The requirements for synchronous machines with excitation windings are covered by three American National Standards as follows: American National Standard General Requirements for Synchronous Machines, C50.10-1977. American National Standard Requirements for Cylindrical Rotor Synchronous Generators, C50.13-1977. American National Standard Requirements for Combustion Gas Turbine Driven Synchronous Generators, C50.14-1977. This standard contains general requirements and definitions applicable to all types of 60 Hz synchronous machines except fractional horsepower motors. Specific requirements for cylindrical rotor synchronous generators and combustion gas turbine driven synchronous generators will be found in American National Standards C50.13-1977 and C50.14-1977.