Optimization of Three-Phase Induction Motor Design Part II: The Efficiency and Cost of an Optimal Design

With the continuing increase of the cost of electrical energy, motor manufacturers and consumers became increasingly concerned with the energy conservation available from highly efficient electrical motors. Motor cost and efficiency are interrelated; therefore, the effect of motor cost on the maximum obtainable efficiency is of interest both to the motor manufacturer and to the consumer. The relation between the power factor and the maximum efficiency of a motor is another aspect of energy conservation. The optimal motor design, with respect to the maximum efficiency, and with respect to the minimum motor cost (by means of a mathematical optimization method described in Part I), was used in Part II to investigate the above-mentioned motor relations. Three motor-cost functions were investigated: production cost, capitalized cost, and annual cost. The motor that was used in the study was a 100 hp, three-phase, squirrel-cage induction motor.