A Dampness Discrimination Method for MV Power Cable Joints Based on PDC Testing Under Thermal Excitation Conditions

The penetration of moisture into power cable joints accelerates cable insulation degradation, ultimately leading to cable breakdowns and power outages. The determination of whether environmental moisture has penetrated an insulation interface and the discrimination of dampness status are, thus, significant tasks in cable operation, maintenance, and management. Therefore, a dampness discrimination method based on polarization and depolarization current (PDC) testing under thermal stimulation is presented here. Initially, a working principle of the PDC testing method for detecting moisture in cable joints is developed. Subsequently, a thorough description of the principle of dampness discrimination in cable joints is provided based on PDC testing under thermal stimulation. This analysis reveals that thermal stimulation may alter the phase state of water and the interface contact state between cross-linked polyethylene (XLPE) and silicone rubber (SiR), decreasing the conducting current of the cable. In addition, finite element simulations are employed to determine the parameters for the thermal stimulation methods. Finally, experimental results confirm the effectiveness of the proposed method in accurately identifying dampness defects in cable joints.