US3588761A - Electric circuit interrupter with magnetic trip level adjusting means - Google Patents

Abstract

AN ELECTRICAL CIRCUIT INTERRUPTER HAS A MOVABLE CONTACT CARRIED BY A CONTACT OPERATING MEMBER FOR MOVEMENT RELATIVE TO STATIONARY CONTACTS BETWEEN CLOSED AND OPEN CIRCUIT POSITIONS. OPERATING MEANS WILL MOVE THE OPERATING MEMBER FROM CLOSED TO OPEN CIRCUIT POSITION UPON RELEASE OF LATCHING MEANS ENGAGED THEREWITH. THE CONTACT OPERATING MEMBER CARRIES AN ARMATURE WHICH IS SUBJECT TO THE MAGNETIC ATTRACTION OF A SOLENOID COIL SO AS TO BE MOVABLE TO OPEN CIRCUIT POSITION UPON PASSAGE OF A SHORT CIRCUIT CURRENT OF PREDETERMINED MAGNITUDE THERETHROUGH. A SECOND ARMATURE ALSO ACTED UPON BY THE MAGNETIC FIELD OF THE SOLENOID COIL IS MOVABLE INTO A CIRCUIT OPENING POSITION UPON PASSAGE THROUGH THE SOLENOID COIL OF A LESSER SHORT CIRCUIT CURRENT AND ACTS UPON THE LATCHING MEANS DURING SUCH MOVEMENT TO RELEASE THE OPERATING MEANS FOR AUTOMATIC OPERATION THEREOF. THE BIASING FORCE ACTING UPON THE SECOND ARMATURE AND WHICH MUST BE OVERCOME BY THE SOLENOID FORCE FOR TRIPPING MAY BE PRECISELY ADJUSTED AND THE AIR GAP BETWEEN THE SECOND ARMATURE AND SOLENOID COIL MAY ALSO BE ADJUSTED WITHOUT VARYING THE BIASING FORCE BY MEANS OF A PAIR OF PIVOTABLY INTERCONNECTED ADJUSTMENT LEVERS WHICH ARE PIVOTABLE AS AN ASSEMBLY TO VARY THE AIR GAP.

Description

United States Patent 72] Inventors Eldon B. Heft W. Hartford; Keith W. Klein. Simsbury. both ofConn. [211 App]. No. 14,305 [22] Filed Feb. 26, 1970 [45] Patented June 28, 1971 [73] Assignee General Electric Company [54] ELECTRIC CIRCUIT INTERRUPTER WITH MAGNETIC TRIP LEVEL ADJUSTING MEANS 20 Claims, 6 Drawing Figs. e I [52] U.S. Cl 335/16 I [51] lnt.Cl .-.H0lh77/l0 50 Field olSearch .1 335/16, 265, 259 174 [56] References Cited UNITED STATES PATENTS 1,404,910 1/1922 Thompson 335/259 2,686,278 8/1954 Baston 335/265 3,488,609 1/1970 Stokes Primary Examiner-Harold Broome Attorneys-Robert S. Smith and Robert T. Casey ABSTRACT: An electrical circuit interrupter has a movable contact carried by a contact operating member for movement relative to stationary contacts between closed and open circuit positions. Operating means will move the operating member from closed to open circuit position upon release of latching means engaged therewith. The contact operating member carries an armature which is subject to the magnetic attraction of nitude therethrough. A second armature also acted upon by the magnetic field of the solenoid coil is movable into a circuit opening position upon passage through the solenoid coil of a lesser short circuit current and acts upon the latching means during such movement to release the operating means for automatic operation thereof. The biasing force acting upon the second armature and which must be overcome by the solenoid force for tripping may be precisely adjusted and the air gap between the second armature and solenoid coil may also be adjusted without varying the biasing force by means of apair of pivotably interconnected adjustment levers which are pivotable as an assembly to vary the air gap.

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1 W WWW EM N V B 4 G F 4 TTOR/V' V ELECTRIC CIRCUIT INTERRUPTER WITH MAGNETIC TRIP LEVEL ADJUSTING MEANS BACKGROUND OF THE INVENTION Increasing use of electrical power has produced requirements for power supply systems of ever increasing capacity and a concurrent requirement for circuit breakers capable of interrupting the high circuit currents which can occur in such power systems. Because of the tendency for arcing in such circuit breakers, there has been continuing activity to develop mechanisms for suppression of the arcing and for increasing the rapidity with which the contacts may be opened. Moreover, there has been constant effort to develop means for calibrating with a high degree of accuracy the short circuit current which will produce tripping action.

Since most electrical circuit interrupters employ some form of automatic and manual operating mechanism for moving the contacts between closed and open circuit positions, it is highly desirable thatrapid operation of the contact carrying members be effected independently of the bulk of the operating mechanism upon the occurrence of a high short circuit current. In this manner, the inertia of the relatively massive elements of the operating mechanism will not detract from rapid opening.

A number of arrangements for effecting a disengageable coupling or overrideablc coupling between a contact operating rod and an operating mechanism have been disclosed. One type of mechanism which has proven advantageous in multipole breakers is that shown in Johnson et al. U.S. Pat. No. 3,384,845 granted May 2i, i968 and assigned to the assignee of the present invention. A disengageable coupling between the operating mechanism and the contact operating rod is also disclosed and claimed in Giger U.S. Pat. No. 3,495,l98 issued Feb. 10, 1970 and Hurtle U.S. Pat. No. 3,483,490 issued Dec.

9, 1969, both assigned to the assignee of the present invention.

In the event of rapid opening movement of the contact operating rod independently of the manual operating mechanism, it is still desirable to effect operation of that mechanism in order to permit resetting and to indicate the tripped condition. Moreover, in multipole breakers, it is particularly desirable to effect opening of the contacts in the other pole chambers once tripping has occurred in one of the pole chambers.

In the copending application of Eldon B. Heft, Ser. No. l4,453 filed Feb. 26, i970 entitled CIRCUIT BREAKER WITH LOW SHORT CIRCUIT MAGNETIC TRIPPING MEANS, assigned to the same assignee as the present invention, there is disclosed a novel circuit interrupter construction utilizing a pair of armatures acted upon by the magnetic force generated by passage of a short circuit current passing through a solenoid coil. When the current is of a high magnitude, the primary armature will be rapidly drawn toward the solenoid coil to open the contacts; concurrently, the second armature will be drawn thereto and effect tripping of the operating mechanism and cause opening of the contacts in the other poles in a multipole breaker. When the short circuit current is of a lesser magnitude, the secondary armature alone will initially be drawn to the solenoid coil to effect tripping of the operating mechanism.

Although the mechanism of the aforementioned application permits a desirable adjustment of the trip level short circuit current, even greater precision in control is desirable. This is particularly true with respect to the air gap between the secondary armature and the solenoid coil, and desirably this adjustment should be accomplished without varying the spring force so as to facilitate field utilization.

It is an object of the present invention to provide a novel electric circuit interrupter using solenoid action for opening the contacts therein, wherein the magnitude of the short circuit current in the solenoid for opening of the contacts may be relatively accurately predetermined.

it is also an object to provide such an electric circuit interrupter wherein the ulrgup between the trip armature and the solenoid may be varied without varying the spring tension force required to be overcome by the solenoid.

Another object is to provide such electric circuit interrupter which may be simply and economically constructed and wherein the magnitude of the short circuit current required for opening of the contact may be precisely determined and wherein the mechanism permits movement between high and low settings while maintaining substantially constant spring force.

A further object is to provide such an electric circuit interrupter which may be readily assembled and disassembled and which is capable of long lived operation while affording facile adjustment between high and low settings so as to avoid spurious tripping in surge current applications.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained in an electric circuit interrupter having a casing, at least one stationary contact in the casing, and a movable contact. A contact operating member carries the movable contact adjacent one end thereof and is mounted upon means for movement into and from electrical contact with the stationary contact between closed and open circuit positions. Adjacent the other end of the contact operating member is a first armature which cooperates with a solenoid having one end adjacent thereto. The solenoid generates a magnetic force acting upon the first annature and sufficient to draw the contact operating member into open circuit position upon passage of a short circuit current of the predetermined magnitude therethrough.

A second armature is disposed in the casing adjacent the other end of the solenoid and is attractable thereby, and means in the casing mounts the second armature for movement from a normal position away from the solenoid and towards said solenoid into a circuit opening position upon passage through the solenoid of a short circuit current of predetermined magnitude. A first lever means has one end pivotably mounted in the casing and has its free end extending towards the second armature. Second lever means is pivotably mounted on the first lever means adjacent the pivoted end thereof and it has its free end spaced from the side of the first lever means opposite that adjacent the second armature.

A tension spring means biases the second armature towards the free end of the second lever means, and movement towards the second lever means under such biasing pressure is limited. First adjustment means is provided for varying spacing between the free ends of the first and second lever means and thereby the biasing pressure of the tension spring means, and second adjustment means pivots the first lever means and thereby varies the spacing between the second armature and the solenoid, the spacing between the free ends of the first and second lever means remaining essentially constant during the pivotal movement effected by the second adjustment means.

In the preferred embodiment, the first lever means has its free end bearing against the end of the second armature spaced from the solenoid to limit the movement of the second armature towards the second lever under the action of the tension spring means, and the tension spring means is connected between the second armature and the second lever means. The first adjustment means is desirably a threaded member threadably engaged in one of the lever means and abutting against the other of the lever means. In this embodiment, there is desirably included means in the casing operable against the second lever means to bias the assembly of the first and second lever means towards the solenoid.

The second adjustment means will most usually include a rotatable cam member bearing against the first lever means to produce the pivotal movement thereof upon rotation, and this cam member desirably comprises a cam mounted upon a pivot rotatably supported in and extending outwardly of the casing to permit rotation of the cam.

To effect automatic operation of the circuit interrupter, there is included operating means connected to the contact operating member for automatically moving said member from closed to open circuit position and releasable means latching the operating means against automatic movement. In this embodiment, the second armature acts upon the latching means during movement thereof to the circuit opening position in order to release the operating means for automatic operation thereof. Most usually the second armature has a trip member thereon which is engageable with the latching means to release the operating means. Releasable connecting means are included between the operating means and the contact operating member so that the connecting means is released upon operation of the first armature by the solenoid to permit movement of the contact operating member to open circuit position independently of the operating means.

The operating means includes a pivotable cradle, a toggle mechanism biasing the cradle for pivotal movement upon release of the latching means and releasing means connecting the toggle mechanism to the contact operating member for movement thereof into open circuit position upon pivoting of the cradle. The mounting means for the second armature generally will comprise a guide member in the casing in which the second armature is slidably seated.

When the present invention is employed in a multipole breaker, each of the several pole chambers has the mechanism hereinbefore described except that the operating means and releasable latching means therefor need be incorporated in only one of the pole chambers. In the pole chambers which do not contain the operating means, there is means operable upon the releasable latching means of the pole chamber having the operating mechanism, so that movement of the second armature therein will effect release of the latching means; this may comprise trip members engageable with a common trip pivot shaft upon which the latch means is pivotably mounted so that movement of the armature in any of the pole chambers will effect pivoting of the latching means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a three-pole electrical circuit breaker embodying the present invention with a portion of the casing broken away to reveal internal construction in the center pole and with certain of the elements of the outer pole illustrated in phantom line, the manual operating handle being shown in full line in the on" or closed circuit position and in phantom line in the "off" or open circuit position;

FIG. 2 is a fragmentary side elevational view to an enlarged scale of a portion of the mechanism of the center pole of the circuit breaker of FIG. I with the parts shown in full line in the closed circuit or on" position and with certain of the parts shown in phantom line to represent their position during circuit opening action;

FIG. 3 is a perspective view to a reduced scale of the threepole breaker assembly of FIG. 1;

FIG. 4 is a partially exploded perspective view of the subassembly of the secondary armature and magnetic trip level adjusting means;

FIG. 5 is a fragmentary side elevational view in partial section of the magnetic trip portion of the breaker showing the trip mechanism with the adjusting means in the high setting, the effect of the movement of the spring force adjusting screw producing the variation in length of spring shown in phantom line; and

FIG. 6 is a similar view showing the adjustment for the low setting with the airgap being adjusted from the position shown in FIG. 5 by movement of the cam member.

DETAILED DESCRIPTION OF TH E ILLUSTRATED EMBODIMENT Turning now in detail to the attached drawings, illustrated in FIGS. 1 and 3 is a three-pole breaker assembly embodying the present invention and comprised of three circuit breaker pole assemblies (simply referred to as poles) generally designated by the numerals 2, 4 and 6 disposed within a molded common housing or casing generally designated by the numeral I0. The center circuit breaker pole 4 is illustrated in detail in the remaining FIGS. and includes a portion of the insulating casing 10 which has mounted therewithin a pair of stationary contact assemblies 12, I4, one of which is connected to the line terminal 16 by conductor elements (not shown). The other of the contact assemblies I2, I4 is connected to the load terminal 30 through the solenoid coil 32 by conductor elements (not shown).

Mounted for reciprocal movement within the casing 10 is an elongated contact operating rod I8 which carries at one end the movable wedge-shaped contact member 20 for movement into and from electrical contact with the stationary contact assemblies l2, 14 to provide current flow therebetween. The contact operating rod 18 may be moved from the open to the closed circuit position manually by operation of the manual operating handle mechanism 22 (only partially shown), the movement of which is translated to motion of the operating rod [8 by the toggle-type operating mechanism.

The operating mechanism of the center pole 4 in the illustrated embodiment includes a releasable cradle 24 which has a latch portion 26 at one end and which is supported for pivotal movement upon a pivot 25 and held in latched position against pivotal movement by the latch member 27 which is pivotably mounted on the pivot 29. A pair of toggle links 28 (only one of which is shown) is positioned on opposite sides of the cradle 24 and is connected thereto by a pivot pin 31. A pair of lower toggle links 34 (only one of which is shown) is connected at its upper end to the upper toggle links 28 bythe pin 36. A pair of tension springs 44 (only one of which is shown) connects the pin 36 to the manual operating handle mechanism 22.

This embodiment of the invention utilizes a multipole type operating mechanism of the type described and claimed in Johnson et al. US. Pat. No. 3,384,845 granted on May 2|, 1968 and assigned to the assignee of the present invention. Accordingly the operating mechanism in each of the circuit breaker poles includes a pair of movable actuator plates 40 (only one of which is shown in FIGS. 1 and 2) which are pivotably supported on the casing 10 by the pivot pin 42. In the center pole 4, the lower ends of the lower toggle links 34 are connected by the pivot pin 38. The operation of the operating mechanism of the central pole 4 of the three-pole breaker assembly serves to operate the movable contacts of all three poles by connection of the actuator plates 40 in the center pole 4 and corresponding actuator plates 40 in the chambers of the poles 2, 6 by means of insulating tie bar 74 which extends through apertures in the barrier sidewalls of the casing 10 between the center and outer poles.

The contact operating rod 18 is bifurcated adjacent the movable contact 20 and straddles a portion of the high speed connecting link or latch 46 and is connected thereto by the pin 48 which extends through a vertically elongated aperture 50 therein. The pin 52 is supported in fixed position on the casing 10 and extends through arcuate slots 54 in the contact actuator plates 40 and arcuate slot 56 in the latch 46. The slots 54 and 56 are dimensioned and configured to provide clearance for movement of the pin 52 therein and to act as a stop or limit for the actuator plates 40 in the open and closed circuit positions thereof. The latch 46 is configured to provide a pair of vertically spaced, horizontally extending shoulder portions 58, 60 upon which rides the roller 62 which is carried by the shaft 64 seated in the actuator plates 40.

The depending angular portion 66 on the latch 46 is engaged with one end of a tension spring 68 which has its other end connected to the pin 70 extending between the actuator plates 40. In this manner, the latch 46 is biased counterclockwise about the pin 48 (as seen in FIG. 2) to retain the roller 62 upon the shoulder portion 60 of the latch 46 during normal operation.

Automatic operation of the contact operating rod 18 from closed to open circuit position may be effected rapidly upon the occurrence of a high short circuit current by means of magnetic action of the solenoid coil 32 upon the primary armature or plunger 76 which is secured by the fastener 77 on the end thereof opposite that carrying the movable contact 20. As best seen in FIG. 2, the coil 32 is disposed about the tubular sleeve 78 in which the primary armature 76 is slidable, and current flowing therethrough generates a magnetic field acting upon the primary armature 76. When a high short circuit cur rent of predetermined magnitude passes through the solenoid coil 32, the magnetic force acting upon the armature 76 is sufficient to draw the operating rod l8 from the full line position shown in FIG. 2 to the phantom line position thereof, thus effecting movement of the movable contact 20 from the contact assemblies l2, l4 and breaking the circuit. The action of the operating mechanism upon such movement of the operating rod 18 will be described in detail hereinafter.

According to the present invention, the contact operating rod 18 may also be moved from the closed to open circuit position by a lesser, but more precisely predeterminable, short circuit current passing through the solenoid coil 32. A trip or secondary armature 80 is slidably supported in the guide member 82 adjacent the solenoid coil 32 and is subject to the magnetic force generated by current flowing therethrough so as to be attracted thereto.

As best seen in FIGS. 5 and 6, the latch release member generally designated by the numeral 86 is pivotably supported in the casing by the common trip rod 88 and it has a hookshaped latch portion 90 which abuts the latch member 27 to prevent its pivoting. The latch release member 86 has a depending portion 92 which is engageable by the L-shaped trip member 94 which is secured to the secondary armature 80 by brazing or the like. Attached to the trip member 94 is one end of the tension spring 96 which has its other end connected to the spring adjustment lever 98 which is pivotably supported at its upper end in an aperture 100 of the air gap adjusting lever 102. The cars 104 on the adjusting lever 102 are pivotably seated in apertures 106 formed in the side legs of the generally U-shaped mounting bracket 108 which is secured to the casing 10. The spacing or angle between the airgap adjusting lever I02 and the spring adjustment lever 98 and thereby the tension of the spring 96 may be varied by movement of the adjusting screw 110 threadably in the spring adjusting lever 98.

A resilient stop for the spring adjusting lever 98 is provided by the compression spring 112 which is seated in a recess 114 in the casing 10. The airgap adjusting lever 102 may be pivoted in the mounting bracket 108 by the cam member 116 which is eccentrically supported on the adjusting rod I18 by the threaded fastener 119 to which it is secured by brazing or the like. The lower end of the adjusting rod 118 is journaled in the web portion of the U-shaped mounting bracket 108 and the upper end is slotted (as best seen in FIG. 4) and extends through an aperture I in the casing l0. Mounted on the upper end ofthe adjusting rod 118 within the recess 124 of the casing is an adjustment button 122 which is press fit thereon after calibration. The adjusting rod 118 is secured within the casing 10 against axial movement by the snap ring 126.

The operating mechanism in each of the outer poles 2, 6 is generally similar to that illustrated for the pole 4 except that it does not include a handle assembly 22. cradle 24, latch member 27, and the toggle linkage provided by the elements 28, 34 and springs 44. Thus, operation of the mechanism therein is effected by pivoting of the contact actuator plates 40 thereof by the tie bar 74 as a result of pivoting of the actuator plates 40 in the center breaker 4 or by magnetic tripping as a result of movement of the armatures 76 or 80 resulting from a short circuit current passing through the solenoid coils 32 thereof.

Operation of the Breaker Mechanism Upon Occurrence of a High Short Circuit Current As previously indicated, the current flowing through the solenoid coil 32 produces a magnetic force acting upon the primary armature 76 which is carried by the contact operating rod l8. When the short circuit current in any one of the circuit breaker poles reaches a predetermined value, the magnetic source generated by the solenoid coil 32 is sufficient to draw the primary armature 76 thereto at high speed and to open the circuit through movement of the contact operating rod 18 and the movable contact 20 away from the stationary contact assemblies l2, 14. The motion of the contact operating rod 18 is transmitted to the latch 45 by reason of the engagement of the pin 48 therewith. As will be appreciated, the latch 45 rotates in a clockwise position about the pin 52 against the biasing action of the spring 68-, thus moving the shoulder 60 below the level of the roller 62. As the roller 62 clears the shoulder 60, the latch 46 slides to the right under the influence of the spring 68 and the magnetic force of the solenoid coil 32 acting upon the armature 76. The roller 62 then seats against the shoulder 58 of the latch 40. In this manner, the operating rod 18 is moved rapidly by magnetic action with minimum inertial resistance of the operating mechanism, thus effecting high speed opening. 7

As will be readily appreciated, a short circuit current of sufficient magnitude to draw the primary armature 76 to the solenoid 32 and open the contacts in any one of the pole chambers will also draw the secondary armature towards the solenoid coil 32. This movement causes the trip member 94 to strike the depending portion 92 of the latch release member 86 to effect pivoting of the l8tch release member 86 in the center pole 4. This in turn releases the latch member 27 so that the biasing pressure of the automatic operating mechanism therein will pivot the cradle 24, collapsing the toggle mechanism and causing pivoting of the contact actuator plates 40 in the center pole chamber and thereby the contact actuator plates 40 in each of the outer poles since they are connected together by the tie bar 74. As a result, the contact operating rod 18 in each of the poles is moved to open circuit position.

Thus, high speed opening of the circuit breaker under the solenoid action in any of the pole chambers will effect opening of the contacts in the other pole chambers. in addition, the operating. mechanism will be tripped to the trip indicating position, and the operating mechanism may be reengaged with the operating rod 18 for reclosing of the circuit.

Adjustment of the Magnetic Trip Level in the structure of the present invention, the magnetic trip level may be closely adjusted so as to permit functioning of the breaker at both a high and a low setting, both of which may be closely calibrated. Typically, such settings may be at 6 and 12 times the rating of the breaker or 600 and I200 amperes for a ampere breaker. Generally, such calibration will be effected at the factory at the time of assembly of the circuit interrupter so that precision test apparatus may be utilized therefor. Once this calibration has been effected, the circuit breaker may be adjusted in the field to either a high setting or a low setting as may be required by the particular installation.

ln efl'ecting calibration and adjustment of the interrupter, the adjusting rod 118 is rotated to a high setting representing essentially a maximum airgap between the secondary armature 80 and the solenoid coil 32 wherein the cam member 116 is at its maximum radius of curvature. Normally, the maximum airgap or high setting will occur when the airgap adjustment lever 102 has its principal portion extending parallel to the axis of the adjusting rod 118.

In this position, the spring biasing force is now closely set by rotation of the adjusting screw which varies the angle of spacing between the adjusting levers 98, 102 and thus the length and tension force of the spring 96. When a spring force is reached which will just balance the magnetic attraction exerted by the solenoid coil 32 upon the secondary armature 80 and below which operation is not desired, the high setting of the breaker has thus been established.

Having now established the desired level of spring force, the cam member 116 is rotated about the adjusting rod 118 to the reduced radius so as to permit the airgap adjusting lever 102 to pivot towards the solenoid coil 32. A wrench or other suitable means is then utilized to hold the cam member 116 stationary while the adjusting rod 118 is rotated to produce movement of the cam member-l l6 upwardly or downwardly along the length of the adjusting rod 8 until the desired low setting is attained in which the spring force will just balance the magnetic force exerted by the solenoid coil 32 at some lesser value of current flow. It can be seen that this movement of the cam member "6 varies the angular relationship of the airgap adjusting lever 102 relative to the axis of the adjusting rod 118 and thus causes the free end of the adjusting lever 102 to move towards or away from the solenoid coil 32 with concurrent movement of the secondary armature 80 as a result of the biasing action of the spring 96. As a result, the airgap between the primary armature 76 and secondary armature 80 is reduced so as to increase the magnetic force acting upon the secondary armature 80 at a given current flow through the solenoid coil 32.

Thus, the spring force remains constant although the airgap is reduced at the low setting to permit operation of the breaker mechanism through the secondary armature 80 at a lower level of short circuit current flow. After the adjustment has been made the wrench is removed and the adjustment button I22 is press fit onto the exposed end of the adjusting rod "8. Thereafter, rotation of the adjustment button 122 will produce rotation of the cam member 116 only between the precalibrated high and 149 settings with the spring pressure remaining essentially constant.

Operation of the Breaker Mechanism Upon Occurrence of a Short Circuit Current of Lesser Magnitude As will be appreciated, the adjustment mechanism for the tension spring 96 acting upon the secondary armature 80 may be relatively closely adjusted to permit operation of the breaker mechanism upon the occurrence of a short circuit current of lesser magnitude than that required to effect movement of the contact operating rod 18 independently of the operating mechanism. If the short circuit current flowing through the solenoid coil 32 exceeds the calibrated value established by the adjustment of the tension spring 96 through the spring adjustment lever 98 and the airgap setting established by the position of the cam member 116, the secondary armature 80 will be drawn inwardly of the solenoid coil 32 to effect circuit opening action. In either form of magnetic operation, the armatures 76, 80 act as the stator elements for magnetic action upon each other.

This movement of the armature 80 will in turn produce pivoting of the latch release member 86 in a clockwise direction by engagement therewith of the trip member 94.

This pivoting in turn releases the latch member 27 so that itmay pivot in a clockwise direction under the biasing pressure of the toggle springs 44. As a result, the cradle 24 will pivot and the toggle linkage will produce pivoting of the contact actuator plates 40 about their pivot pin 42 in a clockwise direction with resultant movement of the contact operating rod 18 to the open circuit position. As the contact actuator plates 40 of the center pole 4 pivot, the contact actuator plates 40 of the other poles 2, 6 simultaneously pivot because of the c4nnection of the tie bar 74 therebetween, thus effecting opening of the contacts in the outer poles 2,6.

In the multipole embodiment of the present invention illustrated, magnetic movement of the secondary armature 80 in either of the outer pole chambers 2.6 will effect pivoting of the latch release member 86 on the common pivot pin or shaft 88 'as hereinbefore described. In this manner, the operating mechanism of the center pole 4 will be tripped and the contacts will be opened in both the center pole chamber 4 and the remaining outer pole chamber.

The movement of the secondary armature 80 inwardly of the solenoid coil 32 will also tend to increase the magnetic force acting upon the primary armature 76. The resultant increased magnetic force may be sufficient to draw the primary armature 76 to the solenoid coil 32 for high speed magnetic action independently of the automatic operating toggle mechanism which is slower in action.

Although the present invention has been illustrated and described with respect to a multipole breaker, it will be readily appreciated that it is particularly adapted to single-pole breaker operation. Moreover. in multipole breaker constructions, each of the several poles may include automatic operating mechanism such as that illustrated herein for the center pole chamber.

As will be appreciated, various means may be used to provide the releasable interconnection between the automatic operating mechanism and the contact operating member so long as the connection may be overridden or released upon devel'opment of a magnetic force of predetermined magnitude as a result of a short circuit. Highly advantageous mechanisms are that illustrated herein and those described in the aforementioned Giger U.S. Pat. No. 3,495,198 and Hurtle U.S. Pat. No. 3,483,490.

Similarly, various other manual and automatic operating mechanisms may be employed in accordance with the present invention such as, for example, the manual operating mechanism shown in the aforementioned Hurtle U.S. Pat. No. 3,483,490. When the present invention is utilized in multipole breakers, theinterconnection of the several poles may be through-the common pivot for the latch as in the illustrated embodiment or other means may be employed such as a sliding rod extending between the secondary armatures through the barrier walls. Other techniques for effecting concurrent operation of the several poles are well known and understood and will be apparent to those having ordinary skill in the art.

In the illustrated embodiment, the airgap adjusting lever bears against the secondary armature to limit its movement toward the spring adjusting lever under the action of the spring. If so desired, other means to effect the limitation of movement may be employed, such as a collar or pin on the secondary armature abutting against the guide member 82.

If so desired, the circuit breaker may also include conventional thermal trip mechanism such as the bimetal strip type wherein a short circuit of low magnitude extending over a sufficient period of time will produce release of the latch mechanism of the automatic operating mechanism for opening of the contacts. Such devices may employ various means for effecting the releasing action such as by having. the bimetallic strip act upon the secondary armature to produce movement thereof towards the solenoid coil or by having it act upon the latch member directly or an element engaged therewith.

Thus, it can be seen from the foregoing detailed specification and drawing that the present invention provides a highly effective electric circuit interrupter which is capable of rapidly opening the contacts therein and wherein the magnitude of the short circuit current required for opening of the contacts may be relatively accurately predetermined. The airgap between the armatures may be varied between high and low settings without varying the spring tension force required to be overcome by the solenoid. The circuit interrupters of the present invention may be simply and economically constructed and the magnitude of the short circuit current required for tripping of the breaker may be varied between high and low settings with a high degree of accuracy so as to avoid spurious tripping.

What we claim as new and desire to secure by Letters Patent of the United States is:

We claim:

1. In an electric circuit interrupter, the-combination comprising:

a. a casing;

b. at least one stationary contact in said casing;

c. a movable contact;

d. a contact operating member carrying said movable contact adjacent one movable thereof;

e. means mounting said contact operating member for movement of said movable contact into and from contact with said stationary contact between closed and open circuit positions;

a first annature on said contact operating member adjacent the other end thereof;

g. a solenoid having one end thereof adjacent said first armature, said solenoid generating a magnetic force acting upon said first armature sufficient to draw said contact operating member into open circuit position upon passage of a short circuit current of predetermined magnitude therethrough;

h. a second armature adjacent the other end of said solenoid and attractable thereby;

i. means mounting said second armature in said casing for movement from a normal position towards said solenoid into a circuit opening position upon passage through said solenoid of short circuit current of predetermined magnitude; V

j. first lever means having one end pivotably mounted in said casing and having its free end extending towards the end of said second armature spaced from said solenoid;

. second lever means pivotably mounted on said first lever means adjacent said one end thereof and having its free end spaced from the side of said first lever means opposite that adjacent said second armature;

l. tension spring means biasing said second armature towards said free end of said second lever means, movement of said second armature towards said second lever being limited;

m. first adjustment means for varying the spacing between the free ends of said first and second lever means and thereby the biasing pressure of said tension spring means; and

n. second adjustment means for pivoting said first lever means and thereby varying the spacing between the second annature and said solenoid, the spacing between the free ends of said first and second lever means remaining essentially constant during said pivotal movement effected by said second adjustment means.

2. The circuit interrupter of claim I wherein said free end of said first lever means bears against said second armature to limit its movement toward said second lever means and wherein said tension spring means is connected between said second armature and said second lever means.

3. The circuit interrupter of claim 2 wherein said first adjustment means is a threaded member threadably engaged in one of said lever means and abutting against the other of said lever means.

4. The circuit interrupter of claim 1 wherein there is included:

0. means in said housing operable against said second lever means to bias the assembly of said first and second lever means towards said solenoid.

5. The circuit interrupter of claim I wherein said second adjustment means includes a rotatable cam member bearing against said first lever means to produce pivotal movement thereof upon rotation.

6. The circuit interrupter of claim 5 wherein said rotatable cam member comprises a cam mounted upon a shaft rotatably supported in and extending outwardly of said casing to permit rotation of said cam for pivotal movement of said first lever means.

7. The circuit interrupter of claim I wherein there is included:

p. operating means connnected to said operating member for automatically moving said contact operating member from closed to open circuit position; and

q. releasable means latching said operating means against said automatic movement, said second armature acting upon said latching means in movement thereof to said circuit opening position to release said operating means for automatic operation thereof.

8. The circuit interrupter of claim 7 wherein said second ar mature has a trip member thereon engageable with said latching means to release said operating means.

9. The circuit interrupter of claim 7 wherein said operating means includes releasable connecting means between said operating means and said contact operating member, said connecting means being releasable upon operation of said first armature by said solenoid to permit movement of said contact operating member to open circuit position independently of the operating means.

10. The circuit interrupter of claim 7 wherein said operating means includes a pivotable cradle, a toggle mechanism biasing said cradle for pivotal movement upon release of said latching means and releasable means connecting said toggle mechanism to said contact operating member for movement thereof into open circuit position upon pivoting of said cradle, said connecting means being releasable upon operation of said first armature by said solenoid to permit movement of said contact operating member to open circuit position independently of the operating means.

11. The circuit interrupter of claim 1 wherein said mounting means for said second annature includes a guide member in said casing in which said second armature is slidably seated.

12. The circuit interrupter of claim 1 wherein said tension spring means is connected between said second armature and said second lever means and wherein there is included:

i 0. means in said housing operable against said second lever means to bias the assembly of said first and second lever means towards said solenoid.

13. The circuit interrupter of claim 12 wherein said second adjustment means includes a rotatable cam member bearing against said first lever means to produce pivotal movement thereof upon rotation.

14. The circuit interrupter of claim I wherein said tension spring means is connected between said second armature and said second lever means, wherein said second adjustment means includes a rotatable cam member bearing against said first lever means to produce pivotal movement thereof upon rotation, and wherein there is additionally included:

p. operating means connected to said operating member for automatically moving said contact operating member from closed to open circuit position; and I q. releasable means latching said operating means against said automatic movement, said second annature acting upon said latching means in movement thereof to said circuit opening position to release said operating means for automatic operation thereof.

15. A multipole electric circuit interrupter comprising:

a. a casing providing a plurality of pole chambers;

b. at least one stationary contact in each pole chamber; c. a movable contact in each pole chamber;

d. a contact operating member in each pole chamber carrying the movable contact adjacent one end thereof;

e. means in each pole chamber mounting said contact operating member for movement of said movable contact into and from contact with said stationary contact between closed and open positions;

. a first armature on each of said contact operating members adjacent the other end thereof;

g. a solenoid in each pole chamber having one end thereof adjacent said first armature, said solenoid generating a magnetic force acting upon said first armature sufficient to draw said contact operating member into open circuit position upon passage of a short circuit current of predetermined magnitude therethrough;

h. a second armature in each of said pole chambers adjacent the other end of said solenoid and attractable thereby;

i. means in each of said pole chambers mounting said second armature therein for movement from a normal position spaced from said solenoid and towards said solenoid into a circuit opening position upon passage through said solenoid of a short circuit current of predetermined magnitude;

j. first lever means in each of said pole chambers having one end pivotably mounted in said casing and leaving its free end bearing against the end of said second armature spaced from said solenoid;

k. second lever means in each of said pole chambers pivotably mounted on said first lever means adjacent said one end thereof and having its free end spaced from the side of said first lever means opposite that hearing against said second armature;

. tension spring means in each of said pole chambers biasing said second armature towards said free end of said second lever means and against said first lever means;

. m. first adjustment means in each of said pole chambers for varying the spacing between the free ends of said first and second lever means and thereby the biasing pressure of IS said tension spring means;

n. second adjustment means in each of said pole chambers for pivoting said first lever means and thereby varying the spacing between the second armature and said solenoid, the spacing between the free ends of said first and second lever means remaining essentially constant during said pivotal movement effected by said second adjustment means;

0. operating means in one of said pole chambers connected to said operating member for automatically moving said contact operating member from closed to open circuit position;

p. releasable means in said one pole member latching said operating means against said automatic movement, said second armature acting upon said latching means in movement thereof to said circuit opening position to release said operating means for automatic operation thereof; and

q. means in the other of said pole chambers operable upon said releasable means of said one pole chamber upon movement of the second armature in said other pole chambers to effect release thereof and automatic operation of said operating means.

16. The circuit interrupter of claim 15 wherein said tension spring means is connected between said second armature and said second lever means.

l7. The circuit interrupter of claim l5 wherein said second adjustment means includes a rotatable cam member bearing against said first lever means to produce pivotal movement thereof upon rotation.

18. The circuit interrupter of claim 15 wherein said tension spring means is connected between said second armature and said second lever means. wherein said second adjustment means includes a rotatable cam member bearing against said first lever means to produce pivotal movement thereof upon rotation, and wherein said operating means includes releasable connecting means between said operating means and said contact operating member, said connecting means being releasable upon operation of said first armature by said solenoid to permit movement of said contact operating member to open circuit position independently of the operating means.

[9. The circuit interrupter of claim 15 wherein said operating means includes a pivotable cradle, a toggle mechanism biasing said cradle for pivotal movement upon release of said latching means and releasable means connecting said toggle mechanism to said contact operating member for movement thereof into open circuit position upon pivoting of said cradle, said connecting means being releasable upon operation of said first armature by said solenoid to pennit movement of said contact operating member to open circuit position independently of the operating means.

20. The circuit interrupter of claim 15 wherein said second armatures each have trip members thereon engageable with a common trip pivot shaft extending in each of said pole chambers and pivotably mounting said latching means in said one pole chamber, whereby movement of the trip member in any one of the pole chambers will effect pivoting of said latching means.

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