8. LOADING AND INSTALLATION
8 - 14
MELSEC-A
Precautions when wiring power supply cable are described.
(1)
Wiring power supply
(a)
Separate the PLC's power supply line from the lines for I/O devices and
power devices as shown below.
When there is much noise, connect an insulation transformer.
T1
PLC
200 V AC
Main power
supply
PLC power
supply
I/O power supply
Main circuit device
I/O devices
Main circuit device
Insulation
transformer
(b)
100 V AC, 200 V AC and 24 V DC wires should be twisted as dense as
possible. Connect the modules with the shortest distance.
Also, to reduce the voltage drop to the minimum, use the thickest wires
possible (maximum 2 mm
2
).
(c)
As a countermeasure to power surge due to lightening, connect a surge
absorber for lightening as shown below.
AC
E1
E2
PLC/IO
devices
Surge absorber for lightening
POINT
(1)
Separate the ground of the surge absorber for lightening (E
1
) from that of
the PLC (E
2
).
(2)
Select a surge absorber for lightening whose power supply voltage does
no exceed the maximum allowable circuit voltage even at the time of
maximum power supply voltage elevation.
Summary of Contents for A1SH
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