Measurement of Soil Resistivity for an HVDC Electrode Station Using High Current DC Source

This paper describes the investigation of soil resistivity carried out at proposed HVDC electrode site in India. Soil resistivity does not have a constant value throughout the zone of investigation, it varies widely in the lateral direction as well as, has large and abrupt changes in vertically distinct strata. Therefore, accurate soil resistivity data is an essential part of proper investigation of sites for grounding system design and installation. Measurement of soil resistivity corresponding to various depths are required for adequate evaluation of proposed installation sites. The traditional method of measurement of soil resistivity is by using earth testers. Alternate source, like high current DC can be used for measurement of soil resistivity during the design of grounding systems for applications like HVDC electrode stations. Usage of high current DC source for soil resistivity measurement application is not that popular. In this paper, the measurement of soil resistivity performed using high current DC source is explained and the results obtained are analyzed. This will provide an insight to personnel involved in design of earthing system for special application.