脉冲陡度对快脉冲下真空沿面闪络特性的影响

Influence of Pulse Steepness on Vacuum Surface Flashover Characteristic under Steep Pulse

为了研究高压快脉冲下绝缘材料的真空沿面闪络机理,从脉冲陡度角度出发,在真空度5 mPa水平下,通过5种脉冲源形式,13种输出电压,测量了环氧试样在不同脉冲陡度下的真空闪络电压。通过数据的分段拟合,结合闪络时延特性以及在高脉冲陡度下洛伦兹力对电子运动的影响,讨论了脉冲陡度对闪络电压的作用机制。分析表明,脉冲陡度很低时(<1.5 kV/ns),闪络电压主要受闪络形成的统计时延的影响;脉冲陡度较高时(几kV/ns^10 kV/ns),闪络的形成时延也成为影响闪络电压的重要因素;脉冲陡度很高时(>十几kV/ns),闪络电压受闪络时延和洛伦兹力共同影响。

To research the vacuum surface flashover mechanism of insulation material under steep high pulsed voltage, considering the steepness of the pulsed voltage, remaining the vacuum on the level of 5 mPa, using 5 kinds of pulse generators （4 ns/25 ns） referring to the rise time and the half-height width time of the pulse）, （6- 17） ns/300 ns, 20 ns/530 ns, 50 ns/600 ns, 100ns/550 ns） and 13 kinds of output waveforms, we measured the vacuum flash over voltages of epoxy resin under different steepness. Moreover, 3 kinds of equations were applied to fit the data of different voltage steepness stages. Taking into account of the flashover time delay characteristic and the Lorentz force, the effect mechanism of pulse steepness to the flashover voltage was discussed. The conclusion can be drawn that, when the pulse steepness is very low （below 1.5 kV/ns）, the statistical time is the most significant factor affecting the flashover voltage; when the pulse steepness is higher （about some kV/ns to ten kV/ns）, the formation time delay becomes another important factor affecting the flashover voltage; when the pulse steepness is very high （above 10kV/ns）, the Lorentz force affects the flashover voltage a lot too.