AiVibeResistance Temperature Detector (RTD)
A resistance temperature detector is a temperature sensor whose electrical resistance rises predictably with temperature; platinum RTDs such as the Pt100, with 100 ohms at 0 °C, are widely used for accurate industrial measurement.
An RTD element is a fine wire or thin film of metal, usually platinum, whose resistance increases almost linearly with temperature. The measuring instrument passes a small excitation current through the element and calculates temperature from the measured resistance using standard curves. IEC 60751 specifies the characteristics and tolerance classes of industrial platinum resistance thermometers, and Pt100 and Pt1000 elements are the most common types.
RTDs are used where accuracy, stability and repeatability matter, such as process temperatures in chemicals, food, pharmaceuticals and HVAC, bearing and winding temperatures in motors and generators, and laboratory and calibration work. Compared with thermocouples, they are generally more accurate and stable but cover a narrower temperature range and often respond more slowly.
Lead wire resistance adds error, so two-wire connections suit only short runs, three-wire connections compensate for matched leads and four-wire connections give the highest accuracy. Self-heating from the excitation current, thermal contact with the process and the use of thermowells affect readings. Transmitters often convert RTD signals to 4–20 mA or digital protocols, and calibration should be traceable to recognised standards.
Key points
- Resistance rises predictably with temperature
- Pt100 elements have a resistance of 100 ohms at 0 °C
- IEC 60751 specifies platinum RTD characteristics and tolerance classes
- Three- and four-wire connections compensate for lead resistance
- More accurate and stable than thermocouples over a narrower range
Where AiVibe comes in
AiAmbA IoT is AiVibe's edge protocol layer: it discovers devices and normalises industrial signals, with supported protocols including Siemens S7, Mitsubishi MC, Delta Modbus, OPC UA and MQTT, and driver availability confirmed per installation. Writes to machines are deny-by-default.