Bilateral Comparison of 10 V Standards between the NSAI - NML (Ireland) and the BIPM, March 2015 (part of the ongoing BIPM key comparison BIPM. EM-K11.b)

As part of the ongoing BIPM key comparison BIPM. EM-K11.b, 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 February and March 2015. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_6 (Z6) and BIPM_C (ZC), 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. 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 resultof the comparison is presented as the difference between the values assigned to DC voltage standards by NSAI - NML, at the level of 10 V, at NSAI - NML, U-NML, and those assigned by the BIPM, at the BIPM, U-BIPM, at the reference date of 24 February 2015. U-NML - U-BIPM = - 0.82 mV; u(c) = 1.35 mV, at 10 V where u(c) is the combined standard uncertainty associated with the measured difference, including the uncertainty of the representation of the volt at the BIPM and at NSAI-NML, based on KJ-90, and the uncertainty related to the comparison.