Engineering; Max. Ambient Temperatures; Power Dissipation; Engineering Of The Power Dissipation In Cabinets - Stahl 9170/21-30-10 Betriebsanleitung

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5

Engineering

5.1

Max. ambient temperatures

The ISpac isolators can be used over a wide temperature range. Depending on the isolator
version and installation method different maximum ambient temperatures may result.
Ventilation:
Installation: Single unit
Orientation: any
:
type
2
9170/21-30-10
Ventilation:
Installation: Single unit
Orientation: any
type:
2
9170/21-30-10
5.2

Power dissipation

Data sheets are describing the maximum power dissipation in standard operation. In
practice not all isolators are working with full load. Therefore engineering is done typically
with an average power dissipation of 70 % (P
Type
9170/21-30-10
5.3

Engineering of the power dissipation in cabinets

When electronic devices are integrated in cabinets free air movement is restricted and the
temperature rises. To minimise the temperature rise it is important to optimise the power
dissipation as well as the elimination of the produced heat inside a cabinet.
a) Natural Convection in closed cabinets
• Application: when the dissipated power is moderate and when the system operates in a
dusty or harsh environment
• Calculation of the maximum allowed power dissipation:
Pmax = ∆t * S * K
P [W] max. allowed power dissipation in the cabinet
max
∆
t [°C] max. allowed temperature rise
S [m²] free, heat emitting surface of the cabinet
K [(W/m²*°C)] thermal emitting coefficient (K=5.5 for painted steel sheets)
The calculated value for P
(70 % of max. power dissipation) of the installed isolators: Pmax < ∑ P
b) Natural convection in open cabinets
• Function: the heat is removed by cool air flowing through the devices
Without ventilation
vertical
70 °C 55 °C
With ventilation
vertical
70 °C 65 °C
Channels max. power dissipation
2
has to be smaller than the total average power dissipation
max
Leakage Monitor - Switching Repeater Type 9170/21-30-10
DIN-rail
any
60 °C
DIN-rail
any
65 °C
).
70%
70 % power dissipation
1.2 W
Operating Instructions
0.8 W
70%
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