A thermocouple is a device used extensively for measuring temperature.

A thermocouple is composed of two wires made from dissimilar metals. These two wires are joined to form a temperature measurement junction. Each wire is made of a specific metal or metal alloy. For example, the positive (+) conductor of a type K thermocouple is made of a chromium/nickel alloy called chromel and the negative (-) conductor is made of an aluminium /nickel alloy called alumel. Wire used to make a thermocouple junction is called thermocouple wire.

How Do I Choose a Thermocouple

1. Determine the application for which the thermocouple will be used.
2. Note the maximum and minimum temperatures the thermocouple will be exposed to.
3. Factor in any chemical resistance required for the thermocouple .
4. Evaluate the need of abrasion and vibration resistance.
5. List any installation requirements

Advantages of the Thermocouples:-
• Thermocouples are used on most transformers. The hot junction is inside the transformer oil and the cold junction at the meter mounted on the outside. 
• In general, thermocouples are used exclusively around the turbine hall because of their rugged construction and low cost.