Post arc current of vacuum interrupter after large current interruption

Postarc current characteristics of a vacuum interrupter have been examined under a condition of high-current interruption. A measurement technique was developed in which a shunt for measuring postarc current was set in a synthetic test circuit voltage source. Postarc current was measured after a 20-57 kA current interruption. The magnitude was greatly influenced by the rate of current decline. Residual resistance between electrodes was calculated from the measured values of recovery voltage and postarc current. The recovery of residual resistance was very rapid immediately after current zero and become slow later