Bilateral comparison of 1.018 V and 10 V standards between the KEBS (Kenya) and the BIPM, January to March 2018, (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)

Abstract

As part of the ongoing BIPM key comparison BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and the Kenya Bureau of Standards, was carried out from January to February 2017. Two BIPM Zener diode-based travelling standards (Fluke 732B), BIPM_A (Z8) and BIPM_B (ZB), were hand carried to KEBS and back to BIPM by M. Gibosn Aguko. Since the total duration of the travels from one institute to the other was not exceeding the capabilities of the self-powering of the Zeners (36 hours), the transfer standards did not need any additional battery connected in parallel to the internal battery. At KEBS, the reference standard for DC voltage is a 732B Zener standard traceable to a primary voltage by means of a calibration service requested once a year from a National Measurement Institute (UME, Turkey) operating a Josephson Voltage Standard (JVS) two times per year. The output EMF (Electromotive Force) of each travelling standard was measured against the Zener voltage standard by means of an accurate multimeter.At the BIPM, the travelling standards were calibrated, before and after the measurements at KEBS, 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 atmospheric pressure.Since KEBS did not record the temperature of the internal voltage reference during its measurement session, no correction for the Zener temperature dependence was applied. However, as a consequence the related uncertainty was adjusted.The final result of the comparison is presented as the difference between the values assigned to DC voltage standards by KEBS, at the level of 1.018 V and 10 V, at KEBS, U KEBS, and those assigned by the BIPM, at the BIPM, U BIPM, at the reference dates of the 2 February 2018. U KEBS - U BIPM = + 0.11 µV; u c = 0.34 µV, at 1.018 V U KEBS - U BIPM = + 0.25 µV; u c = 1.55 µV, 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 KEBS, based on KJ-90, and the uncertainty related to the comparison. KEBS' uncertainties appear to be over estimated and would require revision.KEY WORDS FOR SEARCHJosephson voltage standard; Zener diode; KEBS; BIPM; comparison; Kenya; electricity and magnetism; CIPM MRAMain textTo 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).