Abstract:
A connection apparatus includes a housing portion comprising a back panel and side panels, 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, a fuse holder assembly disposed in the cavity, and a cover disposed in the cavity between a portion of the fuse holder assembly and the entry area to the access orifice, the cover obscures a portion of the fuse holder assembly.

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. 
     The electrical connection between the fuses and components that may be connected to the fuses may result in a “back feeding” state where a voltage may be present at the fuse even if the fuse is partially isolated from the system with a switch. Thus, prior to accessing the fuse during installation, maintenance, or troubleshooting, a technician should determine whether a voltage is present at the fuse. If a voltage is present at the fuse, the technician should not access the fuse until the source of the voltage is isolated from the fuse. 
     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 prior to accessing the fuse. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention a connection apparatus includes a housing portion comprising a back panel and side panels, 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, a fuse holder assembly disposed in the cavity, and a cover disposed in the cavity between a portion of the fuse holder assembly and the entry area to the access orifice, the cover obscures a portion of the fuse holder assembly. 
     According to another aspect of the invention, a switch apparatus includes a housing portion comprising a back panel and side panels, the back panel and side panels partially defining a cavity and an access orifice, a switch disposed in the cavity, a fuse holder assembly disposed in the cavity, the fuse holder assembly electrically connected to the switch, and a cover disposed in the cavity between a portion of the fuse holder assembly and the access orifice, the cover obscures a portion of the fuse holder assembly. 
     According to yet another aspect of the invention, a cover includes a front cover panel portion including a non-conductive material, a first side cover panel portion connected to the front cover panel portion and arranged substantially perpendicular to the front cover panel portion, a second side cover panel portion connected to the front cover panel portion and arranged substantially perpendicular to the front cover panel portion, a first extension portion connected to the first side cover panel portion and arranged substantially parallel to the front cover panel portion, a second extension portion connected to the second side cover panel portion and arranged substantially parallel to the front cover panel portion, and a probe orifice arranged in the front cover panel portion. 
     According to yet another aspect of the invention, a system includes a power source, and a connection apparatus comprising a housing portion comprising a back panel and side panels, 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, a fuse holder assembly disposed in the cavity, the fuse holder assembly electrically connected to the power source, and a cover disposed in the cavity between a portion of the fuse holder assembly and the entry area to the access orifice, the cover obscures a portion of the fuse holder assembly. 
     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 a perspective view of an exemplary embodiment of the cover of  FIG. 2 . 
         FIG. 4  illustrates a front view of the exemplary embodiment of the cover of  FIG. 3 . 
         FIG. 5  illustrates a top partially cut-away view of the cover along the line  5  of  FIG. 2 . 
         FIG. 6  illustrates another top partially cut-away view of the cover along the line  5  of  FIG. 2 . 
         FIG. 7  illustrates a top view of the cover along the line  5  of  FIG. 2 . 
         FIG. 8  illustrates a front view of the switch box with the cover arranged in a closed position, in accordance with an embodiment of the invention. 
         FIG. 9  illustrates a front view of the switch box with the cover arranged in an open position, 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 a load  110  and an AC grid  112 . While the electrical 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 switch  114  that is electrically connected to the fuse  116  and the DC power source  102 . The arrangement of the switch  114  allows the fuse  116  to be electrically isolated from the DC power source  102  when the switch  114  is in an open position or state. 
     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). Thus, prior to accessing the fuse  116  during installation, maintenance, or troubleshooting, a technician should determine whether a voltage is present at the fuse  116 . If a voltage is present at the fuse, the technician should not access the fuse  116  until the source of the voltage is isolated from the fuse. 
     The embodiments described below include an obstructive member between the fuse  116  and an access opening of the switch box  104  that will allow a technician to test the fuse  116  to determine whether voltage is present while the obstructive member remains in position. In operation, once the technician has tested the fuse  116  and ensured that no voltage is present at the fuse  116 , the technician may remove or reposition the obstructive member to gain physical access to the fuse  116 . 
     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 in an embodiment 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  are arranged in the cavity  210 . The switches  214  are connected to an actuating lever  216  with a mechanical linkage arrangement such that the movement of the actuating lever  216  changes the position or state of the switches  214 . Each of the switches  214  includes a terminal that may be connected to an electrical cable or line. The switches  214  are electrically connected to corresponding fuse holder assemblies  219 . The 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 may be electrically connected to an electrical cable or line. 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 , and terminals of the second fuse holder portion  222 . 
     As discussed above, in operation, a voltage may be present in the fuses  224  and the fuse holder assemblies  219  during a back feeding state even if the switches  214  are in an open position or state. It is desirable to encourage a technician to determine whether a voltage is present in the fuses  224  and the fuse holder assemblies  219  prior to performing installation, maintenance, or troubleshooting tasks.  FIG. 2  illustrates a partially transparent view of an exemplary embodiment of a cover  225  that is arranged in the cavity  210  between the access orifice  211  and the second fuse holder portions  222 . In the illustrated embodiment, the cover  225  is fabricated from a non-conductive or insulating material such as, for example, a plastic, nylon, composite, or other type of non-conductive material. The cover  225  of the illustrated embodiment is fabricated from a single sheet of semi-rigid material however, alternate embodiments are not limited to being fabricated from a single sheet of material, and may be fabricated and assembled from any number or combination of parts and components that many include, for example, rigid, flexible, or semi-rigid materials. 
       FIG. 3  illustrates a perspective view of an exemplary embodiment of the cover  225 . The cover  225  includes a front cover panel portion  302  and side cover panel portions  304  that are connected to the front cover panel portion  302 . The side cover panel portions  304  are connected to extension portions  306 . In the illustrated embodiment, the extension portions  306  include at least one orifice  308  that is operative to receive a fastener such as, for example, a bolt or a screw (not shown). The front cover panel portion  302  includes probe orifices  311  that are sized and shaped to allow a voltage or other type of testing probe to be inserted through the probe orifices  311 . The probe orifices  311  of the illustrated embodiment are formed in a circular shape and are sized such that a testing probe may pass through one of the probe orifices  311 , but other tools that are larger than the diameter of the probe orifices  311  or parts of a human body such as, a finger may not pass through the probe orifices  311 . Thus, the front cover panel portion  302  partially obscures portions of the fuse holder assemblies  219  when viewed by a technician via the access orifice  211  (of  FIG. 2 ).  FIG. 4  illustrates a front view of the exemplary embodiment of the cover  225  of  FIG. 3  as described above. 
       FIG. 5  illustrates a top partially cut-away view of the cover  225  along the line  5  (of  FIG. 2 ). The cover  225  is secured to the rear panel  206  of the switch box  202  with fasteners  504  and  505  that pass through the orifices  308  (of  FIG. 3 ). The fasteners  504  and  505  may be similar or dissimilar. In one embodiment, the fastener  505  includes a “one-way” screw head that makes removal of the fastener  505  difficult without special tools, while the fastener  504  includes a traditional screw head such as, for example, a slotted screw head. Thus, a technician is discouraged from removing the fastener  505  and is encouraged to remove the fastener  504 . Such an arrangement helps to ensure that the cover  225  may not be completely removed by a technician and discarded. The probe orifices  311  are arranged to align with corresponding test contact points  502  on the second fuse holder portions  222  such that each of the probe orifices  311  and the corresponding test contact points  502  define lines substantially normal to the front cover panel portion. The test contact points  502  are electrically connected to the fuses  214  and the terminals of the second fuse holder portions  222 . The test contact points  502  may include any conductive portion of the second fuse holder portions  222  that are electrically connected to the terminals of the second fuse holder portions  222 . The front cover panel portion  302  is arranged such that the planar surfaces of the front cover panel portion  302  are substantially parallel to the planar surfaces of the rear panel  206 . In the illustrated embodiment, the planar surfaces of the side cover panel portions  304  are substantially perpendicular to the planar surfaces of the front cover panel portion  302  and the planar surfaces of the extension portions  306  are substantially parallel to the rear panel  206 . In alternate embodiments, the planar surfaces of the cover  225  may be arranged in any suitable alternative arrangement relative to each other, or the switch box  202 , and are not limited to the arrangements described above. The line  501  illustrates a plane partially defined by the by exposed edges  217  of the side panels  218  (of  FIG. 2 ), the cover  225  is disposed between the plane partially defined by the by exposed edges  217  of the side panels  218  and the second fuse holder portions  222 . 
       FIG. 6  illustrates another top partially cut-away view of the cover  225  along the line  5  (of  FIG. 2 ).  FIG. 6  illustrates the use of a test probe  602  that is electrically connected to a test device  604 , such as, for example, a voltmeter device. The test probe  602  is shown passing through a probe orifice  311  of the cover  225  to contact a corresponding test contact point  502  of the second fuse holder portions  222 . The diameter (d) of the probe orifice  311  is between about 2.5 mm to 4 mm and greater than the diameter (d′) of the test probe  602  such that the test probe  602  may pass through the probe orifice  311 .  FIG. 6  also illustrates a finger  606  that has been placed adjacent to a probe orifice  311 , the diameter (d) is less than the approximate diameter (d″) of the finger  606 , thus preventing the finger  606  or other objects from passing through the probe orifice  311  and contacting conductive portions of the second fuse holder portions  222 . 
       FIG. 7  illustrates a top view of the cover  225  along the line  5  (of  FIG. 2 ). In  FIG. 7 , the fastener  504  (of  FIG. 5 ) has been removed, and the cover  225  has been moved to provide access to the second fuse holder portions  222  and the fuses  224 . In the illustrated embodiment, the cover  225  has been deformed to flex about the region  702 . The region  702  of the cover  225  may include a crease or scored portion to reduce the resistance to the deformation. The fastener  505  secures the extension portion  306  of the cover  225  to the rear panel  206  of the switch box  202 . 
       FIG. 8  illustrates a front view of the switch box  202  with the cover  225  arranged in a closed position. The cover  225  obscures portions of the second fuse holder portions  222  (of  FIG. 2 ) and the fuses  224 . The cover  225  is secured to the rear panel  206  of the switch box  202  with the fasteners  504  and  505 , however any number of fasteners or other fastening means such as, for example, clips, pins, brackets or tabs may be used in alternate embodiments. 
       FIG. 9  illustrates a front view of the switch box  202  with the cover  225  arranged in an open position. The fastener  504  has been removed, and the cover  225  has been positioned to expose and to allow access to the second fuse holder portions  222  and the fuses  224 . 
     Though the embodiments of the switch box  202  (of  FIG. 2 ) include switches  214 , in alternate embodiments the switch box  202  may be a connection box that does not include the switches  214 , but includes the fuse holder assemblies  219  and the cover  225  arranged in a similar manner as discussed above. 
     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.