Patent Publication Number: US-2021174991-A1

Title: Insulator having an end fitting and a connecting device as well as arrangement for dissipating overvoltage

Description:
The invention relates to an insulator according to the precharacterizing clause of claim  1  and an arrangement according to claim  11 . 
     Composite long-rod insulators are known, for example, from the product brochure “Silikon-Langstabisolatoren 3FL für Mittel- and Hochspannungsfreileitungen”, [“3FL Silicone long-rod insulators for medium- and high-voltage overhead lines”] Siemens AG 2011, Order No. E50001-G630-A193. The long-rod insulators have a rod made from glass fiber reinforced plastics (GFP), to the ends of which a metal end fitting is applied in each case. A silicone sheath with shields for creepage path extension is provided as the housing. The end fittings can have a multiplicity of different forms at their end remote from the housing. These forms are provided for connecting or suspending the insulator and are described in standards IEC 61466-1, IEC 60120 and IEC 60471. Typical forms according to page 5 are ball, socket, joint fork, joint plate, Y-fork and eye. 
     An insulator is protected from corona effects and short-circuit arcs with the aid of protective rings. Such protective fittings are connected to the insulator, i.e. connected to an end fitting, via additional fittings. These connections between the insulator and additional fittings are generally supported flexibly in order to not transmit bending stresses to the insulator. For example, a line arrester with an external spark gap can be connected to the insulator via additional fittings. Such externally gapped line arresters (EGLA) are known, for example, from pages 10 and 11 of the product brochure “Leitungsableiter für erhöhte Systemzuverlässigkeit” [“Line arresters for increased system reliability”], Siemens AG 2012, Order No. E50001-G630-A203. 
     The object of the invention is to specify an insulator which can be connected to an operating means in a particularly simple and reliable manner. 
     The invention achieves this object by means of an insulator according to claim  1 . 
     The invention is based on the problem of there being applications in which the operating means should be supported on the insulator in a fixed, movement-free manner. This is the case, for example, if a spacing of the protective rings from the center of the insulator is to be constant or if other protective devices, for example a line arrester, are to be installed. In this case, within the context of the invention, fixed in a movement-free manner means mounted without degrees of freedom. In particular, in the case of a line arrester with an external spark gap, all degrees of freedom are to be eliminated in order to keep the length of the spark gap constant, even in the event of a movement of the insulator, for example due to vibrations caused by wind. 
     In the prior art, combinations of a joint fork with an additional fitting with a plate have been hitherto provided. In this case, the fitting is geometrically designed such that the plate rests extensively in the fork and is therefore fixed in place. This requires a high degree of precision during manufacture. Moreover, this design is never free of movement. The invention solves this problem by means of the single-piece design, in which the end fitting is combined with the connecting device. Two components are therefore replaced by a single component, which eliminates all degrees of freedom of this connection. The position of the attached components is fixed. A further advantage is that it saves on material and the installation effort is reduced. 
     In a preferred embodiment of the inventive method, the insulator is a long-rod insulator. This is an advantage since long-rod insulators are time-tested and widely used. 
     In a preferred embodiment of the inventive method, the connecting device has a contact portion for mounting the additional operating means. This is advantageous since simple fastening of additional parts to the end fitting is possible by means of the contact portion. 
     In a further preferred embodiment of the inventive method, the contact portion has at least one cutout for attaching the additional operating means. This is an advantage since a guiding-through of a fastening means, for example a bolt or a screw with a nut, is enabled by the cutout. This contributes to slip-free attachment. 
     In a preferred development of the above-mentioned embodiment, the contact portion has at least two boreholes for attaching the additional operating means. This is an advantage since two screws with nuts for fastening purposes can be used as a result of the boreholes. 
     In a further preferred embodiment of the inventive method, the connecting device has a suspension portion with a means for suspending the insulator. This is an advantage since insulators are often used on masts for high-voltage overhead lines. In this case, a suspended attachment is often used in order to prevent bending loads on the insulator as a result of vibrations of the mast or wind affecting the insulator. 
     In a preferred development of the above-mentioned embodiment, the suspension portion has at least one of the following forms: ball, socket, joint fork, joint plate, Y-cable, eye. Numerous different means of suspension can therefore be selected as required. 
     In a further preferred embodiment of the inventive insulator, the end fitting with the connecting device consists substantially of metal. This is preferably steel or aluminum. This is an advantage since using a metal end fitting is cost-effective in terms of production and the metal end fitting is robust and durable. 
     In a further preferred embodiment of the inventive insulator, the end fitting with the connecting device is produced in one piece in a casting process. This is an advantage since metal workpieces in virtually any desired form can be produced in a simple and cost-effective manner by means of a casting process. 
     The invention is furthermore based on the object of specifying an arrangement for dissipating overvoltage, which can be installed in a particularly simple manner and is comparatively reliable. 
     The invention achieves this object by means of an arrangement according to claim  11 . Preferred embodiments of the inventive arrangement are revealed in claims  12  to  15 . Essentially the same advantages as those explained at the outset for the inventive method are revealed for the inventive arrangement and its embodiments. 
    
    
     
       For better explanation of the invention, in a schematic illustration: 
         FIG. 1  shows a first known connecting device; and 
         FIG. 2  shows a second known connecting device; and 
         FIG. 3  shows a known arrangement with two insulators; and 
         FIG. 4  shows a further known arrangement with an insulator and two overvoltage arresters; and 
         FIG. 5  shows a detailed view of the known arrangement according to  FIG. 4 ; and 
         FIG. 6  shows an exemplary embodiment of the inventive insulator; and 
         FIG. 7  shows an exemplary embodiment of an inventive arrangement with an insulator. 
     
    
    
       FIG. 1  shows a connecting device  1  with a first eye  71 , a contact portion  2  for mounting an additional operating means and a second eye  3 . In this case, the eyes  3 ,  71  are formed as substantially flat metal rings, wherein the planes of the substantially flat metal rings are perpendicular to one another. On the other hand, in the second example for a connecting device  4  according to  FIG. 2 , the eyes  5 ,  71  are arranged in one plane. The connecting device  1  according to  FIG. 1  enables an insulator to be mounted by means of the eye  71 , for example, and enables this insulator to be mounted on a mast by means of the eye  3  such that it is rotated through 90 degrees in relation to the suspension device. This enables an orientation of the further operating means mounted on the contact portion  2 . This is not the case in  FIG. 2 : this connecting device  4  arranges the mast suspension device and the insulator in the same orientation, and therefore also the connected further operating means. 
       FIG. 2  shows an arrangement  6 , known in the prior art, with two long-rod insulators  7 ,  8 . The long-rod insulators are connected to protective fittings  11 ,  12  via connecting devices  22 ,  24 , which are mounted on the respective end fittings  17 ,  18  of the insulators  7 ,  8 . The protective fittings  11 ,  12  are corona rings and have webs  15 ,  16 . The connecting devices  22 ,  24  are moreover connected to mast attachments  13 ,  14  in each case. On the side of the insulators  7 ,  8  which is situated at the bottom corresponding to the suspension direction, the respective end fittings  21 ,  22  are in turn connected to corona rings  9 ,  10  via connecting devices  25 ,  26  and webs  19 ,  20 . A spacer  27  in a substantially Y-shaped arrangement is provided to prevent a clashing together of the suspended insulators  7 ,  8 . This spacer  27  is in turn connected via a connecting device  28  to a conductor fitting  29  for connection to an overhead line conductor (not illustrated). 
     In the known arrangement  6 , the connecting devices  22 ,  24 ,  25 ,  26  are used to provide a certain flexibility in the suspension of the insulators  7 ,  8  and to therefore prevent the transmission of bending stresses to the long-rod insulators  7 ,  8 . 
       FIG. 4  shows a known arrangement  30  with a long-rod insulator  31 . The long-rod insulator  31  is connected to two arms  32 ,  33  in each case via inventive connecting devices  36 ,  37 . The arms  32 ,  33  each support an overvoltage arrester and a spark horn  34 ,  35  so that an isolating distance of length D is provided in air between the spark horns  34  and  35 . This arrangement provides a so-called externally gapped line arrester (EGLA). 
       FIG. 5  shows a detail in the region of the inventive connecting device  37 . The arrester on the arm  33  is connected via a base plate  51 , which is mounted by means of a screw  52 . On the base plate  51 , an attachment bar  53  projects at a perpendicular angle to this base plate  51 . This attachment bar  53  has two bores for receiving screws  54 ,  55 . In this case, one bore is formed as a slot  56  so that a rotation of the base plate in a plane which is vertical (with respect to the ground) is enabled after the positioning of the screw  55  in the slot  56 . This enables the isolating distance D to be be adjusted and fixed in terms of its length. In this case, the arrow  57  denotes the direction of rotation along the opening specified by the slot  56 . The screws  54 ,  55  attach the base plate  51  and the attachment bar  53  to a holding web  47 . The holding web  47  has a portion which is bent in the direction of the base plate  51  and a portion which extends horizontally (parallel to the ground). This horizontal portion has two bores for receiving screw connections  48 . The screw connections  48  enable fixing to the connecting device  37 . The connecting device  37  is notable in that it provides a suspension device for the end fitting  38  of the insulator  31 . This suspension device is formed in that the one  39  at the end of the end fitting  38  can be inserted into a cutout  40  of the connecting device  37 . In this case, the fork  39  extensively encompasses the connecting device  37 , formed substantially as a flat metal piece, so that, when fixed in place accordingly by means of a screw  45  and a securing clip  46 , there are only very few movement options for the end fitting  38  with the fork  39  in the holder of the connecting device  37 . Better stability of the length of the isolating distance D is thus achieved in the prior art, even when wind loads act on the insulator  31 . The connecting device  37  furthermore has an eye  49  for grasping a mast suspension device  50 . 
       FIG. 6  shows an inventive connecting device  60  of a long-rod insulator  31 . The connecting device  60  has an end fitting, which, in one piece, contains the connecting device for mounting a further operating means and for suspension on a mast. To this end, the end fitting has a contact portion  61 , arranged approximately centrally, for mounting the additional operating means or a holding web for the arrester. The contact portion  61  has two bores  62 ,  63  for fixing a holding web in place. An eye  64  for the attachment of a mast suspension device is furthermore provided. A substantial advantage of this exemplary embodiment is that, in contrast to previous insulator fittings and connecting devices, degrees or freedom and therefore vibrations are no longer possible. The fork and the corresponding cutout in the known device according to  FIG. 5  are omitted. This saves on material and reduces costs. 
       FIG. 7  shows the inventive end fitting with the connecting device  60  in connection with the otherwise known components of the EGLA according to  FIGS. 4 and 5 . The same components are denoted by the same reference signs. The eye  64  of the connecting device is connected to a mast suspension device  65 .