Reliability Evaluation of the Thermocouple Reference Junction

Abstract

Reference junction is one of the most important instruments for thermocouple measurement. On a factory floor of the industrial world, such as heat treat furnace and production line, the reference junction compensation is most commonly used in thermocouple measurement.

In recent years, temperature measurement is required at the level of high precision. There are, however, some disadvantages to using reference junction compensations - notably its lack of accuracy. Therefore, when implementing the high level of sensitivity and accuracy during temperature measurement, the reference junction such as “crushed ice and cold water” (ice point) are effectively used.

For the purpose of an improved reliability in temperature measurement with thermocouples, we evaluated the reliability of the reference junction compensation and the reference junction (in terms of ice point, automatically-operated ice point device and high precision water bath), and compared with both results. The results of the evaluation were different from the utility of each instrument. When working with thermocouples, it was possible to achieve further reliability improvement in the temperature measurement.