Patent GB-412219-A (GB)
Title: Improved arrangements for controlling electrical devices in a predetermined sequence
IPC: G05B19/07
Filed: 1932-12-21
Abstract: 412,219. 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. 21, 1932, No. 36240. Convention date, Dec. 23, 1931. [Class 38 (iv).] In an electrical system for operating a number of load devices, e.g. lamps, in sequence from an alternating current supply, each of a number of branch circuits includes one or more of the load devices and each branch circuit is provided with control means entirely electrical (i.e. operating without mechanical movements), comprising a saturable core reactor of which the core saturation is dependent on the energization of a load device in another branch circuit, such energization causing a delayed operation of a load device in the former branch circuit by producing a delayed change in the impedance thereof, each reactor being provided with a load winding connected with a load device in the said former branch circuit and a control winding connected across a load device in the said other branch circuit. Fig. 1 shows such system in which each branch circuit connected across the alternating current supply 1, 2 includes a lamp 4 .. 10 and the alternating current winding 12 of a corresponding saturable core reactor 13 of which the direct current saturating winding 14 is connected through a full-wave rectifier 15 across the lamp of the preceding branch, or, in the case of the first branch circuit, through a similar rectifier 16 across the winding 12 in one of the other branch circuits, e.g. as shown, that containing the lamp 8. With the switch 17 in the first branch circuit open, the lamp 4 is out of circuit and the inductance of each winding 12 in the other branch circuits is too high to allow sufficient current to illuminate the corresponding lamps 5 .. 10. The rectifier 16, however, supplies sufficient current to the reactor 13 of the first branch circuit to decrease the inductance of its winding 12 so that on closing the switch 17 the lamp 4 is illuminated and the associated rectifier 15 supplies sufficient current to the reactor 13 associated with the lamp 5 to decrease the inductance of its winding 12 and thus to illuminate that lamp and so on to illuminate the lamps 6 .. 10 in succession, the delay being due in part to the time lag of the reactors and in part to the relatively slow energization of the lamps. The decrease of the inductance of the winding 12 associated with the lamp 8 thereupon causes the rectifier 16 to supply so little current to the reactor 13 of the first branch circuit that the inductance of its winding 12 increases and the lamp 4 is extinguished and the lamps 5 .. 10 are thereafter extinguished in succession. The extinguishing of the lamp 8 is, however, associated with an increase in the inductance of its associated winding 12 resulting in reillumination of the lamp 4 and thereafter of the successive lamps as before. Such a system of automatic periodic successive illumination and successive extinguishing of a series of lamps is applicable to electric signs, airport beacons and field border lights and for controlling the speed of traffic, e.g. in tunnels, by causing a wave of illumination to travel at the speed considered desirable for the traffic. If the reactor 13 in the first branch circuit is omitted, each closure of the switch 17 causes the lamps to be illuminated in succession and to remain illuminated until the switch is opened; the number of lamps illuminated thus depends on the duration of the closure and the arrangement is therefore available for signalling, e.g. to aircraft from the ground, by Morse code or otherwise. Fig. 2 shows a modified system in which branch circuits 35, 36, 37 each include a pair of lamps 38 and 39, 43 and 44, and 47 and 48 respectively, the lamps 38, 43 and 47 being of higher rating than the lamps 39, 44 and 48 respectively. The lamps 39, 44 and 48 are connected across the alternating current windings of reactors 40, 45 and 49 of which the saturating windings are arranged to receive direct current through rectifiers 41, 46 and 46<a> respectively. Rectifiers 46 and 46<a> are connected as shown across the lamps 39 and 44 respectively and rectifier 41 is connected across the supply circuit through a switch 42. With the switch 42 open, lamps 39, 43 and 48 only are illuminated. On closing the switch, lamps 38, 44 and 47 are successively illuminated with simultaneous extinguishing of the lamps 39, 43 and 48 respectively, whereas on opening the switch the lamps 39, 43 and 48 are successively illuminated with simultaneous extinguishing of the lamps 38, 44 and 47 respectively. In another system, Fig. 3, the frequency of the successive illumination of a series of lamps 4 .. 7 .. is determined automatically by control from a non-linear pulsating circuit 50 including the lamp 4, a condenser 51 and the alternating current winding 52 of a saturable core reactor 53 of which the saturating winding 54 is energized from the supply circuit 1, 2 through a rectifier 55. The saturable core reactors used throughout may be of the type described in Specification 103,842, [Class 38 (iv)], or may each comprise a pair of transformers with the saturating windings in series and the alternating current windings in series and the alternating current windings in parallel and reversed to prevent induction in the direct current circuit. The Specification as open to inspection under Sect. 91 comprises also references to the application of the invention " to mark the runways in airports in accordance with the wind direction " and in " railroad crossing protection." This subject-matter does not appear in the Specification as accepted.