1991 Volume 111 Issue 1 Pages 76-84
Recentry, according to the trend that utilization of electricity expands to wider area, effects of outages by lightning on transmission lines become a problem and the cost of electricity transmission tends to go up by anti-lightning measures. This presents growing necessity of more reasonable design of transmission lines. To realize reasonable insulation design, it is necessary to know accurate regional distribution of the lightning incidence. So far, very few were reported as to the regional distribution of trip-out rates of transmission lines.
This paper describes the regional distribution of the lightning trip-out rates of transmission lines in CHUBU AREA. The degree of the lightning trip-out rate of transmission lines in a certain sub area is proposed to be expressed by two indexes. The ground flash density of lightning is also given from these indexes.
Newly introduced Indexes are as follows, lightning trip-out index, Ai, which is given by dividing trip-out rate in a certain sub area by the trip-out rate in whole CHUBU AREA.
Total index, A0, is given by modifying Ai by taking the line length into account.
Total index (A0) shows good correlation with counts of CIGRE lightning flash counters, but it shows very poor correlation with IKL values.
The ground flash density of lightning (N-value) is also given from these indexes. These indexes would be effective to achieve resonable design of transmission lines.