Cooling tower motor maintenance

Common faults of cooling tower motor

1. The motor does not start

Main reasons:

1）Power supply phase loss or interruption;

2）Poor contact of control circuit;

3）Thermal relay tripping;

4）The motor winding is burnt out.

2. Abnormal heating of the motor

Common factors:

1）Installation is not horizontal, resulting in uneven bearing force on the shaft;

2）Overloading or abnormal fan resistance;

3）Poor cooling or blocked ventilation openings;

4）Bearing oil shortage and damage;

5）Internal short circuit or inter turn short circuit of the motor.

3. Excessive motor vibration and noise

Possible causes include:

1）Fan blade fouling or damage;

2）The coupling between the motor and the fan is not aligned;

3）Bearing wear or looseness;

4）The base shock absorber has failed.

4. Abnormal high current

Common reasons include:

1）Excessive load;

2）Low voltage;

3）Partial short circuit of winding;

4）Abnormal inclination angle of fan blades or poor heat dissipation.

Maintenance steps for cooling tower motor

1. Shutdown and safety measures

1）Cut off the main power supply and hang a warning sign;

2）Check if the environment is safe and ensure that the fan is completely stopped;

3）Use qualified insulation tools.

2. Appearance and basic inspection

1）Check for cracks, water ingress, or corrosion on the motor casing;

2）Confirm that the junction box is well sealed and eliminate loose terminals;

3）Ensure that the motor base is stable, free from rust and deformation.

3. Bearing inspection and replacement

1）Manually rotate the fan and motor coupling to check for smoothness;

2）If there is jamming or abnormal noise, the bearing should be disassembled, cleaned or replaced;

3）Add an appropriate amount of high-temperature lubricating grease to avoid excessive heating.

4. Winding detection

1）Use a multimeter and megohmmeter for testing:

2）Measure the insulation resistance of the winding to ensure it is above 0.5M Ω;

3）Check if the three-phase resistance is consistent;

4）If short circuits or inter turn short circuits are found, the coil should be sent to a professional repair shop for re drying or rewinding.

5. Align the coupling with the fan

1）Adjust the alignment of the motor and fan using a feeler gauge and level gauge;

2）Ensure that the concentricity deviation of the axis is within the allowable range;

3）If it is a belt drive, check the tension of the belt and replace it in groups.

6. Trial operation and performance testing

1）After the repair and assembly are completed:

2）Run the motor without load for 3-5 minutes, observe the temperature rise, noise, and vibration of the motor;

3）Measure whether the three-phase current is balanced;

4）Finally load and run, observe for more than half an hour, and confirm that there are no abnormalities.

Suggestions for maintenance of cooling tower motors

The cooling tower motor operates in a high humidity, high temperature, and high corrosion environment for a long time. Scientific maintenance can effectively extend the service life of the motor, reduce downtime, and avoid a decrease in fan efficiency. The following are standardized maintenance recommendations for cooling tower motors:

1、 Daily inspection (daily/weekly)

1）Observe whether the motor operation sound is normal: no abnormal noise, friction noise, or bearing noise.

2）Check the temperature of the motor casing: Hand touch should not overheat, and if there is a significant increase in temperature, it should be immediately investigated.

3）Confirm that the fan rotates smoothly: there is no obvious vibration or shaking.

4）Check if the current value is normal: The three-phase current should be balanced, and the deviation should not exceed 10%.

2）Observe the internal environment of the cooling tower: keep the area around the motor dry and free of water accumulation.

2、 Monthly maintenance (every month)

1）Clean the dust and debris on the surface of the motor and the heat dissipation holes to avoid poor heat dissipation.

2）Check if the screws of the junction box are loose and ensure that the power supply is firmly connected.

3）Check the motor mounting base and shock absorber pad for looseness, corrosion, and cracks.

4）Check if there is scaling or deformation on the fan blades, and clean or replace them if necessary.

5）Detect the operating voltage, current, and temperature rise of the motor, and record the operating data.

3、 Quarterly maintenance (every 3 months)

1）Check bearing lubrication: Add an appropriate amount of lubricating grease according to the motor model to avoid oil shortage or excess.

2）Check the coupling or belt drive status:

The coupling should be well aligned and free from wear and tear;

The belt is moderately tight and free of cracks, and should be replaced in groups.

3）Check the insulation resistance of the motor, which should generally be kept above 0.5 M Ω.

4）Check the vibration value of the motor, and if it exceeds the standard significantly, check the balance or bearing status of the fan.

4、 Annual maintenance (every 12 months)

1）Fully disassemble and inspect the motor (if conditions permit):

Clean the internal dust and moisture;

Check the insulation of the stator winding and the wear of the bearings.

2）If necessary, replace the bearings or update the lubricating grease (replace all lubricating grease).

3）Conduct a complete electrical inspection: insulation, resistance, current, voltage, phase sequence, etc.

4）Fan turbine dynamic balance correction to reduce motor vibration and bearing load.

5）Check if the motor protection level (IP level) and waterproof measures are still effective.