Upon the Influence of Charge Image on the Electric Field Intensity

The paper is dedicated to studying the contribution of underground image of overhead power lines to the actual electric field strength at a certain point of interest in their immediate vicinity. More precisely, it is about the image of an electric charge; accordingly, an analytical method is developed, allowing as the linear charge density to be calculated based on the effective (r. m. s.) phase voltage and also, the calculation of the electrical potential at the surface of the live conductor. The analytical results were the basis for the validation of some simulations performed with CST Studio and EMFACDC for various power line configurations. An application has been developed to study the influence of soil conductivity and permittivity, the results being compared with the (theoretically) extremes: perfectly conductive and perfect insulator cases. The results showed an increase of about 65% of the electric field strength in wet soil, relative to dry soil. This conclusion is an argument that nuances the rather widespread, superficial approach that, from the point of view of the formation and the influence of electrical charge image in the soil, any soil is a perfect conductor. Finally, a number of achievable recommendations are done, aiming on reducing the exposure to electric fields generated by overhead high-voltage power lines (OhHVPLs).