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

汽雾介质绝缘的方法是将介质液体的蒸汽和雾气浸入绝缘缓冲气体中，以获得优异的绝缘强度、优良的冷却性能和优异的放电和电晕抑制性能。上一财年的研究结果包括使用C_6F_&lt；14&gt；、(C_4F_9)_3N、FC77、FC40、FC70和FC84作为汽雾介质，证明了大气空气、SF_6和c-C_3F_8缓冲气体的介质强度的改善，证明了汽雾介质的有效性。今年的研究是关于雾化而不是水蒸气改善的机理。由于介电液体的存在使雾气难以分离，故采用介电固体SiO_2微粉作为雾化介质。研究结果如下：1)如果SiO_2微粉架设在电极之间，则在均匀电场下介电强度显著增加。2)如果SiO_2微粉悬浮在电极之间，介电强度增加。3)即使在非均匀电场下，SiO_2微粉悬浮在电极之间也会增加介电强度。4)悬浮细粉提高介电强度可能是由于有助于将细粉悬浮在缓冲气体中的粘性电阻。5)使用SiO_2微粉，可以单独模拟雾的影响。这些结果和前一年的结果一起被描述在本研究工作的报告中，并作为气体介质绝缘的基本数据发表。

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.