Behavior and Partial Shorting of Long Gap DC Free Arc between a Pair of Parallel Conductors

Abstract

The behavior of arc spot and arc column on long gap DC free arcs between a pair of parallel rod conductors were analyzed quantitatively from two orthogonal views by two high-speed video cameras. In addition, the partial shorting phenomenon, which occurred between the arc column and the rod conductor, was studied experimentally. The pair of iron or aluminum parallel rod conductors was arranged horizontally with the gap of 1.6m and the movement sections for arc spots on the conductors were set to be 1m. Objective arcs were ignited with the current in the range of 0.1 to 8kA and the duration time of 0.3s. When the arc spots moved to the load side after the arc ignition, the middle of arc column hardly moved with the arc spots, that is, it always remained behind. Therefore the partial shorting, which brought about the jumps of the arc spot to the power source side, frequently occurred between the arc column and the rod conductor as the arc current increased. To study the occurrence conditions of above partial shorting, the relationship between the path length of disappeared arc column and the straight distance was investigated. As the result, it was clarified that this relationship was almost in a direct promotion. Accordingly it was suggested that this relationship could be used as a certain index about the occurrence conditions of partial shorting.