1. Materials used in various types of cables
Instrumentation cable construction is of a very complex nature. There is a vast variety of sizes and construction used by various project consultants.
Listed below are various options available within cable constructions, allowing engineers to specify cables that are best suited to the application.
Conductor
Electrolytic grade, annealed plain or tinned copper, either solid or stranded. Thermocouple cables with matched pair of thermocouple alloys.
Insulation
Depending on conductor temperature, flame retardancy, electrical characteristics, compatibility and flexibility various insulating materials such as PVC, Polyethylene, XLPE, Mica tape etc.
Identification
Identification either by colour code and /or by no. printed tapes over pairs.
Electrical Screening
Electrical screening is provided over twisted elements and /or total cable to protect fidelity of the signal.
Inner Sheath
Material such as PVC, Polyethylene, FRLS PVC, LSF are used to serve as electrical insulation as well as chemical ingress barriers.
Armour
Galvanized steel wire or strips applied spirally over inner sheath or symmetrical or asymmetrical braid depending on final use of the cable.
Outer Sheath
The choice of sheathing material depends on the application requirements such as temperature, flame retardancy, smoke and acid gas emission limitations (Halogen free), resistance to chemicals and water, flexibility, exposure to UV and hazardous environment, anti-rodent and anti-termite properties. The materials used are PVC and Polyethylene LSF.
|
