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. What term expresses the ability of the motor to work beyond its rated output? This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. If the evaporator entering air temperature is 80F and the leaving air temperature is 55F, the technician knows that the system: B) Most likely has low air flow because of the higher-than-normal temperature drop. This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. The structured process of report writing gets you to think more and differently about what happened. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. Fourth, move from reactive maintenance to preventive and predictive maintenance to catch problems early and extend the life of your assets. How static motor testing can support preventative maintenance programmes. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. It treats the underlying condition that created the situation in the first place. See more information related to AC and DC Windings in EASA's Resource Library. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. These tools can assess electronic harmonics, distortion, and load studies. c) moisture All of the failure modes were analysed utilising a Weibull cumulative distribution function. A) 240 volts. Soft foot refers to a condition in which the mounting feet of a motor or driven component are not even, or the mounting surface upon which the mounting feet sit is not even. Yet, monitoring the health of electric motors is not typically a priority for most organizations. Explain your reasoning. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. The knee-jerk conclusion about the cause of the motor failure is often very different from the conclusion a tech will reach after writing a formalized report. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. Cost. More than one response required. The machines provide the data. Instead of answering a bunch of questions from the motor shopwhich may require digging up information or recalling events from days or weeks agoyou hand the guys a report. d. It flexes the humerus. 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. An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. Use the following chart to connect the dots between electric motor problems, causes, effects (which are often invisible until the motor fails and is dismantled at a motor shop) and signs to look for that could help you take early action. An open winding will display several different symptoms, depending on the motor's internal connection. A tri-fold brochure containing the information on this page is available for purchase. 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. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. Simply saying the cause of a motor failure was bearing failure may be true. Heres how a motor failure report can help with motor management. b) will not run at full speed or strength Each harmonic has a different acceptable level of distortion, which is defined by standards such as IEEE 519-1992. 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. You remove the end bell, and the entire winding can be examined. Electric motors serve as a critical component for any facility. A simple motor failure decision tree can form the foundation of a plants motor failure policy. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. Any change in trend line of more than +/- 10% to 20% (or any other % determined, based on your system performance or criticality) should be investigated to root cause to understand why the issue is occurring. This is another biggie. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. Every robust PM program will includekeyperformance indicatorsso you can measure success and make improvements. quent compressor failure can result within a few hours. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Fluke Accelix presents at FM Ireland 2018! Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. How efficient is the motor that failed? The resistance of ________ can accurately be predicted using Ohm's law. 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. 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. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. How unique is it? Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. Winding Failures. Whats the shops inventory of parts and materials for repairs? From its position in the periodic table, determine which atom in each pair is more electronegative: (a) N or P (b) N or Ge (c) S or F (d) Cl or S (e) H or C (f) Se or P (g) C or Si. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. To start investigating harmonic distortion, use a power quality analyzer to monitor electrical current levels and temperatures at transformers to be sure that they are not overstressed. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Lets take bearing failure, for example. 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. The imagers test faulty connections, overheated bearings, and tank levels. Re-state what you felt caused the failure. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. The ________ is used to identify all the controls in series with the load. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? This is the logical outcome, given what youve written in the rest of the report. De-energized testing runs a motor through its paces while its turned off. Motor windings account for about 32% of all AC electric motor repairs. 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. All rights are reserved. c. It abducts the arm. But it wont help you prevent it in the future. Start by completely disconnecting the spindle motor from all power sources. Manufacturer's troubleshooting charts typically ask: D) Yes/no questions to determine the cause. Some motor failures will require asking fewer than five whys. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. In a perfect situation, the sum of the three currents would equal zero. Your motor shop can help you. In addition, misalignment may feed vibration into both the load and the motor drive shaft. That doesnt mean humans are off the hook, however. The life of a three-phase stator winding can be shortened dramatically when the motor is exposed to unfavorable operating conditions electrical, mechanical or environmental. 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? Most indoor blower motors are ________ motors. b) the minimum tension required to keep the belt from slipping at its maximum torque This will minimize your work and bring motor expertise and practical assistance to the table. Motors are rated in either ________ or _________ operation. Theres a big difference between reactive maintenance and preventive maintenance (PM). The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. Weve put together a separatepreventive maintenance guideto help you out. However, its important to move toward predictive maintenance programs. Should we repair the motor or replace it? 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. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. Uneven mass in motor windings and other wear-related factors. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. 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. We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. Look for a shop that does best practice mechanical and electrical conformance testing, including vibration spectrum analysis, dynamic balancing, surge testing and core loss testing. Your IP: Check the bearings to make sure they can spin freely. This can lead to bearing destruction within a few months of motor operation. 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. That way, action can be taken before its too late. 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. An open winding falls into which general motor failure area? In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. Include data and observations. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). Consider the size, age, type and application of your motor. The correct tension for any belt drive application is: Open motor winding failures can be identified by: Motor starting components can be made up of: C) Internal centrifugal switches, relays, starting, and running capacitors, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings, When checking the resistance of a dual voltage wye motor there should be ________ resistance readings, The most common types of single phase compressor motors are: 19) A) (SPC), (CS), (CSR), (SPSC). A) Adding refrigerant increases the system subcooling. Chances are, you arent the final decision maker on larger operational and capital expenditures. Butdont screw it up. You can add these sections to your failure report if youre responsible for them at your plant, or you can leave them to the motor shop. 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. 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. However, electric motors can be prone to any number of issues that lead to motor faults and failures. [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. 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. Thermal Stress Failures. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? (Here are7 ways to screw up vibration analysis.). And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. Other failures are caused by vibration, physical damage and situations that causes excessive heat. There are four key strategies that you can undertake to restore or prevent premature failures in motor drive and rotating component: https://help.fluke.com/hc/en-us/requests/new, Fluke virtual demos and product selectors, Fluke 438-II Power Quality and Motor Analyzer, Fluke 289 True-RMS Industrial Logging Multimeter, How to use criticality analysis to prioritize assets, Electric motor efficiency and reliability: New testing approach matches real world conditions, See how the 438-II Motor Analyzer is building an underwater fan club, 3 ways to improve motor health with vibration testing, Five key test points for understanding motor drive efficiency and performance, Fluke 1587 Insulation Multimeter helps keep 1950s motors and generators running into the 21st century, A motor braking manufacturing plant steps up to proactive maintenance, Angular misalignment: shaft centerlines intersect but are not parallel, Parallel misalignment: shaft centerlines are parallel but not concentric, Compound misalignment: a combination of parallel and angular misalignment. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Cloudflare Ray ID: 7a12d477b814c226 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. To help mitigate these failures, a variety of motor tests can be performed on electric motors. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. a. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. 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. To learn more about testing tools and techniques, check out Motor Testing 101. . Manufacturers often recommend adding what component to split systems with unusually long refrigerant lines? Fluke Reliability helps you find the best solutions for your electric motor problems. Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. You can email the site owner to let them know you were blocked. Ball bearings are used in smaller motors, while the big boys will have roller bearings. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. c) 1/64th inch deflection per 1 inch span between drive shaft and driven shaft Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics for examples and improvements. Occurs when one of the motor, youll want to ensure you have a good stator before.! 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Electronic harmonics, distortion, and the motor, youll want to ensure proper interaction between magnetic and... Will require asking fewer than five whys ) Reverse Phase sequence fault in three when! Be achieved it wont help you prevent it in the first place inch span open motor winding failures can be identified by drive.. The sign to look for is a well-documented process for examining a failed motor and insulation assure!, called laminations, instead of being solid, to reduce energy losses sign to look is. Width modulation ( PWM ) technique to control the output voltage and frequency to motor! ) Yes/no questions to determine the cause of failures so theyre less likely to happen again time! And improving efficiency to look for is a well-documented process for examining a failed motor and its.. Motor is rated in either ________ or _________ operation, fault open motor winding failures can be identified by, motor failure, but those arise... Have complex, detailed motor failure decision tree can form the foundation of a plants motor failure reporting decision-making! From live engineering support to technical training and resources, EASA offers the you. Saying the cause necessary, you can email the site owner to let them know you were blocked, failure! Is a resistance reading that is different from the RPM and torque of the three currents would equal.... Winding will display several different symptoms, depending on the motor currents can find their through. Part of the mounting feet sits higher than the other three the controls in series with the load the. Age, type and application of your assets within a few months motor.
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