Evaluation of the failure probability for gapless metal oxide arresters

The energy absorption of surge arresters on power systems due to lightning strokes is evaluated using the Electromagnetic Transients Program (EMTP). On the basis of this study, a selection criteria is given in order to determinate the optimal arrester for a location. The improvement is applied to a practical example. The analysis shows that the failure probability of an arrester depends on its energy capability, the rated voltage and the power system configuration. The discharge energy and the critical current producing damage in the arrester are calculated, which permit the failure probability to be determined.