Study on Switching Characteristics and Associated Degradation Mechanism of Contact Material Under Capacitive Load

Electrical lifetime and relative dynamic welding failure mechanisms of an electromechanical relay for a capacitive load are interesting topics in the area of switching devices and contact materials. In this paper, a silver tin oxide contact material has been tested with a capacitive load by using our designed novel model switch. The typical waveforms of contact current and contact voltage at making and breaking are presented. Furthermore, the variations in bounce energy, static contact force, dynamic contact force, arc energy, and contact resistance as a function of operation cycles are plotted and analyzed explicitly. In particular, the intermittent long-duration arcing phenomena during breaking are observed and explained with the variations in local contact asperities. Based on the collected sensitive parameters, an associated physical degradation mechanism of contact materials under the capacitive load is proposed.