Uncertainty of temperature measured by thermocouple

Abstract

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. In this research, four error sources were proposed to have contributed in the uncertainty of temperature measured by a thermocouple which were resolution limit of data acquisition device, error in temperature measurement based on voltage measurement, reference junction compensation error and data fluctuation. Experiments were carried out to obtain reference junction compensation error and data fluctuation using HIOKI data logger (LR8400-20). The procedure to obtain the uncertainty of the measured temperature including the reference junction compensation uncertainty is proposed. The uncertainty was obtained by combining all the error values with root-sum-square equation. The uncertainty for K thermocouple obtained from this research was 0.42 °C.