Open Plenum Array
7
Additional Steps for Initial Start-Up
1. Check for proper wheel rotation by momentarily energizing the fan. Rotation is always
determined by viewing the wheel from the drive side and should correspond to the
rotation decal affixed to the unit.
Note:
One of the most frequently encountered problems with centrifugal fans is motors
which are wired to run in the wrong direction. This is especially true with 3-phase
installations where the motor will run in either direction, depending on how it has been
wired. To reverse rotation of a 3-phase motor, interchange any two of the three electrical
leads. Single phase motors can be reversed by changing internal connections as
described on the motor label or wiring diagram.
2. Arrays with multi-speed motors should be checked on low speed during initial start-up.
3. Check for unusual noise, vibration or overheating of bearings. Refer to the “Troubleshooting” section of this
manual if a problem develops.
R
O
TA
TIO
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Always viewed from
the drive side.
Airfoil Wheel Rotation
Routine Maintenance
Once the unit has been put into operation, a routine
maintenance schedule should be set up to accomplish
the following:
1. Wheel, motor bolts and set screws on the entire fan
should be checked for tightness.
2. Any dirt accumulation on the wheel or in the housing
should be removed to prevent unbalance and
possible damage.
3. Inspect fan wheel and motor, looking for fatigue,
corrosion, or wear.
When performing any service to the unit, disconnect the
electrical supply and secure array wheel.
Operation
All arrays should be run every thirty (30) days, or at least
“bumped” every thirty days. It is preferred that each
array is run as this causes all electrical and mechanical
components to get up to temperature, displacing any
formed condensation, redistributes load on bearings,
and redistributes grease in the bearings (motor and
shaft bearings).
CAUTION
• Always check the fan RPM when adjusting the operating frequency. Do not exceed maximum class fan RPM of
the wheel.
• When operating conditions of the array are to be changed (speed, pressure, temperature, etc.), consult the
factory to determine if the unit can operate safely at the new conditions.
CAUTION
When performing any service to the array, disconnect
the electrical supply and secure wheel.
Vibration
Excessive vibration is the most frequent problem
experienced during initial start-up.
Left unchecked, excessive vibration can cause a
multitude of problems, including structural and/or
component failure.
Many of these
conditions can be
discovered by careful
observation. Refer to
the troubleshooting
section of this
manual for
corrective actions. If
observation cannot
locate the source of vibration, a qualified technician
using vibration analysis equipment should be consulted.
If the problem is wheel unbalance, in-place balancing
can be done providing there is access to the fan wheel.
Any correction weights added to the wheel should be
attached securely.
The factory performs a vibration test on all each array
fan individually. Vibration readings are taken on each
array fan in the horizontal, vertical, and axial directions.
These vibration signatures are a permanent record
of how the fan left the factory and are available upon
request.
Common Sources of Vibration
1. Wheel Unbalance
2. Bearing
3. Mechanical Looseness
4. Drive Component Unbalance
5. Poor Inlet/Outlet Conditions
6. Foundation Stiffness
