MIEPL make MTT09 Thermocouple are the most common, convenient, and versatile devices used to measure temperature. They convert units of heat into useable engineering units that serve as input signals for process controllers and recorders. A thermocouple consists of a welded 'hot' junction between two dissimilar metals, usually wires and a reference junction at opposite ends of the parent materials. Mainly used in Power, Chemical,steel and Oil Industries.