Abstract:
A drawout unit is dimensioned to make more efficient use of the space within the drawout unit. Devices within the drawout unit are positioned in a generally vertical configuration. A bus brace serves as a line/load terminal assembly. The bus brace has receptacle ports enabling lugs to maintain electrical contact with vertically oriented bus bars on the line terminals and transfer current to horizontally oriented load terminals. Output cables extend horizontally from the load terminals and form a single right angle bend before passing out of the bottom of the drawout unit through an exit port.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of application Ser. No. 09/438,108 Filed Nov. 10, 1999 now abandoned, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a drawout unit, and, more particularly, to a load/line terminal unit configured to make more efficient use of the space within the drawout unit. 
     In a motor control system, vertical bus bars which carry current to motor controller units are arranged vertically in drawout units. Sliding stabs usually plug into a housing with opposing prongs being biased toward each other on the sliding stabs to contact either side of the bus bars, whereby the electrical connection between the motor controller unit and the bus bars is maintained. Lugs on the sliding stabs are connected to bus straps extending from the lugs to the line side of a circuit interrupting device such as a circuit breaker. Bus straps also extend from the load side of the circuit interrupting device to the line side of a distribution power load circuit, such as a starter. 
     Load terminals are electrically connected to the load side of the distribution power load circuit and are typically positioned to allow an output cable to be connected to them in a vertical configuration. These load terminals are generally bushings positioned on the bottom of the distribution power load circuit and have an axially threaded terminal to which output cable connections are made. Alternately, output cables of a thinner diameter may have attachments on one end that allow them to be secured to load terminals with screws or bolts. One particular method of securing output cable to a load terminal, as described in U.S. Pat. No. 4,154,993 entitled “Cable Connected Drawout Switchgear”, involves mounting circuit equipment on a rolling carriage such that the load terminals engage connectors on stationary cables when the carriage is rolled over the cable connectors. Another method described in U.S. Pat. No. 5,107,396 entitled “Circuit Breaker Combined Terminal Lug and Connector” involves sliding a cable connector disposed axially on the end of a cable into a receiving slot on a terminal lug. Both of these methods of attaching output cable are such that the output cable depends vertically, and not horizontally, from the load terminals. 
     Output cable extending vertically down from the load terminals must be bent at two right angles thus forming an S-shape before passing through an exit port in the bottom of the drawout unit. Depending on the voltage class, output cable may be up to a few inches in diameter and relatively inflexible due to its construction. Consequently, the minimum bending radius of the cable may be large. Because of this large minimum bending radius of the cable, and because the output port through which the output cable passes is usually not directly below the load terminals, the cable must be bent at right angles twice to pass out of the drawout assembly. Bending the cable to form two right angles requires an appreciable amount of space more than a single right angle bend would require. Thus, the drawout assembly must be of a larger size than is really necessary to accommodate both right angle bends. Furthermore, as the number of output cables depending from the load terminals increases, an increasing amount of space is required at the bottom of the drawout to accommodate the cables. 
     SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, a drawout assembly is configured to confine an electrical motor control unit comprising a plurality of vertically arranged electrical devices. A load terminal is positioned on a bus brace having horizontally-oriented receptacles for receiving lugs which receive output cables. The horizontally-oriented receptacles allow the output cable to be bent only once at a right angle before passing vertically out of the bottom of the drawout assembly. The bus brace has disposed on it a plurality of these receptacles for receiving the lugs, which may or may not be aligned. The lugs are electrically secured within the receptacles to maintain electrical contact with line-connected bus straps positioned under the receptacles. 
     Attaching output cables to the load terminals in a horizontal configuration will enable the cables to be bent only once before they pass through the exit port. Use of only a single bend will thus allow the same stabs, bus straps, circuit interrupting device, distribution power load circuit, load terminals, and cable to be fit into a smaller drawout due to more efficient use of space. Use of a smaller drawout, while maintaining the same internal components, translates into a more manageable drawout 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a drawout of prior art construction illustrating a distance between the load terminal and the output cable port; 
     FIG. 2 is a schematic view of a drawout illustrating a decreased distance between the load terminal and the output cable port, of the present invention; 
     FIG. 3 is a schematic view of a drawout having a vertical stab housing, a circuit interrupting device, a distribution power load circuit, and a load terminal, of the present invention; 
     FIG. 4 is an elevated and exploded view of the drawout shown in FIG. 3; 
     FIG. 5 is an elevated and exploded view of the load terminal assembly, of the present invention; and 
     FIG. 6 is an elevated view of the bus brace of the load terminal assembly, of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a drawout box of the prior art is generally shown at  10 . Drawout box  10  is comprised of rigid panels to form a shell  12  that is open on one side. Shell  12  is movably connected to the inside of a second shell or bucket  13 . Situated within shell  12  is a distribution power load circuit  14  having a load terminal assembly  16  located generally on the bottom of distribution power load circuit  14 . A cable  18  extends vertically down from load terminal assembly  16  and twice is bent at right angles  20  before passing vertically down through an outlet port  22  in the bottom of bucket  13 . The radius of cable  18  in combination with right angles  20  defines a distance  24  between load terminal assembly  16  and the bottom wall of shell  12 . 
     FIG. 2 is a drawout box of an exemplary embodiment of the present invention generally shown at  30 . Drawout box  30  is comprised of rigid panels to form a shell  32  that is open on one side. Shell  32  is movably connected to the inside of a second shell or bucket  33 . A load terminal assembly  36  is located on the bottom of distribution power load circuit  34 . A cable  38  extends horizontally from load terminal assembly  36  and is bent only once at a right angle  40  before passing vertically down through an outlet port  42  in the bottom of bucket  33 . The radius of cable  38  in combination with single right angle  40  defines a distance  44  between load terminal assembly  36  and the bottom wall of shell  32 . Because of single right angle bend  40  in cable  38 , as opposed to double right angle bends  20  in cable  18 , distance  44  is less than distance  24 . Decreased distance  44  allows drawout box  30  to be made of smaller dimensions thus making a more efficient use of space within drawout box  30  and rendering drawout box  30  more manageable. 
     Referring to FIGS. 3 and 4, drawout box  30  is shown in greater detail. A drawout stab unit  50  receives power from bus bars (not shown). The construction of drawout stab unit  50  is well known in the art. Bus straps (not shown) connect drawout stab unit  50  to a line side  51  of a circuit interrupting device  52 . A load side  53  of circuit interrupting device  52  is connected by second set of bus straps  54  to a line side  55  of distribution power load circuit  34 . A third set of bus straps  70  connects a load side  56  of distribution power load circuit  34  to load terminal assembly  36 . 
     Load terminal assembly  36  is illustrated in FIG.  5 . Load terminal assembly  36  is comprised of a bus brace  60 , bus attachments  70 , and lugs  74 . Bus brace  60  is comprised of a base plate  61  and a plurality of lug-engaging receptacles  64 . Base plate  61  has an upper surface  62  and a lower surface  63 . Receptacles  64  are positioned on upper surface  62  of base plate  61 . Each receptacle  64  has three walls  65  positioned to be substantially perpendicular to base plate  61 . The bottoms of walls  65  are fixedly attached to upper surface  62  of base plate  61 .The base plate  61  includes holes  68  for securing the base plate  61  inside the drawout switchgear assembly. Openings  67  shown in phantom extend completely through base plate  61  in order to allow lugs  74  received in receptacles  64  to contact bus straps  70 . Receptacles  64  are configured and positioned such that the open sides of receptacles  64  all face in the same direction and accept lugs  74  from that direction. Receptacles  64  may be configured to form a rectangle, or, as shown, receptacles  64  may be configured to form a staggered line. 
     Lower surface  63  of base plate  61  has channels  66  disposed in it. Channels  66  are configured, positioned, and dimensioned to receive bus straps  70 . Bus straps  70  have first ends  71  and second ends  72 . First ends  71  are secured to load side  56  of distribution power load circuit  34 , while second ends  72  are secured to lower surface  63  of base plate  61 . In a preferred embodiment, distribution power load circuit  34  would be a starter. Openings  67  in the bottoms of receptacles  64  allow bus straps  70  to be in physical contact with lugs  74  when lugs  74  are received in receptacles  64 . 
     Lugs  74  are dimensioned to be snugly received in receptacles  64  thus preventing lugs  74  from turning within receptacles  64 . Lug  74  has ports  76  for receiving output cables  38 . A screw  78  extends into port  76  from an adjacent and perpendicularly disposed surface of lug  74 . This adjacent and perpendicularly disposed surface is positioned on lug  74  to be exposed when lug  74  is received in receptacle  64 . Lug  74  furthermore has a first notched out portion  75  on one side and a second notched out portion  80  on its opposing side. A hole  83  extends from first notched out portion  75  completely through lug  74  to second notched out portion  80 . A fastener (not shown) extends from first notched out portion  75  completely through hole  83  and is received by hole  73  in bus strap  70 . Securement of fastener locks bus strap  70  into place on load terminal assembly  36 . 
     Cable  38  extends out of lug  74  and out of open side of receptacle  64  and away from load terminal assembly  36  so as to be perpendicularly disposed to a longitudinal axis of bus strap  70 . Referring again to FIG. 2, it is clearly shown that cable  38  needs only a single right angle bend to be positioned to pass through an exit port  42  in the bottom of bucket  33 . 
     An alternate embodiment of bus brace  60  is shown in greater detail in FIG.  6 . In this embodiment, bus brace  60  does not have base plate  61 . In either embodiment, bus brace  60  is dimensioned to accommodate a three-phase system wherein the distribution power load circuit  34  is a 3X starter. Bus brace  60  is fabricated of a material sufficient to provide insulating properties as well as rigid support for bus straps  70  during torquing of lug  74 . The distance between receptacles  64  is defined by the thickness of walls  65  of receptacles  64 . This thickness is calculated to minimize the distance between the phases. The open sides of receptacles  64  allow receptacles  64  to accommodate cabling for motor leads, while channels  66 , in conjunction with raised portions on lower surface  63 , provide a clamping force between bus brace  60  and bus strap  70  while retaining the antiturn characteristics of lugs  74 . 
     While this invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.