Electrical performance of crosslinked polyethylene under uniform and divergent fields

This paper presents test techniques which enable electrical endurance characterization of HV cable insulating materials in relatively short times. Three crosslinked compounds are considered, i.e., two kinds of homopolymers, slightly differing in morphology, and a copolymer blend based on PE (polyethylene). The technique relies upon electric strength and life tests performed on plaques, subjected to uniform electrical field, and tree-inception tests, realized by needle-plane electrodes. The entire test cycle lasts ~500 h, but it proves to be able to distinguish among material performance not only in short times, but, probably even in the long run. In particular, it is shown that the copolymer blend behaves better, from the point of view of electrical endurance, than the homopolymers. It is thus emphasized that a test procedure as here proposed allows prompt feedback, which is fundamental for the technological development of insulating materials