2.3.1 Series Sealing:............................................................................................................................ 67 2.3.2 Shunt Reinforcement:................................................................................................................ 68 2.3.3 Shunt reinforcement with sealing:............................................................................................. 69
2.4 Trip circuit Supervision:.................................................................................................................... 69 2.4.1 H4 Trip Circuit Scheme:.............................................................................................................. 70 2.4.2 H5 Circuit Scheme:..................................................................................................................... 71 2.4.3 H7 Circuit Scheme:..................................................................................................................... 72 Chapter 3 Engineering Drawing............................................................................................................... 73 Chapter 4 Symmetrical and Unsymmetrical Faults................................................................................... 95
4.1 Short Circuit Faults:........................................................................................................................... 95 4.2 Symmetrical three phase Fault:.................................................................................................... 95 4.2.1 Symmetrical Components.......................................................................................................... 97 4.3 Phase to ground fault........................................................................................................................ 99 4.4 Phase to Phase Fault....................................................................................................................... 103 4.5 Double phase( Phase to phase) to ground faults............................................................................ 105 4.6 Three phase faults........................................................................................................................... 107
Chapter 5 Protection Relay.................................................................................................................... 109 5.1 Operation........................................................................................................................................ 110 5.2 Terminologies used in Protection Relay:........................................................................................ 111 5.2.1 Plug multiplier setting.............................................................................................................. 111 5.2.2 Time multiplier setting:............................................................................................................ 112 5.3.1 Definite Time Relay.................................................................................................................. 112 5.3.2 Inverse Time Relay................................................................................................................... 113 5.3.3 Instantaneous Relay:................................................................................................................ 119 5.3.4 Relay connection Figure........................................................................................................... 121 5.3.4 Directional Overcurrent Relay................................................................................................. 122 5.3.5 One Case Study( Protection Relay-OC-Setting)........................................................................ 135 5.3.5 Case study # 2:.......................................................................................................................... 139 5.3.6 Case study # 3:......................................................................................................................... 141
5.4 Testing of Protection Relays:.......................................................................................................... 144 5.4.1 Pickup Test:.............................................................................................................................. 144 5.4.2 Drop Off Test:........................................................................................................................... 155
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