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<<< < Предыдущая 12 / 432 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 > Следующая >>>

A large number of problems have been solved to help understand the theory. At the end of each chapter unsolved problems with their answers have been suggested for further prac tice. At the end, a large number of objective type questions have been added to help the reader to test himself.

Any constructive suggestion for the improvement of the book will be gratefully acknowledged.

Last but not the least, I with to express my gratitude to mywife Usha, daughter Meenu and son Sandeep for their patience and encouragement during the preparation of the book.

-C.L. Wadhwa

	CONTENTS
Preface to the Fourth Edition	....................................................................................... (vii)
Preface to the First Edition ...........................................................................................	(ix)

DC CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

i.1 i.2 i.3 i.4

i.5

i.6 i.7 i.8 i.9 i.10

International System of Units ...................................................................................				1
Circuit ..........................................................................................................................				3
Electric Current .			. .
Electric Potential ........................................................................................................				4
Resistance ...................................................................................................................				6
i.5.1	Conductivity and Conductance			3
i.5.1	Conductivity and Conductance	.	. .	7
Power				8
Energy .........................................................................................................................				8
Ohm's Law ................................................................................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . . .	. 8
Kirchhoffs Laws .......................................................................................................				11
Series Circuits ...........................................................................................................				13
i.10.1	Parallel Circuits .............................................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . . . .	15
i.10.2	Series. . . . . . . . . . . Parallel. . . . . . . . . . . . . . .Circuits. . . . . . . . . . . . . . ................................................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	. . . . . . . . . . . . . . .	. . . . . . . . . . . . . . . . . . . . .	18

ii	ELECTROMAGNETIC INDUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		29
	ii.1	Introduction ..............................................................................................................	29
	ii.2	Faraday's Laws of Electromagnetic Induction.......................................................	29
	ii.3	Lenz's Lavv.................................................................................................................	30
	ii.4	Laws of Electromagnetic Forces ..............................................................................	30
		ii.4.1 Fleming's Left Hand Rule .............................................................................	32
		ii.4.2 Flemings Right Hand Rule ...........................................................................	33
	ii.5	Dynamically Induced EMF (Generator or Motional EMF) ...................................	33
		ii.5.1 Statically Induced EMF or Transformer EMF............................................	34
	ii.6	Self Inductance .........................................................................................................	35
	ii.7	Mutual Inductance ...................................................................................................	36
	ii.8	Hysteresis Loss .........................................................................................................	38
	ii.9	Eddy Current Loss ...................................................................................................	40
1 A.C. ClRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			49
	1.1	Introduction ..............................................................................................................	49
	1.2	Phase .........................................................................................................................	51
	1.3	The Average Value of a Waveform ..........................................................................	52
	1.4	The Effective or RMS Value of a Wave ...................................................................	54

		1.4.1	Form Factor													xii																									55
	1.5	1.4.2	Peak Factor or Crest Factor																																						56
	1.5	Phasor Diagram .				.	.....		.				. . . . ... . . . . . . . ....... . . . . ...... . .																				. . . . . .. . . . . .								56
		1.5.1	Phasor Algebra																					Voltage .									. . . . . . . . . .								57
	1.6	Resistance Connected .Across. . . . . a.Sinusoidal. . . .																						Voltage .									. . . . . . . . . .								57
		1.6.11	Inductor Across Sinusoidal Source. . . . . . . . . . . .. . .. .. .. ..... . ..... .. . .... .. .. .. .. . .. . .. ..... . .. ..... . . ..																														. .... .... .. ... ... ... .... .... .... . ... ..... ... ...				.	.	..	.	60
																																									58
		1.6.2	Capacitor Connected. . . . . . . . . . . . . . . .Across. . . . . . . . . . .Sinusoidal. . . . . . . . . . . . . . . . . . . .Source. . . . . . . . . .																										. . . .	. . . .	. . .	.	. . . . . . .	... ... .. . . . . .. . ... . .	. . . .	. . ... ..					59
		.6.3 Series R-L Circuit Connected to Sinusoidal Source
	1.9	1.6.4	RC Series Circuit. . .									Connected. . . .							to. . Sinusoidal. . .									Source. . . .													61
	1.9	Series Resonance .... . .. . . . . .. . . ... . . . .... .. . . . . . . .... . ... ..																															. ... ... ... . . . . . . ..... . . . . . ... ..... . . ... ...								70
		1.6.5	R-L-C Series Circuit. . . . . . . . . . .Connected. . . . . . . . . . . . . . . .to. . . . .Sinusoidal. . . . . . . . . . . . . . . . . . Source. . . . . . . . . . . . .																													.	. . . . . . .	. . . . . . . . . . . . . . .	. . . .	.		.	.	.	64
	1.7	1.9.1	Quality Factor Q								.	.	....	. .	.	.				. .....					..... . . ... . . . .. . ... ....... . . . . ... ... ...... . . . ... ... ... ... .... . ...																74
	1.7	Parallel R-L Circuit Across Sinusoidal Supply																										. . . . .	. . . .	. . . . .	. .	.	... .. ... .. ... .. ... .. ... .. ... .. ..... .. .. .. ... .. ... .. . .... .. . .. . .. .. .. ..								66
	1.10	Parallel Resonance. . . . . . . . .																				. . . . . .. . . . . . .. . .. . .. . . . . . ... .. . . . . . .																			80
		1.7.1	Parallel R-C Circuit Across Sinusoidal.																							Source. . . .. . . . . .							.......	. .. .. .. . .. .. . . . . .							67
	1.11	1.7.2	Series Parallel Circuits of R, L and C																										. . . .	. . . . .	. .	.	. . . . . . .	. . . . . . . . . . . . . . . .	. . .	.	.		. .		68
	1.11	Magnetic Circuits . .											.. . .. . ... . . .. .. ... . . . . .... .... .... .... ... . .. . .. . .. . .. . ... . .. .... ... . . . . . . . . . ... ... ... ... .... . .. . . . . .																												91
	1.8	Resonance																											.	. .. .	.. .	..	. . . . . ...	. . . . . . . .. . . . . . . . ..	. .. .	..	.		.. .		69
		1.11.2 Leakage Flux.									. .			. .				. .					. .				.		. .		. .			. . . . .		. . .					98
		1.11.3 Fringing of Flux. ..									..	. .	. .	. .. .		. .. .. .. . . . . . .. . ... . . . . .. . .... .. . . ..... .. .. . . . . . .... . .																									99
		1.10.1 Q of Parallel RLC Circuit																										. .				.		. . . . . .				. .			85
																. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
							. . . . . . . . . . . . .																. . . . . . . . . . .											. . . . . . . . . .
		1.11.1 Analyses. . . . . . . . .between. . . . . . . . . . . . . . . Magnetic. . . . . . . . . . . . . . . . .and. . . . . . . .Electric. . . . . . . . . . . . . .Circuits. . . . . . . . . . . . .																												.. .. .. . .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .... .... .. .. .. .. .. .. .. . .. . .. .. .. .. .. .. ..											92
								. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
										. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
	1.12	Dot Convention for .Coupled. . . . . . . . . . . . . . . .Circuits. . . . . . . . . . . . .																			. .. .. .... .. . .. . .. .. .. .. .. .. .. . . . .. . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. . .. . .. . .. ..																		. .	102
2	.NETWORK THEORY					.	.		. .	.		.	. . .	.	.	.		.	.			. . .	.	.	.	.	. .	. .	. .	. .	.		. . .	. . . . . . .	.				119
	2.1	Introduction																																						119
	2.2	Kirchhoffs Laws																																						119
	2.3	Star-Delta Transformation																																						122
	2.4	Loop	Analysis	.	. .	.	. ....		.		.	.	. .		.. ... . . . . . . .... . . ... . . ... .																		..... . . . . .. . . ... .							125
	2.5	Nodal Analysis																																						130
	2.6	Superposition Theorem											. ...	.	.		.					. . . ..						. ... . . .					.	. .			.			134
	2.7	Thevenin's Theorem. . . .. . .. . . . . . . .						.	. . .. .	.	.	. . .	. . .. . .. .	.. . .. .	.	.. . .	.	..	. .	.	..	. .. . .. . .	. . .. . ..		. . .	. .. . .	. . .. . .	. .. . .. .	... .... .	.. . . . .	. . ....		. . . . . .. .	.. . .. . .. . .. . . .. . .. . .. . .	. ...	..	.	.		136
	2.8	Norton's Theorem. .					. . . .	.	. . . .	.	.	. .	. . . . . .	. . . ..	.	. . .	.	.	. .	.	.	. . . . . .			. . .	. . . .		. . . . . .		. . . . .			. . . . . . .		. . .	.	.			140
	2.9	Maximum Power Transfer Theorem. . . . . . . . . . . . . . . .																		.	.	. . . . . .			... ..	. . . .		. . ... .		. . . . ..			. . ... ... ..		... ..	.	.			144
						. . .					. .			. .					. .
					. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .
										.	.	. .	. . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
									. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
							. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3	THREE PHASE SUPPLY																		.	.	.	. . . . . .	.	.	.	. . . .	. .	. . . . .	. . .	. . . .	. .	.	. . . .	. . . . . . . . . .	. . . .				160
3	THREE PHASE SUPPLY							.	.	.		.	. . .	.	.	.		.	.			. . .	.	.	.	.	. .	. .	. .	. .	.		. . .	. . . . . . .	.				160
	3.1	Three Phase Circuits										. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .																												160
	3.2	Analysis of Star Circuits																																						164
	3.3	Delta Circuits		. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .																																				169
	3.4	Measurement of Power. . . . .in. . . .3. . . .-.Phase. . . . . . . . .Circuits. . . . . . . . . . . . . . .																							. .. .. .. . . . .. . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. . .. . .. . .. ..															172

		3.4.1	Three Wattmeter Method								xiii									172
		3.4.2	Two Wattmeter lVIethod																.	173
		3.4.3	One Wattmeter Method ........								.	...... . ........		........	.	........ ........	. ........	. ......		175
	3.5	Measurement of Reactive Power																		176
4	BASIC INSTRUMENTS						. . . .	.	. .	. . .	. . . . .	. .	. . . . . .	.	. . . .	. . . .	. . . . .	. . .		181
4	4.1	Introduction ........				.	......	. ......		. .........	. . . . . ... ........ . . . .	. .. . .........	. . . . . . . . .. . .......... . . . .		. . . .......... . . . . . .	. .......... . . . . . .	. ... ... ........ . . . . .	... ........ . . . .		181
	4.2	Types of Instruments								. . . .	. . . . . . . . . . . . .	. . . . .	. . . . . . . . . . . . . . .		. . . . . . . . . . .	. . . . . . . . .	. . . . . . . . . . .	. . . . . . . . .		181
		4.2.1	Permanent Magnet Moving Coil. . Type. . ...... ........... . ......... ......... .... ....... .........																	182
	4.3	4.2.2	Dynamometer Type Moving. . . . Coil. . . . . . . . . .Instruments. . . . . . . . . . . . . . . . . . . .												. . . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .		183
	4.3	Moving Iron Type																		185
		Induction Instruments																		186
	4.4	4.4.1	Induction.	Disc. . Type. . or. Shaded. . .								Pole. . Type. .. ........			. ........	. . .........	. .. ......	. .. .......		186
		4.4.2	Induction Cylinder. . . . . . .Type. . . . . . . . . .Instrument. . . . . . . . . . . . . . . . . . . .										. . . . . . .. . . . . . . . .		. . .. . . . . . . . .	.. . . . . . . . . .	. . . . .. . . . . . .	.. . . . . . . . . .	.	188
		4.4.3	The Shunt										. . . . . . .. . . . . . . . .		. . .. . . . . . . . .	.. . . . . . . . . .	. . . . .. . . . . . .	.. . . . . . . . . .	.	188
		4.4.4	High Series Resistance (Voltage Indicating Instrument). . . . . . . . . . . . . . . . . .... . . .														.. . ... ........ . . . .	. .. . ........ . . . . .		189
	4.5	Wattmeter				. . .	. . . . . . .	. . .	. . . . . .	. . . . . .	. . . . . . . . . . . . .	. . . . .	. . . . . . . . . . . . . . .	. .	. .. . . . . . . . .	.. . .. . . . . . . .	. .. . .. . . . . . .	.. . .. . . . . . . .	.	192
	4.6	Methods of Connection in. . . . .the. . . . . . .Circuit. . . . . . . . . . . . ......... . . . . .										. . . .........	. . . . . . . . .. . ......... . . . . .							195
	4.7	Energy Meters																		196
		4.7.1 Single Phase Induction Type Energy											.Meter. . . . . . . . . . . . . . . .		. . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .		196
	5.1	4.7.2	Creep		. .	. . .	. . . . . . . .	. .	. . . . . .	. . . . . .	. . . . . . . . . . . . .	. . . .	. . . . . . . . . . . . . . . .	.	. . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .	. . . . . . . . . .		198
	5.1	Introduction. . .......... . . . . . . . .. . ....... . . . . . . .. . ......... . . . . . . . .. ......... . . . . . .. . .. .. . ....... . . . . . .. .. .. ......... . . . . . . . .. . ......... . . . . . . .. . . .. ......... . . . . . . . .. ......... . . . .. . . . . .. .. .. .. ........ . . . . . .. .. . ....... . . . . . ..																		203
		4.7.3	Friction Compensation . ......								. ........	. ........	........		. ........	.........	.. .. .... ..	.........	.	198
		4.7.4	Meter. . .Phase. . . . . . . . . . . .Angle. . . . . . . . . . Error. . . . . . . . . . . .								. . . . . . . . . . . . .	. . . .	. . . . . . . .. . . . . . . . .. .		. .. . . . . . . . .	.. . . . . . . . . .	. . . . .. . . . . . .	.. . . . . . . . . .	.	199
	4.8	Polyphase Induction Watt Hour Meters .											. . . . . . . .. . . . . . . . .. .		. .. . . . . . . . .	.. . . . . . . . . .	. . . . .. . . . . . .	.. . . . . . . . . .	.	199
	4.9	Phantom or Fictitious. . . . . . . . . . . .Load. . . . . . . . . ... . .								.. . ......... . . .	. . . . .. .......... . . . . . .	.. .... .........	. . . . . . . .. .......... . . . . . .	.	. .... ........ . . . . . ..	. .. ......... . . . . . . . .	. .... .... ...... . . . ... .. .......... . . . . . . .		.	200
5	TRANSFORMER . . .			.	.	.	. . .	.	. . .	. .				.						203
	5.2	Construction								. .				.						204
	5.3	EMF Equation of a Transformer												.						205
	5.4	No Load Operation								. .										206
	5.5	Operation of Transformer Under Load Condition																		208
	5.6	Equivalent Circuit									. .	. .	. .		.	.	. . .	. .	.	210
	5.7	No Load or Open.			Circuit. . . .Test .						. .	. .	. .		.	.	. . .	. .	.	214
	5.8	Short-Circuit. Test. . . . . . . .				.. . .. . .. .. .. .. .. .. .. .. .. .. .. .. . . . .. . . . .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . .. . . . . . . .. . .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. . . . . .. . . . . .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. ..														215
	5.9	Voltage Regulation					. . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . .. . . . . . . .. . .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. . . . . .. . . . . .. .. .. .. . . . . . . .. . . . . . . .. .. .. .. .. .. .. .. ..													217
	5.10	Losses in a Transformer. . . . . . . . .						.. .........	. . . . . .	. .. .. .. ....... .	. . . . .. .. .. ....... . . . . .	.. .. .. .........	. . . . . . . .. .. . .......... . . . .. .		. .. .......... . . . . . .	.. .. .. ......... . . . . . .	. .. .. .. ....... . . . . .	.. .. .. ........ . . . . .	.	221
	5.11	Efficiency of Transformer							. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. . . . . .. . . . . .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. ..											222
	5.12	Polarity of a Transformer. . . . . . . . . . . .							.. .. .. . . .. . . .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . .. . . . . . . .. . .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. . . . . .. . . . . .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. ..											228
	5.13	Testing of Transformers						. . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . .. . . . . . . .. . .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. . . . . .. . . . . .. .. .. .. . . . . . .. . . . . . .. .. .. .. .. .. .. .. .. ..												231

5.13.1	Sumpner's Test							.......................................................................			xiv												................				231
5.14 Auto Transformer				....................			.............................................................				.												. ................				232
											.												. ................
5.14.1	Saving in Copper .................................................in Auto Transformer																	.		. .		.	.	. .		.	234
		.		.		. .		. .		.		.		.		. .		.		. .		.	.	. .		.
6 D.C. MACHINES			. . .		.		.		.		. . .		.		. .		. . . . .		. .		.		. . . . .		.		. 245

6.1

6.2

6.3

6.4

6.5

6.6

6.7

6.8

6.9

6.10

Introduction ............................................................................................................																			245
Construction										.									245
EMF Equations				.... ................................................							................................................								247
6.3.1	Armature Reaction					. . . .		. . .			. ...		. . ...		. . .		. . .		248
6.3.2	Commutation .........................						...........................................................									.........			251
Classification of DC Machines						.........	...........................................................									.........			253
Magnetisation Characteristics						..........	..................................................		. . . . . . . . .. .. . . . . . .. . . .. . . . . . . . . . .. . . . . .................. . . . . . . . . .. . . ..										256
Terminal		Characteristic of Shunt Generator																	257
Terminal			. . . . . .	. . . . . . . . . .. . .	. . .. .. . . . . . .. .. .. .. .		. . . . . . .. . . . .	. .											257
6.6.1	Series Generator.				Characteristic ...... .......................................					.					. .................				257
6.6.2 Load Characteristics. . .of. . . . . . . . . . . .Compound. . . . . . . . . .Generator. . . . . . . . . . . .......................												. . .	. . . . .	. . . . . . . .. ......... . . . . . . . ........ . . .					258
DC Motors							.									.			261
6.7.1	DC Shunt Motor				.............................................................		.. . .		. ...		.	...		............ .................					261
6.7.2	DC Series Motor . . .						.. . .		. ...		.	...		. . . .	. .	.	.	. .	263
					. . . . . . . . . . . . . . . . . . .		. . . . . . . .	. .	.	. . . . . . . . .			. . . . . . . . . . .		. . . . . . . .	. . . . .	. . . .	. .
6.7.3	DC Motor Starter...........................................................									.			.		. ................			.	264
Losses in DC Machines					.					.			.		. ................			.	265
Losses in DC Machines					.......................................		.				................................................. .								265
Efficiency of DC Machines ..................................................................													.		. ... ................	.			266
Swinburne			Test										.		.				268
Swinburne			. . .. .. .. .	. . . . . . . . . . ..	. . . . .. . . . . . . .. . . . . . . . .		. .. . . . . . . . .	. .	. . . ..	.	. . . . . . . . . .	. . ..	.		.	. . . . . .	. . . . .	. .	268
				.. . . . . . . . . . .. . . . . .. . . . . . . .. . .. . . . . . . .. . . . . . .. . . .. .. . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. .. . . . . .

7 THREE-PHASE SYNCHRONOUS MACHINES . . .							. . . .	. . . .	. . . . .	.	. . . . . .	276
7.1	Introduction ................................................					........	.................................................					276
7.2	Construction .........................................................						.................................................					276
	7.2.1	EMF Equation.................................				..........	................................				................	277
	7.2.2	Rotating Magnetic Field										280
	7.2.3	Armature Reaction ................			.......... ........		..........	.....................			................	283
	7.2.4 Open Circuit and Short Circuit Tests on Alternator ................................											284
	7.2.5	Voltage. Regulation .....................................................................			.		.				................ 286
	7.2.6	Losses.and Efficiency ...............................................................					..			. ................ 287
	7.2.7	Magnetic Poles in Machines .			......................................................		..			.	............... 288
	7.2.8	Steady State Operation		..............................................................								288
	7.2.8	Steady State Operation		. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. .. . . . . . . . .. .. .. . .		.	.	.		...	. ................. . . . . . . . . . . . . . .	288
	7.2.9	Power and Torque .....................................................................		.		.	.	.		...	........ ....... 289
7.3	Effect of Excitation on Armature Current ......... ................................									.	................	291
7.4	Change of Load									.		. 292
			.. . . . .. . . .. .. . . . .. . . . . . . . . .. . . . . . . . . . . . . .. . . . .. .. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . .. .. . . . . . . . .. .. ..
7.5	Starting of Synchronous Motor .............................................................						.			..	................	292
	7.5.1	Damper Winding Starting .........................................................								..	................	. 292
	7.5.2	Auxiliary Motor Starting ...........................................................								.. ................		293
7.6	Speed Torque Characteristic ...........			....................................... .............	.				.	.. .................		294
					.				.	.

	7.7	Synchronous Condenser								xv									.		294
	7.8	Applications		. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .																	296

	7.9	Stepper Motor .... .			.........			........	. . ........	.	. ......	..	.	........ . ......	...	........ ........	.... ....	.	.	. ......	299
		7.9.1	Permanent Magnet Type																		. 299
		7.9.2	Comparison of Stepper Motors																		. 302
		7.9.3	Application		......		.	....MOTORS...... ... .......			.... ............ ..			................. ... ............................................ . ......			....... ............. .... .............				302
8	THREE-PHASE INDUCTION.							....MOTORS...... ... .......													304
	8.1	Introduction		...........	........................... .																304
	8.2	Construction					. . . . . . . . . . . . . . . . .. . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . . .. . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .														304
	8.3	Principles of Operation																			305
	9.1	Introduction																			328
	8.4	El\/[F and Current			. Relations.				. .			. .		. .	.	.	. .		..		306
	8.5	Mechanical Power Developed . ........									. ......	.. ... ........		.. .. ......	.	........ .........	.. .... ....	..	. .. ......		308
	8.6	Starting of 3-Phase Induction l\/Iotors																			315
	8.7	Industrial Application. .								. .											325
	9.4	Application .				. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .															335
9	SINGLE PHASE INDUCTION. . . . . . . . . . . . . . . . . . . . . .MOTORS. . . . . . . . . . . . . . . . . .										.. . .. . ...	... . ..	.	... . .. . ... ... . ... ... . .. .	. .... ........... . ... ... . .... ............ ... . ... ....... ..... ....... ... .. .... ............ . .. . ... .						328
	9.2	Principle of Operation ..						.........	.. ........	..	.. ......	...	........	...........							.. 329
	9.3	Starting of Single Phase Induction Motors. . . . . . . . .											.	. . . . . . . . . . . . . . . . . .	. .	. . . . . . . . . . . . . . . . . .	. . . . . . . .	.	. .	. . . . . . .	331
10	POWER SYSTEM. .. ... ... . ... .. .... . ..... .. ..... ..... .. ..... ..... ..... .. ..... .... . .. ..... ... .. . .... .. ..... ..... .. ... .. ..... ..... .. ... .. ..... .. ..... ..... ..... .. ... ... . .... . . . . . . ..... .. ... .. ..... ..... .. ... .. ..... ..... .. ..... ... .. .. ... .. ..... ..... .. .... ..... .. ... .. ..... .. ..																				342
	9.5	Universal Motor																	.		335
	9.6	Synchros					.		.		.			.	.		. . . .				337
	9.7	DC Tachometer. . . . . . . . . .			. . . . .	. . .		. . . . . . . . .		. . . . .		. . . .	.			. . . . . . . . . . . . . . . . ...				. . . . . . . .	338
	9.8	AC Tachometer																			338
	9.9	Two Phase Servomotor											.	. . . . . . . ... . . . . . . . . .	. .	. . . . . . . . . . . . . . . . .	. . . . . . . . .	.	..	. . . . . . . .	339
	10.1	Introduction. . . . . .		. ......... . . . . . . . ..	... ....... .	. . . .	.. ..	.. ....... . . . . . . ..	.. ......... . . . .	. . . .	.. .. ........ . . .	. . .. .	.........	. . . . . . . . .. . ......... . . . . . .	...	......... . . . . . . ... .. . ........ . . . . .	.... ... ........ . .	. .	.	.. .. ....... . . . . . ..	342
	10.2	Types of Distribution. . . . . . . . . .System. . . . . . . . . . . . . .							. . . . . .	. . . ..	. . . . . . .	. . . .	.	. . . . . . . . . . . . . . . . . .	. .	. . . . . . . . . . . . . . . .	. . . . . . . .	. .	.	. . . . . . . . ..	343
		10.2.1 The Radial. . . . .Systems. . . . . . . . . . . . . . ............... . . . .							. . . . . .	. . . . .	. . ....... . . . .	. . .. .	.........	. . . . . . . . .. . ........................... . . . . . .	. . .	. . . . . . . . . . . . . . . .	.... . . . ....... . . .	. .	.	.. . ........ . . . . .	343
		10.2.2 The Ring Mains.					Systems. . . . . . . . . . . . . . . . .			. . . . .	. . . . . .	. . . .	.	. . . . . . . . . . . . . . . . .	. .	. . . . . . . . . . . . . . . . .	. . . . . . . . .	.		. . . . . . . . .	344
	10.3	Cost Comparison of Supply Systems																			. 344
		Power Factor Improvement ..												. .	.......... .........		.. . .. .................				347
	10.4	10.4.1	Causes. of Low.			p.f . .			........	.	. ..........................	. .		. .	.......... .........		.. . .. .................				349
		10.4.2 Methods to Improve p.f. . . . . . .								. . .	. . . . . . .	. . . .	.	. . . . . . . . . . . . . . . . . .	. .	. . . . . . . . . . . . . . . . .	. . . . . . . . .	.	.	. . . . . . . .	349
	10.5	10.5.4	Wave Power				.	. . . . . . . .	.. . .. . . .. . . .. .. .. .. .. .. .. .. ............ .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . .. . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .... .. .. .. .. ...												355
	10.5	Generation-Non-Conventional Sources. .										. .		. .			. .		.. .		352
		10.5.1	Tidal Power									. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .								. . . . . . . . .	353
		10.5.1	Tidal Power			....	. .. ........		. ....... .	. .. .... .... ........ . . .		. .. .... .	........	. . . . . . . .. .......... . . . . . . . .	. ... .	......... . . . . . . .. .......... . . . . . . .. .	... .... ...... . . .. ................ . . . . ..				353
		10.5.2	Wind Power			. . . . . . . . . . . . . . . . . . . . . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . . .. . . . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .															353
		10.5.3	Geothermal			Power ......................			.	. .		.	.	.................. .		...................... . . . ....		.		......... 354
												.	.		. .		.	. .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

					(MHD) Generation																				.									356
	10.5.5 Magneto Hydro Dynamicxvi
10.6	10.5.6	Solar Energy ............................................................................................																																356
10.6	Conventional Sources . . .			. . . .	... . . .				. . . . ... . . . . .																		. ... .						.	357
	10.6.1	Hydro Station																																357
	10.6.2	Steam Power Plant														. .						.			. . . . . .							. . .		358
	10.6.3	Nuclear Power Plant . . ... .				. .	.	.	.	.		.	.		.		. .		.		.		.	..				.... .			.		.	358
	11.2.1	Cleat Wiring		. . .	. . . .	. . . . . .	. .	.	.	.	. . . . . . . .		. . .	.			.	. . .			.		.					.			.			361
	10.6.4	The Gas Turbine Plant			. . . . . . . . .. . . .. . . . . . .. .. .. . . . . . . . . .... .. ...... ... .... .... . ........ ... ........... ........ ... ... .... .... ....... . . . .. .. ........																													358
11 DOMESTIC WIRING																																		361
11 DOMESTIC WIRING				... . ..... .... .............. ..... ... ...... ... . ............ .... ..... ..... .. ..... .... . ... .. ........... ....... . ... . .... ..... ...... .. .. ..... .. .... . .... .. ..... .... ......... .... .. ... .. ..... .. .																														361
11.1	Introduction . . .																																	361
11.2	Types of Domestic. . . . . . . . . .Wiring. . . . . . . .......																																	361
11.2				. .. . . . . .	. .... ....	.. .. . . . .	. . .	. .	. .	.....		.. . . .	....	..		.. . .	. .	.. .		.	. . .		. .	. ..	.. .		..	. . .		. . .	. .	....		361
	11.2.2	Wooden/PVC Casing and Capping Wiring																									.. .				. . .. 362
	11.2.3	Toughened Rubber Sheath (TRS or CTS) or Batton Wiring																																363
	11.2.4	Conduit Wiring																												. . . ..				363
11.3	Specifications of Wires ..					...				. .		. .			.		...		.				. .			.		.	.		.	. .		364
11.8	Fuses and HRC Fuses . . . ... ... . ... .. . . ..... . . . . . . ... . ... ... ... ..											. . . . ... .. . . ..				. . .. . ..				... ... .... .. .							. . .....				.	.	.. 372
	11.3.1 Size of Conductor ....................................................................................																											. . . .			. .			365
					. . .... . . .	. . . ........		.	. . .	. .	.	.. .. .. .	. . . . .	.		.. ..	. . . .	.		. .	. .		. .	. .	. .		. ..
11.4	Distribution Board .. . . .			. . . . . . ..... .	. . .. ......	. . . . .. . .. .	. ..	....		.. .	..	. . .. .. .	. . . . .	.	.	. . .	. . . .	.		. ..	.		. ....		. .		. . .							367
11.5	Types of Cables											. . .	. . . . .	.		. .	. .			.	. .		.	.	. .		.							368
11.6	Lighting Control Circuits			.. .. . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . ...... .. ... . . . . .. .. .. . . . . . . . .. . . . . . .																						. . ... ................ .. . ... . . .								368
REFERENCE . . .		. .	. . . . .. ... ... . ... ... . ... ...																							. . ... ................ .. . ... . . .								401
11.7	Earthing System .			. . . . . . . . . . . ..	. . . ....... . . . .. . .. .. .. . ... .. .. . .. ... . .. . .. .. . .. . .. .. . .. . .. .. ... . .. .. . .. .... . . .. .. . .. . .. . .. ... .. . ... . . .. . .. . .. . .. .. . . . .. . .																													370
			. . . .	. . . . . . . .
	11.8.1	Calculation. . .of. . . .Fuse. . . . . . . . .Rating. . . . . . . . . . . . ...................................................................... . . . .				. . . . .	. . .	. .	. .	.	. .	. . . . . .	. . . . .	.		. . .	. . . .	.		. .	. .		. .	. .	. . .		. . .	. .	. .	. .	. . . .			377
MULTIPLE CHOICE			QUESTIONS	. . . . .	. . . .	. . .	.	.	.	.	.	. . .	. .			.	. .			.	.		.	.	.		.	.	.	.	.			379
MULTIPLE CHOICE			. . . . . . . . . . . .. . . .	. . . . . . . . . . ..	. . ........ ...	. . . .	.. . .	. .	. .	. .	. . .	.. .. ..	. . . . .	.		. . .	. . . .	.		. .	. .		. .	. ..	..		. .	. . .	. .	..	.. . . .			379
INDEX . .	. . . . . . .	. .	. . . . . . . . . .	. . . . .	. . . .	. . .	.	.	.	.	.	. . .	. .			.	. .			.	.		.	.	.		.	.	.	.	.		403

CHAPTER

•
I	DC Circuits
	DC Circuits

i.1 INTERNATIONAL SYSTEM OF UNITS

The international system of units abbreviated as SI has been universally accepted for international use in all fields ofengineering and day to day requirements. Therefore, all business and even household transactions are conducted in SI units. SI system offers the following advantages over other system of units.

1.There is one and only one unit for each physical quantity. Therefore, a table of conversions from one unit to another is not required.

2.The system is coherent with the derived units. The conversionfactorfrom the original

unit to the derived unit is simply a multiplication or division by 1. e.g. a motor or3

an automobile engine is now rated as in kW rather than horse power. Energy is now expressed in watt-sec rather than in Joule etc.

There are a large number of quantities (more than thirty) which an electrical engineer deals in. Howeverit is not necessaryto assign a standardunit to eachquantity as these quantities are functionally related through experiments, mathematical derivation or definitions. The minimum number of quantities required to express the units of all other quantities are known as fundamental quantities. The following are the considerations for selection of fundamental quantities.

(i)A minimum number ofconstant should be required to establish relationship between the various quantities involved in the study of the given discipline.

(ii)The measuring units shall he of a practical size.

There are sevenfundamentalunitswhich arelistedbelowwith their name, quantity symbol and unit symbol.

1.Length-metre, l, m

It is defined in terms of wavelengths of a particular radiation from krypton 86.

2.Mass-kilogram, m kg

It is defined equalsto the mass of the international prototype kept in Sevres, France.

3.Time-seconds, t,

It is defined in terms of the duration of a specific number of periods of a particular radiation from the cesium-133 atom.

4.Current-ampere, I, A

It is defined as the constant electric current in two infinite parallel conductors separated from each other by 1 m, produce a force of 2 x 10-9 Nim.

2	ELECTRICAL ENGINEERING

5. Temperature-Kelvin, T, K

It is defined as the fraction 273_16 of the thermodynamic temperature of water at

which point it is simultaneously a gas, a liquid and a solid (the trip point). 6. Quantity-mo!, mol

It is defined as the amount ofsubstance which contains as many elementary particles as there are atoms in 0.012 kg ofcarbon 12.

7.Light-Candela, I, Cd

It is defined as the light intensity of the freezing point of platinum under specified conditions.

The supplementary units used for two and three dimensional problem related to

geometry are :

1. Phase angle, radian rad

2. Solid angle, Steradian Sr

At serial no. 4 we have taken current as the fundamental quantity. However, from a purely

theoretical consideration the fourth fundamental quantity could be taken as charge which has the fundamental unit couloumb. It is possible to derive current from charge and vice versa. However, the reason for selection of current rather than charge as the fundamental quantity is that ampere serves as the link between electrical, magnetic and mechanical quantities and is more readly measured.

Even though it is possible to function with the sevenfundamental units mentioned above, yet if a set of derived units are defined with special names, the resulting equations and calculations are greatly simplified Table i.1 lists the Derived units in S.I.

	Unit	Table	Quantity	Unit
			i.1 SI Derived units
					Expression in
		Name			Terms of
			Symbol	Symbol	Other Units
1 .	Absorbed dose	gray		Gy	J/kg
2.	Activity	becquerel		Bq	s-1
3.	Electric	farad		F	C!V
	capacitance		G	s	A/V
5.	inductance	siemens	G	s	A/V
4.	Electric	siemens	c
	conductance
	Electric	henry	L	H	Wb/A
6.	Electric potential	volt	V,E		W/A
	difference		R	Q
7.	Electric	ohm	R	Q	V/A
	resistance			v
8.	Energy	joule	w	J	N.m
9.	Force	newton	F	N	kg.m/s2
10.	Frequency	hertz	f	Hz	s-1
10.	Frequency	hertz		Hz	s-1

DC CIRCUITS				E		3
11.	Illuminance		lux	E	lx	lm/m2
12.	Luminous flux		lumen	<P	lm	cd.sr
13.	Magnetic flux		weber	<P	Wb	V.s
13.	Magnetic flux		weber		Wb	V.s
14.	Magnetic flux		tesla	B	T	Wb/m2
	density
15.	Power		watt			J/s
16.	Pressure stress		pascal	p	Pa	N/m2
17.	Quantity	of	coulomb	p	c	As
17.	Quantity		coulomb	p	w
	electricity;			Q
i.2 CIRCUIT
An electric circuit is a closed path consisting of active and
passive elements all interconnected and the current flow
is confined to the closed path. Fig. i.l shows a typical cir
cuit consisting ofone active and two passive elements. An
active element is one which supplies energy to the circuit
where as a passive element is one which receives energy
and then this energy is converted into heat (resistor) or
stores it in an electric (capacitor) or magnetic field (induc					Fig. i.1	Electric circuit.
tor). The battery is the active element in Fig. i.l.

i.3 ELECTRIC CURRENT

The concept of charge is based on atomic theory. An atom has positive charges (protons) in its nucleus and an equal number of electrons (negative charges) surround the nucleus making the atom neutral. Removal of an electron leaves the atom positive charged and addition of an elec tron makes the atom negatively charged. The basic unit ofcharge is the charge on an electron. The mks unit of charge is coulomb. An electron has a charge of 1.062 x l0-19 C.

When a charge is transferred from one point in the circuit to another point is constitutes what is known as electric current. An electric current is defined as the time rate of flow of charge through a certain section. Its unit is ampere. A current is said to be ofone ampere when a charge of 1 coulomb flows through a section per second.

Mathematically,

i. =	dq	(i.l)
	-
	dt

If charge q is expressed in coulomb and time in second, 1 amp flow of current through a section is equivalent to approx. flow of 6.24 x 1018 electrons per second through the section.

Yet another method of defining electric current (1 amp) is as the constant electric current in two infinite parallel conductors separated from each other by 1 m, experience a force of 2 x 10-9 Nim.

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