Theoretical Characterizations on the Eco-Friendly Gas Tetrafluoropropyne for Electrical Insulation to Replace Sulfur...

Gases for electric insulation are essential for various types of high-voltage power equipment. Sulfur hexafluoride (SF₆) has been a dielectric medium commonly used in electrical grids for decades but it is the most potent industrial greenhouse gas. The continuous increase of SF₆ emissions in the atmosphere exerts a significant impact on global warming. The identification of suitable drop-in replacements for all SF₆-filled apparatuses has been elusive experimentally and theoretically. We claim that tetrafluoropropyne, C₃F₄, is a breakthrough in chemical alternatives to SF₆. The performance of C₃F₄ was assessed systematically in a 6-dimensional manner, including dielectric strength, liquefaction temperature, global warming potential, thermal stability, toxicity, and arc interruption. On the basis of the extensive ab initio calculations, it has been demonstrated rigorously that C₃F₄ is an environmentally sustainable solution that may fulfill the complex combination of performance, stability, safety, and environmental properties, namely, the dielectric strength is about 50% higher than that of SF₆, the boiling point is -50 °C, the GWP for 100 year time horizons is only 3, the decomposition temperature is above 600 °C, the toxicity is as low as HFOs, and the interruption capability is two-thirds of SF₆. Two protocols are suggested for the practical use of C₃F₄. First, equivalence to 0.5 MPa SF₆ could be obtained by filling 0.33 MPa C₃F₄ pure gas and lead minimum operating temperature down to -21 °C. Second, by taking advantage of synergism effect, the 40% C₃F₄/60% CO₂ mixture is a viable alternative to SF₆ with the operating temperature -30 °C without causing any environmental and safety concerns. The present theoretical work sheds new light on the challenging topic of the development of alternative dielectric gases and may stimulate experimental tests on the electrical applications of C₃F₄ in the future.