Development of a Microcontroller-Based Online UPS System for Sensitive Electronic Equipment in Hospitals in Gombe State

Hospitals in Gombe State, North East Nigeria, experience frequent power outages that interrupt the operation of sensitive diagnostic and life-support equipment, leading to equipment damage and patient safety risks. This project developed a microcontroller-based online uninterruptible power supply system designed for sensitive hospital electronic equipment loads up to 1 kVA. The design used a double-conversion topology in which AC mains power was rectified, regulated, and inverted continuously, ensuring zero transfer time to battery during outages. An ATmega2560 microcontroller managed the battery charge controller, pure sine wave inverter firing sequence, over-current protection, and a display unit showing input/output voltage, battery state of charge, and load percentage. A 24V 40Ah sealed lead-acid battery bank provided a minimum backup duration of 45 minutes at 800VA load. The inverter output total harmonic distortion was measured at 3.2 percent, meeting the IEC 62040-3 Class 1 specification for sensitive load compatibility. Transfer time was zero milliseconds, confirming true online operation. Efficiency at full load was 87.4 percent. Battery charge time from 20 percent to 90 percent SOC was 4.2 hours at 10A constant current followed by constant voltage charge. The system was bench-tested over 50 simulated outage and restoration cycles with no faults. The study recommends extending battery capacity to 120Ah for a 3-hour runtime target and installing the unit at Federal Teaching Hospital Gombe as a pilot deployment.

Keywords: online UPS, microcontroller, hospital power backup, Gombe State, sine wave inverter