GB742487A - Improvements relating to electro-magnetic control devices - Google Patents

Abstract

742,487. Transformers; automatic regulation. HOWE, H. Feb. 20, 1953. No. 4766/53. Classes 38 (2) and 38 (4). [Also in Group XXXIX] A transformer has two main cores each divided into two physically separate subsidiary parts, the subsidiary parts of at least one main core being provided with auxiliary windings separate from the main windings which when excited divert the main flux from the core on which they are wound to the other core. Fig. 1 shows a transformer with two main cores F, G divided into parts F1, F2, G1, G2, having a primary winding P linking both cores and seriesconnected secondary windings S1, S2 on the two cores F, G respectively. Core parts F1, F2 bear respectively two series-connected control windings H1, H2 through which A.C. or D.C. may be passed. The control flux divides between the two parts and voltages in the control windings H1, H2 by the main flux are balanced out. With zero control current the main flux divides between the two cores F, G and the voltages induced in S 1 and S2 are equal and opposed. With maximum control current core F is saturated, no voltage is induced in S1 but only in S2 so that the output voltage is at a maximum. S2 may be omitted if each limb carries control windings H1, H2 and H3, H4, control current being transferred from one set to the other by switches, Fig. 2 (not shown) or a potentiometer K, Fig. 3. The primary winding P and secondary winding S1 may be in autotransformer connection, Fig. 4 (not shown), or each limb may have a separate secondary winding, the output voltage of one decreasing as that of the other increases, Fig. 5 (not shown). The core parts may be square or circular, of laminations or wound strip, each core comprising two concentric pairs placed side by side, Fig. 8, or the four similar parts may be arranged symmetrically, Fig. 7 (not shown). Threephase systems may be controlled by using three separate transformers, one in each phase, the main windings being connected in star or delta, Figs. 11-13 (not shown). Fig. 14 shows an arrangement of a transformer of the kind shown in Fig. 3 in which manual control of the voltage supplied to load R results from alteration of potentiometer K in the supply to control windings H1, H2 and H3, H4 and a control current derived from the load current through rectifier Xa or a current transformer CT and rectifier Xb is fed to an additional control winding H6, so that the output voltage does not vary with the load.