Measurement of Shaft Power

This Document specifies the function, characteristics, advantages, disadvantages, and accuracy of equipment and techniques currently available for the measurement of shaft power of rotating machines. Two direct methods of shift power measurement are described. The reaction torque method utilizes a dynamometer which may supply or absorb shaft power. The other method utilizes a torque meter which measures torque transmitted between a prime mover and a driven machine. There are three general methods available for measurement of rotational speed: (a) Devices which display, indicate, or record a number of revolutions within a known time interval; (b) Devices which display, indicate, or record time averaged rotational speed; and (c) Devices which continuously record instantaneous angular velocity.  Operating instructions for specific measurement apparatus are outside the scope of this Standard.