Effect of frequency on XLPE cable insulation at high electric field

Electroluminescence (EL), the emission of light in dielectrics subjected to high electric stress, is a very sensitive technique to detect space charge injection and the very early stages of insulation degradation. In this paper the EL technique is employed to determine the effect of frequency in the range of 5 to 600 Hz on unaged and aged crosslinked polyethylene (XLPE) insulation of underground high voltage cables. The number of EL pulses emitted from XLPE and the area of the space charge region simultaneously obtained by the PMT and CCD camera are studied as the frequency of the ac voltage is varied between 5 and 600 Hz. The implications of the frequency range on diagnostic tests performed on the polymeric insulation of underground power ca es is discussed.