The Whisper-Quiel AC Uninterruptible Power System (UPS) is designed to provide up to 30KW of regulated 3-phase AC power for offices and laboratories where floor space is at a premium and a quiel environment is essential. The system consists of a 36KW rectifier with five minutes of battery backup, which provides uninterruptible power to one or two remote "Whisper-Quiet" Inverters located in nearby offices. The Whisper-Quiet inverter is mounted on the wall of the office and is 26" wide and only 8" deep. The inverter cabinets are rated at 15KW, which is 73"tall, and 20KW unit, which is 89" tall.