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. Plot individual measurements to establish a baseline trend. It can also detect the presence of dirt or moisture. A. Bonnett and C. Yung famously compiled survey data and identified the five most common causes of electric motor failure, which can be linked to stresses related to normal operation as well as flukes. What is the most likely cause of flames that are lifting off the burner? runs a motor through its paces while its turned off. Skip to the next section on. A one horsepower motor with a service factor of 1.2 can safely produce: Manufacturers often recommend adding what component to split systems with unusually long refrigerant lines? Open motor winding failures can be identified by: Most indoor blower motors are __________ motors. Well help you select the right product for your needs. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. Once acid is identified in Motor control systems are being utilized in critical processes throughout manufacturing plants. It raises the clavicle. EASA's new streaming sales videos provide relevant and insightful training. 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. 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? It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. The winding failures illustrated here are typical of what can happen is such circumstances. (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.). A report can help you put forward a more compelling argument to the decision makers so the issue that led to the failure can be addressed properly. Switching power circuit, capacitor discharges, or solid-state power devices can also cause this type of motor winding damage This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. Tied with windings for almost 1 in 5 motor failures, external factors include temperature, contamination, poor maintenance, inappropriate mechanical loads and events such as flooding. This is another biggie. Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. Heres how to set your motors up for success, not failure. When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. Its responsible for 51% of motor failures. This weakness is . 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. 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 Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. (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. Temperature plays a major role in motor failure. The most common mechanical faults are shaft imbalance, looseness, misalignment, and bearings. 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? Skip to the next section on common causes of electric motor failure. Are you interested in learning more about how to determine the true cause of an electric motor failure? Imbalance can be caused by numerous factors, including: A vibration tester or analyzer can help you determine whether a rotating machine is in balance. Why doesn't uranium ore spontaneously undergo a chain reaction? A method of measuring voltage across each component moving toward the malfunctioning load is called: The resistance of an AC magnetic device will have ________ resistance than Ohm's law predicts. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Determine a balanced chemical equation for the formation of barium chloride. A) Adding refrigerant increases the system subcooling. A) Setting the thermostat below room temperature. 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. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. 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. These tools can assess electronic harmonics, distortion, and load studies. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. 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. On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. 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 be found in the motor cabling and is the sum of the current of the three phases at any one point in time. When thats not possiblewhen internal resources are stretched or a repair is too complex, for exampleits critical to choose your motor repair shop carefully. 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. 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. Physical damage, corrosion, improper installation and excessive loads are often the root cause. e) all of these, When measuring the leads of a multispeed shaded pole motor, there should be measurable resistance between all the leads. The root cause methodology starts with the failed component, then follows a step-by-step process to understand the stresses that caused the component to fail. If the motor is less than 1/8 HP, it is almost always replaced. Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). and preventive maintenance (PM). Should we repair the motor or replace it? Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Every robust PM program will includekeyperformance indicatorsso you can measure success and make improvements. Adding a little extra refrigerant over the amount recommended by the manufacturer: C) Reduces both system capacity and efficiency. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. Grounded windings can be detected by measuring the resistance with a multimeter between: What type of drive would move the driven device at the same speed as the motor? c) are hard to detect Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. What type of drive would move the driven device at the same speed as the motor? The voltage will be ________ immediately after the control that is opening the circuit. 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. Heres an example of the 5 Whys in action. Which of the following is (are) true concerning the pectoralis major? Contamination. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. It may also occur as a result of excessive starts or reversals. Indicate the relative amounts of potential and kinetic energy at each position. At the simplest level, all three phases of voltage should always have the same magnitude. 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). Lets take bearing failure, for example. That doesnt mean humans are off the hook, however. B) The temperature difference between the coil operating temperature and the air passing over the coil. (Here are7 ways to screw up vibration analysis.). 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. 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. Always ensure the motor thermal protector has not opened. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. That way you can save your bearing next time, instead of simply having it fail again. 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. Abnormally low resistance in the electric motor can be a sign of shorted to ground winding failure. 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. But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? 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. 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). 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. 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. Vibration and alignment tools are the best technology for diagnosing mechanical faults in rotating machines. 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. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. Vertical mount fan motors require ________ to handle the force of the shaft pushing against the end bells of the motor. 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. Already an expert? 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. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. Know the breakpoints at which youre willing to repair vs. replace. Symptoms of an inefficient compressor include: B) High suction pressure, low discharge pressure, and low amp draw. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. B) Call the equipment supplier and provide the system model numbers. An open winding falls into which general motor failure area? When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? Extent of failure. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. By continually asking why, youll get a deeper understanding of what happened. Motor design. Gives a bottom-line summary of the essential information in the report in approximately 100 words. Heres how a motor failure report can help with motor management. The questions are based on these four criteria. The correct tension for any belt drive application is: However, its important to move toward predictive maintenance programs. D) After the draft switch closes to prove the draft. 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. This report may come from your motor shop. If they can't, lubricate them. These faults also require rewinding or replacing the motor. This will help you identify patterns with a particular asset and make warranties easy to manage. Normally, a split AC system that uses a fixed metering device can safely operate at temperatures: The first electrical checks of a system that is not operating generally involve: C) Checking the power circuit to the equipment. Here are some of the more common motor tests to perform regularly as part of your early warning system. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Sales professionals need to keep their skills sharp in order to discover new leads, nurture promising prospects and close more deals. Not so fast. This is another biggie. 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. In fact, Cooper Bussmann says old age causes only 10% of electric motor 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. 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? Keep all of your organizations assets up and running without downtime. Bearings are the culprit in more than half of motor failure cases. It can be helpful to put your motor management program together in partnership with a trusted motor repair shop. | Site Design & Development by Human_Code. Most indoor blower motors are ________ motors. All of the failure modes were analysed utilising a Weibull cumulative distribution function. EASA-validated. Timing. Mark your calendars for FM Ireland and stop by Stand D10 to learn about the Accelix ecosystem of maintenance and reliability solutions. Infrared sensors can seamlessly integrate with a software platform that gathers data from many other sensor types. 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. Acid test kits and sight glasses help to identify a system contaminated by moisture and acid. Potential faults may be in the cabling to the motor, the terminations at the motor, and potentially the windings themselves. Smith, Michael Abbott. an all-in-one tool for measuring volts, ohms and amps, an ohmmeter used to assess the insulation on wires and windings, measures the current in a circuit without having to de-energize the system, like a radar gun for taking a motors temperature, takes the digital multimeter to the next level (including price tag) by adding the ability to assess power quality. 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. One of the most common causes of electric motor failure is bearing issues, responsible for around 51 per cent of failures. 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. A result of excessive starts or reversals current flow in one or more phases that then operating! 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