Abstract:
The disclosure relates to a transformer having a yoke which has a crosspiece and at least two limbs, over which limbs a coil is placed in each case, and having at least one carrier on which the crosspiece is fixed and which has bearing faces for the coils. At least two supporting blocks for each coil are mounted on each bearing surface. The supporting blocks are fitted with elastic compensation elements on the coil-side carrying face and have, on their longitudinal side faces, which run perpendicular to a carrying surface, at least one strip which extends the creepage path and runs in the longitudinal direction and parallel to the carrying surface of the supporting block.

Description:
RELATED APPLICATIONS 
     This application claims priority as a continuation application under 35 U.S.C. §120 to PCT/EP2009/001095, which was filed as an International Application on Feb. 17, 2009 designating the U.S., and which claims priority to German Application 10 2008 010 548.1 filed in Germany on Feb. 22, 2008. The entire contents of these applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD 
     The disclosure relates to a transformer for example, a two- or multiphase transformer and to supporting blocks for a transformer. 
     BACKGROUND INFORMATION 
     The disclosure relates, for example, to dry transformers or cast-resin/resiblock transformers with appropriate coil supports. These coil supports can be composed of plastic, and can be arranged below and/or above the coil. A function is to support the weight of the coil. Measures can be taken to lengthen the creepage distance. This can be achieved by plates which are adhesively bonded in between individual parts of the coil supports. For example, when a long creepage distance is desired, it may be desirable to adhesively bond a single coil support or a coil supporting block composed of a large number of individual parts, in order to achieve the lengthening of the creepage distance. 
     The production of such transformers can be costly. 
     SUMMARY 
     A transformer is disclosed comprising: a yoke which has a web and at least two limbs; a coil placed over each of the limbs; at least one mount, to which the web is fixed and which has plural bearing surfaces for plural transformer coils; at least two supporting blocks for each coil placed on each bearing surface; elastic compensation elements fitted to a coil-side mounting surface of the supporting blocks; and at least one strip on longitudinal side surfaces of the supporting blocks which run at right angles to the mounting surface, to lengthen a creepage distance, wherein the at least one strip runs in the longitudinal direction and parallel to the mounting surface of the supporting blocks. 
     A supporting block is disclosed for supporting a transformer having coils, the supporting block comprising: a coil side mounting surface for receiving a multiphase transformer coil; an elastic compensation element fitted to the coil-side mounting surface for receiving a multiphase transformer coil; and at least one strip formed on longitudinal side surfaces which run at right angles to the mounting surface and configured to lengthen a creeping distance of the supporting block, wherein the at least one strip runs in a longitudinal direction and parallel to the mounting surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure as well as further advantageous refinements and improvements, and further advantages, will be explained and described in more detail with reference to the drawings, which illustrate a number of exemplary embodiments of the disclosure, and in which: 
         FIG. 1  shows a section view of an exemplary embodiment of supporting blocks along the section line I-I in  FIG. 2 , 
         FIG. 2  shows a section view of an exemplary embodiment of supporting blocks corresponding to the section line II-II in  FIG. 1 , 
         FIG. 3  shows a section view similar to that in  FIG. 1 , with an exemplary embodiment of two supporting blocks, 
         FIG. 4  shows an exemplary embodiment of a supporting block, illustrated in perspective form, and 
         FIG. 5  shows a view of an exemplary embodiment of a supporting block for height matching, similar to  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure relates to a transformer in which the coil can be supported by as few supporting blocks as possible, with the production of a sufficiently long creepage distance being simplified. 
     According to an exemplary embodiment of the disclosure, at least two supporting blocks for each coil can be placed on each bearing surface, which have elastic compensation elements fitted to the coil-side mounting surface, and which, on their longitudinal side surfaces, which run at right angles to the mounting surface, have at least one strip which lengthens the creepage distance. The strips run in the longitudinal direction and parallel to the mounting surface of the supporting block. 
     An exemplary embodiment of a supporting block is disclosed which, for example, can be produced using a so-called pultrusion process and in which, as a result of the selection of the shape, a lengthened creepage distance can be provided from the start on the longitudinal side surfaces of the supporting blocks. 
     According to an exemplary embodiment of the disclosure, at least one supporting block can have at least one slot on its end surfaces. The slots can be introduced in the direction of the mounting surface and parallel to it and can likewise be used to increase the creepage distance. 
     The at least one slot can, for example, be introduced outside the area of the strips. 
     According to an exemplary embodiment of the disclosure, at least one of the supporting blocks can be hollow. This reduces the amount of insulating material. The supporting block can therefore be lighter, and the internal cavity can also prevent stress cracks during curing. 
     The at least one hollow supporting block can have at least two, and in exemplary embodiments three, strips, depending on the desired length of the creepage distance. 
     In order to produce a supporting block, the strand produced using the pultrusion process can be shortened, with the supporting block being cut to the desired length easily from a long profile. 
     When a plurality of supporting blocks, for example two supporting blocks, are stacked one on top of the other, one supporting block can have a strip-like projection on the contact plane and the other can have a depression matched to it. The projection and depression run in the longitudinal direction, wherein the projection fits into the depression such that the two supporting blocks can be guided with respect to one another by the projection and the depression, in a similar manner to a tongue and groove. 
     The supporting blocks can have different heights. For example, it is possible to use a profile with a shorter height, thus allowing the height of the assembled supporting blocks to be matched to the specifications. Furthermore, a strip can also be integrated between the coil and the supporting block, in order to compensate for unevennesses of the coils. The strip may be composed of an elastic material, for example, a silicone rubber. 
     Reference will now be made to  FIG. 1 . 
     Two double-T mounts  10  and  11  can be provided on a base NN and are mounted thereon. A coil  17  is placed on the opposite surfaces  14  of the upper lateral webs  12 ,  13  of the double-T mounts  10 ,  11  to the base, with the interposition of supporting blocks  15  and  16 . 
     The supporting block  15  is illustrated in more detail in  FIG. 4 . 
     In a cross section at right angles to its longitudinal extent, the supporting block  15  has an approximately rectangular shape with a specific height H and a width B. The width B is less than the height H. The supporting block  15  has an internal cavity  18 , thus reducing the weight and the amount of material used. An upper contact surface  19  and a lower contact surface  20 , each having a width B, are provided on the supporting block  15 . The length of the supporting block  15  depends on the size of the coil  17 . There are grooves  21  and  22  in the contact surfaces  19  and  20 , with a centering profile  23  being inserted into the groove  21  in the illustration shown in  FIG. 4 , and being used to provide twisting protection between two supporting blocks  24   1  and  24   2  which are arranged one on top of the other. See  FIG. 3 . The supporting blocks  24   1  and  24   2  in  FIG. 3  differ from the supporting block  15  shown in  FIG. 4  by not having a cavity  18 . 
     Strips  27  and  28  can be provided on the side surfaces  25  and  26 , which are at right angles to the contact or mounting surfaces  19  and  20 . The strips  27  and  28  project outwards, run in the longitudinal direction of the supporting block  15  and project in the opposite direction outwards from the side surfaces  25  and  26 , thus lengthening the creepage distance between the coil  17  and the double-T mounts  10 ,  11  on both side surfaces. The corresponding strips of the supporting blocks  24   1  and  24   2  are not provided with reference numbers there. 
     As can be seen from  FIG. 2 , slots  31  and  32  can be provided on the end surfaces  30  of at least the supporting block  15 , can be located outside the area of the strips and lengthen the creepage distance in the area of the end surface  30 . 
     In addition to the supporting block  15 ,  FIG. 1  shows two supporting blocks  16   1  and  16   2 , which are illustrated in  FIG. 5 . These have a width B which corresponds to the width of the supporting blocks  15  and a height h which is less, and in certain circumstances considerably less, than the height H of the supporting blocks. These supporting blocks  16   1  and  16   2  can be used to match the supporting blocks to the distance between the coil and the contact surface  14  of the mounts  10 ,  11 . The supporting blocks  16   1 ,  16   2 , which may be referred to as compensation pieces, have a projection  33  on the upper face (in the drawing) and, on the lower face, have a depression  34  which runs in the longitudinal direction, parallel to the projection  33 , and corresponds to the depression  22 . The projection  33  is of such a size that it can engage in the corresponding depression  22  in a further supporting block which is placed over the compensation piece  16 , as is illustrated in  FIG. 1 . 
     A strip  35  composed of elastic material can be inserted into the groove or depression  21  (see  FIG. 4 ) between the supporting block  15  and the coil  17 , for example a strip composed of silicone rubber material, which can be used to compensate for any unevennesses on the lower face of the coil  17 . The strips  35  may have the same dimensions as the centering profile  23 . 
     Corresponding flat compensation materials can, of course, also be inserted between the individual supporting blocks  15  and compensation pieces  16   1 ,  16   2 . In this case, the centering profiles  23  can be adhesively bonded into the depression  21 . As can be seen from  FIG. 3 , two plates  37  can be inserted between the lower supporting block  24   2  and the contact surface  14  of the mount  10  or  11 , and are used as compensation plates. More than two compensation plates or just one can, of course, also be provided. 
     It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein. 
     List Of Reference Symbols 
     
         
           10  Double-T mount 
           11  Double-T mount 
           12  Lateral web 
           13  Lateral web 
           14  Surface 
           15  Supporting block 
           16  Supporting block 
           16   1  Supporting block 
           16   2  Supporting block 
           17  Coil 
           18  Cavity 
           19  Upper contact surface 
           20  Lower contact surface 
           21  Groove 
           22  Groove 
           23  Centering profile 
           24   1  Supporting block 
           24   2  Supporting block 
           25  Side surface 
           26  Side surface 
           27  Strip 
           28  Strip 
           30  End surface 
           31  Slot 
           32  Slot 
           33  Projection 
           34  Depression 
           35  Strips