Water trees conversion in field-aged XLPE

Different field-aged XLPE (cross-linked polyethylene) samples having opposite characteristics have been investigated. Studies of water tree growth and AC breakdown, and an examination of samples peeled-off from a 6-year field-aged cable an (HQ3) and laboratory aged have been carried out. The results obtained confirm the results obtained with cable HQ3 did not differ much in comparison with previous results on cable HQ4. The lower water or microcavity content, and the greater impurity concentrations and water tree density of cable HQ3 did not help to obtain water tree convertion into electrical trees. However, it is confirmed that laboratory and field water trees behave much more as dielectrics or are poorly conductive, and that laboratory accelerated aging conditions are not necessarily representative of what happens in the field. >