Proposed Approach to Investigate the Current and Voltage Distributions of Isolated and Grounded Systems During Earth Fault Conditions

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Abstract
One important objective of this article is to present a novel approach to study the current density and ground surface potential around the area surrounding earthed and isolated systems in the event of a line-to-earth fault. The present study is done in the case of uniform and two layers of soil. The contact and arc resistances of the line-to-ground faulty conductors are considered. A grounded system is usually implemented with rods and/or grounding grids, the impact of both on step and touch potentials and current density are investigated, discussed, and adapted. The methods of the calculations are based on the electrical concepts, the charge simulation method, and the image method for the grounding system. The results obtained are in agreement with that reported by others, with the benefits of the proposed algorithm for its ease of application, simplicity, and it does not need complex computer programs or a long time in calculations. 3-D dimensions contours of the current density and the electric potential on the earth’s surface around the faulty point in case of homogeneous and two layers of soil are presented, whether the network is grounded or isolated. Comparing the results obtained with those reported by the others, differences of 2.2% in the Ground Potential Rise, 2.46% in the current density, and 0.5% in the fault current passes into the isolated system are recorded. These values in the differences are within the acceptable limits.
Funding Information
  • Department of Electrical Engineering and Automation, School of Electrical Engineering, Aalto University, Espoo, Finland

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