Thermocouples – Temperature Mearurement
A thermocouple is a device for measuring temperature. It comprises two dissimilar metallic wires joined together to form a junction. When the junction is heated or cooled, a small voltage is generated in the electrical circuit which can be measured and this corresponds to temperature.
In theory any two metals can be used to make a thermocouple but in practise there are a fixed number of types that are commonly used. They have been developed to give improved linearity and accuracy and comprise specially developed alloys.
Thermocouples can be made to suit almost any application. They can be made to be robust, fast responding and to measure a very wide temperature range.
Each of the thermocouple types is given a coding letter to denote each of the alloy combinations. The most common code letters are K, J, T and N. Other types include R, S, E, B, C, G and W. The most popular being the type k thermocouple.
Each thermocouple type has its own alloy pair which are carefully selected and calibrated to meet the international standards to which we must comply. The standard that governs thermocouples in the UK and Europe is BS EN 60584 and covers the characteristics, tolerances and colour coding of the different thermocouple types.