The life of impregnated paper

A series of accelerated life tests on 14 different oils as used for the impregnation of one grade of cable insulating paper is described herein. Complete absence of gaseous ionization was insured in these tests. It is shown that there is a definite relationship between the life of impregnated paper under stress, and the capillary constant of the oil. With oils of one definite type, the life of the paper increases with penetrative power. Between oils of different types, there may be differences in the relation of penetrative power to life. The influence of dielectric loss on life is negligible, and the values of power factor during life tests appear to have no relation to life.