10 Common Electric Motor Failure Causes & How to Prevent Them

Running an industry or manufacturing unit? Then owning an electric motor is more than just essential. They can power your machineries like pumps, fans and compressors. But, yes, like every other equipment, they are also prone to wear and tear and other operational issues. 

Motor failures happen all the time. Fixing this can be costly and can easily hurt your wallet. The only way to prevent these problems from happening repeatedly is to understand the reasons behind them. This way, you can improve their lifespan and get your equipment to work well.

Let’s explore some of the issues that can lead to a motor failure.    

1. Overheating

This is one of the most common electric motor failure causes. It can easily wear down the insulation around motor windings.

Motor failure due to overheating  can lead to a host of issues like short circuits or even complete breakdowns. 

An important point to be noted in this context  is that – every 10°C increase in operating temperature can bring down an electric motor’s lifespan by half.

What are the Causes of Overheating?

• Restricted airflow – This happens due to poor ventilation. 
• High surrounding temperature – This can easily raise the motor’s running temperature leading to motor failure.
• Overloading of the motor – When loaded beyond its assigned holding power it can lead to a sudden surge in internal heat.
• Dirt accumulation – Blocked cooling ducts or fans due to dirt accumulation can obstruct heat from the motor house to be let out properly.
• Mechanical resistance due to misalignment  – This can create increased drag, forcing the motor to take-in more energy and generate excess heat.  

Prevention Tips:

• Make sure that your electric motor has good ventilation at all times.  This ensures a steady flow of air minimizing the cause of any kind of motor failure.
• The motor should never be overloaded. It should function as per the specifications laid down by the manufacturer. 
• Cooling ducts, fan blades should be kept clean so as to maintain cooling efficiency.
• Thermal overload protection devices should be used to protect the motor against overheating. 

2. Electrical Overload

Electrical overload is something that most electric motors face when it draws in more than its prescribed current. This leads to an increase in the internal heat of the motor which in turn accelerates insulation wear and causes winding damage too. 

 In some cases, excessive current flow can cause severe stress on the windings, making the motor far more vulnerable to failure.

Common reasons for overload:

• When it operates under strong turning power or apparent mechanical load for a long time period. 
• When the motor is not compatible in size for the application at hand.
• Any kind of mechanical hindrances or obstructions in the equipment that is in use.

Prevention tips:

• Choose the right motor that has the right capacity matching the application
• Frequently check the mechanical systems to avoid all kinds of bindings or blockages
• Use overload relays or appropriate electrical protection gears to ensure that the motor stays safe.

3. Bearing Failures

Bearings are critical as they play a huge role in supporting the motor’s rotating rod. They ensure a smooth rotation which in turn reduces downtime and a whole lot of other electric motor failure causes.

Causes of Bearing Failure:

• No lubrication or excessive lubrication to the bearings can lead to friction problems as well as an increase in wear and tear. This ultimately leads to bearing failure and overtime to the electric motor failure. 
• Accumulation of dirt, dust or moisture on the bearings can damage its surface. It can in turn reduce its lifespan. 
• Any installation errors can lead to uneven load distribution and premature wear.
• Stray currents or induced shaft voltages, if left unchecked can cause electrical fluting. This leads to the creation of pits and grooves on bearing races.

If not corrected on time, these issues can lead to excess wear on the bearings, shaft, housing, and other components ultimately resulting in costly downtime.

Prevention Tips:

• Maintain a healthy lubrication schedule. Always use the recommended grease for the bearings. This way you can avoid under or over-lubrication.
• The motor should be kept clean so that dirt of any form does not enter the bearings. Ignoring this can weaken the electric motor’s performance.
• Use bearings that are insulated to prevent them from current-induced damage.
• To ensure even load distribution, the motor shaft should be checked and aligned during installation.

4. Insulation Degradation

Short circuits and current leakages can be avoided to a great extent by using motor winding insulations. But, overtime and on continuous exposure to these current leakages and short circuits, these motor winding insulations can get worn out affecting its efficiency or even its very functioning, which is one of the key electric motor failure causes.

Reasons for Insulation Breakdown:

• Excessive heat and overload leads to faster aging and cracking of insulation
• Any kind of excess moisture on the motor insulation can weaken its strength and even promote electrical leakage.
• Chemical exposure can degrade the insulation material, eventually, weakening its durability.
• Excessive vibration and mechanical stress easily damages insulation layers and creates weak points, which can eventually lead to early motor failure.
• Physical damage during handling, installation, or repairs can weaken winding insulation and lead to premature motor failure.

Prevention Tips:

• Maintain appropriate operating temperatures by using proper cooling and avoiding overloading.
• Ensure that the motor stays dry and make sure to store it in controlled environments. This can prevent condensation and any damage caused by water.
• Use proper sealing in chemical-prone environments by shielding insulation from corrosive agents.
• Perform insulation resistance tests frequently to detect any early deterioration and to avoid sudden failures.

5. Excessive Vibration Issues

This is a problem that needs to be handled well before it becomes a headache. If not fixed within the appropriate time period, it can end up in  accelerated wear on bearings, loosening of components, and damage to winding insulation.

• Vibrations can lead to misalignment of the shaft which may lead to uneven load distribution. 
• Unbalanced rotating parts lead to uneven weight distribution in rotors or impellers creating excessive vibration.
• Loose mounting bolts or structural issues –  inadequate fastening, diagonally positioned mounting bolts, or frame weakness leads to instability during operation. 
• Worn or damaged bearings – wear, pitting, or lack of lubrication in bearings can increase vibration and noise.
• Continuous vibration causes frictional losses, meaning the motor requires additional energy to deliver the same output, which lowers efficiency and speeds up wear.

Prevention tips:

• Fix misalignment issues by using laser alignment tools to position the shaft precisely.  
• Rotors should be balanced during servicing to avoid uneven forces.
• Minimize operational movement by ensuring that the motor is fixed firmly to its mounting base.
• All worn bearings should be replaced on time to avoid future damages and vibration buildup.

6. Moisture and Contamination

This is another way in which electric motors can get damaged. Water, oil, and dust can severely damage electric motors by rusting components, causing electrical malfunction, and damaging insulation.

Sources of contamination:

• If the electric motor operation environment is dusty, moist or chemically harsh, it can easily damage the motor and its components. 
• Lack of quality sealing or inadequate enclosures can lead to motor failure. This is usully caused by debris and other contaminants.
• The motor can face corrosion and internal damage when stored in moist and unclean surroundings.

Prevention tips:

• Choose motors with the correct IP (Ingress Protection) rating to match the operating environment.
• Protective covers or filtration systems should be used to prevent dust, moisture, and chemical exposure.
• Motors should be kept hygienic and in temperature-controlled places when idle.
• Frequently clean the equipment to remove dirt and other contaminants early itself. 

7. Voltage Imbalance and Power Quality Issues

A stable voltage level is a must for motors to function efficiently. Any imbalance here can lead to power quality issues which can in turn cause overheating, reduced torque, and early damage to the winding.

Causes of Poor Power Quality:

• Uneven distribution of load across phases can lead to voltage fluctuations and stress on the motor.
• Improper wiring or any kind of loose connections can cause power loss and excessive heating.
• Harmonics from nearby equipment can distort power supply and reduce the efficiency of the motor.
• Even distant weather events such as thunderstorms or lightning strikes can create sudden voltage disturbances that affect the health of electric motors.

Prevention Tips:

• Voltage should be checked and calculated regularly. Any imbalance that is detected here, should be corrected for smooth operations of the electric motor. 
• All electrical connections should be tightened during the routine maintenance time period. This can avoid excessive heating and electrical discharge.
• It is good to use power conditioners or harmonic filters to reduce power quality disturbances.

8. Shaft Misalignment

If the motor has a misaligned shaft, it is likely to result in an increased mechanical stress. This leads to motor vibration issues and abnormal bearing wear.

Causes of Misalignment:

• Incorrect installation setup methods leading to improper positioning of the motor.
• Constant vibration and changing loads can affect motor alignment and stability. This leads to a shift in the motor base.
• A poor connection between the motor and the associated equipment. This can lead to uneven load distribution.

Prevention Tips:

• Employ precision alignment tools during installation so that the setup is seamless.
• Check alignment continuously to detect and correct any shifts.
• Make sure that the foundation and mounting base are in good condition and do not have any defects.

9. Improper Maintenance Practices

Skipping maintenance or performing it incorrectly can significantly shorten a motor’s service life.

Examples of Poor Maintenance:

• Poor lubrication can lead to an increase in motor friction and acceleration of bearing wear.
• Neglecting to track vibration and temperature trends regularly can lead to overlooking initial signals of mechanical or electrical issues.
• Not attending to peculiar sound or smell which is an indicator of winding damage or component misalignment.

Prevention Tips:

• Develop a preventive maintenance protocol so that problems or errors can be addressed even before they become unmanageable. 
• Use machine diagnostic tools like vibration analyzers and thermal cameras for accurate evaluation. They can help identify potential faults early. 
• Educate technicians on manufacturer-recommended guidelines for proper handling and servicing.

10. Starting and Stopping Too Frequently

Frequent starts and stops put additional stress on a motor’s windings and bearings, generating heat and mechanical shock.

Causes:

• Operational activities that require frequent cycling.
• Incorrect motor type for applications that require large amount of current at start.

Prevention tips:

• Use smooth start controllers or variable frequency drives (VFDs) to minimize mechanical stress.
• Choose motors that have good ratings for frequent starting if necessary.
• Optimize operational sequences to reduce unnecessary stops.

Recognizing Electric Motor Failure Symptoms

Early recognition of electric motor failure symptoms can mean the difference between a quick repair and a costly, extended shutdown. A motor that is beginning to fail often gives subtle warning signs before a complete breakdown occurs.

Key symptoms to watch out for an electric motor failure:

• Excessive noise or vibration – This could mean wear and tear of bearings, instability or even misalignment.
• Excessive heat build up on the motor body – This is mostly due to overloading, poor ventilation, or insulation damage.
• Lacking in performance or torque output – This may be due to a weak operation of windings, bearings, or the power supply, sometimes showing up as insufficient torque during operation.
• Overheated odor from the windings – A key indicator that the insulation is failing or there is an electrical shorting.
• Odd starting behavior – This means a starting difficulty, frequent tripping of circuit breakers, or irregular acceleration.

These warning signs should be taken seriously and steps should be taken to prevent them from escalating into major irreversible failures. A good maintenance program should not only fix problems but also identify the root cause so that recurring failures can be eliminated effectively.

By incorporating routine vibration analysis, thermal scanning, and load monitoring into your maintenance program, you can detect these early warning signs before they escalate into major failures.

Extending the Life of Your Electric Motors

Ultimately, the life of an electric motor stays good if it is well installed, operated, and maintained. Its longevity depends on environmental factors, operational loads, and service practices. 

Best practices to enhance motor lifespan include:

• Track critical vitals – Frequently check key metrics like temperature, vibration, and power quality for any errors.
• Cleanliness should be important – Ensure that your motor stays away from dust, dirt, and moisture as this can easily reduce insulation resistance and cause overheating.
• Lubricating bearings is a necessity – Any lubrication is not what is required. Use the right lubricant prescribed for your motor by the manufacturer at the right intervals.
• Frequently hold inspections and tests – Preventive maintenance is important for detecting errors before they become unmanageable problems. 
• Make sure the alignment and balance are exact – Proper installation prevents premature bearing and shaft wear.

By following these practices, businesses can reduce operational disruptions, lower repair costs, and improve overall productivity.

Ensuring Long-Term Reliability for Your Electric Motors

Electric motors are the backbone of countless industrial operations, but even the most robust units require consistent care to deliver peak performance. 

By understanding the electric motor failure causes and implementing preventive measures, you can maximize uptime, reduce repair costs, and ensure long-term operational reliability.

For businesses seeking expert support, Daniel Group offers comprehensive electric motor diagnostics, repairs, and maintenance services backed by years of industry experience. 

Whether you need immediate fault analysis or a proactive maintenance plan, their skilled technicians and advanced equipment can help keep your operations running without interruptions.

Get in touch today to arrange a professional inspection or discuss a tailored maintenance program designed to protect your motors, minimize downtime, and improve overall productivity.