Fundamental Research for Practical Application of Cryogenic Gas Insulated Transmission and Substation Apparatus with Environmentally Friendly Nature

近年来，随着对环境友好性质的日益关注，对自然环境几乎没有影响的绝缘气体现在被高度期望。对低温氮气和低温空气在气体绝缘电器中的应用进行了研究和探讨。在一个容积为1.1 m^3的大型低温恒温器中，测量了气体绝缘间隙的击穿电压和电晕放电特性，并改变了气体的混合比和温度。此外，为了弄清放电过程，利用气体克尔效应研制了一种新的电场测量系统。实验结果总结如下：1.测量了直径为150 mm、间隙长度为10 ~ 100 mm的球形电极间准均匀电场间隙的击穿电压。在差距上施加50 Hz的交流和直流电压时，即使在低温（93 K）下，在氮气和空气中的击穿电压也服从帕邢定律.观察到的放电特性与一个不均匀的场间隙的棒到平面电极的几何形状高达330毫米的直流电压应用在氮气和合成空气在室温和低温。在室温下的合成空气中，刚好低于击穿电压的电晕放电具有覆盖棒电极的薄膜形状，并且击穿电压极高。击穿电压随差距长度在0- 200 mm范围内过度增大，在200 mm以上达到饱和.利用气体自身的克尔效应，研制了一种不产生任何场干扰的气体电场光学测量系统。成功地测量了SF_6、CO_2和氮气中的直流电场，测量范围达50 kV/cm。

In recent years, insulation gases which have little effect on the natural environment are now highly expected with increasing interest of environmentally friendly nature. The application of nitrogen or air at cryogenic temperature to gas insulated electrical apparatus is examined and discussed.The breakdown voltage of gas insulated gap and its corona discharges characteristics in a large cryostat whose inner volume is 1.1 m^3 are measured changing the mixture ratio and the temperature of the specimen gases.In addition, to clarify the process of the electrical discharge, a new electric field measurement system is developed by using gaseous Kerr effect. The experimental results are summarized as follows :1. The breakdown voltages of a quasi-uniform electric field gap between sphere electrodes with a diameter of 150mm and a gap length of 10 to 100mm are measured. When 50 Hz ac and dc voltages are applied to the gap, the breakdown voltages in nitrogen and air obey Paschen's law even at cryogenic temperatures (93 K).2. The discharge characteristics are observed with a non-uniform field gap of a rod-to-plane electrode geometry up to 330mm for dc voltage applications in nitrogen and synthetic air at room and cryogenic temperatures. In synthetic air at room temperature, the corona discharge just below the breakdown voltage has a shape of a thin film covering the rod electrode, and the breakdown voltage is extremely high. The breakdown voltage increases excessively with the gap length in the range of 0-200mm and is saturated in the range over 200mm.3. A new optical measurement system is developed for measuring electric field in gas without causing any field disturbance by using Kerr effect in gas itself. dc electric field in SF6, CO2 and nitrogen is successfully measured up to 50kV/cm.