Design and Implementation of an Arduino Based Undervoltage Relay

All human activity is highly dependent on the stable availability of electrical energy. Electrical distribution disruptions, such as over/under voltage spikes or drops, can disrupt daily activities. To anticipate this, an Arduino-based over/under voltage control system was designed that utilizes the PZEM-004T sensor to monitor AC voltage in real-time from a power source or variable transformer. The system uses an on-off control method on the relay with three operating conditions: under voltage (voltage 157.5V). SMPS (Switched-Mode Power Supply) is integrated as a stable power supply for Arduino Uno microcontrollers and other electronic components, ensuring that system performance remains optimal despite input voltage fluctuations. The sensor reading results and voltage condition status can be displayed locally via a simple interface such as an LCD or LED indicator, without relying on internet communication. By combining the reliability of Arduino Uno and SMPS efficiency, the system is able to protect electrical devices from damage due to voltage instability while ensuring energy-efficient operation.