Comparison of resistance standards at 10 MΩ and 1 GΩ

Project Description

DC Resistance is one of the key quantities selected by the CIPM Consultative Committee for Electricity and Magnetism (CCEM). A CIPM key comparison of resistance at the 10 MΩ and 1 GΩ level (CCEM-K2) was carried out between 1996 and 2002 and approved for full equivalence in 2002. In order to link the National Metrology Institutes organized within EUROMET to the key comparison CCEM-K2, the EUROMET technical committee for electricity and magnetism decided at its October 2004 meeting to carry out the corresponding RMO key comparison.

The comparison will be organized in two parallel loops. In each loop three 10 MΩ and three 1 GΩ standards will be circulated among the participants. The period of measurement allocated for each laboratory is one month including transportation. The pilot laboratory will make measurements before in the middle and after the loops to determine the drift behavior of the traveling standards.
This comparison will be organized following the CCEM guidelines for planning, organizing, conducting and reporting key, supplementary and pilot comparisons.
The proposed time schedule for the measurements is July 2005 to August 2006.

The App B identifier of this key comparison is EUROMET.EM-K2

Final Report 2010-04-30

The comparison has been completed and results are published in the KCDB.

Twenty-four National Metrology Institutes, among them twenty-two EURAMET members, partici-pated in the comparison EUROMET.EM-K2 aimed at evaluating the degrees of equivalence of the measurements of 10 Mohm and 1 Gohm resistance standards. The link to the CCEM comparison CCEM-K2 and the degrees of equivalence with respect to the key comparison reference value were also evaluated. With three exceptions at 10 Mohm, all results supplied by the participants agreed with the comparison reference value within the expanded uncertainty.

The method of constrained least squares was applied to calculate the comparison reference value.  This method has proven to be useful in this analysis, because it provides a single, consistent and transparent approach for the determination of the key values of this measurement comparison in-volving multiple artefacts and overlapping loops.