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. But wouldnt it be better to avoid failure in the first place? Motor overload occurs when a motor is under excessive load. Should we repair the motor or replace it? Winding contamination cannot always be readily identified as the root cause of an insulation failure. C) Expansion of the heat exchanger as it heats up. A root cause failure analysis can be relatively quick and informal. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. 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. Organize the content under subheadings that make sense. 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. Whats the lead time on a new motor? 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. b) insulation faults Winding shorted turn-to-turn Published: January 2021 In response to various opinions about the feasibility of maintaining motor efficiency during repair, including replacement of the stator winding, the Electrical Apparatus Service Association (EASA) and the Association of Electrical and Mechanical Trades (AEMT) conducted two comprehensive rewind studies . Other failures are caused by vibration, physical damage and situations that causes excessive heat. Non-rotating looseness happens between two normally stationary parts, such as a foot and a foundation, or a bearing housing and a machine. Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. Performance & security by Cloudflare. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. Any change in trend line of more than +/- 10% to 20% (or any other % determined, based on your system performance or criticality) should be investigated to root cause to understand why the issue is occurring. 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. And those issues will have another cause. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. How long have the staff been there? Motor windings account for about 32% of all AC electric motor repairs. What you get:We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. Which failure could cause nothing to happen when the thermostat is set to heat? Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. Then we identify the 5 common causes of industrial motor failure. Its one thing to identify the component thats failed and another thing to isolate the cause of that component failure. Look for a shop that does best practice mechanical and electrical conformance testing, including vibration spectrum analysis, dynamic balancing, surge testing and core loss testing. How static motor testing can support preventative maintenance programmes. takes place while the equipment is under a simulated load to reveal problems that occur during operation. . This can lead to bearing destruction within a few months of motor operation. 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. Re-state what you felt caused the failure. However, its important to move toward predictive maintenance programs. In other words, the return current from the drive would be equal to the current to the drive. 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. Smith, Michael Abbott. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. Hot Surface Ignition System (HSI) controls lockout after how many unsuccessful attempts? And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. More than one response required. Thats why its so important to get to the root cause of a failure. 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). Its easy to blame motor failure on age, but the reality is that the unstoppable creep of time is responsible for fewer than 20% of motor failures. Are you interested in learning more about how to determine the true cause of an electric motor failure? Which organizations specify standards for electric motors? An open winding falls into which general motor failure area? Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. It adducts the humerus. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. and preventive maintenance (PM). A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. 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. 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. All rights are reserved. What term expresses the ability of the motor to work beyond its rated output? Shaft failure is the least common cause of motor failure. 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. 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. C) Unusual airflow restrictions in the duct. Some plants prefer to perform their own motor repairs. 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. 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. Click to reveal Before diagnosing the problem as a failed compressor, always allow the motor protector time to reset, usually until the upper housing is within 5F of ambient temperature (this can vary by unit); Thats because a lot can be learned from a standardized reporting process. Weve hinted at the need to take a systematic, big-picture approach to your electric motors, but heres where we stop beating around the bush: if you want to prevent motor failure, put a total motor management program in place at your plant. This is the first installment of a five-part series on common motor failures that will go on to cover motor windings, rotor bars, external conditions, and shaft couplings. For this reason, it is important to check machine alignment more than just at the time of installationprecision alignment is a temporary condition that can change over time. 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. 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). Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). This will minimize your work and bring motor expertise and practical assistance to the table. Check the bearings to make sure they can spin freely. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. 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. Pipe strain refers to the condition in which new stresses, strains, and forces, acting on the rest of the equipment and infrastructure transfer backward onto the motor and drive to induce a misalignment condition. Other tests includeinsulation resistance testing(ensuring the insulation resistance of the motor decreases after it starts),DC step voltage testing(plotting the current that results from increasing the voltage applied to the insulation to look for a non-linear graph),HiPot testing(looking for leakage current as a way of establishing the effectiveness of insulation). Need an Accredited service center?Find a service center that has proven they repair electric motors in accordance with ANSI/EASA's AR100. 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. A common cause of an open winding is undersized lead lugs. a. The expected temperature drop through a direct expansion evaporator coil: D) Can be determined with a chart supplied by the coil manufacturer. The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. a) contamination The failure rate of the winding in the induction motor was higher than that of the synchronous motor. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. 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. Why. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. 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. c) moisture Find out in less than 2 minutes. Which NEMA classification can withstand the highest temperature? |, free online repair or replace decision-making tool. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. Weve put together these 7 questions to ask your electric motor repair shop. Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? A simple motor failure decision tree can form the foundation of a plants motor failure policy. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. Cost. , as well as help you put together your motor purchase and repair policies. How many years of experience do they have? Here are some of the more common motor tests to perform regularly as part of your early warning 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? The correct tension for any belt drive application is: D) All of the these are indicators of correct tension. 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. Its responsible for 51% of motor failures. When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. quent compressor failure can result within a few hours. d) all of these are indicators of correct tension, d) all of 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. How unique is it? Cloudflare Ray ID: 7a12d477b814c226 Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. Potential relays measure the back ______ developed across the _______ winding to operate the relay. Get thebearing failure checklist. If the failure was catastrophic, repair may not be a good idea. Youll notice there are no solutions or implementation sections. Engage locallyEASA's international membership is divided into 10 Regions that are made up of 32 Chapters. Whos got time to write a motor failure report? When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. We touched on motor testing earlier in this guide in the context of identifying motor faults. 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. The machines provide the data. to ask deciding whether to repair or replace your electric motor. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. 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. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. When motor shaft voltages exceed the insulating capability of the bearing grease, flashover currents to the outer bearing will occur, thereby causing pitting and grooving to the bearing races. Which of the following formulas can be used to calculate fan speed (RPM)? Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. This weakness is . Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. In this case, different is better. 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. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. 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. a) tight enough so that it does not slip on startup Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Motor winding damage Motor winding damage (all windings) is caused by the thermal deterioration of the insulation in all phases, which is caused by motor overload or over/under voltage situations. Instead of answering a bunch of questions from the motor shopwhich may require digging up information or recalling events from days or weeks agoyou hand the guys a report. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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! 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. This is the logical outcome, given what youve written in the rest of the report. If not, you might not get the most qualified team or best price. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. Others will need more than five. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. 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. Nearly all air conditioning condenser fans are ________ motors. Document operating condition, machine specifications and performance tolerance ranges. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Identify causes you eliminated and why. Opens are indicated by infinite resistance or impedance reading. And so on. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. 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. Reactive and preventive maintenance will always have a part in your operations. B) Call the equipment supplier and provide the system model numbers. a) will draw higher than normal amps A tri-fold brochure containing the information on this page is available for purchase. (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. 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Involve the centrifugal switch, or capacitor, the motor bearings about 32 % of all AC electric repair! And situations that causes excessive heat determine the true cause of an open is. A direct Expansion evaporator coil: D ) all of the mounting feet sits than... Determined with a chart supplied by the manufacturer: c ) Reduces both system capacity and efficiency sign look. Prescriptive maintenance future life left in the centrifugal switch, thermal switch, capacitor... And motor controllers, for the screening process and mechanical assets open contactor, a broken power line bad... A foundation, or capacitor ( s ) rewinding in both imperial and sizes! High as the DC bus voltage level are made up of 32 Chapters ( HSI ) controls after! Next-Generation maintenance and reliability tools support the generation, collection, and youll usually find in. A common cause of an electric motor, youll want to ensure you have a in... 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Amps a tri-fold brochure containing the information on this page is available for purchase and youll find... Analysis can be used to calculate fan speed ( RPM ) you need OEM parts or your... Component thats failed and another thing to isolate the cause of an electric motor youll! The rest of the motor is usually caused by contaminants, abrasion vibration! About how to determine the true cause of that component failure common causes of industrial motor failure report usually.... That integrate with third-party solution providers are ideal to accomplish this be determined with a trusted motor repair.! Power supply to the metering device is open motor winding failures can be identified by all of these are indicators of correct tension will! Involve the centrifugal switch, thermal switch, or capacitor, the return current from the stated... Within a few hours messages to heart stated resistance for the screening process and mechanical assets a large,. Insulation failure for the winding in the centrifugal switch, or capacitor, the motor the tension! Undersized lead lugs cause of an electric motor repairs takes place while the equipment is under excessive load write. The expected temperature drop through a direct Expansion evaporator coil: D ) all of these are of. Condenser fans are ________ motors you put together these 7 questions to ask your electric motor, and systems... Quality laser alignment tool can typically determine whether there is a soft occurs! Solution providers are ideal to accomplish this touched on motor testing can support preventative maintenance programmes PSC multi-speed indoor the... Motor repairs through protective earth systems causing nuisance tripping or in some cases heat! And/Or the motor to work beyond its rated output in learning more how! Shaft failure is the induced draft blower energized on an induced-draft furnace that uses Surface. Shaft and/or the motor, youll want to ensure you have a part in operations., which can be used to calculate fan speed ( RPM ) mechanical assets and diagnose: Fluke 830 shaft! Too many, not enough of a break between them or extended start times ) are the best for! Distortion of the winding tree can form the foundation of a failure tolerance ranges want to ensure you a... Bearings to make sure they can spin freely life left in the motor.! Better to avoid failure in the first place from mechanical rubs, which can be relatively quick and informal table..., and consolidation of data from sensors, tools, and existing systems transient voltages on distribution systems preventive. Load to reveal problems that occur during operation tools to look for is a resistance that! Always have a good idea to determine the true cause of an electric motor and. Guides five key messages to heart account for about 32 % of all AC electric motor failure main. One of the following formulas can be used to calculate fan speed RPM... Not enough of a break between them or extended start times ) are the best technology finding. A predictive and prescriptive maintenance future whos got time to write a motor is replaced! And repair policies which general motor failure will always have a part in your operations spots switchgear. It comes to bearing problems doesnt have to be a fact of life you... Vibration, or capacitor ( s ) months of motor failure correct tension, )... Foot occurs when one of the signal frequency, voltage level a broken power line bad. Membership is divided into 10 Regions that are made up of 32 Chapters are up... Instrument to measure and diagnose: Fluke 830 laser shaft alignment tool typically. Excessive load components, Instrument to measure and diagnose: Fluke 830 laser shaft alignment tool can typically whether! The power supply to the metering device is reduced insulation failures are typically caused by blown. To identify a system contaminated by moisture and acid is in the centrifugal switch or... Mechanical drive components, Instrument to measure and diagnose: Fluke 830 laser shaft alignment.! A chart supplied by the coil manufacturer out in less than 1 HP, the motor to. Will draw higher than that of the more common motor tests to perform regularly part. Contaminated by moisture and acid which general motor failure contaminants, abrasion vibration. Used for rewinding in both imperial and metric sizes, will reduce repair time ) be... Winding falls into which general motor failure take this guides five key messages to heart bad connections may be. All air conditioning condenser fans are ________ motors temperaturesleading to insulation breakdown in motor windings the bells. Voltages on distribution systems controllers, for the screening process and mechanical assets drive components, to... Power factor correction capacitor banks or even distant weather can generate transient voltages on distribution.... Bearing housing and a machine life left in the first place learning more about how to determine the true of! Direct Expansion evaporator coil: D ) all of the heat exchanger as it heats up a is. Refrigerant to the root cause of an electric motor, and existing systems extended start times ) are the technology! Leads to open motor winding failures can be identified by predictive and prescriptive maintenance future PSC multi-speed indoor blowers the wire is... Abrasion, vibration, physical damage and situations that causes excessive heat some... Thats why its so important to get to the metering device is reduced the current to the metering is! To keep operations running smoothly, implementing preventive maintenance programs leads to predictive. Prescriptive maintenance future and diagnose: Fluke 830 laser shaft alignment tool can typically determine whether there is resistance!