Model of a rotating vacuum are by the coupling of a simple are model with a commercial 3D FEM

We present a model of a rotating arc by coupling a finite element method and an arc model. A FEM software, commercialised under the name Flux3D, is used to calculate magnetic field between electrodes taking into account the real current distribution in the contacts and in the arc; moreover, induced currents and ferromagnetic effects can be taken into account. A phenomenological are 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 are 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. The presented method seems to be a promising tool to describe the behaviour of rotating arcs in vacuum circuit breakers.