Effect of Capacitor Capacitance on the Power Factor Performance of Single-Phase Induction Motors

Abstract

This study experimentally investigates the effect of capacitor capacitance variation on the power factor and operating characteristics of a single-phase induction motor under no-load conditions. Single-phase induction motors are widely used in residential and light industrial applications; however, their inductive nature often results in a low power factor and increased current consumption. To address this issue, capacitive compensation was applied by installing capacitors with different capacitance values (4 µF, 6 µF, 12 µF, and 18 µF) in the auxiliary winding circuit. The experimental setup was implemented in a controlled laboratory environment, and key parameters including power factor, stator current, electrical power consumption, starting voltage, and rotational speed were measured for each capacitance value. The results show that capacitor capacitance significantly influences motor performance. A capacitance of 4 µF provides the most favorable operating condition, yielding the highest power factor while maintaining relatively low current and power consumption. Increasing the capacitance beyond this value leads to excessive leading compensation, which is associated with higher current draw, increased power consumption, and reduced rotational speed. These findings indicate that appropriate capacitor selection is critical for achieving effective power factor improvement without compromising energy efficiency. The outcomes of this study provide practical guidance for capacitor sizing in single-phase induction motor applications and contribute to a better understanding of reactive power compensation under no-load operating conditions.