Analysis of Magnetic Field Exposure at Extremely Low Frequency (ELF) in 330kV Transmission Switchyards

Abstract

The present study assessed the exposure levels of extremely low frequency (ELF) magnetic fields in five 330 kV transmission switchyard of generation stations located in north-central, Nigeria. In conformity with IEEE standards of measurement procedures, ELF magnetic field levels were detected in the switchyards using Extech 480826 triple-axis EMF metre via spot technique at three different observation heights of 1.0, 1.5 and 1.8 m. The data obtained were subjected to analysis using the One-way ANOVA SPSS package. The results demonstrated occupational significant differences of (p < .001) between 330 kV switchyards of Shiroro Hydro-plant and Geregu Phase II Gas-plant, significant differences of (p = .045) between switchyards of Geregu Phase I Gas-plant and Geregu Phase II Gas-plant, and also significant differences of (p < .001) in occupational exposure was demonstrated between switchyards of Jebba Hydro-plant, Kainji Hydro-plant when separately compared to Geregu Phase I and Geregu Phase II Gasplants. However, non-significant differences occurred between switchyards of Shiroro Hydro-plant and Jebba Hydro-plant, Kainji Hydro-plant and Geregu Phase I Gas-plant, and Jebba Hydro-plant with Kainji Hydro-plant. This study has revealed the occurrence of field pollution within the switchyard and the variation of ELF magnetic field magnitude from between switchyards