Comparison of ac voltage in the mV-range

Project Description

The objectives of the comparison are to determine the level of equivalence between the participating National Measurement Institutes within the EUROMET region.

The results of the comparison will also be used to improve the calibration methods and to harmonise the evaluation of uncertainty contributions. The objectives of the comparison will be realised as follows: A solid state thermal transfer standard with amplified mV-ranges will be used as the travelling standard. The comparison will be organised in three loops of about four laboratories in each loop. The pilot laboratory will make measurements before and after each loop to monitor the stability of the travelling standard. The ac-dc transfer difference of the travelling standard is to be measured at the voltages 10 mV and 100 mV and at the frequencies 1 kHz, 20 kHz, 100 kHz and 1 MHz.

The period of measurement allocated for each laboratory is one month including transportation. Each participant must report the result of the measurement to the pilot laboratory, clearly describing the measuring method and analysing the uncertainty contributions. The calculation of the uncertainty shall be made according to the ISO guide to the expression of uncertainty or the EAL document EAL-R2, Expression of the uncertainly of measurement in calibration.

As the CCEM-K11 is about to finish this comparison is now started and the circulation of the travelling standard will begin Aug 2005
Project to be included in the EUROCOMP and presented to the 5th SMT program.

Final Report 2011-10-06

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

The regional key comparison EURAMET.EM-K11 “ac-dc voltage transfer difference at low voltages” between National Metrology Institutes (NMIs) has been finalized. The aim of the comparison was to determine the Degree of Equivalence (DoE) between the participating NMIs and to link them to the participants of the CIPM key comparison CCEM-K11. A total of 21 NMIs participated in the comparison, most of them members of EURAMET (one withdraw after the draft A report) but three NMIs from AFRIMETS, APMP and COOMET also participated. The measurements were carried out in the period July 2005 to April 2008.
The travelling standard, an ac-dc transfer standard with amplified low voltage ranges 220 mV and 22 mV, was very stable during the comparison. The ac-dc voltage transfer difference of the travelling standard was measured at 100 mV and 10 mV and at the frequencies 1 kHz, 20 kHz, 100 kHz and 1 MHz. The comparison reference values (CRVs) were calculated as the weighted mean of the results of the NMIs with independent realisations. The DoE relative the CRV and between pairs of NMIs have been determined and show good agreement. The DoEs relative the KCRV of the CCEM-K11 are also good. The vast majority of the calculated deviations are within the limits of the expanded uncertainties.

The final report is sent for publication in the BIPM KCDB.