Estimation of critical electric field of soil ionisation based on tangential electric field method

Abstract

The critical electric field of soil ionisation is very important for the performance of grounding system and spatial distribution of electromagnetic field in the soil when lightning directly strikes the lightning protection system. To estimate the critical electric field in the soil, a tangential electric field method is proposed based on the electromagnetic field analysis presented in this study. With this method, the instant moment when the soil ionisation occurs is obtained by examining the tangential component of horizontal electric field. According to the maximum electric field in soil without soil ionisation for every moment, the soil critical electric field could be estimated. In addition, the critical electric fields for four different types of soil reported in the literature are estimated with the tangential electric field method, yielding satisfactory agreement.

Research on impulse impedance model and protection optimization of transmission tower grounding device in mountainous area

“…The soil resistivity is set to the relation function between the resistivity of red soil and the electric field intensity. In other researches, the permittivity of soil is usually set as 1, 4, 5, 8 and 9 [2, 5, 14, 27]. In the research process of this paper, the permittivity of red soil is set to 8, which is within the experimental measurement range of 7.8–8.3.…”

“…In addition, the model can also be used to analyze the impact of lightning current frequency on the impact characteristics of the grounding body [8]. With the application of the electromagnetic field theory method, the authors in [10][11][12][13][14][15] studied the influence of both soil nonlinear characteristics and grounding grid structure on impact characteristics, and then analyzed the transient characteristics of grounding devices. The calculation model based on the circuit-finite element method proposed in this paper can comprehensively consider the nonlinear effect of the soil and the high-frequency inductance effect of the grounding device.…”

Soil impulse ionisation model based on dynamic changes of electric field

“…Electric breakdown theory holds that soil ionisation is caused by breakdown of the gas between soil particles [2,3], while thermal breakdown theory holds that soil ionisation is caused by evaporation of water in soil [4]. In order to consider the effect of soil ionisation in calculation, the critical electric field value E c which determines the initiation of soil ionisation process needs to be defined first [5,6]. Lots of impulse experiments on grounding electrodes have been carried out, the E c was chosen with the principal of better match of theoretically predicted results and experiment results.…”

Hybrid continuous circuit‐trapezoidal integration method analysis of multi‐cross structure of grounding system

“…The results of this paper are compared with both theoretical approaches and experimental measurements and show acceptable agreement. In these investigations, the soil ionisation phenomena could be simulated more accurately considering experimental results in [34]. A model based on the transmission line approach that incorporates both mutual coupling and air-soil interface effects, giving a more realistic representation of the grounding systems behaviour, is proposed in [16].…”