Magnetic field from spot welding equipment—is the basic restriction exceeded?

Abstract

A point measurement of the magnetic field (MF) near a typical spot welding machine showed that the magnetic flux density was above the ICNIRP reference level. To investigate if the basic restrictions were exceeded, the induced body currents in a full 3D human model were calculated. It was found that at an operator position of 34 cm away from the machine the maximum induced current density was below the ICNIRP basic restriction. But if the operator was closer to the machine, the basic restriction was exceeded. An important finding of the present article is that the basic restriction can be exceeded although the MF spatially averaged over the whole body is well below the reference level.

Comparison of SAR and induced current densities in adults and children exposed to electromagnetic fields from electronic article surveillance devices

“…Their results for the adult model were lower than the ICNIRP safety guideline, but could approach or even exceed the ICNIRP basic restrictions for models of 10-and 5-year-old children if sufficiently strong magnetic fields were used. The 3D impedance method used by Gandhi and Kang in the above-mentioned paper has been also used by other authors for analysing human exposure to EAS devices operating at frequencies from hundreds of Hz to 30 kHz (Nadeem et al 2003). For exposures to higher frequencies (i.e.…”

“…(Kang and Gandhi 2003), carrying in-phase currents of 4 A turns rms. Although several authors use higher currents (100 A are used in Gandhi and Kang (2001) while 142 A are used inNadeem et al (2003)), 4 A is chosen here in order to reproduce the actual measurements of magnetic flux density reported byTrulsson et al 2007. Results are easily scaled, since the magnetic fields are linear to the magnitudes of the driving currents.…”

Development of the female voxel phantom, NAOMI, and its application to calculations of induced current densities and electric fields from applied low frequency magnetic and electric fields

“…This is a geometric effect due to the brain for the shorter models being in considerably higher nonuniform fields from the particular device than the brain of the taller adult. Other examples of application to non-uniform fields can be found in Dawson et al (1999) where they considered realistic postures and configurations of three-phase current carrying conductors and Nadeem et al (2004) who investigated magnetic fields from spot welding equipment. A quasistatic finite-difference method has also been used to study the induced electric fields in the human body for magnetic stimulation by gradient coils (Liu et al 2003a) and from motion in high static magnetic fields (Liu et al 2003b) in MRI.…”

Effects of skeletal muscle anisotropy on induced currents from low-frequency magnetic fields

“…In order to calculate the induced currents, the impedance method is used implementing the formulation described in Nadeem et al (2004). The application of the method requires the anatomical model to be represented by an equivalent 3D resistance network (figure 2).…”