Electrical Investigations on the Interface between a FRP Tube and a Low-Density Polymeric Foam

The internal insulation of hollow-core composite insulators (HCIs) is typically realized with low-density dielectrics such as foams. The use of foams inside HCIs results in an interface foam-FRP material. The leakage current along an interface composed of an FRP material and a novel sort of polymeric foam was investigated experimentally, with a novel guard electrode arrangement embedded inside the interface, as well as with a FE simulation model. The experimental results indicate that the interface currents are in the picoampere range and that are affected by the homogeneity of the foam’s pore structure, differing from the simulated currents as much as one order of magnitude. The use of an adhesion promoter that enhanced the bonding increased the interface current in two orders of magnitude.