GB412235A - Improvements in and relating to electrical systems for providing a sequence of operations - Google Patents

Abstract

412,235. Electric supply systems. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Suits, C. G. ; 1740, Union Street, Schenectady, New York, U.S.A.) Dec. 22, 1932, No. 36353. Convention date, Dec. 23, 1931. [Class 38 (iv).] In an electrical system for operating a number of load devices, e.g. lamps, in succession, each of a number of branch circuits includes a load device and a grid-controllable electric discharge device in series therewith, and means entirely electrical (i.e. without mechanical moving parts) are arranged to act in response to operation of one of the discharge devices and energization of the corresponding load device, to ensure the delayed supply of a voltage to the grid of the discharge device in another branch circuit and hence the delayed energization of the load device in that circuit. Fig. 1 shows such a system in which the delay is due to the time lag in a saturable core reactor. The lamps 4 .. 7, each in series with an electric discharge device in a separate branch circuit connected across the alternating current supply 1, 2, are each shunted by the saturating winding 18 of a saturable core reactor 17 of which the alternating current winding 16, in a branch circuit, is provided with series and shunt resistances 13, 15 respectively and connected as shown through a resistance 12 with the grid 11 of the vapour discharge device in another branch circuit. The grid 11 of the device 10 in circuit with the lamp 4 is similarly connected through a resistance 12 to a branch circuit including a resistance 13 and a switch 14. With the switch 14 open, no lamp is illuminated. On closing the switch, the device 10 in circuit with the lamp 4 becomes conducting, the lamp 4 is illuminated, and saturating current, supplied to the winding 18 of the associated reactor 17, decreases the inductance of its winding 16 sufficiently to supply a voltage to the grid 11 of the device 10 in circuit with the lamp 5, causing the delayed illumination of that lamp and thereafter of the successive lamps of the series. Similarly, on opening the switch 14 the lamps are successively extinguished. The saturable reactors used may be of the type described in Specification 103,842, [Class 38 (iv)], or may each comprise a pair of transformers with direct current windings in series and alternating current windings in parallel and reverse to prevent induction of current in the direct current windings. Fig. 2 shows another system in which the delay is due to the time required to charge or discharge a condenser. The lamps 4, 5, 6 are each shunted by a condenser 32 and a resistance 33 and the positive plate of the condenser is connected through a resistance 12 to the grid 11 of the discharge device 10 in the next branch circuit. The grid 11 of the device 10 in circuit with the lamp 4 is connected through a resistance 12 with a switch 14. With the switch 14 open, no lamp is illuminated. On closing the switch the device 10 in circuit with the lamp 4 becomes conducting, the lamp 4 is illuminated, the associated condenser 32 is slowly charged until it supplies a voltage to the grid 11 of the device 10 in circuit with the lamp 5 sufficient to make the device conducting, thus causing the illumination of the lamp 5 and thereafter the delayed illumination of the successive lamps of the series. Similarly, on opening the switch 14, the lamps are successively extinguished. The invention is applicable to electric signs or to beacon or field border lamps at an airport, or for controlling the speed of traffic, e.g. in tunnels, by causing light impulses to travel at the speed desired for the traffic. The Specification as open to inspection under Sect. 91 comprises also the use of the invention " to mark the runways in airports in accordance with the wind direction " and for " railroad crossing protection." This subject-matter does not appear in the Specification as accepted.