Calculation Of Heat Generated By The A2C System - Mitsubishi Electric MELSEC-A Series User Manual

6.
LOADING AND INSTALLATION
MELSEC·A
6.3 Calculation of Heat Generated by the A2C System
The operating temperature inside the panel where the A2C system is in-
I
stalled must be kept below 55°C. It is necessary to include heat dissipation
in the design of the installing panel employing heat calculation of the system
modules to be installed. In this section. the calculation procedure of
average power consumption of the A2C system is explained. Perform heat
calculation using the result of power consumption calculation.
I
Average power consumption
I
Power is consumed by the following areas.
•
[DC
I
L--ir-. . . .
[DC [
L_-i r-. . . .
[DC
I
L_-i r-. . . .
124v
24VDCline
$AC
Power
! ! !
............. power
supply
Output Input
Special
supply
module
module module
function
module
.
Reley
Input current Power
Transistors
(liN) x E supply
L-
Output current
I
Input
(Ioln)
x Vdrop
cpu
Output
power
module
;eJ
current
~(IIN)
(Ioln)
AC
E
~
LOAD
(1) Power supply module
Approximately 70% of the power supply module current is converted
into power with the remaining 30% dissipated as heat, i.e., 3{7 of the
41
output power is used.
3
Wpm
= -;
x (I24V x 24) 0N)
124v : Average current consumption of 24 VDC power supply for
output module internal consumption (current consumption
of simultaneous ON points)
... Not applicable when 24 VDC is supplied from outside and
the power supply module does not have 24 VDC output.
(2) Total 24 VDC output module power consumption (with an average
number of points switched on)
24V is supplied to drive output devices.
W24V
=
124V x 24 (W)
6-2