38 Motor storage
Is your stored electric motor really ready for operation? Suzanne Gill gathers advice from AEMT members to help ensure that electric motors stored as spares are still up for the challenge when they are finally called into operational service.
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ecause electric motors are a crucial element of so many commercial and industrial operations, it is standard practice to store working spares on site to ensure fast response times in the event of a motor failure. For this reason, it pays to make sure that any stored motors remain operation-ready, and this requires correct management and regular servicing. Unfortunately, this is commonly overlooked, with many operations not putting enough emphasis on the correct management and servicing of stored motors. Matt Fletcher, Managing Director at Fletcher Moorland, emphasises the importance of ensuring that the shafts of stored motors are rotated at regular intervals. If the shafts are not turned, the bearing balls will start to wear at the point they rest on the bearing raceway. When the motor is finally put into operation, the bearings will likely fail very quickly. “Turning the shaft regularly while it is out of operation helps to minimise wear on any one point of the bearings, prolonging their life,” said Matt. "While most people acknowledge that this is necessary, we find that in practice, very few put it into action as no one person is tasked with the job.” Matt’s advice is that motor shafts
Quarter 2 2021
get a dozen or so full turns every month, using the keyway as an indicator that this is being done. For example, in January, the keyway is left pointing upwards, in February, it is left pointing to the left, etc., giving a clear visual indication that the task has been undertaken. Matt also highlights the importance of making this task someone’s responsibility as part of a maintenance schedule. Matt also advises that motors be kept clean while in storage. Often when the motor is not being powered, dust can enter via the cable glands. “I have also seen motors, after long periods of storage, blowing alarming amounts of dust and grime out of their channels when powered up.” Another area to consider is the shelf life of the grease in the bearings. “I wouldn’t advise leaving a motor with sealed bearings on the shelf for more than two years, as the grease inside the bearing will separate and so will not do a great job when it starts turning again,” said Matt. “If you are storing a motor with regreasable bearings, it is advisable to regrease them once every year or two. This can help prolong bearing life and will ensure that the motor is fit for service when needed.”
> 40 www.theaemt.com
