High voltage research (breakdown strengths of gaseous and liquid insulators) and environmental effects of dielectric gases

Electron attachment rate constants for five halogenated ethylene compounds were measured in two background gases, and the corresponding attachment cross sections, sigma/sub a/(epsilon), were calculated. Electron attachment rates were also measured for two perfluoroalkanes, and the attachment cross sections calculated. Initial decomposition products of n-C5F12 are being studied. Breakdown strength shows strong dependence on the magnitude and energy dependence of the electron attachment cross section. The problem of compressibility of some dielectric gases is considered as well as the breakdown of several fluorochlorohydrocarbon gases. The effect of mixture components and proportions was observed on corona stabilization of breakdown. The applied testing concentrated on cylindrical geometry tests with smooth and rough electrodes to systematically determine optimum ternary mixtures of two attaching gases (SF6 and c-C4F8) with one moderating gas (either N2 or 1,1,1-C2H3F3 or CHF3).