Abstract
In the last decade, increasing attention has been paid to ELF (Extremely Low Frequency) electromagnetic environments in work areas as well as in and near homes, regarding their interaction both with electric apparatus such as CRT's and with biological systems. This contribution presents experimental and theoretical analysis of 60Hz magnetic field (B-field) characteristics at and near ground level in both 187/66kV EHV and 66/6.6kV HV power substations. Experimental results of B-filed profiles along horizontal paths as well as harmonic contents in B-field waveforms at several positions are shown and discussed. Furthermore, analytical B-field profiles calculated by using a B-field approximation method based on Biot-Savart law are shown and compared with the measured ones. The comparisons verify that the assumptions employed are applicable to the substation B-field calculation, and that the B-field calculation method employed can estimate the B-field in EHV and HV power substations to significant accuracy, except for areas where localized B-field sources such as power transformers and underground power cables exist. The analytical profiles of three orthogonal components of the B-field are also described in terms of equi-flux contour maps, which show 3-dimensional characteristics of the B-field in power substations.
