Over Voltage - because it is cold?

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Old 02-10-11, 06:29 PM
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Over Voltage - because it is cold?

I noticed today that my UPS's report prolonged AVR trim. Checked the logs. Looks like I had for the last two days 130V.

It has bee very cold here in Chicago. Could this be the source of the issue?

Also, how does one report over voltage? Is this considered an outage?
 
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Old 02-10-11, 07:45 PM
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130 volts is not ideal, but it's not too high. You can try calling your power company and see what they say, but I doubt they will do much for you. It's not at all unusual to see 123 or 124 volts on a single phase system. Voltages usually drop down a little around 6 a.m. and slightly rise again around 7 p.m. Mon-Fri as demand on the power companies system increases and decreases. Have you checked the voltage with a known good meter? You may possibly get the power company to send out a trouble truck to check the voltage.
 
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Old 02-10-11, 07:59 PM
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Just pluged in a good voltmeter: 131 V. Very unstable.
BTW. my UPS's are APC SamrtUPS. Very good quality.

According to the UPS log file, the whole things started 2 days ago. Before, it was more like 122 V.
 
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Old 02-10-11, 09:04 PM
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The cold wearher could have loosened the neutral. Ask the power company to check thr connections on their side.
 
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Old 02-11-11, 06:17 AM
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I agree with ray2047. Call the electric company and tell them your findings. Give them the voltages from your UPS logs and when the trouble started. If they don't find a problem on their end have your service panel and wiring checked before a small problem becomes a bigger one. Like ray2047 stated, it could be a loose neutral, which could lead to a dangerous situation.
 
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Old 02-13-11, 06:51 PM
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You may be able to troubleshoot a loose neutral by measuring the voltage between each hot leg and the neutral in the main breaker box. In a correct system, the voltage measured between H1 and N and H2 and N should be basically identical. If there is a voltage difference, there's likely a loose neutral (that should be fixed only by the POCO)
Of course, only do this if you're comfortable working inside your main breaker box.
 
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Old 02-13-11, 06:59 PM
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Thanks for this tip. Could I do this without taking the panel cover off by finding receptacles on both phases and measure at the receptacle?
 
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Old 02-14-11, 12:31 PM
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Yes you could or you could use a 240V receptacle like the type an electric dryer or range plugs in to. The findings are slightly less useful because you cannot eliminate a wiring problem inside your house or main panel, but it is safer to do the measurements with the panel cover on if you feel more comfortable with that.

It is possible your power company was running voltages a little high to avoid blackouts and compensate for the huge demand the winter storm put on the power grid. Has it come back down to normal this week?
 
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Old 02-14-11, 12:49 PM
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I did the test using the receptacles. There was only a difference of +/- 1..2 V.
The voltage is back to about 128V - 129V.
What are the voltage regulations?
 
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Old 02-14-11, 12:55 PM
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That's on the high side of normal; it's usually 120V +/- 5%, but most power companies will push the outside limits to 10% in an emergency situation. In any case, slightly higher is better than lower.
 
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Old 02-14-11, 01:50 PM
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Called the utility to get an update. They came out to measure last week. They got 126V. If I can stay below 130V I should be OK.
 
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