Partial Discharge Characteristics of Electrical Aircraft Machine Winding after Thermal Aging

Electric machines for civil aircraft must have high reliability. However, the harsh operating environment will challenge the machines' insulation system. For electric machines in aircraft, thermal aging is the main reason for insulation deterioration and result in the failure of the electrical machine. Partial discharge (PD) is an essential indicator in evaluating the insulation damage. This paper aims to clarify the PD characteristics of the machine winding before and after thermal aging for aircrafts. It firstly established a thermal aging platform and used a PD measurement circuit to study the behavior of the PD inception voltage (PDIV), phase-resolved PD (PRPD), and PD magnitude before and after thermal aging. The insulation capacitance (IC) of machine windings with different aging stages is also tested and compared with PD characteristics. Results show that thermal aging will decrease the PDIV of winding insulation and PD magnitude increases exponentially after thermal aging.