Analysis of the Insulation Characteristics of Hexafluorobutene (C\({}_{4}\)H\({}_{2}\)F\({}_{6}\)) Gas and Mixture with CO\({}_{2}\)/N\({}_{2}\) as an Alternative to SF\({}_{6}\) for Medium-Voltage Applications  
[PERSON]  
1 Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia,  
Batu Pahat 86400, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
1 Faculty of Electrical and Electronic Engineering, University Tun Hussein Onn Malaysia,  
Batu Pahat 86400, Malaysia; [EMAIL_ADDRESS]  
[PERSON]  
2 Architecture and City Design Department, King Fahd University of Petroleum & Minerals, Box #684,  
Dhahran 31261, KFUPM, Saudi Arabia  
[PERSON]  
2 Architecture and City Design Department, King Fahd University of Petroleum & Minerals, Box #684,  
Dhahran 31261, KFUPM, Saudi Arabia  
[PERSON]  
3 Advanced High Voltage Engineering Research Center, School of Engineering Cardiff University,  
Cardiff CF10 3 AT, UK  
below 2 \({}^{\circ}\)C [4]. SF\({}_{6}\) was one of the six primary greenhouse gases included in the Kyoto Protocol in 1997 [5,6]. This makes it imperative to work on decreasing or capping SF\({}_{6}\) use. The pursuit of a gas insulation medium that may substitute SF\({}_{6}\) as safely as possible has gained significant attention in recent years. Therefore, the realization of SF\({}_{6}\)-free practices has now become a crucial task for the green development of power grids. Many studies have been carried out throughout the years on the insulating capacities of several gases as SF\({}_{6}\) substitutes [7, 8, 9]. No gas or gas mixture has been found to this day which can completely replace SF\({}_{6}\). Hence, gases that can replace SF\({}_{6}\) must have (1) outstanding physicochemical properties, such as a low liquefaction temperature, low toxicity, good thermal and chemical stability, and non-flammability; (2) exceptional insulation and arc quenching abilities; and (3) excellent environmental characteristics, specifically low GWP and Ozone Depletion Potential (ODP) values [10]. ODP is defined as \"Relative amount of degradation caused to the ozone layer compared with trichlorofluoromethane (R-11 or CFC-11) being fixed at an ODP of 1\({}^{\prime\prime}\). Two types of alternatives to SF\({}_{6}\) were investigated: naturally occurring buffers and synthetic gases. Buffer gases include natural gases (CO\({}_{2}\), N\({}_{2}\), and dry air) [11, 12, 13], and synthetic gases include gases such as PFCs, CF\({}_{3}\)I, and c-C\({}_{4}\)Fs [1417]. The use of buffer gases such as carbon dioxide as a dielectric medium requires large equipment due to momentous expansion in pressure. Moreover, 100% CO\({}_{2}\) insulation characteristics are only around 40% of SF\({}_{6}\). Although carbon dioxide's safety and low cost are advantageous factors, implementing it in practical medium-voltage applications would require replacing the existing equipment with bulky construction to sustain high pressure to provide sufficient dielectric strength. Synergistic effects allow for a decrease in GWP proportional to the admixture ratio in SF\({}_{6}\)-based gas mixtures like SF\({}_{6}\)/N\({}_{2}\) and SF\({}_{6}\)/CF\({}_{4}\) while maintaining usable electric characteristics [12]. Tetrafluoropropene, a novel chemical with four interesting properties, was only discovered recently [13]. It was determined that fluoroketones (C\({}_{5}\)-FK) [14], fluoronitriles (C\({}_{4}\)F\({}_{7}\)N) [15], and trifluoroiodomethane [16] have sufficient electric strength to be employed in electrical equipment under realistic working circumstances. They are usually mixed with low-boiling-point gases, such as carbon dioxide (CO\({}_{2}\)) or nitrogen (N\({}_{2}\)), when utilized in HV applications because of their high boiling points. The new alternatives have an electric strength comparable to SF\({}_{6}\) and a reduced GWP. Despite the fact that the aforementioned new ecologically friendly insulation gases have been researched and suggested, none of them are a satisfactory substitute because they all have drawbacks.