GB939042A - Improvements in ballast apparatus - Google Patents

Abstract

939,042. Transformers; supply systems for space discharge apparatus. GENERAL ELECTRIC CO. June 2, 1961, No. 19994/61. Classes 38 (2) and 38 (4). A high reactance shell type ballast transformer for discharge lamps has a non-linear magnetic shunt, consisting of one or more laminations disposed between a primary and a secondary winding, and which becomes saturated and de-saturated during each half cycle of the supply. In one embodiment (Fig. 4) having two secondary windings an unsaturated shunt 32, 33 including air gaps 34, 35 is disposed between one secondary 36 and primary 37 while a non-linear shunt 39 is disposed between primary 37 and the other secondary 38. The non-linear shunt 39 may alternatively be formed by lateral projections from the yoke or core leg parts or from both. The core laminations and members are held together by spring clamps 30, 31. The transformer of Fig. 4 may supply two discharge lamps 75, 76 (Fig. 7, not shown) the secondary 36 of high impedance and used mainly for starting taking a lagging current and the secondary 38, associated with the non-linear shunt, taking a leading current. In another embodiment (Fig. 1, not shown) the secondary 36 and shunt 32, 33 are omitted; two such transformers 11 and 11<SP>1</SP> (Fig. 6) having the primary 18<SP>1</SP> of one connected in series with secondaries 19 and 19<SP>1</SP> of both to supply two discharge lamps 57, 58 through a capacitor 74. In a further embodiment (Fig. 5, not shown) two primary windings 41, 42 are disposed on a core one at each end of a secondary winding 43, and a non-linear shunt is disposed between the secondary and each primary. Three spaced apart transverse bridged air gaps 52, 53, 54 are formed in the core leg to prevent saturation of the secondary winding magnetic circuit. The single secondary 43 (Fig. 8) may be arranged in auto-transformer relationship with one of the primaries 42 and supply two discharge lamps 84, 85 in series with a capacitor 89 thereby taking a leading current.