Figure 48: Current Distribution In An Insulated System With C Phase Fault - GE P24DM Technical Manual

P24xM
E00627

Figure 48: Current distribution in an insulated system with C phase fault

The figure above shows the relays on the healthy motor feeders see the unbalance in the charging currents for
their own feeder.
The relay on the faulted feeder, however, sees the charging current from the rest of the system (IH1 and IH2 in this
case), with its own feeders charging current (IH3) becoming cancelled out. This is further shown by the phasor
diagrams in the next figure.
P24xM-TM-EN-2.1
IR1
IR2
IH1 + IH2 + IH3
IR3
IR3 = IH1 + IH2 + IH3 - IH3
IR3 = IH1 + IH2
Chapter 6 - Current Protection Functions
Ia1
Ib1
jXc1
IH1
Ia2
Ib2
jXc2
IH2
Ia3
Ib3
jXc3
IH1 + IH2
IH3
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