Energy efficiency electric Premium motor-driven systems

The declining resources combined with environmental global warming concerns and increasing energy prices make energy efficiency a crucial objective. Furthermore, improving energy efficiency is often the cheapest, fastest and most environmentally friendly way to meet the world´s energy needs. It´s significant to notice that to date, there is no universally accepted test protocol and no agreement that allows the determination of system efficiency (motor and drive) at any given operating load and frequency. The main objective of this research was to determine motor efficiencies under variable loads and variable speeds, induced by a Variable Frequency Drive VFD controller. So, when computing efficiency, it is matter-of-fact to provide separately motor efficiency feed by a VFD or across the line, VFD efficiency, and system (VFD + motor) efficiency. The obtained results show that maximum NEMA Premium motor efficiency is somewhere between 60% and 80% of rated load for different frequencies, and tends to decrease substantially below about 40% load, while experienced overloaded motors induce efficiency reduction. Drive efficiency peaks somewhere beginning from 40% rated load, and below 20% load, the drive efficiency drops abruptly, while experienced overloaded drives don´t induce efficiency reduction.