Survey of rotary uninterruptible power supplies

Uninterruptible power supplies (UPS) for early warning radar systems, computer centers, and other critical loads, were first introduced as motor generator sets with flywheels and engines. Since that time, solid state UPS have been developed to a high degree in a wide range of sizes and have largely supplanted rotary uninterruptible power systems. There has been a renewed interest in rotary UPS as an alternative to static UPS. The features of sample rotary and hybrid rotary UPS are described.