A resistance temperature detector (RTD) is a type of temperature sensor. As the name suggests, it is a Resistive (R) Temperature (T) Detector (D) that utilizes the property of metals whose electrical resistance changes with temperature.
RTDs are commonly used for high-precision measurements and have the following characteristics:
- The relationship between resistance and temperature is linear and highly reproducible.
- High accuracy in low-temperature measurements.
Currently, platinum (Pt100Ω) is often used as the sensing material because of its stable characteristics and easy availability. This is specified in JIS C1604.
The standard, C1604, has been revised three times: in 1981, in 1989 (to correct discrepancies with IEC standards), and in 1997 (an update to JIS 1989).
Most commonly used RTDs (Pt100Ω) comply with the C1604-1997 standard. (The C1604-1981 standard is referred to as “old JIS” or “JPt” and is distinguished separately.)
As for lead wire configuration, the three-wire type (A, B, B) is most commonly used. However, two-wire (A, B) and four-wire (A, A, B, B) configurations are also available.
