Design is critical to the repair-replace decision. 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. quent compressor failure can result within a few hours. 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. 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. How long will it take to get the motor repaired? Impact: Accelerated wear on rotating components resulting in bearing failure. Terms and ConditionsCopyright 2016-2021 Duke Electric. Cost. Create an archive reference of measurements to facilitate trend analysis and identify change of state conditions. Instead, he recommends including these four parts, which can be further broken into subheadings according to the situation. Lets take bearing failure, for example. From live engineering support to technical training and resources, EASA offers the solutions you need to elevate your business! 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. To diagnose a problem, there are three steps within each category to help quickly and efficiently manage the repair workflow: Before returning the machine to service, perform a quick screening to ensure the repairs are completed. Impact: Arcing across bearing surfaces create pitting and fluting resulting in excessive vibration and eventual bearing failure. Whats the shops inventory of parts and materials for repairs? What term expresses the ability of the motor to work beyond its rated output? Failuresare shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. Need an Accredited service center?Find a service center that has proven they repair electric motors in accordance with ANSI/EASA's AR100. Others will need more than five. 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. 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. 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. The motor and insulation tester assure safe operation, prolongs the life of electrical systems and motors. 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. 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. Already an expert? Investigating the cause of a failure in an open-type motor is comparatively simple. You can identify dead shorts, loose connections and open circuits in coiled windings using a digital multimeter. Voltage surges are often the result of switching power circuits, lightning strikes, capacitor discharges and solid-state power devices. Sounds simple. And so on. Rotating looseness is caused by excessive clearance between rotating and stationary elements of the machine, such as in a bearing. An open winding falls into which general motor failure area? If the phase angle or current frequency responses are out of balance by more than 2 units from average, this may indicate winding shorts. Simply stated, harmonics are any unwanted additional source of high frequency AC voltages or currents supplying energy to the motor windings. 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. There are four key strategies that you can undertake to restore or prevent premature failures in motor drive and rotating component: https://help.fluke.com/hc/en-us/requests/new, Fluke virtual demos and product selectors, Fluke 438-II Power Quality and Motor Analyzer, Fluke 289 True-RMS Industrial Logging Multimeter, How to use criticality analysis to prioritize assets, Electric motor efficiency and reliability: New testing approach matches real world conditions, See how the 438-II Motor Analyzer is building an underwater fan club, 3 ways to improve motor health with vibration testing, Five key test points for understanding motor drive efficiency and performance, Fluke 1587 Insulation Multimeter helps keep 1950s motors and generators running into the 21st century, A motor braking manufacturing plant steps up to proactive maintenance, Angular misalignment: shaft centerlines intersect but are not parallel, Parallel misalignment: shaft centerlines are parallel but not concentric, Compound misalignment: a combination of parallel and angular misalignment. Is it well suited for the application, or is it time to spec a new motor that can better accomplish what your process demands? Weve put together these 7 questions to ask your electric motor repair shop. Insulation failures are typically caused by contaminants, abrasion, vibration, or voltage surge. Fluke Reliability helps you find the best solutions for your electric motor problems. A) 240 volts. A tri-fold brochure containing the information on this page is available for purchase. Then we identify the 5 common causes of industrial motor failure. Which NEMA classification can withstand the highest temperature? Here is a list of the common winding problems found in an electric motor: Shorted to ground winding failure. 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. Do they follow the ANSI/EASA AR100 best practices? This makes the perfect handout for your employees! Hot Surface Ignition System (HSI) controls lockout after how many unsuccessful attempts? That doesnt mean humans are off the hook, however. 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. 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. Unfavorable operating conditionswhether electrical, mechanical, or environmentalcan dramatically shorten the life of an electric motor. This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. 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! These losses dissipate in the form of heat, which, over time, will deteriorate the insulation capability of the windings. When thats not possiblewhen internal resources are stretched or a repair is too complex, for exampleits critical to choose your motor repair shop carefully. That way, action can be taken before its too late. 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. 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. Larger blower wheels are typically operated by ___________ motors. An open winding falls into which general motor failure area? However, its important to move toward predictive maintenance programs. Impedance mismatches can occur as a result of improper installation, improper component selection or equipment degradation over time. The voltage will be ________ immediately after the control that is opening the circuit. Which organizations specify standards for electric motors? Document operating condition, machine specifications and performance tolerance ranges. If the failure was catastrophic, repair may not be a good idea. Are the techs CSA-certified? All photographs are copyrighted 1985-2019byEASA. Contact us to speak with a specialist. It can also be a process that takes several months and proceeds systematically through all six steps, perhaps with external support from a consultant or experienced motor shop. 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. Some motor failures will require asking fewer than five whys. The imagers test faulty connections, overheated bearings, and tank levels. 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. Thankfully, computerized equipment and tools can detect issues at levels and in places that human senses arent able to. 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. This device checks motor speed, torque, power and efficiency, and also checks for motor insulation degradation. This condition can create a frustrating situation in which tightening the mounting bolts on the feet introduces new strains and misalignment. A failed bearing has increased drag, emits more heat, and has lower efficiency because of a mechanical, lubrication, or wear problem. Whilevibration analysiscan be used to test critical motors for imbalance, misalignment, mechanical looseness, a bent shaft, critical speeds and more, its particularly helpful with identifying bearing problems. To start investigating harmonic distortion, use a power quality analyzer to monitor electrical current levels and temperatures at transformers to be sure that they are not overstressed. Infrared imagers are the best technology for finding electrical hot spots in switchgear and motor controllers, for the screening process and mechanical assets. When is the gas valve energized on an induced-draft furnace that uses hot surface ignition? Improper lubrication, inappropriate mechanical loads, heat, contamination and shaft currents are all the usual suspects when it comes to bearing problems. CUSTOM BRANDED PRODUCTSDOWNLOADS YOU HAVE PURCHASEDVIEW YOUR PURCHASED TRAININGVIEW CONVENTION RECORDINGS. Does the shop have a significant amount of experience with your motor? 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. Failures disrupt business operations, decrease productivity, and adversely impact a companys bottom line. Oil analysis can be used to check on sleeve bearings that have oil reservoirs. Impact: Shaft misalignment and subsequent stresses on rotating components, leading the premature failures. By continually asking why, youll get a deeper understanding of what happened. 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. How efficient is the motor that failed? 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. The winding failures illustrated here are typical of what can happen is such circumstances. Winding Shorted Phase-to-Phase This type of insulation failure is typically caused by contaminants, abrasion, vibration or voltage surge. Various factors, such as overheating, physical damage . Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. Cloudflare Ray ID: 7a12d477b814c226 Copyright 2016-2021 Duke Electric. 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. If there is no resistance or the resistance is uneven, the motor is likely faulty. EASA's new streaming sales videos provide relevant and insightful training. 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. Monitoring has two components: inspection and testing. However, if the motor is more than 10 years old and less than 1 HP, the motor is usually replaced. Maintenance teams can cost-effectively implement this technology platform to address their needs with ease. If they dont pass the test, keep shopping. a) contamination 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. Why. Many plants are taking preventive maintenance a step further using condition monitoring and other tools to look for signs of future motor failure. 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? More than one response required. 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. These circulating currents can find their way through protective earth systems causing nuisance tripping or in some cases excess heat in windings. 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 Some plants prefer to perform their own motor repairs. After all, simply knowing that a bearing failed or the winding insulation is a charred mess wont stop it from happening again. 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