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Industrial electric motor manufacturers provide their insights to a question posed by Reliable Plant. They were asked:
“In your opinion, what are the keys to maximizing the service life of industrial electric motors?”
This reply comes from John Malinowski, the product marketing manager for AC and DC motors at Baldor Electric Company.
“One of the keys to maximizing life in electric motors is to learn from your premature failures. Partner with a service shop and learn from the types of failures they see and document. Then, take actions to prevent these failures from happening to your other motors in similar applications. This may involve changing your maintenance procedures. Perhaps you need to grease more or less, or use a more compatible grease. Perhaps you need to identify voltage supply problems (for instance, if you have bearing fluting from an adjustable speed drive).
“Second, check to see if contamination and water are getting into the motors. If either one of these is an issue, do you have the right enclosure? Does the enclosure need a higher level of environmental protection? If so, look into severe duty, IEEE 841 or washdown motors.
“Finally, if you want to maximize service life, empower the plant maintenance and purchasing folks to buy better motors that will last longer and reduce energy consumption for years. Buying the lowest-cost item doesn’t always equate to the lowest life cost. Studies show that a motor’s purchase price is only 2 percent of its total life-cycle cost.”
For more information from Baldor, visit www.baldor.com.
This reply comes from Jim Bryan, the product service group manager for Emerson Motor Technologies.
“To maximize motor life, focus on proper lubrication and temperature.
“In regard to proper lubrication, bearings must receive not only a good, quality lubricant but the correct quantity at the proper intervals in order to obtain optimum life and reliability. Under- or over-greasing can be detrimental to reliability. Under-greasing does not provide the lubricant at the time it is needed, resulting in bearing wear or heat damage. Over-greasing can damage shields or significantly increase operating temperatures due to fluid shear friction. This reduces the grease’s lubricating capability. Oil-lubricated bearings must have the correct type and viscosity of oil for the same reasons stated previously. Closely follow manufacturer’s recommendations for lubrication types, amounts and schedules.
“In regard to temperature, this is the nemesis of electric motors. Overload, under-voltage, over-voltage, unbalanced voltage and improper ventilation can all work to increase the motor’s operating temperature. The overused rule of thumb is that motor life is cut in half for every increase of 10 degrees Celsius. Although the rule’s accuracy may be in question, it illustrates the point well. Any care given to mitigate the operating temperature will be rewarded with increased life and reliability. And, don’t make the mistake of increasing the rated capacity of a motor applied in a high ambient temperature environment to accommodate the winding temperature increase. Particularly on enclosed machines, this could result in unacceptable bearing operating temperatures, leading to early demise.”
For more information from Emerson, visit www.emersonmotors.com.