A Systematic Approach to Safe and Effective Earthing System Design for High Voltage Substation

Abstract

In high voltage substation, earthing system is an essential part not only for providing the protection to people who are working or walking in the vicinity of earthed facilities and equipment against the danger of electric shock, but also for maintaining the proper function of the entire electrical system. By selecting a proper conductor and electrode size based on standard criteria, the existence of large potential differences during fault or lightning conditions will able to be avoided. Standard equations for earthing are used in the design to obtain the desired parameters such as tolerable touch and step voltage, earth resistance, grid resistance, minimum size of earthing conductor and electrode, as well as resistivity of soil. Therefore, it would enable the establishment of the safe limits of potential differences under both normal and fault conditions. The main objective of this research work is to perform a necessary background information pertinent step by step approach for safe and reliable earthing system design for high voltage distribution substation in Malaysia. It including a set of applicable standard to be used as well as demonstrate an earthing design simulation developed using Microsoft Excel auto mathematical functions. The case study for high voltage substation design and simulation at two locations with different soil resistivity and properties is also performed in this research work. The results revealed that the design of high voltage substation earting system is much dependent on the property and resistivity of soil where the substation will be constructed.