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Posted

There is a discrepancy of readings from USB-TEMP and a digital multi-meter when connecting USB-TEMP to NTC.

The discrepancy is about 10 to 20% between USB-TEMP & digital multi-meter (ohm readings). The discrepancy getting higher as the temperature increases.

We have keyed in the correct Steinhart-Hart Coefficients in the Instacal setup.

image.png.1c2a3614adb93f40f5903f02af336024.png

The setup is No Scale (as we want the measured value to be RESISTANCE.)

image.png.b6077c44030ffb5ee041ee6c0aaef00e.png

We are using 2-wire NTC, single-sensor configuration.

image.png.ac51ae7ab2b1184edfbe341f69c42e37.png

Can you please advise what is the possible cause of discrepancy in readings from InstaCal  and ohmmeter ?

Thank you.

 

 

3 answers to this question

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  • 0
Posted

Connecting anything to the input terminals while the device runs can alter the measurement, especially if it's an ohm meter. Can you share why you're doing this?

  • 0
Posted

Instead of probing the input terminals, they could use a resistor to simulate a temperature. Take, for instance, this thermistor profile. For this 10k thermistor, a 270 ohm resistance should return a temperature close to 134 degrees C. Use a 1% or 0.1% resistor for best results. 

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