USRE16540E

USRE16540E - Best available c

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Publication number: USRE16540E
Authority: US
Publication date: 1927-02-08

Description

BEST AVAILABLE cow 0. c. TRAVER SYNCHRONIZING DEVICE Feb. 8,1927.

2 Sheets-Sheet 1 Orijunal Filed July 29, 1922 Q Oliver C. Tra I T igll BEST AVAILABLE cob Feb. 8. 1927. TRAVER 16549 SYNCHRONIZING DEVICE 2sh tssha*.2 L 2 Original Filed July 29, 1922 Fig.5

lnVen -i: or: Oliver C. TT-aVeT';

I-lis J T-thorn e5 Reiuued Feb. 8, 1927, i 5

UNITED STATES s'r AVAILABLE com ISSUED:

PATENT OFFICE.

OLIVER C. 'LBAVER, OI SCH EHEC'I'LDY, NEW YORK, 'ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYHCHBONIZING DEVICE.

Original Ro..1,583,1 20, dated November 24, 1825,

P tot reissue filed December My invention relates to improvements in synchronizing devices and has for an object to provide an improved synchronizing de vice for automatically controlling the operation of connecting an alternatin current dynamo electric machine to an alternating current electric circuit whereby the connection can be made substantially only at the inst-ant when the electromotive forces ofthe machine and circuit are alike in frequency, phaseand value. My invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. s Figure 1 illustrates diagrammatically an embodiment of my invention, and Fi 2 to 11, inclusive, are vector dia 111113 57118: trading the rinciples uponwhic "my invention is ror purposes of illustratioml have shown in 'Fig. 1 anembodinient of my invention as applied to a three phase alternating current electric system comprising an alternating current electric circuit such as a bus 1 to which may be connected one or more dynamo electric machines 2 or sources of alternating current in parallel-as is wellknown to the art. I have illustrated the dynamo electric machine 2 as an alternator adapted to be connected to the bus 1 by any suitable circuit controlling means 3 arranged to con- ,ftrotn cireuit between the bus 1 and the alter iiator 2. The circuit controlling means 3 preferably comprises an electroresponswe closing means such as a closing coil 5 connected in a control circuit 6 which may be.

connected across a control bus 7, and which may include an auxiliary switch S m-ranged to be controlled by the circuit controlling means 3 so as to he closed when the {circuit controlling means uis v open and o en when the circuit con'tmllinflmeans is closed.

For controlling"thc'control circuit 6, I provide electroiesponsivc means comprising a plurality of circuit controlling members 9,110 and 11 which are arranged to control 7 contacts 12, 13 and 14: or 15, respectively,

ur-runpd in series in the control circuit 6. Th im (Jilin! ty of, diflerentially'eetingjglectronaive means, may comprise Serial No. 578,475, filed July 29, 1922 App1icat1on a, 1926; smnm. 158,046.

disk motor type, each element comprising an induction disk and a plurality'of motor elements arranged to exert opposing torques thereon.

' For energizing the motor elements of the

formers

19 and 21 are connectedin circuit for o posing 'electromotive fi forces when their e ectromotive forces are in phase and the secondaries of the

transformers

20 and 22 are connected i'njcircuit 'for' cumulative electromotive forces when their BIGGHOIHG? tive foroes'are in use -The relay 16 iv ich controls'circuitj'controllin member 9 may comprise an induction disk 23, shaded pole motor elements 24 and 25 arranged toexert opposingtorques thereon, and suitable-means such as a drag magnet -26 for exerting a retarding force onthe disk 23 so as to obtain a time delay action in the movement thereof.

Movement of the disk 23 in jib; direction to member 9 away a from circuit closing po'srtionfis limited by any suitable means such as astop- 26" Thej carry circuit controllin position of the stop 26? relatively to the contacts 12 may be determlnedin accordance with the angular movement of the disk 23 necessary to provide the time "delay desired" and ;in a'practicul embodiment of myinvention I have arranged the sto') 26' and the contacts 12 so that the disk 2l may have an angular movement of approximately 180 Motor element 24 is provided'zwith an-energizing winding 27 connected in series relatiori'vvith the secondaries of the potential transformers 19 end'21 andmotor element 25 is provided .with an energizing winding 28 connected 1n seriesrelation with the sec: ondaries of a the

potential transformers

20 and 22. The'motor 'elements'2 tfand 25 tend to exert opposing torques {the disk 23 irrespective or the directions of current flow in their windings 27, and 28, respectivel The relay 17 which controls :circuit ion trolling member 10 may comprise an induc- 'f tion disk 29 and shaded pole'fm'otor elements 've devicesgor relays 16 17 am- 18 h be oftbe shaded pole induction 3Q; and-"31 arranged to exert opposing BEST AvAiLAeLE COP\ torques thereon. Motorelenient 30 is provided with an energizing winding 32 connected in series relation with the secondaries of. th

transformers

19 and 21, and motor element 31 is provided with an energizing winding 33 connected in series relation with the secondaries of the transfoi-uiicrs and. 22. The motor elements 30 and 31 tend to exert opposing torques on the disk 29 irrespective of the directions of current flow in their windings and 33 respectively. The disk 29 is so shaped and. the shaded poles of the motor elements 30 and 31 so arranged with respect to the disk 29 that in the event of either of the motor elements 30, 3]. predominating to turn the disk 29, the torque exerted by the stronger element is increased while the torque exerted by the weaker element is decreased. One way to obtain this effect is'to remove a segment of the disk 29 and arrange the shaded poles as shown so that an increasing area of the disk is presented. adjacent the shaded pole faces of the motor'element tending to exert the greater torque and a decreasing area of the disk adjacent the shadedpole faces of the motor purpose. of maintaining itself in engagement with its cooperating contact. The contacts with the depending portions 40 also act to limit the movement of the disk 35 in either direction and tend to return the disk 35 to an intermediate position when the torques exerted by the motor elements 36 and 37 are substantially equal.

For the operation otmysynchronizing device. it will. hc'dcsirable to refer to Figs. :2 to 11, inclusive, which are vector diagrau'is illustrating the principles upon which my invention is based. In these diagrams, the heavy solid lines designated E and shown in a fixed position as a reference line, represent the voltage on the bus 1 or a voltage proportional thereto as, for example, the voltage across the secondary of each of the transformers 19 and '20. The heavy solid lines designated 6 represent the voltage of the alternator 2 or a voltage proportional thereto as, for example. thevoltage across the secondary of each of the transformers 2i and 29. in accordance with the phase relation of the two electromotive forces to he vsynchronized.

element tending to exert the smaller torque.-- e heavy dashed ii'nesdesignated fl p sent the voltage c reversed The vectors E, r e ande assumed equal in length as This construction and arrangement of parts also provides for a quick positive movement of the disk 29 substantially of the nature of a snap action which is desirable. Movementof the disk 29 in a direction to carry circuit controlling member 10 away from circuit closing position is limited by any suitable means such as a stop 34.

The relay 18 which controls circuit controlling member 11 may comprise an induction disk 35 and shaded pole motor elements 36 and 37 arranged to exert opposing torques thereon. The motor element n6 is provided with an energizing winding 38 connected across the terminals of the secondary o'l' transformer 21 and the motor element 37 is provided with an energizing winding 39 connected across the terminals of the secondary of the transformer 19. The motor elements 36 and 37 tend to exert opposing torques on the disk 35 irrespective-of the directions of current flow in their

windings

38 and 39 respectively. Obviously when the motor elements 36 and 37 exert equal tor ues, that is to say. when the voltage of the a ternator 2 is substantially equal to the voltage on the bus 1, the disk will tend to remain stationary and the contacts Hand 15 closed.

but uponthe occurrence of a predetermined difference in these voltages, the disk 35 will be turned in one direction or the other toopen either contacts 14.01 15." One of the con.1..-icts of ea h of the pairs otcontacts 14L .i2id .15 1'ii;iy be provided with a -depending or tzail portion 40 extending into the path of mmement of the circuit controlling mernber 1i and each of these contact members may also be --s-;iliently mounted for the this is awondition for controlling the con trol circuit 6 under the control of relay element 18 or other equivalent means. The light solidllnes designated .a: and yrepresent the vectorial dilterenees of E and e. and E and s. respectively, that is to say, .00 repicsents the vcctorial difference and 3/ the rectorial sum of E and e. The voltages :r and 3 in accordance with their relative values control the operation of the relay elements 16 and 17. For convenience, the vector diagrams are assumed to be divided into four The vector (2 is assumed to rotate quadrants a, t), o, andd respectively as indicated in Fig. 10- I Fig. 2,1'epnesents the iii-phase condition of the voltages on the'hus 1 and the alternator 2. In this case, the vectors E and e,

coincide. w is zero and 7 has its maximum value. N

Fig. 3 represents the voltage of the alternator less than 90 degrees out of phase with the voltage on the bus 1, that is to say volt-v age in quadrant a. In this case, voltage 1/ .is greater thanvoltage m.

Fig. 4 represents the voltage of the alter nator 2, 90 degrees out of phase with the,

voltage on the bus 1. In this case, volta 71s a? cquals voltage 3/.

nator 2 more than 90 degrees and less than 180 degrees out of phase with the voltage on the bus 1, that is to say. voltage a in quadrant 6. Inthis case voltage y is lcssithan voltage :12;

Fig. 6 represents the voltage of the ziflti nator 2, 180 degrees out otphase with tl e Fig. '5- represents the voltage of. theallcri sesr AymLAeLE' com 16,540:

the bus 1, that is to say, voltage 0 in quadrant 0. In this case voltage (0 is greater than voltage y.

nator 2, 270. de rccs out of phase with the voltage on the ms 1. In this case, voltage :2: equals voltage 3 Fig. 9 represents the voltage of the alter nator 2, more than 270 degrees and less than 360 degrees out of phase with the voltage on the bus 1, that 1s to say, voltage 6 1n quadrant d aprolchin phase coincidence with voltage E. In the case voltage 3/ is greater than voltage 0.

Fig. 10 is a summary indicatin the relative values of the voltages at an 3 in the diflerent quadrants and under the different 00 ditions heretofore considered.

rom these figures, particularly Fig. 10, and assuming disk '23 not retarded in its movement and disk 29 circular and motor elements24 and 25 and also and 31 to be so alike in features of construction that, when their respective windings 27 and 28 and also 32 and 33 are ua ly energized, equal torques are prod it will be ohserved that through a certain range of phase difference, viz, 90 degrees to 270 degrees or when volt-a e y is less than voltage 0:, as in quadrants and c, motor'elements 24 and 30 would predominate to turn their respectivel disks counter clockwise. that is, the disk 23 to circuit opening position and the disk 29 to circuit closing sition and that through another certain range of hase difference, viz. 270 dcgrcesto 9O cgr'ees or when voltage 1/ is greater than voltage :0, as in quadrants d and a, motor elements 25 and31 would predominate to turn their

disks

23 and 29 clockwise, that is, disk 23 to circuit closing position and disk 29 to circuit opcnin posit ion. Under these conditions the dis. s '23 and 29 would notsimultaneously be in circuit closing position.

In order that the-circuit controlling means 3 may he closed only when the electromotive forces of the bus 1 and alternator 2 are substantially alike in phase, frequency and value. I so construct and arrange the relays- 16, 17 and 18 that the movable elements thereof must simultaneously he in predeter- ""mmed positions. For tins purpose, I may construct the rcspcclivc motor-elements of relays 16 and 17 oi dillcrcnt strengths and provide means for retarding the movement of the disk 23 and also arrange the dislrlZll to provide differential click-ts. The motor elements 36 and 37 of relay 18 may be sub stantinll v similar in construction so as to permit the contacts 14 and 15 to remain Fig. 8 represents the voltage of the altergig closed when the difl'erence in voltages of the alternator 2 and-bus 1 is "within a predetermined amount which in :1 practical embodiment of my invention, 1 have taken so that thevoltagcs must be within five per cent of each other.

Referring now to Figs. 1 and 1i. motor clement may he so constructed as to predominate over motor element 24 to start disk 23 moving to circuit closing position when voltagee has reached a. POSli'lOl'l 6 prior to phase, coincidence Where voltage 3; has 9.

Ill

value 1/, and voltzwe m l-lie corresiondin value :0. and contacts 12 will be closed with a time delay, and when voltage 6 passes through phase coincidence to a position 6 where w and 3, again have substantially the same values 11: and 3 motor element 2% Will predominate and more dish 23 to circuit opening position; In a practical embodiment of my invention voltages fr end y, have substantially the values 40 and 220 volts respectively. Thus, as voltage e moves to and away from phase coincidence through the range of phase diiicrence from 6 to e disk 23 will he moved toward. circuit closing position "with u limcdciav, while in the range of phase difference iron: (2 through phase opposition to 6 disk 23 will be moved toward circuit opening position, For the values of the voltages :0 and y and the action herein set forth. it will be obvious that motor element 24 should be constructed to exert the predominant ,torque "when voltage :0 is greater than 40 volts and voltage 3 less than 220 volts. In which case motor element 25 will exert the predominant torque whenvoltage or is less than 40 volts and voltagey' greater than 220 volts. i

The position (2 of tl l c yoltuge e, Fig. 11 corresponds to theplirts in position as shown in Fig. 1. lo t l 3 position, more of the disk vention, the particular position of a profcrahly, for practical purpo 0'', just before phase coincidence as this allows somewhat:

for the time necessary to close the circuit.

controlling means 23, In {1 practical Qnll)()(llinvcntizm; motor clement 317s CUHFiI'llCi l (r 22ml roach substantially the values El) and 221) volt; rcerpcctivcly. \Vhcn motor clcn'wnt ll predominates to more the disk '29 c-hu-lcwic and iucrczlsing area of the disk 2.) will hprescntcd urlinccnt'il's pole flies? and a decreasing urea, adj melt the pole faces lo prcdouainzilc when voltages BES'i AvAtLABLE COP.

(l(i'i'0:l't accordingly in order that motor ele-.

meat 230 may' predominate to move the disk 25) to circuit closingpositiona. 'In order to in--ure that the disk 29 may'not move to circuit closing position until after the disk '23 has moved to ciicuit opening position, I construct the motor elements 30 and-31 so that with the disk 29 in circuit opening position. the voltage (3 must reach a position a,

such as, for example, substantially quad-- rature orlh) degrees from phase coincidence where voltages w and 7/ are substantially assumed that the voltages of the alternator '2 and bus 1 are equal so that contacts 14: and 15 remain closed. If these voltages are not equal one or the other of the contacts 14 and Consequently voltage in will equal, (see Fig. t) before motor element iiO- ran predominate to more the disk 29 to circuit closing position. tion of e, is immaterial, the main requisite living that the position of c where motor ole incnt circuit closing position should be in phase disp1ace1nent subsequent to theposition e, where motor element 2% predominates to more the disk :33 to circuit opening position. In a practical embodiment of my in- Yentiou, the values of the voltages to and ;1 wherein two sources of alternating e1ec tromotive force are to be synchronized, a-

correepouding to the position a, of the Yoltage (1. are each substantially 150 volts. \Vh'cn motor elc1'nent'30 predominates .to more the disk 2'. to circuit closing position, the disk The particular posi-Q 0d predominates, to move disk 29 to.

(NW) Fig. 1) will remain substantially in this position until voltage 6 reaches the, positiou when motor element ill will again predominate and more the disk 29 to circuit opening position as heretofore set forth. Thus. as voltage moves to and away from phase coincidence through the. range of phase ditl'crcnce fromc to e,, the disk 29 will lie in rircuitopening position while in the range of phase difference from (2 through phase opposition to (7,, the disk 29 Will be in circuit closing po ition.

It will therefore lie-obvious that the differenro between the frequencies of the alternator and has voltages must be less than a Pl'tt'ltitll'lllj]l((l amount in order that the disk -0 may have time to more to circuit closing position before disk 29 is moved to circuit opening position. lilorcovc'r, the range ol phase dill'crcnce over which both the disk 23 'an'd flll ,may simultaneously he in circuit closing position is limited and conseqimntl the control rircuitii can be completed only during a limited number of degreeslrefore synchronism and not after. This somewhat for the time required to close the circuit controlling means 3. It is, of course,

allows 15 will he'opened in consequence of the differential action of the motor elements 36, 37 on the disk 35 and therefore the control air-'- cuit 6 will he held open even thou h the al-.

ternator voltage has thesame reque'ncy as, and is in phase with-the bus voltage. It is therefore clear that the control eircuitfi controlling the operation of closing the cit cnit controlling means. 3 can he closed only when the voltages of the alternator 2 and the bus 1 are substantially alike' in phase, frequency, and value. It is moreover clear from Fig. 11 and the explanation therewith.

that contacts 13 which open just before synchronism remain open until degrees or more after synchronism since motor element 31 of relay 1'? tends to predominate until the voltage-e is substantially 90 degrees beyond phase coincidcnce.-

Although I have shown and described my invention in considerable detail, I do not wish to be limited to the specific details thereof, as shown and described, but may use such modifications, substitutions or equivalents thereof, as are embraced within the spirit of my invention. v

lVh-at I claim as new and desire to secure by- Letters Patent of the United States is: 1.In a system of the class described switch for connecting the sources, and means for controlling the closing of said switch, comprising a plurality of relays connected and arranged so that the movable elements of the respective relays must simultaneously he in predetermined positions to enable said switch to be closed, one of said relays being connected to said sources of eleetromo tire 'force and arranged to tend to move to .switch closing position during a predetermined. range of phase diiferencefbetween the 'elec'tromotive forces near phase co-inieidence and tending to move away from switch closing position when the phase difference is outside of this range, means for delaying the operation of' said relay whereby it can reach switch closing position during the predetermined range of, phase difference only when the frequencies of said clcctromotive' forces are'- substantially 'the same, another of said relay being connoct ed to said'sources of electromotiv'e force and arranged to remain in switch closing position during a range ot' phase difi'erencc beginning suhsequentlyto the-ending oi said first range of phase difference and ending substantially at'phase eta-incidence, and to llo then move quicklyout of switch closing is position, and means connected to said sources of elcctrorno'tive force and arranged-toper mita an can let a;

BEST AVAILABLE cop the'samevalue. Q g I 2, alternating current electric systhe electromo'tpve have substantihlly temiwher'ein two sources of alternating elec" 'tromotiva' tdrce ire to he s; nchronized,'

-' means adaptedto be operated to connect said sources, and means for flectin the operation of said connecting means w en the electromotive forces of sr sources are in synchronism, comprise -1 a control circuit, a

' plurality of contacts arranged in series in said control circuit and a plurality of relays for controlling said contacts having energizing windings connected in circuit with said sources to render said rela a responsive to the phasii relation of sai electromotive -force s, one of said relays bein p ase difierence tween said electromotive cross to close the contacts controlled there- -0 rative in respznse to a predetermine by and upon the occurrence of a smaller predetermined phase difference to open and contacts and another of said relays bein operative in res nse to a predetermin phase diflerencetween said electromotive forces with stime delay such that the contacts controlled thereby are moved to circuit closing position while said first contacts are in circuit closing ference between t s frequencies of said electromotive force is below a predetermined d 7 v 8. In a system of the class described wherein two sources of alternating electromotive force are to be synchronized, a switch for connecting the sources" her and means forcontrolling the closing 0% said switch, comprising a luralityof relays connected and arra so that the movable elements of the respective relays must simultaneously be in predetermined positions to enable said switch to be closed, twovof said role 5 each having windings connected to be in ividually responsive to a resultant of theinstantaneous values of the electromotive forces to be synchronized, one of the windings on cache-clay being arranged to tend to move theelement of the relay oppositely to the tendency of another winding to move the element so that movement of the. element of each of said relays depends upon the differential effects of thewindings nected so that'wben theelectromotive forces are in phase one winding approaches its maximum effect and the other winding its minimum effect, one of said relays being arranged to tend to close while said electro-'- motive forces are within a predetermined ran of phase difl'erence, means for retar. mg the. operation of said relay so that the element thereof can reach circuit closing uenciqflf the position only when the electromotive' forces are an the on said member, one'of aaid ition only when the dif- 0 881 evicea com ber, contacts the other in accordance with there on, the windings on each relay being conmme, the other relay constructed to remain closed during a p etermined range of phase ditference whilesaid electromotive forces are approaching phase coincidence and to move quickly away from switch closing position when the electromotive forces, are substantially in phase whereby the switch can be closed only when the frequencies of the eleetromotive forces are so nearly the same as to permit chronizing (Ii and only-during an interval w e the electromotive forces are approaching phase coincidence and their base difierence is within a predetermin range. I I

4. In. an alternating current electric sys 0 tom wherein the electromotive force of an alternating current dynamo electric machine is to be synchronized with the electrbmotiva force an alternating current elect'riccircuit, synchroni means comp a plurahty of coopera 'ng electroresponaive devices, one of, said devices comprising a movable member, contacts" controlled by the movement thereof, and a plurality of motor elements arranged to exert oppoamgtorques elements being connected -in circuit to be energised in accordance with the vectorial same! and another in accordance with the veetorial difierv ence between said-electromotive forces, the construction and tolparts such at said mu operate to move mem tocon o'sing 'timn' n e occurrence of a. difleb' enc'e between sa' elech'omotive andto I move said member hom contact closing positionj-upon the occurrmce of a smaller pr another mun- WI; 1 thereof, means for retarding dia movement of said member, and a pin i d'motor elements arranged to exert op 'on'said; I, one .id I connccted in circuit to be [in accordance with the vectorial sum of and anthe diflerence between? said forces whereby movement of'aaid to tact closing position is elected in dance with the phase difference betwefi v tromoti ve forces, the construction tend arrangengsnt of. parts bein such that when, the di erencebetween t frequencies of saidel ectromotive forces exceeds a predator 1Y mined amount said member will tend toreach contact closing position subsequently to the-movement of said first member from contact closing position. I

5 In an alternating current electric system wherein two sources of alternating elec-' tromotive force are to be synchronized, 1 means for connecting the sources, and means for controllinggtlwicl of s m s comprises a r d BEST AVAILABLE COP ating electroresponsive devices, each of said devices comprising a movable member and.

having energizing windings arranged to exbeingconnected in circuit with said sources crt opposing effects thereon, the energizing windings of each of two of said devices to be energized respectively in accordance with the sum of and difference between the instantaneousvalues of the electromotive forces render the devices operative in response t6 the phase relation thereof, the

movable member of one of said two devices being opera ive in response to a predeter-i ;mined phase difference between said elec-- troluotive forces to move to'circuit closing position and to moveto circuit oening position in response to a smaller pre etermined phase difference and the other of said twodevices comprising means for retarding the movement of" the movable member thereof whereby the member is operative in response to a predetermined phase difference between the electronlotive forces to move to circuit closing position with a "time delay such that when the dill'erence between the frequencies of said electromotive forces exceeds apredetermined amount circuit closing position is reached subsequently to the movement of said first member to circuit opening position, and another of said plurality of devices having the energizing windings thereof connected in circuit with said sources to he energized in accordance with the respective values ofthe electromoti've forces there ot'whereby'the movablememher is moved to circuit opening position upon the occurrence of a predetermined difference between the electromotive forces, the construction and arrangement ofpar'ts being such that the movable elements of said pluralityof electroresponsive devices must simultaneous-' ly b in predetermined positions, to enable said connecting means to be closed.

(5. In an al ernating current electric system wherein two sources of'alternatin electromotive force are to be synchronize ,syn! chronizing means compris ng a control c1rcnit and aplurality of cooperating electroresponsive devices for controlling said cir-. cuit, one of said devices comprising arotata ble contact controlling member and, a plurality of motor elements arranged to exert opposing torques thereon connected in'circuitwith said sources to be, energized in accordance with the vectorial sum of and difference between the electromotive forces thereof respectively, the construction and arrangement of parts being suchthat upon the occurrence of a predetermined phase difference between the electromotive forces said member is quickly moved to,circnit .closing position and upon the occurrence 015B, small er predetermined phase difireue e is quickly moved to circuit opening positiom i-another of devices comprisingja rotatable ccntively movable tact controlling member, means for retarding the movement thereof and a plurality of motor elements arranged to exert opposing torques thereon connected in circuit with said sources to he energized in accordance with the vectorial sum of and. difference between the electromotive forces thereof respectively, the construction and. arrange ment of parts being such that upon the occurrence of predetermined phase diflerence between the electromotive' forces member is moved to circuit closing position with electromotive forces of said sources are substantially equal and in synchromsm, comprising a controlcircuit, a plurality of relacoopcrating contacts arranged in' series in said control circuit and a plurality of relays for controlling said contacts, two of said relayshaving energizing windings connected in circuit with said sources to render said relays responsive'to the phase relation of the QlGCUOIIIOtlXG forces' thereof, one ofsaid two relays beingoperativeiin response to a predetermined hase difference between the electron'iot-ive orces to close the contacts controlled. thereby and hold them closed until the occurrence of a smaller predetermined-phase difference be tween said electromotive forces, and another of said two relays being operative in response'to a predetermined phase difference between said 'electroniotive forces with a time delay such that thecontacts controlled thereby are moved to circuit "closing position wl'iil'esaid first contacts a e in. circuit closing position only when the difference between the frequencies of said electrometivefo'rces is below a predetermined value ,and another of said plurality of-relays haw Jug energiz ng-,w1ndmgs connected;- in; circuit with. said. a creator and said circuit re spectivelytorender said relay'operativein response to thedriference between said electromotive force's wherehythe contacts controlled thereby are moved to circuit opening position upon the occurrence of a predetermined. difference between said: electromotive forces,

8511: an alternating current electric systernjwherein two sources of alternating electroznotive force 7 are to be synchronized, means for connecting said sources, means REST AVAlLA BLE o oe a i comprising a control circuit for effecting the operation of said connecting means, and means for controlling said control'circuit comprising a. plurality of electroresponsive devices each including a rotatable member,

' contacts controlled thereby and arranged in connected in circuit tofbe energized in accordance with-the sum 0 the electroniotive forces of said machine and said circu1t and the one gizing wind ng of another of said elements connected in circuit to be energized in accordance with the difference between said electromotiveforges whereby said devices are responsive tothe phase 'difierence and difference between the frequencies of said electromot'ive forces, the rotatable mem' ber of one of said devices being. adapted upon movement thereof in res use to the occurrence of a difierence tween the torques exerted thereon by said motor elements to increase the efi'ect of the element exerting the greater torque and decrease the v occurrence of a smaller pr efi'cct of the element exerting the smaller torque whereby the predominant motor elementis rendered more effective, the construction and arrangement of parts being such that said motor elements operate to move said member to contact controllin "position upon the occurrence of a pre etermined phase difierence and to hold said member in contact closing ition until the ed t ermined phase, difference, and another of said devices comprising means for retarding the movement of the rotatable member thereof, the'constructionand arrangement of parts being such that when the difierencebetween the frequenciesof said electromotive forces is below a predetermined value said rotatable member is caused to-move to contact closing position while the contacts of said first de-/ vice are closed whereby said control circuit is completed to effect the closing of said.

. connecting means.

9. In combinatiomtwo alternating current circuits, switching means for connectin the circuits, and means controlled in accor anoe with the phase relation and the dificrence between the frequenciesof the electromotive forces of the circuits for starting the closing operation of the switching means only when the phase difference of the electromotive forces exceeds a predetermined value and the difference between the frequencies of the electromotive forces is less tham'la predeter mined value.

10. In combination, two alternating current circuits, switching means for connecting the circuits and-meansconnected to be energized in accordance with the ditference between the eflects of the sum. of and the difference between the electromotive forces of the circuits for starting the closin operation of the switchin means'only wli en the phase difference of the electromotive forces exceeds a predetermined value and the difference between the frequencies of theeletn tromotive forces is less than a predetermined value. k

11. In combination two alternatin current circuits, means for controlling the interconnection of said circuits comprisinga control circuit, a relay responsive to condi' tions in said circuits operable to niakeua connection .in the control circuit only during a predetermined range of phase difierence between the electromotive forces of the circuits when the diflerence between the fre-' quencies is less than apredetermined value and a relay res naive to conditions in said circuits operab e within said range to control another connection in the control circuit. a

12. In combination. two alternating current circuits, means for controlling the interconnection of said circuitscomprising a control circuit, a rela connected and arranged .to be energize in accordance with the sum of and the diflerence between the electromotive 'forces of the circuits operable to make a connection in the control circuit on] durin .a predetermined range of hase di erence tween the electromotive' orces when the frequency difference between the clcctromotivc forces is-less than aredetermined value, and a rclay connects and arranged to be'energized 1n accordance with thesum of and the difference between the.

electromotivo forces operable-Within said range to control another connection in the control circuit.

13., In combination, two alternating cur-.

rent circuits, a switch for connecting the circuits, and means for cont-rolli the closing of the switch comprising a p urality of relays connected and arranged so that the movable elements thereof must simultaneousl v he in predetermined positions to start the closing operation of the switch, one of said relays being connected to said circuits and arranged to tend to move to switch closin position during a predetermined range 0 phase difl'erencehetween the electromotive forces of the circuits and to move from switch closing position when the phase difference is. outside this range, means for delaying the operation of said relay whereby the relay can reach switch closing: positioir only when the difference between the freuencies of the electromotive forces is less t an a predetermined value, and another of said relays being connected to said circuits and arranged -to remainin switch closing position during a rangeof phase dill'erenee BEST AVAILABLE cop beginning subsequentlyfto the eiidof said iii-st range of phase difference and ending prior to phase coincidence and then to .move

quickly-'outof switch closing position. I

14'. In;combiitat ion, .two alternating curqrent circuits, 9. switchior connecting the ciredits, and meansfor 'controlli'ngqthe closing of theswitc'h comprising a, plurality of relays connected and arranged so that the movable elements thereof must simultaneously be in predetermined positions to start the. -closing operetion of the switch, one of said relays being connected to said circuitsand arranged to tend -to move tosw itch clos-in '1 position during a'predetermined range-0 ihase difference between the electromotive orccs of the circuits including phase coin-' cidence and to move from switch closing position when the phase diit'ei'cnce is outside this range, means for delaying the operation of and relay whereby the relay-can reach switch closing position only when the d1flfer= ence between the frequencies otthe electromotwe forces 18 less than a predetermined value, and'another ofsaid relays being con.-

nected to said circuits and arranged to remain in switch closing position during a 'rzinge of phase difference beginning snbse quently to" the end of said first range of phaserdifi'erence and ending prior to phase I coincidence and then-to move quickly out of switch closing pos tion.

15. A synchronizing device comprising a movable circuit controlling member, means for exerting opposing torques on the member, means for retarding the movement of anzinduction d sk adapted to'be actuated 'in accordance with the sum of and difference between two electromotive forces contacts co'ntrollcdby said disks and means for re- .tarding the movement of one of said disks. In witness whereof, I have hereunto set my hand this 23d day of November, 1926.

' OLIVER. o. TRAVER.

plurality of cooperating relays, eac having the member 'to circuit controlling, position,

for exerting opposing