US3291938A

US3291938A - Circuit breaker

Info

Publication number: US3291938A
Application number: US433091A
Authority: US
Inventors: Martin V Zubaty
Original assignee: Mechanical Products Inc
Current assignee: AMSTAR TECHNICAL PRODUCTS COMPANY Inc A CORP OF DE; Aiken Industries Inc
Priority date: 1965-02-16
Filing date: 1965-02-16
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13
Also published as: NL6515005A; DE1513371A1; DE1932287U

Description

M. V. ZUBATY CIRCUIT BREAKER Dec. 13, 1966 5 Sheets-Sheet 1 Filed Feb. 16, 1965 De. 13, 1966 M. v. zUBATY 3,29938 CIRCUIT BREAKER Filed Feb. 1e, 1965 .'3 Sheets-Sheet i3 /ff f M. V. ZUBATY CIRCUIT BREAKER Dec. 13, 1966 3 Sheets-Sheet 3 Filed Feb. 16, 1965 2%@ 721/22 l( ELI/Egg?? /9' faWA/E/S'.

United States Patent O Filed Feb. 16, 1965, Ser. No. 433,091 8 Claims. (Cl. 2011-116) 'Ihis invention relates generally to electric circuit breakers and more pa-rticularly to an improved multi-pole, trip free, common trip type of circuit breaker.

Multi-pole, automatic, electric circuit breakers of the type with which the invention is concerned are often used to protect multi-phase branch circuits which are connected at one end thereof to a multi-phase power supply and at the other end to a multi-.phase load, for example, three phase motors and other like multi-phase devices. The circuit breakers generally comprise a plurality of electrically isolated pairs of separable contacts, a releasable operating mechanism for eifecting simultaneous separation of the respective pairs of contacts and a trip device which is responsive to predetermined conditions in any one of the phases of the electrical circuit to effectuate the release of the operating mechanism of the circuit breaker and to open each of the phases of the branch circuit.

Typically, the trip device of such circuit breakers comprises a latch mechanism which is operatively connected to a current responsive member and is operable to effect the engaging and disengaging movement of the latch. In operation, the latch must be relatively strong mechanically in order to retain the operating mechanism in the closed condition and suicient contact pressure must be applied to insure the proper electrical contact of the circuit breaker contacts. In addition, the mechanism must be readily releasable upon relatively slight movement of the latch proper and in response to -a slight variation in the condition of the current responsive member in any one of the plurality of phases. vThe current responsive member must be sensitive to a relatively small increment of change in current above a preselected maximum and have a physical response characteristic which is capable of releasing the latch in the manner described above. In certain prior art multiple circuit breakers for use with a multi-phase branch circuit, the contact pressure of the contacts has been directly related to the number of contacts which are located within the circuit breaker. Thus difficulty has arisen in providing the proper contact pressure for each individual pair of contacts and the current carrying requirement impressed thereon.

' Also in certain other of the prior art circuit `breakers of this type, the latch mechanism has been connected through a llexible member to a contact carrying element wherein the flexible element is required to Hex in accordance with t-he amount of contact pressure which is to be applied. In the type of ilexible member which has been used in they past, it has been found that, through the heat of the unit, the llexible element has been fatigued and often fractures in use, thereby causing the circuit breaker to fail. While t-he breaker may fail safe, it is necessary that the breaker be replaced thereby causing the circuit to be out of use, both for the time that the element is fractured and for the time that is required to replace the breaker. Also certain other problems have arisen in the prior art breakers in the force system set up within the breaker in order to keep the proper contact pressure rice between the contacts and it is with these forces that the invention is directed in addition to the aforementioned areas.

One of the important considerations of multi-phased breakers of this type is to provide a reliable and fast acting breaker wherein each of the phases of the multi-phased circuit is effectively and rapidly broken without the dangerof one of the phases remaining in contact. With certain of the prior art devices, each .phase was independently sensed to provide an independent trip for the corresponding portion of the breaker, It is desirable that a single member sense the conditions of all three phases of the branch circuit conjunctively rather than have individual sensers for the individual circuits and introducing the problem of relating all of the conditions of the circuit to a single latch element. Thus it is desirable that individual units produce a signal condition according to the conditions within the branch circuit and a single member sense the signal condition to activate one member which will in turn disengage all of the plurality of pairs of contacts in each phase of the branch circuit. This action should be relatively fast and reliable for the aforementioned reasons and must Ibe capable of withstanding severe vibra- Ation and transient effects in the environment with which the circuit breaker is involved. Also, the circuit breaker should be capable of withstanding relatively high instantaneous fault current over and above the normally encountered overload current to which the circuit breaker is responsive. Thus a failure in one phase should produce substantially the same trip result in the circuit breaker as a failure in all of the phases of a multi-phase circuit.

In utilizing a multi-pole circuit breaker fabricated according to the principles of the present invention, the user is insured of positive overload protection for relatively loW current multi-phase circuits by utilizing a trip device for the contacts which is sensitive to a low fault in any one of the phases, a large fault in any one of the phases or any combination of the two. The overload current is sensed and a signal condition produced by a heater element which is electrically connected in each of the branch circuits of the multi-phase system. In turn, this signal condition is sensed by a bimetallic element which is connected to a trip lever assembly common to all of the phases of the branch circuit. The latch mechanism has been constructed of a pair of resiliently biased members, one of which carries a movable contact element and the other of which is engageable with the trip lever mechanism, thus providing a ilexible connection between the two elements of the latch mechanism. With certain modifications, the circuit breaker unit of the instant invention is of the general type disclosed in Patent No. 3,145,281,

issued to the common assignee on August 18, 1964, and entitled Multi-Pole Circuit Breaker With Trip Devices Located In the Housing Of a Single Pole.

Accordingly, it is one object of the present invention to provide an improved automatic multi-pole circuit breaker for use in protecting relatively low current multi-phase circuits.

Another object of the present invention is to provide a multi-pole circuit breaker that operates substantially instantaneously upon a relatively small current overload.

Another object of the present invention is to provide an improved circuit breaker having improved overload sensing features.

It is still a further object of the present invention to 3 provide an improved circuit breaker having improved means for applying contact pressure to the pairs of contacts thereof.

It is still another object of the present invention to provide a circuit breaker having improved means for correlating overload conditions in any one of or all of the phases of a multi-phase circuit.

It is still another object of the present invention to provide a circuit breaker having improved force distribution characteristics within the structural elements of the circuit breaker.

It is still a further object of the present invention to provide a circuit breaker having improved latch trip features wherein the response of the circuit breaker is greatly enhanced.

It is still a further object of the present invention to provide a multi-pole circuit breaker which is simple to construct and inexpensive to manufacture.

Further objects, features, and advantages of this invention will become apparent from a consideration of the following description, the appended claims and the accompanying drawing in which:

p FIGURE l is a top, partially broken away view of a multi-pole circuit breaker incorporating certain principles of the present invention and illustrating the heater and trip assemblies thereof;

FIG. 2 is an elevational side view of the multi-pole circuit breaker of FIGURE l taken along line 2-2 thereof and particularly illustrating the trip lever and latching assembly;

FIG. 3 is an elevational view of the circuit breaker assembly of FIG. 2 and taken along the line H3-3 thereof and particularly illustrating the heater assembly; and.

FIG. 4 is another cross-sectional view of the circuit breaker assembly of FIG. 2 taken along line 4-4 thereof.

Referring now to the drawings, there is illustrated a multi-pole, trip free electric circuit breaker 10, constructed in accordance with a preferred embodiment of the present invention and comprises an insulating housing 12 fabricated of ceramic or other like insulating material, portions of which are held together by screws 14, rivets 15 or other like fastener means. The front is closed by means of a metal cover member 13 and a wafer like insulating means 16 suitably insulates the inner portions of the breaker from the cover 13 and suitably seals the juncture between certain portions of the circuit breaker housing 12 and the cover 13. The housing generally comprises a plurality of

interconnected sections

18, 20 and 22, which house the various portions of the circuit breaker associated with each of the phases of the multiphase circuit. The sections are divided by suitable dividing means 24 which may take the form of integrally molded projections depending from the interior of the housing. The projections 24 may also serve to fasten the upper portion of a yoke member 26 which is utilized to separate the three sections illustrated and also to sup port the elements within the circuit breaker assembly as will be hereinafter explained.

The lower portion of the U-shaped frame is rigidly fastened to the cover 13 of the circuit breaker housing 12 by means of rivets 28, and a Washer member 30. The housing 12 may be held together by a suitable means such as rivets or screws passing through the two halves of the housing. The upper portion of the housing 12 is provided with a plurality of pairs of terminals 30-32, 34-36, and 38-40 which are suitably fastened in position relative to the housing, by means of a plurality of pairs-of screws, 42, 44 and 46. A plurality of

insulating barriers

47, 49, 51 and 53 suitably insulate the pairs of conductors of each phase relative to each other and also provide additional rigidity to the structure. With suitable conductors connected to the terminals, such as

terminals

34, 36, the current will pass through the circuit breaker section corresponding thereto, as from terminal 36 and will exit from the breaker, as at terminal 34. Thus a 4 control of the current in each of the branches by means of the circuit breaker will be efectuated. While only the center section of the breaker will be described, it is to be understood that each of the sections is substantially identical in material details and any exception will be specifically noted.

The mounting screws 44 pass through a generally T-

shaped section

48 and 50 of the

terminals

34, 36, respectively, and the lower portion 50 provides a mounting surface for a fixed contact 52, which is adapted to mate with a movable contact 54. The three pairs of terminals -30-32, 34-36 and 38-40 are adapted to be connected to opposite sides of an external 3-phase electrical circuit so that current normally flows from one terminal through the circuit breaker to the associated terminal. With the contacts of any one pole in the tripped or open position due to a current overload condition, an interruption of the current ilow through the circuit breaker 10 will be effected, as is seen in FIG. 2. The movable Contact 54 is mounted on a rotatable latch assembly 58, the details of which will hereinafter be described. The connection through the circuit breaker is made by a pigtail conductor 60, one end of which is connected to the latch assembly 58 and the other end is connected to a heater assembly 62. As was stated above, only the center unit of the circuit breaker will be described for simplicity. However, it is to be noted that many of the assemblies described in conjunction with the description of FIG. 2 have counterparts in the other two portions of the circuit breaker. Where these assemblies have not been given separate reference numerals, they will be given the primed or double-primed reference numeral of the corresponding element in the center portion.

From the heater assembly 62, the current flows upwardly to the lower portion 48 of terminal assembly 34 and thus outwardly to the other conductor of the pair of conductors connected to the one phase illustrated. The control of the latch assembly is effected through a heat sensitive trip lever mechanism 66 which engages a portion of the latch assembly 58 to hold it in position until such time as the current overload condition is sensed and the trip lever assembly releases the latch assembly thereby opening contacts 52, 54. The manual reset operation of the latch assemblly is etfectuated through a manual plunger assembly 70, which is suitably connected thereto. Asbest seen in FIG. 2, the manual plunger assembly 70 extends externally of and is slidably supported in a threaded nipple 72 which is integrally formed with the metal cover member 13 mounted on the lower portion of the housing 12.

The plunger assembly 70 includes `a compression spring', 76 which 4is adapted to albut at one end thereof against a. shoulder 78 former integrally with a sleeve member 80A and the other end of -tfhe .spring is adapted t'o abut inwardly extending shoulder portion 82 formed on the lower por-- tion lo'f the housing member 12. In this way the plunger ass'emlbly is held in the outwardly lbiased position. The; plunger assembly 4f-urther includes `a manually actuable plunger member 84 which may be integrally fonmed withl the sleeve or formed separately, as illustrated in FIG.. 2. The plunger 4member 84 is connected to an outer' plunger .shaft 88 by means of a pin '90 passing through lboth the plunger member 84 and the outer shaft member 88. It is to be noted that the switch illustrated in FIG. 2 is in the reset position, that is, wherein the contacts 52, 54 are closed and the trip lever bar assembly 66 is in engagement with the latch assembly 58 to resiliently bias contacts 52, 54 together.

The plunger 'operator assembly 70 fur-ther comprises an `inne-r plunger, shaft 92 which is connected to the outer plunger shaft 88 by means of a lost motion connecti-on 94 which generally comprises 4a rivet 94 carried Iin an elongated slot 96, whereby the connection is made between -inner plunger shaft memlber 92 and the outer plunger shaft member 88. The inward and outward movement of the plunger assembly 701 is guided both by the sliding engagement of the sleeve 80 within the nipple 72 and also by means of a pin 98 which lis rigidly fixed in the nipple assembly 72 and slidably engages an elongated slot y100 #formed in the outer plunger shaft member 88.

The outer plunger :shaft 88 is held in its retracted position by a toggle lever assembly 104 having a biasing arm 106 which tends to bias a toggle lever 108 in a direction toward the outer plunger shaft 88. The toggle lever 108 is pivotally mounted on a frame member .110 by means of a pivot pin 112 and the connection between lever arm 106 and toggle lever 108 is made by pin 114. The toggle lever member has a roller member `118 formed at one end thereof which is adapted to engage a cutout portion 120 formed in outer plunger shaft 88. With the roller member 118 engaging slot 120, the plunger assembly is maintained in the retracted position against the bias of the compressed spring 76. The connection between lever arm 106 and toggle lever 108 is made rigid through a cutout portion `formed in one end of the lever arm 106 which engages pin 112, thus forming -a pivotal connection for the toggle lever assembly 104 about pin 112. The biasing 'force which is utilized t-o maintain engagement between roller `11-8 and cutout 120 is provided by spring member 122, as will be seen as t-he description proceeds. It is to be understood that the circuit breaker assembly contains only -a single plunger assembly 70 and toggle lever assembly `104, thereby maintaining the circuit breaker in the set condition with a minimum of parts and allowing the resetting of the tripped mechanism with the motion of a single plunger, `as for example plunger 84. Moreover, a sin-gle trip lever mechanism 66 is provided with separate sensors for each phase for the trip action.

The latch assembly 58 which supports the mov-able contact 54, comprises 1a generally L-shaped contact support element 126 having the contact 54 .soldered or welded to an upper surface of one leg thereof. 'The other leg is provided with a flexible conductor element 128 soldered or welded thereto to conduct t-he current to another portion of the circuit breaker assembly, as will be hereinafter explained. The one leg 127 is connectedto a pivotal pin element 132 which is supported in the .frame 26 by means of a hinge member 134 pivotally mounted on pin 132. Thus, as the L-shaped member 126 and hinge member `134 pivot on pin 132, the contact element 54 will be moved toward and away `from the hxed contact member 52 in an arcuate movement. It is t-o be understood that, while only one latch assembly 58 is illustrated in FIG. 2, there is a corresponding latch assembly 57 and 59 for each phase of the multi-phase circuit, respectively. This may best be seen from the view illustrated in FIGS. 1 and 4 wherein is illustrated the fact that a hinge member corresponding to hinge `member 134 is provided for each of the poles of the breaker .10.

The L-shaped'contact carrying member 126 is r-esiliently biased into the closed position by means of a compression spring 140, which is carried in an open, `generally upwardly extending tubular member 141 mounted on a contact biasing rod member 142 pivotally mounted on pin 132 by means of a generally U-shaped extension member `144 connected thereto at the ends thereof and a pair of hinge extensions 145 integrally `formed with rod member 142 (see FIGURE l). One end 146 of extension member 144 has provided thereon a shoulder member 148 which is adapted to engage a portion of the trip lever assembly 66, thereby main-taining a biasing force on spring element 140. Thus, with the trip lever bar assembly 66 engaging the upper surface of the shoulder member 148, the. other end of the latch assembly 58 will be urged upwardly with the spr-ing 140 into biasing engagement with the upper leg 127. In this way the contacts 52 and 54 will be held in intimate relationship with each other. As in the situation of the hinge member 134the rod member 142 :is common to a plural- 6. ity of tubular members, one for each pole, and each having a spring member carried therein.

As the shoulder element `148 is released by trip lever assembly 66, the spring 140 tends to release the pressure on leg 127 thereby relieving the biasing pressure on the contact element 54. As was s-tated above, spring element 122 resiliently urges roller member 118` into cutout portion and the other end of spring member 122 is fastened to an extension of the rod member 142 thereby tend-ing'to urge the rod member 142 downwardly to provide a resilient biasing force on the shoulder portion 148 upwardly against trip lever assembly 66. -Upon the release of the latch assembly 58 by the trip lever assembly 66, the yforce of spring 122 is relieved .from toggle lever assembly thereby allowing the wheel member 1,18 to disengage `from the cutout portion 120. With the wheel member 1118 disengaged, the plunger assembly 70 will move outwardly of the housing 12 by means of spring 7.6, thereby urging the inner plunger shaft 88 downwardly along with latch assembly 58 and contact element 54. Thus the movable contact element 54 is separated from the fixed contact element 52. As the bias member 142 moves downwardly on being released, a lower face 147 thereof engages a tip 149 `formed on the lower leg of L- shaped member 126 thereby limiting the relatively movement between

members

126 and 142. In this manner the spring is effectively oonned therebetween and the further downward movement of the latch assembly 58 is caused by a pair of spring members 176', 17 6 lconnected to an extension of rod member 142 at one end and trip lever assembly 66 at the other. The complete rotation of the assembly 58 is prohibited by the engagement of a portion of rod member 142 with the support member 26.

The action of the latch assembly 58 is control-led by means of the trip lever assembly 66, which is thermally responsive to the heat generated by current flowing through -a heater assembly 150. The heater assembly generally comprises a

heater unit

151, 152, 153 for each of the phases to be controlled, as best seen in FIG. 3, and has a pair of

outside legs

154, 156 and a middle leg 158 which is connected to the other end of the exible conductor 60. It is to be noted that the exible conductor 60 is covered with a flexible nylon, or other type of insulating material, sleeve in order to prevent -a short circuit with any of the components of the circuit breaker. Thus, in FIG. 2, current enters from terminal 36 and flows tlirough closed contacts 52, 54 through flexible conductor 60 to the

central legs

158, 159 of the heater 150 and out through the

outer legs

154, 156 to terminal 34 by means of terminal member 48. A suitable spring member 160 has been fastened to the heater assembly 150 as a part of assembly 62 and engages a portion of the frame 26 tto provide the necessary spring bias between trip lever assembly 66 and heater assembly 150.

As the heat is generated in heater assembly 150, a bimetallic element 162 of trip lever assembly 66, having a fixed end 164 and a freely movable end 166, is placed in close heat transfer relation with heater 150. As the heat is transferred from the heate-r 150 to the bimetallic elemen-t 162, the freely movable end 166 tends to move away from the p-lunger assembly 70, thereby moving a trip lever bar 170, fastened thereto, away from shoulder member 148. The bimetallic element 162 is fastened to the tri-p lever bar 170 at a central portion thereof by means of a rivet 172. An inward bias for the trip lever assembly is provided by means of a pair of springs 176', 176 which are connected at one end thereof to a pivot pin 178 and at the other end thereof to the extension of the rod member 142, as described above. The pivot pin 178 is rigidly fasten-ed to the trip lever bar by means of a bracket 180 which has been suitably attached the-reto as by rivet 172 and a second rivet 182.

The engagementl between the trip lever bar 170 and the shoulder portion 148 is provided` by means of a shoulder face element 186 which is attached to the trip lever bar by means of .a rivet 188. The lmember 186 has been provided with a downwardly -facing surface 190, which is adapted to engage the upper surface of shoulder member 148, .as is seen from FIG. 2. As bimetallic element 162 extends to the right due to the heating provided through heater 150, the surface 190 will be drawn away from above the shoulder element 148, thereby releasing the latch assembly 58 and the action of disengagement las described above, will occur. The heater assembly 150 is attached to the terminal member 48 at the top of the heater assembly by any suitable -means such as soldering or welding, and a Calibrating screw 194 has been provided in the wall of Ihousing mem-ber 12 to inwardly urge the lower portion of heater 150 toward the bimetallic element 162 -against the action of spring 160. Thus, a control of the amount of heat required to activate bimetallic element 162 has been provided.

As stated above, the invention relates to a multi-pole circuit breaker wherein a plurality of phases .are controlled by means of a pair of contacts `52, 54. Thus it is necessary that three pairs of contacts 52-54, 194-196 and 198-200 are provided to provide the necessary control for the three phases of a ibranch circuit, in the case of a 3- phase system. Also, a plurality of

heater assemblies

150, 152 and 153 are provided to provide heat to a plurality of bimetallic elements 162, 162 and 162" for each of the three heaters, 150, 152 and 153 of each leg of t-he 3- phase system. However, it is to be noted that only one shoulder element 148 has been provided and correspondingly only one face member 186 has been provided inasmuch as a single activation of the trip bar assembly 66 is needed to disconnect -all of the contacts of the system. Thus, a portion of latch assembly 58 will be provided continuously for all three of the poles of the unit and a plurality of springs 140 will be provided, one for each pair of contact elements of the assembly. Thus, as current in any one leg of the branch circuit heats its corresponding heater unit, as for example, heater element 150 to activate bimetallic element 162, the trip lever assembly will be activated thereby unlatching the latch assembly 58.

While it wil-l be apparent that the embodiment of the invention herein disclosed is well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modiication, variation and change without -departing from the proper scope or fair meaning of the sub-joined claims.

What is claimed is:

1. An electric circuit breaker comprising a housing, a stationary contact within said housing, a movable conrtact engageable with saidl stationary contact, a releasable plunger assembly for eiecting movement of the movable contact into engagement with said stationary contact, a trip device having a set conditi-on for maintaining said contacts in engagement and a tripped condition for releasing :the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said movable contact and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a -portion of said motion and relieving said movable contact from said enga-gement when said preselected conditions are sensed including support means supporting said movable contact in pivotal relation to said plunger assembly and biasing means including resilient means resiliently engageable with said support means for urging said movable contact into engagement with said stationary contact, said biasing means including pivot arm means pivotally connected to said operating mechanism and having one end releasably in engagement with said trip device and a portion of the other end thereof including means for lixedly supporting said resilient means on said pivot arm means.

2. An electric circuit breaker comprising a housing, a stationary -contact within said housing, a movable contact engageable with said stationary contact, a releasable plunger assembly for eiecting movement of the movable contact into engagement with said stationary contact, a trip device having a set condition for maintaining said contacts in engagement anda tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger .assembly for relating the motion of said assembly mechanism to said movable contact and engageable with said trip device for urging the engagement of said movable and stationary contacts during at leasta portion of said motion and relieving said movable contacts from sai-d engagement when said preselected conditions are sensed including support means pivotally connected to said assembly for supporting said movable contact in pivotal .relation to said plunger assembly, biasing means resiliently-'engageable with said support means for urging said movable contact into engagement with said stationary contact, said biasing means including an arm pivotally connected t-o said operating mechanism at a central portion and having one end releasably in engagement with said -trip device, a compression spring, and means formed -at the other end of said arm for supporting said spring in resilient lreleasable engagement with said support means.

3. An electric circuit breaker comprising a housing, -a stationary contact within said housing, a movable contact engageable with said stationary contact, a releasable plunger assembly for effecting movement of the movable contact into engagement with said stationary contact, a trip device having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said movable contacts and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are sensed including a generally L- shaped support means pivotally connected to said assembly .at the end of one leg thereof and supporting said movable contact on an upper surface thereof in pivotal relation to said plunger assembly, biasing means resiliently engageable with said support means for urging said movable contact into engagementvwith said stationary contact, said biasing means including an arm pivotally connected at a central portion thereof to said operating mechanism and having one end releasably in engagement with said trip device, a compression spring and cup means formed at the other end of said arm :Eorsupporting said spring in resilient engagement with said support means, said cup means having a portion thereof adapted to engage a portion of said L-shaped support `means in said tripped condition for maintaining said spring in said cup means and engaging said L-shaped member.

4. vAn electric circuit breaker comprising a housing, a stationary Contact within said housing, a movable contact engageable with said stationary contact, a releasable plunger assembly for eiecting movement of the movable contact into engagement with said stationary contact, a trip device having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said movable contacts and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are, sensed including a generally L- shaped support means pivotally connected to said assembly at the end of one leg thereof and supporting said movable contact on .an upper surface thereof in pivotal relation to said plunger assembly, biasing means resiliently engageable with said support means for urging said movable contact into engagement with said stationary contact, said biasing means including an arm pivotally connected at a central portion thereof to said operating mechanism and having one end releasably in engagement with said trip device, a compression spring and cup means formed at the'other end of said arm for supporting said spring in resilient engagement with said one leg of said support means, said L-shaped member having a shoulder portion formed `at the end of the other leg thereof, said shoulder portion being adapted to engage a lower surface of said cup means in said tripped condition for limiting the pivotal movement of said cup means with respect to said support means and maintaining said spring in engagement with said one leg.

5. A multipole electric circuit breaker comprising a housing, a plurality of electrically isolated poles within said housing, a plurality of stationary contacts Within said poles, respectively, a plurality of movable contacts engageable with each respective stationary contact, a single releasable plunger assembly for effecting movement of the movable contacts into engagement with said stationary contacts, a trip device, having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to ya preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said movable contacts and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are sensed including support means supporting said movable contacts in pivotal relation to said plunger assembly and biasing means including resilient means resiliently engageable with said support means for urging said movable contacts into engagement with said stationary contacts, respectively, said biasing means including pivot arm means pivotally connected to said operating mechanism and having one end releasably in engagement with said trip device and a portion of the other end thereof including means for xedly supporting said resilient means on said pivot arm means.

6. A multipole electric circuit breaker comprising a housing, a plurality of electrically isolated poles within said housing, a plurality of stationary contacts within said poles, respectively, a plurality of movable contacts engageable with each respective stationary contact, a single releasable plunger assembly for effecting movement of the movable contacts into engagement with s-aid stationary contacts, a trip device having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said 4movable contacts and engageable with said trip `device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are sensed including support means pivotally connected to said assembly for supporting said movable contacts in pivotal relation to said plunger assembly, biasing means resiliently engageable with said support means for urging said movable contacts into engagement with said stationary contacts, respectively, said biasing means includl0 ing an arm pivotally connected to said operating mechanism at a central portion and having one end releasably in engagement with :said trip device, a compression spring, and means formed at the other end of said arm for supporting said spring in resilient releasable engagement with said support means.

7. A multipole electric circuit breaker comprising a housing, a plurality of electrically isolated poles within said housing, a plurality of stationary contacts within said poles, respectively, a plurality of movable contacts engageable with each respective stationary contact, a single releasable plunger assembly for effecting movement of the movable contacts into engagement with said stationary contacts, a trip device having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said `assembly mechanism to said movable contacts and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are sensed including a generally L-shaped support means piv-otallyconnected to said assembly at the end of one leg thereof and supporting said movable contacts on an upper surface thereof in pivotal relation to said plunger assembly, biasing means resiliently engageable with said support means for urging -said movable contacts into engagement with said stationary contacts, respectively, said biasing means including an arm pivotally connected at ya central portion thereof to said operating mechanism and having one end releasably in engagement with said trip device, a compression spring and cup means formed at the other end of said arm for supporting said spring in resilient engagement with said support means, said cup means having 'a portion thereof adapted to engage a portion of said L-shaped support means in said tripped condition for maintaining said spring in said cup means and engaging said L-shaped member.

8. A multipole electric circuit breaker comprising a housing, a plurality of electrically isolated poles within said housing, a plurality of stationary contacts within said poles, respectively, ya plurality of movable contacts engageable with each respective stationary contact, a single releasable plunger assembly for effecting movement of the movable contacts into engagement with said stationary contacts, a trip device having a set condition for maintaining said contacts in engagement and a tripped condition for releasing the engagement between the stationary and movable contacts in said tripped condition in response to a preselected condition in said breaker, and means operably connected to said plunger assembly for relating the motion of said assembly mechanism to said movable contacts and engageable with said trip device for urging the engagement of said movable and stationary contacts during at least a portion of said motion and relieving said movable contacts from said engagement when said preselected conditions are sensed including a generally L-shaped support means pivotally connected to said lassembly at the end of one leg thereof and supporting said movable contacts on an upper surface thereof in pivotal relation to said plunger assembly, biasing means resiliently engageable with said support means for urging said movable contacts into engagement with said stationary contacts, respectively, said biasing means including an arm pivotally connected at a central portion thereof to said operating mechanism and having one end releasably in engagement with said trip device, a compression spring and cup means formed at the other end of said arm for supporting said spring in resilient engagement with said one leg of said support means, said -shaped member having a shoulder portion formed at 11- the end of the otherleg thereof, said shoulder portion being adapted to engage a lower surface of said cup means in said tripped condition for limiting the pivotal movement of said cup means with respect to said support means and maintaining said spring in engagement with 5 said one leg.

. References Cited by the Examiner LUNITED STATES PATENTS 2,612,296 2,686,241 8/1954 Straub et al. 20o- 116 12 Krieger `200-116 Mascioli et al. 200-116 Ingwersen et al. 200-116 Brackett 200-116 Wood 200-116 Brackett 200-116 Ingwersen 2001-116 Brandenburg 200-124 BERNARD A. GILHEANY, Primary Examiner.

Claims

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING A HOUSING, A STATIONARY CONTACT WITHIN SAID HOUSING, A MOVABLE CONTACT ENGAGEABLE WITH SAID STATIONARY CONTACT, A RELEASABLE PLUNGER ASSEMBLY FOR EFFECTING MOVEMENT OF THE MOVABLE CONTACT INTO ENGAGEMENT WITH SAID STATIONARY CONTACT, A TRIP DEVICE HAVING A SET CONDITION FOR MAINTAINING SAID CONTACTS IN ENGAGEMENT AND A TRIPPED CONDITION FOR RELEASING THE ENGAGEMENT BETWEEN THE STATIONARY AND MOVABLE CONTACTS IN SAID TRIPPED CONDITION IN RESPONSE TO A PRESELECTED CONDITION IN SAID BREAKER, AND MEANS OPERABLY CONNECTED TO SAID PLUNGER ASSEMBLY FOR RELATING THE MOTION OF SAID ASSEMBLY MECHANISM TO SAID MOVABLE CONTACT AND ENGAGEABLE WITH SAID TRIP DEVICE FOR URGING THE ENGAGEMENT OF SAID MOVABLE AND STATIONARY CONTACTS DURING AT LEAST A PORTION OF SAID MOTION AND RELIEVING SAID MOVABLE CONTACT FROM SAID ENGAGEMENT WHEN SAID PRESELECTED CONDITIONS ARE SENSED INCLUDING SUPPORT MEANS SUPPORTING SAID MOVABLE CONTACT IN PIVOT RELATION TO SAID PLUNGER ASSEMBLY AND BIASING MEANS INCLUDING RESILIENT MEANS RESILIENTLY ENGAGEABLE WITH SAID SUPPORT MEANS FOR URGING SAID MOVABLE CONTACT INTO ENGAGEMENT WITH SAID STATIONARY CONTACT, SAID BIASING MEANS INCLUDING PIVOT ARM MEANS PIVOTALLY CONNECTED TO SAID OPERATING MECHANISM AND HAVING ONE END RELEASABLY IN ENGAGEMENT WITH SAID TRIP DEVICE AND A PORTION OF THE OTHER END THEREOF INCLUDING MEANS FOR FIXEDLY SUPPORTING SAID RESILIENT MEANS ON SAID PIVOT ARM MEANS.