Influences of humidity and temperature on oil contamination discharge of HV motor stator windings

The leaking oil, as one typical contamination in stator windings of high voltage motor, will corrode stator winding and be dissolved in the grounding insulation layer. The oil contamination could lead to the stratification of insulation, the reduction of dielectric strength and the occurrence of partial discharge. In order to investigate the influence rules of humidity and temperature on oil contamination discharge of stator windings, two discharge winding models with oil contamination were made. At twice the rated line-to-earth voltage of 6 kV, two windings were aged for 240 hours under different relative humidity and temperatures, respectively. The phase resolved partial discharge (PRPD) patterns were monitored and analyzed during the short aging period. The experiment results confirm that temperature and ambient humidity have a significant impact on the oil contamination discharge of winding. The PD intensity of oil contamination increases with the rise of temperature. The creeping phenomenon will take place at the higher relative humidity. In addition, it will provide a judging basis for the on-line monitoring and fault diagnosis of the 10 kV three-phase asynchronous motors.