Study on Inhomogeneity of Thermocouples

Abstract

In this paper, a study for a general theory of inhomogeneity errors of thermocouples, and its application to hysteresis errors of Pt versus Pt-Rh 10% thermocouples, ase mentioned. In general, the inhomogeneity error of thermocouples can be calculated easily with the aid of Fourier transform, if the variation of the thermoelectric power caused by inhomogeneity is represented by a simple function of the temperature, and if the temperature gradient used for the measurement of inhomogeneity is represented by a particular function, for instance by exponential curve. This theory is applied to the hysteresis errors of Pt versus Pt-Ph 10% thermocouples at the silver point, and the errors are estimated by calculation with the accuracy of the order of 0.5μV.