Design of an Automatic Power Factor Correction System for Industrial Loads in Nnewi, Anambra State

This project designs an automatic power factor correction system for three-phase industrial loads in Nnewi, Anambra State, South East Nigeria. Nnewi is Nigeria's foremost industrial hub for auto parts manufacturing and related industries, where large induction motors, welding machines, and transformers create lagging power factors that result in reactive power demand charges from electricity suppliers, increased line currents, and reduced distribution system capacity. The automatic power factor correction system uses a power factor measurement module based on zero-crossing detection of voltage and current waveforms to compute the real-time displacement power factor. An ATmega32 microcontroller interprets the measured power factor and switches capacitor banks in a binary-weighted configuration (5 kVAr, 10 kVAr, 20 kVAr stages) using contactors to provide 35 discrete reactive power compensation levels between 5 and 35 kVAr. The switching logic maintains the power factor within the target band of 0.95 to 1.00 to satisfy both tariff requirements and network efficiency. Over-voltage protection prevents capacitor switching during high voltage events. A prototype was tested on the electrical distribution board of a medium-scale auto parts manufacturing plant in Nnewi. The system successfully raised the average power factor from 0.72 to 0.97, reducing reactive power demand charges by an estimated 32 percent monthly. The project recommends integration of a harmonic filter into the capacitor bank design to prevent resonance amplification of existing harmonic voltages. Keywords: power factor correction, capacitor bank, industrial load, reactive power, Nnewi.