US1461512A - Control system - Google Patents

Description

July 10, 1923. 1,461,512 5. M. BQUTQNW 7 CONTROL SYSTEM Filed Sept. 17. 1920 46 so L /aa 5a 1 az m a/ 495053 52 f nrwara fie verse 74 Reverse Forward a4 7 .92 a 2 l 30 i a0 7 /02 a ,m/

WITNESSES: INVENTOR 427% Edgar M Baum/z .7 M M BY ATTORNEY Patented July 10, 1923.

UNITED STATES PATENT OFFICE.

EDGAR H. BOUTON, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- vnnm.

CONTROL SYSTEM.

Application filed September 17, 1920. Serial No. 410,906.

To all whom it may concern:

Be it known that I, EDGAR M. BoUToN, a citizen of the United States, and a resident of Wilkinsburg in the county of Allegheny and State of l ennsylvania, bar e. invented a new and useful Improvement in Control Systems, .of which the following is a specification.

My invention relates to motor-control systems and it has particular relation to systems for accelerating motors by means of contactors which are closed in accordance with the counter electromotive force of the motors.

One object of my invention is to provide means for automatically shunting the starting resistor of a motor and to provide means for preventing the shunting of the resistor during electrical braking.

A second object of my invention is to provide means for preventing the starting of a motor through the auxiliary contacts which close a line circuit-breaker therefor.

Heretofore the starting resistor in series with the motor has been automatically shunted by contactors controlled by the counter-electromotive force generated by the motor.. The'disadvantage of this method, when'the motor is plugged or suddenly reversed to effect electrical braking, is that the starting resistor is prematurely shunted by the closure of the contactors that are controlled by the counter electromotive force, thereby causing excessive current to traverse the armature circuit of the motor.

Briefly speaking, my invention consists in providing a contactor having an actuating coil for shunting the. starting resistor, the actuating coil being connected in shunt re lation across the armature and one-half of the starting resistor, and secondly, in pro-. viding resistance in series with both the start and the stop buttons, which control the line circuit-breaker for the motor, thereby diminishing the current passing therethrough and preventing a. heavy rush of current through the armature.

For a better understanding of my inven tion, reference should now be made to the accompanying drawings, 7

Fig. 1 of which is a diagrammatic view of a motor-control system. embodying my invention;

Fig. 2 is a schematic diagram of the motor-control system shown in Figs. 1 and 3;

field-magnet winding 2 of, the motor 1.

Fig. 3 is a diagrammatic view of a control system similar to that shown in Fig. 1.

Referring particularly to Figs. 1 and 2, a motor 1' having a shunt field-magnet windmg 2, a series field-magnet winding 3 and an armature 4, is energized from supply conductors 5 and 6, through a knife switch 7. A master controller 8 is provided for reversmg the current through the armature 1 of the motor 1. A field rheostat 9 is provided for controlling the strength of the shunt A starting resistor 10, which is connected in series relation with the motor armature 4,

may beshunted by the closing of a contactor 11.

A three-pole contactor or circuit-breaker 12, having an actuating'coil 13, is governed by a start push-button switch 14 and a stop push-button switch 15. A resistor 16 is connected in series relation with the start push-button switch 14 and a resistor 17 is connected in series relation with the stop push-button switch 15.

The operation of the s stem is begun by closing the knife switch i and pushing the start push-button 14. These actions establish a circuit from supply conductor 18 through resistor 16, contact member 20 of start push-button 14:, conductor 21, actuating coil 13 of circuit-breaker 12, and conductor 23 to knife switch 7. The completion of this circuit energize the actuating coil 13 sufficiently to close the circuit-breaker 12.

When the circuit-breaker 12 is closed, a holding circuit therefor is established from the knife switch 7 through conductor 18, contact members 24 and 26 of circuit-breaker 12, resistor 17, contact member 28 of stop push-button 15 in its normal closed position, conductor 21, actuating coil 13. of the circuit-breaker 12 and conductor 23 to knife switch 7. a

The circuit-breaker 12 being closed, the master controller 8 may be so actuated as to operate the motor in either the forward or the reverse direction. By moving the controller from its off position to its forward position, the motor is operated in the forward direction, by a circuit which is established from the knife switch 7, through conductor 18, contact member 24 of the circuitbreaker 12, conductor 29, series field-magnet winding 3, conductor 30, contact terminals 31 and 33, which are bridged by contact I segment 32 of the master controller 8, conductor 34, armature 4 of the motor 1, conductor 35, contact terminal 36, contact segment 37, contact terminal 38, conductors 39 and 40, starting resistor 10 and conductors 41 and 23 to the knife switch 7.

Concurrently with the energization of the series field-magnet winding 3, the shunt field-magnet winding 2 is energized by a circuit that extends from knife switch 7 through conductor 18, contact member'24 of the circuit-breaker 12, conductor 25, shunt field-magnet winding 2 of the motor 1, conductor 44, field rheostat 9 and conductors 45 and 23 to the knifeswitch 7. The armature 4, the shunt field-magnet winding 2 and the series field-magnet winding 3 of the motor 1 are now energized.

When the start button 14 is pushed, besides establishing a circuit through the actuating coil 13 of the circuit-breaker 12, a second circuit is established, if the master switch 8 is in its forward position, from knife switch 7 through resistor 16, contactmember 20 of start button 14, contact member 28 of stop button 15, resistor 17, contact member 26 of circuit-breaker 12, conductors 25 and 29, series field-magnet winding 3, conductor '30, contact terminal 31, contact segment 32, contact terminal 33, conductor 34, armature 4 of motor 1, conductor 35, contact terminal 36, contact segment 37, contact terminal 38, conductors 39 and 40, resistor 10, conductors 41 and 23 to knife switch 7. If the resistors 16 and 17 were not in series with the start pushbutton switch 14, a heavy rush of current would take place through the push-button, as it is connected through the armature 4 of the motor 1 across the supply conductors 5 and 6.

The starting resistor 10 is shunted by the contactor 11, which is operated by an actuat'ing coil 46. The actuating coil 46 is connected across the series field winding 3, the armature4 and approximately half of the starting resistor 10 when the master controller 8 is in either its forward or its reverse position.

When the master controller 8 is in its forward pos tion, a circuit is established from knife switch 7 through conductor 18, contact member 24 of circuit-breaker 12, conductor 25, contact member 47 of circuitbreaker 12, conductor 48, contact terminal 49 of the master controller 8, contact segments 50 and 51, which are electrically con nected, contact terminal 52, conductor 53,

actuating coil 46 of the contactor 11, conductor'54, a portion of starting resistor 10 and conductors 41 and 23 to knife switch 7.

The actuating coil 46 is set to close the contactor 11 when energized at a higher current value than if it were connected only across the armature 40f the motor 1. When the counter electromotive force of the motor 1 energizes the actuating coil 46 of the contactor 11 sufficiently, corresponding to suitable accelerating conditions, the contactor 11 will close, thereby shunting the starting resistor 10 to complete the acceleration of the motor.

WVhenever the controller 8 is moved to the reverse position, a circuit is thereby established for the series field-magnet winding 3 and the armature 4. This circuit extends from knife switch 7 through conductor 18, contact member 24 of circuit-breaker 12, conductor 29,. series field-magnet windings 3 of the motor 1, conductor 30, contact terminal 31 of the controller 8, segments 58 and 59 which are electrically connected, contact terminal 36, conductor 35, armature .4 of the motor 1, conductor 34, contact terminal 33 of the controller 8, contact segments 60 and 61, which are electrically connected, contact terminal 38, conductors 39 and 40, starting resistor 10 and conductors 41 and 23 to the knife switch 7.

The completion of this circuit causes the rotation of the armature 4 of the motor 1 in the opposite direction, as both the shunt field-magnet winding 2 and the series fieldmagnet winding 3 are energized in the same direction as they were during the forward operation of the motor 1 and only the directiOIl of the current through the armature has been reversed.

Another circuit is established at this time for the actuating coil 46 of the contactor 11 from the knife switch 7, through conductor 18, contact member 24 of the circuit-breaker 12, conductor 25, contact member 47 of the circuit-breaker 12, conductor 48, contact terminal 49 of the master controller 8. contact segments 62 and 63 which are electrically connected, contact terminal 52, conductor 53, actuating coil 46 of the contactor 11, conductor 54, approximately one half of the starting resistor 10 and conductors 41 and 23 to the knife switch 7.

When the counter electromotive force of the motor 1 energizes the actuating coil 46 of the contactor 11 sufiiciently, the contactor 11'will close, there-by shunting the starting res stor 10, as previously set forth.

If the master controller 8 is suddenly actuated from its forward position to its reverse position or vice versa, electrical braking or plugging of the motor 1 is effected. It is necessary to have the startingresistor 10 in series with the motor and the contactor 11 open to prevent a heavy rush of current through the armature 4.

In a system arranged in accordance with my invention, the proper procedure is ensured, since the contactor 11 will not close until after the motor 1 has begun to actually operate in a reverse direction and build up its counter electromotive force. The

motor 1 would energ'ze the actuating coil 46 sufliciently to close the contactor 11, if it were not balanced by the drop in potential across that portion of the resistor 10 which is between the armature 4 of the motor 1 and the point where the conductor 54 is electrically connected to the starting resistor 10.

Referring to Fig. 3, the motor 1 having shunt field-magnet winding 2, series fieldmagnet winding-3 and armature 4 is electrically energized from the line conductors 5 and 6 through the knife switch 7. The energization of shunt field-magnet winding 2 is controlled by the rheostat 9. The starting resistor 10 is-in series with the armature 4 of the motor 1.

The motor 1 is started directly from a master controller 7 0, which controls the forward and the reverse operation of the motor 1. A no-voltage release device 71 is connected in series relation with the armature 4 of the motor 1 and prevents the operation of the motor 1 upon failure ,of the line voltage. The contactor 11 isprovided for shunting the starting resistor 10 during the starting of the motor 1.

The operation of the control system is begun by closing the knife switch 7. The ac- -'tuating coil 73 of the no-voltage release device 71 is energized by a circuit that extends from the knife switch 7 through conductors 74 and 75, contact terminal 76 of the controller 70, contact segment 77, contact terminal 78, conductor 79, contact terminal 80,

conductor 81, series field-magnet winding 3 of the motor 1, conductor 82, resistor 84, actuating coil 73 of the device 71, and conductor 86 to the knife switch 7. When this circuit is completed, the device 71 is closed by the actuating coil 73.

A holding circuit for the device 71 is provided from the knife switch 7.through conductors 74 and 87 contact member 88 of the device 71, conductor 89, resistor 84, actuating coil 73 of the device 71 and conductor 86 to the knife switch 7. When the voltage through the actuating coil 73 falls below a predetermined value, the device 71 opens and the holding circuit is thereby broken. It

is possible to close the device 71 only by bringing the master controller to the off position shown in the drawing.

The device 71 and the knife switch 7 being closed, the motor 1 may be operated in a forward direction byactuating the master controller 70 to its forward position. A circuit is established thereby from the knife switch 7 through conductors 74 and 87, contact member 88 of the device 71, conductors 89 and 82, series field-magnet winding 3 of the motor 1, conductor 81, contact terminal 80 of the controller 70, contact segment 90, c n act terminal 91, conductor 92, the armature 4 of the motor 1, conductor 93, contact terminal 94 of the controller 7 0, contact segment 95, contact terminal 96, conductor 97, the starting resistor 10 and conductor 99 to the knife switch 7.

The shunt field-magnet winding 2 of the motor 1 is energized as soon as the device 71 isclosed by a circuit established from the knife switch 7, through conductors 74 and 87, contact member 88 of the contactor 71, conductors 89 and 82, shunt field-magnet winding 2 of the motor 1, conductor 101, field rheostat 9 and conductors 102 and 86 to the knife switch 7. The motor 1 is operated in a forward direction as soon as the armature 4, the series field-magnet winding 3 and the shunt field-magnet winding 2 are energized.

In addition, when the master controller 70 is moved to its forward position, a circuit for the actuating coil 103' of the contactor 11 is established from the knife switch 7 through conductors 74 and 87, contact member 88 of the contactor 71, conductors 89 and 82, series field-magnet winding 3, conductor 81, contact termlnal 80, conductor 79, contact terminal 78 of the controller 70, contact segments 77 and 104, which are electrically connected, contact terminal 105, conductor 106, actuating coil 103 of the contactor 72, resistor 107, conductor 108, approximately half of the starting resistor 10 and conductor 99 to the knife switch 7.

When the counter electromotive force of the motor 1 is sufficient to so energize the actuating coil 103 of the contactor 11 that it closes the contactor 11, the starting resistor 10 is shunted to complete the motor acceleration.

By placing the resistor 107 in series with the actuating coil 103 of the contactor 11, a relatively high counter electromotive force is required to energize the actuating coil 103 sufiiciently to close the contactor 11, as previously explained.

Whenever the master controller 70 is moved to its reverse position, a. circuit is established from the knife switch 7 through conductors 74 and 87 contact member 88 of the device 71, conductors 89 and 82, series field-magnet winding'3, conductor 81, con tact terminal 80 of the controller 70, contact segments 112 and 113, which are electrically connected, contact terminal 94, conductor 93, armature 4 of the motor 1, conductor 92, contact terminal 91 of the controller 70, contact segments 114 and 115, which are electrically connected, contact terminal 96, conductor 97. starting resistor 10 and conductor 99 to the knife switch 7.

The motor 1 will now operate in a reverse direction, as the current through the armature 4 thereof has been reversed, while the energization of the series field-magnet winding 3 and the shunt field-magnet winding 2 is in the same direction as for forward opere ation of the motor 1.

In addition, when the master controller 70 is actuated to its reverse position, the actuating coil 103 of the contactor 11 is electrically connected in shuntrelation to the armature 1 and a portion of the starting resistor 10, by a circuit established from the knife switch 7 through conductors 74 and 87, contact member 88 of the device 71, conductors 89 and 82, series field-magnet winding 3 of the motor 1, conductor 81, contact terminal 80, conductor 79, contact terminal 78 of the controller 70, contact segments 77 and 116, which are electrically connected, contact terminal 105, conductor 106, actuating coil 103 of the contactor 11, resistor 107, conductor 108, approximately half of the starting resistor 10 and conductor 99 to the knife switch 7. As soon as the counter electromotive force of the motor 1 has sufficiently energized the actuating coil 103, the contactor 11 will close.

The contactor 11 will not close if the master controller is suddenly reversed, to plug the motor, until the counter electromotive force has been built up in the opposite direction. The drop in potential across that portion of the starting resistor 10 which is between the armature 4 and the point Where the conductor 108 is connected to the starting resistor counter-balances the generator effect of the armature 4 of the motor 1 to prevent sufficient energization of the actuating coil 103 to close the contactor 11.

From the above description, it is apparent that I have provided means for closing a circuit-breaker in series with a motor and for maintaining it. closed, and that such means is protected from a heavy rush of current through the motor 1. I have also provided means for automatically shunting the starting resistor of a motor which will only operate after the motor has been brought to a predetermined speed in either a forward or a reverse direction and protective means for preventing the. shunting of the starting resistor when the motor is used for electrical braking.

While I have shown my invention in a preferred form, it is apparent that minor modifications may be made in the apparatus and arrangement of the control circuits without departing from the spirit thereof. I desire therefore, to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a motor-control system, the combination with an electrical device, a switch for starting said device and means comprising an actuating coil for closing said switch, means for energizing said coil, means electrically connected to said device for maintaining said coil energized after the closing of said switch, and means for preventing the starting of said device through said maintaining means.

2. In amotor-control system, the combination with an electrical device, a switch for starting said device, means comprising an actuating coil for closing said switch,

means for energizing said coil, means comprising a holding circuit in shunt relation to said electrical device for maintaining said coil energized, and meals for preventing the starting of said device through said energizing. means and said maintaining means.

3. In a motor-control system, the combination with a motor, a contactor for energizing said motor, and an actuating coil operating saidcontactor, of means for energizing said coil, means for maintaining said coil energized, and means for preventing the starting of said motor through said energizing means.

4. In a motor-control system, the combination with a motor, a contactor for energizing said motor, and means comprising an actuating coil for operating said contactor, of means for energizing said coil, a resistor in series with said means, and means independent of said resistor for maintainingsaid actuating coil energized after the closing of said contactor.

5. In a motor-control system, the combination with a motor, a contactor for energizing said motor and means comprising an actuating coil for operating said contactor, of means for energizing said coil, a resistor in series with said energizing means, and a holding circuit comprising a second resistor for maintaining said actuating coil energized independently of said first resistor.

6. In a motor control system, the combination with a motor, of a contactor having an actuating coil for energizing said motor, a resistor, a switch associated with said resistor for energizing said coil and means comprising a second resistor for maintaining said coil energized, said first and second resistor being connected in parallel relation during the concurrent operation of Said switch and said contactor.

In testimony whereof, I have hereunto subscribed my name this 14th day of September, 1920.

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