Measured efficiency of high efficiency and standard induction motors

An induction motor efficiency test program was undertaken by the North Carolina Alternative Energy Corporation to form an independent basis for recommending energy efficient motors to industry in North Carolina. The test program had two objectives: to compare the efficiencies of new motors of the standard and high-efficiency designs, and to compare the efficiencies of new and rewound motors. Several new motors in the 5-, 10-, and 100-hp sizes were tested. The test results show that for the most part the high-efficiency designs are indeed more efficient than the standard designs at full load and operate closer to their peak efficiency over a wide range of loads than do the standard motors. To evaluate the effect of rewinding on motor efficiency, four of the new motors from the original test were rewound and retested. The results of the efficiency tests showed only a minor degradation in performance after rewinding. Provided are complete descriptions of the tests performed and a discussion of the accuracy of the measurements.<>