The recovery speed of the post-arc medium strength directly affects the breaking capacity of the vacuum switch. In this paper, the medium-high frequency current breaking experimental platform was established. The breaking experiments were carried out. The waveforms of post-arc current and voltage were measured. The post-arc equivalent resistance was calculated. The movement of plasma in post-arc process was analyzed. Combined with the experimental results and the emission mechanism, the concept of ‘post-arc plasma depletion zone’ was proposed. The effects of plasma movement and plasma depletion zone on the post-arc equivalent and the value of di/dt were also analyzed.

Vacuum arc; Post-arc process; Plasma; Equivalent resistance