If motors are exposed to ambient vibration during storage, damage to bearings (such as false brinelling) can result. Ambient vibration can affect the motors when they are stored in close proximity to rail lines, production floors, and busy roads; if the motors cannot be stored elsewhere, then something should be done to dampen the vibrations. Effective dampeners include rubber, pallets, or old conveyor belts.
One of your critical electric motors just failed and you need to drop in a replacement electric motor as soon as possible. Fortunately, you have a spare. When you pull the spare from storage, you’ve got your fingers crossed that it will work without a problem. But you don’t have to depend on luck — there are certain steps you need to follow to ensure it will be ready to go when needed.
Storing Electric Motors
Correctly storing an electric motor involves more than just finding a spot for it on a shelf or pallet. Improper storage can lead to a host of problems that will delay how quickly a critical spare electric motor can be put into use and can even lead to expensive repairs or reconditioning. Motors represent a costly investment and should be stored with care, so here are some steps to preparing your valuable assets.
Record Keeping
In addition to keeping a record of the motors in storage, an ID card should be attached to each motor before it goes into storage. This card should include, at minimum, the date and time the motor was evaluated for storage as well as the evaluation report indicating multiple critical data points.
Carbon Brushes
For motors that have carbon brushes and will be stored for an extended period of time, the brushes should be lifted away from the slip rings/commutator with the springs in a relaxed state. Lifting the carbon brushes prevents possible chemical reactions and the springs should be relaxed to prevent weakening.
Protecting Surfaces
Any machined surfaces that are exposed should have a viscous rust preventative coating (such as LPS2, RustVeto, or Techtyl 502C) applied to protect them from corrosion. The same is true of sleeve bearings as well. Note that if the motor will be stored in an environment where moisture (including rain and snow) is problematic, then as much of the motor interior as possible should be painted. Otherwise, the use of a corrosion inhibitor should be enough.
Bearing Lubrication
Experts recommend filling the bearing cavities with grease prior to storage. This protects the bearings from the ingress of moisture. The excess grease can be purged when it is time for the motor to return to service. In addition, turning the bearings periodically will prevent the grease from settling on one side, leaving the other side exposed.
Controlling Ambient Vibration
If motors are exposed to ambient vibration during storage, damage to bearings (such as false brinelling) can result. Ambient vibration can affect the motors when they are stored in close proximity to rail lines, production floors, and busy roads; if the motors cannot be stored elsewhere, then something should be done to dampen the vibrations. Effective dampeners include rubber, pallets, or old conveyor belts.
Indoor Storage
Spare motors should not be stored outdoors, but rather indoors in an area that is clean and dry with minimal ambient vibration. Even for extremely large motors, the investment in building a facility for storing them is going to be a better option in the long run than the risk involved with storing an expensive motor outdoors. Also note that, when possible, motors should be stored in their original containers.
Ideally, your electric motors should be stored in a climate-controlled environment, but that isn’t always feasible. In such cases, it is wise to keep the windings at a temperature between 5°C and 10°C to prevent problems from condensation. This can be accomplished by using space heaters.
Measures to Take for Outdoor Storage
If you do have to store a spare motor outside, palletize it and then wrap it with a waterproof cover, leaving some breathing space at the bottom of the motor to prevent condensation from forming. Keep in mind that rain, snow, and ice aren’t the only threats a motor faces when stored outdoors.
Insects and animals (including birds and rodents) might decide to take up residence inside the motor and damage the windings. In addition, reasonable efforts should be made to prevent them from gaining entry to the motor. Effective methods include using mothballs or mothball crystals around the storage area perimeter, tucking scented dryer sheets in the container holding the motor or in the crevices of the motor, and/or placing steel wool in openings and drain holes.
Maintenance During Storage
Just because a motor is in storage does not mean it shouldn’t be maintained. For example, the shaft should be rotated at regular intervals so that the lubrication is redistributed, false brinelling is prevented, and, in larger motors, rotor sag is avoided. In addition, the shafts should be rotated so that the keyway stops in a different position, with experts recommending the use of 5-hour increments.
Another Option for Storing Electric Motor Spares
Finding a good place to store your electric motors safely can be challenging and may not always be feasible. Many electric motor repair shops, including Hi-Speed Industrial Service, offer storage solutions for your critical spare electric motors. When using such a service, you can rest assured that your motors will be stored in a climate-controlled facility that not only protects your motors from the elements but also ensures that they are part of an asset monitoring system that ensures they will be ready as drop-in replacements with minimal prep time.
Conclusion
Storing electric motors is more than finding a convenient spot to tuck them out of the way. Failure to consider the steps outlined in this post will lead to serious damage of extremely vital components such as windings, shafts, and bearings. If you need advice on storing your spares, or would like to learn more about electric motor storage services, contact Hi-Speed Industrial Service. We can help you determine the most effective way to safely store your critical spares!