| Title |
A Basic Study on the Attachment Process of Lightning Leader to Ground |
| Authors |
Yang-Woo Yoo ; Seung-Min Kim ; You-Ha Kim ; Bok-Hee Lee |
| DOI |
http://dx.doi.org/10.5207/JIEIE.2014.28.10.082 |
| Keywords |
Lightning ; Lightning Leader ; Attachment Process ; Lightning Impulse Voltage ; Discharge Voltage ? Time-lag Curve ; Soil Surface Discharge |
| Abstract |
This paper presents the results of model tests for the attachment process of lightning leader to ground which is one of poorly understood processes of cloud-to-ground lightning discharges. In order to simulate the attachment process of lightning leader to ground, we investigated the discharge characteristics of air gap between the tip of needle-shaped electrode and the soil surface as a parameter of moisture content in soils when the positive and negative 1.2/50㎲ lightning impulse voltages are applied. The breakdown voltage and the discharge light were observed. As a result, the attachment processes of lightning leader to ground are strongly dependent on the grain size and the moisture content of soils. The time to breakdown was shortened with increasing the magnitude of incident impulse voltages. The delay time from application of the highest voltage to breakdown in sand is shortened with increasing the moisture content. The delay time from application of the voltage to breakdown in gravel varied from about 0.5㎲ to several ㎲. As the moisture content in soil increases, the breakdown voltages are decreased and the breakdown voltage versus time to breakdown curves are shifted toward the lower side. The results obtained in this work are similar to those for non-uniform air gap stressed by lightning impulse voltages. |