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For a motor that will run in a cold store, the lowest temperature of the store is first compared with the ambient temperature range stated in the motor documentation, and then the moisture and condensation caused by the door opening are assessed. If the range does not cover the store's coldest value, further information on bearing grease, seals and insulation materials should be obtained before ordering.
How cold affects the motor
At low temperature bearing grease thickens; when the motor starts after a long standstill, friction and starting load go up. Shaft seals and gaskets can harden and lose their sealing. The motor's own heat reduces these effects while it runs, so the problem shows up mainly on the first starts after long standstills.
The real risk: condensation
A chilled motor that meets warm, humid air collects water on its internal surfaces. An anteroom with a door that opens often, or a loading dock, can be harder on the motor in this respect than the freezer room itself. Condensed water weakens the winding insulation and starts rust in the bearings. Where there are long standstills, measures such as an anti-condensation heater or condensate drain may be needed; as these are not counted among standard model features, the need should be discussed separately before ordering.
Which motors run in a cold store?
| Application | Environment | Point to watch |
|---|---|---|
| Evaporator fans | Inside the room, the coldest spot | Often compact motors specific to the unit; swapping for a foot-mounted IEC motor is not always possible |
| Conveying and stacking | Inside the room or on the dock | Starting after standstill and condensation |
| Condenser fans | Outdoors | Rain, sun and summer heat |
| Open-type compressor drive | Machine room | Belt ratio and starting load; the motor inside a hermetic compressor cannot be replaced on its own |
Information to state when ordering
- The lowest and highest temperature where the motor will sit
- Relative humidity and whether icing occurs
- Daily running and standstill times
- Mounting position and exposure to wash water or defrost water
For fan applications the axial fan motors page gives a good idea; for conveyor and fan drives you can compare suitable ratings in the three-phase motor shop.