Modular 3-phase intelligent, true on-line UPS system provides 100% system availability with N+1 modular architecture and 1+1 parallel capability. In N+1 configuration, it provides two self-contained, redundant 20kVA power modules that can be hot-swapped (load remaining powered) if maintenance is required. In 1+1 configuration, two SU40KX models connected in parallel can provide fail-safe redundancy (two 40kVA models supporting 40kVA load) or increased capacity (two 40kVA models supporting 80kVA load). Large capacity 40,000VA/32,000W UPS continually converts incoming AC power into filtered DC power, and then resynthesizes it back into AC power with pure sine wave. Perfectly regulated, continuous sine wave output with zero transfer time assures compatibility with all equipment types. High input power factor, advanced IGBT inverter technology and digital signal processor (DSP) technology produce less than 3% input total harmonic distortion (THDi). With low THDi, generators run cooler and last longer, allowing managers to save installation costs by installing a generator with a capacity equal to the equipment load (1:1 ratio).