The Pt100 sensor, like any resistance thermometer, uses the effect that metals change their resistance when the temperature changes. The measuring range of Pt100 sensors varies depending on the instrument, sensor element and accuracy class. At a temperature of 0 °C, a Pt100 measuring resistor has a nominal resistance of 100 Ω (ohm). As the temperature falls or rises, the electrical resistance also changes. This change occurs in line with a characteristic curve defined by international standards. Thus, the temperature can be determined very-precisely on the basis of the measured resistance.