Abstract: An important requirement of electric power distribution systems is the need for automatic operation. In particular, the rapid and reliable transfer of the system from one power source to another during certain system events is important to achieving the reliability goals for such systems and the facility serves. In the existing system, use of four switches to demonstrate the corresponding failure of that power supply has been attempted.  By pressing any one of the switches, absence of that particular source can be found out. The switches are connected as input signals to Programmable Logic Controller. In this system the PLC is used. The relay driver IC collects output of PLC, which adjusts relay to maintain continuous supply to the load. This work mainly focuses on the automation. Future add-ons to the product can make it as a complete independent working model .An attempt has been made to  study  the use of PLC  to get  uninterrupted power supply without the need of human intervention, saving non-conventional energy and reduce the overall cost as it saves the electricity bill tariffs and the maintenance cost is less as the solar cells lasts long .Use of non-conventional energy sources these days is a transformation in itself. 

Keywords: PLC, Solar Energy, Auto Power Supply, Critical Load, Automation

| DOI: 10.17148/IJIREEICE.2019.7406