Mitsubishi Melsec-Q Series User Manual page 221

10.2 Calculating Heat Generation of Programmable Controller
The ambient temperature inside the panel storing the programmable controller must be suppressed to an ambient
temperature of 55
For the design of a heat releasing panel, it is necessary to know the average power consumption (heating value) of the
devices and instruments stored inside.
Here the method of obtaining the average power consumption of the programmable controller system is described.
From the power consumption, calculate a rise in ambient temperature inside the panel.
How to calculate average power consumption
The power consuming parts of the programmable controller are roughly classified into six blocks as shown below.
(1) Power consumption of power supply module
The power conversion efficiency of the power supply module is approx. 70 %, while 30 % of the output power is
consumed as heat. As a result, 3/7 of the output power is the power consumption.
Therefore the calculation formula is as follows.
3
=
W ×{(I ×5) + (I
PW 5V
7
I : Current consumption of logic 5 VDC circuit of each module
5V
I : Current consumption of 15VDC external power supply part of intelligent function
15V
module
I : Average current consumption of 24VDC power supply for internal consumption of the
24V
output module
In a redundant power supply system configuration, the same calculation method is applied.
(When 2 redundant power supply modules are placed in parallel, they run sharing the load current half-and-half.)
(2) Total power consumption for 5VDC logic circuits of all modules
(including CPU module)
The power consumption of the 5 VDC output circuit section of the power supply module is the power consumption
*1
of each module
W = I 5 (W)
5V 5V
*1: For the power consumption of the motion CPU and PC CPU module, refer to the instruction manuals of the
corresponding modules.
or less, which is specified for the programmable controller.
×15) + (I ×24)} (W)
15V 24V
(including the current consumption of the base unit).
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