RTD (Resistance Temperature Detector)

An RTD is a temperature sensor that measures temperature from the change in electrical resistance of a metal element, usually platinum, as it heats or cools. RTDs offer high accuracy, excellent stability, and good repeatability, making them preferred where precise temperature measurement is required.

The most common RTD, the Pt100, has a platinum element with a precisely defined resistance-versus-temperature relationship, measured using two, three, or four wire connections to compensate for lead resistance. RTDs are more accurate and stable than thermocouples but cover a narrower range and respond more slowly. They matter in industry wherever tight temperature control and traceable accuracy are essential, such as in pharmaceuticals, food processing, and laboratory-grade process measurement.