Condition for Maximum Efficiency of Three-Phase Induction Motors

Three-phase induction motors are utilized in a great variety of industrial applications. Their operating points must be carefully designed when putting them into service. They are often set to run close to their rated horsepowers to gain a good running efficiency. In this paper, a quadratic equation is formulated to solve the motor’s operating speed in which a condition for maximum efficiency does occur. A standard equivalent-circuit model of the induction motor is employed for validation. The precise value of speed obtained from the proposed method can assist users to design the right operating conditions for energy-saving potential.