These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. When ohming components on the system, it is important to: How is the subcooling of an air-conditioning system affected by a restriction in the liquid line? Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. And so on. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors An open internal motor overload is distinguished by: a) measurable resistance between run and start b) infinite resistance between start and common c) infinite resistance between run and common d) all of these d) all of these What is the effect on suction pressure and superheat? Yes, itll require some upfront work. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. 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. Potential relays measure the back ______ developed across the _______ winding to operate the relay. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Every robust PM program will includekeyperformance indicatorsso you can measure success and make improvements. How unique is it? A megohmmeter can detect: This will help you identify patterns with a particular asset and make warranties easy to manage. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Whilevibration analysiscan be used to test critical motors for imbalance, misalignment, mechanical looseness, a bent shaft, critical speeds and more, its particularly helpful with identifying bearing problems. Fault isolation diagrams and troubleshooting tables help the technician locate problems through the process of: The refrigerant condensing temperature for an air-cooled system having a 20F split is: The most common airflow problem experienced on air-conditioning systems is: C) Low airflow caused by dirty or plugged air filters. |, free online repair or replace decision-making tool. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. Indicate the relative amounts of potential and kinetic energy at each position. An open winding falls into which general motor failure area? Sigma currents are essentially stray currents that circulate in a system. Transient voltages can come from several sources either inside or outside of the plant. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. Nearly all air conditioning condenser fans are ________ motors. c) moisture 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. Design is critical to the repair-replace decision. , as well as help you put together your motor purchase and repair policies. 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. Instrument to measure and diagnose: Fluke 810 Vibration Tester. And those issues will have another cause. That way, action can be taken before its too late. Larger blower wheels are typically operated by ___________ motors. 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. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. c) are hard to detect Bearings - 51% Windings - 16% External causes -16% Unknown - 10% Rotor - 5% Shaft or coupling - 2% Repair or replace? 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. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. Weve come up with these. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. 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. 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. In a perfect situation, the sum of the three currents would equal zero. In this case, different is better. B) Call the equipment supplier and provide the system model numbers. Why. A Weibull-shaped parameter in the range of [ 20 ] 2.8-3.0 was used to describe bearing failures and indicated an increasing failure rate and worn-out . Buy copies for your salespeople to distribute to your customers and put your companyfront and center byimprinting your company name, logo or otherinformation on the cover! Performance & security by Cloudflare. Investigating the cause of a failure in an open-type motor is comparatively simple. 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. Document operating condition, machine specifications and performance tolerance ranges. 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. 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. Check each wire, including T1, T2, T3 and the ground wire. 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. Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. This report may come from your motor shop. Terms and ConditionsCopyright 2016-2021 Duke Electric. Then we identify the 5 common causes of industrial motor failure. Sounds simple. We can see your eyes rolling. b. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Everyone is busy. Whats the lead time on a new motor? Instead, rely on the U.S. Department of Energy, whose, opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". If an electrical load in a split-system air conditioner is not working, the technician must determine if the problem is: A) In the load itself or in the switches that control the load. Foreign bodies which find their way inside the motor can dent bearing . a. That way you can save your bearing next time, instead of simply having it fail again. At the simplest level, all three phases of voltage should always have the same magnitude. A) International Electrotechnical Commission (IEC). Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? These faults also require rewinding or replacing the motor. Describe how energy changes as a ball is thrown in the air. In addition, misalignment may feed vibration into both the load and the motor drive shaft. You remove the end bell, and the entire winding can be examined. 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. Motors that sit on resilient rubber wings typically use which type of mounting? B) The temperature difference between the coil operating temperature and the air passing over the coil. 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. The ________ is used to identify all the controls in series with the load. 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. The best way to diagnose an ECM motor is to: D) Turn off power to the unit, remove the control harness, and connect a test controller, Larger blower wheels are typically operated by ________ motors. Does the shop have a significant amount of experience with your motor? Any of these, if present in enough concentration on the windings, can lead to an early failure. Heres how a motor failure report can help with motor management. De-energized testing runs a motor through its paces while its turned off. It raises the clavicle. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. Winding contamination cannot always be readily identified as the root cause of an insulation failure. The structured process of report writing gets you to think more and differently about what happened. Which NEMA classification that can withstand the highest temperature? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. 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. Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. Other tests includeinsulation resistance testing(ensuring the insulation resistance of the motor decreases after it starts),DC step voltage testing(plotting the current that results from increasing the voltage applied to the insulation to look for a non-linear graph),HiPot testing(looking for leakage current as a way of establishing the effectiveness of insulation). It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). When troubleshooting split air conditioning systems be sure to check voltage to: Which of these methods used to determine which component in a circuit is not working properly? This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. Winding Shorted Turn-to-Turn In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. Reactive and preventive maintenance will always have a part in your operations. Which of the following is (are) true concerning the pectoralis major? 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. Its one thing to identify the component thats failed and another thing to isolate the cause of that component failure. D) After the draft switch closes to prove the draft. 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. Troubleshooting motor failure signs to look for, Storing motor in a location without adequate climate control, Corrosion of motor shaft, bearings and rotor, Leakage current from the armature windings (DC motors). When replacing fuses be sure to match which of these ratings? 1 in 10 failures are mysterious. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. This will minimize your work and bring motor expertise and practical assistance to the table. Know the breakpoints at which youre willing to repair vs. replace. Are the techs CSA-certified? Ball bearings are used in smaller motors, while the big boys will have roller bearings. (Here are7 ways to screw up vibration analysis.). The correct tension for any belt drive application is: A) motors, When hopscotch troubleshooting, follow the schematic and move the meter lead on the control side of the circuit from one control to the next, checking the voltage in and out of the control. It treats the underlying condition that created the situation in the first place. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. . Connected tools and sensors offer all key stakeholders with access to the data they need. Reserve an intensive root cause analysis for repeated, high-cost motor failures. Which of the following formulas can be used to calculate fan speed (RPM)? An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? Improve Predictive Maintenance With Thermal Monitoring, Quick Start: Fluke Connect Handheld Tools, Quick Start: Fluke 1742/1746/1748 Three-Phase Power Quality Loggers, causes of electric motor winding failures, Computerized Maintenance Management System (CMMS). Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. 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. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. What is their internal quality management system and how do they make sure theyre following it? We get it. Should we repair the motor or replace it? Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. 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. The key is to dive deeper into understanding why the component failed. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. 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. 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. Shaft voltage is only present while the motor is energized and rotating. Monitoring has two components: inspection and testing. A simple motor failure decision tree can form the foundation of a plants motor failure policy. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Rotating looseness is caused by excessive clearance between rotating and stationary elements of the machine, such as in a bearing. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. Well help you select the right product for your needs. Here is a list of the common winding problems found in an electric motor: Shorted to ground winding 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? 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. Whats the shops inventory of parts and materials for repairs? Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. The root cause methodology starts with the failed component, then follows a step-by-step process to understand the stresses that caused the component to fail. 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Failure decision tree can form the foundation of a break between them or extended start ). A plants motor failure area which of these, if present in concentration... Tightening the mounting feet sits higher than the other three the cause of an failure! Model numbers cause analysis for repeated, high-cost motor failures are typically caused by contaminants, abrasion vibration... Some plants have complex, detailed motor failure always be readily identified as the root cause of a in.