Resistance to ground of body on non homogeneous soil

摘要

To reduce touch voltage and step voltage in the case of a fault in HV systems, one of the following methods is generally used: the installation of additional earth electrodes to provide potential grading on the ground surface or the soil insulation by means of a high resistance layer. The protective method using the insulating layer reduces the touch and step voltages depending on the resistivity of the layer and on the resistivity of the soil. This paper concerns with the evaluation of the resistance to earth of body (REB) for different insulating layer placed on homogeneous and non-homogeneous ground. The calculation of the RB and the evaluation of the voltage on the surface of the earth have been carried out with analytical methods and with experimental tests on a scale model. Other experimental measures have been carried out to determinate the resistivity of different insulating layers as asphalt, rock, concrete etc.