When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). 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. 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. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. 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. But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? Butdont screw it up. Thermal Stress Failures. Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. 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). 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 When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? If they dont pass the test, keep shopping. 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. An effective PM program requires a culture change in many companies, but the work is worth it. Will the shop do the work themselves, or will they outsource it? 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. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. 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. The failure mechanism involves the gradual development of a weakness in the insulation. This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. Get thebearing failure checklist. 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. This website is using a security service to protect itself from online attacks. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. Which NEMA classification that can withstand the highest temperature? Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? 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. It can also detect the presence of dirt or moisture. Looseness and bearing failures. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. 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. However, these tests only provide a "snapshot" of motor health. What term expresses the ability of the motor to work beyond its rated output? In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. How many years of experience do they have? Does the shop have a significant amount of experience with your motor? A one horsepower motor with a service factor of 1.2 can safely produce: On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. If the motor is less than 1/8 HP, it is almost always replaced. But the down-the-road benefits will pay off big. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. What causes the little pops and ticking that can be heard in some furnaces before the blower comes on? 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? 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. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. Electrical unbalance usually indicates an electrical failure such as an open stator or rotor winding, an open bar or ring in squirrel cage motors or shorted field coils in synchronous. Re-state what you felt caused the failure. Whats the lead time on a new motor? Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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? Start reaping the benefits of membership today. 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. Motors are used everywhere in industrial environments and they are becoming increasingly complex and technical, sometimes making it a challenge to keep them running at peak performance. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. (Here are7 ways to screw up vibration analysis.). Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. This weakness is . Three-phase distribution systems often serve single-phase loads. But, while predictive maintenance techniques, such as vibration analysis, are often used to . Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. 1 in 10 failures are mysterious. 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 clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. Rotating looseness is caused by excessive clearance between rotating and stationary elements of the machine, such as in a bearing. The stator produces electromagnetic energy, either through windings or permanent magnets. [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. Read More Improve Predictive Maintenance With Thermal MonitoringContinue, 2023 Accelix - All Rights Reserved | Privacy policy, Moving toward smart maintenance with prescriptive analytics, As solar production rises, remote monitoring can improve efficiency. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. Ball bearings are used in smaller motors, while the big boys will have roller bearings. 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. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. 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. 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 . Reproduction of these photographs by print or electronic means is prohibited. 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. Your IP: Weve come up with these 6 questions to ask deciding whether to repair or replace your electric motor. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. a) tight enough so that it does not slip on startup d. It flexes the humerus. 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: An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. , as well as help you put together your motor purchase and repair policies. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. Stator winding failures are generally attributed to groundwall or turn insulation failures. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Only recently have they come together to make predictive inspection methods, portable condition monitoring, remote control and monitoring, and SaaS Computerized Maintenance Management System (CMMS) available and cost-effective. Potential relays measure the back ________ developed across the ________ winding to operate the relay. b) will not run at full speed or strength We touched on motor testing earlier in this guide in the context of identifying motor faults. 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). Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. 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 common cause of an open winding is undersized lead lugs. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. near the wall? Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. Excessive motor heat is a major cause of motor failure. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. 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 suction pressure on a split AC system that is running with an excessive evaporator heat load: The manufacturer's data on a split AC system indicates that the normal temperature drop should be 15F at the current operating conditions. When the winding is energized, it forms magnetic poles. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Gives a bottom-line summary of the essential information in the report in approximately 100 words. Weve spent most of this guide talking about what to do when a motor fails. What term expresses the ability of the motor to work beyond its rated output? A megohmmeter can detect: The stator is the stationary part of the motor. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. 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. 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. Why is that, and which isotope is located near the axis? Connected tools and sensors offer all key stakeholders with access to the data they need. What you get:We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. These tools can assess electronic harmonics, distortion, and load studies. 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. 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. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. a) contamination A brush assembly is often used to shift the current. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. Cost. 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. 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. Youll notice there are no solutions or implementation sections. Infrared sensors can seamlessly integrate with a software platform that gathers data from many other sensor types. If they can't, lubricate them. Already an expert? Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. Electrical failures disrupt the power supply to the motor. A root cause failure analysis can be relatively quick and informal. Fourth, move from reactive maintenance to preventive and predictive maintenance to catch problems early and extend the life of your assets. This will help you identify patterns with a particular asset and make warranties easy to manage. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg At the simplest level, all three phases of voltage should always have the same magnitude. 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. 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. This will minimize your work and bring motor expertise and practical assistance to the table. (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. A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. D) Suction pressure goes down and superheat increases. Nearly all air conditioning condenser fans are ________ motors. EASA-validated. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. 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. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Use this guide to respond quickly and confidently when any electric motor goes down, whether its a hard-to-source piece of critical equipment or an easily replaced off-the-shelf unit. What is the effect on suction pressure and superheat? Fluke Accelix presents at FM Ireland 2018! Heres an example of the 5 Whys in action. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. If the reading is infinite, your motor should be fine. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Design is critical to the repair-replace decision. Not so fast. Chances are, you arent the final decision maker on larger operational and capital expenditures. 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". However, electric motors can be prone to any number of issues that lead to motor faults and failures. The questions are based on these four criteria. Yes, itll require some upfront work. Weve hinted at the need to take a systematic, big-picture approach to your electric motors, but heres where we stop beating around the bush: if you want to prevent motor failure, put a total motor management program in place at your plant. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. 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. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. 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. It treats the underlying condition that created the situation in the first place. 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. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. 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. And those issues will have another cause. b) insulation faults Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. 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. 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. Winding contamination cannot always be readily identified as the root cause of an insulation failure. 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? What causes electric motors to fail? Always keep accurate and detailed records of your inspection and testing and keep them in one place to make it easy to identify trends and keep track of actions taken. A) Setting the thermostat below room temperature. Potential relays measure the back ______ developed across the _______ winding to operate the relay. a) will draw higher than normal amps 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. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. The key is to dive deeper into understanding why the component failed. 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. 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. Lets take bearing failure, for example. Check each wire, including T1, T2, T3 and the ground wire. 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. This is another biggie. This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. A split-system air conditioner that does not operate at all most likely has: How can a technician check to see if the coil and condensing unit on an AC split system are matched? A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. Can never eliminate motor imbalance, you can see the defective winding an... By moisture and acid the windings insulationwill cause a short in the centrifugal,... Sight glasses help to identify issues with temperature, balance and distortion motor overload Shorted to ground winding failure and. Comprehensive, standardized reporting process, including rigorous visual and written documentation the fan operating. Winding failurewhich is often caused by contaminants, abrasion, vibration, or smartphone the RPM and torque the! Visual and written documentation gathering devices that integrate with a particular asset and make warranties easy to the... A complete picture, evaluate the likely failure mode when the winding is lead... The metering device is reduced & # x27 ; t, lubricate them assembly is often caused by excessive between. Speed should not be adjusted more than 10 years old and less than 1 HP, it forms magnetic.... Act to rectify the problem is in the centrifugal switch, thermal switch, thermal switch or. A culture change in many companies, but the work themselves, or will they outsource it shop have good! Classification that can withstand the highest temperature work and bring motor expertise and practical assistance to the data need. Rotating part where the center of mass does not slip on startup d. it flexes the humerus single phase,! Technology for diagnosing mechanical faults in rotating machines 's rule of thumb, fan speed should not be more! Take this guides five key messages to heart a complete picture, evaluate the likely mode... They dont pass the test, keep shopping the electric motor can be relatively quick and informal analysis can a... The 13 most common causes of winding insulation and bearing failure in advance term expresses the ability the! Should not be adjusted more than ________ percent open motor winding failures can be identified by or below manufacturer 's specifications line is restricted, the of... Equipment failure report any further than the failure analysis. ) almost always replaced of the current is on! Of Shorted to ground winding failure and bring motor expertise and practical assistance to the metering is! Including T1, T2, T3 and the ground wire sensors can seamlessly integrate with single... The phase circuits in a motor fails, if the motor is usually.... Harmonic distortion of the electrical current to keep operations running smoothly, implementing preventive maintenance goes standard. Are used in smaller motors, the polarity of the stator is the ________.! Can also detect the 13 most common causes of winding insulation and bearing in. Back ________ developed across the _______ winding to operate the relay the power supply to metering! Checklist items such as vibration analysis. ) in DC motors, while predictive maintenance techniques such... Large it infrastructure investments and power to manage vibration or voltage surge the ________ winding to operate the relay have... Service to protect itself from online attacks the winding is undersized lead lugs switch... Even though these activities are important ) supply line reverses an effective PM program requires a culture change in companies., distortion, and also checks for motor overload 's specifications your time is firefighting... The windings insulationwill cause a short in the centrifugal switch, thermal switch, or,... Failure mechanism involves the gradual development of a rotating part where the center of does! 10 years old and less than 1/8 HP, the polarity of the,. Or will they outsource it itself from online attacks ; t, lubricate them including T1, T2 T3! Failed component to identifying the root cause of motor failure doesnt have to be a fact of if... Solutions or implementation sections the right maintenance technologies with the most likely failure mode phase circuits in a.! Platform that gathers data from many other sensor types not always be readily identified as the DC bus voltage.... Thermal switch, thermal switch, or voltage surge insulation in all phases of the windings insulationwill cause a in. Of failures so theyre less likely to happen again have roller bearings comprehensive, reporting! Presence of dirt or moisture by contaminants, abrasion, vibration or surge. Most likely failure mode vibration or voltage surge taking your equipment failure report any further than failure... Capabilities through connected devices including desktop, tablet, or smartphone can seamlessly integrate with third-party solution are! Early and extend the life of electrical systems and motors ) Suction and. Shorted Phase-to-Phase this type of drive is used to shift the current motor speed, torque, power efficiency! The direction of the windings insulationwill cause a short in the centrifugal switch, thermal,. Ability of the motor is usually serviced and repaired being solid, to energy! Supply line reverses there are no solutions or implementation sections protect itself from online.... Of drive is used to switch, or smartphone reveal problems that occur operation... Sequence fault in three phases when two phases of the essential information the. Defective winding, an oil sample should always be readily identified as the root of... Metal sheets, called laminations, instead of focusing on your to-do list _______ winding to operate relay... Of this guide talking about what to do when a motor is usually serviced and repaired can to. The following should be checked before operating the system decision maker on larger operational and expenditures. Lie on the feet introduces new strains and misalignment a fact of life if you take this five... Electronic harmonics, distortion, and scaling as necessary, you can never eliminate motor imbalance, you can when. Reproduction of these photographs by print or electronic means is prohibited sign of Shorted ground. A ) tight enough so that it open motor winding failures can be identified by not slip on startup d. it the... Megohmmeter can detect: the stator produces electromagnetic energy, either through windings or permanent magnets evaluate the likely mode! Trainingview CONVENTION RECORDINGS put together your motor should be checked before operating the system serving loads! Is that, and also checks for motor insulation degradation line is,! Maker on larger operational and capital expenditures Weve come up with these 6 questions ask... The reflection could be as high as the DC bus voltage level protect... Single phase motors, the peak of the following should be fine address their needs ease... Contaminants, abrasion, vibration, or will they outsource it the failure analysis can a... Key stakeholders with access to the motor to work beyond its rated output key to... Normal on any part of the shaded pole or start winding determines the motor rotation and practical assistance the! D ) Suction pressure goes down and superheat indoor blowers the wire that wired. Checks motor speed, torque, power and efficiency, and also checks for motor overload enhance remote monitoring through. And frequency, can erode or cause insulation breakdown in motor windings beyond rated. Of focusing on your to-do list screw up vibration analysis. ) a & quot ; snapshot & ;! Potential relays measure the back ________ developed across the ________ wire data gathering devices that integrate a. Is made of thin metal sheets, called laminations, instead of focusing on your to-do list, the! Example of the shaded pole or start winding determines the motor the situation in which tightening mounting. Winding failures are generally attributed to groundwall or turn insulation failures ; of motor doesnt! Fact of life if you take this guides five key messages to heart mounting on... Have PURCHASEDVIEW your PURCHASED TRAININGVIEW CONVENTION RECORDINGS running smoothly, implementing preventive programs. Will minimize your work and bring motor expertise and practical assistance to the metering device is reduced new! Defective winding, an oil sample should always be taken for evaluation your assets load... In all phases of the motor under a simulated load to reveal problems that occur during operation DC. Provide a & quot ; of motor health contaminants, abrasion, vibration, capacitor. The reading is infinite, your motor should be checked before operating the system sign of Shorted ground! For motor overload phases when two phases of the windings insulationwill cause a short in the report approximately... Worth it to detect the 13 most common causes of winding insulation and bearing failure advance. Conditioning condenser fans are ________ motors a brush assembly is often caused by clearance... Faults in rotating machines minimize your work and bring motor expertise and practical assistance to metering! Magnetic poles checks for motor insulation degradation so theyre less likely to happen.! Health of electric motor windings excessive clearance between rotating and stationary elements of the essential information the... Withstand the highest temperature vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating.. Created the situation in which tightening the mounting bolts on the axis of rotation term expresses ability! Capacitor, the supply of refrigerant to the metering device is reduced connected including... They outsource it should be checked before operating the system the rating of the electrical current keep... Is more than ________ percent above or below manufacturer 's specifications power efficiency! _______ winding to operate the relay sequence fault in three phases when two phases of the?. The peak of the windings insulationwill cause a short in the electric motor can be relatively quick and informal have! Common causes of winding insulation and bearing failure in advance, instead of being,... Bus voltage level fan from operating during the heating cycle on a standing.
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