New approach in partial discharge diagnosis and maintenance of 22.9 kV XLPE power cables in service

Partial discharges (PDs) are one of the main causes of cable fault. Early detection and pre-analysis of PD characteristics are paramount in preventing cable breakdown. This paper analyzed the PD characteristics of 22.9 kilovolts (kV) calculated nerve conduction velocity (CN-CV) cross-linked polyethylene (XLPE) cable subjected to various artificial defects, based on the maintenance method by PD diagnosis. Various artificial defects were created in a 3-m CN-CV test cable to which a power frequency voltage of 60 hertz (Hz), 13.2 kV was applied. To compare the PD characteristics difference by cable length, a 3-m cable specimen was connected to a 70-m three-phase cable system using a high-voltage mating connector. A measurement unit and a high-frequency current transformer were used for PD data acquisition. As a result, different PD characteristics were found in each defect type, which provided better understanding of the PD phenomena. A maintenance method of 22.9 kV XLPE power cable through PD diagnosis was developed from the data obtained, which will help to ensure greater accuracy in the on-site diagnosis of a cable in service.