Six, sulfur fluoride is a colorless, odorless, non-toxic and nonflammable inert gas. Its molecular weight is 146.07. When it is 20 and 0.1 MPa, its density is 6.1kg/m3, which is about 5 times the air density. Six sulfur fluoride is gaseous at normal temperature and atmospheric pressure. The critical temperature is 45.6 C, the three phase point temperature is -50.8 C, and the sublimation temperature is -63.8 C under normal pressure. Six, the structure of sulfur hexafluoride is arranged in eight sides. The bonding distance is small and the bonding energy is high. Therefore, its stability is very high. When the temperature is no more than 180 degrees, its compatibility with electrical structure materials is similar to that of nitrogen.

简介

brief introduction

SF6气体已有百年历史，它是法国两位化学家Moissan和Lebeau于1900年合成的人造惰性气体，1940年前后，美国军方将其用于曼哈顿计划（核军事）。

SF6 gas has been in the history of 100 years. It is an artificial inert gas synthesized by two chemists in France, Moissan and Lebeau in 1900. Before and after 1940, the US Army used it in the Manhattan plan.

SF6是强电负性气体，它的分子极易吸附自由电子而形成质量大的负离子，削弱气体中碰撞电离过程，因此其电气绝缘强度很高，在均匀电场中约为空气绝缘强度的2.5倍。SF6气体在t≈2000K时出现热分解高峰，因此在交流电弧电流过零时，SF6对弧道的冷却作用比空气强得多，其灭弧能力约为空气的100倍。由于SF6气体具有优良的灭弧性能和绝缘性能以及良好的化学稳定性，它从20世纪50年代末开始被用作高压断路器的灭弧介质。在超高压和特高压断路器中，SF6作为灭弧介质，已取代油，并已大量取代了压缩空气。

SF6 is a strong electronegative gas. Its molecules are easy to adsorb free electrons and form large negative ions and weaken the impact ionization process. Therefore, its electrical insulation intensity is very high, and it is about 2.5 times of the air insulation strength in the uniform electric field. SF6 t is 2000K when the gas in thermal decomposition peak, so zero in AC arc current, the cooling effect of SF6 arc is much stronger than the air, the arc capacity is about 100 times the air. Because SF6 gas has excellent arc extinguishing and insulation performance and good chemical stability, it has been used as an arc extinguishing medium for high voltage circuit breaker since the end of 1950s. In UHV and UHV Circuit breakers, SF6, as an arc extinguishing medium, has replaced oil and has replaced a large number of compressed air.

从60年代中期起，SF6被广泛用作高压电气设备的绝缘介质。SF6气体绝缘的全封闭开关设备比常规的敞开式高压配电装置占地面积小得多，且其运行不受外界气象和环境条件的影响，因此不仅广泛用于超高压和特高压电力系统，而且已开始用于配电网络(SF6气体绝缘的开关柜和环网供电单元)。SF6气体绝缘的管道输电线的优点是介质损耗小、传输容量大，且可用于高落差场合，因此常用于水电站出线，取代常规的充油电缆。SF6气体绝缘的变压器具有防火防爆的优点，这种配电变压器特别适用于人口稠密的地区和高层建筑的供电。SF6气体绝缘的超高压变压器已研制成功，全气体绝缘变电所将是变电技术发展的一个方向。[1]

Since the mid 60s, SF6 has been widely used as an insulating medium for high voltage electrical equipment. Full closed switch equipment of SF6 gas insulated than conventional open type high-voltage distribution device covers an area much smaller, and the operation is not affected by external environment and weather conditions, so it is not only widely used in EHV and UHV power system, and has been used in the distribution network of SF6 (gas insulated switchgear and ring network power supply unit). The advantages of SF6 gas insulated pipeline transmission line are small dielectric loss, large transmission capacity and high drop application. Therefore, it is commonly used for hydropower stations to replace conventional oil filled cables. SF6 gas insulated transformers have the advantages of fireproof and explosion protection. This distribution transformer is especially suitable for the power supply of densely populated areas and high-rise buildings. The ultra high voltage transformer of SF6 gas insulation has been developed successfully. All gas insulated substation will be a direction of the development of the transformer