BS IEC 61786-2:2014:2015 Edition

IEC 61786-2:2014 provides requirements for the measurement of quasi-static magnetic and electric fields that have a frequency content in the range 1 Hz to 100 kHz, and DC magnetic fields, to evaluate the exposure levels of the human body to these fields. Specifically, this standard gives requirements for establishing measurement procedures that achieve defined goals pertaining to human exposure. Because of differences in the characteristics of the fields from sources in the various environments, e.g. frequency content, temporal and spatial variations, polarization, and magnitude, and differences in the goals of the measurements, the specific measurement procedures will be different in the various environments. Sources of fields include devices that operate at power frequencies and produce power frequency and power-frequency harmonic fields, as well as devices that produce fields independent of the power frequency, and DC power transmission, and the geomagnetic field. The magnitude ranges covered by this standard are 0,1 micro-Tesla to 200 mili-Tesla for AC (1 micro-Tesla to 10 Tesla for DC) for magnetic fields, and 1 V/m to 50 kV/m for electric fields. When measurements outside this range are performed, most of the provisions of this standard will still apply, but special attention should be paid to the specified uncertainty and calibration procedures. Examples of sources of fields that can be measured with this standard include: – devices that operate at power frequencies (50/60 Hz) and produce power frequency and power-frequency harmonic fields (examples: power lines, electric appliances…); – devices that produce fields that are independent of the power frequency.(Examples: electric railway (DC to 20 kHz); – commercial aeroplanes (400 Hz), induction heaters (up to 100 kHz), and electric vehicles); – and devices that produces static magnetic fields: MRI, DC power lines, DC welding, electrolysis, magnets, electric furnaces, etc. DC currents are often generated by converters, which also create AC components (power frequency harmonics), which should be assessed. When EMF products standards are available, these products standards should be used. With regard to electric field measurements, this standard considers only the measurement of the unperturbed electric field strength at a point in space (i.e. the electric field prior to the introduction of the field meter and operator) or on conducting surfaces. Sources of uncertainty during measurements are also identified and guidance is provided on how they should be combined to determine total measurement uncertainty.

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