EFFECT OF MODIFIED SURFACE-STRUCTURE OF IMPREGNATED POLYPROPYLENE FILM ON CAPACITOR DIELECTRIC-PROPERTIES DURING THERMAL AGING

The results of ageing tests of biaxialy oriented impregnated capacitor polypropylene films with modified and unmodified surface structure ar e presented in this paper. The temperature dependence of factor D = ta n delta(1)/tan delta(0) (where tan delta(1) and tan delta(0) relate to impregnating fluid aged with and without polypropylene film, respecti vely), the relationship between factor D and the aromatic content of i mpregnating fluid and time dependence of dielectric strength for both types of film are presented. The possible destroying mechanism of the capacitor dielectric system is given.