Choice of cable for subsea power links

Summary form only given. Subsea cable technology has advanced to allow the manufacture of both single and three core cables for bulk power transfer between transmission systems in continuous lengths up to 100 km. The mechanical and electrical integrity of these cable systems is enhanced by the ability to manufacture the cable in long lengths, thereby removing discontinuities at jointing positions. Handling of long length cables is complex, requiring manufacturing facilities capable of insulating, sheathing, armouring, storing and off-loading the cable to be located on the same site. A 100 km continuous length of completed, armoured cable for example may weigh in excess of 8000 Tonnes. The installation of subsea cable presents many challenges in mechanical and marine engineering. The cable must withstand the significant mechanical forces which are generated during installation due to its own weight and the action of tidal currents. The installed cable is also at risk from damage by anchors, fishing activity, vessel impact, movement of the cable or seabed terrain. To protect the cable during laying or in service metallic armour wires are applied in one or two layers to the construction as part of the manufacturing process, however, additional protection can be offered by burying the cable in the seabed using a variety of jetting, ploughing or trenching techniques. The paper describes the choice of cable design which exists for subsea power links and the merits of these various designs. The manufacture and installation of long continuous lengths of subsea power cable is discussed with reference to some key installations