Polarization and space charge behavior of unaged and electrically aged crosslinked polyethylene

The behavior of crosslinked polyethylene (XLPE) for Hv cable insulation under electrical stress is discussed in the paper, referring to specimens unaged and electrically aged. Polarization and space charge features are considered. The behavior of the examined insulation is evaluated through the 'universal' model for polarization and space-charge associated quantities, such as the de threshold for space charge build up and the total charge accumulated into insulation. It is shown that aging affects the magnitude and the frequency of low and intermediate frequency polarization peaks, as well as the magnitude of accumulated space charge and threshold. Charge injected or formed in the bulk, as well as microstructural modifications, could explain changes of polarization and space charge magnitude with aging.