Common Failures and Solutions of Gearbox and Electric Motor

The analysis of common failures and corresponding solutions for gearboxes and electric motors is crucial for ensuring the stable operation and extending the service life of equipment. Below is a summary of the typical issues and targeted solutions.

1. Partial Burnout of Electric Motor Windings: Causes and Countermeasures

1.1. Motor Internal Water Infiltration or Exposure to Corrosive Liquids/Gases

Cause: Due to poor sealing, combined with environmental leakage, water or corrosive substances may enter the motor, damaging the winding insulation. This could lead to short circuits between turns, phases, or ground, resulting in winding damage.

Countermeasures:

• Eliminate leakage from the process and mechanical equipment.
• Ensure good sealing of each motor part during maintenance. For example, apply grease to bolts and install splash-proof covers around terminal boxes. If the motor is exposed to liquids or debris, it should be protected with a protective shield.
• For motors operating in such environments, reduce the repair cycle and perform timely overhauls when necessary.

1.2. Bearing Damage or Shaft Deformation (Scraping)

Cause: Damage to the bearings or shaft deformation leads to friction between the stator and rotor, causing an increase in core temperature, insulation failure, and possibly winding short circuits. In severe cases, this can result in misalignment or damage to the stator core, rotor, or end caps.

Countermeasures:

• When disassembling bearings, ensure they are heated to 80°C-100°C using an induction heater or oil bath to ensure proper assembly quality.
• Clean bearings thoroughly before installation, ensuring no debris is left behind. Use clean grease when re-lubricating bearings.
• Minimize unnecessary machining of shafts and end caps.
• During assembly, ensure the stator and rotor cores are aligned properly, avoiding misalignment.
• Maintain a clean motor housing, ensure proper ventilation, and avoid the accumulation of dust in cooling devices. Fan blades should remain in good condition.
• Never mix different types of lubricants.
• Perform a thorough inspection of bearings before installation and replace the grease.
• Motors that have been unused for long periods should undergo a disassembly inspection and grease replacement before use.

1.3. Motor Winding Ends Damaged by Friction with End Caps or Other Components

Cause: Winding ends are subject to damage from friction with the motor’s end caps or other accessories, leading to partial burning of the windings.

Countermeasures:

• When replacing windings, always follow the original winding specifications.
• During maintenance, avoid any rigid contact with the windings. When removing the rotor, ensure it is lifted to prevent friction between the stator and rotor cores.
• Keep any open flame away from the windings and ensure adequate distance between the flame and the windings.
• Before reassembling the motor, carefully check the integrity of the windings.

1.4. Overload or Overheating Leading to Accelerated Insulation Aging

Cause: Continuous overload or overheating accelerates the aging of the winding insulation, leading to carbonization at the weakest points, which can cause short circuits between turns, phases, or to ground, ultimately resulting in partial winding burnout.

Countermeasures:

• Avoid running the motor under overload conditions.
• Ensure the motor is kept clean and has adequate ventilation for heat dissipation.
• Minimize frequent starts, and perform dynamic balancing tests on the rotor when necessary.

1.5. Mechanical Vibration Damaging Motor Windings

Cause: Mechanical vibrations, such as those caused by high current during startup, vibrations from the driven equipment, or imbalance of the motor rotor, can lead to loosening of the winding turns, cracking of insulation, and accelerated aging of the windings.

Countermeasures:

• Avoid frequent starts, particularly with high-voltage motors.
• Ensure the vibration levels of both the driven equipment and motor are within the specified limits.