Nexans Norway AS and Prysmian Cavi è Sistemi Energia SrL, won as a consortium a contract with Red Electrica de España, owner and major operator of the spanish power and transmission grid, as part of the COMETA (Conexión Mediterranea de Transporte de Alta tensión) project. The consortium was awarded the manufacture, transportation and installation of a high voltage 250kV DV submarine cable power link between the Spanish mainaland and the Balearic Islands.

This new link is the first HVDC submarine connection in Spain and is being fed by Spain's transmission grid, providing approcimately 25 per cent of the electricity consumed on the islands. It connects the power conversion station at Sagunto, in the Spanish peninsula, with Santa Ponça, in the Majorca Island. Also, due to the link's design, other Balearic Islands are able to be supplied through secondary 132kV and 33kV links, including Majorca-Minorca and Majorca-Ibiza-Formentera links.

As a fact, once this inteconnection was completed, it was the longest single piece of cable ever installed at that time and the second deepest in the world reaching 1,485m under water.

Assodivers had been contracted for the protection of the Sagunto-Santa Ponça interconnection in the route areas which have been characterised as hard soil. The cable protection services were succeded using rock-cutting technique and utilizing 'AssoTrencher IV' trenching vehicle, equipped with a trenching wheel and an ejector and operated from the deck of the support vessel 'Argo I'. 

Post-burial survey of the protected cable lengths was carried out using our ROV 'Argus Rover MkIII' equipped with a 'TSS-440' passive cable tracking system.

Cable sections remaining unburied, following the operation of 'AssoTrencher IV', were protected by cement mattress installation using 'AssoMat I' specialist tool attached to 'Argo I' A-frame.

Project Specifications

Cometa

Year:
2011
Contractor:
Prysmian Cavi è Sistemi Energia SrL
Cable Type:
Power 2x250kV HVDC & 1MR cable & 1FO bundled
Cable Weight:
Power: 29kg/m MR: 29kg/m FO: 3.4kg/m
Cable Diameter:
Power: 88mm MR: 84mm FO: 12mm
Service Provided:
Offshore Protection
Owner:
Red Electrica de España
Trenching Length & Cover Depth:
37,026m @ 1m & 0.5m
Alternative Protection:
Mattresses: 1,925m
Location:
Balearic Sea, Spain
Max Water Depth:
124m