Patent Abstract:
A power transfer device adapted for interconnection with the electrical system of a building includes a cabinet, a set of switches mounted to the cabinet, and a first set of wires for connecting the switches to an electrical distribution panel associated with the building electrical system. The power transfer device includes a terminal compartment associated with the cabinet, a set of power input terminals located within the terminal compartment, and a cover removably connected to the cabinet for alternatively preventing and permitting access to the terminal compartment. The cover is provided with a coupling arrangement adapted to be interconnected with the power input terminals, for selectively receiving an input member on one end of a flexible cord in electrical communication with a source of auxiliary power.

Full Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to a power inlet arrangement for providing power to the electric system of a building, such as power supplied from a standby generator. 
     Portable generators may be used in certain situations to feed electrical power to residential and commercial load circuits during a utility power outage. These systems frequently include a power inlet box adapted for interconnection with the generator. The power inlet box is typically mounted to the exterior of a building. The power inlet box is connected to a transfer switching mechanism which continues the electrical path through circuit breakers associated with the transfer switching mechanism, to supply power to certain selected circuits of the load center as determined by the transfer switching mechanism circuit breakers. The circuits of the transfer switching mechanism are wired to selected circuits of the load center, through wiring housed within a conduit extending between the load center and the transfer switching mechanism. 
     The present invention relates to a power transfer arrangement such as is disclosed in U.S. Pat. No. 5,895,981, issued Apr. 20. 1999, the disclosure of which is hereby incorporated by reference. In the &#39;981 patent, a power transfer switching mechanism for interposition between a remote power inlet box and the electrical load center of a building includes a terminal compartment for receiving power input wires connected to the remote power inlet box. The switching mechanism includes a cabinet defining an internal cavity within which a series of switches are mounted. The cabinet further defines a terminal compartment, and a terminal assembly is disposed within the terminal compartment. The terminal compartment is accessible through an opening associated with the cabinet, and a cover is selectively positionable over the opening to provide or prevent access to the terminal compartment. A series of wires are interconnected between the terminal assembly and the switches, and power input wiring is received within the terminal compartment and interconnected with the remote power inlet box. The ends of the power input wires are engageable with the terminal assembly for establishing a direct electrical connection between the remote power inlet box and the switches of the switching mechanism. 
     While the above-described power transfer switching mechanism provides an extremely convenient and simple arrangement for establishing a direct, hardwired connection with the power inlet box, it is sometimes desirable to provide a power transfer switching mechanism having a power input receptacle in its front panel. With this modification, the generator power cord may be plugged into the power input receptacle. Alternatively, the remote power inlet box may be wired to a power cord connected to a junction box, and the power cord may be selectively engageable with the power input receptacle of the power transfer switching mechanism. Although the broad concept of providing power input receptacles on a power transfer switching mechanism is well known, it is desirable to modify the power transfer switching mechanism described in the aforementioned copending patent application, to provide a selective rather than a hardwired connection with the power inlet box. 
     It is an object of the present invention to provide a transfer switching mechanism having a removable access cover provided with a power input receptacle for providing input power to the transfer switching mechanism from a generator or from a power inlet connected with the generator. It is a further object of the present invention to provide such a transfer switching mechanism which ensures that a reliable selective connection is established with the generator when power is supplied to a transfer switching mechanism. Another object of the present invention is to provide a transfer switching mechanism which is simple to install and which operates generally similarly to prior art transfer switching mechanisms. 
     The invention contemplates an improvement in a power transfer arrangement for supplying power from a generator to the electrical system of a building. The power transfer arrangement includes a power inlet arrangement for interconnection with the generator for receiving power therefrom, and a power transfer device separate from the power inlet arrangement adapted for interconnection with the building electrical system. The invention resides in a power input terminal arrangement in the power transfer device in combination with a removable cover associated with the power transfer device for preventing access to the power input terminal arrangement. The cover is provided with a power input receptacle connected to the power input terminal arrangement for selectively receiving a plug connector in electrical communication with the power inlet arrangement. The power transfer device includes a cabinet having a front panel to which is mounted a set of switches for controlling the supply of power from the power transfer device to the building electrical system, and set of switches are electrically connected to the power input terminal arrangement. The power transfer device further includes a set of power input terminals for establishing a direct electrical connection between the power inlet arrangement and the power transfer device. The power input terminals are located within a power input terminal compartment defined by the cabinet at a location spaced from the set of switches. The cabinet defines an opening, providing access to the power input terminal compartment. The cover is positionable over the opening, and removably engageable with the cabinet for selectively closing, the opening, for preventing access to the power input terminal compartment. The opening, providing access to the power input terminal compartment is defined in part by a rearwardly extending edge of the front panel. The cover has a rearwardly extending ledge engageable with the rearwardly extending edge of the front panel, and a vertically extending wall depending from the ledge and engageable with an end wall of the cabinet. The ledge is recessed to accommodate the power input terminals when the cover is in position covering the opening. The power input receptacle extends through and is fixed to the vertically extending wall of the cover. The power input receptacle includes a cylindrical body and a circular collar adapted to overlie the vertically extending wall of the cover. The power transfer device also includes a set of power input wires extending between the power input receptacle and the power input terminals. 
     The invention further contemplates an improvement in a power transfer device adapted for interconnection with the electrical system of a building and including a cabinet, a set of switches mounted to the cabinet, and a first set of wires for connecting the switches to an electrical distribution panel associated with the building electrical system. The invention is in the form of a terminal compartment associated with the cabinet, a set of power input terminals located within the terminal compartment, and a cover removably connected to the cabinet for alternately preventing and permitting access to the terminal compartment. The cover is provided with a coupling arrangement interconnected with the power input terminals and adapted to selectively receive an input member on one end of a flexible cord in electrical communication with a source of auxiliary power. A set of power input wires enables interconnection of the coupling arrangement with the power input terminals. The power input terminals are connected to the switches by a second set of wires. The cabinet includes a set of tabs spaced along an end wall thereof, the tabs having apertures formed therein. The cover includes a set of openings alignable with the apertures in the tabs. A set of fasteners is passed through the openings in the cover and is threadably engageable with the apertures in the tabs. One of the fasteners is used to secure the coupling arrangement to the cover. 
     The invention also relates to a method for constructing a power transfer device for supplying power to the electrical system of a building from a generator in electrical communication with a separate power inlet arrangement. The method includes the steps of providing a cabinet having a power terminal arrangement; equipping the cabinet with a front panel including a plurality of switches electrically connected to the power input terminal arrangement for controlling the supply of power from the power transfer device to the building electrical system; and supplying the cabinet with a cover removably connected thereto for alternately preventing and permitting access to the power input terminal arrangement. The cover is provided with a power input receptacle connected to the power input terminal arrangement for selectively receiving a plug connector in electrical communication with the power inlet arrangement. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is a schematic representation showing a prior art power inlet arrangement for interconnecting a portable power generator with an electrical panel associated with a building; 
     FIG. 2 is a schematic representation similar to FIG. 1, showing the power transfer arrangement constructed according to the invention, for interposition between a remote power inlet and the electrical panel; 
     FIG. 3 is a partial front elevation view showing the bottom portion of the power transfer arrangement of FIG. 2 with the access cover removed; 
     FIG. 4 is a partial section view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a partial front elevational view showing the bottom portion of an alternative power transfer arrangement in which the access cover is provided with an optional plug connector and is shown in an installed condition; 
     FIG. 6 is an exploded view of the access cover and the bottom portions of the alternative power transfer arrangement shown in FIG. 5; 
     FIG. 7 is a partial sectional view taken on line  7 — 7  of FIG. 5; and 
     FIG. 8 is a view similar to FIG. 5 but showing part of the access cover broken away to view the components in the bottom portion of the alternative power transfer arrangement. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a prior art power inlet arrangement for interconnecting a portable generator  10  with a main electrical panel or load center  12  located in the interior of a building  14 . In the prior art power inlet arrangement of FIG. 1, a manual power transfer panel  16  is mounted adjacent main panel  12 , and is interconnected therewith via a series of wires enclosed by a conduit  18  extending between main panel  12  and transfer panel  16 . Transfer panel  16  may illustratively be a panel such as that manufactured by Reliance Time Controls, Inc. of Racine, Wis. under the designation GEN/TRAN (e.g. Model 20216 or any other satisfactory model). 
     A power inlet box  20  is mounted to the wall of building  14 , shown at  22 . Power inlet box  20  includes an external housing including a series of walls such as  24 , and a recessed power inlet  26  mounted to a front wall of the housing. A cover  28  is mounted to the front wall of the housing via a hinge structure, and is movable between an open position as shown in FIG. 1 and a closed position in which cover  28  encloses recessed power inlet  26  when not in use. A conduit  30  extends between inlet box  20  and a junction box  32 , and a flexible cord  38  is attached at one end to junction box  32 . At its opposite end, flexible cord  38  has a connector  42  engageable with a power inlet receptacle provided on transfer panel  16 . Appropriate wiring and connections are contained within inlet box  20 , conduit  30  and junction box  32  for providing an electrical path between inlet box  20  and transfer panel  16  when cord  38  is engaged with the inlet receptacle of transfer panel  16 . 
     A power cord  44  extends between generator  10  and power inlet box  20 . Cord  44  includes a plug  46  at one end, which is engageable with the power outlet of generator  10 . Cord  44  further includes a connector  48  at the end opposite plug  46 . Connector  48  is engageable with recessed power inlet  26  for transferring power generated by generator  10  to power inlet box  20 , which is then supplied through the wiring in conduit  30 , junction box  32 , cord  38  and connector  42  to transfer panel  16 , and from transfer panel  16  through the wiring in conduit  18  to main panel  12 . In this manner, generator  10  functions to provide power to selected circuits of main panel  12  during a power outage. In this arrangement, it is necessary for the user to first connect cord  38  to the power input of transfer panel  16  utilizing connector  42 , and to then exit the building, connect cord  44  between generator  10  and power inlet  20 , and then commence operation of generator  10 . This two-step procedure inevitably consumes a certain amount of time and inconvenience by first having to engage cord  38  with transfer panel  16  within building  14  and then exiting the building to carry out the various operations associated with connection and startup of generator  10 . 
     Transfer panel  16  includes a socket for receiving connector  42 , which is wired to a series of switches on transfer panel  16 , in a manner as is known. The switches of panel  16  control the supply of power to load center  12  when power is supplied from generator  10  to transfer panel  16  by engagement of connector  42  with the socket of transfer panel  16 . In the construction of transfer panel  16 , the socket is wired directly to the switches within the interior of transfer panel  16 , in a manner as is known. 
     FIG. 2 illustrates a power transfer arrangement in accordance with the invention for providing power from generator  10  to main electrical panel  12 . In the power transfer arrangement of FIG. 2, power inlet box  20  and main electrical panel  12  have the same function and construction as in the prior art power transfer arrangement of FIG.  1 . 
     In the power transfer arrangement of FIG. 2, a power transfer switching mechanism  50  is interposed between load center  12  and inlet box  20 . Power transfer switching mechanism  50  includes a cabinet defining a pair of side walls  52 ,  54 , a top wall  56  extending between the upper ends of side walls  52  and  54 , a bottom wall  58  (FIG. 3) extending between and interconnecting the lower ends of side walls  52  and  54 , a partial height front panel  60  and a rear panel  62  (FIG.  4 ). Walls  52 - 58 , in combination with front panel  60  and rear panel  62 , define an upper cavity  64  within which a series of circuit breakers or switches  66  are located. 
     Front panel  60  is bent rearwardly at its lower end to form an intermediate transverse wall  68  which defines the lower extent of upper cavity  64 . A terminal compartment  70  is defined by intermediate transverse wall  68  in combination with bottom wall  58 , the lower portions of side walls  52  and  54 , and the lower portion of rear panel  62 . Terminal compartment  70  is accessible through an opening below front panel  60 . A cover  72  (FIG. 2) is sized so as to enclose the opening of terminal compartment  70 . Cover  72  includes a pair of openings in alignment with openings  73  formed in a pair of tabs  74  mounted to bottom wall  58 , to enable cover  72  to be mounted to bottom wall  58  utilizing threaded fasteners  75 ,  77  (FIG. 2) which extend through the openings in cover  72  and into engagement with the openings  73  in tabs  74 . In this manner, cover  72  is selectively engaged with bottom wall  58  to provide access to terminal compartment  70 , and is connected to bottom wall  58  so as to prevent access to terminal compartment  70 . 
     A terminal assembly  76  is mounted to a vertical plate  78 , which is mounted at its ends to intermediate transverse wall  68  to fix terminal assembly  76  in position relative to intermediate transverse wall  68 . Terminal assembly  76  is of conventional construction, including a series of cylindrical receivers  80 , each of which defines a downwardly facing opening. Each receiver  80  includes an outwardly extending cylindrical member  82  extending perpendicularly to receiver  80 , defining a passage for receiving a threaded member, the head of which is shown at  84  (FIG.  3 ). Receivers  80  are accessible from, and in communication with, terminal compartment  70 . Terminal assembly  76  further includes a series of upwardly opening cylindrical receivers  86 , which are disposed within upper cavity  64 . Each upper cylindrical receiver  86  includes a cylindrical member  88  which receives a threaded member (not shown). 
     Terminal assembly  76  may illustratively be a terminal assembly such as is available from Atech Corp. of Somerville, N.J., under its Model No. TSF/16, although it is understood that any other satisfactory terminal arrangement could be employed. In a terminal arrangement such as this, receivers  80  and  86  are formed of a molded plastic material integrally with cylindrical members  82  and  88 . These components surround metal contact assemblies, with one of the contact assemblies being located in both a cylindrical receiver  80  and a cylindrical receiver  86 . In this manner, an electrical connection to terminal assembly  76  is made by inserting a bare wire end into the open lower end of receiver  80  and tightening the threaded member utilizing its head  84 , to establish an electrical connection with the wire via the metal contact enclosed within cylindrical receiver  80 . A similar operation is employed to connect a wire end to the contact enclosed by the opposed cylindrical receiver  86 , so as to establish a connection between the wires connected to the terminal assembly in this manner. 
     As shown in FIG. 4, a wire such as  90  is connected to each upper cylindrical receiver  86  at one end. Two of wires  90  feed bus bars (not shown), which in turn are interconnected with switches  66  to provide power to switches  66 . A third one of wires  90  is a neutral wire which is connected to the neutral of load center  12 , and a fourth one of wires  90  is a ground wire attached to the frame of transfer switching mechanism  50 . 
     Referring to FIGS. 2 and 3, a conduit  92  extends between power inlet box  20  and switching mechanism  50 . Conduit  92  encloses a series of power input wires  94  (FIG.  3 ), and extends through a knock-out opening formed in the lower portion of side wall  52  via a conventional nipple  96  and lock nut  98 . As can be appreciated, an input wire conduit such as  92  could also be connected through a knock-out opening in side wall  54 , as shown in phantom in FIG. 3, or in knock-out openings in bottom wall  58  or the lower portion of rear panel  62 . 
     The ends of power input wires  94  are connected to terminal assembly  76  by placing the bare end of each wire  94  into one of receivers  80  and tightening the associated threaded member, as explained previously, to establish an electrical connection with a contact member enclosed by one of the cylindrical receivers  80 . In this manner, input power is supplied from remote power inlet  20  to terminal assembly  76 , which is subsequently transferred from terminal assembly  76  to wires  90  and thereby to switches  66 , as explained previously. This arrangement enables a person installing switching mechanism  50 , such as an electrician or do-it-yourself homeowner, to establish a direct electrical connection between remote power inlet box  20  and switching mechanism  50 , without the need for connecting a flexible cord to a power input receptacle as in the prior art. In this manner, after generator power cord  44  is plugged into remote power inlet box  20 , the only necessary operation in connection with switching mechanism  50  to enable transfer of power from generator  10  to load center  12  is to place switches  66  in the appropriate position so as to transfer power to load center  12  as desired in response to operation of generator  10 . 
     Output wires from switches  66 , shown at  99 , extend through terminal compartment  70  to a conduit fitting  100  secured to bottom wall  58 , for routing the wires through conduit  18  to load center  12 . Other wires extend through terminal compartment  70 , such as neutral and ground wires as well as input wires from load center  12 . 
     It can thus be appreciated that the provision of terminal compartment  70  provides an extremely convenient and simple arrangement for establishing a direct, hardwired connection between power inlet box  20  and power transfer switching mechanism  50 . The user or installer simply must remove cover  72  to gain access to terminal compartment  70  for connecting or disengaging power input wires  94  to or from terminal assembly  76 . Terminal compartment  70  also provides a convenient cavity to facilitate pulling of wires through conduit  92 . Once the user has completed the necessary operations in terminal compartment  70 , the user simply replaces cover  72  as described previously, to thereby prevent access to terminal compartment  70 . 
     FIGS. 5-8 disclose an alternative embodiment of the power transfer arrangement  50 ′ having substantially identical components as previously described in FIGS. 2-4 except for removable access cover  72 ′ and power input wires  94 ′. In this power transfer arrangement  50 ′, cover  72 ′ has a rearwardly extending ledge  102  which is engageable beneath the transverse wall  68  of front panel  60 , and a vertically extending wall  104  which depends downwardly from ledge  102  and is engageable against cabinet side walls  52 ,  54  and end wall  58 . As seen in FIG. 6, ledge  102  includes a central recess  105  for accommodating the power input terminals  80 ,  82 . It should be appreciated that cover  72  also includes ledge  102 , vertical wall  104  and central recess  105 . 
     Cover  72 ′ further includes a pair of openings  106 ,  108  in alignment with openings  73  formed in the pair of tabs  74  projecting from bottom wall  58  to enable cover  72 ′ to be secured to bottom wall  58  by threaded fasteners  75 ,  77  which extend through the cover openings  106 ,  108  and into threaded engagement with tab openings  73 . 
     An opening  110  is formed in wall  104  adjacent one of its ends. A power input socket, shown generally at  112 , is engaged with wall  104  at opening  110 . Socket  112  is of conventional construction for receiving a plug connertor in a power transfer panel, and includes a cylindrical body  114  and a circular collar  116 . Cylindrical body  114  extends through opening  110  such that circular collar  116  overlies and engages the front surface of wall  104 . A pair of threaded fasteners  118 ,  120  extend through aligned openings in collar  116  and in wall  104  adjacent opening  110 , to mount socket  112  to wall  104 . In addition, an opening is formed in collar  116  in alignment with opening  108 , and fastener  77  extends therethrough and into engagement with opening  73  in tab  74  adjacent socket  112  for securing socket  112  to wall  104 . 
     Socket body  114  defines an outwardly open internal cavity which is closed at its inner end by an end wall  122 . A series of male prongs  124  extend from end wall  122  into the internal cavity defined by socket body  114 . Power input wires  94 ′ are interconnected with prongs  124  and with power input terminals  80 , for establishing an electrical connection between prongs  124  and switches  66 . 
     In a manner as is known, prongs  124  are adapted for engagement with the female end of a plug connector. In an arrangement such as illustrated in FIG. 1, connector  42  or cord  38 , which extends from junction box  32 , may be engaged with prongs  124  for supplying power to power transfer arrangement  50 ′ from generator  10 . Alternatively, a power cord may extend directly from generator  10  through an opening in wall  22 , such as a window, and a connector at the end of such a cord may be engageable with prongs  124  for supplying power directly to power transfer arrangement  50 ′ from generator  10 . 
     It can thus be appreciated that a manufacturer can provide either a hardwired power transfer switching mechanism  50  or a socket-type power transfer switching mechanism  50 ′ simply by mounting either cover  72  or cover  72 ′ to the cabinet over terminal compartment  70 . This provides significant efficiencies in manufacturing by providing a large number of common components for two different models. In addition, it can be appreciated that the hardwired version of power transfer switching mechanism  50  can be retrofit to provide a socket-type switching mechanism  50 ′ by replacing cover  72  with cover  72 ′, or a socket-type power transfer switching mechanism  50 ′ can be transformed into a hardwired power transfer mechanism  50  by replacing cover  72 ′ with cover  72  in the field. 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.

Technology Classification (CPC): 7