The subsea COBRAcable connecting the electricity networks in the Netherlands and Denmark, out of operation since September 2020 due to a failure, is to be back in operation today.

The 202 mile COBRAcable is a 320 kV, 700 MW HVDC submarine power cable that consists of two parallel cables, each with a 5.1″ diameter and includes fiber optic communication. It connects Eemshaven in the Netherlands and Endrup near Esbjerg, Denmark.

Jointly owned by Energinet.dk and TenneT, the cable has been built with the purpose of improving the European transmission grid and thus increasing the amount of variable wind power in the system while also improving supply reliability. 

The cable has directly connected the Dutch and Danish electricity networks since 2019 but was out of operation due to a failure in the cable since the end of September.

The repair operation has been successfully performed.

The cable was cut at the depth of 131 ft on the seabed and lifted. On both sides of the cut cable, the cable was measured 656 ft long to find the exact fault location. 

The piece of cable where the fault has been located was removed and a new piece of cable has been installed and reconnected to the cable. The cable has been successfully tested and laid back, buried 6.6 ft deep in the seabed.

The COBRAcable connection is to be back in operation on January 8, the company said in a press release.

The successful repair will re-enable the import and export of renewable electricity between Denmark and the Netherlands.  

Source: TenneT