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Posted: 2021-06-2807:27 AM
Back-UPS 700 shutdown followed by continuous beep, no light
This was originally posted on APC forums on 10/5/2018
Hi, i have a Back-UPS 700 from APC, that has been acting up for the last few months.
I live in a village and our power isn't the most stable, probably because of weak infrastructure and power hungry machines being used by my neighbors, like home made welders, milking machines, etc.
So when the voltage drops below 215V the UPS kicks in, not to battery mode, but probably some kind of voltage regulator or protection (i can hear the relay click) and then it switches back to normal once the voltage passes 215V.
The problem comes when the voltage varies too fast for the UPS to keep up, this is my guess, because if it changes slowly the UPS has no problems. When this happens the UPS switches the power off to my PC, shutting it down, gives a continuous beep and there are no lights showing. It continues to beep until i shut it down by holding the power button for a few seconds, a quick press does nothing.
I'm thinking there might be something wrong with the relay, switching to fast might cause it to get stuck, probably half way, because the power stops flowing to my PC.
Or it could be something else, because when a relay switches it causes little power surges, these in quick succession could build up and overload something or who knows.
Frankly the UPS switching between normal and power regulation via relay just because the voltage changes from 214V to 216V and back is a design flaw. Lowering that threshold to 200V would help, my PC runs fine on 200V, or delaying how fast it switches back would also help, or not using a relay to do the switching.
I even bought a dedicated automatic power regulator to help with these issues, and while it happens less often, it still happens (unfortunately it also uses relays to do the switching, which probably causes little micro-surges that the UPS reacts to), i can also (very rarely) hear popping sounds sometimes coming from my speakers exactly as the switching happens.
I would stop using both of them, but i can't since we also get pretty regular power outages (for a while it was daily)
I read other posts before writing this, some said that the battery might have a poor connection or be disconnected, i don't think that is happening in my case since if i unplug the UPS from the mains it switches over to battery mode and my PC keeps running for quite a few minutes.
Another post said something about ground to neutral voltage, i measured that and it's at 0V.
It's also not being overloaded as this kind of thing happens even if the computer is off.
I would also like to mention that the UPS worked fine for the first 6-9 months after we moved here. This is why i suspect it's a relay issue, it got worn out or something from all that switching.
Unfortunately because it's such an intermittent issue i can't send it into warranty, they would just send it back saying it's fine. (they actually sent me back a different brand UPS with a dead battery saying it was fine, because i didn't know what the exact problem was so i didn't describe it accurately)