Measurement and analysis of partial discharge under high voltage continuous impulses for inverter-fed insulation

Partial discharge (PD) is one of the key factors in insulation failure of inverter-fed traction motor. Due to the high steepness of impulse with broad frequency range, PD under continuous impulses is not easy to be detected by a conventional PD detection system. Impulse current sensor (ICS) has been applied to develop a new PD detection system and the wavelet packet method is used to extract the PD signals. Moreover, the coil of traction motor is used as the test sample. The statistics of test results of PD signals show that PD signals can be successfully identified by the new PD detection system. Finally, issues about the influence of voltage and frequency of square wave pulses on discharge number, maximum discharge and mean amplitude of PD signals are discussed.