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I am measuring a thermocouple by AD7124-4 application.

Question asked by hahmin on Mar 19, 2018
Latest reply on Jun 10, 2018 by hahmin

Hello.

 

I used to get help before in this site.

I was really good. and there was no problem.

but another problem is occurred.

 

I have a problem when I calculate a temperature from a K-type thermocouple data.

To get the temperature by thermocouple, I got two temperature a "cold" junction and "hot" junction temperature for the thermocouple as follow the 7124 datasheet.

 

 

my calculation is  as follows:

    total_temperature = Hot_junction + Cold_juntion

 

but when I heat the "cold" junction, the total_temperature is changed.

My developed controller has the cold-junction inside. So when i supply power, the controller is heated

and total_temperature value is changed.

 

My question is :

   1) is the calculation right?

   2) Does the thermocouple has the feature that the total_temperature always get effected by the "cold" junction           temperature?

    3) If number 2) is right, how can i reduce effect of the "cold" junction?

    4) Does Other controller by thermocouple has these feature?

 

 

thank you for reading despite my weak English skills.

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