Set Up and Characterization of a System for the Generation of Reference Magnetic Fields From 1 to 100 kHz (original) (raw)
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Setup for Generating an AC Magnetic Field From 3 to 100 kHz
IEEE Transactions on Magnetics, 2015
Generating a stable, homogeneous reference ac magnetic field is important for traceable calibrations of ac magnetic field analyzers with a triaxial coil probe (e.g., EFA 300, C.A. 42). These probes are widely used by health and safety professionals, in manufacturing, and in service industries. This paper presents a single-layer Helmholtz-type solenoid for generating the reference ac magnetic field in the frequency range from 3 to 100 kHz. Special attention is given to a full characterization of this setup, including a comparison between the analytical and finite element method design of the solenoid, on the one hand, and experimental results, on the other. The magnetic flux density inside the solenoid can be generated with expanded uncertainty of (0.4%-0.8 %) for k = 2 using a special search coil.
IEEE Transactions on Instrumentation and Measurement, 2013
The aim of this paper is to describe a procedure and experimental setup for calibration of AC induction magnetometer. The paper presents an overview of the previous research and results of measurement of magnetic flux density inside largediameter multilayer solenoid. This solenoid is magnetising coil of the magnetometer. The paper also describes a system of five smaller coils of the magnetometer which are placed inside the large solenoid. Three small coils are pickup coils, accompanied with two compensation coils, of which one is an empty coil for magnetic field measurement. The experimental results of calibration of this coil system have been presented. A proper discussion of all the results presented has been also given in the paper.
Calibration of magnetic field probes at relevant magnitudes
2013 19th IEEE Pulsed Power Conference (PPC), 2013
Difficulty driving large currents through an inductive load at high frequency typically results in field magnitudes of a few microTesla or less. The calibration factor is then necessarily assumed linear, even though the magnetic field of the primary experiment is several orders of magnitude larger than the field magnitude used to calibrate the probe. In this work calibration factors of two differential configuration magnetic field probes are presented as functions of frequency and field magnitude. Calibration factors are determined experimentally using a 80.4 mm radius Helmholtz coil in two separate configurations.
Generating an AC amplitude magnetic flux density value up to 150 μT at a frequency up to 100 kHz
Journal of Electrical Engineering, 2017
AC magnetic field analyzers with a triaxial coil probe are widely used by health and safety professionals, in manufacturing, and in service industries. For traceable calibration of these analyzers, it is important to be able to generate a stable, homogeneous reference AC magnetic flux density (MFD). In this paper, the generating of AC amplitude MFD value of 150
The Use of Helmholtz Coils Designed for 50 Hz at Higher Frequencies
Annals of the University of Craiova, Electrical Engineering series, No. 44, Issue 1, 2020; ISSN 1842-4805, 2020
Helmholtz coils (HC) are used in order to generate and control uniform magnetic fields for a variety of research applications. They can be easily constructed and their fields can be easily calculated. This makes them especially useful in calibrating magnetic field sensors. Such a calibration system with large Helmholtz coils (1x1m) can be found in ICMET Institute, designed to operate only at a frequency of 50 Hz. There has recently been a request for the calibration of several measuring sensors operating at frequencies up to 10 kHz used in industrial applications such as induction hardening of metal parts. The paper aims to determine the conditions under which this low frequency HC system can be used at frequencies at least 100 times higher. The first part of the paper describes a theoretical analysis on the volume confining the space where the magnetic field components have a predetermined deviation (a 2% threshold) from the center of the HC system followed by a comparison with a 3D FEM simulation and measurement of HC field. The second part describes the identification of the HC parameters at higher frequencies and the resonant methods used to achieve the excitation power required at these frequencies.
A reference system for the measurement of low-strength magnetic flux density
Journal of Magnetism and Magnetic Materials, 2006
Magnetic flux density standards traceable to the SI units have been developed at IEN-INRIM, by which dissemination for general measurement and testing activities can be pursued. The reference system covers a range of values extending from m 0 H$1 T to m 0 H$10 mT and is centered on the use of NMR magnetometers, calibrated coils, and stable current sources. The relative measuring uncertainty of the system is shown to increases with decreasing the field strength value and it is estimated to range between a few 10 À6 and some 10 À3 .
Performance of low frequency magnetic field meters to sinusoidal and beat-phenomenon magnetic fields
Measurement, 2006
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 environments. 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 fundamental frequency, and waveforms having beat phenomena. The results of the study show a lack of accuracy of some magnetometers 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.
This paper proposes a simple semi-analytical method for designing coil-systems for homogeneous magnetostatic field generation. The homogeneity of the magnetic field and the average magnitude of the magnetic flux density inside of the volume of interest are the objective functions chosen for the selection of the coil-system geometry (size and location), number of coils and the number of turns of each winding. The spatial distribution of the magnetostatic field is estimated superposing the magnetic induction numerically computed from the analytical expression of the magnetic field generated by each coil, obtained using the Biot-Savart's law and the current filament method. The homogeneous magnetic field is synthesized using an iterative algorithm based on TABU search with geometric constraints, which varies the design parameters of the windings to meet the requirements. The number of turns of each coil and gauge of wire used for the windings is adjusted automatically in order to achieve the target average magnitude of the magnetic induction under the constraints imposed by power consumption. This method was used to design a coil arrangement that can generate up to 10 mT within a volume 0.5 m×0.5 m×1 m with 99% of spatial homogeneity, with square loops of length less than or equal to 1.5 m, and with a power dissipated by Joule effect less than or equal to 1 W per coil. The synthesized magnetic field distribution was validated using Finite Element Method simulation, showing a good correspondence between the objective values and the simulated fields. This method is an alternative to design magnetic field exposure systems over large volumes such as those used in bioelectromagnetics applications.
2015
Introduction: The aim of this research was to build a variable magnetic field system that can be used in many medical fields such as medical physics, physiology, genetics, biochemistry, anatomy, etc. Materials and methods: In this experimental study the magnetic field was produced between Helmholtz coils by using a variable power supply and signal generator systems. The user can select the desired frequency between 0 Hz (as a static magnetic field) to 300 Hz (as a pulsating magnetic field) with the selector generator. This square wave signal produces magnetic field with intensities from 0 to 8 mT with variations in current. Results: This generator was designed with Helholtz coils which can produce nearly uniform magnetic fields with different frequencies and intensities. This system can simulate fields that general population are subjected to and are concerned about. Conclusion: Calibration with a Hall probe, proved the proper production of a uniform magnetic field of desired intens...