Abstract:
Disclosed herein is a method of moving and altering movement of a breaker mounted spring discharge interlock lever during racking and unracking of a breaker with an enclosure. The method includes, rotating a racking screw to rack the breaker into or out of the enclosure, rotating a shaft in operable communication with the racking screw, translationally moving a cam with a link having one end disconnectably connected to the cam and an opposing end disconnectably connected to a crank, that is fixedly attached to the shaft, translationally moving a cam follower that is in operable communication with the cam, moving the breaker mounted spring discharge interlock lever that is in operable communication with the cam follower, and enabling removal and replacement of the cam by disconnecting the cam from the link, thereby enabling the movement of the breaker mounted spring discharge interlock lever to be altered.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a spring discharge interlock mechanism actuator of switchgear. Electrical codes for switchgears require interlock mechanisms for safety purposes. One such interlock requires that a breaker mechanism charging spring, be discharged whenever the breaker is in a designated location in the switchgear enclosure. This necessitates that the spring be discharged during removal of the breaker from the enclosure at a specific position. One commonly used concept is to incorporate an interlock lever on the breaker that is moved during assembly and disassembly of the breaker from the enclosure. This movement of the interlock lever interfaces with a mechanism that discharges the spring during assembly and disassembly of the breaker from the enclosure at a specific position. 
     A variety of different enclosure designs now exist, having varying amounts of breaker travel, or stroke, to fully rack a breaker. Since breaker mounted spring discharge mechanisms typically receive their actuation movement from the racking stroke, many different spring discharge mechanisms are utilized. These various spring discharge mechanisms also have various actuation strokes as well. Consequently, an easily adaptable system that permits use of various breaker mounted spring discharge mechanisms to be used regardless of a racking stroke of an enclosure would be well received in the art. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Disclosed herein is a method of moving and altering movement of a breaker mounted spring discharge interlock lever during racking and unracking of a breaker with an enclosure. The method includes, rotating a racking screw to rack the breaker into or out of the enclosure, rotating a shaft in operable communication with the racking screw, translationally moving a cam with a link having one end disconnectably connected to the cam and an opposing end disconnectably connected to a crank, that is fixedly attached to the shaft, translationally moving a cam follower that is in operable communication with the cam, moving the breaker mounted spring discharge interlock lever that is in operable communication with the cam follower, and enabling removal and replacement of the cam by disconnecting the cam from the link, thereby enabling the movement of the breaker mounted spring discharge interlock lever to be altered. 
     Further disclosed herein is a breaker spring discharge actuation system. The system includes, an enclosure that is receptive of a breaker having an interlock lever in operable communication with a circuit breaker closing spring, a shaft that is rotatably disposed at the enclosure, a racking screw at the enclosure in operable communication with the shaft, a crank at the shaft, a link that is disconnectably connected to the crank, and a cam. The cam is disconnectably connected to the link and translationally movable such that rotation of the racking screw causes rotation of the shaft that rotates the crank and moves the link connected thereto that translationally moves the cam causing a cam follower to translationally move thereby moving the interlock lever biased thereagainst to allow discharging of the circuit breaker closing spring during racking of the breaker and unracking of the breaker. 
     Further disclosed herein is a method of changing movement of a breaker mounted spring discharge interlock lever that occurs during racking a breaker into and out of an enclosure. The method includes, removing at least one fastener that connects a first link to a first cam and the first link to a crank disposed at the enclosure that is rotatable in response to rotation of a racking screw, removing at least one of the first link and the first cam from the enclosure, placing at least one of a second link in place of the first link and a second cam in place of the first cam into the enclosure, and installing at least one fastener to fasten the first link or the placed second link to the crank and to fasten the first cam or the placed second cam to the first link or the placed second link. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  depicts a perspective view of a breaker installed in a switchgear enclosure in accordance with an embodiment of the invention; 
         FIG. 2  depicts a perspective view of the breaker and switchgear enclosure of  FIG. 1  with a portion of the enclosure housing removed; 
         FIG. 3  depicts a side view of the breaker and switchgear enclosure of  FIG. 2 ; 
         FIG. 4  depicts a side view of the breaker and switchgear enclosure of  FIG. 1  at various levels of assembly into the switchgear enclosure; 
         FIG. 5  depicts a perspective view of the interlock lever actuator disclosed herein; 
         FIG. 6  depicts a reverse angle perspective view of the interlock lever actuator or  FIG. 5 ; 
         FIG. 7  depicts a reverse angle exploded perspective view of a portion of the interlock lever actuator of  FIG. 5   
         FIG. 8  depicts a side view of the interlock lever actuator of  FIG. 5 ; 
         FIG. 9  depicts a side view of the interlock lever actuator of  FIG. 5  in an alternate position of actuation to of that of  FIG. 8 ; 
         FIG. 10  depicts a side view of a cam disclosed in  FIGS. 5-8 ; and 
         FIG. 11  depicts a side view of a cam having an alternate profile than that of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIGS. 1-3 , switchgear  10  having an enclosure  14  is illustrated with a breaker  18  assembled therein through door  22 . A racking cam  26  is rotated, via rotation of a racking screw  30  (since the racking cam  26  is attached to a cross shaft that is rotationally driven by the racking screw  30  as will be described with reference to  FIG. 5 ) that draws the breaker  18  into and out of the enclosure  14 . As the breaker  18  is drawn into and out of the enclosure  14 , an interlock lever  34  is translationally moved by an interlock lever actuator  38  ( FIGS. 5-8 ) according to embodiments of the invention disclosed herein that are described in detail below. 
     Referring to  FIG. 4 , the breaker  18  is shown at four different levels of assembly with the enclosure  14 ; ‘maintenance,’ ‘disconnected,’ ‘test’ and ‘connected.’ At the maintenance level, the breaker  18  is completely removed from the enclosure  14  and is non-operational. At the connected level, the breaker  18  is completely assembled within the switchgear  10  and is fully operational. It is between the two remaining levels; disconnected and test, where embodiments disclosed herein find application. During disassembly of the breaker  18  from the enclosure  14  and specifically during the transition from the test level to the disconnected level, a spring  42  ( FIG. 3 ), which stores energy for actuation of the breaker  18 , is discharged of its energy. Alternately, during assembly of the breaker  18  to the enclosure  14 , and specifically during transition from the disconnected level to the test level, the spring  42  is again discharged. The discharging of the spring  42  is actuated by a spring discharge mechanism  46  that is actuated by translational movement of the interlock lever  34  that is translationally moved by embodiments disclosed herein. Various designs of the spring discharge mechanism  46  are known to those skilled in the art that may require various strokes of the interlock lever  34  to properly actuate. One specific example of a spring discharge mechanism  46  is disclosed in copending U.S. patent application Ser. No. 12/103,075, filed Apr. 15, 2008, incorporated herein by reference in its entirety. 
     With reference to  FIG. 5 , the interlock lever actuator  38  will be reviewed in detail. An operator rotates the racking screw  30  during racking on or racking off of the breaker  18  from the enclosure  14 . The racking screw  30  is attached to the enclosure  14  such that rotation of the racking screw  30  causes a screw block  50 , threadably engaged to the racking screw  30 , to move translationally in a direction parallel with an axis of the racking screw  30 . A pair of connecting links  54  are connected to the screw block  50  at one end and to a pair of cranks  58  at an opposite end. The cranks  58  are fixedly attached to a cross shaft  62  that is mounted to the enclosure  14  by bearings  64  such that it is free to rotate. The foregoing linkages result in rotation of the cross shaft  62  in response to movement of the screw block  50  due to rotation of the racking screw  30 . 
     A second crank  66 , also fixedly attached to the cross shaft  62 , is pivotally attached to a link  70  by a pin  74 . The pin  74  may be any removable pin as is known in the industry, such as a pin with a head on one end and a groove, receptive of a C-clip, on the other end to retain it in bore holes formed in the crank  66  and the link  70 , for example. The opposite end of the link  70  is pivotally connected to a cam  78  by another pin  82 , which may be similar to the pin  74 . The cam  78  is translationally movable in a single axis parallel to an axis of the racking screw  30 . The cam  78  is slidably engaged between a surface  86  and a pin  88  ( FIG. 6 ) in one direction, and between an actuator plate  90  and a portion of a bracket (not shown) within the enclosure  14 . The cam  78  is thereby free to slide in a back-and-forth movement in response to being driven by the link  70 . 
     Referring to  FIGS. 6 and 7 , the cam  78  has a profile  94  on a side, which in this embodiment faces upward, that engages with the pin  88 , which protrudes from the actuator plate  90 . This engagement causes the actuator plate  90  to follow the profile  94  as the pin  88  rides along the profile  94  in response to movement of the cam  78 . As such, the actuator plate  90  follows the profile  94  and moves orthogonally to the movement of the cam  78 . The actuator plate  90  is slidably engaged to a mounting plate  102  with headed pins  106  that engage holes  110  in the actuator plate  90  and slotted holes  114  in the mounting plate  102 . A biasing member  116 , shown herein as a tension spring, biases the actuator plate  90  toward the surface  86  to maintain contact between the pin  88  and the profile  94 . The actuator plate  90  also has a lobe  118  attached thereto that has a profile  122  thereon. Translational movement of the actuator plate  90  and the lobe  118  positions the profile  122  in a location receptive to engagement with the interlock lever  34  during racking of the breaker  18  into and out of the enclosure  14 . 
     Referring to  FIGS. 8 and 9 , the interlock lever  34  includes a pin  126  (or roller) that engages with the profile  122  on the lobe  118 . A biasing member  130 , illustrated herein as a tension spring, biases the interlock lever  34  toward the actuator plate  90  to insure consistent contact between the pin  126  and the profile  122 . The interlock lever  34  includes three slotted holes  138  through which three pins  142  extending from the breaker  18  protrude to orient the interlock lever  34  relative to the breaker  18 . The interlock lever  34  is illustrated in a non-actuated position  146  in  FIG. 8  as can be observed by the relative position of the pins  142  relative to the slotted holes  138 . This is due to the actuator plate  90  being in a non-actuated position  150 , since the pin  88  is not moved by the profile  94  (note pin  88  and profile  94  are shown with dashed hidden lines). The non-actuated position  146  may correlate with the breaker  14  being in the disconnected level, for example, as illustrated in  FIG. 4 . Conversely, the interlock lever  34  is illustrated in an actuated position  154  in  FIG. 9  as can be observed by the relative position of the pins  142  to the slotted holes  138 . This is due to the actuator plate  90  being in an actuated position  158 , since the pin  88  is moved by the profile  94  to a furthest allowable position of travel. The actuated position  154  may correlate with the breaker  14  being in the level between test and disconnected level, for example, as illustrated in  FIG. 4 . Movement of pin  88  from the non-actuated position  150  to the actuated position  158  is due to movement of the cam  78  and link  70  in response to rotation of the cross shaft  62  moving the crank  66  from a crank angle  164  to a crank angle  168 . 
     Referring to  FIGS. 10 and 11 , the cam  78  and link  70  in embodiments illustrated in  FIGS. 5-9  above may accommodate the breaker-racking stroke and the interlock lever  34  actuation stroke for the particular switchgear enclosure  14  and the particular breaker  18 , for example. However, alternate switchgear enclosures may have differing breaker racking strokes and differing breaker interlock lever actuation strokes from those embodied herein such that the cam  78  and the link  70  do not actuate the interlock lever  34  at a position of the racking stroke or an adequate dimension needed to properly actuate the spring discharge mechanism. For example, the cam  78  with the profile  94  and the link  70 , disclosed herein and shown magnified in  FIG. 10 , may provide actuation of the interlock lever  34  relative to the cam  78  at maintenance, disconnected, test and connected levels that correlate with those described in  FIG. 4  above. However, an alternate enclosure and breaker combination may instead require maintenance, disconnected, test and connected levels that correlate with different locations along a cam as shown in  FIG. 11 . In such a situation, an alternate cam and link may be needed. Cam  172  with a profile  176  and link  180 , for example, may satisfy the new requirement. Additionally, other embodiments of cams and links may be utilized for still other enclosure and breaker combinations. Embodiments of spring discharge actuators disclosed herein, therefore, allow for a simple change of a cam and a link through removal of a single pin to accommodate enclosures and breakers with a variety of breaker racking strokes and interlock lever strokes. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, 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 claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.