Barber-Nichols designed and built a 6 kW Uninterruptible Power System that utilized a High Inertia Turbine (HIT 6).
The alternator is situated between the turbine wheel and the 2.0 kg (4.5 lb) fly wheel. When the unit is on standby the alternator acts as an electrical motor, consumes a small amount of power, and maintains the unit’s rotational speed at 60,000 rpm.
In the event of a power failure, the alternator, now driven by the fly wheel’s inertia, immediately begins generating electrical power. After two seconds, propane flowing to the turbine takes over and the alternator continues generating electricity for as long as is necessary.
