GB1433402A - Variable reactors and transformers - Google Patents

Abstract

1433402 Transformers and inductors D L HORE 11 July 1974 [11 April 1973] 17412/73 Heading HIT A single or multi-phase variable reactor, autotransformer or transformer comprises a stator with at least one winding thereon and having a constant air gap with a cylindrical laminated iron rotor D which has longitudinal slots carrying a plurality of short-circuit windings, the relative positioning of the axes of the rotor and stator coils determining the reactance of the stator winding or the flux-linkages of one stator winding with another. A three phase variable reactor, Fig. 3c, comprises phase windings A, B and C, each spanning 120 electrical degrees of the stator, and rotor coils X, Y, Z. A single phase variable autotransformer, Fig. 4a, comprises two stator coils AA<SP>1</SP> and BB<SP>1</SP>, with axes at 90 degrees, connected in series across an input voltage and having a variable output voltage tapped across one coil. In the equivalent three phase version (Fig. 4c, not shown) a second set of phase windings (A2, B2, C2) are added to those shown in Fig. 3c as A, B, and C and are displaced 60 degrees therefrom respectively. Secondary windings (S 1 , S 2 , Fig. 5a, not shown) may be laid in the stator slots in proximity to primary windings AA<SP>1</SP>, BB<SP>1</SP>, respectively in Fig. 4a, and the secondary voltages added algebraically to a primary winding voltage to modify the auto-transformer voltage range (Fig. 5c, not shown) or the secondary windings may be connected in series with a load to provide buck/boost regulation (Fig. 5d, not shown). Equivalent three phase constructions are disclosed (Figs. 5e and 5f, not shown). A single phase variable double-wound transformer, Fig. 6a comprises primary windings P 1 , P 2 each spanning 90 degrees of the stator and alternating with secondary windings S 1 , S 2 also spanning 90 degrees, the interlinkages of flux between primary and secondary windings depending on the rotor position (Figs. 6b, 6c, not shown). The secondary windings may be connected in series with a load to form a buck/ boost regulator (Fig. 6d, not shown). In a three phase equivalent the primary and secondary windings of each phase each span 60 degrees of the stator (Figs. 7a, 7b, not shown) and the rotor has three windings (X, Y, Z).