Study of impulse stress gradient on stator winding of HV explosion-proof motor

The impulse performances of stator winding insulation system for 10kV ac explosion-proof motor with the type of protection increased safety are studied in this paper. The measurements of impulse voltage waveforms along one stator winding from the phase terminal to neutral had been carried out. The calculation of electric field on the air gap and surface of stator end-winding were calculated. The impulse voltage and its gradient distribution along the stress gradient coating of end-windings were also calculated. The results showed that the impulse voltage may cause a high electric field or gradient localized on the surface of stator end-winding. The characteristic of stress gradient coating suitable for the impulse voltage was optimized and designed also.