GB800532A - Improvements in or relating to electric circuit arrangements for operating low pressure electric discharge lamps and incorporating starting means for the lamps - Google Patents

Abstract

800,532. Starting low-pressure discharge lamps. GENERAL ELECTRIC CO., Ltd. May 4, 1956 [May 4, 1955], No. 13003/55. Class 38 (4). An A.C. low-pressure discharge lamp 1, or a plurality of lamps in series, used particularly for aircraft flashing beacons, has a high-voltage D.C. pulse applied to its starting conductor 4 from an auxiliary supply to ensure striking of the lamp. The starting circuit comprises an inductor 17 in series with relay contact 18 and resistor 19 connected across D.C. terminals 20, 21 in parallel with relay 24 and switch 25. Closing switch 25 energizes relay 24, closing contact 8 then opening contacts 11, 18, the latter inducing a high voltage pulse in inductor 17 which is applied to conductor 4 of lamp 1. The electrodes 2, 3 are fed from transformer secondary windings 12, 13, the primary 9 being connected across the A.C. terminals 5, 6, in series with a resistor 10 to reduce the voltage when running. A capacitor 14 connected between terminal 6 and a tap on the ballast choke 7 improves the power factor; also, the initial charging current causes an increased voltage to be induced across choke 7, thus further aiding the starting conditions. In another embodiment (not shown) a separate capacitor connected across the supply improves the power factor, and capacitor 14 is adjusted to give a smaller starting pulse. An alternative starting circuit (also not shown) utilizes a capacitor discharging into an autotransformer.