Study on SF6/N2 gas mixture breakdown characteristics in the presence of a free metal particle

Sulfur hexafluoride (SF
₆
), the widely used insulation medium, is a strong greenhouse gas. The SF
₆
/N
₂
mixture is expected to be an alternative gas and has been used in power equipments due to the low liquefaction temperature and environmental impact. In this paper, SF
₆
/N
₂
gas mixture breakdown characteristics are studied with a lifting metal particle in the gap. The distorted field distribution is calculated by finite element method (FEM). The critical electrical fields for both the static breakdown and breakdown in the particle motion are obtained from the streamer criterion. The results show that the critical distance for the breakdown in motion decreases with increasing SF
₆
gas fraction and pressure, and it appears a saturation with high SF
₆
gas fraction and pressure.