The rated horsepower for centrifugal-compressor drivers should be a minimum of 110% of the maximum horsepower required for any specified operating point. For motor drivers, it is necessary that the motor be carefully matched to the compressor, and items reviewed such as:
• motor speed-torque characteristics,
• accelerating-torque requirements of the compressor, and
• motor supply voltage during acceleration.
(See the Motor section of the Driver Manual.) Steam turbines should have a maximum continuous speed 105% of rated compressor speed.
Driver requirements are further detailed in API 617. API Standards 611 and 612 cover general purpose and special purpose steam turbines.