Theoretical Computation of Magnetic Flux Density within the Vicinity of Rukpokwu 11 KV Distribution Power Lines

Abstract

Horizontal conductors used for distribution of electrical power generate magnetic fields around the vicinity of the conductors due to the flow of current. In the absence of a well calibrated magnetometer, theoretical estimation of the magnitude of the magnetic flux density around these power lines is possible and recommendable. In this study, we calculated the magnetic field exposure from extremely low frequency magnetic field around 11 kV power distribution lines at Rukpokwu, Rivers State, Nigeria using theoretical and mathematical formulations. 32 sample points were considered at horizontal distances of between 1 m and 1000 m from the foot of the vertical pole subtending the electrical conductors. We used a mathematical software (Wolfram Mathematica 8.0) to generate the initial results of the magnetic field current coefficients (Icoef) for the vertical and horizontal components of the magnetic fields and the total magnetic fields for x=1 to 1000 m (horizontal distance from the foot of the pole) for a vertical height of 1 m above the ground surface (considered to be the average height of head positions of the workers and the public within the vicinity of magnetic field). The results showed that for horizontal distances of between 1 and             10 m, the magnetic field exposures ranged from 45.82T/hr to 21.62T/hr and are above the occupational field exposure limit of 21.0 set by International Committee on Non Ionizing Radiation Protection (ICNRIP). Also, the results of field exposure for horizontal distances ranging from 1 to 20 m were between 45.82 and 8.3 and are above the ICNRIP limit of 4.2 set for the public. It is recommended that between horizontal distances of 1 and 10 metres from the distribution lines, relevant government agencies and the populace should discourage the building of shops for businesses, and between the horizontal distances of 1 to 20 metres, they should discourage the building of residential areas, since doing business and residing within these stipulated distances may not be very safe as a result of the magnetic field exposure.