Abstract:
The invention relates to a method for repairing a power rail housing ( 100 ) of a wind power plant ( 10 ), in which the power rail housing ( 100 ) is composed of a plurality of power rail housing sections ( 32, 33 ) each having an at least essentially rectangular cross section and being connected to one another in the longitudinal direction, wherein the connection of the power rail housing sections ( 32, 33 ) is carried out by means of preferably plate-shaped connecting elements ( 37, 38 ), said power rail housing sections ( 32, 33 ) covering a connecting region of power rails ( 27  to  29 ) within the power rail housing ( 100 ), wherein the connecting elements ( 37, 38 ) are connected by means of screws ( 42, 43 ) to the two power rail housing sections ( 32, 33 ) which adjoin one another in the longitudinal direction.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a method for repairing a power rail housing of a wind power plant. Furthermore, the invention relates to a power rail housing repaired according to the method according to the invention, and to a repair kit for carrying out the method. 
     Within a tower of a wind power plant the power rails, which are provided for carrying the current and which comprise, in particular, aluminium, are arranged within a multi-component power rail housing. By means of the power rail housing, in particular, direct access or direct contact and thus the danger of shortcuts in the current-carrying power rails are prevented. In practical application such a power rail housing comprises a multitude of interconnected power rail housing sections that on the sides that face each other are interconnected by means of connecting elements. These connecting elements are, in particular, designed in the form of cover plates or perforated plates that at the same time cover the connecting region between the power rails. The connecting elements are arranged at opposite sides of the power rail housing having an at least essentially rectangular cross section. A rear connecting element or cover plate is situated on the side facing the inner wall of the tower, while a front cover plate faces the interior of the tower. After removal, for example, of the front connecting element (cover plate) the connecting region between the power rails can be inspected or serviced. 
     Already during installation of the individual power rail housing sections, or in the course of maintenance work or similar, due to installation faults or inaccuracies during installation it can occur that, for example, a screw that is used to connect the cover plate to the power rail housing sections is pulled from a thread region, or that the thread provided in the power rail housing section for anchoring the screw, which thread has been put in place beforehand, is damaged. As a result of this, re-installation of the connecting element or of the cover plate is then impossible. Thus, in practical application, for the sake of simplicity or because of the lack of alternatives, the corresponding power rail housing section comprising the faulty or damaged thread or the pulled-out screw situated in the thread is disposed of and replaced with a new power rail housing section. If delays in installation, service or repair are to be avoided, the aforementioned procedure makes it necessary for wind power stations to keep corresponding power rail housing sections in stock as spare parts. Furthermore, such an exchange is relatively expensive, if nothing else for reasons associated with investment in the power rail housing section to be replaced. 
     DISCLOSURE OF THE INVENTION 
     Based on the knowledge of prior art described above, it is the object of the invention to provide an economically advantageous method for repairing a power rail housing of a wind power plant. According to the invention this object is met by a method for repairing a power rail housing of a wind power plant with the characteristics disclosed herein. According to the invention it is essentially provided that if there is a damaged or unusable thread in a power rail housing section, in a first step the region of the thread is enlarged in diameter; that in a second step, lining up with the thread, a carrier element that comprises a replacement thread for the screw is connected to the power rail housing section comprising the damaged thread; and in that in a third step, for installation of the connecting element, the screw is fed through the enlarged-diameter region of the power rail housing section and is screwed into the replacement thread. In other words, this means that with the use of the carrier element, which represents a separate and additional component, a new option for anchoring the screw is provided, wherein as a result of enlarging or drilling open the original thread region in the power rail housing section it is ensured that the screw can be fed through the original region of the power rail housing section or of the thread, and can be made to establish an operative connection with the replacement thread comprised in the carrier element. Such a repair method according to the invention makes it possible to further use the original power rail housing section, and to prevent it from having to be disposed of. Thus, in contrast to prior art it is not necessary to keep in stock at the wind power plant, for example, power rail housing sections as replacements for power rail housing sections that are no longer usable. 
     Advantageous improvements of the method according to the invention for repairing a power rail housing of a wind power plant are also stated herein. Any combinations comprising at least two characteristics disclosed in the claims, in the description and/or in the figures are within the scope of the invention. 
     Especially preferred is a method in which the carrier element is connected to the power rail housing section by means of an adhesive layer. This makes it possible that for installation of the (new) screw the carrier element is pre-positioned or fixed at the intended location within the power rail housing section, without other fastening elements for the carrier element having to be used for this, which fastening elements would otherwise render installation more difficult or impossible. 
     As an alternative or in conjunction with the above-mentioned adhesive layer, in a further particularly preferred variant of the invention it is provided that the carrier element is connected to the wall of the power rail housing section by means of an additional screw, wherein an additional through-hole is formed in the wall of the power rail housing section, and an additional thread is formed in the carrier element. Such a method makes it possible to mechanically fix and position the carrier element within the power rail housing section, and consequently said carrier element is positioned during installation of the connecting element or of the screw on the place provided for this purpose within the enlarged-diameter hole of the original thread. 
     In particular in cases where additional components for positioning the carrier element are undesirable for reasons of design and construction, or where they interfere during installation of the connecting elements, moreover, in a further embodiment of the invention it is provided that with the use of an adhesive layer the additional screw is removed prior to the third step (screwing the screw into the replacement thread in the carrier element) being carried out. Such removal of the screw is possible as soon as the adhesive layer affixes or holds the carrier element in the power rail housing section after a corresponding curing time. Depending on the type of adhesive used, in practical application even a few minutes are sufficient, and consequently the actual repair process is not prolonged as a result of this. 
     A further advantageous method provides that if there are several screws in the region of a longitudinal side of the power rail housing section, the diameters of all the threads in the power rail housing section are enlarged, and that for each thread the carrier element comprises a replacement thread. As a result of this it is always sufficient to use a single standardised carrier element in which, in advance according to the (known and standardised) hole pattern, corresponding replacement threads for the threads in the power rail thread sections have been formed. As a result of this it is, in particular, not necessary to make corresponding replacement threads in the carrier element on site, i.e. in the region of the wind power plant, and consequently handling is further simplified. 
     The invention also relates to a power rail housing comprising at least one power rail housing section in which the aforesaid was repaired according to a method according to the invention and comprises a carrier element that is connected to a power rail housing section. Such a power rail housing provides an advantage in that it can also be used subsequently, if applicable in some other location in the wind power plant, because said power rail housing in its functionality corresponds to a new power rail housing section. 
     For carrying out the method according to the invention, furthermore, a repair kit is provided that comprises at least one preferably strip-shaped carrier element with at least one replacement thread and with auxiliary means for fastening the carrier element to a wall of the power rail housing section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics, advantages and details of the invention are stated in the following description of preferred exemplary embodiments and with reference to the drawing. 
       The drawing shows in: 
         FIG. 1  a greatly simplified longitudinal section of a wind power plant, 
         FIG. 2  a cross section of the connecting region between two power rail housing sections, 
         FIG. 3  a view in the direction of the arrow III of  FIG. 2 , 
         FIG. 4  an enlarged view of a detail of  FIG. 2 , 
         FIG. 5  a flow chart for illustrating the repair method according to the invention, and 
         FIG. 6  a detailed view of a carrier element as part of a repair kit. 
     
    
    
     In the figures, identical elements or elements with similar functions have the same reference characters. 
     DETAILED DESCRIPTION 
       FIG. 1  is a greatly simplified view of the basic design of a wind power plant  10 . The wind power plant  10  comprises a tower  11  that is arranged on a base  12 . At the top of the tower  11  a nacelle  13  is arranged in which, among other things, the rotor blades  14  are rotationally held. Within the nacelle  13  there is a generator  16 . The generator  16  is coupled to an upper connecting line  17  and to an upper connection with an arrangement  18  of interconnecting power rails (merely hinted at). The arrangement  18  of interconnecting power rails extends over the entire length or height of the tower  11 . In the region of the base  12  of the tower  11  the arrangement  18  of interconnecting power rails is connected to a power grid station  22  by means of a further, lower connecting line  21  or a lower connection. 
     The tower  11  comprises, for example, three sleeve-like tower segments  24  to  26 , arranged one over the other. Such a tower segment  24  to  26  typically comprises a length of approximately 20 m, so that the overall height of the tower  11  (without the nacelle  13 ) is approximately 60 m. Within each tower segment  24  to a multitude of power rails  27  to  29  extend as part of the arrangement  18  of interconnecting power rails, in particular in the form of elongated aluminium rails. Each of the power rails  27  to  29  forms a phase of a rotary current line, wherein for example according to  FIG. 2  in each case six power rails  27  to  29  (i.e. twice three phases) are provided. In this arrangement, within each tower segment  24  to  26  (when viewed in the longitudinal direction of the tower segment  24  to  26 ), in each case several power rails  27  to  29  can be provided. It is essential that in the connecting region shown in  FIG. 2 , between two tower segments  24 ,  25  or  25 ,  26 , the power rails  27  to  29  associated with the respective tower segment  24  to  26 , or situated within said tower segment  24  to  26 , are interconnected in the longitudinal direction so that the electrical through-arrangement  18  of interconnecting power rails is formed that is coupled to the two connecting lines  17 ,  21 . 
     The connection between the individual power rails  27  to  29  takes place, for example, by means of a terminal connector  30 , shown in  FIG. 2 , which terminal connector  30  engages apertures or slits formed in the power rails  27  to  29 , and which terminal connector  30  presses the power rails  27 ,  28  against each other in order to establish an electrical connection between the power rails  27  to  29  of the tower segments  24  to  26 . Moreover, it is in particular necessary to arrange insulating elements or insulating plates  31 , which comprise a ceramic material, between the individual power rails  27  to  29 , which insulating elements or insulating plates  31  electrically insulate the individual power rails  27  to  29 , each of which forms a phase. 
     The arrangement  18  of interconnecting power rails is housed within a power rail housing  100  that typically extends over the entire length of the arrangement  18  of interconnecting power rails or of the tower segments  24  to  26 . The power rail housing  100 , which has an at least essentially rectangular cross section, again comprises a multitude of power rail housing sections  32 ,  33  interconnected in the longitudinal direction. In the illustration according to  FIG. 1  it is assumed that the respective upper power rail housing sections  32  in the tower segments  24  to  26  are connected to the respective lower power rail housing sections  33  in the tower segments  25 ,  26 . Of course, it is possible or provided for that within each tower segment  24  to  26  the power rail housing  100  comprises a multitude of interconnected power rail housing sections  32 ,  33 , which in each case typically have a length of, for example, 2 m. 
     The power rail housing  100  is used to protect from manipulation or contact the power rails  27  to  29  arranged within the power rail housing  100  or the arrangement  18  of interconnecting power rails. In particular it must be ensured that no electrical short circuits occur between the individual power rails  27  to  29 . 
     In order to make it possible to compensate for movements of the tower  11  of the wind power plant  10  or movements of the individual tower segments  24  to  26 , the power rail housing sections  32 ,  33  between the tower segments  24 ,  25  or  25 ,  26  are arranged with a small axial gap  34  of, for example, 10 mm. On the side facing the inner tower wall  35 , and on the side facing away from the inner tower wall  35  the tower rail housing sections  32 ,  33  are interconnected by means of a respective front or rear connecting element  37 ,  38 . In particular, the connecting elements  37 ,  38  cover the connecting region between the power rails  27  to  29  of the individual tower segments  24  to  26 . 
     The connecting elements  37 ,  38  are, for example, in each case designed as cover panels or cover plates with longitudinal strips  39 ,  40  comprising a perpendicular return edge. The connecting elements  37 ,  38 , which in the longitudinal direction are arranged in the middle of the axial gap  34 , are laterally, on the power rail housing sections  32 ,  33 , connected by means of through-holes, formed on the longitudinal strips  39 ,  40 , in each case with the use of two screws  42 ,  43 , to the corresponding power rail housing section  32 ,  33 , wherein the arrangement of the screws  42 ,  43  takes place in the longitudinal direction of the power rail housing  100 . Thus for each of the connecting elements  37 ,  38  eight screws  42 ,  43  are used. 
     In order to form the screw connections, in a section of the power rail housing  32 ,  33  which section comprises a U-shaped cross section, the power rail housing sections  32 ,  33  in each case comprise a threaded hole  44 ,  45 . The threaded hole  44 ,  45  comprises, for example, typically an M6 thread. For installation or after corresponding service or repair of the power rail housing sections  32 ,  33  it is necessary to reinstall the previously removed connecting elements  37 ,  38  on the power rail housing sections  32 ,  33 . Because of faulty installation, component tolerances or similar it can happen that during installation of a connecting element  37 ,  38  when screwing in a screw  42 ,  43  said screw  42 ,  43  is pulled out in the region of the threaded hole  44 ,  45 , or that during installation of the screw  42 ,  43  the associated threaded hole  44 ,  45  is damaged and consequently can no longer be used for installation of the screw  42 ,  43 . To make it possible to nevertheless continue to use the existing power rail housing section  32 ,  33 , according to the invention it is provided to repair the power rail housing section  32 ,  33  of the power rail housing  100 , which power rail housing section  32 ,  33  comprises the defective threaded hole  44 ,  45 . 
     In accordance with  FIG. 5  the repair according to the invention provides for at least the following steps: initially, in a first step  50 , both the diameter of the affected defective threaded hole  44 ,  45  and the diameter of the other (undamaged) threaded hole  45 ,  44  in the respective region of the power rail housing section  32 ,  33  is enlarged or drilled out. If the (original) threaded hole  44 ,  45  comprises, for example, an M6 thread, the threaded holes  44 ,  45  are, for example, enlarged or widened to a diameter of 8 mm. Subsequently, in a second step  51 , a carrier element  60  is placed in the region of the threaded hole  44 ,  45 . 
     The carrier element  60 , shown in an individual view in  FIG. 6 , preferably forms part of a repair kit  70  and comprises, for example, a non-corrosive material, in particular stainless steel, and is strip-shaped in design with a thickness of, for example, 4 mm. The strip-like design of the carrier element  60  results from the design of the power rail housing  100 , which design is U-shaped in the region of the threaded hole  44 ,  45 . Preferably, but not limiting, the carrier element  60  is of such a length that within the carrier element  60  two replacement threaded holes  61 ,  62  are formed whose hole pattern or spacing corresponds to the hole pattern or spacing of the (original) threaded holes  44 ,  45 . In this arrangement the replacement threaded holes  61 ,  62  are identical in size to the original threaded holes  44 ,  45 ; in the described exemplary embodiment they are thus M6 threaded holes  61 ,  62 . Furthermore, for example, in the region between the two replacement threaded holes  61 ,  62  there is a further threaded hole for example in the form of an M4 thread. Fastening of the carrier element  60  to the power rail housing  100  in the region of the damaged threaded hole  44 ,  45  takes place in that (preferably by means of a template) corresponding to the hole pattern of the replacement threaded holes  61 ,  62  and of the further threaded hole  63  an additional hole is formed on the carrier element  60  on the power rail housing section  32 ,  33  of the power rail housing  100 , which additional hole is associated with the further threaded hole and comprises a somewhat larger diameter than the external diameter of the screw used for the further threaded hole  63 , in order to be able to better position or centre the carrier element  60 . 
     Furthermore, it is provided that on the facing surfaces of the power rail housing  100  or of the power rail housing section  32 ,  33  to be repaired, and on the carrier element  60  (i.e. on the side of the power rail housing section  32 ,  33 , which side faces away from the connecting element  37 ,  38 ) an adhesive layer  64  is applied that also forms part of the above-mentioned repair kit  70 . The second step  51  (fastening the carrier element  60  to the tower rail housing section  32 ,  33  to be repaired) provides that first the corresponding adhesive layer  64  is applied to the carrier element  60  and subsequently, by means of a further screw  65  (which also forms part of the repair kit  70 ) the carrier element  60  is positioned in such a manner, within the power rail housing section  32 ,  33  to be repaired, that the replacement threaded holes  61 ,  62  are aligned with the original threaded holes  44 ,  45  or with the enlarged-diameter regions. In order to prevent the adhesive layer  64  resulting in movement of the carrier element  60  during the curing phase, by means of the further screw  65  the carrier element is temporarily fastened or fixed to the corresponding power rail housing section  32 ,  33 . As soon as the curing phase of the adhesive layer  64  is completed, which, for example, typically only takes approximately 10 min. to 15 min., the further screw  65  can be removed. Subsequently, in a third step  52 , installation of the connecting element  37 ,  38  takes place by fastening the screws  42 ,  43  in the replacement threaded holes  61 ,  62  of the carrier element  60 . Repair of the power rail housing  100  is thus complete. 
     In addition it should be mentioned that hitherto only the most necessary steps  50  to  52  of the repair method according to the invention have been described. Beyond this it can be provided to carry out further method-related steps, either during the method for repairing or beforehand, which further steps are used for servicing or for ensuring an impeccable repair outcome. For example it can be provided that during the repair basically the connecting screw or the terminal connector  30  between the power rails  27  to  29  is replaced. Furthermore, in particular after drilling open or enlarging the original threaded hole  44 ,  45 , the corresponding regions are vacuum-cleaned in order to remove from the power rail housing  100  any metal shavings that may be present. Moreover, it can be provided that on completion of the installation a screw-lock lacquer is applied to the screws  42 ,  43  in order to secure said screws  42 ,  43 . The method described so far can be altered or modified in a host of ways without deviating from the scope and nature of the invention. For example, it can be provided that for repair the corresponding power rail housing sections  32 ,  33  are removed from the tower  11  of the wind power plant  10  in order to make it possible to gain improved access to the power rail housing sections  32 ,  33 . Furthermore, it is imaginable, in a modification of the exemplary embodiment shown, to use a carrier element  60  that comprises only a single replacement threaded hole  61 ,  62  arranged in the location in which the damaged threaded hole  44 ,  45  is situated. In this case, however, typically there is a need to use carrier elements  60  of a different design. However, such a method or such modified carrier elements  60  provide an advantage in that there is no need to drill open or enlarge the originally undamaged threaded hole  44 ,  45 . Moreover, it is imaginable to fix the carrier element  60  during the curing time of the adhesive layer  64  not by means of the further screw  65  but instead by means of other suitable clamping elements, for example screw clamps, clamping claws or similar.