Thermocouple cable definitions:
Thermocouple Extension Cables:
Away from the hot junction, cables are required to carry the EMF to the instrument. The conductors need to be of the same materials to match the thermocouple but accurate over a more limited range of temperature. Extension cables are therefore more usually used to connect a number of thermocouples to a number of instruments, within a panel or junction box. Consequentially it is common for extension cables to be of multipair construction.
Thermocouple Compensating cables:
As the conductors used within some thermocouples are very expensive when compared with copper conductors, the expense of interconnecting between the thermocouple and the measuring instrument can be prohibitive, particularly when outside of the junction areas where high accuracy over the wide temperature range of the thermocouple is not required. In this area compensating cables can be used, whose conductors have similar EMF values as the thermocouple but over a limited temperature range. The constructions are therefore usually similar to extension cables.
Thermocouple Cable Types:
KX (NiCr/NiAl) Extension cable:
Possibly the most common type, the KX extension cable is made from the same elements as its Type K thermocouple. There is also a compensation cable available for this type (KCB).
TX (Cu/CuNi) Extension cable:
Made from the same elements as the Type T thermocouple that it is used with. It should be noted that there is no compensating cable available for Type T, however the extension cable is relatively inexpensive.
JX (Fe/CuNi) Extension cable:
As with the TX extension cable, there is no compensating cable available for Type J, however the extension cable is also relatively inexpensive.
NX (NiCrSi/NiSi) Extension cable:
Although there is a compensating cable available for Type N Thermocouples, it is not commonly available.
EX (NiCr/CuNi) Extension cable:
As with Type T and Type J, there is no compensating cable available for Type E.
KCB (Cu/CuNi) Compensating cable:
The compensating cable for use with a Type K thermocouple and a KX extension cable, a KCB should only be used when the temperature surrounding of the interconnection point between the cable and sensor is below 100oC.
Thermocouple Cable Listing:
Type KX Twisted Screened Extension Cables
Type KCB Twisted Screened Compensating Cables
Type JX Twisted Screened Extension Cables
Type TX Twisted Screened Extension Cables
Type NX Twisted Screened Extension Cables
Type KX Twisted Screened Armoured Extension Cables
Type KCB Twisted Screened Armoured Compensating Cables
Type JX Twisted Screened Armoured Extension Cables
Type TX Twisted Screened Armoured Extension Cables
Type NX Twisted Screened Armoured Extension Cables
Colour codings:
IEC 584-1Colour Coding
ANSI 96.1 Colour Coding
BS1843 Colour Coding
DIN 47310 Colour Coding
JIS C1610-1981 Colour Coding
NFC42-342 Colour Coding
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