Influence of impurities and additives on positive streamers in paraffinic model oil

This paper presents an experimental study of positive streamers in paraffinic model oil in a point-plane gap. The investigation was performed concerning the influence of voltage, impurities and additives. It was seen how increased voltage changes streamer shape and speed resulting in different propagation modes. Carbon particles markedly reduce inception, breakdown and acceleration voltages, while dissolved gases/air have little effect on these voltages. A low ionization potential additive decelerates the streamers, while an electron scavenger shows an increase in streamer velocity. The correlation between propagation velocity and streamer´s branching is discussed.