Evaluation of service aged 35 kV TR-XLPE URD cables

This paper provides information on aging of URD cable insulated with tree-retardant crosslinked polyethylene (TR-XLPE) compound, installed in a typical utility environment. Numerous evaluations were performed on samples of the cables aged up to 7 years in-service. AC and impulse voltage breakdown data are compared with data for similar 35 kV ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE) insulated cables removed from the same utility system. The data show that, to date, the rate of degradation of TR-XLPE cables is less than that of the EPR and XLPE insulated cables. Extrapolation of the data, assuming the same rate, indicates TR-XLPE cable will have the longest life.