Studying Direct Lightning Strike Impact on Human Safety Near HVTL Towers Considering Two Layer Soils and Ionization Influence

Abstract

This chapter contains the following points: design procedure of grounding system according to IEEE 80, methods for calculating the grounding grid resistance (Dwight's formula, Laurent and Niemann, Sverak's equation, Schwarz's formula, Dawalibi, Mukhedkar's formula, Chow and Salama's formula, Nahman's formula, and Heppe's method). It contains also the design of charts of grid earthing system and application of step and mesh potential in safe grounding system design. There are two main design goals to be achieved by any substation ground system under normal as well as fault conditions. These are 1) to provide means to dissipate electric currents into the earth without exceeding any operating and equipment limits and 2) to assure that a person in the vicinity of grounded facilities is not exposed to the danger of critical electric shock. The design procedures described in the following sections are aimed at achieving safety from dangerous step and touch voltages within a substation. It is possible for transferred potential to exceed the GPR of the substation during fault conditions.