Patent Publication Number: US-2016248237-A1

Title: Air inlet and air outlet openings for a vertical busbar system, especially for wind power plants

Description:
PRIORITY STATEMENT 
     This patent application is a continuation of and claims priority under 35 U.S.C. §§120/121 to U.S. patent application Ser. No. 14/391,801 filed Aug. Oct. 10, 2014, which is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/EP2013/053098 which has an International filing date of Feb. 15, 2013, which designated the United States of America, and which claims priority to German patent application number DE 102012206076.6 filed Apr. 13, 2012, the entire contents of each of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Electrical distribution systems can be designed as busbar systems. Busbar systems are used to transport and distribute electrical energy. A busbar system is typically responsible for the connection from a transformer via a main distribution frame to the subsidiary distribution frame, or for the supply to bulk consumers, for example. Busbar systems are likewise used in wind power plants to conduct the current produced by a generator in the head of the tower to the foot of the tower. The busbars of a busbar system are typically housed in a busway section which prevents the occurrence of any undesired electrical contact between busbars and the environment. In this case, the busway section is so dimensioned as to provide the clearances which prevent any undesired electrical contact, and to cool the busbars within the busway section by natural or forced convection. 
     The housings of conventional busbar systems form a functional unit together with the busbars, thereby placing restrictions on the dimensioning of the busbar elements and on the ventilation of the system. When transporting energy over long vertical distances in particular, e.g. in high-rise buildings or in wind power plants, the limited ventilation and/or convection within the busway sections result in an accumulation of heat in the upper region of the installed busbar systems. 
     10 2012 202 435 DE proposes a busbar system which can comprise a plurality of busbars of different types. For example, the busbar system disclosed in  10  2012 202 435 DE may be composed of two busbar types having different cross-sectional areas and a different number of busbars of the individual types. 
     In the case of conventional busbar systems ventilated by air, the clamping point in a vertical setup position forms a barrier and thus creates a narrowed cross section A clamp  which obstructs the draft that has been warmed in free convection and flows vertically upwards. Owing to the reduced suction effect, only a very modest airflow speed v L  is achieved and therefore only a relatively small mass flow {dot over (m)} L  flows through the channel. Owing to the modest mass flow, only a small amount of heat Q can be absorbed by the airflow and carried away. There is a danger that the channel will overheat or that the heat will transfer to the periphery (e.g. housing or cover) and cause the permitted limit values for the heat to be exceeded there. 
     
       
      
       {dot over (V)} 
       L 
       =A 
       clamp 
       ·v 
       L  
      
     
         {dot over (m)}   L   ={dot over (V)}   L ·ρ L   =A   clamp   ·v   L ·ρ L  
 
         {dot over (Q)}=c   L   ·{dot over (m)}   L ·(Θ air,max −Θ air,environment )
 
     SUMMARY 
     An embodiment of the invention provides a busbar system in which there is no accumulation of heat. 
     The busbar system of an embodiment for transporting electrical energy is in a vertical setup position, said busbar system comprising at least one busbar and a cover which surrounds the at least one busbar, wherein the busbar system is divided into elements, each element having an inlet opening in a lower region of the cover and an outlet opening in an upper region of the cover, and wherein the cover is substantially closed between the inlet opening and the outlet opening of each element. 
     In one embodiment, the busbar system is divided into at least two elements. 
     In a further embodiment, the busbar system has at least two elements of different length. 
     In one embodiment, the area of the inlet opening is larger than the area of the outlet opening of each element. In particular, the area of the inlet opening can be so designed as to be 10% larger than the area of the outlet opening of each element. 
     In a further embodiment, the at least one busbar is composed of segments which are interconnected via a coupling point. 
     In one embodiment, the coupling points of the busbar segments are situated outside of the elements. 
     In a further embodiment, the coupling points are surrounded by a cover which is substantially closed. 
     In one embodiment, the busbar system for transporting electrical energy comprises at least one first segment and one second segment, the segments each comprising at least one first busbar having a first cross-sectional area, at least one second busbar having a second cross-sectional area, a retaining unit and at least one connection, wherein the busbars of the segments are retained by the respective retaining units and electrically interconnected via the at least one connection. 
     It is advantageous here that the size of the busbars can be adapted as required, since their dimensioning is not limited by a system housing. Likewise, a better thermal lift can be generated in the housing as a result of increasing the clearances of busbars from a potential housing. By virtue of this effect, the heat dissipation improves and the current carrying capacity of the busbars is increased. 
     In one embodiment, the busbars of the segments are so designed as to extend in the direction of the current flow. 
     In a further embodiment, the segments comprise a plurality of first busbars and/or a plurality of second busbars, said busbars being so arranged as to be parallel with each other in the respective segment. 
     In one embodiment, the retaining units comprise a first bolt-type connection, wherein the first busbars of the respective segments are electrically interconnected in that the ends of the first busbars lie flat against each other and the first bolt-type connection exerts a force which presses the ends of the first busbars together, said ends lying flat against each other. 
     In a further embodiment, the retaining units comprise a second bolt-type connection, wherein the second busbars of the respective segments are electrically interconnected in that the ends of the second busbars lie flat against each other and the second bolt-type connection exerts a force which presses the ends of the second busbars together, said ends lying flat against each other. 
     The retaining units of the segments can be used as retaining device(s) for fastening the busbar system. 
     In one embodiment, the first cross-sectional area of the first busbars differs from the second cross-sectional area of the second busbars. The first cross-sectional area of the first busbars may differ from the second cross-sectional area of the second busbars because the height of the first busbars differs from that of the second busbars. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described below with reference to the following embodiments and figures, in which: 
         FIG. 1A  shows a busbar system comprising a first segment and a second segment illustrated in a first projection, 
         FIG. 1B  shows a segment of a busbar system with first busbars and second busbars illustrated in a second projection, 
         FIG. 2A  shows a busbar system comprising a first segment and a second segment with a cover, 
         FIG. 2B  shows a detailed view of a retaining unit with a first and a second bolt-type connection, 
         FIG. 3  shows a busbar system comprising a first and a second segment illustrated in a third projection, 
         FIG. 4  shows an adapter for a busbar system, 
         FIG. 5  shows a top view of the tower of a wind power plant with busbar system, and 
         FIG. 6  shows a busbar system with elements. 
     
    
    
     DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
       FIG. 1A  shows a busbar system for transporting electrical energy, illustrated in a first projection of the top view of the busbar system. The busbar system comprises a first segment  701  and a second segment  702 . The segments  701 ,  702  each comprise first busbars  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  having a first cross-sectional area and a retaining unit  500 ,  501 , the busbars of the respective segments  701 ,  702  being retained by the respective retaining units  500 ,  501  and electrically interconnected via a connection  510 ,  520 . According to  FIG. 1A , the retaining unit  500  is assigned to the first segment  701  and retaining unit  501  to the second segment  702 . The connection  510 ,  520  connects the respective first busbars  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  of the first and second segments. 
     The busbars of the busbar system according to an embodiment of the invention are so designed as to extend in the direction of the current flow. According to the illustration in  FIG. 1A , this means that the current flow runs vertically and therefore the busbars are likewise so configured as to extend vertically. The individual first busbars  101 ,  102 ,  103 ,  104  of the respective segments  701 ,  702  are so arranged as to be parallel with each other. 
       FIG. 1B  shows the busbar system according to an embodiment of the invention, illustrated in a second projection. In comparison with  FIG. 1A , the illustration in  FIG. 1B  is perpendicular relative to the current flow. The retaining unit  500  retains the first busbars  100  and also has a fastening device  590  which is used as a retaining device for fastening the busbar system. The fastening device  590  may take the form of a screw, for example, such that the segments can be fastened to a wall or a support by way of the screws  590 . 
     As shown in  FIG. 1A , the segment  710  also has retainers  610 ,  620  which are attached directly to the busbars. A cover  650  may be fastened to the retainers  610 ,  620  as illustrated in  FIG. 2A . The retainers  610 ,  620  may have arms  621 ,  622 , which extend perpendicularly relative to the alignment of the busbars and which support the cover  650 . In this case, the arms  621 ,  622  of the retainers  610 ,  620  can reach through openings in the cover  650  and fix the latter thereby. In order to prevent the cover  650  from coming loose, it may be fixed by way of screws, rivets or other fastening device after the cover  650  has been placed on the busbar system. 
     The retaining unit  500  is illustrated in greater detail in  FIG. 2B . The retaining unit  500  connects the first segment  701  to the second segment  702 . The first segment  701  comprises first busbars  101 ,  102 ,  103 ,  104 . The second segment  702  comprises first busbars  101 ′,  102 ′,  103 ′,  104 ′. The first busbars of the segments  701 ,  702  are electrically interconnected in that the ends of the first busbars lie flat against each other and a first bolt-type connection  510  exerts a force which presses the ends of the first busbars together, said ends lying flat against each other. The ends of the first busbars of the respective segments  701 ,  702  may be designed in the form of a hook on one side and feature a hole on the other side, through which the bolt-type connection of the retaining unit  500 ,  501  passes. This choice of structure for the ends of the first busbars allows the segments  701 ,  702  to be assembled with particular ease. After assembly of the retaining units  500 ,  501 , the hooks can be swiveled into the bolt-type connection and the bolt-type connection tightened. 
     The first segment  701  also comprises second busbars  201 ,  202 ,  203 ,  204 ,  205 ,  206 ,  207  having a second cross-sectional area, which may differ from the first cross-sectional area of the first busbars  101 ,  102 ,  103 ,  104 .  FIG. 1B  illustrates the different cross-sectional areas of the first busbars  100  and second busbars  200 . The second busbars likewise run parallel with each other in the respective segments  701 ,  702 . According to the  FIGS. 1A, 2A and 2B , the first busbars  101 ,  102 ,  103 ,  104  and the second busbars  201 ,  202 ,  203 ,  204 ,  205 ,  206 ,  207  run parallel with each other. 
     The first cross-sectional area of the first busbars  101 ,  102 ,  103 ,  104  differs from the second cross-sectional area of the second busbars  201 ,  202 ,  203 ,  204 ,  205 ,  206 ,  207  because the height of the first busbars  101 ,  102 ,  103 ,  104  differs from that of the second busbars  201 ,  202 ,  203 ,  204 ,  205 ,  206 ,  207 . 
     According to  FIG. 2B , the retaining unit  500  comprises a second bolt-type connection  520 . The second busbars  201 ,  202 ,  203 ,  204 ,  205 ,  206 ,  207  of the first segment  701  are electrically connected to the second busbars  201 ′,  202 ′,  203 ′,  204 ′,  205 ′,  206 ′,  207 ′ of the second segment  702  by way of said second bolt-type connection  520 , in that the ends of the second busbars lie flat against each other and a second bolt-type connection  520  exerts a force which presses the ends of the second busbars together, said ends lying flat against each other. 
     According to the example embodiment illustrated here, the retaining units  500 ,  501  include the connections  510 ,  520 . However, it is equally conceivable for the connections  510 ,  520  which electrically interconnect the respective busbars of the segments  701 ,  702  to be separate from the retaining units  500 ,  501 . Consequently, the retaining units  500 ,  501  could be physically arranged at the centers of the busbars while the connections  510 ,  520  are situated at the ends of the busbars. 
       FIG. 3  illustrates the busbar system according to an embodiment of the invention in a third projection. The illustration is a lateral view of the busbar system according to  FIG. 1A  rotated by an angle of 90°. The busbar system comprises the first segment  701  and the second segment  702 . The busbars of the segments are electrically interconnected via the connection  510 ,  520  of the retaining unit  500 . The retaining unit  500  comprises a retaining device  590  for fastening the busbar system. For example, the busbar system can be screwed to a wall  800  via the retaining device  590 . The busbar system comprises retainers  610 ,  620  with arms  611 ,  621  onto which a cover  650  can be pushed and then fixed. 
     The cover  650  may be so designed as to attach only to those sides of the segments  701 ,  702  which face away from the fastening of the busbar system. According to  FIG. 3 , this means that the cover is not situated on the underside, which faces the wall  800 , but runs only along the sides of the busbars and above the busbars parallel with the wall  800 . According to  FIG. 1B , this means that the cover  650  includes three segments, specifically the segments  653  and  651  running approximately parallel with the busbars  100 ,  200  and the segment  652  running approximately parallel with a wall  800 . 
     The first busbars  100  and second busbars  200  of the respective segments  701 ,  702  can likewise be interconnected via a single bolt-type connection. 
       FIG. 4  illustrates an adapter  900 , which connects the busbar system according to an embodiment of the invention to conventional busbar systems. The busbar system according to an embodiment of the invention comprises first busbars  100  and second busbars  200 , both of which are electrically connected to the adapter  900 . Bolt-type connections can again be used as a connection. The adapter  900  likewise also has connection interfaces for a first external busbar system  910 . The first external busbar system  910  has the same number of busbars as the number of first busbars of the busbar system according to an embodiment of the invention, said busbars having the same cross-sectional areas. The adapter  900  likewise connects the second busbars of the busbar system according to an embodiment of the invention to a second external busbar system  920 . The second external busbar system  920  is a busbar system which has the same number of busbars as the number of second busbars of the busbar system according to an embodiment of the invention. The cross-sectional areas of the second busbars of the busbar system according to an embodiment of the invention are likewise identical to those of the busbars of the second external busbar system. 
     The adapter  900  can be so designed as to allow a right-angled connection interface between the busbar system according to an embodiment of the invention and the first and second external busbar systems. 
       FIG. 5  illustrates a top view of the tower of a wind power plant comprising a busbar system. A busbar system with a cover  650  is attached to the tower wall  800 . 
       FIG. 6  illustrates the tower  800  of a wind power plant in a vertical setup position. The busbar system is installed inside the tower  800 . The busbar system includes three elements  1300 ,  1301  and  1302 . Each element  1300 ,  1301 ,  1302  is provided with an inlet opening  1100  in the lower region of the cover  650  of the element  1300 ,  1301 ,  1302 , and an outlet opening  1200  in the upper region of the cover  650  of the element  1300 ,  1301 ,  1302 . The cover  650  is substantially closed between the inlet opening  1100  and the outlet opening  1200 . 
     The elements  1300 ,  1301 ,  1302  may differ in length. The elements  1300 ,  1301 ,  1302  may be formed by the segments  701 ,  702  of the busbar system. The coupling points, e.g. the first bolt-type connection  510  or the second bolt-type connection  520 , are then situated outside of the respective element. It is also conceivable for a plurality of segments of the busbar system to be situated within an element. 
     The busbar channel is so configured in its dimensions as to prevent an accumulation of heat in the region of the coupling. The busbar channel is divided by the elements into flow sections, each of which is provided with an inlet opening  1100  at the beginning (bottom) and an outlet opening  1200  at the end (top). The area of the inlet opening  1100  may be designed to be 10% larger than the area of the outlet opening  1200 , thereby boosting the chimney effect. Due to the absorption of the busbar heat and the resulting change in volume of the air, a vertical upward flow is generated which can absorb and hence carry away more heat energy in the consequently increased mass flow, without thereby exceeding the permitted housing temperature. 
     The cross section of the cover  650  should be so designed as to be significantly larger than the cross section of the busbars. 
     The inlet opening  1100  and the outlet opening  1200  may be configured such that the respective protection type of the overall system is preserved. With regard to flow, the inlet opening  1100  and the outlet opening  1200  are so configured as to ensure an optimal inflow and outflow of the air. 
     The inlet opening  1100  is configured such that air from below (cold air) can be sucked in. The outlet opening  1200  is configured such that air can flow upwards (hot air) and out in an unobstructed manner and dissipate into the environment. 
     The cover  650  and the busbars are no longer considered as unitary but as separate elements in the busbar system according to the invention, thereby providing inter alia advantages as follows. The size of the busbars can be adapted as required, since their dimensioning is not limited by a system housing. Likewise, the number of busbars and the cross-sectional area of the busbars are variable and can be selected to suit the individual application. For example, a housing may contain a busbar system comprising four first busbars and seven second busbars. By increasing the clearances of busbars from the cover, it is possible to generate a better thermal lift in the cover (chimney effect). By virtue of this effect, the heat dissipation improves and the current carrying capacity of the busbars is increased. An additional cost benefit is achieved by combining a plurality of busbars having different cross-sectional areas under one cover.