What is the RTD - Resistance Thermometer Detector?
Compared to the thermocouple, the RTD (Resistance Temperature Detector) is generally more linear and drift-free within its measuring range. However, due to their platinum content and more complex construction, they are more expensive than thermocouples. You will typically find RTDs used in applications such as pharmaceuticals, where precise temperature measurements must be made over a long time. They don’t range much above 600° C, however, so thermocouples are a better choice for high temperature “contact” applications.
Unlike the thermocouple which is self-powered, the RTD is powered by the measuring system. The RTD measures temperature via electrical resistance which changes in a highly linear fashion with respect to temperature. Although at its core an RTD is a 2-wire sensor,
the addition of one or even two more wires (3 and 4-wire hookup) provides better compensation against self-heating and lead wire resistance and is recommended. Dewesoft signal conditioners provide 2, 3, and 4 wire hook-up possibilities.
The PT100 (“PT” = platinum and “100” = 100Ω at 0°C) and PT1000 are the most popular variants of the RTD, however, we also support Pt200, Pt500, and Pt2000 sensors.