A transformer converts an alternating current to an alternating magnetic flux and then back into an alternating current. The alternating magnetic flux can result in mechanical motion in the iron core of the transformer, which can cause humming. We refer to this as magnetostriction.
In general, the higher the capacity of the transformer, the louder the hum. The humming is often transferred via the fixings to the floor where the transformer is located, and so to the rest of the building.
Our vibration dampers, Silent Blocks, can be installed to prevent this. These rubber dampers absorb much of the vibration coming from the transformer. They don't prevent the transformer itself humming, but they do prevent the vibrations going into the floor.
Whether transformer hum is found to be a nuisance depends on a number of factors:
1) The transformer itself
A larger transformer will hum louder. Exceptions to this are found in our EC/IRC, ECT/IRC and PVT series. These types barely generate any noise as the magnetic induction is very low.
2) The substrate
It's fairly obvious that a timber structure will result in more noise than a poured concrete floor.
3) The environment
A transformer in a plant room in the basement will cause less disturbance than one located in a cabinet in an office space.
We can supply a range of vibrations, each capable of handling a certain maximum weight. A transformer of up to 80kg can be damped with four Silent Block 20s (20kg loadbearing capacity each).