open motor winding failures can be identified bywendy williams sister lawyer

A single-phased winding failure is the result of an open in one phase of the power supply to the motor. 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. Youll notice there are no solutions or implementation sections. A megohmmeter can detect: In this case, different is better. Everyone is busy. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. Organize the content under subheadings that make sense. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. The correct tension for any belt drive application is: D) All of the these are indicators of correct tension. Use a multimeter or an ohmmeter to test the voltage of the electric motor. What causes electric motors to fail? 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. 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. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. If not, you might not get the most qualified team or best price. It can also detect the presence of dirt or moisture. 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. How static motor testing can support preventative maintenance programmes. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Some harmonic distortion of the current is normal on any part of the system serving electronic loads. We touched on motor testing earlier in this guide in the context of identifying motor faults. 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. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. Smith, Michael Abbott. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. Yet determining the cause is a critical step in protecting your motors. Check each wire, including T1, T2, T3 and the ground wire. Keep all of your organizations assets up and running without downtime. 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. D) The large temperature drop indicates the airflow is less than required. The structured process of report writing gets you to think more and differently about what happened. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. But it wont help you prevent it in the future. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. Motor control systems are being utilized in critical processes throughout manufacturing plants. We can see your eyes rolling. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. 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. A) Setting the thermostat below room temperature. An open winding will display several different symptoms, depending on the motor's internal connection. 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. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. Contact us to speak with a specialist. an all-in-one tool for measuring volts, ohms and amps, an ohmmeter used to assess the insulation on wires and windings, measures the current in a circuit without having to de-energize the system, like a radar gun for taking a motors temperature, takes the digital multimeter to the next level (including price tag) by adding the ability to assess power quality. 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. What is the first step in the operational sequence? Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. The correct tension for any belt drive application is: A simple motor failure decision tree can form the foundation of a plants motor failure policy. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. 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 For example, a transient may appear on control cables that dont necessarily cause equipment damage directly but may disrupt operations. Other failures are caused by vibration, physical damage and situations that causes excessive heat. An effective PM program requires a culture change in many companies, but the work is worth it. Find out in less than 2 minutes. How unique is it? Will the shop do the work themselves, or will they outsource it? Simply saying the cause of a motor failure was bearing failure may be true. 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. Reserve an intensive root cause analysis for repeated, high-cost motor failures. b) will not run at full speed or strength However, these tests only provide a "snapshot" of motor health. Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. Then we identify the 5 common causes of industrial motor failure. 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. Once acid is identified in takes place while the equipment is under a simulated load to reveal problems that occur during operation. 4. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Why. Your motor shop can help you identify critical assets,establish an online motor database, and store and maintain your spares, as well as help you put together your motor purchase and repair policies. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. Know the breakpoints at which youre willing to repair vs. replace. 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. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. 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. 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. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. 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. (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. 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. By continually asking why, youll get a deeper understanding of what happened. The key is to dive deeper into understanding why the component failed. If there is no resistance or the resistance is uneven, the motor is likely faulty. 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? Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. Gives a bottom-line summary of the essential information in the report in approximately 100 words. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. What causes the little pops and ticking that can be heard in some furnaces before the blower comes on? 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. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Heres an example of the 5 Whys in action. This website is using a security service to protect itself from online attacks. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. You can email the site owner to let them know you were blocked. At the simplest level, all three phases of voltage should always have the same magnitude. Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. Nearly all air conditioning condenser fans are ________ motors. An open winding falls into which general motor failure area? Stator winding failures are generally attributed to groundwall or turn insulation failures. The machines provide the data. 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. 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). A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. 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. If they can't, lubricate them. 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. 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. Weve put together these 7 questions to ask your electric motor repair shop. Sigma currents are essentially stray currents that circulate in a system. Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. EASA's new streaming sales videos provide relevant and insightful training. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. Consider the size, age, type and application of your motor. Reproduction of these photographs by print or electronic means is prohibited. Temperature plays a major role in motor failure. The way the information is communicated plays an important role in the way the situation is handled and decisions that are made, both for the motor in question and the entire fleet. Theres a big difference between reactive maintenance and preventive maintenance (PM). 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! 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. 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. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. When a motor goes down, someone has to be told. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Winding shorted turn-to-turn How long have the staff been there? Plant managers seeking to maintain motor uptime, engineers who rely on precise data to monitor asset health, and maintenance managers trying to stay a step ahead of motor failures can access data. 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. Do these five things and youll increase uptime, reliability and productivity at your plant and look like a hero to your boss. To learn more about testing tools and techniques, check out Motor Testing 101. Butdont screw it up. Motor windings account for about 32% of all AC electric motor repairs. You remove the end bell, and the entire winding can be examined. 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. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. How efficient is the motor that failed? Its responsible for 51% of motor failures. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). 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. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. 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. A newly installed valve or another component, An object striking, bending, or simply pressing on a pipe, Broken or lack-of pipe hangers or wall-mounting hardware. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. If the failure was catastrophic, repair may not be a good idea. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. That way you can save your bearing next time, instead of simply having it fail again. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. Excessive motor heat is a major cause of motor failure. Cost. Include data and observations. Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. Bearing failure is an expensive problem both in terms of motor repair and downtime, so helping to prevent this by measuring shaft voltage and bearing current is an important diagnostic step. 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. If the failure was catastrophic, repair may not be a good idea. 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 . Its one thing to identify the component thats failed and another thing to isolate the cause of that component failure. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? Sounds simple. Instead, rely on the U.S. Department of Energy, whose Service Center Evaluation Guide opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". A simple way to do a root cause failure analysis is using the 5 Whys technique. Rotating looseness is caused by excessive clearance between rotating and stationary elements of the machine, such as in a bearing. Explain your reasoning. A) Adding refrigerant increases the system subcooling. Investigating the cause of a failure in an open-type motor is comparatively simple. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Start by completely disconnecting the spindle motor from all power sources. A root cause failure analysis can be relatively quick and informal. Contamination. To help mitigate these failures, a variety of motor tests can be performed on electric motors. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. 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. And so on. Ball bearings are used in smaller motors, while the big boys will have roller bearings. Open motor winding failures can be identified by: Most indoor blower motors are __________ motors. PM has been shown to reduce downtime by as much as 50%. (Here are7 ways to screw up vibration analysis.). C) Expansion of the heat exchanger as it heats up. Reflections are generated when there is an impedance mismatch between the source and load. This weakness is . c) 1/64th inch deflection per 1 inch span between drive shaft and driven shaft Weve put together a separatepreventive maintenance guideto help you out. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. c) moisture 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. Should we repair the motor or replace it? Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. Some motor failures will require asking fewer than five whys. This is another biggie. c. It abducts the arm. D) Suction pressure goes down and superheat increases. 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. Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? Opens are indicated by infinite resistance or impedance reading. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. 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. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. What is the most likely cause of flames that are lifting off the burner? Sounds simple. Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. All photographs are copyrighted 1985-2019byEASA. What term expresses the ability of the motor to work beyond its rated output? Re-state what you felt caused the failure. We wrap it up by looking at the bigger picture, including how to perform a root cause failure analysis, 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. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. 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. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. 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. 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 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. It should concisely answer what, where, when, how and possibly why. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. In addition, misalignment may feed vibration into both the load and the motor drive shaft. These tools can assess electronic harmonics, distortion, and load studies. Special rates good through June 1. When the winding is energized, it forms magnetic poles. Not so fast. to ask deciding whether to repair or replace your electric motor. 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. a) tight enough so that it does not slip on startup Unfortunately, only the bolted type of compressor can be checked in this manner. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. B) Call the equipment supplier and provide the system model numbers. What is the effect on suction pressure and superheat? All rights are reserved. | Site Design & Development by Human_Code. 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. Cloudflare Ray ID: 7a12d477b814c226 However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. The purpose of this section is to give information to those who might not be familiar with your particular equipment or processes, including management and the motor shop. 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. From its position in the periodic table, determine which atom in each pair is more electronegative: (a) N or P (b) N or Ge (c) S or F (d) Cl or S (e) H or C (f) Se or P (g) C or Si. More than one response required. Do they follow the ANSI/EASA AR100 best practices? It may also occur as a result of excessive starts or reversals. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Some plants prefer to perform their own motor repairs. 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. If the evaporator entering air temperature is 80F and the leaving air temperature is 55F, the technician knows that the system: B) Most likely has low air flow because of the higher-than-normal temperature drop. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. The failure mechanism involves the gradual development of a weakness in the insulation. In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. The ________ is used to identify all the controls in series with the load. The questions are based on these four criteria. 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. Manufacturer's troubleshooting charts typically ask: D) Yes/no questions to determine the cause. How many years of experience do they have? Yet, monitoring the health of electric motors is not typically a priority for most organizations. 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. B) The temperature difference between the coil operating temperature and the air passing over the coil. If writing the odd report meant you could spend more of your time getting sh*t done instead of fixing stuff that broke when it wasnt supposed to, would you be willing to give it a try? Check the bearings to make sure they can spin freely. Larger blower wheels are typically operated by ___________ motors. 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. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Which of the following is (are) true concerning the pectoralis major?

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