LS Cable & System and Jan De Nul Group announce the completion of the first lot of submarine power cables for TenneT’s offshore projects Hollandse Kust noord and west Alpha in the Netherlands. Jan De Nul’s cable laying vessel Isaac Newton will load the 220 kV AC cables from LS Cable’s factory in Donghae, South Korea, and transport them to the project for installation in April 2022.

This first lot consists of the complete cables for Hollandse Kust (noord) and the nearshore section for the Hollandse Kust (west Alpha). In total, this is more than 90 km of cables, weighing 7,160 tonnes and having very large cross sections resulting in an overall cable diameter of more than 25 cm. Jan De Nul Group and LS Cable & System are jointly responsible for the design, supply, installation, protection and testing of the 210 km of submarine power cables for HKn and HKwA of TenneT. Delivery of the HKn project is foreseen by the end of 2022. The HKwA project is planned to be finished by the end of 2023. Both windfarms have an installed capacity of 700 MW. This means they will generate together the amount of energy that is used yearly by approx. 1.4 million Dutch households.

The cable laying vessel Isaac Newton will install the cables on the seabed. In the nearshore area, the in-house developed tracked vertical injector Moonfish will bury the cables up to 8 m below the seabed level. The burial offshore is taken care of by the trencher UTV1200, supported by the multipurpose vessel Adhémar de Saint-Venant. Jan De Nul will also install multiple cable protection systems and rock berms at the cable crossings along the route.

Jan De Nul’s scope includes the transport and installation of the submarine power cables. LS Cable is responsible for the design, manufacturing, termination and testing of the submarine power cables, as well as for the 10.5 km of land cables and approximately 1 km of platform cables. The land and platform cables were already successfully manufactured and transported to the project site earlier in 2021.

About the submarine cables

Nominal voltage of 220 kV AC

Overall cable diameter of more than 25 cm

Minimal amount of factory joints

In-house developed joints and terminations

Integrated 144 fibres using 3 loose tubes stainless steel FO cables

About the Hollandse Kust (noord) and (west Alpha) project

With the Hollandse Kust (north) and (west Alpha) projects, TenneT takes care of the connection of the wind farms in the North Sea to the national electricity grid (Grid at Sea), and of the wind farms to be constructed in the North Sea to the national electricity grid (Net op Zee.

TenneT is constructing two offshore platforms, one for Hollandse Kust (noord) and one for Hollandse Kust (west Alpha). These platforms gather the wind energy generated by the corresponding wind farms and transform this energy from a voltage of 66kV to 220kV.

To transport the energy to the mainland, two submarine power cable systems per platform run from the offshore platform to the onshore grid, meaning in total four cable systems. They arrive on land just north of Wijk aan Zee, in the municipality of Heemskerk.

A new onshore transformer station is being built to transform the energy further to a voltage of 380kV.

The construction of the Grid at Sea and the wind farms is being carried out on behalf of the Dutch Ministry of Economic Affairs and Climate.

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