SF6 gas, sulfur hexafluoride, is a colorless, odorless, non-toxic gas. It has special chemical properties that make it an ideal insulator and arc extinguishing medium. The following will explain why SF6 gas has good insulation and arc extinguishing properties from the aspects of molecular structure, chemical properties, and physical properties.
First, the molecular structure of the SF6 molecule determines its good insulation performance. The SF6 molecule consists of one sulfur atom and six fluorine atoms and has an octahedral structure. The sulfur atom is at the center of the octahedron, and the fluorine atoms are evenly distributed on the eight vertices. This structure makes the polarity of SF6 gas very high and has a strong polarization ability in the electric field. The polarization effect enables SF6 gas to effectively prevent the flow of current, thus having excellent insulation properties.
Secondly, SF6 gas has a high breakdown voltage and arc extinguishing performance. The breakdown voltage refers to the lowest voltage value at which the insulating medium breaks down under the action of the electric field. Experiments show that the breakdown voltage of SF6 gas is much higher than that of other common gases, such as air and nitrogen. This is because the positive and negative charges formed after the polarization of SF6 molecules make the internal electric field of the gas evenly distributed, and the free path of electrons in the gas is short, so it is not easy to ionize and cause breakdown.
In addition, SF6 gas also has good arc extinguishing performance. Arc extinguishing refers to the process of quickly extinguishing the arc when the current transmission ends in high-voltage equipment. SF6 gas has a high ion density and chemical stability. When the current passes through zero, it can quickly absorb and eliminate free electrons and ions in the arc, thereby achieving reliable arc extinguishing. Moreover, SF6 gas has high thermal stability, is not prone to thermal decomposition, can withstand high arc temperatures, and effectively prevents the arc from igniting again.
In summary, SF6 gas has become an ideal insulator and arc extinguishing medium due to its special molecular structure, high breakdown voltage and arc extinguishing performance. In high-voltage power transmission and distribution systems, SF6 gas is widely used in equipment such as circuit breakers, cable terminals and substations. Its good insulation and arc extinguishing performance ensure the safe and stable operation of equipment and improve the reliability of the power system.
