Implementation of Uncertainty Analysis of Temperature Measurement

Abstract

Thermocouples is a common and widely used device in many industrial, scientific and OEM applications. As a temperature sensor, thermocouple is used in measuring temperature. Reliability of data is important for researchers to verify their research result. For temperature measurement involving thermocouple, uncertainty needs to be determined before deciding the reliability of data. There are plenty of ways researchers have tried to get the uncertainty of thermocouple by using other equipment, but for data loggers an easier and faster way to obtain the RJC error is strongly required. Hence, a new easier and faster way to obtain the RJC error was proposed in this research. The purpose of this research was to obtain the result of reference junction compensation in parallel connection throughout 15 channels in a data logger with a shorter time taken, efficiently and accurately than series connection. Experiments were carried out by using HIOKI data logger (LR8400-20) connecting with thermocouple. Thermocouples consist of two wire legs made from different metals. The wires legs are welded together at one end, creating a junction. This junction is where the temperature was measured while the wire is connected to each other parallel on the data logger terminal. Three error sources were proposed to have contributed to the uncertainty of temperature measured by a thermocouple which were resolution limit of data acquisition device, reference junction compensation error and random error. The uncertainty was obtained by combining these three error values with the root-sum-square equation.