US2229412A - Circuit breaker - Google Patents

Description

Jan. 21, 1941` o. s. .JENNINGs CIRCUIT BREAKER Original Filed Deo. 17, 1936 2 Sheets-Sheet 2 INVENTOR //i/e/'nn/'ng WITNESSES:

ATTORNE Patented `Ian. 21, 1941 y UNITED STATES PATENTl OFFICE CIRCUIT BREAKER Oliver S. Jennings, Pittsburgh, Pa., assigner' to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 17, 1936, Serial No. 116,325 Renewed April 25, 1940 40 Claims. (Cl. 200-116) My invention relates to circuit breakers in The novel features thatIconsider cha general, and more particularly to cir'cuit breakers of my invention are set forth in particular in the of the type used, for controlling lighting and appended-claims. The invention itself, however, moderate power industrial feeder circuits. both as to structure and operation, together witha A commercially successful circuit breaker for additional objects and advantages thereof, will 5 this type of service must satisfactorily meet very best be understood from the following detailed exacting requirements. Among other things the description of a specific embodiment thereof when breaker must have an eiiicient operating mecharead in connection with the accompanying drawnism which is manually operable to open and ingsin which:

l0 close the contacts of the breaker and which is Figure 1 is a top plan viewof a load center de- 10 automatically operable to open the contacts of vice having circuit breakers embodying the feathe breaker in response to predetermined overtures of my invention, the cover and operating load conditions. Thebreaker must be trip free handles having been removed to illustrate certain of the operating handle and should give a clearly features.

discernible indication of its tripped condition Fig. 2 is a vertical sectional View of one of the when opened in response to overload conditions. circuit breakers illustrated n Fig. 1 showing the Some means must also be provided for readily breaker in the closed circuit position and taken adjusting the trip characteristic of the breaker on the line II-II of Fig. 1.

. so that it can beused under varying load condi- Fig. 3 is a perspective view of one of the oper 2 tions. ating members of the circuit breaker.

As opposed to these operational requirements, a Fig. 4 is a vertical sectional view similar to commercially successful circuit breaker must be Fig. 2 showing the circuit breaker in the manu-- moderate in price, both because of the large ally opened position, and f number used in even a moderately sized building Fig. 5 is a vertical sectional view similar to i or factory, and because of the fact that eX- Fig. 2 showing the circuit breaker in the tripped 2i cessively costly breakers cannot be economically position. justined over the older butl less desirable fuse Referring to the drawings, the load Center or and switch arrangements. Y panel-board circuit breaker illustrated comprise Heretofore the manufacturers of these devices in general, a casing "l, `a removable cover 9, a pluhave endeavored to effect a compromise between rali'ty of load terminals IE, a common line termi- 3@ these coniiicting requirements by manufacturing nal means i3, a plurality of floating switch arms breakers as cheaply as possible consistent with I5 and individual operating means indicated good quality and ability to meet the exacting generally at Il for each of the switch arms.

operational requirements. The best of the prior The casing 'l is of molded insulating material h 3U art devices, however, was more costly than would and has a plurality of vertical partitions i9 3a be desired. formed integral therewith for dividing the casing It is accordingly the principal object of my ininto a plurality of longitudinal compartments 2i. vention to provideasimple, eiicient and inexpen- The casing is open at the top and at one end, sive circuit breaker which will satisfactorily meet and the edges of the side Walls and end wall 40 the above mentioned operational requirements. thereof are formed to provide a seat for the 40 .Another object of my invention is t0 provide cover 9. A removable end wall 23 of insulating an improved circuit breaker structure that is material is adapted to be slidably received in simpler and less expensive to manufacture than vertical grooves 25 formed in the side walls of the previously known devices of this type. the Acasing and in a recess 2l formed in the Another object of my invention is to provide an central partition l 9. The cover 9 is of insulatingV 55 improved circuit breaker structure that utilizes `amaterial and is provided at one end with a deconsiderably less number of parts than has herepending ange portion 29 fOr retaining the end tofore been considered necessary. wall 23 in operative position. The cover t may Another object of my invention is to provide a be secured to the casing l in any suitable simpler operating mechanism for a circuit manner. E@ breaker which requires fewer parts than similar A load terminal Il is provided for each of the devices heretofore known or used and which opercompartments. Each load terminal is formed of ates when the breaker is tripped to give a clearly a strip of conducting material preferably copper. discernible indication of `the tripped condition Each terminal strip 'I l is provided with a dependof the breaker. ing portion 3| adapted to seat in a recess provided ofi therefor in the base 1, and an upwardly projecting portion- 33. The upwardly projecting portion 33 is provided with a threaded opening 35 for threadedly receiving an adjustable latch piece 31. Each of the load terminals I-I is provided with a terminal screw 39 for connecting a load conductor to the terminal.

The common line terminal I3 is disposed at the opposite end of the casing from the load terminals II, and consists of a iiat plate of .conducting material provided with a plurality of spaced projections 4I constituting a plurality of stationary contacts one for each pole of the breaker. The conducting plate is secured by means of a clamping screw 43 to a boss 42 formed integral with the casing 1. One end 45 of the conducting plate I3 extends through an opening in a side wall of the casing 1 and provides a means for connecting the plate I3 to a line conductor.

A oating switch arm I5 is disposed in each compartment 2I. Each of the switch arms I5 is formed of bimetallic material, and one end 41 thereof is adapted to normally engage its corresponding adjustable latch piece 31. The other end of each switch arm I5 has a movable contact 49 secured thereto for engaging its corresponding stationary contact projection 4I. The side Walls of the casing 1 and each of the partitions I9 are provided with vertically disposed guide ribs 5I for guiding the switch arm I5 during movement of the same to open and closed circuit position.

Each of the switch arms is provided with an individual operating means comprising, in general, a spring 53, an operating member 55 and an operating handle 51. 'I'he spring 53 has its lower portion disposed' in a circular recess 59 provided in the base 1 and its upper end engages the under surface of the switch arm I5. The spring 53 biases the switch arm I5 to closed circuit position as shown in Fig. 2 and presses the contact 49 against its cooperating stationary contact projection 4I. The spring 53 also biases the end 41 of the switch arm against its latch piece 31. The operating member 55 is formed of any suitable material and is provided at its lower end with a reduced portion forming shoulders 62 and a projection 6I (Fig. 3) which is adapted to be received in a rectangular opening 53 provided in the switch arm I5 thus providing a pivotal coupling between the operating member 55 and the switch arm I5. The upper end of the operating member 55 is provided with a horizontally extending projection 65 and an olf-set vertical projection 61. Each of the operating members 55 is mounted for vertical sliding movement by means of vertical grooves 69 formed in the side Walls of the casing and in the sides of the partitions I9. The operating handle 51 for each switch arm is formed of molded insulating material and has a handle portion 1I, a cam projection 13 and a shoulder portion 15.' The operating member 51 also includes a pivot pin 11 secured to the handle 51 by means of its tight frictional engagement in the opening provided therefor in the handle 51. The pivot pin 'I1 is slightly longer than the width of the handle 51 and its projecting ends are adapted to be received in semi-circular recesses 19 formed in the side walls of the casing and sides of the partitions at the top of the vertical grooves 69. The semi-circular recesses 19 form bearings for the pins 11. 'I'he handle projection 1I of each handleis adapted to project through an opening 8l provided therefor in the cover 9. The edges of the cover 9 bounding the sides of placed in their recesses 59 and the switch arms I5 are then dropped into their compartments. The load terminals II and the stationary contact plate I3 are then mounted in position with the ends 41 of the switch arms I5 engaged under their latch pieces 31 and the movable contacts 49 under theirv corresponding stationary contact projections- 4I. The operating members 55 are then slid down into the vertical grooves 69 provided therefor, and the pivot pins 11 of the operating handles 51 are dropped into the semi-cir cular recesses 19 provided in the casing 1 and partitions I9. The end wall 23 is then slid into the grooves 25 provided therefor, and the cover 9 placed on the top of the casing and secured thereto. It will thus be seen that the specific structure of the circuit breaker permits the parts to be readily assembled, or disassembled for repair of` replacement purposes.

Each of the load terminals II is connected to its corresponding` switch arm I5 by means of a ilexible shunt conductor 83 in order to insure that no difference of potential exists between the load terminal and the switch arm, thus preventing arcing upon disengagement of the end 41 of the switch arm from the latch piece 31.

The circuit for each pole of the breaker extends from the load terminal II through the shunt .conductor 83 to the bimetallic switch arm I5,

movable contact 49 and stationary contact projection 4I of the terminal plate I3 to th-e line conductor.

The walls of the' chambered portion of the casing adjacent the movable contacts 49 and statween open and closed circuit position by the operating member 55l during manual operation of the breaker. It will also be noted that the compression spring 53 engages the bimetal switch arm I5 ata point adjacent the pivotal connection of the operating member 55 and the switch arm I5 and between said pivotal connection and the end 41 of the switch arm.

The operation of the circuit breaker is as follows: With the parts in the position shown in Fig. 2, let it be assumed that it is desired to open the circuit of one of the poles of the breaker. To open the circuit, the operating handle 51 is moved from the closed circuit position shown in Fig. 2 in a clockwise direction about its pivot axis 11 to the open circuit position shown in Fig. 4 in which the handle projection 1I engages the opposite edge of the opening 8| in the cover 9. Movement of the operating handle to its open circuit position causes the cam projection' 13 thereof to engage the horizontal projection 55 of the operating member 55 to move the operating member in a downward direction.

' Movement of the operating member 55 down.

wardly causes movement of the switch arm I5 in formed by the engagement of the end 41 thereof with the latch piece 31, to the open circuit position shown in Fig. 4. The downward movement of the switch arm I5 is limited by the engagement of the contact carrying end thereof with the bottom of a'recess 84 formed in the casing 1.'

When the handle 51 is in the open circuit position, the force exerted by the spring 53 is transmitted through the switch member 'I5 and the operating member 55 to restrain the operating handle in its open circuit position. I'he manual open .circuit position of the breaker is illustrated in Fig'. 4.

To close the circuit breaker, the operating handle 51 is moved from the open circuit position illustrated in Fig. 4 to the closed circuit position shown in Fig. 2. During this movement of the operating handle, the spring 53 moves the switch arm I5 to closed circuit position and causes the operating member 55 to move in an upward direction back to the position shown in Fig. 2. It will be noted that during manual opening and closing of the circuit breaker the switch arm I5 is moved about its normal pivot point formed by the engagement of the end 41 with the latch piece 31. In the closed circuit position the spring 53 biases the switch arm I5 toward its released position, but the arm I5 is restrained from moving to its released position by reason of the engagement of the end 41 of the arm with the latch piece 31.

If an overload of predetermined magnitude and duration occurs in the c ircuit controlled by the pole of the breaker, the passage of the overload current through the bimetallic switch arm -I5 heats the same and causes it to flex in a direction such that the end 41 disengages the latch piece 31. The switch arm I5 is then fre-e to move to its released positionirrespective of the position of the operating handle 51, and the spring 53 causes the switch arm I5 to rotate in a clockwise direction about a new pivot point, which is that formed by the point of engagement of the operating member 55 with the switch member I5. The clockwise rotation of the switch arm I5 to its released position about the new pivot point moves the contact carrying end of the switch arm to open circuit position as shown in Fig. 5. Following the release of the switch arm I5 during the tripping operation, the spring 53 also moves the operating member 55 in an upward direction which causes the oli-set projection 61 thereof to engage the shoulder 15 of the operating handle 51 to move the operating handle to an intermediate indicating position as shown in Fig. 5. Any further movement of the operating handle is prevented by reason of the engagement of the horizontal projection '65 with the cam projection 13. The operating means thus moves the operating handle- 51 to a clearly discernible indicating position to indicate that an overload has occurred on that particular pole of the circuit breaker and that the switch arm of said pole has been tripped to open circuit position.

To reset the switch arm after a tripping operation, the operating handle 51 is moved to the full open position during which the cam projection depresses the operating member 55 and rotates the switch arm in a counter-clockwise. direction about its contact carrying end until the end 41 reengages under the latch piece 31. 'I'he breaker pole may then be reclosed by moving the operating handle to the closed circuit position shown in Fig. 2. The operation of each pole of the circuit breaker is identical and hence the above description of the'operation of one pole will be suflcient.

It will be 'noted that the switch arm is trip free of the operating handle, that is it can move to open circuit position when tripped even though the operating handle is held in closed circuit position.

The trip characteristic of each pole of the circuit breaker may be adjusted by changing the position of the adjustable latch piece 31 to change the amount of overlap of the latch piece with respect to the end 41 of the switch arm. Increasing the amount of overlap requires a higher value of overload current for tripping the breaker, or increases the time interval on lower overloads between the occurrence of the overload and the release of the switch arm. It will be noted that the removably mounted end wall 23 permits easy access to be had to the adjustable latch pieces when adjustment of the trip characteristics of the breaker is desired.

The springs 53, in addition to biasing the switch arms I5 to closed circuit position and moving the switch arms to open circuit position, fol-` provide a definite contact pressure between the movable contacts 49 and the stationary contact projections 4 I It will thus be seen that I have provided an efficient and simple circuit breaker structure that utilizes a minimum number of parts and that can be manufactured at an extremely low cost.

While I have shown and described one embodiment of my invention, in accordance with the patent statutes, it is obvious that various changes in structure may be made in the structural details thereof without departing from the spirit of the invention. I desire, therefore, that the invention be limited only by the reasonable construction of the language ofthe appended claims and by the prior art.

I claim as my invention:

1. In a circuit interrupter, a switch arm including at least a portion of bimetallic material,

operating means for moving said switch arm to open and to closed circuit position, a xed support normally engaging said switch arm to hold the same during normal opening and closing operations thereof, said bimetallic portion being operable in response to predetermined conditions to disengage said switch arm from said support.

2. In a circuit interrupter, a contact controlling arm having at least a portion of bimetallic material, a xed support normally engaging said arm to form a pivot point for said arm, operating means for moving said arm about said pivot point to the open or to the closed circuit position, said bimetallic portion being operable in response to predetermined conditions to disengage said arm from said fixed support, and spring means for moving said arm to open circuit position upon disengagement of said arm from said support.

3. In a circuit interrupter, a floating switch arm having at least a portion of bimetallic material, a iixed support engaging one end of said arm for normally providing a pivot for said arm,

an operating means for moving said arm to an open and to a closed circuit position about said pivot point, said bimetallic portion being operable in response to predetermined conditions to effect disengagement of said end of said arm from said support, spring means engaging said arm for normally biasing said arm to closed circuit position, said spring means acting to move said switch arm to an open circuit position upon disengagement of said end of said arm from said support.

. lowing their release from the latch pieces, also 4. In a circuit .interrupter, aoating switch arm having at least la portion of bimetallic material, an adjustable support engaging one end of said arm for normally providing a pivot for said arm, an operating means for moving said arm to an open and to a closed circuit position about said pivot point, said bimetallic portion being operable in response to predetermined conditions to eiect disengagement of said end of said arm from said support, spring means engaging said arm for normally biasing said arm to closed circuit position, said spring means acting to move said switch arm to an open circuit position upon disengagement of said end of said arm from said support.

5. In a circuit interrupter, a switch arm of bimetallic material, a fixed support engaging one end of said arm for normally providing a pivot point for said arm, an operating member coupled to said arm for moving the same to an open and to a closed circuit position about said pivot point, spring means engaging said arm between said pivot point and said operating member for normally biasing said arm to closed circuit position, said arm being operable in response to predetermined conditions to disengage its end from said support so that said springA means moves said arm to an open circuit position.

6. In a circuit breaker, a switch arm having at least a portion of bilmetallic material, a support, a latch piece adjustably mounted on said support for overlapping engagement with one end of said switch arm for providing a normal pivot point for said arm, an operating member for moving said switch arm to open yand to closed circuit position, said bimetallic portion of said arm being operable in response to predetermined conditions to cause said end of said arm to disengage said latch piece.

7. In a circuit breaker', a switch arm having at least a portion of bimetallic material, a latch member engaging said arm for providing a pivot point for said arm, operating means for moving said arm about said pivot point to an open and to a closed circuit position, said bimetallic portion being operable in response to predetermined conditions to move said arm to disengage the same from said latch member, and adjusting means for predetermining the amount of movement of said arm necessary to disengage the same from said latch member.

8. In a circuit breaker, a switch arm of bimetallic material, a latch member engaging said arm to provide a pivot point for said arm, an operating means for moving said arm to an open and to a closed circuit position, said arm being operable in response to predetermined conditions to disengage said latch member to allow movement of said switch arm to an open circuit position.

9. In a circuit breaker, a switch arm having at least a portion of bimetallic material, a latch piece engaging one point of said arm to provide a pivot point for said arm, operating means for moving said arm about said pivot point to open and to closed circuit position, said bimetallic portion of said arm being operable in response to predetermined conditions to cause disengagement of said point from said latch piece, said operating means including means for automatically moving said switch arm' to open circuit position following the disengagement of said point from said latch piece.

10. In a circuit breaker, a switch arm having at least a portion of bimetallic material, a latch piece engaging said arm to provide a pivot point for said arm, actuating means including an operating handle for moving said switch arm about said pivot point to an open and to a closed circuit position, said bimetallic portion being operable in response to predetermined conditions to cause said arm to disengage said latch piece, said actuating means including means for automatically moving said swi'tch arm to open circuit poy sition following disengagement of said arm from said latch piece independently of the position of said handle.

1l. I n a circuit breaker, a switch arm having at least a portion of bimetallic material, a latch member normally engaging said arm to limit its movement to rotation about a pivot point, operating means for moving said arm about said pivot point to open and to closed circuit posi-- tion including a spring means acting when said arm is in closed circuit position to bias said arm to closed circuit position, said bimetallic portion being operable in response to predetermined conditions to cause said arm to disengage said latch member to allow said spring means to move said arm with its portion of bimetallic material to open circuit position.

. l2. In a circuit breaker, a contact operating arm having at least a portion of bimetallic material, a latch member normally engaging one point of said arm to form a pivot point for said arm, operating means including an operating member pivotally engaging a second point of said arm for moving said arm about said pivot point to open and to closed circuit position, said bimetallic portion being operable in response to predetermined conditions to effect disengagement of said anm from said latch member, said operating means including a means for moving said switch arm about said second point to open circuit position following disengagement of said armfrom said latch member.

13. In a circuit breaker, a contact operating arm of bimetallic material, a latch member normally engaging one point of said arm to provide a pivot point for said arm, operating means including an operating member pivotally engaging said arm at a second point for moving said arm about said pivot point to open and to closed circuit position, said arm being operable in response'to predetermined conditions to disengage said latch member, said operating means including a spring engaging said arm at a third point for normally biasing said ann to closed circuit lposition and for moving said arm to open circuit position following disengagement of said arm from said latch member.

14. In a circuit breaker, a contact controlling arm having a portion of bimetallic material, a

ing the release of said arm from said latch member.

15. In a circuit breaker, a. floating switch arm,

latch means normally engaged at one end of said arm to provide a pivot point for said arm, operltoanopen:n.ndtoaclosedcircuitposition,said

latch means including electro-responsive means for effecting release oi said end of said arm in response to predetermined conditions. said operating means including means for automatically movingsaidswitcharmtoopencircuitposition and said operating handle to 'an indicating position between its open and closed circuit positions following the release of said arm at said latch means.

16. In a circuit breaker,l a floating switch arm,

latch means normally engaged at one point oi' said arm to provide a pivot point for said arm. operating means for moving said arm about said pivot point to open and to closed circuit position including a pivoted operating handle movable to an open and to a closed circuit position to manu- Vally control-said switch arm, said latch means being operable in response to predetermined conditions to eiiect release of said arm, said operating means including means for automatically .moving said switch arm to open circuit positionv and said operating handle to an indicating position between its open and closed circuit positions following release of said arm.

17. In a circuit breaker, a iloating switch arm, a latch member normally engaging a first point of said arm to provide a pivot point for said arm. an operating member having one end engaging a second point of said arm, spring means engagv ing said arm between said mst and second points for normally biasing said arm and member to closed circuit position, a pivoted operating handle movable to an open circuit position to move said operating member and, through said operating member, said arm to open circuit position, said operating handle being movable to a closed circuit position to allow said spring means to move said operating member and arm to closed circuit position, electro-responsive means operable in response to predetermined conditions for effecting release ,of said arm from said latch member'to allow said spring means to move said arm about said second point to open circuit position, and means carried by said operating member for engaging and moving said handle to an intermediate indicating position between its open and closed circuit position following release of said arm from said latch member.

18. In a circuit breaker, a iloating'switch arm having at least a portion of bimetallic material, a latch member normally engaging a rst point of said arm to provide a pivot for said arm, an operating member pivotally engaging a second point of said arm, a spring engaging said arm between said iirst and second points for biasing said arm and operating member to closed circuit position'as long as said latch member engages said iirst point oi said arm, a pivoted operating handle having a shoulder and a cam portion, said operating handle being movable to an open circuit position to cause said cam portion to engage and move said operating member to open circuit position to move said switch arm to open circuit position, and being movable to elosed,

circuit position to allow said spring means -to move said arm and operating member to closed' circuit position, said bimetallic portion being operable in response to predetermined condition for eifecting release of said arm from said latch member to allow said spring to rotate said arm about said second point to open circuit position and to move said operating member toward said handle, and a proiectioncarried by said operat- '19. In a circuit breaker, a oating switch arm of bimetallic material, a latch member normally engaging one point of said arm to provide a pivotfor said arm, operating means including an `operating member engaging said arm at a second point and movable to an open and to a closed circuit positionV to eii'ect movement of said arm to open and to closed circuit position, saidarm 'being operable in response to predetermined conditions to disengage said latch member, said operating means including means for automatically moving said `arm to open circuit position -and said operating member to an indicating position following disengagement oi said arm from said latch member.

20. In a circuit interrupter, a circuit controlling member having at least a portion of bimetallic material. a fixed support normally engaging said member to form a pivot point for said member, operating means for moving said member to open and to closed circuit position to open and to close the circuit, said bimetallic portion being operable in response to predetermined conditions to disengage said member from said support to permit movement of the member to open circuit position.

21. In a circuit breaker, a switch member having at least a portion of bimetallic material, a iixed member engaging said switch member to provide a pivot for said switch member, operating means including an operating member for moving said switch member about said pivot to open and `to closed circuit position, said switch member being operable in response to predetermined conditions to disengage said iixed member and move to an 'open circuit position, said operating member being operable to reset said switch member in engagement with said fixed memben 22. In a circuit breaker, a switch member having at least a portion of bimetallic material, a

ilxed support normally engaging one part of said member to provide a pivot therefor, operating means including an operating member pivotally engaging a. second part of said member for moving said member about said first mentioned pivot to open and to closed circuit position, said switch member being operable in response to predetermined conditions to disengage said iixed support. said operating means including means for moving said switch member about the pivot formed by the engagement of the switch member with the operating member to an open circuit position following disengagement of the switch member from said support, said operating member being operable to reset said switch member A engagement with the xed support.

23. In a circuit breaker, a switch member hav- I arm having at least a portion of bimetallic material, a latch piece normally engaging one point of said arm to provide for rotation of said arm about a. pivot axis, operating means including an operating member pivotally engaging a second point of said arm for moving said arm about said pivot axis to open and to closed circuit position, said bimetallic portion being .operable in response to predetermined conditions to effect disengagement of said arm from said latch piece, said operating means including a means for moving said switch arm with its portion of bimetallic material about said second point to open circuit position following disengagement of said arm from said latch piece, irrespective of the position of said operating member.

25. In a circuit breaker, a iloating switch arm, latch means normally engaged at one end of said arm to provide a pivot point for said arm, operating means including an operating handle movable to an open and to a closed position toeffect movement of said switch arm about said pivot to an open and to a closed circuit position, said latch means including electro-responsive means for effecting release of said arm in response to predetermined conditions, said operating means including means for automatically moving said switch arm to an open circuit position irrespective of the position of said operating handle and for causing movement of said operating handle to an indicating position between its open and closed positions following the release of .said switch arm.

26. In a circuit breaker, a iloating switch arm, releasable and resettable latch means normally engaged at one point of said arm to provide a pivot point for said arm, operating means including apivoted operating handle movable to an open and to a closed circuit position for moving said switch arm about said pivot to an open and to a closed circuit position, said latch means being operable in response to predetermined conditions to effect release of said switch arm, said operating means being operable upon release of said switch arm to automatically move said switch arm to an open circuit position irrespective of 'the position of said operating handle and to cause movement of said operating handle to an indicating position between its open and closed circuit positions, and said operating means being operable to reset said latch means uponA movement of said operating handle to open circuit position.

27. In a circuit interrupter, a switch arm having thereon a contact portion and a latch portion movable relative 'to the contact portion in response to electrical conditions in the circuit, two pivot axes about which said switch arm is rotatable, manually engageable means operable to cause movement of said switch arm about one of said pivot axes with said contact portion and said latch portion moving as a unit between open and closed circuit positions, and resilient means acting on said switch arm to move it to open circuit position about the other of said pivot axes upon electrically responsive movement of said latch portion.

28. In a circuit interrupter, a switch arm having thereon a contact portion and a latch portion movable relative to the contact portion in response to electrical conditions in the` circuit. two pivot axes about which said switch arm is rotatable, manually engageable means operable to cause movement of said switch arm about one of said pivot .axes with said contact portion and said latch portion moving as a unit between open and1 closed circuit positions, resilient means acting on said switch arm to move it to open circuit position about the other of said pivot axes upon electrically responsive movement of said latch portion, and said manually engageable means being inoperative to rprevent said movement of the switch arm to open circuit position upon electrically responsive movement of the latch portion.

'29. In a circuit interrupter, a first contact portion, a switch arm having thereon a second contact portion and a latch portion movable relative to the second contact portion in response to electrical conditions in the circuit, 'two pivot axes about which said switch arm is rotatable, manually engageable means operable to cause movement of said switch arm about one of said pivot axes with said second contact portion and said latch portion moving as a unit between open and closed 'circuit positions, and resilient means applying a biasing force acting on said switch arm when in the closed circuit position to bias said rst and second contact portions into engagement and acting at the same time to bias said switch arm to move it to open circuit position about the other of said pivot axes upon electrically responsive movement of said latch portion.

30. In a circuit interrupter, a relatively ilxed contact, a movable switch member including a movable contact and .a current responsive bimetallic member secured for movement together, two pivot axes about which said switch member is rotatable, manually engageable means operable to cause normal movement of the switch member about one of said pivot axes between open and closed circuit positions, a spring .applying a force to said switch member when in the closed circuit position with the line of action of the force lying between said one pivot axis and said contacts so as to bias said contacts into engagement and also lying on the side of said other pivot axis opposite-the contacts so as to bias said switch member to move with its bimetallic member and contact rotating about said other pivot axis to open circuit position upon deflection of said bimetallic member due to the occurrence of `an abnormal condition in the circuit, and said movement to open circuit position about said other pivot axis taking place irrespective of the position in which said manually engageable means may be held.

31. In a circuit breaker, a movable switch member comprising a contact member and a current carrying bimetal latch secured for movement therewith and electrically connected thereto, .a cooperatinglatch portion normally engaged by said bimetal latch, operating means including a manually engageable portion having means associated therewith providing a pivotal connection to said switch member and operable to cause movement of said switch member about a iixed pivot to open or to closed circuit position as long as said bimetal latch is in latching engagement with said latch portion, and a spring engaging said switch member and operable upon release of said bimetal latch to cause movement of .said switch member about its pivotal connection with said operating means to a tripped open circuit position.

32. A manually and automatically operable circuit breaker comprising a iirst contact, a movable contact cooperating with said rst contact, a current responsive element movable with said movable contact during manual operation of said breaker and having a latch portion controlled thereby,voperating means comprising an operating member manually operable to cause rotation of said movable contact and said current responsive element about a xed pivot into and out of engagement with said rst contact, an actuating spring operable upon movement of said latch portion by the current responsive element to a tripping position to cause rotation of'said movable contact and said current responsive element to a tripped open circuit position about an axis which is movable upon each movement of said manually operable member.

33. In a circuit breaker, a movable switch member comprising a contact and a current responsive bimetal latch secured for movement together, a cooperating latch portion normally engaged by said bimetal latch, operating means including a movable actuating member pivotally engaged with said switch member and operable to cause rotation of said switch member with its contact and bimetal latch moving about a fixed pivot to open or to closed circuit position when said bimetal latch is in latching engagement with said cooperating latch portion, and an actuating spring acting on said switch member and operable upon release oi' said bimetal latch due to a predetermined abnormal condition to cause movement of said switch member with its contact and bimetal latch rotating about its point of pivotal vengagement with said actuating member to a tripped open circuit position.

34. In a circuit breaker, a movable switch member comprising a contact and a current responsive bimetal latch secured for movement together, a cooperating latch portion normally engaged by said bimetal latch, operating means including a movable actuating member pivotally engaged with said switch member and operable to cause rotation of said switch member with its contact and bimetal latch moving about a xed pivot to open or to closed circuit position when said bimetal latch is in latching engagement with said cooperating latch portion, an actuating spring acting on said switch member and operable upon release of said bimetal latch due to a predetermined abnormal condition to cause movement of said switch member with its contact and bimetal latch rotating about its point of pivotal engagement with said actuating member to a tripped open circuit position, and a stop engageable by said switch member vupon movement of said actuating member after said movement of the switch member to tripped open position for causing said movement of the actuating member to return the switch member to a position where its bimetal latch reengages said cooperating latch portion.

35. In .a circuit breaker, a movable switch member including a contact adjacent one end thereof and a current responsive bimetal element secured for movement with said contact and having a latch portion adjacent the other end of the switch member, a cooperating latch element normally engaged by said latch portion on the switch member, operating means comprising a movable actuating member pivotally lengaged with said switch member between the contact end and the latch end thereof, said actuating member being operable to cause movement of said switch member with its contact and bimetal element rotating about a ilxed' pivot to open or to closed circuit position when said latch portion on the switch member is in latching engagement with said latch element, and an actuating spring engaging said switch member between the latch end and the point of pivotal engagement of the actuating member with said switch member, said spring being operable upon release of the latch portion on the switch member from said latch element to cause movement of said switch member with its contact and bimetal element rotating about the point of pivotal engagement of the actuating member and switch member to a tripped open circuit position irrespective of the position in which said actuating member may be held.

36. In a circuit breaker, a movable switch member including a contact adjacent one end thereof and a current responsive bimetal element secured for movement with said contact and having a latch portion adjacent the other end of the switch member, a cooperating latch element normally engaged by said latch portion on the switch member, `operating means com.. prising a movable actuating member pivotally engaged with said switch member between the contact end and the latch end thereof, said actuating member being operable to cause movement of said switch member with its contact and bimetal velement rotating about a fixed pivot to open or to closed circuit position when said latch portion on the switch member is in latching engagement with said latch element, and an actuating spring engaging said switch member between the latch end and the point of pivotal engagement of the actuating member with said switch member, said spring' being operable upon release of the latch portion on the switch member from said latch element to cause movement of said switch member with its contact and bimetal element rotating about the point of pivotal engagement of the actuating member and switch member to a tripped open circuit position irrespective of the position in which said actuating member may be held, and a stop for engaging said switch member adjacent its contact end upon movement of said actuating member when said switch member is in tripped open circuit position and thereby causing movement of said switch member to a position where its latch portion reengages said cooperating latch element.

37. In' a circuit breaker, a pair of spaced terminals, a stationary contact secured to one of said terminals, a movable switch member cornprising a movable contact member and a current responsive bimetal latch secured for movement together and electrically connected to each other, a flexible conductor electrically connecting the latch end of said bimetal latch to the other terminal of said breaker, a latch element normally engaged by said bimetal latch, operating means comprising a movable actuating member above said switch member and having pivotal engagement with said switch member between the contact and the latch end thereof, said actuating member being operable to cause movement of said switch member about a fixed pivot to open or to closed circuit position when said bi- L metal latch is in latching engagement with said latch element, and a spring below said switch member engaging said switch member between the latch end thereof and the point of pivotal engagement of the actuating member with the switch member. said spring being operable upon release of said bimetal latch to cause movement of said switch member about the point of pivotal engagement thereof with said actuating member to a tripped open circuit position.

38. In a circuit breaker, a movable switch member comprising a contact member and a current responsive ybimetal latch, a cooperating latch element normally engaged by said bimetal latch in the latching position thereof, operating means comprising a movable operating handle operable to cause movement of said switch member about one pivot axis to open or to closed circuit position as long as said bimetal latch is in latching engagement with said latch element, and an actuating spring operable upon release of said bimetal latch to cause movement of Said switch member about a different axis to a tripped open positionindependently of the `position of said handle, said bimetal latch being resettable in engagement with said latch element, after cooling, by movement of said operating handle in a switch opening direction.

39. In a circuit interruptor, a base of insulating material, a terminal member having a stationary contact portion thereon mounted on said base, an assembly unit including a movable contact and a current responsive bimetallic member having one end electrically connected to said movable contact and' permanently connected to move with said movable contact, said bimetallic member having a latch portion adjacent the other end thereof, a second terminal member and a flexible conductor electrically connected at one end to said second terminal member and at its other end to said bimetallic member at a point adjacent its latch portion, said assembly unit including the aforesaid parts being positioned on the base with said movable contactl with said stationary contact portion upon current responsive movement of the latch portion of said bimetallic member irrespective of the position in which said operating member may be held.

40. In a circuit interrupter, a base of insulating material, a terminal member having a stationary contact portion thereon mounted on said base, an assembly unit including 'a movable contact and a current responsive bimetallic member having one end electrically connected to said movable contact and permanently connected to move with said movable contact, said bimetallic member having a latch portion adjacent the other end thereof, a second terminal member and a flexible conductor electrically connected at one end to said second terminal member and at its other end to said bimetallic member at a point adjacent its latch portion, said assembly unit including the aforesaid parts being positioned on the base with said movable contact and said bimetallic member free to move together about either of two axes, an operating member movable in opposite directions to cause movement of said movable contact and said bimetallic member together about one of said axes to alternately make and break connection with said stationary contact portion, a spring supported at one end on said base and acting at its other end to bias said movable contact and said bimetallic member to move together about the other of said pivot axes to break connection with said stationary contact portion upon current responsive movement of the latch portion of said bimetallic member irrespective of the position in which said operatingmember may be held, and a stop portion on said base cooperating with said movable contact and said bimetallic member for moving them together upon movement of said operating member in one directiony after said current responsive movement and returning them to a reset position from which they are movable together to make connection with said stationary contact portion upon movement of said operating member in the other direction.

OLIVER S. JENNINGS.

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