ASME International

Part 7: Measurement of Shaft Power Instruments and Apparatus
 N PTC 19.7

Annotation

OBJECT AND SCOPE

The object of this Supplement is to describe the function, characteristics, advantages, disadvantages, and accuracy of equipment and techniques currently available for the measurement of shaft power of rotating machines.

The scope of the Supplement is limited to descriptive material which will enable a user to select an appropriate system or procedure for his application. It includes criteria for the operating conditions of the equipment whose power is being measured, and instructions for the calibration of apparatus.

Two direct methods of shaft power measurement are described. The reaction torque method utilizes a dynamometer which may supply or absorb shaft power. The other method utilizes a torquemeter which measures torque transmitted between a prime mover and a driven machine.

When direct means of shaft power measurement are impractical, certain indirect methods may be used. Indirect methods measure the power by electrical means or by thermodynamic analysis.

For each method presented, this Supplement describes, insofar as appropriate:

Apparatus and required facilities.

Operating principles and characteristics.

Range and limits.

Accuracy.

Calibration methods.

Necessary precautions.

Sources of error;