Rolling bearings in electric motors and generators

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www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071 6 Failure modes and corrective actions Electrical erosion . . . . . . . . 91 Inadequate lubrication . . . . 94 Bearing fatigue . . . . . . . . . . 96 Damage from vibration . . . 96 Damage caused by improper installation and set-up . . . . . . . . . . . . . . 97 Insufficient bearing load . . 99 Other damage . . . . . . . . . . 99 90 www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071
www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071 6 Failure modes and corrective actions Electrical erosion Failure modes and corrective actions Bearings are key components of electric motors and must therefore meet exacting performance criterion in terms of load carrying capacity and reliability. Today, SKF has the means to calculate bearing life with considerable accuracy, making it possible to match bearing life with the service life of the machine. There are cases, however, where a bearing does not attain its calculated life and there can be a number of reasons – some more obvious than others. 6 Bearings in electric motors can fail prematurely for a number of different reasons including: heavier than expected loads, inadequate or unsuitable lubrication, too light loads, damage during transport or standstill, electrical erosion, mounting problems, improper handling, contaminants inside the bearing, ineffective seals, or improper shaft or housing fits. Each of these factors produces its own particular type of damage and leaves its own special imprint on the bearing. Consequently, by examining a damaged bearing it is possible in the majority of cases to determine the root cause of the damage so that the requisite actions can be taken to prevent a recurrence. Electrical erosion The problem of an electric current passing through a bearing is common in electric motors and generators. This phenomenon, known as electric erosion or arcing, happens when a current passes from one raceway to the other through the rolling elements. The extent of the damage depends on the amount of energy and its duration. However, the result is usually the same: pitting damage to the rollers and raceways, rapid degradation of the lubricant and premature bearing failure. Recently, with the increased use of frequency converters, there has been a dramatic increase in the number of www.bergab.ru Берг АБ bergab@ya.ru Тел. (495)-228-06-21, факс (495) 223-3071 91
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Rolling bearings in electric motors and generators

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