Patent Publication Number: US-6984791-B1

Title: Visual latching indicator arrangement for an electrical bushing and terminator

Description:
RELATED INVENTION 
   This application is a continuation of U.S. Ser. No. 10/198,963, filed Jul. 22, 2002, now abandoned; which is a continuation of U.S. Ser. No. 08/821,760, filed Mar. 20, 1997, now U.S. Pat. No. 6,504,103; which is a continuation of U.S. Ser. No. 08/262,460, filed Jun. 20, 1994, now abandoned; which is a continuation-in-part of U.S. Ser. No. 08/038,335, filed Mar. 10, 1993, now abandoned, all of which are incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to the interconnection of electrical distribution elements and, in particular, to the interconnection between a loadbreak elbow terminator and a bushing. 
   Electrical distribution equipment, such as a deadfront switch gear arrangement, typically includes fixed electrical bushings which are to be connected to external electrical cables. The fixed bushings are mounted in a wall of the electrical equipment and have their outer ends arranged to be connected to the cables. 
   One way of achieving this connection is by inserting an elbow terminator onto the bushing, the terminator being coupled to the cable. The elbow terminator, which typically comprises a tapered socket in which an electrical probe is mounted, is intended to be inserted onto the fixed bushing such that a tapered tongue of the bushing enters the socket. In so doing, a conductive tube disposed within the tongue makes electrical connection with the probe, thereby connecting the cable to the fixed bushing. 
   The elbow terminator is secured to the bushing by means of a latching ring disposed at an inner end of the socket. That latching ring snaps into an annular latching groove formed in the outer periphery of the leading end of the tongue when the elbow terminator is pushed onto the fixed bushing. 
   The elbow terminator is maneuvered onto the bushing by means of a hand-held shotgun stick which grabs a hook eye affixed to the elbow terminator. It may occur, however, that the tongue does not completely enter the socket, whereby the latching ring does not tightly grip the latching socket. That unlatched condition, which is potentially dangerous, is difficult for the operator to visually detect, especially since the operator will likely be standing remotely (e.g., at least three to five feet) from the terminator and bushing, for safety reasons. 
   It would therefore be desirable to facilitate the ability of the operator to detect an unlatched condition, especially when standing remotely of the terminator and bushing. 
   SUMMARY OF THE INVENTION 
   The present invention relates to the combination of an electrical terminator and an electrical bushing component. The terminator includes a socket, and the bushing component includes a tongue receivable in the socket to electrically interconnect the terminator and bushing. The tongue and socket include a latching arrangement for positively latching the bushing component and terminator together when the tongue enters the socket to a prescribed depth. First and second visual indicators are disposed on outer peripheries of the bushing component and the terminator, respectively. The first and second visual indicators are arranged so that when the terminator is longitudinally inserted onto the bushing, the first and second indicators longitudinally approach one another sufficiently to at least become radially aligned with one another in order to provide a visual indication of positive latching. One of the first and second indicators is situated radially outside of the other of the indicator and is visible when the combination is viewed in a radially inward direction passing through the one indicator. 
   In another aspect of the invention, an indicator is defined by a color band formed on one of the terminator and bushing component (preferably on the bushing component) and is arranged to be radially covered by an indicator in the form of a covering portion of the other of the terminator and bushing component (preferably the terminator) when the tongue enters the socket to the prescribed depth, thereby providing a visual indication of positive latching. 
   The present invention also relates to an electrical bushing component which possesses the color band, and also to a method of connecting an electrical terminator to an electrical bushing component which involves causing the color band to be covered when positive latching occurs. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof in connection with the accompanying drawings in which like numerals designate like elements and in which: 
       FIG. 1  is a side elevational view of an elbow terminator and a bushing according to a first preferred embodiment of the invention, in a separated condition, and with the elbow terminator depicted in vertical section; 
       FIG. 2  is a view similar to  FIG. 1  after the terminator has been inserted onto the bushing, a portion of the terminator being broken away; 
       FIG. 3  is a longitudinal sectional view taken through the bushing depicted in  FIG. 1 ; 
       FIG. 4  is a plan view the terminator and bushing after they have been joined together; 
       FIG. 5  is a side elevational view of an elbow terminator and a bushing according to a second embodiment of the invention, in a separated condition, and with the elbow terminator partially broken away; and 
       FIG. 6  is a view similar to  FIG. 5  of the second embodiment, after the terminator has been inserted onto the bushing. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
   Depicted in  FIG. 1  is a loadbreak elbow terminator  10  and a bushing  12  adapted for connection therewith. The bushing can be of a type which is fixed to a stationary panel such that a tongue  22  is externally exposed. The elbow terminator includes a socket  14  formed in an electrical insulative material  16 . The socket  14  includes a tapered portion  13  and merges into a cylindrical portion  15 . Extending centrally along the socket is a probe  18  which carries an arc follower  20 . The probe  18  is electrically connected to a cable  19 . 
   The tongue  22  is configured to make an interference fit within the socket  14 . Adjoining the tongue  22  is a cylindrical enlargement  24  configured to enter the cylindrical portion  15 . The tongue  22  is hollow and includes a contact tube  26  (see  FIG. 3 ) in which are disposed an arc interrupter  28  and a contact sleeve  30 . 
   An end of the tongue  22  includes a latching groove  32 . When the elbow terminator is pushed onto the bushing  12 , the latching groove  32  receives, by snap fit, a latching ring  34  formed on a semiconducting insert  35  at an inner end of the socket  14 . In that fashion, the bushing becomes secured to the elbow terminator. 
   As thus far described, the elbow terminator  10  and bushing  12  are conventional. The elbow terminator is maneuvered onto the bushing  12  by a conventional shotgun stick (not shown) which is manipulated manually by an operator. The shotgun stick includes a hook which grips a hook eye  38  carried by the elbow terminator. As explained earlier, it may occur that the tongue does not fully enter the socket, so that the latching ring  34  does not completely enter the latching groove  32 . In that event, the bushing could become dislodged from the elbow terminator  10 . 
   That problem is avoided by the present invention which involves the addition of a visual indicating arrangement which visually indicates when the tongue has entered the socket to a sufficient longitudinal depth to ensure latching. The visual indicating arrangement comprises cooperative visual indicators positioned on the busing and elbow terminator such that the locations of the visual indicators relative to one another in the longitudinal direction is readily visible to the operator. When the visual indicators attain a certain longitudinal relationship, it is ensured that positive latching has occurred. The edge  56  is visible when the bushing  12  is viewed in a radially inward direction D passing through the edge  56 , as is evident from  FIGS. 3 and 4 . 
   The visual indicators comprise an indicator gauge  40  disposed exteriorly on the bushing  12 , and an indicator ring  42  disposed exteriorly on the elbow terminator  10 . The indicator ring  42  encircles the outer periphery of the elbow terminal at the entrance to the cylindrical portion  15  and forms a shoulder  44  which defines a mark in the form of an annular edge indicator or witness line  46 . 
   The indicator gauge  40  includes an annular base portion  48  which encircles the outer periphery of the busing at a location remote from the leading end thereof, i.e., remote from the latching groove  32  for the preferred version. 
   Projecting radially inwardly from an inner diameter of the base portion  48  is an annular ridge  50  configured to snap into a corresponding annular depression formed in the bushing. The semiconductive ground shield  52  could be modified to provide an appropriate surface in which the annular depression can be formed. Alternatively, the semiconductive ground shield  52  could be modified to include the spaced tabs  54  as an integral, i.e., one-piece, part. 
   Projecting longitudinally from the base  48  is a plurality of circumferentially spaced tabs  54 . Each tab  54  includes a beveled free end  55  which defines a mark in the form of a circumferentially extending indicator edge  56  at a radially inner portion of that free end  55 . The tabs  54  are of a prescribed length so that when the tongue  22  enters the socket  14  to a longitudinal depth sufficient to ensure positive latching by the latching ring  34  and latching groove  32 , the indicator edges  46 ,  56  will either be radially aligned with one another (as shown in  FIG. 4 ) or pass one another (i.e., the indicator edges  56  would be disposed to the left of the indicator edge  46  in  FIG. 4 ). Thus, an operator can tell, merely by a visual inspection of the relative longitudinal locations of the edges  56 ,  46  whether positive latching has occurred. 
   The beveling of the free ends  5 S of the tabs makes it easier for the operator to observe the indicator edges  56 . By forming the tabs  54  on an annular base  48 , the tabs can be conveniently mounted as a unit on the bushing. It will be understood by those skilled in the art that, depending upon the configuration of the outer periphery of the bushing, it may be possible to mold the bushing with tabs in lieu of providing a snap-on base  48  to which the tabs are mounted. 
   It may also be desirable to reverse the parts, i.e., to provide the gauge tabs  54  on the terminator and provide the indicator ring  42  on the bushing. 
   The indicator ring  42  could comprise an integral, one-piece portion of the terminator housing, or a separately attached piece. 
   It may be desirable to color the gauge tabs  54  differently from the indicator ring  42  in order to contrast the edges  46 ,  56  as much as possible and thereby, facilitate a proper observation by the operator. 
   While in the disclosed preferred embodiment the indicator gauge  40  is disposed on a bushing, it will be appreciated that the indicator gauge could also be disposed on a bushing insert which is to be mounted to a bushing. Bushings (such as, for example, LBC devices, standoffs, and one-piece bushings) and bushing inserts can be generically referred to as “bushing components”. 
   A second embodiment of the invention, depicted in  FIGS. 5 and 6 , involves a loadbreak elbow terminator  100  and a bushing  112 , wherein a visual indicator or mark  114  is provided on the bushing to cooperate with a visual indicator  116  provided on the terminator. 
   The visual indicator  116  on the terminator is defined by an end portion or end flange of the terminator which surrounds the cylindrical portion  115  of the terminator socket into which a tongue  118  of the bushing is to be inserted. 
   The visual indicator  114  on the bushing is in the form of an annular color band of width W formed directly on the outer surface of the tongue  118  of the bushing. The color of the band  114  sharply contrasts with that of an adjacent portion  120  of the tongue  118  and also with that of the outer surface of the flange  116 . Preferably, the band color is of a highly visible nature, such as a bright dayglow color like yellow, orange, lime green, etc., which is readily visible from at least a three to five foot distance. The color of an adjacent portion of the tongue would be formed of a contrastingly dark color such as brown or gray. 
   The band  114  forms an edge indicator or witness line  122  at its junction with the adjacent portion  120  of the tongue. Likewise, the end flange  116  of the terminator defines an edge indicator  124 . 
   The relationship between the edge indicators  122 ,  124  is such that when the terminator is longitudinally inserted onto the bushing sufficiently far for positive latching to occur in the manner described earlier herein, the edge indicators  122 ,  124  will have longitudinally approached one another sufficiently to be at least radially aligned with one anther. That is, when positive latching has occurred, the color band  114  will be completely disposed within the socket portion  115  and no longer visible. 
   That indication will be discernable by an operator who views the bushing in a radial direction (i.e., radially with reference to the longitudinal axis thereof), from a distance of at least three to five feet. This enables the operator to maintain a safety distance while determining that latching has occurred. 
   The color band  114  can be applied in any suitable manner, preferably by applying a colored ink by means of a roller traveling around the outer periphery of the tongue. The band  114  is preferably circumferentially continuous, but it could be interrupted as well, since it is only required that the band be at least partly visible when there is no positive latching, and be invisible when there is positive latching. 
   The radial distance between the color band  114  and the longitudinal center axis of the tongue is larger than the radial distance between the axis and all portions of the outer circumferential surface of the tongue  118  situated between the color band and a free end  130  of the tongue, as is clear from  FIG. 5 . As a result, the color band can easily be viewed by an operator who is located to the left of the bushing  112  in  FIG. 5  while applying the terminator. In particular, the outer circumferential surface of the tongue  118  includes a first portion  131  extending from the free end  130 , and a second portion  132  disposed radially outwardly of the first portion and separated from the first portion by a radial wall  134  of the tongue which is oriented perpendicular to the center axis of the tongue. The color band  114  is disposed flush on the second portion.