Extension cables
Extension cables are manufactured as stranded conductors and as solid conductors with various insulations and armouring. According to IEC / EN 60584-3, the extension cable is designated with the letter "X", which is placed after the code letter of the thermocouple (e.g. "KX"). The electrical conductors of the extension cables (i.e. the flexible strands or the solid wires) consist of materials which nominally have the same chemical composition as the original materials of the associated thermocouple according to IEC / EN 60584-1.
The extension cable is available for thermocouple types K, N, J, T and E (all according to IEC / EN 60584-1).
The following table 1 gives an overview of the materials and accuracy class of extension cables with the corresponding thermocouples.
Type | Accuracy class | Application temperature range | Temperature of the measuring point | |
1 | 2 | |||
JX | ±85 µV (± 1.5 °C) | ±140 µV (±2.5 °C) | -25 °C to + 200 °C | 500 °C |
TX | ±30 µV (± 0.5 °C) | ±60 µV (± 1.0 °C) | -25 °C to + 100 °C | 300 °C |
EX | ±120 µV (± 1.5 °C) | ±200 µV (± 2.5 °C) | -25 °C to + 200 °C | 500 °C |
KX | ±60 µV (± 1.5 °C) | ±100 µV (± 2.5 °C) | -25 °C to + 200 °C | 900 °C |
NX | ±60 µV (± 1.5 °C) | ±100 µV (± 2.5 °C) | -25 °C to + 200 °C | 900 °C |
KCA |
| ±100 µV (± 2.5 °C) | -0 °C to + 150 °C | 900 °C |
KCB |
| ±100 µV (± 2.5 °C) | -0 °C to + 100 °C | 900 °C |
NC |
| ±100 µV (± 2.5 °C) | -0 °C to + 150 °C | 900 °C |
RCA |
| ±30 µV (± 2.5 °C) | -0 °C to + 100 °C | 1000 °C |
RCB |
| ±60 µV (± 5.0 °C) | -0 °C to + 200 °C | 1000 °C |
SCA |
| ±30 µV (± 2.5 °C) | -0 °C to + 100 °C | 1000 °C |
SCB |
| ±60 µV (± 5.0 °C) | -0 °C to + 200 °C | 1000 °C |
Source: Data from IEC / EN 60584-3:2008 Chapter 5.3
Comments:
The range of application can be reduced depending on the insulation material. For type B thermocouples, one cable consisting of two copper cables may be used. The expected maximum additional deviation within the application temperature range from 0 °C to + 100 °C is 40 µV. The corresponding temperature value is 3.5 °C, if the measuring point of the thermocouple has a temperature of 1400 °C.
The extension cables shown in the list are available in the colour codes according to IEC / EN 60584-3. The cables can also be supplied in other colours on request.
Type of thermocouple | Colour code of positive conductor and sheath | Colour code of the negative conductor |
J | Black | White |
T | Brown | White |
E | Violet | White |
K | Green | White |
N | Pink | White |
R | Orange | White |
S | Orange | White |
B | Grey | White |
Source: Data from IEC / EN 60584-3:2008 Chapter 5.3