Abstract:
A modular cost-effective drive system for electrical switching devices of medium-voltage installations is specified. The drive system, by the addition or omission of individual components, can be used both as a three-position disconnector with a snap-action or storage drive function and as a two-position circuit breaker which can also be expanded by a brief interruption function.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a drive system for electrical switching devices for medium-voltage switchgear assemblies with a different function, which has drive springs which are loaded via operating shafts and act on an output shaft which is connected to the switching element of a switching device. 
     Switching devices with a different function, for example circuit breakers, load switch disconnectors, switch disconnectors or grounding devices are used in medium-voltage switchgear assemblies in the form of three-position and two-position switches with the functions ON, OFF and GROUND or OFF and ON and optionally a brief interruption function OFF-ON-OFF and are equipped with respectively individually designed, different drives, depending on their function and the respective requirements. The production effort and cost for the drives, which are designed differently to correspond to the respective switch type, are correspondingly high. By way of example, DE 3239839 C1 describes a drive for an electrical three-position switch, which comprises both a snap-action drive assembly and a storage drive assembly. In the case of the snap-action drive, a bending spring can be loaded such that the load can be suddenly removed from it and a switching shaft together with a crank lever can rotate from an OFF mid-position in the ON direction, and in the other direction to GROUND and vice versa. The storage drive assembly which, in addition to the crank lever, has a multiplicity of further components, is combined with the snap-action drive assembly such that, when a fuse blows or the signal from a shunt release occurs, switching takes place from ON to OFF via the storage drive assembly, while only the snap-action drive assembly operates for direct drive operation. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention is based on the object of specifying a drive of modular design for electrical switching devices for medium-voltage assemblies which can be used for switching devices with different tasks, with minor design modifications and therefore with little production effort and cost. 
     According to the invention, the object is achieved by a drive system which can be upgraded in a modular form. 
     The fundamental idea of the invention is to provide a drive system of modular design which can be modified by the addition of individual additional components or the omission of individual components, that is to say with little design effort and cost, such that it can be used both for three-position switch disconnectors with a snap-action drive or storage drive function and for two-position circuit breakers with or without a brief interruption capability (OFF-ON-OFF). 
     In comparison to the first drive variant with a snap-action drive function, which has blocking catches for tripping via cam disks of a first drive spring, for a three-position switch, a second drive variant with a storage drive function for changing between ON and OFF has a second drive spring as well as additional first and second storage drive blocking catches, which can be tripped manually via tripping half-shafts and correspond to the first and the second drive springs. As the basis for all modifications, the drive system has a first operating shaft which is connected to a first drive spring and is connected via an output shaft to a switching element of the switching device, as well as a second operating shaft, which is connected to the first operating shaft via gearwheels such that they engage. 
     In the embodiment as a three-position disconnector with a snap-action function, the first drive spring has an associated first blocking catch for switching the OFF and GROUNDED position and a second blocking catch for switching the ON and OFF position. 
     In order to achieve the ON and OFF position of the switching element via a storage drive, the second operating shaft may have an associated second drive spring and a second storage blocking catch, which corresponds thereto, in combination with a second tripping half-shaft, and the first drive spring is associated with a first storage blocking catch in combination with a first tripping half-shaft. In the case of a three-position disconnector, the switching between the OFF and GROUNDED position also in this case takes place as a snap-action drive via the first drive spring and the first blocking catch. When used as a two-position circuit breaker, the first and second blocking catches are in this case omitted. 
     The two-position circuit breaker may additionally have an OFF-ON-OFF brief interruption function, by arranging a clutch between the output shaft and the switching device. The clutch comprises first and second clutch disks, which are connected via a storage blocking catch. The first clutch disk, which is held temporarily on the second tripping half-shaft via the storage blocking catch, is connected to an additional drive spring in order to achieve the OFF position. 
     One exemplary embodiment of the invention will be explained in more detail with reference to the drawing. In the drawing, in each case illustrated in perspective as front and rear views: 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIGS. 1   a  and  1   b  show a first drive variant for a three-position switch disconnector with a snap-action drive function between the positions ON, OFF and GROUNDED; 
         FIGS. 2   a  and  2   b  show a second drive variant for a three-position switch disconnector with a storage drive function between the positions ON and OFF, and a snap-action drive function for changing between OFF and GROUNDED, according to the drive variant shown in  FIG. 1 ; 
         FIG. 3  shows a third drive variant for a two-position circuit breaker with a storage drive function according to the drive variant shown in  FIG. 2  for changing between OFF and ON; and 
         FIGS. 4   a ,  4   b  and  4   c  show a fourth drive variant, in which the drive for the two-position circuit breaker as shown in  FIG. 3  has had a brief interruption function OFF-ON-OFF added to it. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The drive, which is in modular form for four switch variants, is in each case mounted between two mounting plates  1  and  2 . 
     The first drive variant as shown in  FIG. 1  is intended for a three-position switch disconnector with the switch positions OFF, ON and GROUNDED. The change between the three switch positions takes place via a snap-action drive function, with a first drive spring  6 , which is in the form of a rotary spring in this case, being loaded manually via a first or second operating shaft  4 ,  5  with the aid of a control lever or else by motor force, and having the load removed from it again by releasing a first or second blocking catch  8 ,  9 , which is tripped via cam disks  21 , in order to move the switching element of the switching device to the respective switch position via an output shaft  18 , which is driven by the first drive spring  6 , and an output lever  3  which is connected thereto. The first operating shaft  4  and the second operating shaft  5  are connected to one another via gearwheels  19 ,  20 . The second operating shaft  5  is used for the disconnector function. A rotary movement of the second operating shaft  5  to the right loads the first drive spring  6  in order to achieve the ON switch position, and a rotary movement to the left results in the OFF switch position. The energy which is produced by the rotary movement in the first drive spring  6  is released by the second blocking catch  9  and then acts on the output shaft  18  and, in the end, on the output lever  3  which is connected to a switching element. The first operating shaft  4  is intended for the grounding device function of the switching element, in that the first drive spring  6  is loaded by rotation of the first operating shaft  4  to the right in order to achieve the GROUNDED switch position, and by rotation of the first operating shaft  4  to the left in order to achieve the OFF switch position. The release of the spring load for switching from OFF to GROUNDED and back is produced by releasing the first blocking catch  8 . 
     According to the second drive variant, as illustrated in  FIG. 2 , for a three-position switch disconnector (ON, OFF, GROUNDED), the change between the OFF and the GROUNDED switch positions—as in the case of the first drive variant—still takes place as a snap-action drive by loading the first drive spring  6  by means of the first operating shaft  4 , and releasing it by tripping the first blocking catch  8 . In this case, however, the change between the ON and the OFF position takes place by storage tripping of the first drive spring  6  and an additional second drive spring  7 . The second operating shaft  5  has an associated second drive spring  7 , which acts as a storage drive spring for switching to OFF. The first drive spring  6  is operatively connected to a first storage drive blocking catch  10 , which is coupled to a first tripping half-shaft  13 , and the second drive spring  7  is operatively connected to a second storage drive blocking catch  11 , which is coupled to a second tripping half-shaft  14 . In order to switch to ON, the tripping half-shaft  13  is rotated by pushing a button, as a result of which the first storage drive blocking catch  10  and therefore the energy stored in the loaded first drive spring  6  are released, and can act on the output shaft  18  for switching on. To switch to OFF, the second storage drive blocking catch  11  and therefore the energy in the loaded second drive spring  7  are released by rotation of the second half-shaft  14 , in order to move the switching element to the OFF position, via the output shaft  18  and the output lever  3 . 
     The third drive variant, illustrated in  FIG. 3 , with minor modifications in comparison to the second embodiment variant, to be precise by the omission of the cam disk with the first and second blocking catches  8  and  9 , is designed only for a two-position circuit breaker. The change between the ON and the OFF position and vice versa takes place as described with reference to  FIG. 2 . The “loading” function of the first drive spring  6  for switching to GROUNDED and back is not required, and the parts which are required for this purpose are not provided in this drive variant. 
     The fourth drive variant, as shown in  FIGS. 4   a  to  4   c , is intended for a two-position circuit breaker as shown in  FIG. 3  which, however, is additionally formed with a first and a second clutch disk  15 ,  16 , as well as an additional drive spring  17 , for storage of an OFF-ON-OFF switching sequence for brief interruption by renewed loading of the first drive spring  6  after switching on (ON). The first, inner clutch disk  15  is connected to the output shaft  18  and to the first drive spring  6 , which is provided for switching on, and the second, outer clutch disk  16  is coupled to the output lever  3 , which is connected to the switching device. Rotation of the first tripping half-shaft  13  releases the first storage drive catch  10  and therefore the loaded first drive spring  6 . The free energy is partially transmitted via the first, inner clutch disk  15  to the output shaft  18  and therefore to the switching device for the ON switching process, while a further part of it is at the same time used to load the additional drive spring  17 . At the end of the ON switching process, the additional drive spring  17 , which is provided for switching to OFF, is held in the storage position for switching to OFF by means of a jointly rotating third storage blocking catch  12 . The third storage blocking catch  12  and therefore the additional drive spring  17  can now be released by rotation of the second tripping half-shaft  14 , in order to switch to OFF, or the first drive spring  6  can be loaded once again, blocked by the first storage blocking catch  10 , and held in the storage position. Switching off takes place by means of the jointly rotating third storage blocking catch  12 , which fixes the inner and the outer clutch disks  15 ,  16  with respect to one another. Since the additional drive spring  17  acts on the outer, second clutch disk  16 , it is possible to switch to OFF without influencing the first drive spring  6 . After loading of the first drive spring  6  with the switching device in the ON state, the OFF-ON-OFF switching sequence which is required for brief interruption can be carried out without having to supply energy once again from the outside. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Mounting plate 
           2  Mounting plate 
           3  Output lever 
           4  First operating shaft 
           5  Second operating shaft 
           6  First drive spring 
           7  Second drive spring 
           8  First blocking catch 
           9  Second blocking catch 
           10  First storage drive blocking catch 
           11  Second storage drive blocking catch 
           12  Jointly rotating storage blocking catch 
           13  First tripping half-shaft 
           14  Second tripping half-shaft 
           15  First, inner clutch disk 
           16  Second, outer clutch disk 
           17  Additional drive spring 
           18  Output shaft 
           19  Gearwheel 
           20  Gearwheel 
           21  Cam disk