Thermocouple extension and compensating cables are designed for interconnection between thermocouple probes and control instrumentation. They are generally available in the following types:
Type (1) Unarmoured cables with conductors insulated with PVC and twisted together in pairs, sheathed overall with PVC.
Type (2) Armoured cables with conductors insulated with PVC and twisted together in pairs, PVC bedding, Galvanised steel wire armour and sheathed overall with PVC.
All of the above types of cables can be supplied unscreened or screened (individually, collectively or both) with an Aluminium Polyster tape screen incorporating tinned copper drain wire.
The construction is similar to paired instrumentation cable but the conductor material is different. Thermocouple are used in processes to sense temperature and is connected to the pyrometers for indication and control. The thermocouple and pyrometers are electrically connected by thermocouple extension / compensating cables. The conductors used for these cables are required to have similar thermo-electric (emf) properties as that of the thermocouple used for sensing the temperature.