Indonesian Journal of Electrical Engineering and Computer Science Vol. 20, No. 2, November 2020, pp. 569~574 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v20.i2.pp569-574  569 Journal homepage: http://ijeecs.iaescore.com Effects of lightning impulse front time on substation grounding system performance Muhammad Adnan 1 , Zulkurnain Abdul-Malek 2 , Nur Syazwani Mohd Din 3 Muhammad Irfan Jambak 4 , Zainuddin Nawawi 5 , Muhammad Abu Bakar Sidik 6 1,2,3 Institute of High Voltage and High Current, School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Malaysia 4,5,6 Department of Electrical Engineering, Faculty of Engineering, Universitas Sriwijaya, Indonesia Article Info ABSTRACT Article history: Received May 7, 2020 Revised Jun 20, 2020 Accepted Jul 8, 2020 The role of the grounding system in the safety of the power system and protection of personnel is obvious during an unexpected short circuit or lightning discharge at the substation. The aim of this work is to analyze the effects of several parameters: lightning impulse front time, soil resistivity and types of grid materials on the grounding system of the Substation. The ground potential rise (GPR), touch voltage and step voltage of a 50 m x 60 m grounding grid buried at a depth of 0.5 m were computed using CDEGS when injected by impulse with different front times. Results show that the shorter the front time of lightning impulse waveform, the higher the value of GPR, touch voltage and step voltage. Meanwhile, when the value of soil resistivity is increased, the value of GPR, touch voltage and step voltage is also increased. Lastly, different types of grid conductor materials give different values of GPR, touch voltage and step voltage. However, it can be said that the differences are too small to be of any significance. Keywords: Grounding grid Ground potential rise Touch voltage Step voltage Front time Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Zulkurnain Abdul-Malek, Institute of High Voltage and High Current, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia. Email: zulkurnain@utm.my 1. INTRODUCTION The role of a proper grounding system of the substation is very vital. The role of the grounding system comes into play for the protection of power grid equipment’s and personnel safety, During normal and in an unexpected lightning interruption on substation. Lightning impulse on the substation can be classified into lightning impulse current waveform and lightning impulse voltage waveform. Two types of lightning impulse current waveforms which are direct lightning current and indirect lightning current waveform. the level of voltages should be made minimum as possible to ensure the reliability and safety of the substation. When designing the grounding system of a substation, Ground potential rise (GPR), touch voltage, and step voltage are considered as an important parameter to be observed and analyzed. A good design should maintain the value of touch voltage and step voltage under the safety limits. In addition, the grounding system design should have a very low ground resistance with a tolerance of touch voltage and step voltage limits [1]. A higher than expected potential rise can cause harm to the safety of a person nearby and also to the equipment of the substation.