US733550A - Controlling device for alternating-current motors. - Google Patents

Description

No. 733,550. PATBNTED JULY 14," 1903.. D. L. LINDQUIST.

CONTROLLING DEVICE FOR ALTERNATINO OURRENT MOTORS.

APPLIOATION FILED MAR. 25. 1903. N0 MODEL. 4 SHEETS-SHEET 1. 1

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WITNESSES: INVENTOR J 4/ 0 @md fiwu f aMy/Z ATTORNEY T S I U 0 D N I L L D CONTROLLING DEVICE FOR ALTERNATING CURRENT MOTORS.

APPLIUATION FILED MAR. 25, 1903.

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INVENTOR ATTORNEY No. 733,550. PATENTED JULY 14, 1903..

- 1). L. LINDQUIST.

CONTROLLING DEVICE FOR ALTERNATING CURRENT MOTORS.

APPLICATION FILED MA1L25. 1903.

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PATENTED JULY'M, i903..

D. L. LINDQUI ST. CONTROLLING DEVICE FOR ALTERNATI'N-G CURRENT MOTORS.-

APP'BIOATION FILED MAR. 26- 1903.

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ATTORNEY UNITED STATES I Patented July 14, 1903.

PATENT OFFICE.

DAVID L. LINDQUIST, OF YONKERS, NEW YORK.

SPECIFICATION forming part of Letters Patent N 0. 733,550, dated July 14, 1903.

Application filed March 25, 1903. Serial No. 149,501. (No model.)

To all whom it may concern.-

Be it known that I, DAVID L. LINDoUIs'r, of Yonkers, VVestchester county, New York, have invented a new and useful Improvement in Controlling Devices for Alternating-Current Motors, of which the following is a specification.

The invention consists in a controlling device for alternating-current motors of the induction type, whereby the motor is enabled directly to control itself without the aid of any extraneous appliances. This I accomplish by the change of voltage in the secondary circuit of the motor from the period of start up to the attainment of full running speed, the said volt-age then decreasing from a maximum to substantially zero. This principle is wholly new in the artand the result set forth has never before been achieved.

My invention consists, further, in an apparatus, hereinafter disclosed, which is one embodiment of my principle. It is to be understood that I do not limit myself to this particular apparatus, but intend to embrace in my claims the widest range of equivalents which a pioneer invention of the present type may include, and therefore I desire that my claims may be construed broadly.

My apparatus consists more particularly in a plurality of electromagnets each having two energizingcoils. One set of coils is first energized from the primary source of currentsupply, whereby their magnets are caused to cut resistances into the secondary circuit of an alternating-current motor. The current may be polyphase. After the magnets have thus operated current is directed into the primary of said motor. The secondary of the motor and the second set of coils are then energized, but at approximately the same instant the first set of magnet-coils are deenergized, leaving the resistances retained in circuit by the magnetizing effect of the second set of coils. The voltage induced in the mo tor secondary will be greatest when said secondary is stationary and becomes reduced as said secondary speeds up. The magnets are constructed of different strengths, so that as soon as the voltage in the secondary falls to a certain point one magnet will operate to cut a fraction of the resistances out of the motor-circuit. The motor will then run at augmented speed, and the voltage will again fall until the second magnet in turn and in like manner operates, and this will continue until all the magnets have acted to cut out all of the resistances, at which time the motor will have attained full running speed. The voltage in the second set of magnet-coils will then be approximately zero, and hence after the motor has attained its running speed no current will exist in the controlling magnets and all waste of energy which otherwise might take place by reason-of a constantly-maintained current will be avoided.

The manual control of the apparatus after current from the main line is admitted to the usual converter is confined to the movement of a single circuit-closing lever, which first establishes circuit in the first set of magnetcoils, then also in the motor and second set of coils, and then breaks circuit in said first coils.

In the accompanying drawings, Figure l is an electrical diagram showing my apparatus applied to the control of a three-phase alternatingcurrent motor. Fig. 2 illustrates in perspective one of the controlling-magnets in this system. Fig. 3 is an electrical diagram also showing the application of my apparatus to a three-phase system, but with athreephase transformer, with the controlling-magnet coils connected in series and with a modified arrangement of safety-wires. Fig. 4 is an electrical diagram showing the application of my apparatus to a two-phase system. Fig. 5 illustrates in perspective one of the controlling-magnets in this system. Fig. 6 is an electrical diagram showing the application of my apparatus to a single-phase system. Fig. 7 shows in perspective one of the controlling-magnets in this system.

Similar numbers and letters of reference indicate like parts.

Referringfirst to Fig. 1, a b c are the conductors of a three-phase current, which when the switch cl is closed energizes the converter e. The secondary terminals of the converter are connected to the triple switch f, the lovers of which when moved simultaneously by their actuating-handle are adapted to make contact, first, with the terminals 'nals45 6.

1 2 3 only, then with the terminals. 1 and 4, 2 and 5, and 3 and 6, and, finally, with the terminals 4 5 6 only.

At g.h i are three electromagnets, one of which is shown in perspective in Fig. 2. The core A of each magnet is cylindrical, having end projections B. Around each core is wound, drum fashion, three coils, the turns lying between the projections, as shown. The three coils of each groupj 7; l are connected instar. Their outer terminals are connected, respectively, to the switch-terminals 1 2 3. The switch-terminals 4 5 6 connect with the star-connected primary coils of a three-phase induction-motor. The zero-points 10 of each groupj is Z of Wires connect, respectively, to the zero-point 8 of a group of induction-coils n, to the outer terminals of which group the main primary wires respectively connect.

The secondary coils of the motor connect by wires 11 12 13 with the star-connected resistances P Q R and also by branch wires let 15 16 with the terminals ofthree groups 3 t u of star-connected coils, also wound on magnets g h i. In said branch wires are resistances v. C D E respectively represent the movable circuit-closingarmatures of the magnets g h 1'. Each armature when not attracted by its magnet makes contact with a grovp, as y, of three fixed terminals. The terminals inv the path of armature O connectdirectly with the wires 11 12 13. The terminals in the paths of armatures D and E connect with the resistances P Q R at points hereinafter noted. The zero-terminal of resistances P Q R connects by wire 17 with the zero-terminals of the groups 3 2, u of magnet-coils.

The operation of the device is as follows: Switch d being closed, switchfis caused to close contact with the terminals 1 2 3. Circuit is thus established to the coilsj is Z of magnets g h t', energizing said magnets,which attract their armatures O D E and so break circuitat w m y. The movement of switchf continuing, circuit is also closed through the terminals 4 5 6 to the primary coils m of the motor. The motor-armature then being at rest, the voltage induced thereon is at a maximum until revolution of the armature begins. The resistances P Q B being in series with the secondary coils 0, the starting-current is kept down so as to give to the motor the necessary starting torque. The magnet-coils s t 11. now receive voltage proportional to that existing in the secondary coils of the motor, and therefore both groups of coilsj Z and s t u on the magnets g hi are energized and hold up the armatures O D E. The further movement of switchf finally breaks circuit at terminals 1 2 3, leaving it closed at termi- Although coilsj k Z on magnets g hiare thus cut out, coils s in remain charged, and hence said magnets continue to hold their armatures O D E. All of the starting resistance P Q R is now in the motor secondary circuit. As the motor starts and its speed increases, the voltage in the secondary drops proportionately to said speed, or, in other words, to the slip of the secondary. Returning now to the groups 8 t u of magnetcoils, it is important to note that each magnet energized thereby is of different strength from its associates. This may be effected in any suitable way, as by a variation in the turns of wire forming the coils of each group or by varying the air-gap between magnet and armature, or by both means. The motor now reaches a speed beyond which it cannot go with the whole resistance P Q R in circuit, and by reason of this increase its voltage has decreased. One of the magnetssay magnet 'is to be made of such strength as that when the aforesaid reduction in voltage occurs its group of coils to, which alone is sustaining its armature E, becomes no longer capable of so doing. Armature E then closes contact with itsrassociated fixed terminals (1 and these terminals are connected to the resistances P Q R at the points 10 q r, so as to short-circuit a certain portion of each resistance. The motor speed now increases still further and the voltage in the secondary circuit decreases until the magnet next in strength--say magnet h-in like manner releases its armature D, the terminals wof which are connected to the resistances P Q R at points 19 q" r, so that an additional portion of each resistance thus becomes short circuited. Theresultingincreaseofspeedcauses the last magnet g to operate in the same way, when all of the resistances P Q R will be short-circuited. The motor now runs at full speed, no appreciable current flowing through the coils of magnets g h 2', because the external secondary voltage is zero.

The group n of induction-coils connected to the main primary wires gives a zero-point at 8, which, as already explained, is connected to the zero-point 10 of the magnet-coilsjk Z. This is a safety device designed for use in case one or more of the contacts for closing circuit through the magnet-coilsj 7c- Z should become impaired,iu which event circuit would still be established back through the zeropoint so long as one branch of said coils remained operative.

The circuit-resistances o in the secondary circuit serve to insure sufficient resistance in the coils s t u. The wire connecting the zeropoints of said coils with the zero'poin ts of the resistances P Q R is a safety device, which guards against the effects of impairment of one or more of said coils stu. The coils j kl are preferably to be of greater magnetizing strength than the coils s t u in order to prevent dropping of the armatures O D E in case the secondary of the motor should assume a position to cause the group of coils j 70 Z and s t u to polarize the magnets in relatively opposite'directions.

As is well known, alternating currents may be of dilferent numbers of phases, and therefore apparatus such as the foregoing is necessarily modified to adapt it to the particular IOC IIO

I a single-phase current.

phase-current employed. In the foregoing description I have shown its application to the type of current in most common usethree-phase-when two transformers are employed and all the operating-magnet coils are connected in parallel and a primary zeropoint obtained from the three induction-coils, which are connected for safety to the zeropoints of the magnet-cores g h t. the adaptation is still to the three-phase current; but here I employ a three-phase starconnected transformer F and carry the safetywire for the magnet-coilsj is Z to the zero-point of its secondary F. The magnet-coils s to are here shown as connected in series.

In Fig. 4: the device is applied to a twophase current. A two-phase transformer G is connected with a three-wire system, the motor having a two-phase primary E and a three-phase secondary I. The coils of magnets g 71. 2', one of which is shown in Fig. 5, may be wound as shown for two-phase current. The third wire here acts as a safety device in case one branch of the operating circuit becomes impaired.

Fig. 6 illustrates the apparatus applied to Here a single-phase transformer J supplies current to a singlephase motor K. The primary L of the motor is split into two-phase, with a resistance M in one phase in order to get a phase difference on starting, this being merely one way of accomplishing the purpose. The non-inductive resistance M is in series with the coil X, and said resistance and coil X are, respectively, parallel with the coils y z. The secondary N is three-phase, with a resistance P Q R connected in the same manner as for three or two phase currents. The magnet winding is shown in Fig. 7.

I claim- 1. In combination with an alternating-current motor of the induction type, means for controlling said motor, said means being itself controlled by the change in voltage in the secondary of said motor.

2. In a controlling device for alternatingcurrent motors, means for varying resistance in the secondary motor-circuit controlled by the voltage in said secondary.

3. In a controlling device foralternatingcurrent motors, means for decreasing resistance in the secondary motor-circuit controlled by decreasing voltage in said secondary.

4. In a controlling device for alternatingcurrent motors, means actuated by the primary motor-circuit to interpose resistance in the secondary circuit of said motor and means for gradually cutting out said resistance controlled by the change in voltage in the secondary motor-circuit.

5. In a controlling device for alternatingcurrent motors, electromagnetic means constructed and arranged, first to interpose resistance in the secondary circuit of said. motor and means for then establishing current in the primary thereof.

In Fig. 3

6. In combination with an alternating'current motor of the induction type, an electromagnetic controlling device therefor constructed and arranged to be actuated bythe voltage in the secondary of said motor during the period from the starting of the motor to the attainment of predetermined running speed. I

7. In combination with an alternating-current motor, an electromagnetic controlling device disposed in the secondary circuit thereof; the said device being constructed and arranged to be energized and active from the period of starting of the motor up to the attainment of predetermined running speed and thereupon to become tleenergized and inactive.

8. In combination with an alternating motor of the induction type, an electromagnetic device and a variable resistance in the secondary motor-circuit controlled thereby, the said device being actuated by said motor, after said motor has started and reached a given speed, to reduce said resistance up to the attainment of a predetermined running speed.

9. In combination with an alternating-current motor of the induction type, means for cutting resistances into the secondary circuit of said motor and means controlled by the voltage in said secondary circuit for gradually cutting out said resistances until full running speed is reached.

10. In a controlling device for alternating current motors, an electromagnet energized from the secondary of said motor, and a variable resistance controlled by said electromagnet and in circuit with said secondary.

11. In a controlling device for alternatingcurrent motors, an electromagnet energized from the secondary of said motor, and a variable resistance controlled by said electromagnet and in circuit with said secondary; the aforesaid parts being constructed and arranged so that when said motor shall have attained a predetermined speed said magnet shall operate to out said resistance out of circuit.

12. In a controlling device for alternatingcurrent motors, a plurality of electromagnets energized from the secondary of said motor and resistances respectively controlled by said magnets and in circuit with said secondary; the aforesaid parts being constructed and arranged so that upon the motor attaining certain predetermined speeds said magnets shall successively operate to out said resistances successively out of circuit.

13. In combination with an alternating-current motor of the induction type, a plurality of electromagnets, a plurality of circuit-closers controlled by said magnets, a plurality of resistances controlled by said circuit-closers, means for opening said circuit-closers and thereby cutting all of said resistances into the secondary circuit of said motor and means controlled bysaid motor for causing said circuit-closers successively to short-circuit said resistances until full running speed of said motor is reached.

14, In a controlling device for alternatingcurrent motors, a controlling-electromagnet having a coil energized from the primary source of current and a coil energized from the secondary of said motor.

15. In a controlling device for alternatingcurrent motors, a controlling-magnet having a coil energized from the primary source of current and a coil energized from the secondary of said motor, the first-named coil being constructed to have a greater energizing strength than the second coil.

16. In a controlling device for alternatingcurrent motors, a controlling-magnet having a plurality of coils, means for energizing one coil or a number less than all of said coils from the source of currentsupply to the primary of said motor and before circuit in said primary is established, means for energizing the remainder of said coils from the second ary of said motor, and means for cutting out said first-named coils after said last-named coils have been energized.

17. In a controlling device for alternatingcurrent motors, a controlling-magnet having a plurality of coils, means constructed and arranged first to energize one coil or a number less than all of said coils from the source of current-supply to the primary of said motor and before circuit in said motor is established and second, simultaneously to energize the said primary and the remainder of said coils.

18. In a controlling device for alternatingcurrent motors, a controlling magnet having a plurality of coils, means constructed and arranged first to energize one coil or a numher loss than all of said coils from the source of current-supply to the primary of said motor and before circuit in said primary is established, second, to energize said primary and the remaining coils, and third, to break circuit in said first-named coils.

19. In a controlling device for alternatingcurrent motors, a controlling-magnet and a switch constructed and successively operating to close circuit to energize said magnet, to establish circuit in said motor and to break said magnet-circuit.

20. In a controlling device for alternatingcurrent motors, a plurality of electromagnets of different strengths, and movable armatures therefor, the said magnets having coils dis-- posed in the secondary circuit of said motor.

21. In a controlling device for alternatingcurrent motors, a plurality of electromagnets of dilferent strengths and movable armatures therefor, each of said magnets having a coil in circuit with the source of current to the primary and a coil in circuit with the secondary of said motor.

22. In a controlling device for alternatingcurrent motors, a plurality of electromagnets of different strengths, movable armatures therefor, each of said magnets having a coil in circuit with the source of current to the primary and a coil in circuit with the secondary of said motor, and means for establishing circuit first to said first-named coil and then to the motor primary.

23. An electromagnet having two coils, a movable armature therefor, means for establishing circuit first through one coil then through the other coil and then breaking circuit through the first coil, whereby said magnet remains energized by said second coil and attracts its armature; and means for supplying to said second coil a current of decreasing voltage, the said magnet being constructed and arranged to release said armature upon the current strength in said second coil decreasing to a certain predetermined limit.

24. A plurality of electromagnets, a movable armature for each, two coils on each magnet, means of establishing circuit through one coil of each magnet then through the other coil and then breaking circuit in the first coil whereby said magnets remain energized by said second coil and attract their armatures, and means for supplying to said second coil a current of decreasing voltage; the said magnets being constructed and arranged to release their armatures upon the current in the said second coils falling to a certain predetermined pressure different for each magnet.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

DAVID L. LINDQUIST.

Witnesses:

I. A. VAN WART, WM. H. SIEGMAN.

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