Thermocouple extension and compensating cables

Cable-uni’s Thermocouple Compensating & extension cables products comply with International Standards, including standards IEC 60584-3, British standards BS4937, German standard DIN 43710, and US standard ANSI MC 96.1. Cable-uni offers a full line of thermocouple cable & wire with standard limits of error & special limits of error. Thermocouple alloy wires are available in solid or stranded configurations. We offer a wide variety of insulating, shielding, and jacketing options for our single-pair thermocouple wire & our multipair thermocouple extension cables.

What is the application of extension and compensating cables?

The value of the electromotive force (EMF) produced by the thermocouple is determined by the difference between the measuring temperature and the so-called free ends of the thermocouple which are mounted in the connection head. As the connection head is usually relatively close to the measuring point, it is frequently exposed to temperature fluctuations. For this reason, a connection cable with the same thermoelectric properties as the thermocouple is used between the thermocouple and the cold junction. This link-up provides the compensating/extension cable.

Code	+ve Leg	-ve Leg	EMF at 100° C in milli volt ref. Jn. at 0° C	Recommended working temp. in Celsius	Remarks
K	Chromel (Alloy of Chromium & Nickel)	Alumel (Alloy of Aluminium & Nickel)	4.09	0°C to 1100° C	Most Commonly used
T	Copper	Contrantan (Alloy of Copper & Nickel)	4.28	-185 C to 300° C	For low temp. & cryogenic applications
J	Iron	Constantan	5.27	20° C to 700° C	Used in reducing Atmosphere
E	Chromel	Constantan	6.32	0° C to 800° C	Highest EMF output
R	Platinum + 13% Rhodium	Platinum	0.647	0° C to 1600° C	Very high temp. measurements
S	Platinum + 10% Rhodium	Platinum	0.645	0° C to 1500° C	Very high temp. measurements
B	Platinum + 30% Rhodium	Platinum + 6% Rhodium	0.033	100° C to 1500° C	Mainly used in glass industry

What is the material difference between a thermocouple extension cable and a thermocouple compensation cable?

We differentiate between thermocouple cable and compensating cable. Cables made of original materials are called extension or thermocouple cables, whereas conductor materials made of substitutes are known as compensating cables.

Compensating cables

The compensating wires and strands are composed of alloys that do not have to be identical to the corresponding thermocouple. Substitute material means that the thermo-electric characteristics in the allowed temperature range (usually 0 up to +200 °C) for the compensating cable must be the same as those of the corresponding thermocouple. They are identified with the letter ”C“ adapted to DIN IEC 584. The ”C” appears behind the code letter identifying the thermocouple, for example,” KC”.

Thermocouple Extension Cables

Extension cables are made of conductors with identical nominal structures to the corresponding thermocouple. They are identified with the letter ”X” adapted to DIN IEC 584, which appears behind the code letter identifying the thermocouple, for example,” JX”. They are normally tested within a temperature range of 0 up to +200°C.

Thermocouple Cables

Thermocouple cables consist of the same element material as the thermocouple and are tested for the same temperatures. These special cables are manufactured on customer request. PVC, fiberglass, and tex-insulated or sheathed compensating and extension cables are not suitable for outdoor use. Exception: PVC-sheathed solid conductors can be used for underground laying.

Cable-uni offers Thermocouple Compensating & extension cables products including:

Standard	Thermocouple Compensating & extension cables(Colour code and temperature range for compensating and extension cables)
IEC 60584-3	PVC insulated compensating and extension cables, up to 70°C Silicone insulated compensating and extension cables, up to +180°C Fibre-glass insulated compensating and extension cables up to +180°C/+200°C FEP insulated compensating & thermocouple extension wires up to +180°C PFA insulated extension cables up to +250°C FEP, PFA, or Silicone insulated connection cables +180℃ /+250℃ PTFE insulated, PFA sheathed unshielded/shielded thermocouple extension cables PT100, ETFE insulated, ETFE sheathed, shielded resistance measurement cables,600/1000 V AC
ANSI MC 96.1	Low Temperature Insulation Thermocouple(PVC - 105ºC \| Nylon 121ºC): Unshielded PVC Insulated Jacketed Parallel Pair Thermocouple Cable Shielded PVC Insulated and Jacketed Twisted Pair Thermocouple Cable Type EX Multi-pair Overall Shield PVC Insulated and Jacketed Thermocouple Extension Cable Type SX Multi-pair Individual and Overall Shield PVC Insulated and Jacketed Thermocouple Extension Cable Unshielded Nylon Insulated and Jacketed Parallel Pair Thermocouple Cable High Temperature Insulation Thermocouple(FEP - 200ºC \| PTFE - 260ºC \| PFA - 260ºC): Shielded-PFA Insulated and Jacketed Twisted Pair Thermocouple Cable Unshielded PFA Insulated and Jacketed Parallel Pair Thermocouple Cable Twisted Pair Thermocouple Cable Shielded PFA Insulated and Jacketed Unshielded PTFE Tape Insulated and Jacketed Parallel Pair Thermocouple Cable Shielded-FEP Insulated and Jacketed Twisted Pair Thermocouple Cable Unshielded FEP Insulated and Jacketed Parallel Pair Thermocouple Cable Unshielded-FEP Insulated and Unjacketed Twisted Pair Thermocouple Cable
BS4937	Armoured/Non-Armoured Compensating & Thermocouple Cable
CSA C22.2	CSA ACIC Armoured Thermocouple Extension \| Pairs (300V) CSA Unarmoured Tray Thermocouple Extension \| Pairs (300V)