Surge Arrester Protection and Very Fast Surges

The results of this paper suggest that surge arrester protection may not be adequate for very fast rates of rise of lightning currents even considering insulation strength greater than choppedwave. Additionally, it is shown that prediction of the magnitude and front time of the peak overvoltage is a complex function of lead length, arrester model, lead impedances, transformer model, and system voltage. It is suggested that very fast surges could be the source of unexplained transformer failures and that more field data is required.