Mechanism of Increase of Dielectric Strength of Gaseous Dielectics by Vapor Mist

蒸汽雾电介质的绝缘方法是将介电液体的蒸汽和雾浸泡在绝缘缓冲气体中，以获得优异的介电强度、优异的冷却性能和优异的放电和电晕抑制。上一财政年度的研究成果包括使用C_6F_<14>、（C_4F_9）_3N、FC77、FC40、FC70、FC84作为气雾介质，证明了大气缓冲气体SF_6、c-C_3F_8等介质强度的提高，证明了气雾介质的有效性。今年的研究是关于通过雾而不是蒸汽来实现改善的机制。由于介质液体的存在，雾和蒸汽难以分离，因此采用介质固体SiO_2的细粉作为雾剂。研究结果如下：1)在均匀电场作用下，SiO_2细粉桥接电极，可显著提高电极的介电强度。(2)在均匀电场作用下，SiO_2细粉悬浮在电极间可提高介质的介电强度。3)即使在非均匀电场条件下，SiO_2细粉在电极间的悬浮也增加了介电强度。(4)细粉悬浮后介电强度的提高可能是由于缓冲气体中的粘性阻力使细粉悬浮。5)利用SiO_2细粉，可以模拟单独雾化的效果。这些结果与前一年的结果一起在本研究工作报告中进行了描述，并作为气体介电体绝缘的基础数据发表。

Method of insulation by vapor mist dielectrics is to immerse the vapor and mist of a dielectric liquid in an insulating buffer gas to attain excellent dielectric strength, excellent cooling performance and excellent discharge and corona suppression.The results of research in the previous fiscal year include the use of C_6F_<14>, (C_4F_9)_3N, FC77, FC40, FC70 and FC84 as vapor mist dielectrics to prove the improvement of dielectrics strength of the buffer gases of the atmospheric air, SF_6 and c-C_3F_8, demonstrating the effectiveness of vapor mist dielectrics. The research of this year is connected on the mechanism by which the improvement by mist, and not vapor, is attained. Fine powder of dielectric solid SiO_2 is used for mist since of dielectric liquid makes it difficult to separate mist and vapor. The results are as follows ;1) Dielectric strength increases strongly under uniform electric field if SiO_2 fine powder bridges the electrodes.2) Dielectric strength increases unser uniform electric field if SiO_2 fine powder is suspended between the electrodes.3) Even under non-uniform electric field, dielectric strength increases by suspension of SiO_2 fine powder between electrodes.4) The increase in dielectric strength by suspending the fine powder might be explained by the viscous resistance which help suspend the fine powder in the buffer gas.5) By use of SiO_2 fine powder, the effect of mist alone may be simulated.These results together with the the results of the previous year are described in the report of the present research work and published as basic data for gaseous dielectrics insulation.