Abstract:
Telecommunications carrier equipment in a field cabinet can be replaced so as to allow existing carrier multiplexers to be powered by newer, smaller power supply equipment. Each carrier multiplexer has a plurality of power connections for each of a plurality of power types. The existing set of power supply equipment has a supply connection corresponding to each power connection at each power types. The power inputs of each power type for each carrier multiplexer are bridged together. A replacement set of power supply equipment has a single supply connection corresponding to each power type for each carrier. Each of the bridged power inputs for each carrier multiplexer is connected with the corresponding supply connection on the replacement set of power supply equipment for each power type.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to servicing telecommunications equipment located in the field.  
           [0003]    2. Background Art  
           [0004]    Telecommunications systems are typically designed as a collection of distributed central offices interconnected by high speed trunks. Each central office contains switches for routing calls carried over the trunk lines to individual carrier loops running between the central office and subscriber premises.  
           [0005]    As the number of customers supported by a central office grows, the capacity to directly connect the central office to each customer can be exceeded. One costly solution is to build more central offices. A less expensive solution is to run a small set of cables from the central office to a field cabinet located close to customer premises. The cables terminate at one or more carrier multiplexers. Each carrier multiplexer supports a plurality of carrier loops. Signals on the carrier loops are multiplexed onto the central office cables. Thus, the central office is capable of supporting a greater number of customers.  
           [0006]    A carrier multiplexer which has seen great use in the past is the subscriber loop carrier (SLC) such as, for example, the SLC-96. This device enables up to 96 analog subscriber carrier loops to be served by three central office cables. A typical field cabinet may contain up to five SLC-96 carrier multiplexers. The field cabinet also includes power supply equipment supporting the carrier multiplexers. Typically, up to three carrier multiplexers are supplied by a set of power supply equipment. This equipment includes an AC supply receiving AC current from outside of the cabinet. A rectifier circuit converts line AC to DC, typically −48V, for use by the carrier multiplexers. A ringing voltage circuit converts line AC to ringing AC voltage for driving telephone ringers. A battery back-up system, referred to as a battery tray, provides electrical power in the event of external AC cut-off. Finally, alarm logic monitors conditions within the field cabinet and generates alarms typically received by the central office. Alarms may be based on sensing a variety of conditions including AC supply operation, rectifier operation, ringing voltage operation, battery tray operation, equipment temperature, carrier multiplexer operating status, cabinet door opening, and the like.  
           [0007]    The use of carrier multiplexers in remote field cabinets greatly increase the number of subscriber loops which can be supported by a central office. However, once the field cabinet is filled with equipment, and the maximum number of carrier loops supported by this equipment had been dedicated, local capacity is again exhausted. One solution for expansion is to construct another field cabinet to support increasing demand in the area covered by the full field cabinet. However, constructing a new field cabinet is expensive, typically requiring additional easement rights which may not be available as well as the cost of installing another pedestal and AC power feed. Thus, a less expensive alternative is needed.  
           [0008]    Improvements in technology permit a greater number of carrier multiplexers to be packed into the same cabinet volume. Similarly, improvements in power supply technology reduce the cabinet volume necessary to support each new carrier multiplexer. However, for cost and functionality reasons, an advantage may be gained by continuing to use existing carrier multiplexers such as the SLC-96.  
           [0009]    Thus, a problem arises. Replacing old power supply equipment with newer, smaller power supply equipment creates additional space for more carrier multiplexers. However, output wiring from new power supply equipment is not compatible with older, existing carrier multiplexers. What is needed is to interconnect newer power supply equipment with older carrier multiplexers. This connection scheme should permit a mixture of newer carrier multiplexers and older carrier multiplexers within the same field cabinet. Further, replacing power supply equipment should be done in a manner that disrupts telecommunications services as little as possible.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention permits replacing telecommunications carrier equipment in a field cabinet so as to allow existing carrier multiplexers to be powered by newer, smaller power supply equipment.  
           [0011]    A method of replacing telecommunications carrier equipment in a field cabinet is provided. A first set of power supply equipment supporting at least one carrier multiplexer is removed. Each carrier multiplexer has power connections for each power type. The first set of power supply equipment has a supply connection corresponding to each power connection at each power type. All of the plurality of power inputs of each power type for each carrier multiplexer are bridged together. A second set of power supply equipment has a single supply connection corresponding to each power type for each carrier multiplexer. Each of the bridged power inputs for each carrier multiplexer is connected with the corresponding supply connection for each power type.  
           [0012]    In an embodiment of the present invention, a central office is notified of possible power related alarms prior to removing the first set of power supply equipment.  
           [0013]    In another embodiment of the present invention, at least one new carrier multiplexer is installed. Each new carrier multiplexer has at least one power input corresponding to each of the power types. For each new carrier multiplexer, the at least one power input for each power type is connected with a corresponding power supply connection on the second set of power supply equipment. At least one high-bandwidth cable is connected to the central office side of each new carrier multiplexer. A plurality of carrier loops are connected to the customer premises side of each new carrier multiplexer. The new carrier multiplexer may be a digital carrier system such as, for example, an NEC-ISC-303.  
           [0014]    In still another embodiment of the present invention, the second set of power supply equipment comprises a Lucent CPS-4000.  
           [0015]    In yet another embodiment of the present invention, at least one carrier multiplexer is an SLC-96.  
           [0016]    In a further embodiment of the present invention, the plurality of power types includes −48 VDC and ground return. The plurality of power types may also include positive ringing AC and negative ringing AC.  
           [0017]    A remote terminal cabinet is also provided. The cabinet includes a housing located outside of a telecommunications central office. Equipment in the housing is connected to the central office through high-bandwidth cables. Equipment in the housing is connected to customer premises through carrier loops. Carrier multiplexers are disposed within the housing. Each carrier multiplexer multiplexes at least one of the high bandwidth cables to customer premises carrier loops. At least one of the carrier multiplexers has power connections for each power type. A power supply is also disposed within the housing. The power supply has a power supply connection for each power type on each carrier multiplexer. A bridging connection connects power connections for one power type on a carrier multiplexer with a corresponding power supply connection on the power supply.  
           [0018]    The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a block diagram illustrating carrier multiplexing between a central office and customer premises that may incorporate the present invention;  
         [0020]    [0020]FIG. 2 is a block diagram of a system for supplying power according to the prior art, wherein the power supply has a plurality of connections for each of a plurality of power types on each carrier multiplexer;  
         [0021]    [0021]FIG. 3 is a block diagram of a system for supplying power to carrier multiplexers according to an embodiment of the present invention;  
         [0022]    [0022]FIG. 4 is a schematic diagram of a power connection block from power supply equipment supporting a plurality of power supply connections for each of a plurality of power types; and  
         [0023]    [0023]FIG. 5 is a schematic diagram of a power connection block from power supply equipment according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    With reference to FIG. 1 of the drawings, a block diagram illustrating carrier multiplexing between a central office and customer premises is shown. A telecommunications system, shown generally by  20 , includes central office  22  serving a plurality of customer premises, one of which is indicated by  24 . Telecommunications system  20  may include one or more field cabinets  26  containing telecommunications carrier equipment, shown generally by  28 . Equipment  28  includes one or more carrier multiplexers  30 . Each carrier multiplexer  30  accepts high bandwidth cables  32 , typically three or five T-1 cables, from central office  22  at central office side  34  of carrier multiplexer  30 . Cables  32  may utilize various transmission media including twisted pair conductors, fiber optic cables, and the like. Carrier multiplexer  34  accepts a plurality of carrier loops  36  from customer premises  24  at customer premises side  38  of carrier multiplexer  30 . Each carrier loop  36  may support voice and data transmissions between customer premises  24  and carrier multiplexer  30 . Carrier multiplexer  30  multiplexes carrier loops  36  onto cables  32  using various techniques such as, for example, time division multiplexing. A variety of carrier multiplexer types are available including traditional analog multiplexers such as the SLC-96, digital carrier systems such as the ISC-303 from NEC Eluminant Technologies, Inc. of Herndon, Va., and the like.  
         [0025]    Field cabinet telecommunications carrier equipment  28  also includes power supply equipment  40  providing power to carrier multiplexers  30 . Power supply equipment  40  may include an AC supply accepting line voltage from outside of the field cabinet, one or more rectifiers for converting line voltage to DC, ringing voltage converters for converting line AC to ringing voltage AC, battery trays providing power back-up in case of AC failure, alarm logic for monitoring the status of field cabinet  26 , and the like.  
         [0026]    Referring now to FIG. 2, a block diagram of a system for supplying power according to the prior art is shown. Typical old-style power supply equipment  50  utilizes ferroresonant technology which requires a relatively large amount of space within field cabinet  26 . Each set of power supply equipment  50  supports two to three old-style carrier multiplexers  52 , such as SLC-96 systems. Each carrier multiplexer  52  requires a plurality of power types  54 . In FIG. 2, two power types  54  are illustrated. Power type A, indicated by reference  54   a , might be, for example, −48 VDC. Power type B, indicated by reference  54   b , might be, for example, the return ground for the −48 VDC supply. Each carrier multiplexer  52  has a plurality of power connections  56  for each power type  54 . In FIG. 2, power type  54   a  has connectors  56   a ,  56   b ,  56   c  and power type  54   b  has power connections  56   d ,  56   e ,  56   f.    
         [0027]    Power supply equipment  50  has supply connections  58  corresponding to power connections  56  on each carrier multiplexer  52  supported by power supply equipment  50 . Thus, power supply equipment  50  has supply connection  58  for each power connection  56  of each power type  54  for each carrier multiplexer  52 . In FIG. 2, power supply equipment  50  has supply connection  58   a ,  58   b ,  58   c  of power type  54   a  and supply connection  58   d ,  58   e ,  58   f  of type  54   b . Each supply connection  58   a - 58   f  connects with corresponding power connection  56   a - 56   f  of a first carrier multiplexer  52 . Power supply equipment  50  also has supply connection  58   g,    58   h ,  58   i  of power type  54   a  and supply connection  58   j,    58   k,    58   l  of power type  54   b . Supply connections  58   g - 58   l  connect with corresponding power connections  56   a - 56   f  of a second carrier multiplexer  52 .  
         [0028]    Referring now to FIG. 3, a block diagram of a system for supplying power to carrier multiplexers according to an embodiment of the present invention is shown. Old-style power supply equipment  50  has been replaced with power supply equipment  70  constructed using microelectronic technology. Power supply equipment  70  thus requires less space within field cabinet  26 , allowing more space for additional carrier multiplexer  72 . In addition to being smaller, power supply equipment  70  is more efficient, generates less heat, and requires only one supply connection  74  for each power type  54  on each carrier multiplexer  52 , 72 .  
         [0029]    In order to connect carrier multiplexers  52  to power supply  70 , power connections  56  for each power type  54  on each carrier multiplexer  52  must be joined in bridge  76 . In FIG. 3, bridge  76   a  connects power connections  56   a ,  56   b ,  56   c  of power type  54   a  on first carrier multiplexer  52 . Bridge  76   b  connects power connections  56   d ,  56   e ,  56   f  of power type  54   b  on first carrier multiplexer  52 . Bridge  76   c  connects power connections  56   a ,  56   b ,  56   c  of power type  54   a  on second carrier multiplexer  52 . Bridge  76   d  connects power connections  56   d ,  56   e ,  56   f  of power type  54   b  on second carrier multiplexer  52 . Bridge  76   a  connects to supply connection  74   a , bridge  76   b  connects to supply connection  74   b , bridge  76   c  connects to power connection  74   c , and bridge  76   d  connects to supply connection  74   d  on power supply equipment  70 .  
         [0030]    Typically, new carrier multiplexer  72  has one power connection  78  for each power type  54 . Thus, for power type  54   a , power connection  78   a  directly connects to supply connection  74   e . Also, for power type  54   b , power connection  78   b  connects directly supply connection  74   f  of power supply equipment  70 .  
         [0031]    Referring now to FIG. 4, a schematic diagram of a power connection block from power supply equipment supporting a plurality of power supply connections for each of a plurality of power types is shown. Old-style power supply equipment  50  typically includes an interconnected collection of discrete equipment. AC supply  90  conditions power received from AC power input  92  for use by other power supply equipment  50 . AC supply  90  may include transformers, diodes, capacitors, and the like to condition line voltage and protect power supply equipment  50  from damage due to power surges and spikes.  
         [0032]    Rectifier  94  accepts AC line voltage from AC supply  90  and produces DC voltage for use by carrier multiplexers  52 . Typically, this DC voltage includes −48 VDC and a return ground. However additional voltage levels such as, for example, −24 VDC and ground, are within the spirit and scope of the present invention.  
         [0033]    Battery tray  96  supports a plurality of batteries which are charged with energy received from AC power input  92  and return this energy to power supply equipment  50  if AC power input  92  ceases to be received.  
         [0034]    Ringing voltage  98  converts line voltage from AC supply  90  into an AC ringing voltage for use by carrier multiplexers  52 . Ringing voltages vary, but a typical ringing voltage is 105 VAC at 20 Hz.  
         [0035]    Alarm logic  100  monitors various functions within filed cabinet  26  including power supply equipment  50  and carrier multiplexers  52 . When a measured parameter is outside of predetermined tolerances, an alarm signal is generated. This alarm signal is typically transmitted to central office  22 .  
         [0036]    Various components within power supply equipment  50  are interconnected with power equipment cabling  102 . Components  90 ,  94 ,  96 ,  98 ,  100  and their interconnection  102  vary between applications as is well known in the telecommunications art.  
         [0037]    Power and signal wires are connected to power supply equipment  50  through one or more power harnesses, shown generally by  104 . Connections between wires in harnesses  104  and power components  94 ,  98 ,  100  have been omitted for clarity. Such connections vary between applications as is known in the art. Values for individual wires in harness  104  are shown abbreviated in FIG. 4. Abbreviations and corresponding descriptions are summarized in Table 1.  
                           TABLE 1                                   Abbreviation   Description                           TRAJECTORY   DC Test Pair TIP           TTR   DC Test Pair RING           PA   Power Alarm           PAR   Power Alarm Return           MN1   Minor Alarm           MNR1   Minor Alarm Return           MJ1   Major Alarm           MJR1   Major Alarm Return           FR GRD   Frame Ground           −48 V   −48 VDC           RGRD   Return Ground           PRNG   Positive Ringing AC           NRNG   Negative Ringing AC                      
 
         [0038]    Harness  104  terminates in 50-pin 710 module  106 . Module  106  has twenty-five connection pairs numbered 1-25 left-to-right as shown in FIG. 4. As shown in FIG. 4, the left connector of each pair corresponds with the (1) conductor, also known as the TIP side of a pair. The right connector of each pair is the (2) conductor, also known at the RING side of a pair. Typically, 710 module  106  is a female module. Each carrier multiplexer  52  is connected to a male 710 module, not shown for clarity, with necessary like wiring. When the male and female 710 modules are mated, there is continuity between power supply equipment  50  and carrier multiplexer  52 .  
         [0039]    In the example shown in FIG. 4, thirty-four pairs of solid 22-gauge wire interconnect power supply equipment  50  with module  106 . Pair sets two through five, indicated by  108 , carry alarm signals. Pair set six, indicated by  110 , carry the frame ground. Pair sets numbered seven through eleven and fifteen through eighteen, indicated by  112 , are nine pairs of DC voltage and ground connections. Typically, each voltage wire is separately fused within rectifier  94 . Pairs numbered twelve through fourteen, indicated by  114 , supply ringing voltages.  
         [0040]    Referring now to FIG. 5, a schematic diagram of a power connection block from power supply equipment according to an embodiment of the present invention is shown. Power supply equipment  70  requires less volume within field cabinet  26  than older power supply equipment  50 . This is due, in part, to the use of electronics and modularization in major power supply equipment components. One such component is the CPS4000 available from Lucent Technologies, indicated by reference  120 . CPS4000 represents a family of power modules which may be incorporated in the same device  120 . CPS4000 receives AC power input  92  and generates the necessary DC voltage to supply up to eight carrier multiplexers  52 , 72 . Power supply equipment  70  also includes battery tray  122  to support power supply equipment  70  in the event of loss of AC power input  92 . Alarm cross-connect panel  124  terminates alarms received by power supply equipment  70 . Components  120 ,  122 ,  124  within power supply equipment  70  are interconnected by power equipment cabling  126  as is known in the art.  
         [0041]    Connections to power supply equipment  70  are made through one or more power harnesses, shown generally by  128 . Power harness  128  is terminated at 50-pin 710 module  130 . Module  130  is wired to present the same necessary connections provided by module  106  connected to old power supply equipment  50 . Alarm signals  108  occupy pairs two through five in module  130 . Ringing voltage  114  is supplied by pair  12 . DC voltage and ground  112  still appear at pairs seven through eleven and fifteen through eighteen. However, only one connection of each type  54   a ,  54   b  runs from power supply equipment  70  to module  130  at pair eighteen. The remaining pairs seven through eleven and fifteen through seventeen are connected by bridges  76   a ,  76   b . Up to eight modules  130  can be connected to power supply equipment  70  containing CPS4000 rectifier device  120 .  
         [0042]    A method for replacing power supply equipment  50  with power supply equipment  70  that will create a minimal interruption of services to customer premises  24  will now be described. The order of steps taken in the process may be varied considerably and some of the work may be done ahead of time, away from field cabinet  26 .  
         [0043]    Preferably, central office  22  is notified prior to opening field cabinet  26  as various alarms will invariably be tripped during the replacement process. Batteries and battery tray  96  are removed from power supply equipment  50 . Rectifier  94  may also be removed from cabinet  26  without breaking any connections to create more working space within cabinet  26 . The CPS4000 and new battery trays  122  are placed into cabinet  26 . Cabling  126  connecting battery tray  122  with CPS4000 is installed. AC power input  92  is connected to CPS4000. Each 710 module  106  supporting an existing carrier multiplexer  52  designated to remain within cabinet  26  is individually replaced. A corresponding module  130  is wired. Alarm connections  108  are made between module  130  and alarm cross-connect panel  124  using 24-gauge four-pair inside wire or equivalent.  
         [0044]    A 22-gauge insulated solid copper wires is connected to each connector of pair fourteen in module  130  for ringing voltages  114 . The other ends of the ringing wires can be connected to a ringing wiring harness, such as is available in universal power kit K17006A-V01B from Lucent Technologies. The CPS4000 supports four ringing pairs. If more than four carrier multiplexers  52 , 72  are installed in field cabinet  26 , up to eight ringing pairs can be formed by doubling ringing pair wires on connector pins in connectors between module  130  or carrier multiplexers  72  and CPS4000.  
         [0045]    Bridges  76  are constructed in module  130  using 22-gauge insulated solid copper wire. Bridging connections are made between pins in module  130  as shown in FIG. 5. A −48V wire and a RGRD wire run from module  130  and are spliced into a two-conductor power cable which plugs into CPS4000.  
         [0046]    Once module  130  is completely wired, a new mating male 710 module can be constructed by cutting each wire from the male 710 module connected to module  106  and inserting the cut wire into the mating male 710 module for new female module  130 . No loss of power should be experienced by carrier multiplexer  52  due charge held by capacitors within carrier multiplexer  52 . Once all wires from carrier multiplexer  52  have been transferred, module  130  is capped.  
         [0047]    While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.