Analysis of Photoluminescence in Thermo-Electrically Aged Cross-Linked Polyethylene Cables

Photoluminescence measurements have been carried out along the radius of the insulation of un-aged and thermo-electrically aged HVAC cables. A specific emission, with maximum at 400nm has been isolated in the cross-linked polyethylene insulation in the vicinity of the semi-conducting screens. Complementary measurements on lab-compounded samples were carried in order to unravel the nature of the emitting species. It is shown that the antioxidant of the semi-conducting screens is at the origin of this emission and exhibits significant diffusion within the bulk of the insulation. Specific signatures have also been observed on cables having undergone significant yellowing.