Investigation of dielectric behavior of thermally aged XLPE cable in the high-frequency range

The widespread use of crosslinked polyethylene (XLPE) in the wire and cable industry may be attributed mainly to its outstanding physical and chemical properties. However, it has been recognized that degradation of XLPE insulation during service, such as thermo-oxidation and water treeing, may lead to premature electrical breakdown of the XLPE insulation cables. Diagnostic measurements would considerably assist to distinguish between bad and still good cables. Estimation of the degree of aging is at present the most important task of diagnostic methods. This paper presents a study on the thermo-oxidation-induced changes in the dielectric properties of the thermally aged 3.3 kV XLPE cables in the frequency range from 70 kHz to 10 MHz.