RTD (Resistance Temperature Detector), Resistance thermometers are a temperature sensor in the logic of changing the resistance value of a conductive wire depending on the temperature.

Resistance thermometers, which were found and started to be used after thermocouple in temperature measurements, are very widely used in industry and laboratories.

The wound-up resistance is immersed into the desired medium, the temperature of which is calculated, a constant current is passed through it. With the change of temperature, the resistance value of the wound resistance changes, and a voltage that changes with a constant current passing through it is obtained.