US1454928A - Control system - Google Patents

Description

V M M May 15, 1923. 1,454,928

G. W. HURTT CONTROL SYSTEM Filed AUE- 1'7, 1920 Rev. Fwd.

. INVENTOR Georgewfiurfi ATTOR NEY WITNESSES: g. ca. M6 Mg Patented May 15, 19.23.

UNETED STATES GEORGE W. HUBTT, O13 VILKINSBUEG, PENNSYLVANIA, AsEIGNOB TO WESTING- HOUSE ELECTRIC & 1VIAN"UFACF VANIA.

RING COll'IPANY, A COBE'DBAEION OI PENNSYL- CONTROL SYSTEM.

Application filed August 1?, 1920.

To aZZ whom it may concern Be it known that I, GEORGE W. Honor, a citizen of the United States, and a resident of l/Vilkinsburg, in the county of Allegheny and State of Pennsylvania, have 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 control systems for accelerating motors.

One object of my invention is to pro vide a device for automatically shunting a starting resistance in series with a motor armature.

The second object of my invention is to so control a starting device that, upon reversing a motor equipped therewith, it will be certain to open 'any'shunt circuits around a starting resistance before the motor is operated in the opposite direction.

Hereto-fore, various devices have been pro vided for accelerating a motor that have been connected across the motor and a starting resistance therefor but if the motor was suddenly reversed, the devices did not al ways operate with sufficient rapidity to open the contactors which closed the shunt circuits across the starting resistance.

Briefly speaking, my invention consists in providing a relay having two actuating coils, one of which is connected across the starting resistor and the other of which is connected across the line whenever the motor is operating in a forward or in a reverse direction. This relay controls the closing of the contactors which shunt portions of the starting resistor.

For a better understanding of my inven tion, reference should be made to the acco1npanying drawings,

Fig. 1 of which is a schematic view of a motor control system embodying my inven tion;

Fig. 2 is a complete diagrammatic view of the control system shown in Fig. 1;

Fig. 3 is a sequence chart of well-known form showing the order in which the principal contactors of the control systems shown in Figs. 1 and 2 close.

Referring particularly to Figs. 1 and 2, a motor 21 having an armature 22, a series field-magnet winding 23 and a shuntfield magnet winding 24 may be electrically connected to supply conductors 25 and 26 which Serial No. 404,158.

are energized when a knife switch (not shown) is closed. A plurality of directional contactors l, 2, 3 and 4: control the forward and the reverse operation of the motor 21, in accordance with a familiar practice. Auxiliary contactors 3A. and 2e are mechanically connected to the directional contactors l and 3 and 2 and 4:, respectively. master controller 5 controls the operation of directional cont- actors 1, 2, 3 and l. A starting resistor 27 is arranged for series connection with the motor armature 22 and the series lield winding 23 and it may be shunted by closing contactors l1 and 12, which are normally open. A dynamic brak ing resistor 28 is electrically connected to the auxiliary contactors 2A and 3A. A field-circuit rhcostat 29 is connected in series with the shunt field-magnet winding- 2d.

The operation of my invention is as follows: lVhen the contact segment 30 of the master controller 5 is actuated to the forward position thereof, a circuit is established from supply conductor 25, through conductor 31, contact terminals 32 and 38, which are bridged by contact segment 2-50, conductor 34, actuating coil 35 of the con tactors 1 and 3, conductor 36, resistor 38 and conductor 39 to supply conductor 26. The completion of this circuit energizes the actuating coil 35 of the directional contactors l and 3 and the auxiliary contactor 3A, thereby causing contactors 1 and 3 to close and auxiliary contactor 3A to open.

When the directional contactors l and 3 are closed, a circuit is established from the supply conductor 25 through conductor 22, contact bridge 1, conductors L3 and armature 22, conductor 4 :6, contact bridge 3, conductors 48 and 49, starting resistor 27, conductor 53, series field-magnet winding 23 and conductors and 39 to supply conductor 26. The completion of this circuit energizes the motor 21 and causes it to operate in a forward direction, the shunt fieldmagnet winding 2 L being energized by a circuit from supply conductor 25 through conductor 56, resistor 58 of the field-circuit rheostat 29, field-magnet winding 2- and conductors 55 and 39 to supply conductor 26. r

The motor 21 is accelerated by closing the contactors 11 and 12. which establish shunt circuits across portions of the starting resistor 27. The contactors l1 and 12 are providedwith actuating coils 6i and 62, respectively.

The energization of the actuating coils 61 and 62 is controlled by a relay 63 that is provided with actuating coils 6 and 65. The relay 63 is further provided with two contact bridges 63a and 637) which are so arranged that contact bridge 63o completes a circuit con'iprising actuating coil 6i before contact bridge 63?) completes a circuit comprising actuating coil 62. The actuating coil 64 of relay 63 is energized by a circuit across the starting resistor 27, trom conductor 49 through conductor 66, actuating coil 64 of the relay 63 and conductors 69 and 70 to supply conductor 26.

The actuating coil 65 is electrically connected to the midpoint of the dynamic raking resistor 28 by conductor 71 and to supply conductor 26 by conductor 70. The coil 65 is energized only when either one of the auxiliary contactors 3A or 2A is closed and the other open; therefore, it will always be connected across the armature 22 and the starting resistor 27 when the master controller is in the forward or in the reverse position, but the coil 65 will be disconnected during dynamic braking and during the period of time that the controller 5 is in the oil position.

If, for example, the contactors l and 3 are closed, the circuit of the coil 65 extends from line conductor 25 through conductor contact bridge 1a conductors t3 and 73, contact bridge QAa, holding coil 75, halt of the dynamic-braking resistor 28, conductor Tl, actuating coil 65 and conductor '70 to supply conductor 26.

The completion of both. of the circuit which energize actuating coils 64 and 65 cause the contact bridges 63a and 63b to rise, until the contact bridge 63a assumes its closed position, thereby establishing a circuit from the conductor 49, through conductor 66, actuating coil 61 of the contactor ll, conductor 'T8,(:onta(:t bridge 63a and coi'iductors 69 and 70 to supply conductor 26. When the actuating coil 61 is energized, it causes the contactor ll to close, thereby establishing a main circuit from conductor at) through conductor 81, contact bridge llc: and conduc tor 83 to the mid-point oi the starting rc sister 27.

When the relay 63 has been su'llicient ly cne'rgized to continue the upward movement ot the contact bridges 63a and 636, (the contact termim ls which engage the contactbridge 63a bin 1g slightly movable) thc contact disk 6532) establishes a circuit from the conductor 83 through conductor 84. actuating coil 62 ot' the contactor l2. conductor 86, contact bridge 63?) and conductors 69 and 70 to supply conductor 26. The actuating coil 62 isenergized. when this circuit 0+ tablished, and it causes the contactor l3 to close, thereby shunting the portion ot' resistor 27 that is still in series with the armature 22 by a circuit extending from the conductor 83 through conductor 88, contact bridge 12a and conductor 89 to the righthand end of the starting resistor 27. The motor 21 is thus accelerated by shunting portions of the starting resistor 27 and, when the contactors 11 and 12 are closed, the motor 21 is brought to full speed.

The actuating coil 6%, which is energized by the difference in potential across the starting resistor 27, is practically de-ener ized, when the contactors Ill and 12 are c'osed', and the relay 63 would open, if the associated actuating coil 65 were not sufilciently powerful to maintain it in its closed pOsI- tion.

The circuit which energizes the actuating coil 65 of the relay 63 extends through contact bridge la of the contactor l and will be broken when the master controller 5 is a'ctuated from the forward position, thereb causing the relay 63 to open. In this eien both the actuating coil 6]. of the contactor 1'1 and the actuating coil 62 of the contactor. 12 are de-energized and, consequently, the contactor-s ll and 12 open, thereby breaking the shunt circuit across the starting resistor 27.

\Vhen the contact segment 30 of the inaster controller 5 is actuated into the reverse position, a circuit is established from the supply conductor 25 through conductors 31 and 90, contact terminals 91 and 922, which are bridged by contact segment 3'0, conductor 93, actuating coil ill of the directional contactors 9 and 4 and auxiliary contactor 2A, conductors 95 and 36, resistor 38 and conductor 39 to supply conductor 26. The actuating coil 9%, being thus energized, causes the contactors 2 and at to close and the contactor 2A to open, thereby establishing 21 ch",- c-uit from the line conductor 25 through conductors 56 and 96, contact bridge 4A, conductors 97 and l6, armature 22, conductors 45, 4:3 and 98, contact bridge 2a, conductor L9, resistor 27, conductor 53, series fieldmagnet winding 23 and conductors and 39 to supply conductor 26.

The motor 21 is operated in a reverse direction by the completion of this circuit, since the direction of energizationof the series field-magnet winding 23 and of the Sllimt field-magnet winding 24 is the same as when the motor 21 is operated in a forward direction, and. the direction of the current through the armature 22 only is changed.

The :-=tartii;g resistor 27 is gradually shortcircuited in the same manner as when the motor is operated in a forward direction, ince the actuating coil 64 of the relay 63 is connected across the starting resistor as has been previously described.,and the actu ating coil of the relay 63 is connected the supply conductors 25 and The actuating coil is energized by a circuit its which is established from the line conductor 25, through conductors. 56 and 96, contact bridge la, conductors 9?, l6 and 100, contactor bridge 3Aa, holding coil 102 of the contact 3A, conductor 103, half of the dynamicbraking resistor 28, conductor Tl, actuating coil 65 and conductor to supply conductor 26.

The operation of the relay (S5 is the same as during forward operation of the motor, as the actuating coils 6st and 65 are energized to the same degree. When the master controller 5 is reversed, in this case by moving the contact segment 30 to the forward position, the actuating coil 9% of the directional contactors 2 and 4, and the auxiliary contactor 2A is die-energized, thereby causing the contactors 2 and 4 to open and the auxiliary contactor 2A to close. The relay 63 will open, as the actuating coil 65 will be tie-energized by the contactor 4: opening. WVhen the relay 63 is opened, the actuating coils 61 and 85 of the contactors 11 and 12, respectively, are tie-energized and the contactors 11 and 12 open.

From the above description, it is apparent that apparatus designed in accordance with my invention is relatively simple and economical in construction and positive in operation. With such a system, it will be impossible to reverse a motor so rapidly that the contactors in the shunt circuit across the starting resistor will not have time to open, thereby preventing injury to the motor, since it cannot be connected directly across the line.

While I: have shown my invention in a preferred form, it is apparent that modifications in the apparatus and in the arrangement of the circuits may be made 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 a motor, of means for accelerating said motor, means for effecting the reversal thereof, and means connected. across said motor only during certain operative periods thereof in accordance with the condition of said reversing means, for restoring said accelerating means to its initial condition.

2. The combination with a motor having an armature and means for effecting dynamic braking thereof, of means comprising a relay for accelerating said motor, said relay being electrically connected to said armature and to said braking means during certain operative periods of said motor.

3. The combination with a motor having an armature and means comprising a resister for effecting dynamic braking thereof, of means comprising a relay for accelerating said motor, said relay being electrically connectcd across both said armature and said resistor during accelerating periods of said motor.

in a motor control system, the combination with a motor and means for reversing said motor, means comprising a resistor for effecting dynamic braking of said 1110- tor, means for starting said motor, and means connected to said resistor for controlling said starting means.

5. In a motor control system, the combination with motor, means comprising a re sistor for accelerating said motor, and means comprising a resistance device for effecting dynamic braking of said motor, of means comprising a relay having an actuating coil for operating said accelerating means, said relay having its actuating coil permanently connected to said device.

6. in a motor control system, the combination with a motor having an armature, a plurality of contactors therefor and a dynamic braking circuit for said motor, of a starting resistor and means comprisin a relay for shunting said resistor, said relay being electrically connected to said dynamic braking circuit by said contactors and across said motor during certain operative periods thereof.

'7. In a motor control system, the combination with a motor having an armature, and a plurality of directional contactors therefor, of a dynamic braking circuit, a plurality of auxiliary contactors coacting with said directional contactors for conecting said braking circuit to said armature, a starting resistor, a contactor for shunting said starting resistor, and a relay for controlling said shunting contactor, said relay being connected to said dynamic braking circuit and across said armature.

111 a motor control system, the combination with a motor having an armature, Y

and a plurality of directional contactors therefor, of a dynamic braking circuit, a. plurality of auxiliary contactors coacting with said directional contactors for connecting said braking circuit to said armature, a starting resistor, a plurality of contactors for shunting said starting resistor, and relay for controlling said shunt contactors, said relay being provided with two actuating coils, one being electric-ally connected to said dynamic braking circuit and across said armature and said starting re sistor, the other coil being connected across said starting resistor.

9. In a motor control system, the combination with a motor having an armature and a dynamic braking circuit therefor, of means comprising a resistor for accelerating said motor and a relay having two actuating coils, one of said coils being electrically connected across said resistor and the other of said coils being connected to said dynamic comprising a resistor for effecting dynamic 10 braking of sand motor, and relay means for ensuring the opening of said switch before the closure of an initially open contactor during the reversal of said motor, said relay means being, connected across a portion of said dynanlie-braking resistor.

in testimony whereof, I have hereunto subscribed, my name this 5th day of August 1920.

(monen W. IIUR'IT.

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