Supplementary comparison for the traceability of AC high voltage reference measuring systems up to 200 kV (EURAMET.EM-S33)

Abstract

Main textThe intercomparison consisted of calibrating a High Voltage Travelling Reference Measuring System, TRMS, using peak and rms voltage values, at the frequency of 50 Hz and with voltages of 750 V, 1 kV, 40 kV, 80 kV, 120 kV, 160 kV and 200 kV.The TRMS consisted of a capacitive divider with fixed input and grounding leads, a coaxial cable, a HP 3458A digital multimeter and a computer with a printer. The TRMS had two ranges, 20 kV and 200 kV, depending on the low voltage arm connected to the high voltage capacitor. The TRMS included the low voltage digital multimeter, in such a way that the measuring error of high voltage TRMS should be measured to determine the scale factor of the high voltage divider. Intercomparison results are expressed as the scale factor of the travelling high voltage capacitive divider, the scale factor is dimensionless.Complementary low voltage measurements were also performed to check how the peak voltage is evaluated when harmonics or distortion are superimposed to sinusoidal waveforms. To evaluate this performance an arbitrary waveform generator was included among the travelling devices in such a way that it was possible to compare the peak voltage measured by the TRMS using the provided digital multimeter and the specific intercomparison software and the peak voltage measured by each participant.The coordinating laboratory was LCOE (Spain) and the participating institutes were LNE (France), VTT MIKES (Finland), RISE (Sweden), TÜBITAK UME (Türkiye), PTB (Germany), BIM (Bulgaria), INRiM (Italy), VSL (Netherlands), VNIMS (Russia) and LCOE (Spain).Results of the comparison proved the calibration and measurement capabilities, CMCs, of the participants in the field of high voltage AC measurement, especially when performing peak hv measurements up to 200 kV with expanded uncertainties in the range of 40 mV/V to 80 mV/V.The discrepancy between the results of the two labs claiming the lowest uncertainties, PTB and VTT, was on some measurements significantly larger than the respective uncertainties. One of these labs redesigned its measuring system and a subsequent bilateral comparison arranged between PTB and VTT solved the discrepancy.Undertaking the work collaboratively through EURAMET proved to be an excellent tool to compare calibration and measurement capabilities of NMI and DI, as well as an opportunity for several institutes to improve their CMCs.To 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 https://www.bipm.org/kcdb/.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).