These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. That doesnt mean humans are off the hook, however. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? All rights are reserved. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. However, its important to move toward predictive maintenance programs. Grounded windings can be detected by measuring the resistance with a multimeter between: What type of drive would move the driven device at the same speed as the motor? After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. 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. Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. 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. (Here are7 ways to screw up vibration analysis.). Physical damage, corrosion, improper installation and excessive loads are often the root cause. Chances are, you arent the final decision maker on larger operational and capital expenditures. 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\. The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Contamination from dust, dirt and chemicals is one of the leading causes of motor failure. If the motor is less than 1/8 HP, it is almost always replaced. Its responsible for 51% of motor failures. It adducts the humerus. quent compressor failure can result within a few hours. 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. c) moisture The first signs of this problem will be noise and overheating as the bearings begin to lose their original shape and metal fragments mix with the grease and increase bearing friction. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. To help mitigate these failures, a variety of motor tests can be performed on electric motors. Cost. The imagers test faulty connections, overheated bearings, and tank levels. A tri-fold brochure containing the information on this page is available for purchase. Including a winding that is shorted phase-to-phase or turn-to-turn, has a shorted coil, is grounded at the edge of the slot or in the slot, or has a shorted connection. All photographs are copyrighted 1985-2019byEASA. a) contamination Describe how energy changes as a ball is thrown in the air. 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). Ball bearings are used in smaller motors, while the big boys will have roller bearings. Larger blower wheels are typically operated by ___________ motors. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). 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". Capture and document critical measurements at installation, before and after maintenance and on a routine basis. When the winding is energized, it forms magnetic poles. 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. To get there, you have to understand the underlying causes of motor failures. This will appear as an open circuit condition across the motor winding. How long have the staff been there? Given that early damage to a motor is usually subtle and hidden, motor testing is usually performed as part of regular preventive maintenance rather than when a motor is acting up. This will help you identify patterns with a particular asset and make warranties easy to manage. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. If the failure was catastrophic, repair may not be a good idea. 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. 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. Iron(III) sulfate $\left[\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}\right]$ is composed of $\mathrm{Fe}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions. Consider the size, age, type and application of your motor. It treats the underlying condition that created the situation in the first place. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. Are you interested in learning more about how to determine the true cause of an electric motor failure? 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. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. These tools can assess electronic harmonics, distortion, and load studies. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. 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. An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. Should we repair the motor or replace it? Your motor shop can help you. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. 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. EASA-validated. In other words, the return current from the drive would be equal to the current to the drive. Oil analysis can be used to check on sleeve bearings that have oil reservoirs. However, these tests only provide a "snapshot" of motor health. Already an expert? Transient voltages can come from several sources either inside or outside of the plant. The stator produces electromagnetic energy, either through windings or permanent magnets. A) International Electrotechnical Commission (IEC). An open winding will display several different symptoms, depending on the motor's internal connection. 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. Various factors, such as overheating, physical damage . Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. Sigma currents are essentially stray currents that circulate in a system. The ________ is used to identify all the controls in series with the load. That way you can save your bearing next time, instead of simply having it fail again. Which organizations specify standards for electric motors? Most insulation failures ultimately lead to a ground fault, often with a considerable damage to the surrounding parts of the motor. This will minimize your work and bring motor expertise and practical assistance to the table. D) The large temperature drop indicates the airflow is less than required. 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. And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. 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. 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. 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. Some plants prefer to perform their own motor repairs. Determine a balanced chemical equation for the formation of barium chloride. c. It abducts the arm. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. Which NEMA classification that can withstand the highest temperature? In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. Unequal voltages usually are caused by unbalanced loads on the power source, a poor connection at the motor terminal, or a high resistance contact (weak spring). 1 in 10 failures are mysterious. Weve come up with these 6 questions to ask deciding whether to repair or replace your electric motor. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. Not so fast. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. A common cause of an open winding is undersized lead lugs. Explain your reasoning. 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? Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. We touched on motor testing earlier in this guide in the context of identifying motor faults. Most problems with single-phase motors involve the centrifugal switch, thermal switch, or capacitor(s). Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. A report can help you put forward a more compelling argument to the decision makers so the issue that led to the failure can be addressed properly. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. 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. What type of drive would move the driven device at the same speed as the motor? Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. 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. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. Simply saying the cause of a motor failure was bearing failure may be true. 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. 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. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. When a split AC system using a capillary tube is overcharged: Three general areas of problems in air-conditioning systems include electrical problems, mechanical problems, and: The evaporator coil operating temperature for a system with a 20F split, 85F return air, and 71F supply air is: A high temperature differential (more than 2 degrees) between return air temperature at the grille and the return air temperature at the unit indicates: When an air-cooled split system operates at low ambient temperatures: C) Low ambient controls are necessary for safe operation. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. 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. Fault testing, motor failure can capacitively couple currents into the ground conductor be understood as asymmetrical signals in conductors... 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