Patent GB-100872-A (GB)
Title: Improvements in Electric Motor Control Systems.
IPC: H02P7/298
Filed: 1916-02-03
Abstract: 100,872. Igranic Electric Co., (Cutler- Hammer Manufacturing Co.). Feb. 3, 1916. Push-button systems; controllers, multiple-bar. -A motor is controlled from a push-button station arranged so that, with one setting of the buttons, starting, acceleration, and deceleration are controlled by the operation of the same button that, with another setting of the buttons, controls the connexions for inching. In the arrangement shown in Fig. 1, the motor A has series and shunt field-coils F, f, and its starting-resistance R is controlled by a multiple-arm starter 3 operated by a solenoid 4. The main switch 2 carries the main circuit contacts 2a and also contacts 2<b> which close a braking-circuit through a resistance 1 when the main circuit is open. Auxiliary contacts on the main switch are included in the actuating-circuit of the solenoid 4 and the maintaining-circuits of the switch 2 and solenoid 4. The arm of a shunt field rheostat R<1> can be set to any position corresponding to the speed required, and the relay 6 is normally closed to short-circuit it. A relay 7 also controls a shcrt circuit across the rheostat R<1> and has two windings connected to hold the relay closed during starting, while, during running, only one of the windings is connected in circuit and the relay then behaves as a vibratory regulator. The relay 8 normally closes a short circuit across the field resistance R<2> and has two windings carrying opposed currents during acceleration and running so that the relay is then inoperative; but the currents in the windings aid each other if the motor runs as a generator, and the relay then inserts resistance R<2> in the field circuit. The control station is provided with a button 29 with on and off positions, a button 24 which is normally on but may be locked off, and a button 25 with two sets of contacts and which may be locked in an off position intermediate between the two sets. To inch the motor, the button 24 is locked in its dotted-line position, the button 29 is moved to its on position, and the button 25 is depressed to bridge the contacts 28. This connects the main switch winding across the mains, and the switch closes to complete the motor circuit through all the resistance. For starting, the motor button 24 is returned to the positicn shown, and the button 25 is depressed to close the main switch. A maintaining-circuit for the main switch is completed through the contacts 10, 12 and button 24. The circuit of the starter solenoid 4 is completed through the contacts 11, 10, and the resistance R is cut out to speed up the motor. The starter arm 20 cuts out the series field coil F and the coil 7<a> of the relay 7. The push-button 25 may be set in its intermediate position so that acceleration stops at this stage, or it may be returned to its initial position to connect the contacts 27 to energize the relay 6 and place the rheostat R<1> in the field circuit. In the latter case, the motor may be decelerated at any time by depressing the button 25 to de-energize the relay 6. The motor is stopped by depressing the button 24 to break the maintaining-circuits. In the modification shown in Fig. 2, the button 102 controls the operating-circuits, and the button 100 controls the maintaining-circuits. The arm of the regulator 80 can be set at any point on the armature resistance R' or the field resistance R<2>, and a connexion to the arm is made through the contact of the relay 79 when the operation of the starter 78 has been completed. The starter carries a contact-arm 89 which normally short-circuits the field resistance included by the arm 80 to ensure a strong field at starting; the short circuit is opened when the starter operates. The motor is slowed up b depressing the button 102 to break the circuit of the solenoid 90 to allow the field resistance to be shortcircuited again. In another modification, the slowing-up is obtained by means of a separate relay.