The Euromet comparison entitled 'Comparison of the measurement of current transformers' was carried out over two projects with NPL as pilot laboratory and thirteen other participating European National Measurement Institutes (NMI). Current transformer measurements made by the participating NMIs support a large number of measurements made in the electrical generation, supply and distribution industries in their own countries. They also support many transformer manufacturers who rely on national standards as a source of traceability. The current (ratio) errors and phase displacement of each ratio of the uncompensated current transformer transfer standard were determined at a defined frequency, burden and power factor, using each participant's standard measuring method and equipment.

The results supplied by each participant generally show good agreement but with a few exceptions over the whole range of measured values. Deviations from the comparison reference value were mostly within the quoted uncertainties, but again with a few exceptions. A summary of outlying results compared to laboratories' declared Calibration and Measurement Capabilities (CMC) is given in the conclusion. In several cases participants have been making current transformer measurements with new measurement systems and techniques, and in one case for the first time; therefore a large amount of experience in the measurement and interpretation of results has been obtained from this comparison.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).