Research of Dynamic Optimization for the Cam Design Structure of MCCB

An optimum design method, which is based on the interruption model of molded case circuit breaker (MCCB), is proposed for the cam design structure. First, it constructs a multifield coupled calculation model that enables us to simulate the interruption process of MCCB. The model carries out second development of Automatic Dynamic Analysis of Mechanical Systems (ADAMS) and constructs a set of differential equations describing the coupling of air blast process with complex mechanical movement, electric circuit, magnetic field, and dynamic arc model. With this model, investigations on the cam design structure's lock effect during the interruption process of an actual MCCB are carried out. According to the fact that the movable conductor could not be locked under some interruption currents, an optimum design is made for its cam design structure. Simulation results show that after optimization, the cam design structure can prevent the movable conductor from returning when the short-circuit current is no less than 15 kA, and observably enhance the interruption performance of MCCB.