Determination of Motor Efficiency and Losses MG 112541

Efficiency and losses shall be determined in accordance with IEEE Std 112 Standard Test Procedures for Polyphase I nduction Motors and Generators*. The efficiency shall be determined at rated output, voltage, and frequency.

Unless otherwise specified, horizontal polyphase squirrel-cage medium motors rated 1 to 125 horsepower shall be tested by dynamometer (Method B) as described in par. 5.2.2.4 of IEEE Std 112. Motor efficiency shall be calculated using MG 1-12.57 in lieu of Form E of IEEE Std 112. Vertical motors in this horsepower range shall also be tested by Method B if bearing construction permits; otherwise they shall be tested by segregated losses (Method E) as described in par. 5.2.3.1 of IEEE Std 112, including direct measurement of stray-load loss.

The following losses shall be included in determining the efficiency:

1. Stator I2R.

4. Stray load loss.

5. Friction & windage loss.1

6. Brush contact loss of wound-rotor machines

Power required for auxiliary items, such as external pumps or fans, that are necessary for the operation of the motor shall be stated separately.

In determining I2R losses, the resistance of each winding shall be corrected in a temperature equal to an

Nominal Minimum

Efficiency Efficiency

0 0

Post a comment