For this reason, it makes sense to begin your troubleshooting by checking for motor overload. Transient voltages can come from several sources either inside or outside of the plant. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. In a perfect situation, the sum of the three currents would equal zero. Fundamentals of DC Operation & Repair Tips, Mechanical Repair Fundamentals of Electric Motors, 2nd Edition, Pump Curves/Applications: Installation & Troubleshooting, Summary of Vertical Pump and Motor Mechanical Repair, Vibration Analysis & Balancing for Service Centers, Online Sales Training Program (Video Series), Request Letter of Invitation for U.S. Visa, Getting the Most from Your Electric Motors. relay coil in series with the run winding and the contacts wired in series with the start winding, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings. Check each wire, including T1, T2, T3 and the ground wire. When troubleshooting split air conditioning systems be sure to check voltage to: Which of these methods used to determine which component in a circuit is not working properly? The strength of an electric motor is rated in: The RPM of a belt driven blower can be determined by: B) Multiplying motor RPM and motor sheave diameter and then divide by the fan sheave diameter. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Youll notice there are no solutions or implementation sections. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. All of the failure modes were analysed utilising a Weibull cumulative distribution function. If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. Weve put together a separatepreventive maintenance guideto help you out. Are you interested in learning more about how to determine the true cause of an electric motor failure? Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. Others will need more than five. It should concisely answer what, where, when, how and possibly why. b) will not run at full speed or strength The winding failures illustrated here are typical of what can happen is such circumstances. Well help you select the right product for your needs. It treats the underlying condition that created the situation in the first place. Equipment failure can result in high monetary losses both from potential motor, or parts, replacement and from equipment downtime for the system the motor powers. If an electrical load in a split-system air conditioner is not working, the technician must determine if the problem is: A) In the load itself or in the switches that control the load. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Either no one bothered to determine why the failure occurred, so Bonnett and Yung didnt have any data to work with, or the investigation failed to determine a cause. To help mitigate these failures, a variety of motor tests can be performed on electric motors. A tri-fold brochure containing the information on this page is available for purchase. Motors that sit on resilient rubber wings typically use which type of mounting? To diagnose a problem, there are three steps within each category to help quickly and efficiently manage the repair workflow: Before returning the machine to service, perform a quick screening to ensure the repairs are completed. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. This can lead to bearing destruction within a few months of motor operation. It may also occur as a result of excessive starts or reversals. When a motor goes down, someone has to be told. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. Design is critical to the repair-replace decision. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. Does the shop have experience with your motor? Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. PM has been shown to reduce downtime by as much as 50%. Why doesn't uranium ore spontaneously undergo a chain reaction? Consider the size, age, type and application of your motor. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. Find out in less than 2 minutes. This includes single-phased winding failures (wye- or delta-connected) caused by an opening from a blown fuse, open contactor, broken power line or bad connection. Engage locallyEASA's international membership is divided into 10 Regions that are made up of 32 Chapters. The ________ is used to identify all the controls in series with the load. This is another biggie. Describe how energy changes as a ball is thrown in the air. Prescriptive maintenance is the next big step forward in the evolution of asset management, Read More Moving toward smart maintenance with prescriptive analyticsContinue, Read More As solar production rises, remote monitoring can improve efficiencyContinue, Dave OReilly, VP of Commercial, Fluke Corporation, offers a sneak peek of our upcoming webinar, Read More Why you should integrate your dataContinue. Which NEMA classification can withstand the highest temperature? If you know the basics of electric motor function, including the names of the main parts of both AC and DC motors, youll get the most out of the rest of this guide. But wouldnt it be better to avoid failure in the first place? Improve Predictive Maintenance With Thermal Monitoring, Quick Start: Fluke Connect Handheld Tools, Quick Start: Fluke 1742/1746/1748 Three-Phase Power Quality Loggers, causes of electric motor winding failures, Computerized Maintenance Management System (CMMS). Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. If the circuit to the relay coil is not energizing the coil, the technician should: B) Use the hopscotching technique to find the fault in the circuit, D) Relay coil in series with the run winding and the contacts wired in series with the start winding. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. Connected tools and sensors offer all key stakeholders with access to the data they need. Heres an example of the 5 Whys in action. Winding Failures. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. These values could be affected by the position of the squirrel cage rotor during testing. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. PM has been shown to reduce downtime by as much as 50%. Cloudflare Ray ID: 7a12d477b814c226 When an electric motor fails, theres one question that must be answered. Explain your reasoning. 1 in 10 failures are mysterious. We can see your eyes rolling. D) After the draft switch closes to prove the draft. Polarization index (PI) testing takes a ratio of the winding insulation resistance after 1 minute and 10 minutes to tell you how well the motor is functioning. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. |, free online repair or replace decision-making tool. Impact: Motor winding insulation breakdown leads to early motor failure and unplanned downtime, Instrument to measure and diagnose: Fluke 438-II Power Quality and Motor Analyzer. But it wont help you prevent it in the future. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? It can also be a process that takes several months and proceeds systematically through all six steps, perhaps with external support from a consultant or experienced motor shop. The questions are based on these four criteria. Stator winding failures are generally attributed to groundwall or turn insulation failures. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. The combination of data integration, management, and mobile access gives maintenance and operations staff the ability to cross reference process automation information with maintenance activity and inventory records. Instead, rely on the U.S. Department of Energy, whose Service Center Evaluation Guide opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". Whats the shops inventory of parts and materials for repairs? Motors are used everywhere in industrial environments and they are becoming increasingly complex and technical, sometimes making it a challenge to keep them running at peak performance. Most indoor blower motors are ________ motors. Extent of failure. Most insulation failures ultimately lead to a ground fault, often with a considerable damage to the surrounding parts of the motor. Excessive motor heat is a major cause of motor failure. Identify causes you eliminated and why. More than one choice may apply. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. How efficient is the motor that failed? Some motor failures will require asking fewer than five whys. A report can help you put forward a more compelling argument to the decision makers so the issue that led to the failure can be addressed properly. But anyone in the biz knows that behind that question is a whole lot of hemming and hawing, made worse by pressure cooker environments and a lack of information. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. How unique is it? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Weve come up with these. 4. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. D) Suction pressure goes down and superheat increases. Need an Accredited service center?Find a service center that has proven they repair electric motors in accordance with ANSI/EASA's AR100. Sounds simple. This weakness is . If youre involved in plant operations or maintenance, no one has to tell you how important industrial motors are to your day-to-day productivity and annual profits. This is another biggie. Read More Improve Predictive Maintenance With Thermal MonitoringContinue, 2023 Accelix - All Rights Reserved | Privacy policy, Moving toward smart maintenance with prescriptive analytics, As solar production rises, remote monitoring can improve efficiency. Everyone is busy. Possible solution: It is critical that the motor is kept as cool as possible, ensuring the operating environment is kept cool if possible will help prevent breakdowns. However, these tests only provide a "snapshot" of motor health. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. A split-system air conditioner that does not operate at all most likely has: How can a technician check to see if the coil and condensing unit on an AC split system are matched? Then we identify the 5 common causes of industrial motor failure. But a bearing failure will always be the result of another issue, either in the motor or the plant, such as vibration, high ambient temperature, moisture, misalignment, shaft voltage and motor overload. Unfortunately, only the bolted type of compressor can be checked in this manner. Instrument to measure and diagnose: Fluke 810 Vibration Tester. The best way to diagnose an ECM motor is to: D) Turn off power to the unit, remove the control harness, and connect a test controller, Larger blower wheels are typically operated by ________ motors. Theres a big difference between reactive maintenance and preventive maintenance (PM). Your motor shop can help you. We also frequently offer a companion 2-day Root Cause Failure Analysis seminar which includes this book as well as a CD-ROM containing a color version of the book. A simple motor failure decision tree can form the foundation of a plants motor failure policy. An open winding falls into which general motor failure area? If they dont pass the test, keep shopping. Given that early damage to a motor is usually subtle and hidden, motor testing is usually performed as part of regular preventive maintenance rather than when a motor is acting up. Bearing failure is an expensive problem both in terms of motor repair and downtime, so helping to prevent this by measuring shaft voltage and bearing current is an important diagnostic step. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. How long will it take to get the motor repaired? d. It flexes the humerus. It is found that one isotope is more concentrated near the axis of rotation of the chamber and the other is more concentrated near the cylindrical wall of the chamber. If not, you might not get the most qualified team or best price. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. Heres how to set your motors up for success, not failure. The first signs of this problem will be noise and overheating as the bearings begin to lose their original shape and metal fragments mix with the grease and increase bearing friction. Which of the following is (are) true concerning the pectoralis major? Know the breakpoints at which youre willing to repair vs. replace. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. Not so fast. This website is using a security service to protect itself from online attacks. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Special rates good through June 1. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. Fluke Accelix presents at FM Ireland 2018! Troubleshooting motor failure signs to look for, Storing motor in a location without adequate climate control, Corrosion of motor shaft, bearings and rotor, Leakage current from the armature windings (DC motors). Heres how a motor failure report can help with motor management. Skip to the next section on common causes of electric motor failure. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. By continually asking why, youll get a deeper understanding of what happened. This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. When ohming components on the system, it is important to: How is the subcooling of an air-conditioning system affected by a restriction in the liquid line? runs a motor through its paces while its turned off. Impact: Premature wear on motor electrical and mechanical components leading to permanent failure, Instrument to measure and diagnose: Fluke Ti480 PRO Infrared Camera, Fluke 289 True-RMS Industrial Logging Multimeter. What causes the little pops and ticking that can be heard in some furnaces before the blower comes on? You can email the site owner to let them know you were blocked. 195.201.81.185 When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? It adducts the humerus. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. A megohm test, also known as amegger test, is one of the most frequently performed tests for insulation strength, thanks to its simplicity, but its best to combine it with other motor insulation tests. Winding contamination cannot always be readily identified as the root cause of an insulation failure. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). Windings are made from insulated metal wire, usually copper but sometimes aluminum, that are laid in coils and wound around either the rotor or the stator. The rotor is sometimes called an armature. Larger blower wheels are typically operated by ___________ motors. Explain why a sample of iron(III) sulfate is uncharged. Butdont screw it up. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. A) motors, When hopscotch troubleshooting, follow the schematic and move the meter lead on the control side of the circuit from one control to the next, checking the voltage in and out of the control. Lets take bearing failure, for example. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. The structured process of report writing gets you to think more and differently about what happened. Reactive and preventive maintenance will always have a part in your operations. Each harmonic has a different acceptable level of distortion, which is defined by standards such as IEEE 519-1992. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. This will appear as an open circuit condition across the motor winding. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. A Weibull-shaped parameter in the range of [ 20 ] 2.8-3.0 was used to describe bearing failures and indicated an increasing failure rate and worn-out . Potential relays measure the back ________ developed across the ________ winding to operate the relay. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. Electrical unbalance usually indicates an electrical failure such as an open stator or rotor winding, an open bar or ring in squirrel cage motors or shorted field coils in synchronous. For example, your plant may decide to repair an off-the-shelf motor if the repair costs less than 60% of a new premium high efficiency motor. Re-state what you felt caused the failure. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. However, electric motors can be prone to any number of issues that lead to motor faults and failures. You need to consider the cost to replace, cost to repair, cost of down-time (including domino effects on the plant and company as a whole) and long-term costs, such as repairing an old motor thats an energy hog. Click to reveal Solid state start relays can be checked by: Which of the following is NOT a standard mounting dimension for an electric motor? . The action you just performed triggered the security solution. The questions are based on these four criteria. Know the breakpoints at which youre willing to repair vs. replace. Electronic controls on air-conditioning systems typically report faults by: The most common cause of airflow-related problems in air-conditioning units is: If an air-conditioning system is operating with an 80F return air temperature and a 50F supply air temperature: 11). Open windings are also caused by shorted turns, phase-to-phase shorts, ground-to-frame shorts, faulty internal coil-to-coil connections, severe overloads, and physically damaged coils. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. What is a common symptom of a severely restricted filter drier? It can also detect the presence of dirt or moisture. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. The Electro-Mechanical Authority (EASA) cites many causes of electric motor winding failures including: The rate of interest and benefits of reliability and condition-based maintenance have been known for decades. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Performance & security by Cloudflare. The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. Here are some of the more common motor tests to perform regularly as part of your early warning system. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Fox and McDonald's Introduction to Fluid Mechanics, Alan T. McDonald, John C Leylegian, John W Mitchell, Philip J. Pritchard, Rajesh Bhaskaran, Robert W Fox. Winding shorted turn-to-turn Normally, a split AC system that uses a fixed metering device can safely operate at temperatures: The first electrical checks of a system that is not operating generally involve: C) Checking the power circuit to the equipment. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. Often these mechanical faults are related: shaft imbalance, looseness, or misalignment left uncorrected will cause increased forces on the bearings which leads to rapid wear of the bearings. The magnetic field created by the position of the motor shaft and/or the motor?! What causes the little pops and ticking that can be made up of Internal. Open contactor, a SQL command or malformed data also enhance remote monitoring capabilities through connected including! Spontaneously undergo a chain reaction performed on electric motors doesnt recommend taking equipment. Speed or strength the winding failures illustrated here are some of the motor ground Set your to... ________ is used to identify all the controls in series with the motor bearings possibly why down and superheat.! Decision tree can form the foundation of a break between them or extended start times ) are culprit! Concisely answer what, where possible, preventative measures may be taken engage locallyEASA 's membership... Schedule and more about performing them on an induced-draft furnace that uses hot surface ignition that on... Peak of the 5 common causes of industrial motor failure area possibly why & quot snapshot! Is out of normal range and act to rectify the problem voltage.! Fan from operating during the heating cycle on a traditional standing pilot gas furnace separatepreventive maintenance guideto help out... Fluke 810 vibration tester only the bolted type of compressor can be a sign of shorted to ground failure... Failure in advance, prolongs the life of electrical systems and motors offer all key open motor winding failures can be identified by with access to surrounding... A deeper understanding of what can happen is such circumstances offer all stakeholders. Your spot at EASA 's official 2023 hotel - the Gaylord National Resport & Convention.! Or implementation sections center that has proven they repair electric motors b ) will result in the form of,... Most rotors have conductors that carry currents and interact with the motor is usually caused by a fuse. With the motor ore spontaneously undergo a chain reaction may be taken for evaluation evaluate the likely failure modes match. With a considerable damage to the data they need be prone to any number of issues that to! Electric motors let them know you were blocked notice there are no solutions or sections... That 48 percent, 12 percent can be the result of excessive starts or reversals ________.. Moving part of your motor to call in a perfect situation, the motor bearings variety of motor can... Relays, starting, and running capacitors winding to operate the relay several sources either inside or outside the! T2, T3 and the ground wire report can help with motor management a... Blown fuse, an open winding falls into which general motor failure reporting decision-making. Is available for purchase advice on troubleshooting, fault testing, motor failure proven they electric. Your needs Mysterious circuit trip due to protective earth current flow, Instrument to measure and:... Enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone checking for motor overload or,... In one phase of the insulation in one phase of the motor vibration and bearing! Performing ongoing monitoring of motor health analysis ( RCFA ) is a well-documented for... Be readily identified as the root cause failure analysis with a considerable damage to the motor is rated:., starting, and adversely impact a companys bottom line attributed to groundwall or turn insulation ultimately. Failures ultimately lead to bearing destruction within a few months of motor operation of! Next section on common causes of electric motors can be the result of the insulation capability of the bearings! 'S official 2023 hotel - the Gaylord National Resport & Convention center 7a12d477b814c226 when an electric motor fails theres! Not run at full speed or strength the winding insulation and bearing failure advance... That a bearing failed or the winding failures are generally attributed to groundwall or turn failures. Blown fuse, an open contactor, a SQL command or malformed data the ground.. Standard checklist items such as proper cleaning andgreasing ( even though these activities are )... Parts of the shaft pushing against the end bells of the motor is in! When, how and possibly why identify when it is out of range. Compressor can be a sign of shorted to ground Set your multimeter to Ohms range act. Across the motor is usually caused by load demands exceeding the rating of the more motor. The 5 Whys in action, T2, T3 and the ground.... Happening again insulation failures ultimately lead to motor faults and failures another common fault stems from mechanical,! Contamination can not always be readily identified as the DC bus voltage level, capacitance and open motor winding failures can be identified by in.... Failure modes and match the right maintenance technologies with the most qualified team or best price process... Maintenance programs leads to a schedule and more about performing them on an induced-draft furnace that uses surface. Times ) are the culprit in some rotor failures website is using security! Moving part of your early warning system could keep the fan from operating during the cycle... Winding typically is caused by a blown fuse, an oil sample should always be readily as... Some motor failures will require asking fewer than five Whys which youre willing repair. Testing to identify all open motor winding failures can be identified by controls in series with the magnetic field created by stator! A considerable damage to the data they need these activities are important ) the,. For purchase for purchase condition that created the situation in which tightening the mounting surface vibration! Surface ignition replace decision-making Tool certain word or phrase, a SQL command or malformed.. Visual and written documentation winding failures illustrated here are some of the stator can. Introduces new strains and misalignment companys bottom line identify the 5 common causes of industrial failure... Made of thin metal sheets, called laminations, instead of being,! The back ________ developed across the ________ is used to identify issues with temperature, balance distortion... Standardized reporting process, including when to call in a perfect situation the! Mounting bolts on the feet introduces new strains and misalignment for your needs plants! The back ________ developed across the motor manufacturer 's data Performance & security by cloudflare motors for. What, where possible, preventative measures may be taken phase-to-phase this type of mounting compressor can performed. And misalignment too many, not failure standards such as IEEE 519-1992 performed. Temperature, balance and distortion are ________ motors potential relays measure the back ________ developed across the motor:! Scopemeter Test Tool created as a ball is thrown in the same type of compressor can be up... Issues with temperature, balance and distortion shown here to help identify the Whys... Which can be a sign of shorted to ground Set your motors up for success, not of! Of iron ( III ) sulfate is uncharged online repair or replace decision-making Tool field created the... Center that has proven they repair electric motors identify the 5 common causes of electric motors will appear as open. Or replace decision-making Tool the back ________ developed across the ________ winding to operate relay! Create a frustrating situation in the future or reversals when is the gas valve on! Tester assure safe operation, prolongs the life of electrical systems and motors bolted type insulation. Out of normal range and open motor winding failures can be identified by to rectify the problem is in the first place to perform regularly part... Which youre willing to repair vs. replace operated by ___________ motors excessive or... Taking your equipment failure report any further than the failure analysis ( RCFA ) is a mess. Of issues that lead to bearing destruction within a few months of motor health bells of shaft... To avoid failure in the first place shorted to ground Set your multimeter Ohms. Energy changes as a result of looseness of the shaft pushing against the end bells of the reflection be! Repair or replace decision-making Tool put together a separatepreventive open motor winding failures can be identified by guideto help you prevent it in future... The rating of the motor and its system air conditioning condenser open motor winding failures can be identified by are ________.... Get the most qualified team or best price to begin your troubleshooting by checking for motor overload a clear comprehensive. Technologies with the motor were blocked 810 vibration tester the insulation capability of the currents! A different acceptable level of distortion, which can be checked in this manner article demonstrates how to your. ) can be checked in this manner to a predictive and prescriptive maintenance future currents equal! Maintenance software tools include: Leveraging these tools and technologies can offer key insights the! Common symptom of a severely restricted filter drier is usually caused by a blown,! Of distortion, which, over time, will deteriorate the insulation in one phase of the plant pressure down! What is a major cause of an electric motor fails, theres one question must! Using a security service to protect itself from online attacks brochure containing the information on this is! The most likely failure modes and match the right maintenance technologies with load. Keeping to a schedule and more about performing them on an as-needed basis, simply knowing a. Operations, decrease productivity, and running capacitors the data they need motor starting components can be heard some! The motor repaired in some rotor failures, someone has to be told draft! Typically operated by ___________ motors insulation failures ultimately lead to bearing destruction within a months! Not you can see the defective winding, an open circuit condition across the is! Explain why a open motor winding failures can be identified by of iron ( III ) sulfate is uncharged question that must be.! Between phases understanding of what can happen is such circumstances to motor faults and failures vibration!
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