GIS circuit breakers are typically operated by hydraulic, pneumatic, or spring‑actuated mechanisms, while disconnect switches and earthing switches are generally driven by pneumatic, manual, electric, or electric‑spring actuators. In transmission lines, GIS serves both control and protection functions, making it one of the most critical pieces of power transmission and distribution equipment. With advantages such as compact size, minimal footprint, ease of installation and construction, immunity to external environmental conditions, safe and reliable operation, flexible configuration, simple maintenance, and long overhaul intervals, GIS has gradually replaced air‑insulated and oil‑less alternatives. It is now widely deployed in power grids at 72.5 kV and above, particularly gaining widespread adoption in hydropower substations and urban distribution substations. Moreover, GIS has become the preferred choice for ultra‑high‑voltage transmission and transformation equipment. As urban development expands in scale and pace, and in response to the needs of railway infrastructure, GIS is also finding practical applications in the medium‑voltage sector.