Modified Efficiency Estimation Tool for Three-Phase Induction Motors

This article presents a modified version of novel algorithms the authors previously proposed to help North America electric motor service centers to evaluate their repaired, rewound, or any existing motors for efficiency. Due to the dependency of the algorithms on a large 60 Hz induction motor database to produce reliable and accurate results, a software was needed and developed to incorporate both the algorithms and the data to create a useful single affordable tool for the North America electric motor repair industry. To eliminate the need for the software, and allow an open-source implementation, the direct dependency of the efficiency algorithms on the motor test data are eliminated in this paper. This allows the two techniques presented here to be used directly by engineers in the motor repair industry in North America. To achieve this goal, modifications to the two original algorithms are required and proposed in this paper. The modifications include the implementation of a new stray-load loss formula and the IEEE Std 112 hot temperature formula. The modified algorithms are validated by testing 28 new and aged, small- and medium-sized induction motors in the range of 1-500 hp. The modified techniques demonstrate a high level of accuracy.