Design, Construction and Testing of an Uninterruptible Power Supply of 300 Watts Capacity

The interruption of power supply is a source of concern to the consumer, and gives rise to the need to provide emergency power source in some important areas of both domestic and industrial application. This has led to the design and construction of the Uninterruptible Power Supply (UPS). In this work, we made use of solid state components, with the aid of background knowledge in the field of electronics, to locally manufacture a UPS which could be used for back-up power for critical and essential loads. For the design, a battery is used to provide direct voltage and current, which is inverted by the inverter. The inverted 12v a.c., 50 Hz, is transformed using the transformer to 240v a.c., 50Hz. The system also has in-built voltage reversal protection, automatic change-over and battery charger, which recharges the battery for continuous use when mains supply is restored. The output power of the constructed device was found to be 290 watts (determined by power transistor), which gives a percentage error of 3.3%