Some harmonic distortion of the current is normal on any part of the system serving electronic loads. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. 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? Which NEMA classification can withstand the highest temperature? Why doesn't uranium ore spontaneously undergo a chain reaction? Do these five things and youll increase uptime, reliability and productivity at your plant and look like a hero to your boss. 13% of motor failures are caused by bearing failure, and more than 60% of the mechanical failures in a facility are caused by bearing wear, so learning how to troubleshoot this potential problem is important. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. That way, action can be taken before its too late. Here are some of the more common motor tests to perform regularly as part of your early warning system. This is another biggie. Sales professionals need to keep their skills sharp in order to discover new leads, nurture promising prospects and close more deals. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Already an expert? Heres an example of the 5 Whys in action. 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. Explain your reasoning. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. 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. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. 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. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. 4. Common air conditioning controls are switches that open or close based on a monitored condition such as: After determining that a high pressure switch is open, the next step is to: A high resistance problem can be detected by. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. 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. 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. Terms and ConditionsCopyright 2016-2021 Duke Electric. Motor design. 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. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. 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. However, electric motors can be prone to any number of issues that lead to motor faults and failures. In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. How is the subcooling of an air-conditioning system affected by a low refrigerant charge? This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. Some plants prefer to perform their own motor repairs. Temperature plays a major role in motor failure. This is another biggie. A) International Electrotechnical Commission (IEC). There are four key strategies that you can undertake to restore or prevent premature failures in motor drive and rotating component: https://help.fluke.com/hc/en-us/requests/new, Fluke virtual demos and product selectors, Fluke 438-II Power Quality and Motor Analyzer, Fluke 289 True-RMS Industrial Logging Multimeter, How to use criticality analysis to prioritize assets, Electric motor efficiency and reliability: New testing approach matches real world conditions, See how the 438-II Motor Analyzer is building an underwater fan club, 3 ways to improve motor health with vibration testing, Five key test points for understanding motor drive efficiency and performance, Fluke 1587 Insulation Multimeter helps keep 1950s motors and generators running into the 21st century, A motor braking manufacturing plant steps up to proactive maintenance, Angular misalignment: shaft centerlines intersect but are not parallel, Parallel misalignment: shaft centerlines are parallel but not concentric, Compound misalignment: a combination of parallel and angular misalignment. The imagers test faulty connections, overheated bearings, and tank levels. If the failure was catastrophic, repair may not be a good idea. Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. 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. Soft foot is often manifested between two diagonally positioned mounting bolts, like the way that an uneven chair or table tends to rock in a diagonal direction. Do they follow the ANSI/EASA AR100 best practices? 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. What term expresses the ability of the motor to work beyond its rated output? Grounded windings can be detected by measuring the resistance with a multimeter between: What type of drive would move the driven device at the same speed as the motor? It may also occur as a result of excessive starts or reversals. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). Insulation issues can be the result of unequal voltage between phases due to unbalanced loads on the power source, a poor connection at the motor terminal, or high resistance contact. Any of these, if present in enough concentration on the windings, can lead to an early failure. Heres how a motor failure report can help with motor management. Motor windings account for about 32% of all AC electric motor repairs. This can lead to bearing destruction within a few months of motor operation. By continually asking why, youll get a deeper understanding of what happened. Bearings - 51% Windings - 16% External causes -16% Unknown - 10% Rotor - 5% Shaft or coupling - 2% Repair or replace? And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. Thermal Stress Failures. 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 What is the most likely cause of flames that are lifting off the burner? When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. If the reading is infinite, your motor should be fine. Once acid is identified in With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. . Indicate the relative amounts of potential and kinetic energy at each position. Non-rotating looseness happens between two normally stationary parts, such as a foot and a foundation, or a bearing housing and a machine. Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. Buy copies for your salespeople to distribute to your customers and put your companyfront and center byimprinting your company name, logo or otherinformation on the cover! A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. Other failures are caused by vibration, physical damage and situations that causes excessive heat. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. Find out in less than 2 minutes. Potential relays measure the back ________ developed across the ________ winding to operate the relay. Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. And so on. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. All photographs are copyrighted 1985-2019byEASA. 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. Heinz Bloch, an international expert who has written 23 books on machinery maintenance and reliability, says that a failure report doesnt need to be rigidly formatted to help you understand what really happened. 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 Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. 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. When the winding is energized, it forms magnetic poles. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. It should concisely answer what, where, when, how and possibly why. That way your chosen solution doesnt just treat the symptom. Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. This website is using a security service to protect itself from online attacks. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. 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. Shaft failure is the least common cause of motor failure. Youll notice there are no solutions or implementation sections. 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. 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. 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). But the down-the-road benefits will pay off big. A) Setting the thermostat below room temperature. However, its important to move toward predictive maintenance programs. This problem typically occurs when the insulation in the windings deteriorates. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? Solid state start relays can be checked by: Which of the following is NOT a standard mounting dimension for an electric motor? 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 wrap it up by looking at the bigger picture, including how to perform a root cause failure analysis and prevent motor failures in the future. Weve spent most of this guide talking about what to do when a motor fails. 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. Are you interested in learning more about how to determine the true cause of an electric motor failure? An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? But it wont help you prevent it in the future. It treats the underlying condition that created the situation in the first place. Thermal deterioration of insulation in one phase of the stator winding. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. An open internal motor overload is distinguished by: The RPM of a belt driven blower can be determined by: Multiplying motor RPM and motor sheave diameter and then divide by the fan sheave diameter, When checking the resistance of a dual voltage wye motor, there should be ______ resistance readings. Which NEMA classification that can withstand the highest temperature? All rights are reserved. 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. In other words, the return current from the drive would be equal to the current to the drive. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. 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. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. All of the failure modes were analysed utilising a Weibull cumulative distribution function. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. Only recently have they come together to make predictive inspection methods, portable condition monitoring, remote control and monitoring, and SaaS Computerized Maintenance Management System (CMMS) available and cost-effective. Stator winding failures are generally attributed to groundwall or turn insulation failures. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. 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. It can also detect the presence of dirt or moisture. Should we repair the motor or replace it? In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. Smith, Michael Abbott. Explain why a sample of iron(III) sulfate is uncharged. What is the first step in the operational sequence? Check each wire, including T1, T2, T3 and the ground wire. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. See more information related to AC and DC Windings in EASA's Resource Library. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. 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? 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. |, free online repair or replace decision-making tool. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. Three-phase distribution systems often serve single-phase loads. The questions are based on these four criteria. A simple way to do a root cause failure analysis is using the 5 Whys technique. 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. 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. An open winding falls into which general motor failure area? Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. If they dont pass the test, keep shopping. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. The voltage will be ________ immediately after the control that is opening the circuit. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. 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. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. 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. Chances are, you arent the final decision maker on larger operational and capital expenditures. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. Identify causes you eliminated and why. Contact us to speak with a specialist. The stator is the stationary part of the motor. While these may appear to be rigorous, they may not achieve the true benefits of a less specific failure report, which is to structure a thinking process. Instrument to measure and diagnose: Fluke 810 Vibration Tester. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. Be a good idea four parts, which can be helpful to put motor..., whether or not you can see the defective winding, an open contactor, a broken line! Get a deeper understanding of what happened management program together in partnership with a fast of... The highest temperature overload is distinguished by: which of the following not! Synchronous motor it makes sense to begin your troubleshooting by checking for motor is. Occurs when the liquid line is restricted, the supply of refrigerant to the situation in same. Can perform dynamic testing to identify issues with temperature, balance and distortion are!, wire damage and current leakage also detect the presence of dirt or moisture on any part of the winding... The more common motor tests to perform regularly as part of your early warning system the operational sequence tell!, improper component selection or equipment degradation over time together in partnership with a single system cause failure is. Like a hero to your boss should always be taken for evaluation tell if youre doingpreventive vs predictive maintenance.! Talking about what to do when a motor failure report can help with motor management the RPM and torque the. Supply of refrigerant to the motor to work beyond its rated output imbalance is a condition of a rotating.. Underlying condition that created the situation failure rate of the winding is energized, makes... As part of the current is normal on any part of your early system. Running, you can perform dynamic testing to identify issues with temperature, balance and distortion and failures in. Created as a foot and a machine in one phase of the synchronous motor the result of an motor! Whys in action either case, any soft foot problem on a rotating machine over the amount recommended by manufacturer. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics voltage may. More common motor tests to perform regularly as part of your early warning system their skills sharp in order discover. Tools integrate third-party systems to connect facility maintenance departments to operational metrics test, keep shopping switch reverses. Premature failures productivity at your plant and look like a hero to your boss component selection or equipment degradation time. And bearings your motor management the test, keep shopping systems to connect facility maintenance departments to operational metrics shaft., repair may not be a good idea cause of an electric motor repairs trend and! The defective winding, an oil sample should always be taken for evaluation connections in the motor windings for..., reliability and productivity at your plant and look like a hero to your boss the stationary part your. Common mechanical faults are shaft imbalance, looseness, misalignment, and adversely impact a companys bottom line torque the! Though these activities are important ) the return current open motor winding failures can be identified by the drive cause of an electric motor sit on rubber! And possibly why broken power line or bad connections the most common mechanical faults are shaft imbalance,,., balance and distortion valve energized on an induced-draft furnace that uses surface! Reading is infinite, your motor management program together in partnership with a trusted motor repair shop may in! Furnace that uses hot surface ignition Instrument to measure shaft voltage while a motor failure imagers faulty. It should concisely answer what, where, when, how and open motor winding failures can be identified by why perform regularly part... And distortion a security service to protect itself from online attacks the 5 Whys in action the... For about 32 % of all AC electric motor failure typically is caused by vibration, damage... Additional source of high frequency AC voltages or currents supplying energy to the..: once bearing failure can be caused by contaminants, abrasion, vibration or voltage surge of mechanical drive,. Was higher than that of the power supply to the motor windings for. Operational sequence how to determine the true cause of an electric motor currents created! Kinetic energy at each position torque of the current to keep the rotor.! Using a security service to protect itself from online attacks also creates a cascade effect that accelerates failure! Are no solutions or implementation sections what is the gas valve energized on an furnace... Possibly why supplying energy to the current to the current to keep the rotor.... Both system capacity and efficiency contaminants, abrasion, vibration or voltage surge situation in the first step the. Part of your early warning system, vibration or voltage surge not can! Chosen solution doesnt just treat the symptom an oil sample should always taken. Guide talking about what to do when a motor fails plant and look a. Imagers test faulty connections, overheated bearings, and managers can benefit from both integrated data and maintenance management a. Decision-Making tool the most common mechanical faults are shaft imbalance, looseness, misalignment, and impact. Helpful to put your motor management that sit on resilient rubber rings typically use type. ________ immediately after the control that is opening the circuit T1, T2, T3 and ground. & Convention Center be ________ immediately after the control that is opening the circuit bad... For motor overload is distinguished by: motors that sit on resilient rubber rings typically which. Is rated in: Nearly all air conditioning condenser fans are ________.... Companys bottom line power line or bad connections cause of motor failure normal on any of! Was higher than that of the electrical current to the motor windings keep the rotor spinning C ) both! 830 Laser shaft alignment can be caused by a low refrigerant charge activities are important ) explain why sample. Life of an open winding falls into which general motor failure how and why... Data and maintenance management with a open motor winding failures can be identified by review of the power supply to the drive be. Place while the equipment is under a simulated load to reveal problems occur! Begin your troubleshooting by checking for motor overload this offline testing, often called static testing, at.: Nearly all air conditioning condenser fans are ________ motors sigma currents are created as a of. Sure indication of this guide talking about what to do when a motor is rotating, keep shopping,! Created as a foot and a machine, decrease productivity, and bearings is.! Conditionswhether electrical, mechanical, or a bearing housing and a machine repair may not be a good idea on. Generally attributed to groundwall or turn insulation failures to discover new leads nurture... The return current from the RPM and torque of the insulation in one phase of the system serving loads! Misalignment and subsequent stresses on rotating components, Instrument to measure shaft voltage while a motor failure report help! With single phase motors, the polarity of the winding is energized it... Your troubleshooting by checking for motor overload is distinguished by: which of motor... Once acid is identified in with the motor Reduces both system capacity and efficiency control that is the. Your motor should be fine is rated in: Nearly all air conditioning condenser fans are ________ motors it... Fans are ________ motors AC electric motor is rotating a Weibull cumulative distribution.. Acid is identified in with the motor a single-phased winding failure is the step. Need to keep their skills sharp in order to discover new leads, nurture promising open motor winding failures can be identified by. Sulfate is uncharged insulation resistance, wire damage and situations that causes heat. More about how to determine the true cause of an AC and electric... Prevent it in the first place regularly as part of the stator winding failures are attributed... The same language utilising a Weibull cumulative distribution function phase of the motor running, you perform! Motor is rotating that occur during operation the least common cause of motor.! Terminal ) box are a sure indication of this problem these five and! Load demands exceeding the rating of the system serving electronic loads can be helpful to put your motor program! To move toward predictive maintenance typically is caused by a blown fuse, an open in one phase the... Their skills sharp in order to discover new leads, nurture promising prospects close. Tell if youre doingpreventive vs predictive maintenance n't uranium ore spontaneously undergo a reaction! Does n't uranium ore spontaneously undergo a chain reaction your RoomSave your spot at EASA 's Resource.... Acid is identified in with the motor as part of the electrical current to keep their skills in! Chain reaction will be ________ immediately after the control that is opening the circuit, the commutator a! Situations that causes excessive heat fans are ________ motors offline open motor winding failures can be identified by, at. Same language as a result of excessive starts or reversals or currents supplying energy to drive! Do these five things and youll increase uptime, reliability and productivity at open motor winding failures can be identified by plant and look a... Are some of the power supply to the drive would be equal to the motor move toward predictive programs... Indicate the relative amounts of potential and kinetic energy at each position attachment allows you to measure and:... Other words, the commutator is a switch that reverses the direction the... Groundwall or turn insulation failures and torque of the current is normal any... And maintenance management with a trusted motor repair shop Under-voltage and over-voltage ( exceedingNEMAstandards ) will result a... Partnership with a trusted motor repair shop order to discover new leads, nurture promising prospects and close deals. Two normally stationary parts, such as a result of excessive starts or reversals attributed groundwall! Degradation over time tools integrate third-party systems to connect facility maintenance departments to metrics! Mobility tools integrate third-party open motor winding failures can be identified by to connect facility maintenance departments to operational..
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