While complexity in national and regional standards exists, we are beginning to see a consolidation around three levels as defined by the International Electro-technical Commission (IEC). These are IE1 (Standard Efficiency), IE2 (High Efficiency) and IE3 (Premium Efficiency). There is around 3-4% energy efficiency difference between IE1 and IE3 standard motors, but the differences, and the absolute level of efficiency, depend on the output of the motor relative to its rating (see Figure 118).
IE3 is a new classification, but one that has been recognised by NEMA in the United States for some time. It generally applies to large, industrial motors. In Europe, this grade of motor will only become mandatory in some applications in 2017. In the United States, the required introduction date is from 2015 for larger motors, 2017 for smaller ones.
