GB786218A - Improvements in or relating to voltage control devices - Google Patents

Abstract

786,218. Automatic voltage regulation. WAGNER ELECTRIC CORPORATION. May 3, 1955 [May 13, 1954], No. 12779/55. Class 38 (4). [Also in Group XXXIX] The output voltage of a transformer is maintained constant with variations in load or supply by injecting the output of a bridge network, comprising saturable reactors responsive to the said variations, into the input or output circuits of the transformer. The transformer 12 comprises a secondary winding 14 and a primary winding 16, 18 whose induced voltage E is to be kept constant with variations in the supply voltage V1. A compensating winding 20 supplies a bridge network 30 having its output e injected into the primary circuit and comprising opposite pairs of saturable reactors 32, 36 and 34, 38, the reactors in each pair having substantially equal impedance as determined by series-connected D.C. control windings (not shown) for each pair. In operation, the phase and magnitude of the compensating voltage e relative to the supply voltage V1 is determined by the relative impedance of the reactor pairs, the latter in turn depending on the D.C. control currents whose magnitudes are determined by an electrical characteristic of the load or supply. The D.C. control currents may be manually set by potentiometers, Fig. 1 (not shown), and the control windings may be replaced by a manually set core. The opposite pairs of reactors may comprise a single three-legged core having two A.C. windings and a single D.C. control winding. In modifications, Figs. 6-10 (not shown), (1) the bridge is supplied from a second transformer whose primary is connected across the secondary 14 or across the supply voltage V1; (2) the bridge is connected in the secondary circuit of transformer 12 and is supplied from a compensating winding on transformer 12 or from a second transformer whose primary is supplied from the secondary of transformer 12. In the latter case, the bridge may be connected on the load or supply side of the second transformer.