This Standard applies to those parts of the electric systems in stationary land-based nuclear power generating stations that provide electric power to the Class IE electric equipment. The electric systems included are comprised of the following interrelated systems: (a) alternating-current power systems, (b) direct-current power systems, (c) vital instrumentation and control power systems. These systems consist of power supplies (e.g., connections to the station switchyard, generating units, batteries), distribution equipment and components (e.g., transformers, switchgear, bus, cable, battery chargers, inverters), and instrumentation and controls (e.g., relays, meters, switches, control devices). This Standard does not apply to the station generator, generator buses, step-up and auxiliary transformers, switchyard, the transmission lines, and the transmission network