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June 21, 1938. K. RQNISBET 2,121,441 CIRCUIT BREAKER Filed Nov. ‘21, 1936 s Sheets-Sheet 1 FIG- 2. a “(\THESD: A ' W (2,iNvENTéR. mam June 21, 1938. K. R NlsBET 2,121,441 C IRCUIT BREAKERv Filed Nov. 21, 1936 3 Sheets-Sheet 2 mwuik, QM ' \NVLNTOR Patented June 21, 1938 UNITED STATES PATENT OFFICE 2,121,441 CIRCUIT BREAKER Kenneth R. Nlsbet, Washington, D. 0. Application November 21, 1936, Serial No. 112,151 11 Claims. (Cl. 200-116) This invention relates to a circuit breaker oi’ moderate rating, suitable for use in the control Fig. 11 is an alternate form of a bimetallic thermal element. of lighting circuits and comparatively small Fig. 12 is an alternate form of contact between power applications and that is automatically op- . the thermal element and the circuit breaker re erable to an open position upon overload, man ually operable to either an opened or closed position, and has for an object a unit that is small and relatively inexpensive. leasing device. tacts. Another object of the invention is to provide a circuit breaker more compact than any hereto fore available and one that can be utilized'in connection with standard single type switch out _ Figs. 13 and 14 are drawings in part showing a multi-pole circuit breaker having separable con ' ‘ By reference to Fig. 1, the numeral l represents a standard sectional conduit type outlet box, 10 commonly used for wall switches and receptacles, let boxes, standard ganged boxes, standard gang in which the circuit breaker is installed. The use of this particular type of outlet box is not boxes with plaster covers or with special boxes 15 if such is to be desired. restrictive inasmuch as the common switch boxes Another object of the invention is to provide a‘ circuit breaker that is interchangeable with many types of tumbler switches already installed, and one that is operated as a tumbler switch in that 20 there is no neutral position of the operating handle, with the attendant disadvantagesthereof. 25 A still further object of the invention is to provide a circuit breaker having inverse time overload trip characteristics with the advan tages of an ordinary tumbler switch thus com bining some'of the merits of both. Other objects and advantages of the invention will be apparent in the description following here inafter. With reference to the accompanying drawings: Fig. 1 is a plan view, partly in section, of the circuit breaker installed within an ordinary sec- ‘ tional type flush mounted outlet box. ' Fig. 2 is an elevation taken along line a—a 01' Fig. 1, showing the circuit breaker in the closed position. Fig. 3 is a part elevation, showing certain ele ments of Fig. 2, with the circuit breaker in the normal opened position. Fig. 4 is an isometric drawing of the carrier assembly drawn to a larger scale, in a position approximately midway between the opened and closed positions, drawn for the purpose oi’ clari-" ?cation. Fig. 5 is a section thru Fig. 4, with the side plates and spring members added.' Figs. 6 and 7 are part sections thru the oper ating and contact carrier heads showing the rela tive positions of the pawl, in thecircuit breaker ~ opened and closed positions respectively. Figs. 8 and 9 are part plan views of the oper ating and carrier heads respectively. ' Fig. 10 is an isometric drawing‘oi the trip and 55 terminal assembly. or ?ttings in general usage can be utilized equally 15 as well, which includes gang and gangable switch boxes or special boxes. The mechanism is con tained within housing 2, having paper or fibre insulation 2a over the top, which is constructed of an insulating material and which has one my removable side 3 for assembly purposes. The housing is secured to the outlet box and covered in a manner similar to that used for ordinary tumbler switches, by means of yoke l and cover plate 5. The mechanism is in general supported 25 in a ‘frame 8 consisting essentially of stop bar 1, pin 8, shafts 9, III, II, and two identically con structed side plates’, only one 12 of which is shown on the drawings, the other side plate l3 being similarly located with respect to the hori- 30 zontal axis and is so designated in Fig. 2. It is to be noted that pin 8 extends into-both sides of housing 2 thru side plates I2 and I3, to form a pivot for frame 6 which has a small angular movement, to be described hereinafter. 35 It should also be noted that stop pin it and trip pin [5 extend into both sides of housing 2 and are rigidly secured in place. The carrier assembly shown in Figs. 4 and 5 consists of two units, one an operating carrier 40 it‘ having a radially curved head ll, a supporting leg IS, the end of which is formed to provide a means for an axis to coincide with that of head H, the said end being provided with a guide 19 mechanically secured thereto, one edge of said . end being cut away or otherwise formed to pro vide catch 20 which is utilized in connection with the tripping mechanism as covered hereinafter. Head I‘! has operating handle 2| mechanically secured thereto and which is of an insulating 50 material, the mechanical attachment likewise furnishing the means of support for spring 22 which is biased to the curvature of head l'l to hold pawl 23 in a normally closed position. Pawl 23 is movable with shaft 24 which in turn is 2 2,121,441 supported by bearings 25 and 28 formed by pro iections from head i1. The other unit of the carrier assembly is contact carrier 21 which has a radially curved head 23 but of a smaller radius than that of head l1, and formed in a manner such that one operates within the other, a sup porting leg 23, which is drilled to support the electrical contacts as described hereinafter, and has its end similarly formed but in the opposite 10 manner to catch 20, to provide catch 38, and has guide 3| mounted thereon. Fig. 5 is a cross-sec tion of Fig. 4, at right angles thereto, and shows the relative positions of plates l2 and I3 to oper ating carrier l6 and contact carrier 21. Spring 15 elements 32 and 33 are mounted about their re spective guides I3 and 3|, their outer ends being secured to plates i2 and I3, their inner ends being in contact under tension to legs l8 and 23 thereby biasing both operating carrier i5 and 20 contact carrier 21 to their normal positions in which the circuit breaker is open. Washer 34 is merely a separating means and an assistant for maintaining alignment of its adjacent parts. Shaft 9 is the common support for carriers l6 25 and 21. Part plan views of ‘the pawl ends of heads l1 and 23 are shown in Figs. 8 and 9 respectively. Head I1 is projected on both sides, which pro— jections are formed to provide bearings 25 and 30 28 while the top inner edge 35 is flat beveled to form a bearing surface for the extreme tip of pawl 23. Head 28 has a longitudinal slot 38 near the end with a rounded or beveled portion 31 between the slot and the end. 35 To open the circuit breaker manually, the fol lowing operation is described, with particular ref erence to Figs. 2, 4 and 5:-—A counterclockwise force is applied to handle 2| which force is trans mitted thru leg l8 to shaft 8 thence to frame 8 thru side plates l2 and I3. The aforesaid force acting thru the described linkage causes frame 5, with all its subioined parts, to rotate counterclock wise thru a small angle about pin 8 against thebias of spring 38. In this angular movement, projec 45 tion 38 of latch-lever 48 is brought into contact with trip pin I5, which being stationary within housing 2, causes the aforesaid latch-lever 40 to rotate about its shaft H) which movement in turn causes tip 4| to be tripped from catches 50 23 and 38 thus releasing both the operating car rier l8 and contact'carrier 21 which being under bias from springs 32 and 33 quickly rotate to their normally open position as shown in Fig. 3. Mercury contact element 42 being secured to leg 55 23 is tilted to an of! position whereby the mercury 43 within the container flows by gravity away from electrodes 44 and 45, thus breaking the electrical circuit. In the first part of this opera tion as operating carrier l6 and contact carrier 21 are tripped, frame 8 is returned to its normal position with side plates 12 and _i3 in contact with stop pin l4, by virtue of the tension in spring 38. - Fig. 10 shows the relative positions of the trip 65 and terminal assembly, consisting essentially of thermal element 48, latch-lever 48 on its shaft l0, spring member 48, trip pin l5, ter minals 45b, 48c and 48d. The action is de scribed as follows: Current from the external 70 source enters the assembly thru wire terminal 48c, ilows thru both legs of thermal element 48 to terminal 48d thence by ?exible connectors, which are not shown, to the mercury contact element, thence back to wire terminal 46!) to 75 complete the circuit. If the current is ex cessive, the free end 45a ‘is de?ected which movement is transmitted thru insulator 41 to rotate latch-lever 40 on or about its shaft in, to trip the circuit breaker as described elsewhere herein. Spring member 48 normally holds latch lever 40 approximately parallel to thermal element 46. Automatic operation of the circuit breaker due to excessive current takes place in the following manner, reference being made to Figs. 2, 3 and 10 4: Current in excess of a predetermined figure thru bimetallic element 45 causes the free end 480. to de?ect in the usual manner. This move ment is transmitted thru insulating pin 41 to projection 48 of latch-lever 40 thereby rotating 15 the same on or about its shaft in against the bias of spring element 49 moving tip 4| from faces 28 and 38 thereby releasing operating carrier 18 and contact carrier 21 to their open positions as noted hereinbefore. Mercury contact element 20 42 being secured to leg 28 of contact carrier 21 breaks the electrical circuit in the manner noted above. The circuit being thus interrupted, cur rent ceases to flow and thermal element 46 grad ually resumes its normal position due to the cooling effect. In the tripped position of the circuit breaker, projection 33 of latch-lever 48 is in contact with the radially curved ends of legs I8 and 28 and is under bias from spring element 49. It is to be noted that ‘with the cir 80 cuit breaker in the tripped position, projection 58 of latch-lever 48 is in a position to strike pro~ Jection 5| of pawl 23 upon reclosure of the cir— cuit breaker unless the free end 46a of thermal elementv 48 is in its normal position, thus pre 35 venting immediate reclosure following a severe overload. Fig. 6 shows the relative positions of pawl 23, heads i1 and 28 when the circuit breaker is open. Upon the approach to the open position, contact carrier 21 is first stopped followed by operating carrier is as their respective heads 28 and I1 strike stop bar 1, as noted in Fig. 3. Pawl 23 moves with head I1 by virtue of its mounting, and projection 52 being biased by 45 spring 22 impinges and rides over rounded sur face 31 falls into slot 36 and thereby engages head 28 which in turn causes carrier Hi to be latched to carrier 21 for the closing operation. To close the circuit breaker, a clockwise force 50 is applied to operating handle 2| to move carrier I8, hence carrier 21, hence mercury contact ele ment 42 in the same direction about shaft 8. With thermal element 48 in its normal position, the above described rotation is continued until 55 portion 53 of pawl 23 strikes stop pin H which action rotates pawl 23 to release head 28, hence carrier 21, permitting the motion of said carrier ' 21 to, be reversed, which reverse motion is ar rested as tip 4| engages face 38. Upon the re~ 60 lease of handle 2i, carrier l8 moves counter clockwise thru a small angle until face 20 is similarly engagedv by tip 4|. element mercury to close ment 45 Mercury contact 42 now being in a horizontal position, 43 surrounds both electrodes 44 and 45 65 the electrical circuit. If thermal ele is in an abnormal position, projection 58 interferes with the clockwise motion of pawl 23, trips the same as projection 5| strikes projection 58 which prematurely releases head 28 hence 70 carrier 21 hence mercury contact element 42 to prevent reclosure of the circuit breaker elec trical contacts. Fig. 7 shows the relative positions of pawl 23, heads l1 and 28 when the circuit breaker is 75 3 2,121,441 closed. It is to be noted that the said heads I‘! and 28 are disengaged as projection 52 rests upon surface 3'! beyond slot 36. It is to be noted that by the use of mercury contact element 42, the circuit breaker is suc cessfully operable only when installed in a ver tical position. To avoid this requirement, I pro pose to utilize separable contacts in lieu of the said mercury contact element, for single or multi 10 pole service, as is indicated in Fig. 13. The use of such separable contacts will permit increased current ratings thus permitting a wider range of the circuit breaker utilization. The design, type and location of spring member 15 38 is that of 'a preferred example but it is not to ceive the motion of either one or all said ther mal elements upon an electrical overload. Sta be so restricted as to exclude the use of another tionary contacts 16, ‘I1 and 18 extend thru hous member of different design, type or location to serve the same purpose, that of maintaining frame 6 in its normal position within housing 2. The U-shaped bimetalic' thermal element 46 noted in Fig. 10 is not necessarily that of a pre ferred example inasmuch as an elongated element of the bar type, or one of the type indicated in Fig. 11 may be utilized, with modi?cations in the wire terminal arrangement on housing 2. It is not intended that the curvature of tip 4| or the angularity and respective lengths of catch faces 20 and 36 be restricted to the design shown on the drawings inasmuch as with modi?cations thereof and with consideration given the lengths of the lever arms and spring members involved, the sensitivity of the tripping arrangement can be reasonably governed, an important factor when dealing with comparatively low current 13 Cl values. Fig. 11 shows an alternate form of a bimetallic thermal element consisting of an elongated por tion of thermostatic metal or of dissimilar metals generally utilized for such purposes, having a ter 40 minal means 54 at each end. A raised portion 55 is provided along the center line of the ele ment, in order to add rigidity to the unit, which may be formed in either of the metals or both. Latch-lever element 40 is constructed prefer ably of an insulating material but is not to be so restricted inasmuch as it may be of metal of a slightly different form. Insulating pin 41 may be eliminated by incor porating its function in another projection 41a to latch-lever 40 as is indicated in Fig. 12, which . serves to eliminate any intermediate element be tween latch-lever 4'0 and thermal element 46. Figs. 13 and 14 show a part assembly of a multi-pole circuit breaker in which the various elements covered hereinbefore are incorporated‘ but with modi?cations that are covered in the following description. The assembly as indi cated is based upon the same fundamental op~ crating principles for manual and automatic op 60 eration, having a movable frame, operating car end of spring member 65 on the other end of which is secured insulator 66 which has mounted thereon contacts 61, 68, 69 arranged to provide wire terminals for the ?xed ends of thermal element terminals 10, ‘H and 12, the latter not being visible in the drawings, by means of ?exible conductors 13, there being one such per thermal element. Insulating barriers 14 are provided be tween adjacent pole terminals and one bar type thermal element 15 is provided per pole. Latch 10 lever 16 has secured thereto, or an integral part thereof, plate 1'! which extends across the free ends of all thermal elements 15 in order to re ing 56 to provide one set of wire terminals 19. Flexible conductors 80 connect the free ends of thermal elements 14 to the other set of wire terminals 8|. , ually or automatically, so far as linkages of me chanical parts are concerned, is as described hereinbefore. Automatic operation from a. closed to an open position is described in part as fol 25 lows: Current in excess'of its rating will, in one or more thermal elements ‘#5 either individually or collectively, cause the same to deflect against plate 11 thus rotating latch-lever .16 on or about shaft 82 which trips legs 58 and 59 to their 30 normally biased positions, thereby quickly rotat ing block 64, spring member 65, insulator 66 with contacts 61, 68, 69 all in a counterclockwise direction thus breaking the electrical contact with stationary contacts ‘I6, ‘l1, 18 to interrupt 35 the electrical circuit. Spring member 65 is so utilized with the forms of contacts noted to permit some latitude due to the movement of the frame in the manual opening operation. With knife contacts in lieu 40 of buttons, block 64, member 65 and insulator 66 may be of unit construction or member 65 may be rigid. It is to be understood that the forms of this invention herewith shown and described are to 45 be taken as preferred examples of the same, and that various changes in the shape, size and ar rangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims. 50 Having thus described the invention, I claim: 1. In a device of the class described in com bination, a means responsive, to a predetermined circuit condition for interrupting a circuit and manually operable to either close or interrupt said circuit, consisting of an insulating housing; a movable supporting member; an operating ele ment; a switch element; a releasable latch ele ment for connecting said operating element to said switch element thru the closing cycle; a. 60 means ?xed to said housing for tripping said latch element; a separate biasing means for each item listed above, that is to say, the sup switch element, and the latch element; a releas ' connection with standard gang outlet boxes or able latch-lever element for locking said operat lating housing 56, side plate 51, operating car rier leg 58, contact carrier leg 59, biasing means guides 60 and 6|, stop bar 62, frame pivot pin 63,‘ and latch-lever 16, other parts and numerals being omitted in order to simplify the drawings. To leg 59 is mechanically secured an insulat 75 ing block 64 which serves as a support for one 20 Operation of the circuit breaker, either man rier and contact carrier elements, trip assembly, , latching elements, pins, stops, shafts and hous ing similar in functions to these previously described but modi?ed for a multi-pole arrange 65 ment with separable contacts and to be utilized in ganged single boxes or with special boxes. The basic elements noted consist of an insu 15 porting member, the operating element, the 65 ing element and said switch element in a closed position; a biasing means for said latch-lever element; the said latch-lever element being piv oted and releasable by a, fixed means1 to rotate 70 the said element about its axis in the manual opening operation and by a thermal element in the automatic operation, the said latch-lever ele ment having two projections, one one either side of its said axis to provide for the'said rotation 75 2,121,441 4 and still another projection arranged to intercept means embodying a biased releasable latch for retaining both said operating means and said switch member in the closed position; a bimetal said releasable latch element to prevent reclosure unless the said thermal element is in approxi mately its normal position; the said switch ele lic thermal element for operating said tripping ment having a means for mounting one or more means. contacts thereon. 2. In a device of the class described in com bination, a means responsive to a predetermined circuit condition for interrupting a circuit and 10 manually operable to either close or interrupt said circuit, consisting of an insulating hous~ ing; a movable supporting frame; an operating element; a switch element; a releasable latch element for connecting ‘the said operating ele ment to the said switch element thru the clos ing cycle; a ?xed means for tripping said latch element, the said means being fixed to said housing; a biasing means for each oi",--the said frame, the said operating element, the said 20 switch element, the said latch element; a re leasable latch-lever element for locking said op erating element and said switch element in a closed position; a biasing means for said latch ~lever element; the said latch-lever element being 25 pivoted and releasable by a means ?xed to said housing to rotate said element about its axis in the manual opening operation and by a ther mal element in the automatic operation, said latch-lever element having two projections, one on either side of said axis to provide means for said rotation and still another projection ar ranged to intercept said latch element unless said thermal element is in its approximately normal position; said switch element having a plurality 35 of contacts mounted thereon. '3. In a ‘device or the class described in com bination, an operating means; a switch element; a biased releasable latch for connecting said switch element to said operating means thru 40 the closing cycle; a tripping means embodying a bimetallic thermal element; a biased releas able latch element for holding said switch ele 5. In a device of the class described in com bination, a biased carrier assembly embodying an operating means and a switch element having attached thereto a contact assembly; a tripping assembly embodying essentially a releasable latch 10 and a bimetallic thermal element, the said thermal element being arranged to transmit a movement therefrom due to excessive current, directly to said releasable latch, said latch being biased and serving a purpose of retaining said 15 carrier assembly in a closed position, one pro jection of said latch moving generally in the same direction as the free end of said thermal element, one projection moving in the opposite direction and another projection moving approx 20 imately at right angles to the direction of move~ ment of said thermal element end. 6. In a device of the class described in com bination, a main supporting element Within an insulating enclosure; an operating means ‘em bodying a biased pivoted member having arr-in 25 sulating operating handle affixed to the head thereof; a switch member having a contact as sembly attached thereto and movable about an axis common with that of the said pivoted mem 30 her; a biased releasable means for latching said operating means to said switch member, sup ported by a pivoted means from said head of the aforesaid pivoted member; the said releasable means having a projection therefrom for the 35 i said latching purpose and another projection arranged to impinge against a ?xed element within the said insulating enclosure in order to rotate said releasable means about its pivot to release said switch member from said operating 40 means essentially at the closed position; a trip ping means embodying a biased releasable latch lever element for retaining both the said operment in a predetermined position and Ior trip ating means and\ said switch member in the ping said switch element under a predetermined closed position by the engagement of one pro 45 45 circuit condition, said latch element being piv jection on said latch-lever element against catch otcd and movable about an axis centrally located faces on the pivoted ends of said pivoted mem and having one projection moving generally in her and said switch member; a bimetallic ther the same direction with the free end of said .mal element for automaticallyv operating said thermal element, another projection moving in tripping means. 50 the opposite direction and still another projec '7. In a device of the class described in com tion moving generally at a right angle to that bination, a main supporting element within an of the free end of said thermal element, one insulating enclosure; an operating means; a said projectidn operating in connection with said switch element having a biased member pivoted , switch element, another said projection operating about an axis coinciding with "that of the said 55 55 in connection with said thermal element and the operating means and having secured thereto a other said projection operating in connection contact assembly; the said switch element oper with said releasable latch; an insulating hous- . ating in planes parallel to and opposite said op ing provided with terminals. erating means and operatively connected to said 4. In a device of the class described in com operating means thru the closing cycle only by 60 60 bination, a main supporting element within an insulating enclosure; an operating means em bodying a biased pivoted member having an insu means of a releasable latch element; a tripping assembly embodying essentially a bimetallic thermal element, ‘a releasable latch-lever element for locking said operating means and said switch element in the closed position, said latch 05 lever element having a projection to provide the means, said releasable means having a projection said locking arrangement, another projection to thereon for said latching purpose, another pro- “ contact said thermal element for automatic tripping and still another projection to trip the jection arranged to impinge against a ?xed ele aforesaid releasable latch element in order to 70 70 ment within said enclosure thereby rotating said release said switch element from said operating releasable means at or near the closed position and thus releasing said switch memberjrom‘said means prior to ‘the normal closed position of the said switch element to prevent reclosure against operating means. said switch member and said operating member thereby moving to their iully overload; said thermal element being of the bar 75 . opened positions ready for reclosure; a tripping type having terminals at each end thereof. iating operating handle affixed thereto; a switch member having a mercury contact element at tached thereto; a biased pivoted releasable means for latching said operating means to said switch 2,121,441 8. In a device of the class described in combi nation, a main supporting element within an in sulating enclosure; an operating means; a switch element consisting of a biased member pivoted about an axis coinciding with that of the said operating means and having secured thereto a contact assembly; the said switch element op erating in planes parallel to and opposite said operating means and operatively connected to said operating means thru the closing cycle by means of a releasable latch element; a tripping assembly embodying essentially a bimetallic ther mal element, a releasable latch element for look ing said operating means and said switch element 1K in the closed position, said releasable latch means having a projection therefrom to provide the said locking arrangement, another projection to con tact said thermal element and still another pro .iection to tripysaid releasable latch element to release said switch element from said operating means prior to the normal closed position of the said switch element. » 9. In a device oi’ the class described in combi nation, an insulating enclosure; a biased pivoted 35 frame element; a biased switch element for -'opening and closing the circuit; a means for op ‘erating said switch element, said means being .operatively connected to said frame element; a tripping assembly embmying a bimetallic titer 3% rnalv element; a biased controlling element op erated by said thermal element, the said control ling element latching said switch element in the closed position and provided with a means to prevent said switch element being‘closed imme— diately following a severe overload, and being of unit construction having a circular movement about an axis and operatively connected to said irame element; said thermal element being of the bar type having a terminal means at each end thereof. 4 - \ iii. In a device of the class described, in com bination, an insulating housing; a frame consist ing of two plates similar in design and purpose, held apart by a plurality of separating means to form a nesting for a carrier assembly, the said frame being pivoted and biased to a predeter mined position, said position being determined by an element fixed to said housing, against which element a projection on each said plate is in normal contact by virtue of the said biasing means; said carrier assembly embodying an op erating member and a switch member having a contact assembly mounted thereon; a tripping 10 means embodying a bimetallic thermal element and a latch-lever clement, said latch-lever ele ment being supported by the said frame and movable with said frame in its angular move ment; a biasing means for said latch-lever ele ment; said latch-lever element'serving the pur IE pose of locking said operating element and said switch element in a closed position and an addi tional purpose of preventing the ?nal closing operation of the said switch element unless the 20 said thermal element is in its near normal posi tion; a means for tripping said latch-lever ele ' ment independent of said frame; the said in sulating housing being provided with wire ter minal means. 25 11. In a device of the class described, a circuit breaker having a slow-make quick-break mech anism, embodying an operating element; a car» rier element for electrical contacts, operatively connected with the said operating element dur so ing the closing cycle and latched thereto in the open position; said operating element and said carrier element each being biased and both sup ported by a common shaft fixed within a pivoted frame; a tripping assembly embodying in part ' a bimetallic thermal element; an insulating housing provided with wire terminals; said mechanism providing a means to quickly open said electrical contacts upon a predetermined circuit condition and to permit a manual reg closure with a slow motion in said carrier do element. KENNETH R. NISBET.