Abstract:
A surge arrester includes an insulator having a first insulator end and an opposite second insulator end, at least one first electric arc electrode attached in the region of the first insulator end, at least one second electric arc electrode attached in the region of the second insulator end, a fixing element made of electrically non-conductive material for mounting the surge protector on an external support, and at least one dish-shaped element to which the first electric arc electrode is assigned and the dish side wall of which at least partially laterally encloses the first electric arc electrode. The fixing element is attached laterally to the dish side wall of the dish-shaped element.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a surge arrester having an insulator with first and second oppositely-lying insulator ends, at least one first electric arc electrode mounted in the region of the first insulator end, at least one second electric arc electrode mounted in the region of the second insulator end, a fixing element composed of an electrically non-conductive material for fitting the surge arrester to an external support and at least one dish-shaped element with which the first electric arc electrode is associated and the dish side wall of which at least partly laterally surrounds the first electric arc electrode. 
     A surge arrester of this type is known from European patent EP 0 966 080 B1. Said surge arrester comprises an insulator with a resistor element located therein. A lower electric arc electrode in the form of an electrode plate is mounted in the region of a lower insulator end of the insulator. An upper electric arc electrode is located in the region of an upper insulator end. Both the upper arc electrode and the lower arc electrode have a respective associated dish-shaped element, the dish side wall of which laterally surrounds the respective arc electrode at least in sections. In order to fit the surge arrester to an external support, an insulation clip is present which is screwed to the dish base below the lower dish-shaped element. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention is based on the problem of specifying a surge arrester which has as compact a design as possible. 
     This problem is solved according to the invention by a surge arrester having an insulator with first and second oppositely-lying insulator ends, at least one first electric arc electrode mounted in the region of the first insulator end, at least one second electric arc electrode mounted in the region of the second insulator end, a fixing element composed of an electrically non-conductive material for fitting the surge arrester to an external support and at least one dish-shaped element with which the first electric arc electrode is associated and the dish side wall of which at least partly laterally surrounds the first electric arc electrode. The fixing element is mounted laterally on the dish side wall of the dish-shaped element. Advantageous embodiments of the surge arrester according to the invention are specified in the sub claims. 
     Accordingly it is provided according to the invention that the fixing element is mounted laterally on the dish side wall of the dish-shaped element. A substantial advantage of the surge arrester according to the invention can be seen in that said surge arrester requires less space in the longitudinal direction. In contrast to the previously known surge arrester, this is because the fixing element for fixing the surge arrester to an external support is arranged not below the lower dish-shaped element but rather laterally on the dish side wall of the dish-shaped element. By means of this arrangement of the fixing element, a significant amount of space is saved, with the result that the surge arrester according to the invention is particularly compact. 
     In order to achieve a particularly solid connection between the fixing element and the dish-shaped element, it is considered to be advantageous for the fixing element and the dish-shaped element to be component parts of a single, one-piece retaining element which forms, with a first end section, the dish-shaped element for holding the first electric arc electrode and, with a second end section, the fixing element for fitting the surge arrester to an external support. A further advantage of a one-piece embodiment of fixing element and dish-shaped element is that the fitting effort when fitting the surge arrester is minimized; in this way, it is no longer necessary to fit the fixing element to the dish-shaped element separately since it is already a component part of one and the same component, namely the retaining element. 
     In reference to minimum manufacturing costs, it is considered to be advantageous for the one-piece retaining element to be a pressed part or an injection-molded part. Particularly preferably, the one-piece retaining element consists of plastic. 
     For a compact design of the surge arrester, it is moreover considered to be advantageous for the second electric arc electrode to be arranged in a second dish-shaped element, the dish side wall of which laterally surrounds the second arc electrode. 
     A through-hole is preferably present in the dish base of the first and/or second dish-shaped element, through which through-hole a contact element which is electrically connected to the respective electric arc electrode is routed. 
     In order to achieve good electrical insulation for the surge arrester, in particular for the protection of birds, it is considered to be advantageous for at least one protective cap to be present which is seated on the first dish-shaped element or the second dish-shaped element and forms a shock protector for the respective contact element. 
     To ensure particularly reliable shock protection, it is considered to be advantageous for a protective wall to be mounted on the dish base of the first and/or second dish-shaped element, which protective wall extends away from the dish base—in the opposite direction to the extent of the respective dish side wall—and forms, at least in sections, a lateral shock protector for the contact element routed through the through-hole in the dish base. 
     Preferably, the outer edge of the protective cap rests on the protective wall or is clamped thereon. In the case of such fixing of the protective cap on the protective wall, the protective wall performs a dual function: firstly, it is—as already explained—a lateral shock protector and secondly, at the same time, it serves for particularly secure and solid fixing of the protective cap, with the result that it is more difficult for animals, for example birds, to remove the protective cap. 
     In reference to particularly solid seating of the protective cap, it is considered to be advantageous for the protective cap to have an inner clamping section which is placed onto or clamped on to the contact element. 
     In order also to guarantee lateral shock protection when the protective cap has been removed, for example by birds, it is considered to be advantageous for the height of the protective wall to be at least as high as the section of the contact element which protrudes from the dish base of the dish-shaped element. 
     In order to achieve particularly solid seating of the protective cap, it is considered to be advantageous for the protective cap to have an inner clamping section, which is placed onto or clamped onto the contact element, and an outer clamping section, which is placed onto or clamped onto the protective wall. By providing two clamping sections, it is made particularly difficult for animals to remove the protective cap and to gain access to the covered electric contact element. 
     Furthermore, in reference to a particularly compact design of the surge arrester, it is considered to be advantageous for the protective wall and the protective cap to form a lateral connection channel which extends radially outward and enables an electric supply cable connected to the contact element to be routed out perpendicularly to the longitudinal direction of the surge arrester. By means of the lateral routing out of the electric supply cable, undesired extension of the surge arrester in the longitudinal direction of the insulator is advantageously avoided. 
     In order that animals, such as birds, for example, cannot gain access to the contact element through the lateral connection channel, it is considered to be advantageous for a rear wall to be present for closing the connection channel, which rear wall extends in the longitudinal direction of the surge arrester and closes off access to the edges of the connection channel. Preferably, the rear wall has a through-hole through which the electric supply cable is routed or can be routed. In other words, the rear wall is therefore used to securely cover the contact element as far as possible from all sides. 
     For solid seating of the rear wall, it is considered to be advantageous for said wall to be clamped in between the protective cap and the dish base. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The invention is explained in more detail below on the basis of an exemplary embodiment; in this case, in the figures, by way of example: 
         FIG. 1  shows an exemplary embodiment of a surge arrester according to the invention in an exploded diagram, 
         FIG. 2  shows the surge arrester shown in  FIG. 1  in the assembled state, 
         FIG. 3  shows the lower section of the surge arrester shown in  FIG. 1  in more detail, 
         FIG. 4  shows the upper part of the surge arrester shown in  FIG. 1  in a view diagonally from above, and 
         FIG. 5  shows the upper part of the surge arrester shown in  FIG. 1  in a view laterally from below. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     For reasons of clarity, the same reference signs are always used in the figures for identical or comparable components. 
     A surge arrester  10  which is equipped with an insulator  20  can be seen in  FIG. 1 . Inside the insulator  20  are one or more resistor elements—not shown in  FIG. 1 —which may, for example, be varistor elements. The function of the resistor element or elements is to enable a current flow in the event of a surge and therefore to enable the surge to be arrested. 
     A one-piece retaining element  30  is arranged in the region of the (first) insulator end  21 —the lower end in  FIG. 1 —of the insulator  20 , the first end section  31  of which retaining element is formed by a dish-shaped element  40 . The other, second end section  32  of the one-piece retaining element  30  forms a fixing element  50  for the surge protector  10  on an external support—not illustrated in more detail in  FIG. 1 . For this purpose, a fixing hole  51  is provided in the region of the second end section  32  or in the fixing element  50 , through which hole a fixing bolt can be routed for fitting. 
     The dish-shaped element  40  serves to hold a first lower arc electrode  60  and further lower arc electrodes  61 ,  62  and  63 . The lower arc electrodes  60 ,  61 ,  62  and  63  are inserted into the dish-shaped element  40  and are laterally surrounded by the dish side wall  41  of the dish-shaped element. The four arc electrodes  60  to  63  are electrically connected to a lower (first) contact element  70  which is electrically connected to the lower end—not shown in  FIG. 1 —of the resistor element contained within the insulator  20 . The lower contact element  70  extends with its lower end  71  past the arc electrodes  60 - 63 , through the lower dish base  42 , and is screwed together with a lower nut  80 . 
     It can clearly be seen in  FIG. 1  that the fixing element  50  is mounted laterally on the dish-shaped element  40  of the single-piece retaining element  30 . The effect achieved by the arrangement of the fixing element  50  on the side (side wall) of the dish-shaped element  40  is that the length of the surge arrester  10 —as seen in the longitudinal direction of the insulator  20 —is kept as small as possible. 
     It can furthermore be seen in  FIG. 1  that a second dish-shaped element  100  is arranged in the region of an upper (second) insulator end  22  of the insulator  20 , the shaping of which second dish-shaped element differs from the dish-shaped element  40  at the lower insulator end  21  of the surge arrester  10 : thus, inter alia, no fixing element  50  is mounted on the dish side wall. 
     The lower insulator end  21  and the upper insulator end  22  are isolated from one another by the insulator body and the resistor elements located therein. 
     On the dish base  101  of the second dish-shaped element  100 , there is a protective wall  102  which extends upward from the dish base  101  in the longitudinal direction of the insulator  20 . The direction of extent of the protective wall  102  is therefore opposite to the direction of extent of the dish side wall  103 , which extends downward in  FIG. 1 , that is to say toward the lower insulator end  21  of the insulator  20 . 
     In the region of the upper insulator end  22 , a second contact element  110  can furthermore be seen, the upper end  111  of which is pushed through the dish base  101  of the second dish-shaped element  100 ; this is explained in even more detail below in connection with  FIGS. 4 and 5 . 
     Furthermore, an upper arc electrode  120  (also called “second” arc electrode) can be seen in  FIG. 1 , which upper arc electrode is arranged inside the dish-shaped element  100  and laterally surrounded by the dish side wall  103  of the dish-shaped element  100 . Moreover, further upper arc electrodes  121 ,  122  and  123  can be seen, which are likewise held by the dish-shaped element  100  and laterally surrounded by the dish side wall  103 . 
     In order to cover the upper end  111  of the second contact element  110 , the surge arrester  10  has a protective cap  140  which is seated on the protective wall  102  and on the upper end  111 ; this is explained in detail below in connection with  FIGS. 4 and 5 . 
       FIG. 2  shows the surge arrester  10  shown in  FIG. 1  in the assembled state. It can clearly be seen that the retaining element  30  is in one piece and the fixing element  50  is attached or cast laterally on the dish side wall  41  of the dish-shaped element  40  in one piece. The retaining element  30  may be, for example, a pressed part or an injection-molded part. 
     Furthermore, the protective cap  140  can be seen in  FIG. 2 , the outer edge  141  of said protective cap being seated on the protective wall  102  and clamped thereon. The outer edge  141  forms an outer clamping section which is placed onto or clamped onto the protective wall  102 . In addition, a rear wall  150 , the function of which is explained in more detail below, can be seen. 
       FIG. 3  shows the lower region of the surge arrester  10  in even more detail. The one-piece retaining element  30  can be seen along with the dish-shaped element  40  and the fixing element  50  which is mounted laterally on the dish side wall  41  and by means of which the retaining element  30  and hence the surge arrester  10  as a whole can be fixed to an external support. 
       FIG. 4  illustrates in more detail the upper region of the surge arrester  10 . It can be seen that the upper section  112  of the second contact element  110  is routed through an opening in the dish base  101  and protrudes from the dish base  101 . In order to ensure shock protection, the protective wall  102  is provided around the section  112  of the second contact element  110 , the height H of said protective wall being selected such that the protective wall  102  is higher than the height h of the section  112  of the second contact element  110 . 
     Therefore H&gt;h applies. 
     In order to improve the shock protection even further, the protective cap  140  is provided, which closes off the upper opening region  102   a , which is defined by the upper edge of the protective wall  102 . The outer edge  141  of the protective cap  140  is in this case shaped such that the protective cap  140  is firmly clamped by the upper edge of the protective wall  102 . The protective cap  140  is therefore retained on the protective wall  102  in a clamping manner. 
     In order to ensure an electrical connection to the second contact element  110 , the protective wall  102  and the protective cap  140  are shaped such that a lateral connection channel  160  is formed. By means of this lateral connection channel  160 , an electric supply cable—not shown in more detail in  FIG. 4 —can be routed to the second contact element  110  perpendicularly to the longitudinal direction of the surge arrester  10  in order to ensure an electrical connection to the exterior. 
     In order to ensure shock protection even in the region of the lateral connection channel  160 , the rear wall  150  is provided, which closes off the edges of the electric connection channel  160  in the longitudinal direction of the surge arrester  10 . The rear wall  150  is provided with a through-hole  151 , through which the electric supply cable, which has already been mentioned, for making electrical contact with the second contact element  110  can be routed. In  FIG. 5 , the upper region of the surge arrester  10  is shown in even more detail. The lower region of the protective cap  140  can be seen. It can be seen that the protective cap  140  has an inner clamping section  143 , the inner contour of which matches the outer contour of the second contact element  110 . This makes it possible for the protective cap  140  to be pushed onto the contact element  110  in a clamping manner, which means that the protective cap  140  is held by the second contact element  110  in a clamping manner. Said clamp connection assists the clamp connection provided by the outer edge  141  of the protective cap  140  as soon as the outer edge  141  is placed onto the protective wall  102 . 
       FIG. 5  also shows the rear wall  150  by means of which it is made more difficult to reach in laterally through the lateral connection channel  160  toward the contact element  110 . 
     In summary, a very compact design is achieved for the surge arrester  10  shown in  FIGS. 1 to 5  in that the fixing element  50  and the lower dish-shaped element  40  are formed by a one-piece or one-part retaining element  30 , wherein the fixing element  50  is laterally mounted or cast or molded onto the lateral dish side wall  41  of the dish-shaped element  40 . 
     Furthermore, the surge arrester  10  shown in  FIGS. 1 to 5  is distinguished in that a dish-shaped element  100  is provided in the region of the upper end of the surge arrester  10 , said dish-shaped element having two walls, namely the upper protective wall  102 , which provides lateral shock protection for the second contact element  110 , and the dish side wall  103 , which serves to hold the second arc electrode  120 . The dish side wall  103  and the protective wall  102  are one-piece component parts of the dish-shaped element, with the result that the second upper dish-shaped element  100  can be formed, for example, by a pressed part or an injection-molded part.