Decomposition characteristics of SF6-N2 gas mixtures under corona discharge

SF6-N2 gas mixture has been a potential replacement for pure SF6 in the gas insulated switchgear (GIS) but the relation between the decomposition of SF6/N2 mixtures and insulation defects, which contributes to promote the practical applications, has not been understood clearly. By the established experiment platform, this paper investigates the SF6-N2 gas mixtures decomposition characteristics under corona discharge generated with a point-to-plane electrode under different applied voltage, SF6 mixtures pressure and moisture contents. Partial discharge energy and charge have been monitored by the on-line insulation diagnosis system PDCheck. And the Gas Chromatography (GC) has been used to detect the decomposition products. The result indicate that the main by-products of SF6-N2 mixtures include SOF2 and SO2F2 under corona discharge. In addition, the total yield of the by-products is approximately linear with the discharge energy and the ratio of φ(SOF2)/φ(SO2F2) can act as the characteristic parameter of the corona discharge.