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

Abstract

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/SnO 2 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.

Forming ohmic Ag/SnO2 contacts

“…This is the main reason behind the investigations carried out on the electronic features of the platinum-, gold-, and silver-SnO 2 contacts [9][10][11]. Moreover, Ag/SnO 2 -based cermet segments have been proposed as contactor points [12] and studies on the electric conduction mechanism through the Ag/SnO 2 junctions may assist structure optimization in these high current density components.…”

Effect of SnO₂ Particle Size on Properties of Ag-SnO₂ Electrical Contact Materials Prepared by the Reductive Precipitation Method

“…Silver-tin oxide composite materials have been widely applied to low voltage switch in the past two decades [1]. In practice, the advantages of eco-friendly, low temperature rising and anti-welding behaviors makes them the most attractive replacement for Ag-CdO electrical contact materials.…”