HIMax System 9 Lifecycle
HI 801 001 E Rev. 4.01 Page 105 of 122
Heat Dissipation
A closed enclosure or a closed cabinet must be designed such that the heat generated
inside can be dissipated through the surface.
Choose the mounting type and position such that heat dissipation is ensured.
The power dissipation of the installed equipment is decisive for determining the fan
components. It is assumed that heat load and unhindered natural convection are uniformly
distributed.
Definitions
Size Description SI-Unit Engl. Unit
P
V
Power dissipation (heat capacity) of the elec-
tronic components within the device
W Btu*ft
A Effective enclosure surface (see below) m² ft²
B Enclosure width m ft
H Enclosure height m ft
T Enclosure depth m ft
Heat transmission coefficient of the enclosure W/m² K Btu ft/(h ft °F) k
Example of steel plate ~ 5.5 W/m² K
~ 9.5 Btu ft/
(h ft °F)
Table 46: Definitions for Calculating the Power Dissipation
Installation Type
In accordance with the mounting or installation type, the effective enclosure surface A is
determined as follows:
Enclosure installation type in accordance with
VDE 0660, Part 5
Calculation of the enclosure surface A
Individual enclosure, free-standing
on all sides
A = 1.8 x H x (W + D) + 1.4 x W x D
Individual enclosure for wall mount-
ing
A = 1.4 x W x (H + D) + 1.8 x H x D
Final enclosure, free-standing A = 1.4 x D x (W + H) + 1.8 x W x H
Final enclosure for wall mounting A = 1.4 x H x (W + D) + 1.4 x W x D
Central enclosure, free-standing A = 1.8 x W + H + 1.4 x W x D + H + D
Central enclosure for wall mounting A = 1.4 x W x (H + D) + H x D
Central enclosure for wall mounting
With covered roof area
A = 1.4 x W + H + 0.7 x W x D + H + D
Table 47: Installation Types
Natural Convection
When the natural convection is used, the lost heat is dissipated through the enclosure
walls. Requirement: The ambient temperature must be lower that the temperature within
the enclosure.
The maximum increase of temperature (ΔT)max of all electronic devices within the
enclosure is calculated as follows:
P
V
(ΔT)
max
= ———
k * A
The power dissipation P
V
can be calculated based on the specifications for the electric
power rating of the controller and its inputs and outputs.
To Next Page
Loading...
Need help?
General
