GB715610A - Improvements in or relating to variable inductive elements having saturable cores - Google Patents

Abstract

715,610. Magnetic amplifiers. GENERAL ELECTRIC CO., Ltd., and WILLIAMS, C. E. Sept. 20, 1951 [Sept. 20, 1950], No. 23093/50. Class 40 (4) [Also in Group XXXV] To increase the range of inductance variation in the main controlled A.C. winding obtainable with a given range of direct current through the controlling saturating D.C. winding of a transductor such as for discharge lamp dimming circuits, which transductor has a threelegged magnetic core of stacked laminations upon which the windings are so arranged that there is substantially eliminated from the centre leg either the D.C. flux or A.C. flux of fundamental frequency, an additional but separate body of magnetic material is provided for'that part of the core which carries all the D.C. flux but none or only part of the A.C. flux thereby increasing the cross-sectional area of such part. As shown, the additional body 9 of stacked laminations is provided on the centre leg 2 which carries the saturating winding DC, while the outer legs 1, 3 of the core 4 carry the main winding which is split into two serially connected parts AC1, AC2 so directed that their magnetic flux flows through the core yokes 5, 6 but not through the centre leg 2. The body 9 alternatively may be so disposed as to increase the leg width, or both the width and the stack thickness. In other winding arrangements, the A.C. winding may be in two parallel connected parts or the D.C. winding may be in two series connected parts also disposed on the outer legs but so directed that the flux of each part flows through the centre leg. Alternatively the arrangement and direction of the two windings may be the opposite of that shown, in which case the body 9 is added only to one outer leg. Variation of the number of laminations in the body 9 may provide means for adjusting the characteristic of the transductor.