7-1
7. Troubleshooting
7.1 Troubleshooting
Even if the symptoms of failures of the fan are the same, the causes and countermeasures may
be different. There may be two or more causes.
If the cause and countermeasures cannot be determined using the following table, stop the
operation immediately and contact a specialist company or a service center specified by the
manufacturer.
Failure Causes Countermeasures
The bearing
temperature is
high.
Excessive or insufficient grease (oil)
Poor connection between the inner ring and
shaft of the bearing
Poor connection between the outer ring and
the case of the bearing
Deterioration of grease, or entry of moisture
Poor heat radiation from the air-cooling
parts
Poor cooling water conditions, temperature
rise
Excessive tension of the V-belt
Poor alignment of the direct coupling
Adjust it to the proper amount.
Replace the shaft. Replace the motor.
Replace the bearing case. Replace the motor.
Change the grease. Replace the bearing.
Inspect the air-cooling parts. Check ambient
temperature and the conditions of heat
radiation
Inspect the piping of cooling water. Check the
water temperature.
Readjust the V-belt tension.
Correct the alignment of shaft coupling
Strong
vibration
Corrosion or wear in or foreign matter on
the impeller
Poor connection between the boss and
shaft of the impeller
Unbalance of the V-belt pulley
Bend of the shaft
Poor alignment of the direct coupling
Contact between the rotor and casing
Uneven contact of the gland packing
Resonant vibration by improper foundation
Insufficient tightening of the mounting bolt
Damage to the bearing
Remove the foreign matter adhered to the
impeller, and correct the balance of the
impeller.
Replace the impeller or shaft of the motor.
Replace the V-belt pulley, or correct the
balance of the pulley.
Replace the shaft. Replace the motor.
Poor alignment of direct coupling
Reassemble the casing.
Correct the gland packing
Reinforce the foundations.
Retighten the bolt and nut.
Replace the bearing.
Abnormal
noise
Damage to the bearing
Foreign matter intake
Contact between the rotor and casing
Slipping of the V-belt, or contact with the
belt guard
Replace the bearing.
Inspect the inside of the casing.
Avoid the contact between the rotor, casing,
and air intake.
Readjust the V-belt tension, or correct the
position of the guard.
Low
performance
Decrease in rotational speed or frequency
Reverse rotation
Corrosion or wear in or foreign matter on
the impeller
Clogging of the suction filter
Failure in opening/closing of the damper
Dust deposited inside the casing and duct
Excessive resistance
Errors in calculating the specific weight of
gas
Regulate the power supply.
Swap the wires of the motor.
Clean, repair, or replace the impeller.
Clean the suction filter.
Repair the damper.
Clean the casing and duct.
Consider installing a booster fan, or replace the
V-belt pulley.
Measure the specific weight, or perform a gas
analysis.
Motor
overload
Insufficient resistance
Excessive rotation (Belt drive type)
Errors in calculating the specific weight of
gas
Adjust with damper
Replace the V-belt pulley.
Reduce the rotational speed.
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