DESIGN AND IMPLEMENTATION OF AN AUTOMATIC PHASE SELECTOR FOR RELIABLE SINGLE-PHASE LOAD OPERATION FROM THREE-PHASE SUPPLY

Abstract

Unstable power supply and frequent phase failure remain common challenges in industrial, commercial, and residential settings. In threephase systems, the absence of one or more phases often disrupts appliances and interrupts daily operations. To address this issue, the present work focuses on the design and implementation of an automatic active phase selector that ensures uninterrupted single-phase load operation. The system employs an Arduino microcontroller to continuously monitor the status of all three phases. Upon detecting a live phase, the controller activates a relay—driven by a transistor—to connect the load to the available phase. If multiple phases are active, the system defaults to Phase I for load connection. An LCD module provides real-time phase condition updates, with contrast control for ease of display. The hardware is powered by a regulated 12V, 500mA supply, incorporating a 7805 voltage regulator and a bridge-type rectifier to stabilize output from a 230V/12V step-down transformer. This design ensures seamless switching, reduces downtime, and enhances reliability in environments where power instability is prevalent.