Jan De Nul completes cable repair work for TenneT in German Bight


Jan De Nul Group has successfully repaired TenneT’s AC108 cable connecting the Trianel Borkum offshore substation with Tennet’s DolWin alpha converter station.

The repairs are part of the service level agreement for cable repairs that Jan De Nul Group and TenneT entered into in 2019.

TenneT engaged Jan De Nul for the repair of a cable fault located within the 500-metre zone around the DolWin alpha platform, 75 kilometres off the German coast north of the island of Borkum. This offshore platform connects three wind farms in the German North Sea to the German extra-high voltage grid, and is therefore vital for these wind farms to get the green energy ashore.

Within less than 50 days, Jan De Nul performed the specific detailed engineering, the vessel mobilisation, the replacement of the damaged cable section, as well as the burial of the new cable and joint.

For the repairs, Jan De Nul mobilised the cable-laying vessel Isaac Newton and the multi-purpose vessel Adhémar de Saint-Venant.

First, Adhémar de Saint-Venant de-buried the damaged cable section including its cable protection system, which was buried under large armour rock.

Isaac Newton loaded the spare cable and repair joint in Emden, recovered the damaged cable section offshore, and subsequently installed the new cable and joint with success. Jan De Nul’s jet-trenching vehicle PT1, installed on-board Isaac Newton, completed the repair campaign by burying the new cable section 1.5 metres below the seabed.

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