Hopefully this is the right place to ask.

I have an APC Back-UPS XS 1400U that I use to keep my home server running 24/7.

It was purchased in 2015, batteries replaced around 2020, everything was fine until around June 2023 when it started randomly switching to battery for a few seconds for no apparent reason once or twice a day.

The UPS is connected to my home server via USB so I can get some readouts. It says “Unacceptable line voltage changes”, but it’s configured to switch when it’s outside the 160-280v range and it gets nowhere near those thresholds, the voltage fluctuates in the 224-234 range.

I connected an oscilloscope to the mains to see if there were transients when the problem occurred but I don’t see anything out of the ordinary and the problem has been getting worse, now it switches an average of 50 times a day.

The UPS still works, it can keep the server up for hours if I unplug the power, so the batteries should be good. What’s going on?

  • UnlimitedRumination [he/him]
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    1 year ago

    How did you identify the problem and get ComEd to look into it? My UPS is switching inconsistently, sometimes a couple times a day, and I’ve seen some signs that makes me think it’s not just that UPS/outlet/breaker. I wasn’t at the point where I was going to do anything yet but since you’re talking about the same provider I have I figured I’d ask. I have a multimeter, oscilloscope and smart plugs that watch voltage/amperage/power.

    • @glimse
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      31 year ago

      We didn’t actually identify the problem at all! My boss had the electrical knowledge and couldn’t find anything wrong with the line. But as for contacting ComEd, I never had to call them myself but I’m sure he has some special industry phone number he can call for that sort of stuff. Or at least knew someone who did, he has tons of friends in every trade