet tbe
Fig. 6. Gkstner Metallic Sodium Electrolytic ObH.
trolysis of potassium chloride solutions, uring a copper or iron eatfaoiii
and a platinum anode. The ceUs are compoeed of a wooden frania, i.
covered with some metal, B, such as lead, not attacked by the eleetm^yta
The latest form of cathode consists of a grid of vertical oopper wires, C.
kept in position b^r crossbars, />. of some insulating material, ae sbofes m
Fig. 6. The grid is placed in a vertical position against one side of Ai
cell frame, and kept in place by the anode of the adjoining cell, from eiich
it is insulated by the strips, F, and bars, D.
The opposite side of tne cell from that occupied by the eathode is per-
taallv closed by the anode (see dotted lines of Itf . 7). This consists of ft
thick lead plate, L, covered with platinum foil on the outer side. B (Ff( 8)i.
This anode is held in ixMition by the eathode and framework of the fdo*>
ing cell. G is a pipe, reaching to the bottom of the odl. by whkdi the po-
tassiiun chloride is continuously supplied, and H is the overBow p^ to
eonvev the mixed solution of the chloride and chknate. as well as tbs IB^
erated hydrogen gas away from the oelL 8, 8, 8, 8 are luga |ii ujuiIIbc
PRODUCTION OP CAUSTIC 80DA,
mm tbe tmneworfc, by mouu of vUah bdv number of Mlb eao b* bolted
osBthx to form ■ hiUs of oalls. Fig. 8 abom ■ eroup of three oelli. tha
lekvy pbtCB (X tod r) beiog lued lo eloae tbe eodi of (he voDdeD fnme-
Fork. ukI foim k fully cloeed eeriee of oelU with the ooly opeuinca at the
t«d E^ieite
b of the euppty pipM O. i..
■.uB jBw ui Bupply b«inE so rqrulalAl lu
oell »t 50° C, ud Che unount of chlon
mider 3 per cent.
Since tbe platee C and L of vaoh c^
lead Haiiis. the eleetrolyida oocuis bet'
CMthode 01 the followiuc oell (Me nan
n of pobuMum chloride,
intain the temperature of tbe
M diaohais^ loJutioD alishtly
nV-
n
?
titmiti
IIIIIIIIIIIIIIIH
iiiiiiiiifiiiiiii
'
si
^^M
"e
"-
3
Fia.7. OibbaOeU.
belu nc
n one-dghth inch w
a BrB allowa the elentTolyla to dreulate
pamnn upwaide and out of the celle at H
The per«iit«Ae of ^'-' — *- ~ "" ■
fiifferatUHi is neoeeeary
flieetrolytu ohlorata pi
tank. rihe.elMtro^
Plti. 8. Oibhe Cell.
t fact that the cathode !•
ii of which tl
in the overflow acdution ii low.
'er <t, and Fis, B is a npreeanutii
retri(Brmlori, anil P
whUa the ohiomte preeipitatee
it oryitaUiie out i
r^rd t<
~of'cbtol^,
would if prei
. .^ .^ntaininf only 3 per cer
laltet will Dot oryitalliie out upon natural fwliag, at 11
in larse quantitiee. Thie low perceatage of ohlorate preei
obt^n Quiflk reoorery, as otherwise the preaenoe of the hydroffea will et
Beoondary reactiona. and cut down the effieleacy of tbe oonvenion.
pnanire employed is about four volts per oell. of which 1.4 ia reqmi
eonrort (he ohloiide hito chlorate
eKCl t- enfi *■ Elect.- flEOH 4- 3H, *■ 3Cti
' SKOH + m'i + 3a,~ 2Ka.O, + 4KCI -I- 3t^
and the remainder producea the heat that ma
which is nesessary for the pioper reaction.
etajit consista of fifty such oeLLi, connected up into two at
1 series. A direct curreot of 10,000 amperes is auppKsd
iridch, allowing for Line drop and loeeea at cell contacts, gi
electrolyte at G0° C.
nt denrity is high.
I. At Niasanttie
i
1244
ELECTROCHEMISTRY.
Sleetrolytie ehemieal effects such m bleaching hare been prodneod i>««
the action of chlorine or other matter set free by an elactiie omrcnt.
ii poeeible in thie way to caiMe subetancea to act while in the naeceat
and therefore more powerful. Disinfecting and deodoriaJng of ec
also been acoomplisned in a similar manner, as in Uie Wbolf p
Fig. 9. Arrangement of Gibbs Prooeas.
the eleotroljrris of a salt solution mixed with the eewageL The
of the current liberates (CI2) chlorine and sodium hypochlorite (NaCK)).
which act i^>on the refuse matter.
Bleeirolytie dtemioal analyeia is a special mibieot, the diacoaaion of wtaA
is usually confined to books and journals relating particularly to ehenkal
analjrsiB; it is not ordinarily considered in connection with the
subject of deotrochemistry.
2.
3.
4.
6.
Klectrotherasal dtcHalatry includes those methods in whicii an <
trie current raises the temperature of materials, usually to a htsh d^prm,
in order to produce fusion, chemical action or other effects, ^xuern '
trqlysis is not desired an alternating current is generally employed.
The effeot on the materials and the amount of product obtained is
or lees proportional to the heat eneri^y dereloped in the fnmaoe. Wlals
the heat neoessary to i>roduce a oertam change in a given suaaount of na-
terial is perfectly definite, the heat lost by radiation, conduction, ete., is
variable, so that the efficiency must always be less than 100 |»er eoit.
The proportion existing between the heat ener^ employed in an electtie
furnace to produce a desired phsrncal or chemical change and the total
heat suDplied is termed the ^denoy of the fumaoe.
The degree of efficiency attainable depends upon many fkcton:
1. The siie of the fumacei
Neoessary temperature for the desired reaoUcm.
Protection from radiation.
Arrangement of terminals.
Method of recharging, continuous operation being moat eoonamicsl
as the heat of the fumaoe walls is ret«uned.
6. Method of removing the charge, it being undesirable to destroy •
fumaoe to get at the charge.
The most important of all these connderations is undoubtedly Um ■■
of the furnace, stnoe the radiating surfaoe of a small oanaaity is relatmir
greater than that of a large furnace. Consider two cubical fumaeea: ess
of 1000 units' volume, the other of one unit's volume, the radlatii^ soziMMi
would be 600 square units for the former, and 6 for the latter; fisnes Ike
radiating surfaoe for the smaller would be ten times larger per mlt ca-
pacity and the losses would be in the same ratio.
Electric fumaoes are divided into three general olaases as follows:
The material may be heated by pmwing oumsA
directiv through it.
The material may be heated by the heat gea-
V erated in a conducting core.
The material may be acted upon by heat radiated
from an electric arc.
^ The material may be fed through an are atresia.
Where the charse is oonduoUve and is heated b;
currents inouoed in it.
a. Resistance Types. "
h. Arc Types.
e. Induction Tsrpe.
ELECTBOTHERUAL CHBICIBTRT. 1246
TlianhwnfirMiifc oocoirinc in a tumaoa msr bt aubdiTlded m bUam:
a* ne^tjQc fthm« without fuooa, ai in th« nunufuturv ol gnphibL
fc. HaMios uid fuiian. u in tba tnatment of bauzits.
B. Heating add ohtmieal chaiics witluut fuBOB, m in tli> manufutim
of ^arbonrndum.
d. Heating, fuiioo and cliamioal oliaiiBs. ai In the numutacture of laldium
CAldsai C^tftlde. -^ This oompouiid ij produoad by an eieatrathflnnal
prooaaa iavrated by Willaon in Iwi. the total oulsut throuihout tba
world btbiM about 300.000 tooa in 1002. lu value lis in tht laot that 1
pauod of thia (ubMaoo* mixed with watei produew thaoraUeally S.S and
aotually about 5 oulua faet of aeetyle&e, equivalent in iliuDOihaUng pDWtt
to about TO eubie Teet of otdiuaiy gaa. IIh raaoljoa yiakUu aoetytana k
CaC. + H^ - CaO + C^II» Variou* (oimi of eleotrie futnaoe hare ben
emfnayad in the production of oaldum carhida Ona type inivited by
Kins and nnnagated in Fie. 10 oomiMt of an Iron car. A, whieh holda tba
matarialf and eatUde, at the «me time ai
daotrod<b It ia run intoplaoeornmr""'
knd baiiu provided wiUi tiuanlou il
ba tipped out. The otha eleotrod
1 heavy rod, C,
;thaDed by ma
utaiial led tlu'oush tl
re of 1 tonoTbui
B to pndiwe 1 too trf earbide,
J +30-0-" ■ ""
the reaction bekc CaO ■!■ 3C — CaCi + 0-.
ia fitat formed between the eleatrode, C. and the Boor
of the tniok. Tba reaultioa hich tsnuHrature ao-
verta tbe mixture into eailnde, tlie eUctrode being
g:Tadually laiasd and mora inatarial added imlil tlia
Bar i* nearly filled with the product, when it ia rtni
out and rqilaoed by aaotlier. At Niagara EUb a <
rotary fono of furnace Invented by C. S. Bradley
ia uHn. being operaltd oontiQUously and producing
kbout two tool in 24 hoon when lupplisd with 3.300
ampana at 110 volti. or about 500 luHafr-power. Fia. 10. King Car>
Since no electrolytic action ii required, an altama- bide Fumaae.
tinjl eurtent ia employ ad.
Cor^w-widnm ij a oommercial name for oarboa tilifli^fr (CSi) produoad
■--' irdlng to the invanliona of :* " ' ' --j ■-■-
aa an abraiiva. tHiog hard a
-_rmed by Inlaoaely beating ii. .^
luuiura of 34 tons of ground coke. 0 tons of ^uid
1^ ton* of lawduit and aalt, tba yield being 3 oi .
eryitaltiae carborundum and about aa mucli moie of the
'loui material. Tha fumaee* uaed at Niacam Falla
ol Gre-briok hcartba 16 feat long and S feet i ' '
c
1246 ELECTROCHEMISTRY.
of thA carborundum process — when the core is too aanall the heat
excessive and it is reduced to graphite — the silicon volatiliaios. Arlwi's
experiments indicate that all metallic carbides are decomposed by
application of intense heat, the metal constituent volatilinns. the
remaining beliind as practically pure graphite, and his pat«it8 are *
this theory.
The commercial work of the Acheson Company is in two lioea
A. Oraphitifling formed carbon objects.
B. Graphitiang anthracite coal en masse.
The product in every case is pure gn^>hite.
In case A . the matoial to be grapnitised, is stacked on in a fureaee be*
tween the electrodes as a partial core 2 feet square and aibout 30 feet koL
bdng thickly covered and the spaces between the pieces filled with a ^b^V
ground mixture of carbon and carborundum, alternating cnneat «■ :
3000 amperes at 220 volts is applied, and changed to 90CK> amperes si \
80 volts before the end of the run of about 20 hours. i
In case B it is found that the best results are obtained if the eore ese-
sists of a rather impure form of carbon, one which when burned at oaBamj \
temperatures would leave a large percentage of ash (10 to 15 per oast). ;
This is ground to the sise of rice grains and used as the fumaee cbsiR |
with a conducting core of partiallv graphitised carbon, about 1000 Hx. j
of alternating current being applied for 20 hours. I
Altmdum, the trade name for artificial corundmn, is an abrasive nodi •■
by a process due to C. B. Jacobs and others. Bauxite, a natural hydiatsd {
alumina, the same material as used in the Hall aluminum process, is flsl> |
cined to drive off the water and then fed into an electric fumaee. the
struction of which is shown in the illustration. It oonasts of
Fio. 12. Carborundum Fumaee.
sheet>iron shell moimted on a hydraulically operated plunder that
and lowers it, to maintain a constant current of 2.000 ktmperes at 80 voila
The electrodes consist of two carbon rods that project into the shell, wfai^
is cooled by water, from the U-shaped trough, trickling down its outer
surface.
The time consumed for fusion is about 12 hours. The mass is allowed to
cool and is then removed from the fumaee by holding the sheet-iron d
in position and lowering the plimger, the product bang broken qp i
sorted. It consists of four parts: namely, a red and blue mass in the ^
tenor, crystals that form in the blow holes, a porous outer portion and a
by-product consisting of a metallic regulus of ferro-siKoon which is used for
the treatment of iron in the Bessemer and open-hearth fumaeea Tie
porous outer part is used as a recharge, and the mass as well as the erystHi
which are of the general nature of rubies and sapphires, in fact fhenilesir
identical with these gems, are ground up and used to make grindinc wfasob
and other abrasives.
Cyanides of PoUusitan and Sodium are produoed electrocbwnVafr of
the process of C. S. Bradley, C. B. Jacobs and others. ^ A mixture of hsttea
oxide or carbonate with carbon is heated in an electric fumaee to inediae
barium carbide (BaC^). While the mass is still hot, nitrogen (air etsnet
be used, as the oxygen present would oxidise the barium and carbon) si
passed through it and barium cyanide forms, the complete reaction tMBg*
BaO + 3C + Na - BaC.N, + CO.
The barium cyanide thus produced is treated with sodium carbonate, the
result being a mixture of^ sodium cyanide and barium carbonate. The
former is sqMirated by dissolving it in water, the insoluble p— •£— >
carbonate being used over again. Potassium oyamde is made in a
ELECTROTHERMAL CHEMISTRY. 1247
manner and either nit is suitable for gold eztraction and other purpoeee
for which cyanidee are employed.
Sl«ctrlc SaielttB|r* — One of the earliest oommereial proceesee in eleo-
troehemistry was that devieed by £. H. and A. H. Cowlee in 1884. A mix-
ture of about 2 parts of alumina, 1 or 2 parts of granulated copper and
1 or 2 parts of carbon was introduced in a brickwork chamber. Bundles of
carbon rods inserted at the ends formed the electrodes between which a
current of 3000 amperes at 50 volts was maintained. At a very high
temperature the alumina was reduced (Al«Qs -f 8C — Als + 3GO) and the
resulting aluminum combined with the copper to form aluminum bronse.
'Tbim process is no longer of commercial importance, since pure aluminum
enn be readily purchased; and when smelted with pure copper gives a better
grade of alununum bronse at a lower cost than is poasible with the above
method.
Iron and sissi can be produced by reducing iron ore with carbon In
an electric furnace. For example, a mixture of magnetite and carbon can
be heated by iwnmng a current through it aa in the Gowles aluminum bronse
process; through a carbon core in contact with the material as in the car-
WKUodum proeess; or by the action of an arc as in the carbide process.
The reaction is Fe«0« + 4C - 3Fe + 4CO. Pure {i.e., wrought) iron,
esut iron or steel may be produced, depending upon the proportion of car-
bon. The chief advantages are the directness ot the process and the fact
that the impurities in the fuel (sulphur, siKoon, etc.) are not introduced.
On the other hand, it is a question whether the electric furnace can com-
pete in eeonomy with the blast furnace and Bessemer converter.
The field which is at present being developed is the conversion of scrap
ircn and pig iron into crucible steel by means of the electric furnace. This
method offers reasonable chance of success, since the cost of crucible ste^
is hish and therefore tiie method empk>ved may be relatively costly.
There are several distinctive types of furnaces employed, some being of
the nre type, some of the resistance type, and another of the induction
type. This latter method seems to be the most promising, since the poe-
nmlity of introduoing anode impurities into the charge is abeohitely done
away with.
X-RAT8.
RaviBBD BT EIdwabd Ltmdom.
The oKimAto nature of X-fays is m rnuoh a matter of doabC at lb
{TMent day as .when Profeator Roantcen prcaentad his oriciaal pap«ik
895. It ia geaerallv eonoeded that they are the product of eathode ni«
these latter havinc their origin in electrical diecharves through high vaeoa
X-ra^ are produced whenever cathode rays etrike aome solid miimtaam,
and the method employed for their production oonaiets in «»ffsiting a "
tube, having electrodes sealed in its ends, by means of a atauc '
or from the secondary of a hi^ potential induetion ooil.
Under the influence of a high potential dark or cathode rmym
from the negative terminal or cathode; these rays are repelled from ih
surface of the cathode, and where they impinge on a solid oabetanee X-n^
are emitted.
X-rays and cathode rays are fundamentally different in that the eathsdi
rays are subject to magnetic deflection, whue X-rays are not. lliii iMi
is explained on the assumption that the cathode stream eonaists of partida
movmg at high velocity and carrying a negative chaige. Sueh a stnas
is capable of being deflected by a magnetic field. When, however, theoatliDde
stream strikes the solid substanoe, called the anti-cathode, the pvtiMi
yield up their electric charge, and in passing from this point as X-nyi
show no magnetic deflection.
The discharge of the cathode stream does not neeessarily take pM
within the tube from terminal to terminal, but may be made to tzaTel n
any desired direction by altering the positkm and configuration of tte
cathode.
The generally accepted idea is that these rays travel in lines nonasl to
the surface from which they originate, and for tlus reason the eathode nay
be so shaped that the rays can be focused on the anti-cathode; that csthod"
rays can be focused is well known, but William RolHns huolds thst it v
doubtful if the rays actually travel in lines normal to the cathode soriMe.
reasoning that since the cathode stream is made up of moving partiek*
carrying a negative charge there muat exist a repelling force Letwsen sB
such particles; if this repelling force did not exist, the path of travd wooia
be normal to the cathode surface, and the focus point would be foond st
the colter of curvature of the cathode. Rollins states that the foeoi poiB^
Ues beyond the center of curvature of the cathode and that this dwsMt
between the actual focus and the center of curvature increasss iritk V"
creasing potential across the tube terminals, due to an inoreased (^sif*
and consequent increased repelling force between tlM particles eoostitiltill
the cathode stream.
Where cathode rays strike upon glass or a like substanoe, the phsoomesosf
of fluorescence appears. These rays are similar In n^my respects to X-iV^
both are able to excite fluorescence, to affect sensitive films, and are av*
ject to selective absorption in paswinn through solid substances.
The fact that reflection and refraction have not been conclusively cw^
by experiment to be properties of X-rays would indicate that these m*
are not in the order of transverse vibrations. .
Quite recently, however, experiments have been made in whieb 'i **!
shown that X-rays are subject to polarisation, and while r^ectioBiw
refraction have not been absolutely proven to be properties of ^1^ JH^
the generally accepted idea is that X-rays are ether vibrations of eoonso*
frequency and short wave IsnjKth. These rays, like ultra violet li^t^J^
discharge electrified bodies. Tnis fact maybe accounted for on thsmrtg*
theory of X-rays, on the assumption that when the changed partidei vs»i
up the cathode stream strike the anti-cathode they yiekl up thsir ^eeuv
charge and pass from this point as X-rays, to all purposes a ^^^^i^
moving* particles divested of their electric charge; these puticles woan *^
tend to become charged again in the presence of an c3eetnfied body< <*
1248
X-BATS.
1249
ia iBora pnbablei howevw, that X-rays are etlur Yibmtioiia, and that dii-
;e oi •leotrined bodies uoder their influeaoe is due to ionisatioii of tha
_ similw in this respeet to ultim Tiolei UghU
VHl»«a. — Tubes lor tha production of X-mys are made of class, the
electrodes are sealed in the tube and the air esEhausted, and upon the decrev
of vncuum d«>ends the penetration of the X-rays emitted*
It is desirable, and the genenl pmctiee, to provide some metallic bod^
in the tube upon which to focus the cathode rays, this being the anti-
cathode, and it is from this body that X-rays are emitted. In Fig. 1, A
is the anode, B the anti-cathode, and C the cathode. The relative positions
of these terminals may vary considerably with the different types, but in.
all cases the functions are the same.
A separate electrode in the tube acting as the anti-cathode is not essen-
tial in the production of X-rays; as they are emitted whenever the cathode
rays strike any solid substance^ they would appear. if the cathode rays
were focused on the glass tube itself, or the cathode rays may be focused
ao as to fall on the anode, making this single electrode both anode and anti-
cathode.
The anode and cathode are usually made of aluminum, as this metal
undergoes very little disintegratioA undv the action of discharge. Owing
Fio. 1.
to the difference in the expansion coefficients of glass and aluminum it ill
neceoaary to join the anode and cathode to platinum wires, sealing the
platinum into the glass in order to make the external connections.
Where the cathode rays strike upon. a comparatively small area on the
anti-cathode considerable heat is develpped, consequently some metal,)
such- as platinum, which is capable of withstanding high temperatucs*
must be used for the anti-cathode.
Under normal operating conditions tha anode and the anti-cathode are
oonhected to the positive of the source of supply, while the cathode b, of
course, connected to the negative. Considerable care should be exereued
in keeping the direction of current flow through the tube in the rii^t direo-
tion, for u the direction of current be reversod and continued for a length
of time, blackening of the tube will result because of the disinteBration of
the platinum anti-cathode, and the tube becomes inoperative. The direo*
tion of the current flow, per ss, through the tube has nothii^ to do with
the production of X-rays, but it is essential that the cathode stream shouki
travel in such a direction at all times so as to strike the anti-cathode.
The tube shown in Fig. 1 would emit X-rays if the e?ceUing source were
ao alternfttlng current of sufficiently high potential, but X-rays available
for use, i.e., those sent out from the anti-o^tbode, would be emitted only
half the tiioae, or during that time in which the cum^nt would be Jiormal
in directk>n, wlule the tube would be subject to a certam amount of ''
1280
X-BATS.
during tbon portioiii of time in which the oumiit flcwvd ia Um
Tubes hare been made for lue with
whioh is ahown in Fie. 3. In the tube shown both terminnti are ao
as to foouB the cathode raya from each terminal durinc the half eyeb ii
which it ia a cathode, upon a common anti-cathode.
The penetration of X-raye ia dependent upon the vaeuum in which th^
originate, while the emiaaiTity of the anti-cathode increaaee mm the atoaot
weueht of the aubstance fomung it increases.
Suioe the penetmtive power of the raya ia in a measine proportional ts
the decree of Taouum, several tubes of various decrees of ezhanstioB sn
necessary where the class of work is varied, and in all case* tubes sh
be selected for the particular use for which they are intended; bat
having a vacuum, the resistance of which is equivalent to a six or ~
inch spark gap, will give fairly good reaults for a variety of work.
Fie. 2.
A. W. Isenthal and H. Snowden Ward state that "there eadeta a condi-
tion, the causes for which have not yet beoi sufficiently studied, when toe
tube emits rays of great penetration and withal s^elds a Ttgorous imait^
both on the fluorescent screen and on the plate. The characteris^i^o>
this stage of maximum efficiency are an incandescent anti-cathode m
some traces of blue anode light in the tube. Unfortunately this stats of
affairs is more or less transient, and the tube soon becomes fierforated.*
The vacuum gradually increases with the amount of use of tubes, tw
being ascribed to the fact that the anti-cathode and other ptatinum larti
withtn the tube are subject to slow disintegration under the action or St
charge, and the particles so separated, on cooling, oodude some of vi
reeidual gas in the tube.
If the Increased vacuum is due to the occlusion of the residual gM o^
viously the original vacuum may be partially restored by the appficatitna
heat, the occluded gas being stYen up under the action of heat.
This heat may be supplied oy some external source or by sending tlsiMP
the tube a current of sufficient strength to appreciably warm it, ins foBiV
method being preferable.
In all cases it is advisable to include a spark sap in the dreiiit to thstsBa
It lessens the liability of the tube to puncture m case one of the eletjirw*
becomes detached, and it acts as a gauge on the vacuum. diec^aiBe tatias
place across the gap if the vacuum and the consequent resistance of the i^am
mirease apprecwbly.
X-BATS.
1251
•— It Is impoflsible to pfewnt gradual
^ — in yaouum. and resulting ohangw in rewwtanee and penetrative
power of the rays with eontinued use of a tube, but these ehanjices from the
oricpnal state may be minimised by the use of Regeneratire Tubes, many
types of which are on the market.
There are certain substances, such as palladium, etc, which ooolude gas a*
ordinary temperatures and yield up tnis occluded gas on being heated;
•dymntage is taken of this property for maintaining the Tacuum. One
type of regenerative tube is shown in Fig. 3.
Fio. 3.
The absorbent is placed in a branch of the tube, shown at il ; an auxiliary
path for the current is provided through this branch, but under normal
conditions no current passes via this auxiliary path. If, however, the
vacuum increases beyond a predetermined spark length for which the ad-
justable arm B is set. the current will then travel by way of the auxiliary
path in preference to the path through the tube, with the result that the
eathode rayi from the auxiliary catnode in the abeorbent chamber will
heat the absorbent, causing it to give up its gas which lowers the vacuum
in the tube. This gas, bawever, is reabsorbed when the tube cools.
Another method of regeneration depends upon the fact that at hish
temperatures i^latinum is permeable to hydrogen. Fig. 4 shows a tube
in which a platinum wire is sealed into the side neck of the tube at A and is
protected by a glass cap. When the resistance of the tube increases a^
preeiably the glass cap protecting the wire is removed, and as the latter is
heated b:^ means of a Bunsen Burner or a spirit hanp, hydrogen is in-
troduced mto the tube, lowering the vacuum.
'^tr^^
Fie. 4.
The tube shown in Fig. 4 has an anti-eaithode designed to obviate high
temperatures at this point. This anti-cathode consists of a heavy metallic
bean with an oblique reflecting surface, the head forming part of a metallic
tube which extends back into the comparatively cool side neck, this metallic
tube being connected to the outside terminal By means of a wire. Due to
the fact that the head and metallic tube have considerable mass and are
good conductors of heat, exposing a large surface for radiation, the heating
of the reflseting surface is not excessive.
1252
X-RATS.
Vftrioui forma of anti-«ftthod«8 have bean deviied to obviate hif^ IM^
peratuTM. jKeneraUy taking the form of water eooliac (not in direct ooatMl)^
or by ao oispoains metallic bodies that the heat seneraied at the ttButim
•urfaoe will be rapidly eoodvoted away.
Mxcitinr ftomrco. — The minimum potential acroee the tcrauaali oft
iracuum tube for the pioduotion of XHraye has been variously tefliMfwrt fam
7000 to 100,000 volte. The appearance of X-rays, howem, under • p»
sure of 7000 volts was due to special conditions, and, ordinarily,
much hiffher must be emplovcd.
Hich potentials could, of course, be obtained from apeeially
transformers working on altematins current circuits, but since dosbk
focus tubes, adapted for altematins current, present oiffionlties in srlal
operation, their use has not become general, and other aouroes of kiib
potential giving a uni-direotional current are almost universally used.
Static machines give very good results, their current beinc uni^direetioH
and the potential practically constant, and therefore a steady disehsip •
produced through tubes excited from these machineai
They are simple, and since they dispense with batteriee and indsrtioi
coils have much to reoonunend themj unfortunately, however, they behiti
in the most erratic fashion, the polantv being subject to rer ' ^*^ '
rotation of the disks is discontinued, this, of course, beins
^ The most general method empk>yed for excitation is by induction wk
giving high potentials at the terminals of the secondary winding.
The induosd current in the secondary winding is not, however, uni-din^
tional, but alternating in character. The wave form of the aecoodirT
current, while alternating, is not uniform, i.e., the induced E.M J*, duets
rupturing the current in the primary circuit greatly exceeds the indnen
E.M.F. produced by closing the primary circuit, or. m other words, the ia-
duced S.M.F. at break is greater than E.li.F. of nwke.
Fig. 5 shows the manner in which the current in the primary drcei
varies.
ul
oe
3
O
nut
Fio. 6.
Because of the inductance of the coil, the eurrent doee not iminidlijjj
reach its maximum value, but increases logarithmically as indicated urv*
portion of the curve marked "closed/* j^a.
The inclination of the curve, or the rapidity with which it n*^*'?
maximum, will vary with the constants of the cireuit for each partieohiren
but Fig. 6 shows the general form of the current carve. The is|»w
with which the current changes in a circuit is proportional to the tuss*^
stent of the circuit or L/R, in which L is the self4nduction and R w !«■""
anoe of the circuit.
falls
When the circuit is ruptured, however, the time within which thsw^
Us to sero, depending upon the ratio ot the inductance (L) and i «■■■■"
X-BAYS.
1253
CM) of the drenlt, is erectly diminiahed beoauM R \b incrmaed enonnoualy,
mm to opening tne otf euit. The ratio L/J2, and oonaequently the time in
•whieh the current falb to sero, ia very amall aa compared with the oorre-
■ponding valuea on doains the eircvdt.
Since the induced E.M.r. in the aecondary eircoit ia proportional to the
note of chanif0 of magnetic linea through the tuma of the aecondary coil, it ia
evident that the inauoed E.M.F. of brealc will greatly exceed that of make,
mm the current of the primary circuit changea very much more rapidly in the
former caae than in toe latter.
Usually the E.M.F. due to cloaing the primary circuit ia not of auffieient
intenAty to excite the tube, ao, for thia purpoae, the current from the seo-
ondaiT of an induction coil may be conaidereid aa uni-direetional.
Mmierrmtera* — Interrupters for opening and cloaing the primary
csircnit ahould have the following charaeteriatica: (1) Uniformity of inter-
ruption, (2) high frequeney, and (8) completeneea of interruption. With
re^Met to vequenoy of interruption there are Hmitationa impoeed by the
propertiee of the iron oore, and the diapoaition and number of tuma of wire
eon^poaing the ooil.
Suioe the primary eorrent does not inatantly reaeh Ita maximum value
vrben the circuit ia cloaed. a certain time muat be allowed for thia increase.
If the apeed of interrupter be auoh that the circuit ia opened before the
eurrent haa reached ita maximum value, the full capabilitiea of the ooU are
not used. Thia eondition is ahown in Fig. 6, and the eurvea ahown therein
are for current in the primary with respect to time.
ui
TIME
Flo. (I.
In the flgore, the frequeney of the interrupter ia aoeh that the circuit
remaina cloaed only through the time interval indicated by the letter C,
durin|[ which time the primary current haa reached only a rnXuB ahown by
the heiijpht of the ordinate at the inatant of interruption.
A coil operating with an interrupter having too high a frequeney may
have ita efFectiveneaa increaaed if the E.M.Fr impreaaed on the primary
circuit be increaaed, thereby forcing the primary current to a higher value
in the aame time interval; on the other hand, the effectiveneaa may be
increaaed under certain oonditiona by increasing the time of make and
reducing the time of break, the frequency of the intemiptw and the applied
S.1I.F. remaining the aame.
There are two general typea of interruptera, via., meohanical and eleotro-
lytie. Many forma of meohanical tntemipten have been deviaed and
varioua designs are on the market in which provisions have been made for
varying the frequeney of interruption and the latio of time of make and
Itia
tialinaU
that the actual breaking of the eurrent ahould
1254 X-BAT8.
b* >i nnrlr (utantanwua M powlble, Mid to tUi and tba qwrfc
batman tha bnakuiB lurfusH or polnti muat b» •stlncuUied.
inifnnfn B[iutiDC usroi ' — '
■Md by sonBMtinc k oo
"1. inumiptar. while la a
' vk b bbwn out ' -
Tbaaleiitnilyllo (.. ...
la ■faown in iti liinpkat bmn in Fie- 1-
•ikd eoodaU.ot two deotrodes of wldtf
dlotmtlnf proportiiiiu. mefa a* > phU«<M
nasdle pmiit ud k Iukb Bbsat of lead, b-
uunad In * nlutiaii of diluti
Mid. The plUiaum oeedle poi
diued Into (b« daetnlyM throurt k d*"
tub*, the pluinmB bou MkMiMotki
tSam. H thet ■ nry hibU an« — !■■>■■■
cally > point — i> in di)«ct eontact
tba electmlvta. It tb*K t*D deeti
be goDDMtM thraoch an tudnetaDcc
■oume of mpply. the ooiTeDt In the a.
will be MbiMit to twdar and impid katr-
niptionL The plaUBum p^nt deetnili
■hooM b*«onn«t«d to tb* poaitiv- ' -"-
^^■paadot tbietypeof iatorw.- .
decnand by inmaiiBc the mrtmol ik
— ^ poritivs eleotroda. other oonditione n
n..lnin- tb« nine, whllt ioireaBiic ih.
Flo. 7. appllea E.1I.F. inoreaHa the freqiKBrr
aM tba Burrent in the eireuit.
Fla. S, ibowi complete diasram ot sonoeetkina (or an X-ny owii ■
which an alectroIytlB btoruplw la mada lu ' ' '
beinc a itorace batteiy.
.lytlofi
Mta
FLUORESCOPE8. 1255
The phenomenon of fluoreeoenoe is the emiMion of visible light when X-
rays or eathode rays strike certain substances.
In transforming the energy of X-rays into Ught for the examination of
radiosoopic images some substance must be useowhioh fluoresces under the
sw^ion of the rays. Roentgen originally used barium platino-oyanide, and
this 18 very largely used now, although various other substances, such as
potaaeium platino-oyanide and calcium tungstate, are in use.
^noe the amount of light given out by a fluorescent screen is* small, it is
necessary to exclude all other forms of light either by carrying out the ob-
atf"vations in a dark room or by enclosing the screen m some suitable obser-
wation chamber having an opening for the eyes.
The chemtcaJs used m preparin|( the fluorescent screen are applied to some
support, this support in turn beuig fastened in the observation chamber.
Various supports for the chemicals, such as cardboard, vellum, blackened
on one side, and rubber, have all been more or less used.
ELBOTBIO HBATING. COOKINQ AND
WBLDINQ.
RavisBD BT Max Lokwbntbai<, E. E.
For definitions of Heat, Uniis, Joule's Law, etc., eto., see paces 3 audi
** Electrical Engineering Units.*'
VaHowi Methoda of Vtlllsiac <k« Hes^t
bj tlie Klectric CurreMt.
1. metallic CoMd acton (Uninterrupted Circuit).
1. Exposed coils of wire or strips.
Ca) Entirely surrounded by air.
(b) Wound around insulating material.
2. Wire or strips of metal imbedded in enamel.
(a) In the form of coils. ) Leonard, Simplex, General Ekm^
(b) In flat layers. ) Crompton, and othen.
3. Wire or strins of metal imbedded in asbestos and other insolatiBg
materisJs.
(a) In the form of coils.
(b) In flat layers.
4. Wire imbedded in various insulating oompounds.
(a) Crystallised acetate of sodium, etc. Tommael.
5. A Film of metal.
(a) Rare metal fired on enamel. Iprometlieae.
c6j Rare metal fired on mica. I ^rrrm.
(e) Silver deposited on fl^ass. Reed.
6. Sticks of metal.
(a) Crystallised silicon in tubes of i^ass. Le Roy.
(6) Metallic powder mixed with day and oompresaed. Funm-
7. Metal in the form <^ powder or granules.
(a) Kryptol.
8. Incandescent filaments in vacuum.
(a) High wattage, low efficiency lamps. Dowsiiigi Gsntfsi
Electric.
II. Heat of tfeio Cloctric Arc (Interrupted Circuit).
1. The electric furnace. Siemens, Cowles, Parker, and othefs.
2. Heat of arc acting upon material, producing local fcais-
Meritens, Werdemann, Bemardos, Howells, and othen.
3. Welding by bringing metals in contact. Thomson.
4. D^ecUng are by magnet. Za«ner.
III. Hydro-elocti^tbonnlc Ajatoas, or ITator-maa V«fff*>
Burton, Hoho and Lagrange.
Referring to the above classification. Seetion I, the methods nfensd to
under subheads 1 and 3 require no further eyplanation. Tlie method vaa/t
1266
L
1
KI.BOTSIG HBATINOi COOKING AND WELDING. 1267
■abh^ad 2 oonsisto in imbeddinc the ranatanoe wire in aome firmioof inau-
lation aueh as enmmel or slaoa. This insulAtion is of oomparativeiy poor
quality as a oonduetor of heat, and so thin that it affords the least possible
teaistance to the flow of heat from the heated resistance.
The Maiplex ftyetctat {Carpenttr Patenia, subhead 2), employs high resist-
anoe wire imbedded in an enamel, oonsistinc of two parts, the ground mass
and the surface. The former oonsbts of siuoa. erystallised borax (for flux-
inc), fluoispar and magnesium carbonate, nuxed in various proportions,
powdered and fused. 1^ this is added aluminum silicate and i>ure powdered
quarts. The enamel nroper consists of flint meal, also tin oxide, saltpetre,
ammonia carbonate^ lead sulphate^ magnesium sulphate, potassium ear-
boxukte. borax, and sometimes crpsum and arsenic. These are carefully
mixed, as too much of any insreoient will make the enamel crack off, or will
make the f udon point too hiffa or too low. The insulation resistance varies
from 40 megohms when cold to 1000 ohms at 400** C. Most enamels melt at
about 900*" C.
The CtoMeral Kl«etric quarts enamel type unit (subhead 2), consists of
spirals of "Climax" resistanoe wire deotricaUy insulated from the surface to
be heated by quarts enamel. The quarts grains are used as an exodlent
binder for the enamel.
The «fe««nU Slectric oartridge type unit (subhead 8), consists of a
Gennan silver wire flattened into a nbbon and wound edgewise in a spiml.
To insulate betwem the turns of this spiral it is dipped in abath of insulating
eement. The mass is then squeesed together, so that a thickness of inso-
latin|( material of .003 inch remains between the turns. The spiral, forming
a sohd cartridge, is sHpped into a brass or German silver aheUL with only jDI
inch of mica between the edges of the ribbon and the shell. The heat, pass-
ing through the thin thickness of mica is conducted to the outer shell and
thence by direct contact to the surface to be heated.
ThePMasatkene 0jsitanB (subhead 5) employs units composed of striiM
of mica about .004 inch thick, on which is painted a thin film of gold or plati-
num, sometimes only .001 mm. thick. The metala, in the fonn of powders,
are mixed with a flux and then painted on the mica, after which the whole is
subjected to a higdb temperature, the finished films sometimes having a resist-
ance of 100,000 ohms, each being made to consume not more than 70 watts,
this giving a temperature of about 460° C. To prevent injury to the film it
is eoverea with another^strip of mica, and then tonthcr are pctrtly enclosed in
of these strips varies from 60
a thin metal frame. The insulation resistance of these strips
to 300 megohms, and the increase in the resistance of the foil varies from 10
to 20 per cent during a period varying from 1 to 8 minutes.
The Raeci method of depositing a layer d silver on glass was described
in the Bleetrieal World, June 5. 1895.
The method employed by Iieltay (subhead 6) consists of enctosingstioks
of crystallised carbon, having a spedne resistance 1883 as high as that of
ordinary arc light carbon, in daas tubes. For 1 10 volts, rods are 100 mm. long,
10 mm. wide, and 3 mm. thick. This takes about 150 watts; and having
a surface of 28 sq. cm., the dissipation of heat is at the rate of about 5 kg-
calories per sq. cm. of surface, or an absorption of electrical energy of 6 watts
persq. cm. of surface.
PiBrvll1« {VBeUnrage Elec., Jan. 28, 1890) uses rods of metallic powder,
mixed with fusible day (quarts, kaolin), compressed under a pressure of 2000
kg. per sq. cm., and baked at a temperature of 1350^ C. A rod 5 cm. k>ng.
1 em. wide, 03 cm. thick, has a resutance of 100 ohms, and absorbs 16500
watts per kg. One quart of water boils in 5 minutes with 15 amp. and 110
▼dts.^
Kryptal (subhead 7) ia a patented German substance, consisting of a
mixtuxe of graphite, carborundum, silicate and clay in a granular form. A
bed of this refractory material has an electrode of carbon at each end. The
siie of Enrptol granules varies accordinjs to the voltage. The current is de-
tetmiQed by the thickness of the bed. Temperatures up to 8600° F. may be
obtained. Durini^ a teat made by H. Allen, a cube of copper weighing 8.45
grains was melted m one minute, the pressure being 240 volts and tne current
15 amperes.
The above methods are u^ised in the construction of electric cooking and
heating apparatus, while those enumerated under Sections II and 111 are
emploTsd for purposes of welding, smelting, and forging.
1268 ELECTKIC UEATlNd,
AND WKLDlHa.
iiiii
i sl|| i
a si
|i liii^i
-ma
111
-l»
5 .
iiil
85
-5 #51
» " i
si 1 1
IN
11
:f
it'-
m
i|
BLBOTRIC COOKI^O.
1259
Omi* ef M^pmriKtim^ Blectrle Co^ktey VtoMilU.
On MMOuni of the number of varUbleB which enter into the determination
of tlie cxwt of electric heating and cooking, it is impowible to present any
Benaral data. These variables may be cUasified as toUoifs:
1 . Cost of current. 2. The skiU of the operator from the oooldng stand-
point. 3. The skill of the operator from the standpoint of using the eleo-
trical apparatus economically. 4. The type of apparatus emplosred.
It ie possible, however, by assuming an arbitrary oost for current^ to
oaloulate the oost of heating a given quantity of water. Let it be re^uuned
to heat one gallon of water at a temperature of 50^ F. (10^ C), without
AOtuaily boiling it, to the boiling-point, or lOO** C: it would then be elevated
gO^ C. Hence 3786 cubic centimeters would be raised 00^ C. or 3786 X fiO -
840,740 water-gramme-degrees-centigrade of heat are produced. The unit
corresponding to a water^gramme-oegree-centigrade is the calorie, which
requires an expenditure of 4.18 joules, so that the work required to be done
in miaing a gallon of water to the temperature of 100<> C. is equal to 340,740
X 4.18 — 1,424,293 joules. Assuming the oost of electric current, in large
Quantities, to be 5 cents per kilowatt-hour (which is equal to 3,600.000
joules, as 1 joule — 1 watt per second), the cost of raising one gallon of water
to the boiling-point is approximately 2 cents. If we assume the eurrant to
cost 15 cents per kilowatt-hour, then the coet would be 6 cents.
This calculation, however, is strictlsr theoretical, as the assumption is
made that all the heat generated is utilised in raising the temperature of
the water. This, of course, is not the case^ as a certain amount of Uie heat is
transmitted to the metal vessel and the air during the time of the operation
(about 15 minutes). Assuming the efficiency of the vessel to be 70 per cent,
which represents the ratio between the useful and the total developed heat,
then the actual cost of heating a gallon of water from 10^ to lOtr C. at a
cost for current of 5 cents per Kilowatt-hour would be 2 X W ~ 2.86 centi^
or at 10 cents per kilowatt-hour would be 2 X 2.86 — 5.72 cents.
An approximate rale (aooording to Roger WilHams) for estimating the
aoMHint of energy required to raise the temperature of a quantity of water in a
given time, by means of an eleetricallv heated pot is:
One- third watt will raise one pint of water 1' F. in one hour, or 3(X) watte
will raise one pint of water from 70*" F to 212^ F in ten minutes.
0«st •€ Heatinc Water te IMflTerent TeMpenita
Jambs I. Atbr.
Initial temperature of water, 60^ F. Efficiency of apparatus, 85%.
Total
Temp.
D«.F.
One Pint Watts Used for
0)st in Cents with Current at
5 m.
10 m.
20 m.
1 Hour
3 0.
5 c.
10 0.
20 c.
100
164
82
41.04
13.68
.041
.068
.136
.272
160
372
186
03
31
.093
.155
.31
.62
175
468
234
117
39
.117
.195
.39
.78
200
576
288
144
48
.144
.24
.48
.96
212
624
312
156
52
.156
.26
.52
1.04
One Quart.
100
324
162
81
27
.08
.136
.272
.544
150
744
372
186
62
.186
.31
.62
1.24
175
036
468
234
78
.234
.39
.78
1.56
200
1.152
576
288
96
.288
.48
.96
1.92
212
1.248
624
One
312
Gallon.
104
.312
.52
1.04
2.08
100
1.206
648
324
108
.32
.544
1.088
2.17
150
2,076
1.488
744
248
.74
1.24
2.48
4.96
175
3,744
1.872
936
312
.94
1.56
3.12
6.24
200
4,608
2,304
1.152
384
1.15
1.92
3.84
7.68
212
4.902
2.402
1.248
416
1.26 2.08
4.16
8.32
1260 ELEOTBIG HRATIKG, COOKIKQ AND WELDIKO.
Aooordinc to Mr. Grompton, th« afl&oiflacy of «a oidinaxy
using solid fuel is only about 2 per cent, 12 per cent beins wmated in
IDC a slowing fire, 70 per oent going up the chimney, and 16 per eeait
radiated into the room.
In a gas-stove, considering that the number of heat units obtainBible tmm
the gas at a oertun price is but small compared with solid fuel, the vesti-
lating current required for the operation alone coneomes at least 80 par ecst
of the heat units obtained by burning the gas.
In the case of an deetrioaloven, more than 90 per cent of the heat cBSxr
can be utiUied: and thus, althouipi possibly 5 to 6 per cent only of the hmt
energy of the fuel is present in the electrical energy. 90 per oent of tiuB, or
4h per oent of the whole energy, actually goes into the food, and thos thi
eleetrioal oven is practically twice as economical as any other oveBi, whetiMr
heated by solid fuel or by ges.
210
ilISO
CO
w _^
WHO
s
giao
90
00
^
y
^
,, J
^
T
«
IB La
MtKUT
oewAJ
ncNo
. OF^
It B
TTS
ATOr
t40«—
MO.
aai
-«
/
•ttf\.t I
AVCIU
/
1
I i
i
(
i
1 1
0 1
%
MINUTES
Fig. 1.
G^nopanatlTe
Report of Heating CommiUee, Auoeiation of Bdieon Illuminating
CompaniM, September, 1905.
The comparative operating cost of electric and gas cooking depeods apoe
two questions, — the relative rates for gas and electric heat units, aad tat
relative heat efficiencies of gas and electric apparatus. A third quantity 7-
the effect produced by the different rates and modes of heat applicatkioi »
the two classes of utensils — may effect the efficiency sUghtly, but the eiiil-
ence of this effect is not yet venfied.
Starting with the heat of coal, which may be fairly estimated aa W^
B.T.U. per pound, we compute the relative effidency of the heal eon' ^
as follows:
Gab.
1 pound coal produces 6 cubic feet cas.
5 cubic feet gas contain 3000 B.T.U.
Efficiency heat conversion is
3000 ft. .
j^;^ - 26 per cent.
EiAcnucrrr.
1 pound coal produees 0.25 K-V*
0.25 K.W. contains 853 B.T.U.
Effidency heat oonvenioo is
853
12000"" '**P*
Efficiency Electrical Heat Conversion ^ ^ .
Efficiency Gas Heat Conversion
RLBCTBIG COOKING.
init. but with prasmt proemnu the ralmtiva ntiB u
I. I El^CTHlOITT.
*1 .00 Mr 1,000 oabie faet.
I B.T.O. .000187 oeaU.
1 B.T.U
;2--17.S.
Eltetrto B.T.q. 0.00293
Qu B.T.U. 0.000107 "
It is known that th* •SdaDny of eleetiieml sppuktiu (a sbout tout Iham
tlut of n«, ltd. DonHquently. as the BW utouil nquirn four times u muur
B.T.U., th* kbova fifun of 17.6 it redund to 4.4. If. thun. the ntn for
riMtrioityignduced tAonv-iiiuTtwaf thatuaiiinBd.or3.SceiiUpBrK.W.H,
this fifrura of 4.4 it duugM to 1,1. and m mvt pnctioally idmiad
Cpart
VH.pti
imulJba
Aynr (nport foi
1,000 effective h ,
iqutnd44.0S5 K.W.K.
Natlooa] ElMtrte Liibt Assoeia-
n effidsDcv of Hmitv oer mt
' ""u. be Sd*
(17 oenla per K.W.
n eanta per K.W.
The above ia ai fair a comi
nnnot wbU be noured. The
.000 01
nan be made when euet fiaun*
ova qaotad have been oheeked bv
itely iMinc pa and elactricity aaoh
I lu B iiuuiiier of caawi, and from a vanat* of
It is lUHUioed that suitable equipmenta Goth
C«a« ar OyentttBC Klf^trlBkllr I
(
1263 ELECTBIG HEATING, GOOKIXfl A.ND WEU>lNa-
'flaina
H
i s
I i
i
SSI
lililli
¥i¥PW
M s J < 1 '?!
I*
:iii
mini I
t0i
■"a Is - ■
II « I ^ £ Ji J
Is'
353S ais
nil le
iiir
■is? 3
ll
■LBGTKIC UKA.TIKQ. 1263
■IscMc Xr*u tor DmaeMIc MmM KariautrlBl ^Mp ■«■]«.
Th« advuiUga dI alHtria Irona over ironi h«Uil by M «>«'• <x othir
by AtimiDAting; Che travel betweea iron And Bouroe of heat. ODUAWttrMkni of
b»t. so Umt the iroa onl)' ^ni not the n»m ia bniiUE hwwd. Impravid nn-
1tBT7 ooDditioni and practicaUy uaifonn tfimperatun ttf iron face. In view
of * number td tbna advautagn. it bas been found io actual praotlM tiiat an
aTeiuv lamily of Gva psnona. where the ooUani and oufCs an Mot out to b«
lionad, oonaumea about 13 . 2 kilamit hours per month for ironlnc. whtoh
at the 10 oeot nt* per K.W.U. amounts to tl .32 per month, whioh li about
Uie aftnw ai it fM werg uaed. SDetini $1 . 00 per 1 .000 oubio f*M. The tatt
at operatioD variea with nie of Iroa. Forordftuiry domeeHc re
4t»ii pound ^
wfaether of the awitoh in the handle w reaiatanoa in the atand tj
Watia
.. ._ .sot regulator, the iron most eominonly uaed . .__
about six pouada ancTooDauiaiiis about SOO w*tu per hour. The reKulatois,
— ■ — ' ■■- ■■-'■ - -'- '--ndle or reaiatanoe in the atand type, effeot %
nt. The po««t oooaumptioo of Om rariona
4 ponod* Troy Potlaliiii& diamond taoe
81 pounda SniiaO Baaming (can be «>
4 poiuida Oentleman'a Small Hat ti
hi poondi Ucfat Domeetie
S| pouDda Uiht Domeatia,
(can be eooDMtad to lamp soeket) .
SI pounda Horoooo Bottom
Iforoooo Bottom, round nofle ,
C*aaM«i«lal Slectirlc tjmmmikvj ■qalpBteat.
(Ai Bthltman 4 Crait Campanu, Philadelphia, Pa.)
T-5 pounda Sad Irona each 3 . 2fi Amp. at 1 10
! Body Ironera . . . '. each 41.50 Amp. at 110
2-12 Inch Sleeve Ironen e>ah 12.40 Amp. »t 110
1 Collar and Cuff Ironer each fl .50 Amp. at 110
3 Boaom Ironen euh IS. 80 Amp. at 110
1 Rotary Collar Bd«er each 2.90 Amp. at 110
1-7 pound Sad Iron each 23.00 Amp. at S4
2-7 pound Sad Iron eaoh 24.00 Amp. at 24
I Cottar Bdginilfadiine «ch e.26Amp.at SO
1 Helm Collar Bhaper each 5. SO Amp. at 20
Total Equipment 23.1
A foil dSHiriptJon of " A Blodel Eleolrieally Opentted Laundry,"
Kitowlton may be found in the July. IBOS. uaue of TAt BUetrical i
York.
■LBCTRIG ^n AVISO.
Unleaa eleotrieity la produeed at a very low oo(t. it ta n
prmodeable to heat reaidencee or lanre buildings- While u._ ... ...... »«.
nxrma. oold oomera of rooma. street railway waiting rooms, the summer vilta
on ODol eveoiiw, and in mild olimfttee aatin wider range. It hae thepeauliar
advanlafB t>\ bang instantly available, and tbs amount of heat ia reaulatad
St will. The haatara are pofectly dean, do not vitiate the atmosphen, and
ST* portabla.
{PromMitat Ettetrie Company at Enabrnd.)
The heating ^ rooma and buildinga oan be aooompliahed dther by mdlmnt
« oonreoleirheBt. Wiik tht former method healing ta dIeatM by tb*
t&mw flf glow lamps, and with the lattar by iiislalsiiiiaa w — "-^ — ' -* — ^ -
pukUValy low la '
1264 BLBOTBIC HEATIKQ, GOOKINa AND WKLDING.
In the jlow lamp type the fiUments of the Uinpe are raised to an t iwil
inidy him temperature, and the electric «Qergy u tranalormed mainlr * —
ndiant neat, only a small portion beins given off by oonduotion aai
veotion — h«ioe the name * radiator.'*
In the non-luminous tsrpe the resistances are either bare or embedded is
enamel and raised to a oomparativel;y low temperature, which heats the am
in contact with them, thereby setting up convection currents in the sir.
They are generally designated as radiators, though the term is a znisn
They should rather be named "convectors or air warmers.'* The dxffc
between these two methods of heating is a very wide one. The best m
to employ depends entirely on the nature of the work for which the hi
are required, as explained below.
Keailisr by Haillatlom. — The heat from glow lamp radaton
has been likened to sunshine. The analogy is excellent and has no di^bft
induced many non-technical people to universally emi>loy this type of kesi-
ing in preference to any other, regardless of the nature of the work ii hinli
they desire it to perform.
It is very necessary in deciding which type of heater will ^v« the BOit
satisfactory results; to know the purpose for which it is to be used, and the
conditions under which it will work.
Radiant heat only raises the temperature of a body which is odhisb
to beat waves; it passes through the air without heating it in Uie sh^tSBU
and only causes a rise of temperature in the air by heatmg any «>bjects tbs<
offer opposition to its passage through them, these in turn heating the sir is
contact with them by conduction.
Heat waves are unaffected by air currents and the glow lamp radiator i^
therefore, suitable for warming oneself by out of doors, in baloonies, euu. or
for quicluy warming any portion of one s body. Hie li^t emitted is shs
oonsiderea by some people to add greatly to the attractiveness of the beatsr.
The heat nya are reflected forward b;^ means of highly jx>l^ed refleeton
placed at the back of the lamps, and strike against any objects in their path.
The sone of action is dependent on the shape of the reflectois, which for
constructional reasons are made in simple shapes, confining the heating fidd
to a small area.
The temperature to which the i^ow lamp radiators will raise aznr opaqjot
body when placed in any definite position rdatave to the lampe iscfependssft
on the density of the heat rays on the surface on which they faU, from which
no doubt has arisen the popular fallacy that a rsdiator, in front of wlii^ it
is uncomfortable to hold one's hands, must be emitting more heat than s
oonvector, in front of which they may be kept for any length of time without
any sense of discomfort. The only true measure of the rate at whi<^ heat ii
bang developed by two different heaters working under exactly i«»«n»r eoa-
ditions is the amount of air heated per unit of tmie multiplied by the toa-
perature throu^ which it is raised. Thus a heater constructed to work at
a very low temperature may be giving out far more heat than one worldaK
at a nifdi temperature, though the former would appear to be the more
powerfiU of the two if gauged merely by the sepsation produoed on putttsg
one*s hands close to the flames.
Air warming by radiant heat is an indirect method by which unifonni^
of temperature throui^out a room or buUding can never be attsdned. It
h of the utmost importance that the temperature be uniform, as freedosi
from draughts and consequent comfort and healthy conditionB cannot othet^
wise be secured.
Heisilair by CoavectloM* — The heat generated in the lesistaBea
warms the body of the conveotor, and the air is heated by direct contact with
the hot surfaces. Convection currents are oonsequenUy set «ip in the ncii^
boring air, whio^ quickly equalises the temperature throui^out the rooa
in which the conveotor is placed. This method of beating dwelling noma
is, therefore, under normal conditions, far more efficient than that of rsd»>
tion, provided the temperature of the resistance material is not hifl^ eoom^
to materially affect the humidity of the air. Oonveetors are not, however,
in virtue of the comparatively low temperature at which the^ wcMrfc, so
efficient as radiators for quickly wanning one's hands or any portion of ons^i
body, neither can tiiey compete with raaSators when very stronc air catrsBfii
are present, or for open air work such as balconies, band stands, ete.
It hss been ssserted that convectors do not, like radiators, aooomplirii
useful work as soon as they are switched in. Sucdi broad statemttits srs
^
BLECTRIC GAB HKATINO. 1266
vi twsed on facts as the relative rate of air heating by a radiator or convec-
tiOT, absorbing the same power, depends entirely on their capacity for heat.
Maturally a convector with a heavy east iron frame will absorb a large quan-
tity of heat befors it can work at its maximum effidenoy, but all the heat
fthat is storsd in the frame is, of course, taken up by the air after the convector
%m switched off; sueh convector^ therefore, are suitable only for continuous
"work over long periods.
Kaevify Oo»a«flip«i«a of Electilc Heaten.
Aeoording to Houston and Kennelly, one joule of work expended in
producing heat will raise the temperature of a cubic foot of air about i^* F.
The amount of power required for electrically heating a room depends
aaem,tly upon the amount of glass surface in the room, as well as upon the
araughts and admission of cold
draughts and admission of cold air.
An empirical rule, commonly employed, is to figure from 1^ to 2 watts
per cubic foot of space to be heated.
According to an European authority if a sittinjp-room with a content of
100 cubic metera is to be heated to 17^ C, while the temperature of the
outside is 3^ C, he estimates that 3.500 kilogram calories are required per
bour; with electric heating this means a consumption of 4 kilowatt-hours
for every hour, while with coal fuel, about 3 kilograms of coal are required
per hour. Exx)erience has shown, says Uie same authority, that for every
degree OentipErade difference between the lowest outside temperature and
the desired inside t«nperature and for every cubic meter of space to be
heated 1 to 1.6 watts of electric power ara required; as an ^proximate
average 1 . 2 watts may be assumed. For instance, if the outside temperature
is 10° C. below, and a sitting-room of 50 cubic meters is to be heated to 18° C,
the difference of temperaturo is 28° C. Hence, 1,680 to 1,800 watts are
required, while the time in which the desired temperature is obtained varies
from one to three hours, varying of course, according to whether the neigh-
boring rooms are heated or not.
Contparlaoa l»etwo«a Bloctrlc aad Coal Hoattaf.
A kilowatt-hour in heat is about 3,600 B.T.U., and costs a consumer in
our lane cities from 5 to 20 cents according to the conditions, or from 72,000
to 18,000 thermal units per dollar. On the other hand a short ton of ordi-
nary good steam coal wul contain 28,000,000 of B.T.U. and allowing a loss
of 26 per cent in a boiler wall and flue, some 21,000,000 of heat units can be
looked for in boiler water, such coal costing from one to three dollars per ton
according to ctreumstances, and representing a sridd of 21.000,000 to 7.-
000,000 of thermal units per dollar, or in the neighborhood of three hundred
times more heat than the electric method wouloxurnish. The comparison
is in a certain sense unjust, seeing that the retail price of electric energy on
a small scale is compared with manufacturing cost of f ud alone for heating
water on a large scale, and a far better relative showing could be made where
both methods were compared from dther the manufacturer's or the pur-
chaser's standpoint, whatever the scale of production might be. {BdUorial
BUttneal Wand and Engineer.)
BliKCTRIC GAlft HKATIir«.
At the Hbntreal meeting of the American Street Railway Association in
1806, Mr. J. F. McElroy read an exhaustive paper on the subject of car-
heating, from which the following abstracts are taken:
In practice it is found that 20,000 B.T.U. are necessary to heat an 18 to
20 foot car in sero weather. When the outside temperature is 12^° F.
only 16,000 B.T.U. are required, etc, which shows the necessity of having
electric heaters adjustable.
The amolmt of neat neceseary in a car to maintain a ^ven inside tem-
rature depends on: 1. The amount of artificial heat which is given to it.
The number of passengers carried. The average person is cMsable of
giving out an amount of heat in 24 hours which is equal to 191 B.T.U.
This is evidently an error, as Kent says that a person gives out about 400
heat units per hour; and tests by the Bureau of Standards show the same
(413) for a person at rest, and about twice that for a man at hard labor (836)*
1266 KLKCTBIC HKATIMO, COOKING ADD WKLPtNQ.
The foUowtna teble VM eoranllad bT Ur. HeXlmj frcia the nsb n
-■--' •—m Iha AlbKi J RUlnT Oompunj :
fnel ont OD Albany IoIIwht. »r unp. I
total «wt for fiwl, labor, olli, mats,
ATengf
OMto:
Itiel per hoar tor h«>tlu > at
Porttloiiof 8*lteb.
lat
M. «. «h. 1 m.
Amparaaqul.
S.M
t^
tM
aos
a*
tSffiWtSS^SaS: :
M
M
M
1:S
II
S
S
I rni«tii Cast P«r D*7 r*r BisTa*.
IS Itw. ol Boal at t4.W per ton |
Damping and nmoTtng eoal and a«fa«B. ooallng np
udkindlinK flraTliicludinK e«t of klDdSng,
Uld part of cIsuiIde cat
BamoTing itoTfla lor aaminer, Inalalllnf for vtD-
l«r, repairing li«ul lining*, repalnUng, sic,,
aTorage per dar
SLECTBIC CAB BBATINQ.
1267
»r l^lvlMT f«r '^C^i
for lJ«elU«iMr Vnus Plask
It
c^^
.^mwwxwwi^-
JMMMMMMIL
6-H««ter £quipm#ttt
=;irri"P
"'■ fi
-SMiB
l^s
Bten^
>!!»■ ir
3%:?:
I lit II.
l^«|j[««l«r £<iuipm«nt
«8»
■»•■
3SS4BB
^^
%
tii^m-
Truss Flank Heater in position, showins wiring in mouldinc.
Fig. 3.
1268 ELSCTRIC HEATING, COOKING AND WKU>ING.
iU
for ^€3mmmml
for CW9m
• 9
f
6-»U«^ier £<|uipBi«nt
II II It II It ii
H It II II II ,)l
Cro88 Seat '*OoiuoUdated" Heater in positioii.
Fio. 4.
SLBGTBIC CAB HBATINO. 1269
Aeoordins to a paper read by J. T. McElroy before the Street Railway
AasooiAtion of New York, on oar heating, about 10 to 20 per cent of the
wamrgy required for running is spent in the heaters, and the ayerage of tests
taken upon American cars with ooal and electric heaten for 15-1kour runs
■ave tike price per day of 16 hours for ooal as 9233, and for eleotrioity 92J20.
Poiatons to JP«rcliaaera mf Slectric Car lEettteiv*
(SiTMl Railwaif Jaunud, November 5. 1904.)
We think it only fair to the eleotrio heater to call attention to a very
oommoB fault on the part of companies purchasing electric car heating
equipments, which fault usually results in the end m a condemnation of
eleotrio heaters. This fault lies in trying to get along with a few heaters
worked at a hi^ temperature rather than a large number worked at a
lower temperature. The reason why companies attempt to do this is, of
oourae, to reduce the first cost of heater equipment. If a car is to be heated
■a ooinf ortably by electric heaters as by hot water, the nearer you can come
to distributing the heat evenly throuf^out the length of the car and avoiding
exoesaively hot points, the better will be the results. It is coming to be
more and more established, that heating of any kind can be done more
efficiently by a large radiating surf aoe worked at low temperature than by a
amali radiating surface worked at high temperature. Furthermore, working
eleotrio heaterB at low temperatures n oondludve to a long life, while working
at higkk temperature is not.
Isdoatrtol Blectrlo HeatlMf.
Among the industries to which electrically heated apparatus has been
successfully applied may be mentioned: Book binderies, printing shops,
hat factories, candy ana chocoUte manufactories, laundries, wood-working
establishments, shoe, paper box, glove, corset, dmtal goods factories, as
well as hotek, hospitals, restaurants, laboratories, bakeries, etc. In faot.
wherever gas or steam is being employed for the localised application of
heat, electricity has been found, in most cases, a more sanitary, flexible,
safer, cleaner, as well as equally economical source of heat.
nectrlc VLmmt Im Priattasr JBatelillalUBeBta. -— The moet ex-
tensiveL as well as most economical, neating equipment in a printing office,
is, no doubt, that at the Government Printing Office at Washington, D. C,
designed and installed by the Hadaway Electnc Heating Company.
The following pieces m apparatus are being eleotrioaUy operated suooesa-
fttUy at the present time (1007) in this office:
Matrix Drying Tables.
Wax Stripping Tables.
Wax MeltingKettles.
CSase Waraiing Oabinet.
Ghse Wanning Table.
Wax Knife, Gutting down Ifaohlne.
BnUding up Tool Heaters.
Sweating-on llaehines.
Soldering Iron Heaters.
Embcssing and Stamping Press Heads.
Qlue Heater Equipments.
GlueOookeiB.
Gms Making Ifaohines.
Book Cover Shaping Machines.
FfaiJshsn' Tool Heaters.
Pamphlet Covering Machines.
Sealing Wax Melteri.
Further details of this equipment have been published in the Washin^^a
Elsotrietl Handbook, issued in September, 1004, by the American Institute
of Electrical Engineers, and a senes of articles in the BUetrical WoHd and
BngiMtr. Vol. 43, pages 0-14, and succeeding issues.
tlbe ttsims made by the government representatives in favor of elee-
trically bested apparatus as compared with steam and gas, are as follows:
1270 BLEGTRIO HEATING, OOOKINO AKD WELDING.
tiaML
The absence of exoesB of heat that would be found in forms o>th<
electrical.
The ability to reduce the amount of tame neoesaary to make
The ability to bring the apparatus to a workiuK condition in 1<^
The fact that in eight years of operation they have not had an
a burnt-out coil.
■lectrieally Heated l^iric«a la tlie PrtattBr Sh^^p
P. r. Collier * Sea, New York.
The following list of apparatus is giv«i here in order to show
details of this Mass of apparatus as well as the developments of this
industry.
Apparatus.
2 glue pots .
23 glue pots
1 glue pot .
8 glue pots
2 glue pots .
2 wax heaters
6 press heads
1 press head
1 press head
1 press head
1 press head
1 press head
1 press head
Type and Sise.
Simplex 20 gal ,
Haoaway 1 qt
Simplex 1 qt
Haoaway 2 qt ,
2 gal
22 i'l. X 24 in. X 31 in.
22 in. X 24 in. X 31 in.
22 in. X 24 in. X 3} in.
22 in. X 24 in. X 31 in.
22 hi. X 24 in. X Sf in.
19 in. X 12 iu. X 31 in.
12 in. X 12 in. X 3} in.
Max.
Min.
Amp.
Amp-
100
22
2
.5
2.5
• ■ •
10
2.5
22.8
• • ■
100
40
35
2.8
36
4
36
3.6
36
3.5
86
4.5
30
2.5
25
2.5
Volts.! Wata
I
110
llO
110
110
220
110
llO
110
llO
110
110
110
110
5lOO
275
12.67J
22.000
I9.2S0
3.M0
3.300
2,730
lll,9g
Forty*nine artides.
Summary
eonsuming 112 Kilowatts.
Ill Press Heads.
36 Glue Pots.
2 Wax Heaters.
XiOboratory Use. — llie milk supply of New York City is Bovt
by tests made in the taboratory of the Board of Health, by means of electzis
stoves. Twenty-five 4-inch disc stoves, of 60 watts capacity, are used to
boil the ether used in the tests. Fourteen times per hour these little stoves
cause the ether to vaporize. The germ producer, measuring 22x22x22
inches, is heated to 130^ C, by means of electricity, a maximum current of
16 amperes being employed for 15 minutes every hour, while 3 amperes keep
up the desired tempMrature.
Coffee aad Cocoa Di^yera. — The cocoa and coffee trade hasappfied
dectric heat to its small desiccating or dnring cabinets. A dryer 31 feM by
5 feet, requiring a temperature ci 150 degrees, requires about 74 watts ptf
cubic foot when propeny jacketed. The oeans are particulariiy susoepaMs
to the odora arising from combustion, hence the advantage of eleetric heat.
For drying kilns 40 watts per cubic foot are recommendea.
Cfluadj' Maaafactare. — : Warming tables and chocolate dlppinc^^tols
have proved successful. Fifty watts produce sufficient heat to keep tke
ehooolate in working condition. A 30-gallon tank holding caramel paste ii
supplied with 10 kilowatt hours to keep the j;>aste at 285^ C. and eecn nMslt-
ins costs about 65 cents. The service is mtermittent, henee the adapta-
bility of electric heat.
- AoUlerlac aad Hraadlny Mroas. — The canning industry, as wiB
as the makers of switchboards, and others, find the electric soldering iros
a useful and economical tool. It has been found more economical to oper*
ate electric soldering irons heated by current costing 5 cents per kilowatt hoar
than irons heated in gas fumaces, with gas at $1.00 per 1000 cufaie fstt
Heaters of 110- watt capacity are niade. into which a soldering iron is thnati
thereby doing away with the connecting handle cord. One thousand hep
ger hour are stamped, "Inspeoted," by the government meat inspectors a
hicago, by means of a 40O>watt branding tool, which is an electric eolderini
iron with a die inserted in place of the copper tip.
SLBCTBIO WELDING AND FORGING.
1271
The following figures show the details of operation of a 44"oeU storage
lottery outfit, mounted on an automobile truck, in comparison with those
>btained by the use of a rheostat in series with a direct-current 3- wire Edison
lystam with the neutral wire grounded. The figures represent the average
unounta in each case.
Am-
peres.
K.W.
Hours.
Time,
Min.
Pipe.
Inch.
Volt-
age.
Cost
Revenue
per Case.
Storage battery
Btreet supply . .
513
275
1.39
10.4
5.44
19.0
1
81.5
120.0
$10.85
14.43
$16.40
16.93
The street supply is used until the season has so far advanced that the
number of cases will warrant the exclusive service of an automobile truck.
■liHCVMSG -WMM^nWBf^ AMD X^m«X9«.
The eurrent employed in electric welding may be theoretically either
continuous or altematmg, but on account of the difficulty of producing low
tension continuous currents, it is only practicable to employ alternating
eurrent. All eleotrie welding machines are fitted with an alternating cur-
rent transformer as an integ^ part of the machine.
1 Slectric WeldlBf 1
The jprindple involved in the system of electric welding, invented bv Prof.
Elihu Thomson, is that of causing currents of electricity to pass through
the abut^g ends of the pieces of metal which are to be welded, thereby
generating beat at the point of contact, which also becomes the point of
greatest resistance, while at the same time mechanical pressure is applied to
force the parts together. The passage of the current through the metal at
the point of junction, gradually but quickly brinfl^s the temperature of the
metal to a wdding point. Pressure follows up simultaneously, a weld being
effected at once.
K«n«i-Power Heed 1« Klectrlc WeldlaiT*
The power required for the different sises varies nearly as the cross sec-
tional area of the material at the joint where the weld is to be made.
Within certain limits, the greater the power, the shorter the time; and
vice versa.
The following tables are based upon actual experience in various works,
and from very careful electrical and mechanical tests made by reliable
experts. The time ^ven is that required for the application of the current
only, and may be shortened with a corresponding increase in the amount of
power applied.
d Iron or Ateel.
Diameter.
Area.
H.-P. Applied
Time in
to Dynamo.
Seconds.
iin.
.05
2.0
10
in.
.10
4.2
15
■
in.
.22
0.5
20
in.
.30
9.0
25
■
in.
.45
13.3
30
r
1272 ELBGTKIC HBATINGy COOKIKG AND WELDIKGb
▼y
Iniide
Diameter.
Area.
H.-P. applied
to Dynamo.
Time in
Seoonda.
lin.
fin.
1 in..
U in.
llin.
2 in.
2} in.
3 in.
.30
.40
.60
.79
1.10
1.66
2.26
3.00
8.9
10.6
16.4
22.0
32.3
42.0
63.7
96.2
33 .
40
47
63
70
8i
93
106
CI«Beral T»l»le.
Iron and Steel.
Copper.
1
Area in
Time in
H.-P. applied
Area in
Time in
H..P.app]i4
sq. in.
Seconds.
to Dynamos.
■q. in.
Seconds.
DynaaafM^
0.6
33
14.4
.126
8
lOJ
1.0
46
28.0
.26
11
SS.4
lA
66
30.4
.376
13
31J
2.0
66
48.6
JS
16
42jO
2JS
70
67.0
.626
18
61J
3.0
78
66.4
.76
21
6L1
3JS
66
73.7
.876
22
7^
4.0
90
83.8
1.0
93
83a
y round axle requires 26 Horse-power for 46 seconds.
1'' square "
(«
30
" 48
(«
ly round "
tt
36
" 00
It
ll^^sqtuu-e "
tt
40
•' 70
u
2^' round "
tt
76
♦• 96
M
2" square "
41
90
«* 100
<i
The slightlT increased time and power required for welding the squsrt
axle is not only due to the extra metal in it, but in part to the oare wmu U
is best to use to secure a perfect alignment.
Tire ITelilflBg.
tire requires 11 Horse-power for 16 seoonda.
>f II t« 28 ** ** ** 26 **
v li ti 23 ** ** ** 30 **
/ f« II 23 ** ** ** 40 **
'f tt «i 29 *» " " 66 "
•/ K tt 42 I* «♦ •• ^ »•
The time above given for welding is of ooune that required for the aekul
application of the current only, and does not include that eonaumed tr
piacins the axles or tires in the machine, the removal of the upset, tm
other finishing processes.
From the data thus submitted, the cost of welding can be readily flgsni
for any locality where the price of fuel and cost of labor are known.
^
KLECTBIC WBIiDOTQ AKD rORQIirO.
1273
A tost on the eleotrio w^ins equipment of the American Steel Frame
nd Band Iron Company of New York, made by the New York Ediaon
iDsniMuiy, to determine the amount of aiergy used per wdd, cave the
lUowins result. The equipment oonsists oi a SO horse^power 220 volt,
ireet current motor, belted to a 50 kilowatt 220 volt, 2 phase, 60 oyole,
iparately ezeited alternator, and three 7.5 kilowatt step-down tranafonn-
ns, with an approximate ratio of 45 to 1.
When welding iron frames .0352 square inch in cross section, it takes
kilowatt hour, supplied to the tranaronner, to make 600 welds, the time
nuired being 53 minutes. This averages 2 watt hours per weld, and
innc the time the current is applied as 0. 7 seconds pw weld, the weldfaig
■nent figures out about 2000 amperes at 4.75 volts. A meter installed
1 the motor circuit showed 4.2 kilowatt hours direct-current input for 390
«lds, making an average of 10.77 watt hours per weld.
Blectric Sail freldiar.
The ** Electric " Joint, applied by the Lorain Steel Oo., is made bv wdding
lates on both sides of the web of the rail. The plates shown in Fig. 0
n 1 inch by 3 inches, by 18 inches, and have three bosses, three welds
lAOtfAm 0fCOHH9KTI9H$ 9f HAIL fVCtOCII
S-TlB
ir.o*iitt0im
Fig. 5.
Web Platet
Fig. 6.
jMngmade at eaeh joint. Great pressure up to 35 tons Is maintained on
w joint whilst maldng and cooling. The welding current runs as high as
V,0iOO amperes. The connections are shown in Fig. 6.
1274 ELBCT&IC HEATING, COOKING AND WELDING.
Serener Bjuimmt,
In thig system an aro is used in combination with a magnet vbieh
the are, making a flame similar to that of a blow-pipe, bat baTiof tlw
peratnre of the aro. The apoaratns contains a self-regnlataf d
which is driven by a small eleotxio motor ; for welding bon a canesloC
00 amperes at 40 Tolts will suffice for strips of metal three mm. tblfik.
]l«imai^4M 0j-st»Ha.
In this system the article to be operated upon is madetoeoDstltiftasas
pole of the electric circuit, while a carbon pencil attacked to a yufffMs
Insulated holder, and held by the workman, constitutes the other pole, tta
electric arc — which is the neating agent of the process— bi^
between the two Doles thus formed. This system has been used ext
in England for the repair of machinery. The Barrbeat-Straage
Barrel Syndicate use tnis system for the welding of Che seams of
steel barrels.
Voltox yrocsw for W^eldlar •«« Brmal^r
Ck>nslBts in the use of an electric arc formed between two spedsl ^_
rods inclined to eaoh other at an angle of about 90^. Hie whole ansaM
can generally be held in one hand. With gas and ooke, gas eosaag i^
70 cents per 1000 cubic feet, it is claimed the complete cost o .
filling up a bicycle frame is 91.43, while with the Voltes proceast at t
per kilowatt hoar, it is only 46 cents.
fttoaasuio Pi-oceaa of IBlectrIc •■aelfti^
Consists of heating, in an arc furnace, briquettes eompoeed of iroa si%
carbon, and lime mMe into a paste with tar. The smelting proeesa oseM
in a blast furnace, the Iron being reduced, and the siUeeous matter of di
ore slagged off.
Asusealiac- of Aivsor JPlate.
The spot to be treated is brought to a temperature of about l«0^f>
The current used is equiTalent to 40,000 amperes per square ineh, a deasltf
which is only possible by the use of oooUBgby water cirealatiaa. Hi
operation generally takes seven minutes.
In this system an electrolytic bath is employed, Into which an eleeferis
current of considerable £ Jf.F. Is led, passing from the posltiTe pole viii^
forms the boundaries of the bath and presents a large surfaoe to the ets»>
trolyte and thence to the necative pole, oonsisting of the metal or oAff
material to be treated, and which is of relatiyely small dimensions.
Through the electrolytic action hydrogen is rapidly cTolred at the Mgr
tiTe pole and forms a gaseous enrelope around the pole : as the sm k
a rery poor conductor ox electricity, a large resistance is thus introoaeai
in the circuit, entirely surrounding tne ol^eot to be treated. TbeeaReatii
passing through this resistance deyelope thermal energy, and this is fle»
municated to the metal or other object which forms the negatlTe pole.
This system has been extenstyely used in England, and is daaolbsd ii
The Sleetrical fforld, I>ec. 7, 1886.
B«rtoM Klectric Vorye.
In a patent granted to George D. Burton on an electrolytic fom, tkt
portion to be heated is placed in a bath consisting of a solution of sal soda
or water, carbonate of soda, and borax. The tank is preferably madB ct
porcelain or fireclay. The anode plate has a contaet surface with Ai
liquid much greater than the area of contact of the article to be hesui
This plate is composed of leaa, copper, carbon, or other suitable coadistiif
_j||^terial.
FUSS D/LTA.
1276
To a lecture on "The Rating and Behavior of Fuse Wires," before the
.. I. E. Em in October, 1895, MesBts. Stine, Qaytes, and Freeman arrived at
IbO following conclusions:
1 . Covered fuses are more sensitive than open ones.
2. Fuse wire should be rated for its carrying capacity for the ordinary
lengths emplosred.
2(a). When fusing a circuit, the distance between the terminals should
be couideiea.
3. On important circuits, fuses should be frequently renewed.
4. The inertia of a fuse for high currents must be considered when
protecting special devices.
5. Fuses should be operated under normal conditions to ensure cer-
tainty of results.
6. Fuses up to five amperes should be at least 1} inches long, one-half
inch to be added for each increment of five amperes capacity.
7. Round fuse wire should not be employed in excess of 30 amperes
capacity. For hi^er currents flat ribbons exceeding four inchee
in length should be employed.
The following table shows the sises of fuse wire and the approximate
eurrent-catrying capacity oi each sise:
(Cha»e'8hawmtU Company, Boston.)
Carrying Capacity Standard
in Amperes. in In
Length
ohes.
•
Diameter in
Mils.
Feet per Pound.
J 1:
10
2.700
'
17
950
1 1^
■
20
670
1* 1
■
23
510
2 1
26
430
3 1
'
27
370
4 1
'
30
300
5 2
35
220
6 2
38
185
7 2
44
140
8 2
47
120
9 2
54
93
10 2
58
80
12 3
62
70
14 3
68
60
15 3
70
52
16 3
73
49
18 3
78
43
20 4
88
86
26 4
90
82
30 4
100
26
86 4
110
22
40 4
122
18
46 4
126
13
60 4
147
12.5
60 6
160
10.3
70 6
172
9.0
76 6
178
8.3
80 5
190
7.5
90 5
198
6.7
. 100 5
220
5.5
1276 BLBOTRIG HBATING, COOKING AND WKLDIKO.
lm«t»ll»tlmi ^f
(H. C. Cuahing, Jr.)
Endosed fuses of standard sises are now on the market and are
to link fusee. Where the link fuses are used they shoukl have i
faces of tips of harder metal, having perfect electrical oonnectkm
fusible pe^ of Uie strip.
The use of the hard metal tip is to a£Ford a strong mechanical
the screws, clamps, or other devices provided for holding the fa
They should be stamped with about 80 per cent of the maTim
they can carry ind^nitely, thus allowing about 25 per eenf
the fuse melts.
The following table shows the maximum break distance and the
of the nearest metal parts of opposite polarity for plain open link I
mounted on slate or marble bases for different voltages, and for
eurrents:
125
VOLTS
OR LF.8R.
Separation of
Nearest Metal.
Parts of Opposite
Polarity.
Minimum BnsL
DSstanoe.
10 amoeres or lees
finch
lineh
linch
•
f indi
1 IDCh
11— lOO ampefM ... ^ ... ,
101-^00 amneres
125 TO 250 VOLTS.
Fuse terminals should be stamped with the maker's name, inittak, w
some known trade-mark.
The lengths of fuses and distances between terminals are impcntant noDti
to be considered in the proi>er installation of these dleetrical "safety valvsa"
No fuse block should have its terminal screws nearer together than one indi
on 50 or 100 volt circuit, and one inch additional space shoukl always bt
allowed between terminals for every 100 volts In excess of this alkreaMa
For example:
200 volt circuits should have their fuse terminals 2 inches apart, 300 volli
3 inchcL and 500 volts 5 inches. This rule will prevent the Dunung cf tbi
terminau on all occasions of rupture from maximum ottrrent, and this eairtfl
means a "short circuit."
Sudoeed Vaaea. — The "Enclosed Fuse " or *' Cartridge Fnse^'
sists of a fusible strip or wire placed inside of a tubular holding
which is filled with porous or powdered insulating material thrcMxgfa
the fuse wire is suspended from end to end. The wire, tube and liliiRl
are made into one complete self-contained device with brass or oap^
terminals or ferrules at each end, the fuse wire being soldered to the insdi
of the ferrules. When an enclosed fuse "blows'* by exeeos euzrent. ^
gases resulting are taken up by the filling, the endoeive tendency is reooes
and flashing and arcing are eliminated. "D. f W.," "G. £./* ''Nosik"
and "Shawmut," enokwed fuses are approved by the National Elsctai
Code.
LIQHTNINa CONDUCTORS.
Vi«r«rB ooneemlng the proper f imotion and yalne of lightning rods, eon-
noton, arresters and all protectire deTiees have undergone oonsiderable
nodlfication daring the past ten years. There may be said to be fonr
•eriocls in the history of the derelopment of the lightning protector. The
iTst embraces the discoyery of the Identity of lightning with the disruptive
tisolisfcrge of electrical machines and Franklin's dear conception of the
Lnsil function of the rod as a conductor and the point as a dischaiger. The
eooiMi begins idth the experimental researches of Faraday and the minl»-
f-nre Ikouse some twelve feet high, which he built and lived in while testing
Sfte effects of external discharges. Maxwell's suggestion to the British
Isfloelation, in 1876, embodies a plan based upon Fanuiay's experiments, for
yrotectlng a building from the effects of lightning by surrounding It with a
iace of TOOB or stout wires. The third period begins with the experiments
)€ Herts upon the propagation of electro-magnet^ waves, and flncu its most
brilliant expositor in Dr. Oliver J. Lodge, of University College, Liverpool,
wrhom^ exi>erlments made plain the important part whldi the momentum
of &11 electric current plays, especially in discharges like those of the
II|(litiiing flash, and all ducharges that are of very high potential and oscilla-
tory in character. The fourth period is that of the present time, when
indiwidual flashes are studied : and protection entirely adequate for the
particular exposure is devised, based upon some knowledge of the electrlcid
enersy of the flash, and the impedance offered by appropriate ohoke coils
or other devlees. For example, under actual working eondltlonSf with
ordinary commercial voltages, effective protection to electrical machinery
eonneeted to external conductors may oe had with a few ohoke colls In
aeries with intervening arresters.
A, good idea of the growth of our knowledge of the nature and behavior
of the lightning flash may be obtained from the following publications :
• Pranklin's letters.
Sxperimental Researches. . . . Faraday.
Report of the Lightning Bod Conference, 1682.
lioage's " Llghtmng Conductors and Lightning Ouards,*' 1892.
•• Lightning and the Electricity of the Air?' . . . MoAdie and Henry,
C=
,%M miK •XJ'^Mna mmrs «r avw •
FIQ. 1 EFFECT OF THE ACTION OF LIGHTNING
UPON A ROD.
That a lightning rod is called upon to carry safely to earth the discharge
from a cloud was made plain by Franklin, and the effect of the passage of
the current very prettily shown in the melting of the rod and the point
(aigrette).
Here indeed was a clew to the measurement of the energy of the lightning
llswh. W. Kohlrausoh in 1890 estimated that a normal lightning discharge
would melt a copper conductor 6 mm square, with a mean resistance of 0.01
ohm in from .03 to .001 second. Koppe In 1886 from measurements of two
nsdls 4 mm in diameter fused by ligntning, determined the current to be
about 200 amperes and the voltage about 20,000 volts. The energy of the
flash, if the time be considered as 0.1 second, would be about 70,000 horse
power, or about 62,210 kilowatts.
Statistics show plainly that buildings with conductors when struck by
lightning suffer oomparatlvely little damage compared with those not pro-
Tmed with conductors. The same rod, however, cannot be expected to
serve equally well for every flash of lightning. There la great need of a
elasslflcation of discharges based less upon the appearance of the flash than
npoa its eleotrical eneigy. Dr. Oliver J. Lodge has made a beginning with
1277
1278 LIGHTKINO GOKDUCTOB8.
Ills Btndy of Bieady 9irain and impHlHv nuh dlsehame. *■ Tbm
of an ordinary flasn." says Lodge, ** can bo accounted for by the <fi
of a Terr small portion of a duu-ged cloud for an area of ten 7|m^
at the nelgbt of a mile would ^re a dtodiarge of over 2,000 fc
energy."
We must ffet clearly in our minds then the idea that the eloiMl, the
and the eartn constitute together a larse air condenser, and tiiaA wT
strain in the dielectric exceeds a tension of ^ gramme weight per
centimeter, there will be a dischaige probably of an oscillatory du
And as the electric strain varies, the character of the discharge will
Remember too that the air is constantly varying in donsltj, hmnidity av',
purity. We should therefore expect to find, and in fact do,
discharge from the feeble brush to the sudden and terriflo bi
experiments indicate that after the breaking-down of the air and the pflh
sage of the first spark or flash, subsequent discharsee are more easQji^'
complished ; and this is why a very brilliant flash of lightniB^ is oftsi
followed almost immediately by a number of similar flashes of diTninlrti>H
brightness. The heated or incandescent air we call lightning, and ttw fiHi -
of Racture of the dielectric can be photographed ; but the electrical wsvessr
oscillations in the ether are extremely rapid, and are beyond the liauts «f
the most rapid shutter and most rapid plate. Dr. Lodge has calealsUed Iks
rapidity of these oscillations to be several hundred thousand per eeoead.
Lodge has also demonstrated experimentally that the secondarr or indaeetf
electrical surgings in anv metallic train cannot be disregarded ; and, as is
the case of the Hotel de ViUe at Brussels which was most elaboniiij
Krotected by a network, these surgings may spark at points, and Igsite
iflammable material close by.
While therefore it cannot be said that any known systeoi of rods, «ir«^
or points aiforda complete and absolute protection, it can be said with coa*
fldence that we now understand why '* spitting-ofl '* and " aide" dSaehaigai
occur ; and furthermore, to quote the words of Lord Kelvin, tiiat ** then if
a very comfortable degree of security . . . when li^tning oondoeton sit
made according to the present and orthodox rules."
AelecTtlon and Xaatiallatlon of Koda.~The old belief that %
copper rod an inch in diameter could carry safely any flatsh of liglitai^ii
perhaps true, but we now know that the core of such a rod would Save Ittth
to do In carrying such a current as a lightning flash, or, for that flaatter,saj
high frequencv currents. Therefore, since it is a matter of snrfaoe area
rather than of cubic contents, and a problem of Inductance rather than of
simple conductivity, tape or cable made of twisted small wires can be ased
to advantage and at a diminished expense.
All bams and exposed buildings should have lightnina rods with tJU ntea^
sary points and earth connections. Ordinary dwelling-nouses in eitybloda
well built up have less need for lightning conductors. Scattered or isolated
houses in the country, and especially If on hillsides, should have rods. AB
protective trains, including terminals, rods, and earth conneetlons, shoiid
be tested occasionally by an experienced electrician, and the total T«sisl*
ance of every hundred feet of conductor should not greatly exoeed one (riua.
Use a good iron or copper conductor. If copper, the oonduetor shoaM
weigh about six ounces per linear foot ; if iron, tne weight shoald be ab^
two pounds per foot. A sheet of copper, a sheet of iron, or a tin roof, tf
without breaks, and fully connected by well soldered lointa, can be ntiUsd
to advantage.
a ^ 6
FIG. 2 AND 3 APPBOVeO C0NDMCT0R8 AKD FASTENUfiaft.
PKBSONAX SAPBTY DU&ING THUirBBB-flTOBMS. 1279
lily published • set of Bnlet for the Protection of BnlldlngB from
^tiiliifir* issued by the Blectro-Technioal Society of Benin, Dr. SUby oives
ft rosmu of the work of Tarions committees for the past sixteen yean
idylns this anestion. The lightnins conductor is dirlded into three parts,
fcao terminal points or collectors, t&e rodor conductor proper attached to
ft building, and the earth plates or ground. All projecting metdillo sur-
mm abouid be connected with the conductors, which, if made of iron,
MUd lutre a eroes section of not less than 60 mm square (14) sq. inches) :
Kr, Sbbout half of these dimensions, sine about one and a half, and
.bout three times these dimensions. All fastenings must be secure and
ffetng. The bestground which can be had is none too sood for the light*
wg conductor. For many flashes an ordinary nound win suffice, but there
U ooBie occasional flashes when even the smiSl resistance of Xohm may
Bnt. JBury the euth plates in damp earth or running water. The plates
ould be of metal at least three feet square.
'* If tbe conductor at any part of the course goes near water or gas mains,
la beat to connect it to them. Wherever one metal ramification ap-
Oftebea another, conneot them metallically. The neighborhood of small
ire f oaible gas pipes, and Indoor gas pipes in general, should be aYoided.^*
BS. IjOPOX.
>•
Fia 4 CONDUCTORS AND FA8TENIN08*
(mOM AHSmON, AMD UqHTNlNa ROO OONEERiNCC.)
Hie top of the rod and all projecting terminal points should be plated, or
otherwise protected from corrosion and rust.
Independent grounds are preferable to water and gas mains. Olusters of
Mrints or groups of two or three along the ridge rod are good. Chain or
inked conductors should not be used.
It is not true that the area protected by any one rod has a radius equal
o twice the height of the conductor. BuildlngB are sometimes, for reasons
rhioh we understand, damaged within this area. All connections should
M of clean well-scraped surfaces properly soldered. A few wrappinss of
rtre around a dirty water or gas pipe does not make a good ground. It is
K>t necessary to insulate the conductor from the building.
, H. W. Spang gives the following estimate of increase of property destruo-
km by lightning from the "Chronicle Fire Tables."
Property loss.
$ 8.879,746
11,316,414
21.767,186
During five years
No. of fires
2.606
1807
6.687
1002
16,766
* SlectnteehnUcKe ZHUchrift, 1901, May 28.
r
1280 LIGHTNING CONDUCTOBS.
Much of this inoKMe in property Iom ia laid to be due to tJiecmt
in the um of wire fences in the suburban districts, also to the thUt
oreased use of metal work inside of houses, such as metal lath, ncsoi i
water pipee, and all metal trimmings now used so much in exterior ism
mings. Eleotric wires and their containJM tubes also attract Mfhtaisf;l|
fact, all the metal work now used in mooem building construetioo mirm
te attract lightning and convey it to the ground or store it up li in • mm
denser, which, upon being released, is liable to cause a qiark ud turn i^
fire to adpaoent inflammable material.
It is saxl that grounded arresters as now employed in power etsiioBf ■
connection with outdoor overhead electrical conductors also invite liH*
ning discharges, which, if they take place in the interior of boiUinnsis
liable to cause fire loss; and therefore, it is inadvisable to boateniek V'
ning arresters adjacent to wood-work or other inflammable materisL Um
electric signs on the roofs of buildings also serve to attract fishtolBp, iii
being connected with the interior electrical wires, sometimes jeopardnetlf .
safety of the buildings. Electrical wires in the upper stories of osr M
buikungs are said to become highly electrified during a thooder rtona, jk-
Hghtning from these is liable to impair any underground eleotrieal M'.
ductor connected therewith. _^
Overhead network wires such as those used for electric fight, likinM
telegraph and fire alarm, also attract lightning, and the dSchsigee sg>
these wires seem to increase in proportion to the number of gnxsaa
lightning arresters connected th«?ewith — so much so. that it ti ao*g^
mon to diBi>ense with the lightning arresters in fire alarm boxe^VIM
lead sheathings of underground circuits or conductors of all an"?
metallically connected with the track rails and return circuit of street *
ways, lightning is also liable to be attrad;ed, and discharges from it m tm
cases cause considerable damage. It is also said that the ^romniBI *
secondary transformer distributing systems at their neutral pomte^tf*
resulted in lightning discharges to the impairment of lighting trsnwMa^
Mr. Spang suggests that rather than connect overhead orcuita dgew
with grounded liffntning arresters or to connect return circoits of rairsg
with other metalBo networks that are grounded, there should be empnyB
an overhead parallel wire, which shall be thoroughly conneetsd to eiitt
at intervals, and which should preferably be kxakteoT at the side of sny o«^
head electrical circuit and parallel thereto; but experienced eogineen ^
have made a thorough study of protection from lightnu«, diow thit ui
parallel conductor does not materially ben^t the oonditions.
From the Underwriters' standpoint, ther^ore, the foUowkv ndei i*
suggested as necessary for protection of buildings from UghtniJis:
17 The employment of suitable metallic conductors about the n4g
chimneys or other ordinary elevations above the roof, in connection wok
all metal work about the roof and also with all exterior and interior ibcw
work, pipes, etc., all metallically connected together so as to provide noor
ous vertical metallic paths from the roof to the cellar and ther^y eooftt*
tute with the underground water, gas and other metal pipes, a dimp
ssnstemof metallic conductors about the roof and building ana over tbeMn
2. The shunting of the gas meters by suitable wires or otlwr am-
oonduotors.
3. The employment of two vertical iron or copper condueton tM
opposite sides of a church spire or a high chimney between a metsl caj-
weather vane or othw suitable air terminal conductor upon the top ths*
and the metallic conductors upon the roof, whidi are metalKflsUr j*^
nected with the underground water, gas and other metal pipes or <ff^
suitable ground connection. ^
4. A system of wires or conductors with suitable air twminab sboisV
roof of a bam, ice-house or storage warehouse and connected by ^'5'
four vertical conductors with ground connections distributed over s abhJ
area of adjacent earth, so that the atmospheric electricity will be diSMl
over a greater and better conducting area than that offered by tbe eo**
pactly stored hay. ice, etc. , .
5. The placing of lightning arresters or other grounded protaetioB d**
vices employed with electrical circuits about buildings in iron or BOB*eQ
bustible oozes, attached to brick, stone or other nonHX>mbustibb nsUM
or buildings and preferably upon the outside thereof.
.
^
CHIMKBY PROTECTIOK. 1281
CHumnsY piftOTEcraoH.
Vhe bnllders of chimnevB have made an exhaustlye study of lightning
tlon and have derelopeu a number of standard fittings for lightning rods.
M form of lightning-rod point is shovn in Fig. 6.
Flo. 6. Detail of Lightning-rod Point.
Usually four of these points are installed at the chimney top, oonneoted
Kether oy a band, and haying two or more conductors to the earth.
The United States Qoyemment has inyeetiflated thoroughly the require-
lents for chimneyprotection as sununariiedln the following pacagraphs:
1. CMasa«j JPr*S«ctloa for Powar Plasato. — Cightning oon-
■etors shall be laid up in the form of a seyen-etrand cable ana eaeh strand
kid up with seyen copper wires of No. 10 B. and S. gauge. For chimneys of
I feet and lees in height two lightning conductors shall be used. For
bimneys oyer 60 feet up to and including 100 feet, three conductors shall be
totalled. For chimneys higher than 100 feet, four conductors shall be
totalled. All heights to be considered from ground leyel. All conductors
r cables shall be symmetrically arranged about the chimney with one
Ible on the nreyailing weather side of the chimney. Said lightning con-
Snetoni or cables to be securely attached both mechanically and electrically
» Independent pure copper earth plates or bars. In cases where the chim-
Ity foundations haye already been filled in, instead of earth plates, earth
irminals may be used, composed of pure copper bars 3 by ^ inches by 3 feet,
ft all cases the lightning conductor terminals shall extend to the ground
rater leyel, and in no case shall they extend to less than 16 feet from the
round surface. Earth plates shall consist of pure copper 8 by 3 feet by |
leh.
3. .Jlpplicatloii of Coiidvcton to CklasMOT. — Each lightning
oodfactor shall be secured to the exterior of the dhlmney by means of
tonke or brass anchors, without the interyentlon of any insulators or insu-
lting material whateyer. The brackets for attaching ring or conductors to
hlmneys to be oil high grade bronze or brass, composition of same to be
nbmitted for approyal, and to be fitted with approved damps for seourely
ripping said conductors and making a good electrical connection there-
ith. The tongues or shanks of the anchors or brackets shall enter the
UMonry of the chimney a distance of at least 6 inches, and shall be at
MMti (nch in thickness by 1 inch wide, terminating In a suitable head or
Bgle to preyent the anchor from being pulled out of the masonry.
Lachors to be attached to conductors at intervals of not over 10 feet, and
sweated " to the conductors with solder at in tervals of 50 feet. Conductors
0 terminate within 6 feet of the top of the chimney, and to be connected
bfough the agency of a suitable brass or bronze fitting and be soldered to a
1 by I inch ring of copper attached to the periphery of the chimney by
rackets spaced not oyer 2 feet apart. Said brackets to enter the brlcic
rork a distance of at least 6 inches and to be of approved design with a
ongue at least 1^ inches in width and \ inch in thickness, with a suitable
agie or head to prevent pulling out. All joints in the continuity of said
(^per ring, as well as between the continuity of the ring and conductor or
onductors running down to the ground bars or plates and including the
itter, to be seraph bright and after makins a secure mechanical joint to
le ** sweated witn solder." Said solder shafl consist of one-half lead and
sie-half tin. All joints when finished shall be thoroughly washed off with
n^ to remoye every trace of soldering salts, acids, or other compounds
r
1282
LIOHTNIHO COKDUCTOR&
used. All joints Beonred by bolta or screws to be lock-nutted. In i
conductors where the chimney is already constructed, holes shall bs<
in the brick and said anchor brackets and anchors groined la, the
Portland cement being used.
3. VeraitBasl liada for MJfflUmimae C^akdactoiw.— OoMcri
shall be connected through the agency of clamps, insuring a goodsMl
ical and electrical joint, with Tertically arranged copper rods at lesttf '
in diameter and 10 feet in length. The joints to be " sweated with i
as before described. Copper rods to be placed equidistant around thk i
and supported in a rigid position Tertically through the agency of addit
anchors set in the masonry and a copper spider resting on enimiiejtapl
shown in the drawings, ftods to be arranged with a unifonu ipaei
practically 4 feet. This is taken to mean, for example, that tea
vertical rods shall be proyided for a chimney of 12 feet outside dlsadsr)
masonry at top.
4. ]»lacbaiv« P»tata. ~ Bach rod shall terminate in a twoiwiat 1
aigrette, each spur or point of this aigrette to be at least a| inehei
the bases of which spurs shall be at least | inch In diameter, tspsriafj
sharp and well finished point ; said aigrette to be provided with
means to secure a strong mechanical and electrical Joint with the ^
rods heretofore deecribed and to which it is attached. The Joints
** sweated with solder " as heretofore described.
5. ChMmummj JBsm« l^tmimvUmm. — AH lightning oondneton i
enclosed at bottom with a heavy galvaaised-iron pipe of li Inch "
and extending 8 feet into the soiland 10 feet above. Said iron
provided witn approved brackets to securely hold it to the
orackets to be not over S feet apart.
TMBTB OF I.K«HT1IX1V« MOIM.
All lightning rods should be tested for continuity and for
ground plate each year, and the total resistance of the whole oonlaeiai
ground plate should never exceed an ohm.
TESTS OF UGHTNING RODS.
FXO. 6. Diagram of Gonneetions for Test of Ltght&lng Bodfc
i
I80LAT£I> ELECTRIC PLANTS. 1283
iPClie oontinnity and resistanoe of the lightning rods above gronnd can be
Miwiired with a Wheatstone bridge. The reeistauce of the ground plate
r •earth can be determined from three resistance measurements ; from
kmnd plate to each of two other grounds and from one to the other of
lOve aroitrarily chosen grounds, as follows :
^o make the test, first determine the resistance of the lead wire li and call
Then connect £• and S^ as shown in the diagram, call the result Mi ;
maa. connect JSi and ^, call the result ^ ; connect E^ and £z *>id call the
malt Sz.
Now, J?t - /i + £i + ^ »nd ^ - J2, - it - -ffi
Ri^ In +Ei +£i and ^ <- i2a - li - J7|
solving, we have
El - 2 *i.
The resistance of the ground plate to earth Is J^i as calculated from the
bove formula.
VHVimMR ftXOlUU.
, I>o not stand under trees or near wire fences ; neither in the doorways of
■ma, close to cattle, near chimneys or fireplaces. Lightning does not, as
mle, kill. If a person has been struck do not give him up as beyond
iQovery, even if seemingly dead. Stimulate respiration and circulation as
est you can. Keep the body warm ; rub the limbs energetically, give
"afeer, wine, or warm coffee. Send for a physician.
FHB ■COirOBIY OF IflOXiATU^ KXiSCTlftlC JPIiAimi.
(By Isaac D. Parsons.)
The following investigation was undertaken by the writer and
tt". Arnold von Schrenk m an attempt to ascertain which of the two meth-
ds 18 the more economical m six classes of buildings in New York, and to
Mmune as nearly as possible those conditions, either inherent in a class
r buildings or due to peculiarities of installation or management which
latcriaJly influence tlw .economy. The six classes rrfenSd to are: —
iffiTO buddings, loft buddings, department stores, apartment houses.
1?^' .S*L®l'*'"U**^^ "X^'uf^^ hundred and fifty buUdings were visited
? the effort to, obtain reliable fisures and to ascertain the various condi-
»ns of operation. Of this number seventeen only were found where in-
ormation could be obtained which was reliable in every particular, and
«ly these will be considered in detail, as the great variation in conditions
▼en among similar buildings of the same class renders incomplete statis-
*«oi very doubtful value.
Tbe fif^ves as to electrical output of each of these plants were obtained
rom wattmeter readings or from hourly ammeter rradings. and were veri-
Sr-;2LiP*"I?'*** observation of the instruments from which they were
a>tained, and were also checked by comparison with other buildings where
omilar conditions exist. In some cases, tests were made of the instru-
nents to determine their accuracy. The figures recorded as the output
w A plant are m every case the total number of kilowatt hours suppKed
a the switchboard and used as light or power, and where a storage battery
was installed its output only was considered. The expenses of the plants
"we divided into those of labor, gas, central-station auxiliary or break-
lown service, cocU, water, ash cartage, oil and waste, repairs ineandsaeent
naps and are4amp carbons, intonest, depreciation, and sundry suppliaa
wt mdoded m the fpregomg. Figures concerning these items were ob-
eyed m most cases directly from the books of the chief engineer or owner,
MJ may be considered withm very smaU limits absolutely accurate. Under
ue Item labor wn mduded the wages of all the engineen, firemen, oilexs
1284 LIGHTKIK6 0Oin)UCTOSS.
and coal paflsers employed in the plant, excepting in a few cams
extra employees were required by a largfi refrigerating madiine or
apparatus. In these cases the wages of the extra moi woe
/rora the total. If it trere determined what employees oould be
with were the plant not installed, and the wages of these men onty
taken, it would give the true oost of labor chargeaUe against tbe ]
To decide this, however, was in most instances a rather nnoertaJB
difficult problem, and tt was thought fwrtf to include in the expeiee
wages of all the employees, which, with the other items, give the total
of running the building with a plant. Then, bv adding to the expeama
the central-station service the cost of the labor necessary for Intait
elevator supervision, etc., the total cost of running under the coadkMM
of central-station supply can be found. The difference between ibe tr
results is the true amoimt gained or lost by the installation of the pbsL
The item coal includes that which is burned to generate the stesa oi
for the engines driving the generators, for the feed pumps, and ^^^
cases that used for the house pump and whatever live steam is vmM
heating the building. In many buildings, refrigerating machinei, m
laundries, steam cooking apparatus, or pumps, received steam pvm
same boilers as the engines driving the dynamos; but in such iaar
figures from recent tests were available by which the amount of oosi
for these piu'poses oould be determined. ^^
Witn the central-station supply either a boiler or a cbnnection in!& V
street mains is required to obtain the steam necessary for heauv tii
building, as well as for the hot-water supply and for running tltel
pump, unless it is operated electrically. To determine what extn
must be added to the actual oost of current in order to find the total ^
pense of running the building from the central station, figures vera
tained from two lar^e loft buildings, an office bidlding, and six sjait
houses and hotels using steam for neating and for house pumps only,
which the oost of coal, labor, and water required for these purposes
be calculated. The expenses for coal were reduced to doUars per I
cubic feet heated, and showed practically constant factors, irrevti^
of the shape or siae of the building, of $1.10 per 1.000 cubic feet forffHr
ment houses, 00 cents per 1,000 cubic feet for office buildings, and ^^
per 1,000 cubic feet for loft buildings. The oost of labor, which iadnm
the wages of the firemen and the expense of elevator superviston. biit|
be determined in each particular case, but usually amounts to a sumsM
equal to the oost of oobX.
Interest was calculated in all cases at 5 per cent on the priocm^
vested in the plant. Depreciation on dynamos, engines, and switeolbatf*
of 6 uer cent, and on boilers, pumps, and steam piping of 8 per c«Dt. **
considered liberal; and since, as a rule, the oost of the dynamos, eogM
and switchboards approximates two-thirds of the total oost of iostaDstiA
and that of the boilers, pumps, and steam piping one-third, s nciaf*
rate of 10/3 + 8/3, or 6, per cent was charged against the whole pbnt. I
6 per cent of the original capital invested in the engines is set md9 a*
year as a sinking fund, this sum will accumulate interest at 5 per ^
and at the end of fourteen and one half years the total of the vstnot
reserved, with compound interest, will equal the original cost of the eogojK
so that 5 per cent depreciation assumes a life of but fourte«a sod obmp
years. Similarly 8 per cent depreciation on boilers assumes a Iif<i.<^2!
years. As a matter of fact, both of these periods are much exceeded ip "J
class modem installations. On storage batteries where deprerts^**
a somewhat doubtful quantity, it was taken as 10 per cent, which a9|a>>
a life of but seven years. The load factor in every case was caleulatcn^
the hours the plant was in actual operation.
As regards load and other conditions of operation, all the boildioff <*
be divided into two classes — -those used for business purposes, soo*
office and loft buildinfe and stores, and those which are used for rou^s^
purposes — such as hotels, apartment houses, and clubs. In the ksf^
olass a small uniform lighting load during most of the day ia socceMN »
about 3 P.M. by a heavy load lasting but a few hours, wbich after < r-J
again becomes very small. In the fatter class the heavy load, »n***^
falling off in the evening, continues to 1 or 2 ao*., giving a more uniWJ
load and a higher load factor. We will consider the business boildiiigS'^^
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FOUNDATIONS AND STRUCTURAL
MATERIALS.
RSYIBBD BT W. W. CHRISTia.
POWSA ftXAVIOir COMATlftlJOXXOir.
Cbart.
Bt E. p. Robsrts & Go.
r Foundation
Sta-
tion
Steam
Plant
BoUers
Link
En-
gines
(Setting
Stack
Fnel
Air
•■(•
Pli
'Source
Pumps and injectors, valves
and gauges
Heaters
Sediment
(Blow off
Mud drum
Steam pipe and
valve to heater
Entrained water,
separator
Pipins and valves
Covenngs
Drains and drips
Supports
'^Foundation
Steam
r Placing in building
J Placing in boiler
I Removal of coke and ashet
iRemoval of toot
.supply to surface
I Foundatioos
t Lubrication
Eleo-
trlcal
plant
Build-
. ing
Steam to cylinder
Oil to cvllnder
Steam from cylinder
Water from cylinder
Oil to engine
Oil from engine
Engine indicator
^ C Steam to condenser
-l Water to condenser
I, Water from condenser
r Belts
^Connecting links . . . -< Shafts
(^Pulleys
fFoundation
. I Lubrication
'Dynamos . . J Insulation
"^ Governing devices
Measuring devices
.Safety devices
r Dynamos to switchboard
Wire •< Switchboards to line
I Track to dynamo
Distribution devices
Dynamo governing devices
Dynamo measuring devices
Feeder to measuring devices
Safety devices
Gut-out and lightning arrester
''Weatherproof
Fireproof
Ventilated
Light
^Provisions for cranes or other strains foreign to its func-
tions as a shelter.
1289
Switchboard
1290 FOUNDATIONS AND STBUCTURAL MATSRIAIiS.
vevnvDATioBis.
The tonn f(mlkdai\al^ dMigiuttes the portion of a stmetiire
on which to erect the ■aperBtruoture, and most be ao eolid that ao
ment of the superstructure can takepiaee after its erectioii.
As all foundations or structures of ooarse masonry, wheCbar of
stone, will settle to some extent, and as nearly all soils are oam^
under heavy weight, care must he taken that the settlament ba
oyer the structure in order to avoid oraoks or other flaws. Altbomhtt
quite general to make the excavstion for all the sub-foondatiosi wnsrt
predetermining in more than a general way the nature of the 8tibsefi,Mf
then adapting the base of the foundation to the nature of soli found: yiril,
large undertaldngs, where there may be question as to the bearing, sodM
are made and samples brought up in order to determine the dlffereet stoit
and distance of rock below the surface. Where foundations are not tsis
deep, or the soil is of good quality, a trench or pit is often snnk alo
the location of the proposed foundation, and the quality of tbe aoil
mined in that way
The surface of rook should be cleaned and dressed, all deoayed .
removed, crevices flUed with gro^Mmg or f»^^, and where the
is inclined, it should be out into a series of level steps before conu
the structure. In such cases of irregular levels, aU mortar Joints mvlta
kept as close as possible, in onter to prevent unequal setUememi. AiA
better wav is to bring lUl swdi uneven surfaces to aoommon level vllks
good thick bed of concrete, which, if iiroperly made, will beoone as *
pressible as stone or brick.
The load on rock foundation should never exceed ane-elglith Its
load. Baker says " the safe bearing power of rock is certainly mol less
one-tenth of the ultimate crushing strength of cwtes. That is to say. A*
safe bearing power of solid rook is aof less than IS tons per aquare fsotir
the softest rook, and 180 for the strongest. It is safe to say that almost m
rock, from the hardness of granite to that of a soft erumbllag atoste «s0
worn by exposure to the weather or to running water, when well bedM
will bear the heavieat load that can be brought upon it by any imaiairr
oonatrnction." Bankine givea the average of onunary oaaea ae 9/P
pounds per square foot on rock foundations. Later in thia ^^^pMr- CP>i*
1322) wiu be found a table that gives the crushing load in pounds per sqsan
Inch for most of the substances used in foundations and building-waUs.
Strong grapel makes one of the best bottoms to build on; it la easily leselsd.
Is almost incompressible, and is not affected by exposure to the atmo^beffa
Sand confined to that it cannot escape forms an exeellent foandBtkm, sal
is nearly incompressible. It has no cohesion, and great eare must be end
in preparing it for a foundation. Surface water meat be kept ftom ruaataf
into earth foundation beds, and the beds themselves must be weU-dxaissI
and below frost-line. Baker says that a rather thick bed of sand or gnf^
well protected from running water, will safely bear a load of 8 to 10 toasiNi
square foot. Of course the area of the surface must be proportioned to m
weight of the superstructure, and to the bearing reaiatanee of the mataririi
gand for this reason it is common practice to spread the sabfonndatfas «•
ve it the proper area. Bankine glres 9,000 to 8,800 Ibe. per sqimre fool «
le greatest allowable preaanre on Arm eartha.
FM»«ailMi Mi CIsqr*
• A good stiff day makea a very good foundation bed, and vfll supiaCi
neat weight If care Is taken in its preparation. Water mnst be kent ssay
from It, and the foundation level must be below the froat-llne. As ka
day is exposed to the atmosphere the better wlU be the rssnlt. Bahtf
gves as safe bearing power for clay S/MWor 4/no pounds per square ML
audard says a stiff clay wiU support In safe^ ^jSOO to 11,000 poosdiyir
square foot.
FOUNDXTIOKS. 1291
OM Soft Bartk.
"WhiM the 6uih Is too soft to support the tupentmotore, the trench is
ifcTAted to a considerable width, and to a considerable depth below the
it^Une ; then a bed is prepared of stones* sand, or concrete, the latter
{ most in use to-day. In fact, it is a common thing to cover the whole
of the basement of large power stations with a heayy layer of concrete,
o£ * thickness suflioient to sustain not only the buUding-wallSi but all mik
iB^***^ foundations.
; S4Mnd makes a good foundation bed OTcr soft earth. If the earth is of a
tvsUity that will retain the sand in position. Sand may be rammed in
-inch layers in a soft earth trench, or it can be used as pi/M instead of
vooden ones, by boring holes 6 or 8 inches in diameter and say six feet deep,
aUMi ramming the sand in wet. It is necessary to cover the surface with
||^^**X"g or concrete to preyent the earth pressing upward. AUuyial soils
are considered by Baker safe under a load of one-halxto one ton per square
foot.
Wbfltt the earth is unsuitable in nature to support foundations, it is com-
non to drive piles, on the tops of which the foundation is then built.
Wl&en possible the piles are driven to bed rock, otherwise they are made of
•ncl& length and used in such number as to support the superstructure by
roaenn of the friction of their surfaces in the soil. Where the soil is quite
0of t tt is also common to drive piles in large number all over the basement
tti«a In order to consolidate the earth, and make all parts of a better bearing
enuUity.
Piles must be driven and cut off below the water level, and a grillage of
lieary timbers or a layer of broken stone and a capping of concrete must be
plaeea on top of them for supporting the foundation.
The woods most used for piles are spruce and hemlock in soft or medlum-
•of t soils, or when they are to be always under water, hard pine, elm, and
beech in firmer soils, and oak in compact soils. When piles are liable to be
alternately wet and dry, white oak or yellow pine should be employed.
Piles should not be less than 10 inches in diameter at the small end, nor
more than 14 inches at the large end. They should be straight-grained, and
hare the bark remored. The point is frequently shod with an Iron shoe, to
prerent the pUe ft^m splitting, and the head is hooped with an iron band to
iverent splitting or brooming.
Bmi^ M^mmA mm Pll«a.
Banklne gives as safe loads on piles 1,000 pounds per square inch of head,
if drlTcn to firm ground; 200 pounds, if in soft earth, and supported by
MaSi-* Sanders, U. 8. Bngineers, glTcs the following rule for finding the
safe load for a wooden pile driven until each blow drives it short and nearly
equal distances:
- . . , Weight of hammer in pounds x fall in Inches
Safe load in pounds s= 8 X inches driven by last blow
Trautwine's rule is as follows :
, ,. , *VFall in feet x Lbs, wgt. of hammer X JOB
extreme load in gross tons = inches driven by last blow + 1
He recommends as safe load one-half the extreme load where driven ia
firm soils, and one^ixth when driven in soft earths or mud. The last blow
ihould be delivered on solid wood, and not on the ** broomed " head.
Piles under Trinity Church, Boston, support two tons each.
Piles under the bridge over the Missouri Kiver at Bismarck, Dakota, were
drtrea into sand to a depth of 82 feet, and each sustained » Joftd of 20 tons.
▲ pUeunder an elevalor at Buffalo, K. Y., driven into the soU to a depth
sf ISteet, sustained a load of 86 tons.
1292 FOUNDATIONS AND STRUCTURAL MATBKIALSL
AmmS^meiftt of Pile*.
Under walls of a building piles are arranged in rows of two or tiiree, i
24 inohee or ao inches on centers. Under piers or maehlne foniMlatioBS tfaey
are arranged in groups, the distance apart oeing determined by tbe weight !•
be stq»poned, but ususily, as above, irom two to three feet apart on
ii
As mentioned in a previous paragraph, oonerete is now used to a ver
*eat extent for foundation beds, not only in soft earths, bat to lerrei 19 ifl
Inds of foundation beds.
Qood proportions are by measure, using Portland cement :
Cement, 1 part: coarse sand, 2 parts; broken stone, 6 parts.
Only hard and sharp broken stone that will pass through a 1|- or liait
ring snould be used : and the ingredients should be thoroug^hly mixed dqf,
and after mixing, add Just as little water as will fully wet the material.
Concrete should be placed carefully. It is never at its best when droopii
any distance Into place. It should be thoroughly rammed in stx-or nine-iaeb
layers, and after settins the top of eaoh layer should be eleaned, wet, sei
roughened before depositing another layer over it. It is common praetkets
place stde-bosjiyds in trenches and foundation excavations in <»tier tosavecee-
crete. l^kis is economical, but not good praotioe, if the earth ia erea modis
ately firm, as flUing out the inequalitieB makes the foundation mnehiistf
and steady in place. Wol^t of good oonerete per oubio foot is 190 to IMtta
dry.
Wmwamdmtiwmm of Bngrlnoa.
John Toung, Ayr, Scotland, says that brick is more resilient than eoaersla
Foundations should weigh 2^ to 4 times that of its engine, depending m
whether horixontal or vertical type, also on the outside forces, belt p^
direction, etc.
He also advises a concrete bed 2 to 3 feet deep of Portland cement co»
Crete, and for large work, coating the earth under the oonerete with a^hstt
before concrete is laid.
This helps preventing rise of moisture in foundation masonry.
P»raalaalM« I^onAa on J— tlsfctlon
Piles, in Arm soil, each pile, 30,000 to 140.000 lbs.
Plies In made ground, each pile, 4,000
Clay, 4,000
Coarse gravel and sand, 2,500 to 3,600
Bock foundations, average, 20.000
Concrete. 8,000
New York City laws, no pile to be
weighted with a load exceeding, 40,000
New York City rulu for solid nat-
ural earth per superficial foot, 8,000
Concrete Vonndatfomi.
One of the best foundations for engines or other heavy machinery is coa-
structed wholly of concrete, rammea in a mold of planking. The mold ess
be made of any desired shape ; the holding-down bolts placed by temidste,
and the material rammed in layers not exceeding 12 inches thick.
la
(«
Re«lnforc«d Concreto.
Re-inforced concrete, or Concrete and Steel Construction, is being umA
quite extensivelv at the present time for bridges, foundations, recaiusi
walls, floors, ana even entire buildings.
When made of the very best Portland cement and good shan> sand sad
hard broken dt-one all properly Incorporated, and when the Imbeadlng of tka
steel bars Ib carefully ana conscientiously done, the results will prove sati^
factory in that class of work for which it is adapted.
lirick Fonndaa«na*
Only the be^t hard-bnrnod brick should be used for foundations, and they
should be thoroughly wet before lading. To Insure a thorough wetting, the
M0RTAB8. 1293
»riclK0 slionld be deiMtlted in tk tab of water. Brtekg ihonld I»pm9hv9aeed
n. A good rich cement mortar. Grouting abould nerer be QBed.as It takes too
ong to dry. Joints should be very small. A well-constmcted brlok fonnda-
lon will break as easily in the brlok as at the Joints after it has been built
for some time.
Stone Voiuidatioms.
XtTibble stone fonndations should start with large flat stones on the bottom.
S&re must be taken that all are well bedded in mortar, and that the work is
irell Ued together by headers.
I>iineiision stone fonndations are always laid out with the heary and thick
Btouee at the bottom, and gradually decreasing in height, layer by layer, to
kite top. A large cap-stone, or several if the size is too great for one, is often
plsbO«a on top of the foundation. Care must be taken to bed each stone In
Bwinoiit mortar, so that the Joints will be thin and yet leave all the spaces
betD^een the stones completely filled with mortar to prevent any unequal
trains on the stone. In all larse foundations use plenty of headers ; and if
tike tracking or center is of ruoble, see that all stones are well bedded, and
th« orevioes filled with spawls and cement.
One of the best and now most common methods of constructing founda-
tions for piers, walls, columns, etc., is the use of steel I-beams set in con-
crete. Knowing the weight to be supported and the bearing value of the
soil, excavation is made of the right dimensions to get the proper area of
bearing, then I-bearos of (A-edetermiued dimensions are laid parallel along
tbe bottom, and hald in place with bolts from one beam to the next. Concrete
ia rammed in all the spaces to a level with the tops of the beams. Another
aimilar layer of beams is then laid on top of the first, and at right angles
thereto, and the spaces also filled with concrete. The column base, or foot-
ing course, is then set on the structure ready to receive the column.
For method of calculation of dimensions of I-beams for use in foundations
for piers and walls, the reader can consult the hand-book of the Carnegie
Steel Company, and those of other Steel Companies.
MOATAJKS.
Ume Mortar.
Good proportions are : 1 measure or part quicklime, S measures of sand,
well mixed, or tempered with clean water.
Q,aaatl(y rooalred.— Trautwine. 20 cu. ft. sand and 4 cu. ft. of lime,
making about 22f cu. ft. mortar, will lay 1,000 bricks with average coarse
Joints.
'WefcM. — 1 bbl. weighs 230 lbs. net, or 2S0 lbs. gross ; t heaped bushel of
lamp Ume welshs about 76 lbs. ; 1 struck bushel ground quicklime, loose,
weighs about 70 lbs. Average hardened mortar weighs about 106 to 115 lbs.
per cu. ft.
Veaadtr. — Ordinary good lime mortar 6 months old has cohesive
strength of from 16 to 30 lbs. per sq. Inch.
Adbesloa to contnsoa bricks or rabble.— At 6 months old, 12 to
91 lbs. per sq. inch.
Geasoat Mortar.
Good proportions are : 1 measure cement, 2 measures sand, i measure
water. The above is rich and strong, and for ordinary work will allow in-
crease of sand to 3 or 4 miasures.
4itaaatftjr reqnlred.— Trautwine. 1 bbl. cement, 2 bbls. sand, will
lay 1 cu. yd. of bricks with | inch Joints or 1 cu. yard rubble niasoniy,
iiroifbt.—
American Rosendale, ground, loose, average, 66 lbs. per cu. ft.
" " U. S. struck bushel,
ISnglish Portland,
** * per struck bushel,
•* «• per bbl.
70
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81 to 102
It
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100 to 128
*<
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400 to 430
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1294 FOUKDATIOXS AND STBtTCTUSAIi MATBBIALS.
Mvwwtti •f BTmi* C«M«Bt
PortluMl, MtifloUl . . .
** Baylor's nalnnU
U. 8. oommon hjdraulio .
Tensile, Lbt.
per sq. in.
90O to80O
170 to 370
40to 70
Compress, Lbs.
per sq. in.
1400 to 8100
1100 to 1700
SBOto 400
COBDpnHt
Toaispersq.lt
MtolM
Tltolli
l««oS
dementi are weakened by the addition of sand somewhat
following table : eaUing neat oement 1.
aa shown la Hi
Band.
0
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4
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S
3
4
1
6
6
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Adhesion of eement. either neat or mixed with sand, will avenife akeel
three>foiirths the tensile strength of the mortar at the same age.
•JUnD Aim CKHUBVT.
Beoommendatioas of Am. 8oe. OiTil Engineers.
1. — To be crashed qaartz only. To pass,
let sieve, 400 meshes per square inoh.
2d ** 900 ** " •* "
Sand to pass the 400 mesh, but be caught by the 000 meah, all tear psrt^|
eles to be rejected.
IPorttead C«HseMt« — For fineness, to pass,
1st siere, 9600 meshes per square inch.
2d " 5470 " " " *•
8d " 10000 " " " "
Should be stored in bulk for at least 21 days to air-slake and free it fnns '
lime, as lime swells the bulk, and if not removed is apt to eraek the wofk.
Oir AJm ATKSI*.
Csst, .2004 Lbs.
Wrought, .2777 "
a = sectional area wrou|^t4ron bar.
X = weight per foot **
est. ft.
4B0IAW.
480 "
It «i
a =
8«
10
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lgkt«ft
x =
.2881 Lbs.
lOa
ft.
480.3 Lbs.
Caat I
Bar an inch square, supported on edgss 1 foot i^art, must sustain 1 tea at
eenter.
WBIQHT OF FLAT BOIiLED IBOST.
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1296 rOUNDATIOMS AND STBUCTURAI. MATKRIAIA
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02^
301
IJOS
3S.58
28.73
120.0
S4JB
sn
1.237
3T.W
12S.I
t&^
xa
30.38
102.3
S.W1
i™
40.83
si.V!
13s!6
109.4
J»2
2.0M
42.30
33.23
1*0.8
110,6
2.830
.333
:
3.7W
ZSK
48.88
36.81
48.4S
38.ae
1J8.3
.308
:s{
^
a33
4o!ss
41.88
1813
Ik5 "
'.MB
4.fl60
187 Ji
147.» *
0.888
44!»
162.3
.no
siwo
KM
6,395
60.21
47!20
2087
162J
i)m
61 .98
48.00
213.3
167^ ■
.402
t!iu
83.80
(UI
8.018
65.8*
210:8
m£
07^0
63.01
2W.2
V»A
68.30
sisss
2SS!2
sn'jt
3
^
10.«T
73.94
236.3
75.21
60,07
348.0 7
77.20
00.03
333.3
X
ill
62.2S
03.82
28b!6 '
xt
83:33
6S.4S
38B,2
302 JS
A
87.10
M
y
16.30
I
70!4B
44018
346.2
IT. IB
y
01.88
72.18
400.2
S6M
MJT
A
StJ»
73.88
13
480.
377.
n
[i
I
aATJQB FOR SHKKT AND PLATE IBON. 1299
v. •. •sAVDAan fiAiTSB ram bhkbv aitb
H.AVH UOH AMD •TBB1» 1»*S.
1300 FOUNDATIONS AND STRUCTURAL MATERIALS.
JL
P= Qrushinff welgbt in poandB ; d = exterior diuneter in incbes; d,:
interior diameter in Inches ; L = length In feet.
Kind of Golnmns.
Solid cylindrical col- )
umns of cast iron . )
Hollow cylindrical )
columns of caet }
iron )
Solid cylindrical col-)
umns of wrought}
Iron )
Solid square pillar of )
Dantxic oak (dry) .f
Both enda rounded, the
length of the oolumn
exceeding 15 times its
diameter.
P=z
P =
33,380
20,130
Both ends flat the
length of the eohiHs;
exceeding 30tiai«s iM <
diameter.
L^'i
P = 96,800
P=: 96,920
P =99320
/^•»
P = 299,000
L*
P = M,540^,
These formulas applyonly to cases of breakage caused by bending rstbr
than mere crushing, where the column is short, or say five times Us dlaa-
eter in length, then the following formula applies.
Let
P = ralne glren in preceding formiilie,
K = transverse section of column in square inches,
Czz ultimate compressive resistance of the material^
W^ crushing strength of the oolumn.
Then
W =
PCK
P-\-iCK'
Hodgkinson's experiments were made upon columns the longest of vUek
for oast iron was 00^ inches, and for wrought iron 90| inches.
The following are some of his conclusions :
1. In all long pillars of the same dimensions, when the force is mpUtd ii
the direction of the axis, the strength of one which has flat ends is abosk:
three times as great as one with rounded ends.
2. The strength of a pillar with one end rounded and the other flat ii as
arithmetical mean between the two given in the preceding ease of the su
dimensions.
8. The strength of a pillar having both ends firmly fixed is the sanwai
one of half the length with both ends rounded.
4. The strength of a pillar is not Increased more than one-eeventh bye
larging It at the middle.
^oi^on's formalse, deduced from Hodgkinson's experiments, an
more generally used than Hodgkinson's own. They are :
Columns with both ends fixed or flat P =
- fS
Columns with one end flat, the other end round, P =
fS
1 + lAi^
Columns with both ends round or hinged, P =r
fS
r+4a
!»•
8TBBNGTH OF MATERIALS. 1301
8 = area of oroes section In Inohet x
J* = ultimate resistance of column in pounds ;
y := omahing strangth of the material In pounds per square Inch ;
_ , . ., - *i . * 1, ^ Moment of inertia
r = least radius of gyration, in incliee, r* = 3 n ;
"^ * * area of section '
I =r length of column in inches ;
a = a oMfficient depending upon tiie material ;
f and a are usually taken as constants ; they are really empirical raria-
»e«, dependent upon the dii
npon the material. (Burr.)
blea, dependent upon the dimensions and character of the column as well as
ipon the material. (Burr.)
For solid wrought-iron columns, ralues commonly taken are : /= 36,000
feo 40.000 : a = — -— to — — - .
• ' 96,000 iO/WO
New York City Building Laws 1897-1896 give the following ralues for/ :
Cast iron /=aO,0001bs.
Boiled steel .... /= 48,000 lbs.
Wrought or rolled iron /=40/)OOll>s.
American oak . . . /= 6,000 lbs.
Pitch or Oeorgia pine. /= 6,000 lbs.
White pine and spruce /= 8,600 lbs.
For solid east-iron columns,/ = 80,000, a = gjnQ-
80 000
For hollow cast-iron columns, fixed ends,^? = 7,, / = length and
1 + 800:^5
d = diameter in the same unit, andp = strength in lbs. per square inch.
Sir Benjamin Baker gires.
For mild steel / = 67,000 lbs., a = -^jj^*
For strongsteel / = 114,000 lbs., a = ^^.
The terms ttre$$ and itraikn are geiierallT used sjrnonymously, authorities
differing as to which is the proper use. Merriman deilnes »trti9 as a force
whioh acts in the interior of a body, and resists the external forces which
tend to change its shape. A d^iMrfnation is the amount of change of shape
<tf a body caused by the stretM. The word ttrain is often used as synony-
mona with «<reM, and sometimes it is also used to designate the deforma-
tion. Merriman gives the followins general laws for simple tension or
compression, as having been eBtablisneu by experiment.
a. When a small stress is applied to a l)ody, a small deformation is pro-
duced, and on the removal of the stress the body springs back to its original
form. For small stresses, then, materials may be regarded as perfectly
elastic.
b. Under small stresses the deformations are ^proximately proportional
to the forces or stresses which produce them, and also approximately pro-
portional to the length of the bar or body.
c. When the stress is great enough, a deformation is produced which is
partly permanent; that Is, the body does not spring back entirely to its
original form on removal of the strcHs. This permanent part is termed a
set. In such oases the deformations are not proportional to the stress.
d. When the stress is greater still, the deformation rapidly increases, and
the body Anally ruptures.
s. A sadden shock or stress is more injurious than a steady stress, or than
a stress gradually applied.
1302 FOUNDATIONS AND STRUCTURAL MATBRIAL8.
1
Th« ekMlieHmK of a material onder twfe for teaalle strength is
the point where the rate of stretch begins to inerease. or wliere tha w.
madons cease to be proportional to the stresses, and tiie body loses
power to ret am oompletely to its former dimensions when the stress is f-
mored.
M«d«l«a 9r KlttBttcltj.
The modulus or eoeJIeimU of eUuHcitM Is the term ezprearing the telartw
of the amount of extension or compression of a material under stress to As
load jproduoing that stress or deformation. It is the load per nnit at
dirlded by the extension per unit of length.
If P = applied load,
k = sectional area of piece,
I = length of the part ettended,
k = amount of extension,
if = modulus of elsstioitT,
k' J" k\
Following are the Moduli of elastiolty for Tarlons materials.
Brass, oast 9,:70,4IOO
** wire 14,830,000
Copper 16,000,000 to 18,000,000.
Lead IfiOOJMO ij
Tin, oast 4,000,000
Iron, cast 18,000,000 to 87,000/MM) (?)
Iron, wrought 33,000,000 to 30,000^000
Steel 36,000,000 to SifiOOfiM
Marble 26,000,000
SUtte 14,600,000
Glass 8,000,000
Ash 1,600,000
Beech IJOOilOO
Birch 1,860,000 to IJSBO/IM
Fir 800,000 to 8,191,000
Oak 974/X)0 to 8,283AXM>
Teak 2,414,000
Walnut 906/NIO
Fine, long-leaf (butt-logs) . . 1,119,800 to 8,117,000 Avemge, l,|aMI
This may be defined as the factor by which the breaking strength «#•
material is dirlded to obtain a safe working-streis. The factor of safety k
sometimes a rather indefinite quantity, owing to lack of InfonnatfcMi silt
the strength of materials, and ft is now becoming common to name adifr
nite stress which is substantially the result of dlTiolng the average streaftti
by a factor.
The following factors are found in the '* Laws Relating to Boihllnf ta
New York City," 1897-1896.
For beams, girders, and pieces subject to transrerse straina, Caetor*
safety = 4.
For wrought-iron or rolled-steel posts, oolnmns, or other Tertieal wtt
pcwts, 4.
For other materials subject to a oompressiTe strain, 6.
For He-rods, tie-beams, and other pieoes subject to tensile strain, t.
The moment of inertia of a body about any axis, Is the smn of tiie piudseH
of the mass of each particle of the body. Into the square of its (least) 4lt
tance from the axis.
^
momskt of i2txbtia. 1303
hamta ov «yravkov.
th» radius of gyration of a ieetion 1a the square root of the qiiotleni of
• moM^nl q^imertiat dirlded by the area of the eeotlon, or
Badlm of gyration r= J Moment of In^
*' V Area of section.
The radina of gyration of a solid about an axis Is equal to the
i
Moment of Inertia
Mass of the Solid
'MJmm im thm Wnmmim for •tiwMTtli mt CMvd«n
The strength of sections to resist strains, either as girders or as
olomns, depends on the form of the section and Its area, ana the property
f the section which forms the basis of the constants used In the zonnuls)
or strength of girders and columns to express the effect of the form, Is its
noment of Inertia about Its neutral axis. Thus the moment of resistance
\t any section to transverse bending Is its moment of inertia dlylded by the
Ustance from the neutral axis to the fibers farthest removed from the axis ;
ir
«-. ^ . . . Moment of inertia ,_ /
Moment of resistance = tvtt s — : si: — szr r-. if s= — .
Distance of extreme fiber from axis s
MMMest ef Msevila •€ C«aip«wi« Slutpes.
(Penooyd Iron Works.)
The su>ment of Inertia of any section about any axis Is equal to the / about
t parallel axis passing through Its center of gravity 4- (the area of the sec-
tion X the square of the distance between the axes).
By this rule, the moments of inertia or radii of gyration of any single sec-
tions being known, corresponding values may be obtained for any combina-
tion of these sections.
Ins •f Cljratl«n mt O^nipnnndi Slu^pes.
In the case of a pair of any shape without a web the value of H can always
be found without eonsiderlnig the moment of Inertia.
The radius of gyration for any section round an axis parallel to another
ixts passing through Its center of gravity Is found as follows :
Let r = radius ca gyration around axis through center of gravity ; J2 =
ndlus of gyration around another axis parallel to above ; d = dlstuice be-
tween axes :
When r is small, K may be taken as equal to d without material error.
MMJBMMJI'A'» 09 UfflTAX •■CTIOM*.
Moments refer to horlsontal axis through center of gravity. This table Is
Intended for convenient application where extreme accuracy Is not impor-
tant. Some of the terms are only approximate ; thoee marked * are cor-
reot. Viines for radius of gyration in flanged beams apply to standard
minimum sections only.
A = area of section ;
b =z breadth ;
h r= depth :
i)= diameter.
(
• •
1304 F0UKDATI0N6 AND 8TBU0TUBAL MATERIALS.
^
•
Shape of Section.
Moment of
Inertia.
* *
Moment
of
Resistance.
Sqaare of
Xeast
Radius of
Gyration.
RadiiB«(
GyiatiBL
__^__
bh-
6
j_ Solid Bect-
(^»)» iL««.-dH
^ angle.
\ Btae /
1 3.46
12
*-^-
i Hollow Eect-
^. aiBgU.
x.
6A«— 6iV*
6A*— 6A»«
A« + V»
A+*.
18
«b
13
4S
^ -b--'
€
^ Solid Circl«.
16
8
IP*
16
4
H Hollow Circle
. A^ area of
1 . large section ;
/ a, area of
^ small section.
XD«-HWP
Al^-ad*
16
1>+*
16
az>
6JI
A
.* Solid
l_ 1. Triangle-
36
6M
24
Hie least
of the two:
h* h*
— or —
18 94
Tbelisil
of thetvo:
l*-^->
4^*U
"4r
•^ Bven Angle.
Ah*
10.2
^A
7^
6*
26
A
6
h'b—
¥■
T ""
9.5
Ah
6.5
(A*)»
A»
13(A»+6«)
2.6 (A + t)
(.*-.
^
H^ Even Cross.
jl
19
JA
9.6
A*
22iS
A
4.74
J
i Even Tee.
Ah*
11.1
^A
8
6>
22 JS
ft
r-J^
2L
4.74
i.;!-
^
^>k
-y I-Beam.
6.66
Ah
3.2
6»
81
A
4J»
1
Ah*
7.34
XA
3.67
13J»
^d
T, Channel.
ft
■^>;
N-< Deck Beam.
-•
619
Ah
4
5»
36.5
ft
C
Distance of base from center of gravity, solid triangle, -= ; even sn^
A A A A **
-jj; uneven angle, -^; even tee, -^i deck beam, ^ ; all other thaftf
given in the table, ^ or — •
EliEMEKTS OF UBUAL SECTIONS.
1305
Table, baaed on Hodgkiii8on*8 formula (gross tons).
The figures are one-tenth of the breaking weight in ton«, for solid col-
Qmna, ends flat and fixed.
a .
Length of Golamn in Feet.
i|
1
P^A
6.
8.
10.
12.
14.
16.
18.
20.
26.
w
.82
JBO
.34
.26
.19
.16
.13
.11
.07
1.43
JR
.00
.44
.34
.27
.22
.18
.13
2
2.31
1.41
.97
.71
£6
.44
.36
.30
.20
21
SJS2
2.16
1.48
1.06
.83
.67
XA
.46
.31
2t
6.15
3.16
2.16
\Jb^
1.22
sn
.80
.66
JS6
^L
7.26
4.45
3.06
2.23
1.72
1.37
1.12
.94
.64
3
9M
6.00
4.17
8.06
2.36
1.87
1JS3
1.28
.88
H
17.W
10.60
. 7.98
5.32-
'4.18
3.26
SjOT
2.28
•1J»:
7
27 JM
17.16
11*78
8b81
64»
5.28
4.82
&ai
2.47
4
42.73
26.20
17.83
13.15
10.12
8.07
6.60
6.52
3.78
r
62.44
88.29
26.20
19.22
14.79
11.79
9.66
8.06
6JS2
6i
88.00
63.97
36.93
27.09
20.84
16.61
13.60
11.37
7.78
6^
120.4
73.82
BbAl
37.06
28.51
22.72
18.60
15.55
10.64
64
160.6
98.47
07.38
49.43
38.03
30.31
24.81
20.74
14.19
r
200.7
128.6
87.98
64 J»
49.66
39.57
32.30
27.08
18^
7k
268.8
164.8
112.8
82.73
63.66
60.73
41.53
84.72
23.76
8
338.1
207.9
142.3
104.4
80.31
64.00
52.39
43.80
29.97
8^
421.8
268.6
177.0
129.8
99.90
79.61
65.16
54.48
37.28
r
618.2
317.7
217.4
169.6
122.7
97.80
80X»
66.92
45.80
H
629.6
386.0
264.2
193.8
149.1
118.8
97.26
81.70
65.64
10
767.2
464.3
317.7
233.1
179.8
142.9
117.0
97.79
66.92
10|
902.6
663.6
378.7
277.8
213.8
170.3
139.4
116.6
79.77
11
1067.1
664.4
447.8
328 JS
262.7
201.4
164.9
1.17.8
94.31
111
1252.3
767.9
625JS
385.4
296.6
236.4
193.5
161.7
110.7
12
1460.6
806.1
612.5
449.3
345.7
275J>
225 Jl
188.6
128.0
Where the length is less than 30 diameters,
Strength is 'tons of short colamns := ^^J .'w^y*
105 -|- \Cy
8 being the strength siren in the above table, and C= 49 times the seo-
ttonal area of the metal in inches.
follow ColvnsBa.
Tbe strenffth nearly equals the difference between that of two solid col-
omns, the diameters of which are equal to the external and internal diam-
eters of the hollow one.
More recent experiments carried out bj the Building Department of New
York City on full-size cast-Iron columns, and other tests made at the
Watertown Arsenal on cast-iron mill columns, show Gordon's formula,
based on Hodgkinson*s experiments, to give altogether too high results.
Tbe following table, from results of the New York Building Department
tests, as published in the Engineering Xew*^ January 13-20, 1898, show actual
results on columns such as are constantly used in bulldingH. AppWlng
Gordon's formula to the same colamns gives the following as the breaking
load per square inch. For 15-lnch columns, 57,000 lbs.; for 8-inch and 6-Inch
eolumns, 40,000 lbs., all of which are much too high, as shown by the table.
Prof. Lansa gives the average of 11 columns in the Watertown tests as
tt,600 pounds per square inch, and recommends that 5,000 pounds per square
inoh be used as the maximum safe load for crushing strength.
r
1306 rOUNDATIONS AND STBUGTURAL MATERIALS.
f
VM«e •r CMt-lr
•a G«lwi
UM.
Thiekneflt.
Breftktaif Loud.
Number.
Inches.
/■
Max.
Mfn.
ATenge.
pereq. il
1
15
1,866^000
8MV
2
16
1^
4
1*880,000
27,181
8
16
l(^
If
1488,000
9IJNI
4
!S^
IJL
If
1,918,000
Vm
6
16
lX|
lb
1^832^000
ss
6
16
l|
1
jA
2,082,0004-
4B,4»f
7
7|to8J
ij
861,00
n^
8
8
^A
lA
812,800
9
10
tk
\f
i}.
IS
400,000
466i300
98^
(PottsTllle Iron and Steal Co.)
Computed by Gordon*! formula, p =: ^ ^
i+c(^)
p = Ulthnate ttrengtb In lbs. per square ineh ;
^^ ( 40,000 lbs. for wxx>aght iron; I
I OOjOOO lbs. for east iron; j
C =: i/aooo for WTOoght Iron, and 1/1
For oast iron, j» =-
1/800 for oast iron.
80,000
1 +
For wrought iron, p =
mo(a)
800
40,000
1 +
^V*)
8^000'
HaUaw OrUaArtcal G«li
Ratio of
Maximum Load per sq. in.
Safe Load per Square laek.
Length to
Diameter.
X
Cast Iron.
Wrought Iron.
Cast Iron,
I^torof 6.
Wrou^t IroB.
Faeloi-ofi
8
74076
89164
128«6
9791
10
71110
88710
11861
9877
12
67796
88168
11299
9Btt
14
64266
87648
10709
9886
18
60006
88864
10101
9813
18
66038
88100
9189
9828
20
68332
86294
8889
8823
22
40646
844^
8307
8818
24
46610
88666
7761
26
48860
82842
TSV
8ICI
28
40«04
81712
6784
T90B
80
37646
80768
6B74
7889
^
BLBMBirrs or usuai< sections.
1307
H*ll«w CjrHmdirlcal C«lw
■iaa.— OMliiMied.
Ratio of
Maztmum Load per 8q. In.
Safe Load per Square Ineh.
Jjength. to
IMameter.
1
h
Cast Iron.
Wrought Iron.
Oaatlron,
Faetor of 6.
Wrought Iron,
Faetor of 4.
82
36068
29820
6848
7466
M
8S718
28874
6463
7218
38
30684
27982
5097
6983
38
28520
27002
4758
6750
40
MAM
20086
4444
6532
42
2tt82
26188
4160
6297
44
23396
24310
ooBv
6077
48
21948
28464
8668
6883
48
20618
22020
8436
6656
60
19302
21818
3282
6464
68
18282
21088
8047
6258
64
17222
20284
2870
6071
68
16200
19566
2710
4889
68
16868
18858
2661
' 4714
80
14644
18180
2424
4646
p = ultimate strength per square inch;
I =: length of oolumn In Inches:
r =: least radius of gyration in inches.
For square end-bearings, p =:
For one pin and one square bearing, p =
For tvopln bearings.
P =
1 +
20000
w
Por safe working-load on these columns use a factor of 4 when used in
buildings, or when subjected to dead load only; but when used in bridges
the factor should be 6.
C«Ii
Ultimate Strength in Lbs.
•
Safe Strength in Lbs. per
1
per Square Ineh.
1
f
Square Inch — Factor of 6.
r
Square
Ends.
Pin and
Pin
Square
£bids.
Pin and
Pin
Sq. End.
Ends.
Sq.End.
Ends.
10
89944
OWSDD
38900
10
7989
'965
7973
7960
16
39778
30702
39664
16
7940
7911
90
39604
39472
39214
20
^921
7894
7848
26
39884
39182
38788
25
7877
7888
77b8
80
38118
38834
38278
30
7821
7767
7666
86
38810
38430
87690
36
7762
7686
7588
40
88480
37D74
37086
40
'692
7596
7407
46
380T2
37470
36822
46
'614
7494
7984
60
87848
36928
36626
60
'829
7386
7106
66
37188
36336
34744
65
V437
7267
6949
80
86097
86714
33898
60
V338
7148
8780
86
86182
84478
33024
66
V236
6896
6606
70
85884
9W10V
32128
70
^127
6877
6426
76
850T8
83682
81218
76
015
6736
8944
80
84482
^IQ^yi
30288
80
6896
6593
6058
86
38888
32386
29384
85
6777
8447
5877
90
83884
81486
28470
90
6653
8299
6694
86
89838
30760
27662
96
6627
6160
6612
100
82800
SOuOO
100
6400
6000
5888
105
81367
29260
25786
106
6271
6860
6167
1308 FOUKDATIONS AKD STRUCTURAL BCATERIAIiS.
TnuMTerM strength of bus of rectangular section is fomid to varj «B-
rectly as the breadth of the specimen tested, as the square of its depth, sad
inversely as its lensth. The deflection under load varies aa the cube oC tks
length, and Inversely as the breadth and as the cube of the depth. Alfs-
bralcally, if iS' = the strength and 2> the deflection, I the length, b tks
breadth, and d the depth,
S varies as -y- and D Taries as r^.
To reduce the strength of pieces of various sises to a common staadaid,
the term modtUut of ruptwrt {R) is used. Its value is obtained by ezpsri-
ment on a bar of rectangular section supported at the ends and loaded ii
the middle, and substituting numerical values in the f oUowixtg f ormnla :
in which P = the breaking load in pounds, I = the length in inches, h tbt
breadth, and d the depth.
1
(Merrlman.)
Resisting shear = vertical shear ;
Resisting moment = bending moment ;
Bum of tensile stresses = sum of compresslTe stresses ;
Resisting shear = algebraic sum of ail the vertical components of Uw ia-
temal stresses at anv section of the beam.
If A be the area ox the section and S* the shearing unit stress, then resist-
inff shear = AS* ; and if the vertical shear = T, then r= ASm.
The vertical shear Is the algebraic sum of all the external vertical fore«
on one side of the section considered. It is equal to the reaction of onessp-
Sort, considered as a force acting upward, minus the sum of all the vcrtied
ownward forces acting between the support and the section.
The resMing momerd = algebraic sum of all the moments of the intW'
nal horizontal stresses at any section with reference to a point in that ee^
SI
tion, = — , in which S= the horizontal unit stress, tensile or compiSMire
as the case may be, upon the fiber most remote from the neutral axis, e =r
the shortest distance from that fiber to said axis, and /^ the momeotof
inertia of the cross-section with reference to that axis.
Hie bending moment M is the algebraic sum of the momefit of theextenal
forces on one side of the section with reference to a ooint in that secti<ni =
moment of the reaction of one support minus sum of moments of loadi be-
tween the support and the section considered. •
e
The bending moment is a«compound quantity r= product of a force by tbe
distance of its noint of application from the section considered, the disuaee
being measurea on a line drawn from the section perpendicular to thedire^
tion of the action of the force.
Concerning the above formula, Prof. Merrlman, Bng. J^eirs, Jnly 21, IM
says : llie formula just quoted is true when the unit-stress S on the part el
the beam farthest from the neutral axis is within the elastic limit of die
material . It is not true when this limit is exceeded, because then the neiittsl
axis does not pass through the center of gravity of the croes section, sod
because also the different longitudinal stresses are not proportional to thctr
distances from that axis, these two requirements being involved in the d^
duction of the formula. But in all cases of design the permissible oiiit-
strebses should not exceed the elastic limit, and hence the formula i^>plu«
rationally, without regarding the ultimate strength of the material or sbt
of the circumstances regarding rupture. Indeeo, so great reliance is placed
upon this formula that the practice of testing beams by rupture has beoi
almost entirely abandoned, and the allowable unit-strtssses are mainly de-
rived from tensile and compressive tests.
TRANSVERSE STRENGTH.
^
1309
i
I
1
I
s
F» !M
«Him<-i 100*
'e-^'^e
5l''S3hS3h5l''Sh^h5l«S3h5l» 51"
II
ft,
S
A,
II 11 II 11 II
^ b^ (C »« •»• tv
fe ^*«.fl; s; fe 7
-* 100
ft,
11 1^
CO 100
I
9
t
S
I
I
I
I
e
IN
I
ft,
I
1^
-^l?2-.
1-1 i«o r-i too « l« ^ l« ^ leo <* I w •
Oil ft;| o;| S;| c; ,o '^§
il
fe: «i
II
i
II II
ft:
m
O
,d
OS
1
•a
o is
3 1
O .4
S
•s
o
9
::9
.a
M
a>
•9
I
I
a
5 •
2 a
s I
^ o
"g
- 2
I 1 I
-- I
1 1
I I "2
OQ OQ m
2
s
I ^
.a -
I I
PQ I
«
a
o
.d
e8
« a
•d
2 "S
s
o
g
£
00
1310 FOUNDATIONS AND STRUCTURAL KATEBIAXS,
«•« Mreagth •/
V^rBialn for
(Referring to table on preeedlng pege.)
P = load at middle ;
H^= total load, distribated uniformly ;
I = length ; b = breadth ; d = depth, in inches ;
JP = moaulus of elasticity ;
B = modalus of rapture, or stress per square inch of extreme
/= moment of inertia ;
0 = distance between neutral axis and extreme liber.
For breaking-load of circular section, replace M* by OJMki*.
For good wrought Iron the value of J2 is about 80,000, for ateel steeft
laoUXX) the percentage of carbon apparently having no influence. (Tbsn-
ton?" iron and Steel," p. 4010 , ^ ^
For cast iron the value of R varies greatly according to quahty. Thunns
found 46,740 and 07,900 in No. 2 and No. 4 east iron, respectively.
For beams fixed at both ends and loaded In the middle. Barlow, by ex|Mn-
ment. found the maximum moment of stress = iPl instead of \J% there-
sult given by theory . Prof. Wood C * Beidstance Materials/* p. 1B5) sap ofw
ease;" The phenomena are of too complex a character to admit of a tbonegi
and exact analysis, and it is probably safer to accept the resvlts of Mr. Bv-
low in practice than to depend upon theoretical resnlta."
OM
(Penooyd Iron Works.)
Based on fiber strains of 10,800 lbs. for steel. (For iron the loads shooM te
one-sixth less, corresponding to a fiber strain of 14,000 lbs. per square lacN
L = length in feet between supports ;
A = sectional area of beam in square inches ;
2> = depth of beam in inches ;
a — interior area in square inches ;
d = interior depth in Inches ;
IS = working-loiMl in net tons.
Shape
Section.
Greatest Safe Load in Lbs.
Deflection In Inches.
«
Load in
Middle.
Load
Distributed.
Load in
Middle.
Load
Distributed.
SoUd
Rectangle.
MOXD
L
1880XD
L
8MZ>*
wL*
Hollow
940(AD—ad)
L
1880(^i>— flkl)
L
wlA
»!.>
Rectangle.
SiiAJJ^-^cuP)
62(-rfil«-«^
Solid
Cylinder.
lOHAD
L
VU»AD
L
^AAI^
Hollow
7i»(AD — ad)
L
1400(JZ>-aJ)
L
trl»
wX»
Cylinder.
^AI^-<ad^
2»(AI}^-«m
APPBOXIMATB GRBATB8T 8AFB LOAD IK LBS. 1311
Seotion.
OrMt«st Safe Load in Lbs.
DeAeoUon la laohea.
Load In
Middle.
Load
Distiibated.
Load
in Middle.
Load
Diatribvtod.
Ansleor
930AD
L
IBOHAD
L
IXtAD^
Channel or
ZBar.
imOAD
L
32mAD
L
^AlP
B5AI3^
Deck
Beam.
14Sn^/>
W»AD
L
BOAIP
mAIP
I-Beam.
nSOAD
L
VMAD
L
BSAIJ^
9iAJD^
I
U
III
IV
«
V
The rulee for reotangolar and circular seotiouB are correct, while thoee for
the flanged sections are approximate, and limited in their applicatlMi to the
standard shapes as giyen in the Peneoyd tables.
The calculated sue loads will be approximately one-half of loads that
would inlure the elasticity of the matmals.
The nues for deflection apply to any load below the elastic limit, or less
than double the greatest safe load by tne rules.
If the beams are long, wltiiout lateral support, reduce the loads for the
ratioa of width to span as follows :
Length of Beam.
Proportion of Calculated Load
forming Greatest Safe Load.
90 times flange width.
80 «• " "
40 " •• "
00 " " ••
ao " " «•
70 » " "
Whole calculated load.
9-10 " "
8-10 " "
7-10 " "
6-10 " "
6-10 " ••
These rules apply to beams supported at each end. For beams supported
otlierwlse» alter the coeflleients of the table as described below, referring to
the reapeettTe columns indicated by number.
•r C««fltolenta for Spvcisa Vo
•r
Kind of Beam.
Fixed at one end, loaded
at the other.
Coefficient for Safe
Load.
One-fourth of the coeffi-
cient of col. II.
Coefficient for Deflec-
tion.
One-sixteenth of the co-
efficient of col. ly.
1812 FOUNDATIONS AND STRUCTURAL MATERIALS.
CbaMy— •f C
Ictonts — OonHnued.
Kind of B6*m.
Coeflicient for Safe
Load.
Coefficient of DcAee-
tion.
Fixed at one end, load
evenly distributed.
One-fourth of the ooeA-
cientof col. III.
FiTe forty-eighths of «^
ooeAcietit of eoL V. 1
Both ends rigidly fixed,
or a continuoiui beam,
with a load In middle.
Twice the ooeflldent of
col. U.
Four times the eoeS-
cient of wA. lY. i
Both ends rigidly fixed,
or a c<mtlnuoa8 beam,
with load erenly dis-
tributed.
One and a half times
the coeflicient of col.
IIL
FiTe time* the eocfi- ^
dent of col. T.
Let
tlaa of Bltteticity mmA Klaetic
P = tensile stress in pounds per square inch at the elastie Uait ;
e = elongation per unit of length at the elastic unit ;
E = modulus of elasticity =P-^e;e = P-^E. ]»•
Then elasticity resilience per cubic Inch = |Pe = - -= .
z Jt
BKAHS OF VmUFOltM STmB]ff«TH THSO«7C«01
The section is supposed in all cases to be rectangular throughout,
beams shown in plan are of uniform depth throughout. Thoee shown
elevation are of uniform breadth throughout.
^ = breadth of beam. /> = depth of beam.
Fixed at one end, loaded at tkte
ourye parabola, vertex at loaded end;
TOoportloual to distance ftom loaded
The beam may be reTersed so that the
per ed£6 is parabolic, or both edges mar
parabolic.
Fixed at one end, loaded at the other ;
angle, apex at loaded end ; BU^ pro]
to we distance from the lotaded end.
Fixed at one end; load dlstribnted;
angle, apex at unsupported end; JSJD*
portional to square of distance from
ported end.
Fixed at one end ; load distiibvted : chit
two parabolas, vertices touching eaca odu
at unsupported end ; £13^ proportional to di
tanoe from unsupported oad.
Supported at both ends; load at any
point; two parabolas, vertices atthe_Mteti
of support, oases at point loaded ; B^ jpro-
portional to distance from nearest point of
support. The upper edge or both ediges WJ
also be parabolic.
Supported at both ends ; load at any ot«
point ; two triangles, apiees at points of nr
S>rt. bases at point loaded; BJ3^ propor-
onal to distance from the nearest point of
flupiiort.
Supported at both ends ; load distributed :
eurves two parabolas, vertices at the middle
of the beam ; bases center line of beam ; BJP
proportional to product of distances ttf»
points of support.
Supported at both ends ; load distributed;
curve semi-ellipse ; JSD* proportional to ths
product of the distances fitnn the points of
support.
TBKRTON BBAKS AMD CBAMmU.
131f
ll
8
r
NO
I
S4
OQ
I'
8
s
I
u
I
k
8 S^
I ill
"2-
s «
-lis
§
;;>
S $dSi8SggSS§§§§g§§gSS§§§§{
&
8 5^
p4
Ssl
OD
ie«9«D<ot«oc>ooa»A$3'^3*dr^ia^«iQiO)0€>iOQ
I
§s ■
6 I. o
H'
a* • •-••_?*J^* • * • • J • • • ^« • • • ^» • •
Aw*
8 ®
9 8S$S8!8i8iei6gSSS»S^SJS§SSg88
r^r^ r^ ^^ ^^ r4 r^ w^ a ifm Ci
ii
8.S.;
• •
4 ^io»3«^ioio««<o^io«e ,^ioio«io .lo to
. ^ieiOiO«acOt««ao AOOO OOCIOIO* lO ^
V0^^^
ooS^sssaassass
I
s :::::::: s I : s 55 :|
ssa%assa33S3%ss'.
SIS s :gs§Si »s-
ass
I !§
ssiiaisiass!
ii i i ill
III
ass
III
I s i s s s s
i liii
till
a s 1 I
nil
5 3
sal
i s s
3 9 S
3 3 S ? S S
I
ilillilliifliili
^
WOOD.
1317
In all 0M6t m lane number of teats were made of eaoh wood. Minimum
id maadmmn resmts only are ^ren. All of the teet specimenf bad a see-
tlonal area of 1^5 x iSn inonea. The tranaTerse test specimens were
S0.S7 Inches between supports, and the compressiTe test specimens were
3 l^t
ISJO inches long. Modolns of rapture calculated from formula ^ = s nj-*
J*= load in pounds at the middle, 2 = length in inches* 6 = breadth,
«l = depth:
Name of Wood.
Cucumber tree
Tellow poplar, white wood
White wood, Basswood
Bugar maple, Bock maple
Bed maple
Locust
Wild cherry
Sweet gum
Dogwood
Bonr gum, p^yperidge
Persinunon
White ash
Baasafras
Slippery elm
White elm
Sycamore, Buttonwood
Butternut, white walnut
Black walnut
Bhellbark hickory
Pignut
White oak
Bedoak
Black oak
Chestnut
Beech
Canoe birch, paper birch
Cottonwood
White cedar
Bed cedar
Cypress
White pine
Spruce pine
Long-leared pine. Southern pine . . .
Whfte spruce
Hemlock
Bed flr, yellow flr
Tamarack
Tranarerse
Compression
Tests,
Parallel to
Modulus of
Grain, pounds
Buptnre.
per sq. in.
Mln.
Max.
Min.
Max.
7440
12060
4660
7410
6860
11766
4160
6790
6790
11680
8810
6480
9680
20180
7460
9940
6610
18460
OOIO
7600
12900
21780
8880
11940
8810
16800
6880
9120
7470
11180
6680
7080
10190
14660
6260
0400
9680
14600
0240
7480
18B00
16890
6660
8060
6060
1680O
4620
8880
6180
10160
4060
6970
10220
13062
6000
8790
8260
16070
4000
8040
6720
11800
4800
7340
4700
11740
6480
6810
8400
16320
6040
8860
14870
2ono
7660
10280
11660
19480
7460
8470
7010
18860
5810
9070
9760
18370
4860
8070
7900
18420
4640
8660
5060
12870
3680
6660
16860
18840
6770
7840
11710
17610
5770
8600
8300
18430
3790
6610
6810
9630
2000
6810
5640
16100
4400
7040
9580
10090
6000
7140
6610
11630
8750
5O0O
8780
10900
2680
4680
9230
21060
4010
lOOOO
9000
11660
4160
6300
7600
14680
4600
7420
8220
17920
4880
9800
10060
16770
6810
10700
(
131S FOUNDATIONS AND STBOCTUKAL MATEBtALS.
''ill^!l§§lllil!lliililiiiili!i
5ISp8i?l?83S§|ss??«||?S55|S« I
|||||lg|;§|ll|||||||||||||||||
iiiliHIIIIiiiiliiiliiiilililil I
!lli!!ilil!i!iiiilliiiiiiiill!'!
H —.^ e d e ^ e e e ^ d e e d ^ ei^d d d CI ti o^ei d
iSSiaSp^S^iis^^^^pS^iSSEiS
l!!iil!ili!liiiii*lilii!lii
iliiilliiiiiiiilllliliiiii
l!l|€3<8]tSS£333piS|«S!;iEI
9«ooQddde>i5oddddd fid^OQo '
»S=SSSS££:S38saScSS8CSSS {
WOOD. 1819
S17J.K — TQjkkd the wfe wn^formlp dUirihuted load in torn f<ff vhlto pine
or sprace beams, multiply thejavmber glTonixi th« -above table by the tmok-
nesa of the beam in incxxes. For beams of otiier wood, multiply also by the
following numbers :
'White Oak. Hemlock. White Cedar. Yellow Pine. Chestnut.
1.45 .99 .00 IJSO 1.06
f^mvlsB for iriiite «»1b« Bea
Subject to vibration from live loads.
10 = safe load in j>ouDds, less weight of beam.
I =: length of beam in inches.
d = depth of beam in inches.
b = breadth of beam in inches.
JFor a beam fixed at one end and loaded at the other:
1000 M*
tr=: 5 — .
el
For a beam fixed at one end and uniformly loaded :
1000 6d*
Jf\or a beam eupportedcU both ends and loaded at the middle :
2000 MS
to = ; •
For a beam supported cU both ends and uniformly loaded :
4000 M«
10 =
31
NOTB.— In placing very heavy loads upon short, but deep and strong
beams, care should be taken that the beams rest for a sufficient distance on
their supports to prevent all danger from cmshing or shearing at the ends.
Ordinary timbers crush under 6,000 lbs. per square Inch. Xq assure.a saf^y
of beam against crushing at the end, divide half of the load t>y iOOO : the
quotient will be the least number of square inches of base that should be
allowed for each end to rest on.
Xssble of Safo I<oad for Moderately Seaaoaed Wlilte Plae
Atrata or Pillars.
The following table, exhibiting the approximate strength of white pine
struts or pillars, with flat ends, is outllnea and interpolated from the rule
of Bondolet, that the safe load upon a cube of the material being regarded
as unity, the safe load upon a post whose height is,
12 times the side will be
24 ** ** •*
4g <l t4 II . , m i
60 *• " " *.'.!'.!'.!'.!! A
72 " " " jf^
700 pounds per square inch is assumed as the safe load upon a cube of
white pine.
The strength of each strut is considered with reference to the first-named
dimension of its cross section, so that if the second dimension is less than
the first, the strut must be supported in that direction, to fulfill the condi-
tions of the computation.
The strength of pillars, as well as of beams of timber, depends much on
their degree of seasoning^ Hodgkinson found that perfectly seasoned blocks
2 diameters long, required in many cases twice as great a load to crush
them ss when only moderately dry. This should be borne in mind when
building wiUi green timber.
!
d
1320 FOUNDATIOKS AND 8TBUCTUBAL MATB&IAXft.
X. BmfB ]Mairib«to«
itiMil
(G. J. H. Woodbnrj.)
fif the loAd la conoeninted at the center of the span, the beams wiU
in half the amount as glren in the table.)
•
1
Depth of Beam in Inches.
«
1
2
3
4
6
6
7
8
'1
10
11
12
13
14 15
If
Load in Pounda per Foot of Span.
6
38
86
164
240
346
470
614
778
900
6
27
60
107
167
240
327
427
640
667
807
7
20
44
78
122
176
240
314
387
480
593
706
828
8
16
34
60
94
136
184
240
304
376
454
540
634
736
9
27
47
74
107
146
190
240
296
360
427
501
581
687
»
10
22
38
60
86
118
154
194
240
290
346
406
470
MO
6M
11
32
60
71
97
127
161
196
240
286
336
380
466
801
12
27
42
60
82
107
135
167
202
240
282
327
STB
4S4
13
36
61
70
90
116
142
172
206
240
278
390
311
14
31
44
60
78
99
123
148
176
207
940
876
31ft
16
27
38
62
68
86
107
129
164
180
900
MO
9»
16
34
46
60
76
94
113
136
168
184
211
219
17
30
41
63
67
83
101
120
140
163
187
217
18
36
47
60
74
90
107
126
146
167
IM
19
. .
43
64
06
80
96
112
130
IBO
no
20
38
48
60
73
86
101
118
138
01
21
44
54
66
78
92
107
132
09
22
• •
60
60
71
84
97
119
07
23
• •
46
66
66
77
80
HI3
llf
24
. .
■ •
•
•
60
60
70
83
94
10?
26
• •
• •
46
66
66
75
86
m
t
]Natra>«t«4
llcft«B« to
ijmdard IfftaiU of
(0. J. H. Woodbury.)
•
Depth of Beam in Inches. 1
§.
2
3
4
6
6
7
8
9
10
11
12
13
14
15
16
11
Load in Pounds per Foot of Span.
6
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
26
3
2
*2
7
5
4
23
16
12
9
7
6
44
31
23
17
14
11
9
77
53
39
30
24
19
16
13
11
122
86
62
48
38
30
26
21
18
16
14
182
126
93
71
56
46
38
32
27
23
20
18
16
260
180
132
101
80
66
54
46
38
33
29
26
22
20
18
247
181
ISO
110
89
73
62
63
46
40
36
31
27
25
22
20
• •
• •
■ •
• •
241
185
146
118
98
82
70
60
63
46
41
37
33
30
27
24
22
■ •
•
240
190
154
127
107
91
78
68
60
63
47
43
88
86
32
29
27
26
306
241
196
161
136
116
100
87
76
68
60
64
40
44
40
37
3ft
31
301
2ft4
202
169
144
12ft
106
96
84
76
68
61
66
00
46
42
88
300
948
208
178
153
133
117
104
93
83
18
68
62
87
69
48
301
963
916
186
162
147
196
112
101
91
83
75
69
OS
68
jam
jOOS
jam
jOW
jQon
.1200
.145S
.ITS
.aoss
.2961
jaan
jam
•ooBo
.4339
.4800
jm
.6806
.6M8
.mn
MA.80KBT.
1321
Briok-Work.
Brick irork i« MuexmUy meMured by 1000 briokt lAid in the wall. In oon-
wquenee of TarUtlonB in siae of brick«, no rule for Yolume of laid brlok oaa
be exact. The following aoale is, however, a fair average.
7 common bricks to a super, ft. 4-inch wall.
14 •» " " •* 9-lnch "
M " •* u i« is-inch "
as •* " ♦• «• Ift-inch "
35 " " ** *• 2S-inoh **
Comers are not measnred twice, as in stone-work. Openings over 2 feet
sqvflkre are deducted. Arches are counted from the spring. Fancy work
sounted li bricks for 1. Pillars are measured on their face only.
One thousand bricks, closely stacked, occupy about 66 cubic feet.
One thousand old bricks, cleaned and loosely stacked, occupy about 72 cu-
bic feet.
One cubic foot of foundation, with one-fourth inch joints, contains 21
bricks. In some localities 24 bricks are counted as equal to a cubic foot.
One superficial foot of gauged arches requires 10 bricks.
Stock bricks commonly measure 8| inches by 4i inches by 2| inchesr and
weigh from 5 to 6 lbs. each.
Paring bricks should measure 9 inches by 4^ inches by 1} inches, and
veig^ about ^ lbs. each.
One yard of paving requires 36 stock bricks, of above dimensions, laid flat,
or 62 on edge; and So paving bricks, laid flat, or 88 on edge.
The following table gives the usual dimensions of the bricks of some of
the principal makers.
Description.
Inches.
Description.
Inches.
Baltimore front .
Philadelphia front
Wilmington front
Trenton front
Croton ....
Colabaugh . . .
}
8JX4JX2|
8^X4 X2|
3x81x21
Maine . . .
Milwaukee .
North River
Trenton . .
Ordinary . .
|7lx 3lx
18 XHx
M.« Tiwuir I Valentine's (Woodbridge, N. J.)
Fire Brick - J Downing»s (XUentown, T
Fa.)
8} X 41 X 2^ inches
9 X 4| X 2^ inches
7b aympute the number of bricks in a square foot qf wall.— To the face
dimensions of the bricks used, add the thickness of one -joint of mortar, and
multiply these tcMgether to obtain the area. Divide 144 sauare inches by
this area, and multiply by the number of times which the aimensiou of the
brick, at right angles to its face, is contained in the thickness of the wall.
SxAM PLB. — How many Trenton bricks in a square foot of 12-inch wall,
the Joints being \ inch thick ?
iqpj X W+l — 20-62 -, 144 -^ 20.62 = 7 ; 7 X 3 = 21 bricks per square ft.
(
1322 FOUNDATIOlfS AND 8TBUCTUBAL MATERIALS.
Orofls
Tom.
Pomidt.
Gtt. ft.
1
2240
22.4
0.M464
100
X
2.23
6000
60.00
2.4
5376
63.76
2.02
6872
68.72
2.88
0451
64.51
by itself.
Komber of Bricks,
G. Brick.
448
20
1000
1075
1130
1240
inwaU with
C. Brick.
381
17
860
914
lOOO
1100
One perch of stone is 21.75 cubic feet.
In New York City laws a cubic foot of brick-woik is deemed to
115 lbs.
Building-^tone Is deemed to weigh 100 lbs. per cubic foot.
The safe load for brick-work according to the New York City Lavs Is
follows:—
In tons per superficial foot,
For good lime mortar 8 tons.
Fbr good lime and cement mortar mixed . 11^ tons.
For good cement mortar 16 Ums.
"SK
intlmato Crsahlar-Iioad tn
ck for liilcica, fttoaea, Bloflttsra,
CeHi«8sta.
Brick, common (Eastern)
Brick, best pressed
Brick (Trautwiue)
Brick, paving, ayerage of 10 yarieties (Western)
Brick-work, ordinary ,
Brick-work, in good cement
Brick-work, first-class, in cement ,
Concrete (1 part lime, 3 parts grayel, 3 weeks old) ,
Lime mortar, common
Portland cement, best English,
Pure, three months old ,
Pure, nine months old
1 part sand, 1 part cement,
Three months old ,
Nine months old ,
Granites, 7750 to 22,750
Blue granite. Fox Island, Me
Blue granite, Staten Island, N. Y
Gray granite, Stony Creek, Conn
North Blyer (N. Y.) flagging
Limestones, 11,000 to 26,000
Limestone from Glen's Falls, N. Y. ...
Lake limestone. Lake Champlaln, N. Y. . .
White limestone, Marblehead.O
White limestone from Jollet, 111
Marbles,
From East Chester, N. Y
Common Italian
Vermont (Southerland Falls Co.)
Vermont, Dorset, Vt
Drab, North Bay Quarry, Wis ,
10000
12000
770 to
7150
300 to £00
450 to mo
930
770
3780
M80
45S0
12000
14875
22250
15750
13125
12000
11475
12«75
12960
112S0
10780
7612
meOZLLANEOTTS HATBRIAU.
tkudatonn
BruwD, Little Fa]l«.M.T
Brown. MiddlsUiwn, Conn
Bed. Haver»tr«w, N, Y
Bed-brown. Seneca Ireettone, Ohio ....
FremWinB, Dorcliester. N. B
LdDgmesdow ■■□diluDe, Springfield, Maa. •
Inebe*.
Ponndi.
ItWllM.
PonndB.
i„h..
,
am
2.31
e.si
Welrb* »t BkM
A»d B«r Bn
>aa.
Thick-
Sheeta
Thlok-
SheaU
lneh««.
" lb..
if"
1^'
^
HJX,
RoIIMI Br«.
■.
Trade Name.
Copper.
Zln,,.
m,.
i„»i.
Nlekel.
Cartridge bran '.'.'.'.'.'.'.
m
60
«0
40
a
:::
■it'
.s=
BS~ ':■]■■'■■
?C.Sro,.;.".,i.i.:::
18'
I
MISCELLANEOUS MATERIAL.
1325
Ohabooal Bopb. For Ship's Riggtng and Ouys for I>errio1u.
a 9
j« o
^es
IS
22
21
19
16 r
14
12
10
»
8
6t
1^
"III
vSeoQ
11
1(4
10
9^
9
8^
8
6
43
40
36
33
30
26
23
20
16
14
12
10
9
ss
I5
IP
(itoeblter*)
Gomposed of f StnuMto and a H«iup Center, 7 Wlree to the Strand.
SWEDISH UOH.
Trade
Number.
11
12
13
14
16
IMameter
in
Inches.
16
17
18
19
20
21
22
23
24
25
t
Approxi-
mate Clr-
comfer-
ence in
Inches.
?
V
WeijBTht
per Foot
in Poonds.
3.66
3X0
2.46
2.00
1.68
1.20
0.80
0.75
0.62
OJSO
0.39
0.30
0.22
0.16
0.125
Approxi-
mate
Breaking
Strain in
Tons of
2,000 Lhe.
84
29
24
20
16
12
0.3
7.9
6.6
6.3
4.2
3.3
2.4
1.7
1.4
Allowable
Working
Strain in
Tons of
2,000
Pounds.
6.80
6.80
4.80
4.00
3.20
2.40
1.86
IJBS
1.32
1.06
0.84
0.66
0.48
0.34
0.28
Mini-
mum Sise
of
Drum or
Sheare
in Feet.
4
CAST STEEL.
11
12
13
14
15
16
17
18
19
20
21
22
23
24
•1
3
3.66
3.00
2.46
2.00
1.58
1.20
0.89
0.75
0.62
OJK)
0.30
0.30
0.22
0.16
0.126
68
68
48
40
32
24
18.6
15.8
13.2
10.6
8.4
6.6
4.8
3.4
2.8
13.6
11.6
9.60
8.00
_6.40
4.80"
3.72
3.16
2.64
2.12
1.68
1.32
0.96
0.68
0.56
3
a
w
1326 FOUNDATIONS AND 8TBUCTUBAI1 MATESIALS.
Compoeed of 6 Strands and a Hemp Canter, 19 Wires to the Strand.
BVBDISH IBON.
i
9
1
2
8
4
6
6i
6
7
8
9
10
1^
10}
10r>
106
lOc
lOd
u j
II
S
6
4
3i
3
2
Weight
per Foot in
Lbs.
1195
9.85
8.00
6.30
4.85
4.15
ZXA
3^
2.4S
2.00
li»
1.20
0.89
aQ2
04K)
0.39
0.90
0.22
0.16
0.10
Ap.
Breaking
Strain
in Tons
of
2,000 Lbe.
114
95
78
82
48
42
36
31
25
21
17
13
9.7
6.8
5.5
4.4
3.4
2.5
1.7
1.2
I
Allowable r,.
Working p'*""^
Steain in -**
Tons Drum
of 2,000
Lba.
22.8
183
15.60
12.40
9.60
8.40
7.20
4.20
8.40
2.60
1.94
1.36
1.10
0.88
0.68
oa»
0.34
0.24
Sbesve
in Foot.
16
15
13
13
10
7
i|
6
4
%
S
U
1
i
CAST STBBU
i
1
2
3
4
5
5i
6
7
8
9
10
ij
10}
lOa
106
10c
lOd
5
4
3*
2
1}
11.96
9.86
8.00
6.30
4.85
4.15
3.56
3.00
2.46
2.00
1.58
1.20
0.80
0.62
OJW
0.39
0.30
0.22
0.16
0.10
190
166
124
96
84
72
62
60
42
34
26
19.4
13.6
11.0
8.8
6.8
6.0
3.4
2.4
46.6
81.2
24.8
19.2
16.8
14.4
12.4
10.0
8.40
6.80
5.20
3.88
2.72
2.20
1.76
1.36
1.00
0.68
0.48
10
\
8
7}
4
3j^
1
\
STEA9C BOILSBS. 1327
., 8TBAM.
IPotato to It«ni«iiib«r in flelectlnir a Holler*
(a) Suitability of famace and boiler to kind of fuel.
Iby Efflcienoy as to eraporativo results,
(o) Rapidity of steaming Ineluding
[I.} Water capacity for glTen power.
Water surface for ^ven power.
M
(d) Steam keeping q^oalities.
(e) Safety from explosion.
CjT) Floor gpaoe required.
(ff) Portability, and esse with which boiler can be removed when old, fox
replacement by a new boiler.
(A) Amount of, ease of, and rapidity of repairs.
(i) Simplicity and fewness of parts.
Q*) Ability to stand foroiiiff in case of necessity.
<sr) Price, inolnding cost of freight and setting.
(/) Durability and reliability.
(«»> Base of cleaning and inspection both inside and outside.
(h) Freedom from excessive strains due to unequal ezpanMoB and ability
to withstand same.
(o) Efficient natural circulation of water.
(jp) Absence of Joints or seams where flames may impinge.
For central stations it is necessary to arrange for a number of boilers
rather than one or two large ones. The size of unit adopted will depend
to some extent on the character of the expected load diagram. With a
number of boilers the cost of the reserve plant is reduced, tnough beyond*
tay six, there is less object in increasing tne number on this account.
norlBO«t»l Jietitra TobMlstr. >- More generallv used in United
States than any other. Fire first passes under the shell, returns to front
through tabes, thence up the chimnejy, except In some cases gAses are aoain
returned over top of the shdl. Ximited as to siae and pressures carriea by
reason of external tiring.
1VMtor*it«l»e. — Very largely used where high steam pressures or
■af etv from explosion are desfiafle. Fire passes Abcfot the exterior of tubes
and in most oases under about one-half the circumference of the steam
drums. Can be built for any size or pressure. Tubes are generally placed
in a slanting position, from one set of headers to another, as in the Babcock
ft Wilcox, Heine & Co. ; or vertically, as in the Sterling and Gahall.
Verttcal Wiwm Xobe, -^ Used considerably in New England. Spe-
cial design by Captain Manning; tubes 15 feet long 2^ iaohiM diametsr,
arranged in vertical shell with large combustion chamber surrounded by a
water leg. Gases mingle in combustion chamber, and In passing throngh the
long narrow tubes give up nearly all the heat, practieabiy leaving flue gases
4EtP to 500<^ F. By controlling height of water, steam can be superheated.
Can be built for high pressures andof large else.
oirt^v5i*w *«rt?>f HiSllora. *- Not much used for electrical purposed.
Shell of tWclc material, short in length and large in diameter. Parnaoes
*"iS^ * ' ^'*^ return tubes from combustion chamber to uptake.
1 "iru%^ *rS **^® cgWmfcr boUer, of small diameter and considerable
length (20 to 36 feet). Fired externally, and gases pass under full length to
chimney Flue boiler. ht» two or three large tubes mnsingfull IsDgth of
shell, which is long and of small diameter. Fired externally under the shell,
gases return through the flues to uptake. Neither of these types is now
used for electrical purposes.
Vlie Homo-Powor of fttoaai Bollor.
The committee of the A. S. M. E. on «* Trials of Steam Boilers in 1884 »•
(Trans., vol. vi. p. 286), discussed the question of the hon^itower of boilers :
1328 STEAM.
The Committee) A^.M.B. see Tnuu. toI. zzl.) •Pprrwrce the •
the 1886 Code to the effect that the standard " unit of evapocatloB '
he one ponnd of water at 213° F. eraporated into dry steam of the
temperature. This unit is equivalent to 905.7 British thermal anits.
The committee reoommenus tliat. as far as possible, the capaeitj of »
holler be expressed in terms of the ** number of pounds of water eraponSsA
5er hour from and at 2Vi9." It does not seem expedient* however, to ahs»>
on the widely reoognUed measure of capacity ox stationary or land boQsis
eiLpressed in terms of ** boiler horse^power."
The unit of commercial boiler horse-power adopted by the Oomadttasef
1886 was the same as that used in the reports of the boiler testa made as Ihm
Centennial Exhibition in 1876. The Committee of 1886 reported in favor «<
this standard in language of which the following is an extract :
** Your Committee, after due consideration, has determined to afleepttts
Centennial standard, and to recommend that in all standard triab the cam>
merclal horse-power be taken as an evaporation of SO poonda of „ .^
hour from a feed- water temperature of fOO^ F. into steam at 10 pounds gaq^
pressure, which shall be considered to be equal to 94^ unite of ev;i4>orasiaa;
that is, to 944_ pounds of water evaporated ftom a feed-water teminr-
ature of 212° F. into steam at the same temperature. This atandara ■
equal to 33,306 thermal units per hour."
The present Committee aocepts the same standard, but reTeraea the ofder
of two clauses in the statement, and slightly modifies them to read as foUov* :
The unit of commercial horse-power developed by a boiler shall be tafcm
as 34 units of evaporation per hour ; that is, te pounds of water eTaporatad
per hour from a feed-water temperature of 21^ F. into dry steam of titas
same temperature. This standard is equal to 33,317 British thermal mriti
per hour. It is also practically equivalent to an evaporation of aOpooadi
of water from a feed-water temperature of 100° F. into steam at 70 poondi
gauge pressnre.<>
The Committee also indorses the statement of the Committee of UK eoa-
coming the commercial rating of hollars, changing somewhat its wording, m
as to read as follows :
A boiler rated at any stated capacity should develop that eapaelW whas
using the best coal ordUnarily sold in the market where the boiler is loeatelt
when fired by an ordinary fireman, without forcing the fires, while exfalMb-
Inff ffood economv ; and, further, the boiler should develop at least eas-
tUra more than the stated capacity when using the same f uu and operated
by the same fireman, the full draft being employed and ttie Aires beiBg
crowded ; the available draft at the damper, unless otherwise imdentooa,
being not less than | inch water oolumn.
Heatlur Swrface •f Bellei
Altliough authorities disagree on what is to be ooosldered the hosHwf
surface ^ boilers. It is generally taken as all surfaces tiiat transmit best
from the fiame or gases to the water. The outside surfsee of all tabes is
used in calculations.
Kent gives the following rule for finding the heating surface of
l^eracsl V«l»«lsftr JMlleva. — Multiply the circumference of tbm firt-
box (in inohes> by its height above the grate. Multiply the combined cire«»-
f erence of all the tubes by their length, and to these two products add the ares
of the lower tube sheet ; from this sum subtract ^e area of all the tubei,
and divide by 144 : the quotient is the area of heatlngsurfoce in square feet
HoriaoAteil lt«t«r« Talrater Bellews. — ^Thrlstie). Multiply the
length of that part of drcnmf erence of the shell (In inches) exposed to tts
fire oy its length ; multiply the ctroumftrrenees of the tubes by their nnm*
her, by their length in inches : to the sum of these products add two-thlidi
of the area of both tube sheets less twice the area of tubes, and divide the
remainder by 144. The result is the heating surface in square feet.
Vi^mUmf ft«rface of THl»ea. — Muuiply the numner of tubes by the
diameter ofa tube in inches, by Its length in feet, and by .9618. l%e maat'
eter used should be that of the fire side of the tube.
* According to the tahUs in Porfer'i 7Veafis« en the Richanis Steam JEto-
gine Indicator^ an evaporation qfSO ponnde <^v)aterfrom lOV* F, i«A> ftam
at 70jnounds prtssure i» equal to an evaporwon of 34.488 panndafram ami
at 212^ : and an evaporation of 34^ pounds finom and at 2i2^ F. is eqnaai l»
30.010 pounds ftrom 100^ F. into Btetan at 70 pounds nreuure.
The ** unit of evaporation " bei$iff fouivalent to 965 J thermal mtifi, tkt
oommercial hone-power = 34.6 X 965.7 = 33^17 thermal aaiiCs.
STB AH BOILKBA.
Aiwa »r «u
Tblala oomiaoalT sUted In BrKllalo the grMa am. Ur. Bkrroi UTitlw
ilghest efflclaney for iuitbrscll« coal, vh«a buralng 10 to 12 Ibt. per Bquue
oot of grsM per bour. Isvlth tabeiTeftfto A of gnte ■nrfiue ) uultoiion
loml the tube arvk gtiould be | to f of tbs grmla ftonaoe-
Otber rulea In coiDimin lue tn to make (be •»» oTsr bridga walli »or
wrlHHiUl retDTD tubulki boilen)f the gnte Boifue ) tube uaa 1 mud cblm-
iayitrem|.
Alr-a|MK!« tB «nitH. — OgtulprMtlce[i30« to ao%tn»ot gnte tar
itr epKe. ir fuel cllnksn siuilT. lue the Urseit ilr ipMe knlUbl*.' With
oallree fromallnker amallerkfr ipace nny be need.
W««wc«i b«itw«wrM ■7sdt>r MM* »f B^Ier aMI Xa* af Crate.
rFor HnriionUI TobnUr Boiler.)
Ttor BiitbntdM sobI this ihoald be 34 inches for the Urgai iliea, *Dd eau
■ M iDche* for the anikller ilie*, aach u pen, bockwheit, and lioe. Vor
itamlnoni MuUi non-aking. the gnia fhould be abont 30 InchM below the
mtlKT, and for fatty or gaieniu rohIi rrom 36 to W iDobei. For ararace
EtaiouioiHixiala thedliMneecan be 36 Inchee. Anthraotla and bltamlnoaa
baU eanoot be eoonotnlcally bamed in the same famaoa.
I atvaia Bollvr BMUaacj.
ItIm ratio of (he heat nnlta otlllied In maklnB (team In a boiler, to llie
tl heM nDiti In the ooal oaed U called the •ffleleiie j of the boiler, and 1*
Malb
ntiaiDptretmt. For aiunpla, Uis hoaUns tbIim ot giMd ntkiadM <al
It Bbout HMO B.T. lJ.,aiiai[IU uvsporMc from *iul Kt 31»> UltiL «M«
(It^XKI -r MQ- If ■ >»U« <u"lw t<ft anponEM 13 lbs. nter pai ixnlid id
eorabutlbla, Un e&cienoj will ba
tAlnotl, bill poMlbls ui
— aat, > Bgan t
_.,.__ r ■peclkl ooDdlUau. nis hantliic tbIus irf bUuu-
uuui utmU Tula* SO muclL that It !■ neoiSBVj to dsMnaine It bj ■ enl
calorUuBMr before it 1» poHiblo to dotormiuD toe boiler efflclaaej*
Mnnglh ** BlveM* •kail.
(Abrid(«d from Bur on " Boilen ud Fuinmow.")
WlOTWhUnin boUar-plMe* (boold BTense tB,aOO Ibe., ud mUdMedHjM
lli<.,l«ialle*treiiatb.[iai ■qnue Inoli ot kcUodi bat (be giuM elrsutk <(
pbiM li li Ml I Mill Dj (be ■oiumit whlota baa bees Ukau onl of it tot Um bMT'
Uon ol riTeta.
Tbe foUowliie
Ttretod uul trip ^ _
feelor ot Mletr being G. The t „ — „■-.
ta : UultlplT t«elber the tenille (Irangth of iha plate, the thIcknMe ot ik
plMelDpana afanliioh, iind CheanelenBioftha Joint (•eeBlTettnd: <>l^
the prodnet br ODe-half the dlamatec of the boiler muldplled b; Oa fKta
WariOar rraMira terCfUiMlHcd MMtl«*r*
FOeUr if Safety. S. (Bur.)
Jolnia, Doabln-RlTatod.
UIMU-
Mar
IBUu
Iron
Steal
Btael
steel
Suel
Shell,
Shell,
Shell,
Shell,
Shell.
ShdL
Iron
Iron
Steal
Iron
Iron
Sud
BiTeta.
BiTet*.
BlTsta.
BiTata.
BlTeta.
BhtB.
M
SI
Ill
Ill
100
IM
19
IS
«]
«
100
100
IDl
lis
133
UG
44
74
91
n
w
101
48
S4
IH
M
WT
in
138
U
c
8B
9S
m
«
M
«»
m
loa
»
H
t
7B
83
93
m
88
•«
1(B
»
81
88
»
02
101
'ii
07
77
81
a
7»
85
«
8S
te
H* '
88
04
K
IH
88
m
W
n
*
88
8*
KO
«e
78
88
80
81
loa
03
07
so
u
m
80
>w
TO
68
B
T
T8
31
87
81
WT
T
78
79
K
»
80
88
88
KM
Of
W
HT
^
STEAK B0ILBB8.
1331
it« for Cjriladrlcal SlielU
Ateam IBoUcni. (Barr.)
Butt Joints, Triple Biveted. Faebor of Sqfetjfi 6,
IMameier
Thick-
ness in
Iron
SheU,
Steel
SheU,
Iron or
Steel
Rivets.
Diam-
eter,
Inches.
Thick-
ness in
Iron
SheU.
Steel
SheU,
Iron or
Steel
Rivets.
Xnches.
16thfl of
an inch.
Iron
Riyets.
16ths of
an inch.
Iron
RiTets.-
4
108
134
6
te
102
36
6
136
165
70
7
97
118
6
161
197
8
110
134
4
102
127
9
123
151
38
6
128
166
6
80
99
6
162
187
72
7
94
116
4
97
120
8
107
181
40
6
121
148
9
120
147
6
. 146
.. 178
.
7
•• •90-
» 110
4
93
116
75
8
102
126
42
6
116
141
9
116
141
6
138
169
10
138
157
4
89
109
7
87
106
44
5
no
136
78
8
99
121
6
132
161
9
•111
136
4
86
106
10
123
161
46
6
106
129
8
92
112
6
126
164
9
103
126
6
101
124
84
10
lis
140
48
6
121
148
11
126
168
7
141
172
12
137
167
5
97
119
8
86
106
60
6
116
142
9
96*
117
7
136
166
90
10
107
131
6
93
114
11
117
143
62
6
HI
137
12
128
166
7
130
169
8
80
98
6
90
110
0
90
110
64
6
107
182
96
10
100
123
7
126
163
11
110
134
6
87
106
12
120
146
66
6
103
127
8
75
02
7
121
148
9
86
104
6 .
84
. JU)2
. 102 .
10 ,
94
116
68
6
100
123
• 11
104
127
7
117
142
12
118
■138
6
97
118
8
li
87
60
7
111
138
9
98
8
128
167
108
10
89
109
6
93
116
11
98
120
62
7
100
138
12
107
130
8
124
162
8
68
83
6
90
111
9
76
98
64
7
106
120
114
10
84
103
8
120
147
11
93
113
9
136
166
12
101
123
6
88
106
8
64
78
66
7
102
126
9
71
88
8
117
143
120
10
80
98
9
131
160
11
88
108
6
86
106
12
96
117
68
7
99
121
8
113
188
9
127
156
(
1332 8TBAM.
••fe W^rlclMr PraMwra r«r BUmll Pli
d = diameter of boiler in inches.
/*= safe worklDC pressure, lbs. per square inoh.
t = thicknees of metal in inches.
10 =: tensile strength of metal.
k = factor of safety =r 6 for U. 8. and 4.5 for Great Britadn.
P = *^^Ji^ <or single-riveted. For donble-rlTeted, add m%.
P=i
d X i' X 100
where the notation is the same as in U. S. rule, and B = perowitace of
strength of Joint as compared with solid plate.
A«l«a C^veralsv laapectlOB of JBolleiw Im
Thickness of sheet in parts of inch X strength of s«iam as obteined
by formnla A or B X nltimate strength of iron stantped on plates _
internal radios of boiler in inches x 5 as a factor of safety
safe working pressore.
Asife VTerkfaar PrMaw« for Wtmt Plsstoa.
17.0. Atatotoa.—
P = safe working pressure.
S = surface supported, square inches.
t = thickness or metal in slxteenthii of an inch.
i = constant for plates of different thickness, and for Tmrioos eeoA-
tions.
p = greatest pitch in Inches.
t X k
P*
A'= 112 for JL-inoh plates and less, fitted with screw siAy bolts and nvtiicr
plain bolt fitted with single nut and socket, or riveted bead sad
socket.
X= 120 for plates more than ^ inch thick, nuder same conditions.
AT = 140 for fiat surfaces where the stays are fitted with nuts inside andost.
JCz^ 200 for fiat surfaces under same conditions, but with waidier riTcted to
plate, washer to be one-half as thick as plate, and of a diameter |
pitch.
In estimating the strength of the longitudinal seams in the eylimlriesl
shells of boilers, the inspector shall apply two formulso, A and B :
( Pitch of rivets — diameter of holes punched to reoeire the rlTeto_ ^
'^» ( pitch of rivets
percentage of strength of the sheet at the seam.
(Area of hole filled by rivet x No. of rows of rivets In
ing strength of rivet
pitch of rivets X thickness of sheet x tensile strength of sheet "
percentage of strength of the rivets in the seam.
Take the lowest of the percentages as found by formabs A and B, aad
apply that percentage as the " strength of the seam" in the following for
mula, G, which determines the strength of Uie longitudinal
^
STXAM BOILKRS. 1333
H>> brmee or stay on marine bollen to haye a oreatar plteh than 10|
n4»lx68 on Are boxes and back oonnecllona. Plates nttod witn doablo^mgle
roos riretod to plate, and with leaf at least two-thirds thickness of plate,
aiifci depth at least one-foarth of pitch, aUowed the same pressure as plate
with washer rireted on.
HI mi Vstadto. — Using same notation as in U. S. rules :
4:« + l)»
S — 6
K = 1M for plates not exposed to heat or flame, the stays fitted with nuts
and washers, the latter at least three times the diameter of the stay
and I the thickness of the plate :
K = 187 J( for the same condition, but the washers } the pitch of stays in
diameter, and thickness not less than plate ;
JiT == 20O for the same condition, bat doabling plates in place of washers, the
width of which is } the pitch, and thickness the same as the plate -,
K = 112.6 for the same condition, but the stays with nuts only ;
iC = 75 when exposed to impact of heat or flame and steam In contact with
the plates, and the stays fitted with nnts and washers three times
the diameter of the stay, and | the plate's thickness ;
K = 07 J^ for the same condition, bat stays fitted with nnts only ;
JIT = 100 when exposed to heat or flame, and water in contact with the
plates, and stays screwed into the plates, and fitted with nnts ;
JT = 06 for the same condition, bat stays with rlTcted heads.
W^mctxaitj mt ll«ll«r Plate. — U. S. Inspectors of Steam Vessels.
In test for tensile streneth, sample shall show reduction of area of cross-
•eotJon not less than the following percentages :
/ron.
46,000 lbs. tensile strength and under 16 per eent.
ForeachaddltionallOAt. s.np to 66,000 t.s. add .1
66,000 lbs. tensile strength, and above 26
i«
SUel.
All steel plates | inch thick and under 00 per cent.
" " ♦• {to} inch 46 "
•• " «* I inch and above 40 '«
JB«Uer Head Star*-
The United States Regulations on braces are : ** No braces or stays here-
after employed in the construction of boilers shall be allowed a greater
Btrain than OjOOO lbs. per square inch of section. Braces must be put in suf-
ficiently thick so that the area in inches which each has to support, multi-
plied by the pressure per square inch, will not exceed 6,000 when divided by
the eroes sectional area of tne brace or stay.
«• Steel stoy-bolts exceeding a diameter of i^ inches, and not exceeding a
diameter of 2^ inches at the bottom of the thread may be allowed a strain
not exceeding 8,000 lbs. per square inch of cross-section ; steel stay bolts
exceeding a diameter of 24 inches at bottom of thread may be allowed a i
strain not exceeding 9,000 lbs. oer square inch of cross section ; but no /
forged or welded steel stays will oe allowed. _ i
" xhe ends of such stay may be upset to a sufficient thickness to allow ^
for iming np, and including the depth of the thread. And all such stays
after belnig upset, shall be thoroughly annealed.'*
t»
1334
STBAM.
-I.— The followlnE tabl« !• given by Mr. Wm.M.
in ** Boilers and Fumaoes," p. 122. The working strength aasnmes aa
mate strength of 6000 lbs. per square ineh of section.
Diam-
eter of
Wrought Iron
Stays.
Inches smutre eaeh Braae wlH tapportiir
Pressures per Square Inch.
Brace
Inches.
Area
sq. In.
Working
Strength
Pounds.
75
Poonds.
100
Pounds.
125
Pounds.
IM
Poondi.
i
1
H
U
H
.60
.78
.99
1.23
1.48
1.77
3600
4712
5864
7362
8880
10620
7.0
7.9
8.9
10.7
11J»
6.0
6J»
7.7
8.6
9.5
10.4
5.4
6.1
6.9
7.7
9.2
43
&6
64
'A
&5
DiagroMAl
ealcttlaled separately.
Let
. — (** Boilers and Furnaces,** p. 129.) These matt te
Then
A = surface to be supported in square inches.
B = working pressure in lbs*
H=. length of diagonal stay in inches.
L = length of line drawn at right angles from snrfiMe, tobei^'
ported to end of diagonal stay la Inches.
S = working stress per square inch on stay in lbs.
a = area required for direct stay in square inches,
a, = area of diagonal stay in square inches.
7*= diameter of diagonal stay in Inches.
• — 4/ <*i — 4//< X B x~^.
" V .7854 f .7»4 8 X /"*
B =
.7864 X T*XSXL
AXH
Water tube and special types of bollen require special settings boS"^
controlled by local conditions, location of flues, etc., Mid cannot be tabontM
here.
The setting of horizontal retwm tubuiat boilers has become so luarif
standardized that the table following, taken In connection with the etfi.
will give all the general dimensions of brlck-wortc required.
For all special boiler settings, furnaces, etc., the reader la refined to^
makers of each.
STKAH BOII.BBS.
1336
BTBAK.
1
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jraoH 8 jo Bwoxo(qx
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1337
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W
ffr
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v>
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s
iai
ns
IS
ISO
9D2
...
30!
w
a?
3as
...
nn
t^<
?%
^1?
332
Hli\
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(K»
S8
100!
ai
1311
IIDI
1«M
.V»
1«T6
lii.e
M
1(W.
«ni
31 SB
nn
>«
S
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k
1314
2734
sax
JIM
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saw
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OHIlC2rBT8*
1839
The following table * will prore useful to those haring to do with eleetrie
iMtalLations, and givei the horse-power of chimneys to be used in power
Aants having verv efhcient enMnes, such as compound or triple expansion
Bginofl, when 2 lbs. of coal burned under the ooiler produce one horse-
lower at the engine.
ftlBe of ClUMaej for mtmmtm
(W. W. Christie.)
JBotlon.
1
Height of Chimney.
■
ISC
OO'
TV
80^
90^
lOO'
llO'
12^
leo'
175'
200^
226^
260^
300^
1
Horse-i
Mwer = 6.6 A^N. When 2 lbs.
coal burned per hour = 1 H.P.
18
21
27
30
33
84
110
144
182
228
f
92
(24
166
202
248
298
368
. .
1
98
130
170
214
206
326
384
448
626
104
136
182
228
286
344
410
482
564
7-28
• •
• •
196
248
806
364
436
614
602
774
862
1210
• •
• •
• •
■ •
818
384
466
640
624
820
1084
1274
1648
1840
• •
• •
« •
• •
482
666
062
868
1066
1338
1618
1924
2262
2620
■ •
• •
• •
- ■
• •
• •
• ■
• •
• m
• •
• •
• •
• •
• •
• • m
. . .
■ • •
• • •
38
614
604
702
916
1168
1430
1730
2102
2412
2802
3218
3690
4134
4628
• ■
• •
39
42
780
1020
1294
1604
1930
2294
2698
3126
3688
4062
4606
6168
6768
6382
7722
9192
48
• • «
64
1366
1600
2042
2430
2918
3306
8796
4322
4868
6468
6060
6748
8164
9718
00
6S
72
78
84
90
93
102
lOS
114
120
132
144
2184
2600
3048
3636
4062
4622
6214
6860
6614
7222
8736
10400
ini
3238
3760
4310
4902
6632
6202
6910
76S8
9262
11030
3412
3862
4688
6168
6830
6688
7286
8074
9764
11622
• « •
• • •
• • •
4380
4072
6662
6360
7166
7962
8840
lUVOO
12734
ChimMOjr ConatractloM.
A briok chimney shaft is made up of a series of steps, each of which is of
uniform tliioknees, but as we ascend each succeeding step is thinner than
Che one it rests upon. These bed Joints at which the thickness changes are
Ihd joints of least stability. The Joints and the* one at the ground line
are the only ones to which it is necessary to apply the formulas for deter-
mining the stability of the staok.
The nelght of the different steps of uniform thickness yaries greatly, ac-
cording to the Judgment of the engineer, but 170 feet Is, approximately, the
extreme height that any one section should be made. This length is seldom
approaohed eren in the tallest chimneys, as the brick-work has to bear, in
aadltion to its weight, that due to the pressure of the wind. The steps
■honid not exceed about 90 feet, unless the chimney stack is inside a tower
which protects it from the wind. In chimneys from 90 to 120 feet high the
•tops yary from 17 to 25 feet, the top step being one brick thick ; in ohim-
j
• **CSamneM Deiianand Theory," W. W.Chrittlf, D. Van Xontranfi Ownpawv.
twtaki niad tot thlmatjt.
Bond In ndU brlok woik>
1
CHIKNSTS. 1341
«ja from UD to 160 feet th«ttOM rarr from 96 to 86 feet: in ehimneyi from
10 to 200 feet the stepe Tary from 35 to 60 feet; in ehlmneys from 200 to
H> f e«t and over, the steps ym from 60 to 90 feet, the top step being one
ad ono-balf brioks thiek. The outside dimensions of a chimney at the
ttse ahould generally not be lees than one-tenth of the height of the stack
or sqoara chimneys: one-eleventh for octagonal, and one-twelfth for round,
rhe biittery may be ^ inches for every 10 feet.
The foondatlon of a chimney is one of the moet important points to be
onsidered. When this is upon solid rock it is only necessary to ezoarate
o a depth sufficient to prerent the heat of the gases from materially affect-
a the natural stone, and to secure the spread of the base. In cases where
mneys are to be built upon alluTial clays or made ground, it is necessaxr
10 ezearate until a good siilf clay, hard sand, or rock bottom is reachea.
the aiceaTation is fllled with concrete in Tarious wavs, or filled according
m the Judgment of the engineer, so as to economise material without
■idaagering the structure.
Babooek and Wilcox give the following formula for the ability of brick
shinineys to withstand wind pressure.
w = weight of ehlmney In lbs. (brickwork = 100 to 160 lbs.
per cubic foot.)
4i=: average diameter in feet, or width if square.
*= height in feet.
6= width of base.
jks= conetant, for square chimneys =66.
for round chimneys = 28.
for octagonal chimneys = 86.
c= k —^- and in = * -=— .
RsUU«l Hrlck Chtasaeja*
Another type of chimney now much used in the Bast, is built of radial
Vriek, perforated vertically with holes about \" square, passing entirely
t^ugn them.
The advantage of these bricks is said to be a better bond, as the cement
inakee a dowelln the perforations.
They are made of a special quality of clay, having greater care in the
msklng, are burned at a greater heat than the red bnok, and are said to be
of a more uniform grade.
Badlal brick chimneys as built in the Qnited States do not always have
Unlng, for the brick are supposed to be capable of withstanding the neat of
the gases usually met with, out in special cases a lining is built in them, and
it carried by the outer shell.
The less number of lointe to the weather is also given as a point in favor
of the radial brick chimney.
In making oomparisons of the costs of the several types of chimneys, if of
briek, they should have the same
I
height,
id
inside diameter,
lightning protection detail!,
ladder equipment,
I qualitv of workmanship,
Isame UMtor of stability.
\
r
1342
1
8TBAM.
Or»DI P«wer
for €«Bi
(B. U.Tburston.)
Draft of Chim-
Fuel.
ney in Inches
of Water.
FueL
Drafi is im
of Water.
Wood
0.20 to 0.75
Coal-dust
0.80 to LS
Sawdust .....
0.36 " 0^
Semi Anthracite coal
QM^ 1.S
Sawdust mixed with
small coal ....
0.00 '• 0.79
Mixture of breese and
slack
li»** IJI
Steam coal ....
0.40 '» 0.76
Anthracite ....
1J5** IM
Slack, ordinary . •
0.60 ** 0^
Mixture of breesa and
coal-dust ....
1J5- L»
Slack, very small . .
0.76 •• 1.26
Anthracite alack . .
L30-* IM
Heirlt« •€ CMaiM^y for ItamlBf OlveB Aaioute mi
Professor Wood (Trans. A. S. M. B., rol. xi.) deriTea a formala tnm
which he calculates the height of chimney necessary to bnm stated qna-
tity of coal per square foot of grate per hour, for certain temperatm d
the chimney gas.
Pounds of Coal per Square Foot Grate Ana.
Temp.
Outside
Absolute
Temp. Chim-
ney Qases.
16
20
21
Air
Helgbt of Chimney, Fee«.
«\-
700
67.8
167.6
3B0J
800
66.7
116^
172.4
1^
1000
48.7
168.0
149L1
1100
48.2
96.9
U8J
1200
48.1
100.9
ubjo
1400
61.2
106.6
IS9J
leoo
63.6
110.9
168J
So
2000
68.0
132A
9015
Rate of ConibastloM Oao to HotrUt of CMmmcj.
Prof. Trowbridge (" Heat and Heat Eoffines," p. 153) gires the foUowlil
table, showing the heights of chimneys for lutidtteing certain rates of «»
bustlon per square fooi of area of section of the cliimney. liie ratio of tM
grate to the chimney section being 8 to 1.
r
Lb8. Coal
Lbs. Coal
burned per
Hour per
sq. ft. of
Grate.
Lbe. Coal
Height
in Feet.
burned per
Hour per
sq. ft. of
Height in
I^t.
burned per
Hour per
sq. ft. Sec-
tion of
Lbe.CasI
benifd p«r
Hour per
Section of
sq. ft. Grata
Chimney.
Chimney.
26
68
8.6
70
126
16.8
30
76
9Ji
76
131
K.4
36
84
10.6
80
136
16^
40
93
11.6
86
130
17.4
46
90
12.4
90
144
- 1&0
60
106
13.1
96
148
18J5
66
111
13.8
100
182
19J
60
116
14.6
106
166
UjS
66
121
16.1
110
160
sojo
*
1
i
»
a.
1
Ontalde Wall.
1
11
1"
i!
^
^
No.
Brick.
Srp
u
w
«
7fl.6ln
1 «n«i
m,«»>
"""
S.UHJU
STs lonj t>«aii a»d In the Ic
lied orfldDrBbie BDd need no gn ji, tw tbe;
)d toabeOTjfouiidktlon. Th«y ure luiisllr
T« of QO ]b«- par BquAre Toot.
«■•■■ for H««l ClilMB«-7>
(8BlHt«d Irom ClrcDlftr of Philadelphia EoflnMrlDg Wotki.)
UALr^LlHRD CBIKBBrs.
(ei|bt. fe
It dlATnaterroDDdallon
•rick UbIbt for Strrl BMck*.
ItknHiigll Incbei *lr spue bet ween lUok and lining:
LIIouHde I IdoI> >lr >pue between atx
Brick* » X 4 y 2 Inches. Uld wtthoi
Lining 41nebe( (one brick) tbick :
Momeer of brieki per foot In dism
' Black, and par foot ot height
H^bt, tMuDOMr,
13 Mill 14
II ud 14
n and 14
UudU
11 ud 14
11 ud 14
Hud 14
IlKBdU
U3J»
an.oo
■l*w«n far P>p(«« DmmcM.*
Fonci DraMglU CapaeUy TbMc /or Btotrtrt.
TMnpantan It, « dMroM F.; U lb*, alt w 1 lb. oa<a ; SIS lk& i
ir H.P.i baroingtor, IBM; 334 gable ft. per t lb. eml; enpontlaa, U
■Mr par 1 lb. sottl; pr«Miir«, 1} oDoeoa; S lb*, ooal p«r H.P. bmr.
1
1
•s
1
jl
1
■s
1^
1-
i!
ft
5^
I!
fli
"1
,
4
J
3
™,
m
S
l!t
me
££
14»
- -
s
(Ameiisu Blovar Co.)
• Prom "FDrnuM Dn(t; lu PradaaUoB, bf Haohuikal M*aa**
FUEL.
1346
a
1^
eg
ss
•rll
8»
04
I
I
. lO
!
1
i
I*
an *«
a?
is
-I
s
'dmox ^o^ianquioQ
J9<I JiY 999 j Ofqno
i§§§§§i§r§§§§§
of « v« « « g sf 5 gf S5 a ff$
*Xj9qdiJ9j4«
qotti J9<nd[*H
eps!^^^;^!^^^^
'^jroqdpLO^
49a
!i§igi§i^ll§j|
Of '^H »TMff
i9d aofiuodBAa
IISIIIIIIIPII
spuno J g 9« inoH jod
moj;
i[4Io«d«o a9iioa -^H
f4 «-i «-i d ef CO ^ lO «D QO o c<
sisSISigSSim
«<4tM<-ie4M
'din9x *9)nn|j^ I9d
190jI oiqno
§|^|§i§l§§||§§
lO«D0»i
'9jvn1>s mqoni
•^©UnO JO **18
g§§§§§S§8§§S§§
s^s;ir?^9S8S^ss
•f9nii JO -ureid
SS)S89S89$Se8SS3SS
iloqdiMd 9« q9P(ii
M'i^^'SkSS.%^ti%t
•99qoui
SS9«SSSS!SS§§§|
'mj JO 9SfS
S8S8S8SS988;
1346
STBAM.
The effect of the temperature of the gases, on the
operate a fan, it shown very clearly by the following :
BCiaet of Veaipcratmre of
Indaoed Draft.
Draft In Inches of water
Temperature of gases at fan, degree F. .
Speed of fan, rerolation per minute . .
Current required bv fan motor —amperes
Current generated by plant — amperes .
Proportion used by tan —per cent . . .
Boiler H*P. developed . ,
1
S
0.42
046
l»J$
102.6
154.
17a.
10.3
XS.3
8Mw
1S9S.
1.16
1.17
621.7
0D0J8
fans), InelndlBg
The blower used was an Amerioan Blower Go.*s centrifagal tarn vlA
OB v^ BA Inn]) ivIiaaI
The third test, gases 130 deg. hotter than first, requires about 100 per s«t
more power, and yet the boiler eyaporation is about 90 per cent ^
the first test. — diirtit Pub. Co., by Davis & Grin.
The cost of the above Mechanleal Draft otttfiT(3
was fi6JS3 per boiler H J*.
All of the blower methods of draft production must be oonaldered In eaf^
neetion with, and be planned with especial renrd to, the quantity of fudto
be burned in a given nme, luid the amount or air needed for tbe eoiiplsli
combustion of we fuel, which air must necessarily pass through tiie blowaa
18 to 26 lbs. of coal per square foot of grate per hour is all the eoal thsl
should or can be burned with economy under natural draft; a|^iiiist<s sisiissl
necessitates forced draft.
Another thinff which should not be lost sight of in conneetlosi with (ke
burning of smau coals, is the unbumt eoal falling through the gFate,
in the case of anthracite culm has reaohed 66 per oent (found In the
Kiada «Mi lavr«dl«nta of r««la.
The substances which we call fuel are : wood, charcoal, eoal, eok% psst,
certain combustible gases, and liquid hydrocarbons.
Combustion or burning is a rapid chemical combination.
The imperfect combustion of carbon produces carbonic oxida iCQK ^^
carbonic acid or dioxide (CO|).
From certain experiments and comparisons Bankine conclndea •• that tte
total heat of combustion of any compound of hydrogen and carbon Is nesriv
the sum of the quantities of heat which the hydrogen and carbon eontaieei
in it would produce separately by their combustion (CH4 — nuush gas or
fire-damp excepted)."
In computing the total heat of combustion of a compound, it is cciifsa
lent to substitute for the hydrogen a quantity of carbon whlcn would give
the same quantity of heat ; this is accomplished by multiplying the went
of hydrogen by eW82 -^ 14600 = 4.28.
From experiments by Dulong, Desprets, and others, " when hydrogca sad
oxygen exist In a compound In the proper propootifm to form water (by
weight nearly 1 part H to 8 parts O), these constituents have no effect «b
the total heat of combustion.
" If hydrogen exists in a greater proportion, take Into the heat aeeocai
only the surplus.*'
Dulong's formula for the total heat of combustion of carbon, bydiega^
oxygen, and sulphur, where C, H.O. and 8 refer to the fractions cf «as
pound of the compound, the remainder being ash, etc. Let A r= total Isd
of combustion in B.T.U. per pound of compound.
* = 14600 0+62000 (at— ^] +4000 5. (AJS.M.E. Trans. voL xxf4
Bankine says : ** The ingredients of every kind of fuel eommonly used ■
be thus classed : (1) Fixed or free carbon, which is left In the fona of d
coal or coke after the volatile Ingredients of the fuel have beea dlstSlsd
away. These ingredients bum either wholly In the solid state, or part la
the solid state and part in the gaseous state, the latter part bebif iisK
dissolved by previously formed carbonic acid.
**(2) Hydrocarbons, such as defiant gas, pitch, tar, "^^K^ba, etc, aDsC
which must pass into the gaseous state before being buinea.
" If mlXAd iM tliBlr lint iMoIng tram mmoiigit the bnmlnB carbon Tlth ■
irfe quntttj of air, tbeae InBanunkble gua ue oompletel; bumed nith
ttanaparent blue lUmei prDdacInK carbonic acid and alAam. Wben ratoad
la red hoBt, or thenabODU, betore being mtiad *lih a BUlSeleat qiuuitllT
I air for p«n«t eombuatloii, the; dlaengsRe oarlxin In Hne poirder. ana
•H to th« ooodittoB panlj ol manh gaa, and panly or trea bTdrogen ; and
ke blgbar tha (ampMatnre, On grauat ■■ tbe proporMon of carbon tbni
■* IftEe dlMDgaged carbon la cooled below th« temperstnre of Iniition be-
gr« oomlni In ooo U«t with oijnn. It ooiutllnHe, while doatlBgln (he |U,
noks, knawben depoalted on aobd bodlM, toot.
*'Bnt U the dlaengag«d oar bonis maintained at tbotemperMDre of ignition,
Ad annillad with oivgeu laOlclent for Iti oombiwtlon. It bums while float-
Dg In (ho InflammaMo ga*. and lonn» red, jallow, or white flame. Tbt
tuna fRMU fad Ii the laigar tiia idots ilowlj Its oomboatlon ■■ effected.
"^OxTfeDOTb^ilnigualthwactiiallirtOnnliigwater.orexlitlng Incom-
ilnatioD wTth the other eonitltneut* In the proportlona which form water,
hull qaantmea ot oxTgen and h jdrogen aro to be left out ol occonnt In de-
ennlnlng tba heat gatiiiatod by the comboatlon. If th« qnantlijot water
ictoallr or vtrtnally praaont In eaoh ponnd of fuel l> so great at to make its
atent heat ot eraponition worth eouilderlng, that beat li to be deduciad
Irom tho total heat ot oomboitlon ot the foal. The praMnoe o( water or lu
nnatltiiania in tBel promotai the formation oE uooke, or of the oarbona.
laooa Oanie, whieh u Ignited imoka, aa the caae maj' be, probably by
UBchKnicallr ■weeping along flns partlclea of carbon.
"{4) Hitrogen.eitliarfieeor incomblnatlon with othercooatltnenti. Thi*
mbatanea ii almpir inert.
" (p) Sulphiiret ot lron,*wbleh axlata in ooid and la detrimental, an tending to
tauas BpontaneODe HHnbnatlon.
" (S) Other mineral oornpuiuidi of (arlona klndi, which are also Inert, and
ftnntbaaih left atter complete combiution ot thetnel,andalaotbecl[nk«r
or glaeey material prodosed by fiulon of the aah, whlob tends to ahoke the
The tollowlDg table girea tbe total heat aToWad by eonibngtlblea and their
Salraleat eiaporatlre power, with the weight of oiygan and Tolome of an
emlcally ODmnmed.
Pound ol C^'
boitlble.
1
III
23BI3
13648
ii
III
Iba.
Iba.
SiS.
M
Cubonlooilde . ~. . . . . '.
U^t Carbureted Hfdrngen . .
*iP«|t(eot
I» per cant mrfatuie . .
i
3.«
Z.iS
i:«i
II
J4.8
s.oe
ill
«39
78
33
m
m
M.a)
isioo
4.48
14J)?
11.38
».a)
4.17
r
1348
8TBAM.
^
i
I
s
9
o
9
S
• S
4 I
2
•o0KJ»O
ITOHOJOoqx'lBVifl VIA
8 :s SSS^SSS^
■^UQ ^ouaino RYlii
j • • J • ^» ^» ^^ _ ^
'9iai)mqaioo
JO punoj joqf cT povpu
J99«i^ JO spuno j n]
JO liddng i«0|)OJ09qx
9m wuiii TOjqx q*ui
II § g§§ii§§§
»« ^ *4 V^ Vi« Vi^ v^ "^ «4 w *•
•aiv JO iiddng i«oj
)0
s§lis
•j|y JO ifddns |«o)9M
-ooqx »q» 8»ai|i f I q«lM
)I0 lO
•JTV JO
llddng i«oi|ojooqx q»»M
•oiqiiflnqmop
JO pano^i jo^ flpunoa ai
11
1^ v^ V4«4v«
s ssssssssst
OiKolOe^
1
a
I
I
3
o
1 2|| . , ^,
^ fe
&• >
L
^
FU8L.
1349
TeaiiMratvre of Vlre«
By roferenoe to tbe Uble of oombnstiblee, it will be seen that the temper-
tf.iir« of the Are is nearly the same for all kinds of oombostiblee, under lim-
Oar oonditions. If the temperatnve is known, the conditions of oombnstion
nay be inferred. The following table, from M. PouiUet, will enable the
tempermture to be judged by the appearanoe of the Are :
Appearance.
Temp. F.
Appearance.
Temp. F.
Bed, inat Tisible . .
«• dull
** cherry, doll . .
full. .
" " clear .
91770
1290
1470
1660
1830
Orange, deep . . .
" clear . . .
White beat ....
" bright . . .
2010
2190
2370
2680
2730
T« det«raita« VeHspemtarv by
•■ ef Metola, etc*
Substance.
Tern. F.
Metal.
Tern. F.
Metal.
Tem.F.
Tallow . . .
Bpermaceti .
wax, white .
Sulpbnr . .
Tin ....
92°
120
IM
230
466
Blsmnth .
Lead . . .
Zinc . . .
Antimony .
Brass . .
6180
630
793
810
1660
SilTcr, pure . .
Qold, coin . .
Iron, cast, med.
Steel ....
Wrought iron .
1830»
3106
9010
2660
2010
AaserlcaB
Kind of Wood.
Hlokory — Shell bark.
White oak ....
Hickory — Bed heart
Southern pine . . .
Bedoak
Beech
Hard maple . . .
Virginia pine . . .
Bpmce
Kew Jersey pine . .
Yellow pine • . .
White pine ....
Value in Tons Goal.
Weight
per Cord*
Anthracite
Bituminous
4460
.606
jm
3821
JB2
.481
8706
JM
.467
8375
.460
.435
3264
.443
.41
8126
.426
.394
2878
JOl
.363
2880
.304
.338
2326
.316
.293
2137
.291
.289
1904
.260
.24
1868
.264
.235
^
1350
STEAM.
Goftl.
Per Cent
of
Ash.
Theoretleal YahH.
State. Kind of CoaL
In Heat
UnitiB.
Pounds flf
Water
Srap.
Pennsylrania. Aathmoite ....
. • . •
•* Cannel ..!!!'.
•* ConnollBville. . . .
** Semi-bitnmlnoiiB . .
** Stone's Gas ....
" Tooghiogheny . . .
" Brown
Kentucky. Coking
** Cannel
II 11 ^ ^
" Lignite !!.'!!!
IlllnolB. Bureau Co
" MeroerCo
•
«« Montauk
Indiana. Block
" Coking
** Cannel
Maryland. Cumberland ....
Colorado. **
II II
Texas. "
Washington Ter. "
Pennsylvania. Petroleum. ....
8.40
6.18
24»
15UB
6JS0
10.70
6X0
6.60
9.60
2.76
2.00
7.00
6.20
5.60
5JS0
2JS0
6.66
6.00
13.88
5.00
9.26
4.60
4JiO
3.40
...
14,190
13AI5
14,221
13,143
13,368
13,165
14,021
14,905
12,324
14,391
15,196
?;326
13,026
18,123
12,660
13,688
14,146
13,007
12,226
9,215
13,662
13,866
12,962
11,651
20,746
14.19
MjH
14.72
uu*
]4ja
14.71
12.S
1489
16.»
18JI
9M
13A
ISA
13.10
14J8
UM
ULBI
OM
9M
1401
149
13.41
UM
The weight of solid coal Taries from 80 Ibe. to 100 Ihs. per eublo foe*.
The Heatlnr Valac •# CMd^
On page 1361 are glren the results (^N«y , Journal of Bnaineeri%M) of fow
experiments made at Cornell Unlrersity with a coal calonmeter aeviMd^
Prof. K. C. Carpenter. It consists of two cylindrical chambers. In tbef
one of which the sample of coal is burned in oxygen. Tlie heated gasc
through a coiled copper tube about 10 feet long contained in the outer i
ber. The coil is surrounded by water which expands, the expansion
measured in a finely graduated glass tube, thus giring the heat unite ia ikt
coaL The calorimeter is calibrated by burning In it pure earbon. FoUov-
ing are the tables :
ifi
liiiiiiiiiiii
|li
iiiiliiiii
11
gsaslsisislssi
ifili
Sim
=i§i3a§ps
If
2!S23Sls!!l33
1 t?
iiiiliiiii
II
ililisSssilis
511
s6i!i!Si5?^l?
siiaiisssassa
\H.
iiamM
! ^
i«sS3«2=iSS
Ml
252§3§3SSS!35
1.1
iliiii^§il
1 i
1
5§SS3S53S3
&
i-
: :<
t
'f.
1
1362
STBAX.
(Power.)
Designation of Ck>al.
ANTHILIOITB.
Bearer Meadow, Penn
Peaoh Mountain, Penn
Lackawanna, Penn
Lehigh, Penn
Welsh, Walee
SBMI-AlfTHBJLCITX.
Natural Coke, Virginia
Cardiff, Wales '. . .
Lycoming Greek, Penn.
▲rkansM, No. 16 GeoL Surrey ....
SSMI-BITUXUrOUS.
Blossburg, Penn
Mexican
Fort Smith, Arkansaa
Cliff, New South WaleB.AustralU . .
Skagit River, State of Washington . .
Cumberland, Maryland
Cambria County. Penn
Mount Kembla, New South Wales, Aos.
Fire Creek, West Virginia
Arkansas, No. 12 Oeol. Surrey ....
BITU1CINOU8.
WilkesonjPierce County, Washington .
GowUts, Washington
New Birer, West Virginia
Pictou, Nora Scotia
Biff Muddy, lUlnois
Bellingham Bay, Washington ....
Midlothian. Virginia
Connellsrille, Penn
lUlnois, Average
Carbon Hill, Washington
Clover Hill, VirglnU
Wellington, Vaneourer Island, B.C. . .
FranklTn, Washington
Rocky Mountains
Newcastle, England
Mokihinui. Westport, New Zealand . .
Brunner Mine, Greymonth, New Zealand
Pittsburg, Penn
Nanaimo, Vaneourer Island, B.C. . . .
Hocking Valley, Ohio
Pleasant Valley, Utah
Kentucky
Ellensbnr^r, Washington
Olympic Mountains, Washington . . .
Scotch, Scotland
Ro8lyn, Washington
Cook*8 Inlet. Alaska
Kootznahoo Inlet, Admiralty I., Alaska
Liverpool, England
Calispel, Washington
Carbonado. Washington
Upper Takima, Washington
Methow, Washington
11
11
4
l^
E|
1.6
2.38
88.94
1.9
2.96
89il2
2.12
3.91
87.74
3.01
3.28
88.15
1.3
6.26
88.
1.13
12.44
76.06
1.26
12.86
81.9
.87
13.84
njsa
1.36
14J»
74.06
1.34
14.78
73.11
1.0
li.86
66.7
1.07
17.2
73.06
.86
17.7
71.8
1.19
18.8
71.66
.97
19.87
72.28
3.4«
3Dj53
69.37
1.3
20.83
66JNi
.74
22.42
76iS
.88
34.66
68.2
1.33
26.88
66.75
1.16
36.13
61.9
.67
36.64
70.66
3JJ7
27.63
66.98
7.12
7»A
64.64
3.98
29.64
68 J»
2.46
29.86
63.01
1.36
30.10
68.61
8J3
30.14
4&88
2.16
31.73
56.8
1.34
82.21
56.83
2.16
34.15
64.86
SJi
34.27
64.23
7JS6
34.66
42.86
IJi
34.7
69.3
3.96
34.94
67.9S
1j69
36.68
56.63
1.7
96.
66.
2.26
36j06
51.96
6.96
36wl6
61J)
6.43
37.73
48.40
2.
37.89
66.01
2.
39.1
64.4
6.1
39.16
47.01
3.01
38.19
48.81
3.1
38.7
62.66
1.26
38.87
49.89
3.74
37.02
46.15
.89
39.96
64.9
2.39
4L1&
43.92
1.8
42.37
63.11
1.2
42.47
62.31
2JS
43.71
48.37
7.11
6.13
11.38
4.
13.96
9.06
10.77
8.68
9.66
SOS
9J6
10.81
.8
16.26
6.04
10.09
1JS3
13.99
8.74
&
14.74
8.33
16.
10.31
lais
8.86
8.
UJ6
4.6
3.18
6.11
7.3
9.75
6.56
7.44
4.1
3.4
7.77
9.34
4JS6
7.82
14j09
4.62
13.21
3.82
4.13
4.36
a
A
JSS
M
4JB
■ • ■ •
IJ6
■ * • ■
.77
15
Tnoa
a0
Ji
.77
IM
M
jK
.78
5.
2J3
ja
SI
1.1
2JI
.67
L2S
....
1-1
Si
M
1.2
.n
J8
2
Traee.
TrsM.
^
FUEL.
1353
yr<MUgMif Aaalyrt* of Coal— QnnlimK/f.
Designation of CoaL
Newcastle, King County, Washington .
Black Diamond, KinKConnty.Wasnington
Blaok Diamond, Mt. Diablo, California .
MGXITSS.
Otago (Kaitancata Cr.), New Zealand .
QUman, Washington
Cooa Bay (Newport Mine), Oregon . .
Alaska
Huron, Fresno County, California . .
lone, Amador County, California . . .
S3
« ..
Sis
'sS
•
ou
2.2
ja
.3
is 14
M«r
flS
i^
<
2.12
46.7
43.9
7.15
3.11
47.19
45.11
4i»
14.09
33.89
46.84
4.58
W.61
37.26
38.41
3.73
4.8
47.07
37.19
10.06
15.46
41JS5
34.96
8.06
14.6
44.85
31.2
9.35
11.7
61.73
19.68
16.94
42JS8
34.88
17.42
5.12
•a
•a
OQ
.13
.01
.88
2J»
1.15
2.73
Trace.
iljsis of €)0iL9,
(From report of John R. Procter, Kentucky Geological Survey.)
Where Made.
Fixed
Carbon
Ash.
Sut
phnr.
ConnellsriUe, Pa. (Average of 3 samples) . . .
88.96
9.74
0.810
Chattanooga, Tenn. " "4 ** ...
BUM
16.34
1.606
Birmingham, Ala. " u 4 i* ...
87.29
10JS4
1.196
Pocabontas, Va. " «» 3 " ...
92.53
6.74
0.587
KewBlTer.W.Va. " " 8 •* ...
Big Stone Gap, Ky. " •« 7 «« ...
92.38
7.21
SSS
93.23
5.69
0.749
ti
II
II
II
II
II
II
II
Ifteqalrcd to Atow » Tarn (iKMO lbs.) of VMrloos
Kinds of Coal.
▲XTHBACITJB.
Welsh, Wal«« .'. 30 cubie f eet.
Peach Mountain, ^enn 41.6
Bearer Meadow, Penn 40.2
Lehigh, Penn 40.5
Ijaokawanna, Penn 45.8
SKMI-AITT H&ACITE.
Cardiff, Wales 38.3 cubic feet.
Natural Coke, Virginia 60.2 »» "
8XMI-BlTUMIl?OU8.
Cumberland, Virginia 41.7 cubic feet.
Blosabursh.Penn 42.2 " "
Mt. Kembla, Australia 37.7
Mexican 36.7
BITUMINOUS.
New River, Virginia 46 <
Wellington, Vancouver Island, B.C 41.8
Midlothian, Virginia 41.4
Neweaetle, England 44
Pioton, Nova Scotia 45
Scotch Splint, Fordel 40.7
Pleasant Valley. Utah 42.3
Sydney, N. S. W., Australia 47.2
l^ikasima, Japan fJ-J
PittBburffh. Penn *7.8
Liverpool, Ensland 46.7
Scotcn, Dalkeith 48.8
Carbon HiU, Washington 36.9
Clover Hill, Virginia 49.2
Rocky Mountain • 41.2
UGNITK.
/^laafcg, 41.8 cubic feet.
WOOD.
Dry pine wood 107 cubic feet.
(X)KE. — Coke from ovens, preferred to gas coke as fuel, weighs with
few exceptions about 40 lbs. per bushel. Light coke will weigh 33 to 38 lbs.
Heavy coke, 42 to 60 lbs.
11
II
<l
II
Ac
fee
It
II
II
II
II
II
II
.1
II
II
II
II
II
•1
II
II
II
II
II
II
II
41
11
11
II
II
II
^
1364
STEAM.
W«lrkte«rv«rl
Lehicb buckiHieftt .
" broken . .
" cupola . .
*• duat . . .
" «8K . . . .
*' lump . . .
•• nut . . . .
" pea ... .
" stove . . .
Free burning egg .
•' nut .
•• stove
Pftteburgh ....
lUinoie
Hookinc
Indiana Block . .
Erie
Ohio Ouinel . . .
Conndlaville ooke .
Lbs. per
cuble
Co. foal
pertai
foot.
ofSOOOAi
54.04
37.01
56.85
35.15
55.53
36.01
57.35
34.n
57.74
34.61
55.30
36.19
58.30
34.SS
53.18
37.66
58.15
34.3i
50.07
36.67
56.88
35.16
50.33
35.96
40.48
43.66
47.23
4S.3S
40.30
40.M
43.85
46.51
48.07
41.61
40.18
60.61
20.30
76.01
'«r«i6rkte per C«Mo Wmm/i^ C;«a1
Anth. eoal market siaee, looee
Anth. coal market siaee, moderatdy shaken . . .
Anth. ooal market siaes, heaped bushels
loose 77-83 lbs. . . .
Bit. coals, broken — looee
Bit. coals, broken — moderately shaken . . . .
Bit. coals, broken — heaped busheb 70-78 lbs. .
Dry coke
Dry ooke, heaped bushel, (av. 38 lbs.) 35-42 lbs.
StoracBfor
k>nston.
eu. ft.
40-43
43-48
80-07
90-6II
47-66
51^56
Through round holes, pundied in plates.
Chestnut through
Pea "
Buckwheat
Rice
Bariey " «
Culm •• A
FUBI*.
1355
Valoes of CoaU »ad Kow to ]l«n VliOHi.
(By jAy M. Whitluun.)
Gi^on boilers and chimney operating under natural draft and haying
nrtain sizes and dimensions, the capacities measured in steam output,
rlklcb can he produced therewith, when using good grades of these coals,
re as follows :
Semi-hituminous coal (8 to 10 per cent ash) . . .
Ko. 1 hnckwheat anthracite (18 to 22 per cent ash
in use) ^
TSo, 2 buckwheat anthracite, or rice (18 to 22 per
cent ash in use)
Percent.
100,
80
68
It ia more than likely that the percentage of ash and refuse obtained in
lerrice with Nos. 1 andr2 buckwheat will exceed the 18 to 22 per cent ahove
loted, while it is equally probable that with soft coal the percentage will
lot exceed from 8 to 10 per cent.
It Is, of course, a simple matter to increase the combustion of the small
lixee of anthracite by the use of a fan or a steam blast. A fan blast uses
Crom 2^ to 3 per cent of the steam product in the boilers, while the steam
blast, used for injecting air into a closed ash-pit, consumes from 7^ to 12
per cent of the steam produced by the boilers, and seldom operates under
IMS than 10 per cent. Hence, in making any estimates as to the relative
eosts of operating with these fuels, these deductions must be made if an
artificial draft must be used, in order to get net comparative results.
Qiren semi-bituminous and small-sizea anthracite coals of the ash com-
positions noted above, my experience has shown that the relation between
the eosts of operating the plant with these coals, under natural draft, to
prodaoe a given output, are :
8eml-bltuminons coal . .
Ko. 1 buckwheat coal . .
No. 2 buckwheat (rice) coal
Per Ton.
•1.33
1.00
.83
Paying these prices, the costs tor power under natural draft are the
same, no matter whicn coal is used, provided the cost of removing ashes
is ignored.
If the anthracite grades have to be burned with blasts, the relative prices
which one can afford to pay for producing a given quantity of steam are
as follows :
Draft.
Natural.
Fan Blast.
steam Blast.
Semi-bituminous ....
No. 1 bnokwheat
No. 2 buckwheat (rice) . . .
•1.33
• • •
• ■ •
...
• • •
•OJO
.76*
Semi-bituminous coals are burned to advantage only by exercising great
care in the handling of fires, and by the firemen exerting themselves
beyond what is necessary when burning buckwheat and rice anthracite
grades.
1356
STBAM.
Green wood eontaina from 30 to 60 per cent of
year In open air the moUture is 20 to 25 per eent.
The woods of yarioos trees are nearlv identical In chemical
which is practically as follows, showuig the composition of
wood, and of ordinary firewood holding nygroecopio moisture :
Desiccated Wood.
Garhon 60 per eent
Hydrogen 6 per cent
Oxygen 41 per cent
Nitrogen 1 per cent
Ash 2 per cent
100 per cent
Hygrometric water
moistiire. After ahook a
IOOjO
Some of the pines and others of the oonif eroos family contain hydroev'
hons (turpentine). Ash yaries in American woods from. .OS per eent to Ul
percent.
In steam boiler tests wood is assumed as 0.4 thevalae of tbe aanie weight of
coal.
The fuel yalue of the same weights of wood of all kinds Is praetieal|f Iks
; and it is important that the wood be dry.
^r«icM •r iR
F««d per CorA.
Weighs per
Gord, Lbs.
Equal in yalne to Coal,
in Lbs.
Ayeragepine
Poplar, chestnut, elm
Beech, red and black oak ....
White oak
2000
2360
3260
3850
4600
800 to S26
MO to 1060
130O tol4S0
1640 to 1715
Hickory and hard maple ....
1800 toaooo
A cord of wood = 4x4x8 = 128 cubic feet. About 60 per cent is toU
wood, and 44 per cent spaces.
Petroleum Is a hydrocarbon liquid which is found in abundanee In
ica and Europe. According to the analysis of M. Balnte^laire I>erille, tbs
composition of USpetroleums from different sources was found to be pnetf-
cally the same. Tne average specific gravity vras .870. The extreme and Om
average elementary compositions were as fbilows :
aicAl C«Hsp«attlOM of P««r»le«aa.
Carbon 82.0 to 87.1 per cent. Average, 84.7 per eeat.
Hydrogen 11.2 to 14.8 per cent. Average, 13.1 per cent.
Oxygen 0.5 to 5.7 percent. Average, 2.2 per eeat.
100.0
The total heating and evaporative powers of one pound of petioleuBi lu^
ing this average composition are as follows :
Total heating power = 145 [84.7 + (4.28 X 13.1)] = 20111 unlt».
Evaporative power : evaporating at 2129, water supplied at 82° = 18.29 Iba
Evaporative power : evaporating at 212P, water snppUed at 212<> = tLAS Iha
Petroleum oils are obtained in great variety by distiUatlofn frompeCTO'
leura. They are compounds of carbon and hydrogen, ranging fktxn C^ H^
to C„ H«4 ; or, in weight ;
1
FUEL.
1857
GlhmMical Coaip««itlo« of P«tr»le«
T-^^ (71.42 Carbon ) ^ ( 73.77 Carbon .
'^"* (28J>8 Hydrogen I ^ ( 26J23 Hydrogen
100.00
100.00
Mean.
. 72J»
, 27.40
IOOjOO
The speolfio grayity ranges from .688 to .792. The boiling point range*
from 80^ to 486^F. The total heating power rangee from 28067 to 20075 uiilts
of beat ; eqaivalent to the eraporation, at 212°jOf from 25.17 to 24.17 Ibe.
of wftter supplied at 029, or from 29X6 Ibe. to 37 Jr2 lbs. of water supplied
at212(>.
Wrmacos for the combustion of oil fuel need not be as large as when
Immins coal, as the latter, being solid matter, requires more nme for de-
oompoeition, and the elimination of the products and siqiporters of com-
bttstioii. Coal fuel requires a large Are chamber and the means for the
intrtxlaction of air beneath the grate-bars to aid combustion. Compared
with oil, the combustion of coal is tardy, and requires some aid by wav of
a strong draft. OU having no ash or refuse, when properly burned, requires
much less space for combustion, for the reason that, being a llquia, and the
compound of gases that are higniy inflammable when united in proper pro-
Sortloua, it gives off heat with the utmost rapidity, and at the point ot ignl-
on is all r^uly for consumption.
Prof. J. E. Denton has made a number of boiler evaporative tests, using
oil for fuel. In the following table the results of tests where various fuels
were used are brought together, and interesting comparisons are made be-
tween the cost of coal ana cost of oil. See " Power," Feb., 1902.
Cteaeoas Vaals.— Mr. Emerson McMillln (Am. Qtm. Lt. Asso., 1887)
made an exhaustive investigation of the subject of fuel gas ; he states that
the relatire values of these gases, considering that of natural gas as of unit
value, are:
Natural gas .
Coal gas . .
Water gas .
Prodneer gas
By Weight.
By Volume.
1000
949
292
76.6
1000
666
292
ISO
The water gas rated in the above table Is the gas obtained in the decom-
position of steam by incandescent carbon, and does not attempt to fix the
calorific ralue of ilfuminattng water gas, which may be carbureted so as to
exceed, when compared by volume, the value of coal gas.
Composition of Gases.
Hydrogen . . .
Marsh gas . .
Carbonic oxide
Oleflantgas . .
Carbonic acid .
Kitrogen . . .
Oxygen . . .
Water vapor
Sulphydno acid
Volume.
Natural
Goal
Water
Producer
Oas.
Oas.
Gas.
Gas.
2.18
46.00
45.00
6.00
93.60
40.00
2.00
3.00
OJSO
6.00
46.00
23.50
0.31
4.00
0.00
0.00
0.26
OJM
4.00
1.60
3.61
IJBO
2.00
66.00
0.34
OJSO
OJSO
0.00
0.00
liiO
1.60
1.00
0.20
• • •
• • •
• • •
100.00
100.00
100.00
100.00
Oreen vood
WMdaa I
1 30 lo S
ai«tur« la 30 to
BOporiBnIof *
-, . ^ lo a per MB* I
:h U priKtlcally m followe Oiovinf ths", 5
1, SQiTofonllniiry HrawoodWrliiigEyp 'j 1
^5 I
HTdroge
Hrtrometrlc water .
Some of the ptn« and oi
flper-, ' i '
bona (turpentine). AihTSrier.';
.i""-""'"'—
ood'
•
'f'
J'
1 ^ ?
*
i;?^""
"i
;5a
'/^l«
a-
-"^//l
1
2»
1
i
S
i»
pillp
Is
^ 1 1 » s 5 i
« 3 1 1 B I ! J
8 !; ^ S E: S I 'I
S ° ° ° ° ° - "l
|2 isll:^
g I ? 1 3 ! i
^ : s
I
/
WUBL. 1359
%
^•chmUcal •toldi
N^ be conveniently himdled by one man it is
"^ ^ beet hand firing:; but where good firemen
^V '< eonaiderable size, it is probable that
y ^"W ^^ stoker will result in economy, and
.*>
^y^^ ^0^ "^ pities of smokOi as the combustion
jV^^*^ ^^ ' ' tiie straight feed, as the Mnr-
^<** ^^8^ %K» ^^ ^ iinder-f eed of which the
*^ • . ^ ^ ^«X 'Chain stoker, by Ooxe and
lie two last-mentioned types,
stoker in the most scientific man-
anthracite region.
j8 of mechanfoal stokers are stated
I.E., vol. XTii. p. 668) to be as follows :
.16 burning of the cheapest grades of fuel.
. ants of 600or more h. p., when provided with
Economv in combustion, even under forced
.nent. 4. Constancy and uniformity of furnace
, clean at all times, and responding to sudden de-
. This should result in prolonged life of boilers.
%Mtdwuitagt», 1. High first cost, varying from f 26 to
^f grate area. 2. High cost of repairs per year, which.
,, is as much as $6 per square foot. 3. The dependence of
upon the stoker engine's working. 4. Steam cost of run-
« engine, which is from f tot of 1 per cent of the steam generated.
960 a year on a K^hour basis for 1000 h. p., where fuel is $2 per
v>Bt of steam used for a steam blast, or for driving a fan blast,
t either la used. This, for a steam blast, is firom 6 per cent to 11
■it of the steam senerated by the boilers, and from 3 oer cent to 6 per
ior a fan blast. This amounts to about $1000 per year for a steam blast,
vi 9600 a year in fuel for a fan blast, for a 1000 h. p. plant on a lO-hour
•^asis, when fuel is 92 per ton. 6. Skill required to operate the stoker.
Careless management causes either loss of fuel in the ash, or loss due to
poor combustion when the coal is too soon burned out on the grate, thus per-
mitting cold air to freely pass throush the ash. 7. The stoker is a machine
iubject to a severe service, and, lile any other machine, wears out and
requires constant attention.
W. W. Christie, in article in the Enffinterinig MagoM/^ne on the ** Economy
of Mechanical Stoking," says in part : The influence of the mechanical
stoker upon boiler efficiency has been discussed, but definite information
IS not readily obtained, although general opinions as to the advantage
of mechanical stoking are numerous.
The efficiency of a boiler, and consequently of a group of boilers, depends
UMn several independent and distinct factors.
JThus we have tne furnace efficlencv, a measure of the completeness of
the combustion in the furnace ; this is measured by the ratio of the tem-
Grature in the furnace to the temperature of the escaping gases. We
ve also the efficiency of the boiler proper, measured by the quantitv of
heat transmitted to the water eomparod with that generated in the fur-
nace.
There are also two other kinds of efficiencies— one the heat efficiency, per
POmid of fuel, the other the so-called " investment efficiency," which takes
mto account the cost of building, apparatus, boilers, chimneys, wages, and
isei.
It has been maintained that the most economical rate for steam-making
V that of ao evaporation of 4 lbs. of steam per hour per square foot of
heating surface, which some tests will show is the case. Other tests,
kowever, show that it may vary, while the steam economy referred to 1 lb.
of coal may remain constant.
The completeness of combustion can be told best by the temperature of
]^s escaping gases, and by an analysis of their chemical composition,
'^iiifl, for an excellent combustion, the temperature of discharge gases
uonU not be higher than 400-600<> F. If the percentage ef oxygen u 1.6
r
1348
8TBU(.
1
!
1 I
§
I
§
S
I
^ • • • • • p « ^« «
'U^a iEouuiiqo ^^\^
-dvAO Jioivii JO gpuao J ai
00 CO ■<»'«^o«««-« -1
*exa{)*nqinoo
|0 pvnoj 4»a oT pospu
;9i
I e* »^ ^**^»^w^
}o Ifdang i«9{)M09qx
«^9 eetuix Mjqx qiiM
|i I i§g§s§i§
-40J09IIX 0^9 oo|i^X ^Yliti
S8ii8
11
-jfy lo ifddng |«o|9U
IS S5
ESSSS)!
•JIY JO
X[ddfi8 ivoifojooqx ^%\I^
'9(q|9«nqmo3
JO panoj jo^ sponod^cri
ii
;9||f|||
12 3 |S?S|8SS8S
I
3
a
I
1
a
a
o
1,1
MP
2
1?
Sl5
m
I
o
a V
"^
BTTBL.
1349
Tmmipmkmtmw of Flr«.
By referenoe to the table of oombvutibles. it will be seen that the temper>
atvre of the lire is nearly the same for all kinds of combostibles, under sim-
ilar eonditions. If the temperature is known, the conditions of oombnstion
iM»y be inferred. The following table, from M. Pouillet, will enable the
temperature to be Judged by the appearance of the Are :
Appearance.
Temp. F.
Appearance.
Temp. P.
Bed, Imt Tlslble . .
" dull
** cherry, dull . .
" " full. .
•* " clear .
9770
1290
, 1470
16B0
1830
Orange, deep . . .
" clear . . .
White beat ....
" bright . . .
" daxzling . .
2010
2190
2370
2660
2790
Vo 4et«nata« Veaspcnstars by Wmaiom of IHetole, etc.
Sttbetance.
Tem.F.
MetaL
Tem.F.
Metal.
Tem.F.
Tallow . . .
Spermaceti .
wax, white .
Salphnr . .
Tin • . . .
9SP>
120
164
230
466
Bismuth .
I^ead. . .
Zinc . . .
Antimony .
Brass . .
618<'
630
793
810
1660
SiWer, pure . .
Gold, coin . .
Iron, cast, med.
Steel ....
Wrought iron .
1830»
2166
2010
2660
2910
lerlcas
Kind of Wood.
Hickory— Shell bark.
Wklteoak ....
Hickory — Bed heart
SonCbem pine . . .
BadoAk
Beech
Hard maple . . .
Virginia pine . . .
Spruce
New Jersey pine . .
Tellow pine • . *
White pine ....
Weight
per C^rd*
4460
8821
8706
8376
8264
3126
2878
2680
2326
2187
1904
1868
Value in Tons Ckial.
Anthracite
.606
JS2
JBOi
.460
.443
.426
JOl
.304
.316
.291
.260
.264
Bituminous
.481
.467
.426
.41
.394
.363
.293
.209
.24
.236
^
i
1362
BTEAIC
(Kopp: oometed by Porter.)
Gent.
Fabr.
Yolvme.
Cent.
Fahr.
Volume.
Gent.
Fkhr.
YolVM.
4«
89.2«
1.00000
aeo
86°
1.00686
7V>
1680
UBM
6
41
1.00001
40
104
1.00767
75
167
MM
10
BO
1XXXK»
46
113
ixne67
80
176
uan
16
60
1.00068
60
122
1.01186
86
186
UHD
90
68
1.00171
66
131
1.01423
90
194
25
77
1.00286
60
140
1.01678
96
908
UBM
ao
86
1.00425
66
148
14»1961
100
S12
iJNn
Water ft
(Hunt and Glapp, A. I. M. B., 1888.)
Water containing more than 6 parte per 100,000 of free snlpliiiric or aitik
aoid U liable to oanee serious oorroeion, not only of the metal of the boihr
itself, but of the pipes, oyllnders, pistons, and ralres with which the
eomes in contact.
The total resldae in water osed for making steam eaneee the interior J
iiigs of boilers to become ooated, and often prodaees a dangerous hard sbbIb,
which prcTeuts the cooling action of the water from proteotiiig the bcw
of earboiie
against baming.
liime and magnesia bicarbonates In water lose their ex<
acid on boiling, and often, especially when the water eontalaa snlnksrie
aoid, produce, with the other solid residaes constantly being fmmed sj &•
eraporatlon, a Tory hard and insoluble scale. A larger "^
parts per 100,000 of total solid resldve will ordinari^ o
scale, and should condemn the water for use in steam boilers,
ter supply can be obtained.
The xoUowing is a tabulated form of the eauses of trouble with wstsr for
steam purposes, and the proposed remedies, giren by Pn^. I4. M. Mortsa-
OAUSB8 OF nrCBUSTATIOH.
1. Deposition of suspended matter.
2. Deposition of deposed salts from concentration.
8. Deposition of carbonates of lime and magnesia by boiling off carbsh
Aisid{Which holds them in solution.
4. Deposition of sulphates of lime, because sulphate of Ame is bntsKf^Uf
soluble in cold water, less soluble in not water, insoluble above 23tP F.
6 Deposition of magnesia, because magnesium salts decompose at U^
temperature.
6. Deposition of lime soap, Iron soap, etc., formed by sa|M>nHiratiBS «
grease.
MXAJfS rOB rBBTZHmrO ZKOBVBTATIOK.
1. Filtration.
2. Blowing off.
3. Use of internal collecting apparatus or dericee for directing the di*
lation.
4. Heating feed-water. _
• See also '* Boiler Waters ; Scale, Corrosion, Foaming ** by W. WsDim
CbriBtie.
WATEB.
1363
6. Ohemical or oUior treatment of water in boiler.
6. Introdnetion of sine into boiler.
7. Chemieal treatment of water ontaide of boiler.
TABUULB TIXW.
TVoubUaotne Substance,
Sediment, mnd, clay, etc.
BfOAdily soluble salts.
Bicarbonates of lime, magnesia, )
iron. j
Sulphate of lime.
Trtmble.
Incrustation.
M
f«
(I
Chloride and sulphate of n\agne- ) Corrosion.
Mnm. )
Carbonate of soda in large) ^^^i^^
amounts. 1 ^
Acid (in mine waters). Corrosion.
Diasolved carbonic acid and ozy- )
gem }
Oreaae (from condensed water).
Organic matter (sewage).
Organic matter.
««
ct
Priming.
(Corrosion.
Remedy or Palliation,
Filtration, Blowing off.
Blowing off.
f Heating feed. Addition of
-l caustic soda, lime, or
(^ magnesia, etc.
(Addition of earb. toda,
( barium chloride, etc.
(Addition of carbonate of
( soda, etc.
(Addition of barium chlo-
\ ride, etc.
AlkaU.
fHeating feed. Addition
•< of caustic soda, slacked
i^ lime, etc.
{Slacked lime and filtering,
Carbonate of soda.
Substitute mineral oil.
(Precipitate with alum or
\ f erne chloride and filter-
Ditto.
AolwbllltiM of Acale-aiAklMr Matortela.
(" Boiler Incrustation,** F. J. Bowan.)
The salts of Ume and magnesia are the most common of the impurities
found in water. Carbonate of lime is held in solution in fresh water by an
excess of carbonic acid. By heating the water the excess of carbonic acid
is driven off and the greater part of the carbonate precipitated. At ordi-
narr temoeraturee carbonate of lime is soluble in from 16,000 to 24,000 times
its volume of water ; at 212o P. it is but slightly soluble, and at 290» P. (43
Iba. pressure) it is insoluble. - . . ^ .^ *
The solubility of sulphate of lime is also affected by the temperature ;
according to Begnault, its greatest solubility is at OS® P., where it dissolves
in 393 times Its weight of water ; at 212^ P. it Is only soluble in4fl0 times its
weight of water, and according to M. Ck>ut4, it is insoluble at 290°P.
Carbonate of magnesia usniOly exists in much smaller quantitv than the
salts of lime. The effect of temperature on its solubility is similar to that
of carbonate of lime. , . «^ « ., „ am *..*^
Prof. B. H. Thurston, in his " Manual of Steam Boilers," p. 281, states
that:
The temperatures at which calcareous matters are precipitated are :
Carbonate of lime between 170° and 248° P.
Sulphate of lime between 284° and 424® P.
Chloride of magnesium between 2120and 267o F.
Chloride of sodium between 824<> and 9eiP F.
1364 STEAM.
<* IirosuBTATioir AND 8Xi>nnEST/' Prof.ThantonMys, " aredepotfteAla
boilers, the one by the preoipitatlon of mineral or other salts pr
held In eolation in the feed-water, the other by the deposition of
insolable matters, usually earths, carried into it in snspensioii or
chanical admixture. Occasionally also T^etable matter of a gjtutij
nature is held in solution in the feed-water, and, precipitated by heatv
concentration, covers the heating-surfaces with a coating almost impuma^
ble to heat, and hence liable to cause an over-heating that may be ▼ery Ab-
gerous to the structure. A powdery mineral deposit sometimes me* wttli
equidly dangerous, and for tne same reason. The animal and TCigetaMssBi
and nreases carried over from the condenser or feed-water beater arsste
rery likely to cause trouble. Only mineral oils should be permitted j
thus introduced, and that in minimum quantity. Both the eiT
the safety of the boiler are endangered by any of these deposits.
"The only posltlTe and certain remedy for incmstatloii
once deposited la periodical removal by mechanical means, at si
frequent intervtUs to Insure scalnst infury by too great aeenmnlation. Be-
tween times, some good may be done by special expedients suited to As
individual case. No one process and no one antidote will suifioe for sB
cases.
" Where carbonate of lime exists, sal-ammoniac mar be used as a pn-
ventlve of Incrustation, a double decomposition oocurrmg, resultxnff in the
production of ammonium carbonate and calcium chloride — bothocwhiefc
are soluble, and the first of which is volatile. The bicarbonate msT be lb
part precipitated before use by heating to the boiling-point, and thus orssk-
ing up the salt and precipitating the insoluble carbonate. Solntioos of
caustic lime and metallic sine act In the same manner. Waters enrntaistpg
tannic acid and the acid Juices of oak, sumach, logrwood, hemloek, and odMr
woods, are sometimes employed, but are apt to Injure the iron of the boiisr,
as may acetic or other acla contained in the various saedbarine mattsa
of tot introduced into the boiler to prevent scale, and which also make the
lime-sulphate scale more troublesome than when dean. Oiganie maSteai
should never be used.
<• The sulphate scale is sometimes attacked by the carbonate of soda, the
products being a soluble sodium sulphate and a pulTeruIent insolnble esl>
cium carbonate, which settles to the bottom like other sediments and b
easily washed off the heatinMurface^. Barium chloride acts slalbzfy.
producing barium sulphate and calcium chloride. All the alkalies are mm
at times to reduce incrustations of calcium sulphate, as is pure erode petrD>
leum, the tannat^ of soda, and^other ohemioals.
" The effect of incrustation and of d^ioslts of various kinds Is to eBor-
mously reduce the conducting power of heatlng-surfaees ; so mn^ so, that
the power, as well as the economic efficiency of a boiler, may beeome very
greatly reduced below that for which it Is rated, and the supply of stesra
f umisned by it may become wholly inadequate to the requiiements at Um
case.
'* It is estimated that a sixteenth of an inch thickness of hard ■ scale* ob
the heating-surface of a boiler will cause a waste of nearly one-eigbth ite
efflclency, and the waste increases as the sqiiare of its thickness. Th» boil-
ers of steam vessels are peculiarly liable to Injury ft'om this cause whert
using salt water, and the introduction of tiie surface-eondensex' has bees
thus Drought about as a remedy. lAnd boilers are subject to incrustatios
by the carbonate and other salts of lime, and by the deposit of sand or aittt
mechanically suspended in the feed-water.**
Kerosene oil ('^Boiler Incrustation,'* Bowan>hss been used to advantage ti
removing and preventing incrustation. From extended eiqierinieiits made
on a 100 h. p. water tube boiler, fed with water containing eJ5 grains d
soUd matter per gallon, it was found that one quart kerosene oil per dsy
was sufficient to keep the boiler entirely free from scale. Prior to the la-
troductlon of the kerosene oil, the water had a corrosive action upon wtrnt
of the fittings attached to the boiler ; but after the oil had been lued for a
few months it was found that the corrosive action had ceased.
It should be stated, however, that obiection has been made to tbe Infeiv
duction of kerosene oil into a boiler for the purpose of preventing
WATER. 1365
tion, on acoonnt of the poMibillty of soine of the oil passing with the steam
into the cylinder of the engine, and neutralizing the eifeot of the lubricant
in the cylinder.
When oil is used to remove scale from steam-boilers, too much care can-
not be exercised to make sure that it is free from srease or animal oil.
Kothing but pure mineral oil should be used. Gruoe petroleum is one
thing : black oil, which may mean almost anything, is Tery likely to be
sometning quite difTereut.
The action of grease in a boiler is peculiar. It does not dissolve in the
water, nor does it decompose, neither does it remain on top of the water ;
but it seems to form itself into ** slugs," which at first seem to be slightly
lighter than the water, so that the circulation of the water carries them
about at will. After a short season of boiling, these ** slugs," or suspended
drops, acquire a certain degree of ** stickiness," so that when they come in
contact with shell and flues of the boiler, they begin to adhere thereto.
Then under the action of heat they begin the prooess of *' Tarnishing" the
interior of the boiler. The thinnest possible coating of this varnish is suf-
ficient to bring about over-heating of the plates.
The time when damage is most ukelv to occur is after the fires are banked,
for then, the formation of steam being checked, the circulation of water
stoM, and the grease thus has an opportunity to settle on the bottom of the
boiler and prevent contact of the water with the fircHBheets. Under these
circumstances, a very low dwree of heat in the furnace is sufficient to over-
heat the plates to such an extent that bulsing is sure to occur.
JSinc OS a Scale Preventive. — Dr. CorBigny gives the following hypoth-
esis : he says that " the two metals, iron and nnc. surrounded by water at a
high temperature, form a voltaic pile with a single liquid, wni<^ slowly
decomposes the water. The liberated oxygen combines with the most oxy-
disable metal, the sine, and its hydrogen equivalent is disengaged at the
surface of the iron. Tnere is thus generated over the whole extent of the
iron influenced a very feeble but continuous current of hydrogen^ and
the bubbles of this gas Isolate at each instant the metsJllc surface nom the
8cale*fonning substance. If .there is but little of the latter, it is penetrated
by these bubbles and reduced to mud ; if there is more, coherent scale is
produced, which, beins kept off by the intervening stratum of hydrogen,
takes the form of the Iron surface without adhering to it."
Zinc, in the shape of blocks, slabs, or as shavings inclosed in a perforated
vessel, should be suspended througnout the water space of a boiler, care
being used in setting perfect metallic contact between the sine and the
boiler. It should not oe suspended directly over the furnace, as the oxide
might faU upon the surface and be the cause of the plate being over*heated.
The quantity placed in a boiler should vary with the hardness of the water,
and the amount used, and should be measured by the surface preseMted.
Generally one square inch of surface for erery 60 lbs. water in the boiler is
sidficient. The British Admiralty recommends the renewing of the blocks
whenever the decay of the sine has penetrated the slab to a depth of \ inch
below the surface.
PariflcatloM of F««d*W^»ter b^ BofliBgr.
Sulphates can be largely removed from feed-water by heating it to the tem-
perature due to bollMT pressure in a feedrwater heater, or " live steam puri-
fier " before introduction to boiler. This precinitates those salts In the heater
and the water can then if necessary be pumpea through a filter into the boiler.
The feed-water is first heated as hot as possible in the ordinary exhaust
feed-water heater in which the carbonates are precipitated, and then run
through the purifier, which is most generally a receptacle containing a
number of shallow pans, that can be removed for cleaning, over which the
feed- water is allowed to flow from one to the other In a thbi sheet. Live
steam at boiler-pressure is introduced into the purifier, heating the water
to a temperature high enough to precipitate the salts which form scale on
the pans. This method of treating feea-water Is said to largely increase the
efl&deucy of a boiler plant by the almost complete avoidance of scale.
Purification of feed-water by filtration before introduction to the system is
often practised with good results.
Wlura From.
BnRUo. N. y.,I«ke Erla . . .
PltUbnrgb,Alleih«iiTRlTer . .
PItttbursb, UctooneuolAKiTer .
PIttiburKh, Pib,«nealBnlreU. .
HIlwankM, WlieoiulnKlver . .
Gklviatan, Teiu, 1
GklTMton, T«IM, 3
Ootmnbiu, Ohio
WuhtDgMn. D. C. oltT iiinilT .
Bkltimon, Hd., oItT topplT . .
SlonCltf, I».,eitTiiimil* . . .
LmAdoUi,!^.,!
BBTOttT.HloUgu. Hirer .
ClnolDitMl, Ohki RlTvr . .
lulppi BlTsr, ftbOTS HbKi
Croton BlTM. ■
N. T. ...
CrotoD BItbt 1
I Croton Dun,
f
1
i
i
1
1
3
t
1
6.W
o.«
0.-8
t.M
IStt
WAt
IM
0.60
IM
i.n
.11
10.W
.16
.40
IM
,»
M
IJO
III
PUMPS. 1367
These sboiild be at leaat double the oepaolty found by eelenUtioa from
the amoiint of water required for the engines, to allow for blowing oif, leak-
age. Blip in the pumpe themeelTee, etc., and to enable the pump to keep
down steam in ease of sudden stoppage of the engines when the fires hap-
pen to be brisk, and in fact should be large enough to supply the boilers
when run at their full capaoity. In addition, for all important plants, there
should be either a duplioate feed-pump or an injector to act as stand-by in
case of accident. The speed of the plunger or piston may be 60 feet per
minute and should never exceed 100 feet per minute, else undue wear and
tear of the Talves results, and the efficiency is reduced. If the pump be re-
quired to stand idle without continually working, the plunger or piston and
rod should be of brass.
If
D = diameter of barrel in inches,
8 = stroke in inches,
n =: number of useful strokes per minute,
w = cubic feet of water pumped per hour,
W =: lbs. of water pumped per hour ;
wz=lJ IJ^Sh.
If Sn = 60,
and
1.36
Bubber tuItcs may be used for cold water, but brass, rubber composition,
or other suitable material is required for hot water or oil.
If a new pump will not start, ft may be due to its imperfect connections or
temporary stlifness ofpump.
Unless thesuetion lift and length of snpplr pipe be moderate, afoot-TalTC,
a charging connectton, and a racuum chamber are desirable. The suction-
nipe must be entirely free from air leakage. If the pump refuses to start
lifting water with full pressure on, on account of the air in the pump-cham-
ber not being dislodged, but only compressed each stroke, arrange for run-
ning without pressure imtU the air is expelled and water flows. This is
done with a oheck-Talre in the delivery-pipe, and a waste dellTery which
may be closed when water flows.
«**^ — *Tw — A*?**,^'^**^^^r:^**'^ • '"'•• »uction-plpe, any good pump
fltted with metal TalTesMdwJtthot-water packing will pump water har-
In^a temperature of JU2o, or higher. If so pficedthat the water will flow
«.S?5*'t ^- yianey.*" " Power," gives the following formula for doter-
g^g|^*o what height water of temperatures below Ac boiling point can
D = lift in feet,
« . ^= absolute pressure on surfkee of water ; if open to air =z 14.7 Iba
Band IT r= constants. Seetoble.
1368
STBAX.
Water Temp.
B.
•
W.
Water Temp.
B.
W
Degrees F.
Degrees F.
40
0.122
62.42
130
2.216
ita
60
0.178
62.41
140
2.879
OM
00
0.254
62.37
UO
3.708
ajD
70
0.360
62.31
160
4.731
«ijh
80
OJS03
62.22
170
6J86
ttJi
90
0.003
62.12
180
IJSll
Bm
100
0.942
62.00
190
9J36
AS
110
1.267
61.87
200
1L526
ttJS
120
1.686
61.72
210
14.127
Gin
Spe«4 of ITater throvfh
TalT«b
The speed of water flowing tbrough plDes and passages in pumps Tiris
from 100 to 200 feet per minute. Tlie loss from friction will be ooottdflnM
if the higher speed is exceeded.
The area of Talves shoald be sui&cient to permit the water to piM al t
speed not exceeding 260 feet per minute.
The amount of steam which an average engine will reqaire per iadiesiei
horse-power is usually taken at 30 pounds. It Taries widely, however, tm
about 12 pounds in the best class ox triple expansion condensing ^yP**^
to considerably oyer 90 pounds in many direcUacting pumps. WMn tt
engine is oyerloaded or underloaded more water per horsepower wHl ken-
quired than when operated at rated capacity. HorisontsI tabular bQai0
will evaporate on an average from 2 to 3 pounds of water per equare Is*
heating-surface per hour, but may be forced up to 6 pounds if the grttoiM^
face is too large or the draught too great for eoononucal working.
Mb«s of I^lrect-actti
The two following tables are selected as representing the two
types of dlrect-actlj^ pump, vis., the slngle-cylmder and the duplex.
MM^^mej of •■saII lMrec«-«ctlar Pvaips.
In " Reports of Judges of Philadelphia Exhibition," 1876, Qnm Ot
Ghas. £. Smery says : ** Experiments made with steam-pumps st ^^^J^^
lean Institute ExUbition of 1867 showed that average sise 8tea]n-j)iDiiis »
not, on the average, utilise more than 60 per cent of the Indieateapovw*
the steam oylinders, the remainder being abeorbed in the friction of tlte*
ffine. but more particularly in the passage of the water throngb the pn^
Again, all ordinary steam-pumps for miscellaneous use, require ^Jj^
steam-cylinder shall have three to four times the »ek of the wate^eplM[
to give suflloient power when the steam is aoddentally low ; heiiee,«igg
pumps usually work axralnst the atmospheric pressure, the net or ^f^
pressure forms a small percentage of the total pressure, wbit'h, ^**
large extent of radiating stO^leuse exposed and the total absence of expjMM
makes the expenditure of steam very large. One pnmp tested Te^u'^f^
pounds weight of steam per indicated horse-power per hour, and it ii*^
lleved that the cost will rarely fall below 60 pounds ; and as onlf 9F*
cent of the indicated power is utilized. It may be safely stated that oritoST
steam pumps rarely require lees than 120 pounds of stesm perhov^*j!
horse-power utilized in raising water, equivalent to a dutv of onlr 15.WJ5
foot pounds per 100 pounds of coal. With larger steam-pumps, pardfa^
when they are proportioned for the work to be done, the duty will be a*""
rially increased.
I tor onlliiU7 Mrrles
1
i
1
cp«itr
i
1
"~"'
•3
J
^
H^..
J
3
■s
1
1
i
1
J
s
i s
£
t
1
.a
s
3
if
1
i
1
1
H
1
j
4
3i
5
.14
100
130 18
ffi
tl
t
J.
5
.27
am
130 SS
{
7
MO
1
IB
1
278
138 M
Bi
.73
378
7
10
1.M
xo
110 180
88
17
1
8*
e
10
ISO
zo
380
110 330
eg
88
17
il
4
12
iiou
aw
100 100
87
!»)
100 281
88
jo'
B
380
100 408
88
30}
8
100 281
1
t
i
12
4.08
xo
100 408
SO
[
8.OT
see
100 897
80
I
4jia
280
too 408
0.13
300
TO 428
est
80
i
12
12
380
100 zm
6»
284
13
16
8.8C
88
^
14
KB
70 8W
88
W{
0
4.U
09
BO*
16
e-u
70 438
S3
!8
a.iB
150
BO 408
38
13
SCO
108 Bs;
8B
88
13
8.80
88
m
S
13
24
IBO
80 887
»
14
94
ISM
180
84
IS
80 1114
84
34
IS
24
GO lOM
38
14
12.00
1TB
70 840
18
ST
14
M
is.se
180
loe
84
9
W
i3.a!
1TB
80 II 14
88
34
180
80 10M
2
10
M
28.43
1»
40
4
13
»*
30.88
1S8
80 lOM
38
12
a
135
BO 1833
«
4
M
12B
BO ISK
40
8
34
se!4s
118
80 tSKi
40
4
13
»
31
n.M
13B
BO 103
40
13
WJW
1»
SO 1875
lao
40
3
18
"
(BMsdard iliM tor oi
1
1
e
If!
if!
1
i
1
\
10
10
s
1
1
1
n
la
K
s
f
1
1
4
IB
!:
i
10
10
i
10
M
.10
.10
1
I.2I
i.es
ii
2.«
SJIT
s
4^
4.80
s!fle
MO
100" 300
lOo" uo
lis:gi
76 |- IH
TS " lae
76" 13B
75" las
TS" US
TB" las
TB" iX
TS " 1»
;b '■ UB
s::s
TB" 1»
7B " lae
i::g
CO" IQO
JO" 100
70" lOQ
zls
13B" UC
180" apt
aiB|; «
MB" 41
S«" SH
SB" Gl
sas" 81
MB" n
s«" ei
E30" HI
UO" OK
BIO" 01
TOO "12
!S::i!
TOO "141
\i
W= water lii}M>ted la ponwli h>r boor.
P = sUiun pramm In pounds per iqiiBn
T~ dlBiMl«r of tbnot la mllllBaten.
INJXCT0B8.
1871
ir= 1280 i)«Vp
= 1.98<f«V?
Xbe rale gtven by Raaklne, ** Steam Engine/' p. 477, for finding the proper
Mstioiial area in square inohes for the narroweet part of the nossle U as
>llowB :
oabio feet per hour groei feed-water
area =: . ■ — —
800 Vpreeiure in atmospheres
Xhe ezpendltnre of steam is abont one-fourteenth the rolnme of water
■Jeoted.
^The following table gires the water delirered for dllferent siaes of injeo-
[>rB at different pressures ; but when the injeotor has to lift its water a do*
neilon must be made yarying ftom 10 to 30 per cent aocording to the lift.
Itollverlee for MSw (MesHS I^Jectora.
s .
Is
2
8
4
5
6
7
8
9
10
11
12
IS
14
15
16
17
18
19
Pressure of Steam.
30 lbs.
60 lbs.
80 lbs.
100 lbs.
120 lbs.
140 lbs.
Delivery in Gallons per Hour.
48
97
178
272
382
683
1068
1317
1567
1840
2188
2100
2787
8146
3637
4366
61
71
80
87
188
160
178
196
246
286
817
848
886
445
486
546
666
640
715
783
765
871
973
1067
965
1137
1272
1308
1247
1440
1610
1763
1640
1777
1987
2177
1863
2160
2405
2638
2217
2660
2861
8136
2602
3006
3358
3680
8018
8485
8886
4267
8466
4000
4471
4900
3942
4651
6087
6676
4460
6138
5743
6291
4890
5760
6438
7065
6660
6418
7176
7861
6160
7110
7900
8710
93
211
876
687
846
1162
1606
1905
2369
2846
3887
3976
4610
5292
6022
6796
7633
8492
9410
1
I
IK
nr
t
2
2
2
2
2
2
2
2
2
3
1 millimeter = ^ inch, nearly.
As the rertloal distance the injeotor lifts is increased, a greater steam
pressure is required to start the injector, and the highest steam pressure at
Which it will work is gradually decreased.
If the feed-water is heated a greater steam pressure is required to start
the injector, and it will not work with as high steam pressure.
The capacity of an injeotor is decreased as the lift is increased or the feed-
water heated.
JP^rfor^ABC* of 1^1 •€<•■«. — W. Sellers & Go. state that one of
fhdr injectors delivered 25.5 lbs. water to a boiler per pound of steam ;
tteam pressure 65 lbs.: temperature of feed, 04<' F.
Schaelfer ft Budenberg state that their injectors will deliver 1 gallon
water to a boiler for from 0.4 to 0.8 lbs. steam. They also state that the
temperatures of feed-water taken by their injector, if non-lifting or at a
kw lift, can be as follows :
1372
STEAM.
PreBSure, lbs. . aS to 46, 60 to 86, 90,106, 120, US, —
Temperature, ^F., 144 to 136, 133 to 130, 120, 122, 118 to 113, 1€0 to UB, IN to
The Uayden & Derby Mfg. Co. state that the results giren belov ars
aetual tests of Metropolitan Double-Tube injectors.
'VrttM Cold I*««4-irater.
I Starts with 14 lbs. steam pressure.
( Works up to 260 lbs. steam praaaure*
I Starts with 23 lbs. steam presanre.
\ Works up to 220 lbs. steam prearare.
( Starts with 27 lbs. steam preasnre.
\ Works up to 175 lbs. steam pressure.
( Starts with 42 lbs. steam pressure.
I Works up to 136 lbs. steam pressure.
i Starts with 14 lbs. steam prssaiire.
( Works up to 260 lbs. steam preasore.
i Starts with 16 lbs. steam pressure.
( Works up to 210 lbs. steam prewura.
( Starts with 26 lbs. steam pressure.
( Works up to 160 lbs. steam pressure^
( Starts with 37 lbs. steam pressure.
( IVorks up to 120 lbs. steam pressure.
1 Starts with 46 lbs. steam pressure.
( Works up to 70 lbs. steam pressure.
( Starts with 16 lbs. steam pressure.
I Works up to 210 lbs. steam pressure.
j Starts with 20 lbs. steam pressure.
( Works up to 186 lbs. steam pressure.
( Starts with 30 lbs. steam pressure.
( Works up to 120 lbs. steam pressure.
I Starts with 42 lbs. steam pressure.
[ Works up to 76 lbs. steam pressure.
( Starts with 20 lbs. steam premure.
t Works up to 186 lbs. steam pi
On a 2-foot lift :
On an 6-foot lift :
On a 14-foot lift :
On a 20-foot lift :
When not lifting :
"Wink
Ona»-footUft:
On an 8-foot lift :
On a 14-foot lift :
On a 20-foot lift :
When not lifting :
On a 2-foot lift:
On an 6-foot lift :
On a 14-foot lift :
When not lifting :
Witb F««»*-Wat«r at 1*0° W.
On a short lift, or when not lifting, ^^^f^L^l^^^J^^^r-^
pressures from 20 lbs. to 120 lbs., and on an Moot lift with steem preavM
from 86 lbs. to 70 lbs. . ^ _^ . ^, ._. ^««s-. ■<
ExHaaMt IiMt'Ctovs working with exhaust steam trma »" engMM"
about atmospheric pressure will Bcllver water ««»*»?* ^?*42r»f5?S^«
exceedinir 80 lbs. per square inch. The temperature <rfJS^J?S wf "*^ *
high as 190° F., while 12 per cent of the water delivered wiu neeaaOfm
steam. For pressures orer 80 lbs. it is neeessary to supplement theezia»
steam with a Jet of lire steam.
W^J«ct«r Ts. Pvmp fer Fesidlar S«ll«»v«*
The relative value of injectors, direct-acting steam pumps, and p«JJ
driven from the engine, Is a question of Importance to aU steam-usen. iw
following UbleC* Stevens Indicator," 1888) has been calculated by R*
Jacobs, M. B., from data obtained by experim^t. It will be notk«d»K
when feeding cold water direct to boilers, the injector has a alight ee«<^Ti
but when feeding through a heater a pump is much the moat economnl*
INJSOTOBS.
1S78
Xetiliod of Supplying Feed-Watef
k>B< '
toiler.
Temperature of Feed-Water as
deBTered to the Pump or to the
Injector, 00° F. BateofErap-
oration of Boiler, 10 lbs. of
Water per pound of Coal from
and at 212o F.
Mrect-actinff pomp feeding water
at 00°, witnont a heater ....
Qjeetor feeding water at 160°,
witbont a heater
Djeotor feeding through a heater
in wMch the water ie heated
troml50° to200°
Nrect-actlng pump feeding water
tliroiigh a heater, In whieh it is
heated from 9P to 2009 ....
iearedpnmp, run from the engine,
feeding water through a heater,
in vbieh it la heated from eSP to
aOQo
Belatlre Amount
of Coal Required
per Unit of Time,
the Amount for a
Direct-Acting
Pump, Feeding
Water at 60^ with
out a Heater,beiiig
taken as Unity.
Saving of Fuel
oyer the
Amount
Bequired
when the
Boiler is Fed by
a Direct-
Acting Pump
without Heater.
.0
1.6 per cent.
6.2 "
12.1 "
18.2
«<
Msea for Vecd-WAter .PIpoe.
Three and six-tenths gallons of feed-water are required for each h. p. per
lour. This makes 6 gaUonsper minute for a 100 h. p. boiler. In proportion-
ng pipes, howcTer, it Is well to remember that boiler-work is seldom per-
lisetly stcAdy, and that as the engine cuts off Just as much steam as the work
iMnands at each stroke, all the diwcrepaneies of demtmd and avpply have to
k eqwUiaed in the boiler. Therefore we may often hare to evaporate dur-
ing one-half hour 60 to 76 per cent more than the normal requirements. For
mu reason it Is sound policy to arrange the feed-pipes so that 10 gallons
ptr minute may flow through them, without undue speed or friction, for
Bach 100 h. p. of boiler capacity. The following tables will facilitate tilis
CMTi»r liAte of Flow of Water, la Coet poi
Xliroagrli Ptp«e of Varione Siaoe, for 'Varjlogr
^^oaantitlea of JTlow.
Gallons i
perMln. ^
[in
lin.
Uin.
14 in.
2 in.
24 in.
3 m.
4 in.
6
218
122^
784
644
304
194
134
1
10
43fl
246
167
109
61
38
27
154
16
663
867^
2354
1634
914
564
404
23
20
87S
400
314
218
122
78
64
n
26 :
100€
6124
3924
2724
1624
974
674
90
736
451
327
183
117
81
46
36
8574
6494
3814
2134
1364
944
n
40
900
628
436
244
156
106
46
11024
7064
4904
2744
1754
1214
69
60
785
545
306
196
135
76S
76
11774
8174
4674
2924
2024
116
100
1090
610
380
270
1634
126
• • •
7624
4874
3374
191}
160
• • •
915
685
406
230
176
200
• • • •
• • ■
• • •
10674
1220
6824
780
4724
540
2684
30^
V
1374
8TSAM.
VAlile CMt«i
riqma
re iBcli, f«r Pipe lOO JPeeC
(ByG.A.lSUis,
C.E.)
Gallon*
oharged ^
perMin.
Mn.
lin.
Uin.
l|in.
2 in.
21 in.
Sin.
4K
5
3J
0.84
0.31
0.12
• ■ •
• « •
• • ■
• * •
10 1
13.0
3.16
1.06
0.47
0.12
■ • ■
• • •
. . •
15 1
».7
6.96
2^
Oi»7
...
• • •
• • fl
• • .
20 (
{0.4
12.3
4.07
1.66
0.42
• • •
• « •
. « ■
95
r8.o
10.0
&40
2.62
• • •
0^1
0.10
• • •
SO
■ •
27.5
9.16
3.75
OJl
• • «
» « •
. . «
a5
» • •
37.0
12.4
5.06
• • •
■ • •
• « •
. . •
40
• •
48.0
16.1
6J92
1.60
• ■ •
• • •
« • •
45
» • •
• • •
20.2
8.15
* • «
• » •
■ » «
...
60
> • •
24.9
10.0
2.44
0.81
oias
Oj09
76
1 • •
56.1
22.4
6.32
1.80
0.74
• • «
100
» • •
39.0
9.46
3.20
1.S1
OlB
125
1 • •
■ • •
14.9
AM
1.90
• • a
150
» • •
• • •
21.2
lA
SL8S
%M
175
• •
• • •
28.1
9.46
3.85
• • •
200
■
• ■ •
37 JS
12.47
5jQ3
IJl
•f Head due te
B«ndB prodcoe a loss of head in the flow of water in pipes.
giTes the following formula for this loes :
J/=/ ^ where ir= loMof head in feet,/=eo«ffieieiitof fileCloe,9=io»
looitj of flow in feet per second, g = 32.2.
As the loss of head or pressure is in most cases more rnTiTrmtnntli itamtl
pounds per square inch, we may change this formula by mnld^yiaily
0.493, which is the equivalent in pounds per square inch for one foot mm.
ItP= loss in pressure in pounds per square inch, J^^ coefficifent of M»>
tlon.
Pzz F 2T-1I V being the same as before.
From this formula has been calculated the following table of Talnss for J(
eorresponding to rarions exterior angles. A,
A —
20»
0J020
40<'
0.060
45<'
0.079
60°
0.158
800
0.320
90O
0.426
100»
04M6
lioo
0.074
1209
This applies to such short bttids as are found in ordinary flttinn, saeltf
90° and 4BP EUs, Tees, ete.
A globe Talre will produce a loss about equal to two 90^ bends, a stnMi^
way Talve about equal to one 46^ bend. To use the abore formula jtscW
tp&ed p. iecond, bewg one^xtietk of tkatftmnd in TYMep. 1373 ; s^eaniHl
tpeedi and divide the retult by 64.4; mnUtivly the quotient by the fsMtf
value ofF eorreeponding to the angle qf the mrn, A.
For Instance, a 400 h.p. battery of hollers is to be fed throagh » 94Bdk ffe^
Allowing for fluctuations we figure 40 gallons per minute, w***ifig 2inwl
per minute speed, equal to a refoeity of 4.6 per second. Suppose our p^li
In all 75 feet long; we have from luble No. 36, for 40 gaUons penaMHb
1.60 pounds loss ; for 75 feet we hare only 75 per cent of this = L20 psarfa
Suppose we hare 6 right-angled ells, each giving Fz=: 0.426. We havt Ass
4.06 X 4X)6 = 16.48 ;diTide this by 644 = 0,256. Multiply this by jr-USS
FBBD WATBR HEATERS. 1375
pounds, and as there are 6 ells, multiply again by 0, and m hare 6 x 0.4aB x
CL2S6 = 0.654. The total friction in the pipe is therefore 1.90 + OUIM = 1.8M
pounds per square inch. If the boiler pressure is 100 pounds and the water
ferel in the boiler is 8 feet higher than the pump suction level, we have first
8 X 0.438 = 3.404 pounds. The total pressure on the pump plunger then is
100+3.464 4- li64= 106.32 pounds per square inch, if in place of 6 right-
angled ells we had used three 45^ ells, they would have cost us only 3 X
O.0TO = 0.287 pounds: 0.237 X 0.266 = 0.061. ^ ^^ ^ .^ ^ . ,
The toUl friction head would haye been 1.20 4- 0.061 = 1.261, and the total
pressure on the plunger 100 + 3.464 4- 1.261 = 104.73 pounds per square inch,
a saving over the other plan of nearly 0.6 pounds.
To be aoourate, we ought to add a certain head in either case, ** to produoe
the Telocity." But thisis very small, being for velocities of :
2; 3; 4; 5; 6: 8; 10; 12 and 18 feet per see.
0.027 ; 0.061 ; 0.108 ; 0.168 ; 0.244 ; 0.438 ; 0.672 ; 0.970 and 2.18 lbs. per sq. in.
Our results should therefore haye been increased by about 0.11 pounds.
It is usual, however, to use larger pipes, and thus to materially reduce the
friotional losses.
(W. W. Christie.)
Feed Water Heaters may be classified in this way :
( Steam tube.
Closed Heaters (indirect) i Water tube.
rx_ « ^ ,M *x (Atmospheric.
Open Heaters (dlreot) \ Vacuum.
The open heater is usually made of cast iron, as this material will with-
stand the corrosive action of acids found in feed-waters better than any
other metal. In this type of heater the exhaust steam from engines and
pumps, and the feed-water broken up into drops by suitable means, are
brought into immediate contact, and the steam not condensed in heating
the water passes off to the atmosphere. The quantity of water that can be
heated is only limited by the amount of steam and water that can be
brought together. The steam condensed in heating the water is saved and
utilised for boiler feed. An open heater should m provided with an effl-
eient oil-separator, a large settUns-chamber or hot well in which, if desired,
a filtering bed of suitable materiu can be placed to insure the removal from
the water, of all the impurities held in suspension, a device for skim-
ming the surface of the water to remove the Impurities floating on the water,
and a large blow-off opening placed at the lowest point in the neater.
The eloeed heater is made with a wrought-iron or steel cylindrical shell
and cast-orwrought-iron heads, having iron or brass tubes inside, set in
tube plates so as to make steam- and water-tight Joints, provision being made
Tor the expansion and contraction of the tubes. According to the particular
design of the heater, the exhaust steam passes through or around the tubes.
the water being on the opposite of the walls of the tubes. The steam and
water are separated by metal through which the heat of the exhaust steam
is Innnnitted to the water. As an oil-separator Is very seldom attached to
a closed heater, the steam condensed in heating the water is wasted. The
quantity of water that can be heated is limited by the amount of heat that
can be transmitted through the tubes. The ^ciency of heat transmission
Is decreased by the coati^ of oil that covers the steam side, and the crust
of scale that eoats the water side of the tubes. Ko provision can be made
for purifying the water in a closed heater, as the corstant circulation of the
water prevents the impurities from settling. The impurities that are in the
water pass on into the boiler. Purification must be done by means of an
auxiliary apparatus.
When used with a condenser, the feed water heater will Increase the
Tacuum 1 to 2 inches ; when used with cold feed water, the economy is in-
ereased from 7 to 14 per cent ; if feed water is from a hot well, 7 to 8 per cent.
Two things are very essential to the successful vrorking of all heaters,—
they must be kept clean from scale and oil deposits, and snfilcient exhaust
steam must be sent through them.
The probability of there being much scale ingredients thrown down in a
closed heater where temperature never exceeds 2uf> F., and in an open heater
where temperature approaches more nearly to steam temperature, is shown
by this table.
1376
STBAIC
Temperatvre* at whieh toalo-f onnii^f ingredients are preeipitaied :
Carbonate of lime 17e»-M8<^ F.
Chloride of maffnesium S12<>-S57^ F.
Sulphate of lime aM^* F.-4a4» F.
Chloride of Bodium a84« F.-^38i«> F.
The ratins of a feed-water heater of the closed type is a subject
-which little haa been written, but the common rule is to glre ^ sqasre
of heating surface for one boiler horse-power.
In designing, however, the heating surface should be made Iaivs esMf^
or ample to transmit the maximum number of heat units per mutoraM^ '
and then the water velocity should be adjusted to suit the capadtv nnnilwit
For heat transmitted, one well-known manufacturer uses 960 B. T. ITaia
Ear d^pree F. difference of temperature per square foot of heatintfsixrfaee w
our, as a maximum ; other types of heatersvrould use only ISO to SOB. T. t^^
as the maximum.
As the tubes forming the heating surfaoe in olosed heaters as9 jaadsoC
different materials, if we take
Copperas 100
Brass as. . . . ^ . -9^
Wrought iron as
Cast ironas
58
we can readily see that if one-third square foot surface area is right fsr s .
copper pipe, we will need Wot^or if |, or about six-tenths for inm eotk,
per Doiler horse-power.
The power to transmit heat varies not only with the material, Imt also witk
the desiga of the heater, the velocity of ihe water, and water and sleus
capacity of the heater.
The velocity of the water through the heater should be from 100 to 99
feet per minute.
The proportions of open heaters depend Ivgely upon the eliaraeter <rf ite
water used in the heater, for it should have sumcient time to become tkar-
oughly heated and the scale-forming ingredients settled and eliminated '
the feed as it passes out of the heater.
I.T4I. fin NO. r. •IP. TfMf. MB tQ. rr. jmipaok rm
A
S 11
I
10
- T5
• !
« 1
i !
! 8 1
1 S g 1
\ 1
1 1
\ \
I 8 1
t 1
1 !
"*^
i»
'V;
U"^
.
•tK
fV''
•'^
^2
55:
^
^t^
K
rr
^
Sj»^
^
^
^
i7i
Q mtntKTt puuN Txnn HEAT ABSORPTION CURVES
• •" XjMmWATU TUUt
Fio.6.
(W. W. Christie.)
In converting water at 3S« F. into stesan at atmospheric pressure, it leset
be raised to 217" F., the boiling point.
The specific heat of water varies somewhat with its temperature, so thtf lo
raise a pound of water from82°to212<*F.orl80* F., reqptree 180.8 heat nsila.
To convert it into steam, after it has reaohed 212" F., requires MM iMt
uniU, or in all 1 80.8 -f 966.8 = 1146.6 units of heat, thermal tinits.
The saving to be obtained by the use of waste heat, as eachanst sttSK*
heating the water by transfer of some of its heat through metal walk, it
-^cuUted by this formula:
PUMP EXHAUST.
1377
Gain in per eent = —ff^^ = g.?^ ^^ ▼enr nearly.
I whidi J7= total heat in steam at boiler preeeure (above that in water at
320 p.) in B. T. U.
A, = heat lu feed-water (above 929 F.) after heating.
A, = heat in feed-water ^above 32° F.) before beating.
1^ =: temperature of feed-water after heating ^'F.
<i = temperature of feed-water before heating ^F.
tren lfz= 1146.6, L r= 212, t^ = 112, or a dliference of 100<^; and we obtain by
M of the above formula, gain In per cent = 9.37, or for 10'° approximately
07 per cent, for 11° 1.0? per cent, to we may say that for every 11° F. added
> the feed- water temperature by use of the exhaust steam, 1 per oent of
■el saving results.
The table which follows i« taken from " Power."
1/Wmm€m Ataaat, At«am at VO IP^mmdm Cla«s«
II
Temperature of Water Entering Boiler.
i2ir>
130°
140°
IBOo
160°
170°
180O
190°
200°
210°
220°
260°
SEP
7.24
&09
8.96
9.89
10.06
11JS2
12.38
13.24
14.09
14.96
16.81
19.40
«P.6.84
7.69
8.56
9.42
10.28
11.14
12.00
12.87
13.73
14JS0
15.45
18.89
«o
6.44
7.30
8.16
9.08
9.90
10.76
11.62
12.48
13.36
14.22
15.09
18.87
UP
6.03
6.89
7.76
8.64
9.51
10.38
11.24
12.11
12.98
13.86
14.72
17.87
BSP
5.63
6.48
7.37
8.24
9.11
9.99
10.fi6
11.73
12.60
13.48
14.36
17 J8
9P
5.21
6.06
6.96
7.84
8.72
9.60
10.47
11.34
12.22
13.10
13J6
16.86
esp
4.80
5.67
6JS6
7.44
8.32
9.20
10.08
10.96
11.84
12.72
13.00
16.86
TOP
4.38
6.26
6.15
7.03
7.92
8.80
9.68
lOJil
11.45
12.34
13.22
15.84
7BP
3.96
4.84
5.73
6.62
7.61
8.40
9.28
10.17
11.06
11.95
12.84
16.83
«P
3J(4
4.42
C.32
6.21
7.11
8.00
8.88
9.78
10.67
11JJ7
12.46
14.82
850
3.11
4.00
4.90
5.80
6.70
7JS&
8.48
9.88
10.28
11.18
12.07
14.32
900
2.68
3JS8
4.48
5.38
6.28
7.18
8.07
8.96
9.88
10.78
11.68
13.81
96°
2.25
3.15
4.06
4.96
5.86
6.77
7.66
8.67
9.47
10.38
11.29
13.31
U»o
1^1
2.71
3.62
4.53
6.44
6.35
7.25
8.16
9.07
9.98
10.88
12J0
p Bxhsvai.
In many plants the only available exhaust steam oomes from the steam
pmnpe used for elevator service, boiler-feeding, etc. ; or in condensing plants
from the air-pumps, water-oupply, and boiler feed-pumps. It should mso be
remembered that all direct-acting steam pumps are large consumers of
steam, taking several boiler h. p. for each indicated h. p., and that the ex-
haust steam &om them will heat about six times the same quantity by weight
of eoM water, from 60° to 212° F., and that these pumps, or the independent
eondenser pumps, are more economioal when all the exhaust from them is
used for heating feed-water than the best kind of triple expansion condens-
ing engines, with the pumps all the heat not used in doing work can be
eonserved and returned to the boiler in the feed-water, whereas even with
triple expansion engines at least 80 per cent of the total heat in the steam is
earned away in the condensing water.
While the supply of exhaust from these pumps may not be sufBcient to
raise the temperature to the highest point, yet the saving is large and con-
stant.
These results do not take any account of the purifying action In the
''open" heaters on the feed-water, the Improved condition of which, by di-
minlstiing the average deposit within the holler, materially increases Soth
the heeler eapaeity and the eoonemy ; while the more nniform temperature
1378
STEAM.
mooompaiiying the use of a hot feed reducei the repain and lengthcBt
life of aU bolfen.
If the quantity of water paning throngh the heater is only what it
ouired to furnish stMim for the engine from which the exhaust oomes,
than four-fifths of this exhaust steam will remain unoondensed. aw
thus heoome available for other purposes, such as heating baUdSags,
systems, etc. ; in which case the returns can be sent bacK to the ooOer I
suitable means.
Performance of a Green Eoonomiaer with a Smoky OoaL
(D. K. Clark, S. E., p, 286.)
From testa by M. W. Grosseteste, covering a period of three wi
Green eoonomiaer, using a smoke-making OMil. with a fwwiitant rate oi <»»
bostlon under the boilers, it is apparent that there is a i^eat adTantafp
cleaning the pipes daily — the elevation of temperature having beea
creased by it from 88P to 163°. In the third week, without cleaning, the u^
vation of temperature relapsed in three days to tne level of the first weakj
even on the first day it was quickly reducea by as mueh as half tke ci
of relapse. By cleaning the pipes daily an increased elevation of temj
ture of 65° F. was obtained, wnUst a gain of 6 % was effected in the
tive efficiency.
The action of Green's eoonomiaer was tested by M. W. Grosseteste for
period of three weeks. The apparatus consists of four ranges of
pipes, 6^ feet high, M inches in diameter outside, nine pipes In ead
connected at top and bottom by horisontal pipes. The water enters all
tubes from below, and leaves them from above. The system of p~ ~
enveloped in a brick casing, into which the gaseous products of eoml
are introduced from above, and which they leave irom below. The pi|
are cleared of soot externally by automatic scrapers. The capacity
water is 2i cubic feet, and the total external heatinMurfaoe is 390 1
feet. The apparatus Is placed in connection with a bmler having 3K i
feet of surface.
Ort€n*$ EconomA»er,—JienUtt of Experimentt on its EUfMencM as 4|Mrf|
by the StaU qf the Swfaee,
(W. Grosseteste.)
Temperature of Feed-
Temperatere of On-
water.
eous Products.
TncB.
February and March.
Enter-
Leav-
Euter-
I«ea.v-
ing
Feed-
ing
Feed-
Diffei^
enee.
pe
FmL
Tmrn-
heater.
heater.
heater.
heater.
Fahr.
Fahr.
Fahr.
VnhT.
FUir.
Vikr.
1st Week
TSJGP
161 Jjo
88.0°
848°
961°
5r
2d Week
77.0
»0.0
163.0
882
297
» .
8d Week — Monday . .
73.4
106.0
122.6
831
29« , 517 1
Tuesday . .
73.4
181.4
106.0
sn
300
66
Wednesday
79.0
178.0
90.0
._-
Thursday .
80.6
170.6
90.0
062
929
Ol
Friday . .
Saturday .
80U}
16B.0
88.4
889
338
6Q
70.0
173.4
93.4
901
asi
SSD
Ist Week.
Coal consumed per hour 214 lbs.
Water evaporated from 32° F. per hour 1424
Water per pound of coal ...... 6.66
2d Week.
216 lbs.
1625
7M
SdWcA.
6.76
FUEL ECONOMIZERS.
1379
The "FxuH Eoonomiier CompanyjJCatteawui, K.T., describe the eonitmo-
tion of Green*8 economizer, thus: The economizer consute of a series of sets
of cast-iron tubes aboat 4 Inches in diameter and 9 feet in length, made in
sections (of various widths) and connected by ** top " and " bottom headers,"
these again being coupled by " top " and ** bottom branch pipes " running
lengthwise, one at the top and the other at the bottom, on opposite sides
and outside the brick chamber which encloses the apparatus. The waste
gasee are led to the economizer by the ordinary flue from the boilers to the
chimney.
The feed-water is forced into the economizer by the boiler pump or in-
jector, at the lower branch pipe nearest the point of exit of gases, and
emerges from the economizer at the upper branch pipe nearest the point
where the gases enter.
Each tube is provided with a geared scraper, which travels continuously
up and down the tubes at a slow rate of speed, the object being to keep the
external surface clean and free from soot, a non-conductor of heat.
The mechanism for worldng the scrapers is placed on the top of the eoon-
omizer, outside the chamber, and the motive power is supplied either by a
belt from some convenient shaft or small independent engine or motor.
The power required for operating the gearing, however, is very small.
The apparatus is fitted with blow-offand safety valves, and a space is pro-
vided at the bottom of the chamber for the collection of the soot, which is
removed by the scrapers.
One boiler plant equipped with the Green economizer gave, under test,
these results.
The total area of heating surface in the plant was 8,126 square feet, and
the number of tubes in the economizer 100. The results were as follows: —
Partio^ulars of Test.
1. Duration of test hours
2. Weight of dry coal consumed lbs.
3. Percentage of ash and refuse . . . per cent
4. Weight of coal consumed per hour per square
foot grate surface lbs.
5. Weight of water evaporated lbs.
6. Horse-power developed on basis of 30 lbs. per
h.p. fed at 100° ana evaporated at 70 lbs., h.p.
7. Average boiler pressure (above atmosphere),
lbs.
8. Average temperature of feed-water entering
economizer deg. Fahr.
9. Average temperature of feed-water entering
boilers deg. Fahr.
10. Number of degrees feed-water was heated by
economizer deg. Fahr.
11. Average temperature of flue gases entering
economizer d^. Fahr.
12. Average temperature of flue gases entering
chimney deg. Fahr.
13. Number degrees flue gases were cooled by econ-
omizer d^. Fahr.
14. Lbs. water evaporated per lb. of coal, as ob-
served
15. Equivalent evaporation per lb. of coal from
and at 212°
16. Percentage gained by using the economizer
per cent
Econo-
mizer
working,
Dec. 16.
Econo-
mizer not
working,
Dec. 16.
11 JS
8,743
7.6
11.5
9,694
7.7
16.2
84/)78
16.8
82,726
247.0
243^ '
68.2
67.2
84.2
• « •
196.2
82.0
112.
• • •
436.
• • •
279.
462.0
166.
■ • •
9.617
8J5S3
11.204
9.965
12J6
• . •
The steam in this test contained 1.3 per cent of moisture.
(
1380
STEAM.
W. 8. Hatton gives the following results of tests of a steam boiler vidk
and without an economizer.
1
With Boon-
omixer.
1
ViSlMtt
EeoBO-
misB.
Duration of test* hours
ids
•
7866
68
88
137
618
386
253
10.613
28.9
10286
57
• • •
S
• • •
• • •
eis
• • ■
Weight of ooal, pounds
Steam pressure, pounds
Temp, water entering economiser, degrees . .
*• boiler, d^gnMs . . . .
Degrees feed-water heated by eeonomlser . .
Temp, gases entering economiser, degrees . .
" ** ** chimney, degrees . . .
Degrees gsses oooled by economisMr ....
Evaporation per lb. ooal, from and at 212°, poux
Saving by eoonomiaer, per cent
i*a Fael Sconoailser. — Clark gives the following arenaei^j
suits of oomparatiTe trials of three twilers at Wigan used with and viira|
economisers :
Without Witk
Eoonomiaen. SeoacoBiat
Goal per square foot of grate per hour . . . 21.6 21.4
Water at 100° evaporated per hour .... 7SJK T9S1
Water at 212° per pound of coal 9.00 WM
Showing that in burning equal quantities of coal per hour the vwoidaKfdi
evaporation Is increased 9.3% and the efficiency of evaporation 10% by tb* ,
addition of the economiser. ^
The average temperature of the gases and of the feed-water before >■■.
after passing the economizer were as follows :
With 6-f t. grate. With 44L t"^ •
Before. After. Before. Aft&i
Average temperature of gases ... 049 340 601 3n
Average temperature of feed-water . 47 157 41 »>
Takinff averages of the two grates, to raise the temperature of thef«^{
water 100°, the gases were cooled down 280°.
0TCA1II SKPAHATOKA.
Carefully conducted experiments have shown that water, oil. or
liquids passing through pipes along with steam do not remain tnoro _
mixed with the steam itself, but that the major portion of thee« liquids i
lows the inner contour of the pipe, especially In the case of hoi
pipes.
From this it would necessarily follow that a rightly designed separator^
meet these conditions must interrupt the run of the liquid by breakiittr
continultv of the pipe, and offering a receptacle into which the liqmai
flow freely, or fall by gravity — that this appliance must further wtf^
opportunity for the liquid to come to rest out of the current of steam, nrl
is not enough to simply provide a well or a tee in the pipe, since the cur^j
would Jump or draw the liquid orer this opening, especially if the vewelVf
was high. I
It is also evident that means must be provided in this applianoe for iirttf||
rupting the progress of those particles of the liquid which are traveling}
the current of the steam, and do this in sueh a way that theee partidei ^
STEAM SEPARATORS.
1381
ibo be detained and aU<rRTOd to fall Into the reeeptaole proTlded, which
receptacle moat be fully protected from the action of the current of the
■team ; otherwise, the separated particles of water or oil will be picked
Bp and carried on past the separator.
To prerent the current from jumping the liquid over the well, and to
interrupt the forward morement of tnose particles travelinc in or with the
Borrent, it follows that some obstruction must be interposea in the path of
the corrent.
Steam separators should always be placed as near as possible to the steam
Inlet to the cylinder of the engine. Oil separators are placed in the run of
the exhaust pipe from engines and pumps, for the purpose of removing the
oil from the steam before it is used in any way where tlie presence of oil
would cause trouble.
Prof. B. G. GMpentor conducted a series of tests on separators of seyeral
makes in 1801. The following table shows results under Tarious oonditiona
of moisture :
Test with Steam of about 10%
of Moisture.
Tests with Varying Moisture.
o15
3*
Quality ot
Steam
Before.
Quality of
Steam
After.
Efficiency
per cent.
Quality of
Steam
Before.
Quality of
Steam
Aftor.
Arerage
BiBcienoy.
B
A
D
C
B
P
87.0%
90.1
80.6
90.6
88.4
88.9
1
98.8%
98.0
05.8
93.7
90.2
92.1
90.6
80.0
69.6
33.0
15.5
28.8
66.1tofl74(%
51.9 " 98
72.2 " 96.1
67.1 " 96.8
68.6 '* 98.1
70.4 " 97.7
97.8 to 99%
97.9 •• 99.1
96.5 " 98.2
93.7 " 98.4
79.3 " 98.6
84.1 " 97.9
87.6
76A
71.7
63.4
86.9
28.4
Conclusions from the tests were : 1. That no relation existed between the
Tolume of the seyeral separators and their efficiency.
2. Ko marked decrease in pressure was shown by any of the separators,
the most being L7 lbs. in E.
3. Although chansed direction, reduced velocity, and perhaps centrifugal
force are necessary for good separation, still some means must be provided
to lead the water out of the current of the steam.
A test on a different separator from those given above was made by Mr.
Charles H. Parker, at the Boston Edison Company's plant, in November,
1897, and the following results obtained :
Length of run 3-4 hn.
Average pressure of steam 158 lbs. per sq. in.
Temperature of upper thermometer in calorimeter on
outlet of separator 368.5<' F.
Temperature of lower thermometer in calorimetor on
outlet of separator 291.7^'F.
Komial temperature of lower thermometer, when stoam
is at rest 292.9^ F.
Degrees cooling as shown by lower thermometer ... 1.2PF,
Moisture in steam delivered by separator as shown by
cooling of lower thermometor 06 per cent.
Water discharged from separator per hour ,62 lbs.
Steam and entrained water passing through engine, as
shown by discharge from air pump ox surface con-
denser . I . . . . 7369 lbs.
Steam and entrained water entering separator .... 7411 lbs.
Moisture taken out by separator 72
Total moisture in steam (.06 plus .72) 78 per eent.
SAciency of separator 92.3 per oent*
1382
STEAM.
atiOA of irelcMt, etc., for I<OTor Bmimty^WmMw,
•Let fr= weight of ball at end of lever, in pounds ;
10 = weight of lever itself, in pounds ;
F= weight of valve and spindle, in pounds ;
L =z dL^tanoe between fulcrum and center of ball, in indies ;
{ = dutance between fulcrum aiid center of valve, in inches :
g = distance between fulcrum and center of gravity of lever, in iacte;
A = area of valve, in square inches ;
P = pressure of steam, in pounds per square inch at whieh valve vul
open.
Then PAx 1= W x L + vf x g+ f^X li
whence P = ^^^ ;
PAl-wg—ri,
L
W^ -, ,
, PAl—wg—Vl
X = ^
EzAMPLK.— Diameter of valve, 4 inches ; distance from falcrum to<
of ball, 36 inches ; to center of valve. 4 Inches ; to center of gravity of leter,
16 inches ; weight of valve and spindle, 6 lbs. ; weight of lever, 10 lbs.; i«>
quired the weight of ball to make the blowing-off preesore 100 lbs. per
square inch ; area of 4-inoh valve =r 12J$66 square Inches. Then
-_ PAl-x^— VI 100 X 12J566 x 4— 10 X 16 — 6 X 4 ,^^,^
W S= ———————— s: ;;: ISli* IBB.
(Bule of U. 8. Supervising Inspectors of Steam-vessoU as M^mflnfiirf um.)
The distance from the fulcrum to the valve-stem must in no ease be leo
than the diameter of the valve-opening ; the length of the lever ninstw^ ta
more than ten times the distance from the fulcrum to the valve-stera ; ths
width of the bearings of the fulcrum must not be less than three-quartan
of an inch ; the len^h of the fulcrum-link must not be less than four indMK
the lever and fulcrum-link must be made of wrought iron or steel, axMl tbe
knife-edged fulcrum points and the bearings for these points most be made
of steel and hardened : the valve must be guided by its spindle, both abon
and below the ffronnd seat and above the lever, through supports eitker
made of composition (gun-metal) or bushed with it ; and the spindle tmA
flt loosely in the bearings or supports.
Jiever safety-valves to be attached to marine boilers shall have an area of
not less than 1 square inch to 2 square feet of the grate surfaee in tke
boiler, and the seats of all suoh safety-valves shall have an angle of ineliss-
tlon of ASP to the center line of their axes.
Spring-loaded safety- valves shall be required to have an area of not k*
than 1 square inch to 3 square feet of grate surface of the boiler, exeepi »
hereinafter otherwise provided for water-tube or coll and seotional bmlen.
and e«<!h spring-loaded valve shall be supplied with a lever that will raise tlw
valve from its seat a distance of not less than that equal to one-ei^th tk«
diameter of the valve-opening, and the seats of all suoh safety-valves sl»n
have an angle of inclination to the center line of their axes af46<». iSi
spring-loaded safety-valves for water-tube or ooil and sectional bcOa*
required to carry a steam-pressure exceeding 175 lbs. per square inch shsQ
be required to have an area of not less than 1 square inch to 6 souare ittK
of the ffrate surface of the boiler. Nothing herein shall be oonsCrued so ss to
grohiblt the use of two safety-values on one water-tube or ooil and sectional
oiler, provided the combined area of such valves is equal to that reouiisd
by rule for one such valve. ^
^
SAFETY VALVES.
1383
£very boiler when iired separately, and every set or series of boilers when
pl»c^a over one fire, shall have attached thereto, without the interpoeition
or tuxy other Tslve, two or more safety-valves, the aggregate area of which
sliAll liave such relations to the area of the grate and the pressure within
tkx^ l>ollor as is expressed in schedule A.
ScBJCi>ULE A.— Least aggregate area of safety-valve (being the least se^
tioxiflkl area for the discharge of steam) to be placed upon all staitionarj
boilers with natural or chimney draught (see note a).
22JSg
^"" P-|-8.e2*
Ia ^rlxicb A is area of combined safetv- valves in inches ; O is area of grate In
sqnfikre feet ; P is pressure of steam in poxmds per square inch to be carried
In tbe boiler above the atmosphere.
Xlie following table fldvee the results of the formula for one square foot of
grate, an applied to boQers used at dliferent pressures :
J^reesures per square inch :
10 20 30 40 60 60 70 80 90 100 110 120 IM 176
VsklTe area in square Inches corresponding to one square foot of grate :
1^ .79 .58 ^ .38 .33 .29 .25 .23 .21 .19 .17 .14 .12
£^OTK a.] — Where boilers have a forced or artiflcial draught, the inspeo-
tor must estimate the area of grate at the rate of one square foot of grate
sarf ace for each 16 lbs. of f uelbumed on the average per hour.
Tlie various rules given to determine the proper area of a safety-valve do
not take into account the effective discbarge area of the valve. A correct
rale should make the product of the diameter and lift proportional to the
welsht of steam to be discharged.
IMLr. A. O. Brown {The Indicator and it» Practical Working) gives the fol-
lowing as the lift of the lever safety-vslve for 100 lbs. gauge pressure. Tak-
\n^ the ^ective area of opening at 70 per cent of the product of the rise and
the circumference
I>iRTneter of valve, inches 2218 314 4^5 6
Rise of valve, inches . . .0583 .0^ .0607 .0492 .0478 X)462 U)446 .043
For "pop" safety-valves, Mr. Brown gives the following table for the
rise, effective area, and quantity of steam discharged per hour, taking the
effective area at 50 per cent of the actual on account of the obstruction
wblch the Hp of the valve offers to the escape of the steam.
IM. valve in.
1
U
2
.%
3
H
4
*L
6
6
Uf t inches.
.126
.160
.175
.225
.260
.276
.300
.826
.375
Area,8q.in.
.196
.354
JS60
.786
1.061
1JI76
1.728
2.121
2J!n3
3.636
Oange-
Bteam discharged per hour, lbs.
press.
30 lbs.
474
856
1330
1897
2663
3325
4178
6128
6173
8678
60
669
1209
1878
2680
3620
4695
6901
7242
8718
12070
70
861
1556
2417
3450
4660
6144
7596
0324
11220
16536
90
1050
1897
2947
4207
5680
7370
9200
11365
13686
18045
100
1144
2065
3206
4580
6185
8322
10080
12375
14896
90626
120
1332
2405
3736
6332
7202
9342
11735
14410
17340
24015
140
1516
2738
4254
6070
8200
10635
13365
16406
19746
27340
160
1606
3064
4760
6794
9175
11900
14955
18355
22096
30606
180
1883
3400
5283
7540
10180
13260
16505
20370
24620
83960
200
2062
3724
5786
8258
11150
1
14466
18175
22310
26855
37186
If we also take 30 lbs. of steam per hour, at 100 lbs. gauge-pressure = 1
h. p., we have from the above table :
Diameter inches .1 U 2 21 33144*6 6
Horse-power . . 38 09 107 iS 206 217 836 412 496 687
1384
STEAM.
A boiler harinff ample grate surfaee and strong draft may geaeiaie
doable the auazitlty of steam its ratins calls for ; thes^ore in di
the proper sue of safety-valve for a Doiler this fact should be
eonslderation and the eifective discharge of the valre be doable the :
ateam-prodacing capacity of the boiler.
The Consolidated Safety-valve Go.'s olronl«r gives the foUowtng
capacity of its nickel-seat ** pop " safety-valves :
Size, in . .
Boiler (from
H.P. 1 to
1
8
10
15
30
2
36
60
76
3
76
100
1%
126
4
126
160
WO
lib
miimLMB warn coivmrcTnio boulbr
The Committee of the A. 8. M. E. on Boiler^este reoommended tiie fol-
lowing revised code of roles for conducting boiler trials. (Trans. toL zx.
See also p. 34, vol. xxi, A. 8. M. £., for latest code.
Cods of 1897.
iVef tMinoriet to a Triai.
I. DeiernUne cU the outaet the speciflc object of the proposed trial, wl
it be to ascertain the capacity of the boiler, its efficiency as a steam
ator, its efficiency and its defects under usual working oonditlona, thc~
omy of some particular kind of fnel, or the effect of chaiweB of
proDortion, or operation ; and prepare for the trial accordingly.
II. Examine the boUer^ both outside and inside ; ascertain the dimearioei
of grates, heating surfaces, and all important parts; and make a faB
record, describing the same, and illustrating special features by aketeheB.
The area of heating surfaces is to be computed from the outside tuaoMts^ol
water-tubes and the inside diameter of nre-tubes. All surfaees belov tte
mean water level which have water on one side and products of combsslim
on the other are to be considered water-heating surface, and all surfaea
above the mean water level which have steam on one side and products of
combustion on the other are to be considered as superheating surface.
III. Notiee the general condition of the boiler and its equipment, ai^
record such facts in relation thereto as bear upon the objects in view.
If the oblect of the trial is to ascertain the maximum economy or eapa>
city of the boiler as a steam generator, the boiler and all its appurtenaneM
should be put in first-class condition. Clean the heating surfaoe indde awl
outside, remove clinkers from grates and from sides of the f uraaoa. Re-
move ail dust, soot, and ashes from the chambers, smoke connectlcms, sad
flues. Close air leaks in the masonry and poorly-fltted deaning-doon. Sea
that the damper will open wide and close tight. Test for air leaks by firiaf
a few shovels of smoky fuel and immediately closing the damper, obssrriif
the escape of smoke tnrouffh the crevices, or by passing the flame of a eaa-
^e over cracks In the brickwork.
rv. Determine the character of the coal to bo used. Tot tests of tiEiecft-
dency or capacity of the boiler for comparison with other boilers the «al
should, if Dossible, be of some kind which is commercially regarded as attia-
dard. For New England and that portion of the country east of tbe AUc^May
Mountains, good anthracite egg coal, containing not over 10 per cent of adu
and semi-bituminous Clearfield (Pa.), Cumberland (Md.), and Pocahoaai
rVa.) coals are thus regarded. West of the Allegheny MonntainB. Pwa-
hontas fVa.), and New Klver (W. Ya.) semt-bitumlnous, and Tonghiog^ieaT
or PittsDurff bituminous coals are recognized as standards.* l%«e is ao
special grade of coal mined in the Western States which is widely reeef-
mzed as of superior quality or considered as a standard coal for boiler ten-
ing. Big Muddy Lump, an Illinois coal mined in Jackson Ccmnty, TtU k
• 7^^« cOate are selected because they are about the only coals ttfhieh
tain the essentials qf excellence qf qwuity^ adaptdbiUfy to varioms kinds ^
fkumcteest grates, boilers, and methods qf firing, and vnde dietribmHon em
general aceestilnlity in themarteU.
RULES FOR CONDUCTING BOILER TESTS. 1386
•nggeeted as being of svffloiently hi^ grade to answer the requirements in
diBUicta where it Is more conveniently obtainable than the other ooals men-
tioned above.
For teats made to determine the perfonnanoe of a boiler with a particolar
kiiMi of coal, such as may be specified in a contract for the sale of a boiler,
the coal used should not be higher in ash and in moisture than that speci-
fied, since increase in ash and moisture above a stated amount is apt to
eaoae a falling oif of both capacity and economy in greater proportion than
iho proportion of such increase.
V. M9tabli»h thf correctneits o/all appctrahu used in the test for weighing
and measuring. These are :
1. Scales for weighing coal, ashes, and water.
2. Tanks, or water meters lor messuring water. Water meters, as a rule,
alioold only be used as a check on other measurements. For accurate work,
Uie water should be weighed or measured in a tank.
3. Thermometers and pyrometers for taking temperatures of air, steam,
feed-water, waste gases, etc.
4. Preasure gauges, draft gauges, etc.
The kind and location of the various pieces of testing apparatus must be
left to the judgment of the person conducting the test; always keeping in
mind the main object, i.e., to obtain authentic data.
YI. See that the boiUr is thoroughly heated before the trial to its usual
working temperature. If the boiler is new and of a form provided with a
brick setting, it should be In regular use at least a week oefore the trial,
so aa to dry and heat the walls. If it has been laid off and become cold, is
ahoald be worked before the trial until the walls are well heated.
VII. The boiler and connection* should be proved to be firee from leaks
before beginning a test, and all water connections.including blow and extra
feed pipes, should be disconnected, stopped with blank flanges, or bled
through special openings beyond the valves, except the particular pipe
through wnlch water is to be fed to the boiler during the triaL During the
test the blow-off and feed-pipes should remain exposed.
If an Injector Is used, it anould receive steam directly through a felted
pipe from the boiler being tested.*
If tbe water Is metered after it passes the injector, its temperature should
be taken at the point at which it enters the boiler. If the quantity is deter^
mined before it ffoes to the injector, the temperature should be determined
on the suction side of the injector, and if no change of temperature occurs
oUier than that due to the injector, the temperature thus determined is
properly that of the feed-water. When the temperature changes between
the injector and the boiler, as by the use of a heater or by radiation, the
temperature at which the water enters and leaves the Injector and that at
which it enters the boiler should all be taken. The final temperature cor-
rected for the heat received from the injector will be the true feed-water
temperature. Thus if the injector receives water at BOP and delivers it at
lafP into a heater which raises it to 210^, the corrected temperature is 210 —
(120 — 50) =1400.
See that the steam main is so arranged that water of oondensation eaiK
not run back into the boiler.
Tin. Starting and Stopping a Test. — A test should last at least ten hours
of continuous runnins, but, if the rate of combustion exceeds 26 pounds of
eoal per square foot of grate per hour it may be stopped when a total of 200
pounds of coal has been burned per square root of grate surface. A longer
test may be made when it is desired to ascertain the effect of widely yary^
ing conditions, or theperformanoe of a boiler under the working conditions
ofa prolonged run. The conditions of the boiler and furnace in all respects
should be, as nearly as possible, the same at the end as at the beginning of
the test. The steam pressure should be the same; the water level the
• In feeding a boiler undergoing teet vfith an in^eektr tedting steam ftmn
another boiler f or the main steam pipe from severai boilers , the evaporative
results may be modified by a difference in the quality <^ the steam from such |
sowree compared with that supplied by the boiler being tested^ ana in some I
oases the connection to the ii^jeetar may act as a drip for the main steam pipe. \
Ifttis known that the steam ffvm the main ptoe is of the same qualiiu as thai
fStmished by the boiler undergoing the testt the steam may be taken from such
maimptpe.
1386 BTEAM.
■Aine ; the fire upon the grates ehould be the same In qnantltj and l^..
tion ; and the waUa, floee, etc., should be of the same temperature. Tv»
methods of obtaining the desired equality of conditions of tne lire an ha
usediYls. : those which were called in the Code of 1885 "the stsBiMft
method ** and *' the alternate method," the latter beiitg employed when ft
is inconvenient to make use of the standard method.
IZ. Standard iferJkod. ^ Steam being raised to the vorkinff |ui— ^
remore rapidly all the lire from the grate, close the damper, dean thesA-
pit, and as quickly as possible start a new fire with weighed wood aaicoii,
noting the tune and the water level while the watar Is m « qnieseest ilsfe^
Just before lighting the fire.
At the end of the test remove the whole fire, which has been bmrned kv,
clean the grates and ash-pit, and note the water level when the watcz is im
a quiescent state, and record the time of banting the fire. The water level
should be as nearly as possible the same as at the beglnnlQg of the tolL
If it is not the same, a correction should be made by ccnnputatioii, and Ml
by operating the pump after the test is completed.
X. JUenwU Method. — The boiler being thoroajghly heated bj a pnSMat
nary run, the fires are to be burned low and well cleaned. Mote the amo^
of coal left on the grate as nearly as it can be estimated ; note the pcest—
of steam and the water leveL and note this time as the time of atarting iLe
test. Fresh coal which has been weighed should now be flred. Ti» sah*
gts should be thoroughly cleaned at once after starting. Before the end of
>e test the fires should be burned low. Just as before the start, and ths
fires cleaned in such a manner as to leave the bed of ooal of.tha saiM
depth, and in the same condition, on the srates, as at the start. Tht
water level and steam pressures should previously be brought as nearly m
possible to the same point as at the start, and the time of ending of the test
should be noted Just oef ore fresh coal is fired. U the water level fe not the
same as at the start, a correction should be made by computation, and not
by operating the pump after the test is completed.
XI. Un^ormUy of Oondiiions. — In all trials made to ascertain maxlouM
economy or oapaoify, the conditions should be maintained nniformly coa-
stant. Arrangements should be made to dispose of the steam so that tht
rate of evaporation may be kept the same from beginning to end. Thh
may be accomplished in a single boiler bv carrying the steam throu^ s
waste steam pipe, the discharge from which can be regulated as desired.
In a battery of Doilers, in which only one is tested, the draft can be r^o-
lated on the remaining boilers, leaving the test boiler to work under a eo»>
stant rate of production.
Uniformity of conditions should prevail as to the pressure of steam, tbs
height of water, the rate of evaporation, the thickness of fire, the times of
firing and quantltv of coal fired at one time, and as to the interVals betwesa
the times of cleanlnff the fires.
XII. Kemktfi the Reoorde, — Take note of every event connected with fks
progTMS of the trial, however unimportant it may appear. Beeoid the
time of every occurrence and the time of taking every weight and evsy
observation.
The coal should be weighed and delivered to the fireman In equal propor-
tions, each sufficient for not more than one hour's run, and a freshportlaa
should not be delivered until the previous one has all been flredL The time
required to consume each portion should be noted, the time bei^ recorded
at the instant of firing the last of each portion. It Is desirable that at the
same time the amount of water fed Into the boiler should be accnratd^
noted and recorded, Including the height of the water in the botler, and the
average pressure of steam and temperature of feed during the time. B7
thus recording the amount of water evaporated by suoceaalveportloas of
ooal, the test may be divided into several periods if desired, ana the degree
of uniformity of combustion, evaporation, and economy aniUyzed for eacik
period. In addition to these records of the ooal and the feed-water, hiJf
hourly observations should be made of the temperature of the feed-water,
of the flue gases, of the external air in the boiler-room, of the temperature
of the furnace when a furnace pyrometer is used, also of the pressure of
steam, and of the readings of the Instruments for determining the rooistore
in the steam. A log should be kept on properly prepared blanks eontalnhig
columns for record of the various observauons.
When the " standard method '* of starting and stopping the test ts used.
KULE8 FOR CONDUCTING BOILER TESTS. 1387
tta hourly rate of oombiutlon and of eyaporaUon and the horse-pover may
M computed from the records taken dunng the time -when the flree are in
Mttre condition. This time is somewhat less than the actual time which
•laiiani between the beginning and end of the run. This method of
eomputatlon is necessary, owing to the loss of time due to kindling the fire
at t&e beodnning and borningit out at the end.
XIII. %/ucUit5 of Steam. —-The percentage of moistnre in the steam shoold
be deterniined by the use of either a throttling or a separating steam calor-
bneter. The sampling nozsla should be placed in the vertical steam pipe
ttaliig from the boiler. It should be made of ^inch pipe, and should extend
aeroes tbe diameter of the steam pipe to wlthfii half an Inch of the opposite
■Ide, being closed at the end and perforated with not less than twenty }-inch
faolee equally distributed along and around its cylindrical surface, but none
o# theoe holes should be nearer than | inch to the inner side of the steam
pipe. The calorimeter and the pipe leading to it should be well covered
vfth felting. Whenever the indications of the throttlins or separating
ealozimeter show that the percentf^^e of moisture is irregular, or occasion-
ally in excess of three per cent, the results should be checked by a steam
separator placed in the steam pipe as close to the boiler as convenient, with
a calorimeter in the steam pipe just beyond the outlet from the separator.
The drip from the separator should be caught and weighed, and the per-
oentitf e of moisture computed therefrom added to that shown by the
calorimeter.
Superheating should be determined by. means of a thermometer placed in
a mercury well inserted in the steam pipe. The degree of superheating
should be taken ss the difference between the reading of the thermometer
for superheated steam and the readings of the same thermometer for satu-
rated steam at the same pressure as determined by a special experiment,
and not by reference to steam tables.
XIV. Sampling the Coal and Determining its Moietwe, — As each barrow
load or fresh portion of coal is taken from the coal pile, a representative
shovelful is selected from it and placed in a barrel or box in a cool place
and kept until the end of the trial. The samples are then mixed and
broken into pieces not exceeding one inch in diameter, and reduced by the
process of repeated quartering and crushing until a fljial sample weighing
about five pounds is obtained, and the size of the larger pieces is such that
they will pass through a sieve with ^inch meshes. From this sample two
one-quart, air-tight glass preserving Jars, or other air-tight vessels which
will prevent the escape of moisture from the sample, are to be promptly
filled, and these samples are to be kept for subsequent determinations of
moisture and of heating value, and for chemical analyses. During the
process of quartering, when the sample has been reduced to about 100
pounds, a quarter to a half of it may be taken for an approximate determi-
nation of moisture. This may be made by placing it in a shallow iron pan, not
over three inches deep, carefully weighing it, and setting the pan in the
hottest place that can be found on the brickwork of the boiler setting or
fiuee, keeping it there for at least twelve hours, and then weighing it.
The determination of moisture thus made is believed to be approximately
accurate for anthracite and semi-bituminous coals, and also tor Pittsburff
or Youghiogheny coal ; but it cannot be relied upon for coals mined west ox
Pittsburg, or for other coals containing inherent moisture. For these latter
coals it is important that a more accurate method be adopted. The method
recommended bv the Committee for all accurate tests, whatever the char-
acter of the coal, is described as follows :
Take one of tke samples contained in the glass Jars, and subject it to a
thorough air-drying in a warm room, weighing it before and after, thereby
determining the quantity of surface moisture it contains. Then crush the
whole of it by running it through an ordinary coffee mill, adjusted so as to
produce somewhat coarse grains (iou than t^inoh), thoroughly mix the
crushed sample, select from it a portion of from 10 to 60 grams, weigh it in
'a balance which will easily show a variation as small as 1 part in 1,000, and
dry it in an air or sand bath at a temperature between 240 and 280 degrees
Fahr. for one hour. Weigh it and record the loss, then heat and weigh it
again repeatedly, at Intervals of an hour or less, until the minimum weight
has been reached and the weight begins to increase by oxidation of a por-
tion of the coal. The difference between the original and the minimum
weight is taken as the moisture in the air-dried coal. This moisture should
1
1388 BTEAM.
preferably be made on duplicate samples, and the results should sgras
within 0.3 to 0.4 of one per cent, the mean of the two determJn&tkms beam
taken as the correct result. The sum of the percentage of moisturs thv
found and the percentage of surf ace moisture previously determined h ^s
total moisture.
XV. TncUment qf Aahea and i?e/Vt««.— The ashes and refuse are to bs
weighed in a dry state. For elaborate trials a sample of the same sho^
be procured and analyzed.
XVI. CaUnifie Test$ and AnalyHs qf OMz/.^-The quality of the fad
should be determined either by heat test or by analysis, or by both.
The rational method of determining the total heat of combostlaBiita
bum the sample of coal iaan atmosphere of oxygen gas, the eoal to In
sampled as directed in Article XI V. of this code.
The chemical analysis of the coal should be made only by an expat
chemist. The total neat of combustion computed from the results of tha
ultimate analysis may be obtained by the use of Dolong's formula (witb
constants modified by recent determinations), tIz. : 14^600 C + fiMtt
( H— ^ } + 4>000 S, in which C, H, O, and £ refer to the proportiow of
carbon, hydrogen, oxygen, and sulphur respectively, as determiaed by tbe
ultimate analysis.*
It is recommended that the analysis and the heat test be each made \/j
two independent laboratories, and the mean of the two results, if there a
any difference, be adopted as the correct figures.
It is desirable that a proximate analysis should also be made to detensiM
the relative proportions of volatile matter and fixed carbon in the coaL
XVII. Analysis of Flue Oases. — The analysis of the flue gases is an eap^
dally valuable method of detemilninff the relative value of different nteifc-
ods of firing, or of different kinds of furnaces. In making these analyacs,
great care should be taken to procure average samples — since the ooaoso*
sition is apt to vary at different points of the flue. The composition is aao
apt to Vary from minute to minute, and for this reason the drawings of gae
should last a considerable period of time. Where complete detemdnatkiBt
are desired, the analyses should be Intrusted to an expert eh^nist. For
approximate determinations the Orsat or the Hempel apparatus may be
used by the ensfneer.
XVIII. SmoEe Observations. — It is desirable to have a uniform system of
determining and recording the quantity of araoke produced where hitaoBi-
nous coal is used. The system commonly employed is to express the decree
of smokiness by means of percentages dependent upon the judgment of tba
observer. The Committee does nut place much value upon a pereeBtafe
method, because it depends so largely upon the personal element, but if
this method is used, it is desirable that, so far as possible, a d^biltion be
given in explicit terms as to the basis and method employed in arrlviag at
toe nercentuge.
XIX. Miscellaneous. — In tests for purposes of scientific researdi, la
which the determination of all the variables entering into the test is de-
sired, certain observations should be made which are in general unneeee-
sary for ordinary tests. These are the measurement of the air supply, the
determination of its contained moisture, the determination of the amoant
of heat lost by radiation, of the amount of infiltration of air through tbe
setting, and (by condensation of all the steam made by the boiler) ol the
total heat imparted to the water.
As these determinations are not likely to be undertaken exeept by engi-
neers of high scleutiflo attainments, it. is not deemed advisable to give
directions ^r making them.
XX. Calculations of Efficiency. —Two methods of defining and caleolal*
ing the efficiency of a boiler are recommended. Tbey are :
■■ -n^ 1 ji >..«. I. 11 Heat absorbed per lb. combustible
1. Efficiency of the boiler = ^ -—. = \^ -. ^^ — -^=-^ .
' Heating value of 1 lb. combustible
A -Bijn . « ^^ L II J A Heat absorbed per lb. coal
2. Efficiency of the boiler and grate = = — -. 1 */, ^ =•
'' Heating value of 1 lb. ooal
• Favre and Silberman give 14^544 B. T. U, per pound carbon : Bertkekt
14,647 B.T.U. Favre ond Silberman give 62,032 B.TM. per potrnd kydny-
gen; Thomson 61,816 B. T.U.
RULES FOR CONDUCTING* BOILER TESTS. 1389
Tbe flxvt of these is sometimes called the efficiency based on combustible,
Bn«i the second the efficiency based on coal. The first is recommended as a
•taindard of comparison for all tests, and this is the one which is miderstood
to be referred to when the word ** efficiency '* alone is used without qualifi-
cation. The second, however, should be included in a report of a test,
to«eth.er with the first, whenever the obiect of the test is to determine the
eflSoiency of the boiler and furnace together with the grate (or mechanical
stoker), or to compare different furnaces, grates, fuels, or methods of firing.
The heat absorbed per pound of combustible (or per pound coal^ is to be
calculated by multiplying the equivalent evaporation from and at 217P
per potmd combustible (or coal) by 966.7* (Appendix XXI.)
XXI. 77k« Heat Balance. — An approximate " heat balance,*' or statement
of the distribution of the heating value of the coal among the several Items
of heat utilised and heat lost, may be included in the report of a test when
aiiAlyBes of the fuel and of the chimney gases have been made. It should
be reported in the following form :
Meat Balance, or Distribution of the Seating Valm of the OonUmstibU,
Total Heat Value of 1 lb. of Combustible B. T. U.
1.
Heat absorbed by the boiler = evaporation from and at
212° per pound of combustible x 965.7.
Loss due to moisture li. coal = per cent of moisture re-
ferred to combustible -r 100 x [(212 — f ) + 966 + 0.48
(T — 212)] (t = temperature of air in the boiler-room,
T= that of the flue gases).
Loss due to moisture formed by the burning of hydro-
gen = per cent of hydrogen to combustible -r 100 x 9
X [(212 — 0 + 906 + 0.48 (T - 212)].
4.* lioes due to heat carried away in the dry chimney gases
= weight of gas per pound of combustible x 0.24 X
(T—t),
CO
6.t Loss due to incomplete combustion of carbon=-
a.
3.
'COt-\-CO
+
per cent (7 in combustible
100
X lO.lfiO.
Loss due to unconsumed hydrogen and hydrocarbons, to
heating the moisture In the air, to raaiation, and un-
accounted for. (Some of these losses may be sepa-
rately itemized if data are obtained from which they
may be calculated.)
Totals
Per
Cent.
100.00
• The weight of gas per pound of carbon burned map be calculated from
the gas analvtia aa follows:
Dm gas per pound carbon = 3 (CO + CO) — — *" v>h%ch COt,
CO, 0,and y are the percentages by volume of the several gases. As the
sampling and analyses of the gases in the present state of the art are liable
to considerable errors, the result of this calculation is usually only an approx-
imate one. The fleat balance itself is also only approximate for this reason,
as well as for the fact that it is not possible to determine accurately the per-
centage of unturned hydrogen or hydrocarbons in thefiue gases.
The weight of dry gas per pound qf combustible is found by multiplying
the dry gas perpouna qf carbon by the percentage of carbon in the combusti-
ble, and dividing by 100.
t CO^ and CO are respectively the percentage by volume of carbonic acid
and carbonic oxide in the Jlue gases. The quantity 10,160 = No, heat units
generated by burning to carbonic acid one pound of carbon contained in coT'
bovAe oadde.
taken u thowrrecl reault. T^e BumotUir '' .-(JTideilfo
found uid the percantHge of •urtace moleU- . . "•* •*• J*" ^^"
total molBtuTB. under tlw hw»nr
XV. Tnatmc«l of Ailut anJ JttftHt.- "K line, wlttw*!*
netghed m a dry ttntt. For elaboraM a. S, ii ra;rMiii^
be procured and analTiKl. jrM(lii«UMk«erm
XVI. Calor'- " — ■ ■--■--^
Calori/lc TeiU and Analfi
"The"ra1
miDed either hf heal
BBiDpLed aa dlncwri in Article
The chemical analriila ot f.
. The total hsal of c
« analyalB
('-.!).-
-i.'^i'
■1-4,000 S, In
oarbon, h^ilrogea, oijgr
two independvnt lab*
any dIDerence, be ■
It U desirable th'," . .
the relative propf .
^fOoD of (he boiler ihoDld be (iTan oa u uma
^[ye . . . irldth . . . length . . . an* . .
ilflixiuiii draft area to grate iiirfaes
rnire by gauge ....
raft between damper and
ratt in fnrnaee . . .
raft or blait In aah-pit
entering heater
mdltlon . . .
wood died In 11
coal aa Bred*.
SuinatmC <if Htood uted intinMi^tkt ^Ira, not luciiiAiif ■■
'avmfrrmfiiTWKtatti'tietiftitai»i'»gaMdataiii)flM,(m
' ia taken U> M t^ual to 0.4 pomul qfaKU, or, in sok fnaU
tired, cu Aai-iii« a teal mlitc H/alvalati to Me tnmnlisti
Utr/romandat212°ptrpoiiiitd(e x 000.7 ^S.TH S.T.CJ.
i
^
^S FOR CONDUCTING BOILER TESTS. 1891
^^^^^ ~*ure in ooal * p«roent.
Z^J*k^^9^. >r^ ^(jidryooal percent
^<^ ~%1 oonsomed lbs.
^?%.^ '^4- ' ^^•
•,:?5^lr/^.7-4r*^ <^ Of Coal. OfCombiutible.
100 per cent 100 per cent,
.cermined '* "
. . . percent.
*^ ,/> '■ • ■ • • • :;
* V ^^^^ - /«maf« JnalyHa qf Dry QxU.
^
i^i
100 per cent,
jiflture in sample of coal as received **
Analytit qf Ash aatd Rtfiue,
jO. Carbon per cent.
40. Earthy matter *•
Fv^ per Hmr.
41. Dry coal consumed per honr Ibt.
42. Combofltible consumed per hour •<
43. Dry coal per square foot of grate surftee per honr ... *•
44. Combustible per square foot of water>heating surface per
hour ««
Calorific Value i^Fvul,
45. Calorific value by oxygen calorimeter, per lb. of dry coal . B.T. IT.
4S. Calorific value by oxygen calorimeter, per lb. of combustible '*
47. Calorific value by analysis, per lb. of dry coalt **
48. Calorific value by analysis, per lb. of combustible .... **
Quality qf Steam.
40. Percentage of moisture in steam per cent.
BO. Number of degrees of superheating deg*
61. Quality of steam (dry steam = unity)
WaUar,
62. Total veight of water fed to boiler t . • • • 1^
63. Equivalent water fed to boiler from and at 212® • • • • **
64. Water actually evaporated, corrected for quality of steam "
66. Factor of evaporation! -' • 'j' J "
6d. Equivalent water evaporated into dry steam from and at
212°. (Item 54 X Item 66) •*
• TkU i» the total moitture in the coal a$ found by drying it artificially.
t See formula for calorific value under Article XVI . of Code,
t Qtrrectedfor ineguality qf water level and qf eteam preeture at begins
ffing and end of teat.
f Factor of evaporation = p^ ^-7' <« which H and h are respectively the
total heat in tteam of the average obterved preesuret and in water of the aver*
aye observed temperature qf the feed.
1390 • STEAM.
XXII. Repcrt tf ikt TViaJ.— The data and resnlto sboiild be reported la
the manner given in either one of the two following tables, omitanf JSam
where the teeta have not been made ae elaborately as prorided for in nA
tables. Additional lines may be added for data relating to the speeMs
object of the test. The extra lines ehonld be classified under the hcMlpgi
provided In the tables, sad nmnbered, ss per preceding line, with sob W*
ten, a, 6, etc. The Short Form of Report, Table No. S, is reeommeaM
for eommerdal teets and as a convenient form of abridging tbteloafvfacB
for pablication when saving of space is desirable.
Vable Ho. 1.
Data and ReautU ftf SvaporaHve Tet**
Arranged in aeeordanoe with the complete form advised by the B«Asr
Test €k>mmlttee of the American Society of Mediaalcal Engineeva.
Made by of boiler at ti
determine
Principal eondltionslgoveming the trial
Kind of f ael . . .
Kind of f nmaoe . .
State of the weather
1. Date of trial
2. Duration of trial
DimeiuUma and ProportUmM.
(A complete description of the boiler should be given on an annexed shestO
3. Grate surface . . . width . . . length . . . area . . sq. fL
4. Water>heatlng surface **
6. Superheating surface **
0. Batio of water-heating surface to grate surface
7. BaUo of minimum draft area to grate surface
Average Preuwrea.
8. Steam pressure by gauge lbs.
9. Force of draft between damper and boiler ....... ins. of «
10. Force of draft in furnace ** **
11. Force of draft or blast in ash-pit " *
Average ranpsrolttres.
12. Of external air dog.
13. Of flreroom **
14. Of steam **
15. Of feed-water entering heater **
16. Of feed-water entering economiser . **
17. Of feed-water entering boiler "
18. Of escaping gases from boiler "
19. Of escaping gases from economiser • **
90. Sise and condition
21. Weight of wood used in lighting Are us.
22. Weight of coal as fired* "
• Including equivalent qf wood uted in lighting the fire, not inehiSmg w-
humt coal withdrawn fhom f^imace at Hmeeqfcleamingaindat emdi^teH. <^
pound of loood is taken to be. equal to 0,4 pound qfeoal, or, in com ifiooIv
accuracy ie deHred^ at having a heat value equivalent to the eoaporatien ef
6 pounds qfwater/hm and at 212*^ per pound (6 x 9tf5.7 = ^,7M B.T,OJ*
RULES FOR CONDUCTING BOILER TESTS. 1391
SSw Peroantage of moisture in ooAl * ..... pero«&t.
9i. Total weQ^ht of dry ooal ooiiBiimed Itw.
95. Total ash and refuse lbs.
98. Total oombnstible consumed
97. Percentage of asb and refuse in dry ooal per cent
Proximate Analy$i9 qf Coal,
Of Coal. Of Combustible.
28. Pixed carbon per cent. per cent.
2». Volatile matter " **
90. Moisture "
SI. Ash "
100 per cent 100 per cent.
32. Sulphur, separately determined ** **
Ultimate AnalyHa qf Dry CoaU
33. Carbon (Q percent.
34. Hydrogen?!/) ••
36. Oxygen (O) "
38. Nitrogen (^) •«
a7. Sulphur i^S) **
100 per oent.
88. Moisture in sample of ooal as receiTed "
Analyeie of A»h and B^fiue.
39. Carbon percent
40. Earthy matter ••
Fuel per Hour'
41. Dry coal consumed per hour Ibg.
4SL Combustible consumed per hour <«
43. Dry ooal per square foot of grate surface per hour ... **
44. Combustible per square foot of water-heating surface per
hour *<
Cdlcrifio y<Uue<^Fuel.
46. Calorific ralue by oxygen calorimeter, per lb. of dry coal . B. T. IT.
46. Calorific ralue by oxygen calorimeter, per lb. of combustible "
47. Calorific ralue by analysis, per lb. of ary coalt **
48. Calorific ralue by analysis, per lb. of combustible .... **
Quality qf Steam.
49. Percentage of moisture in steam per cent.
80. Number of degrees of superheating deg.
51. Quality of steam (dry steam = unity)
Water,
6S. Total weight of water fed to boiler t lbs.
63. Equlralent water fed to boiler from and at 2X2«> • • • • "
64. Water actually eraporated, corrected for quality of steam «•
65. Factor of eraporatlonf ^' ' ' ^' ' "
66. Equlralent water eraporated into dry steam from and at
212°. (Item 54 X Item 65) "
• This i$ the total moisture in the coal as found by drying it artificially,
t See formula for calorific value under Article XVL of Code,
% Corrected for inequality of water level and qf steam pressure at begins
ging and end of test, a
f Foeinr of evaporation = ?^-7* »« which H and h are respectively the M
total heat in steam of the average observed pressure^ and in water qf the aver^ y
age observed temperature of the feed.
Ot.
1392 ST£AM.
Waierper Hour
67. Water evaporated per hour, corrected for quali^ of Bteam lbs.
58. Equiyalent evaporation per hour from and at 212° .... **
69. Equivalent evaporation per hour from and at 212° per
square foot of water-heating surface **
Horse-Power.
00. Horse-power developed. (34| lbs. of water evaporated per
hour into dry steam from and at 212P equals one horse-
power)* HJP.
61. Builders' rated horse-power **
62. Percentage of builders* rated horse-power developed . . .
Economk: BeauUt.
63. Water apparently evaporated per lb. of coal under actual
conditions. (Item 68 -^ Item 22)
64. Equivalent evaporation from and at 212*=* per lb. of coal
including moisture). (Item 66 -^ Item 22)
66. Equivalent evaporation from and at 212° per lb. of dry
coal. (Item 56 -r Item 24)
66. Equivalent evaporation from and at 212° per lb. of combae-
tible. (Item 56-7- Item 26)
(If the equivalent evaporation, Items 64, 65, and 66, is
not corrected for the quality of steam, the fact should
be stated.)
^ficieney.
67. Efflciencv of the boiler ; heat absorbed by the boiler per
lb. of combustible divided by the heat value of one lb.
of combustible f per
68. Efficiency of boiler, including the grate ; heat absorbed by
the boiler, per lb. of dry coal fired, divided by the heat
value of one lb. of dry coal %
Cbat qf BvaporatUm.
60. Cost of coal per ton of 2,240 lbs. delivered In boiler room • $
70. CkMtof fuel for evaporating 1,000 lbs. of water under ob-
served conditions $
71. Cost of fuel used for evaporating 1,000 lbs. of water from
and at 212° $
Smoke ObeervoHom.
72. Percentage of smoke as observed
73. Weight of soot per hour obtained from smoke meter . . .
74. Volume of soot obtained from smoke meter per hour . .
Tal»1« Ho. 9. ^
Data and BenUti of Evaporative Teet,
Arranged in accordance with the Short Form advised bv the Boiler Teit
Ck>raroittee of the American Society of Mechanical Engineers.
Made by on boiler, at ^
determine
• Held to be the equivalent of SO Iha. qf water per how evetporaied Ji^
100° Fahr. into dry tteam ctt 70 Ibe. gauge preamre.
t In all caeee where the itord " combustible " is used,it means the ooai with-
out moisture and a«A, but including all otTter eonstihients. ft is the same st
what is called in Europe " roal dry and free frxfm a«ft."
X The heat value of the coal is to be determined either by an oxygen catmim-
eter or by ceUcula'tion ./Wmi ultimate cMotysis. When both methods an
used the mean value is to be taken.
RULES FOR CONDUCTING BOILER TESTS. 1393
snrfaoe sq.ft.
Water-heating snrfaco *. **
Soperheatiiig surface **
Kind of f aef
Kind of f uniaoe
Total QuanHHe*.
1. I>ate of trial
2. I>aration of trial hours.
3. 'Weight of coal as fired lbs.
4. Peroentage of moisture in coal per cent.
6. Total weight of dry coal consumed lbs.
6. Total ash and refuse **
7. Percentage of ash and refuse in drv coal per cent.
8. Total weight of water fed to the boiler lbs.
9. Water actually evaporated, corrected for moisture or super-
heat in steam . "
Hourly Quantities.
10. I>ry coal consumed per hour lbs.
11. T>Tj coal per hour per square foot of grate surface ... **
12. Water fed per hour *•
13. Bquivalent water evaporated per hour from and at 212P
correctedfor quality of steam **
14. fquivalent water evaporated per square foot of water-
heating hour **
Average Pressurest Temperatures, etc.
15. Average boiler pressure lbs. per sq. in
16. Average temperature of feed-water deg.
17. Average temperature of escaping gases '*
18. ATerage force of draft between damper and boiler . . . ins. of watei
19. Percentage of moisture in steam, or number of degrees of
superheating
Hbrae-Potcer.
30. Horse>power developed (Item 13 -^ 34^) H.P.
21. Builders' rated horse-power "
22. Percentage of builders* rated horse-power per cent.
Economic Results.
23. Water apparently evaporated per pound of coal under
actual oonditions. (Item 8 4- Item 3) lbs.
24. Equivalent water actually evaporated from and at 212^^ per
pound of eoal as fired. (Item 9 -=- Item 3) **
26. Equivalent evaporation from and at 212° per pound of dry
ooal. (Item 9 -7- Item 5) '•
98. Equivalent evaporation from and at 212^' per pound of
combustible. [Item 9 -r (Item 6 — Item 6)]
(If Items 23. 24, and 25 are not corrected for quality of
steam, the fact should be stated.)
Efficiency,
27. Heating value of the eoal per pound ........ B.T.U.
28. Eflicienoy of boiler (based on combustible) **
29. Ei&ciency of boiler, including grate (basea on coal) ... **
Cost ftf Evaporation.
80. C^t of coal per ton of 2,240 pounds delivered in boiler-room 9
81. Cost of coal required for evaporation of 1,000 pounds of
water from and at 212° ^ S^
(
Tb«Ts Breae
.^ ^ ..— .r, tAklug the tflmpermtnrfl aI lU ontrAoo* to aad
1 from the condenier. Aootber i> bj oae of a Iwrrel CBlorimeUr. la
with oold wkMr, the added welt
■ umpl* of tha itaun la condaiued dinetl j Id a harrel htUj Ul
-" water, the added weight and leniHratare UUmo, and bj nae el
le qaalitf of (team ean be determlDed.
Both Che aboTS-named msthoiiB are now prsctloallj otiaoleta. aa thairplac*
by (hs Utroltling Ealorlmeter. used tor tloam la whld tk«
lot Biceed 3 per oeuC, and Ou> teparatiug calorlmaur, to
hai been taken by (ho tjinttling calorimeter, used for sl«am
moliton doe4 not eiceed " — — • —- ■ ••■ '- '
■(•am oontalnlDK a greater
In IM almplHt form (hi* loitmiaenC an be made up from pipe tttian,
(heonlyapeolalparia neceaaarj being the throttling Doule, wfaich la na«lT
made by boring ont a piece of brau rod that la the aame diameter aa a halH
Inohiteam pipe, leaving a ■mall bote In oneeDd.aaj A Inch diuietar. The
Inalde end of the imall nolo nhonld be tapered wltli Ineend of adrflleoaa
not to came eddiea; and the thennometer well, which U a *mall ^teee d
braa* pipe, plugoed at one end, and fltted Into a balf-lnch bm*hiii|(elt
Intopuce. l^ef olio ving cot hDVathelnatmmentaamade npfnuafliliaB,
Iba whole moat be oarefaU j ooTued wl(h aMne Don-oonditMor, la btbUa.
for mora aoonrate work tha toetnunanta dealgDad by Ototga H. turm,
H.E,, and Prof. R. C. Carpenter, are to be preferred, nufeaior Carpeatir^
Inatriunent la ihown la the following out, and dUTeia tram the primllln
Inatnunant praTlooalT deaorlbed onlj by the addlUon ol the aiiiii— til.
DETERMINATION OF MOISTURE. 1395
inM the pTtMore of (he iMun dboTs the etnioaptieTe In the
r tha lAlorlineter. With ■ free exit to the &lr the preeioie In th*
netar m>r be Uken M thkt at the ■Unoephere.
CmwpmmtKr'a TbrsttllBr CalorlBeatvr.
aeiie. BobMller * BndNibeig.)
Pio. g.
The perf ormted pipe for obtAlnln^ the eempla of ftleem to be teeted ahonld
nrefersM; be liuerled Id ■ Tertlesl pipe, ud ahould reech neurl; acroM
■NrscMoiu for Uec. — Ccintie«t u ehown Is Ibe precediDg cnte, IIU
en the Globe »»l»o for ua mlnutee or more In order lo bring the tempera-
tare of the Inelrament to full hest after which Dole the read&iEof the ther-
■umieter In theaeloilmeMr .and of Ibe altacbed mtuiometet or ofi barometer.
!%« #teaim gange ahould be carefully culebrated to aee that It Is cotreet.
A b>nnuet«r reading taken at the tune the ealorlmeter l> In nse. giTe*
greater aeonne; In norklns np tbe reeuJte than taking the average
atmoapberlo praeinr* u 11.0) ponndi. Preeanre In pounde mnj be deter-
mined from the mercury colamn of the barometer aad manoDteter by dlrld-
log tbe Inrbea rim by a.OS, or taking one ponnd for inch two Inchee of
mercnrr.
Followltig [g the rormTila for deterainlng the quality of iteam by nse of
tk» UtrotU&g calorineter.
n= total hsat In a pound of iteani at the privaare In the pipe.
h = total heat In a pound of ibiani at the preMure In (he calorimeter.
L = latent heat Id a ponnd of iteam at the preeanre In the pipe.
b = temperatare of boiling point at oalorlmetw prenwe (taken a*
2l4= with the " fltltnge^' Inatmment).
Mi = epealfle heat of superheated ateam.
X = quality of tbe steam.
V = percentage of molatnre In the ateam.
_ H~lt — M(t—b)
It * bl Mk«u M S19°, u it akn be villi bnt lU^t •rror, Ihrn
^^fl-lM».8-.«g(t-2ia) ^ ,^
FollowlnfuaUblM
.DrtermifUiiiaiu bg 1
EOWTOTSMKN
Per Cent of Molature In SI
nin
Am
■ nl
M
a
s
^
Theeuleet nutbodof tnkklDg the detcmlnUlDn* from the olmull
is bT u>e of the following diA^run, prepared bj ProfMiw CarpeaMr.
Find In Ihe Tertlcfti oolumn at the left the preaaure otMrrad b
e aboirn, and irhlab may ba IsMrpolMad '
>• ol (he Ilueg laid down.
re sDTTeipaiHltiii 1°
DETERMINATION OP MOISTURE.
1397
180
170
100
ISO
140
« 180
>
I 110
I
I 100
i ^
I 70
2
00
60
#0
SO
10
1
/
1
I
T\
/
/
1
t
171
1
1
/
1
1
/
1
1
/
1
1
/
1
/
d
¥
t
/
1
1
\
i
/
1
1
/
1
•
/
/
/
/
1
/
1
1
/
/
r
/
I
1
/
/
/
/
j
/
/
/
1
1
/
i
1
/
1
/
/
/
r
/
/
h.
/
/
<
1
1
/
1
1
'
/
/
1
/
i
/
^1
/
1
1
J
1
/
'
1
1
y
f
1
(
/
1
/
1
1
1
1
/
i
'
1
1
1
/
/
/
1
1
f
y
;
/
1
y
/
A
-A
/
1
1
1
i
/
/
1
1
/
t
1
/
/
1
/
/
/
1
1
t
/
t
1
i
^
i
1
1
f
J
^
1
1
I
'7
i
1
1
■
1
J
'
1
/
1
t
/
1
t
1
/
/
1 —
/
/
1
I
/
f
1
1
/
f
1
1
1
/
/
/
1
/
/
/
t
1
1
f/
/
/
/
/
1
t
/
~r~
1
1
1
1
t
1
(
4
/
/
<
/
1
1
1
/
7
1
1
K
M
/
1
t
V
i
/
/
1
1
/
1
f
1
i
/
/
:/
/
/
7
/
/
/
/
/
/
/
/
1
1
•N
K
V
7
/
/
f
t
1
/
/
/
/
/
/
/
i
J
f
/
/
/
1
//
1
1
_j _
/
/
f
/
f
/
/
/
/
1
^/
f
t
1
•
71
/
/
A
/
4
'
J
f
1
/
/
^
/
/
<^
i
/
t
J
/
/
I
t
/
/
>
i
/
/
f/
i
I
4
p
P
/
/
/
-*.-
V
L
f
1
/
f
/
/
/
/
i
/
/
1
o
V
i
J
/
r
/
r
*
/
<i
^y
/
/
.5
?^
r
/
/
4
/
f
/
/
/
/
/
/
t
J
f
/
/
/
/
i
^
^
V
/
>
/
/
i
/
>
J
/
(
/
1
0S
>/
/
/
/
/
>
/
'
/
/
/
J
Y
/
*
/
/
/
f
A
/
/
f
^
/
/
f
/
*
_>
/
/
/
•
^
/
/
•
•
/
/
y
.
/
•
/
^
y
^ci
ILC
JU
TIC
)N<:
;uF
VEJ
\
^'
^
y
y
y
^
•
f
^
y
/
FM
y
•
^
_ •
^
x'
^
iy
Th
IRC
TT
.iN^ a
kLC
RIti
ET
ER
,"
^
.^■^
^ ^
UNI
[OF
ATM
0«F'
1IRI
c pr
CM
IRE
^ **
.''
-^*
10
90
90 80 40 60 00 70 80
DCOneEt OF tUPCRHEAT IN THE CALORIMETER
OIAOIIMI OIVINQ RItULTt FROM THROTTUNQ CALORIMITIR WITHOUT OOMPUTATWIi
Pia.8.
1398 STEAM.
By putting a yalve in the discharge pipe of the calorimeter, being ean^il
that when open it offers no obetractiou to a free passage of the sfeww, ^
terminations may be made from temperatures without refereoee to a r"
Uble, and by using the following diagram by Professor Carpenter mx
lation is necessary.
a* Determine the boiling-point of the instrument by opening tasppkjiaii
discharge valves, and showering the instrument with cold watar li
produce moisture in the calorimeter, In which case the boOiiffiiMI
will be 212^ or thereabouts.
b. Determine temperature due to the boiler pressure by doeing the
charge-valve, leaving the supply-valve open, and obtain the full '
pressure in tne calorimeter.
e. Open the discharge-valve and let the thermometer settle to tbe i
ture due to the superheat.
Deduct the temperature of the boiling-point from this last tempeiatarels
obtain the degrees superheat. ^ ^ „ .m^
Suppose the boiling-point of the calorimeter to be 213°, the fouowi^ «»•
gram will give the result directlv from the temperatures.
To use the diagram when the boiling-point differs from ZIS®, add to tls
temperature of superheat the difference between the true boilinMobit ns
212®, if less than 2120 ; and subtract the difference if the true boOiiiiHWV
be greater than 212 ; use the result as before.
This instrument separates the moisture from the sample of
percentage is then found by the ordinary formula.
_±5^H°l^L5L«*»^^?^<i2?_ = per cent moiature.
total steam discharged as sample
■
One of the most convenient forms of this type of calorimeter is the m^i
designed by Professor Carpenter, and shown inrlg. 11. , u-j
The sample of steam is let into the instrument through tbe angle vawf
«. the moisture gathers in the inner chamber, its weight to PoundiM
hundredths being shown on the scale 12, and the dry steam fiows out thzom^ i
the small calibrated orifice 8. , ^ _j- , _^,__ i *- I
By Napier's law the flow of steam through an orifice Is proporoonsi w I
the absomte pressure, until the back pressure equals J» that of thesuiW '■
The gauge 9 at the right shows in the outer scale the flow of slsM '
through the orifice 8 in a period of 10 minutes' time. ,. w-
After attaching the instrument to the pipe from which sample is ttlw i
through a perforated pipe as with the throttUnsr or other Instrament, 8 i
must be thoroughly wrapped with hair, felt, or other tosulator. Steeali
then turned on ttirough the angle valve, and tfane enough aUoved toll*
oughly heat the instrument. _. ^^.^..^ * *_^
In taking an observation, first observe and record bea^t of ^^w^Jf
scale 12, then let the steam flow for 10 minutes, observlM the aTersgepoj;
tion of the pointer on the flow-gauge ; at the end of 10 mtoutos ote^
the height of water in gauge 12, and the difference between this and ■■
first observation will be the amount of moisture In the sample ; the per^
age of moisture will then be found as follows :
difference in scale 12 X 100
difference on scale 12 4- average for 10 minutes on the flow-gaoge
=% moisture.
For tests and data on " Calorimeters," see papers in Trans. A AMij*T
Messrs G. H. Barrus, A. A. Qoubert, and Professors Carpenter, Vmnm^
Jacobus, and Peabody.
DETERMINATION OF MOISTUBE.
1399
«
•
sso
a
MO
TEMPERATURE IN CALORIMETER
800 960 «I0 flW 890 aOO
810
880
880
841
"1
J
r
/
/
/
/
f
/
/
/
/
J
f
/
f
I
Z.
m
A».
/
/
r
7
/
'
/
/
r
/
/
/
7
/
/
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*/
/
r
/
/
i
/
/
r-
/
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7
/
. A
/
J
/
H
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v<
f
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f
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7
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7
J
r
J
f
7
7
y
r
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7
t,
7
. >
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7
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7
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7
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r
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7
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CU
RVE8 OF QU/
<LTY
1 *
/
/
FOR USE WITH
1
f
/
f
CARPEN
T
ER'S T
HP
lOTTLING CALC
»R
M
ETER 1
/
/
/
>
r
^
aiOfl0800S708809809008108808808a
TEMPERATURE IN CALORIMETER
CNAQRAM FOR OOMPUTINQ RESULTS WITH THROTTLING CALORIMETER.
FIG. 10.
•^
kn orUflA in m boiler or i
- ■ ■ - -litf
on« per cent from the coodiiioa ttf
wtuntlOD sltber In t))« dirvctioa al
wamsH or mparliBaUiif. Ooai*-
qnentl J If ft )M o( itaftu Bov tnH
ft boiler into tha fttnunAei
Ua loH of boftt oecDim
percepUt^ mol
ri
. Cftrpentcr'a Hew Erapor't-
'.«?"«:
be erea ■ grsTiall white ««r,
theiteam mftf be — nmwl ts t*
•o ne«rly drj that no patul4i
suable of meftaarias tbe >Bi«rt
of wftter theralD. 1} Um ]<• k*
«(rDiigl<r vbltei the ainaaal <■
Wftter msT be rooebly Indfed *
to about X par cent, bat immi
thl* B calorimeter only eu diMi-
mine the eiaot ajnonnt of KtM-
an. VllhftUttle ezpertcDca UT
one may determine by thl* mA-
od (he amdltjoiu of ateam vitUa
the ftboTe Ilmlta, A odbbb
braas pet cock may be iiaed ■* al
ortBoa, but It ahould. UptaatWa,
!» Bet into the Hteaia dnuD of tha
bollur and oeTer be placed laitka
away from the latter than toa
feet, and then only wbeu the ia-
tannedtMe reeervoir or p^ ii
well corarsd, for ft rery ahiiit
' dry steam thioogh '
In order to facilitate the t
latton of reducing the af toa
le of /aclari of emi^onMrm
I tb« total heat of iteam at
FACTORS OF EVAPORATION.
1401
Table ef Vttctont of
(Compiled by W. Wallace Christie.)
Oftoge
^ 1 ,«
Sressnre.
0
10
20
80
40
45
60 62
54
Xemp. of
Ibe.
lbs.
Ibt.
lbs.
lbs.
lbs.
lbs.
lbs.
IbB.
Feed.
9129 ¥.
1.0003
1.0088
1.0149
1.0197
1.0237
1.0264
1.0271
1.0277
14)288
909
1.0U36
1.0120
1.0180
1.0228
1.0268
1.0286
1.0302
1.0300
141315
ao6
1.0006
1.0161
1.0212
1.0200
1.0299
1.0317
1.0334
1.0340
14)346
208
1.0006
1.0183
1.0243
1.0291
1.0331
1.0340
1.0360
1.0372
1.0378
900
1.0129
1.0214
1.0276
1.0323
1.0362
1.0380
1.0997
1.0403
1.0400
197
1.0100
1.0M6
1.0906
1.0364
1.0394
1.0412
1.0428
1.0434
1.0441
194
1.0192
1.0277
1.0338
1.0386
1X)425
1.0443
1.0460
1.0466
1.0172
191
1.0223
14»06
IJOaOB
1.0417
1.0457
1.0474
1.0491
1.0497
1.0603
188
1.0266
1.084O
liMOO
1.0448
1.0488
1.0606
1.0622
1.0528
14)635
186
1.0286
14»71
1.0432
1.0480
1.0619
1.0537
1.0664
1.0600
1.0666
182
1.0317
14>40B
1.0463
1.0611
1.0651
1.0668
1.0685
1.0601
14)608
179
1.0348
1.0434
1.0406
1.0542
1.0682
1.0600
1.0616
1.0623
1.0628
176
1.0S80
1.0466
1.0628
1.0674
1.0613
1.0631
1.0648
1.0664
14)660
173
1.0411
1.0497
1.0657
1.0605
1.0645
1.0063
1.0079
1.0686
1.0092
170
1j0443
1.0628
1.0689
1.0636
tJOffie
1.0604
1.0710
imn
1.0728
167
1.0474
1.0660
1.0620
1.0068
1.0707
1.0726
1.0742
1.0748
1.0754
164
1.0606
1.0691
1.0661
1.0699
1.0739
1.0766
Lons
1.0780
1.0786
161
1.0637
1.0022
1.0682
1.0730
1.0770
1.0788
1.0804
1.0811
1.0817
158
1.0668
ijoeea
1.0714
1.0702
1.0H01
1.0819
1.0836
2.0842
1.0648
1B6
1.0690
1.0684
1.0746
1X)793
1.0833
1.0650
1.0867
1X>873
1.0880
152
1.0631
1J0119
1.0776
1.0824
1.0864
1.0682
1.0898
1X)905
1.0011
149
1.0662
ijon*!
1.0606
1.0865
1.0805
1.0913
1.0030
1.0036
14)042
146
ijoms
1.0778
1.0839
1.0887
1.0026
1.0044
1.0061
14)067
14)973
149
1.0724
14)810
1.0870
1X018
1.0068
1.0076
1.0002
1j0098
1.1006
140
1.0766
1.0841
1.0901
1.0040
1.0089
1.1007
1.1023
1.1030
1.1036
157
1U)787
1.0872
1.0033
1.0080
1.1020
1.1038
1.1066
1.1061
1.10G7
194
1.0818
1.0008
1.0064
1.1012
1.1051
1.1069
1.1086
1.1092
1.1008
131
1.0849
1.0034
1.0006
1.1043
1.1083
1.1100
1.1117
1.11SS3
1.1130
128
ijoesi
1.0966
1.1026
1.1074
1.1114
1.1132
1.1148
1.1166
1.1161
126
1.0012
1.0097
1.1067
1.1106
1.1145
1.1163
1.1179
1.1186
1.1192
123
1.0043
1.1028
1.1069
1.1136
1.1176
1.1194
1.1211
1.1217
1.1223
119
1.0074
1.1060
1.1120
1.1168
1.1207
1.1225
1.1242
1.1248
1.1264
116
1.1005
1.1090
1.1161
1.1190
1.1230
1.1256
1.1273
1.1279
1.1286
113
1.1036
1.1122
1.1182
1.1230
1.1270
1.1288
1.1304
1.1310
1.1317
110
1.1068
1.1163
1.1213
1.1261
1.1301
1.1319
1.1335
1.1342
1.1348
107
1.1099
1.1184
1.1246
1.1292
1.1332
1.1360
1.1366
1.1373
1.1379
104
1.1130
1.1215
1.1276
1.1323
1.1^63
1.1381
1.1308
1.1404
.1.1410
101
1.1161
1.1246
1.1307
1.1365
1.1394
1.1412
1.1429
1.1436
1.1441
98
1.1192
1.1277
1.1338
1.1386
1.1426
1.1443
1.1460
1.1466
1.1473
96
1.1223
1.1309
1.1369
1.1417
1.1457
1.1475
1.1491
1.1497
1.1604
92
1.1256
1.1340
1.1400
1.1448
1.1488
1.1606
1.1622
1.1529
1.1635
80
1.1286
1.1371
1.1431
1.1479
1.1519
1.1637
1.1663
1.1660
1.1566
86
1.1317
1.1402
1.1463
1.1510
1.1660
1.1568
1.1684
1.1691
1.1607
83
1.1348
1.1433
1.1404
1.1641
1.1681
1.1609
1.1616
1.1622
1.1628
80
1.1379
1.1464
1.1625
1.1673
1.1612
1.1630
1.1647
1.1663
1.1660
77
1.1410
1.1405
1.1666
1.1604
1.1644
1.1661
1.1678
1.1684
1.1690
74
1.1441
1.1626
1.1587
1.1635
1.1676
1.1692
1.1700
1.1716
1.1722
71
1.1472
1.1668
1.1618
1.1666
1.1706
1.1723
1.1740
1.1746
1.1763
68
1.1604
1.1689
1.1640
1.1697
1.1737
1.1765
1.1771
1.1778
1.1784
fl6
1.1636
1.1620
1.1680
1.1728
1.1768
1.1786
1.1802
1.1800
1.1815
62
1.1666
1.1661
1.1711
1.1769
1.1799
1.1817
1.1833
1.1840
1.1846
60
1.1607
1.1682
1.1743
1.1790
1.1830
1.1848
1.1864
1.1871
1.1877
66
1.1628
1.1713
1.1774
1.1821
1.1861
1.1879
1.1896
1.1902
1.1908
63
1.1669
1.1744
1.1806
1.1862
1.1892
1.1910
1.1927
1.1933
1.1939
60
1.1690
1.1775
1.1836
1.1884
1.1923
1.1941
1.1958
1.1964
1.1970
47
1.1721
1.1806
1.1867
1.1916
1.1964
1.1972
1.1989
1.1996
1.2001
44
1.1762
1.1837
1.1898
1.1946
1.1986
1.2003
1.2020
1.2026
1.2032
41
1.1783
1.1868
1.1929
1.1977
1.2017
1.2094
1.2061
1.2067
1.2064
38
1.1814
1.1900
1.1960
1.2008
1.2018
1.2065
1.2082
1.2088
1.2005
36
1.1846
1.1031
1.1991
1.2089
1.2079
1.2006
1.2113
1.2119
1.2126
32
1.1876
1.1962
1.2022
1.2070
1.2110
1.2128
1.2144
1.2151
1.2167
J
1
rACTORS OF EVAPORATION.
1403
Table of
9m€t9vm If :
BrapomtlOB.
teuge
1
'entire.
100
106
116
125
135
146
166
165
185
■np. of
Lbs.
Lbs.
Lbs.
Lbs.
Lbs.
Lbs.
Lbs.
Lbs.
Lbs.
reed.
«20F,
1.0367
1.0407
1.0127
1.0445
1.0462
1.0478
1.0493
1.0609
1.0636
200
1.0129
1.0438
1.0158
1.0476
1.0483
1.0600
1.0624
1.0640
1.0567
906
1.0460
1.0470
1.0489
1.0610
1.0527
1.0643
1.0668
1.0674
1.0601
«»
li>492
1.0602
ixxm
1.0640
10667
1.0673
1.0688
1.0604
1.0631
900
1.0623
1.0633
1.0662
1.0671
1.0688
1.0604
1.0610
1.0H:15
1.0662
197
1.0666
1.0666
1.0684
1.0602
1.0619
1.0635
1.0660
1.0666
1.0603
IM
1.0686
1.0606
1.0616
1.0635
1.0662
1.0668
1.0683
1.0609
14)726
191
1.0617
1.0627
1.0647
1.0666
1.0682
1.0698
1.0713
1.0729
1.0766
188
1M§B
1.0669
1.0678
1.0696
1.0728
1.0713
1U)720
14)744
1.0760
1.0787
186
1.0680
1.06B0
1.0709
1X>746
1U)761
1.0776
1.0792
1.0819
182
1.0712
1.0722
1.0741
1.0760
1.0T76
1.0792
1-0807
1.0823
1.0860
179
1.0743
1.0768
1.9772
1-0790
1.0807
1.0823
1.0838
1.0864
1.0881
176
1.0774
1.0784
1.0803
1.0822
1.0839
1.0665
14)870
1.0686
14)913
173
1.0606
1.0616
1.6836
1.0658
1.0870
1.0886
1.0001
1.0017
1.0944
170
1.0837
1.0647
ijosee
1.0884
1.0901
1.0917
1-0938
1.0048
1.0916
197
1.0868
1.0878
1.0897
1.0916
1.0033
1.0949
14)964
1.0980
1.1007
164
1.0900
1.0010
1.0929
1.0946
1.0963
1.0979
14IB94
1.1010
1.1087
161
1.0031
1.0041
1.0960
1.0979
1.0996
1.1012
1.1027
1.10»3
1.1070
158
1.0062
1.0972
1U)991
1.1010
1.1027
1.104B
1068
1.1074
1.1101
vm
1.0993
1.1003
1.1023
1.1041
1.1068
1.10r74
1069
1.1106
1.1132
ISQ
1.1006
1.1035
1.1064
1.1073
1.1090
1.1107
1122
1.1138
1.1166
140
1.1056
1.1066
1.1086
1.1103
1.1120
1.1136
1161
1.1167
1.1194
146
1.1087
1.1007
1.1116
1.1135
1.1152
1.1168
1183
1.1199
1.1226
143
1.1118
1.1129
1.1148
1.1166
1.1183
1.1199
1214
1.1230
1.1267
140
1.1160
1.1160
1.1179
1.1197
1.1214
1.1230
1246
1.1261
1.1288
137
1.1181
1.1191
1.1210
1.1228
1.1246
1.1282
1277
1.1293
1.1320
194
1.1212
1.1222
1.1241
1.1200
1.1277
1.1293
1306
1.1324
1.1361
131
1.1243
1.1268
1.1273
1.1291
1.1308
1.1324
1339
1.1366
1.1382
12B
1.1275
1.1286
1.1304
1.1322
1,1339
1.1366
1370
1.1386
1.1413
126
1.1306
1.1316
1.1335
1.1363
1.1370
1.1386
1401
1.1417
1.1444
132
11337
1.1347
1.1306
1.1384
1.1401
1.1417
1438
1.1448
1.1476
119
1.1368
1.1378
1.1397
1.1416
1.1432
1.1449
1464
1.1480
1.1607
116
1.1399
1.1409
1.1429
1.1447
1.1464
1.1480
1486
1.1511
1.1538
113
1.1431
1.1441
1.1460
1.1478
1.1496
1.1511
1626
1.1542
1.1569
110
1.1462
1.1472
1.1491
1.1609
1.1616
1.1642
1557
1.1673
1.1000
107
1.1483
1.1608
1.1522
1.1540
1.1667
1.1573
1688
1.1604
1.1631
104
uwa
1.1634
1.1553
1.1571
1.1588
1.1606
1619
1.1635
1.1662
101
1.1655
L1666
1.1684
1.1602
1.162D
1.1636
1662
1.1668
1.1696
98
1.1586
1.1696
1.1616
1.1634
1.1651
1.1667
1683
1.1699
1.1726
86
1.1618
1.1628
1.1647
1.1666
1.1682
1.1608
1713
1.1729
1.1756
92
1.1649
1.1680
1.1678
1.1696
1.1713
1.1729
1744
1.1760
1.1787
89
1.1680
1.16D0
1.1709
1.1727
1.1744
1.1760
1775
1.1791
1.1818
86
1.1711
1.1721
1.1740
1.1768
1.1775
1.1791
1806
1.1822
1.1849
83
1.1742
1.1752
1.1771
1.1789
1.1806
1.1823
1837
1.1853
1.1880
80
1.1773
1.1783
1.1802
1.1820
1.1837
1.1864
1869
1.1885
1.1912
T7
1.1804
1.1814
1.1834
1.1862
1.1860
1.1885
1900
1.1916
1.1943
74
1.1885
1.1846
1.1866
1.1888
1.1900
1.1916
1932
1.1948
1.1976
71
1.1867
1.18T7
1.1886
1.1914
1.1931
1.1947
1961
1.1977
1.2004
68
1.1896
1.1908
1.1927
1.1946
1.1962
1.1978
1993
1.2009
1.2036
66
1.1929
1.1939
1.1968
1.1976
1.1993
1.2009
.2024
1.2040
1.2067
62
1.1960
1.1970
1.1989
1.2007
1.2024
1.2040
2065
1.2071
1.2008
m
1.1991
1.20O1
1.2020
1.2038-
1.2065
1.2071
.2086
1.2102
1.2129
66
1.2022
1.2032
1.2061
1.2069
1.2066
1.2102
2117
1.2133
1.2160
63
1.2063
1.2063
1.2083
1.2100
1.2117
1.2134
2148
1.2164
1.2191
BO
1.2084
1.2094
1.2118
1.2131
1.2148
1.2165
2180
1.2196
1.2223
47
1.2116
1.2126
1.2144
1.2163
1.2180
1.2196
2211
1.2227
1.2264
44
1.2146
1.2156
1.2176
1.2194
1.2211
1.2227
2242
1.2268
1.2286
41
1.2177
1.2187
1.2207
1.2225
1.2242
1.2268
22^3
1.2289
1.2316
38
1.2206
1.2219
12238
1.2266
1.2273
1.2289
2304
1.2320
1.2347
36
1.2240
1.2260
12200
12287
1.2304
1.2320
2335
1.2361
1.2376
32
1.2271
1.2281
1.2300
1.2318
1.2335
1.2361
2366
1.2382
1.2409
^
&TirSATBB STB AH
tits V-E.i
(W.W.Chni
k
.a|
1'
la
:u2
a
30
38
'^&'"3*"f^''
™-
1
<
6
li
1092,7
ii;i
s
ii
Edktin
„^
(
Co. Ft.
if
^Wl»
79380
B8380
3387
ii
1
W.flS
.m
40
8
!
El
i09e:o2
154330
E
in
ii
i
1
si
1078:47
io9s:*7
s
1874
isae
isie
\
ii
1
1
i
1076.08
1070:93
1099.08
si
87500
71330
i
ii
aa.ia
1
i
i
38
ill
1102:1*
seoao
1009
944,7
885,0
J
3B.03
28. M
.385
'.Mi
11
40
11
103.90
10B:70
1
829.5
685:2
i
II
.KB
:609
80
SZ
iii
1054:22
1100.40
iiii
i
643.8
!i
28.90
28:32
.738
.785
88
1
1052.83
ill
5USg
20020
SOS. 7
"1
28.22
27:89
.:i
i
1047.27
EI
iiil
24M0
23140
20«»
334.5
j
27,76
27:3*
11
104
71
ill
iiii
1116.65
19500
16620
i:?
367.5
1
27. 1»
11
ii
ill
80
86
ill
!li',:S
1G640
237.3
216.5
90S
iS:S
!:S
132
^
1030.55
1118.00
1119.21
i;^
204.4
Ml
ootia
tOPAliXlMS 09 BAXVMAXXO BVtllkM.. — Continued.
^
17
91
7.16
i5.67
5.95
5.31
8.33
7.40
6.45
5.46
4.44
3.38
2.28
1.15
0.00
If
HI
1.879
1.984
2.096
2.213
2.335
2.461
2.594
2.732
2.876
3.029
3.188
3.353
3.526
3.707
3.896
4.090
4.295
4.607
4.729
4.960
6.200
5.451
5.711
5.981
6.262
6.555
6.857
7.172
7.500
7.841
8.194
8.558
8.936
9.330
9.738
10.16
10.59
11.05
11.52
12.00
12.50
13.02
13.56
14.12
14.70
124
126
128
130
132
134
136
138
140
142
144
146
148
150
152
154
156
158
160
162
164
166
168
170
172
174
176
178
180
182
184
186
188
190
192
194
196
198
200
202
204
206
208
210
212
Heat Units in one Found
above 32* F.
3
92
94
96
98
100
102
104
106
108.1
110.1
112.1
114.1
116.1
118.1
120.1
122.1
124.1
126.1
128.1
130.1
182.2
134.2
136.2
138.2
140.2
142.2
144.2
146.2
148.2
150.3
152.3
154.3
156.3
158.3
160.3
162.3
164.3
166.4
168.4
170.4
172.4
174.4
176.4
178.5
180.5
1027.76
1026.37
1024.97
1023.58
1022.18
1020.79
1019.39
1018.00
1016.60
1015.20
1013.81
1012.41
1011.01
1009.61
1008.22
1006.82
1005.42
1004.02
1002.62
1001.22
998.42
997.02
995.62
994.22
992.82
991.42
990.02
983.62
987.21
985.81
984.41
983.00
981.60
980.20
978.79
977.39
975.98
974.58
973.17
971.76
970.36
968.95
967.54
966.13
119.82
120.43
121.04
121.65
122.26
122.87
123.48
124.09
124.70
125.31
125.92
126.53
127.14
127.75
128.36
128.97
129.85
130.19
130.80
131.41
132.02
132.63
133.24
133.85
134.46
135.07
135.68
136.29
136.90
137.51
138.12
138.73
139.34
139.95
140.56
141.17
141.78
142.39
143.00
143.61
144.22
144.83
145.44
146.05
1146.66
Volume.
Rela-
tive.
Cu.Ft.
inlCu.
Ft. of
Water.
11370
10800
10265
9760
9276
8826
8401
7991
7613
7258
6920
6595
6290
6004
5734
5477
5232
5000
4779
4569
4368
4177
3996
3826
3664
3510
3365
3226
3093
2966
2846
2733
2624
2519
2420
2325
2234
2147
2064
1985
1916
1844
1775
1708
1644
Specific
Cu.Ft.
in one
Lb. of
Steam.
184.1
174.8
166.1
157.8
160.1
142.8
135.8
129.3
123.2
117.3
111.8
106.6
101.7
97.03
92.61
88.43
84.47
80.70
77.14
73.77
70.56
67.51
64.62
61.85
59.25
56.76
54.40
52.14
60.01
47.97
46.06
44.17
42.41
40.73
39.13
37.59
36.13
34.73
33.40
32.13
30.92
29.76
28.63
27.57
-el
^
i
.005432
5720
6020
6336
6664
7005
7361
7782
8120
8522
8942
9379
.009833
.01031
.01080
.01131
.01184
.01239
.01296
.01356
.01417
.01481
.01548
.01617
.01688
.01762
.01838
.01918
.02000
.02085
.02172
.02264
.02358
.02455
.02556
.02660
.02768
.02879
.02994
.03112
.03235
.03361
.03493
.03628
(
26.60 .03760
1405
1406
SIC AM.
(Compiled by W. W. Christie.)
snAi
K.
Pounds per
Square Incb.
E-i
Heat Units in one
Pound above 32° F.
Yolanie.
1 HI
•
§
1*
•
«
1^
<
♦-'St' •
w&xi
Rela-
tlTe
Spedflc
Cu. Ft.
in 1 Cu.
Ft. of
Water.
Cn. Ft.
in one
L.b. of
Ste^m.
1
2
3
4
102.
126.2
141.6
163.0
70.1
94.4
100.8
121.4
1042.9
1096.0
1016.2
1007.2
1113.0
1120.4
1126.1
1128.6
20623
16730
7325
5688
390.4
171.9
117.3
89^
iHBI
JOOS
Ma
5
6
7
8
162.3
170.1
176.9
182.9
130.7
13RJS
145.4
151.4
1000.7
996.2
990.4
986.2
1131.4
1133.8
1135.8
1137.7
4530
3816
3302
2912
73^
61.14
52.89
46.66
MS
JHm
9
10
11
12
188.3
193.2
197.7
201.9
166.9
161.9
166.6
170.7
962.4
978.9
976.7
972.8
1139.3
1140.8
1142.2
1148.5
2607
2361
2160
1390
41.77
37.®
34J»
31.87
jQsai
jam
J9k
1^
13
14
16
16
206.8
209 J>
213.0
216.3
174.7
178.4
181.9
186.2
970.0
967.4
964.9
962.6
1144.7
1146.8
1146.9
1147.9
1845
1721
1614
1519
S9JS6
94.33
.on
jam
JSBS
Ma
2.3
8.3
4.3
5.3
17
18
19
20
219.4
222.3
225.2
227.9
188.4
191.4
194.2
197.0
960.4
958.3
966.3
064.4
1148.8
1149.7
1160.6
1161.4
1434
1369
1292
1231
22i»
21.72
20.70
19.73
MB
jm
JSK
6.3
7.3
8.3
9.3
21
22
23
24
230iS
233.0
236.4
237.7
199.6
202.2
204.6
207.0
062.5
960.8
949.0
947.4
1162.2
1163.0
1163.7
1154.4
1176
1126
1080
1088
18^
18.04
17.30
16.63
MSL
.(EM
jsm
10.3
11.3
12^
13.3
25
26
27
28
240.0
242.1
»i4.2
246.3
209.3
211 JS
213.6
216.7
946.8
944.2
942.7
941.3
11RR.1
1166.8
1156.4
1157X)
998.4
962.3
928.8
897.6
16.00
16.42
14.88
14.38
sm
jsm
am
14.3
16.3
16.3
17.3
29
30
31
32
248.3
250.2
262.1
263.9
217.7
219.7
221.6
223.6
939.9
938.9
937.1
936.9
1167.6
1168.2
1158.8
1150.S
868J>
841.3
816.8
791.8
13^1
13.48
13J)7
12^
JBB
jam
jam
jsm
18.3
19.3
20.3
21.3
83
34
36
36
256.7
257.4
259.1
260.8
225.3
227.1
228.8
230J»
934.6
933.3
932.1
931.0
11S9.9
1160.4
1100.9
1161.5
769.2
748.0
727.9
708.8
12.33
11.98
11.66
11.37
jam
jsa
jn
jom
22.3
233
24.3
25.3
87
38
39
40
262.4
2G4.0
265.6
267.1
232.1
2334)
236.3
236.9
929.8
928.6
927.6
926.4
1161.9
1162.4
1162.9
1163.4
090^
673.7
657.5
642.0
11.07
10.79
10Ji3
10.28
jm
JOBS
.€90
jam
26.3
27.3
41
42
268.6
270.0
238.4
239.9
925.4
924.3
1163.8
1161.3
627.3
613.3
10X6
9.82S
J08S5
.KKU
^
PROPERTIES OF SATURATED STEAM.
1407
ov mAxmmAXMMB m'wmjkjm—ameiftued.
Poondsper
Square Iiich.
1^
Heat Units in one
Pound above 32<' F.
Volume.
«
rf
•
II
si
S ® s 0
llH
<
Rela-
tive
Speoiflc
<
Cn. Ft.
inlCu.
Ft. of
Water.
Cu.Ft.
in one
Lb. of
Steam.
»3
43
44
46
46
3713
272.9
274.3
275.6
.241.4
2423
344.2
246.6
9283
9223
9213
9203
1164.7
1166.1
11663
1166.0
6903
6873
674.7
663.0
9.609
9.408
9.207
9318
.1041
.1068
.1066
.1109
823
8*3
363
47
68
40
60
2763
278.2
2793
2803
247.0
248.3
249.6
2603
919.4
918.4
9173
916.6
1188.4
1166.8
1167.2
11673
651.7
M03
6303
6203
8.888
8.498
8388
.im
.1154
.1177
.1190
3«3
873
883
393
61
68
63
64
282.1
283.3
2843
286.7
262.2
2633
264.7
2663
915.7
9143
913.9
913.1
11673
11683
1168.7
1169.0
510.9
601.7
482.8
484.2
8.186
8.087
7.894
7.756
.1222
.1244
.1267
.1289
403
413
433
433
66
66
67
68
288.9
288^
289.1
2903
267.1
258.3
2693
200.6
912.2
911.4
9103
9003
1169.4
1160.7
1170.1
1170.4
4753
467.9
460.2
462.7
7.eM
7.496
7372
7.252
.1318
.1384
.1367
.1379
443
453
403
473
60
60
61
62
291.4
2923
293.6
294.6
261.7
262.9
264.0
266.1
9093
908.2
907.4
906.7
1170.8
1171.1
1171.4
1171.8
4453
4383
431.7
4263
7.136
7.024
6316
6311
.1401
.1424
.1446
.1463
483
493
603
513
63
64
66
66
296.7
296.7
297.7
298.7
266.1
267.2
2683
2693
9053
906.2
904.4
903.7
1172.1
1172.4
1172.7
U73.0
4183
412.6
4063
4003
6.700
6.610
6315
6.422
.1491
.1513
.1535
.1657
S83
883
643
663
67
68
69
70
299.7
800.7
801.7
802.7
2703
2713
272.3
273.3
9033
902.3
9013
9003
11733
1173.6
1173.9
1174.2
3963
389.8
3843
8793
6.332
6.244
6.166
6.076
.1079
.1603
.1624
.1646
663
873
683
603
71
72
78
74
803.6
804.6
3063
306^
2743
2753
276.2
277.2
900.2
8093
898.8
898.1
11743
1174.8
1175.1
1176.4
8743
360.4
364.6
360.0
5.906
6317
5.841
5.767
.1668
.1690
.1712
.1734
G03
613
63.3
6S.3
75
76
77
78
8073
808.2
309.1
810.0
278.1
279.0
280.0
2803
8973
8963
896.2
8863
1176.6
11763
1176.2
11763
3R63
361.1
8463
342.6
5.694
5.624
6365
5.488
.1756
.1778
.1800
.1822
M.8
663
663 .
673 ^
79
80
81
82
8103
3113
312.6
3133
281.8
282.7
2833
284.4
8943
894.3
883.7
893.1
1176.7
1177.0
1177.3
11773
.3383
3343
330.6
3263
5.422
6358
6.296
5335
.1844
.1866
.1888
.1910
663
663
83
84
8143
318.1
2863
286.1
892.4
801.8
11773
1178.0
323.1
3193
5.176
5.118
.1932
.1964
1408
STEAM.
PKOPSM
nOM i
DV SAWMATKD
0TMi
!«-<
PoondB per
Square Inch.
H
Heat Units in one
Pounds abore SOP F.
Yolnmo.
J986
•
.^i
•
m
+.,-3b
Bela-
Ure
SpeeUk
1^
H
<
II 0 V S
Cn. Ft.
inlGa.
Ft. of
Water.
Cu.Ft
n ILb.
of
Steam.
f
6J061
6J006
4J61
4.806
70.3
71.3
72.3
78.3
86
86
87
88
316.0
316.8
317.6
318.4
287.0
287.8
288.7
289 J(
891.2
880.6
890.1
889.6
1178.3
1178.6
1178.8
1179.0
316.9
312i»
309.1
305.8
74.3
75.3
76.3
77.3
89
90
91
92
319.2
320.0
320.8
321.6
280.8
291.1
291.9
292.7
888.8
887.8
887.2
1179.3
1179.6
1179.8
1180.0
802.6
299.4
296.3
298^
4JB46
4.796
4.746
4.e07
jam
.2139
78.3
79.3
80.3
81.3
93
94
96
98
322.3
323.1
323.8
324.6
293.6
294.3
295.1
206.9
886.6
886.1
885.6
885.0
1180.2
1180.4
1180.7
1180.9
290.2
287.8
284J»
281.7
4.660
4.608
4.557
4^13
.2151
.2ns
.201
jesii
82.3
83.3
84.3
86.3
97
98
90
100
325.3
326.1
326.8
327 JS
296.6
297.4
296.1
298.0
884 j;
883.9
883.4
882.9
1181.1
1181.4
1181.6
1181.6
279.0
276.3
273.7
271.1
4.469
4.^6
4.384
4.342
jam
86.3
87.3
88.3
89.3
101
102
103
104
328.2
329.0
329.7
330.4
299.6
300.4
301.1
301.8
882.3
881.8
8813
880.8
1182.0
1182.2
1182JS
1182.7
268JS
206.0
263.6
261.2
4.308
4.2SS
4.166
JiMf
JS9B
.S90
90.3
91.3
92.3
93.3
106
106
107
108
331.1
331.8
332.4
333.1
302JS
303.3
304.0
304.7
880.3
879.8
879.3
878.8
1182.9
1183.1
1183.3
1183 J(
258.9
266.6
254.3
262.1
4.147
4.110
4.074
4.068
JXSl
.2138
.9I7S
94.8
95.3
96.3
97.3
100
110
111
112
338.8
334J:^
336.1
336.8
306.4
306.1
306.8
307.4
878.3
877.8
877.8
876.9
1183.7
1183.9
1184.1
1184.3
2l8il
247.8
2«5.7
243.6
4j0a3
3^69
3JI36
3JM«
.906
J5»
J5I1
jsa
98.3
99.3
100.3
1C1.3
113
114
116
116
336.6
337.1
33'/.8
338.4
308.1
308.8
300.6
310.1
876.4
875.9
876.4
876.0
1184.5
1184.7
1184.9
1186.1
241.6
239.6
237.6
236.7
3.870
3.838
3.806
3.776
jtm
102.3
103.3
101.3
106.3
117
118
119
120
339.1
339.7
340.3
340.9
310.8
311.4
312.1
312.7
874.5
874.0
873.6
873.1
1186.3
1186.6
1186.7
1186.9
2S3.8
231.9
230.1
228.3
3.745
3.715
3U«6
3.666
jM
106.3
107.3
108.3
109.3
121
122
123
124
341.6
342.2
342.8
343.4
313.4
314.0
314.7
316.3
8T2.7
872.6
871.8
8n.3
1186.1
1186.3
1186JS
1186.6
226^
224.7
223.0
221.3
3.628
3.600 i
3.616
3!S
.28S1
110.3
111.3
325
126
344.0
344.6
316.9
316.6
870.9
870.4
1186.8
1187.0
219.6
218.0
3j518
3.492
jm
PROPERTIES OP SATURATED STEAM.
1409
LOPBSVIS0 09 0 Asms Ann BT^Am-^CoHHnmsd.
Poimdsper
Square lAcb.
m
Is
Heat XTnlts in one
Pound above 929 F.
Volame.
il
<
Relar
tive
Cu.Ft.
inl Ctt
Ft. of
Water.
Specific
JOOQ
Cn. Ft.
inl Lb.
of
Steam.
1123
1133
1143
1163
127
128
129
130
346.2
3463
346.4
347.0
317.2
317.8
318.4
3193
870.0
889.6
860.1
868.7
1187.2
1187.4
1187.6
1187.8
816.4
2143
2133
211.6
3.466
3.440
3.415
3380
.2886
3907
3988
3860
1163
1173
1183
1193
131
132
133
134
347.6
348.2
348.8
348.8
319.6
320.2
320.8
321.4
8683
8673
867.4
867.0
11873
1188.1
11883
11883
210.1
206.6
207.1
206.7
3366
3.342
3318
3.206
3971
.2809
.3014
3085
1203
1213
122.3
1233
135
136
137
138
340.0
3603
361.0
361.7
322.0
322.6
823.2
8233
806.6
366.2
865.7
8053
1188.6
11883
1189.0
1180.1
204.2
202.8
201.4
200.0
3.272
3.240
3.227
3304
3057
3078
3000
3121
1243
1283
1263
1273
130
140
141
142
3R2.2
362.7
3R33
3633
3243
324.9
3263
326.1
864.0
8643
864.1
863.7
11803
11803
1189.7
11803
198.7
1973
196.0
194.7
3.182
3.161
3.140
3.110
3148
3168
.8185
3206
128.3
1293
1303
1313
148
144
146
146
354.4
3643
3663
366.0
326.8
327.2
327.8
328.3
8633
8623
8623
862.1
1190.0
1190.2
11903
1190.4
198.4
192.2
1903
189.7
3309
3.078
3.068
3.038
3227
3248
3270
3201
1323
1333
1343
1383
147
148
140
160
3563
367.1
367.6
368.1
328.9
329.4
330.0
3303
861.7
861.4
861.0
8603
1190.6
1190.8
1191.0
1191.1
18R.6
1873
186.1
1843
3.019
3300
2.981
2.96B
3318
3884
3385
3876
1363
1373
1383
138.3
161
162
168
164
8583
360.2
350.7
360.2
331.1
331.6
332.2
332.7
860.2
860.8
860.4
860.1
11913
1191.4
1191.6
1191.8
183.7
182.6
1813
180.4
^ 2.943
2.926
2306
2.880
3388
3419
.3439
3460
1403
1413
1433
143.3
166
166
167
168
300.7
361.2
361.7
362.2
333.2
333.7
3343
3343
868.7
8583
8573
8673
11913
1192.1
1192.2
1192.4
179.2
178.1
1773
176.0
2.870
2.853
2.835
2.819
3606
3626
3647
1443
1403
1463
1473
180
160
161
162
362.7
363.2
363.7
364.2
3363
3353
336.3
336.9
867.2
8563
866.5
866.1
11923
1192.7
11923
1193.0
174.9
1733
1723
1713
2302
2.786
2.770
2.754
3568
3588
.3610
3681
146.3
1483
1M>3
1613
163
164
165
166
364.7
365.2
365.7
366.2
337.4
3373
338.4
3383
856.7
856.4
855.0
854.7
1193.1
11933
11933
1193.6
1713
1703
1693
168.1
2.739
2.728
2.707
2.603
3680
3672
3603
3714
1623
US83
167
168
366.7
387.1
339.4
3303
854.3
853.9
1193.7
11933
167.1
166.2
2.677
2.662
3786
3766
i
r
1410
BTEAM.
VrMMM or SATITSAVn^ SVBAM-
Pounds per
Square Inch.
H
Heat Unita in One
Pound above 309 F.
•
«.8
•
If
ll
<
^1
•<
164.3
165.3
166.3
1673
169
170
m
17S
307.6
368.1
368.6
369.1
340.4
340.9
341.4
3413
863.6
8633
8R23
862.6
11043
1104.2
11943
11943
158.3
169.3
160.3
161.3
173
174
176
176
369.6
370.0
370^
370.0
842.4
3423
3433
343.8
8623
8613
8613
851.3
1194.6
1194.8
11943
1196.0
ie2JI
1634^
164.3
166.3
177
178
179
180
371.4
871.9
372.3
372.8
3443
3443
3463
346.7
8R03
8603
8603
8483
1106.2
11953
11953
1196.6
166.3
167.3
168.3
169.3
181
182
183
184
373.2
373.7
374.1
874.6
3463
346.7
347.1
3473
8403
848.8
8483
8483
1195w7
11953
1196.0
1196.2
170.3
171.3
172.3
1733
186
186
187
186
375.0
376 JS
376.9
376^4
348^
348.6
340.0
3403
8483
8473
8473
8473
11963
1196.4
1196.6
1196.7
174.3
176.3
176.3
177.3
186
190
191
198
3763
377.8
377.7
878.1
3403
880^
3603
3613
8463
8463
8463
8453
11963
1197.0
1197J
1197.2
178.3
179.3
180J»
181.3
193
194
196
196
3783
879.0
379.4
379.0
361.7
362.2
362.6
353.1
845.6
8463
8463
•8443
11973
11973
1197.6
11973
182.3
183.3
184.3
186.3
197
108
199
200
380.3
380.7
381.1
381JS
8633
3643
364.4
364.8
8443
8443
843.7
843.4
11973
11963
1198.1
11963
186.3
187.3
188.3
189.3
201
202
203
204
381.9
382.4
382.8
383.2
3653
356.7
3S6.1
366.6
843.1
8423
8423
842.2
1196.4
11983
1198.7
11963
190.3
191.3
192.3
193.3
206
206
207
206
383.6
384.0
384.4
384.8
3673
367.4
3673
3683
8413
8413
8413
8413
11963
11993
11903
1199.3
194.3
196:3
209
210
386.2
386.6.
368.7
369.1
840.7
840.4
1199 4
11903
Volume.
Rela-
tire
Cu. Ft.
inlCu.
Ft. of
Water.
1663
1643
163.4
1623
161.6
160.7
1693
1583
168.1
1573
166.4
156.6
1643
1543
153.3
lfiS.4
151.6
1603
1603
1403
1483
1473
1473
1463
1453
1443
144.8
1433
1433
142.1
141.4
1403
140J
1303
1383
138.1
1373
1863
136.8
135.7
136.1
1343
3374
2360
2346
8318
8306
2.480
8.467
8.464
2.441
2.488
2.416
2.408
2380
2379
3344
8381
2310
8387
8.876
3366
3.865
8344
8.3S6
8313
8303
8.193
2.188
2.174
3.104
2.154
.4118
.4MB
3168
31S
.4414
.4477
i
PBOPBBTIEB or SATURATED STBAIL
1411
^^^^P^^^^H ^^^B^^^^V^^^n^^^O
TWMM OW •▲TIJKi
8l1«]»
rnVMAm^ OonMMMtf.
Pounds per
kiuare Inch.
H
Heat Units In One
Pound above 32® F.
Volome.
** o S
ij
<
^1
Relap
tiye
Speclflo
On. Ft.
inlCn.
Ft. of
Water.
Ou. Ft.
inl
Lb. of
Steam.
|5S
190.8
1973
1903
1903
211
212
213
214
886.1
886.6
386.9
8873
8003
360.0
360.4
3603
840.1
8383
8393
830.2
1199.7
11903
11903
1200a
133.9
1333
1323
1323
2.145
2.186
2.126
2.117
.4663
.4684
.4706
.4726
soaa
9013
2023
9033
216
216
217
218
887.7
888.1
8883
8883
861.3
361.7
362.1
8633
888.9
838.6
8383
8883
1200.2
12003
120O.4
12003
181.6
131.0
130.4
1203
2.108
2.096
2.089
2.080
.4747
.4768
.4789
.4810
20«3
2063
2063
2073
219
220
221
222
8803
3893
890.1
8903
8823
863.3
883.7
864.1
8373
8873
8373
887.0
1200.7
120O.8
1201.0
1201.1
1293
128.7
128.1
1273
2.070
2.061
2.062
2.048
.4831
.4852
.4878
AIMS.
2003
2063
2103
2U3
228
224
226
228
8803
891.2
8913
3923
8643
8643
805.8
3663
836.7
836.4
836.1
8363
12013
12013
1201.4
1201.6
1273
1263
1263
125.4
2.085
2.027
2.018
2.010
.4916
.4836
.4966
.4977
2123
2133
2143
2163
227
228
229
290
892.4
8923
893.2
8963
866.1
8663
8663
8673
836.6
836.3
835.0
834.7
1201.7
12013
12013
1202.O
1243
124.4
123.9
1233
2.002
1.903
1364
1.976
.4098
3019
3040
3061
2163
2173
2183
2193
281
232
238
234
8983
8843
394.7
896.1
867.7
868.1
3883
8683
834.4
834.1
8333
833.6
1202.1
1202.2
1202.4
12023
1223
122.4
1213
121.4
1.968
1360
1.962
1344
3082
3108
3124
3146
2903
2213
2223
2233
236
236
237
288
8963
3863
3963
896.6
869.2
869.6
370.
370.4
833.4
833.1
832.8
8323
1202.6
1202.7
12023
12023
1203
120.4
1193
119.4
1.936
1328
1.921
1318
3166
3186
3207
3228
2St3
2263
2283
2273
239
240
941
242
887.0
807.4
3973
388.1
870.8
371.1
3713
8713
832.2
832.0
831.7
831.4
1203.0
1203.1
1203.2
1203.3
1193
118.5
118.0
1173
1.905
1.898
1.891
1.884
3249
3270
3291
3312
2983
2293
2803
2313
248
244
946
246
8083
8963
380.2
889.6
3723
372.7
873.1
873.4
831.1
8303
830.6
830.4
1203.4
12033
1208.7
1203 8
117.1
116.7
116.2
115.7
1.867
1.868
1.861
1.863
3332
A158
3874
2823
2333
2843
2353
247
248
910
250
400.0
400.3
400.7
401.1
8733
874.2
874.6
875.0
830.1
829.8
8293
829.2
12033
1204.0
1204.1
1204.2
1153
1143
114.4
1143
1346
1.839
1.832
1.826
3416
3436
3457
3478
2383
2113
2SS
2B6
402.1
408.1
876.0
877.0
828.5
8273
12043
12043
112.7
111.4
1.806
1.785
3540
3603
PROPBBTIBS OP •AWaiA.VKD «XB AM — OmtlBKi.
g 2 te ia\~*"_^ p.\ '
a 3 S^n*,5ll Cn.Ft. Cu. Ft.l
-3 S ? 5 \ It gȣ\vn 1 Co. In 1 Lb.
406.e 3T«.£
vn.2 381^
763 if
1 laoa-i ',
1M.I
l'.7»
SSI!
1(».S
10L5
1(0.1
l.fC3
i'.o»
i2oe.i
1
i.cai
1.M
1.591
1.KS
iaw.7
i.Bai
isa
s
1210.2
1:S
13
1211*
laiaiB
1213.3
IS
IJU
1213.7
1217.7
E.71
11
i
111
1236:7
618
1
:«
123S.0
13*0^
13M.7
3».«
ia*e.7
J1.4
•m
a s
SUPERHEATED STEAM.
1413
A1JPK1IBCBATBD ftXBAM.
Dry sattirated steam, after being heated to a higher temperature than that
corresponding to its preBsure, is called superheated steam.
The Dehavior of superheated steam Is similar to that of gases ; it is a bad
eonductor of heat, and can lose some of its heat without becoming saturated
or wet steam.
Superheated steam has a greater volume per unit of weight than saturated
•team at the same pressure.
Pressure, Pounds.
70
116
170
T^ol.* at 390° F
ITol. at 670° F.
Vol. at 750° F
1.1
1.33
1.67
1.06
1.29
1JS2
1.02*'Lenke"
1.M
1^
Satnrated steam in engines condenses during admission to 20% to 26% of
the quantity admitted, causing a large part of uie low theoretical efficiency
-vben it is used.
Superheated steam does not condense during this period If sufficiently
superheated. 600° to 700^ F. is the temperature to which steam should be
superheated to get its fullest benefit, engines must be built to stand this
high temperature, or its use should not be attempted.
For piping to convey superheated steam, copper is not suitable, as it loses
about 40% of its strength at the high temperature.
Wrought iron and steel with long lengths, and few flange Joints, have
proTed to be the best.
The expansion at 100^ F. is about 4^ inches in 100 ft., and must be taken
care of in the design of steam lines.
Superheated steam can travel at 30 to 40% higher Telocity through steam
porte than saturated steam.
l^sd»ric«tlOM of B»giM«s Uslar Avp«rli«Ated St«ABB«
A 120 1.H.P. Engine uses 4 lbs. of oil per 24 hours for lubrication.
A 300 1.H.P. Corliss Ck>mp. Engine uses 2.2 lbs. of oil per 10 hours, both
cylinders.
use,
placed
temperature.
The manufacture of separate superheaters in the United States is at pres-
ent Tery limited, but abroad many types are in use, and are described in
Dawson's Pocket Book.
■ij of IMITereMt Types of Steaas Bngines UbImc
Svp«r]i«ot«!d Atoonit
(W. W. Christie, in Railroctd Cktzette, March, 1903.)
The Tarious results given herewith should not be compared with each other
on the basis of water per horse-power per hour, as pressures and other con-
ditions are different, but the economy arising from the use of superheated
steam over the use of saturated steam In the same engine can properly be
compared by one percentage diagram.
The following tests (A. S. M. £., Vol. zxi, p. 788) were made by Mr. £. H.
Foster, on a Worthington duplex direct acting triple expansion pumping
engine, baring six cylinders arranged in tandems of three on each side. The
engine was fitted with the Schwoerer patented superheater.
• Compared with saturated steam.
1414
STEAM.
TMtNo.
1.
8.
8.
4.
fi.
I.H.P
10&3
0.
S1.8
106^
0.
21J
108.
118.6
IBS
106.
122i^
l&S
MBJ
Superheat, deg. F
Steam per pump H.P. per hr., lbs.
U7J
The areraAe economy as shown by the abore tests in using
heated 119.6° F. is 14.1 per oent over that of saturated steam.
Perry, in the " Steam Engine," sires the results of sereral tests on aOor*
llss eompottud engine with steam jacketed oylindeis when devoloping sbost
fiOO H.P. With saturated steam at 96 lbs. pressure the steam oonsvmpiKiB
was 19.8 lbs. per indicated horse>power per hour, but when the steam w
■uperheated 118° F. the steam oonsumption dropped to 16.6 lbs., a gain of
90.8 per cent. Other tests on a single expansion engine equipped with s
Schmidt superheater gaye. when onng saturated steam, an economy oC M
lbs. per I.H.P. per hour, when using steam with 300^ superheat the rteME
oonsumption was 17 lbs., showing 66.8 per oent increase in faror of the 1st-
ter method.
In a paper read before the Society of German Engineers in 1900, Omst
Hunger reported a test of a Tertical cross eompouna pumping engine with
23.6 in. and 37.4 in. z 31 JS in. cylinders and running at 40 r.pjn. At 16 Iba
pressure the steam consumption was 20J& lbs. with saturated steam. Wltk
steam superheated 180JS° and a pressure of 180 lbs., the steam oonsumptasn
became 12.9 lbs., or a gain of 30.7 per cent orer saturated steam at the lowv
pressure.
Again, tests of a 3,000 H J?. Tertical triple eznansion engine at the Berfis
electric light works (Sngineering Record^ rol. xlii, p. 316) snow that a gslaaf
12JS, 17.9 and 18.7 per cent results from superheating the steam 181, fiisad
264° F. respectively.
Other tests in Bavaria, with a Snlser oompound engine (Etufimeering Nem»
Tol. xli, p. 213), give a gain of 16 per cent with steam superheated ll4\lfti
per oent when superheated 121°, and 26 J) per oent when superheated naPf.
160
UKRHIAT IN
no. 12.
Bcomoaiy' of fti
The aeeompanyingdlsf ram* has been obtained from the abore tests by
plotting the dearees F. oxsoperheHt as abscissa and the per oent of eoonnny
as ordinates. Inspection of this diagram shows that the greatest eoonony
results in the use of superheated steam in simple engine, as might be ex-
pected. On the other hand, marked economies are shown for compound sad
triple expansion engines, but the percentage of gain decreases as tihs was*
her of expansions increases.
* W. W. Christie.
CONDENSATION IN STEAM-PIP£S.
1415
(W. w. c.)
Ko T9rj satisfactory figures are found for the absolute eondensatloo
louses Id steam pipes, most of reported tests being compared with hair felt.
0j012 lbs. per 24 hours per sq. ft. of pipe per d^ree Fahr., difference in
temperature of steam and external air, which may be used in calculations,
Ss bsLsed on the following :
Sq.ft.
Sur-
face.
Lbs. of Water.
4-
if*
a
262
Lbs. Water per
degree 24 hours.
Test by.
in 94
hrs.
per
sq. ft.
in 24
hrs.
Corerlng.
Bedle A Bauer.
4iao
11315
2.74
J)104
Asbestos.
Morria.
3892
9300
iM
234
.0103
Asbestos.
Brill.
306
.0106
Magnesia sectM.
Norton.
816
.0126
Magnesia.
The last test by G. I^. Norton (Trans. A. S.M. E., 1808) was made with the
utmost care. Mr. Norton found thai a pipe boxed in with ebarooal 1 inch
minimum thickness was 20 per cent better insulated than when magnesia
waa used, corroborating Mr. Reinhart's statements concerning his experi-
ence using flue dust to insulate pipes.
ivd Skir- — The battleship *• Shikishtana " carries 25 BelleTllle
boilers capable under full steam of doTeloplnff 16,000 I.H.P. In the main
ensines besides working the auxiliaries, each Doiler supplying steam for
16ffI.U.P. When at anchor, one boiler under easy steam, i.e., evaporating
from 9 lb. to 10 lbs. of water from and at 212^ F., per pound of coal— was
Just able to work one 48 K.W. steam dvnamo at about naif power, together
with one feed pump, and the air and circulating pumps conneetea with the
auxiliary oonaenser. into which the dvnamo engine exhausted; bMides
working a fire and bilge pninp occasionally.
The dynamo was about 100 ft. of pipe length away from the boiler, the
total range of steam pipe length connected being 600-000 ft.
Performing the first-mentioned service with only one boiler under stesm,
the coal burned varied from 3^ to 6 tons per day of 18 hours, for about 66
I.U.P., or about 7 lbs. per indicated horse-power at the best to 10 lbs. at the
worst, an average of 8 lbs. and over, which shows that more than half the
fuel must have neen expended in keeping the pipes warm. All pipes were
well covered and below decks, and machinery in first-class condition.
(London-Bngr.)
KeAttar np«a« ~ To determine the boiler H.P. necessary for heating,
It may be assumed that each sq. ft. of radiating surface will condense about
0.3 lbs. of steam per hour as a maximum when In active service ; thus 20,000
sq. ft. times 0.8 r: 0000 lbs. of condensation, which divided by 30 gives 200
boiler horse>power.
Oondensed steam In which there is no oil may be returned to the boiler
with the feed-water to be re-evaporated.
1416
STEAM.
or
mAVRE UffVO
VAIKKOVA MiOirKJ
(D. K. Clark.) .
AtwolQte
Oatside
Velocity of
Actual Ve-
WelgbiDw-
Preasttreiii
Boiler per
Pressure
per Sq.
Batioof
Expulsion.
Outflow at
Constant
locity of
Outflow
^'lS^^SS"
8q. Inch.
Inch.
Density.
Expanded.
perMinms.
LlM.
Lbs.
Ratio.
Ft. per Sec.
Ft. per See.
Lita.
75
74
1.012
227i5
230
16.0
75
73
1.037
886.7
401
2SJ5
75
70
1.063
490
521
86.S8
75
«5
1.136
660
749
48.38
75
61.62
1.108
736
876
53417
76
60
1.219
765
933
66.U
75
50
1.434
873
1262
64.
75
45
U75
890
1401
65.91
75
48.46, 68 %
l.OM
890.6
144fiJ(
66.3
75
15
1.6M
890.6
1446 JS
65.3
75
0
1.624
890.6
1446.5
65.3
When, howerer, steam of yaryina initial pressure is discharged into the
atmosphere— pressures of which the atmospherio pressure is noC man
than 58 per cent— the velocity of outflow at constant density, that is, sap-
posing the initial density to be maintained, is given by the formula—
r= 3 JS963 VA,
where Kr: the velocity of outflow in feet per minute, as for steam of ths
initial density, h = the height in feet of a column of steam of the giTea
absolute initial pressure of uniform density, the weight of which is eqwl tQ
thepressure on the unit of base.
The following table is calculated from this formula :
^
oiJ!m<ow OF rnvMAm isrvo vmm avm
0«PlEBm&
(D. K. ClarlK.)
Absolute
Initial
Outside
Ratio of
Velocity of
Actual Ve-
Weight Dis-
Pressure in
Pressure
Expansion
Outflow at
locity of
Outilow,
charged ptr
Boiler in
in Lbs. per
Sq. Inen.
in
Constant
8a. Inch of
OrifloeperJUs.
Lbs. per
Koule.
Density.
Expanded.
8q. Inch.
Lbs.
Lbs.
Ratio.
Ft. per Sec.
Ft. per Sec.
Lbs.
26.37
14.7
1.624
863
1401
22.81
80
14.7
1.624
867
1408
26.81
40
14.7
1.024
874
1419
86.18
45
14.7
1.624
877
1424
89.78
50
14.7
1.624
880
1429
44.06
00
14.7
1.624
886
1487
62A
70
14.7
1.624
880
1444
OIjOT
75
14.7
LOM
891
1447
66.80
90
14.7
1.6M
895
1454
1T.94
100
14.7
1.624
898
1459
8631
115
14.7
1.624
902
1468
98.76
135
14.7
1.624
906
1472
115X1
166
14.7
1.624
910
147B
issjn
165
14.7
1.624
912
1481
140L46
215
14.7
1.624
919
1483
18U8
STEAM PIPES.
1417
R«nklne layi the Telocity of steam flow in pipes should not ezeeed 6000
Beet per minute (100 feet per second). As increased size of pipe means in-
ireased loss by radiation, care shoula be taken that in order to decrease the
relocity of flow, the losses by radiation do not become considerable.
TUe quantity discharged per minute may be approximately found by
Etankine's formula (" Steam Engine," p. 298), FT = 60 op -7- 70 = 6 ap •>- 7, In
vhich W z= weight in pounds, a = area of orifice in square inches, and^ ==
ibaolnfee pressure. The results must be multiplied by i; zr 0.93 for a short
pipe« and oy A; = 0.63 for their openings as in a safety valve.
Wb«re steam flows into a pressure greater than two-thirds the pressure In
Ihe boiler, IT = 1.9 aifcV(D~rf) rf, in which d = difference in pressure in
pounds per square inch oetween the two sides, and a, p. and 1; as above.
■ultiply the results by 2 to reduce to h.p. To determine the necessary dif-
ference in preasnre wnere a given h.p. is required to flow through a given
opening.
2 14
14 a*k'
Vlow of StoABi Xhroagrli Ptpee.
(G. H. Babcock in ** Steam.'*)
The approximate weight of anv fluid which will flow in a minute through
•ay given pipe with a given head or pressure may be found by the formula
W=zS7k/
D(pi — Pt)d^
o-^o
ill which W=z weight in pounds, d = diameter in inches, 2> = density or
weight per cubic foot. p. =: initial pressure, p^ = pressure at the end of the
pipe, and L = lenffth in reet.
The following table gives, approximately, the weight of steam per minute
which will flow from various initial pressures, with one poujid loss of pree-
tare through straight smooth pipes, each having a length of 2(0 times its
own diameter. For sixes below 6 inches, the flow is calculated from the
actaal areas of " standard " pipe of such nominal diameters.
For h.p. multiply the flgures in the table by two. For anyother loss of
EBure, multiply b y the square root of the given loss. For any other
th of pipe, divide 240 by the given length expressed in diameters, and
tiply tne fleures in the table by the square root of this quotient, which
will give the flow for 1 pound loss of pressure. Conversely dividing the
riven length by 240 will give the loss of pressure for the flow given in the
table.
Table of Flow of Steam Througli Pipes.
Initial Pres-
sure by
Oange.
Lbs. per 8q.
Inch.
1
10
20
80
40
60
60
70
80
90
100
120
150
Diameter of Pipe In Inches. Length of each = 240 Diameters.
1 U 2 2i
3
Weight of Steam per Min. in Lbs., with 1 Lb. Loss of Pressure.
1.16
1.44
1.70
1.91
2.10
2.27
2.43
2J57
2.71
2.83
2.95
3.16
3.46
2.07
6.7
10.27
15.46
25.38
2JJ7
7.1
12.72
19.16
31.46
8.02
8.3
14.94
22.49
36.94
3.40
9.4
16.84
25.35
41.63
3.74
10.3
18J>1
27.87
46.77
4.04
11.2
20.01
30.18
49.48
4.32
11.9
21.38
32.19
62.87
4.68
12.6
22.66
34.10
66.00
4.82
13.3
23.82
85.87
68.91
6.04
13.9
24.92
37.62
61.62
6.26
14.6
25.96
38.07
64.18
6.63
16JS
27.85
41.93
68.87
6.14
17.0
30.37
46.72
76.00
46.86
68.06
68.20
76.84
84.49
91.34
97.60
103.37
108.74
113.74
118.47
127.12
138.61
1418
STEAM.
Vabie •f now of Btmt
InltUl Prw
euro by
Gang©.
Diameter of Pipe In Inches. Length of Each = 2t0 DIasketen.
6
6
8
10
12
15
18
Lbs. per Sq.
Inch.
Weight of Steam per Min. in Lbe., with 1 Lb. Loee of
Pl«Mi»
1
77.8
116.9
211.4
841.1
602.4
804
1177
10
06.8
148.6
262.0
422.7
aS2J(
996
I4B
20
112.6
168.7
807.8
406.6
731.8
1170
17U
90
126.0
190.1
846.8
609 J»
824.1
1818
1999
40
139A
20O.O
881.8
616.8
906J)
1460
tm
60
160.8
226.0
412.2
666UI
979 J(
1667
2294
00
161.1
241.6
440JS
710.6
1046.7
1675
dIH
70
170.7
266.8
iMA
752.7
1106J(
1774
2991
80
179 JS
269.0
400.7
T91.7
1166.1
1866
2531
00
187.8
281.4
613.3
828.1
12190)
1961
28B6
100
106.6
288.1
634.6
862.6
1270.1
90SS
2935
190
200 J»
814JS
678.7
926.6
1863.8
S181
sm
160
228.8
343i)
625.6
1000.2
1486.6
837B
9m
The lois of head due to getting up the Telooity, to the friction of tte
steam entering the pipe and piunlng elbows and Talvea, will reduce Urn
flow given in the table. The reelstance at the opening and that at »
globe TalTe are each about the same aa that for a length of pipe eqoal It
114 diameters diTided by a number xepretented by 1+ j-* ^^ <1m aiat«f
pipes giren in the table these corresponding lengths are :
» 26 M
2
H
8
4
6
6
8
41
if
62
60
66
71
79
10
84
12
IS
The resistance at an elbow is eqoal to } that of a globe ralre.
eqniralentB — for opening, fur elbows, and for valTcs— must be added ia
each instance to the aotoal length of pipe. Thus a 4-ineh pipe, 190 diaae-
ters f40 feet) long, with a globe valre and three elbows, would do eqniTalflnt
to 120 4- 60 + 60 4: (3 X 4m := 800 diameters long: «nd 800+di0=l(. It
would therefore haye 1^ lbs. loss of pressure at the flow giren ia the taUs^
ordelirer (l-i- Vi{s .81^, 81.6 per oent of the steam with the aameatti)
loss of pressure.
Bq«AtlOM of PI
(Mo«ai).
It is frequently desirable to know what number of one also of pipes win
equal in capacity another giren pipe for delirery of steam or water. At
the same Telocity of How two pipes delirer as the squares of their inteml
diameters, but the same head inll not produce the same Telocity in pipaiof
different sLses or lengths, the difference being usually stated to rarr as tlis
square root of the flfth power of the diameter. The friction of a flsid
within itself is rery slight, and therafore the main resistance to flow is tbe
friction upon the sides of the conduit. This extends to a limited distaaes,
and is, of course, greater in proportion to the contents of a small pipe thsa
ii^i^'''^* ^} ^^-y ^ approximated in a giren pipe by a constant muUi-
Pl><^^)>7 the diameter, or the ratio of flow found by dirldlng some power of
the diameter by the diameter increased by a constant. (£reful compari*
sons of a large number of experiments, by different inrestigators, has ds-
▼f loped the following as a close approximation to the relatlre flow in dpti
of different sises under similar conditions :
JFca ,
«- ^ . ^ V rf + 3.6
W being the weight of fluid delivered in a given time, and d bstag Ihs
internal diameter in inches.
STEAH PIPES.
Mn. and In applvlnc tbb ral« ItU aeowu
whJcb *ra giiaa Id Uia folloiriiis Uble :
Title f t—J»r< Mbm BtjiaM »■* Ci
1
DUmtor.
1
Dlkmitar.
i
1
DUD>t«r.
1
1
1
IT
2^
8^
SM
it
8.ai
18
Tba tol lowing table fiT«a tbe niunber
aqoat In dellTery oUmt laroer pips of thi
ji.i m per portion aboTi "'
! ons iln required to
.. _., , _ihand under ttie ume
, The apper portion aboTe the dluoDal line ot bluike pertaltii t^
" iteaiB and fas pipei, while the luver portion Is for pipe of the
imal diauuten (fren. TheOsureaglTen In ihclaUeoppoiltethe
raqulred (o aqnal on* of (he laigat.
ij two liie* li the nnmber of t
u- w
« 1>
U'
!!■ **
to ''
in;
5< 5
f:j:
>,. St
1,1.
i""i'"i'"x';"j, T n
<
^
PBOPEBTIES or SATURATED STEAU.
1411
ipmopsm
inM OV BAmWUkXmHB BTMAm^ OanHnm^.
PoaudB per
-8
Heat Unite in One
Pound sboYo 32^ F.
Volume.
II
<
ri
4
JllJ
X
ReUr
tire
Speolflo
Cn. Pt.
inlCu.
Ft. of
Water.
Cu. Ft.
inl
Lb. of
SteAm.
3^1
^51
1963
1273
1263
1283
211
212
213
214
888.1
8863
3863
8873
369.6
3803
360.4
3603
840.1
8393
8383
839.2
1199.7
11993
11993
12004
133.0
1383
132.8
132.2
2.146
2.136
2.126
2.117
.4663
.4684
.4705
.4726
2003
2013
2023
2083
216
216
217
218
887.7
888.1
8883
3883
8613
361.7
382.1
8633
8383
838.6
8383
8883
1200.2
12003
1200.4
12003
1813
131.0
130.4
1293
2.106
2.008
2.088
2.080
.4747
3768
.4789
.4810
2043
2063
2083
2073
219
220
221
232
3893
889.8
880.1
8903
862.9
363.3
368.7
364.1
8373
8873
8373
887.0
1200.7
12003
1201.0
1201.1
1293
128.7
128.1
1273
2.070
2.061
2.062
2.048
.4831
.4852
.4878
2083
2003
2103
2113
223
224
226
228
380.8
891.2
391.6
802.0
3643
3643
3663
3663
886.7
836.4
836.1
8363
1201.2
12013
1201.4
1201.6
1273
1263
1263
125.4
2.086
2.027
2.018
2.010
A915
.4936
.4966
.4977
2123
2133
2143
2163
227
228
229
280
892.4
8923
803.2
8083
366.1
3663
8663
3673
836.6
8363
836.0
834.7
1201.7
12013
1201 3
12023
1243
124.4
123.9
1233
2.003
1.993
13M
1.976
.4896
3019
3010
3061
2183
2173
2183
2193
281
292
238
234
393.9
8943
394.7
396.1
367.7
368.1
3683
3683
834.4
834.1
833.9
833.6
1202.1
1202.2
1202.4
12023
1223
122.4
1213
121.4
1.968
1360
1.962
1.944
3082
3108
3124
3146
2203
2213
2223
2383
236
236
237
288
8063
3963
896.3
3963
809.2
369.6
370.
370.4
833.4
833.1
8323
8323
1202.6
1*202.7
1202.8
1202.9
1203
120.4
1193
119.4
1.986
1.928
1.021
1.913
3165
3186
3207
3228
2943
2363
2963
2373
239
240
241
2«2
387.0
397.4
3973
388.1
870.8
371.1
3713
8713
832.2
832.0
831.7
831.4
12033
1203.1
1203.2
12033
1193
118.6
1183
1173
1.906
1.898
1.891
1.884
3249
3270
.5291
3312
2983
2803
2803
2813
248
244
2<6
246
8983
396.9
309.2
3893
3723
372.7
373.1
873.4
831.1
830.8
8303
830.4
1208.4
12033
1203.7
1203 8
117.1
116.7
116.2
115.7
1.867
1.868
1.861
1.863
3332
A«3
3374
3396
2893
2833
2843
2863
247
248
248
2B0
400.0
4003
400.7
401.1
8733
874.2
874.6
875.0
830.1
828.8
8293
829.2
12083
12043
1204.1
1204.2
1163
1143
114.4
1143
1346
1.839
1.832
1.826
3416
3436
.5467
3478
2883
2113
263
266
402.1
403.1
8763
877.0
828.5
8273
12043
1204.9
112.7
111.4
1306
1.786
3640
3603
STEAM PIPES.
1421
-3
a
I
I 1
m 3
H -a
n i
S s
• 5
C
Mo
u
t
i
^ fc
1 1
I
«
s
hi
S
9
•
g 1^
fit 11
4B 9
•I
»
i
I
«
5
o
I
Vl
0
a
d
••4
00
a
u
9
«
■*»
a
••^
04
•«<Ki JO Of^vg
iS§§;
900J jod 8){U£i v) no^x
•»Boq
» SSSg!
•OT<yi JO 0}T«8
»ooj 29d 9%iuri ai saoq
00 «ee«)?40^^
•»flo^
3 BSSSI
•flwrf JO on«H
m • • ■ • ■
900J J9d B9{an. Of no^
J • • • • ■
^SISSSS
•woq JO oii^-rs
898S::SS
00 O) C9 A t- *^ ^
nsoT
■woT[ JO o]9«H
8$SSS8
unoH JOd nn;i
90oj[ J9d a^fuii u) Bso^
ot>t> 00^00
S8^9SS'
e«»^
'Boqaox Of 3a{J9AO0 jo SB9ni[0iqx
o *-<©»^«
1422 STEAM.
WMwm
(By H. O. Stott.)
Before Awardinc a oontrmot for ooTWinc the ■team plpee la the Menlwtf
Bailway Company^s power-hoaae, a caref ai inyeetiganon and teat of dlffcnA
tjpee and thlokneteee of oovering was made nnder the aathor'a dfreetloB.
The method adopted oonsiatea in oonpllng np ahont 900 feec of 34b. k«
pipe.
Sect
>tiona 16 feet in length were marked off on the atrai^t portkum of tki
pipe, and so arranged as not to inolnde any pipe oonpltuga or bends. Tvo
feet from eaeh end of each section heayr potential wirea were aoldsrad m
to the pipe, and at the extreme ends of tne pipe, oream copper ins^lsttd
cables were soldered on, the openlnn in the pipe hayinff been inerioariy
closed by means of a standard oonpluig and plug. One or these eablss na
direct to one terminal of a 2B0-kilowatt 260-volt steam-driren direet-ooipM
ezoiter. The oable connected to the other end of the pipe wna then coa-
nected to three ammeter shunts in series, in order to enable the readingi l»
be easily checked, after which it was carried through a drcnit bieaksr sad
switch to the other exciter terminal.
Inritations for bids were sent to all tiie principal pipe eorerinc nuuiaCM-
tnrers and Jobbers, specifying that each one wonld be expeeted to eorer sat
or more sections of the 8-inon pipe for a oompetitiTe teat, and that utamtki
from the successful bidders' ooyerlng would be analysed in the eoanpaaj'ft
chemical laboratory, and no ooyerlng accepted which defMurted mors tiaa
8 per cent from this analysis.
A special Weston Milli-Voltmeter was ordered, with which reading wen
taken from the potential wires, the latter all being broui^t to mercoryeafi
on a testing table near which the ammeters were also located.
were allowed to cool off to the ur temperatures before starting the test
The temperature of the room was kept between 27 and Si deginees (tat
(80 and 88 degrees Fahr., about) during the entire test. Baoh seettoahai
about 800 readings taken.
The method of test was to put a current of snfllclent quantity throe^
the pipe to heat to, say. 220 degrees Fkhr., and keep this current on for s
suffldent time to enaSle all sections to maintain a ocmstant tenn»«ratirB
(this period was found to be about ten hours), when readings ofue ■iiIB>
Tolt-meter were taken on each section with simultaneous a mm nt nr rnartingi
A constant temperature haying been obtained, it is evident that the wstti
lost in each section giye an exact measure of the energy lost in malntaiDiai
a constant temperature, and from the watts lost the B. T. U. are rssdilr
calculated. DIamm Ko. 1 shows the result of the test yalnes beli^ r»>
duced to loss in B. T. U. per square foot of pipe surface at yarious tesap^
atures in the curres. and at a temperature oorrespondlng to ateam at M
pounds pressure in the table.
After a series of readings had been completed, the current waa raiisl
suflloiently to giye approximately 60 degrees T^hr. rise tn the least eAdtitf
coyerlng, and malnuuned constant for ten hours, when another serits o(
readings was taken, and so on until the temperature of the pipe had leadkai
a point far aboye anything used in practice.
BTEAM PIPE COVERINGS.
1423
s
c
a i?
LO 1.S 1.4 l.« 1.8 SlO 12 £a 2.6 JLt S.0 ij 8.4 a.6 S.S «.« 4J
HEAT LOM:- B. T. U. per so. ft. op PIPE EURPACE PER MIMUT&
OIAQRAM I.
FlO. 14.
TOTAL BXeCmfi;~OOtT OF OOVERSNa AND HEA^r lOEt. 7
TlQ. 16.
{
1424
ST£AB£.
KCOMOHY OF lilFS'KmKHV
BTKSSSA OF COVBBXH«.
86 per cent magnesia used as basis.
The diagram shows that for two yearn, covering an inch thiok Is most
nomical. After two years the relative cost decreases quite fast witb is- <
crease in thickness; and at ten years, corering three inches tblok is far tts
most economical, and this without regard to pipe diameter.
JBIectricAl T«st •f
No of
Curre
2
8
4
5
6
7
8
9
10
11
12
13
14
16
16
17
18
19
»
21
Ck>Tering.
Solid Cork, Sectional
86 per cent Magnesia, Sectional ,
Solid Cork, Sectional
86 per cent Magnesia, Sectional
Laminated Asbesto Ck>rk, Sectional
86 per cent Magnesia, Sectional
Asbestos Air Cell [Indent] Sectional
(Imperial)
Asbestos Sponge Felted, Sectional
Asbestos Air Cell [Long] Sectional
" Asbestocel *' [Radial], Sectional
Asbestos Air CeU [Long], Sectional
*« Standard" Asbestos, Sectional
" Magnesian ", Sectional
"Bomanit" [Silk] Wrapped
86 per cent Magnesia 2 Sectional and i" Block
i" Plaster
it
ti
ti
i«
l«
«4
«i
II
II
II
2-1"
2-1"
•I
II
14
II
II
11
II
Bare Pipe [From Outside Tests].
Arer.
Thick-
ly
1.18
1.20
1.19
1.48
1.12
1.26
1.24
1.70
1.22
1.29
1.12
1.28
1.61
2.n
2.46
2.24
2.34
2.20
B.T.IT. jHest
Loss per, Saved
Sq.ft. at by
lOOlb.pr.
Cover-
ing.
1,4G2
2,008
2,0*8
2,130
2,123
2,190
2,333
2,662
2,750
2,801
2^12
1,482
1,881
1,387
1^412
1,466
1,666
1,668
13,000
87.1
815
84J
89.6
8SJ
8U
t 83,1
! 803
78.8
7U
18w«
88.8
89.4
88.7
89jB
88.7
88J0
87J
In a paper read before the A. S. M. B. in June, 1888, Prof. C. L. Kortoa
of the Massachusetts Institute Technol(^;y, gave a series of tables shoving
the results of tests. For the sake of brevity the descriptions of the diff»-
ent materials are omitted. The tables follow:
STEAM PIPE COVERINGS.
1425
Specimen.
A
B
C
D
E
F
G
H
I
J
K
L.
O
P
Name.
Nonpareil Gork Standard
Nonpareil Cork Octagonal
Manyille High Pressure .
Magnesia
Imperial Asbestos . . .
W.B
Asbestos Air Cell . . .
ManvUle Infusorial Earth
ManvUle Low Pressure
ManvUle Magnesia Asbestos
Magnabestos
Molded Sectional . . .
Asbestos Fire Board . .
Calcite
Bare Pipe
M.
O 9 • ?
•
11
B.T.U.
per Scj
RpeS
per Mi
Sfl
2.20
15.9
1.00
2.38
17.2
.80
2.38
17.2
1.26
2.45
17.7
1.12
2.49
18.0
1.12
2.62
18.9
1.12
2.77
20.0
1.12
2.80
20.2
1.60
2.87
20.7
1.26
2.88
20.8
1.60
2.91
21.0
1.12
3.00
21.7
1.12
3.33
24.1
1.12
3.61
26.1
1.12
13.84
100.
• • •
"27
16
54 .
35
45
59
35
65
48
41
36
66
• • •
Specimen.
HUac«lliameoaa llalMit«mcea.
B.T.U. per
sq. ft. per
mln.
at 200 lbs.
. 3.18
1.76
1.90
Box A, 1 with sand . .
2 with cork, powdered . .
3 with cork and infusorial
earth
4 with sawdust 2.15
5 with charcoal 2.00
6 with ashes 2.46
BHck wall 4 Inches thick . . 6.18
Specimens.
Pine wood 1 inch thick
Hair felt 1 inch thick
Cabot's seaweed quilt
Spruce 1 inch thick .
Spruce 2 inches thick
Spruce 3 inches thick
Oak 1 Inch thick . .
Hard pine 1 inch thick
B.T.U. per
sq. ft. per
min.
at 200 lbs.
3.56
. 2.51
. 2.78
3.40
2.31
. 2.02
3.65
. 3.72
Prof. B. C. Carpenter says that there is great difference in the flow of heat
through a metal plate between different media. In discussing Professor
Norton's paper he gave the values as shown in the following table as the
result of experiments conducted in his laboratory.
HciAt TraBSi
■sitted la Tlieni
lal Unite Ttaroa
larli Clean Caat-
Iron Plate
/b Incli Thick. ^Carpenter.)
Steam to Water.
Lard Oil to Water.
Air to Water.
Difference
of
Teroi>erature.
Degrees F.
Per Square Foot.
Per Square Foot.
Per Square Foot.
PerDeg
Total per
Per Deg.
Total per
Per Deg.
Total per
per hour
B.T.U
minute
B. T. U.
per hour
B. T. U.
minute
B. T. U.
per hour
B. T. U.
minute
B. T. U.
26
21
8.8
6.5
2.7
1.2
0.5
60
48
40
13
10.8
2.5
2.7
75
84
110
19.5
24.5
3.7
5.8
100
127
211
26
43.3
6.0
8.3
125
186
375
31i>
65.5
6.2
13
150
266
637
80
72.6
7.6
18.7
175
45.5
132
8.7
26.4
20O
52
173
10
33
aoo
78
390
16
75
400
20
133
500
25
208
The abore Investigation Indicates that the substance which surrenders the
heat is of material Importance, as Is also the temperature of the surrounding
media.
In estimating the effective steam-heatlng or boiler surface of tubes, the
surface in contact with air or gases of combustion (whether internal or
external to the tubes) is to be taken.
For heating liquids by steani, superheating steam, or transferring heat
from one liauid or iras to another, the moan surface of the tubes is to b«
STEAM PIPE.
1427
1
^ i
a 9
tA 00
mcq
I
_• ^« _• ^ • • • _■ T» ^ • • • • • •
00 C« C^ t« 10 ^ CO 0*
I
^illsp^H^^gis^
Cft^.l0^eoe4et«4l>^*i4«i4
I
S
9
9
I
2
•
e
9
3
^ ••• • • • • • ^» • •••
a a
s
a
s
• • • ^» • • • • • J» • ^^ ^1 » ^»
I
s a
I
• ^ • • _• • J • 13 • • • • • •
^^94e4CO^tDt^O»Or>4IOOO
gS3§i§§M§ipg§
V4FN FH Vi^ffl
*o5n«0 o<x|AtL 9«9-iV9X
cT<H ^o» aPt« ^«0 lo M *4 e o 8 <
•weunonix
.4
^^^^^^^%^^m'^^
mm
I
§
s
•2 <
I
• ••••■• • •• ■■•••
4* 9
I
a
.d
a
«H r4 fH e< ^n 4^« 10 «
1428
STEAU.
5s
I
H
^
s I
It
o & o « o
\%%%^mm^%\%%t\%%%%%%^mm.
8 ., . .
i
^
^iiS^liiiliiii^iiiliiiSiiisiiiil
S 8 8 S 5 Si Si « V 9 2 o ^ 8 CI to 4 ^ Q A o c« Z a 9 5 1« bsIh
9 «?
I •
I
o a
I
If
l|g§||i.§§§3S§|§ISg§J^8.^pgH^M«
H <=) 1*9
J^CWWc«circS'ft'«oi^eb^'^^io»»»««g;5e««j5ig»»;«ggj
BOILER-TUBES. 1429
Gollaipstiicr Pressure.
Bessemer Steel Tubes, Lap Welded.
A. S. M. £. Trans. 190$— B. T. Stewart.
P= 1000 ^1—^1 — 1600^^ iJ)
P=:86670^ — 1386 (B)
P-=. oolUpsing pres. lbs. per sq. In.
d = aato diam. of tube — inches.
t = thickness of wall — inches.
Use A for yalnes of P less than 681 lbs.
for values of -z less than 0.023.
a
Use B for valaes greater than these.
Material tested was 50000— 60000 lbs. tensile strength.
Up to 8'' diam. and 20 ft. long.
Itealatance of Tabes to Collapse.
Bulletin, No. 5, Exp. Station— Univ. 111., 1906 — A. P. Carman.
Where ratio ^ is greater than 0X13.
a. For brass:
P=r 93366 4 — 2474.
h. For seamless cold drawn steel :
c. For lap-wslded steel :
P = 96620^ — 2090.
a
P = 83270 *:s - 1026l
a
Where -= Is less than 0.06.
a
For seamless cold drawn steel :
P= 1,000,000 ^J^).
For lap-welded steel :
P= 1,280,000 ^^y
E8*%a -^'irs*!?'^^
5g»s^g_jsp"^^gXaf*'''^^
m « Sr * ej""™ gy "S3 A —5 ■■ "JVst
..r_».-_!!»<Sf-»S
sSE.-^nSS-^^jyat
,S=%2-»Sf-^^i^*^-
IgSWraM^-AA ' ^^i^i ""AU
.j.*fe,-.r!r-«<a*r— ^
..srs»«--xs*Sf-;^!r«5rS
sftT-S!?,— »«*:^-T^**5a
.s~S..— »*»Ttra*«ff
aaddaaaaidaaiiiaaaasi
II
l|i
PIPE BENDS.
1431
T0MsUe dtMtfm of Baits.
IMameier
Area at
At 7,000
At 10,000
At 12,000
At 15,000
At 20,000
of Bolt
bottom of
Ibe. per iq.
Ibe. per sq.
Ibe. per sq.
Ibe. per eq.
Ibe. per
in inohes.
Thread.
inch.
Inoh.
InclL.
Inch.
sq. Inoh.
, ,
.125
875
1,250
1,500
1,875
2,000
.196
1^2
14Hn
2,360
?»^
2^
1 '
.3
2,100
3,000
3,000
4,600
6,000
.42
2,940
4,200
5,010
6,300
«»i!S?
M
3,800
5,600
6,600
.5^
11,000
M
4,no
6,900
8,280
10,360
^•552
1
.78
6,460
7,800
9,800
11,700
16,600
1.06
7,420
10,600
12,720
15,900
2i»?59
I' '
1.28
8,960
12,800
15,860
19,200
26,600
1.S3
10,710
15,300
18,360
22,960
*^»52
1
1.76
12,320
17,600
21,120
96,400
35,200
1
248
14,210
20,300
24,360
30,460
i^'SS
8
2.3
16,100
23,000
27,600
34,600
46,000
^
8.12
21,840
31,200
37,440
46,800
62,400
8.7
25,900
87,000
44,400
66,600
74,000
The breaking strength of good American bolt iron Is usually taken at
60,000 lbs. per sq. in., with an elongation of 15 per cent before breaking. It
shonld not set under a strain of less than 25|000 lbs. The proof strain is
20,000 lbs. per sq. in., and beyond this amount iron should never be strained
in practice.
"Wwrnglkt Irom mr Mael Pipe.
(Crane Go.)
Fio. 17.
The radius of any bend should not be lees than 5 diameters of the pipe, and
a larger radius is much preferable. The lengtii X of straight pipe at each
end of bend should be not less than as follows:
5-lnoh Pipe Xz
6-inoh Pipe X:
7-lnehPIpeJr:
8-inch Pipe Xz
6 inches,
7 inches,
8 inches,
9 inches.
10-Inch Pipe X= 12 inches,
12-inch Pipe X=i 14 inches,
14-lnoh Pipe X=z 16 Inches.
»sSfa^^H'^8''^*?~^
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i
STEAU PIPE. JAM
■TAHDASD PIPB FI.A1I«B».
A. S. M. B. AOd Master Steam and Hot Watoi Fitters' AHoaUtlon atiu-
fLam, iKloptAd July IB. 18M. Medium prewure Iruslndea preaaurea ranejns
> — ! — ■71 J. -ui_t gj „P (u .jDd pouncla per aiiuare luct.
, , ^DlV 16, .
tnlov 76 pounds. High pri
T
Si]
iill
1
1]
16^ Sfl 4
TheilHiaoItwiMgli
high prcMnre. For med
« ? to 'JO Incbca dlomel'
When two ]lnee of flgnres oc
to M iDOhea ara for both mix]
inchea, tha left-baud columni
for blgb proaurea.
The andden lueraaae in diametera at IG inchea I
Uao of wroogbt-lron pipe, making with a naarlj
greater dlanieler dealrable.
When vrought-iroD pipe Is Deed, If thinner flu
iDlBolent, It la proposed that boaaea be osed to
(tandard lengths. This avoids the use of a reinf
^^T^na in [he third, fanrtb, Sf th, and laet coli
one beadlDg. the eiugle cDlurana op
high preeeores. BeJliiiilagiiiUi S4
ledluiD and the rfght-handlLnta are
I Inchea Is due to the poasible ln>er>
^
1434
STEAM.
Steam engines are often classed aeoording to the number of eyllBdcBl
steam passes In sneoession, and which are cufferent In slae»
Biffiple expansion,
Compouno,
Triple,
Qnadmple.
Any one of the aboTe classes, if run non-condeosing. Is called
sare, or non-condensing ; and if ran with condenser is called hlgli-]
or condensing.
Nowadays the abore classes are made in two types : high
all engines ninning above, say, 160 rerolntions per minvte ;~ and tar
all those running at less than 160 revolations.
This division is scarcely correct, as some of the longHrtrake ^■nf*'*ti
ning at 126 rerolvtione have more than 1000 feet niaton apecd, while
of the so-called Mffh tpeed machines exoeed 600 feet per mlnate
speed.
in selecting an engine for electrical work it is neeeBsary to see thst ^^^
machine is extra heavy in all Its parts; especiallvso for eleetrte rallvv
work, as the changes in load are often great and sodden, and In ciM« '
short oirenlt, engines are liable to be called on for tremeadoos Inetesw is
ontpvt, and should have no weak parts. This eepeeially appUes to 4^
wheels, of which a large number have bnrst on the laive* MkMW^fuakg
engines used in railway power-houses.
Bearings should all be of extra larse sise, eq»ecially so on the maiashsft
fournals of large direct-connected units.
The selection of sixe (horse-power) depends lanely upcm the ratine cite
connected electrical machinery and the number of hours it nma, muck Mug
left to the Judgment of the advising engineer. For direet-ocmiiected saili
it is not necessary to install an engine of greater rated eanaeity than tht
rated output of tne generator, as the engine will easily ears* ror cverksd m
the generator if rated at ^ cut-off. as is usual.
Some builders of engines rate their sixes for oonnecttons to dynamoiissB
to supply 1| h. p per k.w. capacity of the dynamo.
The selection of condensing or high-pressure englnea hastaithepaitdt*
pended largely on availability of an adequate suppTy of water fbr e(MhB»>
ug purposes ; but to-day the cooling tower with water enoi^^ to IB a
supply-tank once, and a regular supply for holler-feed, is a wy "
factory arrangement.
1
STEAM SNGINE8. 1436
I
(lYaiiMotions, A. 8. M. B., Vol. 23, 1902.)
^The Committee of Btandardixation of Enginee and Dynamoe has the
rare to enbmlt Its final report.
S. Xhe Committee's Investigation has oorered the standardisation of the
Alo^iFing points :
(1> The standard slses of units recommended.
<2) The oorrespondixig rerolntlons per mlnvte for these uiits.
(d> The sixes of shafts for the two classes of center-crank and side-
crank engines.
:•€> The length along the shaft required for the generator.
'6>) The height of aus of shaft oTer top of sob-base.
The width of top of sub-base.
Armature fit.
Orerload capacity of engines and generators.
Brush holders.
HoldingKloiwn bolts, keys, and outboard bearings.
Ma« of Vaite.
8. Our endeaTor has been to reduce the number of standard units to the
Sew«Bt slses. For reasons previously stated, the largest sise embraced in
mr list is SOO-kilowatt capacity.
In this connection our report covers the standardisation of dibxct-
BUKXBKT generators only.
]ft«T«l«tl4
4. These standard speeds have been chosen after investigation of the
ivafetioe of all the engine and generator builders in the coimtry. It will
be observed that we have provided for a permissible variation of speed of
ire per cent above or below the mean speed, which we recommend.
B. These are the result of analysis of the existing practice of all manu-
facturers, and a consideration of all the conditions affecting the diameter
of the shaft.
In order that the reason for the diameters of shafts that we have recom-
mended shall be thoroughly understood, we may explain that (especially in
shafts fbr side-crank engines) the permissible deflection has determined the
diameter. This, in some oases, is larger than would have been necessary
for torsion and bending If deflection did not have to be considered.
As cases sometimes arise where cross-compound engines or double engines
are oonnected to generators coming within our recommendation, and, as
such units require considerable laxger shafts than those given in our tables,
we deem it necessary to state, specincally, that our recommendations apply
only to engines of usual proportions, with the generator attached at the
side of, instead of between, the cranks.
•f Ctoaorsitor sa«mr tke Bhrnn.
6. We found that the praetiee of manufacturers required provision for
two classes, whioh may be called ** long " and " short *' generators.
1436 STEAM.
We hare oArefuUy eontidered the foot that for tbeM rvflag
generator and shaft, the encine builder hae to provide dtfferent
sab-base, and in order to rednce the expense of patterns here to a
our idea is that these patterns would be made so thai the end avv
the commutator can be extended the necessary amount, fire or six '
to take care of the increased length of bed.
Helrlit of Shaft.
7. There are two classes of generators to be provided for and«r
Those which are split yertically, and those which are split be
The former have a flat base which rests directly upon the flat tap of
sub-base, while the latter have feet which talce the wei^t of the
rator.
In order to arrange that the engine builders' patterns may be redoeed ts&'
minimum and still he stoelc patterns, which wul fit every style of mw'hh^
we hare chosen dimensions for height of axis of shaft abore top cf ti^
base, sufficient to allow for the yertically-eplit machines, and slso, «'
cept as stated later, to clear the periphery of the horisontaUy-^ft
machines.
As will be seen, the scheme provides for a main pattern to which pattana i
for the stools ana seatings for both horiaontally<«nd yerticallynqklit tea*' ••
ators can be attached before the pattern is sent to the foundry — stools it
the horiEontally*eplit machines, and rectangular seatings for Uie TertteaQy*
split machines.
In the case of the 160 and 200-kilowatt units, we have nrovided for &
recess in the top of the sub-base to allow the lower part of somehniae-
tally-split generator frames to be accommodated, and so to avoid vaMj
raising the center of the shaft. In the case of the TertlciJly-split ntsfMiMl
and those which are split horizontally and do not need tills recess, the Mf
of the sub-base will be flat and continuous.
W^idtk of Top of
8. This has been decided by examination of «Trig«i^ praetiee. sad «e
believe that the figures we have recommended will cover tiie nuuuMttiw
for all sixes of generators.
9. In the matter of armatoxe ftt« car zeeommeiidation is for what is kaonra
as a single fit.
We have obtained the opinions of manufacturers in respect to the alifo*-
ance to be made for a pressed fit, and And that allowances of x^« i'^ ^
shafts 4 inches to 6 inches, inclusive, and j^^ Inch for shafts ^ inehei to
11 inches, inclusive, represent the best existing practice.
The armature bore is to be the exact size given in the tAble, sad tti
allowance is to be made by the increase of diameter of engine shaft.
We believe, that in order to secure the best results, it will be neoeasT
to work to a definite gauge; to this end we recommend that thesenentff
builder furnish a gauge the exact diameter of the bore, and toe esgiB*
builder make the necessary allowance for the press fit, as reoommended.
OvorlosUI Ctaipacl^ of BMgiBoa mmA
10. Generator builders are frequently called upon to provide. dviM
short periods, for overloads of as much as 60 per cent, and. In ooetft**^
cases, of even 100 per cent. .
Bearing in mind that our reoommendatlons are enftirely for gtaodire
practice, we recommend that the standard overload rating of anv diree^
connected unit should not, in any case, exceed 26 per cent oi tut ttkA
capacity.
STEAM ENGINES. 1437
Brvsli Holders.
tl. We reoommend that the brnah-holder rigging shall be supported upon
• generator frame.
HoldUsff-dowK Bolte, SLeja, ttad OvflieaWi SeariMgr**
12. We reoommend that the holding-down bolts, shaft keys for securing
le generator hob to the shaft, and the outboard bearings, should be
mlshed by the engine builders.
In the table will be found columns showing sizes of shaft keys which
B recommend; also the number and size of holding-down bolts.
It will be noticed that we do not give any lengths for keys. We believe
best to leave the determination of the length of key for adjustment by
igine and generator builders in each Individual case.
Sizes of keys have been taken, so that standard rolled stock can be
aployed.
we recommend that the keys be made straight, and be used as feathers.
hey should therefore fit accurately on the edges, and not on the top.
toper allowance should be made in cutting the key way in the armature
Bb, so that there will be sufficient clearance at the top of the key.
13. In the course of our investigation our attention has been called to
• number of points, which, from their nature, are not exactly in the same
ategory as those on which we have made recommendations, but we con-
Ider them of such importance that we desire to olTer them as suggestions
or consideration by members of the Society, with a view to their Moption
t considered sufficiently meritorious.
ilagr Amsatare on Shaft. — Usually the contract definitely
wovides by whom this is to be done, but our suggestion is that if there is
lo such provision in the contract, it should be understood that the engine
lud generator builders shall agree who is to do this work, so as to avoid
iny dispute when the separate portions of the unit are delivered on the
tremisee.
B. Slo«r-Iitae. — For convenience in operation, and for the informa-
ion of engine and generator builders, we suggest that for units up to 76
Lilowatts, Inclusive, the floor line should come at the bottom of the sub-
Mse: and for units 100 kilowatts to 200 kilowatts, inclusive, the floor line
ibould be one inch below the rough top of the sub-base.
C Protectlnc CoasnsutAtors from Oil. ~ In view of the fact
:hat in some cases the distance between bearins and commutator is very
onall, it is well for engine builders to bear in mind that provision should
>e made to prevent oil xrom the bearing getting on the commutator.
A. Some generator builders have asked that the end of the shaft shall
^ drilled and tapped to facilitate, if necessary, the removal or placing of
the armature on tne shaft at the place of erection ; we suggest that this
l)e done.
B. In some cases, generator builders require special nuts, bolts, or fiz-
tnres for attaching generators to the shaft. Under these conditions we
inggeet that the generator builders should furnish all attachments to their
Htparatus that are not already specified tn our report.
V
1438
STEAM.
•
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BTEAM ENGINES.
■ mT TbHom* Ttp**.
By
Prof. R
C. Crpenter.
^^
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1440
STEAM.
UToBitMal Honie*power. — Now very little lued.
D = dia. cyL in inches.
A = areii of piston in »q. inches.
L = length of stroke in feet.
Watt gives, nominal H.P. = -^t"
Bonlton & Watt, nominal H.P.=z -^•
Kent glres as handy rule for estimating the h.p. of a single cyHnderoii^ i
— . This ru]e is correct when the product of the m.e.p. and pigtompesds
31,000.
The above rule also applies to compound triple and quadruple engiaM,iisil
is referred to the diameter of the low-pressure cylinder, and the h.p. of s
an engine then becomes
(dia. low-pres. cyl.)' „ » / wi x
^ ^ ^— = H.P. (roughly.)
ImUcAtod Hora« Power t I.H.P.— The power devek^ed ii,
the cylinder of a steam engine is correctly determined only by use of tib*
indicator, and comparisons and steam consumption are always caleabtei
on that basis.
M.E.P. = mean pressure in pounds per square inch, aa shown \j tfci
indicator card.
X= stroke of piston in feet,
n == number of revolutions per mln.
a = effective area of head side of piston,
tt/ = etf ective area of crank side of piston.
T TT T> [(a X m.e.p.) -f («/ X m.e.p.)] x Im
^•^•^•- »;o6o
For multiple cylinder engines, compute I.HJP. for each cylinder, aad sdl
results together for total power.
Bn»ke Horae-power.— The brake horsepower (B.H.P.> of an ei^te
is the actual or available horse-power at the engine pulley ; at any ma
speed and given brake-load, the B.H.P is lees than the corresponding ijSUt*
by the horse-power required to drive the engine itself at the riven iiperit
and with the pressures at the bearings, guides, etc, oorreapoiMing to As
given brake-load.
If W=. load in lbs. on brake lever or rope,
/= distance in feet of center of brake-wheel from line of
action of brake-load,
N=: revolutions per minute ;
then B.H.P.=^.
The mechanical efficiency df any given engine is lees the greater tfca
expansion ratio emploved, and of two engines of the same type, develcfte
the same power at the same speed, that which uses the higher degree of
expansion will have the lower mechanical eiHeienev. The effect of thii,
though not usually important, is to make the best ratio of expansion in say
given case somewhat less than that which makes the steam eonstnnptisn
per I.H.P.-hour a minimum.
The mechanical efficiencies on full load of modem engines range froaiS
to 95 per cent. Large engines have, of course, higher meohanieal effifl**?
cies than small ones (a very small engine may have as low a meehsBlaB
efficiency as 40 to 60 per cent, but this is generally due to bad design
insufficient care being taken of the engine), simple than componnd en
and compound than triple engines — at any rate when not very large.
Prof. Thurston estimates that the total mechanical loss in non-ocmd
engines having balanced valves may be apportioned as follows :—
bearings 40 to 47 per cent, pistons and rods S3 per cent, crank-pins 54 per e«t
slide-valves and rolls 2^ per cent, and eccentric straps 6 per cent. An wital*
anced slide-valve may absorb 26 per cent, and in a condensing engiaelhd
air-pump 12 % of the total mechanical Iom.
k.j
STEAM ENGINES.
1441
The object of building multiple cylinder englAee i«(
a» to use high steam pressure,
6, to get the greatest number of expanBlons from the steam,
e, to reduce the cylinder condensation.
Inot, Thurston says : " Maximum expansion, as nearly adfabatlfl at prae>
leable, is the secret of maximum efflciencv.*'
Although the theory of determining tne sixes of cylinders is perfectly
nderstood, yet there are so man v causes for yarying the results toat prac-
leallY to-day but little attention is given to calculaUons, the plan being to
■e dimensions such as have proTcd best practice in the past.
The proportions of cylinders are supposed to be such as to equally diride
lie number of expansions and work among them, and these dimensions
isve to be Tarled somewhat to meet the experience of the engineer.
QiTcn the initial pressure (absolute) i,P, and the terminal pressure (abso-
i P
nte) <.P., then the total number of expansions is 1?=-;^, and the num-
%er of expansions for each cylinder is as follows :
For compound ^E,
For triple expansion *^^,
For quadruple expansion *V£.
Better results are often obtained by cutting off a trifle earlier In the high*
pressure cylinder ; and this fact, in connection with the extent of reheaters
ind receivers, changes the actual ratios from the ideal to the practical ones
Bhown in the following table :
^■asbcr of JExpttMsloae for Condeiuilag' Tloylo— »
Abso-
lute.
Total
Expan-
sions.
Expansions in Each Cylinder.
Type.
1st.
2d.
3d.
4fh.
Single cylinder ....
Compound
rriple compound . • .
Qoadrnple compound .
66
145
^ 186
266
7
22
30
48
7.
4.8
3.2
2.7
4.6
3.1
2.66
3.0
2.6
2.66
For triple engines, Jay M. Whitham * recommends the following relative
fixes of cylinders when the piston-speed is from 760 to 1,000 It. per minute :
Boiler Pressure
(above
Atmosphere).
Hljzfa-Pressure
Cylinder.
Intermediate
Cylinder.
liOw-Pressnre
Cylinder.
lao
140
150
160
1
1
1
1
2.26
2.40
2.56
2.70
5J00
6.86
6.90
7.26
The following are the maximum, average, and minimum values of the
relative cylinder volumes of triple-expansion condensing engines, working
With boiler pressures of 150 or 160 lbs. per square inch above atmosphere, on
board 66 boats launched within the last three or four years : —
Hiffh-PresBure
Cylinder.
Intermediate
Cylinder.
Low-Pressure
(Cylinder.
kaximum value
iverage **
MlBimum ** ■
1
1
1
2.84
2.68
1.89
7JS6
6.n
4.50
JBoeieiif qf MecJUMnieal Enginurg^ 1889.
1442
STEAM.
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STEAM BNGINES. 1443
C«|Niclty.— Tn compound enffines with cranks at right
M[^«s the reeeirer capacity should be from 1 to 1J( times that of the
t>^la~pregsnre cylinder (Seaton), or not less than the capacity of the low-
inre cylinder (** Practical Engineer **). When the cranks are oppo-
__ the reoelTer capacitv need not exceed that of the steam passage nom
laigh-pressore to the low-pressure cylinder. The general effect of large
liTer capacity is to cause a drop between the pressnre at the end of the
-pressore enansion stroke and the beginning of the high-pressnre ex-
t stroke and low-pressure admission, thus increasing the power devel-
in the high-pressure, and decreasing the pewer deTeloped in the low-
ure cylinder ; this leads to a loss <» power in the engine, and one
irlfcieb — at any rate in ensines with cranks at right angles •> is greater the
more the receiyer capacity exceeds that necessary for free passage of the
ttea^m.
kMs P«rfa SMd Paaaarcia. — The areas of these should be such
Outt the mean linear Telocity of the steam does not exceed 0,000 to 6,000 feet
per minute ; hence, if
D =z diameter of cvllnder in inches,
A zrz area of cyllnaer in square inches,
a = area of port or passage in square inches,
S =. piston-epeed in feet per minute ;
* ~ 6,000 ~ tJsS
for mean Telocity of steam 6,000 feet per minute ;
__ AS ^J^S
**" 6,000 "" 6,366
for mean Telocity of steam 6,000 feet per minute.
Tbe lengths of the steam passages between the cTlinders and TalTcs
lihoald be as small as possible, in order to minimize clearance and reslst-
Anoe to flow of steam.
Condensers are principally of two types, tIx., Jet Condensers, in which
fhe staam and condensing water mix in a common vessel, from which both
are pumped by the aJr-pump ; and Surface Condensers, in which the steam
generally passes into a chamber containing a number of brass tubes, throaeh
which the condensing water is made to circulate. The latter form is usuafiy
adopted where water is bad, as it enables the same feed-water to be passed
throngh the boiler OTer and OTer again.
The capacity of a jet condenser should not be less than one-fourth of the
low-pressure cylinder, but need not exceed one-half, unless the engines are
Tery quick running ; one-third is a good aTerage ratio. Large condensers
require more time for forming the Tacuum, while small condensers are
IVanle to flood and oTcrflow back to the cylinders. The amount of condens-
ing water required per pound of steam condensed Taries with the tempera-
ture of the exhaust, of tne " hot-well/' and of the condensing water. (The
"hot- well*' is the receptacle into which the air-pump delivers the water
from the condenser.) ?rhe feed-water is obtained from the ** hot-well,'*
which should be maintained at 110° to 120° F. Sometimes CTcn 130° F. can be
obtsined with care.
The amount of cooling or tube surface depends upon the difference be-
tween the temperature of the exhaust steam and the average temperature
of the cooling water, and on the thermal conductivity and thickness of the
metal tubes. For copper and brass tubes in good condition the rate of
transmission is about 1,000 units (equivalent to about 1 lb. of steam con-
densed) per square foot per 1° F. dinerence of temperature per hour. With
the hot-well at 110^ ana the cooling water at 60°, the average difference is
26°, and 25 lbs. of steam should be condensed per hour per square foot. In
practice allowance must be made for tlie working conditions of the tubes,
and half the above, <.«., lib. of steam per 1° F. difference Is nearer the usual
allowance ; and under tne above conditions about 12.5 lbs. of steam would be
condensed per square foot per hour, which Is considered Terr fair work.
The tubes are generallT of brass, Ko. 18 S.W.O. thick, ana from | to 1 in.
diameter, aecormng to the length of tlf ? tubes ; they are usually | in. in
1444
STEAM.
diameter, and spaced at a piteh of l^ln., irhile Oie
also of braes, are li to 14 in. thick for } in tubes. The 1
when unsupported between plates, should not exoeed 12D
If zr= total heat of 1 lb. of exhaust steam in B T.U.,
t =: temperature V.^ of hot-well,
ti = temperature F.** of oooling water on enlering,
^ = temperature F.^ of cooling water on leaving,
Oi = quantity in lbs. of cooling water per lb of
6, z= ditto for surface condenser :
oftiw
steam for jet
t = ^"^^*^ for Jet condenser,
1 + Vi
«l=
H—t
f = .ff— Q, (/, — fj), for surface condensers.
N.B. H—t =1,060 approximately.
Values of Q* and Q. for different temperatures of cooling
1150, t = 110, and <s =: 100 in case of Q, :—
tertWhsaJTs
Values of f^.
40
60
1
60 70
m
Qt. . . .
15
17
21
26
36
«■-...
17
21
26
as
8S
Area of injection orifice should be such as to allow a velocity of tevci
water not exceeding lj500 feet per minute. It Is better to hare a large art*
flee and to control tne flow of water by an injection valve.
Area of orifice in square inches.
= lbs. water per minute -r 660 to 750.
= area of piston -r 260.
The cooling or circulating water in surface condensers should travel sooe
20 ft. lineally through the tubes. In small condensers, where this ii art
convenient, and the water only circulates twice through short tulMs, At
rate of flow must be reduced.
A replenishing cock should be fitted to allow of the passage of part of Ibe
circulating water into the air-pump suction to provide for water lost te
drains, blowing off, leakage, etc. This may have one-tenth, the area of te
feed-pipe.
A cock should be fitted close to the exhaust inlet for introducing caaitie
soda when required to dissolve srrease ott. the tubes.
Assume your engine to require 20 pounds of steam per horse-power psr
hour, or one-third of a pound per minute, and to exhaust at atmoei^eik
pressure. One pound oi steam at atmospheric pressure contains 1146.1 h^
units above 32°. One pound of water at this temperature contains approc-
mately 120 — 32 = 88 heat units above 82^, so that to change a pound oi ttesa
at atmospheric pressure into water at 120°, we should have to take froo it
1146.1 — 88 = 1058.1 heat units, and for one-third of a pound, 1068.1 -> 3=:
362.7 heat units. Suppose the injection water to be 00^. In heating to IST
each pound will absorb approximately 60 heat units, so that it would Uke
362.7-^60 = 5.88 pounds of injection water per minute per horae-pover
under the assumed conditions. A higher terminal pressure, higgler tem-
perature of inlection, less efficiency in the engine, or lower hot-wtO
temperature, will Increase this figure.
In order to cover all conditions, makers and dealers figure tiiata eoa-
danser should be able to supply from a gallon to a gallon and a half of Hh
CONDENSERS.
1445
aetlon water per minate for each Indioatod horBe-oower developed. The
mpausity of a dngle-aeting vertical air-pamp ahould be from one-tenth to
me-tw^elf th that of the cylinder; of a double-acting faoriaontal pump, from
me-«ixteenth to one-nineteenth.
Rector Condensers are made on the principle of steam injectors except
Aunt tike action is rcTerted, the cooling water takinc the place of the steam
a tbe injector, and the exhaust steam that of the leed-water. In order to
iBsnre their snccessf al working, the cooling water should be supplied at a
tfcead of 16 feet to 25 feet, either from a tank above or from a centrifugal or
vttier pomp. The amount of cooling water required is about the same as
Cor Jet condensing; the vacuum is from 20 in. to 26 in.
Some builders of ejector condensers advise that the exhaust pipe from
engi ji« be carried up to a height of 30 feet above the level of condenser dis-
9haurg9, then drop straight to condenser.
Increased momentum of the steam is very beneficial to a vacuum.
Thirty feet provides an ample safeguard against water flooding the engine
eylinder.
me«t#r CoBdeaeer Cs4p«cttfti
Bxl&sitist
Water.
S£!
Inlet.
OuUet.
^
1
2
1
1*
3
^
2
4
3
2|
6
8^
8
6
4
H
7
6
4
8
6
6
10
7
6
13
8
7
14
10
9
16
11
10
18
12
12
24
• • •
• • •
Steam
Condensed
per Hour,
Lbs.
200
400
800
1,600
2,000
3,000
4,000
6,000
8,000
12,000
20,000
28,000
36,000
00,000
Condensing i
Water req.
per Hour,
Gallons.
660
1,100
2,200
4,000
6,600
8,260
11,000
16,600
22,000
33,000
66,000
77,000
99,000
176,000
Suitable
for
Engines of
6-lOI.H.l*.
10-20 *♦
20^40
36-70
60-100
76-160
100-200
160-300
200^400
300-600
600-1,000
700-1,400
1,000-2,000
2,000-4,000
<(
li
««
41
«i
II
U
II
II
II
II
11
This type of condenser finds favor in large electric plants which are situ-
ated near abundant water supplies. An example of this is the Edison Station
of the Public Service Corporation at Paterson, K^J., where they have been
in use with great success for some years.
^AJr-pnnipe are used to draw the condensed water from the condenser to
the hot-well, together with the air originally contained in the water, or
which mav flna its way in through glands, etc., and with Jet condensers
they also draw the cooung water. A cubic foot of ordinary water contains
about .06 cubic foot of air at atmospheric pressure, whicn expands in the
condenser to about .4 cubic foot of air : hence the term air-pump.
The eflleienoy of a single-acting air-pamp may be taken at .6 to .4, and
generally A, while that of the doubleactiag pump may be .6 to .3, say .4 on
average. For iet condensing, the volume of the air-pump should be theo-
retically 1.4 times the volume of condensed + cooling water ;
working it should be from twice to thrice that required by theory.
V = volume of condensed water per minute in cubic feet,
F= volume of cooling water per minute in cubic feet,
n =: number of strokes (useful) of air-pump per mlnutei
A = volume of air-pump in cubic feet ;
for good
Or&
A=z2S
= 3.6
n
e+ r
for single4Msting pumps,
for double-acting purope.
Since, for surface condensing, the air-pump does not draw the cooling
water, and as the feed-water, being used over again, should not contain so
much air, it would appear that the air-pump might be much smaller
than for jet condensing. However, surface conoensers are frequently
arranged for use as Jet condensers in case of mishap, and with surface con-
1446 STEAM.
denslng a better vaoanm \b expected, 90 tliat for surfaee eoodeoilng tte tta-
pump is only sliffhtly less tluui for Jet eondeiuiixig. In aetoal prMtlee A»
air*pafnp is made from one-tenth to <me-twent7-flfUi the '*' *
the low-pressure cylinder, according to the number of exp
nature ox condenser, while a comparison of a nnmber of marine
different makers shows a ratio of one-sixteenth to one twenty^lxvt.
If expansion joints are used in the exhaust pipe, a copper bellowa }atatir
better than the ordinary gland and stulBng-box type, finroogih wbfeh ^k
apt to leak.
Air-pump ▼alTcs should hare sufficient area that the full quantffeyof sbs^
ing and condensed water in jet condensation in passing does not exesBda
▼Mooicy of 400 feet per minute ; in practice the area is larger than tltii. A
large number of small yalves is perhaps better than one or two large ralni
which are sluggish, owing to tilieir inertia. The elearance spaee betveea
head and foot valres should not exceed one-fifteenth the oap«eityGf tkt
pump as ordinarily constructed.
If a =: area through foot yalves in square inches, !
a. = area through head valves in square inchoa,
a •=. diameter of discharge pipe in inches, j
D = diameter of the air-pump in inches, 1
8 = speed (useful) in feet per minute ; :
^ = 860^^-
If there be no air vessel or receiver, d should be 10 per oent laxgor.
An air-pipe should be fitted to the hot-well one-fourth the diameter of
the discharge pipe.
ClrculMtlair JPampa. — The size of these depend chiefly on eonditiaai
mentioned for air-pumps, and thev may bear a constant relation to the ao^
pump as to size, or to the L.P. cylinders.
Air^pvMM. drculoHnff Pvmp, JkM»,
Single acting Single acting .6
Single acting Double acting .31
Double acting Double acting JS
or If V=. volume of cooling water in cubic feet per minute^
iS= length of stroke in feet,
n = number of strokes (useful) per minute,
f^rr capacity of pump in cubic feet,
D = diameter ot pump in inches ;
Circulating pump valves should be of sufficient area so that the mean v«Ib-
eiiy of flow does not exceed 8 or 4 feet per sec. High velocities tend to
wear out the valves, and cause undue resistance in the pump. In the poe-
tion and delivery pipes the velocity should not exceed GOO feet per roiiiite>
or for large and easy leads 000 feet per minute. Better results, however.
will be obtained by using larger pipes, so as to reduce tiie velocity, m»-
cially if the pipes are long. For single-acting pumps the suction may M
smaller than the delivery, if the pnmp be below the water-level.
If a = minimum area through valves in sqiiare Inches,
d = minimum diameter ot pipe in inches,
A = area of pump in square inches,
D = diameter of pump in inches,
8 = mean speed (useful) of pump in feet per minute ;
"-lio' *~~ir'
where K varies from 22 for small pumps to 25 for large pumps, while for the
suction of single-acting pumps it may be 87.
Air chambers should always be fitted, which for single-acting pumps mty
be twice the capacity of the pump. An air-pipe should be fitted to Uis
CONDENSERS. 1447
JglMst points of the water panages for escape of air to enable the eon-
■•iiser and pipes to ran fall, if the speed of the olrcalatlng pxmip cannot be
isaied Independently, it is adrtsable to fit a water valve between the two ends
tf the pump, so that the discharge may be varied to salt the requirements.
Strainers should be fitted to the inlet of the suction pipe, and the asgre-
pate area of the passages should be from two to four tunes the area of the
»lpe, according to the velocity of How in the pipe. Owing to difficulty
kxperienced in cleaning strainers when under water, they are sometimes
Ixed in a cast-iron vessel near the suction entrances to the pump, with a
loor arranged in some convenient position for cleaning.
W^mt Valve.— When the water level is below that of the pump, a foot
raive should be fitted iust above the surface of the water. A door should
be provided for examining the valve without disturbing the suction pipe,
[>r an air ejector may be used to chaige the pump.
cooiiiire TOWER vbat.
On August 2, 1898, during a run from 7 A..M. till 12 midnight, from the
dally records, the following data is reported by Vail, A.S.M.E. Trans. Vol. 20.
Maximum. Minimum.
Temperature, atmosphere 109^ 88"
Temperature, condenser discharge to tower . . . 128" 106"
Temperature, condenser suction 96° 91"
D^rees of heat extracted, through tower ... 32^ 21"
Speed of fans, revolutions per minute 160 140
Vacuum at condenser 26 20
StrolKCs of condenser pump 60 88
Founds, boiler feed 121 100
Temperatare, boiler feed 212" 209*
Snglne, horse-power developed 900 H.P. 400H.P.
A continuous heavy load was carried during the entire 17 hours' run.
This was not a test record, but simply daily service.
Another day, November 5, 1888, from a 20 and 36 X 42 tandem compound
eondensing Corliss engine, the conditions were as follows :
Engine revolutions 120permin.
Bteam pressure 112
Vacuum at condenser 26
The area of the cards shows the work done in high pres-
sure cylinder to be 311.8 H.P.
And in low-pressure cylinder to be . , 331.6 H.P.
Total ' 643.3 H.P.
Work done in low-pressure cvllnder below atmospheric line 186.1 horse-
C»wer. Simultaneouslv with the engine, the pump and fan engines were
dlcated. Tower used was Barnard Type of Cooling Tower.
The work done by the pump 13.75 H.P.
The work done by the fan engines 13.5 H.P.
Total external work 27^H.P.
23.6 1.H.P. of Engine per I.H.P. of Pump and Fans.
1448 GAS.
Nearly all oomm«reially Bucceasf ul sas engines are those in whiA _
ovole of operation ia Uiat proposed anapatented by M. Bean de BodliM,
France in 1808.
He states as necessary to economy with an exploaion engine four eoafr
tious :
1. The greatest possible cylinder rolnme with the leaet possible cool^
surface.
2. The greatest possible rapidity of expansion, or piston speed.
3. The greatest possible expansion : and
4. The greatest possible pressure at the eommenoement of the expsaiios.
JEYom the above JBean de Bochas reasoned these operations :
CK. Suction durinff an entire outstroke of the piston.
b. Compression during the following instroke.
c. Iffnition at the dead point and expansion daring the third rtrokt.
d. Foroinff out of the burned gases from the cyunder on the fooHh
and last return stroke.
He proposed to accomplish ignition by incresse of temperature due la
compression.
The otto engine uses the above cycle and flame ignition.
Claaalilcatloa.
Gas engines may be dassiiied in accordance with the prineiplsB of tks
cycle cf operations:
1. Kxplosion of gases without compression.
2. Explosion of gases with compression.
3. Oombustion of gases with compression.
4. Atmospheric motors.
According to the gas used they may be classified thus :—
A. Coal gas.
B. Carburetted gas.
C. Producer or uowson gas.
The methods of igniting the charge are
/. Electrical arc.
a. Flune.
c. Incandescence,
m. Chemical or catalytic action.
The Otto engine is a good example of flame ignition.
Diameter of gas mam from meter to engine should be dla= j087 Bnks
H.P. +0.79 inches.
Atmospheric air is the working fluid of all gas engines and the fuel wiii^
heats it is inflammable gas.
The air and gas are mixed thoroughly before passing into the eyllndtr
itseU.
{More wasteful of fuel than four-cycle engine. Back-
firing, or premature explosion of gma and air nix-
ture. Used in Urge power units, iHth blast foiaset
gas.
" H oie readily governed than two cycle.
No pumps.
No indosed crank chambers.
Must be built heavy in comparison with power pro>
duced.
^ Heavy flywheelB.
There Is but little difference between gas and nsoUne engines, the mahi
difference being a special fitting to supply the oilin the form of a vapor or
atomixed spray. , , ^ ^ ^ .
Gasoline being richer than gas, by Its use a much larger H.P. can be ob-
tained from a given size of engine.
The theoretical eiHclency of a gas engine is about three times greater tfasa
that of a steam engine.
Contrary to steam engine experience, when underloaded it is a compsiar
tively efficient heat enyne. ^^_
• W. W. Christie.
Four-cycle engine. -
GAS ENGINES. 1449
Tlie htl^ett recorded effloiency is the ooxasmnptloii pf 8000 B.T.U.'s per
Brake IIJP.» or a thermal effloiencv of 81.75 per cent. GoToming Is not quite
as easily aooompllBhed under ooickly Taryingr loads, as in tbe steam englnei
althonsA late modelB leave little to be deeired.
In general, govemiue is accomplished by three methods : (1) the hit-and-
miss, wbere the gas Talve is closed during one or more revolutions of the
engine : (2) by varying the mixture of air and gas In the ovlinder, thereby
producing explosions of greater or less pressure intensity ; (3) advancing or
retarding the point of ignition.
The aTorage mixture is 1 part of gas to A parts of air in a gas engine.
Qas engines can be run successf uUv and with a fair degree of economy to
witbin 3 or 4 per cent of their normal rating.
B. A. Thwaite says the ** lean gases of lov calorific power, such as are
obtiiinable as a by-product of the manufacture of iron, are tne very ones
whicb enable the highest efficiency to be secured in internal-combustion
engines.'*
A gas rich in thermal units enables a larger power to be derived from a
given engine than can be obtained by the use of a lean ras.
IjesB sir is required to mix with lean gas, and a higher compression is
reached, for the mixture has a higher iflxiition point than rich gas mixtures.
Hlgb compression conduces to hieh emciency.
Compression varies inversely as the calorific viJue of the gas, high for a
lean gas, and vice-versa.
For natural gas the compression displacement is made about 30 per cent
of piston displacement.
water for cylinder jacket should flow through at a rate of 4 to 6 gallons
fer H.P. per hour ; best conditions are when Jacket water removes 4000
i.T.TJ. per H.P. per ^our.
Beet piston speed Is about OIKK per minute.
Comparative Ecoaomy.
libs, of Coal
per Brake
H.P. per
Annum.
Steam engine plant— simple non-condensing
BtiMun engine plant — compound condensing
Gas engine plant with producer gas . . .
11,250
6,400
3,060
Per Cent.
Thermal efficiency simple non*condensing plant 6.6
Thermal efficiency compound condensing plant 9.7
Thermal efficiency gas engine plant usli^ producer gas . . 20.3
Thermal efficiency gas engine plant using waste blast fur-
nace gas 23 JS
The standard gas is the natural gas of western Pennsylvania, whose Mlo-
riflc value is about 1000 B.T.U.'s per cubic foot.
Ordinary illuminating gas has 760 B.T.U*s. per cubic foot.
Producer gas may be as low as 120-130 B.T.U.'s per cubic foot.
GousumptTon of gas or gasoline by engines is, conservatively:
Natural gas 10-12 cu. ft. per Br. H J^. hour.
Illuminating gas 18-20 cu. ft. per Br. H.P. hour.
Commercial 'A*' gasoline . . i-4 gallon per H.P. hour.
Gas engines operate on, Bay,l^ lbs. of good anthracite or bituminous coal,
approximately, in some cases as low as I lb. anthracite or bituminous coal.
Oas generated from wood in Riche's retort, according to James M. Neil,
has a caloriflcpower of 3029 calories per cubic meter, or :
340.8 B-TU. per cubic foot ) , ^ ^ - ^^ „^
324.6 B.T.U. per cubic foot j " ^^^^ ^^^ ^^^^ «**•
•600.0 B.T.U. per cubic foot is given for coal gas.
1 ton of wood produces 26,000 cu. f i. of gas and 400 lbs. charcoal, and costs
14 cents per 1000 cu. ft. with wood at 93.00 a ton, negleoting in this calotila-
tion the charcoal.
1450
OAS.
Mr. T. FalrlT, Leeds, England, jeItm tlie heftting power of eoel ca
■ponding tO lignting powers as follows: no correction being maoe for tlM
oondeneation of the steam produced by the eombnstiQn of hydrogen.
Lighting power : —
O.P. 11 12 13 14 15 16 17 18
B.T.U. 633 666 678 001 824 618 €78 TDi
Valve mt Geal C^ae
EetlTe Po«r«r.
n tmr
(C. Hunt.)
Gonsnmption
ReUtiTe Value
BelaUTe Valae
Candle Power.
Cable Feet per
for Motive
for
LH.P.
Power.
Lighting.
11.96
30.31
1.000
IjOOD
16.00
24.41
1.241
IJM
17.20
22.70
1.336
1.438
22.86
17.73
1.700
1.910
26XX)
16.26
1.864
2.173
28.14
16.00
2.020
2.436
Oaa BBgiae Pawer Pteat.
Lackawanna Steel Co., Buffalo, N.T., uses Blast Furnace Qi
8-1000 H.P. Gas Engines in place, 1803. 16-2000 U J". Qas Engines to go is
later.
Electric Generating plant consists of :
6-600 K.W. 3 phase, 26 cycle, 440 volt machines. (Gen. Eleo. Co.)
4-600 K.W. 2d0 Tolt, direct current machines. (Spragne.)
Eight of the above are direct connected to horixontal, duplex, 2 cycls,
double-acting, Korting Gas Engines.
One is direct connected to a 1000 H.P. Porter-Allen steam engine.
Engines use the waste gas from the furnaces.
By volume : CO, 24% ; CO,, 12% : N, 60% ; H, 2% : CB[«, 2%.
Calorific Power, 90 B.T.U.'s per cubic foot.
The steam boilers in thU plant are 260 HJ». YerUcal CahaU Boilers ; «
have Boney Stokers, others are gas fired.
They eacn have a two-part cylindrical monitor on the roof of the boflir
house, that is easily removed, enabling rapid and easy cleaning of tabes.
»• Power," Dec., 1908.
CUm Baglae Paaspla^ Plaat Vest.
MldTale« If .X. Triplex pump driven bv a 6 HJP. gasoline eKiae,
7th trial. Discharge 163 gallons per minute. Lift, 66 ft. total. Used6f gil-
lons of gasoline or 0.312 gallons per H.P. hour.
Oreeaabargr, Mad. Triplex pump driven by a 6 H.P. crude oil engis*
(Indianapolis, Ind., Eng. Co.), 9th trial. Discharge 184 gallons per minatt,
total lift 81.3 feet. Montpelter Crude Oil, 2 cents a gallon --0.47 gallons per
H.P.hoar. (Eng. Bee. V: 38, 606.)
Cast af IJfUagr floater.
With gas at 82^ cents per 1000 ft. One H.P. for 3000 hours, with a gas flD>
glue at,—
Wilraerding, Pa 88418
Pitcaim,Pa 10.88
E. Pittsburgh Pa 12.70— 4 load on during tert.
(Eng. Bee. y. 38, 99?.)
The Haat Maaiij from burning gas Is disposed or In the Otto gis
engine as follows :
STEAM TURBINES. 1451
Armrmg^m of Mmnj Teste.
1. Actual work and friction 17 per cent.
2. Hot expelled gases 16^ per cent.
3. Water Jacket 62 per cent.
4. Conduction and radiation 15^ per cent.
mttsborg Plate Glass Co., Ford City, Pa., uses natural gas of 1000
B.X.U.'s, obtained on the premises.
pumping unit of six units (5 now in —1903) consists of :
One 11" X 12^' — 3 otI. Westinghouse Vertical Gas Engine direct
Seared toalO'' x IS" single acting triplex pump, Stillwell-Bierce
i Smith-Valle Ck>.
Compressed air is used to start the engines, beins tanked in 3 steel
storage tanks for this purpose. A 3 B.P. electric motor sup-
plies this air at 180 lbs. pressure.
Total head pumped against, 215 ft.
Gallons per minute, 1101.
TTotal cost per million gallons. $7.02.
Steam plant doing same work cost $1,700 per month (average) for
fuel alone.
GtkB method cost $180 per month for fuel alone.
Pall teat and diagram of engine efficiency in *' Power,*' Dec., 1903, p. 706.
Steam turbines, machines in which Jets of steam striking yanes or bueketo
at a high Telocity, are used as a motive power, may be classified thus :
l.E«Ualflow . . . .{?„"4:^-
f De LavaU
2. Parallel or axial flow i ^^^1^'
t Curtis.*
3. Mixed flow.
If steam at a high pressure be allowed to escape through a suitably de-
signed diTerging nozzle into a lower pressure, a large proportion of its heat
eneivy will be converted into kinetic energy, and the steam will expand
adiabatically to the pressure of the medium or fluid into which it is discharged.
There is a wide difference between steam turbines and water turbines, for
tbe nozzle velocity of steam is, say, 2,000 feet per second against 0$ feet for
-water.
Then again, 1 cubic foot of water gives the same amount of kinetic energy-
as 1 cubic foot of steam at 60 lbs. pressure.
The efficiencies of all types depend very largely upon the terminal press-
ure at the exhaust end, and likewise on the completeness of the vacuum,
where condensers are used ; which accords with reciprocating steam-engine
practice.
The absence of lubrication in the internal or steam spaces, permits the use
of condensation and return of all water of condensation to the boilers.
Both the above factors, as well as the use of superheated steam, assist in
seenring the high efficiencies already obtained with this motor.
Experience shows that water carried over from the boiler does no harm in
them.
One point which is made In their favor, is, no boiler scale when the same
feed water is used continuously. In that event, boilers may suffer even more
seriously from corrosion from the water being too pure, unless raw water is
added from time to time to neutralize the corrosive tendency.
The steam turbine has opened up a field of usefulness all its own ; for ex-
• W. W. Christie.
tloe grt&t efflcieboj wu only dMaIdm
.--- inceHlMprM
^, ,___, .^ , . lov haadi, tarbloe oAdiaiej i
malntalDed STen at rery grakt hud. Wblln used miMO la ditra fuw, pnk
■bl; thegrMUaCHeldopentoalAuntnTblnnii UiedrlTiiv<>I<dactiic|Bv
atOTi, dlnoUMimsoted oi dlrsot^ceamd.
£d thU type the total poT«r ol
TelooltT In ta exMUidliw nouls.
The jot lo produced & drlTsn a^Det
It la llmllsd oalv by MMndlng liiiperf«tioi
eapeolallT ■ppllnbl* to Urn aUM ; tb<y are
thui 1001I.P.
At now dMigiMd, tb
Id gMTlOf , Mid
It at prevent bdJ
way to raren* tUi nutBhlne.
[I^^kf
» of >uperbe*(«d atsam
IuUm.
but.
Load
irlth
IS
Load
with
SatQ-
rat«l
8t«am.
StMin
Brake Kp.
DryS(«uo
steam.
Eight
Saisn
84
M
H.P.
Si
H.P.
Lba.
ISM
Lba.
%
U
Other testa by the aame sngineere gare wf th aupertwated it
BTEAM TUaBlNES.
hiIh Ohu, Eigbt IS).
. ^ lug ot Buomaiar, ai.18 In.
^▼•ragB Tsmpenture at ttoom, S9° F.
i
1
1
K
£ -*
i
a
1
^ 1
"^i"
a.
i
4341
SD8.3
207.S
208.9
J7.a
Si
i
3H.6
3&4.t
»^
M4.4
13.SS
In the Partona tnrblna tha ■team, >f t«r lesTlag Iha goTsmor TalTB, snten
• Bt«wii paua^ itnd tama to [be right. DrBl piuing ■ ■(ktlanu-j let of blade*,
tbsn tbe bUdeeot a ravolrlng a jUnder ; tbd operatloD Ji repeated a number
Of ttmea, the ateun moilng In ou ulal direction until It ha* nulled tbe
MoviHa
nXED
fie. IB. Van**, VaatlnghoaHt-ParHO* Tublns.
Other end of the turbine, «
peratare a* 118° F.
Tbe ■team Talooltr <■ not
in It li eihanated, lomt
Land boriiontal
Dat in (Ua type a* It 1
■paoe occupied bj II
iteam anglnae.
i.^ '"
c^9 OJS
\
\
sj
7^
■">■— J
6TEAH TURBINES.
Tjp9.
Bow. of
BSt
s&
pwSMond.
BtuklM.
Batsau '.
S^^: :
»
i
2:400
1, 800
400
MO
i;!oo
a"-
Inaerted
iwhitt rsilueed ^
impKBhed by regulating tha flteun iti
iiuDiDptlon or 14.47 tuU luad
itlDE. All par bnkc H.P.
,_..iid,r800K.W.,lSSll».itBi .
n. 4fiBP. auparhatii.gaveia.l Dm. of ateun par K.
11.46 perl. H.P. hour.
A 400 K.W. Turbine BSTa
at bBU rntlng, IS lb*. iS ont
The tnrblna At Hurtford. aierase low
27 inoh Ttaunm. 4fi°P. auDorhast. oiiVi
oqtua - -'--- ■*" " -
!^To"
CarMa •«•«■• *>■■»>(>,
In the Curtia St«km Turbine (be taloolty la gitea to the Meun
Aipuidtiig noule, dealgned ao u to oaarert nearly all of the •!
•xpaalTe force iDto Toloolty in IMelf.
Leavtug Ibe nonle the at
the fixed elamant.
plBced alternately, wicb rararaed TBDea, on
1466 STEAU.
a<t<rBniliu I* effected br cloiliu or opeiiiiis tome of the :
thai urrowliw or wUealu Che sMun belt.
^eedrogiilkttaa !■ 2 to 4%.
BerolDUane per mLnale of 800 K.W. muUne U UOO.
Velocity o( ateua lekTldg the Jet I* MOO ft, per saexnd.
CompMM with Urge eoclne outHU tn MuibMlBB BkUwi
NewToAPoirerPlBul— theirilghtioiaiirtUli tgwelchtol
no. as.
The ooDdenetog trpe !■ maiMj dealgned for UO lbs. Esuge tU$a pn«»
mnd s VMDUmofSS Inchea of menmry at aea lelel.
Under thau conditions normal OTerload may be 100%.
Tbli tTp« la nov being built with a oondenasr in tu biae.therttr'*'^
fewer Jdnte and coaneotlalu kDd > better TMnnm, reeultlDg l> • il*"
Increaie In the height of the machine. ._
A Tsrtlcal ghaft and alep bearing are tjplcal of the Cunt X™**
STEAM TURBINES.
I>n«r mlMtt, and Uum^li htina labricatsd with oil, exparfnieiila an
MJDK oBirled out, lunug In Tlair the lua of water lu plua ot the
I amUiim m*dlain, then itaun puking of ■tam will be sTolded, lu
dl b« used In oondeiuer proper.
This t&bl* glTM (ome Idea of (he proportlomi of the Unrtls Tiublna
■ taken trom a paper b; A. H. Kmeil.
b5?!m:
Stag.,.
1
s
B,O00
ao
Hon>»ntal
soo
NO
3,100
i
lis
UB
ISO
li
BOO
AJ.TBKH
ATIHOCD
SBBHT » OVC
U.
3
lOO
3,600
WOO
Horliontal
'*
"
The Ratean trpe !■ ■oiaewhat simitar
DmblnfttToDi of nOKilee and hIo^ wheal
than In (he older (nrblnas.
>f noKilee uul all
opaailan than In (he older (oi
In mAhlne comparUouB with other
ling coiDparUoDB i
rbine», ifie ararag
h 02 lb*., ualna( 429 (or gaj
A.bont (he ums ratio, or
_'..'^
II
9 =1^
M S-3
It a|1
i
ill
IIS
lit
U:
°<
In
luseie -wn 0001 -r-^-.,-.---,--.,-^ —
gS|fESSggSS58SXaSg3S|
^|::SSii$^S = S^8S»^99^^Z8;E!
ll§S§§SS§SSS§SBSSBsSt!S'
^S3^SS^^^SSqS!1JtS!;3!;^^8ei
§SBSSSs33S33SSS§s§S3S|E
«;^3;e8^!S:^3;^^8.i;S58a^S»»'
sssssgssssssaxRS&sssseas.
iHTOIB 'igq 0001 1
eiSSSSISSSS3SgS8|SS§S|S=
iJO'DT
w -r -^ ■* ■« «■ * * -v -«"* -^ w V -T -* •* e u a oe I
SeSSSSS!:SiSSI:SS8saSZS3&!
i98n»inB JO ar
;s;:HS!;s^!;^^^^E^;:EEs3siS|:
97$$!;33SSSSS8S&338£88ie
saxs383S^3^^s^i^see^s^i:S|
8S»S3»8S:SASSIJi;S8«RSilS;SI
STEAM TABLE. 1459
A handy mle for approximately determining the outflow of the steam is
lae following :
If the abeolnte steam pressure at the inlet end of the orifice is p at-
Mapberos ^ kg. steam win flow through eaeh mm.* of the smallest section
roa of the oilflce per hour.
The ahorre company hare in many trials demonstrated this to be true
rtthin fire per oeni.
1460 WATER-POWER,
WATBIUPO W JfiK.
Is detarminlng the feasibility of ntillsiBg water-power to operate (
eally the indvetnes of any particolar town or city, careful
miut be given to the following points, tIs. : 1. The amount of
permanently aTallable. 3. Tne eost of developing thie power. X
terest on this amount. 4. The total demand lor power. 6. The i
and relative locations of the various kinds of power. & The ooet of l
plants now in operation. 7. The interest on this amount. 8. Cost of
for plants now in operation. 9. Cost of operating present plmnts. liiherj
10. Cost of maintenance of present plants. 11. The amocmts and k&ite
eleotiio power already in operation. 12. The distance of ti
13. The estimated cost of the hydraolie machinery. 14. The
efficiency and regulation of the hydraulic machinery. 15. Kitttmatinl '
electric machinery. 16. Estimated cost of line eonstenetloii. 17. Total <
of operating hydraulic and electric machinerv. 18. Total cost of bm
nance of hydraulic and electric plants. 19. Tne Interest on tlie totsl
mated cost of proposed plant. 20. The estimated gross income.
Charles T. Main makes the following general statements as to thsviii
of a water-power : " The value of an undeveloped variable power Is
nothing if its variation is great, unless it is to oe supplemented by a
" ttie^
plant. It is of value then only when the cost per horse-power tar i
plant Is less than the cost of steam^wer under the same oondilioH
mentioned for a permanent power, and its value can be repreeented in
same manner as the value of a permanent power has been repreeented.
" The value of a developed power is as follows : If the power eaa be
cheaper than steam, the value is that of the power, plus tlie ooet of
less depreciation. If it cannot be run as cheaply as steam, oonsidec^
cost, etc., the value of the power itself Is nothing. t>ut the Talae of the l
is such as could be paid for it new, which woula bring the total eost of
ning down to the cost of steam-power, less depredation.**
Mr. Samuel Webber. Iron Age, Feb. and March, 1893, eritieiees the
ments of Mr. Main and others who have made comparisons of eoeta of i
and of water-power unfavorable to the latter. He says : ** Tliey have 1
their calculations on the coat of steam, on large compound engines of
or more h. p. and 190 pounds pressure of steam m their boilers, and by c
ful 10-hour trials succeeded in figuring down steam to a eost of abootj
per h. p., ignoring the weU-known fact that its average ooet In praotieal
except near the coal mines, is from $40 to fSO. In many Instances di
canals, and modem turbines can be all completed at a cost of $100 per h. p.;
and the Interest on that, and the cost of attendance and oU, will hmg
water-power up to but about 910 or $12 per annum ; and with a man
tent to attend the dynamo in attendance, it can probably beaafely «
at not over $16 per h. p.
Xiocation.
Oeographlcal, ete.
Sketch of river and its tributaries.
Surrounding countrv and physical features.
Sources ; lakes, springs, etc.
Water's head: area drained, nature of, whether forest,
covered mountains, etc.
Elevation of head waters and of mouth.
Length from main source to mouth.
AccessibUity ; how and by what routes.
Reports of U. 8. Coast or G^logical Survey.
Reports of Engineers U. S. Army.
Any other reports.
Any estimate by engineers and for what purpose.
When it ilrst attracted attention and for what reason.
History.
REPORT ON WATER-POWER PROPERTY. 1461
iS?lSrSffbrj^r.^w'?;>' Of w.U«h«I = », ^ »« ^ of total nUnOU
<k>inparlsaii vith other rlyen.
Possibility of Btoring water for dry time.
Av»U»l»l« Fall.
Xjoeatlon of; aoceMlbllity, by what routes.
Can power be used locally, or would it be necessary to transmit It, and M
», wliere to, and distances? Katnre of country over which it would have to
le carried.
Volume of water in cubic feet per second.
H^Tse-Power of Itlver*
Galcnlated from available fall and volume.
Horse-power for each fall or dam.
I#ocation of dams, dimensions, length, and height, best method of con-
itruction, estimated cost.
.^Backwater ; volume, and how far ; what interests disturbed by it ; benefits.
ff any. ' ' *'«»«*wi
Compare power with that of similar rivers.
Probable cost of power at dams and transmitted.
Applications Poasiblo.
^ear by ; at distance, stating when and for what Note industries appli-
oablo to ; comparison with other applications.
How Xndostvlos 9aCT:os«od,
and old Industries already going to which power is applicable.
Cost to these, and comparison with cost of other forms of power already
In use. '
.Property of tlio Coaipaay.
lisnd, bundinRs, water rights, flowage rights, franchises, lines, rights of
way. Character of deeds. Probable vidtie.
Comparison with other similar properties.
Other resources.
Uabilitios.
Stocks, bonds, floating debt, other.
Bamingr Capacity.
Probable cost of power per h. p. at power-bouse.
Probable cost of power per h. p. delivered or transmitted.
Price for which it can be sold at power-house, and price transmitted or
delivered.
Surrounding country, its characteristics, people, cities, and towns, Indus-
tries, condition of finances.
Facilities for transportation, water and rail.
Nearness of sources of supplies and sales of products.
Horso-Powor of a 1¥at«rfa11.
The horse-power of a waterfall is expressed in the following formula :
0= quantity of water in cubic feet flowing over the fall In 1 minute.
J7=s total head in feet, i.e., the distance between the surface of the water at
the top of the fall, and that at its foot. In a water-power the head is
the distance between the surface of the water In the head-race, and that
of the water in the tail-race.
r
1462 WATER-POWER.
w = weight of water per oubio foot s= 08J8 Ibe. at 60^ F.
OroM honfr-power of waterfaU = ^^^^[^^ mmrnQK
LoM of head at the entrance to and exit from a water-wh6el«ton(kcritt
the friction of the water passinff through, reduces the power that oi It
developed to about 70 per cent ox the grow power of the mIL
i**wer •f m lft«mMiai«r fttiwuM.
The power is calculated by the same formula ae for a fall, bat Is tlMB
J7=: theoretical head due to the Telooity of the water hi the Unas
V = velooitT of water In feet per eeoond.
Q = the cubic feet of water actually impinging agaiiiit th« bidnl |i
minnte.
Qroee hone>power = .0018B QB.
Wheels for use in the current of a stream realise only about .4of tb*|M
theoretical power.
Current motors are often dereloped to operate in strong enrmti,iasi|
that of the Niagara River opposite Buffalo, but are of little no «o«H
for small powers. Such a small fraction of the current vetoettycisfc
made use of that a current motor is extremely inefficient. Is ow^
realize power from a current it is necessary to reduce Its velocity li Ml
the power, and to get the full power would necessitate the baddiiKiipa"'
whole stream until the actual nead equaled the theoretical.
P«wer of irator FlowlMgr la m Plp«.
iTdue to Telocity = ^ = g^-^ where v = velocity in feet perieoflsl
Hi due to pressures: — , where/= pressure in lbs. per squafe foot
and w = 62.36 lbs. = weight 1 cubic foot of wstff.
H^ distance above datum line in feet.
TotalJSr= p^-t^Bt.
In hydraulic transmission the work or energy of agtvenqiisntltf ofvii'
under pressure is the volume in cubio feet x Ids. pressure per iqiivenA
?=
r= cubic feet per second.
pressure in lbs. per square iaeh.
Horse-power = ^^^ xsSeiBPQ.
Mill.
It has been eustomary in the past to lease vi^terf^ywJ^J^jSS
than the horse-power, and the term nUll-pawer has been ofea w jjg^
the unit. The term has no uniform value, but is diiferent is ^j^^
Emerson gives the following values for the seven more imponiv
Bolioke, Mat. — Each mill-power at the respective f slls Ii dedand to^
the right durins 16 hours in a day to draw 38 cubic feet of *^**2^
at the upper faU when the head there is 20 feet, or a qusntitfFC^
to the height at the falls. This Is equal to 86.2 horse-poirer » «
JLotce//, A/oM.— The right to draw during 15 hours in ^^°%^]
water as shall give a power equal to 26 cubio feet a second s^ ^* *^
when the fall tnere is 90 feet. Equal to 86 h. p. mazimum. . ^gi
Latortnce, Maa$, — The right to draw durinc 16 hours ™ J^i7^«t
water as shall give a horse-power equal to 30 enbio feet per t^^^^
head is 25 feet. Equal to 86 h. p. maximum. . ^^ ^ I
Minneapolii, Aftnn.— 30 cubio feet of water per second wlin "^
feet. Equal to 74.8 h. p.
MERCURY AND WATER.
1463
Mamche^ter, N, H. — Divide 726 by the number of feet of fall mixiiu 1. and
m quotient will be the number of cubic feet per second in thtut fall. For 20
et fall thia equals 38.1 cubic feet, equal to 86.4 h. p. maximum.
Ofkoe*^ a. Y, — " Mill-power " equivalent to the power given by 6 cubic
•C per second^ when the fall is 'JO feet. Equal to 13.6 h. p. maximum.
PoMscUc, N. •/.—Mill-power : The right to draw 8| cubic feet of water per
loond, fall of 22 feet, equal to 21.2 horse-power. Maximum rental, ^700 per
lar for each mill-power = $33.00 per h. p.
The horse-power maximum above given is that due theoretically to the
a;ht of water and the height of the fall, assuming the water-wheel to have
eet eflloienoy. It should be multiplied by the efdciency of the wheel,
175 per cent lor good turbines, to obtain the h.p. delivered by the wheel.
t Niagara power has in all oases been sold by the horse-power delivered
> the wheels If of water, and to the building-line if electrical.
Charges for water in Manchester, Lowell, and Lawrence, are as follows :
About fdOO per year per mill-power for original purchases.
|2 per day per mill-power for surplus.
About fSOO per year per mill-power for original purchases.
ttper day per mill-power during ** back-water.'^
fiper day per mill-power for surplus under 40 per cent.
910 per day per mill-power for surplus over 40 per cent and under 60 per cent.
M> per day per mill-power for surplus over 50 per cent.
#75 per day per mill-power for any excess over limitation.
About 9300 per year per mill-power for original purchases.
About 91200 per year per mill-power for new leases at present.
94 per day per mill-power fur surplus up to 20 per cent.
96 per day per mill-power for surplus over 20 and under 60 per cent.
94 per day per mill-power for surplus under 60 per cent.
JDHPAJRIflOlf OV COM.iniI]VS OC W^ATKS IM FBET,
lerca
rr ta Incliea,
»B« JP
^rcMvre la MJI^m,^ p«i
■ 0qiiar« f neb.
Lbs.
Water. Merc'ry
Water.
Merc'ry
Lbs.
Merc'ry
Water.
Lbs.
Press.
Press.
Press.
q.In.
Feet.
Inches.
Feet.
Inches.
Sq. In.
Inches.
Feet.
Sq. In.
1
2.311
2sm
1
0.8863
0.4327
1
1.1296
0.4887
2
4.623
Axm
2
1.7706
0.8654
2
2.2690
04>776
8
6.933
6.138
3
2.6660
1.2981
3
3Jffi86
1.4662
4
9.244
8.184
4
3.6413
1.7306
4
4,6181
1.9560
5
11JS65
10.230
6
4.4266
2.1635
5
6.6476
2.4437
6
13.866
12.2276
6
5.3120
2.5962
6
6.7771
2.9325
7
16.177
14.322
7
6.1973
3.0289
7
7.9066
3.4212
8
18.488
16.368
8
7.0626
3.4616
8
9.0361
3.9100
0
20.800
18.414
9
iJdeea
3.8942
9
10.165
4.3987
10
23.111
20.462
10
8.8633
4.3273
10
11.295
4.8875
11
26.422
22JM)8
11
9.7386
4.7600
11
12.424
5.3762
12
27.733
24iS64
12
10.624
5.1927
12
13.654
5.8650
13
30J>44
26.600
13
11.509
5.6265
13
14.683
6.3637
14
32.166
28.646
14
12.384
6.0562
14
15.813
6.8425
15
84.666
30.692
16
13.280
6.4909
16
16.9*2
7.3312
10
86.977
32.738
16
14.165
6.9236
16
18.072
7.8200
17
30.288
34.784
17
15.060
7.3663
17
19.201
8J087
18
41JS09
36.830
18
15.936
7.7890
18
20.331
8.7976
19
434)10
38.876
19
16.821
8.2217
19
21.460
9.2862
20
46.221
40.922
20
17.706
8.6544
20
22JS90
9.7760
21
48.632
42.968
21
18JS91
9.0671
21
23.719
10.264
22
60.843
46j014
22
19.477
9JS196
22
24,849
10.752
23
63.164
47X)60
28
20.362
9.9625
23
25.978
11.241
24
66.465
49.106
24
21.247
10.385
24
27.108
11.7800
26
57.776
61.162
25
22.133
10.818
25
28.237
12.219
26
00X)87
63.198
26
23.018
11.251
26
29.367
12.707
27
62J»6
66.244
27
23.903
11.683
27
30.496
13.196
28
64.700
67.290
28
24.789
12116
28
31.626
13.686
30
67j020
69.836
29
26.674
12.549
29
32.755
14.n4
30
69331
61.386 1 30
26i;60
12.961
30
33.885
14.662
I
^ 1
I
i I
i a
n
t i
PKESSURE or WATER.
1465
•VliB 0«
are of water in pounds per square inch for erery foot in height
> aOO feet ; and then by interralfl to 1000 feet head.
Feet
JPrees.,
Feet
Press.,
Feet
Press.,
Feet
Press.,
Feet
Press.,
[e'd.
Sq. In.
Ue*d.
Sq. In.
He'd.
Sq. In.
Head.
Sq. In.
Head.
Sq. In.
1
0.43
66
28.16
129
66.88
193
83.60
257
11152
S
0.86
66
28.68
130
66.31
194
84.03
268
111.76
s
ijn
67
29.02
131
66.74
106
81.47
259
112.19
4
1.78
68
29.46
132
67.18
196
84 JO
260
112.62
&
2.16
69
28.88
133
67.61
197
85.33
261
113.06
6
2.68
70
80.32
134
68.04
198
85.76
262
113.49
7
3.03
71
30.76
136
66.48
198
86.20
263
113.92
8
.3.46
72
31.18
136
68.91
200
86.63
264
114.36
9
8.86
73
31.02
137
69.34
201
87.07
265
114.79
lO
4.38
74
32.06
138
69.77
202
8750
266
116.22
11
4.76
76
32.48
139
60.21
203
87.93
267
116.66
13
6.20
76
32.92
140
60.64
204
8856
268
116.09
13
6.63
77
33.36
141
61.07
2U6
88.80
269
11652
14
6.06
78
33.78
142
6151
206
89.23
270
116.96
15
6.49
79
84.21
143
61.94
207
89.66
271
11759
16
6.98
80
84.66
144
62.37
208
90.10
272
117.82
W
7.36
81
86.08
146
62.81
209
9053
273
118.26
18
7.79
82
36JS2
146
63.24
210
90.96
274
118.69
19
8.22
88
86.96
147
63.67
211
91.39
276
119.12
20
8.66
84
38.30
148
64.10
212
91.88
276
11956
21
9.09
86
8682
149
6454
213
92.26
277
119.99
22
9.68
66
37426
160
64.97
214
92.69
278
120.42
23
9.96
87
87.68
161
66.40
216
93.13
279
120.86
24
10.39
88
88.12
162
66.84
216
9356
280
121.29
25
10.88
89
88J«S
163
66.27
217
93.99
281
121.72
26
11.26
90
Sojm
164
66.70
218
94.43
282
122.16
27
11.69
91
39.42
166
67.14
219
9456
283
12259
28
12.12
92
89.86
166
6757
220
9550
284
128.02
S9
12.66
96
40.28
167
68.00
221
95.73
286
123.45
80
12.99
94
40.72
168
68.43
222
96.16
286
123.89
SI
13.42
06
41.16
169
68.87
223
96.60
287
124.32
82
IdiW
96
41J»
160
69.31
224
97.03
288
J24.75
33
14.29
97
42.01
161
69.74
226
97.46
289
125.18
84
14.72
96
42.46
162
70.17
226
97.90
200
126.62
85
16.16
99
42.88
168
70.61
227
9853
291
126.06
86
15.69
100
43.31
164
71.04
228
98.76
292
126.48
87
16.02
101
43.76
166
71.47
229
99.20
293
126.92
38
16.46
102
44.18
166
71.91
230
99.63
294
12756
89
16.80
106
44.61
167
72.34
281
100.06
296
127.78
40
17.32
104
46.06
168
72.77
282
100.49
296
128.22
41
17.76
106
46.48
160
78.20
233
100.93
297
128.66
42
18.19
106
46.91
170
78.64
234
101.86
298
129.08
43
18.62
107
46.84
171
74.07
236
101.79
299 .
12951
44
19.06
108
46.78
172
74.60
236
102.28
800
129.96
46
19.49
109
47.21
173
74.94
237
102.66
310
134.28
46
19.99
110
47.64
174
76.37
238
103.09
320
138.62
47
20.36
111
48.98
176
76.80
239
10353
830
142.95
48
20.79
112
4851
176
76.23
240
108.90
340
147.28
40
21.22
118
484M
m
76.67
241
104.39
360
161.61
60
21.66
114
49.38
178
77.10
242
104.83
360
16654
61
22.09
116
49.81
179
7758
248
106.20
370
160.27
G2
29 JU
116
60.24
180
77.97
244
105.69
380
164.61
68
22U»
117
60.68
181
78.40
246
106.13
390
168.94
64
28.89
118
61.11
182
78.84
246
10656
400
173.27
66
23J82
119
6154
188
79.27
247
106.99
600
21658
A
66
24.26
120
61.98
184
79.70
248
107.43
60O
269.90
.A
67
24.69
121
62.41
186
80.14
249
107.86
700
803.22
li
66
25.12
122
62.84
186
8057
260
108.29
800
34654
■
66
25Jf6
128
63.28
187
81.00
261
108.73
900
889.86
^
60
26J)9
121
53.71
188
81.43
262
109.16
1000
433.18
^
61
26.42
126
64.16
189
81.87
253
10959
62
26.66
126
64.68
190
82.30
254
110.03
e
27.29
127
86.01
191
82.78
265
110.46
84
27.72
128
66.44
192
88.17
256
110.89
1466 WATER-POWER.
Rireted sheet steel pipe is mach used on the Pacific Cosst for .
water for considerable dutances under high heads, say as maeli aa 1700 J
Corrosion of iron and steel pipe hae always been an BTgamient mg^imttUt
use, but for about thirty years such pipe has been in uae in Calif anaa;af
a life of twenty-flye years is not oonaidered the limit, when both inside ai
outside of the pipe are treated with a coatlns of asphalt.
The method of covering with asphalt re^rred to affords perfect fnt«>
tlon against corrosion, and so long as the coating Is intact^ makes ft mti^
oally indestructible so far as all ordinary wear is concerned. Tika eoDdiaas
which interfere with the best senrice are where the coating Is worn off If
abrasion in transportation, or where the pipe is subject to soTere theck If
the presence of air, or by a sudden closing of the gates, or wliera tlie aenrias
is intermittent, causing contraction and expansion, whidi omtis the joak
and breaks the covering. With ordinary care theee objections ean luusllj
be overcome. While the primary object of eoatins pipe in this way » to
prevent oxidization, and thus insure its durability, It is incidentally sa ad-
vantage in providing a smooth surface on the inside, which reduces the fiie-
tion ox water in its passage.
The Coast method of laying pipe is to take the shortest practicahle ds*
tance that the ground will pernut, placing the pipe on the sorfaee aa
necting directly from ditch, flume, or other source of supply to the
Avoid short turns or acute angles, as they lessen the head and prodnoe
The ordinary method of loTnting is the §lip Joint, made np in moAtbs
same way as stove-pipe. Or course this is omy adapted to eompantivify
low heads, special riveted-Joint construction being neceuary for *^^^
falls. In laying such pipe where the lengths come together at _^ .
lead Joint shoiud be made. This is done oy putting on a sleeTe, allowa^a
space, say three-eighths of an inch, for running in lead. With a hsMj
pressure, and especially on steep grades, the lengths ehonki be wlrci
together, lugs being put on the sections forming the ioints for this pnmsK
and where the grade Is very steep, the pipe should be securely aBcaand
with wire cable.
In laying the pipe line it is customary to commence at the wheel* ami vi&
slip Joint we lower end of each length should be wrapped with eotton drill-
ing or burlaps to prevent leaking ; care being taken in driving the joiais
together not to move the gate and nozzle from their position. Some taafO'
rary bracing may be necessary to provide against thiB.
where several wheels are to be supplied from one pipe line, a brsaA
from the main in the form of the letter Y is preferable to a right angle 08l>
let. When taken from the main at a right angle, the tap-hole shooMbe
nearly, as large as the main, reducing by taper joint to the size of p^
attacned to the wheel gate.
It is advised where practicable to lay the pipe in a trench, eoveriagli
with earth. Even in warm climates, where thb is not neoessary as protae-
tion from frost, it is desirable to prevent contraction and ezpanuoa by
variations of temperature, as well as to afford security against aeddait
When laid over a rocky surface a covering of straw or manure will proteet
it from the sun, and generally prevent freezing ; as where kept in moties,
water under pressure will stand a great degree of cold wlthoat givleg
trouble in this way. After connections are made, it should be tested befsn
covering to see that the Joints are tight.
Care should be taken when the pipes are first filled to see that the ah if
entirely expelled, the use of air valves being necessary in long lines li^
over undulating surfaces. Care should also oe taken before starting to see
that there are no obstructions In the pipe or connections to wheel, and tkst
there are no leaks to reduce the pressure. Pipe lines of any oansidenhle
length should be graduated as to size, being larger near the top and redoecd
toward the lower end, the thickness of iron for yarious sizes being delar-
mined by the pressure it is to carrv. This is a saving in first cost, aad
facilitates transportation by admitting of length, being run inside of eaek
other.
When used near railroad stations, pipe is generally made in 27 ft. IsBgtts
for purpose of economizing freight, this being the length of a ear. wmb
transported long distances by wagon, it is usually made In about 90 ft.
lengths. For pipe of large diameter, or for trannmrtation over long dis-
tances, as also for mule packing, it is made in seeoons or loints of 91 to M
'nches in length, rolled and punched, with rivets famished to put togefkar
RIVETED STEEL PIPES.
1467
I tli.e gJTOund where laid. Pipe of this character, being oold rlreted, U
i0lly pu^ togetb<^r with the oroinarv tools for the purpose. In such caset
MU'«tt<Hi should be made for coating with asphalt before laying.
weted Bteel pipes have also been extensiyely used in the East In the in.
■llAtion of the new water supply for Newark, Jersey City and Paterson,
•«F., also at Kochester, N.Y., and were furnished by Mr. Tnos. H. Millson,
f Kamt vJersey Pipe Company, Paterson, K.J.
of Itivet SpaclMir* for Clrcalar S«a
Pipes 48" to 6V' Diameter.
■as of ]*ip«.
//
It
«
//
n
//
tt
4»m4»tor of pipe. . .
► •
48
48
48
51
51
51
51
liiclcn^MW . , . r ■
t
i
1
1
t
ft
1
1
1
ft
1
^lamoter of rivets . .
> •
f nn&'ber of rivets .
1 •
100
84
74
106
92
80
64
^ngtlx of long plate .
> ■
151.562
151.779
151.976
162.764
163.354
163.943
164JS32
joMigttk of short plate
■ •
149.806
140.717
148.538
161.007
161.208
161.300
161JS86
■Uvet pitcb on long plate,
1.515
1.807
2.063
\Iffl
1.776
2.049
2JJ71
B iTe t pi tcb on short plate,
1.488
1.782
2.020
1.481
1.752
2.017
X526
L»p, center to edge . . .
1
1ft
1|
1
1ft
1|
1ft
Lap at ctrcnm., seams . .
2
21
2f
2
2|
21
3*
■»ift«ss of RlTet SpaclBCH for I«OBgi«adlaal
Seam
a of Pipe.
Nnm'ber In first row . .
36
29
25
86
29
26
It
22
Narol>er in second row
34
28
24
84
28
24
21
Kninl>er in both rows . .
69
57
It
49
60
II
57
48
It
43
KlTet pitch in both rows .
2.277
2.721
3.125
2.277
2.721
3.126
3JS42
Distanco between rows .
1ft
1ft
1ft
Ift
1ft
1ft
11
iAp, center to edge . . .
41
1ft
IH
»
1ft
lU
1ft
Lap stt longitudinal seam,
3
3*
4
3
3}
4
*l
Tliis formula for the design of riveted steel pipe Is taken from Cassier's
Mag^sharine, 1902 : —
T= for iron, usually 48,000 lbs. per sq. in.
7*= for steel, 62,000 lbs. per sq. in.
P = safe working pressure, per sq. in.
t = thickness of sneet in inches.
R = radius of pipe in inches.
e = factor of safety : 3 to 3J{ for this work.
/= proportional strength of plates after riveting:
Double riveting ... 0.7
Single riveting . , . OJS
1h» Water Power Plant at Puyallup River near Taooma will have a
■teel pipe line 1700 feet long, be|^nliig 48" diameter, reducing to 36'' diam-
eter at the end, built by Rioson Iron Works, San Francisco, Gal.
i
1468 WATER-POWER.
In many oasee mnoh expense may be saved in pipe by ooorcylQf At
water In a flume or difcoh along the hlllBlde, oorenng in thlBvijaliip
part of the di8tan<», then piping It down to the power itationbfaMt
line. This is more espeoiaily applloable to laigephmts, where tl»«Qrt«f
the pipe ii an important Item.
DATA WOVL n^VBUM AITO l^MXCHSS.
To giye a general idea as to the oapaoitr of flumes and dltchei for anf
ing; water, the following data la submittea :
The greatest safe Telocity for a wooden flame is about 7 or 8 feet per n»
For an earth ditch this should not exoeed abont 2 feet per lecoiu. IbGU^
fornia it is the general pracUce tolayaflumeonagradeof aboatiinebtothi
rod, or often 3 inches to the 100 feet, depending on the existing ooixlftfoa.
Assuming a rectangular flume 3 feet wide, running 18 inoliei de^ to
velocity and capacity would be shown as below :
Grade. Y eL in Ft. per See. QoantitTCii. ft IGk
tinch to rod 2.6 702
" «• " 8.7 m
" " " 5.8 1,4a
As the Telocity of a flume or ditch is dwendent largely on its bm lai
character of formation, no more specific data than the above can ^jp*^
It is not safe to run either ditch or flume more than about } or | folL
irooi»Bir.»Avs nopm.
Although wooden-stave pipe has been in use for years on old vster povei
for penstoclLs, etc., it seems to have been given but little study ontu att
years, when it has been used to some extent on the Pacific Gout 'or e»
veying water long distances under heads not much exceeding 300 feeiL^
though the construction of wooden-stave pipe is quite simple, y^ ^°^f£
able skill and care are necessary to make water-ti£ht work. One of »
latest pieces of work employing this type of pipe m the plant of ti« an
Gabriel Los Angeles Transmission, California^ ~ where sereral bum «
wooden-stave pipe, 48 ins. diameter, are used. The pipe is laid nnifwTUB
feet below hydraulic n-ade ; and the wood is of such thickness as to b^^J^
water^oakea, and wiu thus outlast almost any other form of ^'('DetfwiB'
The staves are placed so as to break Joints, the flat sides aredresiedwft
true circle, and the edges to radial planes. The staves are cut off iQWj"
the ends, and the ends slotted, a dght-fltting metallic tongue beugoMi"
make the jcAnt. .
The pipe depends upon steel bands for its strength, and in the cue wen
mentioned they are of round steel rod placed ten inches snsrtiromeiag
to center. Where the pressures vary along the line, bands can sejF"
closer or wider apart to make the necessary strength. Thepitfww**
given round bands over flat ones, on account of their embedding tiM^*^
In the wood better as it swells. They also expose less surface to noi »■
would flat ones of the same stroigth. The ends of the bands we w"^
together through a malleable iron shoe, having an interior *b^^^2^i2
head of the bolt, and an exterior shoulder for the nut, the whole ww^jT
being at right angles to the line of the pipe. Where eurres tf«|Jf ^
sharp, they can easily be made in the wooden pipe ; but for short tonjj:
tionsof steel-riveted pipe of somewhat larger internal diametert&tfw
of the wooden pipe are introduced. The joints between wood am »«■ .
made by a bell on the steel pipe that is iM^r than the on^l^^^f ^'^Jv£
the wooden pipe. After partly fllling the spaoe between bell and vooo
oakum packed hard, for the remainctor use neat Portland cement.
Advantages claimed for this type are that it costs l«Htl^*°Ti^
- " JK- - . ^^^ ^j^^ rugged eomttj
life, and greater
Oomi^ed
carrying capacity of stave pipe is said to be from 10 to 40 % mat, aw »■
difference increases with age as the wooden pipe gets smoother, wn**""
friction of the metal pipe increases to a considerable degree. ._ai.M
As compared with open flumes, the life Is so mueh »'«*•' *"If£2rRi
much lees as to considerably more than counterbalance the first ww-^^
detailed information on wooden-stave pipe, see papers by A. uasv*
September, 1898, Am. Soc. G. £.
RIVETED HTDBAUUC PIPE.
1469
1
(Pelton Water Wheel Co.)
Showing weight, with safe head for Tarious sixee of douhle-riyetedplpe.
I
5!
7
12
12
20
20
20
28
28
28
38
38
38
60
50
60
83
63
63
78
78
78
78
78
96
96
96
96
96
163
163
163
163
1»
176
178
176
176
176
18
18
16
18
16
14
18
16
14
18
16
14
16
14
12
16
14
_12
16
14
12
11
10
16
14
12
11
10
16
14
12
11
10
16
14
12
11
10
201
201
201
201
201
16
14
12
11
10
16
14
12
11
10
16
14
12
11
10
lit
i« * • ■
O A> «e a,
400
350
626
826
600
676
296
487
743
264
419
610
367
660
864
327
761
296
450
687
754
900
209
412
626
687
820
246
377
674
630
753
228
348
630
683
096
211
824
494
643
648
197
302
460
607
606
186
283
432
474
667
9
16
16
26
25
36
36
36
50
60
SO
63
63
63
80
80
80^
100
100
100
100
100
120
120
120
120
120
142
142
142
142
142
170
170
170
170
170
200
200
200
200
200
226
225
226
225
226
265
266
266
266
266
ir
T52
<> ? a ^•^
2
3
ft .
§1
t
13
12
16
20
22
24J
13
16
2U
23}
26
1^
17
23
2?
28
14*
17:
24
26
29
18
18
18
18
18
20
20
20
20
20
22
22
22
22
22
24
24
24
24
M
'26
26
26
26
26
28
28
28
28
^
30
30
30
30
30
36
36
36
36
40
40
40
40
40
42
42
42
42
42
42
42
42
42
I
i
^
9l
254
254
254
254
251
314
314
314
314
344
380
380
880
380
380
462
462
462
462
462
630
630
630
630
630
616
616
615
616
615
706
706
706
706
706
1017
1017
1017
1017
1266
1256
1256
1256
1256
1385
1385
1385
1385
1386
1385
1386
1385
1386
16
14
12
11
10
16
14
12
11
10
16
14
12
11
10
14
12
11
10
8
14
12
11
10
8
14
12
11
10
8
12
11
10
8
7
10
8
7
6
^4
lb"
8
7
6
5 2.-
166
262
386
424
606
148
227
346
380
466
135
206
816
347
416
188
290
318
379
466
175
267
294
352
432
102
247
278
327
400
231
264
304
376
426
11
141
10
166
8
192
7
210
141
174
189
213
260
1^ I • •
-"Si's 8
135
166
180
210
240
270
300
321
363
300
320
320
320
320
400
400
400
400
400
480
480
480
480
480
570
570
570
670
570
670
670
670
670
670
776
776
775
776
776
890
880
890
890
890
1300
1300
1300
1300
1600
160O
1600
1600
1600
1700
1760
1660
1760
1760
1760
1760
1760
1760
18
22^
30
i
39
63
42
47
67i
3U
4l|
46
44
48
64
65
74
68
67
78
88
71
86
97
106
126
74*
91
102
114
133
137
145
177
216
I
1470
WATER-POWBB.
Cable V««t flif ^fTftter »«r mtevto
Oriflce 1 0«vtar«
f^ any ether Hm qf oHJhe, wmUiplw by iU area «» tqmare imeka.
Coble W^mt Tlirovrh am Orifice •f 1. Bnm
laf* Voder Heada Varjlof fireot 1 1« 1<
Theoreti-I
oalDia- ied
ehazse In Ydodh
U
1
2
3
4
6
6
7
8
9
10
11
12
13
14
16
16
17
18
19
20
21
22
23
24
26
26
27
28
29
30
31
32
S3
34
Theoreti-
Theoret-
Theoreti-
Theoret-
cal Dis-
ical
B^
cal Dia-
ical
s^
charge in
CvL.rt,
Yelooity
in Feet
U
charge in
Ou.Pt.
VeloeitT
in Feet
%i
per Min.
per Min.
35
per Min.
per Min.
n
3^
481.2
19.77
2847.6
69
4.73
680.4
36
20.05
2887.2
TO
6.79
833.4
37
20.33
2926.8
71
6.68
962.4
38
20.60
8966.4
72
7.47
1075.8
30
20.87
3004.8
73
8.18
1178.4
40
21.13
3048.2
74
8.84
1273.2
41
21m'W
3081.1
75
9.4S
1360.8
42
21.64
SIVUS
76
10.02
1443.6
43
21.90
3166.4
77
10.67
1521.6
44
22.15
8191.8
78
11.08
1606.0
46
22.40
3227.8
79
11.67
1686.8
46
22.65
8263.6
80
12.06
1734.6
47
22.89
3296.9
81
12.60
1800.6
48
23.14
3333.8
82
12.94
1863.6
40
23.38
8368.4
83
13.37
1924.8
50
23.61
3402JS
84
13.78
1984.2
61
SSAS
3436.4
85
14.18
2041.8
62
24.08
3469.9
86
14.67
2097.6
63
24.31
3603.1
87
14.96
2152.2
54
24.54
8536.0
88
16.31
2206.0
66
M.76
3868.6
80
16.67
2266.6
56
24.99
8600.9
90
16.02
2307.6
67
26.21
3682.9
91
16.37
2367.4
58
26.48
30B4.6
92
16.71
2406.0
60
25.65
8696.1
93
17.04
2453.4
60
26.87
3727.3
94
17.36
2600.2
61
26.06
8758.2
96
17.68
2545.8
62
26.29
8788:9
96
17.99
2500.8
63
njsi
8819.3
•7
18.30
2635.8
64
26.72
9849.6
98
18.60
2679.0
65
26.92
9B79A
99
18.90
2722.2
66
27.13
3909.2
100
19.20
2764.2
67
27.33
30SB.7
19.40
2806.9
68
27JS4
3968.4
per Min.
27.74
S7.94
98.14
28.34
28JS3
28.73
.11
29.49
29.68
80tj06
80^94
a0.i42
30^
30.79
30J97
SIJ6
31 -SS
SIjBO
31.68
31J86
32JM
83J06
S3.2S
33.40
THEORY OP ROD FLOAT OADQINO.
n*w of Water Throack bb OrUce.
The ba*t form of aperturs lor glTins the gruUat flow ol witter ii > ooi
CKl apotors wboc« grtater bue !■ tba aperture, the height or length of tt
'-- -' — e being half (be diameter of aperture, luid the area of ■'
FiAir OF vrA.iMM in a
, which will giye
the total crou-aectlOQ
FlDd the teloclt; of
the Aow in feet pet
me^ notlie'lnfloenaed
by Ihe wind.
seotlon of the prliiu
multiplied bt the Te-
loeltj per mfnnte will
glTa tba qnuitltr pel
of the bed and buik*
the Bctual flow la re-
TtaMOMT or ROD X-I.OAV eAVCETCt.
(From Report on Barge Canal, 1901, Edward A. Bond, M. Y. state Engineer.)
The hTdrometrlc rod may oonBlit of either a plain wooden rod of uniform
diameter, weighted at 1t« lower end with Iron or lead pipe of equal dlam-
•Mr, lo a* to make It tick Teitloally In the water to nearly it* full length.
1472 WATSS-POWXB.
or of » tin tube of uniform diameter, made either oontinnoos or la MctlflM '
fitting water-tightly into each other, and properly weighted with leitei
shot, Dulleta, etc., at the bottom. If such a rod ia placed carefaUj la te
water, bo as to prevent any vertical motion, and its projecting pait li wm
acted upon by the wind, it may be assumed tnat in a snort time it will MM
with the mean velocity of the water in the vertical plane in which It loilk \
When a straight cylindrical rod of uniform diameter Is ImmarscdiaM*'
oally in a moving Sody of water and kept from sinking, it em
therein filaments having different velocities in the direction of the
and eventually acquires an intermediate velocity whlcdi is very ne
mean of those acting upon it. Some of the fluid partidea will be
faster than the rod, while others move slower ; tne former will teal is
accelerate the motion of the rod, both by direct pressure and by the hicnl (
friction, while the latter tend to retard it. In the ensuing state of sfuOt j
brium and uniform motion, the accelerating and retarding foress sn| J
on the rod must be equal, and will form a couple which causes tkeni
to assume a sUghtly inclined position in the water. Furthennore, vta
the channel is regular, and the rod reaches nearly to the bottom, the gcMOl
law according to which the velocity of the successive filaments frosi tti
surface downwards varies, has been determined approximately by expRi-
ment, and it becomes possible to express the sums of the said aoedcrad^
and retarding forces m relatively simple mathematical terma. Fran tfe»
equality of these expressions, it is then found that the rod assmBei tk>
velocity of the water filament, which is located at a depth =afil I^ vbat
(L) denotes the immersed length of the rod. In like manner, the Tdodl;
(V|) of the rod may also be compared with the computed or theoretiesl nets
velocity (v^ of all the water filaments in the vertical line or plane ttcm tft*
surface to the depth (L) ; and as it is found therefrom that (V|) is a littli
less than (o,), it may be eonsidered that (r^) is equal to ti&e mean TdodlF
(vm) for a depth a little greater than the said length (X). Under ordlaan
conditions in canals and rivers with rcffular channels and moderate vdoo-
ties, the immersed length (L) of the rod should be about 94% of the d^A
(!7^ of the water in the vertical plane of observation.
From his extensive experiments at Lowell with such rods 2 indw h
diameter and of different length (L) ranging from 87 to 99 per eeat oi tb«
depth (T)t the latter being made to vary from 8.1 to 9 J^ feet, and witk woo.
velocities (vm) ranging from OJS to 2.8 feet per second, Francis deduced tbt
following empirical formula for finding (vw) from the obeervedvelod^l^
of the rod:
v» = vj 1.102— 0.116 y^^^ — -y
Commenting on the results given bv this formula in comparison vift tti
simultaneous observations of discnarffe over his standard wdr, Mr-
Francis states that taking the whole of uie experiments together, the vtf
age difference is about f of 1 per cent, and that the largest differeaeehis
excess of about 3.7 per cent over the weir measurement when the itkdtj
was only 0.5 foot per second. It is also probable that the above fonA
will not give trustworthy values of (r*) when the immersed length(£)<if ^
rod is less than 75 per cent of the depth ( T); hence it Is desirable to aatfeCD
as nearly equal to < 7) as the character of the bed of the channel will peR»
PracttCAl CoMslderiatloM.— In order that the work of gaufiBf*
water-course with rods may be prosecuted expeditiously and witk wHl
accurate results, certain practical considerations should oe obaesrved. H*
rods should be straight cylinders of uniform diameter having the niiwiirtu*
practicable surface. Their diameter should be as small as is ooaqaAl*
with proper strength and stiffness, and the loading at the bottom shm ^
concentrated so as to bring the center of gravity as low down as posiOiltli
the water, at the same time being rigidly attached so as to remain ia phN
even if the rod is inverted. They should also have ample buoyancy, iaofi*
to bring them quickly to their normal depth of immersion after aecidtftil
submergence, and the projecting portion should be as diort as possible c»
sistent with the function of serving as a marker. In their experinaH
Francis and Cunningham used tin tubes about 2 incihes In diameter, fllll
Grebenau and others used varnished wooden rods, havii^ diaoMten "*
1.2 to in inches. Cunningham also used such rods, but gave the pnft
to the tubes.
HORSB-POWEB OF WATER.
1473
(Pelton Water Wheel Co.)
tAtners' inch is a term much in ase on the Pacific Coast and in the mining
Hons, and is described as the amount of water flowing through a hole 1
Sb square in a 2-inch plank under a head of 6 inches to the top of the
tflce.
Pis. 13 shows the form of measuring-hox ordinarily used : and the follow-
gr table gives the discharge in cublo feet per minute oi a miners' inch
-water, as measured under the various heads and different lengths f^d
l^^tB of apertures used in California.
,-s
Openings 2 Inches High.
Openings 4 Inches High.
ill
Head to
Head to
Head to
Head to
Head to
Head to
Center,
Center,
Center,
Center,
Center,
Center,
5 Ins.
6 Inches.
7 Inches.
6 Inches.
6 Inches.
7 Inches.
Cu.rt.
Cu. Ft.
Cu. Ft.
Cu. Ft.
Cu. Ft.
Cu. Ft.
4
1.348
1.473
1.589
1.320
1.450
1J570
6
i.aNi
1.480
1.696
1.336
1.470
1JB05
8
i.r>9
1.484
1.600
1.344
1.481
1.608
10
1.361
1.486
1.602
1.349
1.487
1.615
12
i.aa»
1.487
1.604
1.362
1.491
1.620
14
1.364
1.488
1.604
1.364
1.494
1.623
16
1.365
1.489
1.605
1.366
1.496
1.626
18
1.366
1.489
1.606
1.367
1.498
1.628
20
1.365
1.490
1.606
1.369
1.499
1.690
22
1.366
1.490
1.607
1.369
1.500
1.631
24
1J66
1.490
1.607
1.360
liiOl
1.632
26
1.366
1.490
1.607
1.361
1J»2
1.633
28
1.367
1.491
1.607
1.361
1.508
1.634
30
1.367
1.491
1.608
1.362
1.503
1.635
40
1.367
1.492
1.608
1.363
1.506
1.637
60
1.368
1.493
1.609
1.364
1.607
1.639
00
i.!m
1.493
1.609
1.365
IJM
1.640
70
1.368
1.493
1.6U9
1.365
1.608
1.641
80
1.368
1.493
1.609
1.366
1.609
1.641
90
1.369
1.493
1.610
1.366
1.609
1.641
100
1.36R
1.494
1.610
1.366
1JX»
1.642
NoTS. — The apertureg /rom which the above meoiuremenU were obtained
nre thrrmqh material J\ tnrhes thick, and the Uncer edge 2 inches above the
^tom of tnemecuuring-hoxt thtu giving full conttxiction.
n^^ir OF w^ATSR ovKR irEms.
fi^efr D«vi ]IK«aaareMieMt.
(Pelton Water Wheel Co.)
Place a board or plank in the stream, as shown in Fig. 14, at some point
rhere a pond will form above. The length of the notch in the dam should
M from two to four times its depth for small Quantities, and longer for
arge qoantitiee. The edges of the notch should be beveled toward the
atake side as shown. The overfall below the notch should not be less than
Miee its depth, that is, 12 inches if the notch is 6 inches deep, and so on.
In the pond, about 6 feet above the dam, drive a stake, ana then obstruct
Jie water until it rises precisely to the bottom of the notch, and mark the
itake at this level, llien complete the dam so as to cause al> the water to
low through the notch, and, after time for the water to settle, mark the
itake again for this new level. If preferred, the stake can be driven with
As top precisely level with the bottom of the notch, and the depth of the
vater be measured with a rule after the water is flowing free, but the marka
1474
WATER-POWKE.
1
are preferable in most oases. The stake can then be wltbdravn ; aad tk^
distance between the marks is the theoretical depth of flov eorresponC^I
to the quantities in the table.
f raacla'a W^rmtuim for ITelra.
As given by
Francis.
Weirs with both end contractions \ /^ _ « *»i«il
suppressed. . ." | V — -»•«*«
Weirs with one end contraction) ^__ «~|,f __ ,^-4 ^1
suppressed J V — •J-SH*
As modiftcdy
Smitk. i
3.29
ik)k
I
zjaik
i
k^
^J
Weirs with full contraction . . ^ = 3.33(/ — .2A)A* 3.»// — ^)
The greatest variation of the Francis formulae from the raloe of c fma
by Smith amounts to 3^ per cent. The modified Francis formulje, says SaiiW
will give results sufficiently exact, when great accuracy is not reqaroi,
within the limits of h, from Ji feet to 2 feet, / being not leas than 3 k.
^ = discharge in cubic feet per second, i = length of weir in feet,i =
effective head in feet, measured from the level of the crest to the lerd d
still water above the weir.
If ^ = discharge in cubic feet per miniite, and I' and h' are taken in iackei.
the first of the above formulss reduces to ^ = OM*k^ • The values are ai-
ficiently accurate for ordinary computations of water-power for
without end contraction, that is, for a weir the full width of the cksBBci
of approach, and are approximate also for weirs with end contractioo vha
I = at least lOA, but about 6 per cent in excess of the truth when / = 44.
^>lr Table.
TabU Showing the Quantity of Water Pasting over Weirs in Cubic Fea
per Minute.
a
c o g
4
4#
S. ^
o . o
Uifi
«?5 ®
•S?-S
= fe i 111
a
OOc
La »•-<
4.85
6.78
6.68
7.80
8.90
10.00
11.23
12.45
13.72
16.02
16.36
17.75
19.17
20.63
22.11
23.63
26.20
26.78
28.43
30.06
31.75
33.45
36.22
36.98
38.80
40.63
42.49
44.39
46.29
48.22
3
6
6
60.20
62.18
64.22
66.26
68.33
60.42
62.56
64.68
66.86
68.98
71.27
73.46
75.77
78.04
80.36
82.63
86.04
87.43
89.82
92.16
94.67
97.11
99.50
102.10
104.63
107.13
108.74
112.31
114.91
117.61
•a fe o^
11
9 ©
51.2.1^^
120.18
122.82
125.52
128.14
130.93
133.65
136.43
138.18
141.99
144.80
147.64
150.47
153.35
156.20
158.14
162.07
161.99
167.89
169.92
173.90
176.93
179.94
182.99
186.03
189.13
192.20
196.32
19&47
201.60
207.94
a
^ a"-"
00-
•►'
& 9
C!^^
3 © e c ^>
16
19
214JS
2».7S
22: JO
23SJ9
9IOt54
34Ti2
364iB
280,S
367.77
29&J8
303J0
310J6
317.0
3S5J3
332.12
3951
347.45
36&.(e
sn>J4
378.12
SSJS7
401.63
417.«
HORSE-PO^ER OF WATER.
1475
Of ITATJfilK.
(Pelton Wheel Go.)
HlMen' Incli Table.
Cable feet T(
»ble.
The following table gives
the horse-
The following table gives the
IK>wei
' of one miners' inch of water
horse-power of
one cubic foot of
ixxsder heads from
one up
to eleven
water per min ute under headF from
Ikvmdred feet. This inch
equals l\
one
up to eleven hundred feet.
ev&bio feet per minute.
•a .
B
B .
a
11
Horse-
^^
Horse-
• '**
Horse-
J Si
Horse-
power.
Power.
^1
Power.
t3 '•'
power.
»
»
X
X
1
.0024147
320
.772704
1
.0016098
320
.616136
20
i)482294
330
.796861
20
.082196
330
J»1234
90
.07M41
340
.820098
30
.048294
340
.647332
40
.096688
360
.846146
40
.U64392
360
.663430
60
.120736
360
.869292
50
.080480
360
.679628
eo
.144882
370
.893439
60
.006688
870
.696626
70
.169029
380
.917686
70
.112686
380
.611724
80
.193176
390
.941733
80
.128784
390
.627822
90
.217323
400
.966880
90
.144892
400
.643920
100
.241470
410
.990027
100
.180080
410
.680018
110
.266617
420
1.014174
110
.177078
420
.676116
120
.289764
430
1.038821
120
.198176
430
.6922^4
190
.313911
440
1.062468
130
.209274
440
.706312
140
460
1.086616
140
.226372
460
.724410
ICO
.362206
460
1.110762
150
.241470
460
.740608
100
.388362
470
1.134809
160
.267668
470
.766606
170
.410499
480
1.169066
170
.273666
480
.772704
180
.434646
490
1.183206
180
.289764
490
.788802
190
.468793
600
1.207360
190
.306862
500
.804900
200
.482940
620
1.266644
200
.321960
520
.837096
210
Ji07067
640
1.303938
210
.%M068
640
.869292
220
^31234
660
1.352232
220
.364166
660
.901488
230
JS56381
680
1.400626
230
.370264
580
.933684
240
.679628
600
1.448820
240
.386362
600
.966880
260
.608676
660
1.669666
260
.402460
650
1.046370
260
.627822
700
1.6U02ilO
260
.418648
700
1.126860
270
.661969
760
1.811026
270
.434016
750
1.20^/360
280
.676116
800
1.931760
280
.460744
800
1.287840
290
.700263
900
2.173230
290
.466842
900
1.448820
300
.724410
1000
2.414700
300
.482940
1000
1.609800
310
.748667
1100
2.666170
310
.499038
1100
1.770780
Wbea tbe Sxact Head la found Im Above Table.
Example. — Have 100 foot head and 60 Inches of water. How many
horse-power ?
By reference to above table the horse^power of 1 inch under 100 feet
hea^ Is .241470. The amount multiplied by the number of inches, 60, will
give 12.07 horse-power.
IVhen Kxact Head la aot Voaad la Table.
Take the horse-power of 1 inch nnder 1 foot head, and multiply by the
number of inches, and then by number of feet head. The product will be
the required hors<»-power.
llie above formula will answer for the cubic-feet table, by substituting
the equivalents therein for those of miners' inches.
NoTs. — The above tables are baaed upon an efficiency of 85 percent.
WATItB-POWEB.
t irk««>lBt In whieb the tr>l«r pua«a nnder hUbi In !>■
jDilrnctad iu (bs old-lHbloEed nj with Oat boudi u tun, ;
luin theorsUiAlefflclflnejrariKipercancj hut slth enmd Isaii. '
I't wheel, which ere Blruged hi thai the water ail«i vllbgnl {
>pfl from the doate Into the tall-raee without boriioxital v^ i
Imum effloleuoT la ■■ great aa tor oTetahol wheel*, and Ot I
ible eBlcleucy I* founif to be abont «) per cent. The velodly of Oi i
lerjr (bonld ba ftboat J> of the theoretical velocitj o( thewatudKb |
srea
atHks* tl
trum the HuBl or bucket; ocenhol wheelf ^T^Tfor falkof 13 fert to » '
(eet; below (lial breoal wbeela ate preleiablo. The capacity of Ihebackid ,
abould be three times tbs volume of water held In each. Thedlitance^Kii ,
InebM In low-breait wheeli, while the opening of boeketa ma; tt I l°l ;
iDcbea In blgh-breaAt, and 9 inohea to 12 Jtubee in low-breaat whew- I
■niRBIIIEB. I
TheMisar be diTided Into two main clauea.Tli., preaaure andlnrabi
toTblaea. Tbe former may be again divided into the [ulluwiaa^ panlM- ,
flow, oatward^ov, and inward-flow turbine*, icfordlng to the directioa li '
turblDe In .
Ilel-aow (biMbh, m
r low falli, not exceeding i
1 ubeel tteing placed at thi
9 level of the tail-race. Tt
le curved Hoateoi the wb(,-. > —
'ranged to work partly by suctloi
be laLl-raee without loae of poww.
ealled downvard-lloii
Fro.
OatHard-flsfT •Wmwtilmt* have a gomewhat higher efllclaney than Ik
paraliel-niiw — u much ng 88 par cent baa been raallied by BoydeD■t■^
Wne ; Fonnievrnn'* hai given a maitmom of TO per cent.
lBwanl-H*w VarlrtHH have been dolgned by Swain and othsa
T«ta made oo a Swain turbine by J. B. Praoeli gave a mailDiam d-
ciencyof M per cent with full lupply, and with the gate a quarter apHi (1
percent, the drcaraferentlal velocity of the wheel ranging from « wB
percent of (be Ibeoretiaai velocity dne to the bead of water. InSwalgi
*- * -■ — vertlea) and oppoaile the golde UaOH,
DIMENSIONS OF TURBINES.
1477
the edffes towards the bottom of the floats being bent into a qoadrant form.
The Victor turbine is claimed to giro 88 per cent under favorable conditions.
Ife reoeives the water upon the outside, and discharges it downward and out-
vard, the lines of discharge occupying the entire diameter of the lower portion
of the wheel, excepting only the space filled by the lower end of the shaft.
Knip«lfl« Xaiwinea are suitable for yerv high falls. The Girard and
Pelton are both of this tvpe. It is advised that pressure turbines be used
on heads of 80 feet or 100 feet, but above this an impulse turbine is best.
A Oirard turbine is working under a fall of 660 feet.
Iiutolllair TnrblMea.
Particular attentioir must be paid to the designing and construction of
water-courses. The forebay leading to the flume should be of such size that
the velocity of the water never exceeds 1^ feet per second, and should be
free from abrupt turns or other defects likely to cause eddies. The tail-race
should have similar capacity and sufficient aepth below the surface of the
stream to allow at least 2 feet of dead water standing when the wheels are
not in motion, and with large wheels, 3 feet to 4 feet ; after extending sev-
eral feet beyond the flume, this may be gradually sloped up to the level of
the stream. It is not uncommon to see 2 feet or 3 feet of head lost In
defective races.
When setting turbines some distance above the tail-race, the mouth of the
draft-tube must be 2 inches to 4 inches below the lowest level of the stand-
ing tail-water. Theoretically draft-tubes may be 30 feet long ; but 20 feet
Is as long as is desirable on account of the dlfliculty of keeping air-tight ;
they should be made as short as possible by placing the turbine at the
bottom of the fall.
Particulars of the setting recommended for Victor turbines are given
below, as an example.
Table of IMmeiialOBJi of Victor Turbine.
B. O.
1
_ 9 P«M
D.
Wo-^ c
,.f3 h
a?3
Up
^ f
s &
ID O O
Is*?
K.
K.
^ ■
o »- • •
uteris
^^ => fl
(4 o (4 at
O •**
« a « d
*^ 35 o
g -o
d
'Sit
s^|3
^11
g O o
Lbs.
166
260
360
600
830
1125
1475
1900
2336
3640
4600
6460
7600
9380
11700
19000
DXJItKIfUOIVS or WRBntSS.
Tables of sizes of turbine wheels vary so much under different makers,
and are so extensive, as not to permit their insertion here, but through the
kindness of Mr. Axel EkstrQm of the General Electric Company I am per-
mitted to print the following sheets of curves for the McCormick type
turbine and the Pelton impulse wheel. From them may be made deier-
minations of dimensions in much shorter time than is necessary by use o'
tables.
DRAULIC TURBIXK!
i
1480 WATER-POWER.
1
Mr. Boss E. Browne states that ** The functions of aiPtoter-wheeUopcratad
by a Jet of water escaping from a nozzle, is to conrert the energy of the jel, I
dae to its velocity, into usef al work. In order to utilize this eaergy fiU?, I
the wheel buclcet, after catching the jet, must bring it to rest b^ofe4^
ohargln£ it, without inducinf turbulence or iwitation of the |»articles. Tls
oannotbe fully etfected, and unavoidable dilficnltlee neceantate the kntf
a portion of the energy. The principal losses occur as follows :
"First: In sharp or angular diversion of the jet in entering, or izlti
course through the oucket, causing impact, or the conversion of a portaoe<4
the energy into heat instead of useful work.
"Second: In the so-called friotional resistance offered to the motiaB<tf
the water by the wetted surfaces of the buckets, causing also the eamrtt-
sion of a portion of the energv into heat instead of useful work.
*' Third : In the velocltv of the water as it leaves the bucket, repnttBt-
Ing energy which has not been converted into work.
" Hence, in seeking a high efficiency, there are presented the foDovici
considerations :
" 1st. The bucket surface at the entrance should be approximately panl-
lel to the relative course of the jet, and the bucket should be curved in g&A
a manner as to avoid sharp angular deflection of the stream. If, for exam-
ple, a jet strikes a surface at an angle and is sharply deflected, a portioa f4
the water is backed, the smoothness of the stream is disturbed, and there
results considerable loss by Impact and otherwise.
2d. The number of buckets snould be small, and the path of the jet in tke
bucket short: in other words, the total wetted surface should be small, u
the loss by friction will be proportional to this.
" A small number of buckets is made possible by applying the jet tai^es-
tially to the periphery of the wheel.
** 3d. The discharge end of the bucket should be as nearly tangentia] to
the wheel-periphery, as compatible with the clearance of the bucket vU^
follows ; and sreat differences of velocity in the parts of the eecspiqr
water should be avoided. In order to bring the water to rest at the dis-
charge end of the bucket, it is easily shown mathematically that the vdo-
ctty of the bucket should be one-half the velocity of the let.
** An ordinary curved or cup bucket will cause the heaping of more or hm
dead or turbulent water in the bottom of the bucket. This dead water is
subsequently thrown from the wheel with considerable velocity, and re|ff«-
sents a large loss of energy.
"The introduction of the wedge in the bucket is an efficient mesas ef
avoiding this loss."
Wheels of this type are very efficient under high heads of water, and ham
been used to a great extent In the extreme western parts of the UDit«<I
States, where the fall is in hundreds of feet. It is difficult to say at vi«<
point of head the efficiency becomes such as to induce the use of some oUMf
form of wheel; but at 200 feet head the efficiencies of both impulse and tor-
bine will be so much alike that selection must be governed by other fsetois.
Tests of one of the leading impulse wheels show efficiencies raryinf ftca
80 % to 86 % according to head and size of jet. However, many farton
besides the efficiency enter into selection of water-wheels, whieh mvit b«
subject to local conditions, and as In most water-power plants, each k%
special case by itself, and selection of I4>paratu8 best fitted in all ways mtst
l^vern.
SHAFTING. 1481
SHAFTING, PULLEYS, BELTING, ROPE-
DRIVING.
Tlmraton gires the following formula) for calculating power and Blse of
•biaf^lng.
Ji.P. = horse-power transmitted.
d = diameter of shaft in inches.
r = revolutions per minute.
For Iron, H.P. = ^; d = 4^ ^ ~
For cold- Mr 8/75 up
r'llediron^.7>.-^;d= yl^-^'
]P*or line shafting
hangers 8 feet
apart.
For transmission
simply, no pul-
leys.
X!. I ir f> '^^^ ^ .f/w 7/./'.
For Iron, i/./*. = ^^ ; a = y —
■'lid iron,j¥.7». = -^ ; rf = y •
fi? I ti » ^^'^ ^ "762.5 ^.P.
For iron, «.P. = -y^; rf=V
r'Ud iron, /f./>.= -g^ *. <' = y z —
Jones and Laughlin*B use the same formulxB, with the following ezoep-
tions :
For line shafts, cold-rolled iron, i/.P. = - . ; rf = v '- — ■'•
00 » r
For transmission and for short-counters,
Turned iron H,P.=i-~\dz=.y .
Cold-rolled Iron /T./'. = - ; 0= v •
PulleTS should be placed as near to bearings as practicable, but care
shiould be taken that oil does not drip from the box into the pulley.
The diameter of a shaft safe to carry the main pulley at the center of a
bay may be found by multiplying the fourth power of the diameter obtained
by the formulae above given, by the length of the bay, and dividing the pro-
duct by the distance between centers of bearings. The fourth root of^he
quotient will be the required diameter.
The following table is based upon the above rule, and is substantially
correct :
1482
SHAFTING, PULLEYS, BELTING, ETC.
•g ® 00
§'3 ®^
in.
2
2i
3
3^
4
5
6i
6
Diameter of Shaft necema^ to carry the Load at the Center ol
a Bay, which is from Center to Center of Bearin^i.
2|ft.
in.
3
3 ft.
3|ft. I 4 ft.
in.
6
8 ft.
»&
Should the load be placed near one end of the bay, multiply the fbivtt
power of the diameter of shaft necessary to safely carry the load at the ea-
ter of the bay (see above table) by the product of the two ends of the ibaft,
and divide this product by the product of the two ends of the shaft vksv
the pulley is placed in the center. The fourth root of this qaotieot win be
the required diameter.
A shaft carrying both receiving and driving pulleys should be flgnreda
a head-shaft.
I
]>«ilc€tiom of ftliafllBir*
(Pencoyd Iron Works.)
As the deflection of steel and iron Is practically alike under similsr ras-
ditionsof dimensions and loads, and as shafting is usually determined br
its transverse stiif ness rather than its ultimate strength, nearly the «aw
dimensions should be used for steel as for iron.
For continuous line-shafting it is considered good practice to Unit tbt
deflection to a maximum of t^o of an inch per foot of length. The v«^
of bare shafting in poimds — 2.6 tPL = W^ or when as fully loaded vn^
Jiulleys as is oustomarv in practice, and allowing 40 Ibe. per inchof vidtk
ur the vertical pull of tne belti;, experience shows the load in pounds to^
about 13 (l^L =z W. Taking thetnoaulus of transverse elasticity at S6/0MW
lbs., we derive from authoritative formulse the following :
i =>yi73lP, d = V -^. tor bare shafting;
L = ^ 175 (/*, d = y T^g, for shafting carrying pulleys, etc.:
L being the maximum distance in feet between bearings for c<mtiaao6i
shafting subjected to bending stress alone, d = diam. in inches.
The torsional stress is inversely proportional to the velocity of rotattoSi
while the bending stress will not be reauced in the same ratio. It is there-
fore impossible to write a formula covering the whole problem and (ofr
ciently simple for practical application, but the following rules are corrert
within the range of velocities usual in practice.
Fur continuous shafting so proportioned as to deflect not more than j^
of an inch per foot of length, allowance being made for the veakesbf
effect of key-seats,
._ ^/iMH.P. ^^
^ - V — r — '^ = ^y7a0rf» for bare ahafts ;
SHAFTING.
1483
140d>, for shafte carrying pulleya^ etc.
t# == diam. in incheii, Z r= length In feet, r = revola. per minute.
1?1&« followrlng table (by J. B. Francis) gives the greatest admlBsible dis-
tatnoea between the bearings of continuous shafts subject to no transverse
Btrain, except from their own weight.
Distance between
Bearings in ft.
/ * V
rMmm. of Shaft, Wronght-iron Steel
in inches Shafts. Shafts.
2 15.46 16.89
3 17.70 18.19
4 19.48 20.02
5 20.90 21.67
Distance between
Bearings in ft.
/ * X
Diam. of Shaft, Wrooght-iron Steel
in inches* Snafta. Shafts
6 22.30 22.92
7 23.48 24.13
8 24ii6 26.23
9 25.63 26.24
Xhe writer prefers to apply a formula In all caaea rather than uae tables,
shafting ia nearly always one^lxteenth inch less in diameter than the
sizes quoted. The following tables are made up from the formulte first
gi ven In this chapter.
As Prime Mover or Head Shaft well Supported by Bearings.
1
Revolutions per Minute.
60
80
100
126
160
176
200
226
260
276
300
Infl.
H.P.
HJ».
H.P.
HJ».
H.P.
H.P.
H.P.
HJP.
H.P.
H.P.
H.P.
If
2.6
3.4
4.3
6.4
6.4
7JS
8.6
9.7
10.7
11.8
12.9
2
3.8
6.1
&4
8
9.6
11.2
12.8
14.4
16
17.6
19.2
2\
6.4
7.3
8.1
10
12
14
16
18
20
22
24
gl
7.6
10
12iS
16
18
22
26
28
31
34
37
3
10
13
16
20
24
28
32
36
40
44
48
3
13
17
20
26
30
36
40
46
60
66
60
^
16
22
27
34
40
47
64
61
67
74
81
3
20
27
34
42
51
69
68
76
86
93
102
3
25
33
42
52
63
73
84
94
106
115
126
4
30
41
51
64
76
80
102
115
127
140
153
H
43
68
72
90
lOR
126
144
162
180
198
216
5
60
80
100
126
160
176
200
226
250
276
300
5i
80
106
133
166
190
233
266
299
333
366
400
Appr«xtBi«te C«Btov* of Itoartaipa for WrooAt IroM Idae
•balte CarryiBiT ^ ■'lair Proportloa of Palleja.
Shaft, Diameter Inches . .
7
1}
2
2i
2*
9
9*
10
3*
11
4
12
4*
c. to c. Bearings — Feet . .
7J
8
8*
13
Shaft, Diameter Inches . .
5
6*
6
15
6*
16*
7
16
7*
17
8
18
9
19
10
c. to c. Bearings -^ Feet . .
13*
14
20
1484
SHAFTING, PULLEYS, BELTING, ETC.
LnrB-BHAFTIliO, BSABIlTaS 8 FT. APART.
•
5
K«Tolatioii8 per Minute.
100
126
160
176
200
226
250
275
300
as
m
Ins.
H.F.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
If
6
7.4
8.9
10.4
11.9
13.4
14.9
16.4
17.9
19.4 £3
1}
73
9.1
10.9
12.7
UJi
16.3
18.2
20
21.8
2S.6 &i
2
8.9
11.1
13.3
16.6
17.7
20
22.2
24.4
26.6
28^ S
2|
10.6
13.2
164»
18JS
21.2
23.8
'MA
29.1
31.8
34.4 ;r
24
12.6
16.8
19
22
26
28
31
35
38
41 -41
21
16
18
22
26
29
33
37
41
44
48 (S8
2I
17
21
26
80
84
39
43
47
52
56 ff
^
23
29
34
40
46
62
68
64
60
75 81
3
30
37
45
62
60
67
76
82
90
97 »
31
38
47
67
66
76
86
96
104
114
123 ,U8
31
47
69
71
83
96
107
119
131
143
156 'Iff
M
68
73
88
102
117
132
146
162
176
190 !»
4
71
89
107
126
142
160
178
196
213
331 ,^
1
POWBB TRAKSMI88ION ONLY.
■
s
ReYolutions per Minute.
100
126
160
176
200
238
267
30O
333
1
387
4m
HJ».
Ins.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
HJ».
H.P.
H.P.
HJ.
1|
6.7
8.4
10.1
11.8
13JS
16.7
17.9
20.3
22J5
24.8
SA
1
8.6
10.7
12.8
16
17.1
20
22^
26.8
28.6
31^
3U
1
10.7
13.4
16
18.7
21Ji
26
28
32
36
39
4S
1
13.2
16.6
19.7
23
26.4
31
36
38
44
48
ss
2
16
20
24
28
32
87
42
48
63
68
M
19
24
29
33
38
44
51
57
63
70
n
2z
22
28
34
39
46
62
60
68
75
83
»
2}
27
33
40
47
63
62
70
79
88
96
JS
4
31
39
47
64
62
73
83
93
104
114
&
^
41
62
62
73
83
97
111
125
138
153 W
3
64
67
81
94
108
126
144
162
180
19B
9»
H
68
86
103
120
137
160
183
206
228
250
S3
86
107
128
160
171
200
228
257
285
313
3@
■Ion«-power !lrr»asnittted by Cold-rolled Xroa SfeafUir'
AB PRIME MOVER OR HEAD SHAFT WELL SUPPORTED BY BEAB1566-
•
Revolutions pet
Minute.
5
60
80
H.P.
100
126
160
176
200
225
250
215
ao»
Ins.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
HJ*.
U
2.7
3.6
4.6
5.6
6.7
7.9
9.0
10
11
12
13
if
4.3
6.6
7.1
8.9
10.6
12.4
14.2
16
18
19
a
2
6.4
8.6
10.7
13
16
19
21
24
26
29
»
9
12
16
19
23
26
30
34
38
4&
4«
21
12
17
21
26
31
36
41
47
52
57
e
21
16
22
27
36
41
48
66
62
70
76
0
3
21
29
36
46
64
63
72
81
90
98
m
^l
27
36
46
67
68
80
91
108
114
126
ist
3
34
46
67
71
86
100
114
129
142
167
m
8
42
66
70
87
105
123
140
158
174
193
m
4
51
69
86
106
128
148
170
192
213
244
SG6
4
73
97
121
161
182
212
243
273
30S
333
S»
1
8HAFTIXQ.
1485
liiKS-flHAFrnrG, bsabikos 8 ft.
APABT.
•
Beyoluiiona per Minute.
•
s
100
126
150
176
200
225
H.P.
260
276
300
825
860
Ins.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
HJ».
HJ».
H.P.
H.P.
ix
6.7
8.4
10.1
11.8
13.5
15.2
16.8
18.6
20.2
21.9
23.6
]1
8.6
10.7
12.8
15
17.1
19.3
21.5
23.6
26.7
28.9
81
|2
10.7
13.4
16
18.7
21.5
21.2
26.8
29 JS
32.1
34.8
89
ji
13.2
16.5
19.7
23
26.4
29.6
32.9
36.2
39.6
42.8
46
2
16
20
24
28
32
36
40
44
48
62.
66
«gi
19
24
29
33
38
43
48
62
57
62
67
2I
82
28
84
39
45
60
66
61
68
74
80
29
27
33
40
47
53
60
67
73
80
86
94
21
31
39
47
54
62
69
78
86
93
101
100
2»
41
52
62
73
83
93
104
114
126
136
146
3
54
67
81
94
108
121
134
148
162
176
189
^
68
86
103
120
137
154
172
188
206
222
240
85
107
128
160
171
192
214
236
267
278
800
POWEB TBANSSUB8ION AXD SHOBT COUNTBBS.
•
g
Revolutioiis pei
' Minute.
s
100
126
150
•
H.P.
175
200
233
267
300
333
367
400
Ins.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
H.P.
HJ».
H.P.
H.P.
6^
8.1
9.7
11.3
13
15.2
17.4
19.5
21.7
23i)
26
8.6
10.7
12.8
15
17
19.8
22.7
26Ji
28.4
31
31
1'
11.2
14
16.8
19.6
22.5
26
30
33
37
41
46
14.2
17.7
21.2
24.8
28.4
33
38
42
47
52
57
18
22
27
31
36
41
47
63
69
66
71
*1_
:
22
27
33
38
44
51
58
66
72
79
87
2
26
33
40
46
53
62
71
80
86
97
106
^
32
40
47
65
63
73
84
96
106
116
127
2
38
47
57
66
76
89
101
114
127
139
152
2
44
55
66
77
88
108
118
138
148
163
178
2
62
65
78
91
101
121
138
155
172
190
207
2
69
84
99
113
138
161
184
207
231
264
877
3
90
112
136
157
180
210
240
270
300
330
360
Hollow J^liafta.
I^t d be the diameter of a solid shaft, and d,rf, the external and internal
diameters of a hollow shaft of the same material. Then the shafts will be
of equal torsional strength when d*
_ rfi*-^,*
A 10-inch hollow shaft with
internal diameter of 4 inches will weigh 16% less than a solid 10-inch shaft,
but its strength will be only 2.66 % less. If the hole were increased to 5
inches diameter the weight would be 25% less than that of the solid shaft,
and the strength 4.26 % less.
T»blo for IjaylBr Out Sliiaftlmc*
The table on the following page is used by Wm. Sellers & CJo. for the lay-
ing out of shafting.
r
1486 SHAFTING, PULLEYfl, BELTINi
BELTIKG. 1487
On-wilii says the number of arms is arbitrary, aad gives the following
l«&o« :
a = N amber of arms = for a single set = 3 -f i^*
d = diameter pullev.
t ^ thicliness of eoge of rim of pulley == .76 inches -|- :006<f .
T= thickness of middle of rim of pulley = 2f + c.
b = breadth of rim of pulley = 1(^4- 0.4;.
B = breadth of belt.
h = breadth of arm at hub "
for single belt = .6337 y —
for double belt = .798 i/—
" a
hi =z breadth of arm at rim = J A.
e = thickness of arm at hub = 0.4 h.
e\ = thickness of arm at rim = 0.4 A|.
c = crowning z=J^b,
L = length oi huD = about | h,
Reuleaox says pulleys of more than one set of arms may be considered
IS separate pulleys, except proportions of arms may be 0.8 to 0.7 that of
In^le-^trm pulleys.
To I'iMd SIse of Pulley.
/> = diameter of driver, or No. teeth in gear.
d = diameter of driven, or No. teetli in pinion.
Rev •=. revolutions per minute of driver.
rev =: revolutions per minute of driven.
- Dx Rev I) X Rev
a = • rev = t •
rev d
]BBI<TK]V«.
The coefficient of friction of bolts on pulleys varies greatly, and it is there
fore customary to use some arbitrary formula that has proved safe in
practice.
d r= diameter pulley in inches.
wd = circumference.
V = velocity of belt (or pulley face) in feet per minute.
a = angle of arc of contact, commonly assumed as 180°.
I = length of arc of contact in feet = -z„^i;r'
4320
i^= tractive force per sauare inch cross-section of belt.
to =. width of belt in inciies.
t = thickness of belt in inches.
F
S = tractive force per inch of width = — •
rpm = revolutions per minute.
w d
XT p ^ V ^ S _ d yy S X rpm
"" 33000 "" 12edG(»
A rule in common use for approximate determination of the H.P. of belts
to, that a single belt 1 inch wide, traveling 1000 feet per minute, will trans-
mit 1 horse-power. This corresponds to a strain on the belt of 33 lbs. per
Inch of widtn.
1488
8HAPTIKG, PULLEYS, BELTIN^G, ETC.
Authorities say single bells oau be safely worked at 45 lbs. strain pa
inch of width, and on this basis
-y _ _ pto _ dwx rpm
^•^"- 733 ~ M00~'
Double belts are said to be able to transmit power in tbe ratio of 19 to 7
for single belts.
H.P.ofdoubleb«IU = ^ = ii?^I5?.
If the double belt is twioe the thickness of the single belt, then it b fdr
to assume that it will transmit twice the power, and
H. P. of double belt = ^-r^r = *-^
1400
A. W, Ifairle (Trans. A.S.M.E., toL ii. 1881) gives the folloviag
formula
Where C= 1 — 10-«>»"'*.
/ = coefficient of friction.
Hovac-^ower of a Belt one Inch It'Me, Arc of C4
Ck)mparison qf Different Formulw.
ttmdltmp.
a
o** O
® ®
10
ao
30
40
60
60
70
80
90
100
ilO
120
fl
Form. 5
>>hl .
Form. 1
Form. 2
Form. 3
Form. 4
Donble.
?ft5
2-2
H.P. =
H.P. =
H.P. =
H.P. =
Belt
^^2
uw
VfV
uw
wv
H.P. =
660'
1100
1000
733
fCV
613
600
60
1.00
M
.60
.82
1.17
1200
100
2.18
1.00
1.20
1.64
2.34
]800
160
3.27
1.64
1.80
2.46
3.51
2400
200
4.36
2.18
2.40
3.27
4.68
3000
260
6.46
2.73
3.00
4.09
6.86
3600
300
6J36
3.27
3.00
4.91
7.02
4200
360
7.63
3.82
4.20
6.73
8.19
4800
400
8.73
4.36
4.80
6.66
9.36
5400
460
9.82
4.91
5.40
7.37
10^
0000
600
10.91
5.45
6.00
8.18
11.70
6600
660
■ « «
• • •
• • •
• • •
• « •
7200
600
■ • •
• • •
• « •
• • ■
• • •
Naf le's Pons,
^'/single
Belt.
^. Laeed. Blreled.
.73
1.14
IM
2J4
2J5
3^
2M
4J3
3.48
5JS
3.96
€.»
4^
^n
4.50
73S
4.55
T.74
4.41
7je
4.06
7Jf
3.49
7.75
iridtli of Belt for a givea Btorso-
The width of belt required for any given horse-power may be obtained
by transposing the formulee for horse-power so as to give the valne of v.
Tlius:
560 H.P. 9.17 H.P. 2101 H.P. 225 H.P-
From formula (1), w =
From formula (2), w =
From formula (3), w =
From formula (4), w =
From formula (5),* w =
1100 H.P.
1000 H. P.
V
733 H.P.
17
613 H. P.
V
18.33 H. P.
V
16.67 H. P.
r
12.22 H. P.
V
8.56 H. P.
* For double belU.
d X rpm
4202 H.P.
d X rpm
3820 H.P.
dX rpm.
2800 H.P.
d X rpm
1960 H. P.
L X
630H.P.
L xrpm'
SODH.P.
X Xfp»'
360 H.P.
L xrpm'
257 H. P.
d X rpm L xrfM
^
BELTING.
1489
i.«Br*k •' Belt.
.Approximate rule ; two pulleys j / "^--ii— 5!! J x 3.1416 1 + [2 X distanoe
l>o^'ween centers] = length of belt. *
JLenrth of Belt In Roll.
Oatftide diameter roll in inches 4- diameter hole X number turns x -1300
= length of belt in inches for double belt.
fVolgrtai of B«lt (approximate).
I>eiiffth in feet X width in inches t -u^ , , -, ». ,* -r^i *, i. ««
= ^ = weight of single belt. Divide by 8 for
doTible belts.
n[oi«e«Powor VraMaialttocl by MAght, lioulile BodloM
JBiolMar-
(Buckley.)
-Width,
Inches.
4
6
8
10
12
14
16
18
20
22
24
•S 2000
14
22
29
36
43
60
68
66
72
80
87
B 2400
17
26
36
44
52
60
70
78
88
96
105
fe 2800
S, 3000
20
30
40
51
61
71
81
91
102
112
122
22
33
44
54
65
76
87
98
108
120
131
-S 3500
£ 4000
25
38
60
63
76
89
101
114
127
140
163
29
43
68
73
87
101
116
131
146
160
174
a 4500
•= 6000
32
49
65
82
98
114
131
147
163
180
196
36
55
73
91
100
127
145
163
182
200
218
Speed
40
60
80
100
120
140
160
180
20O
220
240
44
65
87
100
130
153
176
200
218
240
260
(Speed X width ~- 550 =r horse-power, light, double.)
(Horse-power X 660-^ speed = width, light, double.)
br II«avj, Dovble Endl
(Speed X width -f 460 = horse-power, heavy, double.)
(Horse-power x 460 4- speed =: width, heavy, double.)
Width,
Inches.
4
6
8
10
12
14
16
18
20
22
24
min.
18
27
36
43
61
60
70
80
86
96
104
21
31
42
63
62
72
83
94
105
115
120
S 2800
P, 3000
24
36
48
6!
73
85
96
100
122
136
146
27
40
53
66
78
90
104
.118
129
144
157
"5 3600
30
45
60
75
91
106
121
137
162
168
184
J 4000
86
62
70
88
104
121
139
167
174
192
2U0
a 4500
•9 5000
38
60
78
98
118
137
157
176
196
216
235
43
66
87
110
130
152
174
196
218
240
263
"S 5600
48
72
96
120
144
168
192
216
240
264
288
§, aw
52
78
1<A
122
153
183
210
240
262
288
312
n
1490
SHAPTINO, PULLKY8, BELTING, KTC.
r= Glroumferenoe of rope in inchos.
1)-=. Diametor of pulley in feet.
i?= lierolatiooB per minute.
Q ^ D w Jl
Horse-power of Hope : s*|q = H.P.
or, Half the diameter of rope multiplied by the hundre(b of feet per
ute traveled. (L. I. Seymour.)
Breaking strength of manila rope in pounds = C* x coefficient. Th»
coefficient varies from 900 for Hncn to 700 for 2-inch diameter rope. 1^
following is a reliable table prepared by T. Spencer Miller, M.E. (See E»-
fineering Newt, December 6, 1890.)
Diameter.
Ultimate Strength.
2.000
3,250
4,000
6,000
7,000
9,360
10,000
13,500
16,000
18,200
21,760
25,000
CoeAdflDt.
900
830
790
780
9CS
760
745
735
712
TOO
This table was compiled by averaging and graduating results of tests at
the Watertown Arsenal and Laboratory of Ri^le Brothers, in Philadelpkis.
Weight of manila rope in pounds per foot =: JOSi (Cireumfereoee is
Inches)*. (C. W. Hunt.)
or, diameter of rope in inches squared = weight in pounds per yardsp-
prozimately.
The coelffcient of friction on a rope working on a cast-iron pulley =.9JS;
when working in an unsreased groove it is increased about tliree times, or
from 0.57 to 0.84. If the pulleys are greased, the coefficient is redoeed
about one-half. It has been found by experiment that a rope 6 inches cir-
cumference in a grooved pullev possesses four times the adhesive resistaBce
to slipping, exhibited bv a hali-wom, ungreased 4-lnch single belt.
The length of splice should be 72 times the diameter of rope. The streBsA
of a rope containing a properly made "long splice** was found lobe TjDOl
pounds per square inch of section.
A mixture of molasses and plumbago makes an excellent dope for tniw-
mitting ropes. Grease and oils of all kinds should be kept from traofmu*
sion ropes, since, as a rule, they are injurious.
Following is another formula for horse-power of manila rope :
^•^' " 33000 •
in wliich H.P. is the horse-power transmitted by one rope, V the Telocity ii
feet per minute, 7^ the maximum working stress, and C the centrif ipj
tension, so that (7*o— <7) is the net tension available for the transmJsaiao oi
power. Taking the total maximum stress at 20OtP and allow 20 % of (jiis
for slack side tension, we have T^ zr lOOrf*, so that H.P. =^ ^KgS — '
A table has been calculated by this rule, giving the borse-pover per log^
transmitted at various speeds.
^
ROPE DRIVING.
1491
C= Cbktbifuoai, Tension is Manila Bopbs-
-POUKDS.
Nominal Diameter of Rope In Inches.
-'S«S
0.7
ft
1.1
f
1.6
1
2.1
1
2.7
H
li
If
li
u
11
2
lOOO
3.4
4.3
6.1
6.2
7.2
8.3
It
1600
1.6
2.4
3.4 > 4.7
6.2
7.6
9.7
11
13
16
18
26
2000
2.7
4.3
6.1
8.2
11
13
17
20
24
28
33
44
2500
4.3
6.7
9.6
13
17
21
27
32
38
46
62
60
aooo
6.2
9.7
13
18
24
30
39
46
66
64
74
100
8SOO
8.4
13
19
26
34
42
63
63
76
89
102
136
4000
11
17
24
33
n
64
69
82
98
116
133
177
4600
14
22
31
42
69
87
103
125
146
168
223
5000
17
27
39
52
69
86
109
129
156
183
210
276
6600
21
33
47
63
83
104
132
166
189
221
254
332
eooo
24
3D
56
76
99
126
167
188
225
257
308
396
6500
39
46
66
88
116
146
183
217
261
807
363
462
Horae
-Pow
«r of Maalla Ropes.
Nominal Diameter of Rope in Inches.
9 *^ -fc^Zl
h
ft
_
ft
i 1
H
U
1ft
1*
1ft
1|
2
2000
2.25
3m
5.14
6.84
9.08
11.5
14.0
17.0
20.3
23.8
27 JJ
36.1
2100
2.36
3.67
6.27
7.16
9.40
11.8
14.7
17.8
21.1
24.8
28.8
37.6
3200
2.46
3.82
6.48
7.46
9.80
12.3
15.3
18.6
22.0
26.9
30.0
39.2
2900
2^66
3.98
6.71
7.76
10.2
12.8
16.9
19.3
22.9
26.9
31.2
•40.8
MOO
2.62
4.10
6.89
7.98
10.5
13.2
16.4
19.8
23.6
27.7
32.2
42.0
2500
2.70
4.21
6.06
8.21
10.8
13.6
16.8
20.4
24.3
28.6
33.1
43.2
2000
2.78
4.33
6.21
8.43
ll.l
14.0
17.3
21.0
25.0
29.3
34U)
44.4
2700
2.85
4.46
6.39
8.67
11.4
14.4
17.8
21.6
25.6
30 J>
35.0
46.6
2000
2.94
4JS0
6.59
8.93
11.76
14.8
18.3
22.2
26.4
31.0
36.0
47.0
2900
3.00
4.68
6.73
9.13
12.0
16.1
18.7
22.7
27.0
31.6
36.8
48.0
3000
3.06
4.78
6.87
9.32
12.3
16.4
19.1
23.2
27.6
32.3
37.6
49.1
3100
3.12
4.87
7.01
9iX)
12.5
16.7
19.6
23.6
28.2
33.0
38.3
60.0
3200
3.18
4.97
7.14
9.70
12.7
16.0
19.9
24.0
28.7
33.7
39.0
61.0
3900
3.25
6jm
7.27
9.80
13.0
16.3
20.3
24.6
29.2
34.3
39.8
62.0
3400
3.30
6.16
7.39
10.0
13.2
16.6
20.6
25.0
29.7
34.8
40.4
62.8
3600
3.36
6.22
7.60
10.2
13.4
16.9
20.9
25.3
30.1
35.4
41.0
63.6
3600
3.40
6.30
7.61
10.3
13.6
17.1
21.2
26.7
30.6
36.9
41.6
64.4
3700
3.44
6.36
7.70
10.4
13.7
17.3
21.6
26.0
30.0
36.3
42.1
66.0
3800
346
6.40
7.76
10.6
13.8
17.4
21.6
26.2
31.1
36.6
42.4
66.4
3000
3.49
6.46
7.81
10.6
13.9
17.6
21.8
26.4
31.4
36.9
42.7
55.8
4000
3.61
6.49
7.86
10.6
14.0
17.7
21.9
26.5
31.6
37.1
48.0
66.1
4100
3.63
6JS2
7.92
10.7
14.1
17.8
22.0
26.7
31.8
37.3
43.2
56.4
4200
3.66
6.64
7.96
10.8
14.2
17.9
22.1
26.8
31.9
37.6
43.4
66.8
4300
3JB6
6.66
7.98
10.8
14.2
17.9
22.2
26.9
32.0
37.6
43.6
56.9
4400
3jyi
5iS6
7.99
10.8
14.2
18.0
22.2
27.0
32.1
37.6
43.6
67.0
4600
3.66
6.66
7.96
10.8
14.2
17.9
22.2
26.9
32.0
37.6
43.6
66.9
4000
3.66
6.54
7-96
10.8
14.2
17.9
22.1
26.8
31.9
3'/JJ
43.4
56.8
4700
3.63
6.50
7.90
10.7
14.1
17.8
22.0
26.6
31.7
37.2
43.1
56.4
4800
3.61
6.48
7.86
10.7
14.0
17.7
21.9
26.6
31.6
37.1
43.0
56.2
4900
3.49
6.46
7.81
10.6
13.9
17.6
21.8
26.4
31.4
36.9
42.7
65.8
6000
3.46
6.38
7.73
10.6
13.8
17.4
21.6
26.1
31.0
36.4
42.2
66.2
6100
3.43
6^
7.67
10.4
13.7
17.2
21.3
25.9
30.8
36.2
41.9
64.8
6200
3.38
6.26
'f.66
10.2
13.6
17.0
21.0
25iS
30.4
35.6
41.3
64.0
6300
3.34
5.20
7.47
10.1
13.3
16.8
20.8
26.2
30.0
36.2
40.8
63.4
6400
3.28
6.11
7.34
9.96
13.1
16.6
20.4
24.8
29.4
34.6
40.1
62.6
6500
3.21
6.00
7.20
9.75
12.8
16.2
20.0
24.2
28.9
33.9
39.3
61.4
6000
2.78
4.33
6.21
8.43
11.1
14.0
17.3
21.0
25.0
29.3
34.0
44.4
6600
2.17
8.38
4.86
6.60
8.6
10^
13.6
16.4
19.6
22.9
26.6
34.7
1492
SHAFTING, PULLEYS, BELTING, ETC.
ttOR$E POfWrER
o
o
is
5 >
: i
go
ft
5'
I-
1
>
FIO. 36L
ROPE DRIVING.
1493
«»rae-Power of ^ St«Tedor« " Tmuiniliislom Itope at
n tliJs table the eflfect of the centrifugal force ha« been taken into con-
er&t^ion, and the strain on the fibers of the rope is the same at all
>e<ls -when transmitting the horse-power given in the table. When more
tn one rope is used, multiply the tabular number by the number of the
;»e«. At a speed of 8,400 per minute the centrifugal force absorbs all the
oinr&l>le tension the rope should bear, and no power will be transmitted.
of «li« Hono-Powor of Tns
(Hunt's Formula.)
nsailaaloB JlopOt
i
Speed of the Rope in Feet per Minute.
•
1,600
2,000
2,600
3,000
3,600
4,000
4,500
5,000
6,000
7,000
8,400
cn
k
1.46
1.9
2.3
2.7
3.
4.6
3.2
3.4
3.4
3.1
2.2
.0
.20
ft
2^
3.2
3.6
4.2
5.0
5.3
5.3
4.9
3.4
.0
.26
s
33
4.3
5.2
5.8
6.7
7.2
7.7
10.8
7.7
10.7
7.1
4.9
.0
.30
1
4JS
5.9
7.7
7.0
8.2
10.7
9.1
9.8
12.8
9.3
12.5
6.9
.0
.36
1
6.8
9.2
11.9
18.6
13.6
13.7
8.8
13.8
.0
.42
li
9.2
12.1
14.3
16.8
20.0
21.2
21.4
19^
.0
.54
1*
13.1
17.4
20.7
23.1
26.8
28.8
30.6
30.8
28.2
19.8
U)
.60
ii
18.
23.7
28.2
32.8
36.4
39.2
41.5
41.8
37.4
27.6
.0
.72
2
23.2
30.8
36.8
42.8
47.6
51.2
64.4
54.8
50.
35.2
.0
.84
For a temporary installation when the rope is not to be long in use, it
might be advisable to increase the work to double that given in t£e tables.
•lip of Hopes and Belts.
(W. W. Christie.)
Some French trials, with constant resistance, the power expended and
slip in several modes of transmission was as follows :
Ropes, 158JH gross h.p.. Slip, 0.33 per cent.
Cotton belt, 169.67 " " 0.78 "
Leather »• 168.84 •* " 0.96 "
•» " 180.23 " •' 0.78 ••
Stated in percentage value, the results were :
Ropes, 100.00 gross power. Slip, 0.100.
Cotton belt, 100.87 " " 0.237.
Leather " 100.37 ** " 0.292.
•• •• 101.07 •• ** 0.237.
r
1494
SHAFTING, PULLEYS, BELTING, ETC.
Manila Cordage.
Tarred
Size. Clr-
cumier'ce.
Inches.
Size,
Diameter.
Inches.
Wei^t of
Feet in
one
Fathoms.
Pound.
31
20
44
14
60
10
79
n
99
6
122
5
146
4
176
3S
207
3
240
2i
275
2i
906
2
S66
lA
396
ir
490
]|
595
1
705
10 in.
825
8
■
900
7
■
1100
6
■
1255
5
•
1415
6 1
1585
M
\
Breaking Strain
of New Bopes.
Pounda.
W^
«»
t«(
For Bopes in use
deduct I from
these figures, for
chafing, etc.
MOO
4000
5000
0000
7000
8600
9600
11000
12500
14000
16000
20000
24000
27000
SlfiOO
37000
42600
48600
54500
61500
41
ad
100
1-X
155
19t
300
455
500
750
910
HBQ
1236
14fX»
1600
1830
Hawser laid will weigh | less.
ITotea om the lJ«ea of ITlre
(Boebling.)
Two kinds of wire rope are manufactured. The most pliable Tarietj ckmi-
tains 19 wires in the strand, and la generally used for hoisting and rounlz^
rope.
For safe working load allow ^ or f of the ultimate strength, aeoordlng to
speed, BO as to get good wear from the rope. Wire rope is as pliable as nev
hemp rope of the same strength ; but the greater the diameter of tbe
sheaves the longer wire rope will last.
Experience has proved that the wear increases with the speed. It is,
therefore, better to increase the load than the speed. Wire rope most sot
be coiled or uncoiled like hemp or manila — all untwisting or kinking m»t
be avoided.
In no case should galvanized rope be used for running. One day's vat
scrapes off the zinc coating.
Viable of fttralMn Produced Uy Iioada
MncllMod PI
Elevation in 100 Ft.
Ft. Deg.
10= 5^
20=11
30
=:ia|
40 = 21|
50=26$
60 = 31
70 = 35
80 = 38|
Strain in Lbs. on
Hope from n Load
of 1 Ton.
212
404
586
754
905
1010
1166
1260
Elevation in
100 Ft.
Ft. Deg.
90 = 42
100 = 45
110=47]
120 =
130 =
140 = 64J
160 =
160 = 58
Strain in Lbs. oa
Bope from a Load
of 1 Too.
1M7
1419
1487
1544
1S92
1633
]«n
17D9
1
WIRE ROPE.
1495
Vabl« of TraBsniMioB of Powor bj fTlro
Showing necessary size and speed of wheels and rope to obtain any de-
tired amoont of power.
(Roebllng.)
IMam.
of
'^fV'heel
in Ft.
8
9
Diam.
Diam.
No. of Rev-
of
Horse-
of
olations.
Rope.
Power.
Wheel
in Ft.
80
J
3.3
10
100
4.1
120
.
6.
140
6.8
80
/b
6.9
11
100
fe
8.6
120
10.3
140
?«
12.1
80
,
10.7
12
100
•
13.4
120
■
16.1
140
'
18.7
80
•
16.9
13
100
'*-
21.1
120
A
26.3
80
f
22.
14
100
t
27.5
120
1
33.
80
f
41JS
16
100
61.9
120
f
1
62.2
No. of Rev-
olutions.
80
100
120
140
80
100
120
140
80
100
120
140
80
100
120
80
100
120
80
100
120
Diam.
of
Rope.
Horse-
Power.
58.4
73.
87.6
102.2
76 J»
M.4
113.3
132.1
99.3
124.1
148.9
173.7
122.6
163.2
183.9
148.
186.
222.
217.
269.
300.
NoTB. For list of transmission ropes, see page 1325.
The drums and sheaves should be made as large as possible. The mini-
mum size of drum Is given in a column in table.
It is better to increase the load than the speed.
Wire rope is manufactured either with a wire or a hemp center. The
latter is more pliable than the former, and will wear better where there is
short bendins. The weight of rope with wire center is about 10 per cent
more than with hemp center.
r
1496
CHAINS.
CHAIir.
The size of chain is determined by the Bise of the ttock used in
the links.
The strength of the iron always used for chains is from 41,000 to
tensile strength per square inch.
Coll CbAlm.
(John C. Schmidt A Co., York, Pa.)
m.
Size of
Links
iron
pet
Foot.
in Ins.
3-16
13
1-4
12
6-16
11
3-8
10
7-16
9
At. Weight
per 100
Ft. in Lbe.
46
76
120
150
200
Proof
Size of
Links
Load in
Iron
per
Foot.
Lbs.
in Ins.
600
1-2
8
1,400
9-16
7
2,600
6-*
6
4,000
a-4
H
6,000
7-8
6
At. Weight
per 100
Ft. in Lb».
226
320
400
690
770
•h«rt MAmU ChalBM.
Proqf Tetts Adopted November 11^ 1896.
(Jones & Laughlins, Limited.)
Size.
(Ins.)
Proof.
(Lbs.)
BB
Crane.
(Lbe.)
BBB
Crane.
(Lbs.)
ATersfe
W«rfit
per ToctL
(Lbs.)
^
700
770
900
£
*
1,200
1,320
1,500
3
A
2,600
2,760
3,200
1.2
1
3,600
8,860
4.425
1J
n
4,800
6,280
6,100
2i)
6,200
6,820
7,860
23
fy
7,800
8,680
9,870
3.2
f
9,000
10,500
12.150
4.2
^
"»S2
12,660
14,560
SA
13,800
16,180
17,476
5J9
}|
16,200
17,820
20,500
6.7
y
18,800
20,680
23,780
TJ
ll
21,600
23,660
27,200
9.0
^,600
27,100
314»0
lOJ
^f*
26,300
28,930
33,300
11.4
H
29,600
32,460
37,300
12.7
33,000
36,300
41,750
14.3
36,600
40,160
46,175
15.8
lA
40,000
44,000
50,600
17.2
1|
44,000
48,400
65,660
1&8
V<
48,200
63,000
60,960
3DL4
n
62,600
67,760
66,400
£i2
^A
67,000
62,700
72,100
3i.O
If
61,700
67,870
78,060
2B.7
H^
66,600
73,160
84420
3816
If
71,600
78,760
90,576
3L0
Safe working load sliould be about one-half of proof tost.
The breaking strain is about double the proof test.
LUBRICATION. 1497
"Wlien two bodies are compelled to move, one upon the other, the reilit-
— ^ encountered is called friction, of which we have three kinds: roUinc
sliding of solids, and fluid friction of liquids and gases.
Xbe reduction of friction and its consequent generation of heat is accom-
puslied to a large extent by the use of lubricants.
Xhurston says the characteristics of an efficient lubricant must be r
1. Enough " body " or combined capillarity and viscosity to keep the sur-
f luses between which it is interposed from coming in contact under maxi-
mum pressure.
2. The greatest fluidity consistent with the preceding requirements.
3- The lowest possible co-efficient of friction under the conditions of
aetual use, I.e., the sum of the two components, solid and fluid friction
should be a minimum. '
4. A maximum capacity for receiving, transmitting, storing, and carryins
away heat. ' *
5. Freedom from tendency to decompose, or to change in composition by
summing or otherwise, on exposure to the air while in use.
6. Entire absence of acid or other properties liable to produce Injury of
materials or metals with which they may be brought in contact.
7. A high temperature of evaporization and of decomposition and a low
temperature of solidification.
8. Special adaptation to the conditions as to speed and pressure of rubbing
■orfaces under which the unguent is to be used.
9. It must be free from grit and all foreign matter.
AU AnintAl or Vefpetable Oila eventually decompose, and become
gummy, and retard the speed of any machine to which they may be applied.
Btfneral Oils — which are used in steam and electrical engineering—
do not absorb oxygen, and do not take fire spontaneously, as do the animal
and vegetable oils.
Orrasga have their proper place, as in railroad oar axles, and in caps
feeding Journals that do not require lubrication until a certain predeter-
mined temperature has been reached, for which the grease to be used is
suited.
Vegr«ital>l« Oil* should not be used In any place from which there is
any prospect of their being taken to the inside of a steam boiler, as they
materially encourage corrosion and pitting of boiler shells.
W^«telit of OH p«r Clalloii. The Pennsylvania Railroad specifica-
tions call for these approximate weights : Lard oil, tallow oil, neatsfoot oil,
bone oil, colza oil. mustard-seed oil, rape-seed oil, paraffin oil, 600 degree fire
test oil, engine oil, and cylinder lubricant, 7^ pounds per gallon.
Well oil and passenger car oil 7.4 lbs. per gallon.
Navy sperm oil 7.2 " " "
Signal oil 7.1 " " "
300 degree burning oil 6.9 " " "
150 d^^ee burning oil 6.6 '* '* "
In many of the large power plants the lubrication of a large proportion of
the bearings is controlled by a system which pumps the oil Uirough pipes to
bearings, and after its use, it is drained to a central point there to be filtered,
and foreign matter eliminated, and then used over again.
Lubrication is more apt to be overdone than to be neglected to damage of
machinery.
1498 LUBRICATION.
B««t ItaterlcAMte for Different
(Thuraton.)
Low temperatures, m In rock drills ) , ,_ka --,i„«--i i„K*4.»««4n<r ^n.
driven ty compr^ed air . . . .) Wght mineral lubricating oik.
Very great pressures, slow speed . . { ^™f^JJfi^^*^°* *"** ******* •**
Heavy pressures, slow speed . . . {The aboro^lard and tallow ««!«««
Heavy pn^sures. high speed . . • { ^^^Sii^ ouS.*^'"*"' "^ ""^
Light pressures, high speed . . • {^^V^i^r^^J^'^]!^^ ^
I Lard oil, tallow oil, heavy miaenl
oils, and the heavier vegeUfet*
oils.
Steam cylinders Heavy mineral oils, lard, taDov.
watches and other delicate mech- | ^^'2S?2,rJ^r^£aTJSS
For mixture with mineral oils, sperm is best ; lard is much used; olireaai
cotton-seed oils are good.
PAUrTIlVCl.
After making a series of exposure tests to ascertain the efficiency of ksd
and zinc paints, G. R. Henderson, N. & W. Railroad, reaches the lollovii^
conclusions.
Tin* — The best results were obtained with the first coat white lead, and
second coat, white zinc. The second coating of zinc gave generally the bat
results, and the second coating of lead the most.
C^alvanlsed Mrota* — The same remarks apply to galvanized iron is
given for tin.
Slieet Iron. — The mixture of one-third white zinc and two-thirds vhJt«
lead, for both coats, gave the best results on this material, and, in genenl,
the zinc pfdnt gave better results than the lead paints.
Poplnr. — The second coats of zinc showed up well on poplar, no nuUttf
whether the priming coats were white lead or white zinc, or mixed leadsztf
zinc. The lead second coating Miowed up the most on this material, bat is
each case where the second coat was of zinc, totally or partially, the fti^
was in a perfect condition.
IVIilte Pine. — Tlie same remarks apply to white pine as to poplar.
Yellow Pine. — This material seems to be difficult to properly ttttX
with paints ; the best results were obtained with the first coat m lead,as<l
the second coat of lead and zinc mixed. Where the first coat was of le*')
and zinc mixed or entirely of zinc, the results were poor throughout, vbidi
seems to indicate that as a general thing the lead la better for priniii^ oa
this material.
Conclnalon. — Lead priming and zinc coating are generally good fiff
tin, galvanized iron, poplar and white pine. Sheet iron shows up Mst vitk
both coats of mixed paints. Yellow pine appeared beat with the first eoSt
of lead and the second coat of lead and zinc mixed.
Comparing the materials which were painted, we find that, generally, pop*
lar retains the paint better than white pine; and would therefore, be pi«'
ferred for siding on buildings, etc. Yellow pine aeema to be the worst d
all for this pun)ose. Black iron as a whole retains the paint better tbiv
either tin or galvanized iron.
^
MISCELLANEOUS TABLES.
1499
MISCELLANEOUS TABLES.
lim«BITS Alfll IHlfiAfllTltKS.
IHcaawre of Capacltj.
illoB. — The standard gallon measures 231 oublo inches, and contains
B22 pounds avoirdupois = 68372.1757 grains Troy, of distilled water, at
I xnaxlmum density 39.83^ Fahrenheit, and 30 inches barometer height.
:^Bns]iel. — The standard bushel measures 2150.42 cubic inches =77.627413
»«uads avoirdupois of distilled water at 39.83^ Fahrenheit, barometer 30
icliea. Its dimensions are 184 inches inside diameter, 19^ inches outside,
Ad 8 inches deep ; and when neaped, the cone must not be less than 6
kd&es high, equal 2747.70 cubic inches for a true cone.
. — The standard pound avoirdupois is the weight of 27.7016 oubio
&cti«6 of distilled water, at 39.83° Fahrenheit, barometer 30 inches, and
eisl^^ iA t^d air.
Meafiare of IteBctli.
Miles.
Furlongs.
Chains.
Bods.
Yards.
Feet.
Inches.
\
8
80
320
1760
5280
63360
0.1^26
1
10
40
220
660
7920
0^125
0.1
1
4
22
66
792
OJ008126
0.025
0.25
1
5.5
16.6
198
0.00066818
0.0O15454
0.045454
0.181818
1
3
36
O.OO018930
0.00151516
0.01515151
0.0606060
0.33333
1
12
0.000015783
0.000126262
0.001262626
0.00505060
0.0277777
0.083333
1
]!IIe«»«r« of Snrfitce.
8q. Miles.
Acres.
S. Chains
Sq. Rods.
Sq. Yards
Sq. Feet.
Sq. Inches
1
640
6400
102100
3097600
27878400
4014480600
0-0011562
1
10
160
4840
43560
6272640
O.00O1562
0.1
1
16
484
4356
627264
0.000009764
0.00625
0.0625
1
30.25
272.25
39204
0.000000823
0.0002066
0.002066
0.0330
1
9
1296
0X1000000358
0.00002296
0.0002296
0.00367
0.1111111
1
144
O.OQO00000025
0.000000159
0.00000159
0.00002652
0.0007716
0.006944
1
Meitaare of C»pacttj.
Cub. Yard.
Bushel.
Cub. Feet.
Pecks.
Gallons.
Cub. Inch.
1
21.6962
27
100.987
201.974
46656
0.03861
1
1.24445
4
9.30918
2160.42
O.OS7097
0.803564
1
3.21425
7.4806
1728
0.009269
0.25
0.31114
1
2.32729
637.606
0.107421
0.133681
0.429684
1
231
O.0O0547
0.001860
0.004329
1
1500
MISCELLANEOUS TABLES.
^
Measare of I«li|iiUU.
Gallon.
Quarts.
Pints.
Oills.
Cab. IneftL '
1
0.25
0.125
0.03125
0.004329
4
1
OJS
0.125
0.17316
8
2
1
0.25
0.09463
32
8
4
1
0.13858
231
1
Measiirai of IVelclits.
AVOIRDUPOIS.
Ton.
Cwt.
Pounds.
OnncA.
I>rvBS.
1
20
2240
36840
573»
0.05
1
112
1792
SSSR
0.00044642
0.0088285
1
16
S6
0.00002790
O.000IS58
0.0625
1
»
0.00000174
0.0000348
0.0016
0.0626
1
TROY.
Pounds.
Ounces.
Dwt.
Grains.
Poimd A^tsi,
1
0.083333
0.004166
0.0001736
1.215276
12
1
0.06000
0.002063333
14.58333
240
20
1
0.0416666
291.6066
9760
480
24
1
7000
QJSS9SI
QjOGSSn
0.0C9t»
aoooi«85
1
APOTHECARIES.
I
Pounds.
Ounces.
Drams.
Scruples.
QraiBK.
1
0.06333
0.01041666
0.0034722
0.00017361
12
1
0.125
0.0416666
0X020833
96
8
1
0.8333
0.016666
288
24
3
1
0.06
480
60
96
1
Eqiilval«nte of JLtineal
MoaMiri
M — Motrical wuaA 1
Sm***-
Meters.
English Measures.
Inches.
F«el.
Yards.
MI]»
Millimeter . ,
Centimeter
Decimeter . .
Meter
Decameter
Hectometer
Kilometer .
Miriameter
, uim
, cm
.001
.01
.1
1.
10.
100.
1,000.
10,000.
.039371
.393708
3.937079
J9.37979I
jOttfiSl
.082809
.328068
3.Z8i89f
32.80809
328.0699
3280.8B9
.001094
J010686
.100983
lojnesa
109.8633
1003.633
.....
6J13SI
Micron = .000,001 meter
=: .001 millimeter.
MISCBLLANBOUS TABLBS.
1501
|«lv-al«Bto of X4Mcal Mcasares — Met. and Sac
.^OmHnued.
English Measures.
Meters.
Reciprocals.
Kill
.02539954
.3047945
^143836
5.029109
20.11644
1609.3149
98.37079
ffiAhftfsrrl foot
3.280699
Bftt r-z 1 yard .............
1.093633
yard8=i6| f eet=l rod or pole ......
oles — 66 feet •— 22 yards — 1 cliain (Ganter's)
chains — 320 poles — 5280 ft — 1760 yds. — Imlle
.1988424
.0497106
.00062138
1 Guiit«r'8 chain has 100 linlcs. Bach linlc = 7.92 inches = 0.2017 meter.
lalvalemta
of Aaporfldal Moaanrea— Metrical
(MBTBICAL AlTD SNOLISH MEA8UBK8.)
aad Bag:.
Qliare . . ~
aitiare=8q.met
Miare . . .
•
Msare (not used)
OCvcaa G • • •
luare kilometer
Square
meters.
.1
1.
10.
m.
1000.
10000.
1000000.
English Measures.
Square
inches.
155.01
1550.06
15600.69
155MS.f
Square
feet.
1.076
10.764
107.64
H76.4
10764.3
107643.
Square
yards.
.119
1.196
11.960
llf.i033
1196.033
11960.33
Acres.
2.4711431
247.11431
English Measures.
iq-uareinch .
4 square Inches = 1 square foot .
iquare feet = 1 square yard . .
|Bq. yds. ) _ 1 perch = l square rod
7^ sq. f t. ) or pole
?^^^}=''-"
10 acres = 1 square mile ....
Square
miles.
,386126
Metrical Measures.
6.461367 sq. cent.
.09289968 sq.mt.
.8360972 " •*
25.29194
4046.711
2589894^
II ti
II II
II II
Beciprocals.
.1660069
10.7642996
1.196033
.0996383
.00024711
.00000038612
Sqalvaloats of IVelrlite
—Metrical aad Cagrllsii.
Grammes
English Weights.
Oz.
avoir.
Lbs.
avoir.
Tons
2000 lbs.
Tons
2240lb8.
Troy
weight.
EilliKramme . •
Centigramme .
^igramme .
riaas • • •
decagramme .
rect^ramme .
kilogramme .
lyruun'amme .
tulntal . . .
lillier or Tonne
.001
.01
.1
1.
10.
100.
1000.
10000.
100000.
1000000
• • « •
• • • •
• • • ■
.0353
.3527
3.5274
35.2739
352.7394
3527.3943
• • • •
• • • •
• • • •
• • • •
MZ2
.02205
.22046
2.2046
22.0462
220.4261
2204.6215
.001102
.011023
.110231
1.102311
.(M)6984
.009842
.098421
.984206
.015 Grs.
.15 "
1.643 "
15.43235'*
.... ox.
32.150727"
321.507266"
3215.07266 "
32150.72665"
English Weights — " ATolrdupoie
I."
Grammes.
Reciprocals.
grain
4.34375 grains zr 1 dram
6 drams = 1 ounce = 437.5
6 ounces = 1 pound = 7000
OOlbs. — 1 cwt. CAmerlcan;
12 lbs. =:lcwt. (English) .
0 cwt. — 1 ton (Am7\ In kili
• • • •
• •
.0G479895
1.771836
28.349376
453.592652
45369.265
60602.376
907.18524
1016.04753
.06479896
1JS56175
SiinuM
15.43234875
JS64383
grains
grains
1 . . . .
t •
• •
.0352738
.00220462
.000022046
.00001968
)S • . .
.001102311
0 cwt. = 1 ton (£
English Well
i grain ....
M grains = 1 dw<
W owt — 1 ox.
Ing.) in kil
jhts — "Ti
• • • •
OS . . .
roy."
. • . *
• •
.000884206
15.43234875
.6430146
-JWiKftra
i2o*.=iib. . . . .' ; .
37
3.241964
.00267923
XISGELIuiNEOUS TABLES.
i
1
1
a
::.-::i5l|
St
;»lii:
.a
ii
%
iWgll:;
4
iiiii|:;
ii
4
i^m^
^.iilin;
^x
ii
:;:'-.i
1
'"-Sir
E
^^Hill
!
iiijjir
i
f
|i»ii
s .
i. -.
1
1 !
iiiiiii
3 ;
1
:::;|:l:
^
•Ei
&
111
III
. ii
l\
'.:i
MISOBLLAKSOUB TABLES.
1
1603
[«4rlc«l Measures Sqalvalent to ■■cli*l> Measvrea.
Meters.
Inches.
Feet.
1-/-
0.039
0.0033
2
0.079
0.0066
3
0.118
0.0008
4
0.167
0.0131
6
0.197
0.0164
6
0.236
0.0197
7
0.276
0.0230
8
0.315
0.0262
9
0.364
0.0295
1(^/. = !./«
0.394
0.033
2
0.787
0.066
3
1.181
0.008
4
1J>75
0.131
6
1.969
0.164
6
2.362
0.197
7
2.766
0.230
8
3.160
0.262
9
3.543
0.295
10t/« = .!■
3.937
0.328
.2
7.874
0.666
•3
11.811
0.984
.4
16.748
1.312
.5
19.686
1.640
.6
23.622
1.969
.7
27.660
2.297
^
31.497
2.625
.9
35.434
2.963
1-0
39.371
3.281
Table for tlie CosYersloa of Mils. (I-IOOO lacliea) iato
Ceatimeters.
Centi-
Centi-
Centi-
Centi-
Mils.
meters.
Mils.
meters.
Mils.
meters.
Mils.
meters.
1
.00254
18
.04671
35
•Uoooo
62
.1321
2
.00608
19
.•04825
36
.09142
63
.1346
3
.00762
20
.06079
37
.09396
54
.1372
4
.01016
21
J06333
38
.09650
66
.1397
6
.01270
22
.06587
39
.09904
66
.1422
6
.01624
23
.05841
40
.1016
67
.1448
7
.01778
24
.06095
41
.1041
68
.1473
8
.02032
26
.06348
42
.1067
69
.1499
9
.02286
26
.06602
43
.1092
60
.1624
10
.02540
27
.06856
44
.1118
61
.1649
11
.02793
28
.07110
46
.1143
62
.1676
12
.09047
29
.07364
46
.1168
63
.1600
13
.03301
30
.07618
47
.1194
64
.1626
14
.03656
31
.07872
48
•1219
65
.1651
16
.03809
32
.06126
49
.1246
66
.1676
16
.04063
33
.06380
50
.1270
67
.1702
17
.04317
34
.08634
61
.1296
68
.1727
r
1604
MISGBUiAKBOUS TABLB8.
OTaMe f»r tke Goaveralim m£ Mils. — OmttiiiMd.
Centl-
Centi-
Centi-
Cecd-
Mih.
meters.
Mils.
meters.
Mils.
meters.
Mils.
metars.
69
.1752
77
.1956
85
.2150
9?
.-2362
70
.1778
78
.1981
86
.2184
94
.3387
71
.1808
79
.2006
87
.2209
96
J»Vi
72
.1829
80
.2032
88
.2236
96
.2tiS
73
.1854
81
.2057
89
.2280
97
.St«5
74
.1879
82
.2083
90
.2286
98
:M89
76
.1906
83
.2106
91
.2311
99
.S5H
76
.1930
84
.2133
92
.2336
100
*•
Earllali lll«asav«« JEqiiivalem* «• Hetricttl lllcaai
«
•
m,
5
s
e
e
u
s
ja
2
•
4*
s
«»
&
s
B
w4
^•4
•
1
9
1
5
•-4
^
0.794
1
0.0254
0.01
.003
10
3JI8
JL
1.588
2
.0608
0.02
.006
20
€iW
JL
2.381
3
.0762
0.08
X09
90
9.144
Y
3.176
4
.1016
0.04
.012
40
12.193
JL
3.969
6
.1270
0.06
.015
60
15.SI0
1
4.762
6
.1524
0.06
.018
eo
18J88
JL
6.566
7
.1778
0.07
.021
70
2LaK
\
6.360
8
.2032
0.06
.024
80
24JS1
JL
7.144
9
.2286
0.09
.027
90
27.4a
V
7.937
10
.2540
.1
.030
100
30.419
If
8.731
11
.2794
.2
.061
200
msu
y
9J>26
12
.3048
.3
.091
300
9i.4as
ii
10.319
.4
.122
400
121 .918
i
11.112
£
.152
500
15SJ97
11.906
.6
.183
600
iffijen
Y
12.700
.7
.213
TOO
21X351
»
13.494
14.287
16.061
15.876
16.668
17.462
18.266
19X»0
19.843
20.637
21.430
22.224
.8
.214
800
24S.836
X
.9
.274
900
274JI5
?
1.0
2
3
4
6
6
7
8
9
10
.305
.610
.914
1.219
1.524
1.829
2.134
2.438
2.743
3.018
1000
304.7M
1
23.018
I
23.812
1
24.606
26.400
MISCBLLAKSOUS TABLES.
1505
^
G4»BTei9ft«a of iMChes
« KlirbtlM into DeciMaU of
Foot.
-
Fractions of an Inch.
luclieB.
0
i
\
1
i
t
i
1
0
.0000
.01041
.02083
.08126
.04166
.06206
.0626
.07291
1
.08333
.00375
.10416
.11468
.126
.13641
.14688
.16639
2
.16666
.17707
.1876
.19792
.20632
.21873
.22914
.23965
3
.25
.26011
.270
.28126
.29166
.30208
.3126
.32291
4
.33333
.34376
.36416
.364
.376
.38641
.39688
.40639
5
.41666
.42707
.437
.44792
.46832
.46873
.47914
.48966
6
.6
.61041
.620
.63125
.54166
.55208
.5626
.57291
7
.58333
.68376
.60416
.614
.626
.63541
.M688
.66639
8
'MMm
.WQDO
.67707
.685
.09792
.70832
.71773
.72914
.73966
9
.76
.76041
.770
.78126
.79169
.80206
.8426
.82291
10
.83333
.84376
.86416
.864
.876
.88541
.89688
.90639
11
.91666
.92707
.937
.94792
.96832
.96873
.97914
.96966
12
Ifoot.
foot.
foot.
foot.
foot.
foot.
foot.
foot.
A in.
z=z 0.006208 ft ; ^\u.z= 0.00266 ft. ; ^
In.
= 0.001375 ft.
A
c
Alpha.
N
V
Nu.
B
^
B«ta.
B
i
Xi.
r
I
Gamma.
0
o
Omicron.
A
Delta.
n
w
Pi.
E
«
Bpallon.
p
p
Rho.
z
i
Zeta.
2
a-
f Sigma.
H
i|
£ta.
T
T
Tau.
e
$
Tbeta.
Y
V
Upelloa.
Phi.
1
I
Iota.
♦
«
K
K
Kappa.
LamDda.
X
X
Chi.
A
A
♦
4^
Psi.
M
It-
Mu.
n
M
OmSga.
AlfOlJliiAR VCIiOCITir.
The number of degrees per second through which a body revolves about a
center.
tr = 2r n
vbere
n= revolutions per second
IT = angular velocity.
FRICTlOIf.
The following laws of friction are only approximate, the tirst not being
true where pressures are very great, and the third beyond a velocity of 160
feet per minute.
1. lection varies directly as the pressure on the sur races in contact.
2. Jfrictionis independent of the extent of the surface in contact.
3. Friction is independent of the velocity ^ when the surfaces are M motion.
4. Rolling friction varies directly as the pressure, and inversely as the diam-
eter of the rolling bodies^ where the cylinders and balls are of the same
substances, and are pulled or pushed ^ as in a car or wagon.
Where the road is propelleaby a crank fixed on the axle, the law is
reversed.
1506
MISCWiLAKBOUS TABLTS8.
VKMPSlftAYirRB, or mnTKHSKnc OV MKAT.
Standard PoiBtB— FaJirenbeU, CenUgrade. 'B4nnm
Boiling point of water under 1 __ 2129 IVP W*
one atmosphere ... .J ^^^ „ ^
Melting point of ioe . . . . 329 (F •*
(Abeolnte «ero; known by\ — -aWv^t^-Afiio^ —2740 —213^^
theory only J »w^»«v
90 Fahrenheit = C9 Centigrade =: 49 Kteumur.
TempFah. = | Temp. Cent.-VS39 == | Temp. Wan, + 38^
Temp. Cent. = | (Temp. Fall. ~ 329) = ^ Temp.KAan,
4 4
Temp. R4au. = ^ (Temp. "Fah. — 339) = ^ TeTnp.O«a^
T»ble of Cooiparis«»a^ ^^ Iftiffovomt TH^
R6au. \ Cent
,.\ Fall. \B4att-\Cwi.
e5.7 \
82.2 1
Q5.3 \
81.6
e4.8
81.1
e4.4
803
64.0
80.0
03.6
79.4
63.1
78.8
62.6
78.8
62.3
T7.7
61.7
77.2
61.3
76.6
60.8
76.1
60.4
76.6
6O.0
75.0
69.6
74.4
68.1
73.8
68.6
73.3
68.2
72.7
67.7
72.2
67.3
71.6
66.8
71.1
66.4
70.6
66.0
70.0
66 JS
69.4
66.1
68.8
64.6
68.3
64.2
«7.7
68.7
67 Jt
63.3
66.6
62.8
66.1
62.4
66.6
62.0
66.0
MISOXXLANBOnS TABLES.
1607
^PwMi9 «f COMl
Mirtiwa
imfMHWrnwrnt
tommmim
twrn*^ QmHnued,
Fall.
R^u.
Gent.
Fab.
Bteu.
Cent.
Fah.
IMaa.
Cent.
lie
•
37.3
46.6
70
16.8
21.1
24
—3.6
-4.4
116
36.8
46.1
60
16A
20.6
23
—4.0
— 6i)
114
36.4
46.6
68
16.0
20.0
22
-4.4
— 6J5
113
36.0
46.0
67
1&£
19.4
21
—4.8
-6.1
112
XJH
44.4
06
16.1
18.8
20
—5.3
—6.6
111
36.1
43.8
66
14.6
18.3
19
-^.7
—7.2
110
34.6
43.3
64
14.2
17.7
18
-«.2
—7.7
109
94.2
42.7
63
13.7.
17.2
17
—6.6
—8.3
106
33.7
42.2
62
13.3
16.6
16
—7.1
—8.8
107
83.3
41.6
61
12.8
16.1
16
— 7JJ
— 0J5
106
32.8
41.1
60
12.4
15Ji
14
—8.0
—10.0
106
32.4
40.6
69
12.0
16.0
13
—8.4
—10.6
104
32.0
40.0
68
11.6
14.4
12
-8.8
—11.1
108
31.6
39.4
67
11.1
13.8
11
-4>J^
—11.6
102
31.1
38.8
66
10.6
13.3
10
—9.7
—12.2
101
30.6
383
66
10.2
12.7
9
—10.2
12.7
100
30.2
37.7
64
9.7
12.2
8
—10.6
—13.3
99
29.7
37.2
63
9.3
11.6
7
—11.1
—13.8
98
29.3
36.6
62
8.8
11.1
6
—11J5
-14.4
97
28.8
36.1
61
8.4
lOUS
6
—12.0
—16.0
96
28.4
d6A
60
8.0
10.0
4
-12.4
—15.6
96
28.0
36.0
49
7.6
9.4
3
—12.8
T-16.1
94
27.6
34.4
48
7.1
8.8
2
—13.8
—16.6
93
27.1
33.8
47
6.6
8.3
1
—13.7
—17.2
92
26.6
83.3
46
6.2
7.7
0
—14.2
—17.7
91
26.2
32.7
46
6.7
7.2
—1
—14.6
—18.3
90
25.7
82.2
44
6.3
6.6
—2
—16.1
-18.8
89
25.3
81.6
43
4.8
6.1
—3
— 16JS
—19.4
88
24.8
31.1
42
4.4
6A
—4
—16.0
—20.0
87
24.4
30.6
41
4J0
6.0
—5
—16.4
-20.6
86
24.0
30.0
40
3JS
4.4
—6
—16.8
—21.1
86
23.6
29.4
39
3.1
3.8
—7
—17.3
—21.6
84
23.1
28.8
38
2.6
3.3
—8
—17.7
—22.2
83
22.6
28.3
37
2.2
2.7
—9
—18.2
—22.7
82
22.2
27.7
86
1.7
2.2
—10
—18.6
—23.3
81
21.7
S7.2
86
1.3
1.6
—11
—19.1
—23.8
80
21.8
26.6
34
0.8
1.1
—12
-19.6
—24.4
79
20.8
26.1
33
0.4
0.6
—13
—20.0
—26.0
78
20.4
26.6
32
0.0
0.0
—14
—20.4
-25 J»
77
20.0
26.0
31
-0.4
-^JS
—16
—20.8
—26.1
76
19.6
24.4
30
-0.8
—1.1
—16
—21.3
—26.6
76
19.1
23.8
29
—1.3
—1.6
—17
—21.7
—27.2
74
18.6
23.3
28
—1.7
—2.2
—18
—22.2
—27.7
78
18.2
22.7
27
—2.2
—2.7
—19
—22.6
—28.3
72
17.7
22.2
26
—2.6
—3.3
—20
—23.1
—28.8
71
17.3
21.6
26
-3.1
-3.8
Tlwumlb^r of l^«CT«<Ni Ccat. =
= IVm
liber of I^ofrrooa I^b.
Tenths of a Degree— Centigrade Scale.
Degrees
Cent.
.0
.1
.9
.3
.4
.5
.6
.7
.8
.9
Fah.
Fkh.
Fah.
Fah.
Fah.
Fah.
Fah.
Fah.
Fah.
Fah.
0
0.00
0.18
0.36
0.64
0.72
0.90
1.06
1.26
1.44
1.62
1
1.80
1.98
2.16
2.34
2.S6
2.70
2.88
3.06
3:24
3.42
3
3.60
3.78
3.96
4.14
4.32
4.50
4.68
4.86
6.04
6.22
8
6.40
6.68
6.76
6.94
6.12
6.30
6.48
6.66
6.84
74n
1508
MISCELLANEOUS TABIiBS.
ah. — (Qmtinued.)
Degren
Cent.
4
5
6
7
8
9
Tenths of a Degree — Centigrade Scale.
. i
.0
.1
.8
.3
.4
J(
jS
.7
Pah.
Fah.
Fah.
Fah.
Fah.
Fah.
Fah.
Fah.
7.20
7.38
7M
7.74
7.92
8.10
8.38
8.46
9.00
9.18
9.36
9.54
9.72
9.90
10.06
10.S6
10.80
10.98
11.16
11.34
11.52
11.70
11.88
12.06
12.60
12.78
12.96
13.14
13.32
13J50
13.68
13.86
14.40
1AM
14.76
14.94
15.12
15.30
15.48
15.66
16.20
16.38
16JS6
16.74
16.92
17.10
17.28
17.46
I
Fab..'Fkh.
&6Cl
10.44
12.34 ne
14jOI IkS
15.M icje
17.64 UJS
nruBiiMr of D«rr*«« '
ttk« =
:Timm
iber of 1^
Bcrv*
m Cmmu
Ten ths of a Degree — Fahrenheit Scale.
Degrees
1 t
.0
.1
.9
.3
.4
.5
^
.7 1 ^ 1 .9
Cent.
Cent.
Cent.
Cent.
Cent.
Cent.
Cent.
C«nt.
1
Cent.; Cesi.
0
0.00
0.06
0.11
0.17
0.22
0.28
0.33
0J»
a44 05B
1
0.56
0.61
0.67
0.72
0.78
?3
0.89
OJH
IjQOl IJS
2
1.11
1.17
1.22
1.28
1.33
1.44
IJEO
1.56 1 1.61
3
1.67
1.72
1.78
1.83
1.89
1.94
2.00
2.06
2.11 2-n
4
2.22
2.28
2.33
2.30
2.44
2JS0
2.66
2.61
3,67 2.12
5
2.78
2.83
2.89
2.94
3.00
3.06
3.11
3.17
3.32 ' 3A
6
3.33
3.39
3.44
3JS0
3.56
3.61
3.67
3.T2
3.T8 3J3
7
8.89
3.94
4.00
4.06
4.11
4.17
4.23
4.28
4.33 4J»
8
4.44
4M
4JM
4.61
4.67
4.72
4.78
4.83
4.89 i 4JI
9
5.00
5.06
5.11
6.17
5.22
5.28
5.33
6.39
6.4ft 5Ji
1
C«eflcteMts of ExpianaloB at OHUwkakty Veatperatv
(Solids.)
Material.
Coefficient of KTpaiwinB
OF.
Alnminnm
Brass •
Briok
Bronze
Cement and ) from
Concrete ) to
Copper
Q1M» ''To
Gold
Qranlte
Iron, cast
Iron, wrought
.0000114
JOOOOWt
.00000306
.0000100
.0000066
.ooQQore
JOOOOOSSl
aa
J000Q0631
.00000041
UMN10046
.00000667
.00000677
jooma
JOOOBOBU
jOOOOISO
UWOQIO
JBMM
4M)001T3
jO0Mg7g
J0O0M838
jQOOOlSl
J0000106
JOOOOIS
1
MISCflLLANXOUS TABIJE8.
1509
C««flct«Mte •r mspmmmimm—iOontinued.)
Material.
Coefficient of Expansion.
Ltoad
Mmrble (average) . «
Idjuonry ''°^
PlaHnum
Porcelain
S&ndatone ''<>™
Stiver
Slate
Steel, antempered
Steel, tempered
Tin
l^ood (pine)
Zinc
.0000168
.000004
.0000026
.0000019
.00000494
.0000020
.0000040
.0000067
.0000106
.00000D6
.00000611
.00000680
.0000116
.00000276
.0000163
.0000284
.000007
.0000017
.0000088
.OOOOOSOO
.0000096
.0000070
.000012
J0000194
J0OO01Q2
.0000110
.0000124
.0000200
J00000486
.0000293
HBAT.
•peclflc Keat of SvlMtaMCMi.
The tpecific heat of a body at any temperature i» the ratio of the quantity
of beat required to raise the temperature of the body one degree to the
quantity of heat required to raise an equal mass of water at or near to its
tamperature of maximum density (4°C. or 39.2oF.) through one degree.
SpecUic Heat* of Motals*
(Tomlinson.)
MeUl.
Aluminum . . ,
Copper . . . .
German Silver ,
Iron ....
Lead
Platinum . . .
Platinum Sliver
Silver ...
Tin ....
Zinc ....
Specific Heat at
(PC. or SSPT.
0.2070
O.OOOl
0.0941
0.1060
0.0300
0.0320
0.0473
0J0M7
0.0623
0.0901
60PC.orl22OF.
0.2185
0.0923
0.0047
0.1130
O.0316
0.0326
0.0487
0.0609
0.0668
0.0838
100oCor212OF
0.2300
0.0006
0.0062
0.1200
0.0331
0.0333
OJOSOi
0.0691
0.0696
0.0976
BKoiaa ftpoctflc Hoat of PlattMom.
(Pouillet.)
Between 0°C. (32or.) and 100°C. (2120F.)
, . 0.0336
'• " •' " 300°C. (572*^F.)
. . 0.0343
«« " " " 600OC. (932<'F.)
. . 0.0362
M «« «* u 700OC. (12920F.)
. . 0.0360
•• " *■ ♦• lOOO^C. (18320F.)
, . 0.0373
M i< «« u iaOO°C. (21920F.)
, . 0.0882
JUBOKLLAHKOUH
"S?sbsl3S33!3;-S!iisi : : : :!iliiil!i
oiiiiiiiliii^iiii :
ilHllilllllillilli
II—
i!5
lilisiiHiiililiili:
lllllilHIilliliiil::;
'a,
111
::::::: :|| : :5i := :
'9
;|:
I|l55lllt|||l2^i-| W%-
lii;S«-!-«i-i6;m-<ia!Bin«»o-<-«B' eCoSi
k
HISCKLLAKBODS TABIiBS.
1511
Mtan Specific Bleat <^ WaUr.
(Rognault.)
Bet ween 0^. (320F.) and 400C. (IO40F.) 1.0013
" 80°C. (17eoF.) , . . 1.0036
" laooc. (2480F.) 1.0007
♦• leOOC. (320OF.) 1.0100
" 2000c. (302«>F.) 1.0160
•« 230«>C. (44«oF.) 1.0204
Mean, Specific Heat of Glass (Kohlrausch) 0.19
• c
•«
«4
(t
ft
•4
<•
«4
•p«clflc Hea« of C»aii^« »ma Vapors at CoM«t«itt
Substance.
A.iT
Carbon monoxide
Carbon dioxide .
Hydrogen . . .
Nitrogen . . . .
Oxygen . . . .
Steam ....
Specific Heafc for
Equal.
OtwerTor.
YolumeB.
Weights.
0.2376
0.2375
Regnault
0.2370
0.2450
Begnault
0.2985
0.1052
Wiedermann
0.2359
3.4090
Regnatilt
0.2368
0.2438
Begnault
0.2406
0.2175
Begnault
0.2889
0.4806
Begnault
Total Heat of Steam.
Brltlab Tbenaal ITnIt 1 (B. T. U.) is the quantity of heat which
will raise the temperature of one pound of water one degree Fah. at or near
Its temperature of maximum density 39.1®.
Froacli Calorie: is the quantity of heat that vlll raise the tempera-
ture of one kilogramme of pure water 1^. at or near 4^\
Poand Oalorlo : is the quantity of heat that will raise the tempera-
tare of one pound of water 1°C.
1 B. T. U.
1 Calorie ;
1 lb. Calorie :
1 pound Calorie :
: .252 Calories.
: 3.968 B. T. U.
2.2046 B. T. U.
I Calorie.
Xhe Mechanical Kqaivalent of Heat.
Jonle gives
Professor Rowland,
IB. T. U. = 772ft.lbs.
1 B. T. U. = 778 ft. lbs.
1 ft. lb. = ^ = .001285 B. T. U. per minute.
1 H. P. = 42.416 B.T.U.
(See Table of Eneruj Eqaivalents on p. 1258.)
1512
MISGRLLAITBOUS TABLES.
•p«ciflc C^mvltj.
Names of Sub-
Atances.
Oodar, Indian .
** American
Citron ....
Cocoa-wood . .
Cherry-tree . .
Cork
CypreM, Spanisli
BDony, American
« Indian .
Elder-tree . . .
Elm, trunk of .
Filbert-tree . .
Fir, male . . •
" female . .
Hazel ....
Jasmine, Spanish
Juniper-tree . .
Lemon-tree . .
Lignum-vita . .
Linden^tree . .
Logwood . . ■
Mastic-tree . .
Mahogany . . .
Maple ....
Medlar ....
Mulberry . . .
Oak, heart of, 60 old
Orange-tree . .
Pear-tree . . .
Pomegranate-tree
Poplar ....
" white Spanish
Plum-tree . . .
Quince-tree . .
Sassafras . . .
Spruce ....
" old . . .
Pine, yellow . .
" white . .
Vine
Walnut ....
Yew, Dutch . .
•* Spanish .
Acid, Acetic . .
" Nitric . .
" Sulphuric .
** Muriatic .
" Fluoric . .
" Phosphoric
Alcohol, commer.
** pure
Ammoniac, liquid
Beer, lager . .
Champagne .
Cider ....
Ether, sulphuric
Kaptha . . .
Egg • • t •
Honey ...
Human blood
Milk ....
II
1.315
.561
.726
1.040
.715
MO
.644
1.331
1.209
.605
.671
.600
.550
.498
.600
.770
.556
.703
1.333
.604
.913
.849
1.063
.750
.897
1.170
.705
.661
1.354
.383
.529
.785
.706
.432
.600
.460
.660
J)64
1.327
.671
.788
.807
1.062
1.217
1.841
1.200
1.500
1.558
.833
.792
.897
1.034
.997
1.018
.739
flAA
.o*io
1.090
1-450
1.064
1.032
0476
0203
0263
0376
0259
0067
0233
,0481
0437
0252
0213
,0217
,0199
0180
0217
0279
,0^1
0254
0482
0219
0331
0307
0385
0271
0842
0324
0423
0255
0239
0190
0138
0191
0284
0255
0174
0181
mm
0239
0200
0480
0243
0285
0292
0384
0440
,0666
0434
0542
0663
0301
0287
0324
/)374
0360
0861
0267
0394
0524
0381
0373
Names of Substances.
Oil, Linseed . .
»• Olive . . .
« Turpentine
" Whale . .
Proof Spirit . .
Vinegar . . .
Water, distilled
sea . .
Dead Sea
Wine
Port . .
((
]nilacellaBe«as.
Ebonite
Pitch
Asphaltum ., |
Beeswax
Butter
Camphor .......
India rubber
Fat of Beef
Hogs
Mutton
Gamboge
Qunpowder, lootte ....
shaken . . .
it
if
solid
Qum Arabic . .
Indigo ....
Lard
Mastic ....
Spermaceti . .
Suffar ....
TaTiow, sheep .
" calf . .
♦• ox . .
Atmospheric air
Atmospheric air ....
Ammoniacal gas ....
Carbonic acid
Carbonic oxid
Carbureted hydrogen . .
Chlorine
Chlorocarbonous acid . .
Chloroprussic acid . . .
Fluoboric acid
Hydriodic acid
Hydrogen
Oxvgen ........
Sulphuretted hydrogen .
Nitrogen
Vapor of alcohol ....
'* turpentine spirits
" water ....
Smoke of bituminous coal
«• wood
Steam at 212P .....
JMO
.915
.870
SS2
.926
1.080
1.000
IJQ90
1.240
.992
.967
1.3
1.6
.906
1.650
ijQB14
JBBBl
.1K2
J9a
336
J92S
1.222
.900
1.000
1.550
1.80O
1.458
1.009
.947
1.074
.943
1.606
.924
.994
.923
.0013
JQ9S
SSBS
JOBK
JQMI
jam
iB3t
XOM
J048
JOSSL
jBsa
1.000
.500
Iii27
.972
.972
2ii00
3.472
2.152
2 371
4.346
,069
1.104
1.777
972
1.613
5j013
.623
.108
.90
.488
m»
.0331
co.ft.
'JO.
r.o
263.7
SOU
512.7
512.7
1316
I8SS
lUI
ISSO
2290
'3&3S
|58U
9370
512j0
851i)
2M3
33gJ0
53.80
474i)
957.3
r
^
MI80ELLANBOUS TABLES.
1613
O* ftPKCII'XC ORAVXTY AHD VIVIV
at 39.10 Fahrenheit = 4° Centigrade ; e2.426 poonds to the cubic foot
(authority, Kent, Haewell, and D. K, Chu-k).
▲Inminum, pure cast
" rolled
" *• anne'ld
•« nickel alloy, cast
" " " rolled
*• •• •« ann*ld
Aluminum Bronse, 10%
•• "6%
Brass, cu. 67, m. 33 caat
'* cu. eo, an. 40 "
Cobalt
Brass, plateg . .
nii^h yellow
Bronse oomjpoeitlon
cu. SO, tin 10
Bronxe composition
cu. 84, tin 16
Lithium • •
Potassium
Sodium . •
Rubidium .
Calcium . .
Magineeium .
Caesium . .
Boron • . .
Gluclnum
Strontium .
Barium . .
Zirconium .
Selenium . .
Titanium . .
Vanadium .
Arsenic . .
Columbium .
Lanthanum .
Niobium . .
Ehdymium .
Cerium . .
Antimony .
Chromium .
Zinc, cast . .
•» pure •
•• rolled .
Wolfram . .
Tin, pure . .
Indium . .
Iron, cast
•* wrought
•* wire
Steel, Bessemer
" soft .
Iron, pure .
Specific
Gravity.
2.56
2.68
2.66
2.85
2.76
2.74
7.70
8.26
8.32
8.405
8.60
• . . .
8.586
■ ■ • ■
OaOoB
• • « •
8.832
a67
0.87
0J97
1JS2
1.67
1.74
1.88
2.00
2.07
2.54
3.76
4.15
4.50
5.30
5.50
6.00
6.20
6.27
6.54
6.68
6.71
6.80
6.861
7.15
7.191
7.119
7.29
7.42
7.218
7.70
7.774
7.802
7.854
7.86
Authority.
P. B. C.
14
l(
i<
i(
(t
Kiche.
Haswell.
Thurston.
R.-A.
« • • • 9
P.B.C.
Thunton.
• • • . .
Haswell.
R.-A.
It
II
II
II
II
II
Haswell.
K.-A.
It
•I
II
Haswell.
li
R.-A.
ii
Haswell.
II
R.-A.
41
14
14
41
Haswell.
R.-A.
Haswell.
II
B.-A.
II
Kent.
44
Haswell.
14
Kent.
R.-A.
Lbs. per
Cubic
Foot.
160.63
167.11
166.86
178.10
172.10
170.85
480.13
515.63
519.36
524.68
530.61
....
535.38
• ■ • •
541.17
• » • •
561.34
36.83
54.31
00.55
94.89
98.01
106.62
117.36
124.85
129.22
168.56
234.09
269.06
280.91
330.85
343.34
363.95
374.65
387.03
391.40
408.26
417.00
418.86
429.49
428.30
446.43
444.40
465.06
463.19
460.08
480.13
485.29
479.00
489.74
490.66
Lbt». per
Cubic
Inch.
.0024
.0967
.0060
.1031
Al996
.0089
.2779
.2984
J006
.3036
.3071
• . . .
.3098
• • • •
.3132
.3191
.0213
.0814
.0360
.0648
.0667
.0629
.0679
.0723
.0748
.0918
.1355
.1499
.1626
.1915
.1987
JSMB
.2168
.2240
.2265
.2363
.2413
.2424
.2457
.2479
.2683
.2698
.2672
.2634
.2681
.2605
.2779
.2808
.2837
.2834
.2840
Kilos per
Cubic
Deem.
2JM
2.68
2.66
2.86
2.76
2.74
7.70
8.26
8.32
8.406
8.60
• . . •
8.586
» . . .
8.669
■ . . .
8.832
.57
.87
.97
lJi2
1.57
1.74
1.88
2.00
2.07
2.54
3.75
4.15
4.50
5.30
5JS0
5.67
6.00
6.20
6.27
6.54
&68
6.71
6.80
6.861
7.15
7.191
7.119
7.29
7.42
7.218
7.70
7.774
7.852
7.854
7.86
'Z/
1514
MISOELLANBOUa TABLBS.
OT APKCEVXC eMAVJCnr.-CbfUiiNMd.
Manganose . . • .
Cinnabar
Cadmium
Molybdenum . . .
Gun Bronze ....
Tobln Bronze . . .
Nickel
Copper, pure . . .
Copperplates and sheet
Bismuth
Silver
Tantalum ....
Thorium
Lead
Palladiimi ....
Thallum
Rhodium
Ruthenium ....
Mercury
Uranium
Tungsten
Gold
Platinum
Iridium
Osmium
Lbs. per
Cubic
Authority.
Foot.
R.-A.
499.40
Haswell.
505.52
R..A.
536.85
(t
536.86
Haswell.
546.22
A. C. Co.
523.06
R.-A.
548.34
i<
660.69
A. of C. M.
656.63
R.A.
611.76
((
657.33
II
674.19
CI
692.93
4*
709.77
<l
717.88
(1
739.73
II
765.34
II
766^
II
848.35
11
1167.46
11
1192.31
II
1206.05
14
1342.13
II
1399.57
41
1403.31
.2890
.2935
.3107
J107
.3161
.3021
.3179
.3186
.3222
.3540
.3806
.3902
.4010
.4108
.4154
.«81
.4371
.4429
.4909
.6765
.6800
■6979
.7767
.8060
.8121
Kilos per
CaMc
8Ji»
8jO
6.60
&:se
&»
9J0
lOA
lOJD
ll.»
11 J7
IIJO
IIJB
ISJD
12^
13J9
18.79
Authorities — R.-A. — Professor Roberts-Austen.
Haswell— Haswell's Engineer's Pocket Book.
P. R. C— Pittsbure Reduction Co.'s tests.
Kent — Kent's Mecnanical Engineer's Pocket Book.
Thurston — Report of Committee on Metallic Alloys of 17. S
Board appointed to test iron, steel, and other metals.
Thurston's Materials of Engineering.
Riche— Quoted by Thurston.
A. C. Co. — Ansonia Brass and Copper Co.
A. of C. M. — Association of Copper Manufacturers.
AliilJlUlVUM
AT e«o FAnjRiranaEXT
AXUHJOriJliA
Aluminum Commercially Pure, Cast " HS
Nickel Aluminum Alloy Ingots for rolling 2.«
♦' Casting Alloy J*
Special Casting Alloy, Cast .••;,••••••• JS
Aluminum Commercially Pure, as rolled, sheets and wire ..... ^»
t* «• • " Annealed *•»
Nickel Aluminum Alloy, as rolled, sheets and wire 2.*6
it " '* Sheets Annealed • • 2.44
Using these specific gravities, assuming water at 62 diwrees Fahraih^
and at Standard Barometric Height, as 62.365 lbs. per cubic foot (authonty,
Kent and D. K. Clark). ^^. . ^. , . .- «»o#wMtv-
Sheet of cast aluminum, 12 Inches square and 1 in«t!?V^l»'^"j^ JrSSifS*
Sheet of rolled aluminum, 12 inches square and 1 Inch thlck.w^ha 13.^^ lbs.
Bar of oast aluminum, 1 inch square and 12 inches long, wel^s I.IWS Ite.
Bar of rolled aluminum, 1 inch square and 12 inches long, w^hs 1.1606 Ite.
Bar of aluminum, cast, 1 inch round and 12 inches long, wei^ JK06 ids.
Bar of rolled aluminum, 1 Inch round and 12 inches long, weighs ^14 m»
^
XX)WBR RBQUIRBD TO DRIVE MACHINBRY.
SHOPS, ll^D TO DO VARIOUS KINDS
OP WORK.
wtioNr
2i
Fio. 1.
€k>n8taiit - ^ » .0001904.
Then
Hone-power » .0001904 X d x to x revelations per miniite.
Horse-Power S'oratnla*.
In an article byC. H. Benjamin in Bfarch, 1899, Machinery Bxe the follow-
Ins formulas for computing the horse-power required to operate tools, where
fr « weight metal removed per hour.
Ebcperiments with several lathes give:
H.P. - .036 W for cast iron.
H.P. ^ .067 W for machinery steel.
Ebmeriments with a Gray pkmer give:
H.P. — .032 W for cast iron.
Esroeriments with a Hendey shaper give
H.P. — .030 W for cast iron.
For milling machines we have:
H.P. - .14 W, for oast iron.
H.P. — .10 W for bronse.
H.P. — .30 TF for tool steel.
In eaoh case, the power required to run the tool, Kght, should be added.
JPower IJaod by HiMiamo-Xoola.
(K. E. Dinsmore, from the EUctriccU World.)
1. Shop shafting 2A In. x 180 ft. at 100 revs., carryiiur 26 pulleys
from 6 in. diam. to 36 in., and running 20 idle machme belts . 1.32 H. f
2. Lodge-Davis unrlght baok-geared drill-press with table. 28 in.
swing, drilling | in. hole In cast iron, with a feed of 1 in. per
minute 0.76 H. P.
3. Morse twist-drill grinder No. 2, carrying 26 in. wheels at 3200
revs 0.29 H. P.
4. Pease planer 30 in. x 36 in., table 6 ft., planing cast iron, cut
\ in. deep, planing 6 sq. in. per minute, at 9 reversals .... 1.06 H. P.
6. Shaping-machine 22 in. stroke, cutting steel die, 6 in. stroke, v
in. deep, shaping at rate of 1.7 square inch per minute . . . 0.37 H. P.
6. Engine-lathe 17 in. swing, turning steel shaft 2} in. diam., cut
A deep, feeding 7.02 in. per minute 0.43 H.P.
7. Engine lathe 21 in. swing, boring cast-iron hole 6 in. diam., cut
A diam., feeding 0.3 in. per minute 0.23 H. P.
8. sturtevant No. 2, monogram blower at 1300 revs, per minute,
no piping 0.8 H. P.
9. Heavy planer 28 in. x 28 in. x 14 ft. bed, stroke 8 in., cutting
steel, 22 reversals per minute 8.2 H. P
1616
1516 POWER REQUIRED TO DRIVE MACHINERY, ETC.
Power Required for MadUne Toola— Reselte ol
Xesto of V»rloes MacMme Toola.
(From a paper road by F. B. Duncan before the Engineers' Society of
Western Pennsylvania.)
EiNaiNB LATHSa.
16 in.; motor powo* required, approximate, 2 H.P. at fnaximiim.
18 in. X 6 ft.; motor power required, 2.1 H.P.
3d in. X 10 ft.; motor power required, 10 ILP.
PlANBBB.
10 X 10 X 20 ft. ; 8 tools, f X ^ in. cot; cutting q>ead, 18 fL; phaiic
40-ton iron casting. H.P. requirea for cut, 26.5: tor return. 23.6; for n-
verse, 42.9. Ratio return, 3 to 1. Motor, 30 H.P.. belted to oountenliilL
8 X 8 X 20 ft^ 3 toob. f X i in. cut; outtint epeed, 18 ft.; ^^...^
iron casting; H.r. for cut, 16; for return, 14-8; for reverae* 28.8.
return, 3 to 1. Motor, 25 H.P., belted to countershaft.
66 X 60 in. X 12 ft.; 2 tools \ X 1-16 in. out; cutting speed, 21 fl.; ph»-
ing 4 ton open hearth casting. H.P. required for cut, 10; lor retain, 14; ior
reverse, 16. Ratio return, 3i to 1. Motor mounted on planer iwi-MTf^ vUb
42-inoh 1,500-pound flywheel, running at 400 rein>luticmB. mounted on
motor shaft; flSrwheel used as driving pulley for return of plateo.
28 X 52 in. X 6 ft.; 1 cutting tool, f X i in. cut; cutting speed, 22 It;
planing 3-ton iron casting. H.P. required for cut, 3.1; for retiimi3.8; lor
reverse, 4.4. Ratio return. 4 to 1. Motor, 3 H.P., 800 revolittiona. Aver-
age load on motor, 2.48. Flywheel, 30 in. diameter, ^M pounds, €00 rev»*
lutions, mounted on motor shaft and used as puUey for return of pbten.
MlBCKLLANKOUS.
28 in. Qisholt turret lathe: machining Tropenas cast steel wei^t, 40O
pound; sise cut, one tool, | X 5-16 In.; 4 tools, | X 5-64 In.; weight casUac
400 pounds; power for cut, 3.9 H.P
21 in. drill press; power required, 1 H.P.
5 ft. radial drill; aGeiximum power required, 2.03 H.P. Motor used, 2 H.P.
600 revolutions.
Double and emery wheel stand ^ wo 18 X 2 in. wheels, 950 rev.; 2 laboren
grinding castinM; maximum H.P., momentarily, 6; average, 3.5. Motor,
6 H.P., mounted on grinder shaft.
10 ft. boring and turning mill; cutting tools, 2; cut, f X 1-16 in.; euttinc
speed, 20 ft^ machining 3j6*ton casting; H.P. required for eat, 8.6. Motor
used, 12 H.P.
Blotter: cut, | X 1-16 in.; speed of tool. 20 ft.; machining opeo hearth
steel castings; power requiried, 6.98 H.P.
Flat turret lathe; 1^ H.P. motor required.
Gisholt tool grinder; speed, 1,600 to 1.800 rev.; power required, 7 for
short periods, 4 on average. Motor used, 5 H.P.
The figures given in the following table for the power required to run
the planing machines empty, do not include the maximum horse-power at
the m stent of reversal, but represent the average forward and return of the
empty table.
POWER REQUIRED FOR MACHINE TOOLS. 1517
ReaoHs of tests at the Baldwin Locomotive Works, Philadelphia :
Siie.
Material
Cut.
1
•
2
2
2
1
1
1
2
2
2
2
2
2
2
2
Horse-Power.
Kfaidof
Machines.
1*
Total Cuttfaig.
Min.
Max.
Ave.
Wheel lathe
84 in.
84 in.
84 in.
78 in.
78 in.
36 in. X 12 in.
62 in. X 35 ft.
62 in.X35ft.
36 in. X 12 ft.
24 in. X 13 ft.
36 in. X 18 ft.
56 in. X 35 ft.
56 in. X 24 ft.
90 in.
42 in.
4 ft. 6 m.
5 ft. 6 in.
40 in. X 15 in.
19 in. str.
Cast iron
Cast iron
Cast iron
Cast iron
Cast iron
Wrought iron
Wrought iron
Wrought iron
Wrought iron
Steel
Wrought hon
Wrought ht>n
Wrought iron
Cast steel
Cast steel
Cast steel
Cast iron
Wrought iron
Wrought iron
2.9
4.2
5.3
4.3
5.5
4.4
20.6
23.0
U.3
7.9
5.8
6.2
4.7
7.1
6.7
21.6
26.0
13.8
6.1
Wheel lathe .
6.1
Wheel lathe .
Boring mill .
• • • •
1.5
5.8
4.5
Boring mill .
Blotter . . .
Planer . . .
Planer . . .
Planer . . .
Planer . . .
i'.s'
1.4
• • • •
2.7
1.95
3.2
4.6
4.56
1.43
0.96
2.1
1.6
1.8
l.J
• ■ ■ •
.1.5
11.4
5.8
3.0
4.3
4.3
9.9
6.0
2.1
1.1
2.4
2.4
2.2
1.8
6.5
5.3
21.1
24.5
12.5
8 0
Planer . . .
Planer . . .
Planer . . .
Wheel htthe
is .6
16.0
■ « • •
13.7
17.7
16.7
13.8
16.8
6.38
Radial drill .
2 1
Boring mill .
4,6
Boring mill .
Blotter . . .
Shaper . . .
4.2
■ • ■ •
4.8
4.8
• • • •
9.7
4.4
7.3
7.3
Results of tests* in ten different plants by C. H. Benjamint to determine
the proportion of power absorbed by the counters, belting, line shaft, etc.
Useful
Horse-
power.
Nature of Work.
Boiler shop . .
Bridge work . .
Heavy machinery
Heavy machinery
Average . . .
Light machinery
Small tools . .
Small tools . .
Sewing machines
Sewing machines
Screw machines .
Average . . .
Friction Horse-Power.
Per 100 ft.
of Shafting.
Per 100 lbs.
i9i
Per 100 SG
of Shaft]
per minu
Per
Bear-
ing.
Per
Coun-
ter.
4.77
.205
.04
.650
.538
3.28
.137
.04
.337
.606
5.70
.233
.038
.581
.665
8.55
.306
.06
.799
.600
6.57
.220
.044
.567
.602
2.75
.276
.034
.204
.165
8.00
.400
.09
.689
.127
2.49
.233
.03
.240
.121
4.36
.430
.05
.397
.269
5.08
.134
.034
.406
.172
6.33
.381
.06
.633
.291
4.83
.309
.048
.428
.189
Per
Belt.
.477
.521
.453
.475
.481
.095
.119
.113
.208
.154
.235
.154
«>
I
Per
Man.
.310
.164
.707
.627
.452
.790
.109
.881
.180
.181
.296
.406
.877
.142
.160
.342
.380
.099
.152
.227
.204
.093
.396
.195
For group driving determine average horserpower for each tool, add these
together and use a motor with a capacity of irom 40 to 70 per cent of the
total thus obtained. The sise of motor will depend upon tne way the ma-
ehines are worked — i.e., cutting speed, feed, material cut, and whether mod-
em air4>ardened tools are used; also to what extent machines are to operate
simultaneonaly. The larger the group the smaller the motor relative to
total power.
1518 POWER REQUIRED TO DRIVE MACHINERY, ETC.
Motor Power for MaclUmo TooU. Act«»l MmaitmUaMmm^
William R. Trigg Worka.
Hone-power of motors used at the Wm. R. Trigg Works. Riehraond, ^
(See article by Wm. Burlingham, in September, 1902. Machinery,)
Machine. "Jf
18 in. Cincinnati D. H. shaper 3
10 ft. Pond boring mill »
18 in. Newton slott^* 7^
No. 6 Baush radial drill 5
5 ft. radial drill 5
14 in. Newton slotter 5
36 in. X 12 ft. Woodward & Powell planer 15
56 in. X 56 in. X 12 ft. Gray planer 20
30 in. X 80 in. X 8 ft. Woodward & Powell planer .... 10
No. 5 Mitts &, Merrill keyseater 8
No. 1 Newton floor boring machine 7.5
38 in. X 44 ft. shaft lathe 7.5
Niles hor. boring machine 15
No. 4 duplex milling machine, Newton 10
7 ft. Belts boring xmll 15
10-in. Betts slotter 3
51-in. Baush boring miU 7.5
No. 1 Acme bolt cutter ■ 7.5
42 in. X 42 in. X 20 ft. planer 15
Dallett A Co. portable deck planer 5
62 in. X 30 ft. Putnam lathe 10
36 in. X 25 ft. Putnam lathe 7.5
Z2 ft. Bending rolls
Driving 35
lifting 10
12 in. straightening rolls 15
No. 3 double punch 10
Duplex planer 15
Double angle shear 10
No. 4 punch 10
No. 4 pimch 10
No. 2 punch 5
No. 3 nor. punch 7.5
No. 6 Sturtevant blower 13
]HoiiiillMil Shops*
Horse-power of motors used at the Hannibal shops of the St. Joseph aad
HannibalRy. ^Railroad GaaetU.)
Macrink Shop.
Jtochine. ^Sr^r
54 in. planer 15
42 in. planer 10
32 in. planer 7.5
Emery grinder
Grindstone
Double centering machine 8
00 in. driving wheel lathe 6
2 quartering ends of same 3
48 in. lathe 5
18 in. slotter .
22 in. shaft lathe 6
Car wheel borer 5
Car wheel press 10
HOTOB POWER FOR MACHINE TOOIiS.
1519
Machine.
Journal lathe
GrindBtone
32 ixk. lathe
18 in. 8hai>er
40 in. vertical drill
4-spixidle gang drill
Millicif; machine .
Grinding machine
32 in. lathe
Flat turret lathe
18 in. lathe
18 in. brass turret lathe
16 in. lathe
16 in. lathe
16 in. lathe
I>rill
Mo. 6 radial drill
Acme triple bolt cutter
2 in. double bolt cutter
No. 6 radial drill
No. 5 oscillating grinder
24 in. lathe .
24 in. lathe
Acme nut tapper
16 in. tool room lathe
No. 2 oflcillatins grinder
T'wist drill grinder
Boiler Shop.
No. 6 Nilee power bending rolls. . . .
Double punch and shears
Flue tumblers
Flue cutter
Flue scarfer
Small punch
Blacksmith Shop.
Bolt header
Grindstone
Bolt shears
Punch and shears
Bradlev hammer
Forge blower
Forge fan
Wood Mill.
Automatic cut-off saw
38 in. band resaw
Vertical borer
Automatic car gainer
Mortiser
BuBz planer
Single surfacer
Planer and matcher
Self-feed large rip saw
Small rip saw
Four-aided timber planer
Power feed railroad cutoff saw ....
Rip saw
Outside moulder
Double surfacer
Upright moulder
Large tenon«>»r
Soroil
Horse-Power
of Motor.
10
4
5
2
7.6
3
3
5
6
25
6
3
2
35
0
15
3.5
2
5
5
7.6
5
15
10
10
8
7
15
15
7.
13
25
25
15
45
10
15
22,
17.
5
5
9.5
7.5
2
1520 POWER REQUIRED TO DRIVE MACHINERY, ETC.
Machines. ^TfotoT*
Sharpener and gummer ,
Band saw, setter and filer !.!!*.'*
Emery wheels '..'.'
Grindstone !]!!!!!!!*' 5
Shavings exhauster *.*.'!! JSO
Elevator ! ! I I ! 7.5
Cabinet Shop.
Patternmaker's lathes k
Scroll saw !!!!!!!! 3
Tenonins machine !. "!!!!!!!! 5
Hollow onisel mortiser ...'...!!!][ 4
Universal saw bench !!!!!!!!! 5
Cemtml Railroad of Mew JToney Sk«p«.
f A^^JSSflPS^^'^ffa^ motors used at the Central Ry. of New Jcraey Sbofc
^™"^- of Motor.
88 in. wheel 7*
72 in. driving wheel 6
Single head axle 2
Double head axle S
36 in. X 16 ft 4
33 in. X 18 ft 3
30 in. X 12 ft 3
24 in. X 16 ft 3
42 in. X 14 ft 3
28 in. X 12 ft 2
Plansrs, Slotters, Shapeba.
60 in. X 60 in. X 25 ft. Pond planer 15
36 in. X 36 in. X 10 ft. Pond planer 5
36 in. X 36 in. X 10 ft.planer 7*
24 in. X 24 in. X 6 ft. Pond planer 6
48 in. X 54 in. X 14 ft. planer 7|
24 in. crank planer 4
16 in. traveling head shaper 3
8 in. Blotter 3
14 in. Blotter 4
24 in. Blotter 4
Boring and Turning Mills — Boring Machines.
80 in. boring mill • 5
39 in. boring mill 6
39 inch vertical boring machine 3
36 in. car wheel boring machine 5
8 ft. boring mill with Blotter 7J
Driving wheel quartering machine 6
Rod borer 3
Drill Presses.
No. 3 Bickford radial drill 3
30 in. drill press 2
30 in. drill press 2
40 in. drill press (floating) 3
40 in. drill press ., 3
40 in. drill press (floating) 3
8-spindle arch-bar drill 6
Grinders.
B. & S. surface grinder 3
Water tool grinofer 5
Angle cook grinder 8
^
MOTOR POWER FOR MACHINE TOOLS.
1521
M1BCB1.LANBOU8. Horae-Power
of Motor.
1 in. throat single end punch 10
«. 6 bulkloaer complete 7i
in. heading and forging machine 10
ewton colo-eaw 10
in. bolt heading machine 6
in. Acme single head bolt cutter 2
olt shears 4
> ft. boiler rolls 5
t in. driving wheel press 5
2 in. car wheel press 6
i in. car wheel press 3
Aa Ide»i llali«»iiy Shop.
EVitimated motor power for various tooLi for a railway shop. (From a
aper read before the Blaster Mechanics' Convention. June, 1002. by
». K. Pomeroy.) Horse-Powi*
> in. driving wheel 7.6
J in. driving wheel 7.5
2 in. truck wheel tire turning, heavy 5
jcle, single, heavy, for driving axles 5
.xle, double head 5
3 in. X 14 ft. engine, heavy 5
S in. X 16 ft. engine, heavy 3
[> in. X 12 ft. engine, heavy 3
3 in. X 12 ft. engine, heavy \ . . . 2
a in. X 8 ft. engine, very heavy 2.5
0 in. X 10 ft. engine, medium
3 in. X 10 ft. en^nne, medium
9 in. X 8 ft. engme, medium 2
X 24 flat turret 3
1 in. heavy screw machine 3
0 in. universal monitor, for brass 1
3 in. universal monitor, for brass 2
5 in. Fox lathe, with turret 2
2 in. speed lathe 2
Dbill Prbsseb.
2 in. radial, heavy 5
J in. radial, heavy 3
3 in. radial, medium 2
9 in. upright heavy 3
B In. upright heavy 2i
0 in. upright, heavy 2
0 in. upright, light 2
otter arilung machine 2
ensitive drilT .6
Grinding Machines.
Andls grinder for piston rods, etc 3
urface grinder 3
rniversai grinding machine (name as No. 2 B. & S.). . . . 2
wist drill i^der 2
ellers or Disholt tool ^nder 3
'wo 20 in. wet tool grinders 5
mall tool grinder (B. & S. No. 1) 1
lexible swinging, grinding, and polishing machine .... 3
Arge buflSng and polishing wheel 2i
Planers.
2 in. X 72 in. X 14 ft 16
0 in. X 60 in. X 28 ft 16
4 in. X 62 in. X 14 ft 16
2 in X 42 in. X 16 ft 10
8 in. X 38 in. X 10 ft 7.6
6 in. X 36 in. X 10 ft 7.6
0 in. X 30 in. X 8 ft 6
1522 POWER REQUIRED TO DRIVE MACHINERT, ETC-
Shafbwi. Hoi»-Po
ofMoCoc
16 in traveling head shaper 2
16 in. shaper 2
14 in. shaper 2
12 in. shaper 2
Richards side planer, 20 in. X 6 in 5
SLorriNG Machines.
18 in. slotting machine 7.5
14 in. slotting machine 5
10 in. slotting machine 3
Colbum keyseating machine 5
Boring MojiS.
84 in. boring and turning mill, two heads 7.5
62 in. boring and turning mill, two heads 5
37 in. boring and turning mill, two heads 5
30 in. horiaontal boring and drilling machine 5
CyUndn* boring machine 7.5
Milling Machines*
Heavy vertical milling machine 10
Vertical milling machme (No. 6 Becker-Brainard) .... 7.5
Heavy slab milling machine 15
Universal milling machine (heavy) 5*
Plain horixontarmilling machine (same as Becker-Brainard
No. 7} 4
Small, plam milling machine for brass work 2.5
Universal milling machine (same as B. A S. No. 3} . . . . 1
Bolt and Nut Machinsrt.
24 in. single head bolt cutter 2
It in. double head bolt cutter 4
5Hspindle nut-tapping machine 8
Bolt-pointing machine 8
Nut-tacing machine 3
Heavy power hacksaw 2
Small power hacksaw I
BLACKSMITHfi' ToOLS.
Quick-Acting belt hammer 6
3 in. bolt holding and upsetting machine 8
\k bolt heading and upsetting machine 3
Heavy shear to out 4 X 4 bar 7^
Shear to cut up to 5 X 1 in 5
Shear to cut up to 1\ in. round iron . ^ S
No. 3 Newton cold saw cutting-off machine 5
BOILRR TooxA.
] 6 ft. gap hyd. fixed riveter, pump, aooumulator, and orane,
complete 100
Heavy boiler plate punch or shear, 48 in. throat depth . . 10
Heavy boiler plate punch or shear, 30 in. throat depth . . 7.5
Tank plate punch, 30 in. throat depth 5
Tank plate shear, 24 in. throat depth &
Boiler plate shear, 30 in. throat depth, f in. plate . . 7.5
Flange punch 5
12 ft. boiler rolls for f In. plate
Light 6 ft. rolls 85
Plate planer, 20 ft 8
WOODWOBKINO TOOLB.
Patternmaker's lathe 5
Band saw 8
Medium-sized saw bench, crosscut and rip saw^ 6
Mediom-sised hand planing and jointing machine 6
HORSE-POWER IN MACHINE-SHOPS.
1523
•p*w«r la ]IIaclil«e-«lio|M; Vrfcttoi
(Flatber .)
M*ii Employed.
Name of Firm.
Ane A Bodley ....
r. A. Fay & Co
Jnion Iron Works . .
frontier Iron ABtbob W'ks
^ylor Mfg. Go
taldivin Loco. Works
W. Sellers & Co. (one de-
partment)
*ond Machine Tool Co. .
*ratt A Whitney Co. . .
Iiown A Sharpe Co. . .
f ale & Towne Co. . . .
Terracnte Machine Co. .
P. B. Wood's Sons . . .
Bridgeport Forge Co. .
linger Mfg. Co
ioweMfg.Co
W'orcester Mach. Screw Co.
Sartford " " •»
Nicholson File Co. . .
Averages
Horse-pow
er.
Men per Total
H. P.
6
Kind
of
Work.
ed to drive
Elf ting.
ed to drive
hinery.
ut to drive
ifting.
•
a
it
•
•s-^
F
quir
Mac
9x1
OS
.s
o o
g
&
&
9
^
o
2.27
o
7a
E. & W.W.
58
132
W. W.
100
15
86
15
300
3.00
3.53
£.,M. M.
400
95
305
23
160O
4.00
5.24
M. £., etc.
25
8
17
32
150
6.00
8.82
E.
«S
290
2.42
L.
2600
2000
600
80
4100
1.64
8.20
u. M.
102
41
61
40
300
2.93
4.87
M. T.
180
75
105
41
432
2.40
4.11
ti
120
725
6.04
It
230
900
3.91
C.&L.
136
67
68
49
700
5.11
10.25
P. AD.
36
11
24
31
90
2.57
3.75
P. & S,
12
30
2JM>
H. F.
150
75
75
50
130
.86
1.73
S. M.
1300
3600
2.69
II
360
1600
4.28
M. S.
40
80
2.00
fi
400
100
300
25
250
0.62
0.83
F.
360
400
1.14
2.96
346.4
38.6%
818.3
5.13
Abbreviations : E., engine ; W.W., wood-working machinery ; M. M.,
nlning machinery ; M. E., marine engines; L., locomotives; H. M., heavy
nachinery: M. T., machine-tools; C. &L., cranes and locks; P. & D..
iresses and dies ; P. & S., pulleys and shafting ; H. F., heavy forgings :
». M., sewmg-machines ; M. 8., machine-screws ; F., files. ^^
Teste »t tlie irm. R. Vrlsir fVorks.
(See September, 1902, Machinery.)
02 in. X 30 ft. lathe, turning hard cast iron. Tool of Sanderson self-
lardening steel. About 6 H.P. required to nm the lathe light. Experi-
nents: (1) Cut, \ in. deep, 1-16 in. feed; 21 ft. cutting speed; 33.8 lbs. metal
"emovea per hour; 1.16 H.P. = .034 lb. wt. metal removed per hour. (2)
iTnt, i in. deep, 1-16 in. feed: 33 ft. cutting speed; 54.8 lbs. metal removea
>er hour; 1.52 H.P. •-■ .028 Id. wt. metal removed per hour.
36 in. X 12 ft. Woodward & Powell planer, two tools cutting on cast steel.
)ut8 were \ in. deep by 1-16 in. feed. First experiment, cutting speed, 17.15
t. per minute; reverse speed, 60 ft. per minute. H.P. cutting, 2.15; retum-
ng, 2.22; reverse to cut, 4.77; reverse to return, 11. Secona experiment,
mtting speed, 21.83 ft. per minute; reverse speed, 68.6 ft. per minute. H.P.
ratting, 2.85; returning, 3.06; reverse to cut, 6.52; reverse to return, 11. In
>he0e experiments the reverse to cut consumed (of course for an instant only)
torn. 2.22 to 2 29 timee the power required to cut; and the reverse to return
r
1524 POWER REQUIRED TO DRIVE MACHINERY, ETC.
from 4.05 to 3.59 the |x>wer required to return; or from 5.11 to3JB6 tki
power required for cuttiuK.
36 in. X 25 ft. Putnam lathe, cutting shaft nickel steel, oil tempered^
annealed, with Sanderacm self-hardening tool steel. Diameter work, 9) k.
Experiments: (1) Cut i in. deep X i in. feed, 5.76 revolutions. H.P. - li.
(2) Cut 3-16 X I. 4.65 revolutions, H.P. - 1.76. (3) Cut ^ X i. 3^
lutions, H.P. - 1.9. (4) Cut i X i, 2.71 revolutions, H.P. - 1.26.
Another line of experiments was conducted with the same lathe c
nickel steel shaft 9} in. diameter, cut constant at i in. deep and feed i k-pv
revolution. The speed of motor was gradually increaeea from No. 3 Km.
to No. 11 notch of the controller, representing an increase of motor rends-
tione from 220 to 700 per minute, or an increase in the revohitioos of tte
lathe from 3.03 per minute to 9.64 per minute. The H.P. required mc
from 1.068 to 4.26.
Cotton Machimoiy.
Wii. O. Webber.
Loom.
Make.
Amoskeag, Whitin
Amoskeu, Whitin
Lowell Snop . . .
Lowell Shop . . .
Lowell Shop . . .
Whitin
Amoskeag ....
Whitin
Width.
Picks
per Min.
49 in.
45 in.
40 in.
36 in.
32 in.
40 in.
48 in.
40 in.
142 ft.
142 ft.
160 ft.
160 ft.
170 ft.
144 ft.
144 ft.
147 ft.
Picks
per Inch.
68X80
68X80
72X80
64X90
64X88
80X84
80X84
84X92
Warn.
we«r
Huni
24 X31
.354
24 X31
.214
24 X31
.S3
24 X38
.»
27iX3S
.311
28 xa3
.SIU
28 X33
.X7
28 X33
.SSI
Slashers. — 2,872 ends
Cut in 84 seconds »■ 3.93 horse-power.
Cut in 64 seconds ■> 4.574 horse-power.
Cut in 52 seconds » 5.53 horse-power.
Warpers. — 359 ends, 50 yds. per min. — .313 H.P.
Shears, 4 blades and fans, 1,800 R.P.M.
100 yards per min. 42 inch cloth <
Cards.
6.07 H.P.
Finisher, Lowell ...
Finisher, Amoskeag .
Finisher, Whitin . .
Lowell breaker ...
Amoskeag breaker . .
Whitin breaker . . .
Revolving top flat card
Hone-
poww.
36 inch cylinder
128 R.
.187
36 inch cylinder
140 R.
.2*7
36 inch cylinder
140 R.
.10
36 inch cylinder
128 R.
.225
36 inch cylinder
140 R.
.247
36 inch cylinder
140 R.
.173
40 inch cylinder
163 R.
.921
POWER REQUIRED.
1525
Wif. O. WXBBKB.
o
a
13
27
in. X 62 in. 2 rev. No. 8 Cottrell press^ 19 impreaflions per minute
in. X 41 in. No. 20 Adams press, 16 impressions per minute
~n. X 64 in. Huber perfecting press
n. X 64 in. Huber perfeotinff press, autopiatio feed
n. X 41 in. No. 4 Adams job press
12
n. X 40 in. No. 2 Adams job prei
n. X 54 in. No. 1 Potter cylinder roller press
n. No. 1 Hoe perfecting press
Web paper-wetting machine. . .
Horse-
Power.
1.189
.68
2.44
5.55
.43
.337
.50
5.41
.52
Newspaper PaiNTiNa Machinbrt.
One 10
One 10
One 12
One 12
One 32
page web perfecting press, 12,000
page web perfecting press, 24,000
page web perfecting press, 12,000
page web perfecting press, 24,000
page web perfecting press, 12000
per hour
per hour
per hour
per hour
per hour
Horse-
power.
15.39
31.
20.45
29.56
28.73
Cauco Printing Machinery — Capacity 100 yds. print goods per min.
One 19 cylinder, soaper and dryer, full ....
One cutting machine, full
One set drying cans to cutting machine, full . .
One back starcher, 3 wide machines, full ....
One indigo skying machine. 5 vats, all working full
One 40 in. 5 roll calender, working full ....
One single color printing machine
Rev.
Foot-
per
min.
pounds.
110
2,182
65
1.525
110
1.282
115
2.330
64
2.635
234
5,390
• ■ •
Horse-
power.
3.97
2.77
2.83
4.24
4.78
9.80
10.6
]Pow«r Required For Aewiafp^nfiichlBea*
Light-running 20 machines to 1 h.p.
Heavy work on same 15 " " "
Leather-sewing 12 ** " "
Button-hole machines ... 8 to 12
1526 POWER REQUIRED TO DRIVE MACHINEBY, ETC.
POW^KR COMAHniPVMOBr.
Character
of Installations.
Bakeries .
Bakeries
Boiler shops
Boiler shops
Boots and shoes . . .
Box making
Blacksmiths
Brass finishing ....
Butchers and packers .
Butchors and packers .
Breweries .^
Carpet cleamng . . .
Cement mixing ....
Candy manufactory . .
Candy manufactory . .
Cotton mills
Carriage works ....
Chemical works . . .
Clothing manufacturing
Grain elevators ....
Feather cleaners . . .
General manufacturing
Engrv. and electrotjrpmg
£2ngrv. and electrotjrping
Glfws grinding . .
Founoriee ....
Foundries ....
Furniture manufacturing
Flour mills
Hoisting and conveying
Hoisting and conveying
Ice cream
Refrigeration ....
Jewelry muiufacturing
Laundries ......
Marble finishing . . .
Machine shops ....
Newspapers
Newspai>ers
Ornamental iron works
Faint manufacturing
Printers and bookbinders
Printers and bookbinders
Plumbing manufacturing
Rubber manufacturing
Sheet metal mfg. . .
Soan manufacturing
Seeds
Structural steel . .
Structural steel . .
Stune cutting . .
Tanners
Tobacco working .
Wholesale groceries
Wood working . .
Woolen mills . . .
Averages ,
Average
K.w:
Hours
per
Month.
1,582
705.
326.
1,172
3,050
1,555
586
6,736
1.990
1,049
12,310
644
2,009
1.893
796
11.829
2.091
4.802
1,181
3.842
2,447
6,133
863
2,369
2,760
2,067
2,419
1.750
41,276
2.905
6.562
596
4.645
2,526
676
1.464
4,006
3,150
4,975
2.771
2.814
1.147
6,215
3,020
1.051
1,321
3,434
2.917
6,514
77,704
7,425
2,466
3.441
2.005
2 306
20.985
Average
Con-
nected
Motor
Load,
H.P.
32
22
51
32
39
18
9
40
24
36
94
14
37
26
29
99
24
109
23
114
54
67
12
46
33
27
81
35
148
70
253
31
36
31
10
19
57
47
137
38
60
20
76
42
26
38
73
55
176
552
76
28
62
47
89
150
.8
.5
.4
.2
.7
.1
.4
.6
.8
.9
.0
.5
.6
.6
.9
.0
.8
.4
.4
.5
.4
.3
.5
.7
.1
.7
.5
.6
.7
.7
.8
.8
.6
.4
.0
.4
.4
.4
.8
.4
.0
.8
.0
.1
.0
.1
.5
.6
.3
.0
.5
3,500 I
Indi-
vidual
or
Group
Drive,*
I
G
G
G
G
G
I
G
G
G
G
I
G
G
G
G
G A
G A
G
I
G
G
h
G
G
G&I
G&I
G
G
G&I
G
G
I
G
G
I
G
G&I
G
G
G AI
I
G
GftI
G
G
G&I
GftI
G
Ave.
No.ofi
Mo-
tors.
2.7
3.1
2.8
5.2
6.8
4.3
2.2
7.4
2.0
6.7
4.6
1.6
1.0
3.5
7.5
3
3
5
4
3
0
5
5
0
8
.5
.7
.0
.3
.0
2
26
3
2
7
3 6
3 1
6.4
20.0
5.4
2.5
4.6
2.1
1.3
4.5
4.8
17.3
3.6
4.6
2.6
24.0
4.8
15.
3.7
10.0
5.8
16.1
35.6
3.8
2.6
7.0
4.5
3.6
3.0
GoDXMect-' = e
edMotcvlii
i »
• n
s
Av
Load
5.5
6.4
6.08
1
.9
.6
.3
1
.5
.5
.5
27.8
19.5
33.3
20.7
42.8
45.4
34.2
45.0
36.4
18.8
33.0
30
24.
33
16
60.
35
23.
44.
32.6
25.7
33.9
46.9
^.5
36.6
43.7
21.3
35.6
48.1
28.3
13.0
35.9
53.4
31.6
34.0
51.3
M.5
38.0
15.1
41.6
26.5
38.5
26.0
21.5
24.7
27.3
27.6
24.4
18.5
31.1
84.4
54.6
37.5
26.0
33.3
71.0
I
33.9
* G. stands for Group. I. for Individual.
IS
9
13
8
12
4
10
s
a
€
sa
»
2
la
S
7
«
15
IS
9
13
5
i
17
5
19
12
51
»
21
9
II
5t
»
15
17
3
5
6
«
5
4
17
64
POWER FOR ELECTRIC CRANES. 1527
Power for Sloctric Cnu
Journal Society of Western Engineera,
The following data on the power required for electric traveling was eiven
y Mr. S. S. Wales at a meeting of the Engineers' Society of Western Penn-
An electric crane is divided into three general parts — bridge, trolley, and
oist, each of which has its own motor and controlling system, ana each
al>jeeted to different conditions of work.
I* or the bridge, where the ratio of axle bearings to diameter of wheel is
letween one to five and one to sijc, the following table will answer our pur-
lose for weights and traction for different spans:
L « working load of crane in
tons.
W — weight of bridge alone in
tons.
10 <* weight of trolley alone in
tons.
S « speed in
I feet per mmute.
P "> poimds
per ton required.
Span.
W.
P.
25 ft.
.3L
30 lbs.
60 ft.
.6L
35 lbs.
75 ft.
1. L
40 lbs.
100 ft.
1.5L
45 lbs.
For the trolley we would assume the weight and traction as shown in the
following table:
L. W. P.
1 to 25 tons. .3L 30 lbs.
25 to 75 tons. AL 35 lbs.
75 to 150 tons. .5L 40 lbs.
Now the power required for bridge will be:
iL+W-\-w)xP XS
- H.P.
33.000
which result will be used in connection with the motor characteristic to
determine the gear reduction from motor to track wheel. As the nominal
H.P. rating of a series motor is based on an hour's run with a rise of 75° C.
above the surrounding air and as conditions of bad track, bad bearings, or
poor alignment of track wheels may be met with, H times the above result
should be taken as the proper sise motor for the bridge.
For the trolley the power required would be:
{L-\-w)XP XS „p
33,000 " "•*^"
which will be used for speed and gear reductions, but l\ times this should
be used for size of motor.
For hoist work we cannot have so large margin of power, as the variation
from full load to no load may imply a possible dangerous increase of speed,
and unless the crane is to be subjected to its maximum load continuously or
is to be worked where the temperature of the surrounding air will be high,
it is safe to use the sise found by assuming 1 H.P. per 10 it. ton per minute
of hoisting. This is nearly equal to assuming the useful work done as 60
per cent of the power consumed.
As an illustration, let us take a crane of 50-ton capacity, lifting speed of
hoist 15 feet per minute. Bridge to be 70 feet span and to run 200 leet per
minute with load. Trolley to travel 100 feet per minute with full load.
On the foregoing assumption the bridge would weigh 50 tons and require
40 pounds per ton for traction, and the trolley would weigh 20 tons, and
require 35 pounds per ton for traction.
The power for the bridge would be:
120X40X200 ^ „p
33.000 ^ "•*^-
r
1528 POWER REQUIRED TO DRIVE MACHINERY, ETTC.
and the sise motor li times thia would give 43^ H.P. or 50 H.P^ tKi
beinc the nearest standard sise, and the specification should read not k*
than 50 H.P. motor to be used for bridge travel.
Similarly the trolley will require
70 X 85 X 100 - . « T, p
33,000 /.««.*-.
and the siie motor required will be 1^ times this, or 8 . 28 H.P.
The hoist would require
50X 15
10
- 75 H.P.
and would be specified not lees than 75 H.P. motor to be used as hoists.
attag* C«at of Electric KleTatoi
From Cvreular of CijteinnaU Oat and Eleetrie Co.
Six Months' Average.
Freight Elevators.*
*
Passoiger Elevators, f
No.
H.P.
Avenge
Monthly
Cost.
1
No.
H.P.
Averaee
Monthl;
Cosi.
*
10
$11.02
1
•
15
$39.54
10
10.00
2
20^
19.05
5
20
33.01
1
18
65 83
5
5.00
2
m
22i
17.30
5
4.00
1
23.57
5
5.00
1
15
14.22
5
4.00
5
73
59.40
5
7.37
2
32
3S.16
5
4.00
3
3Sh
lol
34.55
5
11.86
2
19 .»
10
0.50
1
8
9.73
1
10
0.50
1
8
14.87
1
. 8i
9.49
1
11
18.42
2
"25
23.75
1
15
9.15
5
3.50
1
15
22.01
10
9.50
1
15
4.75
\
5
4.75
2
164
17.62
10
11.30
1
12
14.66
8
7.60
2
12
12.33
20
28.06
2
11
17.74
7i
7.12
3
41
37.95
5
4.75
1
10
23.49
5
4.60
1
16
18.21
5
5.25
1
10
19.05
7i
7.12
1
10
19.50
1
1
13
10
13.30
18.96
30
221 k
$241 .95
1
45
26
523
35.31
9658.58
* Average cost per elevator per month $8. Average cost per mootb
per horse-power, $i .09.
t Average cost per elevator per month, $14.64. Average oost permoi^
per horse-power, $1*26.
POWER USED BY MACHINE TOOLS.
■dTlBC ^ Slectrlc Drive. — Fie- No*. 3 uid 3 abow (mpblaklly
« ssvins miule ia power by the use cd elwr-- -"- — *'— '
ttftinc And bflltiog.
■ diiva over th* uh a
I89S, Diunm of U
Factory ol Central Sta
Flo. 3. 1805, Diasrmm of Lomh in
_ _ _ Power Truiimi»ian.
Factory ol Central Blampinc Co., Nevsrlc, N.J.
Ctocker-Wlwlsr Electric Companr.
I
1530 POWER REQUIRED TO DRIVE MACHINERY, ETC-
lilftT OJF TOOUi AiriB
DYMAMOA.
1 Tool chest.
1 Magneto and cable.
1 Speed indicator.
1 Tape line, 75 ft.
1 Rule, 2 ft.
1 Scraper, for bearinge.
1 Blow lamp.
1 Clawhammer, No. 13.
1 Ball pein hammer, No. 24.
1 B. A S. pocket wrench, No. 4.
1 Monkey wrench, 10 inch.
1 Set (2) Champion screw-drlTers.
1 Large screw-drlTer, 12-lnch.
1 OfT-eet Bcrew-driver.
1 Ratchet brace. No. 33.
Bite, i, I, i, 1, 1. 1, 1 inch. ^
1 Clarke BxpanBive bit, | to 3 Inch.
1 Screw-drirer bit.
1 Gimlet bit.
1 Wood countersink.
1 Extension drill, f in. length, 24 in.
1 Long or extension gimlet.
1 Cold chisel, (inch.
1 Half round cold chisel.
1 Gape chisel.
1 Wood chisel, firmer paring, I inch.
1 Brick drill.
Files, one each : round, flat, half-
round and three^qusov.
1 Saw. 20 inch.
1 Hack-eaw, 10 ineh.
10 Extra saw blades.
1 Plumb bob.
1 Brad awl.
1 Pair oarbon tongs.
1 Soldering oopiMr, No. 3.
1 Pound of solder.
1 Pair of climbers.
1 Com*4ilong.
1 Splieing-cliunp.
1 Strap and rise.
1 Pair line pliers, 8 inch.
1 Pair of side-cutting pliers, 5 iaek
1 Pair of diagonal-cutting pliers.Sta
1 Pair of round-nose pllera,5iBek
1 Pair of flat-nose plien, 5 in^
1 Pair of burner puers, 7 Ineh.
6 Sheets of emery clotA.
6 Sheets of crocus cloth.
2 Gross of assorted machine
2 Gross of assorted wood ;
150 Special screws.
Taps, 6-80, 10-24, 12-M, 18-18.
Drills, 34, SI, 9, 16-64.
Tap wrench.
The following-named tools will probably be required in eonatnietiag &•>■
for city or oommerclal lighting ;
(Davis.)
Article.
Stubs* pliers, plain ....
Climbers and straps ....
Pulley-block and ecc. clamp
Come-along and strap . . .
Splidng-clamps
Linemen's tool-bag and strap
Soldering-furnoce ....
Gasoline blow-pipes ....
Soldering coppers
Pole-hole shorels
Pole-hole spoon, regular . .
Octagon digging-bars . • .
Tamplng-bars
Crowbar
Pick-axe
Carrying-hook, heavy . . .
Cant-hook
Pike-poles
Pole-supporter
Comb, pay-out reel and straps
Nail-hammer
Linemen's broad hatchets .
Drawing-knives
Hand-saw
Ratchet-brace, bits ....
Screw-drivens
Wrench
Mflle
Sise.
Sin.
To
No. S
B.&8.
21b.
8 ft.
7ft.
8 ft.
7 ft.
101b.
4 ft,
16 ft.
6ft.
' i lb!
6 in.
12 in.
96 in.
10 in.
8 in.
12 in.
12 in.
Cost
abouk
•2J0
3J0S
8jOO
2J5
SJS
4J0
6.60
$M
X
1.50
1.25
S.SO
^m
M
.75
6.0D
2J0O
2.40
12iM»
20jOO
UOO
IJO
2.10
IJO
3M
M
12
JO
^
THAWING WATER PIPES.
1531
aBQniBKD IN UrSTALLINO 15 CITT liAMPB AKO 20 COMMBBCIA.L LA.MPB
OK A FIYB-XIUC OIBOUIT, SETTING POLBfl 183 FBBT APABT.
(Dftvis.)
Articles.
Leotrto-llght poles .
Lectrlc-Iight poles
lecirio-llgbt poles .
roos arms, 4-pin . .
KiAted oak pms . .
ftlc pins and bolts .
■oil break-arms . .
agK-florewB and washers
laea Inanlators, D. G.
ole steps ....
ay atranded cable .
romi arm brace and bolts
Ine wire .•••..
Size or
Diameter.
80 ft., 6 in.
36 ft., 7 in.
40 ft., 7 in.
4 ft.
inn.
l}in.
4x71n.
....
ftXSin.
I in.
GBS" '
Price
about
$2.40 each
4.15
5.50
.30
.02
.75
.04
jmi
M
.07 lb.
.20 each
126.00 mi.
Quantity.
180
• • •
40
200
800
24
25
400 -
860
2600
600 lbs.
40
6 miles
[jLvrnmaAJL wtm^k^MMMn for co]virECXKiff« nr
(DaTis.)
Ileet-proof pulleys . . .
,
$0.75 each.
30
Itreet-lamp cleats, iron
.25 "
16
Lro-lamp cordage . . . .
luspenaion cable ....
In.
1.26 hd. ft.
26
In.
.02^ ft.
1.501b.
3000 ft.
iu-d-rnbber tube ....
Xfin.
5 lbs.
loft-rnbber tubing . . .
In.
.20 ft.
200 ft.
Lro cnt-out ......
3.60 each
20
^o^oelBln insulators and
screws
• • * • *
2.40 hd.
400
>ak brackets and spikes .
2.60 "
160
VKA^TMirC} FliOZBlV -WJkTKWk PIPES
B]:.BGTlftKCAI<I.Y.
The use of electricity for thawing out frosen underground water pipes
uires a transformer say of 10 or 20 kilowatts capacity, which can be
mn to the locality required, connecting the primary with the hish ten-
non circuit passing the place, and then connecting the secondary tnrough
in ampere meter and rheostat to the service in trouble. Where services
from tne street mains to two adjacent houses are both frosen, it is only
aeeeoBory to connect the secondly circuit to the kitchen faucet of both
boiieee ud thus the circuit is complete through the service of one house
bo the street main and back through the service of the second house.
Where the service of but one house is to be thawed, one end of the sec-
ondary circuit is connected to the kitchen faucet and the other end to the
nearest street hydrant or other street connection. Currents varyiiu[ from
90 to 500 amperes are used, obviously, varying according to the conditions;
ftnd the time taken to thaw the ice sufficiently to start the water running
will be from 10 to 45 minutes or perhaps 3 to 8 hours, according to circum-
1532 POWER REQUIRED TO THAW WATER PIPES.
enaed m
aobdtd
The averace time for the ordinarv house aerrioe will
minutes, whue for a five or six inch pipe thai has been froxen at^
highest amount of current and time mentioned will be reqm
^It is very seldom necessary to melt the entire plug of ice, mm ifae ttawisf
of a thin sheet nearest the metal will start the water nmning and th*! i3
consume the ice in a short time.
The following table is compiled from data that have appeared in ymm
periodicals. It represents average conditions for last year, and sbovi vkl
may be expected in the future:
Sixe
Pipe.
Length.
Volts.
Amps.
Time Requited
to Thaw.
J
40 ft.
50
300
8 nmu
100 ft.
55
135
10 miiu
m
250 ft.
50
400
SOmin.
0
250 ft.
50
500
20 min.
1'
700 ft.
55
176
5 hnc
V
1300 ft.
55
260
3hr«.
10'
800 ft.
70
400
2hr8.
The following notes on melting points of various substances may be of
assistance ia checking thermot^eters and showing the ^e limits on ckfr
trica! apparatus that operates m heated conditions.
CL F.
Pure cane sugar (granuWed) melts at 160 39
Tin melts at 235 «5
Bismuth melts at 260 51$
Lead melts at , 327 US
Zinc melts at 419 7SI
«
INDEX.
1b1»«"«Tt»tl«iMi for units, 6.
aaohxo, value of, 7.
boolute unita, 2.
tMort>ent for X-ray tubes, 1251.
bvolt, value of, 7.
Boeleration, average rate of, 660.
definition of, 3.
formula for, 664.
oetic acid in electrobrte, test for,
878.
cheson process, graphite produc-
tion by, 1245.
«dd, conducting power of, table of,
905.
.eker process, caustic soda by, 1240.
teoustio telephone call system, 294.
LCtion of wattmeters, 1039.
kctive materia], increase of, 873.
Io08 of battery plates, 881.
Leyclio machines, def . of, 504.
kdhesion of cement, 1294.
kdmittomoe, symbol of, 8/
Admixture of copper, effect of, 144.
Id vanoe wire, properties of, 202, 207.
kerial circuits, charging current per
1000 feet of A.C., 25^-258.
lines, res. of, 61.
telephone cables, 188.
capacity of, 1085.
wires, capacity per 1000 feet of,
table of. 252.
location of crosses in, 327.
igeing of iron and steel, 455.
of transformers, guarantee agai^t
serious, 498.
tests, curves of, 453.
K. I. E. £., copper wire tables of,
146.
yr-blast transfonners, 449.
dielectric strength of, 233.
-gap ampere turns, 367.
break down, 1056.
Air-gap, discussion of. 363.
flux. 365.
pumps, 1445.
resistance, effect of moving body
on, 650.
space in grates, 1329.
spec. ind. cap. of, 35.
Alarm, fire, U. S. Navy, 1210.
Alcohol, spec. ind. cap. of, 37.
All-day efficiency of transfonners,
454.
Alloys of copper conductivity of,
table of, 910.
of copper, table of, 144.
phys. and elec. prop, of, table of,
134-140.
Alternating circuits, power in, meas.
of. 69.
current ammeters, use of. 945.
arc circuits, reactance coil for.
466.
arc lamps. 568.
armatures, 410.
circuit breakers, design of, 952.
circuits, protection against
abnormal potentials on, 981 .
circuits, prop, of, 259.
definition of, 502.
distribution, pressure for. 261.
electrolysis, 860.
electromagnets, 127.
flow, formula for. 1216.
lines, table for calc, 279.
mess, of, 26, 42.
motor equipments, weight of.
719.
motors, 421.
potential regulators. 467.
power curves. 70.
railway motor characteristic,
713.
system, 707.
1633
r
1534
INDEX.
Alternating current railway trolleys.
640.
meaa. self-induotion with, 06.
sini^e-phaae aub-etation, views
of. 943.
switchboard panda, 912.
voltage and current in terms of
D.C.. 438.
wiring examples, 272.
Alternators, parallel running of, 419.
regulation tests of, 382.
regulators for. 409.
revolving field type, 409.
armature reaction of. 414.
connected in multiple, 420.
definition of. 502.
E.M.F. of. 404.
Aluminum and copper compared ,
195.
alloys, spec, gravity of, 1514.
bar daU, 911.
conductors, calo. of, 277.
fusing effect of current on, 217.
phys. and elec. prop, of, 134.
production of, 1238.
spec. res. of, 132.
temperature coef. of, 133.
wire, cost of. 195. '
deflection in feet of. 226.
for hi^ tension lines, 199.
limit df sag for, 225.
properties oC, 194.
reactance factors for, 266.
sldn effect factor for, 238.
stranded, dimensions of, 197.
table of resistance of, 196, 198.
weather-proof, 197.
Alundum furnace, 1245.
Amalgamating sine, 14.
Am. Inat. of Elec. Bng., rules of, 501.
copper wire tables of, 146.
Ammeters, A. C. type, use of. 945.
and voltmeters, meas. res. with, 78.
Bristol recording, 1036.
description of, 41.
diffei«ntial, use of, 903.
jacks for, 922.
scales of, figuring of, 946.
shunts for, 41.
■oft iron, 41.
Ammunition hoist, dectric, ll4
1191. I
Ampere, definition of. S. j
-hour meter, Shallenbager, IQO^
International, def . of, 9.
measurement of, 10.
specification for detenninmc. ^
value of, 8.
Hums for armature toaUi. 367. I
in field magnets, 366. i
of A.C. annatores, 414. I
of aip*sap, 369.
of electromagnets, table of. lU
of plunger solennide, tabic 4
128.
Analyses of boiler feed watets, 1311
of coals. 1352.
of coke, 1353.
of gaseous fuels, 1357.
Anchorage of trolley wires, 637.
Anchored lamps, navy spee. N
1173.
Angle of lag in thrae-plmee eimsa
406.
Angular dist&noe betweeu braahe
table of, 344.
velocity, 3, 1505.
Anilln, spec. ind. e^». of, 37.
Animal oils, 1497.
Annealing of armor plate, eleetiu
1274.
Annual expenses of telephone eafaia
1087.
Annunciator wiring. 294.
Anode, definition of, 1229.
impurities, effeet of, 1237.
Answering jaoks, 1091.
Antenna, 1057.
Anthony bridge, diagram of, 31.
Anthracite, properties of, 1351.
sising tests of. 1354.
Anti-cathode, use of, 1248.
Anti-coherers, 1066.
Antimony, phys. and dee. prop. ^
134.
spec. res. of, 132.
temperature oocf.^. 133.
Ansdeoe, spee. ind. eap. of, 37.
Apothecaries' measure. 1500.
Apparent power, def. of, 505.
^
INDEX.
1535
■dud oil, spec. ind. cap. of, 37.
e, chemical effect of eleetrio,
1232.
sireuita. reactance coil for A. C,
466.
dsnuuno, efficiency curves of, 338.
axt. ohamoteristie eurve of, 337.
permeability curve of, 388.
lamps, candle-power of, 570.
claaaiiication of, 668.
regulation in, 576.
trimming of, 583.
U^t carbons, tests of, 577.
circuits, ins. res. of, 81.
efficiency, 580.
installations, table of, 508.
rectifiers, G.£. mercury type, 480.
station iii^tning arrester, 086.
switchboards, 022.
type furnace, 1244.
bdois signal system, 1181.
Umature coils, allowable number of
turns for, 374.
eoils, placing of, 358.
trial slots for, 373.
values for number of, 373.
wire for, 372.
conductors, carrying cap. of, 375.
drag on, 351.
sise of, data on, 358.
commutation, 364.
cores, data on, 357.
disks for. 356.
energy dissipation in, 107.
hysteresis in, 341.
niagnetic density of, 357.
faults, tests for, 402.
ground, test for, 402.
losses, formula for, 358.
reaction, 350.
data on, 364.
in alternators, 414.
rsBistanoe loss, meas. of, 500.
mees. of, 70, 401.
shafts, 341.
slots, design of, 357.
sises of, 372.
teeth, ampere turns for, 367.
teeth, design of, 857.
winding, 342.
Armature colls, constants, 376.
for converters, 441.
Armatures, disk type, 341.
drum type, 341.
heating of, 340.
of alternators, 408.
copper loss in, 407.
winding of, 410.
ring type, 341.
slotted or toothed type, 341.
temperature rise in, 358.
ventilation of, 350.
Armored submarine cables, 180.
Armor plate, annealing of, electric,
1274.
Army, U. S., use of elec. in, 1123.
Artificial light needed in each
month, 606.
Ash in American coals, 1350.
A.S.M.E. boiler test rules, 1384.
direct connected sets, standards
of, 1435.
Astatic galvanometer, Kelvin type,
23.
needle system, 23.
Atkinson repeater, 1048.
Atmospheric discharges, 1278.
electricity, effect on tran.<iformers
of, 440.
Auto-cohereiB, 1066.
Automatic block signallfng, 622.
booster, use of, 802.
exchange systems, 1105.
telephone ssrstem, 1122.
Automobile batteries, 1227.
electrolyte for, 877.
electric, 1224.
motors, 1227.
power required by, 1224.
Auto-starter, connections of, 054.
-transformer, def. of, 503.
railway control, 767.
use of, 420.
Auxiliary armature coils, 351.
bus bare, 035.
control ssrstem, 767.
D.C. circuits. 030.
power, 867.
relays, 056.
trunk signals, 1006.
r
1534
INDEX.
Alternating current railway troUeys,
640.
meafl. self-induction with, 66.
sincl^pbaae sub-etation, views
of, 943.
switchboard panels, 912.
voltage and currMit in terms ci
D.C., 438.
wiring examples, 272.
Alternators, parallel running of, ^
regulation tests of, 382.
regulators for, 409.
revolving field type, 409. ,
armature reaction of, 41>'
eonneoted in multiple, <
definition of, 502. ^es,
E.M.F. of, 404.
Aluminum and oop* .<e system
196.
alloys, spec, grs
bar data, 911. magn. values by,
conductors, r
fusing effec' ^ase circuit, energy
phsrs. and
product! j^jijrstem, 73.
spec, rr y^uita by transposition,
tempr
wirp J^cirouits in dynamos, 349.
' ^^flcc for arc lamps, 581.
'^rmers for three- wire seoond-
>. 472.
^ Locomotive Works, power
*^t^ts at, 1517.
^^^c galvanometer. 25.
^othod, determ. magn. values by,
91.
5. A. Ohm, value of, 131.
ggx9 wires, carrying capacity of,
208.
Barie, value of, 7.
Bam test for motor efficiency, 803.
Barometric correction, 519.
Barrel armature winding constants,
376.
Bars, commutator, number of, 361.
Baths for plating, 1233.
Batteries, automobile storage, 1227 .
dry, descr. of, 18.
E.M.F. of. meas. of, 62. 74.
E.M.F., comparison of, 76.
Ammniaf
*7.
»iw ^
f
,. ..reetifiera,&
' * "' .ver t3rpe. 16,
V, insta/lation of. «
, appearance of. S74.
ackling of, 881.
cadmium test d, S7S.
dimensions of, 883.
types of, 874.
system, three-wire, 91&.
transnutters, 1071.
troubles, 881.
while working, res. of, 61 .
Battle order indicators, U. S- K«^
1202.
service, navy, 115S.
Beams and channels, Trwttja, ■■
loads on, 1313.
spacing of, 1315.
bending moment of. ISOI
breaking load on, 13(9-
coefficient changes for ^toA
forms of, 1311.
coefficients for special caseK^.Ul^
deck, 1314.
deflection of, 1309.
flexure of, 1308.
general formulae for. 1309-
max. moment of stnas of, 1^^
modulus of rupture of, 190&
of uniform cross scetioo. tnas.
str. on, 1309.
of uniform strength. 1312-
resisting moment of, 130S-
safe load on steel. 1310.
on southern pine, 1^
on wood, 1318.
spacing of, for various loadi. I^^^
strength of white pioe, 1319.
transverse strength of, 1908-
Bearing friction in dynaiDoe, 3K-
friction, meas. of. fi08.
Bearings, meter, 1008.
Bell telephone reodver, 1070-
wiring, 293.
INDEX.
1537
^4>
t88.
ams. 1308.
4008 of. 1431.
a. cap. of, 37, 227.
^m of welding, 1274.
el, phys. and eleo. prop.
o.
oells, use of. 1103.
^r dynamos, armature wind-
ings for. 345.
JinninKham wire gauge. 141.
Bismuth, phys. and elec. prop, of,
135.
spec. res. of, 132.
temperature ooef. of, 133.
Bituminous coal, properties of, 1351.
Blacksmith shop machinery, power
to run, 1619.
toob. power required for, 1522.
Blake transmitters, 1072.
Bleaching process, 1244.
Bkwk signalling, automatic. 622.
system, distributed signal, 627.
Btondel oscillograph, des. of, 60-64
Blowers, e£Fect of temperature of
air on load of, 1346.
for forced draught, 1344.
Board of Trade, boiler rules of, 1332.
regulations, 781.
Boat cranes, navy spec, for, 1194.
Bodies of cars, weight of, 784.
Body of car, preparation of, 746.
Boiler feed water. 1362.
purification by boiling of. 1365.
flues, collapsing pressure of. 1429.
head stays. 1333.
plate, ductility of. 1333.
Boiler rules, U. S. statutes, 1832.
settings, 1334.
dimensions of, 1336.
shell, strength of riveted. 1330.
^8hop machinery, power to run,
1519.
strength of riveted shells of,
1330.
test codes, 1384-1392.
teste, A.S.M.E. code, 1384.
tools, power required for,
1522.
tubes, charcoal iron, siies of,
1428.
collapsing pressure of, 1429
Boilers, steam, 1327.
heating surface of, 1328.
horse-power of, 1327.
points in selecting, 1327.
safe working pressure for, 1330.
types of, 1327.
working pressure of, 1330.
Boker & CSo.*s wire, properties of,
202.
Bolt and nut machinery, power
required for, 1522.
Bolts, strength of, 1431.
Bonded joints and rails, rel. value
of, 780.
rails, electrolytic action on, 855.
Bonding car tracks. 771.
condition of track. 800.
third rail. 778.
Bonds, efficiency of, 781 .
requirements for. 775.
resistance of, 776.
testing rail, 801.
tests of, 773.
types of, 772.
Booster calculations for railways,
810.
characteristics of, 813.
comparison, 897.
controlling discharge by, 889.
D.C. type, 435.
definition of. 602.
diagram. 810.
for street railwasm, 807.
shunt and automatic types of,
OVa.
1516 POWER REQUIRED TO DRIVE MACHINERT, ETC.
Power ]t«qiilr«d f«r Machiae T—lm—Wk^mmltB mi V««ik
Teatw of Va»rlo«« MacMmo VooU.
(From a paper road by F. B. Duncan befora the Engineen' Bociely of
Western Pennsylvania.)
£^aufB L^THia.
16 in.; motor power required, approximate, 2 H.P. at maximum.
18 in. X 6 ft.; motor power required, 2.1 H.P.
36 in. X 10 ft.; motor power required, 10 H.P.
Plambbs.
10 X 10 X 20 ft. ; 3 toole, f X ^ in. cut; cutting speed, 18 ft.: pteafec
40-ton iron casting. H.P. required for cut, 26.5: lor return. 23.0; for re-
verse, 42.9. Ratio return, 3 to 1. Motor, 30 H.P., belted to eountenhaft.
8 X 8 X 20 ft^ 3 tools, f X i in. cut; cutting speed, 18 ft.; planing 324ob
iron casting; H.P. for cut, 16; for return, 14-8; for revene, 38.2. Batio
return, 3 to 1. Motor, 25 H.P., belted to countershaft.
66 X 60 in. X 12 ft.; 2 toob i^X 1-16 in. out; cutting speed, 21 ft.; piss-
ing 4 ton open hearth casting. H.P. required for out, 10; for retain. 14; kr
reverse, 16. Ratio return, Sf to 1. Motor moxmted on planer »i#*w»»»g vith
42-inoh 1,500-pound flywheel, running at 400 revolutioos, moanUd as
motor shaft; flywheel used as driving pulley for return of platen.
28 X 52 in. X 6 ft.; 1 cutting tool, f X f in. cut; cutting speed, 22 fL;
planing 3-ton iron casting. H.P. required for cut, 3.1; for retumt3.8: tor
reverse, 4.4. Ratio return, 4 to 1. Motor, 3 H.P., 800 revolutions. Aw-
age load on motor, 2.48. Flywheel, 30 in. diameter, 400 pounds, 800 revo-
lutions, mounted on motor shaft and used as pulley tor return of platen.
MnCELLAKBOTTS.
26 in. Oisholt turret lathe: machining Tropenas cast steel weight, 40O
pound; sise cut, one tool, f X 6-16 in.; 4 tools, | X 5-64 in.; weight castor
400 pounds; power for cut, 3.9 H.P
21 in. drill press; power required, 1 H.P.
5 ft. radial drill; nOaximum power required, 2.03 H.P. Motor used. 2 H.P.
600 revolutions.
Double and emery wheel stand M;wo 18 X 2 in. wheels, 050 rev.; 2 bboren
rinding castinn; maximum H.P., momentarily, 6; average, 3JS. Motor.
H.P., mounted on grinder shaft.
10 ft. boring and turning mill; cutting tools, 2; cut. f X 1-10 in.; eottiag
speed, 20 ft^ machining 3i5-ton casting; H.P. required for cut, 8.6. MoStf
used, 12 H.P.
Blotter: out, | X 1-10 in.; speed of tool, 20 ft.; machining open hesrtb
steel castings; power required, 6.08 H.P.
Flat turret lathe; H H.P. motor required.
Gisholt tool grinder; speed, 1,600 to 1,800 rev.; power required. 7 far
short periods, 4 on average. Motor used, 5 H.P.
The figures given in the following table for the power required to rm
the planing machines empty, do not include the t»^V<i«w«* horse-power sS
the instant of reversal, but represent the average forward and jetum of the
empty table.
POWER REQUIRED FOR MACHINE TOOLS. 1517
Results of tests at the Baldwin Locomotive Works, Philadelphia :
Kind of
Maohinea
Wheel lathe
Wheel lathe
Wheel lathe
Soring mill
Soring mill
Blotter .
Planer .
Planer .
Planer .
Planer .
Planer .
Planer .
Wheel lathe
Radial driU
Boring mill
Boring mill
Blotter . .
Siie.
84 in.
84 in.
84 in.
78 in.
78 in.
3d in. X 12 in.
62 in. X 35 ft.
62 in. X 35 ft.
36 in. X 12 ft.
24 in. X 13 ft.
36 in. X 18 ft.
56 in. X 35 ft.
56 in. X 24 ft.
90 in.
42 in.
4 ft. 6 in.
5 ft. 6 in.
40 in. X 15 in.
19 in. str.
Material
Gut.
Cast iron
Cast iron
Cast iron
Cast iron
Cast iron
Wrought iron
Wrought iron
Wrought iron
Wrought iron
Steel
Wrought iron
Wrought iron
Wrought iron
Cast steel
Cast steel
Cast steel
Cast iron
Wrought iron
Wrought iron
.S
I
2
2
2
1
1
1
2
2
2
2
2
2
2
2
1
1
1
1
1
Horse-Power.
1.5
1.4
2'.7
1.95
3.2
4.6
4.56
1.43
0.96
2.1
1.6
1.8
1.3
1.5
^5
11
5
3
4
4
Total Cutting.
Min.
9.9
6.0
2.1
1.1
2.4
2.4
2.2
1.8
2.9
4.2
5.3
4.3
5.5
4.4
20.6
23.0
11.3
Max.
13.0
16.0
4.2
4.8
7.9
5.8
6.2
4.7
7,1
6.7
21.6
26.0
13.8
13.7
17.7
4.8
9.7
Ave.
6.1
5.1
5.8
4.5
6.5
5.3
21.1
24.5
12.5
8.0
16.7
13.3
16.8
6.38
2.1
4.6
4.4
7.3
7.3
Results of tests, in ten differoat plants by C. H. Benjamin, to determine
the proportion of power absorbed by the counters, belting, line shaft, etc.
Useful
Friction Horse-Power.
Horse-
power.
Nature of Work.
Per 100 ft.
of Shafting.
ii
h o
.205
Per
Bear-
ing.
Per
Coun-
ter.
.538
Per
Belt.
•
1
Per
Man.
Boiler shop
4.77
.04
.550
.477
.310
.877
Bridge work . . .
8.28
.137
.04
.337
.606
.521
.164
.142
Heavy machinery. .
5.70
.233
.038
.581
.665
.453
.707
.160
Heavy machinery. .
8.55
.306
.06
.799
.600
.475
.627
.342
Average ....
5.57
.220
.044
.567
.602
.481
.452
.380
Light machinery .
2.76
.276
.034
.204
.155
.095
.790
.099
Small tools . . .
8.00
.400
.09
.689
.127
.119
.109
.152
Small tools . . .
2.49
.233
.03
.240
.121
.113
.881
.227
Sewing machines .
4.36
.430
.05
.397
.269
.208
.180
.204
Sewing machines .
5.08
.134
.034
.406
.172
.154
.181
.093
Screw machines . .
6.33
.381
.05
.633
.291
.235
.296
.396
Average ....
4.83
.309
.048
.428
.189
.154
.406
.195
For,
togeth<-
total thus uuMNuvxj. A.iix> BiBv ui uHjiiur will uepcou upuu <«ae ^way tne ZDa-
ohines are worked — i.e., cutting speed, feed, material cut, and whether mod*
em air-hardened tools are used; also to what extent machines are to operate
simultaneously. The larger the group the smaller the motor relative to
total power.
1540
INDEX.
Canning industry, deetrie hoat in*
1270.
Caoutchouc, spec. ind. cap. of, 36.
Capacitance of transmiasion circuits,
240.
Capacity and induotanoe, neutrali-
sation of, 292.
curves of railway motors, 676.
definition of, 5.
distorting efifect of, 1070.
effect of line, 264.
eleotroetatic, measurement of. 40.
Gott method, 326.
Kelvin method, 326.
loss of storage batteries, 881.
measurement of, 63.
meas. ooef . of induction by, 65.
measures of, 1409.
of A.C. circuits, 250.
effect of, 1216.
of battery for given discharge, 000.
of cables, direct discharge method,
325.
Gott's method, 326.
meas. of, 324.
Thomson's method, 325.
of gases, spec, inductive, 35.
of liquids, spec, ind., table of, 37.
of railway motors, 673.
' of solids, spec, ind., table of, 36,
37.
of storage batteries, 874, 883.
of telephone cables, 10^5.
of transformers, choice of, 458.
table of. 498.
of transmission circuits, 248.
of various overiiead transmission
lines. 250.
per 1000 feet of aerial wires, table
of, 252.
reactance, 259.
reactance of transmission oircuitn,
248.
spec, ind., measurement of. 38.
susceptanoe of transmission eir>
cults. 249.
susceptanoe, table of, 269.
symbol of. 8.
tests for locating breaks in cables,
327
Capacity tests with Lord KcbU
dead-beat voltmeter, 320.
unit of, 4.
Caroel lamp. 530.
Oar bodies, weight of, 734
body, preparatioo of. 745.
controllers, 753.
eneisy oonsumption per, USA.
input to, 657.
equipments, 613, 752.
heaters, cross seat type, 12SS.
hints to parehasem of, 13fi-
truss plank type, 1207.
heating, oost of, 1266.
electric, 770, 1205.
lighting, Q. E. railway ayibm,
851.
motors, installation of, 745.
test of, 392.
tests, intenirban, 722.
wiring, 746.
for heaters, diagram of, iVt.
special cables for. prop, of, ITS.
WesUni^ouse railway syvtra,
846.
Carbide fumaoe. King, 1245.
Carbon brushes, curreat density fa.
442
res. of, 362.
use of. 351.
Carbon dioxide, spec. ind. cap. of, S^
disulphide, spec. ind. cap. of. 35.
dust, 578.
effect on steel of. 826.
monoxide, spec. ind. cap. of, 35.
spec. res. of, 132.
Carbons for enclosed are Uunp*.
578.
for search lights. 579, 1125.
resistance of. 577.
sises of, 578.
test of are light, 577.
Carborundum, production of. 1345
Care of storage batteries. 123S.
Carey-Fos^r method, meas. ns- ^T.
58.
Oarfaart-CIark cell. dee. of. 19
Carpenter's throttling cBloriiaettr>
1395.
carves, 1309.
^
IND£X.
1541
!3Wri>eDter*s throttlioc Calorimeter,
directions for lue. 1395.
CtauTsdnc capacity of armature con-
ductors. 375.
of fusee, 1275.
galv. iron wire, 34.
of lead covered cables, 213.
off rubber ins. cables, 210.
of 'Wires, 208.
Oan, bucking of, 806.
depreciation of, 770.
dimensions of electric, table of,
732.
emersency braking of. 731.
energy required for, 079.
UghUng of, 806.
power required for, 656.
speed and energy curves for, 680.
Oartridge fuses, 1276.
Oarty bridging bell. 1102.
Gaacade, cap. of oondensera in, 324.
Oast iron magnet shoes, 352.
permeability of, 89.
pbys. and elec. prop, of, 137.
test of, 1294.
water main, electrolytic action on,
854.
Gastner metallic sodium cell, 1242.
process, caustic soda by, 1240.
Castor oil, spec. ind. cap. of. 37.
Cast steel, permeability of, 89.
rope, wire, 1325.
Catenary trolley, bridge for, 648.
construction. 639.
material for, 643.
Cathode, definition of. 1229.
rays, theory of. 1248.
Caustic soda, production of. 1239.
Cell, Burnley type. 18.
Oarhart-Clark type. 19.
chloride of silver type, 16.
Edison-Lalande. des. of. 17.
Fuller, description of, 16.
Gasner type. 18.
grouping, efficiency of, 21 .
LeoUneh^. des. of. 16.
standard, construction of, 11.
description of, 19.
spec, for, 10.
Weston oadmium type, 19.
Cells, Clark type, 19.
closed circuit, table of, 14.
grouping of, 19.
open circuit, 15.
CeUuvert, spec. ind. cap. of, 36.
Cement, adhesion to bricks <rf, 1294.
and sand, fineness of, 1294.
crushing load ci, 1322.
hydraulic, strength of, 1294.
mortar, 1293.
Portland, strength of, 1294.
wt. of, 1293.
Rosendale, wt. of, 1293.
strength of neat, 1294.
Centering of armature, 403.
Center of gravity of distribution
system, 277.
pole line construction, 631.
Centi-ampere meter, balance used
as, 43.
Centigrade vs. Fahrenheit scale,
1508.
Centimeter, definition of, 2.
Central battery system, 1096.
energy system, 1096.
office apparatus, 1104.
offices, adv. of one vs. several,
1094.
R.R. of N J. shops, power to run
tools in, 1520.
station battery connections, 899.
electrically operated switch-
board. 928.
lightning arresters in, 983.
switchboard panels, 907.
three wire battery system, 903.
vs. isolated plant, 1286.
telephone office, 1089.
Centrifugal tension in Manila ropes,
1491.
C.G.S. units, 2.
names of, 6.
Chain, 1496.
coil. 1496.
proof, 1496.
short link. 1496.
weight of. 1496.
Characteristic curve, external
dynamo, 337.
of dynamo, plotting of, 382.
r
1542
INDEX.
CSiaracteristio curve of N.Y.C. looo-
motive. 742.
of railway motor. 664.
curves of overoompounded
dynamo. 340.
of solenoids. 120.
Characteristios of electromagnets.
129.
of G.E. single-phase motor, 713.
of railway booster, 813.
of railway motors, 685.
of transformers. 483.
of two-path armature winding,
348.
of Westing^ouse single-phase
motor, 715.
Charooal rope, wire, 1325.
Charge curves, storage battery, 876.
of storage battery, loss of, 884.
rate for batteries, 883.
Charging batteries, 482.
batteries, connections for, 899.
current of line wave, 249.
per 1000 feet of aerial circuit,
253.
of storage batteries, 880.
Chart for calculating A.C. lines, 282.
ot parabolic curves in wire spans,
218.
Chase-Shawmut fuse wire, 1275.
Chatterton*s compound, specifica*
tions for, 194.
Checking preliminary dynamo di-
mensions, 363.
wattraetera, 72.
Chemical action in cells, 14.
equivalent of elements, 1230.
properties of rubber, 229.
qualities of steel for third rail. 822.
(^himney construction, 1339.
weight for burning given amounts
of coal. 1342.
protection, 1281.
rate of combustion due to height
of, 1342.
tables. 1338.
Chimneys. 1338.
dimensions and cost of, 1343.
draught power of, 1338.
Iron, dimensions and cost of. 1344.
Chimnesm. necessary bei^t of. 1342
radial brick. 134L
and bond. 1340L
flise of, 1338.
steel, foundations for. 1343.
lining for.* 1343.
plate, 1343.
Chloride of silver eell. 16.
Chlorine in electrolyte, test for, ^
Choke coils, mountlnsof, 984.
S.K.C. arrester, 991.
use of, 994.
Choking effect of inductance, 1079.
Chord of polar are, x'alues of. 371-
of pole face, dimensions ctf . 36^
Chrome-bronse, phys. and elee. profi.
of, 135.
-steel, phys. and elec prop, of, 135.
Chronc^craphs, types of. 1128.
Chronoscope, Schults, 1130.
Circuit breaker, def . of. 523.
design. 952.
Westinghouse oil, 960.
Circuit breakers, capacity of. 953.
for booster protection, 952.
for motors. caiMcity of, 955.
for protection of transmismn
line, 951.
for railways, use of, 789.
for storage battery protectJOB.
952.
grouping of, 929.
leads for, 975.
mounting of, 912.
oil. arrangement of. 935.
polyphase motors protected by.
954.
rating of. 506, 912.
specifications for, 947.
table of. 949.
Circuit closer, torpedo, 1139.
trunks, operation of. 1095.
Circuits in buildings, ins. res. of, 85.
laws of electrical, 55.
multiple, res. of. 55.
testing drop in railway, 804.
tests (^ street railway, 796.
Circulating pumps, 1445.
Citjes, electrical distributioo in, 361.
mill poww in various, 1^12.
INDEX.
1543
Clark cell, description of, 19.
CM.F. of. 5.
method, compariaon of E.M.F. by.
77.
testing Joints of cables by, 323.
Clflty conduits, conatr. of. 301.
foundations on. 1200.
C3earins-out drops 1000.
CSoaed oars, weiglit of, 734.
eirouit cells, table of, 14.
Coal, American, heating value of,
135a
and electric heating compared.
1265.
anthracite, siiing tests of. 1354.
approximate analysis of, 1352.
consumed by isolated plant, 1286.
sas, analysis of, 1510.
candle power of, 1450.
spec. ind. cap. of, 35.
heating value of, 1340.
power, data on, 869.
space to store, 1353.
value of in weight of woods, 1349.
weight per cubic foot of, 13.53.
Gbalfl, relative value and how to
bum, 1355.
Cbast-defense board, recomm. of,
1123.
guns, manipulation of. 1134.
Ooasting, formula for, 668.
line, location of, 668.
Goooa and coffee dryers, electric.
1270.
Codes, telegraph. 1052.
Coefficient of induction, meas. of, 65,
of Induction, symbol of, 8.
of self-induction, 64*
def . of, 238.
formula for, 405
of temperature of metals, 133.
Coefficients of expansion of solids.
1608.
of magnetic leakage. 376.
of reflections, 593.
Coercive force, def. of, 108.
Coffee and cocoa dryers, electric,
1270.
Coherer, 1058.
receivers, 1064.
Coherers, mercury auto, 1066.
Coil chain, 1496.
slots, design of armature. 358.
trial armature, 373.
surface of field magnets. 352
Coils, armature, placing of, 358.
for transformers, 444
heating of. 127.
values for number of armature.
373.
winding of, 112.
Coke, analysis of. 1353.
space required for. 1353.
weight per bushel of, 1353.
Collier A Sons' factory, heating
devices in, 1270.
Columns, comparison of water. 1463.
hollow. 1305.
cylindrical. 1306.
pillars or struts, 1300.
solid cast iron, 1305.
strength of white pine, 1319.
solid cast iron. 1305.
tests of cast iron. 1306.
ultimate strength of. 1306.
wrought iron, ult. strength of,
1307.
Colza oil, spec ind. cap. of, 37.
Combinations of railway motors,
760.
Combined volt and ammeter method,
meas. A.C. power by, 71.
Combustibles, properties of, table of,
1348.
Combustion, draught necessary for,
1342
Commercial efficiency curve for arc
dynamo, 338.
efficiency curve for motora, 370.
of dynamos, def. of, 383.
lights, burning of. 611.
rating of railway motors. 675.
transformers, 445.
Committee on Notation, table by, 6.
Common battery system, 1006. 1115.
signaling battery system. 1115.
trunks, 1096.
Commutated rotor windings, 429.
Commutating machines, def. of, 503.
sone, 350.
1544
INDEX.
Gommutation in dynamoB, 364.
Commutator bare, number of, 361.
brushes, sparking at, 805.
brush friction, meas. of, 508.
diam. of, 361.
rise of temperature of, 362.
segments, number of. 361.
type, D.C. meters, 097.
Gommutatore, construction of, 351.
Comparative cost of gas and elec.
cooking, 1260.
expense of operating transformers,
458.
values of lighting methods, 594.
Comparison of copper and aluminum
wire, 195
of interurban car tests, 724.
Compensated A.C. motor character-
istics, 713.
revolving field alternators, 409.
Compensation for power factor,
1002.
method, E M.F. of batteries, 62.
Compensator potential regulators,
def . of, 503.
use of starting, 918.
Compensatore, construction of, 463.
for induction motors, 429.
Composite electric balance, 43.
Compound cables, design of, 331.
dynamos, characteristic of, 340.
des. of, 336.
regulation tests of, 382.
engines, cylinder ratios for, 1441.
Compressive strength of woods, 1317.
Concealed lighting 83^tem, 601 .
Concentric cable, capacity of, 251.
Concrete foundations, 1292.
manholes, cost of, 303.
reinforced, 1292.
sub-foundations, 1292.
Condensation in steam pipes, 1415.
in steam pipes aboard ship, 1415.
Condenser capacities, ejector, 1445.
current, curve of, 1219.
diagr. of connections of, 39.
method, res. of batteries by, 60.
unit, 5.
Condensere and pumps, 1443.
construction of. 38.
Gondensen. cooling water by, 144L
design of, 35.
in caecade, cap. of, 324-
in parallel. 63.
cap. of, 324
in series, 63.
cap. of, 324.
losses in, meas. of. 513.
Condensing engines, number of
expansions in, 1441.
Conductance, definition of, 9, 55.
of multiple circuits, 55.
^rmbd of, 8.
Conducting power of sulphuric acil
table of, 905.
Conductivity, definition of. 9.
Matthiesaeo's staad. of, table of.
132.
millivoltmeter meas. of, 87.
Northrup method of, mea&, 60.
of cables, meas. of, 390.
of conductors, taUe of. 132.
of copper, 518, 910.
of dielectrics, epeoifie tJiemuil
234.
percentage, form, for, 132.
relative, 132.
specific 132.
symbol of, 8.
Conductor rail. Potter type, 830.
Conductors, carrying cap. of arma-
ture, 375.
dimensions of, 260.
economical tapering of. 279.
for electric railways, overbesd.
785.
for hi^-tension, insulation d.
939.
for high-tension transmission. 235.
for parallel D. C. sjretem, ^xe of.
284.
for railways, dimensions of, 791.
installing, U. S. Navy, spec. for.
1170.
isolation of, 936.
per K. W. del'd, curves showing
weight of copper, 283
res. of. 61.
rotation around pole of, 109.
spec. res. of, table of, 132.
INDEX.
1545
tonduit. Board of Trade regulations
for, 783.
cx>nstruotioii, U. S. Navy, 1170.
ooet> of efttimating, 317.
itexnised, 310.
total, 307.
def . of, 301.
foot, cost per manhole of, 304.
cost per, table of, 306.
in cities, cost per, table cf,
307.
laying of. 301.
multiple duct, oonstr. of, 301.
New Orieana, 306.
aysteiDB, heat diasipation in, 214.
railway, 835.
'work, usual practice of, 302.
Oonduits, Ghicago, underground,
ooBt of, 317.
ooet of, 302.
monolithic, des. of, 301.
multiple, adv. of, 301.
siDgie duct, adv. of, 301.
Connecting transformers to rotary
converters, 476.
C3oaneotion ci batteries, 10.
Connections of polyphase meters,
checking of, 1026.
of transformers, 207, 472.
on switchboards, 910.
Connectors, Seeley's cable, 190.
Consolidated car heating, wiring
diag. of, 1267.
Constant current booster system,
diagram of, 901.
current from constant potential
transformers, 464.
current machines, regulation of,
513.
current transformer panels, equip.
of, 922.
current transformers, G. E. type,
464
galvanometer. 23.
hysteresis, wattmeter test for, 102.
potential arc lamp, 674.
machines, r^^lation of, 513.
secondary current, transformers
for. 462.
Constantin wire, properties of. 202.
Goostants for barrel armature wind-
ing, 376.
hysteretio, table of, 99.
of meters, values of, 1029.
Construotion of ohinmeys, 1339.
of manholes, <$ut8 of, 309.
power station, chart of, 1280.
tools, deetrio work, 1530.
Consumption of eneigy of cars, 652.
of eneigy of eleo. heaters, 1265.
Contact buttons, Westlnghouse
railway system, 844.
plates, Westinghouse railway
system, 841.
Contactors, multiple unitsyston, 762.
Continental code, 1052.
Control of lights from two or more
points, 294.
of motors. Ward Leonard's sys-
tem, 354.
of water-tight doors. 1198.
Controller, care of, 747.
combination, 760.
for oil circuit breaker. 975.
series-parallel, 753.
Controllers, dimensions of. 757.
G.E. railway system. 851.
installation of, 746.
dontrolling desks. 941.
discharge, methods of, 888.
panels. Navy spec, for, 1185.
pedestal, 940.
switchboards, 940.
ConvectorB and radiators, 1263.
Converter armature windings, 441.
definition of, 508.
panels, three-phase rotary, equip,
of. 919.
Converters connected to transform-
ers, 477.
rotary type, 436.
Conveyors, ammunition, U. S.
Navy, 1193.
Cooking apparatus, electric, effi-
ciency at, 1260.
electric, cost of. 1259.
gas and elec. compared, 1260.
record, daily electric, 1262.
utensib. electric, cost of operating,
1261.
1546
INDEX.
Cooling surface of field ooils, table
of, 352.
tower test, 1447.
of transfonners, 448.
water for condenBera, 1443.
Cooper-Hewitt mercury lamps, 558.
Copper, admixture of, eflfeet of, 144.
and aluminum compared, 195.
and brass wire and plates, weight
of. 1324.
bar data, 911.
bars on switehboardA, 909.
brushes, current density for, 442.
res. of, 362.
use of, 351 .
conductivity of, 518, 910.
electric welding of, 1272.
electrolytic re6ning of, 1235.
for A. G. lines, table for oalo. of.
279.
fusing effect of current on. 217.
in railway feeders, 791.
loss in alternator armatures, 407.
in transformers, 445.
in transformers, meas. of. 487.
in transformers, Sumpner's test
of, 497.
in transformers, taUe of, 498.
melting point of, 143.
phys. and elee. prop, of, 135.
plating, 1233.
res. of cables, meas. of, 330.
rise in resistance of. 379.
spec. res. of. 132.
strands, stand, prop, of, table of,
159.
temperature coefficient of. 133.
527.
weight of, 143.
of round bolt, 1323
wire and plates, 1324
fuses for railway circuits, 731.
Matthiessen's form. for. 133.
phys. const, of, 143.
res. of, table of, 148.
skin effect factor for, 238.
solid, G. E. Co., prop. of. table
of. 162.
solid, table of. 154.
stranded, table of, 155.
Copper wire tables. A I££., lH
tables, explan of. 145.
tendle strength of. 150.
weight of. English system, takit
of. 157.
weifl^t of, naetrie ayetaoi, taik
of, 158.
Core disks for amaatareB, 356
insulation, armatare, 341.
losses, 98.
in armature, 300.
m tranaformera. 445.
in transfomMn. oompantm
455.
in transformeiB, earves of. 4Si
456.
in transformers, meas. of. 485
in transformers, table of, 4K.
loss test, 383.
of stator and rotor, 425.
of submarine cables, deai8:n of. SI-
of three-phase transformaB. 47QL
type transformeis, ooSs for. 444.
Cores, cross section of. 385.
field magnet, general data od, 352.
magnetic densitleB for tiaiulQ^'
mer, 447.
of armatures, data on, 357
of American transf ormen, typm
of. 443.
Corey telephone system, U. 8. Navy.
1209.
Com plaster transmitters, 1074.
Cos a, values of, 276.
Cost of aluminum wire, 105.
of oondult, 302.
estimating, table of, 317.
itemised teble of. 316.
total, 307.
of oooking daily meal by dec,
weekly record, 1262.
of duet mat^ial in place, table of,
307.
of electric car heating, 1260.
of 5^ X 5^ X r manhoks. 316.
of heating water by eleetiieity.
1259.
of Inoandeseent lamps, 556.
of manhole, estimating, table o(
317.
INDEX.
1647
3ost of manholes, table of, 302.
of one mile of trolley system, 629 .
off operating electrie cooking
uteunls, 1250, 1201.
electric devatora, 1628.
elee. heaten, 1265.
dec. irons, 1263.
lamps, 554.
of paving per sq. 3^., 305.
off power, curves for reducing. 868.
of protected third rail, 835.
off sewer connections, 303,
of street excavation per conduit
foot, 306.
of telephone plant, 1108.
of tools and supplies for installing
electric work, 1531.
per conduit foot for manhole, 304.
per conduit ft. in cities, table of,
307.
per conduit foot, table of, 306.
Costs, comparative, gas and elec.
oooldng, 1260.
Cotton covered wires, linear space
occupied by, tables of, 121-126.
RMudilnery, power to drive, 1524
Coulomb, definition of, 5.
international, def. of, 9.
value of, 8.
Counter cells, use of, 891.
e.m.f. cells, use of, 891.
e.m.f. in motor armatures, 353.
torque, meas. of, 396.
Cove-lighting, 592.
Cover for service boxes, cut of.
315.
Coven for manholes, cuts of, 313-
315.
Cowles furnace, 1247.
Crane chain, 1496.
Cranes, boat, Navy spec, for, 1194.
power to run electric. 1527.
Cross connections, use of, 1104.
seat heaters, wiring diag. of, 1268.
section of field core, 365.
of conductors, calc. of, 277.
of conductor, formula for, 265.
-talk, definition of, 1081.
elimination by transposition of,
289.
Croeses in cables, location of, Ayrton
method, 327.
Croflsinffs of wires, 639.
Crushing loads for brick, stone,
mortar, cement, 1322.
strength of woTxls, 1316.
Cubic feet table, water h. p.. 1475.
Current canying capacity of lead
covered cables, 213.
carrying capacity of rubber ins
cables, 210
carrying capacity of wires, 208.
curve for railway motors, 669.
definition of, 502.
densities for transformer coil, 447 .
for various brush- materials,
442.
density at brush faces, 361.
for brushes, 351 .
for commutator segments. 861 .
distribution by railway oonduc-
tora, 79U
in cables, max. allowable, 212.
in multiple circuits, 55.
in three-phase circuit, meas. of,
406.
maximum, A. C. windings, 127.
mean, A. C. windings, 127.
measurement of, 41.
millivoltmeter meas of, 78.
of altematons, 405.
potentiometer meas. of, 47, 63.
swapping, 859.
taken by induction motom, 297.
by lamps, 542.
transformen, descr. of, 945.
unit of, 4.
variations on water main, 857.
voltmeter meas. of, 77.
wave form of, 49, 1218.
Currents, fusing effects of, 217.
Curtis steam turbine, 1455.
Curvature of rails, 616.
Curve drawing meter, G. E., 1036.
dynamo magnetisation, 336.
magnetic distribution, 340.
tracer, Rosa tsrpe, 50.
Curves, altem. current power, 70.
railway, 612.
formula for, 665.
r
1548
INDEX.
Curvw, trolley wire, 638.
voltage of storage batteries, 883.
Cut-outs, slate, res. betw. terminals
of, 86.
Cyanide of potassium, production of,
1246.
of sodium, production of, 1246.
Cycles, measurement of, 50-54.
Cylinder ratios, compound engines,
1441.
lastly electric cooking record, 1262.
Damping of oscillator, 1059.
D. and W. fuses, 1276.
DanieU cell, 14.
D' Arson val galvanometer, 21.
galvanometer, des. of, 25.
m. of, 25.
Data for transformer tests, 495.
Davy cell, 14.
Decade resistance box, 32.
Decane, spec. ind. cap. of, 37.
Deceleration, formula of, 668.
Deck beams, 1314.
winches, 1106.
Decylene, spec. ind. cap. of, 37.
Defensive mines, 1 137.
Definite time limit relays, 956.
Definition oS symbols, dynamo
section, 334.
Deflection of beams, 1309.
Deflections of aluminum wire in
still air, 226.
De Laval steam turbine, 1452.
Ddta connected armature winding,
413.
connection of transformers, 473,
478.
of winding, 404.
Demand meter, Wright, 1008.
Density of field magnet cores, mag*
netic, 365.
of armature teeth, 367.
of electrolyte. 877. 884.
of pole faces, magnetic oalc. of,
356.
Depolariser, def. of, 14.
DeixMit. rate of, 1235.
Depreciation of isolated plant, 1285.
of telephone plant, 1106.
Depreciation of streei nilmjs, tahk
of, 770.
Depth of armatare coil skua. 3*3^
Derived geometric units, 2.
mechanical units, 2.
units, symbols of, 1.
Design of circuit breakets, 953.
of transformers. 447.
Designing dynamos, 370.
of dynamos, princtpies of, 355.
Destructive effect of tieetnijm
854.
Detectors, eieotioljrtic, 1067.
hot-filament, 1068.
low resistance, 1065.
shunted, 1065.
magnetic, 1067.
Deterioration of onderinmund mccak,
852.
Determination of RKMsture to steua.
1304.
of wave form, 49.
Diagram of car heating wiring, 13Cr.
of car wiring, 747.
of cdls in multiple, 20.
of train performance, 083.
Diameter of commutator, 361.
Dielectric strength ci air. 233.
strength of insulating materiab
228.
strength, test of, 515.
tests of cables, 332.
Dielectrics, properties of, 227.
puncturing voltages for, 238.
specific inductive capacity of, 227.
thermal conductivity of. 234.
variation of resistance of, 228.
Difference of elevation, potental
strains due to, 981.
of potential, meas. of, 75.
symbol of, 8.
unit of, 4.
Differential ammeter, use of. 900.
galv. method, res. meas. by, 5fl.
gear, turret turning system. 1190.
Diffused lighting system. 002.
Diffuse reflaotk>n, coef. of, 596.
Diffusion of light. 500.
Dilute sulphuric add, eooduccing
power of, table of, 905.
INDEX.
1549
liKate sulphuric add, reaiBtanoe of.
1229.
strength of, table of, 904.
Hzn^nsioiis of oonduotora, 260.
of oontrollen, 767.
o£ djrnamoe, preliminary, oheck-
ins of, 363.
of electric can, table of, 732.
of physical quantities, 6.
of railway conductors, 791.
of storage battery, 883.
Mp in span wire, 634.
[>irect^eonnected generating sets,
standards, 1435.
oontrol panel switchboard, 906.
cu.rrent arc lampe, 568.
fsireuit breakers, design of, 052.
circuits for operating oil
switches, etc.. 939.
distribution, pressure for, 260.
distribution, sise of oonduo-
tore for, 284.
dynamos, Hopkinson's test of,
303.
exciter switchboard, 942.
feeder panel, equipment of, 928.
generator panels, equipment of,
024.
meters, testing of, 1020.
motor panel, equipment of, 928.
motors, counter e.m.f. in, 353.
over voltage relay, 960.
reverse current circuit breaker,
050.
rotary, converter panel for, 925.
system, examples of, 271.
use of in U. S , 870.
deflection method, ins. res. by,
321.
discharge method, meas. cap. by,
63,325.
reading ohmmet^r, 57.
potentiometer method, E.M.F.,
of batteries, 63.
Discharge, chemical effect of electric,
1232.
curves, storage battery, 875.
methods of controlling, 888.
points for lightning rodff, 1282.
rate of storage batteries, 874, 883.
Dischargers, static, 092.
Discharges, atmospheric, 1278.
Disconnecting switches, 965.
arrangement of, 933.
between bus bars, 929.
Discount meter, Wri^t, 1008.
Disinfecting sewage, 1244.
Disks, armature core, constr. of, 34 .
armature core, data on, 356.
Disk type armatures, 341.
Disruptive strength of tranftformer
insulation, 483.
Distance-time curve, 668.
Distributed coil form of winding,
410.
signal block S3rstem, 627.
Distributing cables, 1083.
frames, 1104.
Distribution curves, 540.
light, 599.
system, parallel, 277.
for single-phase railway, 718.
systems in general, 262.
Distributive shunt telephone sys-
tem, 1107.
Ditches, constr. of, 868.
flumes and, 1468.
Divided bar method, determ. magn.
values by, 92.
Diving-lanterns, 1179.
Domestic illumination, 596.
Dossert joint, 191. 910.
Double bridge, Kelvin type. 59.
current generator, def . of, 502.
use of, 440.
galv. iron telegraph wire, proper-
ties of, 200.
square roots, table of, 45, 46.
track pole construction, 631.
truck cam, power for, 656.
Draft power for comb, of fuel», 1342.
Drag on armature conductorn, 351.
Draw-bar pull, test of. 803.
Drawing in underground cables,
319.
Drill presses, power required for,
1521.
Driver-Harris wire, properties of.
202.
resistance of. 207.
1550
INDEX.
Drop at end of line, test of, 800.
ID A.C. lines in per cent, 280.
in candle-power of lampH, 544.
in overhead lines, 798.
returns, 798.
in pressure in parallel distribution
system, 1{79.
in railway circuits, test of, 804.
feedere. 791.
line, 794.
in secondary of transformers,
test of, 483.
in voltage at brush faces, 362.
at train, 795.
in nulway circuit, 796.
in storage cells, table of, 879.
max., U. S. Navy spec, for, 1171.
Drum armatures, 341.
windings of armature. 345.
Dry batteries, description of, 18.
cell, Burnley type, 18.
chloride of silver type, 16.
Gasner type, 18.
measure, metrical equivalents,*
1502.
Drysdale's permeameter, 97.
Duct, def. of, 301.
material in place, cost of, table of,
307.
Ductility of boiler plate, 1333.
Ducts, arrangement of, cuts of,
310.
heat dissipation in, 214.
in manhole, grouping of, 318.
Dudell oscillograph, 50.
Dumb-bell oscillator. 1056.
discharge oi, 1060.
Duncan meters, 998.
method, meas. of wave form by,
49.
recording wuttmetere, testing of,
1031.
Duplex loop 8y.Htem, 1047.
repeater, 1049.
telegraphy, 1044.
telephony, 1106.
Durability of railroad ties, 619.
Dust of carbons, 578.
Djmamo cable, flexible, table of. 172.
deaign, principles of, 355.
Dynamo cable, dimensMme. pw-
liminary. cheekinK of. 363^
efficieocics, averagie. taUe of. 37r.
efficiency, U. S. Navy. 115&
regulation, test for, 382.
room distributioo, U. S. Ksry.
diagram <^. 1165.
room, U. 8. Navy, 1153.
Dynamometer-. Siemaas* electn»-. 42.
Dynamos and motovs, pnnciplB of.
336.
and motors, tests of. 378.
classification of. 336.
design of. 370.
effieteney tests of, 3S3.
E.M.F. of, meas* of, 74.
in ships, gyrostatac aetkm on. 35S
insulation of. meaa. of. 83.
resistance of, workshop mecfaodL
61.
temperature riae in, 378.
U. S. Navy. spec. for. 1156.
Dynamotors, definiUcm of, 502.
description of, 434.
Dyne, definition of. 3.
connections, 782.
currents, effect of. 1081.
foundations on. 1291.
Ebonite, spec. ind. cap. of. 38. 227.
Economical tapering of oonduoton.
279.
EcoDomisers, fuel, 1378.
Economy coils, construction of. 463
of isolated electric plants, 1283.
of superheated steam, 1414.
£>idy current core kns testa, 383.
factors, table of, 106.
loss, formula for. 99.
loss, meas. of, 104, 508.
currents in armatures, prevention
of. 350.
currents in iron cores. 99.
Edison-Lalande cell, des. of, 17.
-Lalande cell, illustration cf. IS.
storage batteries. 1227.
three wire system, 355.
Effective E.M.F. of A.C. current.
404.
resistance of A.C. circuits. 236.
INDEX.
1551
lleot of line eapadty. 264.
fficienoies, average dynamo, table
of, 377.
Ifficiency curve of motora, 370.
eurve oi are dsmamo, oommeroial,
338.
eurve of arcUynamOftelectricai, 338.
curvee of railway moton, 686.
del. of, 507.
oeoerator, U. S. Navy, 1158.
of arc lights, 580.
of bonds. 781.
of cell groupinsB, 21 .
of dynamos, 370.
of djmamos and motors, meas. of,
507.
of dynamo, oalo. of, 301.
of eleo. cooking apparatus, 1200.
of gas engine, 1449.
of lamps, variation in, 547.
of large and small transformerH,
relative, 450.
of Moore tube, 566.
of motors. Navy spec, for, 1 185.
of motora, tests of. 394.
oi railway motora, 663.
of small pumps, 1368.
of steam boiler, 1320.
of steam engines, superheated
steam. 1414.
of storage batteries, 870.
of storage batteries, variation of,
004.
of transformera, 453.
of transformer, test of, 403.
of various types of steam engines,
1430.
tests of dsmamos, 383.
of dynamos and motora, 386.
of induction motora, 308.
of railway moton, 803.
of street railway motora, 307.
of two d. c. dynamos, Hopkin-
son's method, 303.
of two similar dynamos, Kapp's
method, 887.
Ejector condenser capacities, 14^.
Elasticity, modulus of, 1302.
Elastic limit. 1302.
lesilience, 1312.
Electrical and mechanical units table
of. 1258.
circuits, laws of, 55.
efficiency curve of arc dynamo,
338.
efficiency of dynamos, def . of. 383.
engineering symbob. 1.
units, 2.
load test. 305.
measuring instruments, 21.
prop, of alloys, table of, 134-140.
of metals, table of, 134-140.
of rubber, 220.
qualities of steel for third rail. 822.
Hjrmbols, 1.
units, 4.
international, 0.
Electrically operated central station
switchboards, 028.
Electric and coal heating compared.
1265.
and gas cooking compared. 1260.
and gas rates compared. 1261.
automobiles, 1224.
balance. Kelvin type, 43.
brake oontrollera, list of, 755.
car controllere, 753.
beaten, hints to purchasera of,
1260.
heating. 1265.
heating, cost of, 1266.
motora. installation of, 745.
care, dimensions of. table of, 732.
speed and energy curves for,
680.
circuits, ins. res. of, 85.
cooking apparatus, efficiency of.
1260.
cost of, 1250.
record, table of, 1262.
utensils, post of operating. 1261 .
cranes, power to run, 1527.
drive, saving by. 1520-
energy, def. of, 5.
ssonbol of, 8.
elevatora, operating cost of, 1528.
power used in, 1528.
equipment of one car, 752.
forge. Burton, 1274.
furnace, efficiency of, 1244.
1550
INDEX.
Drop at end of line, t«t of. 800.
in A.C. lines in per cent, 2^
in candle-power ol lamps, 544.
in overhead lines, 798.
retuma, 798.
in pressure in paralld distribuUon
system, Sf79.
in railway cirouits, test of, 804.
feeders, 791.
line, 794.
in secondary of transformers,
test of. 483.
in voltage at brush faces, 362.
at train, 795.
in railway circuit, 796.
in
max
Druin ^^ ^
windings of armature, 343. 4. ^^'^
Dry batteries, description ^v^\% » -
cell, Burnley type, 18. <^\ ^
chloride of silver typ«^
Gasner type, 18.
measure, metrical
1502.
DynaSftO
litaiJ
efBcleaci«*»
'^r
^\>^
•£t^
V-A**^- '^
DryHdale*8 penneam.eK4
1271.
/
Duct, def. of, 301.
material in place,
307.
Ductility of boi^
Ducts, arrange
310.
heat dissinr •
in manhoi '
Dudell osci: P
Dumb-bel* *
disci
Duncan steel, 1271
met^ >'y spec. for. 1210.
4 -ileal equivalents
re-
jchemi«t,y,geopeof 1231
^t«>^ynamometer 42
Jectl^lysis due to A.C.. 860
tn lower New York, is
near power house, 862. '
remedies for, 861.
rules for prevention of 7si
theory of, 852, 1229.
\
'*
«
%
cale
.,ir
13
^0. for.
exoitii*^ ^^ of, ^
flux <i^"^f 127
heatinJ? '^j<,n
kf**'"
J 1231-
plun««£s*; ^, 10»-
proper*' j^.
Pu/loT* ^^ ll<>-
tmctic^f ^; Jl2^p,c
Ryan t>rf^^ ^^>^^
ElectrT>m<;«»-^f >f
forplati "'^
INDEX.
155:^
<
".X-^-^-^lVv
«!>j.
V
* ■ - ^ - -
V
V
V
Energy and speed curve, eleotrio.
def . (rf, 5.
for eleotrio cars, approx. of, 079.
input to cars on grades, 657.
in three-phase circuit. 405.
kinetic, 3.
cf electric railway, 706.
potential, 3.
units compared with work units,
12.
■% foundation, 1292.
power required for, 1516.
'>8, U. 8. Navy, 1202.
^ ->Kof, 981.
specifications for.
<4^
V*
"^.j
^♦>
C;
a electric.
^ of cars, 731.
'latton of, 49.
• generation of, 350.
*on of, 336.
.0. current, discussion of, 404.
* batteries, comparison of, 76.
meas. of, 62, 74.
ot dynamos, meas. of, 74.
of standard cells, 19.
Enclosed arc carbons, 578.
arc lamps, 568, 575.
'uses, 1276.
motoni, navy spec, for, 1183.
kind ceW switches, 890.
n»e of, 890.
Endless chain ammunition hoists,
^.8. Navy, 1192.
Energy and speed curve, 680.
oonsumption of elec. heaters, 1265.
per car, 662.
dissipation in arm. core, 107.
remote control
•62.
a pii>es, 1418.
.), map of. 592.
of one car. 752.
wCric cars. 613.
.valent. electrochemical. 14.
values of elec. and mech. units,
1258.
Erection of batteries, 884.
Erg, definition of, 3.
value of, 12.
measurement of, 104.
Error of meas. in voltmeter testa, 76.
table for wattmetere, 1082.
Estimate of water, 860i
Estimating cost of conduits, table of,
317.
cost of manhole, table of. 317.
Ether, oscillations in. 1278.
Evaporation, factors of, 1401.
Evolution of conduit, 301.
Ewing's hysteresis tester, 102.
Excavation per conduit foot, cost of,
306.
Excessive voltage, evils of. 545.
Exchange current in transformer,
495.
systems, automatic, 1106.
telephone systems, 1088.
Exciter switchboard, D. C, 942.
Exciting current in transformer, 483.
in transformer, meas. of, 485.
in transformer, table of, 498.
1554
INDEX.
Ezdtinc power of electromagneta,
111.
Excitation current in tnuuformer*
meas. of, 485.
of field-masnets, 365.
of induction motors, 308.
Exide storaoe batteries, 1227.
Expansion, coefficients of, 1508.
of water, 1362.
Expense of operating transfonnerB,
458.
Expenses of telephone cables, 1087.
Explosions due to electrolysis, 859.
Explosives near railways, danger of,
863.
Exposure used in transposition, 288.
Extension bell, connections of, 1076.
External characteristic curve of
dynamo, 337.
characteristic curve of shunt
dynamo, 339.
resistance of cells, 20.
Externally controlled boosters, 894.
E3re beam foundations, 1293.
Eyes, effect of light on, 600.
Viacterlee, power consumption in,
1517.
Factors, eddy oiurent, table of, 106.
hysteresis, table of, 100.
Factors of evaporation, 1400.
safety, N. Y. City building codes*
1302.
Factory call bell system, 293.
Fahrenheit vs. Centigrade scale,
1508.
Fall of potential in railway return,
782:
Fans, effect of temp, of gases on
load. 1346.
for induced draft, 1345.
ventilation, navy spec, for, 1196.
Farad, definition of, 5.
international, def . of, 9.
standard, 38.
value of. 8.
Fatigue of iron and steel, magnetic,
455.
Faults in armaturm, tests for, 402.
in cables, location of. 328.
Faults in cables. Morrmy's methol
329.
in street caxs, 805.
in underground cables, locatioacf.
331.
Feeder circuit protectioa by w^ksK
950.
panel, D.C., equipment of, 0^
sin|^e-pliaae,jequipment far, 91&
three-phase, equip, d, 917.
two-pbaee, equip, of. 918.
potential regulator. G. £. type.
468.
regulator, G. £. t>'pe« 438.
Feeders, arrangement of, 78f>.
capacity of, 786.
classes of, 788.
design of, 787.
load on, 787.
regulation of, 513.
Feed-water heaters, 1375.
heating by pump exhaust. 1377.
pipes, sises of, 1373.
saving by heating, 1376.
saving in fuel by healing, 1377.
Ferro-niokd wire, pn^Mrties of. 202,
207.
Feet per minute in miles per hour,
660.
to centimeters, 1503.
Fibre, specific inductive capacity
of, 227.
Field busier, 1140.
coils, cooling surf aces of, table of.
352.
heating of, 352.
resistance of, 401.
frame of induction motor, slots in.
426.
intensity, value of, 7.
magnet coil surface. 352.
cores, design of, 365.
excitation, 365.
windings, 369.
magnets, ampere turns in, 366.
design of, 364.
general data on, 352.
use of various types of. 355.
rheostats, electrically dontroQed,
942.
IND£X.
1565
Field switchboards, electrically oon-
troUed. 042.
telegraphs, 1140.
telephones, 1140.
mrireless set-pack, 1145.
Figure of merit of galvanometers,
21.
Filling standard cell, 13.
Fire alann system, U. S. Navy, 1210.
brick, sixes of, 1321.
protection in transformer house,
871.
temperature of, 1340.
Fires caused by lightning, 1270.
due to electrolysis, 850.
Firing guns, navy method of, 1212.
mechanism, electric, 1148.
FLsh ladders, 860.
Fiske range finder, 1211;
Fixtures, U. S. Navy, 1171.
Flame at commutator, 805.
Flame-proof coverings, 030.
Flaming arc lamp, 572.
Flaming-point of carbons, 577.
Flanges, pipe, 1430-1433.
Flat plates. Board of Trade rules,
1333.
boiler, safe pressure on, 1332.
Flash, energy of, 1278.
lightning, data on, 1277.
test of transformer oil, 500.
Fleming's method, meas. A. C.
power by, 71.
modification of Hopkinson*s test,
304.
Flexible dynamo cable, table of, 172.
Flexure of beams, fundamental
formulsB of, 1308.
Flow of steam in pipes, 1416.
of water, estimate of, 860.
in a stream, measurement of,
1471.
in various pipes, 1373.
over weirs, 1473.
through an orifice, 1470.
Fluctuating load diagram, 888.
Hues, boiler, area of, 1320.
Flumes, and ditches, 1468.
Fluoroscopes, use of, 1255.
Fluorspar, spec. ind. cap. of, 36.
Flux density for induction motors,
427.
of force, value of, 7.
for transformer cores, curve of,
446.
in air-gap, 365.
in field magnets, 366.
magnetic, definition of, 4.
Foot, decimals to inches, 1505.
-pound, value of, 12.
valve, 1447.
Forced draught, blowers for, 1344.
Force on conductors in magnetic
field, 108.
de cheval, 3.
definition of, 3.
magnetomotive, definition of, 5.
magnetising, definition of, 4.
unit of, 3.
Forge, electric. Burton, 1274.
Forging by electricity, 1271.
Formulas for transmission lines, 275.
Formula for testing Shallenberger
meter, 1028.
Fortress telegraphs, 1140.
telephones, 1140.
Fort Wayne induction wattmeters,
1005.
wattmeters, testing of, 1082.
Forward lead of brushes, 350.
Foucault currents in armature,
prevention of, 350.
currents, representation of, 386.
Foundation beds, load on, 1202.
concrete, 1202, ^ *
concrete sub-, 1202.
engine, 1202.
on clay, 1200.
on piles, 1201.
on soft earth, 1201.
Foundations, 1200.
and structural materials, 1280.
brick, 1202.
eye beam, 1203.
on gravel, 1200.
on rock, 1200.
stone, 1203.
on sand or gravel, 120O.
Four^ircuit single winding of arma-
tures, 342.
1556
INDEX.
Foor<twrty sdeotive telephone sys-
tems. 1103.
-wire two-phase sswtem, formula
for, 270.
Frame buildinipi, steel, elecirolysia
in. 850.
Frames for switchboards. 908.
Francis* weir formulie, 1474.
Freight elevatore. operating cost of,
1528.
French calorie, 1511.
Frequency converter, def. of, 503.
ssonbol of, 8.
Frequencies, discussion of standard.
522.
of generators. 870.
Friction, 1505.
load in machine shops. 1523.
brush contact, 362.
curve for train, 679.
curves of railway motors. 676.
test for dynamos, 383.
Fuel eoonomisers, 1378.
eoonomisers. Green's, 1378.
value of woods for, 1349.
Fuels, draft neoenary to bum.
1342.
gaseous, 1357.
heat of combustion of, 1347.
kinds and ingredients of, 1346.
liquid, 1356.
total heat of combustion of, 1347.
Fuller cell, description of. 16.
Fundamental principles of dynamos
and motors, 336.
units, definition of, 2.
symbols of, 1.
table of, 6.
Furnace, electric, efficiency of, 1244.
Furnaces, oil, 1357.
Fuse block, ins. of, mens, of, 82.
data, 1275.
wireH, rating of, 1275.
table of, 1275.
Fuses for firing guns, electric,
1134.
for railway circuits, 731.
installation of, 1276.
Fusing effect of current, 217.
puslon. electric, def. of, 1232.
ChftllMi« 1490.
Galvanic cell. 14.
Galvanised Iron
properties of, 190.
iron wire for water rheostats. 31
steel strand wires, 642.
Galvanometer, ballistic, 25.
constant, 23.
D'Arsonval, des. of. 25.
Kelvin tsrpe, 23.
method, differential, res. by. 5ft.
ins. res. of wiring system by.S4
moving coil. des. of, 25.
reflecting, Kelvin, 23.
scale, 24.
shunt boxes, 29.
telescope, 24.
tangent type. 22.
used with potentiometer, 48.
Galvanometers, 21.
figure of merit of, 21.
moving-eoil, 21.
mo\'ing-needle, 21.
resistance of, 60.
Gap, air, mechanical. 363.
distance curves. 234.
Garton lightning arrester. 090.
Gas and electricity compared fcr
cooking. 1260.
and electric rates compared. 1261
engine power plant. 1450.
pumping plant, 1450.
test of. 1450.
engines, 1448.
cUssification of, 1448.
comparative economy of. 14^.
cost of lifting water by using.
1450.
heat energy disposition in. 1450
value of coal gas for. 1450.
light wiring, 295.
passages and flues. 1329.
Gaseous fuels. 1357.
Gases, effect of temp, on fan load.
1346.
specific gravity of, 1612.
Gasner cell. 15.
dry cell, 18.
Gauges, wire, table of. 141.
Gauss, definition of, 4.
^
INDEX.
1557
I, value of, 7.
Own lam pa, 540.
General Eleotrio Company:
A.C. lightning arrester, 087.
A.C. motor characteristics, 713.
A.C. overload relay, 961.
A.C. railway system, 710.
switchhoards, 022. .
oontroUer, 763.
eirouii breaker, 050.
ooDstant current transformera,
464.
induction motorB, 207.
eunent taken by, 207.
looomotives, 740.
mercury arc rectifiers, 480.
multiple unit control, 761.
oil break switch motor, 076.
switch, 070.
prepayment wattmetera, 1010.
railway motors, 720.
ebaracteristio curves of, 686.
reeording meters, 1037.
wattmeters, testing of, 1080.
rubber ins. wires and cables,
tablee of. 164-172.
searchlight, 1181.
surface contact railway, 847.
switchboard panel, 007.
system, electric heating. 1257.
wattmeter constant, 1030.
wires and cables, tables of, 161-
178.
Gieneral symbols, 1.
Generating station, hydro-electric,
section of, 030.
seto, tests on U. S. Navy, 1150.
U.S. Navy. 1153.
Generator circuit protection by
relays, 050.
control pedestal, 040.
current, definition of, 502.
efficiency, U. S. Navy, 1158.
magneto, oonstr. ^, 1078.
panels, Westinghouse three-wire,
026.
D.C., equipment of. 024.
three-phase, 012.
two-phase, 015.
switchboard, U. 8. Navy, 1163.
Generator, three-wire system, 355.
turbo, U. S. Navy spec, for,
1161.
Generators, double current type,
440.
frequencies of, 870.
protection by static interrupter of,
003.
rating of, 505.
regulation of, 870.
speed of, 870.
U. S. Navy, spec, for, 1156.
wiring for, 205.
Geometric units, derived, 2.
table of, 6.
German silver, fusing effect of
current on, 217.
silver, phys. and elec. prop, of,
136.
silver wire, properties of, 202.
res. of, 203.
Gest*s manhole, cut of, 312.
Ghegan repeater, 1042.
Gibbs' process, potassium chlorate
by, 1242.
Gilbert, definition of, 5.
value of, 7.
Glass, specific heat of, 1511.
specific inductive capacity of, 36.
227.
Globes, effect on light of, 582.
Glower of Nemst lamp, 562.
Gold, ph3rs. and elec. prop, of,
136.
plating, 1234.
spec. res. of, 132.
temperature coef . of, 133.
Goldschmidt weld, 778.
Gordon's formuUe for columns,
1300.
Gott's method, testing cap. of
cables by, 326.
Gould storage battery, 1228.
Government printing office, heating
devices in. 1260-1270.
Grades and rise, 617.
effect of, 612.
formula for, 665.
tractive effort on, 657, 661.
Gradient, magnetic, 130.
1558
INDEX.
Gramme arauiture, windingB of, 342.
definition of, 2.
-d^ree C, value of, 12.
Granite, onuhing load on, 1322.
Granular button transmittera, 1074.
Graphic illuminating chart, 587.
recording meters, 1036.
Graphite, production of, 124.5.
Grates, air space m,- 1329.
Grate, space between boiler ami,
1329.
surface per h. p., 1329.
Gravel, foundations on, 1290.
Gravity oell, des. of, 15.
resistance due to, 1224.
Greases, 1497.
Greek letters, 1505.
Green*B fuel economiier, 1379.
Grey cast iron, phys. and elee. prop.
of, 137.
Grinding machines, power required
for. 1521.
Ground connections, 983.
connections for lightning rods,
1279.
detectors, static, installation of,
942.
on arc circuits, meas. of, 81 .
return drop, test of, 799.
Grounded armature, test for, 402.
neutral, circuits with, 984.
Grounding the neutral, 478.
Grouping of cells, 19.
of ducts in manhole, 318.
Grove oell, 14.
Guarantees of transformers, 482.
Guns, coast defense, manipulation of,
1134.
firing. Navy method of, 1212.
motors for operating, 1 191 .
rapid fire, 1149.
Gutta-percha covered wire, jointing
of, 193.
properties of, 231.
spec. ind. cap. of, 36, 227.
Guy wires, 638.
Gsrpsum, spec. ind. cap. of, 36.
Gyration, radius of, 1303.
Gyroetatie action on ship dynamos,
353.
WUklf-Ai^immmm rapeater. 1048.
deflection method, res. of galT. by,
60.
Hall process, aluminum pn>daetk«
by, 1239.
Hand control, A. C. railway syatcn,
710.
•operated oil break swit^, G. E
type, 978.
remote-control . switcbbnafib,
928.
switchboard, 906.
potential control system at G. E.
Co., 710.
Hangers required per spaa for ta»*
gent track, 046.
Hannibal shops, St. Joseph and H.
Ry. motors, 1518.
Haroourt pentane standard, 530.
Hard-drawn copper telegraph wiie,
prop, of, 156.
Hannonies, theory of, 1218.
Head, choice of, 860.
Headway of cars, t^ble of, 658.
speed and number of eais, table of.
660.
Heat, 1509.
absorption curves, 1376.
balance, 1380.
energy from burning gas. 1450.
in printing ptants, eleotrie. I'StA-
1270.
intensity of, 1506.
li^t and power in isolated pIsatK.
cost of. 1285.
cost in residences of. 1287.
mechanical equivalent of.
1511.
of electric are, 581.
radiation in ducts, 214.
run of dynamos, 379.
temperature and intensity of,
1506.
test of induction motors. 396.
of transformer, 480.
transmitted through east iron
plates, 1425.
units, 3. 1258, 1510.
in steam. 1404.
table d, 1510.
INDEX.
1559
energy oonsmnption of
eleotric, 1265.
feed water, 1375.
Heating by oonveetion, 1264.
by nuliation, 1264.
oara by eleotrielty, 770.
devices in laboratoriai, elec., 1270
effect on hysterasis loss in traniH
former, 457.
electric, 1263.
cars, 1266.
daoBifioation of, 1266.
ix&duatrial electric, 1260.
of armatures, 349.
of cables in ducts, 210.
of field coils, 127, 352.
of transformeiB, meas. of, 497.
pipes, condensation in. 1415.
surface of steam boilers, 1328.
of tubes, 1328.
per horse-power in boilera, 1329.
water by electricity, cost of, 1259.
Hefner amyl lamp, 532.
unit, 532.
Hekto-ampere meter, balance wied
as, 44.
Helm angle indicators, U. S. Navy,
1202.
Hemp rope, weight of, 1494.
Henry, definition of, 9, 238.
international, 10.
measurement of, 64.
value of, 8.
Herouit process, aluminum produc-
tion by. 1239.
Herrick testing-board, 805.
Hertzian oscillator, 1057.
Hexane, spec. ind. cap. of, '37.
High efficiency lamps, use of, 589.
High potential circuit arresters, 993.
generators, protection by static
interrupter of, 993.
on A.C. circuits, protection
against, 981*
switches, 967.
tests, U. S. Navy, 1168.
High power transmitters, 1063.
resistances, meas. of, 79.
resMtance for voltmeters, 75.
speed car tests, 727.
High-speed miiway trials, 719.
Hi|^-tension bus bar structure,
935.
conductors, insulation of, 939.
lamps, 570.
lines, aluminum for, 199.
station bus bars, 933.
switches, 967.
transmission, conductors for.
235.
voltage transformers, 938.
wires in power station, 867.
High voltage, break down tests for,
233.
testing set, 461.
tests, 516.
tests of cables, 332.
tmnsmiflsion, 870.
Hissing-point of carbons, 577.
Hoho-Lagrange system, 1274.
Hoist, ammunition, electric, 1147.
Hoists for ammunition, U. S. Navy,
1191.
Holden hysteresis meter, 102-104.
Hollow shafts, 1485.
Holtier-Oabot telephone system,
U. S. Navy, 1208.
Hook switch, design of, 1075.
Hopkinson*s test of two similar D.C.
dynamos, 393.
Horiaontal return tubular boilera,
1327.
plane illumination, 586.
Horn tsrpe lightning arresters. 995.
Horse-power, definition of, 3.
formulsD for machine tool re-
quirements, 1515.
of lianila ropes, 1491.
of motors, meas. of, 395.
of railway motors, 731.
of nmning stream, 1462.
of steam boilers. 1327.
of steam engines, 1440.
of street railway motors, 661.
of traction, 653.
of water, tables of, 1475.
required for automobiles, 1224.
second, value of, 12.
used in electric welding, 1271.
used in factories, 1517.
1560
INDEX.
Hotel telephone systenui, 1068.
Hot-filament deteotots, 1068.
Houn of burning lights, 611.
House eirouite, res. of, 61.
telephone systems, 1088.
tTBnaformera, oapadty of, 458.
wire, weather-procrf, table of, 160.
wiring, 279, 293.
Humphreys' lighting tables, 607.
Hydraulic head, ohoioe of, 869.
plants, ooostr. of, 868.
turbines, regulation of, 614.
Hydro-eleotrio plant, section of, 930.
switchboard for, plan of, 931.
transformer cell, plan of, 931.
Hydro-electrothermio system, 1274.
Hydrogen as depolariier. use of, 879.
spec. ind. cap. of, 35.
Hysteresis curves for tranrformer
cores, 453.
factors, table of. 100.
in armature core, 341.
index, 99.
loss factors, table of. 00.
loss, formula for, 98.
in transformer core, table of, 457.
in transformers, law for. 445.
tests, 885.
meter, Q. E. type. 102-104.
tester. Ewing type, 102.
testing by step>by-step method.
101.
testing by wattmeter method, 102.
Hysteretic constonts, table of, 99.
lA f ▲ wire, properties of, 204.
IllumiDants, rating of. 540.
Illuminating chart, 588.
engineering, 584.
lamps for switchboards, 909.
values, data on, 592.
Illumination, efficiency of, 584.
formulae for. 584, 587.
for reading. 602.
for various purposes, 580.
intensity of, laws of, 528.
table of, 586.
of interiors, 596.
Impedance coils, use of, 429, 1117.
definition of. 259.
Impedance ooila^ f oniuila fair, 1221.
in alternators, 405.
in A.C. coils, 127.
of steel rails to A.C. eorreat. 796^
of transformer, mens, of, 487.
Impedance ratio, def . of. 514.
symbol of, 8.
Impressed EJf .F. ounree, 1218.
239.
Improvement in transffonnen, 4M.
Impulse currents, gemaiator for.
1103.
water wheel, 1477.
Impulsive rush diaehai^BBs, 127&
Impurities in electrolyte, S77.
Inoandesoeot lamps as
538.
burning out of, 805.
cost of, 556.
efficiency of, 540.
light by, 601.
luminosity of, 548.
navy spec, for, 1171.
navy standard, 1176.
proper use of. 544.
rating of. 526.
renewals of, 556.
uses of, 555.
Incandeeoent station
airester, 086.
Inch, miner's, 1473.
Inohes to decimals of a foot, 1506.
to millimeters, 1504.
Inclined planes, strains in rope on,
1494.
Inclosed fuses. 1276.
Incrustation, causes of. in boikgi^
1362.
ineans for preventing. 1362.
Index, hysteresis, 99.
notation. 2.
Indicators, order, U. 8. Navy, 1202.
Induced E.M.F. in tranrfonncn.
equation for. 446.
draught, fans for, 1345.
Inductance and capacity, neutrali-
sation of, 292.
choking effect of, 1079.
definition of. 9
iightnieg
INDEX.
1561
jndluctanoe and capacity in A.C.
circuit, effect of, 1216.
mutual, meas. of, 67.
of A.C. circuits, 239. 259.
[xsducUon ooil. oonstr. of, 1074.
ooil, design of, 1074.
for X-rays, use of, 1252.
ooef . of, meas. of. 65.
deotroioagnetio, 64.
law of. 64.
maohines, losses In, meas. of, 511.
magnetic, definition of, 4.
meters, design of, 1003.
3jaduotion motor, current taken by.
297.
flux densities for. 427.
methods of starting, 918.
panels, equipment of, 918.
polyphase type. 422.
power del'd to. 280.
regulation of. 383, 513.
rotor slots for, 427.
slots in field frame of, 426.
speed of, 424.
transf ormere for. 296.
test of, 397.
wiring for. 296.
Induction potential regulator, 469.
503.
tel^raph, field, 1140.
transposition to eliminate. 285.
type furnace, 1244.
wattmeters. Westinghouse. 999.
1003.
wattmeters, Thomson polyphase,
1005.
Inductive capacity, spec., def. of,
38.
capacity of gases, values of, 35.
of liquids, table of, 37.
cf solids, table of, 36, 37.
circuits, wattmeters on, 1000.
drop in trolley, 797.
effect of alternating currents, 236.
load, def. of. 504.
regulation of traniformer for.
492.
loads, testing meters on. 1018.
reactance, formula for, 239.
In ohms per 1000 feet, 242.
Inductive reaetanoe in solid iron
wire, table of, 248.
in three-phase line, 245.
representation of, 250.
Inductor type synchroscope, 417.
Industrial electxio heating, 1269.
Inertia, moment of, 1302.
of rotating parts of train, 683.
Ingredients of rails, table of. 780.
Injectors, deUveries by live steam,
1371.
exhaust, 1372.
lifting cold water by. 1372.
hot water by, 1372.
live steam, 1370.
performance of, 1371.
■ vs. pumps for boiler feeding,
1372.
Installation of battery plants, 897.
ci oar moton, 745.
of fuses, 1276.
of polyphase meters, 1023.
of storage batteries, 885.
Instantaneous relays, 956.
value of E.M.F. of A.C. current,
404.
Instrument posts, 941.
scales, figuring, 946.
Instruments, electrical measuring,
21.
for switchboard, 940, 945.
testing, description of, 13.
Insulated cables, varnished cambric,
triple conductor. 185.
cables, varnished cambric, tables
of. 179-183.
copper wires and cables, table of.
160.
wires and cables, rubber oov., tables
of. 164-172.
carrying capacity of. 209.
locating faults in. Warren's
method of. 330.
Insulating cable ends for tests, 322.
cable joints, 191.
ground near power station, 862.
joints in mains. 861.
materials, dielectric strength of,
228.
puncturing voltages for. 228.
1562
INDEX.
Insulatkm aoroos fuse blook« meas.
of. 82.
distanoes oo awitohboards, 912.
of armature core, 341.
of dynamos, meas. of« 86.
of high^tenaioii oables, 930.
of tranflformer, 447.
leBhtaaoe batw. oonduotore. N. C.
85.
by Io08 of eharge method, 322.
meas. of, 514.
of are Ug^t drouito, 81.
of oables, 321.
of drouits, meas. of, 80, 85.
of dynamos, 86.
of motors, 87.
of railway lines, 783.
of rubber, 231.
of tdei^one cables, 1084.
U. S. NaxT standard. 1168.
of wiring system, 82.
test of oables, 832.
of dynamos, 381.
of rubber. 230.
of transformers, 483.
Insulators for third rail, 831.
Metropolitan street railway, 840.
on poles, arrangement of, 291 .
Integrating meters, action of, 997.
meters, Westinghouse, D.C., 998.
photometer, 539.
wattmeters, data for, 1016.
induction type, 999.
tests of, 1013.
Westinghouse, 1004.
Intensity of brilHsney, 599.
of current, symbol of. 8.
of illumination, laws of, 528.
table of, 586.
of light, 530.
of magnetic field, 4.
force, def . of, 108.
of magnetisation, 4.
value of, 7.
of searohlii^ts, 1125.
Interaxial distances between A.C.
oonduotofB, 240.
Interborough rail, 830.
Interoommunicating telephone sys-
tems. 1088. 1114.
Inter-connected star
of three-phase
477.
Interior ilIuniinatioii« 596.
wiring, oarryiog cap. ai coDtLlK,
209.
Interlock switches for railway <■•■
trol, 768.
Intermediate diatribirtiac
1104.
Internal characteristic of
dsmamo, 339.
resistance of batteries, iiifai cL,
87.
of cdb. 20.
of storage batt«rieB. S&.
International ampere, def. of, 9.
ampere, specification for delerm,
10.
coulomb, def. of, 0.
electrical units, 9.
farad, def. <tf. 9.
standard, 38.
henry, value of, 10.
joule, value of, 10.
ohm, construeticm of, 90.
def. of, 9.
value of, 131.
volt, definition of, 5, 0.
determ. of, 10.
watt, value of, 10.
Interpolar edges, design of, 363.
Interrupters, Wdindt, 1254.
for X-rays, use of, 1253.
Interurban booster eafeuklipa.
812.
car tests, 722, 725.
Intrinsic bri^tness of soarees of
light, 529.
Inverse time limit rdasrn, 957.
Inverted converter, def. of, 436-
Inward flow turbines, 1476.
Iron agdng testis, curves of, 453.
and steel, agnng of, 455.
eleo. welding of, 1271.
magnetic fatigue of. 455.
permeability curves of. 90.
wire, constants of, 199.
fusing effect of current on. 217.
in deotrolyte, test for, 877.
INDEX.
1563
loflB oonres of Weetinghouae
motoni, 674.
determinations, 107.
In transfonner, table of, 482.
in transformer cores. 453.
in transformer, Sumpner's
method, 496.
etio properties of, 89.
pcmneability of, 89.
meas. of, 94.
X>h9^. and elec. prop, of, 137.
pieces of, attraction between. 111.
K>ipe, eleo. welding of, 1272.
plating, 1234. •
poles, 633.
production of, 1247.
0peo. res. of, 132.
stacks, guyed, cost of, 1344.
telegraph wire, galv., properties
of, 199.
tcrmperature coef. of, 133.
U. S. standard gauge, weights of,
1299.
weight of, 1294.
flat per foot, 1295.
plate, 1298.
square and round, 1297.
wire for water rheostats, 34.
inductive reactance in, table of,
248.
self induction in, 240.
self induction in, table of, 248
skin effect factor for, 238.
use in telephony of, 1082.
Irons, electric, ooet of operating,
1263.
soldering and branding, elec., 1270.
Isolated electric plants, economy of,
1283
plant, coal consumed by. 1286.
vs. central station, 1286.
Isolation of conductors on switch-
boards, 929, 936.
Itemised cost of conduit, tableof . 316.
JTacks for ammetM* oonnections,922.
telephone, 1089.
Jamison rule for ins. res., 85.
Jigger, use of, 1065.
Joint effect of electrolysis, 853.
Jointing gutta-jpercha covered wire,
193.
Joints, Dossert cable, 191.
in cables, testing of, 323.
in mains, insulating, 861.
in paper insulated cables, 191.
in rubber ins. cables, 190.
in Waring cables, 191.
per mile of track, 618.
rail, tests of, 801.
insulating cable, 191.
Joly's photometer, 536.
Joule, definition of, 3.
value of, 5, 8.
Joule's equivalmt, 4.
Jump distanoe curve, 234.
Jumping*point of oarbons, 677.
Junction boxes, U. B. Navy spec,
for, 1171.
KappV efficiency test of two dyna-
mos, 387.
potential regulatore, 468.
Kempe rule for ins. res., 85.
Kelvin balance, diagram of, 44.
electric balance, 43.
electrostatic voltmeter, 40.
galvanometer, 23.
Kelvin's double bridge, 59.
law, 261, 787.
applied to booster distribution,
810.
multicellular voltmeter, cap. test
with, 326.
Kerosene for boilers, 1364.
Kilowatt curve for railway motors,
669.
Kilowatts of energy in three-phase
cables, 216.
on grades, 657.
Kinetic energy, 3.
King carbide furnace, 1245.
KirchofTs laws, 55.
Knee of saturation curve, 401.
Krupp's wire, properties of, 202, 206.
Kryptol method, electric heating,
1257.
Isabel rating of gem lamps, 549.
Laboratories, electric heat in, 1270.
1664
INDEX.
Lagsing current, effect of, 439.
Lake electric railway, high-speed
triab on, 719.
Lamination of cores, reason for, 99.
Laminations for transformer core,
445.
Lamp indication for oil circuit
brealcer, 975.
renewals, 547.
signals, telephone, 1098.
Lamps, candle-power of, drop in,
544.
current taken by, table of, 542.
efficiency of. 525.
life of. 544.
material required for instal. of,
1531.
Navy spec, for, 1171.
U. S. Navy standard, table of,
1176.
Lande cell, 14.
Lanterns, diving, 1179.
Lap-connected armature windings,
345.
Lateral, def. of, 302.
effect of electrolsrsis, 853.
Lathes, power required for, 1516.
Law cell, 15.
of Brown & Bharpe wire gauge,
142.
of induction, 64.
of plunger electromagnet, 127.
of traction, 110.
MaxwelPs, 94.
Laws, Kirohoff*s, 55.
of circuits, elementary, 55.
Laundry irons, electric, cost of
operating, 1263.
Layers of cot ton -covered wires,
space occupied by, tables of,
121-126.
Laying out dynamos, prcHsedure in,
370.
Lay-overa at end of run, 676.
Lead burning, 885.
covered cables, carrying capacity
of, 213.
covered cables, tables of, 174-
178.
covering of cable joints, 191.
Ijeadburnins,j
on, 217.
of brushes. 350.
peroxide, use in b»tteriei d- ^
phys. and dec. prop. o£. 137.
plates, joinins of, S85.
sheathed telephone cahhi. 1&
telegraph cables, 189.
sheath of cable, Boea at poiMMk
293.
spec. res. of, 132«
sulphate, use oC, 873.
temperature ooef . of, 133.
Leading current, production of, €1
Leads for transfoiiners. 499.
Leakage current on railway line 7S.
coefficients, magnetic, 376.
drop in transformera, noeas. ci
497.
of magnetic lines in dynamoa, 3S^
Least exciting ourrent of nj*'
chronoua motora, 400.
Ledanch^ cell, des. of, 16.
Leeds A Northnip bridge. 32.
Legal ohm, value of, 131.
Lemon oil, spec. ind. cap. of, 37.
Length, measures of. 1490.
of magnet coils, oorreetloas for,
tobies of, 117-120.
of magnet cores, 365.
of sparks, curves of. 049.
Leonard's system of electric pnt-
pulsion, 354.
of motor control, 354.
Le Roy method, eleetrie heatiac;
1257.
Letters, Greek, 1505.
Lever switches, 963.
Life of carbons, 577.
of lamps, 544.
tests. Navy spec, for lamp. 1172.
Liftinft-power of electromagnets, 110.
Light and power cables, 320.
control from two or more pointy
294.
out off by globes, 582.
date on, 528.
distribution of. 599.
heat and power, cost in rssldenm
of. 1287.
INDEX.
1565
lit, heat and power in isolated
plants, ooet of. 1285.
tandard of. 530.
mits of. 530.
chtins ca», G. E. railway system,
851.
sarcuits, res. of, meas. of. 80.
tines, transposition of, 285.
methods, comparative values of,
594.
of street cars, 806.
plant, batteries for residential,
898.
schedule for London. 611.
schedules. 603.
service, navy, 1153.
system, U. S. Navy. 1171.
ightning arresters, arc station. 085.
direct current. 984.
function of, 980.
Garton, 900.
General Electric A.C.. 987.
high iwtential circuit. 993.
horn type, 995.
incandescent station, 986.
in central stations, 983.
in power station. 867.
inspection of, 984.
insulation of, 984.
low equivalent, 994.
magnetic blow-out, 987.
multiplex three-phase, 988.
non-arcing D.C., 984.
metal double pole, 989
railway non-ardng, 985.
s.jv.L«t, 990.
spark gaps of, 991.
Stanley, 990.
unit, 990.
use of, 1087.
Wurts type, 984.
lightning flash, data on, 1277.
protection, 980.
Lightning rods, history of, 1277.
installation of. 1278.
points of. 1281.
tests of. 1282.
Lime mortar, 1293.
Limestones, crushing load of, 1322. I
Limitation of voltages. 866.
Limit of sag for aluminum wire, 225.
Limits of telephonic transmission,
1107.
Lincoln synchroniser, 416.
Lineal measures, metrical equiva-
lents of, 1500.
Linear space ooeupied by d.e. oov.
wire, table of, 123-126.
s.o. oov. wire, table of. 121-123.
Line capacity, effect of, 264.
discharger of 8.K.C. arrester, 991.
drops, 1000.
equipment, depredation of, 770.
formulse, transmission, 275.
material per mile of trolley, 643.
power loss in, 261.
pressure, adv. of high, 260.
relay for railway control. 769.
switch for railway control, 767.
wire, weather-proof, table of, 160.
Link shoe for third rail, 832:
Liquid fuels, 1356.
rheostats. 33.
Liquids, measures of, 1500.
measures of, metrical equivalents
of, 1502.
specific gravity of, 1512.
ind. cap. of, table of, 37.
res. of, 133.
Load curve, 887.
diagram, fluctuating. 888.
factor, def . of, 504.
of railway system, 785.
factors, cost of power at various,
868.
hauled by motor oar, 655.
losses, meas. of, 509.
on foundation beds, permissible,
1292.
peak, batteries to carry. 886.
' power factors. 279.
steel beams, safe, 1310.
test of motors, 395.
Loading gear for guns, 1191.
telephone lines, 1107.
Local action in storage batteries, 878.
Locating breaks in cables by cap.
test, 327.
crosses in cables, Ayrton method,
327.
1566
INDEX.
Loeating faults in cables, loop
method, 328.
in underground cables, 331.
Location of tranafonnen, 489.
Locomotives, electric, dl4.
electric, table of, 739.
tnMstive coefficient of, 662.
Loft building plant, economy of,
1285.
London, lii^ting schedule for. 611.
Long distance transmission, data on,
866.
transformers for, 474.
Loop method, locating faults in
cables by. 328.
liord Kelvin's composite balance, 43.
multicellular voltmeter, cap. test
with, 326.
Lord Rayleigh's method, E.M.F. of
batteries, 62.
Loss factors, hsrsteresis, table of, 99.
in line, power, 261.
of active material in battery platen,
881.
of capacity of storage batteries,
881.
of charge method, ins. res. by 322.
of storage batteries, 884.
oi head due to bends, water, 1374.
of potential method, meas. cap. by,
64.
of power in cable sheath, 293.
of voltage in storage batteries, 882.
I>osso at brush faces, 362.
core, 98.
electrical method of supplying,
389.
in armature, formula for, 358.
in machines, meas. of, 509.
in transformers, 445.
comparative, 455.
curves of, 453.
Lowell mill power, table of, 1464.
Low^uivalent lightning arrester,
994.
resistance detector. 1065.
meas. of. 59.
tension lamps, 569.
voltage A.C. relay. 962.
D.C. relay. 961.
Lubricants, best for diff. pui iiftw,
1408.
Lubrication, 1497.
of engines, 1413.
of motors, oa^'y spec. for. 118S
Lumen, def . of, 592.
Luminosity of inc. lamps, 548.
Luminous flux, 529.
Lummer-Brodhun photometer, 9S
Lumsden's method. E.M.F. of bsra-
ries, 62.
BEachlaei shops, friction load is.
1523.
lighting of. 597.
men employed in, 1523.
power to run, 1518.
toob, power to drive, 1515.
Magazine light boxes, U.S. navy.l 1?L
Magnesium, phys. and elec. prop, d, \
137. I
Magnet coils, correcting length of,
table of, 117-120.
coils, general data on, 352.
heating of, 127.
cores, design of, 365.
poles, determination of nunxberflC.
355.
windines. field, 360.
wire, res. of, table of, 112.
Magnetic blow-out lightningairester,
987.
circuit in dynamoe, tmianfing oS.
349.
of transformer core, eqivtioB
for, 446.
principle of, 109.
density of transformer ocnea, 447.
of field magnet cores, 365.
of armature oores, 357.
of armature teeth. 367.
of pole faces, oalc. of. 356.
detectors, 1067. !
distribution, curve of, 340.
fatigue of iron and sted, 455.
flux, d^nition of, 4.
formula for, 109.
field, intensity of, 4.
force, intensity of, 108.
gradient, 130.
INDEX.
1667
letio induction, definition of, 4.
^alue of, 7.
akage ooeffioienta, 376.
in dynamos, 305.
Loment, 4, 7.
ibility, definition of, 5.
];>ropertie6 of iron, 89.
z-«8i8tanoe, definition of, 5.
specific, 5.
SQiiare method, determ. maffn.
values by, 93.
susceptibility, definition of, 5.
units, definition of, 4.
symbols of, 1.
table of, 7.
values, deteiminstion of, 91.
BAa^netism, residual, def. of, 108.
"BAaenetite arc lamp, 570.
Bftasnetization, intensity of, 4.
« of electromagnets, table of, 111.
curve of dynamos, 336.
curves of D.C. motor, 353.
Bilasnetising force, definition of, 4.
value of, 7.
Magneto-generator, (y>nstr. of, 1078.
Magnetometer method, determ.
magn. values by, 91.
Magneto-motive force, def. of, 5, 108.
value of, 7.
Magneto potential regulators, def. of,
503.
Magneto transmitters, 1071.
Magnets, excitation of field, 365.
field, design of, 364.
Main distributing frames, 1104.
Mains, insulating joints in, 861.
Maintenance of Nemst lamps, 564.
Mance method, res. of batteries by ,61 .
Manganese, eflfect on steel of, 825.
steel, phys. and elec. prop, of, 137.
Manganin wire, properties of, 202,
204.
Manhattan rail, 830.
Manhole oonstr., cuts of, 309.
constr. for shallow trenches, 310.
improved forms of, 318.
of Niagara Falls Power Co.,
319.
objectionable types of, 318.
cost of, 5' X 6' X 7'. 316.
Manhole covers, outs of, 313-^15.
def. of, 301.
estimating cost <rf, 317.
of conduit Metropolitan Railway,
838.
Manholes, brick, cost of, 303.
concrete, cost of, 303.
cost of, table of. 302.
sises of, 302.
Manila rope, data on, 1492.
Manipulation of coast defense guns,
1134.
Marble, crushing load, 1322.
for switchboards, 907.
Market wire gauge, use of, 201.
Mascart electrometer, 39.
Masonry, 1321.
Master controller, multiple unit
system, 764.
Material per mile of trolley line, 643.
required for one mile of railway,
628.
Materials, strength of, 1301.
Mats burglar alarm, wiring of, 295.
Matthiessen's copper formula, 133.
standard of conductivity, 132.
Maximum current, A. C. windings,
127.
output of induction motors, 398.
value of E.M.F. of A.C. current,
404.
Maxwell, definition of, 4.
law of traction, 94.
value of, 7.
Mean current, A.C. windings, 127.
effective pressure, table of, 1442.
hemispherical candle-power, def.
of. 529.
horizontal intensity, 529.
length per turn of coil, table of,
114-116.
spherical candle-power, def .of , 529.
spherical candle-power of arc
lamps, 580.
Measure, apothecaries*, 1500.
avoirdupois, 1500.
of capacity, 1499.
of length. 1499.
of liquids, l.'iOO.
of surface, 1499.
1568
INDEX.
Measure of wai^ta, 1500.
troy, 1500.
Measurement of altenutting ouirents,
26-28.
of capacity, 63.
of E.M.F.. 62.
of ins. res. of cables, 321.
of low resistance, 59.
of mutual inductance, 67.
of resistance, 56.
of standard ampere, 10.
of three-phase power, 72.
Measures, metrical equivalents,
1500.
Measuring instruments, electrical,
21.
power in six-phase oireuits, 477.
Mechanical and electrical units,
table of, 1258.
air-gap, 363.
equivalent of heat, 1511.
interrupters, 1253.
properties of rubber, 229.
stoking, 1350.
ssmibols, 1.
units, derived, 2.
table of, 6.
Mega-eiig, value of, 12.
Megohm, definition of, 6.
Melting point of copper. 143.
point of substances, 1532.
railway bonds, 773.
Merourous sulphate for standard
cell, 11, 13.
Mercury and water columns, pres-
sure of, 1463.
are rectifiers, 480.
for battery charging, 482.
auto-coherers, 1066.
for standard cell, 11.
phys. and elec. prop, of, 138.
spec. res. of, 132.
temperature ooef . of, 133.
vapor lamps, 558.
Merrill on water rheostats, 33.
Mershon's method, meas. of wave
form by, 49.
Metalized carbon lamps, 549.
Metal joints in cables, 190.
pipes, effect oi current on, 852.
MetaUie aro lamp, 572.
cirouits in telephony, lOSI.
sheath, capacity erf two wire§
250.
sodium, production of, 1241.
Metals, phys. and elec. prop,
table of, 134-140.
temperature ooef. of, 133.
by fusion of. 1349.
Meter bearings, 1009.
commutator type, D.C^ 997.
Duncan, 998.
hysteresis, G. E. type, 102-104.
Shallenbeiger. 1028.
testing formula, 1027.
Westinghouse, integrating,. 998. *
Wright discount. 1008.
Meters, action of, 1039. i
constants of, 1029. i
direct current, testing of. 1020. .
electric, accuracy of, 997.
graphic recording. 1036. ,
integrating, action of, 997.
polyphase, service conneetioas of,
1023.
testing of. 1020.
remedy for electrolysis in, 861.
speeds of, 1029.
switchboard, list of, 945.
to feet or inches. 1503.
Methods of lighting, efficiency of,
594.
Metrical measures, 1500 to 1504.
Metropolitan conduit railway ayt-
tem, 837.
street railway system, 836.
Mho, value of, 8.
Mica for oommutatois, 351.
puncturing voltage of. 234.
spec. ind. cap. of. 36, 227. ,
Micanite. spec. ind. cap. of, 227.
Micro-Farad, definition of, 5, 38.
Micron, 1500.
Miles per hour in feet per minute,
660.
Millihenrys of non-OMgnetie wire,
241.
Milliken repeater, 1041.
Milling machines, power required by,
1522.
"^
N
INDEX.
1569
^voltmeter, meas. oi oond. with,
87.
:k«thod, meas. of current by, 78.
ci.eas. Binall res. with, 79.
I power, 1462.
a to oentimetere, 1503. .
leral oils, 1497.
aer's inch, 1473.
intter H.P. table. 1475.
aes, electric land, 1137.
Dimnrn siae of higfa>tenaion oon-
ductora, 235.
nnor galvanometer, 23.
tpeo. ind. cap. of, 36.
Boellaneoas tables, 1499.
»dulus of elasticity, 1302, 1312.
off elastic resilienoe, 1312.
of rupture of woods, 1317.
>hawk type locomotive, 740.
oisture in steam, 1394.
aleoular magnetic friction, meas.
of, 508.
oment, magnetic, 4.
of inertia, 1302.
compound shapes of, 1303.
table of. 1304.
of resistance, table of, 1304.
of rupture of beams, 1309.
ci stress of beam, max., 1309.
Omentum, definition of, 3.
[onolithio conduits, des. of, 301.
[oonlight schedules, 603.
[oore tube, efficiency of, 666.
vacuum tube light, 565.
lortar, cement, 1293.
lime, 1293.
[ortars, 1293.
lorse code, 1052.
system, description of, 1040.
lotive powers, 864.
lotor brushes, backward lead of,
353.
capacity curves, railway, 676.
car batteries, electrolyte for, 877.
dimensions of, table of, 732.
horse-power of, 653.
characteristics, 685.
combinations, 760.
control. Ward Leonard's system,
354.
Motor converter, def . of, 503 .
definition of, 502.
equipments, weights of A.C., 719.
field magnets, flux in, 367.
-generator, definition of, 502.
•generators, 434.
-generator turret turning system,
1189.
men, personal factor of, 724.
operated oil break switch, G. E
type, 976.
panel, D.C., equipment of. 928.
pafaeis, induction, equip, of, 918.
three-phase synchronous, equip,
of, 919.
regulation, test for. 382.
retraction, gun operation, 1134.
tests.' 394.
traversing, gun operation, 1134.
work, variable speed, ssrstem for,
354.
Motors and dynamos, tests of, 378.
automobile, 1227.
boat crane, Navy spec, for, 1194.
circuit breakers for, capacity of,
955.
controlling panels for Navy .tpec.
for, 1185.
counter E.M.F. in armatures of,
353.
efficiency curve of, 370.
of. Navy spec. for. 1185.
of railway, 803.
tests of. 395.
electric railway. 614.
Q.E. railway system, 851.
induction, starting of, 918.
ins. res. of, meas. of. 87.
lubrication of. Navy spec, for,
- 1185.
magnetisation curve of D.C., 353.
Navy spec, for, 1183.
railway windings of armatures
for, 348.
rating of railway. 523.
rise of temperature in. 378.
street railway, rating of, 661, 673.
S3mchronous, tests of, 399.
used as condensers. 292.
temp, rise of. Navy spec, for, 1 184.
1570
INDEX.
Motora, tost of street car. 392.
torque of armatures of, 353.
used to drive machine tools, 1518.
ventilation fan. Navy spec, for,
1196.
Moving body on air resistance, effect
of, 659.
-coil galvanometers, 21.
des. of, 25.
-needle galvanometers, 21.
Multicellular voltm'tter, cap. test
with, 326.
Multi-circuit single winding of
armature, 342.
-contact transmitters, 1072.
-phase transformers vs. single-
phase, 871.
-polar machines, armature ' wind-
ings for, 345.
-speed motors, def. of, 504.
Multiple circuits, current in, 55.
circuits, res. of, 55.
conduits, adv. of, 301.
connection of alternators, 420.
of batteries, 19.
control, A.C. railway system,
710.
unit switch system, 766.
duct conduit, oonstr. of, 301.
switchboards, 1090.
telephone system, adv. of. 1094.
unit control. G.E. type, 712. 761.
Multiplex armature windings, 347.
telephony, 1106.
throe-phase lightning arrester,
988.
Multiplier, Y-box, Weston, 73.
Multiplying power of shunt, 29.
Murray's method, locating faults in
cables by, 328. •
Mutual inductance, def. of, 236.
inductance, meas. of, 67.
secohmmeter method, 69.
induction, transposition to elimi-
nate, 285.
neutralization of capacity and
inductance, 292.
MiatloiiAl coast defense board,
recomm. of, 1123.
National Eaeetrical Ooda. standi
conductors, table of, 162.
Electrical OoDtraetorB* Asm
symbols adopted by, 299.
Natural draft tranafocmerB, 448.
Navy electric fuse^ 1137.
generating sets, 1153.
special lamps, 1173.
specifications, 1153.
standard wires, table of, 174.
telephone systems, 1206.
U. S., electricity in, 1153.
wiring spedficationa, 1167.
Neatsfoot oil, spec. ind. cap. of. ?
Needle point spark gap curve, 23l
Negative booster, 790.
Nemst lamps, descr. of, 562.
rating of, 540.
Ness telephone switch, 11 IS.
Neutral, grounding of, 478.
unstable, 479.
Neutralisation of capacity v
inductance, 292.
Newburgh telephone ssrstem. 1103
New York central looomotivea, 74
Central third rail, 834.
City, electrolysis in lower, 858.
lighting table for. 604.
Niagara-Buffalo Line, arran«eeni%^
of, 290.
Falls Power Co., manhole const
of, 319.
.\ickel, phys. and elec. prop, oi
138.
plating, 1234.
spec. res. of, 132.
steel, phys. and elec. prop, d
138.
tonperature, ooef. of, 133.
Nickelioe. phys. and dec. prop, of
138.
Night sights, electric, 1148.
Nitrates in dectrolyte. test for. 878
Nitric acid, spec. res. of, 133.
Nitrous oxide, spec. ind. cap. of, 35
Noark fuses, 1276.
Non-arcing lightning arresters, 984
metal lightning arrester, 989.
railway lightning arrester. 985.
Non-inductive load, def. of, 504.
INDEX.
1671
901
inductive load, regulation of
<ra.nsformer for, 492.
asnotic wires, ind. reactance of,
^ t&ble of. 242.
tL"
.A^Knetic wires, self-induction in,
239.
.. 9versible booster, use of, 893.
.,* le -wrave, def. of, 506.
:hrup instrument, des. of, 26,
*" 28.
■T.ctliod, conductivity by, 60.
'~ meas. ins. res. by, 82.
^ [ation. A.I.E.E.. 523.
" '>inniittee on, table by, 6.
^ idex, 2.
fted in dynamo and motor
' ' section, 334.
Id, spec. ind. cap. of, 37.
wylene, spec. ind. cap. of, 37.
rated, definition of, 5.
' alue of, 7.
ice building plant, economy of,
' 1285.
am, definition of, 5.
international, construction of, ?0.
' def. of, 9.
j>cr mil-foot, def. of, 131.
"value of, 7, 8.
hmic resistance of storage cell, 883.
hmmeter, direct reading, 57.
Sage type, 58.
•hm's law, 55.
4iins, value of various standard,
131.
>i1 and coal, comparative costs of,
1358.
' break switch. General Electric
motor operated, 976.
circuit breaker, controller. 975.
breakers, arrangement of. 935.
breakers, Westinghouse, 969.
-cooled constant current trans-
formers, 465.
transformers, 448.
flash test of transformer, 500.
for lubrications, 1497.
for transformers, specifications
for, 600.
in transformers, use of, 448.
Oil switch. General Electric, 979.
switches, arrangement of, 933.
hand operated. electrically
tripped, 979.
operation of, 967.
specifioations for, 947.
use of, 912.
weight per gallon of, 1497.
Olive oil, spec. ind. cap. of, 37,
227.
Open cars, weight of, 736.
circuit A.C. armature winding,
410.
circuit cells, 15.
Open circuit in armature, test for,
402.
wire circuits, 1082.
Operating cost of gas and elec.
cooking. 1260.
cost of lamps, 554.
elec. oooking utensils, cost of,
1261.
elec. heaters, cost of, 1265.
Opposition method of testing trans-
' formers, 496.
Order indicators, U. S. Navy, 1202.
Oscillating current, definition of,
502.
Oscillations, electrical, 1055.
in ether, 1278.
undamped, 1068.
Oscillator, dumb-bell type,1066.
Oscillograph, Blondel type, 50.
Outer rail, elevation of, 617.
Outflow of steam, 1416.
into atmosphere, 1416.
Output of dynamos, formula for,
356.
of motors, test of, 395.
Outward flow turbines, 1476.
Over-compounded dynamo, charac-
teristic of, 340.
Overhead lines, drop in, 798.
lines, transposition of, 285.
railway conducting system, 785.
trolley construction, cost of,
629.
wires, capacity of, 250.
Overland wires, breaks in, location
of, 327.
1672
INDEX.
Overioad A.C. roky, 962.
capaoitieB, 521.
capacity, test of, 381.
eireuit breakers, 899, 950.
guarantees for machines. 947.
relay, Westinghouse A.C., 962.
Overshot water wheels, 1476.
Overspeeding oi rotaries, preven-
tion of, 961.
Over-voltage relay, Westinghou-se,
D.C., 962.
Oaokerite, spec. ind. cap. of, 37, 227.
of transmittem, 1074.
Painting. 1498.
exposure tests, 1498.
Palladium, phys. and elec. prop, of,
138.
Pan-cake form of winding, 410.
Panel switchboards, design of, 906.
Panels, motor controlling, navy spec,
for, 1185.
rotary converters, equipment of,
924.
Paper insulated cables, carrying
capacity of, 208.
cables, joints in, 191.
tables of. 174-178.
telephone cables, 188.
Paper, spec. ind. cap. of, 36, 227.
Parabolic curves in wire spans,
charts of, 218.
Paraffin, spec. ind. cap. of, 36, 227.
Parallel, oondensera in, 63, 324.
D.C. distribution, sise q£ con-
ductors for, 284.
distribution, 277.
-flow turbines, 1476.
running of alternators, 419.
Para rubber, electrical properties of,
229.
Parson's steam turbine, 1453.
Party lines, demand for, 1102.
telephone lines, 1108.
ParvilU method, electric heating,
1257.
Passenger elevators, operating cost
of, 1528.
Paflt-ed electrode battery, advan-
tages of, 880.
Pasted plates of atorace eeBs, 880.
Patent-nickel wire, propcrtaa &C
202.
Pavement, cost of. 619.
Paving, cost of. 305. 619.
depreciation of, 770.
Peak disoharee of batteries, 8S8L
of load, batteries to carry. 881
Peggendorff cell, 14.
Penstocks, constr. of, 869.
Pentane standard lamp, 530.
Percentage conductivity. 132.
drop, discussion of. 262.
Performance diasram, train, tH
667.
Permanent magnetism, def . of. 1<&
magnet voltmeters. 74. ]
Permeability curve of are dynaoB. ^
338.
curves of iron and steel. 90.
of iron and steel, 89.
value of, 7.
Permeameter, Drysdaie's, use of. 9'-
Thompson's use of. 93-96.
Personal factor of motormeo. TlSt
Petroleum, chemical oompositioo d
1356.
I
furnaces. 1357. i
oil. spec. ind. cap. of, 37, 237.
oils, chemical oomposition d
1357.
Phase-displacing apparatus, kms .
in. meas.of. 512.
Philadelphia Inspection Roles for
boilere. 1332.
Phillip's code. 1052.
Phoenix rule for ins. res.. 86.
Phonograph in t^epbony. use of. ,
1096.
Phosphor-bronse, ph3r». and eke.
prop, of, 139.
Photo-chronograph. Sqtiire-Crehorr.
1133.
Photometer. Bunsen type. 535.
Photometers, integrating type, 539- i
Physical constants of copper wire, j
143.
prop, of alloys, table of. 134-140.
of metals, table of, 134-140.
quantities, table of, 6.
^
INDEX.
1573
X^k^akaliflche Reichaanstalt res.
unit, 30.
Piles, arrangement of, 1292.
foundation on, 1291.
safe load on, 1291.
IPilot brush, use of, 340.
IMpe bends, 1431.
covering, relative value of. 1422.
flanges and bolts, strength of,
1431.
dimensions of, 1430.
high pressure, screwed, 1430.
high pressure, shrink, 1432.
standard, 1433.
iron, elec. welding of, 1272.
lines, oonstr. of, 869.
riveted hydraulic, wt., safe head,
1409.
Pipes, diam. of steam and exhaust,
diagram of, 1419.
<limensions of riveted steel, 1467.
equation of gas, 1418.
of steam, 1418.
formula for riveted steel, 1467.
friction of water in, 1374.
loss of head due to bends in, 1374.
riveted steel, 1466/
sizes for feed- water, 1373.
of steam and gas, 1419.
standard dimensions of extra
strong. 1427.
standard dimensions, of wrought
iron, 1419.
thawing by electricity, 1531.
wooden-stave, 1468.
Piping, steam. U. S. navy spec, for,
1163.
Pitch, specific inductive capacity of.
227.
Planers, power required for. 1516.
Plants cell, advantages of, 880.
Plate box poles, 632.
glass, spec. ind. cap. of. 36.
surface for batteries, area of. 883.
Plates, appearance of battery, 874.
buckling of. 881.
of batteries, cadmium test of, 878.
safe working prssure for flat, 1332.
types of, 874.
Plating baths, 1233.
Platinoid, fusing effect of current on,
217.
phjrg. and elec. prop, of, 139.
wire, properties of. 202.
Platinum, fusing effect of current on,
217.
in electrolyte, test for, 877.
phys. and elec. prop, of, 139.
silver wire, properties of, 202.
spec. res. of, 132.
standard of light, 532.
temperature coef. of, 133.
wire, properties of, 202.
Plow, metropolitan street railway,
839.
suspension, 840.
Plug tube switches, 965.
Plunger electromagnet, law of, 127.
electromagnets, shapes of. 128.
magnets, range of, 130.
Pneumatic tires, data on, 1225.
Poggendorff method, comparison of
E.M.F. by, 77.
Polar arc, chord of, values of. 371.
duplex, 1044.
relay, use of, 1044.
Polarity of transformer, 405.
Polarisation, def. of, 14.
of storage cell, 879.
of X-rays, 1248.
PoUrised bells, biased. 1103.
constr. of, 1076.
use of, 1114.
Pole face, dimensions of, 363.
faces, shape of, 356.
line construction, 630.
lines for high tension work, 871.
pieces, faces of, 363.
transpositions, 1082.
unit strength of, 4.
Poles, determination of number of,
355.
j of induction motor, 426.
! plate box type, 632.
' use of green wooden, 806.
wooden, contents of, 633.
Polyphase apparatus, circuit
breakers for, 953.
generator, def. of, 502.
induction motor, theory of, 422.
1574
INDEX.
Polyphase induction motor, power
of. 423.
starting torque of, 423.
induction wattmeters, 1003.
integrating wattmeters. 1004.
lines, transposition of. 287.
meters, connections of, 1020.
constants of, 1031.
installation of, 1023.
service connections of, 1023.
testing of, 1020.
motor protected by circuit
breakers, 954.
Porcelain, spec. ind. cap. of, 37, 227.
Portable integrating wattmeters,
data for, 1010.
sub-station, 819.
telephone switchboard , 1141.
testing battery, 18.
Portland cement, wt. of, 1293.
Position indicators, U.S. navy. 1202.
Post-office wheatstone bridge, 31.
Potassium chlorate, production of,
1242.
oyaliide, production of, 1240.
use ol, 1233.
Potential betw. plates of batteries,
test of, 878.
drop in feeders, 788.
energy. 3.
measurement of, 40.
regulator, three-phase induction,
409.
regulators, 467.
def . of, 603.
rise due to transformem. 479.
transfonneiB, descr. of. 94.5.
Potentiometer, des. of, 47.
method, E.M.F. of batteries, 03.
use of, 47.
Pound, 1499.
calorie, 1511.
-degree, C. value of, 12.
Power ammunition hoists, U. 8.
navy, 1191.
and light cables, 320.
Asrrton and Sumpner method for
meas. A.C., 71.
carrying capacity in three-phane
cables, 216.
Power circuits, res. of, meas. of, SO.
consumpuon in factories. 1517
consumption of ears, 658.
curve for railway motora, fM.
curves, altera, curreot, 70.
for reducing cost of. 808.
for trolley oars, 652.
de6nition of, 3.
distribution, diseusaion of. 262.
system, A.C. railway. 718.
electric, def . of, 5.
meas. of, 507.
factor compensation. 1002.
def. of, 279.504.
in three-phase circulta, 72
of transformers, 458.
varied by use of synehr. motcn,
292.
for cars, 656.
house, electrolytic action neax,
862.
in altem. circuit, meas. of, 69.
in six-phase circuits. 477.
international unit of, 10.
light and heat, in xcsidenees. coct
of, 1287.
light and heat in isolated plants,
cost of, 1285.
lines, transposition of, 285.
loss, formula for, 265.
in lead sheath of cables, 293.
in line, 261.
mechanical, meas. of. 507.
of polyphase inductaoo motor,
423.
of water flowing in a ixpe, 1462.
-operated switchboards, 906.
plants, chimney protection for,
1281.
plants, lightning arresters in, 983.
required for automobiles, 1224.
for electric cranes, 1527.
for machine tools, 1516.
for street railways, 656.
to drive madiinery. 1515.
station construction, dbart of,
1280.
depreciation of, 770.
design of, 866.
efficiency of machines in. 663.
INDEX.
1575
Po'vrer station for railways, 815.
ssrstem, U.S. Navy. 1183.
three-phase, meas. of, 72.
to drive machine shops, 1518.
transmiasion, classif. of, 864.
kMses in, 1629.
tranaformera for three phase,
478.
voltage for, 870.
used by machine tools, 1515.
Preliminary dynamo dimensions,
checking of. 363.
Prepasonent wattmeters, 1010.
wattmeteni, Fort Wayne, 1012.
Pressure gradients, descr. of, 283.
drop in parallel distribution
system, 279.
drop, formula for» 264.
mean effective steam, table of.
1442.
of water to 1000 ft. head., 1465.
working, for cylindrical shells of
boilers, 1330.
Prevention of electrolysis, 861.
Primary batteries, action of, 14.
Primer for gun firing, 1213.
Principle of magnetic circuit, 109.
Printing machinery, power to run,
1525.
plants, electric heat in, 1269-1270.
Private telephone lines, 1088.
Production of metals, 1232.
Projectiles, velocity of, test of, 1128.
Projectors, search li^t, 575.
U. 8. Navy. 1179.
Prometheus system, electric heating'
1257.
Prony brake, formula for, 1515.
test, 395.
Propagation of waves, 1058.
Properties of aluminum wire, 194.
of dielectrics, 227.
ofgalv. iron wire, 34.
of saturated steam, table of,
1404.
above a vacuum, 1406.
of wires and cables, 131.
Propulsion, electric, Leonard's sys-
tem of. 354.
Protected third rail, cost of, 835.
Protection against high potentials
on A.C. circuits, 981.
of buildingi from lightning, 1289.
of chimneys, 1281.
of steam heated surfaces, 1421.
of transformeiB against fire, 871.
relays, table of, 960.
Protective relays, 956.
wires, use of, 982.
Protectors, telephone. 1088.
Puffer's modification of Kapp's
dsrnamo test, 389.
test of street car motors, 392.
Pulleys, 1487.
rules for, 1487.
to find sise of. 1487.
Pull of electromagnets, curves of,
129.
of electromagnets, formula for,
110.
-off curve construction, hangers
for. 647.
on armature conductors, formula
for, 351.
Pulsating current, definition of, 502.
Pulsation, def. of. 505.
Pump exhaust, 1377.
Pumping back test of motors. 397.
test of two dynamos, 388.
hot water, 1367.
Pumps, 1367, 1443.
air, 1445.
and condensers, 1443.
double cylinder, sixes of. 1370.
circulating, 1445.
single cylinder, sizes of, 1369
sixes of direct-acting, 1368.
Puncturing voltage for dielectrics,
228.
voltage of mica, 234.
Pupin telephone system, 1107.
4(,aadniiit electrometer. 40.
Quadruplex telegraphy, 1051.
Quality of light, 600.
of steam by color of issuing jet,
1400.
Quantity of electricity, def. of, 5.
meajt. of, 25.
symbol of, 8.
1676
INDEX.
Quantity of electricity, unit of, 4.
Quarts, spec. ind. cap. of, 37.
Quick break switches, 964.
Itadiitl brick, bond in, 1340.
for chimneys, 1341.
telephone system, 1117.
Radiation, laws of, 528.
of heat in ducts, 214.
Radiators and oonvectors, 1263.
Radioecopio images, examination of.
1255.
Radius <tf eurvature, 616.
of gyration, 1303.
compound shapes, 1303.
table of least, 1304.
Rail bonds, testing of, 801.
curvature, 616.
joints, testing of, 801.
Potter type, 830.
testers 802.
welding, electric, 1273.
thermit system, 778.
Rails and bonded joints, rel. value
of. 780.
electrolytic action on, 855.
impedance of steel, 705.
ingredients of, 780.
resistance of, 821.
specifications for, 830.
weig^ht of, 615.
Railway booster calculations, 809.
system, 807.
bonds, requirements for, 775.
types of, 772.
circuits, drop in, 796.
testing drop in, 804.
tests of, 798.
conductors, dimensions of, 791.
conduit sjnstems of, 835.
depreciation, table of, 770.
electric, system of operating, 613.
energy of electric, 706.
equipments compared, 719.
weights of, 730.
machinery, depreciation of, 770.
motor characteristics, 685.
combinations, 760.
motors, 614.
A.C. type, 707.
Railway motore, arma.tiire wiadiaffs
of, 348.
capacity of, 673.
characteristic curves for. 664.
efficiency of, 803.
installation of, 745.
rating of, 523.
selection of, 524.
speed-time curve for, 669.
standard sixes of, 729.
test of, 397.
temperature of, 675.
torque of, 731.
non-arcing lightning arrestcn,
985.
overhead conductors, 785.
power station, 815.
service boosters, 813.
shop, power required in ideal,
1521.
speed and eneigy curves. 680.
sub-stations, equipment of, 942.
system, load factor of, 785.
ties, durability of, 619.
turnouts, 620.
Rake of poles, 633.
Range finder, Fiske. 1211.
finders, lights for, 1148.
indicators, U. S. Navy, 1204.
<^ carbons, 577.
of solenoids, 130.
Rape-seed oil, spec. ind. cap. uf,
37.
Rapid fire guns, firing meefaaatsm
for, 1149.
Rated terminal voltage, def . of. 513.
Rate of acceleration. 666.
of deposit, 1235.
Rates, gas and electric, comparisoa
between, 1261.
df charge of batteries. 883.
of discharge of batteries. 883.
of storage batteries, 874.
Rating of fuse wires. 1275.
of generators, 505.
(rf illuminants, 540.
of railway motors, 661. 673. 729.
Ratio of transformers in three-|diase
system, 471.
test of tranafonner, 491.
>
INDEX.
1577
tayleigh's method. E.M.F. of
batteries, 62.
laaotanoe coil for A.C. arc cir-
ooite, 466.
factora. table of, 266.
of three-phase line, inductive.
245.
of transmiasion drouits, 238.
aymbol of, 8.
-voHa for A.C. lines, 280.
Reaction of alternator armatures.
414.
of annatiins, 850, 364.
H— otive ooib, use of, 982.
factor, def . of, 504.
Reobotors, def. ef, 503.
Reading, illumination for, 602.
Receiver, Bell telephone, 1070.
capacity, 1443.
with detector, 1065.
Receivers, coherer with jigger, 1064.
wireless telegraph, 1063.
Recording meters, Bristol, 1086.
wattmeters, Duncan, 1000.
G. E., testing. 1030.
Thomson. 098.
Records of temperature test. 381 .
Rectifying apparatus, losses in,
meas. of, 512.
Reduced deflection method, res. of
batteries by, 60.
Reed method, electric heating. 1257.
Reflned iron, qualities of, 824.
Refineries, copper, 1238.
Refining of copper, 1235.
of metals, 1232.
of silver, 1238.
Reflecting galvanometer. Kelvin
type, 23.
Reflections, coefficients of, table of,
593.
Regulating battery, 888.
devices for induction motors, 428.
reactance coil, 466.
relays, 956.
Regulation, importance of, 545.
of arc lamps, 576.
of dynamos, test for, 382.
of generators, 870.
cf maohineB, 513.
Regulation of transformers, 458.
by calculation, 492.
comparative, 455.
table of. 498.
test of. 491.
of voltage of transformers, 452.
Regulations of Board of Trade. 781.
Regenerative X-ray tubes. 1251.
Regulators for A.C. generators. 400.
for separate circuits. 469.
of potential, 467.
three-phase induction potential,
469.
Reinforced concrete, 1292.
Relative conductivity, 132.
efficiency of large and sm&ll trans-
formera. 459.
Relay, General Electric A.C. over-
load. 961.
low voltage A.C. 962.
D.C., 961.
overload, A.C, 962.
over-voltage, D.C, 960.
reverse-phase A.C, 962.
underload D.C, 962.
Westinghouse A.C. overload, 962.
D.C. over-voltage, 962.
time limit, 960.
Relays, auxiliary, 956.
classification of. 955.
commonly employed, 960.
definite time limit. 956.
instantaneous, 956.
inverse time limit, 956.
protection of A.C systems by, 950.
protective. 956.
regulating, 956.
reverse current, 961.
signalling, 955.
Reliability of service, switchboards
built to insure, 929.
Reluctance, definition of. 5.
value of, 7.
Reluctivity, definition of, 5.
value of. 7.
Remedies for electrolysis, 861.
Remote control panel switchboard.
906. 928.
control switches for equaliser cir-
cuits, 962.
1578
INDEX.
Removal from service of storctgc
batteries, 881.
Renewals of lamps, 547, 556.
Repeater, Atkinson, 1048.
duplex, 1049.
Ghegan, 1042.
Milliken, 1041.
Weiny-Pbillipe, 1043.
Repeaters, use of, 1041.
Reservoirs, storage, 867.
Residential plant, cost of inaint. of,
1287.
plant, installation of, 897.
Residual magnetism, def . of, 108.
Resin, spec. ind. cap. of, 37.
Resistance box, decade type, 32.
control of battery discharge, 891.
curves on air, 659.
definition of unit of, 5.
due to gravity, 1224.
for arc lamps, 581.
high voltmeter, 75.
in overhead lines, 798.
returns, 798.
bi rotor of induction motors, 428.
In stator of induction motors,
429.
low, meas. <^, 59.
magnetic, definition of, 5.
meas. of, with olunmeter, 57.
with volt and ammeter, 78.
measurements, 56.
of A.C. circuits, 259.
conductors, effective, 238.
of aerial lines, 61.
of aluminum wire, 194, 196.
of armature, meas. of, 401.
of batteries, 60.
of bonds, 776.
of brushes, 362.
of cables, meas. of, 330.
of carbons, 577.
of cells, external, 20.
internal, 20.
of conductors, 61.
table of, 266.
of copper wire, table of, 148.
of dilute sulphuric acid, 1229.
of Driver-Harris wire, 207.
of field coils, meas. of, 401.
Resistance of galvanonieiei»» 60.
of German sih'er wire. 208.
of gutta-percha. 231.
of house circuits, 61.
of light and power ctraiita. bmhi
insulation, 80.
of multiple circuits, 5.5.
of plating bath. 1235.
of nils, 821.
of steel. 825.
of storage batteries, S83.
of stranded aluminum wire. uUt
of. 198.
of sulphate of copper, 1231 .
of sine, 1231.
of track rails, 779.
of transformer, mea«. of. 486.
of trolley and track, 798.
of water rheostats, 33.
of wiring system, insulatioo. 82.
of working batt«'ies, 61 .
practical standard of. 30.
specific, 131.
magnetic, 5.
symbols of. 7.
table of gal v. iron wire, 34.
to traction. 1^5.
type furnace, 1244.
unit of. 4.
variation with temperature of. 22S. ;
-volts for A.C. lines. 280.
wires, properties of. 202.
Resistances, high. meas. of. 79.
small, meas. oi, 79.
Resisting moment of beanas, ISffi^
Resistivity, definition of, 9.
symbol of, 8.
Resonance, curves of, 1216.
theory of, 1215.
Retardation, rate of, 668.
Retentiveness, def. of. 108.
Retraction motor for gun operadrc
1134.
Return booster system, 808.
call bell system. 293.
circuit, 771.
current, division of, 800.
drop of ground, test of, 790.
Returns, drop in, 798.
regulation for railway, 781.
INDKX.
1579
Reverse current circuit breaker, 950.
current relay, 961.
-pliaae A.C. relay, 962.
Reverser. multiple unit Bsmtem, 762.
Reversible booster, use of, 894.
Reversing current in armatures, 361 .
Revolution indicators, U. S. Navy,
1204.
Revolving field altematore, 409.
Rheoetatic controller, 754.
oontroUers, list of, 756.
Rheoetate, temperature rise in, 520.
water, 33.
Right of way for pole lines, 871 .
Ring armature, windings of, 342.
down trunks, 1096.
method, determ. magn. values by,
91.
type armatures, 341.
Ringing keys, 1090.
Rise and grades, 617.
ci potential due to transformers,
479.
of temperature in armatures, 349,
358.
of commutator, 362.
in dynamos, test of, 378.
in field coils, 352.
in transformers, test of. 483,
491.
in transforraere, 447, 498.
meas. of, 518.
U. S. Navy generators, 1158.
Ritchie's photometer. 536.
Riveted bonds, 774.
Roadbed, depreciation of, 770.
Road surface material, 1225.
Rock, foundations on, 1290.
salt, spec. ind. cap. of, 37.
Redding of cables, 319.
Rod float gauging, theory of. 1471
Rods, lightning, installation of , 1278.
Roebling galv. telegraph wire, prop-
erties of. 200.
steel telegraph wire, properties of,
201.
wire gauge, 141.
Rolling stock, depreciation on,
770.
Room lighting, data on. 597.
Rope driving, 1490.
hemp, wt. of, 1494.
horse-power of transmission, 1492.
manila, velocity of, table of, 1492.
wt. and strength of, 1494.
Ropes and belts, slip of. 1493.
horse«power of manila, 1491.
of manila, diagram of, 1492.
strain from loads on inclined
planes. 1494.
Rosa curve tracer, 50.
Rosendale cement, wt. of. 1293.
Rosin, specific inductive capacity of,
227.
Rotaries, overspeedingof , prevention
of, 961.
starting diagraun of connections
for, 920.
starting of. 440.
liotary compensator turret turning
system, 1189.
Rotary converter circuit protection
by relays, 959.
def. of. 503.
panel. General Klectric D. C,
925.
equipment of. 919, 924.
sub-station, 816.
Rotary converters connected to'
transformers, 442, 476.
descr. of. 436.
for six-phase system, 475.
in sub-stations, 814.
starting, diagram of connections
for, 920.
voltage between collector rings
of, 439.
Rotary field of induction motor, 425.
induction apparatus, temp, rise
in, 520.
transformers, armature windings
for. 441.
Rotating field in wattmeters, 1000.
Rotation of conductors around pole,
109.
Rotor, core of, 425.
definition of. 423.
resistance in, 428.
slots, number of, table of, 427.
windings, commutated, 429.
1580
INDEX.
Rowland method, determ. maicn'
vaiu«B by, 01.
Rubber covered cables, eairying
capacity of. 208.
wire and cableii, prop, of, 161.
underwriters' test of, 161.
Rubber, electrical properties of, 229.
insulated cables, carrying capac-
ity of, 210.
cables, data on, 214.
telegraph cables, 180.
wires and cables, tables of, 164-
172.
insulation test of, 230.
specific inductive capacity of. 227.
tires, data on, 1225.
Rules f oroonducting boiler tests, 1384.
Rumford*8 photometer, 536.
Ryan electrometer, 50.
Ryan*B method, mess, of wave form
by, 40.
Iroaui^ elec., cost of operating,
1203.
Sag and tension in wire spans. 218.
for aluminum wire, limit of, 225.
in wire spans, calc. of vertical, 222.
gage direct reading ohmmeter, 58.
Safe load on wooden beams, chest-
nut» 1310.
hemlock, 1310.
southern pine, 1320.
spruce, 1318.
white cedar. 1310.
white pine, 1318.
yellow pine, 1319.
load on brickwork, 1322.
on steel beams, 1310.
temperature for field coils, 352.
Safety valves, 1382.
Philadelphia rules, 1383.
rules for pop valves, 1383.
rules governing, 1382.
Saline solutions, conducting power
of, 005.
Salt solution for water riieostats, 34.
Sand and cement, A.S.C.E, recom-
mendations, 1204.
and cement, fineness of, 1204.
foundations on, 1200.
I
Sandstones, eraahins load. 1333.
Sangamo intcgmtinc meter. 1006.
wattmetatB, tesUnc of. 1035.
Saturation faetor. def . of. 505.
teet of dynamos, 400.
S.B. resistance wire, 207.
Scale, galvanometer. 24.
solubility of, 138S.
Scales, instrumeot, fisurinc ef • ^Mi
Schedule for 35-toii oar. 658.
Schmidt chronosoope, 1131.
Schuckertsearohli^ta, 1123.
Schults ehronoooope, 1130.
Scott meUiod of eonnecting ooovcn-
ers and tnuMfondierB, 477.
Screwed contact, eiirrent denaty
for, 442.
Searchlight carbons. 579.
projectozB, 575.
Searchlights, data on. tablei< erf. 11 27.
intensity of light of. 1125.
mirrors of, 1125.
Schuekert type. 1123.
UM of, 1123.
U. S. Navy. spec. for. 1179.
Secohmmeter, mesa, mutual ind.
by. 60.
Secondary current, transforBiefs
for constant, 462.
standards, cheeking of. 1013.
Second, definition of. 2.
Sectional rail, Westinghouae rsil-
way system, 846.
Sections, elements of usual, 1303.
of trolley system, laying out. 785.
Seeley's cable connectors. 100.
Segments, commutator, number of,
361.
Selective telephone systems, 1102.
Selenium, spec. ind. cap. of, 37.
spec. res. of, 132.
Self-inductance, meas. ooef . of ind.
by, 65.
with altera, current, meas. of. 06.
Self-induction, coefficient of, 64.
def. of, 238.
formula for, 230.
in solid iron wire, table d, 248.
in stranded wires. 241.
of traasmlasion drouits, 238.
INDEX.
1581
alf-induetion standard, Ayrton and
Perry's. 68.
eparate circuit regulators, 469.
eparately excited dsmamo, 338.
ep&rating calorimeter, 1398.
sjMiratorB, steam, 1380.
eries A.G. regulator, Q.E. type, 466.
booeters for railway servioe, 813.
oondeneers in, 63, 324.
oonneotion of batteries, 19.
dsmamo, descr. of, 336.
ext. characteristio curve of, 337.
limit switch for railway control,
769.
multiple 8wit(9iboards, 1092.
parallel controller, 753.
controllers, list of, 755.
party lines, 1108.
telephone system, 1076, 1109.
transformers, 464.
Service box cover, cut of, 315.
box. def. of, 301.
boxes, constr. of, 302.
capacity of railway motora, 675.
connection of polyphase metere,
1023.
meter, tests of, 1015.
reliability, switchboards built to
insure, 929.
Sesame oil, spec. ind. cap. of, 37.
Sewer connections, cost of, 303.
Sewing machine, power to run, 1525.
Shafting, centers of bearings of,
1483.
deflection of. 1482.
hollow. 1485.
horse-power of iron, 1481.
tables of. 1484.
laying out. 1485.
pulleys, belting, rope driving,
1481.
rules for, 1481.
Uhaftfl. armature, 341.
hollow. 1485.
ghallenberger meter, testing of, 1028.
Shallow trenches, manhole conntr.
for, 319.
Shape of moving body, effect of, 659.
of pole faces. 356.
ShaperB, power required for, 1520.
Sharp-Millar's photometer, 539.
Shawmut soldered bond, 772.
Shearing strength of woods, 1316.
Shear, vertical-beams. 1308.
Sheathing core, formula of. 142.
Sheath, metallic, capacity of wires in,
251.
Sheet metal, permeability of, 89.
Sheldon method, meas. low res. by,
59.
Shellac, spec. ind. cap. of. 37. 227.
Shell type transformers, coils for,
444.
Shelves for buii-bars. 933.
Ship, condensation of steam in pipes
aboard, 1415.
Ships, d3mamos in, gyroetatic action
on. 353.
Shoes, cast iron magnet. 352.
third rail. 832.
Short circuit in armature, test for,
402.
connection winding of armatures,
343.
Shunt booster, use of, 892.
boxes, galvanometer, 29.
dynamo, external characteristic of,
339.
internal characteristic of, 339.
dynamos, regulation tests of, 382.
winding of compound wound
machine, 369.
wound dynamos, des. of, 336.
Shunted detector, 1065.
Shunts, ammeter, 41.
Shut-down of plant, provision
against, 929.
Side brackets for trolley line, 635.
Siding suspension, 638.
Siemens' electro-dynamometer, 42.
ohm, value of, 131.
Sights, night, electric. 1148.
Signal corps wireless telegraphy,
1145.
lights, U. S. navy. 1181.
stranded wire, galv., properties of
200.
system, requirements of, 623.
Signalling, automatic block, 622.
relays, 955.
1582
INDEX.
Bignalling, syntoDic. 1050.
Silicon-broDae, phys. and eiec. prup.
of. 140.
Bilt, effect on storage of, 869.
Silver, phys. and elec. prop, of, 139.
plating, 1234.
refining of, 1238.
spec. res. of, 132.
temperature coef. of, 133.
voltameter, description of, 10.
Simplex system, electric heating,
1257.
Sine curve, discussion of, 404.
wave, def . of, 506.
Single conductor cables, watis per
foot lost in. 212.
conductor cable cambric ins.,
tobies of. 179-183.
conductor wire toble, U. S. navy,
1170.
oontoct tmnsmlttere, 1071.
duct conduit, adv. of, 301.
overhead wire, capacity of, 250.
Single-phase A.C. motors, 421.
A.C. railway system, 707.
A.C. sub-stotion, views of, 943.
air-blast transformers, 452.
armature winding, 411.
circuit, charging current per 1000
feet of, 253.
circuits, self induction in, 239.
feeder panel, equipment for, 916.
induction wattmeters, 1003.
line, capacity effect in, 249.
potential regulators, 467.
railway, distribution system for,
718.
railway motor characteristios, 713.
rotory converter, 436.
transformer connections, 472.
transformers vs. multl-phaae, 871 .
transmission circuit, calc. of, 280.
wiring examples, 272.
Single truck cars, power for, 656.
Six-phase, changing three-phase to,
475.
circuits, power in, 477.
Size of conductors for parallel D. C
distribution, 284.
of generator units, 870.
451.il
Sizes of GBiixHW, 578.
of railway nootors. 729.
S.K.C. high voltage testing
lif^tning arrester. S90.
Skin effect, 1061.
def. of. 236.
factors, toble of, 237.
Slate cut-oute, ras. bet v.
of, 86.
for switchboards, SM)7.
Slawaon*s signal block oyatem, 627.
Slide-wire bridge, 58.
Sliding trolley collector, 641.
Slip of induction motor, toUe dL
425.
of ropes and beito, 1493.
Slipper shoe for third rail. 833.
Slot sises, armature, values of. JTt
Slots in field-frame of indnctioe
motor, 426.
of armature cores, deslgpn of. 357.
Slotted or toothed type annatares.
341.
Slotters. power required for, 1220.
Smashing point, def. of, 5M.
Small resistonoes, meas. of, 79.
Smelting by Staasano pfooeas, 1274.
electric, 1247.
def. of. 1232.
Smooth body aimatores, ajdvmaUgm
of. 341.
Sneak current proteotor, 1068.
Soapstone for switehboards, 907.
Sodium, cyanide of, productfen oC,
1246.
hydrate, production of, 1239.
production of, 1241.
Soft iron ammetera, 41.
Soldered bonds, test of, 773.
types of, 772.
Soldering irons, deotric, 1270.
Solenoids, eharacteristica of, ctures
of. 129.
coefficient of self ind. of, 65.
pull of iron-olad, 127.
tractive effort of, 130.
Solid baolc transmittens, 1072.
copper wire, G. E. Go., prop, of,
toble of, 162.
prop, of, table of, 154.
INDEX.
1583
lid tires, data on, 1225.
lids, spec. ind. cap. of, table of,
36. 37.
lubilitieB of Boalfr>inaking mater-
ials, 1363.
•and, propaiiation of, 1060.
lurces of light, intrinsio briichtnetiB
of, 520.
laoe occupied by D.O. oov. wire,
table of, 123-126.
occupied by S.C. oov. wire, table
of, 121-123.
required by turbines vn. recipro-
cating engines, 1454.
pacing of beams for various loadn,
1315.
pan construction, 644.
wire, dip in, 634.
material for, 635.
Ipans, chart for long. 220.
chart for short, 221.
tension and sag in wire, 218.
Ipark gap curve, 233, 462.
gap, meas. of, 517.
points, oonstr. of, 517.
Sparking at commutator, 805.
at switches, 048.
distance across needle points, 462.
distances, table of, 526.
of brushes, 805.
Sparks, chemical effect of electric,
1232,
length of, curves of, 040.
Bpedal cables for car wiring, prop,
of, 173.
lamps, navy, table of, 1178.
Specifications for det. ampere, 10.
for det. intern, volt, 10.
for paper ins. telegraph cables,
180.
for paper ins. telephone cables,
188.
for submarine cables, 180.
for switchboards, 047.
for 30 per cent rubber compound,
229.
for telephone cables, 1083.
for transformer oil, 500.
for transformen, 408.
U.S Navy, 1153
Specifications for wiring, U. S. Navy,
1167.
Specific conductivity. 132.
energy dissipation in arm. core,
107.
gravity and unit weights, tables
of. 1513.
gravity, table of, 1512.
heat, mean, of platinum, 1500.
of gases and vapors at con-
stant pres., 1511.
of water, 1511.
heats of metals. 1500.
inductive capacity, 4, 38.
measurement of, 38.
of dielectrics, 227.
of gases, table of. 35.
of liquids, table of, 37.
of solids, table of, 36, 37.
magnetic resistance, 5.
value of, 7.
resistance. 131.
of conductors, table of, 132.
of liquids, table of, 133.
thermal conductivity of dielec-
trics, 234.
Speech, definition of, 1060.
Speed and energy curve, 680.
curves of railway motors, 686.
error table for wattmeters, 1032.
headway and number of cars, 660.
of cars, diam. of wheels to obtain
certain, 655.
of dynamos, formula for, 356.
of induction motors, 424.
of power generators, 870.
of wattmeters. 1020.
recorders, U. S. Navy, 1212.
run of N. Y. C. locomotive, 743.
-time curve, 667.
Spendersfelds line, details of, 651.
Spermaceti, spec. ind. cap. of, 37.
Sperm oil, spec. ind. cap. of, 37.
Spherical dandle power of lamps,
540.
Spiegeleisen, phyn.and elec.prop. of,
137.
Spikes, table of, 618.
Spitting^ff discharges, 1278.
Sprague multiple unit control. 761.
1584
INDEX.
Bprinc jaoks, use of, 1080.
Square roots, table of, double, 45. 46
fiquire-Crehore photo-chronograph,
1133.
Squirrel-oage induction motors, rotor
slots for, 427.
Staggering trolley, 044.
Standard candle, 530.
odi, oonstruetion of, 11.
description of, 10, 10.
filling of. 13.
used with potentiometer, 47.
condensers, oonstruetion of, 38.
conductors* N. E. C, prop. of.
toble of. 162.
copper wire strands, prop, of,
table of, 150.
of resistance, construction oi, 30.
of self-induction, Ayrton and
Perry's, 66.
symbols for wiring plans, 200.
Standardisation rules A.I.E.E.. 501.
Standards of light, 530.
Stanley lightning arrester, 000.
Star connected armature windings,
413.
connection of transformer, three-
phase, 473.
of winding, 404.
Starting current test of synchronous
motors, 400.
devices for induction motoni, 428.
induction motors, methods of, 018.
of rotaries, 440.
rotary converters, diagram of
connection for, 020.
torque of polyphase induction
motor, 423.
Stassano process for elec. welding,
1274.
Static dischargers, 002.
ground detectors, installation of,
042.
interrupter, 003.
machines, use for X-ray of, 1252.
transformer, def. of, 443.
wave, action of, 003.
Stationary impedance of induction
motora, 308.
Stator, core of. 425.
Stator, definitkm of. 423.
resistance in» 420.
Stays, boiler head, 1333.
Steady strain discbargM, 127&
Steam. 1327.
Steam boiler, efficieoey of. Its
settings, 1334.
measurements of, 1336.
strength of riv. shell. 1330.
Steam boilers, cylinders of, 1^.
flues ol, 1327.
gas passages and flues of. 1329.
grate surface per b.-p. of. 1339.
heating suifaoe oC« 1328.
tubes of. 1328.
per h. p., 1329.
hor. return tubular, 1327.
setting of, 1335.
horae-power of. 1327.
points in selecting, 1327.
scotch or marine. 1327.
types of, 1327.
vertical fire tube. 1327.
water tube, 1327.
working pressure of, 1330.
Board of Trsde rale, 1333.
Philadelphia rule. 1332.
U. S. statutes, 1332.
Steam en^nes, 1434.
and dynanaos, standards ei,
1435.
brake horse-power of, 1440.
cylinder ratios of. 1441.
horse-power of, 1440.
. ind. horse-power of, 1440.
mean effective preeeure table of.
1442.
nominal horse-power of, 1440.
receiver capacity of, 1443.
regulation of, 514.
tests of various types of, 1413.
Steam, flow throu^ pipcs ^-
1417.
flow to atmosphere of, 1416.
to lower pressures of, 1416.
heating, boiler horae-power, 1415.
moisture calorimeter disgisiD.
1307.
in, determination of, 1304.
tables of. 1306.
INDEX.
1585
Bteam pipe oovering. cost and heat
lom of. 1423.
electrioal tests of. 1422.
diagram of. 1423.
heat loss in. 1423.
miflcellaneous substances for,
1425.
relative economy of, 1424.
value of, 1422.
Steam pipes, 1417.
condensation in, 1415.
aboard ship, 1415.
heating, 1415.
loss of heat from. 1421.
Steam piping, U. S. navy spec. for.
1163.
ports and paaeages, 1443.
properties of saturated. 1404.
1-15 lbs. abfl., 1404.
quality by color of issuing jet.
1400.
aeparatoni, 1380.
superheated, 1413.
table. DeLaval turbine, 1458.
total heat of, 1511.
Steam turbine. 1451.
Curtis. 1455.
DeLaval steam flow, table of.
1458.
tests of, 1452.
Parsons. 1453.
vanes in Westini^ouse-Parsons,
1453.
Steam turbines, relative floor space
of, 1454.
relation of foundation to h.-p. of
1457.
U. S. Navy spec, for, 1160.
Steam, volume of. tables of. 1404.
weight of. tables of, 1404.
Steel and iron, ageing of, 455.
eleo. wdding of. 1271.
magnetic fatigue of, 455.
permeability curves of, 00.
wire, constants of, 100.
Steel chimneys, brick lining of, 1343.
cost of, 1343.
foundation siie of, 1343.
field magnet yokes. 352.
for third rail, qualities of, 822.
Steel frame buildings, eleotrolsrsis in,
859.
magnetic qualities of, 01.
permeability of. meas. of, 04.
poles, 633.
weight of, 633.
production of, 1247.
rails, 825.
impedance of. 705.
resistance of, 825.
strand wires for trolleys, 642.
telegraph wire, properties of. 201 .
weight of. 1204.
wire, properties of. 201.
use in telephony of, 1082.
Steering-gear, navy spec, for, 1200.
Steinmetz hysteresis formula, 08.
Step-by-step method, hysteresis
tests by. 101.
telephone systems, 1102.
Step-down transformers for Y-dis-
tributions, 478.
Stepping-down arrangement for long
distance transmission. 474.
Steppin0*up arrangement for long
distance transmission. 474.
Stem's duplex, 1050.
Stillwell potential regulator, 467.
Stoking, mechanical vs. hand firing.
1350.
Stone, crushing load of, 1322.
foundations. 1203.
Stop watch, use in meter tests of.
1015.
Stops of car. table of frequency of.
658.
Storage batteries, automobile, 1227.
capacity of. 874, 883.
care of, 1228.
central station, three>wire sys-
tem, 003.
charge and discharge rates of,
883.
charging of, 880.
connections for charging, 800.
constant current, booster sys-
tem, 001.
dimensions of, 883.
discharge rate of, 874.
efficiency of, 870.
1586
INDEX.
Storage batteries, elemwita of, 872.
erection of, 884.
instaUation of, 885.
internal reeistanoe of, 883.
load regulation by, 888.
loaB of charge of, 884.
polarisation of, 879.
removal from service of, 881.
requiremoBts of, 874.
sulphation of, 881.
tests of, 882.
theories of, 872.
three-wire system. 899.
to carry load peak, 886.
troubles of, 881.
uses of, 888.
variation of efficiency of, 884.
voltage curves of. 883.
weight of, 882.
Storage battery booster equipment,
902.
boosters, circuit breakers pro-
tecting, 952.
capacity, 900.
discharge, control of, 891.
plant, installation of, 897.
plates, cadmium test of, 878.
types of, 874.
Storage reservoirs, 807.
Stoves, car, cost of operating, 1266.
Strains in ropes on inclinet^ planes,
1494.
Strain test, 381.
Stranded conductor, G. E. Co.,
table of. 163.
copper conductors, carrying cap.
of. 209.
wire, prop, of, table of, 155.
weather-proof aluminum wire, 197.
wires, self induction of, 241.
Strain, 1301.
Strands, standard copper, prop, of,
table of, 159.
table of wire, 142.
Stray power of dynamo, calculation
of. 391.
test of motor. 396.
Streams, estimating. 869.
Street car equipments, compared,
719.
Street car heating, electric, I365l
cars, lifting ctf, 806.
possible schedule for, 658.
excavation per conduit foot wA
of. 308.
lighting by arc lamps, 582.
Street railway booeter ssrstcm. ftF!.
circuits, test of, 798.
material required for one raSe d,
628.
motor characteristics, 713.
control, Leonard's system d,
354.
testing. 803.
motors, armature windinp cf.
348.
capacity of, 673.
characteristic cur\'e of, 664, 68&.
efficiency of, 663. 803.
rating of, 661.
ser\'ice capacity curves of. 67lt.
speed-time curve for, 669.
test of, 392. 397.
power station, 815.
Street railways, depreciatioa on,
table of. 770.
power required for. 656.
Strength of current, meas. of. 78.
of dilute sulphuric acid, table
of. 904.
of materials. 1301.
of riveted shell, boiler, 1330.
of wire lopes, 1325.
Stress, 1301.
Strut bars. 1314.
Submarine and und«7cround eshles,
tests of. 321.
cables. 188. 1083.
testing of, 381.
Submerged rheostats, wire for, 34.
Sub-station design, 814.
for railways. 815.
portable type. 819.
rotary, oonv^ter. 816.
sini^e phase A.C, vieini of,
943.
Sub-stations, drop between, 794.
equipment of, 942.
Substittltion method, res. meas. by.
56.
INDEX.
1587
oburtMin cars, tjrpeB of, 612.
ulpluite of copper, res. of. 1231.
of lead, use of. 873.
of sine, res. of, 1231.
•ulphation of storage batteries, 881 .
lulphur dioxide, spec. ind. cap. of,
35.
spec. ind. cap. of, 37.
ttilphuric acid, conducting power of,
table of, 005.
resistance of, 1229.
spec. res. of, 133.
streni^th of, table of, 904.
Sumpner's test of copper loss in
transformers, 497.
of iron loss in transformers,
496.
Superficial measures, metrical equiv.
1501.
Superheated steam, 1413.
economy of engines luiing, 1413.
Superheaters, 1413.
Supplies, approx. list of electric
work, 1531.
Supplying losses, electrical method
of. 389.
Surface contact plates, Ci. E. railway
system, 848.
railway, G. E. system, 847.
railway system, 840.
shoes, G. E. railway system,
850.
Surface insulation against electro-
lysis, 862.
measures of. 1499.
Suaoeptance, capacity, table of, 269.
symbol of, 8.
Bufloeptibility, magnetic, definition
of, 5.
value of, 7.
Suspended wires not on same level,
sag in, 223.
Suspension brackets, 635.
of trolley wires, 637.
Swapping of current, 859.
Swedish iron rope wire, 1325.
Switchboard, definition of. 906.
instruments, 940.
list of, 945.
meters, list of, 945.
Switchboards, A.C. and D.C., ro-
tary converter panels for, 924.
A.C. panels for. 912.
aluminum bare for, 91 1 .
arc. General Electric, 922.
central station, electrically op-
erated, 928.
panels for, 907.
connections on, 910.
constant current transf. panels
for, 922.
controlling, 940.
copper bars for. 909, 911.
D. C. exciter, 942.
feeder panel for. 928.
generator panel for, 924.
motor panel for, 928.
direct control panel, 906.
electrically operated. 929.
for battery plants, 808.
for hydro-electric plant, 931.
for transmission plants, 870.
frames for, 908.
General Electric D.C., rotary con«
verter panel for, 925.
generator. U. S. Navy, 1163.
hand-operated, 906.
remote-control, 928.
illuminating lamps for, 909.
induction motor panels for, equip.
of, 918.
insulation distances on, 912.
isolation of oonduoton on. 929.
material for, 907.
panel, design of, 906.
power-operated. 906.
reliability of service insured by, 929.
remote control panel, 906.
space behind. 907.
specifications for. 947.
single-phase panel for. equip-
ment of, 916.
sub-station, equipment of, 942.
telephone, common battery, 1098.
design of, 1080.
multiple, 1090.
portable, 1141.
series multiple. 1092.
temperature rise of devices on.
910.
r
1S88
INDEX.
Switchboards, three-phaM panels for
912.
rotary converter panel for, 919.
synohr. motor panels for, 919.
two-phase paneb for, 915
Westinghouse generator panel
for, 925.
rotary panel for, 925.
three-wire generator panel for,
926.
Switches disconnecting type, 985.
for equalizer cirauitB, remote con-
trol, 962.
for high potential, 957.
lever type, 963.
oil, operation of, 967.
plug tube tsrpe, 965.
quick break, 964.
sparking at, 948.
Switching devices, arrangement of,
935.
specifications for, 948.
Switch jaws, current density for,
442.
Symbols, dsmamo and motor section,
334.
electrical engineering, 1.
for wiring plans, 299.
fundamental, 1.
mechanical, 1.
table of, 6.
Synchronisers, descr. of, 416.
Synchronising of altematois, 421.
Ssmchronous oonvarter, def. of,
503.
hnpedence, 400.
field current, 383.
machines, def. of, 503.
losses in, meas. of, 510.
motor panels, equip, of, 919.
motors, starting of, 431.
tests of, 399.
theory of, 432.
used as oondensera, 292.
Synchroscope, inductor type, 417.
Synopsis of report, water power
property, 1460.
Sjrntonic apparatus, 1062.
signalling, 1059.
System. C. G. 8., 2.
of angular dist.
brushes 344.
of armature slot sases, 372.
of capacity per 1000 feet o
wim, 252.
of change of hysteresb by
457.
of charging current per IQOQ
of aerial circuits. 253-23S.
of closed circuit celle, 14.
of copper wire phys. const., I4L
of cost of duct matierial in
307.
of paving per sq. yd., 305.
of street excavation per
ft., 306.
of double square roots, 45-^
of eddy eutreat factors, 106.
of electrical and mffrhanirsl ub^
1258.
of energy and work units, 12.
of dissipation in arm. core. IC
of hysteretie constants, 99.
of inductive reactances, 242.
at magnetisation of
nets. 111.
of physioa] quantities, 6
of properties of galv. iron wire!
34.
of open eirouit cells. 15
of resistance of aluminum win
196.
of Driver-Harris wire, 207
of magnet wire. 112.
of self-induction in millihwnrya
241.
of specific ind. cap. of gases. 35.
of specific res. of oond., 132.
of wire gauges, 141.
Tables correcting length of msgne^
coil, 117-120.
of linear space occupied by D. C
CO v. wire, 123-126.
S. C. cov. wire, 121-123.
Tabulation of ccMre loss tests, 384.
Tan a. values of, 276.
Tangent galvanometer, des. of, 22.
track, hangers per mile for, 641
Tantalum lamps, 549^
candle-power of.' 553.
INDEX.
1589
^ Tapering of conductors, eoonomioal.
279.
of railway conductora, 703.
Teaser, use of, 477.
Teetli of armature ooreR, denign of,
357.
Telautograph, U. 8. Army, 1141.
Telesraph cablen, 189.
codes, 1052.
field, 1140.
fortress, 1140.
U. S. Navy engine, 1202.
-virire, galv. iron, properties of, 199.
hard-drawn, prop, of, 156.
steel, properties of, 201.
Tel^^raphy, American methods of,
1040.
closed circuit method of, 1040.
duplex, 1044.
European method of, 1040.
open circuit method of, 1040.
-wireless, U. S. Army, 1145.
Telephone cables. 188.
capacity of, 1085.
expenses of, 1087.
sixes of, 1086.
specifications for, 1083.
lines, hotel, 1088.
house, 1088.
private, 1088.
transposition of, 285.
znethod, meas. mutual ind. by,
68.
meas. self-induction by, 66.
X>lant, cost of. 1108.
depreciation of, 1108.
receiver. Bell, 1070.
watch, 1070.
switchboards, common battery,
1098.
design of, 1089.
portable, 1141.
series multiple, 1092.
system, branch terminal, 1093.
bridging, 1093.
central battery, 1096.
central energy, 1096.
common battery, 1096.
Pupin, 1107.
radial. 1117.
Telephone ssrstam, three-wire, 1099.
transfer, 1094.
two-wire, 1101, 1120.
systema. automatic exchange,
1105.
bridging of, 1110.
common signalling battery.
1115.
f our- wire seleetive, 1103.
intercommunicating, 1114.
Newburgh, 1103.
selective, 1102.
series party, 1109.
step-by«tep, 1102.
transmission, 1070.
two-party selective, 1 102.
Telephonic transmission, limits of,
1107.
Telephones, field, 1140.
fortress, 1140.
navy, spec, for, 1206.
Telephony, duplex, 1106.
multiplex. 1106.
Telescope for galvanometer, 24.
Temperature ooef. of copper, 627.
of metals, 138.
correction, 619.
of electric arc, 581.
of fire, 1349.
of room during test, 507.
of transformer windings. 447.
or intensity ci heat, 1506.
rise in armatures, 349, 358.
in boosters, 814.
in cables, 210.
in commutator, 362.
in field coils, 352.
in generatorB, U. S. Navy, 1 158.
in magnet coils, 127.
in railway motors, 675.
in switchboard devices, 910.
in transformere, 491, 498.
in meas. of, 518.
test by rise of resistance, 379.
tests of dynamos, 378.
records of, 381.
variation of resistance with, 228.
Tensile strength of copper wire,
table of, 156.
of woods, 1316.
1590
INT>EX.
Tension and sag in wire spans, 218.
Terminal anchorage, 637.
Terminals for bonds, 774.
Test oar, diagram of, 709.
lamps. Navy standard, 1172.
plate, desor. of, 537.
▼oltage, meas. of, 517.
Testinc-board, Herrick's, 805.
batteries, chloride of silver type,
16.
capacity of cables, 325.
drop and resistance in trolley
lines, 798.
dynamo efficiency, Kapp's method,
387.
electric plants. 1283.
instruments, description of, 13.
integrating wattmeters, 1028.
joints of cables, 323.
large transformer, Q. E. method,
490.
rail bonds, 801.
service meteiB, 1015.
set, 8.K.G. hii^ voltage, 461.
storage batteries, 882.
submarine cables, 331.
transformers, 459, 482.
Ayrton A Sumpner*s method
of, 496.
data for, 495.
Tests of American woods, 1317.
of cables, dielectric, 332.
of cast iron columns, 1306.
of d3mamos and motors, 378.
of interurban cars, 722.
of R. C. wire, Underwriters', 161.
of street railway circuits, 798.
of synchronous motors, 399.
of various types of steam engines,
1439.
of, with voltmeter, 74.
Thallium, phys. and eleo. prop, of,
140.
Thawing water pipes by electricity,
1271.
power required for etc., 1531.
Theater run of high npeetl railway.
721.
Theory of polypha.se induction
motor, 42.').
Theory of storage batteries, 872.
of synchronous motor, 432.
Thermal conductivity of dielectrir
Bpeci6c, 234.
unit, British, 3.
Thermit rail welding, 778.
Theimometers, comparison of. 1.51
Third rail bonding. 778.
cost per mile of, 835.
insulators, 831.
location of, 830.
qualities of steel for, 822.
shoes, 832.
system, 821.
Thompson permeameter, use (
9w~"96.
Thomson elec. welding process. 12^
induction wattmeters. 1005.
polyphase induction wattmeter
1005.
' recording wattmeters, 998.
-Ryan dynamo, special windi
of, 351.
Thomson's method, res. of gal v. f
60.
testing cap. of cables by, 32.'
Three conductor cables, G. £. O
table of, 170.
loss of power in sheath ' •
293.
watts per foot lost in. 212.
paper ins. cables, table of. 17-
Three-phase alternators, E.M.F. •
404.
armature winding. 413.
cables, power carrying cap. of, 2.J
circuits, arrangement of. 291.
charging current per 1000 f< -
of. 253.
energy in, 405.
self induction in, 239.
delta connection armatures, 1- *
in, 408.
distribution railway system. S
feeder j^anel, equip. <^, 917.
generator panels,' 912.
induction motors, current takr
by, 297.
potential regulators, 469.
lines, balancing of. 287.
INDRX.
1591
"Tliree-phase lineu. capacity effect in,
249.
motora, raadins watts in, 398.
power, meas. of, 72.
transmiasion, transfbrmera for,
478.
rotary converter, 437.
panels, equip, of, 919. 924.
rotary transformere, armatures of,
441.
star connection armatures, loss in,
408.
station bus-bars, 933.
synchronous motor panels, equip.
of, 919.
sjrstem. balanced, 73^
protection by relays, 959.
systems, ratio of transformers in,
471.
to six-phase connections, 475.
transformer connections, 473.
transformers, 470.
transmission line, ind. react, of,
246.
wiring examples, 273.
Three voltmeter method, A.C. power
by. 71.
Three-wire battery system, 899.
booster sjrstem, diagram of, 902.
direct current ssrstem examples,
271.
Edison system, 355.
generator panel, equipmentof , 926.
telephone system, 1099.
street railway sjmtem, 807.
two-phase system, formula for,
270.
variable speed motor nyntwii, 354.
Throttling calorimeter. 1394.
Ties, bearing surface per, 618.
durability of, 619.
per mile per track, 618.
Time-oonstant, formula for. 239.
element mechanism, 958.
limit relays, 956. ^
relay, Westinghouse. 960.
I required for elec. welding, 1272.
I Tin. fusing effect of current on, 217.
I phys. and elec. prop, of, 140.
spec. res. of. 132.
Tin, temperature ooef. of, 133.
Tire welding, electric, 1272.
Tires, data on, 1225.
Tirrell r^^lator for alternators, 400.
Toluene, spec. ind. cap. of, 37.
Toob and supplies for installing
electric work, 1530.
Toothed armatures, advantages of,
341.
Torpedo circuit closer, 1139.
firing, electric, 1213.
Torque of induction motors, oalc. of,
399.
of motor armatures, 353.
of polyphase induction motor, 423.
of railway motors, 731.
Torsion dynamometer, 42.
Tower, cooling, 1447.
Track and trolley, resistance of. 798.
bonding, condition of, 800.
bonds, efficiency of, 781.
requirements for, 775.
data, 618.
gang, tools for, 620.
laying force, 619.
rail, resistance of, 779.
return circuit, 771, 786.
Traction data, 1224.
horse-power (rf, 653.
law of. 110.
method, determ. magn. values by,
93.
oi electromagnets, 110.
table of. 111.
table of, 655.
Tractive coefficient, 662.
effort, 664.
curves of railway motors, 686.
of solenoids, 130.
on grades, 657.
test for, 1226.
force, table of, 654.
Train diagram, 787.
friction, 613.
curve, 679.
log for interurban tests, 722.
performance diagram, 663, 667.
resistance curve for one car train,
683.
voltage drop at,795.
1592
INDEX.
Tmining gear for gum. 1191.
Transfer telephone system. 1094.
adv. of, 1094.
Transformer cells for hydro-electric
plant, 931.
connections, 472.
cores, magnetic densities for, 447.
tests, data for, 495.
def. of. 503.
design, 447.
equations, 446.
house, single-phase A.C.. views of.
943.
loss. meas. of, 510.
oil, specifications for. 500.
panels, constant current, equip.
of. 922.
static, def. of, 443.
testing, 482.
TransformefB, ageing of. 498.
aiivblast type, 449.
capacity of, table of, 498.
change c^ hysteresis by heating in,
457.
characteristics of, 483.
comparative core losses in, 455.
oomparative expense of operating
large and small, 458.
connected to rotaiy converters,
442, 476.
connections for "wiring, 297.
copper loss in, table of, 498.
core loss in, 445.
table of. 498.
cores of American types of. 443.
current, descr. of, 945.
det. of size of, 295.
duties of perfect. 445.
efficiency of, 453.
test of. 493.
exciting current in, table of. 498.
for constant current. 464.
for constant secondary current,
462.
for long distance transmission.
arrangement of. 474.
for stepping-down high potential,
478.
for transmission plants, 870.
heat test of. 489. 497.
Transformers, hs^teraris loss of, 445k
improvement in, 4^.
insulation of, 447.
insulation test of, 483, ^16.
in three-phaae system, ratio *£.
471.
iron loss for. table of. 482.
leakage drop in, meas. of, 497.
location of. 499.
natural draft type, 448.
oU-oooled, 448.
polarity of, 495.
potential, descr. of. 945.
power factor of, 458.
protection by static intemipier of.
993.
regulation of, 458, 491.
table of, 498.
resistance of, meas. of, 486.
rise of temperature in, 498.
series type, 464.
specifications for. 498.
table of capacities of, 296.
temperature of windings of, 447.
temperature rise in, 520.
testing, 459.
testing iron and copper losses of,
496.
three-phase type, 470.
water-cooled type, 449.
wiring for, 295.
Y or delta connection of, 478.
Translating devices, distribution to,
262.
Transmission circuits, Ci^pacitj of.
249.
properties of, 238.
conductors for high tension, 235.
line formulae, 275.
inductive react, of three-phase.
245.
of known constants. 274.
Hoes, aluminum for high ten-ticw,
199.
calculation of. 264.
circuit breakers protecting. 951.
design of, 866.
efficiency of, 512.
high potential strains on, 981.
regulation of. 513.
INDEX.
1593
Tnuwmiasion of power, clttasif. of,
804.
of speech. 1070.
plants, switchboardfl for. 870.
system, oondueton for, 260.
telephonic, limits of, 1107.
Transmitters, battery, 1071 .
Blake, 1072.
granular button, 1074.
high-power. 1063.
magneto, 1071.
multi-contact, 1072.
sins^e-oontact, 1071.
BoUd back. 1072.
ungrounded, 1063.
'wireless telegraph, 1062.
Transmitting appliances, table of,
864.
Transposition of lines, 285.
telephone lines, 1082.
Transverse strength of beams,* 1308.
of woods, 1317.
Traversing motor for gun operation,
1134.
Trenton beams and channels. 1313.
iron beams and channels, 1314.
rolled steel beams, 1313.
Trial armature coil slots, 372.
values for number of armature
coils, 373.
Trigg works, motors, horse-power of,
1518.
Trimming arc lamps, 583.
Trip contact for relays, 958.
Triple oond. varnished cambric
cables, 185.
Triplex armature windings, 34>S.
Trip oil switches, use of. 916.
Tripping mechanism, 958.
Trolley and track, resistance of, 798.
cars, energy consumption of. 652.
power required for. 656.
wiring of, 806.
construction, cost of one mile of,
629.
for A.C. railways, 640.
feeders, arrangement of, 780.
line, drop at end of, 800.
material per mile of, 643.
system, laying out, 785.
Trolley and track, wheels. R.P.M. of.
655.
wire, dip in. 635.
sixe of. 786.
suspension. 637.
Troubles of storage batteries, 881.
Troy measure, 1500.
Truck lights. U.S. Navy. 1181.
Trucks of cars, weight of, 734.
Trunking, methods of, 1095.
Trunk signab, auxiliary, 1096.
Truss plank heaters, wiring diag. of.
1267.
Tube lighting system, 565.
Tubes, collapsing pressure of, 1429.
dimensions of boiler, 1428.
heating surface of, 1328.
regenerative X-ray, 1251.
X-ray, 1249.
Tubular lamps, navy spec, for, 1173
poles, iron and steel, 633.
Tungsten lamps, data on, 553.
steel, phys. and elec. prop, of,
140.
Turbines, dimensions of hydraulic,
1477.
dimensions of Victor. 1477.
impulse wheels, diagram of, 1479.
installing hydraulic. 1477.
inward flow of, 1476.
MeCormack, 4iMnim of, 1478.
outward flow of. 1476.
parallel flow, 1476.
steam, 1451.
U. S. Navy spec, for steam, 1160.
water, 1476.
Turbo generating sets, spec, for, 1 159.
generators, operation of, 1162.
Turnout suspension. 638.
Turnouts, railway, 620.
Turns of wire for transformers,
equation for, 446.
of wire in coil. ealo. of. 113.
per armature coil, trial calc. for,
374.
Turpentine oil, spec. ind. cap. of,
37, 227.
Turret turning gear, navy spec, for,
1187.
sjrstem, 1165.
1594
INDEX.
Twin conductor wire table, U. S.
Navy, 1170.
Twisted pain, use of, 1082.
wire, res. betw. terminals of, 86.
Two-circuit single winding of arma*
ture, 342.
-conductor cables, watts per
foot lost in, 212.
motors vs. four motors per car,
720.
overhead wires, capacity of, 250.
-party selective telephone sys-
tems, 1102.
-path triplex armature winding.
348.
-phase armatures, loss in, 408.
armature windings, 412.
circuits, arrangement of, 201 .
feeder panel, equip, of. 918.
generator panel, 915.
rotary converter, 436.
rotary converter panels, 921.
rotary transformers, armatures
of, 441.
systems, formula for, 270.
transformer connections, 472.
transmission circuit, calc.of,280.
wiring examples, 272.
Two-wire direct current sj^stem
examples, 271.
telephone system, 1101. 1120.
Types of plates for batteries, 874.
of underground cables, 320.
oscillations, 1068.
Underground and submarine cables,
tests of, 321.
cables, drawing in, 319.
locating faults in, 331.
types of, 320.
conduits and construction, 301.
in Chicago, cost of, 317.
mains, current variations on, 857.
metal, deterioration of, 852.
telephone cables, 188.
capacity of, 1086.
work at New Orleans, 808.
Underload circuit breakers, 050.
use of. 899.
D.C. relay, 962.
Underwriters' rules for ptoteetioQ <tf
buildinsB. 1280.
test of R. C. wire, 161.
Ungrounded transmitten, 1063.
Uniform railway oondoetofs, 702.
Unipolar machines, def . of, 50L
losses in, mess. of. 511.
Uni Signal Company system. 624.
Unit difference of potential, 4.
dectro magnetic definition of. -5
electro-motive force, 4.
lightning arrester, 990.
of capacity. 4.
of current, 4.
of force, 3.
of horM-power, 3.
of quantity. 4.
of resistance, 4.
of resistance, definition of. 5.
of strength of pole. 4.
of work, 3.
switch control, A.C. railway
system, 710.
system, 76^.
wei^ts, 1513.
United States Army, une of elee. in.
1123.
Navy electric fuse, 1137.
electricity, in 1153.
engine spedficationa for,
1154.
generator spec, for, 1156.
Units, absolute, 2.
C. G. S., 2.
derived geometric, 2.
derived mechanical. 2.
electrical, 4.
and mechanical, table of. 135S.
engineering, 2.
electrostatic, 4.
fundamental, 2.
geometric, 2.
international electrical. 9.
magnetic, d^nition of, 4.
of heat. 3.
of Ught. 530. 534.
of resistance. 131.
symbols and abbreviations for, 6.
Universal shunt, Ayrton and Mather.
30.
INDEX.
1595
Unstable neutral, 479.
Upper harmonios, theory of, 1218.
Uses of incandescent lamps, 544,
555.
of Ught, 600.
of storage batteries, 886.
U. S. Navy rule for ins. res., 85.
standard lamps, table of, 1176.
U.S. standard gauge for sheet and
plate steel and iron, 1299.
sheet metal gauge, thickness in
millimeters, 1299.
Utensils, electric cooking, cost of
operating, 1259.
^'acwvbi, spec. ind. cap. of, 35.
tube light. 565.
tubes, exciting source for, 1252.
Value of A.C. voltage and current in
terms of D.C., 438.
Values for numbers of armature
coils, 373.
for turns per armature coil, 374.
Valve, foot. 1447.
Vapor lamps, Cooper-Hewitt type,
558.
Vapors, specific gravity of, 1512.
Variable speed motor work. 354.
Variation, def. of, 505.
of efficiency of lamps, 547.
of resistance with temperature.
228.
of voltage in storage battery, 876.
Varley loop test, locating faults in
cables by, 329.
Varnished cambric ins. cables, tables
of. 179-183.
triple cond.. 185.
Vaseline, spec. ind. cap. of, 37.
Vegetable oils, 1497.
Velocity, angular, 1505.
definition of, 3.
definition of, 2.
Ventilation fans, navy spec, for,
1196.
of armatures, 350.
of transformers, 449.
Vertical shear of beams, 1308.
tubular boilers. 1327.
Very high res., meas. of, 79.
Victor turbines, dimensions of, 1477.
Virtual resistance of storage cell.
883.
Voltage and current of A.C. in terms
of D.C.. 438.
curve of railway motors, 669.
curves of storage batteries. 883.
drop at brush faces, 362.
in parallel distribution system,
279.
in storage cells, table of. 879.
for power transmission, 870.
limitation of, 866.
loss in storage batteries, 882.
meas. of, 62.
regulation of transformers, 452.
transformers, high-tension station,
938.
variation in storage battery, 876.
variations, minimising, 1002.
Voltages, discussion of standard.
522.
for plating. 1234.
Voltaic battery, def. of, 14.
, Voltameter, silver, description of, 10.
Volt, definition of, 5.
generation of. 336.
international, def. of, 9.
specification for determ., 10.
value of, 7, 8.
Voltmeter, balance used as, 43
Bristol recording single-phase,
1038.
electrostatic, Kelvin. 40.
method, meas. of current by, 77.
Weston type. 41.
Voltmeters, description of, 40.
electrostatic, use of. 945.
high res. for. 75.
meas. high res. with, 79.
ins. res. of circuits with, 80.
ins. res. of wiring system with.
82.
res. with, 78.
permanent magnet type, 74.
tests with, 74.
Voltex process for welding and
brasing, 1274.
Volume of steam, tables of, 1404.
Voynow joint, 778
1596
INDEX.
Vulcanized rubber, electrical prop>
erties of, 229.
ler motor, design of, 430.
single-phase motor, connections
of, 431.
Walmsley's rail tester, 802.
Ward-Leonard system of motor
control, 354.
turret turning gear, 1188.
Waring cables, joints in, 191.
Warren's method, locating faults in
ins. wires by, 330.
Watch receiver, 1070.
Water analyses, table of, 13dd.
and mercury columns, premure of,
1403.
-cooled transformers, 449.
cubic feet discharged per min.,
1470.
expansion of, 1362.
flow, estimate of. 869.
in a stream, 1471.
over Weirs, 1473.
through an orifice, 1471.
through various pipes, 1469.
for boiler feed, 1362.
friction in pipes of, 1374.
gas 1357.
heating by electricity, cont of,
1259.
horse-power, tables of, 1476,
lifted by suction, 1367,
loss of head due to bends in pipen,
1374,
mains, effect of current on, 852.
meters, electrolytic effect on, 858.
motors, regulation of, 514.
pipes, thawing out, 1271.
power, 1460.
data on, 867.
synopsis of report on, 1460.
yearly expense per H.P. of, 1464.
pressure of, 1465.
pimiping hot, 1367.
purification of boiler feed by
boiling. 1365.
rheostats, 33.
rod float gauging, 1471.
specific heat of, 1511.
Water, specific inductive capaeity of,
227.
res. of, 133.
speed througih pump-paasages ai^
valves of, 1368.
theoretical velocity and discbarse
of. 1470.
tight door alarm, U. S. Natj,
1211.
doors, control of. 1198.
weight per cubic foot of, 13410.
wheels. 1476.
racing of, 981.
Watt, definition of, 3.
-eecond, value of, 12.
value of, 5. 8.
Wattless current, def. of. 298.
Wattmeter, balance uaed a^, 44.
hysteresis tested by, 102.
power meas. by, 72.
Wattmeters, action of, 1039.
bearines of, 1009.
Bristol recording ainsle-pfaaw,
1087.
calibration of. 1014.
Westinghouse intecratins, 1016.
checking, 72.
constants of. 1029.
D. C. Sangamo, 1007.
Fort Wayne induction, 1005.
testing of. 1083.
G. E. recording, 1030.
testing of, 1030.
integrating, testing of. 1013.
on inductive circuit, 1000.
polyphaae and D.C., testing of,
1020.
installation of, 1023.
integrating, 1004.
prepayment, 1010.
Sangamo integrating, 1006.
testing of, 1035.
speed error table for, 1032.
speeds of, 1029.
Thomson hi|^ torque, 1005.
polyphase indaction, 1005.
recording, 998.
use of, 72.
Westinj^oose induction. 998,
1008.
1
INDEX.
1697
^Tttttmeter, Westioghouae raoordins,
1037.
Weston type, 42.
Wright discount. 1008.
^^atts lost in armature cores, 360.
in annature windings, 359.
in cables, 210.
in core of transformer, 456.
transformer cores, 454.
per candle of arc lamps, 540.
MTave-eonnected annature wind-
ings, 347.
form, determination of, 49.
E.M.F., 1218.
shape, definition of, 508.
Waves, electromagnetic, 1055.
propagation of, 1058.
Wax, specific inductive capacity of,
227.
Weathei>proof aluminum wire
stranded, 197.
wire, carrying capacity of, 209.
table of, 160.
Weaver speed recorder, 1212.
Webb, H. S. on water rheostats, 33.
Weber photometer, 537.
Wehnelt interrupters, 1254.
Weight and bulk of bricks, 1322.
of A.C. motor equipments, 719.
of aluminum, 1514.
of brass, sheet and bar. 1323.
of car bodies and trucks, 734.
of chains, 1496.
of conductors, calo. of, 277.
formula for, 265.
table of, 270.
of copper, 143.
and brass wire and plates, 1324.
per K.W. del'd, curves show-
ing, 283.
round bolt, 1323.
wire, English system, table of,
157.
metric system, table of, 158.
of flat iron, 1295.
of iron and steel, 1294.
per sq. ft. in kilograms, 1299.
per sq. ft. in lbs., 1299.
per sq. ft. in ounces, 1299.
per sq. meter in kilograms, 1299.
Weight of iron and steel per sq.
meter in lbs., 1299.
of oil per gallon, 1497.
of plate Iron, 1298.
of rails, 615.
of railway equipments, 789.
of square and round iron, 1297.
of steam« tables of, 1404.
of storage cells, 882.
of various woods, 1316.
cf water per cubic foot, 1360.
above 212° F., 1361.
of wood, 634.
per mile-ohm, def . of, 131.
Weights and measures, 1499.
apothecaries, 1600.
avoirdupois, 1500.
metrical equivalents. 1501.
troy, 1500.
Weiny-Phillips repeater. 1043.
Weir dam measurement, 1473.
table, 1474.
Weirs, Francis' formuln for, 1474
Welding, electric, 1271.
H.P. used in electric, 1271.
iron pipe, 1272.
tiies, 1272.
Western Electric telephone system,
U. 8. Navy. 1207.
Westinghouse A.C. motor charaoter-
istios, 715.
A.C. railway system, 707.
circuit breaker, 951.
economy coil, 463.
electromagnetic railway, 841.
generator panel, 925.
induction type wattmeters, 999,
1003.
integrating meters, 998.
locomotives, 744.
method of balancing magnetic
circ. in dynamo, 349.
mercury arc rectifiers, 481.
oil circuit breakers, 969.
railway motors, 729.
characteristic curves of, 696.
rating of, 678.
recording meters, 1087.
relay, D. C. over-voltage, 962.
rotary panel, 925.
1598
INDEX.
Westinghouse single-phase potential
regulators, 467.
switchboard panel, 907.
three-wire generator panel, equip-
ment of, 926.
unit switch control system, 766.
wattmeters, calibration data for,
1016.
test formula for, 1028.
Weston cadmium cell, 19.
model, Wheatstone bridge, 56.
voltmeter, 41.
wattmeter, 42.
Wheatstone bridge, 32.
Y-box multiplier, 73.
Wheatstone bridge, description of,
31.
Kelvin type, 59.
method, res. meas. by, 56.
method, E.M.F. of batteries, 62.
Wheels, R.P.M. of trolley, 655.
Whistle, electric, navy spec, for,
1210.
White core ins. three cond. cable,
table of, 170.
Winches, deck. 1196.
Windage test for dynamos and
motors, 383.
Winding of eleotromagnetj«, 112.
field-magnets. 369.
plunger solenoids, 128.
ring armature, 342.
Windings of A.C. armatures. 410.
Wind velocity on wire spans, effect
of. 219.
Wire, aluminum, deflection in feet of,
226.
properties of, 194.
resistance of stranded, table of,
198.
galv. iron, water rheostats, 34.
gauge, U. S.. and wei^^ts of iron,
1299.
gauges, table of, 141.
magnet, table of, res. of, 112.
rope, galvanised iron, 1325.
notes on uses of. 1494.
standard hoisting, 1326.
transmission of power by,
1495.
Wire, transmission or haulsise bj.
1325.
ropes, horse-power of, 1485.
sises for armature eoila, 372.
solid copper, table of, 154.
spans, tension and sag in, 218>
steel, properties of. 201.
stranded copper, table c^, 155.
strands, table of. 142.
table, U. 8. Navy. 1169.
tables, copper, AJJBJB.. 146.
explan. of, 145.
weight of copper, table of, 1.57.
Wireless tdegraphy receivers, 1064.
theory of, 1055.
transmitters, 1062.
U. S. Army. 1145.
Wires and cables, properties of,
131.
current carrying capacity of. 206.
fusing effect of current on, 217.
gutta-percha coveted, jointing off,
193.
navy standard, table of, 174.
paper ins. G. E. tables of. 174-178.
rubber ins. G. E. tables of, 164-
172.
space occupied by cotton ooirered,
tables of. 121-126.
d. c. cov., tables of, 123-126.
s. c. GOV., tables of. 121-123.
U. 8. Navy spec, for, 1167.
suspended from points not ia
same levd, sag in, 223.
Wiring bells, 203.
diagrams of ears, 806.
for transformers, 295.
of can, 746.
for heaters, diagram of. 1267.
of hohses, 279.
plans, standard ssrmbob for, 290
specifications, U. 8. Navy, 1167.
system, ins. res. of, 82.
Wood as fuel, 1356.
b^ms, strmgth of. 1318.
mill, power required to run toob
for, 1519.
specific inductive capacity of, 227
tests of American, 1317.
weight per cord of, 1356.
INDEX.
1599
Wood working maehinery, power to
run. 1519.
tools, power required for, 1522.
Wooden poles, contents d, 033.
pchinting of, 806.
stove pipe, 1468.
Woods, American, wt. and value as
fuel of, 1349.
erushins strengths of. 1316.
pressure to indent A", 1316.
properties of various, 1316.
relative strength for cross break-
ing. 1316. *
shearing strength with the grain of,
1316.
specific gravity, table of. 1512.
tensile strength of, 1316.
value in tons of coal, 1349.
-weight of, 634.
per cubic foot of, 1316.
per ft. B. M., 1316.
Woolf process, disinfecting by, 1244.
Work done by conductors in magn.
field. 109.
international unit of, 10.
unit of, 3.
unite compared wfth energy units,
12.
Workshop method, res. of batteries,
61.
Wright demand meter, 1008.
discount meter, 1008.
Wrought iron, permeability of, 89.
phys. and elec. prop, of, 137.
pipe, dimensions of, 1426.
poles, weight of, 633.
qualities of, 824.
Wurts lightning arresters, 984.
X-rays, polarisation of, 1248.
theory of, 1248.
tubes for, 1249.
Xylene, spec. ind. cap. of, 37.
Y-box multiplier. Weston, 73.
-connection of transformers, 478.
Yokes, field magnet, general data on,
352.
Z«rea«r system of welding, 1274,
Zero instrument, Northrup, 26.
Zinc amalgam for standard cell,
11.
for boiler scale, 1365.
phys. and elec. prop, of, 136, 140.
spec. res. of, 132.
sulphate for standard cell, 11.
spec. res. of, 133.
temperature coef . of. 133.
Zone, oommutating, 350.
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