GB735226A - Improvements in or relating to electric circuit arrangements for operating electric discharge lamps - Google Patents

Abstract

735,226. Supply systems for space discharge apparatus; automatic regulation; electric transformers. GENERAL ELECTRIC CO., Ltd., and CATES, J. Feb. 13, 1953 [Feb. 1, 1952], No. 2773/52. Classes 38 (2) and 38 (4). To reduce filament heating current variations due to supply voltage fluctuations and. to filament resistance variations, each filament heating secondary winding S1, S2 in an electric circuit arrangement for a heatable electrode discharge lamp L is divided into two seriesconnected voltage aiding portions of which one S11, S21 is wound on the same part of the core M as the primary winding P so as to be closely magnetically coupled thereto, while the other S12, S22 is wound on a different part of the core, whereby a magnetic leakage path or paths N1, N2 is introduced into its coupling with the primary winding; this arrangement is applicable only to circuits wherein for supplying the lamp discharge current there is either no secondary winding, or if one is provided it is closely magnetically coupled with the primary winding. The windings may be arranged on a core-type core in the manner shown in Fig. 2, or on a shell-type core with the high reactance secondary portions either on respective outer limbs or on the outer parts of the centre limb, the primary winding and closely coupled secondary portions being on the centre limb, in the centre thereof and separated by ferromagnetic shunts from the high reactance secondary portions in the latter case. The lamp may be a low-pressure mercury vapour fluorescent lamp and may have an earthed starting stripe E. A ballast choke B and a radio interference suppression capacitor C are provided. Specification 658,113 is referred to.