Thursday, January 31, 2019


thermocouple circuit
Diagram of a thermocouple circuit.
A thermocouple is a temperature measurement sensor. Thermocouples are made of two different metal wires, joined to form a junction at one end. The connection is placed on the surface or in the measured environment. As the temperature changes, the two different metals start to deform and cause resistance changes. A thermocouple naturally outputs a millivolt signal, so that the change in voltage can be measured as the resistance changes. Thermocouples are desirable because they are extremely low cost, easy to use and can provide precise measurements.

Typical sheathed thermocouple.
Thermocouples are produced in a variety of styles, such as sheathed, washer type, bayonet,  mineral insulated, hollow tube, food piercing, bare wire thermocouples or even thermocouple made from thermocouple wire only.

Because of their wide range of models and technical specifications, it is extremely important to understand their basic structure, functionality and range in order to better determine the right thermocouple type and material for an application.

Operating Principle

When two wires consisting of different metals are connected at both ends and one end is heated, a continuous current flows through the thermoelectric circuit. If this circuit is broken in the center, the net open circuit voltage (Seebeck Effect) depends on the temperature of the junction and the composition of the two metals. This means that a voltage is produced when the connection of the two metals is heated or cooled that can be correlated to the temperature.

Contact Duro-Sense Corporation with any questions about applying industrial and commercial thermocouples.

Duro-Sense Corporation