Abstract:
A high power electrical connector includes a plug and receptacle for use in a power transmission system. The plug includes a wire conductor attached to a mounting end and a circular contacting portion extending from a second end. The plug is configured to mate with a receptacle connector having a sleeve for engaging the circular extension and a mounting end for connection to a conductive wire. A contacting ring made from a braid provides a low resistance interface between the plug and receptacle minimizing the potential for heat buildup across the interface and minimizing electrical failure.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 62/037,353, filed Aug. 14, 2014 which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The disclosure relates to field of Power Connectors. 
       DESCRIPTION OF RELATED ART 
       [0003]    The disclosure generally relates to an electrical terminal contact and, more specifically, to a high power electrical terminal. These types of terminals are used for power distribution and transmission typically found in wind turbines and other high power applications. In these applications, the connection between the conductor and the terminal is done manually on site by highly trained personnel with hydraulic specialized crimping tools. The connectors are permanently deformed onto the cables. This process is slow, requires highly trained personnel and needs certification. 
         [0004]    Typically, these type of plug and play high power connectors rely on a terminal structure that includes multi-contact beams, (in the order of tens), in an array. Generally these terminals are cylindrical in shape and include contact beams that are formed inwardly around the interior of the terminal creating a series of single contact points along the periphery of the interface between each beam and a mating terminal pin. Such designs are known to fail due to a cumulative current loading effect. When one point of contact fails, the current load is transferred to the next contact which fails with the extra load until finally thermal runaway occurs and complete failure of the connector occurs. 
       BRIEF SUMMARY 
       [0005]    A connector system is provided that includes a plug connector and a receptacle connector. The connector system is used in high power applications such as power distribution systems including windmill and other power distribution system requiring conductive power lines. The connector system includes a plug having a conductive body with a mounting end and a connecting end. The mounting end is configured for connection to a conductive wire or power transmission line, by crimping the wire to the conductive body. The connecting end is adapted to be connected to a corresponding terminal of the mating connector. The contacting portion includes a round or cylindrical extension for engaging a sleeve portion of the mating connector. The mating connector also includes a mounting end connected to a conductive wire or power transmission line. 
         [0006]    The connector system includes a conductive layer positioned between the mating interface of the plug and receptacle connector. The conductive layer includes a contacting ring made from a braid. The braid includes a plurality of individual conductive fibers for creating multiple contact points along the interface. In high current applications, due to resistance, heat buildup can be a potential problem for conductivity. With fewer contact points, the heat buildup can be localized, causing individual contact points to fail which in turn shifts to the next point. In this situation, failure will continue from the first failure point to the second and so forth, until the entire connection fails. In such instances, one can appreciate a high power connector having a novel contacting interface that provides a low resistance contact path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The disclosure is illustrated by way of example, and not limited, in the accompanying figures in which like reference numerals indicate similar elements and in which: 
           [0008]      FIG. 1  is a perspective view of the connector assembly according o the disclosure; 
           [0009]      FIG. 2  is an exploded view of the connector assembly according to  FIG. 1 ; 
           [0010]      FIG. 3  is an alternative exploded view of the connector assembly according to  FIG. 1 ; 
           [0011]      FIG. 4  is a detailed view of the mating end of the plug connector; 
           [0012]      FIG. 5  is a detailed view of the mating end of the receptacle connector; 
           [0013]      FIG. 6  is an exploded view of the mating end of the plug connector according to  FIG. 4 ; 
           [0014]      FIG. 7  is an exploded view of the mating end of the receptacle connector according to  FIG. 5 ; 
           [0015]      FIG. 8  is a sectional view of the mating end of the plug connector according to  FIG. 4 ; 
           [0016]      FIG. 9  is a sectional view of the mating end of the receptacle connector according to  FIG. 5 ; 
           [0017]      FIG. 10  is a perspective view of the contacting ring; 
           [0018]      FIG. 11  is a perspective view of the collar; 
           [0019]      FIG. 12  is a sectional view of the connector assembly according to  FIG. 1 ; 
           [0020]      FIG. 13  is a detail view of the connector assembly according to  FIG. 12 ; 
           [0021]      FIG. 14  is a schematic representing current flow and resistance of the connector assembly according to  FIG. 1 ; 
           [0022]      FIG. 15  is a schematic of the current flow through the contacting ring; 
           [0023]      FIG. 16  is an electrical model of the contacting ring; 
           [0024]      FIG. 17  is another schematic model of the contacting ring; 
           [0025]      FIG. 18  is a further schematic model of the contacting ring; 
           [0026]      FIG. 19  is a detailed view of the braid of the contacting ring of the connector assembly according to  FIG. 1 ; 
           [0027]      FIG. 20  is a detailed view of the braid of the contacting ring; 
           [0028]      FIG. 21  is a resistance model of the braid of the contacting ring; 
           [0029]      FIG. 22  is an overall electrical resistance schematic of the connector and the contacting ring interface; 
           [0030]      FIG. 23  is an electrical resistance schematic of the braid portion of the overall connector interface according to  FIG. 22 ; AND 
           [0031]      FIG. 24  is a perspective view of the prior art. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    As described below, detailed embodiments of the disclosure are presented herein; however, and it is to be understood that the disclosed embodiment is merely exemplary of the disclosure, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure. It is to be understood that the disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms. 
         [0033]    As best shown in  FIGS. 1-3 , the connector system  100  includes a first connector or receptacle connector  60  and a second connector or plug connector  10  adapted to be mated together in electrical engagement along a direction A. As shown in  FIGS. 5, 7 and 9  the receptacle connector  60  includes a conductive body  80  made from an electrically conductive material usually copper or a copper based alloy. In certain power line transmission applications aluminum may also be used as the conductive element. A mounting end  62  is disposed at one end of the body  80  and a connection end  64  is disposed at the other end of the body  80 . A conductive wire  70  having an insulative jacket and an exposed conductive portion  72  is secured to the mounting end  62  of the body  80  of the receptacle connector  60 . In the embodiment shown, the conductive portion  72  is inserted into the mounting portion  62  and the mounting portion  62  is crimped  74  to secure the conductive portion  72  to the body  80 . Other embodiments include attachment methods such as welding or soldering. 
         [0034]    The connection end  64  of the body  80  is constructed in the form of a sleeve  82  having an opening  84  and a pair of slots  86  formed therein. The interior of the sleeve includes a pair of projections  88  formed on the interior surface of the opening  84  of the sleeve  82  and extends around the circular periphery of the opening  84 . In the embodiment shown, the projections  88  are shown as circular, but other shapes are contemplated. The slots  86  formed in the side of the sleeve  82  create flexibility in the sleeve  82  allowing for deflection and expansion of the sleeve  82  upon insertion of the mating connector. A clamp  90  is disposed on the exterior portion of the sleeve  82  and placed over the slots  86 . The clamp  90  limits the deflection and expansion of the sleeve  82  proving overstress protection and increasing normal force when the connectors are mated together. In the present embodiment, the clamp is made from a higher tensile strength material such as stainless steel, but alternative materials can be appreciated that constrain the sleeve  82  from expanding. 
         [0035]    As illustrated in  FIGS. 4, 6 and 8 , the second connector or plug connector is shown having a body  20  including a mounting end  12  extending from one end of the body  20  and a connection end  14  extending from the other end of the body  20 . A conductive wire  30  having an insulative jacket and an exposed conductive portion  32  is secured to the mounting end  12  of the body  20  of the plug connector  10 . In the embodiment shown, the conductive portion  32  is inserted into the mounting portion  12  and the mounting portion  12  is crimped  34  to secure the conductive portion  32  to the body  20 . Other embodiments include attachment methods such as welding or soldering. 
         [0036]    The plug connector  10  includes a body  20  with a connection end  14  having a circular portion  24  extending from the body  20  along direction A. Although the extension  24  in the embodiment is shown as being circular, other cross-sections are contemplated, such as square, hexagonal and so forth. The extension  24  includes a rounded tip  28  for providing a lead-in when the plug connector  10  is mated with the receptacle connector  60 . A contacting ring  40  conforming to the shape of the extension  24 , in this embodiment, which is circular, is disposed on the extension  24  and a collar  50  is placed over the extension  24  and retains the contacting ring  50  on the extension  24 . 
         [0037]    The contacting ring  40 , as best depicted in  FIG. 10  is made from individual conductive fibers  42  woven into a braid  44 , in this embodiment the braid would be a silver plated copper braid and is produced by weaving multiple single strands together into a meshed pattern. In the embodiment shown, the individual conductive fibers are shown to be copper with silver plating, alternative embodiments can include other copper based alloys or conductive materials with other highly conductive plating such as tin or gold. The braids conform to Mil Spec QQB575 or A-A-59569 and are supplied in tubular form. As best shown in  FIG. 11  the collar  50  is formed into the same shape as the extension and is disposed on the extension  24 . The collar  50  is formed from a metallic material but can also be formed from an insulative material. The collar includes a mounting end  56  and a nose end  58 . 
         [0038]    Once the contacting ring  40  has been positioned on the extension  24  the collar  50  is placed over the extension  24  and translated toward the contacting ring  40 . The mounting end  56  of the collar  50  engages the leading edge of the braid  44  of the contacting ring  40  and is crimped or compressed inward, clamping the contacting ring  40  in place. To aid in the assembly, a recess  26  is formed in the extension  24  creating a pocket  26  for the collar  50  to reside. The pocket  26  further locates the collar  50  and the contacting ring  40  in place on the extension  24 . This is established during the assembly of the contacting ring  40  and the collar  50  by creating tactile feedback, that is, as the collar  50  is advanced toward the contacting ring  40 , the collar  50  is essentially pushed on to the extension  24  and snaps into the pocket  26  as the mounting end  56  of the collar  50  clamps down on the confronting edge of the contacting ring  40 . The collar  50  can be further compressed to finally lock down the collar  50  on the extension  24 . Additionally, the collar  50  includes a plurality of spaced apart ramps  54  formed on the exterior surface of the collar  50  and these ramps  54  include tapered edges  55 ,  55 ′ to further guide the extension  24  of the plug  10  into the sleeve  82  of the receptacle  60  during mating. 
         [0039]    The mated assembly is illustrated in  FIGS. 12 and 13 . The plug connector  10  is inserted into the sleeve  82  of the receptacle  90  with the tip  28  aligned with the opening  84 . As the plug  60  is further inserted, the tip  28  guides the plug  10  and pre-aligns the plug  60  in the axial direction A. Upon further insertion, the ramps  54  provide a finer degree of alignment by the tapered edges  55 ,  55 ′ contacting the internal surface of the sleeve  82  and further aligning the extension  24  of the plug  10  with the opening  84  of the sleeve  82 . Once aligned, further insertion of the extension  24  initiates electrical contact between the contacting ring  40  positioned on the extension  24  with the connection end  64  of the sleeve  82 . 
         [0040]    As best illustrated in FIG,  13 , upon complete mating of the plug  10  to the receptacle  60 , electrical contact between the connectors is made through the contacting ring  40 . As shown, the projections  88  formed on the sleeve  82  are disposed directly on the braid  44  of the contacting ring  40 . Due to the biasing effects and the resiliency of the sleeve  82  combined with the added stiffening of the clamp  90 , the projections  88  protrude into the braid  42 . The construction of the braid  44  permits the individual conductive fibers  42  to shift and allows the fibers  42  to conform to the shape of the projections  88  that are in engagement with the braid  44 . In this instance, the braid essentially surrounds the projections  88 . Once mated, the current passes from the cable  70  through the female socket  80  and sleeve  82  and is evenly distributed across the many points of contact created by the braid  44  and contact between receptacle connector  60  and the extension  24  of the plug connector  10 . 
         [0041]    In an alternative embodiment (not shown), the extension of the plug connector may include a step portion, that is, the extension will have an additional portion that has a smaller diameter. In this embodiment, the connector assembly will include two electrical interfaces that utilize a contacting ring. Each contacting ring will be size appropriately for each stepped portion of the extension. The receptacle connector includes a stepped sleeve that is matched with the corresponding stepped portion of the extension. In this embodiment, there is a second electrical interface that can divide the current passing through the connector system even further. The process of splitting the current over hundreds of points of contact reduces Joule heating of the connector. The braid interface length also minimizes the Joule heating process. The braid length is less than  1 mm. For example a 1000 Amp load can be split into more manageable loads of  5 A across the braid interface. A section through the braid interface is depicted in  FIGS. 13 and 15 . 
         [0042]    As shown in  FIG. 24  Louvertac bands  140  are commonly used in current designs to split the current across high power interfaces. The male crimp pin  110  includes one or more recesses to accept the Lourvertac bands  140  which can be Cu Zn Ni Ag &amp; Sn plated. For example, a Louvertac male terminal (LAIBS Type) 0.15 mm BeCu can be bought in 3 feet lengths minimum Ag over Ni plated; rated 1100 A/band for ID 36.8 mm female terminal  160  and rated 900 A/band for ID 30 mm female terminal with an option to reduce the diameter by adding extra bands. The female crimp terminal  160  can be Cu Zn Ni Ag &amp; Sn plated. 
         [0043]    The design of the embodiment shown improves upon Louvertac bands  140  by providing a lower Resistance (bulk braid) which reduces the overall resistance.  FIGS. 12 and 13  show circumferential points of contact CPC and also the minimum length for current path CP. As shown in  FIG. 14 , an electrical resistance model is represented by Resistance (overall)=Resistance (bulk cable  1 )+Resistance (permanent connection  1 )+Resistance (bulk terminal  1 )+Resistance (contact)+Resistance (bulk braid)+Resistance (bulk terminal  2 )+Resistance (permanent connection  2 )+Resistance (bulk cable  2 ). 
         [0044]    If it is assumed that current travels from the center of the circular cross section through the strands and into the outer sleeve, then the distance it must travel through the braid strands is very small as shown in  FIG. 19 . Pouillets Law defines the Resistance, R, as the material resistivity, p, multiplied by the distance of current travel, L, divided by the Cross sectional area, A, normal to the direction of current travel, R=pL/A. So, if L is small, then the Resistance will also be small and this is one of the reasons the braid works so well.  FIGS. 15-18  show current path through the system, while  FIG. 21  shows current path resistance. The schematic shown in  FIGS. 22 and 23  provides a general description of the typical resistance arrangement that can be expected using the braid interface. Another advantage of the system is that it creates multiple contact high points in an arrayed pattern that is definable and predictable which is an advantage to the designer. 
         [0045]    Other factors with this electrical interface that must be considered are increasing the braid pitch reduces the quantity of parallel paths for current flow which increases the electrical resistance and resultant Joule heating. The reduction in strand quantity increases the thermal resistance of the connector. The combined thereto-electric effect increases the temperature of the braid interface. Increasing the contact force reduces the interface electrical resistance by increasing the contact area available to the braid and terminals. This reduction in resistance reduces the Joule heating of the device and overall temperature rise of the interface. The connector design should minimize Joule heating by having a copper braid material of maximum strand diameter, tightly packed strand-to-strand pitch, have a plating surface coating with high thermal and electrical conductivity-to-hardness ratio, (silver is optimum for this situation), and as high a contact force as possible, taking account of braid damage, applied to each strand. 
         [0046]    The above description illustrates a connector assembly system for a wire to wire connection system. The system is shown as a single wire conductor to a single wire conductor with a connection element in the form of a pin and socket. The pin and socket are exposed and the conductive body portions of the plug and socket can be accessed without any insulative barrier. In other embodiments utilizing the above described high power connection system, insulative housing are incorporated. 
         [0047]    In general, the connector system includes a pair of cooperating housings molded from an insulative material. The housings include a cavity formed through the housing that retains respective ones of the plug connector or the receptacle connector and include an interface for joining the housings together and providing a pass through opening so the plug and receptacle can be mated providing the electrical connection. The housings may also include a locking feature disposed across the interface providing a positive connection between the housing that prevents separation of the connectors in normal operation. The housings are generally molded from plastic and are rigid by nature; other housings made from elastomeric materials such as rubber can also be appreciated. These materials provide the necessary insulative barrier but also allow for a certain degree of flexible. In large scale connector systems this can provide additional strain relief and ease in handling. 
         [0048]    It will be understood that there are numerous modifications of the illustrated embodiments described above which will be readily apparent to one skilled in the art, such as many variations and modifications of the compression connector assembly and/or its components including combinations of features disclosed herein that are individually disclosed or claimed herein, explicitly including additional combinations of such features, or alternatively other types of contact array connectors. Also, there are many possible variations in the materials and configurations.