The erosion and arc characteristics of Ag/CdO and Ag/SnO/sub 2/ contact materials under DC break conditions

Abstract

Break operation studies have been conducted upon Ag/CdO and Ag/SnO/sub 2/ contact materials under dc conditions between 1-16 A. The apparatus used allows contact materials to be continually tested with a controlled break velocity. Results are presented on erosion data in terms of mass transfer. Surface analysis methods are used, scanning electron micrographs reveal distinct structures and areas on the contact surface, and elemental analysis (EDS) shows migration of metal species with current. The metal-oxide used in the contact is shown to influence the arc and erosion characteristics of break only operations. The Ag/CdO contacts exhibit lower erosion than Ag/SnO/sub 2/ contacts under these controlled conditions.