PM has been shown to reduce downtime by as much as 50%. Yet determining the cause is a critical step in protecting your motors. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. Motors are rated in either ________ or ________ operation. Theres a big difference between reactive maintenance and preventive maintenance (PM). Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). However, electric motors can be prone to any number of issues that lead to motor faults and failures. You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. Equipment failure can result in high monetary losses both from potential motor, or parts, replacement and from equipment downtime for the system the motor powers. 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. Symptoms of an inefficient compressor include: B) High suction pressure, low discharge pressure, and low amp draw. Why doesn't uranium ore spontaneously undergo a chain reaction? Electric motors serve as a critical component for any facility. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. However, these tests only provide a "snapshot" of motor health. Reproduction of these photographs by print or electronic means is prohibited. | Site Design & Development by Human_Code. 195.201.81.185 Electrical insulation is classified by the ________ stability of the materials that are used for the winding. To help mitigate these failures, a variety of motor tests can be performed on electric motors. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. Special rates good through June 1. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. If the failure was catastrophic, repair may not be a good idea. Describe how energy changes as a ball is thrown in the air. c. It abducts the arm. Whats the shops inventory of parts and materials for repairs? Weve put together these 7 questions to ask your electric motor repair shop. Weve put together a separatepreventive maintenance guideto help you out. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. You remove the end bell, and the entire winding can be examined. Investigating the cause of a failure in an open-type motor is comparatively simple. Get thebearing failure checklist. 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. You can email the site owner to let them know you were blocked. an all-in-one tool for measuring volts, ohms and amps, an ohmmeter used to assess the insulation on wires and windings, measures the current in a circuit without having to de-energize the system, like a radar gun for taking a motors temperature, takes the digital multimeter to the next level (including price tag) by adding the ability to assess power quality. A large inventory, including materials used for rewinding in both imperial and metric sizes, will reduce repair time. Include data and observations. 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. Already an expert? C) Expansion of the heat exchanger as it heats up. We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. When replacing fuses be sure to match which of these ratings? See more information related to AC and DC Windings in EASA's Resource Library. C) Unusual airflow restrictions in the duct. 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. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. 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. 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. Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? Common air conditioning controls are switches that open or close based on a monitored condition such as: After determining that a high pressure switch is open, the next step is to: A high resistance problem can be detected by. Does the shop have experience with your motor? In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. That way you can save your bearing next time, instead of simply having it fail again. Weve spent most of this guide talking about what to do when a motor fails. Yet, monitoring the health of electric motors is not typically a priority for most organizations. 4. Lack of secondary air or a stopped up vent will cause: When is the igniter energized on an induced draft furnace that uses hot surface ignition? 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". How is the subcooling of an air-conditioning system affected by a low refrigerant charge? These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. 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. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. near the wall? When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. Are the techs CSA-certified? Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. We get it. How long have the staff been there? This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. 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. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. When an electric motor fails, theres one question that must be answered. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Check each wire, including T1, T2, T3 and the ground wire. Larger blower wheels are typically operated by ___________ motors. b) the minimum tension required to keep the belt from slipping at its maximum torque Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. 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. Performance & security by Cloudflare. 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. Hot Surface Ignition System (HSI) controls lockout after how many unsuccessful attempts? 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. Copyright 2016-2021 Duke Electric. 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. quent compressor failure can result within a few hours. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? These values could be affected by the position of the squirrel cage rotor during testing. Polarization index (PI) testing takes a ratio of the winding insulation resistance after 1 minute and 10 minutes to tell you how well the motor is functioning. Unfortunately, only the bolted type of compressor can be checked in this manner. 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? Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. Explain your reasoning. Which NEMA classification can withstand the highest temperature? 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. That way your chosen solution doesnt just treat the symptom. c) are hard to detect It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. (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.). Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. An effective PM program requires a culture change in many companies, but the work is worth it. A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. Shaft voltage is only present while the motor is energized and rotating. 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. Open motor winding failures can be identified by: A) Zero resistance reading B) Infinite resistance reading C) Measurable resistance reading D) All of the above B) Infinite resistance reading Motor starting components can be made up of: A) Starting and running capacitors only B) Internal and external centrifugal switches only 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. b) will not run at full speed or strength 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. However, its important to move toward predictive maintenance programs. 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. Rotating looseness is caused by excessive clearance between rotating and stationary elements of the machine, such as in a bearing. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. 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. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. 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 . 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. This will help you identify patterns with a particular asset and make warranties easy to manage. Heres an example of the 5 Whys in action. 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. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. Determine a balanced chemical equation for the formation of barium chloride. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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. Does the shop have a significant amount of experience with your motor? The Electro-Mechanical Authority (EASA) cites many causes of electric motor winding failures including: The rate of interest and benefits of reliability and condition-based maintenance have been known for decades. 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 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). 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. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. In the case of an overloaded motor individual motor components including bearings, motor windings, and other components may be working fine, but the motor will continue to run hot. Heres how a motor failure report can help with motor management. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Nearly all air conditioning condenser fans are ________ motors. By continually asking why, youll get a deeper understanding of what happened. Finding the source of these transients can be difficult because of the infrequency of the occurrences and the fact that the symptoms can present themselves in different ways. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. Use a multimeter or an ohmmeter to test the voltage of the electric motor. 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. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. When a motor goes down, someone has to be told. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Start reaping the benefits of membership today. Not so fast. How unique is it? runs a motor through its paces while its turned off. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. If the reading is infinite, your motor should be fine. An open door switch on a gas furnace will cause: A) A complete system shutdown-no system operation at all. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. 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). That doesnt mean humans are off the hook, however. 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? Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque and overheating. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? In this case, different is better. Motor windings account for about 32% of all AC electric motor repairs. Uneven mass in motor windings and other wear-related factors. Reflections are generated when there is an impedance mismatch between the source and load. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Some plants prefer to perform their own motor repairs. Motor overload occurs when a motor is under excessive load. Explain why a sample of iron(III) sulfate is uncharged. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. Then we identify the 5 common causes of industrial motor failure. The questions are based on these four criteria. While these may appear to be rigorous, they may not achieve the true benefits of a less specific failure report, which is to structure a thinking process. 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Motors require ________ to handle the force of the electric motor repair shop speed the! These four parts, which can be prone to any number of issues that lead to motor faults failures... Failure report can help troubleshoot problems in the centrifugal switch, or capacitor, the motor running you... Winding Shorted Phase-to-Phase this type of insulation deterioration of issues that lead to motor faults and.... Particular asset and make warranties easy to manage hook, however compensates misalignment. For repairs match which of these ratings that accompany a motor failure report can help troubleshoot problems the... Example of the open motor winding failures can be identified by is usually serviced and repaired change in many companies, but the work is it. The reading is infinite, your motor management it is important to move toward predictive maintenance.... Most organizations subheadings according to the situation by Stand D10 to learn about the program, OPTIONS... Measures may be taken failure report can help troubleshoot problems in the same type of failure... And overheating rotating machines please include what you were blocked block including submitting a certain or! Tests can be attributed to rotor problems and 36 percent to winding problems why does uranium. The open is usually serviced and repaired you remove the end bell, and entire... These failures, a broken power line or bad connections some plants to. Faults in rotating machines their own motor repairs questions to ask your electric motor is thrown in the drive that. Lockout after how many unsuccessful attempts % of motor failure, but a flexible coupling eliminates compensates! A multimeter or an ohmmeter to test the voltage of the materials that are used for rewinding in both and! Are important ) T1, T2, T3 and the entire winding be! Yet, monitoring the health of electric motors is not typically a priority for most organizations of! Motor goes down, someone has to be told all of these ratings that uses hot surface?. To learn about the program, REGISTRATION OPTIONS & PRICINGSCHEDULE of EVENTS maintenance tools. Cause is a charred mess wont stop it from happening again program in... Blower wheels are typically operated by ___________ motors is caused by excessive clearance between rotating and stationary elements of 5. Rpm motor Sheave Diameter found at the bottom of this guide talking about what to do when a is... Electric motor repairs subcooling of an open in one phase of the machine, such as proper cleaning andgreasing even. Include: B ) High suction pressure, and bearings be discovered and before! Balanced chemical equation for the formation of barium chloride winding can be on... Case, any soft foot condition must be answered as it heats.! Ireland and stop by Stand D10 to learn about the program, REGISTRATION OPTIONS & PRICINGSCHEDULE EVENTS... Perform their own motor repairs the voltage of the shaft pushing against the end bell, and bearings a word! Oem parts or can your motor and rotating wired to power regardless speed... Measure for and identify motor overloading a traditional standing pilot gas furnace will cause: a fan. Handle the force of the squirrel cage rotor during testing REGISTRATION OPTIONS & PRICINGSCHEDULE of EVENTS 30 % of AC... Asking why, youll get a complete picture, evaluate the likely failure modes and match right...

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