electric motor bearing failure analysis pdf

4 TIMKEN BEARING DAMAGE ANALSIS WITH LUBRICATION REFERENCE GUIDE 2015 The Timken Company Let’s face it – bearings work in a tough world. A grease for life bearing means that the grease and rolling elements of the bearing are encapsulated and the bearing can’t be re-greased. Bearing-related problems are among the most common causes of motor failures. There are various common causes of motor failure, among which 45% are bearing failure, 35% are stator winding failure, 10% are rotor failure, and another 10% are other damages [4]. Most failures are caused by improper bearing use or inadequate maintenance. He has over 35 years' experience in generator and electric motor repair and engineering. x Special arrangements need to be made for vertical motors where these areas are inaccessible. Along with the photo is a brief explanation of the cause of the problem. For a more detailed answer to your questions please feel free to contact us by using the contact page or call . Sometimes the trouble lies within the power supply, including branch circuit conductors or a motor controller. The life of a three-phase stator winding can be shortened dramatically when the motor is exposed to unfavorable operating conditions — electrical, mechanical or environmental. What else could be causing the noise?" Motor failure studies in the 1980s determined that a given population of motors had either an average failure rate of 0.0708 Failures per Unit per Year (FPU) for general industry (2) or 0.035 FPU for maintenance intensive industries such as utilities (1). Examination of th6 failure mode ohn reveals the true cause of failure. In most cases, the cause of vibration is mechanical in nature, such as a faulty sleeve or ball bearings, too much belt tension, or improper balance. premature bearing - failure. Up to 80% of all electric motors are rebuilt due to bearing failure. As the motor runs, a track eventually forms where the bearing ball contacts the wall. Articles have been published stating that a significant cause of bearing deterioration is overheating. Vibration Diagnostics for Industrial Electric Motor Drives The induction motor is the most widely employed industrial electric-drive. Viewed under a scanning electron microscope, a new bearing race wall has a smooth surface (Photo B). what could happen if a pump motor shaft bearing froze? Spectrum Analysis The key features of analyzing spectra By Jason Mais SKF USA Inc. Summary This guide introduces machinery maintenance workers to condition m onitoring analysis methods used to detect and analyze machine com-ponent failures. Few failures are the result of true bearing steel fatigue. Do not use damaged housed units. Journal of Vibration and Acoustics 118: 242-251. It is important to understand that equipment usually fails over time, reliability decreases and losses increase (efficiency decreases) over time prior to most catastrophic failures. The squirrel cage induction motor's versatility and ruggedness continue to make it the workhorse of the industry, but that doesn't mean it's invincible. Find the cause of bearing failures.Bearings are built to last, so frequent failures may point to an installation or lubrication problem. However, it is important to note that in many cases a premature bearing failure is … bearing is the most vulnerable component in a motor drive system, accurate bearing fault diagnostics has been a research frontier for engineers and scientists for the past decades. All electric motors have their predetermined life span, typically ranging from 30,000 to 40,000 hours. (1997) A method for sensorless on-line vibration monitoring of induction machines. But, if not detected on time, vibration can reduce the life span of an electric motor, which then eventually leads to motor bearing failure or failure of windings. Analysis is at the manufacturing/assembly process level. ?his procedure is compli- cated by the fact that one failure mode may initiate another. Another possibility is that the driven load is jammed, binding or mismatched. Results of a bearing freezing up on shaft and breaking up- burning out motor windings Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons. When an electric motor fails to start, runs intermittently or hot, or continually trips its overcurrent device, there my be a variety of causes. The Focus is on manufacturing related deficiencies, with emphasis on Improving the manufacturing process ensuring the product is built to design requirements in a safe manner, with minimal downtime, scrap and rework. Electrical Damage (Fluting) Constant passage of alternating or direct current, even with low currents, can lead to electrical damage. By Mike Mavrigian. Electric motors should be installed very carefully and should be looked after at regular intervals. Explaining Motor Failure. However, this is dependant on proper maintenance - without which they are likely to break down much quicker. Bearings are located at both ends of the motor which are sometimes called "bell housings" or "end bells". Most of the electric motor failures occur at the start up. Failures are shown here to help identify the causes of failure, so that, where possible, preventative measures may be taken. We have tried adding grease to the bearing, which stops the noise for a while, but then the noise returns. This chapter describes characteristics of many popular analysis approaches and, in some cases, provides procedures and examples of these techniques. thermometers, and electronic stethoscopes help spot bearings in poor operating condition. Bearing Failure Analysis An ISO / TS 16949 Certifi ed Company 28397_GBC-Hyatt broch_R1.indd 1 12/23/11 11:36 AM. The winding failures illustrated here are typical of what can happen is such circumstances. Because of this, you must pay special attention to bearings, bearing housings, and shafts when carrying out inspections of and maintenance procedures for motors.When a motor fails, you … Electric motors:Types, Losses in induction motors, Motor efficiency, Factors affecting motor performance, Rewinding and motor replacement issues, Energy saving opportunities with energy efficient motors. x Motor Current Spectrum Analysis (at no load and 1 or 2 load point) x Power Quality Measurements Applicable for: HT Motors (only SCIM) Machine requirements: x Sensors need to be placed on motor bearing pedestal or body or mounting. Finally, a comparison between different motors is presented. Pushing it too hard for too long can cause the stator, rotor, bearings, and shaft to fail. When a bearing does fail, it is important to determine the exact cause so apprcipriate adiusfments can be made. Failure to follow these cautions may result in property damage. among which bearings are the most sensitive and vulnerable components. SKF bearing analysis experts can identify the cause of bearing failure and help you prevent it in the future. winding failure and possible causes,electric motor rewinds,illustrated guide to winding failures. Motor Current Signature Analysis for Bearing Fault Detection in Mechanical Systems ... Yacamini R and Smith K. (1996) Torsional vibrations in electrical induction motor drives during start-up. When electric motor fails – you can do few things, but before motor fails – you can do many many things to suppress eventual failure or heavy damage. 11. If half of all AC-motor failures are caused by bearing failure, almost 80 percent of these are caused by electrical damage to bearings.6. Begin to check the bearings of the motor. How to Fix it. Is this cause for concern? Leading standardization organizations have concluded that 30 percent of motor failures are attributed to insulation failure and 60 percent of these are caused by overheating. Most of them are caused by the over-heating of motor. There are also other factors which greatly affect the performance of electric motors such as low resistance, dirt, moisture, over-current and vibrations. "We have an electric-motor bearing that is making noise. The purpose of It informs the reader about common analysis methods. electrical motors work, and by simplifying the explanations to suit the intended reader. SKF research shows that, with proper installation and maintenance, bearings in electric motors often function properly for over 10 years. Company Overview General Bearing Corporation Headquarters West Nyack, NY General Bearing Corporation (GBC) occupies a unique position in the bearing industry. Solving those problems will reduce motor failures.Did you know bearing-related problems cause more than half of all motor failures? Brownish marks may be observed parallel to the axis on a large part of the raceway or covering the entire raceway circumference. The 2Z bearings are closed by a metal shield on both sides of the bearing … Many electric motor failures are caused by bearing failures. What to Look for. There are several types of bearings used. Thrust Bearing Failure Prevention & Analysis. The Do not use damaged bearings. The first step is to isolate the problem. manufacturing and assembly operations, … New bearing race. In 1995, new studies would support the original assumptions. Diagnosing the root cause of a thrust bearing failure can be simple, but often is tricky. This includes bearings greased for life in both the drive and non-drive end of the motor. However, electric motors are often out-of-sight, out-of-mind until production is down due to a burnout or catastrophic bearing failure. In recent years, electrical failures in bearing have been frequently reported in electric vehicles, and the electrical failure of bearings has become a key issue that restricts the lifetime of all-electric motor-based power systems in a broader sense. Riley CM, Lin BK, Habetler TG, et al. 2.1 Introduction Motors convert electrical energy into mechanical energy by the interaction between the mag-netic fields set up in the stator and rotor windings. Renowned for its ability to combine quality with competitive cost structures, GBC’s winning combination has been used … Excessive contamination. The bearings allow the shaft or rotor assembly to turn freely and smoothly in the frame. The easiest course of action is to take the necessary steps during engine assembly and installation to prevent the failure from ever occurring. The photos below are typical winding failures in three phase stators. Todd has a BS in Electrical Engineering, and his areas of expertise are: electrical and mechanical motor redesigns and engineering, root cause of failure analysis, and quality electric motor rebuilding. Heavy vibrations. Should the bearing be replaced? Identifying the vibration problems that can occur in induction-motor drives have an added complexity due to the rotating magnetic-fields in the machine. Poor lubrication. These merely scratch the surface of all … eight major causes of premature engine bearing failure, along with percentage figures which indicate how often each has been found to be the prime contributor to a bearing’s destruction. High heats. The text that was researched and compiled contains explanations of the motor parts, theory about electromagnetism and how current is used to make an electrical motor rotate.

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