2015 Volume 135 Issue 9 Pages 533-537
High-voltage equipment like gas-insulated switchgear (GIS) has been widely applied since the late 1960's thanks to its compactness and high reliability. However, the equipment over 40-year-old will be increasing from now on, and lower reliability of the equipment due to the in-service ageing and retirement of engineers/technicians with the equipment know-how are now in great concern. This brochure reports mainly the following three study items. Firstly, the number of the equipment (GIS) installed up to now was surveyed, and the average major/minor failure rates were evaluated from the viewpoints of ageing of GIS. Secondly, the transition of GIS components/construction and their actual operation/maintenance were reviewed. Lastly, the latest techniques were summarized in terms of monitoring/diagnostics for appropriate GIS renovation, GIS lifetime assessment, and lifetime extension of aged GIS.