National Institute of Technology, Kagawa College, 355 Chokushi-cho, Takamatsu, Kagawa 761-8058, Japan.
University of Miyazaki, Japan.
Biomed Phys Eng Express. 2020 Jul 28;6(5):055012. doi: 10.1088/2057-1976/aba636.
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.
据报道，当一个接地的人处于工频电场中时，从脚流向地面的短路电流与他或她的身高的平方成正比。然而，即使身高相同，电流也应该随身体表面积（即体型）而变化。在本研究中，我们使用从半椭圆模型得出的解析解证实了这一假设。为各种数值人体模型计算了短路电流，其中体素的水平长度从 1.8 毫米变化到 3.0 毫米，比较了不同体型的结果。最后，我们从解析解中推导出了一个从人体的左右宽度（2b）、正面厚度（2c）和高度（a）估算短路电流的近似表达式。从近似表达式得到的短路电流与从 48 种不同体型人体模型的数值计算结果一致，相关系数为 0.9942。因此，我们得出结论，短路电流可以根据人体的相似比（a/b）和椭圆率（c/b）以及高度来确定。这一发现与之前使用的数值人体模型一致，其中相似比和椭圆率非常接近。因此，我们可以得出有限的结论，即短路电流仅与身高的平方成正比。此外，数值计算表明，无论一只脚还是两只脚接地，短路电流都是相同的。
