open motor winding failures can be identified by
A common cause of an open winding is undersized lead lugs. Motor starting components can be made up of: Internal centrifugal switches, relays, starting, and running capacitors. In other words, there is a heavy spot somewhere on the rotor. If not, you might not get the most qualified team or best price. 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. 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. The machines provide the data. The failure mechanism involves the gradual development of a weakness in the insulation. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. Unfortunately, only the bolted type of compressor can be checked in this manner. runs a motor through its paces while its turned off. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. All photographs are copyrighted 1985-2019byEASA. It should concisely answer what, where, when, how and possibly why. That way your chosen solution doesnt just treat the symptom. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. In other words, the return current from the drive would be equal to the current to the drive. Whats the shops inventory of parts and materials for repairs? Skip to the next section on common causes of electric motor failure. 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? When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. 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. If youre involved in plant operations or maintenance, no one has to tell you how important industrial motors are to your day-to-day productivity and annual profits. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. (If youve had small children in your life, youll also have flashbacks.) Others will need more than five. This is the logical outcome, given what youve written in the rest of the report. Everyone is busy. 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. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. When the winding is energized, it forms magnetic poles. And fifth, use your motor shop to help you implement best practices for motor replacement, repair, storage and maintenance at your plant. Which organizations specify standards for electric motors? Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. We wrap it up by looking at the bigger picture, including how to perform a root cause failure analysis, 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. Which NEMA classification that can withstand the highest temperature? The stator is the stationary part of the motor. d. It flexes the humerus. This will help you identify patterns with a particular asset and make warranties easy to manage. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. 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. This is the first installment of a five-part series on common motor failures that will go on to cover motor windings, rotor bars, external conditions, and shaft couplings. Click to reveal Contamination. An open door switch on a gas furnace will cause: A) A complete system shutdown-no system operation at all. Start by completely disconnecting the spindle motor from all power sources. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. 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. Which of the following formulas can be used to calculate fan speed (RPM)? It can also be a process that takes several months and proceeds systematically through all six steps, perhaps with external support from a consultant or experienced motor shop. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. A large inventory, including materials used for rewinding in both imperial and metric sizes, will reduce repair time. a. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. More than one choice may apply. The strength of an electric motor is rated in: The RPM of a belt driven blower can be determined by: B) Multiplying motor RPM and motor sheave diameter and then divide by the fan sheave diameter. Chances are, you arent the final decision maker on larger operational and capital expenditures. Copyright 2016-2021 Duke Electric. 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. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. But wouldnt it be better to avoid failure in the first place? However, these tests only provide a "snapshot" of motor health. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. Insulation failures like this usually are caused by voltage surges. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Look on the outside of the motor for other potential problems, like holes or smoke points. 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. Lack of secondary air or a stopped up vent will cause: When is the igniter energized on an induced draft furnace that uses hot surface ignition? , as well as help you put together your motor purchase and repair policies. We can see your eyes rolling. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? 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. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. What is the first step in the operational sequence? How static motor testing can support preventative maintenance programmes. 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. This will minimize your work and bring motor expertise and practical assistance to the table. A) Setting the thermostat below room temperature. 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. 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. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Keep all of your organizations assets up and running without downtime. 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. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. 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. Motors are rated in either ________ or ________ operation. 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. Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. Uneven mass in motor windings and other wear-related factors. 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). Sigma currents are essentially stray currents that circulate in a system. Sounds simple. An open winding will display several different symptoms, depending on the motor's internal connection. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. 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