Design And Construction Of An Automatic Single Phase Transfer Switch

ABSTRACT

This project presents the design and construction of a microcontroller based Automatic Transfer Switch (ATS) for a single phase system. The ATS, which is based on a switch gear control system, gives a functional system that provides an automatic switching of power supply between a primary source (public utility) and a secondary power source (generator). The methods employed in designing the ATS involve the use of switching and power relays, Atmega8 microcontroller, diodes, resistors, L 7805 voltage regulator, optocouplers, a buzzer alarm, NPN transistors, and an LCD which indicates which power source is available. The microcontroller [receives a regulated 5v DC from the 12v battery which is attached to the generator and with the aid of the optocoupler senses the public utility power supply to initiate the 30A power relay which is driven by a transistor to initiate output load. An interruption in the supply from the public utility initiates generator staii up and this is achieved using switching relays driven by NPN transistors for the kick and staii position of the secondary power supply (generator). This signal is sensed by the microcontroller through the optocoupler to initiate the 30A power relay which gives the output for loading, a failure in this operation initiates an alarm by the buzzer. This entire process when achieved is displayed on the liquefied crystal display. This project performs perfectly with a functional generator possessing an automatic choking system when tested