GB705081A - Supply circuit for starting and operating discharge lamps having filamentary electrodes - Google Patents

Abstract

705,081. Supply systems for space discharge apparatus. transformers and inductors. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. June 11, 1951 [June 13, 1950], No. 13784/51. Classes 38 (2) and 38 (4) At least two series-connected discharge lamps 1, 2, Fig. 1, having filamentary electrodes are supplied from an A.C. supply at 5 via a leakage flux transformer 3 the windings of which are arranged in two groups separated by a flux leakage path, one group containing the primary winding 4, the other containing one or two secondary windings 6 supplying the lamp current, and associated one with each group, a pair of series-connected fllament heating second ary windings, 7<SP>1</SP>, 7"; 8' 8<SP>11</SP>; 9<SP>1</SP>, 9" for each end electrode and each intermediate pair of adjacent electrodes ir the series arrangement of lamps. The circuit pro vides maximum discharge initiating and filament heating voltage on applying the supply, but when, after adequate preheating, the lamps strike, the load causes leakage flux to flow between the winding groups to reduce automatically the said voltages to their normal operating values. Instead of the single auto-connected secondary winding 6 shown, it may comprise two sections each connected to each end of the primary winding 4 and each having a tapped portion to provide one of the filament heating windings. The transformer may comprise a shell type core, Fig. 3, upon the central limb 16 of which the two winding groups are disposed one on each side of the leakage flux paths between the central limb 16 and core parts 17, 18.