What kind of material is the finger spring usually made of?

At present, GIS mainly uses three spring finger materials, namely chrome-zirconia-copper (standard ASTM-C18150). Beryllium cobalt copper (ASTM-C17500) and beryllium copper (ASTM-C17200). As can be seen from the table below, chromium-zirconium-copper has the highest conductivity from highest to lowest, while beryllium-copper has the lowest. From high strength to low strength, chromium - zirconium - copper is the lowest and beryllium - copper is the highest. The higher the conductivity, the lower the strength of the material. High conductivity spring refers to low strength, low contact pressure, can exceed the flow of beryllium cobalt copper spring finger? It has been mentioned in the literature that the allowable current density of beryllium cobalt copper is twice that of beryllium copper.

The spring contact fingers of beryllium-cobalt-copper and chrome-zircal-copper of the same size were installed in the same location by multiple temperature rise tests on the GIS. The test current is 2000? 4400 a. It is found that the temperature rise of the contact surface of the chromium-zirconium copper spring finger is 4-10°C lower than that of the contact surface of the beryllium-cobalt-copper spring under the same current. Tests have demonstrated that chromium-zirconium-copper springs with high conductivity materials have significantly higher electrical conductivity than beryllium-cobalt-copper springs with lower conductivity materials, although they have lower contact strength and lower contact pressure.