Investigation of attenuation characteristics of PD pulse during propagation in XLPE cable

Wave propagation characteristics of partial discharge (PD) pulses in underground medium voltage cables are important when online PD monitoring system is implemented for cable diagnostics and condition assessment. There are three important parameters that can influence the wave propagation characteristics along a cable. These are the length of the cable, cable loading conditions and propagation characteristics of the cable. Propagation losses occur in power cables as PD pulses propagate along the cable. Since different types of cables have different parameters, the wave propagation characteristics such as attenuation and propagation speed will also vary accordingly. This paper presents the results of an experimental study performed to investigate the attenuation behavior of PD pulses as they propagate along a medium voltage XLPE cable and undergo reflections. It is shown that PD pulses attenuate as these propagate and higher frequency components suffer more in attenuation. This in turn decreases the magnitude and increases rise and fall time of pulses.