RTD stands for Resistance Temperature Detector and is often referred to as a thermal resistor. It is a sensor that measures temperature by utilizing the characteristic of the resistance value of a conductor or semiconductor changing with temperature.
Core principle
The core principle of RTD is the temperature coefficient effect of resistance: the resistance of most metal conductors increases regularly with temperature, and there is an approximately linear correspondence between their resistance value and temperature. By measuring the resistance value, the corresponding temperature can be converted.
Key features
High measurement accuracy
Compared to thermocouples and thermistors (NTC/PTC), RTDs have higher temperature measurement accuracy, especially in the medium and low temperature range (-200℃~650℃), with errors controlled within ± 0.1℃, making them suitable for scenarios with strict temperature accuracy requirements.
Strong stability
During long-term use, the resistance drift of RTD is small, the performance degradation is slow, stable measurement data can be maintained, and the service life is long.
Good linearity
Within the effective temperature measurement range, the linear relationship between resistance value and temperature is significant, making data calibration and signal processing easier.
Slow response speed
Due to the influence of thermal conductivity and thermal capacity of metal materials, RTDs have a slower response speed to temperature changes than thermistors and are relatively more expensive.
Common types
According to different materials, RTDs are mainly divided into the following two categories:
Platinum Thermistor (Pt Series)
This is the most commonly used type of RTD, with Pt100 (resistance value of 100Ω at 0℃) and Pt1000 (resistance value of 1000Ω at 0℃) being the most widely used. Platinum has good chemical stability, a wide temperature measurement range (-200℃~850℃), and extremely high accuracy. It is commonly used in industrial precision temperature measurement, medical equipment, laboratory instruments, and other scenarios.
Copper Thermistor (Cu Series)
The common models are Cu50 (with a resistance value of 50Ω at 0℃) and Cu100, which have low cost and good linearity, but have a narrow temperature measurement range (-50℃~150℃) and are easily corroded. They are mostly used in low-temperature environments with low precision requirements, such as temperature detection for household appliances such as air conditioners and refrigerators.
Typical Applications
Industrial sector
Temperature monitoring and control of pipelines, reactors, and equipment in the chemical, metallurgical, and power industries.
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In the automotive field
Accurate measurement of engine coolant temperature and transmission oil temperature
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Medical field
Temperature calibration and monitoring of medical equipment such as blood analyzers and dialysis machines.
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High end household appliances
Temperature sensing and regulation for precision refrigerators and constant temperature ovens
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Laboratory and Metrology
Temperature detection using standard temperature calibration devices and environmental testing chambers.
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