Common faults and cause analysis of motors

Common faults and cause analysis of motors

Common motor faults can be divided into three categories: electrical faults, mechanical faults, and control system faults. The specific analysis is as follows:

electrical fault
Rotor bar breakage/phase loss
Reason: Long term overload, high temperature operation, or poor line contact can cause the rotor winding conductor to break or be missing.
Features: Sideband harmonics appear on both sides of the frequency of the rotor bar, accompanied by three-phase unbalanced currents when there is a phase loss.
Solution: Use a megohmmeter to test insulation resistance, use a bridge to test DC resistance, and replace damaged windings.

Winding short circuit/grounding
Reason: Insulation aging, poor welding, or external force damage leading to short circuits between adjacent turns, or insulation layer damage causing grounding.
Features: Abnormal fluctuations in current, localized overheating, and possible tripping of protective devices.
Handling: Regularly check insulation resistance, repair or replace short-circuit windings, and check wiring correctness.

Terminal/cable issues
Reason: Loose wiring, cable damage or insulation aging leading to phase loss or short circuit.
Handling: Regularly tighten the wiring terminals, replace damaged cables, and enhance insulation protection.

mechanical failure

Bearing malfunction
Reason: Insufficient lubrication, wear or chemical corrosion leading to bearing jamming or abnormal noise.
Features: Increased high-frequency vibration, elevated bearing temperature, and possible accompanying abnormal noise.
Handling: Regularly lubricate bearings, replace damaged parts, and adjust installation accuracy.

Rotor/stator eccentricity/jamming
Reason: Abnormal operation caused by rotor imbalance, coupling eccentricity, or mechanical jamming.
Features: Increased vibration, abnormal noise, and possible inability to start.
Solution: Adjust rotor balance, check mechanical jamming, and repair eccentricity issues.

Control system malfunction
Abnormal protective device
Reason: Overload, short circuit, or leakage can cause the circuit breaker to trip or the thermal relay to operate.
Solution: Check the load condition, repair the faulty circuit, and reset the protection device.

Controller/signal malfunction
Reason: Controller malfunction or signal transmission error causing abnormal motor operation.
Handling: Regularly maintain the controller, check the signal circuit, and set up safety protection.

preventive measure
Regular maintenance: Check bearing lubrication, winding insulation, wiring status, and replace aging components.
Reasonable load: Avoid overloading operation and control motor temperature rise.
Environmental management: Maintain good heat dissipation and prevent dust accumulation from affecting insulation.

Through system detection and preventive maintenance, the motor failure rate can be effectively reduced and the service life can be extended.