Lightning-caused distribution outages

Two rural distribution systems in Ontario, Canada were instrumented to study the relations between lightning events and power system disturbances. Strong time-of-day and time-of-year trends were found in the momentary operation history and component damage rates over four years of study. Implications for the entire Hydro-One Network design philosophy have been drawn from recent advances in the computation of induced overvoltages above lossy earth for overhead lines, inside lossy earth for cables and into two-layer soil for ground electrodes.