Dielectric and partial discharge investigations on aged medium voltage underground power cables

This paper investigates on dielectric and partial discharge (PD) condition of aged XLPE insulated, medium voltage underground cables rated 20 kV, acquired on-site. The extracted samples have suffered PD and failed at different instants. First, the cable samples are grouped as per their timeline of failure. Following this, the dielectric integrity of the cable samples are assessed through modern diagnostic test methods over wide frequency. This implies involving dielectric response analysis and PD measurements respectively. The dielectric integrity of chosen samples are ascertained through frequency dependent dielectric properties. The PD measurements include recording the PD level or apparent charge level (QIEC) of chosen samples and analyzing their respective phase resolved PD pattern. Following this, the information of real time PD signals are transformed to frequency domain and analyzed. Altogether, the findings from all these measurements collectively describe the characteristics of chosen cable samples. In conclusion, it is believed that such an attempt might provide a deep insight in improving the present interpretation strategies.