Dielectric breakdown of sulphur hexafluoride

THIS ARTICLE presents some of the anomalies in the dielectric breakdown of sulphur hexafluoride as functions of pressure and electrode separation in a nonuniform field. At atmospheric pressure, this gas has unexpectedly high 60-cycle breakdown voltage for large gaps. At larger spacings, the spark-over voltage may increase more than proportional to the spacing, rather than levelling off as is more usual. This results in an inflection in the curve of breakdown voltage versus spacing, Figure 2. In this case, corona precedes spark-over.