Filter
Top Products
54 CLCH-IM-16A
5 Bump-start unit and observe the fan wheel for
proper rotation, as indicated by rotation arrow
located on fan housing.
6 Measure the motor voltage and amperage on all
phases to ensure proper operation. The readings
should fall within the range given on the motor
nameplate.
Maximum allowable voltage imbalance is two
percent. Voltage imbalance is defined as 100 times
the sum of the deviation of the three voltages from
the average, divided by twice the average voltage.
For example, if the three measured voltages are 221,
230 and 227, the average voltage would be 226
volts.
The percent of voltage imbalance is then calculated:
100 X {[226-221] + [230-226] + [227-226]}
2 X 226
= 2.2% (Unacceptable)
In this example, 2.2 percent imbalance is not
acceptable and the power company should be
notified to correct it.
q Check unit vibration if the fan speed is changed
more than 5% from the original designed rpm, or if
parts such as shafts, fan wheels, bearings, or
other drive components are replaced. Do not
exceed max. fan rpm.
q Pay particular attention to any vibration, noise or
overheating of the motor and fan bearings.
(Bearings may run warm during break in.)
Excessive Vibration
EXCESSIVE VIBRATION MUST BE CORRECTED TO
PREVENT BEARING AND SHAFT DAMAGE. SEE THE
SECTION TITLED “TROUBLESHOOTING” FOR
DETAILS ON THE COMMON CAUSES FOR VIBRATION.
Determine Fan RPM
Fan rpm can be determined by using a strobe-type
tachometer, or revolution counter.
Sheave Alignment
Align the fan and motor sheaves by using a
straightedge. The straightedge must be long enough
to span the distance between the outside edges of
the sheaves. When the sheaves are aligned, the
straightedge will touch both sheaves at points A
through D to confirm that the shaft is parallel. For
uneven width sheaves, place a string in the center
groove of both sheaves and pull tight. Adjust
sheaves and tighten the sheave set screws to the
proper torque given in
Table 47
.
Figure 45
Proper Drive Alignment
WARNING
Disconnect electrical power prior
to access into a fan or ductwork.
Even when locked out electrically,
fans may cause injury or damage if
the impeller is subject to “wind-
milling.” The impeller should be
secured to physically restrict rota-
tional movement. Failure to secure
impeller can cause severe per-
sonal injury or death.
Fan Belt Alignment
Tighten the belts slightly and rotate the drive several
times.
On multiple belt drives, determine that the force of
deflection is approximately the same on each belt by
pushing each belt in an equal distance at a point
halfway from each sheave. If this force is not the
same for each belt, the motor and fan shaft are not
parallel. Realign as required.
After realignment, tighten the belts again to the
standard belt tensioning specifications. See the
following section.
Center Lines
Must Coincide
Lines Must
Be Parallel
Fixed
Sheave
Fixed
Sheave
Straight
Edge
Straigh
t
Edge
Adjustable
Sheave
A
B
C
D