Study on Arc Generated by Opening Electromagnetic Relay Contacts in DC Low-Current Resistive Circuit with Constant Velocity

摘要

An electrical arc is generated by opening the contacts of a relay when the current is above the minimum arc current in a circuit. A magneto-hydrodynamic (MHD) model was employed to simulate this dynamic arcing process. The distributions of arc parameters such as temperature, electrical field and magnetic flux density generated by opening the contacts in a circuit with a 5 A DC low current were obtained. The behaviors of the arc parameters with increasing gap length between the contacts were also simulated. The MHD model was then combined with structured dynamic layering, which is a dynamic meshing technique of computational fluid dynamics (CFD) to calculate the dynamic arcing process, and the arc parameters generated by opening the contacts in the circuit with a 5 A DC low current with a constant velocity were also obtained. It turned out that the computed time-varying contact voltage and arc duration agreed well with the test results. Thus, the validity of the simulation was demonstrated.