The stator is the stationary part of the motor. Transient voltages can come from several sources either inside or outside of the plant. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. Once acid is identified in Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. The key is to dive deeper into understanding why the component failed. Does the shop have a significant amount of experience with your motor? Sounds simple. Performance & security by Cloudflare. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. In the motor if winding is open 33% Stator can induce more current causes winding failure, for creation of vibration rotor winding can fail. Contamination. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. The expected temperature drop through a direct expansion evaporator coil: D) Can be determined with a chart supplied by the coil manufacturer. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. 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. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. This is another biggie. a) will draw higher than normal amps Winding contamination cannot always be readily identified as the root cause of an insulation failure. What term expresses the ability of the motor to work beyond its rated output? However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. Special rates good through June 1. Gives a bottom-line summary of the essential information in the report in approximately 100 words. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. 23% Major winding failure [8], 2011 c) Under voltage and Over voltage Motors are used everywhere in industrial environments and they are becoming increasingly complex and technical, sometimes making it a challenge to keep them running at peak performance. A policy will streamline processes, reduce decision-making time and increase confidence that your conclusions consider all angles of the repair or replace question, including risk, opportunity and costs. In this case, different is better. Soft foot is often manifested between two diagonally positioned mounting bolts, like the way that an uneven chair or table tends to rock in a diagonal direction. Yet determining the cause is a critical step in protecting your motors. 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. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? 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. Which NEMA classification that can withstand the highest temperature? 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. 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. Here is a list of the common winding problems found in an electric motor: Shorted to ground winding failure. 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. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. All rights are reserved. Possible solution: It is critical that the motor is kept as cool as possible, ensuring the operating environment is kept cool if possible will help prevent breakdowns. Your IP: near the wall? 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? When the winding is energized, it forms magnetic poles. De-energized testing runs a motor through its paces while its turned off. The correct tension for any belt drive application is: Well help you select the right product for your needs. A) International Electrotechnical Commission (IEC). A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. 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. (If youve had small children in your life, youll also have flashbacks.) Youll notice there are no solutions or implementation sections. Reactive and preventive maintenance will always have a part in your operations. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Contact us to speak with a specialist. 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. and preventive maintenance (PM). Heres how a motor failure report can help with motor management. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. How long have the staff been there? If writing the odd report meant you could spend more of your time getting sh*t done instead of fixing stuff that broke when it wasnt supposed to, would you be willing to give it a try? Bearings are the culprit in more than half of motor failure cases. But, while predictive maintenance techniques, such as vibration analysis, are often used to . It is found that one isotope is more concentrated near the axis of rotation of the chamber and the other is more concentrated near the cylindrical wall of the chamber. Whats the shops inventory of parts and materials for repairs? This website is using a security service to protect itself from online attacks. More than one choice may apply. Use a multimeter or an ohmmeter to test the voltage of the electric motor. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. 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. 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? This is the logical outcome, given what youve written in the rest of the report. PM has been shown to reduce downtime by as much as 50%. 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 . Heres how to set your motors up for success, not failure. Nearly all air conditioning condenser fans are ________ motors. We touched on motor testing earlier in this guide in the context of identifying motor faults. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Whats the lead time on a new motor? Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? That way your chosen solution doesnt just treat the symptom. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. For this reason, it makes sense to begin your troubleshooting by checking for motor overload. Weve spent most of this guide talking about what to do when a motor fails. Bearing failure is an expensive problem both in terms of motor repair and downtime, so helping to prevent this by measuring shaft voltage and bearing current is an important diagnostic step. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. But it wont help you prevent it in the future. 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. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. For example, a transient may appear on control cables that dont necessarily cause equipment damage directly but may disrupt operations. This can lead to bearing destruction within a few months of motor operation. Simply saying the cause of a motor failure was bearing failure may be true. to ask deciding whether to repair or replace your electric motor. But wouldnt it be better to avoid failure in the first place? 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. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. A few methods can detect such issues, including, for one, surge-partial-discharge testing, during which investigators look for the repetitive partial-discharge inception voltage (RPDIV) and repetitive partial-discharge extinction voltage (RPDEV), and impulse value in millivolts (mV). 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. What is their internal quality management system and how do they make sure theyre following it? Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. Most indoor blower motors are ________ motors. 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