Experiment on breakdown characteristics of SF6/N2 mixtures in short gap

Since SF₆ gas induces severe greenhouse effect, it became a common view that less SF₆ gas would be used in the future. Breakdown characteristics of SF₆/N₂ mixtures gas in short gaps are studied in this paper. Breakdown voltage of SF₆/N₂ has been measured in uniform electric field when the SF₆ gas mixture ratio is from 0% to 100% and the pressure is between 0.1MPa and 0.4MPa. Influences of gap distance and pressure on the insulation property of SF₆/N₂ are investigated, and the optimal SF₆ gas mixture ratio is found. Spectrometer is used to measure microcosmic parameters like electron temperature and electron number density when SF₆ and mixture gas are completely breakdown. Then the relationships between these microcosmic parameters and macroscopic parameters (pressure, SF₆ gas mixture ratio and gap distance) are established, and breakdown characteristics of gas are analyzed. The study shows that both pressure and gap distance have linear relationship with breakdown voltage of SF₆/N₂ mixtures gas. Considering security and environment protection, it is proposed that the mixture gas has optimal insulating properties when SF₆ gas mixture ratio is 20% Electron temperature drops with pressure increasing, while relative light intensity and electron number density both rises with pressure increasing in a uniform electric field and the pressure between 0.1MPa and 0.4MPa when the gas is completely breakdown. Both electron temperature and relative light intensity lise with SF₆ gas mixture ratio increasing, while the corresponding electron number density drops in 0.1Mpa.