Contact Material Solutions for LED Lamp Application

Lighting systems - such as LED - provide high inrush currents due to the capacitive behavior of their ballasts and drivers. Field problems of relays and switches failing due to tack welding are reported. Silver nickel (AgNi), silver zinc -oxide (Ag/ZnO), silver tin-oxide (Ag/SnO₂) and their combinations are widely used as contact materials for such applications.In this work the inrush behavior of different LED lamp types was characterized for a better description and understanding of the problem. Based on these studies model switch tests, focusing on the sticking tendency of typical contact material combinations, were performed under capacitive load simulating worst-case LED inrush currents. Metallurgical analysis on different switching probes after test were applied to explain the observed behaviors.The provided work can be used as a guideline for contact material selection in switching modern lighting applications.