Impulse Polarity Effect on Soil-Enhancement Material Mixtures

This paper aims to study the breakdown characteristics of enhancement materials mixtures under both positive and negative impulse polarities. Sand is considered where it is mixed with 5% and 10% of water content, and mixed with several percentage of enhancement material (EM), filled in a parallel plate test cell and subjected under both impulse polarities. Results are analysed at both pre-breakdown and breakdown levels, where impulse impedance, Zimp, breakdown electric field, E<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50</inf> and v-t breakdown curves were compared for both impulse polarities. From the obtained results, it is found that the Zimp, E<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50</inf> and time to breakdown are improved with the presence of EM. Higher Zimp was seen in positive impulse than those obtained for negative impulse polarity. The established data obtained from this work will not only be helpful in understanding the breakdown mechanism of soil-EM mixtures under both impulse polarities, but also it can be considered in representing the equivalent circuit of grounding systems correctly in the simulation work.