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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