Research of the Method For Measuring Temperature with a Two-Wire Connection of a Resistance Thermometer

Abstract

Purpose: study of a method for measuring temperature with a two-wire connection of a resistance thermometer (RT) using its mathematical model. Conduct model testing and research to evaluate the potential capabilities of the measurement information processing method, which is based on determining the resistance of the vehicle based on the results of integrating the transient process in the measuring circuit after turning off its power source, determine the parameters of the measuring circuit and the algorithm underlying the method . For a given range of measured temperatures, determine the type and parameters of the adaptive measurement algorithm model.Methods: methods of mathematical modeling, numerical methods. When developing a mathematical model of the method, the theory of electrical circuits was used, in particular, the analysis of transient processes. When analyzing the proposed solutions, the impact of electromagnetic interference and quantization effects was taken into account, and the effectiveness was assessed by the relative error () of measuring the resistance of the vehicle and comparison with analogues. The simulation was carried out in the MATLAB environment.Results: a mathematical model of an integrating method for measuring temperature using a TS was developed, the optimal value of the shunt capacitance was selected for the range of measured temperatures 0 ... 660 °C, providing within the range the calculated value of the root-mean-square error (RMS) of 0.02% -0.04%, the optimal value was determined first integration interval (4 ms). It is shown that for the adaptive measurement algorithm it is possible to select a linear model. The effectiveness of the method was assessed in comparison with the method of determining the resistance of the vehicle using two readings of the transient process.Conclusion: The results of mathematical modeling of a method for measuring temperature based on estimating the resistance value of a vehicle based on the results of numerical integration of the transient discharge process of a capacitor connected in parallel with a resistor are presented, making it possible to optimize the algorithms underlying its operation, as well as to judge the effectiveness of the proposed solution. The two-wire method, based on determining the resistance of the vehicle based on the results of integrating the transient process when the power of the measuring circuit is turned off, makes it possible to increase the accuracy of temperature measurement comparable to the accuracy of three and four-wire circuits, eliminating the disadvantages associated with their complexity and high cost.