Dichlorodifluoromethane-carbon dioxide: A dielectric mixture as a sustainable alternative to SF6 in high voltage applications

Abstract

Sulphur hexafluoride (SF6) gas is the frequently consumed gas in High Voltage (HV) applications due to its high dielectric permittivity and arc-quenching property. However, due to its long Atmospheric Lifetime (AL), high Global Warming Potential (GWP), and other environmental concerns there is a need for a new sustainable gas as an alternative to SF6. Therefore, in this research, we present dichlorodifluoromethane (R-12) in conjunction with carbon dioxide (CO2) as an alternative. Compared to SF6, R-12 has 3,100 years shorter atmospheric lifetime and 15,400 less GWP. Moreover, CO2 is mixed with R-12 as a gas carrier to achieve a low boiling point as that of SF6. High Voltage Direct Current (HVDC), High Voltage Alternating Current (HVAC), and self-recoverability tests were conducted under varying concentrations of gas ratios at different pressures and a standard constant temperature. Comparison analysis showed that R-12 dielectric strength is close to that of SF6, and its mixture with CO2 possessed increased dielectric strength compared to a nitrogen and air mixture beyond 206.84 kPa. For HVAC and HVDC, a mixture of 50% R-12% and 50% CO2 establishes an unimpeachable ratio for HV applications. The mixture has self-recoverability properties and possesses positive synergism, which leads to the conclusion that the mixture of R-12 with CO2 enhances the dielectric strength compared to pure gases, as well as reduces costs.