Pre-breakdown leakage current of tangential dielectric interfaces with different coupling pressures

One of the most important part of joints is the interface between the cable and the joint insulation. This region is particularly critical due to the presence of a strong tangential electric field, and the possible imperfect matching of the surface properties. The efficacy of such dielectric interface is influenced by several parameters, among which the clamping pressure has a major role in ensuring a proper mating of the surfaces. Therefore, this work investigates pre-breakdown events on dielectric surfaces under different pressures, in an attempt to develop a tool for online condition monitoring of HVDC joints. Results show that monitoring of leakage current on dielectric surfaces can be a viable way to detect pre-breakdown conditions in HVDC cables.