US2292187A - Small automatic circuit breaker - Google Patents

Description

Aug. 4, 1942.

H. wlLLMANN SMALL AUTOMATIC CIRCUIT BREAKER Filed Jan. 12, 1939 2 Sheets-Sheet l mvENToR i Afa/fs MZZzz/m U8-I4 1942- I H. VWILLMANN 2,292,187

SMALL AUTOMTIC` CIRCUIT BREAKER I Filed Jan. 12, 1939 y 2 Sheets-Sheet 2 2,75% Insulation Patented Aug. 4, 1942 2,232,187 SMALL AUTOMATIC CIRCUIT BREAKER Hans Willmann,

Berlin-Charlottenburg,

Ger-

many, assigner to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.,

a corporation Application January 12, 1939, Serial No. 250,667

` In Germany January 12, 1938 33 Claims. A(Cl. 20G-116) The present invention relates generally to electric circuit interrupters and especially to improvements in small automatic circuit breakers.

In the manufacture of small automatic circuit breakers it has always been desirable to restrict the space requirements to a minimum so as to obtain with a given space the greatest possible interrupting capacity without impairing the reliability of operation.

An object of the present invention is to provide an improved small automatic circuit breaker which is capable of more eiiicient and reliable operation than circuit breakers of the prior art.

It is highly desirable to reduce both the weight and the lvolume of breakers of this type to a minimum. It is also important that the circuit breaker be as shock-proof as possible. Furthermore, it must fulfill electrical requirements of a more exacting character than the usual automatic circuit breakers particularly where the breaker is installed so as to be exposed to the action of fog and rain.

To render a circuit breaker shock-proof to the desired extent it has proved particularly advantageous to effect the release of the contacts of such automatic circuit breakers by a currentheated bimetallic strip, supported at its ends and having the central portion thereof control a latch for a lever which is under the influence of an interrupting spring. In order to maintain a predetermined current-time characteristic of the release, such a releasing member must be properly dimensioned, particularly as to length, since otherwise it would be very diflicult to attain the predetermined releasing characteristic,

In the small automatic circuit breakers hitherto proposed, provided with a releasing member of the above-indicated character, the bimetallic strip was, as a rule, arranged in parallel relation to the base plate of the circuit breaker. For such circuit breakers the length necessarily was predetermined by the minimum length of release member.

According to my invention, I am able to reduce the dimensions and weight of a small automatic circuit breaker despitev the use of a releasing member of the above-indicated character having the required relatively large dimensions, by arranging the bimetallic strip inclined with respect to the base plate of the circuit breaker so that it forms together with the base plate and the switching gap between the open contacts a substantially rectangular triangle. Such a design of the circuit breaker is of great advantage as compared to that of the circuit breakers hitherto known, particularly in view of the reduction of the length of the circuit breaker as well as tending to permit of more favorable wiring conditions within the same.

Another object of my invention is to provide a novel arrangement of the essential parts of a circuit breaker into a smaller space for a given size of breaker than has heretofore been possible.

Another object of my invention is to provide a novel arrangement of circuit breaker operating mechanism to occupy a less space than has heretofore been possible while at the same time providing space for the mounting of circuit breaker accessories.

Another object of my invention is to provide novel supporting means for circuit breaker contacts and operating mechanism wherein the contacts are insulated from the operating mechanism.

Another object of my invention is to provide novel supporting means for supporting the contacts and operating mechanism of Ya circuit breaker as a unit for ready attachment to or detachment from a mounting base which carries other parts of the circuit breaker independently, with respect to the said unit.

Another object of my invention is to provide a novel type of operating mechanism for a circuit breaker which is relatively simple in form yet eflicient in operation and having but small space requirements.

A further object of my invention is to provide a circuit breaker operating mechanism, the manual operating member of which is automatically resettable in a novel manner following an automatic interrupting operation of the breaker.

Still another object of my invention is to provide a novel circuit breaker contact structure which is adapted to provide a wiping action of the contacts at each operation thereof.

These and other objects of my invention will become more apparent upon consideration of the following detailed speciiication of a preferred embodiment thereof taken in connection with the attached drawings, in which:

Figure 1 is a diagrammatic view of a circuit breaker operating mechanism including circuit breaker contacts constructed in accordance with my invention,

Fig. 2 is a View similar to Fig. l but showing the breaker contacts in the open position immediately prior to the automatic resetting cf the manually operable button 24,

Fig. 3 is a View similar to Figs. 1 and 2 showing the final open position of the parts with the manually operable control member 24 in a position in which it is adapted to be operated to reclose the breaker contacts,

Fig. 4 is a side View of a circuit breaker constructed in accordance with my invention and embodying the linkage mechanism illustrated in Figs. l, 2, 3 with a portion of an outer wall of the breaker broken away to more clearly illustrate some of the parts, and with the contacts and mechanism in the same position as in Fig. 3,

Fig. 5 is ak top View of the circuit breaker shown in Fig. 4,

Fig. 6 is an end view of the circuit breaker shown in Figs. 4 and 5 looking at the right-hand end of the circuit breaker as shown in these gures,

Fig. 7 is a longitudinal sectional view of the circuit breaker shown in Figs. 4 to 6 and illustrating the breaker contacts and operating mechanism in a position corresponding to that shown in Fig. 2,

Fig. 8 is a view similar to Fig. 7 but showing the breaker contacts in their closed position,

Fig. 9 is a side view of the manual control button for reclosing the circuit breaker shown in Figs. 4 to 8 and showing in cross section a guide member therefor.

For a better understanding of the invention reference is made in the following description, particularly to Figs. 1 to 3 of the accompanying drawings in which the operating mechanism of the circuit breaker is diagrammatically shown. The stationary parts of the circuit breaker as well as the terminals, current-carrying parts, releasing members and the springs necessary for bringing about the contact pressure are omitted in these figures.

Fig. 1 shows the arrangement in the closed position. I is a stationary contact and II a movable contact which is mounted onto one arm of a bell crank I3 pivoted at I2 on the circuit breaker base 26. The other arm of the bell crank I3 is connected to one end I5 of a toggle link I6 of the circuit breaker operating mechanism through an insulating link I4 pivotally connected to the bell crank lever I3 and to the toggle link I6. The end I of the toggle link I6 is connected with an actuating link I8 rotatably mounted on the base 26 as indicated at 31. The link I 8 is biased to move in a clockwise direction as seen in Fig. 1 by an interrupting spring I9. A second toggle link I1 is pivoted to the other end of toggle link I6 and the end 20 of the toggle link I1 is hinged to the short arm of a bell crank lever 122 rotatably mounted as indicated at 2|, the long arm of which is in the form of a latching lever cooperating with a long-armed pawl 23 which is adapted to be actuated by releasing members (not shown). A push button 24 which acts on the knee of the toggle by means of a guide slot 6I serves to insert the switch in the circuit. The lower end of push button 24 is supported on the base 26 so that movement of the knee of the toggle is limited in the downward direction.

The arrangement operates as follows:

If the pawl 23 shown in Fig. 1 in the closed position is moved to the left by means of automatic or hand-operated releasing members, the latching lever 22 and therefore the interrupting spring I9 are released. In this case the contact II is brought into the open position and the latching lever 22 is rotated counter-clockwise, while the relative position of the toggle links I6, I1 remains unchanged, i. e., the arrangement assumes the position as shown in Fig. 2. A lifting spring (not shown) is provided which upon the release of the latching lever becomes effective and causes the knee of the toggle links to move in the upward direction so that the push button 24 is brought into the open position shown in Fig. 3 and the latching lever 22 is brought again into engagement with the pawl 23. The pawl 23 is always under the action of the spring I9 or another force which tends to move it in the clockwise direction. From the position shown in Fig. 3 the circuit breaker can again be inserted in the circuit by depressing the push button 24 to the position shown in Fig. 1.

Owing to the peculiarity of such an operating mechanism of the circuit breaker a relatively long switching path may be attained with a very compact arrangement of parts, particularly with the aid of a bell crank lever-shaped contact carrier arranged in the neighborhood of the switching point. A satisfactory insulation of the movable mechanism parts may be attained by means of the relatively long link I4 of insulating material, despite the very compact arrangement of the constructional parts. The transmission of the interrupting force from the spring I9 to the Contact II through the pair of toggle links I6, l1 renders possible a uniform distribution of the counter-pressure forces over the entire switching path, as well as a smooth reliable switching-in operation even in the case of a very strong interrupting spring. The manner in which the arrangement is supported in the closed position on the stationary part 26 renders the circuit breaker highly insensitive to a rough handling, for instance, when unduly stressing the switching-in member 24 during the switching operation, this stress will be entirely taken by the switching-in member which may be of a very robust construction; furthermore, the stationary part 26 may be of a material capable of absorbing great forces, and it should be noted that no joints or bearingsv are stressed when the switch is closed.

The other gures of the drawings show various views of an automatic circuit breaker according to my invention which construction is substantially the same as that shown diagrammatically in Figs. 1 to 3, with like numerals being employed to designate like parts.

IOn the base plate 26 of the circuit breaker which may consist of metal, preferably a light sheet metal, are arranged two upright supporting walls 21, 28 (Fig. 6). Between the latter are supported the toggle links I6, I1, the bell crank lever I3 controlled by the toggle links through the insulating link I4, and the contacts I 0, II f Figs. '1, 8). The bell crank lever I3 is generally triangular in shape and is pivoted at one corner on Ipin I2 mounted in, and bridging walls 21 and 28, and carries at another corner the movable contact supporting arm 46, and is pivotally connected at its third corner with one end of link I4. The other end of link I4 is in turn pivoted by pin I5 to the upper end of actuating lever I8, and to one end of toggle link I6. The actuating lever I8 is pivoted at its lower end on pin 31 secured between side walls 21 and 28, and the other end of toggle lever I6, is pivoted to one end of toggle lever I1 by a pivot pin 65 the ends of which are guided for horizontal movement in a slot 6I provided as a part of push button 24. The other end of toggle lever I1 is pivoted to the short leg of bell crank lever 22 pivotally mounted between `the walls 21 and 28., as by the pivot pin 2|. Outside of the supporting walls are arranged on one side the bimetallic strip 29 and on the other side the levers 22, 23 of the latch means (Figs. 4 to 6).

vThe latch lever 23 (see Fig. 5) forms one leg of a generally U-shaped lever, pivoted on the pin 31, with the legs thereof outside of supporting walls 21 and 28, and with the other leg 32 thereof carrying an insulating block 3|. The block 3| in turn carries a bifurcated control member 30 engaging with substantially the mid .portion of the inclined self heated bimetallic release member 29 which is received between the bifurcations of member 30 to thereby completely protect the bimetal member 29 from being in fluenced by the heat of the other current-carrying parts. The long leg of bell crank lever 22 extends along the outer side of wall 28 into cooperative relatio-n with respect to latch lever 23.

The base 26 has a sheet of insulating material 62 overlying the same and also carries at one end thereof an insulating block 45 -Which supports a pair of breaker terminals 33 and 43. The terminal 43 is connected by a conducting strip 4| and ilexible shunt 40, with the movable contact Terminal 33 has secured thereto an angled conducting strip 34 extending to the lower terminal of the bimetal element 29. The other terminal 35 of the bimetal element is connected through wall 21 to the fixed contact l0.

The circuit through the breaker extends from the terminal 33 to the xed contact I0 through angle bar 34, bimetallic strip 29, sup-port 35 for the upper end of the bimetallic strip, xed contact and then to the other terminal 43 through the movable contact Il, its flexible conductor 40, and angle bar 4|.

As previously described, latch lever 23 is substantially U-shape in form and the cross portion thereof 53 is adapted to be engaged by release push button to release the lever from pawl 22, also the latch lever 23 is adapted to be actuated by bimetal stri-p 29 which, upon passage through the breaker of currents above a predetermined value, will have the mid-portion thereof deflected upwardly to move the latch lever 23 counterclockwise as viewed in the drawings. Release of the latch lever 23 causes the contacts to open and toggle links I6, |1 to be moved to the position shown in Figs. 3 and 4 of the drawings, and this carries push button 24 to an extended position as shown. To reclose the contacts and reset the latch mechanism, it is merely necessary to depress push button 24 as far as possible to thereby move the toggle links past their dead center position.

With a triangular arrangement of the releasing member 29, switch base plate 26 and switching gap as shown in Figs. 4 to 8 the contacts may be advantageously arranged in the neighborhood of one of the side walls of the switch with one above the other in such a manner that when opening the circuit the arc may be moved outwardly under the action of a blowing force, in a direction away from the operating mechanism of the switch.

Since the lower contact is designed as a mov-- able contact and the upper contact as a fixed contact, the space within the triangular arrangement is properly utilized by the movable contact, its movable carrier and by the immediate driving parts thereof. Also an undesirable additional heating of the releasing member by the conductors leading to the movable contact is thus prevented.

The space at the left above the releasing member 29 (Fig. 4) may be utilized for accommodating any desired circuit breaker auxiliary device such as an electromagnetic current indicating device (not shown). y

In the space below the base plate of the switch is arranged a shunt resistance 42, one end of which is connected to the angle bar 34 and the other end thereof to a connecting angled conducting member 44 extending in the upward direction from the base plate. This connecting angled member is conductively connected to the upper end of the bimetallic strip and is preferably integral with the support 35. The wiring within the switch is therefore very simple, since the bimetallic strip 29 and the shunt resistor 42 are utilized for bridging the longest distances in this circuit breaker, and in this manner undesirably long wire loops are eliminated.

The shunt resistance being preferably arranged in the hollow space of the base plate is therefore easily replaceable without it being necessary to remove any of the switch operating parts. Furthermore, a particularly favorable dissipation of heat may be attained when arranging the shunt resistance in the base plate.

The supporting walls 21 and 28 of the switch consist partly of metal, preferably a light metal,`

and partly of plates of insulating material. These different parts of each wall are directly placed one upon the other in side by side relation but project from one another at some points. Thus the plates of insulation project to the right and the metal plates project to the left, as viewed in Figs. 4, 5, 7 and 8. The metal parts form a frame Which reenforces the entire arrangement. Spanning and rigidly secured to both of the metallic side wall parts is also arranged a transverse wall 25 which serves as an end stop for the switching-in member 24 as shown in Fig.r9 and also as a guide therefor. All external forces acting on the switch and its actuating member are absorbed by the metallic parts of the frame. In the plates of insulating material are preferably arranged the parts of the switch under tension, i. e., the pivot pin |2 of the movable contact and also the carrier 35 of the stationary contact. By providing the metallic wall parts with suitable enlarged apertures aligned with the ends of pivot pin B, special precautionary measures for the insulation of current-carrying bearing points need not be taken.

v- The insulating parts of the walls 21 and 28 on opposite sides of the switching gap may preferably at the same time serve as lateral walls of the spark chamber. However, if desired a separate insulating lining may be provided at this point.

The upper parts of the supporting walls 21, 28 are connected with each other by at least one transverse wall 59. This transverse wall serves as a further reenforcement of the structure and as a guide for the switching-in push button 24 and the switching-out push button 5|. Such a guide of the actuating members by parts of the supporting structure itself has the advantage that the operating mechanism of the switch operates smoothly and properly and may be for certain applications employed without an outer hood which is usually employed in small automatic circuit breakers as a guide for the switching-in member. It is, for instance, also possible to arrange a plurality of switches in the form of a battery and to provide them with a common cover which may consist of sheet metal or insulating material.

The extensions 36 of the transverse wall 50 project through apertures in the supporting walls 21, 28, The ends of the extensions may be upset on the outer side of the wall, and the walls may be also held together by the upset outer ends of the pivot pins.

In a similar manner the lower edges of the metal parts and insulating parts of the supporting walls 21, 28 are provided with lugs 63 which engage in recesses of the metal base plate. The support plates 21, 28 and therefore the entire upper part of the circuit breaker are rmly secured to the base 26 by means of a bolt 38. The latter is screwed in a transverse piece 39 which may extend through both lateral walls 21, 28, or as shown, only through one of the same (21) and through a third lateral wall 21'. A tie member 64 is provided for tying wall 21 to wall 21. The operating mechanism therefore forms together with the frame a unit independent of the base plate which may be easily removed from the base plate after loosening the bolt 38 in order to facilitate certain manipulations which may be nec essary, for instance, for calibrating the circuit breaker.

Particularly the construction of the supporting `frame as well as the support of the actuating members through the frame itself, and the arrangement of the current carrying parts, i. e., their support solely by the insulating parts of the walls consisting of metal plates and plates of in* sulating material, is of special advantage in the construction of circuit breakers.

The contact supporting part 46 arranged between the supporting walls 21, 28 and on which the movable contact Il is secured preferably by rivets or the like with the eXible copper conductor 46 inserted between contact II and support 46, is pivotally mounted on the bell crank lever I3 and a strong contact pressure spring 41 is provided for normally biasing support 46 for counterclockwise movement relative to bell crank I3 in order to produce the contact pressure necessary in the closed position of the contacts. The movement of contact support 46 under the inuence of the contact pressure spring is limited by an extension 48 on the support 46, which in the open position of the contacts comes into engagement with the pivot pin I2 of the bell crank lever I3 so that the contact pressure spring 41 is in a stressed condition in the open position of the contacts. The bell crank lever I3 and the support arm 46 to which is secured the movable contact II are so dimensioned and arranged according to the invention that both contacts, which are cambered or provided with convex surfaces as shown, are, upon closing of the contacts pressed against each other and at the same time are shifted under pressure relatively to each other. In this manner the contacts when switching in and out are on the one hand automatically cleaned in a novel manner, and on the other hand such a push-pull contact motion according to my invention provides for contact pressures predetermined by spring 41.

The interrupting member 5I, the upper end of which is arranged in the transverse wall 50 and whose movement in the downward direction is limited by a transverse web 60, is provided, in order to dispense with a lower guide, at its lower part 52 which acts on an integral extension 53 of the pawl 23, with a slot 54 in which is slidably received the shaft 31 for guiding the lower end of interrupting member 5I. The shaft 31 also supports the link I8, on whose end I5 the toggle lever I6 and the insulating control lever I4 are pivotally mounted, as well as the control spring I9. In this manner a saving in space, material and also in weight is attained, since separate means for supporting these different constructional parts are not necessary.

The lifting spring which as above mentioned in connection with the description of the operation of the switch mechanism, moves the toggle into the collapsed position in the upward direction upon the release of the latch parts 22, 23 and therefore brings the switching-in member into the open position and causes the part 22 to engage again with the pawl 23, so that the switch is again ready to be switched in again, as is shown in Fig. 4. The return spring is denoted in Fig. 8 by the reference numeral 65, and is coiled on the pivot pin I5 and reacts between toggle lever I6 and lever I8. When the circuit breaker is switched in as shown in Fig. 8, the spring is stressed but it cannot move the knee of the toggle towards the collapsed position in the upward direction, since the extension 56 on the bell crank lever 22 engages in this position with an abutment on wall 21 to prevent such a movement. The lifting spring 55 can only become effective to bring the button 24 into the open position shown in Figs. 3 and 4, after the latching lever 22 has been released, i. e., after the breaker mechanism has assumed the position as shown in Figs. 2 and '1.

From the foregoing, it should be obvious that I have provided a novel circuit breaker construction having a novel arrangement of bimetallic strip which is supported at both ends diagonally with respect to the circuit breaker base so as to form with the line of action of the circuit breaker contacts and the base, a substantially right angle triangle. The circuit breaker mechanism is mounted in part within the connes of this triangle and in no event extends a greater distance from the base than the end of the bimetal element which is more remote from the base. Such a construction also permits the mounting of circuit breaker terminals at one end of the base leaving a space thereabove which can be utilized for the mounting of any desired circuit breaker accessory.

It should also be apparent that I have provided a contact construction incorporating a predetermined contact pressure together with a wiping action of the contacts when they are moved into or out of engagement. The circuit breaker disclosed herein embodies novel supporting means including the unit construction and support of the contacts and operating mechanism between spaced supporting plates which are partly of insulating material to electrically isolate the contacts from the remainder of the mechanism, and which unit is provided with positioning means engageable with apertures in the base to properly position the unit with respect to the base, and with means for the detachable securement of the unit with respect to the base. It should also be noted that the insulating portions of the spaced supporting plates for the circuit breaker contacts and operating mechanism also forms an arcing chamber for the contacts. Another novel feature of my invention resides in the segregation of the conducting and heating elements of the breaker. That is, the self-heating bimetallic strip is segregated by the partition wall 21 from.

the remainder of the operating mechanism contacts and current carrying parts. Likewise, the resistor 42 is mounted beneath the supporting base of the breaker to be isolated from all of the other parts of the breaker.

What is claimed is:

1. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip associated with said mechanism for automatically releasing said mechanism tc open said contacts, said strip including means for supporting the strip along the greatest dimension of said mechanism, and the length or said strip being substantially equal to said greatest dimension.

2. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip associated with said mechanism for automatically releasing said mechanism to open said contacts, said strip including means for supporting the strip along the greatest dimension of said mechanism with said strip being spaced from one end of said base and being of a length substantially equal to said greatest dimension.

3. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip associated with said mechanism for automatically releasing said mechanism to open said contactsJ said strip including means for supporting the strip along the greatest dimension of said mechanism with the length of said strip being substantially equal to said greatest dimension, said strip and mechanism being spaced from one end of said base, and terminals for said breaker at said one end of said base.

4. In a circuit breaker having a base and separable contacts thereon, a bimetal strip for controlling relative movement of said contacts, means supporting said strip on said base at an angle thereto, and said contacts being so constructed and arranged on said base that the switching movement thereof is located substantially on a line between said base and the end of said strip more remote from said base.

5. In a circuit breaker having a base and separable contacts thereon, a bimetal strip for controlling relative movement of said contacts, means supporting said strip on said base at an angle thereto, and said contacts being so constructed and arranged on said base that the line of switching movement thereof is located so as to be at least tangent to a line which forms with said base and strip a substantially right angle triangle and having its base along said breaker base.

6. In a circuit breaker, a substantially fiat base member, a skirt on said member for supporting one side of said member in spaced rela.- tion with respect to a supporting surface, relatively movable contacts oarried by said base member, latch mechanism for maintaining said contacts closed, current responsive means for releasing said latch mechanism to permit said contacts to open, and a resistor mounted on said base and located in the space beneath the said one side of said member so as to be concealed by said skirt, and said resistor being connected in shunt relation to said current responsive means.

'7. In a circuit breaker, a supporting base therefor, relatively Xed and movable contacts, means supporting said contacts on said base so that said movable contact is movable into and out of engagement with respect to said xed contact, said supporting means including a bell crank pivotally supported with respect to said base, and pivotally carrying said movable contact, resilient means biasing said movable contact about its pivot toward said fixed contact to provide predetermined contact pressure in the closed circuit position, cooperating stop means on said movable contact and bell crank for limiting said biasing movement, said stop means being arranged so that said resilient means is under a substantial stress in the open position of said contacts, and operating mechanism for said movable contact operatively associated with said bell crank.

8. In a circuit breaker, a supporting base therefor, relatively fixed and movable contacts, means supporting said contacts on said base so that said movable contact is movable into and out of engagement with respect to said fixed contact, said supporting means including a bell crank pivotally supported with respect to said base, and pivotally carrying said movable contact, resilient means biasing said movable ccntact toward said fixed contact to provide predetermined contact pressure in the closed circuit; position, operating mechanism i'or said movable contact operatively associated with said bell crank, and said contacts having opposed engaging surfaces whereby relative wiping movement of said engaging surfaces is produced upon engagement and disengagement of said ccntacts.

9. In a circuit breaker, a supporting base therefor, relatively iixed and movable contacts, means supporting said contacts on said base so that said movable contact is movable into and out of engagement with respect to said iixed contact, said supporting means including a bell crank pivotally supported with respect to said base, and pivotally carrying said movable contact, resilient means biasing said movable contact toward Said fixed contact to provide predetermined contact pressure in the closed circuit position, operating mechanism for said movable contact operatively associated with said bell crank, and said contacts having opposed conveX engaging surfaces whereby relative wiping movement of said engaging surfaces is produced upon engagement and disengagement oi said contacts.

10. In a circuit breaker, relatively mov contact means for controlling the circuit throng the breaker, mechanism controlling the opening and closing of said contact means including toggle means movably mounted at both ends thereof, one end of said toggle means being connected to said contact means through a bell crank lever, a guide for the knee of said toggle means, means biasing said mechanism in a manner to open said contact means, latch means normally opposing movement of said toggle means under the influence of said biasing means, and means for releasing said latch means to permit said biasing means to operate said mechanism to open said contacts.

l1. In a circuit breaker, relatively movable contact means for controlling the circuit therethrough, mechanisms controlling the opening and closing of Said contact means including toggle means movably mounted at both ends thereof, one end of said toggle means being connected to a bell crank lever carrying one of said contact means by a pivoted link, a guide for the knee of said toggle means, means biasing said mechanism in a manner to open said contact means, latch means normally opposing movement of said toggle means under the influence of said biasing means, and means for releasing said latch means to cause said contacts to open the circuit under the influence of said biasing means.

12. In a circuit breaker, relatively movable contact means for controlling the circuit therethrough, mechanism controlling the opening and closing of said contact means including toggle means movably mounted at both ends thereof, one end of said toggle means being operatively associated with said ycontact means, and the -f other end thereof being operatively associated with a latch lever, pawl means for releasably engaging said latch lever, a guide for the knee of said toggle means, means biasing said mechanism in a manner to open said contact means, means for releasing said pawl means to cause said contacts to open the circuit, said toggle knee guide bein-g movably mounted and manually operable in one direction past its overcenter position to close said contact means, stop means for limiting movement of said guide in said one direction to maintain said contact means closed, means biasing said guide for movement in the opposite direction to reset said pawl means andv latch lever following an interrupting operation,

and stop means positioned to prevent movement of said guide in said opposite direction when said contact means are closed.

13. In a circuit breaker, separable contact means for controlling the circuit therethrough, actuating means including toggle mechanism for controlling the opening and closing movements of said contact means, a plurality of spaced supporting plates for said means and between which said means are mounted, a frame member bridging the space between a pair of said plates for forming a rigid frame structure therewith, control means slidably mounted in said frame member and including a guide for a pivot of said toggle mechanism to move the same past an overcenter position, and said frame member cooperating with a portion of said control means to limit movement thereof in the direction of said movement ,of said toggle mechanism past said overcenter position.

14. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures each of which includes a portion of insulating material, said contact means being mounted on said insulating plate portions, and means insulating said mechanism from said contact means.

15. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures of laminated construction, with at least one lamination thereof being of an insulating material projecting beyond the remainder of its respective plate structure for supporting said contact means, and means insulating said mechanism from said contact means.

16. In a circuit breaker, separable contact means for controlling the circuit therethrough, actuating means including toggle mechanism for controlling the opening and closing movements of said contact means, releasable latch means for said toggle mechanism, a plurality of spaced supporting plates for said means and between which at least a portion of said means is mounted, bridging means connecting said plates to form a rigid frame, control members slidably mounted in said bridging means and projecting from said plates for controlling said toggle mechanism and latch means, respectively.

17. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures, bridging frame means connecting said plates to form a rigid supporting unit, a base for said unit, complementary positioning means on said base and unit, and means for detachably securing said unit to said base; said base supporting terminals for said circuit breaker independently of said unit.

=18.111 a circuit breaker, relatively movable contact means for controlling the circuit therethrough, means controlling the opening and closing of said contacts including toggle means movably supported at opposite ends thereof by supporting links, one of said supporting links being operatively connected to said contact means, the other of said supporting links comprising a bell crank having a short arm supporting said toggle means and a long arm, said long arm extending along said toggle means and being of a length at least equal to the length of one of the levers of said toggle means, said long arm having a latch portion extending into at least a portion of the path of movement of an elongated pawl member to lock said toggle against substantially longitudinal movement, means biasing said toggle for substantially longitudinal movement, means for releasing said pawl from said latch to permit longitudinal movement of said toggle to open said contact means, means engaging said toggle effective to collapse the same when said contacts are open to reset said latch portion in engagement with said pawl member, and control means operable to thereafter reset said toggle to close said contact means.

19. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures for supporting said contacts and operating mechanism therebetween, and thermally responsive means for controlling said mechanism mounted at the outer side of one of said plates.

20. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip arranged so as to be responsive to currents above a predetermined value for automatically releasing said mechanism to open said c-ontacts, said strip including means for supporting the strip at one side of and along the greatest dimension of said contacts and mechanism with the length of said strip being substantially equal to said greatest dimension.

21. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip arranged so as to be responsive to currents above a predetermined value and supported at opposite ends thereof along the greatest dimension of said mechanism and contacts, said mechanism including a part engageable with a portion of said strip intermediate opposite ends thereof to be actuated thereby to open said contacts in response to currents above a predetermined value. i

22. In a circuit breaker, relatively movable contact means for controlling the circuit therethrough, mechanism controlling the opening and closing of said contact means including toggle means movably mounted at both ends thereof, one end of said toggle means being connected to a bell crank lever by a pivoted link of insulation material, said bell crank lever carrying one of said contact means with said bell crank located adjacent said one c-ontact means, a guide for the knee of said toggle means, means biasing said mechanism in a manner to open said contact means, latch means normally opposing movement of said toggle means under the iniiuence of said biasing means, and means for releasing said latch means to cause said contacts to open the circuit under the inuence of said biasing means.

23. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures each of which includes metallic portions for supporting said mechanism land a portion of insulating material, said contact means being mounted on said insulating plate portions and positioned so as to be separable between said insulating plate portions so that the arc will be laterally confined thereby, and means insulating said mechanism from said contact means.

24. In a circuit breaker, separable contact means for controlling the circuit therethrough, actuating means including toggle mechanism for controlling the opening and closing movements of said contact means, releasable latch means for said toggle mechanism, a plurality oi spa-:ed supporting plates for said means and between which at least a portion of said means is mounted, frame members extending between said plates to form with said plates a supporting unit, said frame members including reduced extensions adapted to be received in correspondingly shaped apertures in said plates to be secured thereto.

25. In a circuit breaker including a separable contact means and operating mechanism therefor, unitary supporting means for said contact means and operating mechanism, a base for said unit having terminals thereon, cooperating lug and recess positioning means on said unit and base, respectively, and a single means for securing said unit in operative relation on said base.

26. In a circuit breaker, separable contact means for controlling the circuit therethrough, actuating means including toggle mechanism for controlling the opening and closing movements of said contact means, releasable latch means for said toggle mechanism, a plurality of spaced supporting plates for said means and between which at least a portion of said means is mounted, means including at least one pivot pin supporting said mechanism on said plates,

and a control member therefor slidably mounted on said pin.

27. In a circuit breaker, separable contact means for controlling the circuit therethrough, actuating means including toggle mechanism for controlling the opening and closing movements of said contact means, releasable latch means for said toggle mechanism, a plurality of spaced supporting plates for said means and between which at least a portion of said means is mounted, bridging means connecting said plates to form a rigid unit, means including at least one pivot pin supporting said mechanism on said plates, and a control member therefor slidably mounted on said pin and bridging means.

28. In a circuit breaker including separable contact means and operating mechanism therefor, supporting means for said contact means and operating mechanism including a plurality of spaced supporting plate structures for supporting said contacts and operating mechanism therebetween, latch means mounted at the outer side of one of said plates for releasably locking said mechanism in a position corresponding to the closed position of said contact means, and current responsive means for releasing said latch means mounted at the outer side of the other of said plates.

29. In a circuit breaker, relatively movable contact means for controlling the circuit therethrough, means controlling the opening and closing of said contacts including toggle means movably supported at opposite ends thereof by supporting links, one of said supporting links being operatively connected to said contact means, and the other of said supporting links comprising a bell crank having a short arm supporting said toggle means and a long arm having a latch portion extending into at least a portion of the path of movement of an elongated pawl member to lock said toggle against substantially longitudinal movement, said pawl member being supported on the pivot support of said one supporting link, means biasing said toggle for substantially longitudinal movement, means for releasing said pawl from said latch to permit longitudinal movement of said toggle to open said Contact means, means engaging said toggle effective to collapse the same when said contacts are open to reset said latch portion in engagement with said pawl member, and control means operable to thereafter reset said toggle to close said contact means. i

30. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip associated with said mechanism for automatically releasing said mechanism to open said contacts, said strip including means for supporting said strip so that it eX- tends substantially diametrically with respect to said mechanism and substantially coextensive therewith.

31. In a circuit breaker having a base and separable contacts thereon, mechanism for causing relative movement of said contacts into and out of engagement with respect to each other, a bimetallic strip associated with said mechanism for automatically releasing said mechanism to open said contacts, said strip including means for supporting said strip at an inclination to said base and with said contacts and mechanism substantially confined between said base and a plane parallel with said base passing through the end of said strip which is more remote from said base, and between planes perpendicular to said base passing through the opposite ends of said strip, respectively.

32. A circuit breaker comprising a pivoted switch arm, operating means therefor comprising a pivoted latching lever, a holding lever for releasably restraining said -latching lever in one position, a toggle connected at one end to said latching lever and at its other end to the switch arm, an operating member for moving the knee pivot of the toggle to cause movement of the switch arm to closed circuit position, a manually operable tripping member for moving said holding lever to release the latching lever and thereby cause opening of the breaker, and a bimetal element heated in response to the current of the circuit for moving said holding lever to eiect release of said latching lever in response to predetermined overload conditions, said holding lever having three arms, one of said arms being engageable with the latching lever to restrain said latching lever, another of said arms cooperating with said bimetal element, and the third arm cooperating with said manually operable tripping member.

33. A circuit breaker comprising relatively movable contacts, operating means therefor comprising a manual operating member operable to close said contacts, a member releasable to cause opening of said contacts, a holding lever for restraining said releasable member, a manually operable tripping member for moving said holding lever to release Said releasable member, and a bimetal element heated in response to the current of the circuit and operable in response to predetermined overload conditions to move said holding lever to effect release of said releasable member, said holding lever having three arms, one of said arms being engageable with the releasable member to restrain said member, another of said arms cooperating With said bimetal element, and the third arm cooperating with the manually operable tripping member.

HANS WILLMANN.

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