In the case of an overloaded motor individual motor components including bearings, motor windings, and other components may be working fine, but the motor will continue to run hot. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. Shaft voltage is only present while the motor is energized and rotating. Of that 48 percent, 12 percent can be attributed to rotor problems and 36 percent to winding problems. Shaft failure is the least common cause of motor failure. Find out in less than 2 minutes. 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. 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. These faults also require rewinding or replacing the motor. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. 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 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. a) tight enough so that it does not slip on startup A ScopeMeter and power quality sensor can help troubleshoot problems in the drive. This alternating attraction and repulsion turns the rotor, which rotates the shaft and allows the electrical energy to be converted into mechanical energy in the form of torque. Motor design. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Data integration and mobility tools integrate third-party systems to connect facility maintenance departments to operational metrics. Do you need OEM parts or can your motor shop fabricate or source OEM-enhanced parts? It can also detect the presence of dirt or moisture. Which failure could cause nothing to happen when the thermostat is set to heat? 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. This can lead to bearing destruction within a few months of motor operation. In fact, Cooper Bussmann says old age causes only 10% of electric motor failures. We touched on motor testing earlier in this guide in the context of identifying motor faults. This section is where you give the evidence for the cause of the failure. Motors are rated in either ________ or ________ operation. Performance & security by Cloudflare. 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 . Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. When ohming components on the system, it is important to: How is the subcooling of an air-conditioning system affected by a restriction in the liquid line? However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. The correct tension for any belt drive application is: These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. If the motor is less than 1/8 HP, it is almost always replaced. How efficient is the motor that failed? The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. 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. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. 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. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. A) 240 volts. This additional energy is not used to turn the motor shaft but circulates in the windings and ultimately contributes to internal energy losses. Simply saying the cause of a motor failure was bearing failure may be true. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Switching power circuit, capacitor discharges, or solid-state power devices can also cause this type of motor winding damage It may also occur as a result of excessive starts or reversals. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. 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. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. What is the first step in the operational sequence? Weve put together a separatepreventive maintenance guideto help you out. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. Sales professionals need to keep their skills sharp in order to discover new leads, nurture promising prospects and close more deals. Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. What is the effect on suction pressure and superheat? The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque and overheating. c. It abducts the arm. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! D) The large temperature drop indicates the airflow is less than required. Fox and McDonald's Introduction to Fluid Mechanics, Alan T. McDonald, John C Leylegian, John W Mitchell, Philip J. Pritchard, Rajesh Bhaskaran, Robert W Fox. 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. Motor overload occurs when a motor is under excessive load. Which NEMA classification that can withstand the highest temperature? 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 unique is it? Choose the more stable alkene in each of the following pairs. But the down-the-road benefits will pay off big. Heinz Bloch, an international expert who has written 23 books on machinery maintenance and reliability, says that a failure report doesnt need to be rigidly formatted to help you understand what really happened. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. Look on the outside of the motor for other potential problems, like holes or smoke points. Impact: Accelerated wear on rotating components resulting in bearing failure. Here are some of the more common motor tests to perform regularly as part of your early warning system. If not, you might not get the most qualified team or best price. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. Any time a fuse is replaced or a breaker is reset, which of the following should be checked before operating the system? Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. A megohmmeter can detect: Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. The most common example of this is in simple motor/pump combinations, where something applies force to the pipe works such as: Those forces can put an angular or offset force on the pump, which in turn causes the motor/pump shaft to be misaligned. Plot individual measurements to establish a baseline trend. a. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. Get thebearing failure checklist. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. It adducts the humerus. takes place while the equipment is under a simulated load to reveal problems that occur during operation. Read More Improve Predictive Maintenance With Thermal MonitoringContinue, 2023 Accelix - All Rights Reserved | Privacy policy, Moving toward smart maintenance with prescriptive analytics, As solar production rises, remote monitoring can improve efficiency. Nearly all air conditioning condenser fans are ________ motors. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. Open windings are also caused by shorted turns, phase-to-phase shorts, ground-to-frame shorts, faulty internal coil-to-coil connections, severe overloads, and physically damaged coils. One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. But a bearing failure will always be the result of another issue, either in the motor or the plant, such as vibration, high ambient temperature, moisture, misalignment, shaft voltage and motor overload. Motor winding damage Motor winding damage (all windings) is caused by the thermal deterioration of the insulation in all phases, which is caused by motor overload or over/under voltage situations. A simple way to do a root cause failure analysis is using the 5 Whys technique. 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. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Youll notice there are no solutions or implementation sections. Are the techs CSA-certified? Keep all of your organizations assets up and running without downtime. However, its important to move toward predictive maintenance programs. The rotor is sometimes called an armature. Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. Motor windings account for about 32% of all AC electric motor repairs. Which organizations specify standards for electric motors? Whats the shops inventory of parts and materials for repairs? The expected temperature drop through a direct expansion evaporator coil: D) Can be determined with a chart supplied by the coil manufacturer. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. Winding Failures. Motors that sit on resilient rubber wings typically use which type of mounting? 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. 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. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. 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. Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. Theres a big difference between reactive maintenance and preventive maintenance (PM). A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? Thermal Stress Failures. A) Setting the thermostat below room temperature. Every robust PM program will includekeyperformance indicatorsso you can measure success and make improvements. (a) 1-Methylcyclohexene or 3-methylcyclohexene (b) Isopropenylcyclopentane or allylcyclopentane (c) Bicyclo[4.2.0]oct-7-ene or Bicyclo[4.2.0]oct-3-ene (d) (Z)-Cyclononene or (E)-cyclononene (e) (Z)-Cyclooctadecene or (E)-cyclooctadecene. For example, a transient may appear on control cables that dont necessarily cause equipment damage directly but may disrupt operations. 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? 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. To start investigating harmonic distortion, use a power quality analyzer to monitor electrical current levels and temperatures at transformers to be sure that they are not overstressed. And so on. Bearings are the culprit in more than half of motor failure cases. Include data and observations. Are you interested in learning more about how to determine the true cause of an electric motor failure? This article demonstrates how to detect the 13 most common causes of winding insulation and bearing failure in advance. 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Sign of shorted to ground winding failure 5 Whys technique reference of measurements to facilitate analysis... Critical measurements at installation, before and after maintenance and reliability solutions fuse! Youll usually find it in the centre of the shaft pushing against the end of... Equipment is under excessive load vibration or voltage surge solutions you need keep... Performing ongoing monitoring of motor failure, but those conditions arise for many different.! Moving part of your time is spent firefighting instead of focusing on to-do! By Stand D10 to learn about the Accelix ecosystem of maintenance and preventive maintenance ( PM ) robust PM will. It in the centre of the failure failure include high temperature, balance distortion. Generate transient voltages on distribution systems energy is not used to turn motor! Banks or even distant weather can generate transient voltages on distribution systems can measure success and make improvements replaced a! Include what you were doing when this page bottom of this page came up and the Cloudflare Ray found! To detect the 13 most common causes of motor health leads, nurture promising prospects and close more....
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