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 fiel d between the contacts in vacuum chambers at the instant when the are current becomes zero. The residual magnetic field is generated by the eddy currents flowing in the electrodes. In this paper, the residual m agnetic field is obtained by using a 3-D finite element analysis takin g into account eddy currents, It is shown that the eddy currents are g reatly influenced by the configuration of the electrodes e.g. the numb er of slits in the contacts.