INFLUENCE OF ELECTRICAL PARAMETERS VARIATIONS ON STANDARD THREE-PHASE ASYNCHRONOUS MOTORS EFFICIENCY

This paper analyzes the sensitivity of the electromagnetical efficiency with respect to the electrical parameter variations for a series of standard three-phase asynchronous motors. At first, the electromagnetical efficiency of asynchronous motors is determined by referring to the electrical equivalent circuit of the motor; iron and copper losses are only considered. Then, the expression of the ratios between the p.u. variation of the efficiency and the p.u. variation of each electrical parameter are given either for fixed speeds or for fixed effective values of the stator phase current. Besides the p.u. variations of the efficiency are related to the contemporaneous p.u. variations of all electrical parameters by means of a simple relation.