The trend of development of measuring equipment in particular measuring systems and technological processes leads to the need of measuring the temperature without dismantling the primary transducers and stopping the technological process in a very wide range and with high accuracy. The choice of methods and means of measurement depends on such factors as the value of measured temperature, necessary accuracy of measurement, conditions of measurements, and operation of the investigated object.
The hard operation conditions of temperature thermotransducers which involve their thermal cycling require special attention to the study of processes occurring in structural elements, in particular in thermometric materials. Operation impacts cause the drift of thermometric characteristics due to the influence of the few factors main of which seem to be the thermo structural stresses.
Thermocouples are the most popular sensors of temperature used in measuring praxis for temperatures in the range 600–2500 ºC, in spite of their drawbacks. The most important among them is their error, which is often too big for many cases in industry and science. The total error of thermocouples is much greater than that of their measurement channels. The main errors proper for thermocouples are as follows: 1. Considerable initial deviation of their conversion characteristic (CC) from the nominal one.