Senior Project Engineer Jerry Willis visited Sweden recently on a special mission to retrieve spare lengths of our subsea cables, Normandie 2 and GJ1, from original manufacturers ABB in Karlskrona where they have been stored since the cables were installed in 2000.
The giant turntable is prepared to receive one of the storage pans
The move is part of a new, groundbreaking subsea cable repair solution we have developed alongside Guernsey Electricity, as partners in the Channel Islands Electricity Grid (CIEG), with Dutch installation specialist Visser and Smit Marine Contracting (VSMC).
One of the 40-tonne pans is lifted into position to be lowered on to the turntable below
The £2million Power Cable Maintenance Agreement (PCMA) is causing quite a stir in the industry as it is one of the first of its kind. It is the culmination of a number of years' work during which the CIEG has developed an entire subsea cable repair system, comprising contracts, vessels, fixtures, spare cables and storage facilities.
It includes the manufacture of cable pans to store spare lengths of Jersey's 90MW interconnector to France (1,400m), Normandie 2, and the 55MW Jersey-Guernsey link, GJ1 (1700m). There is also provision of a turntable, loading arm and lifting frame to facilitate handling of the pans and cables.
The contract with VSMC includes agreed response times and rates for a number of scenarios following a fault or damage to a subsea cable. The equipment and cables will be stored by VSMC in Dordrecht, Holland, allowing easy access and rapid mobilisation in the event they are required.
Last month the two pans weighing 40 tonnes each and measuring 17 metres in diameter set sail by barge from Holland (above), to Karlskrona, Sweden, to collect the spare cable lengths from ABB.
The first spare cable is hauled up in Sweden ready for transfer to the pan on the barge
Jerry, who was the Company's representative on the repair of the faulted GJ1 circuit last year, travelled to Sweden to monitor the cables' transfer from ABB's factory to the VSMC barge ready for the journey to Holland.
The cable is pulled from the dockside up on to the arm (above) which transfers it to the pan (below)
He said: 'When subsea cables are manufactured, we ensure there is always a sufficient length left over from the installation to allow for repairs. Until now our repair cables have been stored with ABB at in Sweden. However, Karlskrona is
'snow bound' for much of the winter, making access to these cables difficult.
'Our contract with VSMC is not only for the design and build of the pans and cable storage, it covers the provision of the barges and vessels necessary to carry out future repairs so we know up front what the costs would be. The storage site in Dordrecht is also closer to the Channel Islands and more accessible. This accessibility, coupled with having the cable already in the pan which can be lifted directly on to a turntable and barge means it can be moved to a fault site much faster and more cost effectively.
CEO Chris Ambler said: 'This solution is creating considerable interest in our industry due to the explosion in growth of submarine cables and the high cost of their repairs. It is another example of our close working partnership with Guernsey Electricity which benefits both islands. It also represents part our multi-million pound on-going investment programme in our transmission network to secure low carbon electricity supplies for Jersey long into the future.'
We and the CIEG intend to store spare lengths of any future submarine cables with VSMC in the same way. This includes Jersey's third interconnector to France, the 35km 100MW Normandie 3 circuit, currently being manufactured by Prysmian Group in Naples and due for commissioning early in 2015, a new Normandie 1 cable to replace the first interconnector that failed last June and an additional Jersey-Guernsey link, GJ2.