How to measure thermocouple

Temperature is the measure of the average kinetic energy of particles in a sample. The standard unit is “degree”. The temperature can be measured by different methods, and the cost and accuracy of the measurement are different. A thermocouple is one of the most common sensors for measuring temperature because thermocouples are relatively inexpensive and accurate, and their measurement ranges are relatively wide.

Whenever two different metals come in contact, the contact point produces a lower no-load voltage as a function of temperature, which is the thermoelectric effect. This thermoelectric voltage is the Seebeck voltage, named after physicist Thomas Seebeck, who discovered the phenomenon in 1821. This voltage is non-linear with respect to temperature, but can be approximated as linear for a small range of varying temperatures, or:

∆V=S∆t

In the equation, ∆V is the voltage change, S is the Seebeck coefficient, and ∆T is the temperature change.

There are many types of thermocouples and they are all stipulated by the American National Standards Institute (ANSI) convention, and their composition is indicated by larger letters. For example, a J-type thermocouple consists of an iron conductor and a copper-Nickel Alloy conductor. Other types of thermocouples include B, E, K, N, R, S, and T.

How to Measure Thermocouples To better understand how to perform thermocouple measurements, you must first understand how thermocouples work. The first part of this document will explain the basic principles of thermocouples, and later sections will explain how to implement the connection between the thermocouple and the instrument and how to measure the temperature.

The thermocouple Seebeck voltage is directly connected to the measurement system and connected to the measurement system will generate an additional temperature difference circuit, so it cannot be measured by simply connecting it to a voltmeter or other measurement system.