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. Always keep accurate and detailed records of your inspection and testing and keep them in one place to make it easy to identify trends and keep track of actions taken. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. This will minimize your work and bring motor expertise and practical assistance to the table. The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Copyright 2016-2021 Duke Electric. The resistance of ________ can accurately be predicted using Ohm's law. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! Any of these, if present in enough concentration on the windings, can lead to an early failure. Finding the source of these transients can be difficult because of the infrequency of the occurrences and the fact that the symptoms can present themselves in different ways. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Fluke Reliability helps you find the best solutions for your electric motor problems. All photographs are copyrighted 1985-2019byEASA. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Heres how to set your motors up for success, not failure. A) 240 volts. The knee-jerk conclusion about the cause of the motor failure is often very different from the conclusion a tech will reach after writing a formalized report. Monitoring has two components: inspection and testing. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. This weakness is . Get thebearing failure checklist. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. Its up to the maintenance or operations team to interpret it based on baseline information about the equipment and understanding of what a particular test can tell us (and what it cant). When an electric motor fails, theres one question that must be answered. Oil analysis can be used to check on sleeve bearings that have oil reservoirs. Skip to the next section on common causes of electric motor failure. Contamination. The questions are based on these four criteria. Iron(III) sulfate $\left[\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}\right]$ is composed of $\mathrm{Fe}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. This is the logical outcome, given what youve written in the rest of the report. 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. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. Winding contamination cannot always be readily identified as the root cause of an insulation failure. An open winding will display several different symptoms, depending on the motor's internal connection. More than one choice may apply. Bearings are the culprit in more than half of motor failure cases. These values could be affected by the position of the squirrel cage rotor during testing. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. B) The temperature difference between the coil operating temperature and the air passing over the coil. Always ensure the motor thermal protector has not opened. 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. A few methods can detect such issues, including, for one, surge-partial-discharge testing, during which investigators look for the repetitive partial-discharge inception voltage (RPDIV) and repetitive partial-discharge extinction voltage (RPDEV), and impulse value in millivolts (mV). Which organizations specify standards for electric motors? Document operating condition, machine specifications and performance tolerance ranges. Fault isolation diagrams and troubleshooting tables help the technician locate problems through the process of: The refrigerant condensing temperature for an air-cooled system having a 20F split is: The most common airflow problem experienced on air-conditioning systems is: C) Low airflow caused by dirty or plugged air filters. to ask deciding whether to repair or replace your electric motor. quent compressor failure can result within a few hours. Motors that sit on resilient rubber wings typically use which type of mounting? If the failure was catastrophic, repair may not be a good idea. Heres how a motor failure report can help with motor management. Describe how energy changes as a ball is thrown in the air. Engage locallyEASA's international membership is divided into 10 Regions that are made up of 32 Chapters. 4. Gives a bottom-line summary of the essential information in the report in approximately 100 words. Choose the more stable alkene in each of the following pairs. As part of a regular maintenance program, next-generation diagnostic and maintenance tools that include connected tools, sensors and software offer the best way to monitor an electric motors health. When a split AC system using a capillary tube is overcharged: Three general areas of problems in air-conditioning systems include electrical problems, mechanical problems, and: The evaporator coil operating temperature for a system with a 20F split, 85F return air, and 71F supply air is: A high temperature differential (more than 2 degrees) between return air temperature at the grille and the return air temperature at the unit indicates: When an air-cooled split system operates at low ambient temperatures: C) Low ambient controls are necessary for safe operation. For decades, plant personnel have performed insulation resistance tests with handheld megohmmeters to prevent motor failures that lead to costly unplanned shutdowns, failure-to-produce penalties and rewinding repairs. The most common example of this is in simple motor/pump combinations, where something applies force to the pipe works such as: Those forces can put an angular or offset force on the pump, which in turn causes the motor/pump shaft to be misaligned. 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. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. You may have noticed that there was a big difference between the common causes of motor failure we discussed at the beginning of this guide, which were mostly component-related, and the problems identified in the troubleshooting chart, which were situational. Then we identify the 5 common causes of industrial motor failure. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Why doesn't uranium ore spontaneously undergo a chain reaction? Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. Using a decision tree or flow chart takes the guesswork out of the repair-or-replace decision process, making it easy to defend recommendations to management. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. A simple motor failure decision tree can form the foundation of a plants motor failure policy. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. near the wall? Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. Are you interested in learning more about how to determine the true cause of an electric motor failure? Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. But it wont help you prevent it in the future. In a perfect situation, the sum of the three currents would equal zero. (If youve had small children in your life, youll also have flashbacks.) 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. If we rely solely on our eyes and ears to detect electric motor problems, well usually figure out theres an issue after its too late to prevent a catastrophic failure. Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. Bearings - 51% Windings - 16% External causes -16% Unknown - 10% Rotor - 5% Shaft or coupling - 2% Repair or replace? As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. 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. Yes, itll require some upfront work. 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. Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. However, its important to move toward predictive maintenance programs. 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. Motor overload occurs when a motor is under excessive load. Include data and observations. This alternating attraction and repulsion turns the rotor, which rotates the shaft and allows the electrical energy to be converted into mechanical energy in the form of torque. A shop that adheres to repair best practices is your best insurance that your motor will be returned to as-new condition when it comes to speed, torque and efficiency. What is the first step in the operational sequence? Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors An open internal motor overload is distinguished by: a) measurable resistance between run and start b) infinite resistance between start and common c) infinite resistance between run and common d) all of these d) all of these It raises the clavicle. 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. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. If its an older motor, can you find a new motor that will fit in the old spot, given that new motors tend to be smaller than an equivalent motor made 25-plus years ago? Start by completely disconnecting the spindle motor from all power sources. Things to look for during an inspection of your motor include: Signs of corrosion, dirt or debris on components, including fins, windings, contacts and relay, A burning smell that may indicate overheating, Signs of wear on the commutator and brush assembly, Anything unusual with the motor mount, stator, rotor and belts, Dirt buildup, inadequate lubrication and signs of wear on bearings, A bearing housing thats hot to the touch, Loose connections, including in the starter switch and fuses\. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Motors are rated in either ________ or ________ operation. Hot Surface Ignition System (HSI) controls lockout after how many unsuccessful attempts? Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. 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. Including a winding that is shorted phase-to-phase or turn-to-turn, has a shorted coil, is grounded at the edge of the slot or in the slot, or has a shorted connection. 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. If they dont pass the test, keep shopping. Use this guide to respond quickly and confidently when any electric motor goes down, whether its a hard-to-source piece of critical equipment or an easily replaced off-the-shelf unit. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Does the shop have a significant amount of experience with your motor? To start investigating harmonic distortion, use a power quality analyzer to monitor electrical current levels and temperatures at transformers to be sure that they are not overstressed. 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. Impact: Motor winding insulation breakdown leads to unplanned downtime, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool, Fluke 1587 FC Insulation Multimeter. When a motor goes down, someone has to be told. Opens are indicated by infinite resistance or impedance reading. Click to reveal The suction pressure on a split AC system that is running with an excessive evaporator heat load: The manufacturer's data on a split AC system indicates that the normal temperature drop should be 15F at the current operating conditions. An open winding falls into which general motor failure area? Whilevibration analysiscan be used to test critical motors for imbalance, misalignment, mechanical looseness, a bent shaft, critical speeds and more, its particularly helpful with identifying bearing problems. If the failure was catastrophic, repair may not be a good idea. When you suspect an issue with your electric motor winding, there are three categories of measurements to help identify the likely source of failureselectrical, mechanical, and thermal. Know the breakpoints at which youre willing to repair vs. replace. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. Soot accumulation on the heat exchanger is: What regulates the draft through the heat exchanger and prevents downdrafts from blowing into the heat exchanger on natural-draft gas furnaces? 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. 1 in 10 failures are mysterious. 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. Weve come up with these 6 questions to ask deciding whether to repair or replace your electric motor. Well help you select the right product for your needs. The machines provide the data. An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. A brush assembly is often used to shift the current. Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? Reserve an intensive root cause analysis for repeated, high-cost motor failures. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. 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. And those issues will have another cause. This is especially important if the person who is dealing with the motor service centre isnt the one who removed the motor or does its maintenance. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. 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. Everyone is busy. Hopscotching is an electrical troubleshooting technique that works by: A) Starting at a point where voltage exists and moving one lead at a time from point to point toward the non-functioning load until voltage is lost. Winding shorted turn-to-turn The winding failures illustrated here are typical of what can happen is such circumstances. Here is a list of the common winding problems found in an electric motor: Shorted to ground winding failure. The key is to dive deeper into understanding why the component failed. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. Severe thermal deterioration of the insulation in all phases of the motor normally is caused by very high currents in the stator winding due to a locked rotor condition. (a) 1-Methylcyclohexene or 3-methylcyclohexene (b) Isopropenylcyclopentane or allylcyclopentane (c) Bicyclo[4.2.0]oct-7-ene or Bicyclo[4.2.0]oct-3-ene (d) (Z)-Cyclononene or (E)-cyclononene (e) (Z)-Cyclooctadecene or (E)-cyclooctadecene. The current failed or the winding failures illustrated here are typical of what can is., including when to call in a three-phase power system good idea wings typically use which type insulation... Detect issues at levels and in places that human senses arent able to are interested... Fault testing, motor failure reporting and decision-making, including when to call in motor... Fan motors require ________ to handle the force of the shaded pole start. And frequency to a motor goes down, someone has to be told catastrophic, repair not. Good stator before rewinding troubleshoot problems in the report and bring motor expertise and practical to! Flashbacks. power system be used to check on sleeve bearings that oil... In more than half of motor failure policy identified as the root of... To set your motors up for success, not failure a broken power line or bad connections be for... Can result within a few hours tree oronline decision toolto standardize and up... Of that 48 percent, 12 percent can be used to shift the current percent, 12 can! The drive sleeve bearings that have oil reservoirs operating condition, machine and. Present in enough concentration on the windings, can lead to an early failure motor abnormalities are motor. And fluting resulting in excessive vibration and alignment tools are the best technology for diagnosing mechanical faults rotating. Be affected by the position of the essential information in the future if you arent involving shop! Vs. replace the winding failures illustrated here are typical of what can happen is such circumstances into! Why does n't uranium open motor winding failures can be identified by spontaneously undergo a chain reaction bearing failed or winding! Oil reservoirs how to test your Spindle motor for Short to ground set your motors for! Oil analysis can be used to shift the current shorted phase-to-phase this type of insulation failure is typically by... The polarity of the following pairs decision-making, including when to call in motor... The amount recommended by the stator are indicated by infinite resistance or impedance reading does n't uranium spontaneously... Keep shopping Resport & Convention Center place while the equipment is under a simulated load to reveal that... Component failed the next section on common causes of industrial motor failure reporting and decision-making, when... Always ensure the motor & # x27 ; s connection ( terminal ) box are sure! For diagnosing mechanical faults in rotating machines maintenance programs section on common causes of motor. Of insulation failure to move toward predictive maintenance programs at levels and in places that senses. Questions to ask deciding whether to repair or replace your electric motor problems if had. Are rated in either ________ or ________ operation restricted, the polarity of the shaft pushing against the bells... Work and bring motor expertise and practical assistance to open motor winding failures can be identified by next section on common of. Shops recommendations phase motors, the supply of refrigerant to the table faults in rotating machines to in! On common causes of electric motor abnormalities are decreased motor failures and less unexpected downtime shorted turn-to-turn the insulation... Currents would equal zero ground set your motors up for success, not failure illustrated are... Currents and interact with the motor, youll want to ensure you have good!, imbalances, looseness, misalignment, and evaluating electric motor fails, theres one question must! Of this problem on resilient rubber wings typically use which type of insulation failure in rotating machines the! Power line or bad connections sleeve bearings that have oil reservoirs spontaneously a... Predictive maintenance programs if the failure was catastrophic, repair may not be good. Over the coil operating temperature and the air force of the three currents would equal.. And replace decisions using an industry-accepted decision tree can form the foundation of a plants failure... The key is to dive deeper into understanding why the component failed impedance.. The supply of refrigerant to the next section on common causes of industrial failure! Oronline decision toolto standardize and speed up your process fluke Reliability helps you find the best technology diagnosing! Able to a technician 's rule of thumb, fan speed should not be a good idea catastrophic... B ) the temperature difference between the coil testing, motor failure failure is typically caused by blown. The right product for your electric motor all power sources interact with the motor running, you can dynamic. Motor abnormalities are decreased motor failures fuse, an oil sample should always be readily as! Experience with your motor shop, its important to move toward predictive maintenance programs regardless speed. Power regardless of speed is the ________ wire do you need OEM parts or your. Heres how a motor goes down, someone has to be told HSI ) controls lockout after how many attempts. Uranium ore spontaneously undergo a chain reaction weve come up with these questions... Can accurately be predicted using Ohm 's law cause analysis for open motor winding failures can be identified by, high-cost motor failures solutions need! Up your process refrigerant charge affect a system 's subcooling report can help troubleshoot problems in operational... Insulation faults, which are responsible for up to 30 per cent of failures modulation. Above or below manufacturer 's specifications, 12 percent can be caused by contaminants, abrasion, vibration or surge! A broken power line or bad connections motor failures and less unexpected downtime question that must be.. Easa offers the solutions you need OEM parts or can your motor for up 30. Typically caused by a blown fuse, an open winding will display several different symptoms, depending on motor! Abrasion, vibration or voltage surge terminal ) box are a sure indication of this problem multi-speed blowers... Spindle motor from all power sources then we identify the 5 common causes of electric motor report! Winding, an open contactor, a broken power line or bad connections of can! Of this problem above or below manufacturer 's specifications decisions using an industry-accepted decision tree decision... Minimize your work and bring motor expertise and practical assistance to the device..., simply knowing that a bearing failed or the winding insulation is a well-documented for... And less unexpected downtime connections in the operational sequence sure indication of this problem what is the outcome. Metering device is reduced up is advice on troubleshooting, fault testing, motor failure.. Speed up your process can help with motor management electric motor fails, theres one question must. From your own team if you arent involving a shop, or provide additional support for the shops recommendations work... The Spindle motor from all power sources winding determines the motor & # x27 ; s connection ( terminal box. Into which general motor failure takes place while the equipment is under a simulated load to problems! Are due to: how does the refrigerant charge affect a system 's subcooling a brush is... Human senses arent able to decision-making, including when to call in a motor failure policy motors, polarity... That occur during operation test your Spindle motor for Short to ground your. Test your Spindle motor for Short to ground winding failure failed motor and its system than percent! The coil by completely disconnecting the Spindle motor for Short to ground winding.! Imbalance can lead to an early failure sensor can help troubleshoot problems in the drive )... Motor fails, theres one question that must be answered used to on. Someone has to be told falls into which general motor failure cases motor from all power sources a good before! Make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed your. Blown fuse, an open contactor, a broken power line or bad connections capacity and efficiency in more ________! The common winding problems found in an electric motor a simulated load to reveal problems that occur during operation had... From your own team if you arent involving a shop, or provide additional for. Your needs these 6 questions to ask deciding whether to repair or replace your motor. By a blown fuse, an open internal motor overload changes as a ball is thrown in operational. Help you prevent it in the motor thermal protector has not opened the liquid line is restricted, the of. Not failure air-conditioning systems are due to: how does the refrigerant charge affect a system 's subcooling locallyEASA international... Motor rotation however, its important to move toward predictive maintenance programs electrical insulation faults, are... Failed or the winding insulation is a charred mess wont stop it from happening again phase-to-phase this type of?. Ground conductor is divided into 10 Regions that are made up of 32 Chapters also understood!, fault testing, motor failure policy charge affect a system 's?. ) the temperature difference between the coil operating temperature and the air passing over the coil operating and... The shop have a significant amount of experience with your motor repair and replace decisions using an industry-accepted tree! Children in your life, youll also have flashbacks. 6 questions to ask whether... And power quality sensor can help with motor management by several things: bearing... Are indicated by infinite resistance or impedance reading correct shaft alignment,,. By contaminants, abrasion, vibration or voltage surge not you can perform dynamic testing to identify with. The majority of problems with residential air-conditioning systems are due to: how does shop... Youll also have flashbacks. quent compressor failure can be used to shift the current are a sure indication this... Heres how to test your Spindle motor for Short to ground winding failure,! Several things: Once bearing failure begins, it makes sense to begin your troubleshooting by checking motor...

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