Electrical technology. Volume II, Machines and measurements

✍ Scribed by Bali, S. P

• Publisher: Pearson
• Year: 2013
• Tongue: English
• Leaves: 452
• Series: Always learning
• Category: Library

✦ Table of Contents

Cover......Page 1
Dedication......Page 4
Preface......Page 6
Contents......Page 8
Part B: Electric Machines......Page 14
31.2 Energy Conversion Devices......Page 16
31.3.1 Faraday’s Law of Induction......Page 17
31.4 D.c. Motor and Generator Mechanical Construction......Page 19
31.5 Elementary Generator......Page 20
31.8.1 Motor Action......Page 22
31.8.3 Magnitude of the Mechanical Force......Page 23
31.8.5 Left-Hand Rule of Motor Action......Page 24
31.10.1 Generator Power Flow......Page 26
31.10.2 Motor Power Flow......Page 27
31.11 Conversion Process in a Machine......Page 28
31.12 Linear and Rotary Motion......Page 29
31.13 Methods of Analysis......Page 30
31.14 Energy Balance......Page 31
Summary......Page 33
Conventional Questions (CQ)......Page 34
32.1 Introduction......Page 35
32.2 Mechanical Construction......Page 36
32.3 Armature Structure......Page 37
32.4 Commutator and Brushes......Page 38
32.5 Armature Windings......Page 39
32.5.1 Lap Windings......Page 40
32.5.2 Wave Windings......Page 41
32.5.4 Paths in Lap-Wound and Wave-Wound Armatures......Page 42
32.6 Commutation......Page 43
32.7.1 Correcting Armature Reaction Effect......Page 44
32.8 E.M.F. Equation......Page 45
32.10 Basic Generator Types......Page 48
32.11.1 Shunt Generator......Page 49
32.11.2 Series Generator......Page 50
32.11.3 Compound Generator......Page 51
32.12.1 Separately Excited Generators......Page 52
32.12.2 Shunt Generator......Page 53
32.14 Polarity of Brushes......Page 56
32.16 Paralleling of Generators......Page 57
32.16.1 Parallel d.c. Generator Requirements......Page 58
Summary......Page 59
Multiple Choice Questions (MCQ)......Page 60
Conventional Questions (CQ)......Page 61
33.1 Introduction......Page 64
33.2 Development and Measurement of Torque......Page 65
33.3 Prony Brake......Page 66
33.5 Dynamometer......Page 67
33.6 Back Electromotive Force in a Motor......Page 68
33.7 Classification of Motors......Page 70
33.8 Construction......Page 71
33.9.2 Shunt Motor Speed Characteristics......Page 72
33.9.5 Series Motor Speed Characteristics......Page 73
33.9.8 Compound Motor Speed Characteristics......Page 74
33.10.1 Torque Versus Speed......Page 75
33.11 Direct-Current, Motor Starting Problems......Page 78
33.12 D.c. Starting Switch......Page 79
33.13.1 D.c., Motor Reversing Circuit Connections......Page 82
Multiple Choice Questions (MCQ)......Page 83
Conventional Questions (CQ)......Page 84
34.2 Basic Efficiency Relationships......Page 86
34.3.2. Winding Resistance Losses......Page 87
34.3.3 Shunt Field Loss......Page 88
34.3.4 Relationships Between Losses......Page 89
34.4 Motor Enclosures......Page 91
Summary......Page 92
Conventional Questions (CQ)......Page 93
35.2 Control Devices......Page 94
35.3 Pilot Control Devices......Page 96
35.4.2 Three-point Starter......Page 98
35.4.4 Drum Rotary Switch Starter......Page 99
35.4.5 Direct-current Three-point Starter Circuit......Page 100
35.7 Reversing Control of Direct Current Motors......Page 101
35.7.1 Manual Reverse Control......Page 102
35.8.1 Electric Brakes......Page 103
35.8.2 Jogging......Page 104
Summary......Page 110
Conventional Questions (CQ)......Page 111
36.1 Introduction......Page 113
36.2 Mutual Coupling......Page 114
36.3 Series Connection of Mutually-Coupled Coils......Page 115
36.4 Parallel Connection of Mutually Coupled Coils......Page 116
36.5 The Dot Convention......Page 117
36.6 Preventing Mutual Inducance......Page 118
36.8 Transformer Construction......Page 119
36.9 Ideal Transformer......Page 121
36.10 Transformation Ratio......Page 123
36.11 General Transformer Equation......Page 124
36.12 Practical Transformer......Page 126
36.13 Transformer Ratings......Page 128
36.14.1 Reflected Impedance......Page 130
36.l4.3 The Three Winding Transformer as an Impedance Matching Device......Page 131
36.14.4 Tapped Matching Transformers......Page 132
36.14.5 Equivalent Circuits......Page 133
36.15.2 Lagging Power Factor Voltage Relations......Page 134
36.17 Maximum Power Transfer......Page 135
36.18 Losses in Transformers......Page 137
36.20 Open Circuit Test......Page 138
36.21 Transformer Efficiency......Page 139
36.22 Autotransformer......Page 140
36.22.2 Autotransformer Power Division......Page 141
36.23.1 Parts of a Transformer......Page 142
36.24 Instrument Transformers......Page 143
36.25 Pulse Transformers......Page 144
36.26 Transformer Connections......Page 145
Summary......Page 147
Conventional Questions (CQ)......Page 148
37.2 Three-phase Connections of Single-phase Transformers......Page 150
37.3 Three-phase Transformers......Page 154
37.5 Harmonic Suppression in Three-phase Connections......Page 155
Multiple Choice Questions (MCQ)......Page 157
Conventional Questions (CQ)......Page 158
38.1 Introduction......Page 159
38.2.1 Fixed Armature or Stator......Page 160
38.2.2 Rotating Field Structure......Page 161
38.3.1 Chording of Windings......Page 162
38.3.3 Winding Distribution......Page 163
38.4 Synchronous Alternator......Page 164
38.5.1. Single-layer Winding......Page 166
38.5.2. Double-layer Winding......Page 167
38.6 Distribution Factor......Page 168
38.8 Alternator Performance......Page 171
38.10.1 Unity Power Factor Loads......Page 172
38.10.2 Lagging Power Factor Loads......Page 173
38.10.3 Leading Power Factor Loads......Page 174
38.10.4 Voltage Regulation at Various Power Factors......Page 175
38.10.7 Winding Resistance......Page 176
38.10.8 Synchronous Impedance......Page 177
38.10.9 The Open-circuit Test and The Short-circuit Test......Page 178
38.11 Equivalent Circuit......Page 180
38.12.1 Parallel Voltage Requirements......Page 181
38.12.3 Identical Frequency Requirement......Page 183
38.13.2 Phase Sequence Matching......Page 184
38.13.5 Synchroscope Synchronization......Page 186
Multiple Choice Questions (MCQ)......Page 187
Conventional Questions (CQ)......Page 188
39.2 General......Page 190
39.4 Synchronous Motor Operation......Page 191
39.5 Starting Synchronous Motors......Page 193
39.6 Synchronous Motor Power Factor Control......Page 194
39.7 Synchronous Motor V Curve......Page 195
39.8.1 Power Factor Correction Advantages......Page 198
Multiple Choice Questions (MCQ)......Page 200
Conventional Questions (CQ)......Page 202
40.1 Introduction......Page 203
40.2 The Rotating Magnetic Field......Page 204
40.3 Speed of the Rotating Magnetic Field......Page 206
40.5 Slip and its Effect on Rotor Frequency and Voltage......Page 210
40.5.2 Effect of Slip on Rotor Voltage......Page 211
40.6 Construction of a Three-phase Induction Motor......Page 213
40.7 Rotor Impedance and Current......Page 214
40.8 Locus of the Current......Page 216
40.9 Losses and Efficiency......Page 217
40.10 Air Gap Power......Page 219
40.11 Maximum Torque......Page 220
40.12 Induction Motor Torque-Speed Characteristics......Page 222
40.14 Starting Techniques for Induction Motors......Page 223
40.15 Determination of Induction Motor Parameters......Page 225
40.15.2 No-load Test......Page 227
40.15.3 Blocked-Rotor Test......Page 228
Summary......Page 229
Conventional Questions (CQ)......Page 230
41.1 Introduction......Page 232
41.2 Classes of Induction Motors......Page 233
41.3 Getting the Rotor Started......Page 234
41.5 Phase Splitting......Page 235
41.6 Locked-Rotor Torque......Page 236
41.7 Resistance-Start Split-Phase Motors......Page 238
41.8 Capacitor-Start Split-Phase Motors......Page 240
41.8.1 Permanent-split Capacitor Motors......Page 241
41.10 Dual-Voltage Operation......Page 242
41.11 Shaded-Pole Motors......Page 245
41.11.1 Reversing Shaded-pole Motors......Page 246
Multiple Choice Questions (MCQ)......Page 247
Conventional Questions (CQ)......Page 248
42.2 Reluctance-Start Induction Motor......Page 249
42.3 Hysteresis Motors......Page 251
42.4.1 Types of Stepper Motors......Page 253
42.4.2 Variable-reluctance Stepper Motors......Page 254
42.4.3 Permanent-magnet Stepper Motors......Page 255
42.5 Lim......Page 257
42.6 Universal Motors......Page 259
Multiple Choice Questions (MCQ)......Page 261
Conventional Questions (CQ)......Page 262
43.2 Operational Amplifiers......Page 263
43.2.3 Ideal Inverting Amplifier......Page 264
43.2.5 Non-ideal Effects......Page 265
43.2.6 Op Amp Specifications......Page 266
43.4 D.c. Servomotors......Page 267
43.4.3 Series Split-field d.c. Servomotors......Page 268
43.5 A.c. Servomotors......Page 269
43.6 Synchros......Page 270
43.6.2 Differential Self-synchronous System......Page 271
Multiple Choice Questions (MCQ)......Page 272
Conventional Questions (CQ)......Page 273
44.2 Control System......Page 274
44.3 Servomechanisms......Page 275
44.5 Automation......Page 276
44.7 Transfer Function......Page 277
44.8 Regulators and Servomechanisms......Page 278
44.10 Damping......Page 279
44.11 The Basic Feedback Control System......Page 281
44.11.1 The Frequency-response Approach......Page 283
44.12 The Integrator......Page 284
44.12.1 Integration in the Time Domain......Page 285
44.13 Steady-State Operation of a Compound Generator......Page 287
44.14 Automatic Frequency Control......Page 288
Summary......Page 289
Conventional Questions (CQ)......Page 290
45.2 Converting Machines......Page 291
45.3.2 VI Characteristics of Rectifiers......Page 292
45.3.3 Rectifier Operation......Page 293
45.4 Three-phase Full-wave Rectifiers......Page 296
45.5.1 Types of UPS: UPS Systems Can Be: (1) Online, (2) Offline or (3) Hybrid......Page 297
45.6 Inverters Changing d.c. Voltage to a.c. Voltage......Page 298
45.6.2 Three-phase Inverters......Page 299
Multiple Choice Questions (MCQ)......Page 301
Conventional Questions (CQ)......Page 302
46.1 Introduction......Page 303
46.3 Thyristor Control of Motors......Page 304
46.3.1 Controllable Semiconductor Diodes......Page 305
46.3.2 Operating States of the Thyristor......Page 306
46.3.3 Triggering......Page 307
46.5 Universal Motor Control......Page 308
Summary......Page 309
Conventional Questions (CQ)......Page 310
47.1 Introduction......Page 311
47.3 Impedance as a Per-unit Quantity......Page 312
47.4 Per-unit Quantities for Three-phase Circuits......Page 313
47.5 Per-unit System-Transformer Calculations......Page 314
47.5.1 Per-unit Magnitudes of a Transformer Defined......Page 315
47.5.2 Per-unit Transformer Copper Losses and Per-unit Equivalent Resistance......Page 316
47.5.4 Per-unit Transformer Currents......Page 317
47.5.5 Per-unit Voltage Regulation......Page 318
47.5.8 Changing Per-unit Base Quantity from One System to Another......Page 322
Summary......Page 326
Conventional Questions (CQ)......Page 327
Part C Electrical Measurements......Page 328
48.1 Introduction......Page 330
48.2 Definitions......Page 331
48.4 Factors Affecting Accuracy......Page 332
48.5 Measurement Systems......Page 333
48.6 Calibration......Page 335
Summary......Page 336
Conventional Questions (CQ)......Page 337
49.2 Design Principles......Page 338
49.4 Moving-Coil Instruments......Page 342
49.5.1 Types of Secondary Instruments......Page 344
49.6 Gravity Control......Page 345
49.7.1 Attraction Type......Page 346
49.7.2 Repulsion Type......Page 348
49.8 Polarized Moving-Iron Instrument......Page 349
49.9 Dynamometer-Type Instruments......Page 351
49.10 Induction-Type Instruments......Page 353
49.10.1 Ferraris-type Induction Instruments......Page 354
49.10.2 Shaded-Pole Type......Page 355
49.10.3 Induction-type Watt Meters......Page 356
49.11 Hot-Wire Instruments......Page 357
49.12 Thermocouple Instruments......Page 358
49.14 The Electrostatic Voltmeter......Page 359
49.14.1 Properties of Electrostatic Voltmeter......Page 361
Multiple Choice Questions (MCQ)......Page 362
Conventional Questions (CQ)......Page 363
Chapter 50: Ammeters, Voltmeters and Ohmmeters......Page 364
50.2 Special Features......Page 365
50.3.1 Ammeter Shunts......Page 367
50.3.2 Calculating the Value of Shunts......Page 368
50.3.3 Universal Shunt......Page 369
50.3.4 Calculating the Value of Universal Shunts......Page 370
50.3.4 Ammeter Loading......Page 374
50.4.1 Voltmeter Multipliers......Page 375
50.4.2 Voltmeter Loading......Page 379
50.5 Ohmmeters......Page 380
50.6 Measurement of Insulation Resistance......Page 382
Summary......Page 384
Conventional Questions (CQ)......Page 385
51.2 Watt Meters......Page 387
51.3 Dynamometer-Type Watt Meter......Page 388
51.4 Compensating Coil......Page 390
51.5 Induction-Type Watt Meters......Page 391
51.7 General Classification......Page 392
51.8.1 Commutator-type Meters......Page 393
51.8.2 Mercury-type Meters......Page 394
51.9 Alternating Current Types (Induction Watt-Hour Meters)......Page 396
51.9.1 Production of Fluxes Driving Torques......Page 397
51.9.2 Reading Watt-hour Meters......Page 399
51.11 Errors in Energy Meters......Page 401
51.12 Measurement of Power in Three-phase Circuits......Page 402
51.12.2 Three-ammeter Method......Page 403
51.13.2 Two-watt Meter Method of Measuring Three-phase Power......Page 404
51.13.3 One-watt Meter Method of Measuring Three-phase Power......Page 406
Summary......Page 407
Conventional Questions (CQ)......Page 408
52.1 Introduction......Page 410
52.2 Direct Current Ranges......Page 411
52.3 Direct Voltage Ranges......Page 412
52.5 Alternating Current Ranges......Page 413
52.6 Alternating Voltage Ranges......Page 415
52.7 V.O.M. Specifications......Page 416
52.8.1 D.C. Current......Page 420
52.8.2 D.C. Voltage......Page 422
52.8.4 Resistance......Page 423
52.9 Digital Multi-Meters......Page 424
52.9.2 Digital Voltmeters (Voltage D.C.)......Page 425
52.9.5 Resistance......Page 426
Summary......Page 427
Conventional Questions (CQ)......Page 428
53.1 Introduction......Page 430
53.2 Crt......Page 431
53.3 Intensity......Page 432
53.4 Fluorescent Screen......Page 433
53.5 Focusing......Page 434
53.6 Deflection......Page 435
53.7 Time Base......Page 436
53.8 Graticules......Page 437
53.9 Block Diagram......Page 438
Multiple Choice Questions (MCQ)......Page 439
Conventional Questions (CQ)......Page 440
54.2 Preliminary Checks......Page 441
54.3.1 Lissajous Figures......Page 445
54.4 Voltage and Current Measurements......Page 447
Summary......Page 448
Index......Page 449