Omron CJ2 User Manual page 161

Wire Layout for the Power Supply System
Observe the following points when wiring the power supply system.
• Separate the PLC power supply from the I/O device power supply and install a noise filter near the
PLC power supply feed section.
• Use an isolating transformer to significantly reduce noise between the PLC and the ground. Install
the isolating transformer between the PLC power supply and the noise filter, and do not ground the
secondary coil of the transformer.
• Keep the wiring between the transformer and the PLC as short as possible, twist the wires well, and
keep the wiring separate from high-voltage and power lines.
Wiring External I/O Signal Lines
Observe the following points when wiring external I/O signal lines.
• To absorb reverse electromotive force when an inductive load is connected to an output signal, con-
nect a surge suppressor near the inductive load in an AC circuit, and connect a diode near the induc-
tive load in a DC circuit.
Inductive
load
Connect a diode in a DC circuit.
Input Signal Noise Countermeasures
• Never bundle output signal lines with high-voltage or power lines, and do not route them in close
proximity or parallel to such lines. If output signal lines must be routed in close proximity to such lines,
place them in separate ducts or conduits and be sure to ground the ducts or conduits.
I/O cables
Power lines
Suspended ducts
• If the signal lines and power lines cannot be routed in separate ducts, use shielded cable. Connect
the shield to the ground terminal at the PLC, and leave it unconnected at the input device.
CJ2 CPU Unit Hardware User's Manual
Power supply for general operations circuits
Noise
filter
Power Supply System Diagram
PLC
Diode DC Input
Unit
Connect a surge suppressor in an AC circuit.
I/O cables Power lines
I/O cables
Floor ducts
I/O Cable Arrangement
Power circuits
Power supply for PLC input circuits
Power supply for PLC output circuits
PLC power supply
Outlet (for peripheral devices)
Inductive
load
PLC
Output
Unit
Output Signal Noise Countermeasures
Power lines
Conduit
5 Installation
Inductive
load
PLC
Output
Unit
Connect a diode in a DC circuit.
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