DESIGN AND CONSTRUCTION OF SMART SINGLE-PHASE AUTOMATIC CHANGEOVER SYSTEM FOR DOMESTIC APPLICATIONS

This project presents the design and construction of a single-phase automatic changeover switch (ACS) for domestic applications, incorporating three major features: automatic source transfer, overload protection, and power metering. The system was designed to interface with two power sources, the utility grid and a backup generator, ensuring uninterrupted supply to household loads. The control circuit employed 12V DC relays and timers to execute switching logic, while 50A contactors handled the power circuit, thereby providing electrical isolation between control and load operations. A digital energy meter was integrated to display real-time voltage, current, and power consumption. The constructed prototype was subjected to a series of performance evaluations. The automatic switching functionality test confirmed reliable transfer of load to the generator during simulated grid failure and a seamless retransfer upon restoration. The prioritization logic consistently favored the grid supply over the generator, in line with the design intent. Overload testing showed that the protective circuit breaker responded within 3.5 seconds at 120% of rated load, while a short-circuit condition triggered immediate disconnection. Metering accuracy tests revealed less than 2.5% error across varying load conditions, validating the reliability of the monitoring system. The results demonstrate that the system successfully met its objectives by ensuring continuity of supply, protecting against overloads, and providing accurate power monitoring. It is concluded that the ACS is suitable for domestic applications, while future improvements such as microcontroller-based control, three-phase compatibility, and IoT integration are recommended.