Induction motors are widely used in industrial applications due to their favorable operating characteristics and ease of speed control. However, they exhibit a relatively low power factor caused by a high demand for inductive reactive power. This study aims to improve the power factor of a three-phase slip-ring induction motor through reactive power compensation using a capacitor bank. Tests were conducted at load conditions of 1.6 Nm and 2.1 Nm, utilizing a capacitor bank with eight activation levels and a total capacitance range of 0–30 μF. The results indicate that without compensation, the power factor was 0.29 and 0.33 for the respective load conditions. Optimal compensation was achieved using a combination of switches 2, 3, and 4 (total capacitance of 28 μF), which improved the power factor to 0.83 at a 1.6 Nm load and 0.89 at a 2.1 Nm load, while simultaneously reducing the line current to near-minimum values. Conversely, activating all switches (30 μF capacitance) resulted in over-compensation, causing the load characteristics to become capacitive; consequently, the power factor dropped to 0.50 and 0.43, accompanied by an increase in line current. The findings demonstrate that selecting the appropriate capacitor bank capacity can effectively improve the power factor and reduce line current in slip-ring induction motors.
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