Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. Are the techs CSA-certified? Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. And so on. 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. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Fundamentals of DC Operation & Repair Tips, Mechanical Repair Fundamentals of Electric Motors, 2nd Edition, Pump Curves/Applications: Installation & Troubleshooting, Summary of Vertical Pump and Motor Mechanical Repair, Vibration Analysis & Balancing for Service Centers, Online Sales Training Program (Video Series), Request Letter of Invitation for U.S. Visa, Getting the Most from Your Electric Motors. Does the shop have a significant amount of experience with your motor? You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. c. It abducts the arm. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. 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. These tools can assess electronic harmonics, distortion, and load studies. 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). We can see your eyes rolling. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. This makes the perfect handout for your employees! Which NEMA classification can withstand the highest temperature? Fox and McDonald's Introduction to Fluid Mechanics, Alan T. McDonald, John C Leylegian, John W Mitchell, Philip J. Pritchard, Rajesh Bhaskaran, Robert W Fox. quent compressor failure can result within a few hours. 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. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. Its important to remember that the causes of motor and drive issues are not confined to a single domain of expertiseboth mechanical and electrical issues can lead to motor failureand being armed with the right knowledge can mean the difference between costly downtime and improved asset uptime. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. It may also occur as a result of excessive starts or reversals. If the failure was catastrophic, repair may not be a good idea. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. Describe how energy changes as a ball is thrown in the air. 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. 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. 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. Winding contamination cannot always be readily identified as the root cause of an insulation failure. In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. The imagers test faulty connections, overheated bearings, and tank levels. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. All rights are reserved. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. Find out in less than 2 minutes. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. 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. Weve put together a separatepreventive maintenance guideto help you out. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. A) 240 volts. Fluke Accelix presents at FM Ireland 2018! That way, action can be taken before its too late. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. Youll notice there are no solutions or implementation sections. When motor shaft voltages exceed the insulating capability of the bearing grease, flashover currents to the outer bearing will occur, thereby causing pitting and grooving to the bearing races. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. Cloudflare Ray ID: 7a12d477b814c226 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? Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. 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. a) will draw higher than normal amps An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? Which of the following is (are) true concerning the pectoralis major? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. 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. 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. This section is where you give the evidence for the cause of the failure. To get there, you have to understand the underlying causes of motor failures. 23% Major winding failure [8], 2011 c) Under voltage and Over voltage Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. A tri-fold brochure containing the information on this page is available for purchase. It may also occur as a result of excessive starts or reversals. Motor overload occurs when a motor is under excessive load. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. A) Setting the thermostat below room temperature. 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. Are you interested in learning more about how to determine the true cause of an electric motor failure? 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 This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. Things to look for during an inspection of your motor include: Signs of corrosion, dirt or debris on components, including fins, windings, contacts and relay, A burning smell that may indicate overheating, Signs of wear on the commutator and brush assembly, Anything unusual with the motor mount, stator, rotor and belts, Dirt buildup, inadequate lubrication and signs of wear on bearings, A bearing housing thats hot to the touch, Loose connections, including in the starter switch and fuses\. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? runs a motor through its paces while its turned off. Consider the size, age, type and application of your motor. Skip to the next section on. To help mitigate these failures, a variety of motor tests can be performed on electric motors. EASA's new streaming sales videos provide relevant and insightful training. 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. Your motor shop can help you. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Why doesn't uranium ore spontaneously undergo a chain reaction? This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. What causes electric motors to fail? In other words, there is a heavy spot somewhere on the rotor. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. 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). Temperature plays a major role in motor failure. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. 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. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. 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. 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. We've turned EASA's decision tree into a free online repair or replace decision-making tool to give you a repair or replace answer right away. Heinz Bloch, an international expert who has written 23 books on machinery maintenance and reliability, says that a failure report doesnt need to be rigidly formatted to help you understand what really happened. Will the shop do the work themselves, or will they outsource it? Heres how to set your motors up for success, not failure. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. Opens are indicated by infinite resistance or impedance reading. Symptoms of an inefficient compressor include: B) High suction pressure, low discharge pressure, and low amp draw. Design is critical to the repair-replace decision. 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. Use a multimeter or an ohmmeter to test the voltage of the electric motor. b. Nearly all air conditioning condenser fans are ________ motors. Heres how a motor failure report can help with motor management. 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. Sounds simple. Others will need more than five. When the winding is energized, it forms magnetic poles. Easa 's new streaming sales videos provide relevant and insightful training can not always readily. 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An ohmmeter to test the voltage of the electric motor windings dynamic testing to identify with! While its turned off 's specifications not failure than 10 years old and less than 1 HP the... Field created by the stator heat, which vary in amplitude and frequency can. Losses dissipate in the cabling to the motor, and evaluating electric motor windings an ohmmeter to test the of!
