Comparison of electroluminescence of different high voltage cable materials under identical experimental conditions

Polymers used in high voltage cables have excellent short term dielectric properties such as high dielectric strength, low dielectric loss and high resistivity. Nevertheless they can be vulnerable to long term deterioration due to the continuous application of high electrical stress. Detection of electrical degradation is usually achieved when ageing is already prominent, for instance when partial discharge activity exists. One possible approach to detect early electrical degradation of polymers is known as the electroluminescence (EL) technique. This paper places emphasis on the description of an experimental arrangement for this method. It also presents the temporal and spectral characteristics of EL emitted from two different types of polymers: low density polyethylene (LDPE) and polyethylene terephthalate (PET). Measurements are made at room temperature using several thin films of both materials under various AC stresses in a excellent electrical field configuration