Gapped Arresters Revisited: A Solution to Cascade Coordination

This paper provides a brief perspective on how the coordination of cascaded surge-protective devices (SPDs) has become an issue. We propose an approach where the 'ancient' technology of gapped arresters may well be the answer to the dilemma of the incompatibility of a service-entrance SPD having relatively high limiting voltage with the proliferation of built-in or plug-in SPDs having relatively low limiting voltage inside the buildings. The solution involves providing a gapped arrester at the service entrance and gapless SPDs inside the building. An example is given of such a combination, with experimental verification of the proposed solution and computer modeling that allows a parametric evaluation of the significant factors in any candidate combination of SPDs.