Study on dynamic voltage distribution characteristics of modular triple-break vacuum circuit breaker

In order to get the dynamic voltage distribution characteristics of U-shaped triple-break vacuum circuit breaker based on 40.5kV fiber-controlled vacuum interrupter modules and give references for choosing suitable dynamic voltage-sharing measures, synthetic breaking tests with low voltage and small current were firstly carried out. The transient recovery voltage(TRV) of the three breaks were measured and the results indicate that, the dynamic voltage distribution characteristics after small current interruptions are close to those of static state, the peak transient recovery voltage distribution of the break at the high voltage terminal is more than 60% and 1000pF grading capacitors can satisfy the voltage sharing requirement of breaking small current. Based on the “Continuous Transition Model”, a transient equivalent model of the triple-break vacuum circuit breaker was built by PSCAD/EMTDC and the TRV distribution characteristics and main influence factors after high current interruptions were analyzed. The simulation results indicate that the dissipative processes of residual charges have big impacts on the dynamic voltage distribution, and the synchronism among breaks should be pay attention to in the large current interruption tests followed.