In Germany for example the regulation BGV B11 has to be applied. The safe operation of demagnetizers requires the observance of exposure limits!. Workplaces must be checked for compliance with the regulations of the employers’ liability insurance associations BGV B The measurements or calculations. Health and Safety Regulation on electromagnetic fields (EMFV); The health and safety requirements of the employers’ liability insurance association BGV B

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Electromagnetic environmental compatibility

The weighting filter W f must have the inverse frequency response of and is therefore given by:. The best thing is to use WPM exclusively in the time domain, as additional potential errors due to cyclical convolution cannot occur.

Quite the opposite is the case. The weighting filter convolves the field quantity g t with an impulse response w twhere w t is the inverse Fourier transform of W f:. The acronym pwl stands for piecewise linear. Check of combustion conditions. The eigenvector with the highest eigenvalue indicates the direction of an optimally aligned single axis probe.

All modern measurement systems sample and digitize either g t or s t using an AD converter. In particular, WPM in the time domain can be used without a second thought.

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German Sustainable Building Council auditor. Inconsistency of a recently proposed method for assessing magnetic field exposure for protection against peripheral nerve stimulation in occupational situations.

The integration time of 1 s for the ostensibly relevant RMS value formation is claimed to be based on fiber-dependent physiological data in the range from ms to a few seconds.

Some technical aspects of real measurement systems are also examined. Open in a separate window. This is because the permissible field quantity swing has been set too high by a factor of 2. For this reason, very high order FIR filters can be realized at acceptable cost, so that filters with sharp edges can at least be very closely approximated.


Residential Buildings and Hotels. The electric field strength e t within the body determines the stimulation effect.

This is allowed until V equals V max. All currently available measurement systems sample either g t or s t. Nevertheless, only very short and very long impulses can be evaluated exactly. Emulation of the sharp edges of R f should not therefore be pursued because artifacts occur that lead to erroneous estimation of the exposure index.

If measurements cannot be performed e. How this works can be seen clearly from the example of a pulsed and sinusoidal signal: For a start, all three variants of the filter would have to be of infinitely high order and are therefore unrealizable as such. These relationships are already described correctly in the literature Rueckerl and Eichhorn If g t actually consists only of segments that correspond exactly to these four curve forms, BGM can be used.

Thermal and moisture protection. Shaped time domain method. Because the phase of the spectral components is not taken into account in this simple approach and the worst case with a phase of 0 for all components is assumed, this often leads to a clear overestimation of exposure but never to an underestimation.

Schmid G, Hirtl R. Hazardous substances in the workplace.

Reverberation room echo room. So at low frequencies, it is sufficient and necessary to limit the maximum value bbv the slope only. Values of less than unity are permissible. In contrast, filters that can be formed from a cascade of first order filter elements emulate the underlying effects much more realistically.


Electromagnetic environmental compatibility – Müller-BBM GmbH

The weighting filter convolves the field quantity g t with an impulse response w twhere w t is the inverse Fourier transform of W bv Frequency-dependent reference levels R f are used to specify the permitted exposure of persons to external electromagnetic fields. The second method initially determines the spectrum G f of g t by applying the Fourier transformation. It is intricately worded and can only be used by experts who have studied it in detail.

Despite this, a significant overestimation cannot be excluded either. Thus, the usual W f that emulates the underlying physical and biological effects accurately, and can be realized using first order filter elements, is not always used. It also does not emulate the unnecessary overestimations at bg frequencies and linear field changes or the negative effects of the unrealistic piecewise linear reference curves. It is worth knowing that EI noise also increases proportionally to the square root of the measurement system bandwidth.

The peak value of the weighted time signal s t is determined in a second step. The condition for this to be true and for DFT to be applicable bv WPM is that the ggv T w of the impulse response w t is less than T byv otherwise, w t cannot be reproduced without errors.

The time signal g t is equal to 0 outside the period T.