ABB REL 356

ABB REL 356 Current Differential Protection
4-11
Measuring Elements and Operational Logic
Figure 4-9. Mho Characteristic for Three Phase Faults
Phase to Phase
The phase to phase unit responds to all forward phase to phase faults, and some phase to phase to ground faults. The
operating and reference quantities are:
OP = (V
AB
– I
AB
Z
P
)
REF = (V
CB
– I
CB
Z
P
)
Figure 4-10. Mho Characteristic for Phase to Phase Faults