General Public Exposure by ELF Fields of 150–36/11-kV Substations in Urban Environment

Electromagnetic exposure of the general public due to large substations transforming voltages of 150 and 36 kV to 11 kV is investigated and safety distances for these substations have been determined. In total, 142 field measurements were executed for two substations: 91 measurements of the magnetic field and 51 measurements of the electric field. Measured momentary magnetic-field values are within the range of 0.051 to 13.17 muT. The levels of the electric field are within the range of 0.095 to 270.0 V/m. The cumulative distribution function of the measured magnetic-field values has been determined, and it is shown that the fields excellently follow a lognormal distribution. The maximal magnetic- and electric-field values for all the investigated substations are below 100 muT (values over a day and year) and 5 kV/m, respectively. When comparing the average exposure with the value of 0.4 muT, safety distances of maximally 8.1 m (average day) and 7.1 m (average year) are obtained.