Abstract: An emergency supplemental power supply for outage protection of critical electric equipment load powered from a commercial power grid, including a first Variable speed drive, a second Variable speed drive, a first asynchronous motor powered from the first Variable speed drive for turning a fly-wheel attached thereto to ramp-up and maintain a level of expendable kinetic energy in the fly-wheel, the fly-wheel coupled to a first synchronous alternating current generator for driving the generator in a no-load, standby condition, a second asynchronous motor coupled to a second synchronous alternating current generator, in combination, and interposed the second Variable speed drive and the critical electric equipment load, a prime mover including a coupling between the prime mover to the second asynchronous motor/second synchronous alternating current generator combination, and, a computer processor interconnected all elements for maintaining the frequency of alternating current output from the first synchronous al