Limit stop apparatus, circuit breakers including limit stops, and methods of using same

A limit stop apparatus for a multi-pole electrical contact assembly is disclosed. The limit stop apparatus interconnects crossbars of respective contact assemblies wherein one or more contact arms are pivotable relative to each crossbar. The limit stop apparatus is configured to engage the one or more contact arms on a same side of the one or more contact arms containing moveable electrical contacts. In one or more embodiments, the limit stop apparatus has a connecting bar with limit stops having arc shields molded to the connecting bar, wherein the arc shields can be phase-to-phase arc shields and contact-to-component arc shields. Circuit breakers and multi-pole electrical contact assemblies having a limit stop apparatus, and methods of operating the multi-pole electrical contact assembly are disclosed, as are other aspects.

RELATED APPLICATIONS

This application claims priority to PCT Application Serial Number PCT/US2011/024016 filed on Feb. 8, 2011, entitled “CIRCUIT BREAKER ELECTRICAL CONTACT ASSEMBLY, AND SYSTEMS AND METHODS USING SAME” the disclosure of which is hereby incorporated by reference in its entirety herein.

FIELD

The present invention relates generally to circuit breakers, and more particularly to apparatus adapted to limit rotation of components used in circuit breakers.

BACKGROUND

Within circuit breakers, one or moveable electrical contacts may be provided. Typically, such moveable electrical contacts are included on moveable contact arms that pivot relative to a circuit breaker housing. Generally, a spring biases the moveable contact to a closed configuration such that intimate contact is provided between a stationary and moveable electrical contact. Some circuit breakers may include multiple interconnected contact assemblies. For example, a single electrical phase may be directed and coupled to individual side-by-side electrical contact assemblies of a multi-phase circuit breaker. Three or four phase breaker assemblies are commonplace. Each electrical contact assembly may be connected to adjacent ones through a cross member, and each of the side-by-side electrical contact assemblies is adapted to pivot about a common pivot axis.

However, existing pivoting constructions may lead to certain design compromises. Thus, improved pivoting apparatus adapted to use in side-by-side electrical contact assemblies are sought.

SUMMARY

In a first embodiment, a limit stop apparatus is provided. The limit stop apparatus includes a connecting bar, and arc shields molded to the connecting bar, the arc shields comprising phase-to-phase arc shields and contact-to-component arc shields.

In a system embodiment, a multi-pole electrical contact assembly is provided. The multi-pole electrical contact assembly includes a plurality of electrical contact assemblies, each electrical contact assembly having a crossbar and one or more contact arms pivotable relative to the crossbar, and a limit stop apparatus coupled to the crossbar of each electrical contact assembly, wherein the limit stop apparatus has limit stops configured and adapted to engage the one or more contact arms on a same side of the one or more contact arms containing moveable electrical contacts.

In another apparatus embodiment, a circuit, breaker is provided. The circuit breaker includes a circuit breaker housing, a plurality of electrical contact assemblies, each electrical contact assembly having a crossbar and one or more contact arms moveable relative to the crossbar, and a limit stop apparatus coupled to the crossbars of each of the plurality of electrical contact assemblies, wherein the limit stop apparatus has limit stops configured and adapted to engage the one or more contact arms on a same side of the one or more contact arms containing moveable electrical contacts.

In a method aspect, a method of operating a multi-pole electrical contact assembly is provided. The method includes providing a plurality of electrical contact assemblies, each electrical contact assembly having a crossbar and one or more contact arms having one or more moveable electrical contacts pivotable relative to the crossbar, and a limit stop apparatus having limit stops, the limit stop apparatus coupled to and interconnecting to the crossbar of each electrical contact assembly, and engaging with the limit stop apparatus, the one or more contact arms on a same side of the one or more contact arms containing the one or more moveable electrical contacts.

Still other aspects, features, and advantages of the present invention may be readily apparent from the following detailed description by illustrating a number of example embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention may also be capable of other and different embodiments, and its several details may be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. The invention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention.

DESCRIPTION

In view of the foregoing difficulties, an improved limit stop apparatus is provided, as well as an electrical contact assembly including the limit stop apparatus. In another aspect, a circuit breaker including the improved limit stop apparatus and multi-pole electrical contact assembly is provided. Methods of operating a multi-pole electrical contact assembly including the limit stop apparatus are also provided.

As will become apparent from the various embodiments, the limit stop apparatus has limit stops that advantageously limit motion of the one or more contact arms of the individual contact assemblies. The limit stop functions to tie the individual electrical contact assemblies together such that the crossbars thereof move in unison, such as when a circuit breaker handle is actuated. Furthermore, the limit stop apparatus may include arc shields that function to limit exposure of the internal contact assembly components to arcing and arc debris upon encountering an interruption event (e.g., after breaker tripping).

These and other embodiments of the limit stop apparatus, multi-pole electrical contact assembly, circuit breakers including a multi-pole electrical contact assembly and methods of operating multi-pole electrical contact assemblies are described below with reference toFIGS. 1A-1B. The drawings are not necessarily drawn to scale. Like numerals are used throughout to denote like elements.

Referring now in specific detail toFIGS. 1A-1B, a limit stop apparatus100is shown. The limit stop apparatus100is a part of a multi-pole contact assembly300(FIG. 3) that may be installed in a circuit breaker housing660of a circuit breaker700, as shown inFIGS. 7-10, for example. The limit stop apparatus100may perform multiple functions within the circuit breaker700, and is functionally coupled to, and interconnects, individual contact assemblies200(FIG. 2) with one another. In order to understand the function of the limit stop apparatus100, the electrical contact assembly200will first be described.

Referring now in specific detail toFIG. 2toFIG. 5B, an embodiment of the electrical contact assembly200and its components are shown. The electrical contact assembly200will be referred to herein as an “electrical contact assembly,” “contact assembly,” or just “assembly.” The contact assembly200may be installed in a circuit breaker housing660of a circuit breaker700, as shown inFIGS. 6A-10, for example. As depicted, the circuit breaker700may include multiple individual contact assemblies200(e.g., one for each electrical phase). For example, a multi-pole contact assembly300may be included in a three-pole circuit breaker (SeeFIGS. 3 and 8) and may include three electrical contact assemblies200oriented in a side-by side configuration.

Again referring toFIGS. 2-5B, each electrical contact assembly200may be interconnected to a respective load terminal (e.g., a single phase) via one or more flexible electrical conductors501(FIG. 5A). In some embodiments, the flexible electrical conductor501may be one or more braided or laminated conductive metal lines. The flexible electrical conductor501may be connected to each of the contact arms206(described below), such as by braising, welding, soldering, or the like. Other means for connection may be employed. The contact assembly200may include one or more contact arms206.

Referring to FIGS.2and4A-4B, the electrical contact assembly200may include a body structure such as a crossbar202, a pivot pin204mounted in the crossbar202, and one or more contact arms206pivotally mounted on the pivot pin204and rotatable about a first pivot axis207extending along a length of the pivot pin204. The pivot pin204may be manufactured from a rigid material, such as steel. Other rigid materials may be used. In some embodiments, the pivot pin204may be a rivet. In the depicted embodiment, pivotal attachment of the contact assembly200to a circuit breaker housing660of a circuit breaker700, as shown inFIGS. 9 and 10, may be about a second pivot axis208. The crossbar202may function as a body to enable the pivotal attachment of the contact assembly200relative to a circuit breaker housing660, such as shown inFIGS. 6A-6D, andFIGS. 9 and 10. Pivoting rotation of the contact assembly200about the second pivot axis208may be provided by pilots213extending laterally from either side of the crossbar202and rotationally received within holes570A,570B in a bracket315(FIGS. 3 and 5B).

The crossbar202may be manufactured from a suitably rigid material, such as a filled plastic or a metal (e.g., steel) sheet, and may include generally parallel first and second sidewalls202A,202B and a pocket202C. In the depicted embodiment, the pivot, pin204may extend between the first and second sidewalls202A,202B. Furthermore, in the depicted embodiment, the multiple contact arms206are pivotally mounted on the pin204in a side-by-side orientation wherein the pin204passes through apertures215. Suitable spacers (e.g., bosses on each arm206) may maintain a proper spacing between the respective contact arms206such that they may rotate freely thereon. Mounted on each of the contact arms206, such as on a first arm portion thereof, is a moveable electrical contact209M. The moveable electrical contact209M is spaced from the first pivot axis207on the first arm portion by a first distance. The first distance may be between about 40 mm and 60 mm, and about 54 mm in some embodiments, for example. Other first distances may be used.

Pivotally coupled to a second arm portion of each contact arm206, is a spring assembly210. The spring assembly210pivotally connects to the second arm portion by a pivoting connector at a connection location that is spaced a second distance from the first pivot axis207. The second distance may be between about 15 and 25 mm, and about 19 mm in some embodiments, for example. Other distances may be used. Generally, the second distance is less than the first distance. Furthermore, the second arm portion of the contact arm206may be located on an opposite side of the pivot axis207from the first arm portion of the contact arm206.

In some embodiments, the spring assembly210may comprise a strut. The spring assembly210is coupled between the crossbar202and the second arm portion of the contact arm206. The spring assembly210may include, as shown inFIGS. 4A-4B, a clevis pin212, and a spring214received on the clevis pin212. The clevis pin212may be a cylindrical pin including an end portion212A that is configured and adapted to be received and pivot relative to the crossbar202.

In some embodiments, the crossbar202may include a crossbar insert216(FIGS. 4A-4B,5A and6D). In the depicted embodiment, each of the spring assemblies210couples to the crossbar202via the crossbar insert216. Crossbar insert216may be received in the pocket202C of the crossbar202or otherwise retained for rotation therein. In some embodiments, the crossbar216may be fastened by screws in the pocket202C. The crossbar insert216may be a cast metal, such as steel, for example. A representative crossbar insert216is shown in cross section inFIGS. 4A-4B. Another crossbar insert is shown inFIG. 5A. The crossbar insert216is adapted to receive the ends212A of the clevis pins212of spring assemblies210. As should be understood, electrical contact assemblies200having any number of spring assemblies therein, such as one, two, three, four, five, or more may be provided. Each respective spring assembly210engages the crossbar insert216.

Specifically, each clevis pin212may be received in a pivot recess218formed in the crossbar insert216, for example. The pivot recess218may be oversized (e.g., larger in dimension) as compared to an outside dimension of the clevis pin212at the end212A. For example, the clevis pin212may include a diameter of the cylindrical portion of between about 3 mm and 8 mm, or even about 3 mm and 5 mm, and may be about 4 mm in some embodiments. Other diameters may be used. In some embodiments, the pivot recess218may be elongated in one direction, such as along a direction of pivot of the clevis pin212in the crossbar insert216. The elongation provides a larger dimension than the end of the clevis pin212along the direction of pivoting, as compared to the dimension perpendicular thereto, which may be only slightly larger than the end212A of the clevis pin212. The pivoting results from tripping of the contact assembly200from a closed (ON) configuration (FIG. 6A) to an open (OFF) configuration (seeFIG. 6B).

To minimize restriction (e.g., friction) due to pivoting resistance of the spring assembly210relative to the crossbar insert216as the spring assembly210pivots from the closed (FIG. 6A) to the open configuration (FIG. 6B), a curved or pointed surface216A may be included on a portion of the crossbar insert216contacted by the spring214(SeeFIG. 6D). The surface of the crossbar insert216may also include lubrication or other low friction surface treatment thereon. In some embodiments, the structure of the crossbar insert216may be integral with the crossbar202. In the case of a pointed ridge, the ridge may extend along the transverse width of the crossbar insert216. The pointed ridge may be formed by the intersection of two planes formed on upper and lower sides of the front surface of the crossbar insert216. A small radius may be provided on the ridge.

As best shown inFIGS. 4A-4B, the spring assembly210may include a spring retainer219in contact with a first end of the spring214. The spring retainer219may be a separate component or part of the pivoting connector of the spring assembly210, such as part of a clevis220(FIG. 4B) or rod end228(FIG. 4A). In the depicted embodiment, the spring214may be a helical coil spring. The spring214may have a spring constant (K) of between about 8 and 75 N/mm, for example. The spring214may have a length between about 30 mm and 50 mm, for example. The outer diameter of the helical coil spring214may be between about 6 mm and 14 mm, for example. The wire diameter of the spring214may be between about 1 mm and 3 mm. Other spring stiffnesses, lengths, outer diameters, and wire diameters may be used.

Other types of springs214may be used and received over the clevis pin112, such as conical springs, bellville washers, volute spring, wave springs, dome springs, or the like. Table 1 below outlines various coil springs that may be used for several designs. However, in some embodiments different spring constants may be used. As will be described below, certain attachments of the rod end228to the second arm portion of the contact arm206may allow for use of slightly larger spring diameters. In some embodiments, use of larger springs may improve the withstand rating (maximum short time current the circuit breaker can withstand without opening the contacts) of the circuit breaker700.

In some embodiments, as is shown inFIG. 4B, a first end of the spring assembly210may include a pivoting connector comprising a clevis220that is pivotally coupled to a terminal end of a second arm portion of the contact arm206. The pivoting connection may be accomplished by passing a cross pin222through apertures formed in each side of the clevis220and through a hole formed at the terminal end of the second end portion of the contact arm206. The cross pin222may be of any suitable configuration. For example, in some embodiments, the cross pin222may be a steel rivet. Cross pin222may be suitably press fit into clevis220. In some embodiments, the cross pin220may include a head. In embodiments, a low friction pivot connection is formed at the first end by the pin222received in the pivoting connector and in the hole formed in the contact arm206. Other pivoting connections may be used.

In the depicted embodiment ofFIG. 4B, the spring retainer219comprises the portion of the clevis220that connects the respective sides of the clevis220. The dimension of the spring retainer219in each embodiment should be sufficient to allow the spring214to be suitably compressed between crossbar insert216and the spring retainer219upon installation. In some embodiments, a contact surface area of the spring retainer219in contact with the spring214may be at least as large as the end of the spring214. The spring retainer219may comprise a planar surface contacting the first end of the spring214. The diameter of the clevis pin212should be sufficient to minimize any buckling of the spring214in the as-compressed condition. As installed, the spring214may be pre-compressed between the surface of the spring retainer219and the crossbar insert216sufficiently to provide a contact force between the stationary contact209S and the moving contact209M of between about 25 N and 120 N, for example. Other contact forces may be used.

In an alternate embodiment, the spring assembly210may include a pivoting connector comprising a rod end228pivotally coupled to a terminal end of a second arm portion of the contact arm206with a cross pin222as is shown inFIG. 4A. The rod end228may be coupled directly to the spring retainer219. In some embodiments, the rod end228can be integral with the spring retainer219. Rod end228includes a rigid hoop of material surrounding a hole that receives the cross pin222. However, the spring retainer219and rod end228may be separate components in some embodiments.

To reduce an overall width of the contact assembly200, combinations of spring assemblies210having pivoting connectors of one or more rod ends228and one or more clevises220may be provided. For example, the outer two spring assemblies210may include pivoting connectors that are rod ends228, whereas the center spring assembly may include a pivoting connector that is a clevis220. Any combination of rod ends228and clevises220may be utilized.

In the depicted embodiment ofFIG. 5A, each of the spring assemblies210includes rod ends228that are laterally offset from a centerline of the clevis pin212. Each rod end228includes an offset configuration wherein the hoop of the rod end228is offset laterally from an axial centerline of the clevis pin212. This allows the spring assembly210to be mounted to the contact arms206in a number of different configurations. Such lateral offsets may allow for larger springs214to be used, while keeping the spacing between the contact arms206small. Larger springs can provide greater contact forces. Cross pins222are inserted through the offset rod ends228and may be peened for retention. The springs214may be pre-compressed between the crossbar insert216and the integral spring retainers219. Arc horns240may be provided on the ends of the contact arms206opposite the moveable contacts209M.

Again referring toFIGS. 1-3, individual contact assemblies200may be assembled into a multi-pole contact assembly300. In the depicted embodiment, the contact assemblies200are identical to one another, and each one is adapted to receive a single electrical phase provided from a polyphase electrical power distribution system (not shown). A three-phase contact assembly300is shown, but various embodiments are equally adapted for use with four-phase systems, five-phase systems, or the like. Each of the individual contact assemblies200may be pivotally mounted to the circuit breaker housing660(FIG. 6A-6D) by the bracket315(FIG. 3), as is described further herein. The limit stop apparatus100may be provided underneath the contact arms206and include limit stops102,103,104engageable with the one or more contact arms206of each contact assembly200(FIGS. 3,6A-6D, and8-10).

In operation, the limit stop apparatus100includes limits stops102,103,104that are engageable with the contact arms206on a same side of the contact arms206containing the moveable contact209M between the first pivot axis207and the moveable contacts209M. Providing the limit stop apparatus100including limit stops102,103,104under the contact arm206may allow for a lower overall profile height of the contact assembly300. The limit stop apparatus100may limit a motion of the spring assemblies210and rotation of contact arms206. For example, the limit stop apparatus can allow all electrical phases to be opened or closed simultaneously by operating the handle725of the circuit breaker700(FIG. 7). At other times, the limits stops102,103,104rest against the contact arms206and prevent the contact arms206from pivoting beyond an intended range. For example, the limit stop apparatus100may be rotated into the OFF position a short delay time after a tripping event, by a tripping device. The pivot stop apparatus100may prevent the contact arms206from over rotation due to contact erosion due to mechanical wear or fatigue, for example. Additionally or alternatively, the limit stop apparatus100may include features that function as a barrier wall or shield to minimize arcing between adjacent phases from the separation of the electrical contacts209M,209S of each phase, but also to minimize an extent of spray of arcing debris onto contact, assembly components or between the phases.

As best shown inFIG. 9, the limit stop apparatus100is attached to a front, end of the crossbar202facing the stationary and moveable electrical contacts209S,209M and functions as a shield that prevents arcing debris from separation of the electrical contacts209S,209M from each phase from entering into respective separated areas855A,855B,855C of the circuit breaker housing760from each of the respective arc chambers858A,858B, and858C.

As best depicted inFIGS. 1C and 1Dthe limit stop apparatus100may include a reinforcing connecting bar101, which may be manufactured from a nonferrous material. Suitably rigid nonferrous materials comprise a reinforcing steel rod such as a stainless steel rod. Other suitably rigid, electrically-nonconductive materials may be used, such as filled plastics. The connecting bar101may be about 7 mm tall×7 mm wide×180 mm long and may extend across a lateral width of the circuit breaker housing660. In some embodiments, the connecting bar101may include a chamfer along an entire length of one or more edges, for example. Other sizes and shapes may be used.

In the depicted embodiment, the remaining portion of the limit stop apparatus100(that is not the connecting bar101) and the limit stops may be manufactured from a moldable material. Thus, a limit stop apparatus100including integrated limit stops102,103,104and arc shields may be formed. Suitable molded materials comprise plastic (e.g., a thermoplastic), such as the plastic used, for the circuit breaker housing660, rubber, or the like. A suitable material is fiberglass-filled polyester. The connecting bar101(e.g., reinforcing steel rod) may be received through all of the limit stops102,103,104and connector portions105, and in some embodiments may be bonded thereto. A skin of molded material should cover all portions of the connecting bar101. The skin thickness may be greater than about 1 mm. In some embodiments, the skin thickness may be between about 1 mm to about 5 mm, or even between about 1.5 mm to about 3 mm.

The limit stop apparatus100may include one or more arc shields. The one or more arc shields may be molded, such as by an injection molding process. For example, in the depicted embodiment, the arc shields may comprise contact-to-components arc shields102A,103A,104A embodied in the limit stops102,103,104that are spaced laterally from one another and may be molded to, interconnected, and/or structurally reinforced (e.g., stiffened) by the connecting bar101. The contact-to-components arc shields102A,103A,104A may be provided with a curved frontal surface on each of the limit stops102,103,104facing the moveable contacts209M. The curved surfaces may closely mesh with a similar curved surface (e.g., curved surfaces660B,660C) formed on the circuit breaker housing660(FIGS. 6A-6D) for each phase. For example, a small gap (e.g., approx. 0.5 mm) may be provided between the curved frontal surface of contact-to-components arc shield104A and the curved surface660C. Similar gaps may be provided between arc shield103A and the curved surface660B and between the arc shield102A and the curved surface on the circuit, breaker housing660for the first phase. Other sized gaps may be used.

Again referring toFIG. 1A-1B, each of the limit stops102,103,104may include upper projections109A and lower projections109B extending from a side of each limit stop102,103,104facing the tabs232. The projections109A,109B may function to allow ease of assembly by registering on the tabs232.

In an ON configuration (seeFIG. 6A) the curved frontal surface of the contact-to-components arc shield104A of the limit stop104is received proximate to a surface (e.g., curved surface660C) of the circuit breaker housing660(only a portion shown). Upon tripping or opening, the curved frontal surface of the contact-to-components arc shield104A moves (e.g., rotates) relative to the stationary surface660C of the circuit breaker housing660. The contact-to-components arc shield104A and the curved surface660C may still slightly overlap at the maximum rotational excursion of the crossbar202. The contact-to-components arc shields102A,103A,104A effectively form a barrier wall or shield for each electrical phase that may operatively minimize arc debris from exiting each respective arc chamber858A-858C (FIG. 8) of the circuit breaker housing660. In particular, the cooperation of the curved surfaces660A,660B,660C of the circuit breaker housing660and the contact-to-components arc shields102A,103A,104A are particular effective at limiting arc spatter.

Referring toFIGS. 8 and 9, each of the arc chambers858A-858C may include the stationary electrical contact209S, and an arc plate assembly959(FIG. 9). Arc plate assemblies are not shown inFIG. 8. Thus, splattering of debris may be minimized into a respective separated chamber855A-855C containing the other contact assembly components of each of the contact assemblies200(e.g., pivoting connectors, spring assemblies210, brackets500, or the like). Such arc debris, may over time impact the smooth tripping action of the circuit breaker700. Minimization of the travel of such arcing debris splatter is desired. Thus, the contact-to-components arc shields102A,103A,104A of the limit stops102,103,104function to block splattering of arc debris generated by the separation of the moving and stationary electrical contacts209M,209S from traveling from the respective arc chambers858A-858C to the respective separated chambers855A-855C where the various contact assembly components reside.

Again referring toFIGS. 1A-1B, the limit stop apparatus100may also include, for example, formed as a molded projection, an interlock interface110. The interlock interface110may extend from the back side of the limit stop apparatus100and function to interface with a plunger to allow interlock of two adjacent circuit breakers.

Referring toFIGS. 1A-1B,1D,FIGS. 6A-6D, andFIG. 8, the arc shields may comprise phase-to-phase arc shields106,107that are spaced laterally along a length of the limit stop apparatus100and integral with the limit stops102,103,104of the limit stop apparatus100. The phase-to-phase arc shields106,107may include planar surfaces106A,107A that interface with openings in walls865A,665B of the circuit breaker housing660(FIG. 8) that separate the respective electrical phases. In the depicted embodiment, the phase-to-phase arc shields106,107are shown molded to the connecting bar101on an inner end of the outermost limit stops102,104. However, additionally, or alternatively, they may be molded on the ends of the center limit stop103. Each of the phase-to-phase arc shields106,107may include stiffening portions106A,107A that are adapted to reinforce and limit lateral flexing of the phase-to-phase arc shields106,107. Stiffening portions106A,107A may be rib areas of the molding that are thicker.

Each of the phase-to-phase arc shields106,107may be shaped and sized so that the openings in the walls865A,865B are covered regardless of the position of the limit stop apparatus100. As installed, the connecting portions105are received in the openings of the walls865A,865B. Accordingly, the limit stop apparatus100in some embodiments provides a single component that interconnects the contact assemblies200, and also includes integrated arc shields that shield rearward spray of arc debris towards the respective contact components, and also minimizes phase-to-phase arcing. The limit stop apparatus100is sufficiently rigid to transfer the load from operation of the handle725of the circuit breaker700connected to the handle assembly1090(FIG. 10) to simultaneously move each of the interconnected contact assemblies200such that all electrical phases may be simultaneously actuated.

In the depicted embodiment ofFIG. 8, a first electrical phase and the components thereof is received and operable in arc chamber858A and separated chamber855A. A second electrical phase and the components thereof are received and operable in arc chamber858B and separated chamber855B. A third electrical phase and the components thereof are received and operable in arc chamber858C and separated chamber855C.

FIGS. 3 and 8illustrates the limit stop apparatus100for a three-pole circuit breaker700wherein the three contact assemblies200(seeFIG. 2) are coupled together by the limit stop apparatus100. Thus, the crossbars202all rotate in unison. The limit stop apparatus100may be coupled to the respective crossbar202by mounting features. For example, fasteners311(e.g., screws, bolts, rivets or the like) may be received through holes108(FIG. 1A) and coupled (e.g., by threaded nuts) to tabs232formed on the sides of crossbars202(FIG. 2). Tabs232may include captured or welded nuts.

In operation, when a tripping event occurs, such as due to a current over the rated current of the phase, rotation of the moveable contact arms206occurs. This causes the contact arms206to rapidly rotate and move from a closed (ON) configuration (FIG. 6A) to a blown open configuration (FIGS. 6C and 6D). Initially (in the closed configuration), a force vector is oriented and directed from the crossbar insert216through the spring214and spring retainer219to the pivoting connection location of the spring assembly210to the second arm portion of contact arm206. This force vector is provided on a first side of the pivot axis207. Accordingly, action of the spring assembly210provides a spring force to maintain the moveable and stationary contacts209S,209M in intimate contact and under suitable contact pressure. Upon tripping, the force vector crosses over the pivot axis207as the contact arm206moves from a closed configuration to an open configuration (FIG. 6C). In the opened configuration, as shown inFIG. 6C, the force vector extends from the crossbar insert216through the spring214and spring retainer219and through the connection of the spring assembly210to the contact arm portion, and the force vector is now provided on the opposite side of the pivot axis207. Accordingly, the spring force provided by the spring assembly210now holds the contact arms206in an open configuration. A short duration after a trip is experienced, an actuator (not shown) may rotate the assembly of crossbars202and limit stop apparatus100into a position as shown inFIG. 6B.

Resetting of the contact arms206to a closed configuration (e.g.,FIG. 6A) may be provided by any suitable mechanical mechanism1090contacting the one or more contact arms206or crossbars202to cause the one or more arms206to move back to the closed configuration.

FIGS. 6A-10illustrates a circuit breaker700including a circuit breaker housing660that receives a plurality of electrical contact assemblies200therein. As best shown inFIGS. 6A-6D, each of the contact assemblies200may be pivotally attached to the housing660by the bracket315(FIG. 5B). Bracket315includes holes570A,570B that are received over pilots213. Pilots213allow the respective contact assemblies200to pivot relative to the bracket315, and, thus, the breaker housing660.

FIG. 10illustrates some additional components of the circuit breaker700, such as arc plate stack959and handle assembly1090adapted to reset the circuit breaker700after a tripping event to the “ON” configuration or otherwise turn the circuit breaker700to the “OFF” configuration.

FIG. 11is a flowchart illustrating a method of operating a multi-pole electrical contact assembly (e.g.,300) according to embodiments. The method1100includes, in1102, providing a plurality of electrical contact assemblies (e.g., contact assemblies200), each electrical contact assembly having a crossbar (e.g., crossbar202) and one or more contact arms (e.g., contact arms206) having one or more moveable electrical contacts (e.g., moveable electrical contacts209M) moveable relative to the crossbar, and a limit stop apparatus (e.g., limit stop apparatus100) coupled to and interconnecting the crossbar of each electrical contact assembly. In1104, the limit stop apparatus engages the one or more contact arms on a same side of the one or more contact arms containing the one or more moveable electrical contacts. In some embodiment, the limit stop apparatus100is positioned very close to the moveable contact209M and engages the one or more contact arms between the moveable contacts209M and the first pivot axis207.

According to alternative or additional embodiments as shown inFIG. 12, a method1200of operating a multi-pole electrical contact assembly (e.g., multi-pole electrical contact assembly300) includes, in1202, providing arc chambers (e.g.,858A-858C) in a circuit breaker housing (e.g., circuit breaker housing660) adjacent to the one or more moveable electrical contacts (e.g., moveable electrical contacts209M) for each respective electrical contact assembly (e.g., contact assemblies200). The method1200, in1204, also includes minimizing arc debris from exiting the respective arc chambers of the circuit breaker housing by shielding arc debris with contact-to-component arc shields (102A,102B,102C) formed on the limit stop apparatus (e.g., limit stop apparatus100). In particular, the contact-to-component arc shields102A,103A,104A may be integral to and molded with the limit stops102,103, and104.

According to another alternative or additional embodiment as shown inFIG. 13, a method1300of operating a multi-pole electrical contact assembly (e.g., multi-pole electrical contact assembly300) includes, in1302, providing arc chambers (e.g.,858A-858C) in a circuit breaker housing (e.g., circuit breaker housing660) adjacent to the one or more moveable electrical contacts (e.g., moveable electrical contacts209M) for each respective electrical contact assembly (e.g., contact assemblies200). The method1300, in1304, also includes minimizing arcing arc between adjacent phases of the circuit breaker housing by shielding with phase-to phase arc shields (e.g., phase-to-phase arc shields106,107) on the limit stop apparatus (e.g., limit stop apparatus100) that are moveable relative to a wall (e.g., walls865A,865B) of the circuit breaker housing separating respective phases of the circuit breaker housing. The with phase-to phase arc shields (e.g., phase-to-phase arc shields106,107) may prevent arc debris from exiting one phase and traveling to an adjacent phase of the circuit breaker housing by shielding the arc debris with phase-to phase arc shields.

While the invention is susceptible to various modifications and alternative forms, specific embodiments and methods thereof have been shown by way of example in the drawings and are described in detail herein. It should be understood, however, that it is not intended to limit the invention to the particular apparatus, systems, or methods disclosed, but, to the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention.