Voltage relay for ground fault

[rwalker1]

I've run into a situation where a new customer wanted me to test his ground fault relay. After servicing the high pressure switch and beginning to set up my test equipment I noticed that the relay's control power wiring had been removed and taped. In addition the relay's current pot had been turned past the maximum setting. It was Saturday and I've seen plenty of ground fault relays unhooked to prevent "nuisance tripping" and the adjustment being turned past max supported my theory. With no wiring diagram or clear indication where to land the control wiring I could not test the relay. Due to the expense of downtime and my recommondation, I order them a new relay to test and install.

Return to site for another issue prior to the new relay arriving and end up at the incoming substation. Low and behold the 13.8 to 480 delta wye transformer has nothing on the Xo bushing. Ooops. So now the relay I've ordered is useless. Start looking around, this forum and others, and the use of PT's for ground fault protection in an ungrounded system is frequently discussed. Now it occurs to me that there was a Taylor phase guard relay (basically an anti single phase relay). Could this have been someones solution to the problem? If so, how good a solution was it?

Sorry if a bit long winded.

 

[waross]

The Taylor phase guard is a loss of phase detection device.
It does not have a ground connection shown on the wiring diagram so it will not be able to detect ground faults by itself.
With three PTs connected grounded wye on the primary a ground fault on the primary would show up as a phase loss on the secondary. That is the primary and secondary of the PTs, on the 480 volt system. NOT the 13.8 primary of the main transformer.
See
taylorphaseguard.com/id14.htm
Even though the X0 is not connected, you may have a set of grounding impedances somewhere that connect to the relay.
respectfully

 

[rwalker1]

Thanks,

I think I need a closer look at how the Taylor is wired. Just to determine if it is just there for phase loss (another useless relay I suppose) or if someone has done something more creative.

 

[moreause]

some relay, fpe kind (bought by ipc..anf now guard something)

don't need the xo, they kind of make there own xo(with resistor) and use phase to ground voltage to decide if there is a fault

but personnaly if your costomer has an xo...maybe it would be tiem to sell a resistor...after that it will become a bit easier to find the fault without putting some power off