Abstract: Integrated flywheel uninteruptible power supply (UPS) systems provide reliable back-up power protection in a single integrated housing unit. The integration of the two normally independent systems results in a synergism such that various components may be shared between the systems. For example, the flywheel unit and the UPS electronics unit may utilize a single cooling system that is less complex and requires less energy to operate than two independent cooling systems. Other shared components may include at least control circuitry, user and display interface circuitry, fusing, DC bus capacitors, and emergency shut-off circuitry.