winding differential relay
winding differential relay
(OP)
Anyone knows the compatibility features of 87GD (generator ground-differential relay) and 67N (ground-directional overcurrent)?
Base on the single line diagram, 87GD is connected to the generator; but on the panel installation it is a 67N instead of 87GD relay. This set up is operational.
I am just wondering how can this be? I keep on reviewing the manual about this relays and im convince that this relays are not alike, interms of protection scheme.
Or maybe im misleaded with my conviction, does anyone had an experienced like this?






RE: winding differential relay
RE: winding differential relay
RE: winding differential relay
This is used where the Generator connects directly on to the Distribution network without a Delta-Star Step up transformer, and no differntial protection is available.
The directional element discriminates between System Earth Faults, and Faults on the generator, therefore eliminating the need for a delay.
If you have Differential protection, or a Delta/Star transformer this is not necessary.
RE: winding differential relay
Differential protection might not cause an operation, however a 67N using a Voltage Operated Earth Fault relay could detect the faults not seen by the differential protection.