BR550GI noise every 5 seconds

[cptbill_apc]

This was originally posted on APC forums on 6/23/2013

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Hello everyone

I purchased an APC BR550GI 2 days ago to use for my pc.

I hooked it up and and my surprise it make a very annoying buzzing noise with a weird repetitive sound every 5 seconds.

It didnt seem normal to me although the sound could be heard from a distance of about 10m. ( there is a video i shoot with the sound here--> Apc br550gi ups buzzing sound - YouTube )

I thought that i better wait for the battery to be fully charged (although the indication of battery was showing that it was fully charged which i found weird).

Now 24 hours later, the volume is decreased but there is still a weird and repetitive sound every 5 second . Here is a video Ups apc - YouTube

The problem appears even with zero load(nothing plugged into the unit) or with my pc pluggin in.

I really cant stand the noise and doesnt seem right to me. ANy clues? Something i can fix myself? Should i return it?

[Battman_apc]

This was originally posted on APC forums on 6/24/2013

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UPS's sometimes produce mechanical buzzing sounds due to the high operating frequencies of their conversion/inverter stages, coupled with the tap-switching transformers which themselves can vibrate. The repetitive 5 seconds buzz could be a combination of two frequencies that are very close to each other causing a mechanical "beating" (difference frequency) when mixed together, or just some aspect of the UPS design that does some internal process in the conversion or charging circuits on a repetitive basis.

[cptbill_apc · Accepted solution]

This was originally posted on APC forums on 7/4/2013

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i understand the buzzing sound that u can hear by going next to the ups, but a buzzing sound that wont let u sleep, watch tv and is more noticable that anything else on a living room and can be heard from 10m??...well, that AINT normal.

Got my replacement unit yesterday from APC and its running quiet. So mine was a faulty unit.