";s:4:"text";s:10866:"This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. Thats why its so important to get to the root cause of a failure. This website is using a security service to protect itself from online attacks. 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. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. 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. And those issues will have another cause. 195.201.81.185 Skip to the next section on. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. 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. Cost. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. 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. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. Yet, monitoring the health of electric motors is not typically a priority for most organizations. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. 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. A simple way to do a root cause failure analysis is using the 5 Whys technique. Chances are, you arent the final decision maker on larger operational and capital expenditures. 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. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. 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. This includes single-phased winding failures (wye- or delta-connected) caused by an opening from a blown fuse, open contactor, broken power line or bad connection. 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 strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. Plot individual measurements to establish a baseline trend. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. 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. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. What causes the little pops and ticking that can be heard in some furnaces before the blower comes on? Consider the size, age, type and application of your motor. Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. This is the logical outcome, given what youve written in the rest of the report. A common cause of an open winding is undersized lead lugs. The questions are based on these four criteria. 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. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. D) After the draft switch closes to prove the draft. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. This weakness is . Using a decision tree or flow chart takes the guesswork out of the repair-or-replace decision process, making it easy to defend recommendations to management. Describe how energy changes as a ball is thrown in the air. 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 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. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. The questions are based on these four criteria. Electric motors serve as a critical component for any facility. It raises the clavicle. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Contact us to speak with a specialist. 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 The life of a three-phase stator winding can be shortened dramatically when the motor is exposed to unfavorable operating conditions electrical, mechanical or environmental. , as well as help you put together your motor purchase and repair policies. Its one thing to identify the component thats failed and another thing to isolate the cause of that component failure. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg 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). 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. How many years of experience do they have? What type of drive would move the driven device at the same speed as the motor? How unique is it? Check each wire, including T1, T2, T3 and the ground wire. This can lead to bearing destruction within a few months of motor operation. Shaft voltage is only present while the motor is energized and rotating. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Reflections are generated when there is an impedance mismatch between the source and load. 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. 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). Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. Motors are used everywhere in industrial environments and they are becoming increasingly complex and technical, sometimes making it a challenge to keep them running at peak performance. One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. Physical damage, corrosion, improper installation and excessive loads are often the root cause. And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. If they dont pass the test, keep shopping. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. Terms and ConditionsCopyright 2016-2021 Duke Electric. Find out in less than 2 minutes. Look on the outside of the motor for other potential problems, like holes or smoke points. ";s:7:"keyword";s:48:"open motor winding failures can be identified by";s:5:"links";s:687:"Martin's Big Words Read By James Earl Jones,
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