Bilateral comparison of 10 V standards between the NSAI-NML (Ireland) and the BIPM

As part of the ongoing BIPM key comparison BIPM.EM-K11, a comparison of the 10 V voltage reference standards of the BIPM and the National Standards Authority of Ireland - National Metrology Laboratory (NSAI - NML), Dublin, Ireland, was carried out in November and December 2020. The objective for NSAI-NML in participating in this comparison was to demonstrate the international equivalence of its DC voltage measurement results and to support their calibration and measurement capabilities (CMCs) published in the Key Comparison Database of the BIPM (KCDB). Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_8 (Z8) and BIPM_9 (Z9), were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage at the 10 V level consists of a group of characterized Zener diode-based electronic voltage standards. The output EMF (Electromotive Force) of each travelling standard was measured by direct comparison with the group standard. At the BIPM the travelling standards were calibrated, before and after the measurements at NSAI-NML, with the Josephson Voltage Standard, developed at the BIPM. The output EMF of each travelling standard was measured against the Josephson Voltage Standard (JVS). 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 comparison result is presented as the difference between the value assigned to a 10 V standard by NSAI-NML, at NSAI-NML, U NSAI-NML , and that assigned by the BIPM, at the BIPM, U BIPM , on the reference date of 2020/11/14, as U NSAI-NML - U BIPM = -2.99 µV; u c = 1.71 µV where u c is the combined standard uncertainty associated with the measured difference, including the uncertainty of the realization of the volt at NSAI-NML, and the uncertainty related to the comparison. 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 https://www.bipm.org/kcdb/ . 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).