Patent Publication Number: US-2023146739-A1

Title: Motor control center buckets with interlocked cover-mounted power disconnect switch mechanisms

Description:
RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application No. 63/276,392 filed Nov. 5, 2021, entitled MOTOR CONTROL CENTER BUCKETS WITH INTERLOCKED COVER-MOUNTED POWER DISCONNECT SWITCH MECHANISMS, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     The inventive subject matter relates to motor control center (MCC) units and, more particularly, to switch interlocks for MCC units. 
     Motor control centers (MCCs) typically include a plurality of “buckets,” which are compact modular units that contain various control circuits, such as motor drive circuitry, switchgear, metering devices, and the like. The buckets are typically installed in a larger assembly that includes, for example, AC power buses to which the buckets are connected using spring-loaded “stabs” or similar connector structures. The buckets are typically rectangular enclosures having front panels that may be opened to access the circuitry therein for easy service and removal. MCC buckets may have different sizes depending on the functions and hardware included. 
     SUMMARY 
     Some embodiments provide an apparatus including an enclosure (e.g., an MCC bucket enclosure) having a cover configured to be opened, a disconnect switch positioned in the enclosure, and a shaft having a first end inserted in the disconnect switch and configured to actuate at least one switch in the disconnect switch by rotation of the shaft. The apparatus further includes a switch handle mechanism mounted on the cover, configured to receive a second end of the shaft when the cover is in a closed position, and comprising a switch handle configured to rotate the shaft. The switch handle mechanism may be configured to allow withdrawal of the second end of the shaft from the switch handle mechanism when the switch handle is in a first position to allow opening of the cover and to prevent withdrawal of the second end of the shaft from the switch handle mechanism wherein the switch handle is in a second position to prevent opening of the cover. 
     In some embodiments, the apparatus may further include a locking pin disposed proximate the second end of the shaft. The switch handle mechanism may include a slot configured to allow passage of the locking pin therethrough when the switch handle is in the first position and to prevent passage of the locking pin therethrough when the switch handle is in in the second position. 
     In some embodiments, the switch handle mechanism may include an escutcheon mounted on a front face of the cover and configured to receive the switch handle on a front side of the escutcheon and a link member disposed in an opening of the escutcheon and attached to at back side of the switch handle, the link member having a slotted recess therein configured to receive the second end of the shaft and the locking pin. A rear plate may be attached to a back side of the escutcheon, configured to retain the link member in the opening in the escutcheon and having a slot therein configured to receive the second end of the shaft and the locking pin. The rear plate may be configured to prevent removal of the locking pin therefrom when the switch handle is in the second position. 
     Further embodiments provide an apparatus including a switch handle movable between first and second positions and a mechanism configured to be mounted on a planar surface, mechanically linked to the switch handle and configured to receive an end of a shaft. The mechanism is configured to allow withdrawal of the end of the shaft from the mechanism when the switch handle is in the first position and to prevent withdrawal of the end of the shaft from the mechanism when the switch handle is in the second position. For example, the mechanism may include a slot configured to allow passage of a locking pin proximate the end of the shaft therethrough when the switch handle is in the first position and to prevent passage of the locking pin therethrough when the switch handle is in in the second position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a motor control center (MCC) bucket with a panel-mounted switch actuator assembly according to some embodiments. 
         FIG.  2    is a side view of the MCC bucket of  FIG.  1   . 
         FIG.  3    is a top view of the MCC bucket of  FIG.  1   . 
         FIG.  4    is a front view of the MCC bucket of  FIG.  1    with the front panel removed to show internal components. 
         FIG.  5    is a detailed view of a circuit protector switch assembly and actuator shaft of the MCC bucket of  FIG.  1   . 
         FIG.  6    is perspective view of the circuit protector switch assembly of  FIG.  5   . 
         FIGS.  7  and  8    are exploded views of a front-panel-mounted switch actuator assembly of the MCC bucket of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     Specific exemplary embodiments of the inventive subject matter now will be described with reference to the accompanying drawings. This inventive subject matter may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive subject matter to those skilled in the art. In the drawings, like numbers refer to like items. It will be understood that when an item is referred to as being “connected” or “coupled” to another item, it can be directly connected or coupled to the other item or intervening items may be present. As used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive subject matter. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, items, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, items, components, and/or groups thereof. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
       FIGS.  1 - 4    provide various views of an MCC bucket assembly  100  according to some embodiments. The MCC bucket assembly  100  includes an enclosure  110  with a hinged or otherwise removable cover  120 . Various circuitry is situated in the enclosure  110 . The circuitry may include, for example, metering circuitry  160  that is coupled to a display  170  mounted on the cover  120 . The assembly  100  further includes a disconnect switch assembly  130 , which is actuated by a switch handle assembly  140  mounted on the cover  120 . The disconnect switch assembly  130  is configured to receive power via a set of conductive stabs  150  mounted at a back face of the enclosure  110  and configured to mate with a set of external bus bars. The disconnect switch assembly  130  is configured to switchably distribute power to the metering circuitry  160  and/or other components within the enclosure  110 . 
     Referring to  FIG.  2   , the switch handle assembly  140  is configured to actuate the disconnect switch assembly  130  via a connecting shaft  180  such that switches within the disconnect switch assembly are opened and closed by rotation of the switch handle assembly  140 . As explained in further detail below, the shaft  180  and switch handle assembly  140  may be configured such that the front cover  120  may not be opened to provide access to the interior of the enclosure  110  unless the switch handle assembly  140  is in a position that causes the disconnect switch assembly  130  to be in an “off” state that de-energizes components within the enclosure  110 . 
       FIGS.  5  and  6    provide detailed views of the disconnect switch assembly  130  and switch handle linking shaft  180 . As shown, the disconnect switch assembly  130  includes a switch assembly  134  comprising a plurality of ganged switches, respective ones of which switch respective phases. A rotary actuator mechanism  132  receives the shaft  180  at a port  133  and actuates the ganged switches of the ganged switch assembly  134  responsive to rotation of the shaft  180 . An example of such a disconnect switch assembly is the Bussman Series Compact Circuity Protector line of disconnect switches distributed by Eaton and described in Eaton Technical Data Sheet 10789 (2019). 
     As further shown in  FIG.  5   , the shaft  180  has a locking pin  182  at an end of the shaft  180  distal from the point at which the shaft  180  is inserted into the port  133  of the rotary actuator mechanism  132 . Referring to  FIGS.  7  and  8   , the switch handle mechanism  140  mounted on the cover  120  of the bucket  100  includes a switch handle  142  configured to rotate within an escutcheon  144  that is mounted on a front fact of the cover  120 . A link member  146  is attached to a back side of the switch handle  142  by a first pair of screws and has a slotted recess  145  therein that is configured to receive an end of the shaft  180  and the locking pin  182 . A rear plate  148  retains the link member  146  and is attached to the escutcheon  144  through the cover  120  by a second set of screws. The rear plate  148  includes a slotted opening  149  through which the locking pin  182  of shaft  180  passes to engage the link member  146 . Slots  147  in the opening  149  are designed such that the locking pin  182  of the shaft  180  may pass through the opening  149  when the switch handle  142  is in an “off” position, thus enabling the shaft  180  to be inserted or withdrawn from the switch handle assembly  140  and the cover  120  opened or closed when components fed by the disconnect switch assembly  130  are de-energized. When the switch handle  142  is in an “on” position with the shaft  180  inserted in the link member  146 , however, the locking pin  182  is retained by the rear plate  148 , thus preventing removal of shaft  180  and opening of the cover  120  while the components fed by the disconnect switch assembly  130  are energized. Similarly, if the switch handle  142  is on the “on” position with the shaft  180  removed from the link member  146 , the rear plate  148  prevents insertion of the shaft into the link member  146  and closing of the cover  120 . 
     In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.