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To ensure that the fan motor operates efficiently, with low noise and vibration for a long time, and to extend the life of the bearings and windings, the following standardized maintenance cycle is formulated. (Note: In harsh environments such as high dust, high temperature, and humid conditions, all cycles should be shortened by 50%.)
1、 Daily inspection (every 8 hours of operation/once a day)
Nature: Appearance and sensory inspection, non-stop operation.
Auditory discrimination: During startup and operation, listen for sharp friction sounds, periodic impact sounds, or abnormal electromagnetic buzzing sounds inside the motor and at the bearing seat.
Visual discrimination: Observe whether there are sparks at the motor air outlet (for wound type), whether there is a burnt smell or smoking sign on the cable insulation layer; Check whether the anchor bolts and end cap screws have loosened or slid due to vibration.
Temperature sensation: Touch the motor housing and front and rear bearing end caps with the back of your hand to determine if the temperature rise is abnormal (usually the housing temperature should not exceed the ambient temperature+40 ℃). If local overheating is found, the machine should be stopped immediately for troubleshooting.
2、 Monthly maintenance (every 200 hours of operation/once a month)
Nature: Uninterrupted cleaning and external fastening.
External cleaning: Use compressed air (pressure ≤ 0.3MPa) to blow from the non shaft extension end of the motor towards the shaft extension end, removing dust from the heat sink of the casing, end cover gaps, and fan cover. It is strictly prohibited to use a damp cloth to wipe the junction box area.
Junction box inspection: Open the junction box cover and check if the screws of the wiring terminals are loose. Observe if there is any oxidation or blackening of the copper bars or wires. The relocking torque needs to be consistent.
Belt tension retest (for belt transmission): Check the condition of the pulley wheel, measure the deflection by pressing the midpoint of the belt, and ensure that the tension is moderate. Being too tight will increase the radial load on the bearing, while being too loose will cause slipping and loss of rotation.
3、 Quarterly maintenance (every 600 hours of operation/once every three months)
Nature: Local disassembly inspection and lubrication supplementation.
Bearing grease repair (key process):
Open type bearings: Remove the bearing end cover, remove the waste lubricating grease (butter), clean the bearing chamber, and fill it with new lithium based lubricating grease. The filling amount should be 1/3 to 1/2 of the bearing chamber volume, as excessive filling can lead to poor heat dissipation.
Closed type bearings: No oil is required, but manual turning is needed to check for any weight stagnation during operation. If excessive clearance is found, replacement should be prepared.
Insulation resistance testing:
Use a 500V megohmmeter (for 380V motors) to shake test the insulation resistance of the winding to ground.
Critical value: The resistance in a dry environment should not be less than 2M Ω; if the resistance is less than 0.5M Ω, it indicates that the winding is damp and needs to be dried (such as bulb baking or DC current heating) before operation.
Blade balance inspection: Rotate the fan blades to check if the gap between the blades and the guide ring is uniform, and inspect for cracks in the welds or rivets at the root of the blades.
4、 Semi annual maintenance (every 1200 hours of operation/once every six months)
Nature: Deep maintenance and electrical parameter calibration.
Electrical parameter recording: Use a clamp ammeter to record the three-phase current values during full load operation and compare them with each other. The imbalance of three-phase current shall not exceed 5%. If the deviation is too large, it is necessary to check for power phase loss or winding turn to turn short circuit.
Vibration measurement: Use a vibration meter to measure the vibration velocity (mm/s) in the horizontal, vertical, and axial directions of the motor. If the vibration value exceeds the standard (such as ISO 10816 standard), it is necessary to check the concentricity of the coupling or the dynamic balance of the rotor.
Inspection of contactors and thermal relays: Check for burn marks on the main contacts of the electromagnetic contactor and clean the arc extinguishing chamber; Verify whether the setting value of the thermal relay needs to be fine tuned due to seasonal changes (changes in ambient temperature).
5、 Annual overhaul (every 2400 hours of operation/once a year)
Nature: Comprehensive disassembly, cleaning, and performance recovery.
Disassembly and cleaning: Disconnect the motor from the load and lift it to the maintenance platform for complete disassembly. Use specialized cleaning agents to clean the grease on the surface of bearings, end caps, and rotors.
Bearing replacement standard: Regardless of whether the bearing appearance is good or not, motor bearings that have been running for 2 years (or about 8000 hours) should be forcibly replaced to prevent sudden locking.
Winding insulation strengthening: Measure the absorption ratio (R60/R15). If it is less than 1.3, the winding needs to be immersed in paint and dried, and then coated with insulation coating again.
Mechanical dimension calibration: Measure the air gap (the gap between the stator and rotor). If the difference between the large and small values exceeds 10% of the average value, the worn bearings need to be replaced or the end cap position needs to be adjusted.
6、 Special maintenance for motors that have been out of service for a long time
If the motor is planned to be out of service for more than 3 months, rust prevention treatment is required: apply rust proof grease to the shaft extension end and wrap it with oil paper.
Before resuming operation, a megohmmeter must be used to measure the insulation resistance. If the resistance is too low, it is necessary to run it under low voltage and no-load for 2-4 hours for self drying and moisture removal.
Maintenance records are a very important part of equipment management.
