Choosing the right temperature sensor is a critical element of any measurement system. The two most popular types are thermocouples and RTDs (Resistance Temperature Detectors). Each has its advantages and limitations. So how do you decide which sensor is best for your application?
Thermocouples – When Are They the Best Choice?
Thermocouples operate based on the Seebeck effect – they generate a voltage proportional to the temperature difference between two points of a junction made from different metals. They are extremely versatile and widely used in industrial applications.
Advantages of thermocouples:
- Very wide measurement range (up to 1800°C for types B, S, or R),
- Fast response time,
- Resistant to vibration and extreme conditions,
- Low production cost.
When to choose a thermocouple:
Thermocouples are best suited for high-temperature environments, such as industrial furnaces, internal combustion engines, turbines, or metallurgical processes. They are indispensable where response time and resistance to harsh conditions matter most.
RTDs – When Is a Resistance-Based Measurement Better?
RTDs, such as the popular Pt100 or Pt1000 sensors, work based on the change in resistance of a conductor (usually platinum) in response to temperature. They are known for their precision and repeatability.
Advantages of RTDs:
- High measurement accuracy (up to ±0.1°C),
- Excellent long-term stability,
- Accurate calibration possible,
- Less susceptible to electromagnetic interference.
When to choose an RTD:
RTDs are ideal for applications requiring accuracy and stability – such as laboratories, refrigeration, pharmaceutical and food industries, and HVAC automation.
Comparison – Thermocouple vs RTD
| Feature | Thermocouple | RTD |
|---|---|---|
| Measurement range | –200°C to +1600°C | –200°C to +550°C |
| Accuracy | Moderate | High |
| Response time | Very fast | Fast |
| Resistance to conditions | High | Moderate |
| Cost | Low | Higher |
Why Is System Matching So Important?
Choosing the right temperature sensor is just one part of the system. Equally important is matching the temperature transmitter and temperature controller to the sensor type. Thermocouples and RTDs generate different signals, require different signal conditioning circuits, and have unique calibration requirements. Only a properly matched set will provide reliable temperature measurement and trouble-free system performance.
Conclusion
If you need high accuracy and stability – choose an RTD. If your application involves very high temperatures or harsh environments – go with a thermocouple. As a manufacturer of temperature sensors, we offer both standard and custom sensors tailored to your individual needs.
Still not sure? Contact us! Our specialists will be happy to help you.