Electric Field in the Vicinity of High Voltage Deviation Towers

Abstract

There is a general concern about the impact that high voltage overhead power lines have on the environment, from the most diverse perspectives and points of view. One of the essential items to be addressed and resolved properly is the associated electric and magnetic fields, measured by convention, at a height of 1 m from the ground. Regarding strictly the generated electric fields, in the vast majority of cases, the registered values are below the limit of 5 kV/m, considered acceptable by the standards and norms in force. In this paper we have focused on the simulation of electric fields generated near a deviation tower, inside the angle having the tower itself as tip and the two alignments as sides. We have developed for our purpose a programming within the CST studio, a very powerful software much more used in the simulation of the radio frequency electromagnetic phenomena than of the extremely low frequency ones (the case of mains frequency). As a criterion for comparing the electric field emissions around a deviation tower, respectively a suspension tower, we used the current density induced along the vertical axis of a 3D human model previously proposed by the authors, also developed in CST Studio. Increases in the induced current density have been found, due to the summative-cumulative effects imposed by the angular configuration, both sides of the angle contributing to the induced current. Relative increases of over 50% have been found. However, these increases are offset by the height of the conductors. In the vicinity of the pylon the height is higher than in the middle of the distance between two consecutive towers, where the sag can reach values of 12 m. Another cause that contributes to attenuating the cumulative effects generated by the angled structure is the relative position of insulating chains. At deviation towers, they have an oblique position, raising the conductors higher from the ground than in the case of the suspension towers, where the position of the insulators is vertical. The simulated results show that human exposure in the area to electric fields near deviation towers is 30-40% higher than exposure in the area of a suspension tower but is perfectly comparable to human exposure in the middle of the distance between two consecutive towers, where sag reaches its maximum.