Compliance of non-sinusoidal or pulsed magnetic fields generated by industrial sources with reference to human exposure guidelines

In this paper theory and methodology to analyze non-sinusoidal/pulsed fields created by industrial sources in the low frequency range are presented. The methodologies to analyze non-sinusoidal fields are introduced by recalling the fundamental electrostimulation mechanisms. Finally, a case study of a resistance spot welding gun is considered and the results are discussed. Regarding the resolution of the human model, it is found that using a 1 x 1 x 1 mm(3) discretization and then apply a spatial averaging in a volume of 2 x 2 x 2 mm3 is almost equivalent to the direct use of a resolution equal to 2 x 2 x 2 mm(3). Furthermore, several metrics to remove numerical artifacts are also tested. Some of them are based on the percentile filtering whereas others are based on a statistical procedure aimed to filter out the outliers in the numerical solution. It is pointed out that, for a localized exposure, the statistically based approaches goes in the direction to define a metric able to adapt to each specific exposure condition, the 99th percentile can underestimate the actual maximum that, on the contrary, it is better estimated by the 99.9th percentile.