Investigation of partial discharge propagation in cross-bonded HV cable systems

In order to address the detection and localization of partial discharge (PD) in cross-bonded (CB) high voltage (HV) cables, this paper investigates the characteristics of PD propagation in CB HV cables. On-line PD detection and location in power cables has been a research topic for many years. The issue has not been solved due to surrounding interference and complicated propagation modes in cable joints. It becomes even more complex with CB cables. The main challenge to PD monitoring of CB cables is as a result of the interconnectedness of the sheaths of the three single phase cables. The cross-bonding of the sheaths makes it difficult to localize which of the three phases a PD signal has emanated from. Co-axial cables are used to connect cable sheaths to cable link boxes, for ease of installation and protection against moisture. A second challenge is, therefore, the coupling characteristic when a PD pulse propagates in HV cable joints and the co-axial cables, making PD detection and localization more complex. The paper presents experimental investigations into PD pulse coupling characteristic between the cable center conductor and the sheath and the behavior of PD pulse propagation in CB HV cables, which can be used for PD localization in CB HV cable system.