US2130369A - Automatic circuit breaker - Google Patents

Description

Sept. .20, 193 3- vF. M. CHRISTENSEN 2,130,369

AUTOMATIC C IRCUIT BREAKER Filed Sept. 9, 1957 2 Sheets-Sheet l F151 F15. 2 F195 2Q LIT/UN ffy. 5 F137. 5

Sept 20, 1938 P. IM. cHRlsTENsEN 2,130,369

lAUTOMATIC CIRCUIT BREAKER Filed Sept. 9, 1937 2 Sheets-SheetI 2 F1377. 7 Fly. 5

Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE AUTOMATIC CIRCUIT BBEAKEB Company. Hartford, Connecticut Conn., a corporation of Application September 9, 1937, Serial No. 163,114

C'laims.

As concerns one of its phases, this invention relates particularly to a circuit breaker of the type disclosed in the patent to Joseph Sachs, No. 1,812,843, dated June 30, 1931. In a circuit breaker of this type there is provided at least one stationary or rupture contact, a movable contact member carrying at least one movable contact adapted to engage the rupture contact, an actuator movably connected with the contact member, an electro-responsive latch bodily movable wth the contact member and normally connecting it with the actuator for movement in unison therewith, and an operating means, as for instance toggle links, connected with the actuator for moving or holding it and for thus moving or holding the contact member.

As disclosed in the said patent the latch engages directly with the actuator, and it has been heretofore proposed,v in the co-pending application of Joseph Sachs for Automatic circuit break-y er, Serial No. 160,249, filed August 2l, 1937, to provide a. modified construction wherein the latch engages a movable trip member which is separate from the actuator but which is normally mechanically connected thereto for movement in unison therewith. This last mentioned construction makes it possible for the actuator and the latch to be each located in the most advantageous relationship to the contact member; and the said construction makes it possible for the major portion of the necessary force for moving or holding the contact member to be transmitted directly to the contact member independently of the trip member and latch.

In accordance with the present invention there is provided a separate trip member as above mentioned, but the parts are so related that the trip member upon being released by the latch moves only a small distance and then entirely releases the actuator which moves independently to permit circuit-opening movement of the contact member. By this arrangement I avoid excessive movement of the trip member and also very greatly reduce the force transmitted to the latch. Other advantages will appear from the detailed description hereinafter presented.

As concerns another phase of the invention, I do not necessarily limit mysef to a circuit breaker of the type disclosed in the said Sachs patent. In accordance with this phase of the invention the mechanism of the circuit breaker is enclosed in a housing comprising two sections having thedivision plane between them parallel with the plane of movement of the contact member. The sections preferably constitute the sole guiding (Cl. 2ML-116) and supporting means for the movable parts of the circuit breaker, and the said sections are preferably duplicates of each other. Further advantages incident to the sectional housing will be pointed out in the detailed description.

In the accompanying drawings a suitable embodiment of the invention is shown, but it will be understood that the drawings are intended for illustrative purposes only and are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

Fig. 1 is a front view of a circuit breaker embodying the invention, the handle being in the closed-circuit position.

Fig. 2 is a vertical sectional view taken along the line 2--2 of Fig. 3.

Fig. 3 is a side view oi' the circuit breaker with one section of the housing removed, the parts being in closed-circuit positions.

Fig. 4 is a bottom view of the circuit breaker partly in section along line 4 4 of Fig. 1.

Fig. 5 is a horizontal sectional view taken along the line 5 5 of Fig. 3 but showing both sections of the housing.

Fig. 6 is a horizontal sectional view taken along the line 6-6 of Fig. 3 but showing both sections of the housing.

Fig. 'I is a view similar to Fig. 3 but showing the parts in open-circuit positions. In this view the mechanism is shown partly in section along a line corresponding to the line 1-1 of Fig. 5.

Figs. 8, 9 and 10 are views similar to Fig. '7 but showing the parts in different relative positions.

In describing the circuit breaker as shown in the drawings, I will first describe the principal parts of the circuit breaker mechanism referring only briefly to the enclosing housing. Thereafter the housing will be described in greater detail. As shown, the housing is made in two sections and serves as the sole means for guiding and supporting the circuit breaker mechanism.

At least one stationary or rupture contact I is mounted within the housing near the rear thereof, this contact being carried by a resilient conductor 2. Preferably, and as shown, there is a second stationary or rupture contact 3 carried by a resilient conductor i. The contacts I and 3 with their conducting supports are similar to each other and are spaced apart vertically. The contacts I and 3 are substantially stationary, that is, they are not movable to any substantial extent but only to the very limited extent permitted by the resiliency of the conductors 2 and l. For

convenience the said contacts I and 3 will be herein designated as rupture contacts.

Mounted within the housing is a contact carrying member 5, which as illustrated comprises two insulating plates 5*, 5EL spaced apart transversely. Although the invention is not necessarily so limited, the contact member 5 is shown as being rectilinearly movable forward and rearward.

Extending transversely between the insulating side plates 5, 5a -are two metallic strips or plates 6 and 'I, these having lugs 6, 6e and 1, 7B at their ends which project through suitable holes in the plates 5H, 5 and are riveted over. Carried by the respective plates 6 and 'I between the side plates 5a, 5a are movable contacts 8 and 9 which are adapted to engage and disengage the respective stationary -or rupture contacts I and 3.

The contact member 5 is biased for movement in the circuit-opening or contact disengagin'g direction, that is in the forward direction, and as shown such biasing is effected by means of springs i0, IIJ connected with the side plates and positioned adjacent the outer sides thereof. The details of construction and mounting of these springs will be set forth in greater detail hereinafter.

An actuator II is provided which is connected with the contact member 5 so as to be movable relatively thereto and so as to be also bodily movable therewith. The actuator may be variously constructed, but it is shown as being of lever form and as being pivotally connected with the contact member by means of a transverse pivot pin I2 which extends through openings in the side plates 51, 5a of the contact member. Shoulders of bushings serve to hold the actuator il in its normal central position. A coil spring it surrounds one of the shoulders or bushings on the pin I2, and this spring engages the actuator and one of the side plates and serves to bias the actuator for movement in the clockwise direction. As hereinafter explained in detail the actuator II is normally held against movement with respect to the contact member.

A suitable operating means is provided, this means preferably comprising two links or members I4 and I5 pivotally connected with each other at I6. The link or member I4 is formed to also constitute a handle and it is pivotally mounted on the housing for movement about a transverse axis at Il. A portion I4EL of the handle member I4 projects forward and is exposed so as to be conveniently accessible for manual operation. The link I5 comprises two separate elements |53, I5 space-d apart transversely, and separately connected with plates I8, I8 secured to the member I4.

The two elements I 5B, IEE of the link I5 are pivotally connected at I9 with the actuator ii. With the parts in the position shown in Fig. 8 the two members or links I4 and I5 constitute an overset toggle which holds the contact member in its contact engaging or circuit-closing position. Movement of the links I4 and I5 beyond the position shown in Fig. 3 is prevented by the engagement of the handle portion I4a with a shoulder on the housing.

Movably connected with the contact member 5 is trip member 20, this being mounted upon a transverse pivot pin 2| extending between the sidewalls 5B, 5a of the contact member. The trip member is held in ycentral position by suitable shoulders or bushings on the pin 2|. Normally the trip member is held in fixed relationship with the Contact member and to this end the trip member and the contact member are normally connected by means of an electro-responsive latch which ispreferably carried by the contact member and which releasably engages the trip member.

As concerns the present invention I do not narrowly limit myself as to the exact character of the electro-responsive latch but I prefer and have shown-a latch which consists of a bi-metallic thermally responsive strip 22. This strip carries a transverse latch bar 22HL which normally engages with the trip member 20. The trip member `is preferably normally positioned parallel with the side plates 5, 5n and transversely to the direction of movement of the contact member. The latch 22 is between the side plates and is preferably approximately perpendicular to the trip member, extending approximately in the direction of movement of the contact member.

Preferably, but not necessarily, the latch 22 is electrically connected to form a part of the circuit and to be directly heated by the current. For supporting the latch 22 and for providing electrical connection therewith, the transverse plate 6 is formed with an integral extension 6b which is offset rearward and which extends downward between the side plates 5a, 5H. At its lower end the extension 6b has transverse lugs Iic which extend through holes in the side plates 5e, 5n to assist in holding the extension 6b in place. The bi-metallic latch 22 has an angularly bent portion 22b which is riveted to the extension 6b. This serves not only to mechanically support the latch but also to electrically connect it with the contact 8. The other end of the b-i-metaliic latch 22 is electrically connected with the transverse plate 1 and with the other movable contact 9 by means of a flexible conductor 23. As shown; in Fig. 5 the conductor 23 is doubled to provide increased conducting capacity. Thus with the parts in closed-circuit positions an electrical connection is established from the contacts l and 8 through the conductor 6b, the latch 22 and the conductor 23 to the contacts 9 and 3.

In order that the bi-metallic latch 22 may be readily adjusted there may be provided an arm 24 rigidly secured to the latch near the rear thereof and projecting upward. A screw 25 extends forward through av suitable hole in the conductor 6b and has threaded engagement with a corresponding hole in the arm 24. It will be observed that by turning the screw 25 the latch 22 may be bent or deflected in the clockwise direction in order to change its operating characteristics.

Preferably there is provided a U-shaped insulating plate 26 which extends transversely between the main insulating plates 5, 5a, the main body of the plate 26 being immediately behind the conductor 6b and secured thereto by rivets. rEhe plate 26 has a suitable hole therein to pei'- mit access to the screw 25. The end portions 25H, 2GE of the plate 26 extend forward, being positioned ,respectively below and above the contacts I, Ii and 3, 9. Adjacent these said end portions are other insulating plates 21, 2T, each provided with lugs 21, 2'Ia which project through openings in the main side plates 5a, 51.

The actuator II is suitably connected with the trip member 20 so as to be held in fixed relationship with the contact member so long as the latch 22 holds the trip member in fixed relationship.

The connection is such that, when the latch releases the trip member. the actuator is then free to move relatively to the contact member entirely independently of the trip member. As shown the trip member is provided with a shoulder 2l* which is normally engaged by an extension arm II forming a part oi' the actuator I I. 'I'he trip member is further provided with a rearward extending arm 2IIb which is adapted under certain circumstances, as will be presently explained, to be engaged by the arm I I.

Preferably, to prevent any possible transverse movement of the actuator so as to bring the arm III thereof out of cooperative relationship with the portions 2l) and 20b of the trip member, the link elements I5, I5 are provided with extensions I5", I5 which are positioned at the sides of the arm I IIl to hold it in position.

With the parts in closed-circuit positions, as shown in Fig. 3, the movable contacts are firmly pressed against the rupture contacts, which have been moved rearward to a slight extent from their free positions. 'I'he overset toggle Il, I5 prevents circuit-opening movement as a result of the bias of the springs I0, III. The pressure exerted by said springs III, III and the pressure exerted on the contacts 8 and 9 by the contacts I and 3, are transmitted through the link I5 and the operating member I4 and serve to normally hold the operating member in its closed-circuit position. Inasmuch as the centerline of the link I5 extending through the pivotal axes I6 and I9 is below the actuator axis I2, the force transmitted through the link I5 reacts totend to move the actuator I I in the counter-clockwise direction against the bias of the spring I I thus holding the arm II of the actuator against the shoulder 20l of the trip member.

The toggle operating means Il, I5 can be manually released by moving the operating member Il in the counter-clockwise direction sufficiently to break the toggle. Thereupon the parts move to the open-circuit position as shown in Fig. 7 under the influence of the springs I0, III.

As already stated, the latch 22 is responsive to current in the circuit, being preferably connected electrically to form a part of the circuit. Upon the attainment of excess current conditions in the circuit the bi-metallic latch is heated by reason of the current therein, and it is deflected downward so that the latch bar 22* is disengaged from the trip member 20. It the operating member is manually held in closed-circuit position, as shown in Fig. 8, the trip member will move forward to the position shown in the said figure as soon as released by the latch. This forward movement of the trip member occurs as they result of the pressure exerted by the arm IIB against the shoulder 20". As soon as the trip member has moved sufiiciently to disengage the shoulder 20* from the arm II, the actuator moves in the counterclockwise direction, and at the same time the contact member moves in the forward direction, these movements being caused by the springs I0, I Il which overcome the spring I3. As the result of this movement the parts reach the relative positions shown in Fig. 9, the movable contacts being separated from the stationary contacts and the circuit being broken at two places.

With the contact member in its extreme forward position as shown in Fig. 9, the springs I0, I are no longer effective and the spring Il tends to move the actuator I I in the clockwise direction. However, so long as the handle is held in closedcircuit position such movement of the actuator is prevented by the link I5. with the parts in closed-circuit positions as shown in Fig. 3, the centerline oi' the link I5 extending through the pivotal axes I and Il, is below the pivotal axis II of the operating member. However, when the parts shift to the relative positions shown in Fig. 9 the said centerline of the link I5 is above the pivotal axis at I1. Therefore upon release of the handle or operating member the actuator II is moved in the clockwise direction by the spring I3 and at the same time the link I5 moves the operating member in the counter-clockwise direction to the open-circuit position.

When the actuator nears the end of its movement in the clockwise direction, the arm IIl thereof engages the arm 20h on the trip member, as shown in Fig. 10, and moves the trip member in the counter-clockwise direction to restore it to latching relationship with the latch 22. This brings the shoulder 20l on the trip member into engaging relationship with the arm IIa of the actuator, as shown in Fig. '7, and all of the parts are in the proper relationship for effecting reclosing of the circuit breaker, assuming of course that the latch has cooled sufciently to engage the trip member.

The operation has been described upon the assumption that the handle is first held and then released. It will, of course, be understood that such holding does not ordinarily occur and that the parts move automatically and in succession to the positions shown in Figs. 8, 10 and 7, without assuming the relationship shown in Fig. 9.

From the drawings and from the foregoing description it will be apparent that by providing for movement of the actuator entirely independently of the trip member, I avoid any large or extensive or excessive movement of the trip member, while nevertheless permitting the necessarily extensive movement of the actuator. It will further be apparent that a very large portion of the pressure, stress or force necessary to move and hold the Contact member is transmitted directly from the actuator to the contact member. The relationship of the parts is such that the force transmitted to the shoulder 20a is only a small portion of the total force transmitted through the link I5; and the force transmitted from the trip member to the latch 22 is only a very small portion of the pressure exerted against the-shoulder 20a. By reason of this double reduction the force transmitted to the latch is very small, and it therefore follows that the latch is substantially free to deflect in accordance with temperature conditions Without being unduly hampered or retarded by friction exerted unon it by the trip member.

In the foregoing description I have referred only briefly to the enclosing casing or housing, as this may be widely varied so far as the mechanism of the circuit breaker is concerned. However, in accordance with one phase of the invention I provide a housing which has important advantages, particularly when used with o. circuit breakerof the type which has been described.

The housing which I prefer and which I have shown is 'of insulating material, and the said housing comprises two sections 28, 28 which enclose all of the essential circuit breaker parts and which serve as the sole supporting and guiding means for these parts. While I do not necessarily so limit myself, the two circuit breaker sections are preferably duplicates of each other thus reducing the cost of manufacture and providing other important advantages. These two sections are assembled in relatively reversed positions but their construction is or may be identical in all respects. The housing sections are connected with each other by means of screws at 29, 29 and 30, 30; and they may be mounted on a rear supporting wall by means of screws inserted in the holes 3I, 3|. The housings are narrow and have flat side faces so that a plurality of them may be arranged in closely banked relationship.

Each of the housing sections 28 is provided with a main central recess 32 which is rectangular, the said recesses in the two sections registering with each other to form a chamber which is substantially closed at all sides and which receives and encloses most of the mechanism of the circuit breaker. The recesses 32, 32 are of such length that the ends thereof have direct guiding engagement with the ends of the side plates 5a, 5t1 of the contact member; and the recesses are of such width that the sides thereof have direct guiding engagement with the sides of the said plates 59, 5a. The sidesof the recess preferably have suitable clearance grooves 32a, 32EL and 32b therein as clearly shown in Fig. 2. I'he grooves 32B, 32L provide clearance for the ends of the pivot pin 2| and for the lugs 6a, 'Ia and 21e; and the groove 32b provides clearance for the ends of the pivot pin I2 and for the lugs 3C, ISC. The front walls or" the recesses serve as stops to limit forward movement of the contact member.

The handle member I4 is provided with a pivot pin or trunnion at I1, the ends of the trunnion being seated directly in suitable holes formed in the side walls of the housing sections 28, 28. The housing sections are provided at the front with arcuate notches 33, 33 which register with each other to provide a slot through which the handle portion I4L1 of the operating member I4 projects. As already stated, the housing sections constitute the sole guiding and supporting means for the movable parts of the circuit breaker. By this I mean that the said movable parts are supported and held in proper relationship by reason of their direct engagement with the housing parts, there being no additional or separate frame structure having this function. When the housing sections are separated the movable parts of the circuit breaker are freely separable there- Afrom and when so separated they are no longer held in their normal operative relationship; that is with the movable parts of the circuit breaker removed from the housing, the handle member I4 has no fixed relationship to the Contact member 5 and can be freely moved in any direction within the limits permitted by the connecting link I5.

'I'he springs I0, I0 which have already been referred to are preferably at zigzag springs which are positioned in the shallow grooves 321, 32b already referred to. These springs are provided at their upper ends with hooks Ilia, I which engage annular grooves in the trunnion I1 for the operating member.

In addition to the screws 29, 29 and 30, 3IIA for connecting the housing sections, I preferably provide two metallic transverse connecting elements located respectively near the top and bottom of the housing. These two transverse connecting elements may be formed integrally with vthe before mentioned conductors 2 and 4 and they are so shown, being designated asy 2a and 4a. The transverse member 2Ja is connected with the housing sections by means of screws 34, 34 and the transverse member 4* is connected with the housing sections by means of screws 35, 35. Carried by the transverse connecting elements 2* and 4* are suitable wire connectors or terminals 36 and 31.

Formed in the inner faces of the two housing sections are registering grooves forming at least one arcing vent adjacent each arcing zone. Preferably a plurality of such vents are provided adjacent each arcing zone, these being indicated at 38, 38 and 39, 39. These vents communicate with the exterior of the housing and preferably such communication is eiected through other registering grooves 40 and 4I which form tortuous passageways. By referring particularly to Fig. 9 it will be observed that any gases formed .from arcs resulting from separation of the contacts are entirely enclosed Within the chamber 32 and can escape only through the vents 38, 38 and 39, 39 and through the passageways 40 and 4I. In so escaping the gases are passed over the surface walls of the vents and passagewaysand are thus cooled so that no llame can pass to the exterior. It will also be observed that the insuiating plates 26 and 21, 21 prevent the arc formed gases from passing inward to any considerable extent, thus protecting the latch and the movable parts of the mechanism from the action of such gases.

In order to prevent the gases from escaping through the openings which are necessarily provided for the resilient contact supports 2 and 4, movable insulating shields 42 and 43 are provided. These shields have holes therein through which the supports 2 and 4 extend and which they closely t. The shields are seated in shallow grooves 44 and 45 in the top and bottom walls of the recesses 32. Preferably, as shown in Fig. 5, the grooves 44 and 45 are extended transversely into the side walls of the housing sections and the shields extend into these extensions. Thus the shields are accurately guided for forward and rearward movement in accordance with the forward and rearward movement of the contact supports.

What I claim is:

l. An automatic circuit breaker comprising in combination, a rupture contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable witlrthe rupture contact, an actuator connected with'the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and trip member to maintain them in xed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, and means normally enabling the trip member to hold the actuator in fixed relationship with the Contact member and serving upon release of the trip member to release the actuator and permit it to move independently of the trip member thus enabling the contact i member to move automatically in the circuitopening direction.

2. An automatic circuit breaker comprising in combination, a rupture contact, a movable contact member biased in the circuit-opening direction and includingan electric contact engageable with the rupture contact, an actuator connected with the contactmember for movement bodily therewith and also for movement relative thereto. operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and trip member to maintain them in ilxed relationship, the said latch serving upon the attainment oi' abnormal current conditions in the circuit to release the trip member for independent movement, means normally enabling the trip member to hold the actuator in xed relationship with the contact member and serving upon release of the trip member to release the actuator and permit it to move independently o1' the trip member, and toggle links connected with the actuator to control it and adapted when in overset relationship to normally hold the actuator and contact member in closed-circuit positions, the said links being normally held in their said overset relationship by pressure transmitted from the contact member and being biased for movement to their open-circuit relationship when such pressure is reduced by reason oi.' the relative movement oi the actuator upon being released from the trip member.

3. An automatic circuit breaker comprising in combination, two rupture contacts spaced apart, a movable contact member biased in the circuitopening direction and including two electric contacts engageable with the respective rupture contacts, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, a bodily movable bi-metallic latch electrically connected between the movable contacts and normally mechanically connecting the contact member and the ltrip member to maintain them in ilxed relationship,v the said latch serving upon the attainment of abnormal current conditions therein to automatically deflect so as to release the trip member for independent movement, andv means normally enabling the trip member to hold the actuator in xed relationship with the contact member and serving upon release of the trip member to release the actuator and permit it to move independently of the trip member thus enabling the contact member to move automatically in the circuit-opening direction.

4. An automatic circuit breaker comprising in combination, a rupture contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the rupture contact, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, an electro-responsively controlled latch bodily movable with the contact xnembei` and movable relatively thereto upon the attainment of abnormal current conditions in the circuit, and a trip member movable relatively to the contact member and normally directly engaging the actuator to prevent relative movement thereof, the said trip member being normally engaged and held by the latch and being released upon electro-responsive movement thereof so as to disengage the actuator to permit movement thereof independently of the trip member and to thus enable the contact member to move automatically in the circuit-opening direction.

5. An automatic circuit breaker comprising in combination, a rupture contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the rupture contact, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, an electro-responsively controlled latch bodily movable with the contact member and movable relatively thereto upon the attainment of abnormal current conditions in the circuit, and a trip member movable relatively to the contact member and having a shoulder with which the actuator normally directly engages to prevent relative movement oi' the latter, the said trip member being normally engaged and held by the latch and being released upon electroresponsive movement thereof so as to disengage its said shoulder from the actuator and permit the latter to move independently or the trip member and to thus enable the contact member to move automatically in the circuit-opening direction.

6. An automatic circuit breaker comprising in combination, a rupture contact, a rectilinearly movable contact member biased in the circuitopening direction and including an electric contact engageable with the rupture contact, an actuator connected with the contact member for movement bodily therewith and also for relative pivotal movement about a transverse axis, operating means engaging the actuator to control it, a bi-metallic latch carried by the contact member and extending approximately in the direction of movement thereof, the said latch being adapted toautomatically deflect upon the attainment of abnormal current conditions in the circuit, and a trip member connected with contact member for relative pivotal movement about a transverse axis and having a shoulder with which the actuator normally directly engages to prevent relative movement of the latter, the said trip member being normally approximately perpendicular to the latch and being normally engaged and held thereby and being released upon automatic deilection of the latch so as to disengage its said shoulder from the actuator and permit the latter to move independently of the trip member and to thus enable the contact member to move automatically in the circuit-opening direction.

7. The combination in an automatic circuit breaker, of a rupture contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the rupture contact, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, an electro-responsively controlled latch bodily movable with the contact member and movable relatively thereto upon the attainment of abnormal current conditions in the circuit, a trip member movable relatively to the contact member and normally directly engaging the actuator to prevent relative movement thereof, the said trip member being normally engaged and held by the latch and being released upon electro-responsive movement thereof so as to release the actuator to permit movement thereof independently of the trip member and to thus enable the contact member to move automatically in the circuit-opening direction, and means engageable with the trip member to restore it tov latching relationship with the latch when the rupture contact, an actuator connected with the contact member for movement bodily there-v with and also for movement relative thereto, operating means engaging the actuator to control it, an electro-responsively controlled latch bodily movable with the contact member and movable relatively thereto upon the attainment of abnormal current conditions in the circuit, a trip member movable relatively to the contact member and normally directly engaging the actuator to prevent relative movement thereof, the said trip member being normally engaged and held by the latch and being released upon electroresponsive movement thereof so as to release the actuator to permit movement thereof independently of the trip member and to thus enable theV an electro-responsively controlled latch bodily l movable with the contact member and movable relatively thereto upon the attainment of abnormal current conditions in the circuit, a trip -f member movable relatively to the contact member and having a shoulder with which the actuator normally directly engages to prevent relative movement of the latter, the said trip member being normally engaged and held by the latch and being released upon electro-responsive movement thereof so as to disengage its said shoulder from the actuator and permit the latter to move independently of the trip member and to thus enable the contact member to move automatically in the circuit-opening direction, toggle links connected with the actuator to control it and adapted when in overset relationship to normally hold the actuator and contact member in closedcircuit positions, the said links being normally held in'their said overset relationship by pressure transmitted from the contact member and the said links and actuator being biased for movement to their open-circuit relationship when such pressure is reduced by reason of the relative movement of the actuator upon being released from the trip member, and means engageable with the trip member to restore it to latching relationship with the latch when the links and the actuator and the contact member are moved to their open-circuit positions.

10. kIn an automatic circuit breaker, the combination of two rupture contacts, a rectilinearly movable contact member including two transversely spaced insulating side plates and also including two separate electric contacts carried by the side plates and engageable with the respective rupture contacts, a manually movable operating member, mechanism operatively connecting theoperating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and two tension springs connected with the side plates at the outer sides 'thereof for biasing the contact member in the circuit-opening direction.

1l. In an automatic circuit breaker, thel combination of two rupture contacts, a rectilinearly movable contact. member including two transversely spaced insulating side plates and also including two separate electric contacts carried by the side plates and engageable with the respective rupture contacts, a manually movable 'the operating member upon the attainment of abnormal current conditions in the circuit, and two substantially flat zigzag tension springs closely adjacent the outer surfaces of the side plates and connected with the said plates for biasing the contact member in the circuit-opening direction.

l2. The combination in an automatic circuit breaker, of a rupture contact, a movable contact member provided with a contact engageable with the rupture contact, a manually movable operating member, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and a two-section insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and having the division plane between the two sections parallel with the direction of movement of the contact member, the said housing sections serving as the sole supporting and guiding means for the aforesaid parts and being free from positive connection with any substantially movable parts so that when the sections are assembled the said parts are guided and held between them and so that when the sections are separated the said parts are freely separable therefrom.

13. The combination in an automatic circuit breaker, of a rupture contact, a rectilinearly movable contact member provided with a contact engageable with the rupture contact, a manually movable pivoted operating member, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and a two-section insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and having the division plane between the two sections parallel with the direction of f movement of the contact member, the said housing sections serving as the sole means for rectilinearly guiding the contact member and for pivotally supporting the operating member and the said housing sections being free from positive connection with any substantially movable parts so that when the sections are assembled the said parts are guided and held between them and so that when the sections are separated the said parts are freely separable therefrom.

14. In an automatic circuit breaker, the combination of two rupture contacts spaced apart 75 near the rear, a contact member rectilinearly movable forward and rearward and provided with two contacts engageable with the respective rupture contacts, a manually movable pivoted operating member at the front, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and an insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and comprising two duplicate sections having the division plane between them parallel with the direction of movement of the contact member, the said housing sections serving as the sole supporting and guiding means for the aforesaid parts and being free from positive connection with any substantially movable parts so that when the sections are assembled the said parts are held and guided between them and so that when the sections are separated the said parts are freely separable therefrom.

l5. In an automatic circuit breaker, the combination of two rupture contacts spaced apart near the rear, a contact member rectilinearly movable forward and rearward and provided with two contacts engageable with the respective rupture contacts, a manually movable pivoted operating member at the front, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and an insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and comprising two duplicate sections having the division plane between them parallel with the direction of movement of the contact member, the said housing sections serving as the sole means for rectilinearly guiding the contact member and for pivotally supporting the operating member and the said sections being free from positive connection with any substantially movable parts so that when the sections are assembled the said parts are held and guided between them and so that when the sections are separated the said parts are freely separable therefrom.

16. In an automatic circuit breaker, the combination of two rupture contacts spaced apart near the rear, a contact member rectilinearly movable forward and rearward and comprising two flat insulating plates spaced apart transversely and carrying two contacts engageable with the respective rupture contacts, a manually movable pivoted operating member at the front, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and an insulating housing enclosing all of the aforesaid parts otherv than the manually engageable portion of the operating member and comprising two duplicate sections having the division plane between them parallel with the said plates of the contact member, the'said housing sections serving as the sole means for rectilinearly guiding the contact member and for pivotally supporting the operating member and the said sections being free from positive connection with any substantially movable parts so that when the sections are assembled the said parts are held and guided between near the rear, a contact member rectilinearly movable forward and rearward and provided with two contacts engageable with the respective rupture contacts, a manually movable pivoted operating member at the front, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and an insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and comprising two duplicate sections having the division plane between them parallel with the direction of movement of the contact member, the two housing sections having registering grooves therein adjacent the rupture contacts and constituting arcing vents communicating with the exterior of the housing.

18. In an automatic circuit breaker, the combination of two rupture contacts spaced apart near the rear, a contact member rectilinearly movable forward and rearward and provided with two contacts engageable with the respective rupture contacts, a manually movable pivoted operating member at the front, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, and an insulating housing enclosing al1 of the aforesaid parts other than the manually engageable portion of the operating member and comprising two duplicate sections having the division plane between them parallel with the direction of movement of the contact member, the two housing sections having therein at each end a plurality of registering grooves forming arcing vents adjacent the corresponding contacts and also having at each end other registering grooves communicating with the said vents and forming tortuous passageways communicating with the exterior of the housing.

19. The combination in an automatic circuit breaker, of two rupture contacts spaced apart, near the rear, a rectilinearly movable contact member provided with a contact engageable with the rupture contact, a manually movable operating member, mechanism operatively connecting the operating member with the contact member and including an element adapted te release the contact member from the control of the operating member upon the attainment of abnormal current conditions in the circuit, a two-section 'insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and having the division plane between the two sections parallel with the direction of movement of the contact member, and two metallic elements carrying the respective rupture contacts and each having its end portions connected to the respective housing sections.

20. The combination in an automatic circuit breaker, of two stationary rupture contacts spaced apart near the rear, a rectilineariy movable contact member provided with a contact engageable with the rupture contact, a manually movable operating member, mechanism operatively connecting the operating member with the contact member and including an element adapted to release the contact member from the control o! the operating member upon the attainment of abnormal current conditions in the circuit, a two-section insulating housing enclosing all of the aforesaid parts other than the manually engageable portion of the operating member and having the division plane between the two sections parallel with the direction of movement o! the contact member, the said housing sections serving as the sole means for rectilinearly guiding the contact member and for pivotally supporting the operating member and the said sections being free from positive connection with any movable parts so that when the sections are assembled the said parts are guided and held between them and so that when the sections are separated the said parts are freely separable therefrom, and two metallic elements carrying the respective rupture contacts and each having its end portions connected to the respective housing sections.

PAUL M. CHRIS'IENSEN.

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