Influence of contact material on the performance of a DC contactor

The influence of different silver/metal oxide contact materials on the performance of a DC-contactor has been evaluated in regard to service life, contact resistance and overtemperature behavior. It was found that the service life of contact materials from the group of silver/tin oxide contact materials is superior to the silver/cadmium oxide material. In regard to contact resistance and overtemperature behavior the conventional type of silver/tin oxide tends to be at a disadvantage in comparison to silver/cadmium oxide, while a silver/tin oxide based on doped tin oxide powder leads to improved results. The results obtained are discussed on the basis of effects taking place in the contact materials due to the action of the DC arc treatment.