Morphology of forcing interruption arc of DC vacuum arc

With the applications of DC270V system in aviation field, the demand for DC switch has increased. At present, DC switch is mostly air switch, its switching capacity is small. For high capacity DC switch, vacuum switch has many advantages. According to the experiments of short gap vacuum DC interruption on DC270V system for aviation, the arc voltage and current characteristics of DC arc forcing interruption are analyzed. The impacts of the circuit parameters on the current rates di/dt, overvoltage rates dv/dt and their coupling situation are discussed. Under the same test current, the dynamic characteristics of arc diameter are studied. In forcing phase, the arc diameters of butt contacts decrease smoothly, while the AMF arc changes little, and has a sharp shrink before it quenches. Arc diameter increases slightly with the increase of the test current. At arc ignition stage, the arc diameters of butt-type contacts increase logarithmically, while the AMF arc is unchanged. The function of butt contact arc diameter is obtained. The arc diameter of plate contact is larger than that of the AMF before the forcing current injects.