Bilateral comparison of AC power measurements

Project Description

A bilateral comparison complementing EUROMET 385 is carried out between Denmark and Romania. The transfer device used is a one-phase precision energy standard Landis+Gyr TVL 3.1. The measurement points are chosen to co-incide with those of EUROMET 385 and CCEM K5, expect for measurement points with power factor 0. Instead measurements are performed at power factor 0,2. In addition, measurement points corresponding to those of standard verification of electrical energy meters are to be measured. Daniamet-Arepa is a participant of EUROMET 385 and will act as pilot laboratory for the bilateral comparison and provide linking values. DFM will act as coordinator and prepare the measurement protocol, as well as draft and final reports.

Final Report 2004-02-04

A bilateral pilot comparison complementing EUROMET 385 was carried out between Denmark and Romania in the period August 2003 to October 2003
The transfer device used was a one-phase precision energy standard Landis+Gyr TVL 3.1. The measurement points were chosen to co-incide with those of EUROMET 385 and CCEM K5, expect for measurement points with power factor 0. Instead measurements are performed at power factor 0,2. In addition, measurement points corresponding to those of standard verification of electrical energy meters were measured. A total of 13 points were measured. The measurand was the relative error of the value derived from the generated pulse train.
The measurement results were reported in measurement reports by the participants. The uncertainties reported were in the rage 0,002%–0,017%. Daniamet-Arepa, measured the device before and after measurements at INM, and from the difference between the initial and final measurements it is assessed that the transfer device did not exhibit excessive drift. Therefore no correction for such effect has been made. From the standard deviation of the differences between the initial and final measurements at the pilot laboratory of each measurement point, the stability of the transfer device is estimated as uS = 0,0020 %.
After distribution of the draft report, Daniamet-Arepa reported a calculation error in the determination of the results for measurement point with power factor different from 1, and a reporting error in the uncertainties for the same measurement points.
The normalised difference, EN, between the results of the two laboratories was calculated and generally good agreement was found. However, for four measurement points, EN values larger than one was found (1,1–1,7) and an overall bias of about 0,01% is indicated from a weighted average of the difference between the results of the two laboratories.
The source of disagreement has not been uncovered at this time.
A full report on the comparison is available from the coordinator: reference DFM-03-R63.