Abstract:
A power circuit breaker includes an insertion rack which is arranged in a distribution unit and a lock system for locking the power circuit breaker in the insertion rack in a locking system. The locking system can be actuated by a drive mechanism, in particular by the switch shaft of the power circuit breaker.

Description:
[0001]     This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/DE2003/002885 which has an International filing date of Aug. 28, 2003, which designated the United States of America and which claims priority on German Patent Application number DE 102 51 002.4 filed Oct. 30, 2002, the entire contents of which are hereby incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The invention generally relates to a power circuit breaker having a withdrawable-part rack. In one example, it relates to one which can be arranged in a switchgear assembly by use of the withdrawable-part rack.  
       BACKGROUND OF THE INVENTION  
       [0003]     Power circuit breakers of the generic type are known. By arranging them in their withdrawable-part rack, they can be inserted or withdrawn in or from a switchgear assembly in a simple manner. In this case, significant importance is given to locking the power circuit breaker in its withdrawable-part rack.  
         [0004]     In particular in the case of power circuit breakers having a high short-circuit disconnection capacity, a force occurs, owing to the loop effect of the current path of the power circuit breaker or of the switchgear assembly, which acts on the power circuit breaker. This force is directed such that the power circuit breaker is forced out of its withdrawable-part rack.  
         [0005]     In particular in the case of high flowing currents (short-circuit currents), considerable forces acting on the power circuit breaker occur since the force acting rises with the square of the current. If in this case the power circuit breaker is not fixed in its withdrawable-part rack precisely in the line of action of this force, the power circuit breaker may be subjected to a torque owing to leverage. The result is that the power circuit breaker experiences a tipping movement which leads to a relative movement between the connection pieces of the switching contacts of the power circuit breaker and the contact laminations of the withdrawable-part rack.  
         [0006]     This relative movement may lead to a separation of the switching contacts from the contact laminations, with the result that arc formation cannot be ruled out. As a result of the high flowing currents, destruction of the power circuit breaker would be associated with this.  
         [0007]     It is known to latch the power circuit breaker with its withdrawable-part rack by way of a latching device. In this case, retaining systems are known which are actuated by an insertion shaft or an insertion drive for the purpose of inserting the power circuit breaker in the withdrawable-part rack. Such retaining systems, however, are typically of a complex design. Furthermore, a minimum amount of play is provided between the restraining elements of the retaining system and the withdrawable-part rack, since only a simultaneous movement between the power circuit breaker and the withdrawable-part rack and lifting-out of the restraining systems is possible.  
         [0008]     In addition, rigid systems are known, by which the insertion direction or the withdrawal direction of the power circuit breaker in or out of the withdrawable-part rack can be blocked. These systems have a relatively small, effective lever arm, such that the high forces which occur in particular in the case of a short-circuit cannot reliably be absorbed.  
         [0009]     DE 196 47 747 C1 discloses an insertable device carrier having a latching device. In this case, a latching rod is displaced at the same time owing to a rotation of an actuating shaft of a main breaker. The latching rod in turn displaces a blocking slide. The result is that latching of the device carrier takes place.  
         [0010]     As a result, single-point latching of the device carrier is achieved such that it is positioned. However, if high forces are acting owing to high currents flowing (short-circuit currents), the latching rod known from DE 196 47 747 C1 forms a lever arm such that a displacement of the device carrier. Accordingly, a power circuit breaker from the desired latched position cannot be ruled out. The point of engagement of the latching rod in a latching opening in a device floor in this case acts as a pivot in order that a deflection of the latching rod can take place.  
       SUMMARY OF THE INVENTION  
       [0011]     An embodiment of the invention includes an object of creating a power circuit breaker which can be latched safely in its withdrawable-part rack by way of a simple arrangement.  
         [0012]     According to an embodiment of the invention, an object may be achieved by a power circuit breaker. As a result of the fact that the latching device of the power circuit breaker can be operated by a switching drive, in particular by a switching shaft of the power circuit breaker, it is advantageously possible to link the closure of the switching contacts of the power circuit breaker with the latching of the power circuit breaker in the withdrawable-part rack. This operative connection, which is thus almost provided, between the closed switching contacts of the power circuit breaker and the latching of the power circuit breaker in the withdrawable-part rack makes it possible to apply a restraining force on the power circuit breaker which is matched to the switching position of the power circuit breaker, and which holds the power circuit breaker securely in the desired position, even in the event of high currents flowing.  
         [0013]     In particular, a situation is prevented in which the forces injected by the high currents force the connection pieces of the switching contacts and the contact laminations of the withdrawable-part rack apart from one another. The result is that the arc formation mentioned initially can be suppressed.  
         [0014]     In one preferred refinement of an embodiment of the invention, provision is made for the switching shaft to include at least one actuating element. This element is connected to the switching shaft such that it is fixed against rotation and by which the latching device can be brought into the latched position or the unlatched position. As a result, the actuation of the latching device is possible in a particularly simple manner.  
         [0015]     The switching shaft of the power circuit breaker in this case bears a gear or gear segment, which is arranged such that it is fixed against rotation, preferably outside of an exterior limiting structure. As a result, it is possible in a particularly simple manner to couple the switching movement of the contact arrangement to the actuation of the latching device. The switching shaft undergoes a rotary movement, which is at the same time used to actuate the latching device, for connection, i.e. for the purpose of closing the switching contacts, or for disconnection, i.e. for the purpose of opening the switching contacts, of the power circuit breaker.  
         [0016]     In particular if, in one further example refinement of an embodiment of the invention, the axially displaceable latching bolts have a toothed rod section which meshes with the actuating element. The rotary movement of the switching shaft can easily be converted into a lifting movement of the latching bolts. It is thus possible to lock the power circuit breaker in a reliable manner.  
         [0017]     In accordance with further refinements of embodiments of the invention, the actuating element can be operatively connected to the latching bolt via a crank arrangement, open or closed cam disks, cable pulls, Bowden cables or the like. Irrespective of the specific design of this operative connection, the rotary movement of the switching shaft can be transferred in a simple manner to the latching movement or unlatching movement of the latching device.  
         [0018]     Embodiments include a robust design requiring little or no maintenance. As a result, they are particularly suitable for being used in power circuit breakers which are subjected to relatively robust operating conditions.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     Further advantages, features and details of the invention will become evident from the description of illustrated example embodiments given hereinbelow and the accompanying drawings, which are given by way of illustration only and thus are not limitative of the present invention, wherein:  
         [0020]      FIG. 1  shows a schematic view of a power circuit breaker;  
         [0021]      FIG. 2  shows a schematic plan view of a first embodiment of a latching device of the power circuit breaker; and  
         [0022]      FIG. 3  shows a second embodiment of a latching device. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]      FIG. 1  shows a schematic illustration of a power circuit breaker  10 , for reasons of clarity details being omitted from the illustration. In accordance with the illustration, the power circuit breaker is, for example, a three-pole power breaker.  
         [0024]     The power circuit breaker  10  includes a switching shaft  12 , by which movable switching contacts of the power circuit breaker  10  can be guided towards fixed switching contacts (closed position) or away from the switching contacts (open position). For this purpose, the switching shaft  12  can be rotated about its longitudinal axis in a corresponding angular range by a drive arrangement (not shown).  
         [0025]     The power circuit breaker  10  can be arranged in a switchgear assembly (not shown) by way of a withdrawable-part rack  14  which is merely indicated.  
         [0026]     The switching shaft  12  is extended beyond lateral structural elements  16 , for example retaining and accommodating frames, and bears there, on both sides, a latching device which is given the overall designation  18 . The design and operation of the latching device  18  will be explained in more detail with reference to  FIG. 2 .  
         [0027]     The latching device  18  includes an actuating element  20 , which is arranged such that it is fixed against rotation on the switching shaft  12  and which interacts with a latching bolt  22 . The latching bolt  22  is arranged such that it can be displaced axially and is guided, for example by means of guide rollers  24 .  
         [0028]     The actuating element  20  is formed by a gear segment  26 , which has an associated toothed rod section  28  of the latching bolt  22 . The gear segment  26  and toothed rod section  28  are in meshing engagement with each other.  
         [0029]     The latching device  18  illustrated in  FIGS. 1 and 2  has the following operation:  
         [0030]     When the switching shaft  12  is actuated for the purpose of closing the switching contacts of the power circuit breaker  10 , the switching shaft is rotated about its axis of rotation  30 , as shown in the illustration in  FIG. 2  in the counterclockwise direction. As a result, the actuating element  20 , which is connected to the switching shaft  12  such that it is fixed against rotation, experiences an identical rotary movement. As a result of the fact that the actuating element  20  meshes with the latching bolt  22 , the latching bolt  22  experiences a lifting movement which is directed in the direction of the arrow  32 .  
         [0031]     As a result, the latching bolt  22  engages in a corresponding opening  34  in the withdrawable-part rack  14 . For the purpose of inserting the latching bolt  22  precisely in the opening  34 , the latching bolt  22  may have a conical tip  35 .  
         [0032]     It becomes apparent that the switching movement of the power circuit breaker  10  may be transferred in a simple manner to the actuation of the latching device  18  via the switching shaft  12 . Thus, when the power circuit breaker  10  is connected, the latching device  18  may be automatically moved over into the latched position. The power circuit breaker  10  is thus in any case secure during its connected state.  
         [0033]     In this case, a controlled movement of the latching device  18  takes place such that it is already latched before primary arcing contact of the power circuit breaker  10  is effective. This ensures that the locking has already reliably taken place even in this connected state of the power circuit breaker  10 .  
         [0034]     Unlatching of the latching device  18  takes place in analogous fashion by opening the power circuit breaker  10 . In this case, in turn the switching shaft  12  experiences an opposite rotary movement about the axis of rotation  30 , in accordance with the illustration in  FIG. 2 ), in the clockwise direction. The correspondingly resulting rotary movement of the actuating element  20  is transferred to the latching bolt  22 , with the result that the latching bolt  22  is lowered in opposition to the lifting movement  32 , with the result that the latching bolt  22  is moved out of engagement with the opening  34 .  
         [0035]     As indicated in  FIG. 2 , the actuating element  20  has associated with it a further latching bolt  22 ′ which is arranged diametrically opposite the latching bolt  22 . The design and operation of the latching bolt  22 ′ corresponds to those of the latching bolt  22 . Owing to the diametrically opposite arrangement, in the case of a lifting movement  32  of the latching bolt  22 , the latching bolt  22 ′ experiences a lifting movement  32 ′ in the opposite direction. This makes it possible at the same time to latch the power circuit breaker  10  both in an upper section and in a lower section of the withdrawable-part rack  14 .  
         [0036]     In the case of two latching devices  18  being provided, there is thus a total of four latching points. These latching points ensure secure positioning of the power circuit breaker  10  in its withdrawable-part rack which takes place even in the event of high currents and which is resistant to the action of high forces. Relative movements of connection pieces (not illustrated in any more detail) of the switching contacts and contact laminations of the withdrawable-part rack in relation to one another can thus be prevented.  
         [0037]      FIG. 3  shows a modified embodiment of the latching device  18 . In this case,  FIG. 3   a  shows the unlatched position, and  FIG. 3   b  shows the latched position. Identical parts to those in the preceding figures are provided with identical reference numerals and will not be explained again.  
         [0038]     In contrast to the exemplary embodiment shown in  FIGS. 1 and 2 , the actuating element  20  is in this case in the form of a crank arrangement  36 , which interacts with a corresponding link guide  38  of the latching bolts  22  and  22 ′, respectively. This also makes it possible, in a simple manner, for the rotary movement of the switching shaft  12  to be converted into the lifting movement  32  of the latching bolts  22  and  22 ′.  
         [0039]     The actuating element  20  has associated with it two diametrically opposite latching bolts  22  and  22 ′, respectively. Here too, an actuating element  20 , in the form of a twin-crank arrangement, interacts with link guides  38  of the in this case two latching bolts  22  and  22 ′.  
         [0040]     Exemplary embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.