Energy efficiency of hoisting motors

This study concentrates on energy efficiency of hoisting motors in industrial cranes. Motors in the scope are of three-phase cage-induction type and specially designed for intermittent duty S3. The main focus is on converter-fed motors. For a motor of certain rated power dimensions and rotor material are varied and electrical efficiency as a function of load is calculated. Energy consumptions for typical load spectra and operating hours are determined and compared to the energy consumptions of material production. It is shown that for light loads and infrequent usage manufacturing phase constitutes a significant part of the total energy consumption. Thus, increasing the efficiency of a motor may not provide notable energy savings. However, at high loads and operating hours better efficiency decreases the life-cycle energy consumption of an intermittent duty motor as well.