300 Kva UPS having noise in transformers

[Mohi.deen]

Dear Engineers

Hope you all doing well

I have question regards 300KVA UPS

300KVA ups have problem with Transformer raises the noise when I’m increasing the DC battery voltage via Debug test mode? We just replaced the DC capacitors and all other modules working in good condition.

What I should do to reduce the noise in Transformer?? UPS NEED TO BE RUN NORMALLY WITHOUT ANY UPNORMAL SOUNDS

Thanks Regards
Mohi

 

[Parchie]

Any idea if it's an electrical noise?

 

[Mohi.deen]

The Noise is exactly from Transformer (in-build) of the UPS

 

[dpc]

Hard to evaluate remotely because ALL transformers make noise. In a 50 Hz system, it will mainly be at 100 Hz and for a 60 Hz system it is at 120 Hz. Google magnetostriction. That said, it's possible the transformer is being overexcited or experiencing some mechanical resonance condition. Or the mounts could be loose. If this is "normal" transformer noise, isolating the transformer from the structure or floor using some type of soft mounting can help. It's a mechanical issue, not electrical. Years ago, ferroresonant transformers were used in these applications and these can be quite noisy. Not very common today, I don't think.

Good luck,

Dave

 

[JASGripen]

Transformers always vibrate and make noise - how to make it less is an installation problem.
Look for loose bolts and even the common error of installing rigid metal conduit to and out of the transformer unit instead of metallic flex.

 

[rcw retired EE]

"Raising DC voltage" means the input rectifier was changing its firing angle and allowing more current flow to the batteries. (Or were the batteries disconnected?) Noise could be from the increased current in the windings or from harmonics in the current waveform or just the natural increased noise as a transformer loads up.

If you can safely get a waveform on a 'scope or meter, see if there is a relation between waveform harmonics and the noise.