The performance and design of direct current machines.

By: Clayton, Albert Edmund, 1886- [from old catalog]Material type: TextTextPublication details: New Delhi : CBS, 1986cEdition: 3d edDescription: 516 p. illus. 23 cmISBN: 9788123909276 (pbk)Subject(s): Electric machinery -- Direct current. [from old catalog]DDC classification: 621.3132 LOC classification: TK2612 | .C6 1959
Contents:
CHAPTER I GENERATION OF E.M.F. : WORK; POWER; TORQUE 1 Homopolar machine — Heieropolar machme--K.m.f. induced in d.o. machine — Wave shape of induced e.m.f. — Flux distribution curve and frmging — Average value of induced e.m.f. — Dir(»ctJon of induced e.m.f. — Force on conductor carrying current —Power developed by armature — Torque develo{>ed by armature. CHAPTER II MAGNETIC CIRCUIT OF THE DIRECT CURRENT MACHINE 14 The laws of the magnetic circuit — Unite-- Relative peimeabiht \ - Magnetization curves for iron — Magnetic circuit of d.o. machine - Flux distribution curve or field form— R<ductanco of the air j^ap - Active iron length —Armature teeth — TajM^rtni teeth — Ktial and apparent flux density — Armature cor© — Polo shoos Form of fH>le section— Magnetic leakage — Effect of load upon leakage cmdTicient —The yoke — Magnetization curve of dr. machine - Kffect of saturation upon field form — Field form and voltage between commutator segmenta— Flux plotting CHAPTER JII ARMATURE WINDINGS ....... 53 Drum windings — Two layer windings— Coil span —Wind uig pitch — Commutator pitch — Numberuig armature conduct/ora— Suiiple lap winding — Equalizing rings — Choice ot numb(*r of slots for lap windings — Simple wave or series wmding — CTioico of number of slots for wave windings- -Dununy coils — Brusli sets and brush position for simple wave winding — Voltage between adjacent segments — Multiplex windings — Duplex lap windings— £^uabzing connetciona to duplex lap windings — Duplex wave windings — Triplex wmdinge CHAPTER IV ARBfATURE REACTION 90 Magnetizing action of anmature currents — m.mY. eatabliahed by a fulbpitched drum coil — Flux distribution due to annatura curreata — Armature reaction and flux distribution curve — Effsot of brush lead— Effect of saturation upon flux distribotkMi — Domagnetisii^ and cro« xnagnatiz^ ampm*tunis — Armatuxe reaction and iron losses — Comfiensating windings. 1 CONTENTS CHAPTER V GROWTH 07 OURBBMT IK A GZBOUTT; XROK LOSSES Inductance — Growth of a d.c. — Decay of current in a closed circuit — Reversal of a d.c. — Energy of the magnetic field — Magnetic pull between poles and armature — Magnetic hysteresis — Eddy current loss — Total iron loss curves — Iron losses in d.c. machines. CHAPTER VI COMMUTATION brush contact resistance — Current density — E.m.f. induced ir coil undergoing commutation — Time of commutation — Slot permeance — {..eakage ac:ro88 tooth tips — Inductance of end connexions — Total inductance — Reactance e.m.f. — Commutation in non- interpole machines — Interpoles — Calculation of flux density — Calculation of ampere-turns for mterpole windings — Interpole shoo width — Magnetic leakage with mterpole machines — Com- mutation with bar windings — Interpole ampere-tums with com- {x^nsating windings. CHAPTER VII EXCITATION AND FIELD WINDINGS ..... Separate excitation — Self excitation — Shunt generator — Effect of speed upon self excitation — Failure to excite — Reversed polarity — ^ries generator — Compound-Wound generator — Field windings - Calculation of shunt coils — Calculation of series coils. CHAPTER VIII LOAD CHARACTERISTICS OF DIBECT CURRENT GENERATORS . External characteristic of separately excited and shunt generator — Series generator characteristic — Compound generator char- acteristic — Generators m parallel — Equalizing connexion. CHAPTER IX LOAD CHARACTERISTICS OF DIBECT CURRENT MOTORS . Hack e.m.f. induced m motor armature — Load characteristics ot shunt, senes, and compound motors— Speed voltage character- istics of motom — Parallel operation — Series operation. CHAPTER X CONTROL OP DIRECT CURRENT MOTORS Constant voltage and variable field — Variation of voitage applied to armature — Ward-Leonard control — Use of variable voltage booster — Motors on rectifier supplies — Starting torque and acceleration — Grading of starting resistances — Graphical con- struction — Energy dissipated in rheostats — Economy of series- parallel starting — Drum end contactor controllers — Automatic accelerat ion — Electric braking. PAOI 106 131 163 180 197 207 CONTENTS xi CHAPTER XI PAOl EFnCIENCY— TEMPERATURE RISE— VENTILATION . . . 242 Iron loaaes — Electrical losses — Mechanical loases — Efticiericy curve Maximum efficiency — Maximum output — TemjHjraiure rise— Tempierature curve— Rating of electrical mat'hmery— Prede- termination of temperature rise— Ventilation — Totally enclosed machines. CHAPTER XII ITINO 2&2 Brake tests — Swinburne's method of compiiimg efficiency-' Differential tests— Hopkmson tests — Temperature tests -Sefiara- tpon of iron and friction loss —Separation of hystt^resis anti ctldy current losses— Torque wastetl in iron losses - Ueiardation test- rommutation tests - Armature laultn. CHAITER SPECIAL MACHINES 296 Shunt, or separately -excited Ijooster — Senes boosters for irat lion work— Buffer batteries-' Battery boosters - Shunt woimd exciu*r - -The D>Tiamotor — Balancers - Special character istics- - I'hree held (Kramer) generator— Austin constant curren! generator *- Welding generators —Two-stage machines— Cross-field rnat'hiiies - The inetadync generator— Amplidyne - Magnicon -Metadyne converter — Consequent-pole rnachint'S --Motors for coimlnut- current systems — Split-held motors. CHAPTER XIV insulation — ARMATURE AND FIELD COILS . . .331 Cla.S'tdication - Varnishes and ensunels Insulateri wires- Ta|>es - Flexible sheet materials — Boards — V^arnish treatment —Armature coils - Thicknea'i of insulation — Field windings —Space factor. CHAPTER XV MECHANICAL DETAILS 355 Magnet system— Main polos — Interpoiea — Armature — Commu- tator — Brushes — Brush hoKlors — Angle between ‘brush and com- mutator— Staggering of brushes — ^The shaft — Bearings — Traction motors — Industrial motors - Mill moton. i CONTENTS CHAPTER XVI BSIQN CONSIDXBATIONS 391 Fiindament-al output relations — Flux density in the air gap— Armature strength or specific electric loading — Esson output coefficient — Variation in output coefficient with dimensions — Number of poles — Pole pitch-^ore length — Armature diameter — Ratio pole arc to pole pitch. CHAPTER XVII SSION OF D.c. generator; main dimensions; armature 405 Preliminary determinations — Main dimensions, number of poles being given — Design of armature stampings and winding — Mean e.m.f. induced per conductor — Number of conductors m series on the armature — Number of slots — Dimensions of armature conductor — Slot design — C!ore length final dimensions — Depth of armature core — Armature winding — Equalizing connexions — Armature conductor length — Overhang of the winding — Weight of copper — Resistance of winding. CHAPTER XVIII )Esiqn ; the field system 424 The field magnet— Polo sectional area — Pole height— The yoke- - The air gap — Magnetization curve — Iron losses— Armature tem- perature rise— Commutator design— Brushes— Field winding design— Interpole design — Bearmg friction and windage — Total losses and efficiency. CHAPTER XIX further EXABiFLES OF DESIGN OF MOTORS AND OBNEBATOKS 445 Other designs based on a given 1,000 kW generator — Design based on output per pole — Physical limits to d.c. machines — Design of motors — Examples of choice of armature windings — Design data for various generators and motors. CHAPTER XX EDDY CURRENT LOSSES IN ARMATURE CONDUCTORS . 473 Eddy current losses with sinusoidal currents — Eddy current losses in d.c. armature conductors — Variation of t<jtal losses with conductor depth.
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Books Books Namal Library
Electrical Engineering
621.3132 CLA-P 1986 4384 (Browse shelf (Opens below)) Available 0004384
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Index present

CHAPTER I

GENERATION OF E.M.F. : WORK; POWER; TORQUE 1


Homopolar machine — Heieropolar machme--K.m.f. induced in
d.o. machine — Wave shape of induced e.m.f. — Flux distribution
curve and frmging — Average value of induced e.m.f. — Dir(»ctJon
of induced e.m.f. — Force on conductor carrying current —Power
developed by armature — Torque develo{>ed by armature.

CHAPTER II

MAGNETIC CIRCUIT OF THE DIRECT CURRENT MACHINE 14

The laws of the magnetic circuit — Unite-- Relative peimeabiht \ -
Magnetization curves for iron — Magnetic circuit of d.o. machine -
Flux distribution curve or field form— R<ductanco of the air j^ap -
Active iron length —Armature teeth — TajM^rtni teeth — Ktial and
apparent flux density — Armature cor© — Polo shoos Form of fH>le
section— Magnetic leakage — Effect of load upon leakage cmdTicient
—The yoke — Magnetization curve of dr. machine - Kffect of
saturation upon field form — Field form and voltage between
commutator segmenta— Flux plotting

CHAPTER JII

ARMATURE WINDINGS ....... 53

Drum windings — Two layer windings— Coil span —Wind uig pitch
— Commutator pitch — Numberuig armature conduct/ora— Suiiple
lap winding — Equalizing rings — Choice ot numb(*r of slots for lap
windings — Simple wave or series wmding — CTioico of number of
slots for wave windings- -Dununy coils — Brusli sets and brush
position for simple wave winding — Voltage between adjacent
segments — Multiplex windings — Duplex lap windings— £^uabzing
connetciona to duplex lap windings — Duplex wave windings —
Triplex wmdinge

CHAPTER IV

ARBfATURE REACTION 90

Magnetizing action of anmature currents — m.mY. eatabliahed by
a fulbpitched drum coil — Flux distribution due to annatura
curreata — Armature reaction and flux distribution curve — Effsot
of brush lead— Effect of saturation upon flux distribotkMi —
Domagnetisii^ and cro« xnagnatiz^ ampm*tunis — Armatuxe
reaction and iron losses — Comfiensating windings.



1 CONTENTS

CHAPTER V

GROWTH 07 OURBBMT IK A GZBOUTT; XROK LOSSES

Inductance — Growth of a d.c. — Decay of current in a closed circuit
— Reversal of a d.c. — Energy of the magnetic field — Magnetic pull
between poles and armature — Magnetic hysteresis — Eddy current
loss — Total iron loss curves — Iron losses in d.c. machines.


CHAPTER VI


COMMUTATION

brush contact resistance — Current density — E.m.f. induced ir coil
undergoing commutation — Time of commutation — Slot permeance
— {..eakage ac:ro88 tooth tips — Inductance of end connexions —
Total inductance — Reactance e.m.f. — Commutation in non-
interpole machines — Interpoles — Calculation of flux density —
Calculation of ampere-turns for mterpole windings — Interpole
shoo width — Magnetic leakage with mterpole machines — Com-
mutation with bar windings — Interpole ampere-tums with com-
{x^nsating windings.


CHAPTER VII

EXCITATION AND FIELD WINDINGS .....

Separate excitation — Self excitation — Shunt generator — Effect of
speed upon self excitation — Failure to excite — Reversed polarity —
^ries generator — Compound-Wound generator — Field windings
- Calculation of shunt coils — Calculation of series coils.


CHAPTER VIII

LOAD CHARACTERISTICS OF DIBECT CURRENT GENERATORS .

External characteristic of separately excited and shunt generator
— Series generator characteristic — Compound generator char-
acteristic — Generators m parallel — Equalizing connexion.


CHAPTER IX

LOAD CHARACTERISTICS OF DIBECT CURRENT MOTORS .

Hack e.m.f. induced m motor armature — Load characteristics
ot shunt, senes, and compound motors— Speed voltage character-
istics of motom — Parallel operation — Series operation.


CHAPTER X

CONTROL OP DIRECT CURRENT MOTORS

Constant voltage and variable field — Variation of voitage applied
to armature — Ward-Leonard control — Use of variable voltage
booster — Motors on rectifier supplies — Starting torque and
acceleration — Grading of starting resistances — Graphical con-
struction — Energy dissipated in rheostats — Economy of series-
parallel starting — Drum end contactor controllers — Automatic
accelerat ion — Electric braking.


PAOI

106


131


163


180


197


207



CONTENTS xi

CHAPTER XI

PAOl

EFnCIENCY— TEMPERATURE RISE— VENTILATION . . . 242

Iron loaaes — Electrical losses — Mechanical loases — Efticiericy curve
Maximum efficiency — Maximum output — TemjHjraiure rise—
Tempierature curve— Rating of electrical mat'hmery— Prede-
termination of temperature rise— Ventilation — Totally enclosed
machines.


CHAPTER XII


ITINO 2&2

Brake tests — Swinburne's method of compiiimg efficiency-'
Differential tests— Hopkmson tests — Temperature tests -Sefiara-
tpon of iron and friction loss —Separation of hystt^resis anti ctldy
current losses— Torque wastetl in iron losses - Ueiardation test-
rommutation tests - Armature laultn.


CHAITER


SPECIAL MACHINES 296

Shunt, or separately -excited Ijooster — Senes boosters for irat lion
work— Buffer batteries-' Battery boosters - Shunt woimd exciu*r
- -The D>Tiamotor — Balancers - Special character istics- - I'hree
held (Kramer) generator— Austin constant curren! generator *-
Welding generators —Two-stage machines— Cross-field rnat'hiiies -
The inetadync generator— Amplidyne - Magnicon -Metadyne
converter — Consequent-pole rnachint'S --Motors for coimlnut-
current systems — Split-held motors.


CHAPTER XIV

insulation — ARMATURE AND FIELD COILS . . .331

Cla.S'tdication - Varnishes and ensunels Insulateri wires- Ta|>es -
Flexible sheet materials — Boards — V^arnish treatment —Armature
coils - Thicknea'i of insulation — Field windings —Space factor.


CHAPTER XV


MECHANICAL DETAILS 355

Magnet system— Main polos — Interpoiea — Armature — Commu-
tator — Brushes — Brush hoKlors — Angle between ‘brush and com-
mutator— Staggering of brushes — ^The shaft — Bearings — Traction
motors — Industrial motors - Mill moton.



i


CONTENTS
CHAPTER XVI

BSIQN CONSIDXBATIONS 391

Fiindament-al output relations — Flux density in the air gap—
Armature strength or specific electric loading — Esson output
coefficient — Variation in output coefficient with dimensions —
Number of poles — Pole pitch-^ore length — Armature diameter —

Ratio pole arc to pole pitch.


CHAPTER XVII

SSION OF D.c. generator; main dimensions; armature 405

Preliminary determinations — Main dimensions, number of poles
being given — Design of armature stampings and winding —

Mean e.m.f. induced per conductor — Number of conductors m
series on the armature — Number of slots — Dimensions of armature
conductor — Slot design — C!ore length final dimensions — Depth of
armature core — Armature winding — Equalizing connexions —
Armature conductor length — Overhang of the winding — Weight of
copper — Resistance of winding.


CHAPTER XVIII

)Esiqn ; the field system 424

The field magnet— Polo sectional area — Pole height— The yoke- -
The air gap — Magnetization curve — Iron losses— Armature tem-
perature rise— Commutator design— Brushes— Field winding
design— Interpole design — Bearmg friction and windage — Total
losses and efficiency.


CHAPTER XIX

further EXABiFLES OF DESIGN OF MOTORS AND OBNEBATOKS 445
Other designs based on a given 1,000 kW generator — Design based
on output per pole — Physical limits to d.c. machines — Design of
motors — Examples of choice of armature windings — Design data
for various generators and motors.


CHAPTER XX

EDDY CURRENT LOSSES IN ARMATURE CONDUCTORS . 473

Eddy current losses with sinusoidal currents — Eddy current losses
in d.c. armature conductors — Variation of t<jtal losses with
conductor depth.

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