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3.5
Heat Design of Cabinet
!
CAUTION
In designing a cabinet, see the following explanations to ensure that the inside
temperature should not rise by more than 10°C over the external temperature (or a
rise of maximum 15°C is allowed only when the ambient temperature environment is
favorable).
3.5.1
Radiation inside Cabinet
As a general criterion, radiation volume inside the cabinet made of sheet metal can
be considered as follows:
(1) Radiation volume from the surface of the cabinet which is deemed an enclosed
cabinet:
W1
Where a circulating fan and a heat source of 5.5 W are inside the cabinet with
an effective surface area of 1 m
Here, the effective surface area is the cabinet's total surface area less floor
area.
Radiation volume from the surface of the enclosed cabinet can be expressed by
the following equation.
W1 = 5.5 × S × ∆T
S: Effective surface area of cabinet
∆T: Temperature difference = (Average temperature in cabinet)
For instance, to restrain the temperature rise within 10°C inside the enclosed
cabinet with a heat source of 165 W, an effective surface area of 3 m
needed.
165 = 5.5 × S × 10
Continued operation at a high ambient temperature around
the unit will shorten the life of the unit and cause faults.
[W]
2
, temperature rise inside the cabinet will be 1°C.
[W]
– (Outside air temperature)
2
S = 3 m
– 35 –
2
[m
]
[ °C]
2
is
STE 73843
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