In recent years, the demand for a three-phase squirrel-cage induction motor (IM) that generates less noise has increased considerably. Electromagnetic noise is caused by electromagnetic vibration, which is generated by the interaction between the magnetic flux density waves in the air gap. Hence, we study the cause of electromagnetic vibration and noise in order to aid the design of a lower noise IM. However, the radial distributions of electromagnetic vibration and noise are asymmetric because the construction of an IM is asymmetric, for example, existence of terminal box and legs for fixed on a device. In this study, the radial distributions of the electromagnetic vibration and noise in an M which are measured using two pickups and two microphones driven by a sinusoidal waveform generator, are examined experimentally.
