Ground Fault Relays on HRG Systems 2

[nightfox1925]

I read an article regarding application of HRG systems. It is true that one of the main advantages of an HRG system is to locate a first ground fault without shutting down the system. In addition, if a second ground fault occurs, it will initiate a trip. If a second ground fault occurs, wouldn't it be likely similar to a phase to phase fault since, two phases will be commonly connected to ground? will this current be enough to trip the phase overcurrent relays? If the second ground fault is away, will the ground impedance be significant to limit the fault? The article says something about setting the gorund fault relays above the system charging current, what does this mean? If an HRG system is applied to a particular system, are individual ground fault relays still required?

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[davidbeach]

Look for the paper Negative Sequence Relaying Applications in Ungrounded and High Impedance Grounded Industrial Systems at

http://www.basler.com/html/dwntech.htm#negseq.

It may well answer you questions plus a bunch more you haven't asked yet.

 

[nightfox1925]

Thanks david, I'll take it fro here. The link is very informative.

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