Effective earthing system of electrical power engineering department using optimal electrodes

Abstract

Some of the buildings in Myanmar are not provided with a reliable earthing system for protection against electric shock. Thus, residents, equipment around this environment may experience the electrocution under fault conditions that often occur in the rainy season among three seasons. Soil resistivity completely influences on the making of the earthing system. When the economical and effective earthing system creates, location of the area must be the lowest soil resistivity. In this research, electrical power engineering department in Pyay city, one storey reinforced cement concrete building, is chosen for the earthing system. Neutral earthing system of the power supply source and building’s installation earthing system is considered. Three conditions for the reduction of earthing resistance value by changing the three variables of earth electrode. A mixture of clay and sand soil is selected as a uniform soil resistivity for both earthing systems. The vertical earth rod is exploited as an electrode to carry and drive the fault current to the earth. Copper rod is elected because of less corrosion and more conductivity than any other materials. The terre-terre (TT) earthing system is applied as an earthing method and parallel configuration is used for multiple electrodes in rectangular shape for six rods and equilateral triangle shape for three rods to achieve the acceptable earth resistance according to IEEE 142 and BS 7430. Results of earth resistance on the variant forms of diameter, length and numbers of earth rods and minimum earth conductor size are revealed for supply transformer and building earthing system.