Improper wiring selection of RTD (Resistance Temperature Detector) will severely compromise temperature measuring precision, as there are prominent performance gaps among 2-wire, 3-wire and 4-wire RTD configurations.
2-Wire RTD
Featuring the simplest construction with only two connecting leads, 2-wire RTD comes with the lowest procurement cost. However, the inherent resistance of extension cables will be included in measured resistance values and cause reading drift. It is only recommended for short wiring runs and applications with low accuracy requirements.
3-Wire RTD (Most Popular for Industrial Use)
As the industry-standard option, the extra compensating lead eliminates most measuring errors induced by lead resistance. It delivers balanced accuracy and outstanding cost performance. Widely installed on boilers, process pipelines and other general industrial equipment, its maximum effective transmission distance ranges from 50 meters to 100 meters.
4-Wire RTD (High Precision Grade)
Boasting top-tier measurement accuracy, 4-wire RTD adopts a dedicated circuit design: two wires supply constant excitation current while the other two independently detect signal voltage. This design completely rules out lead resistance interference, restricting total measurement error within ±0.2%. It is the preferred choice for laboratory precision testing, semiconductor production and other high-accuracy temperature measurement scenarios.
Quick Selection Guide
- Low-cost & short-distance measurement: Choose 2-wire RTD
- Regular industrial temperature monitoring: Choose 3-wire RTD
- High-precision demanding applications: Choose 4-wire RTD