Deterioration Characteristics of Insulating Spacer Model toward Repeating Impulse Voltage

In order to discuss the UHV GIS test voltage, the deterioration characteristics of GIS insulating spacer model was studied by repeating lightning or switching impulse voltage. Deterioration factor in which indicates the decrease of lightning or switching impulse breakdown voltage up to 1000 times applications was found to be 35.7/45.5. And, the relation between partial discharge inception voltage and breakdown voltage was studied after 1000 times impulse application. As the result, it was found that partial discharge inception voltage was increased in spite of breakdown voltage decrease due to the impulse voltage. Moreover, in order to make clear the deterioration phenomenon, breakdown characteristics of models with various boundary conditions between electrode and epoxy resin was studied and the relation between the boundary conditions. Furthermore micro-discharge was also studied. From the investigated results, the deterioration by repeating voltage was caused by micro-discharge due to electric field intensification on micro protrusion of the electrode surface.