SUA1000 'buzzing' concerns

[Anonymous user]

I just got a refurbished unit, Smart-UPS 1000 (600W) UPS and attached a new Dell to it. For 3 days it ran fine. Then it started to make noise, and it concerned me. I turned off all the attached loads and it didn't stop? I had to unplug the unit from the wall to make it stop. The next morning I plugged it back in, reattached only the System unit. Ran fine for a day and the noise returned. It is NOT constant, but it can go on for quite awhile, from minutes to hours.

I've put my ear right one the ventilation holes on both sides of the case and it sounds like it is coming from the rear. Looking at the unit, the top right rear appears to be 'warmer' than the rest of the case.

The 'noise', tough to classify and at times it sounds slightly different.

At times I've heard :

-- Buzzing, loud enough to be hear from 12 feet away, very fast too at a constant rate.
-- Zapping, almost like an electrical discharge, constant rate.
-- Clicking, almost like a telegraph key putting out the same key over and over again, somewhat lower than the other 2 sounds.

Is this dangerous?

Is this 'normal' for these types of UPS's?

This unit is in a home as the Dell has a PFC PSU and required it seems a strict pure sine wave to hold power when it is on battery power.

I have other APC UPS's in the house, all BACK-UPS, and none exhibit this problem.

The unit does have a warranty, but I'd like to know if it is bad or not? Supplier tells me this is 'normal' for these UPS's.

Thanks in Advance,
Irv S.

[Anonymous user]

The SUA1000 is one of our more popular UPS we use and it is a very dependable unit. It is normal for it to make the buzzing noise during the initial boot or returning from being on battery. I would recommend making sure all of the battery terminals are secure so you are getting a good connection.

[Anonymous user · Accepted solution]

First thing I did was check that. I've only had it for a little over a week and it was shipped with the back connector in as well as the battery?

It is in a home, air conditioned room and the noise generally is at night or late afternoon. If it were using battery power I would expect to see from panel indicators on, but they are not?

APC tells me to trade it in, but I've contacted the supplier. At first they told me it wasn't a problem, but the noise is to me. They are replacing it.

I figure if the noise was normal, someone would tell me it is, but I can't see any messages indicating it is normal. The 'arcing' sound was the really worrisome one, I was afraid of heat and a fire. Clicking I can handle, but the buzzing is way too loud... hope the next one works better. If it doesn't, I don't know what I'll do?

Irv S.