The phenomenon of surface discharge in these three cases is quite different. During live working, the third case is common. The principle of discharge phenomenon in this case is described in detail below.

 

 

 

由于这种情况下电极本身的形状和布置已经使电场很不均匀，介质表面积聚电荷使电压重新分布所造成的电场畸变不会显著降低沿面放电电压。另外，电场垂直分量较小，沿表面也没有较大的电容电流流过，放电过程中不会出现热电离现象，故没有明显的滑闪放电。垂直于放电发展方向的介质厚度对放电电压实际上没有影响。同前两种情况相比，闪络电压数值更接近于空气击穿电压。在这种情况下，需要提高沿面放电电压的手段，一般是改进电极形状，以改善电极附近的电场，从而达到提高闪络电压的目的。

 

In this case, the shape and arrangement of the electrode itself have made the electric field very uneven, and the electric field distortion caused by the redistribution of the voltage caused by the accumulation of the surface charge of the dielectric will not significantly reduce the discharge voltage along the surface. In addition, the vertical component of the electric field is small, and there is no large capacitance current flowing along the surface. During the discharge process, there is no thermoelectric separation phenomenon, so there is no obvious flashover discharge. The dielectric thickness perpendicular to the development direction of discharge has no effect on the discharge voltage. Compared with the former two cases, the flashover voltage is closer to the air breakdown voltage. In this case, it is necessary to improve the discharge voltage along the surface by improving the electrode shape to improve the electric field near the electrode, so as to improve the flashover voltage