US1055907A - Starting device for alternating-current motors. - Google Patents

Description

L. A. HAWKINS. STARTING DEVICE FOR ALTERNATING CURRENT MOTORS.

APPLICATION FILED SEW, 1907.

1,055,907. Patented Mar. 11, 1913.

Fig.1 /\47; AZ 1 WiGnesses: lnvenor' Laurerice AHawkins,

' ductiontype. --This-'type of motor, as is wellcuit or both.

civi an STATES "PATEnrr. OFFICE.

LAURENCE A. HAWKINS, OF SQHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF YORK.

STABTING DEVICE FOR ALTERNATING-CUBRENT MOTORS. 7

To all la/ am ,tmy 65am.-

ing at Schenectady, county of Schenectady,

State ofNew York, have invented certain.

new and useful ,lmp rovcments'in- Starting Devices for AlternatingrCurrent Motors, of

which the following is a specification.

This invention relates to the control of alternating-current motors, and has for its object, the provision of-means. whereby mo tors of thist-ypemay be started and brought up t running speedfina reliable. and efiicient-nianne z. .2

My invention relatesmore specifically to the starting of singlephaseflmotors of the in-.

known, will-EH01}- :start fronrrest without the employment :of special starting devices, such as an auxiliary starting-winding or. a phase-- splitting device .con'nccted in the motor cir- Devices of this character-are designcdIt-o be in circuit for? only a short period during :,-;W-.hichthe motor -is beingv brought up to. synchronism; and if left in circuit. too long, .-Wlll become. overheated.

*Mea ns have. therefore been employed for changingthe connections soas to-cut outthis starting device. L

The object. of my inventionis to provide,

in connectionwith a device for changing the connections, means whe-reby'the circuitchanging switch can'rrotbe movedto running .position'until the motor has been brought up i to .the proper running speed I also provide means whereby the switch -is held in running position, and automatically returned to' the off. position upon the failu re of voltage. I

In the accompanyingdrawings,- in which- I have shown'my inventionembodied in concrete mechanism, Figure 1 is a plan view of running? T Referring; to thedrawi ng 10 is an insulatthe device showing "circuit connections, and

Figs. 2 an'd 3'showre'spectively'the circuit connections of i the motnr forl starting and ating with a series of the contact segments Specification of Letters Patent.

' Application filed September 24; 1907. Serial No. 394,278. g

base.

f j w 17, 18,19, 20, 21, 221ml 23. enact 14 Be t known .that I, Laonsncs A. Hawfums, a citizen of the United States, resid- A magnet Winding 25 of the solenoid type Patented lilar ll, 1913. v

is mounted adjacent to the. segments, as

shown, and is provided with a plunger or core 25, connected by means of a link 26 with a latch 27 pivoted to the. base at 28.

A spring 29 holds the latch in the position shown when the magnet is denergized, but

when the magnetis energized, the latch will The pin 30 on the arm 11 is as to be engaged by the shoulder 31 on the latch when, the magnet is .rcnergized,

The arrangement of circuit and mode of operation is as follows: S represents the primary windings-or stator' ot an induction motor shown with a three-phase winding Yconnection.

R is the rotor or secondaryof the motor which may be of the usual squirrel-cage type.

Two of the windings 32 and 33 are connected to the source of current through segments 22 and 23 and contact 16, conductor conductor 35, segments 17 and 18, and

contact 1 The third winding 3.6 is connected through magnet 25 to segment 20, throligh conductors 37 and-38. The resistance 39 is connected 'from segment 21 to conductor38 as shown, and the 'reactance 40 is connected to the winding 32; at 41 and to the segment 19. The resistance 39 and i the reactance 40 constitute phase-splitting devices for displacing the phase in-a well 7 known manner.

conductor 35, segment 17, contact 14, segment 18 back to line at 42'. Current will also pass through from main 42 to segment- 23, contact 16, segment 21, resistance R39, conductor 38, magnet 25, conductor 37, Wind ings 36 and 32, segments 17 and 18, back to line; also from main 42 to segment 22, thence through windings 33 and 36, magnet- 25, segment 20, segment 19, react-ance 40 and back to line, through segments 17 and 18. This gives the motor the necessary starting torque, which, therefore, starts to rotate. As soon as the magnet is energized, the latch 27 is moved into the path of the pin 30, so that the arm or lever cannot be moved out of contact with the segments. As the motor begins to speed up, the energy of the magnet 25 begins to decrease. -The decrease in th'e flow ofcurrent through this magnet as the motor speeds up is due to the following cause: it. is a well known fact that a singlephase induction motor at starting has a simple, pulsating, unidirectional field due to the single-phase current supplied thereto,

while when the motor is up to speed, a rotary field exists. In other words, the rota tion of a secondary member causes a crossmagnetization which induces in the motor windings an electromotive force in quad rature with the impressed. electromotive force. Consequently, in the arrangement shown in Fig. 2, the magnet winding 25 at starting has impressed upon it a voltage due" only to the phase-splitting devices. As the motor speeds up the cross-magnetization rises and induces an electromotive force in the primary Winding of the motor in quadrature to the impressed electromotive force and counter to the electromotive force of the phase-splitting devices. Consequently, as this counter-elect romotive force increases,

the current through the magnet winding 25 falls, and when the motor is broughtup to running speed, the energy of the magnet is practically zero and the spring 29 therefore draws the latch 27 out. of the pathof the pin 30, so that the arm 11 may be moved into running position. \Vhen this position is reached, the contact 15 bridges segment 20 and cont-act stud 24, the contact 15 passes off segment 19, and the contact 14 still.

bridges segments 17 and 18. Contact. 15 in passing off the segment 19 opens the circuit of the reactance 40 and the circuit of wind ing 33 and resistance 39 is broken by the passing of the contact 16 off segments 21 and 22. The circuits will then be as shown in Fig. 8, the magnet 25 being energized as' follows: from main 42 and segn'ient 23, to contact stud 24, segment 20, conductor 38, magnet 25, conductor 37, windings 36 and 32, segments 17 and 18, and back to line. The magnet thus being in series with the main motor windings is again energized and draws the latch 27 down so that the sbonider 31 engages the pin 30 and holds the arm ii in running position. Upon failure of voltage the magnet 25 will be decnergized and the arm 11 will be retinrn'ed to the off position in the usual manner.

It will be seen that I have provided a simple and efficient device for bringing the motor up to running speed without danger to the motor and also for placing the motor in a protective position upon the failure of voltage. 4

Various modifications .of my invention will, of course, suggest themselves to those skilled in the art,without departing from the spirit of my:- invention, the scope of which is set forth in the annexed claims.

What I claim as new,'and desire to secure by Letters Patent'of the United States, is,

1. The combination with an alternatingcurrent 'motor having different connections of the windings for starting and running, of a switch biased to the 01f position for changing said connections, andla magnet winding connected to be energized in quadrature to the main motor windings for limiting the operation of-said switc 7 2. The combination with an alternating current motor having different connections of the windings for starting and running, of a switch biased to the off position for changing said connections, a magnet winding connected tov be decreasingly energized during starting, means'whereby the magnet is connected in series withthe motor during running, and means controlled by the magnet? for holdingthe switch in the running position.

3. The combination with an alternating current motor having different connections of the windings for starting and running, of a switch biased to the off position for changing said connections, a magnet winding connected in the. motor circuit, and means controlled thereby for preventing the movement of the switch to running position until the motor reaches a predetermined speed.

4. The combination with an alternatingcurrent motor having different connections of the windings for starting and running, of a switch biased to the off position for changing said connections, a magnet-winding connected in the motor circuit, and means con- .trolled thereby for preventing the move venting the movement of the switch to running position until the motor reaches a predetermined speed, and means whereby the and means controlled thereby for preventing the movement of the switch to running position until the motor reaches a predetermined speed.

7. The combination with an alternating current motor having difi'erent connections of the windin for starting and twinning of a switch biased to the oil position for changing said connections, a ma gnet winding for limitin the movement of said switch and means w ereby when the switch is moved to starting position the magnet is decreasingly energized 'dnring starting and when the switch is moved to running position it is energized in series with the motor. 8. 'The combination with an alternating current motor having dint-rent connections of the windings for starting and running, of a switch biased to off position for changing said eonnections,a magnet winding connected to be decreasingly energized duringstarting, means for connecting said magnet in series with the motor durifig running, and means'controiied by said magnet for pre ventingthe movement of the switch to run- .ning position until the motor reaches a predetermined 5 rd and then locking said switch in running position.

9. The Combination with a SlHQlWplHML induction motor and phase-splitting devices for starting said motor, of a switch biased to the off position and arranged to cut said devices out of circuit, a magnet winding connected in circuit with the motor, and means controlled thereby for preventing the movefor starting saidmotor, 0

ment of the switch to running position when the magnet is energized and for holding the switch in running position when running conditions are established.

10. The combination with a single-phase induction motor and phases litting devices i a switch arranged to out said devices out of circuit, a magnet connected .to be energized in quadrature to the main motor windings, and means controlled by said magnet for preventing movement of the switch to running position while the magnet is energized.

..11. The combination with an alternating current motor having different connections of windings for starting and running, of a -switch;,tharefor havinga starting position between the off and therunning position an I biased to the of! POSltIOI], magnet windings connected to be energized in quadrature to the main motor winding, and a latch controlled by said magnet and arranged to prevent movement of the switch to running position under Pl'ttlOlPl'llllllPtl conditions .of the motor circuit.

12. The combination with a single phase induction motor. a phase-splitting device for starting thesame, of a switch arranged to out said device out of circuit a magnet connected so as: to have impressed upon it an electromotive force due to the phase-split ting device during starting and connected in series with the motor during running. and means for preventing the movement of the switch to running position until the motor reaches a predetermined speed and then locking the switch in running position.

13. The combination with a single-phase induction motor and phase splitting device for starting the same, of a switch biased to the oil position and arranged to cut said device out of circuit, a magnet winding connected to be energized in quadrature to the main inotor windings when the switch is in a starting position, connections whereby said magnet is reds gized when the switch is moved to running position, a device controlled by said magnet. for preventing the movement of the switch to running position until the magnet is deenergized and for lot-king the switch in running position when the magnet "ei nergized.

14. The en nation with an alternating current motor of a starting switch therefor biased to off position, a magnet winding for controlling said switch connected so as to be derreasingly energized during starting and means for connecting said magnet in series with the motor during running.

15. A starting device for electric motors comprising a switch biased to oil position, a

magniet winding having difierent connections" in the motor circuit r startin and running, and means controlled there y for preventing the movement of the switch to running position until the motor reaches a predetermined speed, then holding the switch in running position.

. 16. A starting device for electric motors comprising a switch, biased to off position a magnet winding connected in the motor circuit so as to be decreasingly energized during starting of the motor, means whereby said magnet is caused to be energized uniforml during running, and a latch controlled by said magnet for preventing the movement of the switch to running position until the motor reaches a predetermined speed and then holding the switch in running position.

17. A starting device for electric motors comprising a switch havin a starting posh tion between the off and t e running posi means for preventing the movement of the switch to running position until the motor reaches a predetermined speed, and then holding the switch in running position.

181A starting device for electric motors comprising a switch having a starting position between the off and the running position and biased to the off position, a magnet winding connected to be decreasingly energized during starting, means whereby said magnet is caused to be energized uniformly during running, and lnea-ns controlled by said magnet for preventing the movement of the switch 'to running position until the motor reaches a predetermined speed and for holding the switch in running position.

19. The combination with an electric niotor, of a starting device therefor comprising :1 switch biased to the 011' position, a magnet Winding having dilterent connections in the motor circuit during starting and running, and means controlled thereby for preventing the movement of the switch to running position until the motor reaches a predetermined speed, and then holding the switch in run ning position.

In witness whereof, I have hereunto set my hand this 23rd day of September, 1907.

LAURENCE A. llAlYKlNri.

Witnesses BENJAMIN B. HULL, l'leucx Oicronn.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner or Patenh,

Washington, D. 0.

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