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Home » Spaces » Racks, Rack Accessories, & Cooling » discussion » General » New Smart UPS Lcd 1000 buzzing noise every 20 seconds.. is it normal?!?

New Smart UPS Lcd 1000 buzzing noise every 20 seconds.. is it normal?!?

Discussion in Racks, Rack Accessories, & Cooling started by Alessio , 5/9/2012 8:03 AM
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  • alessio1726
    New Member New Member
    Alessio 5/9/2012 8:03 AM

    last week I have purchased a new 1000va SMT Lcd; before I used a backups 1000 APC and there wasn't strange noises.
    I have attached a audio file, or it is possible to hear here:

    When the batteries are at 100%, this noise start and it's go ahead every 20 seconds (you can hear it at the start of this audio file and 2 times after around 20 and 40 seconds).
    It is possible to hear it also when the smart UPS is off, but with the current attached.
    This isn't the normal sound of the batteries, I have recorded it at 30 centimetres; If I accosted my ear, I can hear the normal batteries works.
    Another strange thing, sometimes there are loud noises when the smart UPS works, type sputtering, but it is one time every one or 2 hours.
    The same thing when it is off, WITHOUT current.. even after 2 or 3 hours which is turned off; but I repeat, it is only a noise and stop.. but loud enough to wake me up..
    My backups didn't produce these sounds.

    Is it a normal sound? (every 20 seconds)
    And the other sounds?

  • kulot
    =S= Representative
    Bernard 5/9/2012 3:30 PM (in response to Alessio)

    Good day!</br> <img width="50"> Can you provide the exact model number of the UPS? What I'd suggest is to de-energize/brain dead the unit, by doing so, you are expelling electrical charges that may be stuck in the capacitors of the unit, it's like a hard reset. </br>1. Turn the UPS off </br>2. Unplug the UPS from the wall outlet</br> 3. Disconnect the battery and leave it disconnected for 10-12 seconds.</br>Reconnect the battery, plug it back into the wall outlet, turn it back on and check if you can still hear the noise.

  • alessio1726
    New Member New Member
    Alessio 5/9/2012 8:06 PM (in response to Bernard)

    the model is APC Smart-UPS 1000VA LCD 230V

    I have received it 10 days ago and the model is new, the battery is tested in date 01/02/2012.
    I have tried to disconnect the battery, following your points:
    for one hour the noise is disappeared, but after I have heard a PACK! like a little outbreak and the buzzing noise is comes back.. and it continues every 20 seconds..

    Message was edited by: alessio1726

    Message was edited by: alessio1726

  • Ironbuket
    Novice Novice
    John 1/9/2018 9:35 AM (in response to Alessio)

    Hi, I have exactly this noise and behaviour on my SMT1000i which I only bought a few weeks ago. Did you ever find out if it was a fault or something normal?

    I found that if I shutdown the UPS via the display and turn it off at the mains. Then mains back on and UPS back on, the sound will not be present anymore until the UPS is put under load. The sound occurring every 20sec then continues even when the load is later removed.

    The online audio example you provided is the second example Ive found exactly matching what Im experiencing so that makes at least 3 of us. Im starting to think it may just be normal, but Im trying to check a bit more before I resort to moving the UPS to somewhere I wound hear it less.

  • wpasquil
    =S= Representative
    Bill 1/9/2018 5:47 PM (in response to John)


    Sorry for the inconvenience. The noise in the audio is not normal behavior. The unit will hum when the battery is charging and when under load but that would be a constant hum not intermittent. 

    Please feel free to contact local support if you think the unit is not performing properly and they will assist with trouble shooting and if needed provide a replacement. 

  • Ironbuket
    Novice Novice
    John 1/10/2018 12:12 PM (in response to Bill)

    Thanks for the offer of support, unfortunately my unit is refurbished so my warranty is with a third party and not APC. The more I investigate this sound the more it begins to look like it may be normal behaviour of the UPS. Normal in the sense that the unit isn't faulty, not normal in the sense that every user would hear this sound. I found another case of someone experiencing this sound where they exchanged their new APC unit twice (so had 3 new units) and all made this sound. A comment made by someone over on Amazon reviews suggested the sound might be due to problems with the mains voltage (ie sounds associated with the UPS correcting). I have to get my mains supply checked but one of the questions asked of that person during their conversation was are you near a substation and in my case I am very near a substation. I also found another case where a unit was sent back and testing found nothing wrong - not a very scientific conclusion but you wouldnt expect anything to be found wrong if the issue was caused by the mains supply?

    I could cold connect my UPS to the mains (display off) and leave it that way all day without a peep. I can turn the UPS on and apart from the noise from the start up test it will still sit there not making any sound at all. It is only after something connected gets turned on and it receives a load that the repeating sound begins. I noticed last night that even after I shut down the UPS (but still getting mains power) the repeating sound continues.

    NB: I realise I may not get help for this on the forum, but Im putting up what info I do know as a resource for others that might experience this issue and go searching the net. There are very few reports that can definitely be matched to this specific sound and none of the cases I found (so far) ever had a satisfactory conclusion. It was only by searching for '20 seconds' that I found this one and there are plenty of complaints about hum, coil whine and transformer buzz etc to make picking out cases related to this sound particularly difficult.

    UPDATE: I discovered something interesting this morning. Starting with the UPS off + wall power off. Turn on the wall power and leave it that way for a few mins. Turn on the UPS display and again leave it a few mins. When load was applied after that the 20sec repeating sound did not occur whilst the UPS was in operation under a load of around 25% After a couple of hours there was a noise like a solinoid and the repeating sound began. This occurred just after I had put some more load on it (30-40% i believe). I plan to investigate further later today

    Update#2: I found a report on the net of a different sound but on the same 20sec cycle (a period that many seem to report). This person took their unit apart and measured the voltages and saw that the sound coincided with a 0.5v increase to the battery. Possibly a battery check cycle? Maybe this cycle doesnt begin until the unit goes under a certain load level? Anyone from APC willing to comment?

    NB: If this gets too complicated I will start a new thread :)

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