Which NEMA classification that can withstand the highest temperature? Include data and observations. The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque and overheating. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. All rights are reserved. Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. C) Unusual airflow restrictions in the duct. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. Yet determining the cause is a critical step in protecting your motors. 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! Whats the lead time on a new motor? One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. Which failure could cause nothing to happen when the thermostat is set to heat? PM has been shown to reduce downtime by as much as 50%. Skip to the next section on. What type of drive would move the driven device at the same speed as the motor? A common cause of an open winding is undersized lead lugs. 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). Sounds simple. 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. If the failure was catastrophic, repair may not be a good idea. Why. 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. A brush assembly is often used to shift the current. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. 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. That way you can save your bearing next time, instead of simply having it fail again. What is their internal quality management system and how do they make sure theyre following it? b. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. The key is to dive deeper into understanding why the component failed. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. PM has been shown to reduce downtime by as much as 50%. Some plants prefer to perform their own motor repairs. You can email the site owner to let them know you were blocked. Keep all of your organizations assets up and running without downtime. Three-phase distribution systems often serve single-phase loads. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. Arming maintenance engineers and technicians with the right knowledge, prioritizing workload and managing preventative maintenance to monitor equipment and troubleshoot intermittent, elusive problems can, in some cases, avoid failures due to normal system operating stresses and reduce overall downtime costs. Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. If there is no resistance or the resistance is uneven, the motor is likely faulty. 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. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. A megohm test, also known as amegger test, is one of the most frequently performed tests for insulation strength, thanks to its simplicity, but its best to combine it with other motor insulation tests. 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. Not so fast. 23% Major winding failure [8], 2011 c) Under voltage and Over voltage Unequal voltages usually are caused by unbalanced loads on the power source, a poor connection at the motor terminal, or a high resistance contact (weak spring). Plot individual measurements to establish a baseline trend. a) contamination 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. Organize the content under subheadings that make sense. Weve spent most of this guide talking about what to do when a motor fails. 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 it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. The imagers test faulty connections, overheated bearings, and tank levels. Smith, Michael Abbott. Looseness and bearing failures. A root cause failure analysis can be relatively quick and informal. The resistance of ________ can accurately be predicted using Ohm's law. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. This section is where you give the evidence for the cause of the failure. b) insulation faults Capture and document critical measurements at installation, before and after maintenance and on a routine basis. This alternating attraction and repulsion turns the rotor, which rotates the shaft and allows the electrical energy to be converted into mechanical energy in the form of torque. Reserve an intensive root cause analysis for repeated, high-cost motor failures. b) the minimum tension required to keep the belt from slipping at its maximum torque Once the underlying causes are identified and understood, implementing preventive maintenance procedures through diagnostics testing is the best way to help remedy electric motor winding failures. If the reading is infinite, your motor should be fine. The ________ is used to identify all the controls in series with the load. Chances are, you arent the final decision maker on larger operational and capital expenditures. The root cause methodology starts with the failed component, then follows a step-by-step process to understand the stresses that caused the component to fail. Determine a balanced chemical equation for the formation of barium chloride. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. 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. 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. D) After the draft switch closes to prove the draft. 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. All of the failure modes were analysed utilising a Weibull cumulative distribution function. 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). Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. Shaft failure is the least common cause of motor failure. Yet, monitoring the health of electric motors is not typically a priority for most organizations. c) 1/64th inch deflection per 1 inch span between drive shaft and driven shaft Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. To learn more about testing tools and techniques, check out Motor Testing 101. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. A one horsepower motor with a service factor of 1.2 can safely produce: Manufacturers often recommend adding what component to split systems with unusually long refrigerant lines? The most common types of single phase compressor motors are: Permanent split capacitor (PSC), capacitor start (CS), capacitor start/capacitor run (CSCR), and split phase, Motors with shunted field windings: B) The temperature difference between the coil operating temperature and the air passing over the coil. Once acid is identified in D) The large temperature drop indicates the airflow is less than required. 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? Look on the outside of the motor for other potential problems, like holes or smoke points. The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. 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) 240 volts. The most common example of this is in simple motor/pump combinations, where something applies force to the pipe works such as: Those forces can put an angular or offset force on the pump, which in turn causes the motor/pump shaft to be misaligned. The questions are based on these four criteria. Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. 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. Special rates good through June 1. Cost. 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. The questions are based on these four criteria. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. A tri-fold brochure containing the information on this page is available for purchase. When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. Explain your reasoning. 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. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. c. It abducts the arm. Others will need more than five. 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. near the wall? Are the techs CSA-certified? VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. Larger blower wheels are typically operated by ___________ motors. Electrical failures disrupt the power supply to the motor. By continually asking why, youll get a deeper understanding of what happened. Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. Indicate the relative amounts of potential and kinetic energy at each position. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. Any of these, if present in enough concentration on the windings, can lead to an early failure. Sounds simple. |, free online repair or replace decision-making tool. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. Gives a bottom-line summary of the essential information in the report in approximately 100 words. The knee-jerk conclusion about the cause of the motor failure is often very different from the conclusion a tech will reach after writing a formalized report. A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. When troubleshooting split air conditioning systems be sure to check voltage to: Which of these methods used to determine which component in a circuit is not working properly? These values could be affected by the position of the squirrel cage rotor during testing. Sigma currents are essentially stray currents that circulate in a system. B) Call the equipment supplier and provide the system model numbers. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. 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. Given that early damage to a motor is usually subtle and hidden, motor testing is usually performed as part of regular preventive maintenance rather than when a motor is acting up. Reflections are generated when there is an impedance mismatch between the source and load. The stator is the stationary part of the motor. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. 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 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. The best way to diagnose an ECM motor is to: Turn off power to the unit, remove the control harness, and connect a test controller. , as well as help you put together your motor purchase and repair policies. It may also occur as a result of excessive starts or reversals. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Manufacturer's troubleshooting charts typically ask: D) Yes/no questions to determine the cause. What is the most likely cause of flames that are lifting off the burner? Impact: Accelerated wear on rotating components resulting in bearing failure. 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. Electric motors serve as a critical component for any facility. This website is using a security service to protect itself from online attacks. Nearly all air conditioning condenser fans are ________ motors. Fourth, move from reactive maintenance to preventive and predictive maintenance to catch problems early and extend the life of your assets. Its responsible for 51% of motor failures. 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? The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. 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. A megohmmeter can detect: 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. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. Thermal deterioration of insulation in one phase of the stator winding. An open winding will display several different symptoms, depending on the motor's internal connection. At the simplest level, all three phases of voltage should always have the same magnitude. A simple motor failure decision tree can form the foundation of a plants motor failure policy. An open door switch on a gas furnace will cause: A) A complete system shutdown-no system operation at all. Which of the following is (are) true concerning the pectoralis major? Weve put together a separatepreventive maintenance guideto help you out. Already an expert? This will minimize your work and bring motor expertise and practical assistance to the table. 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. Winding shorted turn-to-turn The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. 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. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. 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). Opens are indicated by infinite resistance or impedance reading. In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. (If youve had small children in your life, youll also have flashbacks.) 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. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). 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. 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. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. Whats the shops inventory of parts and materials for repairs? 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. c) moisture Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. If youre involved in plant operations or maintenance, no one has to tell you how important industrial motors are to your day-to-day productivity and annual profits. Other failures are caused by vibration, physical damage and situations that causes excessive heat. We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Various factors, such as overheating, physical damage . A single-phased winding failure is the result of an open in one phase of the power supply to the motor. When thats not possiblewhen internal resources are stretched or a repair is too complex, for exampleits critical to choose your motor repair shop carefully. Heres how a motor failure report can help with motor management. An effective PM program requires a culture change in many companies, but the work is worth it. 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". 13% of motor failures are caused by bearing failure, and more than 60% of the mechanical failures in a facility are caused by bearing wear, so learning how to troubleshoot this potential problem is important. Everyone is busy. Identify causes you eliminated and why. When an electric motor fails, theres one question that must be answered. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. Potential relays measure the back ______ developed across the _______ winding to operate the relay. De-energized testing runs a motor through its paces while its turned off. 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. 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. b) will not run at full speed or strength Here are some of the more common motor tests to perform regularly as part of your early warning system. Your motor shop can help you. 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. 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. This is another biggie. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Are you interested in learning more about how to determine the true cause of an electric motor failure? The structured process of report writing gets you to think more and differently about what happened. Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. Performance & security by Cloudflare. 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. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Winding Shorted Turn-to-Turn Fluke Accelix presents at FM Ireland 2018! 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. 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.