Basic Investigations on the Behavior of Advanced Ag/SnO2 Materials for Contactor Applications

Higher power density and longer electrical lifetime at the same time are the main technical targets in development of contactors. Therefore, a close matching of contact material and switching device as well as the understanding of the material-device-interactions is necessary to achieve those demands. The paper will demonstrate the general influence of different material parameters based on Ag/SnO₂ in model switch tests and off-the-shelf contactors under various load conditions. The basic tendencies of the materials can be seen in both test series, but are partially counterbalanced by device specific effects like electrodynamic lift-off, unbalanced erosion between single pairs of contacts or the rise in contact resistance. Since under different load conditions welding, erosion and contact resistance vary, contact materials with 12-14% metal oxide content and special additives appeared to be the best choice for contactor development.