Abstract:
An interlocking system for a circuit breaker assembly including a circuit breaker having a plurality of contacts includes a racking screw coupled to the contacts that changes a position of the circuit breaker when engaged by a tool. The interlocking system also includes a front panel defining an opening through which the racking screw is accessible, an access door coupled to the front panel and configured to selectively cover the opening, and an access door stopper coupled to the front panel. The interlocking system also includes a trip assembly coupled to the access door stopper. Each of the access door, the access door stopper, and the trip assembly are moveable between a first position and a second position such that moving to the first position triggers delivery of a trip signal to the circuit breakers to open the plurality of contacts, and wherein, in the second position, the access door is fully open to enable access to the racking screw through the front panel.

Description:
BACKGROUND 
     The field of the disclosure relates generally to power equipment and, more particularly, to a locking mechanism for use with power equipment. 
     Electrical systems, such as power generation, power transmission, power distribution, and power conversion systems, often include switchgear used to control, protect, and/or isolate electrical equipment within the electrical system. Switchgear often serves as connectors between power supplies and power loads to protect and control low voltage circuits. Switchgear generally includes a switch cabinet that houses a switch unit that includes bus bars, electrical cables, circuit breakers, electrical switches, and/or fuses electrically connected in a desired manner to control, protect, and/or isolate the electrical equipment of electrical systems. Circuit breakers generally include contact arms and a trip mechanism coupled together to open the current path in case of a fault detection. The contact arms in circuit breakers are used to close the current path within the breaker. Once the circuit is closed, power flows through the breaker. 
     At least some known circuit breakers include terminals that are permanently coupled to the busbar system within the switchgear cabinet. Some such breakers include draw-out units that are used to provide an option to remove the breaker from the cabinet for servicing without disconnecting the draw-out unit from the switchgear. At least some known for circuit breakers, for example, generally use external locking mechanisms to prevent the carriage assembly from being installed or “racked in” within the switchgear to a service position. For example, at least some known circuit breaker carriage assemblies use a system of gears to facilitate inserting circuit breaker to a service position within the switchgear or to partially withdraw from the switchgear the circuit breakers to a test position. To prevent the circuit breaker from being racked in and receiving power during service, a brake may be provided that engages the gear system. Moreover, some known circuit breaker carriage assemblies use covers, such as switch covers, that prevent the circuit breaker from receiving power during service. Other known circuit breaker carriage assemblies can include a block or stopper that prevents the circuit breaker from being racked in. However, additional parts, such as brakes, covers, padlocks, and/or blocks can be lost or damaged during transport or in storage. Moreover, each of these mechanisms is external to the circuit breaker and/or the carriage assembly, which can lead to damage during use. Accordingly, it is desirable to provide a locking mechanism that is internal to the carriage assembly and does not require additional separate parts. 
     BRIEF DESCRIPTION 
     In one aspect, a method assembling a draw-out breaker assembly including a circuit breaker having a plurality of contacts is provided. The method includes coupling an interlock system to a front panel of a base assembly, and more specifically, coupling an access door to the front panel such that the access door selectively covers an opening formed in the front panel, coupling an access door stopper to the front panel and to the access door, wherein the access door stopper is selectively moveable between a trip position and an open position, and coupling a racking screw to the front panel and to the plurality of contacts. The method also includes coupling a trip assembly to the front panel and to the access door stopper, wherein the trip assembly is selectively moveable between a trip position and an open position, such that i) when the access door stopper is in the trip position, ii) when the trip assembly is moved to the trip position by the access door stopper to engage a trip bar of the circuit breaker, and iii) when the access door is partially opened such that access to the racking screw through the opening is prevented, a mechanical trip signal is provided to the circuit breaker to position the plurality of contacts in an open position, and such that: i) when the access door stopper is moved to the open position, ii) when the trip assembly is moved to the open position by the access door stopper, and iii) when the door is fully opened by the trip assembly to enable access to the racking screw, the position of the plurality of contacts is confirmed. 
     In another aspect, an interlocking system for a draw-out circuit breaker assembly including a circuit breaker having a plurality of contacts is provided. The interlocking system includes a racking screw coupled to the plurality of contacts that changes a position of the circuit breaker within the draw-out circuit breaker assembly when engaged by a tool. The interlocking system also includes a front panel defining an opening through which the racking screw is selectively accessible, an access door coupled to the front panel and configured selectively cover the opening to selectively provide access to the racking screw, and an access door stopper coupled to and at least partially extending through the front panel. The access door stopper is configured to limit movement of the access door based on the position of the plurality of contacts. The interlocking system also includes a trip assembly coupled to the access door stopper. Each of the access door, the access door stopper, and the trip assembly are moveable between a first position and a second position such that moving the access door, the access door stopper, and the trip assembly to the first position triggers delivery of a trip signal to the circuit breakers to open the plurality of contacts, and wherein, in the second position the access door is fully open to enable access to the racking screw through the front panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an exemplary draw-out breaker assembly; 
         FIG. 2  is a perspective view of the draw-out breaker shown in  FIG. 1  with the breaker removed illustrating an exemplary base assembly; 
         FIG. 3  is a perspective view of an exemplary racking system that may be used with the draw-out breaker assembly shown in  FIG. 1 ; 
         FIG. 4A  is a front perspective view of an exemplary interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a rest position; 
         FIG. 4B  is a rear perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in the rest position 
         FIG. 5  is a front perspective view of an exemplary trip interface of the draw-out breaker assembly shown in  FIG. 1 ; 
         FIG. 6  is a front perspective view of the trip interface of the draw-out breaker assembly shown in  FIG. 1 ; 
         FIG. 7  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in the rest position; 
         FIG. 8A  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a trip position; 
         FIG. 8B  is a rear perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in the trip position; 
         FIG. 9A  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in the trip position when the contacts of the breaker are in the open position; 
         FIG. 9B  is a rear perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a trip position when the contacts of the breaker are in the open position; 
         FIG. 10  is another perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a trip position when the contacts of the breaker are in the open position; 
         FIG. 11A  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a trip position when the contacts of the breaker are in the open position and the breaker is locked; 
         FIG. 11B  is a rear perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  in a trip position when the contacts of the breaker are in the open position and the breaker is locked; 
         FIG. 12A  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  when the breaker is between the test and connected position; and 
         FIG. 12B  is a front perspective view of the interlocking system of the draw-out breaker assembly shown in  FIG. 1  when the breaker is between the test and connected position. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of apparatuses are described herein for use in preventing power from being applied to devices, such as a circuit breaker, when the devices are not fully engaged within a draw-out assembly. These embodiments facilitate safer operation of a circuit breaker. The systems, method, and apparatus described herein facilitate a method for racking a circuit breaker in a draw-out breaker assembly. In particular, the systems, method, and apparatus described herein include an interlocking system that provides a trip signal to the circuit breaker to position a plurality of breaker contacts in an open position. To provide the trip signal, the interlocking system is moved to a trip position. More specifically, an access door stopper is actuated to the trip position, which causes an access door to partially open preventing access to a racking screw, and also causes actuation of a trip assembly to the trip position to engage and rotate a trip bar of the circuit breaker to facilitate tripping the breaker and opening the contacts. 
     Furthermore, the interlocking system verifies the position of the contacts to confirm that the contacts are indeed open and that a failure has not occurred. In the event of a failure, a contacts position indicator of the interlocking assembly moves from an open position to a failure position and extends from the breaker into the path of the trip assembly. To verify the position, the interlocking system is moved to an open position. More specifically, the access door stopper is actuated to the open position, which causes actuation of a trip assembly to the open position. If there is no failure and the contacts are open, then the trip assembly moves past and does not contact the contacts position indictor, and the access door is able to fully open allowing access to the racking screw. If there has been a failure and the contacts are closed, the trip assembly will contact the contacts position indicator and prevent trip assembly from further actuation, which prevents the access door from fully opening, therefore preventing access to the racking screw. 
       FIG. 1  is a perspective view of an exemplary draw-out breaker assembly  100  including a circuit breaker  102  and a base assembly  104 .  FIG. 2  is a perspective view of draw-out breaker assembly  100  with breaker  102  removed illustrating base assembly  104 . In the exemplary embodiment, breaker  102  is coupled to base assembly  104  by a first side sheet  106  and an opposing second side sheet  108 . Breaker  102  is removable from base assembly  104  and from a main power circuit (not shown) without requiring disassembly of the fixed connection between breaker connection terminals  103  and a busbar system (not shown) of the main power circuit. Side sheets  106  and  108  are positioned on either side of breaker  102  and facilitate withdrawal of breaker  102  from base assembly  104 . In the exemplary embodiment, base assembly  104  includes a base  110  including a plurality of connection terminals  112 , a plurality of shutters  114 , and a plurality of shutter covers  116 . Shutters  114  cover terminals  112  to protect against access to electrically live components when breaker  102  is removed from base assembly  104 . Base assembly  104  also includes a first side plate  118  and an opposing second side plate  120 , which are both coupled to base  110  on either side of breaker  102  outside of side sheets  106  and  108 . Side plate  120  includes a height adjustment system  122  and a front panel  124 , the height of which is adjustable using height adjustment system  122 . 
       FIG. 3  is a perspective view of an exemplary racking system  126  that may be used with draw-out breaker assembly  100 . In the exemplary embodiment, racking system  126  is coupled to second side plate  120  and includes a racking screw  128 , a racking screw nut  130 , and a cross shaft  132  having a racking cam  134 . Rotational movement of racking screw  128  causes linear movement of racking screw nut  130  on racking screw  128  itself, which causes rotation of cross shaft  132 . Cam  134  is coupled to cross shaft  132  and are engaged with side sheets  106  and  108  (shown in  FIG. 1 ) such that rotation of cross shaft  132  causes rotation of cam  134  to facilitate racking in or racking out of breaker  102 , depending on the direction of racking screw  128  rotation. 
       FIG. 4A  is a front perspective view of an exemplary interlocking system  136  of draw-out breaker assembly  100  in a rest position, and  FIG. 4B  is a rear perspective view of interlocking system  136  in the rest position. In the exemplary embodiment, interlocking system  136  includes a plurality of mechanically linked cams that enable mechanical interlocking of rack-in/out operation. Interlocking system  136  prevent engagement/disengagement of the main circuit while main contacts  103  of withdrawable breaker  102  (shown in  FIG. 1 ) are closed. Once the main contacts  103  of breaker  102  are closed, the operator has no access to racking screw  128 , and, therefore, breaker  102  cannot change its position with respect to draw-out base assembly  104 . 
     In the exemplary embodiment, interlocking system  136  includes a position indication link  138  that is engaged by racking nut  130  (shown in  FIG. 3 ) to provide the operator with a visual indication of the position of breaker  102  within draw-out assembly  100 . Interlocking system  136  also includes a racking access door  140  coupled to front panel  124  to selectively cover an opening defined in the front panel. Interlocking system  136  also includes an access door stopper  142  coupled to and partially extending through front panel  124 . Access door stopper  142  is coupled to access door  140  and limits movement of access door  140 . In the rest position, as described in further detail below, stopper  142  prevents access door  140  from opening to prevent access to racking screw  128  through an opening  141 . When racking access door stopper  142  is pressed in from the rest position, stopper  142  provides a trip signal to breaker  102  and at the same moment releases racking access door  140 , thus providing access to racking access screw  128 . A locking cam  144  is engaged to and driven by position indication link  138  and facilitates locking access door stopper  142  in an activated position to provide a permanent trip signal to breaker  102 . In such a configuration, breaker contacts  103  cannot be closed. 
     Furthermore, interlocking system  136  includes trip assembly  145  including a trip link  146 , an actuation slider  148 , and an actuation cam system  150 . Trip link  146  is mechanically coupled to racking access door stopper  142  and transfers movement of the racking access door stopper  142  to actuation slider  148 . Activation slider  148 , in turn, activates actuation cam system  150  to provide a trip signal to breaker  102  when it is required to open breaker contacts  103  prior to racking of breaker  102  inside draw-out base assembly  104 . 
     In the exemplary embodiment, interlocking system  136  also includes a locking link or padlock slider  152  coupled to a lever link or intermediate lever  154  that allows breaker  102  to be locked only when breaker contacts  103  are open. Locking of draw-out assembly  100  can be executed in two ways: 1) by installing padlocks on padlock slider  152 ; or 2) by using a key-lock  156  with a corresponding key lock latch  158  that hold intermediate lever  154  in the locked position. When draw-out assembly  100  is locked, a permanent trip signal is provided to breaker  102  that prevents breaker contacts  103  from being closed. 
       FIG. 5  is a perspective outside view of an exemplary trip interface  160  of breaker  102 , and  FIG. 6  is a perspective inside view of trip interface  160 . In the exemplary embodiment, trip interface  160  is a component of breaker  102  and includes a trip bar  162 , a trip bar extension  164 , and an actuator  166 . Actuation cam system  150 , which is driven by other components of interlocking system  136 , engages trip bar extension  164  to cause rotation of trip bar  162  within breaker  102 . Rotational movement of trip bar  162  causes linear movement of actuator  166  that acts on a breaker mechanism  168  to trip breaker  102 , causing breaker contacts  103  to open. When trip bar  162  is held in its activated position, a permanent trip signal is provided to breaker mechanism  168 , which prevents closure of breaker contacts  103 . In such a configuration, when breaker contacts  103  contacts are open, a contacts position indicator  170  is withdrawn inside breaker  102  and allows a slider  172  to move up to enable full rotation of actuation cam system  150 . 
     If breaker contacts  103  didn&#39;t open after providing a trip signal to breaker mechanism  168  (failure mode), slider  172  cannot move up, and full rotation of the actuating cams system  150  is not possible, and full movement of racking access door stopper  142  is prevented. In such a case, racking access door  140  cannot be opened such that access to racking screw  128  is prevented and breaker  102  position inside draw-out assembly  100  cannot be changed, thus eliminating the risk of electric shock to the operator. 
       FIG. 7  is a front perspective view of interlocking system  136  of draw-out breaker assembly  100  in the rest position  200 . Referring also to  FIGS. 4A and 4B , in its rest position  200 , components of racking interlocking system  136  in front panel  124  do not act on trip bar extension  164  coupled to trip bar  162 . As such, breaker  102  can be fully operated, that is, breaker contacts  103  can change position (can be either open or closed). Racking access door stopper  142  protrudes out of front panel  124  and can be operated (pressed-in) by the operator. In the case that breaker contacts  103  are closed, contacts position indicator  170  protrudes out from breaker  102 . 
       FIG. 8A  is a front perspective view of interlocking system  136  a trip position  300 , and  FIG. 8B  is a rear perspective view of interlocking system  136  in trip position  300 . Once an operator wants to change position of breaker  102  inside draw-out assembly  100 , racking screw  128  needs to be accessed. To access racking screw  128 , racking access door stopper  142  needs to be moved to the trip position, more specifically, stopper  142  is pressed in to front panel  124  to unlock racking access door  140 . Movement of racking access door stopper  142  is translated through trip assembly  145 , and more specifically, through tripping linkage  146  to actuation slider  148 . As such, moving stopper  142  into the trip position causes movement of trip assembly  145  to the trip position. Sliding of actuation slider  148  results in movement of actuation cam system  150  that engages and acts on trip bar extension  164 . Trip bar  162  rotates as a result and trips breaker mechanism  168  through actuator  166 , thus opening breaker contacts  103 . 
     To trip breaker  102 , only half of the stroke of racking access door stopper  142  is required. In such a configuration, racking access door  140  is still blocked in such a way that it cannot be fully opened and access to racking screw  128  is prevented. As such, a second step, which is positive result of verification of breaker contacts  103  state, is required, as described herein. 
     If breaker  102  is properly tripped (no failure mode, breaker contacts  103  were open), contacts position indicator  170  remains inside breaker  102 , enabling full stroke of racking access door stopper  142  in front panel  124 , as described below. 
       FIG. 9A  is a front perspective view of interlocking system  136  in the trip position  300  when breaker contacts  103  are in the open position,  FIG. 9B  is a rear perspective view of interlocking system  136  in trip position  300 , and  FIG. 10  is another perspective view of interlocking system  136  in trip position  300  when breaker contacts  103  are in the open position. When breaker  102  is tripped and breaker contacts  103  are open, full stroke of racking access door stopper  142  in front panel  124  is possible. 
     Further movement of racking access door stopper  142  to an open position, which is translated through tripping linkage  146  to actuation slider  148  and further to actuation cam system  150  is possible only when breaker contacts  103  are open. In such a state, contact position indicator  170  is positioned inside breaker  102  and does not block movement of slider  172 , which is acted upon by actuation cam system  150  to move passed contact position indicator  170 . Once racking access door stopper  142  is fully pressed in, racking access door  140  can be fully opened providing access to racking screw  128 . 
     When the position of breaker contacts  103  has been verified, a crank, or other tool, can then be inserted into opening  141  to engage racking screw  128  and subsequently rotated to rotate racking screw  128  and change the position of breaker  102  within assembly  100 . 
     In case of a breaker  102  failure, when breaker contacts  103  would not be open, but trip signal was provided to breaker mechanism  168  (e.g. breaker contacts  103  were welded), contacts position indicator  170  will not remain inside the breaker  102 . In such a case, movement of slider  172  on side sheet  108  will be blocked. As a result, a full stroke of racking access door stopper  142  will not be possible, and racking of breaker  102  is prevented. 
       FIG. 11A  is a front perspective view of interlocking system  136  in trip position  300  when breaker contacts  103  are in the open position and breaker  102  is locked, and  FIG. 11B  is a rear perspective view of interlocking system  136  in trip position  300  when breaker contacts  103  are in the open position and breaker  102  is locked. 
     Additional functionality of interlocking system  136  built into front panel  124  is the possibility of locking draw-out assembly  100  such that the position of withdrawable breaker  102  inside base assembly  104  cannot be changed. Safety specifications require that draw-out assembly  100  locking be possible only when breaker  102  main contacts are open and only until breaker  102  reaches its test position (during rack-in). In such a test position, the main contacts of breaker  102  are disconnected from connection terminals  112  in base assembly  104 , the secondary circuit of breaker  102  is connected to base assembly  104  allowing tests to be performed on breaker  102 , and shutters  114  are closed to prevent access to connection terminals  114 . 
     Verification of breaker  102  main contacts position is performed by fully pressing in racking access door stopper  142  in front panel  124 . Once a full stroke of racking access door stopper  142  is possible (which means that breaker main contacts are open), padlock slider  152  can be pulled out from front panel  124  into a lock position. Such movement is possible because racking access door stopper  142  is fully pressed in and is no longer blocking movement of intermediate lever  154 , which engages padlock slider  152  and also moves to the lock position. This displacement of intermediate lever  154  prevents the possibility of opening racking access door  140  such that access to racking screw  128  is blocked. 
     In the above described state, draw-out assembly  100  can be locked by keeping padlock slider  152  pulled out and installing a pad-lock, or by rotating key-lock  156  such that key lock latch  158  engages either intermediate lever  154  or padlock slider  152 . When using key lock  156 , after locking draw-out assembly  100 , the key can be removed. 
       FIG. 12A  is a front perspective view of interlocking system  136  of draw-out breaker assembly  100  when breaker  102  is between the test and connected position, and  FIG. 12B  is a front perspective view of interlocking system  136  breaker  102  is between the test and connected position. 
     When racking access door stopper  142  is fully pressed in into front panel  124 , which is possible only after positive verification that breaker  102  main contacts are open, and breaker  102  racks-in from test position to connected position, or racks-out from connected position to test position, safety requirements necessitate that it be impossible to close the main contacts of breaker  102 . As described herein, the test position is when the main contact system of breaker  102  is disconnected from base assembly connection terminals  112 , the secondary circuit of breaker  102  is connected with draw out base assembly  104  to allow tests on breaker  102 , and shutters  114  are closed to prevent access to connection terminals  112 . Also, the connected position is when the main contact system breaker  102  is connected to base assembly connection terminals  112 , the secondary circuit of breaker  102  is connected with draw out base assembly  104 , and shutters  114  are open to allow access to connection terminals  112 . 
     Such configurations are possible due to cam  144  being engaged with position indication linkage  138 . In between test and connected positions, cam  144 , driven by position indication link  138 , is positioned to keep racking access door stopper  142  in its fully pressed in position such that a permanent trip signal is provided to breaker mechanism  168  and breaker  102  cannot be closed. 
     While racking breaker  102  in or out of draw-out breaker assembly  100 , locking of draw-out breaker assembly  100  is impossible. Once withdrawable breaker  102  leaves the test position, position indication link  138  blocks possibility of intermediate lever  154  rotation. In such a case, padlock slider  152  cannot be pulled out of front panel  124  and a pad-lock cannot be installed, or key-locks  156  cannot be rotated. 
     Exemplary embodiments of apparatuses are described herein for use in preventing power from being applied to devices, such as a circuit breaker, when the devices are not fully engaged within a draw-out assembly. These embodiments facilitate safer operation of a circuit breaker. The systems, method, and apparatus described herein facilitate a method for racking a circuit breaker in a draw-out breaker assembly. In particular, the systems, method, and apparatus described herein include an interlocking system that provides a trip signal to the circuit breaker to position a plurality of breaker contacts in an open position. To provide the trip signal, the interlocking system is moved to a trip position. More specifically, an access door stopper is actuated to the trip position, which causes an access door to partially open preventing access to a racking screw, and also causes actuation of a trip assembly to the trip position to engage and rotate a trip bar of the circuit breaker to facilitate tripping the breaker and opening the contacts. 
     Furthermore, the interlocking system verifies the position of the contacts to confirm that the contacts are indeed open and that a failure has not occurred. In the event of a failure, a contacts position indicator of the interlocking assembly moves from an open position to a failure position and extends from the breaker into the path of the trip assembly. To verify the position, the interlocking system is moved to an open position. More specifically, the access door stopper is actuated to the open position, which causes actuation of a trip assembly to the open position. If there is no failure and the contacts are open, then the trip assembly moves passed and does not contact the contacts position indictor, and the access door is able to fully open allowing access to the racking screw. If there has been a failure and the contacts are closed, the trip assembly will contact the contacts position indicator and prevent trip assembly from further actuation, which prevents the access door from fully opening, therefore preventing access to the racking screw. 
     The systems, method, and apparatus described herein provide a two-step safety feature during breaker rack-in/out movement. In the first step, a trip signal is provided to the breaker to open the main contact system. In the second step, verification that the main contacts of the breaker are disconnected is performed to protect against any potential failure inside the breaker. The system described herein prevents rack-in/out movement of the breaker when its main contacts are closed. It also provides proper logic of the locking system (key-locking and padlocking), such that draw-out assembly can be locked only if the breaker is in proper position in the draw-out assembly (either the disconnected or test position) and ensures the main breaker contacts are open before locking. 
     The order of execution or performance of the operations in the embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention. 
     Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.