SLIM CIRCUIT BREAKER

Abstract

A circuit breaker design allows for the circuit breaker to have an overall height (i.e., measured vertically along the circuit breaker's exposed outwardly-facing surface in the typical orientation of circuit breaker panels) that is slimmer than achievable with known typical configurations, while at the same time still providing robust power (e.g., voltage) handling and arc interruption capabilities. This is achieved, for example, by providing various components formed from polymer materials (which are generally less conductive of heat than metals), reinforced by metal members in certain areas, if needed, as well as a very particular configuration of a permanent magnet that is employed for enhanced arc quenching.

Claims

1. A circuit breaker comprising: a housing within which components of the circuit breaker are disposed; a line terminal adapted to be electrically connected to a source of electrical power; a load terminal adapted to be electrically connected to at least one load; a stationary contact positioned within the housing; a moveable contact arm assembly having a generally longitudinal axis and a moveable contact positioned thereon at a first end, the moveable contact arm assembly being pivotably mounted within said housing at a second end and being pivotable about the second end between a closed position in which the moveable contact and the stationary contact are in physical contact and the line terminal and the load terminal are in electrical communication, and an open position in which the moveable contact and the stationary contact are out of physical contact and the line terminal and the load terminal are out of electrical communication; an overcurrent tripping device operably coupled to the moveable contact arm assembly via a linkage assembly and adapted to move the moveable contact arm assembly to the open position upon detection of an overcurrent situation; a resetting mechanism, actuation of which is adapted to, when the moveable contact arm assembly is in the open position, move the moveable contact arm assembly to the closed position, the resetting mechanism extending from, or being accessible through, the outwardly facing exposed surface of the housing; and an arc splitter adapted to quench an arc created between the stationary contact and the moveable contact as the stationary contact and the moveable contact are moveable into and/or out of contact with one another; wherein said resetting mechanism comprises: a handle having a hole disposed therein, the hole formed in said handle cooperating with a pin about which the handle is pivotable; and a reinforcing insert operably connected to and pivotable with said handle, said reinforcing insert having a hole disposed therein, the hole formed in said reinforcing insert cooperating with the pin about which the handle is pivotable; a permanent magnet disposed on the moveable contact arm assembly, said permanent magnet disposed so as to urge an arc created between said stationary contact and said moveable contact toward said arc splitter; and wherein the linkage assembly comprises: a locking element, engagement of which causes said contact arm assembly to remain in the closed position when moved to the closed position by said resetting mechanism; and a pivotable rotator operably connected to the overcurrent tripping device such that upon detection of an overcurrent situation the overcurrent tripping device causes said rotator to pivot and consequently disengage said locking element, such that said contact arm assembly moves to the open position.

2. The circuit breaker of claim 1, wherein the housing has an outwardly facing exposed surface having a width and a height, wherein the width is greater than the height, and wherein the height is at most one-half inch.

3. The circuit breaker of claim 1, wherein said handle is formed from a polymer material and wherein said reinforcing insert is formed from a metal material.

4. The circuit breaker of claim 3 wherein the hole in the metal reinforcing insert inhibits elongation of the hole formed in the polymer handle.

5. The circuit breaker of claim 4 wherein the pin about which the polymer handle and metal reinforcing insert are pivotable is formed from a metal material, and wherein the hole in the metal reinforcing insert inhibits elongation of the hole formed in the polymer handle, whereby potential melting of the hole in the polymer handle caused by elevated temperature of the metal pin is inhibited.

6. The circuit breaker of claim 1 wherein said pivotable rotator is formed from a polymer material.

7. The circuit breaker of claim 1 wherein said permanent magnet is disposed on said moveable contact arm assembly at a location along the generally longitudinal axis between the moveable contact and a point at which said moveable contact arm assembly is pivotably connected with respect to said housing.

8. The circuit breaker of claim 1 wherein actuation of the resetting mechanism is further adapted to manually move the moveable contact arm assembly between the closed position and a second open position.

9. The circuit breaker of claim 8, wherein the handle has a portion thereof extending from the housing adapted to be actuated by a user.

10. The circuit breaker of claim 1 wherein the arc splitter comprises a plurality of spaced apart conductive plates disposed within the housing.

11. A circuit breaker comprising: a housing within which components of the circuit breaker are disposed; a line terminal adapted to be electrically connected to a source of electrical power; a load terminal adapted to be electrically connected to at least one load; a stationary contact positioned within the housing; a moveable contact arm assembly having a generally longitudinal axis and a moveable contact positioned thereon at a first end, the moveable contact arm assembly being pivotably mounted within said housing at a second end and being pivotable about the second end between a closed position in which the moveable contact and the stationary contact are in physical contact and the line terminal and the load terminal are in electrical communication, and an open position in which the moveable contact and the stationary contact are out of physical contact and the line terminal and the load terminal are out of electrical communication; an overcurrent tripping device operably coupled to the moveable contact arm assembly via a linkage assembly and adapted to move the moveable contact arm assembly to the open position upon detection of an overcurrent situation; a resetting mechanism, actuation of which is adapted to, when the moveable contact arm assembly is in the open position, move the moveable contact arm assembly to the closed position, the resetting mechanism extending from, or being accessible through, the outwardly facing exposed surface of the housing; and an arc splitter adapted to quench an arc created between the stationary contact and the moveable contact as the stationary contact and the moveable contact are moveable into and/or out of contact with one another; and wherein said resetting mechanism comprises: a handle having a hole disposed therein, the hole formed in said handle cooperating with a pin about which the handle is pivotable; and a reinforcing insert operably connected to and pivotable with said handle, said reinforcing insert having a hole disposed therein, the hole formed in said reinforcing insert cooperating with the pin about which the handle is pivotable.

12. The circuit breaker of claim 11, wherein the housing has an outwardly facing exposed surface having a width and a height, wherein the width is greater than the height, and wherein the height is at most one-half inch.

13. The circuit breaker of claim 11, wherein said handle is formed from a polymer material and wherein said reinforcing insert is formed from a metal material.

14. The circuit breaker of claim 13 wherein the hole in the metal reinforcing insert inhibits elongation of the hole formed in the polymer handle.

15. The circuit breaker of claim 14 wherein the pin about which the polymer handle and metal reinforcing insert are pivotable is formed from a metal material, and wherein the hole in the metal reinforcing insert inhibits elongation of the hole formed in the polymer handle, whereby potential melting of the hole in the polymer handle caused by elevated temperature of the metal pin is inhibited.

16. The circuit breaker of claim 11 further comprising a permanent magnet disposed on the moveable contact arm assembly, said permanent magnet disposed so as to urge an arc created between said stationary contact and said moveable contact toward said arc splitter.

17. The circuit breaker of claim 11 wherein the linkage assembly comprises: a locking element, engagement of which causes said contact arm assembly to remain in the closed position when moved to the closed position by said resetting mechanism; and a pivotable rotator operably connected to the overcurrent tripping device such that upon detection of an overcurrent situation the overcurrent tripping device causes said rotator to pivot and consequently disengage said locking element, such that said contact arm assembly moves to the open position.

18. A circuit breaker comprising: a housing within which components of the circuit breaker are disposed; a line terminal adapted to be electrically connected to a source of electrical power; a load terminal adapted to be electrically connected to at least one load; a stationary contact positioned within the housing; a moveable contact arm assembly having a generally longitudinal axis and a moveable contact positioned thereon at a first end, the moveable contact arm assembly being pivotably mounted within said housing at a second end and being pivotable about the second end between a closed position in which the moveable contact and the stationary contact are in physical contact and the line terminal and the load terminal are in electrical communication, and an open position in which the moveable contact and the stationary contact are out of physical contact and the line terminal and the load terminal are out of electrical communication; an overcurrent tripping device operably coupled to the moveable contact arm assembly via a linkage assembly and adapted to move the moveable contact arm assembly to the open position upon detection of an overcurrent situation; a resetting mechanism, actuation of which is adapted to, when the moveable contact arm assembly is in the open position, move the moveable contact arm assembly to the closed position, the resetting mechanism extending from, or being accessible through, the outwardly facing exposed surface of the housing; and an arc splitter adapted to quench an arc created between the stationary contact and the moveable contact as the stationary contact and the moveable contact are moveable into and/or out of contact with one another; and a permanent magnet disposed on the moveable contact arm assembly, said permanent magnet disposed so as to urge an arc created between said stationary contact and said moveable contact toward said arc splitter; wherein said permanent magnet is disposed on said moveable contact arm assembly at a location along the generally longitudinal axis between the moveable contact and a point at which said moveable contact arm assembly is pivotably connected with respect to said housing.

19. The circuit breaker of claim 18, wherein the housing has an outwardly facing exposed surface having a width and a height, wherein the width is greater than the height, and wherein the height is at most one-half inch.

20. The circuit breaker of claim 18 wherein said resetting mechanism comprises: a handle having a hole disposed therein, the hole formed in said handle cooperating with a pin about which the handle is pivotable; and a reinforcing insert operably connected to and pivotable with said handle, said reinforcing insert having a hole disposed therein, the hole formed in said reinforcing insert cooperating with the pin about which the handle is pivotable.

21. The circuit breaker of claim 18 wherein the linkage assembly comprises: a locking element, engagement of which causes said contact arm assembly to remain in the closed position when moved to the closed position by said resetting mechanism; and a pivotable rotator operably connected to the overcurrent tripping device such that upon detection of an overcurrent situation the overcurrent tripping device causes said rotator to pivot and consequently disengage said locking element, such that said contact arm assembly moves to the open position.

22. A circuit breaker comprising: a housing within which components of the circuit breaker are disposed; a line terminal adapted to be electrically connected to a source of electrical power; a load terminal adapted to be electrically connected to at least one load; a stationary contact positioned within the housing; a moveable contact arm assembly having a generally longitudinal axis and a moveable contact positioned thereon at a first end, the moveable contact arm assembly being pivotably mounted within said housing at a second end and being pivotable about the second end between a closed position in which the moveable contact and the stationary contact are in physical contact and the line terminal and the load terminal are in electrical communication, and an open position in which the moveable contact and the stationary contact are out of physical contact and the line terminal and the load terminal are out of electrical communication; an overcurrent tripping device operably coupled to the moveable contact arm assembly via a linkage assembly and adapted to move the moveable contact arm assembly to the open position upon detection of an overcurrent situation; a resetting mechanism, actuation of which is adapted to, when the moveable contact arm assembly is in the open position, move the moveable contact arm assembly to the closed position, the resetting mechanism extending from, or being accessible through, the outwardly facing exposed surface of the housing; and an arc splitter adapted to quench an arc created between the stationary contact and the moveable contact as the stationary contact and the moveable contact are moveable into and/or out of contact with one another; wherein the linkage assembly comprises: a locking element, engagement of which causes said contact arm assembly to remain in the closed position when moved to the closed position by said resetting mechanism; and a pivotable rotator operably connected to the overcurrent tripping device such that upon detection of an overcurrent situation the overcurrent tripping device causes said rotator to pivot and consequently disengage said locking element, such that said contact arm assembly moves to the open position; wherein said pivotable rotator is formed from a polymer material.

23. The circuit breaker of claim 22, wherein the housing has an outwardly facing exposed surface having a width and a height, wherein the width is greater than the height, and wherein the height is at most one-half inch.

24. The circuit breaker of claim 22 wherein said resetting mechanism comprises: a handle having a hole disposed therein, the hole formed in said handle cooperating with a pin about which the handle is pivotable; and a reinforcing insert operably connected to and pivotable with said handle, said reinforcing insert having a hole disposed therein, the hole formed in said reinforcing insert cooperating with the pin about which the handle is pivotable.

25. The circuit breaker of claim 22 further comprising a permanent magnet disposed on the moveable contact arm assembly, said permanent magnet disposed so as to urge an arc created between said stationary contact and said moveable contact toward said arc splitter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is a side isometric view illustrating the outside housing of an exemplary circuit breaker constructed in accordance with the present invention.

[0039] FIG. 2 is a side elevational view, partially broken away, of the exemplary circuit breaker constructed in accordance with the present invention as shown in FIG. 1, shown with the contacts in the closed position so that the circuit breaker is in an on state.

[0040] FIG. 3 is a side elevational view, partially broken away, of the exemplary circuit breaker constructed in accordance with the present invention as shown in FIGS. 1 and 2, shown with the contacts in the open position so that the circuit breaker is in an off state.

[0041] FIG. 4 is a side isometric view, partially broken away, of portions of the exemplary circuit breaker constructed in accordance with the present invention as shown in FIGS. 1-3, illustrating in greater detail certain aspects of the present invention, including the linkage mechanism and the moveable contact arm assembly thereof.

[0042] FIG. 5 is a side plan view of a portion of the exemplary circuit breaker constructed in accordance with the present invention as shown in FIGS. 1-4, illustrating in greater detail certain aspects of the present invention, including a handle reinforcing insert thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views.

[0044] FIG. 1 illustrates the exterior of an example circuit breaker (100) having an improved design that allows for the circuit breaker (100) to have a slim profile.

[0045] More specifically, circuit breaker (100) is provided with a housing (102) that contains the working elements of the device therein. The housing (102) has an exposed outwardly facing surface (104) that would remain visible to a user when the circuit breaker (100) is installed in a circuit breaker panel in a well-known manner. The housing (102) defines a depth (D) of the circuit breaker (100) (i.e., the extent to which the circuit breaker extends into the panel), a width (W) of the circuit breaker (100) (i.e., measured generally horizontally along the circuit breaker's exposed mounting surface in the typical orientation of a circuit breaker panel), and a height (H) of the circuit breaker (100) (i.e., measured generally vertically along the circuit breaker's exposed mounting surface in the typical orientation of a circuit breaker panel).

[0046] As discussed above, The present invention is specifically concerned with providing a slim design, wherein it is the height (H) of the circuit breaker (100) that is of particular concern. In particular, it is desired to limit the height (H) of the circuit breaker (100) to one-half inch (1.27 cm) or less, while at the same time still providing robust power (e.g., voltage) handling and arc interruption capabilities.

[0047] Referring now to FIGS. 2 and 3, the circuit breaker (100) is further provided with a set of contacts including a stationary contact (106) and movable contact (108). The moveable contact (108) is positioned on a moveable contact arm assembly (110), and the moveable contact (108) is configured to move between an open and closed position relative to the stationary contact (106). FIG. 2 shows the contacts (106, 108) in the closed position where electrical current flows therebetween, whereas FIG. 3 shows the contacts (106, 108) in the open position, where no electrical current flows therebetween.

[0048] Also shown in FIG. 1 is a “line” terminal (112), which is designed to be connected to a source of electrical power (not shown). Stationary contact (106) is mounted onto a first conductive element (114), which in turn is electrically connected to line terminal (112).

[0049] Also provided is a “load” terminal (116), which is designed to be connected to the electrical components (not shown) being fed from the circuit breaker, such as an individual component connected directly to a circuit breaker (e.g., an air conditioner unit), or multiple components through a power wire which terminates at electrical outlets.

[0050] Moveable contact (108) mounted on moveable contact arm assembly (110) is in indirect electrical communication with the load terminal (116). More specifically, the moveable contact arm assembly (110), which is electrically conductive, is in electrical communication with an input side of an overcurrent tripping device (118) through a conductive connector (120) via a not shown flexible conductive element, such as a braided wire, connected on one end to the moveable contact arm assembly (110) and on the other end to the conductive connected (120) (as is conventional). An output side of the overcurrent tripping device (118) is in electrical communication with a second conductive element (122) through a conductive connector (124), with the load terminal (116) being in electrical communication with the second conductive element (122).

[0051] In operation, and when the circuit breaker (100) is in the “on” state (i.e., when the stationary contact (106) and the moveable contact (108) are closed and thereby in electrical communication), electrical power is input into circuit breaker (100) via line terminal (112) and exits the circuit breaker (100) via the load terminal (116). The flow of electricity through the circuit breaker will now be discussed.

[0052] Electrical power flows into the circuit breaker (100) through line terminal (112), and then passes through first conductive element (114) to stationary contact (106). The contacts being closed, the electrical power flows through moveable contact (108), through conductive contact arm assembly (110), through conductive connector (120) and to the input side of overcurrent tripping device (118). The electrical power then flows out the output side of the overcurrent tripping device (118) through conductive connector (124), through second conductive element (122), exiting the circuit breaker through load terminal (116).

[0053] If the electrical current exceeds a threshold level, overcurrent tripping device (118) will function to “trip” the circuit breaker (100) by opening the circuit, opening the contacts relative to each other by means of a trip mechanism (126) (i.e., armature) and linkage assembly (128) such that the flow of electrical current through the contacts (106, 108) ceases. In the event that the electrical current does not exceed the threshold level set by overcurrent tripping device (118), the electrical power is allowed to pass through load terminal (116), which in turn, provides electrical power to the connected circuit and/or equipment.

[0054] The circuit breaker (100) also includes a resetting mechanism (130) adapted to reset the circuit breaker (100) and move the moveable contact (108) into physical contact with the stationary contact (106) by movement of the moveable contact arm assembly (110). The resetting mechanism (130) is connected to the linkage assembly (128), which in turn, is connected to the moveable contact arm assembly (110) for this purpose. The resetting mechanism (130) may also be used to manually open and close the contacts (106, 108), i.e., to turn the circuit breaker (100) on and off, as is known in the art. In the exemplary embodiment shown, the resetting mechanism (130) takes the form of a handle-type actuator, discussed in further detail below.

[0055] Referring again specifically to FIG. 2, the circuit breaker (100) is shown in the “on” position, where the contacts (106, 108) are closed. As is known, when the circuit breaker (100) is manually turned off or when an overcurrent situation is sensed, the contacts (106, 108) are caused to open, to thereby cease the flow of electrical power through the circuit breaker (100). However, also as is known, although moveable contact (108) has separated from stationary contact (106), electricity, in the form of an arc (not shown) may still flow from electrical contact (106) to electrical contact (108) for a period of time. The arc may be capable of jumping between electrical contacts, through air, and can cause severe damage to both contacts (106, 108).

[0056] In a worst case scenario, a single arc can damage the contacts so severely as to render them inoperable during normal operation. However, even when such is not the case, the arc may create heat (particularly, in the case of the present invention, where it is desired to provide a slimmer design than is typical, requiring a compact arrangement of parts), which may damage various components over time. To protect electrical contacts (106, 108), and circuit breaker (100) overall, any created arc must be extinguished as quickly as possible. This may be done by pushing the arc into an arc splitter (132) disposed within an arc chamber (134).

[0057] The arc splitter (132) may take the form of a plurality of spaced apart, generally metallic, plates which draw the arc in, and cool and quench the arc. Each plate may be spaced apart at the same distance, or the distance between each plate may vary depending on the application of circuit breaker. For example, each plate may be spaced apart approximately 0.8 inches from the next plate, or the distance between each plate (may be varied. For example, the plates toward one side of the housing may be closer together than the plates towards the other side of the housing, or vice versa.

[0058] Additionally, one or more arc straps (136) may be provided in order to provide a safe place for the arc to jump prior to the arc being fully extinguished. In the shown example, arc strap (136) is in electrical communication with the load terminal (116), although an arc strap in communication with the line terminal may be provided instead of, or in addition to, the illustrated arc strap (136).

[0059] As briefly noted above, the housing (102) of the circuit breaker (100) includes an outwardly facing exposed surface (104) through which the resetting mechanism (130) extends and/or is accessible by a user. As will be understood by those skilled in the art, circuit breakers of the type discussed herein are configured to be inserted into panels with a plurality of other circuit breaker (at least some of which are typically identical to others). A typical home, for example, has at least one, and perhaps two, three or even more, such panels, each of which may include 10, 20 or even more circuit breakers. Also as is understood by those skilled in the art, generally only one surface of each of the circuit breakers (i.e., the one carrying the resetting mechanism) is exposed. This outwardly facing exposed surface (shown as 104 in FIG. 1) generally defines at least one plane. Typically, all of the circuit breakers disposed in each panel have their outwardly facing exposed surface lying in the same plane.

[0060] As discussed, one of the objects of the present invention is to provide a circuit breaker design having a height (H), which is narrower than is typically achievable in circuit breakers of the type disclosed. The reason that the terms “height” is used herein is because circuit breakers are typically disposed in panels such that the line terminal (112) and the load terminal (116) are disposed generally horizontally, with multiple circuit breakers being stacked one on top of another such that the line terminals (112) of the stacked circuit breakers are generally vertically aligned and the load terminals (116) of the stacked circuit breakers are generally vertically aligned. With respect to the embodiment shown in FIGS. 1-3, this would mean that the handle-type actuator resetting mechanism (130) would be moveable horizontally left-to-right and right-to-left when facing the panel of circuit breakers. Typically, a panel for residential use includes two stacks of circuit breakers.

[0061] Preferably, the height (H) of the circuit breaker (100), including the outwardly facing exposed surface (104) is at most one-half inch (1.27 cm). While circuit breakers satisfying this height limitation are known, often these circuit breakers have heretofore been limited to relatively lower voltages. This is true because when components are made smaller to accommodate the reduced overall height of the circuit breaker, heat may become an issue unless the voltage handling capabilities are also reduced. An additional problem may be related to arc formation and, in particular, arc quenching, if the circuit breaker is made more compact, without also reducing the power handling capabilities of the circuit breaker. Ways in which the reduced height (H) of circuit breaker (100) can be achieved in accordance with the present invention, while still being able to employ such circuit breakers in connection with relatively higher voltages, will now be discussed.

[0062] Referring now specifically to FIG. 4, portions of the circuit breaker (100), including portions of the linkage assembly (128) and the moveable contact arm (110), are shown in greater detail with various portions being removed for clarity.

[0063] As shown, the linkage assembly (128) includes a number of conventional components which are very well known in the art, such that the configuration and operation thereof will not be discussed in detail. What is relevant to the present invention, however, is that the linkage assembly (128) includes a locking element (200), engagement of which causes the contact arm assembly (110) to remain in the closed position when moved to the closed position by the resetting mechanism (130). The linkage assembly also includes pivotable rotator (202) operably connected to the overcurrent tripping device (118) such that upon detection of an overcurrent situation the overcurrent tripping device (118) causes the rotator (202) to pivot and consequently disengage the locking element (200), such that the contact arm assembly (110) moves to the open position.

[0064] More specifically, the rotator (202) is pivotably connected at one end thereof (204) to the trip mechanism (126) portion of the overcurrent tripping device (118), while another end of the rotator (202) is provided with a hook-like member (206). Upon detection of an overcurrent situation the overcurrent tripping device (118) causes trip mechanism (126) to pivot, thereby causing corresponding pivoting of the rotator (202) via its cooperation with end (204), such that the hook-like member (206) is caused to disengage the locking element (200), such that the contact arm assembly (110) moves to the open position.

[0065] In order to at least partially insulate various components of the circuit breaker from one another, and in particular in order to inhibit heat from travelling freely across the entire linkage assembly (128), at least the rotator (202) is formed from a polymer material, such as polypropylene. It has been found that the rotator (202) is a good candidate to act as an insulating element within the linkage assembly (128), since the rotator (202) is not subjected to high stresses, in that it operates primarily to disengage the locking element (200) in the case of an overcurrent situation, which involves relatively low force transmission.

[0066] Also formed of a polymer material is the resetting mechanism (130), which is pivotably mounted with respect to the housing about a pin (138) (see FIGS. 2 and 3), which is typically metallic, so as to inhibit wear and provide the structural support required for resetting mechanism (130). However, it has been found that when providing the desired slim features in conjunction with relatively higher voltages, heat transmitted to the pin (138) may cause elongation of the pin-receiving hole (140) (see FIG. 4) provided in resetting mechanism (130), due to melting and/or thermal runaway.

[0067] In order to mitigate these issues, the resetting mechanism (130) is provided with at least one reinforcing insert (142), as best seen in FIGS. 2 and 5. The reinforcing insert (142), which is operably connected to and is pivotable with the resetting mechanism (130), includes a hole (300) disposed therein. The hole (300) in the reinforcing insert (142) is aligned with the pin-receiving hole (140) provided in the resetting mechanism (130), and is sized to pivotably engage the pin (138) about which the resetting mechanism (130) is pivotable in a known manner. The reinforcing insert (142) is formed from a metal material, such that potential melting of the hole (140) formed in the polymer resetting mechanism (130) caused by elevated temperature of the metal pin (138) is inhibited.

[0068] The creation of heat is further mitigated by aiding in the quenching of any created arcs as quicky as possible. This is achieved in accordance with the present invention by the provision of a permanent magnet (144) to aid in urging the arc toward the arc splitter (132). While the use of permanent magnets for this purpose is well-known (such that the principles of operation behind their use is not discussed in detail herein), the present invention distinguishes itself from heretofore known designs by positioning the permanent magnet (144) on the moveable contact arm assembly (110). In particular, the permanent magnet (144) is disposed on the moveable contact arm assembly (110) at a location along a generally longitudinal axis of the contact arm assembly (110) between the moveable contact (108) and a point (146) at which the moveable contact arm assembly (110) is pivotably connected with respect to said housing (102).

[0069] Thus, with this placement of the permanent magnet (144), as the moveable contact arm assembly (110) opens toward the arc splitter (132), with any created arc also consequently moving toward the arc splitter (132), the moveable permanent magnet (144) also moves toward the arc splitter (132), along with the arc. This movement of the permanent magnet (144) in the same direction as the arc means that the relative distance between the permanent magnet (144) and the arc remains smaller than it would if the permanent magnet was stationary for the entire travel of the arc, resulting in a greater force urging the arc toward the arc splitter (132), since the magnitude of the force of the magnet on the arc is directly related to the distance between the magnet and the arc. As such, arc quenching is enhanced.

[0070] Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.