Análise dos riscos de fibrilação ventricular devido à tensão induzida por descargas atmosféricas em cercas próximas à linhas de distribuição

Abstract

In rural areas, fences are exposed to dangerous voltages when built close to transmission lines. To minimize risks, grounding and sectioning criteria are established in ABNT and/or company norms. However, such norms aim at the sinusoidal steady state of transmission lines. Nonetheless, fences are also exposed to transient phenomena such as lightning which, in addition to inducing voltages in the conductors of the fence, can cause dangerous step and touch voltages for people and animals. This work proposes to analyze the step and touch voltages in a system where a fence, built near a transmission line, is exposed to electromagnetic fields induced by lightning and by the magnetic coupling between the line and the fence. The main objective is to evaluate the risks of ventricular fibrillation to which an individual, located in the vicinity or in contact with the fence, may be exposed during the occurrence of the phenomenon. In the simulations, the influence of the variation in the distance between the fence and the net, soil resistivity and the position of the individual was analyzed. Through this study, we can conclude that the preponderant factors for the survival of the individual are the resistivity of the soil and the position of the individual in the line-fence system. However, most of the results must be carried out with caution, given that the effects of the current conducted through the ground, variation of the atmospheric discharge parameters such as peak value of the current and potential rise due to the injection of current into the ground by the atmospheric discharge itself were neglected.