Interrupting capability of vacuum interrupter by various parameter

Vacuum interrupter (VI) has been commercially available in medium voltage switching equipment. Recently, the development of the VIs is focused to reduce the size. Thus, it is necessary to a smaller size contact. In this paper, we investigated the interruption behavior in the real VI with two different contact size of the transverse magnetic field (TMF) type which is widely used for interrupting the arc current in vacuum. Additionally, we investigated the interrupting capability according to the change of opening speed by using contact with the lower interrupting performance obtained from earlier tests. In our experiment, CuCr25 contact was applied, Weil-Dobke voltage superposition circuit was used for a short circuit current test. Through the correlation between the contact size and opening speed, we could design a smaller VI, and it was applied to 17.5kV 25kA vacuum circuit breaker (VCB).