Uninterruptible Power Supply System operates on a rating of 500VA-10KVA. The Power Supply System prevents damage of computers due to sustained low voltage, spikes, surges, brown outs and failure. The Power Supply System is based on Mosfet/ IGBT switching device that is High frequency switching at 20khz pwm. The Uninterruptible Power Supply System is equipped with Soft start Thyristor controlled rectifier.