For the optimization design of electr ic apparatus

it is necessary and important to calculate the electro-dynamic repuls ion force acting on the movable contact.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.It demonstrates that the number and the d istribution of contact bridges

together with the shape of contact have remarkabl e effect on the repulsion force.Furthermore

the proposed method is effective to calculate the repulsion force.