Preliminary study on switching characteristics of silver tin oxide type contacts for capacitive load

Electrical lifetime and relative dynamic welding failure mechanisms of electromechanical relay for capacitive load are hot topics in the area of switching devices and electrical contact materials. In this work, the 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. Further, the variations in contact resistance and contact force as a function of operation cycles are plotted and analyzed explicitly. Particularly, an intermittent long-duration arcing phenomena during breaking is observed and explained with the change of arcing duration and obtained SEM image. Finally, the associated physical degradation mechanism of contact material is proposed.