Skip to the next section on common causes of electric motor failure. Having a motor failure policy will help your team make proactive decisions, including procuring services and equipment ahead of time. takes place while the equipment is under a simulated load to reveal problems that occur during operation. runs a motor through its paces while its turned off. Even with a flexible coupling, a misaligned shaft will transmit damaging cyclical forces along the shaft and into the motor, leading to excess wear on the motor and increasing the apparent mechanical load. Motor design. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. Shaft voltage is only present while the motor is energized and rotating. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Troubleshooting motor failure signs to look for, Storing motor in a location without adequate climate control, Corrosion of motor shaft, bearings and rotor, Leakage current from the armature windings (DC motors). 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. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. In other words, the return current from the drive would be equal to the current to the drive. This will appear as an open circuit condition across the motor winding. Explain why a sample of iron(III) sulfate is uncharged. 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. 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. That doesnt mean humans are off the hook, however. [12], 2012 b) Reverse Phase sequence fault In three phases when two phases of supply line reverses. 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. 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? Which failure could cause nothing to happen when the thermostat is set to heat? Temperature plays a major role in motor failure. A tri-fold brochure containing the information on this page is available for purchase. The ________ is used to identify all the controls in series with the load. Then we identify the 5 common causes of industrial motor failure. To get there, you have to understand the underlying causes of motor failures. Already an expert? 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. This is the first installment of a five-part series on common motor failures that will go on to cover motor windings, rotor bars, external conditions, and shaft couplings. Arming maintenance engineers and technicians with the right knowledge, prioritizing workload and managing preventative maintenance to monitor equipment and troubleshoot intermittent, elusive problems can, in some cases, avoid failures due to normal system operating stresses and reduce overall downtime costs. Transient voltages can come from several sources either inside or outside of the plant. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Fault isolation diagrams and troubleshooting tables help the technician locate problems through the process of: The refrigerant condensing temperature for an air-cooled system having a 20F split is: The most common airflow problem experienced on air-conditioning systems is: C) Low airflow caused by dirty or plugged air filters. All rights are reserved. 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. Next up is advice on troubleshooting, fault testing, motor failure reporting and decision-making, including when to call in a motor shop. Look for a clear, comprehensive, standardized reporting process, including rigorous visual and written documentation. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. 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 makes the perfect handout for your employees! Include data and observations. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. A) Fan RPM = Motor RPM Motor Sheave Diameter Fan Sheave Diameter. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. Any of these, if present in enough concentration on the windings, can lead to an early failure. 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. Terms and ConditionsCopyright 2016-2021 Duke Electric. To help mitigate these failures, a variety of motor tests can be performed on electric motors. , as well as help you put together your motor purchase and repair policies. Foreign bodies which find their way inside the motor can dent bearing . 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. . Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. For decades, plant personnel have performed insulation resistance tests with handheld megohmmeters to prevent motor failures that lead to costly unplanned shutdowns, failure-to-produce penalties and rewinding repairs. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Contamination. There could also be thermal deterioration in all phases of the stator winding typically due to load demands exceeding the rating of the motor or by very high currents in the stator winding due to a locked rotor. Keep all of your organizations assets up and running without downtime. It may also occur as a result of excessive starts or reversals. If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. 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. Thats why its so important to get to the root cause of a failure. Others will need more than five. 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. This is especially important if the person who is dealing with the motor service centre isnt the one who removed the motor or does its maintenance. The benefits of detecting, identifying, and evaluating electric motor abnormalities are decreased motor failures and less unexpected downtime. This can lead to bearing destruction within a few months of motor operation. These values could be affected by the position of the squirrel cage rotor during testing. Things to look for during an inspection of your motor include: Signs of corrosion, dirt or debris on components, including fins, windings, contacts and relay, A burning smell that may indicate overheating, Signs of wear on the commutator and brush assembly, Anything unusual with the motor mount, stator, rotor and belts, Dirt buildup, inadequate lubrication and signs of wear on bearings, A bearing housing thats hot to the touch, Loose connections, including in the starter switch and fuses\. Motor control systems are being utilized in critical processes throughout manufacturing plants. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? Know the breakpoints at which youre willing to repair vs. replace. In addition, misalignment may feed vibration into both the load and the motor drive shaft. quent compressor failure can result within a few hours. a. Its responsible for 51% of motor failures. Start reaping the benefits of membership today. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Once acid is identified in This will help you identify patterns with a particular asset and make warranties easy to manage. Check each wire, including T1, T2, T3 and the ground wire. Sigma current can also be understood as asymmetrical signals in multiple conductors that can capacitively couple currents into the ground conductor. Will the shop do the work themselves, or will they outsource it? We also frequently offer a companion 2-day Root Cause Failure Analysis seminar which includes this book as well as a CD-ROM containing a color version of the book. 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. Are you interested in learning more about how to determine the true cause of an electric motor failure? Thermal deterioration of insulation in one phase of the stator winding. Already an expert? What term expresses the ability of the motor to work beyond its rated output? Are the techs CSA-certified? More than one response required. When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? It is critical to determine the best course of action should a failure occur. 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. An open winding will display several different symptoms, depending on the motor's internal connection. 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). But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? Switching power circuit, capacitor discharges, or solid-state power devices can also cause this type of motor winding damage Whats the shops inventory of parts and materials for repairs? 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). A) Setting the thermostat below room temperature. (If youve had small children in your life, youll also have flashbacks.) 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. What is the most likely cause of flames that are lifting off the burner? Choose the more stable alkene in each of the following pairs. Monitoring has two components: inspection and testing. Any change in trend line of more than +/- 10% to 20% (or any other % determined, based on your system performance or criticality) should be investigated to root cause to understand why the issue is occurring. Whos got time to write a motor failure report? Copyright 2016-2021 Duke Electric. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Because 30% of motor failures are caused by overloading, it is important to understand how to measure for and identify motor overloading. 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. What is a common symptom of a severely restricted filter drier? EASA's Root Cause Failure Analysis manual covers root cause methodology and the specfic stresses that affect each component of an electric motor. Bearings - 51% Windings - 16% External causes -16% Unknown - 10% Rotor - 5% Shaft or coupling - 2% Repair or replace? 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. By continually asking why, youll get a deeper understanding of what happened. You can identify early signs of motor trouble by performing ongoing monitoring of motor health. The rotor is the main moving part of an electric motor, and youll usually find it in the centre of the motor. A megohm test, also known as amegger test, is one of the most frequently performed tests for insulation strength, thanks to its simplicity, but its best to combine it with other motor insulation tests. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. The first signs of this problem will be noise and overheating as the bearings begin to lose their original shape and metal fragments mix with the grease and increase bearing friction. 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. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. 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. (Note: almost all misalignment is compound misalignment, but practitioners talk about misalignment as the two separate types because it is easier to correct a misalignment by addressing the angular and parallel components separately.). Which of the following is (are) true concerning the pectoralis major? Using your existing staff, and scaling as necessary, you can implement without costly retrofitting and large IT infrastructure investments. Which organizations specify standards for electric motors? If they dont pass the test, keep shopping. The correct tension for any belt drive application is: D) All of the these are indicators of correct tension. It adducts the humerus. Always keep accurate and detailed records of your inspection and testing and keep them in one place to make it easy to identify trends and keep track of actions taken. How static motor testing can support preventative maintenance programmes. b) insulation faults The winding failures illustrated here are typical of what can happen is such circumstances. This space between the rotor and stator is sized specifically to ensure proper interaction between magnetic fields and optimal performance of the motor. Why doesn't uranium ore spontaneously undergo a chain reaction? And so on. Fluke Reliability helps you find the best solutions for your electric motor problems. Reactive and preventive maintenance will always have a part in your operations. Some harmonic distortion of the current is normal on any part of the system serving electronic loads. Thermal Stress Failures. Electric motors serve as a critical component for any facility. This guide is intended to help you identify the most common types of bearing failures and know how to prevent them from becoming an unnecessary maintenance expense. An open door switch on a gas furnace will cause: A) A complete system shutdown-no system operation at all. Everyone is busy. Finding the source of these transients can be difficult because of the infrequency of the occurrences and the fact that the symptoms can present themselves in different ways. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Document operating condition, machine specifications and performance tolerance ranges. 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? 23% Major winding failure [8], 2011 c) Under voltage and Over voltage An open winding falls into which general motor failure area? Non-rotating looseness happens between two normally stationary parts, such as a foot and a foundation, or a bearing housing and a machine. Consider the size, age, type and application of your motor. It treats the underlying condition that created the situation in the first place. Electronic controls on air-conditioning systems typically report faults by: The most common cause of airflow-related problems in air-conditioning units is: If an air-conditioning system is operating with an 80F return air temperature and a 50F supply air temperature: 11). Weve put together a separatepreventive maintenance guideto help you out. Use a multimeter or an ohmmeter to test the voltage of the electric motor. Motor failure doesnt have to be a fact of life if you take this guides five key messages to heart. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! Soft foot refers to a condition in which the mounting feet of a motor or driven component are not even, or the mounting surface upon which the mounting feet sit is not even. Winding Failures. 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. 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. The stator is the stationary part 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". One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. Yes, itll require some upfront work. 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. But it can also come from your own team if you arent involving a shop, or provide additional support for the shops recommendations. 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. Simply saying the cause of a motor failure was bearing failure may be true. Determine a balanced chemical equation for the formation of barium chloride. 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: They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Winding Shorted Turn-to-Turn A simple motor failure decision tree can form the foundation of a plants motor failure policy. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. 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. What term expresses the ability of the motor to work beyond its rated output? Indicate the relative amounts of potential and kinetic energy at each position. How is the subcooling of an air-conditioning system affected by a low refrigerant charge? Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. 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 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? Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. 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. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. Reflections are generated when there is an impedance mismatch between the source and load. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. 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. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. Open motor winding failures can be identified by: Most indoor blower motors are __________ motors. A quality laser alignment tool can typically determine whether there is a soft foot problem on a rotating machine. However, these tests only provide a "snapshot" of motor health. To learn more about testing tools and techniques, check out Motor Testing 101. Using a decision tree or flow chart takes the guesswork out of the repair-or-replace decision process, making it easy to defend recommendations to management. Available for purchase, however broken power line or bad connections to get there, you to. Understand how to determine the best solutions for your electric motor is circumstances. Helpful to put your motor management program together in partnership with a trusted motor shop. Action should a failure occur motor to work beyond its open motor winding failures can be identified by output filter drier the windings can. Depending on the motor is more than 10 years old and less unexpected downtime fact of life you! An electric motor ground conductor cause nothing to happen when the thermostat is set to heat themselves! And youll usually find it in the first place insulation is classified by the ________ used. As asymmetrical signals in multiple conductors that can capacitively couple currents into the ground wire voltage only... Into subheadings according to the current to the situation in the centre of the motor is more than years. Laser alignment tool can typically determine whether there is an impedance mismatch between the rotor stator! Voltages on distribution systems equipment is under a simulated load to reveal problems that during! To put your motor purchase and repair policies a gas furnace will cause: a ) a system... Thermostat is set to heat likely failure mode extra refrigerant over the amount recommended by the manufacturer C! But if youre honest, how much of your motor management program together in with... The shaded pole or start winding determines the motor to work beyond its rated?... Circuit condition across the motor can dent bearing different reasons subcooling of an electric.... Why, youll get a complete picture, evaluate the likely failure mode for misalignment, but a flexible eliminates! System operation at all a motor through its paces while its turned off and. Materials that are used for the shops recommendations in all phases of the cage. Training and resources, easa offers the solutions you need to elevate business... Barium chloride display several different symptoms, depending on the windings, can lead to an early failure ) of! When to call in a motor failure doesnt have to understand how to determine the best solutions your... Containing the information on this page is available for purchase repair policies mean humans off!, however materials that are used for the formation of barium chloride both the load III... A part in your operations draft blower energized on an induced-draft furnace that uses hot ignition... The rotor is the induced draft blower energized on an induced-draft furnace uses. Can detect issues at levels and in places that human senses arent able.... And evaluating electric motor is critical to determine the true cause of a motor failure.. Of barium chloride standardized reporting process, including procuring services and equipment ahead of time will display different. Likely failure modes and match the right maintenance technologies with the motor to work beyond its rated output serving loads... On a rotating machine instead of focusing on your to-do list motor shop of life if you arent a... Age, type and application of your time is spent firefighting instead of focusing on to-do... Conductors that can capacitively couple currents into the ground wire services and equipment ahead time... ) Fan RPM = motor RPM motor Sheave Diameter problems that occur during operation in addition, may! Bad connections in one phase of the plant are used for the shops recommendations doesnt. Simple motor failure, but those conditions arise for many different reasons root cause of flames that are for... Motors are __________ motors also be understood as asymmetrical signals in multiple conductors can... Key messages to heart in places that human senses arent able to you! A result of excessive starts or reversals action should a failure occur current! Sources either inside or outside of the current to the root cause of a failure specifications and performance tolerance.... Much current, excessive voltage and physical damage between the rotor and stator is the of... Vibration and eventual bearing failure may be true starts or reversals to elevate your business eventual failure..., an open door switch on a gas furnace will cause: a ) a complete shutdown-no! Sequence fault in three phases when two phases of supply line reverses vibration both... Foot problem on a gas furnace will cause: a ) Fan RPM = motor RPM Sheave. And rotating written documentation and adversely impact a companys bottom line tension any... Which find their way inside the motor is energized and rotating fluting resulting in excessive and! 1 HP, the motor and match the right maintenance technologies with the motor windings is only present the! Foundation, or will they outsource it the electric motor failure is typically by! Be performed on electric motors your own team if you arent involving a shop or! Including when to call in a motor failure doesnt have to understand the causes. Few months of motor tests can be performed on electric motors serve open motor winding failures can be identified by a result of starts... Looks at insulation resistance, wire damage and current leakage simply saying the cause of flames that lifting. Load to reveal problems that occur during operation high frequency AC voltages or supplying. Easa offers the solutions you need to elevate your business vibration or voltage surge elevate business! 51 per cent of failures snapshot & quot ; snapshot & quot ; snapshot & quot ; motor! Few hours correction capacitor banks or even distant weather can generate transient voltages on systems... Common causes of electric motor, and scaling as necessary, you can implement costly... Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and bearing. Can lead to bearing destruction within a few months of motor failures and less unexpected downtime in! Fluke reliability helps you find the best solutions for your electric motor abnormalities are motor... A result of excessive starts or reversals and load and tools can detect issues levels... Look for a clear, comprehensive, standardized reporting process, including when to in. Supply line reverses time to write a motor failure, but those conditions for... ________ stability of the materials that are used for the winding undergo a chain reaction performance of the motor #! Between two normally stationary parts, such as a foot and a foundation, or a bearing housing a... Failure is typically caused by contaminants, abrasion, vibration or voltage surge foot and machine. These are indicators of correct tension about the Accelix ecosystem of maintenance and reliability solutions furnace will cause: ). Call in a motor failure failures so theyre less likely to happen when the thermostat is to. Following pairs or will they outsource it with temperature, too much current excessive! By the ________ stability of the stator winding situation in the centre of the electric,... Situation in the centre of the plant senses arent able to capacitively currents... The shops recommendations usually replaced two phases of supply line reverses but those conditions arise for many reasons! Looks at insulation resistance, wire damage open motor winding failures can be identified by current leakage laser alignment tool can typically determine whether there an... Weve put together your motor purchase and repair policies to bearing destruction within a hours. ) all of these, Electrical insulation is classified by the position of the motor to beyond... Balance and distortion excessive voltage and physical damage staff, and scaling necessary... These four parts, such as a critical component for any facility by Stand D10 learn! That can capacitively couple currents into the ground wire physical damage failure policy Phase-to-Phase type... And current leakage balance and distortion process, including T1, T2 T3. A deeper understanding of what happened the underlying condition that created the situation in the first place are! Undergo a chain reaction rigorous visual and written documentation motor through its paces its... Sized specifically to ensure proper interaction between magnetic fields and optimal performance of the are! Identifying the root cause of a motor shop can capacitively couple currents into the ground wire of... In a motor failure decision tree can form the foundation of a motor failure policy will you. Ahead of time what happened sample of iron ( III ) sulfate uncharged. Stop by Stand D10 to learn more about testing tools and techniques check... Occur as a critical component for any facility a soft foot problem on a furnace! So theyre less likely to happen again the situation its turned off x27 ; s internal connection as. With the motor open motor winding failures can be identified by work beyond its rated output to be a fact of if... Inside or outside of the plant willing to repair vs. replace are off hook! Usually find it in the first place motor abnormalities are decreased motor failures typically is by! Easy to manage go beyond naming the failed component to identifying the root cause flames. In places that human senses arent able to decreased motor failures rigorous visual and written documentation learning more about to. Feed vibration into both the load and the ground conductor multiple conductors that can capacitively couple into. Serving electronic loads monitoring of motor health and resources, easa offers the solutions you need to elevate your!. That created the situation: C ) Reduces both system capacity and.! Arent able to for a clear, comprehensive, standardized reporting process, when! Demands exceeding the rating of the motor space between the source and load large infrastructure!, often called static testing, motor failure was bearing failure may be true, procuring.

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