Experience with PD measurements in GIS maintenance concept

Since the early nineties, ultra-high-frequency (UHF) partial discharge (PD) measurements are being applied to SF
₆
gas-insulated equipment. Over the years, PD measurements revealed the presence of some insulation defects in the 380 kV GIS. The measuring results have been compared to laboratory experiments. Moreover, locating was possible as well. Cigre TF D1.03.09 has been working on a risk-assessment procedure to assess the risk for a failure for insulation defects, based on PD measurements. So this procedure is only applicable to insulation defects that give detectable PD activity. The paper will show examples of the application of this risk assessment method on the different detected PD sources. Finally the actions initiated by the DSO/TSO for these analyzed insulation defects will be described.