Effect of cellulose particles on streamer initiation and propagation in dielectric liquids

The effect of cellulose particles on streamer and breakdown phenomena in a synthetic ester and a mineral oil was investigated using a non-uniform point-plane electric field and a uniform plane-plane electric field under standard lightning impulse voltages. Oil samples were prepared to be low and high contamination levels according to CIGRE brochure 157. A multi-frame high-speed camera was used to record the streamer phenomena. By analysing the breakdown voltage and streamer characteristics, i.e. length, velocity, initiation time and propagation time under both positive and negative polarities, the particle effect on streamer development and breakdown in liquids is revealed. The results show that the increase of cellulose particle contamination level does not affect streamer propagation in non-uniform electric field, but promotes the streamer initiation leading to lower breakdown voltages in uniform electric field.