Theoretical Study of Dielectric Breakdown in a New Composite Core HTLS Conductor

The growing electrical energy demand and an aging electricity infrastructure underscore the need for new power overhead transmission lines. The need to refurbish the oldest lines has been initiated by the Working Group B2 of CIGRE, and high-temperature low-sag (HTLS) conductors seem to be one solution for uprating the power lines. In this paper, the electrical behavior of a new type of organic matrix composite conductor using carbon fibers and epoxy resin is especially investigated. Because of the insulating layer between the core and the aluminum wires preventing galvanic corrosion between carbon and aluminum and due to the non-negligible carbon fiber conductivity, a part of the total current flows through the carbon fibers core across this layer. Thus, a voltage drop appears between the inner and the outer layers of the insulating material, and dielectric breakdown may arise for high values of current in case of huge peak loads. The objective of this paper is to analyze the problem theoretically in an original way and to advise the way to prevent adverse effects.