PT100 (Platinium Resistance Thermometers) can be used with high accuracy in the temperature range from -200 ° C to + 850 ° C. It is used in processes such as machines, tanks, pipes, gas and liquid media and surface measurements. The principle of temperature measurement is to measure the resistance of the platinum element. PT100, the most widely used type of resistance thermometer, has a resistance of 100 Ohms at 0 ° and 138.4 Ohms at 100 °. The relationship between temperature and resistance in PT100s is close to linear when considering a small temperature range. For example, if 0 ° C to 100 ° C is considered linear, the error at 50 ° C will be around 0.4 ° C. The most recent definition of the relationship between temperature and resistance is made with International Temperature Standards 90 (ITS-90).