Search results for "Soil ionization"
showing 3 items of 3 documents
Finite difference time domain simulation of earth electrodes soil ionisation under lightning surge condition
2008
The non linear effects of soil ionisation on the behaviour of earth electrodes are investigated by a finite difference time domain numerical scheme. A time variable soil resistivity is used in order to simulate the soil breakdown; step by step the resistivity value is controlled by the local instantaneous value of the electric field compared with the electrical strength, fixed for the soil. No a priori hypothesis about the geometrical shape of the ionised zone around the electrodes has to be enforced. Simulation results related to complex earth electrodes of limited extension are reported. The model has been validated by comparing the computed results with data available in technical litera…
Finite difference time domain simulation of soil ionization in grounding systems under lightning surge conditions
2004
This paper proposes a Maxwell’s equations finite difference time domain (FDTD) approach for electromagnetic transients in ground electrodes in order to take into account the non linear effects due to soil ionization. A time variable soil resistivity method is used in order to simulate the soil breakdown, without the formulation of an initial hypothesis about the geometrical shape of the ionized zone around the electrodes. The model has been validated by comparing the computed results with available data found in technical literature referred to concentrated earths. Some application examples referred to complex grounding systems are reported to show the computational capability of the propos…
Soil ionization of earth electrodes under high pulse transient currents
2007
This paper proposes a numerical model of soil ionization phenomena that can occur when earth electrodes are injected by high pulse transient currents. The model is solved by a finite difference time domain numerical scheme. It has been developed from a thorough analysis of the available studies in technical literature about the peculiar physical dynamics of soil ionization phenomena. As already underlined, soil ionization can occur, for example, when the earth electrode has to drain a lightning current into the soil. In this case, the electric field can overcome the electrical strength and conductive plasma paths can locally grow. The dimension of these ionized air channels are strictly dep…