UHF defect evaluation in gas insulated equipment

Small defects in SF/sub 6/ gas-insulated substations like fixed particles (fixed to conductors or on spacer surfaces) or free moving particles can influence the insulation strength of the insulation system. To determine the risk of such defects on the insulation strength, identification of the PD source is one of the most important steps. In this paper, a method to identify defects based on statistical analysis of frequency spectra is introduced. Finally two examples of risk analysis of defects in GIS are shown.