Study of DRM During Closing Period of High Voltage Circuit Breaker

Dynamic resistance measurement (DRM) has been used to diagnose the contact condition of high voltage circuit breaker for many years. However, only the resistance curves during opening period are regarded as valid, partly because the curves during closing period are easy to be disturbed by many factors, such as vibration, noise and velocity. According to Holm's theory, the contact resistance is inversely proportional to the contact force. In this paper, the contact resistance curves during closing period are studied, while a finite element model of the arc contact is developed and used to calculate the dynamic contact force. Based on the model, the inversely proportional relationship between the contact resistance and contact force during arc contact making process is verified. It shows that the resistance value becomes extreme high and will drop quickly when the arcing contact bounce off until the completion of arcing contact re-touching. In conclusion, the fluctuation of the contact resistance during closing process is attributed to the change of contact force and it is also meaningful and can be used to analyze the matching condition of arcing contact.