This standard can be used for performance testing of combined cycle steam turbines and combined cycle cogeneration steam turbines with or without supplementary combustion. Within these unit categories, this standard applies to condensing and non-condensing steam turbines, steam turbines with and without reheat, and steam turbines with admission or extraction steam. Currently, the diversity of thermodynamic cycles poses a challenge in writing a standard that applies to all cycle configurations. For nuclear power or thermal power feed water recuperation cycle steam turbine testing, ASME PTC 6 should be used. This standard is only applicable to thermal performance testing of combined cycle steam turbines using steam as the working fluid. This standard provides testing and calculation methods for turbine generator output performance corrected to reference operating conditions to measure the overall performance of the turbine. This standard contains the rules and procedures for test implementation and result reporting, including requirements for preparatory test arrangements, test techniques, instrumentation, measurement methods, test results and uncertainty calculation methods.