A New Automated Test Equipment for Measuring Electrical Contact Resistance of Real Size Rivets

It is well known that electrical contact resistance influencing factors include not only the contact material physical characteristics, contact type (sphere-flat, flat-flat), the contact surface status (clean, contaminated), but also contact current and mechanical load during measuring. Electrical contact material industry has considerable trouble with batch consistency check of rivet contacts. An automated test equipment and a test method have been described that make it possible to measure the electrical contact resistance of many real size rivet-type contacts with shank diameters 1~4mm at small contact loads with high efficiency. A stainless steel hemisphere with gold coating is designed as standard indenter; meanwhile the alternative choice would be the sphere-flat, flat-flat and sphere-sphere rivet contact pairs. Firstly, the voltage vs. current characteristics of AgCdO rivets is tested under different constant contact force. Secondly, the relationship between contact load and contact resistance during loading and unloading is investigated explicitly with different current. Furthermore, the effect of surface roughness and cleanness on the contact resistance is analyzed by comparison with normal and polished rivets, and those of long term exposure to the air. This equipment can be used for finding out the contact resistance consistency of batch contacts effectively for statistics analysis. But it also helps for the research work on the affecting factors of electrical contact resistance of stationary contacts.