Automatic Phase Selection System for Uninterrupted Power Supply

Electrical and Electronics Engineering

This project presents an intelligent automatic phase selection system designed to ensure uninterrupted single-phase power supply from a three-phase system. In many residential, commercial, and industrial applications, phase failure is a common issue that leads to power interruptions and affects the performance of electrical appliances. Traditional manual phase changeover methods are inefficient, time-consuming, and require human intervention. To overcome these limitations, this system introduces an automated solution using a microcontroller-based control mechanism. The system continuously monitors the voltage of all three phases (R, Y, and B) using voltage sensing circuits. An ATMega328 microcontroller analyzes real-time voltage data and determines the health and stability of each phase. Based on intelligent decision logic, the system automatically selects the healthiest available phase. A relay driver circuit (ULN2003) is used to control electromechanical relays, which switch the load to the selected phase without delay. Additionally, the system includes mobile-based monitoring, where switching events and phase conditions are logged and transmitted for real-time observation. This enhances system reliability, safety, and user convenience. The proposed system eliminates manual intervention, reduces downtime, and provides a cost-effective and efficient power management solution. It is suitable for applications in homes, offices, and small industries where continuous power supply is essential.

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