This standard pertains to ferroresonant voltage regulators that operate at relatively constant frequencies and provide substantially constant output voltages in spite of relatively large changes of input voltage, and to controlled ferroresonant regulators that maintain substantially constant output voltages regardless of variations, within limits, of input voltage, temperature, frequency, and output load. Guides to application and test procedures are included. Provision is made for relating the characteristics of ferroresonant regulators to associated rectifiers and circuits. Definitions pertaining to ferroresonance and ferroresonant regulators that have not been found elsewhere are included with an appropriate discussion. This standard includes, but is not limited to the following types of ferroresonant regulators: (1 ) Series ferroresonant regulators (2) Series-parallel ferroresonant regulators (electrically connected) (3) Ferroresonant transformer regulators (magnetically coupled) (4) Controlled ferroresonant regulators