The requirements in this standard apply to all 50 Hz and 60 Hz, two-pole and four-pole, cylindrical-rotor synchronous generators driven by steam turbines and/or by combustion gas turbines. The drive may be direct or through a gearbox or other device that permits different speeds for the turbine and the generator. The generators covered by this standard are to have rated outputs of 10 MVA and above. Cylindrical-rotor, two-pole and four-pole generators below this rating are generally covered by NEMA MG 1-2003 [B18].1 The purpose of this revision is to: 1) update the document to current industry standards and criteria, 2) evaluate this document with IEC 34-1 and 34-3 and seek compatibility where it can be found, thus bringing the documents in closer harmonization, and 3) combine the scopes of C50.14 and C50.15 into this one document addressing cylinderical rotor synchronous generators. Revision Standard - Superseded. The requirements in this standard are applied to 50 Hz and 60 Hz, two-pole and four-pole, cylindrical-rotor synchronous generators driven by steam turbines and/or by combustion gas turbines. The drive may be direct or through a gearbox or other device that permits different speeds for the turbine and the generator. The generators covered by this standard are to have rated outputs of 10 MVA and above.