Accuracy of thermocouple temperature meters
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What factors affect the accuracy of thermocouple temperature meters? For example, does the temperature measured by the thermocouple be more accurate during the day or at night?
The accuracy of thermocouple measurements is not affected by day or night; generally, only the compensation wires and compensation resistors can influence the measurement accuracy!
Digital display instruments all have cold-junction compensation; as long as thermocouple compensation wires are used, there will be no errors. Dynamic headphones will have errors.
As a temperature sensing element, a thermocouple can be used to measure the temperature of gases, liquids, and solids as long as it is paired with a display instrument; therefore, it is one of the most widely used temperature sensing elements. However, the relationship between its output thermoelectric potential and temperature is nonlinear, with a fairly high degree of nonlinearity. As per the working principle of thermocouples, the thermoelectric potential generated by them is related to the temperature difference across the thermocouple. Moreover, the temperature-thermoelectric potential calibration table is established with a reference temperature of 0°C. Therefore, in practical use, the accuracy of linearization processing of the thermocouple and the compensation for the cold junction temperature are two key factors that affect the accuracy of its measurements.
Now, the card devices will automatically perform compensation; all that’s needed is to select the appropriate compensation wire, and that’s it. It’s best to connect the compensation wire directly to the terminal pins of the card device
The thermoelectric potential of a thermocouple is related to the temperature difference between its hot and cold ends; therefore, changes in the temperature of the cold end affect the measurement accuracy
Using a cold-end temperature compensation wire generally eliminates this issue. It doesn’t really matter whether it’s day or night; what causes interference are high currents or frequencies, vibrations, etc.
I’ve learned it, thank you all. I would like to ask again: will a difference in the ambient temperature of the cold end and that of the end of the compensation wire affect the measured temperature?
Is there any good way to solve this problem if it occurs?