Simulation Study on the Post Arc Energy Characteristics of Double Break Vacuum Circuit Breaker

Vacuum circuit breakers (VCBs) have been widely used in medium and low voltage distribution system due to their superior arc extinguishing ability and environmental protection characteristics. However, in the application to higher voltage grade, the long gap vacuum arc has a long arcing time and the residual energy of post-arc is large, which is easy to cause restrike and lead to breaking failure. VCB with double breaks can, not only, greatly improves the ability to tolerate TRV, but also has characteristics in arc energy control. A long gap arc is divided into short gap arcs, which can reduce the residual energy density of post-arc, and is favorable to the recovery of vacuum dielectric, and improve the breaking success rate of the circuit breaker. In order to study the influence of arc energy control on the breaking performance of the switch, and to analyze the distribution characteristics of the residual energy between the double breaks, PIC-MCC method is used to simulate the energy distribution during the development of the post-arc sheath. The arc gap distance of single break VCB is set, and the basic data of residual energy density of single break/long vacuum gap is obtained. The single break long gap is divided into two short gaps in series, in condition of the other initial data remains unchanged. Particle simulation is carried out under different TRV parameters to analyze and compare the difference of particle energy between single break and double breaks, and to explore the energy distribution characteristics of double breaks under different TRV rate and different TRV distribution. The difference of energy density under different simulation conditions is obtained through simulation, which verifies the significance of using double breaks to disperse the residual energy of arc, and explores the test conditions for optimal energy distribution between double breaks. The research shows that the double break is beneficial to improve the breaking capacity and service life of VCBs under high voltage and high current conditions.