Research on Switching Capacitor of Vacuum Circuit Breaker

In recent years, vacuum circuit breakers have been widely used in distribution networks and medium-voltage systems, especially in frequent operations. Therefore, vacuum circuit breakers are usually used to switch capacitors in shunt capacitor compensation devices. After a lot of research, it is pointed out that the vacuum circuit breaker has the phenomenon of delayed re-breakdown after arc, which may lead to re-ignition, and then produce high-amplitude re-ignition overvoltage. Especially in the case of multi-phase re-ignition, it seriously threatens the safety of the compensation device and the system, and damages the service life of the capacitor, and may even endanger the insulation performance of the equipment. This paper discusses the basic mechanism and working principle of vacuum circuit breaker, focusing on the analysis of the mechanism and harm of cut-off overvoltage, reburning overvoltage and closing inrush current. The theoretical and simulation analysis of vacuum circuit breaker switching 35 kV capacitor is carried out. In this paper, six groups of 5MW capacitor banks are used, and PSCAD simulation software is used to simulate the inrush current and overvoltage transient process of different capacitor banks ( synchronous input and asynchronous input ).