Circuit breaker

Abstract
A circuit breaker includes a housing; separable contacts mounted in the housing; and an operating mechanism for opening and closing the separable contacts. An overcurrent assembly is responsive to selected conditions of current flowing through the separable contacts and actuates the operating mechanism to trip open the separable contacts. A bonnet forms a U-shape which surrounds the separable contacts and which cools and splits an arc when the operating mechanism trips open the separable contacts. A first bonnet piece forms a first leg of the bonnet, and a second bonnet piece forms a second leg and a base of the bonnet.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to electrical switching apparatus and, more particularly, to circuit breakers, such as, for example, aircraft circuit breakers.




2. Background Information




Circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. In small circuit breakers, commonly referred to as miniature circuit breakers, used for residential and light commercial applications, such protection is typically provided by a thermal-magnetic trip device. This trip device includes a bimetal, which heats and bends in response to a persistent overcurrent condition. The bimetal, in turn, unlatches a spring powered operating mechanism, which opens the separable contacts of the circuit breaker to interrupt current flow in the protected power system.




Subminiature circuit breakers are used, for example, in aircraft electrical systems where they not only provide overcurrent protection but also serve as switches for turning equipment on and off. As such, they are subjected to heavy use and, therefore, must be capable of performing reliably over many operating cycles. They also must be small to accommodate the high-density layout of circuit breaker panels, which make circuit breakers for numerous circuits accessible to a user. Aircraft electrical systems usually consist of hundreds of circuit breakers, each of which is used for a circuit protection function as well as a circuit disconnection function through a push-pull handle.




The circuit breaker push-pull handle is moved from in-to-out in order to open the load circuit. This action may be either manual or, else, automatic in the event of an overload or fault condition. If the push-pull handle is moved from out-to-in, then the load circuit is re-energized. If the load circuit had been automatically de-energized, then the out-to-in operation of the push-pull handle corresponds to a circuit breaker reset action.




Typically, subminiature circuit breakers have only provided protection against persistent overcurrents implemented by a latch triggered by a bimetal responsive to I


2


R heating resulting from the overcurrent. There is a growing interest in providing additional protection, and most importantly arc fault protection. Arc faults are typically high impedance faults and can be intermittent. Nevertheless, such arc faults can result in a fire.




Although many circuit breakers also employ ground fault protection, in aircraft applications, the aircraft frame is ground, and there is no neutral conductor. Some aircraft systems have also provided ground fault protection, but through the use of additional devices, namely current transformers which in some cases are remotely located from the protective relay.




During sporadic arcing fault conditions, the overload capability of the circuit breaker will not function since the root-mean-squared (RMS) value of the fault current is too small to activate the automatic trip circuit. The addition of electronic arc fault sensing to a circuit breaker can add one of the elements required for sputtering arc fault protection—ideally, the output of an electronic arc fault sensing circuit directly trips and, thus, opens the circuit breaker. It is still desirable, however, to provide separate indications in order to distinguish an arc fault trip from an overcurrent-induced trip.




Finally, there is an interest in providing an instantaneous trip in response to very high overcurrents such as would be drawn by a short circuit.




The challenge is to provide alternative protection and separate indications in a very small package, which will operate reliably with heavy use over a prolonged period. A device which meets all the above criteria and can be automatically assembled is desirable.




In aircraft applications, two practical considerations make automatic operation difficult to achieve and, possibly, undesirable. First, the design of a conventional aircraft circuit breaker makes it difficult to add an externally initiated tripping circuit thereto. Second, certain circuits on an aircraft are so critical that manual intervention by a crewmember may be desirable before a circuit is de-energized.




It is known to employ a conventional U-shaped bonnet around an arc chamber of a circuit breaker.




There is room for improvement in circuit breakers.




SUMMARY OF THE INVENTION




According to one aspect of the invention, a circuit breaker comprises: a housing; separable contacts mounted in the housing; an operating mechanism for opening and closing the separable contacts; an overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for actuating the operating mechanism to trip open the separable contacts; and a bonnet having first and second pieces, the first piece forming a first leg of the bonnet, the second piece forming a second leg and a base of the bonnet, in order to form a U-shape which surrounds the separable contacts and which cools and splits an arc when the operating mechanism trips open the separable contacts.




As another aspect of the invention, a circuit breaker comprises: a housing; a pair of separable contacts mounted in the housing; an operating mechanism for opening and closing the separable contacts; a first terminal electrically interconnected with a first one of the separable contacts; a second terminal electrically connected to a second one of the separable contacts; an electrically conductive support mechanism mounted in the housing; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for actuating the operating mechanism to trip open the separable contacts, the bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to the selected conditions of current to actuate the operating mechanism, with the first leg engaging and being electrically connected to the support mechanism, with the second leg electrically connected to the first terminal, and with the support mechanism electrically interconnected with the first one of the separable contacts.




As a further aspect of the invention, a circuit breaker comprises: a housing having an opening therein; separable contacts mounted in the housing; a latchable operating mechanism comprising: a toggle mechanism having first and second pivotally connected toggle links coupled to the separable contacts for opening and closing the separable contacts, an operating handle assembly coupled to the toggle mechanism, the handle assembly including first and second pieces, with the first piece secured to the second piece, the first piece providing a first visual impression and the second piece providing a different second visual impression, and a latch assembly latching the toggle mechanism in a latched condition in which the toggle mechanism is manually operable by the handle assembly between a toggle open position and a toggle closed position to open and close the separable contacts, the latch assembly including a latch member which when released unlatches the toggle mechanism to open the separable contacts; and an overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for releasing the latch member to trip the separable contacts open, wherein the first piece of the handle assembly is internal to the housing when the separable contacts are closed, wherein the second piece of the handle assembly is external to the housing, and wherein a portion of the first piece of the handle assembly is external to the housing when the separable contacts are open.




As another aspect of the invention, a circuit breaker comprises: a housing including a molded case, a molded cover and an external clip plate securing the molded cover to the molded case; separable contacts mounted in the housing; an operating mechanism for opening and closing the separable contacts; and an overcurrent assembly responsive to selected conditions of current flowing through the separable contacts for actuating the operating mechanism to trip open the separable contacts.




Preferably, the clip plate includes a top and two sides disposed therefrom, with one of the sides capturing the molded case and the other of the sides capturing the molded cover.











BRIEF DESCRIPTION OF THE DRAWINGS




A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:





FIG. 1

is an exploded isometric view of a circuit breaker in accordance with the present invention.





FIG. 2

is another exploded isometric view from the opposite end of FIG.


1


.





FIG. 3

is a front elevation view of the circuit breaker of

FIG. 1

, with one-half of the cover and two top plates removed, showing the circuit breaker in the off condition.





FIG. 4

is a view similar to

FIG. 3

but showing the circuit breaker in the on condition.





FIG. 5

is a view similar to

FIG. 3

but showing the circuit breaker in the tripped condition.





FIG. 6

is an exploded isometric view of the operating mechanism and two top plates of the circuit breaker of FIG.


1


.





FIG. 7

is an isometric view of the load terminal, bimetal, mechanism plate, movable contact arm and line terminal of the circuit breaker of FIG.


1


.





FIG. 8

is an isometric view of the operating mechanism and bonnet of the circuit breaker of FIG.


1


.





FIG. 9

is a partially exploded isometric view of the molded case and bonnet of the circuit breaker of

FIG. 1

showing z-axis assembly of the bonnet.





FIG. 10

is an exploded isometric view of two parts of the handle assembly of the circuit breaker of FIG.


1


.





FIG. 11

is an isometric view of the assembled handle assembly of FIG.


10


.





FIG. 12

is an isometric view of the trip motor, dual latch trip actuator and bimetal of the circuit breaker of FIG.


1


.





FIG. 13

is an exploded isometric view of the trip motor of FIG.


12


.





FIG. 14

an isometric view of the dual trip, dual latch trip actuator of the circuit breaker of

FIG. 1

in the latched position.





FIG. 15

is a view similar to

FIG. 14

but showing the dual trip, dual latch trip actuator in the unlatched position.





FIG. 16

is an isometric view of the operating handle assembly, the trip actuator and the arc fault indicator assembly of the circuit breaker of

FIG. 1

, with the cover and some internal portions thereof not shown for clarity.





FIG. 17

is an isometric view of the arc fault indicator of FIG.


16


.





FIG. 18

is an isometric view of the circuit breaker of

FIG. 1

with the handle in the trip position and the arc fault indicator assembly in the arc fault trip position.





FIG. 19

is a view similar to

FIG. 18

but showing the handle and the arc fault indicator assembly in the normal positions.





FIG. 20

is a front elevation view of the combined light pipe trip indicator ring and trip actuator of the circuit breaker of

FIG. 1

in the latched position.





FIG. 21

an isometric view of the indicator ring and trip actuator of FIG.


20


.





FIG. 22

is a view similar to

FIG. 21

but showing the indicator ring and the trip actuator in the unlatched position.





FIGS. 23 and 24

show other circuit breakers including housings in accordance with alternative embodiments of the invention.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




The invention will be described as applied to a subminiature circuit breaker for use in aircraft alternating current (AC) systems, which are typically 400 Hz, but can also be used in direct current (DC) systems. It will also become evident that the invention is applicable to other types of circuit breakers including those used in AC systems operating at other frequencies; to larger circuit breakers, such as miniature residential or commercial circuit breakers; and to a wide range of circuit breaker applications, such as, for example, residential, commercial, industrial, aerospace, and automotive. As further non-limiting examples, both AC (e.g., 120, 220, 480-600 VAC) operation at a wide range of frequencies (e.g., 50, 60, 120, 400 Hz) and DC operation (e.g., 42 VDC) are possible.




Referring to

FIGS. 1 and 2

, an exemplary circuit breaker


1


has a housing


3


formed by first and second sections


3




a


and


3




b


molded of an insulative resin which sections are joined along a mating plane to form an enclosure from confronting cavities


5




a


and


5




b


, respectively. The circuit breaker


1


also includes an external clip plate


7


having a top


9


and two sides


11


,


13


disposed therefrom. The clip plate side


11


captures the section or molded case


3




a


and the other clip plate side


13


captures the other section or molded cover


3




b


. Each of the sides


11


,


13


includes an opening


15


,


17


, respectively, proximate the bottom of the corresponding side. The molded case


3




a


and the molded cover


3




b


each have a respective opening


19


(shown in

FIG. 2

) and


20


therethrough. A fastener


21


, such as a rivet, is disposed through the opening


15


of the side


11


, through the openings


19


,


20


of the molded case


3




a


and the molded cover


3




b


, and through the opening


17


of the side


13


, in order to draw the one side


11


toward the other side


13


and, thereby, secure the molded case


3




a


to the molded cover


3




b


(as best shown in FIG.


19


).




The circuit breaker


1


further includes an operating mechanism


22


mounted on a support mechanism such as the exemplary mechanism jig plate


23


(as best shown in FIGS.


4


and


7


), a first mechanism top plate


24


, a second mechanism top plate


25


(the top plates


24


,


25


are best shown in FIG.


6


), and a bezel


29


mounted in an opening


30


of the housing


3


. The bezel


29


is held in place by the external clip plate


7


and housing


3


. In turn, a suitable fastener, such as the exemplary nut


31


and washer


31


a mount the circuit breaker


1


to a mounting panel (not shown). The circuit breaker


1


also includes a line terminal


32


, a load terminal


33


, and an operating handle assembly


35


, which protrudes through the opening


30


and the bezel


29


. The operating handle assembly


35


is suitably biased away from the opening


30


by a spring


36


. For ON/OFF operation, the handle assembly


35


is driven up by springs


63


and


36


. Spring


36


is employed on trip operations to reset the handle assembly


35


to the OFF position.




The circuit breaker


1


further includes a movable and illuminable arc fault indicator


37


, an arc fault detector


39


including exemplary printed circuit boards (PCBs)


41


,


43


, and an insulator


45


. Suitable arc fault detectors are disclosed, for instance, in U.S. Pat. No. 5,224,006, with a preferred type described in U.S. Pat. No. 5,691,869, which are hereby incorporated by reference. In the exemplary embodiment, the mechanism plate


23


is electrically conductive and is preferably made of stainless steel or brass. The operating mechanism


22


is assembled to and supported by the mechanism plate


23


, which is mounted in the cavity


5




a


of the molded section


3




a


, and the PCBs


41


,


43


are mounted in the cavity


5




b


of the molded section


3




b.






Referring to

FIGS. 3-5

, the functional components of the circuit breaker


1


include a separable contact assembly


47


(as best shown in FIGS.


4


and


5


), a toggle mechanism


49


, the handle assembly


35


, a latch member assembly


51


, and an overcurrent assembly


53


. The toggle mechanism


49


, handle assembly


35


, and latch assembly


51


form the latchable operating mechanism


22


. The circuit breaker


1


also includes the line terminal


32


and the load terminal


33


supported in the bottom of the molded case


3




a


and having cantilevered sections extending outside of the case


3


for connection to respective line and load conductors (not shown).




As discussed below in connection with

FIG. 12

, the overcurrent assembly


53


includes a trip motor


119


(for arc fault conditions), and a bimetal


129


(for persistent overcurrent conditions). The overcurrent assembly


53


also includes an instantaneous trip function, which like the trip motor


119


and bimetal


129


, actuate the latch assembly


51


to trip open the separable contact assembly


47


.




The separable contact assembly


47


includes a fixed contact


55


fixed to the line terminal


32


and a moveable contact


57


carried by and electrically connected to a movable contact arm


58


within the housing


3


. The fixed contact


55


and moveable contact


57


together form a set of separable contacts


59


. The contact arm


58


is pivotally mounted on a metal pin


61


, which is part of mechanism plate


23


. The plates


24


,


25


(

FIG. 6

) retain the contact arm


58


on the pin


61


. A cantilever leaf spring


63


forms a main spring, which biases the contact arm


58


counter-clockwise (with respect to

FIGS. 3-5

) to open the separable contacts


59


(as shown in FIG.


5


). As discussed below in connection with

FIG. 7

, the load terminal


33


is electrically interconnected with the contact arm


58


and the moveable contact


57


, and the line terminal


32


is electrically connected to the fixed contact


55


. The latchable operating mechanism


22


functions to open (

FIGS. 3 and 5

) and close (

FIG. 4

) the separable contacts


59


.




The contact arm


58


is pivoted between open (

FIG. 3

) and closed (

FIG. 4

) positions of the separable contacts


59


by the toggle mechanism


49


. This toggle mechanism


49


includes a lower toggle link


65


pivotally connected by a pin


66


(shown in hidden line drawing in

FIG. 3

) at a first or lower end


67


to the contact arm


58


at a pivot point


69


. In this manner, the toggle mechanism


49


is mechanically coupled to the separable contacts


59


for opening and closing such separable contacts.




A second toggle link


71


is pivotally connected at a first or upper end


73


by a pin


75


to a latch lever


77


, which in turn is pivotally mounted by a metal pin


79


that is part of mechanism plate


23


. The second ends of the first toggle link


65


and the second toggle link


71


are pivotally connected by a knee pin


81


. The toggle mechanism


49


further includes a drive link


83


, which mechanically couples the toggle mechanism


49


to the handle assembly


35


.




Whenever the latch assembly


51


is actuated, the latch lever


77


is unlatched and the main spring


63


drives the movable contact arm


58


upward in order to open the separable contacts


59


. Also, through movement of the links


65


,


71


, the latch lever


77


is rotated clockwise (with respect to FIG.


5


). From this tripped position, the spring


36


(

FIGS. 1 and 2

) returns the handle assembly


35


to the OFF position, and the latch lever return spring


85


returns the latch lever


77


, in order that it can be engaged by the latch member assembly


51


. Otherwise, the latch assembly


51


latches the latch lever


77


and the toggle mechanism


49


in a latched condition (

FIGS. 3 and 4

) in which the toggle mechanism


49


is manually operable by the handle assembly


35


between a toggle open position (

FIG. 3

) and a toggle closed position (

FIG. 4

) to open and close the separable contacts


59


.




As can be seen from

FIG. 5

, the handle assembly


35


includes a handle member


87


having a stem


89


. The drive link


83


of the toggle mechanism


49


is pivotally connected to the stem


89


by a pin


91


. The handle member


87


is supported for reciprocal linear movement by the bezel


29


. The latch lever


77


has a finger


93


terminating in a hook


95


(as best shown in FIGS.


14


and


15


), which engages (

FIGS. 3 and 4

) an opening


97


in the latch assembly


51


.




The exemplary circuit breaker


1


operates in the following manner. In the OFF position (FIG.


3


), which is the toggle open position of the toggle mechanism


49


, the handle member


87


is up with an indicator portion


99


of the stem


89


visible to indicate the OFF condition. The latch lever


77


is latched by engagement of its hook


95


by the opening


97


in the latch assembly


51


. The main spring


63


has rotated the movable contact arm


58


counter-clockwise (with respect to

FIG. 3

) against a stop portion


101


of the mechanism plate


23


so that the separable contacts


59


are open.




Depressing the handle member


87


, which moves linearly downward to the position shown in

FIG. 4

, turns ON the circuit breaker


1


. The drive link


83


pushes the knee pin


81


downward and to the right, and the first toggle link


65


downward, which results in clockwise rotation (with respect to

FIGS. 3 and 4

) of the movable contact arm


58


against the main spring


63


. As the upper end of the second (upper) toggle link


71


is held stationary by the latch lever


77


, the toggle mechanism


49


in general, and the first (lower) link


65


in particular, seats against a stop portion


103


of the mechanism plate


23


in the toggle closed position shown in FIG.


4


. This latter motion occurs through clockwise rotation (with respect to

FIG. 4

) of the contact arm


58


, which is pivotally mounted on the pin


61


at the slotted aperture


105


thereof. With the separable contacts


59


closed in this manner, the main spring


63


provides contact pressure on the separable contacts


59


and accommodates for wear.




The circuit breaker


1


may be manually opened from the ON position (

FIG. 4

) to the OFF position (

FIG. 3

) by raising the handle member


87


. Initially, a downward force is applied to the contact arm


58


through the first toggle link


65


. However, when the knee pin


81


passes through the center line between the pins


91


and


75


, the toggle mechanism


49


breaks and the main spring


63


rotates the movable contact arm


58


counter-clockwise (with respect to

FIGS. 3 and 4

) until it seats against the stop


101


with the separable contacts


59


open. In turn, the handle


87


rises to the OFF position (FIG.


3


).




As discussed below in connection with

FIGS. 7 and 12

(persistent overcurrent conditions),

FIGS. 13-15

(arc fault conditions), and

FIGS. 3-6

(instantaneous trip conditions), the circuit breaker


1


can be tripped (

FIG. 5

) to the open condition under various conditions. Regardless of such conditions, the latch assembly


51


releases the latch lever


77


, which is driven clockwise (with respect to

FIGS. 4 and 5

) about the pin


79


. Also, the movable contact arm


58


is driven counter-clockwise (with respect to

FIGS. 4 and 5

) through the main spring


63


to open the separable contacts


59


.




In this transitory trip position, the handle member


87


is down, the latch lever


77


is rotated clockwise, and the movable contact arm


58


is in the open position. From this position, the handle spring


36


returns the handle member


87


to the OFF position and the latch lever spring


85


rotates the latch lever


77


counter-clockwise to a position where it can be engaged by the latch assembly


51


. This is the OFF position.




The lower end of the handle spring


36


engages an inside surface (not shown) of the bezel


29


. The inside of the bezel


29


forms a cup (not shown), with a relatively small hole (not shown) in the center thereof. That hole is of sufficient size, in order to permit the relatively small end


199


of the handle


35


to pass therethrough. The handle spring


36


biases the handle


35


in the direction away from the bezel


29


, in order to drive the handle to the OFF position. In the ON position (FIG.


4


), links


65


,


71


have passed straight alignment (and, thus, have passed the toggle position), and the main spring


63


prevents the handle


35


from opening. The forces of the main spring


63


and the handle spring


36


are predetermined in order that the main spring


63


prevents the handle spring


36


from opening the circuit breaker


1


. If the circuit breaker


1


is tripped (FIG.


5


), then the main spring


63


drives the movable contact arm


58


to the stop


101


, and the force of the main spring is no longer involved in the force balance. Hence, the handle spring


36


can then move the handle


35


to the OFF position. Otherwise, when the circuit breaker


1


is ON and a user pulls on the handle


35


, that force is added to the handle spring force until there is sufficient force to overcome the main spring force and open the circuit breaker.




Referring to

FIGS. 1 and 6

, there are five exemplary electrical connections to the PCB


41


. Additional pins (not shown) electrically interconnect the PCBs


41


,


43


. Two terminals


109


,


111


pass through openings


112


,


114


of the insulator


45


and electrically connect mating terminals


113


,


115


, respectively, of the PCB


41


to a coil assembly


117


of a trip motor or electromagnet assembly


119


(e.g., a solenoid of

FIGS. 12 and 13

. Another two terminals


121


,


123


pass through openings


124


,


126


of the insulator


45


and electrically connect mating terminals


125


,


127


, respectively, of the PCB


41


across the series combination of a bimetal


129


and the mechanism plate


23


, in order to sense current flowing to the load terminal


33


. The terminal


121


is electrically connected to the load terminal


33


and to one end (


164


as best shown in

FIG. 7

) of the bimetal


129


. The other terminal


123


is electrically connected to the mechanism plate


23


, which is electrically connected to the other end (


165


as best shown in

FIG. 7

) of the bimetal


129


.




The electronic circuit (not shown) of the PCBs


41


,


43


measures the voltage between the terminals


125


,


127


and calculates the circuit breaker load current from the known resistance (e.g., about 5 to 100 milliohms depending on rated current) of the series combination of the bimetal


129


and mechanism plate


23


(i.e., I=V/R). In turn, the electronic circuit determines if an arc fault condition is present and, if so, energizes the terminals


113


,


115


, in order to energize the coil assembly


117


and effect an arc fault trip (as discussed below in connection with FIGS.


13


-


15


). A fifth terminal


131


(FIGS.


1


-


5


), which is electrically connected to the bezel


29


, passes through opening


132


of the insulator


45


and is electrically connected to mating terminal


133


of the PCB


41


, in order to provide a suitable external ground reference thereto. The PCBs


41


,


43


derive power from voltage between the terminals


123


,


131


. Whenever a suitable voltage is present, the PCBs


41


,


43


illuminate a light emitting diode (LED)


135


(FIG.


1


), which is employed in connection with the arc fault indicator


37


, as shown near the bottom of the bezel


29


of FIG.


3


.




As shown in

FIGS. 1 and 6

, the terminals


109


and


111


pass through corresponding openings


137


and


139


, respectively, of mechanism top plates


24


,


25


, without electrically contacting those plates. The mechanism top plates


24


,


25


are held in place by three rivet pins


141


,


143


and


145


formed on the metal pin


79


, the metal pin


61


, and a metal pin


147


(as best shown in FIG.


3


), which holds the bottom end of the spring


85


, respectively. In turn, the rivet pins


141


,


143


,


145


engage the mechanism top plates


24


,


25


at corresponding openings


149


,


151


,


153


, respectively, thereof. The pin


123


, which is electrically connected to the mechanism plate


23


, electrically engages the top plates


24


,


25


at the opening


155


. Another opening


157


of the top plates


24


,


25


pivotally supports a pivot point


159


of the latch assembly


51


.




The exemplary top plates


24


,


25


have a similar, but non-identical shape, with the first top plate


24


being cut away in some areas in order to maintain clearance for certain moving parts of the operating mechanism


22


, and the second top plate


25


adding thickness to the first top plate


24


and providing an L-shaped portion


160


for the instantaneous (magnetic) trip function as discussed below in connection with

FIGS. 3-6

. Preferably, the plates


24


,


25


are initially formed from the same die.





FIG. 7

shows the load terminal


33


, an overcurrent assembly


161


which includes the bimetal


129


, the mechanism plate


23


, the movable contact arm


58


, the separable contacts


59


and the line terminal


32


of the circuit breaker


1


of FIG.


1


. The bimetal


129


has two leg portions


162


,


163


and is fixed and electrically connected at one end or a first foot


164


to the load terminal


33


. The other bimetal end or a second foot


165


engages and is electrically connected to the mechanism plate


23


, which, in turn, is electrically connected to the movable contact arm


58


by a pigtail, such as flexible braided conductor


167


, which is suitably electrically attached (e.g., by welding) at each end. In this manner, the load current flows from the line terminal


32


to the fixed contact


55


, to the movable contact


57


, to the movable contact arm


58


, to the braided conductor


167


, and to the mechanism plate


23


, before passing through the bimetal


129


and to the load terminal


33


. In the exemplary embodiment, the bimetal


129


is designed for 2.5 A rated load current, although the invention is applicable to a wide range of rated currents (e.g. 15 A or greater). The load current causes I


2


R heating of the bimetal


129


resulting in movement of its upper portion (with respect to

FIG. 7

) to the right side of

FIG. 7

, with all of the exemplary load current flowing through the bimetal


129


. A 15 A bimetal, for example, is U-shaped, and has almost three times the cross section of the exemplary bimetal


129


, and can carry more current without fusing.




The exemplary bimetal


129


includes an intermediate U-shaped section


169


, which is electrically connected in series between the first leg


162


and the first foot


164


and the second leg


163


and the second foot


165


. As discussed below in connection with

FIG. 12

, the bimetal


129


deflects in response to selected conditions of load current flowing through the separable contacts


59


to actuate the latch assembly


51


. Hence, the bimetal


129


is responsive to selected conditions (e.g., overload, fault current conditions) of such load current and actuates the operating mechanism


22


through the trip latch


229


(

FIG. 12

) in order to trip open the separable contacts


59


.




The exemplary mechanism plate


23


provides improved support for the bimetal


129


since the second foot


165


of the bimetal


129


is attached to the plate


23


. This provides improved routing of current through the bimetal


129


from the separable contacts


59


, to the movable contact arm


58


, to the conductor


167


, to the plate


23


, and to the bimetal foot


165


, which is attached to the plate


23


. Furthermore, this provides a simpler routing of the conductor


167


(i.e., from the plate


23


to the movable contact arm


58


), rather than from the bimetal foot


165


or leg


163


to the movable contact arm


58


).




Referring to

FIGS. 8 and 9

, a bonnet assembly


171


for the separable contacts


59


of

FIG. 4

is shown. The bonnet assembly


171


includes two metal (e.g. made of steel) pieces


173


,


175


, each having an L-shape, of which the first piece


173


forms a first leg


177


of the assembly


171


, and the second piece


175


forms a second leg


179


and a base


181


of the assembly


171


, in order to form a U-shape, which surrounds the separable contacts


59


and which cools and splits an arc when the operating mechanism


22


trips open the separable contacts


59


. The molded case


3




a


(

FIG. 9

) includes two slots


183


,


185


therein. The exemplary first piece


173


has a tab


189


, which engages the slot


183


. The exemplary second piece


175


has two exemplary tabs


191


,


193


, which engage the slot


185


of the molded case


3




a


. Although the exemplary bonnet assembly


171


has a generally rectangular U-shape, the invention is applicable to bonnet assemblies having a rectangular or a rounded U-shape.




The exemplary U-shape (as best shown in FIG.


8


), as formed by the bonnet assembly


171


, has the first leg


177


formed by the first L-shaped piece


173


, the base


181


formed by the second L-shaped piece


175


, and the second leg


179


formed by the second L-shaped piece


175


. The second L-shaped piece


175


has a notch


195


between the two tabs


191


,


193


thereof. The first L-shaped piece


173


has an end


197


, which rests in the notch


195


between the tabs


191


,


193


of the second L-shaped piece


175


. The other end of the first L-shaped piece


173


has the tab


189


, which engages the slot


183


. The tabs


189


and


191


,


193


of the respective first and second L-shaped pieces


173


and


175


mount the bonnet assembly


171


to the molded case


3




a


and, thus, advantageously permit z-axis assembly of that assembly


171


, with the initial insertion of the first L-shaped piece


173


being followed by subsequent insertion of the second L-shaped piece


175


.





FIGS. 10 and 11

show the handle assembly


35


of the circuit breaker


1


of FIG.


1


. The handle assembly


35


includes a first piece or stem portion


199


, and a second piece or cap portion


201


. In the exemplary embodiment, the stem portion


199


is made of molded plastic having a light (e.g., white) color, and the cap portion


201


is made of molded plastic having a dark (e.g., black) color. As shown in

FIG. 11

, the stem portion


199


is secured to the cap portion


201


, with the stem portion


199


providing a first visual impression and the cap portion


201


providing a different second visual impression.




As shown in

FIG. 4

, the stem portion


199


is internal to the cavity


3




a


of the housing


3


(

FIG. 1

) when the separable contacts


59


are closed, and the cap portion


201


is external to the housing


3


, thereby providing a first visual impression (e.g., the dark color of the cap portion


201


) in the handle ON position. Otherwise, as shown in

FIGS. 3 and 5

, the indicator portion


99


of the stem portion


199


of the handle assembly


35


is external to the housing


3


when the separable contacts


59


are open (i.e., OFF, tripped open). As shown in

FIG. 10

, the stem portion


199


has a stem


203


with two ears or protrusions


205


,


207


at each side of the upper (with respect to

FIG. 10

) end thereof. The cap portion


201


has an open end


209


and an annular wall


211


with two openings


213


,


215


therein. The annular wall


211


also has two channels


217


,


219


therein, which channels are offset from the two openings


213


,


215


, respectively. When the handle assembly


35


is assembled, the stem


203


of the stem portion


199


is inserted into the open end


209


of the cap portion


201


, with the ears


205


,


207


being in the channels


217


,


219


of the annular wall


211


. Then, the cap portion


201


is rotated clockwise (with respect to

FIG. 10

) by an exemplary one-quarter turn, in order to engage the ears


205


,


207


in the openings


213


,


215


, respectively, thereby locking the two portions


199


,


201


together as shown in FIG.


11


. In this manner, the handle assembly


35


provides two-piece snap together construction and does not rotate apart. Hence, this provides an operating handle or button with sufficient strength and, also, provides a clear indication through the distinctly different visual impressions of the two molded portions


199


,


201


, in order to show breaker status (i.e., OFF/tripped versus ON).




Although the exemplary embodiment employs different colors in order to provide distinct different visual impressions of the two portions


199


,


201


, the invention is applicable to a wide range of such portions that provide distinctly different visual impressions by, for example, distinct textures (e.g., smooth vs. rough), distinct patterns (e.g., a lined vs. a checked pattern, striped vs. solid), and/or distinct combinations thereof (e.g., a solid blue color vs. a striped pattern). Although a two-piece handle assembly


35


is shown, the invention is applicable to single- and plural-piece operating handles which preferably include distinct visual impressions in order to show breaker status.




The stem portion


199


is preferably molded to include a metal (e.g. made of stainless steel) insert


221


having an opening


223


to receive the pin


91


of FIG.


4


.





FIG. 12

shows the overcurrent assembly


53


including the trip motor or electromagnet assembly


119


and the bimetal


129


. A cantilevered ambient compensation bimetal


225


is operatively associated with the bimetal


129


. One end


227


of this ambient compensation bimetal


225


is suitably fixed to a trip latch member


229


of the latch assembly


51


, such as by spot welding. The cantilevered ambient compensation bimetal


225


extends upward (with respect to

FIG. 12

) to terminate in a free end


231


, which is adjacent to a free end


233


of the bimetal


129


. Under normal operating conditions, there is a gap between the free end


233


of the bimetal


129


and the free end


231


of the ambient compensation bimetal


225


. When the bimetal


129


is heated, it moves to the right (with respect to

FIG. 12

) as shown by line


235


. An exemplary shuttle


237


made of plastic or some other suitable insulating material has notches


238


and


239


, which engage the free ends


233


and


231


of the bimetal


129


and the ambient compensation bimetal


225


, respectively. The bimetal


129


, when heated, moves the shuttle


237


, thus, pulling on the ambient compensation bimetal


225


, which, in turn, is attached to the trip latch


229


. An increase or decrease in ambient temperature conditions cause the free end


233


of the bimetal


129


and the free end


231


of the ambient compensation bimetal


225


to move in the same direction and, thereby, maintain the appropriate gap between the two bimetal free ends


231


,


233


, in order to eliminate the effects of changes in ambient temperature. Hence, the bimetal


129


and the cantilevered ambient compensation bimetal


225


are coupled in series to the trip latch


229


to move the same in response to a persistent overcurrent condition as compensated for ambient conditions. Under overcurrent conditions, the bimetal


129


, therefore, pulls on the ambient bimetal


225


, which rotates the trip latch


229


of the latch assembly


51


clockwise (with respect to

FIG. 12

, or counter-clockwise with respect to

FIG. 6

) around the pivot point


159


(

FIG. 6

) and releases the latch lever


77


to trip the operating mechanism


22


.




The thermal trip can be calibrated by a calibration screw


240


, which engages the molded case


3




a


of FIG.


2


and which is threaded into a nut


241


disposed between a lower surface


243


of the bimetal


129


and the fixed end


227


of the ambient compensation bimetal


225


. By further threading and tightening the screw


240


into the nut


241


, the nut


241


engages the lower bimetal surface


243


and drives the bimetal free end


233


to the right (with respect to

FIG. 12

) as shown by line


235


. Alternatively, reversing the screw


240


out of the nut


241


, allows the bimetal free end


233


to return to the left (with respect to FIG.


12


).




As shown in

FIG. 13

, the trip motor assembly


119


includes a motor base


245


made of magnetic steel, the coil assembly


117


, and the terminals


109


,


111


. The base


245


includes an opening


247


, which fixedly engages one end of the spring


63


of

FIG. 3

, and also includes an exemplary oval hole


249


therein, which hole mates with a corresponding oval protrusion feature


251


in the mechanism plate


23


of

FIG. 7

for location of the motor assembly


119


. In turn, the motor assembly


119


is secured between the back wall


253


of the molded case


3




a


of FIG.


9


and the mechanism plate


23


.




The exemplary motor coil assembly


117


has a magnetically permeable motor core


254


which fits inside a coil sleeve (not shown) within an electrical coil


256


. The motor core


254


is connected at one end


255


to the base


245


. The coil assembly


117


is housed in a magnetically permeable motor cup


260


, which together with the magnetically permeable core


254


, form a magnetic circuit. The motor core


254


holds the coil


256


within an opening


257


thereof. A pin or terminal holder


258


projects laterally outward through a slot (not shown) in the motor cup


260


and supports the terminals


109


,


111


. The trip motor coil assembly


117


is energized through the terminals


109


,


111


by an electronic trip circuit (e.g., arc fault, ground fault) provided on the PCBs


41


,


43


of FIG.


1


. In the exemplary embodiment, only an arc fault trip circuit is provided.




The exemplary circuit breaker


1


includes three different trip modes, all of which employ the trip latch


229


of

FIG. 4

to actuate the operating mechanism


22


and trip open the separable contacts


59


: (1) overcurrent conditions (i.e., thermal trip) detected by the bimetal


129


(FIGS.


7


and


12


), which actuates the trip latch


229


through the shuttle


237


and ambient compensation bimetal


225


; (2) arc fault (and/or ground fault) conditions detected by the PCBs


41


,


43


, which energize the trip motor


119


to actuate the trip latch


229


(FIGS.


14


and


15


); and (3) relatively high current conditions (i.e., instantaneous trip), which also attract the trip latch


229


(FIGS.


3


-


6


).




As shown in

FIG. 12

, the mechanism plate


23


has two posts


259


,


261


, which engage corresponding holes


263


,


265


, respectively, within the cavity


5




a


of the molded case


3




a


(FIG.


9


). Preferably, the posts


259


,


261


and holes


263


,


265


provide an alignment function, with the insulator


45


, PCBs


41


,


43


and molded cover


3




b


, as secured by the clip plate


7


, holding the operating mechanism


22


, mechanism plate


23


and trip motor


119


within the housing


3


of FIG.


1


.




Referring to

FIGS. 14 and 15

, the motor coil


256


is fixedly held by the motor core


254


of

FIG. 13

, with one end of the coil


256


(and, thus, one end of the motor core


254


) facing an armature section


267


of the trip latch


229


. When the coil assembly


117


is energized, the trip latch armature section


267


is attracted toward the motor core, thereby rotating the upper portion


269


right (with respect to

FIG. 14

) to an unlatched position. As discussed above in connection with

FIG. 5

, actuation of the trip latch


229


trips open the separable contacts


59


. Hence, for protection against arc faults, the electronic trip circuit of the PCBs


41


,


43


, which is responsive to selected arc fault conditions of current flowing through the separable contacts


59


, monitors the load current (i.e., through terminals


121


,


123


of

FIG. 6

) for characteristics of such faults, and energizes (i.e., through the terminals


109


,


111


of

FIG. 6

) the trip motor coil assembly


117


. In turn, the magnetic flux generated by the energization of the coil assembly


117


attracts the trip latch armature section


267


toward the motor core (as shown in FIG.


15


), in order to slide the hook


95


out of the trip latch opening


97


, thereby tripping the circuit breaker


1


open in the manner discussed above for a thermal trip.





FIG. 16

shows the operating handle assembly


35


in the raised OFF position (of FIG.


3


), and the movable and illuminable arc fault indicator


37


in a raised tripped position. The indicator


37


(as best shown in

FIG. 17

) includes a first leg or movable member


271


having a notch


272


near the lower end thereof. The notch


272


is engaged by a first arm


273


of a spring


275


. The spring


275


has a central portion


277


, which is held by a pin


279


on the mechanism plate


23


, and a second arm


281


, which is held between side-by-side pins


283


,


285


on the plate


23


. The indicator


37


of

FIG. 17

also includes a second leg or light pipe member


273


and an illuminable ring portion


274


, which is connected to the legs


271


,


273


. The illuminable ring portion


274


is a first portion of the movable and illuminable arc fault indicator


37


, and the legs


271


and


273


are a second portion of the indicator


37


, which is normally recessed within the bezel


29


of the housing


3


(FIGS.


3


-


5


). Under normal operating conditions, the PCB


41


energizes the LED


135


(

FIG. 1

) from an internal voltage, which is derived from the normal line-ground voltage between the terminals


123


,


131


(FIGS.


1


and


6


). The free end of the light pipe


273


is normally proximate the LED


135


(

FIG. 3

) and normally receives light therefrom when the arc fault PCBs


41


,


43


are properly energized. Hence, the LED


135


normally illuminates the light pipe


273


and, thus, the illuminable ring portion


274


. The illuminable ring portion


274


is visible in

FIGS. 3-5

, in order to indicate, when lit, proper energization of the arc fault PCBs


41


,


43


.




Referring to

FIGS. 14 and 15

, the trip motor


119


also includes an indicator latch


287


, which is pivotally mounted on a pin


289


disposed on the mechanism plate


23


of FIG.


16


. The indicator latch


287


includes an upper latch portion


291


having an opening


293


therein, and a lower armature portion


295


. The indicator latch


287


is disposed at one end of the trip motor


119


and the trip latch


229


is disposed at the opposite end thereof. As shown in

FIG. 14

, there is a first gap


297


between the right (with respect to

FIG. 14

) end of the trip motor cup


260


and the trip latch armature


267


, and there is a second gap


299


between the left (with respect to

FIG. 14

) end of the cup


260


and the indicator latch armature


295


. In response to current applied to the coil assembly


117


, the trip motor


119


creates flux and attracts one of the latches


229


,


287


thereto, which closes a corresponding one of the gaps


297


,


299


, thereby lowering the reluctance of the coil assembly


117


, increasing the trip motor flux, and attracting the other one of the latches


229


,


287


, in order to close the other corresponding one of the gaps


297


,


299


, as shown in FIG.


15


. For example, it is believed that the trip motor


119


first attracts the indicator latch


287


, which requires less actuation force than that required by the trip latch


229


, although the invention is applicable to trip motors which first attract a trip latch, or which simultaneously attract indicator and trip latches.




With the indicator latch


287


in the position of

FIG. 15

, the end


301


of the spring leg


273


disengages from the indicator latch opening


293


, and the spring leg


273


drives the movable member


271


upward with respect to

FIG. 16

, thereby driving the indicator ring


274


upward to the arc fault trip position of

FIGS. 16 and 18

. In that position, the light pipe


273


(

FIG. 17

) is separated from the LED


135


(FIG.


1


). Also, power is removed to the PCBs


41


,


43


. Hence, the illuminable ring portion


274


is no longer lit.





FIG. 18

shows the circuit breaker


1


with the operating handle assembly


35


in the handle trip position following an arc fault (and/or thermal and/or instantaneous) trip condition, and the indicator ring


274


disposed away from the housing


3


in the arc fault trip position following an arc fault trip condition. Normally, these positions result from an arc fault trip, although, as discussed below, may, alternatively, result from a previous arc fault trip, after which the operating handle assembly


35


, but not the illuminable ring portion


274


, was reset, followed by a thermal and/or instantaneous trip. The illuminable ring portion


274


protrudes through the opening


30


of the housing


3


of FIG.


1


and through an opening


302


of the bezel


29


. The ring portion


274


surrounds an upper stem portion


303


of the operating handle assembly


35


.




An important aspect of the present invention is the capability of the exemplary operating handle assembly


35


to operate independently from the arc fault indicator


37


. In this manner, following any trip, the operating handle assembly


35


may be reset to the ON position of

FIG. 4

, without moving the arc fault indicator


37


from the arc fault trip indicating position of FIG.


18


. For example, during aircraft operation, it may be highly advantageous during operation of a critical or important power system to re-energize such system through the operating handle assembly


35


, while leaving the arc fault indicator


37


in its arc fault trip indicating position. In this manner, the aircraft may be safely operated (e.g., the risk of not energizing that power system outweighs the risk of an arc fault), while leaving the arc fault indicator


37


deployed for the subsequent attention by maintenance personnel only after the aircraft has safely landed. Similarly, the arc fault indicator


37


may be reset from the arc fault trip indicating position of

FIG. 18

by pressing downwardly on the illuminable ring portion


274


, in order to reengage the spring leg end


301


with the indicator latch opening


293


(FIG.


21


), without moving the operating handle assembly


35


between the OFF and ON positions thereof.





FIG. 19

shows the normal operating condition of the circuit breaker


1


in which both the operating handle assembly


35


and the indicator ring


274


are in the normal positions. Also, as long as power is suitably applied to the circuit breaker


1


, the illuminable ring portion


274


is normally lit by light from the LED


135


(

FIG. 1

) as energized by line-ground voltage between the terminal


123


(FIG.


6


), which has the line voltage from the line terminal


32


, and the terminal


131


(FIG.


4


), which has the ground potential from the bezel


29


and/or a mounting panel (not shown)). Thus, the LED


135


is normally lit in the event that the arc fault PCBs


41


,


43


(

FIG. 1

) are energized and is, otherwise, not lit (e.g., power is not present; the bezel


29


is improperly grounded).




Referring to

FIGS. 20-22

, the indicator leg


271


is engaged by the spring


275


and is mechanically held down by the indicator latch


287


(FIGS.


20


and


21


). When an arc fault trip condition occurs, the indicator latch


287


is actuated to the position shown in FIG.


22


. When the indicator latch


287


is so moved, the spring


275


is released from the indicator latch opening


293


, which allows the spring


275


to push up the indicator leg


271


internal to the housing


3


of

FIG. 1

, thereby moving the indicator ring


274


away from and external to the housing


3


as shown in

FIG. 18

, in order to indicate an arc fault trip condition.




As shown in

FIG. 20

, the latch return spring


107


extends through an opening


305


of the motor base


245


(as best shown in FIG.


13


). The spring


107


drives the indicator latch


287


clockwise and drives the trip latch


229


counter-clockwise (with respect to

FIG. 20

) and, thus, drives both of the dual latches


229


,


287


.




Although the invention has been described in terms of a dual trip/indicator latch formed by the exemplary trip motor


119


, the trip latch


229


, and the indicator latch


287


, the invention is applicable to single and dual latch functions which actuate an indicator latch, in order to indicate an arc fault or ground fault condition, and/or which actuate a trip latch, in order to trip open separable contacts. The invention is further applicable to an indicator latch, which normally engages a movable member of an indicator, and which releases such member for movement by a spring.




In order to provide an instantaneous trip, the overcurrent assembly


53


of

FIGS. 3-5

includes an arrangement for routing a current path of a main conductor, as formed by the bimetal


129


, the mechanism plate


23


, the flexible braid


167


and the movable contact arm


58


of

FIG. 7

, through a magnetic circuit, as formed by the motor frame


245


of FIG.


12


and the two steel mechanism top plates


24


,


25


of FIG.


6


. The motor frame


245


and plates


24


,


25


form a steel shape around this current path. The discontinuous electrical conduction paths of the exemplary magnetic circuit direct the magnetic flux to flow once through the general path of the steel shape, thereby forming a one-turn electromagnet. Whenever load current flows in the circuit breaker


1


, the steel shape magnetically attracts the steel trip latch


229


. The magnetic coupling is such that suitably high load currents of at least a predetermined magnitude (e.g., without limitation, about 300 A for a 2.5 A rated load), such as those associated with short circuits, are sufficient to actuate the trip latch


229


, without energizing the trip motor coil assembly


117


. If the load current is of sufficient magnitude, then the trip latch


229


is rotated in the counter-clockwise direction (with respect to FIG.


5


), thereby tripping the circuit breaker


1


.




For example, magnetic flux flows around any current carrying conductor and, preferably, flows in steel. Hence, the exemplary steel shape around the exemplary load current path concentrates and channels the magnetic flux to flow through the exemplary steel path. Although the magnetic flux preferably flows in the steel, it also crosses any gaps in such steel. Therefore, the top plates


24


,


25


are preferably close to the motor frame


245


, although physical connection is not required. When the magnetic flux crosses a gap in its path around the discontinuous electrical conduction paths, a force is generated toward closing that gap. Hence, since the steel path encompassing those conduction paths includes gaps between the motor frame


245


and the trip latch


229


, and between the L-shaped portion


160


of the top plate


25


and the trip latch


229


, forces are generated toward closing those gaps and, thus, actuating the trip latch


229


.




As shown in

FIG. 23

, a circuit breaker


306


is similar to the circuit breaker


1


of

FIG. 1

, except that a fastener


307


is disposed through the openings


17


and


15


(shown in

FIG. 1

) of the clip plate


7


, and beneath the molded case


309




a


and the molded cover


309




b


, in order to draw the one side


11


toward the other side


13


and to secure the molded case


309




a


to the molded cover


309




b.






As shown in

FIG. 24

, a circuit breaker


311


is similar to the circuit breaker


1


of

FIG. 1

, except that the molded case


313




a


and the molded cover


313




b


each have channels


315




a


,


315




b


, respectively. A fastener


317


is disposed through the openings


15


,


17


of the clip plate sides


11


,


13


and within the channels


315




a


,


315




b


, in order to draw the one side


11


toward the other side


13


, thereby, securing the molded case


313




a


to the molded cover


313




b.






The exemplary circuit breaker


1


is a simple and reliable mechanism, which selectively provides multiple protection functions as well as serving as an off/on switch. This arrangement also lends itself to automated assembly. The molded section


3




a


of the housing


3


is placed on a flat surface and the parts are all inserted from above. The mechanism plate


23


, the operating mechanism


22


, the handle assembly


35


, the latch assembly


51


, the bimetals


129


,


225


, and the bonnet assembly


171


, all fit into the cavity


5




a


in this housing section


3




a


. The trip motor


119


is seated behind the mechanism plate


23


, and the PCBs


41


,


43


are connected by electrical pins


109


,


111


,


121


,


123


,


131


. The PCBs


41


,


43


extend into the cavity


5




b


of the housing section


3




b


. The sections


3




a


,


3




b


, in turn, are secured together by the clip plate


7


and fastener


21


. In one embodiment, the exemplary circuit breaker


1


is about 1 to 1.2 in. tall, about 1 in. wide, and about 0.8 in. thick.




While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.



Claims
  • 1. A circuit breaker comprising:a housing; a pair of separable contacts mounted in said housing; an operating mechanism for opening and closing said separable contacts; a first terminal electrically interconnected with a first one of said separable contacts; a second terminal electrically connected to a second one of said separable contacts; an electrically conductive support mechanism mounted in said housing; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through said separable contacts for actuating said operating mechanism to trip open said separable contacts, said bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to said selected conditions of current to actuate said operating mechanism, with the first leg engaging and being electrically connected to said support mechanism, with the second leg electrically connected to said first terminal, with said operating mechanism carrying and being electrically connected to said first one of said separable contacts, and with said support mechanism supporting and being electrically connected to said operating mechanism.
  • 2. A circuit breaker comprising:a housing; a pair of separable contacts mounted in said housing; an operating mechanism for opening and closing said separable contacts; a first terminal electrically interconnected with a first one of said separable contacts; a second terminal electrically connected to a second one of said separable contacts; an electrically conductive support mechanism mounted in said housing; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through said separable contacts for actuating said operating mechanism to trip open said separable contacts, said bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to said selected conditions of current to actuate said operating mechanism, with the first leg engaging and being electrically connected to said support mechanism, with the second leg electrically connected to said first terminal, and with said support mechanism electrically interconnected with said first one of said separable contacts, said free intermediate section is a U-shaped section electrically connected in series between said first leg and said second leg.
  • 3. A circuit breaker comprising:a housing; a pair of separable contacts mounted in said housing; an operating mechanism for opening and closing said separable contacts, said operating mechanism includes a movable contact arm carrying and electrically connected to a first one of said separable contacts; a first terminal electrically interconnected with the first one of said separable contacts; a second terminal electrically connected to a second one of said separable contacts; an electrically conductive support mechanism mounted in said housing, said support mechanism includes a flexible conductor having two ends, with the first end of said flexible conductor electrically connected to said support mechanism, and with the second end of said flexible conductor electrically connected to the movable contact arm; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through said separable contacts for actuating said operating mechanism to trip open said separable contacts, said bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to said selected conditions of current to actuate said operating mechanism, with the first leg engaging and being electrically connected to said support mechanism, with the second leg electrically connected to said first terminal, and with said support mechanism electrically interconnected with said first one of said separable contacts.
  • 4. A circuit breaker comprising:a housing; a pair of separable contacts mounted in said housing; an operating mechanism for opening and closing said separable contacts; a first terminal electrically interconnected with a first one of said separable contacts; a second terminal electrically connected to a second one of said separable contacts; an electrically conductive support mechanism plate mounted in said housing, said operating mechanism is assembled to and supported by said support mechanism plate; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through said separable contacts for actuating said operating mechanism to trip open said separable contacts, said bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to said selected conditions of current to actuate said operating mechanism, with the first leg engaging and being electrically connected to said support mechanism plate, with the second leg electrically connected to said first terminal, and with said support mechanism plate electrically interconnected with said first one of said separable contacts.
  • 5. A circuit breaker comprising:a housing; a pair of separable contacts mounted in said housing; an operating mechanism for opening and closing said separable contacts; a first terminal electrically interconnected with a movable one of said separable contacts; a second terminal electrically connected to a fixed one of said separable contacts; an electrically conductive support mechanism mounted in said housing and supporting said operating mechanism; and a bimetal overcurrent assembly responsive to selected conditions of current flowing through said separable contacts for actuating said operating mechanism to trip open said separable contacts, said bimetal overcurrent assembly having first and second legs and a free intermediate section which deflects in response to said selected conditions of current to actuate said operating mechanism, with the first leg engaging and being electrically connected to said support mechanism, with the second leg electrically connected to said first terminal, with said operating mechanism carrying and being electrically connected to said movable one of said separable contacts, and with said support mechanism being electrically connected to said operating mechanism.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to commonly assigned, concurrently filed U.S. patent application Ser. No. 09/845,943, filed Apr. 30, 2001, entitled “Circuit Breaker Having A Movable And Illuminable Arc Fault Indicator”; and U.S. patent application Ser. No. 09/845,517, filed Apr. 30, 2001, entitled “Circuit Breaker Including An Arc Fault Trip Actuator Having An Indicator Latch And A Trip Latch”. This application is also related to commonly assigned, co-pending U.S. patent application Ser. No. 09/506,871, filed Feb. 15, 2000, entitled “Circuit Breaker With Instantaneous Trip Provided By Main Conductor Routed Through Magnetic Circuit Of Electronic Trip Motor”.

US Referenced Citations (7)
Number Name Date Kind
3456225 Ellenberger Jul 1969 A
4990882 Peter Feb 1991 A
5224006 MacKenzie et al. Jun 1993 A
5459446 Vidal et al. Oct 1995 A
5691869 Engel et al. Nov 1997 A
6040747 Krasser et al. Mar 2000 A
6307460 Yu Oct 2001 B1
Foreign Referenced Citations (1)
Number Date Country
2036436 Jun 1980 GB