Increasing Partial Discharge Inception Voltage at High Temperatures Using Parylene-HT Electrets

Electrets are dielectric materials that generate electric fields independently, without an external voltage source. Our previous studies elucidated the process of designing, fabricating, and employing electrets to counteract locally concentrated high electric fields and mitigate partial discharge (PD) under recurrent, steep voltage pulses. Despite the remarkable performance of the PVDF-based electrets reported in our previous research, the limited temperature range of PVDF remains a significant challenge. To overcome this challenge, this study employs Parylene HT thin film electrets and demonstrates PD mitigation at elevated temperatures. We measured PD under steep square voltage pulses with slew rates as high as 75 V/ns and at temperatures as high as 260°C. The results indicate that Parylene thin film electrets can reduce PD magnitude and increase partial discharge inception voltage (PDIV) in harsh electrical and thermal conditions.