Quick answer: Wind turbines and substations face cold steel, humid (often salty) air, big day–night temperature swings and long unattended periods: ideal conditions for condensation and corrosion of converters, switchgear, bolts and bearings. The usual protection is to keep the enclosed air below about 40–50 % RH (and its dew point below the coldest steel) during operation, standby, construction and storage. Because the air is often below 10–15 °C, desiccant dehumidifiers are the common choice: they keep working in cold air and do not need a condensate drain. Seal the protected volume, duct the regeneration air outside, and make sure the system runs during standby and after shutdowns.
Quick answer
- Target: RH below about 40–50 %, dew point below the coldest surface.
- Cold air (below about 10–15 °C): desiccant; warmer, staffed rooms: refrigerant may suit.
- Must run in standby and before restart; regeneration air ducted outside.
Where condensation and corrosion happen
| Location | Risk |
|---|---|
| Tower base: converter, switchgear, transformer | Electrical faults, tracking, corrosion |
| Nacelle and hub | Corrosion of bearings, gearboxes, electronics |
| Tower internal surfaces and flanges | Corrosion of bolts and steel |
| Offshore platforms and substations | Salt air plus humidity |
| Onshore substation buildings and cable basements | Moisture from cable ducts and soil |
Desiccant or refrigerant?
| Condition | Better choice |
|---|---|
| Air below about 10–15 °C, unheated spaces | Desiccant |
| No safe place to drain condensate, freezing risk | Desiccant (water leaves as vapour) |
| Low RH needed in cold air | Desiccant |
| Warm, heated, staffed rooms (substation control rooms) | Refrigerant may be more efficient |
See refrigerant vs desiccant and how a desiccant dehumidifier works.
Design points
| Point | What to define |
|---|---|
| Protected volume | Tower, nacelle, cabinets, rooms: which are kept dry, and how they connect |
| Leakage | Doors, hatches, cable openings; seal before sizing |
| Process air route | Dry air delivered where condensation risk is highest |
| Regeneration air | Ducted outdoors through a weather-protected outlet; intake away from exhaust |
| Power | Available in standby and during grid outages? |
| Corrosion and salt | Filtration on intake air; corrosion-resistant unit materials offshore |
| Controls | RH or dew-point control; alarms to SCADA |
Standby, construction and restart
Moisture problems often start when turbines are idle: during construction before grid connection, during long standby, or after outages when internal heat stops. Plan temporary or permanent dehumidification for those periods, and check humidity and insulation resistance before re-energising; see insulation resistance and humidity in electrical panels.
Monitoring and acceptance
- RH and temperature at several points (base, mid-tower, nacelle).
- Surface temperature on the coldest steel.
- Unit status and alarms to SCADA.
- Acceptance: RH held below target over a defined period including cold nights.
Products
Our wind power dehumidifiers and desiccant dehumidifiers (operating range −10 to +55 °C) are used for towers, nacelles and electrical rooms; for cabinets, see our electrical cabinet dehumidifiers. For high-altitude sites, check performance at site pressure; see high-altitude BESS condensation control.
FAQ
Frequently asked questions
Why do wind turbines need dehumidifiers?
To prevent condensation and corrosion in cold, humid, often salty air, especially during standby and construction.
What humidity should a wind turbine tower be kept at?
Typically below about 40–50 % RH, with the dew point below the coldest steel surface.
Why use a desiccant dehumidifier in a wind turbine?
It keeps working in cold air and needs no condensate drain.
Sources
- ASHRAE Handbook—HVAC Systems and Equipment, Desiccant dehumidification.
- ISO 9223, Corrosivity of atmospheres.
