I have 2 UPS's on site and I'm having problems with one. Now both UPS's are wired the same way but one is flashing the light for ground. I read the troubleshoot guide that came with it and says that there is no ground or neutral and line are crossed at outlet. I checked and everything seems fine. I even followed the ground conections all the way to the transformer and all ground wires are properly bonded. Does this seem like an internal error?
UPS question
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First guess
First guess
My first guess would be that the UPS is detecting an alarm / trouble condition, not a false alarm. It could be finding excess voltage or a loop current between neutral and ground. It's not clear from your post exactly what the UPS says is a problem area.
I would check, as you did, the neutral and grounding back to the source. Also put a sensitive voltmeter, like a Fluke 87, between neutral and ground, line and load sides, and see if the N-G voltage exceeds ~ 0.25 - 0.50 volts. Over 500 millivolt and I would look at the neutral to ground bonding per 250-30, checking line and load sides.
Do you want to try to clarify the UPS alarm code. How big is the unit?
First guess
My first guess would be that the UPS is detecting an alarm / trouble condition, not a false alarm. It could be finding excess voltage or a loop current between neutral and ground. It's not clear from your post exactly what the UPS says is a problem area.
I would check, as you did, the neutral and grounding back to the source. Also put a sensitive voltmeter, like a Fluke 87, between neutral and ground, line and load sides, and see if the N-G voltage exceeds ~ 0.25 - 0.50 volts. Over 500 millivolt and I would look at the neutral to ground bonding per 250-30, checking line and load sides.
Do you want to try to clarify the UPS alarm code. How big is the unit?
checked between n-g with fluke 87 and it didn't go above .5
The unit is being fed from a 2 pole 30A breaker 120/208V panel.
The trouble it is displaying is a flashing light under the ground symbol.
I forgot to mention that this unit has been working for about 2 years and this is the first time it gave that trouble.
The unit is being fed from a 2 pole 30A breaker 120/208V panel.
The trouble it is displaying is a flashing light under the ground symbol.
I forgot to mention that this unit has been working for about 2 years and this is the first time it gave that trouble.
weressl
Esteemed Member
Ungrounded or resistance grounded power supply to the UPS's known to cause problems UNLESS the UPS is specifically designed for such service.
weressl
Esteemed Member
:grin: nevermind me......
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