Where does the constant humming sound come from in transformers?
Asked by: John Alerton
Most transformers make some audible sound at the frequency of the current they're operating
on, for transformers running on utility power in the US this is 60 Hz. The sound is due
mostly to the wire in the transformer coils and the steel in the transformer core vibrating
at 60 Hz because of the interaction of the magnetic fields of these components. Some of
this sound may also be due to something called magnetostriction in which the steel of the core
actually expands and contracts with the fluctuating magnetic field.
Answered by: James Hess, President, Hess Electric, Inc.
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