Coupling of an electrical arc model with FEM for vacuum interrupter designs

We present a model of a rotating arc by coupling a finite element method (FEM) and an arc model. A FEM is used to calculate magnetic field between electrodes taking into account the real current distribution in the contacts and in the arc; moreover, ferromagnetic effects and induced currents can be taken into account. A phenomenological arc model is used to predict the arc voltage, which depends on the local magnetic field and the arc length. This arc voltage is updated as the arc displaces itself across the contact surface. The information about arc voltage and local circuit equations is sufficient to find the velocity of the moving arc; hence this model seems more effective than models using Lorentz-forces to describe arc movement which need a priori knowledge about viscosity. This presented method seems to be a promising tool to describe the behavior of rotating arcs in vacuum circuit breakers.