Impulse Characteristics of Highly Wetted Soils

Abstract

It has been well accepted that under high impulse conditions, ionisation process in soil would occur, causing the ground resistance value to fall to a lower value than that obtained at low voltage low current, RDC. Factors affecting the percentage of reduction of impulse impedance from its RDC values have been known to be caused by soil resistivity, ground electrode’s configuration/sizes, RDC values, magnitudes and response time of impulse current. In this paper, experimental results of sand mixed with various soils and water content filled in a cylindrical container, subjected to high impulse currents are presented. The results are discussed according to the current impulse shape, impulse impedance and the breakdown voltage of the test cell.

Keywords

• high impulse conditions
• ionisation process
• ground resistance value
• impulse impedance
• impulse breakdown