Experimental and Theoretical Investigations of Flashover Properties of SF6+CCl2F2 Gas Mixtures

SF6+CCl2F2 gas mixtures are regarded as one of the likeliest candidates as an alternative to SF6 as a dielectric gas. This paper reports experimental and theoretical investigations of the flashover properties of SF6+CCl2F2 mixtures. Measurements under a quasi-uniform electric field show that these mixtures have greater flashover voltages than either of the component gases for every mixing ratio examined; an advantage when using the mixture as an insulator. The properties of the mixtures are discussed from three different approaches, and it is concluded that the Boltzmann equation approach gives the values which agree best with the experimental values. One of the main causes of the enhanced flashover voltages lies in the change in the attachment coefficients produced by mixing. This unique property is explained theoretically for the first time.