GB803911A - Improvements in or relating to saturable electromagnetic devices - Google Patents

Abstract

803,911. Inductors; automatic regulation. STANDARD TELEPHONES & CABLES, Ltd. May 20, 1955 [May 12, 1954], No. 13880/54. Classes 38 (2) and 38 (4). [Also in Groups XXXVI and XXXIX] A saturable reactor device comprises a magnetic core 1 having a first limb 2 with an energizing coil 3 thereon which coil 3 is fed with direct current to saturate the limb 2 with flux, and a second limb 4 provided with means to ensure that the limb has substantially constant reluctance and having such a cross-sectional area that the limb is not saturated by the flux from the limb 2 whereby a substantially constant magnetomotive force is developed across the limb 4. The incremental reluctance of the saturated limb 2 is high whilst the reluctance of the unsaturated limb 4 is low relatively thereto. The means producing a constant reluctance in the limb 4 may be a gap 5 which may be air or a compressed magnetic dust member may be inserted in the gap. Alternatively one or more such gaps may be provided at any desired situation in the limb, or the limb may be constructed of compressed magnetic dust without a gap. A compensating coil 6 may be placed on the limb 4 to compensate for any variations in the direct current supplying the energizing coil 3. In order to compensate for temperature variations the gap 5 may have associated therewith a magnetic armature carried by a bi-metal element. The core structure is built of laminations and may be either of the form shown in Fig. 4 or Fig. 5. The device shown in Fig. 1 shows an apparatus whereby the current in a load L fed from an alternating current source S may be kept constant. A pair of limbs 7, 8 are provided which are normally saturated by the flux from the limb 2. Coils 9, 10 are placed on these limbs and are oppositely connected in series with the load L. During one half-cycle of the source S one of the limbs becomes de-saturated thereby increasing the impedance of the coil on that limb whilst in the next half-cycle the conditions apply to the other limb. Thus the impedances of the coils 9, 10 are controlled such that the current in the load L is maintained constant. Other applications are described for measuring peak voltages and for magnetic amplification. Specification 650,015, [Group XL (c)], is referred to.