Abstract:
A modular fuse carrier provides an insulating housing of standard form factor incorporating adapter bus bars having multiple mounting points for different fuse brackets at different separations. The adapter bus bars may be attached to connectors and/or bus bars in fixed configurations to allow standardization and pre-manufacture of electrical assemblies that remain amenable to a wide variety of different fuse types and capacities.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
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     CROSS-REFERENCE TO RELATED APPLICATIONS 
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     BACKGROUND OF THE INVENTION 
     The present invention relates to high-power electrical systems and, in particular, to an adapter for high-power electrical fuses used in such systems. 
     High-power electrical fuses handling hundred of amperes at kilovoltages come in a variety of sizes and configurations including ANSI, DIN and British Standard types. These fuse types have different form factors, including different lengths, diameters, and mounting styles depending on both the type and power capacity required, meaning that fuse types and capacities are generally not interchangeable within an installation. While the different fuse types provide overlapping ranges of electrical functions, a customer will typically require a particular fuse type for reasons of standardization within a facility, availability, or electrical capacity requirements. 
     Fuses are typically used in conjunction with other common electrical elements, for example, electrical contactors, disconnect switches, and the like and assembled in standard configurations. Ideally such standard configurations could be pre-manufactured to avoid costly field assembly. Pre-manufacture of standard configurations can also provide for improved construction including, for example, the use of pre-formed bus bars instead of point-to-point wiring and the incorporation of the components into a standardized drawer assembly permitting the assembly to be readily withdrawn from an equipment cabinet for servicing (for example, for inspection or replacement of the fuses or contactor contacts). 
     Unfortunately, in order to allow the customer freedom in the choice of fuse type, a variety of different standard assemblies must be pre-manufactured or the installation of the fuses left to the field assembly by the customer. These choices defeat the purpose of pre-manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention provides a fuse carrier that converts a variety of different fuse types and sizes into a standard element that may be readily integrated in pre-wired or pre-manufactured assemblies. Generally, the invention provides for a rectangular housing that is readily integrated into an equipment drawer and which includes a range of mounting points that allows a variety of different fuse types and capacities to be held within the housing in a standard volume. By wiring the housing into place, the end user may, with relatively little effort and with no rewiring, freely select among a variety of different fuses and even change among different types and capacities after installation. 
     Specifically then, the present invention provides a modular fuse carrier having an electrically insulating housing providing a generally rectangular base having upstanding sidewalls and end walls defining, together with the base, a housing volume accessible through an open face opposite the base and having interior divider walls parallel to the sidewalls. The housing holds a set of six adapter bus bars mounted to the base and arranged in three rows separated by the divider walls and arranged along axes between end walls in two columns arranged along axes between sidewalls, the adapter bus bars electrically separated with individual adapter bus bars of each row positioned adjacent to opposite end walls of the housing. Outward, exposed surfaces of corresponding pairs of the adapter bus bars of each row extend along the row by an amount sufficient for the pairs to be spanned by a range of electrical cartridge fuses for voltages between 2.42 and 7.2 kV having different lengths corresponding to different current thresholds. Each adapter bus bar provides multiple mounting points corresponding to each of different electrical cartridge fuses of the range. The adapter bus bars of one column have connections adjacent to an end wall to power connectors extending through an end wall, and adapter bus bars of the other column have connections each to one of a set of three bus bars extending through the housing to an external connection point. 
     The current threshold range of fuses may be at least 100 amps to 800 amps and the mounting points may provide for the attachment of each of DIN-type, ANSI-type, and British Standard type fuse brackets. 
     It is thus one object of at least one embodiment of the invention to provide a fuse carrier module that may be pre-assembled into power units using preformed bus bar type conductors and yet accommodating a wide range of fuse types and capacities. 
     The adapter bus bars may be plates and the mounting points may be internally threaded holes open at the surface of the plates. 
     It is thus an object of at least one embodiment of the invention to provide a structure allowing maximum flexibility in fuse attachment and the ability to pre-populate multiple mounting points at low cost overhead. 
     The mounting points may receive fuse brackets selected from the group consisting of single fuse L-brackets, double fuse L-brackets, triple fuse L-brackets, and spring clips. 
     It is thus an object of at least one embodiment of the invention to permit both ANSI and DIN type fuses as well as parallel assemblies of ANSI and British Standard type fuses. 
     The three bus bars may extend to points proximate to an outside of one side wall for attachment to a contactor having a base wall coplanar with the base of the modular fuse carrier. 
     It is thus an object of at least one embodiment of the invention to provide an integrated connection system suitable for close integration with a standard contactor. 
     The module may further include a set of insulating barrier plates sized to fit between the rows and the end walls in lieu of or augmenting the divider walls, and may further include retaining elements releasably retaining the insulating barrier plates for use with ganged fuse configurations. The end walls may provide supports for four insulating barrier plates between each row and between a top and bottom row and the corresponding sidewall. 
     It is thus an object of at least one embodiment of the invention to maximize airflow and fuse accessibility when ganged fuses are not required. 
     The insulating barrier plates may provide central apertures allowing airflow through the fuses at the center of the fuses while providing barriers at electrically conductive portions of the fuses, and the sidewalls and divider walls may have corresponding apertures aligned with air vents passing through the base extending along the columns. 
     Thus it is an object of at least one embodiment of the invention to provide for a modular housing while retaining good airflow qualities that would be expected in non-modular construction where the fuses are mounted to a simple base plate or a custom fuse block. 
     The power connectors may be oriented to mate along axes parallel to and aligned with the rows. 
     It is thus an object of at least one embodiment of the invention to provide a modular fuse adapter that can be put on a rack and pulled from equipment for service using axially releasable connectors while providing access to the fuses perpendicular to the axis. 
     The housing may provide symmetrical mounting points on an end wall closest to the second column about a plane bisecting the end wall and parallel to the base. 
     It is thus an object of at least one embodiment of the invention to permit installation in a left or right hand orientation. 
     The end wall may include integrally molded insulating tubes receiving power connectors attached to adapter bus bars of the first column. 
     It is thus an object of at least one embodiment of the invention to provide for protective shrouding around the connectors as part of the housing limiting the need for separate shielding measures. 
     The adapter bus bars may be held by bolts received by threaded inserts in the insulating base. 
     It is thus an object of at least one embodiment of the invention to provide a simple method of providing multiple terminations within an insulating plastic housing. 
     The power connectors may be selected from the group consisting of tulip-style, bullet-style, and finger-style connectors. 
     It is thus another object of at least one embodiment of the invention to provide substantial flexibility in connector style. 
     These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of the housing of the present invention from a front side showing connector shrouds formed in an end wall of the housing; 
         FIG. 2  is an exploded view similar to that of  FIG. 1  showing ANSI-type fuses and their associated mounting brackets; 
         FIG. 3  is a detailed, exploded view of an adapter bus bar of the present invention showing different styles of fuse brackets received at different mounting points; 
         FIG. 4  is a front elevational view of the housing of the present invention showing two sizes of DIN-type fuses; 
         FIG. 5  is a rear perspective view of the housing of  FIG. 1  showing bus bar connections between the fuses and associated electrical components; and 
         FIG. 6  is a simplified representation of the housing of the present invention incorporated into an equipment drawer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , a modular fuse carrier  10  of the present invention provides for an electrically insulating, generally rectangular housing  12  having a substantially planar and rectangular base  14  surrounded by four upstanding and opposed walls including end walls  16  and  18  and sidewalls  20  and  22 . The walls  16 ,  18 ,  20  and  22  form a generally rectangular frame defining an interior volume of the modular fuse carrier  10  open from a front face  24 . 
     Referring also to  FIG. 2 , a set of two divider walls  26  extending from the base  14  generally parallel to the sidewalls  20  and  22  divide the interior volume into three rows along row axes  27  extending between the end walls  16  and  18 . Each of these rows may accept one or more fuses  30 . Although ANSI-type fuses  30  are shown, as will be described in more detail below, the present invention may accommodate any of the standard fuse configurations of DIN-type, ANSI-type fuse, and British Standard type mounts having ratings in the range of 2.4-2.7 kV and in the range of 100 to 400 amps and preferably 10 to 800 amps. 
     For this purpose, each row provides two conductive adapter bus bars  32   a  and  32   b  positioned at opposite ends of each row near walls  18  and  16  respectfully. Adapter bus bars  32   a  are thus positioned in a first column along a column axis  34  near wall  18  while adapter bus bars  32   b  are positioned in a second column along a column axis  34  near wall  16 . 
     As shown in  FIG. 3 , the adapter bus bars  32  include a base plate  36  held adjacent and parallel to the base  14  of the housing  12  and an outwardly extending flange  38  perpendicular thereto. The adapter bus bars  32   a  and  32   b  may be manufactured to be substantially identical and simply given different orientations depending on whether they are placed in the first or second column. In either, flange  38  is placed adjacent to a respective wall  18  or  16  and includes mounting holes  40  that may receive bolts  42  that may be used to attach the flange  38  to the shaft of an electrical power connector  44  (when in the first column) or the end of a bus bar  46  (when in the second column). 
     Referring still to  FIG. 3 , the base plate  36  includes mounting holes  45  that are used to attached the adapter bus bar  32  to the base  14  of the housing  12  by bolts  48  passing through the holes  45  into threaded inserts  50  held in insulated bores  53 , the latter molded into the base  14 . The upper surface of the base plate  36  also includes multiple mounting points  52 , in one embodiment, providing upwardly exposed threaded bores for receiving machine screws holding mounting brackets  54   a  or  54   b . The threaded bores of the mounting points  52  may be tapped holes directly in the base plate  36  or may be inserts such as well-known “PEMM studs” press fit or riveted to the base plate  36 . Alternatively, multiple adapter bus bars may be provided with different sets of holes placed at different mounting points on the surface and/or different PEMM studs. 
     Mounting bracket  54   a  provides an L-bracket having a bottom flange  56  that may attach to the mounting points  52  to provide electrical connection to the adapter bus bar  32  and an upwardly extending portion  57  having one to three in-line holes  58  aligned with the row axes  27  that may receive bolts  60  used to attach the ends of ANSI-type or British Standard-type fuses  30  thereto with the long dimension of the fuses  30  also extending along the axes  27 . The bracket  54   a  may be attached at a single set of mounting points  52  on the adapter bus bars  32  closest to an end wall  18  or  16  and thus a pair of brackets  54   a  accept fuses of a single standard fixed length along the row. On the other hand, different brackets  54   a  having different numbers of holes  58  may accommodate different numbers of parallel fuses  30  as ganged in a column along the extent of the upwardly extending portion  57 . 
     Referring still to  FIG. 3  and  FIG. 4 , alternatively the mounting bracket  54   b  may be used for attachment of DIN-type fuses to the adapter bus bar  32 . This mounting bracket  54   b  provides a spring clip element  64  for receiving a conductive ferule on the ends of the fuses  30 ′, the spring clip element  64  being attached to a base  66  that may be received by mounting points  52  in two different locations reflecting the two different lengths of DIN-type fuses  30 ′. The mounting bracket  54   b  includes a retaining clip  68  allowing the fuse  30 ′ to be locked in position. 
     In this way, the mounting conventions of DIN-type, ANSI-type fuse, and British Standard-type fuses may all be accommodated through the use of different mounting brackets  54   a  and  54   b  while different fuse capacities can be accommodated through movement of the mounting brackets&#39;  54  two different mounting points  52  to accommodate fuses  30 ′ of different length or through the use of L-brackets  54   a  allowing ganging of different numbers of fuses  30 . By providing simple mounting points  52  in the form of threaded holes, the adapter bus bars  32  may be pre-populated with mounting points  52  at relatively low expense to a customer who only wants one type of fuse  30 . 
     The modular fuse carrier  10  of the present invention may be shipped with a variety of different mounting brackets or mounting brackets may be selected with the understanding they may be replaced at a later date by simple removal of bolts. 
     Referring now to  FIGS. 1 ,  2 ,  4 , and  6 , end wall  18  may include integrally molded rectangular tube shrouds  70  surrounding the connectors  44  when the connectors  44  are attached to adapter bus bars  32   a  as described above. As so attached, the connectors  44  extend axially along the axes  27  to receive a mating connector  86  along the axes  27 . In this way, the entire housing  12  may be plugged in or unplugged by motion along the axes  27 . A variety of different connector types may be used, for example, well known tulip-style, bullet-style, and finger-style connectors. 
     Referring now to  FIGS. 5 ,  4 , and  6 , the adapter bus bars  32   b  may be connected to first ends  77  of the bus bars  46  by two bolts and  42  pass through the flange  38 . These bus bars  46  are preformed to pass through the base  14  after connection with the adapter bus bar  32   b , as covered with insulated sleeves  47 , and then to curve 90° to pass along the outside of the base  14  generally along the axes  27  and curve by 90° along the plane of the base  14  to side wall  22 , curving upward along the side wall  22  to terminate at second ends  78  that may be received by the terminals of an adjacent contactor  80 . 
     Referring still to  FIG. 6 , in this configuration the modular fuse carrier  10  and contactor  80  may be installed on a carriage  82  that provides a sliding drawer mechanism allowing the assembly of the modular fuse carrier  10  and contactor  80  to be withdrawn along an axis  27  generally aligned with the rows of the fuses so that the front face  24  of the modular fuse carrier  10  may be accessible for removal or installation of fuses  30 . The carriage  82  provides mounting rails (not shown) that may attach to aligned walls of the contactor  80  and the housing  12  and, in particular, which may use mounting points  97  on an end wall  16  of the housing  12 . 
     Electrical connections between the modular fuse carrier  10  and other equipment (not shown) within an equipment cabinet holding the carriage  82  may be realized through the connectors  44  of the modular fuse carrier  10  connecting with corresponding connectors  86  attached to an internal wall of the equipment cabinet. Similar connectors  88  may be provided on the carriage  82  for the contactor  80  which may mate with corresponding connectors  86 ′ also attached to the internal wall of the equipment cabinet. 
     The present invention, by providing a standard form factor for a range of different fuses  30 ,  30 ′, allows the wiring between various elements (for example the contactor  80 ) to be realized with bus bars  46  that are shaped using equipment not readily accessible in the field. 
     Referring now to  FIGS. 2 and 6 , as noted, the end wall  16  provides mounting points  92  which are symmetrically opposed about a plane bisecting the end walls  16  and parallel to the base  14  to allow the modular fuse carrier  10  to be rotated 180° about an axis parallel to axes  27  to provide a system that is accessible from the left side rather than the right side. 
     Referring now to  FIGS. 2 and 5 , the present invention also contemplates the provision of replaceable interphase barriers  96  that may serve as the divider walls  26  (previously described) or that may be slid in place next to divider walls  26  by means of channels  98  on interposed end walls  16  and  18  as shown in  FIG. 2 . These interphase barriers  96  increase the height of the divider walls  26  when three ganged fuses  30  are used. The interphase barriers may be retained by spring clip  106 . 
     Each of the divider walls  26 , sidewalls  20  and  22 , and interphase barriers  96  include a central notch aperture  100  exposing a mid-portion of the fuses  30  or  30 ′ to allow unobstructed airflow vertically through these apertures  100  where electrical arc protection is not required. These apertures  100  aligned with vents  102  cut in the base  14  extending along a column between the adapter bus bars  32   a  and  32   b  so as not to be obstructed thereby. 
     The housing  12  and interphase barriers  96  may be made of fiber reinforced plastics such as a glass filled polymer (e.g. Glastic). The housing  12  may be molded as a single piece using injection molding or as separate pieces molded and assembled, for example, with the base  14  and walls  16  and sidewalls  20  and  22  integrally molded and the end wall  18  with the shrouds  70  molded separately and epoxy bonded thereto. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.