US1294147A - System of control. - Google Patents

Description

S. G. NOTTAGE'.

SYSTEM OF 001111101.

APPLICATION FILED FEB. 10. I916- Patented Feb. 11,1919.

2 SHEETS-SHEEI l.

Accelarafion in when foJ Fig. 5.

WITNESSES: o INVENTOR 2 PR4. WM v I ATTORNEY m: noun um. ca. rimummfnmmawu. n. c.

Stanley (31. Nohage.

S. G. NOTTAGE.

SYSTEM OF CONTROL.

APPLlCATION FILED FEB. 10. I916.

1,294,147. v Patented Feb.11,1919.

2 SHEETS-SHEET 2.

ad v Lk INVENTOR WITNESSES:

' .STomley G. Notraqe.

' 5 44% {WW ATTORNEY UNITED STATES PATENT OFFICE:

STA LEY e, vo r'rAenfo'riwitki isnuite, rEivNs irLvAnIA, assre von TO STING- HOUSE ELEcTmc ANIYMANUFACTURI G COMPANY, A CORPORATION or PENNSYL- vANIA.

0 all whom it may concern: H

Be it known that I,- SrAi'vLF i" G. NOTTAGE,

af'subject of'the'Kingof Great Britain, and I to full-speed "COIICl'llZl'OIlS, a relatively lowsh a resident ofWilkinsburg; in the county of Allegheny and State of Pennsylvamafhay'e invented a new and useful Improvement 1n Systems of Gontrol," of which the following is a specification.

My invention relates to systems of control and especially to the acceleration and-phaseregulationof induction motors and the l ke.

One object of my invention is to provide a'iiovel method and'ineans'of theaboveindicated character wher'eby inductionmotor orset ofmduction' motors maybeoperated= in'conjunction with speed-regulating means and phase regulating=means to produce a system that i'strelatively eflic1'entand that has other desirablezoperatmg characteristics.

More speeificauy stated, a is. an object of my invention to provide a-*method"and systern of the class under" consideration wh'erein a polyphase', variable resistor of relativ'ely ment of the secondary phase windings to effect motorac'celeratmn and wherein a pI1ase-advancing"machine of relatively highrunning-voltage" characteristics is subsequently employed for the usual purpose after thephase-windings have been re-arranged to produce a higher voltage combination under the new conditions. 7

Another object of my invention is to provide a relatively simpleand effective system of the above-mentioned type :for permitting,

the concurrent use of speed-regulating means, such as variable resistors,- and phase-regulating ineans,such as machines of the Leblanc type, in the operation of induction motors.

*lleretofore, in connection with theopera- "tion of-induction motors for propelling electric railway vehicles, for example, when liquid rheostats have been employed for accelerating purposes and phase-advancing machineshave been subsequently employed for compensating for the phase distortion that is causedby varying loads, certain limitations have been imposedv upon thei'designer of the apparatus by reason-of predetermined inherent structural and'operating characteristics of the liquid rheostat and the phaseadvancing machine. Liquid rheostats, in the present state of development, are wmost ""j sirs'r'EM or CO ROL.

7 Specification ofiLetter s Patent. 7 Pat t d F bpl 19,19.

' a inic' tibii filed February 1051916; Seria1NoJ77A31.

economically designed for maximum-starts mg-voltage operation of 700 to 800 volts, so

that, when theinduction motor is'accelerated or running voltage willobtain' in the secondary winding; thereby necessitating a relablanc type, for example, inherently operate -tobetter advantage under relatively lowcurrent and corresponding ,high-runnin'gvoltage conditions. It should be borne in mind that the above-mentioned high-running voltage will not'be likely to exceed thirty or forty volts in machines of the prior art, but, nevertheless, a doubling or other in- "crease ofsuchvoltage as is provided'inmy present invention Wlll effect a mater al de' crease of current, amounting in some cases to several hundred amperes.

chine for the low-voltage, high-curfent oper- 'ation'that has been necessary in the past, is

unavoidably expensive and diflicult.

' According to my present invention, I propendent secondary phase-windings initially "connected in a low-voltage combination, such as delta relation of, or parallel relation of sectlonsof, the respective phase-wmdmgs,

and I accelerate the motor to full-speed conditions in conjunctioniwith a liquid rheostat, whereby the necessary"low-starting-voltage,

highcurrent'-" characteristics are complied with'; while, after'the phase-windings have been short-circuited, which, of course, can be effected under full-speed conditions witharereconnected in a higlier voltage combination, such as star-relation, and a pliase advancing :machine having relatively highrunning-v'oltage, low-current characteristics is employed for-the usual regulating purposes. In order to permit the use of as ,many conductors'from the secondaryphasewindings as is'necessary, without requiring slip rmgs, wh1ch are relatively expensive and occupy valuable space in a locomotive, I make the primary winding of theinduction 'motor the rotor, whereby only a relatively :small number of slip rings is necessary, and

As will be un- "derstood by those skilled in the art, the construction of polyphase commutator mavide an induction motor having its inde- I make the secondary phase-windings stationary. Thus, the operation of the induction motor is effected in accordance with the required operating characteristics of the liquid rheostat and the phase-advancing machine in a relatively simple and reliable manner, as hereinafter more fully set forth.'

My invention may best be understood by reference to the accompanying drawings, wherein Figure 1 is a diagrammatic view of a system of control embodying my invention; Fig. 2 is a sequence chart of well known form for indicating the preferred operation of the various switching devices that are shown in Fig. l; and Fig. 3 and Fig. 4, and Fig. 5 and'Fig. 6, are views that correspond, respectively, to Fig. 1 and Fig.

2, of modifications of my invention.

Referring to Fig. l of the drawings, the

system shown comprises a plurality of suitable three-phase supply-circuit conductors A, B and C; an induction motor having a rotatable primary winding P and a stationary set of secondary phase-windings S; a variable accelerating resistor, such as a liquid rheostat LR; a suitable phase-advancing means PA; and aplurality of suitable sets of switching devices 1, 2 and 3, respectively.

The rotatable prime ry winding P is pref-- erably disposed'upon the usual type of rotor structure and is provided with a plurality of slip rings R1, R2- and R3 upon which bear brushes 1, 5 and 6 that are respectively connected to the supply-circuit conductors A, B and C through suitable conducting means 7, 8 and 9. The secondary stationary element S of the motor comprises a plurality of phase windings Sa, S?) and So that are independent the one of the other when the sets of switches 2 and 3 are opened, are connected in delta. relation upon the closure of tively connected, through conductors 16, 17

and '18, to .the corresponding terminals 19,

. 20 and 25 of the secondary phase-windings advancer armature.

Sb, Sc and Sa.

The phase-advancing machine PA may be of the familiar Leblanc or any other suitable type, and, as shown here, embodies a rotatable armature and a plurality of suitably spaced brushes 27 28 and 29 that bear upon the commutator cylinder 26 of the phase- Upon the closure of switches 3, the brushes 27, 2S and 29 are respectively connected with the remaining set V of terminals 30, 31 and 32 of the secondary phase-windings Sa, Sb and S0,- and the phase advancer armature is thus adapted to form a star-point in the secondary phasewinding system, while the liquid rheostat LR is connected to the set of terminals that are not associated with the phase-advancing armature. The phaseadvancing machine may be brought up to speed and driven by any suitable auxiliary motor, as is customary practice, and no illustration or description of such driving means is believed necessary. v

The switches 1 are merely adapted to short-circuit .the liquid rheostat LR- when they are closed, in accordance with a familiar practice.

Inasmuch as the particular type of governing system for manipulating the various switches in the desired sequence is immaterial to my present invention, I have not deemed it necessary to show or describe any such system. It will be understood that, in the case illustrated, a suitable master con troller of a well-known type may readily be supplied by those skilled in the art to effect the circuit connections that are indicated in Fig. 2. Moreover, if desired, a main-circuit controller havingcontrol fingers and conducting segments that correspond to the va-v rious switches that are shown in the figure may be utilized, if deemed preferable. Consequently, a sufficiently full and clear expositionof my invention is believed to be possible from a description of the maincircuit connections in conjunction with the sequence chart of Fig. 2.

Assuming that the primary winding P is connected to the supply-circuit conductors and that it is desired to effect acceleration of the induction motor, the operation" may be set forth as follows: By initially closing the switches 2, the secondary phase-windings are connected in delta relation, while the phase-advancing machine PA is entirely excluded from circuit since the switches 3 are opened; and the height of the electrolyte in the tank 10 of the liquid rheostat with respect to the electrodes 15 may be gradually varied in any suitable and well-known manner which it is not believed necessary to describe here. The motor is thus accelerated with the secondary phase-winding connected in a low-starting-voltage combination that is suitable for operation with the liquid rheo stat.

lVhen full-speed conditions of the rotatable winding P have been attained, the switches l may be closed to short-circuit the liquid rheostat and also the secondary phase windings, an operation which takes place without any undesirable or injurious results to the induction motor, since the 'secondary or slip voltage thereof under fullspeed conditions is relatively small, as will be understood.

To effect transition of the secondary phase "ratio of1.73 to 1, by the change to star relation from the delta running-relation that has heretofore been used. If it is desired to concurrently efi'ect phase-advancing and speed or slip regulation, the switches 1 may then also be opened, and such concurrent operationis permissibleby' reason of'thefa'ct that the phase advan'cing machine is connected to onecorresponding set ofterminals of the secondary phase winding, while the liquid 'rheostat is connected to the reinainingterminals thereof, and, aswill be understood,

only relatively low voltages will be impressed on the rheostat.

"In the prior art, one objection to the use of a phase-advancer in *con'ne'ctioawith an induction""'motor hasbeen' the impracticability of concurrentl 7 employing a phaseadvancing machinei nd a variable" resistor for the customary" function of regulating power-factor and speed "conditions, respectively, in the induction motor, since the two pieces of appai'atusrould be connected inparallel relation Y only.

A system whereby concurrent use of the i'eg'ula'ting'de'vices in question is permitted, is shown. and described and-claimed in a co-pending application of Hellmund, SerialNo. 59,825, filed Nov. 5, 1915 In theapplicati'on just mentioned, the relative location and connections of the phase-advancing machine and the variable-resistor are similar to those herein illustrated, whereby the de'siredconcurrent phase-advancing and slip regulation is permitted.

The chief reason for desiring an independent speed regulation of driving induction motors in electric locomotives, even during the period that phase-advancing machines are in operation, is the ability to compensate for 5 unavoidable 'diiferences in the diameters of the driving wheels that are associated with the various motors. As explained in the above-identified co-pending application,

ordinarily,where the terminals of the secis disposed upon the rotor structure, as is "customary, and, therefore, additional' slip rings, with their consequent disadvantages, are necessary. By the use of my invention,

however, the necessity for additional slip rlngs is obviated, as already explained, be-

cause of the fact that I employ the primary winding as the rotatableniember of the induction motor.

Referring now to'Fig. 3, the system shown "comprises the supply-circuit conductors, the phase advancing machine and the liquld rheostat, as already described in connection with Fig. 1 and, in additlon, an inductlon F motor having a rotatable primarywinding Pland a set S1 of independentstatio-nary niulti section secondary phase windings;

"and a plurality of sets of circuit-controlling switches 1, 11, 12, 13 and 14, respectively.

The primary winding P1 is similar in consti'u'ction tothe primary winding P of Fig.

1,whereas the secondary winding S1 comprises a plurality of star-related sets of phase-winding sections S10 and Sla, S16

and S17) and S10 and S10, respectively.

The switches 11 are respectively adapted to connect together the outer terminals of the phase-winding allied-sections; one of the switches 12 are similarly located with re spect to the remaining sets of phase-winding sections; the switches 13 are collectively adapted to connect the inner terminals of the phase-winding sections Sla, S11), and S10; and the switches 14 are adapted to short-circuit the armature commutator cylinder 26 of the phase-advancing 'inachine PA. The electrodes 15 of the liquid-rheostat LR are respectively connected through conductors 35, 36 and 37 to the outer terminals of the phase winding sections Sla, S16 and S10. The brushes 27,28 and 29 of the phase-advancing machine PA are respectively con nected, through conductors 38, 39- and 40, t0 the inner terminals of the phase-winding sections S16, Sla and S10.

Assuming that the primary winding P1 is connected to'the supply-circuit conductors A, B and C and that it is desired to eficct acceleration of the induction motor, the switches 11, 13 and 14 are initially closed, whereby the allied sections of the respective secondary phase-windings are connected in parallel relation, and the phase-windings, as units, are connected in star-relation. By suitably manipulating the liquid rhcostat LR, the induction motor may be gradually brought to full-speed in the relatively low-' starting-voltage, parallel-star relation just recited,'the phase-advancing machine PA being meanwhile inoperative by reason'of the closure of the switches14.

\Vhen full-speed conditions have been attained, the switches 1 may be closed for the I terminals of the allied phase-winding sec ,familiar purpose of short-circuiting the relation,

liquid rheostat LR, while, to efiect the desired transition of secondary winding connections to a high-running-voltage combination, the switches 12 may next be closed,

thereby completely short-circuiting the secondary phase winding, ,which is permissible for the reason already explained.

To-effect phase-advancing operation with the secondary phase winding in series-star wherein the voltage between secondary phase-winding conductors is substantially doubled relative to the initial parallel-star relation, the switches 11, 13 and 14 may then be opened, whereby the phaseadvanoing machine is operatively connected to the inner terminals of the phase-winding sections Sla, S16 and S10, and the allied sections of the respective secondary phase windings are disposed in series relation. For example, one circuit is completed from the brush 27 of the phase-advancer through conductor 38, phase-winding section S16, one of the switches 12, phase-winding section S15 and conductor 36 to one of the electrodes 15 of the liquid rheostat. Similar connections obtain for the other secondary phase-windings.

If it is desired to concurrently effect phase-advancing and speed or slip regula tion, the switches 1 may next beopened, whereby the liquid rheostat LR is connected to the outer set of terminals of the seriesrelated allied phase-winding sections, While the phase-advancing machine is connected to the remaining or inner set of terminals thereof, and thus the desired concurrent regulation is permitted.

Reference may now be had to Fig. 5, wherein the system shown comprises the supply-circuit conductors, the liquid rheotat LR, the phase-advancing machine PA and the primary and secondary induction motor windings P1 and S1, as set forth in connection with Fig. 2 and, in addition, a second induction motor having a primary winding P2 that is similar in construction to the primary winding P1 and is suitably mechanically associated therewith, as by a shaft or axle s, and a set S2 .of stationary secondary phase-windings that are similar in construction and arrangement to the set S1 of phase-windings; a second liquid rheostat LRl; a plurality of sets of switches 1, 11, 11a, 12 and 13 that are associated with the set S1 of secondary phase-windings and the liquid rheostat LR; and a plurality of similar switches 21, 21a, 22, 23, 41 and 14 that are associated with the set S2 of secondary phase-windings, the liquid rheostat LRl and the phase-advancing machine PA.

The switches 1 and 11a are respecti ely adapted to connect the outer and the inner tions; the switches 12 and 13 perform functions similar to those already described in connection with Fig. 2; the switches 21, 21a, 22 and 23 respectively correspond to switches 11, 11a, 12 and 13; the switches 41 are adapted to connect the liquid rheostat LE1 to the set S2 of secondary phase windings, while the switches 14 are adapted, upon the opening of switches 41, to cause the phaseadvancer PA to replace the liquid rheostat LRll.

Assuming that the rotatable primary windings P1 and P2 are connected to the supplycircuit conductors and maintain identical space-phase relations by reason of the mechanical interconnection, the acceleration of the induction motors may be effected by initially closing switches 11, 11a, 13,21,21a and 41, whereby each secondary winding is connected in star relction and with a resistor in circuit therewith.

The sets of secondary phase windings of the two induction motors are thus initially connected in series relation, considering that the liquid rheostat tanks are in reality interconnected by reason of the usual practice of grounding such tanks, whereby a relatively low-voltage combination is employed in connection with liquid rheostat'operation during the accelerating period. However, in some cases, it may be advisable, when starting, to isolate the secondary windings to prevent possible double voltages on one rheostat, but, usually, the above-described series relation is permissible.

When full-speed conditions have been attained by suitable manipulation of the liquid rheostats LR and LE1, switches 1 and 14 may be closed, whereby the respective liquid rheostats are substantially short-circuited through the switches 1 alone and through the switches 14 and the relatively low -resistance armature windings of the phase-advancing machine PA, respectively. To efi'ect the desired transition of the motors from the lower-voltage, series-parallel-star combination, just described, to the desired new higher-voltage, series-star combination, the switches 12, 22 and 23 are first closed, thereby short-circuiting all of the secondary phase-windings in accordance with the op- 'e'ration already mentioned, and switches 11,

11a, 13, 21, 21a, 23 and 41 are next opened. Consequently, one circuit is established from one of the switches 1, throughconductor 35, phase-winding section Sla, switch 12, phasewinding section Sla, conductor 45, phasewinding section S2a, switch 22, phase-winding section S2a, conductors 49 and 52 and switch 14 to one of the brushes of the phase advancing machine PA. Similar circuits obtain for the remaining groups of correspond ing secondary phase-windings, and it is not believed to be necessary to trace such circuits in detail. It should be observed that, by the closure of the switches 14: and subsequent opening of switches 41, the phase-advancing machine PA replaces the liquid rheostat LE1, the respective brushes of the phaseadvancing machine being connected through conductors 51, 52 and 53 to the conductors 50, 19 and 48. Phase-regulating operation is thus effected with the secondary phase windings connected in a relatively high-running-voltage combination, whereby a still further reduction of current and corresponding increase of voltage during the phaseadvancing period may be accomplished.

If it is desired to effect concurrent phaseadvancing and slip regulation, the switch 1 may be opened, whereby the liquid rheostat LR is associated with one set of terminals of the above-outlined series phase-winding circuits, while the phase-advancing machine PA is connected to the other terminals of such circuits, and the desired concurrent op eration may be accomplished in a manner similar to that set forth in connection with the other systems.

It should be noted that the system just described may be readily adapted to permit cascade operation of a plurality of induction motors, if such operation is desired in conjunction withthe use of my present invention.

I have thus provided a number of induction motor systems wherein relatively lowstarting-voltage combinations are employed in conjunction with variable resistors having low-voltage characteristics during the accelerating period, and, after the motors have been accelerated to full-speed conditions, the terminals of the secondary phase windings are indiscriminately short-circuited and then opened at the points which afford the desired reconnection that corresponds to the high-running-voltage, lowercurrent combination, whereby a phase-advancing machine may be more economically operated for the usual regulating purposes. Moreover, the concurrent use of speed-regulating means and phase-regulating means is permitted in a relatively simple and inexpensive manner by the use of my invention.

I do not wish to be restricted to the specific circuit connections or location and arrangement of parts herein set forth, as, obviously, various modifications thereof may be made without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a system of control, the combination with a supply circuit, of an induction motor having a primary winding and a plurality of independent secondary phase windings, a variable resistor, a polyphase commutator machine, means for initially connecting said phase windings in delta relation, means for employing said variable resistor in circuit with said phase windings to effect acceleration of the motor, means for reconnecting said phase windings in star relation for operation under full-speed conditions, and means for connecting said commutator machine to said reconnected phase windings.

2. In a system of control, the combination with a supply circuit, of an induction motor having a primary winding and a plurality of independent secondary phase windings, a variable resistor, a phase-advancing machine, means for initially connecting said phase windings in delta relation, means for connecting said variable resistor in circuit with said phase windings to effect acceleration of the motor, means for reconnecting said phase windings in star relation for operation under full-speed conditions, and means for connecting said phase-advancing machine to the phase-winding terminals not connected to said variable resistor, whereby power-factor and speed regulation of the induction motor may be independently obtained.

3. The method of operating an induction motor having a primary winding and a plurality of secondary phase windings in conjunction with speed-regulating means and phase-regulating means that consists in employing said speed-regulating means to accelerate the motor with a relatively lowvoltage arrangement of the phase windings and subsequently rearranging said phase windings in a higher-voltage combination and employing said phase-regulating means.

1. The method of operating an induction motor having a primary Winding and a plurality of secondary phase windings in conjunction with a variable resistor and a phaseadvancing machine that consists in employing said variable resistor to accelerate the motor with the phase windings arranged in delta relation, short-circuiting said phase windings when full-speed conditions are attained, rearranging the phase windings in star relation and employing said phase advancing machine.

In testimony whereof, I have hereunto iubscribed my name this 31st day of Jan.,

STANLEY G. NQTTAGE.

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

Washington, D. G.

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