Supplementary comparison EURAMET.EM-S42, comparison of lightning impulse (LI) reference measuring systems

Abstract

Main textIn 2016 the Consultative Committee for Electricity and Magnetism (CCEM) commissioned a supplementary comparison EURAMET.EM-S42 of Lightning Impulse (LI) measurement systems. This comparison was piloted by RISE (Sweden, formerly SP), and it was supported by VTT MIKES (Finland) and FFII LCOE (Spain). Eleven National Metrology Institutes (NMI) and two Designated Institutes (DI) from four Regional Metrology Organizations, EURAMET, COOMET, APMP and SIM, took part in the comparison.A commercial travelling measuring system (TRMS) for Lightning Impulse (LI) measurement was adopted for the comparison. The TRMS consisted of a 700 kV resistive voltage divider and a transient recorder with computer. The TRMS was calibrated by the pilot lab in November 2016 before start of the comparison, and the first circulation was between five EURAMET NMI/DIs. After an intermediate calibration by the pilot lab in July 2017, the TRMS was circulated between seven NMI/DIs in the other regional organisations. On the return of the TRMS in March 2019 a final calibration was made by the pilot lab.The measured parameters are defined in IEC60060-1. Test voltage value (U t), front time (T 1), time to half value (T 2) and relative overshoot (β') were measured for full impulses; and extreme value (U e) and time to chopping (T c) for front chopped waveform. The test voltage value ranged from -700 kV to 700 kV with two full and one chopped impulse waveform. A set of preferred voltage levels and waveforms was defined. The obtained expanded uncertainties (k = 2) of the comparison reference values (CRV) were: <0.3% for U t, <1.3% for T 1, <1.0% for T 2, <0.4% for β', <0.6% for U e and <1.4% for T c.The transfer reference measuring system of the previous LI comparison (EU-SMT4-CT98-2270), arranged between 1999 and 2002, is linked to this comparison. The link is established by comparing VTT MIKES system used 20 years ago with that used in this comparison.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 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).