Experience with dielectric response measurements on oil-paper insulated cables

Abstract: Deterioration of the underground power cables insulation has been established to be caused by electrical, thermal and environmental stresses. With the degradation of dielectric strength of the insulation, the underground cables will not be able to function optimally or as planned. As a supplement to the existing dissipation factor and other conventional cable diagnostic measurements, the Decay Voltage (DV) and the Return Voltage (RV) measurement technologies are currently being proposed for non-destructive diagnosis of cable insulation. The main purpose of this paper is to present results from laboratory measurements of DV, RV and Polarisation and Depolarisation Current (PDC) on a number of samples of oil-impregnated paper insulated cables. Comparison of these results has also been made with the conventional dissipation factor measurement data for the same cables. 1