Patent Publication Number: US-8986034-B2

Title: Restraint and lock for electrical connector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119, based on U.S. Provisional Patent Application No. 61/670,828 filed Jul. 12, 2012, the disclosure of which is hereby incorporated by reference herein 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to electrical cable connectors, such as connectors for joining two or more electrical cables, loadbreak connectors, and deadbreak connectors. More particularly, aspects described herein relate to an electrical cable connector that reduces misalignment and/or slippage of connected components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional diagram illustrating a power cable splicing assembly consistent with implementations described herein; 
         FIG. 2  is a schematic cross-sectional diagram illustrating a three-way yoke of  FIG. 1  consistent with implementations described herein; 
         FIG. 3  is an exploded, schematic, partial cross-sectional diagram illustrating a portion of the three-way yoke and one of the cable assemblies of  FIG. 1 ; 
         FIG. 4A-4C  are top views of a portion of the three-way yoke of  FIG. 1  according to different implementation described herein; 
         FIG. 5  is a schematic cross-sectional diagram illustrating a cable assembly according to another implementation described herein; and 
         FIGS. 6A-6C  are schematic, cross-sectional diagrams illustrating the interface between the receptacle insert of  FIG. 5  and the tubular extension of  FIGS. 4A-4C . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. 
       FIG. 1  is a schematic cross-sectional diagram illustrating an exemplary power cable splicing assembly  100  consistent with implementations described herein. As shown in  FIG. 1 , power cable splicing connector  100  may include a three-way (e.g., a “Y”) yoke  102  for enabling connection of power cables assemblies  104 - 1 ,  104 - 2 , and  104 - 3  (collectively “power cable assemblies  104 ,” and generically “power cable assembly  104 ”). For example, power cable assembly  104 - 1  may include a supply cable and power cable assemblies  104 - 2  and  104 - 3  may include load cables. Although described for use with yoke  102 , other types of power cable connectors may be configured in accordance with implementations described herein, such as four-way yoke connectors, two-way connectors, etc. 
     In one implementation, yoke  102  of power cable splicing connector  100  may include a central conductor  106  (also referred to as bus bar  106 ) and number of taps  108 - 1  to  108 - 3  (collectively “taps  108 ,” and generically “tap  108 ”). Central conductor  106  may be formed of a suitably conductive material, such as copper, aluminum, or other conductive alloy. Further, as shown in  FIG. 1 , central conductor  106  may include bus extensions  110 - 1  to  110 - 3  (collectively “bus extensions  110 ,” and generically “bus extension  110 ”) that project from respective taps  108  in yoke  102 . As described in additional detail below, central conductor  106  may connect each of power cable assemblies  104  to each other power cable assembly  104 , such that power applied to one cable is transferred to each other cable. 
     Bus extensions  110  may be configured to receive connector portions of power cables  104  in the manner consistent with embodiments described herein. For example, each bus extension  110  may include a spade portion  112  (also referred to as “yoke spade portion  112 ”) having a threaded bore  114  (shown in  FIG. 2 ) extending therethrough. Each power cable assembly  104  may be prepared by connecting a power cable  115  to a crimp connector  116 . Crimp connector  116  may include a substantially cylindrical assembly configured to receive a cable conductor  118  of power cable  115  therein. During preparing of power cable assembly  104 , a portion of crimp connector  116  may be physically deformed (e.g., crimped) to fasten crimp connector  116  to cable conductor  118 . 
     Crimp connector  116  may include a forward spade portion  120  (shown in  FIG. 3 ) (also referred to as “crimp connector spade portion  120 ”) configured to be securely fastened to a spade portion  112  of bus extension  110  of central conductor  106 . For example, forward spade portions  120  of each crimp connector  116  may include an opening  121  therein (shown in  FIG. 3 ) configured to align with threaded bore  114  in yoke spade portion  112 . A threaded fastener  122  may be inserted through forward spade portion  120  and into threaded bore  114  of yoke spade portion  112  to secure crimp connector  116  to central conductor  106 . 
     As shown in  FIG. 1 , each of the prepared power cable assemblies  104  may further include an adapter  124  disposed rearwardly relative to crimp connector  116 . Adapter  124  may be affixed to power cable  115  and may provide a frictional engagement with a rearward portion of a respective cable receptacle  126 - 1  to  126 - 3  (collectively “cable receptacles  126 ,” and generically “cable receptacle  126 ”). In one implementation, adapter  124  may be formed of an insulative material, such as rubber, a thermoplastic, or epoxy. 
     As shown in  FIG. 1 , each tap  108  includes a cable receptacle interface  127  that includes a substantially cylindrical flange or cuff portion configured to frictionally engage cable receptacle  126 . For example, an inside diameter of a forward end of cable receptacle  126  may be sized to frictionally engage the cuff portion of interface  127 . Each cable receptacle  126  may be substantially cylindrical and may be configured to surround and protect an interface between power cable assembly  104  and bus extensions  110 . In one implementation, for example, cable receptacle  126  may provide a weather-resistant barrier for the interface between power cable assembly  104  and bus extensions  110 . 
     Yoke  102  may include a semi-conductive outer shield  128  formed from, for example, a peroxide-cured synthetic rubber, commonly referred to as EPDM (ethylene-propylene-dienemonomer). Within shield  128 , yoke  102  may include an insulative inner housing  130 , typically molded from an insulative rubber or epoxy material. Central conductor  106  may be enclosed within insulative inner housing  130 . 
     Regarding cable receptacles  126 , each cable receptacle  126  may include an EPDM outer shield  132  and an insulative inner housing  133 , typically molded from an insulative rubber or epoxy material. Cable receptacle  126  may further include a conductive or semi-conductive insert  134  having a longitudinal bore therethrough. Upon assembly, cable receptacle  126  surrounds the interface between power cable assembly  104  and bus extension  110 . In one implementation, forward ends of insert  134  and outer shield  132  may be configured to frictionally engage a portion of yoke inner housing  130  at each tap  108  upon assembly of splicing connector  100 , thereby ensuring the electrical integrity of splicing connector  100 . 
     In some instances, momentary high current surges in a high voltage environment may initiate bending forces in power cable assembly  104 . These bending forces may overcome the frictional engagement between the yoke inner housing  130  at tap  108  which could result in a compromise of the weather-resistant barrier. In other instances, air expansion within the area inside cable receptacle  126  may provide a similar effect. Thus, consistent with implementations described herein, tubular extensions  140 - 1  to  140 - 3  (collectively “tubular extensions  140 ,” and generically “tubular extension  140 ”) may extend from a respective bus extension  110 - 1  to  110 - 3 . 
     As shown in  FIG. 1 , tubular extension  140  may be configured to fit within the inside diameter of insert  134  of cable receptacle  126  and over yoke spade portion  112  and crimp connector  116  without interference. Thus, tubular extension  140  may have different wall thickness depending on the particular size and available clearances at the interface of crimp connector  116  and insert  134 . Tubular extension  140  may include a metallic material, such as aluminum, or a plastic material, such as reinforced fiberglass. In one implementation, tubular extension  140  may be made from the same material as central conductor  106 . Tubular extension  140  may generally include a cylindrical shape or another tube-like cross-section (e.g., octagonal, hexagonal, etc.) to match the shape of bus extension  110 . Tubular extension  140  may be secured to bus extension  110  by welding, by a threaded connection, or by another type of connection. 
     When yoke  102  and power cable assembly  104  are fully connected (e.g., crimp connector spade portion  120  and yoke spade portion  112  are secured together and cable receptacle  126  is slid fully forward), tubular extension  140  supports cable receptacle  126  to prevent misalignment of power cable assembly  104  with yoke  102  and/or to prevent movement of power cable assembly  104  (e.g., rotation or bending relative to yoke  102 ) due to temporary high current. 
       FIG. 2  is a schematic cross-sectional diagram illustrating three-way yoke  102 .  FIG. 3  is an exploded, schematic, partial cross-sectional diagram illustrating a portion of the three-way yoke  102  and one of the power cable assemblies  104 . Referring collectively to  FIGS. 2 and 3 , tubular extension  140  may include an access hole  142  and an exit hole  144 . Tubular extension  140  may be affixed to bus extension  110  so that access hole  142  and exit hole  144  may align with bore  114  (e.g., to permit insertion of threaded fastener  120  into bore  114 ). Access hole  142  may be sized to permit fastener  122 , a disc spring  146 , and a washer  148  to pass through with sufficient clearance to enable assembly of threaded fastener  122  through forward spade portion  120  and yoke spade portion  112 . More particularly, when assembled, access hole  142 , exit hole  144 , and bore  114  may align with opening  121  to permit threaded fastener  122  to be inserted and engage corresponding threads in bore  114 . Exit hole  144  may be provided to clear threaded fastener  122  after assembly (e.g., to allow fastener  122  to extend past the end of bore  114 ). 
       FIGS. 4A ,  4 B, and  4 C are top views of a portion of the three-way yoke  102  according to different implementation described herein.  FIGS. 4A and 4C  illustrate a hook-shaped retention ring  150  on a distal end of tubular extension  140 , while  FIG. 4B  illustrates a flared retention ring  152  on the distal end of tubular extension  140 . As described further herein, hook-shaped retention ring  150  or flared retention ring  152  may be used in a latching arrangement with receptacle  126  to restrain outer shield  132  of receptacle  126  from sliding back from shield  128  of yoke  102 . 
     Referring to  FIG. 4A , hook-shaped retention ring  150  may be formed, for example, by machining away a portion of an outer surface of tubular extension  140  such that a ring-shaped lip  154  extends beyond the machined surface  156 . Referring to  FIG. 4B , flared retention ring  152  maybe formed, for example, by turning out the circumference of the distal end of tubular extension  140 . Thus, retention ring  152  may form an interference surface  158  that may be used, for example, in a latching arrangement described further herein. Referring to  FIG. 4C , hook-shaped retention ring  150  may be formed by machining away a smaller portion (relative to that of  FIG. 4A ) of the outer surface of tubular extension  140  such that a ring-shaped lip  154  extends beyond the machined surface  156  and a larger diameter outer surface  157  extends to the proximal end of tubular extension  140 . 
       FIG. 5  is a schematic cross-sectional diagram illustrating power cable assembly  104  according to another implementation described herein. In the configuration of  FIG. 5 , cable receptacle  126  is slid back from crimp connector  116  (e.g., prior to connection of power cable assembly  104  and bus extension  110 ). As shown in  FIG. 5 , insert  134  of cable receptacle  126  may include a latching ring  160 . Latching ring  160  may extend radially along the inner circumference of insert  134 . In one implementation, latching ring  160  may be an integrally molded piece with insert  134 . In another implementation, latching ring  160  may be affixed to, or otherwise formed on, an inner surface of insert  134 . Latching ring  160  may include a forward sloped surface  162  and a rear engagement surface  164 . 
       FIGS. 6A ,  6 B, and  6 C are schematic, cross-sectional diagrams illustrating the interface between receptacle insert  134  with latching ring  160  and tubular extension  140 . In each of  FIGS. 6A-6C , cable receptacle  126  is slid over crimp connector  116  and tubular extension  140  (e.g., after connection of power cable assembly  104  and bus extension  110 ).  FIGS. 6A and 6C  show the interface between retention ring  150  and latching ring  160 , while  FIG. 6B  shows the interface between retention ring  152  and latching ring  160 . Generally, latching ring  160  may be positioned along cable receptacle  126 /insert  134  to engage retention ring  150  or retention ring  152  when cable receptacle  126  is fully closed over crimp connector  116 . Retention rings  150  or  152  and latching ring  160  may be generally configured to interlock to retain cable receptacle  126  in a position to maintain a weather-resistant barrier for the interface between power cable assembly  104  and bus extension  110 . 
     Latching ring  160 , insert  134 , and/or cable receptacle  126  may have elastic properties to both allow for sealing of the interface between power cable assembly  104  and yoke  102  and to permit latching ring  160  to be forced over retention ring  150  and/or retention ring  152 . Referring to  FIG. 6A , as cable receptacle  126  is slid over tubular extension  140  (e.g., toward yoke  102 ), latching ring  160  may slide over retention ring  150 . Forward sloped surface  162  may act as an inclined plane to translate axial forces applied to cable receptacle  126  and force latching ring over retention ring  150 . In one implementation, retention ring  150  may include a corresponding slope to guide forward sloped surface  162  over retention ring  150 . When cable receptacle  126  is fully inserted over tubular extension  140 , latching ring  160  will pass over retention ring  150  so that rear engagement surface  164  will contact lip  154  if cable receptacle  126  is forced away from yoke  102 . 
     Referring to  FIG. 6B , as cable receptacle  126  is slid over tubular extension  140  (e.g., toward yoke  102 ), latching ring  160  may slide over retention ring  152 . Forward sloped surface  162  may act as an inclined plane to translate axial forces applied to cable receptacle  126  and force latching ring over retention ring  152 . When cable receptacle  126  is fully inserted over tubular extension  140 , latching ring  160  will pass over retention ring  152  so that rear engagement surface  164  will contact interference surface  158  if cable receptacle  126  is forced away from yoke  102 . 
     Referring to  FIG. 6C , cable receptacle  126  is slid over tubular extension  140  (e.g., toward yoke  102 ) and latching ring  160  may slide over retention ring  150  similar to that described above with respect to  FIG. 6A . Eventually, latching ring  160  will pass over retention ring  150  so that rear engagement surface  164  will contact lip  154  if cable receptacle  126  is forced away from yoke  102 . However, relative to the configuration of  FIG. 6A , the larger diameter outer surface  157  may provide a smaller clearance between tubular extension  140  and insert  134  of receptacle  126 . 
     Referring again collectively to  FIGS. 6A-6C , the interface of retention ring  150  and/or retention ring  152  and latching yoke  160  (e.g., when cable receptacle  126  is slid fully onto tubular extension  140 ), may removeably lock cable receptacle  126  in place. Elastic properties of latching ring  160 , insert  134 , and/or cable receptacle  126  may permit removal of cable receptacle  126  from tubular extension  140  using, for example, a removal tool. 
     In implementations described herein a yoke for a power cable connector may include a spade assembly that includes a bore therethrough and an electrical interface for a receptacle of a power cable. A tube-like structure may be affixed to the yoke and configured to encircle at least a portion of the spade assembly. The tube-like structure may include an entry hole through the tube-like structure to permit insertion of a fastener transversely through the tube-like structure and through the bore to securing the spade assembly to a portion of a second electrical component, such as a spade assembly of a power cable. The tube-like structure may have an outside diameter configured to engage an inside diameter of the receptacle and support the receptacle when the receptacle is connected to the electrical interface. 
     The above-described power cable yoke with tubular extension provides an effective and repeatable means for preventing misalignment and/or relative movement of a yoke and an installed power cable assembly. Misalignment and/or movement may occur, for example, from bending forces caused by a high current momentary surge. This misalignment and/or movement may compromise the weather-resistant barrier provided by the cable receptacle. For example, water may reach the interface between cable receptacle and the taps of the yoke and eventually cause the connecting parts to electrically fail. 
     The foregoing description of exemplary implementations provides illustration and description, but is not intended to be exhaustive or to limit the embodiments described herein to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the embodiments. For example, implementations described herein may also be used in conjunction with other devices, such as high voltage switchgear equipment, including 15 kV, 25 kV, or 35 kV equipment. 
     For example, various features have been mainly described above with respect to electrical connectors, and splicing or yoke-type connectors in particular. In other implementations, other medium/high voltage power components may be configured to include the connection mechanism configurations described above. 
     Although the invention has been described in detail above, it is expressly understood that it will be apparent to persons skilled in the relevant art that the invention may be modified without departing from the spirit of the invention. Various changes of form, design, or arrangement may be made to the invention without departing from the spirit and scope of the invention. Therefore, the above-mentioned description is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined in the following claims. 
     No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.