bought used apc 3000 rt making buzzing noise normal?

[ak1ca]

Hello all bought used APC 3000 RT and its making buzzing sound at the back. I assume thats from transformator  and its normal ?

[RyanG32]

Normal sounds and audible noise from a UPS include constant humming from fans and magnetic components, buzzing from capacitors and power electronics devices, and occasional clicks from relays and electromechanical devices, among others.  On-battery operation typically results in a louder noise profile; this is completely normal, as more power devices are active in that state. Increased load on the UPS will also result in more audible noise from the UPS. Once again, this is entirely normal. In addition, a UPS will emit beeps or constant tones during power events and faults.  Alarm sounds are described in the user manual and are clearly identifiable as such.  This type of UPS is a double online convertion unit so unless it has green mode enabled it will convert AC to DC and back to AC again to make sure your power stays consistent.

Unless the noise does not go over 55 dBA the unit is normal but please monitor if it is caused by a certain load or if it happens when you have more load than usual or it if happens only when it is on battery.

Based on the video I think the sound is coming from the fans and it still sounds normal to me the audio may be too low though if the fans is too noisy mean that it needs lubrication or cleaning or on some units a firmware update may fix please check firmware release notes before upgrading since the firmware update can cause the unit to stop working entirely if interrupted or if wrong firmware is applied.