Research on Arc Erosion of Bridge‐Type Contacts in DC Relays Under Closing‐Breaking Actions

Direct current (DC) relays play a critical role in diverse applications, with bridge‐type contacts being widely employed in modern designs. Current research on contact arc erosion predominantly focuses on single‐break‐point interruption models, which inadequately represent the arc behavior of bridge‐type contacts. To address this gap, this paper establishes a bridge‐type contact arc model for both closing and breaking actions, alongside a moving contact erosion model. These models investigate the complex erosion effects induced by arcs during contact operations under varying voltages and currents, incorporating magnetic blowout effects. Correlation and error analyzes were conducted between the peak‐to‐valley height difference ( R t ) of the molten pool generated by simulated arc erosion on the moving contact surface and the experimental R t parameter. The results showed correlation coefficients and errors of 0.943 and 5.48% for the left side, and 0.995 and 3.78% for the right side of the moving contact, respectively, validating the simulation model's effectiveness. Building on this validation, a contact failure prediction method was developed. This method demonstrates that when the R t value obtained from contact surface erosion under varying conditions exceeds the threshold R tmax = 364.991 μm, the contact exhibits a 92% probability of failure. The simulation model accurately predicts contact failure across different voltage and current scenarios, providing a practical solution for determining contact voltage and current withstand capabilities during the design phase.