Abstract:
A switching device for an electrical switchgear assembly for power distribution includes a grounding function unit including a first moving control element selectably moveable to a first manual operation position and an isolation function unit including a second moving control element selectably to a second manual operation position. The grounding function unit is selectable to a manual operation state by moving the first moving control element to the first manual operation position, and the isolation function unit function unit is selectable to a manual operation state by moving the second moving control element to the second manual operation position. When the manual operation state is selected for one of the grounding and isolation function units, selection of the other of the grounding and isolation functional units to the manual operation state is blocked by a respective one of the first and second moving control elements.

Description:
This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/EP2007/003663, filed on Apr. 26, 2007, which claims priority to German Patent Application No. DE 10 2006 024 007.3, filed on May 23, 2006. The International Application was published in German on Nov. 29, 2007 as WO 2007/134692 under PCT Article 21(2). 
     The present invention relates to a switching device for an electrical switchgear assembly, in particular for energy distribution. 
     BACKGROUND 
     Electrical switchgear assemblies for power distribution have an application-specific combination of different switching devices, also including isolating and grounding switches. Modern switchgear assemblies in this case combine the functions of isolation and grounding, in which a contact system can be moved to three appropriate positions. A switchgear assembly such as this has two function units—an isolator and a grounder. A three-position drive is required for this purpose. Manual operation of the switchgear assembly is envisaged for emergency operation. 
     Electrical switchgear assemblies for power distribution are known, for example, from the document EP 1 569 254. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is to specify a switching device for an electrical switchgear assembly for power distribution, which complies with safety requirements for switchgear assemblies for high-current applications, and has a high safety level with regard to control errors. 
     According to a first preferred embodiment, a switching device is specified for an electrical switchgear assembly for power distribution which comprises a first function unit for the function of grounding and a second function unit for the function of isolation, wherein manual operation can be selected for at least one of the two function units. When manual operation is selected for the first function unit, the selection of manual operation for the second function unit is blocked by a moving control element of this function unit. When manual operation of the second function unit is selected, the selection of manual operation of the first function unit is blocked by a moving control element of this function unit. 
     The moving control element of each function unit can be set to the following operating positions:
     A)(or D)) manual operation position,   B)(or E)) neutral position, in which the switchgear assembly is operated electrically,   C)(or F)) blocked position, in which the function unit is blocked, in which case neither electrical operation nor any manual change to the status of the switching device is possible.   

     The positions B) and C) of the two control elements can be selected independently of one another. In positions B) and C), the moving control elements do not block one another. In the latching position A) of a control element, the gate of this control element blocks the selection of the latching position A) of the other control element. 
     The mutual blocking of the selection of manual operation contributes to the safety function during manual operation of the drive. 
     For safety reasons, the manual operation may be equipped with at least one safety element, that is to say with an electrical circuit which allows manual operation. 
     Depending on the switching state of the switchgear assembly, release of the electrically operated blocking element may be separated for the ground and isolation side. 
     For this purpose, the switchgear assembly preferably comprises an electrically operated blocking element, by means of which the moving control element is locked for switching to the manual operation position when manual operation is not allowed. If an attempt is made to select manual operation, for example for the isolator side, safety information relating to whether manual operation is allowed is checked. If manual operation is allowed, for example for the isolator side, the electrically operated blocking element is pulled in, thus unlocking the moving control element. 
     The moving control element, for example on the isolator side, can now be moved to the actual position for manual operation A) or D). This releases an opening for insertion of an auxiliary element, for example a hand crank. At the same time, the geometric shape and arrangement of the control elements with respect to one another prevents that side of the switching device which has not been released, for example the grounder side, being able to be moved to the position A) or D). 
     When manual operation is not allowed, the electrically operated blocking element assumes a first position in which the movement of the moving control element of the two function units to the manual operation position is prevented. When manual operation is allowed, the electrically operated blocking element is moved by an electrical drive to a second position in which the moving control element is unlocked. 
     According to a second preferred embodiment, a switching device is specified for an electrical switchgear assembly for power distribution, which comprises a first function unit for the function of grounding, a second function unit for the function of isolation, and an electrically operated blocking element. Manual operation of both function units can be selected. Each function unit has a moving control element which, when manual operation is not allowed, is locked by means of the electrically operated blocking element for switching to the manual operation position. If an attempt is made to select manual operation, safety information relating to whether manual operation is allowed is checked. If manual operation is allowed, the electrically operated blocking element is operated, thus unlocking the moving control element. 
     The following text explains features which can occur in conjunction with both embodiments, but are not absolutely essential. 
     The first control element comprises a first gate, and the second control element a second gate. These gates can be moved with respect to one another. Each gate is firmly connected to a handle which can be operated by hand. The handle can be passed through the gate. A part of the handle may form an operating cam, which is coupled to an operating element of a switch. 
     The gates are geometrically designed such that they do not block one another when the control elements are in an operating position other than the manual operation position. By way of example, a gate is a thin plate or a metal sheet. 
     When the first gate is in the manual operation position, this prevents movement of the second gate to the position which corresponds to the manual operation position. When the second gate is in the manual operation position, this prevents movement of the first gate to the position which corresponds to the manual operation position. 
     The electrically operated blocking element is preferably arranged between the gates of the first and second function units. 
     The switchgear assembly preferably comprises a locking element which makes it possible to prevent inadvertent switching between the various operating positions. The locking element preferably comprises a tension spring and a control button. The locking element can be recessed. The locking element or the control button preferably has an area with a narrowed cross section, which is arranged between two areas with a broader cross section. 
     Each gate preferably has an opening which is in the form of a channel and whose width outside the areas which are intended to be used as a latching position is less than the cross-sectional size of the broad areas of the locking element. In areas which are intended to be used as a latching position, the opening which is in the form of a channel has a width which is greater than the cross-sectional size of the broad areas of the locking element. 
     Each control element preferably has an operating cam which is firmly connected to the gate of the respective function unit. The operating cam may have a depression into which an operating element of an electrical switch projects. In the movement direction, the profile of the depression is of such a size that the operating element is moved between the operating positions in the vertical direction when the control element is moved. The operating element of the electrical switch preferably has sprung characteristics. By way of example, it may be a bent or folded leaf spring. 
     The electrical switch is preferably electrically connected to a safety circuit for evaluation of the safety information. 
     In one exemplary embodiment, the gates can be moved in a longitudinal direction with respect to one another. The gates are preferably each guided by a rail along which they can slide. In this case, when the first gate is in the manual operation position, this gate prevents the movement of the second gate to the position which corresponds to the manual operation position. Conversely, when the second gate is in the manual operation position, this gate prevents the movement of the first gate to the position which corresponds to the manual operation position. 
     In one variant, the first control element comprises a first gate, which can be pivoted about a first rotation axis, and the second control element comprises a second gate, which can be pivoted about a second rotation axis. When the first gate is being pivoted, this results in a change in the operating position of the first control element. When the second gate is being pivoted, this results in a change in the operating position of the second control element. 
     The gates can preferably be pivoted with respect to one another. The gates which can be pivoted are also referred to as gate levers. 
     The first gate preferably has a projection which pivots into a recess in the second gate on selection of position A) of the first control element, thus blocking the selection of the manual operation position. The second gate, analogously to this, likewise has a projection which pivots into a recess in the first gate on selection of position A) of the second control element, thus blocking the selection of the manual operation position. 
     When the first gate is in the manual operation position, this gate prevents the second gate from pivoting into the position which corresponds to the manual operation position. Analogously to this, when the second gate is in the manual operation position, this gate prevents the first gate from pivoting into the position which corresponds to the manual operation position. 
     Each function unit comprises a hand crankshaft which can be operated manually when manual operation is allowed and which, when the control element of this function unit is in an operating position other than the manual operation position, is covered by the gate of this control element. In one advantageous variant, each gate has a recess which is positioned in the manual operation position such that the hand crankshaft is exposed. 
     Each control element may comprise a stopper which is firmly connected to the gate of this control element. The hand crankshaft preferably has projections which extend in radial directions, that is to say in a direction at right angles to the rotation axis of the crankshaft, and strike against the stopper in the blocking position during rotation of the hand crankshaft. 
     The handle may have an area with a narrowed cross section, which is arranged between two areas with a broader cross section. In conjunction with this, the switchgear assembly preferably has a cover plate which has a first opening in the area of the first crankshaft, and a second opening in the area of the second crankshaft. For each function unit, the cover plate has an opening which is in the form of a channel and whose width outside the areas which are intended to be used as a latching position is less than the cross-sectional size of the broader areas of the handle. In areas which are intended to be used as a latching position, the opening which is in the form of a channel has a width which is at least as large as the cross-sectional size of the broader areas of the handle. 
     In a further embodiment, after the lock has been unlocked, the control element can be moved back to the neutral position B) or E) by a return element, for example in the form of an M-shaped return spring. 
     The handle is preferably coupled to an operating element of an electrical switch which is electrically connected to the circuit for evaluation of the safety information. The circuit for evaluation of the safety information is preferably electrically connected to a solenoid, which pulls in the blocking element when manual operation is allowed by the circuit for evaluation of the safety information. 
     A free space is provided between the gates in position B), which free space is covered by movement of one of the gates to position A) to such an extent that movement of the other gate to position A) is blocked. 
     The manual operation interlock can in principle be provided by means of linearly movable control elements which, for example, comprise slide gates, or by means of control elements which can pivot and, for example, comprise levers, and in particular gate levers. The manual operation interlock is designed such that it results in unambiguous control guidance, taking account of the locking and safety conditions, via the control elements and solenoids. Only a single solenoid is required for this purpose, since this is ensured by appropriate interlocking. Furthermore, separate blocking of the individual functions (isolator/grounder) is possible since one hand crank hole is in each case provided for each function unit both in the gate and in the cover plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Furthermore, exemplary embodiments will be explained with reference to schematic figures, which are not to scale, in which: 
         FIG. 1A  shows the plan view of a switching device with gate levers which can pivot; 
         FIG. 1B  shows the front view of the switching device shown in  FIG. 1A  in the neutral position; 
         FIG. 2A  shows the plan view of a switching device with linearly movable gates; 
         FIG. 2B  shows the front view of the switching device shown in  FIG. 2A , in the neutral position; 
         FIG. 3  shows the front view of the switching device shown in  FIG. 2A  during movement from the neutral position into the manual operation position when manual operation has not yet been allowed; 
         FIG. 4  shows the front view of the switching device shown in  FIG. 2A , in the manual operation position with manual operation allowed; and 
         FIG. 5  shows the front view of the switching device shown in  FIG. 2A  in the blocking position. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1A ,  1 B show an exemplary embodiment of a switchgear assembly with control elements which can pivot. The switchgear assembly comprises two function units: an isolator  401  (on the left) and a grounder  402  (on the right). These function units are preferably symmetrical with respect to an axis of symmetry which runs through the center point of the assembly. 
     The manual operation interlock comprises two hand crankshafts  1  (for the isolator) and  2  (for the grounder). These crankshafts are associated with two gate levers  3 ,  4 . The gate lever  3  is mounted at the rotation point  5 , and the gate lever  4  at the rotation point  6 . An operating cam  7 ,  8  is fitted to each gate lever and acts on the operating element of a switching element  9 ,  10  during rotation. 
     The switching elements  9 ,  10  are used for electrical locking and deactivation. Each switching element is electrically connected to a downstream control and protection circuit and is suitable for checking safety information. The operating cams  7 ,  8  are designed to be matched to the requirements for control and protection. 
     A locking magnet  11  with an electrically operated blocking element  12  (locking pin) is located between the gate levers  3 ,  4 . The gate levers are equipped with a removable locking element  13 ,  14  which has an opening  15 ,  16  for hooking a padlock into. The locking element  13 ,  14  is preferably a blocking bolt. The gate lever  3 ,  4  is firmly connected to an operating handle  17 ,  18 , which can be latched in three positions A, B, C. Switching between the positions A, B, C is carried out manually with the aid of the handle  17 ,  18 . 
     The latching position A represents manual crank operation/emergency operation. The latching position B represents the neutral position, in which the switchgear assembly is operated electrically (normal operation). The latching position C is the blocked position, in which the switchgear assembly is blocked such that it cannot be switched either electrically or mechanically. 
     The gate levers  3 ,  4  are designed and are positioned relative to one another such that these three latching positions are possible. 
     The switchgear assembly comprises a cover plate  200 , which has an opening  201 ,  202  for each function unit. This opening is in the form of a channel and is designed with broadened areas at those points which define the latching positions A, B and C of the control element. The cover plate  200  has a hand crank hole  19 ,  20  for each function unit. 
     The gate lever  3 ,  4  has a first recess  205 ,  206  with a touching area  21 ,  22 . When the respective control element is moved to position A, the touching area  21 ,  22  is moved in the direction of the blocking element  12 . When manual operation is not allowed, the touching area  21 ,  22  is blocked by the blocking element  12 , before the handle  17 ,  18  reaches the latching position A. The gate lever  3 ,  4  also has a locking projection  23 ,  24 . The gate lever  3 ,  4  has a second recess  303 ,  304  which at least partially covers the hand crank hole  19 ,  20  in the latching positions B, C. 
     A hole through which the blocking bolt  13  is passed is provided in the gate lever  3 ,  4 . Three openings, through which the blocking bolt  13  can be passed in the latching positions A, B, C, are preferably provided in the cover plate  200 . However, this may also be a single opening. 
     The method of operation of a function unit of the switching device for the isolator will now be explained. However, the description also applies, without any restriction, to the grounder. 
     In the neutral position B, the hand crank holes  19 ,  20  are covered by a part of the gate lever  3 ,  4 . If manual operation to position A (for example in the case of the isolator) is intended, the blocking bolt  13  is first of all removed. After this, the operating handle  17  is pulled out of the latching position B or C, and is moved in the direction of the latching position A. 
     Before the touching area  21  of the gate lever  3  reaches a position at which the locking pin  12  is arranged, the switching element  9  is operated via the operating cam  7 , thus initiating the process of checking whether manual operation is allowed. If manual operation is allowed, the locking magnet  11  pulls in the locking pin  12 , as a result of which the gate lever  3  is unlocked and can be moved to the latching position A. 
     In order to prevent the possibility of the gate lever  4  of the right-hand function unit now also being moved to the latching position A when the blocking element  12  is pulled in, the locking projection  23  of the gate lever  3  is pivoted into the first recess  206  in the gate lever  4 . In this case, the gate lever  4  is blocked by the locking projection  23  against movement to the latching position A. When one gate is in the latching position A, this therefore locks the gate of the other function unit such that it cannot assume the latching position A. 
     The operating handle  17  latches in in the latching position A. This means that the second recess  303  in the gate lever  3  completely exposes the hand crank hole  19 . This allows access to the hand crankshaft  1 . The hand crankshaft  1  preferably has at least one latching element, such that it is possible to engage a hand crank for operation of the crankshaft (lock-and-key principle). The hand crank is passed through the opening  19  in the cover plate  200  and the second recess  303  in the gate lever  3 . In the variant shown in  FIGS. 1A ,  1 B, the latching element is in the form of a radial projection. The hand crank has a depression which is designed to be complementary to this. Conversely, it is also possible for the crankshaft to be formed with a depression, and the hand crank with a complementary projection. 
     In the latching position A, the left-hand function unit is electrically blocked by the switching element  9 , which is operated by the operating cam  7 . Depending on the design of the control and protection circuit, the right-hand function unit can likewise be electrically blocked against operation in this position. 
     If it is found that manual operation is not allowed on checking via the cam  7 , the locking pin  12  remains in the extended state, as a result of which the gate lever  3  can be blocked, and cannot be moved to the latching position A. The hand crank hole  19  is still covered by a part of the gate lever  3 , so that the user cannot access the hand crankshaft. 
     If the left-hand function unit is intended to be blocked, starting from the neutral position B, the gate lever  3  is moved to the latching position C. The blocking bolt  13  must be removed again before moving to the latching position C. After this, the operating handle  17  is pulled out of the latching position, and is moved in the direction of the position C. The operating handle  17  latches in on reaching the position C. The blocking bolt  13  is then inserted again. At the same time, the left-hand function unit is electrically locked via the operating cam  7 , and the hand crankshaft  1  is mechanically blocked with the aid of the stopper  25 . A lock can be hooked into the hole  15  in the blocking bolt  13 . 
     The locking magnet  11  is preferably not operated for blocking the function unit in the latching position C. This is important in order to ensure that the hand crank check still remains activated for the other function unit, so that the right-hand function unit—except for the latching position A—can be operated independently of the left-hand function unit. 
     The gate levers  3 ,  4  are designed such that the gate lever  4 —taking account of whether this is allowed by the control and protection circuit—can be moved even when the lever  3  is in the latching position C or B. Both sides of the drive can therefore be locked separately. However, manual crank operation is in each case only ever possible for one function unit, when this is allowed after checking the safety information. Electrical operation is ensured in the neutral position B. 
     The right-hand function unit comprises a stopper  26  and a blocking bolt  14  which has a hole  16 . The blocking bolt  14  is designed like the blocking bolt  13 . The hole  16  corresponds to the hole  15 . The stopper  26  corresponds to the stopper  25 . 
     According to further embodiments, which are explained in  FIGS. 2A to 5 , the manual operation interlock is designed with slides  103 ,  104  which can be moved linearly. The rotation points  5 ,  6 , which are shown in  FIGS. 1A ,  1 B, are in this case replaced by linear guides  105 ,  106 . A linear guide preferably comprises at least one rail. The elements which are comparable with the elements  1 ,  2  and  7  to  24  are also provided in this variant, and, for ease of comparison, are provided with numbers increased by 100. 
       FIGS. 2A ,  2 B show the neutral position E of the moving control elements of the two function units.  FIG. 3  shows the movement of the control element of the left-hand function unit from the position E to the position D, and  FIG. 4  shows the position D of this control element.  FIG. 5  shows the position F of this control element. 
     The slides have three latching positions D, E, F. The latching position D corresponds to the latching position A in the variant with gate levers which can pivot. The latching position E corresponds to the latching position B, and the latching position F to the latching position C. 
     The slides  103 ,  104  are designed and positioned relative to one another such that these three latching positions are possible. In this variant as well, each gate  103 ,  104  has a second recess  303 ,  304 , which is likewise intended to expose the hand crankshaft when manual operation is allowed. Each slide gate  103 ,  104  also has a third recess  203 ,  204  which is designed essentially in the same way as the openings  201 ,  202  in the cover plate  200  in the variant shown in  FIG. 1B . The third recess  203 ,  204  is in the form of a channel with broadened areas at the points which define the latching positions D, E and F of the control element. 
     The blocking bolt  113 ,  114  preferably comprises a control button which can be recessed and projects out of the cover plate  200  in the latching positions D, E, F. The blocking bolt  113 ,  114  furthermore comprises a tension spring. The blocking bolt  113 ,  114  in this variant is designed such that it can be recessed in a spring-loaded manner, that is to say it can be pushed in. Once the blocking bolt  113 ,  114  has been recessed, the slide  103 ,  104  can be operated. The blocking bolt  113  carries out the function of “latching” of the operating handle  17  in the variant shown in  FIGS. 1A and 1B . In contrast to the variant shown in  FIGS. 1A ,  1 B, the opening  201 ,  202  in the cover plate  200  is implemented in the form of a channel without any broadened areas in the latching positions. Otherwise, the conditions are the same. The features which have been described for the handle  17 ,  18  can be transferred without any restriction to the blocking bolt  113 ,  114 . In particular, like the handle  17 ,  18 , the blocking bolt  113 ,  114  has an area with a narrowed cross section. Like the blocking bolt  13 ,  14 , the blocking bolt  113 ,  114  has a hole  115 ,  116  for a padlock to be passed through. 
     The latching position D represents manual crank operation/emergency operation. The latching position E represents the neutral position, in which the switchgear assembly is electrically operated (normal operation). The latching position F is the blocked position, in which the switchgear assembly is blocked such that it cannot be switched either electrically or mechanically. 
     A free space  207  is provided between the slide gates  101 ,  102  in position E), which free space  207  is covered by movement of one of the slide gates to position D) to such an extent that movement of the other slide gate to position D) is blocked. 
     In the neutral position E, the hand crank holes  119 ,  120  in the cover plate  200  are covered by a part of the slide  103 ,  104 . If manual operation is now intended to the latching position D (for example for the left-hand function unit), the blocking bolt  113  is first of all pressed. The operating handle  117  is then moved in the direction of the latching position D. 
     Before the touching area  121  of the slide gate  103  reaches a position at which the locking pin  112  is arranged, the switching element  109  is operated via the operating cam  107 , thus initiating the check of whether manual operation is allowed. If manual operation is allowed, the locking magnet  111  pulls in the locking pin  112 , thus unlocking the slide gate  103  and allowing movement to the latching position D. 
     In order to prevent the slide gate  104  of the right-hand function unit now also being moved to the latching position D when the blocking element  112  is pulled in, the slide  104  is blocked—when the slide gate  103  is in the latching position D—by the locking area  123  of the slide  103  against movement to the latching position D. When a slide gate is in the latching position D, this thus locks the slide gate of the other function unit such that it cannot assume the latching position D. 
     The blocking bolt  113  latches in in the latching position D. This means that the second recess  303  in the slide gate  103  completely exposes the hand crank hole  119 . This allows access to the hand crankshaft  101 . 
     The left-hand function unit is electrically blocked in the latching position D by the switching element  109 , which is operated by the operating cam  107 . Depending on the design of the control and protection circuit, the right-hand function unit can likewise be electrically blocked against operation in this position. 
     If manual operation is not allowed on checking via the cam  107 , the locking pin  112  remains in the extended state, as a result of which the slide gate  103  is blocked and cannot be moved to the latching position D. The hand crank hole  119  is still covered at least by a part of the slide gate  103 , so that the user cannot access the hand crankshaft. 
     If the intention is to block the left-hand function unit starting from the neutral position E, the slide gate  103  is moved to the latching position F. The blocking bolt  13  is pressed before movement to the latching position F. The operating handle  117  is then moved in the direction of the latching position F. On reaching the position F, the blocking bolt  113  latches in. At the same time, the left-hand function unit is electrically locked via the operating cam  107 , and the hand crankshaft  101  is mechanically blocked with the aid of the stopper  125 . A lock can be hooked into the hole  115  in the blocking bolt  113 . 
     The locking magnet  111  is preferably not operated for blocking the function unit in the latching position F. This is important in order to ensure that the hand crank check still remains activated for the other function unit, such that the right-hand function unit can be operated in the latching positions E, F independently of the left-hand function unit. 
     The slide gates  103 ,  104  are designed such that the slide gate  104 —taking account of whether this is allowed by the control and protection circuit—can be moved even when the slide  103  is in the position F or E. 
     Both sides of the drive can thus be locked separately. However, hand crank operation is in each case only ever possible for one function unit, when this is allowed after checking the safety information. Electrical operation is ensured in the neutral position E. 
     The operating cam  117 ,  118  has a depression into which an operating element  301 ,  302  of an electrical switch  109 ,  110  projects. The profile of the depression in the movement direction is of such a size that the operating element  301 ,  302  is moved in the vertical direction when the control element is moved between the operating positions. The operating element of the electrical switch  109 ,  110  may, for example, be a leaf spring. 
     The specified switching device is not restricted to the above examples. The number and form of the elements shown can be chosen as required in order to provide the described method of operation of the function unit. 
     For example, the blocking bolts  113 ,  114  can be designed such that they must be pulled against a spring element in order to lock the gate  103 ,  104  in the position D, E, F. In the pulled state, the blocking bolt  113 ,  114  can be locked, for example by a padlock, via the hole  115 ,  116 . When the padlock is removed, the spring element pulls the blocking bolt back and releases the gates  103 ,  104 . If this was previously in the position D) or F), it is moved back via a return spring  130 ,  131 , for example M-shaped leaf spring, to the neutral position D), and is held there. There is then no need for latching. All the other described characteristics remain unchanged in this case. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  First crankshaft 
           2  Second crankshaft 
           3  First gate lever 
           4  Second gate lever 
           5  First rotation axis 
           6  Second rotation axis 
           7 ,  8  Operating cam 
           9 ,  10  Switch 
           11  Solenoid 
           12  Electrically operated blocking element 
           13 ,  14  Locking element 
           15 ,  16  Hole in the locking element 
           17 ,  18  Handle 
           19 ,  20  Opening in the cover plate  200   
           21  Touching area of the first gate lever  3   
           22  Touching area of the second gate lever  4   
           23  Locking projection of the first gate lever  3   
           24  Locking projection of the second gate lever  4   
           25 ,  26  Stopper 
           101  First crankshaft 
           102  Second crankshaft 
           103  First gate 
           104  Second gate 
           105  Rail for guiding the first gate 
           106  Rail for guiding the second gate 
           107 ,  108  Operating cam 
           109 ,  110  Switch 
           111  Solenoid 
           112  Electrically operated blocking element 
           113 ,  114  Locking element 
           115 ,  116  Hole in the locking element 
           117 ,  118  Handle 
           119 ,  120  Opening in the cover plate  200   
           121  Touching area of the first gate  103   
           122  Touching area of the second gate  104   
           123  Locking area of the first gate  103   
           124  Locking area of the second gate  104   
           125 ,  126  Stopper 
           130 ,  131  Return spring 
           200  Cover plate 
           201 ,  202  Opening in the cover plate  200   
           203 ,  204  Third recess in the gates 
           205 ,  206  First recesses in the gates 
           207  Free space 
           301  Operating element of the electrical switch  109   
           302  Operating element of the electrical switch  110   
           303 ,  304  Second recess in the gates 
           401  First function unit of the switching device 
           402  Second function unit of the switching device