This standard applies to electric power systems in stationary generating stations that provide electric power to the power system. Nomenclature is included for the following interrelated systems: 1) Generating unit power system 2) Generating unit auxiliaries power system 3) Station auxiliaries power system 4) Generating unit dc auxiliaries power system 5) Station dc auxiliaries power system This standard is limited to the preceding power systems and does not include nomenclature for instrumentation, controls, or auxiliaries.