The cable between a thermocouple and the measuring instrument is part of the measurement circuit. Its conductor materials must match the thermocouple type. Check the temperature along the route and the mechanical conditions as well.
We offer thermocouple extension and compensating cables with different insulation materials and core combinations. Selection requires the thermocouple type, cable length and temperatures at the connections.
Extension cables X and compensating cables C
Extension cables such as NX, KX, EX and JX use the alloys associated with the thermocouple. Compensating cables such as KCA use substitute materials with matching thermoelectric properties over a limited temperature range. C identifies a compensating cable; a following A or B distinguishes the version where applicable.
Matching materials alone do not guarantee error-free measurement. Tolerance class, temperature range and connections must suit the measurement task too. IEC 60584-3 addresses identification and tolerances for these cables. IEC 60584-3
Insulation temperature and thermoelectric range
The insulation’s temperature resistance is different from the cable’s permitted thermoelectric range. A heat-resistant sheath does not extend the compensation range of the conductor materials.
Options can include PVC, ETFE, FEP, PFA and fibreglass. Use the limits for the actual cable rather than treating a general material value as its rating. For fibreglass, pay particular attention to the intended dry environment.
| Information | Effect on the measurement circuit |
|---|---|
| Thermocouple type | Determines the required material match |
| Cable designation and tolerance | Identifies the appropriate extension or compensating cable |
| Temperature along the route | Must suit the insulation and thermoelectric range |
| Connections and polarity | Must agree with the cable and measuring instrument |
Check the colour-code system
Read core and sheath colours against the stated identification system. IEC and ANSI use different colours. Colour alone therefore cannot reliably identify the cable.
See our thermocouple extension and compensating cable range for the available types. Include the sensor type, complete cable designation and service conditions along the route in your enquiry.