Pressure effects and moisture penetration in mass-impregnated cable

Mass-impregnated cable or PILC (paper insulated lead cable) exhibits pressure effects under load variations. The pressure build-up in a cable is related to materials and design of the cable as well as to temperature and load. As one of the results, in some cables moisture can travel easily. This can cause early degeneration of the cable insulation and accessories. It thus enhances the risk of failures. The present paper describes a part of a larger research project that aimed at assessing the pressure effects due to load cycling on full size cables and the relation to moisture ingress. The experiment included a full short circuit test on five cables.