US2025697A - Circuit interrupter - Google Patents

Description

Dec. 24, 1935. B p BAKER 2,025,697

CIRCUIT INTERRUPTER Filed April 22, 1933 3 Sheets-Sheet 1 VIII/l.

WITNESSES: INVENTOR ATTORNEY Dec. 24, 1935. B AKER 5 2,025,697

CIRCUIT INTERRUPTER Filed April 22, 1933- 5 Sheets-Sheet 2 Ill/III, III! WITNESSES: INVENTOR ,ficy mvfi P547126? Owl Q. W BY ATTORNEY Dec. 24, 1935. B P BAKER CIRCUIT INTERRUPTER Filed April 22, 1933 s Sheets-Sheet a I I 62 25 g WITNESSES:

' AT1:OR EY' Patented Dec. 24, 1935 PATENT OFFICE 2,025,697 CIRCUIT INTERRUPTER Benjamin r. Baker, 'ruruecma'ra, magnolto Westinghouse Electric & Manufacturing Com- Pa y, East Pittsburgh, Pa.,

Pennsylvania a corporation of Application April 22, 1933, Serial No. 667,377-

13 Claims.

My invention relates to circuit breakers and particularly to circuit breakers of the quick-make and quick-break type which utilize non-resilient or butt type contact members.

It is an object of my invention to generally improve upon the operating mechanisms heretofore used in such breakers, in order to secure a simpler, more compact, and more rugged mechanism that shall be more economical to manufacture, and that shall be more satisfactory and more dependable in operation than the previously known structures.

It is also an object of my invention to provide an improved means for supporting the moving 1.; contact member of a quick-make and quickbreak circuit interrupter; my improved supporting means to include a lost motion connection between the contact member proper and the frame of the switch member.

23 Another object of my invention is to provide an improved switch member for use in circuit interrupters; my improved switch member to include a spring biased, pivotally mounted contact member and means for causing the contact mem- 5 her to assume a free or fioatirm position when the circuit interrupter is in the closed position.

A further object of my invention is to provide improved means for causing the separation of circuit breaker contacts, having main and aux- :30 iliary contact surfaces to occur, in a predetermined manner.

A further object of my invention is to prevent the welding of the engaging contacts of a circuit interrupter utilizing non-resilient or butt type 3 contact members.

A still further object of my invention is to provide combined mechanical and magnetic means for preventing injury to the main current-carrying surfaces of a circuit interrupter utilizing main 4:) and auxiliary contacts.

The principal field for immediate application of my invention is in connection with circuit breakers for controlling lighting and distribution feeder circuits, and I shall hereinafter describe 4; an embodiment of my invention as applied to such circuit breakers, without, however, in any way intending'to restrict the scope of my invention except as indicated in the appended claims.

In this embodiment of my invention, I provide 5') a plurality of switch members, each of which includes a contact member having main and auxi'iary contact surfaces, and a plurality of stationary contact members for cooperating therewith to open and close a plurality of poles. In 55 addition, I provide a manually operable mechanism for opening and closing the circuit breaker contacts with a snap action, an insulating base upon which the structure is assembled, a contact pressure securing spring for biasing each of the switch members to the open position, a releasable 5 restraining means associated with the operating mechanism for restraining each of the switch members in the closed position, and a trip device for releasing the restraining means in response to a predetermined electrical condition in any 10 one pole, thereby opening all of the poles of the breaker.

The features of my invention which I believe to be new are particularly pointed out in the appended claims, and for a full understanding of the principles of the invention, reference may be had to the accompanying drawings in which:

Figure l is a fragmentary perspective view of a three-pole circuit breaker embodying the principal elements of my invention; the cover, portions of the upstanding sides of the circuit breaker base, and one side of the frame of the circuit breaker operating mechanism have been cut away to more clearly illustrate the structural features involved;

Fig. 2 is an enlarged view, partially in section, along the longitudinal axis of one of the outer switch members of the circuit breaker shown in Fig. 1, the circuit breaker being in the fully closed position;

Fig. 3 is a view similar to Fig. 2 showing the initial stage of the circuit opening operation;

Fig. 4 is a view similar to Figs. 2 and 3 showing the disposition of the various contact parts at the instant of arc initiation; 38

Fig. 5 is a rear elevational view, with parts in section, of the circuit breaker operating mechanism and the switch member frame;

Fig. 6 is a fragmentary perspective view showing the circuit breaker operating mechanism; 40

Fig. 7 is a fragmentary perspective view showing the bearing portion of one of the bifurcated elements which make up the operating member for the circuit breaker operating mechanism;

Fig. 8 is a fragmentary perspective view showa ing one of the pressure-securing springs and the main bearings for the assemblage of switch members; I

Fig. 9 is a fragmentary view, partially in section, showing the disposition of the various parts of the circuit breaker mechanism in the fully closed position;

Fig. 10 is a view similar to Fig. 9 showing the intuit breaker in the open position; and

Fig. 11 is a view similar to Figs. 9 and 10 showing the circuit breaker in the tripped position.

Referring to the drawings, the base i is of molded insulating material and has mounted thereon the stationary contact assemblages 3, and the circuit breaker operating mechanism 5 which has associated therewith the assemblage of the switch members i and theoutboard bearings 9. The switch members i and the stationary contact assemblages 3 combine to form the plurality of poles. The several poles are insulated from each other by means of the insulating barriers i I which are molded in the base I, the barriers H aligning with similar barriers in the cover (not shown).

The operating handle I3 is likewise of molded insulating material. A portion of the trip device 95 is shown in Figs. 9, 10, and 11. The trip device 85 includes a base I6 of insulating material and terminal members I8 and 2B. The terminal members i B are connected to the ends of the flexible shunts 23 by means of the stud bolts 22, and the terminal members 20 are connected to the circuit breaker terminals 26 through the agency of the stud bolts 26 The electrical circuit for each of the poles is substantially the same. Beginning with the terminal 2, the current passes successively through the stationary contact assemblage 3, the main contact I! and the arcing contact E9, the coopcrating moving contact 2| associated with each of the switch members i, the conducting shunt 23--the end 26' of each of the shunts 23 connecting, as'mentioned above, with the terminals iii of the trip device-and then through the trip device I5 to the other terminal 24. Each of the switch members i has a channelshaped frame 25 of iron, upon which the remainder of the structure is assembled. The moving contact 2 I is pivotally supported on the iron frame 25 by means of a pivot pin 27, which extends through slotted openings 29 in the opposed sides thereof. Cotter pins 3| are provided for preventing endwise motion of the pin 21 and thereby restraining the pin in operative position. The flexible shunt 23 is brazed or otherwise conductively joined at one end to the center of the moving contacts 2 l, and, as previously mentioned, is provided with a portion 24 for engaging the terminals of the trip device. Each of the moving contact members 2| has a main current-carrying surface 33, preferably of silver, which is adapted to engage a cooperating surface 35, preferably of a silver-tungsten alloy, which forms a part of the main stationary contacts ll.

Each of the moving contacts 2i is further provided with an arcing portion 31, which engages a similar portion 39 forming a part of the auxiliary contact l9 during the operation of the circuit interrupter. Each ofthe contact members 2| is biased counter-clockwise above its pivot 21 by a leaf spring M (Fig. 8). This spring 4! provides the normal contact pressure between the engaging surfaces when the circuit interrupter is in the closed position. i

The frames 25 of the three switch members 7 are rigidly fastened together by means of a steel tie-bar 63, which extends across aii of the poles of the breaker. This bar is afiixed to the pivoted end of each of the switch member frames 25 by means of an iron strap 45 which loops about the bar 43 and has projections id (Figs. 2, 3 and 4) which extend through the openings 41 (Fig. 6)

'in the frame 25 and are therein clinched. An insulating tube 69 is disposed about the tiebar 43 in order to prevent the short circuiting of the poles.

The bar 63 serves to mechanically interconnect all of the switch members i, and thereby makes it possible to operate all three of the switch members from a single operating mechanism. Also, this bar provides a means whereby all of the poles 5 of the breaker are opened and c!osed simultaneously.

As shown particularly in Figs. 2, 3, and 4, each of the contact members 2! includes a tail portion 5| which is adapted to extend toward the pivoted 10 end of its associated switch member frame. One of the flexible shunts 23, which I prefer to form of a plurality of fiat copper laminations, is afiixed to each of the moving contact members 2! directly beneath the passage through which the pivot pin 21 extends. This means that a portion of the shunt 23 extends along the tail portion 5| at all times during the operation of the circuit interrupter, and since the channel-shaped frame 25 is of irona magnetic material-the flexible shunt is attracted toward the closed end of the channel, and the force of the contact pressuresccuring spring M is augmented at all times by an additional force substantially proportional to the magnitude of the current then being carried. This attractive force has the further effect of aiding the rotation of the movable contact member during the opening movement of the switch member. This is of considerable value in securing reliable operation of the circuit breaker, and,

as will be pointed out later, is of great assistance in preventing the burning of the main currentcarrying surfaces 33 and 35.

A pin 53 (Fig. 8) extends through suitable openings in each of the frame members 25, and is 35 adapted to engage and position the tubular bearing members 55. The bearing members 55 of the central frame engage suitable openings in a frame 63 of the operating mechanism, and the bearing members 55 in the switch member frame of each of the outer poles engage the outboard bearing support 9 (Fig. l). The pin 53 is also used for positioning the leaf, contact pressure securing spring M. As shown in Figs. 2, 3 and 4, the leaf spring 4| is prevented from motion along the longitudinal axis of the channel-shaped frame by the engagement of the semi-circular portion 51 with the central portion of the pin 53, and it engages the body portion of the frame 25 at the point 59. No fastening means other than the portion 57 is necessary to hold the spring 4! in position due to its being under stress at all times.

A suitable raised portion Si is provided on the upper side of each of the contact members 2i for engaging the free end of the leaf spring 6|. The raised portion 3! is so located that the line of action of the contact pressure-securing spring is made to fall between the engaging contact surfaces. This feature, in combination with the novel contact mounting means shown in this em- 60 bodiment of my invention, is of great value in securing reliable and satisfactory operation of the circuit breaker.

The operating mechanism 5 comprises, in general, a U-shaped base 63, a pair of toggle links 65 and 67 for engaging the assemblage of the switch member 1, a trigger 69 for releasably restraining the toggle links 65 and 67 in operative position, a bifurcated operating lever ll, overcenter springs 13 for connecting the operating 70 lever ll to the knee pivot pin 15 of the toggle links, and the operating handle l3. The U- shaped base 63 is fastened to the insulating base I of the circuit breaker proper by means of four screws ll (Figs. 9 to 11), two at each end, which extend through suitable openings 18 (Fig. 6) in the base of the frame,-88. The central switch member, as previously pointed out, is directly pivoted to the U-shaped frame by one of the pins 53 and its associated bearing members 55.

The lower end of the bifurcated toggle link 81 is pivotally connected to the frame 25 of the central switch member by a pin 18 which serves to connect the operating mechanism to the as-' semblage of the switch members 1. The single end 88 of the bifurcated toggle link 81 engages the knee pivot pin 15 midway between the pair of opposing link members, which together make up the toggle link (Figs. 5 and 6). The'other end of the toggle link 85 engages a trigger through a pin 8i. A rivet 82 connects and positions the parallel sections which make up the link 55. The knee pivot pin 15 has means associated therewith for engaging one end of each of the over-center operating springs 13, one at either end of the pin. The other end of the operating springs 13 is connected to the operating lever 1i.

The trigger 89 is pivotally mounted upon a pin 83 extending through suitable aligned openings in the side of the U-shaped frame.

It will be noted (Fig. 6) that the pin 83 is of large diameter,.and as a result has considerable mechanical strength and rigidity. This is necessary because the pin 83 is used as a stop for defining the upward limit of motion of the central switch member 1 and the interconnected outer switch members during the opening operation. A slotted opening 85 is provided in the frame 25 of the central switch member 1 in order to clear the trigger 89. The unsupported end of the trigger 68 has a portion 81 which is adapted to engage the overhanging latch 88 of the trip device I5.

The movement of the bifurcated operating lever II is limited by the projections 9i and 83 (Figs. 9, l0, and 11) which extend inwardly from the sides of the U-shaped base 83. The ends of the bifurcated operating member 1| are pivotally supported on the sides of the frame 83 by means of the bearing element shown particularly in Fig. '7. Tlnsin'cludes a struck-in portion 85 having a flat strip 88 of bearing material disposed thereon. The strip 88 is rounded on its upper portion and is adapted to be-engaged by a notch I88 positioned in the lower end of each of the side portions of the operating lever 1|. This type of bearing assemblage forms a very convenient and very satisfactory means for supporting the operating handler Lacking apin, it is readily assembled and is cheap in cost, and since the over-center operating springs 13 exert a downward component of force upon each of the side members of the operating lever! I, there is no possibility of the operating lever disengaging the bearing assemblage.

My invention is not particularly concerned with the trip device I5 and any electro-responsive mechanism which is capable of releasably engaging the end 81 of the trigger 88 and which latch 83, which'isradapted to rotate on the pivot pin 88 includes a pair of side portions I8I having slotted openings I83 therein, an overhanging portion I85 which engages the end 81 of the trigger 58, and a spring I81 which biases the latch in a counter-clockwise direction about the pivot pin 88. The counter-clockwise movement of the latch 88 is limited by an upstanding portion I88 of one of the sides of the supporting bracket 81. Movement in a clockwise direction is prevented by electro-responsive latch means associated with the trip device. The slots I83 are used for making the trip device automatically resettable; they permit a lateral sliding movement of the latch 88 in the direction of the base I8 of the trip device I5 during the resetting operation and thus make possible the re-engaging of the overhanging portion I85 and the end 81 of the trigger 88. The trip device I5 is supported upon its terminals I8 and 28 which are of sumcient rigidity to accurately position the device with respect to the operating mechanism 5.

The operation of this embodiment of my invention may best be described in conjunction with Figs. '2 to 4 and Figs. 9 to 11. In Fig. 10 the operating mechanism and the circuit breaker contacts are shown in the normal open circuit position. It will be seen that the frame 25 of the central switch member is in abutting engagement with the pin 83 which serves as a stop in defining the upward-limit of travel of the assemblage of the switch members 1. It will further be noted that the toggle links 55 and 81 have collapsed so as to move the knee pivot pin 15 in the-direction of the trip device I5. This movement of the knee pivot pin 15 brings the line of action of the operating springs 13 to the right of the bearing portion of the operating lever 1|, and as a result the operating lever H is biased in a clockwise direction into engagement with the projections 8|. The handle I3 is thus retained in the position shown in Fig. 10. The end 81 of the trigger 58 is restrained in position by the overhanging portion I85 of the latch 88.

To close the contacts manually the handle I3 is moved in the counter-clockwise direction about its bearing. Shortly before the handle reaches the fully on position the line of action of the over-center springs 13 is moved across the center line of the toggle link 65 (that is, the line a closed position. The movement of the knee pivot pin 15 results in a progressive increase in the component tending to move the toggle to the closed position, and as a result, the switch member frames and the contacts are caused to move in the position shown in Fig. 9 with a snap action.

The electrical circuit is first established between the arcing surface 31 of each of the moving contacts 2| and the cooperating portion 39 of the stationary contacts I9. This is shown in Fig. 4. Next, each of the contacts 2| rotates about the pivot pin 21, increasing the downward force of the spring 4| and ultimately causing the engagement of the main contact surfaces 33 and 35, as is shown in Fig. 3. The engagement of the main contact surfaces takes place before the switch members have been moved to the fully on position shown in Fig. 2. However, this additional movement of the contact frames 25 is not transmitted to the moving contact members M because of the lost motion connection which is supplied by the slots 29 wherein each of the pivot pins 21 move. Thus, the final stages of the closing operation cause each of the contact members 2! to become a floating three-force member with respect to the associated switch member frame 25, the pins 29 not moving to the top of the slot when the frames. are in the fully closed position. In-order to accomplish this, it p is practically necessary that the point of application of the contact pressure securing spring be somewhere between the engaging contact surfaces. The leaf spring M, which I utilize in this embodiment of my invention, is particularly adapted for securing this result sinceit acts as a member having its fulcrum at the point 59. In order to secure the maximum contact pressure the spring M is assembled under considerable initial tension.

To open the contacts manually the operating handle i3 is moved in a clockwise direction from the position shown in Fig. 9; the line of action of the overcenter springs i3 is thereby brought across the center line of the link 65 and upon further movement causes a collapse of the toggle in the direction of trip device I5. The interconnecting frames 25 of the switch members i are immediately caused to move in a clockwise direction about their pivot pins 53. This movement, however, does not immediately effect the moving contact members 2i because of the time required to take up the loss in motion resulting from the slots 29 and their cooperating pins 2?. Thus, no contact separation begins to occur until the switch members have been moved to the position shown in Fig. 3 and thepin 21 has engaged the bottom of the slot 29. The contact pressure remains substantially constant due to the initial tensioning of the leaf spring M, and considerable kinetic energy is acquired by the moving switch member frames prior to the beginning of the actual contact separation. Immediately following the engagement of the pins 2? with the bottom of the slots 29 the contact members 2| are lifted and caused to rotate about the arcing surfaces 39 of the auxiliary contacts is, the entire biasing action of the spring 68 aiding this movement. The result is an immediate separation of the main current-carrying surfaces 33 and 35 and due to the blow action of the accumulated kinetic energy in the moving switch member frames, any tendency of the contacts to weld together is readily overcome. Continued movement of the switch members then results in a separation of the arcing surfaces and the establishment of the arc therebetween.

The above described method of supporting the moving contact member overcomes most of the diiliculties which were experienced with the previously known structures of this same general type. Heretofore, it has been customary to supply a rigid contact member having two or more contact surfaces at one end, a journal portion midway of the ends, and a portion for engaging the contact pressure securing spring at the other end, thecontact member being rigidly pivoted on the frame of the moving switch member. With this form of construction, it is possible to have only the main contacts in engagement when in the fully closed position, it being impossible to accurately divide the forceof the contact pressure securing spring between the two contact surfaces. Thus, the sequence of the opening operation was as follows: the initial rotation of the frame caused the arcing contact surfaces to engage;

then the raising of the pivot pin lifted the main contact surfaces, and finally the arcing contac surfaces disengaged.

To secure satisfactory operation of this structure. it was necessary that the biasing spring be capable of rotating the moving contact member sufllciently rapid to overcome the separating movement resulting from the rotation of the switch member frame, the problem being further complicated by the fact that the arcing surfaces tended to separate more rapidly than the main current carrying surfaces (being farther from the pivot point of the frame). The obvious result was that the arc was frequently established between the main current carrying surfaces which is, of course, a very undesirable condition.

The structure of my invention, however, permits both the arcing and the main contact surfaces to engage at all times, it permits an accurate division of the contact pressure securing force between the two sets of contact surfaces; and, through the lost motion feature, it makes possible the opening of the contacts in a predetermined sequence without danger of the contacts welding together. The magnetic feature of the device further aids in securing the desired sequence of operation because it provides a force, substantially proportional to the magnitude of the circuit current for biasing the moving contact member about its pivot point and thus increasing the pressure between the engaging arcing surfaces. The net result is the securing of a contact structure which is incapable of welding together, and which operates in such manner that the arc is never established between the current carrying surfaces.

In many installations it will be desirable to provide some arc-extinguishing apparatus to be used in conjunction with this embodiment of my invention. This is not, however, a necessary part of my invention and no such structure has been disclosed herein.

When the circuit breaker is in the closed position and an overload or short circuit condition occurs in the circuit controlled by any one of the poles on the breaker the electro-responsive trip device i5 acts to release the latch 88 and permit its movement in a clockwise direction about the pin 99, a considerable biasing force being transmitted to the latch 89 through the portion 87 of the trigger 59. The immediate result is the re= lease of the trigger ea, permitting it to rotate in a counterclockwise direction about its pivot pin 83 'under the biasing action of the over-center springs 18.

The rotation of the trigger 89 causes the portion Hi to engage the knee pivot pin 75 and start it in motion toward the collapsed open position. At thesame time, it moves the pivot pin ti on the upper end of the link 65 in such a direction as to bring the center line of the operating springs 13 to the right of the center line of the toggle link 65. The combination of this initial movement of the knee pivot pin and the changing of the central line of the toggle causes an almost immediate opening of the breaker in exactly the same manner as described for manual operation. The various moving parts take the position shown in Fig. 11; it will be noted that the counter-clock wise movement of the trigger 69 has been limited by the engagement of the portion I I5 with the projection 93 and that the operating handle has taken a position midway between the open and closed positions, due to the engagement of the downwardly extending member ill with the end {it of the trigger S5. The operating handle is held in this position, because the line of action of the over-center springs 13 falls slightly to the right of the bearing supporting the operating member ll, thus exerting a component of force biasing the operating handle l3 clockwise into engagement with the trigger. This arrangement provides a very satisfactory means for indicating when the circuit breaker has been opened as a result of an abnormal electrical condition in the circuit controlled by any one of the poles of the 89, thereby causing the latch to move laterally.

toward the base of the trip device IS, the lateral movement being made possible by the slots I03.

As soon as the surface l2! clears the over-hanging end I05 the latch snaps back into the-latched position, due to the biasing action of the spring HF which not only biases the latch counter-clockwise about its pivot but also biases it away from the base 16 of the trip device. The various parts of the mechanism are thus restored to the position shown in Fig. 10, and the contacts may be 35 to the factthat once the knee of the toggle linkclosed manually exactly as pointed out above.

The mechanism is trip-free of the handle, due

age-has been set in motion it is impossible to prevent the completion of the opening or closing operations by holding the operating handle or by moving it in the opposite direction. Similarly,

upon the occurrence of an overload and the operation of the trip device, the contacts move to the open position regardless'of whether the handle is held in the closed position or not. This feature is of considerable value from the safety viewpoint and adds much to the dependability ofoperation in a circuit breaker. Should an attempt be made to close the breaker against an overload or against a short-circuit condition, the latch 89 will be released after a predetermined time delay or instantaneously, depending upon the magnitude of the overload, exactly as described before. The trigger will also be released and will cause the breaker to open independently of the position of the operating handle.

It will thus be seen that I have disclosed an improved circuit breaker operating mechanism and contact structure which includes a lost motion connection-between the moving contact member and the frame of the switch member, in order to secure a self -aligning abutting contact that shall not weld fast during its operation. In addition, I have disclosed an improved arrangement for the moving contact and the cont-act pressure securing spring of thev moving switch member of a circuit breaker in order to secure a predetermined sequence of contact separation during the opening operation, and I have provided means particuiarly adapted for use with my improved method of contact support for augmenting the contact pressure with a force substantially proportional to the current being carried at any particular instant.

While in accordance with the patent statutes I have given the foregoing details of a practical embodiment of my invention, it is to be understood that many of these are merely illustrative and that variations of their precise form will be desirable in some applications. I desire, there- 5 fore, that the language of the accompanying claims be accorded the broadest reasonable consideration and that my invention be limited only by what is explicitly stated in the claims and by the prior art.

I claim as my invention: l

1. In a circuit interrupter, a stationary contact means, and a movable switch member for opening and closing the circuit, said switch member including a frame having at least a portion thereof of magnetic material, a contact member supported on said frame and having a main contact portion and an auxiliary contact portion, spring means for biasing said contact member toward said stationary contact means, the line of action :0 of said spring biasing means falling between said main and said auxiliary contact portions, and magnetic means, which includes said portion of said frame which is of magnetic material, for augmenting the biasing action of said spring means.

2. In a circuit interrupter, a pair of relatively movable contact means for opening and closing the circuit, one of said contact means including a contact member having two contact portions, spring means for biasing said contact member toward said other contact means, the line of action of said spring means being between said contact members, and support means engaging said contact member through a lost motion connection, said support means including magnetic means for producing a force, adapted to augment said spring biasing means, that is substantially proportional to the current flowing through the associated contact member.

3. In a circuit interrupter, a stationary con- 40 tact assemblage, and a movable switch member for opening and closing the circuit, said switch member including a frame having at least a portion thereof of magnetic material, a contact member having a main contact portion and an auxiliary contact portion, resilient means for supplying a force biasing said contact member toward said stationary contact assemblage, the line of action of said force falling between said contact portions, means for causing said contact member to engage said frame through a floating connection when said interrupter is in the fully closed position, and magnetic means, including said portion of magnetic material for supplying a biasing force to said contact member, which force augments said resilient biasing means.

4. In a circuit interrupter, a stationary contact assemblage, and a movable switch member for opening and closing the circuit, said switch member including a frame, a contact member having at least two contact portions for engaging cooperating contact portions forming a part of said stationary contact assemblage, spring means, the line of action of which falls between said contact portions, for biasing said contact member toward said stationary contact assemblage, said frame being free to move independently of said contact member during a portion of the opening operation of said interrupter, and magnetic means for biasing said frame toward the open circuit position during the circuit opening operation in order to cause the contact portions of said contact member to disengage the said cooperating contact portion in a predetermined sequence, the reaction forces produced by said magnetic means :6

increasing the force biasing said cooperating contact portions toward each other when said interrupter is in the closed circuit position.

5. In a circuit interrupter, a stationary contact means, and a movable switch member for opening and closing the circuit, said switch member including a frame, means of magnetic material forming a part of said frame, a contact member, and means for supporting said contact member on said frame through a lost motion connection, said contact member having a conducting means afiixed thereto, said conducting means being adapted to extend along, and to be attracted to, said means of magnetic material forming a part of said frame in order to bias said contact member toward said stationary contact means when said interrupter is in the closed circuit position.

6. In a circuit interrupter, a stationary contact means, and a movable switch member for opening.

and closing the circuit, said switch member including a substantially channel-shaped frame of magnetic material, and a contact member pivotally supported on a pin which extends through slotted openings in the sides of said channelshaped frame, said slotted openings forming a lost motion connection between said contact member and said frame, said contact member having conducting means affixed thereto, said conducting means extending along said magnetic portion of said frame and being adapted to be attracted therett? during the operation of said interrupter in order to bias said contact member toward said stationary contact means.

7. In a circuit interrupter, a stationary contact means, and a movable switch member for opening and closing the circuit, said switch member including a substantially channel-shaped frame that is pivotally supported at one end, a contact member, having at least two contact portions, pivotally supported on said channel shaped frame through a lost motion connection which comprises a pin that extends through opposed slotted openings in the opposed sides of said frame adjacent the unpivoted end thereof, and spring means, the line of action of which falls between said contact portions, for biasing said contact member toward said stationary contact means.

8. In a circuit interrupter; a pair of relatively movable contact means, each of which includes a pair of contact surfaces, for opening and closing the circuit; and actuating means for causing said contact means to be moved into and out of engagement with each other; said actuating means including a frame member upon which one of said contact means is pivotally supported, both of the contact surfaces thereof being positioned to one side of the point where said contact means is pivotally supported on said frame member, and spring means, the line of action of which falls between said pair of contact surfaces for resiliently biasing said contact means toward each other when said interrupter is in the closed circuit position.

9. In a circuit interrupter; a stationary con tact means having a pair of contact surfaces; a movable contact member likewise having a pair of contact surfaces for cooperating therewith to open and to close the circuit; and actuating means for moving said contact member into and out of engagement with said stationary contact means; said actuating means including a frame member, a pivot pin for pivotally supporting said contact member on said frame member, the axis of said pivot pin being positioned to one side of said pair of contact surfaces, spring means, the line of action of which falls between said pair of contact surfaces, for resiliently biasing the cooperating contact surfaces toward each other when said interrupter is in the closed circuit position, and a lost motion connection intermediate said frame and said support pin.

10. In a circuit interrupter; a stationary contact means having 'a pair of contact surfaces; a movable contact member likewise having a pair 10 of contact surfaces for cooperating therewith to open and to close the circuit; and actuating means for moving said contact member into and out of engagement with said stationary contact means; said actuating means including a channel shaped frame member having slots in the opposed side portions thereof, a pivot pin adapted to engage said opposed slots to pivotally support said contact member on said frame member, the axis of said pivot pin being positioned to one 20 side of said pair of contact surfaces, and spring means, the line of action of which falls between said pair of contact surfaces, for resiliently biasing the cooperating contact surfaces toward each other when said interrupter is in the closed cirg5 cuit position; said opposed slots creating a lost motion connection intermediate said frame and said contact member supported thereon.

11. In a circuit interrupter; a stationary contact means having a pair of contact surfaces; a 30 movable contact member likewise having a pair of contact surfaces for cooperating therewith to open and to close the circuit; and actuating means for moving said contact member into and out of engagement with said stationary contact 35 means; said actuating means including a channel shaped frame member having slots in the opposed side portions thereof and having at least a portion thereof of magnetic material, a pivot pin adapted to engage said opposed slots to pivgo otally support said contact member on said frame member, the axis of said pivot pinbeing positioned to one side of said pair of contact surfaces, spring means, the line of action of which falls between said pair of contact surfaces, for s5 resiliently biasing the cooperating contact surfaces toward each other when said interrupter is in the closed circuit position, and magnetic means including said portion of magnetic material for augmenting the action of said spring so means by a force substantially proportional to the current flowing through said cooperating contact surfaces, said opposed slots creating a lost motion connection intermediate said frame and said contact member supported thereon. 5E

12. In a circuit interrupter, a stationary contact member, and a switch member for cooperating therewith to open and to close the circuit, said switch member including a substantially channel shaped frame, means for supporting said m frame, including a pin which extends through aligned openings in the opposed side portions of said frame, a contact member supported on said frame, and a spring means for resiliently biasing said contact member toward said stationary con as tact member, said spring means comprising a flat leaf spring, one end of which is provided with a portion of substantially the same outline as said pin, said fiat spring being disposed within and being adapted to extend along said channel 70 shaped frame, said end having substantially the same outline as said pin engaging said pin to prevent said spring from moving relative to said frame, the other end of said spring engaging said contact means, and the central portion of said ta spring engaging the central portion of said channel shaped frame.

13. In a circuit interrupter, a stationary contact member, and a switch member for cooperj ating therewith to open and to close the circuit,

said switch member including a substantially channel shaped frame, means for supporting said -rame, adjacent one of its ends, including a pivot pin which extends through aligned openings in the opposed side portions of said frame, a contact member pivotally supported on the other end of said frame, and a spring means for resiliently biasing said contact member toward said stationary contact member, said spring means comprising a fiat leaf spring, one end of which is provided with a portion of substantially the same outline as said pin, said flat spring being disposed within and being adapted to extend along said channel shaped frame, said end having substantialiy the same outline as said pin engaging said pin to prevent said spring from moving relative to said frame, the other end of said spring engaging said contact means, and the central por= tion of said spring engaging the central portion of said channel shaped frame, the point at which said contact member is pivotally supported on said frame being positioned intermediate the point at which said spring engages said contact member and the point at which said spring engages the central portion of said frame.

BENJAIVHN P. BAKER.

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