Lightning-caused distribution transformer outages on a Florida distribution system

The data obtained from the Electric Power Research Institute (EPRI) Research Project (RP) 2542-1 on the characteristics of lightning surges on distribution lines are presented. This project was conducted to measure the lightning-caused currents and voltages that occur on distribution lines and to quantify the distribution system damage that occurs because of lightning. During the 3 yr data-gathering period, 2448 distribution transformers were monitored. The estimated lightning-caused transformer failure rate was 0.25%, and the estimated lightning-caused transformer fuse operating rate was 0.43%. Although these data are useful in the operation of distribution systems, further reducing the transformer failure rate will require that the exact failure mechanisms be established. It is noted that the research to determine the failure mechanisms will require a long measuring period and thus can be expected to be expensive