This is the third installment of the five-part guide. If you want to learn about the other common causes of motor failure, read more about failures involving bearings, winding, rotor bars, and shaft coupling. 

External conditions are tied for the second most common reason for motor failure. As a motor owner, not only do you have to worry about what condition the motor itself is in, but the environment it is in as well. Knowing how external conditions can damage your motor as well as how to prevent the damage is crucial in maintaining the longevity of the motor. 

Negative external conditions account for 16% of all motor failures. 

The most common external condition issues include:  

• Overheating
• Humidity  
• Contamination  

Overheating 

Some motors can’t take the heat, so don’t put them in the kitchen. If the temperature of your working environment isn’t within the motor’s tolerances, you’re going to have problems. 

To prevent overheating, select a motor designed for the heat it’s going to face. You’ll need high-clearance bearings and an insulation system that offers high levels of protection. Additionally, you could add features like constant cooling fans, cooling coil radiation, and enclosures that will help beat the heat.  

Properly maintain your motor cooling system or it could work against you. Broken fans, clogged vents, or blocked or damaged cooling fins can cause excessive heat buildup and quickly degrade internal wiring insulation. You’ll know you’re too late when you smell the insulation burn up. 

Humidity 

In humid environments, moisture from the atmosphere can enter the motor. Electricity and water are a bad mix! The combination can damage the internal winding and cause corrosion. We’ve also seen folks cause this type of problem by trying to clean out motors with pressure washers.  

Problems with humidity can be abated by opening drain hole plugs, fitting anti-condensation heaters, and utilizing additional corrosion protection (i.e. enhanced paint systems or coatings). If you cannot completely seal against moisture ingress, ensure that the breather plugs are fitted and kept clear so moisture that enters can drain away. 

Contamination 

Any foreign particles that find their way into the motor can cause irreparable damage as they settle into the windings and cause shorts that degrade the insulation.  

It is important to do everything humanly possible to keep any contamination away from the motor to preserve its longevity. If you can’t control the amount of dust in the air, special enclosures with built-in fans can help clear particles from the windings and limit the amount of dust that can reach them. 

Want to learn more about motor failures and solutions? 

There’s an electric motor system for almost any environment if you know where to look. Find the right model and accessories to face the elements and keep your applications powered in any weather. 

You also can read more about common motor failures involving motor bearings, winding, rotor bars, and shaft coupling. 

If you have any questions about how to meet the demands of your motor’s working environment, contact a sales engineer at VFDs.com. You also can email us at info@vfds.com or call 1-855-207-1721. 

Jeremy Butcher

Winding failure is the second most common motor failure. Almost one in five motor failures happens because of stator winding errors. There are a couple of reasons behind stator winding failures. Below is a list of common issues and the solutions to those issues.

This is part three of a six-part series exploring common motor failures and the solutions to preventing or fixing the related damages. This series also covers motor bearings, rotor bars, external conditions, shaft couplings, and an overall summary of common motor failures.

Winding problems account for 16% of all motor failures.

The most common issues with stator windings involve overloading and/or overheating.

Overloading

Overloading the motor shaft causes excessive heat that leads to motor winding failure. Voltage spikes caused by things like VFDs can damage standard motors that aren’t inverter-duty rated. 

VFDs are also used, and programmed to trigger an automatic shutdown in the case of overload, so it’s one of the best overload protection devices you can use. Additionally, the VFD won’t allow a restart if significant damage has occurred, such as melted wires or burned insulation. 

Overheating

The cooler your motor operates, the longer its expected operating life. Overheating impacts the windings first and foremost, because that’s where the motor’s energy is created.

Excessive starts are a major cause of overheating. During startup, a motor has to handle between six to eight times its rated current (when started directly across the line). This can increase the thermal status of the motor, adding to the thermal stress on the windings to the point of failure.

Overheating can also be caused by running a VFD-operated motor too slowly, which in turn decreases the cooling fan speed and allows heat to build up. Overheated windings will put off a burnt smell and start to turn black in spots.

To prevent stator winding overheating, keep a record of your starts and stops, then chart out which motors have problems keeping pace with your daily operation. They may require an upgrade. You can find motors that automatically limit how many starts and stops they can perform within a set timeframe.

Overheating due to slow run speeds can be prevented by adding a constant speed fan that will consistently push air regardless of the motor’s RPM. But the issue lies more with your application than with the motor. The driven equipment has to allow the motor to reach its rated synchronous speed fast enough to prevent overheating, so make sure you’ve paired the right motor with your application before throwing on things like auxiliary cooling fans.

Are your windings ready?

Is your system adequately protected against issues like voltage spikes? Does your team know how to prevent downtime if an overload or overheat occurs?

Be sure to understand the potential issues of overloading and overheating to prevent further problems, and ultimately, prevent motor failure. If you would like to learn more about motor failures and solutions, read our other installments which cover motor bearings, rotor bars, external conditions, and shaft coupling. 
If you have any additional questions, please reach out to our experts at goemc.com, or fill out the contact form below.

Jeremy Butcher

If you’re having problems with motor bearings, you’re not alone.

Bearing failures make up more than half of all electric motor failures globally. Statistics vary widely but anywhere between 35-75% of bearing failures are preventable.

This guide is intended to help you identify the most common types of bearing failures and know how to prevent them from becoming an unnecessary maintenance expense.

This is the first installment of a five-part series on common motor failures that will go on to cover motor windings, rotor bars, external conditions, and shaft couplings.

Bearing problems account for 51% of all motor failures. 

The most common issues with bearings are caused by:

·         Under or overlubricating

·         Mixing or using the wrong type of lubricant

·         Misalignments

·         Shaft overloading

·         Excessive vibrations

·         Overheating

Under or overlubricating bearings

Re-greaseable bearings need regular maintenance to sustain proper lubrication and avoid damaging metal-on-metal contact. Checking your lubrication is especially important after a motor overheating event. 

Check with your motor manufacturer for its recommendations on lubrication intervals and proper practices. Most recommend re-greasing motor bearings after every 2,000 hours of operation or every three months, whichever comes first. Be sure to follow your maintenance schedule and keep records to ensure everything is being performed according to plan. 

Improperly regreased motor bearings are far more likely to fail than those running with outdated grease.

– Motor tip

Overgreasing motors, on the other hand, defeats the general purpose of greasing. Excess grease can build up in the system so thick that it impedes the bearing’s movement, rather than making it easier. It’s like a person trying to use a slip and slide that’s covered in mud. The resulting friction leads to overheating. 

Excess grease can also seep into the windings and cause major electrical and mechanical problems with your motors. 

To prevent overgreasing, begin the re-greasing process by making sure the grease relief valves are open and clear of any dirt or hardened grease. Then remove the grease outlet plug or open the outlet vale and slowly pump grease into the bearing while the motor is running. Add grease slowly or the grease gun could create too much air pressure. Stop greasing if you feel abnormal back pressure building up.

Mixing or using the wrong type of lubricant on bearings

Greases with different base materials won’t blend together, like oil and water. If left unaddressed, one of the greases could harden into a sandlike substance that pulls lubrication away from the bearings. 

Typically, bearing damage will occur before anyone can tell there’s a problem. However, if you find before it’s too late that you’ve used the wrong lubricant, fully purge the grease from the motor then replace it with a different type. The safest bet is to stick the type of grease that the manufacturer recommends on the motor’s nameplate or datasheet so you never risk compatibility problems.  

Misalignment

Motors and applications that aren’t aligned won’t work. Misalignment binds the mechanical connection between the machines, resulting in increased pressure and vibration. Extreme binding can deflect shafts, causing undue stress on bearings and other components. 

When performing your alignments, temperature can be a key ingredient for a successful outcome. Your motor must be aligned under operating temperatures. Machines aligned at room temperature may fall out of alignment once the motor reaches its operating temperature – especially on applications at 3,600 RPM and above. 

While some vibration can be normal, an extreme overnight increase could mean trouble. If this happens, shut the motor down or you could risk malfunction of important components, such as the drive shaft. If you can’t afford to shut it down right away, try and conduct a vibration analysis as soon as possible. Schedule a downtime event based on the results you find.

Misalignment is especially problematic for applications like compressors that usually don’t have soft couplings to alleviate excess pressure. As a best practice, operating and nonoperating alignment should be checked about every 2,000 hours of runtime. Vibration analysis equipment can be used to catch small misalignments before they become big problems.

Shaft overload

Overloading the motor puts more pressure on the shaft, potentially causing belt deflection, increased vibrations, and internal heat. This can break down lubrication and subsequently damage the bearings and shaft. A bearing usually fails before the shaft, but that’s not always the case. 

The only thing to do with an overloaded shaft is shut down and find the source. If you’re experiencing a torsional overload – meaning surplus torque is twisting the shaft – your equipment will most likely shut down automatically. 

Uncouple the application and run the motor by itself. If the motor runs fine, check for binding in the equipment to see if a gearbox, screw compressor, or pump is locking up. 

Perform belt deflection testing for radial overloads due to increased belt loading. Radial overloads are caused by external factors like a drastic change to the output of the driven equipment. 

Excess vibration on bearings

As you’ve likely noticed, excessive motor vibration can be a contributor and/or symptom of various motor failures. If left untreated, excess vibrations can damage every part of a motor, from the shaft to the bearings to the insulation. 

Some vibration is normal, so refer to the severity tolerances set by ISO 10816 to see if your vibration levels are acceptable. Beyond that, you need to know the source of your excess vibration to determine the best solution. 

The simplest solution is to have an expert perform a vibration analysis, determine the root cause, and plan for appropriate service.

Overheating

Bearings must be designed to cope with the environmental temperature of their working environment. 

Bearings are made with tight tolerances. When excess heat reaches the rotor, the shaft expands into the necessary clearance space within the bearing and crowds out lubrication. This creates more friction and eventually destroys bearings. 

Motors run warm to the touch, but if it can burn skin, it’s too hot. If you can smell paint burning, it’s way too hot, and you’re probably about to have a breakdown.

Selecting bearings with more clearance space allows for thermal expansion and higher external operating temperatures. It can increase uptime in multiple ways. You can double the greasing intervals and life of your bearings for every 15 C cooler the motor runs below intended operating temperature. 

You can also add cooling fans to push more air into the motor and dissipate excess heat. 

Find the failure, know the fix

Bearings can go through a lot over the course of a work day. There are many different ways to damage bearings, yet many of the symptoms are the same.

It’s important to know the exact cause of your motor failure to find the right solution. Reach out to us if you need help to protect or repair your motors against bearing failure. Our electric motor experts are ready to answer your questions.

Bearing issues are among many other common causes of motor failure. Read on to learn about possible issues with motor winding, rotor bars, external conditions, and shaft coupling.

If you would like to discuss your maintenance procedure or have questions about how to prevent bearing failures, reach out to a sales engineer at VFDs.com for additional help.

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  Critical Spare Planning
  by Tyler Simmons
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Jeremy Butcher

Motors need to be dependable but if you don’t maintain your motor, you could suffer motor failure. Motors can be expensive to repair and if motors fail it could be a huge loss.

Recognizing your motor’s early warning signs can keep your motor running well and possibly save your motor from failure.  

Have you experienced any excessive vibration, unusual or excessive noise, areas of burnt paint, dirty housing openings, smell of burning, signs of corrosion, signs of excessive wear, a bearing housing that’s hot to the touch, oil and grease leaking from your bearings, or loosening connections? These are warning signs that motor failure may be on your horizon.

Knowing the causes and solutions to common motor problems can be the difference between a working motor or a motor failure so bad that it requires serious repairs or replacement.

Some of the causes of motor failure are hard to detect, or can go unnoticed until it is too late. Awareness at the beginning is important and can save you lots of money on future repairs. This article is the beginning of a series of articles about common motor failures. Click the links below to read more about common motor failure problems, in order from most common to least common:

1.  Bearing failure

2.  Stator winding

3.  External conditions

4.  Rotor bar

5.  Shaft Coupling

Five Most Common Causes of Motor Failure

1. Bearing Failure (51%)

• Insufficient: Re-greaseable bearings need regular maintenance. Most manufacturers recommend re-greasing your motor bearings after every 2000 hours of operation or every three months, whichever comes first. Check with your motor manufacturer for their recommendations on lubricating intervals.

• Excessive Greasing: Excessive greasing can lead to excessive overheating of your bearings which in turn can lead to bearing failure. To ensure that you are not over-greasing your equipment, check that grease relief valves are open during the re-greasing process, make sure that all relief valves are clear of any dirt or hardened grease, remove the grease outlet plug or open outlet valve where fitted, and slowly pump the grease into the bearing. (Grease guns are capable of producing excess PSI and adding the grease slowly can help mitigate this.) Discontinue greasing if any abnormal back pressure is felt.

• Wrong Lubricant: Different types of grease are incompatible with each other due to their chemical makeups. Use only the manufacturer recommended type of grease to avoid any grease incompatibility issues.

• Misalignment: It is essential that your motor and load be correctly aligned under actual operating temperatures and conditions. Machines that are correctly aligned at room temperature may become badly misaligned due to deformation associated with temperature change when in operation. Misalignment should be checked approximately every 2,000 hours of runtime. Both the operating and non-operating alignment should be checked every time you reach this interval.

• Shaft Overload: Excessive loading through the shaft of your motor may contribute heavily to motor failure. Belt driven pulleys often put high loads directly onto the shaft bearing. One way to monitor shaft overload is to keep track of how often your belts are bottoming out – if it is happening more than reasonable – shaft overload is likely the cause.

• Vibration: Excessive motor vibration can be a contributing factor to the failure of many different motor components. Make sure to check that motor mounting bolts are secure, as vibration may cause them to become loose during operation. In order to tell if your vibrational levels are normal, refer to the vibration severity tolerances set out by ISO 10816.    
• Overheating: Before selecting a motor, be sure it is designed to cope with the heat it may be subjected to. Bearings come in a variety of clearances to allow for thermal expansion in operation. For every 15^o C cooler you can keep your motor than normal operating temperature, you can double the re-greasing interval/life of your bearings.

2. Stator Winding (16%)

Winding failure only accounts for 16% of reported motor failures. Winding failure can occur for a few reasons including:

• Overloading: Motor windings can begin to fail due to overloading at the motor shaft which causes excessive heat build-up and eventually motor failure. A thermal overload relay is a common method used to protect against overload.·        

• Overheating: The cooler your motor operates, the longer its expected operating life is. Excessive starts are a major cause of overheating. During start up, a motor typically sees between 6 to 8 times its rated current. This can increase the thermal status of the motor, increasing thermal stress on the windings and contributing to motor failure. One way you can tell if your windings are under stress is to look for darkened areas on the motor windings – these marks are usually signs of overheating.

3. External Conditions (16%)

External conditions contribute heavily to 16% of reported motor failures. External conditions that could ruin your motor include:

• Heat (Motor Operating Temperature): Insulation systems offering high levels of protection against heat are a great idea to prevent against motor failure. Always be sure to maintain your motors cooling system. Broken fans, clogged vents, or blocked or damaged cooling fins can cause excessive heat buildup causing quick degradation of internal wiring insulation.
• Humidity: Electricity and water are a bad mix. High humidity can allow moisture to enter the motor and cause damage and corrosion. Humidity can be combatted by opening drain hole plugs, fitting anti-condensation heaters, and utilizing additional corrosion protection (i.e. enhanced paint systems or coatings). If you cannot completely seal against moisture ingress, ensure that the breather plugs are fitted and kept clear – this will ensure that all moisture that enters can drain away.
• Contamination: Any foreign particles that find their way into the motor enclosure can cause irreparable damage, particularly to motor bearings and windings. Do everything humanly possible to keep any contamination particles away from your motor to preserve its longevity.
• Heat (Ambient Temperature): Before purchasing a motor, be sure that it is rated correctly for the ambient condition in which it will operate. Derating is often necessary for high ambient temperatures whilst extremely low ambient temperatures may require specialized insulating materials.

4. Rotor Bar (5%)

Rotor bar issues contribute to 5% of all reported motor failures. Below we will discuss three ways rotor bar problems can contribute to motor failure:

• Starting Frequency: Heating, cooling, acceleration, and deceleration can cause thermal stress and inertia fractures. Starting time is a function of load torque, inertia, and motor torque. As the starting current is always very much higher than the rated current, an excessively long starting period will cause a harmful temperature rise in the motor.

• Overloads: In a locked rotor or stalled condition the rotor can experience sudden and excessive temperature rise that can cause the rotor cage to fail. Sudden increases in temperature often occur during start-up. Motors can stall during normal operations due to mechanical faults including seized bearings, heavy loading, or possible foreign objects caught in the motor could be possible causes.

• Under Voltage: Under voltage increases running current, causing overheating and a reduction in efficiency – eventually leading to failure.

5. Shaft Coupling (2%)

Shaft coupling problems only account for 2% of reported motor failure. Misalignment and bad installation are two ways shaft coupling issues contribute to motor failure:

• Misalignment: A coupling that is badly aligned suffers some unusual load stresses that can lead to motor failure. Ensure that your coupling is aligned parallel to the shafts.
  • There are three types of misalignment:
    • Mechanical: Experience has shown us that any motor and motor driven load may twist out of alignment during shipping or moving. Proper alignment of direct-coupled drives can be accomplished by a dial-indicator, laser, or computerized instrumentation.
    • Parallel: This is the offset between the centerlines of the two shafts. This can be determined by mounting a dial indicator on one coupling half with the indicator probe bearing radially on the other coupling half, and then rotating both shafts together through 360 degrees.
    • Angular: This is the amount by which the faces of the two coupling halves are out of parallel. This may be determined by mounting a dial indicator on one coupling half with the indicator probe on the face of the other half, and then rotating both shafts together through 360 degrees to determine any variation in reading. During this check, you must keep the shaft of a motor with endplay against its thrust shoulder to prevent false readings due to shaft movements in the axial direction.
• Bad Installation: The biggest cause of coupling failure is due to incorrect mounting. Make sure to research and use the appropriate fitting techniques for your specific motor. There are two main couplings available:
  • Rigid: For use when shafts are coaxially aligned.
  • Flexible or Compensating: For use when shaft alignment cannot be guaranteed or there is expected distortion or movement that could be transmitted through the shaft.

How to Prevent Motor Failure

When installing a new motor, be sure to document the operating condition, machine specifications, and performance tolerance ranges. Make sure to document critical measurements at installation, before and after maintenance and on a routine basis. It is a good idea to create an archive reference of measurements to facilitate trend analysis and identify any change of state or conditions. One way to keep track of your stats is by plotting individual measurements to establish a baseline trend. Any change in this trend line of more than +/- 10% – 20% should be investigated to the root cause to understand why this issue may be occurring and solve the problem before it becomes fatal.

Want to learn more?

If you want to learn more about any of the common motor issues, read our article series that expands on each of these common motor problems listed in this article.

• Bearing failure

• Stator winding

• External conditions

• Rotor bar        
• Shaft coupling

We Specialize in Troubleshooting and Repair of Electric Motors!

Call 800-595-5315 Or Connect With Our Expert Technicians Here:

Other Articles

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  Critical Spare PlanningFebruary 22, 2023
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Jeremy Butcher

When your car begins to make a strange noise, do you wait until you’re stranded on the side of the road to call a mechanic? Not if you know anything about cars. You should get your car to the mechanic as soon as you hear that strange noise, because at that point it will hopefully just be a small fix that won’t cost you too much money. You know as soon as the problem has progressed to the point where you are stranded on the side of the road, your bill has skyrocketed; as well as the time it will take to fix your car will have greatly increased. This is very similar to vibration issues in your equipment. You should be fixing your equipment at the first signs of a vibration issue, to prevent a much more costly issue from occurring down the road.

How do These Systems Work?

In almost all scenarios a sensor is mounted to your machine; this sensor will send the information it collects to a vibration analyzation program either through a cloud collection service, or through a portable data collector, that will read the incoming electrical voltage and generate a time waveform. This will compare the amplitude of vibration versus time. Most analyzers will transform the time waveform into a frequency spectrum using the Fast Fourier Transform process. The frequency spectrum will plot vibration amplitude vs frequency. This allows the technician to detect a wide range of machinery faults earlier than normal and perform any needed maintenance to prevent a critical failure that could result in unscheduled downtime.

Portable Data Collector

These types of vibration monitoring systems must be applied to your machine and then interpreted by a technician each and every time you want to get measurements. A vibration analyst walks-down the critical equipment in your plant and collects vibration data on them using the data collector. The data is then stored on the portable analyzer and is downloaded to a computer where the analyst can perform a detailed vibration analysis. These types of data collecting systems can cost anywhere from $20,000 to $100,000. While this is one of the more expensive options, it can be scaled to fit your exact needs. Some plants will schedule a walk-through once a month, while others will only schedule them twice a year. This type of vibration monitoring can be contracted out or done in house if your staff is willing to be trained. The overall flexibility of this method is what makes it attractive to many business applications.

Wired Monitoring

With these types of monitoring devices, data is continuously uploaded typically every second. Alerts are only sent when issues are identified. You can then connect a computer to this device and log into the system to perform a detailed analysis. Many wired systems have a trip function that can shut off machinery when a certain vibration level is reached. These systems, depending on manufacturer, do have the option of being monitored remotely, or you can opt to have your technician present to download the readings. Wired monitoring systems are very expensive, typically in the hundreds of thousands of dollars price range.

Wireless Monitoring

Every company that sells vibration monitoring systems now has a wireless option. Some are battery powered and some will require a hardwired connection to power. These systems don’t typically gather information quite as fast as wired systems, but will still collect it in a matter of seconds rather than minutes. They vary greatly in cost depending on the manufacturer, but typically cost upwards of $5k-$10k per machine you are monitoring, purely in equipment costs.

Bluetooth Monitoring

This is the newest type of vibration monitoring systems on the market. It will typically only collect data once every five minutes as opposed to every few seconds like other types of monitoring. One of the most popular devices on the market will automatically collect FFT and time waveform data for detailed analysis, but only when the device detects levels in alarm on two consecutive readings. They are, overall, fairly inexpensive. For under $500 you can install the sensor on your equipment and download the application on your phone or tablet to be able to monitor your machinery from close by.

Benefits of Continuous Monitoring

Continuous monitoring is great for catching significant issues before they cause unscheduled downtime; in addition to diagnosing issues that may have already occurred. Machine performance is optimized by monitoring for even the slightest changes and allowing your technicians to correct them in a timely manner. Monitoring of critical and heavy use equipment can protect your bottom line by preventing critical failures. Monitoring difficult to access equipment can keep your maintenance staff safe by allowing them to monitor for issues remotely, rather than scale the side of a building to perform preventive maintenance on your equipment that may be unneeded.

Got More Motor Questions? We Can Help!

Call 800-595-5315 Or Connect With Our Expert Technicians Here:

Other Articles

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  Critical Spare PlanningFebruary 22, 2023
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  The Three Most Common Externally Caused Motor FailuresJuly 14, 2022
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Jeremy Butcher

Medium voltage motors (defined as motors over 1000V) need different protection measures than their lower voltage cousins. Proper motor protection and monitoring in conjunction with a good maintenance schedule will extend the life of your motor and driven application significantly; as well as prevent unscheduled downtime and costly repairs due to easy to prevent failures. Below you will find our three tiers of recommendations for medium voltage motor protection.

Good

• Multifunction Protective Relay
  • Performs motor waveform analysis, detects ground faults, runs rotor and stator temperature predictive algorithms, measures harmonics, resistance temperature detection, zero sequence, differential options, etc., and is programmable to your specific needs.
• Short Circuit Protection
  • Fuses or circuit breakers are permissible.
• Optional: Zero Sequence CT and Resistance Temperature Detection

Better

• Multifunction Protective Relay
  • Performs motor waveform analysis, detects ground faults, runs rotor and stator temperature predictive algorithms, measures harmonics, resistance temperature detection, zero sequence, differential options, etc., and is programmable to your specific needs.
• Short Circuit Protection
  • Fuses or circuit breakers are permissible.
• Resistance Temperature Detection
• Zero Sequence CT
• Optional: Differential CTs, Vibration and/or Shock Pulse Monitoring

Best

• Multifunction Protective Relay
  • Performs motor waveform analysis, detects ground faults, runs rotor and stator temperature predictive algorithms, measures harmonics, resistance temperature detection, zero sequence, differential options, etc., and is programmable to your specific needs.
• Short Circuit Protection
  • Fuses or circuit breakers are permissible.
• Zero Sequence CT
• Resistance Temperature Detection
• Differential CTs
• Vibration and Shock Pulse monitoring

This article is based off our Webinar: Getting the Most out of Your Electric Motor

Got More Motor Questions? We Can Help!

Call 800-595-5315 Or Connect With Our Expert Technicians Here:

Other Articles

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  Critical Spare PlanningFebruary 22, 2023
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  The Three Most Common Externally Caused Motor FailuresJuly 14, 2022
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Jeremy Butcher

A quality motor is a large and expensive purchase. If something goes wrong, you want to make sure that you choose a repair shop that does quality work for a fair price. This article will cover some of the most important things you should look for in your future repair shop.

Quality Motor Inspection & Repair

Your motor repair shop should do a wide variety of tests to ensure that your motor is running the way it is supposed to.

Some of the most critical things your shop should be able to do are:

• Balance the rotors.
• Check for open rotor bars.
• “Mic” the bearing fits.
• Surge test the motor.
• Complete a core loss test and report.
• Cut the bearing races to inspect for fluting or other damage.
• Fully test the motor after repair.
• Do a full tear down and inspection report (large motors only).
• Use green motor practices to preserve and enhance motor efficiency (Be a certified facility).
• Perform all motor repairs in accordance with EASA best practices (Be an accredited facility).
• Use best practices on bearing selection and installation (Be a certified facility for your type of bearing).

EASA Accreditation

Electrical Apparatus Service Association, Inc. (EASA) accreditation is a lot harder to obtain than a simple EASA membership. Accreditation requires strict compliance with EASA’s most stringent standards, including calibration, training, and best practices per EASA AR100. It regularly requires third-party audits of the shop, tools, shipping, and ordering procedures. Energy Management Corporation was the second EASA accredited facility in the United States. Ask your motor shop to see their EASA accreditation certificate. If they can’t show it to you, find another shop!

Green Motors Certification

This certification certifies that the rewind facility follows best practices in preserving motor efficiency, including pre and post wind core tests insuring that core losses are less than 6 watts/lb. Windings must also be tested for maximum efficiency. Green motors certification of your motor is often required for rebates from utilities such as Rocky Mountain Power.

UL Certification

This certification is required for explosion proof motors or any motors used in a hazardous location. In order for a shop to be able to give a motor a UL certification, it must pass a rigorous 51 point inspection. Technicians must go through a special training to be able to give out these important certifications.  

Bearing Manufacturer Certification

Bearing manufacturers offer their own certifications; assuring that your rewind facility employees follow best practices in bearing inspection, handling, installation, and testing. Certifications require manufacturer training and regular facility audits.

If your motor shop can’t prove to you that they have the proper certifications or do a thorough and meticulous job, come visit us at Energy Management. We make sure that each motor that passes through our shop doors is thoroughly inspected, repaired, and returned with the utmost care.

The information for this article came our EMC Webinar: Getting the Most Out of Your Electric Motor

Got More Motor Questions? We Can Help!

Call 800-595-5315 Or Connect With Our Expert Technicians Here:

Other Articles

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  Critical Spare PlanningFebruary 22, 2023
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  The Three Most Common Externally Caused Motor FailuresJuly 14, 2022
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Jeremy Butcher