Abstract:

In order to understand the post-arc breakdown mechanism of the aviation variable frequency vacuum arc,the experimental and simulation research is carried out.The results show that there are a large number of metal droplets in the vacuum chamber during the post-arc breakdown process for the intermediate frequency vacuum arc.The droplets are moving sources of metal vapor and the life of the metal droplet is 1.6~2.8 ms.During this period,especially the first 100 μs of evaporation,the metal vapor will affect the recovery of the post-arc dielectric.The factors which determine the life of the metal droplet are the droplet radius,jet movement speed and the size of the vacuum chamber.The distribution of the vapor decreases gradually from the center of the droplet.More than 80% of the vapor is distributed within a radius of 10 times.The post-arc metal vapor reduces the recovery strength of the dielectric.When the recovery voltage applied to contact is greater than the critical value,post-arc breakdown will occur.

Key words: vacuum arc, aviation variable frequency power supply system, metal droplet, evaporation