Experimental Investigation on Transition Characteristics of Arcing Stages Under Transverse Magnetic Field

Transverse magnetic field (TMF) contacts can prevent local overheat by creating a TMF and driving the vacuum arc to rotate around the contact periphery, thus improving the breaking performance of vacuum circuit breaker. The arcing behavior and the transition between arcing stages have great influence on the heat distribution on the contact surfaces, and they will finally affect the interruption at current zero. In this paper, a demountable vacuum chamber was used to investigate the arc behavior between two kinds of TMF contacts. A digital high-speed camera was used to record the arcing process. By combining the arcing appearance with arc voltage waveform, the arcing process was divided into four stages: initial expansion stage, arc instability stage, arc motion stage, and diffuse stage. The voltage characteristic and arc appearance of each stage were summarized and analyzed, and the transition condition between different stages was acquired. Moreover, the influence of current level and contact parameters on the duration and transition moment of each stage was also studied. The experimental results indicate that the initial stage is influenced by the arc ignition mode, whereas the arc motion and diffuse stage are significantly affected by the current level, contact type, and diameters. With the increase of peak current level, the duration of arc motion stage will increase, while the transition moment from arc motion to diffuse stage will move toward current zero.