Abstract:
A self-locking assembly for a cable termination having a connector with a step. The self-locking assembly includes a ring having a circumference and a plurality of latches located around the circumference. Each latch is configured to move between a locked position, where the latch is engaged with the step, and an unlocked position, where the latch is disengaged from the step. A sliding ring is configured to move along a portion of the connector and includes a groove, and a support ring is located on the connector and is configured to restrict movement of the sliding ring in at least one direction.

Description:
BACKGROUND 
       [0001]    The present invention relates to a connector design and method of connecting a high-voltage cable to electrical equipment (such as switchgear) in an electricity distribution substation. The term switchgear generally refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. One type of switchgear is “gas insulated switchgear” (“GIS”), where conductors and contacts are insulated by a gas, such as pressurized sulfur hexafluoride gas (“SF 6 ”). Cable terminations suitable to connect a high-voltage cable to a GIS device (often referred to simply as “a GIS”) include fluid-filled cable, dry-type, and pipe-type. 
       SUMMARY 
       [0002]    Although current connectors used to connect cables to switchgear are functional, a connector that is self-locking yet provides relatively easy disconnection of a cable termination from switchgear is desirable 
         [0003]    In one embodiment, the invention provides a self-locking assembly for a cable termination having a connector with a step. The self-locking assembly includes a ring having a circumference and a plurality of latches located around the circumference. Each latch is configured to move between a locked position, where the latch is engaged with the step, and an unlocked position, where the latch is disengaged from the step. The self-locking assembly also includes a sliding ring configured to move along a portion of the connector. The sliding ring has a groove. A support ring is located on the connector and configured to restrict movement of the sliding ring in at least one direction. 
         [0004]    In another embodiment, the invention provides a self-locking assembly including a cable having a cable termination. The cable termination includes a connector with an outer surface, and a slide having a groove. The slide is configured to move along a portion of the outer surface of the connector. The cable termination also includes a stop connected to or integral with the connector and configured to restrict movement of the slide in at least one direction. A latch is configured to engage the outer surface of the cable termination in a locked state and engage the groove of the slide in a transition state. 
         [0005]    In another embodiment, the invention provides a method of operating a self-locking assembly for a cable termination having a connector with an outer surface and a step. The self-locking assembly includes a latch, a biasing mechanism (such as a spring) biasing the latch towards the outer surface of the connector, a slide with a groove and configured to slide along a portion of the outer surface of the connector, and a stop coupled to the connector and configured to restrict movement of the slide in at least one direction. The method includes moving the cable termination in a first direction, moving the latch opposite to the bias of the biasing mechanism, disengaging the latch from the outer surface of the connector as a result of moving the latch, engaging the groove of the slide with the latch as a result of the biasing mechanism biasing the latch, moving the cable termination in a second direction opposite to the first direction, engaging the step with the slide, and disengaging the latch from the groove as a result moving the cable termination in the second direction and engaging the step with the slide. 
         [0006]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a cable termination coupled to a GIS. 
           [0008]      FIG. 2  is a cross-sectional view of the cable termination coupled to the GIS and illustrates a self-locking cable termination assembly. 
           [0009]      FIG. 3  is a detailed view of the cross-section in  FIG. 2 , illustrating the self-locking cable termination assembly in more detail. 
           [0010]      FIG. 4A  is a partial view of the self-locking cable termination assembly in a first position. 
           [0011]      FIG. 4B  is a partial view of the self-locking cable termination assembly in a second position. 
           [0012]      FIG. 4C  is a partial view of the self-locking cable termination assembly in a third position. 
           [0013]      FIG. 4D  is a partial view of the self-locking cable termination assembly in a fourth position. 
           [0014]      FIG. 5  is a perspective view of the self-locking cable termination assembly in a locked position. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0016]      FIG. 1  illustrates a portion of a cable  10 . A cable termination  15  is attached to and surrounds part of the cable  10 . The cable termination  15  includes a base plate  20  and an entrance housing  25 . The cable termination  15  also includes a portion of a self-locking assembly  22 . Part of the self-locking assembly  22  extends into a portion of a GIS  35 . The self locking assembly  22  is illustrated in  FIGS. 2-5  and will be described in greater detail below. The GIS  35  includes, among other things, a box insulator  40  that encloses components of the self-locking assembly  22 . The GIS  35  also includes an insert  42 . The cable termination  15  is detachably coupled or connected to the GIS  35 . Although the illustrated construction describes and illustrates the cable termination  15  as being detachably connected to a GIS, it is to be understood that embodiments of the self-locking assembly could be used to connect cables to other types of switchgear or electrical equipment. 
         [0017]      FIG. 2  is a cross-sectional view of the cable  10 , the GIS  35 , and the self-locking assembly  22 . In the illustrated construction, the cable  10  includes a first end  45 . A cable connector  50  is connected to the first end  45 . The cable connector  50  is part of the cable termination  15 . In some cases, the cable  10  and the connector  50  are made from the same material. However, in other embodiments the cable  10  and connector  50  are manufactured of different materials. The connector  50  includes a head portion  55  and a support portion  60 . The support portion  60  encloses, and is connected to the first end  45  of the cable  10 . Each of the head portion  55  and the support portion  60  are substantially cylindrically shaped. The head portion  55  has a larger diameter than the support portion  60 . The head portion  55  and the support portion  60  form a step  65 . The step  65  is configured to receive one or more latches  70 , as further explained below. 
         [0018]    A stop  75  (which in the illustrated embodiment takes the form of a support ring) is fixedly connected to the support portion  60  of the connector  50 . A slide  80  (which in the illustrated embodiment is a sliding ring) is movably or slidingly fit to the support portion  60  of the connector  50  between the support ring  75  and the step  65 . The sliding ring  80  is configured to slide along the surface of the support portion  60  between the step  65  and the support ring  75 . In the illustrated construction, the support ring  75  is below the sliding ring  80  such that the support ring  75  restricts motion or movement of the sliding ring  80  that might be caused by forces acting on the sliding ring  80  (e.g., gravity). 
         [0019]    As illustrated in  FIG. 2 , the insert  42  of the GIS  35  includes an outer shell  83  defining a cavity  100  therein. Within the cavity  100 , the outer shell  83  encloses a metal connector  85 . The metal connector  85  includes an annular groove  90 . The groove  90  of the connector  85  holds protrusions  91  from a number of connecting portions  92  forming a hollow cylinder  95 . The annular groove  90  receives the protrusions  91  of the connecting portions  92  and, as a consequence, partially supports the cylinder  95 . The connecting portions  92  of the cylinder  95  include four annular channels  105  that receive support springs  110 . The two upper support springs  110  (with respect to  FIG. 2 ) help support the connecting portions  92  against the groove  90  of the metal connector. Similarly, the two lower support springs  110  bias the connecting portions  92  towards the hear portion  55 . Accordingly, a lower portion  117  of the connecting ring  95  receives and/or contacts the head portion  55  of the connector  50  such that a separation space or gap  120  is formed between the lower surface of the metal connector  85  and the upper surface of head portion  55 . 
         [0020]    As illustrated in  FIGS. 2 and 3 , the outer shell  83  of the insert  42  contacts an insulator  125  of the box insulator  40 . The insulator  125  is supported by a metal insert  130 . The metal insert  130  has an outer surface  132  enclosed by an epoxy cover  135 . The metal insert  130  includes a cavity  140  that receives the connector  50 , and supports a latch mounting structure or latch mount  145 . The latch mount  145  holds the latches  70  (two latches are illustrated in  FIGS. 2 and 3 ). The latch mount  145  also includes a threaded ring  150  with fasteners  155  (e.g., bolts, screws, etc.) extending therethrough and fastening the threaded ring  150  to the insulator  125 . 
         [0021]    As illustrated in  FIG. 5 , the threaded ring  150  supports each one of the latches  70  with a pin and spring assembly  160 . Each pin and spring assembly includes a spring  161  and a through bolt or pin  162  that extends through a pair of supports  164 . The latch  70  is positioned between the pair of supports  164  and the pin  162  extends through an aperture in the latch  70 . The spring  161  biases the latch  70  to cause a hook  175  of each latch  70  to sit in the step  65 . Each latch  70  also includes an upper portion  171  and a middle portion  172  connecting the upper portion  171  to the hook  175 . In the illustrated construction, the upper portion  171  of the latch  70  snuggly fits between the supports  164  allowing only rotational movement of the latch  70  with respect to the pin  162 . Other configurations, however, can include the latch  70  with more than one dimension of freedom or movement. The spring  161  is fixedly mounted on opposite ends of the pin  162  and includes a middle portion  168  that engages the latch  70 . 
         [0022]    The pin and spring assembly  160  and latches  70  are components of the self-locking assembly  22 . As described in further detail below, the latches  70  can be moved from a locked state or position to an unlocked state or position. In the locked position (illustrated in  FIGS. 2 ,  3 ,  4 A and  5 ), the spring  161  causes the latches  70  to engage the step  65  and support the cable  10  via the connector  50 . This holds the connector  50  in place and prevents it from disengaging from the GIS  35 . As a consequence, a path is provided so that electric current can flow between the cable  10  and the GIS  35  via the connector  50 , the connecting ring  95 , and the metal connector  85 . When the sliding ring  80  is moved appropriately, the latches  70  move from the locked position to an unlocked position (as illustrated in  FIG. 4D , and further explained below). Other support or connection assemblies may be located along the cable  10  and GIS  35  to support or maintain a connection between the cable  10  and the GIS  35 . 
         [0023]      FIGS. 4A through 4D  illustrate a portion of the self-locking assembly  22  and the latches  70  in the locked position ( FIG. 4A ), transition positions (illustrated in  FIGS. 4B and 4C ), and the unlocked position ( FIG. 4D ). As indicated above, the self-locking assembly  22  includes the spring  161 , the latches  70  (only one latch  70  is illustrated in  FIGS. 4A through 4D ), the support ring  75 , and the sliding ring  80 . In the locked position, the hook  175  of the latch  70  engages the step  65  of the connector  50 . The spring  161  (illustrated in  FIG. 5 ) biases the latch  70  towards the connector  50  to secure the latch  70  against the connector  50 . In the locked position, the sliding ring  80  generally rests on the support ring  75 . However, friction between the sliding ring  80  and the connector  50  may be sufficient to maintain the sliding ring  80  in other positions between the support ring  75  and the latch  70  while the latch  70  is in the locked position. 
         [0024]      FIGS. 4B and 4C  illustrate two transition positions of the cable  10  and the self-locking assembly  22 . To unlock the latches  70 , the cable  10  is moved to disengage the cable  10  from the GIS  35 . As illustrated in  FIG. 4B , the cable is moved in an upward direction (with respect to  FIGS. 4A through 4D ) as indicated by arrow  180 . The upward motion of the cable  10  causes a first contact surface  185  of the sliding ring  80  to engage a second contact surface  190  of the latch  70 . As a result of the contact between the surfaces  185  and  190  and continued movement of the cable  10 , the latch  70  is pushed outwardly against the bias of the spring mechanism  160 . Subsequently, the hook  175  of the latch  70  engages a receiving groove or aperture  195  of the sliding ring  80 . The gap  120  provides sufficient space to allow movement of the cable  10  and, in particular, the connector  50  toward the metal connector  85  such that the latches  70  can move to the unlocked position. 
         [0025]    Subsequent to engaging the receiving groove  195  with the hook  175 , the cable  10  is moved downwardly (with respect to  FIGS. 4A through 4D ) as indicted by arrow  200  in  FIGS. 4C and 4D . As the cable is move downwardly, the latch  70  remains engaged to the sliding ring  80  such that the sliding ring  80  prevents the latch from contacting the surface of the connector  50 , and, therefore, the step  65 . In addition, the sliding ring  80  remains static with respect to the cable  10  such that the support ring  75  moves with respect to the latch  70  and the sliding ring  80 . The sliding ring  80  also includes a shoulder or lip  205  formed radially inwardly with respect to the first contact surface  185 . The lip  205  engages the step  65 , as illustrated in  FIG. 4C . In the illustrated construction, the lip  205  is substantially parallel with the surface defining the step  65 . In addition, the first contact surface  185  is curved and angled with respect to the lip  205  and is separated from the lip  205  by a substantially vertical wall  210 . In other constructions, the sliding ring  80  and the latch  70  can include other suitable structures promoting selective engagement and disengagement of the sliding ring  80  and the latch  70 . 
         [0026]    To complete movement of the latches  70  to the unlocked position, the cable  10  is moved downward further. The curved first contact surface  185  causes the latch  70  to slide as the cable  10  moves downwardly and the sliding ring  80  contacts the step  65 . As a result, the latch  70  disengages the sliding ring  80  and the spring  161  biases the latch  70  towards the surface of the head portion  55  of the connector  50  without engaging the step  65  (as illustrated in  FIG. 4D ). Accordingly, the connector  50  and, consequently, the cable  10  are disengaged from the GIS  35 . 
         [0027]    To lock the cable  10  in the GIS  35  with the latches  70 , the latches  70  are moved from the unlocked position to the locked position. The cable  10  is inserted into the GIS  35  so that the outer surface of the connector  50  contacts the latch  70  (as illustrated in  FIG. 4D ). The cable  10  is inserted so that the step  65  moves past the hook  175 . The inner surface of the hook  175  then engages the step  65 . In  FIGS. 4A through 4D , the latch  70  is illustrated as rotating between the unlocked and locked positions. In other constructions, the latch  70  can be configured to move translationally and rotationally to engage and disengage the connector  50 . 
         [0028]    Various features and advantages of the invention are set forth in the following claims.