An RTD (Resistance Temperature Detector) sensor measures temperature by monitoring the electrical resistance of a pure metal element, typically platinum, which increases predictably with temperature. RTD sensors provide high accuracy across -200°C to 600°C ranges, with repeatability within ±0.1°C. They offer superior long-term stability compared to thermocouples and require no cold junction compensation.
Technical Details
Platinum RTDs follow the Callendar-Van Dusen equation, delivering ±0.15% accuracy per IEC 60751 Class A standards. Pt100 (100 ohms at 0°C) and Pt1000 configurations serve different application ranges. Four-wire connections eliminate lead resistance errors. Response times range from 5-30 seconds depending on probe design and thermal coupling.
HVAC Applications
RTD sensors install permanently in furnace supply air ducts, boiler return lines, and heat pump compressor discharge lines. They integrate into building automation systems and data loggers for continuous temperature monitoring, system control algorithms, and efficiency reporting across commercial HVAC systems.
Practical Significance
RTDs provide reliable long-term measurements for system performance verification and predictive maintenance programs. Their superior accuracy supports energy management initiatives and equipment commissioning without frequent recalibration requirements.