Low Pressure and High Temperature Partial Discharge Mitigation Using Electrets

High electric fields induce partial discharges (PD), which accelerate the degradation of electrical insulators and compromise system reliability. Mitigating PD is possible by neutralizing these fields with electrets, which generate their own electric fields independently. Our previous studies have examined the effectiveness of electrets in reducing PD under recurrent, steep voltage pulses at elevated temperatures. In low-pressure and high-temperature environments, this study demonstrates that Parylene HT thin film electrets effectively mitigate PD. PD measurements were conducted at pressures as low as 20 kPa, temperatures up to 260° C, and under steep square voltage pulses with slew rates reaching <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$68.75 ~\mathrm{V} / \text{ns}$</tex>. The results indicate that Parylene thin film electrets enhance insulation performance by reducing PD magnitude and increasing partial discharge inception voltage (PDIV) under extreme electrical and thermal conditions at low pressures.