Multiple Re-Ignitions in Small Inductive Current interruption by Vacuum Circuit Breakers

It is well known that over-voltage induced by re-ignition is dangerous for the safety and stable operation of power system. The objective of this paper is to determine the effect of load parameters on multiple re-ignitions due to dielectric breakdown in vacuum circuit breakers after interruption of small inductive currents at short gaps. A sheath development model was used to analyze the dielectric breakdown in vacuum. Therefore ion concentration, ion speed, development of electric field and potential time and space were calculated in various TRV parameters. The results showed that increasing capacitance value extend the sheath development time and decrease maximum field strength, which decrease the risk of re-ignition. Otherwise, increasing the load equivalent resistance don't directly influence micro-dielectric recovery process of vacuum gaps, but it decreases the load current and then it regulates the sheath development time and maximum field strength, which reduce the risk of re-ignition. Load equivalent parameters regulate the amplitude and frequency of TRV, thus dielectric recovery process of vacuum gaps is influenced, which has a direct impact on re-ignition.