Characteristics of Lightning Impulse Corona Discharges in SF6/CO2 Mixtures

초록

This paper presents the experimental results on the prebreakdown characteristics in SF6/CO2 gas mixtures under a highly non-uniform electric field. The impulse pre-breakdown develop-ments are investigated by the measurements of corona current and light emission images. As a result, the prebreakdown development mechanisms for both the positive and negative polarities are fundamentally same. The first streamer corona is initiated at the tip of needle electrode, and the leaders develop with a stepwise propagation and bridge the test gap. The pause time of leader pulses in the positive polarity is significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity. The discharge channel paths in the positive polarity were zigzag. On the other hands, the leader channel in the negative polarity was thicker and brighter than that in the positive polarity.