Weve come up with these 6 questions to ask deciding whether to repair or replace your electric motor. 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. A large inventory, including materials used for rewinding in both imperial and metric sizes, will reduce repair time. 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. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Bearing failure can be caused by several things: A heavier load than designed for Inadequate or incorrect lubrication Ineffective bearing sealing Shaft misalignment Incorrect fit Normal wear Induced shaft voltages An effective PM program requires a culture change in many companies, but the work is worth it. Timing. Foreign bodies which find their way inside the motor can dent bearing . Performance & security by Cloudflare. Terms and ConditionsCopyright 2016-2021 Duke Electric. 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. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. 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. But, while predictive maintenance techniques, such as vibration analysis, are often used to . Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. and preventive maintenance (PM). Instrument to measure and diagnose: Fluke 810 Vibration Tester. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. 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. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. Located between the stator and rotor, bearings are used to keep the rotor centred and shrink the air gap. Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. Contact us to speak with a specialist. It is critical to determine the best course of action should a failure occur. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Bearings are the culprit in more than half of motor failure cases. 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. How unique is it? Which organizations specify standards for electric motors? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. The resistance of ________ can accurately be predicted using Ohm's law. If the motor is less than 1/8 HP, it is almost always replaced. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. 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. 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. There a few types of misalignment: Impact: Premature wear in mechanical drive components that leads to premature failures, Instrument to measure and diagnose: Fluke 810 Vibration Tester, Fluke 830 Laser Shaft Alignment Tool. c) moisture Do they follow the ANSI/EASA AR100 best practices? 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. Fluke Accelix presents at FM Ireland 2018! Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. Design is critical to the repair-replace decision. To start investigating harmonic distortion, use a power quality analyzer to monitor electrical current levels and temperatures at transformers to be sure that they are not overstressed. 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. 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. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. How efficient is the motor that failed? 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. 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. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. Potential relays measure the back ________ developed across the ________ winding to operate the relay. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. 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. Identify causes you eliminated and why. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. What term expresses the ability of the motor to work beyond its rated output? Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? If the reading is infinite, your motor should be fine. A brush assembly is often used to shift the current. 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? Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. 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. Organize the content under subheadings that make sense. a. Know the breakpoints at which youre willing to repair vs. replace. Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. 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 one horsepower motor with a service factor of 1.2 can safely produce: On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Cost. When replacing fuses be sure to match which of these ratings? 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? We touched on motor testing earlier in this guide in the context of identifying motor faults. Looseness and bearing failures. If they dont pass the test, keep shopping. 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). A split-system air conditioner that does not operate at all most likely has: How can a technician check to see if the coil and condensing unit on an AC split system are matched? Check each wire, including T1, T2, T3 and the ground wire. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. That doesnt mean humans are off the hook, however. Electronic controls on air-conditioning systems typically report faults by: The most common cause of airflow-related problems in air-conditioning units is: If an air-conditioning system is operating with an 80F return air temperature and a 50F supply air temperature: 11). 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. Start by completely disconnecting the spindle motor from all power sources. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. The winding failures illustrated here are typical of what can happen is such circumstances. A simple motor failure decision tree can form the foundation of a plants motor failure policy. Skip to the next section on. Why is that, and which isotope is located near the axis? Special rates good through June 1. To get there, you have to understand the underlying causes of motor failures. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Winding shorted turn-to-turn And so on. Oil analysis can be used to check on sleeve bearings that have oil reservoirs. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. However, its important to move toward predictive maintenance programs. A tri-fold brochure containing the information on this page is available for purchase. Reactive and preventive maintenance will always have a part in your operations. 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. |, free online repair or replace decision-making tool. A) 240 volts. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. It raises the clavicle. 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. Should we repair the motor or replace it? Heres how a motor failure report can help with motor management. 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. 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. Heres an example of the 5 Whys in action. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. What is a common symptom of a severely restricted filter drier? | Site Design & Development by Human_Code. 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). The action you just performed triggered the security solution. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. 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. Then we identify the 5 common causes of industrial motor failure. 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). How long will it take to get the motor repaired? Winding Shorted Turn-to-Turn Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. This additional energy is not used to turn the motor shaft but circulates in the windings and ultimately contributes to internal energy losses. Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. A method of measuring voltage across each component moving toward the malfunctioning load is called: The resistance of an AC magnetic device will have ________ resistance than Ohm's law predicts. 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. Consider the size, age, type and application of your motor. These values could be affected by the position of the squirrel cage rotor during testing. Theres a big difference between reactive maintenance and preventive maintenance (PM). But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? Extent of failure. Will the shop do the work themselves, or will they outsource it? A common cause of an open winding is undersized lead lugs. Weve spent most of this guide talking about what to do when a motor fails. b. 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? Plot individual measurements to establish a baseline trend. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. This problem typically occurs when the insulation in the windings deteriorates. 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 . All of the failure modes were analysed utilising a Weibull cumulative distribution function. 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. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. 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. Opens are indicated by infinite resistance or impedance reading. 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). Excessive motor heat is a major cause of motor failure. Does the shop have a significant amount of experience with your motor? Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. When a motor goes down, someone has to be told. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. 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. Explain why a sample of iron(III) sulfate is uncharged. Either no one bothered to determine why the failure occurred, so Bonnett and Yung didnt have any data to work with, or the investigation failed to determine a cause. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. It can also detect the presence of dirt or moisture. Temperature plays a major role in motor failure. Sales professionals need to keep their skills sharp in order to discover new leads, nurture promising prospects and close more deals. Why. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. 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. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. This website is using a security service to protect itself from online attacks. These tools can assess electronic harmonics, distortion, and load studies. Choose the more stable alkene in each of the following pairs. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. Look on the outside of the motor for other potential problems, like holes or smoke points. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. What is the effect on suction pressure and superheat? Uneven mass in motor windings and other wear-related factors. Already an expert? The correct tension for any belt drive application is: Weve come up with these. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. This report may come from your motor shop. [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. Winding Failures. The ________ is used to identify all the controls in series with the load. Electrical failures disrupt the power supply to the motor. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. Yes, itll require some upfront work. 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. This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. Know the breakpoints at which youre willing to repair vs. replace. 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. 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 single-phased winding failure is the result of an open in one phase of the power supply to the motor. That way your chosen solution doesnt just treat the symptom. 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. The machines provide the data. Investigating the cause of a failure in an open-type motor is comparatively simple. An open winding falls into which general motor failure area? 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 windings account for about 32% of all AC electric motor repairs. However, these tests only provide a "snapshot" of motor health. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. 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 . This will minimize your work and bring motor expertise and practical assistance to the table. Indicate the relative amounts of potential and kinetic energy at each position. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? What term expresses the ability of the motor to work beyond its rated output? b) insulation faults