ELECTRIC STRENGTH OF VARNISH FILMS

Abstract

IN a paper entitled “Intrinsic Electric Strength and Conductivity of Varnish Films and their Variation with Temperature” (J. Inst. Elec. Eng., 89, Pt. 1, No. 23 ; November 1942), A. Morris Thomas and Miss M. V. Griffith discuss recent advances in the theory of the intrinsic electric strength of solids, and describe methods for the preparation and testing of samples of baking insulating varnishes and shellacvarnish films for the determination of their intrinsic electric strength. The varnishes tested were a clear baking oil insulating varnish, a black baking bituminous insulating varnish, a synthetic-resin insulating bakelite varnish, and a pure de-waxed lemon shellac varnish.