Rotor Earth Fault through MiCom p391

You tell me....

http://www.schneider-electric.co.kr/documents/Catalogue/MiCOM_P34x_TechnicalDataSheet.pdf

Please advise the outcome of the telephone calls that have taken place on this topic with the equipment manufacturer and why an answer has not been forthcoming from that source?

It looks like neither of your protective relays detect earthing faults, despite your statement that they are in the rotor earth fault circuit. It may be if you do get an earth fault, the excitation protection may take itself off line, or perhaps float until the next ground fault.

Do both of the existing relays trip off the machine?

Not sure of the value of voltage balance relays, but it could be a good diagnostic tool if your excitation current increased unexpectedly to hold terminal voltage. The relay could indicate turn to turn short circuit in one of the two windings.

From Solar Eagle contribution, thank you....

The voltage balance detection between field windings is not covered in the Micom.

You need a special version of your Micom, and another device to couple to the rotor circuit.

You do get an output from the Micom that can measure some degree of turn to turn faults, not sure if it is connected to an automatic protective function, they pass it to a current loop which then most likely is connected to an alarm, rather than trip.