Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. Once acid is identified in 1 in 10 failures are mysterious. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. Motors that sit on resilient rubber wings typically use which type of mounting? Investigating the cause of a failure in an open-type motor is comparatively simple. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? The structured process of report writing gets you to think more and differently about what happened. d. It flexes the humerus. Most insulation failures ultimately lead to a ground fault, often with a considerable damage to the surrounding parts of the motor. Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. and preventive maintenance (PM). Electrical failures disrupt the power supply to the motor. Special rates good through June 1. This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. c) moisture 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 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. And so on. The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Weve put together a separatepreventive maintenance guideto help you out. Reproduction of these photographs by print or electronic means is prohibited. 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 . Monitoring has two components: inspection and testing. 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. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. Plot individual measurements to establish a baseline trend. 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. Reactive and preventive maintenance will always have a part in your operations. a) contamination Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. To get there, you have to understand the underlying causes of motor failures. A) 240 volts. c. It abducts the arm. 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. A) International Electrotechnical Commission (IEC). 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: Foreign bodies which find their way inside the motor can dent bearing . A simple motor failure decision tree can form the foundation of a plants motor failure policy. Open windings are also caused by shorted turns, phase-tophase shorts, ground-to-frame shorts, faulty internal coil-tocoil connections, severe overloads, and physically damaged coils. Start reaping the benefits of membership today. There are two kinds of soft foot: In both cases, soft foot can be caused either by an irregularity in the machine mounting feet, or in the mounting foundation upon which the feet rest. 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. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. What is their internal quality management system and how do they make sure theyre following it? The voltage will be ________ immediately after the control that is opening the circuit. Yes, itll require some upfront work. Know the breakpoints at which youre willing to repair vs. replace. How efficient is the motor that failed? 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. 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. Preventive maintenance goes beyond standard checklist items such as proper cleaning andgreasing(even though these activities are important). In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. Indicate the relative amounts of potential and kinetic energy at each position. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. Heres an example of the 5 Whys in action. 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. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. b. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. Get thebearing failure checklist. 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? Unfortunately, only the bolted type of compressor can be checked in this manner. Yet determining the cause is a critical step in protecting your motors. 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. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. 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. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. The key is to dive deeper into understanding why the component failed. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. Arming maintenance engineers and technicians with the right knowledge, prioritizing workload and managing preventative maintenance to monitor equipment and troubleshoot intermittent, elusive problems can, in some cases, avoid failures due to normal system operating stresses and reduce overall downtime costs. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Some motor failures will require asking fewer than five whys. 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. The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. Sigma currents are essentially stray currents that circulate in a system. Physical damage, corrosion, improper installation and excessive loads are often the root cause. How many years of experience do they have? Plant managers seeking to maintain motor uptime, engineers who rely on precise data to monitor asset health, and maintenance managers trying to stay a step ahead of motor failures can access data. Motors are rated in either ________ or _________ operation. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Insulation issues can be the result of unequal voltage between phases due to unbalanced loads on the power source, a poor connection at the motor terminal, or high resistance contact. Always ensure the motor thermal protector has not opened. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. 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. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. Sounds simple. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. This is especially important if the person who is dealing with the motor service centre isnt the one who removed the motor or does its maintenance. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. Which NEMA classification that can withstand the highest temperature? Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. 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. 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? What is the first step in the operational sequence? 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. b) will not run at full speed or strength This will help you identify patterns with a particular asset and make warranties easy to manage. near the wall? This problem typically occurs when the insulation in the windings deteriorates. runs a motor through its paces while its turned off. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. Having a motor failure policy will help your team make proactive decisions, including procuring services and equipment ahead of time. Others will need more than five. 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. Explain why a sample of iron(III) sulfate is uncharged. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. 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. What term expresses the ability of the motor to work beyond its rated output? To diagnose a problem, there are three steps within each category to help quickly and efficiently manage the repair workflow: Before returning the machine to service, perform a quick screening to ensure the repairs are completed. Which organizations specify standards for electric motors? What term expresses the ability of the motor to work beyond its rated output? 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. 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). Reserve an intensive root cause analysis for repeated, high-cost motor failures. This is another biggie. (Note: almost all misalignment is compound misalignment, but practitioners talk about misalignment as the two separate types because it is easier to correct a misalignment by addressing the angular and parallel components separately.). This is another biggie. Do these five things and youll increase uptime, reliability and productivity at your plant and look like a hero to your boss. Infrared sensors can seamlessly integrate with a software platform that gathers data from many other sensor types. 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. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Terms and ConditionsCopyright 2016-2021 Duke Electric. If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. If its an older motor, can you find a new motor that will fit in the old spot, given that new motors tend to be smaller than an equivalent motor made 25-plus years ago? 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. Sales professionals need to keep their skills sharp in order to discover new leads, nurture promising prospects and close more deals. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. 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