Page 11 - Handbook of Electrical Engineering

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References 308
Further Reading 309

12 Protective Relay Coordination 311
12.1 Introduction to Overcurrent Coordination 311
12.1.1 Relay notation 313
12.2 Generator Protection 313
12.2.1 Main generators 313
12.2.2 Overcurrent 314
12.2.3 Differential stator current relay 318
12.2.4 Field failure relay 319
12.2.5 Reverse active power relay 321
12.2.6 Negative phase sequence relay 322
12.2.7 Stator earth fault relays 322
12.2.8 Over terminal voltage 324
12.2.9 Under terminal voltage 324
12.2.10 Under- and overfrequency 325
12.3 Emergency Diesel Generators 325
12.4 Feeder Transformer Protection 326
12.4.1 Overcurrent 329
12.4.2 High-set or instantaneous current 330
12.4.3 Characteristics of the upstream source 332
12.5 Feeder Cable Protection 332
12.5.1 Overcurrent protection 332
12.5.2 Short-circuit protection 333
12.5.3 Earth fault protection 333
12.6 Busbar Protection in Switchboards 334
12.6.1 Busbar zone protection 334
12.6.2 Overcurrent protection 335
12.6.3 Undervoltage protection 335
12.7 High Voltage Induction Motor Protection 336
12.7.1 Overloading or thermal image 337
12.7.2 Instantaneous or high-set overcurrent 339
12.7.3 Negative phase sequence 339
12.7.4 Core balance earth fault 340
12.7.5 Differential stator current 340
12.7.6 Stalling current 340
12.7.7 Limitation to the number of successive starts 341
12.7.8 Undercurrent 341
12.7.9 High winding temperature 342
12.7.10 High bearing temperature 342
12.7.11 Excessive vibration 342
12.8 Low Voltage Induction Motor Protection 342
12.8.1 Overloading or thermal image 343
12.8.2 Instantaneous or high-set overcurrent 344