Commonly, industrial and manufacturing plants require a backup inventory including motors and parts. A broken motor can mean missed deadlines, employee downtime, or spoiled product. These businesses depend on their motors to work so having a replacement motor on hand can help decrease costs in the long term.
Although the backup inventory is extremely important, the motor backups can stay in storage for several years if the replacement is not needed. Electrical Apparatus Service Association, Inc. (EASA) walks us through common factors to consider when storing a motor long term.
"A very important consideration in storage planning is the environment. There is consensus across all reviewed sources on this requirement. Electric motors should be stored in a clean, dry and vibration-free area. One of the most important recommendations for proper storage is that motors should be stored in an environment where the air is ventilated, clean and free from dust with additional care and planning for protection against the infiltration of a motor by insects and vermin while in long-term storage." - EASA
Common factors to consider include:
The motor should be stored between 5-60° C.
Relative humidity range of less than 50-75%.
The recommended maximum vibration level is not to exceed 0.15IPS (3.8 mm/s) or 0.8 mils (0.02mm).
Commonly, it is recommended to utilize the onboard space heaters to keep the winding temperature about 5° C above ambient. Recommendations from OEM's vary.
The recommendations for sleeve bearings are very different than those for grease-lubricated rolling element bearings. See the below linked EASA article for full details.
One of the key recommendations is to correct the megaohm reading to 40° C.
Generally speaking, store the motor in a climate-controlled environment with low vibrations. The area should be clean and free of dust. Review the below linked EASA article for the full article findings.