Abstract:
In an exemplary embodiment of the present invention, a locking arrangement for use on a draw-out mechanism mounted on a circuit breaker within a switchgear cabinet includes a fixed side plate arranged for mounting within switchgear cabinet, a mobile side plate includes a pin extending therefrom, the mobile side plate arranged to move the circuit breaker in cooperation therewith and an obstructor plate pivotally mounted to the fixed sideplate, the obstructor plate having a slot and a notch extending from the slot, the pin traversing the slot to allow the mobile side plate to move relative to the fixed side plate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application No. (N.Y.A.—Attorney Docket No. 75FR-100) filed on Dec. 7, 2000, pending.  
         [0002]    This application is based upon, and claims the benefit of, U.S. Provisional Patent Application Ser. No. 60/190,643 filed on Mar. 20, 2000, which is herein incorporated by reference and application Ser. No. 0003485 filed on Mar. 17, 2000, in France, which is herein incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to a draw-out unit for electrical switchgear cabinets. More specifically, this invention relates to a locking arrangement for a circuit breaker draw-out unit.  
           [0004]    The use of switchgears in electrical distribution systems is well known. The switchgear houses a plurality of draw-out units, with each draw-out unit housing one or more switching devices, such as motor controllers and circuit breakers, releasably interconnected to one or more busbars. Periodically, the draw-out units are removed from the switchgear to allow for maintenance of equipment. The switching devices within the draw-out units make electrical contact with the busbars through a plurality of clip connectors, which extend from the draw-out unit. Each clip connector is electrically connected to an electrical conductor for connection to the switching devices of the switchgear. As the draw-out unit is inserted into the switchgear, the busbar slides between the two contact arms, and the contact arms frictionally engage the busbar.  
           [0005]    Draw-out mechanisms are known in the art for use with molded case circuit breakers. One such mechanism is described in U.S. Pat. No. 4,743,715 issued May 10, 1988. These mechanisms have discrete positions for testing, installing and removing the circuit breaker. The positions are CONNECT, DISCONNECT and TEST. In the CONNECT position the circuit breaker can be closed, opened or tripped. In the DISCONNECT position the circuit breaker is in the trip position. The third position is TEST, wherein the circuit breaker is disconnected from the main circuit. In the TEST position the circuit breaker can be closed, opened or tripped in order to check internal and external accessories such as auxiliary switches, shunt trip and under voltage and secondary circuits.  
           [0006]    It is frequently necessary to ensure that electrical equipment cannot be operated, for example while maintenance work is being carried out. It is essential to ensure that circuit breakers in a draw out mechanism are secured in the DISCONNECT position to avoid inadvertent operation that can lead to unplanned personnel exposure or equipment damage  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    In an exemplary embodiment of the present invention, a locking arrangement for use on a draw-out mechanism mounted on a circuit breaker within a switchgear cabinet includes a fixed side plate arranged for mounting within switchgear cabinet, a mobile side plate includes a pin extending therefrom, the mobile side plate arranged to move the circuit breaker in cooperation therewith and an obstructor plate pivotally mounted to the fixed sideplate, the obstructor plate having a slot and a notch extending from the slot, the pin traversing the slot to allow the mobile side plate to move relative to the fixed side plate.  
           [0008]    The above discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The present invention will now be described, by way of example, with reference to the following FIGURES, in which:  
         [0010]    [0010]FIG. 1 is a partially exploded perspective view of the draw-out mechanism of the present invention;  
         [0011]    [0011]FIG. 2 is a side view of the draw-out mechanism of FIG. 1 in the CONNECT position;  
         [0012]    [0012]FIG. 3 is side view of the draw-out mechanism of FIG. 1 in the DISCONNECT position;  
         [0013]    [0013]FIG. 4 is a side view of the draw-out mechanism of FIG. 1 in the TEST position;  
         [0014]    [0014]FIG. 5 is a side view of the cam of the draw-out mechanism of FIG. 1;  
         [0015]    [0015]FIG. 6 is a side view of the indicator of the draw-out mechanism of FIG. 1;  
         [0016]    [0016]FIG. 7 is a side view of a mobile side plate of the draw-out mechanism of FIG. 1;  
         [0017]    [0017]FIG. 8 is a side view of one of a pair of fixed side plates of the draw-out mechanism of FIG. 1;  
         [0018]    [0018]FIG. 9 is a side view of the obstructor plate of the draw-out mechanism of FIG. 1;  
         [0019]    [0019]FIG. 10 is a side view of the locking slide of the draw-out mechanism of FIG. 1;  
         [0020]    [0020]FIG. 11 is a perspective view of an alternative embodiment of a locking arrangement for the draw out mechanism;  
         [0021]    [0021]FIG. 12 is a perspective view of the locking arrangement of FIG. 11;  
         [0022]    [0022]FIG. 13 is the locking arrangement of FIG. 11 in the locked position;  
         [0023]    [0023]FIG. 14 is a perspective view of a second alternative embodiment of a locking arrangement for the draw out mechanism; and  
         [0024]    [0024]FIG. 15 is a partial enlarged perspective view of the obstructor plate showing a spring. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    Referring now to FIG. 1, the draw-out mechanism (unit) of the present invention is shown generally at  100 . The draw-out mechanism  100  is generally comprised of a pair of fixed side plates  400  disposed parallel to one another. Interior to the pair of fixed side plates  400  are disposed a mobile side plate  310  and mobile side plate  318 . The mobile side plate  318  comprises essentially a flat plate while the mobile side plate  310  comprises a bent plate in an essentially step like form including a front piece  320  whereby the mobile side plate  310  and the mobile side plate  318  are juxtaposed in proximity to one another. Continuing in FIG. 1, the draw-out mechanism  100  further comprises a plug-in base  700  disposed between the mobile side plate  310  and the mobile side plate  318 . The plug-in base  700 , the mobile side plate  310 , the mobile plate  318  and the front piece  320  define an interior chamber  702  operative to accept therein a circuit breaker such as a molded case circuit breaker (MCCB, not shown). The circuit breaker (not shown) is secured to mobile side plate  318 , allowing the circuit breaker to move with mobile side plate  318  in a manner described hereinafter. A cam  302  is juxtaposed between the plug-in base  700  and the mobile side plate  310 . A locking slide  602  is disposed between the mobile side plate  318  and one of the fixed side plates  400 . Further in FIG. 1, a screw  202  is made accessible to a crank  200  whereby the draw-out mechanism  100  may be brought to one of a plurality of positions. The draw-out mechanism  100  is connected to an electrical distribution circuit (not shown) at the clip connectors  704 . An electrical socket (not shown) is fixed to base  700  within interior chamber  702  and forms a releasable connection with a plug (not shown) extending from the circuit breaker to connect the circuit breaker with the main circuit via clip connectors  704 .  
         [0026]    The aforesaid positions of the draw-out mechanism  100  are firstly that of CONNECT, wherein the circuit breaker is connected to the main electrical circuit (not shown). In the CONNECT position the circuit breaker can be closed, open or tripped. The second position is DISCONNECT, wherein the circuit breaker is disconnected (unplugged) from the main circuit. In the DISCONNECT position the circuit breaker is in the trip position and the draw-out mechanism  100  can be locked to prevent movement of the draw-out mechanism  100 . The third position is TEST, wherein the circuit breaker remains disconnected (unplugged) from the main circuit. In the TEST position the circuit breaker can be closed, open or tripped in order to check internal and external accessories such as auxiliary switches, shunt trip and under voltage and secondary circuits (not shown).  
         [0027]    Reference will now be had to FIGS. 2, 3 and  4  of the drawing to explain the mechanical configurations assumed by the draw-out mechanism  100 . In the interest of clarity, reference is also made to FIGS. 5 through 10 of the drawing. In FIG. 2, the draw-out mechanism  100  is in the CONNECT position which is indicated on the first position indicator  506  of the indicator  500  and can be viewed through the indicator port  512 . A crank  200  is inserted through a crank port  208  in the command box  800  and into a socket  209  formed in a sleeve  210 . Sleeve  210  is secured to a screw  202  thereby allowing crank  200  to turn the screw  202 . The crank  200  and screw  202  in combination extend essentially the full depth of the draw-out mechanism  100  from front to back. At the back end of the screw  202  a threaded collar  206  is threadably engaged to the screw  202 . The collar  206  includes a pin  204  affixed thereto and disposed within a slot  304  in a cam  302  of a cam system  300 . The crank  200 , screw  202 , collar  206  and cam  302  in combination operate such that as the crank  200  rotates, the collar  206  translates along the screw  202 . The movement of the pin  204  disposed in the slot  304 , rotates the cam  302  counterclockwise as viewed about an axis of rotation  308  affixed to the fixed side plate  400 . A pin  312  is affixed to the mobile side plate  310  and disposed within a slot  306  of the cam  302 . As the cam  302  rotates about the axis of rotation  308 , due to the action of the pin  204  and collar  206 , the pin  312  moves within slot  306  causing mobile side plate  310  to move toward the front of the draw-out unit  100 .  
         [0028]    Continuing in FIG. 2, the mobile side plate  310  has a pin  314  affixed thereto. The indicator  500  is affixed to the fixed side plate  400  at an axis of rotation  502  and free to rotate thereabout. The indicator  500  further comprises a slot  504 , which partly coincides with or overlaps a slot  402  in the fixed side plate  400 . The aforesaid pin  314  is disposed in the slot  402  in the fixed side plate  400  and in the slot  504  in the indicator  500 . Thus as the mobile side plate  310  moves, so moves the pin  314  along both the slot  402  and the slot  504 . This motion causes the indicator  500  to rotate about the axis of rotation  502 . Thus, from the CONNECT position, the rotation of the crank  200  and the screw  202  rotates the cam  302  about the axis of rotation  308  moving the mobile side plates  310 ,  318  from the back of the draw-out mechanism  100  toward the front thereof, and rotating the indicator  500  counterclockwise about the axis of rotation  502 . The circuit breaker, which is attached to mobile side plate  318 , also moves toward the front of draw-out unit  100 , unplugging the circuit breaker from the main circuit. Thus, the draw-out mechanism  100  assumes the DISCONNECT  508  position of FIG. 3.  
         [0029]    Continuing in FIG. 2, the draw-out mechanism  100  is further comprised of a locking device (arrangement)  600 . The locking system  600  includes a locking slide  602  and an obstructor plate  608 . In a first embodiment of the locking slide  602 , locking slide  602  includes a locking hole  604  and a pin  606  affixed thereto. The obstructor plate  608  includes an axis of rotation  610  about which the obstructor plate  608  is free to rotate. The axis of rotation  610  is affixed to the fixed side plate  400 . The obstructor plate  608  further includes a slot  614  and a slot  612  having a notch  616 . The locking system  600  is operative such that as the mobile side plate  310  moves from back to front due to the action of the crank  200  and screw  202 , a pin  316  attached to the mobile side plate  310  and disposed within the slot  612  and a slot  404  in the fixed side plate  400 , moves therewith within the slots  612 ,  404 . When the draw-out mechanism  100  has assumed the DISCONNECT position, the pin  316  is aligned with the notch  616 . The crank  200  is removed from the draw-out mechanism  100  and the locking slide  602  may be manually pulled in a direction away from the draw-out mechanism  100 . As such, the pin  606 , disposed within an slot  406  in the fixed side plate  400 , so moves and, engaged also with the slot  614 , causes the obstructor plate  608  to rotate clockwise as viewed about the axis of rotation  610  until the pin  316  is captured by the notch  616 . This action essentially aligns the obstructor plate  608  along with the screw  202  and a flange  609  extending from the obstructor plate  608  covers the socket  209  to prevent the crank  200  from being reinserted into the draw-out mechanism  100  in the DISCONNECT position shown in FIG. 3. The locking hole  604  is clear of the command box  800  and a lock (not shown) may be placed therein to prevent the draw-out unit  100  from being placed in the TEST or DISCONNECT positions. Because pin  316  is captured in notch  616 , mobile side plate  310  is fixed in the DISCONNECT position to further insure that the draw-out unit  100  is not placed in the TEST or DISCONNECT positions. In alternative embodiments, the obstructor plate  608  extends from draw-out mechanism  100  and is pivoted about axis  610  by hand. As such, locking slide  602  is not necessary. Additionally, obstructor plate  608  may be biased in a counter-clockwise direction about axis  610  using, for example, a spring extending from the fixed side plate  400  to the obstructor plate  608 . Biasing the obstructor plate  608  would pivot the obstructor plate  608  such that notch  616  captures pin  316  as soon as crank  200  is removed, provided that the draw-out mechanism  100  is in the DISCONNECT position.  
         [0030]    Continuing in FIG. 3, in order for the draw-out mechanism  100  to proceed from the DISCONNECT position to the TEST position, the aforesaid lock is removed from the locking hole  604  and the locking slide  602  is manually pushed into the draw-out mechanism  100 . Such action rotates the obstructor plate  608  counterclockwise as viewed, thereby disengaging the pin  316  from the notch  616  and allowing the crank  200  to be reinserted into the draw-out mechanism  100  to engage the socket  209 . Upon further rotation of the crank  200 , the screw  202  and the pin  204  continue to move to the front of the draw-out mechanism  100  and continue to rotate the cam  302  counterclockwise as viewed. As such, the slot  306  drives the pin  312 , the mobile side plates  310  and  318 , and the circuit breaker towards the front of the draw-out mechanism  100 . In addition, pin  314  continues to move along the slot  402  and the slot  504 . This in turn continues to rotate the indicator  500  counterclockwise as viewed about the axis of rotation  502  until the indicator  500  comes to rest in the TEST position of FIG. 4 viewable through the indicator port  512 . The draw-out mechanism  100  may be returned to the DISCONNECT or CONNECT positions from the TEST position by reversing the aforesaid action of the crank  200  and the screw  202 .  
         [0031]    Cam  302 , indicator  500 , mobile and fixed side plates  310 ,  400  and obstructor plate  608  are substantially flat structures that can be arranged in close proximity to each other creating a compact draw-out mechanism  100 . Thus, the draw-out mechanism  100  provides a compact arrangement allowing the associated circuit breaker to be placed in CONNECT, DISCONNECT and TEST positions. Because the draw-out mechanism  100  is compact, it can be used with smaller sized circuit breakers. In addition, the draw-out mechanism  100  provides position indicator and locking features within the compact arrangement. For clarity, FIGS. 5 through 10 are views of the various components of the draw-out mechanism  100  shown in FIGS. 1 through 4.  
         [0032]    Referring to FIGS. 11 and 12, an alternative locking arrangement (device) for the draw out mechanism  100  (FIG. 1) is shown at  900 . Like reference numerals refer to like parts of FIGS. 1 through 10. The components of the locking device  900  are mounted on the fixed side plate  400 . The draw out mechanism consists of lead screw  202  and collar  206 , which when rotated by means of crank  200  gives linear motion to the collar (rider)  206 . The crank  200  extends from an opening  1002  located in surface  1000  of front piece  320 . The opening  1002  is aligned with crank port  208  located on the front cover  928 . The mobile side plate  310  is operatively engaged to the collar  206  and guided in the fixed side plate  400  such that the mobile side plate  310  moves linearly with the collar  206 .  
         [0033]    The obstructor plate  902  includes a slot (main slot)  904  and having a notch, preferably a circular slot,  960  extending out from the main slot  904 . Circular slot  960  is in open communication with main slot  904  as shown in FIG. 11. This mobile side plate  310  is provided with two pins,  314  and  316 . Pin  314  is used to rotate the position indicator  500  through the cam shaped slot  504  provided in the position indicator  500 . The display of the position indicator  500  is seen through the indicator port  512  (FIG. 2) provided on a front cover  928  of the draw-out mechanism. The second pin  316  is engaged in the main slot  904  provided on a lock link (obstructor plate)  902 , which is fixed to the fixed side plate  400  and is free to rotate about a rivet pin  910 . The obstructor plate  902  is loaded with a spring  1202 , preferably a torsion spring, the placement of which on the obstructor plate  902  is shown in FIG. 15. Spring  1202  provides rotating torque to the obstructor plate  902  in the counter-clockwise direction about rivet pin  910 . The obstructor plate  902  has an outer surface  938  facing the fixed side plate  400  and an opposing inner surface  936  facing the interior of the draw-out mechanism  100  (FIG. 1). Spring  1202  is connected at one end to the obstructor plate  902  and at an opposing end to fixed side plate  400 .  
         [0034]    A blocking link (block link)  912  includes a main body portion  932  having an end  950  and an opposing end  952 . A flange  930  extends from end  952 . Blocking link  912  is riveted on the fixed side plate  400  and is free to rotate about the rivet pin  914 . A projection (pin)  934  on the outer surface  938  of the obstructor plate  902  engages in a slot  916  provided on the main body portion  932  of the blocking link  912 . Thus, the rotary motion (counter-clockwise) of obstructor plate  902  about rivet pin  910  is transferred to blocking link  912  such that the blocking link  912  rotates (clockwise) about rivet pin  914 .  
         [0035]    The locking slide (lock plate)  602  includes a first end  940  and a second end  942 . The first end  940  of the locking slide  602  is provided with locking hole  604  for insertion of padlocks  922  and the second end  942  of the locking slide  602  includes a slot  920 . A projection (pin)  918  on the inner surface  936  of the obstructor plate  902  engages slot  920  of the locking slide  602 , as shown in FIG. 12. The rotation of the obstructor plate  902  gives linear motion to locking slide  602 . Thus, the locking slide  602  is guided through a slot  1004  located on the front piece  320  and through a slot  1006  provided on the front cover  928 . Slot  1004  and slot  1006  are aligned with each other. Further, slots  924  are also provided on locking slide  602  to engage tabs  948  extending from figure locks  926 . It is noted that when the locking slide  602  projects out from the front cover  928 , this provides an indication on the front cover  928  that the circuit breaker has reached the DISCONNECT position.  
         [0036]    When the circuit breaker (not shown) is moved from the CONNECT (plug in) position to the DISCONNECT (isolated) position as shown in FIG. 12, it cannot be locked unless it fully reaches the DISCONNECT position because obstructor plate  902  is prevented from rotating by pin  316 . Pin  316  cannot move into the circular slot  960 .  
         [0037]    When the circuit breaker has reached the DISCONNECT position, the obstructor plate  902  rotates under the bias of the spring  1202  (FIG. 15) such that pin  316  is fully engaged within the circular slot  960  of main slot  904 , as shown in FIG. 12. The rotation of the obstructor plate  902  moves the locking slide  602  linearly and projects the locking hole  604  out through slot  1004  located on the surface  1000  of front piece  320  in order that a lock, preferably a padlock  922  can be fastened thereto. This action also provides an indication on the front cover  928  that the circuit breaker has reached the DISCONNECT position. Further, the rotation of the blocking link  912  causes the flange  930  to block access to the crank port  208 .  
         [0038]    To lock the circuit breaker, the crank  200  is removed from crank port  208 . Removal of crank  200  from crank port  208  when the circuit breaker is fully in the DISCONNECT position frees the blocking link  912  and the obstructor plate  902  to rotate. The flange  930  of the blocking link  912  blocks access to the crank port  208 . The locking slide  602  projects out of the front cover  928 . The padlocks  922  can be inserted and the figure locks  926  can be operated with a key so that tabs  948  on the figure locks  926  engage the slots  924  in locking slide  602 , thereby locking the circuit breaker in the DISCONNECT position and preventing tampering of the draw out mechanism  100  and the locking device  900 .  
         [0039]    Thus, locking arrangement  900  provides that once the crank  200  is withdrawn as shown in FIG. 12, permits the locking arrangement  900  to be locked and access to opening  1002  is blocked thereby preventing the crank  200  to operate the draw out mechanism  100  (FIG. 1). Further, the locking of the locking arrangement  900  can employ padlocks  922  or figure locks  926  or both as desired by the end user.  
         [0040]    Referring to FIGS. 13 and 14, a second alternative embodiment is shown for the locking arrangement  900  where like reference numerals refer to like parts of FIGS. 1 through 12. Specifically, the features of the obstructor plate  902  and the blocking link  912  will be discussed in detail as it pertains to the second alternative embodiment for the locking arrangement  900 .  
         [0041]    In the second alternative embodiment, the blocking link  912  includes a main body portion  932  having an end  950  and an opposing end  952 . A flange  930  extends from end  952 . A spring, preferably an extension spring,  1100 , is also shown. Spring  1100  includes a movable end  970  and a fixed end  972 . The movable end  970  is attached to the end  950  of the blocking link  912  and the fixed end  972  is attached to a fixed pin  954  on the fixed side plate  400 . Spring  1100  provides bias to the blocking link  912  in a first direction when the crank  200  is inserted within opening  1002  of the front cover  928 .  
         [0042]    It is noted that the blocking link  912  does not employ slot  916  as shown in the first alternative embodiment of FIGS. 11 and 12. Further, obstructor plate  902  does not employ pin  934  as shown in the first alternative embodiment of FIGS. 11 and 12.  
         [0043]    In the second alternative embodiment, a projection  1300 , preferably a pin riveted on the outer surface  938  of the obstructor plate  902 , butts against a side  1200  of the main body portion  932  of the blocking link  912 . A clockwise rotary motion of the obstructor plate  902  is transferred via projection  1300  to rotate the blocking link  912  in a counterclockwise direction. Thus, the rotation of the obstructor plate  902  is transferred to the blocking link  912 .  
         [0044]    The obstructor plate  902  includes a main slot  904  and, unlike the first alternative embodiment, also includes an extended portion (extended slot)  1304 . Main slot  904  also includes a notch, preferably a circular slot,  960  extending out from the main slot  904  proximate to the extended portion  1304 . Circular slot  960  and extended portion  1304  of main slot  904  are in open communication with main slot  904  as shown in FIG. 13.  
         [0045]    The locking slide (lock plate),  602  is similar to that described hereinabove with reference to the first alternative embodiment. The locking slide (lock plate)  602  includes a first end  940  and a second end  942 . The first end  940  of the locking slide  602  is provided with locking hole  604  for insertion of padlocks  922  and the second end  942  of the locking slide  602  includes a slot  920 . A projection (pin)  918  on the inner surface  936  of the obstructor plate  902  engages slot  920  of the locking slide  602 , as shown in FIG. 12. The rotation of the obstructor plate  902  gives linear motion to locking slide  602 . Thus, the locking slide  602  is guided through a slot  1004  located on the front piece  320  and through a slot  1006  provided on the front cover  928 . Slot  1004  and slot  1006  are aligned with each other. Further, slots  924  are also provided on locking slide  602  to engage tabs  948  extending from figure locks  926 . It is noted that when the locking slide  602  projects out from the front cover  928 , this provides an indication on the front cover  928  that the circuit breaker has reached the DISCONNECT position.  
         [0046]    When the circuit breaker (not shown) is moved from the CONNECT (plug in) position to the DISCONNECT (isolated) position as shown in FIG. 12, it cannot be locked unless it fully reaches the DISCONNECT position because the obstructor plate  902  is prevented from rotating by pin  316 . Pin  316  cannot move into the circular slot  960 .  
         [0047]    When the circuit breaker has reached the DISCONNECT position, the obstructor plate  902  rotates under the bias of spring  1202  (FIG. 15) such that pin  316  is fully engaged within the circular slot  960  of main slot  904 , as shown in FIG. 12. It is noted that the spring  1202 , as shown in FIG. 15, is employed in both the first and second alternative embodiments. The rotation of the obstructor plate  902  moves the locking slide  602  linearly and projects the locking hole  604  out through slot  1004  located on the surface  1000  of front piece  320  in order that a lock, preferably a padlock  922  can be fastened thereto. This action also provides an indication on the front cover  928  that the circuit breaker has reached the DISCONNECT position.  
         [0048]    In the DISCONNECT position and unlike the first alternative embodiment, the blocking link  912  remains butted to the crank  200  due to the projection  1300  on the obstructor plate  902  that is pressing against the main body portion  932  of the blocking link  912 . In this condition, the crank  200  can not be rotated as the pin  316  is now in the circular slot  960  of the main slot  904  and therefore pin  316  can not move linearly. However, since the locking hole  604  of the locking slide  602  is projected out through the front cover  928 , the draw out mechanism  100  may be locked in the DISCONNECT position using the padlocks  922  with the crank  200  engaged in the crank port  208 .  
         [0049]    It is also noted that the crank  200  can be removed from crank port  208 . When the crank  200  is withdrawn from crank port  208 , the blocking link  912  under the urgence of the bias from spring  1100 , rotates clockwise thereby blocking access to crank port  208 .  
         [0050]    It is noted that the padlocks  922  can be inserted into locking hole  604  and the figure locks  926  can be operated with a key so that the tabs  948  on the figure locks  926  engage the slots  924  in the locking slide  602 , thereby locking the circuit breaker in the DISCONNECT position and preventing tampering of the draw out mechanism  100  and the locking device  900 .  
         [0051]    Thus, depending on whether the crank  200  is removed from the crank port  208 , the circuit breaker can be locked in the DSICONNECT position by any or all of the padlocks  922  and, additionally or alternatively, by any or all of the figure locks  926 . If the circuit breaker is to be moved from the DISCONNECT position, it is necessary to remove all padlocks  922  and unlock all figure locks  926  that were selectively employed with the locking device  900 . Once this is done, the locking slide  602  can be pressed back inside the front cover  928  which, in turn, rotates the blocking link  912  counter-clockwise. The counter clockwise rotation of the blocking link  912  in turn provides access to opening  1002  for insertion of crank  200 . When the locking slide  602  is pressed inside the front cover  924 , the pin  316  engages the main slot  904  from the end of the circular slot  960  such that the locking slide  602  is free to move to the extended slot  1304  or the main slot  904 . Then, the crank  200  can be inserted into crank port  208  to engage with collar  206 . Thus, the draw out mechanism  100  can be moved to the CONNECT or TEST positions. For motion towards the CONNECT position, pin  316  will travel in the main slot  904  while for motion towards the TEST position, pin  316  will engage the extended portion  1304 . This is accomplished as follows. To go from the DISCONNECT to the CONNECT position, the locking slide  602  is pressed against the front cover  928 . The crank  200  is inserted into the crank port  208  and then rotated keeping the locking slide  602  pressed against the front cover  928  till the crank  200  completes one rotation. This motion guides the pin  316  into the main slot  904 . Then, the end user may release the pressure applied to the locking slide  602  and rotate the crank  200  clockwise in order that the pin  316  will reach the CONNECT position. To go from the DISCONNECT to the TEST position, the same procedure above is followed except that once pin  316  is guided into the main slot  904 , the crank  200  is rotated counterclockwise in order that the pin  316  will reach the TEST position.  
         [0052]    While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.