直流电压下金属微粒对绝缘材料真空沿面耐电性能的影响

Metal particle has been considered to be an important reason leading to surface flashover along insulators. For the safe operation of electrical equipment, it is necessary to study the influence of metal particle on surface flashover characteristics of insulating material in vacuum. Consequently, we studied effects of metal particle on flashover characteristics and surface charging distribution under DC voltage. The results reveal that flashover voltage is significantly reduced when metal particle attaches on insulator surface; the larger the particle size is, the lower the flashover voltage will be, e.g., the withstanding voltage is reduced by 25% for a 2-mm metal particle. When changing the attached position of particles, e.g., near cathode, near anode and in the middle of cathode-anode surface, the flashover voltage is the highest for the first case and lowest for the last case aforementioned. Analyses reveal that metal particle distorts the electric field distribution, then affects the field emission and the secondary electron emission (SEE) process. And the distortion of electric field is associated with the particle size and attached position. So the flashover voltage decreases when increasing the particle size, and also changes with the particle attached position.