open motor winding failures can be identified by
If the reading is infinite, your motor should be fine. There are two kinds of soft foot: In both cases, soft foot can be caused either by an irregularity in the machine mounting feet, or in the mounting foundation upon which the feet rest. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. Explain your reasoning. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. Theres a big difference between reactive maintenance and preventive maintenance (PM). c) moisture 195.201.81.185 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. Stator winding failures are generally attributed to groundwall or turn insulation failures. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Nearly all air conditioning condenser fans are ________ motors. This weakness is . d) can be detected by comparing the actual winding resistance to the motor manufacturer's data After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. 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. A tri-fold brochure containing the information on this page is available for purchase. 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? 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. Ball bearings are used in smaller motors, while the big boys will have roller bearings. The failure mechanism involves the gradual development of a weakness in the insulation. 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). Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. 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 . Impact: Premature wear on motor electrical and mechanical components leading to permanent failure, Instrument to measure and diagnose: Fluke Ti480 PRO Infrared Camera, Fluke 289 True-RMS Industrial Logging Multimeter. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. Re-state what you felt caused the failure. Excessive motor heat is a major cause of motor failure. When thats not possiblewhen internal resources are stretched or a repair is too complex, for exampleits critical to choose your motor repair shop carefully. Keep all of your organizations assets up and running without downtime. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. 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. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. Motors are rated in either ________ or _________ operation. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). You can email the site owner to let them know you were blocked. More than one response required. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. Start by completely disconnecting the spindle motor from all power sources. If they dont pass the test, keep shopping. Connected tools and sensors offer all key stakeholders with access to the data they need. Thermal Stress Failures. 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. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Include data and observations. This will appear as an open circuit condition across the motor winding. 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. A simple motor failure decision tree can form the foundation of a plants motor failure policy. Looseness and bearing failures. The winding failures illustrated here are typical of what can happen is such circumstances. Youll notice there are no solutions or implementation sections. In addition, misalignment may feed vibration into both the load and the motor drive shaft. What term expresses the ability of the motor to work beyond its rated output? Choose the more stable alkene in each of the following pairs. Impact: Accelerated wear on rotating components resulting in bearing failure. In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. A megohmmeter can detect: The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. 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. Yet, monitoring the health of electric motors is not typically a priority for most organizations. A root cause failure analysis can be relatively quick and informal. b. That way, action can be taken before its too late. This section is where you give the evidence for the cause of the failure. 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. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. An effective PM program requires a culture change in many companies, but the work is worth it. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Electric motors serve as a critical component for any facility. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. If its a mission critical motor and downtime is costing the company big, is a spare available while you wait for a repair or replacement? 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. There could also be thermal deterioration in all phases of the stator winding typically due to load demands exceeding the rating of the motor or by very high currents in the stator winding due to a locked rotor. A. Bonnett and C. Yung famously compiled survey data and identified the five most common causes of electric motor failure, which can be linked to stresses related to normal operation as well as flukes. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. A) Setting the thermostat below room temperature. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Then we identify the 5 common causes of industrial motor failure. 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. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. Start reaping the benefits of membership today. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Various factors, such as overheating, physical damage . 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. 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. b) insulation faults Click to reveal An open winding will display several different symptoms, depending on the motor's internal connection. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Yes, itll require some upfront work. 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. 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. In fact, Cooper Bussmann says old age causes only 10% of electric motor failures. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. 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. runs a motor through its paces while its turned off. (Note: almost all misalignment is compound misalignment, but practitioners talk about misalignment as the two separate types because it is easier to correct a misalignment by addressing the angular and parallel components separately.). Simply saying the cause of a motor failure was bearing failure may be true. Its up to the maintenance or operations team to interpret it based on baseline information about the equipment and understanding of what a particular test can tell us (and what it cant). Insulation failures like this usually are caused by voltage surges. Find out in less than 2 minutes. Misalignment occurs when the motor drive shaft is not in correct alignment with the load, or the component that couples the motor to the load is misaligned. 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. 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 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. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. C) Unusual airflow restrictions in the duct. 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. You remove the end bell, and the entire winding can be examined. 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. For decades, plant personnel have performed insulation resistance tests with handheld megohmmeters to prevent motor failures that lead to costly unplanned shutdowns, failure-to-produce penalties and rewinding repairs. 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. Whats the lead time on a new motor? Does the shop have a significant amount of experience with your motor? Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. Well help you select the right product for your needs. Which failure could cause nothing to happen when the thermostat is set to heat? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. Are you interested in learning more about how to determine the true cause of an electric motor failure? Fluke Reliability helps you find the best solutions for your electric motor problems. Not so fast. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. Motor windings account for about 32% of all AC electric motor repairs. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. How unique is it? Performance & security by Cloudflare. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. 4. Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? In other words, there is a heavy spot somewhere on the rotor. However, its important to move toward predictive maintenance programs. A common cause of an open winding is undersized lead lugs. It may also occur as a result of excessive starts or reversals. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. Do they follow the ANSI/EASA AR100 best practices? 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 Organize the content under subheadings that make sense. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. 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. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. The correct tension for any belt drive application is: D) All of the these are indicators of correct tension. 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. D) After the draft switch closes to prove the draft. 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. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. |, free online repair or replace decision-making tool. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. What is the effect on suction pressure and superheat? Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. This problem typically occurs when the insulation in the windings deteriorates. Skip to the next section on common causes of electric motor failure. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. What is a common symptom of a severely restricted filter drier? CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. Heres how a motor failure report can help with motor management. Up to 30 per cent of failures the direction of the electrical to! 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open motor winding failures can be identified by