Abstract:
A transition assembly for interconnecting a hybrid trunk cable and electronic equipment includes: an enclosure having first and second ends, first and second side walls, and a cavity; a hybrid trunk cable comprising first and second sets of pluralities of power conductors and a plurality of optical fibers, wherein the first and second sets of power conductors enter the enclosure at the first end; first and second sets of pluralities of connectors mounted to at least one of the first and second side walls; and an overvoltage protection module (OVP module).

Description:
RELATED APPLICATION 
       [0001]    The present application claims priority from and the benefit of U.S. Provisional Patent Application No. 62/256,318, filed Nov. 17, 2015, the disclosure of which is hereby incorporated herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to power and signal distribution, and more particularly to distribution from hybrid cables. 
       BACKGROUND 
       [0003]    Latest developments in technology for delivering power and data in wireless infrastructure use hybrid cables, wherein the term “hybrid cable” is intended to mean a cable that includes both power conductors and one or more fiber optic cords or cables. An exemplary hybrid cable is the HFF cable, available from CommScope, Inc. (Joliet, Ill.). Unlike RF-based systems, a single hybrid trunk cable can be used to power multiple sectors, thereby eliminating multiple runs of RE cable. However, in order to use a single hybrid trunk cable, at some point the trunk cable must transition to jumper cables or cords. Typically, these are distributed inside an enclosure that transitions the trunk conductor gauge to the jumper conductor gauge and connects the optical fibers in the trunk to the optical fibers in the jumper cables. 
         [0004]    Currently, transitions are achieved by making connections inside the enclosure, requiring it to be opened, cables to be fed/mated to the enclosure, and power and fiber connections to be made, all in the field (e.g., on the top of antenna tower sites near a remote radio unit (RRU)). This practice can create many issues for installers, including time, safety, connection errors (such as loose power connections and/or poor fiber cleaning), and more opportunity for connector damage. 
         [0005]    In addition, at some sites it is desirable to provide overvoltage protection (OVP) for the RRU. OVP is usually supplied via a separate mounted enclosure that is connected to the power conductors of a hybrid cable. Jumper cords are then connected from the mounted enclosure to RRUs. These additional connection add time and expense to the interconnection process. It may be desirable to provide additional configurations for providing OVP at the top of an antenna tower. 
       SUMMARY OF THE INVENTION 
       [0006]    As a first aspect, embodiments of the invention are directed to a transition assembly for interconnecting a hybrid trunk cable and electronic equipment. The transition assembly comprises: an enclosure having first and second ends, first and second side walls, and a cavity; a hybrid trunk cable comprising first and second sets of pluralities of power conductors and a plurality of optical fibers, wherein the first and second sets of power conductors enter the enclosure at the first end; a plurality of connectors mounted to at least one of the first and second side walls; and an overvoltage protection module (OVP module). The OVP module comprises: an overvoltage, unit mounted in the enclosure and configured to create an open electrical circuit when experiencing a voltage higher than a predetermined threshold; a first contact mounted in the enclosure and connected with the first set of power conductors; a second contact mounted in the enclosure in electrical isolation from the first contact, the second, contact connected, with the second set of power conductors; a first OVP conductor connected between the first contact and the overvoltage unit; a second OVP conductor connected between the second contact and the overvoltage unit; a third contact mounted in the enclosure and connected with the connectors; a fourth contact mounted in the enclosure in electrical isolation from the third contact, the fourth contact connected with the connectors; a third OVP conductor connected between the overvoltage unit and the third contact; and a fourth OVP conductor connected between the overvoltage unit and the fourth contact. 
         [0007]    As a second aspect, embodiments of the invention are directed to a transition assembly for interconnecting a hybrid trunk cable and electronic equipment, comprising: an enclosure having first and second ends, first and second side walls, and a cavity; a hybrid trunk cable comprising first and second sets of pluralities of power conductors and a plurality of optical fibers, wherein the first and second sets of power conductors enter the enclosure at the first end; first and second sets of pluralities of connectors, mounted to at least one of the first and second side walls; and an overvoltage protection module (OVP module). The OVP module comprises: an overvoltage unit mounted in the;enclosure and configured to create an open electrical circuit when experiencing a voltage higher than a predetermined threshold; a first contact mounted in the enclosure and connected with the first set of power conductors; a second contact mounted in the enclosure in electrical isolation from the first contact, the second contact connected with the second set of power conductors; a first OVP conductor connected between the first contact and the overvoltage unit; a second OVP conductor connected between the second contact and the overvoltage unit; a third, contact mounted in the mounting frame and connected with the connectors; a fourth contact mounted in the mounting frame in electrical isolation from the third contact, the fourth contact connected with the connectors; a third OVP conductor connected between the overvoltage unit and the third contact; a fourth OVP conductor connected between the overvoltage unit and the fourth contact; a first direct conductor extending between the first and third contacts; and a second direct conductor extending between the second and fourth contacts. 
         [0008]    As a third aspect, embodiments of the invention are directed to a transition assembly for interconnecting a hybrid trunk cable and electronic equipment, comprising: an enclosure having first and second ends, first and second side walls, and a cavity; a hybrid trunk cable comprising first and second sets of pluralities of power conductors and a plurality of optical fibers, wherein the first and second sets of power conductors enter the enclosure at the first end; a plurality of connectors mounted to at least one of the first and second side walls; and an overvoltage protection module (OVP module) comprising: an overvoltage unit mounted in the enclosure and configured to create an open electrical circuit when experiencing a voltage higher than a predetermined threshold; a first contact mounted in the enclosure and connected, with the first set, of power conductors and with the connectors; a second contact mounted in the enclosure in electrical isolation from the first contact, the second contact connected with the second set of power conductors and with the connectors; a first OVP conductor connected between the first contact and the overvoltage unit; a second OVP conductor connected between the second contact and the overvoltage unit; a first direct conductor extending between the first and third contacts; and a second direct conductor extending between the second and fourth contacts. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]      FIG. 1  is a bottom perspective view of a transition assembly according to embodiments of the present invention. 
           [0010]      FIG. 2  is a side perspective view of the transition assembly of  FIG. 1 . 
           [0011]      FIG. 3  is a top perspective view of the transition assembly of  FIG. 1  with the cover removed and a portion of the power conductors removed for clarity. 
           [0012]      FIG. 4  is a top view of the transition assembly of  FIG. 1  with the cover removed. 
           [0013]      FIG. 5  is a top perspective view of an OVP module mounted in the transition assembly of  FIG. 1 . 
           [0014]      FIGS. 6 and 7  are interior and exterior perspective views of hybrid connectors to be used with the transition assembly of  FIG. 1 . 
           [0015]      FIG. 8  is a threaded cable sleeve for the transition assembly of  FIG. 1 . 
           [0016]      FIG. 9  is a top perspective view of the housing of the transition assembly of  FIG. 1 . 
           [0017]      FIG. 10  is a bottom perspective view of the cover of the transition assembly of  FIG. 1 . 
           [0018]      FIG. 11  is a top view of a transition assembly according to alternative embodiments of the invention with the cover removed. 
           [0019]      FIG. 12  is a top perspective view of an OVP module of the transition assembly of  FIG. 11 . 
           [0020]      FIG. 13  is a top perspective view of a stairstep contact of the transition assembly of  FIG. 11 . 
           [0021]      FIG. 14  is a top view of a transition assembly according to further embodiments of the invention. 
           [0022]      FIG. 15  is a perspective view of a stairstep contact of the transition assembly of  FIG. 14 . 
           [0023]      FIG. 16  is a top view of a transition assembly according to still further embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The present invention is described with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments that are pictured and described herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It will also be appreciated that the embodiments disclosed herein can be combined in any way and/or combination to provide many additional embodiments. 
         [0025]    Unless otherwise defined, all technical and scientific terms that are used in this disclosure have the same meaning, as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the below description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this disclosure, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when an element (e.g., a device, circuit, etc.) is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
         [0026]    Referring now to the drawings, a transition assembly, designated broadly at  10 , is shown in  FIGS. 1-10 . The assembly  10  includes a hybrid trunk cable  12 , a transition enclosure  40 , multiple hybrid connectors  20 , and an overprotection (OVP) module  70  (not shown in  FIGS. 1 and 2 ). These components are discussed in greater detail below. 
         [0027]    Referring to  FIGS. 1, 2, 9 and 10 , the transition enclosure  40  has a generally rectangular housing  47  with a floor  41 , side walls  42 , end walls  43 , and a cover  44 , although in other embodiments (such as that shown in  FIG. 16  and discussed below) the housing  40  may take different configurations. The floor includes a ridge  41   a  with slots  41   b  that, can be used for mounting of the assembly  10  (for example, with hose clamps). The side walls  42  include mounting holes  51  for the hybrid connectors  20 , and one end, wall  43  includes a hole  52  through which the hybrid trunk cable  12  is routed into the enclosure. The cover ( FIG. 10 ) has a lip  53  that mates with the upper edges of the side walls  42  and the end walls  43 ; the presence of the cover  44  enables components within the enclosure  40  (such as the OVP unit  200 ) to be replaced in the field. The transition enclosure  40  is typically formed of polymer or polymer composite materials, but may comprise a number of suitable dielectric materials, 
         [0028]    Referring now to  FIGS. 1, 6 and 7 , three hybrid connectors  20  are mounted on each side wall  42  in the mounting holes  51 . The hybrid connectors  20  are configured to receive hybrid jumper rabies/cords with mating connectors. On its exterior sides ( FIG. 6 ), each hybrid connector  20  has four fiber ports  55  and two power contacts  56 . These align with fiber ports  57  and power contacts  58  located on the interior side of the connector  20  ( FIG. 7 ). An exemplary hybrid connector  20  is an LC or multifiber MPO Fiber/Copper connector, available from Amphenol, which meets MIL-DTL-38999 specifications and can withstand severe environmental conditions. 
         [0029]    The hybrid trunk cable  12  has a plurality of power conductors  13  (see  FIGS. 3 and 11 ) and a plurality of optical fibers (see optical fibers  514  in  FIG. 11 ) encased in a jacket  15 . The hybrid trunk cable  12  enters the transition enclosure  40  through the hole  52  in one of the end walls  43 . In the illustrated embodiment, the entry point of the hybrid trunk cable  12  includes a threaded sleeve  45  (see  FIG. 8 ), but other entry components that provide a seal at the entry point, such as cable glands, gaskets, sealing compounds, and the like, may also be employed. The threaded sleeve  45  can be field installed inside the enclosure  40 . Also, if the sleeve  45  is metallic, it can be connected to an armored cable and used as grounding. 
         [0030]    Referring now to  FIGS. 3-5 , the interior cavity  46  of the enclosure  40  hosts an OVP module  70 . The OVP module  70  includes an OVP unit  200  mounted to the floor  41  with two holes at one end and two holes at the opposite end (the holes are not shown in  FIGS. 3 and 4 ). The OVP unit  200 , which is configured to create an open electrical circuit when experiencing a voltage higher than a predetermined threshold, can take a conventional form known to those of skill in this art and need not be described in detail herein. An exemplary unit is the VAL-MS-T1/T2 48/12.5 ST SPD (Surge Protection Device), available from Phoenix Contact. 
         [0031]    Two stairstep entry contacts  82 ,  83  are mounted to the floor  41  between the OVP unit  100  and the end wall  43  through which the hybrid trunk cable  12  enters. Similarly, two stairstep exit contacts  84 ,  85  are mounted to the floor between the OVP unit  209  and the opposite end wall  43 . Each of the stairstep contacts  82 - 85  essentially identical; thus, the discussion below with respect to the stairstep contact  82  is equally applicable to the other stairstep contacts  83 - 85 . It should be noted that the stairstep contacts  82 ,  83  are in electrical isolation from each other, as are the stairstep contacts  84 ,  85 . 
         [0032]    The stairstep contact  82  has a stepped base  86  with two lower surfaces  87 ,  88  and two upper surfaces  89 ,  90  atop respective steps  91 ,  92 . The lower surface  87  shares an edge with an end face  93  with three receptacles  94 . Each of three holes  95  in the lower surface  87  communicates with a corresponding receptacle  94 . A face  96  shares an edge with the upper surface  89  and has three receptacles  97 ; three holes  98  communicate with the receptacles  97 . The lower surface  88  has a hole  99  that communicates with a receptacle  100  in an end face  105  that shares an edge with the upper surface  90 . 
         [0033]    As can be seen in  FIGS. 3 and 4 , the power conductors  13  of the hybrid trunk cable  12  enter the enclosure through the sleeve  45  mounted in the end wall  43  of the transition enclosure  40 . Each of the power conductors  13  is routed to a respective receptacle  94 ,  97  of one of the stairstep contacts  82 ,  83 . Screws are inserted into the holes  95 ,  98  to secure the power conductors  13  in place (an exemplary screw is shown in  FIG. 13  at  409 ). A conductor  102  is routed from the receptacle  99  of the contact  82  to one of the holes  202  in the OVP unit  200 , and another conductor  103  is routed from the receptacle  99  of the contact  83  to the other of the holes  202  in the OVP unit  200 ; the conductors  102 ,  103  are secured in place with screws inserted into the holes  98 . 
         [0034]    At the opposite end of the OVP unit  200 , a conductor  220  is inserted into one of the holes  204  and is routed to the receptacle  100  of the stairstep contact  84 , where it is secured with a screw inserted into the hole  99 . A second conductor  222  is inserted into the other of the holes  204  and is routed to the receptacle  100  of the stairstep contact  85 , where it is secured with another screw inserted into the hole  99 . 
         [0035]    Three power conductors  110  are inserted into the receptacles  97  of each of the contacts  84 ,  85  and three additional power conductors  110  are inserted into the receptacles  94  of each of the contacts  84 ,  85  (only four of the twelve power conductors  110  are shown herein). Screws secure the power conductors  110  into place. Two power conductors  110  are then routed to each of the hybrid connectors  20  to supply power thereto, with one power conductor  110  being routed to each connector  20  from each of the contacts  84 ,  85 . 
         [0036]    It can be seen that power signals travelling on the twelve power conductors  13  reach the stairstep contacts  82 ,  83 , where they are combined into two signals (one each for stairstep contacts  82  and  83 ). As noted above, the stairstep contacts  82 ,  83  are electrically isolated from each other. These two combined signals are routed from their respective contacts  82 ,  83  to the conductors  102 ,  103 , in which they travel to the OVP unit  200 . The signals exit the OVP unit  200  and travel through the conductors  220 ,  222  to the stairstep contacts  84 ,  85  (which, as noted, above, are electrically isolated from each other), where they are separated as they are routed to the power conductors  110  and subsequently to the hybrid connectors  20 . Hybrid jumper cables can be attached to the connectors  20  for subsequent attachment to RRUs or other tower-top equipment. Thus, it can be seen that the same number of electrical power signals that enter the transition enclosure  40  also exit the transition enclosure  40 , but are combined into two signals for routing through the OVP module  70  in order to simplify the overall design. 
         [0037]    In normal operation, the power signals are routed as discussed above. In the event of a voltage surge (for example, caused by a lightning strike), the OVP unit  70  is configured to create an open circuit, with the result that the electronic components (such as the RRU and the antenna) are protected from the voltage surge. 
         [0038]    It will also be understood that the optical fibers of the hybrid cable  12  will be connected with the connectors  20  (as shown by the fibers  514  in  FIG. 11 ). In some embodiments, the optical fibers are “passed through” directly to the connectors  20  (this can be seen in connection with the embodiment discussed below with respect to  FIGS. 11-13 ); in other embodiments, the optical fibers are spliced via conventional means (such as a splice tray) to additional optical fibers that are routed from the splice sites to the connectors  20 . 
         [0039]    Those skilled in this art will appreciate that the transition assembly  10  may take other forms. For example, the transition enclosure  40  may take a different shape. Referring to  FIG. 16 , a transition enclosure  340  has two side walls  342  that angle inwardly to meet a ceiling  343  with the result that the transition enclosure  340  is generally trapezoidal in cross-section. Another embodiment may have two side walls that angle inwardly and merge, such that the transition enclosure is generally triangular in cross-section. Other configurations may be suitable also. Also, the transition enclosure  340  has an integrated nozzle that receives the trunk cable, whereas the sleeve  45  shown in  FIG. 4  is a separate piece that can be sized differently to serve different sizes of trunk cable. 
         [0040]    Further, the entry of the hybrid cable into the transition enclosure may vary. For example, the hybrid cable may be terminated with a connector, and the enclosure may include a mating connector, in which case the cable may be detachable and assembled to the enclosure in the field. In some embodiments, the hybrid cable may be divided into fiber optic and power subunits prior to entering the transition enclosure. Other variations in addition to those discussed above may be suitable fir use herein. 
         [0041]    In addition, the connectors of the transition enclosure  40  may differ from the hybrid connectors shown herein. In some embodiments, the assembly  10  may include separate power and fiber optic connectors. Also, all of the connectors may be located on a single wall of the enclosure (which may be a side or end wall), or in the instance of separate power and fiber optic connectors, the power connectors may be located on one wall and the fiber optic connectors located on another wall. 
         [0042]    Moreover, the stairstep contacts may take a different shape. For example, they may be configured as one long rectangular body with holes. The contacts may be positioned parallel to the long axis, in which case the hybrid cable may be routed installed or from the top with screws. 
         [0043]    In some embodiments, the interior cavity  46  of the transition, housing  40  may be at least partially filled with a potting compound, such as an epoxy, to maintain environmentally sealed conditions. 
         [0044]    Referring now to FIGS,  1143 , an embodiment of a transition assembly, designated broadly at  510 , is shown therein. As can be seen in  FIG. 11 , the transition assembly  510  includes an enclosure  540 , a hybrid trunk cable  512 , and hybrid connectors  520  as are described above. However, the OVP module  570  differs somewhat from the OVP module  70 , as discussed below. 
         [0045]    Referring first to  FIG. 13 , an exemplary stairstep contact  582  is shown there (the other stairstep contacts  583 - 585  are identical). The stairstep contact  582  is similar to the stairstep contacts  82 - 85  described above, but has two receptacles  600  on its end face  605  rather than a single receptacle. As shown in  FIG. 12 , an OVP unit  700  is similar to the OVP unit  200  with the exception that the OVP unit  700  has three small contact holes  721  on one end in addition to the aforementioned single hole. 
         [0046]    Referring now to  FIG. 11 , it can be seen that conductors  513  are routed from the hybrid trunk cable  512  to the stairstep contacts  582  and  583  as discussed above with respect to the transition assembly  10 . In addition, conductors  602 ,  603  are routed from holes in the stairstep contacts  582 ,  583  to the OVP unit  700 . However, an additional conductor  602   a ,  603   a  is routed from each of the stairstep contacts  582 ,  583  directly to a respective stairstep contact  584 ,  585  without passing through the OVP unit  700 . A conductor  610  is routed to each connector  520  from the contact  584  and a second conductor  610  is routed to each connector  520  from the contact  585 . In addition, a conductor  720  is routed from the OVP unit  700  to a ground connection  724  mounted to the end wall  543 , and two smaller conductors  722  are routed from the small contact holes  721  to an alarm (not shown). 
         [0047]    In normal operation, power signals are routed between the stairstep contacts  582 - 585  through the conductors  602 ,  602   a ,  603 ,  603   a . In the event of a voltage surge, however, the electrical path represented by the conductor  720  to the, ground connection  724  represents the path of lowest resistance, and therefore enables the OVP unit  700  to protect the electronics connected to the transition assembly  510 . However, in contrast to the transition assembly  10 , which is disabled from activity in the event of a voltage surge and therefore must be replaced before communications with attached RRUs can be restored, the transition assembly  510  can continue to provide signals to attached equipment (although without OVP capability) until the transition assembly  510  can be replaced with another unit with OVP capability. 
         [0048]    Also, the presence of the conductors  724  can activate the attached alarm, which can signal a technician that the transition assembly  510  should be replaced. 
         [0049]    Referring now to  FIGS. 14 and 15 , another embodiment of a transition assembly, designated broadly at  810 , is shown therein. The transition assembly  810  includes an enclosure  840 , a hybrid trunk cable  812 , and hybrid connectors  820  as are described above. However, the OVP module  870  differs somewhat from the OVP module  70 , as discussed below. As can be seen in  FIG. 14 , the OVP module  870  includes only two stairstep contacts  884 ,  885 , each of which includes an additional “step.” Also, the OVP unit  1000  is similar to the OVP unit  700 , but is oriented  180  differently, such that the smaller contact holes for the alarm conductors  922  face the hybrid trunk cable  812 . As shown in  FIG. 15 , the stairstep contacts  884 ,  885  have three lower surfaces  887 ,  888 ,  889  and two upper surfaces  890 ,  891 , with four faces  892 ,  893 ,  894 ,  895  with receptacles  896  for conductors. 
         [0050]    As can be seen in FIG,  14 , the conductors  813  of the hybrid trunk cable  812  are routed directly to respective stairstep contacts  884 ,  885 . A respective conductor  1020 ,  1022  is routed from each stairstep contact  884 ,  885  to the OVP unit  1000 . A conductor  1023  is routed from the OVP unit  1000  to ground, and two small conductors  1024  are routed from the OVP unit  1000  to an alarm. 
         [0051]    Like the transition assembly  510 , the transition assembly  810  can provide protection against a voltage surge, but can do so with fewer stairstep contacts. 
         [0052]    The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.