Design and Implementation of an Automated Power Factor Correction System Using Capacitor Banks

Supriya Jamdar

Abstract: In alternating current (AC) power systems, the effective utilization of electrical energy is directly dependent on the power factor of the system. Low power factor, normally due to inductive loads like motors, transformers, and lighting ballasts, causes high demand for current, which translates into high losses in transmission and distribution lines, voltage drops, low system capacity, and increased electricity bills. To overcome these challenges, the current paper discusses the design, development, and verification of an automatic power factor correction (APFC) system with a microcontroller-based controller unit and a step wise capacitor bank. The system detects real-time voltage and current waveforms via sensing circuits and calculates the phase angle difference to decide the power factor. According to the measured power factor, the microcontroller dynamically switches on or off capacitors to provide the necessary leading reactive power, thus compensating the lagging component caused by inductive loads. The system is implemented using low-cost, easily available components such as a current transformer (CT), potential transformer (PT), zero-crossing detectors, a relay module, and a bank of shunt capacitors. Simulation and experimental confirmation were carried out under different loading conditions to test system performance. The findings exhibit a notable increase in power factor-from levels as low as 0.72 to as high as 0.97-along with line current reduction and improved power quality. Economic assessment also shows substantial annual savings and a brief payback period on investment. The ease, scalability, and efficiency of the system render it appropriate for residential, commercial, and small-scale industrial applications, leading to more sustainable energy consumption habits.

Keywords: Power Factor Correction, Capacitor Bank, Re active Power, Microcontroller, Power Quality, Energy Efficiency, Inductive Load Compensation, Automated Control