Interlaboratory comparisons of laboratories for calibration of active electrical energy meters

Electrical energy meters are designed for measuring, recording, and monitoring of the consumption of electrical energy in residential, commercial, and industrial premises. Working measurement standards of the unit of active electrical energy are used for verification of energy meters, which are in turn subject to regular calibration. Working measurement standards are calibrated by calibration laboratories (CLs). Interlaboratory comparisons (ILCs) for calibration of measuring instruments are essential to ensure the accuracy, reliability, and reproducibility of measurement results across laboratories. The results of these comparisons in terms of a specific calibration constitute important evidence for national accreditation bodies. Two CLs participated in an ILC for calibration of the active energy meter: SE “UKRMETRTESTSTANDARD” – UMTS, Ukraine, and ELGAMA-ELEKTRONIKA, Lithuania. The participating laboratories performed measurements of active electrical energy at an alternating current of 230 V at a frequency of 50 Hz at calibration points from 0.05 to 10 A at power factors of ±1 and ±0.5 Lag. The energy measurements of both CLs can be traced back to CLs in Germany. The results of the ILC of energy measurement standards demonstrated a satisfactory consistency of the obtained calibration results. The laboratories meet the established requirements for the En value (UMTS – from 0.02 to 0.20; ELGAMA – from 0.02 to 0.19) and have confirmed their technical competence. The UMTS is accredited by the National Accreditation Agency of Ukraine (NAAU), and the ELGAMA is accredited by the National Accreditation Bureau of Lithuania (LNAB). Both NAAU and LNAB are among the participants of the ILAC Mutual Recognition Arrangement (ILAC MRA). Both CLs meet the requirements of the international standard ISO/IEC 17025. All this contributes to the recognition of calibration results of the laboratories in their scope of accreditation, both at the national and international levels.