Appendix C—Automatic Vertical Bus Shutter
Introduction
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Hazard of Electric Shock, Explosion, or Arc Flash
Failure to follow these instructions will result in death or serious injury.
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The automatic vertical bus shutter is an optional feature for the Model 6 motor control center (MCC) vertical bus. The shutters are pre-assembled and installed as part of the MCC line-up.
Automatic bus shutters open and close the vertical bus connection point when units are inserted and removed from the structure. The shutters can be located throughout the MCC and placed in 6 in. (152 mm) increments. They mount to the left edge of each midshelf.
The automatic shutter assembly requires an updated midshelf to allow clearance for the shutter above the plug-in unit.
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MCC structures shipped before January 2003 cannot use the top 3 in. (76 mm) space with the automatic vertical bus shutter option. A 3 in. (76 mm) cover plate is required to cover the opening.
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Compac 6 control units shipped before January 2003 cannot be used with the automatic vertical bus shutter option.
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Variable frequency drive and soft starter units 45 in. (1143 mm) or taller that shipped before July 2003 with a side-panel opening, as shown in Location of Auto-Shutter Cover for Side-Panel Opening, View A, require an auto-shutter cover (Square D Seneca PN 80451765-01). The auto-shutter cover aligns with the back edge of the center-most flat head screw, as shown in Location of Auto-Shutter Cover for Side-Panel Opening, View B.
There are four main components of the automatic vertical bus shutter (see Figure Automatic Vertical Bus Shutter in an MCC (front view)):
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Operator Mechanism: Operates the vertical bus shutter, allowing the plug-in unit to engage the vertical bus.
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Mechanism Housing : Protects the mechanism from incidental foreign material that could obstruct the intended operation.
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Vertical Bus Door and Clip: Provides a barrier against incidental contact with the MCC vertical bus.
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Manual Shutter: Helps prevent access to the unused vertical bus openings. The manual shutter is held in place by a built-in locking feature that holds the shutter in the closed position during shipping, set-up, and daily operations.
Compare the field-installed midshelf to the two designs above. If the field-installed midshelf matches Style 1, follow the installation and removal instructions starting below. If the field-installed midshelf matches Style 2, follow the instructions starting in Installation-style 2.
Installation-style 1
Follow these instructions to install the automatic vertical bus shutter assembly to an existing Style 1 midshelf. See Shelf Installation—Style 1 and Automatic Vertical Bus Shutter Installation—Style 1.
| DANGER |
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hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.
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Position the midshelf (see Shelf Installation—Style 1, A) in the appropriate area of the structure.
Automatic Vertical Bus Shutter Installation—Style 1
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Place the mounting foot (see Shelf Installation—Style 1, B) of the shelf into the mounting pan slots (see Shelf Installation—Style 1, C). Secure the shelf on the left and right with flat head screws (see Shelf Installation—Style 1, Detail A, D).
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Install the hinge leaves (see Shelf Installation—Style 1, Detail A, E) and the door (see Shelf Installation—Style 1, F) into the hinge slots (see Shelf Installation—Style 1, G), which are on the structure corner channel. Fasten the hinge leaves to the structure corner channel using Torx head screws (see Shelf Installation—Style 1, H).
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Install the fastener receptacles (see Shelf Installation—Style 1, Detail B, J) into the bracket slots (see Shelf Installation—Style 1, K) and fasten with Torx head screws (see Shelf Installation—Style 1, H).
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Install the automatic bus shutter assembly by rotating the mechanism housing upward to clear the front corner channel of the structure.
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Slide the automatic shutter assembly upward so that it fits snugly to the left edge of the midshelf.
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Loosely insert the two 10-32 x 3/8 in. mounting screws through the inner left edge of the midshelf and into the square nuts in the housing.
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Remove the manual shutter from the vertical bus assembly. Allow the manual shutter to hang next to the vertical bus assembly.
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Snap the automatic shutter rod onto the vertical bus clip located on the front of the vertical bus assembly.
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Tighten the two 10-32 x 3/8 in. mounting screws inserted in step 8.
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Push the operator mechanism to the rear, ensuring the shutter rotates upward into the pocket of the midshelf above the unit.
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Insert the unit into the MCC. Follow the procedures in Installing the MCC.
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Replace all devices, doors, and covers before turning on the power to the equipment.
Removal-style 1
Follow these instructions to remove the automatic vertical bus shutter assembly from an existing Style 1 midshelf (see Automatic Vertical Bus Shutter Removal—Style 1).
| DANGER |
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Hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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Automatic Vertical Bus Shutter Removal—Style 1
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Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.
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Remove the unit from the MCC structure. Follow the procedures in Installing the MCC.
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Remove the automatic vertical bus shutter rod from the vertical bus clip located on the front of the vertical bus assembly.
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Insert the manual shutter into the vertical bus assembly.
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Remove the two 10-32 x 3/8 in. mounting screws located on the inner left edge of the midshelf.
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Slide the automatic shutter assembly downward, clearing the midshelf.
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Rotate the assembly downward to clear the front corner channel of the structure.
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Remove the automatic shutter assembly.
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Replace all devices, doors, and covers before turning on the power to the equipment.
Installation-style 2
Follow these instructions to install the automatic vertical bus shutter assembly to an existing Style 2 midshelf (see Shelf Installation—Style 2 and Automatic Vertical Bus Shutter Installation—Style 2.
Automatic Vertical Bus Shutter Installation—Style 2
| DANGER |
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Hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.
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Position the midshelf (see Shelf Installation—Style 2, A) in the appropriate area of the structure.
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Place the mounting foot (see Shelf Installation—Style 2, B) of the shelf into the mounting pan slots (see Shelf Installation—Style 2, C). Secure the shelf at the mounting foot end, the left side, and the right side with flat head screws (see Shelf Installation—Style 2, Detail A, D).
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Install the hinge leaves of the door (see Shelf Installation—Style 2, Detail A, E) into the hinge slots (see Shelf Installation—Style 2, G), which are on the structure corner channel. Fasten the hinge leaves to the structure corner channel using Torx head screws (see Shelf Installation—Style 2, H).
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Install fastener receptacles (see Shelf Installation—Style 2, Detail B, J) into the bracket slots (see Shelf Installation—Style 2, K) and fasten with Torx head screws (see Shelf Installation—Style 2, H).
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Install the automatic bus shutter assembly by rotating the mechanism housing upward to clear the front corner channel of the structure.
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Slide the automatic shutter assembly upward so that it fits snugly to the left edge of the midshelf.
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Loosely insert a 10-32 x 3/8 in. mounting screw through the inner left edge of the midshelf and into the square nuts in the housing.
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Remove the manual shutter from the vertical bus assembly. Allow the manual shutter to hang next to the vertical bus assembly.
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Snap the automatic shutter rod onto the vertical bus clip located on the front of the vertical bus assembly.
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Tighten the 10-32 x 3/8 in. mounting screw inserted in step 8.
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Push the operator mechanism to the rear, ensuring the shutter rotates upward into the pocket of the midshelf above the unit.
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Insert the unit into the MCC. Follow the procedures in Installing the MCC.
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Replace all devices, doors, and covers before turning on the power to the equipment.
Removal-style 2
Follow these instructions to remove the automatic vertical bus shutter assembly from an existing Style 2 midshelf (see Automatic Vertical Bus Shutter Removal—Style 2).
Automatic Vertical Bus Shutter Removal—Style 2
| DANGER |
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Hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.
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Turn off all power supplying this equipment before working on or inside the equipment and follow lockout/tagout procedures. Always use a properly rated voltage sensing device to confirm the power is off.
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Remove the unit from the MCC structure. Follow the procedures contained in Installing the MCC.
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Remove the automatic vertical bus shutter rod from the vertical bus clip located on the front of the vertical bus assembly.
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Insert the manual shutter into the vertical bus assembly.
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Remove the 10-32 x 3/8 in. mounting screw from the inner left edge of the midshelf.
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Slide the automatic shutter assembly downward, clearing the midshelf.
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Rotate the assembly downward to clear the front corner channel of the structure.
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Remove the automatic shutter assembly.
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Replace all devices, doors, and covers before turning on the power to the equipment.
Operation-styles 1 and 2
Inserting a Unit
When a unit is inserted into the Model 6 MCC structure, the operator mechanism opens the automatic bus shutter, allowing the unit stabs to connect with the vertical bus.
Removing a Unit
The automatic shutter closes when a unit is removed from the structure. The shutter door provides a barrier against incidental contact with the MCC vertical bus.