Ground fault for 50/0.025 CT
Ground fault for 50/0.025 CT
(OP)
How to determine the ground fault pickup (50G) of GE369 Multilin relay for MV motor fused starter unit (300HP) at 4.16kV. The ground CT used for sensitive earth fault detection is 50/0.025 for high resistive grounded systems. What is the method to calculate or determine a threshold for ground current 50G for a MV motor with a 50:0.025 CT?
Thanks
Thanks





RE: Ground fault for 50/0.025 CT
With a ground fault current of 50 Amps you will have a maximum of 0025 Amps to operate the relay.
Are you sure that you have the current rating correct??
Bill
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"Why not the best?"
Jimmy Carter
RE: Ground fault for 50/0.025 CT
The pickup for the GF element in your relay MUST be less than the maximum ground fault value, otherwise it will never see enough current to operate.
It is not a particularly critical setting. We typically start with ten amps, and may adjust either time or current values in the case of nuisance trips.
old field guy
RE: Ground fault for 50/0.025 CT