US1392059A - Control system - Google Patents

Description

H. 0. JAMES. CONTROL SYSTEMJ" APPLICATION FILED JUL 81 19:19.

Patntedsept. 27,1921.

WITNESSES": 62. W

INVENTOR Hang/Z2 Jamar BY ATTdRNEY UNITED STATES PATENT OFFICE.

HENRY D. JAMES, OF EIlGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTING- .HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

con'rnor. SYSTEM.

T 0 all whom it may concern:

Be it known that I, HENRY D. JAMES, a citizen of the United States,,and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, haveinvented a new and useful Improvement in Control Systems, of which the following is aspecification. 1

My invention relates to control systems of general application but more particularly to motor-control systems of the type illustrated and described in my copending application Serial No. 236,937, filed May 27, 1918, 1n which a plurality of contactors for short-' circuiting the accelerating resistor are adapted to be closed by relays which are, in turn,

controlled by'an energizing coil in parallel circuitwith the resistor.

As the energizing coil becomes short-circuited, and, therefore, ineffective, upon the short-circuiting of the resistor, some means must be provided for maintaining the re sistor-short-lcircuiting contactors closed. In the said copending application, I effect this result with the aid of an additional coil.

' An object of my presentinvention is to provide an improved motor-accelerating system of the above-described character which shall dispense with the additional coil.

One method of preventing connecting the motor; directly across the line without the accelerating resistor iii-circuit with the motor armature, upon the motor being stopped and immediatelyrestarted, or after voltage failure andthe return of voltage to the line, is toprovide for preventing the-closing of the motorcircuit until the. resistor-short-i circuiting contactors all occupy their open positions. In the above-mentioned application and in another copending application, Serial No. 249,344, filed August 10,1918, 1* have illustrated several ways of attaining this result.

A second object of my invention is to provi'dea novel accelerating system for. accomplishing the above-mentioned result in a new and improved way. r Other and further objects of my inventio will appear hereinafter.

According to the present invention, the actuating coil ofthe line con-tactor is adapted to beenergized by a circuit'comprising a switch that is mechanically connected to the relay which controls the first contactor to.close.-* I This relay is shunted by a resistor Specification of Letters Patent. Patented Sept, 27, 1921 Application filed January 8, 1919. Serial No. 270,148.

of high resistance which reduces the current traversing the line contactor coil so as to prevent the actuation of the line contactor when the mechanically connected switch is open, though allowing sufficient current to flow through the coil to maintain the contactor closed, when the mechanically connected switch is closed. The energizing coil, which is connected in parallel circuit with the accelerating resistor, is adapted to be maintained energized afterthe resistor has become short-circuited by connecting it, in circuit with a second resistor of high resistance, across the line. i I In the accompanying drawings, Figure 1 is a diagrammaticview of a control system, arranged according to my invention, for accelerating a motor. Figs. 2 and 3 are, respectively, a side and an end elevation of a preferred switch employed in connection with the system-of Fig. 1.

Referring to Fig. 1, a motor, the armature of which is shown at 1 and the shunt field'- magnet winding at 2, is connected between,

line conductors 3 and 4, separated by a line contactor 5, with an accelerating resistor 6' tact witha contact member 9. One or more contactors 10, 11 and 12 (three are. illustrated) control the shunting of successive portions 13, 14 and 15 of the accelerating resistor 6 through the medium of energizing coils 19, 20 and 21, which energization is effected by the controller arm 7 making contact with contact members '16, 17 and 18, respectively. A coil'22 is connected, at '7 9 and, 80, through the contactor 12 in its in operative position, a'protective resistor 60, the contact member9 and the controller arm 7, by way of a conductor 28, in parallel circuit with the terminals of the resistor 6. Th energizationof the coil 22, as explained below, causes the successive closing of relays 25, 26 and 27 in accordance with the strength of the current passing'through the coil 22. The coil 19 and the relay 25 are series-connected in a. circuit. extending from the line conductor3, through the point 80, by way of the conductor28, through the controller arm 7? and the contact member 16, to the line parallel relation to the coil 19 and the relay 25. The relay 26 and the contactor 10, and the relay 27 and the contactor 11, are mechanically interlocked at 55 and 56. The relay 25 engages a contact member 56, in its open position, which controls the circuit of the coil 8. This contact member may be controlled by the armature 32, as is mentioned below. A resistor 59 of high resistance is adapted to be connected across the line in circuit with the coil 8 upon the closing of the relay 25 and the consequent disengagement of the contact member-56, the contact members 56 and of the relay 25 being shunted by the resistor 59. After the resistor 6- has become short-circuited, the above-described circuit of the coil 22 is opened by the contactor 12, but this coil is maintained energized by line voltage through a resistor 61 of high resistance.

The relays 25, 26 and 27 are preferably of the type constituting thesubje'ct-matter of a copending application, Serial No. 241,259, filed June 21, 1918, by De Camp, and assigned to the YVestinghouse Electric & Manufacturing Co. The device is illustrated in Figs; 2 and 3. An insulating panel 29' carries two brackets 30 and31 for supporting the coil 22' which, when energized by the current flowing through it, creates a magnetic field for attracting an armature 32 and any desired number (three are illustrated) of additional armatures 33. A compression spring 36 is adjustably mounted upon a non-magnetizable rod 3(, slidably mounted in projections 38 and 39 which are rigidly connected to, or are integral parts of, the bracket 31. The projections 38 and 39 serve also as pole pieces for the armatures 32 and 33, respectively. A bar 40-is rigidly connected to the rod 37 and normally engages the armatures 33. The spring 36 thus normally maintains the armatures 33 in open position, with the members 41, which are carried by these armatures, in contact with the pole piece 39. The members 41 are, preferably, of non-magnetizable material to prevent freezing.

The'armature 32' is provided with brackets 42, which are pivotally mounted upon the bracket 30, and is normally retained inthe broken-line position of Fig. 2 'by a weak spring 43. The bracket 30 supports also a non-magnetizable U-shaped member 44 between the arms of which are pivotally mounted the armatures 33' which carry'the movable contact members 45,46 and 47 of the relays 25, 26 and 27, shown in Figs. 2 and 3 as closed. The stationary contact members 48, 49 and 50 of'the relays 25, 26 and 27 are mounted upon the insulating panel 29. Springs 51 are attached to lon gitudinally adjustable members 52 and to the other ends of the members 41. The pole piece 39 is provided with longitudinally adjustable members 53 to regulate air gaps between these members and the corresponding armatures. By means of this adjustment or by means of the members 52, the action of the magnetic flux produced by the coil 22 may be so regulated that the armatures 33 will be operated in the proper sequence. The contact member 45 is adapted to cotiperatewith the additional contact member 56 in the open position of the armature 33. If desired, this contact member 56 may be replaced by a contact member which is adapted to be closed by the armature 32 when this armature occupies its open position, as illustrated and described in the above referred to application by De Camp.

The operation is as follows: upon the actuation of the controller arm 7 a to the position a, the coil 8 is energized by a circuit extending from the line conductor 3, through the point 80, the conductor 28, the controller arm 7, the contact member 9, the coil 8 and the contact members 56 and 45, to the line conductor 4. The contact member 56 may be one like that illustrated in Fig. 2, or one controlled by the armature 32 in its open position. The circuit including.

the resistor 59 is not sufficiently energized to cause the closing of the contactor 5, but will maintain this contactor closed once it has become closed by the energization of the above-described circuit comprising the con tact members 45 and 56. 'Upon the closing of the contactor 5, the motor circuit is completed, current flowing through the resistor 6 and the armature 1, and also through the shunt field-magnet winding 2. Current is also shunted across the resistor 6 between the points 79 and 80 through the coil ,22. The energization of the coil 22 creates a magnetic field which attracts the armature 32 to the pole piece 38, as illustrated in the full-line position at 32. The rod 37 is thereupon pressed inwardly, in opposition to the force of the spring 36, forcing the bar 40 away from thearmatures 33. The movement'of the armature 32 is from the brokenline to the full-line position of Fig. 2. The

flux of the magnetic field will overcome the forces of the springs 51, and the armatures 33 will remain with the stops 41 in engagement with the pole piece 39. As the motor accelerates and the current begins to die down, the magnetic flux set up by the coil 22 becomes weakenedJ After a time, when the flux has decreased to a predetermined value, the spring 51, attached to the armature 33 of the relay 25, will overcome the flux of this field so that :the relay 25 will be closed. The time when this operation occurs depends upon the air gap 70 and the tension of the spring 51. The relays 26 and 27, however, will remain open. The closing of the relay 25, of course,opens the contact members 45 and. 56 but the contactor 5 remains closed because the circuitiof the coil 8 remains energized, as above de cribed, by the circuit'including theresistorfl59;

The controllerarm "7. may be actuated through positions a, and c to the position d in one step or it'ma'yl be actuated step-bystep. The description of the operation is based-upon the supposition that the controller arm Tfihas been" actuated to the position (Z in one step so as to'per'mit'gthe auto matic operation ofthe relays andgcontac tors as described below. w

Upon the closing. of the relay 25, the above-described circuit of thefjcoil 19 and the relay 25 becomesclosed through the contact member 16 and'the controller arm 7 to cause the energization of the coil 19 and the consequent closing of the contactor 10 which, in turn, creates a shunt path for the portion 13 of the resistor 6. The motor then further accelerates to decrease the voltage across the terminals of the coil 22 and thus weaken the magnetic field in the neighborhood of this coil, which permits the closing of the relay 26. A circuit is thus com pleted from the point 80, which is connected to the line conductor 3, by way of the conductor 28, through the controller arm 7, the contact member 17, the coil 20 and the relay 26, to the line conductor 4. Thecoil 20, thus becoming energized, causes theclosing of the contactor 11 and the shunting of the resistor portion 14. After the motor has further accelerated, the magnetic field surrounding the coil 22 is again weakened and the relay 27 is closed, creating a circuit for the coil 21 through the controller arm 7 a and the contact member 18. is thereupon closed to short-circuit the resistor portion 15, thereby effecting the connection of the armature 1 directly across the line.

The shunting of the resistor portion 15 by thecontactor 12 effects the opening of the circuit of the coil 22, tending to release the armature 32 and to open the relays 25, 26 and 27. I prevent this, in'thepresent system, by connecting the coil 22 across the lineconductors 3 and 4 upon the closing of the contactor 12, the circuit extending from the point 80, which is connected to the line conductor 3, through the controllerarm 7, the contact member 9, the coil 22 and the resistor 61, to the line conductor 4. The coil 22 thus remains sufficiently energized to maintain the armature 32 in the illustratcd position (Fig. 2) and, therefore, to maintain the resistor 6 short-circuited.

If the controller arm 7 be returned to the off position, causing the opening of the contactors 10, 11 and 12, and the controller arm 7 be then immediately returned to the position (Z, or if, after a failure of line voltage, energy is restored to the line, there will be danger, since the coil 22 may maintain The contactor 12 the armature 32 in the full-line, actuated position (Fig. 2 ,of causing the immediate reclo'sing of the contactors 1'0, 11 and 12, as described in my, above-mentioned copending applications, and the "consequent premature connecting of the armaturel directly across the line conductors 3 and 4 without protective resistance inseries therewith. I may prevent this undesirable effect by means of the mechanical interlocks 55 and 57 for in suring the sequential operation of the relays 25, 26 and 27' and the contact memberslO, 11 and. 12, or I may prevent this result electric ally. "In the present system, it will be noted, the coil 22 may be initially energized only when the contactor 12 occupies its open position. I

Although I have described my system as employing a particular relay device, it will be understood that other relays, and particularly those of the ordinary type, may be employed. It will be understood also that other changes may be made without departing from the spirit of my invention, the scope of which is set forth in the appended claims.

I claim as my invention:

1. The combination with an electric motor and a pair of controlling switches therefor, each of said switches having a controlling magnet coil, one of said switches being normally biased to an open position, of

means for effecting the simultaneous energization of said coils and the closing of the other of said switches only when said one switch is in its open position, and a circuit, including a resistor, controlled by said one switch for maintaining said other closed upon the closing of said one switch.

2. The combination with an electric motor having a resistor, a switch for closing the circuit of said motor and having an actuating coil, a switch for controlling said resistor and having a controlling coil in parallel circuit with said resistor and a switch mechanically connected to said controlling switch, of a pair of auxiliary resistors, means for closing the circuit of said actuating coil through said mechanically connected switchand through one of said auxiliary resistors, and means for connecting said controlling coil in circuit with said other auxiliary resistor upon the short-circuiting of said first-named resistor.

3. The combination with an electric motor having a resistor, a source of energy for said motor, a switch for connecting said motor to said source and having an actuat- &

ing coil when said one short-circuiting switch occupies said one position, means for actuating said one switch, means for maintaining said actuating coil energized, and means for energizing said parallel-connected .coil from said source.

4:. The combination with an electric motor having a resistor associated therewith, a source of energy for said motor, a switch for connecting said motor to said source and having an actuating coil, a plurality of contactors for short-circuiting said resistor, a relay for each of said contactors, means for maintaining said relays open, and a coil in parallel circuit with said resistor for overcoming said maintaining means and for maintaining said relay open, of a switch mechanically connected to the first of said relays to-close for connecting said actuating coils to said source, a circuit comprising an auxiliary resistor in parallel relation to said first relay for maintaining. said actuating coil energized at reduced voltage from said source means for successively closing said relays to cause the closing of the respective contaotors, and a circuit comprising a second auxiliary resistor for maintaining said parallel-connected coil energized at a reduced voltage from said source.

In testimony whereof I have hereunto subscribed my name this'21st day of Dec.-, 1918.

HENRY D. JAMES.

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