GB704917A - Improvements in and relating to laminated magnetic cores - Google Patents

Abstract

704,917. Transformers and inductors; supply systems for space discharge apparatus. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 4, 1951 [Dec. 6, 1950], No. 28424/51. Classes 38 (2) and 38 (4) A laminated magnetic core (Fig. 2) for the respective windings 7, 8 of a combined autotransformer and ballast reactor for a fluorescent lighting system (Fig. 3) comprises a number of layers each having two E-shaped laminations 1, 2 the legs of which abut corresponding legs of a double E-shaped lamination 3, whereby to provide two shell-type flux paths, air gaps 4, 5 being provided in each central winding leg by shortening, relative to the centre legs, the centre legs 3a, 3b of lamination 3, and possibly also the centre legs 1a, 2a of laminations 1, 2. The system comprises the series circuit of two fluorescent discharge lamps 9, 10, an overall capacitative ballast therefor comprising the reactor winding 8 and a capacitator 12, and a portion 7b of the autotransformer winding 7, and is connected through a switch 15 to an A.C. supply. On starting, energization of portion 7a of winding 7 causes portion 7b to add its voltage to the supply voltage to strike lamp 10, whereupon capacitor 11 becomes the major impedance of the circuit and strikes lamp 9. Removal of either lamp de-energizes the transformer winding.