The effect of electrode construction in breakdown time lag of impulse breakdown in mineral oil

A breakdown time lag of uniform and nonuniform electric fields using point-plane and sphere-sphere electrodes in mineral oil was measured. The stainless-steel spherical electrode was 12.5 mm in diameter. The needle electrode was made of iron and its tip was electrolytically polished. The copper plate electrode measured 10mmx20mmx1mm. The effect on breakdown time lag wielded of differences in the distance between electrodes and applied impulse voltage revealed that the time lag was proportional to the applied voltage and the breakdown time lag of a nonuniform electric field was shorter than that of a uniform electric field. It was found that the breakdown phenomena in point-plane and sphere-sphere electrodes were respectively similar to a streamer-type breakdown and a streamer breakdown structure.