Bilateral Comparison of 1 V and 10 V Standards between the DMDM (Serbia) and the BIPM, January to March 2014 (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)

As part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1 V and 10 V voltage reference standards of the BIPM and the Directorate of Measures and Precious Metals (DMDM), Beograd, Serbia, was carried out from January to March 2014. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_6 (Z6) and BIPM_A (ZA), were transported by freight to DMDM. At DMDM, the reference standard for DC voltage is a Josephson Voltage Standard. The output electromotive force of each travelling standard was measured by direct comparison with the primary standard. At the BIPM, the travelling standards were calibrated, before and after the measurements at DMDM, with the Josephson Voltage Standard. Results of all measurements were corrected for the dependence of the output voltages of the Zener standards on internal temperature and ambient atmospheric pressure. The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by DMDM, at the level of 1.018 V and 10 V, at DMDM, UDMDM, and those assigned by the BIPM, at the BIPM, UBIPM, at the reference date of the 13 February 2014. UDMDM − UBIPM = 0.094 µV; uc = 0.072 µV, at 1 V UDMDM − UBIPM = 0.39 µV; uc = 0.12 µV, at 10 V where uc is the combined standard uncertainty associated with the measured difference, including the uncertainty of the representation of the volt at the BIPM and at DMDM, based on KJ-90, and the uncertainty related to the comparison. The results at the 10 V level are not covered by the uncertainties with a coverage factor of 2. After the distribution of the Draft A, the DMDM discovered that the pressure gauge was defective. Some considerations on the correction to apply on the comparison result and the corresponding uncertainties are presented in the report. Nevertheless, the above results fully cover the CMCs of DMDM which are significantly larger. No corrections for temperature and pressure are applied in calibrations for customers' secondary standards. 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).