GB737048A - Improvements in and relating to arc discharge tube ballast transformers and circuits therefor - Google Patents

Abstract

737,048. Electric transformers; supply systems for space discharge apparatus. GENERAL ELECTRIC CO. July 20, 1953 [July 25, 1952], No. 20058/53. Classes 38 (2) and 38 (4). A high reactance ballast transformer 5 for a plurality of serially-connected arc discharge tubes, e.g. fluorescent lamps 2, 3 each having two heatable cathodes 28, 33; 30, 34, one at each end, comprises a central winding leg 8 and a yoke consisting of two separate members 9 positioned on opposite sides of the leg 8, the leg and yoke embodying a bridged gap 10, 11 and the yoke members having leg portions intermediate the ends to form shunts having gaps between the leg portions and the central leg 8 ; the windings on the leg 8 comprise a step-up auto connected secondary winding 13 disposed between the bridged gap end of the yoke and the intermediate leg portions, a primary winding 12 between the latter portions and the other end of the yoke, and cathode heater supply windings 15, 16, closely magnetically coupled with the primary winding, for supplying the parallel interconnected adjacent cathode 33, 34 of electrically adjacent lamps and the cathode 30 at one end of the series group, the heater supply for the cathode 28 at the other end of the group being provided by extended turns of the primary winding beyond its input terminal 14. The core may be of the type disclosed in Specification 717,286. A capacitor 7 in series with the secondary winding causes the lamp operating current to lead, and any one of the lamps may be shunted by a starting capacitor 6.