ABB RELION 670 Series Applications Manual page 9

6.1.3.9 CT disconnection for bus section and bus coupler current transformer cores...............102
6.1.3.10 End fault protection..................................................................................................................... 107
6.1.3.11 Zone interconnection (Load transfer)......................................................................................109
6.1.3.12 Tripping circuit arrangement......................................................................................................113
6.1.3.13 Trip arrangement with one-phase version...............................................................................113
6.1.3.14 Centralized trip unit......................................................................................................................114
6.1.3.15 Decentralized trip arrangement.................................................................................................114
6.1.3.16 Mechanical lock-out function......................................................................................................114
6.1.3.17 Contact reinforcement with heavy duty relays....................................................................... 115
6.1.3.18 Trip circuit supervision for busbar protection........................................................................ 115
6.1.4 Different busbar arrangements.....................................................................................................115
6.1.4.1 General.............................................................................................................................................115
6.1.4.2 Single busbar arrangements.......................................................................................................116
6.1.4.3 Single busbar arrangements with sectionalizer..................................................................... 116
6.1.4.4 Single busbar arrangements with bus-section breaker........................................................ 117
6.1.4.5 H-type busbar arrangements..................................................................................................... 118
6.1.4.6 Double circuit breaker busbar arrangement........................................................................... 120
6.1.4.7 Breaker-and-a-half busbar arrangements................................................................................121
6.1.4.8 Double busbar single breaker arrangement............................................................................123
6.1.4.9 Double busbar arrangements with two bus-section breakers and two bus-coupler
breakers.......................................................................................................................................... 129
6.1.4.10 Double busbar-single breaker with transfer bus arrangements.........................................130
6.1.4.11 Combined busbar arrangements............................................................................................... 131
6.1.5 Summation principle....................................................................................................................... 134
6.1.5.1 Introduction................................................................................................................................... 134
6.1.5.2 Auxiliary summation CTs.............................................................................................................136
6.1.5.3 Possible ASCT connections for REB670....................................................................................137
6.1.5.4 Main CT ratio mismatch correction...........................................................................................139
6.1.5.5 Primary pick-up levels for summation type differential protection .................................. 139
6.1.5.6 SLCE 8/ASCT characteristics for end-connection..................................................................141
6.1.5.7 SLCE 8/ASCT characteristics for series-connection............................................................. 142
Section 7 Current protection...............................................................................................145
7.1 Four step phase overcurrent protection OC4PTOC(51/67).........................................................145
7.1.1 Identification.....................................................................................................................................145
7.1.2 Application.........................................................................................................................................145
7.1.3 Setting guidelines............................................................................................................................ 146
7.1.3.1 Settings for each step................................................................................................................. 148
7.1.3.2 2nd harmonic restrain..................................................................................................................150
7.2 Four step single phase overcurrent protection PH4SPTOC (51).................................................155
7.2.1 Identification.....................................................................................................................................155
7.2.2 Application.........................................................................................................................................155
7.2.3 Setting guidelines............................................................................................................................ 156
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