SUA1500 - Faint short buzzing/cicada-like noise every 30-60 seconds?

[Anonymous user]

Hello,

I've just changed from a 700W simulated sine-wave UPS and a no-PFC 500W PSU to an active-PFC 850W PSU and acquired a Smart-UPS 1500VA, which is pure sine wave.

The first difference I noticed is that the fan is always on, but I've read these later models are supposed to be that way, so no problem then.

However I've also noticed that about approximately every 30-60 seconds there's an odd buzzing noise which pitch resembles that of a cicada's and only lasts for a second. It seems to be coming from the rear of the UPS. The PSU itself also seems to make the same sound on some occasions, but not always. The UPS will make the sound even when the PSU and monitor are switched off.

PSU is Corsair TX-850W and monitor is T220 - 45W.

UPS Led status tells me it's On-Line and when I do the Diagnostic Utility Voltage Feature it gives me 4 LEDs. I've read in manual 3 is normal and 5 requires the line to be checked by an electrician. Is 4 considered normal or bad?

So far I've just been assuming this is normal for these more complex electrical equipments and perhaps it's also the first time I've noticed them because this PC is more silent than my older one, but I'd like if someone here could confirm it nonetheless.

As I've said this is not a constant or continuous loud sound, but short and faint and is heard about every 30-60 seconds.

Can I consider this normal or not?
Thanks in advance

[Anonymous user]

Hello,

I've just changed from a 700W simulated sine-wave UPS and a no-PFC 500W PSU to an active-PFC 850W PSU and acquired a Smart-UPS 1500VA, which is pure sine wave.

The first difference I noticed is that the fan is always on, but I've read these later models are supposed to be that way, so no problem then.

However I've also noticed that about approximately every 30-60 seconds there's an odd buzzing noise which pitch resembles that of a cicada's and only lasts for a second. It seems to be coming from the rear of the UPS. The PSU itself also seems to make the same sound on some occasions, but not always. The UPS will make the sound even when the PSU and monitor are switched off.

PSU is Corsair TX-850W and monitor is T220 - 45W.

UPS Led status tells me it's On-Line and when I do the Diagnostic Utility Voltage Feature it gives me 4 LEDs. I've read in manual 3 is normal and 5 requires the line to be checked by an electrician. Is 4 considered normal or bad?

So far I've just been assuming this is normal for these more complex electrical equipments and perhaps it's also the first time I've noticed them because this PC is more silent than my older one, but I'd like if someone here could confirm it nonetheless.

As I've said this is not a constant or continuous loud sound, but short and faint and is heard about every 30-60 seconds.

Can I consider this normal or not?
Thanks in advance

[BillP]

do you have a voltmeter? its just indicating that your voltage is a little bit high, maybe around 123ish rather than 120. if it was a dangerous level, the UPS would be using its automatic voltage regulation to trim the incoming voltage or if it was severe enough over voltage, the UPS would go to battery - so no need to worry.

you're right - the fan is always on with newer models - there are two speeds.

the UPS should not make too much noise when it is online. i am not sure what the noise you are describing sounds like though haha. i would make sure nothing is caught in the fan just incase even though i dont think its that type of noise.

also, you said the UPS makes it even if the equipment is off but how do you get the noise to stop on the UPS? if you turn it off does it still do it or do you need to remove the battery (or braindead the UPS - turning it off, unplugging from AC power, holding down off button for 5-6 seconds) to get it to stop? dont know if you have tried that.

[BillP · Accepted solution]

In regards to the site wiring fault LED, if you arent sure, it indicates one or more of the following:

-overloaded neutral
-reversed polarity
-missing or loose ground

overloaded neutral and reversed polarity could be checked by anyone with a voltmeter. missing or loose ground might require an electrician to check the wall outlet and take it apart, etc

i dont think a buzzing would be caused by this but i am not 100% sure - maybe electrical noise or "pings" coming from the power company. i know they do that here in the US and maybe there is something similar in your location. the power company monitors the power lines but it would also i believe cause the UPS to go to battery.

the UPS stops charging the battery when it hits 100% but then switches to a trickle charge thereafter to keep the battery at a float voltage.

i am not sure why the voltage would change from 230-240v perhaps if something on the same circuit was drawing more or less current (like a refridgerator, etc) it could affect the voltage on the circuit or maybe it has to do with something on the power company's end.

i cant hear the buzzing noise at this point because the website is blocked here but i will try to listen to it later. overall, the UPS should make a slight hum but it really shouldn't be that noticeable. it is fairly noticeable when the UPS is running on battery from experience which is when you AREN'T hearing it. i will have to check the link to be sure.

[Anonymous user]

The only hum I can hear when standing nearby are the fans, but those I don't notice from where I am - 1 meter away. Only the periodic buzzing noises coming from the power outlet connected to the UPS on the rear.

These can be heard even from 4 meters away due to their high frequency. I've actually noticed PSUs of older PCs in the house do the same thing after all, but it's not as loud or frequent. Maybe it's because they draw much less power than the one I'm currently using.

Perhaps it has indeed have something to do with the voltage in my house or from the electrical company. So I think even if I changed unit it would do the same thing. I'll just have to get used to it or try to contact an electrician just to be sure everything's fine on my end.

Edit: Something interesting to take note: right now I don't seem to be hearing the noise from where I am, but did 1 hour ago, so I've decided to check out PowerChute. Turns out 1 hour ago the line voltage was 240 and it's 236 at the moment. Could this mean the buzzing is being caused by the high voltage? Or maybe it's the UPS re-adjusting output voltage each time the line voltage changes?

Edit2: Hmm nevermind. It has been 236 for quite some time and it's doing it again. Seems random after all.

Thanks once more!

Message was edited by: Asclepius89

[Anonymous user]

Reviving old thread I know, but having a concern which may not be. Have had my macbook and speakers connected to my DLA/SUA1500 for the past couple of weeks, noticed the fan humming noise right away, everything sounds great. and working as it should.

Received my new Imac today, Plugged it in and a new intermittent, high pitch noise started above the usual hum I've been hearing all week. Definitely from the UPS and not computer or peripherals. could last for 10-30 seconds, disappear for a few seconds and then come right back. Any type of computer inputs can set it off or stop it, such as changing a web page, placing my curser over the program dock, etc

Far be it for me to diagnose the problem, but it really does seem like a radio frequency interference. The UPS is probably about 3 feet away from the Imac. No warning lights are illuminated. I can put up with the noise, but would just want to know that everything is working as it should.

Any input would be appreciated.

[Anonymous user]

I just saw this thread and wanted to comment on it. My UPS has exactly the same problem -- a faint "cicada" noise every 30-60 seconds. My UPS is branded as an IBM UPS 750T, but it is made by APC. I bought it used and it has always had that problem. It works fine otherwise. Mine sounds identical to the previously posted audio file. However, my UPS does not always make that noise. I will notice it for a few days and then I won't hear it for some time after that. It has nearly new batteries and I have checked the site wiring.

I am also having problems with RF noise coming from this unit, but I will post that in a separate thread.

-Nelson

[Anonymous user]

Apparently this noise issue is very common on many UPS.

I got a used APC Back-UPS NS 1250 (BM1250LCD) and it makes this high pitch buzzing/whine every several seconds once the battery is fully charged. So, I assume it is the trickle charge that is causing this issue.

I have tested the batteries and they are fine. I get plenty of run time I have checked the batts with a  meter and they check out fine.

This noise is so annoying to me. I does it even when nothing is plugged into the UPS.  I had to remove the UPS it was bugging me so much.