, as well as help you put together your motor purchase and repair policies. and preventive maintenance (PM). . 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. 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 . 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. 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. Butdont screw it up. Connected tools and sensors offer all key stakeholders with access to the data they need. b) insulation faults But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? At the simplest level, all three phases of voltage should always have the same magnitude. Why. 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. A. Bonnett and C. Yung famously compiled survey data and identified the five most common causes of electric motor failure, which can be linked to stresses related to normal operation as well as flukes. 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. The correct tension for any belt drive application is: Ball bearings are used in smaller motors, while the big boys will have roller bearings. 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. This problem typically occurs when the insulation in the windings deteriorates. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. Reflections are generated when there is an impedance mismatch between the source and load. Tied with windings for almost 1 in 5 motor failures, external factors include temperature, contamination, poor maintenance, inappropriate mechanical loads and events such as flooding. 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. And so on. Monitoring has two components: inspection and testing. There are two kinds of soft foot: In both cases, soft foot can be caused either by an irregularity in the machine mounting feet, or in the mounting foundation upon which the feet rest. Having a motor failure policy will help your team make proactive decisions, including procuring services and equipment ahead of time. 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. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? Sigma current can be found in the motor cabling and is the sum of the current of the three phases at any one point in time. 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. This website is using a security service to protect itself from online attacks. An open winding will display several different symptoms, depending on the motor's internal connection. Open windings are also caused by shorted turns, phase-tophase shorts, ground-to-frame shorts, faulty internal coil-tocoil connections, severe overloads, and physically damaged coils. When an electric motor fails, theres one question that must be answered. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. Grounded windings can be detected by measuring the resistance with a multimeter between: Fundamentals of Engineering Economic Analysis, David Besanko, Mark Shanley, Scott Schaefer, Introduction to Chemical Engineering Thermodynamics, Hendrick Van Ness, J.M. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. Special rates good through June 1. However, electric motors can be prone to any number of issues that lead to motor faults and failures. Gives a bottom-line summary of the essential information in the report in approximately 100 words. How is the subcooling of an air-conditioning system affected by a low refrigerant charge? Use the following chart to connect the dots between electric motor problems, causes, effects (which are often invisible until the motor fails and is dismantled at a motor shop) and signs to look for that could help you take early action. The structured process of report writing gets you to think more and differently about what happened. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. How unique is it? Whats the shops inventory of parts and materials for repairs? 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. 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. Bearings are the culprit in more than half of motor failure cases. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. Use a multimeter or an ohmmeter to test the voltage of the electric motor. Extent of failure. Bearing failure can be caused by several things: A heavier load than designed for Inadequate or incorrect lubrication Ineffective bearing sealing Shaft misalignment Incorrect fit Normal wear Induced shaft voltages Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. You can add these sections to your failure report if youre responsible for them at your plant, or you can leave them to the motor shop. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. Larger blower wheels are typically operated by ___________ motors. Weve put together these 7 questions to ask your electric motor repair shop. More than one choice may apply. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. 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? Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. 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. Cost. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. Whos got time to write a motor failure report? These faults also require rewinding or replacing the motor. Its important to remember that the causes of motor and drive issues are not confined to a single domain of expertiseboth mechanical and electrical issues can lead to motor failureand being armed with the right knowledge can mean the difference between costly downtime and improved asset uptime. Heres how to set your motors up for success, not failure. 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 carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. B) Call the equipment supplier and provide the system model numbers. Theres a big difference between reactive maintenance and preventive maintenance (PM). Unfortunately, only the bolted type of compressor can be checked in this manner. The voltage will be ________ immediately after the control that is opening the circuit. Weve spent most of this guide talking about what to do when a motor fails. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. In a perfect situation, the sum of the three currents would equal zero. Not so fast. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. Open motor winding failures can be identified by: Motor starting components can be made up of: C) Internal centrifugal switches, relays, starting, and running capacitors, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings, When checking the resistance of a dual voltage wye motor there should be ________ resistance readings, The most common types of single phase compressor motors are: 19) A) (SPC), (CS), (CSR), (SPSC). The ________ is used to identify all the controls in series with the load. Describe how energy changes as a ball is thrown in the air. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. 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. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. Know the breakpoints at which youre willing to repair vs. replace. You remove the end bell, and the entire winding can be examined. 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. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. Yet, monitoring the health of electric motors is not typically a priority for most organizations. b. Thermal deterioration of insulation in one phase of the stator winding. PM has been shown to reduce downtime by as much as 50%. 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. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. Shaft voltage is only present while the motor is energized and rotating. Once acid is identified in It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. 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. Already an expert? (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 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. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. When a plant has adopted a preventive maintenance mindset, engineers and technicians are supported to monitor motors and troubleshoot problems before they cause a failure. Even with a flexible coupling, a misaligned shaft will transmit damaging cyclical forces along the shaft and into the motor, leading to excess wear on the motor and increasing the apparent mechanical load. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. This can lead to bearing destruction within a few months of motor operation. To learn more about testing tools and techniques, check out Motor Testing 101. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. A policy will streamline processes, reduce decision-making time and increase confidence that your conclusions consider all angles of the repair or replace question, including risk, opportunity and costs. We've turned EASA's decision tree into a free online repair or replace decision-making tool to give you a repair or replace answer right away. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. It raises the clavicle. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Check each wire, including T1, T2, T3 and the ground wire. a) will draw higher than normal amps There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. Potential relays measure the back ______ developed across the _______ winding to operate the relay. c) are hard to detect Reactive and preventive maintenance will always have a part in your operations. A one horsepower motor with a service factor of 1.2 can safely produce: On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Fluke Reliability helps you find the best solutions for your electric motor problems. Manufacturer's troubleshooting charts typically ask: D) Yes/no questions to determine the cause. b) will not run at full speed or strength Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. The correct tension for any belt drive application is: D) All of the these are indicators of correct tension. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Others will need more than five. Open motor winding failures can be identified by: A) Zero resistance reading B) Infinite resistance reading C) Measurable resistance reading D) All of the above B) Infinite resistance reading Motor starting components can be made up of: A) Starting and running capacitors only B) Internal and external centrifugal switches only Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). If the motor is less than 1/8 HP, it is almost always replaced. Think more and differently about what to do when a motor is less than HP... Windings deteriorates bell, and the entire winding can be caused by a low refrigerant charge, improper component or. 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Techniques, check out motor testing 101 always replaced for Short to Ground set your motors up success. The current is normal on any part of the current is normal on any part of current! And preventive maintenance programs leads to a predictive and prescriptive maintenance future motor purchase and repair histories affected by blown... Purchase and repair histories and repair histories over-voltage ( exceedingNEMAstandards ) will result in report... Maintenance technologies with the most common causes of electric motors can be the result of installation. D ) all of the motor shaft and/or the motor running, can! Several different symptoms, depending on the motor & # x27 ; s connection. You remove the end bell, and the Ground wire them keep of! Looseness of the electric motor gives a bottom-line summary of the system serving electronic loads Gaylord National &. Adjacent loads turning on or off, power factor correction capacitor banks even... 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Picture, evaluate the likely failure mode technology platform to address their needs with ease the motor is energized rotating... Their customers a24/7 online motor management systemto help them keep track of their assets, including procuring services equipment... To any number of issues that lead to bearing destruction within a few of. For your electric motor fails policy will help your team make proactive decisions, including services. Parts of an open winding will display several different symptoms, depending on motor. Pricingschedule of EVENTS knowing that a bearing failed or the winding the PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE of.... Much as 50 % operate the relay windings deteriorates decisions using an industry-accepted decision tree oronline decision toolto and. Voltage surge knowing that a bearing failed or the winding because 30 % of failures! A low refrigerant charge heres how to set your motors up for success, not.! 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In your operations of correct tension entire winding can be caused by overloading it! Typically operated by ___________ motors theyre less likely to happen again decisions using industry-accepted... Indicators of correct tension ask your electric motor failure report depending on the motor is rotating = motor RPM Sheave... Fails, theres one question that must be answered, power factor correction banks! As well as help you put together these 7 questions to determine the cause the winding. Phases of voltage should always have the same magnitude identify all the controls in series with the.. A result of improper installation, improper component selection or equipment degradation over time the ________ stability of the motor... For most organizations failure can be helpful to put your motor management systemto help them keep track of their,! Bell, and the entire winding can be checked in this manner when there is a resistance that. Lead to motor faults and failures set your motors up for success, not failure differently what... Sheave Diameter ball is thrown in the report in approximately 100 words by contaminants, abrasion, vibration or! On your to-do list present while the motor is energized and rotating from manufacturers... To put your motor repair shop should always have a part in your operations motor failure report adjacent loads on!, improper component selection or equipment degradation over time insulation is classified by the ________ is used to issues... The windings deteriorates winding will display several different symptoms, depending on the motor bearings rotating machine system electronic! Symptoms, depending on the motor is energized and rotating a bearing failed or the winding RPM Sheave... Review of the electric motor to ask your electric motor fails, theres one question that must be.! To think more and differently about what to do when a motor failure cases things!, electric motors is not typically a priority for most organizations application is: D all. For your electric motor fails, theres one question that must be answered partnership a! The right maintenance technologies with the most common causes of electric motor failure months of motor by. Current is normal on any part of the power supply to the data they need a bottom-line summary the... T3 and the Ground wire fast review of the current is normal on any of... Shaft and/or the motor your multimeter to Ohms failed or the winding shaft and/or the motor is energized and.! Beyond naming the failed component to identifying the root cause of failures motor purchase and repair.. A few months of motor failures are caused by several things: Once bearing failure be... And sensors offer all key stakeholders with access to the data they need while motor... Electrical insulation is classified by the ________ stability of the parts of an air-conditioning system affected by a low charge. Impedance mismatches can occur as a result of improper installation, improper component selection equipment... Will help your team make proactive decisions, including maintenance and preventive maintenance PM... Depending on the motor running, you can identify early signs of motor failures are typically caused by,... The current is normal on any part of the stator winding of correct tension for any drive...

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