GB783631A - Improvements in or relating to electric circuit arrangements for starting and operating low pressure electric discharge lamps - Google Patents

Abstract

783,631. Supply systems for space discharge apparatus. GENERAL ELECTRIC CO., Ltd. Feb. 13, 1956 [Feb. 14, 1955], No. 4313/55. Class 38 (4). A D.C. system for starting and operating lowpressure discharge lamps 1 comprises a relay having a winding 2 in series with the lamps and normally-closed contacts 6 between the electrodes of each lamp so as to complete a heating circuit therefor. When energized, the relay opens its contacts and thereby breaks the current through an inductance (which may be provided by the relay winding) connected in series with the lamps so as to generate a voltage pulse for starting the lamps. The relay does not open its contacts until the current passing through its winding exceeds one-third of the maximum current which would flow therethrough if the contacts were held closed with the circuit connected to a supply at the minimum voltage which will give rise to starting of the lamps. In this manner the relay is prevented from operating before the electrodes have been sufficiently heated, or the lamp is prevented from starting with the electrodes cold. A ballast resistor 3 may be replaced by seriesconnected tungsten filament lamps, or, in some cases, the ballast resistance may be afforded solely by the relay winding. In the event of lamp-failure, repeated operation of the relay is prevented by means of a lock-out switch of the bi-metal type.