A line voltage regulator having magnetic-amplifier control

Closely regulated supply voltages decrease maintenance, improve reliability, and simplify the design of electron tube and semiconductor circuits. There has existed a need for an alternating-voltage regulator which is effective for simultaneous variations in line voltage, load, and frequency, and which has a degree of reliability beyond that associated with electron-tube regulating circuits. Such a regulator, having a 3-kilovolt-ampere (kva) 115-volt 60-cycle rating is described. A power circuit consisting of a saturable reactor and a buck-boost transformer are controlled in a feedback loop by means of a cascaded 2-stage magnetic amplifier. Reference current is provided by a thermistor network and a silicon-carbide varistor is employed as a current preamplifier. These elements are insensitive to frequency over a ±5-per-cent range. The field of application for this type of regulator includes loads within the range of 1 to 20 kva where extremely fast regulation is not essential.