Temperature sensors of group 203 category 2 are designed for measuring the surface temperature of solid bodies in various industries. They have small dimensions, improved thermal inertia characteristics, and do not require complex installation work when mounted on site. Temperature is the most commonly measured parameter, and overheating is one of the most negative factors in equipment operation. Therefore, there are many ways and places to use temperature sensors. The operating principle of resistance temperature detectors is based on the change in electrical resistance of conductors and semiconductors depending on temperature. The material from which such a sensor is made must have a high temperature coefficient of resistance, preferably a linear dependence of resistance on temperature, good reproducibility of properties, and inertness to environmental influences. Platinum best meets these requirements; copper somewhat less so. Thermocouples are exclusively differential temperature sensors. They generate an electrical signal proportional to the temperature difference between two different points. Therefore, the junction (weld) used to measure the required temperature is called the "hot" junction, and the other junction (which is unavoidable) is called the "cold" junction. Classification of 203 REGMIK temperature sensors by type of measuring (sensitive) element Resistance temperature detectors (thermometers) — TSM, TSP; Thermoelectric converters (thermocouples) — TXA, TXK, TZHK; Semiconductor converters — TP. Main technical characteristics of 203 temperature sensors: Sensing element connection scheme - two-, three-, four-wire; By type of sensing element divided into: Resistance temperature detectors (RTD, thermometer, temperature sensors) (50M, 100M, 50P, 100P, Pt100, Pt500, Pt1000, Pt2000, Pt10000); Thermoelectric converters (thermocouples, temperature sensors) (TXA (K), TXK (L)); Semiconductors (DS18B20); Protection rating against dust and water - IP54; Construction of temperature sensors – non-dismantlable; Insulation resistance - not less than 100 MOhm; Accuracy classes - A, B, C (for RTD), 1, 2 (for thermocouples).