GB608108A - Improvements relating to voltage regulating apparatus for alternating current circuits - Google Patents

Abstract

608,108. Automatic voltage regulation. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and WALKER, A. H. B. Feb. 15, 1946, No. 4805. [Class 38 (iv)] In voltage regulating apparatus of the kind comprising two magnetic circuits and provided with an input winding or windings connected to an A.C. supply, and secondary windings connected in series opposition with one another and in parallel with a series connected condenser and inductance across the load circuit, one of the magnetic circuits being operated at a relatively high flux density above the knee of the B-H curve, the effective permeability of this latter magnetic circuit is arranged to be varied in order to vary correspondingly the basic magnetic condition or characteristic at which regulation is effected. The basic magnetic flux may be derived from a permanent magnet associated with the circuit. The invention is applicable either to single phase systems or to the polyphase system described in Specification 584,420. Fig. 2 shows an arrangement wherein one transformer T2 has auto-connected primary and secondary windings divided into two parallel connected portions carried on the outer limbs of a three-limbed core, the primary windings being in series with those of transformer T1 across the supply terminals 1, 2. The winding arrangement is such that no alternating flux due to the alternating current in these windings traverses the centre limb of the core. The centre limb carries an auxiliary winding 5 which is energized with D.C. current supplied through a rectifier unit V fed through a small transformer T3 connected across the A.C. supply 1, 2, an adjustable resistance R being provided to vary the current through the winding 5. Alternatively, the rectifier unit V may be fed from an auxiliary winding on the outer limbs of the transformer T2. In a modification, Fig. 3 (not shown), the rectifier unit V is arranged to inject a direct current into the primary and/or secondary windings on the outer limbs of transformer T2. A further modification, Fig. 4 (not shown), has the autotransformer primary and secondary windings on the centre limb of transformer T2, and an auxiliary winding 5 in two series connected parts on the outer limbs energized with D.C. from a rectifier unit. The ripple voltage developed in the auxiliary winding is rectified and increases the saturation of the core, thereby increasing the sensitivity of the control exercised by the direct current fed to the auxiliary winding. Specifications 548,526 and 597,371 also are referred to.