Switching performances of hollow contact rivets

A possibility of reducing contact material requirements in relays by application of hollow contact rivets was investigated. In the existing type of relays, standard massive contacts were replaced by specially prepared hollow contacts, shaped in the form of shells made of thin plates of the contact material. The results of contact performances of hollow and massive contact rivets, applied in the same type of relays for tests were compared. Evaluation of bouncing, temperature rise on contacts, arc duration at break, switching capacity, and electric contact life were performed according to IEC standards. Good or even better performance of hollow contacts were obtained. After tests some microscopical examinations of contact surfaces indicate erosion characteristics at higher electrical loads.