Fundamental research for applying post SF_6 gas insulation concept to electric power apparatus with low environmental load

我们新引进了一个陡前沿方波电压发生器，它实现了16 ns的上升时间和200 kV的峰值，并研究了纳秒范围内的气体放电特性，重点是击穿和火花放电电压的概率分布和时间滞后特性，包括VFTO问题。SF6气体是大多数电力设备中的主要绝缘介质，具有较高的温室效应，有望成为环境效应较低的替代品。研究了SF_6-N_2混合气体、CF_3I、空气和氮气等环境友好气体的放电特性，发现SF_6-N_2混合气体的击穿电压与混合气体的配比存在协同效应。我们已经澄清，即使在很短的时间范围内建立的效果约10 ns，通过使用陡峭的前端方波电压发生器。在相同条件下，CF 3 I气体的介电强度是SF6气体的1.2倍。虽然CF 3 I气体的缺点是烧结温度较高，但可以通过与其他气体混合降低分压来克服。空气和氮气对环境完全没有影响，与SF6气体相比，其介电强度约为三分之一。然而，通过冷却可以在保持相同压力的情况下增加介电强度。在液氮温度下，如果保持相同的压力，介电强度变为室温的3.8倍。这相当于在室温和相同压力下的SF6气体。

We have newly introduced a steep-front square voltage generator, which realizes a rise time of 16 ns and a peak value of 200 kV, and investigate gaseous discharge characteristics in nanosecond range focusing the probability distributions of breakdown and sparkover voltage and time lag characteristics including VFTO problems.SF6 gas, which is the main insulating medium in most electrical power apparatuses, has high greenhouse effect and the substitute with lower environmental effect are expected. We have investigated the discharge characteristics of environmentally friendly gases such as SF6-N2 gas mixture, CF3I, Air and nitrogen gas.It is already known that the breakdown voltages in SF6-N2 gas mixtures have synergistic effect against the mixture ratio. We have clarified that the effect is established even in very short time range around 10 ns by using the steep-front square voltage generator. CF3I gas has 1.2 times as high dielectric strength as SF6 gas under the same condition. Although CF3I gas has a weak point that the liquefying temperature is rather high, it can be overcome by mixing with other gases to lower the partial pressure.Air and nitrogen gas, which has completely no influence on the environment, has about a third dielectric strength as compared to SF6 gas. It is, however, possible to increase the dielectric strength keeping the same pressure by cooling. At the liquid nitrogen temperature, the dielectric strength becomes 3.8 times higher than that of room temperature if keeping the same pressure. This is equivalent to SF6 gas at room temperature and the same pressure.