Degradation-Diagnosis Technology for Surge Protection Device for power line.

It is difficult to diagnose the deterioration of surge protection device (SPD) that protect electrical facilities from surge voltages. The conventional approach is to remove the SPD from the equipment, measure the operation starting voltage with an expensive testing apparatus, and then judge. To simplify this procedure, we investigated the connection between SPD deterioration and leakage current and found that the peak value of the leakage current was closely correlated with deterioration. On the basis of this result, we developed a deterioration diagnosis device that can be easily and safely handled by equipment maintenance personnel without having to remove the SPD.