High-voltage power cable for Northwind offshore wind farm

About the project

In 2012, Nexans was awarded a contract to supply high-voltage power cable for Northwind offshore wind farm. 57 km of 245 kV subsea cable are now connecting Belwind Phase 2 to Northwind and then on to landfall at Zeebrugge, Belgium.

The Northwind wind farm comprise of 72 wind turbines, summing up to a total of 216 MW installed capacity. The power is delivered to the Belgian electricity network at the ELIA HV connection station in Zeebrugge. The 14 km section of 245 kV cable connecting Belwind Phase 2 to Northwind will consist of three copper cores, each with a cross-section of 400 mm2.

Nexans' soultion

In addition to the design, type-testing and supply of the XLPE subsea cables, Nexans also supplied mechanical and electrical accessories. This included the onshore transition joints to connect the subsea cables to the land cables, the accessories for the two platforms, comprising hang-off and GIS (gas insulated switchgear) terminations, and four repair joints.

The majority of the 43 km, 245 kV connection from Northwind to Zeebrugge comprised of three 1000 mm2 copper cores. However, there was a length of the route where the cable had to traverse a sea channel subjected to regular dredging, requiring it to be buried down to 9 metres in the seabed for protection. In order to maintain the electrical performance of the cable along this channel, the copper cross-section was increased to 1200 mm2 on a 4 km section. This section of cable had an outer diameter of 265 mm and had a weight of 130 kg per meter.