Dielectric recovery of an axially blown SF6-Arc after current zero: part I-experimental investigations

The results are presented of a model experiment to investigate the dielectric recovery of an axially blown sulphur hexafluoride (SF₆) arc after current zero. With the aid of Schlieren pictures and interferometry, the temperature decay after current zero is observed up to the point of complete recovery of the gap. The dielectric recovery is directly measured by applying voltage pulses across the gap which causes breakdown at different times after current zero. Residual charges, which play a role in the early recovery phases, are detected using a specialiy developed technique. Variations of the shape of the voltage pulses and the geometry cause characteristic changes of the recovery, which support the interpretation of the experimental data.