Transistor based 400 VA online UPS system

摘要

Online un-interruptable power supply finds wide applications today. On-line UPS systems are used for supplying very critical load such as computers used for controlling important processes and some medical equipments. UPS provides protection against power outages as well as voltage regulation during power line over voltage and under voltage condition. The transistor based 400 VA on-line UPS system consist of battery charger, inverter and various protection circuits. The system designed and fabricated works satisfactorily for the resistive, inductive and computer load. The system gives AC output voltage 230 V at 50 Hz and output power of 400 VA. The system provide 230 V AC, 50Hz and 400 VA output power under mains fail condition. In such case battery supply power to the load and the back-up time is about 35 minutes for 7 AH battery. The switchover time for the system is zero second. The system has full load efficiency of 79.8 %, total harmonic distortion of 7.2 % and voltage regulation of 7.39 %. The system also provide protections such as overload, over voltage, low voltage battery, EMI/RFI and surge protections.