A large amount of measurement data will be generated during the thermocouple calibration process. Correctly processing these data and evaluating the uncertainty is a key step in obtaining accurate calibration results.First, in terms of data processing, it is necessary to sort out the measurement data of the thermocouple and the standard thermometer at each calibration temperature point. Usually, the method of taking the average value of multiple measurements is used to reduce the influence of random errors. For example, 5 - 10 measurements are made at each temperature point, and then the arithmetic average value of these measurement values is calculated as the measurement result at that temperature point. At the same time, an outlier test needs to be carried out on the measurement data. If there are data points that deviate significantly from other measurement values, the cause of their generation needs to be further analyzed, such as whether there is a sudden failure of the measuring instrument or environmental interference. If it is determined to be an outlier, it should be removed and the average value should be recalculated.
For uncertainty evaluation, it reflects the reliability of the measurement result. Uncertainty is mainly composed of several components, including the uncertainty introduced by measurement repeatability, the uncertainty of the standard thermometer, the uncertainty introduced by the temperature stability of the calibration equipment, etc. The uncertainty introduced by measurement repeatability can be calculated by statistical methods. For example, the Bessel formula is used to calculate the standard deviation of multiple measurement data, which is used as the uncertainty component introduced by measurement repeatability. The uncertainty of the standard thermometer is usually given by its calibration certificate. The uncertainty introduced by the temperature stability of the calibration equipment needs to be evaluated according to the technical parameters of the equipment and the temperature fluctuation situation during the actual measurement process. Finally, each uncertainty component is combined in a certain way to obtain the total measurement uncertainty. Only when an accurate measurement result is given and a reasonable uncertainty evaluation is attached can the accuracy of thermocouple calibration be completely reflected.
