Optimal Rating of an Induction Motor for a Given Load Diagram

An optimally rated induction motor is defined as one which satisfies all the engineering requirements and also yields a minimum cost over it´s operating lifetime. This paper develops a generalized cost function which finds the optimal rating of a motor for a given deterministic load diagram. The results of a case study show that the most economic motor will be over rated from an engineering point of view, because the high price of electricity forces the choice to larger motors with smaller losses.