The present disclosure relates generally to power distribution devices and systems and, more particularly, to connectors for electrically coupling circuit breakers to power bus bars or for making other electrical connections.
Circuit breakers are most commonly used to protect electrical equipment from overload and short circuit events. Large circuit breakers that carry thousands of amps of current are oftentimes installed into metal-enclosed switchgear assemblies, which are also referred to as “switchboards.” Switchgear assemblies have large electrical conductors called bus bars (or “buss bars”) that transmit current from a power source, such as a power utility, through the circuit breakers, to loads that are protected by the circuit breaker. These large circuit breakers, which can weigh hundreds of pounds, are typically lifted into the switchgear and racked by mounting the circuit breakers into a drawout cradle. A manually controlled or remotely operated mechanism is typically utilized to crank the drawout cradle and rack the circuit breaker into the switchgear and complete an electrical circuit which is protected by the breaker.
On the backs of these large circuit breakers facing the rear interior of the switchgear cabinet are connection members, such as bus bars, with elongated cluster supports that have pivots which jut out. Onto these pivots are installed multiple “clusters,” which are electrical connectors that have opposing stacks of plate-like fingers. These fingers straddle the pivots and allow the clusters to adapt their positions to engage bus bar connectors, such as fixed stab terminals (“stabs”) or turnable joint mount (TJM) connectors, which are housed inside the switchgear cabinets, for example, for a blind rack-in connection. These fingers are biased by spring elements to stay on the pivots so that the cluster “snaps” onto the pivot. It is important that these clusters remain secured on the pivots because if they become loose or dislodged as the circuit breaker is being racked into the switchgear or during operation of the switchgear, a cross-phase connection or a short circuit from an electrical phase to ground can occur.
The switchgear assembly typically comprises a cabinet that houses a drawout circuit breaker cradle for receiving and supporting the circuit breaker. The drawout cradle simplifies mounting and dismounting of the circuit breaker from field serviceable connections, allowing for ease of installation, removal, and maintenance. At the distal end of the cabinet on the opposite side of the opening through which the circuit breaker is received is a breaker backmold, which is often made from a rigid thermoset material, such as a phenolic resin, and used as a mounting interface. For instance, the backmold attaches to the circuit breaker cradle and provides a mounting surface for current transformers, metering transformers, and the power connectors (e.g., stabs or TJMs). The power connectors are typically designed to engage the circuit breaker clusters, field serviceable connections, and current and metering transformers.
Heretofore, various prior art approaches have been proposed for securing clusters to the pivots of circuit breakers. For example, one current approach requires fastening the clusters to the pivots using a U-shaped retainer pin and a retainer clip. Another current approach requires securing a cage around each group of clusters to anchor them onto the pivots. These approaches for securing clusters to circuit breaker pivots undesirably require additional installation time and labor due to the need for installing additional parts and for preforming additional installation steps. Many prior art approaches offer little by way of design to prevent misalignment of the electrically conductive fingers when securing a cluster to a pivot or when mating a cluster with a stab terminal. Likewise, many prior art designs do little to prevent the clusters from being displaced and/or becoming dislodged during handling and racking of the circuit breaker. What is needed are solutions that firmly and reliably secure the clusters onto their pivots with minimal complexity and fewer parts thereby reducing labor and material costs.
Disclosed herein are power connection systems that include self-aligning features and positive-latching connectors that help to obviate one or more of the aforementioned deficiencies in the prior art. For example, a variety of different configurations for self-locking self-aligning cluster connectors and positive-latching cluster supports are presented herein. In an exemplary configuration, each cluster connector includes opposing stacks of electrically conductive fingers that are shaped and sized to straddle a complementary pivot of an electrically conductive support. The finger stacks are pivotably mounted inside a cage with a respective leaf spring pressing against each stack of fingers. The leaf springs cooperatively bias together the proximal ends of the finger stacks to thereby hold the cluster on the pivot.
The proximal ends of the finger stacks cooperatively define a channel within which is received a complementary pivot of the cluster support. Projecting from the pivot is a contoured latch, such as a T-shaped rail, for latching the pivot to a cluster assembly. The contoured latch may take on other functional shapes that can provide the desired positive-latching function, such as T-shaped, mushroom-shaped, or triangular-shaped projections and rails. Once received inside a slot cooperatively defined by the proximal ends of the cluster fingers, the contoured latch of the pivot and the biased fingers of the cluster together lock the cluster connector to the cluster support. In addition, a forward-facing surface of the contoured latch is provided with angled guide surfaces which cooperate with complementary guide surfaces of the finger stacks to automatically align the fingers when the cluster is being secured to the pivot. The pivot and contoured latch can also be shaped and sized to allow the cluster to rotate on the pivot, allowing for the cluster to realign itself when being pressed onto the stabs of a bus bar connector. Some of the disclosed embodiments eliminate all space between the cluster fingers; this design allows for the stacking of cluster fingers one directly on top of the other which increases the cross section of conductive material which, in turn, increases the current carrying capacity of the cluster assembly.
Many of the disclosed power connection systems can be factory installed as well as retrofit into existing switchgear assemblies, and include parts that are easily replaceable in the field. When properly installed, these systems can significantly reduce the risk of cluster assemblies falling off during the handling, installation and removal of a circuit breaker assembly. In some of the disclosed embodiments, the power connection system's design is optimized to increase functionality while also reducing cost through reduced part complexity and reduced part count. In addition, the self-alignment feature allows for installation with live current-carrying members. In some embodiments, springs on each side of a cluster assembly allow each of the electrically conductive fingers to independently adjust to irregularities on contact surface points of the pivot. In addition, these designs are more efficient to manufacture and install by eliminating the need for specialized tools for installation. For some configurations, the cluster fingers can be hand squeezed for installation and removal of cluster assemblies.
According to one aspect of the present disclosure, a power connection system is presented for electrically connecting a circuit breaker to an electrically conductive bus bar. The power connection system includes an electrically conductive cluster support that is configured to attach to the circuit breaker. The cluster support has a base, a pivot projecting from the base, and a contoured latch projecting from the pivot. The power connection system also includes an electrically conductive cluster connector that is configured to electrically couple to the bus bar. The cluster connector includes a cage and opposing pairs of electrically conductive fingers that are pivotably attached to the cage. Each finger has opposing proximal and distal end portions. The proximal end portions of the opposing pairs of fingers are configured to straddle the pivot of the cluster support. The cluster connector also includes first and second spring members that bias the proximal end portions of the opposing pairs of fingers toward one another. The proximal end portions of the fingers cooperatively define a channel that is configured to receive the pivot. The proximal end portions further define a slot that is configured to receive the contoured latch of the pivot to thereby secure the cluster connector to the cluster support.
According to other aspects of the present disclosure, a switchgear assembly is presented for electrically coupling a circuit breaker to an electrically conductive power bus bar. The switch gear assembly includes a housing that is configured to receive therein the circuit breaker, and a backmold mounted at a distal end of the housing. The switch gear assembly also includes an electrical power connector with a stab terminal projecting from a base. The base of the power connector is mounted to the backmold and configured to electrically connect to the bus bar. Also included is an electrically conductive cluster support that is configured to attach to the circuit breaker. The cluster support has a base, a pivot projecting from the base, and a contoured latch projecting from the pivot. The switch gear assembly further comprises an electrically conductive cluster connector including a cage, a cluster, and first and second spring members. The cluster includes opposing pairs of electrically conductive fingers that are pivotably attached to the cage. Each finger has opposing proximal and distal end portions, where the proximal end portions of the fingers are configured to straddle the pivot of the cluster support, and the distal end portions are configured to electrically mate with the stab terminal of the electrical power connector. The spring members bias the proximal end portions of the opposing pairs of fingers toward one another. The proximal end portions of the cluster fingers cooperatively define a channel that is configured to receive the pivot, and further define a slot that is configured to receive the contoured latch of the pivot to thereby secure the cluster connector to the cluster support.
According to additional aspects of this disclosure, a self-locking cluster connector is disclosed for connecting a circuit breaker to an electrically conductive bus bar. The bus bar includes an electrical power connector with a stab terminal, and the circuit breaker includes a cluster support with a pivot projecting from a base. The cluster connector includes a cage with first and second opposing stacks of electrically conductive asymmetric plates disposed inside of and pivotably attached to the cage. Each plate has opposing first and second end portions, where the first end portions are configured to receive and attach to the cluster support of the circuit breaker, and the second end portions are configured to receive and electrically mate with the stab terminal of the bus bar. The cluster connector also includes first and second biasing members, each of which is engaged with a respective one of the stacks of plates. The first and second biasing members cooperatively bias the first end portions of the stacks of plates towards one another. The first end portions of the asymmetric plates cooperatively define a channel that is configured to seat therein the pivot of the cluster support. The first end portions further define a slot configured to trap therein a complementary contoured latch projecting from the pivot to thereby lock the cluster connector to the cluster support.
The foregoing summary is not intended to represent each embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel features and aspects included herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of exemplary embodiments and modes for carrying out the present invention when taken in connection with the accompanying drawings and appended claims.
While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
This invention is susceptible of embodiment in many different forms. There are shown in the drawings and will herein be described in detail representative embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiments illustrated. To that extent, elements and limitations that are disclosed, for example, in the Abstract, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise.
Referring now to the drawings, wherein like reference numbers refer to like components throughout the several views,
In the illustrated embodiment, the circuit breaker assembly 10 is electrically coupled to the switchgear assembly 12 via one or more electrically conductive power connectors 14, which can be of the turnable joint mount (TJM) connector type. Although only one electrical power connector 14 is shown in
It should be understood that the drawings are not necessarily to scale and are provided purely for explanatory purposes; as such, the individual and relative dimensions and orientations presented herein are not to be considered limiting. To that end, the circuit breaker 10 can include greater or fewer than three cluster supports 20A-C of similar or differing structure to that shown in the drawings. In a similar regard, each cluster support 20A-C can include greater or fewer than two cluster pivots 22A-F of similar or differing structure to that shown in the drawings. Likewise, each pivot 22A-F can be sized to support greater or fewer than three breaker connectors 30A-C (also referred to herein as “cluster connector”).
The power connector 14 comprises three primary segments: a fork-shaped head 24, a base 26, and a yoke 28. In general, the yoke 26 extends between and electrically connects the base 26 to the fork-shaped head 24. The head 24, base 26, and yoke 28 can be integrally formed as a single-piece, monolithic structure, as seen in
The circuit breaker 10 is electrically coupled to each power connector 14 by one or more columns 16A-F of self-locking “cluster-type” breaker connectors, three of which are designated 30A-C in
Although shown interfacing with six breaker clusters 30A-C, each power connector 14 can be configured to mate with fewer or greater than six cluster connectors 30A-C, each of which may be similar or different in design to the breaker clusters shown in the drawings. For example, the power connector 14 can be configured to mate with one or more of the cluster connector designs presented in commonly owned U.S. Pat. No. 8,197,289 B1, to Timothy R. Faber et al., which is incorporated herein by reference in its entirety and for all purposes. In the same vein, the cluster connectors disclosed herein can be adapted to incorporate many of the options, features and alternatives disclosed in the aforementioned '289 Patent. For some alternative embodiments, the cluster connectors 30A-C are locked to pivot(s) that are rigidly mounted to the backmold 11 of the switchgear assembly 12,
With reference next to
One or more pivots 22A-B project from the base 36 of each cluster support 20A. As indicated above, the cluster support 20A of
At least one and, in some embodiments, two or more contoured latches 40A-F project from the forward-most portion of each pivot 22A-B (i.e., the portion facing the backmold 11 and power connector 14). In accord with the illustrated example, each contoured latch 40A-F is an elongated T-shaped rail for latching one of the cluster assemblies 30A-C to the pivot 22A-B. According to the embodiment shown in
When properly seated on a corresponding cluster support 20A-C and mated with a corresponding power connector 14, the electrically conductive cluster connectors 30A-C operate as electrical conduits for passing electrical current between the circuit breaker 10 and the switchgear assembly 12.
In some embodiments, the plates 54 are substantially structurally identical; as such, the plates 54 will be collectively described herein with respect to a single plate 54′ shown on the far-left of
In addition, each of the middle portions 57 includes a first notch 58; when mated in opposing pairs, the notches 58 cooperatively define an elongated channel within which is received the spacer 50. The spacer 50, in turn, is attached to the cage 42 as described below to thereby pivotably mount the first and second opposing stacks of plates 52A and 52B to the cage 42. Each of the middle portions 57 also includes a second notch 59; when mated in opposing pairs, these notches 59 cooperatively define an elongated slot within which is received one of the contoured latches 40A-F.
As noted previously, the cluster connector 30A is designed to electrically connect an electrical switch, such as circuit breaker 10 of
With continuing reference to
The first and second leaf springs 46A, 46B (also referred to herein as “biasing members”) cooperatively bias the first end portions 53 of the pivotably mounted stacks of plates 52A, 52B laterally inwardly towards one another. By way of example, and not limitation, the first dual-fork-shaped leaf spring 46A is interleaved between the cage 42 and the first stack of fingers 52A, whereas the second dual-fork-shaped leaf spring 46B is interleaved between the cage 42 and the second stack of fingers 52B. A first (“lower”) end portion 65A of the first leaf spring 46A presses against the first end portions 53 of the first stack of fingers 52A, while a second (“upper”) end portion 67A of the first leaf spring 46A presses against the second end portions 55 of the first stack of fingers 52A. The first dual-fork-shaped leaf spring 46A is pinned within the cage 50, bowed inwardly by and pivoting about the inside edge of the first connecting arm 68. In a similar respect, a first (“lower”) end portion 65B of the second leaf spring 46B presses against the first end portions 53 of the second stack of fingers 52B, while a second (“upper”) end portion 67B of the second leaf spring 46B presses against the second end portions 55 of the second stack of fingers 52B. The second dual-fork-shaped leaf spring 46B is pinned within the cage 50, bowed inwardly by and pivoting about the inside edge of the second connecting arm 70. The connecting arms 68, 70 are longitudinally offset with respect to the centers of the leaf springs 46A, 46B and the pivot points (e.g., the spacer 50) of the opposing finger stacks 42A and 42B. Namely, the connecting arms 68, 70 are positioned closer to the first “lower” end portions 65A, 65B of the leaf springs 46A, 46B than the second “upper” end portions 67A, 67B of the leaf springs 46A, 46B. This acts to create a moment arm on the leaf springs 46A, 46B such that the leaf springs 46A, 46B bias the first end portions 53 of the fingers 54 inwardly (e.g., onto a cluster support 20).
The cluster connector 30A can be self-locking in that it can achieve and maintain a locked position on a pivot without the need for external features, such as retainer pins, retainer clips, anchors, special tools, etc. For example, the cluster connector 30A cooperates with the pivot 22A to provide “fastener grade” retention without using additional fasteners, clamps, or other separate attachment means, thus requiring fewer parts, reducing complexity, and reducing parts and labor costs. By way of example, and not limitation, the lower end portions 53 of the opposing pairs of fingers 54 are shaped to cooperatively define an elongated slot (generally designated by reference numeral 76 in
The power connection system of
As indicated above, the opposing stacks 52A-B of fingers 54 are pivotably attached to the cage 42 such that urging together the distal end portions 55 of the fingers 54 will pivot the first end portions 53 of the fingers 54 away from one another such that the cluster connector 30A can be seated on or removed from the pivot 22A of the cluster support 20A. For some optional configurations,
Turning next to
The cluster 44 generally includes first and second opposing stacks 152A and 152B, respectively, of electrically conductive, elongated, asymmetric plates or “fingers” 154. The plates 154 can be mated in opposing pairs and pivotably mounted to a cage, for example, via the spacer 150. Each plate 154 can be a single-piece, unitary structure that is fabricated (e.g., stamped) from an electrically conductive material, such as aluminum or copper. Unlike the cluster connector 30A described above, the fingers 154 of the cluster connector 130 include retention hooks 180 that provide additional contact surface area between the first end portions 153 of the fingers 154 and the pivot 122 of the cluster support 120. The retention hooks 180 also provide additional securing means for locking the cluster 144 to the pivot 122 and thereby preventing the unintentional dislodging of the cluster connector 130 from the cluster support 120.
While particular aspects, embodiments, and applications of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims. Lastly, all of the patent and non-patent literature discussed above is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US13/30160 | 3/11/2013 | WO | 00 |