Technology

Cable colours for compensating cables

Different colours are used for the corresponding compensating cables for the different thermocouple types. Although there is an international European standard (DIN IEC 485), many cables are still manufactured and used according to national standards. The following table summarises the most important ones.

National standards (pdf approx. 24kByte)



Polynomials for temperature calculation according to the ITS90

Polynomials up to the 14th order are used to calculate the temperature from a measured thermoelectric voltage at a reference junction temperature of 0°C. These polynomials are shown in the following table. These polynomials are shown in the following table. The polynomials can also be obtained from us as a text file. This means that they can be used in your own programmes without errors.

Polynomials (pdf approx. 16kByte)

Quality classes for Pt resistors:

   
Class            

Scope of validity
Limit deviation


Coiled resistor

         

Resistance layer

          
AA

−50 … +250 °C

 

0 … +150 °C
0,1 °C + 0,0017 ∙ |t|
A

−100 … +450 °C

 

−30 … +300 °C
0,15 °C + 0,002 ∙ |t|
B

−196 … +600 °C

 

−50 … +500 °C
0,3 °C + 0,005 ∙ |t|
C

−196 … +600 °C

 

−50 … +600 °C
0,6 °C + 0,01 ∙ |t|

Example for class AA (= 1/3 DIN)

Given: Temperature sensor with class AA sensor, ambient temperature 200°C

Formula: tg = 0,1 °C + 0,0017 · |t|

Calculation: 0,1°C + (200°C x 0,0017) = 0,1°C + 0,34°C = 0,44°C

  • At 200°C, deviations in the measured value of up to ± 0.44°C are permissible.