UPS and Noise

[rrezende]

Hello.

I've just bought an UPS (Uninterruptible Power Supply) and I'm new in this stuff.

What I'm worried is that this UPS makes some sort of "huming" noise when it's turned on (like mmmmmmm). I know it's supposed to make noise when it's working without AC current, but should it make noise when it's not running its batteries ?
This noise gets a bit irritating, specially at night. Could this be a faulty unit ?

The light indicators show everything is fine and it indeed works fine when the power goes out.

The manufacturer is APC but the model is only available in Brazil, so don't bother looking for it.


Thanks.

 

[Horsepower]

My APC unit makes a humming noise when others in the house are using heavy electricity. You may want to check if your incoming voltage is within specs.

 

[rrezende]

Maybe that's the problem. When it's working on AC power, the light "Voltage Regulation" is always lit. Probably the voltage is not exactly within specs. Our electrical company is notorious for their suboptimal service.

Anyway, APC returned my e-mail and they said that all noise is fine if it's below 50dB at the distance of 1 meter. I believe it is because 50dB is quite high (sound of a normal conversation, I guess).

Thanks for your reply.