Two Minute Tips  

Motor Storage

Noah Bethel
Noah Bethel | Vice President-Product Development, PdMA Corporation

Proper motor storage is critical if we hope to achieve normal life expectancy from our electric motors. Not only is proper motor storage important for good motor health, it may be required to maintain a warranty on motors that we purchase.

Storage Preparation:

  • Store indoors in a clean dry environment.
  • If you know the motor will be stored when purchasing it, request the motor be packaged for long term storage.
  • Ensure no floor or building vibration is present (if unable to prevent vibration then lock the shaft).
  • Connect and energize space heaters to ensure the machined components and insulation are above the dew point and free of condensation.
  • Treat storage facility for unwanted guests like rodents and bugs.
  • Apply rust preventative coating on shaft and machined surfaces.
  • Oil from bearings is drained for shipment, but if storing for more than one month re-fill oil reservoirs to the max indicated level.

Storage Maintenance

  • Every two months measure and record insulation resistance-to-ground (RTG).
  • Every two months ball and roller element bearing shafts should be manually rotated.
  • Monthly inspect the oil level in oil bath bearings and the rotate the shaft at least 30 revolutions to re-circulate the oil.
  • Every twelve months replace the oil in oil bath bearings.
  • Motors with brushes should be inspected to ensure the brushes are not in contact with the slip rings or commutators.

Installation Preparation

  • Perform full offline MCE testing on motor in storage paying special attention to insulation RTG to verify insulation condition has not decayed or become contaminated with moisture. One thumb rule says a drop of 50% from your original measured RTG in storage indicates a likely moisture intrusion. If moisture is suspect initiate a drying procedure before starting.
  • Remove old grease and oil and replace with new lubricant in accordance with motor manufacturer guidelines.
  • Clean off dust and dirt and remove any anti-corrosive agent from surfaces.
  • Inspect commutator/sliprings and re-insert brushes. Verify brushes move freely in holder.
  • Re-install shipping brace before moving motor from storage.
  • Perform offline MCE testing on power cables before and after connecting motor to confirm the health of your Power Circuit.
  • Capture In-Rush/Start-Up test on initial start to confirm health of Power Quality.
  • Capture all Emax running tests at load to confirm Stator, Rotor, and Air Gap conditions.
  • Perform Vibration analysis test at load to confirm bearing, mechanical, and machine train condition.

Refer to motor manufacturer guides for additional details on motor storage.

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