Electric Motor Fault by Component

Electric Motor Fault by Component

Mechanical Component

• Motor
  • Air gap: Eccentricity
  • Bearings: general degradation, local defect (BOR, BIR, BBF, BCF)
• Gearbox
  • Gearwheel: tooth
• Other components: jamming, load, coupling

Electrical Component

• Motor
  • Rotor Faults
  • Stator Faults
• Other components : inverter

Electric Motor Fault by Components

• Motor housing
  • Failures: improper installation, physical damage, corrosion and material buildup.
  • Examples:
    • A soft foot could lead to bearing failures, shaft bending and broken or cracked feet.
    • Material buildup can heat up the operating temperature of the motor, ultimately leading to damage on other parts of the motor, such as bearings.
• Motor stator
  • Failures: physical damage, contamination, corrosion, high temperature, voltage imbalance, broken supports and rewind burnout procedures.
  • Examples:
    • Stator failures occur due to the rewind burnout of the windings lead to damaging the stators by improperly heating the housing and the stator and lead to motor inefficiencies.
• Motor rotors
  • Examples:
    • Shorting between laminated steel and rotor winding. The shorting will lead to thermal stress, physical damage, imbalance, broken rotor bar, contamination and improper installation.
    • Imbalanced motor rotors lead to strain on bearings. This will ultimately lead to a rotor making contact with a stator and creating another point of failure.
• Motor bearings
  • Source: improper handling and storage, improper installation, misalignment, improper lubrication, start/stop processes, contamination, overhung loads and motor fan imbalance.
  • Examples:
    • Contamination lead to bearing failure modes.
    • Lubrication can always be a major cause of failure because there are so many different places where one can improperly apply lubrication. Too much or too little lubrication, along with the improper form of lubrication, can lead to premature wear and tear.
• Motor fans.
  • Motor fans tend to fail from physical damage, ice buildup, foreign materials and corrosion.
    • Examples:
      • The motor fan guard failures can also lead to a larger motor failure because of heat. This tends to happen through physical damage and plugging.
• Motor insulation and windings.
  • Examples:
    • Contamination and moisture can lead to winding failures.
    • Overheating is another issue that can cause a motor failure. Insulation breakdown, cycling and flexing, along with AC drive stress, round out the possible failure modes for this category.
    • The life of the insulation in a standard electric motor is based on the temperature at which the motor operates. This means for an electric motor that is operating at a particularly high temperature, you could be cutting back on its lifespan.
    • Insulation breakdown can be a big problem, as it will cause windings to short out. These problems can be detected through MCE testing and thermography.
    • Winding shorts from turn to turn can crop up from contaminants abrasion, vibration or voltage surges.
• Motor shaft.
  • Motor shaft failure modes occur due to physical damage, improper manufacturing, improper installation and corrosion.
    • Examples:
      • For instance, installing a motor improperly can cause certain components, such as the motor casing, to corrode and create imbalance.

Cross-references

Electric Motor Fault Causes

References

• The 50 Failure Modes of Electric Motors
• The essential guide to electric motor failure