Dielectric properties of N/sub 2//SF/sub 6/ mixtures for use in GIS or GIL

As an alternative to the insulating gas sulfur hexafluoride (SF/sub 6/), gas mixtures have been analyzed for use in high-voltage gas-insulated switchgear or transmission lines (GIS or GIL). The main component of gas mixtures is nitrogen (N/sub 2/) with various slight admixtures of SF/sub 6/. The investigations were undertaken on real technical arrangements with the aim of arriving at design fundamentals for high voltage installations. These fundamentals were confirmed and verified with the aid of various high-voltage tests on GIL constructions. The insulating properties of the gas mixtures are examined under various voltage applications in comparison with pure SF/sub 6/ insulation.