The volumetric erosion of electrical contacts

This paper presents an investigation of worn electrical contacts, to ascertain the volumetric erosion changes. The main emphasis in this paper is on the measurement of volume relative to a contact support surface, allowing severely eroded contacts to be measured. A non-contact system is described, which allows contacts to be evaluated for volume change without the contact being removed from contact supports. The accuracy of the measurement method is discussed and results show how the volume measurement can be used to evaluate contact performance. Results are presented on the erosion characteristics of Ag/SnO/sub 2/ contacts used in automotive relays.