Contaminated connector and surface atmospheric flashover phenomena: a preliminary investigation

Abstract

Contaminated connector and surface flashover has been shown to often catastrophically damage energy systems. A greater general understanding is needed to be able to design modem energy systems around this unique failure process. A flashover is a disruptive discharge through air around or over the surface of insulation produced by the application of voltage wherein the breakdown path becomes sufficiently ionized to maintain an electric arc. Flashover in and on insulators has in the past been shown to start near the interface between insulator, conductor and air (or some other insulating medium) and is known as the triple point. The focus of this initial study is on the adverse effects of flashover on thin polyester and polypropylene films cut to initial lengths and widths of 12"/spl times/3/4" respectively, representative of long path flashover in contaminated military and industrial systems. Flashover on the samples was initiated by the application of 2400 V/sub ac/. Preliminary results have shown that the thin polyester film is resistant to flashover formation and sublimates upon the application of the external AC voltage. However, polypropylene film was able to sustain the flashover without sublimating. Upon further investigation, the polypropylene would sustain flashover when scaled down linearly in voltage and length to a minimum of 150 V/sub ac/ and 3/4" length. These initial studies of AC flashover on rather long contaminated surfaces (resistivity of /spl sim/7 ohms/square) are to be extended to DC behavior as well as assessment of flashover robustness with increasing surface resistivity in order to allow improved connector and interface engineering design algorithms to be developed for future systems.