Simulation of Electric Arcing in HVDC Relays During a Short Circuit Situation

Electric arcing in high voltage direct current (HVDC) relays is an undesirable phenomenon that many manufacturers seek to fully understand and control. In short circuit situations, the rapid increase of the current causes the arcs to excessively heat, melt, boil, and vaporize the contact spots of the relays. This situation may end in explosion of the relays. In this work, the arcing process of such a short circuit situation is simulated based on time dependent current and voltage measurements at the relay [3]. To analyse the electric arcs in detail, and estimate the resulting vaporization from the increasing current, a multiphysics model which couples current flow, fluid flow, and heat transfer, based on balance equations, is established in COMSOL. The simulation results will show the electric arc formation and time dependent arc evolution. It is expected that; the temperatures of the arcs are high enough to melt, boil, and vaporize the contact materials, which has to be quantified to understand the pressure increase within the relay chamber.