Cleaning Motors and Generators with Dry Ice Blasting
Contaminated windings run hot, and heat is what kills insulation. Dry ice blasting restores cooling paths and cleans windings in place without solvents or disassembly.
Every 10 °C of additional winding temperature roughly halves insulation life. Dust, oil mist, carbon, and process debris on windings and cooling passages act as thermal insulation and drive that temperature up. Cleaning is not housekeeping on rotating equipment — it is life extension.
What gets cleaned
- Stator and rotor windings and end turns
- Air ducts, cooling fins, and radiator cores
- Frames, junction boxes, and terminal enclosures
- Exciters, slip rings, and brush rigging
- Oil-fogged surfaces around bearing housings
Why not solvent or water
Solvent wiping cannot reach between end turns and leaves residue that attracts new contamination. Steam and water require a full dry-out cycle and insulation resistance verification, adding a day or more to an outage. Dry ice reaches into the geometry, leaves nothing behind, and lets electrical testing proceed immediately.
Method notes
- Reduced pressure — commonly 40–80 psi on windings
- Fine or fragmented media rather than full-energy 3 mm pellets
- Increased standoff and constant nozzle motion; never dwell
- HEPA vacuum capture running continuously alongside the operator
- Insulation resistance and polarization index testing before and after
Where it fits in an outage
Winding cleaning typically sits after teardown inspection and before electrical testing. On a mid-size generator, cleaning that would take two shifts with solvent and rags is often a single shift with dry ice, and the surface is ready for testing immediately rather than after a dry-out.
Frequently Asked Questions
Can windings be cleaned without removing the rotor?+
Air-gap and end-turn cleaning is often done in place with extended nozzles. Full stator bore cleaning generally requires rotor removal.
Will blasting damage the varnish?+
Not at the pressures used for winding work. Aggressive settings can, which is why winding cleaning is a low-pressure, fine-media application.
Is any drying time required?+
No. The process is dry, so testing can proceed as soon as the surface reaches ambient temperature.
See the full motor, generator, and turbine scope on our equipment pages.
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