Soil Ionization Due to High Pulse Transient Currents Leaked by Earth Electrodes

Abstract

Abstract-This paper proposes a numerical model of the soil ionization phenomena that can occur when earth electrodes are injected by high pulse transient currents, as the one associated with a direct lightning stroke. Based on finite difference time domain numerical scheme, this model ascribes the electrical breakdown in the soil to the process of discharge in the air. In fact, as soon as the local electric field overcomes the electrical strength, the air in the voids trapped among soil particles is ionized, and the current is conducted by ionized plasma paths locally grown. The dimension of these ionized air channels is strictly dependent upon the local temperature. Thus, a local heat balance is enforced in order to obtain the time variable conductivity profile of the medium. This model can be implemented both for concentrated and extended electrodes, since no hypothesis has to be enforced about the geometric shape of the ionized region. Validation of the proposed model is obtained by comparing simulation results with experimental data found in technical literature.

Lightning impulse performance of a wind generator grounding grid considering soil ionization

“…Therefore, the air gaps within the soil have highly irregular shape, especially if the surrounding pieces have sharp edges. This makes the maximum electric field inside the air voids within the soil significantly higher than the maximum electric field within the voids of an air gap having the same average size [12]. Therefore, the field enhancement in voids enclosed within the soil can be reasonably considered as the cause of the beginning of the ionization process in the soil.…”

“…Because of the structure of the soil, it is very unlikely that regular and uniform ionized zones can result. In fact most soils consist of a mixture of small and nonconductive grains, water and air [12]. The water and air fill up the vacuity among the solid pieces, forming a large and close net.…”

Piezoelectric model of rainfall energy harvester

“…Matched inductive loads and schemes, which place a capacitor before the load in the conditioning circuit [35,36], increase the electrical energy transferred to the electrical system. A more definite analysis will concern the behavior of the device in the presence of strong stresses in terms of the electromagnetic field [37][38][39], by modeling the device as a receiving antenna [40][41][42] or in advanced interconnected configurations [43].…”

Resonance on Transformers Excited by Square Waves and Explanation of the High Voltage on Tesla Transformer

“…Others analyze disks [5,6], as well transformers, where excitation is sinusoidal [7][8][9][10][11][12] or, in some cases, square waves [13,14]. Naturally, studies about excitation of circuits by square wave is generally applied to power electronics [15,16], pulse waves [17][18][19][20][21][22] or pulse transformers [23][24][25][26][27][28]. In these cases, we find in literature researches applied to Tesla transformer [29][30][31][32] where resonance phenomena are hardly described, being seen as a doubly resonant effect.…”