Calculation of the Magnetic Noise of Polyphase Induction Motors

The origin of the magnetic driving forces which are responsible for magnetic noise and a method of calculating the mechanical response of the motor structure are reviewed in this paper. A general method is developed to calculate the sound pressure levels of magnetic noise at a specified point near the motor. The paper gives numerical results of calculations, and the corresponding measured sound pressure levels of the magnetic noise for a particular experimental 4‐pole, 30‐hp, polyphase induction motor under five different operating conditions; calculations agree with measurements within 3 db.