Performance of low frequency magnetic field meters to sinusoidal and beat-phenomenon magnetic fields C.A. Cortes a, * , H. Bru ¨ ggemeyer b , R. Dib c , E. Mombello a , G. Ratta ´ a a Instituto de Energı ´a Ele ´ctrica (IEE), Universidad Nacional de San Juan, 5400 San Juan, Argentina b Niedersa ¨ chsisches Landesamt fu ¨r O ¨ kologie (NLO ¨ ), 30449 Hannover, Germany c University of Applied Sciences Giessen-Friedberg, 61169 Friedberg, Germany Received 10 December 2004; received in revised form 26 October 2005; accepted 9 December 2005 Available online 26 January 2006 Abstract This paper presents the first part of a research work dealing with the performance assessment of commercially available magnetometers. The aim of the article is to make a comparative study on the accuracy of several magnetometers used today by agencies and research institutes to measure magnetic fields produced by power systems in public and work envi- ronments. There is still a lack in the knowledge about the measurement accuracy for the complex case of having several harmonic components like those usually present in distribution networks. The frequency behavior of several commercially available magnetometers has been analyzed using a calibrated Helmholtz coil. The accuracy of 41 magnetometers has been investigated during the research by measuring sinusoidal fields in the frequency range from 10 Hz to 10 kHz, including harmonic frequencies of 50 and 60 Hz, interharmonic frequencies and signals having small deviations from the fundamen- tal frequency, and waveforms having beat phenomena. The results of the study show a lack of accuracy of some magne- tometers at frequencies above 3 kHz, large errors at the 16.66 Hz frequency used in transportation systems, and increased errors were found in the rms measurement of beat-phenomenon waveforms. The increased error in this non-sinusoidal waveform type demands a deeper research on the accuracy of magnetometers when measuring non-sinusoidal waveforms. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Magnetic field measurement; Magnetometer; Helmholtz coils; Harmonics; Interharmonics; Measurement error 1. Introduction The study of magnetic field measurements has been discussed by the scientific community for some decades. This interest has emerged due to the fol- lowing facts: • The physical complexity of magnetic fields [1]: the magnetic field vector in workplaces traces out a complicated shape over time. In the vicinity of different magnetic field sources, the magnetic field varies widely in magnitude, frequency con- tent, form of its path, and other characteristics. The measurement of these fields is difficult 0263-2241/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.measurement.2005.12.009 * Corresponding author. Tel.: +54 2644226444; fax: +54 2644210299. E-mail addresses: camilo.cortes@gmail.com (C.A. Cortes), mombello@iee.unsj.edu.ar (E. Mombello). Measurement 39 (2006) 381–392 www.elsevier.com/locate/measurement