Patent GB-190418202-A (GB)
Title: Improvements in Electric Motor-control and in Apparatus therefor.
Filed: 1904-08-22
Granted: 1905-07-27
Abstract: 18,202. British Thomson-Houston Co., [General Electric Co.]. Aug. 22. Motors, controlling. - Controlling-apparatus for traction motors operated with either alternating or direct current comprises two switches actuated by the same handle to connect up the motors to the different sources, and arrangements for allowing one switch only to be closed at the same time ; the switch for varying the field cannot be moved except when both of the other switches are in the ' off ' position. The switches are for use in a motorcontrol system such as is described in Specifications Nos. 18,201 and 18,203, A.D. 1904, and shown in Fig. 1, in which C is a series-parallel controller, R a switch for reversing the direction of motion of the motors, E a switch for connecting the divided fields of the motors in series and parallel for the direct and alternating sources, A, D the two main switches for the two sources, and m an auxiliary motor for driving an air-compressor. The vessel of the switch D, shown in section in Fig. 2, contains oil in which are suspended the stationary contacts 2, 2 with which engage movable contacts 3 carried by a rod 4, movable in a vertical direction through an insulated bushing 6. The rod 4 is connected to the vertically-movable rod 8, the lower end of which is attached to one arm of a bell-crank lever 9 the other arm of which carries a pin 10 engaging a slot in the pivoted lever 11, which is attacbed to the member 12 on the shaft 13. Near its other end the shaft is formed square &c., to engage with the operating-handle 14, which rotates both the shaft and the member 12, so moving the pivoted links 11, 15, the link 15 engaging a pin 17 on the bell-crank lever 16, the other arm of which engages the operating-rod 18 of the switch A. If the handle be moved to the central position, the member 12 rotates, and the link 11 moves towards the right and allows the bell crank 9 to be rocked by the spring 19, thus raising the rod 8 and opening the switch D. If the motion of the handle 14 is continued to its other extreme position, the crank 9 will be left in position against the stop, the link 15 will rotate the crank 16 to close the switch A, while the member 12 and the links 11, 15 act as toggle-joints to give a strong closing pressure and to lock the switch in position against the spring tension. The spring restores each switch to its open position when the handle is moved to its ' off' position, and, if the spring 19 breaks, the two switches are still prevented from closing at the same time by the member 22 carried by the handle 14 and the two pins 23, 24 carried on extensions of the bell cranks 9, 16. When the handle is moved to the opposite position to that shown, the member 22 engages the post 23 and rocks the lever 9 to open the switch D before the switch A is operated. A stop 20, which presses against springs 21<a> carried by the flange 21, is provided on the arm 14. The flange prevents the withdrawal of the handle 14 from the shaft 13 in any but the ' off' position, in which position the flange is cut away. Fig. 3 shows the top of the commutating- switch E, the shaft of which can be operated only by the handle 14 of the switches D, A, so that the main supply must be cut off before the commutator switch can be changed. Flanges 25, 26 on the switch E allow the insertion and withdrawal of the handle only at the two ' off ' positions.