基于电弧力效应理论对开关型SPD续流的研究

Research on the Postarc Current of Voltage Switching Type SPD Based on Theory of Arc Force Effect

针对开关型SPD续流的问题主要是由于两电极气隙击穿时,击穿电压较低引起。通过电极击穿时电弧力效应理论的分析,得出电弧力主要由电子力、静电力、电磁力、等离子流力等组成。采用8/20us模拟雷电波冲击气体间隙,试验得出冲击电压在17.5k V-20k V以下时,电极所受电弧力与冲击电压呈正相关,冲击电压值在17.5k V-20k V以上时,电极所受电弧力与冲击电压呈负相关,且电弧力始终不小于零,即电弧力对电极的作用主要为向外的排斥力。提出了在开关型SPD设计中,放电电极一个处于固定状态,另一个电极处于可动状态,利用电弧力效应,拉长电极间隙的长度,增加两电极间残压,起到提前灭弧,减小续流的方法,在实际应用中,具有一定的实用价值。

The problem of voltage switching type SPD＇s postarc current is caused by the lower breakdown voltage across the gap of two electrodes. Based on the research of arc force effect when the electrodes start to break down ,it is concluded that the arc force mainly consists of electronic force, electrostatic force, electromagnetic force and plasma flow force. In this research, air gap is impacted by 8/20μs impulse current. Through the experiment,it could draw a conclusion that when the impulse voltage is below 17.5 kV to 20 kV ,the arc force on the electrodes represents a positive correlation with the impulse voltage. When the impulse voltage is above 17.5 kV to 20 kV,the arc force represents a negative correlation with the impulse voltage and the arc force is always not less than zero ,which means the effect on electrodes is a outward repellent force. It is proposed a new method in the design of voltage switching type SPD that one discharge electrode is fixed, the other is movable,which can use the effect of arc force to elongate the length and raise the voltage between two electrodes. In this case, arc would be extinguished in advance and the postarc current would be reduced,which has a certain reference value in the practical application.