Protection Engineering Basics and Schemes Protection Engineering | Page 6

5.4.3 Pickup/Drop off Test: ............................................................................................................... 155
5.4.4 Timing Test: .............................................................................................................................. 156
5.5 Different Test Sets operation: ......................................................................................................... 167
5.5.1 Omicron CMC 356: ................................................................................................................... 167
5.6 Voltage Relays ................................................................................................................................. 176
5.6.1 over Voltage Relay (59) ............................................................................................................ 177
5.6.2 under Voltage Relay (27): ........................................................................................................ 180
5.7 Frequency Relay (81): ..................................................................................................................... 184
5.7.1 under frequency Relay: ................................................................................................................ 185
5.7.2 over frequency Relay: .............................................................................................................. 190
Chapter 6 Differential Protection Relay ................................................................................................. 194
6.1 Differential Protection Relay:.......................................................................................................... 195
6.2 Basic laws which Differential Relays follows ..................................................... .............................. 196
6.3 Types of Differential Relays ............................................................................................................ 196
6.3.1 Current Differential Relay: ....................................................................................................... 196
6.3.2 Biased Differential Protection: ................................................................................................. 203
6.3.3 Case 1: ...................................................................................................................................... 205
6.3.4 Case 2: ...................................................................................................................................... 221
6.4 Restricted Earth fault Protection (REF) ........................................................................................... 228
6.5 One Case Study: .............................................................................................................................. 229
Chapter 7
Capacitor Engineering........................................................................................................... 236
7.1 Power .............................................................................................................................................. 236
7.2 Power Factor ................................................................................................................................... 236
7.3 Case Study: ...................................................................................................................................... 238
7.4 Lagging Power Factor: ..................................................................................................................... 241
7.5 Leading Power Factor...................................................................................................................... 242
7.6 Synchronous Condenser ................................................................................................................. 245
7.7 Shunt Capacitor ............................................................................................................................... 246
Chapter 8 Auto reclosure ....................................................................................................................... 248
8.1 Operation: ....................................................................................................................................... 249
8.1.1 Operation cycle ........................................................................................................................ 250
8.1.2 Shots ......................................................................................................................................... 251
pg. 6