How to Choose Electric Motor for Adjustable Speed Drive (ASD)

Electric motor drives according international standard IEC 60034-1 are divided in ten duty types, from S1 to S10. This paper has purpose to make analysis for the S8, S9 and S10 duty types, which are with adjustable speed drives (ASD). The goal of this paper is to discuss methods for speed control of induction motors (IM) and consumption of total electric energy. By more examples it is presented that consumption of non active energy is not negligible. So, for choice of motor for ASD is proposed additional diagram regarding consumption of non active energy.