抄録
In order to study lightning problems of low-voltage power distribution lines, lightning overvoltage waveform were observed inside the house of customers. And the cause of lightning overvoltages was examined from observation of striking points by still cameras. Lightning overvoltages of 62 waveforms were recorded by observation for about four years. Observed waveforms can be classified into three types of single polarity (positive or negative), both polarity (which changes from positive to negative or negative to positive), and pulsive waveform. The causes of these lightning overvoltages which were estimated from striking points are shown as follows:
(1) Induced lightning overvoltages on low-voltage distribution lines.
(2) Electric potential rise due to discharge of surge arresters or current of overhead ground wire.
(3) Shift of lightning overvoltages from high-voltage side of transformer to low-voltage side, which due to electro-magnetic induction.
