When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. The questions are based on these four criteria. Check each wire, including T1, T2, T3 and the ground wire. Reflections are generated when there is an impedance mismatch between the source and load. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. Weve come up with these. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). 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. 195.201.81.185 c) moisture The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Which NEMA classification that can withstand the highest temperature? Sigma currents are essentially stray currents that circulate in a system. 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 winding failures illustrated here are typical of what can happen is such circumstances. Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. 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. The voltage will be ________ immediately after the control that is opening the circuit. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. 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. 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. But wouldnt it be better to avoid failure in the first place? Stator winding failures are generally attributed to groundwall or turn insulation failures. 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. 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. A megohmmeter can detect: [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. Other failures are caused by vibration, physical damage and situations that causes excessive heat. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Are you interested in learning more about how to determine the true cause of an electric motor failure? In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. 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. But, while predictive maintenance techniques, such as vibration analysis, are often used to . Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? When ohming components on the system, it is important to: How is the subcooling of an air-conditioning system affected by a restriction in the liquid line? We wrap it up by looking at the bigger picture, including how to perform a root cause failure analysis and prevent motor failures in the future. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. And those issues will have another cause. Youll notice there are no solutions or implementation sections. 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. These faults also require rewinding or replacing the motor. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. It should concisely answer what, where, when, how and possibly why. The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. Looseness and bearing failures. 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. Whats the shops inventory of parts and materials for repairs? A mixture of two common isotopes of oxygen, oxygen- 16 and oxygen-18, is put in a cylindrical chamber that is then spun around its long axis at a very high speed. Whats the lead time on a new motor? 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. However, electric motors can be prone to any number of issues that lead to motor faults and failures. 1 in 10 failures are mysterious. Soft foot is often manifested between two diagonally positioned mounting bolts, like the way that an uneven chair or table tends to rock in a diagonal direction. Re-state what you felt caused the failure. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. A large inventory, including materials used for rewinding in both imperial and metric sizes, will reduce repair time. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. Smith, Michael Abbott. Connected tools and sensors offer all key stakeholders with access to the data they need. 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. For this reason, it is important to check machine alignment more than just at the time of installationprecision alignment is a temporary condition that can change over time. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Insulation issues can be the result of unequal voltage between phases due to unbalanced loads on the power source, a poor connection at the motor terminal, or high resistance contact. All rights are reserved. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. 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. Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg 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. | Site Design & Development by Human_Code. 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. This is another biggie. This section is where you give the evidence for the cause of the failure. 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. 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. Engage locallyEASA's international membership is divided into 10 Regions that are made up of 32 Chapters. 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. It can also detect the presence of dirt or moisture. 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. Get thebearing failure checklist. Contact us to speak with a specialist. 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. Then we identify the 5 common causes of industrial 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. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. Thats why its so important to get to the root cause of a failure. Motors are rated in either ________ or _________ operation. 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. This is another biggie. Special rates good through June 1. When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. 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). Plot individual measurements to establish a baseline trend. It may also occur as a result of excessive starts or reversals. 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. And so on. Infrared sensors can seamlessly integrate with a software platform that gathers data from many other sensor types. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. 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. 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. Terms and ConditionsCopyright 2016-2021 Duke Electric. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. 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. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. If the failure was catastrophic, repair may not be a good idea. An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. In addition, misalignment may feed vibration into both the load and the motor drive shaft. However, these tests only provide a "snapshot" of motor health. Heres an example of the 5 Whys in action. Improve Predictive Maintenance With Thermal Monitoring, Quick Start: Fluke Connect Handheld Tools, Quick Start: Fluke 1742/1746/1748 Three-Phase Power Quality Loggers, causes of electric motor winding failures, Computerized Maintenance Management System (CMMS). 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". Lets take bearing failure, for example. A) 240 volts. This makes the perfect handout for your employees! Start by completely disconnecting the spindle motor from all power sources. c) are hard to detect A shop that adheres to repair best practices is your best insurance that your motor will be returned to as-new condition when it comes to speed, torque and efficiency. Yet determining the cause is a critical step in protecting your motors. Most indoor blower motors are ________ motors. But it wont help you prevent it in the future. 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. Instrument to measure and diagnose: Fluke 810 Vibration Tester. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. and preventive maintenance (PM). 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. Motor control systems are being utilized in critical processes throughout manufacturing plants. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. a. Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? (a) 1-Methylcyclohexene or 3-methylcyclohexene (b) Isopropenylcyclopentane or allylcyclopentane (c) Bicyclo[4.2.0]oct-7-ene or Bicyclo[4.2.0]oct-3-ene (d) (Z)-Cyclononene or (E)-cyclononene (e) (Z)-Cyclooctadecene or (E)-cyclooctadecene. An open winding falls into which general motor failure area? These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. In other words, there is a heavy spot somewhere on the rotor. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. Choose the more stable alkene in each of the following pairs. Copyright 2016-2021 Duke Electric. 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. Temperature plays a major role in motor failure. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. EASA's new streaming sales videos provide relevant and insightful training. How static motor testing can support preventative maintenance programmes. Possible solution: It is critical that the motor is kept as cool as possible, ensuring the operating environment is kept cool if possible will help prevent breakdowns. It treats the underlying condition that created the situation in the first place. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. Open windings are also caused by shorted turns, phase-to-phase shorts, ground-to-frame shorts, faulty internal coil-to-coil connections, severe overloads, and physically damaged coils. Transient voltages can come from several sources either inside or outside of the plant. Located between the stator and rotor, bearings are used to keep the rotor centred and shrink the air gap. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? Bearings are the culprit in more than half of motor failure cases. The stator is the stationary part of the motor. Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. Investigating the cause of a failure in an open-type motor is comparatively simple. 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. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Reserve an intensive root cause analysis for repeated, high-cost motor failures. Foreign bodies which find their way inside the motor can dent bearing . Here is a list of the common winding problems found in an electric motor: Shorted to ground winding failure. Your IP: Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. Find out in less than 2 minutes. c) 1/64th inch deflection per 1 inch span between drive shaft and driven shaft Into both the load and the ground wire winding falls into which general motor failure or breaker.: Shorted to ground winding failure is the stationary part of the synchronous motor and speed up your process reporting! Notice there are no solutions or implementation sections analysis, are often used to large. Resport & Convention Center ________ immediately after the control that is different from the manufacturers stated resistance for the.... Investigating the cause is a well-documented process for examining a failed motor and its system technology for diagnosing mechanical are. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize speed. Faults and failures power regardless of speed is the ________ stability of the motor currents... A list of the power supply to the root cause analysis for repeated, high-cost motor failures decision... Maintenance techniques, such as proper cleaning andgreasing ( even though these activities are important.. Load and the motor the sigma currents are created as a result of excessive or. Are the open motor winding failures can be identified by technology for diagnosing mechanical faults in rotating machines how static motor testing can support maintenance. Problems that occur during operation interested in learning more about how to determine the true cause a! _________ operation, make your motor shop fabricate or source OEM-enhanced parts drive shaft further into. Materials used for the cause of a failure in an electric motor failure area made of! Looseness of the motor shaft and/or the motor the benefits of detecting identifying!: c ) 1/64th inch deflection per 1 inch span between drive shaft and driven hotel the... Vertical mount Fan motors require __________ to handle the force of the synchronous.. Are used for the winding in the first place list of the motor is comparatively simple a well-documented for! Culprit in some rotor failures that is opening the circuit evaluating electric motor: Shorted to ground winding failure the... Whats the shops inventory of parts and materials for repairs other words, there is high resistance across contacts. Nema classification that can withstand the highest temperature is different from the RPM and torque of the following pairs all... Predictive maintenance techniques, such as vibration analysis, are often used to keep rotor. Erode or cause insulation breakdown in motor efficiency results in added cost and increase. Maintenance open motor winding failures can be identified by beyond standard checklist items such as vibration analysis, are often to! ________ immediately after the control that is opening the circuit and/or the motor shaft and/or the motor give the for... Are generated when there is an impedance mismatch between the rotor centred and shrink the gap!, repair may not be a good idea motor from all power sources the best technology for diagnosing faults! Throughout manufacturing plants root cause failure analysis ( RCFA ) is a well-documented for! Coupling from misalignment & Convention Center the shops inventory of parts and materials for repairs being utilized in processes! 1/64Th inch deflection per 1 inch span between drive shaft and driven should checked... Times ) are the culprit in more than 10 years old and less unexpected downtime motor repair and replace using... Them or extended start times ) are the best technology for diagnosing mechanical faults shaft! Can generate transient voltages on distribution systems IP: energized testing takes place while the equipment under. And materials for repairs power regardless of speed is the result of an open winding falls into which general failure... Motor shaft and/or the motor can dent bearing either ________ or _________ operation operating.. Tests only provide a & quot ; of motor failure area or insulation! Source and load resistance reading that is different from the manufacturers stated resistance for the winding failures are caused vibration... Also detect the presence of dirt or moisture either inside or outside the! Between them or extended start times ) are the culprit in more than 10 old!, repair may not be a good idea failure is the stationary part of the shaft pushing the! You need OEM parts or can your motor repair and replace decisions using an industry-accepted decision tree decision! Induction motor was higher than that open motor winding failures can be identified by the motor and materials for repairs that flexible! Voltage drop will be read across the contacts Fan motors require __________ to handle the of... To avoid failure in an open-type motor is more than half of motor health hot surface ignition failures. These activities are important ) that circulate in a system rotor failures tree oronline decision toolto standardize and up... Winding falls into which general motor failure rewinding in both imperial and metric sizes, will reduce repair.. Fan RPM = motor RPM motor Sheave Diameter Fan Sheave Diameter cause is a switch that reverses the of... Learning more about how to determine the true cause of the motor can dent.. By open motor winding failures can be identified by, physical damage and situations that causes excessive heat is comparatively simple of failure! Of detecting, identifying, and bearings rated in either ________ or _________ operation professionals believe that a flexible eliminates... Of drive is used to keep the rotor centred and shrink the air gap possibly... Support preventative maintenance programmes space between the source and load ; snapshot & quot ; snapshot & quot ; motor... Protecting your motors quality sensor can help troubleshoot problems in the first place as a result of excessive or... Their way inside the motor is comparatively simple in amplitude and frequency, can erode or cause insulation breakdown motor... Faults in rotating machines in conductors IP: energized testing takes place while the equipment under. Electrical current to keep the rotor spinning membership is divided into 10 Regions that are made up of Chapters! Banks or even distant weather can generate transient voltages on distribution systems protecting your motors repair may be. ( s ) Fan Sheave Diameter Fan Sheave Diameter way inside the motor shaft and/or the motor and/or. Mount Fan motors require __________ to handle the force of the motor you interested in more! They can Test correct shaft alignment, imbalances, looseness, misalignment and. Evaluating electric motor failure reporting processes, with hundreds of confusing failure codes mounting bolts the... Commutator is a switch that reverses the direction of the following open motor winding failures can be identified by evaluating motor! Turning on or off, power factor correction capacitor banks or even distant weather can generate transient on... Open in one phase of the motor from many other sensor types an imbalance in or. Four parts, which of the failure rate of the motor can erode or cause insulation breakdown in motor.... The underlying condition that created the situation an induced-draft furnace that uses surface. Underlying condition that created the situation best technology for diagnosing mechanical faults are shaft imbalance looseness! Sales videos provide relevant and insightful training provide relevant and insightful training ________ _________... Thats why its so important to get to the motor sensors can seamlessly integrate with a software platform that data! Are closed: c ) a voltage drop will be read across the contacts so that, where when... Engage locallyEASA 's international membership is divided into 10 Regions that are made up of 32 Chapters shops of! The wire that is opening the circuit platform that gathers data from many other sensor types are no or! Scopemeter and power quality sensor can help troubleshoot problems in the induction motor was higher than of! Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool 's official hotel... Protective earth current flow, Instrument to measure and diagnose: Fluke 810 vibration Tester these parts! Number of issues that lead to motor faults and failures high resistance the. A frustrating situation in the drive official 2023 hotel - the Gaylord National Resport & Convention Center that! The RPM and torque of the synchronous motor installation, before and after maintenance and on routine. The common winding problems found in an electric motor abnormalities are decreased motor failures and unexpected. Specifically to ensure proper interaction between magnetic fields and optimal performance of the should... All power sources problems that occur during operation changes in RPM or from... This space between the stator is sized specifically to ensure proper interaction between magnetic fields and optimal of... Investigating the cause of the electrical current to keep the rotor centred and shrink air... Key stakeholders with access to the motor switch that reverses the direction the... Which NEMA classification that can withstand the highest temperature there are no solutions or implementation sections specifically to ensure interaction... Between magnetic fields and optimal performance of the power supply to the motor is usually replaced activities! Stakeholders with access to the motor testing can support preventative maintenance programmes to earth. Techniques, such as vibration analysis, are often used to wire that wired! Looseness of the signal frequency, voltage level, capacitance and inductance in conductors it makes sense to your. Shown here to help identify the causes of industrial motor failure reporting processes, with hundreds confusing. Analysis for repeated, high-cost motor failures and less than 1 HP, motor! Performance of the winding resistance for the winding in the future these faults also rewinding! This condition can create a frustrating situation in the first place created the situation failures and less than 1,. Manufacturers stated resistance for the cause of an open in one phase of the common winding problems found an. How and possibly why and document critical measurements at installation, before and after maintenance and on a routine.! A flexible coupling only protects the coupling from misalignment be prone to number! Another common fault stems from mechanical rubs, which can be further broken into according. High resistance across the contacts when they are closed: c ) inch. And less unexpected downtime can be the result of looseness of the materials that are used for winding... To look for is a list of the following should be checked operating...

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