Test button assembly for circuit breaker

Information

  • Patent Grant
  • 6710687
  • Patent Number
    6,710,687
  • Date Filed
    Thursday, June 13, 2002
    22 years ago
  • Date Issued
    Tuesday, March 23, 2004
    21 years ago
Abstract
An improved test button assembly for use in a circuit breaker includes a frame and a button member, with the button member being pivotably mounted on the frame. A pair of microswitches are mounted on a printed circuit board that is disposed on the frame. The button member is alternately engageable with the two microswitches, with one of the microswitches being connectable with a ground fault protection circuit, and the other microswitch being connectable with an arc fault protection circuit. In an alternate embodiment, a common electrical contact is mounted on the button member, and a pair of contacts are mounted on the frame, with the common contact being alternately engageable with each of the contacts mounted on the frame. The contacts mounted on the frame are connected with the ground fault and arc fault protection circuits.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates generally to power distribution equipment and, more particularly, to a test button assembly for a circuit breaker.




2. Description of the Related Art




Circuit breakers and other power distribution equipment are well known in the relevant art. Circuit breakers are typically configured to interrupt current upon the occurrence of one or more predetermined conditions. For instance, circuit breakers may trip in the event of an overcurrent condition or an under-voltage condition, and they additionally trip in the event of a ground fault or an arc-fault condition if configured to do so. Protection from ground faults and arc faults typically is provided by circuitry within the circuit breaker that is operatively connected with a trip unit of the circuit breaker.




In order to ensure the continued proper and safe operation of such circuit breakers, the ground fault and arc fault detection circuitry is desirably tested on occasion. The testing of such ground fault and arc fault circuitry typically involves the closing of a pair of contacts within a testing circuit that simulates the fault condition. Upon closing of the contacts and simulation of the fault condition, a successful test of the fault detection circuitry will result in the trip unit of the circuit breaker performing a trip operation. The circuit breaker can then be reset. While such testing circuitry has been generally effective for its intended purpose, such testing circuitry has not, however, been without limitation.




Circuit breakers generally are designed in such a fashion to minimize the space occupied thereby. As such, the contacts that are closed in order to test ground fault and arc fault circuitry typically have been mounted directly onto a main printed circuit board of the circuit breaker. In some instances the contacts have been configured as leaf springs that protrude from the main printed circuit board and are deflected into contact with one another in order to close the ground fault or arc fault protection circuit.




The deflection of such leaf spring contacts undesirably results in forces and torques being applied to the main printed circuit board. Since numerous other circuitry components of the circuit breaker are mounted on the main printed circuit board, such forces and torques can result in breakage or other failure of the main printed circuit board and thus the circuit breaker.




Additionally, since such contacts are disposed internally within the circuit breaker, some type of linkage or other motion transfer mechanism must be provided which operatively extends between the contacts and the exterior of the circuit breaker to permit the contacts to be closed from the exterior of the circuit breaker. Such linkages and the like occupy additional space within the circuit breaker and are often less than fully reliable in closing the contacts of the protection circuitry. Such contacts and linkages additionally have been relatively expensive to incorporate into a circuit breaker.




It is thus desired to provide an improved test button assembly for a circuit breaker that overcomes these and other shortcomings of previously known test button designs.




SUMMARY OF THE INVENTION




Accordingly, an improved test button assembly for use in a circuit breaker includes a frame and a button member, with the button member being pivotably mounted on the frame. A pair of microswitches are mounted on a printed circuit board that is disposed on the frame. The button member is alternately engageable with the two microswitches, with one of the microswitches being connectable with a ground fault protection circuit, and the other microswitch being connectable with an arc fault protection circuit. In an alternate embodiment, a common electrical contact is mounted on the button member, and a pair of contacts are mounted on the frame, with the common contact being alternately engageable with each of the contacts mounted on the frame. The contacts mounted on the frame are connected with the ground fault and arc fault protection circuits.




Accordingly, an aspect of the present invention is to provide an improved test button assembly that is relatively less expensive to manufacture and incorporate into a circuit breaker than previously known test button systems.




Another aspect of the present invention is to provide an improved test button assembly that is relatively more reliable in function than previously known test button systems.




Another aspect of the present invention is to provide an improved test button assembly that is modular in nature.




Another aspect of the present invention is to provide an improved test button assembly that is configured such that the operation thereof imparts generally no forces or torques to a main circuit board of the circuit breaker.




Another aspect of the present invention is to provide an improved test button assembly for a circuit breaker that occupies minimal space within the circuit breaker.




Another aspect of the present invention is to provide an improved circuit breaker that employs an improved test button assembly.




Accordingly, an aspect of the present invention is to provide a test button assembly for a circuit breaker, the circuit breaker including a first protection system and a second protection system, the circuit breaker including a case formed with a receptacle, in which the general nature of the test button assembly can be stated as including a frame, a button member, the button member being mounted on the frame, the button member being movable with respect to the frame, a first contact, the first contact being disposed on the frame, the first contact being structured to be electrically conductively connected with the first protection system, a second contact, the second contact being disposed on the frame, the second contact being structured to be electrically conductively connected with the second protection system, a common contact, the common contact being operatively connected with the button member, the common contact being movable by the button member to be electrically conductively connectable with the first contact, the common contact being movable by the button member to be electrically conductively connectable with the second contact, and the test button assembly being a discrete unit that is structured to be received in the receptacle and mounted to the case of the circuit breaker as a single assembly.




Another aspect of the present invention is to provide a test button assembly for a circuit breaker, the circuit breaker including a first protection system and a second protection system, the circuit breaker including a case formed with a receptacle, in which the general nature of the test button assembly can be stated as including a frame, a first microswitch, the first microswitch being disposed on the frame, the first microswitch being structured to be electrically conductively connected with the first protection system, a second microswitch, the second microswitch being disposed on the frame, the second microswitch being structured to be electrically conductively connected with the second protection system, a button member, the button member being mounted on the frame, the button member being movable with respect to the frame, the button member being operatively engageable with the first microswitch, the button member being operatively engageable with the second microswitch, and the test button assembly being a discrete unit that is structured to be received in the receptacle and mounted to the case of the circuit breaker as a single assembly.




Another aspect of the present invention is to provide a circuit breaker the general nature of which can be stated as including a case, a trip unit, the trip unit being disposed within the case, a line conductor, a load conductor, the line and load conductors being electrically conductively connectable with one another, the trip unit being operative to electrically conductively connect and disconnect the line and load conductors, a first protection system, the first protection system being operatively connected with the trip unit, a second protection system, the second protection system being operatively connected with the trip unit, a test button assembly, the test button assembly including a first microswitch, the test button assembly including a second microswitch, the test button assembly including a support, the first microswitch being mounted on the support, the second microswitch being mounted on the support, the support being disposed on the case, the first microswitch being operatively connected with the first protection system, and the second microswitch being operatively connected with the second protection system.











BRIEF DESCRIPTION OF THE DRAWINGS




A further 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 a schematic cut-away view of an improved circuit breaker in accordance with the present invention that incorporates an improved test button assembly in accordance with a first embodiment of the present invention;





FIG. 2

is a sectional view as taken along line


2





2


of

FIG. 1

;





FIG. 3

is a sectional view as taken along line


3





3


of

FIG. 2

;





FIG. 4

is a top plan view of a switch assembly of the first embodiment;





FIG. 5

is a view similar to

FIG. 3

, except depicting a button member of the first embodiment operatively engaged with a first microswitch of the first embodiment;





FIG. 6

is view similar to

FIG. 5

, except depicting the button member operatively engaged with a second microswitch of the first embodiment;





FIG. 7

is a sectional end view of an improved test button assembly in accordance with a second embodiment of the present invention;





FIG. 8

is a sectional view as taken along line


8





8


of

FIG. 7

;





FIG. 9

is a view similar to

FIG. 8

, except depicting a common contact of the second embodiment electrically conductively engaged with a first contact of the second embodiment;





FIG. 10

is view similar to

FIG. 9

, except depicting the common contact electrically conductively connected with a second contact of the second embodiment.











Similar numerals refer to similar parts throughout the specification.




DESCRIPTION OF THE PREFERRED EMBODIMENTS




A circuit breaker


4


in accordance with the present invention is illustrated schematically in FIG.


1


. The circuit breaker


4


is advantageously configured to include a test button assembly


8


in accordance with a first embodiment of the present invention. The test button assembly


8


is employed for the testing of protection circuitry of the circuit breaker


4


. The test button assembly


8


is advantageously of a modular configuration, as will be set forth more fully below.




The circuit breaker


4


includes a case


12


, a trip unit


16


, a first protection system


20


, a second protection system


24


, a first conductor


28


, and a second conductor


32


. The trip unit


16


, the first protection system


20


, and the second protection system


24


are disposed within the case


12


. The first conductor


28


and the second conductor


32


each extend between the interior of the case


12


and the exterior thereof. As is well known in the relevant art, the first and second conductors


28


and


32


may be line and load conductors, respectively, and include contacts


30


and


34


, respectively. The contacts


30


and


34


are engaged with one another (not shown in

FIG. 1

) such that the first and second conductors


28


and


32


are electrically conductively connected with one another during normal operation of the circuit breaker


4


. The contacts


30


and


34


are disengaged from one another by the trip unit


16


upon the occurrence of one or more specified conditions to disconnect the first and second conductors


28


and


32


from one another, all in a known fashion. The first and second conductors


28


and


32


are intended to be connected with a line and a load, as is well understood in the relevant art.




The trip unit


16


can include one or more of any of a wide variety of trip systems such as thermal trip systems, magnetic armature trip systems, under-voltage trip systems, and the like in a well understood fashion. The first and second protection system


20


and


24


can likewise each be any of a variety of protection systems such as ground fault protection systems and arc fault protection systems. As can be understood from

FIG. 1

, the first and second protection systems


20


and


24


are each operatively connected with the trip unit such that upon the occurrence of a specified condition, either or both of the first and second protection systems


20


and


24


will trigger the trip unit


16


to disconnect the first and second conductors


28


and


32


in order to interrupt the current through the circuit breaker


4


in a well understood fashion.




As can further be understood from

FIG. 1

, the case


12


is formed to include a receptacle


36


. The test button


8


is advantageously received in the receptacle


36


and is thereby disposed on the case


12


. As such, the test button assembly


8


advantageously is not mounted on either of the first and second protection systems


20


and


24


or on a main printed circuit board (not explicitly depicted in

FIG. 1

) upon which the first and second protection systems


20


and


24


may be mounted.




As can be understood from

FIGS. 2 and 3

, the test button assembly


8


includes a frame


40


, a button member


44


, and a switch assembly


48


. The button member


44


and the switch assembly


48


are both mounted on the frame


40


, whereby the test button assembly


8


is modular in nature and can be readily mounted onto the case


12


of the circuit breaker


4


. As used herein, the term “modular” and variations thereof refers to a condition in which multiple components or parts are connected with one another in such a fashion that the components or parts together form a discrete unit or module that can be handled and employed as a single assembly. In the context of the test button assembly


8


, the test button assembly


8


is a discrete unit or module that can be mounted as a single assembly on the circuit breaker


4


by slidingly receiving the test button assembly


8


in the receptacle


36


of the case


12


, as will be set forth more fully below.




The frame


40


includes a base


52


, a pair of parallel and spaced apart walls


56


extending from the base


52


, and a pair of legs


60


that each include a locking tab


64


and that extend away from the base


52


. The base


52


and the walls


56


together are generally U-shaped. The legs


60


extend away from the base


52


in a direction opposite the walls


56


.




The button member


44


includes a pair of axially aligned pins


68


that are pivotably mounted in correspondingly sized and positioned holes (not shown) formed in the walls


56


. In the embodiment of the test button assembly


8


depicted in the accompanying figures, the button member


44


does not itself include a spring or other structure to bias the button member


44


to a particular position, and rather is free to pivotably float. It is understood, however, that such a spring or other biasing structure could be added to the test button assembly


8


without departing from the concept of the present invention.




During mounting of the test button assembly


8


to the case


12


, the test button assembly


8


is translated toward the case


8


to receive the legs


60


in the receptacle


36


. The engagement of the locking tabs


64


with the walls of the receptacle causes the legs


60


to deflect generally toward one another. The receptacle


36


terminates at a pair of opposed ledges


72


. As the test button assembly


8


further slidingly received in the receptacle


36


, the locking tabs


64


ultimately move past the ledges


72


, and the legs


60


spring back into the position depicted in

FIG. 3

so that the test button assembly


8


snaps into place.




As can be understood from

FIG. 2

, the case


12


also includes a pair of stops


76


formed on the interior of the receptacle


36


for engagement with the base


52


. It thus can be seen that the locking tabs


64


function as mounting structures that permit the test button assembly


8


to be lockably engaged with the case


12


. Moreover, the test button assembly


8


, being of a modular configuration, is received in the receptacle


36


and is thus mounted on the case


12


as a discrete unit. While the ledges


72


and the stops


76


together fixedly retain the test button assembly


8


within the receptacle


36


, it is understood that other structures and assembly methodologies may be employed to retain the test button assembly


8


in the receptacle


36


.




As can be understood from

FIGS. 2 and 3

, the switch assembly


48


includes a generally planar support


80


, a first microswitch


84


, and a second microswitch


88


. The switch assembly


48


further includes a first wire


112


, a second wire


116


, and a common wire


120


that extend from the support


80


. The support


80


may be any of a wide variety of structural support members and may be a small printed circuit board. It can be seen that the support


80


is received in a pair of confronting notches


92


(

FIG. 2

) formed in the walls


56


.




The first and second microswitches


84


and


88


are substantially identical to one another, although such identity is not essential to the operation of the test button assembly


8


. The first microswitch


84


includes a first plunger


94


, a first terminal


96


, and a second terminal


100


. Similarly, the second microswitch


88


includes a second plunger


102


, a first terminal


104


, and a second terminal


108


. As is understood in the relevant art, the first plunger


94


is movable and is operable to change the first microswitch


84


between an open condition in which the first and second terminals


96


and


100


are electrically conductively disconnected from one another and a closed condition in which the first and second terminals


96


and


100


are electrically conductively connected together. The first plunger


94


is spring biased to the open condition. The second plunger


102


is similarly movable and operable to change the second microswitch


88


between open and closed positions in which the first and second terminals


104


and


108


are disconnected and connected together, respectively. The second plunger


102


is spring biased to the open condition. The first and second microswitches


84


and


88


may, for instance, each be a Mechanical Keyswitch B3F-1000 sold by Omron Electronics, Inc., of Schaumburg, Ill., USA, although other switches from other manufacturers may be employed without departing from the concept of the present invention.




As can be understood from

FIG. 4

, the first terminal


96


of the first microswitch


84


is electrically conductively connected with the first wire


112


. The first wire


112


is electrically conductively connected with the first protection system


20


. Similarly, the first terminal


104


of the second microswitch


88


is electrically conductively connected with the second wire


116


. The second wire


116


is electrically conductively connected with the second protection system


24


. It can further be seen that the second terminals


100


and


108


are electrically conductively connected with one another and with the common wire


120


.




It thus can be understood that when the button member


44


is moved into operative engagement with the first microswitch


84


, as is depicted generally in

FIG. 5

, the first plunger


94


is depressed by the button member


44


which places the first microswitch


84


in the closed condition in which the first and second terminals


96


and


100


are connected with one another. Such a circumstance closes the circuit of the first protection system


20


which, if in proper operating condition, triggers the trip unit


16


to separate the first and second conductors


28


and


32


. Similarly, when the button member


44


is in operative engagement with the second microswitch


88


, as is generally depicted in

FIG. 6

, the second plunger


102


is depressed by the button member


44


which electrically conductively connects the first and second terminals


104


and


108


which closes the circuit of the second protection system


24


. If the second protection system


24


is in proper operating condition it triggers the trip unit


16


to separate the first and second conductors


28


and


32


. In such fashion, the first and second protection systems


20


and


24


can be tested.




It can be seen from

FIG. 3

that the first, second, and common wires


112


,


116


, and


120


extend from the support


80


through a hole


124


formed in the base


52


for connection with the appropriate components of the circuit breaker


4


. It is understood, however, that in other embodiments of the test button assembly


8


, the first, second, and common wires


112


,


116


, and


120


may be routed in a different fashion and thus may not extend through any such hole


124


.




It thus can be seen that the test button assembly


8


is of a modular configuration and can be received in the receptacle


36


and secured therein by the engagement of the locking tabs


64


with the ledges


72


and the engagement of the base


52


with the stops


76


. With the test button assembly


8


installed as such, the first, second, and common wires


112


,


116


, and


120


can be electrically conductively connected with appropriate components within the circuit breaker


4


such that the first microswitch


84


is operatively connected with the first protection system


20


and the second microswitch


88


is operatively connected with the second protection system


24


. The test button assembly


8


is relatively small in physical size, with the size thereof being generally dictated by and limited by the size of the first and second microswitches


84


and


88


. Depending upon the availability of other microswitches, the test button assembly


8


can be configured to be even more compact than that explicitly depicted herein.




Since the first and second microswitches


84


and


88


include first and second plungers


94


and


102


that are biased to the open condition, the button member


44


need not be separately biased to a neutral position but rather may be permitted to pivotably float while being retained between the walls


56


. Furthermore, the test button assembly


8


is operated without applying any forces or torques to any components of the circuit breaker


4


other than the case


12


. As such, the potential for breakage or other failure of a main printed circuit board or other components of the circuit breaker


4


due to the application of forces or torques thereto is substantially alleviated.




It is understood that the test button assembly


8


depicted in the accompanying figures is merely exemplary in nature and can be configured in numerous different fashions without departing from the concept of the present invention. For instance, the notches


92


could be formed in the case


12


, with the support


80


being received in such notches. In such fashion, the frame


40


could be eliminated from the test button assembly


8


. Moreover, the switch assembly


48


could be additionally or alternatively disposed such that the first and second plungers


94


and


102


protrude slightly through correspondingly sized and positioned holes formed in a cover extending over the receptacle


36


such that the first and second plungers


94


and


102


could be manually engaged. Such a configuration would additionally eliminate the need for a button member


44


. Such alternate configurations of the test button assembly


8


could be incorporated into the circuit breaker


4


depicted generally in

FIG. 1

without the departing from the concept of the present invention.




It is noted, however, that the button member


44


of the present invention is configured to function as a rocker to alternately test the first and second protection systems


20


and


24


. As such, a user can advantageously determine which of the first and second protection systems


20


and


24


, if either, is functioning improperly. If the first and second protection systems


20


and


24


were tested simultaneously, one could not determine whether or not one of the first and second protection systems


20


and


24


was malfunctioning unless both were malfunctioning.




A second embodiment of a test button assembly


208


is indicated generally in

FIGS. 7-10

. The test button assembly


208


includes a frame


240


and a button member


244


that are substantially similar to those of the test button assembly


8


. The test button assembly


208


includes a switch assembly


248


, however, that includes a first bar


282


, a second bar


286


, and a common bar


290


. The first and second bars


282


and


286


are mounted on the frame


240


and are retained in position by a pair of first protrusions


328


and a pair of second protrusions


332


, respectively, formed on the frame


240


.




The common bar


290


is a reentrantly formed generally T-shaped member that is made from a single bar of spring wire that is bent to such shape. The common bar


290


is engaged with the button member


244


and biases the button member


244


to a neutral position that is depicted generally in FIG.


8


.




It can further be seen that the first bar


282


extends through a first hole


336


and is connected with a first wire


312


. The second bar


286


extends through a second hole


340


and is connected with a second wire


316


. The common bar


290


extends through a third hole


344


and is connected with a common wire


320


. It is understood, of course, that the first, second, and common wires


312


,


316


, and


320


could be routed in different fashions. The first, second, and common wires


312


,


316


, and


320


are connectable in a fashion similar to the first, second, and common wires


112


,


116


, and


120


of the test button assembly


8


.




It can be seen from

FIG. 9

that the button member


244


is pivotable to a first position in which the common bar


290


is electrically conductively connected with the first bar


282


which completes a first circuit. Similarly, the button member


244


can be pivoted to a second position (

FIG. 10

) in which the common bar


290


is electrically conductively connected with the second bar


286


, which completes a second circuit. The common bar


290


is alternately electrically conductively connectable with the first and second bars


282


and


286


.




It thus can be seen that the test button assembly


208


could be substituted for and have a similar operation to that of the test button assembly


8


. In such fashion, the first wire


312


could be electrically conductively connected with the first protection system


20


, and the second wire


316


could be electrically conductively connected with the second protection system


24


. Moreover, the test button assembly


208


could be incorporated into the circuit breaker


4


depicted generally in FIG.


1


.




The test button assemblies


8


and


208


thus are modular in configuration, and the operation thereof generally applies no forces to any components of the circuit breaker


4


other than to the case


12


. The test button assemblies


8


and


208


are relatively inexpensive to manufacture and are reliable in their operation and advantageously do not increase the potential for breakage or other failure of the main circuit board or other components of the circuit breaker


4


.




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 the 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 case; a trip unit; the trip unit being disposed within the case; a line conductor; a load conductor; the line and load conductors being electrically conductively connectable with one another; the trip unit being operative to electrically conductively connect and disconnect the line and load conductors; a first protection system; the first protection system being operatively connected with the trip unit; a second protection system; the second protection system being operatively connected with the trip unit; a test button assembly; the test button assembly including a first microswitch; the test button assembly including a second microswitch; the test button assembly including a support; the first microswitch being mounted on the support; the second microswitch being mounted on the support; the support being disposed on the case; the first microswitch being operatively connected with the first protection system; and the second microswitch being operatively connected with the second protection system.
  • 2. The circuit breaker as set forth in claim 1,in which the first microswitch includes a first terminal; the first terminal of the first microswitch being electrically conductively connected with the first protection system; the first microswitch including a second terminal; the second microswitch including a first terminal; the first terminal of the second microswitch being electrically conductivity connected with the second protection system; the second microswitch including a second terminal; the second terminals of the first and second microswitches being electrically conductively connected together.
  • 3. The circuit breaker as set forth in claim 2,in which the first and second microswitches each include a plunger; each plunger being operable to change the respective microswitch between an open condition in which the first and second terminals at the respective microswitch are electrically conductively disconnected from one another and a closed condition in which the first and second terminals of the respective microswitch are electrically conductively connected together.
  • 4. The circuit breaker as set forth in claim 1,in which the test button assembly includes a frame; the support being disposed on the frame; the frame being disposed on the case.
  • 5. The circuit breaker as set forth in claim 4,in which the test button assembly includes a button member; the button member being mounted on the frame; the button member being movable with respect to the frame; the button member being operatively engageable with the first microswitch; the button member being operatively engageable with the second microswitch.
  • 6. The circuit breaker as set forth in claim 5, in which the button member is pivotable with respect to the frame.
  • 7. The circuit breaker as set forth in claim 5,in which the test button assembly is a discrete unit that is received in the receptacle and mounted to the case of the circuit breaker as a single assembly.
US Referenced Citations (2)
Number Name Date Kind
6259340 Fuhr et al. Jul 2001 B1
6392513 Whipple et al. May 2002 B1