US2372778A - Circuit breaker - Google Patents

Description

April 3, 1945. H. c. GRAVES, JR

CIRCUIT BREAKER Filed April 27, 1940 5 Sheets-Sheet l INVENTORY A'i' TORNEY.

m 5 V A R a. c T. R E: B m

April 3, 1945. H. GRAVES, JR

CIRCUIT BREAKER 5 Sheets-Sheet 2 ITTIIT Filed April 7 1940 V INVEINI'OR HERBERT c .eRAvEs,JR.,

AT To RNEY April 3, 1945.

H. C. GRAVES, JR

CIRCUIT BREAKER 5 Sheets-Sheet 3 Filed April 27, 1940 lNVEN'TOR HERBERT C. GRAVES, JR.

ATTORNEY- April 3, 1945.

H. c. GRAVES, JR

CIRCUIT BREAKER 'Filed April 27, 1940 5 Sheets-Sheet 4 INVENTOR HERBERT C-GRAVES,JR.,

ATTOR NEY.

April 3, 1945. E H. c; GRAVES, JR 2,372,773

I CIRCUIT BREAKER Filed April 27, 1940 5 Sheets-Sheet 5 INVENTEDR HERBERT c .GRAVES, JR.,

ATTORNEY.

Patented Apr. 3, 1945 Herbert G. Graves, In, West Chester, Pa., assignor to I.-T.-E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application April 27, 1940, Serial No. 331,982

7 Claims.

This invention relates to switch gear and circuit breakers, and vmore'particularly to a panel type combination switch and circuit breaker adapted for use in branch circuits of various types and arranged to be mounted upon a panel board together with other similar devices for controlling a plurality of circuits.

In the operation of branch circuits, it is frequently important to connect or disconnect individual circuits from the main line without interfering with the operation of other similar circuits, and toarrange for overload protection for individual circuits so that in the event of any fault in any particular branch, that particular circuit may automatically be disconnected without interfering in any way with the operation of other circuits or with the operation of the main circuit itself.

Thus, in the operation of a plurality of small motors for various purposes in a shop, it is important that any fault occurring in the circuit to a particular motor should not affect the opera.- tion of other motors or the main line to the end that continuous operation should as far as possibie be maintained. 4

Likewise, in the operation of multiple dwellings or apartment houses where a plurality of individual circuits for different apartments are all connected to a single main line, it'isimportant that any particular circuit to any particular apartment be readily connectible to and disconnectible from the mainline and that any fault in any particular circuit should not disturb the operation of any of the other circuits.

Accordingly, the purpose and object of the present invention is to provide a simple combination on-ofi switch and circuit breaker which may be mounted upon a panel board and connected between the main bus and the individual branch circuits in order to provide suitable manual or automatic control for each of the individual circuits.

In order to provide for'panel board mounting of this type and in order further to provide for simplicity in operation and assembly and to facilitate mounting upon the panel board, it is important that the particular combination switch and circuit breaker be compact and nevertheless so arranged as to obviate any internal faults or short circuits.

Therefore, instead of providing for the creation of a simple' air-gap between the movable contact member and the stationary contact member of the on-off" switch circuit breaker combination, one of the important objects of the present invention is to provide for the interposition or an actual physical dielectric barrier between the two contacts when the contacts separate.

-Still another extremely important object of the present invention is to so arrange the stationary and movable contacts that they are separated not by any operation initially performed upon the movable contact itself, but by the sweeping or swinging of the physical barrier of dielectric material toward circuit opening position. In such case, the barrier may swing beneath a bearing on the movable contact arm. raising the arm, and separating the contacts, and then the barrier by continuing the movement reaches its final position between' -the separated-contacts.

The movable contact should therefore be so arranged that it is biased into contactingposltion with the stationary contact in such manner that upon removal of the physical barrier of dielectric material the biasing means wi l immediately re-establish contact pressure between the movable and stationary contacts.

Still another object of the present invention is to provide for individual and separate physical barriers for each of the two operation of crap nary manual switching and automatic switching. That is, one barrier of dielectric material hereinafter referred to as an interposer may be placed between the contacts by manual operation and another such interposer may be interposed between the movable and stationary contacts by automatic circuit breaking means. Both of these barriers may operate in a single plane and it is still another object of the present invention to utilize the manually operated interposer or barrier to remove the automatically operated interposer or barrier from between the contacts when it is desired to reset the switch and circuit breaker after an automatic tripping thereof.

The circuits and apparatus may be designed to carry (a) a maximum current above and below which small variation may occur, (b) a heavy momentary inrush current as in thermal devices such as lamps where operating resistance increases after being switched on, (0) starting currents for motors, (it) short periods such as may occur in motors.

When these momentary increases occur, the length of time they last should be limited by the circuit breaker preferably in accordance with the invention provides for an instantaneous trip mechanism for immediately separating the contacts. Where afault occurs however which is not suflicient to cause operation of the instantaneous trip mechanism, but is nevertheless such that excess heatmay be generated in the circuit, then a thermal means responsive to increased heat in the circuit may be utilized for the purpose of automatically separating the contacts in accordance with th aforementioned PT characteristic.

A further important object of the present in-. vention is to mount the interposer which is automatically brought between the contacts by either of 'the means abovementioned in such a manner that it is always biased toward contact separating position so that in the event of failure of the mechanism, the automatically operated interposerwould be more likely to move to a position separating the contacts than to any other position. I a

A further object of this invention includes the mounting of the manually operated switch lever in such manner that it is yieldingly but positively held in the open circuit or closed circuit position.

Still another object of this invention is to so a arrange the' insulating housing of the circuit breaker that it may be readily molded by means of ordinary core dies without any other expensive molding or forming processes.

Still another and extremely important object or the present invention is the arrangement of the housing of the combination switch and circuit breaker, and thevarious parts thereof in such manner as readily to facilitate assembly. That is, the housing is so formed and each of the parts is so formed that the parts may readily successively beplaced in the housing from one side, the assembly operation requiring merely a series of successive steps without any requirement for complicated tools or complicated supporting and holding means for combining and supporting the members during assembly.

A still further object of the present invention is to so arrange the housing and each of the parts that when the cover plate is secured to the housing at one side thereof, each of the .parts' is securely locked in operative position.

"Many other objects and uses of the present invention will in part be apparent and in part pointed out inthe following description and drawings. i which:

Figure 1 is an external view of the combination switchand circuit breaker.

Figure 2 is an elevational view showing a plurality of the members of Figure 1 mounted uponv a panel board. Figure 3 is a cross-sectional view taken on line 3-3 of Figure 2. I

Figure 9 ma view corresponding to Figure 8;. showing the automatically operated interposer in tripped position.

Figure 10 is a cross-sectional view taken on line l0l 0 of Figure 4.

Figure 11 is a cross-sectional view taken on line li-ll of Figure 10.

Figure 12 is a cross-sectional view taken on line l2-I2 of Figure 4.

Figure 13 is a cross-sectional view taken on line l3-l3 of Figure 8.

Figure 14 is a cross-sectional view taken on line H-N of Figure 11.

Figure 15 is an exploded view of the combination switch and circuit breaker showing the manually operated interposer in circuit breaking position. Figure 16 is an exploded view of the combination switch and circuit breaker showing the automatically operated interposer incircuit breaking position.

trolling a series of branch or subsidiary circuits fed from a main line or bus. The arrangement of the members of Figure 1 upon the panel board as well as the arrangement of th various external portions. of the switch and circuit breaker combination adapting it for use in panel boards will be more readily understood from a description of the interior construction and relationship of the parts of the circuit breaker itself.

The member of Figure 1 is shown in ordinary closed circuit position which, when the cover plate is removed, corresponds to the arrangement shown in -Figure 5; while the arrangement shown in Figure4 shows the position assumed by the parts when the manual operating handle 23 has been moved to open circuit position.

As will readily be seen from Figures 4 and 5,

V the combination switch and circuit breaker com- Figure 4 is a side view of the circuit breaker of Figure 1 with the cover plate removed and'with the contacts and various members arranged in open circuit position.

Figure 5 corresponds to the view of Figure 4 showing the contacts and various members in ordinary closed circuit position. I

Figure 6 is a cross-sectional view taken on line turn conductively connected to the solenoid coil 31. The solenoid coil 31, is connected by means 2,872,778 -of the integral connecting bar 38 to the movable contact-carrying bar 39, the said contact-carrymovable contact surface 4| from'the stationary contact surface 42 when the switch is'closed. The stationary contact surface 42 is carried by the-stationary contact supporting bar 43 (see to the opposite terminal or lead 45 into which the current is led from the bus bar.

It will thus be seen that when the circuit breaker is'so arranged that one terminal 39 thereof is -Figures 13 and 16) which is in turn connected- F by the angular lead-in bar 44 (Figures 4 and 16) connected through the load to one pole of thecircuit and. the opposite terminal 45 (connected.

any separation thereof, will result in an opening of the circuit. Such separation of the contacts may be accomplished either manually, whenever it may be desired, orautomaticallyin response to faults or over current conditions occurring in the circuit which the present circuit breaker is designed to protect.

For the purpose of separating contact surfaces 4| and 42 it may be suilicient merely to move the movable contact a sufficient distance away from a stationary contact so that the air or gases between them furnishes suflicient dielectric interposition to prevent effectively the passage of current therebetween.

Where, owing to the fact that for panel board mounting of these circuit breakers, the various dimensions thereof must be compressed as far as possible and the amount of travel permissible in the movabl contacts is relatively limited, then in order to effectively break the contacts apart so that no current may flow therebetween, the present invention relies not on a sufficient movement of the movable contact to accomplish this purpose, but principally on the interposition of a physical barrier of dielectric material which either effectively serves to lengthen any possible arcing path beyond the limits within which an arc may be maintained for the particular current and pivoting portionBl as well as the foot 52 are integrally molded from insulating material as a single unit.

The interposer 50 securely attached to the foot 52 preferably is formed and pressed from a suitable insulating dielectric material to a thickness facilitating interposition between a movable and stationary contact. The central portion of the manual operating arm 23 comprises, as is more, particularly seen in Figures 4, and 16, a central opening or perforation 10 into which projects a knife edge I l, preferably integrally molded with the entire manual handle portion 23.

Owing to the fact that the handle 23 preferably is made of insulating material which may under appropriat circumstances possibly be brittie, the knife edge H is given a suihciently wide base so that in ordinary operation it will be adequately supported for the purposes hereinafter described. The perforation H! in the manual handle member 23 and the knife edge ll thereof cooperate'to form a relatively frictionless play" less bearing for the handle 23 when the perforation 10 thereof is mounted over the supporting post or spindle l2.

The supporting post or spindle 12 preferably is of insulating material integrally molded as a voltage rating of the circuit breaker or effectively servesto prevent any arcing path whatever.

Accordingly, for manually separating the contact when it is desired at selected intervals to disconnect the particular branch cirouit controll 'i by the switch and circuit breaker combination, I prefer to utilize the manually operated interposer (see particularly Figures 4, 5 and 15). The manually operated interposer 50 is so arranged as seen, in Figures 5 and 4, that it may be readily moved from the position shown in Figure 5 to the position shown in Figure 4, where it is interposed between the contacts as is even more particularly seen in Figure 12.

The manually operated interposer 50 is connected by rivets SI, SI or in any other suitable manner to the foot 52 of the manual operating lever 23. The manual operating lever as is more particularly seen in Figures 4, 5 and 15, comprises a finger grasping portion 63, knurled to insure a firm grip, a foot 52 for supporting th barrier 50, and a central pivoting portion 6|. Preferably the manual grasping portion 50 and the central the central portion SI of the manual operating 5 member cooperates with the remainder of the spindle 12, then the manual operatinghandle' 23 may readily be rotated about the spindle within definite limits or stops. That is, the manual operating handle may be rotated from the position shown in Figure 5 to the position shown in Figure 4; 'in each case the side of the knife edge approaching one of the surfaces of the cut-out'lii of the spindle.

During the actual rotation, the principal bearing surface between the manual o erating handle and the spindle is the knife edge H of the manual operating handle pressing into the angle 14 of the spindle. Thus even though the perforation 10 of the manual operating handle is slightly larger in diameter than the greatest diameter of the spindle, nevertheless the pressure of the knifeedge ll of the handle into the angle 14 of the spindle furnishes an efiicient, play-less bearing.

The bearing herein is described as a playless one simply because it is not a point-to-point contact between a point and an angle but a knife edge-contact over an appreciable length with a corresponding angular member; and such a knife edge contact over such appreciable length prevents any wobble or torque of such nature as to twist the handle out of a plane perpendicular to the axis of the spindle.

The finger grasping portion 60 of the manual operating handle 23 projects through the slot in the upper surface 8| of the housing. The movementof the manual operating handle 23 from the closed circuit position shown in Figure 5 to the open circuit position shown in Figure 4 is effectively limited by the shoulders 82 and 83 which lie at either end of the slot 80 and serve center and serves yieldingly to lock the manual I operating lever in place.

The compression spring 90 (Figures 4, 5 and which accomplishes this function is mounted upon a slidable steel bar 9| which terminates at one end thereof in a yoke or bearing surface 32. Theopposite end of the bar at 93 projects through a perforation 94 in a suitable bearing plate 95, preferably of insulating material. The slidable steel bar is so arranged that the end 93 thereof may slide freely in the perforation 94 of the bearing plate 95. The yoke or bearing surface 92 of the steel bar 9| engages a notch 96 in the peripheral surface of the central portion if of the manual operating arm 23.

'* The spring 90 is maintained under compression between the bearing plate 95 and the flanges of the yoke of bearing end of the steel bar 32. As may readily be seen in Figure 5, when the manual operating arm 23 is rotated into position where the interposer is not between the contacts and hence when the circuit breaker is in closed circuit position, then the effective pressure exerted by the compression spring 90 between the bearing plate 95 and the notch 92 is so directed beyond the center of rotation of the manual operating lever 23 (the knife edge (I and angle 14 engagement) as to exert a torque upon the manual operating lever 23 tending to drive it even further in such direction as to swing the interposer SKI-away from the contacts and to swing the finger grasping portion 80 thereof up against the stop 83.

When the manual operating lever 23 is rotatedv from the position shown in Figure 5 to the open circuit position shown in Figure 4 and the interposer 50 is interposed between the contacts to produce the open circuit position, then as will be noted by a comparison. of Figures 4 and 5, the notch 92 of the central portion SI of the manual operating lever 23 has been rotated to such position that the effective force generated by the compression spring 90 is directed beyond the center of rotation of the manual operating lever in an opposite direction from-that in which it was directed in the closed circuit position of Figure, 5, thus tending to drive the finger grasping portion 60 of the manual operating arm 23 against the stop 82 and tending further to drive.interposer 50 into open circuit position.

Obviously the reason that the compressive force" of the spring 90 is either in the open or in the closed position exerted in such direction as tomaintain the particular position ofthe switch (whether open or closed) is that the axis of the spring is in each case shifted beyond the center of rotation so that the effective direction of the force exerted by the spring changes from a counterclockwise direction with respect to Figure 5 to a clockwise rotation with respect to Figure 4 about the center of rotation.

.A will be noted from a comparison of Figures 4 and 5,v the spring ill is in aposition under greater compression and much less beyond center when the switch is in the open circuit position of Figure 4 than when the switch is in the closed circuit position of Figure 5.

Accordingly, a positive closing action is provided for the closing of the switch, that is, it

requires only a slight movement of the finger grasping portion 50 of the manual operating lever 23 (when the circuit breaker is in the position shown in Figure 4) to move the ,manual operating lever 23 .so that the force exerted by the spring 90 passes through center and is exerted in an opposite sense to snap the manual operating arm 23 into closed circuit position.

Thus, when the switch is in open circuit position, it requires merely flicking of the finger grasping portion 60 of the manual operating lever 23 to cause the interposer 50 to be snapped out of its position between the movable .and stationary contact. Also for this reason, the possibility that the contacts might-remain in bare proximity to each other without actual complete removal of the interposer 50 is greatly minimized since in the circuit opening position it is necessary for the circuit opening movement to be substantially completed manually or else the manual operating lever 23 and the finger grasping portion 60 thereof will immediately snap back to circuit closing position.

The position of the finger grasping portion 60 of the manual operating lever 23 generally will indicate the on" or off condition of the switch unless the switch or circuit breaker has been automatically tripped open in which case other indicating means hereinafter described may be utilized.

In order that, upon the removal of the barrier 50, from the position shown in Figure 4;;where it is between the movable and stationary contact to the position shown inFigure 5 where it is no longer between thesecontacts, the movable contact should come into closed current conducting contact with the stationary contact, I provide a leaf spring I00 (Figures 4, 5 and 16) which tends to drive the movable contact surface 4| (see-also Figure 13) down upon the stationary contact surface 42. The. leaf spring fill] preferably is mounted upon a surface Hit" of the housing and secured thereto by a washer I02 and one of the rivets 220 which serves to secure the cover plate 2| to the housing. In order to insure that the leaf spring will be accurately positioned to exert proper contact pressure upon the movable contact, I provide a lug I03 extending from the leaf Spring and registerable' with a recess I of the housing which registry will serve adequately to prevent undue rotation of the leaf spring around the screw 22a.

The leaf spring I00 preferably is formed of any suitable elastic-metal preferably of spring steel and is so arranged and bent as seen particularly in the perspective exploded view of Figure 16 as, to exert pressure upon the contact-carrying arm 39 in such direction as to bias the contact block '40 and the movable contact surface 4| thereof into engagement with the stationary contact surface 42.

In orderfurther to .ensure that the movable contact-carrying arm 39 cannot escape the pres- 79 sure, I prefer to shear the end H0 of the leaf tact surface 42.

as'raws bar from the leaf spring and vice versa.

Obviously a great deal of friction would be generated by the movement of the barrier 50 between the surfaces H and 42 of the contacts unless some friction reducing means were provided. Such friction reducing means, however, must be of such a nature as not in any way to interfere with the effective pressure between the two contacts when the circuit is to be closed, while it must be readily usable to reduce the friction caused by I2I which is in turn mounted in the perforation I22 of the movable contact block 40.

The stationary contact surface 42 projects somewhat as will be seen in Figure- 13, above the main portion of the stationary contact-carrying bar 43. In order to protect the Bakelite'houslng 20 from the effects of any" momentary arcing that may occur during the instant o breaking of the contacts, an insulating plate of any suitable material I30 (see particularly Figures 8 and 13) is placed upon the inner side of the housing and over the stationarycontact supporting members.

The insulating plate I30 has a perforation I2I therein which registers with the stationary eon- The insulating plate also has.

first comes into contact with the wheel I in order to facilitate the raising of the wheel. However, ordinarily the interposer 50, although it is of suflicient thickness to provide for a sufficient dielectric barrier between the contacts when it is in open circuit position and although it is of sufficient strength to permit it to separate the contaots by the means herein described it is nevera perforation I32 therein which provides a recess into which the wheel I20 may descend "so that adequate pressure may be maintained between the contact surfaces 4i and 42. In order further to protect the housing 20 at I35 from any arcing that might occur during the instant of opening of the circuit, an additional small plate I30 of insulating material is placed beneath the perforation I32 effectively to protect the housing from any stray arcs that might momentarily exist.

when the contacts are in closed circuit position, it will thus be noted by reference to Figure theless sufficiently thin so as to not make any such bevelling essential for the purpose of. lifting the movable contact wheel.

By this means, therefore, the contacts may be manually opened or closed from the outside of the housing by merely applying finger pressure in the proper direction to the finger portion 00 of the manual operating lever 25.

In the event of sudden overloads of great in tensity or in the event of a sudden large drop in resistance, it becomes important immediately and automatically to open the circuit, that is, to separate the movable and stationary contacts. Likewise, also, in the event of an overload of less intensity or a drop in resistance below normal and sufficient to permit the passage of current to such an'extent as to cause over-heating, means are provided in thev present device for also separating the movable and stationary contacts andthereby opening the circuit at that point.

Both of such means, that is, the means responsive to sudden increased'overloads and the means responsive to milder overloads which eventually may be deleterious, are so arranged as to actuate the automatically interposable barrier or interposer I50 (see particularly Figures 8. and 9 as well as Figures 15, 4 and 5) The autowhich ispreferably made of substantially the 13, that the contact surfaces 4| and 42 may come into close positive abutment in relation to each other owing to the fact that the recess I32 in the to prevent friction between the interposer and the contact surface.

' When the interposer slides between the contacts it, however, as will clearly be seen byv a compar son of Figures 4 and 5 with Figure 12,

first comes into contact with the freely rotatable wheel I20. Since the wheel is freely rotatable the barrier may readily slide thereunder and owing to the fact that the barrier is arranged so as to The depth of the recess is such as to provide allowance I for this additional movement during the life of the breaker. The prime purpose of the'wheel is be unyieldingly mounted in its own plane, then the continued sliding of. the interposer 50 owing to manual or other pressure, will cause a raising of the wheel I20'and a consequent raising of the movable contact block 40 and of the movable contact surface 4 I, thus permitting the interposer 50 to slide between the contacts.

In order to. facilitate this, the interposer 50 may be bevelled at the leading edge thereof which same dielectric material as the in'terposer 50, a central portion III and a latch engaging arm I52.

The central or mounting portion I5I of ,the automatically interposable interposer I50 is as is most clearly seen in Figures 8, 8 and 15, perforated at I53 to permit the mounting of the interposer I50 upon the spindle I2.

The spindle 12 has an increased diameter at I54 which is the base portion thereof, most closely adjacent to the wall of the housing. The cutoutportion I3 of the spindle -12 nevertheless extends into this larger portion of the spindle and the angle I4 formed between the surfaces of the cut-out portion also. etxends into the enlarged portion of the spindle. The enlargement of the spindle I2 at I54 permits not only for a more secure connection between the spindle and, the

wall on which it is mounted but also serves to register and align the various members upon the spindle. That is, the perforation I50 of the automatically interpo'sable member 150 is of a size permitting accurate registry of the; perforation I53 with the large portion of the spindle I54, while the perforation I0 of the manual operating lever 23 is of a size registering with the narrower portion of the spindle I2.

Thus after the automatically interposable mem vber I50 has been placed upon the wider portion of thesplndle I54, the manual operating lever may be placed thereon and by reason of the fact that the side thereof abuts against the surface portion I00 of the wider portion I54 of the spin- "dle, the manual operating lever cannot in any way interfere with the operation of the automatically interposable interposer I50. This is more particularly so since the mounting portion I5I of the automatically interposable member I58 is slightly narrower than the length of the wider portion I54 of the spindle I2 so that the mounting I5I may 'be free of contact with the, central mounting portion 8| oi the manual operating lever 28.

The interposable barrier I50 is so arranged that it may be readily rotated about the portion I54 of the spindle. For this purpose, an angular projection IGI is integrally extended from the body of the mounting section I5I of the interposable member I50 into the perforation I53. The angu lar projection IBI registers with the angle '14 in the spindle and provides .a suitable bearing for the rotation of the automatically interposable barrier I50.

Rotation of the automatically interposable member I50 about the spindle is also limited by the spacing of the walls of the spindle which surrounds the angular portion 14 thereof. That is, as seen in Figures 8 and 9, a positive stop is provided in each direction of movement of the interposer I50 by the abutment of the sides of the angular portion IS! against the walls of the spindle which join to form the angle I4 thereof.

A compression spring I70 (Figure 8) is mounted on a steel slide bar I1 I. The steel slide bar has a yoke or bearing surface I12 which at one end thereof bears against a notch I13, of the automatically interposable interposer I50. At the opposite end of the slide bar the bar is at t inserted in a perforation I'I5 of an insulating hear ing plate I15. The end I" may slide freely in the perforation I15.

Compression spring I70 is under compression between the bearing plate I16 and the flanges ofthe end bearing I12 01 the steel slide bar I'Ii. As may be noted especially in connection with Figure 8, even when the automatically interposable barrier I50 is not between the contacts'the axis 01' the compression spring "0 is so arranged that the force exerted thereon is to the left of the center of rotation at I8I and hence is so directed as to cause the interposer I50 to rotate in a. counterclockwise direction with respect to Figure 8.

The interposer I50 is restrained from counterclockwise movement in response to the action of the metal bearing I80 and the latch I 8| there,

is no further restraint upon the rotation of the barrier I50 and since the action of the compression spring "0 is such as to immediately initiate counterclockwise movement thereof with respect to Figure 8, then immediately upon such disengagement, the compression spring IIIl will force the interposer I50 into the position shown in Figure 9 where it extends between the movable and stationary contacts.

The open circuit position of the barrier I58 is definitely fixed by the abutment thereof against the-edge oi. the handle shutter 50 which thus halts continued rotation of the interposer I50 in response to the action of the spring I'ID.

cult breaker. the interposer I50 will be positioned as shown in Figure 9 directly between the movable and stationary contacts.

The abutment of the edges of the shutters in the tripped position forms a complete continuous seal between the contacts cutting oil any possible effective are path. Thus it may be seen by a comparison of Figures 8 and 9 with Figures 4 and 5, that when the manually operated interposer 50 is in the closed circuit position of Figure 5, a free path is provided for the descent of the automatically operated interposer I50 50 that it may readily move from the position shown in Figure 8'to the position shown in Figure 9 immediately upon release of the latch II of the trigger I82 from its engagement with the metallic bearing surface I80 of the latch engaging portion I52 oi the interposer I50.

Therefore when by the operation of the manual operating lever 23, the barrier is moved to closed circuit position, that is, to a position where it no'longer extends between the movable contact and the stationary contact, no impediment of any kind exists to the automatic interposition of the interposer I50 between these contacts in response to a release of the latch engaging portion thereof I50 by the trigger i132.

Normally when no fault condition exists upon a line, the trigger I82 is so arranged that the latch portion i8I thereof engages the bearing I80 of the interposer I50. For the purpose of retaining the interposer in the desired non interposing position, the trigger I82 is spring biased by means of spring 200 (Figures 10 and 11) into latching position.

The trigger I82 has a central mounting portion 20i which is perforated at 202. An integral projection of the material of the trigger 203 extends into the perforation 202 and terminates in a pointed angular portion 204 which provides a bearing for the trigger upon its shaft, permittin rotation thereof upon the shaft within predetermined limits. The mounting of the trigger. as is seen in Figures 10, 11 and 14 comprises a spindle 2I0 preferably integrally formed from and se- -"cured to the wall of the housing and having a By proper arrangement and spacing of the shutters (that is the closed circuit non-interposing position of theshutter 50 and the open circuit interposingposition of shutter I50) it is possible to ensure that m the tripped position of the cirnotch 2| I therein.

The angular point 200 of the trigger projects into the notch 2i I which thus provides an angular bearing surface. The trigger I82 may thus rotate within predetermined limits on the spindle 2I0. A sleeve H2 is mounted on the spindle 2I0 and between the side of the trigger and the side of the cover plate, thus accurately positioning the trigger upon the spindle. A hole in the spindle 2"! at 2I3 {Figure 10) permits one end of the spring 200 to enter therethrough and engage a wall of the groove or notch 2; the spring is wound about the sleeve, the other end at 2IB engaging the trigger I82.

The spring is so arranged that it exerts a rotative force upon the trigger about the spindle 2I0 in a counterclockwise direction with respect t Figure 9 and hence tends to bias the trigger I82 so that the latch portion I8I thereof is positively .in engagement with the metallic bearing I of the latch engaging portion I52 of the interposer elements which respond mechanically to variations in the amount of current.

Trigger release arm 220 is so arranged as to cooperate with the member 245 of the solenoid assembly 230 in the manner shown in Figures 4, 5, 8 and 9. As has been above noted, the solenoid is in the current path through the movable and stationary contacts. Thus, with respect to Figure 4, the current enters at the connecting lug or terminal 45, passes through the contact blocks and the members 39 and 38 into the coils 31 of the solenoid and thence through the wire'braid 85, the thermal element 34 and the lug 33 and bar 32 into the opposite terminal 30.

The solenoid coil 31 is composed of several turns of conducting material which, in the preferred embodiment of'the present invention, is

'square copper of substantial cross-section. The

large cross-sectional areaiminimizes the resistance which is injected into the circuit and also increases the actual physical strength of the coil, thus making it possible to use an integral extension 3M9 of the solenoid coil itself as the lead in and physical support for the movable contact block.

It will be noted -that the contact engaging spring I forces the contact member 40 toward the molded wall of the housing. The point of engagement of this spring with the bar 38 is between the contact and the coil. The spring thus produces reactions at each end of the bar 38-49: one, producing contact engaging pressure when the interposers are retracted; the other maintaining the solenoid assembly in its sockets.

To obviate .the necessity for insulation on the solenoid, the coil preferably is wound. with a reasonably large air space between the turns. The solenoid coil 31 as is seen in Figures 4, 5, 8,

and}? is mounted on an insulating sleeve 23I which prevents any'current leakage between the successive turns of the coil and at the same time serves to insulate the coil from other members of the mechanism.

The insulating sleeve 23! may be secured with- I in the housing in any suitable manner. Thus one end thereof may at 232 be supported in a depression of the bottom wall of the housing and the opposite end thereof may be supported in a U-shaped member 233 preferably integrally molded from a wall of the housing.

For purposes of securing the support of the sleeve 23I at 232 in the housing, a steel core 234 having a flange 235 engaging the sleeve may be secured at the bottom of the sleeve to provide a suitable bearing for the main armature spring and further to rigidify and strengthen the sleeve against any stresses that may be placed thereon.

The movable solenoid armature 240 is slidably.

mounted in the top of the sleeve 23I'and preferably may be maintained in the normal raised position shown in Figure 8 by the compression spring 2 which is placed between the base of the -movable armature and the top of the stationary core. Since the slidable armature 240 is preferably made of steel or any other suitable magnetizable material, it may be drawn down so that it extends substantially within the coils 31. of the solenoid when a suiilcient current is passed through such coils.

Spring 2 of the solenoid should be so calibrated and arranged that it will permit the drawing of the armature 240 within e coils of the solenoid in response only to an ove oad sumciently excessive to possibly cause damage. That is, the spring I should not permit descent of the solenoid armature 240 when ordinary currents customarily to be expected in the circuit are passing through the coil 31. Nor should it even permit descent of the armature when only slightly excessive currents are passing through the coil. But the movement of the armature 240 into the coil should be in response only to excessive loads.

The circular cross-section of the armature 240 and the free, fit thereof within the sleeve 23I permits it to slide readily. A rectangular trigger arm engaging member 245 is secured either by welding or by any other suitable means to the top of the armature. Figure 15, the trigger arm engaging member 245 is squared-off and preferably the interior wall 245 (Figure 9) is close to the plate 245 of the armature (see also Figure 6).

As is therefore seen particularly in Figure 6, while the squaring-off of the plate 245 does not interfere with the rise or fall of the armature, it prevents undue rotation of the armature to ensure that the trigger arm engaging portion thereof will always extend in such a direction as to engage the trigger and to ensure that it will not rotate out of engagement with the trigger.

The slots 241 (Figure 16) cut into the armature 2M and magnet 234 and the slot 248 out into the trigger arm engaging plate 245 serve to prevent eddy currents which might otherwise tend to reduce the total magnetic flux in the circuit 'or occasion any loss of energy owing to heating.

When an overload occurs for any reason causing an excessive current to pass through the coil 31 of the solenoid, then the armature 240 is attracted into the coil of the solenoid, the plat 245 engages the trigger arm 220, presses the arm downwardly with respect to Figure 9, causes a rotation of the trigger about the spindle 2I0 in a .direction opposite to that in which the trigger was originally biased by the trigger spring 200, causes a movement of the latch portion I8l there of out of engagement with the bearing I80 of the latch engaging arm I52 of the interposer I50 0 and" thus removes any restraint upon the rotaf tion of the interposer I50, thereby permitting the compression spring I to drive the interposer from the position shown in Figure 9, where the interposer I as will now be clearly understood,

W extends between the movable and stationary contacts.

nbviously, any such tripping of the interposer I50 into circuit opening position shown in Figure 9 will not occur owing to the energization of the 6-: solenoid 230 unless the movable and stationary contacts are pressed together, that is, unles the entire mechanism has first been placed in the position shown in Figure 5 where the manually operated interposer 50 is no longer between them.

As will be noted in Figure 5, when the manual- 1y operated interposer I0 is moved from the open circuit position of Figure 4 to the closed circuit.

position of Figure 5then' not only does it permit the circuit to be closed between the movable and stationary contacts but also it is moved to a position where it will not interfere with the descent of the automatically operated interposer upon release of its latch engaging arm I52. So that when the automatically operated interposer I50 moves from the position shown in Figures 5 and 8 into the position shown in Figure 9, in response to over current conditions, 'it-is-clearly free to do so without interfering with the interposer 50.

Obviously when the interposer I50 moves from the position shown in Figures 5 and 8 to the Preferably as is seen in position shown in Figure 9, it engages and raises the wheel I20 and separates the stationary and movable contacts in exactly the same manner as has been shown heretofore in the manually op-'- erated interposer 50. The manually operated interposer 50 is off-set out of the principal plane of the main portion of the manual operating lever 23 so that it will be coplanar with the-automatically operated interposer I50.

This condition simplifies the resetting process when the automatically operated interposer I50 to its original position preparatory to latching engagement with the arm I52 of the interposer I50. Since the interposer 50 and the interposer I50 are coplanar with respect to each other,it will i be then clear that the movement of the manual operating lever 23 from the closed circuit position shown in Figure to the open circuit position shown in' Figure 4 will result in a corresponding movement of the interposer 50 as shown and will also therefore result in the pushing up of the interposer I50 by the interposer 50,

despite the force of the spring. In such later case, spring 24I will not be necessary. v

Ihave here shown, however, the preferred embodiment wherein compression spring I which may readily be calibrated is utilized to resist the force exerted upon the armature by the passage ofcurrent through the solenoid. By this means, the automatically operated interposer I59 may be tripped in response to a' specific excessive overload of substantial extent; It may be necessary or desirable to effect a similar tripping operation of the interposer I50when an overload which is not greatly excessive but'is nevertheless continuous occurs.

In order to accomplish this purpose, I provide a thermal bi-metallic element 34 (Figures 4. 5, 8 and 9) which is responsive to heating eifects. which may occur in this circuit. The thermal -bi-metallic element 34 is so arranged that the lower end thereof will be rotated clockwise with respect to Figure 8 under the influence of heat. The current path from the connecting lug through the contacts and to the connectin lug When the manually operated interposerf has been moved into position shown in Figure 4. it

will have raised the automatically operated interposer I50 so that the latch engaging arm I52 will be in latchin engagement with the latch I8I of the trigger I 82. And the circuit breaker will havebeen restored to its original non-tripped position but the circuit will then remain open since in the very operation of resetting the 'interposer I50, the interposler 50 has been moved into position between the contacts.

Subsequent to this operation which thus results in the position of the members shown in Figure 4, in order to restore the circuit, the manually operableinterposer 50 must be moved back to the position shown in Figure 5.- If, during such movement, and at the moment the mov able contact touches the stationary contact, over current conditions still exist on the l ne. thenthe solenoid coil 31 will be immediately energized to trip the automatically interposable barrier I50 to tripped position. I

It is thus absolutely impossible to 110171 the circuitf closed when over current conditions exist on the line and to this extent at least the present invention isa. trip-free circuit breaker. In other words, the tripping action which results in the placement of the interposer I50between the movable and stationary contacts occurs independently of the manual operated lever 23.

The spring 200 wh ch biases the trigger I02 in the proper position should preferably be only oi sufllcient strength for this purpose. Otherwise it will be necessary not merely to calibrate the spring 2 of the solenoid in accordance with the particular overload current conditions which are to be expected but also to calibrate the spring 200, in accordancetherewith.

It will also be possible, should it be desirable. merely to depend on the spring 200 of the trigger and to arrange this spring so that it will permit a release of the latch only when a suillcient force is exerted upon the armature to rotate the trigger 30 is through the thermal element 34. Thus the currentis led from connecting lug 45 through the bar 44 to the contact surfaces 42 and 4|, the contact supporting arm 39 and 38, the. solenoid coil 31, the wire braid 35 to the thermal element; from the thermal element, the current flows into the thermal element supporting arm 33, thence through the bar 32 to the opposite connecting ter minal 30. V

Any overload conditions on the line which may result in the passage of suflicient current to generate heat in the circuit but which may not be of suilicient intensity to energize the solenoid 230 may nevertheless be sufiicient' to. cause 'a bending of th thermal element 34. The thermal element 34 preferably is so calibrated that it will bend into engagement with the arm 22: of the f trigger under predetermined excessive load "conditions which are not greatly in excess of the desired current condition but which nevertheless resuit in the generation of excessive heat.

Upon the bending of the thermal element 34 in response to such heating conditions in the circuit,

the end thereof will be swung over in the manner shown in the dotted. lines of Figure 5 into mechanical contact with. the trigger arm 22I and will cause a. rotation of the trigger I82 about the spindle 2| 0, such rotation releasing the latch portion I!" thereof from the metallic bearing I80 of the latch engaging arm I52 of the automatically interposable interposer I50.

This permits a tripping operation to occur and I permits the compression spring I10 to force the automatically operated interposer I50 into the position shown in Figure 9. i

The automatically operated interposer may then be reset in the manner above described by the operation of the manual operating lever 23, but the trigger I82jwill not be rotated to latching position by its spring 200 until the heating conditions which resulted in a, curling of the thermal element 34 have been removed.

Thus, should .the'interposer I50 be reset in the manner above described immediately after tripping in response .to heating conditions, it will immediately trip once more'owing to the fact that the thermal element will not have had an opportunity tocool off sumcientlyto permit it to disengage the trigger arm 22 I. For this reason,

. therefore, the interposer I 50 cannot be reset until whatever heat has already been generated in the circuit has'had an-opportunity to radiate away.-

' broken.

cessive overload occur, the solenoid operating mechanism 230 will cause another tripping; and should there be' in the case of such resetting a slight overload resulting in the generation'of heat once more, then after heat has been generated for a sufficient amount of time to permit the curling over of the thermal element 34, the interposer I50 will again be tripped and the circuit In every case it must be understood'that the operation of the interposer I50 is completely free of the manual operating-arm 23 and that it is absolutely impossible to maintain thecircuit in closed circuit position when fault conditions exist upon the line.

The circuit breaker may be adjusted for different types of excessive overloads by proper calibration, and interchanging of the spring 2, and it may be adjusted for different responses to slight or heating overloads=by either a change in the bi-metallie elementor a shifting of the bi-metallic element 34 with respect to the trigger arm 2 2I so as to require a diiference in the amount of bending of the thermal element before it is in mechanical contact with-the trigger arm 22I.

In order to provide for such shifting of position I provide that a screw 210 be threaded through the arm 33 which supports the thermal element 344and that the end of this screw bear- 300 and extending as is shown in Figure 9 im mediately below the latch engaging arm I52 of the interposer I50.

A spring303 (Figure 9) is at one end thereof engaged in an opening 301 of the automatically operated interposer I50 and at the other end at 308 is caught beneath the finger 305. The central coil portion thereof is wound about the shaft I2 ing against the ledge 2H in the interior of v the housing. The arm 33 is made of resilientconductive material and is sufficiently elastic so that upon rotation of the screw 210 the arm 33will be moved closerto or further away from the ledge 2II thus changing the position of the mounting of the thermal element 34 and shifting it closer to or further away from the trigger arm The mounting portion 8| of the manual operating lever 23 is so arranged-that whatever the position of the manual operating lever, whether on or oil, the slot 80 is completely covered over so that virtually no dust may enter from the outside into the mechanism.

This results, however, in making it either difficult or impossible to examine the interior of the mechanism while the circuit breaker is mounted upon the panel board to determine whether the circuit breaker has been tripped. As a matter of fact, even though the finger grasping portion 80 of the manually operated lever 23 is in the closed circuit position shown in Figure 5,- the circuit breaker may be tripped open by the dropping of the interposer I to the position shown in Figure 9 without changing the position of the finger grasping portion 80. Thus unless some outward visual indication is provided as to the position of the interposer I50, it will be difficult if not impossible to determine whether a circuit breaker hasbeen tripped.

Accordingly, I have provided a visual indicator which will readily show the position of the .automatically operated interposer I50. The visual indicator is preferably a fiat metallic member 300 (Figures 5 and 16) carrying a flag "I and having a perforation 302 registerable with the mounting shaft 12 and an angular projection 303 registerable with the angle 14 of the mounting shaft. The indicator 300 is mounted upon the shaft 12 above the interposer I50 and the mounting portion SI of the manually operated lever 23. The indicator disk 300 also has a finger 305 preferably at right angles to the main portion of the disk and is placed between the automatic interposer I50 and the manual operating arm mounting CI. The spring 306 and especially the, end 303 thereof is therefore biased to raise the'iinger 305 and thus is biased in such a direction as to cause a. rotation of the disk 300 so as to raise the flag 30I. Normally, however, when the automatically operated interposer I50 is in the latched position shown in Figure 8, the latch engaging'arm I52 thereof presses down the finger 305 against the bias of the end 303 of the spring and hence also presses down the flag 30l so that it is not visible. .When theautomatically operated interposer I50 is tripped into the position shown in Figure 9 and the latch engaging portion I52 thereof is raised, then the end 308 of the spring pushes up the finger 305 of the indicator and pushes the flag 30I upinto the slot 30 where it may be visible from the outside alongside the mounting portion SI of the manual operating lever 23.

Accordingly, even though the finger grasping portion 60 of themanual operating lever 23 is in the apparent closed circuit position, the appearance of the flag 30I in the slot alongside the mounting portion 6| of the manual operating lever will immediately give an indication that the circuit breaker has been tripped to open circuit positions 1 In order to provide a recess in the mounting portion 5| to permit the flag 301 to appear in the slot 80, the mounting portion SI is cut out at the flag 30! therein (3l0, Figure 5).

In order to prevent any possibility during the,

opening of the contacts of any arcing over between the movable contact block 40 and the bar 44, I prefer to provide insulatin barriers 320 and 32I (Figure 5) which may be mounted in notch 322 of the ledge or boss 323 in the bottom wall of the housing and in notches 324 and 325 of an end wall of the housing.

In order further to protect the members against arcing, I provide an upper shield 340 (see Figures 5 and 16) having a T-shaped opening 3 therein to permit the engagement of the contacts and the passage. of the wheel therethrough. This protective shield may be formed or stamped to shape, the shape being, of course, determined by the contour of the housing and obviously this shield 340 is spaced from the bottom shield I30 by a distance sufllcient to permit the free passage of the insulating interposers between them.

From the foregoing description it will be seen that each of the members of the circuit breaker is supported within the housing in such a manner that they may readily be assembled in connection therewith. The housing itself is so formed and constructed as to provide supporting elements of various types, most of which having hereinbefore been described. Thus, for instance, the bar 32 which is an extension of the connect ing lug 30 is securely mounted within the housing assembly by the screw 360 (Figures 4 and 5) which passes through a lug 36I of the bar 32 and into an integrally molded rectangular support 363 of the housing. The bar 32 is also securely positioned within the housing by being M0 to a depth sumcient to permit the entry of mounted between the rectangular abutment 308 and the angular portion 884 of the housing.

Each of the interposers and the manual operating lever rotates about a single spindle which is integrally molded from or secured to one wall of the housing.

The member 44 which carries the lug 45 is also securely mounted within the housing, as is seenin Figure 9, by being mounted in a recess or channel 388 thereof. The various portions of the housing cooperate with other elements to provide stops for certain of the movements and to provide moun'tings and securement in the manner hereinbefore described. When the cover plate 2| is secured in place by the rivets 22, then each of the members is securely fixed in its operative position, particularly as is seen by the cross-sec tional view of Figure 6. e Thus, the final securement of all of the members isobtained after most of the members have merely been slipped into place by the attachment of the cover member II andthe passing of the rivets '22 through the elements and the housing.

Obviously, suitable on-oi! indication may be printed or written on the outside of the housing in cooperation with the manual operating lever 23 and particularl the lingo:- graspi portion I50. I! so desired the mounted portion 6| of the manual operatinglever may be lettered with the legend "off" at 310 (Figure 4) and with the legend on at "I (Figure 5). Furthermore the indentation 312 of the mounted portion 0! of the manual operating lever 23 may be provided and may be suitably colored to indicate the -on" pomtion, since it will be visible only when the finger grasping portion of the manual operating lever 23 has been moved to the on position. From the foregoing description of the various elements and the manner in which they operate, it will be clear that the same type of apparatus may be adapted, where desired, to multi-pole operation and where desired, it may be possible to place two or more of the combination switch and circuit breakers side by side for multi-pole operation connecting the manual operating levers 20 by passing any suitable member through the perforation 380 (Figure 4) of adjoining manual op erating levers so that multi-pol switching may As has been above-emphasized, while this circuit breaker is useful for individual operation, the greatest utility lies in its arrangement and adaptability for panel board mounting in .th manner shown in Figure 2. l i

The lead connecting lug 30 as will be noted 55 particularly with reference to Figure 4 is protected by the curved extension 390 of the housing and is enclosed between the cover plate and this extension. The lead 45 may, ifdesired. extend from the opposite side or it may where necessary be protected in a similar manner by the extension 395 of the cover plate (Figure 1) and/or by a corresponding extension of the housing; For ordinary panel board mounting where the lead 40 is to be used as part of the support for :the

circuit breaker upon the bus it may be desirable ers of the present invention are shown mounted upon a panel board with the leads 45 connected by suitable conductive securing means, as for instance the screws 391, to a common bus 398,

s and the opposit leads connected to load wires 380 in any suitable manner. The leads 45 obviously may be sufiicient to provide adequate support for one end of the circuit breaker upon the common bus 308, although if desired any other securing means may be provided for this purpose, as for instance, the foot or lug 400 which may serve to engage a suitable clamp member upon the suppbrting base 401 of the panel or which may be extended and formed in such a manner as to provide a screw engaging means. As seen in Figure 3, flanged plate 400a may be screwed to 'thepanel and may be formed to encase foot or lug 400 to secure the same to the panel.

The foot 402 may be provided at 'the opposite end of the circuit breaker in order to Both of the lugs or feet 400 and 402 are, asseen in the figures, integral with the molded casing.

foot 402 may be provided with an open ended slot 403', thewalls of which are oriented in planes parallel to the end walls of the housing; and a recess 404' may be provided in the-upper surface of the foot 402 extending from the side opposite the open end of the slot to a point beyond the closed end of the slot for positioning the head of screw 403.

In order to insure that the circuit breaker will be perfectly level upon .the panel board support 40l, the foot 402 may be flush with the undersurface of the circuit breaker or, if this is not 40 feasible, then an additional support 405 maybe twill thus be through the common busj98 to the connecting lead through the circuit, breaker andthe' opposite lead 30' (Figure 4) and 'therefrom to the load wire 099 (Figure 3) to the mechstance to the terminal block 420 to which is connected the return wires from the individual loads: the termina block 420 being connected to the side of-the lin opposite that to which the commonbusisconnected.

Each of the individual circuits operated from each of the individual circuit breakers is thus fully'protected by its own individual circuit breaker while theentire panel board and all of the elements operated therefrom may, if desired. e protected by a single circuit breaker capable of handling the iull load. The panel which the panel board supporting member 401 is secured in anysuitable manner. The main base and mounting portion 410 may have side membersl'i'l and covering flanges 2. The covering flanges 4|! may be formed in order to support a slotted frame covering member 413:: which willconceal all of the circuit breakers except for the toi surfaces thereof at 414, 4 from which the linger grasping P rtion of the manual operating lever 20 projects. j

In this manner no part of the circuit breakers or of the panel board or of the connecting wires As may readily be seen in Figures 6 and 7, the

anism, and then 'any suitable return, as for inthe circuit; breakers are thus to be mounted closely adjacent to each other, the ends of rivets 22 may be countersunk in the molding (and bossesplaced thereabout) to provide an airspace between said rivet ends so that they will not be in contact with similar rivet ends on adjacent breakers. The rivet ends on adjacent breakers The thermal tripping means which acts in response to an overload which is not greatly excessive, but nevertheless is excessive, is slowly heated as this minor overload continues until it effects the tripping operation above described. As the overload increases the thermal element acts more and more rapidly. However, should excessive over-loads occur, then it may be danmay'then extend shghtly into the counterbore.

Such adjacent rivet ends are the ones extending from the cover plate. The cover plate is a die cut blank and the head of the rivet engages the cover plate at the rivet openings, while the op-' posite ends of the rivets in the counterbores or recesses of the molding are spun down.

Where only a thermal trip is desired without changing the structure of the device, then the core of the solenoid coil may be removed or member 245 of the core may be removed, thus leaving a dummy solenoid bushing and coil; in such case, only the thermal trip will operate. In this case also, the coil arrangement may be dispensed with,

and the braid 36 from the thermal element may be connected to a metallic tube or other pivotable element which may carry the movable contact arm. Such tube or pivotable element may rotate about an insulating tube similar to the insulating tube 23! of the solenoid.

The present circuit breaker is comprised'o'f a magnetic trip and a thermal time delay element may be incorporated in the usual form of power and light panel to handle branch circuits- The members as has been noted are readily mounted in any suitable support upon the panel and require no more space than a fused switch, and, taking into consideration the expense or replacement of fuses and the expense of operation of the fused switch, they are better than an ade-- quate substitute therefor.

They are designed to be mounted in a panel with a number of units side by side with the line terminal of each circuit breaker screwed directly to the common bus, this screw also serving to hold one end of the unit mechanically, the opposite end of the circuit breaker being mechanically supported in any suitable manner. In this manner therefore any individual units may be removed and replaced without disturbing adjoinin units.

As has been above noted the circuit breaker of the present invention is trip free in that it will open even though the handle is held in closed position and the switch cannot be held against overload or short circuit. The only way in which the circuit breaker may be reset after the interposer has been tripped is by moving the manually interposable interposer between contacts and thus maintaining the contacts in open circuit position. Should the circuit protected by the circuit breaker still be under overload conditions, then permitting the manually interposable interposer to be moved away from between the contacts will again cause the actuation of the thermal and/or solenoid elements to cause the automatically interposable interposer to move hetweenthe contacts and thus maintain the separation therebetween.

The circuit breaker, as has been noted, trips immediately upon an excessive overload owing to the operation of solenoid means above described.

gerous to allow any delay until the thermal element is sufficiently heated to accomplish the tripping operation and accordingly the solenoid tripping mechanism acts instantaneously upon greatly excessive overloads.

- Furthermore, the ability of the present circuit breaker to trip at high speed upon greatly excessive overloads would serve to prevent the main protecting circuit breaker from tripping upon the occurrence of an excessiv overload in a single branch circuit, and thus "will serve to prevent the other branch circuits operating from the same bus from being disconnected from the main circuit. a

In the foregoing description, cooperating'elements have been set forth and the interrelation therebetween has been described.

Various modifications and changes in the different parts will now be obvious to those skilled in the art. Accordingly, it is desired to be bound not by the specific disclosures herein but only by the appended claims. Y

This application is filed simultaneously with the application of Frank J. Pokorny, Serial No. 331,984, for Circuit breaker, now Patent No. 2,319,262, issued May 18, 1943; the application of William M. Scott, Jr., Serial No. 332,037, for

Circuit breaker, no-w Patent No. 2,303,959, issued December 1, 1942; and the application of Otto Jensen, Serial No. 331,967, for Circuit breaker,

now Patent No. 2,321,603, issued June 15, 1943.

In this application I have claimed those inventions and portions of the structure devised by. me.

I claim:

1. A circuit interrupter structure, a molded casing for enclosing and supporting the parts thereof, said molded casing having a side wall and other walls and members extending perpendicularly thereto, means at one end of said circuit interrupter structure for supporting said end upon a panel, and a lug integral with the molded casing extending from the other end of said casing, said lug extending from said casing and beyond the boundaries of the structure at a corner thereof and having an open ended slot tocooperate with a mounting means for securing said other end of the circuit interrupter to the panel, the walls of said slot being arranged in planes normal to the plane of said side walls.

2. A circuit interrupter structure, a molded casing for enclosing and supporting the parts thereof, said molded casing having a side wall and other walls and members extending perpendicularly thereto, means at one end of said circult interrupter structure for supporting said end upon a panel, and 9. lug integral with the molded casing extending from the other end of said oasing, said lug extending from said casing and beyond the boundaries of the structure at a corner thereof and having an open ended slot to cooperate with a mounting means for securing said other end of the circuit interrupter to the panel, the walls of said slot being oriented in planes parallel to the planes of certain of said other walls and members, and a recess in said lug in a surface thereof and extending from a side opposite the open end of said slot, and extending in angularly adjacent to said open side, the said end walls oieach-circuit breakerextending in the same plane, said cover plate extending beyond said end wall a greater distance than said terminal, said extensions of said cover plates forming interpolar barriers between adjacent similar terminals in adjacent cimmtinterrupters.

4. Ina circuit interrupter, a molded casing imenclosing and supporting the parts thereof; said casing having an open side, and a cover plate and beyond the -end said terminal and an integral extension 0! said cover plate beyond said end wall and beyond the end of said terminal,

said extensions forming insulating guards for said terminal. I

6. A circuit breaker to be mounted on a panel inclose adjacency to other similar circuit breakfor said open side; a terminal extended from an end'wall of said casing, said end wall being angularly adjacent to said open side, said cover plate extending beyond said end wall a greater distance than said terminal, said extension of said cover plate beyond said end wall being removablewhile said cover plate is in secured position over said open side oi said casing,

5. A circuitinterrupter and a molded casing 'therefor, said casing having a side wall, an opers, a molded housing having a side wall, an opposed open side and a cover thereioryrivets passing through said side wall and said cover for securing said cover in place and for cooperating in supporting members-oi the circuit breaker, the headset said rivets being countersunk in a counterbore in said side wall, the heads of rivets on the adjacent circuit breaker being nested in said counterbore with an air space between adjacent rivet heads, and bosses on said side wall around said oounterbores to increase said air space.

'I. A circuit breaker to be mounted on a panel in close'adjacency to other similar circuit breakers, a molded housing having a sidewall, an opposed open side and a cover therefor; rivets passing through said side wall and said cover for securing said cover in place and for cooperating in supporting membersoi the circuit'breaker, and means for spacing said circuit breaker from an adjacent circuit breaker moimted on said panel, said means comprising bosses on said.side wall projecting therefrom and arranged to come into contact with a side oi said adjacent circuit breaker.

HERBERT C. GRAVES, Ja.

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