GB767987A - Improvements relating to supply circuits for electric discharge lamps - Google Patents

Abstract

767,987. Supply circuits for space discharge apparatus. CROMPTON PARKINSON, Ltd. June 23, 1955 [July 7, 1954], No. 19911/54. Class 38 (4). In a supply circuit for at least two electric discharge lamps 1, 15 each having two electrodes 2, 3 and 17, 18 requiring preheating before starting of the lamps, said lamps being connected in parallel with one another to a source of supply 9 each in series with a respective ballast 8 and 16, 23, one, 1, of the lamps has connected in parallel with it the primary winding 7 of a starting transformer 6 of which one secondary winding 4 is connected to heat only one electrode 2 of said lamp 1 whose other electrode 3 is heated before starting only by the discharge current of the other lamp 15 which latter has both its electrodes 17, 18 heated by further secondary windings 19, 20 of the transformer 6. Where three or more lamps are used the first of the group has both electrodes heated by the transformer, the last of the group is shunted by the transformer primary winding, while each lamp after the first has one electrode heated by the transformer and the other by the discharge current of the preceding lamp of the group. By these circuits parallel connected lamps may be started by a transformer in parallel with one of them without the risk of not all the lamps starting due to the transformer voltage falling when the lamp across which it is connected starts.