Energy absorption capacity of a 500 kV surge arrester for direct and multiple lightning strokes

Damage to 500 kV surge arresters occurred due to direct and multiple lightning strokes. The present paper initially analyzes the mechanism of how the surge arresters were damaged based on the accident investigative results and evaluates the energy absorption capacity of existing surge arresters by analyzing the energy absorbed when the surge arresters were damaged. Consequently, the damage was confirmed as attributable by the crack of ZnO elements due to the thermal stress sustained when absorbing the energy of direct and multiple lightning strokes. The damage energy was estimated at about 5.4 MJ. Subsequently, based on the lightning observation data according to the lightning location system and the lightning outage rate of transmission lines, the standard lightning-stroke conditions were determined, the required energy absorption capacity of the surge arresters was analyzed and determined to be less than 5.3 MJ. Although the energy absorbed in the above damage cases exceeds this required energy absorption capacity, it is still considered within the variable range of lightning events. Consequently, existing surge arresters have the required energy absorption capacity and the cases involving damage to surge arresters are considered extremely rare.