This standard establishes ratings and requirements for planning, design, testing, installation, and operation of gas-insulated substations for alternating-current applications for above 52 kV. Typical installations are assemblies of specialized devices such as circuit breakers, switches, bushings, buses, instrument transformers, cable terminations, instrumentation and controls, and the gas-insulating system. It does not include certain items that may be directly connected to gas-insulated substations, such as power transformers and protective relaying. This standard does not apply to gas-insulated transmission lines.