On-site Sensitivity Verification for UHF PD Detection in GIS

Abstract

In industry, partial discharge technology related to switchgear has been operational for many years. Partial discharge testing has been conducted on both new high voltage switchgear in the laboratory setup, as well as several older HV installations in the utility grid. The results clearly indicate that partial discharge analysis of HV switchgear is an excellent online tool to assess its dielectric condition. “Dielectric windows” present on existing GIS offer the possibility to pick-up the signals by means of external couplers. In order to check the sensitivity or to prove the possibility to detect a certain PD level, a sensitivity check procedure has been published by Cigre several years ago. This procedure was mainly focusing on new equipment in which internal sensors are being installed in the factory. In this case, it is possible to make comparison tests in the laboratory between the UHF technique and according to the IEC 60270 to get a relation between both readings.For older GIS with PD couplers retrofitted or using external sensors, usually the laboratory step required in this sensitivity check procedure is not possible due to lack of spare parts. In this contribution, a solution to perform the laboratory test on-site is described.