Analysis of electric repulsion on contacts of different molded case circuit breakers

The electric repulsion between the movable contact and static contact of molded case circuit breakers (MCCBs) will directly affect the breaking speed of the movable contact, which in turn affects its breaking capacity. In order to improve the breaking speed of the movable contact and enhance the breaking capacity of the MCCBs, different MCCBs are proposed in this paper. The distribution characteristics of the electric repulsion between contacts corresponding to different MCCBs are obtained by simulation. The results show that the current density and magnetic flux density at the movable contact and static contact are small under different MCCBs. The closer to the contact-point, the greater the current density and magnetic flux density. When the current is 625 A, the electric repulsion and repulsive torque of the single contact-point contact in the series structure are 131.19% and 448.97% higher than the single contact-point contact in the parallel structure, respectively. Under the same current, the single contact-point contact in the series structure has the largest electric repulsion and repulsive torque, and the movable contact has the fastest movement speed and higher breaking capacity. This study can provide a reference for improving the breaking characteristics of MCCBs.