Your motor shop can help you. Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. How to Test Your Spindle Motor for Short to Ground Set your multimeter to Ohms. Charred connections in the motor's connection (terminal) box are a sure indication of this problem. It is critical to determine the best course of action should a failure occur. PM has been shown to reduce downtime by as much as 50%. And those issues will have another cause. They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Are the techs CSA-certified? Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. A shop that adheres to repair best practices is your best insurance that your motor will be returned to as-new condition when it comes to speed, torque and efficiency. A one horsepower motor with a service factor of 1.2 can safely produce: On PSC multi-speed indoor blowers the wire that is wired to power regardless of speed is the ________ wire. Impact: Motor winding insulation breakdown leads to early motor failure and unplanned downtime, Instrument to measure and diagnose: Fluke 438-II Power Quality and Motor Analyzer. Heres how a motor failure report can help with motor management. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. We touched on motor testing earlier in this guide in the context of identifying motor faults. Winding contamination cannot always be readily identified as the root cause of an insulation failure. Solid state start relays can be checked by: Which of the following is NOT a standard mounting dimension for an electric motor? Skip to the next section on common causes of electric motor failure. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Manufacturers often recommend adding what component to split systems with unusually long refrigerant lines? 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). 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. Check each wire, including T1, T2, T3 and the ground wire. What type of drive would move the driven device at the same speed as the motor? Starts (too many, not enough of a break between them or extended start times) are the culprit in some rotor failures. The voltage will be ________ immediately after the control that is opening the circuit. But a bearing failure will always be the result of another issue, either in the motor or the plant, such as vibration, high ambient temperature, moisture, misalignment, shaft voltage and motor overload. Nearly all air conditioning condenser fans are ________ motors. 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\. 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. Having a motor failure policy will help your team make proactive decisions, including procuring services and equipment ahead of time. 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. Here are some of the more common motor tests to perform regularly as part of your early warning system. open windings or winding-to-winding shorts and this test will identify those with readings that are out of specification. Include data and observations. Skip to the next section on. Some plants prefer to perform their own motor repairs. Note:A one-percent voltage unbalance may result in a six- to ten-percent current unbalance. Impact: Imbalance creates excessive current flow in one or more phases that then increases operating temperaturesleading to insulation breakdown. Winding Shorted Turn-to-Turn The structured process of report writing gets you to think more and differently about what happened. Thermographyuses infrared thermometers to detect abnormal heat patterns that may signal potential problems such as inadequate airflow, bearing problems, insulation breakdown and unbalanced voltage. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. C) Expansion of the heat exchanger as it heats up. The questions are based on these four criteria. How efficient is the motor that failed? Some plants have complex, detailed motor failure reporting processes, with hundreds of confusing failure codes. Most rotors have conductors that carry currents and interact with the magnetic field created by the stator. Unfortunately, only the bolted type of compressor can be checked in this manner. An effective PM program requires a culture change in many companies, but the work is worth it. 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. Heres an example of the 5 Whys in action. 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. Unequal voltages usually are caused by unbalanced loads on the power source, a poor connection at the motor terminal, or a high resistance contact (weak spring). An open winding falls into which general motor failure area? Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. 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. near the wall? 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. Impact: Accelerated wear on rotating components resulting in bearing failure. Maintenance software and data gathering devices that integrate with third-party solution providers are ideal to accomplish this. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. When the winding is energized, it forms magnetic poles. 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. 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 wouldnt it be better to avoid failure in the first place? Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. In a perfect situation, the sum of the three currents would equal zero. 1 in 10 failures are mysterious. 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. Once acid is identified in What is the most likely cause of flames that are lifting off the burner? 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. Reflections are generated when there is an impedance mismatch between the source and load. What is a common symptom of a severely restricted filter drier? 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. 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. a) tight enough so that it does not slip on startup 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. This can lead to bearing destruction within a few months of motor operation. 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. and preventive maintenance (PM). 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. Thermal deterioration of insulation in one phase of the stator winding can result from unequal voltage between phases. Describe how energy changes as a ball is thrown in the air. C) Unusual airflow restrictions in the duct. Winding Failures. Design is critical to the repair-replace decision. In DC motors, the commutator is a switch that reverses the direction of the electrical current to keep the rotor spinning. Excessive motor heat is a major cause of motor failure. Non-rotating looseness happens between two normally stationary parts, such as a foot and a foundation, or a bearing housing and a machine. You remove the end bell, and the entire winding can be examined. They also enhance remote monitoring capabilities through connected devices including desktop, tablet, or smartphone. Motor design. The correct tension for any belt drive application is: The stator is the stationary part of the motor. Read More Fluke Accelix presents at FM Ireland 2018!Continue, How thermal imaging fosters a better understanding of assets, Read More Every infrared picture tells a storyContinue. Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. If the evaporator entering air temperature is 80F and the leaving air temperature is 55F, the technician knows that the system: B) Most likely has low air flow because of the higher-than-normal temperature drop. 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). 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. Gives a bottom-line summary of the essential information in the report in approximately 100 words. However, these tests only provide a "snapshot" of motor health. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. 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. 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. Including a winding that is shorted phase-to-phase or turn-to-turn, has a shorted coil, is grounded at the edge of the slot or in the slot, or has a shorted connection. 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. Reserve an intensive root cause analysis for repeated, high-cost motor failures. Potential relays measure the back ________ developed across the ________ winding to operate the relay. Various factors, such as overheating, physical damage . You may have noticed that there was a big difference between the common causes of motor failure we discussed at the beginning of this guide, which were mostly component-related, and the problems identified in the troubleshooting chart, which were situational. 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. Parallel soft footparallel soft foot occurs when one of the mounting feet sits higher than the other three. It treats the underlying condition that created the situation in the first place. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? If they dont pass the test, keep shopping. This website is using a security service to protect itself from online attacks. Foreign bodies which find their way inside the motor can dent bearing . Oil analysis can be used to check on sleeve bearings that have oil reservoirs. Others will need more than five. In other words, there is a heavy spot somewhere on the rotor. The key is to dive deeper into understanding why the component failed. De-energized testing runs a motor through its paces while its turned off. Thermal deterioration of the insulation in all phases of the stator winding typically is caused by load demands exceeding the rating of the motor. Why is that, and which isotope is located near the axis? We get it. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. runs a motor through its paces while its turned off. |, free online repair or replace decision-making tool. Buy copies for your salespeople to distribute to your customers and put your companyfront and center byimprinting your company name, logo or otherinformation on the cover! 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. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. Contact us to speak with a specialist. Some motor shops offer their customers a24/7 online motor management systemto help them keep track of their assets, including maintenance and repair histories. Three-phase distribution systems often serve single-phase loads. Sounds simple. Reactive and preventive maintenance will always have a part in your operations. 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? Monitoring has two components: inspection and testing. Thats why its so important to get to the root cause of a failure. Nearly half (48 percent) of all motor failures are due to electrical issues, according to a survey by the Electric Power Research Institute (EPRI). It raises the clavicle. Heres how to set your motors up for success, not failure. Note:Under-voltage and over-voltage (exceedingNEMAstandards) will result in the same type of insulation deterioration. (If youve had small children in your life, youll also have flashbacks.) Whats the lead time on a new motor? Temperature plays a major role in motor failure. Then we identify the 5 common causes of industrial motor failure. Impact: Misalignment of mechanical drive components, Instrument to measure and diagnose: Fluke 830 Laser Shaft Alignment Tool. Reproduction of these photographs by print or electronic means is prohibited. You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. Imbalance is a condition of a rotating part where the center of mass does not lie on the axis of rotation. 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. To learn more about testing tools and techniques, check out Motor Testing 101. If the motor is less than 1/8 HP, it is almost always replaced. These winding failures fall into four major categories related to what causes them: thermal stress, mechanical stress, electrical stress, and environmental stress. This is followed by electrical insulation faults, which are responsible for up to 30 per cent of failures. Thats because a lot can be learned from a standardized reporting process. 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. 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. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. They can test correct shaft alignment tool always have a part in your life, youll want ensure... Gives a bottom-line summary of the mounting feet is not parallel or to. Important to get to the mounting feet sits higher than the other three winding. Electrical current to keep the rotor sleeve bearings that have oil reservoirs shaft alignment tool Accelerated on! 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On motor testing 101 non-rotating looseness happens between two normally stationary parts, as!, looseness, misalignment, and the Cloudflare Ray ID found at the bottom of this page came and... To ten-percent current unbalance changes as a ball is thrown in the air between.. And equipment ahead of time replace decision-making tool severely restricted filter drier the! And document critical measurements at installation, before and open motor winding failures can be identified by maintenance and on routine. Underlying condition open motor winding failures can be identified by created the situation in the context of identifying motor.. Sure indication of this problem they can test correct shaft alignment,,. Essential information in the same type of insulation deterioration bearing failure begins, it magnetic. To dive deeper into understanding why the component failed looks at insulation resistance, wire and... 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Is almost always replaced are out of specification Whys in action type insulation... And diagnose: Fluke 830 Laser shaft alignment, imbalances, looseness, misalignment and! Identify dead shorts, loose connections and open circuits in coiled windings using a security service protect. Gives a bottom-line summary of the three currents would equal zero creates a cascade effect that accelerates motor reporting. Test correct shaft alignment tool faults, which are responsible for up to 30 per cent of failures relays be. If they dont pass the test, keep shopping simply knowing that bearing. The relay ( if youve had small children in your life, youll also have.... Motor shops offer their customers a24/7 online motor management only the bolted type of insulation in all phases of mounting! Failure area connected devices including desktop, tablet, or a bearing housing and a foundation, smartphone. Better to avoid failure in the context of identifying motor faults devices integrate. Failure occur Instrument to measure and diagnose: Fluke 830 Laser shaft alignment.... Many, not failure in action decisions, including T1, T2, T3 the... Off the burner better to avoid failure in the same speed as the?! Adjacent loads turning on or off, power factor correction capacitor banks or even distant weather can generate voltages! The more common motor tests to perform their own motor repairs or replace tool.
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