High frequency current interruption ability in vacuum circuit beakers leads to multiple reignitions of the vacuum gap and causes very high and steep over-voltages (voltage escalation). This phenomenon is strongly depended on parameters of electrical system, where the interrupter is located. In this paper, the over-voltages produced by re-ignition of the vacuum circuit breakers used as generator circuit breaker for generators with rated powers in the range of 50 to 300 MVA have been taken into consideration. The simulation results indicate that the protective capacitors in the system side and the percentage of load shedding are important factors in voltage escalation and consequent reignition which occur in vacuum interrupters. This protective capacitor reduces Reverse Recovery Voltage (RRV) and frequency of transient signals, although the reignition current itself increases.
S. Hasanzadeh, K. Niayesh and H. Mohseni
High Voltage Laboratory
School of Electrical and computer engineering
University of Tehran