US1681158A

US1681158A - Automatic switching system

Info

Publication number: US1681158A
Authority: US
Publication date: 1928-08-21
Anticipated expiration: 1945-08-21

Description

Aug. 21, 1928. 1,681,158

A. E. ANDERSON AUTOMATIC SWITCHING SYSTEM Filed April 28, '1927 1 y J r 0 E $0 U) r .7 as 9 -53 L 14 ,0 H

Inventor:

A'P'vid EAnderson, y m

HIS Attorney.

Registered Aug. 21, 1928.

U NIT D ST ATE S series.

ARVID E. ANDERSON, or soo'rrA; NEW YORK, AssIGNoR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC SWITCHING SYSTEM.

. Application filed April 28,

My-invention relates to automatic switch. ing systems, and particularly to switching systems forselectively controlling the connections between a load circuit and two alterlatingcurrent sources and its object is toprovide an improved switching system of this particular kind.

In systems of distribution iii-which a load circuit is normally suppliedby a preferred source of current when the conditions of that source. are normal and an emergency source of current is':arranged .to' supply current to the loadcircuitwhen the preferred source fails, it isdesirable to reconnect the. preferred source,- when it is reenergizechfto the load circuit -befre' the emergency source is dis-- connected therefrom in orde'rthat the supply of currentto the load circuit may not be interruptedwhen-the transfer is made. .In accordance with one feature OfJmyinVentiOn I provide an arrangementwhereby the preferred source, when reenergized while the cmcrgency'source is supplying current to tho load circuit, is not reconnected to the loadv circuit until a predetermined phase'rclation occurs between thevoltages of the tw'o sources so that when the two sources are connected together an excessive circulating-current does not flow between the two sources. My invention will be better understood from the following description taken in conmotion with the accompanying drawing and its scope will pointed out in the appended claims. v

Referring to the accompanying drawing, which is a diagram of anautomatic switching system for selectively controlling the coir nections between aload circuit, a. preferred source of currentand an emergency source of current. 1 and 2-represents two sources of current. shown'as supply circuits, whichare adapted to be connected to a load circuit 3 by the circuit breakers 4 and 5 respectively which maybe o-fanysuitable type, examples of which are well known inthe art. As shown the circuit breakers 4 and 5 are ofthe well known latched-in type and are provided with the closing coils'G and 7 respectively andthe trip coils' S and 9 respectively.

10 and 11 are voltage relays which are adapted tobe energized from the preferred and the emergency sourcesrespectively. The voltage relay 10 has acontrol relay'12 associated therewith which is arranged to be en ergized when the voltage relay 10-i's ener 1927. Serial No. 187,402.

relay 11 is energized a predetermined amount. Y i

and thejvoltagerelay 10 is deenergized. The control relays'12 and 13 are preferably timedelay relays so that they do not function until after their coils have been energized acertain length Of time In-this manner momentary changes in thevoltagesof the sources do not effect unnecessary openings and closings of the circuit breakers.

In order that eithersource may be. employed as the'preferred source a change-over switch 15 is provided which isadapted-when moved to different positions .to' change the connections of the-various: control devices to accomplish this result. i lVhen .the changeover switch 15"is in. itsaleft -ha'nd position the source 2 is the preferred source and source 1 is the emergency source. and when; the change-over 15 is in its right-hand position the source 1 is the preferredsource and the source 2 is the emergency source. I 1

In order to effectthei closing of thecircuit breaker associated with the preferred source when it is reenergized,..-I provide an auto matic synchronizing. device--16jwhich is -arranged to operate to effect the closing of the preferred circuit.- breaken when i a. predetermined phase relation Occurs between the voltages of the two sources 1 and 2. Thislsynchronizing device may be of any. suitable type, examples of which are well known in the art. If the sources 1 and 2 are connected together at some other point so-that their frequencies arcthe same but the phases of their voltages at the points where they are connected to the load circuit. may differ from each other, itis preferable to have the syn-. chronizing. device 16 arranged so that it closes its cont-acts 17 only when. thephase difference remains less than acertain amount for more 'than .a predetermined length of'time. *If the sources 1 and 2 are independent sources so that they may differ in frequencies as well as phase-it is=preferable in that case to use a synchronizing device which also functions in accordance with the frequency difference. ---Such a device'is shown in Letters Patent-Reissue 16 ,540 to O. C. Travel. Since the'particular construction of' the synchronizing'device forms no part of my invention I have not shown the device in detail.

In order to effect the reclosing of the circuit breaker associated with the preferred source in case it is reenergized and the automatic synchronizingdeyice 16 fai ls to function within a predetermined time; provide a time relay 18 which is arranged to eflect first the opening of the circuit brc-akerj-iassociated" with the emergency source and then the closing of the circuit breaker associated with the preferred source. 7

19 and 20 are control -r'elays of'the well known 'hesitating type which control the circuits ofthe'clo'singcoils 6 and 7 respectively. 21 and'2 2- are control transformers which are connected respectively to the sources l and'2 and which supply current to the 'various con'=- trol dei icess Since "it is aisually desirabl *to} have'any ipping action due to over-current trans ferried-to the gene'rating' stationj breaker, the circuit-breakers 4 an'd"5 are preferably pro vided with over-current -protection which functions onlyiin ease of a'fvery severe oven load whichfw'arren-ts'thef lockingoutof the= circuit breakers. #I-n the 'drawing'f I-have shown-an oyerloadiela'y 23"which-i'sconnect ed to 'thelo'ad circuit'j3 by a currenttransformer 24i The overload rel'ay23 controls the circuit of alocli o'ut' relay 26which'1s arranged-in any suitable manner, examples-- of which are'wellknown' in the a'rt so that it remains inits energized position after its coil is deenergizeduntil it is reset by hand. The coil of the 1ock-out-re1ay '26 is arran ed to be connected inseri'es with the trip'cml 8 and contacts 27- of relay 23 if the circuit breaker 4is closedwben the overload relay 23 is operatedand to be connected inseries with the trip coil '9 and 'contacts'28 of relay 23 if thecircuit'breaker-5 is closed-when the overload relay 23'is operated. "The lock-out relay 26 when in its energized position-prevents the circuit of both closing coilsfrom being completed.-

The-operation 'ofthe system-shown is as follows :It' will be assumed-that the change over switch 15 is inits left-hand position, that both ofthe circuitbreakers 4 and -5 are open, and that both 'of the'sources 1 and 2 are ene rgized simultaneously. The relay 10- is connected across the secondary of the transformer 22'by contacts 33 and 34 of the changeover switch 15 so that the relay is. energized by the voltageof the preferred source 2-. By closing its contacts 35, the relay 1O completes the circu'itof the coilof the time-relay12- across the'secondary'of-the transformer 22 through contacts 33 and 34 of the change-over switch 15. The relay 11 is connected across the secondary'of the transformer 21 by con tacts 36 and 37 of tlie'change over switch so that the relay is ener zed by the emergency source-1. By closing-its contacts 38 the relay 11 closes contacts in the circuit of the timerelay 13 but the circuit of this time-relay is open at this time at the contacts 39. of the relay 10. Therefore only the time relay 12 is energized long enough to close its contacts when both sources aresimultaneously.enerr The coils 40 and 41 of the synchronizing device 16 are alsocpnnected across the secondaries of the

transformer

22 and 21 respectively by the contacts-33,34, and 36, 37 so that the synchronizing device is operative to close its contacts-17 'when-the -predetermined phase relation between-'thevoltages ofi-the two sourcesoccurs. '=Preferably'the time delay of the synchronizing device 16-=-is longer than, the time delay of relays 12 so'that it does not have time to close its; contacts 17' before the preferred circuit breaker is closed.

' After a predetermined'time,relay12-closes its contacts 42, there'byzcompleti ilga. circuit-y for the hesitating control relay 2O 1 to :efi'ect the completion of the circuit :0f:tl1'e=0l0sing,--'- coil 7;" Thecircuit of theicontro-laaelay20 is frombne side 'of a: suitable source-of con-- trol current through theaauxiliar-y; scontacts 43 on circuit breake'r5,1 coil 20, conductor. 44,; contacts 45 oflockout relay 26 conductor-.46,

auxiliary contacts 47 on circuit breaker 4,

condu'ctor48, contacts-49 and 50 of 'change.

over switch 15, conductor'51, contacts 42 of relay .12 to the other side of theI-eontrol source; The control relay- 2O3-by: closing its contacts 52 completes the circuit. of= the closing coil 7 so.thatthercircuit breaker 5 closes and connects the preferred source 2 to the load circuit a 1 w 1 It will now'be. assumed-that while the circuit breaker 5 'isclosedcandathe emergency. source 1 is ener ized the source 2 fails so that the voltage reliiy; 10 opens its contacts 35,

which causesthe time relay 12 to bedeenergized, and'closes-its contacts 39 so that the coil of the time-relay 13 is connected across the secondary of the transformer 21$ After the coil of the relay 13 has been energized for apredeterinined length of-ti'mc, the relay 13 closes its contacts 54-an'd completes a: circuit for the trip coil 9"so that the circuit breaker 5; opens and disconnects the source 2 from the loadcircuit 3'. The circuit of the'trip coil 9: is from one side ,of a suit-, able source of control/current through aux-- iliary contacts 55 on the'circuitbreaker 5,

trip coil 9, conductor 56, contacts; 57- and 58 As soon as the' 66 and'67 of change-over switch 15, conductor 59, contacts 54 of relay 13 to the other side of the source of control current. The relay 19 by closing its contacts 68 completes the circ'uit of the closing coil 6 so that the circuit breaker 4 closes and connects the source 1 to the load circuit 3.

It will be assumed now that while the emergency source 1 is supplying current to the load circuit 3 the ,voltage conditions of the preferred source are restored'to-normal control relay 20. I This circuit'is from one side of asuitable source of control current, through auxiliary contacts 43 'on the circuit breaker 5, coil ofrelay20, conductor,44, contacts 45 of lock-out-r'elay 26, conductor-'46,

contacts

69 and 70 of change-over switch 15, conductor 71, contacts 17 of synchronizing device 16, conductor 51, contacts 42' of relay 12 to the other side'of the control source, The energize tion of the 'hesit ating control relay2O effects the closing ofthe circuit breaker '5' inthe manner heretofore described. The preferred source'2the'refore is reconnected'to the load circuit 3 before the emergency sourcel is disconnected therefrom. When the circuit breaker 5 closes a circuit is completed for the trip coil 8 of thecircuit'bre'aker 4 to effect'the opening of this circuit breaker and the disconnection'of the emergency source 1 from the load circuit 3. The circuit of the trip 7 i coil 8 is from one side of a suitable source of control current through auxiliary contacts 72 on the circuit breaker 4, trip coil 8, con ductor 73, contacts 74 and 75 of. change-over switch 15, conductor .76, auxiliary contacts '77 on circuit breaker 4, conductor 78, auxiliary contacts 79 on circuit breaker 5, conductor 51, contacts 42 of relay 12 tothe other side of the control source.

If for any reason the desired phase relation between the voltages of the two sources does not occur within a predetermined time after the preferred source is reenergized the time relay 18, which has a'relatively long time delay, operates to effect the opening of the circuit breaker associated with the emergency source and the subsequent closing of the circuit breaker associated with the pre ferred source. The circuit of the time-relay 18 is completed when the preferred circuit breaker is open and the contacts 80 ofthe relay 12 are closed; This circuit is from one side of a suitable source of control current through auxiliary'contacts 43 on the circuit breaker 5, conductor 81, contacts 82 and 83 of change-over switch 15, conductor-'84, coil of relay 18, contact 80 of relay 12-to the other side of the control source; Relay 18'by closing its contacts 85 completes a circuit for the trip coil 8 ofthe circuit breaker4 to effect the opening of the circuitbreaker. Thisci'r cuit isfrom one side of a suitable source of control current-through auxiliary contacts 72 oncircuit breaker 4, trip coil 8, conductor 73, contacts 74'and (.5 of change-over switch 15, conductor 76, contacts 85 of relay-'18, con

ductor 51, contacts 42of relay 12 to the other side of the control source. Thecircu-it breaker 4 by closing its contacts 47 whenit opens completes the heretofore described circuit for the hesitating control relay 20 to'effec'tf the closing of the circuit breaker 5. I

' If the circuit breaker 4 should be closed at any time when the emergency source1is-de energized and the preferred source'2 isenejr' gized'a circuit is completed forthe-tripcoil 8 as soon as the relay "12 closes its contacts-'42.

This circuit is from one side of-a suitable,

source of control current through auxiliary cont-acts 72 on circuit breaker 4-,"tri'p-coil 8.,

conductor 73, c ontacts.74"and 75' o"f'change.

over switch 15, conductor76, conta'cts'86fof voltage relay'll conductor 5 1,"c ontacts"42 of; relay 12to' the other side of'the control source.

The closing of the circuitbreaker then effected'by the relay 20the circuit of which is completed by the circuit breaker 4closi'ni its auxiliary contacts 47 as heretofore des'cri ed, If at any time an excessive overload'occllrs on the load circuit3so'. that the overload relay 23 is'sufiiciently energized'to close its contacts 27 and 28, a circuit is completed'for the trip 1 coil of whichever circuit breaker is closed and the coil of thelockout relay 2 6. Thelockout relay 26 by opening its

contacts

45 and 62 prevents anyifurther automatic closing of thecircuit breakers until the relay 26 isreset by hand.

If it is desired to have the source 1 as the preferred source, thechange-over switch 15 is placed in its right-hand position. The

voltage relaylt) and its associate time-relay 12 are then connected'across the secondary of the transformer 21 by contacts'36 and 87 of the change-over switch and the voltage relay 11 and its. associate time-relay 13 are connected across the secondary of the" transformer 22 by contacts 33 and 3701'. the change- I over switch. The conductor 59 is connected to the conductors 73 and 48 by contacts58 and 88 and contacts 67 and 49 respectively of the change-over switch so that time-relay 13 controls the circuit of thejtrip coil 8 of the circuit breaker 4 associated with the source 1 which is now the preferred source and the circuit of the'hesitating control relay 20 of the emergency circuit breaker 5. The conductor 71 is connected to conductor 63 by contacts and 90 of the change-over switch s o that synv chronizing relay 16 controls the vcircuit ofhesitating control rela 19 associated with the preferred source 1. he conductor 76 is con-i nected to the conductor 5 6,by contacts and 91 of the change-over switch so that trip coil 9 associated with the emergency breaker 5jis. controlled by the time-relay 18 and the voltage relay l1, and the conductor 84 isconnected to the auxiliarycontacts 60 on the circuit breaker 4 by. contacts 83-,and 92onthe change-over switch so that the time-relay 18 is, energized whenever the preferred circuit breakerd'is openand the contacts of the time-relay 12 are closed( Since the operation of the system when the change-over switch. 15 is its, right hand position is similar; to the, heretofore described operation when it isin its l eft= hand p ositi0iL itwill be obyious one skilledin the art and therefore it is believed that a, detail descripr tionis finnQCQSSflry y;

Whilelhav.e in acco glan'cewith the Patent I Statutes shown and described. my im-"en'tion asiapplied to a particular'system and as em1 bodyzing various devices diagrannnatically indicated, changes and modifications will be ob -i vious tothose skilled in the art, and therefore aim in the appended claims to co yer all such changes and modifications as fall within tlietrue spirit andscope of my inventions, I

W11at I claim, as new and I desire to se m e by Letters Patentpf the United States,l;i s 1. In combination-,a load circuit, a sourcel of: current connected thereto, another source i of current normally disconnected from.,sa i d load circuit, means responsive r0 21 redete'r; mined abnormal conditionlof said first mentioned source for effecting .the' disconnection thereof from said load circuit and thecoi nec tion of said other source to said load circuit,

and means responsire to predetermined ,phase relation between the voltages of sa d sources when, said other source is connccted to said load circuit for effecting the reconnection of saidfirst mentioned sourceto said load circuit. I I i I 94.3111 combination, a load circuit, afsource of current connected thereto, another SQurco of current-normally disconnected from said load-circuit, means responsive to reader-1, mined abnormal condition of said first men tioned source for effecting the disconnection thereof from saidload circuit and the connection of said other source to saidioad circuit, and means responsive ,tQ a predetermined phase relation between thewioltage of said sources when said other source is connected to I said load circuit for effecting:t-hejreconnection of said first mentioned sourceto said load circuit an'd the subsequent disconnection of the other source from said load circuit.

3. In combination, a load circuit, a p'r etea e158 dition of said preferred source for effecting the opening of said firstmentioned switching means, means responsive to the openlng of saidfii'st mentioned switching means for efl'ectingthe closing ofsaid second switching means, and means responsive to apredetermined phase relation het-ween the voltages of said sources when said second switching means is closed and both ofsaid sources are energized for reclosingsa d first mentioned switching means,

. In combination," ioadscircuit a preg ferred sourceof cu rrent,-sw 1tch1ng means for connecting s -aid preferredsource. to said load circuit, an. emergency source of, current, a secQnd switching means for Y connecting said emerge cy and. to said ,1oad;cir.cuit,jme s responsive to a predetermined abnormal voltage condition of said preferred source when the voltage cond tions, of.,sa1 d emergency,

source are-normal for effejctingithe opening of said first mentioned,Iswitching means and the closing of; said sec switching means,

and, means responsiyejo a predetermined phase reiation between the vnl'tages of said sourCcS ,whensaid second switching means s 2 closed and" bothiof said sources are energized for I reclosin'gl said fir, mentioned swit'cl in-g, means and for effecting. the subsequentopening ofsaid'second switching means' 5 lIn combination, a load circuit, a vpreferred-source'of current, switching means for connectingsaid prefe'rredsource; to said load circuit,- anemergency; source of current, a second switching: means for connecting said emergency sourgmto said load circuit, means responsive toa predetermined abnormal 'voltage conditioin of said preferred source when the voltage. conditions of 7 said I emergency source are normal foreile cting the opening of said firstzmentioncd switching means, means responsive to the 'opening'of said first mentioned,switching me'ans for eifectingthe c losing offs-aid second switching means, means repensive to a' predetermincd phase relation between the ,ibltzigw of said I sources when said second switching inc-ans is closed fo'r reclosing saidfirst mentioned sn-"itchin'g' means, and means'rcsponsire to thcreclosing of said first mentionedswitching means for effecting the opening of the second switching means.

G. In combination,aloadcircuit, a sourceof current connected thereto, another source of current normally disconnectedfrom said load'circuit, means responsive to a predeter mined abnormal roltage condition of said first mentioned source. for effecting the disconneetion'thereof from said load circuit and the connectionofsaid other source to said load circuit, synchronizing means responsive to a predetermined phase relation between the voltages of said sources after the voltage conditions of said first mentioned source are restored to normal for effecting the reconnection of said first mentioned source to said load circuit, and means for effecting the disconnection of said other source from said load cir cuit and the subsequent reconnection of said first mentioned source to said load circuit when said synchronizing means fails to effect the reconnection of said first mentioned source within a predetermined time after the voltage conditions thereof are restored to normal.

7. In combination, a load circuit, a source of current connected thereto, another source of current normally disconnected from said load circuit, means responsive to a predetermined abnormal voltage condition of said first mentioned source for effecting the disconnection t-hereof from said load circuit and the connection of said other source to said load circuit, synchronizing means responsive to a predetermined phase relation between the voltages of said sources after the voltage conditions of said first mentioned source are restored to normal for effecting the reconnection of said first mentioned source to said load circuit and the subsequent disconnection of said other source from said load circuit,

and means for effecting the disconnection of said other source from said load circuit and the subsequent reconnection of said first mentioned source to said load circuit when said synchronizing means fails to effect the reconnection of said first mentioned source within a predetermined time after the voltage conditions thereof are restored to normal.

8. In combination, a load circuit, a source of current connected thereto, another source of current normally disconnected from said load circuit, means responsive to a predetermined abnormal voltage condition of said first mentioned source for effecting the disconnection thereof from said load circuit and theconnection of said other source to said load circuit, synchronizing means responsive to a predetermined phase relation between the voltages of said sources after the voltage conditions of said first mentioned source are restored to normal for effecting the reconnection of said first mentioned source to said load circuit, and means for effecting the disconnection of said other source from said load circuit and the subsequent reconnection of said first mentioned source to said load circuit when the voltage condition of said other source becomes abnormal while supplying current to said load circuitand the voltage conditions of said first mentioned source are subsequently restored to normal.

9. In combination, a load circuit, a source of current connected thereto, another source of current normally disconnected from said load circuit, means responsive to a predetermined abnormal voltage condition of said first mentioned source for effecting the disconnection thereof from said load circuit, synchronizing means responsive to a predetermined phase relation between the voltages of said sources after the voltage conditions of said first mentioned source are restored to normal for effecting the reconnection of said first mentioned source to said load circuit and the subsequent disconnection of said other source from said load circuit, and means for effecting the disconnection of said other source from said load circuit and the subsequent reconnection of said first mentioned source to said load circuit when the voltage conditions of said other source become abnormal while supplying current to said load circuit and the yoltage conditions of said first mentioned source are subsequently restored to normal.

10. In combination, a load circuit, a plurality of sources of current adapted to supply current to said circuit, means for selecting different sources as the preferred source, means responsive to a predetermined abnormal condition of the selected source for effecting the disconnection thereof from the said load circuit when it is being supplied thereby and the connection of another of said sources to said load circuit, and means responsive to a predetermined phase relation between the voltages of said selected source and said other source when said other source is connected to said load circuit for effecting the reconnection of said first-mentioned source to said load circuit.

11. In combination, a load circuit, two sources of current for said load circuit, means for selecting either of said sources as the preferred source, voltage responsive means controlled by said selecting means so that it is responsive to which ever source is the preferred source, means controlled by said voltage responsive means for effectin the disconnection of the preferred source from the load circuit and the connection of said other source to said load circuit when said preferred source is supplying current to said load circuit and a predetermined abnormal voltage condition occurs on said preferred source, and means responsive to a predetermined phase relation between the voltages of said sources when said other source is connected to said load circuit for effecting the reconnection of said first-mentioned source to said load circuit and the subsequent disconnection of said other source from said load circuit.

In witness whereof, I have hereunto set my hand this 27th day of April, 1927.

ARVID E. ANDERSON.