US3495198A

US3495198A - Electric circuit breaker with releasable coupling mechanism

Info

Publication number: US3495198A
Application number: US747690A
Authority: US
Inventors: Walter Giger Jr
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1968-07-25
Filing date: 1968-07-25
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10

Description

. ELECTRIC .CIRGUIT BREAKER WITH RELEASABLE courune MECHANISM Filed July 2-5, 1968 W. GIGER, JR

Feb; 10, 1970 2 Sheets-Sheet l mvavron: WALTER 6/GER,JR., 57 WW A770 MECHANISM Feb; 10, 1970' w. me a JR ELECTRIC CIRCUIT BREAKER WITH RELEASABLE COUPLING 2 Sheets-Sheet 2 v Filed July 25, 1968 MAM 06 M WM m #1 M By f United States Patent O 3,495,198 ELECTRIC CIRCUIT BREAKER WITH RELEASABLE COUPLING MECHANISM Walter Giger, Jr., Wethersfield, Conn., assignor to General Electric Company, a corporation of New York Filed July 25, 1968, Ser. No. 747,690 Int. Cl. Htllh 75/00 US. Cl. 335-16 14 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker has a movable contact carried by a contact operating member and automatic operating means and manual operating means for effecting movement of the contact operating member from closed to open circuit position. Disengageable means is provided to couple the manual operating means to the contact operating member for normal operation thereof, but the coupling means is disengageable upon operation of the automatic operating means to permit movement of the contact carrying member independently of the manual operating means. The coupling means utilizes a resiliently deflectable member carried within a coupling member on the contact operating member and a convexly arcuate projection on one of these members normally seated in a recess in the other member.

BACKGROUND OF THE INVENTION The increasing use of electric power for various purposes has produced a requirement for electric power supply systems of ever increasing capacity and a concurrent requirement for circuit breakers capable of interrupting the high short circuit currents which can occur in such power systems. Moreover, it has been recognized that it is desirable to prevent the short circuit current from attaining a magnitude during interruption which approaches the prospective short circuit current maximum since even the interrupted short circuit current may cause damage to other circuit components.

As a result there have been developed a number of electric circuit breaker devices having the ability to interr'upt a rising short-circuit current with a current-limiting action. A current limiting circuit breaker of the type referred to is disclosed in the copending application, Ser. No. 447,557, now abandoned, of Hurtle and Willard, filed May 21, 1965 and assigned to the same assignee as the present invention.

As disclosed in the aforementioned Hurtle and Willard application, it is highly desirable in such current limiting circuit breakers to open rapidly the contacts of the circuit breaker, thereby drawing the arc quickly and bringing into existence a highly resistive current limiting arc. Operation of the movable contact is desirably free from movement of the relatively massive elements of the switching mechanism so that the inertia of the system does not detract from rapid opening. To this end, the Hurtle and Willard device includes a disengageable coupling between the manual operating mechanism and the contact operating rod.

It is an object of the present invention to provide a novel circuit breaker which is capable of rapidly opening the contacts independently of operation of the manual operating mechanism and which may be simply and economically constructed.

It is also an object to provide such a circuit breaker wherein the elements are normally held firmly in assembly for manual operation but readily disengageable upon actuation of automatic operating means functioning in response to a short circuit current of high magnitude.

Another object is to provide such a circuit breaker which may be readily assembled and disassembled and which is capable of long lived operation and ready variation in the magnitude of short circuit current required for automatic operation.

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 containing a stationary contact and a movable contact with a contact operating member carrying the movable contact at one end thereof. Means in the casing mounts the contact operating member for movement of the movable contact between closed and open circuit positions, and automatic operating means connected to the contact carrying member provides for movement thereof from closed to open circuit position upon passage of a short circuit current of predetermined magnitude therethrough. Manual operating means is provided on the casing and coupling means connects the manual operating means to the contact operating member for movement thereof between closed and open circuit positions. I

The coupling means includes a coupling member about the contact carrying member and means engaging the coupling member to the manual operating means for translation of movement therefrom. A disengageable connection between the coupling member and the contact carrying member is provided and includes a deflectable member disposed about the contact carrying member within the coupling member and supported or carried by one of the contact carrying and coupling members for movement relative to the other. At least one convexly arcuate projection of circular cross section is provided upon either the defiectable member or the member as to which it is relatively movable, and at least one cooperating recess is provided in the cooperating surface of the other of these members for receiving the projection in the closed circuit position. This connection is normally operative to provide for operation of the contact carrying member in response to movement of the manual operating means; however, the convexly arcuate projection provides a camming surface facilitating movement outwardly of the recess in which it is received and resultant deflection of the defiectable member upon operation of the automatic operating means. As a result, a sudden force on the contact carrying member causes the projection to move outwardly of the recess to disengage the coupling means. This permits rapid movement of the contact carrying member from closed to open circuit position independently of the coupling member and the manual operating means since the inertia of these more massive operating elements does not have to be overcome.

Generally, the convex projection is most conveniently provided by a spherical element or ball retained so as to permit it to rotate upon relative movement. This enhances the facility with which the projection may escape from the recess and minimizes friction between the projection and the surface along which it moves thereafter.

BRIEF DESCRIPTION OF THE DRAWINGS illustrating the movable elements of the circuit breaker 3 of FIGURE 1 in the closed circuit condition and with the tubular support broken away to show the position of the armature;

FIGURE 3 is a view similar to FIGURE 2 illustrating the movable elements in the condition assumed upon operation by a high short circuit current;

FIGURE 4 is a transverse sectional view of one embodiment for the detent mechanism of the circuit breaker of FIGURE 1 along the line 4-4 thereof and to a greatly enlarged scale;

FIGURE 5 is a longitudinal sectional view of the embodiment of detent mechanism illustrated in FIGURE 4;

FIGURE 6 is an exploded fragmentary perspective view of the parts thereof;

FIGURE 7 is a view similar to FIGURE 4 of another embodiment of detent mechanism; and

FIGURE 8 is a view similar to FIGURE 5 of the embodiment of FIGURE 7.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning first in detail to FIGURES l-3, therein illustrated is a circuit breaker having an insulating casing generally designated by the numeral 10

side walls

12, 14 and a top wall 16. Mounted in the casing by suitable means (not shown) is a pair of spaced stationary contact assemblies generally designated by the

numerals

18, 20 and which have

opposed contact faces

22, 24 adjacent their inner end and diverging

arc runner portions

26, 28. Movable into and away from contact with the contact faces 22, 24 are the contact faces 30, 32 of the generally wedge-shaped movable contact member generally designated by the numeral 34 carried on the end of the elongated contact operating rod 36. Received between the

inner end portions

38, 40 of the

stationary contact assemblies

18, 20 is a generally cup-shaped insulating member 42 which provides a pressure chamber 44 about the area of movement of the movable contact member 34 and which has a close fitting aperture 46 in the end wall thereof in which the contact operating rod 36 is slidable.

A line terminal 48 on the casing 10 supplies current to the conductive strap 50 which is electrically connected to the stationary contact assembly 18 by the line indicated diagrammatically and designated by the numeral 52. As pointed out in the aforementioned Hurtle and Willard application, a blow out coil is desirably included in the line 52. The stationary contact assembly 20 is electrically illustrated by the block 54 by the line indicated diagrammatically and designated by the numeral 56, which desirably also includes a blow out coil. The trip unit 54 is connected by the line 58 to the solenoid 60 which in turn is connected to the strap 62 of the load terminal 64 by the line 66.

As a result, the current path through the circuit breaker is from the line terminal 18 to the strap 50 and thence through the line 52 to the stationary contact assembly 18. When the movable contact member 34 is in closed circuit position, the current flows from the contact face 18 to the contact face 30 of the movable contact member 34 and thence to the contact face 20. Since the face 20 is connected by the line 56 to the thermal trip unit 54, the current flows therethrough and thence to the solenoid 60 through the line 58. Finally the current passes through the line 66 to the strap 64 of the loaded terminal 64.

In accordance with conventional practice, the breaker includes manual operating means for moving the contact operating rod 36 into and from closed circuit position with the contact faces 22, 24 which includes a manually engageable handle member 68 projecting outwardly through an aperture 70 in the top wall 16 of the casing 10. The generally inverted U-shaped handle support member 72 With n he c si g 10 has slots 74 in the free ends of its legs which pivotably seat on the fixed pins 76 on the

sidewalls

12, 14 of the casing 10 so as to be pivotable between the positions shown in FIGURES 1 and 2 of the drawings. A pair of connecting links 78 are pivoted at their upper end by the pins 80 to the releasable cradle generally designated by the numeral 82 and have elongated slots 8-4 at their lower ends which receive pivot pins "86 on the side of the coupling member 88. A pair of operating springs are connected at their upper ends to pins on the upper portion of the handle support member 72 and at their lower ends to the connecting links 78 to provide a toggle action.

When the parts are in the on condition shown in FIGURE 2, the line of action of the operating springs 90 lies to the left of the pivot pins 80' as viewed therein or to the side of the pins '80 spaced towards the

contact assemblies

18, 20. The biases the connecting links 78 clockwise about the pivot pins 80 and urges the coupling members 88 and thereby the contact operating rod 36 and movable contact member 34 into firm electrical contact with the stationary contact faces 22, 24. When the handle member 68 is moved to the off position shown in FIGURE 1, the line of action of the springs 90 is to the right of the pivot pins '80 as viewed therein or to the side of the pins 80 spaced away from the

contact assemblies

18, 20. This biases the operating links 78 counterclockwise about the pivot pins 80 and urges the coupling member 88 and thereby the contact operating rod 36 and movable contact member 34 away from electrical contact with the stationary contact faces 22, 24.

The generally L-shaped releasable cradle 82 is pivotably mounted at one end by the pin 92 and is held against rotation in a counterclockwise direction by the latch 94 of the diagrammatically illustrated trip unit 54. In its usual aspect, the trip unit will employ a bimetallic strip or other means responsive to a sustained short circuit current of relatively low magnitude which results in movement of the latch 94 to release the cradle 82. In some instances, the trip unit 54 may be, either solely or a combination with, a common trip mechanism operated by another circuit breaker pole or section. Upon release of the cradle 82 when the elements are in the on position shown in FIGURE 2, the operating springs 90 produce pivoting of the connecting links 78 and the cradle 82 in a counterclockwise direction about the pin 92. This in turn produces movement of the contact operating rod 36 away from the

stationary contact assemblies

18, 20 to open the

contacts

22, 24, 30, 32.

As best seen in FIGURES 2 and 3, the contact operating rod 36 carries a solenoid plunger 96 at its end which is slidably received in the tubular sleeve 98 fixedly mounted in the casing 10. On passage of a high short circuit current of a predetermined magnitude through the solenoid 60, the magnetic force of the solenoid and the rapidity of action are sufficient to disengage the releasable connection between the coupling member 88 and the contact operating rod 36 and draw the operating rod 36 away from the

contact assemblies

18, 20 to open the contacts rapidly. The solenoid plunger 96 strikes against the resilient stop cushion 100 of neoprene or the like which protects the field piece 102 of the solenoid.

One type of disengageable connection within the scope of the present invention is illustrated in FIGURES 4-6. In this embodiment, the contact operating rod 36 has a pair of spaced

apertures

104, 106 along the length thereof, and the coupling member 88 has a laterally extending chamber 108 intermediate the length thereof communicating 'With the central passage 110 through which the contact operating rod 36 extends. A generally U-shaped spring clip generally designated by the numeral 112 is seated in the passage 110 of the coupling member 88 and has legs 114 outwardly disposed wings, 116, received in the chambers 108 to lock the clip therein against longitudinal movement, but the chambers 108 are dimensioned to permit spreading of the legs 114 and wings 116 of the clip 112. The legs 114 are provided with cutouts 118 therein which seat small steel balls 121).

In normal operation of the circuit breaker, the steel balls 120 also seat partially within the apertures 106 of the contact operating rod 36 since these apertures are of lesser diameter than the balls 120. Upon rapid actuation by the passage of a short circuit current through the solenoid 60, the force on the operating rod 36 causes the steel balls 120 to cam against the side of the aperture 106 and to ride outwardly therefrom while at the same time deflecting the legs 114 of the spring clip 112. This allows the operating rod 36 to move freely of the coupling member 88 and the remainder of the operating mechanism and thus be free of the inertia thereof. As the contact operating rod 36 moves toward the cushion 100, the balls 120 roll along the surface of the rod 36 until they drop into the aperture 104 to prevent the contact rod 36 from bouncing back and reclosing the contacts.

Turning now to the embodiment of FIGURES 7 and 8, a single steel ball 130 is press fitted into the aperture 132 of the contact operating rod 36. The spring clip generally designated by the numeral 134 is retained within the coupling member 88 and has reversely

bent legs

136, 138 provided with apertures 140 in the inner portions thereof and of lesser diameter than the steel ball 130 which partially seats therein. When the solenoid 60 actuates the operating rod 36, the ball 130 bears against the sides of the apertures 140 and rides outwardly therefrom as it spreads the

legs

136, 138. The contact operating rod 36 thus moves freely of the coupling member 88 and the remainder of the operating mechanism except for the frictional biasing pressure of the spring clip 134. After the ball 130 has passed outwardly of the spring clip 134, the deflection produced thereby is terminated and the

legs

136, 138 close against the side surfaces of the contact operating rod 36 behind the ball 130 and thus provide an abutment preventing the rod from bouncing back and reclosing the contacts. Alternatively, the spring clip 134 may be of greater length and provided with a second aperture to receive the ball 130 in the operated or open condition.

The configuration and characteristics of the resiliently defiectable member are selected with respect to the convexly arcuate projections and cooperating recesses so that the force exerted thereby will normally maintain the projections seated in the recesses. Operation of the handle member 68 will produce movement of the contact operating rod 36 between open and closed circuit positions. Although the solenoid 60 is exerted a magnetic force on the solenoid plunger 96 at all times during current flow through the breaker, it is generally a gradually altering force. In an instance of a sudden short circuit current of the rated magnitude, a magnetic force of sufficient magnitude (generally suddenly) overrides the spring force to cam the clip or

defiectable member

112 or 134 sufficiently to release the projection from the cooperating recess as it draws the rod 36 axially towards the solenoid 60. Although the force of the solenoid 60 under the predetermined conditions for automatic tripping is much greater than that of the operating springs 90, the manual operating mechanism is not moved to the open circuit position when this occurs. Instead, the contact operating rod 36, the solenoid plunger 96 and the movable contact member 34 move without being impeded by the inertia of the elements of the manually operable mechanism although the coupling member 88 remains in substantially the same position. The defiectable member or

clip

112, 134 slides along the surface of the cooperating member and then biases the projections into the second recesses to retain the movable contact assembly from 6 moving back or rebounding toward closed circuit position.

Following automatic opening, the mechanism may be reset to permit reclosing simply by moving the operating handle member 68 to its normal off condition, thereby returning the projection member 116 into engagement in the recess in the closed circuit or initial position. The circuit breaker may then be reclosed by returning the handle member 68 to its on position as shown in FIG- URE 2.

Although the convexly arcuate projection may be integrally formed in its associated member, it has been found highly advantageous to utilize a spherical member such as a steel ball to provide this surface projection. Depending upon the nature of the parts and the configuration thereof, the steel ball may be seated within a cooperating aperture in its associated member so as to rotate freely therein. By such freedom to rotate, the facility with which the projection may escape from the recess in the cooperating member is greatly enhanced and the friction between the projection and the surface of the cooperating member along which it moves thereafter can be greatly minimized. However, the spherical member may be press fit into an aperture in its associated member albeit with a loss in the desirable rolling action. In place of polished steel balls, spherical elements of other materials such as brass, tetrafiuoroethylene and polyamide may be utilized for even greater reduction in friction.

As will be readily appreciated, the resiliently defiectable member may be carried by either the coupling member or the contact operating member for movement therewith relative to the other. When the resiliently defiectable member is carried by the coupling member, it will operate in tension; when it is carried by the contact carrying member, it will operate in compression. In the former instance, the projection and cooperating recess will be located on the opposed surfaces of the defiectable member and contact operating member; in the latter instance, the projection and recess will be located in the opposed surfaces of the defiectable member and coupling member.

Generally, the resiliently defiectable member is desirably confiured to provide leg portions on opposite sides of the contact operating rod or thereby enabling the provision of cooperating projections and recesses for the coupling along both side surfaces of the operating rod. In one advantageous embodiment illustrated in FIGURES l-6, the clip has a generally U-shaped configuration with portions of the legs being disposed outwardly to provide means for engagement with the coupling member to secure it therein. However, the resiliently defiectable member may also assume other forms such as the reversely bent clip shown in FIGURES 6 and 7 of the attached drawings. If so desired, separate spring elements may be provided on either side of the contact operating rod and these, of course, may assume a variety of configurations.

The member having the recess for receiving the convexly arcuate projection is desirably provided with a second recess in the open circuit position of the contact operating member so as to hold that member in the open circuit position against any tendency for the contact operating member to bounce back and reclose the contacts. Desirably, the recess is similar in configuration to that provided in the closed circuit position so that the same camming action may be utilized to facilitate disengagement therefrom for movement manually of the contact operating member into closed circuit position and reengagement of the convexly arcuate projection in the recess corresponding to the closed circuit position. However, a shoulder or rib may also be utilized.

Other types of manual operating mechanism may also be employed in accordance with the present invention so long as it produces opening and closing movement of the contact operating rod. In addition, other types of tripping elements may be combined therewith including common trip units effecting movement of the manual operating mechanism in response to operation of a coupled circuit breaker.

Although the present invention may be utilized in any circuit interrupter where extremely rapid opening of the contacts is desired upon passage of a high short circuit current therethrough, it is particularly advantageously employed in current limiting type circuit breakers where ultra-high-speed opening movement of the contact is desired. Illustrated and described in the aforementioned Hurtle and Willard application, Ser. No. 447,557, now abandoned are particularly preferable constructions for the solenoid, arc chutes and contact operating rod and details of operation of a current limiting circuit interrupter. A parallel assisted circuit interruption device utilizing such a circuit breaker is disclosed in the copending application of Hurtle, Ser. No. 542,806, now Patent No. 3,430,016 filed May 15, 1966 and assigned to the same assignee as the present invention.

Thus it can be seen that the present invention provides a novel circuit breaker capable of rapidly opening the contacts independently of operation of the manual ope ating mechanism. The devices may be simply and relatively economically constructed and are readily adapted to variation in the magnitude of the short circuit current required to effect uncoupling since the number and size of the cooperating recesses and projections and the pressure required to deflect the spring member may be adjusted to suit the needs of a given application.

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

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

(a) a casing;

(b) a stationary contact in said casing;

(c) a movable contact;

(d) a contact operating member carrying said movable contact at one end thereof;

(e) means mounting said contact operating member for movement of said movable contact between closed and open circuit positions;

(f) automatic operating means connected to said contact operating member for moving said contact operating member from closed to open circuit position upon passage of a short circuit current of predetermined magnitude therethrough;

(g) manual operating means; and

-(h) means coupling said manual operating means to said contact operating member for moving said contact operating member between closed and open circuit positions, said coupling means including a coupling member about said contact operating member, means engaging said coupling member and said manual operating means for translation of movement thereby, and a disengageable connection between said coupling member and contact operating member, said disengageable connection including a resiliently deflectable member received within said coupling member and carried by one of said coupling and contact operating members for movement relative to the other, said connection also including at least one convexly arcuate projection on one of said members, the other of said deflectable and relatively movable members having a recess therein receiving said convexly arcuate projection in the closed circuit position to provide for operation of said contact operating member upon movement of said manual operating means, said convexly arcuate projection providing a camming surface upon movement relative to said recess and deflecting said deflectable member upon operation of said automatic operating means to release said projection from said recess and thereby to disengage said coupling means to permit movement of said contact operating member from closed to open circuit position independently of said coupling member and said manual operating means.

2. The circuit interrupter of claim 1 wherein said arcuate projection is provided by a generally spherical member carried by said one of said deflectable and the one of said coupling and contact operating members as to which it is readily movable.

3. The circuit interrupter of claim 1 wherein said recess in the other of said deflectable and relatively movable members is an aperture therein having a width less than the width of said convexly arcuate projection so that said projection only partially seats therein.

4. The circuit interrupter of claim 1 wherein said deflectable member is a clip-type element providing deflectable leg portions extending on opposite sides of said contact operating member.

5. The circuit interrupter of claim 1 wherein said deflectable member is carried by said coupling member for movement relative to the contact operating member and wherein said deflectable and contact operating members have the cooperating projection and recess therein.

6. The circuit interrupter of claim 1 wherein said deflectable member is a clip-type element providing leg portions extending to opposite sides of said contact operating member and carried by said coupling member for movement therewith relative to said contact operating member, at least one of said leg portions having an aperture therein seating a generally spherical member providing said convexly arcuate projection, said contact operating member having a recess therein of lesser diameter than the diameter of said spherical member to partially seat said spherical member.

7. The circuit interrupter of claim 6 wherein said contact operating member has a second recess therein to receive said spherical member in the open circuit position for retention of the contact operating member in said open circuit position.

8. The circuit interrupter of claim 1 wherein said contact operating member has a recess therein seating at least one spherical member providing said convexly arcuate projection and wherein said resiliently deflectable member is a clip-type element providing leg portions eX- tending on opposite sides of said contact operating member, said leg portions having apertures therein seating the projecting portions of said spherical member.

9. The circuit interrupter of claim 8 wherein said spherical member is of greater diameter than the thickness of said contact operating member so that portions of said spherical member project beyond both side surfaces of said contact operating member into engagement with said apertures in said leg portions of said deflectable member.

10. The circuit interrupter of claim 1 wherein said automatic operating means includes a solenoid on said casing and a solenoid plunger on said contact operating member attractable by said solenoid upon passage of a short circuit current of suflicient magnitude therethrough to overcome the force of said deflectable member.

11. The circuit interrupter of claim 1 wherein said deflectable member is carried by said contact operating member and is a clip-type member acting in compression and wherein said cooperating recess and arcuate projection are provided on said deflectable and coupling members.

'12. The circuit interrupter of claim 1 wherein said other of said deflectable and relatively movable members has a second recess therein receiving said convexly arcuate projection in the open circuit position to retain said contact operating member in said open circuit position.

13. The circuit interrupter of claim 1 wherein said deflectable member is a generally U-shaped clip-type ele ment providing leg portions extending on opposite side surfaces of said contact operating members with portions thereof being seated within said coupling member for movement therewith relative to said contact operating References Cited UNITED STATES PATENTS 2,763,739 9/ 1956 Forstrom. 3,315,189 4/1967 Heft 335l6 3,012,118 12/1961 Edmunds 335-16 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner US. Cl. X.R. 200-166