Study of the decomposition of wet SF6, subjected to 50-Hz ac corona discharges

Abstract
Mixtures of SF6 (100 kPa≤PSF6≤400 kPa) and water (concentrations ranging from 240 to 2000 vpm) have been submitted to point‐plane 50‐Hz ac corona discharges. The only stable gaseous by‐products detected, either by gas‐phase chromatography or gas chromatography–mass spectrometry techniques, were SOF2 and SO2F2. The variation of their concentrations as a function of the discharge current value (3–25 μA rms), the charge transported (0.15–1.5 C), the water content, the SF6 pressure, and the gap spacing (1.5–5 mm) have been studied. The results indicate that, at least in our experimental conditions, the 50‐Hz ac corona discharges behave more like negative than like positive dc corona.