This is another biggie. a) will draw higher than normal amps How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. Opens are indicated by infinite resistance or impedance reading. Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. 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. Copyright 2016-2021 Duke Electric. Extent of failure. Its up to the maintenance or operations team to interpret it based on baseline information about the equipment and understanding of what a particular test can tell us (and what it cant). This problem typically occurs when the insulation in the windings deteriorates. Sounds simple. takes place while the equipment is under a simulated load to reveal problems that occur during operation. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. c) moisture This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. Open motor winding failures can be identified by: A) Zero resistance reading B) Infinite resistance reading C) Measurable resistance reading D) All of the above B) Infinite resistance reading Motor starting components can be made up of: A) Starting and running capacitors only B) Internal and external centrifugal switches only c. It abducts the arm. It should concisely answer what, where, when, how and possibly why. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. 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. If the motor is less than 1/8 HP, it is almost always replaced. 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 other words, there is a heavy spot somewhere on the rotor. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. In addition, misalignment may feed vibration into both the load and the motor drive shaft. A) Adding refrigerant increases the system subcooling. If the failure was catastrophic, repair may not be a good idea. Include data and observations. 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? They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. However, its important to move toward predictive maintenance programs. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. Winding Failures. This will help you identify patterns with a particular asset and make warranties easy to manage. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque and overheating. 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. (Here are7 ways to screw up vibration analysis.). Charred connections in the motor's connection (terminal) box are a sure indication of this problem. 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. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Infrared sensors can seamlessly integrate with a software platform that gathers data from many other sensor types. EASA-validated. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. Shaft voltage is only present while the motor is energized and rotating. 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. 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? 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. Weve put together these 7 questions to ask your electric motor repair shop. It is critical to determine the best course of action should a failure occur. 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? What is the first step in the operational sequence? Weve spent most of this guide talking about what to do when a motor fails. 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. Whats the lead time on a new motor? Contact us to speak with a specialist. Whos got time to write a motor failure report? Each harmonic has a different acceptable level of distortion, which is defined by standards such as IEEE 519-1992. Before diagnosing the problem as a failed compressor, always allow the motor protector time to reset, usually until the upper housing is within 5F of ambient temperature (this can vary by unit); [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. Check each wire, including T1, T2, T3 and the ground wire. Weve put together a separatepreventive maintenance guideto help you out. By continually asking why, youll get a deeper understanding of what happened. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Why. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. PM has been shown to reduce downtime by as much as 50%. And those issues will have another cause. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. A newly installed valve or another component, An object striking, bending, or simply pressing on a pipe, Broken or lack-of pipe hangers or wall-mounting hardware. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. Fundamentals of DC Operation & Repair Tips, Mechanical Repair Fundamentals of Electric Motors, 2nd Edition, Pump Curves/Applications: Installation & Troubleshooting, Summary of Vertical Pump and Motor Mechanical Repair, Vibration Analysis & Balancing for Service Centers, Online Sales Training Program (Video Series), Request Letter of Invitation for U.S. Visa, Getting the Most from Your Electric Motors. In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. (If youve had small children in your life, youll also have flashbacks.) 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. Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. Equipment failure can result in high monetary losses both from potential motor, or parts, replacement and from equipment downtime for the system the motor powers. Get thebearing failure checklist. Keep all of your organizations assets up and running without downtime. Your motor shop can help you. 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. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. A megohmmeter can detect: Choose the more stable alkene in each of the following pairs. The life of a three-phase stator winding can be shortened dramatically when the motor is exposed to unfavorable operating conditions electrical, mechanical or environmental. Various factors, such as overheating, physical damage . Often these mechanical faults are related: shaft imbalance, looseness, or misalignment left uncorrected will cause increased forces on the bearings which leads to rapid wear of the bearings. Three-phase distribution systems often serve single-phase loads. Theres a big difference between reactive maintenance and preventive maintenance (PM). Which of the following is (are) true concerning the pectoralis major? Most indoor blower motors are ________ motors. 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. Winding shorted turn-to-turn 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. It may also occur as a result of excessive starts or reversals. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. Find out in less than 2 minutes. 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. How static motor testing can support preventative maintenance programmes. Others will need more than five. 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. Which of the following formulas can be used to calculate fan speed (RPM)? Stator winding failures are generally attributed to groundwall or turn insulation failures. An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? 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. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. Motor overload occurs when a motor is under excessive load. Already an expert? There a few types of misalignment: Impact: Premature wear in mechanical drive components that leads to premature failures, Instrument to measure and diagnose: Fluke 810 Vibration Tester, Fluke 830 Laser Shaft Alignment Tool. 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? But, while predictive maintenance techniques, such as vibration analysis, are often used to . When an electric motor fails, theres one question that must be answered. This section is where you give the evidence for the cause of the failure. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. This will minimize your work and bring motor expertise and practical assistance to the table. Thermal deterioration of insulation in one phase of the stator winding. Transient voltages can come from several sources either inside or outside of the plant. Special rates good through June 1. 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. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Motor windings account for about 32% of all AC electric motor repairs. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. That way, action can be taken before its too late. Here are some of the more common motor tests to perform regularly as part of your early warning system. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. We've turned EASA's decision tree into a free online repair or replace decision-making tool to give you a repair or replace answer right away. You remove the end bell, and the entire winding can be examined. And so on. Cloudflare Ray ID: 7a12d477b814c226 d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. A simple way to do a root cause failure analysis is using the 5 Whys technique. Explain why a sample of iron(III) sulfate is uncharged. 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.

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