US1910714A - Circuit-breaker - Google Patents

Description

May 23, 1933. L Q REED 1,910,714

CIRCUIT BREAKER Filed March 20, 1930 2 Sheets-Sheet l E k NN w jmdn C". Feeal.

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H T TOR/VE Y Si, '11 lA/VENTO?? 2 Sheets-Sheet 2 L. c. REED C IRCUIT BREKER Filed March 2o, 195o May 23, 1933.

R.. Y ma E MM M O ma n n m /d O \\\Nm L\\\\\ Patented May 23, 1933 UNITED STATES LYMAN C. REED, 0F NEN ORLEANS, LOUISXANA CIRCUIT-BREAKER Application fried March 20, 1930.

This invention relates generally to apparatus for interrupting and protecting electriccirouits and, more particularly, to certain new and useful improvements in such apparatus of the type known as circuit-breakers.

Heretofore, so far as I am aware, circuitbreakers employed for the purpose of protecting electrical systems against so-called overload and short-circuit conditions have been actuated bya spring operated mechanism which has a lixed time interval of circuitopening response to such overload or shortcircuit condition, such time interval being dependent wholly upon the strength of the spring and the weight of the parts moved thereby. In such cases, the flow of sliertcircuit current may often attain a magnitude approximately equal to the capacity of the system in which the short occurs and frequently causes the destruction of the circuitbrealier or some part thereof before the current-flow in the circuit is ruptured, T he losttime occasioned by such fixed time-interval of rupture of the circuit is exceedingly important on overloads of the magnitude of short-circuits, not only because the heating of the separable contacts of the breaker is unnecessarily prolonged, but because the shortcircuit current has the opportunity of growth to many times it would have if interrupted in a time-interval having a variable relation to the strength of initial current Aliow caused by the short-circuit.

However, even if the contacts be separated in such a current-responsive manner, opportunity may yet exist for growth of currentflow, due to the current-carrying capabilities of the occurring arc and the ionized air created thereby. And if a solid body of insulation material be interposed between the contacts for rupturing the are, surface leakage around such body may occur tending to delay the actual rupture of the current-flow. Many auxiliary devices have been proposed for breaking the arcl occurring on separation of the contacts, such as blow-out coils, dc-ioniaing plate assemblies, high-pressure-iniected air, quenching liquids, and the lilre. uch agencies require an operating tinie-intervil which is of appreciable magnitude compared Serial No. 437,514-,

with the circuit-rupturing time-interval that may be employed without creating dangerous conditions in the circuit, and hence do not wholly suiiice at all times to prevent serious I disturbances in the line on occasion of heavy short circuits.

My present invention has hence for its objects the provision of an efficient circuitbreaking or interrupting apparatus for both A. C. and D. C. systems adapted for the solution of the various problems stated and the accomplishment in approximately the lowest possible time of the results sought.

And with the above and other objects in view, my invention resides in the novel features of form, construction, arrangement, and combination of parts hereinafter described and pointed out in the claims. 1

in the accompanyingdrawings (2Sheets) Figure l. is a side elevational view of a circuit-breaking apparatus of my invention, shown in circuit-opening position;

Figure 2 is a sectional view of the apparatus taken approximately along the line 2 2, Figure l; 75

Figure 3 is view of the apparatus similar 'to Figure i, the several parts thereof, however, being shown in circuit-closing position, portions thereof being broken away and intermediate positions of some of the other parts being shown by dot-dash lines; and

Figure l is a view of the apparatus partly in plan and partly in section on approximately the line il-4, Figure 3.

Referring now more in detail and by reference characters to the drawings, which illustrate a preferred embodiment of my invention, the circuit-breaker proper includes spaced front and baclr walls l, 2, respectivelyA of suitable contour and preferably constructed of insulation material. Disposed transversely of the walls 1, 2, is a longitudinal partition A which includes a pair of overlapping slidable doors or engaging shutters 8, which, when closed, form an imperforate part of said partition for ldividing the space between the walls l, 2, into adjoining contact-eh ambers 4, 5, but which when opened provide an aperture communicating said chambers '-l, 5, as soon appearing.

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The shutters 3 are reciprocable in opposingly spaced jambs 6 also forming part of the partition A, each jamb 6 being provided with a shutter-receivin chamber 7 having one side wall extended beyond the other toward the short wall of the opposite chamber 7 of the other jamb. The overla ping margins ofthe lutters are provide with openmgs or notches 8 each registrable in reversed relation with the other, so that, when the shutters 3 are opened, the bottom walls 9 of the notches 8 overtravel each other in the space between the jambs 6 to align the openings 8 for admitting through the so formed aperture the opposing engageable ends 10 of a pair of ico-operable contact-members 11 of wysnitabie conducting material (Figure 4).

Each member Il i8 laterally presented perpendicularly tothe axis of a swingable subetantially U-shaped oontact-carrier 12 also of any suitable conducting material, the carriers 12 being oppositely pivoted for swinging their Carried contacts 11 in inverted arcs which together orm'a reverse curve, along which the engageable ends 10 travel in op- Sed directions into and out of engagement gdr respectively closing and opening the circuit.

The legs of each member 12 terminate in oppositety resented axially aligned ,ears or pivot members 13 ewise presented for standing in and rod: ly en aging aligned grooves 14 formed in the for d ends 15 of a horizontal supporting terminal member 16 also of conducting material. Each terminal member 16 is .disposed preferably parallel with, but transversely and laterally spaced from the other and is suitably supported on, and with its end 15 projecting over the side of, one of a pair of diagonal y spaced preferably rectangular insulation locks 17, each fixed between .the Walls 1, 2, at opposite ends ni .the respective contact-chambers 4, 5.

pin 1B is presented from a side of each block 17 in the plane of swingable actuation of the respective member 12 but oppositely the pivotal ax thereof; and attached at all md to the Pin 18, is a suitably elongated coil spring or-tensionally yieldable memhr 1.9 having its other end 'stretched past Said pivotal axis and secured to a pin 20 fixed t0 and between the legs ofthe member 12 ad- Vinfront its upperend. The spring 19 is reused, on actuation of .the member 12, to

ke POSD!! alternately on opposite sides 0f the pivotal axis thereof. So arranged, the respective springs 19 and associated swingable members 12 co4) ratively constitute a pair of toggles, whic when knuckled toward each other, act lor function to engage the contacts 11 in circuit-closing position,

as best seen in Figure 4.

n ineircuit-closing position, each shutter 3 is disposed with its inner notched end guidingly engaged between the imperforate portion of the other shutter 3 and the margin of the adjacent long wall of the respect-ive chamber 7. However, when the shutters 3 are actuated to circuit-openin position, as shown in Figure 2, the notch end of each shutter 3 moves into the adjacent chamber 7 and the imperorate ortion moves partially out of the opposite ciiamber 7 into the space between the jambs 6 for closing the contact-aperture previously provided for the meetin ends 10 of the contact-members 11.

1In c using the said contact-aperture, the wails 9 implnge the then presented ends of the contacts 11, which, yielding to such impingement, arc initially actuated in circuitopening direction, until the toggles are knuckled ,oppositely from their former positions, whereupon the toggles act with increasing force to acceleratively separate the contacts 11 in circuit-opening actuation thereof until bro ht to rest in widely spaced relation by eac impinging the presented yeind of respective stops 21 supported for such purpose on the blocks 17. Such wide spacing of the contacts 11 is accompanied by an inward overlapping movement of the shutters 3 interposing an imperforate insulation wall between the contact-members 11 which electrically isolates each in its respective chambers 4, 5, and su presses or breaks any occurring arc. The w ole circuit-opening action is completed with a snapping action in such a short interval of time as to rupture the current flow and substantially abate the occurring arc before the same can grow to appreciable magnitude.

Surfaoe creepage from the respective contacts 11 to the shutters 3 is prevented by the wide spacing of the contacts from the shutters, which establishes therebetween a substantial thickness of the dielectric fluid contained in the chambers 4, 5, whether the same be air, oil, an inert gas, or other suitable dielectric medium. The shutters 3 co-operating with the jamb walls 6 act to attenuate any occurring ionized air until it is unable to maintain the arc created on separation of the members 1l, such arc being, so to speak,

.snuded ont by the shutters 3.

For closing the circuit, the shutters 3 are shifted or moved outwardly into the respective chambered jambs 6. A pin 22 is laterally presented from each shutter 3 into its adjacent chamber 4, 5. For each respective shutter 3, a spring or tensional member 23 has one end secured to the pin 22 and its other end to the eye-end of a bolt 24 which freely works through an aperture 25 provided in the respective member 11 and has an enlarged head 26 at its other end. When the shutters 3 are closed, each pin 22 moves toward its corresponding contact-member 11, causing the bolt 24 to project somewhat therebeyond. however, when the shutters 3 are opened, each pin 22 moves away from its corresponding member' l1, engaging the bolt 24 with the member ll to thus oppose the tension of the spring 23 to that of the toggle spring 19. j

The several parts are proportioned so that shortly before the respective pin 22 impinges the adjacent short wall of the chamber the force of the spring 23 will overcome that of the spring 19, knuckling the toggle of which the latter is a part in circuit-closing direction. Both pairs of springs 19 and 23 then act to snap the contacts l1 into circuitclosing engagement through the aperture then provided by the now expanded shutters 3, Figure 4.

Straps 27, 28, are secured by a suitable fastening element 29 on opposite sides of the outer end of each shutter 3 with their laterally spaced ends presented into the respective j ambs G. Respective pins 30, supported by and between the pairs of straps 27, 23, work in slots 3l Jformed in the end of' r-espective levers 32, 337 each swingably presented through slots 34 provided in the wall l over each jamb 6. One lever 32 is longer than, and swings oppositely to, the other lever 33. A relatively long bracket 35 is outwardly presented preferably from the top portion of 'the wall l, the one lever 32 extending` therealong and being pivoted at its out-er end on a pin 36 carried by the bracket 35. A relatively short bracket 37 is also outwardly presented from the approximately middle portion of the wall l, the other lever' 33 extending therepast and being pivoted intermediate its ends on a pin 38 carried by the bracket 37.

Spaced parallel members constituting a link 39 are each pivoted at an -end on a transverse pin 4() disposed intermediate the ends of the lever 32. Adjacent their other end. the link-members 39 carry a cross-pin 4l adapted to work in a slot 42 provided in the outer end of the lever 33. Hence, when the link 39 is reciprocated, the lcv-ers 32, 33, are oppositely swung at their respective inner end and simultaneously actuate the shutters 3 towards and away from each other 'for respectively closing or opening the contactaperture adapted to be co-operably provided thereby.

Presented from the opposite side of bracket 35 and out of the plane of swingable actuation of the lever 32, is a pin 43, secured at an end to which an elongated coiled spring or tensional member 44 having its other end stretched past the pin 36 and secured to a pin 45 lixed on the lever 32 intermediate the pins 36 and 49, the pin 45 being presented for such purpose through a slot 46 provided in the bracket 35.

The spring 44 is caused, on actuation of the lever 32, to take a position alternately on opposite sides of the pivot pin 36 thereof. So arranged, the spring 44 and lever 32 cooperatively constitute a toggle, which when knuckled in opposite directions acts to correspondingly actuate its connected shutter 3, and reciprocate the link 39 for opposite actuation of the other shutter 3, such movements being limited by the impingement of the pin 45 with the opposite end-walls of the slot 46, the latter being adapted to limit or stop the lever 32 when the spring 44 is just past the pin 36 in shutter opening position for closing the circuit, so that a very small movement of the toggle will suii'ice to rev-ersely knuckle the same in shutter closing or circuit-opening direction, when the spring 44 acts with increasing force to accclerativelv close the shutters 3 in a manner and at a speed corresponding to the circuit-opening actuation ot the contacts ll.

rllhus the separable contacts ll and closahle shutters are actuated bv an operating means including` tensionally responsive agencies caused to act with increasing force and speed for rupturing the circuit after a relatively small ii'iitial or tripping actua-tion thereof in circuit-opening direction.

Such small initial actuation may be accomplished responsively to current-flow in the protected circuit by an automatic tripping mechanism which includes an electromagnet preferably comprising a pair of windings 47 mounted on a substantially U- shaped core 43 of suitable material, the yoke thereof being engaged by means of suitable fastening elements 49 with a bracket 50 presented rom th-e wall l at its lower portion, at which portion the wall l is preferably reentorced with a post 5l disposed between the walls l, 2. The legs of the core 43 are presented upwardly and terminate in horizontally aligned poles 52.

Electromagnetieally associated with the windings 4T, is a swingable armature 53 having an end extending through a slot 54 in the wall l and pivoted on a pin 55 supported by a bracket 56 presented from the wall 2. Parallel arms 5T are upwardly presented `from each side ot the swingable end oit the armature and have aligned slots 58 in which works a transverse pin 59 carried by the adjacent lower end et the link The pin 59 impinges the upper or outer end wall of the registering slots 56 when the circuit-breaker is moved to circuit-closing position, the armature 53 being then suspended above and over the j )oles with a relatively small air gap therebetween, shown at 60 in Figure 3.

The leads 72, 73, ot 'the circuit to be protected are suitably electrically connected to the terminals 16, i6. and leads 69, 70, serve to connect the wind ings 4T in he circuit. and l prefer to so connect the same that the abnormal current 'dmv in the circuit provides the motivating torce 'for actuation of the armature 53, whereby the latter is caused to actuate the circuit-breaker in a time-interval propcrticnal to the strength et the current-flew in the circuit protected. An inter` mediate tap 7 Vl servesto connect one winding 47 in series with the other and may also be empoyed tor connecting the windings in `parallel with the circuit, if desired. l The response offthe armature 53 ito mnrent f'low in 'the electromagnetic windings 47 is opposed by the force off thespring 44, which is constructed to yield at-a predetermined or abnormal magnitude of current-flow selected with a view ofthe maximum or short-circuit capacity of the-system vbeing protected.

Onocomrence of such short-circuit or overload, .armature 53 responsively acts rto set in motion the entire linkage connected thereto, .the air-gap 60 being selected to allow the armature 53 and initial actuating movement wcient to reversely knuckle the 'toggle of which spring 44 is a part, and at substantially the same time 'to also reversely knuckle the toggiles constituted by the contacts 11 and springs 19, the .pin 59 disengaging the wall of the slots 58 as the link 39 continues in motion after the anmafture 53 seats on the polls.52.

The apparatus also includes a manually manipulative .actuating mechanism for closing 'the circuit-breaker, which comprises means for rendering the tripping means tripfree lor operableindependently ef the actuating means. For such purpose, the lever 32 is provided with .a substantially rhomboidal aperture 61, the upper wall a of which is inclined from the lower wall l thereof, so that the aperture 61 is wider at its front wall c than at its rear wall d. A shiftable latch or lever 62 is pivoted at its lower end on an outwandly presented lever or handle 63 swingable on a pin 64 presented from the bracket 35 and conveniently projecting through a slot 65 provided in the link 39. rhe latch 62 carries at its swingable end a finger or detent 66 laterally presented in the aperture 61 for alternately impinging the several walls thereof. On actuation of the handle 63, the detent 66 shifts correspondingly in the aperture 61. The latch 62 is also swingable on the handlel 63 and urged thereto by a spring or tensional member 67 having its opposite ends suitably engaging the latch 62 and the handle 63, respectively.

On upward swinging of the handle 63 from olf or circuit-opening position to ony or circuit-closing position, corresponding to like positions of the contacts 11, the latch 62 ad- 55 vancingl 1 engages its detent 66 with the aperture-Wallis a. d, at their corner and is frictionally held thereto by the opposition of the spring 44 While so advancing, as shown by dot-dash lines in Figure l, until the toggle of which spring 44 is a part is rcversely knuckle-d in circuit-closing direction. Thereupon, the detent 66 is disengaged from the aperturewalls a, d. the spring 67 swinging the latch 62 until the dctent 66 impinges the opposite cor- 65 ner of the aperture 61 formed by its walls b, c,therdby rendering the lever 32 trip-free of the handle 63, Figure 1.

On circuit-opening actuation of the circuit- `breaker proper, the lever 32 moves independently of the latch 6.2 by reason of the 370 clearance between the top wall a and 'bottom Wall e. As this movement is completed, a stop-pin68 presented from 'the bracket 35 depressingly engages a cam-face e on the latch 62 for clamping or locking the detent 66 into "'15 impingement with `the walls a, d, at their carner, .therebyy restoring the latch 62 to actuating position, ythe final portion of such movement of the lever 32 being imparted to the latch '62 for correspondingly returning the@ handle 63 .to off position.

Thus there an intermediate circuit-opening position of the lever 32 to which it may lie trimaed when the handle 63 is in its on position such position being obtained when"us5 attempting to close the circuit-breaker against a continuingr abnormal condition in the protected circuit. From its on positiom however, the handle 63 may be manu- .a'lly or otherwise swung downwardly, the de- '79 tent 66 engaging the wall b for actuation of the lever 32 in circuit-opening movement until the toggle is broken in that direction, when the spring 44 acts to complete the movement, as above described.

The apparatus provides for a circuit-rup- -turing mechanism adapted especially, though not exclusively, for use with high voltages, and comprises simultaneously movable parts which by their coaction interrupt the circuit in half the time required by either of them alone. Such result accrues by reason of the fact that the circuit-rupturing time interval is a function of therelative speed of the moving parts, and if these parts move simultaneously in opposite directions their relative speed is twice that obtained by their individual actuation.

The design characteristics and assembly of the apparatus are typical for various voltages and current capacity; the distances between parte of opposite polarity and the thickness of the dielectric are proportional to the voltage to be broken. The apparatus is capable of breaking successfully any commercial voltage 1n air or other fluid dielectrics with a minimum disturbance in the line and' at such hi gh speeds that no appreciable thermal effect is noticeable in the operating parts. The circuit-rupturiuer actuation of the circuit-breakor is automatically effected responsively to low of current in the protected circuit and occurs with en initial operating movement applied directly to the shut-ters 3 and contacts 11, which movement so started is completed by the momentum of the moving parts and tensionall;4 responsive means acti-ng with increasing force to move the parts VVat a speed much greater than could be effected by the current-responsive means acting alone. The

current-responsive means initially actuates the arc-rupturing shutters, Which, in turn, impingingly actuate the contacts in circuitrupturing direction. i In such manner, the number of moving parts required is reduced to a minimum, With consequent greater speed of the parts due to a given accelerating force.

Imay add that, in actual practice, a circuit-breaker constructed according to my invention to carry a voltage of 13800 volts broke a large number of dead short circuits at such voltage Without a failure, using air as the fluid dielectric.

It is to be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the circuit-breaker and its associated' instrumentalities may be made and substituted for those herein shown and described Without departing from the nature and principle of my invention.

Having thus described my invention, What I `claim and desire to secure by Letters Patent is:

1. In an electric circuit-breaker, in combination, co-operable contact-members, and means for engaging and disengaging said members for respectively closing and opening the circuit, said means including opposed shiftable insulation-members for co-operably electrically isolating the contact-members one from the other When in circuit-opening position.

2. In an electric circuit-breaker, in combination, co-operable contact-members, and means for engaging and disengaging said members for respectively closing and opening the circuit, said means including a pair of opposed insulation Walls oppositely shiftable for co-operably electrically isolating the contact-members one from the other when in circuitopening position. v

3. In an electric circuit-breaker', in combination, co-operable contact-members, mechanism for engaging said members for closing the circuit, and means for disengaging said members for .opening the circuit, said mechanism including a pair of opposed insulation Walls oppositely shiftable for cooperably electrically isolating the contactmembers one from the other when in circuitopening position.

4. In an electric circuit-breaker, in combination, vco-operable contact-members, mechanism for engaging said members for closing the circuit, and means for disengaging said members for opening the circuit, said mechanism includingl a pair of o-pposed shiftable insulation Walls having connection With the contact-members, and means for shifting said Walls, said Walls When in circuit opening position being interposed between the contact-members for electrically isolating the same one from the other.

5. In an electrical circuit-breaker, in combination, co-operable contact-members, toggle means for normally swingably retaining .said members in circuit-opening position, a pair of opposed shiftable insulation Walls having yielding connection With the contactmembers, and means for shifting said Walls, said Walls on one movement actuating said toggle means for engaging the contact-members for closing the circuit and on reverse movement permitting disengagment of the contact-members for opening the circuit, said Walls being interposed between the contactmembers on circuit-opening movement thereof for electrically isolating the same one from the other.

6. In an electrical circuit-breaker, in combination,cooperable contact-members,spring toggle. means for normally swingably retaining said members yieldingly in circuit-opening position, a pair of opposed shiftable insulation Walls. having yielding connection with the contact-members, and means for shifting said Walls, said Walls on one movement engaging the contact-members against the pull of said toggle means for closing the circuit and on reverse movement permitting disengagement of the contact-members for opening the circuit, said Walls being interposed betWeen the contact-members on circuit-opening movement thereof for electrically isolating the same one from the other.

7. In an electrical circuit-breaker, in combination, co-operable contact-members, spring toggle means for normally swingably retaining said members yieldingly in circuitopening position, a pair of opposed shiftable insulation Walls having yielding connection With the contact-members, and spring-linkage-toggle means for shifting said Walls, said Walls on one movementengaging the contactmembers against the pull of the first toggle means for closing the circuit and on reverse movement permitting disengagement of the contact-members for opening the circuit, said Walls being interposed between the contactmembers on circuit-opening movement thereof for electrically isolating the same one from the other. y

8. In an electrical circuit-breaker, in combination, co-operable contact-members, spring-toggle means for normally swingably retaining said members yieldingly in circuitopening position, a pair of opposed shiftable insulation Walls having yielding connection With the contact-members, springlinkage-toggle means for shifting said Walls, said Walls on one movement engaging the contact-members against the pull of the first toggle means for closing the circuit and on reverse movement permitting disengagement of the contact-members for opening the circuit, said Walls being interposed between the contact-members on circuit-opening movement thereof for electrically isolating the same one from the other, and means responsiveto currenofiow'for initiating movement off seid walls to circuit-opening position.

y 91 In an electr-ical circuit-breaker, in combination, co-operable contact-members, U spring-toggle means ornormally swingably ret'iningsaidmembers yieldingly in circuitopeni position, a pair of opposed shiftable insulation`A wells havin yieldlng connection with the contact-mem ers, spring-linkage- 10 t'oglefmeans for shifting said walls, said .on one movement engaging thecontactmembers against the pull of the irst toggle means for closing the circuit and on reverse movement first impinging the contact-mem- 19 bers for initiatin and then permitting full disengagement o the contact-members for openin the circuit, seid` walls being interposed tween the contact-members on circuit-0 ing movement thereof for electrir 29 cally mating the same one from the other,

and; means responsive to current fiow for initiating movement of scid walls to circuitopening position.

16s: Imi-an electric circuit-breaker, in oom- 25 bination, co-operabie contact-members, mech anism forl engaging said members for closing die-circuit, means for disengaging said members for opening the circuit, seid mechanism inciudin a pair of opposed shifteble 3 insulation wel s having connection with the contawnmnbers, andimeons for shifting said wells, said walls when incircuit opening positianbaingintexposed between the contactL members fon electrically isolating the same i onerom the-other, and means responsive to aiment ilow for automatically initiating monemelft off said walls to circuit-opening L7M. h1' anel'ectricel circuit-breaker, in

i combination, co-operabie contact-members,

spring toggle means for normaily'swingebly retaining seidf members yieldinglyf in circuitopening position, a. pair of op dshittabeinsulation walls having yiel ing-connec- '49 tion with-the contact-members, end means for shifting saidwlalls, said walls on one movement engaging the contact-members against the ull of said toggle means for closing the circuit and on reverse movement 'n permitting vdisengagement of the contact- 'with the contact-members for initiatin 13. In an electric circuit-breaker, in combination, oo-operably engageable Contact members, spring-to le means for disengagingsaid members or o 'ng the circuit, and a pair of opposeddnsnigbn walls oppositely shifteble for electrically isolating the' contact-members one from the other when in circuit-opening position, said walls having connection with the contact-members for yieldingly retaining the same-in circuit-closing engagement against the-pull of said toggie-means.

14. In an electric circuit-breaker, in combi-l' nation, co-operebly engageable contact-members, spring-toggle means for disengeging said members foropening the circuit, and a pair of op ed insulation walls oppositely shiftable ry electrically isolatin -the contact-members one from the other wien in circuit-openin position, seidwalls having connection wit the contact-members for yield ingly retaining the seme in circuit-closi engagement, and means for shitin se' Walls to circuit-opening position, sai weilsi being engageable with the contact-members. on movement to circuit-opening position for* initiafng-eircuinopenin -movement'thereo 15. In am electric cira11tbreafker,in combination, a pair of'opposedsp toggles each comprising a. respective'pivo carrier, contact-members mounted on the carriers and' normally in yieldin circuit-opening disengagement, a pair o relatively shiftable insuletion members having ielding connec-` tion with the contact-mem rs, and means for actuating the shiftafbie members forefLA footing circuit-closing engagement o'f the contact-m, seidwalls being interposed between the contact-members on movement thereof to circuit openingpesition for electrically isolating'the seme one from the other.

16. In an electric circuit-breaker, in com'- binaton, a'pair of opposedsprin toggles each comprising a respective pivote cerner, contact-members mounted on thecarriers and H0 normally in yielding circuit-o nin diseng ment, a pair ofrelatively sliliftagleinll@ ation members, having yielding connection with the contact members, and means for ectuatingthe ,sliitable members for eecti ai circuit-closing engagement of. the contag members against the pull of s aidtogglcs, seid walls beingadapted on movement'thereof'to circuito position for impingement' cirw cuit-opening movement thereof and ing; then interposed between the contact-membersY forl isoletingthe saine electrically one the other.

17'. In an electric circuit-breaker, oo-operable commet-members adapted for separa tion to openthe circuit, means including a. parir ofclosable shutters adapted on closing movement thereof to aetuate seid contactl members in circuit-openingY direction, and m its other means including a member operable.

responsively to current-'How in the circuit for actuating said shutters.

18. In an electric circuit-breaker, (2o-operable contact-members adapted for separa.- tion to open the circuit, means including a pair of closable shutters adapted on closing movement thereof to actuate said coiitaetmembers in circuit-opening direction, means responsive to flow of current in the circuit for initial actuation of said shutters, and means including a tensional member adapted to act with increasing torce for assisting actuation of said shutters.

19. In an automatic circui t-breal:er, a pair of shift-able shutters, a pair of engageable contacts actuable by said shutters, and electro-responsive means for actuating said shutters in one direction.

20. In an automatic circuit-breaker, a pair ct shiftable shutters, a. pair ot engageable contacts actuable by said shutters into and out of Yengagement for res ectively closing and opening the circuit, and electro-responsive means for actuating said shutters in one direction for opening the circuit.

2l. In an automatic circuit-breaker, a pair ot shittable shutters, a pair of engageable contacts actuable by the shutters into and out of engagement for respectively closing and opening the circuit, and mechanism for actuating the shutters int-o circuit-closing position and for rendering the shutters tripiree when the contacts are engaged.

22. In an automatic circuit-breaker, a pair et shiiftable shutters, a pair of' engageable contacts actuable by the shutters into and out of engagement for respectively closing and opening the circuit, and means including a lever and a latch alternately swingable on the lever for actuating said shutters into circuitclosing position and for rendering the shutters trip-free When the contacts are engaged.

23. In an automatic circuit-breaker, a pair of shiitable shutters, a pair of engageable contacts actuable by the shutters into and out of' engagement for respectively closing and opening the circuit, means including a lever and a latch alternately swingable on the lever for actuating said shutters into circuit-closing position and for rendering the shutters trip-free When the contact-members are engaged, and means for restoring said latch to actuating position.

24. In an automatic circuit-breaker, a pair of shiftable shutters, a pair of engageable contacts actuable by said shutters, and means responsive to 'flow of current in the circuit having operative connection with said shutters.

25. In an automatic circuit-breaker, a pair of shittable shutters, a pair of engageable contacts actuable by said shutters, and means including an armature responsive to HOW of current in the circuit having a disengageable operative connection With said shutters for actuating the same in one direction.

In testimony whereof, I have signed my name to this specification.

LYMAN C. REED.

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