GB702836A - Improvements in or relating to circuit arrangements for operating electric dischargelamps - Google Patents

Abstract

702,836. Supply systems for space discharge apparatus; series systems. GENERAL ELECTRIC CO., Ltd., and WILLIAMS, C. E. Oct. 18, 1951 [Oct. 18, 1950], No. 25391/50. Class 38 (4) An electric circuit management for operating a plurality of discharge lamps 28 ... 35 at variable levels of brightness include a plurality of transformers 12 ... 19 each having at least one lamp connected to its secondary winding 20' ... 27<SP>1</SP> and whose primary windings 4 ... 11 are serially connected with each other and with a lamp dimming variable impedance 3 to a supply, one or more lamp ballast impedances, and, shunting each transformer primary or secondary winding, a capacitor 44 ... 51 rated to pass in operation a current equal to the transformer magnetizing current when on open-circuit. The ballast may be provided at least partly by the leakage reactance of the transformers, by inductances 36 ... 43 serially connected with each lamp, or by a separate inductance common to all the lamps; in the latter case it may embody the variable impedance 3 and comprise a transductor. The transformers may be auto- -or double-wound. For supplying heating current to the lamp electrodes 70 ... 85 each transformer may have further secondary windings or, preferably, as shown, a separate transformer is provided having secondary windings 54 ... 69 for all the lamp electrodes, and a primary winding 52 which may be connected to the supply through a variable impedance (not shown) linked to the dimming impedance 3 to provide approximately constant electrode heating, such as is disclosed in Specification 657,073.