Overview of Long-Term Compatibility and Ageing Tests for Materials Used in High-Voltage Gas Insulated Switchgear

Gas-insulated switchgear (GIS) systems are designed for service lifetimes of several decades while experience from SF6 systems has shown reliable operation for more than 40 years. The introduction of eco-friendly insulating gases, particularly C4F7N mixtures, for transmission applications, requires assessing the long-term compatibility between the gas and the GIS materials. Materials such as epoxy resins, elastomers, metals, and polymers when exposed to the insulating gas, may lead to the decomposition of the gas, material degradation, and reduced equipment performance. At present, no dedicated standards exist for conducting compatibility tests with fluorinated insulating gases. This work reviews the existing standards, technical guides, and published literature to support the selection of…