Streamer propagation and breakdown in transformer oil under overvoltage in semi-uniform gaps

This paper presents an experimental study about the influence of electrode geometry on streamer propagation in overvolted gaps in transformer oil. Experiments concern the measurements of time to breakdown and streamer visualization, either in point-plane or in semi-uniform gaps (parallel plates with a triggering point). Results show that the transition between propagation modes remarkably depends on the electrode configuration. It is concluded that this transition is determined by the “macroscopic” field distribution surrounding the streamer