Breakdown statistics for XLPE containing the volatile by-products of the cross-linking reaction

AC and impulse breakdown strengths have been measured on recessed samples of cross-linked polyethylene (XLPE) containing controlled amounts of the by-products (or residues) of the crosslinking reaction, i.e. acetophenone, cumyl alcohol, alpha methyl styrene, and cumene. The statistics used to describe the distribution of breakdown strengths are discussed. Weibull, Gumbel, and Gaussian statistics are compared. Other statistical distributions resulting from fluctuations in the character of the discharge sites at the metal-polymer interface are also examined. Despite the fact that a simple weakest link mechanism cannot be used to describe the breakdown strengths of recessed samples of XLPE containing the crosslinking residues, no reason has been found to discard the Weibull distribution. The results of this investigation can therefore be presented in tables of characteristics values and shape parameters