5-23
5 Installation and Wiring
CP1E CPU Unit Hardware User’s Manual(W479)
5-3 Wiring
5
5-3-5 Relay Output Noise Reduction Methods
Take the following points into account when externally wiring I/O, power supply, and power lines.
• When multi-conductor signal cable is being used, do not combine I/O wires and other control wires in
the same cable.
• If wiring racks are parallel, allow at least 300 mm between them.
• If the I/O wiring and power cables must be placed in the same duct, they must be shielded from each
other using grounded steel sheet metal.
The CP1E PLCs conforms to the Common Emission Standards (EN61131-2) of the EMC Directives.
However, noise generated by relay output switching may not satisfy these Standards.
In such a case, a surge protector must be connected to the load side or other appropriate countermea-
sures must be provided outside the PLC. Countermeasures taken to satisfy the standards vary depend-
ing on the devices on the load side, wiring, configuration of machines, etc.
Following are examples of countermeasures for reducing the generated noise.
z Countermeasures (Refer to EN 61131-2 for details.)
• Countermeasures are not required if the frequency of load switching for the whole system with the
PLC included is less than 5 times per minute.
• Countermeasures are required if the frequency of load switching for the whole system with the
PLC included is more than 5 times per minute.
Reducing Electrical Noise for External Wiring
5-3-5 Relay Output Noise Reduction Methods
Power lines
Control cables
Power cables
PLC I/O wiring
Ground to 100 Ω or less.
300 mm min.
300 mm min.
PLC power supply
General control
circuit wiring
Low-current
cables
Power linesPLC I/O wiring
Ground to 100
Ω or less.
200 mm min.
Steel metal
PLC power supply
General control
circuit wiring
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