Degradation and electrical behavior of aged XLPE cable models

Results of DC electrical conductivity measurements performed at different aging times on cross-linked polyethylene (XLPE) cable models subjected to thermal and combined thermal-electrical stresses are discussed. It is shown that the variations of electrical conductivity with aging time are related to those of other properties (density, crystallinity, electric strength, and microstructure) and hence to the aging processes. Electrical conductivity is shown to be a bulk property well able to indicate the degradation of an insulating material due to electrical and thermal stresses, even if the failure due to electrical stress is primarily a localized phenomenon