Design and Construction of Automatic Transfer Switch using Programmable Logic Controller (PLC)

Erratic power supply owing to the inability of public power supply utilities (PHCN) to meet the populace's demands has necessitated an alternative or emergency source of power supply (such as a generator set or solar system). The problem of seamlessly switching between the backup supply and the alternative sources in the event of a mains source failure is presented by the introduction of these alternate sources of supply. The objective of the design centres on sensing the primary/main source of power supply when available and automatic transfer of load to the available power source using a programmable logic controller. The main design was achieved by the synergetic contribution of automation device: programmable logic controller PLC, SIEMENS LOGO, in this case, responsible for switching operation, three 220v/24v electro-mechanical relays, three 24v/220v relay, three contactors amongst others. The proposed system possesses high efficiency and scalability through extensive simulations between three power sources and hardware implementation.