Arcing Contact Materials, Cu, Cu Alloy, and Cu-Refractory Composites

Definition

Copper has very good electrical and thermal conductivity. Its low cost compared with silver make it a possible arcing contact material in some designs. Cu and Cu alloys such as brass (CuZn) or bronze (CuSn) are commonly used for conductors but generally do not perform as arcing contact tips because of contact resistance and welding concerns. Cu/W composites are the most common arcing contacts for high current switching up to several thousand amperes in vacuum, oil and SF6 switches. Cu/Mo and Cu/WC can perform similarly but less popular nowadays.

Scientific Fundamentals

When copper is used as an arcing contact, the high temperature arc can melt the contact severely and cause strong erosion and contact welding. If this occurs in air, copper is also oxidized to form high-resistance copper oxides. Therefore, for copper to be suitable, the design must have high contact force to reduce contact resistance and wiping action to mechanically wear out the oxide products. We see this...