They can test correct shaft alignment, imbalances, looseness, misalignment, and bearings. Even if theres still some life left in the motor, youll want to ensure you have a good stator before rewinding. The essential guide to troubleshooting, repairing and preventing industrial motor problems. The correct tension for any belt drive application is: Opens are indicated by infinite resistance or impedance reading. d) can be detected by comparing the actual winding resistance to the motor manufacturer's data Click to reveal Impact: Premature wear on motor electrical and mechanical components leading to permanent failure, Instrument to measure and diagnose: Fluke Ti480 PRO Infrared Camera, Fluke 289 True-RMS Industrial Logging Multimeter. 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. 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. 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. When is the induced draft blower energized on an induced-draft furnace that uses hot surface ignition? 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. Which of the following formulas can be used to calculate fan speed (RPM)? Should we repair the motor or replace it? Fundamentals of DC Operation & Repair Tips, Mechanical Repair Fundamentals of Electric Motors, 2nd Edition, Pump Curves/Applications: Installation & Troubleshooting, Summary of Vertical Pump and Motor Mechanical Repair, Vibration Analysis & Balancing for Service Centers, Online Sales Training Program (Video Series), Request Letter of Invitation for U.S. Visa, Getting the Most from Your Electric Motors. Terms and ConditionsCopyright 2016-2021 Duke Electric. The resistance of ________ can accurately be predicted using Ohm's law. With the motor running, you can perform dynamic testing to identify issues with temperature, balance and distortion. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. 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 Thermal deterioration of insulation in one phase of the stator winding. If the reading is infinite, your motor should be fine. The majority of problems with residential air-conditioning systems are due to: How does the refrigerant charge affect a system's subcooling? Three-phase distribution systems often serve single-phase loads. The questions are based on these four criteria. EASA-validated. 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. Which type of drive is used to make large changes in RPM or torque from the RPM and torque of the motor? If they can't, lubricate them. De-energized testing runs a motor through its paces while its turned off. The imagers test faulty connections, overheated bearings, and tank levels. Instrument to measure and diagnose: Fluke 810 Vibration Tester. If the failure was catastrophic, repair may not be a good idea. Second, formalize your documentation and reporting so its easy to get all the information about a particular motor to the people that need it. 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. Special rates good through June 1. 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. Connected tools and sensors offer all key stakeholders with access to the data they need. Weve spent most of this guide talking about what to do when a motor fails. That way your chosen solution doesnt just treat the symptom. 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? Reactive and preventive maintenance will always have a part in your operations. You can email the site owner to let them know you were blocked. 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. Need an Accredited service center?Find a service center that has proven they repair electric motors in accordance with ANSI/EASA's AR100. A megohmmeter can detect: To get there, you have to understand the underlying causes of motor failures. 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. 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. This makes the perfect handout for your employees! Copyright 2016-2021 Duke Electric. d. It flexes the humerus. For example, a transient may appear on control cables that dont necessarily cause equipment damage directly but may disrupt operations. C) Unusual airflow restrictions in the duct. Shaft failure is the least common cause of motor failure. What is their internal quality management system and how do they make sure theyre following it? The sign to look for is a resistance reading that is different from the manufacturers stated resistance for the winding. 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 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. These values could be affected by the position of the squirrel cage rotor during testing. How many years of experience do they have? Winding shorted phase-to-phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Motor windings account for about 32% of all AC electric motor repairs. The machines provide the data. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. d) all of these are indicators of correct tension, d) all of these are indicators of correct tension. 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. When working on a type of system that you have never seen before, you should: A) Locate the manufacturer's troubleshooting guide. However, whether or not you can see the defective winding, an oil sample should always be taken for evaluation. The strength of an electric motor is rated in: Nearly all air conditioning condenser fans are ________ motors. c) moisture Then we identify the 5 common causes of industrial motor failure. 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. Re-state what you felt caused the failure. Identify causes you eliminated and why. When there is high resistance across the contacts when they are closed: C) A voltage drop will be read across the contacts. Physical damage, corrosion, improper installation and excessive loads are often the root cause. Various factors, such as overheating, physical damage . Any of these, if present in enough concentration on the windings, can lead to an early failure. Instead, rely on the U.S. Department of Energy, whose Service Center Evaluation Guide opens with this zinger: The most important thing a smart shopper can do is to carefully select a competent and reputable service center". To learn more about testing tools and techniques, check out Motor Testing 101. Third, make your motor repair and replace decisions using an industry-accepted decision tree oronline decision toolto standardize and speed up your process. 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? Transient voltages can come from several sources either inside or outside of the plant. The primary symptoms that accompany a motor overload are excessive current draw, insufficient torque and overheating. When the winding is energized, it forms magnetic poles. 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. Design is critical to the repair-replace decision. 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. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! This imbalance can lead to stresses in each of the phase circuits in a three-phase power system. To help mitigate these failures, a variety of motor tests can be performed on electric motors. b) insulation faults Motor overload occurs when a motor is under excessive load. Capture and document critical measurements at installation, before and after maintenance and on a routine basis. 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. 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. Winding Shorted Turn-to-Turn Organize the content under subheadings that make sense. From its position in the periodic table, determine which atom in each pair is more electronegative: (a) N or P (b) N or Ge (c) S or F (d) Cl or S (e) H or C (f) Se or P (g) C or Si. Fluke Accelix presents at FM Ireland 2018! Find out in less than 2 minutes. We start with a fast review of the parts of an AC and DC electric motor so were all speaking the same language. 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. But if youre honest, how much of your time is spent firefighting instead of focusing on your to-do list? Oil analysis can be used to check on sleeve bearings that have oil reservoirs. 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. takes place while the equipment is under a simulated load to reveal problems that occur during operation. The rotor is sometimes called an armature. 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. Reflections are generated when there is an impedance mismatch between the source and load. Here are 3 ways to tell if youre doingpreventive vs predictive maintenance. PM has been shown to reduce downtime by as much as 50%. How unique is it? Which organizations specify standards for electric motors? The failure mechanism involves the gradual development of a weakness in the insulation. Excessive motor heat is a major cause of motor failure. 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. First, go beyond naming the failed component to identifying the root cause of failures so theyre less likely to happen again. That doesnt mean humans are off the hook, however. All rights are reserved. It may also occur as a result of excessive starts or reversals. 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. . Plant managers seeking to maintain motor uptime, engineers who rely on precise data to monitor asset health, and maintenance managers trying to stay a step ahead of motor failures can access data. 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). 4. Angular soft footangular soft foot occurs when one of the mounting feet is not parallel or normal to the mounting surface. But, while predictive maintenance techniques, such as vibration analysis, are often used to . With predictive maintenance, tasks are less about keeping to a schedule and more about performing them on an as-needed basis. Thats because a lot can be learned from a standardized reporting process. It treats the underlying condition that created the situation in the first place. 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 . Potential relays measure the back ______ developed across the _______ winding to operate the relay. Do they follow the ANSI/EASA AR100 best practices? Get thebearing failure checklist. Common causes of winding failure include high temperature, too many starts, contamination, too much current, excessive voltage and physical damage. A carbon brush probe attachment allows you to measure shaft voltage while a motor is rotating. Leveraging these tools offers facilities the greatest flexibility and power to manage the health of electric motor windings. (If youve had small children in your life, youll also have flashbacks.) 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. When charging a capillary tube system that holds 100 oz., the charge must be: B) Within 5 percent, between 95 and 105 oz. 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. Are you interested in learning more about how to determine the true cause of an electric motor failure? 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. Which NEMA classification can withstand the highest temperature? Impact: Decrease in motor efficiency results in added cost and an increase in operating temperatures. To get a complete picture, evaluate the likely failure modes and match the right maintenance technologies with the most likely failure mode. 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. Heres how a motor failure report can help with motor management. These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. Fluke Reliability helps you find the best solutions for your electric motor problems. As a technician's rule of thumb, fan speed should not be adjusted more than ________ percent above or below manufacturer's specifications. Thats why its so important to get to the root cause of a failure. Variable frequency drives employ a pulse width modulation (PWM) technique to control the output voltage and frequency to a motor. Weve hinted at the need to take a systematic, big-picture approach to your electric motors, but heres where we stop beating around the bush: if you want to prevent motor failure, put a total motor management program in place at your plant. A winding failurewhich is often caused by a breakdown of the windings insulationwill cause a short in the motor. Explain your reasoning. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. A) 240 volts. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? You remove the end bell, and the entire winding can be examined. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. Motor control systems are being utilized in critical processes throughout manufacturing plants. (Here are7 ways to screw up vibration analysis.). Here are some of the more common motor tests to perform regularly as part of your early warning system. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. 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". Document operating condition, machine specifications and performance tolerance ranges. Motors are rated in either ________ or _________ operation. Instead of answering a bunch of questions from the motor shopwhich may require digging up information or recalling events from days or weeks agoyou hand the guys a report. Energized testing takes place while the equipment is under a simulated load to reveal problems that occur during operation. Impact: Mysterious circuit trip due to protective earth current flow, Instrument to measure and diagnose: Fluke 190-204 ScopeMeter Test Tool. 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. 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? Temperature plays a major role in motor failure. Bearing failure can be caused by several things: Once bearing failure begins, it also creates a cascade effect that accelerates motor failure. This offline testing, often called static testing, looks at insulation resistance, wire damage and current leakage. 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. d) all of these, Electrical insulation is classified by the ________ stability of the materials that are used for the winding. Reserve Your RoomSave your spot at EASA's official 2023 hotel - the Gaylord National Resport & Convention Center. 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.