Simulation of Arc Dwelling Behavior During Bridge-Type Contacts Opening Process for High-Power Relay

The importance of high-power relays used to interrupt dc current has been significantly growing recently. In their arc chambers filled with nitrogen or its mixtures, bridge-type contacts with permanent magnets are major measures widely used for arc extinguish. Arc dwelling for a short duration after arc ignition, until its voltage increases rapidly, plays a crucial role in contact erosion. In this paper, arc dwelling time in a nitrogen environment during the entire bridge-type contacts interruption process of a resistive dc circuit is studied both experimentally and numerically. A multiphysics model coupled with the fluid flow, the temperature, the current density, as well as the E- and M-fields was built based on the magnetohydrodynamics theory for the arc chamber. The model was solved in COMSOL. The external resistive electric circuit was connected to the model, and the electric field in the arc was solved by adopting a floating potential. The detailed arc dwelling process is presented and preliminarily discussed according to the calculated temperature and current density distribution sequences. The calculated arc voltage shows good agreement with experimental results. Furthermore, the influence mechanism of breaking velocity on arc dwelling is analyzed by arc voltage. In this sense, the arc dwelling time could be shortened by increasing the breaking velocity within the reasonable extent.