US1930950A - Motor control apparatus - Google Patents

Description

Oct. 17, 1933. c w DALZELL v 1,930,950

MOTOR CONTROL APPARATUS Filed July 20, 1931 BH J g-j Ii 7 15 -fir-CH BHJ c iQ C CHJJ i 2 INVENTOR.

C,W. Dar/22,

Patented Oct. 17, 1933 breaker actuated by the motor controlling con-1 MoToR CONTROL APPARATUS Clarence W. Dalzell, Swissvale, Pa., assignor to The Union Switch & Signal Compamuswiss vale, Pa acorporation of Pennsylvania ]inp li0ation July 20, 1931. Serial No.'551,S59- rema ns. (c1. 175 294) .My invention relates to motor control apparatus, and particularly to apparatus'lforv controlling a railway switch operating motor from a distant point suchas an interlocking tower or despatchers cabin. I a 1 1 One object-of my invention is to decrease the amount of power which it'is necessary to transmit from thecontrol location to the motor controlling contactor, and I accomplish thisresult by eliminating the usual form of overload circuit tactor and by substituting therefor a thermal overload-relay cooperating with'a locallyenergized controlling magnet applied to the motor circuit in a novel manner. a i

. Another object of-my invention is'to provide a thermal overload relay capable of being reset electrically after a very short cooling time.

A further object is to provide a flexible and reliable motor control andoperating circuit for the safe and eiiicient operation of an outlying railwayswitch.

' -I will describe'one form of 'apparatus embodying my. invention, and will then novel features thereof in claims.

point out the The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

here shown comprises an armature 1 and a field 2. Operatively connected withthe switch A is a cut-out controller D comprising an arm 3 and contact segments 4 and 5. Contact 3-4 is closed at all ltimes except when the switch occupies its extreme normal position, and .contact 3-5 is closed-at all times except when the switch occupies its extreme :reverse position.

' The motor M is controlled by a polarized motor controller? which in turn is controlled by a manually operable pole-changer Lusually located at a point remote'from the controller P. .The

tacts on a manually operable switch lever.

Polarized controller P comprises an armature 9; pivoted upon a pin 10 mounted in the polarized core 11 and capable of being attracted to either one or the other of neutral cores 12 or 13 depending upon the polarity of the currentflowing in the series windings 14 and 15 as determinedby the position of pole-changer L, provided polarizing winding 53 on core 11 is energized at the same time. .Armature 9 of controller? operates contact arms'6 and 7 which act to close .contacts which will be explained hereinafter.

pole-changerL mayconsistof pole-changing con- 6-16 and 7-17 when the armature assumes the position shown in the drawing, and to close contacts 6-18 and 7-19 when the armature is reversed. Contact arms 6 and 7 serve asameans for reversing the direction of current flow through the armature 1 of motor M without influencing.

the direction of current now through the field Winding 2. The position of armature -9 determines therefore whether normal or reverse rota-j tion of motor M will follow,resulting in switch A assuming its corresponding normal or reverse position. yv i Armature 9 also operates contact arm 8 to close contacts 8-20 or 8-21 which permit relay E to become energized. Relay E provides'a means for resetting thermaloverload relay T; and opcrates contact fingers -22 and23,-the purpose of Relay E comprises a winding 27 capable-of attracting an armature 28 pivoted at'29. 'A pin 30 provides a stopfor armature 28 when winding 27' iS-de energized. r

Thermal overload relay T'comprises two bimetallic strips-31 and 32 fastened to a supporting block 33 and joined'together at their free ends byja link 34. The-bimetallic strips 31'and32 are so disposed with respect to each other that a U i change in ambient temperature will cause said 1 Referring to the drawing, the reference char-- acter A designates a railway switch which is actu-' ated by'an electric motor M which in the formstrips to tend todeiiect in opposite directions; with the result that no'appreciable movementof roller 35Vattachedto strip 31 occurs until. winding 36 becomes heated. Compensation for'ambient temperature is obtained in this'manner; I

causes .armature 23 tolift arm 37 through'the medium of slotted link '41. a

Magnet F comprises two windings 42 and 43} wound in opposition to each other and connected in series acrossthe motor armature. The circuit for windings 42 and 43 is so arranged that when contact 38-39 of thermal-overload relay T is closed, these windings are in parallel with each other and the current now througheach winding is in'such direction that the resultant fluxes-and,-

causing'magnet F to pickup, opening contact 44-45 and closing contact 46-47. When, however, contact 38-39 becomesopened for anyreason, current flows in series through windings 42 and 43 so that the fluxes oppose each other and magnet F releases, opening contact 46-47 and closing contact 44-45.

In order to explain the operation of the apparatus as a whole, I shall assume that the operator wishes to reverse switch A from the normal position shown in the drawing. To do this, he reverses pole-changer L, establishing a circuit for relay E from one terminal BH of the source, arm 48 of pole-changer L, wire 50, wire 51, con tact 8-20, wire 52, and winding 27 of relay E to the other terminal CH of the source. Relay E now becomes energized, opening contact 22-24 and closing contacts 22-25 and 23-26. The closing of contact 22-25 establishes a circuit for polarizing winding 53 of controller P, starting at terminal BH, winding 53, wire 54, and contact 22-25 to the other terminal CH of the source. Contact 23-26 closes a circuit for windings l4 and 15 of controller P which can be traced from terminal BH, arm 48 of pole-changer L, wire 50, wire 55, contact 44-45 of magnet F, wire 56, contact 23-26 of relay E, wire 57, windings 15 and 14 of controller P, wire 58, wire 59, and arm 4 9 of pole-changer L to the other terminal CH of the source.

With the windings of controller P energized as above, armature 9 becomes attracted to core 13 and contact fingers 6, 7 and 3 become reversed from the position shown in the drawing. The opening of contact 8-20 causes relay E to release, and the closing of contact 8-21 short circuits relay E and prepares an energizing circuit for relay E effective upon subsequent reversal of pole-changer L. The release of relay E opens contacts 22-25 and 23-26 so that all windings on controller 1? become deenergized. The closing of contacts 6-18 and 7-19 energizes windings .42 and 43 of magnet F in parallel, the circuit for winding 43 starting at terminal BH, contact 3 5 of controller D, wire 60, contact 6-18, wire 61, wire 62, winding 43 of magnet F, wire 63, wire 64, flexible connector 65, contact 88-39 of relay T, wire 66, and contact 22-24 of relay E to the other terminal CH of the source. The circuit for winding 42 is the same as above except that at wire 61 it branches to include wire 67, armature l of motor M, wirev 68, wire 69, winding 42, wire 70, and thence through wire 64 over the same circuit just traced for winding 43. It will be noted that under this condition winding 42 aids winding 43 and the energy in winding 42 is nearly as great as in winding 43, being decreased only by the po 'tential drop across the armature 1 of motor M at standstill.

It will be apparent therefore that the combined effect of windings 42 and 43 creates a strong pick-up impulse in magnet F, closing contact 46-47 and opening contact 44-45.

When contact 46-47 is closed, a circuit for motor M is established which can be traced from terminal BH, contact 3-5 of controller D, wire 60, contact 6-18, wire 61, wire 67, armature 1, wire 68, wire 71, contact 7-19, wire 72, wire 73,

held 2, wire 74, contact 46-47, wire 75, heatinsure that should lever L be reversed with magnet F energized and motor M operating, contact 46-47 will become opened due to the establishment of the series connection for windings 42 and 43 of magnet F by the opening of contact 22-24 of relay E, with the result that contact 46-47 will cut off motor current before contact 44-45 closes to energize windings 14 and 15 of controller P for a reversal of contacts 6 and 7, otherwise contacts 7-19 and 6-18 would be required to break the motor current, for which service they have not been designed. When switch A reaches its extreme reverse position, contact 3-5 of controller D opens, deencrgizing motor M and magnet All parts will then be deenergized.

Should the operator wish to restore switch A to the normal position shown in the drawing, he will restore pole-changer L to the position illustrated, whereupon the following sequence of operations, already described in connection with the movement of switch A from normal to reverse will take place: Relay E will be energized, energizing controller P which will restore contact arms 6, 7 and 8 to the position illustrated, resulting in deenergization of relay E which in turn causes magnet F to become energized, deenergizing, controller P and energizing motor M. The operating circuit for motor M can now be traced from one terminal 13H, contact 3-4 of controller D, wire 77, contact 7-17, wire 71, wire 68, armature 1, wire 67, wire 61, contact 6-16, wire 78, wire 73, field 2, wire 74, contact 46-47, wire 75, heating winding 36, and wire 76 to the other terminal CH of the source. It will be noted that the direction of current flow through the motor armature has now been reversed, the flow through the field Winding remaining in the same direction as before, with the result that motor M will reverse its direction of rotation and will restore switch A to the normal position in which it is shown. As soon as switch A reaches its normal position, contact 3-4 of controller D will open, deenergizing motor M and magnet F. All parts will then be restored to the positions in which they are illustrated.

Contacts 22-25 and 23-26 of relay E are necessary in order that controller P may remain deenergized at all times except during the short interval required for reversing contact arms 6, 7 and 8. Contact 22-24 of relay E is provided for the purpose of releasing magnet F should polechanger L be reversed while the motor is operating. In this manner, contact 22-24 is instrumental in allowing full control over the motor M to be maintained by pole-changer L during any part of the stroke of switch A, i. e. switch A can be brought back to its initial position after completing any part of its stroke by a reversal of pole-changer L. The sequence in which the elements operate to bring about a reversal of switch A in mid-stroke is the following: Reversal of polechangcr L, pick-up of relay E, release of magnet F, reversal of controller P, release of relay E, and finally pick up of magnet F which energizes the motor to operate switch A.

To explain the operation of the apparatus when motor M becomes overloaded, caused for example by an obstruction in switch A, I shall assume that motor M is operating to reverse switch A from the normal position shown in the drawing when such an obstruction occurs. The current taken by motor M will now increase and the heat developed in winding 36 of relay T will cause bimetallic strip 31 to deflect to theright. Roller 35 will disengage arm 37 causing contact 38-39 to. open,

I 1,930,050 breaking the'paiallel connection for" windings 42 and 43 of magnetF and forcing the'current to fiow through both of these windings in series, whereby opposing fluxes are created and magnet Freleases.

i The release of magnet'F .opens'contact 46-47 pole-changer L to the position shown in the drawing, whereupon relay E will become energized and will reset contact 38-39 which will now remain closedafter relay E is subsequently deenergized because of the engagement of roller 35 with arm 37.

I The above reversal of pole-changer L will cause the switch A to be movedaway from the obstruction so that a second trial to move the switch against theobstruction may be attempted. Y

The design of relay T and particularly the positioning of roller 35 with respect to arm 37 issuch that-an appreciable time interval is required I for operation of relay T in the presence of an overload, but the relay will restore itself in a very short interval which is only a fraction of the time required for operation. This result is obtained because roller 35 must travel a substantial distance before arm 37 will be released but a small return movement of roller 35is suflicient for latching arm 37 against roller 35.

vIt will be apparent, therefore, that the time which the operator must/wait beforereversing pole-changer L after an overload has occurred is very short and is therefore not objectionable from a practical operating standpoint. i While I have illustrated motor control apparatus embodying my invention as applied to the control of a motor for'operating a railway switch, it will be readily understood that'apparatus embodying my invention is not limited to this use, but may be applied to the control ofany motor for operating any movable device- Although I have .herein shown and described only one form of motor. control apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims invention.

Havingthus described my invention, what I claim is: p p g 1 1. In combinatiom an electro-responsive device, a circuit for energizing said device including a normally closed'contact, two windings for without departing iromthe spirit and scope of my governing said contact, means responsive to the magnitude of the current received by said device,

and a governingcircuit forrsaid. windings controlled by said means in such manner that said windings aid one another when said current is ,below'a predetermined value whereby saidcon-iv tact remains closed butthat said windingsoppose one another when said current exceedsa predetermined value whereby said contact becomes opened.

2.In combination, an electro-respons'ive deviceftwowindings, means for causing said deand for energizing said windings in series when said device receives current exceeding a'prede termined value.

3; In combination, an electro-responsive device, a magnet comprising two windings capable of assuming one or another of two conditions according as said windings are energized in parallel or in series with each other, means for controlling said device in accordance with the condi-,

tion of said magnet, and means responsive to the magnitude of the current supplied to said device for energizing said windings in parallel or in series according as said current is below or above a w predetermined value.

4. In combination, an electro-responsive device, a controller comprising a magnetizable core in which a plurality of fluxes can be established in such manner as to aid or oppose each other, means for governing said device according as said fluxes are aiding or opposing, and means including a plurality of windings on said controller for establishing aiding or opposing fiuxesin said core according as the current received by said device is below or above a predetermined value.

5. Incombination, an electric motor comprising an armature, a first and a second winding connected in series across said armature, means for supplying current to said armature in accordance with one or another of two conditions effective when said first and second windings receive current in parallel or in series with each other, respectively, and means responsive to the magnitude of the current supplied to said armature for causing said first and second windings to receive currentin parallel with each other if said armature current is below a predetermined value and for causing said firstand second windings to re ceive current in series with eachother if said armature current exceeds a predetermined value. 6. In combination, a movable device,,an electric motor for operating said device, two windings capable of assuming one or another of two conlel or in series with each other according as the motion of said movable device is freeor obstruct ed, and means for governing said motor inaccordance with the condition of said windings- 7. In combination, an electro-responsive device, a circuit for energizing said device includinga normally closed contact, two windings for governing said contact, means responsive to-the magnitude of the current supplied'to said device for causing the fluxes set up by said two windings to substantially neutralize one another if saidcurrent exceeds a normal value, and means for causing said contact to-open when said fiuxes are substantially neutralized.

CLARENCE W. DALZELL.

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