limit vibration of transformer

Depending upon kva size the audible sound levels should be between 45db and 60db when measured. There are 2 things you can try:

1) With power turned off to the transformer try tighting up all nuts and bolts in the transformers core and enclosure. A laminated steel core transformer noise level will increase as it gets older. The nuts and bolts inside will work themselves loose.

2) Go back to the transformer manufacture and ask them for Dampening tape you can put this inside the transformers enclosure and it will reduce enclosure vibration.

NEMA Standard TR1 defines noise levels for applicable transformers used by the power industry. This standard includes tables of sound levels as test points, but significant study of the standard will be necessary to apply these values due to the impact of measurement distances. The following table is being provided as "typical" of the kinds of limits defined in this standard.

The NEMA TR1 stanard is available for FREE on the NEMA web site at:

http://www.nema.org/stds/tr1.cfm#download