Interruption and Droplets Emission in Intermediate-frequency Vacuum Arc of Aviation Power Supply System

In order to research the interruption process of vacuum circuit breaker in aviation intermediate-frequency (360~800Hz) power supply system, vacuum arc experiments were carried out in interrupter with the diameter being 41mm and with the contact material being CuCr50 alloy. The relationships between arc voltage and frequency and current, limit breaking capacity and frequency were obtained by fitting the breaking process. The phenomenon of post-arc droplet emission was analyzed and the force and trajectory of droplets were calculated. It can be indicated as follows: with the increase of frequency and current, both the peak value and the rise rate of the intermediate-frequency vacuum arc voltage increase, and the interruption ability decreases. However, the erosion of contacts is weaker for a shorter arc time, comparing to the same power frequency current. When the vacuum arc reignites, droplets are emitted from the contacts with the velocity of 10~20m/s. The drive force is the pressure from the arc area to contact edge, with the gradient of 7.9×104 Pa/mm. © 2020 Chin. Soc. for Elec. Eng.