Resonant grounding networks: A new perspective for the utilization of MOSA with series spark gaps

This paper presents a new appraisal for the utilization of series spark gaps with metal oxide surge arresters aiming at networks with resonant grounding. For these networks, single phase faults can lead to enduring overvoltages on the sound phases, stressing equipments like arresters. Usually, this is not a problem when the network is planned to operate with resonant grounding. But the situation changes when a solidly grounded network is adapted to operate with a resonant grounding. In this case, the natural solution is the replacement of the arresters by equipments with higher rated voltages, implying in higher costs and raising the residual voltage on arresters during a current surge. The utilization of spark gaps allows keeping lower rated voltage arresters as though as avoids the occurrence of high residual overvoltages from the arresters.