Research on impact of opening velocity in DRM tests of SF<inf>6</inf> high voltage circuit breakers

Abstract

High voltage circuit breakers are most important protective device in power system. Dynamic contact resistance measurement (DRM) is considered to be an effective assessment technique for contact ablation which has been widely used for many years. However, the contact resistance curves will be influenced by many factors, such as injected current and velocity. In power systems, circuit breakers often work under non-normal conditions, like the fatigue of spring and the insufficient of hydraulic pressure. These conditions will decrease the opening velocity and then greatly affect the stability of the curve as well as the average contact resistance during the DRM tests. Based on collecting the contact resistance curves in different opening velocities, it is found that the values of contact resistance increase with the growing of the opening velocity. Opening velocity will affect the frictional heat and effective contact area of the contact, and the two factors are discussed by the finite element model and micro measurement in this paper. The finite element simulation model can be used to prove that the frictional heat can be ignored, while the contact resistance with different velocities is determined by the changing of effective contact area.