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Calibrating K-type thermocouples

Hello, 

 

I've been trying to use k-type thermocouples to measure thermal cycles in welds, but it seems that the temperature readings are significantly lower than the actual temperature (30-50 degrees C). I'm using an NI 9213 module with the DAQmx block. Is there a way to calibrate the thermocouples, and if so, how? I've attached screen shots of the block diagram. 

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Well, the TC will report the temperature he feels, that migth or migth not be the temperature of interest 🙂

30 deg offset could be a false cold junction (CJ) compensation.

If you shortcut the TC input with a short wire , you should read the CJ temperature.

A calibration is just a comparison of your setpoint (temp) and the readout.

Depending on the number of calibration points you have, you can do a compensation of the read value.

like: one point: offset from cal and use the slope of the TC standard

two and more points allow a polynominal correction.

 

 

 

 

Greetings from Germany
Henrik

LV since v3.1

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