AC breakdown voltage characteristics simulation of SF6/N2 in non-uniform field and extra high voltage

SF₆ is the most commonly used insulating gas in electrical systems. But In these days SF₆ mixtures and alternative gas has been studied because of global warming. so although many studies have been carried out about binary gas mixtures with SF₆, few studies were presented about breakdown characteristics of SF₆/N₂ mixtures. At present study the breakdown characteristics of SF₆/N₂ mixtures in Non-uniform field was performed. In this paper, breakdown experiment values and breakdown simulation values are compared. Streamer theory was used for predicting breakdown voltage. For accurate simulation field factor, this simulation apply E field utilization using cst program AC breakdown experiments in non-uniform field was performed to compare with the breakdown simulation values. The pressure range of gas mixtures was 0.4 MPa to 0.7 MPa. The rod-plane was used and mixture ratio is SF₆ 20% : N₂ 80%. The gap lengths is 10mm to 70mm. As pressure increase, this simulation value do not correspond to the experiment value. So this simulation apply to utilization factor using CST program. In the result, it was observed that breakdown voltage increase as pressure and gap lengths increase. But with gap lengths increasing, the breakdown voltage is saturated. So simulation need surface roughness factor.