Patent Publication Number: US-6663438-B1

Title: Modular cable assemblies

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to armored cable and flexible cord. 
     Armored cable typically has a metal sheath (the armor) enclosing one or more individually insulated conductors, e.g., wires. The metal sheath may be formed of a helically interlocked continuous strip of metal, or a smooth or corrugated continuous metal tube. 
     Armored cable is used in constructing commercial wiring systems to distribute electricity for lighting or convenience power. Typically, a number of segments of armored cable are used in a wiring system, for example, that provides power to a series of lighting fixtures in a ceiling. The segments of armored cable in the wiring system must be connected to each other and also to conductors from the lighting fixtures. These connections conventionally are made on-site by linking the ends of the cable, and also the conductors from the fixtures, using cable connectors, wire nuts, and miscellaneous hardware. 
     Modular armored cable assemblies are known. Such assemblies include a precut segment of armored cable having a modular connector attached to each end. A modular connector generally includes a housing assembly with a port for receiving the end of a segment of armored cable and a metal or plastic housing. A modular connector also typically includes one or more plastic connector inserts containing electrical contacts through which an electrical connection is made between conductors from the armored cable and conductors in a modular connector on another segment of armored cable. Generally, the modular connector at one end of a cable assembly may include a connector insert with female channels or male leads that match the female channels and may also include a modular connector at the other end of the cable assembly of similar construction. 
     Modular cable assemblies can be pre-assembled in the desired lengths, with the appropriate modular connectors, and then transported to the installation site of the wiring system. The armored cable assemblies then can be attached sequentially and connected electrically to the electrical panels and their loads in order to provide the wiring system. 
     SUMMARY OF THE INVENTION 
     The invention relates generally to electrical connectors, e.g. modular connectors for use with armored cable and flexible cord. The modular connectors can also be used, e.g., in a modular cable assembly. 
     In particular, the modular connectors are configured for contact sequencing such that electrical contacts in one portion of a connector connect with electrical contacts in a matching portion of the connector in a predetermined, specified sequence. That is, by staggering the positions of the contacts within the connector portions, the contacts connect together at different times (i.e., not simultaneously) when the connector portions are mated together. 
     In some applications, e.g., alternating current applications that use three-phase power with inductive loads, connectors connect all three phases of the system using one connector pair. In cases where there is an inductive electrical load at high voltages, each one of these three phases can produce a high-power electrical arc. Therefore, disconnecting all three phases at the same time can produce three high-power arcs simultaneously. 
     By sequencing the mating and unmating time for the contacts in the connectors, e.g., by disconnecting two of the three phases before the third phase, the amount of arcing in the first two phases can be minimized or eliminated and the amount of power dissipation from the remaining electrical arc can be minimized. Thus, the risk of electrical arcing is minimized, which reduces the risk of danger to personnel, the risk of fire, and/or the possible degradation to the connector. Moreover, because the amount of electrical arcing that the connector material preferably needs to withstand is reduced, cost-effective materials can be used to produce the connectors. The contact sequencing described herein can also be applied to other connectors used in electrical systems having multiple, e.g., greater than three, phases, or in connectors used in three-phase systems and carrying multiples of the three phases, particularly where electrical arcing can result. 
     Other features and advantages of the invention will be apparent from the description of the preferred embodiments thereof, and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a modular wiring system; 
     FIG. 2 is an exploded view of a modular connector in the wiring system in FIG. 1; 
     FIG. 3 is a perspective view of the housing in the modular connector in FIG. 2, with a fixture adapter; 
     FIG. 4 is an exploded view of the connector insert in the modular connector in FIG. 2, and a male connector insert counterpart; 
     FIG. 5 is a perspective view of the cover in the modular connector in FIG. 2; 
     FIG. 6A is a perspective view of a modular connector, with a phase selector; 
     FIG. 6B is a perspective view of the modular connector in FIG. 6A, with the cover removed; 
     FIG. 7 is a side view of a fixture adapter collar; 
     FIG. 8 is a top view of the stamped metal piece used to form the fixture collar in FIG. 7; 
     FIG. 9 is a perspective view of the modular connector in FIG. 2 attached to a corresponding modular connector; 
     FIG. 10 is a partial, cross-sectional view of an embodiment of male and female connector inserts; 
     FIG. 11 is a partial, cross-sectional view of an embodiment of male and female connector inserts; 
     FIG. 12A is a top view of a conductor terminal and FIG. 12B is a side view of the terminal; 
     FIG. 13 is a plan view of a second wiring system; 
     FIG. 14 is a perspective view of a housing of a modular connector used in the wiring system in FIG. 13; and 
     FIG. 15 is a perspective view of the modular connector including the housing in FIG.  14 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a modular wiring system  10  for providing power to lighting fixtures  12  includes armored lighting cable assemblies or fixture cable assemblies  14 , switch module  16  connected to switch  18 , circuit starter  20 , and armored extender cable assemblies  22 . Each lighting cable assembly  14  includes an armored cable  23  having a female modular connector  24  on one end and a male modular connector  26  on the other end. Conductors passing through modular connector  24  and a fixture adapter collar (discussed below) provide power to the lighting fixtures. 
     Referring to FIGS. 2-9, female modular connector  24  includes housing  28 , connector insert  30 , and cover  32 . 
     Housing  28  includes a port  34  for receiving the armored cable, V-shaped elements  36  for stabilizing and supporting the cable (see also FIG.  14 ), and U-shaped element  38  for preventing the armored cable from penetrating into the housing beyond the U-shaped element. V-shaped elements  36  rest in the grooves in the armor of the cable; each V-shaped element provides two distinct points of contact for the cable. Housing  28  further includes a metal tab  40  extending vertically from the base of the housing, modular protective element  42 , thumb grip  44  with integrated hanger  46 , channels  48  including slots  50 , and, optionally, phase selector switch  51 . Modular connector  24  optionally may include either a fixture adapter collar  29  (see FIGS. 3,  7 , and  8 ) or a phase selector switch  51  (see FIGS.  6 A and  6 B). The phase selector switch allows an installer to select the appropriate electrical circuit and phase during installation of the wiring system. 
     Fixture adapter collar  29  is attached to housing  28  through a port in the base of the housing. Fixture adapter collar  29  includes snap elements  54  and snap elements  56 . The conductors (not shown) that provide power to a lighting fixture  12  pass through the fixture adapter collar. 
     Fixture adapter collar can be manufactured by stamping spring steel to provide stamped piece  64  (see FIG.  8 ). The stamped piece then is converted through multiple forming operations into fixture adapter collar. 
     In use, the end of fixture adapter collar  29  including snap elements  56  and  54  is pushed through the port in the base of housing  28 . Snap elements  56  snap open after they pass through the port to secure the fixture adapter collar  29  in the housing. The end of fixture adapter collar  29  having snap elements  54  can be pushed into an opening in the lighting fixture to secure modular connector  24  to the lighting fixture. Although secured to the lighting fixture, the fixture adapter collar can still be detached if desired from the fixture without undue effort. 
     Phase selector switch  51  includes notches  65  that receive elements  67  when the modular connector is assembled (see FIG.  6 B). Notches  65  and elements  67  prevent the switch housing from rotating and also provide a convenient keying mechanism. 
     Connector insert  30  includes a lower portion  66  and an upper portion  68 . Lower portion  66  includes channels  70  for positioning wires leading from the connector insert to the armored cable and fixture adapter collar  29 ; female channels  72  for receiving male leads  73  in male connector insert  74  from modular connector  26 ; and insert interlock element  76 . Pin contacts (not shown) are included in male connector insert  74 ; socket contacts (not shown) are included in female connector insert  30 . Conductors are welded to the back of the contacts and exit through openings in their back end. Lower portion  66  also includes slot  84  for receiving metal tab  40  from housing  28  during assembly. When modular connector  24  is assembled with contacts and conductors inside, the ground contact engages metal tab  40  to ground the connector. 
     In certain embodiments, the connector contacts are placed at various depths within the connectors to provide contact sequencing, for example, by using electrical contacts of different lengths to effectively stagger their depths with a connector insert. Referring to FIG. 10, male connector insert  74  defines a contact edge  75  (Plane X) and includes five socket contacts  200  having contact ends variously spaced from the contact edge. Central contact  202  has a contact end  204  that is located at contact edge  75 . On both sides of central contact  202  are two contacts  206  and  208  having contact ends  210  and  212 , respectively, spaced from contact edge  75 . In other words, contact ends  210  and  212  are spaced from contact end  204  of central contact  202 . In this particular embodiment, contact ends  210  and  212  are spaced equally from edge  75 . 
     On both outer sides of contacts  206  and  208  are two more contacts  214  and  216  having contact ends  218  and  220 , respectively, spaced from contact edge  75 . As shown in FIG. 10, contact ends  218  and  220  are spaced equally from edge  75 , and the spacing between edge  75  and contact ends  218  and  220  is greater than the spacing between edge  75  and contact ends  210  and  212 . In this embodiment, the connection sequence is not affected by rotational misalignment between the connector inserts because the configurations of the contacts are symmetrical about a central axis bisecting central contact  204 . 
     Female connector insert  30  defines a contact edge  222  (Plane Y) and includes five pin contacts  224  having contact ends variously spaced from the contact edge. Central contact  226  has a contact end  228  that is located at contact edge  222 . On each side of central contact  226  are two contacts  230 ,  232 ,  234  and  236  having contact ends  238  spaced from contact edge  222 . Contact ends  238  are spaced equally from edge  222 . 
     Male connector insert  74  and female connector insert  30  are configured to mate together along a direction of attachment (Arrow Z). As the connector inserts are brought together, the contacts connect together in a specified sequence, depending on the spacings between the contact ends and the contact edges. Here, as the connectors  74  and  30  are inserted together, first central contact  204  connects with central contact  226 . Contacts  206  and  208  then connect with contacts  230  and  232 , respectively. Then, contacts  214  and  216  connect with contacts  234  and  236 , respectively. As the connectors are unmated, the contacts disconnect in the reverse order of their connection sequence. 
     Other configurations for the contacts, both in male connector insert  74  and in female connector insert  30 , are possible to provide connection of the contacts in a specified, predetermined sequence. For example, referring to FIG. 11, in another embodiment, contacts  206  and  214 , which are on one side of central contact  202 , have contact ends that are equally spaced from edge  75 . Contacts  208  and  216 , on the other side of central contact  202 , have contact ends that are equally spaced from edge  75 , but this spacing is different (here, greater) than the spacing between edge  75  and contact ends of contacts  206  and  214 . Thus, when connector insert  74  is brought together with connector insert  30 , contact  202  connects with contact  226  first. Then contacts  206  and  214  connect with contacts  230  and  234 , respectively; and then contacts  208  and  216  connect with contacts  232  and  236 , respectively. 
     Numerous other configurations for the contacts are possible. The spacings between the contact ends and a contact edge can be varied in other combinations that can provide safe and usable sequential contact connection. For example, referring to FIG. 10, the spacing between contacts  206  and  208  and edge  75  can be greater than the spacing between contacts  214  and  216  from edge  75 . The uniformly spaced contacts can be in the male connector insert, and the variously spaced contacts can be in the female connector insert. Connector inserts  74  and  30  can have, for example, two, three, four, six, and greater than six contacts of various spacings from a contact edge, e.g., in other multi-phase power systems. 
     Referring back to FIG. 4, the lower portion of male connector insert  74  includes interlock element  86 . When modular connectors  24  and  26  are connected, interlock element  76  slides under the surface of interlock element  86 . As a result, inserts  30  and  74  cannot readily rock in the plane corresponding to the bottom of the mated inserts. 
     Upper portion  68  includes slot  88 . 
     Connector inserts  30  and  74  also include a keying mechanism that prevents, for example, a 120V lighting assembly from being connected to a 227V lighting assembly. Referring to FIG. 4, lower portion  66  of connector insert  30  includes five adjacent female channels, and an expanded portion of the plastic material  67 , or key, is in four of the adjacent channels to block the entry of male elements without the matching keys. Analogously, lower portion  86  includes five adjacent male elements. The male elements have plastic housings, and the plastic housings of the four male elements have portions of their plastic housing removed to match the key in the female channels. 
     A terminal assembly  142  is positioned in connector insert  30  as shown in FIG.  12 . Terminal assembly  142  includes a copper terminal  144  at the end of conductor  146 . A portion of terminal  144  is flat. During assembly, the end of a conductor from the armored cable can rest on terminal  144  and then be easily ultrasonically welded to it before insertion into the connector insert. During assembly, the insert top is snapped onto the bottom and is incorporated into the housing. 
     Cover  32  includes downwardly extending metal tab  90  and downwardly extending metal tabs  92 . When modular connector  24  is assembled, metal tab  90  is received by slot  88  and engages the grounding contact to provide a second path with which to ground the connector. Also during assembly, metal tabs  92  are received by corresponding slots  50 . The metal tabs  92  then can be formed or crimped in channels  48  from the side of housing  28  to fasten metal cover  32  to housing  28 . Modular connector  24  thus can be assembled without the use of separate fastening elements. 
     Metal cover  32  further includes protective element  94 , on the opposite side from protective element  42  in housing  28 . Referring to FIG. 9, male modular connector  26  includes a protective element  96  in metal cover  98 . Modular connector  26  is attached to modular connector  24  by inserting male leads (not shown) in a connector insert (not shown) in connector  26  into female channels  72  in housing  28 . During this procedure, thumb grip  44  and a corresponding thumb grip on modular connector  26  inhibit thumbs from sliding along the side of the connectors  24  and  26 . Protective element  96  in metal cover  98  is sized and positioned to fit adjacent to protective element  94  in cover  32  when modular connectors  24  and  26  are attached. Similarly, a protective element (not shown) in the base of housing  100  of connector  26  is sized and positioned to fit adjacent to protective element  42  in the base of housing  28  when modular connector  24  and  26  attached. 
     Housing  28  is made from a metal such as a zinc or aluminum alloy. Cover  32  is made from a metal such as steel or aluminum. Connector insert  30  is made from a thermoplastic such as polycarbonate. 
     There are numerous types of modular connectors, and a particular modular connector may include one or more of the various features discussed above. For example, modular connector  26  does not provide power to a lighting fixture, and thus would not include a fixture adapter like fixture adapter collar  29 . However, in addition to the features of modular connector  26  discussed previously, modular connector  26  also includes V-shaped elements for stabilizing and supporting armored cable; a U-shaped element for preventing the armor on the cable from penetrating beyond a certain point in the housing; a metal tab in the base of its housing and another metal tab in the metal cover that can be received in corresponding slots in the connector insert to ground the modular connector; a housing including vertical elements (with slots) like element  48  for receiving metal tabs in the cover to fasten the cover to the housing; and terminal assemblies like terminal assembly  142 . 
     Referring to FIGS. 13-15, an alternative modular lighting system  148  includes a T-type modular connector  150  including housing  152  and metal cover  153 . T-type modular connector  150  includes many of the features discussed above; see, for example, V-shaped element  154  corresponding to V-shaped element  36  and U-shaped element  156  corresponding to U-shaped element  38 . But connector  150  does not include a fixture adapter collar. Instead, power is provided to a lighting fixture through a female connector insert (not shown) that receives the male leads in a connector insert of another modular connector  152  that ultimately connects to an armored cable or flexible cord that provides power to the lighting fixture. 
     Referring to FIG. 1, modular wiring system  10  includes a plurality of lighting cable assemblies  14  and extender cable assemblies  22 . The lighting cable assemblies and extender cable assemblies used in modular wiring system  10  can be provided as a set. During installation of the modular wiring system, lighting cable assemblies and extender cable assemblies can be connected by attaching mating modular connectors on the ends of the assemblies. 
     The armored cable used in the wiring system can be precoded with visual indicia to indicate that particular cable assemblies should be used together. The visual indicia may be, for example, a color pattern precoded on the surface of each cable, as described, for example, in U.S. Pat. No. 5,468,914, which is incorporated herein by reference. Other visual indicia may be, for example, the color of the plastic connector insert. During installation of the wiring system, an installer can easily identify the cable assemblies designed for use with the wiring system because the relevant assemblies will be precoded with the same color pattern. Similarly, a person inspecting an installed modular wiring system, or otherwise tracking the cable assemblies used in the system, can identify the cable assemblies in the wiring system through the precoded color patterns on the cable and/or of the connector insert, and as a result, distinguish the cable assemblies for different wiring systems in the same area. 
     Other embodiments are within the claims.