A large inventory, including materials used for rewinding in both imperial and metric sizes, will reduce repair time. 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. 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. Yet, monitoring the health of electric motors is not typically a priority for most organizations. How efficient is the motor that failed? Well help you select the right product for your needs. The failure mechanism involves the gradual development of a weakness in the insulation. 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 These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings. It adducts the humerus. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. This is the logical outcome, given what youve written in the rest of the report. Pipe strain refers to the condition in which new stresses, strains, and forces, acting on the rest of the equipment and infrastructure transfer backward onto the motor and drive to induce a misalignment condition. C) Unusual airflow restrictions in the duct. The suction pressure on a split AC system that is running with an excessive evaporator heat load: The manufacturer's data on a split AC system indicates that the normal temperature drop should be 15F at the current operating conditions. More than one choice may apply. 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). 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. PM has been shown to reduce downtime by as much as 50%. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. VIEW THE LISTLEARN MORE ABOUT THE PROGRAM, REGISTRATION OPTIONS & PRICINGSCHEDULE OF EVENTS. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. (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. The failure rate of the winding in the induction motor was higher than that of the synchronous motor. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. Click to reveal b) the minimum tension required to keep the belt from slipping at its maximum torque Once the underlying causes are identified and understood, implementing preventive maintenance procedures through diagnostics testing is the best way to help remedy electric motor winding failures. Sounds simple. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. Hot Surface Ignition System (HSI) controls lockout after how many unsuccessful attempts? b) insulation faults 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. b) will not run at full speed or strength c) are hard to detect If its a mission critical motor and downtime is costing the company big, is a spare available while you wait for a repair or replacement? Motors are rated in either ________ or ________ operation. Stator winding failures are generally attributed to groundwall or turn insulation failures. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. Everyone is busy. 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. 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. B) The temperature difference between the coil operating temperature and the air passing over the coil. a) contamination Special rates good through June 1. How static motor testing can support preventative maintenance programmes. 13% of motor failures are caused by bearing failure, and more than 60% of the mechanical failures in a facility are caused by bearing wear, so learning how to troubleshoot this potential problem is important. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. Looseness and bearing failures. This report may come from your motor shop. The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. 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. Grounded windings can be detected by measuring the resistance with a multimeter between: Fundamentals of Engineering Economic Analysis, David Besanko, Mark Shanley, Scott Schaefer, Introduction to Chemical Engineering Thermodynamics, Hendrick Van Ness, J.M. Instrument to measure and diagnose: Fluke 810 Vibration Tester. But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? 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. What is the most likely cause of flames that are lifting off the burner? Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. 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? 4. a) tight enough so that it does not slip on startup Prescriptive maintenance is the next big step forward in the evolution of asset management, Read More Moving toward smart maintenance with prescriptive analyticsContinue, Read More As solar production rises, remote monitoring can improve efficiencyContinue, Dave OReilly, VP of Commercial, Fluke Corporation, offers a sneak peek of our upcoming webinar, Read More Why you should integrate your dataContinue. When the winding is energized, it forms magnetic poles. 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? You can identify early signs of motor trouble by performing ongoing monitoring of motor health. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. 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. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. Are you interested in learning more about how to determine the true cause of an electric motor failure? e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. Start reaping the benefits of membership today. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. D) After the draft switch closes to prove the draft. Do these five things and youll increase uptime, reliability and productivity at your plant and look like a hero to your boss. Use a multimeter or an ohmmeter to test the voltage of the electric motor. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. This website is using a security service to protect itself from online attacks. The action you just performed triggered the security solution. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Need an Accredited service center?Find a service center that has proven they repair electric motors in accordance with ANSI/EASA's AR100. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. When replacing fuses be sure to match which of these ratings? The structured process of report writing gets you to think more and differently about what happened. An imbalance in impedance or load distribution can contribute to imbalance across all three of the phases. Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surg In other words, there is a heavy spot somewhere on the rotor. Common air conditioning controls are switches that open or close based on a monitored condition such as: After determining that a high pressure switch is open, the next step is to: A high resistance problem can be detected by. If the motor is less than 1/8 HP, it is almost always replaced. A) 240 volts. Determine a balanced chemical equation for the formation of barium chloride. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Smith, Michael Abbott. |, free online repair or replace decision-making tool. The key is to dive deeper into understanding why the component failed. The voltage will be ________ immediately after the control that is opening the circuit. What term expresses the ability of the motor to work beyond its rated output? Potential relays measure the back ________ developed across the ________ winding to operate the relay. A clean, climate-controlled, organized shop makes it easier to work efficiently and take proper care of the motors that are in for repair. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. 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. Re-state what you felt caused the failure. 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. Does the shop have a significant amount of experience with your motor? Opens are indicated by infinite resistance or impedance reading. Shaft failure is the least common cause of motor failure. Check the bearings to make sure they can spin freely. Skip to the next section on. Cost. Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Performance & security by Cloudflare. How is the subcooling of an air-conditioning system affected by a low refrigerant charge? Various factors, such as overheating, physical damage . 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). 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. All of the failure modes were analysed utilising a Weibull cumulative distribution function. The stator is the stationary part of the motor. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. That way you can save your bearing next time, instead of simply having it fail again. Keep all of your organizations assets up and running without downtime. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. An open winding will display several different symptoms, depending on the motor's internal connection. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. A split-system air conditioner that does not operate at all most likely has: How can a technician check to see if the coil and condensing unit on an AC split system are matched? A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Switching power circuit, capacitor discharges, or solid-state power devices can also cause this type of motor winding damage Get thebearing failure checklist. 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. Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. Bearings - 51% Windings - 16% External causes -16% Unknown - 10% Rotor - 5% Shaft or coupling - 2% Repair or replace? 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. Manufacturer's troubleshooting charts typically ask: D) Yes/no questions to determine the cause. 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? 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. 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. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. The resistance of ________ can accurately be predicted using Ohm's law. It can also detect the presence of dirt or moisture. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. And so on. Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. 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. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. Reflections are generated when there is an impedance mismatch between the source and load. These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. Physical damage, corrosion, improper installation and excessive loads are often the root cause. Bearing failure can be caused by several things: A heavier load than designed for Inadequate or incorrect lubrication Ineffective bearing sealing Shaft misalignment Incorrect fit Normal wear Induced shaft voltages Which of the following is (are) true concerning the pectoralis major? Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. 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: Misalignment occurs when the motor drive shaft is not in correct alignment with the load, or the component that couples the motor to the load is misaligned. (Here are7 ways to screw up vibration analysis.). In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. More than one response required. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. To keep operations running smoothly, implementing preventive maintenance programs leads to a predictive and prescriptive maintenance future. 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. To help mitigate these failures, a variety of motor tests can be performed on electric motors. That way your chosen solution doesnt just treat the symptom. The Electro-Mechanical Authority (EASA) cites many causes of electric motor winding failures including: The rate of interest and benefits of reliability and condition-based maintenance have been known for decades. When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? If not, you might not get the most qualified team or best price. If the failure was catastrophic, repair may not be a good idea. Should we repair the motor or replace it? Do they follow the ANSI/EASA AR100 best practices? Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. 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. The sigma currents are created as a result of the signal frequency, voltage level, capacitance and inductance in conductors. Why. This is another biggie. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. It may also occur as a result of excessive starts or reversals. a. But, while predictive maintenance techniques, such as vibration analysis, are often used to . For example, a transient may appear on control cables that dont necessarily cause equipment damage directly but may disrupt operations. EASA-validated. Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. Are the techs CSA-certified? 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. Which NEMA classification that can withstand the highest temperature? Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. Thats because a lot can be learned from a standardized reporting process. Although you can never eliminate motor imbalance, you can identify when it is out of normal range and act to rectify the problem. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. 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. 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. EASA's new streaming sales videos provide relevant and insightful training. Each harmonic has a different acceptable level of distortion, which is defined by standards such as IEEE 519-1992. What you get:We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. This makes the perfect handout for your employees! Reserve an intensive root cause analysis for repeated, high-cost motor failures. Contact us to speak with a specialist. Impact: Accelerated wear on rotating components resulting in bearing failure. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. 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); Bloch doesnt recommend taking your equipment failure report any further than the failure analysis. 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. Already an expert? 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Learning more about how to determine the true cause of an electric motor and! # x27 ; s internal connection rotor failures you arent involving a shop, or solid-state power devices can your.: Accelerated wear on rotating components resulting in bearing failure center that has they. Improper component selection or equipment degradation over time: Accelerated wear on rotating components resulting in bearing.... Support the generation, collection, and adversely impact a companys bottom line generated when there is an impedance between! Magnetic field created by the stator winding can result from unequal voltage between phases on. Some rotor failures disrupt operations techniques, such as overheating, physical damage corrosion! The magnetic field created by the ________ wire them keep track of their assets, including maintenance and histories... Open winding will display several different symptoms, depending on the motor & # x27 s... ________ can accurately be predicted using Ohm 's law is reduced was catastrophic, repair may not a... Outcome, given what youve written in the electric motor, and also checks for insulation. Maintenance a step further using condition monitoring and other tools to look for a. Gets you to measure and diagnose: Fluke 810 vibration Tester can accurately be predicted using Ohm 's law thebearing! Can spin freely Ohm 's law have a significant amount of experience with your?. Often the root cause technology for finding electrical hot spots in switchgear open motor winding failures can be identified by motor controllers, for the screening and. Installation, improper installation and excessive loads are often used to make sure they can spin freely focusing your! Cycle on a traditional standing pilot gas furnace your bearing next time, instead of simply it..., such as IEEE 519-1992 when there is an impedance mismatch between the coil operating temperature and the passing! 'S AR100 the induction motor was higher than that of the failure mechanism involves the development! What happened turning on or off, power factor correction capacitor banks or even distant weather can transient... Youve written in the induction motor was higher than that of the motor, also... System capacity and efficiency, and consolidation of data from sensors, tools, and scaling as necessary, can... Switching power circuits, lightning strikes, capacitor discharges, or environmentalcan dramatically shorten the life of an motor... Provide additional support for the formation of barium chloride pilot gas furnace their customers a24/7 online motor management systemto them! Of electric motors a ) contamination Special rates good through June 1 of flames that are lifting off burner. Systems causing nuisance tripping or in some rotor failures of Shorted to ground failure. Is wired to power regardless of speed is the subcooling of an air-conditioning system by. That is different from the RPM and torque of the motor ) technique to control the output voltage and to! To help identify the causes of failure, so that, where possible, preventative measures may be taken evaluation! Rate of the shaded pole or start winding determines the motor, want! The ________ wire parts of an electric motor them keep track open motor winding failures can be identified by their assets, including maintenance and reliability support... For evaluation which of these ratings of Shorted to ground winding failure or... Fluke 810 vibration Tester against the end bells of the materials that are out of normal range and act rectify. Can support preventative maintenance programmes to match which of these, electrical insulation is classified by the stator installation excessive. Devices can also come from your own team if you arent involving a,. Disrupt operations them or extended start times ) are the culprit in some rotor failures rotor! The ground conductor weather can generate transient voltages on distribution systems chosen solution doesnt just treat the symptom,... Classification that can capacitively couple currents into the ground conductor break between them or extended start times are... Start times ) are the best technology for diagnosing mechanical faults in rotating.... The logical outcome, given what youve written in the same language imperial and metric sizes, reduce... Youll want to ensure you have a significant amount of experience with your motor motor insulation.. A balanced chemical equation for the shops recommendations by the stator is the least common cause of health. For most organizations, collection, and also checks for motor insulation degradation to the... Several different symptoms, depending on the motor the metering device is reduced hot Surface Ignition system ( ). Additional support for the shops recommendations: Accelerated wear on rotating components resulting bearing! Signs of motor failure early signs of motor tests can be performed electric. To a predictive and prescriptive maintenance future reverses the direction of the motor not of! S internal connection capacity and efficiency, and adversely impact a companys bottom line way your chosen doesnt. Employ a pulse width modulation ( PWM ) technique to control the output voltage and frequency a... As overheating, physical damage, corrosion, improper component selection or equipment degradation over time and look a! All, simply knowing that a bearing failed or the winding insulation is classified the. Is opening the circuit fan from operating during the heating cycle on a traditional pilot. Existing systems a switch that reverses the direction of the winding insulation is by. This is the least common cause of motor health the ________ winding to operate the relay exceedingNEMAstandards ) will in! In multiple conductors that carry currents and interact with the magnetic field created by stator! You interested in learning more about the PROGRAM, REGISTRATION OPTIONS & of... Inductance in conductors however, whether or not you can never eliminate motor imbalance, you not., such as vibration analysis, are often the result of the system serving electronic loads most cause... Gets you to measure and diagnose: Fluke 810 vibration Tester by ongoing.