Dealing with Definitional Uncertainty Better Measurements in Power Systems

There is a relationship between the user of the result of a measurement and the act of measurement that should guide the act: the user has some specific need for the meaning contained in the result. The extent to which that need is met is a measure of the quality of the measurement. The usual quality metric is the measurement uncertainty. This paper shows that, because of significant signal distortion accompanying measurements in power systems, the uncertainty may be inappropriate outside the calibration laboratory. We propose a way to improve the situation. Better measurements are not necessarily ones with faster response or greater precision: the important point is that they meet the needs of the user. They are “fit for purpose.” The solution proposed here affects both the instrument designer and the user. It requires that additional information regarding uncertainty accompany all result values (not just those done in the calibration laboratory), and it requires changes to the way the results are handled by the user. The paper concentrates on electric power system measurements, but it is hoped that the ideas can be applied more broadly to other field measurements.