Solving the Corrosion Problems on Armour Clamps on 110 kV Single-core Submarine Cables

摘要

After laying single-core XLPE cables between Peljesac and the island of Korcula we have become aware of chemical processes and induced currents occurring in the armour of flat laid cables. To achieve vector reduction of currents through the armour on the places where the cables leave the flat formation and transform into a trefoil formation, the rings that are the clamps have been installed to equalize the armour potential because conductors interconnect them. However, the original design of the clamps has not taken into account a combination of different materials present in seawater. Formation of a galvanic cell caused corrosion of the cable armour, which was accelerated by the current of the submarine cable armour. Since on some places the cable armour was completely damaged in the length more than 1 metre, the same type of clamps could no longer be used i.e. installed. In cooperation with the submarine cable producer, the clamp design has been modified by making clamps from the same kind of materials. The first new clamps were installed some two years ago so this paper reviews first experiences related thereto.