GB191424108A - Improvements in and relating to Controllers for Electric Motors. - Google Patents

Abstract

24,108. Pickerings, Ltd., and Fothergill, J. Dec. 15. Controllers, actuating- mechanism for.-A motor for operating lifts, &c. is reversed by a switch controlled by a single solenoid energized for only one position of the switch, and its main circuit is completed by an independent t electro - magnetic switch which can only be energized when the reversing-switch is at or near the end of its stroke. In the arrangement shown in Fig. 1, the solenoids a, b, c control respectively the starting - rheostat d, the reversing-switch m, n, and the main switch f. When the main switch is open, a tail on the contactarm connects the contacts p, q, thereby placing the resistance r in a braking- circuit across the motor armature s. The contact bar m of the reversing- switch carries an insulated contact i which breaks the " up '' control circuit when the " down " circuit is being used. An auxiliary switch l is opened when the plunger is at the top end of its stroke, and a switch o is opened when the plunger falls to the lower end of its stroke. During the stroke of the plunger, the two switches l, o, are closed and short-circuit the coil c, the various switch contacts being so arranged that the main switch f opens before connexion is broken between the contacts m, n, and g, h. The car switch 3 is moved to the right for upward movement, and current flows from the main 1 through conductor 4, contacts u, v, t, switch 3, conductor 5, contact i, resistance y, and coil c, to main 2. This current closes the main switch f to start the motor with the reversing-switch in the position shown. The switch f also closes the circuit of the solenoid a, and this operates the starter to cut out resistance. For downward movements, the switch 3 is moved to the left. A current then flows from the main 1 through conductor 4, contacts u, v, t, switch 3, conductor 7, solenoid b, and switch l, to the main 2. The reversing-plunger moves to its uppermost position to reverse the armature connexions. The same movement opens switch l, and the circuit from the solenoid b is continued through the switch o and solenoid c, thereby operating the main switch. Economy resistances x, z are used in the actuating-circuits, or the car switch 3 may be connected to the main switch arm by a conductor as shown in dotted line. Instead of the car switch 3, "up," "down," and " stop" buttons may be provided in the car and on each floor-landing, and relays may be arranged to keep the circuit closed after a button has been pressed. In another modification, Fig. 4, the main switch is provided with auxiliary contacts 21, 22 which are bridged by the tail of the arm when the switch is closed. When the "up" button 9 has been pressed and the main switch closed, the solenoid c is supplied through the contacts 22, 21 and "stop" button 11. The auxiliary switch o may be operated by a small solenoid energized during one direction of travel only ; this solenoid may also operate a contact when push-button control is employed, to prevent interference if two persons should press coincidentally "up" and "down" buttons.