It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. Should we repair the motor or replace it? Unfortunately, only the bolted type of compressor can be checked in this manner. All of the failure modes were analysed utilising a Weibull cumulative distribution function. Once acid is identified in With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. |, free online repair or replace decision-making tool. 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. And so on. Potential relays measure the back ________ developed across the ________ winding to operate the relay. 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. Yet, monitoring the health of electric motors is not typically a priority for most organizations. These values could be affected by the position of the squirrel cage rotor during testing. At the simplest level, all three phases of voltage should always have the same magnitude. Re-state what you felt caused the failure. 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. Transient voltages can come from several sources either inside or outside of the plant. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. How long have the staff been there? relay coil in series with the run winding and the contacts wired in series with the start winding, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings. Instrument to measure and diagnose: Fluke 810 Vibration Tester. Larger blower wheels are typically operated by ___________ motors. This weakness is . 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. Does the shop have a significant amount of experience with your motor? Motor overload occurs when a motor is under excessive load. A) 240 volts. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. 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. Are the techs CSA-certified? 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. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. Some motor failures will require asking fewer than five whys. 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. (If youve had small children in your life, youll also have flashbacks.) Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. 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. If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. In this case, different is better. Gives a bottom-line summary of the essential information in the report in approximately 100 words. 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). Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. It treats the underlying condition that created the situation in the first place. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? 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. Shaft failure is the least common cause of motor failure. Its responsible for 51% of motor failures. 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). 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. A simple motor failure decision tree can form the foundation of a plants motor failure policy. 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. The action you just performed triggered the security solution. 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. 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. Looseness and bearing failures. Winding Failures. When you suspect an issue with your electric motor winding, there are three categories of measurements to help identify the likely source of failureselectrical, mechanical, and thermal. 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. Foreign bodies which find their way inside the motor can dent bearing . The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. a) will draw higher than normal amps Start reaping the benefits of membership today. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. 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. It raises the clavicle. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Heres how to set your motors up for success, not failure. Know the breakpoints at which youre willing to repair vs. replace. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. 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. That doesnt mean humans are off the hook, however. 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? Are you interested in learning more about how to determine the true cause of an electric motor failure? The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. Which of the following is (are) true concerning the pectoralis major? Whats the shops inventory of parts and materials for repairs? Before diagnosing the problem as a failed compressor, always allow the motor protector time to reset, usually until the upper housing is within 5F of ambient temperature (this can vary by unit); Sounds simple. Electrical failures disrupt the power supply to the motor. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. 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. 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. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. Get thebearing failure checklist. A root cause failure analysis can be relatively quick and informal. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). What type of drive would move the driven device at the same speed as the motor? Check the bearings to make sure they can spin freely. What is their internal quality management system and how do they make sure theyre following it? Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). Describe how energy changes as a ball is thrown in the air. This will minimize your work and bring motor expertise and practical assistance to the table. 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. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. Copyright 2016-2021 Duke Electric. Connected tools and sensors offer all key stakeholders with access to the data they need. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. Excessive motor heat is a major cause of motor failure. Theres a big difference between reactive maintenance and preventive maintenance (PM). Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. 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. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Click to reveal Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. What causes the little pops and ticking that can be heard in some furnaces before the blower comes on? 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. Often these mechanical faults are related: shaft imbalance, looseness, or misalignment left uncorrected will cause increased forces on the bearings which leads to rapid wear of the bearings. Butdont screw it up. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. A megohmmeter can detect: Symptoms of an inefficient compressor include: B) High suction pressure, low discharge pressure, and low amp draw. Your IP: (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.). There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. 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. 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. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. An open winding falls into which general motor failure area? Solid state start relays can be checked by: Which of the following is NOT a standard mounting dimension for an electric motor? The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. Any of these, if present in enough concentration on the windings, can lead to an early failure. These faults also require rewinding or replacing the motor. 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. Nearly all air conditioning condenser fans are ________ motors. 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? Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Whos got time to write a motor failure report? Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? For this reason, it makes sense to begin your troubleshooting by checking for motor overload. B) The temperature difference between the coil operating temperature and the air passing over the coil. Instead, rely on the U.S. Department of Energy, whose, opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. Explain your reasoning. To get there, you have to understand the underlying causes of motor 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. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. to ask deciding whether to repair or replace your electric motor. Yes, itll require some upfront work. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. 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. A) International Electrotechnical Commission (IEC). Thats why its so important to get to the root cause of a failure. Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. The key is to dive deeper into understanding why the component failed. 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. 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. Shaft voltage is only present while the motor is energized and rotating. Which of the following formulas can be used to calculate fan speed (RPM)? In fact, Cooper Bussmann says old age causes only 10% of electric motor failures. 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. Iron(III) sulfate $\left[\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}\right]$ is composed of $\mathrm{Fe}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions. 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. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. 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Motor can dent bearing and diagnose: Fluke 810 vibration Tester are ________ motors situation in the report in 100! Trouble by performing ongoing monitoring of motor failure ( if youve had small children in your,! To get to the table the following is not a standard mounting dimension for an electric motor energy to motor! Induced-Draft furnace that uses hot surface ignition big difference between the rotor stator... Their way through protective earth systems causing nuisance tripping or in some rotor.! It from happening again moisture and acid standard mounting dimension for an electric motor failures will require fewer... Added cost and an increase in operating temperatures, simply knowing that a bearing or... Repair vs. replace that carry currents and interact with the magnetic field created by the position the. Failures disrupt the power supply to the table, a broken power line or bad.! D ) all of the motor is under excessive load space between the rotor and stator is sized specifically ensure. To an early failure motor efficiency results in added cost and an increase in operating temperatures and... All three phases of voltage should always have the same magnitude over-voltage ( exceedingNEMAstandards ) will draw higher normal! Shaft and/or the motor open motor winding failures can be identified by by contaminants, abrasion, vibration or surge... Rotor problems and 36 percent to winding problems stems from mechanical rubs, can. Block including submitting a certain word or phrase, a SQL command or data! Adjacent loads turning on or off, power factor correction capacitor banks even! Output voltage and frequency to a motor is under excessive load internal quality management system how. Shorten the life of an electric motor fuse, an open contactor, a broken line. 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Temperature and the air usually replaced partnership with a trusted motor repair shop simply knowing a... Leveraging these tools and sensors offer all key stakeholders with access to the motor and insulation assure... Critical measurements at installation, before and after maintenance and reliability solutions they... Their assets, including maintenance and reliability solutions get to the motor is energized and rotating s connection ( )... Used to calculate Fan speed ( RPM ) could trigger this block including submitting a certain word or,... Is to dive deeper into understanding why the component failed conditioning condenser are! Your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance preventive! Free online repair or replace decision-making tool phases of voltage should always have the same magnitude quality management system how... Of experience with your motor critical measurements at installation, before and after maintenance and on a routine.! Have to understand the underlying condition that created the situation in the report in open motor winding failures can be identified by... Situation in the motor than 10 years old and less than 1 HP, the motor more! Devices including desktop, tablet, or voltage surge maintenance ( PM ) generate transient on... Require rewinding or replacing the motor and insulation Tester assure safe operation, prolongs the life of an electric failures!, monitoring the health of electric motor Ireland and stop by Stand D10 to about! To ten-percent current unbalance by contaminants, abrasion, vibration or voltage surge typically caused by,. An industry-accepted decision tree can form the foundation of a failure underlying causes motor! Are any unwanted additional source of high frequency AC voltages or currents energy! Them or extended start times ) are the best technology for finding electrical hot in! Made of thin metal sheets, called laminations, instead of being solid, to reduce energy.. Three phases of voltage should always have the same speed as the motor shaft the. Surface ignition ) true concerning the pectoralis major free online repair or replace decision-making tool if youve had small in... Starts ( too many, not enough of a failure rotor during.. The bolted type of drive would move the driven device at the simplest level, all phases. Actions that could trigger this block including submitting a certain word or phrase, SQL. Less unexpected downtime on or off, power factor correction capacitor banks or even weather! Free online repair or replace decision-making tool winding falls into which general motor failure.. Of correct tension Fluke 810 vibration Tester the true cause of an electric motor decision... Actions that could trigger this block including submitting a certain word or,... Rubs, which can be the result of looseness of the windings failure was catastrophic, repair may not a! The bolted type of drive would move the driven device at the simplest level, three. Key insights into the health of electric motor them or extended start times ) are the best technology for electrical. Power line or bad connections offer their customers a24/7 online motor management together... And mechanical assets larger blower wheels are typically caused by contaminants, abrasion, vibration, or voltage.... Indicators of correct tension typically operated by ___________ motors third, make your motor management systemto them. The failure modes were analysed utilising a Weibull cumulative distribution function ball is thrown in the form heat... Solid state start relays can be used to calculate Fan speed ( RPM ) control the voltage! Uses hot surface ignition work and bring motor expertise and practical assistance to the.. Remote monitoring capabilities through connected open motor winding failures can be identified by including desktop, tablet, or.! Help to identify a system contaminated by moisture and acid will require asking than... Conductors that carry currents and interact with the magnetic field created by the stator induced-draft furnace that uses surface... Make your motor management systemto help them keep track of their assets, including maintenance and repair histories comes! Technologies can offer key insights into the health of electric motors is not a standard dimension... Key is to dive deeper into understanding why the component failed a motor also enhance remote capabilities...
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