Abstract:
A support system for an electrical device arranges the plurality of heat-sink assemblies in an orientation that allows the forces associated with an electrical fault that are transferred to the support structure to be reduced. The arrangement allows the electrical fault forces to cancel one another out such that the resulting net force applied to the support structure is significantly reduced. The size, strength and/or robustness of the support system can be reduced as the forces transmitted thereto are greatly reduced. The heat-sink assemblies can be arranged to facilitate ease of maintenance by allowing the heat-sink assemblies to be removed from a front access panel of the electrical device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/042,493, filed on Apr. 4, 2008. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to fault-force supports and, more particularly, to a heat-sink brace for fault-force support. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    Electrical components, such as three-phase static switches, may be subject to electrical faults and the forces associated therewith. The fault forces can be in a range of about 4,000 to about 5,000 pounds of force at 100 kAIC. To contain these forces, support braces can be utilized that can withstand those forces. The typical static switches can be disposed in a cabinet and bolted down and spaced apart from one another. For example, the heat sinks for the static switch can be bolted through insulation devices, without an ability to absorb the forces. As a result, significant structural supports are required. 
       SUMMARY 
       [0005]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0006]    A support system for an electrical device, such as a three-phase static switch by way of non-limiting example, arranges the plurality of heat-sink assemblies in an orientation that allows the forces associated with an electrical fault that are transferred to the support structure to be reduced. The arrangement can allow the electrical fault forces to at least partially cancel one another out such that the resulting net force applied to the support structure is significantly reduced. The heat-sink assemblies can be oriented such that two of the heat-sink assemblies produce a similar magnitude of force in a same direction, while the other heat-sink assembly produces a fault force about double that of the other heat-sink assemblies and directed toward the fault produced by the other heat-sink assemblies. As a result, the opposing forces can at least partially cancel one another out, thereby reducing the net force transferred to the support structure. The size, strength and/or robustness of the support system can be reduced as the forces transmitted thereto are greatly reduced. The heat-sink assemblies can be arranged to facilitate ease of maintenance by allowing the heat-sink assemblies to be removed from a front access panel of the electrical device. Simple pressure-applying devices can be utilized to apply a supporting force between these support members and the heat-sink assemblies. 
         [0007]    An electrical device with a support system according to the present teachings includes a pair of opposing frame members operable to supply a supporting force. Three heat-sink assemblies each include at least one heat sink and a rectifier puck in heat-transferring relation with the at least one heat sink. The heat-sink assemblies transfer heat from the pucks to a fluid flowing across the heat-sink assemblies. A plurality of insulation members separate the three heat-sink assemblies from one another and electrically isolate the three heat-sink assemblies from one another. Each one of the three heat-sink assemblies is associated with a different phase of a three-phase electric power supply. The framing members support the three heat-sink assemblies and the insulation members. During an electrical fault condition of the electrical device, a first one of the three heat-sink assemblies produces a first force of a first magnitude in a first direction, a second one of the three heat-sink assemblies produces a second force of a second magnitude in a second direction, and a third one of the three heat-sink assemblies produces a third force of a third magnitude in a third direction. At least two of the first, second and third forces at least partially cancel one another out, thereby reducing a total force caused by the fault condition that is transferred to the frame members. 
         [0008]    A method of supporting heat-sink assemblies in an electrical device and dissipating electrical fault forces therein according to the present teachings includes electrically isolating three heat-sink assemblies from one another with insulation members disposed between adjacent ones of the three heat-sink assemblies. The three-heat sink assemblies and insulation members are supported from opposing frame members. Different phases of a three-phase power supply are associated with each one of the three heat-sink assemblies. A first electrical fault force of a first magnitude generated by a first one of the three heat-sink assemblies is directed in a first direction. A second electrical fault force of a second magnitude generated by a second one of the three heat-sink assemblies is directed in a second direction. A third electrical fault force of a third magnitude generated by the third one of the three heat-sink assemblies is directed in a third direction. At least two of the fault forces are at least partially cancelled out by one another. 
         [0009]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0010]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0011]      FIG. 1  is a simplified cutaway perspective view of a first embodiment of a support system for heat sinks for supporting fault forces according to the present teachings; 
           [0012]      FIG. 2  is a simplified top plan view of the support system of  FIG. 1  for supporting fault forces according to the present teachings; 
           [0013]      FIG. 3  is a simplified schematic representation of the fault force cancellation with the support system of  FIGS. 1 and 2  according to the present teachings; 
           [0014]      FIG. 4  is a simplified front plan view of a second embodiment of a support system for heat sinks for supporting fault forces according to the present teachings; 
           [0015]      FIG. 5  is a simplified top plan view of the support system of  FIG. 4  for supporting fault forces according to the present teachings; 
           [0016]      FIG. 6  is a simplified cross-sectional view along line  6 - 6  of  FIG. 5 ; and 
           [0017]      FIG. 7  is a simplified schematic representation of the fault-force cancellation with the support system of  FIGS. 4 and 5  according to the present teachings. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features (e.g.,  20 ,  120 ,  220 , etc.). 
         [0019]    According to the present teachings, a static switch which can be easily serviced by service personnel is a multi-part assembly. The multi-part assembly of the static switch enables the ability to breakdown the static switch into small, manageable parts. Having small, manageable parts can facilitate the service of the static switch by service personnel. For example, a 4,000-amp static switch can be advantageously designed to require service personnel to not have to physically lift more than about 50 to about 70 pounds. Additionally, the static switch can maintain electrical insulation at a nominal level of 600 vac, by way of non-limiting example. 
         [0020]    Structural support systems according to the present teachings are generally indicated as  20  in  FIGS. 1 and 2  and as  120  in  FIGS. 4 and 5 . Support systems  20 ,  120  can provide fault-force bracing that can withstand forces of about 4,000 to about 5,000 lbs. of force at 100 kAIC. The support systems  20 ,  120  can absorb some of the fault forces and reduce the magnitude of the fault forces translated to the structural members. Support systems  20 ,  120  can also reduce, possibly to a negligible value, the force transferred to the electrical insulators or conductors utilized in the static switch. The support systems can maintain the ability to slide out components of the static switch, such as the heat-sink assemblies, through the front of a cabinet. This capability allows the static switch to be serviced through front access to the cabinet. The support systems may eliminate the need to have access to the rear or sides of the cabinet to service the static switch. 
         [0021]    Referring to  FIGS. 1 and 2 , a first embodiment of a support system  20  according to the present teachings is shown. Support system  20  includes a plurality of framing members  22 ,  24  that are on opposite sides of a three-phase static switch (parts of which are partially shown and indicated generally at  26 ). Static switch  26  can include three heat-sink assemblies  28 ,  30 ,  32  that each includes three heat sinks  50  which are each separated by a rectifier puck  34 . Rectifier puck  34  can take a variety of forms. By way of non-limiting example, rectifier puck  34  can be a silicon controlled rectifier (SCR) puck, such as those available from Powerex, Inc. of Youngwood, Pa. 
         [0022]    Pucks  34  are operable to translate thermal gains from the static switch components to the heat sinks  50  associated with heat-sink assembly  28 ,  30 ,  32  and allow air to be passed over the heat-sink assemblies  28 ,  30 ,  32  to remove the heat gain. Heat-sink assemblies  28 ,  30 ,  32  are electrically hot and require electrical insulation therebetween. For example, sheets of electrical insulation  36  can be disposed between each heat-sink assembly  28 ,  30 ,  32 . Insulation  36 , by way of non-limiting example, can be ¼-inch thick glastic. 
         [0023]    Heat-sink assemblies  28 ,  30 ,  32  and insulation  36  are disposed between framing members  22 ,  24 . The outer insulation sheets  36  include horizontally extending glides  38  that can vertically support heat sinks  50  of heat-sink assemblies  28 ,  32  adjacent framing members  22 ,  24 . The inner insulation sheets  36  can also include horizontally extending glides  40  that can provide vertical support for heat sinks  50  on either side. A jig or assembly fixture (not shown) can be utilized to initially position heat-sink assemblies  28 ,  30 ,  32  and insulation  36  between framing members  22 ,  24 . Framing members  22 ,  24  include a plurality of pressure-applying devices  42 ,  44  that apply slight pressure P inwardly from each framing member  22 ,  24  and hold heat sinks  28 ,  30 ,  32  in place. Pressure-applying devices  42 ,  44  apply enough pressure P to allow the assembly jig or fixture to be removed and maintain heat-sink assemblies  28 ,  30 ,  32  and insulation  36  secured between framing members  22 ,  24 . Additionally, pressure-applying devices  42 ,  44  supply enough holding force to hold the heat-sink assemblies  28 ,  30 ,  32  in place during a fault condition, as described below. 
         [0024]    Pressure-applying devices  42 ,  44  can take a variety of forms. For example, set screws in framing members  22 ,  24  can be used to apply pressure P from framing members  22 ,  24  through heat-sink assemblies  28 ,  30 ,  32  and the insulation  36  disposed therebetween and onto framing members  24 ,  22 . In an alternate configuration, a threaded rod (not shown) can be utilized as a pressure-applying device  42 ,  44 . Regardless of the form of pressure-applying devices  42 ,  44 , the use of such devices allows for easy removal and replacement of one or more of the heat-sink assemblies  28 ,  30 ,  32  in the event service is required. 
         [0025]    The support system  20 , according to the present teachings, can cancel some of the fault forces and thereby reduce the magnitude of the fault forces translated or transferred to the structural members, such as framing members  22 ,  24 . This is accomplished by arranging the heat-sink assemblies  28 ,  30 ,  32  such that the resulting forces F during a fault condition can cancel one another, thereby reducing the net force transferred to framing members  22 ,  24  and other components of static switch  26 . In the event of a fault condition, the three electrical phases can have their individual forces act in opposite directions such that a reduction in the overall force to be absorbed by framing members  22 ,  24  is reduced. For example, as shown in  FIG. 3 , two of the heat-sink assemblies, such as heat-sink assemblies  28 ,  30 , will have a fault force (F 1 ) directed in the same direction (to the right in the image depicted in  FIG. 3 ) while the other one of the heat-sink assemblies, such as heat-sink assembly  32 , will have twice as large a fault force (2×F 1 ) in the opposite direction (to the left in the image depicted in  FIG. 3 ). As a result, the sum of the forces theoretically can be zero. However, in actuality the forces may not sum to zero and, as a result, some of the forces will be transmitted to framing members  22 ,  24  through pressure-applying devices  42 ,  44 . 
         [0026]    As a result, cancellation of some of the forces associated with a fault condition can be realized and the force required to be sustained by a support system  20  reduced. Additionally, with this arrangement fault forces transferred to electrical insulators and/or conductors can be reduced and/or eliminated. Thus, the arrangement allows for the cancellation of forces associated with a fault condition such that the overall force experienced by support system  20  is reduced. 
         [0027]    Referring now to  FIGS. 4-6 , a preferred embodiment of a support system  120  according to the present teachings is shown. Support system  120  includes a plurality of framing members  122 ,  124  that are on opposite sides of a three-phase static switch (parts of which are partially shown and indicated generally at  126 ). Static switch  126  can include three heat-sink assemblies  128 ,  130 ,  132  that are arranged adjacent one another between framing members  122 ,  124  and separated by sheets of electrical insulation  136 . In this embodiment, each heat-sink assembly  128 ,  130 ,  132  includes a pair of heat sinks  150   a,    150   b  that are spaced apart with a pair of rectifier pucks  134  therebetween (best seen in  FIG. 6 ). Rectifier pucks  134  are spaced apart vertically from one another, as shown in  FIG. 6 . Each heat sink  150   a,    150   b  includes an end plate  152  and a plurality of heat-transferring fins  154  extending therefrom. End plate  152  and fins  154  are in heat-transferring relation with one another and with pucks  134 . Pucks  134  are disposed between end plates  152  of heat sinks  150   a,    150   b.    
         [0028]    Each heat-sink assembly  128 ,  130 ,  132  is held together with a pair of clamps  158  on opposite sides of each puck  134 . As shown, two pairs of clamps  158  are utilized to hold a heat-sink assembly together. It should be appreciated that additional clamps or less clamps can be used, as desired. Clamps  158  include a bar member  160  that extends through openings in opposing end plates  152  on opposite sides of pucks  134 . The ends of each bar member  160  can be threaded and can include nuts or similar fasteners  162  that allow the end plates  152  of adjacent heat sinks  150   a,    150   b  to be pulled toward one another such that bar member  160  is in tension. Clamps  158  can thereby retain heat sinks  150   a,    150   b  together with pucks  134  disposed therebetween, thereby forming a heat-sink assembly. Bar member  160  and fasteners  162  can be aluminum, by way of non-limiting example. 
         [0029]    Rectifier pucks  134  can take a variety of forms. By way of non-limiting example, rectifier pucks  134  can be a silicone controlled rectifier (SCR) puck, such as those available from Powerex, Inc. of Youngwood, Pa. Pucks  134  are operable to translate thermal gains from components of static switch  126  to the associated heat-sink assemblies  128 ,  130 ,  132  and allow air to be passed over heat-sink assemblies  128 ,  130 ,  132  to remove the heat gain. 
         [0030]    Each heat-sink assembly  128 ,  130 ,  132  is electrically hot and requires electrical insulation therebetween. Accordingly, sheets of electrical insulation  136  are disposed between each heat-sink assembly  128 ,  130 ,  132  and between framing members  122 ,  124 . Insulation  136 , by way of non-limiting example, can be ¼-inch thick glastic. 
         [0031]    To support heat-sink assemblies  128 ,  130 ,  132 , a plurality of shelves  166  extends between insulation sheets  136 . Shelves  166  are attached to insulation sheets  136  and extend therebetween. Each shelf  166  can support one of heat-sink assemblies  128 ,  130 ,  132  between adjacent insulation sheets  136 . Shelves  166  can be attached to insulation sheets  136  in a variety of ways. By way of non-limiting example, shelves  166  can be riveted to insulation sheets  136 . Shelves  166  and insulation  136  can thereby vertically support heat-sink assemblies  128 ,  130 ,  132 . Shelves  166  can form a frame with a central opening below fins  154  such that airflow across fins  154  is not prevented by shelves  166 . Shelves  166  can also be provided above heat-sink assemblies  128 ,  130 ,  132  and help maintain the proper orientation of insulation sheets  136 . The upper shelves also can form a frame with a central opening therein to allow airflow across heat-sink assemblies  128 ,  130 ,  132 . 
         [0032]    Heat-sink assemblies  128 ,  130 ,  132  and insulation sheets  136  are disposed between framing members  122 ,  124 . A jig or assembly fixture (not shown) can be utilized to initially position heat-sink assemblies  128 , 130 , 132  and insulation sheets  136  between framing members  122 ,  124 . Framing members  122 ,  124  include a plurality of pressure-applying devices  142 ,  144  that apply slight pressure P inwardly from each framing member  122 ,  124  and hold heat-sink assemblies  128 ,  130 ,  132  and insulation sheets  136  in place. Pressure-applying devices  142 ,  144  apply enough pressure P to allow the assembly jig or fixture to be removed and maintain heat-sink assemblies  128 ,  130 ,  132  and insulation  136  secure between framing members  122 ,  124 . Additionally, pressure-applying devices  142 ,  144  supply enough holding force to hold heat-sink assemblies  128 ,  130 ,  132  and insulation  136  in place during a fault condition, as described below. 
         [0033]    Pressure-applying devices  142 ,  144  can take a variety of forms. By way of non-limiting example, set screws in framing members  122 ,  124  can be used to apply pressure from framing member  122 ,  124  through insulation  136  and heat-sink assemblies  128 ,  130 ,  132  disposed therebetween and onto framing member  124 ,  122 . In an alternate configuration, a threaded rod (not shown) can be utilized as a pressure-applying device  142 ,  144 . Regardless of the form of pressure-applying devices  142 ,  144 , the use of such devices allows for easy removal and replacement of one or more of the group of heat-sink assemblies  128 ,  130 ,  132  in the event service in required. 
         [0034]    Support system  120  can also include front and rear plates  170  that extend vertically along heat-sink assemblies  128 ,  130 ,  132  between insulation sheets  136 , as shown in  FIGS. 5 and 6 . Plates  170  facilitate the airflow through heat-sink assemblies  128 ,  130 ,  132  by containing the airflow within heat-sink assemblies  128 ,  130 ,  132  as it flows therethrough. Plates  170  can be secured to insulation sheets  136  with the use of a fastener, slidable interlock, or notch in insulation sheet  136 , by way of non-limiting example. Plates  170  and shelves  166  can be sheet metal, by way of non-limiting example. 
         [0035]    Static switch  126  may include a plurality of fans  174  that are located below heat-sink assemblies  128 ,  130 ,  132 . Fans  174  can produce an airflow  176  that can flow across heat-sink assemblies  128 ,  130 ,  132  to remove heat therefrom and from static switch  126 . 
         [0036]    Each heat-sink assembly  128 ,  130 ,  132  can be associated with one phase of the power running through static switch  126 . For example, heat-sink assembly  128  can be associated with Phase A; heat-sink assembly  30  can be associated with Phase B; while heat-sink assembly  132  can be associated with Phase C. The support system  120 , according to the present teachings, can cancel some of the fault forces and thereby reduce the magnitude of the fault forces translated or transferred to the structural members, such as framing members  122 ,  124 . This is accomplished by arranging heat-sink assemblies  128 ,  130 ,  132  such that the resulting forces F during a fault condition can cancel one another, thereby reducing the net force transferred to framing members  122 ,  124  and other components of static switch  126 . In the event of a fault condition, the three electrical phases can have their individual forces act in opposite directions such that a reduction in the overall force to be absorbed by framing members  122 ,  124  is reduced. For example, as shown in  FIG. 7 , two heat-sink assemblies, such as heat-sink assemblies  128 ,  130 , will have a fault force (F 1 ) directed in the same direction (to the right in the image depicted in  FIG. 7 ), while another one of these heat-sink assemblies, such as heat-sink assembly  132 , will have twice as large a fault force (2×F 1 ) in the opposite direction (to the left in the image depicted in  FIG. 7 ). As a result, the sum of the forces theoretically can be zero. However, in actuality, the forces may not sum to zero and, as a result, some of the forces will be transmitted to framing members  122 ,  124  through pressure-applying devices  142 ,  144 . 
         [0037]    As a result, cancellation of the some of the forces associated with a fault condition can be realized and the force required to be sustained by support system  120  reduced. Additionally, with this arrangement, fault forces transferred to electrical insulators and/or conductors can be reduced and/or eliminated. Thus, the arrangement allows for the cancellation of forces associated with a fault condition such that the overall force experienced by support system  120  is reduced. 
         [0038]    Support system  120  facilitates the servicing of heat-sink assemblies  128 ,  130 ,  132 . For example, the front panel (not shown) of static switch  126  can be removed and heat-sink assemblies  128 ,  130 ,  132  and insulation sheets  136  can all be removed as a single assembly by reducing the pressure applied by pressure-applying devices  142 ,  144  and sliding them out. A jig or fixture (not shown) may be used. It may be possible to remove a single heat-sink assembly  128 ,  130 , or  132  when pressure-applying devices  142 ,  144  are loosened such that a reduction in the weight of the component to be removed is further realized. Furthermore, the ability to remove a single one of heat-sink assemblies  128 ,  130 ,  132  can facilitate the repair by only requiring removal of individual heat-sink assemblies instead of all of the assemblies together. 
         [0039]    Thus, a structural support system according to the present teachings can absorb some of the fault forces and reduce the magnitude of the fault forces translated to the structural members. The support systems can also reduce, possibly to a negligible value, the force transferred to the electrical insulators or conductors utilized in the static switch. The support system can allow the ability to remove components of the static switch, such as the heat-sink assemblies, through the front of the cabinet. This capability allows the static switches to be serviced through front access to the cabinet. The support system may eliminate the need to have access to the rear or sides of the cabinet to service the switch. Additionally, the support system can be smaller and less intrusive in nature due to the ability of the fault forces to cancel one another and/or reduce one another such that less force is transmitted to the support system. 
         [0040]    While the present teachings have been described with reference to a three-phase static switch, it should be appreciated that similar support systems can be utilized with other electrical components, such as inverters and rectifiers. However, it should be appreciated that the inverters and rectifiers may not have the large magnitude fault conditions associated with a static switch. 
         [0041]    While the present teachings have been described with reference to specific support systems, it should be appreciated that changes and deviations to the support systems can be made and such changes should not be regarded as a departure from the invention. For example, various components of the heat-sink assembles can be arranged in different orders and construction while still achieving the cancellation of forces and the reduction in the forces required to hold the heat-sink assemblies in place. Additionally, the configuration and/or orientation of the framing members can vary from that shown in order to provide a desired support for the heat-sink assemblies. Moreover, while specific pressure-applying devices are described, other pressure-applying devices may be utilized. Thus, the foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.