低圧配電機器の交流アークによる雷被害発生確率の推定

抄録

For construction of low-voltage power distribution systems, it is important to have correct informations on the probability of failures by the lightning in order to meet the requirement for high reliability of these systems.
The burn-out of low-voltage distribution equipment is triggered by flashover due to the lightning overvoltage, which is followed by the arc discharge current at the commercial frequency voltage. The arc characteristics were investigated by superimposing the lightning impulse voltage across terminals of the low-voltage distribution equipment connected to the commercial frequency power supply in order to reproduce these events on an experimental basis. As a result, it was found that the arc characteristics were affected by a number of factors.
The probability of flashover occurence on low-voltage distribution equipment is determined based on the frequency distribution data of lightning overvoltage occurence obtained by the surge counters monitoring on actual distribution lines. Then, the probability distribution of arc currents is established by application of the above experimental equation on arc characteristics. Finally, the method for evaluation of damages by the lightning to low-voltage distribution equipment on actual lines was investigated with the frequency of lightning strokes and the configuration of low-voltage distribution systems taken into consideration.