The investigation of surface characteristics and contact resistance of DC relay contacts

Examination of the contact morphology, surface composition, and contact resistance of DC relay contacts for two levels of low-current (less than 1 A) arc has shown that a similar contact erosion mechanism and similar contact resistance degradation exist for 0.5- and 0.75-A switching resistor loads. Material transfer is attributed to ion sputtering during arcing, as is the degradation of contact resistance determined at different operating cycles, which appears to be influenced by both the contact morphology and surface contamination. A simple model is introduced and used to explain the process of arc erosion and contact resistance degradation during testing