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WG B3.25 SF6 gas analysis for AIS, GIS and MTS condition assessment

Experience has shown that High Voltage gas insulated switchgear can have a useful life considerably longer than initially envisaged.  Therefore condition assessment of the switchgear and the correct interpretation of the results have increasingly become more important. A critical decision is the selection of the right moment for any intervention, i.e. to prevent a violent failure and simultaneously to avoid unnecessary internal inspections of the equipment (from outage avoidance as well as environmental impact points of view).  The analysis of the SF6 or mixed gas composition is a very common diagnostic method used for gas insulated switchgear (GIS) as well as for any other equipment filled with SF6 or mixed gas (live tank CB, dead tank CB, MTS, instrument transformers, etc.). Notwithstanding the considerable amount of analysis of SF6 undertaken the interpretation of the results is not standardized and frequently the recommended limits for contaminants vary depending on who undertakes the analysis. The WG aims to address these issues.