The capabilities and advantages of vacuum interrupters have been widely recognized on switching and controlling the fault currents in medium voltage level, and there have been doing various research and developments for using vacuum interrupters in transmission and distribution lines due to its environmental friendliness. Axial magnetic field electrodes are widely used in vacuum interrupters because the axial magnetic field can keep vacuum arc in a diffuse arc mode at high current level. It can be created by the design of electrodes itself or by external coils of a vacuum bottle where current flows. The interruption capacity of the vacuum interrupter can be increased by the magnitude of the field since the arc gets a diffused mode when the field between a contact gap is enough sufficiently. In this study, three-dimensional coupled-fields analysis of high-current vacuum arcs with an axial magnetic field which is produced by a cup-type electrode itself was conducted. We used a commercial multiphysics package, ANSYS, for coupling the fields which are connected with electromagnetics and hydrodynamics sequentially. It was found that arc constriction with the magnitude of applied currents could be predicted well with the temperature distribution of a contact gap.
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