This part of IEC 60034 applies to three-phase synchronous generators, having rated outputs of 10 MVA and above driven by steam turbines or combustion gas turbines. It supplements the basic requirements for rotating machines given in IEC 60034-1. Common requirements are prescribed together with specific requirements for air, for hydrogen or for liquid cooled synchronous generators. This part of IEC 60034 also gives the precautions to be taken when using hydrogen cooled generators including: – rotating exciters driven by synchronous generators; – auxiliary equipment needed for operating the generators; – parts of the building where hydrogen might accumulate. NOTE 1 These requirements also apply to a synchronous generator driven by both a steam turbine and a combustion gas turbine as part of a single shaft combined cycle unit. NOTE 2 These requirements do not apply to synchronous generators driven by water (hydraulic) turbine or wind turbine. NOTE 3 The precautions to be taken when using hydrogen are valid for all cases where hydrogen is used as a coolant.