Abstract:
A method of installing a power distribution system in a facility includes acts of: obtaining a power distribution unit including at least one rack mounted power distribution unit, the power distribution unit including an electrical connection having an electrical bus configured to directly connect to a riser of a power busway; installing the power busway from a terminus located at the output of the UPS to the electrical connection at the power distribution unit; and directly connecting the power busway to the output of the UPS with a busbar-to-busbar connection between the output of the UPS and the terminus of the busway.

Description:
BACKGROUND OF INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The invention generally concerns power distribution systems, and in particular, power distribution systems including a UPS. 
         [0003]    2. Discussion of Related Art 
         [0004]    The use of power busway traditionally involves an enclosure which houses multiple electrical conductors in the form of bus. The busway is generally mounted above the electrical load being supplied, for example, secured to the ceiling or other overhead structure. Cable connections are generally employed to complete the connection from the busway to the load. Cable connections are also employed to connect the source of power to the busway. The cable connections to the load are typically made at a tap box. 
         [0005]    A disadvantage of cable connections is that such connections often require a custom installation of electrical conduit between the busway and the source of power and sometimes between the busway and the load. Each of these connections therefore involves custom conduit bending and installation and the custom installation of cables within the conduit, with all of the preceding done in the field. As a result of the required field work, specialized tools and equipment are required. Further, a considerable amount of scrap material, metal shavings and the like may be misplaced or left behind upon completion of the installation. 
       SUMMARY OF INVENTION 
       [0006]    It would therefore be advantageous to provide a power distribution system including a UPS where at least some of the power connections including the power connection from the UPS to a busway are made via a direct connection without the use of cable. In particular, it is advantageous to provide the preceding where the connections are completed on a busbar-to-busbar basis, for example, without the use of cable. The preceding approach helps eliminate custom field installation work that adds cost and complexity. 
         [0007]    In one aspect an uninterruptible power supply (UPS), includes a first input coupled to a source of AC power; first power converter circuitry coupled to the first input, where the first power converter circuitry includes a first plurality of power switches employed to draw current in a controlled manner from the source of AC power, and a first output. According to one embodiment, the UPS also includes second power converter circuitry including a second input coupled to the first output, and a second output, where the second power converter circuitry includes a second to plurality of power switches employed to draw DC current in a controlled manner and to provide AC power at the second output. According to a further embodiment, the UPS includes an electrical enclosure housing each of the first power converter circuitry and the second power converter circuitry where the electrical enclosure includes an electrical connection coupled to the second output and configured for direct attachment to a riser of a power busway. 
         [0008]    In another aspect, an electrical power system includes a power busway including a first terminus, at least one second terminus, and a first busway riser included in the power busway at the first terminus. According to one embodiment, the power system also includes an uninterruptible power supply (UPS) including an input, an output, power conversion circuitry configured to receive AC power, convert the AC power to DC power, and convert the DC power to AC power provided at the output, and an electrical enclosure housing the power converter circuitry and including an electrical connection coupled to the output and configured for a direct attachment to the first busway riser. According to a further embodiment, the electrical power system includes at least one power distribution unit configured for direct attachment to a second busway riser included in the power busway at the at least one second terminus. 
         [0009]    In still another aspect, a method of installing a power distribution system in a facility includes acts of: obtaining a power distribution unit including at least one rack mounted power distribution unit, the power distribution unit including an electrical connection having an electrical bus configured to directly connect to a riser of a power busway; installing the power busway from a terminus located at the output of the UPS to the electrical connection at the power distribution unit; and directly connecting the power busway to the output of the UPS with a busbar-to-busbar connection between the output of the UPS and the terminus of the busway. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    The accompanying drawings, are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various to figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
           [0011]      FIG. 1  illustrates a block diagram of a power distribution system; 
           [0012]      FIG. 2  illustrates a power distribution system according to a further embodiment; 
           [0013]      FIG. 3  illustrates a busway-to-UPS connection in accordance with one embodiment; 
           [0014]      FIG. 4  illustrates an electrical connection in accordance with one embodiment; and 
           [0015]      FIG. 5  illustrates a busway termination in accordance with one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing”, “involving”, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
         [0017]    Where power distribution systems are installed to supply information technology load (IT) it is preferred to reduce or eliminate power cabling that was formerly installed beneath such equipment under raised floors. The installation of busways to supply IT equipment provides for a flexible and scalable approach that connects power distributions units (power panels) to the source of electrical power while avoiding the installation of power conductors beneath raised floors.  FIG. 1  illustrates a power distribution system  8  in accordance with an embodiment in which a UPS is directly connected to one or more power distribution units via a power busway. The power distribution system  8  includes a source of AC power  11 . The power distribution system  8  also includes a UPS  10 , a plurality of power distribution units  12  and a power busway  14 . In the illustrated embodiment, the UPS  10  and the to power distribution units  12  are connected via the power busway  14 . Further, in the illustrated embodiment, the UPS  10  includes one or more electrical enclosures  16  that house power converter circuitry, one or more electrical enclosures  18  that house a static switch and/or a maintenance by-pass switch, and an enclosure  20  that houses an electrical connection. The UPS  10  also includes an input  9  and an output  33 . According to some embodiments, the input  9  is connected to the source of AC power  11  and the output  33  is connected to the power busway  14 , for example, at the electrical connection. 
         [0018]    According to one embodiment, the UPS  10  includes first power converter circuitry  13  including an input  15  and an output  17 , second power converter circuitry  19  including an input  21  and an output  23 , and a DC link  31  which is connected between the output  17  and input  21 . In some embodiments, the output  23  of the second power converter and the output  33  of the UPS can be the same point electrically. However, according to other embodiments additional circuitry is included between the output  23  of the second power converter circuitry and the output  33  of the UPS  10 . According to the illustrated embodiment, the UPS  10  can also include either or both of a solid state switch  27  and a maintenance bypass switch  29 . As illustrated, each of the solid state switch  27  and maintenance bypass  29  are located in the second electrical enclosure  18 . However, either or both of the solid state switch  27  and the maintenance bypass  29  may be located remote from the UPS  10 , i.e., located remote from the second electrical enclosure  18 . Further, where one or both of the solid state switch  27  and the maintenance bypass  29  are physically located within the UPS  10 , the locations of these devices in the enclosure may vary from that illustrated. 
         [0019]    In some embodiments, the system  8  includes one or more DC power sources, for example, batteries  25 . In various embodiments, one or more DC sources such as the batteries  25  may be connected to the DC link  31 . Further, the DC source may be located within the UPS  10  while in other embodiments the DC source (batteries or another type of DC source) may be located remote from the UPS  10 . Other types of DC sources used alone or in combination with the batteries  25  may include extended runtime DC sources, for example, rotary generators, fuel cells, solar power, etc. In some embodiments, a first source of DC power is connected to the DC link  31  while a second source of DC power is connected to the first power converter circuitry  13 , for example, at an additional input to the first power converter circuitry  13 . According to one embodiment, the first source of DC power is an extended runtime source and the second source of DC power includes the batteries  25 . 
         [0020]    According to some embodiments, the first power converter circuitry  13  includes a plurality of solid state power switches that are employed to draw current in a controlled manner from the source of AC power. In a further embodiment, the second power converter circuitry  19  includes a second plurality of solid state switches which are employed to draw DC current in a controlled manner to provide AC power at the output  23 . Accordingly, the specific configuration of the power converter circuitry included in the enclosure  16  can vary depending on the type of UPS employed. For example, the UPS can include an on-line UPS configuration. In addition, embodiments may be employed in a wide variety of applications including those employing a line-interactive UPS design, delta conversion UPSs, flywheel UPSs, motor-generator/battery UPSs and engine-coupled UPSs. 
         [0021]    Where the second power converter circuitry draws DC current, it can do so by drawing the DC current provided at the output of the first power converter circuitry. Further, although a single electrical enclosure  16  is illustrated as housing each of the first power converter circuitry  13  and the second power converter circuitry  19 , the electrical enclosure  16  can include a plurality of enclosures where, for example, a first enclosure houses the first power converter circuitry  13  and a second adjacent enclosure houses the second power converter circuitry  19 . Additional configurations are contemplated including integral batteries included in the UPS  10  and/or remote batteries or other sources of DC power included in the UPS  10  but located remote from the enclosures  16 ,  18 , and  20 , as described above. 
         [0022]    Accordingly, the relative locations of the various components and/or sections of the UPS may differ from that illustrated in  FIG. 1  and embodiments are intended to reach a variety of UPS configurations that are possible. For example, in one embodiment, a UPS includes a first plurality of close-coupled electrical equipment racks that provide the first enclosure  16  and a second plurality of close-coupled to electrical equipment racks that together provide the electrical enclosure  18 . The preceding may also be true for the electrical enclosure  20  because it too may also include either one or a plurality of close-coupled electrical enclosures. For example, a first phase conductor of the power busway  14  can be connected to a first phase of the UPS output in a first electrical enclosure, a second phase of the power busway  14  can be connected to a second phase of the UPS output in a second electrical enclosure, etc. 
         [0023]    In addition, in various embodiments, further changes to the physical arrangement of the electrical enclosures which house the respective system elements of the UPS  10  may be provided relative to those illustrated in  FIG. 1 . For example, the solid state switch  27  may be located in an enclosure that is centrally located within a plurality of close-coupled electrical equipment racks. For example, centrally located within a plurality of close-coupled electrical equipment racks that include the electrical equipment enclosure  16  and the electrical equipment enclosure  20 . The preceding configuration may be employed, for example, where the UPS includes a plurality of first power converter circuitry  13 , i.e. two AC-to-DC power converters operating in parallel. In this configuration, the UPS can include a first electrical enclosure housing a first of the two AC-to-DC power converters and a second electrical enclosure housing a second of the two AC-to-DC power converters. According to this embodiment, the first and second electrical enclosures are close coupled at opposite ends of a centrally located electrical enclosure  18  which houses the solid state switch  27 . Similarly, the UPS can include a plurality of second power converter circuitry, i.e., a plurality of DC-to-AC converters operating in parallel. Further, as indicated above, the maintenance bypass  29  may be remotely located from the UPS  10 . 
         [0024]    In the illustrated embodiment, the power distribution units  12  each include one or a plurality of electrical enclosures (or cabinets) including a remote power panel  22  and one or more equipment racks  24 A- 24 E. In accordance with one embodiment, the remote power panel  22  includes a plurality of branch circuit modules. Such an approach is illustrated and described in detail in U.S. Pat. Nos. 7,606,014 and 7,619,868. Each of these U.S. patents which are commonly assigned to American Power Conversion Corp., are hereby incorporated by reference in their entirety. In to one embodiment, each of the branch circuit modules receives power within the remote power panel  22  and distributes the power via a cable connection. Further, the branch circuit modules can include one or more overcurrent protection devices. Accordingly, the branch circuit module can include one or more multi-pole or single pole circuit breakers. 
         [0025]    In the illustrated embodiment, each of the equipment racks includes a power strip  26  that includes a plurality of receptacle outlets. Further, the system can include one or a plurality of power cables  28  that may include a first power cable  30  and a second power cable  32  connected together at a coupling (or connector)  34 . According to this embodiment, each power cable  28  connects one or more of the power strips  26 , respectively, to the remote power panel  22 . According to another embodiment, a continuous power cable that does not include the coupling  34  can connect the branch circuit module of the remote power panel  22  to the equipment rack  24  and power strip  26 . 
         [0026]    In addition, the equipment racks can include equipment that is connected to the power strip  26  (for example, plugged into). In one embodiment, one or more of the equipment racks include one or a plurality of servers and/or other IT equipment which is supplied power from the power strip  26 . According to other embodiments, power strips  26  are not employed. Instead, equipment located in the equipment racks  24 A- 24 B can be connected to branch circuit modules located in the remote power panels  22  by direct connection to the power cable. The preceding approach may be employed, for example, where the power cable  28  includes an integral connector at the load-end of the cable. 
         [0027]    The system  8  can also include one or more tap boxes  36 . According to one embodiment, the tap boxes  36  are employed to connect the power busway  14  to the power distribution unit  12 . As illustrated, where a plurality of power distribution units  12  are connected to the power busway  14 , the system can include separate tap box  36 A,  36 B for each of the respective power distribution units  12 . Accordingly, in some embodiments, the tap box  36  includes overcurrent protection and short circuit protection for the power distribution unit  12  to which it is connected. According to the illustrated embodiment, the power busway  14  can include one or more bus taps  38  where the bus taps include power bus that is connected to the power busway  14  at a tap box  36  and to a bus connection in the remote power panel  22 . In accordance with one embodiment, the bus tap is connected via a busbar-to-busbar connection at each of the tap box  36  and the remote power panel  22 . The resulting connections can provide the system  8  with a completely cable-free circuit that couples the output of the UPS to the remote power panel  22 . In other embodiments, a busbar-to-busbar connection is employed to connect the UPS to the power busway while a cable connection is employed to connect the tap box  36  to the remote power panel  22 . 
         [0028]    The system  8  illustrated in  FIG. 1  can operate at any voltage level suitable for power distribution, for example, low voltage power distribution having a nominal operating voltage of 600 volts or less. In one embodiment, the power distribution system  8  operates at a nominal voltage of 400 volts. Further, embodiments can be employed to distribute AC power or DC power depending upon the application. 
         [0029]    In some embodiments, the tap boxes  36  may include plug-in connections. Further, the tap boxes may include overcurrent protection provided by either or both a circuit breaker and a fuse. In accordance with one embodiment, the tap box  36  includes a fuse with a rating of 30 amps, 60 amps or 100 amps and does not include a circuit breaker. In accordance with another embodiment, the tap box  36  includes a circuit breaker but does not include a fuse. Further, where the tap box  36  includes a fuse, the tap box can also include a knife switch that allows a mechanical disconnection between the power busway  14  and the bustap  38 . 
         [0030]    According to some embodiments, the overall approach illustrated by the system  8  of  FIG. 1  provides a flexible and more efficient installation of a power distribution system. According to some embodiments, the approach is particularly advantageous for supplying power to IT load where a plurality of relatively small individual loads included in each rack result in a high power density. 
         [0031]    The specific configuration of the equipment racks  24  can vary depending upon the application. In some embodiments, the power distribution units are mounted on to wheels such that they can be rolled into a location adjacent a connection to the power busway  14 . This approach allows the power distribution units to be individually aligned with the power busway taps even where the location of the tap box  36  is fixed. 
         [0032]      FIG. 2  illustrates a power distribution system  50  that employs a transformer to change the voltage supplied at the output of the UPS before the UPS output is coupled to the power distribution units. For example, the system  50  may distribute power to the power distribution units  12  at a voltage that differs from the UPS output voltage. Some example UPS output voltages include any of 400 volts, 240 volts, 480 volt/240 volts and 415/240 volts. As illustrated here, the UPS includes the first enclosure  16 , the second enclosure  18  and the third enclosure  20  as previously described concerning  FIG. 1 . The power distribution system  50  also includes a first power busway  14  directly connected to an output of the UPS  10 . In addition, the power distribution system  50  includes a second power busway  15 . The power distribution system also includes a transformer unit  52 . In the illustrated embodiment, the transformer unit  52  includes a transformer to create a utilization voltage that differs from the output voltage of the UPS. For example, the secondary of the transformer included in the power distribution  52  can be 280/120 volts where the output voltage of the UPS is 415/240 volts or another voltage that differs from 208/120. 
         [0033]    The system  50  can include a plurality of power distribution units  12 A,  12 B and a plurality of transformer units  52 A,  52 B. The system  50  can also include one or more first tap boxes  54 A,  54 B and one or more second tap boxes  36 A,  36 B. 
         [0034]    To maintain a modular approach, transformer units can be included or added to the power distribution system  50  to meet increased electrical loads. For example, in the illustrated embodiment, a transformer unit  52 B is included to supply a second plurality of power distribution units. According to one embodiment, this allows for moderately sized transformers included in each of the transformer units where transformers can be more efficiently operated closer to their maximum rating with fewer losses. Further, the first tap boxes  54 A,  54 B can provide for connection of the individual transformer units  52 A,  52 B to the first power busway  14 . The second power busway  15  provides for a connection of the secondary of the transformer to included in the transformer unit  52  to the corresponding power distribution unit  12 . 
         [0035]    According to this embodiment, the second tap boxes  36 A,  36 B can be employed to provide for a connection of individual ones of the multiple power distribution units  12 A,  12 B to the second power busway  15 . According to one embodiment, a rated current of the power busway  14  matches a rated current output of the UPS  10 . The second power busway  15 , in various embodiments, may or may not be of the same construction and ratings of the first power busway  14 . For example, in one embodiment, the current rating of the second power busway  15  differs from the current rating of the first power busway  14  as a result of the difference in operating voltage of the two power busways and/or because a single power busway  15  may be supplying only a portion of the total rated output of the UPS  10 . For example, as illustrated in  FIG. 2 , a second transformer unit  52 B can be connected to the power busway  14  at the tap box  54 B. A second power busway  15 B can be connected to the secondary of the transformer included in the power distribution  52 B where the power busway  15 B connects a second plurality of power distribution units to the output of the UPS via the transformer unit  52 B and power busway  14 . Further, in some embodiments, the nominal current rating of the second power busway can be sized to match the current rating of the transformer included in the transformer unit to which it is connected. 
         [0036]    According to one embodiment, the transformer units  52 A,  52 B each include a 500 KW transformer. The transformer units can be sized to match the anticipated demand of the connected load. In addition, where multiple transformer units  52 A,  52 B are included in the power distribution system  50 , the transformer units can be sized differently from one another. 
         [0037]      FIG. 3  illustrates a busbar-to-busbar connection of the power busway  14 , for example, power busway  14  as illustrated in  FIGS. 1 and 2 , to a UPS in accordance with one embodiment. As illustrated, the connection is included in the electrical equipment enclosure, for example, the third enclosure  20  included in the UPS. According to the embodiment, illustrated in  FIG. 3 , the power busway includes a riser  60 . The power busway including the riser  60  houses a plurality of busbar  62  including one or more phase conductors, a neutral conductor, and a ground conductor. to The termination is completed within the enclosure by connecting the busway riser  60  to the plurality of busbar  62  in the enclosure  20  where the plurality of busbar  62  are provided at the output  33  of the UPS. 
         [0038]    In various embodiments, the plurality of busbar  62  can be manufactured from any type of electrical conductor such as copper, aluminum, or alloys of the preceding as well as other conductive metals. Further, the busway can include a fewer or a greater number of conductors. For example, the plurality of busbar  62  may include a different quantity of phase conductors. In addition, the plurality of busbar may or may not include either of a neutral conductor or a ground conductor. 
         [0039]      FIG. 3  also illustrates a busway termination  64  that provides a terminus of the power busway, for example, a terminus of the power busway  14 . For example, the busway termination  64  may be provided with a flanged end as illustrated in  FIG. 3  to provide room for the bolted busbar connections that complete the termination of the busway riser  60  at the output  33  of the UPS. 
         [0040]    Other mechanical configurations of busway termination  64  may be employed to provide a busbar-to-busbar connection between a terminus of the power busway and the UPS. In the illustrated embodiment, each of the phase conductors and the neutral conductor include a plurality of busbars (2) that allows for an increased current carrying capacity for each of the conductors. Alternatively, a single busbar may be used for each conductor in the plurality in the power busway. Further, the power busbar and UPS output may include only a three pole system with or without a ground bus. The power busway may be supplied to meet a variety of applications, for example, the power busway may be rated anywhere from 225 amps to 5000 amps and the plurality of busbar  62  can be sized to carry the rated current for the selected application. 
         [0041]    The busway riser  60  may be included as part of a horizontal riser that initially extends in a vertical direction from a top of the third enclosure  20  then is redirected through the use of a busway elbow to make a connection to a horizontal run to a power busway. According to another embodiment, the busway riser  60  may be included in a vertical riser that extends as installed in a vertical direction through a series of different vertical elevations or floors of a facility. 
         [0042]    As mentioned above, variations in the location of the enclosures  16 ,  18  and  20  within the UPS  10  are contemplated. As illustrated in  FIGS. 1-3 , the third enclosure  20  is an end unit, however, alternate embodiments can be employed provided that the output of the UPS  10  can be connected to terminus of the power busway  14 . In one embodiment, the third enclosure  20  is centrally located among the electrical enclosures included in the UPS  10 . According to another embodiment, a third enclosure  20  is not employed. Instead, the busway riser  60  connects to the UPS  10  at either the first enclosure  16  or the second enclosure  18 . Accordingly, in one embodiment, the busway termination  64  is located at the top of the second enclosure  18 . In an alternate embodiment, the busway termination  64  is located at the top of the first enclosure  16 . 
         [0043]      FIG. 4  illustrates a termination  65  between an output of the UPS  10  and the power busway  14 . The termination  65  provides a mechanical connection as well as an electrical connection between the UPS  10  and the power busway  14 .  FIG. 4  illustrates a single bolted busbar-to-busbar connection which can be included in a plurality of busbar-to-busbar connections, for example, the plurality of connections illustrated in  FIG. 3 . In the illustrated embodiment, the termination includes a first busbar  66 , a second busbar  68 , and a tie connector  67 . In addition, the termination includes one or more washers  72  and a fastener  70 . In the illustrated embodiment, the busbar  66  represents, or is included in, the terminus of the power busway. Further, the busbar  68  is connected to the UPS and is included as a part of the UPS in some embodiments. For example, the busbar  68  can be connected to, or provided at, the output  33  referred to  FIG. 1 . 
         [0044]    In the illustrated embodiment, the fastener  70  includes a nut and a bolt. According to one embodiment, the washer(s)  72  are conical washers. In a further embodiment either or both of the fastener  70  and the washer(s)  72  are Grade 5 hardware. 
         [0045]    A different style or type of fastening hardware can be employed provided it is suitable to maintain the electrical connection between the busbar  66  and the busbar  68  through thermal cycling as a result of changes in the demand of the connected load and/or changes in ambient temperature. 
         [0046]    The tie connector  67  can be employed to connect multiple busbar that are included for the same phase, neutral and/or ground conductor, respectively. For example, referring again to  FIG. 3 , each of phase A, phase B, phase C, and the neutral include two busbar connected together by a tie connector  67 . Accordingly, in embodiments where these phase and neutral conductors each include multiple busbars, the tie connector  67  can be employed to connect the multiple busbars of the same conductor to one another. 
         [0047]    Referring now to  FIG. 5 , a busway termination  64  is illustrated in greater detail. According to the illustrated embodiment, the busway termination includes the plurality of busbar  62  and a flange  74  that is employed to secure the busway riser  60  to the UPS, for example, to the second enclosure  20 . Here, a four pole power distribution system is represented. As mentioned above, however, three pole systems or other alternate configurations can be employed in various embodiments. 
         [0048]    The flange  74  attaches at a wall or roof to the third enclosure  20  via one or more fasteners  76 . The flange  74  attaches to a corresponding flange provided at the third enclosure  20 . In some embodiments, one or more gaskets are used to provide a seal (for example, a dust tight or weather tight seal) where the flange  74  is attached to the second enclosure. As mentioned above, the busway termination  64  can be included at the terminus of the busway riser  60 . 
         [0049]    The busway termination  64  can be connected to the UPS output  33  via a bolted connection of the plurality of busbar  62  to a corresponding plurality of busbar provided at the UPS output  33 , see for example,  FIG. 3 . In some embodiments, the resulting connection can be included in a complete busbar-to-busbar connection of the UPS output  33  to one or more power distribution units  12  without the use of cabling to complete the connection. 
         [0050]    Embodiments can be employed with a wide variety of UPS designs including on-line UPSs, line-interactive UPSs, delta conversion UPSs, flywheel UPSs, motor-generator/battery UPSs and engine-coupled UPSs as some examples. 
         [0051]    Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.