Calculations of electric and magnetic fields and joule heating in a vacuum interrupter

High-current circuit breakers based on vacuum interrupter (VI) represent an alternative type of switching equipment suitable for operation under severe climatic conditions. Such devices can offer a number of other technological or environmental benefits compared to the currently used ones. Bringing the performance of the VI-based circuit breakers to the level of ~3 kA nominal currents, ~40 kA rate breaking currents and ~100...200 kV operational voltages requires improved physical models and advanced computational capabilities for the description of their operation. According to contemporary concepts, to ensure working efficiency of a device, in addition to addressing the issues of electrical strength, it is important to account for the system of magnetic field generation between electrodes, which influences the flow of current in the electrode gap and formation of a uniform diffusive discharge. In this paper we present the results of preliminary calculations of electric and magnetic fields for the case of a simplified VI design accounting for the shape of magnetic field generation electrodes and conducting material between them. We explore the effects of magnetic materials used in the chamber design and calculate the force acting on the electrodes and electrode heating by the flowing current. The simulation results can be used to find critical parameters and design regions, and represent the first stage in the modeling of VI operation, which at the next stage should take into account plasma generation at the electrodes.