When you crossed across a transformer in your locality, you might have listened to the humming noise coming from the transformer. It is quite annoying if the transformer is located in a residential area.
The cause of transformer noise is the magnetostriction. We have written an article on Magnetostriction topic.
As we know that the transformer core is made up of ferromagnetic material. The ferromagnetic material has the property that when it is magnetised, the material length increases and decreases alternately. Hence the transformer core length dimension changes. This phenomenon is called as magnetostriction. Due to this steel laminations changes their dimension alternately, and hence results in transformer core vibration and humming sound is produced. The humming in the transformer is directly proportional to the core flux density. Greater the core flux density, more humming is there. The forces produced by the magnetostriction phenomenon are much higher than the magnetic forces in transformers. Levels specified are 10 to 15 dB lower than the prevailing levels mentioned in the international standards.
How to reduce noise from a transformer?
The noise emission from the transformer can be reduced
- by tightening of the core by the bolts, clamps, etc.
- by using a low value of flux density in the core.
- by installing a sound insulation in the transformer core.