| Title |
Breakdown Characteristics of Soils Caused by Impulse Currents |
| Authors |
Bok-Hee Lee ; Kang-Soo Lee ; Hoe-Gu Kim |
| DOI |
http://dx.doi.org/10.5207/JIEIE.2010.24.4.103 |
| Keywords |
Soil Ionization ; V-I Curve ; Breakdown Voltage ; Lightning Current ; Transient Grounding Impedance ; Time-Lag To Breakdown |
| Abstract |
In this paper, breakdown characteristics of soil in a coaxial cylindrical electrode system stressed by impulse currents were experimentally investigated. The breakdown voltage and current waveforms for 4 types of soils were measured, and the threshold electric field intensity, the time-lag to breakdown and the voltage-current (V-I) curves were analyzed and discussed. As a result, the breakdown voltage and current waveforms are strongly dependent on the grain size of soil, and the voltage and current waveforms for gravel and sand differ from those for silt and loess. The threshold electric field intensity Ec is increased in the order of gravel, sand, loess and silt. The V-I curves for all test samples show a ‘cross-closed loop’ of ∞-shape. Also, the time-lag to breakdown for gravel and sand are longer than those for silt and loess. It is expected that the results presented in this paper will provide useful information on the design of improving transient performance of a grounding electrode system subjected to lightning current considering the soil ionization. |