Isaiev V. Improvement of means and methods of metrological support of precision measurements of alternating current and alternating voltage

Thesis is devoted to the search for ways to create and improve state standards of units of alternating current and voltage, as well as methodological support of precision measuring equipment, which provide metrological traceability to the specified standards. A comparative analysis of the methods and means, used for metrological support of precision measurements of alternating current and voltage in national metrological institutes of states with verified calibration and measurement capabilities, was carried out in the work. The results of the analysis allowed us to formulate an approach to solving the problem of precision measurements of the alternating current. The method of thermoelectric comparing of the root-mean-square value with an equivalent direct current was chosen. The basis for constructing high precision standard was developed, a study of the metrological characteristics of the components was carried out, the sources of measurement uncertainty were analyzed. The instability for 14 years was analyzed by the existing procedure in order to improve the State standard of alternating voltage unit. A metrology procedure was improved to expand the observation range of this characteristic. It was proposed to reduce the measurement uncertainty when calibrating the AC measuring instruments by determining the temperature dependence of the Fluke 792A thermal comparator and observing equal time intervals between measuring the input voltages. Operational and regulatory documents were analyzed to create methodological support for the calibration of alternating current comparators and measures of power quality parameters. The approaches were formed to solving these issues by constructing measuring circuits, optimizing functional relationships and analyzing sources of uncertainty. In order to evaluate equivalence of precision alternating voltage measurements, the study was conducted by comparing the measurement results of the phase angle between two voltages by means of two methods (using precision voltmeter or precision phase meter). The inter-laboratory comparison was conducted to establish the metrological traceability of the measurement results of calibrating thermal voltage converter, obtained by the calibration laboratories of Ukraine, to the international system of units SI.