• Noise induction may occur if the Controller is installed in a panel that includes high-voltage devi-
ces. Wire and install them as far apart as possible. (Refer to Controller Installation Location on
page 5-86.)
•
Either install the Controller a minimum of 200 mm away from high-voltage lines or power lines, or
place the high-voltage lines or power lines in metal tubing and completely ground the metal tub-
ing to 100 Ω or less.
Example: Separating Controller from Power Lines
Metal tubing
200 mm
200 mm
High-voltage power panel
Power lines
Power
lines
Ground to 100 Ω or less
Controller
Controller
l
Other Precautions
• Digital I/O Units have both plus and minus commons, so pay attention to the polarity when wir-
ing.
5-5-6
Grounding
This section describes the earthing methods and precautions.
Considerations for Earthing Methods
Local potential fluctuations due to lightning or noise occurred by power devices will cause potential
fluctuations between ground terminals of devices. This potential fluctuation may result in device mal-
function or damage. To prevent this, it is necessary to suppress the occurrence of a difference in elec-
trical potential between ground terminals of devices. Y
ou need to consider the earthing methods to
achieve this objective.
The recommended earthing methods for each usage condition are given in the following table.
Specification of communications cables for
EtherCAT and EtherNet/IP
Earthing methods
Equipotential
bonding sys-
tem
Star earthing
Daisy chain
Connecting devi-
ces and noise
sources to sepa-
rate earth elec-
trodes
Connecting devi-
ces and noise
sources to a
common earth
electrode
The cable shield connected to the connector
hood at both ends of the communications cable
Recommend-
ed
Recommended
Not recommend-
ed
Not recom-
mended
Neither EtherCAT nor EtherNet/IP used Recommend-
ed
Recommended Not recommend-
ed
Not recom-
mended
5 Installation and Wiring
5-90
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)
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