3 Connection Diagrams
3 - 3
source, however the heat dissipation area is a key factor to be considered. The internal
temperature rise can be estimated using the following equations:
(1) With a cooling fan, the permissible temperature rise shall be 1°C/6W/1m
2
.
(2) Without a cooling fan, the permissible temperature rise shall be 1°C/4W/1m
2
.
The equations indicate that for a cabinet having a heat dissipation area of 1m
2
and a 6W
heat source and a cooling fan (or 4W heat source without cooling fan), the internal
temperature rise shall be 1°C. The heat dissipation area is the total surface area of the
cabin minus the area in contact with the ground surface.
Ex.1: (with cooling fan)
heat dissipation area 2 m
2
internal permissible temperature rise 10°C
therefore the max. permissible heat source in the cabin is 6W×2×10 120W.
If heat source within the cabin exceeds 120W, a cooling fin or other heat
dissipation device must be provided.
Ex.2: (without cooling fan)
heat dissipation area 2 m
2
internal permissible temperature rise 10°C
therefore the max. permissible heat source in the cabin is 4W×2×10 80W
If heat source within the cabin exceeds 80W, a cooling fin or other heat
dissipation device must be provided.
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