Abstract:
A bus bar for electrical power distribution may be an elongated extruded metal bar having slots extending the entire length thereof. The slots may be of T-shape cross section, each with the channel opening through a face of the bar. Bolts are arranged with their heads captured in, and slidable along the length of the slots to any desired position. The bolts may have threaded stems which extend from the head through the channel of the T-slot in which its head is disposed and beyond that face of the bar through which the associated T-slot opens. Each stem is adapted to threadably receive a nut for clamping, supporting or connecting lugs to the bar. The bus bars can be mounted on insulating support members.

Description:
[0001]    This claims the benefit of U.S. Provisional Patent Application Ser. No. 62/275,285, filed Jan. 6, 2016 and hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to a bus bar for electrical power distribution. 
         [0003]    In the field of electrical power devices, a wide range of devices are known and currently available for distributing, converting, producing, and applying power. Depending upon the application, such devices may distribute incoming power to various devices and/or convert incoming power from one form to another as needed by a load. In a typical drive system arrangement, for example, constant (or varying) frequency alternating current power (such as from a utility grid or generator) is converted to controlled frequency alternating current power to drive motors, and other loads. In this type of application, the frequency of the output power can be regulated to control the speed of the motor or other device. Further, drive system buses may distribute the power throughout the process. In a motor control center application, a bus system may facilitate distribution of power to a number of system components and devices. For example, a motor control center bus may be utilized to provide power to a drive system bus. Further, such electrical installations may include bus work that communicatively couples the components with a power source and/or other components. 
         [0004]    Bus bars  1  for electrical distribution have been in the form of metallic straps which are first cut to length and then provided with sets of holes  3  through which bolts  5  are received for mounting the bus bars on suitable supports within a cabinet, for connecting them to each other, and for mounting electrical cable connectors  7  for conductors  9  thereon as shown generally in  FIGS. 1A and 1B . Usually the locations of the holes  3  are predetermined for specific arrangements, the holes being punched by the manufacturer at precise predetermined positions. 
         [0005]    Moreover, with the prior art bus bars and the associated supports, a technician needs to have access underneath the bus bar for a wrench or the like for securing the supports and bus bar to each other and the supporting surface. As a result, the height of the bus bar from the supporting surface is significant to provide for clearance and required access. 
         [0006]    The use of holes in specific positions along the bus bars limits the possible positions of the bus bars relative to each other and to supporting structure to specific arrangements of the original design. Consequently, for each different type and size of installation, holes have to be specially laid out and punched in the bus bars. Considerable layout time and expense is involved in positioning and punching the selected holes. This is both inefficient and labor intensive. 
         [0007]    Another undesirable feature of prior bus bar designs is that the current carrying capacity of the bars is not uniform for all cross sections throughout its length as the total cross section for conducting metal is reduced at those areas in which the holes are provided relative to those areas in which no hole is provided. Accordingly, assuming a bar of uniform thickness and overall width, to provide an amount of conducting cross section at the location of the holes sufficient to meet the rated maximum current carrying capacity of the bar results in an excess of conducting cross section at the imperforate portions, and a resultant waste or inefficient use of the metal. 
         [0008]    Traditionally, such bus work is manufactured to a specific length with punched holes or a combination of cabling and bus work to provide for electrical transmission to components. Such bus work may be directly affixed to an electrical enclosure by a fastener (e.g., a nut and bolt assembly) and a non-conductive standoff. Such bus work and attachment features can be complex, expensive, nonadjustable and/or difficult to configure. Many such bus bars must comply with standards for the hole spacing such as NEMA 1.7. Traditional bus work may be generally cumbersome and only enable coupling of attachment features at specific locations on the bus (e.g., punched holes along the bus). Additionally, traditional bus systems and support structures require substantial changes to accommodate different amperage levels or installation requirements. 
         [0009]    Accordingly, it is now recognized that it would be desirable to develop a bus system that facilitates electrical conductivity and the like in a flexible configuration, enables simplified manufacturing changes to accommodate different amperage levels and electrical enclosure arrangements, enables convenient coupling of attachment features at generally any location along the bus and delivers consistent capacity along the bus bar. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention in various embodiments is a copper or aluminum bar with one or more T or other shaped slots in the upper surface to which lugs are bolted to the bar via a compatible connector seated in the slot. In this way, the position of the connector on the bar is adjustable and the mounting capacity of the bar is maximized. An insulator or non-conductive support member is used to attach the bus bar. The attaching bolt for the insulator is recessed to allow attachment of electrical devices across the entirety of the bus bar surface. A slot may also be provided in the bottom surface of the bar for adjustable mounting of the isolator. 
         [0011]    The lugs may include a downwardly extending tab on the bottom of the lug which seats against the upper edge of the bar or in a groove on the top of the bar to prevent the lug from twisting or rotating relative to the bar. 
         [0012]    In accordance with various embodiments of this invention, the bus bar can be a length cut from a simple extrusion with certain slots therein extending the full length thereof, and so shaped and arranged that suitable attachment features or lugs can be positioned and secured firmly in place at any location desired along the length of the bar, and so that two lengths of the bar can be connected together readily in end to end relation with their faces coplanar or with their faces at an abrupt angle to each other. Traditional bus bars may be as much as twice as wide as bus bars according to this invention to accommodate similar connection schemes. Also, electrical connections can be made to the bar at any position desired along the length of the bar. Further, the lengths of bar may be attached readily to supporting structures at any and all locations along its length. This allows for unique and specialized configurations for mounting the bus bar assembly in electrical enclosures or other enclosures. The required NEMA spacing is readily accommodated with the bus bar system of this invention. The spacing between the lugs on this bus bar is dictated by the width of the lugs and not the standard NEMA spacing of 1.75 inches or the like. Moreover, the support members for the bus bar allow for less clearance than prior designs and the bus bars can be mounted end to end with no interference from mounting hardware. In addition to conductor attachment hardware such as lugs and the like, the tang of a fuse may be directly attached to the bus bar of this invention. 
         [0013]    Various other objects and advantages will become apparent from the following description wherein reference is made to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0015]      FIGS. 1A and 1B  are each perspective views of prior art bus bars for electrical distribution; 
           [0016]      FIGS. 2A and 2B  are each perspective views of slotted bus bars for electric distribution according to various embodiments of this invention; 
           [0017]      FIG. 3  is a perspective view of a further embodiment of a slotted bus bar for electric distribution according to this invention; 
           [0018]      FIG. 4  is a cross sectional view of a still further embodiment of a slotted bus bar for electric distribution according to this invention; 
           [0019]      FIG. 5  is a cross sectional view of a yet further embodiment of a slotted bus bar for electric distribution according to this invention; 
           [0020]      FIG. 5A  is a detailed view of region A from  FIG. 5 ; and 
           [0021]      FIG. 6  is a perspective view of another embodiment of a slotted bus bar for electric distribution according to this invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    As discussed in detail below, embodiments of this invention provide a bus system  10  that facilitates flexible configuration and connection of components to a bus bar  12 . In particular, this invention provides an extruded bus bar  12 , as well as attachment features  14  and support members  16  for the bus bar  12 . A support member  16  includes an insulated component that supports the bus bar  12  for attachment. 
         [0023]    References in the specification to “one embodiment,” “an embodiment,” or “an exemplary embodiment,” indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
         [0024]      FIG. 2A  illustrates a front perspective view of a universal bus bar assembly  10 . The universal bus bar assembly  10  includes a bus bar  12  and support members  16  directly attached at opposite ends and of the bus bar  12  attaching the universal bus bar system  10  to a mounting surface. The universal bus bar system  10  is configured to attach to various types or numbers of conductors  9  in an electrical system, to provide additional functionality to solve some of the issues experienced with prior bus bar assemblies. The universal bus bar system  10  may be used in industrial automation, building automation, control systems, power systems, telecommunications systems, or other applications where an electrical system is installed. 
         [0025]    The bus bar  12  may be extruded using a conductive material such as bare copper, tin-plated copper, aluminum, tin-plated aluminum, bronze, nickel, silver, gold plating or other types of conductive material. The extrusion process allows for easy size, shape, and configuration changes in the bus bar  12 . In other embodiments, the bus bar  12  may be manufactured using varying manufacturing processes or other types of materials. In other embodiments, the length of the bus bar may vary. 
         [0026]    During operation of the illustrated embodiments, the bus bar  12  receives power and distributes the power to various components via the conductors  9 . The bus bars  12  may function to provide three-phase AC power from an electrical grid from the utility company or other power generation source such as a generator, photo-voltaic or wind source to drive systems that function to reduce the three-phase AC power from the grid to a level that is desirable for a particular load, such as a motor. That is, the bus bars  12  function to distribute power to the systems at a voltage and frequency of the power source, distribute power within the systems as direct or alternating current, and distribute power out of the systems to the load at a desired voltage and frequency for the load. 
         [0027]    Each of the illustrated attachment features  14  receives a conductor  9  and is configured to couple with one of the slots  18  in the bus bar  12 . The attachment features  14  may take any of a variety of configurations such as the lugs shown in  FIGS. 2A and 6 . The slots  18  have a cross-section that includes a narrow channel  20  in communication with an expanded cavity  22 . Thus, the slots  18  can slideably receive a component of the attachment features  14  with a narrow neck  24  and an expanded distal end  26  such as a threaded bolt having a head and a shaft or other mechanical fastener. In other words, a component of an attachment feature  14  including a narrow neck  24  and an expanded distal end  26  can slide along one of the slots  18  when the narrow neck or shaft  24  is positioned within the narrow channel  20  and the expanded distal end or head  26  is positioned within the expanded cavity  22 . For example, in the illustrated embodiment of  FIG. 2A , the attachment feature  14  includes a pair of bolts that pass through a bracket or body  28  of the attachment feature  14  and into the slots  18 . The attachment features  14  and associated bolt head  26  may be inserted into the corresponding slots  18  at an end of the bus bars  14  or via openings that are manufactured into each of the slots  18 . By positioning the bolts  14  within the slots  18  in this manner, a nut  30  on the upper end of the bolt shaft  24  can be tightened such that the head  26  of the bolt  14  is pulled against an inner lip  32  of each slot  18 . Thus, the attachment feature  14  is securely fastened to the bus bar  12 . A washer  34  may be included on the attachment feature  14  as shown in  FIG. 2A . 
         [0028]    Multiple slots  18  are employed in the face of the bus bars  12  of  FIGS. 2A, 2B, 3, 5 and 6  to increase the quantity of the attachment features  14  on the bus bar  12  and to facilitate uniform contact between the bus bar  12  and the attachment features  14 . It should be noted that while two slots i 8  are provided in the bus bar embodiment illustrated by  FIGS. 2A-3, 5 and 6 , in other embodiments, only one slot or additional slots may be included. 
         [0029]      FIGS. 2A, 3 and 6  illustrate various embodiments of an isolative support member  16  attached to each end of the bus bar  12 . The isolative support member  16  may be made of a non-conductive material such as plastic in order to electrically insulate the bus bar  12  from the mounting surface to prevent the electrical charge running through the bus bar  12  from passing through the insulating support members  16  into the mounting surface. 
         [0030]    The support member  16  shown in  FIGS. 2A and 6  are secured to the bus bar via a bolt, screw or other fastener  36  inserted through a hole  38  proximate the end of the bus bar  12 . The fastener  36  extends though the hole  38  in the bus bar  12  and into the plastic or other electrically non-conductive material of the support member body  40 . 
         [0031]    An alternative attachment scheme for the support member  16  to the bus bar  12  is shown in the bus bar embodiment of  FIGS. 5 and 5A  in which a slot  42  is formed in the bottom surface of the bus bar  12 . The slot  42  of the embodiment of the bus bar  12  shown in  FIGS. 5 and 5A  is generally T-shaped similar to the slots  18  formed on the upper surface of the bus bar  12  for attachment of the lugs or attachment features  14  as previously discussed. With the slot  42  formed on the bottom surface of the bus bar  12 , the support member  16  is secured to the bus bar  12  via a bolt  36  with the head  44  of the bolt  36  seated in the expanded cavity  46  of the slot  42  and the shaft  48  of the bolt  36  extending from the head  44  through the narrow channel  50  of the slot  42  for attachment of the support member  16 . With the attachment arrangement for the support member  16  as shown in  FIGS. 5 and 5A , the support members  16  may be slidably positioned along the length of the bus bar  12  for proper positioning and support of the bus bar system  10 . Additionally, access to the head  44  of the fastener  36  is not required via the upper face of the bus bar  12  as with the attachment arrangement for the support member  16  shown in  FIGS. 2A and 6 . As such, the T-slot arrangement for attachment of the support member  16  on the bottom surface of the bus bar  12  provides access to the entire upper surface of the bus bar  12  for the attachment features and lugs  14  for optimum utilization of the bus bar  12 . Nevertheless, with the head  44  of the fastener countersunk so that it is flush with the upper surface of the bus bar  12  according to the arrangement shown in  FIGS. 2A and 6 , once the support members  16  are secured to the bus bar  12 , the attachment features or lugs  14  can be positioned anywhere along the upper surface of the bus bar  12 , including on top of the head  44  of the fastener likewise utilizing the entire surface of the bus bar  12  for attachment to the conductors  9  or other components. Naturally, as one of ordinary skill in the art will appreciate, the shape of any of the slots  18 ,  42  shown or described herein may be varied while still remaining within the scope of this invention. 
         [0032]    The support members  16  according to another embodiment of this invention are shown in  FIG. 3  and include spaced, generally molded support members  16  which are coupled to the bus bar  12  at the end of the bus bar  12 . These support members  16  avoid the need for drilling any holes in the bus bar  12 . Support members  16  do not require a hole, slot for other formation in the bus bar  12  for attachment. The support members  16  include laterally extending feet  16   a  which may include holes  16   b  for mounting the bus bar assembly  10  to a support surface. The support members  16  of  FIG. 3  may include tabs or other features which are seated within the various grooves, slots or features of the bus bar  12  for secure attachment and coupling of the bus bar to the support member  16 . The support member  16  of the embodiment of  FIG. 3  is likewise made from a plastic, rubber or other non-conductive insulating material. 
         [0033]    Another feature of various embodiments of this invention is shown in the bus bars  12  of  FIGS. 2A-6  and includes a downwardly projecting tab  52  on a bottom surface of the attachment feature or lug  14 . As most clearly shown in  FIG. 6 , the tab  52  projects downwardly from the bottom surface of the lug  14  and engages an edge  54  of the bus bar  12 . The interaction between the tab  52  and the bus bar  12  inhibits or prevents rotation of the attachment feature  14  relative to the bus bar  12 . In this manner, during tightening of the bolt which secures the attachment feature  14  to the bus bar  12 , the lug  14  does not rotate or spin because such movement is prevented by the tab  52  seated against the edge  54  of the bus bar  12 . In the embodiments of the bus bar  12  shown in  FIGS. 2A-5 , the tab  52  may be seated within a groove  56  formed in the upper surface of the bus bar  12 . The groove  56  may extend the entire length of the bus bar  12  thereby allowing for positioning of the attachment features  14  anywhere along the length of the bus bar  12  with the respective tab  52  seated within the groove  56  to inhibit rotation of the attachment feature  14  relative to the bus bar  12 . The embodiment of this invention shown in  FIG. 6  utilizes the outer side edge  54  of the bus bar  12  for engagement with the tab  52  to prevent relative rotational movement while the groove  56  is provided in other embodiments. These and other features comprise an anti-rotation feature of the bus bar system according to various embodiments of this invention. 
         [0034]    Another feature of various embodiments of the bus bar  12  according to this invention is clearly shown in the embodiment of  FIGS. 2A-5  in which an undercut feature or chamfer  58  is formed in the outer side edges of the bus bar  12 . One purpose of this feature is to reduce or minimize the weight and quantity of material required for forming the bus bar  12 . Naturally, this feature or chamfer  58  may take a variety of shapes, configurations or sizes and be positioned as shown in the drawings or at other locations on the bus bar  12  as appropriate. 
         [0035]    A bus bar  12  of this invention has distinct advantages structurally and for convenience in manufacture and in assemblage. In the first place, the bar  12  can be extruded in a continuous piece of the stock length desired, and cut into the lengths required for the particular installation. Further, the current carrying capacity of the bar  12 , at each cross section along its length, is equal to the current carrying capacity at every other cross section, as the cross section is uniform in size and shape throughout the entire length of the bar  12 . Further, attachment features  14  for making electrical connections can be disposed in any position desired along the slots  16  and there secured to the bus bar  12 . The bar  12  can be extruded with T-shaped longitudinal slots  16 ,  42  and grooves  56  on the faces of the side walls. 
         [0036]    From the above disclosure of the general principles of this invention and the preceding detailed description of at least one embodiment, those skilled in the art will readily comprehend the various modifications to which this invention is susceptible. Therefore, we desire to be limited only by the scope of the following claims and equivalents thereof.