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?
Oh man I went through this a few years ago…though I doubt it’s the same problem.
I was a custom integrator and one of my clients had a beeping UPS. Unstable incoming voltage. Ok, not the first one of these to kick the bucket so I do the RMA.
Later that same week I’m at a different client for the same thing. Call my boss and tell him we should start looking at other manufacturers, he agrees.
RMA arrived and I install it. Later that day the client calls…the beeping is back. I call my boss and he’s at yet another house dealing with the same thing.
“Wait…you’re at [client]'s? That’s a few blocks away. And so are [other 2 clients]. Are we sure it’s the UPS…?”
TURNS OUT IT WASN’T! There was something fucky with the neighborhood grid (the transformer? node? I don’t know, I’m not an electrician). We talked to ComEd, they and a few weeks later they did some repairs. No more problems.
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.
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