Numerical and experimental study of the short-time withstand current capability for air circuit breaker

A 3-D transient finite-element method to analyze the short-time withstand current for an air circuit breaker (ACB) is presented. The cylindrical contact bridge is adopted to describe the current constriction between the movable and fixed contacts, and then considering the influence of the eddy current, the resistivity and thermal conductivity variations with the temperature, and the coupled calculation of the corresponding electromagnetic field and thermal field can be performed to evaluate the short-time withstand current capability. To verify the calculation method and results based on the ACB model, relevant experiments are also conducted through measuring the temperature of two points on the contacts with the thermocouple. It demonstrates that the proposed method can be used to optimize the design of ACBs.