Abstract:In the ICNIRP guidelines on the protection of human exposure to low frequency electric and magnetic fields, the reference levels are given based on the maximum value of induced electric fields (EF’s) inside a numerical human model that stands erect on ground plane with both hands down by its sides. In this contribution, numerical results on the induced EF’s inside a numerical human model standing with elevated arms in a 50 Hz uniform EF, are illustrated. The effect of the arm elevation angle on the maximum EF … Show more
It has been reported that when a grounded human is exposed to an electric field at power frequency, a short-circuit current flowing from the feet to the ground is proportional to the square of his or her height. The current, however, should also vary with the body surface area, that is, body shape, even in people with the same height. In the present study, we confirmed this hypothesis using an analytical solution derived from a semi-ellipsoidal model. The short-circuit currents were calculated for various numerical human body models in which the horizontal length of a voxel was varied from 1.8 to 3.0 mm, and the results for different body shapes were compared. Finally, we derived an approximate expression for estimating the short-circuit current from the left-right width (2b), frontal thickness (2c), and height (a) of a human from the analytical solution. The short-circuit currents obtained from the approximate expression are consistent with those obtained from numerical calculations for 48 differently shaped human body models with a correlation coefficient of 0.9942. Hence, we concluded that the short-circuit current can be determined depending on the similarity ratio (a/b) and the ellipticity ratio (c/b) of the human body as well as the height. This finding is consistent with the numerical human body models that have been used previously, in which the similarity and ellipticity ratios were very close. Therefore, we can make the limited conclusion that the short-circuit current is proportional only to the square of the height. Additionally, numerical calculations showed that the short-circuit current is the same whether one foot or both feet are grounded.
It has been reported that when a grounded human is exposed to an electric field at power frequency, a short-circuit current flowing from the feet to the ground is proportional to the square of his or her height. The current, however, should also vary with the body surface area, that is, body shape, even in people with the same height. In the present study, we confirmed this hypothesis using an analytical solution derived from a semi-ellipsoidal model. The short-circuit currents were calculated for various numerical human body models in which the horizontal length of a voxel was varied from 1.8 to 3.0 mm, and the results for different body shapes were compared. Finally, we derived an approximate expression for estimating the short-circuit current from the left-right width (2b), frontal thickness (2c), and height (a) of a human from the analytical solution. The short-circuit currents obtained from the approximate expression are consistent with those obtained from numerical calculations for 48 differently shaped human body models with a correlation coefficient of 0.9942. Hence, we concluded that the short-circuit current can be determined depending on the similarity ratio (a/b) and the ellipticity ratio (c/b) of the human body as well as the height. This finding is consistent with the numerical human body models that have been used previously, in which the similarity and ellipticity ratios were very close. Therefore, we can make the limited conclusion that the short-circuit current is proportional only to the square of the height. Additionally, numerical calculations showed that the short-circuit current is the same whether one foot or both feet are grounded.
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