[en] Doublet III is a magnetic confinement fusion experiment using the Tokamak plasma confinement configuration. Plasma experiments started early in 1978. In the succeeding five years, the demand for additional electrical power has increased as various elements have been added to the original Doublet III device, including neutral beam heating and additional plasma control power supplies. Doublett III is a pulsed device, with a repetition rate of one pulse per five minutes. The ac power is provided by a combination of utility supply systems and from Doublet III energy storage generators. The system incorporates special features to provide a high degree of flexibility and redundancy