US1242910A

US1242910A - Motor-control system.

Info

Publication number: US1242910A
Application number: US4399415A
Authority: US
Inventors: Howard L Beach
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1915-08-06
Filing date: 1915-08-06
Publication date: 1917-10-16
Anticipated expiration: 1934-10-16

Description

H. L. BEACH.

MOTOR CONTROL SYSTEM.

APPLICATION HLED AUG-6, 915.

1,242,910. Patented Oct. 16, 1917.

FILE; mvsrqma Haw/arc! 1;. fieirach UNITED STATES PATENT OFFICE.

HOWARD I1. BEACH, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVAN IA.

MOTOR-CONTROL SYSTEM.

Specification of Letters Patent.

Patented Oct. 16, 1917.

Application filed August 6, 1915. Serial No. 43,994.

To all whom it may concern:

Be it known that I, HOWARD L. BEACH, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State otPennsylva'nia, have invented 'a' new and useful Improvement in Motor-Control Systems, of which the following is a specification.

My invention relates to motor-control systems, and it has for its object to provide a simple and efiective means for controlling the speed of electric motors during their acceleration, operation and retardation.

Motor-control systems of the same general character as that of my invention have, heretofore, been provided with series and shunt controlling circuits which comprised resistors to be so controlled as to vary the speed of the motors between desired limits. In such arrangements, it has been necessary to provide switching mechanisms of a somewhat complicated nature to control the re 'sistors. It has been customary, also to decrease the resistance of either of the controlling circuits by shunting the resistors injcluded therein.

In accordance with the present invention, I provide a plurality of resistors which are connected in shunt relation to the motor armature. The usual series or starting resistor'is controlled by accelerating switches in the usual manner. By means of a simple arrangement, the shunt resistors are successively transferred from the shunt circuit to a series connection iii-parallel with the starting resistor. The effect is to gradually increase the resistance of the shunt circuit and to decrease the resistance in series with the armature, winding. By properly arranging the several circuits, the speed of the motor may be controlled as desired and the motor may be 'causedto operate uniformly at relatively low speeds.

In the accompanying drawings, Figure 1. is a diagrammatic view of circuits and apparatus embodying my invention. Fig. 2 is a diagrammatic view of a schematic arrangement of the system of Fig. 1. Figs. 3, 4, 5, 6 and 7 arediagrammatic views illustrating the circuits as arranged inaccordance with successive positions of the controller.

Line conductors l and, 2, which may be connected to any suitable source of direct current, supply energy to an electric motor having an armature winding 3 and a shunt field winding 4. A shunt circuit for the armature winding comprises

resistors

5, 6 and 7 which are adapted to be connected in parallel with each other. The connections of the

resistors

5, 6 and 7 are respectively controlled by electromagnetic switches 8, 9 and 1G, each of which is provided with a shunt actuating coil 11.

A sectional starting resistor 12, which is in series with the motor armature, is controlled by a series of progressively actuated

switches

13, 14 and 1 The switch 18 is provided with a shunt actuating coil 16 while the switches 1 1 and 15 are provided with series actuating coils 17. Each of the switches for controlling the resistor 12 is provided with series holding coils 18, each of which, except that of switch 15, is in series with the actuating coil 17 of the succeeding switch to close.

A controller 19, or master switch, comprises a contact segment 20 which successively engages a plurality of contact members 21 for producing the operation of the several electromagnetic switches in their proper sequence, as will be later described.

To start the motor, a line switch 22 is first closed. The controller handle is then actuated to the left, as viewed in Fig. 1, to engage the first contact member 21 ancl thereby complete a circuit comprising the actuating coil 28 or" a main switch 24. The latter then closes to complete the armature circuit for the mot-or which extends from the positive line conductor 2 through line switch 22, main switch 24, armature winding 3, starting resistor 12, and main switch 22 to lineconductor 1. A low-resistance shunt circuit for the armature winding 3 comprises the

resistors

5, 6 and 7 which are connected in parallel with each other. The electrical con nections that are established by the controller in its first position are diagrammatically shown in Fig. 3. The motor then operates at a low rate of speed, because of the low-resistance shunt circuit for the armature.

In the second position of the controller, the coil 11 of the electromagnetic switch 8 is energized to actuate the latter to its upper position and thereby disconnect the resistor 5 from the shunt circuit and connect it in series with the armature winding 3 but in parallel with the resistor 12. The several circuits are now arranged in accordance with the diagram of Fig. a. The removal of the resistor 5 from the shunt circuit operates, in effect, to. increase the resistance of the shunt circuitand thereby cause an increasedcurrent to traverse the motor winding. The connection of the resistor in parallel with the resistor 12 serves to decrease the resist ance of the series circuit and thereby accelerate the motor.

The actuation of the controller to its third and fourth positions operates, in ya similar manner, as successively transfer the

resistors

6 and 7 from the. shunt circuit to the series. circuit, the resistors Sand 7 being connected in parallel with the resistors 12 and and witheach other. The circuits ob taining ii the respective positions of the controller 19 are illustrated in Figs. 5 and (3. The resistance of the shunt circuit is gradually increased, and the resistance of theseries circuit is gradually decreased, by the changes in connections above described, andthe motor speed is increased to a corresponding degree.

The actuation of the controller arm 19 to its final position completes a circuit for the actuating coil 16 of switch 13. The latter then closes tocomplete a circuit through the holding-coil 18 and the actuating coil. 17 of switch 11 for shunting one of the sections of the resistor 12. The switches 11 and 15 then close in order to complete a shunt circuit for the resistor 12 and thereby further accelerate the motor to its normal, speed. The shunting of the resistor 12 operates to establish a shunt, circuit for the resistors 5, (tand 7,

When it is .desired to reduce the speed of the motor, the controller handle may be actuated in theopposite direction to that previouslydescribed and, allowed to remain at any. intermediate position. It will he, noted that the resistor 12 is shunted during the operation ofthe motor, since the holding coil 18 of switch 15 is in series with the motor armature- The return of the controller arm toward its illustrated or inoperative position will not operate to insertthe resistor 12 in series with the motor armature until the main switch 24 is opened to break the circuit of the coil 18.

hen the controller arm is in its third position, the circuit of the actuating coil v11 of the switchlO has been opened, and the latter ,assumesits illustrated position to disconnect the resistor 7 from the series circuit and connect it in parallel with themotor armature. The counter-electromotive force of the motor thencauses current to traverse the shunt circuit thus established, andthe speed of the motor is accordingly decreased. In a similar. manner,.when.the controller is actuated to its second and first positions, the resistors. 6 and 5 are successively transferred from theseries circuit to the shunt circuit and are again connected in parallel with each other. The reduction of resistance in the shunt circuit causes an increased current to. traverse it, and the speed of the motor is reduced in a corresponding degree.

hen the shunt circuit comprises the

resistors

5, 6 and 7 connected in parallel with each other, the motor operates uniformly at a comparatively low rate of speed. This condition is especially desirable in connection with hoists, elevators and similar ma chines in which it is. desirable tooperate. at a low rate of speed; before the motor is brought toa stop. Tostop the motor, when it isoperating under the conditions just described, it is only necessary to return the controller-to its off position. The motor then operates as a generator, and. current traverses the shunt circuit comprising the resistors 5, G and 7 to efiect the dynamic r k n of the mice To bring the DIQtOI' QHlQklY to rest when it is operating at a comparatively highrate of speed, the controller handle may be returned to its olf position, through the various, intermediate positions, to succes; sively connect theresistorsfi, 6 and 7 in-,the sh uit circuit-and to open the main switch 24, The dynamic braking action, which is thereby produced, may he graduated byad j usting the controller in accordance with the motor speeghorthe maximum effect maybe obtained by returning the controller to its .ofl'? positioutoreduce the resistance of the dynamic braking circuit to a minimum.

In the operation of the system as above described, itwill :be noted that the circuits of the shunt-connected;resistors are not merely opened .to increase the resistance of;the shunt circuit, hutare transferred bodily frornpne circnitto another by. means ofI double-threw switches. By; means of the arrangement above described, I am enabled to gradually accelerate thespeed; of the motor and to cause the latter to ouerate at variousspeeds corresponding to the arrangement of the er ral, ir uits- 1 tml i h r nab ed to bring themotor safely and gradually to rest u nta-s i m s ixw p y a y: namic braking action, the eftect of which is within thecontrol of the operatorv WYhile, the n otone nbodied in the control system has been shown and described asheserating .inone direction. only, it will beo ews tha the P in ipl o 1 my nt n is qu l y. pr ca ele a m e p v de with reyersing meanssuch as. is commonlye131,- ployed in connection with; eleyators, hoists and similarmachines. It is understood, that such changes maybe made, without depart, ing from, thespirit of my invention, as .fall within thescope ofi-the appended claims,

I claim .as my invention 1.,- In a motor-controlsystem, the combination with an electric motor, and a pin, {Q0

rality of resistors in parallel relation to the armature of said motor, of means for successively connecting said resistors in series relation to the motor armature and in parallel relation to each other.

2. In a motor-control system, the combination with an electric motor, and a plurality of resistors in parallel relation to the armature of said motor and in parallel relation to each other, of means for successively connecting said resistors in series relation to said armature and in parallel relation to each other.

3. In a motor-control system, the combination with a shunt-wound electric motor, a resistor in series relation to the motor armature, and a second resistor in parallel relation to said armature and in series relation to the other resistor, of means for successively connecting the second resistor in series with the motor armature and in parallel relation to the other resistor and shunting said other resistor.

4. In a motor-control system, the combination with a shunt-wound electric motor and a resistor, of means operable, according to its position, to connect said resistor either in parallel or in series relation to the armature of said motor, and means for controlling said connecting means.

5. In a motor-control system, the combination with an electric motor, and two circuits that are respectively in series and in parallel relation to the armature of said motor and in series relation to each other, of a resistor, and means for transferring said resistor from one circuit to the other.

6. In a motor-control system, the combination with a shunt-wound electric motor, and two circuits that are respectively in series and in parallel relation to the armature of said motor, of a resistor in each of said circuits, and means for successively transferring one of said resistors from the one circuit to the other in parallel relation to the other resistor and shunting said other resistor.

7. In a motor-control system, the combination with an electric motor having an armature and a field-magnet winding, and two circuits that are respectively in series and in parallel relation to said armature and in series relation to each other, of a resistor in each of said circuits, and means for controlling one of said resistors whereby it is transferred to the other circuit in parallel relation to the other resistor.

8. In a motor-control system, the combination with an electric motor, a resistor in series relation to the armature of said motor, a plurality of resistors in parallel relation to said motor armature and to each other, of means for successively connecting each of said parallel-connected resistors in parallel relation to said series-connected resistor.

9. In a motor-control system, the combination with an electric motor, a resistor in series relation to the armature of said motor, a plurality of resistors in parallel relation to said motor armature and to each other, of means for successively connecting each of said parallel-connected resistors in parallel relation to said series-connected resistor and for shunting said series-connected resistor.

In testimony whereof, I have hereunto subscribed my name this 21st day of July,

- HOWARD L. BEACH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C.