GB735304A - Improvements in or relating to saturable reactors - Google Patents

Abstract

735,304. Inductors. WILLHEIM, R. May 12, 1953 [May 13, 1952], No. 12090/52. Class 38 (2). [Also in Group XXXIX] A saturable reactor or magnetic amplifier comprising a core 501 having three limbs 502, 503, 504 carrying two A.C. windings 505, 506 on the outer limbs 502, 503 respectively, these two windings and a load device 519 being connected in series and supplied with alternating current and a controlling D.C. winding 507 carried by the centre limb 504 and fed with a controlling direct current, is characterized by the provision of three auxiliary windings 511, 512, 513 which are connected in delta and serve to suppress or substantially decrease the leakage fluxes which extend from yoke to yoke of the reactor in paths other than those formed by the core limbs. Thus, any unbalance of the fluxes in the limbs 502, 503, 504 will cause a current to circulate in the delta connected auxiliary windings 511, 512, 513 which tends to restore the flux balance in the limbs so that the leakage fluxes are eliminated. The delta connected auxiliary windings may have a low impedance such as a resistor 514 or a capacitor 515 included in circuit thereby reducing the retarding effect on the operation of the reactor of transient changes in the D.C. flux. D.C. may be injected into the delta connected windings across the winding on the centre limbs, thus these windings may also serve as D.C. biasing windings. A feed-back winding 516 may be provided, fed with direct current over a potentiometer 518 from a rectifier bridge 517 included in the series connection between the A.C. windings 505, 506. In other embodiments certain of the windings on the outer links may carry 100 per cent feed-back current whilst a winding on the centre limb carries a feed-back current suitably modifying this value. In a further modification the A.C. windings and the feed-back windings are combined and placed in series with half-wave rectifiers thereby producing a so-called " selfsaturated" reactor. Biasing windings fed with D.C. may also be provided. Two or more saturable reactors may be used in a cascade arrangement, which reactors may, or may not, be of similar construction.