换流变压器是一种储油量多的充油设备，在高电压等级下有一定的火灾风险，由于其在电网运行中的重要性以及其难燃难灭的特点，其火灾发生将造成长时间停电，产生重大财产损失。从已有的换流变火灾事故来看，目前已有的灭火系统存在包括绝缘破坏，对设备的损坏以及环境破坏等系一列技术不足。因此，寻找一个灭火效率高、绝缘性能强并且环境友好的灭火剂成为了解决换流变火灾的一大方向。全氟己酮灭火剂是一种新型气体灭火剂，灭火浓度较低、不会对环境产生显著影响，因此为解决换流变压器火灾提供了一个新思路。本文将从全氟己酮与换流变设备材料的相容性、绝缘特性以及灭火特性三个方面来研究探索全氟己酮应用于换流变压器火灾的可行性。本文首先研究了全氟己酮的材料相容性。全氟己酮与金属材料具有良好的相容性，金属腐蚀速率满足一级可长期使用的金属腐蚀标准，而对电木材料则出现了明显的溶解。全氟己酮会对电力复合脂产生短暂影响，但并未破坏电力复合脂本身的性质，同样具有良好的相容性。本文探究全氟己酮喷洒后形成的混合气体的绝缘特性。灭火前形成的C6F12O-空气混合气体具有良好的绝缘特性，混合比为5%的混合气体击穿电压值近似为空气的1.29~1.8倍，混合气体的击穿电压与混合比呈现正相关关系。灭火后的混合气体产生少量HF、C4F10以及C5F12气体，随着混合比的增大，生成的反应气体进一步减少。反应气体对均匀电场下的击穿强度影响较为明显，当C6F12O占比为7%时，混合气体在均匀电场下的击穿电压下降了5.3%；当C6F12O占比增大，灭火后的C6F12O-空气混合气体击穿电压与灭火前混合气体的击穿电压近似相同。增大火源的功率，此时扑灭火灾后的混合气体击穿电压值的下降呈现了饱和趋势，但仍为空气的1.49倍左右，混合气体的绝缘强度满足要求。最后，通过FDS数值仿真软件研究了全氟己酮在BOX-IN结构换流变中的全淹没灭火性能。结果表明增大流量对全氟己酮扩散的提升效果最为显著；全氟己酮更适用于扑灭前期火灾，对扑灭充分燃烧时的火灾效果不佳，现场试验的结果也对该结论进行了验证。并且，全氟己酮在远距离喷洒时会形成射流、雾化以及气化过程，全氟己酮可以射流距离里灭火效果更好。现有的消防炮并不适用于喷洒全氟己酮灭火剂，可以通过增大流量，减小孔径以及平射等方法来增大全氟己酮射流距离。

The converter transformer is a kind of oil storage capacity of oil-filled equipment. It has a certain fire risk in the high voltage level. The fires of the converter transformer will cause a long time of power outage and result in significant property losses. From the existing converter transformer fire experience, the existing fire extinguishing systems exist a series of technical deficiencies including insulation damage, damage to equipment and environmental damage. Therefore, the search for a fire extinguishing agent with high extinguishing efficiency, strong insulation properties and environmental friendly has become a major direction to solve the converter transformer fires. Perfluoro fire extinguishing agent is a new type of gaseous fire extinguishing agent. Its extinguishing concentration is low, and it does not have a significant impact on the environment. It provides a new way of thinking for solving converter transformer fires. This paper researches and explores the feasibility of applying perfluoro to converter transformer fires from the compatibility of perfluoro and converter equipment materials, insulation characteristics and fire extinguishing characteristics.In this paper, the material compatibility of perfluoro was firstly studied. Perfluoro has good compatibility with metal materials. The metal corrosion rates meet the first level and long-term use of metal corrosion standards, while the phenolformaldehyde plastic appears to be significantly dissolved. Perfluoro has a transient effect on the electrical joint compound, but does not destroy the characteristics of the electrical joint compound. Perfluoro also has good compatibility with and the electrical joint compound. Secondly, this paper also explored the insulation properties of the gas mixture formed after perfluoro spraying. The C6F12O-air gas mixture before fire extinguishing has good insulating properties. The breakdown voltage of the gas mixture with a mixing ratio of 5% is approximately 1.29~1.8 times of that of the air, and the breakdown voltage of the gas mixture increases to more than 2 times of that of the pure air when the mixing ratio is increased to 25%. A small amount of HF, C4F10, and C5F12 gases are generated from the extinguished gas mixture, and the generated reactive gases are further reduced with the increase of the mixing ratio. The effect of the reactive gases on the breakdown strength under a uniform electric field is more obvious. When the electric field is uniform, the breakdown voltage of the gas mixture with a mixing ratio of 7% decreases by 5.3% . When the electric field is extremely non-uniform, the breakdown voltage decreases by about 1% . As the mixing ratio increases, the breakdown voltage of the gas mixture after extinguishing the fire is approximately the same as the breakdown voltage before extinguishing the fire. Increase the power to extinguish the fire source, at this time, the decrease in the value of the breakdown voltage of the gas mixture after extinguishing the fire shows a saturation trend, but it is still about 1.59 times as much as that of air, and the insulating strength of the gas mixture still meets the requirements.Finally, the fully submerged fire extinguishing performance of perfluoro in BOX-IN structural converter transformer was investigated by FDS numerical simulation software. The results show that increasing the flow rate has the most significant effect on the enhancement of perfluoro diffusion. Perfluoro is more suitable for extinguishing the initial stage fire, and is not effective for extinguishing the fire during full combustion. The results of the field test also verify this conclusion. Moreover, perfluoro will form jet, atomization and gasification process when spraying at a long distance. Perfluoro can have better fire extinguishing effect in the jet distance. Existing fire cannons are not suitable for spraying perfluoro fire extinguishing agent, and the distance of perfluoro jet can be increased by increasing the flow rate, decreasing the aperture diameter, and leveling the jet.