Patent GB-190605003-A (GB)
Title: Improvements in Controlling Devices for Electric Motors, applicable to the Motors of Elevators or Lifts and the like.
Filed: 1906-03-01
Granted: 1906-05-24
Abstract: 5003. Otis Elevator Co., [Otis Elevator Co.]. March 1. Lifts.-Relates to controlling- devices for alternating-current motors in a push-button liftcontrolling system, in which the motor is operated by polyphase current and the controlling- devices by single-phase current taken from two of the mains. By closing one of the pushbuttons, either at the landings or on the car, a circuit is completed through one of the relays 11, 22, 33 to close one of the motor-starting switches 20, 30, at the same time switches being automatically operated to prevent any interference from other possible circuits. As soon as the motor circuit is completed, the brake 50 is released and as the motor 40 speeds up resistance 60 in the rotor circuit is gradually and automatically cut out, the circuit through the relays 11, 22, 33 being broken when the lift reaches the landing desired, and the motor 40 brought to rest by the application of the brake 50. By closing for instance the landing pushbutton 3, the circuit of the floor relay 33 is completed from the main a through lead 67, fuse 98, magnet 33, button 3, inductive resistance 80, contacts 78, 81 which are bridged by a contact 79 normally held in engagement with the contacts 78, 81 by a weight on the lever connecting the cores 94, 93, contacts 25, 26, 36, 35, safety button 9, gate contact 8, door contacts 3<1>, 2<1>,1<1>, and slack-cable switch 4 to the main b. The core of the energized floor relay 33 rises, bringing the brush 76 into engagement with the contact-strip 87 of the floor controller, and thus completing the circuit of the coil 27 of the motor switch 20 through the coil 33, contact-strip 87, contact-ring 88, leads 89, 83, &c., the relay 33 being thus maintained energized when the push-button 3, which is only momentarily closed, is opened. The energized coil 27 raises the core 28, bringing the contacts 23, 24 into engagement with the contacts 21, 22 and so completing the circuit of the motor 40 and also the circuit of the electro-magnetic release brake 50, at the same time separating the contacts 25, 26 and so breaking the circuit containing the landing push-buttons 3, 2, 1. The current in the coils 51, 62 of the electro-magnetic device for cutting out the resistance 60 in the rotor circuit depends upon the voltage of the mains, and the current in the opposing coils 54, 63 upon the voltage induced in the rotor, so that at starting the switches 70, 75 remain open until the induced voltage has sufficiently decreased to allow the coils 51, 62 to raise their cores, the successive operation of the switches 70, 75 being brought about by having the resistance 55 larger than the resistance 61. As the lift reaches the desired landing, the brush 76 of the floor controller leaves the segment 87, thereby breaking the circuit of the coils 33, 27 and thus opening the motor circuit and allowing the brake 50 to be applied. If, instead of operating the landing push-button 3, the push-button 14 on the car is closed, the circuit of the relay 33 is completed through the coil of the electro-magnet 90 instead of through the coil 80, the inductive resistances of the two coils being equal. The core 93 of the electro-magnet 90 is raised, opening the switch 79 and closing the switch 95, which completes the circuit of the coil 85 across the mains a, b through the switches 9, 8. The switch 79 is thus maintained open until the lift gate is opened, so that no interference can result from the operation of the landing switches 1, 2, 3 while the lift is moving. Should the car overrun its travel, the limit switches 66, 65 operate to open the circuit of the switches 20, 30. The car can be stopped at any point in its travel by operating the switch 9 which normally closes the circuit operating the switches 20, 30.