3-D finite element analysis of magnetic blowout forces acting on the arc in molded case circuit breakers

It is necessary, for the optimum design of molded case circuit breakers, to analyze magnetic blowout forces acting on the arc in the contact systems when the circuit breakers interrupt fault currents. In this paper, the forces generated by the arc current and the flux density are obtained by using 3-D finite element analysis, taking into account the current distribution in the current paths and variations in arc diameter. It is shown that this 3-D analysis approach is capable of evaluating new designs of contact systems in molded case circuit breakers.