GB190814967A - Improvements in and relating to Electro-magnetically Controlled Switches. - Google Patents

Abstract

14,967. British Thomson-Houston Co., [General Electric Co.]. July 14. Switches.-An electro-magnetic switch, applicable in connexion with systems of motor control in which a number of switches operate automatically in succession to cut out resistance in the motor circuit, and of the kind described in Specification No. 16,195, A.D. 1906, is provided with means, comprising a circuit in inductive relation to the actuating-coil, whereby the operation of the switch is retarded after the energization of the actuating- coil. The switch, which opens its own actuating- circuit after operation, comprises a solenoid 3, magnetic core 4, a contact disk 11 of magnetic material, and contacts 16, 17, also of magnetic material. These contacts 16, 17 are secured by bolts 20, 21 of magnetic material, which are surrounded by solenoids 18, 19 permanently in series with a solenoid 30 in inductive relation to the actuating-solenoid 3. When current in the circuit of the solenoid 3 is building-up to operate the switch, the core 4 is sucked up, but does not move the disk 11, since the latter is held magnetically to the contacts 16, 17 by the flux due to current passing through coils 18, 19, which is supplied by the solenoid 30 and produced inductively by the varying current in the solenoid 3 ; hence the plate 11 is retained on the contacts 16, 17, and the extension 15 of the core 4 rises against the action of a spring 14, which spring causes a rapid break of contact at 16, 17, when the current in the solenoid 3 becomes steady and there is no induced current passing round the coils 18, 19. The contacts may be silver-plated.