Accelerated life testing of EPR-insulated underground cable

A description is given of an accelerated cable life test developed by R. Lyle and J.W. Kirkland (see IEEE Trans. on power apparatus and systems, vol. PAS-00, p.3765, 1981). The use of the method to study medium-voltage ethylene-propylene rubber (EPR) insulation for underground distribution is reported. The program began with the testing of commercially available cable insulated with crosslinked polyethylene (PE) and with tree-retardant crosslinked PE in order to provide internal controls for comparison with EPR constructions and determine if advances in both polymer quality and extrusion technology have resulted in improved test performance since the publication of earlier data. The results show that a high-quality EPR insulation resisted the combined stresses of moisture, heat, and voltage better than the other cables. it was also found that EP insulation does not have superior resistance to tree initiation and growth, that there is an optimum level of kaolin filler, and that the limiting factor in EPR test performance is the corrosion resistance of the conductor.<>