
8. LOADING AND INSTALLATION
8 - 15
MELSEC-A
(2)
Wiring of I/O equipment
(a)
The applicable size of wire for connection to the terminal block
connector is 0.75 (18) to 1.25 mm
2
(14 AWG). However, it is
recommended to use wires of 0.75 mm
2
(18 AWG) for convenience.
(b)
Separate the input and output lines.
(c)
If the I/O signal wires cannot be separated from the main circuit wires
and power wires, ground at the PLC side with batch-shielded cables.
Under some conditions, it may be preferable to ground at the other side.
RA
Shielded cable
Shielded
sheath
DC
Input
Output
PLC
(d)
If wiring has been done with piping, ground the piping.
(e)
Separate the 24 V DC I/O cables from the 100 V AC and 200 V AC
cables.
(f)
If wiring over 200 m (0.12 mile) or longer distances, problems can be
caused by leakage currents due to line capacity. Take corrective action
as described in Section 11.4.
(2)
Grounding
Grounding must be done in conformance with (a) to (d) below
(a)
Ground the PLC as independently as possible. Be sure to ground to the
protective ground conductor (grounding resistance 100
Ω
or less).
(b)
If independent grounding is impossible, use the joint grounding method
as shown in the figure below (2).
PLC
Another
equipment
PLC
Another
equipment
PLC
Another
equipment
grounding
grounding
The protective ground conductor
(1) Independent grounding…Best
(2) Joint grounding…..Good
(3) Joint grounding…..Not allowed
(c)
Use a wire with a cross-sectional area of at least 2 mm
2
for grounding.
Make the grounding point as close to the PLC as possible so that the
grounding wire is not too long.
Содержание A1SH
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