In order to investigate the influence of the overcharge on the vacuum direct current（DC） forced current-zero interruption

based on the permanent-repulsion high speed hybrid actuator and forced current-zero interruption method

a series of DC interrupting experiments were carried out in a synthetic test circuit. With the established devices for the measurement of post arc current and dielectric recovery strength

chopping current

post arc current and dielectric recovery strength were investigated under the condition of overcharge

and the relationships among the three parameters and overcharge were obtained. The results indicate that the chopping current

post arc current and dielectric recovery strength all increase with the overcharge voltage. The influence of the commutation frequency on the chopping current and post arc current is dominant

which is superior to the influence of the overcharge voltage. In addition

the interruption fails at the first current zero

when the overcharge voltage exceeds a certain value. Under the conditions in this paper

the overcharge voltage of the commutation capacitor should be controlled within four times of the critical commutation capacitor voltage that can enable the interruption successfully.