Abstract:
In a system with two electronic panels arranged with a plurality of busses between them, the removal of one of the electronic panels exposes the live busses to a user. To shield the user from the exposed busses, a mechanism operates shutters to close and cover the busses. The mechanism operation can be based on the rotation of a cam supporting the shutters in the open position. A manual override allows the shutters to be kept in the open position even when the busses are exposed due to the removal of an electronic panel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to a shutter mechanism in an automatic transfer switch system. 
         [0002]    An automatic transfer switch (ATS) is an electrical switch that reconnects an electric power source from a primary to a secondary source. That is, the ATS connects a load to backup power in a case of maintenance or malfunction of the primary power source. A bypass power panel acts as a manual transfer switch and provides redundancy during maintenance or repair to the ATS. The ATS and bypass power panel are typically housed in a frame or rack with a plurality of busses. A shutter mechanism acts as a barrier that prevents a user from coming into contact with a live bus when the ATS is removed. In prior systems, shutter mechanisms have generally moved horizontally across the body of the frame, even when the busses are arranged horizontally. This arrangement presents disadvantages, especially in arrangements with space constraints, because the shutter mechanism must extend beyond the body of the frame. Disadvantages can also arise when the mechanism to operate the shutter lacks consistent movement that mitigates jamming. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0003]    According to one aspect of the invention, a system includes a first electronic panel arranged at a first side of a frame; a second electronic panel arranged at a second side, opposite to the first side, of the frame; a plurality of busses between the first electronic panel and the second electronic panel and configured to be connected to the first electronic panel and the second electronic panel, the plurality of busses being arranged in a first orientation; a shutter arranged to cover the plurality of busses by moving in a second orientation, perpendicular to the first orientation; and a mechanism configured to close the shutter to cover the plurality of busses, the mechanism comprising a cam that rotates to affect movement of the shutter in the second orientation. 
         [0004]    According to another aspect of the invention, a mechanism operates one or more shutters in a system comprising two electronic panels arranged on opposite sides of a plurality of busses that are arranged in a first orientation. The mechanism includes a cam configured to support the one or more shutters in an open position when the two electronic panels are present, the shutters being configured to move in a second orientation perpendicular to the first orientation; a bracket holding the cam, the bracket being configured to move when one of the electronic panels is disengaged from the plurality of busses; and an actuator configured to rotate the cam to release the one or more shutters so that the one or more shutters move in the second orientation to a closed position covering the plurality of busses based on movement of the bracket. 
         [0005]    According to yet another aspect of the invention, a method of operating one or more shutters in a system comprising two electronic panels arranged on opposite sides of a plurality of busses that are arranged in a first orientation includes positioning a cam to support the one or more shutters in an open position when the two electronic panels are present; and rotating the cam to move the shutters in a second orientation, perpendicular to the first orientation, to a closed position covering the plurality of busses when one of the two electronic panels is disengaged from the plurality of busses. 
         [0006]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0007]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0008]      FIG. 1  illustrates a power switching system according to an embodiment of the invention; 
           [0009]      FIG. 2  shows the shutter mechanism from a perspective of the ATS power panel and components of the mechanism according to an embodiment of the invention; 
           [0010]      FIG. 3  shows the shutter mechanism from a perspective of the bypass power panel and components of the mechanism according to an embodiment of the invention; and 
           [0011]      FIG. 4  shows the processes included in controlling the shutters according to an embodiment of the invention. 
       
    
    
       [0012]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0013]      FIG. 1  illustrates a power switching system  100  according to an embodiment of the invention. The frame  105  holds an ATS power panel  110 , a bypass power panel  120 , busses  130 , shutters  140 , and a shutter mechanism  150 . A power switching system  100  is discussed herein as an exemplary system. The power switching system  100  includes an ATS power panel  110  and a bypass power panel  120  (switching panels  110 ,  120 ). However, it is to be understood that the shutters  140  and mechanism  150  are suitable and advantageous for use with any system that includes any type of electronic panels (such as the switching panels  110 ,  120 ) and that benefits from covering live busses  130  during maintenance or replacement of one of the switching panels  110 ,  120 . 
         [0014]    The ATS power panel  110  can be pulled forward, as shown at  FIG. 1 , to remove the ATS power panel  110  from the frame  105  for maintenance or replacement. As  FIG. 1  shows, removing the ATS power panel  110  from the frame  105  leaves the busses  130  exposed. As shown at  FIG. 1 , the system  100  includes three sets of the busses  130  and each of the three sets of busses  130  is arranged horizontally. The exposed live busses  130  can present a hazard to a user accessing the frame  105 . The shutters  140  are shown in the closed position, but when the shutters are open, they reveal the busses  130 . The shutters  140  shown in  FIG. 1  would move down to cover/uncover the busses  130 . The shutters  140  are referred to in the plural because each piece covers a different set of busses  130 . However, as is clearer in  FIGS. 2 and 3 , the shutters  140  may be comprised of a single piece of material with slits cut out to expose each set of busses  130  in the open position. 
         [0015]    The mechanism  150  that operates the shutters  140  is discussed in greater detail below. The mechanism  150  is configured to automatically force the shutters  140  into a closed position (covering the busses  130 ) when the ATS power panel  110  is removed. Specifically, in the embodiment shown at  FIG. 1 , the shutters  140  would move downward to cover the busses  130 . In order to prevent the automatic covering of the busses  130  by the shutters  140 , a manual override of the mechanism  150  is possible. This manual override would be used by a technician who wished to access the busses  130  as part of a system  100  check, for example. Once the ATS power panel  110  is ready to be replaced in the frame  105 , the shutters  140  could be raised by the mechanism  150  to expose the busses  130  so that the ATS power panel  110  could connect to the busses  130 . 
         [0016]      FIG. 2  shows the shutter mechanism (shutters  140 , mechanism  150 ) from a perspective of the ATS power panel  110  and components of the mechanism  150  according to an embodiment of the invention. The components include a cam  151 , bracket  153 , an actuator  155 , and a hole  156 . The actuator  155  causes the cam  151  to rotate from the position shown at  FIG. 2  to close the shutters  140 . The actuator  155  is affected by the motion of the ATS power panel  110  as it gets pulled away and out of the frame  105 . The actuator  155  gets pulled from the bracket  153 , thereby allowing the cam  151  to rotate in a way that pulls down the shutters  140  with its rotation. In this way, the shutters  140  can be closed automatically with the removal of the ATS power panel  110 . If the busses  130  need to be accessed, a pin can be placed through the hole  156  to force the cam  151  to maintain its position and hold the shutters  140  in the open position even if the ATS power panel  110  is removed. This manual override of the mechanism  150  may be used by a technician who needs to check the busses  130  themselves. 
         [0017]      FIG. 3  shows the shutter mechanism (shutters  140 , mechanism  150 ) from a perspective of the bypass power panel  120  and components of the mechanism  150  according to an embodiment of the invention. The perspective illustrated by  FIG. 3  shows the shutter bar  145  resting on the cam  151  when the shutters  140  are in the open position. When the cam  151  rotates down, the shutter bar  145  slides down so that the shutters  140  move down and cover the busses  130 . This downward action of the shutters  140  may be aided by two springs  146 , one on each side of the shutter bar  145 , that extend when the shutter bar is held up by the cam  151  and relax to pull down the shutters  140  when the cam  151  rotates down. To re-expose the busses  130 , in order to re-attach the ATS power panel  110 , for example, the cam  151  can be rotated back up to the position shown by  FIGS. 2 and 3  so that it holds the shutter bar  145  in the open position again. 
         [0018]      FIG. 4  shows the processes included in controlling the shutters  140  according to an embodiment of the invention. At block S 410 , holding up the shutters  140  in an open position includes resting the shutter bar  145  on the cam  151  of the mechanism  150 . This could be seen as a default position when both the ATS power panel  110  and the bypass power panel  120  are in the frame  105 . At S 420 , automatically closing the shutters  140  includes the actuator  155  being moved based on the removal of the ATS power panel  110  from the frame  105  so that the cam  151  rotates down, thereby releasing the shutter bar  145  and closing the shutters  140  over the busses  130 . When the ATS power panel  110  is replaced in the frame  105 , re-opening the shutters  140  at block S 440  includes rotating the cam  151  of the mechanism  150  back up to reposition the shutter bar  145  in a position to open the shutters  140  and expose the busses  130 . Alternatively to automatically closing the shutters  140  upon removal of the ATS power panel  110  from the frame  105 , a pin could be placed in the hole  156  of the mechanism  150  to manually bypass the closing of the shutters  140  upon removal of the ATS power panel  110  from the frame  105  at block S 430 . As shown by  FIG. 2 , the hole  156  is through both the cam  151  and the bracket  153  such that a pin placed in the hole  156  would prevent relative movement between the cam  151  and bracket  153 . 
         [0019]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.