A Fundamental Step-Up Method for Calibrating Active Compensated Current Comparator Standards at Power Frequencies

This article presents a step-up method for calibrating a set of error compensated current comparators (CCs) for currents from 4 A to 60 kA from the Physikalisch-Technische Bundesanstalt (PTB)'s instrument transformer laboratory for the use as reference standards for calibrating current transformer (CT). The method is based on some hypotheses and previous knowledge about the error characteristics of a current comparator of the set. Extensive measurements between the CCs confirm the hypotheses in the order of 10(-7) and show for the CCs that their ratios and phase errors and corresponding uncertainties are also in the range of 0.1 mu A/A and 0.1 mu rad.