Abstract:
The invention relates to a multipole fused switch arrangement for busbar systems having at least two fused switch units ( 10 ) which each holds a fuse link ( 20 ), with the fused switch units ( 10 ) having a mounting and contact apparatus ( 11 ) for a busbar, and having a switching apparatus for closing and interrupting the circuit of all the switched fuse units, with the fused switch arrangement comprising a combined switching and blocking apparatus ( 30 ), having a switching lever ( 40 ), an operating arrangement ( 60 ), a blocking apparatus ( 70 ) for each fused switch unit ( 10 ), and a locking apparatus ( 80 ).

Description:
This application is an application filed under 35 U.S.C. Sec. 371 as a national stage of international application PCT/EP00/07484, which was filed Aug. 2, 2000. 

   TECHNICAL FIELD 
   The invention relates to a multipole fused switch arrangement for busbar systems having at least two fused switch units which each holds a fuse link, with the fused switch units having a mounting and contact apparatus for a busbar, and having a switching apparatus for closing and interrupting the circuit of all the switched fuse units. 
   BACKGROUND OF THE INVENTION 
   Such fused switch arrangements are used in particular for protecting three-phase circuits, in which case three-pole fused switch arrangements are required. 
   Since such fused switch arrangements are also operated by those not skilled in the art, it has frequently been found to be a problem that incorrect operations even on the fused switch arrangement have led to damage to the appliances. 
   SUMMARY OF THE INVENTION 
   Accordingly, one object of the invention is to provide a multipole fused switch arrangement which is simple to operate and which minimizes the risk of incorrect operations by untrained personnel. 
   The object is achieved by a multipole fused switch arrangement according to the invention. 
   According to the invention, the fused switch arrangement comprises a combined switching and blocking apparatus. 
   The combined switching and blocking apparatus has a switching lever, which can be switched to and fro between a switched-on position and a switched-off position, an operating arrangement for switching switching links of the fused switch units, in which case the operating apparatus can be switched to and fro between a contact position and an interrupted position, a blocking apparatus for each fused switch unit for blocking the operating arrangement in the interrupted position, and a locking apparatus for locking the fuse link in an operating position, in which case the locking apparatus can be switched to and fro between a locked position and an isolating position. 
   The locking apparatus is coupled to the switching lever such that it is always in the locked position when the switching lever is in the switched-on position, and which, conversely, is in the isolating position when the switching lever is in the switched-off position. The operating arrangement is furthermore coupled to the switching lever such that it is always in the interrupted position when the switching lever is in its switched-off position. Further coupling between the operating arrangement and switching lever is possible, but not necessary. 
   The blocking apparatus blocks the operating arrangement in the interrupted position when one of the fuse links from the fused switch arrangement is not in its operating position, that is to say it has been completely removed from the fused switch arrangement, or has been at least partially withdrawn from its operating position. 
   The multipole fused switch arrangement according to the invention carries out two major protection functions. Firstly, it prevents the circuit of the fused switch arrangement from being closed via the switching links when the fuse links are not all in their operating position, and the fused switch arrangement is thus no longer in a ready to operate state. Secondly, it makes it impossible to remove fuse links when the fused switch arrangement is switched on, or to move them from their operating position, without previously having interrupted the circuit, so that the fuse links can be replaced only when no current is flowing and no voltage is applied. This double protection function reliably precludes incorrect operations and prevents damage to the elements of the fused switch arrangement, in particular of the contacts, for example as a result of switching arcs and spark flashovers. 
   In one preferred embodiment, the operating arrangement has a pushrod for each fused switch unit, with the pushrods being rigidly connected to one another and each pushrod resting on spring-loaded switching links via which the circuit of the fused switch unit is closed and interrupted. This ensures that all the circuits in all the fused switch units are interrupted even if only one of the pushrods is blocked in its interrupted position, since the associated fuse link is not in its operating position. 
   The operating arrangement can be coupled directly or indirectly to the switching lever in various ways. The coupling is preferably provided via a switching rod which is guided in a recess in the switching lever. The operating arrangement and the switching lever are coupled on only one side, that is to say only switching of the switching lever from the switched-on position to the switched-off position results in force being exerted on the operating arrangement via the switching rod, while there is no direct coupling between the switching rod and the operating arrangement when the switching lever is switched from the switched-off position to the switched-on position. Thus, although the switching lever can also be moved to the switched-on position when the operating arrangement is blocked in its interrupted position, no force is exerted, however, by the switching rod or the switching lever on the operating arrangement. This prevents loading or damage, in particular to the blocking apparatus. At the same time, this ensures that the circuit cannot be closed inadvertently by forceful operation of the switching lever while at the same time destroying the blocking apparatus. 
   The operating arrangement is preferably prestressed in its contact position by at least one spring apparatus, so that the operating arrangements are automatically located in their contact position when, firstly, all the fuse links are in their operating position and the blocking apparatus is in consequence not acting on the operating arrangement, and when the operating lever is in its switched-on position. 
   Each blocking apparatus is advantageously prestressed by a spring apparatus in a position which blocks the operating arrangement in its interrupted position, so that the operating arrangement is released only when one fuse link is in its operating position, as a result of which the blocking apparatus is moved against the force of the spring effect to a position in which the blocking apparatus and the operating arrangement do not influence one another. The blocking apparatus is automatically moved by the spring apparatus to its blocking position as soon as one fuse link is removed from its operating position, although, owing to the locking apparatus, this can occur only if the switching lever is in its switched-off position, and the operating arrangement is thus in its interrupted position. 
   When it is in its blocking position, the blocking apparatus advantageously engages in an opening in the operating arrangement, so that the blocking apparatus prevents any movement of the operating arrangement. 
   Depending on the configuration of the individual fused switch units, the fuse links are inserted directly into the fused switch unit, or fuse plugs are used to hold the fuse links in the fused switch units. 
   Accordingly, a locking apparatus can be provided which acts directly on the fuse link, but locking apparatuses are preferably provided which do not act directly on the fuse link, but which engage with a latching element on a fuse plug when in their locked position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the invention will become particularly clear from the attached schematic drawings, in which: 
       FIG. 1  shows a cross-sectional view of one embodiment of a three-pole fused switch arrangement, with the switching lever being in a switched-on position and the fused switch arrangement being ready to operate; 
       FIG. 2  shows a detail of the fused switch arrangement shown in  FIG. 1 , with the switching lever being in a switched-off position; 
       FIG. 3  shows the detail shown in  FIG. 2 , but with the fuse link having been removed; and 
       FIG. 4  shows the details shown in  FIGS. 2 and 3 , but with the switching lever having been removed to the switched-on position after removal of the fuse link. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a fused switch arrangement having three fused switch units  10 , into each of which a fuse plug  25  with a fuse link  20  is inserted. 
   Each fused switch unit  10  is mounted on a busbar  90  by means of a surrounding spring  95 . 
   The switching and blocking apparatus according to the invention comprises, in the embodiment shown in  FIG. 1 , a switching lever  40 , a spring-loaded switching rod  50 , an operating apparatus  60  which in each case comprises one pushrod  61  per fused switch unit  10 , a spring-loaded blocking apparatus  70 , and a likewise spring-loaded locking apparatus  80 . The spring  52  of the switching rod  50  has a considerably greater spring constant than the springs  62  in the operating apparatus and the springs  81  in the locking apparatus, which have approximately the same spring constants. The springs  71  in the blocking apparatus  70  have the lowest spring constant in the switching and blocking apparatus. 
   When the fused switch arrangement is in the working position shown in  FIG. 1 , the switching lever  40  is in the switched-on position. The switching lever  40  has a recess  41 , in which one end of the switching rod  50  is guided. The other end of the switching rod  50  is seated in a bearing  51  in the fused switch arrangement. 
   The operating arrangement  60  is prestressed in its contact position indirectly via three springs  62 , which are positioned between the housing of the fused switch arrangement and switching links  12 . The switching links  12  thus bridge an interruption in a bottom contact  30 , which makes contact with a lower contact  21  of the fuse link  20 , so that the contact is produced between the fuse link  20  and the busbar  90 . 
   The operating arrangement  60  is in this case deflected so far in the direction of the switching rod  50  that the pushrod  61  on the left in the drawing rests on the switching rod  50 . 
   Each upper contact  22  of the fuse link  20  makes contact with a tapping contact  14 , so that the circuit is closed via the tapping contact  14 , the upper contact  22  and the lower contact  21  of the fuse link  20 , the bottom contact  13 , the switching link  12 , the extension of the interrupted bottom contact  13  and the busbar  19 . 
   The fuse link  20  is always pressed by force from a spring  26  in the fuse plug  25  against the bottom contact  13 , thus ensuring a reliable contact. 
   The locking apparatus is pressed by the formed-out region  43  of the switching lever  40  into an opening (which is used as a latching element  27 ) in the fuse plug  25 , so that the fuse plug  25  is fixed, together with the fuse link  20 , in its operating position. The locking apparatus  80  is formed as one part for all the fused switch units and is prestressed by means of a spring apparatus  81  against the formed-out region  43  of the switching lever  40 . 
   Individual fused switch units and their assemblies are identical, and it should once again be mentioned that both the locking apparatus  80  and the operating arrangement  60  are formed as one part for all the fused switch units, so that the individual elements can thus move only together, and no relative movement is possible, for example between the pushrod  61 . In contrast, the blocking apparatuses  70  are autonomous assemblies, which are separate from one another, in each fused switch unit  10 . 
   The method of operation of the switching and blocking apparatus  30  according to the invention is clear from the further  FIGS. 2  to  4 , which, for simplicity, show only a detail of the embodiments. 
   In  FIG. 2 , the switching lever  40  has been moved from its switched-on position to its switched-off position. The locking apparatus  80 , which is prestressed against the switching lever  40  by means of the spring  81 , has been moved to the left in the figure, after passing over a step  44  (which is introduced in the switching lever  40 ) in the switching lever  40 , so that the interlocking element  82  no longer engages with the opening  27  in the fuse plug  25 . The fuse plug  25 , together with the fuse link  20 , is thus no longer locked in its operating position. 
   The switching of the switching lever  40  to its switched-off position results in the switching rod  50  pivoting to the right in its bearing  51  and in the recess  42 , as a result of which the operating arrangement  60  is forced via the pushrod  61  to its interrupted position, in which the switching link  12  is lifted off the bottom contact  13 . The circuit is thus interrupted at the bottom contact  13 . 
   Since the fuse plug  25  is still in its operating position and presses against a protrusion on the blocking apparatus, the blocking apparatus  70  is still held in a non-blocking position against the influence of its spring apparatus  71 . 
   Subject to the precondition that all the other fused switch units (which are not shown in FIG.  2 ), are in analogous positions, the switching lever  40  can be moved back to its switched-on position, as a result of which the fuse plugs  25  are automatically locked by the locking apparatus  80 . Since the operating arrangement  60  is not blocked, it is pushed to the left in the drawing together with the switching link  12  by means of the spring apparatus  62 , as a result of which the switching link  12  makes contact with the interrupted bottom contact  13 , and closes the circuit. 
     FIG. 3  shows the fused switch arrangement shown in  FIG. 2 , but with the fuse plug  25  together with the fuse link  20  having been removed from the fused switch unit  10 . In order to remove the fuse plug  25  from the fused switch unit, it must be pushed slightly to the left in the figure, in order that the latching element  16  of the fuse plug  25  can be moved over the projection  15  of the housing of the fused switch arrangement. 
   The locking apparatus  80  is, as already explained in conjunction with  FIG. 2 , no longer engaged with the fuse plug  25 , so that the locking apparatus  80  does not prevent removal of the fuse plug  25  and of the fuse link  20 . 
   Once the fuse plug  25  is no longer pressing downwards onto the protrusion on the blocking element  70 , the blocking apparatus  70  is moved upwards in the drawing by means of its spring  71 , so that parts of the blocking apparatus  70  extend into an opening  63  in the pushrod  61  of the operating arrangement  60 , blocking it. 
   As is shown in  FIG. 4 , although the switching lever  40  can be moved to its switched-on position, this results, however, in the switching rod  50  also being pivoted to the switched-on position. The pushrod  61  and the mounting arrangement  60  do not follow the movement of the switching rod  50  since the blocking apparatus  70  is engaged in the opening  63  in the pushrod  61 . Since the switching rod  50  and the pushrod  61  are not firmly connected to one another, movement of the switching lever does not exert any force on the pushrod  61  or on the blocking apparatus  70 , either. The pushrod  61  and the blocking apparatus  60  are still blocked, so that the switching link  12  is also held at a distance from the bottom contact  13 , against the spring force of the spring  62 , by the pushrod  61 . Thus, as designed, the circuit is still interrupted, as before. 
   Merely for the sake of completeness, it should be noted that the integral, rigid operating arrangement  60  means that the switching links  12  of the other fused switch units  10  are also held by the corresponding pushrods  61  at a distance from the associated bottom contact  13 , even if the fuse plug  25  has not been removed from these fused switch units  10  and the corresponding pushrod  61  is in consequence not autonomously blocked by the separate blocking apparatus  70 . 
   Since the switching rod  50  and the pushrod  61  are not firmly connected to one another this prevents careless operating personnel from being able to cause damage to the fused switch arrangement when the operating arrangement  60  is blocked by one of the blocking apparatuses  70 . 
   Finally, it should be mentioned that, of course, modifications can be carried out to the specific refinements of this embodiment without departing from the subject matter of the invention. In particular, fuse links without fuse plugs can be inserted directly into the fused switch units, and different types of fuse, for example screw-in fuses, may be used instead of plug-in fuses, or a different refinement of the switching lever or of the recess with the dead point may be chosen for switching which is essentially; independent of manual switching. 
   Furthermore, it should be mentioned that the drawings are only schematic and, in particular, no restrictions with regard to dimensions and sizes can be derived from the drawings.