Abstract:
A fuse state indicator for a cascading fuse multiple discharge device including a fiber optic cable having a first end, a second end, and an intermediate segment. The intermediate segment is configured for attachment to a fuse assembly of a fuse panel where the fuse panel is arranged for physically severing the intermediate segment of the fiber optic cable in response to discharge of the fuse assembly.

Description:
[0001]    This invention was made with Government support under U.S. Government Contract W911QX-08-C-0077, awarded by U.S. Army Contracting Command. The government has certain rights in the invention. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to indicators for fuse designs. More particularly, the present invention relates to indictors for remotely monitoring the operational status of individual fuse assemblies in multiple discharge device fuse panels having cascading switch designs. 
       BACKGROUND OF THE INVENTION 
       [0003]    In recent years, there has been considerable improvement in the area of pulsed power research, which involves the storing, shaping, and performance of high energy density capacitors used in pulsed power applications. These pulsed power applications may require extremely high discharges of voltage and current. For example, discharges of high voltages in the 10 kV or more range and high current in the 150 kA or more range have been proposed. Historically, high-energy electrical devices for pulsed power applications have been limited to a single discharge. Any subsequent discharges would require a time-intensive rebuilding and replacement of components before a second high energy discharge could take place. Repeatability of high energy discharges in the high power range in a short amount of time has been considered difficult or impossible to achieve based upon the extreme environment created by such discharges. 
         [0004]    Not only are new designs needed for multiple large pulses of power in a short time period, but further secondary challenges presented by possible design solutions also must be overcome. One such challenge is how to effectively monitor the components utilized to provide these discharges, especially if certain components, such as fuses, limit the number of discharges the device can provide before replacement is needed. 
         [0005]    Specifically, if a cascading fuse and switch design were to be used, how to monitor the operational status of the fuses or switches utilized would be problematic. Such monitoring is important to ensure that fuses are functional and fully intact given the extreme environment that electronics in such a device might be faced. Further, remotely monitoring the device is desired in order to provide an operator a safe environment, especially if the discharge device is in a difficult to access location. Accordingly, a sensor or indicator in such a device is needed which would not be damaged by large pulses of power and would not cause an operator to be subjected to high voltage when investigating the status of the internal fuses and switches. 
         [0006]    Therefore, what is needed is an indicator for a switch and fuse device which overcomes deficiencies of the past, and which enables effective monitoring of fuses or switches that protect electronics from multiple, high-voltage, high-current discharges of pulsed power. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention overcomes the problems of the prior art by providing a device, system, and method for indicating the operational status of the various fuse assemblies of a cascading switch located on a multiple discharge device. More specifically, remote monitoring of fuse assemblies is accomplished through use of specially designed fiber optic indicators which are not harmed or compromised by large amounts of pulsed power due to the advantageous design and dielectric properties of fiber optic components. 
         [0008]    In one embodiment, a fuse state indicator for a cascading fuse panel includes a fiber optic cable having a first end, a second end, and an intermediate segment. Further, the intermediate segment is configured for attachment to a fuse assembly of a fuse panel where the fuse panel is arranged for physically severing the intermediate segment of the fiber optic cable in response to discharge of the fuse assembly. 
         [0009]    In another embodiment according to the present invention, a fuse indicator system for a fuse panel is disclosed including a multiple-discharge fuse panel and a plurality of fiber optic cables. The fuse panel includes a plurality of cascading, single use fuse assemblies each containing a perforated plate portion arranged for movement upon discharge. Further, the plurality of fiber optic cables each have a cable associated with a specific one of the fuse assemblies. Each cable includes a first end, a second end, and an intermediate segment, where the intermediate segment is located adjacent the plate portion of the fuse assembly and is arranged to be severed in response to movement of the plate portion. This severed arrangement prevents light transmission from the first end of the fiber optic cable to the second end of the fiber optic cable to indicate fuse assembly use. 
         [0010]    According to an embodiment of the present invention, a method is provided for relaying information related to the operational status of a fuse assembly present in a cascading switch of a panel assembly. The method includes applying a light source to a first end of a gang of fiber optic cables, the individual cables each having an intermediate segment coupled adjacent a different fuse assembly and a second end spaced apart from the second ends of the other cables. The method further includes viewing the second ends of the cables to observe which cables transmit light from the first end. 
         [0011]    In another embodiment according to the present invention, a method is provided for determining when to replace a cascading fuse panel. The method includes providing fiber optic cables and housings that each hold a “U” shaped segment of cables for mounting adjacent fuse assemblies on a cascading fuse panel. The method also includes providing instructions for checking the operational status of the fuse assemblies, including, applying a light source to one end of the fiber optic cables and observing which fiber optic cables transmit light to an opposite end. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
           [0013]      FIG. 1  illustrates generally a perspective view of a multiple discharge device and fuse state indicators according to an embodiment of the invention. 
           [0014]      FIG. 2  illustrates generally some fuse state indicator components and a multiple discharge device according to an embodiment of the invention. 
           [0015]      FIG. 3  illustrates generally an exploded view of some fuse state indicator components and a multiple discharge device according to an embodiment of the invention. 
           [0016]      FIG. 4  illustrates generally a partial front perspective view of two fuse assemblies of a multiple discharge device equipped with fuse state indicators according to an embodiment of the invention. 
           [0017]      FIG. 5  illustrates generally a perspective view of a fuse assembly of a multiple discharge device equipped with a fuse state indicator according to an embodiment of the invention. 
           [0018]      FIG. 6  illustrates generally a perspective view of a fuse assembly of a multiple discharge device and a fuse state indicator prior to fuse discharge according to an embodiment of the invention. 
           [0019]      FIG. 7  illustrates generally a perspective view of a fuse assembly of a multiple discharge device and a fuse state indicator after fuse discharge where the resistor of the fuse assembly has exploded according to an embodiment of the invention. 
           [0020]      FIG. 8  illustrates generally a perspective view of an indicator block containing the ends of the fiber optic cables according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    The invention may be embodied in other specific forms without departing from the essential attributes thereof, therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive. 
         [0022]    In  FIGS. 1-8 , embodiments are disclosed of apparatus, methods, and systems related to fuse state indicators  10  for a multiple discharge device or fuse panel  100  having a cascading switch and fuse design. Fuse status indicators and systems implementing such indicators are disclosed for fuse panels  100  incorporating a plurality of cascading, single discharge fuse assemblies  110 . Multiple discharge devices refer to any housing component for multiple fuses which is used to protect electronics and is not limited to any particular shape of pulsed power application. In general, fuse indicators  10  are disclosed which include a fiber optic cable  20 , having a first end  30 , a second end  40  and an intermediate segment  50 . The intermediate segment  50  being further held in place by a fiber optic loop holder  60  adapted for mounting adjacent a fuse assembly  110  of a multiple discharge device  100 . Further, the type of multiple discharge devices  100  utilizing these fuse status indicators  10  are designed to respond to use of the individual fuse assemblies  110  with physical movement of a portion of the panel associated with the respective fuse assembly  110  that has been discharged. The fuse status indicators  10  accordingly use fiber optic cables  20 , and the capability of these cables  20  to transmit light to determine if individual fuse assemblies  110  have been used. Both the arrangement provided as well as the dielectric properties of fiber optic material allows the indicator to be largely unaffected by large pulses of power. 
         [0023]    Accordingly, testing whether the fuse assemblies  110  have been used simply requires a light source  62  (not shown), such as a flashlight, to be exposed to a first end  30  of a fiber optic cable  20 . If the fuse assembly  110  adjacent the intermediate section  50  of the fiber optic cable  20  has not been used, light will be transmitted to the second end  40  of the cable  20 . If the fuse assembly  110  has been used, the intermediate segment  50  of the cable  20  will be in a severed state and no light will be transmitted to a second end  40  of that cable  20 . Based on this arrangement, operation of one or more fuse indicators  10  is made possible. For purposes of describing the state of the fuse assemblies  110 , a fuse assembly  110  will be considered “used” and the fuse “discharged” when the resistor contained in the assembly has exploded due to a large pulse of power. 
         [0024]      FIGS. 1-3  disclose an example of a fuse panel  100  for use with fuse state indicators  10 . Specifically, fuse state indicators  10  are mounted in or partially mounted in the multiple discharge device  100  shown.  FIGS. 1 and 2  show a multiple discharge device  100  with fuse state indicators  10  in an assembled and partially assembled configuration and  FIG. 3  shows an exploded view of the panel  100  together with fuse state indicator components. For purposes of this application, the fiber optic cables  20  have been removed from  FIGS. 2 and 3  to provide greater clarity of the surrounding multiple discharge device components. The multiple discharge device  100  depicted is a generally an elongate structure largely comprised of multiple elongate conductive plates and non-conductive housing panels of material stacked in adjacent side-by-side relation to one another. Further, arranged as a part of the panel  100  are a plurality of spaced-apart fuse assemblies  110  which utilize a combination of resistors  112 , perforated plate portions  114  (also referred to at times as perforated panels  114 ) and spear shaped contacts  116 . These fuse assemblies  110 , taken in combination, cooperate to form a cascading switch and fuse design. In this particular embodiment, four fuse assemblies  110  are present. Mounted adjacent to each of these fuse assemblies  110  are the components of fuse state indicators  10 . In general, the fuse state indicators  10  are used to determine whether the adjacent fuse assembly  110  is available for use or whether its fuse has been used up and its functionality is likely in an altered or diminished state. The fiber optic cables  20  extending away from each of the fuse assemblies  110  are supported by various cable brackets  117  mounted in the panel  100 . The four fuse assemblies  110  have been labeled  110   a ,  110   b ,  110   c , and  110   d  in some of the figures and description for convenience of reference. Components associated with one of these particular fuse assemblies, likewise, may be labeled with reference numerals ending in “a”, “b”, “c”, and “d”, to indicate the fuse assembly  110  they are respectfully associated with. 
         [0025]    The multiple discharge device  100  generally is a part of a larger pulse power system which sends out very large power pulses through this panel  100 . For example, discharge of voltages in the 10 kV or more range and current in the 150 kA or more range are possible. The fuse assemblies  110  provided in this panel  100  function to both allow discharges of an entire power supply as well as to provide an energy pulse delay device. The fuse assemblies  110  are single use components in the sense that they only provide protection from a single large discharge of pulsed power. Small amounts of power that can readily pass across the fuse assembly and which are not detrimental to the resistors  112  are not considered to be such a use nor is the reconfigured circuit using components of the assembly after resister explosion considered a use. When fuse assemblies  110  are subjected to a large pulse of power, a resistor  112  mounted within a cavity of the panel  100  explodes and a perforated plate portion  114  is flung open. This plate portion can be perforated in various ways. The perforated plate portions  114  shown in  FIGS. 1-7  are perforated such that two sections are present, namely, an upper section  119  and a lower section  121 . They are divided by a nearly continuous slot which is horizontally disposed on the sides  123  and which is disposed in a semicircular fashion near the center  125  of the plate. Additionally, parallel to the top and bottom of the opening for the fuse assembly are additional partial horizontally disposed slots  127 . Based on these perforations, the panels will generally fold open into two segments when subjected to a force such as an explosion of the resistor  112 . This explosion results in the lower section  119  of the perforated panel  114  engaging a set of electrical contacts to complete the circuit with the next fuse assembly  110  in the cascading circuit. Further, the explosion and temporary disconnection of the first fuse assembly  110  provides the necessary delay needed in the system to dissipate the pulse. 
         [0026]    The explosion and the flinging open of a perforated plate portion  114  also provides the moving parts that make the fuse state indicators  10  described herein possible. An intermediate segment  50  of a length of fiber optic cable  20  is coupled adjacent each of the fuse assemblies  110  with both ends of the cable  30  and  40  located at remote locations from the fuse assembly  110 . Further, the intermediate segment  50  extends in the anticipated path of the perforated plate portion  114  when it is flung open into a folded disposition. Accordingly, the portions  114  will sever the intermediate segment  50  of the fiber optic cable  20  following an explosion of its resistor  112 . 
         [0027]    Consequently, the fiber optic cable  20  can convey to an operator whether the associated fuse assembly  110  has been used based on simply shining a flashlight, or other light source, on a first end  30  of the fiber optic cable  20  and observing whether the light is being transmitted to the second end  40  of the fiber optic cable  20 . If the cable  20  transmits light, then the fuse assembly  110  is not used and is still available for use. If the cable  20  does not transmit light, then the associated fuse assembly  110  has been used and can no longer be used to protect against a large discharge pulse. While use of one or more fuse assemblies  110  may not require replacement of the entire panel  100 , if all or many of the fuses are no longer available, replacement of the fuse panel  100  may be desired. By having a different fiber optic cable  20  associated with each individual fuse assembly  110 , an operator can quickly check each of the fuse assemblies  110   a ,  110   b ,  110   c , and  110   d  to determine if a replacement panel  100  is needed. As these types of high energy discharge panels  100  are frequently buried deep inside a discharge device and are sometime not accessible without destroying the entire discharge device, it can be very important to know how many and which fuse assembly switches are still operable so that replacement can be done at an appropriate time. 
         [0028]      FIGS. 4 and 5  provide detailed views of various fuse assemblies  110  mounted into portions of multiple discharge device  100  and the location of fuse indicators  10 . Specifically, the fiber optic loop holders  60  are incorporated into recesses  64  adjacent the opening provided by each of the fuse assemblies  110 . The fiber optic loop holders  60  are generally small box shaped housings having an “L” shaped cross section and a first face  66  that is mounted parallel to the face of the panel  100  and a second face  68  mounted parallel to the inner wall of passageways in the fuse assemblies  110 . A single continuous cable  20  extends from a first end  30  into the front face  66  of the fiber optic loop holder  60  in an aperture  70  shared by a fastener  72 . The cable  20  extends out a side aperture  74  in the face  68  of the loop holder  60  into a passageway formed by the fuse assembly  110  and back into another aperture  76  in the loop holder  60  such that the intermediate segment  50  of the cable is disposed in a “U” shaped configuration. The cable  20  then exits out the aperture  70  shared by fastener  72  and extends back to the second end  40  of the cable. The portions of the cable  20  entering and exiting the face  66  of the loop holder  60  contain an outer protective sheath covering the optical fibers of the fiber optic cable. The “U” shaped intermediate segment  50  of the cable does not contain a sheath. The unsheathed fiber optic cable is sufficiently rigid that a rapid movement by the perforated plate portion  114  will readily sever the “U” shaped loop. 
         [0029]    Operation of the fuse state indicators  10  can be better understood from  FIGS. 6-8 . First,  FIG. 6  shows a perspective view of a fuse assembly  110  of the EPS panel  100  equipped with a fuse state indicator  10  prior to use and explosion of the resistor  112  of the fuse assembly. As seen here, the unsheathed intermediate segment  50  of the cable  20  resides in the fuse assembly  110  in a continuous “U” shaped loop. The perforated plate portions  112  are located behind the intermediate segment  50  in a parallel flat arrangement. Although, not shown in  FIG. 6 , a resistor  112  is connected in circuit directly behind the perforated plate portions  112  within a cavity in the panel  100 . When that circuit is subjected to a large pulse of power, the resistor  112  explodes and the perforated plate portions  112  are flung open. More specifically, the portions  114  are folded up against the top and bottom walls of the fuse assembly passageway, as shown in  FIG. 7 . 
         [0030]      FIG. 7  depicts the fuse assembly  110  and fuse state indicator  10  of  FIG. 6  after use where the resistor  112  of the fuse assembly  110  has exploded. In this state, the “U” shaped loop of the intermediate segment  50  has been sheared off due to the forceful movement of the perforated plate portions  114 . At this point, because the cable  20  is no longer continuous, light will no longer be able to be transmitted from a first end of the cable  30  to a second end of the cable  40 . The “U” shaped configuration generally provides portions of cable  20  that are aligned in a parallel fashion which helps to ensure that the remaining sheared fiber ends are not only severed, but also not aligned with each other. 
         [0031]    Next, in  FIG. 8  an indicator block  80  is shown which houses the ends of fiber optic cables  20  for the fuse state indicators  10 . This indicator block  80  serves as the interface of an operator who is located remotely from the fuse assemblies  110  of the fuse panel  100  for determining the status of each of the four fuse assemblies  110   a ,  110   b ,  110   c , and  110   d  of the panel. Shown on the right side of  FIG. 8  is a round gang of four cables  20 . The ends of these four cables represent the first ends  30   a ,  30   b ,  30   c  and  30   d  of their respective cables  20 . Therefore, there is one cable  20  for each of the four fuse assemblies  110  of the panel. On the left side of the indicator block  80  are four in-line fiber optic cables representing the second ends  40   a ,  40   b ,  40   c , and  40   d  of the four fuse assemblies  110 . 
         [0032]    Accordingly, indicator block  80  allows an operator to check the state of the fuse assemblies  110  by shining a flashlight into the ends of the round gang of four cables  20  located on the right side of  FIG. 7  while looking at the ends  40  of the four in-line cables  20  located on the left side the figure. A light at one of the in-line, second ends  40   a - d  of the cable  20  indicates that the respective fuse assembly  110  associated with that specific cable is good (i.e. the perforated plate  114  has not sheared the fiber optic cable  20  during discharge). No light at the end of one of the cables  20  means that the fuse assembly  110  associated with that cable  20  has already been discharged. Accordingly, an operator can quickly review this indicator block  80  with nothing more than a flashlight to determine if which fuse assemblies  110  have been discharged. 
         [0033]    Although, one multiple discharge device design with cascading switches for protecting devices from large energy pulses is shown in  FIGS. 1-8 . Further discussion of the structure and operation of such a cascading switch and fuse design are set forth in the following as well as in copending patent application of Ser. No.______/______ by Doering et al., titled MULTIPLE DISCHARGE DEVICE CASCADING SWITCH AND FUSE DESIGN, which is hereby incorporated by reference in its entirety. 
         [0034]    For further reference, a more detailed discussion of the operation of an example of a multiple discharge device like the one in  FIGS. 1-8  is discussed in the following description. In general, in a multiple discharge device design with cascading fuse assemblies, the panel  100  has four large structural panel components, namely, a perimeter plate  120 , a first housing panel  122 , an interior plate  124 , and a second housing panel  126 , as seen in  FIG. 3 . When assembled, the plates and panels are combined and are generally disposed between a first major face  128  at side  130  of the panel  100  and a second major face  132  at side  134  of the panel  100 . In the embodiment shown, the plates and housing panels each have a radiused bend  136  and are accordingly stacked adjacent one another around this corresponding shape. A bended shape may be used in certain specific discharge devices, however, the shape is not critical to the function of the panel and accordingly, the panel  100  may be flat or otherwise shaped to appropriately suit a particular device or application. 
         [0035]    The perimeter plate  120  is generally made of metal or other conductive material and has a flat or radiused surface that corresponds to the adjacent first housing panel  122 . The perimeter plate  120  is largely one continuous plate that is largely isolated from interior plate  124 . Perimeter plate  120  includes connections leading to a plurality of resistors  112  at discrete spaced apart locations along the panel  100 . The plate  120  further has a plurality of apertures  138  that may be used with various connectors  139  for holding the plate  120  and the remainder of the panel  100  together. 
         [0036]    The first housing panel  122  is a structure having spaced-apart centrally disposed cavities  140  across its length. In the  FIGS. 1-7 , these cavities  140  are shown as apertures defined by cylindrical passageways extending from one primary face  141  to the opposite primary face  142  of the first housing panel  122 . The passageways provided by cavities  140  further have cylindrical depressions  143  that encircle the central passageway but do not extend all the way through the panel  122 . Resistors for the cascading circuit are located within these cavities  140 , where each cavity  140  contains a single resistor  112 . 
         [0037]    The interior plate  124  is a plate made of copper or other conductive material and has a flat or radiused surface similar to that of the perimeter plate  120 . At spaced-apart locations across the plate, portions of the plate are perforated such that perforated plate portions  114  are defined. These perforated plate portions  114  are formed at locations aligned with the cavities  140  of the adjacent first housing panel  122 . The perforated plate portions  114  define an upper flap portion which is largely rectangular but which contains a semicircular projecting tab extending from the lower edge and a lower flap portion of largely rectangular shape which contains a semicircular recess within the upper edge in mating relation to the projecting tab. The lower flap contains oval shaped apertures adjacent both sides of the semicircular recess. 
         [0038]    The second housing panel  126  is a further non-conductive housing structure of the panel that abuts against the interior plate  124  when the panel  100  is assembled. The second housing panel  126  contains spaced-apart, centrally disposed passageways  160  across the length of the second housing panel  126  with spacing similar to that of the cavities  140  that are disposed across the first housing panel  122 . The passageways  160  are shown as square passageways, although the possibility of passageways of other shapes and sizes is contemplated as well. The passageways  160  are aligned such that they correspond to the perforated panels of the interior plate  124 . Further, fuse status indicators  10  or other sensors may be located in the interior wall of passageways  160  adjacent the opening provided by these passageways. Such sensors may be used to measure one or more parameters related to the particular fuse assembly  110  or to indicate the operational status of the assembly  110 . 
         [0039]    The outward face of the second housing panel  126 , also referred to as the second major face  132  of the panel  100 , further contains a plurality contact plates  170  with spear-shaped contacts  116 . These plates  170  and contacts  116  may be separate components or integrally formed components. The spear shaped contacts  116  of the plates each project upwardly in a converging manner at each of the lower corners of the passageways  160 . The contacts  116  are aligned with, but spaced apart from the apertures  154  in the perforated plate portions  114  of the interior plate  124  when in the assembled state shown in  FIGS. 1 ,  2 , and  4 - 6 , for example. Projections of shapes other than spears as part of the contact plates  170  are possible. Likewise, coupling interactions other than those between spear shaped contacts and apertures, such as latches or other well-known coupling components are contemplated by this disclosure as well. 
         [0040]    Although in an open circuit configuration, the contact plate  170  of the fuse assembly  110  is also connected in circuit to a second resistor  112  within a cavity  140  before establishing a connection with perimeter plate  120 . This connection between the contact plate and the resistor  112  and perimeter plate  120  largely cannot be seen in the Figures, as it is made possible by wiring passing through an aperture in the body of the second panel housing  126 . 
         [0041]    Accordingly, the assembled panel  100  set forth in  FIGS. 1-8  can be understood to generally refer to a panel that is equipped with a plurality of fuse assemblies  110  that are connected in a cascading arrangement. The four fuse assemblies  110  shown in the figures have been labeled  110   a ,  110   b ,  110   c , and  110   d  in order of their cascading use. The corresponding components of each assembly may be referred to with a nomenclature of “a”, “b”, “c” or “d” denoting the fuse assembly each part is associated with for convenience as well. 
         [0042]    Prior to use of the panel, of the four fuse assemblies  110   a ,  110   b ,  110   c , and  110   d , only fuse assembly  110   a  and its resistor  112   a  provides a continuous connection between the power source and discharge device. Specifically, this provides a connection between the perimeter plate  120  and the interior plate  124  in the panel. The three remaining fuse assemblies  110   b ,  110   c , and  110   d  are not connected and the resistors  112   b ,  112   c , and  112   d  are initially in open circuit configuration. 
         [0043]    Operation of the panel  100  begins when a large pulse of power is experienced by the panel. First, the discharge device short circuits and current begins to flow through the first fuse assembly  110   a . As the current builds, the energy is enough to explode the resistor  112   a  in the first fuse assembly, essentially turning it into a fuse. The exact values of the exploding resistor being dependent upon the delay required. This explosion does two things. First, it provides the required delay in the pulse required by the multiple discharge device. Second, the pressure it creates causes the perforated plates  114   a  to deform along the preformed features, such that the lower flap  152  bends and causes apertures  154  to be forced down around and against the two spear shaped contacts  116   a  in a locked configuration. An example of this resulting configuration can be seen in  FIG. 7 , for example. The locking completes the circuit for the next fuse assembly  110   b  which is now continuous. Thereafter, when a subsequent large pulse of power is experienced by the discharge device, the process is repeated by fuse assembly  110   b  and the fuse assemblies  110   c  and  110   d  for subsequent pulses. 
         [0044]    The final fuse assembly  110   d  is slightly different, however, as it is the last fuse on the panel. Accordingly, the last fuse does not have spear shaped contacts for completing the circuit, but rather disconnects the circuit until the entire discharge device can be replaced. The location and arrangement of this last fuse assembly  110   d  can be seen in  FIG. 1 .  FIG. 1  generally depicts the assembled panel  100  from a slightly different front view. In this Figure, the fuse assembly  110   d  is shown oriented somewhat differently than the other assemblies. Namely, the perforated panels  114   d  are split vertically from top to bottom, rather than horizontally from side to side. Accordingly, when the resistor  112   d  explodes, the flaps of the perforated panels  114  will fold out against the sides of the passageway  160   d.    
         [0045]    Note that the resistors  112  used in this panel are general intended to be nominal resistors of the type typically used in electrical circuit designs of moderate power. Such moderate power is on a scale far less than the type of large pulses of power discussed in this application. In general, no specialized exploding components are necessary to carry out the explosions required for this design as the large pulses of power are enough to generate a reliable explosion when introduced to one of the resistors  112 . 
         [0046]    Accordingly, a cascading fuse and switch design is provided in this embodiment where four different pulses of power can be independently shielded by these fuses. Moreover, the cascading arrangement allows each subsequent fuse to be available within seconds of use of the previous fuse. 
         [0047]    The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the claims. Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. 
         [0048]    Various modifications to the invention may be apparent to one of skill in the art upon reading this disclosure. For example, persons of ordinary skill in the relevant art will recognize that the various features described for the different embodiments of the invention can be suitably combined, un-combined, and re-combined with other features, alone, or in different combinations, within the spirit of the invention. Likewise, the various features described above should all be regarded as example embodiments, rather than limitations to the scope or spirit of the invention. Therefore, the above is not contemplated to limit the scope of the present invention. 
         [0049]    For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of Section 112, sixth paragraph of 35 U.S.C. are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.