Improvement in Energy Efficiency of Induction Motors by Means of Voltage Control

It has been estimated that electric motors in the U. S. consume approximately 64% of all the electric energy generated. Also, over the past 12-20 years, the efficiencies of electric motors under 10 kW (~15 hp) have degraded significantly, though the trend toward lower efficiencies appears to be reversing. Very substantial energy savings are possible in lightly loaded induction motors by means of controlling the applied voltage. Tests are conducted on a fractional horse-power motor, and several voltage control arrangements consisting of SCRs are compared in their ability to improve the motor efficiency, and in terms of the amount of harmonic currents generated.