True on-line double conversion micro-controller based UPS system for high end servers, workstations, CADCAM...sensitive to AC power irregularities and blackout. The high switching frequency of the UPS enables fast response to dynamic loads like CNCs, textile and printing equipment, glass processing, medical equipments..., resulting in good transient response for non-linear loads. The UPS is designed to support advanced electronic equipments with high crest factor demand and provides unmatched performance.