UPS trouble breakthrough

[Dorkenstein]

I figured out how to switch the UPS to low sensitivity without an interface cable. It's a 5 year old APC BX1500 (Back UPS XS). Now when the alarm used to freak out, it stays silent. I couldn't hear this before due to the alarm, but I can hear my PSU make an audible buzz every so often. I think this is what used to set off the UPS alarm. At least, it sure sounds like the buzz is coming from the power supply. My power supply is a Silverstone Decathlon 750w modular psu.

I guess now I need to find out what this noise is, and if I need to replace my PSU. Thanks for any more ideas.

 

[Itchrelief]

Buzzing is probably when the system it switching to inverter simulated sine wave. Supposedly this type of waveform can cause some resonance in the PSU components. I hear the same thing whenever my UPS kicks in, but in my case the UPS also makes the same noise but louder than the PSU. I believe this is just a normal side-effect of using non-sinusoidal power. You aren't going to get around this unless you pay megabucks for a true sine wave UPS or find a PSU that has fully potted internals (do these even exist?).

It was probably doing the same thing before but you never noticed it. As long as it's an infrequent, short-term occurrence, I wouldn't worry about it. If it is more than that, I would guess your problem is probably either in your electrical supply/wiring or the UPS itself rather than the PSU (but I am a mere user, not an engineer), as this means your UPS is switching to battery very often, so either your power is very spotty or your UPS is switching more than it should.

 

[Dorkenstein]

It makes the noise pretty frequently, which probably isn't good. Thanks for your informative reply.