A comparison of the erosion and arc characteristics of Ag/CdO and Ag/SnO2 contact materials under DC break conditions

Break operation studies have been conducted upon silver metal-oxide (Ag/MeO) contact materials under DC conditions between 1-16 Amps. The materials used in this study are Ag/CdO and Ag/SnO/sub 2/ typically used in low voltage switching. The apparatus used in the study has been previous presented and allows contact materials to be continually tested with fully controlled break velocity. The results presented include erosion data in terms of mass transfer and surface analysis using scanning electron microscopy. Scanning electron micrographs reveal distinct structures and areas on the contact surface. Elemental analyses (EDS) was also conducted which show migration of metal species in the Ag/MeO, with various current loads. It is shown that the type of metal-oxide used in the contact significantly influences the arc and erosion characteristics on break operations. Contacts have been shown to exhibit different erosion/deposition characteristics at particular current on break operations. Erosion and deposition of the contacts on break have been related to two parameters: arc energy and arc duration.