The Effect of Voltage Waveform on Phase-Resolved Electroluminescence Measurements

Space charge plays a significant role in long term electrical degradation of polymeric insulation in high voltage cables and consequently there is growing interest in the measurement of the energy dissipation of mobile and trapped charges in dielectric molecules. The dissipation process is associated with the emission of visible photons, a process known as electroluminescence (EL) and can be used, potentially, as an indicator for the initiation of electrical ageing of insulation. This paper presents the experimental work undertaken to examine EL from different ac applied voltages. Using a charge coupled device (CCD) detection system, the setup allows the determination of the light emission occurrence respect to the applied field. Phase-resolved EL measurements have been obtained using sinusoidal, triangular and square voltages.