Experimental investigation of triggered vacuum arc behavior under different TMF-AMF composite contacts

Using magnetic fields to control the vacuum arc is a major way to improve the breaking capacity of vacuum interrupters. Besides the single transverse magnetic field (TMF) and single axial magnetic field (AMF), new type of TMF-AMF contact structure has been put forward to control the vacuum arc in recent years. In this paper, two different structure contacts are used in experiments. The arc evolution was captured by an ul-trafast digital video camera, and at the same time the arc current and arc voltage wave was recorded. The experiment was conducted under current ranging from 5kA to 20kA (rms) and 10mm of gap distance. The results showed that under low current, the arcs of the two contacts both kept diffused and rotating. Under high current (I=20kA), the arc of TMF-AMF contact with 6 slots was constricted and rotated on the plate and the melting was uniform and slight. As for the 8 slots contact, the arc was constricted but did not rotate which resulted in significant melting in the local region.