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19. LOADING AND INSTALLATION
(3) Total 24VDC average power consumption of the output module (power consumption
equivalent to the points simultaneously ON)
The average 24VDC output circuit power of the power supply module is regarded as
the total power consumption of each module.
W
24V=I24V 24 (W)
(4) Average power consumption due to output voltage drop of the output modules
(power consumption equivalent to the points simultaneously ON)
W
OUT=IOUT Vdrop Output points that are simultaneously ON (W)
(5) Average input power consumption of the input modules (power consumption
equivalent to the points simultaneously ON)
W
IN=IIN E Input points that are simultaneously ON (W)
(6) Power consumption of the external power supply part of the special function module
W
S=I+15V 15+I-15V 15+I24V 24 (W)
The total of the power consumption values obtained for each block is power
consumption of the entire PLC system.
W=Wpw+W
5V+W24V+WOUT+WIN+WS (W)
Using this value (W), calculate the amount of heat generation and temperature rise
inside the panel.
The calculation formula to obtain the temperature rise inside a panel is shown as:
I
OUT : Output current (actual operating current) (A)
Vdrop : Voltage dropped across each output load (V)
I
IN : Input current (effective value for AC) (A)
E : Input voltage (actual operating voltage) (V)
W : Power consumption of the entire PLC system (the value obtained above)
A:
Surface area inside the panel (m
2
)
U : When temperature inside panel is kept constant by a fan, etc. ........... 6
When air inside panel is not circulated ................................................ 4
POINT
If the temperature inside the panel can exceed the specified range, it is
recommended to install a heat exchanger to the panel to lower the inside
temperature.
If a ordinary ventilation fan is used, it sucks dust together with the outside air and it
may affect the performance of the PLC.
UA
W
T=
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