Comparison of the accelerated aging under different thermal cycles and voltages impulses in XLPE cables

This article summarizes the changes on the main electrical, physical and thermal properties of the crosslinked polyethylene (XLPE) employed as insulation of medium and high voltage cables, operating under multiple degradation factors, such as temperature, AC voltage and voltage impulses. A comparison of changes on the properties of different cables samples, 2 AWG copper conductor, 15 kV XLPE insulation, was made. Those samples were put under accelerated aging process, applying two types of thermal cycles; one denominated "On-Off' and the other denominated "Daily Load Cycle". Both cycles were combined simultaneously with 23 kV AC permanently, followed by the electrical stress associated to voltage impulse test at the end of each cycle. Two impulse wave forms were employed, the standard lightning impulse (1.2/50 mu s) and one non-standard voltage waveform impulse (30/110 mu s).