Experimental study on electric resistance of tilted contact in air circuit breaker

Due to the structure of multiple movable contacts in parallel in Air circuit breakers, the outer movable contacts tilt seriously when enduring the large short-circuit current. This paper is aimed to investigate the resistance of the tilted contact. A new designed experimental setup is built. Especially, the tilt angle and the contact force are able to be adjusted. Based on the measured results, it is found that the contact resistance is increased seriously when the movable contact starts tilting. After the contact type changing from the line contact to the point contact and the contact center offsetting to the edge of the movable contact, the contact resistance is increased gently with the tilt angle. At that time, the contact resistance is about 2.8 times of that without tilting, in the case that the contact materials are AgW50 and AgNi30, and the contact force is 105N.