Mitigating Space Charge Injection and Accumulation Using Electrets in Low Pressures

In medium voltage direct current (MVDC) systems, charge carriers progressively penetrate solid insulators, accumulate space charge, and compromise the dielectric strength. The space charge accumulation amplifies electric fields, diminishing the electrical thickness of solid dielectric materials. A few years ago, we introduced an electric field neutralization method utilizing electret thin films to mitigate partial discharge (PD) and space charge. Continuing of our research, this investigation empirically validates the efficacy of integrating electrets to mitigate space charge injection and accumulation when exposed to square voltage pulses in low pressures representing high altitude operation. In various pressures, a square voltage of 5 kV was applied to polyvinylidene fluoride (PVDF) on top of silicone rubber for 30 minutes to induce space charge injection and accumulation in the bulk of dielectric materials. Results from experiments conducted on both non-electret and electret test coupons show that electrets effectively inhibit the injection and accumulation of space charge within the dielectric material. A comparative examination of these experimental findings underscores the capacity of electrets to mitigate space charge injection and accumulation when subjected to square voltage stresses under low pressures.