Final report on key comparison CCEM-K12: AC–DC current transferstandards

Abstract

The circulation of the travelling standards in the CIPM key comparison CCEM-K12 of AC–DC current transfer difference began in March 2005 and was completed in April 2007. The travelling standards were lost on their way from the last participant to the pilot laboratory. Since, prior to their disappearance, the travelling standards exhibited exceptional stability, the CCEM Working Group on Low-Frequency Quantities decided in June 2008 to accept the results of the comparison as valid without the final measurement by the pilot laboratory.The AC–DC transfer differences of the travelling standards have been measured at 10 mA and 5 A, and at the frequencies 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz and 100 kHz. The key comparison reference values were calculated as the weighted means of the results of the National Metrology Institutes (NMIs) with independent realizations of primary standards and low reported uncertainties. The degrees of equivalence relative to the key comparison reference values, as well as between pairs of NMIs, have been determined for the measurement points and show very good agreement. All but three of the calculated degrees of equivalence relative to the key comparison reference values are within the limits of the expanded uncertainties.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 the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).