Development of PD Detection Method for Long-Distance Transmission Cable Lines

Abstract

Since a new method has developed on partial discharge (PD) detection from insulation joints (IJs) in long-distance XLPE cable lines, the PD measuring tests using this technique have come into common use for confirming the soundness of the lines. This method we call S. P. O. M enables us not only to detect PD safely and easily but also to calibrate the detection sensitivity using the indirect calibration from metallic-foil electrodes attached on both insulated surfaces of an IJ. Although PDs from normal joint (NJ) cannot be detected at NJ, attenuated signals transmitted from NJ can be detected at adjacent IJs at which calibration of detection sensitivity is also possible considering the attenuation constant of the cable line. The paper describes the principle of this method in IJ, and some applications to NJ and terminations considering the correction factor K which we defined for indirect calibration.