GF relaying on parallel off grid generation

[eaglebeak]

Have multiple generators on off grid system. All generators are 2400/1385 wye with hard ground and ground fault relaying.

When running two or more units in parallel (there are 6 units total, dispersed over several miles) do I need to transfer trip any ground fault relay action from a running unit to the the other running units?

Each unit is earthed individually. The connecting distribution system is 2400v three phase, three wire.

Three of the generating units are 480 volt delta with a close coupled 480/2400 wye auto transformer with center grounded.
The other three generators are wound 2400/1380 wye and similarily grounded.

 

[Marmite]

You really need to post a single line diagram to get a meaningful answer. Protection systems should be set up to trip the minimum amount of plant necessary to clear the fault.

Regards
Marmite

 

[TurbineGen]

It depends on the location of the fault. You might in fact need to block a trip from the unfaulted generator(s) to keep them from tripping. As Marmite said, you typically want to trip as few units as possible. If the fault is on one machine, I would think you would only want to trip that one machine. You would want a transfer trip only in the event of a breaker failure.

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