I wish I knew how temperature measurement works!

This answer will depend on which sensor you use in your process because each measures temperature differently. So I’ve listed the most common sensors you’ll find in the field and the idea behind each.

How temperature measurement works
Courtesy of Endress+Hauser
  • Thermocouple: This sensor has two metals welded at one end, producing the phenomenon called the thermoelectric effect. When you heat the sensor, the temperature differs in each metal, creating a voltage at the other end. This voltage is proportional to the heat affecting the sensor. So by using a reference table, you can see the relationship between the voltage and the temperature.
  • Resistance temperature detector (RTD): This sensor detects resistance. The device applies a direct current, so when the temperature changes, the resistance changes proportionally to the temperature.
  • Infrared sensor: All objects emit energy. The infrared sensor can measure the energy emitted from an object and through thermal frequency distribution find the temperature.

You can learn more about temperature sensors in these links:

  • Your friendly neighborhood temperature sensor! In most cases, you need to monitor exact temperatures, and in some, you need precise control. When you learn about temperature sensor from the maintenance point of view, you’ll find that you only need to consider certain points to choose the right sensor for your application.

  • Thermocouple – How to read reference tables: When I wrote about thermocouples, I mentioned needing tables to translate your data from millivolts to temperature. You probably think that if you connect the sensor to the transmitter, then you don’t need a table to find the temperature.

    How temperature measurement works

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