A New Approach to Motors Efficiency Estimation in an Industrial Energy Management Program

摘要

Efficiency in motors has always played an important role in energy analysis in industry. Their importance is dramatic as motors account for about 50% to 60% of the energy used by industries. Particularly considering that energy costs generate a high impact over profitability in the industry sector. However, several studies have demonstrated how different can be the approach and subsequently the results from energy analysis, depending on how the efficiency motor is estimated. Actually, some changes have been identified in European standards (IEC 34-2) in order to improve the accuracy level obtained, requested and finally offered to the industry within efficiencies motor standards. Meanwhile, other studies have demonstrated the convenience of American standards (IEEE 112 and National Electric Manufacturers Association - NEMA) related to actual values of efficiencies, and compared with other standards available and generally accepted world-wide. Due to the high relevance of motor efficiency estimation over energy analysis, this work includes a new pragmatic approach, based on previous analysis related to the most accurate standard, generally accepted in the industry. It develops a way of estimating the efficiency of the motor according to its size (in hp) and its rpm. The procedure shows to give very accurate efficiency value for that motor (under certain standard conditions), required for motors energy management analysis. One of the main advantages offered by this approach is that it gives a reliable and quick estimation of motors efficiencies, available for the analysts with little data gathering. Most importantly, the results are in excellent agreement with American standards references. In addition, we present with our findings, and using extrapolation techniques, 3-dimensional efficiencies surfaces to show and justify, the best working conditions.