Technical Blog

How Does a Thermocouple Work?

A thermocouple is a type of temperature sensor. Essentially, a thermocouple works by creating an electric current which is used to measure temperature.

What is a Thermocouple?

To have a full understanding of how a thermocouple works, it’s important to know what a thermocouple is. A Thermocouple is a type of temperature sensor which is made up of two wires of dissimilar metals. It measures temperature using the Seebeck effect.

There are many different types of thermocouples, each one has it’s own unique characteristics for temperature range, vibration resistance, durability, chemical resistance, and application compatibility. Type J, K, T, & E are known as “Base Metal” thermocouples which are the most common types of thermocouples. Type R, S, and B thermocouples are “Noble Metal” thermocouples, these are commonly used in high-temperature applications.

How Does a Thermocouple Work?  In more detail

When a metal comes into contact with heat, the heat is conducted through the metal by charged atoms – electrons. Thomas Seebeck, a German physicist, discovered that when metal is heated, and the temperature is conducted from one end to the other, electricity is also being generated and conducted. However, it is not possible to create an electrical circuit from this electricity. Once the metal is joined into a loop, the metal becomes the same temperature, losing the electrical current.

Different metals conduct heat and electricity at different speeds and produce a different current from each other when heated to the same temperature. By taking two strips of dissimilar metals which are the same size and joining them together at each end a loop is created. By making one of the joins in the metal very hot and the other join very cold, an electric current will flow through the loop creating an electric circuit.

The size of the current is dependent on the difference in temperature between the two ends. Therefore a formula can be created which will convert the current into a temperature reading.

This is how a thermocouple works. Each type contains two different metals and measures the temperature of something by calculating the electrical current which is then fed into a formula.

Why use a Thermocouple? 

A thermocouple can measure both higher and lower temperatures than a standard temperature sensor. They are generally low cost and durable making them well suited to industrial applications including OEM, oil and gas, BioTech, pharmaceutical to name a few. They are also present it many household appliances such as toasters, stoves and furnaces.  

We can offer a range of thermocouples for many applications. Take a look at our General Purpose Thermocouples, Miniature Thermocouples and Mineral Insulated Thermocouples. If you require further information please contact us using the details above.  

Article published on: 04/03/2015