RTD Error Correction in the Diagnostics of its Parameters State

The paper deals with the problem of estimating the error of a copper resistance-temperature detector (RTD) in the diagnostics of the state of its transformation function parameters. The evaluation of the measured temperature, depending only on the relative change of the temperature coefficient of the resistance-temperature detector, is obtained. To assess the impact of changing the parameters from their nominal values, the effect of the influence of the measuring current on the measurement result is used, which consists in overheating of the sensitive element of the RTD in accordance with Joule-Lenz's law. The information obtained as a result of additional measurements is the basis for correcting the multiplicative component of the measurement error of temperature. The experimental data obtained during the aging of copper RTDs for 10,000 hours have been processed. The increase in the effectiveness of the proposed assessment of the measured temperature with increasing the lifetime of the RTD is shown. The considered approach makes it possible to perform the diagnostics of the RTD state and implement the self-validation feature, or metrological self-monitoring, in temperature transmitters.