The evaluation of prominent parameters on post-arc current characteristics in vacuum interrupters

Summary form only given. The appropriate performance of vacuum interrupters is mainly divided in two phases; current interruption phase which supposed to be fulfilled before current zero and post-arc or voltage recovery phase after current zero. The particles in residual plasma after current zero are accelerated by transient recovery voltage (TRV). Therefore a current in the order of some ampere and duration of some microseconds commences after current zero which is called post-arc current. The characteristics of the post-arc phase are in close relation with initial ion density and its distribution between cathode and anode. These two parameters are strongly dependent on the arcing time and extinguished fault current amplitude and the intensity of the externally applied axial magnetic field in the interruption chamber. In this paper, the propagation of ions after current zero is simulated and the effect of external magnetic field and its strength on post-arc phase is investigated. Furthermore, some modifications have been applied in the shield of vacuum interrupter to improve the ability of interrupter in dielectric strength recovery of vacuum.