Key comparisons CCEM-K8 and EUROMET.EM-K8 on DC voltage ratio were carried out in parallel, both having the Istituto Elettrotecnico Nazionale G Ferraris (IEN) as the pilot laboratory. Two Datron 4902S voltage dividers were used as travelling standards, each divider being dedicated to one comparison. On these dividers the measurements of the ratios 1000 V/10 V and 100 V/10 V were mandatory and were used to evaluate the degrees of equivalence of the participants with respect to the reference value of their own comparison.

The reference value of a key comparison carried out by a Consultative Committee of the CIPM, like CCEM-K8, is called the Key Comparison Reference Value (KCRV), and the degrees of equivalence of a regional comparison, like EUROMET.EM-K8, must be translated in terms of the KCRV. The two comparisons under study concern the measurement of voltage ratios, hence no national standard is involved. Then any participant in both comparisons can be considered equally able, in principle, to perform an unbiased measurement of the travelling standard. Since the number of participants in each comparison is significant and different methods of measurement were used, it is unlikely that the corresponding comparison reference value is affected by systematic errors. The degrees of equivalence with respect to the KCRV of the participants in EUROMET.EM-K8 are then the same as those with respect to the reference value of EUROMET.EM-K8.

The extended linking document reports a verification of such an assumption, based on the results of the common laboratories of the two comparisons.

Main text. To reach the main text of this paper, click on Linkage Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The linkage report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the Mutual Recognition Arrangement (MRA).