Design and implementation of a 3-phase intelligent changeover system with automatic generator start and stop control

This paper presents the design and implementation of a Three (3)-phase intelligent power change over system with automatic generator run and stop control. The system uses phase sensors to monitor the voltage in each phase. The voltages monitored by the phase sensors are then fed into the analog to digital converters (ADCs) embedded inside the PIC microcontroller for analysis. The PIC microcontroller is in charge of all the control operation in the system and takes intelligent decisions based on the analysis. The decisions of the microcontroller are used to control the operation of the power circuit, which has three contactors, through relays. The phase sensors also help the system to sense any abnormal condition in any of the phases which may be low voltages, high voltages or blackouts. The system automatically disconnects the load from the mains source when there is any abnormality and transfers it to the standby generator source. It then starts the standby generator and continues to monitor the mains for the restoration of power. Once power is restored and the quality of power in the phases is perfect, the system automatically transfers the load to the mains source and stops the standby generator. At each point in time, the voltage levels of each of the phases of both the mains and the generator outputs are displayed on the 16 by 4 line LCD display.