US2961510A

US2961510A - Operating mechanism for an electric circuit interrupter

Info

Publication number: US2961510A
Application number: US791106A
Authority: US
Inventors: Leslie L Baird
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1959-02-04
Filing date: 1959-02-04
Publication date: 1960-11-22
Anticipated expiration: 1977-11-22

Description

L.. L. BAIRD Nov. 22, 1960 OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4. 1959 5 Sheets-Sheet 1 Inventor: Leslie L.. Baird, 135g l 1His Attofneg.

L. E... BIRD Nov. 22, 1960 OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER 5 Sheets-Sheet 2 Filed Feb. 4, 1959 OPEN/N6 Inventor: Leslle L.. Baird, b S ls At vorweg.

Nov. 22, 1960 L. L. BAIRD 2,961,510

OPERATING MECHANTSM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 5 Sheets-Sheet 5 Inventor: Leslie L.. Baird,

b Hylsh Atorneg.

2,961,510 OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 4, 1959 L. L. BAIRD Nov. 22, 1960 5 Sheets-Sheet 4 CLOS/NG L. L. BAIRD Nov. 22, 1960 OPERATING MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER- 5 Sheets-Sheet 5 Filed Feb. 4. 1959 ITT/"8.9. f

Inventor: Leslie l.. Baird.t bgf Hs thorn eg.

United States Patent O OPERATIN G MECHANISM FOR AN ELECTRIC CIRCUIT INTERRUPTER Leslie L. Baird, Swarthmore, Pa.,

assignor to General Electric Company,

This invention relates to an electric circuit interrupter or breaker, and mo-re particularly it relates to a circuit ybreaker operating mechanism wherein a spring is arranged to release stored energy to the mechanism for obtaining quick-action circuit closing and opening operations.

Such stored energy mechanisms are commonly used in low-voltage air circuit breakers for driving a movable switch member between open and closed circuit positions. Mechanical energy is iirst accumulated in the spring by the controlled action of a movable operating member connected thereto. By moving the operating member from a reset position to an operated position with the mechanism in a releasably latched condition, the spring is stressed and accumulates energy the release of which imparts quick and positive switch closing movement to the mechanism.

The latched condition of a typical operating mechanism of this type is maintained by a latch which releasabiy restrains one member of the mechanism in a predetermined latched position. An unlatching operation enables the one member to move to an unlatched position, whereupon the operating mechanism collapses and circuit opening movement of the switch member is effected. In order subsequently to reset the mechanism in preparation for another closing operation, the one member is returned to its latched position.

It has been proposed to utilize electroresponsive means for moving the operating member of the above-described mechanism from reset to operated positions, thereby charging the mechanism spring. With this arrangement it is necessary to provide suitable switching means, such as a cutoff switch, for automatically deenergizing the electroresponsive means at the appropriate moment during the closing operation.

A general object of the present invention is to provide an improved circuit breaker operating mechanism of this type.

It is a more specific object of the invention to provide a circuit breaker having an operating mechanism of this type wherein the deenergization of the electro-responsive means is delayed until the final stages of the switch closing movement of the mechanism, thereby ensuring that the movable switch member of the breaker will close, and wherein reenergization of the electroresponsive means is prevented as long as the switch member is in its closed circuit position.

Another object of this invention is the provision of a breaker operating mechanism having means for maintaining the electroresponsive means deenergized whenever the aforesaid one member is in its unlatched position, thereby ensuring that the movable switch member is in its open circuit position and the mechanism is resetting before the electroresponsive means can be reenergized.

Still another object is the provision of an improved operating mechanism wherein the electroresponsive means is deenergized before the operating member reaches its operated position in the event that a closing operation rice is attempted with the mechanism in dition.

It is still another object of the invention to provide an improved electric switch comprising separable contacts and a control arm therefor, the control arm being adapted in cooperation with the above-described operating mechanism to actuate the contacts for deenergizing the electroresponsive means, wherein there is negligible tendency for the contacts to separate prematurely due to the shock of the operating member attaining its operated position during a normal closing operation.

A further object is the provision of an improved circuit breaker operating mechanisms having inertia actuated, gravity resetting means responsive to the opening velocity of the switch member for preventing appreciable rebound of the switch member from its open circuit position.

The operating mechanism described generally above may comprise a toggle having one end connected to the switch member of the circuit breaker and having its other end supported by a guide member which is disposed for movement from a latched position, where it is releasably held by suitable latch means, to an unlatched position. An overcenter spring interconecting the operating member and the toggle is eiective in response to movement of the operating member to its operated position with the guide member in its latched position to produce snapaction switch closing movement of the toggle, and the same spring is also effective in response to guide releasing operating by the latch means with the operating member in its operated position to drive the guide member to its unlatched position and produce switch opening movement of the toggle.

It is another object of the present invention to provide an improved operating mechanism of this type having means for obtaining a substantially uniform rate of energy release by the overcenter spring throughout the opening operation, whereby the switch member moves smoothly to its open circuit position from which its rebound is resisted by a relatively high force gradient exerted by the spring.

In carrying out my invention in one form, I provide a circuit interrupter including a movable switch member, an operating mechanism connected to the switch member and a movable operating member. The operating mechanism includes a guide member disposed to be releasably restrained in a latched position by suitable latching means and a spring connected to the operating member, the spring being arranged to release stored energy for imparting quick-action switch closing movement to the mechaniSm in response to movement of the operating member from a reset position to an operated position with the guide member in its latched position. The mechanism is arranged to undergo switch opening movement in response to subsequent release of the guide member by the latching means. Movement of the operating member is obtained by electroresponsive means, such as a solenoid and cooperating armature. I provide means responsive to the switch closing movement of the mechanism for deenergizing the electroresponsive means, the deenergizing means also being responsive to the switch opening movement of the mechanism thereby preventing the initiation of a subsequent closing operation until the operating mechanism is being reset by the return of the guide member to its latched position.

In one aspect of my invention, the aforesaid deenergizing means comprises an electric switch having a shaft supported by a base member which is subject to mechanical shock when the operating member of the circuit interrupter attains its operated position. An assembly is pivotally supported by the shaft and includes an electric conan unlatched contact normally disposed in engagement with a cooperating electric contact mounted on the base, the contacts being electrically connected in series relationship in the energizing circuit of the electro-responsive means. The assembly also includes a control arm disposed in cooperation with the operating mechanism for actuating the movable contact to a disengaged position. yI distribuite the total mass of the assembly so that its center of gravity lies approximately in the plane of the principal vibratory motion of the axis of the shaft with the movable contact in its engaged position, whereby the tendency for the assembly to move pivotally on the shaft upon the occurrence of the aforesaid mechanical shock is minimized.

In another aspect of my invention, i provide means for preventing appreciable rebound of the circuit interrupter switch member from its Vopen circuit position upon the completion of circuit opening movement thereof. This rebound preventing means comprises an elongated member pivotally connected to the switch member and means for guiding the elongated member so that it travels with e'ssentialy translational motion from first to second positlons in response to movement of the switch member from closed to open positions. I distribute the mass of the elongated member with its center of gravity located so that the kinetic energy of this member at the moment it reaches its second position will cause rotation of the 'member into interlocking engagement with a iixedly disposed rigid member which prevents movement of the elongated member directly toward its first position, thereby preventing appreciable rebound of the switch member, and so that the force of gravity action on the elongated member returns it to its second position when the aforesaid kinetic energy has been dissipated.

In still another aspect -of my invention, the circuit `interrupter operating mechanism comprises the aforesaid guide member, a toggle having one end connected to sw1tch member and its other end connected to the guide member, and an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its operated position with the guide member in its latched position to produce snap-action switch closing movement of the toggle. The overcenter spring is also effective in response to guiding releasing operation of the latching means to drive the guide member to an unlatched position and produce snap-actionV switch opening movement of the toggle. I provide means disposed in cooperation with the toggle and effective while the guide member is movmg toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation.

The invention will be better understood and its various objects and advantages will be more fully appreciated from the following description taken in conjunction with the accompanying drawings in which:

Fig. l is a side elevation of a circuit interrupter having an operating mechanism constructed in accordance with a preferred embodiment of the invention, the circuit interrupter being shown in its closed circuit position;

Fig. 2 is a fragmentary side elevation of the circuit interrupter of Fig. l showing the operating mechanism intermediate its closed and tripped-open positions during the opening operation of the interrupter;

Fig. 3 is a simplified side elevation of the circuit interrupter of Fig. l with the operating mechanism and the switch member of the interrupter being shown in trippedopen positions;

Fig. 3a is an enlarged fragmentary side view of the operating mechanism constructed in accordance with the preferred embodiment of my invention, the mechanism being shown both in its closed position (solid lines) and its tripped-open position (broken lines).

Fig. 4 is a partial side elevation of the circuit interrupter of Fig. l showing the operating mechanism in its open-reset position; i

Fig. 5 is an enlarged side view of the anti-rebound member of the operating mechanism showing this member in 'three different positions;

Fig. 6 is a diagrammatic representation of the energizing circuit for the closing solenoid;

Fig. 'I is a side elevation of the operating mechanism shown intermediate its open-reset and closed positions just prior to snap-action switch closing movement thereof;

Fig. S is a fragmentary side elevation of the circuit interrupter of Fig. l showing the operating mechanism during a trip-free operation which results when a closing operation is attempted with the mechanism unlatched;

Fig. 9 is an enlarged side elevation partly in section, of the electric switch shown in Figs. 1 4 and 8 forcentrolling the energization of the closing solenoid; and

Fig. l0 is a rear elevation of the electric switch of Fig. 9.

Referring now to Fig. l, I have shown an electric circuit breaker or interrupter comprising a frame member 11 supportingv a base member l2 of electric insulating material, a relatively stationary Contact or switch member l13 mounted on the base, a bracket i4 mounted on the base in spaced relation to the stationary contact member, a movable contact or switch member l5 pivotally supported by bracket 14 and disposed in cooperative relationship with the stationary switch member i3, and actuating means such as a crossbar i6 coupled to the movable switch member 15 for moving this member into and out of circuit-making engagement with the stationary switch member 13. Movement of the switch member 15 into and out of engagement with the member 13 closes and opens, respectively, an electric circuit represented by conductors 17 and 18. The

components

13, 14 and 15 comprise the Contact structure of one pole unit of an alternating or direct current circuit interrupter, and other pole units substantially identical to that shown could be mounted on the frame member il for gang operation by the common crossbar 16. The particular contact structure that has been snown in the drawings for the purpose of illustrating a preferred embodiment of the present invention is the subject matter of my cepending patent application S.N. 764,642 filed on October l, 1958, and assigned to the assignee of the present invention.

Movement of the switch member l5 between its ciosed circuit position (Fig. l) and its open circuit position (Fig. 3) is controlled by an operating mechanism whichV is connected to the switch member by means of an elongated connecting member 19 pinned to a link Ztl which in turn is firmly affixed to the crossbar 16. The operating mechanism comprises a plurality `of interconnected movable members one of which is a guide member 2l pivotally mounted on the frame member ll by means of a rod 22 fixedly supported thereby. The remaining members constitute a force-transmitting linkage mechanism 23 pivotally fastened by a pin 24 to the connecting member 19 and hence to the movable switch member l5. The pin 24 is supported for movement along a predeterminedarcuate path by an output crank 25 of the mechanism which is pivotally mounted on the frame member l1 at 26. The various illustrated parts of the operating mechanism, with the exception of the guide member 2i., preferably are provided in identical pairs so that the entire mechanism is symmetrical with respect to a vertical plane parallel to the plane of the drawings, with the guide member 21 being disposed in the plane of symmetry. The output crank 25 actually is a U-shaped member the two identical, spaced-apart upstanding parts of which are rigidly interconnected by a transverse part 25a.

The operating mechanism also includes at least one helical tension spring 27 arranged to release stored euergy to the mechanism for imparting quick-action switch closing and opening movement thereto. ccumulation of energy in the spring 27 is controlled by a movable operating member 28 which is pivotally mounted on the frame member 11 by means of the rod 22 afxed thereto. The operating member 28 preferably comprises two identical upstanding parts, only the far one being shown rigidly interconnected `by a pair of transverse sections 28a and 28b. The spring 27 interconnects the operating mechanism and a laterally extending pin 29 carried by the operating member 28.

The operating member 28 is disposed for pivotal movement between two different angular positions at opposite ends of its normal range of movement: a first or reset position shown in Fig. 4, and a second or operated position shown in Fig. 1. While moving to its second or operated position with the operating mechanism in a releasably latched condition (the latching means is described in detail hereinafter), the operating member will stress or charge the spring 27 and will effect release of energy thus stored in the spring for producing switch closing movement of the mechanism. In order to obtain this movement of the operating member 28, suitable electro-responsive means such as the solenoid 30 and cooperating armature 31 shown in Figs. 1 and 4 may be employed, or the operating member may be coupled to a suitably disposed manually operable handle, not shown.

In the illustrated embodiment of the invention, the operating mechanism includes a toggle comprising two

links

33 and 34 pivotally joined by a pin 35 which forms the knee of the toggle. (Actually, as has been pointed out hereinbefore, the

links

33 and 34 are provided in identical pairs, and the near one of the links 34 is omitted in the drawings for the sake of clarity.) The spring 27 functions as an overcenter spring, and one end of the spring is connected to the pin or toggle knee 35. One end of the toggle, specifically the right-hand end of the link 34 as viewed in the drawings, is connected to the pin 24 and hence to ythe switch member 15 for moving the switch member betwen its open and closed circuit positions. The other end of the toggle, specically the left-hand end of link 33, is supported by a pin 36 for movement between two different positions.

The pin 36 is connected to the guide member 21. As the guide member moves pivotally between predetermined latched and unlatched positions, the pin 36 is carried along a predetermined arcuate path 36p (Fig. l) with respect to the axis of the supporting rod 22. In Figs. 1 and 4 the guide member and lever 21 is shown in its latched position where it is releasably restrained by a latch identified generally by the reference number 37.

In order to close the circuit interrupter, the operating mechanism is arranged to -move the switch member 15 from its open circuit position to its closed circuit position with quick and positive action. This is accomplished by moving the operating member 2S from its first or reset position (Fig. 4) toward its second or operated position (Fig. l) in response to which the overcenter spring 27 is stretched or charged and moves over center with respect to the toggle link 33. The spring force being exerted on the toggle knee 35 will now produce in toggle link 33 a counter clockwise torque tending to straighten the toggle from its initially collapsed condition shown in Fig. 4. Upon release of energy stored in the spring, the toggle knee is pulled upward and the toggle undergoes snapaction switch closing movement which rotates the output crank 25 clockwise and drives the switch member 15 to its closed position.

The closed position of the operating mechanism, as can be seen in Fig. 1, is determined by the engagement of a pin 3S protruding laterally from toggle link 33 with an interfering stop surface 39 of the guide member 21, the guide member at this time being firmly held in its latched position by the latch 37. Suitable stop and blocking means, to be described hereinafter, are respectively provided for definitely determining the second position of the operating member 28 and for preventing the return of the operating member to its rst position as long as the switch member 15 is closed. As is evident in Fig. 1,

the second postion of the operating member 28 is so located in relation to the toggle after undergoing switch closing movement thereof that the line of action of the overcenter spring force intersects the path 36p to be followed by the pin 36 during subsequent movement of the guide member 21 to its unlatched position. In the closed position of the operating mechanism there is still a substantial amount of energy remaining in the overcenter spring 27, since not all of the stored energy was given up by this spring while effecting the above-described closing operation.

As is clearly shown in Fig. 1, the overcenter spring 27 exerts a force on the guide member 21, by way of toggle link 33 and the

pins

36 and 38, tending to drive this member in a clockwise direction from its latched position. It is the function of the latch 37 to prevent such movement by the guide member until a circuit opening operation of the interrupter is desired. The latch comprises a transversely extending trip shaft 4t) supported by the frame member 11 for rotary movement between a normal position shown in l and 4 and a trip position shown in Figs. 2 and 3. A radially protruding portion or prop 41 of the trip shaft 4% cooperates with an intermediate latch member or catch 42 for releasably restraining the guide member 21 in its latched position with the trip shaft in its normal position.

The latch member 42 is pivotally mounted intermediate its ends on .a transverse rod 43 which is supported by the frame 11. On one side of the rod 43 this member is provided with a stud 44 disposed in self-releasing engagement with the heel of an integral leg 45 of the guide member 21. With the trip shaft 4t) in its normal position, the stud 44 of the intermediate latch member 42 is lirmly held in engagement with leg 45 of the guide member, thereby maintaining the guide member in its latched position, by the prop 41 which abuts a roller 46 carried by the latch member on the other side of rod 43. The latch member 42 preferably comprises two similar parts (only the near one being shown) that are firmly joined by the stud 44 and the axle of the roller 46. A tension spring 47 is provided for biasing the trip shaft 40 in a clockwise direction to its normal position and for biasing the intermediate latch member or catch 42 in a clockwise direcv tion into self-releasing engagement with the guide member 21.

The intermediate latch member 42 with its roller 46 and the prop 41 are constructed and arranged so that the resultant force of action and reaction therebetween is directed normal to the axis of rotation of the trip shaft 40. To accomplish this result in the illustrated embodiment of the invention, the prop surface 41a abutting the roller 46 is conformed to a circumferential section of a right cylinder whose axis is the axis of shaft 4G. Consequently, the line of action of the resultant force transmitted by the prop 41 to the trip shaft, in order to restrain the guide member 21 in its latched position against 'the force of overcenter spring 27, intersects the axis of the trip shaft 4@ and has no moment arm with respect thereto. This arrangement helps to eliminate accidental unlatching operation by the latch 37 upon the occurrence of any relatively sudden and severe mechanical shock to the circuit interruptor. The prop 41 is in compression and free of bending stresses, whereby any tendency to distort adversely the circumferential surface 41a is relieved.

In order to open the circuit interrupter, the operating mechanism is arranged to move the switch member 15 from its closed circuit position to its opened circuit position with quick and positive action in response to toggle releasing operation of the latching means. The opening operation is initiated by rotating the trip device 4t) in a counterclockwise direction from its normal position (Fig. 1) to its tripped position (Figs. 2 and 3). For this purpose any suitable means may be used, such as, for example the schematically illustrated manually operable trip bar 48. Longitudinal movement of the trip bar 48 t'o the right, as viewed in Fig. l1, 'causes 'anA adjustablelength terminal portion 49 of this bar to Strike and tilt 'a paddle member 56 which is rigidly aixed to the trip shaft 40. As a result, the trip shaft is rotated counterclockwise and 'the prop is pivoted from the roller 46 of intermediate latch member 42. The force necessary to accomplish this result is significantly less than the force being exerted at this time by the overcenter spring 27 because of the favorable force amplifying leverage system formed by the interengaging pivotally supported

members

50, 41, 42 and 21 of the latching means. n

The removal of prop 41 from abutting relationship with roller 46 enables the intermediate latch member 42 to move counterclockwise about rod 43 in accordance with the force applied at its stud 44 by the leg 45 of guide member 21, whereupon the guide member is no longer restrained in its latched position. The overcenter spring 27 is effective in response to this guide releasing operation of the latch 37 to drive the guide member to its unlatched position (Fig. 3) thereby enabling the operating mechanism to undergo switch opening movement. As the spring releases energy during the opening operation, the toggle knee 35 is pulled to the lett (as viewed in Fig. 1) and the pin 36 carried by the guide member moves upward along its arcuate path 36p. When the pin 36 has passed through the line of action of the overcenter spring 27 (the operating mechanism is shown at this instant in Fig. 2), the toggle collapses and undergoes snap-action switch opening movement. During this action the output crank 25 is rotated counterclockwise and the movable switch member 15 is driven to its open circuit position.

The operating mechanism is shown in a collapsed, tripped-open condition in Fig. 3. As can be seen in this iigure, the open position of the switch member 15 and the corresponding position of the mechanism output crank 25 are determined by the engagement of a bushing 52 located on pin 24 with a concave stop surface 53 of the frame member 1l. The guide member 21 is here in its unlatched position which is determined by the engagement of a shoulder 54 of the guide member with suitable stop means such as the illustrated rod 55. The rod 55 is rigidly aixed to the frame 11 and blocks further clockwise movement of the guide member 21 about its pivot 22. Since one end of the toggle is counected to the pin 24 and the opposite end is connected through pin 36 to the guide member 21, the position of the toggle knee 35 at this time is necessarily Xed. For reasons which will be explained hereinafter, the operating mechanism is only momentarily in the position in which it is shown in Fig. 3.

During the above-described opening operation, the toggle knee 35 is forced to follow a relatively linear path from its position shown in Fig. l to its position shown in Fig. 3. This is accomplished by providing suitable cammiug means controlled by movement of the guide member 21 and disposed in cooperation with the toggle. Preferably the cammiug means comprises a concave cammiug surface 56 of the guide member 21 which engages a roller 57 connected to the toggle link 34 while the guide member is moving toward its unlatched position. As a result, the movement of the toggle is controlled in a manner to obtain a substantially uniform Trate of energy release by the overcenter spring 27 throughout the opening operation, and the spring will manifest a relatively high force gradient in resisting rebound of the movable switch member 15 from its open circuit position.

This rea ure oi can be better understood by referring to Fig. 3a and the following explanation. In Fig. 3a the toggle links and the guide member in their respective closed`positions (as in Fig. l) are shown by solid lines and identied by the reference numbers used hereinbefore The "same members after 'being moved to their predetermined tripped-open positions (as in Fig. 3) have been shown in Fig. 3a by dot-dash lines and identified by the same reference numbers primed. The pin 29 to which one end of the overcenter tension spring 27 is connected is shownin section at a stationary point, because the operating member 23 does not move from its second or operated position while the operating mechanism is undergoing switch opening movement. In the interest of clarity neither the overcenter spring nor the operating member have been shown in Fig. 3a.

During the opening operation, the left end of the toggle connected to pin 36 is guided along the predetermined arcuate path 36p, and the right or output end of the toggle connected to pin 24 is moved along the arcuate path 24p. The path 24p is determined by the output crank (not shown in Fig. 3a) which is pivotally supported at 26. Movement of pin 24 along path 24p to its open position 24' produces the opening movement of switch member 15 to which it is positively connected. The path 35p followed by the toggle knee 35 is determined by the cammiug action of the interengaging cammiug surface 56, which is integrally associated with the guide member 21, and roller 57, which is rotatably supported by toggle link 34 intermediate its ends. The cammiug surface 56 is contoured and the ro-ller 57' is disposed so that the cammiug action therebetween directs the toggle knee along the relatively linear path 35p during the opening operation.

The overcenter spring is connected between pin 29 and the toggle knee 35. By controlling the switch opening movement of the toggle in the manner described above, the energy given up by the spring per unit of distance moved by the pin 24, and consequently per unit ot angular movement traversed by the switch member t5 while opening, is substantially constant throughout the opening operation. That this action results iu a substantially uniform rate of energy release by the spring is demonstrated lin Fig. 3a where point A on path 35p indicates the position of the toggle knee 35 when the pin 36 is passing through the line of action of the spring force, at which point snap-action opening begins. See also Fig. 2. At this moment the pin 24 will be at point l on path 24p. With the toggle knee at A, the spring approximately 62 percent discharged (i.e., the spring has shortened approximately 62 percent of the total amount by which its length will change while effecting the switch opening movement of the mechanism), and at vthe same moment the movable switch member will be approximately 67 percent o-pen. Thus slightly over onethird of the energy originally available remains in the spring to etect the last one-third of the switch opening operation.

rthis feature of my invention is important because it ensures maximum available opening action of the circuit interrupter switch member i5 throughout Ithe opening operation. Without this feature, the toggle knee 35, while traveling to its iixed position 35, would follow the Z-step path identified in Fig. 3a by the reference number 53. Point D on the path 5S indicates the position in which the toggle knee would be located at the moment when snap-action opening begins, and at the same moment ythe pin 24 would be at a point E. lt can be observed that at this moment the switch member is only halt-way open while the overcenter spring is already nearly 75 percent discharged. By controlling the toggle movement in accordance with my invention, the movable switch member l5 is moved smoothly to its open circuit position without any point of hesitation, and the tendency for the switch member to rebound from its open position is resisted by a orce gradient appreciably greater than that obtainable i the toggle knee were permitted to follow path 58.

When the overcenter spring 27 alone is imparting switch opening movement to the above-described operating mechanism, rebound of the movable switch member 15 from its open circuit position upon completion of its circuit opening movement presents no special problem. However, the arrangement of the contact structure of the circuit interrupter is such that when current of shortcircuit magnitudes is interrupted, strong magnetic forces augmenting the spring force will drive the switch member 1S to its open position with exceptionally high speed. In accordance with my invention, appreciable rebound of the switch member under these conditions is prevented by inertia actuated means which will now be described in detail.

The inertia actuated means referred to above comprises an elongated anti-rebound member 59 pivotally connected near its upper end, as viewed in Figs. 1-4, to the pin 24 and hence, by Way of the connecting member 19, link 20 and crossbar 16, to the movable switch member 15. Member 59 preferably comprises two identical parts (the side elevation of only the far one being shown in Figs. l-S) which are rigidly interconnected by a transverse part 59a. The member 59 is pivotally movable in a Vertical plane about the axis of pin 24, and this axis is moved along a predetermined arcuate path in the vertical plane during circuit opening movement of the switch member 15. A lower edge 60 of the anti-rebound member 59 slidably engages the upper surface of the transverse rod 43, whereby the member 59 is supported in a predetermined inclined position, in which it is shown in Fig. l, whenever the switch member 15 is in its closed circuit position.

In response to movement of the switch member to its open circuit position, the anti-rebound member 59 is moved to a predetermined second position (shown in Fig. 3) substantially parallel to its first inclined position. During this movement the member 59 is guided by the rod 43. The edge 6@ of member 59 is so configured in relation to the rod 43 that member 59 travels with essentially translational motion to its second position even through the axis of pin 24, to which it is pivotally connected, is moving through an arcuate path. A rigid stop member 6i is tixedly disposed on the frame member 11 in spaced relation to a cooperating hook-like portion 62 of the anti-rebound member 59 protruding laterally from the distal end thereof. The member 59 is free to rotate in a clockwise direction from its second position, and upon undergoing such rotation the portion 62 of member 59 engages in interlocking relation the stop member 61 thereby preventing movement of the member 59 directly toward its rst position (Fig. 1). This prevents appreciable rebound of the switch member 15 towards its closed circuit position.

The mass of the anti-rebound member 59 is distributed so that its center of gravity is located at the point indicated by the reference letter C in Fig. 5. Fig. is an enlarged view of the member 59 showing it in three diferent positions. With the circuit interrupter closed this member will be in its first position which is shown in Fig. 5 by a broken line identified as 59 with the interrupter opened the anti-rebound member is in its second position shown by solid line 5d, and its position after being rotated clockwise into interlocking engagement with the fixed member 61 is shown by the dot-dash line identitied by the reference character 59". The force of inertia erective at the conclusion of the translation movement of the anti-rebound member is indicated by the vector which is tangent to the arcuate path G along which the center of gravity travels while moving from its first position C' to C.

It can be observed in Fig. 5 that the force establishes a clockwise torque or moment in the anti-rebound member 59 tending to rotate this member about its pivotal axis P to its position 59'?. This torque is opposed by a counterclockwise torque established by the force of gravity which has been effective to hold the edge 60 of member 59 against the guiding rod 43. The inertial force is relatively large since the opening speed of the movable switch member is very high and the moment arm of this force is relatively long. Consequently, the inertial torque will easily overcome the gravitational torque and produce clockwise rotation of member 59. A yieldable buffer or cushion 63 is provided for the purpose of elastically stopping the clockwise rotation of the anti-rebound member. With the member in its rotated position 59, its center of gravity is at C and the gravitational force acting thereon returns the member to its second or static position.

The operation of the rebound preventing means will now be summarized with reference to Fig. 5 during a circuit opening operation, the pin 24 moves quickly along the arcuate path 24p to its solid-line position where it is abruptly stopped due to the engagement of bushing 52 with stop surface 53 (see Fig. 3). Simultaneously the anti-rebound member 59 is guided translationally to its solid-line position. When member 59 reaches this position, its kinetic energy will impart clockwise rotation thereto and its hook-like portion 62 begins swinging in the direction of member 61. At the same moment the pin 24, and hen-ce the movable switch member of the circuit interrupter, will begin rebounding, and therefore the axis or rotation of the anti-rebound member 59 will start mov-ing back along path 24p. The relative masses and shapes of the various moving parts of the illustrated structure are selected so that the time required for the portion 62 to move into engagement with the fixed member 61 approximately coincides with the time that elapses while the axis of rotation is rebounding to the point designated P. Further rebounding movement of the mechanism and the switch member is abruptly halted by the interlocking engagement of 61 and 62. When the kinetic energy of the member 59 has been dissipated, the force of gravity will automatically return this member to its static position.

The above-described action requires no springs or other extrinsic biasing means. By guiding the antirebound member for translation motion, very little space is needed in order to carry out the operation. Optimum coordination between the movement of the anti-rebound member and the rebound of the switch member is obtained in accordance with my invention, since the energy availa'ble for propelling the former in a clockwise direction into rebound-preventing engagement with the fixed member 61 is directly responsive to the opening velocity of the latter. In other words, the greater the opening speed of the switch member and severity of its rebound tendency, the more rapid is the clockwise rotation of the member 59 which prevents appreciable rebound.

In order to successfully carry out a subsequent circuit interrupter closing operation it is necessary to ensure that the anti-rebound member 59 is not rotated clockwise into interlocking engagement with the Xed member 61 due to mechanical shock. For this purpose I provide a protrusion 64 on the lower edge of the toggle link 34 which is disposed in the position indicated in Figs. 4 and 5 when the operating mechanism is in its open-reset position. In this position the protrusion 64 is located in the path followed by part 59a of the member 59 during clockwise rotation thereof. Consequently, should the antirebound member 59 bounce oft the rod 43 during the initial phase of the closing movement of the switch member l5, the protrusion 64 will block the member 59 before its hook-like portion 62 can reach the fixed member 61. With this arrangement the inertia actuated, gravity reset anti-rebound member 59 cannot impede normal closing or" the circuit interrupter.

The circuit interrupter operating mechanism, in the illustrated embodiment of the invention, is automatically moved by the overcenter tension spring 27 from its stripped-open position of Fig. 3 to its open-reset position vcan be arranged diterently so that movement of an operating handle is required to accomplish the resetting operation. Regardless of whether it is eiected automatically by thespring 27 or manually by other means, the resetting operation is basically the same; the operating member 28 is returned to its rst or reset position, the guide member 2l is simultaneously driven to its latched position, and the toggle is moved in its collapsed condi- Ition to the position in which it is shown in Fig. 4.

With the operating mechanism in its tripped-open position, as can be seen in Fig. 3, the overcenter spring 27 is exerting a force `on the operating member 23 tending to move this pivotally mounted member in a counterclockwise direction toward its first or reset position. Counterclockwise movement of the operating member carries pin 29 along a predetermined arcuate path 29p shown in Fig. 4. An arm 65 of the guide member 2l is disposed, with the guide member in its unlatched position, immediately below the laterally extending pin 29. While the operating member is being moved from its irst to its second positions, the pin 29 engages the upper surface of `arm v 65 and drives the guide member 2i in a counterclockwise direction about its pivot 22 to its latched position. While moving toward its latched position, the guide member, being pinned at 36 to the toggle link 33, impels the toggle to its open-reset position shown in Fig. 4. in attaining this position, the toggle knee 35 has iollowed a path 351' which progressively converges with the arcuate path 29p of pin 29. Therefore the over-center tension spring 27, which is connected between pin 29 and toggle knee 35, progressively shortens during the resetting operation and releases energy for returning the 'operating member 2S to its first position and for driving the guide member Z1 to its latched position.

During the resetting operation of the mechanism, the latch 37 is also reset thereby releasably restraining the guide member 2l in its latched position. When the guide member is in its unlatched position (Fig. 3), and during the initial movement of this member toward its latched position, the intermediate latch member 42 is held in a tilted position against the force of its bias spring 47 `by vthe guide member leg whose lower surface Slidably engages a cooperating extension 66 of the member 42. The ieg 45 slides across the top of stud 44 as the guide member approaches its latched position and nally passes beyond this stud, whereupon the intermediate member 42 is tree to pivot clockwise on rod 43 in accordance with its bias and the stud 44 moves into self-releasing engagement with the heel of leg 45. This enables the trip shaft 4@ to return to its normal position, and the prop 4i moves into its abutting disposition with respect to the roller 46 of latch member 42. See Fig. 4. When the operating member 2S is subsequently moved toward its second or operated position, member 42 will tilt slightly into engagement with prop 41 and the latch 37 is again effective to restrain the guide member 21 in its latched position.

The above-described resetting operations cannot take place until the movable switch member 15 of the circuit interrupter has moved from its closed circuit position vto its open circuit position. This is due to the provision of blocking means for positively preventing movement of `the operating member 28 from its second or operated position to its iirst or reset position whenever the switch `member yis closed. Since the operating member is blocked -in its second position with the switch member closed, the only way the .circuit interrupter can be opened is by i2 actuating the latching means in consequence of which the operating member is permitted to return to `its iirst position.

The blocking means preferablyv comprises a pair of cooperating blocking

elements

67 and 68 associated with ltie operating member 28 and the .mechanism output crank 25, respectively. As can be seen in Fig. 1, the blocking element 67 is an integral limb of the operating member .having a blunt end and generally curved edges ldisposed for movement along a predetermined arcuate path in accordance with the pivotal movement of the operating member 28 between its iirst `and second positions. The cooperating element 63 comprises la lug extending transversely from a projection of the output crank for movement about pivot 26 in response to circuit Vopening and closing movement of the switch member 15. ln other words, the blocking element 68 is actuated by movement of pin 24 which physically interconnects the output end of the 'toggle and the movable switch member 15.

By moving the operating member 28 from its rst position shown in Fig. 4 to its second position shown'in '.Fig. l, a snap-action switch closing operation of the .mechanism is effected. The blocking element 68 is accordingly moved into the predetermined path of movenent of the blocking element 67 where, as best seen in Fig. 1, it interferes with the blunt end `ot element 67 and positively 'blocks the operating member 28 in its second position. When later the ylatching means is operated to release the toggle, lthe mechanism undergoes switch opening movement during which the element 66 is moved out of the aforesaid predetermined path to unblock the operating member 26, as shown in Fig. 3. Only now can a resetting operation be undertaken and the operating member moved to its iirst position (Fig. 4).

Thus, the blocking means which became effectiveduring the closing operation to releasably restrain the operating member 2S in its second position, is moved only in response to a subsequent opening operation to free the operating member for return to its iirst position. The blocking means is arranged so that movement of the operating member 2S toward its rst position is permitted only after the snap-action switch opening movement of the toggle has been initiated and the movable switch member i5 is substantially fully opened, whereby in the illustrated embodiment of the invention the automatic resetting operation cannot begin until after the opening operatic-n is practically completed.

With `the operating mechanism in `its open-reset position, the circuit .interrupter can be closed by energizing nected .in-series circuit relationship to a suitable source of control power 73 in the manner shown diagrammatically in Fig. 6. Closing the control switch enables current to flow through the solenoid coil, and the resulting force of Vmagnetic attraction causes the armature or plunger 3i to move upwardly from the position in which it is shown in Fig. 4. vThis drives the operating member 2S toward its second position in response to which energy Vis accumulated in the overcenter spring 27 and a switch closing force is exerted on the toggle.

The actual snap-,action switch closing movement of the toggle cannot take place before the operating member 23 reaches a predetermined point near its second position Vsuch as is shown in Fig. 7. This is due to the provision operating member is `moved passed the aforesaid predetermined point, whereupon the switch member is ire- 13 leased and the toggle is able to undergo switch closing movement in accordance with the force being exerted by the overcenter spring.

The predetermined point at which the blocking means becomes ineifective and energy stored in the spring is first released for imparting switch closing movement to the mechanism is selected in the illustrated embodiment of my invention, for example, so that the operating member must be moved through approximately 97 percent of its total range of movement in order to reach this point. This ensures that the overcenter spring 27 will be substantially fully charged with the maximum amount of energy being stored therein before any of its energy is released. Thus the closing and subsequent opening and resetting operations of the circuit interrupter will be unaffected in the event control power should fail while the movable switch member is closing. By providing a. definite, fixed release point, the blocking means also ensures that a substantially constant amount of closing energy is always available each time the circuit interrupter is closed and regardless of the speed with which the operating member 28 is moved to its second position.

The blocking means preferably comprises the same pair of cooperating blocking

element

67 and 68 described hereinbefore. The blocking element 68, which is associated with the output end of the toggle, is disposed for movement along a predetermined arcuate path about pivot 26 during closing movement of the switch member 15. With the operating member 28 in its first angular position and during most of the movement of this member toward its second position, as clearly indicated in Figs. 4 and 7, the blocking element 67 is disposed in this predetermined path and the element 68 is positively blocked by the lower edge thereof, whereby appreciable switch closing movement of the toggle is prevented.

When the operating member approaches its second position, it passes through the position in which it is shown in Fig. 7 (line 29p in Fig. 7 representing the path being followed by the laterally extending pin 29 carried by the operating member), and it will be observed that the tension spring 27 has moved overcenter with respect to the toggle link 33 at this point. As the operating member proceeds beyond this point, it causes the blunt end of element 67 to move beyond element 68 which will now be able to travel freely along its predetermined path. In this manner the blocking means consistently operates near the end of the movement of the operating member toward its second position to free the toggle and to effect release of energy stored in the spring 27 for producing switch closing movement of the operating mechanism, whereupon the closing operation is completed.

As the circuit interrupter operating mechanism is undergoing switch closing movement, the element 68 moves into its blocking position (Fig. l) wherein it releasably restrains the operating member 28 in its second position. It is important that the electromagnetic means which has moved the operating member to its second position remain energized until this blocking action has taken eiect, thereby maintaining the operating member in its second position while the switch closing movement of the mechanism is getting underway. In order to accomplish this result, the cutoff switch 72, which controls the energization of the solenoid 30, is arranged to be actuated in response to the switch closing movement of the mechanism. This will ensure that the operating member 28 is blocked in its second position and that the spring energy has been released for imparting irreversible switch closing movement to the operating mechanism before the solenoid is deenergized.

The cutoff switch 72, as is shown in Figs. l-4, comprises a resilient switch arm 74 supporting the electric contact 70 at one end and pivotally connected at its other end to a transverse shaft 75. The shaft 7S is suspended between two spaced-apart supporting elements 76 (only the near one being shown) fastened to a base member 77, and the cooperating electric contact 71 is mounted on a bracket 78 also fastened to the base member 77. The base member 77 is located above the operating mechanism of the circuit interrupter where it is aflixed to the frame 11. A broad cantilever control arm 79 is yieldably coupled to the switch arm 74 and depends from the cutoff switch in cooperation with the operating mechanism for actuating the separable contacts and 71. Suitable spring means is provided for biasing the interconnected switch and control arms 74 and 79 in a counterclockwise direction about the shaft to predetermined normal positions wherein the contact 70 is maintained in an engaged position with respect to contact 71, as can be seen in Fig. 4.

The control arm 79 of the cutoff switch 72 is located so as to be mechanically independent of the armature 31 of the electromagnetic means. In order that switch 72 may be actuated in response to switch closing movement of the operating mechanism, its control arm is disposed for engagement by an upwardly extending appendage 33a of the toggle link 33. The final stage of a closing operation involves the straightening of the toggle with snapaction, and the toggle link 33 is abruptly pivoted counterclockwise on pin 36 from the position shown in Fig. 7 to the position shown in Fig. l. As a result, appendage 33a of link 33 engages the control arm 79 and tilts this arm in a clockwise direction about shaft 7S to an actuated position, thereby causing separation of the cooperating contacts 70 and 71. See Fig. l. The contact 70 has been moved to a disengaged position thereby opening the energizing circuit for the solenoid 30 and deenergizing the electromagnetic means. The operating member 28, which was being upheld in its second position by the armature 31, is now releasably restrained in this position by the

abutting blocking elements

67 and 68, and the armature 31 cannot return to its original position shown in Fig. 4.

As long as the circuit interrupter is closed, the control arm 79 of the cutoff switch is held in its actuated position, thereby preventing reenergization of the electromagnetic means, by the operating mechanism acting through link 33. The control arm is also disposed for engagement by a protrusion 80 of the guide member 21 in response to switch opening movement of the operating mechanism, whereby control arm 79 is maintained in its actuated position, and energization of the solenoid 30 is prevented, with the mechanism in its tripped-open position (Fig. 3). Upon operation of the latch 37 with the circuit interrupter closed, the guide member 21 is driven in a clockwise direction about pivot 22 to its unlatched position and protrusion 80` moves into engagement with control arm 79. At the same time the toggle is collapsing and appendage 33a of toggle link 33 rides along the curved underside of arm 79 while holding this arm in its actuated position.

The operating mechanism is arranged so that during the initial portion of its switch opening movement the appendage 33a of link 33 is maintaining the control arm 79 in its actuated position, while during the remaining portion of this movement the protrusion St) of guide member 21 will prevent the control arm from returning to its normal position, whereby the cooperating electric contacts 74) and 71 are caused to be separated throughout the opening operation. This is best illustrated in Fig. 2 which shows the mechanism at a point during its opening operation where protrusion 80 is about to engage arm 79 before the appendage 33a disengages it.

The cutoff switch 72 will not reset to permit subsequent energization of the solenoid 30 until a resetting operation of the mechanism is underway, as indicated by counterclockwise movement of the guide member 21 toward its latched position. This ensures that before the solenoid can again be energized the movable switch member 1.5 is fully open and the condition of the operating `mechanism and the armature 31 will be proper for a normal closing operation. During the resetting operation, the protrusion Sti of the guide member 21 drops away from the control arm 79 thereby enabling the control and switch arms 79 and 74 to move to their normal positions in accordance with their bias, whereupon contact 7 ti engages contact 7i to set up the energizing circuit for the solenoid 3l) (Fig. 4).

If a circuit interrupter closing operation is attempted while the operating mechanism is unlatched, the separable contacts 79 and 71 of the cutoff switch 72 will be actuated, in accordance with my invention, before the operating member 28 reaches its second or operated position. As a result the solenoid 30 is deenergized before the armature 31 reaches the upper, fully attracted limit of its travel, thereby minimizing the heating of the solenoid coil and lessening the impact which occurs when the armature impels the substantially unloaded operating member 2S to its second position under these conditions. Such a trip-free operation of the mechanism is illustrated in Fig. 8.

In Fig. 8, the armature of the electromagnetic means has driven pin 29 of the operating member 28 upward along its predetermined arcuate path 29p to the position shown, and the position of the operating member is now intermediate its iirst position (Fig. 4) and its second position (Fig. l). The latch 37 has been operated, either before or at any time during movement of the operating member 28 toward its second position, to release the guide member 21. This has enabled the overcenter spring 27 to drive the guide member in a clockwise direction toward its unlatched position. The guide member moves conterrninously with the operating member 28 because both of these members are pivotally supported on the same rod 22 and the upper surface of the arm 65 of member 21 engages the pin 29 of member 28. Consequently, as the operating member 28 is moved toward its second position, the toggle moves in a collapsed condition, the overcenter spring 27 cannot accumulate closing and tripping energy, and closing movement of the circuit interrupter switch member is prevented.

While the guide member 21 is thus being moved toward its unlatched position, the priotusion 80 thereof engages the control arm 79 of the cutoff switch 72 thereby moving this arm to its actuated position, in which it is shown in Fig. 8, and deenergizing the electromagnetic means. It can be observed that actuation of the cutoff switch has been accomplished while the operating member 23 is still moving toward its second position, in contrast to a normal closing operation when the cutoi switch is not actuated until after the operating member 2.3 has reached its second position. After deenergizati'on of the electromagnetic means at the conclusion of a tripfree operation, the various parts of the circuit interrupter will automatically reset in the manner already described.

During a normal closing operation, as has been explained in detail hereinbeiore'the armature 31 of the electromagnetic means drives the operating member 28 to its second position in response to which the overcenter spring 27 imparts switch closing movement to the operating mechanism, and the cutoi switch72 is arranged to be actuated during the switch closingmovement of the mechanism for deenergizing the electromagnetic means. Since the base 77 of the cutoff switch is mounted on the frame member l of the circuit interrupter, it receives a relatively sudden and severe mechanical shock upon the operating member attaining its second position. The cooperative electric contacts 7i) and 71 of the cutoi switch must remain engaged when this shock occurs, because, as pointed out hereinbefore,V it vis important that the electromagnetic means remain energized to hold the operating member in its second position while switch closing movement of the mechanism is getting underway. Inaccordance withmy invention, the cutoi switch 72 is i6 designed'so that its actuation is not elected by shock, and premature separation ofthe contacts 70 and 71 is avoided. As viewed in the drawings, the armature or plunger 31 travels in a generally vertical direction while moving the operating member 28 toward its second or operated position, and the mechanical shock occasioned by the armature 3l and the operating member 2S being abruptly 'stopped in their positions shown in Fig. l will cause the frame member M to shake or vibrate vertically. The shaft 75 is supported by the base 77 of the cutoff switch 72 is so oriented that it vibrates laterally as a result of this shock, the principal vibratory motion of the axis of shaft 75 defining a generally vertical plane. This plane of lateral vibration is represented by the trace 81 in Fig. 9 which is an enlarged side elevation of the cuto switch.

in accordance with my invention, the total mass of the assembly pivotally supported by the shaft 75, i.e. the interconnected switch and control arms "i4 and 79, is distributed so that its center of gravity H lies approximately in the plane 81 when the arms are in their normal positions. See Fig. 9. In other words, although the arms 74 and 79 when in their normal positions are asymietrically disposed with respect to the plane 81, their respective masses are so kdistributed that the center of gravity of the physical system formed by their combination lies approximately in this plane of lateral vibration. Consequently, the parts of the pivotally movable assembly 74, 79 located on opposite sides of the plane 81 will be substantially equally accelerated from rest upon the occurrence of the aforesaid mechanical shock, and no appreciable net moment is established in this assembly, with respect to shaft 75, by the resulting inertial forces acting thereon. This minimizes any tendency on the part of the switch arm 74 to move pivotally about the axis of shaft 75 while the shaft is vibrating laterally, and the movable electric contact 70, which is located at the distal end of arm 74, will have negligible tendency to move relative to the cooperating contact 7l with which it engaged.

Additional details of the cutoff switch 72 have been shown in Figs. 9 and 10 and will now be described. The Vswitch arm 74. includes a block 7 4a of insulating material to which the resilient portion of the arm is suitably an.- chored. The block 74a is securely fastened by means of a bolt S2 or the like to the bight of a generally U- shaped metallic portion 74k of the armature, and the up'standing legs of 74h are pivotally connected to the shaft 75. The control arm 79 includes a generally flat portion' 79a and a pair of spaced-apart ears 79k having openings through which the shaft 75 passes. The flat portion 79a is clamped firmly but yieldably against the block 7 4a of the switch arm 7 4 by the action of the relatively stiff torsion spring S3 as best seen in Fig. l0. This spring applies pressure at two lugs $4 and S5, respectively associated with one leg of 7fzb and an ear 7917, so-as to urge the switch and control arms 74 and 79 in opposite directions about the shaft 75. The at portion 79a of arm 79 and the block 74a of arm 74 are thus held rmly together with the shaft 75 serving as a fulcrum for both arms, and the arms are pivotally movable as a unit.

The unit assembly comprising arms 7 4 and 79 is biased in a counterclockwise direction to its normal position, as viewed in Fig. 9, by another torsion spring 86 which is weaker than spring 83. One end of the spring 86 is xedly restrained and its other end acts through a lug 37 associated with the other leg of 74!) to establish in switch arm 74 a counterclockwise torque with respect to shaft 75. This biasing torque is transmitted to the control arm 79 by means of the spring 83. Upon actuation of the cutoi switch 72 in the manner described hereinbefore, the control arm 79 is moved in a clockwise directien to its actuated position. As a' result the switch arm 74 is carried in a clockwise direction against its bias until such movement is stopped by a lip 88 of 74h engaging an 17 abutting shelf 89 mounted on the base 77 of the switch (see Fig. 1). At this point, the spring 83 will yield to permit further clockwise movement of the control arm 79, thereby providing for overtravel by the control arm.

Actuation of the cutoff switch 72 causes the normally engaged contacts 70 and 71 thereof to separate. The relatively stationary contact 71 is preferably attached to a conductive leaf spring 71a mounted on the bracket 78, the leaf spring 71a being in a deliected state when the contact 70 is in its engaged position as shown in Fig. 9. This enables contact 71 to follow the contact 70 during the initial portion of the clockwise movement of the switch arm 74, thereby delaying separation of the contacts and contributing to the desired shock resistance of the structure.

Another electric contact 90 is provided on the resilient switch arm 74 for engaging a cooperating stationary electric contact 91 when the cutolf switch has been actuated. The contact 91 is connected to a conductive stud 92 disposed in an insulator 93 depending from the base 77. The

electric contacts

70, 71, 90 and 91 are connected by means of liexible conductors or the like to suitable terminals or connection posts (not shown) adapted for electrical connection to external circuits. As mentioned earlier, the separable contacts 70 and 71 are serially connected in the energizing circuit for the solenoid 30, and these contacts must be engaged, as they are with the circuit interrupter operating mechanism -in its open-reset position (Fig. 4), before the solenoid can be energized.

When energized, the solenoid 30 will produce a magnetic field. A magnetizable yoke 94 provides physical support for the solenoid and forms a part of the magnetic circuit for its held. The yoke 94 comprises a plurality of iron laminations stacked between a set of hangers 95, and the hangers 95, as can be seen in Figs. l and 4, are provided with mounting feet securely fastened by rivets or the like to the underside of a horizontal channel element 11a of the circuit interrupter frame member 11. Preferably the yoke is made in two separate parts, the bottom part including supporting elements 96 which are respectively fastened to the hangers 95 by bolts 97. This enables the hollow spool 98 on which the solenoid coil 99 is wound to be conveniently clamped between the two parts of the yoke 94 as indicated in the drawings.

The yoke 94 includes a pole piece (not shown) which extends into the solenoid spool 98 at its upper end. The width of tne pole piece is less than the corresponding distance between the spool sidewalls, whereby ample passage ways are provided on opposite sides of the pole piece, respectively, for a pair of generally longitudinally movable, spaced-apart elongated

metallic strips

103 and 104. The

strips

103 and 104 comprise part of the armature or plunger 31 which is disposed within the solenoid 30 for longitudinal movement under the influence of the force of magnetic attraction.

A laminated, magnetizable core piece 105 of the plunger 31 is sandwiched between the

strips

103 and 104, near their lower ends, where it is securely attached by means of recessed-head rivets or the like. The core piece 105 comprises another portion of the magnetic circuit for the magnetic iield produced by the soleno-id 30 when energized, and, in cooperation with the yoke 94, it is disposed for movement into the lower end of the solenoid spool 98 in accordance with the magnetic force exerted by the field. For this purpose the laminae comprising the bottom part of the yoke 94 are discontinued immediately beneath the opening through the spool 98, and the supporting elements 96 are appropriately bowed at 96a. The

strips

103 and 104 of the plunger 31 extend upwardly through the solenoid spool passing on opposite sides of the core piece of the yoke 94, and are rigidly joined at their upper ends to an armature extension 107 which in turn is positively connected by means of the pin 29 to the operating member 28 of the circuit interrupter operating mechanism.

Upon energization of the solenoid coil 99, the core piece of armature 31 is moved by the forcesof magnetic attraction in a generally longitudinal direction from a lower or normal position shown in Fig. 4 to an attracted position at the upper limit of its longitudinal movement, shown in Fig. 1. The magnetic force is transmitted by way of the armature extension 107 to the operating mechanism whose member 28 is thereby driven from its first or reset position to its second or operated position, and as a result the circuit interrupter is closed. The operating member 28 is stopped in its second position, beyond which it cannot be moved, by the abrupt interengagement within the solenoid 30 of the care piece of armature 31 and the pole piece of yoke 94 occurring when the armature attains its attracted position. This is the stop means for the operating member referred to hereinbefore. The force of gravity assists in returning the armature 31 to its normal position during the previously described resetting operation of the mechanism, and the normal position of the armature is determined by the interengagement of the bottom edge 107a of the armature extension 107 with the top of yoke 94.

Having described in detail the circuit interrupter structure illustrated in the drawings, its mode of operation will now be summarized. With the circuit interrupter switch member 15 in an open circuit position and the operating mechanism in its reset condition, as is shown in Fig. 4, the contacts 70 and 71 of the cutoff switch 72 are in engagement and a closing operation may be initiated by operating the external control switch 69 to energize the solenoid 30. The plunger 31 is raised from its normal position by the resulting force of magnetic attraction, and the operating member 28 is driven in a clockwise direction about its pivot 22 toward its operated position. This stretches the tension spring 27 which consequently accumulates closing, tripping and resetting energy. The spring is carried overcenter with respect to the toggle link 33 of the mechanism, and a closing force is exerted on the toggle.

During this portion of the closing operation the toggle is substantially immovable, and consequently the switch member 15 cannot be moved to its closed circuit position, because the toggle link 33 is being held stationary by the guide member 21 which is releasably restrained in its latched position by the latch 37, and the toggle link 34 is being held stationary by the blocking action of

elements

67 and 68 which prevent appreciable clockwise movement of the output crank 25 to which the link 34 is pinned. As the operating member 28 approaches its operated position, it reaches a point just beyond the position in which it is shown in Fig. 7 and the blocking element 67 is moved out of engagement with the element 68. The output crank 25 is now free to move clockwise about its pivot 26, and the spring 27 immediately releases stored energy as snap-action switch closing movement is imparted to the operating mechamsm.

Early during this switch closing movement of the mechanism, the blocking means 67, 68 becomes effective to prevent the return of the operating member 28 toward its reset position. The solenoid 30 will remain energized, thereby upholding the operating member in its operated position, until the separable contacts 70 and 71 of the cutoff switch are actuated by the control arm 79 upon engagement thereof by appendage 33a of the operating mechanism during the final stage of its switch closing movement. See Fig. 1.

To initiate an opening operation, the trip shaft 40 is rotated counterclockwise from its normal position thereby removing the prop 41 from roller 46. As a result, the latch 37 releases the guide member 21 which is forthwith driven in a clockwise direction about its pivot 22 by the action of the tension spring 27. This enables the spring to release opening energy, and the mechanism undergoes switch opening movement thereby pulling the i9 switch member to its open circuit position shown in Fig. 3. vAs the guide member ismoving to its unlatched position,'the toggle link33 moves throughthe centerline of the spring 27 (Fig. 2() at which point snap-action collapse of the toggle takes place.

During the course ofthe switch opening movement of the operating mechanism, the concave camming surface 56 of the guide member 21 engages roller 57 of the toggle and controls the movement thereof, whereby a substantially uniform rate of energy release by the spring 27 is obtained throughout the opening operation. At the conclusion of the opening operation, the anti-rebound member 59 is Vactuated'by its own inertia into reboundpreventing engagement with the fixed stop member 61, the blocking element 68 has moved out of engagement with the cooperating element 67 thereby releasing the operating member 28 foi-'return to its reset position, and the cutoff switch 72 remains actuated due to the engagement of its control arm 79 by protrusion 80 ,of the guide member 21 when Vin its unlatched position. See Fig. 3.

The operatingmechanism, in this particular embodiment of the invention, automatically undergoes a resetting operation immediately following the above-described opening operation. The force of spring 27 applied to the operating member 2S tends to move this member in a counterclockwise direction toward its reset position, and by means of pin 29 acting on the guide member arm 65,-the guide member 21 is simultaneously propelled in a counterclockwise direction toward its latchedposition. This causes the toggle knee 35 to follow a path which progressively converges with the path 29p of pin 29, thereby enabling the spring 27 to give up still more energy for effecting the resetting operation.

When 'the guide member 21 reaches its latched position, the latch 37 is automatically reset by the action of its biasing lspring 47 which tilts the intermediate latch member 42 clockwise so that its stud 44 engages the heel ofthe guide member leg'45, whereupon the trip shaft 40 returns to its normal position. See'Fig. 4. The cutoi switch72 is :now reset,the operating member 28 is in its reset position, and the plunger 31 has returned to its normal position Vin readiness for another closing operation.

While I have shown and described a preferred form ofy my invention by way of illustration, many modications will occur to those skilled in the art. I therefore contemplate by the claims which conclude this specication to cover all such modifications as fall within the true spirit and lscope of my invention, `What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a circuit interrupter: a movable switch member; a toggle comprising a pair of links pivotally joined to form a knee, one end of the toggle being connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; a movable operating member; electroresponsive means for moving the operating member from first to second predetermined positions when energized; an overcenter spring interconnecting the operating member and the toggle and eiective in response to movement of the operating member to its second position to produce snapaction switch closing movement of the toggle; and means including a pair of separable electric contacts actuated by a control arm for controlling the energization of the electroresponsive means, said control arm being disposed in cooperation with one of said toggle links for actuating said contacts and thereby deenergizing the electroresponsiveimeans in response to said snap-action switch closng movement of the toggle.

2. 'Inra circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the Switch member, said mechanism including a spring arranged kto release stored energy for producing switch closing movement of the mechanism; a movable `oper- 2@ ating member connected to the spring and 'disposed "for movement from tirst to second predetermined positions to control the accumulation of energy 'in the spring and to etect said release of stored energy by the-spring; electromagnetic means for moving the operating member comprising a solenoid and a magnetizable plunger coupled to the operating member and disposed for moving said operating member to its second position upon energization of the solenoid; and means including a pair of separable electric contacts actuated by a control arm for controlling the energization of the solenoid, said control arm being disposed in cooperation with the operating mechanism for actuating said contacts and thereby deenergizing the solenoid in response to said switch closing movement by said mechanism.

3. In a circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the switch member and including a spring arranged to release stored energy for producing switch closing movement of the mechanism; electromagnetic means for controlling the accumulation of energy in the spring comprising a solenoid for yproducing a magnetic eld when energized and an elongated magnetizable armature disposed for longitudinal movement in accordance with the magnetic force of said eld, said armature being coupled to the spring for stressing the spring and thereby accumulating energy therein while undergoing said longitudinal movement upon energization of the solenoid; and means including a pair of separable electric contacts actuated by a control arm mechanically independent of said armature for controlling the energization of the solenoid, said control arm being disposed for engagement by said operating mechanism upon switch closing movement thereof for causing said Vcontacts to separate thereby deenergizing the solenoid.

4. In a circuit interrupter: a movable switch member; a releasably latched force-transmitting linkage mechanism connected to the switch member; a helical spring havingV one end connected to the mechanism and arranged to release energy to the mechanism for imparting switch closing movement thereto; electromagnetic means for controlling the accumulation of energy in the spring comprising a solenoid for producing a magnetic field when energized and a magnetizable armature disposed for movement in accordance with the magnetic force of said eld, said armature being coupled to the other end of the spring for stressing the spring upon energization of the solenoid; and means for controlling the energization of the solenoid comprising a pair of cooperating electric contacts disposed for relative movement, means for moving one of the contacts from a disengaged position to an engaged position with respect to the other contact, and a control arm disposed for movement in response to said switch closing movement for actuating said one contact to its disengaged position thereby to deenergize the solenoid.

5. In a circuit interrupter: a switch member movable between open and closed circuit positions; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; an operating member disposed for movement from first to second predetermined positions; electroresponsive means for moving the operating member when energized; an overcenter spring interconnecting the operating member and the toggle to exert a switch closing force on said toggle during movement of the operating member toward its second postion; blocking means eiective during said operating member movement to nrevent movement of the switch member to its closed position until the o erating member reaches a point near its second position, whereupon the blocking means is rendered ineffective to prevent movement of the switch member and the toggle is able to undergo snapaction Switch closing movement in accordance with the force being exerted by the overcenter spring; and means including a pair of separable electric contacts actuated by a control arm for controlling the energization of the electroresponsive means, said control arm being disposed for movement in response to said snap-action switch closing movement of the toggle to actuate said contacts thereby deenergizing the electroresponsive means.

6. The circuit interrupter set forth in claim in which the electroresponsive means comprises a solenoid and a magnetizable armature coupled to the operating member for moving the operaing member when magnetically attracted by the solenoid upon energization thereof.

7. In a circuit interrupter: a movable switch member; a releasably latched operating mechanism connected to the switch member and including a spring arranged to release stored energy to the mechanism for imparting switch closing movement thereto; a movable operating member connected to the spring and disposed for movement from rst to second predetermined positions to control the accumulation of energy by the spring; electromagnetic means for moving the operating member to its second position comprising a solenoid and a magnetizable plunger coupled to the operating member and disposed for longitudinal movement, thereby moving the operating member and stressing the spring, upon energization of the solenoid; and means for controlling the energization of the solenoid comprising a base member subject to mechanical shock when the operating member attains its second position, a shaft supported by the base member and oriented with respect thereto so as to vibrate laterally as a result of said mechanical shock, a relatively stationary electric contact mounted on the base member, an assembly pivotally supported by the shaft including another electric contact disposed for movement between engaged and disengaged positions with respect to the stationary contact upon pivotal movement of the assembly, said contacts being electrically connected in series relationship in the energizing circuit for the solenoid, and means biasing the assembly in a predetermined direction about the shaft thereby normally maintaining the movable contact in said engaged position, said assembly including a control arm disposed for movement in response to said switch closing movement by the operating mechanism for actuating the movable contact to said disengaged position, the total mass of the assembly being distributed so that its center of gravity lies approximately in the plane of lateral vibration of the shaft with the movable contact in said engaged position, whereby the tendency for the assembly to move pivotally on the shaft upon the occurrence of said mechanical shock is minimized.

8. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; a movable operating member; electroresponsive means for moving the operating member from first to second predetermined positions when energized; an overcenter spring interconnecting the operating member and the toggle and eiiective in response to movement of the operating member to its second position with the guide member restrained in its latched position to produce snap-action switch closing movement of the toggle, said spring being eiective during movement of the operating member toward its second position to drive the guide member toward its unlatched position in the event of guide releasing operation by the latch; and means including a pair of separable electric contacts actuated by a control arm for controlling the energization of the electroresponsive means, said control arm being disposed in cooperation with the guide member for actuating said contacts and thereby deenergzing the electroresponsive means during movement of the guide member toward its unlatched position.

9. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; a movable operating member; electromagnetic means for moving the operating member from first to second predetermined positions comprising a solenoid and a magnetizable armature coupled to the operating member for moving the operating member toward its second position in response to energization of the solenoid; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its second position with the guide member restrained in its latched position to produce switch-closing movement of the toggle, said spring being effective in response to movement of the operating member toward its second position with the guide member released by the latch to drive the guide member toward its unlatched position without causing switch closing movement of the toggle; and means including a pair of separable electric contacts actuated by a control arm for controlling the energization of the solenoid, said control arm being disposed for engagement by said guide member during movement thereof toward its unlatched position for causing said contacts to separate thereby deenergizing the solenoid.

10. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; a movable operating member; electroresponsive means for moving the operating member from tirst to second predetermined positions when energized; an overcenter spring interconnecting the operating member and the toggle and etective in response to movement of the operating member from its rst to its second position with s aid other end of the toggle restrained in its latched position to move the toggle from a collapsed condition to a straightened condition by imparting snap-action switch closing movement thereto; means responsive to toggle releasing operation of the latching means during said operating member movement to move the toggle in its collapsed condition thereby preventing switch closing movement thereof; and means for controlling the energization of the electroresponsive means including a pair of separable electric contacts and a control arm movable from one position to another position to actuate the contacts and thereby deenergize the electroresponsive means, said control arm being disposed for movement to said other position in response to the movement of the toggle in its collapsed condition.

l1. In a circuit interrupter: a movable switch member; a latch member; an operating mechanism connected to the switch member, said mechanism comprising a plurality of interconnected movable members, one of which is disposed to be releasably restrained in a latched position by the latch member, and a spring arranged to release stored energy for imparting switch closing movement to the mechanism, said mechanism being arranged to undergo switch opening movement in response to release of said one member by the latch; a movable operating member connected to the spring and disposed for movement from rst to second predetermined positions to control the accumulation of energy by the spring; electroresponsive means for moving the operating member to its second position when energized; and means for controlling the energization of the electroresponsive means including a pair of separable electric contacts actuated by a control arm, said control arm being disposed for engagement by said one member during said switch openingmovement of the operating mechanism for vcausing said contacts to be separated. y

12. AIn acirc'uit interrupter: a switch member disposed for movement between'open and closed circuit positions; aftoggle comprising a pair'of pivotally interconnected links, one end of the toggle being connected to the switch member; a guide member connected to the otherend of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide lmember in'its latched position; a movable operating member; electroresponsive means for moving the operating member Afrom first to second'predetermined positions when energized; an overcenter spring interconnecting the operating member and the toggle and etective in response to movement of the operating member to its second position'to produce snap-action switch closing movement of the toggle; means responsive to guide releasing operation of the latch to drive the guide member to' its unlatched position for effecting switch openn ing movement of the toggle; means for energizing the electroresponsive means whenever switch closing operation is desired; and means for deenergizing the electroresponsive means comprising a pair of separable electric contacts actuated by a controlV arm, said control arm being disposed in cooperation with one of said toggle links to actuate said contacts and maintain the electroresponsive means de-energized whenever the switch member is in its closed circuit position and during an initial portion of said switch opening movement of the toggle, said control arm aiso being disposed in cooperation with the guide Vmember to maintain said contacts actuated and thereby prevent energization of the electroresponsive means during the remaining portion of said switch opening movement of the toggle and foras long as the guide member is in its unlatched position.

13. In a circuit interrupter: a switch member disposed for movement between open and closed circuit positions; a toggle having one end connected' to the switch member; a guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; a movable operating member; electromagnetic means for moving the operating member from rst to second predetermined positions, said electromagnetic means comprising a solenoid and a magnetizable armature coupled to the operating member and disposed for moving said operating member to its second position upon energization of the solenoid; an overcenter spring interconnecting the operating member and toggle and effective in response to movement of the operating member to its second position to produce snap-action switch closing movement ofthe toggle, said over-center spring being effective in response to guide releasing operation of the latch to drive the guide member to its unlatched position and produce switch opening movement of the toggle; and means for controlling the energization of the solenoid including a pair of separable electric contacts and a control arm movable from one position to another position to actuate the'contacts and thereby deenergize the solenoid, said control arm, in cooperation with the toggle, being disposed for movement to said other position in response to'said snap-action switch closing movement of the toggle and, in cooperation with the guide member, being prevented from returning to said one position whenever the guide member is in its unlatched position.

14. In a circuit interrupter; a movable switch member; a toggle having one end connected to the switch member; latching means for releasably restraining the other end of the toggle in a latched position; a movable operating member; electroresponsive means for moving the operating member from rst to second predetermined positions when energized; an overcenter spring interconnecting the operating member andthe toggle :and eiectivein response to movement of the operating member toits second position to produce snap-action switch .closing movement of the toggle, said overcenter spring Vbeing effective to collapse the toggle in response to toggle releasing operation ofthe-latching means; and means for controlling the energization of the electroresponsive means including a pair of separable electric contacts and a control arm movable from one position to another position to actuate the contacts and thereby deenergize the electroresponsive means, said control arm being disposed for movement to said other position in response to said snap-action switch closing movementrof the toggle and'being maintained in said other position in response to said toggle collapse.

l5. In a circuit interrupter: a movable switch member; a latch member; an operating mechanism connected to the switch member, said mechanism comprising a plurality of interconnected movable members, one of which is releasablyV engageable by the latch member, and a spring arranged to release stored energy for imparting switch closing movement to the mechanism with said one member engaged by the latch, said mechanism being arranged to undergo switch opening movement in response to release of said one member by the latch; a movable operating member connected to the spring and disposed for movement from iirst to second predetermined positions to control the accumulation of energy by the spring and to eiiect said release of stored energy; electroresponsive means for moving the operating member when energized; and means for controlling the energization of the electroresponsive means comprising a pair of separable electric contacts actuated by a control arm, said control arm being disposed for engagement by a member of said mechanism other than said one member to actuate said contacts and thereby deenergize the electroresponsive means in response to said switch closing movement of the mechanism, said control arm also being disposed for engagement by said one member to prevent energization of the electroresponsive means in response to said switch opening movement of the mechanism.

i6. In a circuit interrupter; a switch member disposed for movement between open and closed circuit positions; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch for releasably restraining the guide member in its latched position; a movable operating member; electroresponsive means for moving the operating member from irst to second predetermined positions when energized; an overcenter spring interconnecting the operating member and the toggle to exert a switch closing force on the toggle during movement of the operating member toward its second'position; blocking means eective during said operating member movement to prevent movement of the switch member to its closed position until the operating member reaches a predetermined point near its secon-d position, whereupon the blocking means is rendered ineffective to prevent movement of the switch member and the toggle is able to undergo snap-action switch closing movement in accordance with the orce being exerted by the overcenter spring; means responsive to guide releasing operation of the latch to drive the guide member to its unlatched position for effecting switch opening movement or" the toggle; and means for controlling the energization of the electroresponsive means including a pair of separable electric contacts and a control arm movable from one position to another position to actuate the contacts and thereby deenergize the electroresponsive means, Vsaid control arm in cooperation with the toggle, being disposed for movement to said other position in response to said snap-action switch closing movement of the toggle and, in cooperation with the guide member, being prevented from returning to said one position whenever the guide member'is in its unlatched position.

17. The circuit 'interrupter ct claim 1:6 in Vwhich the electroresponsive means, the mass of said electroresponsive means comprises a solenoid and a magnetizable armature coupled to the operating member for moving the operating member toward its second position in response to energization of the solenoid.

18. In a circuit interrupter: a movable switch member; a latch member; an operating mechanism connected to the switch member, said mechanism comprising a plurality of interconnected movable members, one of which is releasably engageable by the latch member, and a spring arranged to release stored energy for imparting switch closing movement to the mechanism with said one member engaged by the latch, said mechanism being arranged to undergo switch opening movement in response to release of said one member by the latch; a movable operating member connected to the spring and disposed for movement from iirst to second predetermined positions to control the accumulation or" energy by the spring; electroresponsive means for moving the operating member to its second position when energized; and means for controlling the energization of the electroresponsive means comprising a base member subject to mechanical shock upon attainment of said second position by the operating member, a shaft supported by the base member and oriented with respect thereto so as t vibrate laterally as a result of said mechanical shock, a relatively stationary electric contact mounted on the base member, a resilient switch arm pivotally supported by the shaft, said switch arm including another electric contact normally disposed in engagement with the stationary contact and said contacts being electrically connected in series relationship in the energizing circuit of the electroresponsive means, and a control arm coupled to the switch arm and pivotally movable from one position to another position to actuate the switch arm thereby separating the electric contacts and deenergiz'ng the switch and control arms being distributed so that collectively their center of gravity lies approximately in the plane of lateral vibration of the shaft with the control arm in said one position, whereby the tendency for the switch arm to move relative to the stationary contact upon the occurrence of said mechanical shock is minimized; said control arm, in cooperation with a member of said operating mechanism other than said one member, being disposed for movement to said other position in response to said switch closing movement of the mechanism and, in cooperation with said one member, being prevented from returning to said one position in response to said switch opening movement of the mechanism.

19. An electric switch comprising: a base member subject to mechanical shock; a shaft supported by the base member and oriented with respect thereto so as to vibrate laterally as a result of said mechanical shock; a relatively stationary electric contact mounted on the base member; a resilient switch arm pivotally supported by the shaft, said switch arm including another electric contact disposed for movement between engaged and d sengaged positions with respect to the stationary contact upon pivotal movement of the switch arm; a cantilever control arm yieldably connected to the switch arm for actuation thereof; and means biasing the switch and control arms in a predetermined direction about the shaft thereby normally to maintain the movable contact in one of its two positions; the mass of said arms being distributed so that the center of gravity of the physical system formed by these interconnected arms lies approximately in the plane of lateral vibration of the shaft whenever the arms are disposed with said movable contact in said one position, whereby the tendency for the switch arm to move relative to the stationary contact upon the occurrence of said mechanical shock is minimized.

20. An electric switch comprising: a base member subject to mechanical shock; a shaft supported by the base member and oriented with respect thereto so that the principal vibratory motion of the axis of theshaft as a result of said mechanical shock defines a predeterL mined plane; a relatively stationary electric contact mounted on the base member; a resilient switch arm pivotally connected to the shaft, said switch arm including another electric contact disposed for movement between engaged and disengaged positions with respect to the stationary contact upon pivotal movement of the switch arm; a cantilever control arm coupled to the switch arm for actuation thereof; and means biasing the switch and control arms in a predetermined direction about the shaft to predetermined normal positions wherein the movable contact is maintained in one of its two positions; said switch and control arms when in their normal positions being asymmetrically disposed with respect to said predetermined plane and having their respective masses so distributed that collectively their center of gravity is disposed approximately in said predetermined plane, whereby the tendency for the switch arm to move relative to the stationary contact upon the occurrence of said mechanical shock is minimized.

21. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a movable guide member connected to the other end of the toggle and disposed to carry said other end along a predetermined path while moving from latched to unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; stop means disposed to determine said unlatched position of the guide member; an operating member disposed for movement from first to second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its second position with the guide member in its latched position to produce snap-action switch closing movement of the toggle, said second position of the operating member being so located in relation to the toggle after said switch closing movement thereof that the line of action of the spring force intersects said predetermined path; said overcenter spring being effective in response to subsequent guide releasing operation of the latch to drive the guide member to its unlatched position and produce snap-action switch opening movement of the toggle; and means disposed in cooperation with the toggle and effective while the guide member is moving toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation.

22. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a pivotally mounted guide member connected to the other end of the toggle and disposed to carry said other end along a predetermined arcuate path while moving between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; stop means disposed to determine said unlatched position of the guide member; a helical spring having one end connected to the toggle and the other end disposed at a predetermined point so located in relation to the toggle that the line of action of the spring force intersects said predetermined arcuate path, said spring being effective in response to guide releasing operation of the latch to drive the guide member to its unlatched position and produce snap-action switch opening movement ofthe' toggle; and cam means integrally' associated with the guide member and disposed to engage the toggle while the guide member is moving toward its unlatched position for controlling the resulting movement of said one end of the spring in a manner to obtain a substantially uniform rate of energy release by the spring throughout the opening operation,

23. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle-andsupported for movement betweenllatched :anomalo and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; an operating member disposed for movement between first and second predetermined positions at opposite ends of its normal range of movement; stop means disposed to determine said second position of the operating member; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position with the guide member in its latched position to produce snap-action switch closing movement of the toggle, said overcenter spring being effective in response to gunde releasing operation of the latch to drive the guide member to its unlatched position and produce switch opening movement of the toggle; means disposed in cooperation with the toggle and effective while the guide member is moving toward its unlatched position to control the resulting movement of the toggle in a manner to `obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation; and means for subsequently returning the operating member to its first position and for simultaneously driving the guide member to its latched position.

24. In a circuit interrupter: a switch member disposed for circuit opening and closing movement; a toggle having one end connected to the switch member; a movable guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; an operating mem-ber disposed for movement between first and second positions at opposite ends of its normal range of movement; stop means disposed to determine said second position of the operating member; an overcenter spring interconnecting the operating member and the toggle and eective in response to movement of the operating member from its first to its second position to produce snap-action switch closing movement of the toggle; blocking means disposed to releasably restrain the operating member in its second position with the switch member closed; said overcenter spring being eiiective in response to guide releasing operation of the latch to drive the guide member to its unlatched position and produce switch opening movement of the toggle; means controlled by movement of the guide member toward its unlatched position to engage the toggle and control the resulting movement thereof in a manner to obtain a substantially uniform rate of energy released by the overcenter spring throughout the opening operation; said blocking means being arranged to free the operating member for return to its first position in response to the opening operation; and means for subsequently returning the operating member to its first position and simultaneously driving the guide member to its latched position.

25. In a circuit interrupter: a movable switch member; a toggle having one end connected to the switch member; a movable guide member connected to the other end of the toggle and disposed to carry said other end along a predetermined path while moving between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; first stop means disposed to determine said unlatched position of the guide member; an operating member disposed for movement between first and second predetermined positions; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member to its second position with the guide member in its latched position to produce snap-action switch closing movement of the toggle; second stop means disposed to determine said second position of the operating member which position is so located in relation to the toggle after said switch closing movement thereof that the line of Yaction of the force of the overcenter spring intersects the pre- -determined path of movement of said other end of the toggle; said overcenter spring being effective inresponse to subsequent guide releasing operation of the latch to drive the guide member to its unlatched position and produce snap-action switch opening movement of the toggle; means disposed in cooperation with the toggle and effective while the guide member is moving toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation; and means for returning the operating member to its first position while simultaneously driving the guide member to its latched position.

26. In a circuit interruptor: a movable switch member; a toggle comprising a pair of pivotally interconnecting links, one end of the toggle being connected to the switch member; a roller rotatably supported by one of the toggle links; a guide member connected to the other end of the toggle and disposed for movement between latched and unlatched positions; a latch disposed releas- -ably to restrain the guide member in its latched position; a movable operating member; and an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from first to second predetermined positions with the guide member in its latched position to produce snap-action switch closing movement of the toggle, said overcenter spring being effective to drive the guide member to its unlatched position and produce switch opening movement of the toggle in response to subsequent guide releasing operation of the latch; said guide member including a concave camming surface disposed to engage said roller while moving toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation.

27. In a circuit interrupter: a movable switch member; a toggle comprising a pair of links pivotally joined to form a linee, one end of the toggle being connected to the switch member; a guide member connected to the other end of the toggle and supported for pivotal movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; a movable operating member; an overcenter spring interconnecting the operating member and the toggle knee and effective in response to movement of the operating member from first to second predetermined positions with the guide member in its latched position to produce snap-action switch closing movement of the toggle, said overcenter spring being effective in response to subsequent guide releasing operation or the latch to drive the guide member to its unlatched position and produce switch opening movement of the toggle; and a roller rotatably supported by one of said toggle links intermediate said one end and said knee; said guide member having a camming surface disposed to engage said roller while said guide member is moving pivotally toward its unlatched position, said camming surface beting contoured so that the camming action of thi surface forces the roller and consequently the toggle knee to follow relutively linear paths during the opening operation.

28. in a circuit interrupter: a switch member disposed for movement between closed and open circuit positions; latching means; an operating mechanism connected to the switch member and vto the latching means, said mechanism being operable from a reset condition to a closed condition while releasably latched by the latching means for producing circuit closing movement of the switch member and being operable to an open condition in response to subsequent unlatching ope-ration of the latching means for producing circuit opening movement of the switch member; means for preventing appreciable rebound of the switch member from open circuit posi- 29 tion upon completion of said circuit opening movement comprising, an anti-rebound member pivotally connected to the switch member, said anti-rebound member being disposed in a rst predetermined position with the switch member in its closed circuit position, means for guiding the anti-rebound member so that it travels with essentially translation motion from its iirst position to a second 'predetermined position in response to movement of the switch member from closed to open circuit positions, said anti-rebound member being rotatable from its second position in a predetermined direction with respect to the point of its pivotal connection to the switch member, and a cooperating member rxedly disposed to be engaged by the anti-rebound member upon rotation thereof for preventing movement of the anti-rebound member directly toward its rst position and thereby preventing appreciable rebound of the switch member, said antiarebound member having its center of gravity located so that its 4inertia at the moment of reaching its second position will cause said rotation and so that 4the force of gravity will return it to its second position; and means for effecting a resetting operation of said mechanism from its open condition to its reset condition; s aid mechanism including means disposed in cooperation with said anti-rebound member when the mechanism is in its reset condition to prevent said rotation of the anti-rebound member during the initial phase of the circuit closing movement of the switch member.

29. In a circuit interrupter: a switch member disposed for movement between closed and open circuit positions; an operating mechanism connected to the switch member for producing circuit opening movement thereof; and means for preventing appreciable rebound of the switch member from its open circuit position upon the completion of said circuit opening movement comprising, an

anti-rebound member pivotally connected to the switch member, said anti-rebound member being disposed in a iirst predetermined position with the switch member in its closed circuit position, means for guiding the antirebound member so that it Itravels with essentially translational motion from its rst position to a second predetermined position in response to movement of the switch member from closed to open positions, said guide means being disposed to permit rotation of the anti-rebound member from its second position in a predetermined direction with respect to the point of its pivotal connection to the switch member, and a cooperating member ixedly disposed to be engaged by the anti-rebound member upon rotation thereof for preventing movement of the anti-rebound member directly toward its first position and thereby preventing appreciable rebound of the switch member, the center of gravity of the anti-rebound member being located so that the kinetic venergy of this member at the moment it reaches its second position produces said rotation and so that the force of gravity acting on this member returns it to its second position when said kinetic energy has been dissipated.

30. In a circuit interrupter: a switch member disposed for movement between closed and opened circuit positions at opposite ends of its normal range of movement; an operating mechanism connected to the switch member for producing circuit opening movement thereof; and means for preventing appreciable rebound of the switch member from its open circuit position upon the completion of said circuit opening movement comprising, an elongated member connected near an upper end thereof to the switch member for pivotal movement in avertical plane, the axis about which said pivotal movement Vtakes yplace being moved along in an arcuate path in' said vertical plane in response to movement of the switch member from closed to open circuit positions, means for supporting the elongated member in a predetermined inclined position whenever the switch member is in its closed circuit position and for guiding the elongated member during movement of said axis so that it travels with essentially translational motion from its inclined position to another predetermined position substantially parallel to said inclined position, said supporting and guiding means being disposed to permit rotation of the elongated member from its other position in a predetermined direction about said axis, and a rigid member fixedly disposed for interlocking engagement, upon rotation of the elongated member, by a laterally protruding portion of the elongated member located near its other end, the elongated member being rotated in said predetermined direction by the force of inertia etfective at the conclusion of said translational motion and being subsequently returned to said other position by the force of gravity.

31. In a circuit interrupter: `a switch member movable between closed and open circuit positions; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and supported for movement between latched and unlatched positions; a latch disposed releasably to restrain the guide member in its latched position; an operating member disposed for movement between tirst and second predetermined position at opposite ends of its normal range of movement; stop means disposed to determine said second position of the operating member; an overcenter spring interconnecting the operating member and the toggle and effective in response to movement of the operating member from its first to its second position with 4the guide member in its latched position to produce snap-action switch closing movement of the toggle, whereby the switch member is moved from open to closed circuit positions; said overcenter spring being effective in response to guide releasing operation of the latch to drive the guide member to its unlatched position and produce switch opening movement of the toggle, whereby the switch member is moved from closed to open circuit positions; means disposed in cooperation with the toggle and effective while the guide member is moving toward its unlatched position to control the resulting movement of the toggle in a manner to obtain a substantially uniform rate of energy release by the overcenter spring throughout the opening operation; means for preventing appreciable rebound of the switch member from its open circuit position at the conclusion of the opening operation comprising an anti-rebound member pivotally connected to the switch member, said anti-rebound member being guided for translational movement in response to the circuit opening movement of the switch member and being rotatable in a predetermined direction with respect to the point of its pivotal connection to the switch member with the switch member in its open circuit position, and a cooperating member iixedly disposed to be engaged by the anti-rebound member upon rotation thereof in said predetermined direction for preventing appreciable movement of the switch member toward its closed circuit position, and anti-rebound member having its center of gravity located so that its inertia at the conclusion of the opening operation will cause said rotation in opposition to gravitational force acting thereon; means for returning the operating member to its irst position and for simultaneously driving the guide member to its latched position thereby resetting the toggle and the latch; and means associated with the toggle and disposed in cooperation with said anti-rebound member whenever the guide member is in its latched position and the switch member is in its open circuit position for preventing said rotation of the anti-rebound member during the linitial phase of the circuit closing movement of the switch member. 'V

32. In a circuit interrupter: a switch member movable between closed and open circuit positions; a toggle having one end connected to the switch member; a guide member connected to the other end of the toggle and supported for movement between latched and unlatched