Patent Publication Number: US-7909663-B1

Title: Modular optimized plug-in jaw

Description:
FIELD OF THE INVENTION 
     This invention is directed generally to a electrical systems, and, more particularly, to a modular connector jaw for plug-in unit used in a busway system. 
     BACKGROUND OF THE INVENTION 
     Busway electrical distribution systems are well known in the art of electrical distribution. Busway systems are comprised of a number of factory assembled sections each including a number of individually insulated generally flat electrical conductors or busbars stacked one upon another and enclosed within a housing which provides protection and support for the busbars. For example, typical busway systems have 10-foot sections of flat, stacked, electrical conductors for transporting electrical energy from a point A to a point B, while distributing the electrical energy to various electrical loads. Busway construction is modular and, in many ways, is superior to cable and conduit systems from an installation standpoint. 
     For distribution of the electrical energy, the busway sections include one or more plug-in outlets having a plurality of conductive stabs. In general, the plug-in outlets include openings that are provided through the housing of the busway system at each of a plurality of power tap-off sections to expose conductive material of the busbars for connection with an appropriate connecting jaw. A plug-in unit, which is used to tap off power from the busway, is attached to a base in the plug-in opening by mounting a plurality of jaws to a corresponding stab, which extends from a respective busbar. 
     Present busway systems, however, fail to provide an efficient, cost-effective, and simple solution for installing plug-in units having different electrical load requirements (i.e., different ampacities). To install plug-in units of different ampacities, present busway systems must use different jaws, based on the respective load requirement. For example, the same jaw may be used for a load requirement of 30 Amperes, 60 Amperes, and 100 Amperes, but a different jaw must be used for a load requirement of 250 Amperes and 400 Amperes. Thus, one problem associated with the need for different jaws is that it increases manufacturing costs, wherein different jaws require different manufacturing tooling. Another problem associated with present jaws is that they typically provide a single line of contact per each side of the corresponding stab, wherein the line of contact may result in a single contact point based on alignment problems. These problems may be present in various electrical products, such as switchboards, panelboards, loadcenters, switchgears, circuit breakers, and others. 
     What is needed, therefore, is a jaw module for a plug-in unit of a busway system that addresses the above-stated and other problems. 
     SUMMARY OF THE INVENTION 
     In an implementation of the present invention, a modular jaw unit for a busway system includes a spring support member having a central section. The central section has a plurality of coupling bosses and a plurality of coupling slots. The coupling bosses are positioned on one side of the support member for inserting into respective coupling slots of another modular jaw unit. The coupling slots are positioned on an opposite side of the support member for receiving respective coupling bosses of the another modular jaw unit. Four independently moving support ends include two support ends extending from the central section in one direction and two support ends extending from the central section in an opposite direction. A pair of wires include a first wire and a second wire positioned within the support member. Each of the wires has two oppositely located wire ends such that each of the wire ends is adjacent to a respective one of the support ends of the support member. 
     In an alternative implementation of the present invention, a busway system includes a busbar assembly having a plurality of busbars for transporting and distributing electrical current to an electrical device. The busbar assembly has at least one plug-in opening through which at least one stab extends from one of the busbars. A plug-in unit provides a housing for the electrical device, e.g., a circuit breaker, and is mounted to the plug-in opening. A modular jaw is coupled to the plug-in unit for connecting a connector of the electrical device to the stab. The modular jaw has at least one modular unit that is capable of connecting to another modular unit such that the size of the modular jaw is changeable to accommodate different ampacity requirements. 
     In another alternative implementation of the present invention, a busway system includes a busbar assembly for distributing electrical current to an electrical device. The busbar assembly includes a busbar housing having at least one plug-in opening; a plurality of stacked busbars enclosed at least in part in the busbar housing; and at least one electrically conductive stab extending from a corresponding busbar through the plug-in opening. A plug-in unit is mounted to the plug-in opening, the plug-in unit enclosing at least in part the electrical device and the electrical device having an electrical connector for receiving electrical current. The busway system includes at least one electrically conducting modular jaw capable of having a plurality of modular units removably connected and identical to each other, the modular jaw having a first jaw end connected to the stab and a second jaw end connected to the electrical connector. Each of the modular units includes a spring support member having four independently moving support ends, two of the support ends being located at the first jaw end and two of the support ends being located at the second jaw end. The modular units further include a pair of wires that are placed at least in part within the spring support member, each of the wires having two oppositely located wire sections. The symmetry of the wires eliminates cost and enhances ease of assembly by eliminating, for example, the need for manufacturing and assembling two differently shaped wires. The modular units further include a closing member for securing the wires in the support member. At the first jaw end, the corresponding support ends force respective ones of the wire sections in contact with the stab, while at the second jaw end the corresponding support ends force respective ones of the wire sections in contact with the connector. 
     Additional aspects of the invention will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments, which is made with reference to the drawings, a brief description of which is provided below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings. 
         FIG. 1  is a perspective view of a busway system having a busbar assembly and plug-in unit with modular jaws. 
         FIG. 2A  is an exploded perspective view of a single modular jaw unit. 
         FIG. 2B  is an assembled top view of the jaw unit of  FIG. 2A . 
         FIG. 2C  is an assembled bottom view of the jaw unit of  FIG. 2A . 
         FIG. 2D  is an assembled side view of the jaw unit of  FIG. 2A . 
         FIG. 3A  is a perspective view illustrating modular stacking of a single modular jaw unit to a three-jaw modular unit. 
         FIG. 3B  is an enlarged view illustrating a snap connection between two adjacent jaw units. 
         FIG. 4A  is a top view illustrating mounting of different jaw units to corresponding stabs of a busway system. 
         FIG. 4B  is a side view of  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Although the invention will be described in connection with certain preferred embodiments, it will be understood that the invention is not limited to those particular embodiments. On the contrary, the invention is intended to include all alternatives, modifications and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims. 
     Referring to  FIG. 1 , a busway system  100  has a plug-in unit  102  that is mounted to a section of a busbar assembly  104 . The plug-in unit  102  typically houses a circuit breaker or fusible disconnect means. Other electrical devices that can be housed in the plug-in unit  102  for connecting to the busbar assembly  104  include, for example, switchboards, solar panels, safety switches, panelboards, loadcenters, and switchgears. The connection of the plug-in unit  102  to the busbar assembly  104  is made by electrical jaws  106  engaging corresponding stabs  108  of the busbar assembly  104 , which extend through a plug-in opening  110  of the busbar assembly  104 . On one end, the electrical jaws  106  engage the corresponding stabs  108 , and on another end, the electrical jaws  106  engage a corresponding connector of the electrical device being connected (e.g., an electrical connector of a circuit breaker). Each of the electrical jaws  106  can have one or more modular jaw units. 
     Referring to  FIGS. 2A-2D , a single modular jaw unit  200  has two copper wires  202  that are housed and supported by a stainless steel spring member  204 . The wires  202  have a wire section  214  that is located at each wire end and that is shaped to capture or connect an electrical connector. According to one example, the wires  202  have a diameter of approximately 0.080 inches. However, the diameter of the wires  202  can be larger or smaller based on optimization variables, such as performance, heat rise, etc. 
     A closing member in the form of a closing plate  206  locks the wires  202  in place to form a single jaw unit  200 . According to the illustrated embodiment, the closing plate  206  is connected to the spring member  204  by snapping the two together, wherein slots  208  of the closing plate  206  are snapped in place, respectively, over shoulders  210  of the spring member  204 . Alternatively, the spring member  204  is formed and folded over on itself to serve the same closing function as the closing plate  206 . In other words, instead of using the closing plate  206  as a separate member, the closing member is generally similar to the closing plate  206  but is formed integrally with the spring member  204  to lock the wires  202  in place for forming a single jaw unit  200 . In other embodiments, any components of the jaw unit  200  can be connected together by any other connecting methods, such as by using bolts, rivets, adhesives, screws, etc. 
     When assembled, the wires  202  are fixed in position by a pair of locating bosses  212 , which are positioned generally symmetrical to each other. Each wire section  214  of the wires  202  is in contact with a corresponding support end  216  of the spring member  204 . The support ends  216  extend from a central section  217  of the spring member  204 . 
     The support ends  216  are independently movable and are formed to have an inward rounded shape such that, upon contact with the wire sections  214 , they force the respective wire section  214  in contact with an electrical connector of the plug-in unit  102  or the stab  108 . As such, the jaw unit  200  is spring loaded on both ends, to provide good contact points and help minimize contact resistance in the current path at each contact point. 
     The jaw unit  200  provides a total of 4 electrical contact points A-D for each single jaw unit  200 . Two contact points, such as contact points A and B, are provided at one coupling end of the jaw unit  200  for connection with the stab  108 , and two contact points, such as contact points C and D, are provided at another coupling end of the jaw unit  200  for connection to an electrical module coupled to the plug-in unit  102  (e.g., a circuit breaker). The jaw unit  200  is removably connectable to the stab  108  and to the electrical module. Based on the removable connection (e.g., in contrast to a permanent connection in which a connecting jaw is integrated with a plug-in unit), an advantage of the jaw unit  200  is that a user can disconnect electrical components upstream of the jaw unit  200  to isolate electrical components downstream of the jaw unit  200  (such as for safe maintenance operations), without having to unplug the plug-in unit from the busbar assembly  104 . 
     The spring member  204  further has a plurality of coupling bosses  218  extending from an end point of a corresponding shoulder  210 . The coupling bosses  218  are provided for mounting the jaw unit  200  to another jaw unit  200 . Opposite to the coupling bosses  218 , the spring member  204  has a plurality of coupling slots  220  for receiving corresponding coupling bosses  218  of another jaw unit  200 . The mounting of the jaw unit  200  in a multi-unit jaw is described in more detail below. 
     The jaw unit  200  can be manufactured and assembled entirely using an automated assembly process. For example, an exemplary fully automated machine is a Bihler machine for stamping and bending sheet metal into the described components of the multi-jaw unit. The Bihler machine is manufactured by Otto Bihler Maschinenfabrik and is optionally available with an integrated PLM Software package from Siemens. The Bihler machine can stamp, bend, and cap sheet metal to form the jaw unit  200 , and, can assemble multiple jaw units  200  into a single multi-unit jaw. The fully automated manufacturing and assembly process is advantageous because it reduces cost, while producing a high volume of units. 
     Referring to  FIGS. 3A and 3B , a multi-unit jaw  300  includes four single jaw units  200   a - 200   d , with a fourth jaw unit  200   d  being illustrated in the process of being mounted. The single jaw units  200   a - 200   d  are mounted to each other by snapping coupling bosses  218  into corresponding coupling slots  220 . 
     For example, the coupling bosses  218   b  of a second jaw unit  200   b  are inserted (e.g., by snapping) into the coupling slots  220   a  of a first jaw unit  200   a ; the coupling bosses  218   c  of a third jaw unit  200   c  are inserted into the coupling slots  220   b  of the second jaw unit  200   b ; and the coupling bosses  218   d  of the fourth jaw unit  200   d  are inserted into the coupling slots  220   c  of the third jaw unit  200   c . The coupling bosses  218   a  of the first jaw unit  200   a  remain free at one end of the multi-unit jaw  300 , and the coupling slots  220   d  of the fourth jaw unit  200   d  remain open at the other end of the multi-unit jaw  300 . 
     According to other embodiments, other methods of connecting single jaw units into a multi-unit jaw can be used. For example, instead of a snapping method, the single jaw units can be connected to each other by riveting or bolting methods. In another example, a plug-in unit may also be equipped to accommodate support/shrouding features to facilitate the efficacious use of jaw units. 
     Referring to  FIGS. 4A and 4B , the multi-unit jaw  300  is illustrated connected to the corresponding stab  108 . The multi-unit jaw  300  provides a total of 8 contact points A 1 -A 4  and B 1 -B 4  with the stab  108 . Specifically, 4 contact points A 1 -A 4  are provided on one side of the multi-unit jaw  300 , and are formed by contact between the four wires  202   a - 202   d  of the single jaw units  200   a - 200   d  and the stab  108 . The remaining 4 contact points B 1 -B 4  are similarly provided and formed on an opposing side of the multi-unit jaw  300 . 
     The number of units of the multi-unit jaw  300  can vary based on electrical requirements. For example, a single multi-unit jaw  300  can be effectively used for an electrical load range from 30 Amperes to 800 Amperes, wherein the ampacity requirements are met by adding (or removing, as necessary) units from the multi-unit jaw  300 . 
     In accordance with this embodiment, the 8 contact points A 1 -A 4  and B 1 -B 4  are advantageous over current jaw connections in which only two contact points may be provided based on misalignment of the jaw with respect to the stab. The advantages of having an increased number of points includes improving the current path from the jaw to the bus bar, therefore reducing the electrical resistance at the interface. In turn, the improved current path improves local thermal performance. 
     While particular embodiments, aspects, and applications of the present invention have been illustrated and described, it is to be understood that the invention 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.