US1417750A - Motor-control system - Google Patents

Description

E. S. LAMMERSJR. MOTOR CONTROL SYSTEM.

APPucATloN FILEDMAY 28. 1919.

l' 1,417,750. Patented May 30,1922.

WITNESSES:

UMa/"W BY UNI-TED STATES PATENT OFFICE.

EDWIN s. LAMMEits, JR., on ELYRIA, OHIO,

.assreivo.l To wns'rinenon'sn ELECTRIC MoToRtCON'rROL SYSTEM.

specification of Letteisr'atent. 'Patented May 30, 192;;

Application filed May 28, 1919. Serial No. 300;391.

To all whom- ?zf may concern .Be it knownthat I, ylilou/1N S. Laiiiinns, J r., a' citizen of the United States, and a resident of Elyria, in the county ofLorain and State of Ohio, have invented ya new and useful Improvement in Motor-ControlSystems, of which the following' is a. specification.

My invention relates to systemsV of control for motors operable singly or in tandem, and particularly to systems involving the use of controllers Operable at predetermined speeds to effect the acceleration of the motors with which they are associated.

Systems constructed in accordance with my invention are adapted to be employed in connection with paper mills, rubber calenders and rolling mills `where the tandem op eration of motors is desirable. y

Uppn occurrence of predetermined abnormal conditions, like voltage failure or Overload, the motor becomes inoperative and cannot be again rendered operative until the controller returns to its initial position. Much valuable time may thus be lost, for the controller continues to operate at the same predetermined speed that is suitable for accelerating purposes until it returns to the initial position.

An object of my invention is to provide an accelerating system of the above-designated character, the controller of which shall return toits initial position at increased speed following the occurrence of abnormal cone ditions', so that the motor may be again started without necessarydelay.

A further object is to provide a control system for a plurality of motors whereby they may be operated singly or together in y any desired combination.

Other objects of my invention will appear in the Courseof the following description and will be specifically pointed out in the appended claims.

In the accompanying drawings, Figure 1 is a diagrammatic view of circuits and apparatus embodying my invention and F ig. 2 is aschematic viewof the circuits of the pilot motor. i

A main electric motor l, having an arma ture 2, an accelerating resistor 3 in series therewith, a series field-magnet winding 4; and a shunt ieldmagn`et winding 5, is connected by a knife switch to line conductors 7 and S. A knife switch 9 is provided for reversing the direction of current [low through the shunt held-magnet winding 5. An adjustable resistor l() and a field relay l1, having an actuating coil 12, are provided in circuit with the shunt Held-magnet 'an actuating coil`27. A push-button switch 28 is adapted to start the motor, in the manner hereinafter described, and a plurality of push- button switches 29 and 30, which may be located'in various desired positions, are adapted to stop the motor.

The main motor 1 is under the control. of a pilot `motor 31 having` an armature 32, a resistor 33 in series therewith, a resistorl` in shunt thereto and av shunt iielddnagnet winding 85. The resistors 33 and Smay be adjusted to vary the speed of the pilot motor 31, but, once adjusted, they are adapted to remain in the circuit of the pilot motor except under conditions described below. The pilot motor 3l operates, through gearing or other mechanism, a controller 135 liaving members 3G for controlling the main motor 1 and members 37 for controlling the pilot motor 31. Themembers 36 and 37 may be of any well-known drum-contact type, in which case'they may close circuits by bridging stationary contact members like those numbered 4:0, 51, i5 and 55, or they may besuitably designed cams of a cam controller The'controller lbridges contact members 40 and 45 in its off position and has a number of operativey positions Lv to 'i inclusive. A knife switch 38 is adapted to establish the control circuits for the pilot motor 31 and may occupy either of two positions, in one of which it is adapted tocone` trol the` piloty motor 31 singly and, in the other, to control it in tandem with other pilot motors in accordance with the position of a master switch 39.

Assuming that the knife switch 9 occupies its right-hand position, that the knife switches 6 and 38 occupy their upper positions, and that the controller 135 occupies its off position, a circuit niay be traced from the line conductor 8, through the knife switch 6, the coil 14;, the knife switch 9, the shunt field-magnet winding 5, contact inembers 110, which are bridged by a Ineniber 3G of the controller 135 to effect the short-circuiting of the resistor 10, the knife switch 9, the coils 12 and 15 and the knife switch 6, to the line conductor 7. The lield relay 11 is thereby closed by its coil 12 and the shunt field-magnet winding,` 5 is strongly excited. If the knife switch 9 occupies its other position, to the left, the shunt held-magnet winding 5 will be excited by current l'lowing in the opposite direction.

fissiiriiiiig,` that the controller 135 has been actuated to the position c, that the start puslrbutton switch 2S is now actuated, a circuit may be traced froni the line conductor 7, through the knife switch 38, the start push-button switch 28, the coil. 17, and contact ineinber Lll., which are bridged by the controller 259 in the position A, by a conductor 12, to a junction point 1413-5, and fifoin this junction peint 13, th rough the stop push-button switches 3() and 2l), the field relay 11, the overload relay 13 and the knife switch 38, to Ithe negative line conductor 8. The coil 1T beconies thereby energized by a circuit comprisingl the overload relay 13 to effect the closing, of the relay 1G.- Upon the closing of the lio-voltage relay 1G, a circuit is established frein the line conductor 7, through the switch 38, by a conductor l11, through a switch 16a that is mechanically connected to the relay 16, the coil 17, the contact members /11 and so on, as before traced, to the junction point 4:3, which is connected to the line conductor 8. The coil 17 is thus maintained energized by a. holding circuit eonnlirisingl the mechanically connected switch 1G, The start push-button switch 22% may now be released, A momentary ac tuation of the start push-button switch Q8 v is all that is necessary. for the relay 1G is of the sniall, quick-:diving type.

The switch l() establishes a circuit from the line coiiductor 7, through the knife switch 38, the conductor 114, the switch 16, contact members 4:5. which are bridged by a Ineinber 37, by a conductor i6 to a junction point 47'. The junction point 47 is connected to the line conductor 8 through the windings of the pilot inotor 31. The circuit of the shunt field-magnet winding 35 niay be traced from the junction point f-l through the winding; 55 and the switch 238, directly to the line conductor 8. The circuit of the armature winding' 32 extends from the junction point 47. by conductors d8, and 57, through the contact nicinber 19, by a couductor t9 through the armature 32 and the switch 35%. to the line conductor i The armature winding D0 and the ,shunt field-mag net winding lo are thus energized to ell'ect the operation olf` the pilot iiiotor il at high speed until the controller 135 actuated thereby is nioved to the lirst position (t.

A circuit is then established lroin the line conductor T, through the knife switch 238, by the conductor els-l, through the switch 16, contact inenibeis 51, which are bridged by a ineiiiber 37 in the position u by the conduetor 52, through the coil. and the contact nieinbeis 11, by the conductor vl2 to the junction point 125, which is connected to the line conductor d The, coil 22 will efl'ect the closing' of the switches 2l) and 2lA and the opening` of the switch 1), Ywhich latter e'll'ects the insertion of the resistor 33 into the armature circuit the switch effecting the linsertion into shunt with the arinature of the resistor 3l.

new circuit for the armature 32 is established frein the line eoiuluctor 7, through the switch 38, by the eoiuluctor lll, through the `switch lo, and the contact n'ienibers Ll5, by the conductors #lo and 11S, through the resistor 32%, by the conductor h), through the armature 2li), and the switch 3S, to the line conductor S. 'lhe resistor o is thereby inserted into circuit with the arnniture 32. The switch 2l establishes :i circuit which eX- teiids l'roin one side of arniature l2 through conductor Ll), :nviteh 2l, and resistor Ziel; v'to the other side of arniature 32. The resistor El thus inserted into circuit in parallel to the arniature 32. ly reason o-tthe re sisters 2323 and Piel, being` respectively connected in series with. and in shunt to, the arniatui'e Clit, the pilot inotor 3l will be actuated a t slow speed to e'lfcet the operation olf the controller 135 at a predetermined slow speed. This result is thus olitained at the instant that the contact nicinbers 51 are bridn'ed by a ineinber 37 in position ii A circuit is also established for the coil 2.7 from the conductor lf/li, which is con nected to the. lino conductor 7, through the contact n'ieinher Q0. the coil 27 and the switch it" to the line conductor 9. The switch is thereupon closed by its coil 27. The inol'or circuit 'is then established from the lino conductor 7. through the switch G, the coil 15, the contact incinber 21, the armature 1. the series field-magnet winding 4, the re-l sistor 3, the coil 141i and the switch G, to the line conductor 5%. lt will be noted that the inotor circuit is established by the switch 23. not by the controller '135, Further actuation of the controller 13o by the pilot motor 23 results in the short-circuiting' of succcr`- sire portions of the accelerating' resistor until, in the position the resistor heconues entirely short-circuitml.` ln the final position c' of the controller 13:7, the contact members 4l() are opened to effect the insertion of the resistor l0 into the circuit of the shunt fieldinagnet winding' 5, thereby bringing the inoswitch 23.

toiI up to maximum speed. In the iinalposition 2'., moreover, the circuit of thepilot. motor 31 is broken at the contact membersV tl5 so that the pilot motor 31 comes to restI when the mainmotor 1 attains its fullspeed. Itwill be noted that the contact members 40 control a portion only of the ieldresistor 10. This portion isof such value that severe' ing relays such as are commonly used. The

value of the starting torque thatis required may be varied by adjustment', as indicated by the arrow 70. For example, if the arrow is connectedbetween the points 71 and 72, the contact members 4() have no eifect. The contact members 40 are effective only when the arrow 70 is between the points 72 and 73.

In the position b of the controller 35, the

above-traced circuit of the coil 22 becomesbroken at the contact members 51. A holding" circuit is, however, iirst established, upon the closing ofthe switch 23,*from the conductor 414, which is connected to the line conductor 7, through the switch 16a, and the contact member 25, by the conductor 52, the coil 22 and the contact members 41, by the conductor 42, to the junction point43, which is connected to the lineA conductor 8.

The holding circuit 'for the coil 22 of the relay 18 is thus made through the contact members 25 ofthe switch 23. The switch 23 is usually a large contactor and islikely in service, due to dirt and other causes, to

f close very sluggishly at times. For example,

it the relay 18 formed its own holding circuit aiid the switch 23 closed very slowly, there would be danger ofthe' switch 23 taking so long toclose that the controller 135 7 would effect the short-circuiting of a large portion, i1' not the whole, of' the resistor 3, and the motor 2 subjected to a high current peak in consequence, withsubsequent damage to it and also to the circuit-breaker Thus, by placing the holding circuit for the relay 18 under the control oit' the switch 23, this is prevented, for, if

the switch 23 is not closed before the position Z) is reached, the circuit ofthe actuating coil 22 of the relay 18 will then be broken and the switch 23`cannotV then be closed until the controller 135-makes a complete revolution and the position t is again reached, when the relay 18 is once more closed and the circuit againy established to the coil 27 of the switch 23. The pilot-motor, therefore, when once started, will con-` tinue to rotate luntil the main motor 1V is actuallhT accelerated or until the stopbutton and its corresponding circuit is open.

To stop the motor7 one ot" the stop pushbuttonswitches 29 and 30 mayv be actuated to opcnthe control circuits. The circuits o1" the coils 17 and 22 of the relays 16 and y18 become thereupon opened, whereupon the circuit of the coil 27becomes broken and the'switch 23 drops open by gravity. The circuit of the pilotmotor, which was broken at the contact mem-bers 15in the iinal position of the controller 35, becomes thereupon again closed by the contact member 26,- the circuit extending from theline conductor'7, through the kniieswitch 38, by a conductor 54, through contact members 55, which are bridged by a member 37, by a conductor 5(5,fthrough a" resistor 741- of relatively high value and the contact member 26, by the conductor 57,-through the contact member 19, (the no-voltage relay 18 beingnow open) the armature 32, and the switch 38 to the line conductor 8'. The circuitof the shunt held-magnet winding 35 extends from'the switch 2G which, as just traced, is connected to the line conductor 7, bythe conductor 4:8, to the' junction point 4:7, through the shunt held-magnet winding 35 and the switch 38, to the line conductor' 8. The armature 32 is thus connected directly across the line conductors 7 and 8, free'irom the influence of the resistors 33 and 311, so that the controller 35 is actuated by the pilot motorf31 at high speed from the running position z' to the initial position a.

The resistor 711, which is employed during the operation of the controller 135 from the position z' to the off position, isthus both in series'with the eld-mag'net winding 35 and the armature 324 of the pilot motor 31.

This resistor 74 yis used merely'to'prevent becomes o cned to effect the de-enerv'ization of the coil 17 and `the consequent opening of the relays 1G and 18. The above-traced eircuits for the pilot motor 31, which do not contain the resistors 33" and 3ft, become thereupon established, since the contact members55 are bridged by the corresponding member 37 `in the positions to e ot the controller 135, andthe pilot motor 311thereupon etects'the operation of the controller 35 from whatever position it may happen to occupy, at the time, to the initial position a. The same result is attained if the stop pushbutton switch 29 or 30 is actuated when the controller 135 occupies any of its positions, and the start push-button switch 2S is actuated immediately therealter, the controller 135 proceeding thereupon to operate at high speed to accelerate the motor 1, and then returning` to the oil position. Under abnormal conditions, therefore, the controller is actuated at high speed by the pilot motor 31 to its initial position, thereby effecting` a saving,l of time in case it is desired to re-establish the main motor circuits immediately following the return of normal-circuit conditions.

It will be noted that the position i of the controller 135 is not the same as the otlf position. The two positions may, if desired, be made one, but in that event, an additional advantage accruing to the system as shown would be lost. In present commercial systems, a pair ol` switches like the switches 23, instead of only one, are employed, so that both sides of the line circuits may be opened, and diliiculties due, to grounds thereby avoided. ln the system ot my invention, a single switch only is employed without the sacrifice ot the above-reilerred-to advantage. This result is ell'ccted by advancing` the controller 135 Yfrom the running position to the oti position, in which position the main motor circuits are open at all the desired points.

According` to my invention, then, a pilot motor normally operates at a predetermined speed to effect the startingl and the acceleration ot a main motor. This is eiiected by providing, in circuit with the pilot motor, a pair olf resistors, one' in series with, and one in shunt to, the armature. Under abnormal conditions, however, the restraining` influence ot these resistors is removed and the pilot motor operates at increased speed, so as to return the controller to its initial position, in readiness 'for recommencing the operation ot the main motor.

The coi'itroller 30 is adapted to control not only the operation ot the motor 1 but ol any 'number o'lt additional motors diagrammatically illustrated at .101. 9.01, 801 and 4101, each o't which is supplied with a control system, like that 'lor controlling` the motor 1, the stop and start push-button switches only ot which are shown in the drawing.

The motors 1, 101, 201, 301 and 1101 may be controlled in any desired combination, singly or in tandem, according` to the position and the structure ot the controller For example, in the position A, not only is the motor 1 controlled as above described but also the motors 101 and 201 in tandem and the motors 301 and 1101 in tandem, that is, the push-button switches for the motor 1 are adapted to control the motor 1 as above described; the push-button switches ot either the motor 101 or the motor 201 are adapted to control both the motors 101 and 201 and the push-button switches ol' the uiotor 301 or the motor i101 are adapted lo con,- trol both the motors 301 and 401.

ln the position B ot the controller 30, the motor 1 is adapted to be controlled singly and all the other motors in tandem, that is, the push-button switches ilor the motor 1 are adapted to control that particular motor and any o't the other push-button switches are adapted to control all the remaining motors.

In position C, all the motors are controlled in tandem. ln position D, the motors 1, 101, 201 and the motors 801 and e101 are controlled in separate groups. In positio-n E, the motors 1 and 101 are adapted to be controlled singly and the remaininp` motors in tandem. ln position F, the motors 1, 101 and 201 may be controlled singly and the motors 301 and 4-01 in tandem. in the final position (il, all the motors are adapted to be separately controlled, cach by its own push-button station.

l `urthermore. ill the switch 3S oli any particular motor hapliens to he open. all Vthe motors that are controlled in tandem with the motor whose switch 3S is open will be rendered inoperative. switch 38 ot such a motor occupies its lower position, the remainii'ig motors ot the Iroup that are connected in tandem with that motor may all be operated but that motor rendered inoperative.

It is believed that this feature ot the inven tion will be made clear 'from an inspeetion otl the drawing without further description. The appended claims are designed to cover my invention in broad scope and it is desired that they be broadly construed except in so far as limitations may bc speciliv:ally imposed therein.

l claim as my invention:

1. rThe combination with an electric motor, a controller therefor and a pilot motor operable at a predetermined speed to artuatc said controller in one direction, ot means Ator automatieally elli'ecting;` the operation o'lE said motor in the opposite direction at. a seeoiul and higher predetermined speed under predetermined conditions.

2. The combination Vwith an electric motor, a source ot energy therefor, and a controller therefor having a normal position, and normally operable from said position atl a predetermined speed, ot means itor automatically returning` said controller to said position at increased speed upon failure olA power o't said source.

3. The combination with an electric motor having a resistor associated therewith, a source ot energy tor said motor. and a controller operable at a predetermined speed to eiiiect the short-circuit of said resistor, oit a motor tor actuating' said controller and means for el'ecting the operation of said .lli the push-button motor to return said controller to normal position at an increased speed upon the occurrence of abnormal conditions.

4. The combination with an electric motor, a switch for closing the circuit of said motor having an actuating coil, a relay for controlling the circuit of said coil and having an actuating coil7 and a controller for effecting the acceleration of said motor, o'fmeans for establishing the circuit of said relay coil in one position ofsaid controller and means controlled by said switch for maintaining the circuit of said relay coil closed.

5. The combination with a main motor, a controller therefor, and a pilot motor for operating said controller having armature and shunt ield-magnet windings and resistors in series with7 and in shunt to, said armature winding, of means for stopping said pilot motor when said controller occupies a predetermined position in which said main motor operates at maximum speed, a third resistor, and means for connecting said third resistor in series with said armature and shunt field-magnet windings during the operation of said controller from said predetermined position to said off position.

6. The combination with an electric motor, a controller therefor having an inoperative position and a pair of operative positions, and a switch for closing the circuit of said motor when said controller occupies the first of said operative positions, of means for actuating said controller from the other of said operative positions to said inoperative EDWIN S. LAMMERS, JR.

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