8. LOADING AND INSTALLATION
8 - 6
MELSEC-
(6) Power consumption of the special function module power supply is expressed
as :
Ws = I
5V
×
5 + I
24V
×
24 + I
100V
×
100 (W)
The sum of the above values is the power consumption of the entire PLC
system.
W = W
PW
+ W
5V
+ W
24V
+ W
OUT
+W
IN
+ W
S
(W)
Further calculations are necessary to work out the power dissipated by the
other equipment in the panel.
Generally, the temperature rise in the panel is expressed as :
T = (
°
C)
Where, W = power consumption of the entire PLC system (obtained as
shown above)
A = panel inside surface area (m
2
)
U = 6 (if the panel temperature is controlled by a fan, etc.)
4 (if the panel air is not circulated)
POINT
If the temperature rise inside the panel exceeds the stipulated range, you are
recommended to install a heat exchanger in the panel to lower the temperature.
If an ordinary ventilation fan is used, dust will be sucked in along with the air
from outside the panel and this may affect the performance of the PLC.
W
UA
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