Simulation Research of Fracture Capacitance of SF6 Circuit Breaker in Separating Brake

SF6 circuit breaker is equivalent to a capacitor between the fracture surfaces after the break port separation during the switching process. At this time, the fracture capacitance-stroke curve may be closely related to the ablation state of the contact, which is a potential life evaluation scheme. Therefore, this paper builds a typical 126kV SF6 circuit breaker arc chamber model, and calculates the capacitance curve of the separating brake. The results show that the capacitance value of the fracture is about 21 pF when the switch is off, and the capacitance value after the switch is stable is about 7 PF. The capacitance curve shows a trend of rapid decline and tends to be stable. The results can provide a basis for the subsequent use of dynamic capacitance curve to evaluate the electrical life of circuit breakers.