Numerical analysis of axial magnetic field acting on the arc in vacuum circuit breakers by 3-D finite element method taking into account eddy currents

It is necessary for the optimum design of vacuum circuit breakers with axial magnetic field electrodes to analyze the residual magnetic field between the contacts in vacuum chambers at the instant when the arc current becomes zero. The residual magnetic field is generated by the eddy currents flowing in the electrodes. In this paper, the residual magnetic field is obtained by using a 3-D finite element analysis taking into account eddy currents. It is shown that the eddy currents are greatly influenced by the configuration of the electrodes, for example the number of slits in the contacts.