scheider electric MiCOM P746, Technical Manual

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P746/EN AP/G31 Application Notes
(AP) 6-
2
MiCOM P746
AP
6. BENEFITS OF SECTIONALIZED BUSBAR PROTECTION 23
6.1 Limitation of the number of feeders 23
6.1.1 Bias characteristics 23
6.1.2 Bias current in discriminitative zones 24
6.1.3 Bias current in check zone 24
6.2 Disavantages of busbar schemes with check zone AND high number of feeders 24
6.2.1 Effect on check zone sensitivity 24
6.2.2 Effect of spill current in check zone 24
6.2.3 Contingency during relay / CT failure 25
6.3 Benefits of sectionalized busbar protection 25
6.3.1 Improved sensitivity for check zone 25
6.3.2 Sectionalizing during failure of relays / CTs 25
6.3.3 Simplified topology 25
6.4 Conclusion 25
7. TOPOLOGY 26
7.1 Topology Configuration 26
7.2 Topology Monitoring Tool 27
7.3 Topology processing 28
7.3.1 Single bar or double bus with bus sectionaliser 28
7.3.2 Double bus with one CT bus coupler 29
7.3.3 Double bus with two CT bus coupler 30
7.3.4 CTs on one side of bus coupler 32
7.3.5 CTs on both sides of bus coupler, CB closes before status acquisition. 33
7.3.6 CTs on one side of bus coupler, CB closed and fault evolves between CT and CB
(even for switch onto fault). 34
7.3.7 CTs on both sides of coupler, CB closed and fault evolves between CT and CB. 35
8. UNDERTAKING A NUMERICAL DIFFERENTIAL BUSBAR
PROTECTION PROJECT 36
8.1 One or Three box mode selection 36
8.2 Application solutions 38
8.2.1 1 box mode: 38
8.2.2 3 boxes mode: 38