Design And Construction of an Automatic Phase Selector

Design And Construction of an Automatic Phase SelectorIshaq Sonpawuni¹¹Railway and Allied Engineering Programmes, School of Railways and Infrastructure Development, University of Mines and Technology, Tarkwa, GhanaCorresponding author ishaqsonpawuni@gmail.com | Journal: African Electrical Engineering Journal | Manuscript ID: PARJ-2026-7627A72 | DOI: 10.5281/zenodo.20948674AbstractReliable supply to single-phase loads remains a practical challenge in many residential, commercial and light-industrial settings where three utility phases are available but individual phases are frequently affected by undervoltage, interruption or imbalance. Manual phase changeover is still widely used in such contexts, yet it exposes users to avoidable downtime, switching delay, contact wear and safety risks. This study presents a low-cost automatic phase selector that senses three input phases, ranks the available phases according to programmed priority and voltage availability, and connects the load to the best available line through a relay/TIP41 switching stage. The implemented system used an ATmega328P-PU microcontroller, three voltage-sensing channels, transformer-isolated low-voltage inputs, rect