Generator starts due to high voltage

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Mr. Wizard

Senior Member
Location
Texas
Happy early Thanksgiving everyone...please be safe. For the second time this week we've had a generator start up due to higher than normal voltage. We have two direct feeds to our facility from the poco, and the poco has a transformer vault on-site, where the high voltage is stepped down for our use. I've taken many voltage readings throughout the facility, and we're running a little "hot", meaning our nominal voltage between phases fluctuates between 490 to 503 volts. Our ATS's automatically fire the generators when poco voltage hits 528 volts, and the info from the data screen on the ATS's indicate that was the problem both times. My director called in Holt and their conclusion (which was the same as mine) is we need to get the poco involved in this to see why the incoming voltage is so high. My director disagrees and believes that Holt needs to fix the issue. Anyone out there have any similar issues in the past? Thanks in advance for any info
 

mivey

Senior Member
While there may be times that the voltage does go that high, twice a week is too often. How often has this happened in the past? The POCO needs to come across with an explanation or assurance that this is a highly unusual event.

Definitely the POCO needs to be involved. Be sure to look to them as someone to help, not as an adversary.
 

bob

Senior Member
Location
Alabama
Get the utility involved. They can change the taps on your transformer. They may also have
capacitors on line that is raising your voltage. Call them now.
 

Haji

Banned
Location
India
In rural areas such high voltage problems usually arise, as the POCO deliberately rises the supply voltage to compensate for the voltage drops in their lines, but during the low load condition, the voltage rises above normal. So there may be large load shut down upstream in your case and also presence of capacitors on the lines would aggravate the voltage rise problem.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
I fourth it...
Call the poco.

Taps as bob said, or regulator issue, in which case a bunch of customers would be affected.

We run ours a little hot, that would be 511/295. Yours is a lot hot. exceeding 10% is too much
 
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