A) Setting the thermostat below room temperature. This website is using a security service to protect itself from online attacks. A common cause of an open winding is undersized lead lugs. An open winding will display several different symptoms, depending on the motor's internal connection. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. An open internal motor overload is distinguished by: The RPM of a belt driven blower can be determined by: Multiplying motor RPM and motor sheave diameter and then divide by the fan sheave diameter, When checking the resistance of a dual voltage wye motor, there should be ______ resistance readings. Iron(III) sulfate $\left[\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}\right]$ is composed of $\mathrm{Fe}^{3+}$ and $\mathrm{SO}_{4}^{2-}$ ions. 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. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. 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? Special rates good through June 1. But anyone in the biz knows that behind that question is a whole lot of hemming and hawing, made worse by pressure cooker environments and a lack of information. Weve spent most of this guide talking about what to do when a motor fails. If there is no resistance or the resistance is uneven, the motor is likely faulty. Sounds simple. Bearing failure is an expensive problem both in terms of motor repair and downtime, so helping to prevent this by measuring shaft voltage and bearing current is an important diagnostic step. 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. 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. Skip to the next section on. Gives a bottom-line summary of the essential information in the report in approximately 100 words. 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. EASA-validated. An open door switch on a gas furnace will cause: A) A complete system shutdown-no system operation at all. The open is usually caused by a blown fuse, an open contactor, a broken power line or bad connections. Thermal deterioration of insulation in one phase of the stator winding. b) insulation faults Which component failure could keep the fan from operating during the heating cycle on a traditional standing pilot gas furnace? Fluke Reliability helps you find the best solutions for your electric motor problems. Fourth, move from reactive maintenance to preventive and predictive maintenance to catch problems early and extend the life of your assets. When the liquid line is restricted, the supply of refrigerant to the metering device is reduced. Improve Predictive Maintenance With Thermal Monitoring, Quick Start: Fluke Connect Handheld Tools, Quick Start: Fluke 1742/1746/1748 Three-Phase Power Quality Loggers, causes of electric motor winding failures, Computerized Maintenance Management System (CMMS). 195.201.81.185 Keep all of your organizations assets up and running without downtime. Opens are indicated by infinite resistance or impedance reading. With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. to ask deciding whether to repair or replace your electric motor. Many professionals believe that a flexible coupling eliminates and compensates for misalignment, but a flexible coupling only protects the coupling from misalignment. Sigma currents are essentially stray currents that circulate in a system. 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. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. How efficient is the motor that failed? near the wall? 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. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. Will the shop do the work themselves, or will they outsource it? a) will draw higher than normal amps A) International Electrotechnical Commission (IEC). These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. Foreign bodies which find their way inside the motor can dent bearing . c) moisture Motor overload occurs when a motor is under excessive load. Nearly all air conditioning condenser fans are ________ motors. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Choose the more stable alkene in each of the following pairs. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. How unique is it? We've put together a post onwinding failure, with awesome photos courtesy of EASA, if you're looking for examples. Published: January 2021 In response to various opinions about the feasibility of maintaining motor efficiency during repair, including replacement of the stator winding, the Electrical Apparatus Service Association (EASA) and the Association of Electrical and Mechanical Trades (AEMT) conducted two comprehensive rewind studies . These next-generation maintenance and reliability tools support the generation, collection, and consolidation of data from sensors, tools, and existing systems. The failure mechanism involves the gradual development of a weakness in the insulation. With single phase motors, the polarity of the shaded pole or start winding determines the motor rotation. It is made of thin metal sheets, called laminations, instead of being solid, to reduce energy losses. 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. 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. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. (Here are7 ways to screw up vibration analysis.). Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. 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. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. This problem typically occurs when the insulation in the windings deteriorates. Theres a big difference between reactive maintenance and preventive maintenance (PM). 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). We can see your eyes rolling. Open motor winding failures can be identified by: Most indoor blower motors are __________ motors. Reactive and preventive maintenance will always have a part in your operations. Instrument to measure and diagnose: Fluke 810 Vibration Tester. Motors are rated in either ________ or _________ operation. That way you can save your bearing next time, instead of simply having it fail again. Contact us to speak with a specialist. 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. Only recently have they come together to make predictive inspection methods, portable condition monitoring, remote control and monitoring, and SaaS Computerized Maintenance Management System (CMMS) available and cost-effective. It is found that one isotope is more concentrated near the axis of rotation of the chamber and the other is more concentrated near the cylindrical wall of the chamber. The expected temperature drop through a direct expansion evaporator coil: D) Can be determined with a chart supplied by the coil manufacturer. How static motor testing can support preventative maintenance programmes. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. Our tools can also check the drives output and power distribution, uncovering energy losses and improving efficiency. Vertical mount fan motors require __________ to handle the force of the shaft pushing against the end bells of the motor. Engage locallyEASA's international membership is divided into 10 Regions that are made up of 32 Chapters. Often these mechanical faults are related: shaft imbalance, looseness, or misalignment left uncorrected will cause increased forces on the bearings which leads to rapid wear of the bearings. A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. Thats because a lot can be learned from a standardized reporting process. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Plant owners, operators, and managers can benefit from both integrated data and maintenance management with a single system. 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. 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. Various factors, such as overheating, physical damage . When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. A megohmmeter can detect: In either case, any soft foot condition must be discovered and remedied before proper shaft alignment can be achieved. Which failure could cause nothing to happen when the thermostat is set to heat? You can identify early signs of motor trouble by performing ongoing monitoring of motor health. a. A mixture of two common isotopes of oxygen, oxygen- 16 and oxygen-18, is put in a cylindrical chamber that is then spun around its long axis at a very high speed. This is another biggie. 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 Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Does the shop have experience with your motor? 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