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Appendix 10
The ambient temperature inside the control panel where a head module is installed must be 55 or less.
It is necessary to know the average power consumption (heating value) of the equipment and devices installed inside
the control panel when designing a heat release structure of the panel.
This section describes the calculation method of the average power consumption of a programmable controller
system.
Calculate a rise in ambient temperature inside the control panel according to the power consumption.
Appendix 10.1
The total of the power consumption calculated for each block is the power consumption of the entire programmable
controller system.
W = W
+ W
+ W
PW
5V
Calculate a heating value and a rise in ambient temperature inside the control panel according to the calculated power
consumption (W). The calculation formula for a rise in ambient temperature inside the control panel is as follows.
W
T=
UA
W: Power consumption of the entire programmable controller system
A: Surface area inside the control panel [m
U (=6): When the ambient temperature inside the control panel is uniformed using a fan
U (=4): When the air inside the control panel is not circulated
• If the temperature inside the control panel is expected to exceed the specified range, it is recommended to install
a heat exchanger to the panel to lower the temperature.
• If a general-purpose fan is used, dust will be sucked into the control panel with the external air. This may affect the
performance of the programmable controller.
The calculation formulas for the power consumption of each block are as follows.
(1) Power consumption of power supply module
The power conversion efficiency of the power supply module is approximately 70% and 30% of the output power
is consumed as heat.
As a result, 3/7 of the output power will be the power consumption.
3
W
=
PW
7
I
: Current consumption of 5VDC circuit of each module
5V
I
: Average current consumption of 24VDC power supply for internal consumption of the output module (power
24V
consumption for the output points simultaneously turned on)
*1
Not applicable for the power supply module which does not have the 24VDC power output. (Power (24VDC) is externally
supplied.)
136
Calculating Heating Value of Programmable
Controller
Calculating the average power consumption
+ W
+ W
+ W
(W)
24V
OUT
IN
S
2
]
(I
v
5) + (I
v
24) (W)
5
24
*1
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