Rockwell Automation Publication 7000-UM202H-EN-P - November 2023 127
Chapter 2 Power Component Definition and Maintenance
Fan Balance
Fan impellers are statically and dynamically balanced within acceptable
tolerances at the factory. Damage in shipping or from poor handling or
installation may upset the fan balance. An impeller that is not properly
balanced can lead to excessive vibration causing undue wear on the entire unit.
If vibration is excessive, shut down the fan and determine the cause.
Some common causes of excessive vibration include:
• support structure not sufficiently rigid or level. Vibration amplified by
resonance in duct work or support structure.
• bearing locking collar or mounting bolts loose. Impeller or bushing loose.
• material accumulation on impeller.
• wheel rubbing on inlet ring.
The inlet ring is the large circular part located on the underside of a horizontal
barrier beneath the fan impeller. The position enables the impeller to sit inside
without touching the ring. The ring sits inside the impeller 10 mm (0.40
inches).
Safety Notes
This procedure requires contact with the internal electrical connectors and
devices. Disconnect all power to the drive before beginning the work. Failing to
do so may result in serious injury or death.
Ensure you can prevent the inlet ring from falling after you have removed all of
the bolts.
If rear panel access is possible, remove rear middle panel of the DC link/fan
portion of the cabinet and remove the inlet ring from the back.
If rear panel access is not possible, follow this procedure:
1. Remove the DC Link barrier and impeller access panel (Figure 105 on
page 123). Remove electrical components in front of the inlet ring access
panel.
2. Remove bolts from the inlet ring; do not to allow the ring to fall.
3. Remove inlet ring via the bottom access panel by moving it around the
DC link and diagonally out the door. You may have to shift the DC link.
4. To install the new ring, reverse the above procedure. Rotate the fan
impeller by hand to check clearance inside the inlet ring.
Move the ring and retighten bolts to eliminate interference.
5. Replace access panels and electrical components.
ATTENTION: To prevent electrical shock, disconnect the main power before
working on the drive. Verify that all circuits are voltage-free using a hot stick
or appropriate voltage-measuring device. Failure to do so may result in
injury or death.
IMPORTANT The fan must not make contact with the inlet ring.
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