Type S thermocouples are constructed using one wire of 90% Platinum and 10% Rhodium (the positive or “+” wire) and a second wire of 100% platinum (the negative or “-” wire). -Like type R, type S thermocouples are used For High Temperature Sensing up to 1500 °C.
The thermocouple working principle is based on the Seeback Effect. This effect states that when a closed circuit is formed by jointing two dissimilar metals at two junctions, and junctions are maintained at different temperatures then an electromotive force (e.m.f.) is induced in this closed circuit.