Majlesi Journal of Electrical Engineering Breakdown Characteristics of Oxygen, Nitrogen, O2+N2 and SF6+N2 Gas Mixture as Substitute Gases of SF6 In Press 2024 06 02 Breakdown Characteristics of Oxygen, Nitrogen, O2+N2 and SF6+N2 Gas Mixture as Substitute Gases of SF6 EN Norsuhada Zainal Abidin Department of Electrical Engineering, Faculty of Electric and Electronic, Universiti Tun Hussien Onn Malaysia, Parit Raja, Malaysia 0009-0004-3806-527X Muhammad Saufi Kamarudin Department of Electrical Engineering, Faculty of Electric and Electronic, Universiti Tun Hussien Onn Malaysia, Parit Raja, Malaysia 0000-0002-6112-6171 Erwan Sulaiman Department of Electrical Engineering, Faculty of Electric and Electronic, Universiti Tun Hussien Onn Malaysia, Parit Raja, Malaysia 0000-0003-0303-6191 Journal Article 2024 06 02 Sulfur hexafluoride (SF6) is extensively utilised as an essential insulating material in high-voltage industries owing to its outstanding electrical characteristics. However, the use of SF6 gas faces two significant challenges: its substantial impact on global warming and the high toxicity of its breakdown byproducts. This study aims to analyse the breakdown properties of various gas and gas mixtures, including, pure Nitrogen (N2), pure Oxygen(O2), O2+N2 gas mixture, and SF6+N2 gas mixture as alternative insulation media under positive standard lightning impulses. The experiments involve sphere and plate electrodes with varying gap distances. Following the BS EN 60060-1 standard, the breakdown voltage is measured using the Up and Down method, with a voltage interval between levels set between 1.5% and 3%. Based on the findings, N2 gas has been determined to be a highly efficient insulator, outperforming other options. The reason for this is its superior breakdown voltage, which reaches 37.415 kV, surpassing the values of other gas and gas mixtures.