Measurements of power frequency magnetic fields away from power lines

Abstract

Recent epidemiological studies have focused attention on the measurement of ambient level power frequency magnetic fields in residential and industrial settings. These fields can be as much as two orders of magnitude smaller than power line magnetic fields and can also contain significant levels of harmonic content. Because the existing IEEE standard for characterizing power frequency magnetic fields is intended for measurements near power lines, it has a number of inadequacies if used alone for guidance during the measurement of residential fields. This paper describes the instrumentation, calibration procedures, and outlines measurement strategies which can overcome some of the shortcomings of the existing standard. Examples of ambient level magnetic field measurements are also provided.

Performance of low frequency magnetometers to non-sinusoidal magnetic fields

“…An alternative for solving this problem is to use a measurement system consisting of a detector without an integrating stage [18]. The Table 2 Comparison of the waveform rms value and peak value measurement errors for 30% and 50% phase control waveform tests.…”

“…With this measurement approach for detecting higher order harmonics, the correct harmonic percentages and their phase relations can be determined. When the probe and the detector are close, the electrical noise can create a ''noise floor'' which prevents magnetic field measurements below a certain level [18]. The use of a reduced magnitude resolution on the display for the small amplitude harmonic components can produce large errors and the non-detection of the small amplitude components.…”

Comparison of 2D algorithms for the computation of power line electric and magnetic fields

“…Most of the published 2D algorithms for computing power line magnetic fields are based on the assumption that the power line is infinitely long [9][10][11][12][13][14]. A number of studies and measurements have been conducted that confirm the validity of these approaches [14,[18][19][20][21].…”

ELF electric and magnetic field measurement methods

“…With this approach, voltages [Eq (5)] corresponding to signals that are produced by small magnetic fields are injected into the detector circuit. Further details of this approach can be found in References [20] and [22].…”