What is the Difference Between RTD and Thermocouple?

The main difference between RTDs (Resistance Temperature Detectors) and thermocouples lies in their sensing elements and their characteristics. Here are the key differences between RTDs and thermocouples:

RTDs:

• Use a resistive wire element.
• More accurate with a temperature accuracy of ±0.5°C.
• Better suited for lower temperature ranges.
• Have a slower response time compared to thermocouples.
• More expensive than thermocouples.
• Unsuitable for temperatures over +850 degrees Celsius.
• Linear output.
• High stability and repeatability.

Thermocouples:

• Use two dissimilar metals joined together at one end, creating a junction.
• Less accurate with an accuracy of ±2°C.
• Can measure a higher range of temperatures.
• Faster response time compared to RTDs.
• Cheaper than RTDs.
• Can withstand higher temperatures and harsher conditions.
• Non-linear output.
• Less stable and less repeatable than RTDs.

When choosing between RTDs and thermocouples, consider factors such as accuracy, temperature range, response time, cost, and the specific conditions of the application. RTDs are better suited for lower temperature ranges where higher accuracy, stability, and repeatability are required, while thermocouples are more suitable for high-temperature and high-vibration processes with fast response times.

Comparative Table: RTD vs Thermocouple

Here is a table comparing the differences between RTDs (Resistance Temperature Detectors) and thermocouples:

In summary, RTDs offer higher accuracy and sensitivity, making them suitable for precise temperature measurements. However, they have a narrower temperature range and slower response times compared to thermocouples. Thermocouples excel in ruggedness, have a broader temperature range, and faster response times, but they provide lower accuracy and sensitivity than RTDs. It is essential to consider the specific requirements of an application when choosing between RTDs and thermocouples.