Norwegian power company BKK Nett is soon to be the operator of a record-breaking subsea power link. Nexans has just completed a project to install the world's longest and deepest 420 kV XLPE (cross-linked polyethylene) insulated submarine cable system. In a turnkey project worth around €75 m to reinforce the grid in western Norway, Nexans has delivered 90 km of 420 kV AC XLPE cable.
The new power link, comprising three single core cables in parallel, runs between Mongstad and Kollsnes, crossing two fjords, Hjeltefjorden and Lurefjorden. At its deepest point, the cables were installed at 390 m, making this both the world's deepest 420 kV XLPE system, and longest at this depth, with a length of 22 km. Its total length is around 30 km. On land, overhead lines will carry the power. However, the major part of the route crosses the two fjords.
The cable system for the subsea route was manufactured, delivered and installed by Nexans. The cables were laid by Nexans' cable laying vessel, C/S Nexans Skagerrak. In the near-shore areas, the cables were mainly protected with HDPE pipes, outer shells or trenched by water jetting.
The cables were manufactured at Nexans' facility in Halden, Norway, and cable laying was completed in May. The next stage is to complete termination works on shore, ready for handover testing in the autumn this year.
BKK is building the new connection to reinforce the power grid in the west of the country. The new power line is essential to ensure security of supply for the forecast growth in consumption by residents, businesses and industrial consumers in the Bergen region, which is an important growth area. It will also provide additional capacity for the grid connection of new generation resources.
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