US2218374A - Circuit breaker - Google Patents

Description

Oct. 15, 41940. w. A, ATWOOD 2,218,374

CIRCUIT BREKBR l Qrignal Filed DSC. 17, 1936 3 Sheets-Sheet l In ventor:

Winfield A. Atwood,

l-ls Attorneu.

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CIRCUIT BREAKBR original Filed Dec. 17, 1956 3 Sheets-Sheet 2V &\\\\\\\\\\\\\\\\\\\\\\\"&\\\\\\\\\\\\ Inventor: Winfield A. Atwood,

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oct? 15, 1940. w A, ATWOOD 2,218,374

C IRCU-I T BREAKBR original Filed Dec, 17, 1936 3 Sheets-Sheet 3 Inventor:

Winfield A. Atwood.

His Attorng.

Patented Oct. 15, 1940 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Winfield A. Atwood, naam-ra., signor to General Electric Company, a corporation of New York 2 Claims.

My invention relates to circuit breakers, more particularly to combined automatic and manual circuit breakersI in which the circuit controlling contacts are manually operable between open and closed circuit positions and are automatically operable to open circuit position upon the occurrence of predetermined current conditions, and has for an object the provision of a circuit breaker of this character which is simple and reliable in its operation and which is inexpensive to construct.

This application is a division of my copending application, Serial Number 116,413, led December 17, 1936, for Circuit breakers, now Patent No. 2,169,085, issued August 8, 1939.

Various circuit breakers of this character have heretofore been provided, many of which are to a large extent satisfactory for the purposes for which they are designed. Such circuit breakers have found considerable application in the control of distribution and feeder circuits and it is highly desirable in such cases that the circuit breakers not only be capable of handling large currents, but also be extremely compact and rugged in their construction. Something is yet to be desired, therefore, in circuit breakers of this character and it is a further object of my invention to provide a simple and reliable circuit breaker of this type which is of rugged and compact construction.

In carrying out my invention in gone form, I provide a circuit breaker comprising a rotatable shaft for controlling the circuit breaker contacts, the shaft having noncircular ends arranged respectively to engage corresponding noncircular apertures in a pair of crank members, together with manually and automatically operable means for rotating the crank members to cause movement of the circuit controlling contacts between open and closed circuit positions. More specifically, I provide a multiple pole circuit breaker in which a plurality of rotatable axially spaced shafts are provided for operating a plurality of switch members each of the shafts having noncircular ends, the shafts being interconnected by insulating crank members disposed in the spaces between the shafts with the ends of the shafts extending into noncircular recesses in the opposite faces of the crank members.

The operating mechanism for the crank members includes toggle means manually operable by suitable overcenter spring means to rotate the cranks and a. tripping member biased by a tripping spring to operate the toggle means independently of the overcenter spring means, The

tional view .of a circuit breaker embodying my invention; Fig. 2 is a plan view, partly in section,

Y of the circuitrbreaker shown in Fig. l with certain parts broken away, more clearly to illustrate the constructional details; Figs. 3 and 4 are fragmentary enlarged views similar to Fig. 1 showing the circuit breaker in dierent operating positions; and Fig. 5 is a detail view in exploded perspective of certain operating elements of the circuit breaker.

Referring now to the drawings, I have shown my invention in one form as applied to a circuit breaker comprising a base I0 formed of molded insulating material and having a plurality of walls Ilia which cooperate with similar walls I2 in a cover member II for separating the individual poles of the circuit breaker, the lefthand end of the cover II being open, as shown in Fig. 1. Disposed on the base I0 adjacent the open end of the cover II is a sub-base I3 which supports the tripping unit to be described hereinafter and which is provided with a cover member I4, the sub-base I3 and the cover member I4 serving to close the open end of the cover II. Mounted on the base I0 between the outer walls of the cover I I and the inner walls I2 thereof are a plurality of compression chamber type interrupter units I5 and an operating mechanism I6 which is disposed between the trip unit carried by the sub-base I3 and the interrupter unit for the middle pole of the circuit breaker.

These interrupter units I5 form no part of my invention and are particularly described and claimed in a copending application of D. W. Ver Planck and J. W. Seaman, Serial No. 116,384, filed December 17, 1936, now Patent No. 2,133,- 158, issued October 11, 1938, which application is assigned to the same assignee as the present invention.

Since each of the interrupter units I5 is identical in construction, only one of these units will\ as comprising walls of pressure resistant material arranged to form a compression chamber, the wall of the interrupter unit adjacent the operating mechanism comprising a plurality of supporting members I1 and I8 which are formed of conducting material, preferably die-cast aluminum. As shown best in Fig. 5, these supporting members I1 and I8 include upstanding portions which are provided with transverse grooves I9 and 20 respectively, the supporting member I1 being provided with an aperture 2| which intersects the groove I9. When the members I1 and I8 are secured together in face to face relation, for example, by means of suitable dowel pins 22, and by suitable screws 23 (Fig. 2), the cooperating grooves I9 and 20 form substantially cylindrical bearings in which a shaft 24 (Fig. 5) is journaled, the ends of the shaft being noncircular or square, as shown, and extending outwardly beyond the edges of the members I1 and As shown, the bearing portions of the shaft 24 are provided with suitable grooves 25 for accommodating suitable packing material in order gastightly to seal the compression chamber and the compression chamber is completed by means of a cup-shaped member 26, the open end of which is secured to the supporting member I1. Secured to the shaft 24 intermediate the bearing portions is a switch member 21 which extends through the aperture 2l in the supporting member I1 and carries a movable contact 28 which is arranged to engage a stationary contact 29 supported within the compression chamber on an arcing horn 38 which is in turn supported on a conducting stud 3I which extends through and is insulated from the horizontally extending portionof the support I1.

Thus, it will be seen that the circuit through each pole of the circuit breaker extends (Fig. 1) from a terminal member 32 adjacent the righthand end of the base I0 by way of a conductor 33, the conducting stud 3I, the arcing horn 30, the stationary and movable contacts 29 and 28, and through a flexible conductor 34, one end of which is connected to the contact 28 and the other end of which is connected to the conducting supporting member I8. The supporting member I8 thus forms a portion of the electrical circuit, which circuit extends from the supporting member I8 through the trip unit by way of suitable conductors 35 and 36 to a terminal member 31 disposed on the left-hand end of the base I8.

As shown, the three interrupter units I5 are disposed in side by side relation so that the respective shafts 24 are arranged in axially spaced relation, and as shown best in Fig. 5, these axially spaced shafts are mechanically interconnected and electrically insulated from each other by means of a pair of insulating operating members, shown as crank disks 38 which are disposed in the spaces between the shafts 24. Each of these crank members or disks 38 is provided with noncircular recesses or apertures 39 in the opposite faces thereof into which the adjacent noncircular ends of the shafts 24 extend, the respective opposite ends of the shaft 24 for the center interrupting unit extending into the apertures 39 in the inner faces of the disks 38 and the inner ends of the shafts 24 for each of the outer interrupting units extending-into the apertures 39-in the outer faces of the disks 38.

The supporting member I8 for the center pole of the circuit breaker differs somewhat from the supporting members I8 `for the outer poles 0f the circuit breaker in that it is provided adjacent its left-hand end with an upstanding portion 48 so as to form a substantially U-shaped frame upon which the operating mechanism of the circuit breaker is supported. This operating mechanism, as shown, comprises an inverted U-shaped operating member 4I which straddles the supporting member I8, the lower ends of the legs of the U-shaped member being pivotally supported on pins 42 which extend outwardly from the base portion of the U-shaped supporting member I8 and the upper yoke portion of the member 4I carries an operating member or handle 43 which is formed of suitable insulating material and which extends through an aperture 44 in the circuit breaker cover I I.

Intermediate the ends of the legs, the U-shaped operating member 4I is provided with a pair of inwardly extending pins 45 which support the respective adjacent ends of a pair of overcenter springs 46, the opposite ends of which are secured to suitable outwardly extending pins 41 carried by the side plates of a U-shaped toggle member 48. As shown, this toggle member comprises a pair of side plates connected together by a cross member 49 and is pivotally mounted on a pin 58 (Figs. l, 3, and 4) which extends through suitable apertures 5I in the toggle member 48 and through an aperture 52 in the portion 40 of the supporting member I8.

This toggle member 48, as shown best in Fig. 5, is likewise provided with a pair of outwardly extending pins 53 which are pivotally engaged by a pair of parallel links 54 which constitute the other link of the toggle and which are secured to a shaft or rod 55 which extends between the-crank members 38, the opposite ends of the shaft 55 being disposed in suitable apertures 56 (see Fig. 5) in the crank members. It will thus be seen that the crank members 38 are connected together for simultaneous operation to actuate the switch member 21 between its open and closed circuit positions in response to movement of the handle 43.

In Fig. 1, the handle 43 is shown in its closed circuit position and it will be observed that the overcenter springs 46 bias the toggle members 48 and 54 to their made position which corresponds to the closed circuit positions of the switch members 21. In order manually to operate the switch members 21 to their open circuit positions, it is necessary only to move the handle 43 from the position shown in Fig. 1 to the position shown in Fig. 3, the consequent rotation of the operating member 4I about its pivot 42, thereby carrying the left-hand ends of the over-center springs 48 downwardly across the pivot pins 58 oi' the toggle link 48 so as to reverse the bias exerted by the overcenter springs on the toggle links.

As soon as the overcenter springs 46 pass overcenter relative to the pivot pins 58, the toggle link 48 will be rotated in a clockwise direction about the pivot 50 from the position shown in Fig. 1 to the position shown in Fig. 3 so as to break the toggle and rotate the cranks 38, the shafts 24 and the switch members 21 to the open circuit position shown in Fig. 3. Obviously, the circuit breaker may be reclosed by returning the handle 43 toward the position shown in Fig. 1 so as to move the overcenter springs 48 upwardly across the pivot pin 50 and again reverse the bias on the toggle link 48.

During operation of circuit breakers of this type, it is sometimes found that conditions may arise in which the circuit controlling contacts may partially weld or stick and accordingly the overcenter springs may not be sumciently strong to eiect opening movement of the circuit controlling contacts in response to movement of the operating handle. In order to ensure that the contacts will be positively opened whenever the operating handle is moved to its open circuit position, I provide a pair of links 55a which are connected to the shaft l55 and provided with elongated slots into which extend suitable pins 56a carried by the legs of the U-shaped operating member 4I. It will be apparent that if the cranks 38 are not operated in a counter-clockwise direction-by the overcenter springs and the toggle means when the handle 43 is moved in a counter-clockwise direction from the closed circuit position shown in Fig. 1, the pins 56a will engage the left-hand ends of the slots in the links 55a so as positively to move the cranks 38 in a counter-clockwise direction. As soon as the cranks 38 start to move in this direction, the overcenter springs 46 will of course be effective through the toggle links 48 and 54 to complete the movement of the cranks to their open circuit position.

In addition to the manual operating means just described, means are provided for automatically operating the switch members 21 to their open circuit positions independently of the handle 43 upon the occurrence of predetermined current conditions. This automatic operating means includes a tripping member 51 which, as shown in Fig. 5, comprises a pair of spaced apart plates connected together adjacent their opposite ends by suitable pins 56 and 59 and provided with elongated slots 6D which movably support the opposite ends of a pin 6I to which is secured one end of a tripping spring 62, the opposite end of the spring 62 being securedto a ilnger 63 formed integrally with the supporting member I8. The tripping member 51 is rotatably supported on a pin 64 which extends through an aperture 65 in the portion 40 of the supporting member I8, the extending end of the pin 64 providing stops for the toggle member 48 (Fig. 1). It will be observed that the slots 60 extend substantially radially from the pivot pin 64 for a purpose which will be more fully described hereinafter.

Normally, the tripping member 51 is restrained against the bias of the tripping spring 62 by a latch member 66 which is pivotally mounted on a shaft 61 extending outwardly from the portion 40 of the supporting frame I8, a torsion spring 68 which surrounds the shaft 61 being provided for biasing the latch 66 to the position shown best in Figs. 1 and 3, in which position one side of the latch 66 is engaged by a pin 69 which extends outwardly from the tripping member 51. In this position, the lower end of the latch 66 is disposed in the pathof movement of a roller 10 which extends outwardly from the tripping member 51 adjacent the pin 69 so as to prevent movement of the tripping member 51 from the position shown in Figs. 1 and 3.

Adjacent its other end, the tripping member 51 carries a-roller 1I which is supported on the pin 59 and which is arranged to engage the cross portion 49 of the toggle member 48 so as to operate the'toggle member 48 about its pivot pin 50 in a clockwise direction against the force exerted by the overcenter springs 46 to break the toggleand open the circuit breaker contacts whenever the tripping member 51 is released for movement in accordance with the bias of the tripping spring 62. It will be observed that with the tripping member 51 restrained in the positions shown in Figs. 1 and 3, the pin 6I, to which is connected the tripping spring 62, engages the innermost ends of the slots 60 and accordingly the force of the tripping spring 62 is applied to the tripping member 51 to produce a rotating moment through a minimumlever arm. As soon as the tripping member 51 is released for movement in a clockwise direction about its pivot to the position shown in Fig. 4, the pin 6I moves along the slots 60 and comes to rest in the outermost ends of the slots, thus automatically increasing the effective lever arm through which the force of the spring 62 is applied to the tripping member 51. By reason of this arrangement, I am enabled to obtain a minimum latching force while at the same time I obtain a maximum tripping force.

It will be apparent that as the tripping member 51 rotates the toggle link 48 from the closed circuit position shown in Fig. 1 to the open circuit position shoWn in Fig. 4, the right-hand ends of the overcenter springs 46 will be carried overcenter relative to the pivot pins 42 of the U- shaped operating member 4I and accordingly, the bias exerted on the operating member 4I will be reversed and accordingly the handle 43 will be operated in a counterclockwise direction from the closed circuit position shown in Fig. 1. As shown, the operating member 4I is provided adjacent its upper end with a transversely extending roller 12 which is disposed to engage the tripping member 51 so as to arrest the movement of the operating handle 43 in the mid-position shown in Fig. 4. Likewise, it will be observed that movement of the tripping member 51 and the toggle link 48 in a clockwise direction about their pivots is limited by engagement of the cross portion 49 of the toggle link 48 with the upstanding portion 40 of the U-shaped frame I 8.l

In order to reclose the circuit breaker after automatic operation to the open circuit position, it is only necessary to move the operating handle 43 in a counterclockwise direction from the position shown in Fig. 4 to the open circuit position shown in Fig. 3. As the operating handle 43 is moved in this direction, the roller 12 carried by the operating member 4I rotates the tripping member 51 in a counterclockwise direction about its pivot to the position shown in Fig. 3 and as soon as the roller 10 passes below the end of the latch 66, the spring 68 rotates the latch from the position shown in Fig. 4 to the latching position shown in Fig. 3, whereupon the tripping member 51 is again restrained against movement in accordance with the bias of the tripping spring 62. The circuit breaker may now be closed by moving the handle from the position shown in Fig. 3 to the position shown in Fig. 1, asdescribed above.

Although any suitable current responsive means may be provided for operating latch 66 from its latching position to release the tripping member 51, I have shown for purposes of illustration a shock-proof electromagnetic trip unit which embodies certain novel features described and claimedin Patent No. 2,067,792 to Joseph W. Seaman, issued January 12, 1937, and in Patent No. 2,067,797 to Robert W. Smith, issued January 12, 1937.

As shown, this trip unit is mounted on the subbase I3 and comprises a pair of spaced apart frame plates 13 between the upper ends of which is pivotally supported a U-shaped releasing member, one leg of which comprises a striking portion 14 and the other leg of which comprises a latching portion 15 and a resetting portion 16.

This releasing member is normally biased for movement in a clockwise direction about its pivot pin 11 by a torsion spring 18 and is restrained against movement by engagement of the latching portion 15 with a trip shaft 19 which is jour- ,naled in the frame plates 13 and extends across the three poles of the circuit breaker. As shown best in Fig. 2, this shaft 19 is provided adjacent the middle pole of the circuit breaker with. a notch 8U and with an extending arm 8|, the opposite outer ends of the shaft 19 which extend over the outer poles of the circuit breaker being provided with operating arms 82 which are formed of insulating material. Likewise, the shaft 19 is provided with a biasing spring 83 which normally biases the trip shaft 1S to the position shown, in which position the latching portion 15 of the releasing member engages the periphery of the shaft adjacent the notch 80.

In order that the trip shaft 19 may be rotated in a clockwise direction, to release the latching portion 15 of the releasing member for movement through the notch 88, in response to predetermined current conditions in any one of the circuit breaker poles, the trip unit is provided with a plurality of electromagnetic devices, one of which is connected in each pole circuit of the circuit breaker, each of these electromagnetic devices being arranged to engage one of the operating arms 8| or 824 on the trip shaft 18. As is more fully described in the above-referred to Seaman application, each of the electromagnet devices comprises a magnetizable frame 8l which is provided with an energizing winding 85, one end of which is connected to the conductor 35 and the other end of which is connected to the conductor 36, and with a balanced armature 86 which is pivoted on the frame 84. This balanced armature 86 is provided with a shock-spring 81 of the type particularly described and claimed in the above-referred to Smith application and ,carries adjacent its upper end an adjustable member or screw 88 arranged to engage the associated operating arm 8| or 82 on the trip shaft 19 when the armature 86 is operated in a counterclockwise direction about its pivot. Normally the armature 86 is biased to the unattracted position shown by a spring (not shown), one end of which is connected to an adjustable member 89 carried by the upper end of the armature 86.

It will now be apparent that upon the occurrence of predetermined current conditions in any pole of the circuit breaker, one or more of the armatures 86 will be attracted upon a predetermined energization of the associated winding and the adjustable member 88 will engage the associated operating arm 8| or 82 on the trip shaft 19 so as to rotate the trip shaft in a clockwise direction and thereby release the latching portion 15 of Athe releasing members for movement through the notch 80. As soon as the latching portion of the releasing member is released for movement through the notch 80, the spring 18 rotates the releasing member in a clockwise direction about its pivot 11, whereupon the striking portion 14 of the releasing member strikes the upper end of the latch 66 a hammer blow and rotates the latch 66 in a clockwise direction about its pivot to release the tripping member 51 for operation in the man ner described above.

In addition to the functions hereinbefore described, the tripping member 51 also serves to reset the releasing member as the tripping-member moves to its tripping position and for this purpose the tripping member is provided with a roller which is arranged to engage the resetting portion 16 of the releasing member so as immediately to return the releasing member to its latched position shown in the drawings. As soon as the circuit breaker opens, the energizing windings 85 of the electromagnetic devices are de-energized and accordingly the armatures 86 immediately return to their biased position shown, whereupon the trip shaft 18 is rotated to its latching position by the spring 83 to re-engage the latchng portion 15 of the releasing member.

Thus, the releasing member of the trip unit is immediately reset and latched in its normal position and as soon as the operating handle 43 is actuated to reset the trip member 51, the roller 90 moves out of engagement with the resetting portion '.'6 of the releasing member so that the releasing member is free to move immediately to its releasing position if an overload condition still exists when the circuit breaker is recloscd.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

l. A multiple pole electric circuit breaker comprising a plurality of single pole circuit interrupting units having substantially the same construction, each of said units comprising a single pole switch member, a gas-tight enclosing casing for said switch member formed by walls of pressure resistant material, and a shaft journaled in said walls of said casing for operating said switch member between open and closed circuit positions, and journals for said shaft mounted in said walls and forming gas-tight joints with said shaft means for supporting said interrupting units in side by side relation with said shafts in alignment with each other and with adjacent ends of said shafts in axially spaced relation with each other, the ends of each of said shafts projecting outward from each side of its said casing so that said units are interchangeably mountable in said side by side relation, means for interconnecting the adjacent ends of said shafts comprising a crank member formed of electrically insulating mai terial mounted between said adjacent ends and provided with recesses in opposite faces in which said adjacent ends of said shafts extend and are thereby secured for simultaneous rotary movement by said crank, and manually operable means engaging said crank for operating said crank to rotate said shafts and thereby operate said switch members simultaneously between open and closed circuit positions.

2. A multiple pole electric circuit breaker comprising at least three 'single pole circuit interrupting units having substantially the same construction, each of said units comprising a single pole switch member, a gas-tight enclosing casing for said switch member formed of walls of pressure resistant material, and a shaft journaled in said walls of said casing for operating said switch member between open and closed circuit positions, journals for said shaft in said walls, packing means in said journals gas tightly sealing said journals around said shaft so as to gas tightly seal said enclosing casing, means for supporting said interrupting units in side by side relation with said shafts in alignment with one another and with adjacent ends of said shafts in axially spaced relation with each other, the ends of each of said shafts being non-circular and extending outward from opposite sides of its said casing so Y that said units are interchangeably mountable in said side by side relation, means for interconnecting the adjacent ends of said shafts comprising crank members formed of electrically insulating material mounted betweenvsaid adjacent ends and provided with non-circular recesses in 10 opposite faces in which said non-circular adjacent ends of said shafts extend and are thereby secured for simultaneous rotary movement by said cranks, one of said interrupting units having a crank member on each side thereof, and manually operable means engaging said cranks for operating said cranks simultaneously to rotate said shafts and thereby operate said switch members simultaneously between open and closed circuit positions.

WINFIELD A. ATWOOD.

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