Abstract:
A lug arrangement for electrically connecting a conductor to a terminal of a circuit breaker. The lug arrangement includes a lug having a lug opening and first and second holes. The lug opening includes an opening for receiving the conductor and a slot for receiving the terminal. The lug arrangement includes a lug screw threadably engaged with the first hole for compressing the conductor against the terminal. Further, the lug arrangement includes a lug retainer for insertion into both the second hole and a third hole formed in the terminal. The lug retainer includes at least one protrusion that is moveable from a first position to a deflected position for enabling insertion of the lug retainer into the second hole. The at least one protrusion is also moveable back to the first position wherein the protrusion engages the second hole to attach the lug retainer to the lug.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/918,618 entitled LUG TERMINAL ASSEMBLY, filed on Dec. 19, 2013, Attorney Docket No. 2013P26550US, which is incorporated herein by reference in its entirety and to which this application claims the benefit of priority. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a lug assembly for an electrical power distribution device, and more particularly, to a lug retention arrangement that includes a lug retainer having at least one moveable protrusion that engages a hole in the lug to attach the lug retainer to the lug and wherein the lug retainer extends through a hole in a terminal to inhibit movement of the lug relative to the terminal. 
       BACKGROUND OF THE INVENTION 
       [0003]    A circuit breaker is used to protect an electric circuit from damage caused by a persistent overcurrent condition, short circuit, fault or other malfunction.  FIG. 1  generally depicts an exemplary three phase circuit breaker  1 . The circuit breaker  1  includes a handle  3  that extends from a housing  5  that is molded from an insulating material. The handle  3  is moveable between on, off and tripped positions to enable an operating mechanism located in the housing  5  to engage and disengage a moveable contact and a stationary contact for each of the three phases in a well-known manner, such that a line terminal  7  and load terminal  9  of each phase are electrically connected. 
         [0004]    The line  7  and load  9  terminals of the circuit breaker  1  are connected to associated wires of the electric circuit by a connector or lug. One type of lug includes a lug body having a conductor hole for receiving a conductor portion of a wire and a threaded hole that is perpendicular to the conductor hole. The lug further includes a lug screw that is threadably engaged with the threaded hole to form a lug assembly. In order to connect a wire to the circuit breaker, an installer strips an end of wire insulation to expose a conductor. The conductor is then inserted into the conductor hole such that, when the installer tightens the lug screw, the body of the screw enters the conductor hole and contacts the conductor. The lug screw is then tightened to compress the conductor against the terminal and to prevent the conductor from being pulled from the lug assembly during normal use. 
         [0005]    Circuit breakers are typically shipped from the factory with one or more lug assemblies that are to be used by an installer at a work site, for example, to connect a circuit breaker to wires of an electric circuit. It is desirable to hold the lugs in a set-up position on the terminals so that they are readily accessible to an installer so as to reduce assembly time. A threaded fastener element may be used to attach a lug to a terminal of a circuit breaker. A disadvantage with this arrangement is that a tool such as a conventional screwdriver, or a pneumatic, electric or hydraulic screwdriver, must be used to tighten the fastener element. In addition, a calibrated torque wrench is needed as part of a quality assurance check to ensure that a desired torque value has been applied to the fastener element. Alternatively, the lug may be molded into the housing of a circuit breaker. A disadvantage with this arrangement is that the lug is not removable from the housing. Therefore, if the lug screw is damaged for example, the entire circuit breaker must be replaced since the lug cannot be removed from the housing. 
       SUMMARY OF INVENTION 
       [0006]    A lug arrangement for electrically connecting a conductor to a terminal of an electrical power distribution device is disclosed. The lug arrangement includes a lug having a lug opening and first and second holes. The lug opening includes a conductor opening for receiving the conductor and a slot for receiving the terminal. The lug arrangement also includes a lug screw threadably engaged with the first hole for compressing the conductor against the terminal. Further, the lug arrangement includes a lug retainer for insertion into both the second hole and a third hole formed in the terminal. The lug retainer includes at least one moveable protrusion wherein the protrusion is moveable from a first position to a deflected position for enabling insertion of the lug retainer into the second hole. The protrusion is also moveable back to the first position wherein the protrusion engages the second hole to attach the lug retainer to the lug. The lug retainer inhibits movement of the lug relative to the terminal. In an alternate embodiment, the lug retainer includes a ring portion that abuts against a surface of the lug. In a further embodiment, the lug retainer is sized to form a press-fit arrangement to attach the lug retainer. 
         [0007]    The respective features of the present invention may be applied jointly or severally in any combination or sub-combination by those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]    The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
           [0009]      FIG. 1  generally depicts a three phase circuit breaker. 
           [0010]      FIG. 2  depicts a lug assembly in accordance with the invention in an exploded view. 
           [0011]      FIG. 3  is a cross sectional side view of the lug assembly. 
           [0012]      FIG. 4  is an enlarged view of balloon section  4  of  FIG. 3 . 
           [0013]      FIG. 5  depicts an alternate embodiment for a lug retainer, 
           [0014]      FIG. 6  depicts the lug retainer of  FIG. 5  inserted in a lug and a terminal. 
           [0015]      FIG. 7  depicts a further embodiment for a lug retainer. 
           [0016]      FIG. 8  depicts a lug for use with the lug retainer of  FIG. 7 . 
       
    
    
       [0017]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
       DETAILED DESCRIPTION 
       [0018]    Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The invention is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or :limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0019]    Referring to  FIG. 2 , a lug arrangement or assembly  10  in accordance with the invention is shown in an exploded view. The assembly  10  includes a substantially cube shaped connector or lug element  12  having top  14  and bottom  16  surfaces and front  18  and rear  20  surfaces. A lug opening  22  extends through the lug  12  between the front  18  and rear  20  surfaces, The lug opening  22  includes a conductor opening section  24  having a curved surface  26  to form a partially rounded shape for receiving a substantially round conductor portion  28  of a wire  30 . In an embodiment, the lug  12  is fabricated from an aluminum alloy. 
         [0020]    The lug opening  22  also includes a terminal opening section  32  oriented along a first axis  34  of the terminal  46  and lug  12 . The terminal opening  32  includes a lower surface  36 , first  38  and second  40  upper surfaces and first  42  and second  44  lateral surfaces to form a slot  33  having a partial rectangular shape for receiving either a line or load terminal  46  having a substantially rectangular shape. The slot  33  enables movement of the lug  12  relative to the terminal  46  along the first axis  34  and inhibits movement of the lug  12  along a second axis  52  transverse to the first axis  34 . In an embodiment, the terminal  46  may be associated with a residential or industrial circuit breaker. Alternatively, the terminal  46  may be associated with other electrical power distribution devices such as contactors, relays, panelboards, switchboards and others. 
         [0021]    Alternatively, the conductor  28  and terminal  46  openings may have other shapes such as oval, square and others for accommodating conductors and/or terminals having corresponding shapes. In  FIG. 2 , the conductor  28  and terminal  46  are depicted as being inserted into the lug opening  22  via the front  18  and rear  20  side surfaces, respectively, although it is understood that the conductor  28  and terminal  46  may be inserted into the lug opening  22  via the rear  20  and front  18  surfaces, respectively. 
         [0022]    The top surface  14  includes a threaded hole  54  for receiving a lug screw  56 . The bottom surface  16  includes a lug aperture  58  for receiving a fastener such as a lug retainer element  60 . Referring to  FIG. 3 , a cross sectional side view of the assembly  12  is shown.  FIG. 4  is an enlarged view of balloon section  4  of  FIG. 3 , Referring to  FIGS. 2-4 , the terminal  46  is inserted into the slot  33  along the first axis  34  such that the lug aperture  58  is aligned, with a terminal aperture  74  formed in the terminal  46 . The lug retainer  60  is then inserted through the lug  58  and terminal  74  apertures, thus inhibiting movement of the lug  12  relative to the terminal  46  along the first axis  34 . In accordance with the invention, the lug retainer  60  is inserted by hand, for example, by using an index finger of a person assembling the lug retainer  60 . 
         [0023]    The lug retainer  60  includes a body portion  62  which extends from an end cap portion  64  that is sized. larger than the lug aperture  58 . The body  62  includes walls  63  having outwardly extending slope portions  66  each forming a protrusion  68 . In an embodiment, the lug retainer  60  includes two protrusions  68 , although it is understood that one protrusion.  68  or more than two protrusions  68  and associated slope portions  66  may be utilized. In order to insert the lug retainer  60 , the body  62  is first aligned with the lug aperture  58 . In a first position, the walls  63  of the lug retainer  60  are oriented substantially parallel to each other such that the protrusions  68  extend beyond an edge  70  of the lug aperture  58 . The walls  63 , slope portions  66  and protrusions  68  are fabricated from a resilient material such as a thermoplastic. Upon insertion of the body  62  into the lug aperture  58 , the slope portions  66  contact the edge  70  of the lug aperture  58 . This causes the walls  63  and slope portions  66  to deflect inwardly toward the second axis  52  such that the protrusions  68  are moved. within the lug aperture  58  and into a second position, thus enabling the body  62  to be inserted into the lug aperture  58 . The body  62  is inserted until the protrusions  68  clear the edge  70  and enter into a recessed portion  72 . of the lug aperture  58 . When this occurs, the protrusions  68  snap back and return to the first position such that the protrusions  68  are located within the recessed portion  72  and the end cap  64  abuts against the bottom surface  16 , thus capturing the lug retainer  60  within the lug  12 , Further, the body  62  extends through the terminal aperture  74 , thus inhibiting movement of the lug  12  relative to the terminal  46  along the first axis  34 . As a result, movement of the lug.  12  along both the first  34  and second  52  axes is inhibited. in another embodiment, the recessed portion  72  may be formed in the terminal aperture  74 . In a further embodiment, a recessed portion  72  may be formed in both the lug  58  and terminal  74  apertures. Alternatively, the body  62  and terminal aperture  74  are configured to form a shrink fit arrangement. 
         [0024]    Thus, the current invention enables attachment of the lug  12  to the terminal  46  by hand and without the use of a tool such as a conventional screwdriver, or a pneumatic, electric or hydraulic screwdriver, In addition, a calibrated torque wrench and a quality assurance check to ensure that a desired torque value has been applied to a retaining element are not needed. This simplifies the process for attaching the retaining element and reduces the likelihood of errors. Further, the amount of time needed to attach the retaining element is reduced, thus saving costs. 
         [0025]    The current invention ensures that lug  12  is attached to the terminal  46  during assembly, packaging and shipping of an electrical power distribution device such as a circuit breaker, for example. In particular, the lug retainer  60  holds an associated lug  12  in a set-up position on a terminal  46  so that the lug  12  is readily accessible to an installer at a work site, for example, therefore reducing assembly time. 
         [0026]    At a work site, an installer may then insert the conductor  28  into the conductor opening  24  and tighten the lug screw  56 . This compresses the conductor  28  between the lug screw  56  and the terminal  46  thus forming electrical contact between the conductor  28  and the terminal  46  and securing the conductor  28 . 
         [0027]    The lug retainer  60  may be kept in place after the conductor  2 . 8  is secured. Alternatively, the lug retainer  60  may he removed by using a tool such as a screwdriver to push out the lug retainer  60 . Thus, the current invention provides advantages with respect to manufacture and assembly and enables a customer to remove the lug retainer  60  as desired. Thereafter, if reassembly is required, a new lug retainer  60  may be reinserted. 
         [0028]    Referring to  FIGS. 5 and 6 , an alternate embodiment for a lug retainer  76  is shown. In this embodiment, the lug retainer  76  includes a ring  78  that projects outwardly from the body  62 . The ring  78  divides the body  62  into first  80  and second  82  body portions. A length of the second body portion  82  corresponds to a distance between the lower surface  36  and bottom surface  16  (see  FIG. 3 ) of a lug  84 . The lug retainer  76  is fabricated from a resilient material such as a thermoplastic material. In a first position, the walls  63  are oriented substantially parallel to each other such that the ring  78  is larger than a lug aperture  86  formed in the lug  84  (see  FIG. 6 ). Upon insertion of the first portion  80  into the lug aperture  86 , the ring  78  contacts an edge  88  of the lug aperture  86 . This causes the walls  63  and ring  78  to deflect inwardly toward the second axis  52  thus enabling upward movement of the ring  78  within the lug aperture  86 . The body  62  is inserted until the ring  78  is moved past the lower surface  36 . When this occurs, the wails  63  and ring  78  snap back to the first position such that the ring  78  abuts against the lower surface  36  and end cap  64  abuts against bottom surface  16 , thus capturing the lug retainer  76  within the lug  84 . Further, the first portion  80  extends into a terminal aperture  92 , thus inhibiting movement of the lug  84  relative to the terminal  46  along the first axis  34 . As a result, movement of the lug  84  along both the first  34  and second  52  axes (see  FIG. 2 ) is inhibited. In a further embodiment, a longer body  62  may be used such that the ring  84  abuts against terminal surface  94 . 
         [0029]    Referring to  FIGS. 7 and 8 , a further embodiment for a lug retainer  96  is shown, In this embodiment, a size D 1  of the body  62  of the lug retainer  96  is configured to be larger than a size D 2  of a lug aperture  98  formed in a lug  100  so as to form a press-fit arrangement. Upon insertion of the retainer  96  into the lug aperture  98 , the body  62  is compressed to form a press-fit that attaches the lug retainer  96  to the lug  100 . The lug retainer  96  is inserted into the lug aperture  98  until the end cap  64  abuts against bottom surface  16 . When this occurs, the body  62  extends through the terminal aperture  92  (see  FIG. 6 ), thus inhibiting movement of the lug  100  relative to the terminal  46  along the first axis  34 . An end  102  of the body  62  includes a chamfer  104  that serves as a lead-in to facilitate insertion of the body  62  into the lug aperture  98 . In an embodiment, the lug retainer  96  is fabricated from a resilient material such as a thermoplastic material. Further, the body  62  may be either hollow or solid. Alternatively, the press-fit arrangement may be formed between the body  62  and the terminal aperture  92  or between the body  62  and both the lug  98  and terminal  92  apertures. 
         [0030]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.