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Analysis on the Voltage Drop of Off-Grid Single Wire Earth Return (SWER) Distribution Line and its Potential Applications in a Micro-hydro System

Roderick L. Catriz1, Rossana Marie C. Amongo2, Arthur L. Fajardo 2, and  Chiliast B. Juan3



Single Wire Earth Return (SWER) is a power distribution using only one wire and having the ground as the return path.  This can be used as electrical distribution system for a micro-hydro power source which is location-specific and may not be readily accessible and connected to the grid. The need for an effective electrical distribution system is necessary to maximize its power utilization. A 500-meter SWER distribution system was installed in a Lipa soil series to determine the effects of different factors (i.e. amount of voltage source, load resistance, distance from the source and depth of the grounding rod) affecting voltage drop of the ground. The ratio of voltage drop over voltage source was taken to determine the effectiveness of SWER as distribution system. Results showed that SWER is influenced by the following factors in descending order of importance: load resistance, depth of copper rod, distance, and finally the voltage source.  Moreover, voltage drop is correlated to all the independent factors (Distance=0.175, Depth=-0.542, Vsource=0.470 and Load=-0.408).  Regression analysis was undertaken to determine the best model describing voltage drop. The best model with the highest value of the adjusted R2 of 86.6% was chosen to describe the behavior of voltage drop. 

Keywords: Single-Wire Earth Return (SWER), single conductor, voltage drop, distribution line, Lipa soil series

 1 Assistant Professor, Electrical Engineering Department (EED), College of Engineering Agro-Industrial Technology, (CEAT); 2Assistant Professor, Agricultural Machinery Division (IAE), Institute of Agricultural Engineering (IAE), CEAT; and 3BSEE Graduate, EED, CEAT, University of the Philippines Los Baños, 4031 College, Laguna, Philippines.