Decrease of noise

[iskar2000]

Please, would you let me know any method of decreasing noise level of power transformer 40MVA ONAN 123kV to 60dB (A)

 

[GreyGoose]

Noise in a power transformer is due primarily due to magnetostriction, the expansion & contraction of core steel under an alternating magnetic flux, which causes vibration in the transformer assembly. This vibration is transmitted to the air via the transformer tank walls, causing that familiar humming noise. Vibration is also transmitted to the ground via the foundation & may aggravate sound levels. This noise may be further increased by resonant vibration of mechanical parts.

Although a transformer may have passed audible sound level tests in the shop, this is no guarantee that it will perform likewise in the field. Noise levels may increase after installation in the field due to: improper installation, room acoustics (if indoors), loosening of parts during shipment, etc.

Although you will never eliminate the noise (due to magnetostriction), sound levels may be reduced by one or more of the following methods:
1. use of sound absorbing materials on the walls to minimize the formation of standing waves
2. use of sound absorbing materials to form a barrier between transformer housings
3. shock mounting of components susceptible to vibration
4. shock mounting of entire transformer to foundation
5. installation of audio-dampening system
6. inspection of entire transformer assembly to tighten, replace, or eliminate loose connections/parts

hope this helps...also do a search through some old "AIEE Transactions on Power Apparatus and Systems" for articles on tranformer noise & noise mitigation.

 

[busbar]

Small aside: I've been told that acoustic noise from power transformers increases proportional to the square of the applied voltage. {Sorry—no reference here.} Had problems with noise from overvoltage that could not be cured with increasing NLTC tap setting to the full 5%. 115kV winding; 121kV labeled maximum rating; bus voltage was found to be consistently high; periodically reaching 129kV. [So much for tactful or delicate negotiations…]

 

[stevenal]

I found that tightening the nuts holding a nameplate on made big difference.

 

[ausphil]

As an aside, this reminds me of a great interview question for power engineering positions:

Q. Why do transformers hum?
A. Because they don't know the words.

Can give a good insight as to the personal qualities as well as the engineering ability of the applicant.

 

[electricpete]

I can imagine springing that punchline on a candidate after he's just spent 5 minutes discussing magnetostrictive effect etc. Might it also shed light on the personal qualities of the interviewer?

 

[busbar]

A few noise comments at:

http://www.abb.com/global/abbzh/abb...1C616&e=us&c=8C940A880DB97A67C125688D00611B7E

{Wicked link but seems to work OK.}

 

[robertb]

1.Please review noise control methods by Walker lectronic Silencing, INC.
2.Consider adjustment of transformer taps.

 

[jbartos]

Suggestion: Some transformers become noisier when the power quality worsens. This would mean to investigate the voltage and current waveforms at your transformer.

 

[iskar2000]

Thank to all for your answer to now

I woul like to make more precise I speak about design of new transformer (not about exist)with requiremens about sond level no more than 60dB

 

[a2002]

It is not very difficult to drop your ONAN transformer noise under 60dB.