Are UPSs Supposed To Hum?

[geno]

I just had some weird power fluctuation here and my UPS switched to its battery. It began humming (and electrical buzz kinda). Is this normal? It seemed to be working fine as far as supplying my PC with power, but I never owned a UPS before, so I didn't know if it was supposed to buzz like that.

 

[dkozloski]

Maybe it doesn't know the words.

 

[NaughtyusMaximus]

I have one that does hum both when it is charging the battery, as well as when the battery is powering the unit. To know for sure about your unit though, you should probably make note of the model number and manufacturer.

 

[oldfart]

Yes, they will hum. That is the inverter. To convert from DC to AC, an oscillator must be used. That is what causes the noise.

 

[arthurb1]

I will interfere with poorly sheilded speakers too...or if the UPS is poorly sheilded. My old TrippLite POS used to do it all the time (switch to battery then back)...my new APC doesn't as mach (only like 2 times in the last 6 months that I have had it) and never hums when the battery is charging.

 

[damien6]

Some older ones do depending on the make/model but most of the newer ones I've seen don't hardly make any noises.

I picked up a Belkin 650 w/USB and it only makes beeping noise when booting up but other than that it's pretty quiet (dead silent).