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Common Causes of Motor Failure

Mike Jeffries | November 30, 2020

AdobeStock_17151982.jpegMotors are the beating heart in many industrial environments. They keep conveyor belts running and heavy equipment hard at work. Yet, when not properly taken care of, they are prone to what might seem as abrupt motor failure that'll cease your operations. Understanding the following common causes of motor failure will help you to know when to step in before problems snowball:


  

 

Related Blog: 10 Reasons Why Motor Bearings Fail

Poor Installation Problems

  • Soft Foot: This is a frustrating condition in which the mounting feet of a given motor or driver component aren't even on the mounting surface. This unevenness sets the stage for the issues related to misalignment.
  • Pipe Strain: Unexpected new stresses, such as a foundation shift or striking object, can cause the pipe to strain and misalign.
  • Shaft Voltage: Excessive voltages cause arching across bearing surfaces which contributes to bearing failure.

Power Quality Problems

  • Transient Voltage: Transient external voltages with high amps and frequency can actually erode motor winding insulation. 
  • Voltage Imbalance: Imbalances create excessive current flows that heighten operating temperatures and also lead to insulation tearing.
  • Harmonic Distortion: While some harmonic distortion is to be expected, too much can cause the excess energy to circulate throughout the windings and decrease the motor's overall efficiencies and increase internal temperatures.

Mechanical Problems

  • Misalignment: If the motor drive shaft isn't in correct alignment with its load, then misalignment occurs that causes premature wear on the mechanical drive components.
  • Shaft Imbalance: When the center of mass on a rotating part doesn't lie on the axis of rotation it causes a 'heavy spot' that leads to aforementioned premature wear and tear.
  • Shaft Looseness: This occurs wherever there is excessive clearance between mechanical components and can lead to accelerated wear precipitating motor failure.
  • Bearing Wear: We've written at length about the importance of keeping motor bearings in prime condition. Failed bearings lead to increased dragging, overheating, and lower working efficiency that all accumulate to create accelerated wear and breakdown.

Variable Frequency Drive Problems

  • Inconsistent PMW Signals: Pulse width modulation controls a motor's output voltage and frequency. Inconsistent signaling leads to the erosion of motor winding insulation.
  • Sigma Current: These are stray currents that can cause circuits to trip and impair operations.
  • Operational Overloads: When a motor is under excessively high loads it causes premature wear on the sensitive electrical and mechanical components not built to accept those loads.

 

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Topics: industrial motor repair, motor repair, motor failure, industrial motor, motor bearings

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