GB648857A - Improvements in circuit arrangements for operating gas- or vapour-filled electric discharge devices - Google Patents

Abstract

648,857. Supply systems for space discharge lamps. GENERAL ELECTRIC CO., Ltd., and WILLOUGHBY, A. H. Nov. 26, 1947, No. 31313. [Class 38 (iv)] To ensure immediate restarting of a discharge device, particularly a high-pressure metal vapour lamp D, when an interrupted main supply source is restored a subsidiary supply circuit is connected to the lamp, when relay C1 becomes de-energized, in order to provide a small current and maintain an appreciable ionization within the device without preventing the device to cool down, the subsidiary supply circuit being automatically disconnected when the relay is energized upon restoration of the normal supply. The subsidiary supply source may comprise a battery B arranged to be disconnected or discharged at the end of a period sufficient for the temperature of the device to be low enough to permit restarting by the normal supply voltage and the battery may be recharged upon restoration of the normal supply. Contact 2 is arranged to close before contact 1 opens to avoid interruption of the lamp current, and an inductance L included in the subsidiary supply circuit provides a voltage pulse to the lamp during change-over to maintain ionization during the switching operation, this pulse finding its way to terminal T2 through the stray capacitance of relay contacts 3, 4 or a condenser (not shown) connected between terminal T2 and the junction of choke L and resistor R3. A switch 53 may be coupled with switches S1, S2 for rendering the subsidiary supply circuit inoperative controlling the normal supply to the lamp.