Abstract:
A bus duct system comprising straight sections of bus duct, bracing members in said bus duct to support a plurality of flat bus bars in spaced apart relationship, access opening for tap-off boxes having sliding doors to open and close said access openings. The bus duct sections include slots in the walls of the bus duct to receive projections of the bracing members to hold the bracing members in position within the bus duct. The bracing members are located adjacent the access openings to provide stability for connecting a tap-off box to the bus bars.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a bus duct system in which bus bars for carrying electric current are mounted and enclosed within sections of bus duct housing. Such bus duct systems include means for connecting tap-off units to the bus bars. Existing systems have relatively complex and expensive structures for providing tap-off connections, including supporting, bracing and mounting means at and adjacent to the sections of the bus duct in which the tap-off connection is made. In accordance with the present invention, simplified bracing members are provided as well as simplified means for securing bracing members to the bus duct. The bracing members are also located in a position to lend support to the bus bars when tap-off units are being connected thereto. The access openings are provided with simplified sliding doors, for which mounting means and track means are formed as integral parts of the bus duct walls and the cooperatively mounted bracing members. 
     It is an object of the present invention to provide a bus duct system which combines a bracing molding and a sliding shutter to allow, at low cost, access to the bus bars for attachment, for example, of a tap-off box. 
     It is a further object of the present invention to provide a bus duct system which minimizes the number of different joints required and which simplifies the construction of the joints. 
     According to one aspect of the present invention there is provided a bus duct system comprising an elongate section forming a housing having flat bus bars therein, means for supporting and bracing the bus bars in the housing at a number of spaced apart positions in the section and at least one sliding shutter located adjacent at least one of said means to allow access to the bus bars. 
     According to a second aspect of the present invention there is provided a bus duct system comprising a plurality of elongate sections forming a housing for bus bars, a number of different joints joining said sections together, the joints being formed from a number of component parts wherein at least some of said component parts are common to a number of different joints. 
     Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a bus duct system embodying both aspects of the present invention; 
     FIG. 2 is an elevational view of a section of the bus duct system of FIG. 1; 
     FIG. 3 is a sectional elevational view of a bracing member; 
     FIG. 4 is a plan view of the member of FIG. 3; 
     FIG. 5 is a perspective view of part of the duct section of FIG. 2 showing the location of the bracing member and the position of the sliding door; 
     FIG. 6 is an elevational sectional view through the bus section of FIG. 5 and showing a fused tap-off box fitted to the bus bar; 
     FIGS. 7 and 8 are an elevational sectional view and an end view respectively of a contact assembly mounted in a straight joint; 
     FIGS. 9 and 10 are a top plan view and a perspective view respectively of a straight joint; 
     FIGS. 11 and 12 are a top plan view and a perspective view respectively of an edgewise elbow joint; 
     FIGS. 13 and 14 are a top plan view and a perspective view respectively of an edgewise tee joint; 
     FIGS. 15 and 16 are a top plan view and a perspective view respectively of an edgewise cross joint; 
     FIGS. 17 and 18 are an elevational view and a perspective view respectively of a flat elbow joint; and 
     FIG. 19 is a perspective view of an end cap. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 of the drawings, there is shown a perspective view of a bus duct system in accordance with the present invention. 
     The system comprises a number of longitudinal sections 1 which form a housing for longitudinally extending bus bars, normally four. The sections 1 are joined by a number of different joints which will hereinafter be termed as follows: 
     a straight joint 10; an edgewise elbow joint 20; an edgewise tee joint 30; an edgewise cross joint 40; and a flat elbow joint 50. 
     The end of one section 1a is closed by an endcap 60. A number of tap-off boxes 100 may be fixed at different positions along the sections 1 in a manner to be described. 
     Referring now to FIG. 2, each of the longitudinal sections 1 is provided, on both of its lateral sides, with a number of spaced apart openings or passages 2. On both lateral sides and at each of the ends of the sections 1, an indentation 3 is provided offset from the central axis of the section 1 to locate one of a number of the above mentioned joints. A number of pairs of locating slots 4 are provided in each of the sections, each pair being longitudinally spaced from the adjacent pair and serving to locate a bracing member 5 (FIG. 3). Alternate pairs of slots 4 are located adjacent the openings 2. 
     FIG. 3 shows the bracing member 5 in the form of a molding and having projections 5a to engage the slots 4 in the duct sections 1. The bracing member 5 has four openings 5b to receive and support four bus bars 7, as can be seen in FIG. 5. 
     FIG. 5 also shows the operation of a sliding shutter 6 for closing the aperture or passage 2 in an assembled duct section. The sliding door 6 slides across the opening 2 in the duct section 1 when access is not required to the bus bars 7. The shutter 6 is constrained along its top and bottom edges by a top surface and bottom surface of portions of member 5 engaging a side wall to define a guideway formed from recesses 5c on the bracing member 5 to slide along the inner face of the side of the duct section 1 and the extent of its travel is limited by a screw 6a which engages respective notches 2a and 2b of the opening 2. 
     FIG. 6 shows a fused tap-off box 100 mounted on the duct section 1. The tap-off box 100 is provided with four double ended jaw assemblies 101 which pass through the openings 2 and engage respective bus bars 7, the tap-off box 100 being thereafter fixed to the duct section 1 by clamps 102. 
     Since a bracing member 5 is located adjacent each opening 2, access is provided to the bus bars 7 adjacent the point of support of the bus bars in the duct section 1, and the bracing member directly supports the bus bars against external forces which occur on insertion of the jaws of the tap-off box 100. 
     Each of the different joints for joining sections of the bus duct will now be described. 
     The ends of bus bars 7 of one section are joined to the ends of respective bus bars of an adjacent section by means of a joint which includes at least one contact assembly 8. 
     FIGS. 7 and 8 show such a contact assembly located in a straight joint 10. Each contact assembly 8 is made up of four pairs of joint contacts 81, each pair being separated by one of three insulators 82. The outermost contacts are provided with a pair of outer insulators 83. The assembly 8 is fixed together by means of a bolt 84 passing through an insulating tube 85 and engaging a nut 86. 
     FIGS. 9 and 10 show a straight joint 10 which includes one contact assembly 8, encased in a pair of side plates 11 and top and bottom plates 12. As can be seen in FIG. 10, the side plates 11 are provided with indented portions 13 which engage the indentations 3 formed in the side members of the duct sections 1. The straight joint is so assembled that each of the indented portions 13 is located above the central axis, and, since the indentations 3 are similarly positioned in the duct section 1, the straight joint is accurately located by the cooperation of the portions 13 and the indentations 3. 
     FIGS. 11 and 12 show an edgewise elbow joint 20. The edgewise elbow joint 20 includes two contact assemblies 8 arranged at right angles to each other and connected by four conducting elbow connectors 21. The housing for the edgewise elbow joint 20 is made up of top and bottom angle plates 22, two pairs of top and bottom plates or walls 23, an inside angle plate or wall 24 and an outside angle plate or wall 25. The top plate is provided with a raised portion 28 to receive the nut 86 of the contact assembly 8 and the bottom plate is provided with an aperture through which passes the head fo the bolt 84 of the contact assembly 8. 
     The inside angle plate 24 and outside angle plate 25 are provided with offset indented portions 26 and 27 respectively. These portions 26 and 27 engage the indentations 3 in respective duct sections 1. The orientation of the plates 24 and 25 is such that indented portions 26 and 27 are both located on the upper side of the central axis of the joint. 
     Both a righthand edgewise turn and a lefthand edgewise turn can be made using the same edgewise elbow joint. 
     FIGS. 13 and 14 show an edgewise tee joint 30. The edgewise tee joint includes three contact assemblies 8 connected by four conducting tee connectors 31. The housing of the edgewise tee joint 30 includes top and bottom center tee plates 32 three pairs of top and bottom plates 23, two inside angle plates 24 and a rear plate 38. The rear plate 38 is provided with indented portions 33 in a manner similar to the inside angle plates 24 and which also serve to engage the indentations 3 on the duct sections 1. The inside angle plates 24 and the top and bottom plates 23 are the same as the corresponding plates of the edgewise elbow joint. 
     FIGS. 15 and 16 show an edgewise cross joint 40. The edgewise cross joint 40 includes four contact assemblies 8 connected by four conducting cross connectors 41. The housing for the edgewise cross joint 40 includes top and bottom center cross plates 42, four pairs of top and bottom plates 23 and four inside angle plates 24. 
     The inside angle plates 24 and top and bottom plates 23 are the same and the corresponding plates of the edgewise elbow joint and edgewise tee joint. 
     Thus, the edgewise elbow joint 20, the edgewise tee joint 30 and the edgewise cross joint 40 employ in their construction, the top and bottom plates 23 and the inside angle plates 24. 
     FIGS. 17 and 18 show a flat elbow joint 50. The flat elbow joint 50 includes two contact assemblies 8 connected by four &#34;L&#34; shaped elbow conducting connectors 51a, 51b, 51c, and 51d, respectively. The housing for the flat elbow joint 50 includes a pair of side elbow plates 52, an inside angle member 53, an outside angle plate 54, two pairs of side plates 55 and a pair of inside plates 23. The side plates 55 are provided with offset indented portions 56 which engage the indentations 3 in the duct sections 1. 
     The orientation of the plates 55 determines whether an upward or a downward flat elbow joint is obtained and upward or downward joints can be formed using the same components. Additionally, the inside plates 23 of the flatwise elbow joint 50 are the same as the top and bottom plates used in the edgewise joints 20, 30 and 40. 
     FIG. 19 shows an endcap 60 formed of top and bottom plates 61 and an endplate 62. The endcap 60 serves to close a non-connected end of a bus duct section.