It is very important and necessary to calculate the electro-dynamic repulsion force acting on the movable conductor for the optimization design of air circuit breaker (ACB).

With 3-D finite element analysis, the current between make contacts, magnetic field around make contacts and electro-dynamic repulsion force acting on the movable contact are analyzed by the finite element simulation software ANSYS.

Paper present a project of application of on-line contact compensation in vacuum circuit breaker with the theory of electrodynamic repulsion force.

The model is confirmed by experiments on the mechanical performance of the tested circuit breakers, which also paves the way to the further study on the impact of the electrodynamic repulsion force on the circuit breaker and the optimization of the mechanical design.

With 3-D finite element nonlinear analysis, according to the equations among current-magnetic field-repulsion force and taking into account the ferromagnet, two methods for calculating the Holm force due to current constriction between contacts, Holm formula and introducing cylinder bridge model, are compared.

With 3-D finite element nonlinear analysis, according to the equations among current-magnetic field-repulsion force and taking into account the ferromagnet, repulsion force acting on the movable contact can be calculated.

With3-D finite element analysis,accordin g to the equations among current-magnetic field-repulsion force,the contact bri dge model is introduced to simulate the current distribution between contacts,so the repulsion force can be calculated.

In this paper, the new configuration theory of contactor is devised to resist hot agglutinative force, cold agglutinative force and electric repulsion to increase working reliablility through analytical study on runing away of contactor.