SF6 insulation and arc extinguishing performance are very strong. The molecular weight of sulfur hexafluoride is 5 times that of air, so the operation speed of sulfur hexafluoride ion in the electric field is much smaller than that of nitrogen and oxygen plasma in the air, and it is more prone to compound. Fluorine ion reduces the charged particles of the gas, and the insulation level of sulfur hexafluoride is about 3 times that of air. Fluorine element has the strongest affinity to electron among all elements, so sulfur hexafluoride has strong electronegativity, great attraction to electron, and is easy to form negative ions, so the arc extinguishing performance of sulfur hexafluoride gas is 100 times that of air. Therefore, SF6 insulation is widely used in electrical equipment, and it is the best material for arc extinguishing.

There are two factors that affect the insulation performance of SF6:

One is the content of water vapor in the gas, which is generally called humidity or micro moisture. When the micro water content increases or exceeds the standard seriously, it may cause flashover along the internal surface of the insulation and cause accidents. It may also make the switch insulation parts damp or produce condensation, thus greatly reducing its insulation performance. At the same time, water will react with sulfur hexafluoride decomposition products decomposed by the arc to generate highly corrosive HF (hydrofluoric acid), sulfurous fluoride (SOF2), sulfur difluoride (SO2F2) and other acidic substances, which will corrode the metal components and sealing insulating materials of the equipment in the arc extinguishing chamber, affect the mechanical properties of the equipment, shorten the service life of the equipment, and reduce the insulation capacity of the equipment It is toxic to human body and pollutes the environment. 

The second is the density of SF6 gas. The density of SF6 gas at 101325pa and 20 ℃ is 6.16g/l. Only SF6 gas with excellent insulation and arc extinguishing electrical performance and a certain density can maintain good arc extinguishing and insulation performance. The relationship between density of liufuhua gas and pressure curve is a positive proportion function, that is to say, to ensure a certain pressure can guarantee a certain degree The density value of. These two factors are directly related to the sealing performance of SF6 Electrical equipment. The sealing performance of SF6 Electrical equipment refers to the ability and condition of sealing gas in each sealing link of electrical equipment.