The noise of the transformer is mainly caused by the magnetic induction generated by the core and the winding, and the noise generated by the magnetic field induced longitudinal vibration of the core lamination is the main component of the transformer noise. The amplitude of the vibration is related to the magnetic flux density in the core lamination and the magnetic properties of the core material, but has little to do with the load current.
The reason why the iron core generates noise is mainly that the size of the silicon steel sheet changes slightly under the action of the alternating magnetic field. Since the variation period of magnetostriction is half a cycle of the power supply frequency, the vibration of the transformer body caused by magnetostriction is based on twice the power frequency, so the vibration of the silicon steel sheet is mainly the magnetic material of the ferromagnetic material. Caused by the telescopic properties.
The magnetostriction rate is related to the material of the silicon steel sheet. The larger the magnetostriction rate, the greater the noise. When the magnetic field strength is the same, the silicon steel sheet of good material has a small magnetostriction, so the noise is also small.
The magnetostriction rate is also related to whether the surface of the silicon steel sheet is painted or annealed because the coating has adhesion to the silicon steel sheet to prevent deformation of the silicon steel sheet. A silicon steel sheet annealed at the same magnetic field strength is much smaller than a magnetostrictive sheet of a non-annealed silicon steel sheet because the optimal annealing process is selected to double the magnetostriction.