Forced Air Cooling
Providing air flow over the heatsink with a fan or blower. On the same profile it lowers the thermal resistance typically 2-4 times compared with natural convection; that is, you can dissipate several times more loss power for the same temperature rise. In return, dust, filter maintenance and the fan's own failure risk are added to the system.
The gain from forced cooling is large but not free. In a fan-cooled design the continuity of the cooling now depends on a moving part.
- Air direction: Taking cool air into the cabinet at the bottom and expelling hot air at the top is the most efficient, because it works in the same direction as natural flow.
- Filter: A cabinet without a filter draws dust inside; a dusty heatsink gradually gains an insulating blanket. If you fit a filter you have to plan periodic cleaning.
- Fan failure: When the fan stops, the system falls back to natural convection. If you designed only for the fan-cooled condition, this means thermal shutdown or damage within a short time.
- Life: The life of bearing fans shortens noticeably with temperature; they must be included in the maintenance plan.
In damp or dusty field conditions, instead of drawing air inside, connecting the sealed housing to a metal carrier as a heat path is often a more reliable solution.
The context in which this term is used: DC Motor Driver Selection Guide