GB649627A - Improvements in and relating to magnetic cores - Google Patents

Abstract

649,627. Transformers. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 22, 1948, No. 30321. Convention date, Nov. 25, 1947. [Class 38 (ii)] Relates to a high reactance transformer for use with two fluorescent lamps and comprising laminated core members 1, 2. The section of the leg 1 between yoke-legs 5, 6 carries the transformer primary winding, those portions between legs 4, 5 and 3, 6 mounting separate secondary windings. having leading and lagging currents respectively. In order to obtain substantially equal flux densities in legs 5, 6, the latter has the greater area. Notches 7, 8 are formed in the winding-leg to provide air-gaps, notches 9 being cut out of the member 1 to form gaps which are bridged by shoulders 10. In a modification (Fig. 2, not shown), the notches formed in the left-hand end of the winding-leg are off-set towards the centre of the core so that the shoulders which bridge the gaps make butt contact with the outer portions of the yoke-legs. This tends to prevent fluxleakage, to the metal case of the transformer, for example. The two secondary windings may each carry leading currents, the intermediate yoke-legs being of equal width. Bridged gaps such as 9, 10 are provided on opposite sides of each of the two ends of the core (Fig. 3, not shown). A core, otherwise similar to that of Fig. 3, may be provided with gaps at each end arranged as in Fig. 2 (Fig. 4, not shown).