Effects of aging on dielectric interfaces of cable accessories

Electrical breakdown at the interface of two dielectric surfaces is a major design consideration in underground cable accessories. The reliability of any given system essentially depends on its performance in aging. Several factors could affect the aging performance of a dielectric interface. The interfacial pressure will reduce with time because of the material aging and relaxation; as a result, the breakdown voltage may also change; finally, sticky aged greased interfaces could adversely affect the pull-out force for disconnecting a detachable connector. A series of aging experiments were carried out with laboratory molded slab samples simulating various dielectric interfaces of cable accessories. Results as obtained on the variations of the interfacial pressure, the breakdown voltage as well as the pull-out force will be presented and discussed.