P54x/EN OP/La4 Operation
(OP) 5-102
MiCOM P543, P544, P545 & P546
OP
In such a stub-end feeding case, relay R2 may experience some overreach in the case of
double-phase to ground faults. This is caused by the unusual current distribution making the
MiCOM P54x detect a single phase fault condition (and potential single pole tripping only in
single pole tripping applications).
For this unusual feeding arrangement, the MiCOM P54x makes available a Zero sequence
stabilizing feature, that measures the dominance of zero sequence current over negative
sequence current (I
o/
2
). It promotes stability by forcing the relay to recognize the above
configuration as a WI condition. It then blocks all distance elements, once the measured I
o/
2
ratio exceeds the setting.
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