SUA1000 and SUA1500 buzzing/humming every 45 seconds

[BillP]

Hi,

I have two Smart-UPS 1000VA and 1500VA that are buzzing / humming every 45 seconds, precisely. And at the same time. They do the same sound like when the UPS are on battery. It's not the fan sound, it's like the humming sound you can hear near a city power plant. It's a very low, deep, "bassy" humm for about 3 seconds.I can hear it from 3 rooms away.

I don't recall them doing this. It's like if they "trickle" charge at the same time..

Any ideas how to keep them more quiet ?

[BillP]

Hi,

I have two Smart-UPS 1000VA and 1500VA that are buzzing / humming every 45 seconds, precisely. And at the same time. They do the same sound like when the UPS are on battery. It's not the fan sound, it's like the humming sound you can hear near a city power plant. It's a very low, deep, "bassy" humm for about 3 seconds.I can hear it from 3 rooms away.

I don't recall them doing this. It's like if they "trickle" charge at the same time..

Any ideas how to keep them more quiet ?

[Anonymous user · Accepted solution]

HI, the fact that they are doing this exactly at the same time could be related to some minor fluctuations on the incoming power that are passing thru the transformers in these units (the likely source of your hummm), combined with the possibility if your batteries are getting old the inverter/charger is working a little harder than it might have been in the past to keep them "trickle" charged. Are these ups stacked directly on top of one another in a rack , or parked side by side ?