SHIELDING EFFECT OF SURROUNDED SPACE CHARGE ON THE LIGHTNING STRIKING CHARACTERISTIC TO THE POWER LINE AND THE INVESTIGATION BY ARTIFICIAL TRIGGERED LIGHTNING APPROACH

为了明确围合空间电荷对传输线雷击特性的屏蔽作用，对输电塔电晕放电电流进行了测量，并对传输线进行了并联人工触发雷击试验。从1996年开始的3年间，在日本海附近的奥久井山进行了冬季雷云试验。实验在每年11月进行一个月。结果表明：(1)在60 m高的试验输电塔的8个臂端进行了电晕放电电流测量。最大电流大于500a，在向上电平的一端测得。低层水流相对较小，上层水流较小。(2)雷云照射下，塔身全臂电流的平均电荷量在0.1 C/h左右。(3)利用火箭进行了人工触发闪电实验。首先，火箭携带一个线轴，从线轴上抽出一根尼龙线，然后连接一根电线。尼龙线被用来使电线与地面绝缘。尼龙绳的长度为160米。13次触发的闪电击中了输电线路和输电塔。估计这种空间电荷对输电线路和输电塔的雷击发生在周围空气中。(4)采用另一种触发方式，获得了17次击中地面的触发闪电，并测量了雷电放电通道的电流波形和能量。并成功地进行了另一种观测。(5)这三年共录得30次触发雷击。

In order to make clear the shielding effect of surrounded space charge on the lightning striking characteristic to the transmission line, the measurement of the corona discharge current emitted from a transmission tower was performed, and the artificial triggered lightning tests for the transmission line were carried out in parallel. During three years since 1996, the experiments have been performed in Mt. Okushishikui near Japan sea for winter thundercloud. The experiments were continued during one month on November in each year. The results were as follows,(1) The corona discharge current measurement was performed at eight arm ends of a test transmission tower which is 60 meters high. The maximum current was more than 500 A which was measured at one arm end on the up pest level. The currents at the lower level were comparatively smaller than the upper level.(2) The average charge of the current from the whole arms of the tower was around 0.1 C/hour under the exposure of thundercloud.(3) The artificial triggered lightning experiment was performed using rocket. First the rocket carries a bobbin from which a nylon line was pulled out and a wire connected follows. The nylon line was used for insulation of wire from the ground. The length of the nylon line was 160m. Thirteen times of triggered lightning struck the transmission line and tower. It is estimated that the lightning strikes to the transmission line and tower take place in the surrounded air with such space charge.(4) Additional seventeen times of triggered lightning were obtained to strike the ground level by means of another triggering methods, and the current wave forms and the energy of lightning discharge channel were measured. And another kinds of observation were successfully performed.(5) The total triggered lightning strikes obtained in these three years were 30 times.