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US 4,860,145 AGranted
Tap switching protection circuit
AssigneeOneac Corporation
InventorAugust G. Klingbiel
Life of this patent
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AssigneeOneac Corporation
InventorAugust G. Klingbiel
Estimating the term…
A protection circuit is provided for a tap switching line voltage regulator of the type which selectively switches in one of a predetermined number of taps on a winding of a transformer. The selective switching of the taps is controlled in response to the sensed load voltage to provide a regulated voltage to a load in the presence of a varying input line voltage. The tap switching line voltage regulator in response to the sensed load voltage controls the conductive state of a solid state series switching element in each of the switched tap lines. The protection circuit provides current limiting inductors in series with each of the solid state switching elements with all the inductors being wound on a common magnetic core. When switching from one tap to another tap, the tap switching line volage regulator in response to the sensed voltage operates to select an adjacent tap to the tap currently selected. Thus, tap switching proceeds in a sequential fashion up and down along the taps. The series inductors are wound on the common magnetic core such that the direction of the windings alternates between adjacent taps. Accordingly, the protection circuit provides a current limiting impedance to circulating currents that is four times the impedance to normal load currents. Accordingly, the circulating current caused by leading or lagging power factor operation is limited to prevent damage to the solid state switching elements.
In a circuit for switching a common point from one AC power line to another AC power line of a plurality of at least three AC power lines that are of the same phase but at differing voltage potentials, solid state switching device means being coupled in series with each of said AC power lines and said common point, each of said solid state switching device means including a control connection responsive to a control signal for selectively actuating said solid state switching device means to provide a single conduction path, and a current limiting inductor connected in series with each of said solid state switching means and connected in series with a respective one of each of said AC power lines, said inductors being wound on a common core and in a common winding sense to a circulating current between each adjacent pair of said AC power lines.
A protection circuit for a tap switching line voltage regulator that includes a plurality of at least three tap lines of the same phase but at differing AC voltage potentials, a solid state switching device connected in series with each of said tap lines having a single conduction path controlled via a control input, and a common supply point commonly connecting one side of each of said conduction paths of said solid state switching devices, said protection circuit comprising a plurality of current limiting inductors, one of said inductors being connected in series with each of said solid state switching devices and connected in series with each of said tap lines, said inductors being wound on a common core and connected in circuit such that the winding sense is opposite for said inductors corresponding to said tap lines that are immediately adjacent in terms of AC voltage potentials.
Tap switching line voltage regulator apparatus comprising;
Dependencies are inferred from the claim text.