Effect of nanofillers in HVDC insulations on surface partial discharge activity

One of the most important parts of HVDC cable systems are terminations and joints, since they are often points of failure. The field distribution and dynamics of those regions are strongly influenced by the electrical properties of surfaces, due to the presence of strong tangential electric fields able to locally incept surface partial discharges or breakdown. This paper has the main purpose to assess the influence of nanofillers on the mobility of electrostatic surface charge buildup, and the effects on Partial Discharge inception and repetition rate characteristics of HVDC dielectrics. Flat specimens were produced and tested using different thermoplastic dielectrics, some of which belonging to the family of nano-filled materials. Results show that nanofillers have a profound effect on electrostatic charge buildup, strongly reducing their mobility.