Current chopping phenomena in SF6 selfblast circuit breakers

In SF 6 selfblast circuit breakers the arc energy provides a current dependent pressure rise in the upstream volume. For successful interruptions for smaller currents a current independent gas flow is necessary. The gas flow can cause current chopping when small inductive currents are interrupted. In the present paper chopping phenomena are investigated experimentally. Arc time constants are determined by current step experiments. A two-pole arc model is used for the simulation of the observed phenomena