纳秒脉冲下同轴内电极直径改变时闪络特性分析

Relationship between flashover and inner electrode diameter under nanosecond pulsed coaxial electric field

在纳秒脉冲同轴电场下,尼龙1010和有机玻璃的闪络电压都随着内电极直径非线性增长,趋于饱和,且内电极直径越大,两者的闪络电压越接近。纳秒脉冲下沿面闪络特性与固体-液体-电极三结合点处的场强及沿面电位分布梯度紧密相关,内电极直径越大,三结合点处场强越低且沿面电位分布越均匀,引起沿面闪络电压越高。对于纳秒脉冲下的同轴电极,当内外电极半径差远大于内电极直径时,内电极直径变化对闪络电压的影响被弱化。

Under nanosecond pulsed coaxial electric field, surface flashover voltages for both nylon 1010 and polymethyl methacrylate （PMMA） in transformer oil increased with the inner electrode diameter and then were saturated, and the larger is the inner electrode, the closer is the flashover voltage induced between them. Surface flashover properties were closely related to the electric field at the triple junction of solid-liquid-electrode and the field gradient along the interfaces between solid and liquid, so that the larger is the inner electrode diameter, the higher flashover voltage is owed to resultant depressed field strength at triple junction and the averaged potential distribution along interfaces. If inner electrode diameter value was far largeer than outer electrode diameter＇ s, the influence of inner electrode diameter on flashover voltage would be weakened for nanosecond pulsed coaxial electrodes.