An Improved Microcontroller-Based Automatic Three-Phase Analyzer and Selector

Automatic selection and change-over systems have been developed to reduce the risks involved in manual changeover process. While some of the designs switch to any available phase, others switch to the phase with maximum voltage, regardless of the value of the supplied voltage. Other designs which consider the need to avoid both undesirable voltages make the selection range fixed in the code which controls the switching mechanism, thereby not allowing the flexibility in changing the range for switching to meet environmental needs. This work seeks to design an improved microcontroller-based automatic three-phase analyzer and selector with a keypad for setting the switching range for switching. The analysis was achieved by developing a C++ program using the Arduino Integrated Development Environment (IDE) and simulating the system with Proteus Professional Application. The system includes the phase sensing unit, the processing unit and the switching unit. Serial monitor results show that voltages from all three phases may not always be equal, so the system selects the best phase, based on the preset range, to ensure adequate power supply at all times. The preset switching range, which is entered with the keypad, is saved to the Electronically Erasable Programmable Read Only Memory (EEPROM) of the Arduino Nano microcontroller. When no phase supplies voltage within the preset range, the system switches the load to alternative power supply, if there is any. This system will prevent undesirable voltage supplies and save cost whenever there is need to change the switching range to meet environmental requirement.