This standard establishes ratings and requirements for planning@ design@ testing@ installation@ and operation of gas-insulated substations for alternating-current applications 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.