Patent GB-771591-A (GB)
Title: Improvements in or relating to electric lighting fittings for the operation of electric discharge lamps
IPC: H05B41/232
Filed: 1952-06-23
Abstract: 771,591. Supply systems for space discharge apparatus. GENERAL ELECTRIC CO., Ltd., and CATES, J. June 16, 1953 [June 23, 1952], No. 15804/52. Class 38 (4). [Also in Groups XI and XL (a)] A.C. circuits are described for a straight or circular fluorescent discharge lamp which is inserted in a fitting which carries the circuit fittings and is provided with a starting conductor not being a supply conductor for the lamp which is electrically insulated from the rest of the fitting and is supported so as to lie in close proximity to and along the length of the envelope of the lamp. In the circuit shown in Fig. 1 a metal channel or plate 13 forming part of the fitting and from which the starting conductor 11 is insulated is provided and the conductor 11 is connected through a capacitor 12 to the input terminal 3. In operation of the circuit from a single phase supply the input terminals 2, 3 are preferably connected to the supply so that terminal 2 is connected to the phase line and terminal 3 to the neutral line. If the circuit is operated from a 3-phase supply the terminals 2, 3 may be connected to different phase lines. The conductor 11 consists of 14 copper wires 0.0076 inch in diameter coated with polyvinyl chloride. The primary winding 5 of the filament heating transformer 4 is connected across the input terminals 2, 3 with an inductive ballast 6 in series, and the secondary windings 7, 8 are connected in series with the lamp filaments 9, 10. The envelope of the lamp can be coated with a transparent water-repellent coating such as silicone varnish. In the circuit shown in Fig. 2 the primary winding 5 is connected directly across the input terminals 2, 3, the filament heating secondary winding 7 being connected to the input terminal 2 through the ballast impedance 6. In the circuit shown in Fig. 3 the conductor 11 is connected through the capacitor 12 to the end of the secondary winding 8 which is not connected to the primary winding 5, which arrangement reduces the starting voltage. In the circuit shown in Fig. 4 the conductor 11 is connected to the input terminal 3 through a capacitor 12 and an additional secondary winding 14 of the transformer 4, which arrangement also reduces the starting voltage. The conductor 11 consists of two lengths of insulated conductor of the form referred to in connection with Fig. 1. The modifications of the circuit arrangement of Fig. 2 which are shown in Figs. 3 and 4 may also be employed in the circuit of Fig. 1. In a further modification the end of the secondary winding 14, Fig. 4, may be connected to the outer end of the secondary winding 8 at the point 16 resulting in a further reduction in the starting voltage. The inductive ballast 6 shown in Figs. 1, 2, 3 and 4 may be replaced by a capacitor ballast consisting of a choke in series with a capacitor, or by a resistor such as a tungsten lamp. The fitting for the discharge lamp may incorporate an incandescent lamp-holder. The fittings may be adapted for the operation of a plurality of lamps in series, or in parallel, each with its own ballast impedance, the transformer being provided with the appropriate number of secondary windings for supplying heating current to all the lamp filaments, and a common starting conductor may be provided, connected to one input terminal, when the lamps are arranged in line, or parallel conductors, one for each lamp, all connected to the same input terminal, may be provided when the lamps are arranged geometrically parallel to one another.