A study on electrical resistivity characteristics of Pakistani coal char for earth grounding system

Abstract

In this study we aim to investigate the electrical conductivity and physiochemical properties of the selected coal samples for their application in earth grounding systems. Three different ranked coals namely Thar brown lignite (BL), Chamalang bituminous coal (BC) and semi-anthracite Dera Adam Khail (SC) coals were selected and their respective chars were prepared at 4500 C and subjected to the ground resistivity potential test using the universal earth grounding tester.  Through experiments, it was found that BL coal has the least reactivity value and best conducting properties for electric current, followed by the SC and BC in descending order. It has been suggested that high moisture content and dissolved salts may act like an electrolytic medium for current passage in BL that is the reason for low resistivity value. The presence of low conductivity minerals in small percentage having relatively higher mass could be the reason for higher resistivity value in coal samples. Moreover, compared to raw coals, prepared char samples showed an improvement in electric current conductivity and lowered the resistivity values for all the ranks of selected samples.