Investigating the effect of additives for high-voltage polymeric dc cables through space charge measurements on cables and films

This paper presents the results of space charge measurements carried out on specimens of cross-linked polyethylene, with and without additives, obtained by a press-molding procedure, on medium voltage cables having the same insulating material and on films cut from cables. It is shown that the behavior of the additives can be singled out as well resorting to space charge measurements at high electrical field on films (either press-molded or cut from cables) or at low field on untreated cables. This proves that the considered additives are efficient in reducing space charge clustering in the presence of both injected charges at high field and charges deriving from cross-linking byproducts, and that the investigation carried out on films can provide results useful to evaluate cable behavior, thus saving testing efforts.