3D-simulation of arc motion between arc runners including the influence of ferromagnetic material

The behavior of the moving electric arc in low-voltage switching devices is determined by the complex interactions of magnetic forces, current flow, gas flow, heat conduction, and radiation. In this paper, three-dimensional simulations of arc motion between parallel arc runners are presented, which consider all these interactions. These simulations are carried out with a CFD (computational fluid dynamics) finite volume code. Based on earlier simulations (Karetta and Lindmayer, 1998; Karetta, 1998), the magnetic field, expressed as a vector potential formulation, is now treated by the same type of general transport equations as the other processes, which allows direct implementation into the CFD package used. This enables inclusion of the effects of ferromagnetic materials in the arc chamber, such as ferromagnetic flux concentrators or steel splitter plates. Typical simulation examples are presented for different design details.