Function
The cable outer surrounds the core and contains materials to protect the cable and house the fibre optic cable.
Who supplies them
Commodity suppliers.
Fibre optic manufacturers: Hexatronic and Huber+Suhner.
Fibre optic jointers and systems: Aceda and CCL UK.
Key facts
For a three-core cable, the cores are surrounded by non-conductive filling and packing material made from polypropylene. Its purpose is to maintain the cable’s shape and structure. All are then bound together with tape into a single cable.
A layer of polypropylene string is applied over the assembly as bedding for the armour wires.
The armouring is usually made up of helical metal wires surrounding the cable. Three-core subsea cables usually have stainless steel wire armour and single-core cables usually have non-magnetic galvanised steel armour. The choice of armouring is important as impacts the cable’s protective, handling, and electrical properties.
Bitumen may be applied over the armouring to protect against corrosion and to provide additional adhesion.
Polypropylene yarn covers the armour, to provide resistance to abrasion and to reduce friction during laying. It is applied with a black and yellow pattern to make the cable visible during laying.
Single-core cables can be laid separated or close. Close laying gives lower losses. Separation eliminates mutual heating but means higher losses in the armour.
At least one fibre optic cable is integrated into the power cable for communications. The cable is multimodal, meaning that it can carry a wide range of data at different frequencies, typically for voice, turbine, switchgear, condition monitoring and security information. A fibre optic cable typically has 48 strands.
What’s in it
- Bitumen
- Polypropylene strings
- Steel wire