GB443910A - Improvements in or relating to electric discharge devices - Google Patents

Abstract

443,910. Systems for supplying discharge apparatus. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and RYDE, J. W., and CATES, J., c /o General Electric Co., Ltd., Wembley, Middlesex. Sept. 7, 1934, Nos. 25797 /34 and 18305/35. Drawings to Specification. [Class 38 (iv)] [See also Group XL] A circuit arrangement for one or more devices of the high-pressure metal vapour kind in which the cold starting voltage and the voltage across the device in its steady running state are much greater than the voltage across the device immediately after starting and in which the hot striking voltage is much greater than the cold striking voltage comprises an alternative path consisting of a discharge device, preferably with a series impedance, connected in parallel across the high-pressure device, and the voltages of the main device and of the alternative path are such that the following conditions are satisfied : (1) the cold starting voltages of the main device and the alternative path must both be less than the supply voltage ; (2) either the cold starting voltage of the alternative path or the voltage across it immediately after starting must be greater than the cold starting voltage of the main device ; (3) the minimum voltage which will cause a current to pass through the alternative path must be greater than the voltage across the main device immediately after starting ; (4) the cold starting voltage of the alternative path must be greater than the voltage across the main device in the steady running state ; (5) the voltage across the alternative path in its steady running state must be greater than the cold striking voltage of the main tube ; preferably also, (6) the impedance of the alternative path when passing current is not very different from that of the main device when passing current. In one example, each main device may be a lamp connected, with a series stabilizing impedance, across the mains. The alternative path may then comprise either an incandescent lamp and a discharge device similar to the main device but without an outer envelope, or with a reduced mercury filling, or another high-pressure lamp with a series choke or condenser. In a modification for street-lighting, a constant-current transformer may supply the series connected primaries of transformers, the secondaries of which supply single lamps; the alternative paths may again consist, of discharge devices and incandescent lamps or of high-pressure lamps and series chokes. The condition (6) must be satisfied in this arrangement. The light-source in the alternative path may be mounted on the same post as the main lamp, or may serve as a pilot light.