On a certain disadvantageous mode of the arc between cup-shaped contacts during high-current interruption in vacuum

The article presents research results of discharge development and are mode s of high-current vacuum arc between cup contacts with slots to generate a transverse magnetic field (i.e. contracts contracts). The peak value of the applied AC are current half-wave ranged from a few kA to 27 KA. Photograph s of the arc were taken with a high-speed framing camera at 10000 frames/s. It was found that the arc between cup-shaped contacts behave in a similar way in the following two cases: if the electrodes are separated shortly aft er the onset of the main current, and if the arc is created ar a fixed cont act gap. It was shown that, for both cases, there is a tendency to locate t he stationary anode spot inside the cup and the nr-ising stationary, constr icted arc mode, which is disadvantageous in terms of arc extinction.