Simple and Accurate Algorithm for Small- and Medium-Sized Three-Phase IM Efficiency Estimation Based on No-Load Tests

This paper presents a simple and accurate industrial tool that can be used to estimate the full-load efficiency of three-phase induction motors based on no-load tests. The objective of this research work is to eliminate the need for the expensive dynamometer test, which is available only in well-equipped laboratories and provide electric motor service centers in North America with a user-friendly tool that enables the centers to have their rewound, refurbished, or any existing motors evaluated for efficiency prior to delivery to customers. The proposed technique utilizes a test data of 129 motors, ranging from 1 to 500 hp, tested in Hydro-Québec Laboratory as per IEEE Std. 112B and CAN/CSA C390 standards procedures. The technique also utilizes a recently proposed stray-load loss formula. The algorithm is validated by recalculating the efficiency of the 195 motors by using the proposed technique. The results show an acceptable degree of accuracy. Error analysis study is conducted to examine the level of uncertainty within the accuracy of the proposed algorithm. The outcome of the study completely supports the algorithm. A spreadsheet-based software is designed to turn the algorithm into a practical user-friendly industrial tool.