GB653437A - Improvements in and relating to electro-magnetic apparatus - Google Patents

Abstract

653,437. Inductances and transformers; electromagnets. LEHMANN, F. Aug. 1, 1947, No. 21109. [A Specification was laid open to inspection under Sect. 91 of the Acts, Aug. 1, 1947.] [Classes 35 and 38 (ii)] Choking coils, transformers, and electromagnets comprise windings of electricallyinsulated ferromagnetic strips carrying both magnetic flux and electric current, which.windings include at least one pair of spiral windings connected electrically at their centres and wound in opposite directions. A transformer may comprise columns as shown in Fig. 2 built of pairs 7 of iron or other ferromagnetic coils wound spirally in opposite directions and connected together at the centre by resilient pins 32. Pairs themselves are connected together by leads 33. Pairs of columns may be magnetically joined at their ends by wound iron yokes, Fig. 17 (not shown). Secondary and other windings formed as pairs of magnetic spirals may be provided or they may be of a conventional character. Where air-gaps are permissible as in choking coils, the pairs of windings 8 are arranged to form a ring, the airgaps being partly or wholly filled with laminated or powdered magnetic material 11, Fig. 3. Where the apparatus comprises superimposed coils, these may be enclosed in a magnetic shell comprising cylindrical pieces 14 with end-plates 15, Fig. 5, or a powdered magnetic material, Fig. 7 (not shown), or the two combined, Fig. 9 (not shown). If in the construction of Fig. 5 end-plates 15 and the winding insulation are both resilient, by moving nuts 17 the distance between the coils can be varied to vary the inductance. The magnetic characteristics of the coils may be improved by making the central turns of thicker, higher permeability iron. Also an additional winding of one to three layers of Cu, Al, Zn or Fe wire in parallel with the coils to carry the magnetizing current may surround the coils. A whole column may be surrounded by such a winding. The iron turns may be insulated by paper wrapped longitudinally with a seam along the outer side of the spirals, or by a layer of oxide or phosphate with or without lacquer. The spirals may be of foils and coated with conducting material.