What is RTD and how it works

A platinum resistance temperature detector (RTD) is a device with a typical resistance of 100 Ω at 0 °C. It consists of a thin film of platinum on a plastic film. Its resistance varies with temperature and it can typically measure temperatures up to 850 °C. Passing current through an RTD generates a voltage across the RTD. By measuring this voltage, you can determine its resistance and, thus, its temperature. The relationship between resistance and temperature is relatively linear