Measurement Uncertainty Evaluation of Results Provided by Transducers Working in Control Loops

摘要

Evaluation of measurement uncertainties covers uncertainty propagation from sources to a measured quantity. Phenomena taking place inside measuring transducers are typically considered applying Type B evaluation. It is evidenced in this work, that transducers included in a closed-loop control system should be treated in a different way because their uncertainty sources propagate through the dynamic system and change their limits of variabilities. Depending on frequencies, the limits may be either similar or lower or even higher. An especially dangerous case takes place when the variability at the output of the plant is greater than at the output of the transducer. In this work, such cases are presented and discussed.