Quantification of ELF electric and magnetic fields in residential areas.

本研究的目的是为了量化居民区极低频（ELF）电场和磁场的特性。（1）采用EMDEX MATE和EMDEX II两种非均匀磁场测量仪，研究了志愿者腰部和胸部的非均匀磁场特征。使用实验室制作的三维亥姆霍兹型线圈校准仪表。实测数据表明，在远离输电线路的居民区，我们通常暴露在非均匀磁场中。获得了个人暴露于磁场的数据，并与美国人的数据进行了比较。(2)利用模拟数据光链路测量了坐在视频显示终端前的人体内的感应电流。测量了几种电器对人体的泄漏电流，并与VDT的感应电流进行了比较。(3)在配电线路磁场波形中发现了谐波。通过对垂直、水平和三角形配电线路上流过60Hz和5次谐波电流的情况进行数值计算，研究了谐波和三相不平衡电流对磁场特性的影响。(4)研究发现，输电线路下的地面电场不仅受附近导电物体的影响，还受地面湿度的影响。(5)考虑电场和磁场的相位差，对人体模型同时暴露在电场和磁场中的感应电流进行了估计。

This research was performed in order to quantify the characteristics of extremely low frequency (ELF) electric and magnetic fields in residential areas. The following results are obtained through the research :(1) Two meters (EMDEX MATE and EMDEX II) were used in this research to find the characteristics of non-uniform magnetic fields to which the waist and the breast of a volunteer were exposed. The meters were calibrated using the laboratory-made three-dimensional helmholz-type coil. The measured data have shown that we usually are exposed to non-uniform magnetic fields in residential areas remote from power transmission lines. The data on personal exposure to magnetic fields has been obtained and compared with the data of American people.(2) The induced currents in a human body sitting in front of a video display terminal have been measured using an analog data optical link. The leakage currents from a number of electric appliances to a human body have been measured and compared with the induced currents from a VDT.(3) The harmonics were found in the waveforms of magnetic fields from a distribution line. The effects of harmonics and unbalanced three-phase currents on magnetic fields characteristics have been examined by numerical calculations performed under the condition that 60Hz and 5th harmonic electric currents flow on vertical, horizontal or delta-type distribution lines.(4) It was found that ground-level electric fields under a transmission line were affected not only by the existence of nearby conducting objects but also by the moisture of the ground.(5) The induced currents have been estimated for a human model simultaneously exposed to electric and magnetic fields in consideration of the phase difference of the two fields.