Fluctuation and change of partial discharge inception voltage under high humidity for rectangular wire motors

This paper aims to clarify the mechanism of fluctuation and change characteristics in the partial discharge inception voltage (PDIV) between motor coils constructed from rectangular wires under high humidity environments. To achieve this, the PDIV at 50Hz after pre-discharge between the coil wires were measured at 90% RH for a motor stator and test pieces, both of which were composed of rectangular wires. Electric field analyses were performed for several contact patterns between the rectangular wires for different values of surface conductivity. As the results, we clarified that the PDIV fluctuation and change in rectangular wire motors under high humidity can be caused by a superposition of the various PDIV characteristics for each contact pattern between the coil wires in the motor.