When a motor operates with a single phase loss, it will malfunction and may even be damaged. Single-phase operation is usually caused by problems with the power supply line or poor internal wiring. To resolve this, the power supply line needs to be checked to ensure a balanced three-phase power supply, and the internal wiring of the motor needs to be checked to ensure a good connection. Overload faults are one of the most common motor faults, mainly manifested as motor overheating and excessive current. Overload faults may be caused by excessive load, jamming of the transmission mechanism, or improper motor selection. Methods to resolve overload faults include reducing the load, checking the transmission mechanism, and selecting an appropriate motor.
Bearings are a crucial component of motors. Bearing failure can cause sluggish motor operation or abnormal noises. Causes of bearing failure may include poor lubrication, bearing wear, or foreign object intrusion. To resolve bearing failures, it's necessary to regularly check lubrication, replace worn bearings promptly, and ensure the environment around the motor is clean. Windings are a core component of motors. Winding failures can prevent the motor from functioning properly. Winding failures may manifest as insulation aging, short circuits, or open circuits. Resolving winding failures includes regularly checking the winding insulation and promptly identifying and repairing short circuits or open circuits.
Overheating during motor operation can negatively impact its performance and lifespan. Overheating can be caused by excessive load, poor ventilation, or overheating of the windings. To address this, it's necessary to adjust the load appropriately, ensure good ventilation, and regularly check the winding temperature. Motors often exhibit several warning signs before problems arise; timely detection can prevent more serious failures. Below are 10 common warning signs, possible causes, and solutions to help you quickly resolve issues.
1. The motor cannot start.
Symptoms: No response after power is applied, no rotation or sound, or a "buzzing" sound but no rotation.
Possible causes: no power supply, low voltage, poor wiring contact, short circuit or open circuit in the motor windings, or stuck mechanical parts.
Solution: First, disconnect the power and check if the socket and switch have power, and if the wiring is loose; manually rotate the motor shaft to see if it is stuck; if you cannot solve the problem yourself, find a professional to check the windings.
2. Rotation speed fluctuates or is too slow.
Symptoms: Significantly slower than normal speed, or unstable speed during operation.
Possible causes: insufficient lubrication or wear of motor bearings, excessive load (e.g., high resistance from the equipment being driven), or unstable power supply voltage.
Solution: After stopping the machine, add lubricating oil to the bearings and check if the equipment is stuck or has increased the load; use a multimeter to check if the voltage is normal, and if the voltage is low, contact an electrician to check the circuit.
3. Excessive vibration and machine body shaking
Symptoms: The motor vibrates noticeably during operation, and the shaking of the machine body can be felt or seen.
Possible causes: The motor is not securely installed, the coupling (the part that connects the motor and the equipment) is loose, or the rotor is unbalanced (the internal rotating parts are not evenly weighted).
Solution: After stopping the machine, tighten the fixing screws and check if the coupling is loose or worn; if the shaking persists after you handle it yourself, find a technician to check the rotor.
IV. Making abnormal sounds
Symptoms: Abnormal sounds such as "clucking", "buzzing", and "chattering".
Possible causes: lack of lubrication or wear in the bearings, short circuit in the internal windings, or friction between the rotor and stator.
Solution: First, listen for the source of the sound. If the sound is coming from the bearing, add lubricant. If the sound continues or gets louder, immediately disconnect the power and have a professional disassemble and inspect the internal parts.
5. The outer casing is electrified (numbness in the hand).
Symptom: After turning off the power, touching the outer casing causes a tingling or electric shock sensation.
Possible causes: Damaged internal insulation of the motor, or the casing is not grounded or has poor grounding.
Response: Immediately disconnect the power and check if the grounding wire of the casing is loose or detached; do not disassemble the motor yourself, and contact an electrician to inspect the insulation and grounding.
VI. Temperature is significantly too high
Symptom: After running for a period of time, the outer casing gets hot to the touch (normal temperature does not exceed 60℃, and it does not feel hot to the touch).
Possible causes: excessive load, blocked heat vents, broken fan, or short circuit in the windings.
Solution: First, stop the machine to allow it to cool down and clean the dust from the vents; check if the fan is spinning; if it frequently overheats, have a technician check the windings and load.
7. Smoke or a burnt smell
Symptoms: Smoke coming from inside the motor, or a burnt smell (like burning plastic or rubber).
Possible causes: severe short circuit in the winding, burnt insulation material, or overheating and combustion of internal components.
Response: Immediately disconnect the power! This is a serious malfunction; do not continue using it. Contact a professional for repairs immediately to prevent a fire.
8. Weakened power
Symptoms: The original equipment cannot be driven, such as slower speed or lack of power.
Possible causes: damaged windings, stuck bearings, or excessive load.
Solution: Stop the machine and check if the equipment is stuck, increasing resistance; if the equipment is normal, the problem may be internal to the motor and requires professional repair.
9. Deterioration in insulation (more technical, but can be easily assessed)
Symptoms: When measured with an insulation resistance tester, the value is much lower than normal (this can be ignored by ordinary users, and the main judgment is based on the previous symptoms).
Possible causes: water ingress or dampness into the motor, or aging of the insulation material.
Solution: If water gets into the motor, disassemble it, wipe it dry, and then dry it completely; if it is old, the parts or the motor need to be replaced.
10. Abnormal current and power consumption
Symptoms: The current is higher than normal, or the electricity bill increases significantly under the same working conditions.
Possible causes: winding short circuit, bearing wear, abnormal load.
Solution: Ordinary users can observe whether the motor is overheating or making abnormal noises. If so, disconnect the power and check immediately. Do not force it to be used.
Q&A Frequently Asked Questions
[Question] The motor is vibrating slightly, but it can still turn. Does it need to be repaired immediately?
[Answer] If the vibration is not significant and there are no abnormal noises, stop the machine and check if the screws are loose. Tighten them and try again. If the vibration increases or is accompanied by noise, immediately disconnect the power and have a technician inspect it to avoid damage to components.
[Question] My motor is smoking. Can I take it apart and fix it myself?
[Answer] No! Smoke indicates severe internal damage, which may pose a risk of electric shock or fire. The power should be cut off immediately, and a professional repair person should be contacted for assistance. Do not attempt to disassemble the device yourself.
Repeated tripping of protective devices such as thermal relays and circuit breakers strongly suggests an overload, short circuit, or grounding fault in the motor. Do not attempt to force a reset; instead, thoroughly inspect the wiring and mechanical load. In one case, frequent tripping was found to be caused by oxidation of the motor terminals, resulting in excessive contact resistance. The solution was to sand the terminals with fine sandpaper and apply conductive paste.
Prevention and maintenance recommendations
Routine Monitoring: Establish regular records for temperature, vibration, and current, utilizing tools such as infrared thermometers and vibration analyzers for condition monitoring. It is recommended to record data three times per shift to create trend curves for early warning. Regular Maintenance: Clean the cooling ducts every six months and check bearing clearance (using a feeler gauge; if it exceeds 0.1mm, replace the bearing); perform an insulation resistance test and grease replacement annually, removing old grease before replacement. Professional Diagnosis: Complex faults can be precisely located using winding analyzers and current spectrum detection. For example, spectrum analysis can identify the characteristic frequency of broken rotor bars (approximately twice the power supply frequency). Environmental Management: Avoid dust, corrosive gases, or humid environments. Install moisture-proof heaters (suitable for motors with long periods of inactivity; power is generally 1%-3% of the motor's rated power) to maintain winding temperature 5-10℃ higher than the ambient temperature.
