1. First, a visual inspection can identify several abnormal conditions: check if the external fasteners of the motor are loose, whether any parts are damaged, or if the equipment surface is oily or corroded. Also, inspect the contact points and joints for discoloration, burn marks, or smoke stains. These issues may be caused by localized overheating, poor conductor contact, or winding damage. If the voltmeter shows no reading or an abnormal value, it could indicate unbalanced power supply voltage, a blown fuse, uneven three-phase resistance in the rotor, single-phase operation, or poor conductor contact. An ammeter showing excessive current might suggest motor overload, bearing failure, or winding turn-to-turn short circuits. Motor stalling can result from power outages, single-phase operation, low voltage, insufficient motor torque, excessive load, large voltage drops, burned bearings, mechanical jams, etc.
2. Using an auditory rod, you can listen to various noises from the motor, such as electromagnetic noise, ventilation noise, mechanical friction sounds, and bearing noise. This helps in identifying the cause of motor failure. Mechanical causes include bearing failure, mechanical imbalance, loosened fastening screws, improper coupling connections, and rubbing between the stator core. Electrical causes may involve voltage imbalance, single-phase operation, open circuits or breakdowns in the windings, poor starting performance, or inadequate acceleration.
3. By smell, you can detect burnt odors, which may be due to motor overheating, winding burnout, single-phase operation, winding faults, or bearing failures.
4. By touching the motor casing, you can feel if the temperature is too high or if there is unusual vibration. These symptoms may arise from unbalanced mechanical loads, loose components, weak foundation strength, improper coupling, uneven air gaps, debris accumulation, voltage imbalance, winding faults, or bearing issues.
Excessive motor temperature can be caused by overload, blocked cooling ducts, single-phase operation, winding turn-to-turn short circuits, high or low voltage, three-phase voltage imbalance, poor acceleration characteristics, long start-up time, poor contact between the stator and rotor brushes, frequent starts and brakes, reverse braking, high inlet air temperature, or mechanical jams.
When estimating motor temperature by touch, the results can vary based on individual perception and experience.
Routine maintenance inspections are divided into daily checks, monthly or periodic inspections, and annual inspections.
During daily inspections, focus on the lubrication system, appearance, temperature, noise, vibration, and any abnormal signs. Also, check the ventilation and cooling system, sliding friction conditions, and the tightness of all components. Keep detailed records.
Monthly or regular inspections should include checking if switches, wiring, and grounding devices are loose or damaged. Clean dust promptly, inspect lead wires for damage or aging, and test the insulation resistance of the motor windings.
Annual inspections require disassembling the motor to inspect the core, clean grease, and check insulation.
Small, medium, and large repair projects for three-phase asynchronous motors:
1. Small Repair Projects:
- Blow cleaning the motor for general inspection.
- Clean bearings and check/change oil.
- Address local insulation faults in windings, reinforce winding binding, and wrap lead insulation.
- Tighten all screws.
- Adjust and reinforce the fan and fan cover.
2. Medium Repair Projects:
- Include all small repair items.
- Clean the motor, replace local coils, and repair reinforced windings.
- Disassemble and inspect the motor, handle loose coils and wedges, and tighten all parts.
- Perform dynamic balance testing on the rotor.
3. Major Overhaul Projects:
- Include all medium repair tasks.
- Rewind and update all windings.
Motor Model | Overhaul (Year) | Medium Repair (Year) | Minor Repair (Year)
---|---|---|---
Class 1 Y, JB, YSQ, JSQ series and similar models | 7~10 | 2 | 1
Class 2 JRQ, YR, YRQ series and similar models | 10~12 | 2 | 1
Class 3 motors with repeated short-term operation | 3~5 | 2 | 0.5
Large and medium AC motors | 20~25 | 4~5 | 0.5
Regarding the issue with your current motor, it appears that incorrect refueling methods have led to oil accumulating inside the windings. If not addressed promptly, this can severely impact the motor's safe operation and lifespan. Grease buildup affects heat dissipation, increases operating temperature, and slowly corrodes the windings, reducing insulation performance. As the winding temperature rises, it also affects the bearing's operating environment.
Regular maintenance is essential during motor use. We recommend your company pay close attention to these aspects. The recommended solution involves disconnecting the coupling and cooling fan, removing the front and rear end caps, cleaning the windings, washing them with toluene, drying them for one to two hours, and then reinstalling the motor. Finally, reassemble the coupling and perform a test run.
Daily bearing maintenance should strictly follow the guidelines in the "ABB Motor Instruction Manual."
Common issues include lack of maintenance grease, leading to overburning of the stator terminal block, heavy shaft-end load causing short shafts, overly tight belts creating excessive tension, cracks appearing in spiral patterns, metal fatigue, damp bearings causing grease oxidation, rust on the shaft, installation in open areas with large temperature differences, and the motor being prone to "breathing," drawing in moisture.
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