Abstract:
An apparatus includes a housing portion comprising a back panel, side panels, and a front panel, the back panel and side panels partially defining a cavity having an access orifice, the side panels partially defining an entry area to the access orifice, the front panel arranged to at least partially obscure the entry area to the access orifice and pivot about an axis of rotation, and a first switch disposed in the cavity including a first contact portion secured to the housing portion, and a removable contact portion connected to the front panel.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to fuses, and particularly to a switch box arrangement that includes fuses. 
     Traditional alternating current (AC) switch boxes often include an array of switches and fuses that correspond to each phase of a multi-phase electrical distribution system. The switches are arranged to disconnect the line side of the fuses from the incoming voltage of a respective phase. 
     The switch boxes often include an external lever that is mechanically linked to the switches such that actuating the external lever opens and closes the switches. In operation, a technician operates the external lever to open the switches, thereby isolating the fuses prior to opening an access panel or door that exposes the fuse and switches for maintenance or troubleshooting. 
     In some electrical systems, such as systems that receive electrical power from an electrical grid and electrical power from an on-site power source, a voltage may be present in the fuses if the fuses are not completely electrically isolated from the system. It is desirable to ensure that a technician has isolated the fuses from the system prior to accessing the switch box. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention an apparatus includes a housing portion comprising a back panel, side panels, and a front panel, the back panel and side panels partially defining a cavity having an access orifice, the side panels partially defining an entry area to the access orifice, the front panel arranged to at least partially obscure the entry area to the access orifice and pivot about an axis of rotation, and a first switch disposed in the cavity including a first contact portion secured to the housing portion, and a removable contact portion connected to the front panel. 
     According to one aspect of the invention a system includes a power source, and an apparatus comprising a housing portion comprising a back panel, side panels, and a front panel, the back panel and side panels partially defining a cavity having an access orifice, the side panels partially defining an entry area to the access orifice, the front panel arranged to at least partially obscure the entry area to the access orifice and pivot about an axis of rotation, and a first switch disposed in the cavity including a first contact portion secured to the housing portion, and a removable contact portion connected to the front panel, the first switch is electrically connected to the power source. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  illustrates a block diagram of an exemplary embodiment of an electrical system, in accordance with an embodiment of the invention. 
         FIG. 2  illustrates an exemplary embodiment of a switch box, in accordance with an embodiment of the invention. 
         FIG. 3  illustrates an exemplary embodiment of a removable contact member in accordance with an embodiment of the invention. 
         FIG. 4  illustrates a detailed, partially transparent view of the region  4  of  FIG. 2 . 
         FIG. 5  illustrates a top partially cut-away view of the exemplary embodiment in accordance with an embodiment of the invention. 
         FIG. 6  illustrates another top partially cut-away view of the exemplary embodiment in accordance with an embodiment of the invention. 
         FIG. 7  illustrates an alternate exemplary embodiment of a switch box, in accordance with an embodiment of the invention. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a one-line block diagram of an exemplary embodiment of an electrical system (system)  100 . The system  100  includes a direct current (DC) power source  102  that may include, for example, an array of solar cells, a wind turbine, or other type of generator or power source. A switch box  104  is electrically connected to the DC power source  102  and an inverter  108 . The inverter  108  is operative to invert DC power into AC power. The inverter  108  is electrically connected to an electrical load  110 , such as, for example, electrical equipment including motors, lighting, and heating and air conditioning systems, and an AC grid  112 . While the system  100  is depicted in  FIG. 1  as a one-line block diagram, it will be appreciated by one skilled in the art that such a depiction also represents a multi-phase electrical distribution system, such as a three-phase or three-phase with switching neutral electrical system, for example. 
     The switch box  104  includes a fuse  116  that may include any type of fuse such as, for example, a photovoltaic (PV) fuse that is electrically connected to the DC power source  102  and the inverter  108 . The switch box  104  includes a first switch  114  that is electrically connected to the fuse  116  and the DC power source  102 . The arrangement of the first switch  114  allows the fuse  116  to be electrically isolated from the DC power source  102  when the first switch  114  is in an open position or state. A second switch  118  is electrically connected to the fuse  116  and the inverter  108 . The arrangement of the second switch allows the fuse  116  to be electrically isolated from the inverter  108  when the second switch  218  is in an open position or state. The first switch  114  may be mechanically linked to an actuating linkage (not shown in  FIG. 1 ) with an external lever that allows a technician to manually open or close the first switch  114  using a single lever prior to accessing the switch box  104 . 
     The second switch  118  is a pull-out disconnect switch having biased contacts secured to a housing that is connected to the switch box  104  and a removable contact that when positioned between and in contact with the biased contacts defines a current path through the biased contacts and the removable contact. 
     The electrical connection between the inverter  108  and the AC grid  112 , and in some instances, the connection between the inverter and the load  110 , may result in a “back feeding” state where a voltage may be present at the fuse  116  even if the fuse  116  is isolated from the DC power source  102  (i.e., the switch  114  is in an open position or state). The second switch  118  allows the fuse  116  to be isolated from the inverter  108 . The combination of the first switch  114  and the second switch  118  allows the fuse  116  to be isolated from both the DC power source  102  and the inverter  108  when the first switch  114  and the second switch  118  are in an open position or state. 
     Previous examples of switch boxes included labels that would remind a technician to test the fuses with a volt meter to ensure that there is no voltage present at the fuse  116  prior to accessing the fuse  116 . The embodiments described below improve the safety of the switch boxes by electrically isolating the fuse  116  by opening both the first switch  114  and the second switch  118 . The switch boxes may include an arrangement such that an access panel or door is mechanically prevented from being opened prior to opening the first switch  114  and the second switch  118 . 
     In this regard,  FIG. 2  illustrates an exemplary embodiment of a switch box (connection box)  202 . The switch box  202  is arranged to be used in a multi-phase power system. Though the switch box  202  of the illustrated embodiment is arranged to be used in a three-phase power system, alternate embodiments may include similar arrangements that may be used in, for example, a single-phase power system or a multi-phase power system having any number of phases. 
     The switch box  202  includes a housing portion  204  having a rear panel  206 , and side panels  208  that define a cavity  210  having an access orifice  211  defined by exposed edges  217  of the side panels  208 , the housing portion  204  includes a front panel  212  that encloses the cavity  210  and the access orifice  211  when arranged in a closed position. The front panel  212  may be secured to the side panels  208  of the housing portion with, for example, fasteners, a hinge arrangement, a combination of a hinge arrangement and fasteners, or any suitable combination of hooks, clasps, or clips. Switches  214  and  118  are arranged in the cavity  210 . The switch  214  is connected to an actuating lever  216  with a mechanical linkage arrangement  213  such that the movement of the actuating lever  216  changes the position or state of the switch  214 . The mechanical linkage arrangement  213  or the actuating lever  216  may include an interlock assembly  226  that interacts with the front panel  212 , and prevents the front panel  212  from being opened (exposing the cavity  210 ) unless the actuating lever  216  is in a position that places the switch  214  in an open state or position. Thus, an operator may be prevented from opening or removing the front panel  212  prior to placing the switch  214  in an open state or position. Each of the switches  214  and  218  includes a terminal that may be connected to an electrical cable or line. The switches  214  and  218  are electrically connected to corresponding fuse holder assemblies  219 . Each of the fuse holder assemblies  219  includes a first fuse holder portion  220  and a second fuse holder portion  222 . The first fuse holder portion  220  secures a first end of a fuse  224  and is electrically connected to a corresponding switch  214 . The second fuse holder portion  222  secures a second end of the fuse  224  and is electrically connected to a terminal that is electrically connected to the second switch  218 . An electrical path is defined by the terminals of a switch  214 , the switch  214  contacts, the first fuse holder portion  220 , the fuse  224 , the second fuse holder portion  222 , terminals of the second fuse holder portion  222 , the second switch  218  stationary contacts, the second switch  218  removable contacts, and the terminals of the second switch  218 . 
     The second switch  218  is connected to the housing portion  204 . The second switch  218  includes a stationary contact portion  228  and a removable contact member  230 . The stationary contact portion  228  that includes pairs of biased conductive contacts that are secured to the stationary contact portion  228 . 
       FIG. 3  illustrates an exemplary embodiment of a removable contact member  230  that includes conductive contacts  302 , a housing portion  304 , and a handle portion  306 . 
       FIG. 4  illustrates a detailed, partially transparent view of the region  4  (of  FIG. 2 ). In this regard, the removable contact member  230  is illustrated engaging a retaining member  402  that is connected to an inner surface  231  of the front panel  212 . The retaining member  402  in the illustrated embodiment includes a metallic clip that may be formed from stamped or bent sheet metal material and connected to the inner surface  231  of the front panel with, for example, fasteners or another joining means such as welding or brazing. The retaining member  402  is not limited to the embodiment shown, and may include any type of clip, fastener, bracket, or retaining arrangement that engages and retains the removable contact member  230 . In the illustrated embodiment, the retaining member  402  is operative to engage the handle portion  306  of the removable contact member  230 , however alternate embodiments may be operative to engage and retain portions of the housing portion  304 . 
       FIG. 5  illustrates a top partially cut-away view of the exemplary embodiment. In this regard, the second switch  218  is shown in a closed state such that the removable contact member  230  is engaging the stationary contact portion  228 . The removable contact member  230  is engaging the retaining member  402 , and the front panel  212  is closed such that the front panel  212  obscures the cavity  210  and the contents of the cavity  210 . 
       FIG. 6  illustrates a top partially cut-away view of the exemplary embodiment where the second switch  218  is shown in an open state such that the removable contact member  230  is disengaged from the stationary contact portion  228  as a result of the opening of the front panel  212  by pivoting the front panel  212  about an axis of rotation  250  (illustrated in  FIG. 2 ). 
     Though the illustrated embodiment shows the front panel  212  pivoting about the axis of rotation  250 , alternate embodiments may include a front panel  212  that is connected to another portion of the switch box  202 . In this regard,  FIG. 7  illustrates an alternate exemplary embodiment that includes the front panel  212  pivoting about the axis of rotation  750  that is arranged substantially parallel to the longitudinal axis of the removable contact member  230 . 
     In an example of operation, an operator may open the first switch  214  by rotating the actuating lever  216  lever to place the first switch  214  into an open position or disconnected state. In some exemplary embodiments, the rotation of the actuating lever  216  may disengage the interlock assembly  226  to allow the movement or displacement of the front panel  212 . When the operator opens the front panel  212 , the force on the front panel  212  is operative to pull or disengage the removable contact member  230  from the stationary contact portion  228  thus placing the second switch  218  into an open position or disconnected state. The open states of the first switch  214  and the second switch  218  electrically isolate the fuses  224  from the system  100 . 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.