US2047842A - Circuit breaker - Google Patents

Description

July 14, 1936. L, s WALLE 2,047,842

CIRCUIT` BREAKER Filed Apri1`25, .1933

'A2 sheets-sheet 1 Im/efor' v Ludwig .5.. Walle by,

His Afforvneg July 14, 1936.k

L. s. wA-ITLE v CIRCUIT BREAKER Filed April 25, 1955 2 sheets-sheet' 2, l v

Inventor:

ig 5. Walle,-k

ww r `oA fm A. w d H u .L

Jay'

STATES VLlulv'rig Si Walletv Lansdowne, Pa., a'ssignor to General` Electric Campani a corporation-of .New York v.

Y Application April z5. 193s. Aserian Na 667,856 a 4013111.15'(cLzo-'lleo'A n j -My invention relates to circuit breakers, more particularly to circuit breakersof the type known *jas branch-circuitclrcuit breakers which provide the protective features characteristic of a fuse aswell as the additional advantages of. amanually v 1, operated switch, ,and'has for any object the profvision oi' a simple, reliable and inexpensive circuit breakerof this-character. lo; f-'; Heretofore, branchy circuit breakers have been -provided with a thermal release arranged to trip "time circuit breaker liponltheoccurrence of4 an overload. and with a. manually operable handleV Fior opening .and closing the circuit independently ofk the thermal release.` However. muchl isffyet to vbedesired in such circuit 'breakers [hitherto proposed to replace fuses because-oi ofthe, fact that the arc has been extinguished by ymeans of magnetic 4blowouts and the .like

withresulting llame and 'arc gases. Inas'much' as branch circuit breakers-as applied to panel? y boards ion the protection o f lighting/circuits,

are called upon yto interr.upt'currentsoi.' :very

considerable magnitude,v as high as 5,000y amperes orsmore, 'when the breaker carries out the .short acircuit protective 'functions oi a fuse,` git'will rbel'appar'ent that a considerable 'quantity of arc gases "are-generatednand that 1 the flame voi-the is quite appreciable; thesetwo features be# T ingfundesirable for circuit breakers for housevrho'ld Furthermore; since the fuses which v have hithertobeen usedaccomplish thisy inter-- built up the resistance becomes so great that the arc can no longer exist, and it is extinguished.

For' a more complete understanding of my ing vention, reference should now be hadto the accompanying -drawings wherein I Vhave shown diagrammatically, in Fig. 1 aside view partly in section of a circuit breaker embodying my invention; Fig. 2 shdws the parts of the circuit breaker o1' Fig. l'just before the-contacts are closed, while Figs. 3, 4, 5and 6 illustrate an improved form o f a' circuit breaker embodying my invention.-

, Referring now to Fig. 1', I have shown my invention inv one formas applied to a branch-circuit-breaker suitable' for lighting circuits indicated `by the conductors Illv and I I. The circuit 15 breaker, mounted on an insulating base I2,v comprises-a frame' I3 for thejoperating mechanism, 'a b imetallic thermal element .Il and an arc in-n i terrupter I5. 'I he frame IJjhas anupturned end I8 from which ispivotallysupported at I1 an 201 l 22 provided in a pair Vof parallel L-shaped links 26 25 y l between which the, member .I lmoves. One pair of adjacent ends 29 of the parallel links 26 are p'ivotally secured at 30 to the movable,'conta'ctinemberv `II of the arc interrupter I5. Iheother ends 3l of 'the links ze areprovided witnprojecuons u which so I are engagediby adjacentvends of a pair of springs l ",ruptlon-iof -the circuit withoutspurts of llamen I1 which embrace the -links 20. The other ends jand'withoutfloud popping accompanying the vin'- terruptionf of anoverload current oi high magni- 35'f ,tudv

n In carrying out my invention a satisfactory circuit )breaker should theseadvantages.

`ln-one io'rm therefof,y `I provides. circuit breaker `which is capable -of tween' the separating contacts. the gas pressure f within the chamber Increases quite rapidly.' ^'l-his may bec! the lorder of 1000 pounds per square inch. Theresistanceof thearc' increases :rapidly with pressure 'so that vas the pressurcis ot the springs are s ecured to. inwardly projectv ving ends 38 of the frame I3.' It will be observed that the circuit represented by the conductors LIII 35 4 and I I may be traced fromh conductors I I through the branch 'circuit breaker by conductor I0, thermal' element Il; flexible conductor I2, movable contact member 3I, 4 stationary v contact member 4t provided in the arc interrupter or compres- 4o sion chamber I l and by conductor M tothe; 4- "conductor III.` Thcontact'members 3l and are' constructed oran arc resistant material, for

sistantmaterials may ofcourse be used.

The operating mechanismof 'the-branch circuit breaker is trip free; that is to say, the operating handle; II, even though operated, cannot example, in theoperation'oimy invention it -willbe 'observed' that thefcircuitbreake is normally closed after Ait has opened in response `to ya ent, the parts then being in the relativepositions shown Fig. 1., by 55 predetermined maximum' 4:I

example y,silver molybdenum, but other` arc rrcmaintain' a closed circuit 1f ar current 'exists orf suilicient magnitude to' open the" breaker. For 5omoving the operating handle III to the right, whereby the operating member I3 is rotated in a clockwise directionfaround its pivot I1 to bring its projection 2| into engagement with the notch 22 in the links 26 and thus move the links 26 a slight amount in a clockwise direction and also bodily downwardly. When the handle I9 strikes the end of the frame 33 the movable 'parts are in the positions shown in Fig. 2. A projection 48 extending from the links 26 is moved from the position shown in Fig. 1 downwardly beneath a latch4 49 carried by the thermal element I4. The latch may of course be operated by means other than a thermal element. Atthis time the movable contact 3| has not engaged thestationary contact 43 to close the circuit. As soon, however, as the operating handle I9 is released the springs 31 rotate the links 26 about the projection 48 to operate the movable contact 3l into engagement with the contact'43 with a snap action, thus closing a circuit through the breaker. The springs 31 expend only a part of their energy in operating the contact 3| to the closed position. The remaining energy isat all times available for operating with a snap action the contact 3| to the open circuit positionA in response to overload or short circuit current.y The. floating links 26. in the final or closed circuit position are vfree of the operating handle. The links 26 as they freel themselves from the handle I! impart to the handle through the projection 2| an impulse which returns the handle towards thev oi position. As shownl in Fig. 1, the handle is retained in an intermediate position by the engagementA of the end 20 of the handle with the leaf spring carriedon the frame. By moving the handle I9 'from ythis intermediate position vin a counterclockwise dlrectiomas viewed in Figs. 1 and 2', a

projection |3a carried by the operating member I3 Voperatively engages the thermal element I4 to move it to release vthe latching projection 48.

'I'he springs 31 thereupon operate the movable contact 3|- with,a snap action to the open circuit position.

Assuming now that an overload occurs on the circuit represented by the conductors Il and II,

the thermal element I4 is ilexedin a clockwise `direction to release the latching member 4 3 from the latching projection 43. vThe springs 31$there upon cause the movable contact 3| to move toward the right as viewed in Fig. 1 with a snap action to the open circuit position shown in Fig. 1. As the movable contact 3l leaves the stationary contact 43, an arc is drawn between them. The arc interrupter I5 comprises a steel cylinder 53 within which a pair of kerosene-free ilber bushings 5I and 52 extend. I have found that .kero.

sene-iree ber or an equivalent material is es. fsential to the operation of my invention and deem its use in the arc chamber an important part of my invention. The steel or metallic cylinde'rand the insulating members are so arranged as to provide a sealed chamber of relatively small volume, such that the arc causes a rapid increase in air pressure in the chamber, the high air pres# sure exerting an-"opening force on the movable contact. This increase in pressure is due to the.

heating by the high temperature of the arc of the air within the chamber. The rise in pressure may be further accentuated by the heating of other gaseous fluids produced by the action of the arc on Ithe air and the materials-within the In order to produce a strong and rigid 'construction of thev arc chamber, the bushings gli and 52 are inserted into the ends of the steel cylinder.

forming a. part of the conductor '44. The insulating bushing 5I permits a reciprocal longitudinal movement of the movable contact member 3|,

one end of which is always locatedin the chamber and the other end of which is always located outside of the chamber. 1

A leather sealing washer is provided around l5 the movable contact member 3 I, the washer being provided with an inwardly projecting cylindrical extension 66. Since a certain amount of metal vapor is produced when the Acircuit breaker ipterrupts a current of large magnitude, it is neces- 20 sary to prevent this metal vapor from collecting on the movable contact member. 3| where it may harden and interfere with successive operations of the circuit breaker. The leather washer with its inwardly iextending projection tends topre- 25 vent this'collection of the metallic vapor because of its wiping action on the movable contact mem.- ber 3| and furthermore assists in maintaining a substantially air-tight connection around the movable contact member `3| by its cooperation 80 with the contact member and the lwalls of the chamber. yAt the same timey the leather washer provides forsnap movement of the movableccn.- tact by the spring means by 'offering only relatively slight friction to such movement. g5

I have stated, when aliA arc isdrawn between the contacts 3| and 4 3, the air pressure within .the chamber of the'arc interrupter in-` creases rapidly. The'potential drop across the f proximately proportional to the in rse square i root of the current. This characteristic oi' the arc,-in, addition to the rise inpressure in the chamber, causes a quick interruption ofthe circuit. Furthermore, since the rise in pressure' def pends upon the magnitude of the current inter' rupted, it will be seen that the greater the'over- 4load current thel more quicklyl will the pressure rise to a point where the arc resistance.be comes so great that the arc can v.no longer Obviously, the pressure within the chamber also exerts an opening force on theV movable contact accelerating its speed of opening in proportion to the degree of pressure built up by the heat of the arc.

Of course, it will be understood that in order to reclose the circuit breaker it is only. necessary to .Il

repeat the operations described in connectionl with Figs. 1 and 2.

Referring now to Figs. 3, 4', 5 and 6, I have shown what is believed at the present time to be'V the'best form of an operating mechanism. This II particular operating mechanism forms no part of my present invention, and it is described and claimed in a copending application Serial No. 667 ,855, riled April 25, 1933, Atwood, entitled Circuit breaker and assigned to the same assignee 76 as the present invention.

A base Il formedof molded insulation provides a. support for the operating mechanism as wellasV for the arc interrupter I5. -Theuar'c interrupter or compression chamber-I5 is within au15 enclosure u molded intensity with 'me The stationary contact 4 3 is providedwith screw threads 6I engaginga-'threaded aperturein l shaped conductor M, `the rinner threaded end 'Il fofwhich is located within the molded enclosure :n.the other end of the conductor u' extending ythrough aslotllto form a terminal. 'Ille movy Y able contact member '3i is mounted for reciprocal longitudinai movement into and out oi.'- cngage 10` mentwith thelstationary'contact 4l'. kA wiisher f llof leather or other suitable materialjisplaced y,between the bushing" II and aclosuremember Il Y -"jprovided with a ilange l1 arranged to'v enkele the notched end Il of the insulating enclosure Il.

at -'molded integrally with the encloaure'll.' The frame. .Il is secured by screws Il extending through the base l0 in a position suchthat the `rame, therefore. performs thedouble "function 'Y' f maintaining the closure` in place and sup? the operating mechanism.

@ The reclprocal'vertical movementl ot con-'V member 3| is obtained yby means of a pair of f yover-center springs 08, which springs have their corresponding upper ends I0 carried by .projections IIII secured on opposite sides of the operatinghandle IIII. The opposite ends of the springs "98j are secured 'to a pin |02 extending through an aperture in the movablecontact 3l near its outer end. The operating handle `IM is secured toan -f i'nvertcd U-shaped operating member Iiaswhich in turn has its legs mounted on a pivotpin I 49 carried by the 'upper ends of the arms vof the ilshaped support 09. When the operating handle is moved from vits left-hand position, shown in Flg`. 3, to its right-hand position, shown in Fig. 4,

u the movable contact II is moved lto and from its [reciprocal vertical movement ot the movable con;

osed circuit position with aI snap `action. The

taci; li isinsured by member I04a,comprising `r'two parallel legs connectedy together' by a midportion 1Mb. The upper endsot the legs mounted on the pivot pin I, while their lower ends-are'pivotally securedto the pin IGZ.

vertical ydirection to ment-oi the pin I0 2 caseot overload, abimetallic thermal element /Ill which is iJ-shaped as shown in Flg.'6 and connected in) circuit with the switch contacts soas to be heated bythe current passingthrough thebreaker. -is caused to iiex away irom a latch pivot pin lu. 'rm-, memberl la has s non m yinto` which extends a'rodfl I2 into abutting relation with the member I Il. A compression' spring :engaging a stop memberfiltzsecured tothe extensions!! rof the frame vll,\ vhile the other end is emma base Il.

The operating mechanism is supportedirom the I1 by means of a Ufshapedifframe Il.' yExtend-- at right angles irom'the `upper ends'oi the,

portion Il. of the frame abuts the .closure member le and maintains it securely in place. .The

.Since the lower end` ot the member Illa lnovcsv in acurved path about the pivot |04, the openingv yinthe movablecontact member II through which 'thej pin It! extends is elongated in a vertical ydire'ction, i..e., inthe directions!v the'pivot pinA I Il, so that sui'iicient lost motion is obtained in a provide for-freedom oi' move'- AvIll rto permit a quick opening of the circuit. It4 [will be observed thatthe latch I lssuDDOrted by aftripping'member I II which is mounted on the I i iitfe'icircles the rodandhas one end normally u engagea member Iiisecured'to the ill.L The tripping' spring I'II is shown co as shown inFig.'5. As soon as the thermal element IIII releases thetlatching member I", it will be observed that .the `torce exerted by the trippingspring IIB is applied to the memberv III at [the notch III. Thisioroe urges the tripping A member-I I I in a clockwise directionaround its :splint Hl. l The end Ioi^the tripping member I'III engages the connection IMb ofthe member Illa which it be remembered 4is lconnected to the movable contact 3|.. 'The spring IIU inKV rotating the member IIII in a clockwise direction thus quickly operates the contact II to itsjopen' circuit position as shown in Fig. 4.l A projection I I'lafoi the tripping member III isl located lust below the extensions IIIb end IOIc extending from the operating handle IBI'. An opening ISI is provided in 'the extension IOIc`. The relative movement of the tripping member IIII 'from the 20 positdon shown in'Fig.- 3 tothe position shown in Fig. 4 brings asuitably colored portion on the extension I IOa into registering relation with the opening III so that an indication is givenl that the circuit bre tion.

been opened. by overload as Just described, the handle IIIr is first movedy in a counter-clockwise 1 extension .III formed integrally Awith the operatingmember IIIIa strikes 'a projection I2on the tripping member IIIv and :thereby rotates the tripping member in a counter-clockwise direc-l position as shown iny Fig, 3. 'Ihe switch closing operation isv then completed by operating the handle I 'in a clockwise direction to the posi-l tion shown in Figf., A second projection' I21 iormsdon the operating member IIIIa strikes the frame Il at the point indicated by the reference numeral Ill and acts aa a stop forthe'operating member. Y While I have shown a particular embodiment `oi' my invention, it will be'understood, of course, that Ido not wish to belimited thereto since many modincations may be made, and I..there fore. contemplate by the appended claims* to cover-any such modiiications as fall within the true spirit and scope of my invention.

' What I claim-as new and 4desire to secure by Letters Patent of the'United States, lszf 1 Ain electric circuit breaker for interrupting.

currents ot 5,000 amperes at lighting circuitvolt'- bushing secured to each forming therewith agas tight' circuit interrupting chamber, a stationary contact member extendingv through one oi' said bushings into said chamber, a coacting movable contact member 60 guided for `reciprocal Ilongitudinal movement within the other of said-bushings into -andout of contact with said'stationary contact member,

a packing gland-includlnga fibrous member co:

actingwith Ssaid last named bush movable contact to seal said interrupting chamber around said movable contact member against the escapeoi' gas athlghpressures during circuit interruption, 'said chamber having a relatively small volume'such that the air entrapped atlatd'o mospheric pressures in said chamber is heated by the arei formed upon separation oi-said contact j members to generate high gas pressures on'the order of 1.000 pounds per squarerinch, whereby currents ot 5.000'amperes at lighting circuit volt-' Y75 Vpressed lnFig. 33nd 5; with the contacts 010566. i

aker hasbeen tripped to its o pen posi' lili In order close the circuit breaker after it has direction from the position shown in Fig. 4. An

non until the latch los is again' in' the latcned 3 5 v ages comprising a metallic cylinder, an insulating 55 end oi' said cylinder and ing and, said 4 ages may be-interrupted without burning of .said contact members.

2. A circuit breaker for interrupting currents of 5,000 amperes or more at lighting circuit voltages comprising walls of pressureresistant material forming a gas tight compression chamber, a stationary contact and a movable contact in `said chamber. snap action operating means for said movable contact on the exterior of =said chamber, said walls defining a chamber having'a relatively small volume such thatthe air entrapped at atmospheric pressure in said chamber is heatedfby the arc formed upon separation of said contacts to generate high gas pressures on the order of 1,000 pounds per square inch, whereby said breaker is capable of interrupting cur-i rents of 5,000 amperes at lighting circuit voltages without detrimental burning of said contacts.

3. A circuit breaker for interrupting currents of 5,000 amperes at lighting circuitvoltages comprising a metallic cylinder, an insulating bushing mounted in each end of said cylinder, an annularl ilange on each end oi said cylinder ensgagingthe peripheryA of. the corresponding bushing, each of said flanges being swaged over the periphery of its bushing to form gas tightseais between said cylinder and said bushings and thereby forming with said cylinder a gas tight circuit. interrupting chamber, a stationary contact member ex Atending centrally through one of said bushings into said chamber, a coacting movable contact member mounted in the other oi' said bushings for reciprocal .longitudinal movement, vsaid. cylinder and said bushings defining a chamber having a relatively small volume such thatvthe air y,

entrapped at atmospheric pressure in said chamber is heated bythe arc formed upon separation of said contacts to generate high gas pressures of 1,000 pounds per square inch or more, whereby said breaker is capable of interrupting currents oi 5,000 amperes or more at lighting circuit voltages without detrimentalburning of said contact members.

'4. A circuit breaker for interrupting currents of 5,000 amperes or more at lighting circuit voltages comprising a metallic cylinder, a bushing made oi insulating material mounted at each end of said cylinder and forming therewith a circuit -interrupting chamber, a stationary contact memmovable contact member mounted in the other of said bushings and guided thereby for longitudinal movement, said bushings having relatively narrow peripheral portions tightly engaging the end walls of said lcylinder, sealing means between said movable contact member -and its guiding bushing -for substantially precluding the escape o! gas at high pressure fromsaid chamber during circuit interruption; said cylinder and said bush-v ings denning a chamber having a relatively'small volume such thatthe air entrapped yat 'atmos- -pheric pressure in said chamber is heated by the arc formed-upon separation of said contacts to generate high gas pressures of .1,000 pounds per square inch or more, whereby said breaker is a capable of interrupting currents' of 5,000 amperes or more at lighting circuit voltagesv without detrimental burning of said contact members.

ber mounted on one of said bushings, a coacting LUDWIG s. wams. as

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