online UPS creates noise

[Peter Z]

Hi all!

I would appreciate any help i can get.

I have bad power in my house, voltage is going up and down and drives some of my studio equipment crazy.

So i bought an online UPS (APC Smart UPS RT 2000VA, 230V). The voltage is perfectly stable now but i get a lot of additional noise out of my monitors now. It's not the LF 50Hz hum, it sounds like clicks in a 50Hz rhythm.

If the UPS is loaded with running equipment i can hear that kind of noise also directly from the UPS (no problem - other room). I can also hear it from the power supply from my TOFT ATB24. And of course out of my speakers.

Is this normal?
What can i do?
Is the UPS locted too close at my computer?
Is there some gear (Furman?) solving this problem.

It would be great to get some information. I tried it via "search" but i read that an online 2-converter true sine UPS should cure those problems not creating them.

Thanks for help
Peter

[Audiop]

Sine or not the unit can still radiate a lot of HF.

Try a 10A mains filter or something like that between the UPS and gear.

The HF may travel down the cables as well as thru the air.

edit: I'd like to see more gear on the market with DC input for battery operation or custom outboard PS's.


/Peter

[Thomas W. Bethe]

One thing you can do to local possible noise sources is to take a normal AM radio and detune it so there are no stations present. Then move it around your room as you turn on on off various pieces of equipment. Most UPS systems do not have any thing in them that would cause the types of problems you are experiencing. Lots of household items can cause problems. One big offender is the ignition system for oil furnaces. Another is refrigerators or compressors starting up. Florescent lights can cause what you are experiencing if they are going bad and flickering. If someone on your power line is doing welding it can also show up in the power. Not fun finding the problem and it may take some real detective work on your part.

Best of luck!

[Peter Z]

Thank you Thomas and Peter!

I will try. I'm pretty sure the source of the problem is the UPS. Without it there is only (little) 50Hz humming.
DC inputs would be great but that should be standardized.

[Thomas W. Bethe]

Originally Posted by Peter Z

Thank you Thomas and Peter!

I will try. I'm pretty sure the source of the problem is the UPS. Without it there is only (little) 50Hz humming.
DC inputs would be great but that should be standardized.

Then I would call the manufacture and get it replaced. If it is causing noise in your system it is not doing its job and should be replaced. It could be that there is a serious problem in the unit and you have some arcing or sparking going on and that is NOT GOOD!. Most reputable UPS companies have a toll free number you can call and report the problem and ask for help or a RA to return the unit for check out

Best of luck!.