Coupling Simulation Study on Dislocation Slip of Self-Elastic Arcing Contact Sets of SF6 Circuit Breaker

High voltage circuit breaker plays a very important role in the safe operation of the power grid. One of the core components, self-elastic contacts made of tungsten-copper alloy, undertakes the task of switching circuits in its operation. The mechanical properties of the contacts are degraded during operation due to defects such as stress relaxation and metal fatigue. So that the contact force between the movable contact and stable contact decreases, which will lead to a serious failure of the circuit breaker. Since the contacts are inside the arc-extinguishing chamber and surrounded by SF6 gas, it is difficult to achieve an accurate measurement of their mechanical properties. Therefore, the relationship between the plastic stress–strain of the contact and the change of the circuit breaker opening and closing must be calculated with the help of simulation technology. MATLAB and ABAQUS are combined to establish a discrete dislocation dynamics finite element coupling simulation program for tungsten-copper alloy self-elastic contacts, to simulate the dislocation evolution, and then to establish the contact plastic stress–strain relationship. The establishment of the model helps to understand the mechanical properties of the contacts during the operation of the circuit breaker, and this method is important for maintaining the safe and stable operation of the circuit breaker.