The relationship between partial discharge behavior and the degradation of 10 kV XLPE cable joints

The failure rate of XLPE (Cross-linked polyethylene) cable joints is higher than that of cable in distribution systems due to bad environmental conditions, improper installation, and aging. To evaluate the failure and degradation of a cable joint via partial discharge (PD) detection, a 10kV XLPE cable joint was selected as the experimental sample, which was found partial discharge by field testing under damped AC voltage. An accelerated degradation experimental platform was set up for the 10 kV cable joint to simulate the cable operating conditions in the laboratory, and the PD behavior was monitored using a high frequency current transformer under different voltages and currents. The results indicate that the PD behavior is clearly affected by the voltage, current and aging time for the air-gap defect inside the joint. The degradation of the XLPE cable joint can be well characterized by the PD trend. Based on these results, a parameter is proposed for joints condition evaluation, which is the ratio of the PD magnitude between an interval time and named as a significant growth factor.