Analytical Calculation of Electric and Magnetic Fields Near a Proposed 132kV Line with Constrained Right of Way - Kenyan Case Study

Abstract

A 6.5km 132kV overhead line is proposed to link a Bulk supply substation with a proposed 132/33kV,2×45MVA substation in a coastal island city in Kenya. The proposed line is to be constructed in steel monopoles and will have 33kV overhead lines below the 132kV single circuit line. The recommended right of way (wayleave) for 132kV single circuit line is 30m as per Kenya Power and Lighting Company (KPLC) standards. However, since this particular line passes through highly constructed area in a city, the available right of way was constrained to 10m i.e, 5m on each side measured from the center of the line. From site survey, 3 specific points of interest were also identified where already constructed storey buildings were found just beyond the edge of the right of way. The objective of this paper is to do analytical calculations of the electric and magnetic fields anticipated to be experienced at 1m above the ground at the edge of the 10m right of way of the proposed 132kV line, as well as at the top of the storey buildings at the specific points of interest identified during site visit. The calculations were done using the parameters of the already proposed steel monopoles whose heights had been determined based on terrain and clearance requirements only. Since the electric field values obtained were found to be beyond the recommended limits by International Commission on Non Ionizing Radiation Protection (ICNIRP) 2010 guidelines, recommendations on mitigation measures to ensure compliance are proposed and recalculations were carried out to demonstrate adequacy of the recommendations to ensure compliance.