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Operating Instructions
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:
9162/13-11-1*
70°C
Ventilation:
Installation: Single unit
Orientation: any
Type:
9162/13-11-1*
70°C
5.2 Power dissipation
Data sheets are describing the maximum power dissipation in standard operation (output
20 mA; power supply 24 V DC; load = 250 Ω). In practice not all isolators are working with
full load. Therefore engineering is done typically with an average power dissipation of 70 %
(P
).
70%
Type
max. power dissipation
9162/13-11-1*
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
14
Transmitter supply unit with limit values type 9162
without ventilation
DIN-rail
vertical
horizontal
48°C
56°C
with ventilation
DIN-rail
vertical
horizontal
58°C
60°C
1.65 W
has to be smaller than the total average power dissipation
max
pac-Carrier
vertical
35°C
pac-Carrier
vertical
52°C
70 % power dissipation
1.2 W
english
horizontal
50°C
horizontal
60°C
70%
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