Estudio del comportamiento ante descargas tipo rayo de los sistemas de puesta a tierra en líneas aéreas de electricidad, mediante el Software ATP-DRAW

Abstract

Overhead electricity transmission lines are exposed to atmospheric discharges, in some cases protected by guard wires, as is the case of sub-transmission lines (69 kV) and transmission lines (138 kV, 230 kV, 500 kV), while distribution lines (13.8 kV) for the most part do not require a guard wire, due to its low height with respect to the ground (around 10 meters), except for those places with open skies (there are no buildings, nor vegetation that exceeds 10 meters in height). In the case of lines that incorporate guard wire, atmospheric currents, either by direct impact or induction, must be discharged to earth, which generate a potential on the grounding system with the consequent step and contact voltages to which mainly human beings are exposed. In the case of distribution lines, the atmospheric phenomenon is mostly reflected in the induction of voltages due to the effects of lightning strikes near the lines, producing in some cases direct fluttering and in others inverse fluttering in the insulators, which also produces a discharge of current to earth. In this research we present the behavior of the most commonly used grounding systems for distribution structures (vertical electrode with and without embedded, horizontal electrode, in-line electrodes). For subtransmission, in addition to the previous ones, we present arrangements such as circular ring and square ring with spades at the vertices. Finally, for tower-type structures (subtransmission and transmission), counterweight or counter-antenna type arrays.