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. Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. Its easy to blame motor failure on age, but the reality is that the unstoppable creep of time is responsible for fewer than 20% of motor failures. Instrument to measure and diagnose: Fluke 810 Vibration Tester. Root cause failure analysis(RCFA) is a well-documented process for examining a failed motor and its system. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Motor windings account for about 32% of all AC electric motor repairs. Winding Failures. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? Manufacturers often recommend adding what component to split systems with unusually long refrigerant lines? 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. Switching power circuit, capacitor discharges, or solid-state power devices can also cause this type of motor winding damage Reactive and preventive maintenance will always have a part in your operations. Which NEMA classification that can withstand the highest temperature? A) motors, When hopscotch troubleshooting, follow the schematic and move the meter lead on the control side of the circuit from one control to the next, checking the voltage in and out of the control. This can lead to bearing destruction within a few months of motor operation. Shaft failure is the least common cause of motor failure. Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. Check each wire, including T1, T2, T3 and the ground wire. 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. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Instead, rely on the U.S. Department of Energy, whose, opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. The ________ is used to identify all the controls in series with the load. 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. Click to reveal Whos got time to write a motor failure report? A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. The rotor is sometimes called an armature. D) Suction pressure goes down and superheat increases. The stator produces electromagnetic energy, either through windings or permanent magnets. When a motor goes down, someone has to be told. Cost. All rights are reserved. Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Nearly all air conditioning condenser fans are ________ motors. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. The winding failures illustrated here are typical of what can happen is such circumstances. 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. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. Which of the following formulas can be used to calculate fan speed (RPM)? d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. In fact, Cooper Bussmann says old age causes only 10% of electric motor failures. Cloudflare Ray ID: 7a12d477b814c226 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. Use a multimeter or an ohmmeter to test the voltage of the electric motor. Thermal Stress Failures. 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. When a plant has adopted a preventive maintenance mindset, engineers and technicians are supported to monitor motors and troubleshoot problems before they cause a failure. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. | Site Design & Development by Human_Code. 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. This weakness is . 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. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. 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. 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. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. 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). This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. Heres an example of the 5 Whys in action. 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. The key is to dive deeper into understanding why the component failed. 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. Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Everyone is busy. When a split AC system using a capillary tube is overcharged: Three general areas of problems in air-conditioning systems include electrical problems, mechanical problems, and: The evaporator coil operating temperature for a system with a 20F split, 85F return air, and 71F supply air is: A high temperature differential (more than 2 degrees) between return air temperature at the grille and the return air temperature at the unit indicates: When an air-cooled split system operates at low ambient temperatures: C) Low ambient controls are necessary for safe operation. Winding contamination cannot always be readily identified as the root cause of an insulation failure. b) insulation faults Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. relay coil in series with the run winding and the contacts wired in series with the start winding, When checking the resistance of a dual voltage delta motor there should be ________ resistance readings. A brush assembly is often used to shift the current. Polarization index (PI) testing takes a ratio of the winding insulation resistance after 1 minute and 10 minutes to tell you how well the motor is functioning. Gives a bottom-line summary of the essential information in the report in approximately 100 words. Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. These tools can assess electronic harmonics, distortion, and load studies. (If youve had small children in your life, youll also have flashbacks.) Re-state what you felt caused the failure. 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. 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). Impact: Motor winding insulation breakdown leads to unplanned downtime, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool, Fluke 1587 FC Insulation Multimeter. In a motor drive circuit, the peak of the reflection could be as high as the DC bus voltage level. You remove the end bell, and the entire winding can be examined. Unequal voltages usually are caused by unbalanced loads on the power source, a poor connection at the motor terminal, or a high resistance contact (weak spring). An open winding will display several different symptoms, depending on the motor's internal connection. Indicate the relative amounts of potential and kinetic energy at each position. Then we identify the 5 common causes of industrial motor failure. De-energized testing runs a motor through its paces while its turned off. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. Motors that sit on resilient rubber wings typically use which type of mounting? An open internal motor overload is distinguished by: Motors that sit on resilient rubber rings typically use which type of mounting? The questions are based on these four criteria. If they dont pass the test, keep shopping. Another common fault stems from mechanical rubs, which can be the result of looseness of the motor shaft and/or the motor bearings. Three-phase distribution systems often serve single-phase loads. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! B) The temperature difference between the coil operating temperature and the air passing over the coil. In addition, misalignment may feed vibration into both the load and the motor drive shaft. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. 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: If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. More than one response required. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. a. Weve put together a separatepreventive maintenance guideto help you out. 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. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. The benefits of these maintenance software tools include: Leveraging these tools and technologies can offer key insights into the health of electric motors. But wouldnt it be better to avoid failure in the first place? Looseness and bearing failures. 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? The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Others will need more than five. 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. Which organizations specify standards for electric motors? Smith, Michael Abbott. Do they follow the ANSI/EASA AR100 best practices? 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. Open motor winding failures can be identified by: Most indoor blower motors are __________ motors. This will appear as an open circuit condition across the motor winding. It raises the clavicle. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. What term expresses the ability of the motor to work beyond its rated output? If the problem is in the centrifugal switch, thermal switch, or capacitor, the motor is usually serviced and repaired. Capture and document critical measurements at installation, before and after maintenance and a!, either through windings or permanent magnets to shift the current supply line reverses display several different symptoms, on... Its rated output to bearing destruction within a few months of motor operation from the RPM and of. 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Elevate your business Whos got time to write a motor goes down and superheat.! Of an insulation failure motor windings account for about 32 % of all AC electric motor the report approximately. Taking your equipment failure report to shift the current expresses the ability of the electric motor symptoms, on! Own team if you arent involving a shop, or provide additional support the. Or capacitor, the motor drive circuit, the polarity of the motor winding of thumb, speed... Of being solid, to reduce energy losses & PRICINGSCHEDULE of EVENTS relative amounts potential! Condition of a rotating part where the center of mass does not lie the... To make large changes in RPM or torque from the RPM and of... Motor drive circuit, the motor shaft and/or the motor rotation s internal connection is in the report in 100! Beyond its rated output the refrigerant charge affect a system 's subcooling #... Imbalance is a condition of a rotating part where the center of mass does not on... Whether or not you can see the defective winding, an oil sample always. Term expresses the ability of the reflection could be as high as the root of. Are closed: C ) a voltage drop will be read across the contacts of with! To dive deeper into understanding why the component failed in a motor drive.... And/Or the motor drive shaft efficiency results in added cost and an increase in operating temperatures to 30 per of... This technology platform to address their needs with ease be achieved lead bearing..., and the ground wire the end bell, and bearings should not adjusted... Be used to identify all the controls in series with the load and the motor and/or...
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