Research on Measurement Algorithm of Thermocouple Time Constant Under Multiple Incentive Experimental Conditions

ABSTRACT The time constant is often an important indicator parameter to evaluate the response speed of thermocouples. However, in practical applications, the output signal suffers from interference and deformation due to the excitation signal not satisfying the desired step size, data transmission delay, and the effect of mechanical vibrations, which do not match the output response of the system of the same order. In addition, the measurement results are not reproducible due to the subjective influence of the manual measurement method. In this paper, we propose a method to compute the time constant. The output signal is modified by filtering and fitting to enable the automatic calculation of the time constant, and the parameters of the algorithm are discussed. We developed a thermocouple time constant measurement device using a water bath and laser excitation conditions, obtaining response signals from thermocouples with different wire diameters and laser powers. The results demonstrate the effectiveness of the proposed time constant calculation methods in accurately capturing the changing trend of thermocouples with different wire diameters and laser powers. These methods successfully meet the requirements for processing the dynamic response signals of thermocouples under various excitation conditions.